In the female these consist of the womb or uterus, the ovaries, and a canal called the vagina which leads from the lower end of the uterus to an external opening, the vulva. The ovaries, two in number, are situated one on each side of the uterus. The uterus, which is pear-shaped, with the apex downwards, has three openings, one at the apex and one at each side at the upper part. These two upper openings are provided with a tubule extension, the Fallopian tubes, whose outer ends are fringed and lie in close relation to the ovaries. The ova or egg-cells are developed in the ovaries, and through a complex and elaborate process a single cell comes to maturity from time to time. It is then discharged into the open end of the Fallopian tube, reaches thereby the uterus, and if not fertilized is discharged through the lower opening of the uterus into the vagina. It is not known exactly when this discharge of ova takes place, but it is believed to coincide more or less with the monthly period. If, however, fertilization of the ovum takes place, it is not discharged, but remains in the uterus. The lining membrane of the uterus grows round and envelops it, and the wonderful process of cell division and multiplication proceeds which results in the growth and development of a child. These various organs are situated in the lower part of the abdomen, within the protection of the bony pelvis or basin. This pelvis is, compared with the male pelvis, broad and shallow, to provide for the passage of the fully developed child at birth. The vagina is the passage by which, during the birth process, the child reaches the outer world, and it is also the sex organ by which, in the female, the union of the male and female elements, of which we have spoken, takes place in the sex act. The male sex organs consist of the testicles, in which the sperm-cells or spermatozoa are evolved, of a coiled duct leading there from, and of the distinctive male sex organ, the penis. This last serves the double purpose of providing an exit for the contents of the bladder and for that emission of the spermatozoa which occurs in the sex act. There are also certain glands situated in close relation to this duct which provide a fluid which is emitted at the same time as the spermatozoa, the whole being termed the seminal fluid. It is thus clear that in both sexes there are essential reproductive organs, the ovaries in the one case, the testicles in the other, providing respectively ova and sperm-cells, and there are also organs for the purpose of securing the union of these two elements, namely the vagina in the female and the penis in the male. These two sets of organs form the primary sex characteristics or actual sex organs. _The Sex Act_