THEORY OF EVOLUTION 



11 



, taken place in the wings and several of these 



' invoh-e the size of the wings. If we arrange 

 the latter arbitrarily in the order of their size 



j there will be an almost complete series begin- 

 ning with the normal wings and ending with 

 those of apterous flies. Several of these types 

 are represented in figure .5. The order in which 



1 these mutations occurred bears no relation to 



^4: * 



\ 





/ 



f-^ 



m. i'!^ 



V 



^ 







Fig. 5. Mutants of Drosophila ampelophila arranged in 

 order of size of wings: (a) cut; (b) beaded; (c) stumpy; 

 (d) another individual of stumpy; (f) vestigial (g) apterous. 



