22 ^ Vitality and Organization of Protoplasm. 



knowledge of agencies in nature that are competent to accomplish these 

 tasks demanded by the theory ? All phyletic evolution has here to be 

 immediately and exclusively wrought upon the biophores composing the 

 germ-plasm; for they are held to be the veritable life-bearers, and the 

 idioplasm they compose to be the only phyletically evolved and evolving 

 substance. 



It is therefore relevant and essential to inquire by what known, or 

 by what scientifically imaginable process the primordially equal biophores 

 of the original germ-plasm can have been so profoundly affected that 

 one set will now give rise to a liver-cell, while another set will determine 

 the formation of a nerve-cell; while, in fact, divers sets or groups of 

 biophores, all directly differentiated within the narrow confines of the 

 chromosomes, will by self -division so propagate and so evolve as event- 

 ually to constitute the multifoldly differentiated structures and execute 

 the harmonized and unified functions of the adult organism? 



The biophores of the germ-plasm can be affected only by direct nu- 

 tritive conditions. For, under Weismann's consistent theory, external 

 stimuli, acting as evolutionally modifying agents, are strictly excluded. 

 How, then can the sundry adjacent biophores composing the chro- 

 mosomes be imagined to have been so differently exposed to nutritive 

 conditions, as eventually to vary so widely, and to develop so prodigiously 

 in their respective chemical constitution and formative potencies, as is 

 here necessarily required ? No nutritive process, no germinal selection, 

 aided by ever so favored and prolonged natural selection can possibly 

 have brought about this state of things, upon which Weismann's theory 

 is grounded. 



Weismann masks this cardinal difficulty of his theory by assuming 

 that through mixture of male and female germ-plasm numberless va- 

 rieties arise, which ^by means of selection of those best suited for the 

 struggle of life^he progressive development of organic beings is brought 

 about. It is,' however, evident that in order that progressive varieties 

 can come at all into existence the biophores of the germ-plasm must 

 have themselves first varied in the direction of useful organic progress. 

 In fact, the very differentiation of male and female germ-plasm, with 

 all their distinguishing peculiarities, can be due here only to differentia- 

 tion of their respective biophores, of which the plasms are held to be 

 entirely composed. All differentiation, and therewith all variation, 

 and all progressive development, can originate only in the constitution 

 of the biophores as ultimate vital units. 



This being so. no differentiation into male and female germ-plasm 

 could have occurred had their biophores not themselves undergone such 

 differentiation. Let the respective biophores of male and female germ- 

 plasm remain at their earliest stage of differentiation unchanged from 

 generation to generation, and no new varieties could have arisen from 

 their mixture. Without varieties of biophores there can result no va- 

 rieties of organisms by mixing them. And if the biophores believed to 

 compose the germ-plnsm had failed to become tlieinselves progressively 



