MORPHOLOGY AND LIFE HISTORY OF POLYTO- 

 MELLA CITRI SP. NOV. 



J. McA. KATER, 

 UNIVERSITY OF CALIFORNIA AND PRINCETON UNIVERSITY. 



The organism dealt with in this paper was first found in 

 Berkeley, California, during January, 1924, in a culture medium 

 for Euglena gracilis made after Zumstein \vhich contained the 

 following parts: peptone .5, citric acid .2, grape sugar .5, 

 MgSO 4 -7H 2 O .02, KH 2 PO 4 .05, water 100. In September, 1924, 

 a culture was shipped to me in New Jersey, from Berkeley and the 

 cultures made from this material are still in good condition. 



A little observation showed that this flagellate reproduces very 

 rapidly during the active stage and also that an abundance of 

 resting forms are periodically present. These facts seemed to 

 indicate possibilities for studying the life history. Since no 

 previous account of this organism has appeared, the name 

 Polytomella citri is proposed for it. 



I wish to thank Professor C. A. Kofoid for the many courtesies 

 extended to me while working in his laboratory, Professor E. 

 Newton Harvey for many valuable suggestions, and Professor E. 

 G. Conklin for his constant guidance and advice. 



METHODS. 



Polytomella citri thrives on the medium mentioned above, but 

 it does not make a lasting culture, two weeks usually being the 

 limit. The best results were obtained from uncooked timothy 

 hay in distilled water, to which a little sugar was occasionally 

 added. An old culture can easily be renewed by dilution with 

 distilled water. Successful cultures can be made on media with 

 Ph value ranging from 3.5 to 9. The P h of old hay cultures is 

 always around 5.5 which seems to be the ideal value for this 

 protozoan. On several occasions fresh cultures were placed in a 

 refrigerator. After remaining there for two months the jars were 

 fairly teeming with Polytomella. 



213 



