The meaning here appears to be twofold. For there are only two ways of explaining the phenomena of bud-variation. Either they are due to the influence of external conditions acting on the particular bud in question, or else they are due to so-called “spontaneous” changes taking place within the bud itself. Possibly it may be both, but at least it must be either. Well, in the above passage, Weismann appears to assume that it is both. For at the beginning of the passage he speaks of the “germ-plasm of the first ontogenetic stage” becoming “altered so far as to correspond with the altered structure of the individual which arises therefrom,” and he goes on to say that the alteration “may depend chiefly on the changed conditions of development”—that is, as I understand, the influence of external conditions. But at the end of the paragraph he says that “the changes which occur in the idio-plasm during the course of its growth” in the sporting bud, are due to “the varying proportions in which the ancestral idio-plasms may be contained in it.” Thus, I take it, Weismann here entertains both explanations of the phenomena in question: he appears to regard these phenomena as partly due to peculiar admixtures of ancestral idio-plasms in the bud itself (or “spontaneous” variation), but partly also to an alteration of the germ-plasm by its changed condition of development (or variation caused by external conditions). However, it is but of little consequence whether or not this is the meaning which Weismann intends to convey. For the point we are coming to is, that, whatever he intends to convey, “from the point of view” of the theory of germ-plasm, there is only _one_ interpretation possible. It is not open to Weismann (as it was to Darwin, or even to Galton,) to entertain _both_ the explanations, whether separately or in conjunction. For germ-plasm (unlike gemmules, or even stirp) must be held always and everywhere _unalterably_ stable: else the whole superstructure of Weismann’s theory of evolution falls to the ground. We cannot consent to his retaining this theory on the one hand, and, on the other, explaining bud-variation by “germ-plasm of the first ontogenetic stage” becoming altered “chiefly by changed conditions of development.” Even if it were true that “the alteration must be very slight, if not quite insignificant,” there would here be a rift in the lute, which must finally stop any further harping on the subject of Evolution. From the point of view of this theory, then, there is only one interpretation open,—viz., that a bud-variation is ultimately due to a peculiar admixture of germ-plasms in the seed from which the bud was ultimately derived. But the objections to entertaining this as even a logically possible explanation of the phenomena in all cases, is insuperable.