The limits of the milieu for a certain organism strictly pertain to a certain stage in its development. The milieu for a larva and for an imago may be different. Still, we might consider an integration of the boundaries for a certain stage, as long as that stage requires a constant milieu. Geobiologically this is an organism distinct from another developmental stage. Potential milieu is limited by the faculties of the organism itself. These faculties, these properties, may never be ascertained completely. Dr. B. Hubert, for example, found a fungus (Oospora) growing on a solution (8 %) of vanadium chloride.1 It seems improbable that the faculty to withstand this chemical is known of many other organisms. Temperature, pH, radiation and pressure range should be equally investigated, and the influence of every known chemical. It seems clear therefore that the boundaries of the potential milieu are the widest. The picture we obtain of the organism in the laboratory, the laboratory milieu, shows a much more modest extension of the boundaries. We may encounter a certain insect only in certain localities, the area total of the environmental factors at those localities we call the natural milieu. But the possibilities of the organism in question may be limited. It may be (as in the case of Opuntia, rabbits, wild cats etc.),2 that there are large tracts of this earth equally suitable. If we take those into account, we widen the milieu limits again to the terrestrial milieu. The accompanying graph (Fig. 3.1) illustrates the idea.

In this book we shall, as far as possible, carefully designate which type of milieu is meant. If for a number of organisms, the laboratory milieu is known, the simultaneous occurrence of these organisms in nature often gives a sufficient description of the milieu, even without subsequent chemical analysis!

In the Figure 3.2, A, B, C and D represent milieu boundaries of four distinct organisms, it is clear that the “common denominator” (P) only gives a close description of the milieu. Inversely, by knowing the properties of a certain milieu, we may predict the occurrence of certain organisms.

In the next figure (Fig. 3.3) a biocoenosis of the solar salt works is given, the milieu factors salinity, acidity and temperature being considered. The boundaries of a number of organisms are given:3

A = Artemia salina, a phyllopod Crustacaea.

D = Dunaliellaviridi, a polyblepharid, green flagellate.

L = Lochmiopsis sibirica, a filamentous, green alga.

B = Purple sulphurim spirullaria.

N.B.Dunianella viridis occurs over the entire area.

The above examples are taken from hydrobiology. Oceanic biology and limnology, have a great advantage of dealing with homogeneous milieu or rather (as in stratified waters) with a different number of homogeneous milieus. Nearly all of our considerations pertain to these and similar environments, as the soil and the rock are highly heterogeneous and therefore difficult to characterise.

The laboratory milieu, when sufficiently characterised, enables us often to other specific organisms from an arbitrarily inoculum (garden soil, ditch mud, dust etc.). The milieu has a selective action. If we assume (Section 1) microbes to be omnipresent,4 the definite question put by the composition of a well defined milieu will call for a definite answer in the form of the appearance of the vegetated (non-latent) stage of the organism resonating with this syndrome of milieu conditions. Various examples may be given. We must not forget however the laboratory milieu cannot enlighten as completely on the process of an organism. The potential milieu is perhaps not even known to the organism itself, in as much as conditions have never been varied enough to test its width.

3.2.1 Introduction

Radiation has several important properties as a milieu factor. In the first place it is absorbed by all molecules and changed in heat. This means that the average molecular velocity is increased. Further it may import some of its energy to substances raising the energy potential of these substances. In both cases useful work may be performed in the first case (heat movement) water evaporates which may be condensed at higher elevations, where it can be used to drive a turbine. In the second case out of carbon dioxide and water, sugar may be found which kinetic energy has been changed into potential energy (quantum h V, in which V = frequency; h = Planck constant = 6.1 × 10-47).

3.2.2 The sun as incandescent body

[Baas Becking inserted Fig. 3.4.]

Nearly all the radiation we receive comes from the sun. This is an incandescent body of ±6500 °C, according to the wavelength of the most intense radiation at 5500 Å (Rayleigh’s law T = cλ4).

[Baas Becking further inserted Table 3.1 which compares the intensity of light during day and night.]

3.2.3 Radiation on earth

[Baas Becking left this section blank.]

3.2.4 Influence of latitude

[Baas Becking left this section blank.]

3.2.5 Influence of atmosphere

[Baas Becking left this section blank.]

3.2.6 Seasonal changes


3.2.7 Actual results

Here measurements with the Amalux,6 as used at Leyden, and the solar meter are given. a. Zuyderzee 1935.7b. Somme 1937 and as many of the records I took in Australia. The effect of time of day, cloudiness etc.

3.2.8 Ultraviolet

3.2.9 Infrared

[Baas Becking inserted Fig. 3.5.]

3.2.10 Radiation and water

[Baas Becking left this section blank.]

3.2.11 Radiation and the green leaf

[Baas Becking left this section blank.]

3.2.12 Radiation and evaporation

Evaporation in the Australian desert may amount to 30 ml/day, corresponding to an evaporation of 3.0 × 580 = 1,740 calories/cm2 day, or taken, as 14 hours sunshine the solar constant, 2 cal/cm2 minute, would be 100 % utilised! Usually this is not the case, however. In moderate latitudes we attain values ranging from 0.3 to 1.2 ml/day. Still to our surprise in a natural wet country like Holland evaporation seems to exceed precipitation (830 to 750 ml/yr.). Only our high soil-water level saves us from drought!

3.2.13 Summary and conclusions

[Baas Becking left this section blank.]

[The following notes and references are written in ink and therefore probably entered into the manuscript before Baas Becking was in the Utrecht Kriegswehrmachtgefängnis [German army prison in wartime] in July and August 1944.]

Text box 3.1 – Baas Becking notes made prior to writing the manuscript

Protozoa. Glaser and Coria thermal springs Virginia. 34-36 °C, not 39-41 °C.10

Uyemura thermal water Japan. 30-51 °C, Amoeba sp., Vahlkampfia limax, A. radiosa, 36-40 °C, A. verucosa, Chilodonella sp., Lionotus fasciola, 30-56 °C, Oxytricha fallax.11 Dallingen and Drysdale Tetramitus rostratus + 2 others, culture 16-70 °C.12 Efimoff undercooling -9 °C, Paramecium, Frontonia, Colpidium persist, die quickly at –4 °C.13

Andrade, 1934, viscosity 𝜇 = Aec/T, water does not follow below 60 °C, above 60 °C it follows this equation. 14

3.3.1 Introduction

Not only that we have for vital processes a temperature minimum, optimum and maximum (v. Sachs),15 but also in below optimal ranges especially biological reactions are usually highly influenced by temperature. There exist several excellent treatises on this matter. An older by Kanitz (1919) and a comparatively recent treatment by Bělehrádek (1938).16 Usually an enormous anecdotal mass of data is brought together, but this would only come to confirm us about so. We restrict ourselves to the statement of a few generalities, pertinent to the concept of temperature as a factor of the external milieu.

3.3.2 The influence of experiments on chemical reactions

Chemical and biological processes both, it was known to Berthelot,17 are influenced by temperature such that any 10 °C increase in temperature will double or triple the rate of the process. Van ‘t Hoff and Svante Arrhenius have given an empirical expression connecting the intensity of a process (reaction “velocity” with temperature) as;


or, at temperature T1 and T2;


The constant μ/2 is sometimes called the temperature characteristic and is thought to have the dimension of energy (W. Crozier). Unfortunately, the constant is not so very characteristic. Crozier (1924) has tried to find regularity in the μ of different biological reactions.18 All in vain. In physiological reactions the Q10, which is It+10/It = 2-3, decreases with increasing temperature.

3.3.3 The influence on chemical reactions: theory

According to Guldberg and Waage the reaction velocity should be proportional to the number of impacts, such as:19

  • a. Activation. This is proportional to the average velocity of the molecules. It should be proportional to the absolute temperature. This would yield, between 10 and 20 °C a Q10 = 1.03 - 1.04! So, we often think that a certain group of molecules are activated by temperature (extend this?).

  • b. New analysis, of Ohm’s law I = E/R speaks about chemical intensity as a quotient of chemical potential and chemical resistance. Now, the potential is apparently not much influenced by temperature, but the resistance, the internal friction, the viscosity might be! Belehradek.

3.3.4 Influence on diffusion

On several physical processes, temperature has little influence. One of the best known is diffusion, both of gases under liquid or of solute in the solvent, the Q10 being 1.14. It has become a habit in physiology to ascribe processes with a low Q10 frequently to diffusion processes (see Section 4.1.6). Surface tension is another property, fast as density, refractive under that, varies but little with changing temperature.

3.3.5 Photochemical reactions

These are almost never influenced by temperature, beyond the effect expected from thermal agitation of the molecules in the milieu (Q10 = 1.04). There are, of course several weak processes. In the first place those connected with photosynthesis, further those connected with light perception, then the formation of argesterol by ultraviolet, and the introduction of auxin to lumination. The production of light by bacteria is a chemical process and has a high temperature coefficient.

3.3.6 Viscosity methods20

a. Measurement of Brownian movement (Baas Becking, Pekarek). Micro method, based on equation of Einstein Smoluchovski; Baas Becking, Bakhuyzen and Hotelling (1925).21


[𝛥2 = mean squared displacement; R = universal gas constant; T = temperature; 𝜇 = viscosity; 𝜌 = radius particle; N = Avogadro constant; 𝜏 = time interval]

b. Stokes’ law (Heilbrunn, Seifriz, Naber). Falling starter granules, in cell, moving iron particle in magnetic field, falling sphere, or ascending air bubble.22


[Fd = Frictional force; 𝘳 = radius of spherical object; v = flow velocity relative to the object; 𝜇 = viscosity]

c. Poiseuille’s law (Oswald)23


[V = volume of the liquid; r = radius of vessel; t = time; p = change of pressure; 𝜇 = viscosity; l = length of vessel.]

Therefore yield from same tube of two liquids 𝜇1 and 𝜇2, 𝜇1: 𝜇2 = t2 : t1 at constant temperature.

d. Couette method. Two concentric cylinders rotating one inside the other. Seems to be most satisfactory method although the falling bullet, under an angle of 80° is a close second. In the definitive section, topic should be extended.

3.3.7 Viscosity results

For influence of temperature on viscosity of water and of brine, see Geobiology (1934, v. Leeuwen and Baas Becking).24 [Baas Becking inserted Fig. 3.6 that also contained a table in which the viscosity of water as function of temperature was illustrated.]

Now Belehradek (1930)25 called attention to the fact that, when dissolving substances in water, such as sugar, on mixing it with glycol, we may obtain temperature coefficients of any desired magnitude. Now viscosity is shearing force and had nothing whatsoever to do with chemical reaction. Still, it yields this very high Q10. Belehradek looked for an explanation of the high temperature sensitivity of vital processes in the variable viscosity of the colloidal protoplasm.

3.3.8 Viscosity interpretation

Da Costa d’Andrade (1934) has succeeded to prove, from thermodynamic considerations the expression:26


in which A and C are constants [and T = absolute temperature and 𝜇 = dynamic viscosity]. For 𝜇1/𝜇2 we obtain:


and we see that this is the inverse of the Arrhenius expression. If a Nernst analogue:


applies and E is only a little influenced by temperature, one would account for I = f(T) becomes R, and the chemical resistance is highly influenced by T.

3.3.9 Physiological reaction

Generally only if temperature be a limiting factor we may see the temperature effect (see also Section 5.4).

3.3.10 Protoplasmic streaming

Hille Ris Lambers (1922) has shown that there exists a linear relation between temperature and velocity of protoplasmic steaming in Nitella.27 Botteltier (1935) working with oat seedlings (coleoptiles) found no temperature influence below 17 °C.28 Above that temperature the curve was linear. Baas Becking, Hotelling and van Sande Bakhuyzen have shown, by means of the measurement of particles in Brownian movement in Spyrogyra protoplasm, that micro currents exist and that their velocity is also a factor of temperature.29

3.3.11 Photosynthesis

Here v.d. Honert (1928) has done the classical work with the alga Hormidium.30

1. Diffusion of CO2 (Q10 = 1.17).

2. Photochemical process (Q10 = 1.04).

3. Chemical or dark process (Q10 = 2-3).

3.3.12 Tropisms

[Baas Becking left this section blank.]

3.3.13 Respiration

[Baas Becking left this section blank.]

3.3.14 Development

[Baas Becking left this section blank.]

3.3.15 The natural limits of the temperature milieu

[Baas Becking left this section blank.]

3.3.16 Thermal behaviour of milieu

(A. von Kaleczinsky).31

As brines have a lower specific heat than pure water, and as their vapour pressure, and consequently their evaporation intensity is less. They tend to heat up much more than freshwater. Temperature of 38 °C were observed by the author in Portugal in a saturated brine. In Bean Lake (Medve Lake) in Hungary, a layer of freshwater floating on the brine blankets it to such an extent that the brine heats up to more than 75 °C. The establishment of a bathing beach according to v. Kaleczinsky, distributed the phenomenon. Still, it might be feasible, as he suggested, to use some such an arrangement for the accumulation of solar energy.

