Page:The Works of William Harvey (part 1 of 2).djvu/622

522 fold up their limbs in such a way as to form an oval or globular figure: so in like manner embryos, passing as they do the greater part of their time in sleep, dispose their limbs in the position in which they are formed, as being most natural and best adapted for their state of rest. So too the infant in utero is generally found disposed after this manner: the knees are drawn up towards the abdomen, the legs flexed, the feet crossed, and the hands directed to the head, one of them usually resting on the temples or ears, the other on the chin, in which situation white spots are discernible on the skin as the result of friction; the spine, moreover, is curved into a circle, and the neck being bowed, the head falls upon the knees. In such a position is the embryo usually found, as that which we naturally take in sleep; the head being situated superiorly, and the face usually turned towards the back of the mother. A short time, however, before birth the head is bent downwards towards the orifice of the uterus, and the fœtus, as it were, in search of an outlet, dives to the bottom. Thus Aristotle: "All animals naturally come forth with the head foremost; but cross and foot presentations are unnatural." This, however, does not hold universally; but as the position in utero varies, so too does the mode of exit; this may be observed in the case of dogs, swine, and other multiparous animals. The human fœtus even has not always the same position; and this is well known to pregnant women, who feel its movements in very different parts of the uterus, sometimes in the upper part, sometimes in the lower, or on either side.

In like manner the uterus, when the term of gestation is completed, descends lower (in the pelvis), the whole organ becomes softer, and its orifice patent. The "waters" also, as they are vulgarly called, "gather;" that is, a portion of the chorion, in which the watery matter is contained, gets in front of the fœtus, and falls from the uterus into the vagina; at the same time the neighbouring parts become relaxed and dilatable; in addition to which the cartilaginous attachments of the pelvic bones so lose their rigidity that the bones themselves yield readily to the passage of the fœtus, and thus greatly in-