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178 single example is discovered. Sometimes none can be found; rarely are they abundant. In the same case they are sometimes present, sometimes absent. Centrifuging the blood is not of much assistance. Dutton and Todd have emphasized the value of lymphatic-gland puncture and examination of the aspirated lymph, particularly in the earlier stages of the disease when the glands are soft and before they have become sclerosed; then the trypanosomes are fairly abundant in the lymph. An ordinary hypodermic syringe suffices to aspirate a sufficiency of lymph. Films of the lymph so obtained are prepared and stained in the ordinary way. Cerebro-spinal fluid, obtained by lumbar puncture and centrifuged, affords another though not always a practicable means of finding the parasite. Failing discovery of the parasite by blood or lymph examination, recourse must be had to animal inoculation, 10 to 20 c.c. drawn from a vein being used for that purpose. Of the ordinary laboratory animals the most susceptible, and therefore reliable, are the guineapig, the rat, the dog, and certain monkeys——Macacus and Cercopithecus. Such inoculations are of value as a test of recovery, as well as for diagnosis.

The trypanosome is easily stained by most dyes; convenient stains are those in use for malaria work. A sixth objective suffices to find the parasite.

Treatment.—— Although something may be done to relieve symptoms and delay the fatal issue in the sleeping-sickness stage of trypanosomiasis, it is only in the earlier stages of the infection and by the persistent and energetic use of arsenic or antimony, or both, that a cure can be effected, and that in a proportion of cases only. Other drugs have been shown to have some influence on the trypanosome infections of the lower animals, but their therapeutic value in those of man is practically negligible. The effects of the administration of arsenic compounds on a heavily infected animal are very marked, after a preliminary and marked increase in the number of parasites in the peripheral circulation.