ON VARIATIONS. 357 



blance. Thus lie concluded that we are almost justified 

 in reserving our belief that the body cells can react 

 on the sexual elements, i. e., that acquired characters 

 can be inherited; but he himself proposed to accept 

 the supposition of their being faintly heritable. More 

 recently, Cope* has embodied the idea in his " Theory 

 of Diplogenesis." Thus he says, " Now, since these 

 somatic cells develop the modifications which constitute 

 evolution in their subsequent growth into organs, there 

 is no reason why the reproductive cells which experi- 

 enced similar influences should not develop similar 

 characters, so soon as they also are prepared to grow 

 into organs. . . The effects of use and disuse are two- 

 fold, viz.: the effect on the soma, and the effect on the 

 germ-plasm. . . The character must be potentially ac- 

 quired by the germ-plasma, as well as actually by the 

 soma." However, when Cope begins to briefly expand 

 his theory, he seems to me to drift into improbable 

 and unverifiable speculations. Thus he imagines that 

 the transmission of external influences is primarily 

 through the nervous system perhaps through the 

 organisation of some peculiar mode of motion and 

 secondarily through nutrition. 



In order to account for the numerous instances of 

 the cumulative effects of changed conditions of life, it 

 seems, therefore, that we may assume with consider- 

 able probability and reason that the germ-plasm is di- 

 rectly affected as well as the body tissues. These ap- 

 parent instances of the inheritance of acquired char- 

 acters are in reality, therefore, nothing of the kind, but 

 are due to the germ-plasm reacting to change of en- 

 * Amer. Naturalist, xxiii. p. 1058, 1889. 



