226 THE DESCENT OP MAN. 



tween great sexual dissimilarity and complete similarity. In- 

 stances have already been given with the breeds of the fowl and 

 pigeon, and under nature analogous cases are common. With 

 animals under domestication, but whether in nature I will not 

 venture to say, one sex may lose characters proper to it, and may 

 thus come somewhat to resemble the opposite sex; for instance, 

 the males of some breeds of the fowl have lost their masculine tail- 

 plumes and hackles. On the other hand, the differences between 

 the sexes may be increased under domestication, as with merino 

 sheep, in which the ewes have lost their horns. Again, characters 

 proper to one sex may suddenly a,ppear in the other sex; as in those 

 sub-breeds of the fowl in which the hens acquire spurs whilst 

 young; or, as In certain Polish sub-breeds, in which the females, 

 as there is reason to believe, originally acquired a crest, and sub- 

 sequently transferred it to the males. All these cases are intelli- 

 gible on the hypothesis of pangenesis; for they depend on the 

 gemmules of certain parts, although present in both sexes, becom- 

 ing, through the influence of domestication, either dormant or de- 

 veloped in either sex. 



There is one difficult question which it will be convenient to 

 defer to a future chapter; namely, whether a character at first de- 

 veloped in both sexes, could through selection be limited in its de- 

 velopment to one sex alone. If, for instance, a breeder observed 

 that some of his pigeons (of which the characters are usually 

 transferred in an equal degree to both sexes) varied into pale blue, 

 could he bj' long-continued selection make a breed in which the 

 males alone should be of this tint, whilst the females remained 

 unchanged? I will here only say, that this, though perhaps not 

 impossible, would be extremely diflicult; for the natural result of 

 breeding from the pale-blue males would be to change the whole 

 stock of both sexes to this tint. If, however, variations of the de- 

 sired tint appeared, which were from the first limited in their 

 development to the male sex, there would not be the least dif- 

 ficulty in making a breed with the two sexes of a different color, 

 as indeed has been effected with a Belgian breed, in which the 

 males alone are streaked with black. In a similar manner, if any 

 variation appeared in a female pigeon, which was from the first 

 sexually limited in its development to the females, it would be 

 easy to make a breed with the females alone thus characterized: 

 but if the variation was not thus originally limited, the process 

 would be extremely difiicult, perhaps impossible." 



"' Since the publication of the first edition of this work, it has been 

 highly satisfactory to me to find the following remarks (the 'Field.' 

 Sept. 1872) from so experienced a. breeder as Mr. Tegetmeier. After 

 describing- some curious cases in pigeons, of the transmission of color 

 by one sex alone, and the formation of a sub-breed with this char- 

 acter, he says: "It is a singular circumstance that Mr. Darwin 



