Trypanosoma Evansi hy Horse Flics. 



169 



membranes, and once more the results obtained in the case of surra 

 are precisely similar to those got in the researches on tsetse-fly disease 

 conducted under the Committee of the Eoyal Society. 



IV. Is the Trypanosoma sanguinis related to Surra ? 



It is pretty generally agreed that the Trypanosoma sanguinis of rats 

 is distinct, both morphologically and pathologically, from nagana and 

 surra, although in the case of the latter disease Dr. Lingard claims to 

 have produced surra in horses and other animals by inoculating this 

 organism. The incubation period, however, in his four successful 

 out of twelve experiments in horses, varied between 7 and 65 days, 

 although on the next passage it returned at once to the ordinary 

 period for surra of about 7 days. This remarkable fact, taken in 

 conjunction with his having worked in an infected area, and with 

 the proof of the possibility of flies carrying the disease, makes it 

 possible that the infection was produced by some other agency than 

 the rat's parasites. I recently inoculated a pony intravenously with 

 2 c.c. of the blood of a rat infected with the Trypanosoma sanguinis, 

 with a negative result during the 55 days it was under my observa- 

 tion, the blood being examined daily, the experiment having being 

 carried out at a time of the year when no biting flies were to be 

 found, and in a non-endemic area. It may thus be worthy of record 

 in this connection, as although but an isolated one, it is in agree- 

 ment with the results of Vandyke later. 



Another pony inoculated with a few drops of the blood of a surra 

 dog five days after the one just mentioned, developed surra on the 

 ninth day, as shown by the presence of the Trypanosoma Evansi in its 

 blood. A negative result was also obtained in the case of a dog 

 which was twice inoculated with the Trypanosoma sanguinis and 

 examined daily for 82 days. 



Eats, which had been found to harbour the Trypanosoma sanguinis, 

 were also inoculated with surra, and after the usual incubation period 

 in these animals of about four days the Trypanosoma Evansi appeared 

 in the blood, and were easily distinguished from the former parasite 

 by their much shorter and blunter ends. They increased daily until 

 in most of the cases over 50 were present in a field of a Zeiss D lens, 

 while the original rat organisms remained at about the same numbers 

 as before the inoculation with the surra blood. The two organisms, 

 therefore, appear to me to be quite distinct both morphologically and 

 pathologically. 



In every point, then, that I have so far investigated, the results 

 obtained in the case of surra closely agree with those of the Eoyal 

 Society's Committee in tsetse-fly disease, and so far as they go they 

 support the view that the two diseases are probably identical. I had 



