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THE AMERICAN NATURALIST [Vol. XLVIII 



sex-limited character) to cover that class of cases (obvi- 

 ously a very mixed one which will be broken np as our 

 knowledge regarding it becomes more certain) that in- 

 cludes largely, as originally intended, the secondary sexual 

 characters. 2 In those cases of sex-linked inheritance, in 

 which the male is heterozygous for the sex factor, the 

 grandfather transmits his peculiarity, through his daugh- 

 ters, to half of his grandsons only; and reciprocally an 

 affected female transmits her peculiarity to all her sons, 

 and, through her sons bred to her daughters, to half of 

 her granddaughters and to half of her grandsons 3 . More- 

 over the appearance of the character in the female is not 

 exceptional or abnormal, as is sometimes implied in cases 

 like color blindness in man, for, the character can always 

 be transferred from the male to the female by suitable 

 crosses. 



On the other hand, there are cases in which a character 

 appears in one sex only— the character is limited, there- 

 fore, to the male or to the female. Such cases may be 

 properly called sex-limited, and were so called by Darwin. 

 As typical examples I may cite the horns of certain races 

 of sheep that are present in the ram and absent in the 



