The 'sexual season' of mammals and the relation of the 'pro-oestrum' to menstruation / by Walter Heape.

  • Walter Heape
Date:
[1900]
Catalogue details

Licence: In copyright

Credit: The 'sexual season' of mammals and the relation of the 'pro-oestrum' to menstruation / by Walter Heape. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    In those animals which experience the dioestrous cycle the sexual season (when conception does not take place) consists of a series of such cycles, two or more; and may occupy any length of time from one month to the whole year. In the former case it is limited to a definite portion of the year only, while in the latter case it may be coincident with the whole reproductive period [human female, under certain conditions]. But when the recurrence of the dicestrous cycle is limited to a definite portion of the year, the sexual season is, of course, also limited to that period, and there is consequently a period of rest, which is the anoestrum. In such cases the non-pregnant female experiences a series of dioestrous cycles during the sexual season, at the end of which, instead of dioestrum following metcesti’ura, the latter is succeeded by anoestrum, which persists until the next sexual season occurs. In order to distinguish between the two classes of female mammals into which the occurrence or absence of dioestrum divides them, I have called those which experience a single oestrus during each sexual season, or in other words those in which the anoestrous cycle only occurs, moncestrous mammals; while those whose sexual season is occupied by a series of dioestrous cycles, or in other words those who experience a series of recurrent cestri, I have called poly- cestrous mammals. The complication into which an otherwise simple story is thrown is due, therefore, to variation in the quiescent period. In some animals this may be a very brief period, never lasting- more than a few days; in others it may occupy from two to eleven months each time it occurs ; while in others again both these conditions are experienced at different times of the year. Functionally, no doubt, these two varieties of the quiescent period are homologous, the one is a modification of the other; and the modification is probably due, as will be shown below, to an increased or decreased power of reproduction. At the same time, for the purposes of the pi-esent paper, the difference between them is essential, and their relation to the sexual
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