42 WALTER HEAPK. 



In monkeys the oestrus has not usually been carefully 

 noticed, but I am assured that the Moor macac in confinement 

 (Zoo.) has a definite oestrus which lasts two or three days ; 

 and in a few other monkeys a similar condition has been from 

 time to time noticed (Ellis). 



In the human female there is not wanting evidence of a 

 similar condition (Aristotle; Martin, 1888; Haycraft, 1880), 

 and on this point information has been supplied to me by 

 various experts, which leads me to think it will probably be 

 found that those women who are most robust, and who suffer 

 least from the enervating effects of civilised life, experience 

 a condition comparable to that of oestrus in the lower mam- 

 mals (confer also Ellis). 



The Effect of Maternal Influences on the Sexual 

 Season and on Oestrus. 



Maternal influences may or may not completely disorganise 

 the sexual season ; this depends upon whether or not they 

 interfere with its recurrence or with that of oestrus. 



Gestation. — (testation may or may not interfere with the 

 recurrence of one or other of these factors. In the dog it does 

 not do so, because the dog has only one oestrus during each 

 sexual season, and the period between two sexual seasons, 

 i. e. the ancestrum, is longer than the period of gestation. 

 In the elephant it does do so, because the gestation period is 

 longer than the anoestrous period. So also with badgers 

 this appears probable (Denwood, 1894). In camels, whose 

 gestation occupies thirteen months, the sexual season is inter- 

 fered with by gestation, and is on that account put off for 

 another year. The camel conceives every two years (Swayne, 

 1895). In the rat, on the other hand, gestation does not 

 interfere with the recurrence of the sexual season, but does 

 interfere with that of oestrus, because the rat has a series of 

 dioestrous cycles in each sexual season, and she may also 

 undergo a series of gestation periods during that time, and 

 because the maternal generative cycle (twenty-one days) is 

 longer than the dioestrous cycle (ten days). 



