•358 THE PHILOSOPHY 



icell, a confiderable time is requifite to colle£l: proviiions, and 

 to form partitions for every fucceflive and fuperior cell. The 

 former, therefore, muft be transformed into nymphs and 

 flies before the latter. Thefe circumftances are apparently 

 forefeen by the common mother ; for, if the undermoft 

 worm, which is oldeft, and fooneft transformed, were to 

 force its way upward, which it could eafily do, it would not 

 only difturb, but infallibly deftroy all thofe lodged in the fu- 

 perior cells. But Nature has wifely prevented this devafta- 

 tion; for the head of the nymph, andconfequently of thefly, is 

 always placed in a downward dire6lion. Its firfl inftin<Stive 

 movements muft, therefore, be in the famedire£lion. That the 

 young flies may efcape from their refpedtive cells, the moth- 

 er digs a hole at the bottom of the long tube, which makes 

 a communication with the undermoft cell and the open air. 

 Sometimes a fimilar paiTage is made near the middle of the 

 tube. By this contrivance, as all the flies inftin(Slively en- 

 deavour to cut their way downward, they find an eafy and 

 convenient pafl^age ; for they have only to pierce the floor 

 of their cells, which they readily perform with their teeth. 



Another fmall fpecies of folitary bees dig hoks in the 

 earth to make a convenient habitation for their young. 

 Their nefts are compofed of cylindrical cells fixed to one 

 another, and each of them, in figure, r^femblgs a thimble. 

 Their bottom, of courfe, is convex and rounded. Th? bot- 

 tom of the fecond is inferted into the entry of the firft ; and 

 the entry of the fecond receives the bottom of the third. 

 They are not all of the fame length. Some of them are five 

 lines long, others only four, and their diameters feldom ex- 

 ceed two lines. Sometimes only two of thefe cells are join- 

 ed together ; and, at other times, we find three or four, 

 which form a kind of cylinder. This cylinder is compofed 

 pi alternate bands of two difl'erent colours : Thofe of the 



