Place of Definition, etc., m Philosophical Biology 119 



It signifies many things, one of which particularly 

 concerns us now, and may be put into the following 

 general proposition: No biological phenomenon is ade- 

 quately interpreted or dealt with experimentally, until 

 it has been considered with reference to the place that 

 the organisms to which it pertains hold in the system of 

 classification. To illustrate, no generalization about 

 the chromosomal structure and behavior in the sperma- 

 togenesis of species # of genus a can be accepted as 

 fully valid until compared with the chromosomal struc- 

 ture and behavior of species m, n, o, p, etc., of the 

 same genus. And a like restriction must be placed on 

 generalization about the reaction of species x to light, 

 or to any other stimulus, or to its distribution in na- 

 ture, and so on. 



To undertake the recital of special researches in 

 support of this proposition would be to undertake the 

 review of most of the recent investigations in the prov- 

 inces of biology mentioned. And notice this : The re- 

 sults of these researches look in the direction indicated 

 despite the fact that in most cases the studies had little 

 or no systematic aim. The great amount of evidence 

 of this purport is mostly incidental to other motives 

 of investigation. 



I would not be understood as advancing the hypoth- 

 esis that every species of plants and animals differs 

 from every other species to some extent in every attri- 

 bute. What I affirm is that the inductive evidence has 

 now gone so far toward proving every sharply differ- 



