LECTURES IN BIOLOGICAL SCIENCES 



gested a slightly different scheme in which many lesser conden- 

 sations that resembled asteroids first formed. These had no 

 atmosphere and were not hot. Gradually they collided to form 

 large masses whose elliptical orbits swept out large volumes of 

 space around the sun. Notice that here also the lighter gases 

 would be largely lost as the new planet formed, but that no ex- 

 cessive heating occurred, at least on the planetary surface. The 

 planets so molded retained some of the carbon compounds 

 formed in space. In fact, it has been proposed that the organic 

 compounds from the protoplanetary cloud played a decisive 

 role in the origin of oil deposits on earth (Fesenkov, 1957). 

 Thus, we are left with an earth devoid of atmosphere, with no 

 surface water, but containing many carbon or "organic" com- 

 pounds, and no life. Leakage of gases from the interior of the 

 earth gave rise to the present atmosphere. In fact, this leakage 

 still continues. The question of whether oil and associated 

 gases are of vital or nonvital origin has been the subject of dis- 

 cussion extending over the last century. Some evidence now 

 supports the conclusion that most deposits antedate the appear- 

 ance of life and have been gradually seeping to the surface for 

 millions of years. Water, which may also have been occluded 

 in rocks and deep geological formations, rose to the surface 

 faster, however, and gave rise to the early oceans. At a depth 

 of 7 to 14 miles water may make up as much as 10% of the 

 total weight of rock (Fesenkov, 1957). To release the amount 

 of water now observed in the oceans, a granite layer must have 

 been extruded that was 14 to 20 miles thick. The earth's crust 

 is actually of this approximate thickness. Thus, we have a 

 planet with liquid water condensed into primeval oceans, turn- 

 ing on its axis often enough to avoid extremes of temperature, 

 and containing at the very outset some carbon compounds. The 

 primeval atmosphere— still a matter of considerable discussion- 

 was most probably composed of hydrogen, ammonia, methane, 

 a small amount of CO.,, and water (Urey, 1952). The question 

 arises, will any compound of interest to us be formed when 

 such an atmosphere is irradiated by the intense solar ultraviolet 

 irradiation? To examine this point, Miller, at Urey's sugges- 

 tion, placed a mixture of H 2 , NH :H , CH 4 , and water in a closed 

 vessel, sterilized it, and then generated ultraviolet light inside 



