266 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 14 



constant temperature of 80° Fahr., he determined to secure data on 

 saturated aqueous solutions of various salts at that temperature. Ac- 

 cordingly a chemist was secured to make the determinations. 



Data were obtained on the following salts:- sodium chloride, so- 

 dium bromide, barium chloride, lithium chloride, potassium sulphate, 

 calciimi chloride, aluminum chloride, potassitim chromate, copper 

 nitrate, soditmi phosphate, sodium nitrate, sodium hydroxide and 

 strontium chloride. With this at hand he selected from the group the 

 following salts:- lithitim chloride giving 7.1% atmospheric moisture: 

 calcium chloride giving 25.9%; sodium hydroxide giving 30.7%; altmi- 

 inum chloride giving 37%; copper nitrate giving 45.7%; sodium brom- 

 ide giving 56.1%; sodium chloride giving 73.4%; sodium nitrate giv- 

 ing 80% and potassium sulphate giving 89.7%. The air as it came 

 directly from the concentrated sulphuric acid drier contained less than 

 1% of atmospheric moisture, and the air which was passed through 

 distilled water contained approximately 100% atmospheric moisture. 



The length of time necessary for certain transformations to take 

 place was adopted as the measure of the response of the bean weevil 

 to these varying percentages of atmospheric moisture. It was thought 

 to be impracticable to check this type of measure by the measurement 

 of the evolution of carbon dioxide, because the food of the insect, being 

 a living plant, threw off considerable quantities of carbon dioxide on 

 its own account and obscured the evolution of that gas from the in- 

 sects under observation. 



Two curves were derived; the first representing the period of time 

 from the laying of the egg to the formation of the pupa, and the sec- 

 ond representing the period of time from the laying of the egg to the 

 emergence of the adult. The first curve has proven to be ver}'- smooth 

 and definite, while the second curve shows ver}^ pronounced variations. 

 No individuals succeeded in reaching maturity in an atmospheric mois - 

 ture of less than 1%, and very few individuals succeeded in an atmos- 

 pheric moisture of 7.1%. Comparatively few succeeded in reaching 

 maturity in an atmospheric moisture of 25.9%. In these three cas- 

 es the only apparent cause was the low atmospheric humidity. In 

 both 89.7% and approximately 100% in spite of everj^thing that could 

 be done in the way of sterilising the food, fungi developed and always 

 greatly reduced the number, and in some cases, utterly prevented the 

 insects from reaching maturity. Such as did reach maturity in the 



