BUCKINGHAM. 



DIVISION OF LABOR AMONG ANTS. 



447 



were confined in the Fielde nests already mentioned (Figure G). In 

 all cases the chambers were connected with each other by two passages, 

 one at each end of the partition. In each of the chambers was a moist 

 sponge, and both chambers were kept moderately dark by pasteboard 

 covers laid over the glass. The ants were placed in chamber A, the 

 food in chamber B. One of the passages between ^4 and B was blocked 

 by a plug of cotton, while in the other was placed a trap-door which 

 allowed the ants to pass from A to B, but not in the reverse direction. 

 The trap-door (Figures 7-1 1) was made as follows : A piece of mica, a, 

 slightly narrower than the passage, rested on a fulcrum, 0, in such a 

 way that one end touched the floor of the nest in chamber .1, while the 

 other came against the roof (c) of the passage in chamber B. The roof, 

 c, covered the whole passage between A and B. In Figure 8, a front 



Figure 6. 



elevation, are shown, besides the parts already mentioned, d, the out- 

 side wall of the nest in cross section, and e, the cross partition between 

 A and B, also in section. The fulcrum (b) consisted of a short piece 

 of straightened watch spring just long enough to fit easily across the 

 passage, and supported, edge up, between two strips of thin card-board, 

 cut as shown in Figure 9, where b is the steel watch spring, and k one 

 of the supporting cards. The dotted lines (g) show where the card was 

 bent at right angles to form the parallel wings, /, which were glued to 

 the glass wall of the passage (Figure 8, d and e). The portions ^ of the 

 card-board remained in a plane parallel to b and hence perpendicular 

 to./'. Both edges of the mica plate (a) were notched at the middle 

 (Figure 11) to receive the projecting edges, i, of the vertical card-board. 

 This arrangement prevented the slipping of the mica plate on the ful- 

 crum, while allowing freedom of motion in a vertical direction. The 

 two arms of the mica plate were of unequal length, the longer and 



