Mosquitoes as Disease-Carriers. 89 
this, Dr. Nuttall writes * : “ The experiments being made in a 
country where the disease is endemic makes any conclusions 
impossible regarding the reaction fever following on the mosquito- 
bites being due to the inoculation ; it is probably simply a matter 
of coincidence.” 
Further observations on this subject are now being made and 
experiments conducted in a special laboratory in Cuba by the 
American authorities, which will probably show us that the 
older observations of Finlay are correct. Fresh interest was 
aroused in the mosquito theory and yellow fever by a paper read 
at a recent meeting of the American Public Health Association, 
at Indianapolis, by Surgeon Walter Reed and others. From 
experiments and observations made in Cuba, in the course of 
which Dr. Lazear died from yellow fever, apparently conveyed to 
him by an infected mosquito, the following conclusion is arrived 
at: “ The mosquito serves as the intermediate host for the 
parasite of yellow fever, and it is highly probable that the disease 
is only propagated through the bite of this insect.” I have 
heard since this first went to press that Stegomyia fasciata has 
been shown to be the host of the yellow-fever parasite. 
Besides the above diseases in man and the disease in birds, 
which are clearly traced to mosquitoes, it is probable that these 
pests may carry other diseases. Major T. Birt writes from 
Gibraltar as follows : “ The grey-legged mosquitoes {C. pipiens, 
Linn.) are prevalent day and night. The dove-coloured ones 
(0. spathipnlp's, Rond.) only at sunset, night, and sunrise. I 
have found in both species a micrococcus much resembling that 
of Mediterranean fever, and a bacillus much like that of typhoid. 
In the ‘ grey leg ’ the micrococci are far more numerous than the 
bacilli; in the ‘ dove ’ the latter predominate, also amoebae and 
larger bacilli (putrefactive ?); they are frequently found in water- 
closets.” 
The excreta of various insects feeding on cholera and plague 
germs has been found to be infected, and it is not improbable 
that many bacteria are carried by mosquitoes and passed into 
another individual. (Vide Nuttall’s paper on “ The Part played 
by Insects, &c., in the Propagation of Infective Diseases of Man 
and Animals.” j) 
The canine blood worm, Filaria immitis, has also been 
* Johns Hopkins’ Hospital Reports, vol. viii. p. 26. 
f “British Medical Journal,” September 9, 1899. 
