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20 VitaliUj and Organization of Protoplasm. 



theory are adopted by other current views of ontogenetic evolution, the 

 exposure of their fallacy can not be deemed superfluous. 



The Continuity of Germplasm — ^Veismann. 



It is evident that in sexual reproduction the spermatozoon conveys 

 somehow more or less completely the traits of the male parent. And 

 as its head is found to consist almost entirely of nuclear substance, and 

 to originate from nuclear plasm; as, moreover, this nuclear head is 

 seen to unite during fertilization with the nucleus of the ovum under 

 specifically figured karyokinetic deployment ; it lay near to look upon the 

 nucleus as being the exclusive bearer of the germinal or reproductive sub- 

 stance. And, forming part of the nuclear material, the chromatic sub- 

 stance, by dint of its peculiarly regulated mode of fission and division, 

 quite especially ofl'ered itself in the shape of so-called chromosomes as the 

 veritable idioplasms, and was so designated by 0. Hertwig and Stras- 

 burger. 



On this carefully observed and established foundation Weismann 

 reared his ingeniously elaborated and widely celebrated theory of the 

 "continuity of the germ-plasm." The chromatic plasm is actually ob- 

 served to be continuously and directly transmitted during mitotic di- 

 vision from one germ-cell to another. This direct observation of the 

 continuity of what is taken to be germ-plasm seemed thus effectively to 

 circumvent the insurmountable difficulties in the way of conceiving how 

 a definite assortment of gemmules representing the different Idnds of 

 adult cells, and detached from the same, come to be collected in germ- 

 cells. This "wonderful" germinal representation of all kinds of phy^ 

 letically evolved cells, as autonomous beings, in one and the same ger- 

 minal receptacle, constituted for Darwin the principal phylogenetic and 

 ontogenetic riddle. He asks : "How can the use or disuse of a particu- 

 lar limb, or of the brain, affect a small aggregate of reproductive cells, 

 seated in a distant part of the body, in such a manner that the being 

 developed from these cells inherits the characters of either one or both 

 parents ?" 



Weismann answers, that no kind of functional use or disuse ever af- 

 fects the content of reproductive cells; that they exclusively reproduce 

 their own phyletically inherited potencies, regardless of what modifica- 

 tions of structure or function may have been acquired by the organism 

 during its individual life. Under this essentially different view the 

 task of accounting for the acquirement and rejiroduetion by the g^rm- 

 plasm of the peculiarities of the structures of complex adult organisms 

 was, however, only apparently facilitated. For granting that__phyletic 

 evolution has been impressed on the continuous germ-plasm, the ques- 

 tion how this germ-plasm has come to be phyletically differentiated and 

 developed, so as potentially to represenf ^'^rifl onTogen'-ticaTly to repro- 

 ^uco.the multifold structural and functional characteristics of the adult 

 organism,_this fundamental quoslinn ])rov(s lier*^ tn be not a wliit less 

 perplexing than the Lamarckian problem just (luotrd from Darwin. 



