Mutating Species 



Java, and Bicheno's Finch (S. bichenovii) of 

 Australia, only differ in the former having the 

 rump black, while in the latter it is white, and 

 this difference appears to be of the nature of a 

 mutation. 



So, it might be urged, is the pure white breast 

 of the male Upland Goose (Chloephaga magel- 

 lanicd), which part, in the very similar C. dispar, 

 is barred as in the females, the latter form being 

 probably the ancestor. 



The differences between the silver-grey-necked 

 Crowned Crane of the Cape (Balearica chryso- 

 pelargus) and the dark-necked species of West 

 Africa (B. regulorum) seem also to be not more 

 than could be accounted for by mutation. 



Peculiar forms, such as a rabbit with a con- 

 voluted brain or a mouse with a peculiar pattern 

 of molar teeth, have been come upon by 

 anatomists. 



The above-cited mutations are all very con- 

 siderable ones, and we do not profess to have 

 mentioned a tenth part of those which have 

 actually been recorded. 



We trust that we have collected and set forth 

 sufficient evidence to show that the phenomenon 

 of discontinuous variation is a very general one, 

 and this would seem to tell against the hypo- 

 thesis of De Vries that species pass through 

 alternate periods of comparative stability and 

 periods when swarms of mutations appear. We 



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