118 A NEW THEORY OF EVOLUTION. 



animal food instead of honey, paralysing 

 without killing its victim, and spinning a 

 cocoon are habits antagonistic to those of 

 the primitive bee, and therefore could not 

 have been inherited, but must have come 

 from some mysterious source from what 

 we call a modification of its Specific life- 

 force. 



Other genera allied to the Sphex display 

 singular modifications of its wonderful in- 

 stincts. 



Thus the Ammophila, after digging a hole, 

 covers the entrance with a small flat stone 

 until it captures and returns with a paralysed 

 caterpillar ; it then removes the stone and 

 drags its victim into its cell. Small cater- 

 pillars are paralysed sufficiently by a single 

 thrust in the middle of the body, but the 

 larger sometimes fifteen times the size of 

 the assailant are stabbed in every segment 

 before they are quiescent enough to do the 

 larva no injury. Like the Sphex, the Am- 

 mophila, after depositing its egg, closes its 

 burrow, and leaves never to return ; but 

 another variety, the Bembex, does not para- 

 lyse the food of its larva, and must in conse- 

 quence return frequently to provide it with 

 fresh meat. The cell is constructed in a slope 

 of loose sand, and, when the insect leaves its 



