THE " SKXUAL RRASON " OF MAMMALS. 63 



to refuse the male, whereas in the human female sexual 

 desire is not confined to the time of menstruation. 



5. ''Heat" is necessary to the production of the species in 

 tlie lower animals, while in woman "desire" is said to be 

 not essential to conception. 



6. In the lower animals the ovaries are said to contain 

 ripe ova only during the time of ''heat," whereas ripe ova 

 are said to be found in the human ovary at all times with- 

 out reference to menstruation. 



7. There is said to be no proof of the identity of the two 

 conditions. 



T think these propositions fairly cover the ground over 

 which those who deny the relationship of what they call 

 "heat" to menstruation have hitherto travelled. 



It will be seen at a glance that the denials originate, in 

 most instances, in misconception of the facts, and that many 

 of the errors are due to the misuse of terms. 



It will be worth while, however, to answer each of them 

 separately, and the following replies are numbered to corre- 

 spond with the numbers of the above objections. 



1. The discharge in many animals during the pro-cestrura 

 contains blood and sometimes uterine tissue ; it is not always 

 solely mucus, and when blood is absent it has been shown 

 that its absence is due to a modification of, and not to any 

 radical difference in, the process. 



2. The term "heat" is here wrongly used; it is made to 

 include both the pro-oestrum and the oestrus in the lower mam- 

 mals, and is compared in that extended sense with the term 

 menstruation, which is an error. The time the lower animals 

 will permit of coition is not during pro-oestrum, which is 

 synonymous with menstruation, but during oestrus, which 

 immediately follows the pro-oestrum. I have shown above 

 that there is not wanting evidence that the same may be true 

 for the human female. 



3. Although the time for sexual intercourse among human 

 beings is not universally confined to particular seasons, I 

 have shown that in some cases this is so, and that in all 



