3i6 



Scientific Proceedings (116). 



original species completely supplanted by another. Cultures of 

 anaerobes require exceptional care to avoid contamination and 

 subsequent loss of identity; no culture can be accepted upon its 

 face value. 



165 (1747) 



The variation in the size of trypanosoma 

 brucei according to the host. 



By T. D. BECKWITH and W. W. REICH. 



[From the Department of Bacteriology and Experimental Pathology, 

 University of California.] 



It has been stated by observers that a certain species of 

 trypanosome may show differences in size according to the host 

 infected. An examination of the literature however reveals 

 much divergence of opinion concerning this matter. In addition 

 such statements as appear are very fragmentary. The technique 

 upon which some of them are based moreover leaves much to be 

 desired. 



Plimmer and Bradford 1 (1898) quoted by Castellani and 

 Chalmers remark that the length of Trypanosoma brucei is con- 

 stant for a given animal but varies in different hosts, being be- 

 tween 26 and 27 micra in rats, mice, guinea pigs, rabbits and dogs. 

 Kanthack, Durham and Blandford 2 state that the Nagana para- 

 sites vary considerably both in size and in form. Bruce, Hamerton 

 and Bateman 3 come to the conclusion that Trypanosoma brucei 

 varies from 10 to 16 micra in length in the rat with an average of 

 13.0 while in guinea pigs the limits are 8 to 16 micra with the 

 average 12.5. Laveran and Mesnil 4 claim that their own work 

 which included parasites from a large range of mammals shows no 

 manifest variation in size of the organism. 



A culture of Trypanosoma brucei was obtained from Dr. F. G. 

 Novy at the University of Michigan. Immediately upon re- 



•Plimmer and Bradford, quoted from Castellani and Chalmers, "Manual of 

 Tropical Medicine," 3d edition, 1920. 



'Kanthack, Durham and Blandford, Proc. Roy. Soc. London, 1908, lxiv, 100. 

 'Bruce. Hamerton and Bateman, Proc. Roy. Soc. London, 1909, Ixxxi, 14. 

 4 Laveran and Mesnil, " Trypanosomcs et Trypanosomiases," 1912. 



