74 Vitality and Organizaiion of Protoplasm. 



ity and formation of protoplasm, is operative solely in the non-nuclear 

 substance, and the nucleus itself performs only an accessory function 

 in the vitalizing and formative process, however indispensable this acces- 

 sory function may be. The nucleus can here, consequently, nowise be 

 regarded as the exclusive bearer of vital and formative efficiencies. 



In Metazoa the nuclear chromatin divides into exactly ec|ual parts, 

 while the "cells," into which it equally enters, divide into heterogeneous 

 progeny. The chromatic substance is therefore not accountable for the 

 cellular differentiations. The hypothesis of the qualitatively unequal di- 

 vision of chromatic plasm, which underlies Eoux's and Weismann's view 

 of heredity and ontogeny, and which is seemingly supported by the 

 formation of half-embryos from each of the two first blastomeres^ .«3rtiis 

 view is sufficiently disj^osed of by the repeatedly and amply confirmed 

 demonstration of the ontogenetic totipotence of the plasm of each blas- 

 tomere. As the same nucleus is here present in both cases, in the forma- 

 tion of the half-embryo, and in the formation of the whole embryo by 

 one and the same reproductive plasm, it is evident that the formative 

 efficiency resides, not in the nuclear, but in the non-nuclear plasm. This 

 is likewise proved in Morgan's experiment with the eggs of frogs, which, 

 after one of the two blastomeres had l^een killed, the living blastomere 

 formed whole embryos when the position of the egg had been reversd, 

 but half-embryos when left in position. Here also the nucleus is in both 

 cases the same, and can, therefore, have no direct influence on the form- 

 ative process. 



Di^ch showed that a normally formed embryo is produced where 

 during segmentation the nuclei of the blastomeres are by means of pres- 

 sure shifted into entirely different positions in the aggregate mass of 

 protoplasm. This likewise proves that the nucleus exerts no formative 

 influence upon ontogenetic evolution. Xon-nucleated pieces of the fer- 

 tilized blastula of Echinidse have been found to develop into plutei.. 

 This is a further striking confirmation of the passive part played by 

 the nucleus in ontogenetic evolution. Townsend found that non- 

 nucleated plasm is capable of forming in plants a cell-wall when it is 

 merely connected Avith a nucleated cell by a filament of protoplasm 

 passing through the wall of this cell. This also shows that the non- 

 nuclear plasm is the real formative agent. 



Moreover, it has to be insisted upon as essential in making way for 

 a correct interpretation of ontogenetic evolution, that even if the con- 

 tinuity and immortality of chromatic plasm as exclusive bearer of the 

 formative potency be for argument's sake, granted, then the entire adult 

 organism, in every one of its structurally differentiated parts, would 

 really consist of nothing but self-multiplied chromatic units. For so- 

 matic plasm, despite the assumed self-multiplication of its own con- 

 stituent units or biophores, would neverthelesis only serve as building 

 material, or rather only as so miich nutritive material, to the formative 

 units or biophores of the chromosomes, which would then as such con- 

 stitute the entire organism. The special group of chromatic germinal 



