3 GO INSECT ARCHITECTURE. 



doubt, not ; but the apertures by which the air is admitted 

 to the inhabitants of the woody gall, although they may 

 escape our notice, in consequence of their minuteness, are 

 not, in fact, less real. We know that, however careful we 

 may be in inserting a cork into a glass, the mercury with 

 which it is filled is not sheltered from the action of the air, 

 which weighs upon the cork ; we know that the air passes 

 through, and acts upon the mercury in the tube. The air 

 can also, in the same way, penetrate through the obstruc- 

 tion of a gall of wood, though it have no perceptible open- 

 ing or crack ; but the air cannot pass in this manner so 

 readily through the skins and membranes of animals. 



In order to see the interior of the cavity of an animal 

 gall, Eeaumur opened several, either with a razor or a pair 

 of scissors ; the operation, however, cannot fail to be pain- 

 ful to the cow, and consequently renders it impatient under 

 the process. The grub being confined in a tolerably large 

 fistulous ulcer, a part of the cavity must necessarily be 

 filled with pus or matter. The bump is a sort of cautery, 

 which has been opened by the insect, as issues are made 

 by caustic : the grub occupies this issue, and prevents it 

 from closing. If the pus or matter which is in the cavity, 

 and that which is daily added, to it, had no means of 

 escaping, each tumor would become a considerable abscess, 

 in which the grub would perish : but the hole of the bump, 

 which admits the entrance of the air, permits the pus or 

 matter to escape ; that pus frequently mats the hairs toge- 

 ther which are above the small holes, and this drying 

 around the holes acquires a consistency, and forms in the 

 interior of the opening a kind of ring. This matter appears 

 to be the only aliment allowed for the grub, for there is no 

 appearance that it lives, like the grubs of flesh-flies, upon 

 putrescent meat. Mandibles, indeed, similar to those with 

 which other grubs break their food, are altogether wanting, 

 A beast which has thirty, forty, or more of these bumps 

 upon its back, would be in a condition of great pain and 

 suffering, terrible indeed in the extreme, if its flesh were 

 torn and devoured by as many large grubs ; but there is 

 every appearance that they do not at all afflict, or only 



