172 BLASTOGENIC VARIATIONS. 



stances of the ancon or otter sheep * and japanned or 

 black-shouldered peacocks,f quoted by Darwin, are the 

 most striking. The originator of the ancon breed of 

 sheep was a single ram, born in Massachusetts in 1791. 

 Ancon rams and ewes invariably produced ancon off- 

 spring, whilst when crossed with other breeds the off- 

 spring resembled either parent, and only very excep- 

 tionally yielded intermediate forms. Japanned pea- 

 cocks, which differ conspicuously from the common 

 peacock in colouring, appear suddenly in flocks of the 

 common kind. Though smaller and weaker birds, they 

 have been known in two instances to increase, and finally 

 extinguish the previously existing breed. They would 

 therefore seem to have been strongly prepotent. 



That sports may be no more transmissible than other 

 variations seems to be true in the case of polydac- 

 tylism, for Dr. Struthers asserts that cases of non- 

 inheritance and of the first appearance of additional 

 digits in unaffected families are much more frequent 

 than cases of inheritance. J Again, Galton regards as 

 sports the mental arithmeticians and eminent musi- 

 cians who are occasionally born into families which in 

 previous generations have shown no signs of such ex- 

 ceptional characters. Though these characters may 

 be transmitted to descendants, yet this is the excep- 

 tion, and not the rule. The subservience of sports 

 to the law of hereditary transmission is well shown 

 by some observations of Standfuss on Lepidop- 

 tera. In 1888 a normal female Aglia tau was crossed 



* " Animals and Plants," i. p. 104. 

 |Z. c., i. p. 305. 

 \L. c., i. p. 458. 



