THE CULTIVATION OF TRYPANOSOMA BRUCEI. 



271 



The difference between the organisms grown upon the veal blood agar 

 minus the white blood cell layer and upon the dialyzed dilute serum or in- 

 inactivated serum agar is in the size of globules, being smaller on the former 

 medium. 



The organisms grown upon the improved medium differ from the blood 

 type because of the presence of small globules; the position of the centrosome; 

 and the less conspicuous undulating membrane. 



The blood of rats in the early stages of Nagana, showing about twenty- 

 five trypanosomes per field is best suited for isolation work. Infected guinea- 

 pig blood is not desirable for this work. 



The best results are obtained when blood is used in a ratio of 2 to 1 of 

 agar and ordinary aerobic conditions are resorted to. 



To perpetuate the growth transplants should be made weekly by means of 

 a capillary pipette. Trypanosoma Brucei and Lewisi do not require the 

 presence of hemoglobin for their existence. 



The characteristic rosette formation of trypanosoma Brucei and Lewisi 

 serves as a means of differentiation. 



Since the cultures are pathogenic for rats and guinea-pigs the positive 

 causal relation of the trypanosome to the disease nagana can be demonstrated 

 by Koch's requirements. 



After obtaining such excellent results with trypanosoma Brucei this med- 

 ium seems especially promising for the cultivation of other pathogenic 

 forms. 



CHART 1 



Showing the Per Cent of Positive Results on Various Media 



