In spite of many endeavors to elucidate this phenomenon, I was forced to have recourse to the symptoms alone, and to hope for the production of the male sex only from the disappearance of the sugar and the increase of the reducing substances. Certainly, further investigations showed that the same diet which was the most favorable to the production of the condition which I have named (the disappearance of the sugar from the urine and the simultaneous increase of the reducing substances), also effected the best albuminous increment in the body. Key’s statements teach us that male individuals put on more albumen than females, and that this is especially the case during the period of growth. Very likely the male embryo also requires a greater amount of albumen than the female, in the same way as this difference exists between the boy and girl.
We know as a universal rule that where there is rest there must be a balance of forces. If the ovum, the accumulator of the balanced forces in a state of rest, is to divide itself so as to produce in this way the future individual, some stimulant impulse, some energy is absolutely necessary to disturb the balance of forces, and to induce the development of the cells. This impulse may be such a one as occasions destruction. But it may also be one that gives occasion to new growth, to tissue formation. (W. Haacke.) We must describe this impulse as functional, and recognize in it a peculiarity which belongs to the organic world alone, the vegetable and animal kingdom. Every movement, every use of an organ, may serve as a stimulant impulse, and contribute to its development. Thus we find, in the case of great thinkers and poets, of celebrated generals, etc., a powerfully developed brain. Oarsmen, gymnasts, and swimmers have far stronger muscles than men who follow less fatiguing callings. In all these cases there are impulses leading to increased growth of the organs. In the growth of the fertilized ovum we have to deal again with a phenomenon of impulse, a part of which is the property of the ovum itself, a part, however, also dependent upon external influences. We call the former autoplastic, the latter xenoplastic impulse. (Haacke.) It is easy to understand that a purely autoplastic development (eine reine Autoplasie, a pure autoplasia) cannot exist. Out of an ovum alone, without the agency of new impulses, without the taking up of new matter, no new individual could develop.
The stomach furnishes the gastric juice. It is stimulated to do so by the food. The food is digested, undergoes absorption in the intestine, and becomes lymph. Blood is formed. The blood passes through the several organs and tissues, nourishes them, and replaces the substances used up by work. As soon, therefore, as the stomach and intestine, with the intestinal glands, fail in their functions, all the organs, which stand in physical relation with them, suffer; because they are constantly during their work consuming matter, and are now receiving no fresh supplies. The case of the other juices of the body is the same. The thyroid glands supply the body with a principle without which a person cannot be in a normal condition. Similarly the testicles, as glands, supply the body with a principle the want of which gives a man distinctly female qualities, as we perceive in the case of eunuchs.
There is no doubt that the males and females of a race of animals develop out of the same germinal-matter. Its development depends upon two important factors, the impulse, and the capacity to take up matter conditioned thereby. By taking up matter the substance of the newly developed cells is increased, and this in turn prompts them to repeated division, until at last an organ is developed. The new organ again furnishes new impulses, and so influences the development of other organs. The impulses are of themselves physical and chemical. (Haacke.) In the ovule and the embryo the impulses are what chiefly bring about new growth. These impulses the ovum receives from the mother whose product it is. Now, as of the most different impulses now one and now another comes to the front, the embryo will acquire at this time rather these qualities, and at that time those. The impulse will occasion now a greater addition of matter to this organ, and now a greater addition of matter to that. According to observations made up to the present time, there is hardly any doubt that the development of the organs of sex requires an impulse as does the development of all the other organs. These sex-determining impulses originate, like the other development-determining influences, from the mother, since it is she that supplies to the embryo, as agencies of impulse, the juices derived from the food which she has taken. In addition to these, the embryo receives also from the mother such products as are required for the growth that follows the impulse. If the mother gives the child no material for growth and no impulse, then the child, since it is dependent upon the mother, must perish. Now, according as a developing ovum or an embryo either receives the juice, the means of impulse, for the acquisition of the male sex, or for the acquisition of the female sex, so will a male or a female result.
Of what kind the means of impulse are, the juices are, which occasion this I do not know. I can only supply the conditions requisite for them; I can see only whether they are present. And so I again come back to this, that we may expect a male individual from the ovum when the juices are developed which serve as a functional means of impulse for the male sex. These juices can come into existence in the organism under the most different circumstances. But they certainly do come into existence, if we can so feed the mother that we cannot find in her urine even the faintest trace of sugar, but instead of it an increased excretion of reducing substances, accompanied by a relatively high exchange of nitrogenous substances. These facts can, therefore, serve us only as a symptom of processes taking place in the organism. In consequence our task will be to follow up in the various cases the conditions of this symptom, in order that we may try so to feed the mother individual that she may attain to giving the effective impulse; and this we have certainly accomplished by the increased excretion of the reducing substances and the disappearance of the normal urine-sugar.