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 



