REGENERATION OF PLEUROTRICHA. 



171 



In experiments 31, 32, 33 and 57 the animals were killed from 

 38 minutes to 3 hours and 30 minutes after merotomy. All of 

 these, except experiment 31, were mid-body cuts and it is reason- 

 able to assume that the condition found is normal, the macro- 

 nucleus and the micronucleus having not yet divided, or being 

 cells of the uninucleate variety which were also found in control 



TABLE I. 



ANTERIOR-END CUTS. 



cultures of this animal. In experiment 57 the micronucleus is in 

 mitosis and the cell appears normal. 



In experiment 22, also a mid-body cut, I hour and 10 minutes 

 after operation, there are two micronuclei in mitosis. The 

 nucleus is single, swollen and enlarged, as if ready to divide. 

 The most plausible explanation of the condition found here is 

 that the cell originally had two macronuclei and three micro- 

 nuclei, as was found in certain animals taken from culture. 



TABLE II. 



POSTERIOR-END CUTS. 



When merotomy was performed the animal was separated in 

 two merozoa, one of which had a single macronucleus and a 

 single micronucleus; the other merozoon which was saved and 

 which regenerated had a single macronucleus and two micronuclei. 



