17<) SESSION II. DISCUSSION 



are the essential components of the protoplasm of the cells of animal and vegetable 

 organisms, are dissymmetrical in structure. It would therefore be natural to suppose that 

 this 'microdissymmctry' of the molecules would also manifest itself, to some extent, in 

 the shape of the body. Such a conclusion would, however, be too hasty, we have no 

 experimental proof that such is the case. Such a mechanistic concept of the relationship 

 between the dissymmetry of the molecules which compose the protoplasm and dissym- 

 metry of the external form of the body or its separate organs will always lead to failure, 

 as, for example, the attempt [5] to establish a dificrence in the effect of powdered L- or 

 D-quartz on the right and left lungs of animals, although these did not show spiral dis- 

 symmetry. 



Let us first consider the phenomenon of dissymmetry in inorganic nature which must 

 have preceded the organic world. The inorganic world differs fundamentally from the 

 organic in that one optical isomer does not predominate in it; as G. G. Lemmlein [6] has 

 shown in the case of quartz, optically active crystals always form closely associated twins 

 or both enantiomorphs are found together in equal amounts in the mineral formation 

 where they occur. Nevertheless, the dissymmetry of such minerals probably played some 

 part in the development of organic living material on the Earth [7, 8]. It is known that 

 optically active crystals of quartz may serve as a dissymmetric factor in catalytic reactions 

 which take place under conditions similar to those under which natural syntheses occur, 

 and this is experimental proof that the dissymmetric lattices of crystals could play a part 

 in the creation of living material [9]. In nature, however, such reactions occurring on the 

 surfaces of crystals could not lead to a preponderance of one optical isomer because the 

 amounts of D- and L-crystals are equal in the inorganic world. We must therefore look 

 for some other cause for the occurrence of dissymmetric organic substances. Photo- 

 synthesis might constitute such a factor. 



The possibiUty of producing such an effect when an asymmetric reaction occurs under 

 the photosynthetic influence of circularly polarized light, even when the preponderance 

 of one sign is only very small, has been confirmed by the well-known experiments of 

 Kuhn, Tenney et al. [10]. Their results are convincing testimony of the selective action 

 of circularly polarized light on the vital activities of living material. The predominance of 

 one structural isomer of amino acids in the proteins of protoplasm is, therefore, not a 

 chance occurrence. It is explained by the action of the right circularly polarized com- 

 ponent of scattered sunlight throughout the long years of the evolution of the living 

 world. This component has been shown to exist by many experiments [11]. The amount 

 of circularly polarized light in relation to the total radiation is greater at higher latitudes 

 than close to the equator. In view of this one would expect a corresponding picture of 

 the geographic distribution on the Earth of animals having a dissymmetric form of body; 

 in the equatorial zone there should be an equal prevalence of right and left forms, while 

 in higher latitudes one form should predominate. Not only latitude, but height above 

 sea level also sometimes determines the prevalence of one or other spiral form of the 

 body and this must surely be related to the amount of polarized light falling on the parti- 

 cular portion of the surface of the Earth. As concerns the vegetable kingdom, here the 

 arrangement of the leaves is characteristically spiral or alternate but the preponderance 

 of one form in association with geographical distribution has never been observed any- 

 where [12]. The plant world would appear to be a kind of bridge between tlie molecular- 

 racemic world of inorganic nature and the animal kingdom with its clearly expressed 

 dissymmetry of the macromolecules of proteins of protoplasm. It would appear that the 

 relatively small proportion of optically active constituents in comparison with tlie total 

 mass of racemic compounds is not enough for it to be manifested as morphological dis- 

 symmetry of the body. It is, however, manifest in the configuration of the elements of 

 the detailed structure of plants: according to the observations of Alpatov [13] the thicken- 

 ings in the walls of the conducting vessels are always in the form of a left-handed spiral, 

 regardless of the arrangement of the leaves of the plant. 



There is another type of living organism, the soil bacterium Bacillus mycoides, which 

 has a colony reminding one of a spiral nebula, the direction of growth being counter- 

 clockwise (left-handed form). Investigations by Nastyukova [14] have shown that all 

 soils in the U.S.S.R. arc inhabited by this left-handed form alone, with the exception of 

 the Transcaucasus, Central Asia and the Ussuriï region where the right-handed form 

 predominates. This form also predominates in some of tlie mountainous regions of South 

 America while the left-handed form is widely distributed on the plains. A similar speci- 

 ficity of geographical distribution is also seen among widely distributed marine molluscs, 



