PERIODIC REORGANIZATION IN PARAMAECIUM 453 



jugation by the fact that chromatin ribbons are not formed. 

 There is no evidence that the chromatin bodies are ejected from 

 the cell or that the remnants fuse with the new macronucleus. 

 After the reorganization process the totally dissolved material 

 of the old macronucleus probably remains, at least temporarily, 

 in a changed chemical form in the cell. 



From our studies of conjugation in animals derived from the 

 main culture of the pedigreed race of Paramaecium aurelia we 

 can show clearly that the first division after conjugation dis- 

 tributes to each cell two micronuclei and one macronuclear 

 anlage (fig. 33, pi. 3). There is no degeneration of nuclear mate- 

 rial as Maupas ('89, p. 204) and Klitzke ('14, p. 8) have described 

 in Paramaecium caudatum. Maupas as well as Klitzke state 

 that eight micronuclei are formed from the syncaryon by two 

 mitoses quickly following each other, four of the resulting micro- 

 nuclei forming the macronuclear anlagen, three degenerating and 

 one remaining as the definitive micronucleus of the reorganized 

 cell. By two cell divisions, accompanied by divisions of the 

 micronuclei, the typical vegetative stage in Paramaecium cau- 

 datum is restored. However, Calkins and Cull ('07, p. 387) 

 do not mention a degeneration of nuclear material in this stage 

 but state that four of the eight micronuclei are transformed into 

 macronuclear anlagen and, by two cell divisions without division 

 of the micronuclei, four typical vegetative animals result. Doflein 

 in his account of Paramaecium putrinum gives the same inter- 

 pretation as Maupas and Klitzke, i.e., three micronuclei degen- 

 erate and the four potential macronuclear anlagen are distributed 

 by two cell divisions to four animals. Hamburger ('04, p. 223) 

 states that in Paramaecium bursaria two micronuclei and two 

 macronuclei are formed which are distributed in one of the two 

 following ways to the sister cells which arise: either one micro- 

 nucleus and one macronuclear anlage pass to each new cell; or 

 one macronuclear anlage and one micronucleus (the product of 

 an additional micronuclear division) pass to one sister cell, while 

 one macronuclear anlage and the other micronucleus (resulting 

 from the extra micronuclear division) passes to the other sister 

 cell. The normal vegetative state of Paramaecium bursaria, 



