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A female C. mosquito is placed in an empty bottle connected with an 

 aneroid barometer, and a suction flask raised to a proper height : 



At rarefied pressures corresponding to 2000 or 3000 feet, the insect 

 becomes at first unable to fly, but if withdrawn will bite and draw blood 

 after a while. 



At rarefied pressures corresponding to 4000 or 6000 feet, the general 

 effects are more marked, but the insect does not die, and seems even to 

 get accustomed to the new state of things; but when withdrawn continues 

 weak, and unable to sting for several hours. 



We are thereby led to infer that the C. mosquito, when suddenly 

 transferred to heights above 3000 or 4000 feet, must find it difficult to 

 exert its functions, and that it would never, of its own accord, seek 

 elevations which render its flight difficult. This conclusion agrees, 

 moreover, with the remarks of Baron von. Humboldt, who carefully observed 

 the mosquitoes of Central America. 



From the above experiments it is inferred that the limits of functional 

 activity for the C. mosquito are : as regards temperature, between 60° and 

 100° F., the insect reviving, however, after having been chilled to near 32° 

 F., or warmed to 105° F. ; as regards altitude, from the level of the sea to 

 3000 or 4000 feet. Now the limits which most observers assign to the 

 propagation of yellow fever are temperatures ranging from 60° F.. to 90° 

 F. ("Barton's Reports," 1852, pp. xiii. and 283) ; a general temperature of 

 32° F. having, however, proved ineffectual to prevent the recurrence of the 

 disease (in the case of the "Plymouth"), when a tropical temperature was 

 produced. As regards altitudes, the highest limit at which it has been 

 observed seems to be 4000 feet above the level of the sea. 



Before dismissing the subject under consideration, I must add that 

 the mosquito finds within the precincts of a dwelling all the requirements 

 for its development, growth, and reproduction; dark corners to hide in, 

 stagnant water in which to lay its eggs and develop its larvae, and 

 substances for the female insect to feed on, being the principal conditions. 

 A forgotten tub, or pool of stagnant water in a back yard or garden, is 

 often chosen by the insects as a place of rendezvous where they congregate 

 and lay their eggs; the larvae, in the meantime, going through their 

 successive stages of development. The mother insect when about to die, has 

 been observed to resort to the water where its larvae are growing, its 

 cadaver remaining floating upon the liquid surface. The nocturnal species 

 will naturally lead a more stationary existence than the diurnal ; for the 

 latter, in trying to sting during the busy hours of the day, will often have 

 to follow its intended victim from house to house, returning again and 

 again after being driven off, until it succeeds in planting its sting and 

 filling with blood. Wherever the bite happens to have been successful, there 

 the mosquito will, in all likelihood, take up its quarters; it will develop a 



