668 Studies in the Theory of Descent. 



dule," Berlin, 1876. The basic idea, that heredity 

 depends upon the transference of motion, and 

 variability upon a change of this motion, com- 

 pletely corresponds with the conviction gained in 

 the province of physical science, that " all laws 

 must finally be merged in laws of motion " 

 (Helmholtz 12 ). I hold this view to be the more 

 completely justifiable although certainly not in 

 the remotest degree as- proved because I 

 formerly designated the acquired individual vari- 

 ations as the " diversion of the inherited direction 

 of development." Haeckel's hypothesis in so far 

 accomplishes more than Darwin's pangenesis, in 

 which a transference of matter, and not of a 

 species of motion peculiar to this matter, is 

 assumed. But although the germ of a mechanical 

 theory of heredity may be contained in Haeckel's 

 hypothesis, this nevertheless appears to me to be 

 somewhat remote from completely solving the 

 problem. It brings well into prominence one 

 portion of the process of inheritance ; under the 

 image of a molecular motion of the plastidule, 

 which motion is modifiable by external influences, 

 we can well understand the fact of a change 

 gradually taking place in the course of genera- 

 tions. On the other hand, the assumption of 

 consciousness in the plastidule, however ad- 

 missible philosophically although only as a 



18 "Populare wissenschaftl. Vortrage,'' vol. ii., Brunswick, 

 1871, p. 208. 



