16 Col. Sir D. Bruce and others. Zrypanosome [July 22, 
The evidence, therefore, at present points to the Glossina palpalis being 
the carrier of this disease, and that the wild animals living in the fly area 
act as a reservoir of the virus. 
This species of trypanosome is similar to Trypanosoma nanum, in that it 
is only pathogenic to equines and bovines, and has no effect on the smaller 
laboratory animals. There was no opportunity in Uganda of inoculating it 
into horses, mules, or donkeys. 
Nine cattle came under observation suffering from a natural infection of 
the disease. Seven of these died after being at Mpumu, on an average, 
103 days. Five cattle were successfully inoculated, and these died, on an 
average, in 69 days. The disease is, therefore, a fairly rapid and fatal one 
in cattle. It may be noted that two of the cattle (Experiments 493 
and 583), after living for 268 and 237 days respectively, died at last from an 
accidental infection of Zrypanosoma pecorum. It is possible that these two 
oxen had recovered, and if not, it is certain that trypanosomes were either 
absent or very scanty in their blood, as inoculations from them failed to 
infect goats and sheep. It may also be noted that none of the four sheep 
which were inoculated ever showed signs of the disease. This is probably 
due to the scarcity or absence of the trypanosomes in the blood used in the 
experiment for inoculation, and not to any natural immunity. 
MorPHOLOGY OF TRYPANOSOMA VIVAX, 
This species of pathogenic trypanosome can at once be recognised among 
all the others by its shape alone. There is no tendency to dimorphism, as in 
Trypanosoma brucer and Trypanosoma gambrense. On the contrary, the 
individuals tend to run persistently to one type. This type has an average 
length of 24 microns. The body posterior to the nucleus is swollen, and 
contains clear protoplasm, in which an alveolar structure can be made out; 
the posterior end is rounded, as a rule, and close to it is the large round 
micronucleus; the anterior part of the body rapidly narrows and terminates 
in a free flagellum ; the nucleus is elongated and situated in the narrowed 
part,-is often broken up and diffused, and seems to fill up the part 
of the body in which it les; the undulating membrane is narrow and 
simple, and can, as a rule, only be made out by the deeply-stained flagellum 
running along its border. An examination of the plates which illustrate 
this paper will, however, give a clearer idea of the general appearance of this 
species than any written description. — 
