i. r, ei'aitsi tjroup, which includes hriicci and T. sitdancnsc? 
The validity of T. brucei, save on the grounds of cross-iiioculationj 
IS open to question, unless it be prc-surmised that each species of 
trypanosome has its own particular genus or species of biting fly to 
bring about dissemination. In Africa, where both 'I . brucci and 
r. aansi occur, it has become usual to refer to Glossina and 
Tabanidae as the respective transmitters. In the same manner an 
nansi-hke organism, which in nature is supposedly spread by 
Glossina, or which is met with in cases of ‘ tsetse-fly disease,’ is 
referred to as Trypanosoma brucei. This, we take it, implies the 
acceptance of T. brucei as the local type of the evansi group, and we 
consequently assigned to it our dog trypanosome. But it is no more 
possible to distinguish between T. raansi and 7 . brucei in t c e , 
unless the supposed transmitting factor be considered, than it is to 
differentiate T. ei’ansi and T. sudanense. 
2. T. dimorphon group, including 7 . congolcnse^ and 7 . petandi. 
In their action on laboratory animals these three 
very closely; and in their morphology, as shown in staine m y 
method), T. congolense is almost identical with the T. ditnorp on a 
Paris. Writing on the subject of these two, Martin. Leboeuf and 
Roubauds hold that in the French Congo the latter is more active 
moving more readily across the field and producing 
lateral displacement of the corpuscles ; and they coiiten i 
experience will enable an observer to distinguish between 
Assuming that these two species are distinct, based on tie s rai 
Europe, it is not to be forgotten that in countries sue as 
Africa, where mixed infections are not unknown, they g 
conceivably both occur in the same host, and here more esp 
since the geographical distributions coincide. 
T. pecaudi appears to have more claim to recognition m the n ■ 
Morphologically, the similarity between it and T. imor ^ 
»lthough it has been noted that the ' short ’ form of . p ^ 
attain a greater breadth and carry a slightly better devetoped 
undulating membrane than is usual in the type strain, an ^ 
are present at the same time. I-averan a however, 
morphological differences do not suffice to diffeien 
