174 Timehri. 
into the skin and introduces a poison which has properties akin to that of 
snake venom. The agents of the yellow fever infection are of various 
species—Zancudo bobo with the striped legs may be regarded as the house- 
haunting kind.” 
_ An ExpLopep THrory. 
With regard to the old-fashioned argumentthat malaria is caused by marshes 
and not by mosquitoes, often advanced hy people who are ignorant of the true 
facts, there is absolutely no proof whatever in support of this theory. It has 
been investigated time after time and is now thoroughly exploded, and even 
so far back as 1871, Beauperthuy states “marshes do not communicate to the 
atmosphere anything more than humidity, and the small amount of hydrogen 
they give off does not cause in man the slightest indisposition in equatorial 
and inter-tropical regions renowned for their unhealthiness, nor is it the putres- 
cence of the water that makes it unhealthy, but the presence of mosquitoes.” 
So far back as 1852 Surgeon General Daniel Blair writes in reference tu 
yellow fever in British Guiana ; “ Its shifting lines and gyratory movements 
suggest . . . . the attributes of insect life.” 
i could quote many other references and examples, hundreds in fact, but have 
selected the two foregoing, as the observations on which they were based were 
made here in British Guiana. Time will not permit me to go into details as 
to the proof of the mosquito carrying various infections, but allow me to assure 
you that this has been definitely and conclusively proved. 
The practical results worked out so far are :—anophelene mosquitoes carry 
malsria, culex mosquitoes carry filariasis, stegomyia mosquitoes carry filariasis 
and yellow fever. 
These are the diseases with which we are concerned here in British Guiana, 
but it may be as well to add a few facts that have been demonstrated in 
other paits of the world in relation to blood-sucking insects ana disease ; for example, 
culex mosquitoes carry dengue ; the rat flea, culex cheopis, carries plague ; 
the glossina, a biting fly, sleeping sickness; ticks, relapsing fever; 
sandflies, pellagra ; and midges, Malta (three-day) fever. The bug carries Kala 
Azar and house-flies have been proved to transmit typhoid fever, infantile 
diarrhoea, and anthrax. 
Every year we are adding to our knowledge on this subject, and it all tends 
to the same result, which can be summed up briefly as “ Any insect that bites 
is not only a nuisance, but dangerous to life.” And personally I am a bit of a 
sceptic when people say only one species carzies one disease, I believe that as 
our knowledge increases it will be shown that many diseases are interchange- 
able, for example, the stegomyia mosquito carries yellow fever and filariasis 
also. 
Of all diseases malaria is the most widely spread. It strikes down not only 
the native population, but the pioneers of civilisation, the trader, the planter, 
the missionary, and the soldier, and is the greatest ally of ignorance, prejudice, 
ed 
