The Mason-bees 



tools and instinctive faculties for accomplish- 

 ing the final act of its metamorphosis, namely, 

 the act of emerging from the cocoon and from 

 the cell. Its mandibles provide it with scis- 

 sors, file, pickaxe and lever wherewith to cut, 

 gnaw through and demolish either its cocoon 

 and its mortar enclosure or any other not too 

 obstinate barrier substituted for the natural 

 covering of the nest. Moreover — and this is 

 an important proviso, but for which the outfit 

 would be useless — it has, I will not say the will 

 to use those tools, but a secret stimulus invi- 

 ting it to employ them. When the hour for 

 the emergence arrives, this stimulus is aroused 

 and the insect sets to work to bore a passage. 

 It little cares in this case whether the material 

 to be pierced be the natural mortar, sorghum- 

 pith, or paper; the lid that holds it imprisoned 

 does not resist for long. Nor even does it 

 care if the obstacle be increased in thickness 

 and a paper wall be added outside the wall of 

 clay: the two barriers, with no interval be- 

 tween them, form but one to the Bee, who 

 passes through them because the act of get- 

 ting out is still one act and one only. With 

 the paper cone, whose wall is a little way off, 

 the conditions are changed, though the total 

 38 



