AFTER having discussed the anatomy of the sexual apparatus in full detail, we shall now proceed to demonstrate the physiologcal functions of the sexual life.
Here we shall deal from a more individual point of view with the further progress of the newly formed cells, i.e., the manner in which they are excreted from our body.(1)
We cannot, however, fully understand this secretory function until we study it in comparison with the other two secretory functions of the lower pole of the body, the intestinal function and even more the secretion of urine. Only thus can we fully appreciate the whole inter-relation; and difficult questions cobcerning one function may find a surprising solution by analogy with one of the other functions.
The close relationship between these three excretory processes has up to now been very little considered.
The connection between the three above-mentioned functions is obvious. Not only do the three organs lie close together, but they are supplied by related blood vessels, innervated by related nerve trunks and affected by the same external influences. Stimuli, drugs and poisons which affect one of these organs generally influence the other two to a greater or less extent in the same sense. The secretory character of the three organs is identical, and it is one and the same layer of muscle, the resistance of which has to be overcome by all three. Birds and fishes have only one orifice for the three secretions. Only mammals are more highly differentiated. Thus in man the male has two apertures, the female three.
The urinary secretion and the secretion of semen are indeed most closely related to each other. In the male they share a single common outlet, the prolongation of the urethra. Up to this point the embryonic excretory duct of a true embryonic kidney, the Wolffin body, serves as a genital canal. In the same way, the female genital canal is strictly speaking only the excretory system of a rudimentary pronephros.
I must at the outset ask the reader’s indulgence when discussing the intimate details of any one of the functions, which, if we employ the comparative method, are highly important on account of their analogy with the other functions, but in themselves are not very savoury
In the end this will be worth while, and if we pursue the comparative method the reader will have an additional gain. It is a touchstone for self-knowledge. Anyone who is annoyed by these physiological details, need not read any further; he must realise that he is scientifically not sufficiently emancipated to be able to study such difficult questions successfully. Let him choose something easier.
It was the duty of the author of this work not to withhold anything that could be of service to the reader. He begs that any obscurities or errors may be pointed out to him, so that he may avoid them in the future.
1 For the race the formation of the single cells is the main point. Individually, however, we are chiefly concerned with the secretory function. This is a physiological reason, in addition to the anatomical one, why testes and ovaries have always been considered as glands, whereas they are in reality tumorous, connected with an excretory duct system.