558 
THOMPSON YATES LABORATORIES REPORT 
A certain amount of breeding of mosquitoes may occur upon the vessels ; thus 
one captain told me that he once discovered larvae in the water tanks. The telegraph 
ship which has been many years upon the Amazon was examined ; very many 
S.fasciatus and some other gnats were seen and taken. Besides it was found that 
there were abundant larvae of S. fasciatus in the bilge water ; some permanganate of 
potash had been put down with a view of killing them, but the quantity was probably 
much too small and most of it soon decomposed ; the trial of a small quantity of 
kerosene oil was suggested as a more likely means. In vessels such as this which 
remains long on the river as well as those which are only a short time, there ought to 
be provision of netting to fit portholes, doorways, lights, etc., so that at any rate a 
certain amount of protection and comfort might be obtained. 
