128 



PROTOZOOLOGY 



elimination of waste substances of the prolonged cell-division, since 

 chromatin extrusion does not take place during a few divisions sub- 

 sequent to reorganization after conjugation in Conchophthirus mytili 

 and since in Colpidium and Glaucoma, the chromatin elimination 

 appears to be the cause of high division rate and infrequency of con- 

 jugation. 



Woodruff and Erdmann (1914)^ observed that in Pararnecium 

 aurelia (Fig. 56, a) at regular intervals of about 30 days, the old 



Fig. 56. Diagram showing the endomixis in Paramecium aurelia (Wood- 

 ruff), a, normal individual; b, degeneration of macronucleus and first 

 micronuclear division; c, second micronuclear division; d, degeneration of 

 6 micronuclei; e, cell division; f, g, first and second reconstruction micro- 

 nuclear divisions; h, transformation of 2 micronuclei into 2 macronuclei; 

 i, micronuclear and cell divisions; j, typical nuclear condition is restored. 



macronucleus breaks down and disappears, while each of the two 

 micronuclei divides twice, forming eight nuclei (b, c). Of these, six 

 disintegrate. At this point the organism divides into two, each 

 daughter individual receiving one micro nucleus {d, e). This nucleus 

 soon divides twice into four, two of which develop into macronuclei 

 if-h), and the other two divide again. Here the organisms divide once 

 more by binary fission (i), each bearing cne macronucleus and two 

 micronuclei (j). This process which is "a complete periodic nuclear 

 reorganization without cell fusion in a pedigreed race of Parame- 



