62 AGRICULTURAL EXPERIMENT STATION. 



washed with pure hydrate of calcium. A second jar was treated in the 

 same manner, carbonate of calcium being used in place of the hydrate. The 

 principal part of a freshly-prepared whitewash is a hydrate of calcium, 

 and after it is once spread on walls it undergoes a chemical change, due 

 to moisture and other causes forming carbonate of calcium. Having taken 

 this chemical change into consideration, the inner coating of jar number 

 I represented the coating of a freshly-whitewashed cellar, and that of 

 jar number 2 the coating of a whitewashed cellar not of recent date. Sev- 

 eral mosquitoes were confined in each jar and kept there for over ten days, 

 with the result that only one insect died out of six in jar number 2. The 

 insects confined in jar number i were somewhat inactive, due to the strong 

 odor of the hydrate, whereas those confined in jar number 2 were lively 

 and eager to be taken from their prison. The second theory, the cellar 

 being rendered light by a coat of whitewash, is not a plausible one, the 

 whitewash acting only as a reflecting agent from the light without and, 

 besides that, I have noticed hibernating insects in light places, although, as 

 a rule, they are found in dark corners. 



Respectfully submitted, 



GEORGE J. KELLER. 

 Newark, N. J., April 25th, 1904. 



CHAPTER VI. 



MOSQUITOES AND DISEASE. 



That certain febrile diseases and some others depend upon 

 mosquitoes for their continuance and for their transmission from 

 one individual to another is now generally accepted as proven. 

 So generally, indeed, that preliminary to beginning work on 

 the Panama Canal the engineers in charge have arranged to 

 improve sanitary conditions and lessen the clanger from tropical 

 fevers by draining or otherwise dealing with mosquito breeding 

 localities along the line. Most, if not all, the pernicious "swamp" 

 and "jungle'' fevers are now traced to them with more or less 

 certainty, and the control of the mosquito pest is an accepted 

 principle of sanitary practice. 



Yellow fever, one of the most dreaded diseases of the Soutli- 

 ern States in our own country, has been positively proven to 

 depend upon Stcgoiiiyia fasciata, a mosquito which, fortunately, 

 has not been found in New Jersey. The actual life cycle of the 

 germ or organism causing the disease has not yet been followed 

 out; if, indeed, it is certainly known; but the experimental evi- 

 dence is complete. ■ Other tropical diseases, like filariasis and 

 clep/iaufiasis, are known to be carried by these insects, and their 

 agency in yet others is suspected. 



