444 LORANDE LOSS WOODRUFF AND RH. ERDMANN 



whether one or two of the reduction micronuclei remained and 

 formed immediately without a further division the stationary 

 and migratory nucleus, but in his final publication ('89, p. 31) 

 he states definitely that seven reduction micronuclei degenerate 

 but his figures do not absolutely prove this point (fig. 6, pi. 1 ; 

 fig. 24, pi. 4). A micronucleus remains which is the source of 

 the new micronuclear and macronuclear apparatus. Maupas 

 ('89, p. 219) stated earlier than Hertwig that ''Sept d'entre 

 eux vont, en effet, passer a Tetat de corpuscles de rebut et dis- 

 paraitre en se resorbant. Un seul persistera et continuera revolu- 

 tion fecondatrice," but as already mentioned, he does not give 

 cytological details so that a perfect description of the degener- 

 ation of the micronuclei in Paramaecium aurelia does not exist. 

 It is easier to trace the degenerating micronuclei in conjugating 

 animals because there the ribbon-like formation of the macro- 

 nucleus is still intact (fig. 44, pi. 4). Many chromatin bodies 

 are not free in the cell and consequently cannot be mistaken 

 for degenerating micronuclei. Thus each tiny homogeneous gran- 

 ule in the cytoplasm can be identified as a micronuclear remnant, 

 whereas in the reorganization process unconnected chromatin 

 bodies are scattered freely in the cell and minute homogeneous 

 granules intermingled with them may or may not be identified 

 as degenerating micronuclei. However, certain bodies which 

 have been observed we are inclined to interpret as micronuclear 

 remnants. These will be indicated in the description of the 

 plates. 



The reorganization process proceeds in two different ways, 

 as shown by the animals which were preserved at the climax, 

 depending upon whether or not a cell division takes place at this 

 period. The usual method is for a cell division to occur. In 

 the cell which possesses no macronucleus the chromatin bodies 

 change their shape, becoming more and more elliptical while 

 each granule begins to migrate to the surface so that the bodies 

 appear hollow. The one remaining micronucleus is large. Fig- 

 ure 15 (pi. 2) shows such cells which have just completed the 

 division at the clitnax. Each has one micronucleus while the 

 anterior cell has eight and the posterior twelve chromatin bodies. 



