No. 5(34] 



OF CHARACTER 



711 



being exterminated seems to prove that there is no corre- 

 lation between the vigor and adaptability of the organism 

 and its conservative structural characters. 



Darwin maintains that the constancy of useless fea- 

 tures "chiefly depends on any slight deviation not having 

 been preserved and accumulated by natural selection 

 which acts only on serviceable characters";-"' but if all the 

 characters and structures of any particular group were 

 originally variable in the same degree, a supposition which 

 the theory of natural selection is usually regarded as mak- 

 ing, it is surely impossible to suppose that variations will 

 not be most strikingly manifest in just those features 

 whicli are not subject to the eliminating action of natural 

 selection. 



Simple and plausible as the selection theory is. we must 

 admit that it offers by no means a complete solution of 

 the problem of fixity since, in general, the conservatism of 

 a structure or character seems to be inversely rather than 

 directly proportional to its survival value. To reach a 

 better understanding than such a theory gives as to why 

 variation does not occur with equal frequency and extent 

 throughout all parts of an organism, we must first of all 

 endeavor to formulate, from the great mass of facts at 

 band, such general laws of variabilis and conservatism 

 as we may be able to discover empirically and must then 

 try to explain them as well as we may. A survey of the 

 fields of taxonomy and comparative anatomy shows the 

 possibility of discovering in the evolutionary develop- 

 ment of organisms the presence of numerous uniformities 



