180 THE MICHIGAN ACADEMY OF SCIENCE. 



ON THE FILTRATION OF TRYPANOSOMES. 



BY F. G. NOVY AND WARD J, MACNEAL. 



This paper will likewise appear in extenso elsewhere and for that 

 reason only an abstract is here given. 



The presence in cultures of Tr. lewisi of actively motile, minute forms, 

 ranging from two to five microns in length, suggested the possibility of 

 passing the organism through a Berkefeld filter. Of nine experiments 

 made with cultures of this organism three were positive, five were nega- 

 tive, and one was uncertain since the control animal failed to develop 

 an infection. Similar experiments with cultures of Tr. hrucci and with 

 suspensions of the organs of animals infected with the latter gave nega- 

 tive results. It would seem as if some ''filterable" diseases may be due 

 to organisms which themselves are so large as to be unable to traverse 

 a filter, but which, under certain conditions, will give rise to a minute 

 stage which will pass through. 

 F. G. NovY, Sc-. D., M.D., 



Professor of Bacteriology. 

 Ward J. MacNeal, Ph.D., 



Fellow of the Rockefeller Institute for Medical Research. 

 Hygienic Laboratory, University of Michigan, 

 Ann Arbor. 



