Page:George Archdall Reid 1896 The present evolution of man.djvu/82



à priori grounds we must conclude therefore, that acquired variations are not transmissible, but here again I must guard myself against misconception. In the last analysis all inborn variations must of course be acquired variations. For, eliminating the effects of conjugation, since the child varies somewhat from the parent, the constitution of the germ cell, whence the child was derived, must also have varied somewhat from the constitution of the germ cell whence the parent was derived, and this variation can only have arisen as the effect of some external cause or causes. By inborn variations are therefore meant such variations in the organism as result from changes in the constitution of the germ cell whence it is derived, which changes in the constitution of the germ cell may, for instance, be produced by such alterations in the nutritive fluids as are caused by exercising the arm muscles. What is denied is, that such changes in the nutritive fluids as the above, usually produce changes of such a kind in the constitution of the germ cell as result, after conjugation and proliferation, in variations in the new organism similar to those variations in the parent organism, which resulted from that exercise which produced the alteration in the nutritive fluids. In other words, though acquired variations may so alter the nutrient fluids as to cause a secondary alteration in the constitution of the germ cell, which in turn may cause it to