TSETSE DISEASE IN MAMMALS. 167 



some animals, such as the rabbit, the haimatozoa are as a general 

 rule very scarce or absent during the greater part of the course of 

 the disease. In most animals the parasites appear intermittently for 

 one or more days, and then disappear for a time, again to reappear. 



The distribution of the disease is rather widely spread ; besides 

 South and East Africa it occurs on the Congo ; the fly itself is 

 found up to the Niger on the West, and from the accounts re- 

 ceived of the way transport animals died in Lugard's expedition, 

 it is more than probable that the disease is prevalent there. 



A French observer (Rouget) has described a parasite which 

 seems to be the same in an animal (horse) at a remount depot in 

 Algeria ; the source of infection in this case was not known. In 

 India there is a disease affecting horses, &c. known by the name of 

 Surra. From the descriptions of the Surra parasite and its patho- 

 logical effects, it appears to be identical in all respects with that of 

 N'gana or Tsetse. Surra appears to be widely spread over India 

 in localised areas. In former years and still in certain districts it 

 is supposed to be connected with the bite of a blood-sucking fly ; 

 but the matter is not yet worked out. 



In England and Europe generally a somewhat similar parasite 

 is found in the blood of wild rats. It differs slightly in its appear- 

 ance under the microscope from that of N'gana. It does not 

 affect the health of the rat to any appreciable extent ; moreover 

 the attempts to inoculate dogs, guineapigs, &c. have all proved 

 negative. 



So far we have no means of curing the disease when it has once 

 begun, nor have we any means of preventive inoculation or salting. 

 Some drugs like arsenic help to prolong the life of the animals, but 

 the end is always fatal. Prof. Cossar Ewart has with the true 

 scientific spirit allowed certain of his valuable zebra hybrids to be 

 inoculated with the tsetse disease in order to see whether they will 

 shew a degree of refractoriness which the zebra must possess, in 

 that it is capable of living in the fly infested districts. It is too 

 early to make any statement with regard to these animals, since 

 they have only been recently inoculated ; they have all shown signs 

 of illness and the parasite has been found in their blood ; whether 

 they recover eventually must be left to the future to decided 



Mr Sclater asked whether the parasite itself was found in the 

 blood of wild animals, and Mr Stiles asked whether the disease was 

 carried by other biting flies ; the latter also made some remarks 

 concerning the Texas fever of cattle, which is communicated b}' 

 means of ticks. A further question was as to whether man was 

 refractory. 



In reply Mr Durham said that the experiments of Bruce had 

 shown that certain of the wild animals in the fly districts harboured 

 the parasite of tsetse disease. This had been shown by inoculation 



^ These all succumbed to the disease about 8 weeks after inoculation. 



