562 TRYPANOSOMES AND TRYPANOSOMIASES 



resembling that of the hemosporidia of malaria in the body of the ano- 

 pheles mosquito. Gray, Tulloch, and Koch have claimed that ingested 

 mammalian trypanosomes (Trypanosoma gambiense and Brucei) 

 undergo such developmental changes in the tsetse fly, but Novy has 

 shown that what these investigators believed to be developmental 

 male and female sexual forms were in reality a different species of 

 trypanosoma parasitic in flies and mosquitoes and in no way connected 

 with the pathogenic trypanosoma of nagana. Neither surra nor 

 nagana, the two most important trypanosomiases spread by biting 

 flies, have even been found in man. There is, however, one human 

 infection, the celebrated African sleeping sickness, due to the Try- 

 panosoma gambiense, and mentioned briefly above, which is spread 

 by biting flies, and occurs over a large territory. It was first described 

 over a hundred years ago by Winterbottom, and its cause, a trypano- 

 some, was discovered by Dutton in 1901. The Trypanosoma gam- 

 biense of human sleeping sickness transmitted by Glossina palpalis 

 is pathogenic for a large number of animals, such as the monkey, 

 lemur, dog, jackal, cat, rabbit, guinea-pig, etc. 



Trypanosoma Americanum, n. sp. Crawley has recently reported 

 that he has obtained from cultures prepared from the blood of normal 

 cattle a new hitherto undescribed species of trypanosoma, which, 

 however, is not present in the blood of the animals as such, but in 

 an unknown form, which only develops into typical trypanosomes in 

 the artificial cultures. Crawley has named this non-pathogenic 

 flagellate, Trypanosoma Americanum (novum species). According 

 to the observer the organism can be demonstrated as follows : Blood 

 is drawn under all aseptic precautions from the jugular vein of a 

 cow by means of a sterile syringe and transferred to flasks of 100 c.c. 

 capacity. About 30 to 50 c.c. of blood is taken in each case. In 

 each flask are placed six to eight common faceted beads of rough 

 glass such as are used for cheap necklaces. The flasks containing 

 the blood and the beads are then shaken for a few minutes, which 

 causes the fibrin to collect around the beads. The defibrinated 

 blood is distributed to flasks and tubes containing nutrient (beef) 

 bouillon. Muttori bouillon may also be used. The inoculated flasks 

 and tubes are kept at room temperature. After two or three days 

 trypanosomes appear, and after a few more days they can be seen 

 without the aid of the microscope as little colonies on the surface 

 of the column of blood cells. Those colonies show as small, white 

 plates, and may be 3 to 4 mm. in diameter. They are readily dis- 

 tinguishable from bacterial contamination in that they are flat and 

 sharply circumscribed, while the masses of bacteria are always 

 more or less diffuse and tend to cloud the bouillon. These trypano- 

 somes are not present as such in the freshly draw r n blood of cattle, 

 but the evidence is that they develop in the cultures from round 

 or oval bodies. From these lenticular bodies are first formed, then 

 a flagellum is developed, and the flagellate now formed is of the 



