TRYPANOSOMES

minute biood or ody-fluid parasites belonging to the Yagellata or Mastigophora groups of he Protozoa. To man they are of great nportance, for although many harmle 9rms are know —parasitic in fishes, mphibia, mammals, and other versbrates—there are others which cause erious or fatal diseases (tryp a no so pees to man) and to his domesticated ck, re elongated transparent Protozoa, fhich exhibit, when suitably stained,. somewhat cylindrical body, pointed t+ the ends, with a large nucleus (trohhonucleus), @ single long flagellum ttached along the body by an undulatng membrane, but free at one end and inking into the bedy at the other end ir kinetonucleus. They move in the Jood-fluid with a forward, wriggling notion, generally with the free flagellum n front. Some idee of their minutene nay be gathered from the fact that the ody of 7. gambiense, the cause of sleepng-sickne , is only about,,, inch long. Trypanosomes occur in the blood yr body-fluids in varying numbers at lifferent times, owing usually to their cles of reproduction by simple division yr fi ion. From one land vertebrate © another they are borne by insects, uch as tsetse-flies, mosquitoes, fleas, ice, bugs, etc., or by ticks, whereas eeches act as intermediaries, where quatic vertebrates are concerned. In he ‘carrier’ distinct developmental stages ometimes occur. The trypanosomes which occur in vild animals in nature appear to be armle , and it is usually only where nan or domesticated animals cro the ath, as it were, of such species that lisease conditions become po ible. Phe trypanosomes in an unnatural host, ye they few or many, set up proce es f poisoning with which the host cannot ope, and the result is fever and often leath. Some well-known types of tryJanosomiasis are the fatal sleeping ick ne of the natives of Africa caused yy TT. gambiense and carried by a tsetse-fly’ disease, which renders great racts of land in Africa impo ible to attle, caused by 7’. bructi, and carried yy Glo ina morsitans; ‘surra’ in horses, nules, and elephants in India, the PhilipPines, and W. Indies; durine in horses; and ‘mal de caderas’ in S. American horses, transmitted by a fly—Stomozxys.