SESSION IV. DISCUSSION 381 



the gene. Without embarking on a criticism of this conception as a whole, I would remark 

 that the attempt to associate a hypothesis about the primary Uving structure with one 

 about the material carriers of heredity is not new. In the book already mentioned. 

 Academician Oparin rightly pointed out that the concepts of 'idioplasm', 'biogenes', 

 'plastomes' and so on, of earUer authors included not only the idea of a unit of heredity, 

 but also that of the elementary unit of Hfe, the 'Uving molecule'. 



Surely one cannot doubt the obvious suggestion that the original organic material, which 

 manifested the earUest elementary characteristics of living material, also had the ability 

 to hand on hereditary characteristics. Such an inalienable feature of living material as the 

 reproduction of material like itself, which is a prerequisite for the maintenance of Hving 

 material, and also the ability to change as conditions change, must have originated along 

 with the origin of life. 



It must be emphasized that it is only the genetic theory of Michurin which regards 

 heredity as an inalienable property of living material. This theory denies the existence of 

 any special carriers of heredity, whether they are supposed to be in the nucleus or the 

 cytoplasm. The proponents of so-called 'classical genetics' have a different idea of heredity, 

 believing it to be connected with special carriers, i.e. genes. I am not going to deal, here, 

 with the fundamental changes, which have taken place during the last 20 years, in the 

 chromosomal theory of heredity. At present, while dismissing the gene as a corpuscle of 

 a chromosome, geneticists put forward the molecule of deoxyribonucleic acid (DNA) 

 as the unit of heredity, ascribing genetic properties to it. 



This idea has also been emphasized in a number of contributions to our present meeting. 

 In particular. Prof. Belozerskii not only ascribes a genetic role to DNA, but, in developing 

 the idea of the evolution of nucleic acids, he sees it as taking place from ribonucleotides 

 to ribonucleic acid (RNA) and then on to the appearance of DNA. According to Prof. 

 Belozerskii this is what determines the genetic pecuUarities of RNA and DNA. The 

 former is associated with the more general aspects of the vital activity of the organism, 

 while the latter is associated with the narrower and phylogenetically more recent pro- 

 perties of the organism. It must not be forgotten that this is no new idea, although it is 

 given a new formulation. In the twenties of the present century Prof. FiUpchenko took 

 the view that the cytoplasm passes on the characteristics of higher systematic categories 

 while he ascribed to the nucleus the role of carrying the species and racial characteristics 

 of the organism. This hypothesis has not been accepted by geneticists and has been justly 

 criticized. 



I am glad to point out that, both in Academician Oparin's monograph and in many of 

 the papers, many suggestions have been made concerning the question on which I am 

 touching. It will undoubtedly play a great part, not only in the study of the origin of hfe, 

 but also in genetics. From what has been said it clearly follows that, however important 

 the part played by nucleic acid in biological processes, its molecule was not the original 

 basis of life. It is not a 'hving molecule' but one of the parts of a Uving structure which 

 can only fulfil its biological function against the general background of metabolic processes 

 taking place within the cell. The synthesis of the protein molecule depends on nucleic 

 acid just as much as the synthesis of the latter depends on the protein molecule. This is 

 quite understandable. Living material is a complex of compounds which determine the 

 regular course of the processes which constitute Ufe. One cannot isolate an individual 

 component without interfering with the living material, stiU less can one understand Ufe 

 on the basis of such an isolated component, however thoroughly its functions may have 

 been studied. The same appUes to the phenomenon of heredity as well and, in general, 

 to any property of Uving material. 



