72 RHODA ERDMANN AND LORANDE L. WOODRUFF 



The followinjj; tube cultures therefore were started from the 

 respective isolated slide cultures as indicated above: 



Culture 

 Y 



[Tube culture a March 20. 1914 



i Tube culture b April 1, 1914 



\ Tube culture c April 3, 1914 



I Tube culture cl April 20, 1914 



[Tube culture e April 22, 1914 



Culture /Tube culture a March 12, 1915 



Z 1 Tube culture b March 13, 1915 



Continuing the discussion of the cytological changes of the 

 reorganization piocess, fig. 18 shows an animal in the climax, 

 from Culture Y about the 137th generation, without a complete 

 macronucleus and with degenerating chromatin bodies as is 

 indicated by their elongated form. This shape of the degenerat- 

 ing bodies we have frequently mentioned in our description of the 

 climax and ascending phase of Paramaecium aurelia ('14, III, 

 pi. 2). The definitive micronucleus (fig. IS), which by three 

 subsequent divisions will form eight micronuclei from which the 

 new nuclear apparatus will be formed, is characterized by its 

 lucid appearance and is lying above the main remnant of the 

 macronucleus. This cell has a perfectly healthy appearance and 

 should be contrasted with the animal shown in figure 17, which 

 is an animal from Line III g, 202d generation, which several 

 generations later died in the process of reorganization. 



Paramaecium caudatum cells with one micronucleus and no 

 macronucleus have been observed by Calkins, KasanzefT and 

 Hertwig. Calkins '04, hg. 14, pi. 2, illustrates such an animal. 

 Abnormal animals of this character must not be confused with 

 animals undergoing the reorganization process. The cell with- 

 out a complete macronucleus (fig. 18), which we figure, is an en- 

 tirely normal animal. Its sister cells carried on the race for 

 nearly 70 generations more, some of them showing the crucial 

 formation of macronuclear anlagen as will be described in detail 

 in the next section. 



C. Ascending phase. Before the onset of the ascending phase 

 the same general cytological changes are to be observed as those 



