FOUNDATIONAL AGES 



ACCORDING to the Nebular Hypothesis the solar system 

 was evolved from a vast gaseous mist or nebula. This rarefied 

 and intensely heated matter was the outcome, it is supposed, 

 of a collision between extinct suns or other once-luminous 

 bodies. In course of time, owing to loss of heat by radiation, 

 concentrations took place in various parts of the vapour. 

 And the Earth and other planets gradually emerged as 

 molten bodies moving round a great central concentration 

 the forming sun. 



As the result of radiation our planet in time became 

 so far deprived of heat as to gain a superficial crust or cover- 

 ing. The heat of the crust, however, must for long have con- 

 tinued so intense as to be beyond the reach of any rainfall 

 from the primitive atmosphere. 



Owing to continued fall in temperature the crust must 

 have increased in solidness. And a time came when the lower 

 levels of the cooled and crumpled surface became the resting- 

 places of long-pent-up rains, no longer repulsed by an ex- 

 cessive heat. The Earth had its sea and land. 



The heat of both elements was for a long time probably 

 too intense for life, as man understands it, to become manifest ; 

 but to what point temperature had fallen when the first 

 forms of life appeared, is quite unknown. In this connection, 

 however, it is a matter of interest that plants have been 

 discovered living in thermal springs of a temperature of 

 170 Fahr., and in heat of 260 Fahr. some spores have been 

 found to retain vitality. 



Of the earliest life-forms nothing, of course, is known. 

 They probably originated in the shallow waters of the primeval 

 seas ; and may well have been excessively minute. Indeed 



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