344 



THE PHYSIOLOGY OF REPRODUCTION 



Another spa3'ed duck first assumed the nuptial plumage and then the 

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

 was succeeded hj the nuptial plumage again. Moi'gan ^ sixggests 

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

 have Ijeen retained. 



Duerden- states that ovariotomy in the ostrich is followed by 

 retention of the ordinary body colour, l)ut that the normally grey 

 featliers 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 lien. Thus 



Fig. 86. — Normal Eoueii drake. (From Goodale.) 



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

 similar type (see above, p. 337). 



The effect of ovariotomy upijn the cow has been studied by 

 Tandler and Keller ^ who state that it pi'oduces a type similar to the 

 castrated male (that is to say, it causes a con^•ergence of type in the 

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

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

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



' Morgan, loe. cit. 



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



^ Tandler and Keller, " Die Korperform der Weiblicben Friihkastraten des 

 Eindes," Arch. f. Entv'icl\-Mech., vol. xxxi., 1910. For effect on cats, .see above, 

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



^ Pearl and Surface, Hex HtmJiea, VII., Orono, Maine, 1915, 



