PLATE 4 



EXPLANATION OP FIGURES 



Additional Stages 



35 Subculture IE, Line VIb, 4092d generation, December 12, 1913. Typical 

 form of macronuclear disintegration. Macronucleus small. Numerous chroma- 

 tin bodies. Three micronuclei present. 



36 Subculture IE, Line VI, 4102d generation, December 14, 1913. Typical 

 form of macronuclear disintegration. Macronucleus of typical size, practically 

 devoid of chromatin. Numerous chromatin bodies. Four reduction micronuclei ; 

 (of. figs. 11 and 12). As, text figure 4, is sister cell. 



37 Subculture IE, Line Via, 4087th generation, Decembers, 1913. An atyp- 

 ical form of macronuclear disintegration, slightly resembling the ribbon-like 

 formation characteristic of conjugation. Beginning of micronuclear reduction. 



38 Mass culture started from main Culture I, October 12, 1913. Transverse 

 section through an animal at the climax. Seven chromatin bodies; two micro- 

 nuclei in a cytoplasmic layer are visible. Stained with safranin. 



39 Mass culture started from main Culture I, October 12, 1913. The pos- 

 terior cell is in the same stage as both cells in figure 15. The anterior cell, 

 after the formation of the macronuclear anlagen, has effected one more micro- 

 nuclear division than the animal in figure 16a. The food vacuoles present 

 contain remnants of material from hay infusion medium. 



40 Subculture IE, Line Vlh, 4355th generation, April 24, 1914. Stage at the 

 end of the climax after the cell division characteristic of this period. Half the 

 products of the next micronuclear division will become the two macronuclear 

 anlagen. 



41 and 42 Subculture IE, Line VIn, 4436th and 4437th generations, June 12, 

 and 14, 1914. Cell 4436 has completed the cell division in the climax. Numerous 

 chromatin bodies and one micronucleus. The sister cell in the 4436th generation, 

 which kept the line alive, formed the macronuclear anlagen and by a division in 

 about forty-eight hours distributed these to each of the two cells of the 4437th 

 generation. One of these cells is shown in figure 42. Numerous chromatin 

 bodies, one macronuclear anlage and four micronuclei. The micronuclear divi- 

 sion indicates the quick succession of cell divisions characteristic of the ascend- 

 ing phase. 



43 Subculture IE, Line Vlq, 4437th generation, June 13, 1914. Animal after 

 the first division in the ascending phase. New macronucleus with condensed 

 chromatin. Three micronuclei. 



44 Mass culture from main Culture I. Shows ribbon-like formation of macro- 

 nucleus in a conjugating animal (cf . figs. 32 and 37) . Eight reduction micronuclei, 

 three of which are drawn. 



516 



