442 LORANDE LOSS WOODRUFF AND RH. ERDMANN 



Calkins and Cull ('07, p. 383) note that, during periods which 

 they call depressions, the typical structiu-e of the micronucleus 

 of Paramaecium caudatum is lost and it becomes abnormally 

 large with the chromatin in a loosely granular condition. It is 

 a remarkable coincidence that this occurs also in Paramaecium 

 aurelia in the descending phase of the process. 



Figure 12 (pi. 1) shows the macronucleus, which now has 

 become smaller, together with fourteen chromatin bodies free in 

 the cytoplasm, and two just leaving the macronucleus. The 

 cell possesses three micronuclei: two, lying near each other in 

 a cytoplasmic layer free from granules, are in early division 

 stages, while the third has nearly finished division. Thus the 

 cell soon would have contained six micronuclei. Though four 

 micronuclei are formed in normal vegetative division the begin- 

 ning of the 'reduction' division is distinguishable from that of 

 vegetative division because the four vegetative micronuclei are 

 usually either lying in closely associated or widely separated 

 pairs in the cell (fig. 7, pi. 1) while the 'reduction' micronuclei 

 remain clustered together in a layer of homogeneous cytoplasm. 

 Later stages showing seven and eight micronuclei are given in 

 figure 13, pi. 1, and figure 14, pi. 2, already described. Thus 

 at the end of the descending period of the reorganization process 

 the paramaecium cell possesses eight micronuclei, a shrunken 

 membrane of the old macronucleus, and numerous chromatin 

 bodies which have passed out from the macronucleus (fig. 14, 

 pi. 2). 



The important multiplication of micronuclei is not without 

 precedent in non-conjugating animals. Maupas mentions a non- 

 dividing animal with three micronuclei. Popoff ('09, p. 30) 

 describes a specimen of Paramaecium caudatum with two micro- 

 nuclei which are just preparing to divide and form four without 

 cell division ensuing. Also Kasanzeff and Calkins note the 

 multiplication of the micronuclei in Paramaecium caudatum with- 

 out cell division. Popoff states further that in Stylonychia 

 mytilus, after treatment with a medium with CO2 in solution, 

 the normal four micronuclei (p. 15) multiply until eight may be 

 present. It is unnecessary at this point to discuss the theoretical 



