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THE AMEBIC AN NATURALIST 



[Vol. XLVII 



peared in 1878, in which a connection between the germ-cells of 

 different generations is supposed to exist :— and this is not the case. The 

 entirely new statement of his ideas has been influenced by those con- 

 tained in my essays which had appeared in the meanwhile. 



As a matter of fact the quotation from Jager which Weis- 

 mann repudiates actually appeared more than eight years before 

 the publication of Weismann's essays, as the quotation from 

 Kosmos, given above, clearly shows. Although Jager coined the 

 expression "Continuity of the Germ-plasm," the idea involved 

 seems to have attracted no attention until after the essays of 

 Weismann had aroused general scientific interest. 



Jager also assumed a material connection between the germ- 

 cells of different generations, 12 and, in what Weismann char- 

 acterizes as "a few casual remarks," Rauber 13 expressed a con- 

 ception which some authors interpret as the same idea. 



In the account of his exhaustive researches on the differentia- 

 tion of the reproductive ceils Xussbaum gave clear expression to 

 the doctrine of the continuity of the germ-cells, which in a strict 

 sense means that germ-eel is arise directly from one another. 

 The views held by Nussbaum 14 were in part set forth in the 

 following words: 



11 Rauber, A., ' < Formbildung und Formstorung in der Entwicklung von 

 Wirbelthieren," Morphologiache Jahrbuch, Vol. 0, 1880, p. 4. The "casual 

 remarks" are as follows: 



"Die beiden Theilstticke, deren Verbindung das neue Wesen bewirkt, 

 sind bei den hoheren Thierformen enthalten in besonderen Organen, den 

 Keimdrusen. Da aber die Keimdrusen die folgende Generation beherbergen, 



eigenen sowie der folgenden Generation. Insoweit er der Triiger seiner 

 selbst ist, stellt er eine Person im engeren Sinne dar; er ist der Personal- 

 theil der dualistischen Anlage. Die Triiger der Zukunftigen Generation, die 

 Keimdrusen, stellen dagegen den GermiiiolUn il der dualistischen Anlage dar. 



"Personal- und Germinaltheil geben aber von einem befruchteten Ei 

 aus, ein solches Ei enth&lt den Stoff mit dem Krafteplan zu der genannten 



"Nussbaum, M., "Zur Differenzierung des Geschlechts im Thierreich," 

 Archiv fiir mikroslopische Anatomie, Bd. 18, 1880, p. 112. The text of 



"Es theilt sich demgemiiss das gefurchte Ei in das Zellenmaterial des 

 Individuums und in die Zellen fur die Erhaltung der Art. In beiden 

 Theilen geht die Zellenvermehrung continuirlich weiter; nur tritt im Leibe 

 des Individuums die Arbeitstheilung hinzu, wiihrend in seinen Geschlechts- 



