W. F. Cooper and H. E. Laws 
205 
Dipping in Relation to Trypanosomiasis. 
If by dipping, the amount of arsenic which can be introduced into 
the peripheral cutaneous vessels is sufficient to kill ticks, then it is 
reasonable to imagine that it might also kill other blood-sucking pests, 
such as Tsetse flies; also the natural infection of stock by Tsetse flies 
should be preventible by the same means. 
Regarding the effect of dipping on biting flies, the fact that the 
latter feed so rapidly, in comparison with the very slow rate of feeding 
of the tick, introduces a possible difficulty, but experiments are now 
being carried out by one of us (W. F. C.) in the Congo, to test this point. 
With regard to trypanosomiasis it is highly probable that dipping 
would exert a pronounced effect. In the experimental treatment of 
trypanosomiasis, it has been shown repeatedly that arsenious acid, 
administered per os, is very effective, but the effect is not permanent 
because it is impossible to prolong the treatment without producing 
symptoms of arsenical poisoning and the ultimate death of the host. 
But dipping furnishes a method of applying arsenic in comparatively 
large doses at frequent intervals without deleterious effects on the 
treated animal, and there is reason to believe that its use in this manner 
would exert a remedial as well as a prophylactic effect. 
The whole point has been considered in connection with some 
preliminary investigations on Nagana-infected dogs carried out by one 
of the authors (W. F. C.) in collaboration with Dr E. Hindle and 
Mr L. E. Robinson, at Cambridge, which form the subject of a paper 
now in course of preparation for the press. 
