430 LORANDE LOSS WOODRUFF AND RH. ERDMANN 



With this theory swept away by a fact the results derived 

 from this culture stand where they stood before and demonstrate 

 that the very limited periods in which Maupas, Calkins, and 

 others observed degeneration have no significance for the ques- 

 tion as to whether degeneration and death are inevitable results 

 of reproduction without conjugation. In other words, this one 

 positive result from Woodruff's race outweighs all the negative 

 evidence derived from work on the Infusoria, and justifies the 

 statement that these organisms can live indefinitely, when sub- 

 jected to favorable environmental conditions, without conjuga- 

 tion or artificial stimulation. 



Although morphological or physiological variations which could 

 be interpreted as the result of degeneration were never observed 

 in Woodruff's race of Paramaecium, it was early noted ('08) 

 "that various nuclear changes which are not at present recog- 

 nized occur normally in the life history of Paramaecium," and 

 suggested that possibly when conjugation is prevented a reorgan- 

 ization of the nuclear apparatus within the individual cell occurs. 

 Erdmann ('08) independently reached an essentially similar view 

 from a consideration of the published data on this culture and 

 a critical study of infusorian life histories, and further, in an 

 experimental study of Amoeba diploidea ('13), suggested that a 

 relation exists between sexual phenomena and rhythms. Accord- 

 ingly the present authors have collaborated in a study of the 

 daily cytological changes of this race of Paramaecium aurelia (I) . 



As a result of our study of a large series of animals preserved 

 daily during the past half year and of specimens preserved at 

 various periods throughout the existence of this culture of Para- 

 maecium, we have discovered that the rhythms in the division 

 rate are the physiological expression of internal phenomena which 

 involve the formation of a complete new nuclear apparatus, by 

 a definite sequence of normal morphological changes which 

 simulate conjugation. This nuclear reorganization, in essence, 

 consists of a gradual disintegration and absorption of the macro- 

 nucleus in the cytoplasm. Simultaneously a multiplication of 

 the micronuclei is in progress. Certain of the resulting micro- 

 nuclei degenerate while the remaining one or two form the new 



