GEOGKAPIirCAL DISTRIBUTION. 121 



hand, if wc look alone to the relations of organisms to envi- 

 ronment, this set of conditions appears sufflcient to account 

 for the ct)urse of evolution, because in both cases we find 

 adjustment of morpholoijical character to the conditions pre- 

 existing^" at the beginning of each indix^dual life. 



Two Factors Producing the Effects of Evolution. — Assuming 

 these definiticMis to be formulations of the truth in the case 

 to such a degree of accuracy that they may be adopted as 

 working h}'potheses, the next step in our analysis is to ascer- 

 tain what part each of these factors plays in bringing about 

 differentiation of organic form and structure. 



Three Views Possible. — There is practically but one of three 

 opinions to take in the matter: either (i) the differences ob- 

 served among organisms are accounted for entirely by ances- 

 try — that is, the potency of all organic differentiation and 

 evolution is found in the ancestry at any particular moment 

 of the process; or (2) environment is the efficient factor in 

 bringing about all modification of organic structure; or (3) the 

 actual course of evolution as it takes place is the resultant of 

 the co-operation and antagonistic action of both factors. 



The extreme old school (of Cuvier, for instance) adopted 

 the first opinion, the extreme natural selection or Darwinian 

 school holds substantially the second view. It is believed by 

 the author that the truth will be found in the third position. 

 First Cause of some sort Essential to any complete Theory of 

 Evolution. — The discussion of evolution has for the past fifty 

 years chiefly centred about the theory of the origination of 

 species. Ancestry, in the general sense here used, includes 

 all the antecedent intrinsic conditions of an individual life. 

 When we analyze the theories to their ultimate essence the 

 great contrast between Creationism and Evolutionism does 

 not lie in the fact that the one acknowledges God to be the 

 first cause or ultimate ancestor of every living thing, while 

 the other, in magnifying the agency of the environment in 

 controlling the origin of species, denies all first cause : for, in 

 both cases, some pre-existing power or potency that is quite 

 godlike must be assumed as the necessary antecedent to the 

 phenomenal appearance of organisms in all their variety upon 

 the earth. 



