17 
trypanosome fever had been under treatment with trypan-red and 
arsenic for a short time before he returned to the Congo with favour¬ 
able results --the parasites were longer absent from the peripheral 
circulation ; his general blood condition was better; his temperature 
was almost normal. 
‘ I present the results of my experiments tentatively. I have used 
the term “ apparently cured,” as any one with an intimate knowledge 
of T. gambiense and other forms of trypanosomes in animals knows 
how difficult it is to say that an animal is not infected. This 
is especially the case with the human parasite. In a previous 
paper I have recorded cases in which the blood has been negative for 
nearly a year in rats known to have been infected, and which at the 
expiration of that time showed parasites once more in their blood. 
‘ I do not believe that sodium arseniate alone will be found of 
great practical value, nor do I think atoxyl is a perfect preparation, 
from its toxic effects on canines and felines, but it is an advance on 
arsenious acid, and, if further efforts be made to produce a substance 
like trypan-red, but less irritating in action, the combination ought 
to be of service in the treatment of trypanosomiasis in man.’ 
Thomas at about the same time made a communication to the 
Royal Society (received April 8 th, 19*^5* read May iith, 1905) 
upon the experimental treatment of Trypanosomiasis in animals with 
Atoxyl, Atoxyl and Trypan-red, and Trypan-red alone. The com¬ 
munication was the result of exhaustive experiments upon animals 
infected with five strains of T. gambiense^ one a very virulent one 
taken from a case of sleeping sickness, and the rest the common 
animal strains. The Atoxyl was given in two ways. 
(1) High doses at intervals of a week. 
(2) High initial dose and then reduced amounts administered 
three times a week. 
He concluded, my hands the arsenic-anilin compound {Atoxyl) 
has given far better results than treatment with sodium arseniate. The 
advantages of its administration intravenously or subcutaneously in high 
doses over a length of time — namely, its less toxic properties, the absence of 
all tendency to cause sloughing and the apparently longer action of the 
drug, make me believe that the employment of this compound is indicated 
in the treatment of human trypanosomiasis.* 
A third paper by THOMAS in collaboration with Breinl upon 
c 
