1910.] and T. rhodesiense as seen in Rats and Guinea-pigs. 217 
Rat 7.—T. rhodestense in Piebald Rat, 2, weight 170 grammes, inoculated 
with 1,000,000 trypanosomes. Weight 182 grammes at death, but 
pregnant. 
WDA an's dasicieonscces | 1 | 2 3 | 4 5 6 
Parasites, per c. mm. ... -— _- 8 5852 27,916 16,468, killed 
MNBT De eae cctssiewsnstseeee 38 62 55 67 66 
Heart blood of Rat 7: many flagellates, few rounded bodies. 
Liver : equal numbers of flagellates and rounded bodies. 
Lungs: three times as many latent bodies as flagellates. 
Bone marrow: large rounded bodies. 
Spleen: no flagellates seen, but many rounded bodies 
Splenic vein blood: twice as many flagellates as rounded bodies. 
Mesenteric gland fluid: many flagellates. 
Lymph: rounded bodies and Crithidia-lke forms. 
Placental blood: living flagellates, few rounded bodies. 
13 embryos: serous fluid contained a very few trypanosomes. 
Embryonic liver: no flagellate trypanosomes seen. 
From counts of the number of trypanosomes in the peripheral blood 
daily, and from examination of carefully prepared smears of organs, it is 
found that latent bodies are most numerous when the flagellate parasites 
are few. If inoculated animals be killed at these periods, very few flagellate 
trypanosomes are found in the spleen and bone marrow (see preceding 
tables), but many latent bodies are present in those organs, while rounding 
forms are seen especially in the lungs. 
In the peripheral blood, on the upward slope of the curve representing 
the numbers of the parasites from day to day, the parasites increase in 
numbers by longitudinal division to a maximum. At or about this period, 
the formation of rounded or latent bodies begins, and takes place especially 
in the internal organs. 
If rounded (latent) bodies, derived from the internal organs of an infected 
rat, be placed in warm fresh blood drawn from a normal, uninfected rat, 
then growth of some of the rounded bodies towards the flagellate trypaniform 
stage can be seen under the microscope, as is detailed in a subsequent section 
of this paper. 
Five guinea-pigs (three inoculated with 7. rhodesiense and two with 
T. gambiense), dying in various stages of trypanosomiasis, were carefully 
examined, and fresh preparations and smears of their internal organs were 
