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LORANDE LOSS WOODRUFF AND RH. ERDMANN 



Text figure 21 



the multiplication of niicronuclei until there are a dozen or more 

 in a cell. Although it seems clear that these represent stages 

 in the process, it is impossible from his figures to be sure that 

 many of the bodies which he interprets as niicronuclei are not 

 chromatin bodies which have arisen from the macronucleus as 

 occurs in Paramaecium aurelia. However, Popoff's paper shows 

 that he recognizes a general similarity of the so-called depression 

 phenomena and the cytological changes incident to the early 

 stages of conjugation. Our data, secured by a daily cytological 

 study of pedigreed animals, throw light upon Popoff's isolated 

 stages and indicate with considerable certainty that they are 

 stages in the sequence of normal nuclear changes in the process 

 which closely parallel conjugation both in morphological and 

 physiological Teatures. 



Gregory ('09) in a study of the life history of Tillina magna 

 points out that " . . the curve which represents the 



general vitality of the protoplasm shows the normal rhythmic 

 fluctuations observed by Woodruff," and in an analysis of the 



