450 LORANDE LOSS WOODRUFF AND RH. ERDMANN 



data which we present and our interpretations of them. The 

 third micronuclear division is absent; two 'reduction' micronuclei 

 remain which are shifted into two cells. Figures 15, 16 and 39 

 show the cell division in the climax; figure 41 gives a single cell 

 which has completed that division; figure 40 shows the next 

 micronuclear division preceding the formation of the macro- 

 nuclear anlagen; figure 16, anterior cell, figures 17 through 24, 

 and figure 39, anterior cell, give the formation of the two macro- 

 nuclear anlagen and the micronuclear changes in each stage. 

 The distribution of the macronuclear anlagen is shown in figures 

 25, 42, and 43. 



C. ASCENDING PHASE 



The ascending phase of the reorganization process, which is 

 the longest of the three, extends from the formation of the macro- 

 nuclear anlagen to the restoration of the typical paramaecium 

 cell with one macronucleus and two micronuclei. It is identical 

 with the periods F and G which Maupas describes as the first 

 divisions after typical conjugation in Paramaecium aurelia ('89, 

 p. 221). 



Two micronuclear divisions occur in a very short time, half 

 the products of the second forming the two macronuclear anlagen. 

 The two untransformed micronuclei divide again and the first 

 cell division ensues. The following divisions of the cell are exactly 

 similar to typical vegetative divisions and can only be distin- 

 guished by the fact that the involution of the chromatin bodies 

 is in progress. 



The details of this period are remarkable in various ways. 

 Figures 17, 18, and 19 (pi. 2) give details of the formation of the 

 macronuclear anlagen. The chromatin bodies are omitted from 

 the drawings. These three preparations are counter-stained 

 with eosin, which, according to Calkins ('07, p. 383), stains the 

 non-chromatic parts of the micronuclei of Paramaecium cau- 

 datum. The posterior micronucleus (fig. 17) has just divided 

 and of the products of this division one remains a typical micro- 

 nucleus while the other shows the beginning of the development 

 of a micronucleus into the fundament of the macronucleus. 



