58 THE PHYSIOLOGY OF REPRODUCTION 



anal orifices. Such a swelling was noticed in various species of 

 Cercocebus and Papi,o, and in Macacus nemestrinus^ but not in 

 Cercopitkecus, or in certain other species of M<IC<-H* including M. 

 rhesus. Heape, however, states that in menstruating specimens of 

 M. rhesus observed by him, and M. cynomolgus, the skin of the 

 buttocks became swollen and red or purple in colour, as well as the 

 skin of the abdomen,, the inside of the thighs, and the under surface 

 of the tail, while the skin of the face tended to become flushed or 

 blotched with red; at the same time the*nipples and vulva were 

 congested. Menstrual ha-morrhage has been recorded in many 

 monkeys and baboons, but there appears to be considerable variability 

 in its extent. Pocock says : " In baboons it may or may not take 

 place, and may be great or little in amount. It has been noticed to 

 occur in some profusion in a female of Macacus sinicm, and not to 

 occur appreciably in a female of the closely allied species, M. 

 fascicularis. Obviously, therefore, it cannot be associated with the 

 inflammatory swelling of the genito-anal region [since no swelling 

 was apparent in either of these two species] ; and it is hardly likely 

 to have a specific value in taxonomy. Perhaps the nearest guess 

 that can at present be made is the surmise that it is dependent on 

 the constitution or health of the individual." 



Heape noticed that in M. rhesus the menstrual discharge lasted 

 for from three to five days. Pocock records that in a Chacma 

 baboon ( Papio porcarius) haemorrhage continued for about four days. 

 In both animals the phenomenon was truly "menstrual" (i.e. of 

 monthly occurrence). 



Pocock records the interesting fact that whereas the swelling of 

 the congested area commences at about the same time as the 

 haemorrhage, it does not reach its full size until several days after 

 the discharge is over. It soon afterwards begins to shrink, and in 

 about another two weeks has disappeared, so that the female at a 

 distance is indistinguishable from the male. After a few days' rest 

 congestion again sets in, and the process is repeated. Pocock 

 suggests that this sub-caudal swelling may serve the purpose of 

 apprising the male (at a distance) as to when the female is "on 

 heat," and it is to be noted that it is at its maximum after 

 menstruation is over (as just mentioned), and so presumably 

 therefore during a definite period of osstrus. 



The question as to the correspondence in time between the 

 processes of menstruation and ovulation is discussed in a later 

 chapter. 



1 Similar observations had been previously described in Cercopithecm, Papio, 

 and other species by certain of the older naturalists. See St. Hilaire and 

 Cuvier, Hist. Nat. des Mammiferes, 1819-35. 



