1076 PATHOGENIC PROTOZOA 



drawn out to a point posteriorly, is armed with a single flagellum in 

 front, and has no undulating membrane. It is a doubtful species and 

 of no present importance. 



GENUS 2. Bodonidae Prowazekia (Hartmami and Chagas). 

 These organisms, the only examples of the Bodonidce of medical inter- 

 est, are of some importance, since they have been cultivated from 

 human feces on agar plates. The genus was founded for Prowazekia 

 cruzi, a species discovered in human feces in Brazil. Other species are 

 urinaria, asiatica, parva, weinbergi and javanensis. There are two 

 flagella, arranged in the heteromastigote manner, that is, one flagellum 

 projects forward and one trails behind. There is no undulating mem- 

 brane, but in stained specimens a second nucleus is seen, the kineto- 

 nucleus or blepharoplast. They are also found in water, and are 

 probably not the cause of any disease. 



GENUS 3. Trypanosomidse. History of the genus. In 1841 Val- 

 entine discovered the first hemoflagellate in the blood of a trout now 

 known as Trypanoplasma valentini* and the following year Gruby 

 described a flagellate in frog's blood and named it a ' ' trypanosome. ' ' 

 It was not until 1878 that Lewis discovered the rat trypanosome, 

 Trypanosoma lewisi. The first pathogenic member of the genus was 

 noted by Evans in 1889 in the blood of Indian horses sick with surra, 

 Trypanosoma evansi. Bruce in 1894 described the trypanosome of 

 Nagana, Trypanosoma Irucei a horse disease of Zululand, and also 

 demonstrated its transmission by the tsetse fly, glossina palpalis. In 

 1894 to 1899, Rouget, Schneider and Buffard found the trypanosome 

 of Dourine, or "mal de coit," among Algerian horses. Elmassian 

 described, in 1901, the South American horse disease, "mal de 

 caderas," and discovered the parasite, Trypanosoma equinum. Since 

 this time a large number of new species have been discovered, the 

 more important of which will be described. 



Morphology. The morphology of the trypanosomes, while subject 

 to many variations in detail, is still uniform as to the characteristics 

 of the genus, so that there is little difficulty in immediately recognizing 

 the parasite. The body is long and sinuous, tapering anteriorly to a 

 fine point called the flagellum; the posterior end is never so delicate 

 and is often quite blunt. All contain two nuclei, the larger being 

 called the trophonucleus and the smaller the kinetonucleus. The 

 trophonucleus is usually located midway in the length of the body, 



* Gauthier, M. C. E. Acad. Sci., 1920, 170, 69. 



