224 Dr. H. B. Fantham. History of T. gambiense [Oct. 15, 
Sleeping Sickness also explains recurrence of trypanosomiasis after it has 
apparently died out in an infected animal. In such cases the latent bodies 
are present in the host all the while in such organs as the spleen and bone 
marrow. 
During these researches it has been found that flagellate trypanosomes 
(500,000 to 2,000,000 in number) inoculated into a rat or a guinea-pig can be 
detected in the peripheral blood-stream (in 1 cubic millimetre of blood) of the 
host for some 10 to 12 hours, or even 18 hours after inoculation. During and 
after this period, that is, during the incubation period of the parasite, a few 
rounded forms of trypanosomes can be found in a cubic millimetre of 
peripheral blood. 
Biot (1910) writes of the “revivifying action” of physiological salt solution 
on trypanosomes (7’. lewisz), especially in fluid from the liver of a rat dead 
61 days (kept in the cold, unopened). Biot does not explain the phenomenon. 
However, it is capable of explanation, for in the liver latent bodies of 
trypanosomes are present, which, under the relatively favourable environment 
of isotonic salt solution, flagellate and become typical trypanosomes. 
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. In this 
connection the work of B. Moore, Nierenstein, and Todd* on the combined use 
of salts of mercury and arsenic should be considered. 
Note on the Degeneration of Trypanosomes. 
All flagellate trypanosomes do not become rounded and form latent, non- 
flagellate bodies, but some of them degenerate and die. The degeneration may 
take various forms—some become («) somewhat irregular and almost 
amoeboid with pale-staining cytoplasm and vacuoles (figs. 44, 45), others () 
exhibit chromatolysis, wherein the nucleus becomes poor in chromatin and 
chromatoid granules occur in the cytoplasm (figs. 446—49), while others (y) 
exhibit marked vacuolation (fig. 50). Such degenerating forms may be seen in 
various internal organs of the host, such as the lungs and spleen, especially 
during the period of formation of latent bodies. 
It is also very probable that some of the latent bodies themselves die and 
do not flagellate, for some shrunken latent bodies, with undifferentiated 
contents, can be seen in the spleen. 
* © Ann. Trop. Med. and Parasitol.’ (1907), vol. 1, pp. 275—284, 
