60 BIOLOGICAL ASPECTS OF HUMAN PROBLEMS 



perhaps thus enabling the characters newly ac- 

 quired in ontogeny to be transmitted and added in 

 the form of engrams to the germ cells. In other 

 words, the mnemic theory of development must 

 stand or fall with the proof or disproof of somatic 

 inheritance, or the inheritance of acquired characters. 



The greatest difficulty standing in the way of the 

 acceptance of the Hering-Semon theory is in finding 

 evidence that the cells of the developing body or 

 soma are telegraphically connected with the germ 

 cells. We have already seen that there is as yet no 

 unimpeachable evidence that acquired characters 

 are inherited, and it must be admitted at the pres- 

 ent time, that we have no proof of the kind of somatic 

 germ-cell telegraphy that is demanded by the mnemic 

 theory of inheritance. In plants there are proto- 

 plasmic threads which connect all parts of the organ- 

 ism; hi animals the nerve fibers radiate from the 

 nervous system to nearly every kind of cell. There 

 is, I think, a sufficient anatomical basis for the 

 Hering supposition that "all parts of the body are 

 so connected that what happens in one echoes 

 through the rest, so that from the disturbance occur- 

 ring in any part some notification, faint though it 

 may be, is conveyed to the most distant parts of the 

 body." 



Weismann looks with disfavor on the idea that 

 germinal engrams can be formed by messages sent 

 through nervous paths. He thinks the nervous 

 impulses all have the same quality except in respect 



