NO. 9 OLFACTORY SENSE OF INSECTS MclNDOO I9 



species that had its antennae cut off. The male at once vibrated its 

 wings and started toward the rod. 



Fielde (1901a), who has made a special study of ants, claims in her 

 various papers that ants have a keen sense of smell. The same author 

 (1901b) asserts that. 



The power of perceiving the individual track lies in the tenth segment of the 

 antennae. When deprived of this segment the ant is no longer able to find her 

 way in with the pupae, but wanders about helpless and bewildered. Ants 

 deprived of nearly all of the eleventh and twelfth segments continued to carry 

 the pupae through the runs of the maze, tliough with diminished pliysical vigor. 

 The ant could pick up her scent so long as a tenth segment was intact, and no 

 longer. 



Miss Fielde clipped the antennse with sharp scissors and 15 days 

 after the operation about 40 per cent of the ants recovered from the 

 effect of the shock. 



Before their recovery the ants were listless and abnormally irritable ; and 

 they attacked with self-destructive violence any moving thing that touched 

 them. One antennae performs all the functions of a pair. * * * Every 

 Stenamma fulvum piceum has an odor manifest in all parts of her animate 

 body, and discerned by herself and by other ants through the eleventh seg- 

 ment of the antennae. 



The commingled odors of all the ants in the nest constitute what she 

 calls the " aura " of the nest. 



It is diffused in air or ether from the animate occupants of the nest, and it 

 is discerned by the ant through the twelfth, the distal, segment of the 

 antennae. 



When deprived of the distal segment the ants were not alarmed 

 when introduced into the nest of aliens ; they did not flee, nor did 

 they endeavor to hide ; thus their behavior is strikingly different from 

 that of unmutilated ants. Also she found (1907) that queens de- 

 prived of their antennae did not behave normally. 



So long as the eighth and ninth segments of the antennae are uninjured, the 

 ant may continue to lift and care for the eggs, larvae, or pupae, but after the 

 removal of these segments she loses all interest in the young and performs 

 no further work in the nursery. * * * Marked ants of two hostile colonies, 

 when clipped across the tenth segments, associated freely and amicably with 

 one another during several days in the care of the pupae belonging to one of 

 the two colonies. 



A paper by the same author ( 1903a) summarizes the foregoing and 

 adds observations on some of the segments not heretofore mentioned. 

 The following perceive these particular odors : The eleventh or distal 

 segment, the nest odor ; the tenth, the colony odor ; the ninth, the 

 individual track ; the eighth and seventh, the inert young ; the sixth 



