E. Hindle 
199 
Opsonins are also developed in very small quantities but the 
amount of phagocytosis that takes place either in vivo or in vitro is 
insignificant. 
In connection with the immunity reactions of S. duttoni it may be 
of interest to mention Trautmann’s (1907) observations on the effect of 
spirochaetal infections on the course of the disease of trypanosomiasis. 
He found that when animals infected with Trypanosoma brucei, lewisi, 
equiperdum, and gambiense respectively, were afterwards inoculated with 
S. duttoni, the latter caused the trypanosomes to diminish in number, 
and often to disappear from the circulation for some time, and 
consequently the life of the animal was prolonged considerably. 
Tedeschi (1910) was unable to notice any effect of S. duttoni on the 
course of the disease in the case of rats infected with T. brucei and 
T. lewisi respectively, and consequently throws some doubt on Trautmann’s 
observations. 
Recently I have made some observations on the effect of an infection 
of S. duttoni on T. brucei and T. gambiense, I’espectively, in mice, and find 
that the appearance of spirochaetes in the circulation is followed by a 
diminution in the number of trypanosomes and often the latter disappear 
for a few days. As a result the length of life of the mice was consider¬ 
ably prolonged in the case of those with a mixed infection, when 
compared with mice infected with either T. brucei or T. gambiense 
alone. These results, therefore, confirm Trautmann’s observations. 
In conclusion a few words may be added on the present method of 
distinguishing spirochaetes by their immunity reactions alone. 
Darling’s observations, mentioned above, show that it is impossible 
to distinguish them by this method, for in the case of the parasite of 
Panama Relapsing Fever the spirochaetes from different individuals 
gave different immunity reactions. Moreover, Manteufel (1908) showed 
that a particular strain of spirochaetes may become weakened by passage 
through a series of animals, and then differ in its immunity reactions 
from the original strain. 
It is important to remember that the morphological differences 
between the variou.s species of blood spirochaetes are insignificant, and 
at present they are almost entirely distinguished by means of their 
immunity reactions. Manteufel (1908) and Neumann (1909) have 
shown that N recurrentis and novyi, as well as duttoni, may be trans¬ 
mitted by 0. moubata, and therefore it is impossible to distinguish 
them by the mode of transmission. 
