Chapter VII.

1. The seminal fluid in its emission is preceded by wind. The manner of its emission exhibits this; for nothing is expelled to a great distance without pneumatic force. If the seminal fluid is taken up by the uterus and retained there, it becomes inclosed in a membrane. For if it is expelled before it becomes articulated, it appears like an ovum inclosed in a membrane, but without any shell, and the membrane is full of veins. All animals, whether furnished with fins, feet, or wings, whether viviparous or oviparous, are produced in the same manner, except that the umbilicus in viviparous animals is turned towards the uterus, and in others to the ovum; and in some cases both ways, as in a certain kind of fish. Some of them are surrounded by a membrane, others by a chorion. First of all, the fœtus is contained within the last envelope. Then there is another membrane over this, which is in part united to the matrix and is partly separate, and contains water. Between these is a watery or sanguineous fluid, which in women is called prophorus.

2. All animals that have a navel increase by the navel; and in those which have acetabula the navel is united to the acetabulum; and in those which have a smooth uterus the navel is united to the uterus upon a vein. The position of all quadrupeds in the uterus is stretched out; that of fishes is on the side; bipeds, as birds, are folded together. The human fœtus lies folded up with its nose between its knees and its eyes upon them, and its ears turned outwards. All animals are alike in having the head placed upwards at first. As they grow, the head turns round, and the birth of all animals is naturally with the head forwards: for even in those that are folded together the presentation of the feet is unnatural. The embryo of quadrupeds contains excrementitious matter, as soon as it is matured, both fluid and solid. The latter is contained in the extreme parts of the intestine, the former in the bladder.

3. If animals have acetabula in the uterus, these acetabula always become smaller as the fœtus grows, and at last disappear. The umbilical cord is a covering for veins, of which the origin is in the uterus. In those creatures which have acetabula it originates in them; in those that have not acetabula it originates in the vein. In the larger animals, such as the fœtus of oxen, there are four veins; in smaller animals, two; in very small animals, as in birds, there is but one. Two veins reach the fœtus through the liver, from that part called the gates of the liver, towards the great vein; and two go to the aorta, where it is divided into two parts; and there are membranes round each pair of veins, and the umbilical cord surrounds these membranes like a covering. As the fœtus increases, these veins diminish. The embryo, as it grows, advances into the viscera, where its movements are manifest. Sometimes it remains rolled up near the pudendum.