398 "Journal of Comparative Neurology and Psychology 



I have already stated, this no more proves that normal ants do not 

 utilize odors in their home-going than does the fact that blind men 

 are able to find their way about demonstrate that normal men do 

 not use visual sensations in their journeys. 



Most writers lay great stress upon the odor of the trail, and 

 FiELDE claims that a special organ (the ninth joint of the flagel- 

 lum) exists for the detection of the track-odor. If I interpret my 

 experiments aright, it is not the scent of the trail merely, but the 

 odor-peculiarities of the pathway as such, that form a part of the 

 impression which enables ants to pass home. The readiness with 

 which ants react to any strange odor that is added to their pathway 

 lends support to the view" that the odors of the pathway itself form 

 a part of the psychic impression of home-going ants. Pieron 

 himself says that ants traveling in a common road are arrested by 

 unexpected odors; they flee from odors of their enemies and cross 

 with little difficulty scents of vegetable origin. To my mind, this 

 statement of Pieron's supports the view just presented. 



To test this matter in the laboratory, several experiments like 

 the following were tried. A colony of Formica fusca var. subser- 

 icea Say was divided and each nest placed in the same relative 

 position on diff^erent Lubbock islands. On each island was 

 placed a cardboard stage from which an incline led to the island. 

 Each of these inclines led from the same relative position on the 

 stage and in the same direction. On each stage was placed a 

 large number of pupze and a marked worker. After each worker 

 had thoroughly learned the way to and from the stage to the 

 nest, the experiment proper was performed. The ant that was 

 carrying pupae from stage number one was the subject of the 

 experiment proper. The ant on stage number two being used, 

 in the manner hereafter mentioned, as a control. 



Special inclines were made by placing across the middle of the 

 white slip used for ordinary inclines a transverse band, three-fourths 

 of an inch wide, of some odoriferous substance. The chemicals 

 used for this purpose were xylol, oil of cedar and oil of cloves. 

 When the ant on stage number one had become so well acquainted 

 with the way home as not to be disturbed by the substitution of a 

 new incline of the same kind for the old, the old incline was replaced 

 by one of these special inclines. In each case the ant was very 

 much disturbed, but in the case of both the xylol and cedar oil, 

 after a while, the ant began to go back and forth across the band 