(This really belongs under brines in Section 3.13.5).

3.3.17 Summary and conclusions

[Baas Becking left this section blank.]

3.4.1 Introduction

Apart from radiation and temperature the physical milieu has been very imperfectly studied. While aware of the fact that there is more between heaven and earth than is dreamt of in physiology, all sorts of physical causes have been ascribed to as many effects. Still, the result has been meagre. Promising would be the investigation of material or even (suspensions) and of high pressures (supposing that piezochemistry of aqueous systems were further developed).32 Of the other physical factors, cosmic radiation, atmospheric electricity and the like, it seems best to relegate these to a box in which we stored our magic waste and our terrestrial rags.

3.4.2 Pressure

Water has a very low coefficient of compressibility although its space lattice (tridymite below 4 °C, quartdymite above 4 °C) does not exhibit the cases of closest packing. Pressure therefore, will but little change the aqueous phase of the living cell. Biological effects of pressure are mainly related to gases which, following the law of Henry decrease or increase their solubility in water proportional to the pressure. (Mountain sickness, diver’s sickness, caisson disease). The law of Dubois-Reymond states that the rate of change in the intensity of a stimulus determines the intensity of the reaction.33 This is also the case with pressure, where according to Henry’s law, the solubility of gases is a function of the pressure and pressure changes may therefore, cause gases to escape from cells and thereby damage them (study on deep sea organisms). Shelford (Ecology) mentions a man’s death from various species of flies after a sudden barometric depression previous to a storm.

3.4.3 Material waves

In the tropics a well known mode of fishing is by means of dynamite detonation under water. Quite large fishes are stunned, or even die by the material waves originated. Supersonic waves, originated by piezo quartz leave, when of sufficient amplitude, a lethal effect upon protozoa. Their disintegration may be observed immediately after application.

Other electromagnetic waves. The effect of ultraviolet is well known. Infrared (haute frequency) so often changes into heat, as water has intense absorption on the Infrared. Radium’s deleterious effects of X-rays on cells is well known. Sublethal dose may in induce mutations. It has been claimed that ultra-shortwave radio may have a lethal effect on membranes.

3.4.4 Atmospheric electricity

(W. Pfeffer,34 A. Stoppel,35 A. Dezovica [?], T. Kleinhoonte,36 F. Blackman).37

The periodic movement of leaves (as Canavaliaensiformis) from the periodic movement of leaf-inhabiting animals has raised the question behind this rhythm. Apparently not closely connected to a diurnal rhythm, might not be dictated by variations in atmosphere electricity, the gradient of which (± 100 volt/metre) may be easily measured by mean of an electroscope. The outcome of the very controversial matter has not led to a satisfactory general conclusion (Expand!)

3.4.5 Cosmic radiation

Well known are the investigations of Muller on mutation rates of Drosophila.38 It seemed that the rate was less in deep mine pits where the Geiger counter registered a much lower increase of cosmic radiation then at the surface of the earth. It is also claimed (Bohr) that effects have been obtained on sea urchin eggs.

3.4.6 So called mitogenetic or Gurwitsch-radiation39

This should be augmented by all sorts of biological material, such as ground frog larvae, but especially spear frogs. It should be ultraviolet and have a profound effect on the number of cell divisions of a detector organism.40 Unfortunately, a careful statistical investigation of the bacterial plate method of detection has shown that we have to relegate this theory to the realm of the “Wünschträume” (see further monograph of Rahn).41

Eau, - - - tu es la vie”, de St. Exupéry, Terre des Hommes.

[Baas Becking inserted Table 3.3 in which the properties of water were summarised.]

3.5.1 Introduction

Water is a most unusual substance. While a substance like methane, M.W. = 16 or a substance like NH3, M.W. = 17, have melting points far below zero (-70 to -80 °C) water, with its small molecular M.W. = 18, is a liquid at average terrestrial temperature. In nearly all of its physical properties it shows the same extreme character, its dielectric constant, its ionisation, its dipole character, its specific heat. We should not be amazed to find authors like the Rev. Whewell, who in his Bridgewater Treatises wrote paeans on this topic in order to show that this substance, the regulator of temperature and the regulator of life upon this planet, is placed here by special providence to enable us to enjoy the earth.42 A little more modesty allows us to see that life, as we know it, is counterpart of the water and the question whether water is here because of life or life is here because of water seems theological rather than scientific. We shall revert to this problem in Section 3 and in Section 5.

3.5.2 Physical properties

MP and BP, vapour kinetics. The whole range between zero and 100 °C is available for life. In this range most physical and chemical properties change gradually. MP and BP are influenced by dissolved substances, according to rules given by van ‘t Hoff. The rather high vapour pressure makes for effective use of absorbed radiation.

3.5.3 Physical properties: specific gravity

Spring and fall mixing of freshwater masses (Fig. 3.7). Pure water has an optimal density at 3.98 °C. Freshwater of this temperature is therefore the heaviest, and it will mix if the depth of a natural body of water be great, the deepest layer (hypolimnion) shall have this temperature. Later we shall revert to this phenomenon, when natural waters are described. In seawater (3.5 % salts), the temperature of maximal density is below zero and even below the freezing point of seawater, so that this factor cannot play a role in the vertical mixing. As in ocean water also salinity exerts its influence, vertical as well as horizontal currents may be predicted, salinity and temperature, being known, from the so called Bjerkness-theorem.43 Discussion of which would lead us too far.

3.5.4 Radiation

Water has usually a high absorption in the infrared, with distant bands (plate after Ellis). Aschkinass (1895) has determined the absorption coefficients for various wavelengths.44 The absorption decreases towards the blue end of the spectrum, the “blueness” of water is due to this fact and also connected with light dispersion (Rayleigh phenomenon), which is the cause of the blueness of the sea. Water is fairly transparent to ultraviolet rays.45 The opacity for these wavelengths in seawater is caused, according to Hulburt, by the magnesium salts present.46

3.5.5 Viscosity

𝜇 = 0.01 poises at room temperature, with a temperature coefficient of 1.4. Winter and summer viscosity are, therefore quite different, a fact which has an important bearing upon the flotation power of plankton (Woltereck, Kizaki, Daphnia).47 The temperature coefficient increases with the amount and the nature of dissolved substances (Baas Becking, v. Leeuwen, Belehradek).48 A solution of 1 N cane sugar has already very high aqueous effluent. Spurious thermophily may result. The bearing of this phenomenon on temperature effects is discussed elsewhere, Correns (1939, p. 119).49

3.5.6 Surface tension

(2 ergs/cm2, an extreme value again). This surface tension is lowered by traces of dissolved substances, especially by lipophilic substances. Czapek has based his theory of permeability on the fact that many permeating substances are able to lower the surface tension of water.50 Substances, which lower the surface tension, accumulate at interfaces, and so the lipophilic outer layer of liquid protoplasm may be accounted for. After diatom epidemics the surface tension of the ocean may be lowered and foam formation much favoured. After spring and autumn blooms of diatoms the phenomenon may be regularly observed.

3.5.7 Dielectric constant

𝜀 = 81 is by far the highest known, followed by liquid ammonia with 𝜀 = 67. Keller has elaborated a theory of vital staining,51 which takes into account changes in the value of the constant. According to the law of Lorentz-Lorenz the constant is related to the refractive angle which in water has a very low value 𝜀p25 = 1.334, only deuterium oxide being lower as a liquid.

3.5.8 Thermal properties

Water has a very high heat of fusion (80 cal) and a remarkably high heat of evaporation (580 cal at room temperature). This last value is the cause of the heat regulation due, on this planet, to water evaporation. The high specific heat, which does not fit Dulong and Petit’s rule,52 makes water an ideal heat accumulator, that accumulates and thermostats in one the 2/9 of the earth’s surface which are covered with water, actually guards against overheating and too rapid cooling. Apart from volcanic action the highest temperature on record in aqueous milieu is [ca. 35 °C] (Persian Gulf) on land 84.6 °C in the African desert. The author measured 31 °C in the Pacific near Corinto Nicaragua July 1928,53 and 62 °C on a black sand of Verlaten Eiland, near Krakatou, Sunda Strait, October 1939.

3.5.9 Cohesion

Water shows an enormous cohesion, probably due to the semi-crystalline lattice in which its impermeable molecules group themselves and also their tendency to form chains (see Section 3.5.3). A capillary water column of several hundred metres still will not break. The theory of Atkins of the water movement in woods, the so called cohesion theory, makes use of these uninterrupted “water fibres”, which evaporate at the top and are replenished from below.54 The cohesion process also accounts for the ease with which water, with only a little colloid (0.2 % agar) will form a solid substance.

The impermeability is very low, although the lattice structure does not represent closest packing.

3.5.10 Chemical properties

Water reacts with several metals, forming the molecule of hydrogen:


The chemical reaction of both inorganic and organic compounds seem often to be excluded in sufficiently water-free systems. With carbides it forms acetylene:


It is able to saponify ester: 55


An enormous range of substances, polar and non-polar, are soluble in water. Many molecules orient themselves in water (spreading). Water is also a universal catalyst.

3.5.11 The ionisation

The ionic product of water Kn is, at room temperature 7 × 10-14 (Kohlrausch), influenced by the temperature. The hydrogen ion H+ is nowadays conceived as hydrated OH3+. Neutral point exists when


and is called pH. pH at neutral point is therefore 7.0. The oxygen ion O2-,as supposed by Nernst, may exist although the second dissociation constant of water will be exceedingly small.

3.5.12 The isotopes

Deuterium, M.W. = 2, was discovered in 1935 by Urey.56 D2O is a liquid very much like water, showing even anomalous expansion and maximum density at 3.5 °C. It solidifies at +3 °C, it boils at 101 °C, its refractive index is, for a liquid, is exceedingly low Nd15 = 1.29. D2O was originally prepared from the liquid in a long used electrolytic bath, it was, therefore, originally contaminated with nickel. D2O is present 1:5000 in natural waters. It does not accumulate in desert waters as Prof. P. Cohen had the kindness to analyse the brine of Searles Lake, Nevada57 which, however, showed no increase! Physiological processes seem on the whole, retarded in D2O, although the effect is often slight. More important is the use of D2O in the Harvey technique of marked atoms to establish the role of water in physiological processes.58 This technique has contributed much to elucidate the fact that the quintessence of metabolisation might well be the reaction


It has been said metaphorically that hydrogen is the fuel of living things. To the author this dictum is more than a metaphor.

3.5.13 The structure

Bernal and Fowler (1933) have shown that ice, at a too low temperature, and water below the point of maximum density, has a lattice structure much like tridymite (SiO2).59 Above 4 °C, up to ±200 °C, the lattice structure is closer, like quartzite, while the crystalline structure is reached between 200 °C and the critical point at 314 °C. There is evidence of chain formation (Fig. 3.8), but not so far as to warrant older assumptions of Armstrong (1908) according to which there should exist a tri-di-and mono- hybrid, the former in ice, the latter in steam.60 Water is, of course, a dipole μ = 18 × 10-18. The distances in the lattice are 2.9 × 10-8A, 1.4 × 10-8 Å, and the valency angle 104-106°.

3.5.14 Theories of Barnes

Barnes, father and son,61 and Vouk have claimed that water which has been recently obtained from ice has other properties then water obtained from steam.62 The former exerts a beneficial effect upon organisms. The latter shows a deleterious influence. Repetition of their experiments with the algae Spirogira, and careful viscosity measurements of water of known previous history have convinced me that there is such effect. Vouk and recently Radermacher claim that water, autoclaved at a high temperature (“fervorised water”) has a beneficial effect, as compared to “non-fervorised” water.63 Boezeman has repeated the experiments in my laboratory with positive results. I am unable to account for the curious phenomenon, which is not due to trace elements, having made use of quartz throughout.

3.5.15 Heat of formation of organic compounds of acid and bases64

The heat of formation of water, from the elements, amounts to 56,500 calories. The heat of formation from the ions is 28,000 cal. This is also the heat of neutralisation, when a base is titrated by an acid




According to the values given by L. Pauling for heat of formation of organic radicals the heat of formation of an organic compound does not change if its H and the number of its H and O atoms be increased or decreased in a ratio 2:1 as in H2O (see Plate 3.1).65 From this plate it may be seen which processes require energy, and by which energy is liberated.

See also Figure 6.5, Figure 6.6 and Table 6.2.

3.5.16 The respiratory quotient

Complete combustion of an organic compound


yields for the respiratory quotient RQ = a/x. Now:


From this it follows, that addition, or subtraction of H2O + a molecules will not change the RQ of the compound. From the rule found for the heat of formation of organic compounds we may derive directly H × RQ = heat = 120,000 cal/at c (see Plate 3.2). In incomplete combustion or in more complex reactions the relation, however, does not hold.

