GENERATION OF INSECTS. ' 13 



eggs or ovula, of innumerable kinds of animalcules 

 floating by myriads of myriads through the atmo- 

 sphere, so diminutive as to bear no larger proportion 

 to the eggs of the aphis than these bear to those of 

 the wren or the hedge-sparrow; protected at the 

 same time from destruction, by the filmy integument 

 that surrounds them, till they can meet with a proper 

 nest for their reception, and a proper stimulating- 

 power to quicken them into life; and which, with 

 respect to many of them, are only found obvious to the 

 senses in different descriptions of animal fluids.'* 



It appears to us that it can be nothing more than 

 a fancy, which is quite unsupported by evidence, to 

 say that the ejjfr of any species of animalcules or 

 insects float about in the atmosphere; for, independent 

 of their weight, (every known species being greatly 

 heavier than air,) the parent insects of every species 

 whose history has been accurately investigated mani- 

 fest the utmost anxiety to deposit their eggs upon or 

 near the appropriate food of the young. To commit 

 them to the winds would be a complete dereliction of 

 this invariable law of insect economy, But admit- 

 ting for a moment this hypothesis that the eggs of 

 insects are diffused through the atmosphere, the cir- 

 cumstance must be accompanied with two conditions, 

 the eggs must either be dropped by the parents 

 while on the wing, or be carried off by winds from the 

 terrestrial substances upon which they may have been 

 deposited. 



On the supposition that the eggs are dropped by the 

 mother insects while on the wing, we must also admit 

 (for there is no avoiding it) that they continue to 

 float about, unhatched, from the end of the summer 

 till the commencement of spring, at which time only 

 the broods make their appearance. Yet when we 



* Good's Study of Medicine, v. i, p. 339, 3rd edition, Lon- 

 don, 1829. 



VOL. VI. 2 



