i6o 



FLORENCE PEEBLES. 



from the small piece (C). Finally the chain divided posteriorly 

 into a series of normal individuals (TV) leaving anteriorly one 

 double cell (>). On the seventh day this monster was killed 

 and stained. Three mouths, two vacuoles, and only one nucleus 

 were present. 



. j. The third monster (Fig. 5) formed directly from the 

 small anterior piece (C) without dividing. 

 The piece grew rapidly for three days 

 developing processes resembling budding 

 individuals but none were thrown off. At 

 the end of the third day the mass (m) was 

 killed. Again only one nucleus was found 

 but three mouths and four vacuoles were 

 present. 



Such cases as these demonstrate that 

 there is great disturbance produced through 

 the removal of some of the cytoplasm of a 

 vegetative cell. The small piece (Fig. 5, 

 C) contained all of the nuclear material for 

 a normal cell, but less than half of the 

 protoplasm required. Before the cell-body 

 has attained its full growth the nucleus is 

 ready to divide, and in turn when the 

 _ cytoplasm is ready to divide the nucleus is 

 not. This condition of affairs produces a 

 FIG. 5. Diagram show- complete loss of balance in the mechanism 

 ing the formation of a of division and the result is that i rre gular 

 monster from a small cell 



cells and monsters are formed and the cell 



without division. 



rarely ever regains its normal condition. 



D. The Effect upon Cells Cut During Division. 



For these experiments Paramecia were selected which were 

 in the early stages of fission, at a time when the nucleus was 

 elongated and the body slightly constricted (Fig. 6). 



Experiment i. When the cell is cut in half through the plane 

 of division (Fig. 6, Y] both cytoplasm and nucleus are divided 

 equally. The experiment is a comparatively simple one and is 

 usually successful, both halves living and forming normal races. 



