OF NATURAL HISTORY. S37 



mentioned. But, as this fubftance is gradually devoured by 

 the worm, the fpace in the cell neceflarily enlarges in propor- 

 tion to the growth and magnitude of the animal. 



We are informed by M. de Reaumur*, that Mr. Pitot 

 furnifhed him with a piece of wood, not exceeding an inch 

 and a half in diameter, which contained the cells of a wood- 

 piercing bee. He cut ofF as much of the wood as was fufli- 

 cient to expofe two of the cells to view, in each of which 

 was a worm. The aperture he had made, to prevent the in^ 

 juries of the air, he clofed, by pafting on it a bit of glal^. 

 The cells were then almoft entirely filled with pafte. The 

 two v/orms were exceedingly fmall, and, of courfe, occupied 

 but little fpace between the walls of the cells and the mafs of 

 pafte. As the animals increafed in fize, the pafie daily di- 

 minifhed. He began to obferve them on the 12th day of 

 June ; and, on the 27th of the fame month, the pafle in eacli 

 cell was nearly confumed, and the worm, folded in two, occu- 

 pied the greater part of its habitation. On the 2d of July^ 

 the provifions of both worms were entirely exhaufled ; and, 

 befide the worms themfelves, there remained in the cells 

 only a few fmall, black, oblong grains of excrement. Thq 

 five or lix following days they fafted, which feemed to be a 

 neceiliiry abftinence, during which they were greatly agitat- 

 ed. They often bended their bodies, and elevated and de- 

 prefled their heads. Thefe movemtjnts were preparatory tq 

 the great change the animals were about to undergo. Be- 

 tween the 7th and 8th of the fame month, they threw oft 

 their fliins, and were metamorphofed into nymphs. On the 

 30th of July, thefe nymphs were, transformed into flies fimi- 

 lar to their parents. In a range of cells, the worms are of 

 different ages, and, of courfe, of different fizes. Thofe in 

 the lower cells are older than thofe in the fuperior ; be- 

 caufe, after the bee has filled with pafle and enclofed its firf^ 



* Tom. 1 1, page 58. lamo edition. 



