179 



Altogether 1,069 Glossbm were fed once in groups of 30 to 163 

 on eight clean dogs and two monkeys, and six of the animals 

 ■showed trj'panosomes of tlie dimorpliic type witli nuclei at the 

 posterior end, after an incubation of from four io six days. 



The high percentage of infective flies was also shown by blood 

 smears of domestic animals (dogs and goat) in the Hy area. 



The trypanosomes from the antelopes and from the naturally 

 injected domestic animals closely agree with each other and with 

 T. rhodesiense, both morphologically and as regards pathogenicity. 

 If the views of Kinghorn and Yorke were endorsed, this would 

 mean that 162 per cent, of the big game and the same relative 

 number of domestic animals would be reservoirs of human sleep- 

 ing sickness. 



The author's experiments, however, show that this opinion is 

 untenable. Glossina morsitaiu reared from the pupae were fed for 

 the first four days on a monkey heavily infected with trypano- 

 somes from antelopes, after a day's fast they were then fed 

 consecutively on four goats (0th-12th, 13th-16th, 17th-19th and 

 20th-22nd day), on a monkey (23rd-25th day), on two dogs (26th- 

 2Tth day), on the author (28tli-32nd dav), on a monkev (33rd- 

 35th day), and on two dogs (36th-40th, 4ist-44th day), the first 

 three goats remained in good health ; the fourth goat sulfered 

 from trypanosomiasis and died after 20 days, the monkey died 

 after 25 days; the two dogs showed blindness and keratitis and 

 died after 19 and 20 days respectively; the author remained in 

 good health ; the monkey died after 14 days' illness ; the last two 

 dogs died after eight and 21 days. With the exception of that of 

 the author, the blood of all the animals showed typical trypano- 

 somes with posterior nuclei. 



A similar experiment was made with the following sequence of 

 subjects consecutively inoculated by flies : monkey, goat, dog, 

 goat, five dogs, the author, two dogs, with identical results 

 regarding the immunity of man. 



In a third experiment the author injected the Mood of a dog 

 badly infected with trypanosomes by natural means, in quantities 

 varying between 0'25 and 2 cc, subcutaneously into monkey, 

 three dogs, goat, two rats and himself (2 cc). All the animals 

 after a period of incubation of three days showed severe trypano- 

 somiasis and died in from 12 days (monkey) to 22 days (rat). The 

 author remained absolutely and permanently well. 



The big game trypanosomes, therefore, in spite of being 

 apparently identical with T . rJiodesiense, must be referred to T . 

 hrucei, especially in view of the recent results of Wenyon, Black- 

 lock, Kleine and Fischer. 



In order to settle the question regarding the infectivity of T. 

 hrueei for man, the author injected subcutaneously altogetlier 90 

 cc. of his blood, a fortnight after inoculating himself with the 

 blood of the dog in the previous experiment, into a monkey and 

 seven dogs. The animals remained perfectly well, so tliat lie 

 regards it as certain that T. hrucei does not find conditions 

 favourable to its existence in liuman beings. 



