484 



LORANDE LOSS WOODRUFF AND RH. ERDMANN 



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19 



20 



Text figures 19 and 20 



beyond that typical for the species was substantiated by Wood- 

 ruff ('05) who observed marked macronuclear fragmentation as 

 well as a tendency to micronuclear reduplication at periods of 

 low division rate in a culture of Oxytricha fallax. The fact that 

 Woodruff was able to 'rejuvenate' the race when apparently on 

 the verge of extinction led him to state that *'we are hardly 

 justified in assuming that Protozoa, when dividing at a low rate, 

 with nuclei fragmented, etc., are exactly 'abnormal,'" and "sug- 

 gests that we are justified in regarding these changes as phases 

 in the life history of Infusoria which occur under certain con- 

 ditions after a considerable period of vegetative reproduction." 

 It now seems probable that this tentative suggestion points in 

 the right direction. The discovery of atypical conditions, chiefly 

 during the period of deepest depression and throughout the 

 month that it persisted before 'rejuvenation' occurred, would 

 seem to indicate that owing to unfavorable environmental con- 

 ditions the race of Oxytricha was in an unhealthy state which 

 resulted in a series of abortive attempts to reorganize itself, the 

 final one of which was successful. 



