‘a? 
1910.] and T. rhodesiense as seen in Rats and Guinea-pigs. 223 
trypanosomiasis. In other words, persistent infectivity in the case of 
trypanosomes is explained by rounded bodies. 
I have performed this experiment (inoculation of latent bodies) on two 
occasions. In the first experiment a rat was inoculated with one drop 
of spleen-pulp (from Rat 7) mixed with a little sterile physiological salt 
solution, the mixture containing no flagellates. The inoculated rat developed 
trypanosomiasis on the 6th day, dying on the 12th day. The daily counts of 
this rat were as follows :— 
Ways ty, RR SM AL Ios | 6 ry alt Bie a 20 10 ia 12 
ar : 
| Parasites, per| — | — |—|— —) 4 | 864, 2196 | 4308 | 380,600 | 10,000 | 75,200 
i. oGehoaneo’ | | 
Secondly, a further experiment was tried, since it was considered that the 
parasites in one drop of spleen-pulp solution might be too numerous to count 
accurately, and that a few flagellate trypanosomes might be contained 
therein, for although a most minute search was made for flagellates in the 
fluid before inoculation, yet a very few flagellates might have remained 
undetected. Accordingly, in the second experiment, 1 cubic millimetre of 
spleen-pulp solution in sodium citrate was inoculated intraperitoneally. 
Careful examination of samples of the solution used, both fresh and stained, 
showed no flagellate trypanosomes, but many rounded bodies. The actual 
fluid used for inoculation also showed no flagellate trypanosomes when 
microscopically examined fresh. The rat thus inoculated developed try- 
panosomiasis, parasites being found on the 8th day, and it died on the 18th 
day. The daily counts of this rat are appended :— 
Dawe date ccc a TOA ze i AR he BE) 6 7 8 9 10 11 
| Parasites, per c. mm. | — | — | — | — | — | —| — a 960 2800 12,000 
Days. « terta.sottia 12 13 14 15 | 16 | 17 18 
49,200 | 18,200 | 6400 | 2120 20,600 
Parasites, per c. mm. 50,240 128,000 
The two rats inoculated with non-flagellate, latent bodies of 7. rhodesiense 
showed incubation periods rather longer (5 to 7 days) than usual (2 to 4 days) 
with rats inoculated with flagellate 7. rhodesiense. 
The occurrence of non-flagellate bodies in the life-cycle of the parasites of 
VOL. LXXXIIL—B. S 
