710 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1909. 
in Transvaal cattle the “ galziekte;” Trypanosoma transvaliense, of 
South African cattle; Trypanosoma dimorphon, of Gambian horses; 
Trypanosoma nanum, of the Soudanese cattle. The greater part of 
these parasites are transmitted by the bites of insects. 
The 7’. brucei of “nagana” is inoculated by the redoubtable flies 
known in the country in which they are found by the name of “ tsetse,” 
but of which the scientific name is Glossina. <A little larger than our 
common fly, Afusca domestica, these tsetses are known by their 
enormous proboscis, which is longer than the head and is placed in 
prolongation of the axis of the body, as well as by their wings, which 
are twice as large as the abdomen. (fig. 6). 
These insects, of which eight species have been described, are 
peculiar to tropical Africa, where they abound in forests located 
near water (streams, marshes, ponds, etc.), and where they remain 
concealed in the shade of trees and shrubbery, preferring certain 
kinds, such as the mimosa, for example. Eager 
for blood, they seize upon men and animals, which 
during the day traverse these wooded regions, and 
bite them unmercifully. These tsetses are an ob- 
ject of terror to the natives, and in fact they con- 
stitute one of the most serious scourges of the 
African tropical zone. All the explorers of the 
country, and Livingston in particular, have agreed 
in declaring that it was impossible to traverse a 
tsetse country, because the energies of men and 
oe eee beasts are destroyed almost certainly by most epi- 
tans X 24. After zootics due to the bites of these Diptera. This 
Bruce & Pre suffices to show that the Glossina renders vast ter- 
ritories of Africa absolutely uninhabitable for 
cattle, and hence unsuitable for colonization, which are otherwise 
fertile and well-watered, and have a mild climate. 
For a long time the nature of this inoculated disease was unknown. 
It was said that the tsetses were dangerous because of a poison which 
they secreted, but no one was able to isolate this-poison. It was also 
said that the tsetses were dangerous because they inoculated a bac- 
terial virus, and charbon was spoken of. As in the case of malaria, 
there is nothing true in all this. It is known to-day, thanks to those 
memorable researches, the remembrance of which brings to my lips 
the name of the man who was the chief investigator, Bruce, that the 
tsetses are dangerous not because of a virus, or of bacteria, but of 
trypanosomes. To man they give the 7rypanosoma gambiense, which 
is conveyed by a particular species, the Glossina palpalis; in animals 
they inoculate the 7vypanosoma brucei, which is carried by all the 
other species of Glossina, notably by G. morsitans, pallidipes, and 
longipennis. 
