THE GENERAL PHYSIOLOGY OF THE PROTOZOA 211 



the merozoon which survived was not necessarily the one which contained the 

 micronucleus. Regenerated individuals multiplied for a number of genera- 

 tions, producing a culture of " amicronucleate " Paramecia. If, on the other 

 hand, a Paramecium in process of division was halved, each hah* regenerated 

 the entire body and was capable of division. These experiments indicate 

 that Paramecium contains a division- centre independent of the nuclei, and 

 that its presence is necessary for regeneration of the body. 



Prowazek (189) observed occasionally a certain power of regeneration in 

 non-nucleated fragments of Stentor, but considered it possible that extra- 

 nuclear chromatin might have been present. The same author (190) ob- 

 served abnormal regeneration, leading to monstrosities with three hinder ends, 

 in a culture of Stylonychia mytilus during a depression- period which led finally 

 to the extinction of the culture. The recent experiments of Lewin (172) on 

 Stylonychia mytilus show that, in the regeneration which follows artificial 

 mutilation, multiplication of micronuclei may occur, with the result that the 

 regenerated individual may have more micronucleithan the number typical 

 of the species or race. 



Bibliography. For references see p. 481. 



