156 



FLORENCE PEEBLES. 



living less than twenty-four hours after the operation were 

 omitted from the records. By this process of elimination the 

 making of tables was greatly simplified. 



FIG. i. Diagram of vegetative cell FIG. 2. Fragment of cell from which 



showing regions of the cut for remov- the anterior end was removed. B and C, 



ing the anterior or posterior end and the cells formed from it by division in the 



dividing the cell in half. original plane. 



i. Removal of the Anterior End. In this experiment the 

 anterior end of the cell was cut off at the level indicated in Fig. i , 

 X, thus removing from one fourth to one third of the cytoplasm. 

 The small non-nucleated piece (Fig. i, A) anterior to the cut 

 usually disintegrates immediately after the operation, but in a 

 few cases it closed in, forming a spherical mass which swam about 

 rapidly for a day and then died. Such pieces never divide or 

 show any sign of growth. The removal of the end often produces 

 great disturbance in the larger nucleated piece. This is probably 

 due to the fact that the macronucleus lies so near the level of the 

 cut, and the oral groove prevents the closure of the wound. The 

 following table gives the results from eighty-three individuals. 



TABLE I. 



Thirty-four per cent, of the pieces developed new cilia at the 

 cut end and grew to the normal size before dividing, but nearly 

 fifty per cent, divided in the original plane (represented in all 

 figures by the dotted line) forming a small irregular anterior 



