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THOMPSON YATES LABORATORIES REPORT 
33 fx in the horse and ass; the breadth was the same. Laveran and Mesnil never 
observed the parasites in the blood after inoculating a pig with T. brucei, still its 
blood was very pathogenic to rats, mice, etc. ; rive to eleven days after inoculation. 
Animals naturally infected with T. lewisi succumb to inoculation with T brucei in the 
usual time. 
In this connexion, the question of the identity of Surra with Nagana is interest- 
ing. Koch 1 has observed no morphological differences between the two parasites. 
The symptoms produced in animals appear to be also identical, with the exception that 
cattle were considered to be more refractory to Surra, but Rodgers 2 has lately shown 
that in cattle in India, as also in goats and sheep the disease follows a similar char- 
acteristic course to Nagana in Africa. He points out that cattle may succumb to 
Surra, while in Africa they may not infrequently recover from Nagana. 
Rodgers 1 has also shown that Surra can be transmitted by the bites of horse 
flies (Tabanus tropicus). 
With regard to Mai de Caderas, Laveran and Mesnil' state that the parasite 
is identical with that of Nagana. It effects horses in a similar manner, but cattle 
appear to be absolutely refractory. 
Laveran and Mesnil 5 point out that the parasite of Dourine, can be easily 
distinguished from the other trypanosomes by its pathological effects on animals, and 
its morphological characteristics. Cattle, sheep, goats, are refractory. The disease 
is only transmitted during the act of coitus. The parasites are rare in the blood 
occurring for the most part in the oedema fluids. 
From the foregoing facts, it will be seen that it is impossible to identify the 
typanosome in man without inoculation experiments in the lower animals. It is 
quite reasonable to believe that the trypanosome I have described may be a known 
species modified in man ; but on the other hand, I would point out that there 
has not been a case recorded of symptoms produced by trypanosomes amongst 
natives or whites in the countries where these diseases occur, though they are 
subject to the same risk of infection ; for instance, in Africa the tsetse fly bites 
travellers, natives, and others just as much as animals. 4 I have not found any 
record of Nagana occurring in animals in the Gambia. Horses live well in 
Bathurst, and from places up the river have been sent down to other parts of 
the coast. At a place one hundred and eighty-five miles up the river, Baia, I 
observed donkeys in good condition ; but at some places on the West Coast horses 
cannot be kept. Dr. Christy informs me that he has seen trypanosomes in the 
blood of horses in Northern Nigeria ; at Jebba all horses were examined for 
trypanosomes before being bought by the Government. 
i. Reiseberichte, Berlin, 1896. 
2. Pro. Royal Society, M;iy 4, 1901. 
3. Loco. cit. 
4. See Bruce, loco. cit. 
