2 3 



VAR IATION 



Fig.19 



FIG. 19. Some of the numerous variations in the pattern of the abdomen in the yellow 

 jacket Wasp. [After Kellog and Bell. ] 



VAR IATION 

 Fig.20. 



FIG. 20." Mutations " or rapidly developing large inheritable variations in Leptinotarsa 

 multitceniata. The type of the species (2; and its extreme mutants ruhiatnda (1) and 

 melanothorax (8). [After W. L. Tower.] 



[Facing p. 76 



