ANIMAL-GALLS. 411 



bovis, Lath.) is hatched, it immediately (if Mr. 

 Bracey Clark be correct) burrows into the skin; 

 while, according to Reaumur, it is hatched there. 

 At all events, the grub is found in a bump on the 

 animal's back, resembling a gall on a tree,— "a 

 place," says Re'aumur, "where food is found in 

 abundance, where it is protected from the weather, 

 where it enjoys at all times an equal degree of 

 warmth, and where it finally attains maturity. 

 When in an advanced stage, the bumps appear much 

 like the swellings produced upon the forehead by a 

 smart blow. These, with the grubs, are represented 

 in the foregoing figure, and also at page 412. 



Every bump, according to Re'aumur, has m its 

 inside a cavity, which is a lodging proportionate to 

 the size of the insect. The bump and cavity also 

 increase in proportion to the growth of the grub. It 

 is not until about the middle of May that these bumps 

 can be seen full grown. Owing to particular cir- 

 cumstances, they do not all attain an equal size. 1 lie 

 largest of them are sixteen or seventeen lines in dia- 

 meter at their base, and about an inch high ; but they 



$2^ jjftffliii 



Fly, maggot, and grub of the Ox-breeze-fly, with a microscopic 

 view of the maggot. 



* Mem. iv. 540. 



