THE "sexual season" OF MAMMALS. 55 



and the excitement there is subsiding, it would seem as if 

 the external organs gain renewed stimulus, and it is then 

 that CBstrus takes place. If the uterine changes are confined 

 to Stages II and III, that is simply hypertrophy and conges- 

 tion of the mucosa, CBstrus rapidly follows the first external 

 signs of pro-cestrum ; but if more elaborate disturbance takes 

 place in the uterus, the period of oestrus is delayed. 



Thus it is during the subsidence of the uteinne disturbance 

 that oestrus takes place. The period during which the dis- 

 charge continues is not, however, a true indication of the 

 permanence of the uterine disturbance. In comparatively 

 large uteri, especially in those which extend as long horns 

 from the corpus uteri, the area of denudation or haemorrhage 

 may be situated far from the vagina ; and the products of 

 that liEemorrhage and of denudation may take a considerable 

 time to find their way to the exterior ; this is especially the 

 case where there is little blood and much mucous dischai'ge. 



We have seen above that in the monkey. Stage VIII, a 

 new epithelium is formed over the surface of the newly 

 denuded uterus before the blood-clot is evacuated ; and in 

 the same way, before the discharge from long-horned uteri 

 reaches the exterior, the uterine disturbance is largely 

 allayed, and renewed stimulus may be supplied to the ex- 

 ternal generative organs. 



In all animals which have been investigated, coition is not 

 allowed by the female until some time after the swelling and 

 congestion of the vulva and surrounding tissue is first 

 demonstrated, and in those animals which suffer from a 

 considerable discharge of blood, the main portion of that 

 discharge, if not the whole of it, will be evacuated before 

 sexual intercourse is allowed. 



Thus in Pachyaromys duprasi, which experiences 

 hemorrhage, coition is not allowed during the flow (Lataste, 

 1887). 



Bitches, except rarely, receive the dog only after bleeding 

 is over (Stonehenge, 1887), although a mucous discharge, 

 which frequently continues after the discharge of blood 



