Animal Galls. 435 



grub of the breeze-flies in a flesh-gall ? Without doubt, not ; 

 but the apertures by which the air is admitted to the inhabit- 

 ants 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 obstruction of a gall of wood, though 

 it have no perceptible opening or crack ; but the air cannot 

 pass in this manner so readily through the skins and mem- 

 branes of animals. 



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

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

 of scissors ; the operation, however, cannot fail to be painful 

 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 together 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 



