XX Unconscious Memory 



by ascribing to tliem a " psyche," and these co-ordinated 

 enough to satisfy their needs ; and yet they possess 

 no central organ comparable to the brain, no highly 

 specialised system for intercommunication like our nerve 

 trunks and fibres. As Oscar Hertwig says, we are as 

 ignorant of the mechanism of the development of the in- 

 dividual as we are of that of hereditary transmission of 

 acquired characters, and the absence of such mechanism 

 in either case is no reason for rejecting the proven 

 fact. 



However, the relations of germ and body just described 

 led Jager, Nussbaum, Galton, Lankester, and, above all, 

 Weismann, to the view that the germ-cells or " stirp " 

 (Galton) were in the bod}', but not of it. Indeed, in the 

 bod}^ and out of it, whether as reproductive cells set free, or 

 in the developing embrj'o, they are regarded as forming one 

 continuous homogeneit}', in contrast to the differentiation 

 of the body ; and it is to these cells, regarded as a con- 

 tinuum, that the terms stirp, germ-plasm, are especially 

 applied. Yet on this view, so eagerlj' advocated hy its 

 supporters, we have to substitute for the h5'pothesi3 of 

 memorj^ which they declare to have no real meaning here, 

 the far more fantastic h3'potheses of Weismann : by these 

 they explain the process of differentiation in the young 

 embryo into new germ and bod}' ; and in the young body 

 the differentiation of its cells, each in due time and place, 

 into the varied tissue cells and organs. Such views might 

 perhaps be acceptable if it could be shown that over each 

 cell-division there presided a wise all-guiding genie of trans- 

 cending intellect, to which Clerk-Maxwell's sorting demons 

 were mere infants. Yet these views have so enchanted 

 many distinguished biologists, that in dealing with the 

 subject they have actuaUy ignored the existence of equally 

 able workers who hesitate to share the extremest of their 

 views. The phenomenon is one well known in h}'pnotic 

 practice. So long as the non-W'eismannians deal with 

 matters outside this discussion, their existence and their 



