66 RE GENERA TION 



others may be without nuclei. The nucleated pieces produce a new 

 membrane, and later become typical organisms, but non-nucleated 

 pieces do not form a new membrane, and soon disintegrate. Nuss- 

 baum ('84, '86) cut into pieces the ciliate infusoria, oxytricha and 

 gastrostyla. Those pieces that contained a nucleus quickly regener- 

 ated a new whole organism of smaller size, that had the power of 

 further reproduction, while the pieces that did not contain a part 

 of the nucleus showed no evidence of regeneration ; and, although 

 they continued to move about for as much as two days, they subse- 

 quently disintegrated. Gruber obtained the same result on another 

 ciliate infusorian, Stentor ccernleus. He found that, although the 

 non-nucleated pieces close over the cut-surface, and move about for 

 some time, they eventually die. He further showed that a non- 

 nucleated piece containing a portion of a new peristome in process 

 of formation will continue to develop this new peristome, although a 

 new peristome is never produced by a non-nucleated piece under 

 other circumstances. He believes that if the new peristome has 

 begun to be formed under the influence of the old nucleus, it may 

 continue its development after the piece is severed from its connection 

 with the nucleus. A non-nucleated piece containing a part of the 

 old peristome does not produce a new peristome from the old piece. 

 Gruber observed that a non-nucleated piece of amoeba behaves differ- 

 ently from a nucleated piece, and dies after a time. 



Klebs found that when certain algae are put into a solution that 

 does not seriously injure them, but causes the protoplasm to contract 

 into balls, some of these contain nuclei, others not. If, for instance, 

 threads of zygnema, or of spirogyra, are placed in a 16 per cent solu- 

 tion of sugar, the protoplasm of each cell breaks up into one or more 

 clumps, some with nuclei, others without. Both kinds may remain 

 alive for a time; some of the non-nucleated pieces may live for 

 even six weeks. The nucleated pieces surround themselves at once, 

 when returned to water, with a new cellulose wall, but the non-nucle- 

 ated pieces remain naked. The latter can, nevertheless, produce in 

 the sunlight new starch that is used up in the dark and is made anew 

 on the return to light. 1 



Balbiani ('88) found that non-nucleated pieces of cytrostomum, 

 trachelus, and protodon failed to regenerate, and Verworn ('89 and 

 '92) obtained similar results on several other protozoa. Similar 

 facts have been made out by Hofer ('89), Haberlandt and Gerassi- 

 moff ('90). Palla ('90) found that in certain cases non-nucleated 

 pieces, especially those from cells in growing regions, can produce a 

 new cell wall; while more recently Townsend ('97) has shown in 



1 In other plants, fumaria, for example, non-nucleated pieces do not seem to be able to 

 make new starch after using up that which they contain at first. 



