But as far as the transmission of effects of somatic changes is concerned, if protozoa undergo special modifications under the influence of external conditions, will not the germ-cells undergo special modification under the influence of changes in the somatoplasm which forms their immediate environment? We must never forget the close relationship between all the cells of the body, and how slight a change in the body or its surroundings may conduce to sterility or fertility. Such isolation and independence in the body, on the part of the germ-cells, is opposed to all that we know of the organic unity of the body, whose cells have arisen by the differentiation of, and division of labor between, cells primitively alike. The facts of bud-variation, of changes in the parent stock due to grafting, and others, of which Mr. Darwin has given a summary in the eleventh chapter of the first volume of his "Plants and Animals under Domestication," have never been adequately explained by Weismann in accordance with his theory. He has perhaps succeeded in parrying their force by showing that some such explanation is conceivable; they still point strongly against him. Wilson has good reason for his "steadily growing conviction that the cell is not a self-regulating mechanism in itself, that no cell is isolated, and that Weismann's fundamental proposition is false." But, granting the force of these criticisms, the question still remains, Is the special effect of use or disuse transmissible? Would the blacksmith's son have a stronger right arm? 1. The isolation and independence of the germ-cells, which Weismann postulates as opposing this, can hardly be as great as he thinks. 2. It is in his view impossible to conceive how these acquired characteristics can in any way reach and affect the germ-cells in such a manner as to reappear in the next generation. 3. All variations can be explained by his own theory without such transmission. Why then believe that acquired characteristics can in some inconceivable way affect the germ-cells so as to reappear in the next generation, as long as all the facts can be explained in a more simple and easily conceivable manner? As to his second argument, I would readily acknowledge that it is at present difficult or impossible for me to conceive how any cell can act upon another, except through the nutrient or other fluids which it can produce. But though I cannot conceive how one cell can affect another, I may be compelled to believe that it does so. And this Weismann readily acknowledges.