Hence, we can only conclude that there is no evidence in favour of the hypothesis that germ-plasm has been unalterably stable “since the first origin of sexual propagation”; while the suggestion that it may have been so is on antecedent grounds improbable, and on inductive grounds untenable. It only remains to add that the _degree_ of stability has been proved in not a few cases to be less than even the theory of gemmules might anticipate. Many facts in proof of this statement might be given, but it will here suffice to quote one, which I select because it has been dealt with by Professor Weismann himself. Professor Hoffmann has published an abstract of a research, which consisted in subjecting plants with normal flowers to changed conditions of life through a series of generations. In course of time, certain well-marked variations appeared. Now, in some cases such directly-produced variations were transmitted by seed from the affected plants; and therefore Weismann acknowledges,—“I have no doubt that the results are, at any rate in part, due to the operation of heredity.” Hence, whether these results be due to the transmission of somatogenetic characters (“representative changes”), or to the direct action of changed conditions of life on the germ-plasm itself (“specialized changes”), it is equally certain that the hereditary characters of the plants were congenitally modified to a large extent, within (at most) a few generations. In other words, it is certain that, if there be such a material as germ-plasm, it has been proved in this case to have been highly unstable. Therefore, in dealing with these and other similar facts, Weismann himself can only save his postulate of continuity by surrendering for the time being his postulate of stability[28].