HOMOLOGY AND ITS INTERPRETATION 65 



conclusion from our present evidence that upon Weismann's 

 principle we can explain inheritance but not evolution, while 

 with Lamarck's principle and Darwin's selection principle we 

 can explain evolution, but not, at present, inheritance. Dis- 

 prove Lamarck's principle and we must assume that there is 

 some third factor in evolution of which we are ignorant." 

 (Popular Science Monthly, Jan., 1905.) The point is well 

 taken, and unless, as Osborn suggests, there is a tertium quid 

 by means of which the discord can be resolved into ultimate 

 harmony, we see no way of liberating the theory of Transmuta- 

 tion from this embarrassing dilemma. 



