THE WONDERS OF LIFE 



frequent repetition of one and the same act, which is 

 closely connected with the memory of the plasm, a 

 pennanent modification is caused, either in a positive 

 or a negative sense; positively the organ is developed 

 and strengthened by exercise, negatively it is atrophied 

 or enfeebled by disuse. When this accumulation of 

 slight changes continues, the effect of adaptation goes so 

 far in time as to produce new organs by progressive 

 modification, or to cause actual organs to become useless 

 and rudimentary, and finally disappear, owing to regres- 

 sive metamorphosis. 



When we make a careful study of the simpler proc- 

 esses of habit in the lower organisms, we see that they 

 depend, like all other adaptations, on chemical changes 

 in the plasm, and that these are provoked by trophic 

 stimuli — that is to say, by external action on the metab- 

 olism. As Ostwald rightly says: "The most impor- 

 tant function of organisms is the conversion of the va- 

 rious chemical energies into each other. The chemical 

 energy that is taken into the organism as food is not 

 generally capable of being applied directly to its pur- 

 poses, but needs some further preparation. Every cell 

 is a chemical laboratory, in which the most varied re- 

 actions take place without fires and retorts. The most 

 frequently employed means in this is probably the 

 catalytic acceleration of the usable and the catalytic 

 retardation of the useless reactions. As a proof of this 

 we' have the regular presence of these enzyma in all 

 organisms." In this the greatest importance attaches 

 to memory, which iS-egard with Hering as a general 

 property of living substance, "in virtue of which certain 

 processes in the living being leave effects behind them 

 that facilitate the repetition of the processes." I agree 

 with Ostwald that "the importance of this property can- 

 not be exaggerated. In its more general forms it effects 

 adaptation and heredity, in its highest development the 



416 



