The one prominent function of the generative system is the perpetuation of the race, and using the term in its widest sense, generation includes all the processes which result in the multiplication of living beings.

Reference to the description of the organs which constitute the generative system in the higher animals - the mammals, for example - will show that two sets of complicated structure belonging to two sexes - male and female - are concerned in the function, and a knowledge of the functions of the two distinct sets of organs will leave no room for doubt that the female has the largest share in the perpetuation of the species. " Omne vivum ex ovo" is a very familiar quotation, but it contains a most important truth. The ovum of the female animal or plant contains all the material necessary for the formation of a new animal or plant. In the ovum or egg there is a germ possessing a dormant vitality, which only awaits contact with the sperm-cell of the male to become actively alive and capable of appropriating the material by which it is surrounded, and evolving from inert and shapeless substances all the tissues and organs which constitute the new existence.

With the impregnation of the germ-cell by the action of the male, the more complicated function of the female begins, and must go on until the new creature is sufficiently advanced to live an independent existence. A merely superficial analysis of the function thus lightly sketched, reveals the three essentials of which it consists, namely, impregnation, gestation, and parturition, each of which includes certain conditions which vary in different beings.