ANTS AND SOME OTHER INSECTS. 43 



proach or recede from them, and perceiving the surfaces both simul- 

 taneously and successively as parts of objects differing in odor and 

 position. It is clear from the very outset that such sense-organs 

 would enable you to construct a veritable odor-chart of the path 

 you had traversed and one of double significance : 



1. A clear contact-odor chart, restricted, to be sure, to the 

 immediate environment and giving the accurate odor-form of the 

 objects touched (round odors, rectangular odors, elongate odors, 

 etc.) and further hard and soft odors in combination with the tac- 

 tile sensations. 



2. A less definite chart which, however, has orienting value 

 for a certain distance, and produces emanations which we may pic- 

 ture to ourselves like the red gas of bromine which we can actually 

 see. 



If we have demonstrated that ants perceive chemical qualities 

 through their antennae both from contact and from a distance, then 

 the antennas must give them knowledge of space, if the above for- 

 mulated law is true, and concerning this there can be little doubt. 

 This must be true even from the fact that the two antennae simul- 

 taneously perceive different and differently odoriferous portions of 

 space. 1 



They must therefore also transmit perceptions and topograph- 

 ically associated memories concerning a path thus touched and 

 smelled. Both the trail of the ants themselves and the surround- 

 ing objects must leave in their brains a chemical (odor-) space- 

 form with different, more or less definitely circumscribed qualities, 

 i. e., an odor-image of immediate space, and this must render as- 

 sociated memories possible. Thus an ant must perceive the forms 

 of its trail by means of smell. This is impossible, at least for the 

 majority of the species, by means of the eyes. If this is true, an 

 ant will always be able, no matter where she may be placed on her 



1 It is not without interest to compare these facts with Condillac's discussion 

 ( Treatise on the Sensations} concerning his hypothetical statue. Condillac shows 

 that our sense of smell is of itself incapable of giving us space knowledge. But it 

 is different in the case of the topochemical sense of smell in combination with the 

 antennary movements. Here Condillac's conditions of the gustatory sense are ful- 

 filled. 



