NATURE'S CRAFTSMEN 



may imagine the enormous work involved in carrying 

 the formicary to such a depth, or even much less, be- 

 neath the space covered by a circle ten or twelve feet 

 in diameter. 



The strain of such use upon the ants' working-tools — 

 the mandibles — must be great. How does it affect 

 them? An interesting fact developed from examina- 

 tions of the mandibles of many specimens. The normal 

 jaw has well-defined teeth, sharp and hard. The jaws 

 of wofkers showed all stages of abrasion, from a point- 

 less long tooth to absolute toothlessnecs. 



This is seen elsewhere in the insect world. The teeth 

 and dentations on the outer side of the tibia of fossorial 



EXAMPLES OP ABRADED DENTITION OF THE MANDIBLES OF AGRI- 

 CULTURAL ANTS 



The first figure shows the perfect mandible 



beetles are frequently worn to the extent of their entire 

 disappearance; and the same is true of the mandibular 

 teeth. The surface sculpture will in like manner dis- 

 appear, the striations upon the back so wearing away 

 by rubbing against stones and logs that they are readily 

 known as second-season species. One wonders what 

 becomes of these toothless ants, since their efficiency as 

 masons must be impaired, and in a measure as har- 



94 



