64 THE PHYSIOLOGY OF REPRODUCTION 



certain other species of Macacus 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 haemorrhage has been recorded in 

 many monkeys and baboons, but there appears to be consider- 

 able 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 sinicus, 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 con- 

 stitution 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 inflammatory 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 inflammation 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 

 oestrus. 



The question as to the correspondence in time between the 



