TRYPANOSOMES IN TSETSE-FLIES AND OTHER DIPTERA. 163 
informed, inserted an abstract of it in the ‘Bull. Inst. 
Pasteur. I am indebted to M. Mesnil’s happy indiscretion 
for securing to me the priority of the statement, that the 
“wild” trypanosomes of Glossina palpalis were quite 
distinct from those of sleeping sickness—a conclusion to 
which Novy came independently after studying preparations 
sent him by Gray ; his results were published in a memoir (82), 
in which he named one of the wild species T’. grayi. 
Shortly after this came the appalling news that our 
colleague, Tulloch, had become infected with trypanosomes. 
This most sad event, of course, put an end to further work, 
and Gray returned to England, bringing Tulloch with him. 
We then wrote a preliminary account of our results (29), which, 
so far as poor Tulloch was concerned, was a posthumous 
work when published. Our collaboration then broke up, and 
I began the detailed study of my material, and discovered 
the encystment of T. grayi, a result which I at once com- 
municated to the Royal Society (28). It isa common human 
weakness to attribute failures to bad luck; nevertheless I 
cannot but deeply regret that I did not discover the encyst- 
ment while I was in Entebbe. Had I done so, it would have 
modified the whole course of my researches. The fly in which 
this discovery was made was one of the last examined by me, 
a fortnight before I left off working. As I was then pro- 
fessor at University College, however, it was imperative upon 
me to return to my duties, having already had my leave of 
absence generously extended by the College for an extra 
three months. 
Such is, in brief, the history of the conditions under which 
_these investigations were carried on. It only remains for me 
to perform the pleasant duty of thanking those who have 
helped in my task. To the Tropical Diseases Committee of 
the Royal Society, in the first place, I am mdebted not only 
for sending me to Uganda, but for providing me with assist- 
ance in working through my material after my return. 
Without the help and experienced advice of my colleagues on 
the Commission, Gray and Tulloch, I could have done little. 
