Part 54

To a certain extent we can trace the influence of climate and of season upon fertility. Heat appears to favour fertility; Haycraft’s figures for the eight largest towns of Scotland show clearly how the number of conceptions rises and falls pari passu with the temperature. Lower animals also, when brought from a colder to a warmer neighbourhood, exhibit an earlier and more frequently recurring “heat.” In Europe, however, the Northern races appear more fertile than those of the south.

Of the seasons, spring is the one especially favourable to fertility. Quetelet, who proves by numerous statistical data that the maximum of conceptions occurs in May, attributes this fact to a general increase in the vital forces occurring in spring, after the cold of winter. Villermé, however, goes back to the older explanation, that the increase in the number of conceptions in May and June is due to social and economic conditions. The return of spring, especially the end of spring and the beginning of summer, a time of year in which the means of subsistence are provided in exceptional quantity, and of especially good quality, the season also of festivals and social reunion, when the two sexes are brought into more intimate contact and when the majority of marriages occur—these are the conditions associated with the season of greatest fertility. The figures of Wappaeus also confirm the influence of spring in favouring fertility. He found, however, that there were two seasons of maximal fertility. The first at the end of spring and the beginning of summer; the second in winter, especially in December. Mid-winter is for most people a period of domestic amusement and relaxation, one of exceptionally good nutrition, and of social reunion; the spring increase in fertility is a part of the awakening and increase of the reproductive forces of nature at large, which recurs every spring-time.

Every marked and sudden change in the mode of life has an unfavourable influence on fertility. Darwin reports that mares who have for some time been stall-fed with dry fodder and are then put out to grass are at first infertile after the change. Europeans going to reside in the tropics experience a notable decline in fertility as a result of the change of climate. According to Virchow, the fertility of European women who become acclimatized in the tropics declines very gradually, but in the course of a few generations is almost completely annulled.

The marriage of near kin is believed also to diminish fertility. As regards inbreeding in the lower animals, it is well known that when nearly related animals copulate, the number of the offspring is below the average. Nathusius paired a sow with its own uncle, the boar having proved productive in intercourse with other sows; the litter numbered five to six only. This sow, which belonged to the great Yorkshire race, was then paired with a small black boar, which in intercourse with sows of its own variety had procreated litters numbering six or seven; as a result of her first pairing with the black boar, the sow cast a litter numbering twenty-one whilst the second attempt produced a litter of eighteen. Similar results were obtained by Crampe, in his experiments in the inbreeding of rats.

Some authorities declare that the results of inbreeding are similar in the human species, that the marriages of near kin are less fruitful than the average. Darwin writes in this connection: “With regard to human beings, the question whether breeding in-and-in is also deleterious, will probably never receive a direct answer, for man reproduces his kind so very slowly, and cannot be made the object of experiment. The very general disinclination of nearly all races to the marriage of near kin, which has existed from the very earliest times, is of weight in relation to this question. Indeed we appear almost justified in applying to the human race the experience gained by experiment on the higher mammals.”

Darwin’s assumption regarding the effect upon fertility of the marriage of near kin in the human species, cannot, however, be accepted without qualification. In ancient times there was no uniformity of opinion on this topic. It is well known that among the Phœnicians, a son might marry his mother, and a father his daughter; and among the ancient Arabs it was the legal duty of the son to marry his widowed mother. Moses, on the contrary, forbade marriages between parents and children, between brothers and sisters, also marriage with a father’s sister, with a wife’s mother, and with an uncle’s widow.

Darwin considered that the marriage of first cousins was not unfavourable to fertility. Of 97 such marriages, 14 were sterile, whilst of 217 marriages of those not akin, 35 were sterile; the percentage in both cases being almost identical. Mantegazza, who regards kinship in marriage as unfavourable to fertility, found nevertheless that among 512 marriages of near kin, only 8 to 9% were sterile. It is widely believed that the dying out of many aristocratic families is dependent on the inbreeding so common in this class—but it must be admitted that scientific evidence in support of this belief is lacking. Incest in the human species may certainly result in fertilization. Among the Jews, marriages of near kin are very common, and often prove extremely fruitful.

Göhlert made a statistical investigation of the fertility of the reigning families of Europe, in order to throw light on this question. In the Capet dynasty, 118 marriages of near kin took place, and of these 41 were sterile; in the Wettin dynasty (Saxony), there were 28 such marriages, of which 7 were sterile, and 1 produced one child only; in the Wittelsbach dynasty (Bavaria), 29 such marriages, of which 9 were sterile, and 3 produced only one child each. Thus of 175 marriages of near kin, 57, or 32.6% remained sterile. Further, in the Habsburg-Lothringen dynasty, of 110 marriages, 25 were marriages of near kin, and of these 33% remained sterile.

It has been assumed since the days of antiquity that temperament and constitution exercise some influence on fertility. Hippocrates, Soranus, and Diokles, are among the ancient authors who refer to this matter. Soranus says very justly: “Since most marriages are contracted, not from love, but for the procreation of children, it is irrational, when choosing a wife, to have regard, not to her probable fruitfulness, but instead of this to the social position and the wealth of her parents.”

It would appear that a certain dissimilarity in physical constitution and temperament between husband and wife is favourable to the fertility of the marriage. For instance, a vivacious, dark husband, and a lethargic, fair wife, are better suited to one another than a husband and wife both extremely active, or both of extremely phlegmatic temperament.

