CHAPTER XIII 

 ENDOMIXIS 



LORANDE Loss WoODRUFF 



During recent years the attention of students of the Ciliophora has 

 been focused increasingly on macronuclear changes during the life of 

 the individual cell and the life history of the species. This has revealed 

 that the macronucleus is by no means a relatively passive agent in the 

 nuclear complex, but rather a product of micronuclear activity which 

 undergoes various radical transformations in contributing to the "somatic" 

 functions of the cell until another is provided from the same source. 



Macronuclear Reorganization 



As early as 1859, Stein noted a clear band, or Kerns pah, in the macro- 

 nuclei of hypotrichous ciliates, but chiefly within the past decade this has 



Figure 153. Stages in the progress of the reorganization bands in Aspidisca lynceus 

 from the center of the horseshoe-shaped macronucleus to its tips. (From Summers, 1935.) 



been intensively studied by several investigators who have shown that 

 Kernspalten are but a part of the regions now called reorganization 

 bands, reconstruction bands, and so forth, which have an important 

 function in the transformation of macronuclear substance at the time 

 of division (see p. 21). Thus in certain cases material visibly passes 

 from this region into the surrounding cytoplasm, as, for example, in 



