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Updated: May 19, 2025
Professor Weismann's theory is, that at every new birth a part of the substance which proceeds from parents and which goes to form the new embryo is not used up in forming the new animal, but remains apart to generate the germ-cells or perhaps I should say "germ-plasm" which the new animal itself will in due course issue.
Wallace should categorically deny that their effects were inheritable. On the other hand, the temptation to adopt Professor Weismann's view must have been overwhelming to one who had been already inclined to minimise the effects of use and disuse. On the whole, one does not see what Mr. Wallace could do, other than what he has done unless, of course, he changed his title, or had been no longer Mr.
The germ-cells are thus the bearers of heredity because they contain samples, so to speak, of all the organs of the body. In heredity, according to Weismann's theory, the egg is the centre of control, the continuous germ-plasm the source of all transmitted changes; according to Darwin's theory, the body is the source, and the egg is derived in great part at least from it.
Furthermore, as Osborne has insisted, linear variations, or variations proceeding along certain single and well-marked lines, would seem inexplicable by, if not fatal to, Weismann's theory. And yet Osborne, Cope, and others have shown that the teeth of mammals have developed steadily along well-marked lines.
Arguments from social structures, from cosmic, natural and human history, much of it deduced by analogy, were jumbled together in a fashion which seems amazing to us now, though common enough thirty years ago. In 1903, Weismann's theory of the continuity of the germplasm was ten years old.
Romanes, writing in Nature, March 13, 1890, and opposing certain details of Professor Weismann's theory, so far supports it as to say that "there is the gravest possible doubt lying against the supposition that any really inherited decrease is due to the inherited effects of disuse." The "gravest possible doubt" should mean that Mr.
Weismann's original treatise, as well translated and still further enlarged by Mr. Raphael Meldola, but will present them instead with a brief résumé, boiled down and condensed into a patent royal elixir of learning.
Experiments dealing with the phenomena of heredity in pure and mixed breeds have largely confirmed Weismann's doctrine, and they have prepared the way for a deeper investigation of the marvelous process of biological inheritance.
Weismann's explanation that the parents are not the creators of the germs but, on the contrary, that the germs existed before the birth of the body, before the growth of the body, in previous generations, or in the common stock of the universe. The previous generations are dead and gone, so we may say that they existed in the universe.
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.
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