The attachment of the fimbrix of the tube to the ovarium, which experiment has shown to occur during coition, esta blishes an uninterrupted canal from the uterus to the ovarium, and prevents the semen from becoming diffused in the abdomen.
The germ of the future being pre exists in the ovarium, where it is formed by a peculiar action of the part, in short, by a true secretion. This germ, in its original state, is a small vesicle of fluid, first noticed by De Graaf, whence the term of ovula Graafiana, applied to their appearance in the virgin ovary. Here we do not mean to countenance those doc trines of evolution which suppose, that generation only developes germs that have existed from the beginning of the world. We suppose, that the ova pro duced by the elaboration of blood, car ried to the ovaria by the spermatic ves sels, contain the rudiments of the new beings. But the germs in that state are inert, and require that the seminal spirit should be employed to rouse them from their inactivity. In birds and reptiles the formation of the germ by the female is incontestible ; it is not quite so obvious in the class of mammalia ; but we infer it here from analogy, and also from the ex periment of Mr. Hunter, in which the removal of one ovarium from a sow, di minished in a remarkable degree the number of young produced.
Fatal Existence. This is purely vegeta tive. The fcctu s receives the fluids brought by the vessels of the mother to the pla centa for its growth and nourishment. It may be considered as a new organ, the produce of conception, participating in the general life, but possessing a vitality peculiar to itself, and, to a certain de gree, independent of that of the mother. To say that it is asleep is erroneous ; for not only are the organs of sense and vo luntary motion in a state of perfect re pose, but also several of the assimilating functions are totally unemployed, as di gestion, respiration, and the generality of the secretions. The foetus, however, performs spontaneous motions, which ac coucheurs enumerate among the signs of pregnancy. It is nourished, like every other organ, by appropriating to itself whatever is found in the blood, brought by the vessels of the uterus proper for its purpose ; and the interception of this fluid by the ligature, or compression of the umbilical chord, occasions death, Suckling. The close sympathy between
the uterus and breasts is so obvious, as to attract the notice of every observer. Both these organs are developed at the same period of in, and cease together to performtheir functions, when the female becomes incapable of contributing to wards the continuation of the species. The breasts increase in size during preg nancy, but are never more swelled than after parturition. The infant applies its mouth to the nipple, and sucks ; i. e. forms a vacuum by inspiring, in conse quence of which the atmospheric pres sure forces the milk through the lacti ferous tubes into its mouth. The nipple experiences a vascular turgescence, or kind of erection ; which also affects the excretory tubes of the mammary gland, so as to cause them sometimes to expel the fluid to some distance by jets. The structure of the breast is explained un der the article MAMMARY GLAND, and the composition of their secretion under Ages, Temperaments, &c. Having thus gone through the animal economy, ac cording to its distribution into particular' functions, we shall just contemplate man in a general view, passing through the whole course of his existence, and note the principal epochal of his life, from its commencement to the tamination in death.
The first perceptible traces of the foetus occur about three months after concep tion. It is then animated by a very slight kind of vegetable life, and possesses true blood, and motion of the heart, about the fourth week. The latter, as observed in the chicken, has been named, from the time of Aristotle, punctum salient. The formation of the bones commences about the seventh or eighth week. The earthy particles are first deposited in nuclei in the clavicles, ribs, vertebrae, larger cylin drical hones of the extremities, lower jaw, and face : a very delicate network is also seen in some of the bones of the cranium.