SESSION II. DISCUSSION 175 



of racemates occurs under the influence of previously existing optically active substances 

 such as solvents, etc.; while absolute asymmetric synthesis takes place also in the presence 

 of previously existing optically active catalysts or enzymes, alkaloids, optical isomorphs 

 of quartz etc., on the surfaces of which one antipode is adsorbed or reacts more quickly 

 than the other. The action of circularly polarized light is also very important. In my own 

 contribution I wished to draw attention to the importance, in this connection, of recent 

 achievements in the production of stereospecific or so-called isotactic polymers having a 

 determinate spatial arrangement of their side groups. In his interesting work with Ziegler's 

 catalyst [A1(C2H5)3 + TiCli] Professor Natta has shown that, on this catalyst, which 

 is not itself optically active, one may, owing to the oriented adsorption of phenyl groups, 

 obtain molecules of polystyrene with a strictly regular spatial disposition of side groups 

 Alongside the ordinary vinyl polymer, in which the L- and D-configurations are arranged 

 at random, there are formed long series of L-forms alternating with series of D-forms. 

 In the work of Akabori and his colleagues, as Oparin stated in his recent book, aldehydes 

 react with polyglycine adsorbed on the surface of kaolin in its cw-form. This should 

 lead to all the amino acid residues which are synthesized into any one chain having 

 the same spatial configuration. The oriented adsorption of monomers may not in itself 

 have been significant, but the arrangement of the links of the chain of the polymer relative 

 to one another was fixed and the conditions of maximal saturation of the bonds between 

 the side groups and the closeness of the packing may have led to a specific type of twisting 

 of the polymeric chains (e.g., the spiral configuration proposed by PauUng and Corey), 

 and this might have been an important step on the way to pure asymmetric synthesis. 

 In the presence of catalytic substances structures of this kind which themselves possessed 

 catalytic properties, might act as primitive enzymes evoking asymmetry like those, for 

 example, of which Klabunovskiï spoke in his paper. Thus it is possible that asymmetry 

 did not arise because optically active monomers were first formed and optically active 

 polymers were then formed from them but, on the contrary, stereospecific polymerization 

 led to the formation of catalysts of high molecular weight which evoked asymmetry. 

 Later, on account of these catalysts, optically active substances of low molecular weight 

 began to be prevalent. Thus these latter would be, essentially, of secondary origin. As 

 Klabunovskiï has already stated, the appearance of optical asymmetry in an organism 

 was important in that it hastened reactions within that organism and thus favoured its 

 evolution. 



E. I. Klabunovskiï & V. V. Patrikeev (U.S.S.R.): 



Some Questions of Symmetry and Asymmetry in the Animal and 

 Plant Worlds 



Bilateral symmetry of the body is very prevalent among higher animals. This means 

 that the right and left halves of their bodies are mirror images of one another. The internal 

 organs of these animals are, however, often arranged asymmetrically, and this is un- 

 doubtedly determined by the history of the development of the living world [i]. The 

 bilateral symmetry of the form of the body of animal organisms is a result of the adapta- 

 tion of relatively highly organized beings to their conditions of life, requiring directed 

 participation in the inorganic natural world around them which is, on the whole, sym- 

 metrical [2, 3]. However, as well as these, there are organisms which, for the most part, 

 lead a sessile life, and which have asymmetrical bodies; among these are, for example, 

 shrubs and trees among plants and gastropod molluscs among animals. Such organisms 

 manifest so-called enantiomorphism so that they can exist in two independent dissym- 

 metric forms. A large collection of factual material concerning the extensive prevalence 

 of dissymmetry in the animal and vegetable kingdoms has been assembled in his book by 

 the zoologist Ludwig [4]. 



The conditions for the existence in nature of either the one or the other of two dissym- 

 metric forms are identical and one would therefore expect that both forms would be 

 equally distributed in nature. In many cases, however, only one form is prevalent. What 

 is the reason for this? It is known that the molecules of proteins and carbohydrates, which 



