128 INTERNAL SECRETIONS OF THE OVARY 



described remarkable experiments on Macaciis rhesus.. His 

 experimental results may be summarized as follows: 



(i) Ovariectomy before the next menstruation is due leads 

 to its premature appearance. The same effect is 

 produced by the experimental rupture of the large 

 follicles in the ovary. 



(2) The injection of the follicular hormone into the ovariec- 



tomized female results in the rapid appearance of the 

 local colouration found at certain stages of the cycle 

 in the female animal. 



(3) When the ovariectomized female has been regularly 



injected for some considerable period, the cessation of 

 injection is followed by the appearance of menstruation. 



The protocols, however, suggest that this last reaction is less re- 

 gular and less intense than is found in the normal female. 

 Allen explains these results by the assumption that the follicular 

 hormone is responsible for the pre-menstrual congestion of the 

 uterus, and that its secretion is carried on after ovulation by the 

 corpus luteum, and, in the event of pregnancy, by the placenta. 

 These assumptions would explain why menstruation in the 

 normal animal does not appear until some time after ovulation^ 

 and why it disappears entirely during pregnancy. If the pro- 

 duction of the follicular hormone is stopped prematurely, owing 

 to {a) atrophy of the corpus luteum and the failure of placental 

 tissue to appear, (b) experimental damage to large follicles^ or 

 double ovariectomy, (c) the cessation of injection in the ovariec- 

 tomized animal, uterine retrogression resulting in menstruation 

 sets in. Allen's explanation of his experimental results assumes 

 a continued activity of oestrin from the beginning of the follicular 

 phase to the end of pregnancy. 



The whole problem, however, is connected with the question 

 of the interpretation of the menstrual cycle of the Primates. 

 This has been considered in Chapter V, where it was concluded 

 that the phenomenon of menstruation is partly pseudo-pregnant 

 degeneration, and partly a prooestrous occurrence. It is pro- 

 bable, therefore, that the menstruation produced by Allen in 

 the injected monkeys was the prooestrous phenomenon, and it 

 seems possible to interpret all his experimental results on this 



