268 
and examined frequently for at least three months in tlie case of 
Trypanosoma brucet, longer, if Trypanosoma gambiense was in 
question, before being considered to be uninfected. Rats and mice 
were, as a rule, used for .such subinoculations in preference to other 
animals, as indeed they were throughout our entire work. 
II. COMPLETION OF PART I 
1 he three control rats, treated by Atoxyl alone, which were alive 
at the date of publication of the last paper, have all since died of 
trypanosomiasis at periods varying between one hundred and two 
hundred and twenty-six days after the cessation of treatment 
Trypanosomes (Trypanosoma brucei) have never recurred in any 
of the rats from which they had disappeared through the use of 
Atoxyl followed by bichloride of Mercury. All of the rats, save one, 
have died of pneumonia or have been killed because of ^kin diseases, 
None of the animals subinoculated from them, either before or at 
death, have become infected. One rat lived five hundred and 
nineteen days after inoculation, and then died from a skin affection. 
Nearly all the others had lived well over two hundred days before 
they died or were killed. It therefore seems justifiable to conclude 
that the rats, mentioned in this series of experiments, from which 
the trypanosomes were absent when Part 1 of this investigation was 
pu lished, were definitely cured of their infection by Trypanosoma 
brucei. 
All the rats treated by Ato.xyl followed by Donovan’s solution c 
o pneumonia m from one hundred and thirteen to one hundred ; 
y-one days after inoculation ; three of them died on the < 
of 1-ti ^ fifty-first day. Trypanosomes had reappeared in n( 
thpi u they appeared in the animals subinoculated fr 
j. seems probable that these animals were also cured of th 
trypanosome infection. 
a sen'pc^nf^^?^” 'noculation and normally following death 
which bar! ^ cured that no immunity was acquired by anim 
treatment ^ af, 
conferred nnn fk ^ ^°fic>\\ed by Mercury; n neither was immiini 
inorulation became infected and quickly died c 
