52 GENETICS 



pendently in four different widely separated localities 

 in California. This, like deVries' evening primrose, 

 was an aggregate mutation, for differences appeared 

 in size, shape, color and texture of leaves ; size, form 

 and color of flower-parts; color of bark, habit of 

 growth, etc. That this was a true mutant and not a 

 hybrid between the oak and the walnut was indicated 

 by negative results in cross-pollinating experiments. 

 Similar aggregate mutations have been reported for 

 cotton, tomato, tobacco and other organisms. 



Another phenomenon that probably indicates com- 

 mon ancestral germplasm among species, at present 

 apparently independent of each other, is the occurrence 

 of parallel mutations. The North African ostrich 

 (Struthio camelus) and the South Australian ostrich 

 (S. australis), although separated from each other for 

 long geological time, show, according to Duerden, 

 similar mutations in size, length of neck and legs, skin- 

 color and bald-head as well as in size and shape of the 

 egg and the character of its surface, whether pitted or 

 ivory-smooth. 



A long list of parallel mutations in Drosophila 

 melanogaster and D. virilis has been described by Metz, 

 and similarly, Sturtevant reiports mutations in D. 

 funebris that are likewise parallel to those of D. 

 melanogaster, in which the occurrence of mutations 

 has probably been more carefully studied than in any 

 other animal. 



Sumner with the deer-mouse, Peromyscus, has found 

 albinism, spotting and red-eyed yellow, all mutations 

 known to occur in other mice. 



