The function of generation is dependent upon the combined action ot two sets of organs, in each of which a peculiar product originates, qualified for union with the other so as to produce a new individual.

Throughout nature this primary principle exists; the essential characters of the organs of generation in the different classes of organized beings are universal. A study of botany discloses the fundamental law, modified in the different varieties. In the lily, violet, etc., the male and female organs both exist upon one stalk. In some cases, separate male and female flowers are found on the same plant; in others, as in the willow, poplar and hemp, they are situated on different growths, which otherwise resemble each other.

In animals the essential parts of the female generative system are called the ovaries. In them is produced the germ or egg, which is capable of being developed into a young animal, when fecundated or made fruitful by a substance which is produced in the testes of the male.

In some of the lower animals both sets of generative organs exist in the same individual. In them the ovaries are first matured and perform their functions, after which the male organs become active. Thus they are literally first female and afterwards male, exercising their appropriate actions at different ages.

In all the higher classes of animals the two sets of generative organs are situated in separate individuals, dividing the species into two sexes, the male and female, each having accessory organs which give rise to a greater dissimilarity in their anatomy.

The product of the ovaries, or egg, is a globular body, which in quadra*peds measures about one, one hundred and twentieth of an inch in diameter. These eggs exist primarily in the organs of an animal as a part of their natural organization. Their essential constituents are of the same peculiar qualities, and the process of development follows the same general laws in all nature. In the lower animals, as the generative season draws near, a certain number of eggs, which were previously but partially formed and inactive, grow larger and undergo structural changes. They ripen, as it were, distending the follicles, and finally, when fully matured, the inclosing walls are ruptured and they are discharged into the oviducts. When simply expelled from the ovary and conveyed through the oviducts towards the external genitals, the matured egg soon loses its vitality and becomes decomposed. It is not of itself capable of being developed into the embryo, and is only rendered fruitful by the germ of the opposite sex. When the seminal fluid of the male is introduced into the female generative passages by sexual congress and meets the egg at or near its discharge from the ovary, it causes its retention, stimulates it to continued development, and renders it capable of a more complete organization.