80 
Surra 
The same condition is observed when arsenic, in large doses, is 
administered subcutaneously or intravenously. 
Both atoxyl and arsenic, when given in bolus, produce death more 
rapidly than when administered hypodermically. The lesions, in this 
case, are found in the stomach and intestines. 
In several experiments, where atoxyl and arsenious acid were given 
at the same time, their toxic effects w'ere undoubtedly combined. Ponies, 
about 250 lbs. w'eight, which could tolerate 1 gramme of arsenious acid 
and 50 c.c, of 4°/ 0 atoxyl, w'hen administered on separate days, showed 
symptoms of colic, dullness and loss of appetite when 05 gramme of 
arsenious acid was combined with the full dose of atoxyl. 
(5) Our imperfect knowledge of the life cycle of the trypanosomes 
in the body is one of the difficulties in the problem of the treatment of 
the disease. The periodic appearance and disappearance of the trypano¬ 
somes in the circulation and the existence and location of the parasite 
during the intermission period are, as yet, insufficiently explained. The 
more generally accepted hypothesis, regarding the evolution of the 
trypanosomes in the body, appears to be that they multiply principally 
by longitudinal divisions, that a toxin, produced during the periods of 
paroxysm, is destructive to the majority of the mature parasites and that, 
during the period of intermission, the survivors multiply by division in 
the glands and organs. 
In a paper, dealing with the evolution of the surra parasite (1904), I 
suggested that, after the breaking up of the parasites in the blood stream, 
the nucleus was capable of reforming into a new individual and depicted 
forms which appeared to be undergoing this process. 
Breinl and Salvin Moore (1908) describe somewhat similar latent 
bodies which they found became encysted in the liver cells. 
This hypothesis appears to be more in accordance with clinical 
observations and supplies a better explanation of the periods of paroxysm 
and intermission. At a paroxysm the parasites continue to increase in 
the blood for one, two or three days. If this increase was due to rapid 
division of the trypanosomes, one v'ould expect this process to be most 
marked in the blood during the early part of this period. This is uot 
the case. The time, when multiplication forms are most noticeable in 
the blood, is when the paroxysm is at its height and just preceding the 
downward curve. This, probably, indicates that the division process is 
an emergency method of multiplication called forth by products in the 
blood adverse to the life of the parasite. These new' individuals, as well 
as the parent stock, become disintegrated to a certain extent and lose 