[The transcript of the notes in the plate reads as follows:]


The degree of reduction of a CHO compound may be expressed as






RQ × 𝛥H = 120 kcal

30 R = 𝛥H

𝛥H = heat of combustion

RQ = respiratory quotient

𝛥H is a multiple of the OH dissociation energy which is 56,000/2 = 18,000 cal.

The whole 𝛥H is dependent upon water!

3.5.17 Physiological properties: temperature

The impact of the water molecules in thermal agitation may cause small objects (ϕ < 10ρ) to perform irregular, microscopically observable, motions (Brownian movement). Here the average deviation square of such a particle in time 𝜏,


In which 𝛥2 = mean squared displacement; R = universal gas constant; T = temperature; 𝜇 = viscosity of the milieu; 𝜌 = radius particle; N = Avogadro constant; 𝜏 = time interval.

By means of this equation the author, with v.d. Sande Bakhuyzen, and later Pekarek, have shown that protoplasm, in certain instances, behaves almost like a dilute aqueous solution. See also Section

3.5.18 Water of metabolism

It has been shown by Beyer [?] that the water content of the clothes moth and of the wax moth is entirely derived from metabolic water, that is water derived from dehydrogenation and oxidation of organic substances, e.g., when sugar is metabolised.


It is safe to assume that there are many organisms, which provide themselves with water in this way, for example the petroleum fly Psilopa petrolei (Thorpe, 1930).68 Furthermore it seems safe to infer that part of the water present in every organism may be considered as metabolic water.

3.5.19 The essence of metabolism

We recall an old experiment of Wieland a good model of catabolism;69 the oxidation of CO – CO2 in aqueous solution + Al catalyst.

We find:


We find a hydration, a hydrogen generation and a hydrogen acceptance, the latter usually as the formation of water. As such we suggest conceive the last act of metabolism, is acceptance of metabolic hydrogen by oxygen. Inversely, we might consider photosynthesis as a photolysis of water; the hydrogen evolved being accepted by carbon dioxide to form organic compound: photolysis and formation of water lie at the base of all metabolism (heat of formation from the elements 56,500 calories).

3.5.20 Swelling pressure (osmotic pressure)

Osmotic phenomena may generate pressures of several hundreds of atmospheres, due to the one sided impact of dissolved particles delivered upon a membrane, the amount of energy liberated doing swelling of colloids, however, is such that the swelling pressure is measured by thousands of atmospheres! (colloid pressure, Energia, Graham).70 As shall be argued later more extensively, all water intake by living things is regulated by one or both effects. The author, in a lecture for the Nat. Academy at San Francisco in 1929 has developed a picture of both pressures (Fig. 3.9).71

3.5.21 Free and bound water72

Gortner has in the last decennia developed the concept of bound water which is, essentially similar to that depicted under swelling pressure.73 It is not, or is only partially, available for osmotic and chemical action. It may be determined by the expected and observed expansion at freezing of solutions, expected and observed contraction at the fusion of solutions, action on cobalt salts or measurement of freezing parts or of vapour pressures. In plant cells the amount of bound water shows a relation to drought and to frost resistance (Newton, Scarth and co-writers).74 By measuring the volume of a plant vacuole in solutions of varying hypertonicity the deviation of the Boyle’s law PV = CT measures the bound water as a van der Waals correction P (V-b) = CT. This may be the only reliable way to measure bound water, which, according to some authors, is in no way different from free water.

3.5.22 Summary and conclusions

This description of the properties of water is far from complete. Moreover, the advancement of science adds new data almost every year. We did not speak of the role of water in electrochemistry, in colloid chemistry. We did not mention the various forms of ice. Raman spectra and X-ray data were also omitted. Still the picture given will suffice to show the extraordinary, and complicated nature of this most marvellous of terrestrial substances. If any substance on earth is the counter mould, the resonator, the very core of life, it is water. Paramount not only as a biological substance, but also as the central compound of chemistry, and one of the most important factors in geology, it is the veritable carrier of things geobiological and geochemical. Few, if any substances (perhaps apart from liquid ammonia) could, at any place in the cosmos, fulfil a comparable role.

3.6.1 Introduction

The gases that are dissolved in water may be roughly divided into two groups, which differ greatly as to their solubility. The first group, comprising carbon dioxide, ammonia and hydrogen sulphide, react with the water and are, consequently more soluble in water, while the other group, represented by oxygen, nitrogen, hydrogen do not associate themselves chemically with the water. Both groups are, however, subject to Henry’s law: the amount of the gas dissolved is proportional to the pressure of that gas, equilibria however, are very slow to establish themselves. Supersaturation with oxygen of 300 % may scarcely occur, while it takes 24 hours mechanical shaking to bring water into equilibrium with a gas as CO2. The swiftness with which equilibria are established has an important bearing on hydrobiology, as a water may show something of its history by the composition of its gases.

3.6.2 Highly soluble gases: CO2

[Baas Becking inserted Fig. 3.10, ratio of carbonic acid and bicarbonate and carbonate as a function of the various acidity levels.]75

Part of CO2 dissolved on water from [H2CO3] (see also Section 4.3.2). This H2CO3 is dissociated




In order to find the proportions of bicarbonate, carbonate and carbonic acid [follows formulae as in Geobiologie, 1934]. When we set the total amount of carbonic acid as equal to 100, it can be deduced that:





Sedimentation, photosynthesis, respiration, changes in pH influence the concentrations remarkably. Changes in the CO2 and its dissociation are treated in this book in Section 4.6, Photosynthons. Of course, CO2 is, apart from its geochemical importance, the most important nonorganic biological compound.

3.6.3 NH3 solubility

[NH3], it forms immediately the highly oxidised base NH4OH. In nature NH3 is found in volcanic exhalations and around places where protein or urea is decomposed. Pasteur has discovered the Urobacilli and the Micrococci,76 organisms able to decompose urea according to


In natural water the content is low, especially when the water is aerated. Nitrobacter oxidises NH4+ to NO2 (see Section 4.7, Chemosyntonts).

3.6.4 H2S

The author [Baas Becking], and van Niel (1932) and Pop (1936) have called attention to the fact that this highly soluble gas shows great similarity to CO2 as the substances show two dissociation stages k1 being [9.6] × 10-8 and k2 [1.3] × 10-13 [mol.L-1],77 sulphydryl SH- (= the univalent radical SH is the sulphur analogue of hydroxyl and constitutes the thiol group) and sulphite S2- on being formed respectively.78 Van Niel showed that undissociated H2S is probably toxic to purple sulphur bacteria, while Pop had a similar experience with unicellular green algae. With increasing acidity, the toxic effect mounts rapidly although H2S is quickly oxidised by oxygen. The lack of an equilibrium condition makes it possible to find oxygen and hydrogen sulphide in same sample. H2S originates chiefly from sulphate reduction and certainly not from the “pacification of protein”, as even various authors (Correns, 1939) claim.79 See also Section 7.8.8, Sulphur cycle.

3.6.5 SO2

In industrial smoke much SO2 is usually present, if not removed by Cottrell apparatus or by previous washing. It is quite soluble in water, where it forms sulphurous acid HSO3.80 It seems to exert a fatal action on the photosynthetic apparatus of green cells, and forms probably a rather stable compound with chlorophyll, even in low concentrations. In higher concentrations it causes actual burning or bleaching. In the neighbourhood of volcanoes SO2 is very commonly occurring. On the remarkable occurrence of sulphatic plants (von Faber, 1925).81 Highly susceptible, at the other hand, are pines and oaks, strawberries and beets. They are veritable test organisms for industrial smelter damage.

3.6.6 Slightly soluble gases: H2 solubility

Generated by volcanoes. Von Wolzogen Kühr pointed out one interesting way of H2 generation by metallic iron such as water pipes.82 This iron would form, with the surrounding soil solution as electric element, where the iron would yield electrons to react with hydrogen ions, forming atomic hydrogen according to:


Hydrogen is further set free in a great many osmotic bacterial reactions. It easily enters the cycle again, being accepted by a great many organisms, especially the hydrogen organisms, Hydrogenomonas ruhlandii:


e being used to reduce etc.83

3.6.7 CH4 an d CO, solubility

Methane occurs in volcanic exhalations but its chief source is the anaerobic cellular fermentation, by which enormous amounts of illuminating gas disappear in the atmosphere (consequently the flatus of ruminants contains large quantities of methane, methane formed in sheep at 40 litre/day!), “source-gas” = biogas of the farmer in N. Holland. At Groningen city waste is used to make gas. It is probably mostly decarboxylation of fatty acid, however Lieske (1929) showed that CO may be reduced anaerobically to CH4!84 The CH4 may be oxidised by autotrophs to CO2, or anaerobically transfer H (Gailey). CO originates probably from HCOH and occurs in the bladders of the giant brown seaweed Nereocystis lütkeana (5 %) (Hoagland, 1915).85

3.6.8 O2 solubility

It is misleading to express O2 as cc/L or mg/L, as this is a function of temperature. Much better is % saturation! Probably originated by photosynthesis action from water. With H2 and CO2, the most important biological gas. Accepted by specific enzymes (yellow enzyme of Warburg, red haemo and Ca oxide),86 it reacts with the hydrogen as the substrate. Water may become easily saturated in mg/L up to 300 % (the same is true of CaCO3, also 300 %, see Wattenberg, 1938, Meteor).87

3.6.9 N2 solubility

79 % of atmosphere. Enters into the cycle only through 3 bacteria and bluegreens, (molybdenum catalyst) to form NH3. Equilibrium with water slowly obtained. It may be used to determine origin of natural water, using solubility as a function of temperature. Nitrogen is also formed by nitrate reduction, which is active even in highly saturated brines. In seawater it shows less activity, especially in the aerated surface water.

3.6.10 CH2 = CH2 ethylene

Biogene of biological origin. Ripening of fruits (Molisch, F. Denny). Technically prepared from alcohol by means of phosphine acid, PH3. Molisch discovered (1937) the effect of the emanation of ripe apples upon the growth of tomatoes.88 Denny (1924) recognised acetylene as active (6 parts per 106) in bleaching celery, ripening of bananas (citrus fruit).89 Nicolai and Baas Becking (1935) found that it could ferment tobacco.90 Gouwentak (1941) proved that it could break dormancy in buds.91

See further Section 7.2, Ergones on enzymes. In Plate 3.3 on graphical chemistry, the position of the gas is shown to be unique. [Ethylene is represented as “i”.]

[Baas Becking (1959) described the equilateral triangular plot with compounds C – 4H - 2O in more detail:]

In order to represent changes in composition of organic matter (simplifying the processes to changes in C, H, and O) we may represent the relations in a triangular diagram (Baas Becking, 1947b) if the corners represent C, 4H, and 2O respectively. The point representing CO2 will be halfway on the C–2O line, while CH4 and H2O occupy analogous positions on the other sides. It is easy to show that all substances with a reduction level of O will be situated on the line H2O - CO2, all substances with a reduction level 8 on the line H2O - CH, while the line C - H2O (“carbo – hydrate”) shows the reduction level 4.

A bundle of lines passing through H2O represent (de)hydrations, a bundle through 4H represent (de)hydrogenations, while the bundle through CO2 represent (de)carboxylations and that through 2O (de)oxygenations.

3.6.11 Water vapour

In the atmosphere up to 17.28 g/litre, has great effect upon thermal properties of atmosphere, upon wind formation and radiation, blanketing. [Baas Becking referred to table ‘Composition of Atmosphere at various levels’ according to Humphreys (1926) in Critical Tables I (p. 393).]92

Water vapour may be absorbed by various organisms. Enters and leaves every leaf. See further Section 5.10.4.

3.6.12 Other gases and summary

It is a remarkable fact that the organisms occurring in the black mud, in hot springs and those in strong brines should show many points in common. It may be that the dictating factor here is the oxygen, or rather the absence of oxygen. The solubility of the gas in weak brines (saturated NaCl) is only 1/9 of that in freshwater while at high temperatures the solubility is also reduced materially. On the black mud the oxygen tension is practically zero. (For functions of oxygen see Section 5.10.12). The work of E. Reuter however tends to show that at least for higher plants, a diminution of the oxygen pressure to 1/9 does not materially return the vital functions.95 This finding is corroborated by the data obtained with lower forms, when the oxygen starts to be limiting factor at very low pressures. Phylogenetically we need not wonder at this, if we adhere to the theory of V.M. Goldschmidt concerning the photosynthetic origin of the atmosphere oxygen. Extreme anaerobic we might only expect in the most recent forms, the so called “higher” plants and animals.

3.7.1 Introduction

The chief causes of acidity and alkalinity in the natural milieu are the carbonic acid, the sulphuric and hydrochloric acids, and their dissociation and reduction products, organic acids play a subordinate role.

3.7.2 CO2 equilibrium

The equation developed in Section 3.6.2 may be extended by the concept of excess base.96 If we write:


[B] represents the excess base as its order of magnitude is usually much higher than [H+] we may write the equation (Johnston):97


Continuing Johnston’s equation with those derived in Section 3.6.2 (Michaelis),98 we get:

in which kw = dissociation [constant] of water [= 1.0 × 10-14], or as 1/2k1k2 is very small


For B = 0 and for CO2 = 10-4, pH = 5.8. Titrating the water with 0.01 HCl with methyl orange or methyl acid to endpoint ±pH 5 gives B. For seawater this is 25 × 10-3. Borates may influence the result slightly.

