52 THOMPSON YATES AND JOHNSTON LABORATORIES REPORT 
arsenic has given better results both in the hands of Laveran and ourselves. The 
animals can live for a longer period ; the administration need not be so often repeated. 
The drawback is that the kidneys quickly become affected. Animals infected with 
T. dimorphon do not seem to react well to arsenical treatment by itself ; trypanroth 
medication only causes the parasites to temporarily disappear ; the combination of 
arsenic and trypanroth causes the parasites to be absent for a longer period. Various 
methods have been tried. Administration of trypanroth and arsenic together, or the 
dye first, followed in twenty-four to thirty-six hours by arsenic or vice versa. It is the 
latter treatment which has given most satisfaction in our hands. Laveran administers 
high doses of arsenic and follows twenty-four hours later with an intramuscular 
injection of trypanroth. 
Arsenic has been tried in combination with the other dyes but without results. 
Arsenic and human serum in the treatment of rats infected with Nagana and 
Surra have prolonged the life of the animals. A guinea-pig inoculated with T. Brucei 
did not seem to improve, the serum was given in amounts of ten c.c. once a week, 
but no more serum being obtainable the treatment had to be stopped, and at the end 
of three weeks the parasites then reappeared. Animals infected with T. dimorphon 
do not show as marked a reaction to serum treatment as do Nagana, Surra, etc.; the 
employment of arsenic and human serum does not appear to promise well. Human 
serum and arsenic combined has been tried on animals infected with T. gambiense ; 
the control animals treated with arsenic alone showed as much, if not more, improve- 
ment as those with the combined treatment. 
Arsenic and Baboon serum ; very little serum was obtainable, three mice infected 
with T. gambiense, T. dimorphon, and T. Brucei, respectively, were used. The results 
were indefinite. 
Other sera including horse, cow, sheep, goat, dog, cat, rabbit, and guinea- 
pig have been tried. The sera were produced from both healthy as well as from 
infected animals which had the disease in a chronic form or were apparently cured. 
The sera were used alone or in combination with arsenic, with disappointing results, for 
in no case could a definite and permanent decrease be ascribed to the action of the 
sera. Polyvirulent sera have also been tried without success. 
Atoxyl Experiments 
The trypanosomes and animals used for carrying out the investigation were 
as follows : — 
T. gambiense, in monkeys, dogs, puppies, kittens, rabbits, guinea-pigs, 
rats, and mice. 
T. Evansi, in horse, dogs, rabbits, guinea-pigs, rats, and mice. 
T. Brucei, in cow, rabbits, guinea-pigs, rats, and mice. 
T. equinum, in dogs, rabbits, guinea-pigs, rats, and mice. 
T. equiperdum, in pups. 
T. dimorphon, in dogs, pups, rabbits, guinea-pigs, rats, and mice. 
