1901.] 



NATURAL SCIENCES OF PHILADELPHIA. 



529 



irom five to teu millimeters wide. The action of ihe ant when 

 the scent is obscured proves that her trail is individual, and that 

 it is under foot. She does not more readily pass the point of 

 obscuration on account of it having been previously traversed by 

 her comrades. Her action is the same whether she be the first to 

 arrive at the newly-laid flooring or whether many ants have ci'ossed 

 it before her. 



The power of perceiving the individual trail lies in the tenth 

 segments of the antennse. When 

 deprived of this segment the ant 

 is no longer able to find her way 

 in wilh the pupse, but wanders 

 about helpless and bewildered. 

 Ants deprived of nearly all of 

 the eleventh and all of the 

 twelfth segments continued to 

 carry the pup^ through the runs 

 of the maze, though with dimin- 

 ished physical vigor. The ant 

 could pick up her scent so long 

 as a tenth segment was intact, 

 and no louger. For experiments 

 in following the trail, I selected 

 ants that had been previously 

 distinguished by diligence in the 

 carrying in of pupre and later on 

 set them to work with clipped 

 antennse.' 



That memory 2)^oys ci part i)i 

 the journeys as well as in other 

 proceedings of ihe ant, is shown 

 by experiments made by me in 

 gradually increasing the width of 



' For removing the whole or any part of the antennse of the ants used in 

 the experiments described in this paper, tlie antennse were clipped with 

 sharp scissors, Ihe wound was merged for five seconds in eighty percent, 

 alcohol to coagulate the blood ; the aut was isolated upon a wet sponge in a 

 Petri cell, without food, for a day. and was thereafter daily placed upon some 

 acceptable food, such as moistened sponge cake, soft pie crust, or bread 

 touched with honey. No insect food was given, and the cell was kept very 

 clean. After fifteen days or longer about forty per cent, of the ants recov- 



34 



Left Antenna of Stenamma 

 fulvum piceum. 