3.7.3 Sulphate and sulphides

Wattenberg and Timmerman (1936) have investigated the condition of CO2 in seawater, especially in relation to lime deposition. Increase in [H+] will cause CaCO3 (KCaCO3 ∼10-8) to dissolve and inversely.

Increase of temperature changes K2 more than K1, hence an increase in CO32 pressure causes an increase in solubility, and increase in [H+]. Pure NaCl increased the solubility of CaCO3, which is counteracted in seawater by other ions. Taken all in all the influences tend to counteract one another, so that the solubility of CaCO3 in seawater is the same as that in freshwater (±30 × concentration of CO3 in air).

See further Section 3.5.2, Swelling pressure, Section 6.6.5, Lime deposition and Section 7.8.8, Sulphur cycle. The original paper by Wattenberg and Timmerman, Ann. Hydrog. Berlin 64 (1936), p. 23, should be consulted.99

3.7.4 Ammonia and nitrates

[Baas Becking left this section blank.]

3.7.5 Borates and phosphate

[Baas Becking left this section blank.]

3.7.6 Hydroxides

[Baas Becking left this section blank.]

3.7.7 Solubility of cations and anions

[Baas Becking inserted Fig. 3.11.]

3.7.8 Origin of acid in bog water

[Baas Becking left this section blank.]

3.7.9 Summary and conclusions

[Baas Becking left this section blank.]

3.8.1 Introduction

We shall only give a brief summary of those elements that directly concern living matter and enter into dealings with living matter. We shall conclude the so called minimum elements; they are dealt with in Section 5.8, Minimum Elements. Of these “primary” biogenic elements we name fourteen, all of low atomic number (1-28), six of them metals. According to several authors, this number is too high, we should exclude Na, Al and Si, it is even claimed that certain organisms may develop without calcium, however, experiments in this direction being extremely difficult, it is better to reserve judgment in this case. Most of the mineralogical and geochemical information has been taken from Clarke’s (1916) well known work.

Bioelements: H, C, N, O, S, P, Cl, Na, K, Cu, Mg, Fe, Al, Si.

3.8.2 Hydrogen

22 % of the lithosphere, 10.67 % of hydrosphere, overige [Dutch word for ‘other’] 0.95 %. In all rocks, either as included moisture, or as hydroxyl. With carbon the most important element in organic substances, where it functions as the universal fuel substance. Frequent in a native state in rocks, in volcanic exhalations, and formed by the reduction of organic matter or the ionisation of metallic iron.

3.8.3 Carbon

19 % of the lithosphere, 0.002 % of the hydrosphere, average 0.18 %. Characteristic of all organic compounds, native as graphite (laminar lattice) and diamond (tetragonal lattice) or as coal (amorphous). Carbon dioxide 0.03 % of atmosphere air. Natural gas, petroleum and paraffin are essentially hydrocarbons. Carbonic acid is in natural waters, enormous sedimentary rock masses of calx [= lime] to aragonite CaCO3 or dolomite to CaMg(CO3)2, siderite FeCO3. In magmatic silicates only as cancrinite Al3Na4HCSi3O15. Methane CH4 in volcanic exhalations is found by cellulose fermentation. See further Section 7.8.6, Carbon cycle.

3.8.4 Nitrogen

Nitrogen is practically confined to the atmosphere (79 %), only 0.03 % of the known terrestrial matter. Of primary importance in organic matter, especially in proteins. Nitrogen is also a constituent of the important class of compounds known as porphins (chlorophyll, haemoglobin, enzymes). Volcanic water contains ammoniac compounds, electric storms may form some nitric acid, but all the rest is biogenic including the nitrate beds, as in Chile. Several microbes are able to reduce atmospheric nitrogen. Microbes and green plants are able to reduce nitrate to ammonia. See further Section 7.8.7, Nitrogen cycle.

3.8.5 Oxygen

47.33 % lithosphere, 85.79 % hydrosphere, average 50.02 %. According to Goldschmidt the earth crust is a “crystalline oxygen lattice with other elements interspersed”; oxysphere (Goldschmidt, see p. 36). The most abundant of elements, forming more than one half of the terrestrial elements. In the free state it constitutes about one fifth of the atmosphere, and in water it is “the chief element of the ocean” (Clarke, 1916, p. 18). All the important rocks contain ±50 % oxygen. The atmospheric oxygen probably is derived from the photosynthetic activity of green plants (Kelvin, Goldschmidt), which is the analysis of water into its elements. Rocks do not contain oxygen carriers such as haemoglobin and haemocyanin. See further Section 5.10.11, Oxido-reductions, oxygen.

3.8.6 Sulphur

0.12 % of lithosphere, 0.09 % of hydrosphere, average 0.11 %. Native (e.g., Girgenti, Sicily, W. Texas, Java), as sulphides, especially those of iron FeS (hydrotroilite), and FeS2 (pyrite, marcasite and meinicovite). In the ocean as sulphate mainly, further gypsum CaSO4.2aq and anhydrite CaSO4. Sulphides and sulphate in volcanic deposits, and further formed by microbial reduction of sulphates. In igneous rocks as hauynite Al3Na3SSi3O16 [= Na3Ca(Si3Al3)O12(SO4)] and nosean Al3Na5SS13O16 [= Na8Al6Si6O24(SO4)·(H2O)]. Abundant in olia, petroleum, alky sulphides, also in coal. A primary biological element, particularly important in the amino acids cysteine, cystine and methionin, and as such an integral element in hair and horn. This reduced form of sulphur is made by green plants from sulphates, which are the only form of sulphur that the plant can use. Further in the plant as thiocyanate (mustard oil C3H3-CNS) as sulphide (mercaptane e.g., C4H9SH in Lysichiton). In the animal body in chondria paired sulphates. See further Section 7.8.8, Sulphur cycle. In sulphur bacteria rhombic sulphur and formation of sulphuric acid.

3.8.7 Phosphorus

0.0011 % of known terrestrial matter. In meteoric rock as phosphine PH3, otherwise always as phosphate. Chief minerals are the apatites Ca5(PO4) F and Ca5(PO4)Cl (magmatic) other minerals all of biological origin as P is important part of many crustacean shells (Lingula, 91 %) and of bone. From such phosphates are derived phosphoric increments of a deep sea, containing up to 24 % P2O5, the blue vivianite from our marshes Fe3P2O8.8H2O, the several species of guano phosphate etc. Living matter is probably unable to reduce the phosphate to phosphine. Phosphate occurs in living matter chiefly in the lecitinoids and in the nucleic acids. Absorption by green plants as H2PO4- ion.

3.8.8 Sodium

2.46 % of the lithosphere, 1.14 % hydrogen, average 2.36 %. In magmatic rock in many feldspar such as albite NaAlSi3O8, nephelines such as aplite NaAlSiO4, pyroxenes such as aegirine NaFeSi2O6. Abundant in rock salt, halite NaCl, further as a playa deposit trona Na2CO3.NaHCO3.2H2O, soda nitre in Chilian caliche. In nearly all natural waters, accumulated in the ocean as chloride dispersed in the atmosphere (cyclic salt). Probably necessary for animals and certain plants, Antagonist calcium.

3.8.9 Potassium

2.46 % of the lithosphere, 0.04 % of hydrosphere, average 2.28 %. In magmatic rock chiefly in feldspar such as orthoclase KAlSi3O8, mica’s such as muscovite Al3KH2Si3O12 and leucite KAlSi2O4. Nearly all terrestrial water contains it, which is early exchanged by zeolite action. Saline beds near Stanford, Mülhausen and from Searles Lake, California. Kelp is an abandoned source. Accumulated also by higher plants. The most important vital metal, exchanged activity by cell and environment, chiefly as K2HPO4.

3.8.10 Calcium

3.47 % of the lithosphere, 0.05 % hydrosphere, average 3.22 %. As sulphide in meteorites, in magmatic rock anorthite CaAl2Si2O8, garnet Ca3Al2Si3O12, further epidote, amphibole pyroxenes and scapolite. Fluorspar CaF2 and apatite Ca(PO4)3. As carbonate e.g., in calcite, aragonite and dolomite. As sulphate in gypsum and anhydrite. A very important biogenic metal and closely connected with cyclic biological phenomena. In bones, teeth and carapaces, in a great many plants preponderantly as lime.

3.8.11 Chlorine

0.06 % of lithosphere, 2.07 % of hydrosphere, average 0.20 %. In magmatic minerals such as sodalite Al3Na4Si3O12Cl and the scapolites. Further in halite, from oceanic deposits and the K salt carnallite KClMgCl2.6H2O. Free Cl2 and hydrochloric acid in volcanic emanations. In the atmosphere oceanic NaCl. FeCl3 in meteorites. The chief cause of the acidity of sphagnum bogs (Baas Becking and Nicolai, 1934; Thompson et al., 1927).100 Necessary for animals, in known 0.6-0.9 % NaCl. Free chlorine (?) in the stomach of mammals. Cl- ion is physiologically rather inert. See sodium.

3.8.12 Iron

4.5 % of the lithosphere, average 4.18 %. Next to aluminium the most abundant metal; native iron, however, is rare. In practically all rocks, particularly in amphiboles, pyroxenes, olivines and micas. In seawater as FeF3, oxide magnetite Fe3O4 and haematite Fe2O3 and FeO. As hydroxides (partly bacterial in formation) limonite 2Fe2O3.3H2O, further tungite, goethite, xanthosidentite and chimentite. Glauconite, possibly coprolite of echinoderms,, as sulphides FeS hydrotroilite, FeS2 pyrite and marcasite, FeCO3 siderite besides a great many silicates, phosphates etc.

Functions as very important biological metal is coupled to its variable valency. Integral part of many enzymes and red blood pigment, in porphines. At high pH is soluble enough to cause agricultural troubles (citrus, peas, chloriosis). At low pH so soluble that soils may become depleted (podsol). Tropical weathering of soil causes red earth later to be found.101

In geosphere [?] 7.3 % Fe2O3 (Clarke, 1916), oceanic seawater 1.9-9.6 %, rivers <1 mg/L, ocean 1-10 𝛾/L [10-6 g/L].


Water in equation PO2 = 0.206. For PO2 = 1.7 × 10-29 (dissociation water vapour at 17 °C) we get more iron in solution.

[Baas Becking inserted Figs 3.12 and 3.13.]

See also Cooper (1935, 1937): Some conditions governing the solubility of iron, Proc Roy SocLondon B, 124, p. 299 (1937); Iron in the sea and in marine plankton. Proc Roy SocLondon 118, p. 419 (1935).102 [See Fig. 3.14.]

High acidity and low pO2 make iron more soluble. The articles of Cooper should be consulted in the original. In seawater the iron is present as practically undissociated FeF3. The older literature mentions ferrates, most probably these compounds do not exist. In the considerations of Cooper, no mention is made of ferrites and ferrates, compounds in which iron is present in anionic form, such as in the above example, Al is soluble at higher alkalinities as aluminate. Cations may be taken in by exchange while anions require much respiration energy. Still, if the anion is mobile, not only plasmatical, out of the acid vacuole, the ferrite would automatically give off natrium of iron. It seems that no consideration of an element is complete without taking into account all of its possible modes of occurrence. The question requires further investigation.

[Baas Becking inserted Fig. 3.14, drawn after Correns (1939, Abbildung 45, p. 202).]

3.8.13 Silicon

27.74 % of the lithosphere, average 25.80 %. Oceans, in all rocks, except coastal water. Varieties of quartz, very common. In all natural waters, deposited as sinter from volcanic water. Solubility as given in Correns (1939, p. 129).103 See Figure 3.15. Al silicates found between pH 4-5 and >pH 11. Necessary for many organisms as functional element. “Carrier” element of soil.

3.8.14 Aluminium

7.85 % of the lithosphere, average 7.30 %, the most abundant of metals. With the exception of the fluoride, it always occurs in the oxidised state. In all rock, except sandstones, silicates, but also as Al2O3 corundum, as Al(OH)3 bauxite (tropical weathering of silicate rock) and AlF3 cryolite. Although not primarily necessary, it is present in the ash of most organisms, notably in higher plants (Lycopodiacea, Symplicos). Its solubility is very low at pH 5-9, after a fashion, this solubility is antagonistic to that of SiO2.104 At very low pH aluminium dissolves and yields very acid solutions (alum lakes).105

3.8.15 Magnesium

2.24 % of lithosphere 0.14 % hydrosphere, average 2.28 %. In pyroxenes, amphiboles and olivine, serpentinite H4Mg3Si2O9. From enstatite CaMg3Si4O12, talc is derived; H2Mg3Si4O12. Further, in sedimentary rock as dolomite CaMg(CO3)2 and magnesite MgCO3. Brucite is derived from talc and serpentinite, Mg(OH)2. The abundant metal is never found native. Very important in seawater, dolomitisation of organisms is secondary to lime formation. In green plants an integral part of the chlorophyll, also present in certain enzymes, as an ion it shows affinity to alkali metal ions.

