Part 64

Maritegoute’s breeding experiments at the sheep-farm of Blanc (Haut-Garonne), on the other hand, gave divergent results. In the early part of the pairing season, as long as the ram’s sexual powers were completely unimpaired, he procreated more male than female lambs. But when a few days later a great number of the ewes were simultaneously on heat and the ram, owing to very frequent acts of intercourse, began to be sexually exhausted, the procreation of female lambs was in excess. But when, finally, this period of maximum demands upon the ram’s powers was past, and the number of ewes on heat became once more small, the procreation of male lambs in preference to female was again observed.

The data obtained by Düsing from the Prussian stud-farms, in which, when greater sexual demands were made on the stallions, more males were procreated, have been already mentioned.

Fiquet made interesting experiments on cows and believed that in this way he was able to demonstrate the influence of nutrition upon the determination of sex—to such a degree, indeed, that he believed it was possible to breed calves of either sex at will. The following method gave him positive results in more than thirty instances. He never had the cow served by the bull at the first heat, but only at the second (if a cow is left unserved when on heat, the heat recurs after an interval of three weeks). The interval of three weeks was utilized in the preparation of cow and bull for the copulatory act. If a bull-calf was wanted the cow was supplied with the most invigorating fodder and was kept on the richest pasture available. The bull, on the other hand, that was to serve this cow was turned out to graze on the poorest pasture and was given poor fodder. At the end of the three weeks, when the cow came on heat for the second time, its sexual appetite was as intense as possible, whereas the bull showed but slight inclination to the sexual act. If the bull now served the cow a bull-calf was procreated. The opposite procedure led to the procreation of a heifer. For this purpose Fiquet kept the cow on low diet during the interval between the first and second heats, and had her first served by a castrated animal. When in this way, and by the low diet, the sexual appetite of the cow had been sufficiently diminished, it was served by a lusty bull, which for a long time had not been put to any cow, and the sexual potency of which had been increased to the uttermost by feeding it for several weeks on the most invigorating fodder.

The results of these experiments, according to which the nutrition of the parent-animals before the copulatory act has an influence upon the determination of sex, is explained by Düsing in this way, that nutrition influences also the quality of the reproductive products. “Poor nutrition gives rise to diminished functional capacity of the genital apparatus. Thus, for example, the production of semen is lessened. It can, in fact, hardly be replaced as quickly as it is used up. This occurs when there is a lack of adequate means of subsistence, and also when there is a lack of comparatively young males. In both cases alike we trace the effects in the birth of an excess of males. Converse conditions give rise to an excess of female offspring.”

Passing now to consider investigations made by physiologists, Born, at the anatomical institute at Breslau, has endeavoured to solve the problem of the determination of sex by means of experiment. He employed for this purpose rana fusca, an animal with which positive results can be obtained in a comparatively short period of time. He examined the sex both of the frogs in the free state (165), and also of larvæ which he had bred in specially arranged aquaria. Whereas among the frogs developing in the open, the numbers of the sexes appeared to be approximately equal (there was an excess of females amounting to 2 or 3 per cent.); among those bred in the aquaria there was an enormous preponderance of females (96 per cent.). This remarkable result is referred by Born to the inadequate supply of nutriment in the case of the larvæ bred by him (he fed them on hydræ and on putrefying frog and tadpole meat); from an examination of the alimentary canal of tadpoles caught in the open Born ascertained that their normal food was the mud of the pools in which they were hatched, containing infusoria, radiolariæ, diatoms, algæ, etc. The accuracy of this explanation appeared to Born to be more convincingly shown by the results in the case of one of his twenty-one aquaria. In this one alone the percentage of males was as high as 28 per cent., and the tadpoles in this attained the same size as those developed under natural conditions in the open, whilst in all the other aquaria the tadpoles remained abnormally small. This particular aquarium, owing to an oversight, had pond-mud on its floor, whilst all the other aquaria were floored with clean sand.

