2 3 



VA R I AT I O N 



Fig. 19 



Fig. 19.— Some of the numerous variations in the pattern of the abdomen in the yellow 

 jacket Wasp. [After Kellog and Bell. J 



! 



VAR I ATION 

 Fig.20. 



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

 mullitceniala. The type of the species (2) and its extreme mutants rubicunda (1) and 

 melanothorax (3). [After W. L. Tower.] 



[ Facing p. 76 



