378 SESSION IV. DISCUSSION 



A. S. KoNiKOVA (U.S.S.R.): 



To make any progress with the problem of the origin of life, it is necessary to have some 

 definition of the essential properties of this form of existence of matter, i.e. life. 



It has been suggested here by Mr. Pirie, I think, that the definition of the concept of 

 life is arbitrary and conditioned by our aesthetic feelings. However, this conditioning is, in 

 its turn, determined by the facts of the real world which are known to us and by the strict 

 laws of logic. The arbitrariness and conditionality of our conceptions of life are, therefore, 

 only apparent. The impression of arbitrariness depends less on aesthetic feelings and more 

 on the fact that, with the help of the rules of logic, each investigator correlates the existing 

 experimental data and interprets them. The more correctly this work is carried out the 

 closer to objective reaUty our concepts will be. I suggest that the evidence of this Sym- 

 posium will allow such an approach to reality to be made. 



All the facts indicate that, if we do not have recourse to the existence of supernatural 

 forces, then, before the appearance of living things, nothing existed in nature apart from 

 physics and chemistry. 



Prof. Horowitz's communication is therefore profoundly correct in that part in which 

 he maintains that life originates at the level of chemical molecules. It is, however, very 

 hard to agree with his second proposition, that the substances of the surrounding medium 

 were more complicated than the living molecules which were present in it. It is hard to 

 agree with this mainly because, among the objects of non-living nature, there is nothing 

 so comphcated as a hving thing, if we take complication to mean the extensiveness of the 

 possibility of the manifestation of properties by the particular compound. 



As life began on the chemical level it follows that it was also on the level of molecular 

 chemical reactions which assured the minimal difference between chemistry and biology. 

 There is no direct transition from these relatively simple transformations to the organism 

 because to solve the problem of the origin of life it is necessary to explain which chemical 

 substances accomplished the reactions which brought about the minimal transformation 

 which led to the origin of living from non-living material. 



From what we now know of the problem of Ufe three substances must be considered 

 from this point of view, namely nucleoprotein, protein and nucleic acid. 



The claim of nucleic acid to be considered has arisen quite recently, after the work in 

 which it was demonstrated that the tobacco mosaic virus is formed when tobacco leaves 

 are infected with nucleic acid, and also since it has been shown the process of synthesis 

 of nucleic acid can take place even when protein synthesis is prevented. 



It must, however, be remembered that all these phenomena were observed in comph- 

 cated biological systems and, so long as it has not been established experimentally that 

 self-reproduction of the component particles of isolated nucleic acid itself can occur, 

 there is no reason to consider it as being the earliest form of hfe. 



As Engels supposed, protein is of great importance in this connection and later inves- 

 tigations indicate that so is nucleoprotein, because both these substances have been shown 

 experimentally to have the power of independent metabolism in an artificial medium, 

 giving rise to material like and unhkc themselves, which could initiate development. 



Further investigations will show whether the formation of a complex of protein and 

 nucleic acids is necessary to ensure the transition from chemistry to biology. 



According to the evidence of our work this is not necessary; but the properties of pro- 

 teins point in the same direction. The size of the protein molecule, the heterogeneity of 

 its component parts and bonds and the reactivity of proteins are such that their exchange 

 reactions with the substances of the medium are enough, in themselves, to provide for 

 the appearance of the earliest properties of Ufe. 



Analysis of the data already available gives reason for considering that a concentration 

 of attention on the laws of mctaboUsm of the simplest forms of hfe, bordering on chemistry, 

 will open up perspectives for an understanding of the processes of their elaboration and 

 development and also of the transformation of these simplest forms of hfe into the rever- 

 sibly inhibited state, as obviously occurs in the case of an isolated virus. 



M. Grunberg-Manago (France): 



Je voudrais dire juste quelques mots au sujet de la remarque de M. Bresler. Il est très 

 possible effectivement que 1' 'extra' P du polynucleotide synthétisé par l'enzyme de 



