DEPOSITIONS OF EGGS. 



95 



reason for this is, that the female of this motii 

 havini^ only the rudiments of vving-s, a peculiarity 

 remarkable in several other moths, she cannot shift 

 so readily about. But whatever may be the real 

 cause, there can be no doubt that the web serves to 

 keep the eg-gs warm during winter ; for though they 

 are placed on the outside of the web, the whole is 

 usually under some projection of a wall or arm of a 

 tree, and the non-conducting property of the silk, 

 both with regard to heat and electricity, must be of 

 great benefit to the eggs in preserving them in an 

 equable temperature, and of course promoting their 

 early hatching. 



"^'ii^M^-' 



Vapourer-moth {Orgym antiqua'), male and female, the latter 

 without wings; with the eggs laid upon the silken cocoon from 

 which the mother has issued. 



We cannot better conclude these imperfect sketches 

 of the hybernation of insect eggs, than by an ac- 

 count of the ingenious experiments made by 

 Spallanzani and John Hunter, by exposing several 

 species of these to great degrees of cold as well 

 as of heat. It results from these experiments that 

 " intense cold," to use the words of Spallanzani, 

 '• does not destroy the eggs of insects." The year 

 1709, when Fahrenheit's thermometer fell to 1° 

 is celebrated for its rigour and its fatal effects on 

 plants and animals. Who can believe, exclaims 

 Boerhaave, that the severity of this winter did not 

 destroy the eggs of insects, especially those exposeil 

 to its iniluenre- in the open fields, on the naked 



