TRYPANOSOMIASIS EXPEDITION TO THE CONGO 79 
November 6 have not become infected ; and one large rat and two small ones inocu- 
lated on April 22 have not, so far, become infected. On October 9, 1903, the weight 
of the horse was 513 pounds. On April 26, 1904, it was 506 pounds. The animal 
shows no symptoms, its temperature is regular (from 99 0 to ioi°F.), and its appetite 
is good. There is no oedema, and its coat is in good condition. 
Strain Derived from Cerebro-spinal Fluid of Uganda Cases of 
Sleeping Sickness' 
Rats. — 1. Young rats : Twelve experiments. Incubation period from four to 
thirteen days ; average length, nine days. Parasites were fairly constantly present, 
but usually rather in small numbers. Duration from fourteen to forty-one days. 
2. Adult rats : Twelve experiments. Incubation period from four to twenty days ; 
average length, thirteen days. Parasites were fairly constantly present in small 
numbers in the early stages of infection, later they became rare. Duration from 
sixteen to one hundred and forty-nine days. 
Mice. — Incubation period from five to six days. Parasites were rarely present 
in the blood after the first appearance. Duration was from nineteen to forty-seven 
days. 
Guinea-pigs. — Four experiments. None yet infected. Five weeks have elapsed 
since inoculation. Sub-inoculations into mice and rats so far have been unsuccessful. 
No symptoms have yet been observed. 
Rabbits. — Incubation period from seven to nine clays. Parasites are constantly 
present, tending to become more numerous as the disease advances. Marked and 
fairly rapid loss of weight is observed. The rabbits are still living. Anaemia is a 
noticeable symptom. 
Cats. — One experiment. A large grey cat was inoculated intravenously from a 
rat. Incubation was six days. The temperature rose on the evening of the sixth 
day to 1 05 3 F. 
Dogs. — One experiment. Inoculated intravenously from a rat showing fairly 
numerous parasites. Trypanosomes appeared in the blood on the seventh day. The 
temperature has remained normal. The animal has, so far, shown no symptoms. 
Puppy. — One experiment. Age four-and-a-half months. Inoculated on March 20 
from a rat. Trypanosomes appeared in the blood on March 27 and have since 
been constantly present, although not more numerous than from two to five to a 
field. The temperature has varied between 101 0 and io3°F. There was no rise 
with the appearance of parasites in the blood. Diminution in haemoglobin and red 
cells has been observed. The animal has lost strength considerably. 
1. This was sent to us in a rat which had been inoculated from a monkey infected from the cerebro-spinal fluid of a 
case of sleeping sickness ; it was, therefore, only in its second passage. 
