44 ARRANGEMENT OF CHAMBERS. 



represents garden mould, which the ants have them- 

 selves excavated, as shown in the figure. For the 

 small doorway (a), indeed, I am myself responsible. 

 I generally made the doorways of my nests narrow, so 

 as to check evaporation and keep the nests from 

 becoming too dry. It will be observed, however, that 

 behind the hall (6) the entrance contracts, and is still 

 further protected by a pillar of earth, which leaves on 

 either side a narrow passage which a single ant could 

 easily guard, or which might be quickly blocked up. 

 Behind this is an irregular vestibule (c), contracted 

 again behind into a narrow passage, which is followed 

 by another, this latter opening into the main chamber 

 (d). In this chamber several pillars of earth are left, 

 almost as if to support the roof. Behind the main 

 chamber is an inner sanctum divided into three cham- 

 bers, and to which access is obtained through narrow 

 entrances (/, /, /, /). Most of the pillars in the main 

 chamber are irregular in outline, but two of them 

 (<7, <j) were regular ovals, and round each, for a distance 

 about as long as the body of an ant, the glass had been 

 most carefully cleaned. This was so marked, and the 

 edge of the cleaned portion was so distinct, that it is 

 impossible not to suppose that the ants must have 

 had some object in this proceeding, though I am unable 

 to suggest any explanation of it. 



I have already mentioned (ante, p. 23), that there 

 is evidence of some division of labour among ants. 

 Where, indeed, there are different kinds of workers, 



