10 THEORY OF EVOLUTION 



ity. This conclusion is not necessarily con-ect. 

 Let nie give some examples that have come 

 under my own ohservation. We have hred for 

 five years the wild fruit fly Drosophila ampelo- 

 phila (fig. 4) and we have found over a hun- 





Fig. +. Drdsojihila anipelojihila. a. Female and b, male. 



dred and twenty-five new types that breed true. 

 Each has arisen independently and suddenly. 

 Every part of the body has been affected by 

 "/ one or another of these mutations. For in- 

 stance many different kinds of changes have 



