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On a still later page, however, we read:–

“If, for instance, it could be shown that artificial mutilation spontaneously reappears in the offspring with sufficient frequency to exclude all possibilities of chance, then such proof [i.e., that acquired characters can be transmitted] would be forthcoming. The transmission of mutilations has been frequently asserted, and has been even recently again brought forward, but all the supposed instances have broken down when carefully examined” (p. 390).

Here, then, we are told that proof of the occasional transmission of mutilations would be sufficient to establish the fact, but on p. 267 we find that no single fact is known which really proves that acquired characters can be transmitted, “for the ascertained facts which seem to point to the transmission of artificially produced diseases cannot be considered as proof” [Italics mine.] Perhaps; but it was mutilation in many cases that Professor Weismann practically admitted to have been transmitted when he declared that Obersteiner had verified Brown-Sequard’s experiments.

That Professor Weismann recognises the vital importance to his own theory of the question whether or no mutilations can be transmitted under any circumstances, is evident from a passage on p. 425 of his work, on which he says: “It can hardly be doubted that mutilations are acquired characters; they do not arise from any tendency contained in the germ, but are merely the reaction of the body under certain external influences. They are, as I have recently expressed it, purely somatogenic characters–viz., characters which emanate from the body (soma) only, as opposed to the germ-cells; they are, therefore, characters that do not arise from the germ itself.

“If mutilations must necessarily be transmitted” [which no one that I know of has maintained], “or even if they might occasionally be transmitted” [which cannot, I imagine, be reasonably questioned], “a powerful support would be given to the Lamarckian principle, and the transmission of functional hypertrophy or atrophy would thus become highly probable.”

I have not found any further attempt in Professor Weismann’s book to deal with the evidence adduced by Mr. Darwin to show that mutilations, if followed by diseases, are sometimes inherited; and I must leave it to the reader to determine how far Professor Weismann has shown reason for rejecting Mr. Darwin’s conclusion. I do not, however, dwell upon these facts now as evidence of a transmitted change of bodily form, or of instinct due to use and disuse or habit; what they prove is that the germ- cells within the parent’s body do not stand apart from the other cells of the body so completely as Professor Weismann would have us believe, but that, as Professor Hering, of Prague, has aptly said, they echo with more or less frequency and force to the profounder impressions made upon other cells.

I may say that Professor Weismann does not more cavalierly wave aside the mass of evidence collected by Mr. Darwin and a host of other writers, to the effect that mutilations are sometimes inherited, than does Mr. Wallace, who says that, “as regards mutilations, it is generally admitted that they are not inherited, and there is ample evidence on this point.” It is indeed generally admitted that mutilations, when not followed by disease, are very rarely, if ever, inherited; and Mr. Wallace’s appeal to the “ample evidence” which he alleges to exist on this head, is much as though he should say that there is ample evidence to show that the days are longer in summer than in winter. “Nevertheless,” he continues, “a few cases of apparent inheritance of mutilations have been recorded, and these, if trustworthy, are difficulties in the way of the theory.” . . . “The often-quoted case of a disease induced by mutilation being inherited (Brown-Sequard’s epileptic guinea-pigs) has been discussed by Professor Weismann and shown to be not conclusive. The mutilation itself–a section of certain nerves–was never inherited, but the resulting epilepsy, or a general state of weakness, deformity, or sores, was sometimes inherited. It is, however, possible that the mere injury introduced and encouraged the growth of certain microbes, which, spreading through the organism, sometimes reached the germ-cells, and thus transmitted a diseased condition to the offspring.” {35}