A man is born sober—in most cases, but not always,[57] as we shall see—and any changes produced in his body by alcohol are “acquired.” Therefore, rejecting Lamarck, are we to reject the doctrine that the effects produced by alcohol on parents are transmitted to offspring?
The controversy between Lamarck and Weismann has absolutely nothing to do with the question. Let us consider what would be a case of Lamarckian transmission in the sense which the modern student of heredity denies. The birth of a child with a scar on its scalp, to a father who had acquired a similar scar before the child was conceived, would be such a case: and this does not happen. Or suppose that instead of a scar on the scalp the father has an inflammatory change, not so dissimilar to a scar, produced by alcohol in the membranes covering his brain. Then it would be a case of Lamarckian transmission if the membranes of his baby's brain were similarly affected; and this does not happen. Such is the kind of transmission of which exhaustive experiment and observation fail to find a conclusive instance anywhere.
But what has such a supposition to do with the theory, as definitely supported by observation and experiment as the other is not, that if a man saturates his body with alcohol carried by his blood, he injures all the tissues which are nourished by that blood, including the racial elements of his body with the rest: and therefore that his child may be degenerate?
What says Weismann himself? In The Germ-Plasm, p. 386, under the heading “The influence of temporary abnormal conditions of the parents on the child,” he writes as follows:—
“Although I do not consider that the cases which come under the above heading have anything to do with heredity, I should not like to leave them entirely on one side.
“It has often been supposed that drunkenness of the parents at the time of conception may have a harmful effect on the nature of the offspring. The child is said to be born in a weak bodily and mental condition, and inclined to idiocy, or even to madness, etc., although the parents may be quite normal both physically and mentally.
“Cases certainly exist in which drunken parents have given rise to a completely normal child, although this is not a convincing proof against the above-named view; and in spite of the fact that most, or perhaps even all, the statements with regard to the injurious effects on the offspring will not bear a very close criticism,[58] I am unwilling to entirely deny the possibility that a harmful influence may be exerted in such cases. These, however, have nothing to do with heredity, but are concerned with an affection of the germ by means of an external influence.”
Weismann goes on to quote cases showing how germ-cells may be injured by various agents, and continues:—
“It does not appear to me impossible that an intermixture of alcohol with the blood of the parents may produce similar effects on the ovum and sperm cell. According to the relative quantity of alcohol either an exciting or a depressing influence might be exerted, either of which would lead to abnormal development....