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A. A square wooden box, well ventilated, with fine crinoline 
gauze screening on two sides and glass on the other two sides, with 
a central replaceable partition, covered with No. 16 mesh wire 
screening, was constructed. Several dozen mosquitos at a time, of 
the above species were liberated on one side of the partition without 
food or water, and on the opposite side, close to the screen partition, 
were placed water, banana, candy, sugar and raisins as bait. Only 
three mosquitos out of several hundreds of several varieties passed 
through the No. 16 mesh partition under the conditions of the experi¬ 
ment. As the space including the mosquitos was about one-half of a 
cubic foot in volume, and as there were a few recesses in which the 
mosquitos could hide, an electric light bulb was hung in such a 
position at night that the mosquitos would be attracted by it, but this 
did not favour the passage of mosquitos through the screen. Tobacco 
fumes were passed into the mosquito compartment with a rubber bulb 
apparatus, and while this excited the mosquitos, did not cause any 
of them to escape through the screen. When a persons arm was 
introduced into the compartment close to the No. 16 mesh wire 
partition it did not induce the mosquitos to escape through the 
screening. 
B. Next a lantern-chimney, covered on one side with fine mesh 
crinoline gauze and on the other side with a metal collar holding in 
place a piece of the No. 16 mesh wire screening, was partly filled 
with various mosquitos and placed near the same bait as before under 
a large glass bell jar. Eighteen mosquitos escaped from the chimney 
through the No. 16 mesh screening into the surrounding jar. The 
closer quarters and the absence of resting places in the chimney 
evidently favoured the escape of mosquitos through the wire 
screening. On one occasion, by passing a gust of air through the 
lantern chimney jar, a male Culex was helped through and escaped. 
The conditions in the experiments were all rigid and more extreme 
than those under actual conditions where mosquitos are trying to 
enter a screened house from the open. 
The chemical composition of various screening material used was 
investigated by Dr. R. W. Nauss, formerly of this Laboratory. 
Screening of excellent quality was compared with that which had 
deteriorated more or less rapidly, and analyses of screens and then- 
incrustations made to determine the factors concerned in its corrosion. 
