THE AMERICAN NATURALIST 



[Vol. XLVIII 



a place. One would be inclined to look upon orbicularis 

 as a mutation. But the fact that at first we classed 

 arachnoid <> a as such, later to prove it of hybrid origin, 17 



would tend to make us cautious, and lead us to attempt to 

 find a solution for the origin of orbicularis in the disso- 

 ciation or combination of certain "units." While I should 

 not care to go quite as far as M. Keribert Xilson 18 "das 

 ganze Mutations plianomen durfte unter einen gemein- 

 samen Gesichtspunkte: der Mendelschen Xenkombination 

 eingeonlnet werden konncn," yet it is probable that here 

 the majority of alleged imitations may be classed. 



