98 KNTRODUCTION TO SEXUAL PHYSIOLOGY 



ostrich breeders in South Africa, the operation is often carried 

 out. It is noteworthy that the castrated male and female ostrich 

 are identical in type. 



In insects, however, there is no correlation between the ovaries 

 and the external female characters any more than betw^een the 

 testes and characters of the male. 



Ovariotomy in women prevents the recurrence of menstruation, 

 or if done before puberty, the menstrual cycle never begins. 

 Similarly with other mammals, the oestrous cycle does not recur 

 in the absence of the ovaries. The removal of the uterus (hyster- 

 ectomy) without the ovaries, on the other hand, does not inhibit 

 oestrus, and the ovaries continue to produce ova and to form 

 corpora lutea, the mammary gland also undergoing cyclical 

 changes. Ovariotomy is sometimes performed on the domestic 

 animals for economic purposes, but not so commonly as castration 

 in the male. In the sow it is done to promote fattening, the 

 pigs feeding better and more regularly, being undisturbed by 

 sexual excitement at the three-weekly periods when oestrus 

 would otherwise occur. Ovariotomy is also done occasionally 

 on vicious or troublesome mares which become unworkable at 

 the oestrous periods especially in the presence of stallions. 



As already remarked in discussing castration, there is some 

 evidence that the removal of the gonads induces fattening by 

 causing a reduction in the metabolism, this having been shown 

 by Murlin and Bailey in the case of bitches. A tendency towards 

 adiposity is sometimes well marked after the menopause or 

 climacteric when there are also other indications of the decline of 

 ovarian influence, as manifested, in the assumption of male (or 

 at any rate neutral) secondary sexual characters (e.g. the tendency 

 to grow hair on the upper lip and chin in elderly women). 



The Internal Secretions of the Ovary 



The evidence that the ovary is an organ of internal secretion 

 is of similar kind to that showing that the testis is such an organ. 

 If the ovaries, instead of being entirely removed, are grafted 

 (or only one is grafted) in an abnormal position, such as the ventral 

 peritoneum or the interior of the kidney, in spite of the fact 

 that the ordinary nerve connections are severed, the uterus, 

 instead of undergoing atrophy, is maintained in its normal 



