THE LIFE-HISTORY OF THE OVUM. The physiology of the remaining sexual organs of the woman may perhaps best be studied by considering the story of the Life-History of the Ovum, or human egg, for the functions of such organs are concerned with such life-history of the egg, and really exist merely to create such a history, or rather, to produce the process which constitutes the basis of such history. The ovum, or egg, when discharged from the ovary, is at first surrounded by a few cells which serve as nourishment, but which soon disappear. It enters the Fallopian Tube and begins its journey toward the Uterus, being urged on its way by the constant movement of the lining-cells of the interior of the tube, in the direction of the Uterus. Certain changes in structure occur. Its passage to the Uterus may be interrupted, and the ovum lost and finally cast off. But the ovum that is successful finally arrives at the Uterus where it awaits impregnation or fertilization by the spermatozoon of the male. If copulation occurs within a reasonable time after the arrival of the ovum, it is impregnated or fertilized. Fecundation results and conception ensues, the ovum then remaining attached to the walls of the Uterus, and in time develops into the foetus. If, however, the ovum is not impregnated, because of absence of copulation or from other causes, it gradually loses its vitality, and is finally cast off with the several uterine secretions. It should be explained here that the "spermatozoon" of the male (the plural of the term is "spermatozoa") is the male generative "seed." The sperum, semen, or seminal fluid of the male is filled with hundreds of thousands of spermatozoa. Each spermatozoon is a minute living, moving creature, resembling a microscopic tadpole. It has a head, a rod-like body, and a thin hair-like tail, the latter being kept in constant motion from side to side, by means of which the tiny creature is enabled to travel rapidly from one point to another. The human spermatozoon measures about one six-hundredth of an inch in length. It is composed of protoplasm, the substance of which all living creatures are composed. The spermatozoa are believed to be developed from a parent sperm-cell, by the process of segmentation or subdivision, which process is common to all cell-life. The numerous spermatozoa dwell in a gelatinous substance, which, mingling with the other fluidic secretions of the glands of the male, constitutes the male seminal fluid, sperm, or semen, which is ejaculated by the male during the process of copulation.