388 'Journal of Comparative Neurology and Psychology. 



to the nest, it would go almost everywhere except to the foot of 

 the incline and roam about until replaced on the stage or incline. 

 If placed on the incline at its foot, it would ascend; but it was not 

 until six minutes to three that the ant, of its own accord, went to 

 the incline and ascended it to the top. Then it returned to the 

 island and meandered. At three o'clock it ascended the incline 

 to the stage. Thus it took it several hours to unlearn the old way 

 and learn the new. 



Although the new adjustment was slowly formed, once formed, 

 it persisted. At a quarter past three the ant was imprisoned. At 

 one minute to seven, when the experiment was resumed, it still 

 retained the new adjustment. At eight o'clock it was imprisoned 

 for the night. At twenty minutes to nine the next morning the 

 experiment was resumed. The ant still retained the new adjust- 

 ment, for in seven minutes it was busy carrying pupae up and 

 down the incline. And all of this seven minutes was not consumed 

 in searching for the nest, for fully half of it was spent by the ant in 

 stretching itself and cleaning its antennae. Contrasting this three 

 minutes with the several hours it took to learn the trick furnishes 

 convincing evidence that ants retain what they acquire. It is 

 unnecessary to describe any more special experiments along this 

 line, for almost every experiment recorded in this paper proves 

 that ants profit by experience. 



In profiting by experience and retaining for a time what it has 

 thus acquired, the ant resembles the fish (Sanford '03), the frog 

 (Yerkes '03), the sparrow (Porter '04), the chick (Thorndike 

 '98, Morgan 'go), the rat (Watson '03), the otter (Hobhouse 

 '01, p. 155-184), the elephant (Hobhouse '01 pp. 164, 165, 169, 

 etc.), and the monkey (Thorndike '98, Hobhouse, '01, pp. 167, 

 182, etc.). It thus appears that the ant is no more guided in its 

 journeys by tropisms, other reflexes, or a homing instinct, than are 

 vertebrates. 



tabulated experimental evidence. 



To give detailed reports of each of the several hundred experiments upon which the above statements 

 are based would require quite a volume. For the benefit of those who desire a more detailed statement 

 than is given above, I close this section with the tabulated results of four series of experiments conducted 

 with Prenolepis imparls Say, two with Formica fusca var. subsericea Sav, and one with Myrmica puncti- 

 ventris Rog. Prenolepis and Formica are fair representatives of the Camponotidae, while Mvrmica is a 

 good representative of the Myrmicidae. The shortest of these series extended over a little more than two 

 days, the longest over a little less than nine days. Some of the series used extended over several times 

 the longest time recorded here; but these serve as typical series. All of the experiments in each series 

 were conducted upoii the same colony; but each series represents a different colony. 



