338 Prof. A. Giard on Parasitic Castration 



species. Ill the case of the hen pheasant tliis has been ob- 

 served to occur more frequently during certain seasons than 

 during others [Yarrell, Phih Trans. 1827 ; Dr. Hamilton, 

 P. Z. S. 1862J. A duck ten years old has been known to 

 assume both the perfect winter and summer plumage of the 

 drake. Waterton [Essays, 1838] gives a curious case of a 

 hen which had ceased laying and had assumed the plumage, 

 voice, spurs, and warlike disposition of the cock ; when 

 opposed to an enemy she would erect her hackles and show 

 fight. Thus every character, even to the instinct and manner 

 of fighting, must have lain dormant in this hen as long as her 

 ovaria continued to act *. The females of two kinds of deer, 

 when old, have been known to acquire horns." 



Lastly, every one knows that in many women after the 

 cessation of menstruation the chin and upper lip become 

 clothed with a regular beard, a phenomenon the relation of 

 which to the development of the male plumage in old hen 

 pheasants cannot be denied. 



"On the other hand," says Darwin (I.e.), "with male 

 animals, it is notorious that the secondary sexual characters 

 are more or less completely lost when they are subjected to 

 castration. Thus, if the operation be performed on a young 

 cock, he never, as Yarrell states, crows again ; the comb, 

 wattles, and spurs do not grow to their full size, and the 

 hackles assume an intermediate appearance between true 

 hackles and the feathers of the hen. Cases are recorded of 

 confinement alone causing analogous results. But characters 

 properly belonging to the female are likewise acquired ; the 

 capon takes to sitting on eggs, and will bring up chickens ; 

 and, Avhat is more curious, the utterly sterile male hybrids from 

 the pheasant and the fowl act in the same manner, ' their 

 delight being to watch when the hens leave their nests and 

 to take on themselves the office of a sitter.' That admirable 

 observer Reaumur asserts that a cock, by being long confined 

 in solitude and darkness, can be taught to take charge of 

 young chickens ; he then utters a peculiar cry, and retains 

 during his whole life this newly acquired maternal instinct. 

 The many well-ascertained cases of various male mammals 

 giving milk show that their rudimentary mammary glands 

 retain this capacity in a latent condition." 



We have cited textually these passages from Darwin, of 

 which the conclusion is that " t7i mant/, probably in all, cases, 

 the secondary characters of each sex lie dormant or latent in 



« " Isld. Geoffroy St.-Hilaire in his ' Essais de Zool. Gen.' (1842), has 

 collected such cases in ten dift'erent kinds of birds. It appears that Aris- 

 totle was well aware of the change in mental disposition in old hens." 



