INTELLIGENCE OF ANTS. 825 



defending the working community (like soldier termites) against all comers. 

 Whenever I made a hreach in one of their covered ways, all the ants underneath 

 were set in commotion, but the worker-miners remained behind to repair the 

 damage, while the large-heads issued forth in a most menacing manner. 



These two blind species of Eciton are particularly interesting from 

 the fact that in a part of the world so remote from them as Western 

 Africa there is another genus of military ant, also blind, which in all 

 its habits closely resembles the blind Ecitons of Brazil. For, like the 

 latter, Annornia arcens march in long, close columns through tunnels, 

 have no fixed nest, but make temporary halts in shaded places, and 

 are no less organized, remorseless, and irresistible than their American 

 congeners. In one curious particular, however, they differ : the rela- 

 tive position of the marchers and the carriers is reversed, for here the 

 carrier-columns occupy the middle place, w^hile the marching columns 

 with their officers occupy the flanks. When overtaken by a sudden 

 African rain-storm, these ants congregate in a close mass, with the 

 younger ants in the center ; they thus form a floating island. 



It is remarkable that ants of different hemispheres should manifest 

 so close a similarity with respect to all these wonderful habits. The 

 Chasseur ants of Trinidad, and, according to Madame Merian, the 

 ants of Visitation of Cayenne, also display habits of the same kind. 



Special Instances op the Display of High Intelligence. I 

 shall conclude this brief resume of the more important facts at present 

 known concerning the psychology of ants with a few selected observa- 

 tions of the display of high intelligence. It is always difficult to draw 

 the line between instinct and reason, between adjustive action due to 

 hereditary or purposeless habit and adjustive action due to individual 

 and purposive adaptation. But we may be least diffident in accepting 

 as evidence of the latter cases where animals exhibit a power of adapt- 

 ing their actions to meet the requirements of novel circumstances or 

 cirQumstances which can not be supposed to have been of sufficiently 

 frequent occurrence in the life-history of the species to have developed 

 instincts of mechanical response in the individual. It is in view of 

 this consideration that the following instances are selected. 



Ebrard records in his " Etudes de Moeurs " an observation of his 

 own on F. fusca. The ants were engaged in building walls, and when 

 the work was nearly completed there still remained an interspace of 

 twelve or fifteen millimetres to be covered in. For a moment the 

 ants were thrown out, and 



seemed inclined to leave their work, but soon turned instead to a grass-plant 

 growing near, the long, narrow leaves of which ran close together. They chose 

 the nearest, and weighted its distal end with damp earth, until its apex just 

 bent down to the space to be covered. Unfortunately, the bend was too close to 

 the extremity, and it threatened to break. To prevent this misfortune the ants 

 gnawed at the base of the leaf until it bent along its whole length and covered 

 the space required. But, as this did not seem to be quite enough, they heaped 



