The number and morphology of trypanosomes in the blood and lymph of rats infected with Trypanosoma brucei and T. congolense.

The thoracic lymph duct of rats infected with Trypanosoma brucei and with T. congolense was cannulated at different stages of infection. Trypanosomes were always present in the lymph of rats infected with T. brucei, wheras they were absent or very scarce in the lymph of rats infected with T. congolense. There were greater fluctuations in the numbers of trypanosomes in the blood than in the lymph. The intra- and extravascular populations of T. brucei differed: stumpy forms were present only in blood; dividing forms were usually more numerous in lymph.