THE UMBILICAL CORD.
The foetal blood is transmitted to and fro between the body of the child and the placenta, by a cord which contains two arteries and one vein. This is called the umbilical cord, because it enters the body at the middle of the abdominal region, or umbilicus. It is composed, also, of its own proper membranous sheath, or skin, and cellular tissues, besides the blood-vessels. Two months after pregnancy, this cord can be seen, when it commences to grow rapidly.