,T. D. E. Holmes 
77 
interval of one day between each dose. The amount of arsenic was 
gradually increased as the animals showed a tolerance to the drug. 
In addition to these cases here mentioned, a few animals, which were 
put under this treatment, showed an intolerance to the arsenic and 
each dose was followed by toxic symptoms. In these cases treatment 
was abandoned. 
The administration of arsenious acid had no prophylactic effect even 
when the surra inoculation was made 24 hours after the dose of arsenic. 
Arsenious acid and atoxyl. Two systems of combining these drugs 
were tried. 
In the first, the atoxyl and arsenic were given alternately, five doses 
of each, with an interval of one day between each dose. In a former 
paper (Holmes, 1909) some of these cases described here were stated 
to have been treated with atoxyl and orpiment. In this same paper I 
drew attention to the fact that the sample of orpiment used was a com¬ 
mercial one, obtained from a dispensing chemist. On analysis this was 
found to contain 95 to 97°/ 0 of free arsenious acid. Consequently, I 
have here included these cases as being treated with arsenious 
acid and atoxyl. In a number of experiments, some of which are 
not yet finished, we have tried treatment on the lines advised by 
Laveran and Thiroux with atoxyl and “ orpiment precipite,” but the 
results up to the present have been negative. 
In the second system of treatment, the arsenious acid and atoxyl 
were given as follows. Arsenious acid solution (drench) (Loeffler and 
Ruehs), atoxyl (subcutaneously) and arsenious acid (bolus) were admini¬ 
stered on consecutive days. These three doses were repeated once or 
twice after an interval of four days, and finally after an interval of 
eight days. The object sought in adopting this method of dosage 
was to bring the action of the arsenious acid solution and the atoxyl 
at the same time into the circulation, and also it was thought 
probable that, by administering arsenic at one time in form of drench 
and at another time in form of bolus, the gastric symptoms of arsenical 
poisoning would be less likely to occur and the drug would be better 
tolerated. 
In a number of experiments we found that arsenious acid given in 
drench or bolus at a period of paroxysm freed the blood from trypano¬ 
somes in about 24 hours. 
Atoxyl, subcutaneously, cleared the circulation in six to eight hours. 
Consequently, in these experiments, the atoxyl was injected 16 hours 
after the dose of arsenious acid. 
