1911.] Agent in a Case of Human Trypanosomiasis. 159 



observed in the blood of the monkey was vacuolated in a remarkable manner, 

 sometimes as many as five or six large clear vacuoles were seen in a single 

 trypanosome (figs. 3, 4, 5, 7, and 9). In many of the parasites the cytoplasm 

 contained large, coarse granules. The posterior extremity of many of the 

 parasites — especially those in which the nucleus was situated posteriorly — 

 presented a blunt, " cut away " appearance. Parasites similar to those 

 described by Stephens and Fantham as " snout " forms were likewise 

 observed, but they did not appear to us to be a prominent feature. After 

 finding these posterior nuclear forms in the blood of the rabbit and monkey, 

 we re-examined carefully the slide of the blood of the patient himself, made 

 on August 31, at a time when the parasites were numerous. A prolonged 

 search failed to reveal the presence of any typical posterior nuclear forms, 

 but several dividing forms were seen, in which one of the nuclei was 

 situated close to the blepharoplast (figs. 16 and 17). 



Pathogenicity. — Unfortunately, absence of laboratory animals prevented 

 the investigation of this point. The three animals (rabbit, monkey, and 

 a goat) inoculated with the strain by one of us (H. S. S.) in Nyasaland were 

 all easily infected. 



Rabbit. — Inoculated subcutaneously with blood from the patient. The 

 temperature rose on the sixth day to 105° F., and parasites were found in the 

 blood in small numbers. The animal died on the 27th day. During the 

 last six days trypanosomes were present in considerable numbers. The 

 symptoms observed were those usually found in rabbits suffering from 

 trypanosomiasis, viz., anaemia, emaciation, oedema of the face and ears, and 

 purulent discharge from the nose and eyes. 



Monkey. — Inoculated from the rabbit. Parasites found in the blood on 

 the seventh day. During the next week trypanosomes were present in 

 considerable numbers, but later they were scanty. The animal was still 

 alive on the 36th day, but was very anaemic and emaciated. There was 

 distinct auto-agglutination of the red blood cells. 



Goat. — Inoculated from the rabbit. Trypanosomes found in the peripheral 

 blood on the 15th day and on frequent occasions, but always in small 

 numbers, until the death of the animal, which occurred on the 28th day. 

 The symptoms noted were anaemia, wasting, and cedematous swelling of face. 

 The rapidity of the course which the disease ran in this animal is worthy 

 of remark and is in accordance with the observations of one of us working 

 with the parasite obtained from a case of trypanosomiasis infected in the 

 Luangwa Valley.* 



Conclusions. — As a result of our observations we are of opinion that the 

 * Yorke, W., loc. cit. 



