Dr. M. Verworn's Biological Studies of Protista. 163 



Further, in a number of Polystomellce the last ten or twelve 

 chambers were removed in connexion. The chambers tlius 

 removed showed no regeneration in a fortnight, although their 

 vital phenomena were by no means extinguished. They were 

 then killed, decalcified and stained, by which means their 

 want of nuclei was demonstrated with certainty. The 

 remaining portions, on the contrary, showed the same form 

 of regeneration as was first described. 



Then some specimens were so cut up that a portion was 

 cut away from a series of chambers. The pieces removed 

 lived on, but also without any phenomena of regeneration. 

 The other portion, in which the nucleus was situated, on the 

 other hand, had deposited over all the incised chambers a 

 common, external, continuous calcareous layer, which com- 

 pletely closed the wound and showed the typical shell-struc- 

 ture (fig. 6). 



Lastly, smaller lesions were effected in a series of indivi- 

 duals, triangular notches being made with the lancet in certain 

 places, affecting only one or a few chambers. In a few days 

 these wounds also became covered with a continuous calca- 

 reous layer. 



It frequently happened that, after the removal of the 

 chambers, the protoplasm became retracted from the last open 

 chamber behind the next chamber- wall. In tlie case of the 

 other wounds also the protoplasm sometimes drew back into 

 the interior, and then the wounds did not heal. But even 

 after a new calcareous wall had been constructed on an injured 

 chamber, the protoplasm frequently drew back out of this 

 chamber, as, indeed, even in uninjured individuals the 

 youngest chamber or chambers are often quitted by the pro- 

 toplasm . 



In order to determine with still more certainty the influence 

 of the nucleus upon the regeneration of the shell, a series of 

 divisions was made in which enucleate pieces of different sizes 

 were separated. I succeeded in keeping such portions alive 

 for nearly three weeks. Even half of the protoplasmic con- 

 tents of a single chamber remained alive witiiin the fragment 

 of its shell for a fortnight, when the fragment was killed. 

 All non-nucleate fragments showed not the smallest trace of 

 new formations^ a phenomenon which stands in the fullest 

 accord with the results of Nussbaum's * and Gruber's f 



"Ueber spontane und klinstliclie Theilung von Infusorieu," in Verb. 

 naturb. Ver. preuss. Rbeinl. 1884. 



+ "Zur Pbysiologie und Biologie der Protozoen," in Ber. natiirf. Ges. 

 zuFreiburg i. B. 188G (see ' Annals,' ser. 5, vol. xvii. p. 473). 



11* 



