17 
will exist in the absence of free water for a much longer period than 
is really the case. In the opinion of the writer, where the mud dries 
up entirely the mosquito larvee are necessarily killed, but that they 
may exist in very wet mud for a longer or shorter time is true. 
An interesting observation bearing upon this point has been made 
by Dr. St. George Gray, of Castries, St. Lucia, British West Indies, 
and reported in the Journal of Tropical Medicine, London, May 15, 
1900. He says that on February 7, 1900, he examined a spot where he 
had obtained larve of Anopheles a few months before. The pool had 
been dry for three weeks, hardly any rain having fallen during that 
time. The surface of the mud at the bottom was cracked and dry, 
although soft enough under the crust. He put the mud into a clean 
pickle bottle and put about 3 inches of filtered water over it, but there 
was no result. He also took some grass from the sides of the pool and 
put that grass into another pickle bottle, adding 3 inches of filtered 
water. On the following morning he found a few minute larvee 
wriggling about in this bottle. These rapidly grew in size, and he 
soon hada half dozen healthy looking larvee in his bottle. On the 2ist, 
a fortnight after he had taken the grass from the sides of the pool, he 
reared the imago of Culex teniatus. From this observation he argues 
that some species of Culex, at any rate, do not always lay their eggs 
on the surface of the water, but where they will be washed into the 
pool by the first heavy rain. Other similar experiments were failures. 
This record is a very interesting one, but, like all isolated observations, 
needs verification." It may here be mentioned that Drs. J. W. W. 
Stephens and S. R. Christophers, in their article on ‘* The distribution 
of Anopheles in Sierra Leone,” published in the reports of the malarial 
committee to the Royal Society (London, July 6, 1900), stated that 
they were unable to hatch the eggs of Anopheles after desiccation on 
blotting paper for more than forty-eight hours, although they hatched 
after twenty-four and forty-eight hours’ drying, respectively. 
The number of species af mosquitoes.—As regards the different kinds 
of mosquitoes, about 250 species are known, of which only about 30 
have been found in the United States. These are divided into 5 differ- 
ent genera, each of which will receive consideration in the following 
pages. Of the malarial genus Anopheles, Mr. F. V. Theobald writes 
us there are 27 species in the British Museum collection. 
MOSQUITOES AND MALARIA. 
This is not the place to discuss at length the history of the discover- 
ies which have brought about the very perfect proof that mosquitoes 
may and do transfer the malaria germ from a malaria patient and 
‘Dr. Walter Reed, U. S. A., tells me that Dr. Lazear has just made a similar 
observation in Cuba. 
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