Abstract
In the blood of an experimental monkey (Macacus rhesus), Dr. Richard Lamar found on October 28, 1911, an actively motile trypanosome. This discovery led to my examining the blood of all of the monkeys at the Rockefeller Institute.
In examining 130 monkeys, 28 were found infected with trypanosomes. The infected monkeys had been used for experiments between July 17 and October 6. Six monkeys used on or before July 17 were negative, and 80 others, some normal, the rest used after October 6, were also negative.
With but one exception, all of the monkeys examined belonged to the Macacus rhesus species.
The trypanosomes found in the 28 monkeys were apparently of the same kind. They have been successfully inoculated into one monkey (Macacus rhesus), six mice, two rats, one guinea pig, and one young rabbit. In none of these animals has a rich infection been seen. The two rats were infected on the 8th day, the six mice between the 9th and the 52d day, the guinea pig and rabbit on the 16th day, and the monkey between the 16th and the 24th day. The trypanosomes do not appear to be very pathogenic.
The micronucleus is usually at the estrerne posterior end of the parasite, is strikingly large, measures 1μ or more in diameter, and often projects on either side of the parasite. The nucleus is oval, measures 1⅔ to 2⅔μ in its long diameter, and is situated near the juncture of the anterior ⅓ and the posterior ⅔ of the body. The flagellum is very long, the free part measuring 10 to 12⅓μ. The entire length of the parasites thus far measured has varied between 25 and 28μ, the breadth between 2 and 2¼μ.
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