1 5° First Report on Economic Zoology. 
Nairobi, 
East Africa Protectorate, 
3rd September , 1901. 
To Sir Charles Eliot, K.C.M.G., C.B., 
His Majesty’s Commissioner and Consul General, Mombasa. 
Sir, — I beg to acknowledge receipt of a copy of the correspondence 
re Tsetse-fly and the preservation of the Buffalo which you forwarded to 
me for my opinion, and I have the honour to transmit to you herewith my 
observations on the subject. 
The Tsetse-fly belt of British East Africa, exclusive of Jubaland, may 
be said to extend from Mtoto Andes to Simlia, a distance of roughly ninety 
miles ; it is situated in a densely wooded, low-lying part of the country, 
about 3000 feet to 3f00 feet above sea level. 
Driajani, an old camping ground, within this area, was considered by 
the late Captain Haslam and myself to be the most dangerous place for fly, 
on the old transport route, but strange to say it was practically devoid of 
game of any kind. 
In my opinion, Buffalo and other big game are not the only factors in 
the Tsetse-fly theory, and we must first consider the question of climate 
and humidity before we condemn the Bos caffci as the true and only source 
of the Tsetse-fly and Tsetse-fly disease. 
I believe that the distribution of the fly is entirely influenced by the 
physical aspects of the country and that for its existence it must have a 
humid, low-lying position. 
Major Bruce in his excellent report says (see p. 20. Further report 
on Tsetse-fly disease in Zululand, 1896), “ That the presence of wild 
animals in the vicinity of horses and oxen is not the only factor in the 
problem is shown by the fact that in the old days when big game was 
numerous and roamed over the whole country, hunters and travellers 
never complained of fly until they encountered the disease in low-lying 
tracts of country or along the large river valleys.” 
As in the Hermansdorp district of Cape Colony herds of Buffalo are 
still to be found, yet Tsetse-fly with its concomitant disease is unknown, 
so in the high altitude of the Kedong (6000 feet), in this Protectorate, 
herds of Buffalo are to be met with, greatly reduced in numbers by rinder- 
pest within recent years it is true, yet neither Tsetse-fly nor Tsetse-fly 
disease have ever been known to occur, nor has the fly or its disease been 
heard of in the Baringo district of the Uganda Protectorate, where herds 
of Buffalo and other big game exist. 
When studying the causes which rendered the Island of Mombasa 
uninhabitable for horses, I ascertained that an organism, the morphology 
of which was identical with that found in animals suffering from Tsetse-fly 
disease, was found in donkeys which had never left the island. 
I expressed an opinion then ( vide Preliminary Report as to the causes 
which rendered the Island of Mombasa uninhabitable for horses in 1899) 
with regard to African Nagana and Indian Surra being one and the same 
disease, and as the occurrence of Surra cannot be attributed to the presence 
of wild animals or Tsetse-fly, we must explain, ere we destroy the buffalo 
in an attempt to stamp out Nagana, why a disease identical with that 
