268 



The singular but logical result of this closely-reasoned train of 

 :argument is that all congenital variations of multicellular organ- 

 isms are really and actually the remote consequences of difierences 

 stamped upon their primeval unicellular ancestors by variations 

 in their surrounding conditions of life. 



Such is an outline of Weismann's theory as put forth in the 

 series of essays alluded to. Many objections have been, and are 

 still being, raised to some of his facts and arguments, and even 

 the author himself has modified some of his views since they were 

 first enunciated. Taken as a whole, these essays constitute a re- 

 markable addition to the literature of evolution, and the conclu- 

 sions to which they lead have already exercised a profound in- 

 fluence on the current of modern biological thought, and are des- 

 tined, I think, to bear still further fruits. 



