164 H. M. WnODCOCK. 



in many cases thrown light upon the etiology of maladies hitherto ohscnre. 

 Thus Rouget, in 1896, ascertained that a Trypanosome is the cause of the 

 illness known as Dourine, which afflicts horses, mules, etc., in Northern 

 Africa and the Mediterranean region. A very deadly malady of horses in 

 South America, known as Mai de Caderas (hip-paraplegia) was shown to be 

 due to one of these parasites by Elmassian, Sivori and Lecler, and Voges, 

 working independently, in 1901. Similarly Theiler showed (1902) that 

 another species, a very large one, causes a distinct disease of cattle in the 

 Transvaal, known as Galziektc (bile disease). Since then, moreover, other 

 varieties of trypanosomosis have been observed in different regions of 

 Africa, but the exact specific nature of the parasites causing them remains, 

 in many cases, problematical. 



Finally, there is the discovery of the human parasite. The credit for 

 first recognising a Trypanosome in human blood, and describing it as such, 

 must undoubtedly be assigned to Dr. Nepveu (1898), although it is possible 

 that Barron, who some years earlier reported having found Flagellate organ- 

 isms in the blood of an anpemic woman at Liverpool, was in reality the first 

 to notice these parasites in man. His description of them is, however, much 

 too meagre to render this at all certain. Trypanosomes were next seen in 

 Senegambia, in 1901, in the blood of a European suffering from intermittent 

 fever. Porde first found the parasites, but was uncertain of their nature ; 

 he showed them to Button, who recognised them as Trypanosomes, and 

 o-ave this form the name of Trypanosoma gambiense. A year later 

 (1902) Castellani discovered a similar parasite in the cerebro-spinal fluid of 

 patients suffering from sleeping sickness in Uganda, and it has since been 

 conclusively proved by Bruce and Nabarro that this organism is the true 

 cause of that ghastly disease. In all probability the species is the same as 

 that investigated by Dutton (see below, under " Effects on host," p. 177, 

 and also in the Systematic section). 



More important, from the standpoint of zoology, than these interesting 

 medical discoveries, have been the investigations by Laveran and Mesnil, 

 Leger, Scbaudinn and others during the last two or three years upon 

 numerous " tolerated " species (many of them new) wliich supply, indeed, 

 nearly all the material for the sections on morphology, life-history, and 

 taxonomy. At the present time, scarcely a month passes without some new 

 form being described by one or other of these indefatigable researchers, and 

 it may be confidently expected that with such a rate of progress our know- 

 ledge of the complete life-cycle will not for long remain dependent on so 

 few observations as is at present the case. 