3.8.16 Summary

[Baas Becking inserted Fig. 3.16 and Table 3.4.]

G. Harmsen (diss.), Aerobe cellulose aantasting [Aerobic cellulose affects] (in press).106

3.9.1 Introduction

[Baas Becking inserted Fig. 3.17.]

We shall start with the primary anabolite, glucose. This is, as a solid, at least a heterocyclic compound, the ring formed from 5 C atoms and one oxygen. The compound originates from perhaps six superimposed chlorophyll matrices, by transference of hydrogen from water to carbon dioxide. It may be that ascorbic acid is either an intermediary or that it plays a role as catalyser. 𝛽 Glucose is the central substance of biochemistry after J. Mark.107 It is the starting point for the formation of organic acids (Kluyver), of fats (Haehn and Kintoff, 1923 and 1924), of protein (Knoop, Oesterlin, Chibnall),108 and of the great number of other classes of substances. 𝛽 Glucose may be broken down by all, or nearly all organisms (see Section 7.1, The Concept of Symbiosis and Antagonism). It is rarely present in the outer milieu, as it is such a universal food.

3.9.2 Pectine substances, cellulose

Cellulose, pectine, chitine, lignine are present in the outer milieu. Cellulose is found from β glucose by dehydration, one water molecule disappearing between two sugar molecules. It forms long chains. Pectine is the methylester of pectic acid, chiefly galacturonic acid, together with cellulose and hemicellulose. Chitine is a chain glucose where, in every glucose molecule, one amino group is present instead of an OH. The molecule is moreover acetylated. Lignine is already aromatic shows the graphite lattice. It contains aldehydes and methoxy groups. All these polymeric substances have to be hydrolysed by means of enzymes before they may enter into metabolism. This seems to be particularly hard in the case of chitin, which is found, as such, even in certain Trilobites. Benecke (1905) described a Bacillus chitinovorus which is, however, only able to attack chitin if other organic food is offered as well.109 Other polymers may be named, sufficient to state that in the majority of cases they represent in the milieu. In summary: energy yielding food.

3.9.3 Formation of organic acids

[Baas Becking left this section blank.]

3.9.4 Summary and conclusions

In the section on metabiosis or succedaneous symbiosis (see Section 7.6, Heterosymbiosis, succedaneous (Metabiosis)).

3.10.1 Introduction

[Baas Becking left this section blank.]

3.10.2 Influence: physical milieu

[Baas Becking left this section blank.]

3.10.3 Influence: chemical milieu

[Baas Becking left this section blank.]

3.10.4 Summary and conclusions

[Baas Becking left this section blank.]

3.11.1 Introduction

[Baas Becking left this section blank.]

3.11.2 Minimum Law of Liebig

[Baas Becking inserted Fig. 3.18.]


3.11.3 Blackman’s optimal and limiting factors111

[Baas Becking left this section blank.]

3.11.4 Milieu factor (optima)

[Baas Becking left this section blank.]

3.11.5 Summary and conclusions

[Baas Becking left this section blank.]

3.12.1 Introduction

Rock decomposition is partly mechanical, partly chemical. Chemical decomposition is by water and carbon dioxide, yielding a solution of SiO2, alkali carbonates, alkali phosphates, lime, and siderite of which some oxidises to magnetite or haematite, pyroxenes and amphiboles go into solution most readily, then follow the plagioclase, feldspars, then orthoclase and mica, while muscovite is the most resistant of all (Clarke, 1916). The matrices may crumble and a “sieving” action of wind and water may set in, sorting the material as to size. As end products of the decomposition we get soils, with, as extremes, sand, laterite, kaolinite, bauxite. Table 3.5 taken from the classical work of Müller (1877), showing % of rock dissolved and % of undissolved mineral (seven weeks digestion in carbonated water).112

3.12.2 Origin of soils

[Baas Becking inserted Fig. 3.19, recalculated from Clarke (1916, p. 490).]

In clay we find only kaolinite Al2O32SiO2.2H2O, but also, and even more frequently, montmorillonite Al2O3 4SiO2.2 H2O, also containing Mg and Ca. Montmorillonite is able to swell. Halloysite is Al2O3 2SiO2.4H2O. These minerals are found in clay, they are found from feldspars, quartz, mica. Furthermore, we find the biogenic admixtures such as lime, silica and organic substances. Further, in the sediment there are found secondary minerals such as FeS, FeS2, glauconite. Due to the small pore volume of the clay (the air place has to be considered more fully), biological influences may be much greater here (anaerobiosis) than in sand. The weathered clay minerals are capable of base exchange; they may exchange NH4+ in the outer solution for another cation:

3.4 % K2O exchanged in montmorillonite! However, humus has even a higher exchange capacity!

3.12.3 Types of soil

Taking sand and silt as one, we may represent by a three component diagram the types of soil that interest us (Fig. 3.20). The components are

  • 1) sand/silt,

  • 2) lime and

  • 3) humus.

At the same time the diagram gives roughly the pH of these soils (id est the pH of the soil solution), an important fact, in as much as most plants are sensitive to pH and the optimum range for many agricultural plants have been carefully determined (Goedewaagen).113 From a pH of 3.5 in peat (see Section 2.4.8, Table 2.12) we range to a pH 9 in the pure lime. Good agricultural land contains the three components but still ranges in pH from 5.5-8. Studies “Kalkzustand”.

A humus percentage and a mechanical analysis might, therefore, in principle, characterise a soil. On acid soils we get inevitably, a leaching out of the mineral matter, especially of the metals. The soil podsolises,114 and usually the humus substance dissolved forms again a layer of hardpan, spoiling the physical structure. The ideal agricultural soil should have a high humus content and a pH a little below 6. It is represented by * in the diagram (chemogram; Fig. 3.20) (included here from table of Goedewaagen for pH and agricultural crops). Here below are given typical plant communities for the different types of soil (Russell).115 Humus is the cause of the CO2 production of soils (Hesselink van Suchtelen),116 alkali soils (black alkali) contain NaHCO3 and Na2 CO3.

In Figure 3.20, the laterite soils and the clay are not mentioned. Of course, the symbol SiO2 has to represent bauxite, montmorillonite, kaolinite, laterite and quartz. These minerals however, do not influence actual acidity as much as the humus, which is an active generator of H+ ions by exchange, as demonstrated in Section 6.3.4 of this book.

Humus. (Waksman, Naumann, Russell) Humus is a complex of plant and animal remains, partly mineralised, carbonised and caramelised, together with a living flora and fauna, consisting of bacteria, fungi, algae, protozoa, nematods, insects and crustacean, and their recretions, excretions and secretions and this complex is superimposed upon a mineral matrix. The organic and mineral matrix are both partly or fully saturated with capillary and colloidal waters. This complex, it stands to reason cannot be initiated by chemical or physical treatment of simple substances, as has often been attempted. From the data of geochemistry (Clarke, 1916) where several analyses of rock decomposition are given, it is known that with this decomposition the organic contents increase. It has often been assumed that the “metabolism” of the humus is so intense in tropical climates, that no accumulation occurs. Dr. Hardon, however found 5 % organic substance in a yellow Java lawn (oral communication).117 It is true that in the tropics leaf mould does not accumulate with the same intensity as in moderate climates, except where the pH is sufficiently low (the so called Borneo padango, for instance). Before the times of Justus von Liebig, it was assumed that plants needed this humus for their development. Liebig is the author of the mineral theory which, in a general form, still expresses the consensus of opinion. The virtue of stable manure or of “night soil” (China) was ascribed solely to the improvement of the soil structure and of the minerals contributed by the manure. A commercial fertiliser (guano excepted) used in enormous quantities, expresses the universal belief in the mineral theory. However, there are valid reasons to doubt the rigorous validity of this hypothesis in view of the fact, expressed at so many places in this essay, that plants are hardly ever dependent on other organisms. That nutrilites, or ergones, organic substances active in small or very small concentrations, might be as necessary for plant life as the mineral minimum elements! The manufacture of compost by biological means and with the use of a great many components might therefore yield an organic substrate immensely rich in ergones. Now it appears that excrements are particularly rich in ergones. The humus theory may be said to be revived. The mineral theory has been necessary to emphasise the fundamental facts of plant physiology. But the “ideal” plant, the organism totally independent of the organic environment, unfortunately rarely exists. “In principle”, plants are mineral feeders, synthesising their own organic matrix, but in practice they need more organic, than in organic minimum substances, the majority of which are, however, still unknown.

3.12.4 Properties of soil, particle size

For our purpose a rough classification into clay, silt and sand, suffices, and a characterisation in a simple triangle is all that is needed. Of course, the transitions between the three concepts are gradual, and therefore Figure 3.21, as used by Correns (1939), is to be preferred.

A clay, due to the fine nature of its particles, but also due to the open laminar structure of its components, will have little air space. Aeration is difficult, which is important for many plants. Tobacco roots require, for instance, a highly aerated soil (Van der Wey, 1932), while there are other plants (rice, willow, water lily) which may live in almost anaerobic conditions.118 Clay induces anaerobiosis. Sulphate reduction sets in lastly.

Correns (1939) has made use of a method which shows the composition of a certain soil quite clearly (Fig. 3.22). If one plots particle size on the abscissa, frequency (summated) on the ordinate, a soil which shows an even distribution of all fractions may be represented by a straight line. If there is a preponderance of a certain range of particle sizes, it will show as a “humus” in the curve. In this way, by integrating, we evade errors due to class size.

Soil in relation to water (see Russell and Russell, 1912),119 requires special treatment. Here the water holding capacity depends not only upon the size and shape of the interstice, but also upon the swelling of the soil colloids. It is important to note that montmorillonite is highly swellable. A soil may hold water still in dispersed condition (the soil particles being continuous) while mechanical shaking will cause the phase to revert (thixotrophy). This is particularly striking in sea sand (drifting sand).

3.12.5 Base exchange, zeolite action

The composition of the air in soil is variable. Roughly the CO2 contents goes in parallel with the humus percentage. In the original rock very curious gases occur, as Table 3.6, taken from Clarke (1916, p. 272), shows. [The composition of soil is summarised in Table 3.7.]

If the soil is well aerated, Azotobacter may function as a nitrogen fixing agent. In anaerobic soils Closteridium is active (see Section 6.4.2.a). Oxygen is, of course, variable. Hydrogen may be generated by cellulose fermentation and other fermentations. Hydrogen sulphide by sulphate reduction (or, as a secondary factor by “putrefaction of proteins”). It may be highly toxic to plants. Free ammonia only occurs in highly basic soils on the further composition of the soil solution. A soil without microbes, it should be stated, is a dead soil. The role of the organisms in the soil is still very imperfectly known. The contribution of ergones seems to be one of the chief acts (see Section 7.2, Ergones).

3.12.6 Summary and conclusions

[Baas Becking left this section blank.]

3.13.1 Introduction

[Baas Becking left this section blank.]

3.13.2 Rain

[Baas Becking inserted Table 3.8, taken from Clarke (1916).]

16 mg/L HNO3, 4 mg/L NH3 (Caracas, Venezuela), rain contributes up to 75 kg/Ha in salts. An analysis of rainwater from Wyster, Drenthe is given below. See Figure 3.23.

3.13.3 Freshwater

[Baas Becking inserted Fig. 3.24, a triangular plot of 15 waters of unusual composition].

See Figure 5.14 and Figure 6.3, Section 6.4.3.


3.13.4 Ocean water

See also Section 6.4.3, Changes in the hydrosphere and Section 5.7.6, Natural waters again.

[Baas Becking inserted Fig. 3.25, copied from Geobiologie, 1934; Fig. X.1 in Baas Becking, 2016.]

Nowhere on this planet one meets with conditions so stable as in the ocean, says L. Henderson.121

3.13.5 Brines

[Baas Becking inserted Fig. 3.26.]

3.13.6 Soil solution

[Baas Becking left this section blank.]

3.13.7 Dystrophic waters

[Baas Becking left this section blank.]

3.13.8 Physical factors, temperature, thermocline etc

[Baas Becking inserted Fig. 3.27.]

3.13.9 Summary and conclusions

[Baas Becking left this section blank.]


