But let us neglect the probability of my hypothesis, and consider merely its logical accuracy. Professor Vines says:—“The fate of the germ-plasm of the fertilized ovum is, according to Professor Weismann, to be converted in part into the somato-plasm (!) of the embryo, and in part to be stored up in the germ-cells of the embryo. This being so, how are we to conceive that the germ-plasm of the ovum can impress upon the somato-plasm (!) of the developing embryo the hereditary character of which it (the germ-plasm) is the bearer? This function cannot be discharged by that portion of the germ-plasm of the ovum which has become converted into the somato-plasm (!) of the embryo, _for the simple reason that it has ceased to be germ-plasm_, and must therefore have lost the properties characteristic of that substance. Neither can it be discharged by that portion of the germ-plasm of the ovum which is aggregated in the germ-cells of the embryo, for under these circumstances it is withdrawn from all direct relation with the developing somatic-cells. The question remains without an answer.” I believe myself to have answered this above. I do not recognize the somato-plasm of Professor Vines; my germ-plasm, or idio-plasm of the first ontogenetic grade, is not modified into the somato-plasm of Professor Vines, but into idio-plasm of the second, third, fourth, hundredth, &c. grade, and every one impresses its character on the cell containing it. It may be dullness, but I confess that this does not appear to me an “answer” to Professor Vines’ criticism. Even though “idio-plasm of the first ontogenetic grade” has to become “idio-plasm of the second, third, fourth, hundredth, &c. grade,” before in each of the grades concerned it can give origin to the somatic-cells which are distinctive of that grade, I cannot see that it makes any difference (in relation to Vines’ criticism) whether we speak of those cells as containing “somato-plasm,” or as containing “somatic idio-plasm” of such and such a grade, _plus_ “cytoplasm.” For whether we thus follow Weismann’s earlier terminology or his later, we are so far speaking about exactly the same thing, namely, the transformation of “germ-plasm” into all the constituent cells of the “soma.” The difficulty is, in Vines’ words above cited, “to conceive that the germ-plasm of the ovum can impress upon the somato-plasm of the developing embryo the hereditary characters of which it (the germ-plasm) is the bearer”; and Weismann says that this difficulty, which he acknowledges, can now be answered by substituting for his original statement that “germ-plasm” becomes changed into “somato-plasm,” the statement that it is “idio-plasm” _derived_ from “germ-plasm” which thus “impresses its character on the cell containing it.” But, “as a matter of logical accuracy,” there is surely here a distinction without a difference. For what is the difference between saying that germ-plasm “impresses” its character