476 LORANDE LOSS WOODRUFF AND RH. ERDMANN 



animal. From our results we would interpret this as a stage in 

 the ascending phase of the process, because he figures the four 

 macronuclear anlagen typical for Paramaecium caudatum and 

 terms them Mikronukleusderivate (see text figure 15, which is 

 a copy of Doflein's figure) . 



Finally, does the process occur in other genera of Infusoria, 

 and in other classes of Protozoa? Later in this paper we shall 

 discuss the literature relative to this point but it can be stated 

 here that while no positive evidence is extant to answer this 

 question, because pedigreed cultures involving a daily detailed 

 cytological study have not been made, nevertheless, such more 

 or less random facts as may be gleaned from various investiga- 

 tions strongly suggest, at least, that the authors are dealing with 

 comparable nuclear reorganization phenomena. 



vi. the reorganization process and its relation to 



rhyth:ms 



Earlier work on this culture has showai that there are rhythms 

 in its rate of reproduction which are not the results of environ- 

 mental variations, but which are due to some periodic internal 

 phenomena of unknown character. 



Minor fluctuations are evident in the division rate of other 

 species of Infusoria bred by the daily isolation method first 

 employed by Calkins. The fluctuations in the culture graphs 

 of Calkins on Paramaecium caudatum, Woodruff on Oxytricha 

 fallax and Gastrostyla steinii, Gregory on Tillina magna, and 

 Moody on Spathidium spathula appear to be of the same 

 character as those demonstrated in this culture. However, 

 since the authors in the study of the life history of these species 

 have not eliminated the possibility that the fluctuations in the 

 division rate are the results of environmental changes, it is im- 

 possible to state positively that the fluctuations observed by 

 them are actually 'rhythms,' though it is highly probable that 

 such is the case. 



It is important to emphasize the fact, although it is well 

 known, that relatively slight changes in culture medium or tem- 