A. von Griesheim disputes Born’s results and believes that the latter, determining the sex of the tadpoles by means of a hand lens, must have mistaken a great many female tadpoles for males. He himself, by repeated enumerations of a large number of tadpoles (685), part caught in the open and part taken from a large aquarium, found that the ratio between the sexes in the case of rana fusca was regularly 36.7 males to 63.3 per cent. females.

E. Pflüger refers the divergence between Born’s results and his own and those of von Griesheim not to any error made by Born in the diagnosis of the sex of the tadpoles, but to the fact that in the latter’s aquaria the mortality of the male tadpoles was probably greater than that of the females. Pflüger endeavoured to ascertain whether the concentration of the semen might have an influence in the determination of sex. A quantity of frog-spawn was fertilized with concentrated semen, taken direct from the seminal vesicles, and another quantity of spawn was fertilized with diluted semen, obtained by making an aqueous extract of the incised testicles. The ratio between the sexes in the case of the two lots of tadpoles, which were kept in separate aquaria, proved, however, to be mathematically identical. But another experiment showed that the number of males was very different, according to the kind or race from which the animals were derived. He therefore believes that for the character of the development of the reproductive organs, the race of the parent animals is determinative. There is very little likelihood of being able to modify this inherited sexual ratio by means of outward influences affecting the ova and the ripe semen prior to fertilization, and just as little by means of a number of abnormal influences (change of climate, of water, of nutriment, etc.) acting on the fertilized ova.

Düsing,—who in his work on “The Regulation of the Sexual Ratio” (Jena, 1884) most ingeniously advocates the thesis that all animals have the power, when there is a lack of individuals of one sex, of procreating an excess of individuals of this deficient sex, or, to put it in another way, that an excess of one sex determines the procreation of an excess of the other sex,—instituted experimental investigations regarding the determination of sex in the following manner (in accordance with a suggestion made by Pflüger): About ninety guinea-pigs were distributed in two pens in such a way that in one pen there was a great deficiency of males and a great excess of females, whilst in the other there was a deficiency of females and an excess of males. Thus the sexual ratios in the two stalls were opposed. In accordance with Düsing’s theory, therefore, more males should have been born in the first pen and more females in the second pen. Every week each pen was examined once or twice, the sex of the new-born young was ascertained, and they were distinguished by small incisions in the margin of the ear. A week later, when the young animals had developed a little further, they were re-examined to make sure that no mistake had been made.

At first, in the pen containing the original excess of females, there occurred a quite remarkable excess of male births. This, however, was merely the result of chance, for soon the relationships of the sexes among the new born was reversed, and thenceforward many more females were born than males. But if all the births occurring in this experiment are taken into consideration the number is still far too small to allow trustworthy conclusions to be drawn.

Düsing emphasizes the fact that such an experiment as this, in order to furnish results worth consideration, must be continued until the sexual ratio has become constant, so that it is no longer subject to alteration by chance variations. If we assume that Düsing’s theory is false, the results obtained would be the following: In both the pens, in that in which there was originally an excess of females and in that in which there was originally an excess of males, the births, if observed through a sufficient period, would present a definite sexual ratio which would be the same in both the pens. But if the theory is well founded the sexual ratio of the new born would vary in the two pens: in the stall in which there had originally been a deficiency of males there would be an excess of births of males over females; whereas in the pen in which there had originally been a deficiency of females there would on the contrary be an excess of births of females over males. Düsing recommends that for such experiments even more fruitful animals, such as rats and mice, should be utilized.

Institutes for pisciculture would also be extremely suitable for such experiments in breeding for the determination of the matter under discussion because, owing to the fact that in these animals fertilization is effected outside of the body of the parents, a direct examination of the ova and the semen used in the experiments can be undertaken, and the fertilization can be made to occur under conditions subjected to various alterations; also we can employ the roe and the sperm of fishes whose age, life history, weight and size are accurately known.

