The sexual life of woman in its physiological, pathological and hygienic aspects

by E. Heinrich Kisch

Ploss, in an article on “The Causes of Variations in the Sexual Ratio,” published in twelfth volume of the “Berliner geburtsh. Monatsheft,” has collected a number of statistical data to demonstrate that the determination of sex is principally dependent upon the nutritive condition of the mother. In his opinion the determination of the sex of the embryo depends neither upon the quality of the ovum nor upon that of the spermatozoon, nor again upon the reciprocal influences exerted by ovum and spermatozoon on one another. During the earliest time after fertilization the embryo is sexually neutral and only later, as a result of some new influence acting upon it, does it receive an impulse toward the formation either of the male or of the female sex. Among all the external conditions which are capable during this period of exercising a determinative influence the most important are the nutritive conditions, for nutrition is the most important factor in determining the form of the young animal, and most of the other outward conditions, such as light, heat, and chemical changes, affect the embryo in a mediate manner only, through the changes they are respectively capable of inducing in its nutrition and metabolism. But Ploss is not content with asserting that the nutritive condition of the mother is of great importance in determining the sex of the embryo; he goes further than this, and declares that it is scanty nutrition of the mother which especially gives rise to the birth of males, whereas abundant nutrition of the mother tends to give rise to the birth of females. He refers to observations made in respect of other animals than man. St. Hilaire observed that among the underfed animals in menageries there was an excess of male births. Hofacker and Girou de Bazarcingues have noted similar phenomena in the case of domestic animals; they found that when these were richly fed they gave birth to an excess of females, but that when they were poorly nourished they gave birth, on the contrary, to an excess of males. Among sheep, with whom the number of male and of female births is approximately identical, Martegoute found that those animals which had given birth to female lambs had on the average a greater weight than those ewes which had given birth to male lambs. During the period of lactation, also, the former lost weight more than the latter.

When Ploss had further ascertained that among those engaged in the fur-trade it is the established belief that from fruitful regions the skins chiefly of female animals will be obtained, but from barren regions, on the other hand, among the skins obtained those of male animals will preponderate, it appeared to him that he was justified in drawing the conclusion that among the mammalia a well-nourished mother, one capable of providing abundant nutriment for her offspring, is, on the whole, more likely to give birth to a female than to a male, and conversely. He then endeavoured, by reference to the statistics of population, to show that in the case of human beings also, when the mother is exceptionally well nourished, there is especial likelihood of a girl being born; whereas when the mother is ill nourished she is more likely to give birth to a boy—odd as it may seem, at first sight, that a rich diet should determine the production of the so-called less powerful sex, the female; and conversely. (Ploss, be it noted however, denies that male new-born infants are more powerful than female.) The fact that in the country, comparatively speaking, many more boys are born than in towns (vide supra) is explained by Ploss as dependent on the fact that townswomen are on the whole better nourished than the countrywomen, owing to the greater consumption of meat by the former.

The circumstance again (likewise alluded to above), that in the case of illegitimate births almost always the excess of male births is less marked than in the case of the offspring of legal unions, is regarded by Ploss as offering further proof of the influence of nutritive conditions upon the determination of sex. Illegitimate mothers are on the average women at the very best age for child-bearing, women who have worked vigorously, are themselves well nourished, and are therefore better able to nourish their unborn offspring than (on the average) married women. Further, it is a remarkable fact that in Saxony, regions of which the elevation above the sea-level is less than 1,000 feet, produce comparatively more girls than regions at an altitude of 1,000 to 2,000 feet above the sea. This Ploss refers to the worse nutrition of the women living at the higher altitude, for the fact is well known that the higher we go above the sea the less fertile is the soil and the more limited is its produce.

Starting from the view that the lower classes of the population are in good years better nourished than they are in bad years, Ploss compared statistically the rise and fall of the prices of foodstuffs, in Saxony, with the variations of the sexual ratio in the same kingdom; and he found, in correspondence with his theory, that in bad times there was a greater excess of male births than there was during periods in which food was cheaper. Moreover, the consumption of meat appeared to have more influence upon the variations in the sexual ratio than was exercised by the consumption of vegetable foodstuffs. Ploss endeavoured to show graphically that with an increase in the price of provisions there corresponded an increase in the excess of male births, and vice versa.

That after times of great wars, pestilence, and emigration, in which the male portion of the population has been decimated, there occurs a notable increase in the excess of male births, is explained by Ploss by the assumption that in consequence of the deficiency of male labour, the general supply of provisions is deficient, just as it is after years of bad harvests; hence, in consequence of the scanty nutrition of the mothers, the number of female births is depressed and the number of male births increases. Those countries which in general possess a more thriving population, such as Saxony, England, Belgium, Prussia, etc., exhibit a smaller excess of male births when compared with those countries in which a more widespread poverty exists, such as Russia, Lombardy, Bohemia, and even France. With increasing prosperity, fruitfulness increases, and there is an increase also in the proportion of female births.

These views of Ploss’s are, however, rightly contested by Breslau and Wappaeus.

Breslau (“The Causes of the Determination of Sex”) offers in the first place theoretical objections to the view that nutritive conditions in the mother are determinative in the production of the sex of the offspring; and he then proceeds to quote statistical data which are opposed to any such theory. He rightly insists, in the first place, that, inasmuch as it is unquestionable that in the act of fertilization the spermatozoon induces in the ovum certain changes, the effect of which is manifested in days far later than those of intra-uterine life, by the production of the most manifold and various somatic and psychical resemblances to the father, it is obvious that this single occurrence of the fusion of the spermatozoon, the bearer of the paternal influences, with the ovum is competent to induce in the ovum a molecular arrangement upon which the determination of sex may be supposed to depend—it is not necessary to suppose that for this determination, repeated actions, or a prolonged period of time, is requisite.

In this connection a reference to birds is instructive, for in this division of the animal kingdom we seem absolutely compelled to assume that the sex of the offspring is irrevocably determined in the moment of fertilization. “In birds, who lay an egg every day, eggs which are kept all at the same temperature during the period of incubation, and some of which develop into cock and others into hen birds—how is it possible to imagine that the nutritive condition of the parent is determinative of the sex of the offspring, since this nutritive condition cannot reasonably be supposed to change to any notable extent from one day to the next and then back again?”

The paternal influence in the determination of sex is regarded by Breslau as likely to be at least as important as that exercised by the mother. Unquestionably the semen is subject to certain variations in quality and in quantity, and it is possible that these variations may make themselves felt in the subsequent development of the embryo. Of the semen, as of all secretions, we can assume with some probability that in certain conditions (conditions which are, indeed, but little understood), it may exhibit a greater or less intensity in its stimulating qualities, and that in this way it may be subject to changes, according to which it will tend to influence the development of the embryo, now in the female, and now in the male direction. Again, in view of the continued interchange of nutritive materials between the embryo and the maternal organism, it is probable enough that the constitution of the maternal organism and likewise that of the ovum, at the moment of fertilization, are not matters of indifference to the determination of sex. But to attribute to the nutritive condition of the maternal organism the sole or even the principal influence in the determination of the sex is an unjustifiable assumption.

The proofs alleged by Ploss from the animal world in support of his thesis, viz., that in the case of poorly nourished animals there is a marked excess of male offspring, are justly controverted by Breslau with the remark that the observations on animals are but few in number, and further that we know nothing whatever regarding the normal sexual ratios among the offspring of such animals as lions, tigers, hyænas, bears, etc., in the free state.