ically, we must conclude that in the struggle for existence those creatures prevailed which, by exercise of their natural functions, casually increased their fitness for those functions, or did this more than others, and that the beings so favored transmitted this their happy gift to their posterity for further increase. Thus originated an animal world susceptible of exercise; thus was originated natural selection itself, in the exercise of an important aid; finally, thus became the whole of life, like the individual, a self-improving machine. Herr Ewald Hering was also led to the conclusion that "even those properties of an organism may be transmitted to its posterity which it has not itself inherited, but has appropriated to itself under the particular circumstances in which it has lived, and that, in consequence of this, every organic being imparts to the germ that separates from it a small patrimony which it has acquired in the individual life of the mother organism and laid up for the grand inheritance of the whole race." The more perfectly this conception agrees with the one just unfolded, the more I am sorry that I can not follow Herr Hering when he represents the capacity of living beings to transmit acquired properties as an original power of organic matter, and explains it as a power of reproduction of the same kind with memory. To make the manifold processes on which the different kinds of exercise depend the expression of an original power, appears to me to be rather a darkening than an illuminating generalization. Herr Hering finds the tertium comparationis between the transmission of acquired bodily properties and memory in reproduction. But I see no similarity between the facile rolling-off of a definite molecular process in the ganglion-cells of the individual—which is memory—and the return in the offspring of a molecular arrangement imposed, in consequence of external conditions, upon the parent, which would be the transmission of acquired properties; and, if I did see a similarity, it would for me retire before the distinction that, as the name (Geddächtniss) indicates, memory is an attribute only of thinking beings. Herr Hering's unconscious recollection is a side-piece to the idea which men since Plato, to the injury of science, have suspected as a shaping force in the "great and little world," or to the life-force, in the face of which all the problems of physics and chemistry should lie open. Unconscious recollection is, moreover, not acceptable to me, because Herr Haeckel has eagerly appropriated it, and given it an important part in his plastidule theory.
I hold this play with groundless analogies to be the more hazardous, since, finally, it can not be strongly enough sounded that the transmission of acquired properties which we have thought of, with Darwin, Herbert Spencer, Hering, and many others, as possible and real under certain conditions, is proved, on further reflection, to be perfectly incomprehensible.
We are indeed indebted to the mechanical theory of gases for more just conceptions of the minuteness and the number of molecules;