Much attention has recently been paid to the theory of Schenk, based, as he states, upon numerous experiments regarding the influences by which sex is determined. This observer also starts from the principle that ovulation is not independent of the influences of nutrition and metabolism. He believes that in the cases in which combustion in the body is effected in such a manner that remnants of unconsumed substances, still capable of heat-production, make their appearance in the urine, the ovum of the human female in process of formation is not so far advanced in its development as it is in cases in which the urine is entirely free from sugar, or at any rate is free from any demonstrable traces of the presence of this body. In the former case we shall find that the ovum is not only less mature, but also that it is presumably less well nourished. In his view such an ovum is less completely endowed in respect of the indwelling qualities and forces of its protoplasm, and it appears for this reason to be adapted only for the development of a female individual. But when, on the contrary, in the maternal individual, all the substances formed in and assimilated by the organism have undergone combustion so completely that there is no sugar in the urine, not even in the minutest discernible traces, the maternal body is in a condition suitable for the development of an ovum adapted to become a male individual. From these inferences, weak though the chain of argument is, Schenk draws the conclusion, that by the regulation of the nutritive material supplied to the organism, and by the suitable choice of that material, we are to a considerable extent enabled to support an ovum in its process of maturation in such a manner as to cause it to develop into a male individual.

The nutritive material selected for this purpose must be of such a nature that the elimination in the urine of even the minutest quantities of sugar may be prevented; the urine must appear free from sugar even when the phenyl-hydrazine test is employed. Thus in every case in which we wish to influence a woman’s nutrition in such a way as to lead to the procreation of a male individual we must above all ascertain whether, in the woman in question, the normal quantity of sugar is present in the urine. If after the most careful examination no trace of sugar can be found in the urine, and if reducing substances are present in this excretion in abundance, no change need be made in the diet, and all we have to do is to recommend that the requisite fertilization should be effected as soon as possible, since there is every probability that in this condition the embryo will prove to be of the male sex. But when, on the other hand the “normal” quantity of sugar is present in the urine, or when even traces only of that substance can be detected, it is necessary by changes in the diet to cause the disappearance from the urine of every trace of sugar, and at the same time to bring about the appearance in that fluid of an abundance of reducing substances. Schenk claims by the experiments he has made along these lines to have obtained results which show that it is possible in this way to influence the determination of sex.

His method is to nourish the mother mainly on nitrogenous materials and fat, and to give in addition only so much carbohydrate as is necessary to prevent the absence of this from being seriously felt. This diet should be continued for a considerable period, at best for two or three months before the fertilization is effected. After conception also, the same diet should be continued. In such a manner we are able in certain cases to bring about the procreation of male offspring. On the other hand, the desire for the procreation of female offspring remains one which as yet we have no direct means of fulfilling.

These vague experiments and ill-grounded theories of Schenk’s do not, as a matter of fact, constitute an important advance in the theory of the voluntary determination of the sex of the human offspring. What in reality are the decisive influences in the determination of sex, and how the final impulsion in one direction or the other is actually effected, remain altogether obscure. Prediction of the sex of the offspring, and the voluntary procreation of male or female infants, remain problems for the solution of which the most essential data are still lacking.

Ernest Hæckel writes regarding Schenk’s theory: “This important ‘discovery,’ which at the time of its first announcement attracted throughout the world an attention rarely given to true scientific advances, has now dwindled to the incomplete demonstration that the nutritive condition of the mother exercises a certain influence upon the determination of the sex of the child. But we knew this much a long time ago. Düsing and others, partly by physiological experiments and partly by statistical demonstrations, had shown that changes in the quantity and the quality of the nutriment supplied to either parent is capable of influencing the procreation of boys or girls. But if what Professor Schenk maintains were really true peoples living chiefly upon meat (as, for instance, in the pampas of South America) should have an exceptionally large proportion of male offspring; whereas those living mainly on a proteid-free diet (on meal, sugar, and other carbohydrates), should have an exceptionally large proportion of female offspring (as, for example, the rice-eating Indian and Mongolian nations). But this is by no means the case. And many other well-known facts are likewise opposed to the ‘epoch-making’ theory of Schenk. Whether the fertilized ovum develops into a boy or a girl, depends, I am convinced, upon far more complex, and to a large extent still entirely unknown, physiological causes. The final judgment upon the ‘Schenk theory’ must be, ‘Much Ado About Nothing.’”

