The _waters_, enclosed within the Amnion, (see Plate XII,) have now increased to their greatest quantity; and there is also, in most cases, a second body of fluid between the Amnion and the Chorion, which coming away before the real discharge, is called the _false waters_.--(See Plate XII.) The quantity of the true waters, at birth, is about twenty, or from that to thirty ounces, but is very variable. It is of a greenish color, rather muddy, and heavier than water. It contains albumen, (white of egg,) sulphate of soda, and lime. Ninety-eight per cent. of it however, is pure water. It appears to be excreted, like perspiration, from the surface of the membranes, and most likely is merely the watery portion of the blood exuded through. The uses of this fluid are various. As already stated, it probably supplies some nutriment to the fœtus, which it also protects, in a great measure, from pressure and from concussions. It also prevents the limbs from adhering, and helps to distend the mouth of the Womb, in the earlier stages of labor, besides affording an abundant slippery fluid for the purpose of lubricating the passages, thus making the passage of the child more easy.--(See Plate XII.) The other two membranes, the Chorion and Decidua, are not of much importance in our present explanation; and practically, in fact, the whole three may be regarded as _one envelope_, surrounding the child and the waters in which it floats. THE PLACENTA. At the full term the Placenta, (See Plate XII,) is about six or seven inches in diameter, and nearly circular, though often irregular. Its thickness varies from one to two inches, and is greatest where the cord is inserted. Sometimes it is very large, or very thick, and may then be difficult to extract, and even cause serious accidents. As already explained the Placenta is composed of a mass of blood-vessels, by means of which the blood of the fœtus is, in some way, brought into contact, or commingled with that of the mother. Its uterine face is irregular, being broken into lobes, or cotyledons, on which may be seen a vast number of little veins and arteries, corresponding with others on the inner surface of the Womb. Its outer surface is of a grey red color, and covered with the fœtal membranes, under which the large blood-vessels can be traced. The Placenta is usually attached to one side of the Uterus, near the fundus, or at the fundus, but sometimes it grows wholly, or in part, over the mouth of the Womb; an occurrence which may cause serious consequences.