388 SPECIFIC MICRO-ORGANISMS 



Trypanosoma Equinum. Elmassian in 1901 observed this 

 organism in the blood of horses suffering from Mai de Caderas 

 in South America. It possesses a very minute blepharoplast, a 

 morphological character which distinguishes it from most other 

 trypanosomes. Small laboratory animals are susceptible. 



Several other species of trypanosomes have been described, 

 which cause fatal diseases in quadrupeds. Most of these have 

 been found in Africa. 



Trypanosoma Gambiense. Button and Todd in 1901 ob- 

 served this organism in the blood of an Englishman in Gambia. 

 The parasite had been previously seen by Forde. The disease, 

 which resulted in death after two years, was called trypansoma 

 fever. Castellani in 1903 observed trypanosomes in the cerebro- 

 spinal fluid of patients suffering from sleeping sickness in Uganda. 

 This organism is now known to be the same as the Tr . Gambiense 

 of Button, and sleeping sickness is recognized as the terminal 

 stage of trypanosoma fever. 



Tr. gambiense is very similar in form to Tr. brucei but the 

 posterior end is on the average somewhat more pointed. The 

 length varies between 15 to 30^ and the width from i to 3/z. The 

 significance of the different forms found in the blood is not defi- 

 nitely known. Multiplication takes place in the same way as 

 in Tr. brucei. In the tsetse fly, Glossina palpalis, the trypano- 

 somes slowly disintegrate and disappear during the first four days 

 after the infected blood is ingested, and in most of the flies this 

 results in extermination of the trypanosomes. In 5 to 10 per 

 cent of the flies the parasites are not completely destroyed, but 

 the early diminution in their number is followed by an abundant 

 multiplication of the trypanosomes in the stomach and intestine of 

 the insect. After 18 to 53 days these flies become capable of 

 infecting new animals by their bite and remain infectious for a 

 very long time. The parasites are found in the salivary glands 1 

 when the fly becomes capable of causing the disease. A great 



1 Bruce, Hamerton, Bateman and Mackie: Proc. Royal Soc., 1911, Ser. B, 

 Vol. LXXXIII, pp. 338-344; PP. 345-348; pp. 513-527- 



