102 THE BIOLOGICAL PROBLEM OF TO-DAY 



solution of the problem may be sought. In general 

 terms, our problem is the necessary origin from an 

 egg, always of the same organism, with its manifold 

 characters, and the explanation must avoid the 

 attribution to the egg of characters foreign to its 

 nature as a cell. This is the more necessary as 

 Weismann objects to the supposition that cell- 

 division is doubling, holding that the supposition 

 allows neither an explanation, nor even the beginning 

 of an explanation, of the differences that arise among 

 cells while the differentiation of the body occurs. 

 1 Any explanation must in the first place account for 

 this differentiation/ says Weismann (Germplasm, 

 p. 224) ; ' that is to say, the diversity which always 

 exists amongst these cells and groups of cells 

 arising from the ovum must be referred to some 

 definite principle. In fact, no one could even look 

 at it as giving a partial solution of the problem, if 

 differentiation is supposed to be due to that part 

 alone of the germplasm becoming active which is 

 required for the production of the cell or organ 

 under consideration. But the higher we ascend 

 in the organic world, the more limited does the 

 power of producing the whole from separate cells 

 become, and the more do the numerous and varied 



HERBERT SPENCER : A Rejoinder to Professor Weismann. Con- 

 temp orary Review, 1893. 



Ibid. : Die Unzulangliclikeit der l NatiirZichen Zuchtwahl.' BioL 

 Centralblatt, vol. xiv. , No. 6. 



EMERY: Die JSntstehung und Ausbildung dcs Arbeiterstandes I>CL 

 den Ameisen. BioL Centralb., vol. xiv., No. 2, 1894. 



HAACKE ; Gestaltung und Vererbung (1894). 



