Chapter I · (continued 2)

The doctrines of the physiology of metabolism in men and beasts under different circumstances have exercised so powerful an influence over our comprehension of the relations of the individual during the sexual-life, that we practically find in all these teachings a powerful support, whence we may obtain many elucidations bearing upon the question lying before us, and may discover the principles necessary to complete our theory.

But, before entering upon the fundamental principles of the theory which I have set forth, I wish to mention a treatise of Mayrhofer’s, the principal results of which I shall briefly recapitulate. After that I shall mention briefly such information as I have met with respecting the nutrition of the mother.

Mayrhofer was led by critical notices and the observations of others, and, further, by his own experiences, to conclusions which he set forth in propositions, some of which I select here.

In the plants and the lower animals food plays a principal part in the development of sex. The sex is not generated, but depends upon external influences over the fruit which is in a state of development. And here we have a stage which precedes the separate sex in man, in which stage sexual neutrality must be regarded as normal, where also we find a kind of hermaphroditism.

Whether sex in the human species is determined at conception, or only develops itself afterwards, we must attempt to discover from obstetric experience.

The twins and triplets contained by one chorion are of the same sex, and have a common placenta in which the blood passages of both umbilical cords communicate with one another. On this account, also, many opine that the identity of sex is occasioned by the intermixture of the blood, an opinion regarded, on the contrary, by others, with incredulity, because the intermixture of the blood might very possibly lead merely to a mixture and not to homogeneity, under which circumstances dissimilarity of development would be possible enough. We may here adduce the following facts also (Jhering): The armadilloes produce a number of young in one litter, which are normally developed in a single chorion, and are of the same sex, as in the case with man when twins are developed in one chorion.

Heartless monstrosities (Acardiaci) are, in spite of imperfect nutrition (the conditions of proper nutrition by the blood are wanting in the embryo), of the same sex as normal offspring. Now, cases of this kind demonstrate that, in the later periods of development, although the conditions of nutrition are not alike, nevertheless the similarity of sex in the twins is maintained; so the foundation of the future sex would be laid at the period of conception. This rule which proves valid for the twins found in a single chorion, would apply for all human ova in general, because all possess the capacity of attaining their sexual character at conception.

According to Mayrhofer, placentæ are rare in which, where there are two chorions, communication is found between the vessels of the two umbilical cords. In addition to what has been already mentioned, Mayrhofer lays down the law, which we find frequently stated in many quarters, that the older of the two parents has a greater preponderance in favor of the propagation of his, or her, sex. Especially the physical maturity on the man’s side enables him to propagate his own sex, either in connection with younger or older women. A superiority on the part of the woman produces girls.

Our author only partly supports Thury’s theory, and considers it an open question whether the time of impregnation has any influence on the origin of sex. But he lays down this principle, that an economy of the semen by infrequent indulgence in intercourse is extremely favorable to the production of males.

It may be possible to obtain more exact data respecting the origin of sex from the artificial breeding of fish. In this case the properties of the sperm, as well as of the ova, might be observed at an earlier date by means of a fertilization effected externally. Attention might be also paid to the age of the parents. In short, all the factors of artificial influence upon the development of sex can in this case be taken in hand and controlled by varying the process of artificial fertilization. The author does not appear to know that the results obtained by artificial breeding differ remarkably from those which are the consequence of the natural multiplication of fish, nor that the development of sex is unfavorably affected in many ways. The cause of that lies very likely in the nutrition of the young fry, and perhaps, also, partly in cross-breeding.

What influence the physical welfare of the parents, and especially of the mother, has on the sex of the offspring in man, besides other factors deserving of attention, ought to be discoverable from the statistics of the lying-in hospitals. This is, in my opinion, hardly to be expected.

On various occasions, whilst taking into consideration the possibility of an influence on the part of the parents over the sex of the child (in such respects as have been placed before us in the literature dealing with this subject), we often had occasion to direct attention to the food of the parents. And especially the food of the mother seemed to us to be of the highest importance.

Now, it is universally known that metabolism is increased during pregnancy. The products of excretion in the case of pregnant women are much smaller than the quantity of matter taken in, in the shape of food. The difference, to a great extent, represents the matter taken to form the bodily substance of the embryo, in accordance with the anterior laws which have been fixed by the doctrines of the physiology of metabolism. It will, then, be necessary to pay particular attention to the investigation of metabolism. Suggestions are not wanting. They will be found amongst the observations of leading specialists. For example, Winckel observed that during pregnancy the temperature was slightly raised. This increase of temperature must practically be explained as due to the higher and more productive process of oxidization, which has to be accomplished by the human female for the sake of nourishing the fœtus.

During pregnancy the number of blood corpuscles suffers an observable diminution. Still plainer is the reduction of the quantity of hæmoglobin, when measured with Fleischl’s hæmatometer. This last phenomenon is very likely connected with a greater consumption of hæmoglobin, the substance being used up by oxidization.

Observations of setting hens are not without interest. In their case, also, a diminution of hæmoglobin is observable during the period of incubation. The hæmoglobin can sink to nearly 50 per cent. of the normal amount. With the increase of hæmoglobin in the embryo and its simultaneous diminution in the mother during incubation, it happens, at a certain period in the process of development, that the embryo in the egg and the setting hen possess a nearly equal measure of hæmoglobin with a nearly equal number of blood corpuscles. An increase of the quantity of hæmoglobin until the normal amount is reached may be observed in both towards the end of incubation.

The Rhine salmon each year go up in a well-nourished condition from the sea into the fresh-water streams to spawn. There they remain several months. They lose much of their muscular substance. (Miescher.) On the other hand, a great development of the sexual organs and of sexual secretions takes place, produced, probably, at the expense of the used-up muscular substance.

Many have paid particular attention to the nourishment of the maternal organism. Investigations have also been published dealing with the nutrition of the parent animals in cases when it was desired to exercise an influence over the sex.

In fact, we have frequently touched upon such subjects, although only lightly. Here, as we are about to proceed to the subjects of nutrition and metabolism in the human female awaiting impregnation, we find ourselves compelled to acquaint the reader with a number of facts which permit us to assume a connection between the food supply (including metabolism) and the development of sex.