   B. Hubert was a PhD student of Baas Becking in Leiden. His experiments with Oospora were not retraced. Baas Becking (1935, p. 103-104), referred to studies in the Leiden Botanical Laboratory on the potential salt environment of the salt fungus Oospora halophila (Beyma) to the later fisheries biologist in the Dutch East Indies Dr J. Reuter. Reuter finished his PhD study in Leiden in 1936 with a thesis about the Malaria mosquito. Reuter (1936).
   In the introduction of Geobiologie (1934) Baas Becking referred to his example of ‘natural environment’. In the translation from 2016 (p. 5):
For example, the Opuntia (paddle cactus) and the rabbit were given perfect opportunities for expansion in Australia, as were muskrat in Europe and the wild oat in California.
   The example is based on Baas Becking’s own research in the Jacques Loeb Laboratory of Stanford University, the research of Jacoba Ruinen in Leiden and of Cornelis B. van Niel in the Jacques Loeb laboratory. In Geobiologie (1934) the organisms in the example are discussed on various pages. See Boone and Baas Becking (1931), Baas Becking (1931a), Baas Becking (1936b), Ruinen (1933), van Niel and Muller (1931) and van Niel (1932). See also Oren (2011).
   Baas Becking referred to the ubiquity of microbes that he discussed in Section 1.
   Milankovitch Cycles describe the collective effects of changes in the earth’s movements on its climate over thousands of years. The term is named for the Serbian geophysicist and astronomer Milanković (1879-1958).
   Reference to a light meter Amalux of Metrawatt A.G. in Nürnberg. Metrawatt is now part of GMC Instruments, together with Gossen and Camille Bauer.
   Baas Becking referred to the former inland sea Zuiderzee (or Zuyderzee), a shallow bay of the North Sea. in the northwest of the Netherlands, extending about 100 km inland and at most 50 km wide. In 1932 the majority of the Zuiderzee was closed off from the North Sea by the construction of the Afsluitdijk. The salt water inlet changed into a freshwater lake now called IJsselmeer (Lake IJssel) after the river that drains into it. In 1932 Baas Becking initiated the chemical research of the Ijsselmeer water that was done in the laboratory of the Rijksbureau voor Drinkwatervoorzienig by Dr. A. Massink (Baas Becking and Massink, 1934). Baas Becking presented the first results of the freshening of the Zuiderzee at the International Botanical Congress in Amsterdam in 1935 (Baas Becking, 1936).
   The first accurate measurements of the amount of ozone in the atmosphere were made by Charles Fabry and Henri Buisson at Marseilles in 1920: A Study of the Ultraviolet End of the Solar Spectrum. See also Dobson (1968).
   References to Luckiesch (1922) and to Hulburt (1928).
   Reference to Glaser and Coria (1935).
   Reference to Uyemura (1936). M. Uyemura working with samples from Japanese hot springs reported Amoeba verrucosa, Chilodonella sp., Lionotus, and Paramecium caudatum from temperatures between 36.0 °C and 40.0 °C; from the highest temperature range (30.0-50.0 °C) he recorded the hypotrichous ciliate Oxytricha fallax.
   Reference to William Henry Dallinger (1842-1909) and John James Drysdale (1817-1892) collaborated on a series of experiments on flagellate protozoa that demonstrated that their spores could survive at temperatures above boiling point, thus undermining evidence for the spontaneous generation of life in supposedly sterile liquids. The results were published in the Monthly Microscopical Journal (1873-1876).
   Reference to Efimoff (1924).
   Reference to Andrade (1934).
   Baas Becking referred to the work of Julius von Sachs (1832-1897), German botanist, from 1868 until his death Professor of Botany in the University of Würzburg. Among his extensive research in plant physiology, Sachs studied the influence of temperature on life processes (1860), especially the effects of freezing. He discovered the law of ‘cardinal points’, according to which each vital process has a minimum, an optimum, and a maximum temperature that are mutually related. In Geobiologie (1934) Baas Becking referred to his work in relation with the studies of van ’t Hoff and Svante Arrhenius in the section on Temperature, p 64-69. Baas Becking was probably referring to J. von Sach’s seminal monograph Experimental-Physiologie der Pflanzen [Experimental Physiology of Plants], published in 1865.
   Reference to Aristides Kanitz (1877-?), Romanian chemist, who published several studies on the effect of temperature on living organisms. Baas Becking referred to Kanitz (1915).
Jan Bělehrádek (1896-1980). Baas Becking referred to his Temperature and Living Matter (1935).
   Reference to Pierre Eugène Marcellin Berthelot (1827-1907), French chemist and politician, noted for the Thomsen-Berthelot principle of thermochemistry. He synthesised many organic compounds from inorganic substances.
   Reference to Crozier (1924).
   Reference to the law of mass action based on research performed from 1864 to 1879 by Cato M. Guldberg and Peter Waage. According to this law the rate of the chemical reaction is directly proportional to the product of the activities or concentrations of the reactants.
   In this section Baas Becking summarised different methods for determining the mechanical properties of the endoplasm.
In his 1953 manuscript Geobiology Baas Becking discussed Viscosity in Chapter IV, p. 227-230.
   Baas Becking summarised the method based on Einstein’s equation for Brownian movement, relating the translation of a particle undergoing Brownian movement to the viscosity of the suspending fluid. The problem however is that the viscosity of the cytoplasm is much higher due to the great concentration of granular material, because protoplasm is not a pure liquid or a true solution. Moreover, the protoplasma is not homogeneous. Baas Becking referred to his own research: Baas Becking, van de Sande Bakhuyzen and Hotelling (1928).
Harold Hotelling (1895-1973) was associate Professor of Mathematics at Stanford University from 1927 until 1931. He is known for Hotellings law, Hotelling’s lemma, and Hotelling’s rule in economics and well as Hotelling’s T-squared distribution in statistics.
Henriette Francisca Gerhards (1895-1966) was since 1925 the wife of H.L. van de Sande Bakhuysen who worked in the Stanford Food Research Institute. The research was part of her PhD study that she finished at Stanford in 1928. Baas Becking referred to Heilbrunn (1929) who wrote a critical review of “this interesting, but rather peculiar paper”. See also Heilbrunn (1956); Heilbrunn (1958). Baas Becking was not impressed by Heilbrunn’s critical remarks as is evident from a letter to F.A.F.C. Went from Pacific Grove December 9, 1929:
Some time ago, I was pleased to read an impossible critique of my viscosity study in Protoplasma by friend Heilbrunn, who is generally taken here as a querulant. I just didn’t answer it. I know Millikan agrees with me and that is better. Moreover, a young lady from Philadelphia, Dr Evelyn Miller, is coming here in January to work on this topic! It is a proof that Heilbrunn didn’t hurt me much.
Dr Evelyn Miller, not identified. See for H.L. Heilbrunn, Bereiter-Hahn, Anderson and Reif (1987).
Baas Becking also referred to J. Pekarek (University of Graz) who published in the 1930s several studies on viscosity measurements using the Brownian movement in Protoplasma.
   Baas Becking summarised here the centrifuge method, in which a cell is put in a centrifugal field. The particles in the endoplasm move either in a centrifugal or a centripetal direction due to the density difference between the particles and the cytoplasmic matrix surrounding them. The velocity of a particle (V) is given by Stokes’ law. Heilbrunn and his collaborators determined the viscosity of the endoplasm following the above principle.
Baas Becking further referred to the magnetic particle method where the movements of ferromagnetic particles in the magnetic field are influenced by the viscoelastic properties of the surrounding medium as well as the magnitude and gradient of the magnetic field and the magnetic susceptibility of the magnetic particles. Therefore, it is possible to determine viscoelasticity and yield stress of the protoplasm from the behaviour of a ferromagnetic particle in the protoplasm when a magnetic field is applied. Such an experiment was first carried out by Heilbrunn (1922), using slime mould plasmodia and then by Seifriz (1924).
   A reference to the Oswald viscosimeter: according to Baas Becking Geobiology 1953, p. 228:” much used by biologists”.
   The reference to “v. Leeuwen and Baas Becking” referred to Geobiologie (1934) Chapter IV, Figure IV.1. There the viscosity of various types of water is shown as a function of temperature. The measurement of natural brine from Sand Springs Nevada, Oswald viscometer, referred to ‘Oswald viscosimeter, van Leeuwen and B. Becking’. See also Section 3.5.5 Viscosity.
   Reference to Bělehrádek (1930, p. 30)
   See Baas Beckings reference to Edward Neveille da Costa Andrade (1887-1971) written in ink in Section 3.3, Temperature.
   Reference to Hille Ris-Lambers (1926).
   Reference to Bottelier (1935).
   According to Allen and Roslansky (1959):
Early estimates of “protoplasmic viscosity” were based on the unjustified and probably erroneous assumptions of homogeneity and Newtonian behaviour on the part of the cytoplasm. The use both of Stokes’s Law with the centrifuge method and of Brownian motion to estimate viscosity depend on the correctness of these underlying assumptions. The notion of cytoplasmic homogeneity should have been dispelled by the painstaking study of Brownian motion in Spirogyra cytoplasm by Baas Becking, Bakhuyzen and Hotelling, who showed that “Brownian” movements of cytoplasmic inclusions were often non-random (i.e. directed) and limited, indicating that the cytoplasm is heterogeneous and cannot be characterised by a single viscosity coefficient.
   Taco Hajo van den Honert (1899-1959), substitute director in Buitenzorg during WWII in the absence of Baas Becking; successor of Baas Becking as Professor of Botany in Leiden (1945a). Baas Becking referred to van den Honert’s Utrecht PhD thesis, Koolzuurassimilatie en Beperkende Factoren (1928), in which he published the results of his measurements of photosynthesis in Hormidium flaccidum.
   Reference to Von Kaleczinsky (1902) who suggested the use of stratified salt ponds as solar energy collectors. Baas Becking (1931a) referred to Von Kaleczinsky in his publication on Dunaliella viridis.
   Piezochemistry is the science dealing with the effect of pressure on chemical phenomena.
   Baas Becking referred to Emil Heinrich du Bois-Reymond (1818-1896), German physician and physiologist. Du Bois-Reymond’s law is a statement in physiology that a nerve is stimulated only by a change in electric current and not by a steady flow of electricity. Baas Becking applied the law in a broader perspective.
   Refers to Pfeffer (1884) who studied chemotaxis of mosses and ferns. See for more recent review Simons (1981) and Section 7.4.3.
   Refers to R. Stoppel (1915) who studied sleep movements of Phaseolus multiflorus and established a periodicity which she concluded was due to diurnal variation in atmospheric conductivity. She also showed that normal leaf movements are disturbed by completely insulating the plant from the earth and surrounding air.
   Refers to Antonia Kleinhoonte (1929) and Kleinhoonte (1932). See also Section 4.2.5, Kleinhoonte investigated the leaf movement of jack bean, Canavallia ensiformis.
   Refers to Blackman (1924) who conducted a meticulously controlled study of the growth of the coleoptile of individual barley seedlings treated with an electrical discharge. An increase in growth was observed.
   Reference to Muller (1928).
   Reference to Alexander Gavrilovich Gurwitsch (1874-1954), Russian and Soviet biologist, who contributed to the so called morphogenetic field theory in which ‘mitogenetic rays’ played a role. The theory is nowadays seen as ‘pathological science’. According to the field theory the orientation and division of cells was random at local level but was rendered coherent by an overall field which obeyed the regular inverse square law, an enterprise that required extensive statistical analysis.
   For a recent review of the effect of ultraviolet radiation on amphibians see Blaustein et al. (1998).
