Growth of the uterus from the moment of conception is one of the most interesting physiological studies. All its tissues, muscles, nerves, vessels, and lymphatics are increased in bulk and multiplied in number. The human ovum is an extremely minute microscopic cell, from one two-hundred-and-fortieth to one one-hundred-and-twentieth of an inch in diameter. This grows so rapidly that at the end of nine months we often have the average nine-pound baby. The growth of the muscular fibers of the womb is truly remarkable. They grow eleven times longer and twice to four times thicker, so that the growth of the womb keeps pace with that of the child. Changes immediately after confinement. Women as a rule, and their husbands also, are wofully ignorant of the condition of the womb just after confinement, and at this point it will be opportune to impart the necessary information illustrating that it is one of the most critical periods of the entire process, because the pelvic organs are again very sensitive, somewhat akin to the menstrual condition, namely, one of engorgement, or congestion. After the child is in the world, the uterus usually contracts to about the size of a cocoanut; its measurements and weight as compared with what it was before pregnancy have materially increased. The diameter is now about four inches, and its weight a little over two pounds. If we now stop to reflect that its weight was formerly an ounce to an ounce and a half, to which size and weight it must again return, we can readily appreciate the important changes that must take place to accomplish this object. The scientific world has only learned how this is effected within the last thirty years. It was a very important discovery. The superfluous or excessive tissues are converted into fat—the process is called _fatty degeneration_—and as fat the tissues are absorbed into the blood and disposed of, and thus gradually is the superabundant substance removed, until its measurements are as they were formerly and its weight as it was before. Involution is the name given to this process by medical writers. It signifies a rolling back of the size and substance of the womb to where it was before pregnancy. It is the physiological activity in the tissues of the organ to restore it to its former size and healthfulness. The time usually required for nature to accomplish this remodeling varies in different individuals from six weeks to three months. Subinvolution is a term employed to designate a partial or complete cessation of this restorative action. The prefix _sub_ means always _under_; in this case the same thing is meant, _under-involution_ or _incomplete_ involution.