344 



THE PHYSIOLOGY OF REPRODUCTION 



Another spayed duck first assumed the nuptial plumage and then the 

 eclipse plumage of the breed in question, and this in turn (in autumn) 

 was succeeded by the nuptial plumage again. Morgan 1 suggests 

 that in the latter case a slight amount of ovarian tissue might 

 have been retained. 



Duerdeu 2 states that ovariotomy in the ostrich is followed by 

 retention of the ordinary body colour, but that the normally grey 

 feathers assume the blackness of the cock. This fact is taken 

 advantage of by some African farmers, seeing that the plumage of the 

 male is far more valuable economicallv than that of the hen. Thus 



FIG. 86. Normal Rouen drake. (From Goodale.) 



the effects of castration in both male and female are to produce a 

 similar type (see above, p. 337). 



The effect of ovariotomy upon the cow has boon studied by 

 Tandler and Keller 3 who state that it produces a type similar to the 

 castrated male (that is to say, it causes a convergence of type in the 

 manner described by Pezard for fowls). The height of the spayed 

 animal is said to be less than that of the cow. The head is similar 

 to the steer's head. Pearl and Surface 4 have recorded the assumption 



1 Morgan, loc. cit. 



2 Duerden, loc. fit. (see above, p. 337). 



:| Tandler and Keller, " Die Korperform der Weiblichen Friihkastraten des 

 Rindes," Arch. f. B*ttmck.-M0ck. t vol. xxxi., 1910. For effect on cats, see above, 

 footnote, p. 340. And see footnote, p. 358. For sheep, see final footnote, p. 392, 



4 Pearl and Surface, Se.r Studies, VII., Orono, Maine, 1915, 



