434 WILLIAM M. MANN 



through imitation. Coinetz does not believe that the social 

 cooperation of ants is altogether a result of individual action, 

 but points out that there may be much less mutualism than is 

 generally believed. 



Cornetz (8) believes from a study of Myrmecocystus that this 

 ant has, to a greater or less extent, an impression of the terri- 

 tory immediately surrounding the nest entrance, but that this 

 memory is inconstant and of short duration, especially when 

 based upon the visual sense. When the memory is olfactive it 

 may persist for a long time. 



Cornetz (10) compares the sense of direction of the rat and 

 the ant. The rat observed by Szymanski (Essais pour exprimer 

 par des nombres le rapport entre des stimulants de genies dif- 

 ferents. Archiv. f. d. ges. Physicl., Bonn, rgr2) when liberated 

 in a box containing a pan of water wandered about until it 

 found this, but each succeeding time, by the "dropping of use- 

 less movements," shortened the distance traveled, till it finally 

 went directly to the water. On each trip the rat had revived 

 impressions that had been received on the previous trips. The 

 ant, on the other hand, is guided by an impression received on 

 each outgoing journey, and revived on the homegoing route. 

 To what extent the ant is able to remember a direction "to 

 the right" or "to the left" is still completely unknown, but 

 Cornetz ventures the hypothesis that the ant does not need a 

 memory, but possesses "en soi" a sense of direction. This he 

 believes to be not at all impossible, though hard to conceive. 



Cornetz (roa) experimented on the estimation of distance in 

 ants. Workers of Pheidole pallidula away from the nest were 

 decoyed by little pieces of cheese on to a knife blade, and taken 

 to a point at a short distance away. When the ant dismounted 

 from the blade it set out in a line parallel and opposite to the 

 outgoing trail, reversing the direction of march in the manner 

 usual to ants, but owing to the change of the starting point, 

 not in the direction of the nest. Cornetz made careful comparison 

 of the distance traveled on the wrong trail, and the distance to 

 the nest if the ant had not been moved to another starting point. 

 Where both trails were on the same kind of material, there was 

 an error of from one-tenth to one-fifth of the distance, though 

 one ant erred by three-fifths, which is an abnormal amount. 

 When the trails were different (one on cement and the other on 



