52,8 THE GAO FHT. 
where they can find fuitable food, and neceflary warmth. 
The young of certain flies are only capable of fubflfting 
below ground, and of deriving food from a certain flower, 
the narcifius. The mothers of thefe depofit their eggs in 
the roots of that plant. Other flies enter the anus of a 
horfe, becaufe their young are only capable of fubflfting 
in the entrails of that animal, where they remain till 
they are about to be mctamorphofed, and are then eject- 
ed with the dung *. Others are provided with a curious 
indrument, by which they perforate the hides of cattle ; 
and in each hole thus made, they depofit an egg. 
Each of thefe worms, after being hatched, finds itfelf 
furrounded with its proper food, among which it grows ; 
and the cell increates in fize at the fame time, till it 
fometimes reaches the bulk of an egg. The wound be- 
comes filled with purulent matter ; and the opening 
from which it runs ferve3 to fupply the infect with air. 
After the worm has grown there to its full fize, it needs 
a place more dry, and of lefs heat, for its metamorphofis j 
it then drops from the orifice of the wound, and betakes 
itfelf to fome hole, or other retreat, where it is tranf- 
formed. 
An inftin£t as fingular as any of the former is that by 
which fome flies are directed to the nofe of a fheep, a 
goat, or a deer, to lay its eggs* It is in the frontal finus 
of thefe large animals, that she worms produced by thefe 
eggs are deitined to fearch for the only food capable of 
fupporting them. Some of thefe worms, after being 
ejected from this ftrange nidus, become covered with a 
hard Aiell, in which their laft change is completed. Na- 
ture, which provides for every exigence, has furmihed 
this 
* Reaumar, Tome IV. Mem. xii. 
