188 Intracellular Transmission of Characters 



membrane and to regenerate into new vital individuals 

 only when they possess one or several nuclei. 39 This 

 must not be understood to mean that the nucleus is the 

 only condition. The chromatophores and the other or- 

 gans of the other protoplasts must also be present, but 

 the significance of these for growth and nutrition is of 

 such a nature that their indispensability may be regarded 

 as a matter of course. Nussbaum and Gruber have later 

 proven through extensive experiments in the division of 

 protozoa, that here too the fractional parts of the proto- 

 plasts can regenerate completely only when the nucleus, 

 at least, is not lacking. 40 



The experiments of Klebs on the culture of plas- 

 molysed cells are also important. 41 I take from them 

 what follows : If cells of Zygnema and Oedogonium are 

 plasmolysed in a 10% solution of glucose, the contents 

 of the longer cells not infrequently divide into two or 

 more pieces, which, joined at first by thin threads, later 

 separate entirely from each other. If the threads are 

 now grown in light in this solution, the contracted pro- 

 toplasts surround themselves with a new cell-wall, which 

 gradually increases in thickness. Sooner or later they 

 begin to grow and divide, and in so doing, break through 

 the old cell-membrane. But in those cells where the 

 contents are split into two or more parts, of which, of 

 course, only one can get the nucleus, only this latter part 

 forms a new cell membrane; the non-nucleated pieces 



S9 Loc. dt. p. 34. 



40 Nussbaum, Ueber die Theilbarkeit der lebenden Materie, 

 Archiv Mikr. Anatomic. 1886. Gruber, A. Ueber Kunstliche Thei- 

 lung bei Infusorien. Biol Cent. 4: 717. 1885; Ber. Naturf. Ges., 

 Freiburg i-B. 1886. 



41 Klebs, G. Ueber das Wachsthum Plasmolysirter Zellen. Bot. 

 Cent. 28: 156. 1886; Arbeiten Bot. Instituts. Tubingen. 2: 565. 1888. 



