SESSION I. DISCUSSION 109 



While we are considering the catastrophic consequences of a significant increase in 

 the intensity of cosmic radiation in bygone periods in the development of the Earth, we 

 must mention that this factor could have stimulated the formation, from primitive organic 

 compounds, of those complicated complexes from which life could have originated on 

 the Earth. 



REFERENCES 



1. I. S. Shklovskiï, Dokl. Akad. Nauk S.S.S.R., 90, 983, 1953. 



2. J. OoRT & T. Walraven, Bull. astr. Insts Netherlds, 12 (462), 285, 1956. 



3. R. Hanbury Browtn & C. Hazard, Nature, Lond., 170, 364, 1952. 



4. J. Shakeshaft, M. Ryle, J. Baldwin, B. Elsmore & J. Thomson, Mem. R. Astr. 



Soc, 67 (3), 106, 1955. 



5. D. Walsh & R. Hanbury Brown, Nature, Lond., 175, 808, 1956. 



6. I. S. Shklovskiï, Kosmicheskoe radioizluchenie. Moscow (Gostekhizdat), 1956. 



7. J. Thanerey, Observatory, 76, 311, 1956. 



8. N. P. Dubinin, Vestnik Akad. Nauk S.S.S.R. (8), 22, 1956. 



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



The Question of the Primary Synthesis of Organic Substances on the Earth 



According to a widely held view, 3000-4000 miUion years ago, when the transition 

 from the magmatic stage of development of the Earth to the present geological stage 

 was completed, the temperature on the surface of the planet was so high that all organic 

 substances, if any were present by that time, must have been given off into the atmosphere. 

 We must therefore reckon that absence of free oxygen in the atmosphere of the planet 

 was a necessary condition for the occurrence of the primary synthesis of organic com- 

 pounds and for their continuing to exist and being transformed. 



In picturing the protoplanetary system, investigators have argued that the mass of 

 hydrogen in the protoplanetary cloud was greater than that of oxygen. However, it is 

 far from being proved that after the long period of development of the planet preceding 

 the stage of magmatic coohng, there was the same lack of free oxygen as there had been 

 earUer. 



An attempt will be made here to show that the ratio between the amounts of hydrogen 

 and oxygen in the atmosphere changed in favour of hydrogen soon after the formation 

 of the crust of the Earth, so that conditions became favourable for the occurrence of the 

 primary synthesis and retention of its products. 



Judging from the temperature of crystalUzation of magmatic formations the tempera- 

 ture of the surface of the Earth must, at some time, have been not less than 1600 °C. 

 The liquid incandescent surface of the magma was, at that time, surrounded by a very 

 large atmosphere. Exchange of gases between the magma and the atmosphere took place 

 comparatively easily. However, with the appearance of the solid crust of the Earth, the 

 exchange of gases between the planet and its atmosphere became considerably more 

 difficult. From the moment of its formation, the crust of the Earth constituted a barrier 

 and a bed for the substances which condensed and were deposited on the surface of the 

 planet during its later cooling. Basing ourselves on the mass of the lowest-boiling com- 

 ponents of the crust of the Earth we may calculate the approximate composition of the 

 atmosphere at the end of the stage of magmatic coohng of the planet. Such a calculation 

 gives the probable percentage composition of the atmosphere as: water 80-90, carbon 

 dioxide 12-15, phosphorous anhydride o-5-io, nitrogen 005-01 and other com- 

 ponents 0-0I-0-02. 



The gases of the atmosphere were dissolved in the magma in considerable amounts 

 determined by their partial pressures and solubilities. It is important to note that water 

 vapour, being the main component of the atmosphere, was contained in large amounts 

 in the magma. 