   Reference to Rahn (1916a). According to the abstract, the paper “presents a discussion of the principle of dynamogenesis, the generation of power, force, or energy, especially muscular or nervous energy.” In a following paper Rahn (1916b) the abstract reports: “The modern sensation as the psychical correlate of the process of stimulation of organs of sense might be traced from Plato, through Locke and Kant, to the fixing of the conception in the earlier experimental investigations of Weber and Fechner. The purpose of the present paper is briefly to trace this development, and then to point out some of the factors that are at the present time modifying or enriching our conception of the physical and physiological correlates of sensory consciousness.”
   Baas Becking referred to Rev. William Whewell (1794-1866), an english Professor of Mineralogy (1828) and from 1838 Professor of Moral Theology and Casuistical Divinity in Cambridge. His Astronomy and General Physics considered with Reference to Natural Theology (1833) was published as one of the eight Bridgewater Treatises as his contribution to the contemporary debate over the applicability of teleology to scientific questions. Henderson (1913, p. 3-8) was Baas Becking’s source for Whewell. Baas Becking regularly referred to Whewell in his unpublished manuscripts. On March 2, 1928 in his notebook with excerpts from his lecture course at Utrecht University, he quoted from Whewell’s Astronomy:
It has been shown in the preceding chapters that a great number of quantities and laws appear to have been selected in the construction of the universe; and that by the adjustment to each other of the magnitudes and laws thus selected, the constitution of the world is what we find it, and is fitted for the support of the vegetables and animals in a manner in which it could not have been, if the properties and quantities of the elements had been different from what they are.
Source: Handwritten manuscript AAS Basser Library Ms. 043 nr 159, p. 108.
   See for Bjerkness circulation theorem Chapter I.2.3.
   ‘Ellis’ not identified. Reference to Aschkinass (1895). Emil Aschkinass (1873-1909), Privatdozent Universität Berlin (1906-1909), who translated Ernest Rutherford’s Radioactivity in German in 1907. Aschkinass became a victim of the lethal effects of atomic radiation experiments in which he was involved, passing away in 1909 from overexposure to gamma rays.
   See for review Buiteveld, Hakvoort and M. Donze (1994).
   6 Baas Becking referred to Hulburt (1928).
   Reference to Woltereck (1913); Woltereck (1930), here Woltereck referred to Kikuchi (1928).
   In Geobiologie (1934) Chapter IV, Figure IV.1 of the viscosity of various types of water, shown as a function of temperature, there is a measurement of natural brine, saturates Sand Springs Nevada, Oswald viscometer with reference to van Leeuwen and B. Becking.
   Reference to Correns (1939, p. 119).
   Friedrich Johann Franz Czapek (1868-1921), Polish botanist developed a growth medium for propagating fungi and other organisms.
   Baas Becking referred to Keller (1925). The electrical factor in vital staining has been stressed particularly by Keller. He proposed to discontinue the division of dyes into acid and basic dyes, and to distinguish them according to their migration in the electric field, as cathodal or anodal dyes.
In the University of Arizona Library there is a master thesis By Harriet Mabelle Fogg (1930), The Physiological Activity of the Root as Indicated by Vital Staining, in which she acknowledges on the first page:
Dr. H.L. van de Sande Bakhuyzen for his suggestion of a problem which has proved to be very interesting.
H.L. van de Sande Bakhuysen (“Bakkie”) came to Stanford in 1925 as a colleague of Baas Becking. In 1928 he obtained a research place in the University of Arizona. He must have communicated with Baas Becking about his interest in vital staining and Keller’s study.
   Reference to the Dulong-Petit law, a thermodynamic law proposed by French physicists Pierre Louis Dulong and Alexis Thérèse Petit, states the classical expression for the molar heat capacity of certain chemical elements.
   On board of the M.S Annie Johnson near the Bay of Monterey, Baas Becking wrote to F.A.F.C. Went (June 19, 1928):
Here in Corinto I also had the great surprise of the trip! One morning when DrYates [from Deli] and I strolled along the beach (“Guppy’s whole book” is on the beach) we came to a strip about 500 metres long where the waves were coloured greenish brown. The beach was covered with a brownish mass! Immediately I thought of collecting my diatoms and a bit of sand in a matchbox, so I sunk on means to obtain a microscope […] To my great surprise, the diatom was again Aulacodiscus kittonii. […] Strange that this organism also occurs in masses in tropical seas! […] This find was worth the very long journey. [Translated from the Dutch AJPR]
Baas Becking collection, Library Boerhaave Museum Leiden. See for “Guppy” Section 4.3.7a.
   Reference to the ‘active osmotic water absorption’ theory by William Ringrose Gelston “Billie” Atkins (1884-1959), Irish chemist. He co-authored 10 papers with the plant physiologist Henry Horation Dixon (1869-1953) on osmotic pressure during his stay at the Botany group of Trinity College, Dublin (1906-1921). The root cells behave as an ideal osmotic pressure system through which water moves up from the soil solution to the root xylem.
See Atkins (1916), Dixon and Atkins (1915), Dixon and Atkins (1916).
   According to Rob Raiswell the reaction should probably be CaC2 + 2H2O = C2H2 + Ca(OH)2
Saponification is a process that involves conversion of fat or oil into soap and alcohol by the action of heat in the presence of aqueous alkali (e.g., NaOH). Soaps are salts of fatty acids whereas fatty acids are saturated monocarboxylic acids that have long carbon chains (at least 10) e.g., CH3(CH2)14COOH.
   Baas Becking referred to Harold Clayton Urey (1893-1981), American physical chemist, who was awarded the Nobel Prize in Chemistry in 1934 for “his discovery of heavy hydrogen” in 1932. In 1959 Baas Becking was irritated that Urey did not believe in the Franklin ammonia chemistry. See Section 2.5.2, Ammonia chemistry and note.
   Professor P. Cohen not identified.
   Baas Becking possibly referred to Rudolf Schoenheimer’s Harvey Lecture, January 21, 1937, The Investigation of Intermediary Metabolism with the aid of Heavy Hydrogen.
   Reference to Fowler and Bernal (1933).
   Refers to H.E. Armstrong (1908). Baas Becking discussed Amstrong’s view of water as a mixture of three polymers in Chapter V of Geobiologie (1934), section Water (p. 45, English edition, 2016).
   Baas Becking also discussed the theory of Barnes in Geobiologie (1934, p. 45-46).
References: Barnes (1932), Lloyd and Barnes (1932), Barnes and Jahn (1934 Barnes and Larsen (1935).
   Reference to Vouk (1929).
   Reference to Radermacher, Klas and Vouk (1940). By fervorisation the authors “understood the heating of plant nutrient-substrate to a high temperature”. See also Radermacher and Klas (1950). In the 1953 manuscript of Geobiology (p. 252) Baas Becking referred to the experiments:
It has been known for a long time that the heating of soil or of culture solutions may cause a remarkable increase in yield in plants grown in these solutions, as against controls. In the case of glucose containing solutions, the effect may be partly ascribed to the formation of dienoles, such as reductone. But Radermacher and Klas (1940) showed that if only the water were heated to 137 °C “(fervorised)” previous to the preparation of a mineral culture solution (von der Crone), increase of yield over the control could be demonstrated in various instances. As obvious sources of errors, like the shift in oxygen solubility with decreasing temperature, could be ruled out the effect seems to be a real one.
This work done in Zagreb, Yugoslavia, before the war caused much surprise. It was repeated at the Leyden Laboratory with positive results. The cause of this phenomenon is obscure. The effect may be enhanced when the mineral nutrient solution is fervorised as such.
Since the 1950s no reports on fervorisation were published. It seems that fervorisation belongs to the same class of phenomena as Lysenko’s ‘vernalisation’ see Section 5.2.3.
   See Baas Becking (1947b) for a description of the equilateral triangular plots. See also notes in Section 3.10, CH2 = CH2.
   Reference to Linus Pauling (1901-1994), American chemist, biochemist, chemical engineer, peace activist, winner of Nobel Prize (Chemistry, 1954; Peace, 1962), Pauling (1939). See also a reference to Pauling, Section 7.8.9, Figure and Table 6.2.
   Refers to Baas Becking, van de Sande Bakhuyzen and Hotelling (1928); Pekarek (1930). Pekarek refined his observations during the 1930s with several ‘Mitteilunge’ in Protoplasma. See for Henriëtte van de Sande Bakhuyzen-Gerhards also Section 3.3.6.
   See also Section 4.4.4 where Baas Becking referred to the unidentified author ‘Beyer’.
   Present name Helaeomyia petrolei (Coquillett, 1899). Baas Becking referred to Thorpe (1930). In the 1953 manuscript of Geobiology (p. 244-245), Baas Becking referred to Thorpe:
Organisms living under conditions of drought, whether exposed to the atmosphere, or in non-aqueous solutions, have to subsist on metabolic water. The best known cases are the flour moth and the clothes moth, although the occurrence of the curious fly Psilopa petrolei described by Thorpe (1930) from oil wells, (the larvae of which feed on “oil” microbes) suggest that either the larvae of the microbes should make use of metabolic water. Here is another field for the use of isotopes.
See also Section 4.4.4 where the author of the clothes and wax moth is mentioned as Beyer (not identified).
   Heinrich Otto Wieland (1877-1957), German chemist who won the Nobel Prize in Chemistry in 1927. Baas Becking referred to Wieland’s research on the oxidation of acetic acid by yeast cells.
   The reference is to Thomas Graham (1805-1869), Scottish chemist, pioneer in dialysis and diffusion of gasses, founder of colloidal chemistry. According to Graham the special nature of colloids can be traced back to ENERGIA, the source of force in vital phenomena. Colloids are presented as the likely source of biological activity and hence the vital source of life.
See Graham (1861) and Ede (2007).
   Baas Becking probably gave his lecture to the California Academy of Sciences in San Francisco. The text of the lecture was not retraced.
   In the 1953 version of Geobiology (p. 250-251) Baas Becking gave an historical overview of the development of the osmotic theory, with references to the work of Dutch 19th century scientists as Hugo de Vries, van’t Hoff and van der Waals. He further referred to his work in the Unilever Laboratory in 1943:
The problem of the state of water in colloidal systems was approached from another angle. Gortner approached the problem from a colloid chemical angle, that more advance was made. According to Gortner, water may exist, in a colloid (like protoplasm) in various states: it may exist as free molecules, as molecules bound osmotically or as hydrates and further it may occur as swelling water, tightly bound to hydrophilic, colloidal particles.
Very soon this idea was applied to the problem of hardiness, both against drought and against frost and a number of workers, have attacked the problem from many angles. “Bound” water does not freeze, it remains in the liquid state at low temperatures. The author (1943 unpublished) could demonstrate anylase activity in deep frozen fruit at -25°C, while fish livers became rancid at this temperature within a few months. There is good evidence to assume that part of the water in a tissue remains unfrozen at low temperatures.
Determinations have been made of the freezing point itself, the expansion at the freezing point and of the latent heat of fusion of ice. The last method seems at least objectionable. It was found that, in general, hardiness increases in plants with an increase of non-freezable water. It should be stated, however, that the road here is beset with pitfalls and that no consensus of opinion exists as to the colloidal “status” of bound water.
Experiments, comparing hardened and unhardened races have to take into account the, often large, differences in water content of these races, the lowering of their freezing point due to osmotically active substances and the water bound as hydrates (e.g., in the carbohydrates).
According to his unpublished bibliography 1948 he wrote the following reports for N.V. Unilever (restricted 1941-1944 and unpublished).
  • (a) The cytology of the strawberry, with a key to sixty commercial varieties.

