62 RHODA ERDMANN AND LORANDE L. WOODRUFF 



III. THE CYTOLOGICAL PHENOMENA OF THE REORGANIZATION 

 PROCESS IN PARAMAECIUM CAUDATUM 



The complete reorganization process without cell fusion which 

 occurs in Paramaecium caudatum, as in Paramaecium aurelia, 

 synchronously with the rhythms, presents essentially the same 

 fundamental cytological features as those we have described in 

 the latter species ('14, III, pp. 436-473). 



We shall, therefore, present merely a general summary of the 

 phenomenon in Paramaecium caudatum and point out the 

 differences which could be traced in the morphological features. 

 In accordance with our previous investigation we term the three 



Rhythm Ryhthm 



Text fig. 1 Diagram illustrating the relation of the reorganization process 

 to rhythms. (Woodruff and Erdmann, '14, III.) 



phases into which the reorganization process fendomixis) natu- 

 rally resolves itself as descending phase, climax and ascending 

 phase (text figure 1). 



A. The descending phase. The micronucleus of a typical 

 Paramaecium caudatum which is not undergoing the reorgani- 

 zation process or normal vegetative division is situated in a slight 

 depression of the macronucleus. Text-figure 2 (p. 63) shows 

 an animal shortly after a typical vegetative division in which 

 the micronucleus has not yet reached its accustomed posi- 

 tion. The structure of the resting micronucleus between two 

 vegetative cell divisions is shown in figure 1, p. 85. The posi- 

 tion of the micronucleus in figure 2 has not changed but its 



