THE BEGINNINGS OF LIFE. 103 



change, other things equal, in direct proportion to the 

 simplicity of their organization. We are driven to the 

 conclusion, in fact, that the simpler the organisms 

 with which we have to deal, the weaker will become 

 the influence of Heredity; and that in independent or 

 new-formed living matter this conservative tendency 

 would be no more potent than it is in crystalline 

 matter. 



This legitimate conclusion once arrived at, the con- 

 sideration of a most important problem is forced upon 

 us. What explanation, it may be asked, is to be given 

 of the existence of multitudes of the lower forms of 

 life at the present stage of the earth's history? It 

 seems only possible to account for their presence by 

 one or other of two explanations. Each of these we 

 will briefly consider. 



I. Theory of Homogenesis, 



Those who disbelieve in the occurrence of Archebiosis 

 and of Heterogenesis — the disciples and advocates, in 

 fact, of the biological doctrines at present most widely 

 accepted — would have us believe that no independent 

 evolution of life has taken place upon our globe since a 

 period shrouded in the far-remote depths of geologic 

 time. Since many of these are willing to admit that 

 progressive specific transitions have continually been 

 taking place through these ages, and that all the various 

 forms of life which have ever clothed the earth are to 

 be considered as representatives of such developmental 



