548 Sleeping Sickness 



The protoplasm is granular and often contains chromatin dots 

 that are ^remarkable for their size and number. There is a distinct 

 nucleus of ovoid form that is always well in advance of the centre- 

 some or blepharoplast, and not infrequently is near the center 

 of the organism. There is also a centrosome or blepharoplast, 

 which appears as a distinct, deeply staining dot near the posterior 

 blunt end and from which the flagellum appears to arise. Near 

 this a vacuole is sometimes situated. 



(2) Trypanosoma rhodesiense differs from Trypanosoma gam- 

 biense in that the nucleus is never near the center, rarely far in ad- 

 vance of the blepharoplast, and not infrequently is posterior to the 

 blepharoplast. 



Staining. — The organisms are best observed when stained with 

 one of the polychrome methylene-blue combinations — Leishman's, 

 Wright's, Jenner's, Romanowsky's, or Marino's. To stain them a 

 spread of the blood or cerebro-spinal fluid is made and treated pre- 

 cisely as though staining the blood for the differential leukocyte 

 count or for the malarial parasite. 



Cultivation. — ^Trypanosoma lewisi of the rat and Trypanosoma 

 brucei of "nagana" or "tsetse-fly" disease of Africa have been culti- 

 vated by Novy and McNeal* in mixtures composed of ordinary 

 culture agar-agar and defibrinated rabbit-blood, combined as nec- 

 essary, 1:1, 2:1, 1 : 2, or 2 : 3, etc. The actual culture was made 

 chiefly in the water of condensation collected at the bottom of 

 obliquely congealed media. 



Laveran and Mesnil found that when blood containing Try- 

 panosoma gambiense was mixed with salt solution or horse-serum, 

 the tr3rpanosomes remain alive for five or six days at the temperature 

 of the laboratory. They Hve much longer in tubes of rabbit's 

 blood and agar, sometimes as long as nineteen days, and during this 

 time many dividing forms but no rosettes were observed. But 

 subcultures failed, and eventually the original culture died out. 



Bayonf has found it easy to cultivate Trypanosoma rhodesiense 

 in Clegg's ameba-agar {q.v.) and in blood agar-agar containing 

 dextrose. The organisms thus cultivated retain their virulence for 

 rats for a long time. 



Reproduction. — Multiplication takes place by binary division, 

 the hne of cleavage being longitudinal and beginning at the posterior 

 end. The centrosome and nucleus divide, then the flagellum and 

 undulating membrane divide longitudinally, and finally the proto- 

 plasm divides, the two organisms hanging together for some time by 

 the undivided tip of the flagellum. 



In addition to this simple longitudinal fission, the trypanosomes 

 seem to possess a sexual mode of reproduction. When the well- 



* " Contributions to Medical Research dedicated to Victor Clarence Vaughan," 

 Ann Arbor, Michigan, 1903, p. 549; "Journal of Infectious Diseases," 1904, i, p. i. 

 t "Proc. Royal Society, Series B," 191 2, lxxxv, 482. 



