178 SESSION II. DISCUSSION 



Almost all the original types ol the more viable organisms were formed during the 

 Tertiary and superseded the earlier forms which could only persist in areas where the 

 intensity of the radiation remained relatively high enough. We must thus consider the 

 reason for the emergence of new forms of organism as being changes in the intensity 

 and nature of solar radiation. 



The facts we have been discussing give an indirect indication of a possible connection 

 between the dissymmetry of molecules and that of the body-form of many organisms, 

 the existence of which was postulated by V. I. Vernadskii. \X'e have no direct evidence 

 for this at present. Thus, Polarimetrie analysis of amino acids obtained by hydrolysis of 

 the conchiolin from the shells of right-handed and left-handed molluscs (Fruticicola 

 lantzi Lindh., Aplexa hypnorum and Limnaea stagnalis) have not, so far, given any indica- 

 tion of a connection between dissymmetry of body-form and the optical isomerism of the 

 amino acids of which the protein is composed [i8]. A negative result was also obtained 

 in a study of the amino acids of the proteins of the tissues of the foot of left-handed and 

 right-handed specimens of the mollusc Fruticicola lantzi Lindh. It is true that neither 

 of these results can be considered to be conclusive in that the solutions studied were 

 not very transparent and could, only with difficulty, be studied polarimetrically. It would 

 be very desirable to repeat these investigations using modern methods. 



It may be assumed that the formation of organisms having a dissymmetrical body-form 

 is determined by the action of dissymmetric factors on specially sensitive receiving 

 centres — optically active receptors in the protoplasm which, it would seem, are also 

 sensitive to circularly polarized light [19, 20]. This is shown by the studies of Alpatov [21] 

 and others which established that there is, in fact, a receptor in the bodies of right-handed 

 and left-handed organisms on which optically active poisons act selectively. Furthermore, 

 even in organisms which do not have a dissymmetric body form the laevorotatory 

 (natural) isomers of optically active substances (e.g. nicotine and adrenaline) are usually 

 the more toxic. Their effect on the more widely distributed forms of organisms having 

 a dissymmetric body-form is also of this nature. In addition, in molluscs the widespread 

 right-handed form is also more susceptible to the action of laevorotatory acriquine than 

 to that of its optical isomer. The inverse forms of these molluscs are, however, more 

 sensitive to dextrorotatory acriquine. The opposite picture is seen among the soil bacteria 

 B. mycoides with a right-handed spiral colony; a greater proportion of them survive in a 

 medium to which dextrorotatory acriquine has been added than in a medium containing 

 laevorotatory acriquine, that is to say, they behave like the left-handed forms of the 

 molluscs. Studies have also been made of the effect on dextrotropic molluscs of ( + ) and 

 racemic tartaric acids and also of (+)- and ( — )-cinchonine and ( + )-tartaric acid, i.e., 

 just those natural compounds which are most toxic to other organisms. In left-handed 

 molluscs, on the other hand, these compounds were the less toxic. 



These facts are certainly indicative of a definite connection between the dissymmetry 

 of the molecules of optically active reagents and the dissymmetrically constructed receptors 

 in protoplasm (but not the protoplasm itself). The dissymmetry of these receptors then, 

 in some way, affects the external dissymmetrical features of the organisms. 



The examples which have been adduced demonstrate the complexity of the pheno- 

 menon of interaction of dissymmetric factors with living organisms even in cases where 

 one is dealing with receptors for dissymmetric reagents and not with the protoplasm as 

 a whole. A collection of statistical material will show how far such an idea is correct. 



REFERENCES 



1. B. V. Ognev, Vestnik Akad. Med. Nauk S.S.S.R., No. 4, 26, 1948. 



Cf. also Nature, Lond., 169, 232, 1952; 134, 275, 1934; Health Education,No. 3, 1951. 



2. A. V. Shubnikov, Simmetriya i antisymmetrya konechnykh Figur. Moscow: Izd. 



Akad. Nauk S.S.S.R., 1951. 



3. R. Dreiding, Chimia, 11, No. 6, 152, 1957. 



4. W. Ludwig, Das Rechts-Linksproblem im Tierreich und beim Menschen. Berlin, 



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 V. V. Alpatov, Byull. Mosk. Obshch. Isp. Prirody, 58, No. 5, 51, I953- 



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