On the supposed Development ofTrypanosoma lewisiin Lice and Fleas; and the Occurrence ofCrithidia ctenophthalmiin Fleas

Abstract

1. The alimentary tracts of 104 lice (Haematopinus spinulosus), which had been taken from rats infected withT. lewisi, were examined. In 51 lice no trace ofT. lewisicould be found. In 53 liceT. lewisi, unchanged in every particular, was found in various parts of the gut. The trypanosome was seen to be quite unchanged in stained preparations.2. The alimentary tracts of 45 fleas (Ctenophthalmus agyrtes), which had fed on infected rats, were examined. TheT. lewisicould not be found at all in 43 fleas. They disappeared very rapidly from the ingested blood and could not be found in stained preparations. In 2 fleas trypanosomes were found, but they did not differ in form from those seen in the blood of the rat.3. 263 lice were examined from rats which were apparently uninfected withT. lewisi. No form ofT. lewisiwas discovered in fresh or stained preparations.4. 31 fleas from uninfected rats were dissected and their alimentary tracts examined. No trace ofT. lewisiwas found.5. 15 lice were examined 18–48 hours after their removal from an infected rat.T. lewisiwas found in 7 of these, but they shewed no developmental changes.6. Observations made upon 36 lice from infected rats shewed that at the earlier stages of digestionT. lewisiwas more often found than at the later stages. In some lice however trypanosomes could not be found at the early stages of digestion, although they were present at an advanced stage of digestion.7. The examination of other organs than the alimentary canal in fleas and lice did not shew any form ofT. lewisi.8.Crithidia ctenophthalmiwas found in 9Ctenophihalmus agyrtes.9. About 370 lice and 75 fleas were examined but no evidence was obtained of developmental changes ofT. lewisiin either fleas or lice.