1910.] and T. rhodesiense as seen in Rats and Guinea-pigs. 225 
Summary and Conclusions. 
(1) Non-flagellate stages of trypanosomes, such as 7’. gambiense (Dutton) 
and 7. rhodesicnse (Stephens and Fantham), occur. 
(2) These non-flagellate stages (“latent bodies” of Moore and Breinl) are 
especially found in the lungs, spleen, and bone marrow, during periods of 
decrease of trypanosomes in the peripheral blood of the host. 
(3) They are in process of formation at or near the time when the 
trypanosomes are most numerous in the peripheral blood. The formation 
of latent bodies takes place especially in the lungs, and they collect in the 
spleen and bone marrow of the host. 
(4) In the formation of non-flagellate stages, some of the cytoplasm and 
the flagellum of the trypanosome are disintegrated. The non-flagellate body 
contains the nucleus and blepharoplast (kinetonucleus) of the trypanosome. 
(5) Non-flagellate (latent) bodies can be seen to grow and _ flagellate, 
turning into trypanosomes, when placed in fresh, warm, uninfected blood. 
(6) Latent bodies of 7. rhodesiense, inoculated into a rat, flagellate and 
produce trypanosomiasis. 
(7) The non-flagellate (latent) bodies of trypanosomes (7. gambiense and 
T. rhodesiense) are the post-flagellate stages of one generation of trypanosomes 
and the pre-fiagellate stages of the succeeding generation of trypanosomes. 
(8) There is a life-cycle of trypanosomes (7. gambiense and T. rhodesiense) 
in Vertebrate hosts, comparable with those of Crithidia and Herpetomonas in 
the alimentary tracts of various Invertebrates. The latent (relatively 
resistant) stages of trypanosomes occurring in Vertebrates are separate from, 
and in addition to, stages of the parasite which may occur in the Invertebrate 
carrier (for example, Glossina). 
(9) In the treatment of trypanosomiasis by drugs, careful note must be 
taken of the occurrence of rounded non-flagellate or latent forms of the 
parasite. A drug needs to be found which will either prevent the formation 
of rounded (latent) stages, or disintegrate those latent bodies already formed. 
REFERENCES TO LITERATURE. 
Biot, C. (1910), “ Action revivifiante du Chlorure de Sodium sur les Trypanosomes,” 
‘C. R. Soc. Biol.,’ Paris, vol. 68, pp. 615, 616. 
Fantham, H. B., and Thomson, J. G. (1910), “Enumerative Studies in 7rypanosoma 
gambiense and 7’. rhodesiense in Rats, Guinea-pigs, and Rabbits: Periodic Variations 
disclosed,” ‘Roy. Soc. Proc.,’ B, vol. 83, pp. 206—211. 
Hindle, E. (1909), ‘The Life-history of Trypanosoma dimorphon,” ‘Univ. Calif. Publica- 
tions in Zool.,’ vol. 6, pp. 127—144, 3 plates. 
Moore, J. E. S., and Breinl, A. (1907), “‘The Cytology of the Trypanosomes, Part I,” 
‘Ann. Trop. Med. and Parasitology,’ vol. 1, pp. 441—480, 5 plates. 
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