Our exposition of the present standpoint of the doctrine of the origination of sex in the human species, has, in fact, shown that hitherto by statistical work, nor by anatomical investigations, nor, finally, by the experimental method, have results been obtained which render it possible to predict the sex of the unborn infant. And even in respect of the study of those influences which exercise a determining influence upon the origination of sex, no positive, indisputable conclusions have been reached. We can only say it appears probable that there exist several causes of the determination of sex the co-operative action of which proves effectual. Not in the ovum alone, nor in the spermatozoon alone, but in the reciprocal influence they exert one upon the other in the act of conception is sex determined. In the latter connection the relative and absolute ages of the progenitors appear to have a certain influence in the determination of the sex of the embryo; of importance also is the greater or less demand made upon the sexual capacity of the begetter; of influence too is the time at which the ovum is fertilized after its discharge from the ovary. It appears to be fairly well established that when the husband is at least ten years older than the wife, while the latter is at the age at which a woman’s reproductive powers are at a maximum, more boys are conceived than girls (Kisch); also that one of the progenitors upon whose sexual capacities the greater demands are made, tends to procreate an excess of individuals of his or her own sex (Piquet, Düsing); and, finally, that intercourse a considerable time after the cessation of the menstrual flow (in the second week of the intermenstrual interval or later) is favourable to the procreation of a male infant (Thury, Hensen). The influence of nutritive conditions in the determination of sex is less clearly established.

Statistical evidence has proved beyond dispute that given a sufficiently large number of instances in varying conditions the sexual ratio is 106, and this fact suggests that the determination of sex is dependent upon the interaction of two influences operating in opposite directions within narrow limits, in such a manner that the chances of the birth of a male infant preponderate over the chances of the birth of a female infant in the proportion of 106 to 100. In elucidation of this fact Hensen makes the following comparison: “Let us imagine a balance the beam of which has two arms of equal length; from the two extremities of this beam two balls of nearly equal weight begin to roll toward one another; if one ball rolls more quickly than the other, if one is lighter than the other, or if one starts to roll before the other, the opposite end of the beam will sink. The three influences are variously distributed; one influence may reinforce another, or may counteract another; but a decisive sinking of one end of the beam will always ultimately ensue. A minimal shortening or lightening of one arm of the balance will make the chance that the other arm will descend correspondingly greater.”

STERILITY IN WOMEN.

