They have the remarkable property of moving about with considerable activity, and their number is almost beyond computation.
Only One Male Element Necessary.—Although this number is so vast, yet only a single one is required to endow the female cell, or egg, with life. It is another illustration of how nature does everything possible to increase the chances of perpetuating the race, for without such immense numbers, the chances of the female egg being fertilized would be much less.
May Live for Days.—Although these male elements can live but a few hours outside of the body, even when especial precautions are taken to make every thing favorable to their existence, yet they have been known to maintain their full life in the vaginal canal for more than eight days after their discharge; another remarkable provision of nature, for the prolonged existence of these cells increases the probability of the fertilization of an egg, and thus increases the chances of producing a new life.
The Female Element.—As I have already said, the female germ-cell is also known as the ovum, or egg. A single ovum is shown in [Fig. 1].
If not fertilized by the male elements, the egg passes off into the outside world; if fertilized, it stops in the cavity of the uterus, where it forms an attachment. Here it remains until perfectly developed, when, at the end of nine months, it is brought forth to the outside world as a perfect infant.
One Female Element; Many Male Elements.—The human ovum is often said to be a miniature of the egg of the common fowl, although there are some quite marked differences between the two. It is a very interesting fact to note that there is only one egg given off at a time; while there are many thousands of the male elements. This is in harmony with the larger size of the egg, and the fact that while this egg awaits fertilization it is most carefully protected within the body of the mother.
Where is Life First Made?—Where the wonderful union of the male and female elements takes place is not definitely known, although it is generally believed that it is upon the surface of the ovary, itself.
If this be true, then it is necessary for the male element to traverse the whole length of the uterine cavity, out along the course of the Fallopian tube, and there be deposited on the surface of the ovary.
The Fertilized Egg.—When a fertilized or impregnated egg is set free from the surface of the ovary, it follows the same course that the unimpregnated egg does until it reaches the uterus. Here some most remarkable changes immediately take place whereby the egg is held firmly to the inner wall of the uterine cavity; while the unimpregnated egg, as I have said, passes down the uterine cavity into the vagina, and thus out of the body. In other words, the fertilized egg is retained within the body, while the unfertilized one is cast off.
One Egg Discharged Each Month.—An ovum, or egg, is discharged during each menstrual period. It cannot be seen because of its minute size, a magnifying glass being necessary to detect it, even under favorable conditions. At just what time during this period the ovum is cast from the body is not definitely known, but it is generally thought to be toward the latter part.