60 TREATISE ON THE! 
by which they are guided ; for as they clus- 
ter closely in those parts of the comb which 
are filled with brood, in order to concentrate 
the heat for their being hatched, the heat 
will of course penetrate to the other side, and 
some portion of it would be wasted if the 
cells on that side were either empty or filled 
only with honey. But when both sides are 
filled with brood, and covered with hive 
Bees, the heat is confined to the spot where 
it is necessary, and is turned to full account 
in bringing the young to maturity. 
The mutual aversion of queens is a stri- 
king feature in the natural history_of this in- 
sect; and though not perhaps strictly in 
place, one extraordinary effect of it may be 
mentioned here. ‘Their mutual enmity may 
be truly saia to be an inborn disposition with 
them, for no sooner has the first of the race 
in a hive about to throw off a second swarm, 
escaped from her own cradle, than she hur- 
ries away in search of those of her rivals, 
and, as will be afterwards described, exerts 
herself with the most impetuous eagerness to 
