448 



NA TURE 



[September 30, 1922 



The Progression of Life in the Sea. 1 



By E. J. Allen, D.Sc, F.R.S. 



DIFFERENT views are .still held as to where life 

 in the world had its origin, but no one questions 

 that it began in close connexion with water. That it 

 1 in the sea, where the necessary elements were 

 present in appropriate concentrations and in an ionised 

 state, is an idea which appeals to many with increasing 

 force the more closely it is examined. This view has 

 been developed recently by Church 2 in his memoir 

 on " The Building of an Autotrophic Flagellate," in 

 which he. boldly attempts to trace the progression from 

 the inorganic elements present in sea-water to the 

 unicellular flagellate in the plankton phase, floating 

 freely in the water. ,The autotrophic flagellate, manu- 

 facturing its own food, he regards as the starting-point 

 from which all other organisms, both plants and 

 animals, have sprung. To understand the first step 

 in this progression, the passage from the dead inorganic 

 to the living organic remains, is as it has always been, 

 one of the great goals of science, not of biological science 

 alone, but of all science. Recent research has, I think, 

 thrown much light on the fundamental problems in- 

 volved. In a paper published last year, Baly, Heilbron, 

 and Barker. 3 extending and correcting previous work 

 by Benjamin Moore and Webster, 4 have shown that 

 light of very short wave-length (A = 200 /z/i), obtained 

 from a mercury-vapour lamp, acting upon water and 

 carbon dioxide alone, is capable of producing formalde- 

 hyde, with liberation of free oxygen. Light of a some- 

 what longer wave-length (A = 290 fi/j.) causes the mole- 

 cules of formaldehyde to unite or polymerise to form 

 simple sugars, six molecules of formaldehyde, for 

 example, uniting to form hexose. The arresting fact 

 brought out in these researches is that the reactions 

 take place, under the influence of light of appropriate 

 wave-lengths, without the help of any catalyst, either 

 organic or inorganic. Where a source of light is used 

 which furnishes rays of many wave-lengths, the simple 

 reaction of the formation of formaldehyde is masked 

 by the immediate condensation of the formaldehyde 

 to sugar, but this can be prevented by adding to the 

 solution a substance which absorbs the longer wave- 

 lengths, so that only the short ones which produce 

 formaldehyde are able to act. 



When the formation of sugars is postulated, the 

 introduction of nitrogen into the organic molecule 

 offers little theoretical difficulty ; for not only has 

 Moore 5 shown that nitrates are converted into the more 

 chemically active nitrites under the influence of light 

 of short wave-length, but he maintains that marine 

 algae, as well as other green plants, can, under the same 

 influence, assimilate free nitrogen from the air. Baly 6 

 also has succeeded in bringing about the union of 

 nitrites with active formaldehyde in ordinary test- 

 in I >es by subjecting the mixture to the light of a 

 quartz-mercury lamp. 



1 From the presidential address delivered to Section D (Zoology) of the 



I'.i iti !i \ ia in at 1 lull on Sept. 8. 



- "Biological Memoirs*'-' I. Oxford, 1919. 



Chem. Soc, London, vols. 119 and 120, 1921, p. ioj> NATURE, 

 p. 344. 

 Nov. Soc. B., vol. 87, p. 163 (1913), p. 556 (1914) ; vol. 90, p. 168 



• 

 Roy, Soc. B., vol. 90, p. 158 (1918) ; vol. 92, p. 51 (1921). 

 Heilbron and Hudson, Journ. Chem. Soe., London, vols. 121 

 .o-l [22, 1922, p. 1078, 



If these results of the pure chemist are justified, they 

 go far towards bridging the gap which has separated 

 the inorganic from the organic, and make it not too 

 presumptuous to hazard the old guess that even to-day 

 it is possible that organic matter may be produced in 

 the sea and other natural waters without the inter- 

 vention of living organisms. We may note here, too, 

 that if we take account of only the most accurate 

 and adequately careful work, the actual experimental 

 evidence at the present time requires the presence of 

 a certain amount of organic matter in the culture 

 medium or environment before the healthy growth of 

 even the simplest vegetable organism can take place. 



Let us then assume that we are allowed to postulate 

 in primitive sea-water or other natural water organic 

 compounds formed by the energy of light vibrations 

 from ions present in the water, and see how we may 

 proceed to picture the building up of elementary 

 organisms. Without doubt the evolutionary step is 

 a long and elaborate one, for even the simplest living 

 organism is already highly complex both in structure 

 and function. As the molecules grew more complex 

 by the progressive linkage of the carbon atoms of newly 

 formed carbohydrate and nitrogenous groups, we must 

 suppose that the organic substance, for purely physical 

 reasons, assumed the colloidal state, and at the same 

 time its surface-tension became somewhat different 

 from that of the surrounding water. With the assump- 

 tion of the colloidal state, the electric charges on the 

 colloidal particles would produce the effect of adsorption 

 and fresh ions would be attracted from the surrounding 

 medium, producing a kind of growth entirely physical 

 in character. We thus arrive at the conception of a 

 mass of colloidal plasma differing in surface-tension 

 from the water and increasing in size by two processes, 

 one chemical, due to linkage of carbon atoms ; the 

 other physical, brought about by the adsorption of 

 ions by the colloidal particles. 



The difference of surface-tension would tend to make 

 the surface a minimum and the shape of the mass 

 spherical. On the other hand, maximum growth would 

 demand maximum exchange with the surrounding 

 medium, and hence maximum surface. From the 

 antagonism of these two factors, surface-tension and 

 growth, there would follow, first, the breaking up of 

 the mass into minute particles upon the slightest 

 agitation, and, secondly, changes of form wherever 

 growth involved local alterations of surface-tension ; 

 the latter would represent the first indication of the 

 property of contractility. 



So far we have considered only the process of the 

 building up of the elementary plasmic particles, the 

 anabolic process. Church, whose memoir already 

 referred to I am now closely following, points out that 

 these anabolic operations must from the beginning 

 have been subject to the alternations of day and night, 

 for during the night the supply of external energy is 

 removed. " If during the night," he asks, " the 

 machine runs down, to what extent may it be possible 

 so to delay the onset of molecular finality that some 

 reaction may continue, at a lower rate, until the 

 succeeding day ? " And his answer is : " The suc- 



N( 1. 2761, VOL. I io] 



