65 
is bordered by swampy plains some miles in width, so that the 
conditions are unfavourable for this fly. On the Belgian side, this 
does not obtain to such an extent, so that the fly is probably present, 
although I have no definite knowledge as to this. Gl. morsitans, 
and possibly the closely related pallidipes and longipalpis, is widely 
spread over the country, however. On the road from Broken Hill 
to Fort Jameson, I found them at one spot in the Machinga Hills, 
from the base of these right across the Luanga to within a day of 
Petauke, and near the Sasare mine. From Fort Jameson to the 
Luapula, they occur from the Luangwa to the base of the Machingas. 
There is a sudden rise here to the plateau of 2,500 feet or so, and on 
top of the hills I did not see fly again until I got to the Kasanka 
river. In this vicinity they are very plentiful, and stretch over to the 
Luapula and up north past Chitambo’s through the country to the 
east of Bangweulu. They may be said to be found in most of the 
Luapula division. 
‘ I have found three cases of sleeping sickness in the course of 
my work, all with a history of having worked in the Katanga mines. 
All had markedly enlarged glands, and, at the time I saw them, 
appeared perfectly healthy. Fly {GL morsilans) was present in the 
village of at least one case. Considering the thousands from this 
country who have worked in the Katanga mines, I am perfectly 
convinced that there are many more cases scattered through North- 
East Rhodesia, as the labour was not drawn from any one particular 
district. 
‘ As you are aware, all the work which has been done goes to 
show that the transmission is mechanical. While I think this is not 
sufficient to account for the rapid spread of the disease in view of 
the great difficulty experienced in getting positive results, it is a fact 
which cannot be too strongly emphasised. There is too great a 
tendency to regard Gl. palpalis as the only infecting agent. That 
this is not so has been shown by the work in Uganda, where successful 
transmission experiments were made with Gl. fusca. Again the work 
on cattle trypanosomes shows that while one or two species are 
normally concerned in the extension of the disease, it is quite possible 
to effect this by the use of not only other species of tsetses but also 
other distinct genera, e.g. Stomoxys and Tabamis. This surely is 
sufficient to demonstrate that, at present, all biting flies, and 
