68 THE ANIMAL PARASITES OF MAN 



from " stallion's disease " (dourine). In 1894 Bruce found similar forms (T. brucei] in 

 the blood of South African mammals suffering from " nagana," and in consequence 

 attention was drawn to the part which the much dreaded tsetse-fly played in 

 the transmission of "nagana." In 1901 Elmassian discovered trypanosomes in 

 the blood of horses that were stricken with " mal de caderas," which is very 

 common in the Argentine. The disease in cattle named "galziekte" (gall- 

 sickness), occurring in the Transvaal, was also at one time attributed to 

 a trypanosome remarkable for its great size, and like some other species, bearing 

 the name of its discoverer (7". theilert). 



The study of the species hitherto known has been carried on partly by the 

 above mentioned authors and in part by others, e.g., Rabinowitsch and Kempner, 

 Laveran and Mesnil, Wasiliewski, Senn. It was greatly advanced by the method 

 of double staining (with alkaline methylene blue and eosin) introduced by 

 Romanowsky (1891) and elaborated by Ziemann, Leishman, Giemsa and others. 

 By this means the presence of a terminal flagellum and of an undulating membrane 

 at the side of the flattened and extended body was demonstrated. Laveran and 

 Mesnil (1901) discovered allied flagellates in the blood of the fish, Scardinius 

 erythrophthalmus. These flagellates, now placed in the genus Trypanoplasma, had 

 a second free flagellum in addition to the one bordering the undulating membrane. 

 Trypanoplasms have since been found in both freshwater and marine fishes. The 

 transmission of trypanoplasms of freshwater fishes is effected by leeches. Trypano- 

 plasma varium from Cobitis is transmitted by Hemidepsis marginata according to 

 Leger, while the Trypanoplasmata of Cyprinus carpio and Abramis brama reach 

 new hosts by the agency of Piscicola according to Keysselitz. 



Another ally of the Trypanosomidae, Trypanophis, lives in the coelenteric 

 cavity of Siphonophores. It has also an extra terminal flagellum (Poche, 

 Keysselitz). \Trypanoplasma and Trypanophis belong to the Bodonidce, see p. 63]. 



Finally it was shown that Trypanosomes occurred in human beings. Although 

 Nepveu's early report of trypanosomes in the blood of malarial patients may be 

 doubtful, subsequent researches by Forde and Button demonstrated trypanosomes 

 (fig. 28) in the blood of a European, apparently suffering from malaria, living in the 

 Gambia. Button (1902) called the human trypanosome, T. gambiense. The expedi- 

 tion despatched by the Liverpool School of Tropical Medicine (1902) to Senegambia 

 found trypanosome infections in six cases among a thousand inhabitants examined. 



About the same time attention was devoted to the disease of West African 

 negroes known for a century as " sleeping sickness." Castellani (1903) was the 

 first to succeed in demonstrating the presence of trypanosomes (at first called 

 T. ugandense] in centrifugalized cerebro-spinal fluid obtained by puncture from cases 

 of sleeping sickness in Uganda. Similar discoveries were made by Bruce, who also 

 found trypanosomes in the blood of those attacked with sleeping sickness. Sambon 

 regarded a species of Glossina as the transmitter. From consideration of the 

 geographical distribution of the disease Christy regarded Glossina palpalis as the 

 transmitter. Brumpt first thought it was G. morsitans, but, later, supported the 

 view of G. palpalis. Bruce, Nabarro and Greig also named the same insect as 

 the transmitter, not only for geographical reasons but also because healthy apes 

 became infected by the bite of certain G. palpalis. The inoculation of cerebro- 

 spinal fluid from subjects of sleeping sickness into the spinal canal of apes (Macacus] 

 had the same result. 



Just as the discovery of the malarial parasites called forth a whole flood 

 of research memoirs which were followed by a second series on the relation of 

 the mosquitoes to malaria, so a similar outpouring occurred after the discovery 

 of the pathogenic trypanosomes of mammals and men. In both cases the inquiry 

 was not limited to the stages in man and other vertebrate hosts, but the fate 



