6 HERBERT SPENCER AND 



promulgated during the last fifty years, as explanations 

 of vital phenomena ; particularly of the phenomena of 

 specific transformation, of inheritance and variation. 

 T he theory of organ ic Evolution was of jv itaLaJm- 



portance_JtO — liftrhf^rt >^ppnrpr'g whnU phTlngnphiral 



s ystem. His interest in biology was at least equal to 

 his mterest in sociological questions. He contributed 

 new and important ideas to biology, and to the end of 

 his days was engaged in active controversy with Weis- 

 mann, whose theory of the germ-plasm undermined 

 some of his most important positions. It is assumed, 

 perhaps a little too readily, that Weismann came off 

 victorious in the contest, and I shall devote the rest 

 of this lecture to a re-examination of the questions at 

 issue between these two great antagonists, in the light 

 of some recent zoological experiments. 



I have not the time, and I do not think it is necessary, 

 to give references and quotations; but it is, I think, 

 a fair summary of Herbert Spencer's philosophical 

 treatment of biological phenomena, to say that, for him, 

 evolution is, in all its forms, a becoming of the hetero- 

 geneous and complex out of the homogeneous and simple. 

 Thus, in his First Principles, he begins with a considera- 

 tion of chemical and physical laws, and after treating 

 of the interaction of these laws in the production of 

 inorganic phenomena, he proceeds to apply the same 

 principles to the solution of the problems offered by 

 organic phenomena. I may give one quotation to 

 illustrate his point of view. 



' The formation of molecules more and more hetero- 

 geneous during terrestrial evolution has been accompanied 

 by increasing heterogeneity in the aggregate of com- 

 pounds of each kind, as well as an increasing number of 

 kinds ; and this increasing heterogeneity is exemplified 

 in an extreme degree in the compounds, non-nitrogenous 

 and nitrogenous, out of which organisms are built. So 

 that classes, orders, genera, and species of chemical 



