6o ANIMALCUI-A OF INFUSION'S. I. 



I have expofed eggs to a more rigorous trial 

 than the winter 1709. Thofe of feveral infefts 

 and among others of the filk-worm moth, and elm 

 butterfly, were inclofed in a glafs veflfel, and 

 buried five hours in a mixture of ice and fal 

 gem ; the thermometer fell 6° below o. In the 

 middle of the following fpring, however, caterpil- 

 lars came from all the eggs, and at the fame tims 

 as from thofe that had fuffered no coM. 



In the following year, I fubjefted them to an 

 experiment flill more hazardous. A mixture ef 

 ice and fal gem, with the fuming fpirit of nitre, 

 reduced the thermometer 22° below o, that k 

 23^^ lower than in 1709. They were not in- 

 jured, as I had evident proof by their being 

 hatched. 



Combining all thefe fads, we conclude that 

 cold is lefs noxious to germs and eggs than to ani- 

 malcula and infefts. Germs In general can fupport 

 2° below o : whereas of animaleula, fome die 

 at freezing, and fome about 2c°. The eggs of 

 many infecls continue fertile at 22° below o, 

 while the infeds die at 16^^ and .14°. This I 

 have feen in fiik-moths eggs, and thofe of the elm 

 butterfly ; and although there are caterpillars 

 and chryfalids able to refift great cold, 1 have 

 uniformly found it to be in a lefs degree than 

 their eggs. What can be the caufe of fuch a 

 difference ? The queftion has already been agi- 

 tated when fpeaking of heat j and in the fame 



manneir 



