30 PRESIDENTIAL ADDRESS. 
From the summary that I have given, it will be seen 
that the life history of O. gibsoni is still unknown and there 
is little, as yet, to indicate in what direction we should look 
for the transmitting agent. Probability still favours a 
biting fly, as I pointed out in 1911, though McEachran 
and Hill’s evidence is opposed to such a view. 
The most important additions to our knowledge in 
this connection are (1) the presence of embryos just below 
the skin (Cleland) ; and (2) the fact that they can and do 
escape through the skin when the latter is intact (Nicoll). 
In Breinl’s experiments there was a possibility of 
injury to the overlying skin being caused by scraping 
and thus allowing the embryos to escape. 
Until we know the transmitting agent we cannot 
hope to control the parasite. 
In concluding this portion of my address, I take the 
opportunity to express my appreciation of the work done 
by our Hon. Secretary and Editor, Mr. A. B. Walkom, 
B.Sc. The thanks of the Society are due to him for 
efficient services ungrudgingly rendered, and also to our 
Hon. Librarian, Mr. C. D. Gillies, B.Sc., who has devoted 
a great deal of time to the work of our Society. 
