Turner, Homing of Ants. 399 



conveying pupae to the nest. In a short time after the first few 

 trips had been made across the band, the ant would be making its 

 journeys to and from the nest as rapidly and regularly as down the 

 old incline. Then a new special incline or a plain incline of the 

 ordinary kind was substituted for the one just used and that one 

 transferred to the control stage. In each case the animal used 

 for control was much disturbed, which demonstrated that, from 

 the ant's standpoint, the transverse band of volatile substance was 

 still on the incline. Evidently that odor or better that volatile 

 substance had become for ant number one a familiar element of 

 the homeward path. This experiment then shows that the vola- 

 tile chemical peculiarities of the path form a portion of the impres- 

 sion experienced by ants on their journeys (Figs. 9, 18). 



Experiments with Tactile Stimuli. — That tremors affect the 

 home-going of ants is evidenced by the fact that a comparatively 

 slight tap on the stage will cause an ant to halt and a severe jar 

 will so disturb it as often to make it necessary for the ants to re- 

 learn the way home (Fig. 12, D). 



A number of experiments were performed for the purpose of 

 discovering whether ants are affected by the surface character of • 

 the pathway. In this case a worker was trained to go down and 

 up a smooth black incline. After it had reached the condition 

 where it was not disturbed by the substitution of another smooth 

 black incline for the old one, a black incline with a velvety sur- 

 face was substituted for the smooth black one. Myrmica punc- 

 tiventris Rog. was much disturbed by the change (Fig. 10, g), but 

 Formica fusca was not (Fig. 18, M; 14, P). 



It seems legitimate to assume that tremors and jars probably 

 give kinesthetic stimuli and that the velvety surface gives a tactile 

 stimulus. Such being the case, kinesthetic impressions probably 

 form part of the mental furniture of all ants examined by me and 

 at least some ants have tactile impressions. 



Experiments with Optic Stimuli. — To see if optical impressions 

 are received by ants two kinds of tests were conducted : experiments 

 with ants working in concert, and with marked individuals. 



In experiments of the first type a cardboard stage from which a 

 cardboard incline led to the island was used. A 16 c.p. incan- 

 descent electric lamp was placed, sometimes near the side to 

 which the inclined plane was attached, and sometimes near the 

 opposite side. After the ants had thoroughly learned the way 



