Modern microscopical appliances have rendered it possible for us to observe the marvellous evolution of a complete and highly complicated organism from a single germ of undifferentiated protoplasm; and proof of the cell theory plainly shows us that the growth of the earliest embryo is precisely of the same nature as the growth of the child and youth.
It is of paramount importance for the reader to understand the significance of the sexual act, what the foetus is, and the main facts in its development. The subject of conception and foetal development is one which would overwhelm the average person were he left to consult the technical works on that subject; and yet the essential points of this advanced branch of anatomy may be chronologically presented in a way quite intelligible to the careful
reader.
It will well repay one to devote some considerable attention to the following pages bearing on the nature of our development; and while all may not be perfectly understood upon the first reading, and while the terms, derived from the Greek and Latin, may seem perplexing, yet the essential points will clearly appear. These facts every intelligent man should of course know.
Hermaphroditism. As pointed out heretofore, all sexual animals primitively show the characteristics of both genders by actually possessing the male and female genital
glands, which ultimately assume, normally, the special characters of one or the other sex.
A true hermaphrodite is an animal which has both an ovary and a testis, i.e., the male and female genital glands; and in it reproduction can take place without conjunction with another animal of its own species.
There are some true hermaphroditic animals; such is often the case among mollusks and worms. Thus the snail has an ovotestis which has the functions of an ovary and of a testicle, producing ova and spermatozoa; and several varieties of tape worms, which infest the alimentary tracts of man, the ox and the dog, are true hermaphrodites. Earthworms, though they copulate, are yet true hermaphrodites, each impregnating the other during the act of conjunction. Both the male and female germ glands exist in these animals; and other animals, again, are at one time female and at another male. Thus in some of the Turbellaria, or ciliated worms some of microscopic size, some several inches in length the individual first attains to maturity as a male, and later as a female, and during copulation among these animals, one is practically a male and the other a female, though later on the role may be reversed.
As anomalies among the vertebrate animals, including man, there are authentic instances of one individual having a testicle on one side and an ovary on the other, as well as the other imperfectly developed sexual characteristics of either sex. These monstrosities are however, spurious hermaphrodites, being in reality of one sex or the other, though imperfectly developed as to either.
The occasional union of the two sexes in the same human individual is only apparent, and so called human hermaphrodites exhibit the psycho sexual peculiarities of only one sex. Psychically and functionally there is no human hermaphroditism. For our procreation, accordingly, it is essential that there shall be a union, or "marriage", of the male and female elements of generation provided by two individuals of opposite sexes. The male element is called the spermatozoon, or spermatozoid, and the female element the ovum, or egg; the special function of the former being to fertilize, or impregnate, the latter, and from the conjunction of these male and female reproductive elements the embryo is conceived, succeeding generations of descendent cells being produced which ultimately bring it to full development.