THE PHYSIOLOGY OF EXERCISE. 439 



ically, we must conclude that in the struggle for existence those creat- 

 ures 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 He- 

 ring 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 circum- 

 stances in which it has lived, and that, in consequence of this, every 

 organic being imparts to the germ that separates from it a small patri- 

 mony which it has acquired in the individual life of the mother organ- 

 ism 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 repre- 

 sents 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 expres- 

 sion of an original power, appears to me to be rather a darkening than 

 an illuminating generalization. Herr Hering finds the tertium com- 

 parationis 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 con- 

 ditions, 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 ( Geddchtniss) indicates, memory is an 

 attribute only of thinking beings. Herr Hering's unconscious recollec- 

 tion 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 hazard- 

 ous, 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 per- 

 fectly incomprehensible. 



We are indeed indebted to the mechanical theory of gases for 

 more just conceptions of the minuteness and the number of molecules; 



