W. L. Yakimoff and others 51 
fection had appeared became infected. Later, guinea-pigs inoculated after 
97 and 125 days did not become infected. 
This bull, therefore, had suffered from trypanosomiasis but had recovered 
from the infection. 
However, this did not render him immune. 
For example, the serum taken 130 days after infection and mixed in 
different proportions with the same trypanosome from the “ Bokhara 55 camels 
(as well as with the trypanosomes of Bokhara donkeys, which have already 
been proved to be identical with those of the camel) did not protect mice from 
infection after intraperitoneal inoculation, as seen in the following table: 
Trypanosomes 
from camel 
Quantity 
of serum 
2nd day 
3rd day 
4th day 
5th day 
271 
1-0 c.c. 
0 
0 
+ 
272 
0-5 
0 
0 
+ 
273 
0-25 
0 
0 
+ 
Trypanosomes 
from donkey 
268 
1-0 c.c. 
0 
0 
0 
+ 
269 
0-5 
0 
0 
0 
+ 
270 
0*25 
0 
0 
0 
+ 
143 days after the first infection the bull was inoculated subcutaneously 
for the second time with the blood of a mouse with a larger number of trypano¬ 
somes (10-15 parasites per field) and in 4 days the trypanosomes made their 
appearance in the blood, but later they disappeared. 
After the first introduction of the virus the temperature rose from 38° 
to 40° in 3 days, and later, during 20 days, it rose to between 38° and 41° 
and higher. Afterwards it became more regular and fluctuated between 
39 and 40°. No symptoms of the disease were observed. 
VIII. THE INFECTION OF BIRDS 1 . 
The following birds have been infected: goose, fowl, duck and pigeon. 
(a) Goose. Inoculated intravenously on- 16 October, 1914, from mouse 
No. 22 (quantity of trypanosomes + + ++). Its blood was examined during 
37 days; on the last day the bird succumbed, and during the whole period 
trypanosomes were never observed in the blood. Nevertheless, the goose 
proved to be infected, for two mice inoculated—one after 7 days (subcutane¬ 
ously), and another after 21 days (intraperitoneally)—became infected. 
(b) Fowl. On the 16 October, 1914, inoculated intravenously from the 
same mouse as the goose. Examination of the blood during 26 days did not 
reveal the presence of trypanosomes in the blood. Two mice inoculated with 
its blood—after 7 and 24 days respectively—did not become infected (examina¬ 
tions were conducted during 34 days). 
1 By W. L. Yakimoff and S. K. Popoff. 
4—2 