When we study the history of human civilization we find that sterility in women is regarded, not merely as a misfortune, but as a reproach. Among savage races, and in the Orient, where the position of women is one of strict subordination, she does not attain an honourable status until she becomes a mother. In Persia, a sterile woman is always divorced by her husband. In India, also, when a sterile married woman has in vain employed the various religious measures advocated for the relief of her barren condition she is sent back to her parents. Both in China and Japan, a barren woman is regarded as a most miserable creature. Among the negro races, a woman who fails to bear children is the object of scorn and contempt. Among the Dualla negroes, a man whose wife fails to bear children demands from her parents the return of the sum which he paid for her at the time of marriage. Many of the indigenous tribes of South America also make a practice of divorcing a sterile wife. Among the better-class Circassians, the women do not attain an assured position until they have borne a child. In Angola a barren woman is the object of universal contempt, and she often feels the ignominy of her position so keenly that she commits suicide. Alike among the Jews and among the Turks, barrenness in a wife is a recognized ground for divorce, and the woman who has been divorced for this reason will hardly ever succeed in obtaining another husband, for she is regarded as one whose body is not properly developed. According to old German law, barrenness in a wife and impotence in a husband were both grounds for divorce. The code of the Emperor Justinian allowed of divorce in cases in which for the space of two years a husband had been unable to fulfil his marital duties, and such a union was termed innuptæ nuptæ. Among the ancient Romans, although they regarded barrenness as a mark of the divine disfavour, according to the laws of Augustus failure to bear children was a punishable offence, and such a punishment was incurred by any married woman who had attained the age of 20 years without having become a mother. In ancient Greece also, divorces due to the barrenness of the wife were by no means uncommon. Among the Slavonic peoples sterility was so greatly despised that there is a Slavonic proverb which runs: “A woman is no woman until she has borne a child”: and in Istria a sterile woman is known by the nickname “Scirke,” which is equivalent to “hermaphrodite.” The Jewish view of the matter is expressed in the Talmudic rabbinical saying: “A wife’s duties are beauty, gentleness, and the bearing of children”; and again, “the poor, the leprous, the blind, and the childless, are like the dead”; and, finally, “he who refrains from marriage with the deliberate intention of having no children, incurs the guilt of murder.” In the Koran we find the fatalistic expression, “God makes a woman barren in accordance with his will.”

We can therefore readily understand that in the most ancient medical writings the question of sterility in women is a matter of earnest consideration. In the works of the early physicians of Hindustan we find several apt remarks on the subject. Susruta says: “Pregnancy most readily results from intercourse during menstruation. At this time the os uteri is open, like the flower of the water lily in the sunshine.” In the Old Testament, in which the newly-created human couples receive the command, “Be fruitful and multiply, and replenish the earth,” we find frequent references to barrenness as a state equally dishonourable and unfortunate, and the use of certain plants is recommended as a means of cure. The Talmud contains several essays dealing with the causes and treatment of sterility.

The Hippocratic collection of writings contains a number of passages dealing with the causes of sterility and with the means to be employed for its relief. We shall have occasion later to refer to these recommendations. Celsus, on the other hand, has little to say on this subject. In the works of Pliny, and also in those of Aristotle, there are references to the topic of sterility.

Among the writers of the first century of our era, Soranus discusses exhaustively the capacity for conception and sterility. In his work we find, among other passages, the unquestionably accurate remark: “Since the majority of marriages are concluded, not from love, but in order to procreate children, it is difficult to understand why, in the choice of a wife, less regard is paid to her probable fertility than to the worldly wealth of her parents.”

In the middle ages, Paulus Agineta more especially treats of the diseases of women, and among these, of sterility in women. That in Arabian medicine much attention was paid to this question, we can learn from the writings of Maimonides.

By sterility in women we understand the pathological state in which a woman who is sexually mature fails to conceive, notwithstanding frequently repeated, normal sexual intercourse throughout a considerable period of time.

Sterility is termed congenital (or absolute) when, notwithstanding repeated intercourse throughout a long period (not less than three years), pregnancy has always failed to ensue; it is termed acquired (or relative), when women who have already been pregnant once or more often, cease to conceive, although they are still quite young enough to do so, and have experienced regular sexual intercourse for a long period (not less than three years). In a wider sense of the term, we say that a woman is sterile, when, notwithstanding prolonged and repeated sexual intercourse, in circumstances favourable to procreation, she has failed to give birth to a living and viable infant.

English authors also make a special distinction regarding that form of acquired sterility (which is no great rarity), in which a woman gives birth to a single infant and subsequently remains sterile (“only-child sterility”).

The civilization of the present day, with its shady side, has made it necessary for us to pay an increasing attention to facultative sterility, dependent upon the use during intercourse of means for the prevention of conception; and very recently the surgical tendency of modern gynecology has brought into being a new variety of sterility in women, viz., operative sterility.