MARCH. 
65 
ants become torpid in winter^ and where the climate is not 
cold enough to suspend their animation^ it is probable they 
can always find food throughout this season. 
C. — I have often found ants in a torpid state^ in the trunks 
of trees^ which they have mined into galleries and chambers ; 
but I have never found any store of grain, or other food. 
F. — The chambers of the wood-mining ants, especially 
the large species that we often find in the wood of cedar- 
trees, &c. {Formica Pubescens are very curious : it would 
seem impossible to construct partitions so thin and so smooth, 
with no other instruments than their jaws. They are often 
as thin as paper^ and without any roughness on the surface, 
although generally formed in the soft-timbered trees, which 
do not readily bear a smooth surface. It is effected altoge- 
ther by the tedious process of abrading minute particles by 
means of the jaws ; though by what instinct they ascertain 
when the requisite thinness is attained, we know not. The 
formation of the thin cells of the honeycomb of bees is said to 
proceed on nearly the same principle ; a block or mass of 
wax is first laid down, and the cells are excavated out of it, 
by the jaws of the bees : the walls or partitions being left, 
and the remainder abraded away, and redeposited in another 
place. 
C — What causes the remarkable variegations, of differ- 
ent colours, which mark the barks of many forest trees ? 
F, — They are chiefly owing to parasitic plants of the 
cryptogamous class ; mosses and lichens. The bark of the 
beech and maple, particularly the soft maple, {Acer Ru- 
brum ?) is marked with patches of white and yellow, which 
if we look closely, we shall find to be a thin and papery 
lichen. The loose scales, of which the external bark of the 
spruce is composed, are sometimes spotted with a similar 
substance, perhaps the same species. On the beech and 
