42 THOMPSON YATES AND JOHNSTON LABORATORIES REPORT 
Glands were removed from lightly infected animals — strains, T. gambiense, 
T. dimorphon, T. evansi 1 — showing parasites in only scanty numbers in the blood. The 
glands were immediately mashed up with citrate solution and the extract injected into 
the peripheral cavity of susceptible animals. Eleven experiments were done. In nine 
the animals were infected only after a prolonged incubation ; in two cases the animals 
never showed parasites. Controls inoculated with blood and citrate became infected 
in a shorter time. 
Occurrence of Parasites in Blisters 
One of the experimental animals having a blister the exudate from the small 
bleb was noticed to contain a few trypanosomes. By means of cantharides plasters 
small blisters were made, and the serum was examined from two of the natives and some 
of the animals. The results were not encouraging. On occasions when the blood 
was negative the fluid from the blisters was also negative, and on days when the 
blood was positive only a very small number were seen in the exudate. Sufficient 
exudate was collected and mice inoculated. After an incubation period of twenty- 
one days in two out of four mice inoculated intraperitoneally with o - 5 and ro c.c. 
parasites were seen in small numbers. 
Diagnostic Methods 
Much attention has been directed to find some method of diagnosis in cases 
where the blood and gland-juice examinations fail to show parasites; in cases of 
failure, and when the centrifuged blood is also negative, resource must be had to 
inoculation. Dutton and Todd record a certain number of their inoculated rats 
failing to show signs of infection, even when inoculated with blood verified to 
contain motile parasites. All the rats inoculated from the natives have shown 
parasites in their blood, yet in some cases the incubation period has been prolonged 
to thirty-two days. Rats are in many ways unsatisfactory, as the parasites may be 
present in only very small numbers. Inoculation of larger animals, rabbits, guinea- 
pigs, and cats are also open to the same objection. Monkeys are most suitable, 
since they are easily infected ; then come young pups, kittens, rabbits, and 
adult dogs. Advantage was taken of the periods when the trypanosomes were 
absent from the peripheral blood of the natives. If after several days the blood 
still remained negative, small quantities of blood, ten to thirty c.c, were withdrawn 
from one of the superficial veins and, combined with citrate solution, the mixture was 
i. While experimenting with T. brucei in Professor Kitt's laboratory, Veterinary School, Munich, and at McGill Univer- 
sity, a series of animals were inoculated with extracts from the mashed up organs, glands, bone marrow, etc., of infected 
animals. Infection quickest with blood mixture, then bone marrow, spleen and liver, kidneys and adrenals, glands, brain, cord. 
A repetition of the above with T. gambiense and other trypanosomes has given almost the same results. Pieces of organs 
removed aseptically and inserted whole under the skin or in the peritoneal cavity of rats and guinea-pigs have infected the 
animals after a more or less prolonged incubation period. Pieces of organs left under the skin or in the peritoneal cavity for 
some hours and then taken out and examined showed trypanosomes more degenerated and in less numbers than in control pieces 
examined. Celloidin sacs filled with blood containing parasites and placed in the peritoneal cavities of rats and pigs for a time 
show the usual degenerating, deformed trypanosomes. 
