Mr. 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. Romanes regards it as a moral certainty that disuse has no transmitted effect in reducing an organ, and it should follow that he holds use to have no transmitted effect in its development. The sequel, however, makes me uncertain how far Mr. Romanes intends this, and I would refer the reader to the article which Mr. Romanes has just published on Weismann in the Contemporary Review for this current month. The burden of Mr. Thiselton Dyer's controversy with the Duke of Argyll (see Nature, January 16, 1890, et seq.) was that there was no evidence in support of the transmission of any acquired modification. The orthodoxy of science, therefore, must be held as giving at any rate a provisional support to Professor Weismann, but all of them, including even Professor Weismann himself, shrink from committing themselves to the opinion that the germ-cells of any organisms remain in all cases unaffected by the events that occur to the other cells of the same organism, and until they do this they have knocked the bottom out of their case. From among the passages in which Professor Weismann himself shows a desire to hedge I may take the following from page 170 of his book:-- "I am also far from asserting that the germ-plasm which, as I hold, is transmitted as the basis of heredity from one generation to another, is absolutely unchangeable or totally uninfluenced by forces residing in the organism within which it is transformed into germ-cells. I am also compelled to admit it as conceivable that organisms may exert a modifying influence upon their germ-cells, and even that such a process is to a certain extent inevitable. The nutrition and growth of the individual must exercise some influence upon its germ-cells . . . " Professor Weismann does indeed go on to say that this influence must be extremely slight, but we do not care how slight the changes produced may be, provided they exist and can be transmitted. On an earlier page (p. 101) he said in regard to variations generally that we should not expect to find them conspicuous; their frequency would be enough, if they could be accumulated. The same applies here, if stirring events that occur to the somatic cells can produce any effect at all on offspring. A very small effect, provided it can be repeated and accumulated in successive generations, is all that even the most exacting Lamarckian will ask for.