280 HENRY r. MCCOOK. 



fissure in the beam, which oxteiided for some distance alon;; it, wns, 

 under my observation the main aveniie of coniniunication with the 

 interior. The worker-ants were continually coinin<r out of this crack 

 bearing in their mandibles a fibre of wood. Tliis was dropped upon 

 a cross beam ei<j;hteen inches below, upon which a small heap of the 

 chips mij^ht commonly be seen. [See PI. Til, fij;. 1, b.] At this heap 

 was a squad of workers busily carryin<; the chips to the edfje of the 

 log and dropping them upon the stair which was just beneath. The 

 miller informed me that at first the ants wrought upon this last heap 

 of cuttings also, but finding that he cleared off the litter each day 

 with his broom, finally abandoned this department of their engineer- 

 ing, as quite super-erogatory, and confined their enterprise to the 

 crack and the cross-beam. They thus displayed the very human 

 characteristic of avoiding all needless work. 



This habit of clearing away their cuttings is a settled instinct of 

 these creatures. They have been seen to exhibit it in Fairiuount Park, 

 diligently removing the chips from the foot of a cedar tree in which 

 they dwell. I have often observed the same habit in certain colonies 

 •which inhabit the trees in the neighborhood of the Academy of Natural 

 Sciences on Logan Square, Philadelphia. A small maple tree, eight 

 inches in diameter, on Race street near Eighteenth, was the special 

 object of attention. One squad wrought on the north side, in a cavity 

 ei-'ht or nine inches long by three or four wide, a little over one foot 

 above the sidewalk. Within the cavity quantities of chips were 

 accumulated. At this point also workers were continually arriving 

 bearing iood, such as small worms, and brownish, grain-like objects 

 which I took to be coccidoe, although I cannot speak with certainty. 

 1 traced one of these workers from the cavity some distance away to 

 the next tree up whfch it ascended until lost to sight. It was per- 

 haps on a foraging expedition among the upper branches. In order 

 to determine if the wood-workers would care for the f )od also, 1 took 

 a cocceus from a carrier and laid it in the cavity. One of the cutters 

 having dropped her bit of wood, seized this and carried it within. 

 There is probably n(» permanent division of labor, but all the workers 

 either carve at the galleries or forage for supplies as occasion or 

 inclination may suggest. 



On the west side of the tree, a few inches from the roots, there was 

 a small tubular opening, which was hidden behind a bulging scale 

 of bark. Out of this the ants were dropping cuttings which had 

 accumulated in a goodly heap at the base of the trunk. Two workers 

 ■were engaged upon this heap carrying the litter to the curbstone and 



