The Anthrax 



comes away all the same, atom by atom. At 

 long intervals, the method changes. With its 

 crown of awls driven into the pith, the animal 

 frets and fidgets, sways on the pivot of its 

 anal armour. The work of the auger follows 

 that of the pick-axe. Then the blows recom- 

 mence, interspersed with periods of rest to 

 recover from the fatigue. At last, the hole 

 is made. The pupa slips into it, but does not 

 pass through entirely : the head and thorax 

 appear outside; the abdomen remains held in 

 the gallery. 



The glass cell, with its lack of supports at 

 the side, has certainly perplexed my subject, 

 which does not seem to have made use of all 

 its methods. The hole through the sorghum 

 is wide and irregular; it is a clumsy breach 

 and not a gallery. When made through the 

 Mason-bee's walls, it is cylindrical, fairly neat 

 and exactly of the animal's diameter. So I 

 hope that, under natural conditions, the pupa 

 does not give quite so many blows with the 

 pick-axe and prefers to work with the drill. 



Narrowness and evenness in the exit-tunnel 

 are necessary to it. It always remains half 

 caught in it and even pretty securely fixed by 

 the graters on its back. Only the head and 

 thorax emerge into the outer air. This is a 



61 



