392 PECKHAM. [Vol. r. 



more than to both hear and see it. The presence of the fork, 

 when not in vibration, brought no response, nor did rapidly- 

 moving it to and fro in front of her attract her attention. 



August 13. — The large fork, in vibration, was held near a 

 female of A. riparia. She at once gave the usual sign that she 

 heard it. It was next held behind her, and entirely out of her 

 sight, when she quickly turned in the direction of the sound. 



August 14. — Tried a new species, a young PJiillyra inammeata 

 Hentz. When the vibrating C fork approached she lifted first 

 one, and then the other, of the anterior legs. 



Were it necessary, we could cite a great many similar experi- 

 ments which had like results, to show that certain spiders indi- 

 cate that they hear a vibrating tuning-fork by characteristic 

 movements of the legs. Another set of spiders, however, man- 

 ifested their perception of the sound in a different way. With 

 these the approach of a vibrating fork seemed to cause greater 

 alarm, making them drop from the web and keep out of sight 

 for a longer or shorter time. However, after one of these 

 spiders had been subjected to the experiment several times, it 

 would, instead of dropping, raise its legs in the manner described 

 above. 



For example, when the vibrating C fork approached a female 

 of E. labyrintJiea as she stood in her web, she fell. This was 

 repeated eleven times, the spider falling each time, but at the 

 twelfth she merely raised her first legs. 



A few days after this experiment we found a more excitable 

 spider of the same species. Not until she had fallen out of the 

 web twenty-two times, at the approach of the fork, could she 

 restrain the impulse to drop. It was apparent, however, after 

 the seventh or eighth time, that she was less startled by the 

 sound than at first, since the distance that she fell and the 

 period of time that elapsed before she returned to the web grew 

 shorter and shorter in the later experiments. At first she fell 

 fifteen or eighteen inches, and remained at' the end of her line 

 for several minutes, while toward the last she fell only an inch or 

 two, and immediately ran back to the web. After the twenty- 

 second trial she only held up her legs as the fork approached. 

 Finally, completely worn out and disgusted, she retreated to a 

 neighboring branch, drew in her legs, and remained sullenly 

 unresponsive to all further attempts. 



