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THE AMERICAN NATURALIST [Vol.XLIX 



dog." It would be a distinct gain to breeders if they 

 could reduce the variation in details of the English pat- 

 tern so that "prize-winners" could be bred without the 

 production of so many "wasters," which depart in essen- 

 tial points from the standard pattern adopted for the 

 breed. This was an additional reason for undertaking 

 work with the English rabbit. 



The first standard-bred English rabbits which the 

 senior author had under observation, when mated inter se, 

 produced young of three sorts. About half the young 

 were fairly good "standard" English extensively marked 

 with colored spots (see Fig. 3). About one fourth were 

 much whiter than the standard demands, their spots being 

 fewer and smaller (see Fig. 1). And the remaining 

 fourth were without spots, that is, were self colored. 

 This last class was found to be recessive and not to pro- 

 duce English offspring, if mated inter se. 



The whiter-than-standard English proved to be homo- 

 zygous for the pattern, the "standard" English being 

 heterozygous and breeding like their parents. 



From these observations it was clear (1) that the Eng- 

 lish pattern is a Mendelian dominant and (2) that the 

 breeding of English rabbits resembles that of blue 

 Andalusian fowls. For the standard-bred animal is a 

 heterozygote in the production of which there is bound 

 to be a constant production of "wasters" unless either 

 the standard is changed or the homozygote can be changed 

 to conform with the standard, producing an animal with 

 more color. In the latter case homozygotes could be 

 bred with each other and wasters eliminated. The ques- 

 tion whether the pattern can be changed becomes there- 

 fore one of practical as well as theoretical interest. 



In making crosses of English with other breeds of 

 rabbits, there was found to be considerable variation 

 among the heterozygous English produced, some being 

 much whiter than others, i. e., having less extensive 

 colored spots. Plus (dark) and minus (light) selections 

 were made to see to what extent the pattern was capable 