Toussaint Loua published the following figures regarding the fertility of the women of the various countries of Europe:

══════════════╤═════════════╤═════════════════════════════════════════ │ Number of │ COUNTRY. │ births per │FERTILITY OF WOMEN BETWEEN THE AGES OF 15 │ hundred │ AND 45 YEARS. │inhabitants. │ ──────────────┼─────────────┼─────────────┬─────────────┬───────────── „ │ „ │ Married. │ Unmarried. │ Average. ──────────────┼─────────────┼─────────────┼─────────────┼───────────── Hungary │ 4.94│ │ │ 17.8 Russia │ 4.12│ │ │ 20.5 Austria │ 3.93│ │ │ 16.4 Germany │ 3.77│ 34.8│ 2.9│ 17.7 Italy │ 3.67│ 28.8│ 2.4│ 16.1 Holland │ 3.67│ 35.3│ 1.0│ 16.0 Finland │ 3.63│ │ │ 15.8 England │ 3.58│ 29.7│ 1.6│ 15.5 Scotland │ 3.53│ 32.8│ 2.5│ 15.8 Belgium │ 3.25│ 33.7│ 1.8│ 14.8 Denmark │ 3.12│ 28.5│ 2.8│ 14.4 Roumania │ 3.12│ │ │ 13.5 Norway │ 3.10│ 29.3│ 2.2│ 14.0 Sweden │ 3.05│ 29.1│ 2.5│ 13.7 Switzerland │ 3.04│ 29.7│ 1.1│ 13.1 Greece │ 2.96│ │ │ 13.2 Ireland │ 2.69│ 29.8│ 0.5│ 12.3 France │ 2.63│ 20.3│ 1.8│ 11.6 ══════════════╧═════════════╧═════════════╧═════════════╧═════════════

In towns, conjugal fertility is less, extra-conjugal fertility greater, than in the country. An increase in factory labour gives rise to an increase in the population, but to a decline in the vitality of the offspring; that is to say, it causes a quantitative increase, and a qualitative decrease, in fertility. An increase in agricultural labour has precisely the opposite effect. The influence of war upon fertility is unfavourable both quantitatively, and qualitatively. According to Tschouriloff, the introduction of universal military service, by withdrawing for a time all the most vigorous men from domestic life, tends to diminish fertility. Extensive emigration from a country in which the soil is fertile, and where the vital conditions are generally favourable, is stated by Bertillon to cause an increased fertility in the mother country; he further states that an increase in the number of the proprietors of the soil is followed by diminished fertility, and vice versa.

Prostitutes show as a rule a very low fertility. According to the data of Tarnowskaja, the fertility of prostitutes in Russia is 34%, whilst married women of similar ages in Russia exhibit a fertility of 51.8%. Gurrieri found 60% of prostitutes childless.

The fertility of female criminals was found by Lombroso to be undiminished. On the average, poisoners had given birth to 4.5 children, other murderesses to 3.2 children, child-murderesses to 2 children; thus the prisoners whose crime is commonly dependent on an abnormal eroticism had a fertility above the average.

The diminished fertility of prostitutes depends in part upon frequent venereal infection, in part upon the unfavourable influence of the mercury and iodide of potassium administered for the cure of such infection, also upon the frequency with which they consume excessive quantities of alcohol, upon the excessive frequency of coitus, which exercises a traumatic influence, upon the irregular mode of life, and upon their disinclination to be burdened with children.

Conjugal fertility, that is to say, the ratio between legitimate births and the number of married women between the ages of 15 and 50 years, has declined in Germany during the last decades. It was:

During the years 1872 to 1875 29.7% During the years 1879 to 1882 27.4% During the years 1889 to 1892 26.5%

This decline is small, but it is much more manifest in urban than in rural districts. This fact is shown by the following figures, relating to fertility in Prussia:

1872 to 1879. 1894 to 1897. In all towns 26.9 24.0 In Berlin 23.8 16.9 In other large towns 26.7 23.5 In rural districts 28.8 29.0

This difference depends principally on the fact that in the large towns of Germany (and still more in those of France) the use of means for the prevention of pregnancy is continually increasing, whereas the population of the rural districts is as yet less familiar with the use of these measures.

According to Hellstenius, conjugal fertility, that is, the number of children per married couple, is as follows:

In the Netherlands 4.88 Norway 4.70 Prussia 4.60 Bavaria 4.55 Sweden 4.52 Saxony 4.35 England 4.33 Belgium 4.23 Denmark 4.18 France 3.46

Talquist, who has published a statistical investigation concerning the modern tendency to diminished fertility, arrives at lower figures than Hellstenius. According to him, conjugal fertility is:

In Prussia 4.11 England 4.10 Belgium 4.12 France 2.09 In various States of the American Union 2.5 to 3.0

From the Almanach de Gotha Vacher obtained figures showing that each family of the higher aristocracy has on the average the following number of children.

In France 2.0 Italy 3.0 Germany 4.8 England 4.9 Russia 5.1

According to the figures we have published, the fertility of women suffices for the production during the sexual life of a small number only of children, averaging, in fact, 4 to 5 children per marriage. Many mothers, however, give birth to a very large number of children. Among 73,000 families inhabiting Buda-Pesth, Körösi found 300 mothers who had had 15 children or more; 7 mothers who had each had 21 children; and 3 mothers who had given birth respectively to 22, 23 and 24 children.