INTELLIGENCE OF ANTS. 499 



memory by repetition, and the impression is liable to become effaced 

 by lapse of time. Sir John Lubbock found it necessary to teach the 

 insects, by a repetition of several lessons, their way to treasure, if that 

 way were long or unusual. With regard to the duration of memory 

 in ants, it does not appear that any direct experiments have been 

 made ; but the following observation by Mr. Belt on its apparent du- 

 ration in the leaf-cutting ant may be here stated : In June, 1859, he 

 found his garden invaded by these ants, and on following up their 

 paths he found their nest about a hundred yards distant. He poured 

 down their burrows a pint of diluted carbolic acid. The marauding 

 parties were at once drawn off from the garden to meet the danger at 

 home, while in the burrows themselves the greatest confusion pre- 

 vailed. Next day he found the ants busily engaged in bringing up 

 the ant-food from the old burrows and carrying it to newly formed 

 ones a few yards distant. These, however, turned out to be intended 

 only as temporary repositories ; for in a few days both old and new 

 burrows were entirely deserted, so that he supposed all the ants to 

 have died. Subsequently, however, he found that they had migrated 

 to a new site, about two hundred yards from the old one, and there 

 established themselves in a new nest. Twelve months later the ants 

 again invaded his garden, and again he treated them to a strong dose 

 of carbolic acid. The ants, as on the previous occasion, were at once 

 withdrawn from his garden, and two days afterward he found " all 

 the survivors at work on one track that led directly to the old nest of 

 the year before, where they were busily employed in making new 

 excavations. ... It was a wholesale and entire migration." Mr. Belt 

 adds, " I do not doubt that some of the leading minds in this formi- 

 carium recollected the nest of the year before, and directed the migra- 

 tion to it." Of course, it is possible that the leaders of the migration 

 may have simply stumbled on the old burrows by accident, and, find- 

 ing them already prepared as a nest, forthwith proceeded to transfer 

 the food and larvae ; but, as the old and the new burrows were sepa- 

 rated from one another by so considerable a distance, this supposition 

 does not seem probable, and the only other one open is that the ants 

 remembered their former home for a period of twelve months. This 

 supposition is rendered the more probable from a somewhat analogous 

 case recorded by Karl Vogt in his " Lectures on Useful and Harmless 

 Aiiimals." For several successive years ants from a certain nest 

 used to go through certain inhabited streets to a chemist's shop six 

 hundred metres distant, in order to obtain access Xo a vessel filled 

 with sirup. As it can not be supposed that this vessel was found in 

 successive working seasons by as many successive accidents, it can 

 only be concluded that the ants remembered the sirup-store from 

 season to season. 



Recogxitiox. I shall now pass on to consider a class of highly 

 remarkable facts. It has been known since the observations of Huber 



