Again, T. A. MacNicholl reported on 55,000 American school children, from 20,147 of whom he secured information about the parents' attitude to alcoholic drinks. He found an extraordinarily large proportion (58%) of deficient and backward children in the group. But the mere bulk of his work, probably, has given it far more prestige than it deserves; for his methods are careless, his classifications vague, his information inadequate; he seems to have dealt with a degenerate section of the population, which does not offer suitable material for testing the question at issue; and he states that many of the children drank and smoked,—hence, any defects found in them may be due to their own intemperance, rather than that of their parents. In short, Dr. MacNicholl's data offer no help in an attempt to decide whether alcoholism is an inheritable effect.
Another supposed piece of evidence which has deceived a great many students is the investigation of Bezzola into the distribution of the birth-rate of imbeciles in Switzerland. He announced that in wine-growing districts the number of idiots conceived at the time of the vintage and carnival is very large, while at other periods it is almost nil. The conclusion was that excesses of drunkenness occurring in connection with the vintage and carnival caused this production of imbeciles. But aside from the unjustified assumptions involved in his reasoning, Professor Pearson has recently gone over the data and shown the faulty statistical method; that, in fact, the number of imbeciles conceived at vintage-time, in excess of the average monthly number, was only three in spite of the large numbers! Bezzola's testimony, which has long been cited as proof of the disastrous results of the use of alcohol at the time of conception, must be discarded.
Demme's plausible investigation is also widely quoted to support the belief that alcohol poisons the germ-plasm. He studied the offspring of 10 drunken and 10 sober pairs of parents, and found that of the 61 children of the latter, 50 were normal, while of the 57 progeny of the drunkards, only nine were normal. This is a good specimen of much of the evidence cited to prove that alcohol impairs the germ-plasm; it has been widely circulated by propagandists in America during recent years. Of course, its value depends wholly on whether the 20 pairs of parents were of sound, comparable stock. Karl Pearson has pointed out that this is not the case. Demme selected his children of drunkards by selecting children who came to his hospital on account of imperfect development of speech, mental defect, imbecility or idiocy. When he found families in which such defective children occurred, he then inquired as to their ancestry. Many of these children, he found, were reduced to a condition approaching epilepsy, or actually epileptic, because they themselves were alcoholic. Obviously such material can not legitimately be used to prove that the use of alcohol by parents injures the heredity of their children. The figures do not at all give the proof we are seeking, that alcohol can so affect sound germ-plasm as to lead to the production of defective children.
Dr. Bertholet made a microscopic examination of the reproductive glands of 75 chronic male alcoholics, and in 37 cases he found them more or less atrophied, and devoid of spermatozoa. Observing the same glands in non-alcoholics who had died of various chronic diseases, such as tuberculosis, he found no such condition. His conclusion is that the reproductive glands are more sensitive to the effects of alcohol than any other organ. So far as is known to us, his results have never been discredited; they have, on the contrary, been confirmed by other investigators. They are of great significance to eugenics, in showing how the action of natural selection to purge the race of drunkards is sometimes facilitated in a way we had not counted, through reduced fertility due to alcohol, as well as through death due to alcohol. But it should not be thought that his results are typical, and that all chronic alcoholists become sterile: every reader will know of cases in his own experience, where drunkards have large families; and the experimental work with smaller animals also shows that long-continued inebriety is compatible with great fecundity. It is probable that extreme inebriety reduces fertility, but a lesser amount increases it in the cases of many men by reducing the prudence which leads to limited families.
In 1910 appeared the investigation of Miss Ethel M. Elderton and Karl Pearson on school children in Edinburgh and Manchester.[22] Their aim was to take a population under the same environmental conditions, and with no discoverable initial differentiation, and inquire whether the temperate and intemperate sections had children differing widely in physique and mentality. Handling their material with the most refined statistical methods, and in an elaborate way, they reached the conclusion that parental alcoholism does not markedly affect the physique or mentality of the offspring as children. Whether results might differ in later life, their material did not show. Their conclusions were as follows:
"(1) There is a higher death-rate among the offspring of alcoholic than among the offspring of sober parents. This appears to be more marked in the case of the mother than in the case of the father, and since it is sensibly higher in the case of the mother who has drinking bouts [periodical sprees] than of the mother who habitually drinks, it would appear to be due very considerably to accidents and gross carelessness and possibly in a minor degree to toxic effect on the offspring.
"Owing to the greater fertility of alcoholic parents, the net family of the sober is hardly larger than the net family of the alcoholic. [It should be remembered that the study did not include childless couples.]
"(2) The mean weight and height of the children of alcoholic parents are slightly greater than those of sober parents, but as the age of the former children is slightly greater, the correlations when corrected for age are slightly positive, i.e., there is slightly greater height and weight in the children of the sober."
"(3) The wages of the alcoholic as contrasted with the sober parent show a slight difference compatible with the employers' dislike for an alcoholic employee, but wholly inconsistent with a marked mental or physical inferiority in the alcoholic parent.
"(4) The general health of the children of alcoholic parents appears on the whole slightly better than that of sober parents. There are fewer delicate children, and in a most marked way cases of tuberculosis and epilepsy are less frequent than among the children of sober parents. The source of this relation may be sought in two directions; the physically strongest in the community have probably the greatest capacity and taste for alcohol. Further the higher death rate of the children of alcoholic parents probably leaves the fittest to survive. Epilepsy and tuberculosis both depending upon inherited constitutional conditions, they will be more common in the parents of affected offspring, and probably if combined with alcohol, are incompatible with any length of life or size of family. If these views be correct, we can only say that parental alcoholism has no marked effect on filial health.