ORIGIN OF SPECIES 236 



Geological records clearly show that the earth 

 passed through at least several great periods of well- 

 nigh general upheaval and changes of continental 

 surfaces. The end of every one of these great epochal 

 periods provided a maximum of the conditions which 

 according to the theory are necessary for the initia- 

 tion of life. 



A critical concentration of ions always develops 

 whenever the conditions permit; and the formation 

 of dual-systems, according to the theory, always 

 occurs whenever the conditions permit. 



As it has been shown, geology indeed testifies that 

 following the several great periods of upheaval which 

 were attended by destruction (seemingly verging on 

 extinction) of life on land, new and higher life-forms 

 made their relatively abrupt appearance. 



The cause of the successive appearance of higher and 

 higher life-forms on the earth during geologic time is 

 found, I hold, in the fact that each succeeding time in 

 the earth's history which was favorable to the wholesale 

 origin of life provided greater complexity of conditions 

 {physicochemical cojiditions) than the preceding times. 



In extensiveness some of the great occasions that 

 were favorable for the repeated wholesale origin of 

 life, approach that of the early earth. But without 

 a doubt, each succeeding occasion had greater com- 

 plexity. Geologists and paleontologists (Walcott, 