  • (b) The anatomy of the asparagus.

  • (c) Browning in fruits and the use of dienoles.

  • (d) Super quick freezing and cell size.

  • (e) Free and bound water in deep freezing and enzymatic activity.

  • (f) Methodology of vitamin C determination.

  • (g) Organoleptic research and the measurement of primary tastes and of odours.

Typescript AAS Basser Library Ms. 043 nr. 161.
   Reference to Gortner (1930), Gortner (1932). See also Section 5.4.2.
   Reference to Newton and Martin (1930), Scarth and Levitt (1937).
   Baas Becking copied the formula, figure and table in this section from Geobiologie (1934). See also Section 3.7.2.
   Pasteur described in 1862 an organism consisting of small spherical cells joined together in chains that were capable of decomposing urea, it was named Torula ureae.
The organism was subsequently named Micrococcus ureae. In 1891 Miguel described seven species of Bacillus, nine Micrococci and one Sarcina with the power of decomposing urea.
   The values of the dissociation constants were taken from the average values in Sun, Nesic and Young (2008).
   Reference to van Niel (1932) and Pop (1936). In her PhD Thesis Leiden (Baas Becking, supervisor), T. Pop showed that green algae and flagellates are often resistant to H2S.
   Baas Becking referred to section Sulfidische Sedimentare Lagerstatten in Correns (1939, p. 209-210).
   The source to which Baas Becking wished to refer was not identified, however, for a review of the knowledge on solubility of SO2 at the end 1930s see Beutschlein and Simensson (1940).
   See also Section 6.4.2.c, Pollution.
   Reference to Carl Adolph Hugo von Wolzogen Kühr, a microbiologist from the Delft school. The classical theory of anaerobic bacterial corrosion, postulated by Von Wolzogen Kühr and van der Vlugt, states that certain organisms, primarily those of the bacterial genus Desulfovibrio, remove hydrogen (electrons) that accumulate on the surface of iron (cathodic depolarisation) by means of a hydrogenase, and reduce SO42 to S2-. As a result of electron removal, iron dissolves as Fe2+ ions at the anode. Baas Becking probably referred to Von Wolzogen Kuhr and van der Vlugt (1934).
   Hydrogenomonas species are able to grow autotrophically by means of their ability to oxidise hydrogen gas for energy and to reduce carbon dioxide to cell material. The oxidation of hydrogen is accomplished by the hydrogenase system which catalyses the reaction H2 → 2H+ + 2e. Providing that electron transport occurs via the cytochrome system with the reduction to water, 3 moles of ATP would be expected per mole hydrogen oxidised. See Sokatch (2014, p. 194).
   Reference to the work of Lieske (1929) in German coal mines. See Fischer, Lieske and Winzer (1932, p. 2).
   Baas Becking probably referred to papers of Langdon and Gailey, who showed that there was present an average of 4 percent (by volume) of carbon monoxide in the pneumatocyst of the giant Pacific Coast kelp, Nereocystis Luetkeana. See Langdon (1917), Langdon and Gailey (1920).
“Hoagland” refers to Dennis Robert Hoagland (1884-1945) Professor of Plant Nutrition at University of California at Berkeley (1927-1949).
   Otto Heinrich Warburg (1883-1970), German biochemist, awarded Nobel Prize for Physiology and Medicine in 1931 for his research on respiration. By 1932 Warburg had isolated the first of the so called yellow enzymes, or flavoproteins, which participate in dehydrogenation reactions in cells, and he discovered that these enzymes act in conjunction with a non-protein component (now called a coenzyme), flavin adenine dinucleotide. In 1935 he discovered that nicotinamide forms part of another coenzyme, now called nicotinamide adenine dinucleotide, which is also involved in biological dehydrogenations.
   Baas Becking referred to the work of Wattenberg (1938) on the CaCO3 saturation of seawater in the Atlantic Ocean, referred to in Table 40 (p. 192) in Correns (1939). See also Section 3.6.8.
   Reference to Molisch (1911) and Molisch (1937). Hans Molisch published already in 1884 about the effect of gases on plants: Molisch (1884). In 1937 Molisch published, Der Einfluss einer Pflanze auf die andere Allelopathie.
It is remarkable that Baas Becking did not refer to the Utrecht PhD Thesis of Pieter Adriaan van der Laan (1934), Der Einfluss von Aethylen auf die Wuchsstoffbildung bei Avena und Vicia.
See for review Michael Evenari (1961) Chemical influences of other plants (allelopathy).
   Reference to Denny (1924, 1927). In 1923, Denny secured a patent covering the use of ethylene for the forced colouration of fruit. (U.S. Patent No. 1,475,938). See also Wray-French (2013).
   Nicolai and Baas Becking (1935). Marie Françoise Emilie Nicolai (1900-1961) was assistant of Baas Becking in the Leyden Botanical Laboratory.
   Reference to Gouwentak (1941). Cornelia Adriana Gouwentak (1902-1977), plant physiologist in Wageningen, married her teacher professor Dr. E. Reinders. January 2, 1960, a Bulgarian student Josif Lulev fired three shots with a pistol on her because she refused to let him pass his examination. She survived the assault with a bullet in her shoulder. Lulev was sentenced to 11 months in prison. When he was released, he left for Freiburg, Germany, where in 1964 he does what Cornelia Reinders-Gouwentak considers impossible. He graduates in forestry and gets his PhD there five years later.
   Baas Becking probably intended to include the table, from the Critical Tables I of Humphreys (1926, p. 393). In the 1953 version of Geobiology (p. 88) he included the table. Baas Becking wrote in Geobiology (1953, p. 85-86):
Water vapour forms another very important part of the lower atmosphere. The atmosphere’s water vapour content decreases at first with increasing altitude; but at very great heights it increases again. That water vapour does not follow gravity laws as the other gases is due to its high boiling and melting points. At the low temperatures at higher altitudes water condenses (on dust particles as nuclei) and forms liquid water drops and even ice crystals, forming clouds which though heavier than air are born by air currents.
   Frans Herman Hesselink van Suchtelen (1884-1937), published research in soil chemistry. He died as a result of an accident at Apeldoorn on June 23, 1937, at the age of fifty three years. Van Suchtelen was for some years connected with the New Jersey Agricultural Experiment Station, the Michigan State College and the Massachusetts Agricultural College. See Science 23, 86, 2221, p. 73, July 1937. Baas Becking probably referred to Hesselink van Suchtelen (1931).
   Baas Becking (1947b) published his method for graphical representation of the properties of three chemical components by means of an equilateral triangle in 1947 in an article signed ‘Leiden Buitenzorg 1945-1946’. The figure in the manuscript is Figure 1 in the 1947 publication. In 1947 Baas Becking did not refer to Hesselink van Suchtelen. The presentation of results by means of an equilateral triangle was described in Geobiologie (1934), with reference of unpublished results by himself and Dr. A. Massink. In 1934 Baas Becking and Massink published their recently developed method of description of natural waters in On the Changes in the Composition of Natural Waters (Baas Becking and Massink, 1934).
In the introduction of the manuscript of Geobiology (1953) Baas Becking described the triangular representation of data again (p. 9-10):
G.G. Stokes, in 1891, proposed a graphical representation of the properties of three components by means of an equilateral triangle, and this method has been used ever since, chiefly in phase rule work and in soil science. The representation is based upon the well known property of an equilateral triangle; the sum of the distances of any point within this triangle to the sides is constant. A complex of three variables may be represented by this method showing a considerable advantage of the, more usual, plane representation of a space model. It widens our scope in many respects and allows of a welcome extension of the visual methods, so dear to the biologist (Baas Becking, 1947b).
   Possibly reference to the Finnish entomologist, Professor Enzio Reuter (1867-1951), Helsingfors.
   Baas Becking copied the formulas of Michaelis from Chapter V of Geobiologie (1934) on one of the first pages of the manuscript of Geobiology (1944), left of the first page of the table of contents.
   Reference to ‘Johnston’ unknown. Possibly James Johnstone (1870-1932), Scottish biologist and oceanographer.
   Reference to Leonor Michaelis (1875-1949), German biochemist, known for his work on enzyme inhibition, pH and quinonens as well as for his work with Maud Leonora Menten (1879-1960) on enzyme kinetics published in 1913. Baas Becking referred to Michaelis (1914). The calculation was taken from Geobiologie (1934, p. 40-43 English edition, 2016).
   Baas Becking referred to Wattenberg and Timmerman (1936).
   Baas Becking and Nicolai (1934); Thompson et al. (1927).
   Reference not identified.
   Reference to Cooper (1935), Cooper (1937). For L.H.N. Cooper see also Section 6.1.2 under Iron. According to Cooper (1935) it seemed possible that in seawater with solutions containing more than 100 mg fluoride ion per litre, ferrifluoride might prove more difficult to reduce than ferric iron.
   The reference is to Correns (1939, Abb. 3 p. 129).
   According to Britez et al. (2002):
the formation of an Al-Si complex in the shoot tissues of F. marginata, may substantially contribute to the internal detoxification of Al.
See also Taylor, Jugdaohsingh and Powell (1997).
   According to Baas Becking the acidity in Alum lakes in Western Australia is due to hydrolysis of salts of heavy metal. See Baas Becking (1938a), On the Cause of the High Acidity in Natural Waters, Especially in Brines.
   Reference to Onderzoekingen over de Aerobe Celluloseontleding in den Grond (1946, Groningen PhD thesis of Georg Wilhelm Harmsen (1903-1981), soil microbiologist who worked in the 1930s in the reclaimed polder Wieringermeer on pyrite oxidation and decomposition of cellulose in soil. Although he completed his thesis in 1939, the public defence had to be postponed until 1946. See Mulder (1982).
   Baas Becking referred to Herman Franz Mark (1895-1992), Austrian-American chemist. He received on July 5, 1944 in the Utrecht prison from C.J. Niekerk-Blom a copy of Mark’s The General Chemistry of High Polymeric Substances (Mark, 1940). See also Section 5.1.3.
   Reference to Knoop and Oesterlin (1925). Also reference to Chibnall (1939).
   For Benecke (1905) see also Section 6.4.4.e.
   110 In the 1953 version of Geobiology Baas Becking gave a detailed section on The Influence of the Environment on Vital Processes (p. 410-428). He summarised the work of Liebig, Blackman en Mitscherlich as follows:
The organism is subject to a multiplicity of external factors and the integration of these factors, at a given moment determines, in many cases, the intensity of a vital function, such as growth, photosynthesis or respiration. At first sight it would seem a hopeless task to analyse a process subject to so many variable influences. Certain theoretical considerations have been developed which seemed to bring order in this chaos. At present, however, we are less confident in the discovery of the general applicability of the theory, first formulated by Justus van Liebig in 1853 as the “Law of the Minimum”. This great chemist, in studying the relation between yield of an agricultural plant and nutrient mineral (N1) added showed that the yield curve (yield as a function of added nutrient) is a straight line, which shows at a certain value of nutrient added, a sharp discontinuity, after which it becomes parallel to the abscissa. Beyond a certain concentration, the nutrient is no longer effective. According to Liebig, another nutrient has become the “minimum factor” and addition of this new nutrient (N2) will again increase the yield until it is no longer effective.
Similarly, we may conceive of a kinetic analogue, articles prepared by subsequent manipulations on an endless belt. Here the slowest manipulation determines the yield. De Vries (1939) cites cases in which “Liebigian” yield curves have actually been obtained in agricultural experimentation (chiefly in pot experiments). Blackman, as a result of his experiments on leaves (Blackman, 1905) reached a similar conclusion for the factors influencing photosynthesis; temperature, light intensity and carbon dioxide tension.
It was soon found that the “minimum” factor, in yield studies, is of greater influence if the other “production factors” are optimal. This means that the “pitch” of the curve will vary according to the nutritional condition of the plant and that also the maximal yield should be attained at a different rate. Mitscherlich (1931), while granting that a certain production factor is influenced by the level of the other production factors, claimed that the production factor studied will (independent of the others) always cause a fixed percentage of the maximum yield. This would mean that, let us say, the points indicating a given yield will have the same abscissa.
Eilhard Alfred Mitscherlich (1874-1956), German agriculturist. Mitscherlich’s most important scientific achievement the law of effect of growth factors. In contrast to the law of the minimum established by Justus von Liebig, according to which, of all mineral nutrients, those that are present in the smallest amount in the soil determine the plant yield decisively, Mitscherlich demonstrated that the yield level depends on all growth factors. According to his research results, each individual growth factor can increase the level of income with a specific intensity (effect factor). However, as you approach the maximum yield, the additional yield becomes significantly lower due to a further increase in a certain growth factor compared to the expenditure.
   Reference to Blackman (1905).
   Clarke (1916) took Table 3.5 from R. Müller (1877, Table p. 39). According to Clarke (1916), “Müller gives a good summary of previous work upon the subject.”
   Matthijs Arnoldus Jan Goedewaagen, PhD Utrecht 1933, De Invloed van de Nitraatconcentratie der Voedingsoplossing op den Groei van Tarweplanten, supervisor F.A.F.C. Went. Baas Becking referred to Goedewaagen (1941).
   Podsolisation is a complex soil formation process by which dissolved organic matter and ions of iron and aluminum, released through weathering of various minerals, form organo-mineral complexes (chelates) and are moved from the upper parts of the soil profile and deposit in the deeper parts of soil.
   Reference Russell and Russell (1912), Soil Conditions and Plant Growth. See also Section 1.2.3.b.
   Hesselink van Suchtelen (1923), Energetik und Mikrobiologie des Bodens.
   Reference to Dr. H.J. Hardon, agricultural experimental station Buitenzorg Java, he published about the mineralogy of clay in Java in the 1930s.
   Reference to Hotze Gysbert van der Wey, who defended his PhD thesis Der Mechanismus des Wuchsstofftransportes, in 1932 in Utrecht. Supervisor F.A.F.C. Went. In the 1930 and 1940s van der Wey did research on the mosaic problem in tobacco cultures and the relationship between soil type and mosaic, in Medan, Sumatra, at the Deli tobacco culture station.
   Russell and Russell (1912), Soil Conditions and Plant Growth.
   Reference to the Danish physicist Martin Hans Christian Knudsen (1871-1949). Knudsen was also active in physical oceanography, developing methods of defining properties of seawater.
Baas Becking gave the relation between Salinity (S) and Chlorinity (Cl) that Knudsen published in 1901 as S = 0.03 + 1.805 Cl. In the 1953 version of Geobiology (Baas Becking, 1953a), he referred to the Knudsen relation (p. 322):
An empirical relation between the total solids and chlorinity was derived by Knudsen: S % = 0.030 + 1.8050 Cl %. This relation, however, only applies to seawater diluted with rain or feebly concentrated by solar heat. Deviations from Knudsen’s equation occur when river water is mixed with seawater.
See Lyman (1969), Knudsen (1901). I thank Dr.Ir. Laurène Bouaziz (Delft) for the reference to Lyman and Knudsen.
In his lecture during the Sixth International Botanical Congress in Amsterdam in September 1935, Baas Becking (1936a) remarked that the Knudsen relation “cannot be applied to the brackish waters of the [freshening] Zuyderzee”:
If North Sea water is diluted with distilled water (comparable to the extremely pure Swedish and Russian rivers, which empty into the Baltic), Knudsen’s equation does not apply, but the rather high amount of dissolved salts in the Netherland’s river water, such as Yssel water, exert a marked influence upon the composition of the mixture.
Baas Becking referred to the Dutch research on the chemical and biological processes of freshening of the water of the former brackish inland Zuiderzee since the closure of the 32 km long Afsluitdam in 1929.
Not only a process of dilution, a considerable shift in the ionic proportions may occur and, consequently, the antagonistic action of ions is greatly changed. My own experiments upon euryhalinic organisms have convinced me that the shift in ionic proportions is as important as the decrease in osmotic pressure – the differences in the plankton of the Baltic and the former Zuiderzee may be, at least partially, accounted for by this fact.
   Baas Becking referred to Chapter V in Henderson (1913):
Certainly, nowhere else where life is possible, probably in no other place in the universe except another ocean, are so many conditions so stable and so enduring (p. 186, edition 1970).