332 



LORANDE LOSS WOODRUFF 



UROSTYLA GRANDIS 



On May 4, 1920, a heavy growth of Urostyla grandis was 

 discovered in a laboratory aquarium, and during the following 

 week ten animals were isolated to form ten pedigree lines. 

 These were bred on the standard beef-extract medium which was 

 suppUed fresh daily'and inoculated with a pure culture of Colpi- 





Fig. 1 Graph of the rate of reproduction of an amicronucleate race of Oxy- 

 tricha fallax. The average daily rate of division of the lines is again averaged 

 for five-day periods. 



dium. Urostyla will survive on the bacterial flora which nor- 

 mally develops in the beef extract, but for vigorous growth some 

 small protozoan form must be supplied as food. 



Four of the pedigree lines of Urostyla proved to be micro- 

 nucleate and six, amicronucleate. Accordingly, they were not 

 suitable for the experiments planned, but were continued for 

 varying periods for further cytological study. The ten lines 

 are summarized in table 1. 



