W. L. Yakimoff and others 49 
We cannot state whether this ram had acquired immunity, as it succumbed 
in our absence. 
(g) Sivine. On the 20th October, 1914, a young pig was inoculated 
subcutaneously with the blood of an infected foal (quantity of trypanosomes 
+ f.). 
Trypanosomes appeared in the blood after 21 days and were again ob¬ 
served twice: on the 53-54th day, and on the 71-72nd day. During the rest 
of the time they were invisible. 
The animal succumbed 73 days after infection. 
The pig was emaciated. 
(h) Horses. These animals were easily infected with this trypanosome. 
We have inoculated one foal subcutaneously. The average temperature 
during the 8 days preceding the infection was 37-8° (from 36*9° to 38-4°). 
After infection it rose on the 8th day to 40-5°, but next day it fell to 39*1°, 
and on the third to 38-4°. 
Later it rose above 40° seven times: 
On the 23rd day to 40*2°, 
„ 31st „ 40-1°, 
„ 46th „ 40-9°, 
„ 60th „ 41-0°, 
„ 68th „ 40-3°, 
„ 76th „ 40-1°, 
,, 81st ,, (day before death) to 40-5°. 
During the remaining time it was below 40°, but nearly always above the 
average; only twice did it fall below: 
on the 58th day to 36-8°, 
and ,, 64th ,, 36-4°. 
On microscopical examination of the blood trypanosomes appeared for 
the first time on the 19th day after infection. However, a mouse inoculated 
on the 9th day (i.e. on the next day after the first rise of temperature) with a 
small amount of blood from the foal into the peritoneal cavity became infected 
(trypanosomes appeared in the blood on the 5th day, and the mouse suc¬ 
cumbed on the 7th). Similarly, two guinea-pigs inoculated intraperitoneally 
on the 12th and 17th days of the disease became infected (trypanosomes 
appeared in the blood on the 8th and 10th days). 
From these results we may conclude that trypanosomes were present in 
the blood long before they could be found on microscopical examination; 
probably, they were already present on the 8th day after the foal was infected. 
During the whole course of the disease the parasites appeared in the blood 
during seven periods: 
Parasitology xi 
4 
