494 SESSION V. DISCUSSION 



Figs. 4 and 5 show spectrograms for coacervatc drops containing nucleic acid (Fig. 4) 

 and without ncuclcic acid (Fig. 5). 



It has been shown that, for a spherical coacervate droplet having a diameter of 29 //, the 

 concentration of nucleic acid is 760 mg "„. This concentration is 15 times greater than 

 that for the coacervate system as a whole, including the equilibrium liquid. Thus the co- 

 acervatc droplets concentrate nucleic acids. The content of nucleic acid found in this 

 particular droplet is of about the same order as that in the nuclei of the cells of mouse liver 

 as determined by Kasperson & Brodskii [3]. 



2. From the works of Kroit and Bungenberg de Jong and his pupils as well as from our 

 own observations during the preparation of complex coacervates composed of proteins, 

 carbohydrates, nucleic acids and enzymes, one might imagine that a coacervate occupies 

 an intermediate position between a colloidal solution and a colloidal precipitate and could 

 be obtained cither from a solution or from a precipitate. Hitherto, however, attention has 

 been mainly directed towards obtaining coacervates from solutions. 



By means of interval micro-cinematography we have succeeded, in collaboration with 

 A. M. Kudryavtsev, in taking a small film of the formation of coacervates from colloidal 

 precipitates. Thanks to such a film wc have been able to study the continuity of the process 

 of development of coacervates from a formless, flocky precipitate into formed coacervate 

 drops (cinema film shown). Figs. 6, 7, 8 and 9 are stills from the film. 



The process of formation of coacervate droplets from the precipitate actually took 

 20 minutes at a temperature of +40-45 C on the warm stage of the microscope. 



On the basis of the material which has been demonstrated, it seems to me that one may 

 put forward the hypothesis that the formation of precipitates might have been a stage in 

 the individualization of substances in the form of coacervate drops. Organic substances 

 were concentrated in these precipitates and served as good material for the formation 

 from them of coacervate drops. 



(Figs. I to 9 appear between pages 496/497) 



REFERENCES 



1. A. I. Oparin, The Origin of Life on the Earth. Oliver & Boyd, Edinburgh, 1957. 



2. T. N. EVREINOVA, Usp. sozremen. Biol., 37, 177, 1954. 



3. T. N. EvREiNOVA, Biofizika, i, 167, 1956. 



V. I. VoROBiEV (U.S.S.R.): 



The Formation of Fibrillar Protein Complexes as a Stage in the 

 Evolution of Structures 



One of the most important trends in the study of the evolution of structures is the 

 production of model systems having more and more compUcated properties. The sugges- 

 tions made in this Symposium by Oparin, Deborin, Macovschii and Tongur show that this 

 is a fruitful method. 



I should like to emphasize that the fundamental components of biological structvires, 

 namely proteins and nucleic acids, are electrolytes of high molecular weight and that, 

 therefore, they can combine very readily to form compHcated complexes. Some years 

 ago we began to study artificial complexes formed by the interaction of deosyribonucleic 

 acid with globular proteins. The structures thus formed had very interesting properties 

 which were absent from each of the components taken separately. They had a definite, 

 morphological individuality and, most importantly, they were demarcated from the 

 medium in which they were formed. Double refraction, mechanical rigidity, very great 

 elasticity and the ability to swell up or be dehydrated were also characteristic of these 

 model systems. These formations, which were similar to coacervates, behaved as a separate 

 phase in relation to the solution around them. It was found that, in accordance with the 

 findings of Oparin, the concentration of various substances in these structures and in the 

 surrounding medium might differ. This might be the property of the fibrillar complexes 



