56 OBSTETRICAL PHYSIOLOGY. 



more particularly brought about changes in this respect, and by inducing 

 a more rapid development of the organism, has hastened the advent of 

 this period. And it may be said that puberty is sooner attained in the 

 female than the male, and that domesticity has also considerably modified 

 the periodicity of the procreative manifestations in the former ; though in 

 the latter it may also be affirmed that this periodicity is not so marked, 

 the generative functions being always more or less in activity. 



The aptitude to procreate, though generally admitted as an indication 

 of adult age, yet appears before animals have attained their full physical 

 development, and is present in some creatures at a comparatively early 

 period of life, depending upon climate, food, and other circumstances ; 

 the Pig may conceive when only four or five months old, or earlier ; the 

 Sheep and Goat at eight to twelve months ; the Bitch at seven to ten 

 months ; the Cat at from eight months to a year, though it is usually in 

 " heat " for about ten days before it is a year old ; the Cow at twelve to 

 eighteen months ; and the Mare at from twelve months to two years. 



Saint-Cyr has seen Mares which foaled when thirty months old ; and 

 others which, going at large, have received the Horse before the end of 

 their first year, and foaled at twenty-two months. Heifers have also taken 

 the Bull at five, six, sev^en, and nine months, and calved at fourteen, fif- 

 teen, sixteen, and eighteen months. In the first volume of the Lancet 

 (1835-36), there is mention made of a Bull calf less than three months 

 old, which copulated with a Quey calf about two months old, and within 

 nine months the latter brought forth a calf. Quey and calf did well. 



With regard to the period when procreation ceases in animals, I cannot 

 discover any reliable data to arrive at a trustworthy conclusion. The 

 Mare has not ceased to breed after thirty years of age, and the Cow and 

 Sheep have bred beyond twenty years. I have notes of Mares producing 

 foals at twenty-eight, thirty-two, and thirty-eight years of age. 



The changes incidental to the procreative period of life in the female 

 are chiefly centred in the ovaries and uterus : organs destined to play a 

 pre-eminent part in the perpetuation of the species, and whose functions 

 are inter-dependent. The ovary is doubtless the principal and essential 

 agent in generation ; as it gives the necessary and effective stimulus to 

 the condition termed rutti7ig ox heat, and furnishes the germ which has 

 been, or is intended to be, fecundated ; while the uterus secretes mucus 

 and the peculiar fluid ejected at that period, receives the ovum, forms the 

 decidual temporary or enveloping membranes in some cases, nourishes 

 the foetus, and finally expels it. So that the ovaries and uterus co-operate 

 in the accomplishment of the four chief functions of the uterine system : 

 cestrum, conception, gestation, and parturition. These we will consider in 

 the order in which they stand, describing the phenomena which charac- 

 terize or accompany them, and noting the conditions upon which their 

 evolution mainly depends. 



SECTION II. CESTRUM OR MENSTRUATION. 



The rutting, heat, oestrum, or veyiereal oestrum of animals is analogous to 

 " menstruation " in woman, and marks the period of maturation in the 

 ovarian ova or ovum, according to species. This condition is intermittent 

 or periodic, not continuous ; and is characterized by a peculiar systemic 

 excitement that usually continues for a somewhat definite period in the 

 two sexes. In the male and female, but especially the latter, the genera- 



