302 AMERICAN SPIDERS AND THEIR SPINNINGWOKK. 



• 



upon silken nets, are chiefly dependent ujion siji'ht for knowledge of their 

 victim's i^resence and power to secure it. 



A few experiments were made to determine where the organ of hearing 

 is located, which, as far as they go, seem to confirm my own opinion as 

 expressed above, that the auditory apparatus is but little specialized, and 

 is distributed over a considerable portion of the epidermis. The removal 

 of the palps appeared to make no difference in the power of individuals to 

 respond to the vibrations of the fork. So also the removal of the first 

 pair of legs seemed to leave the auditory organs intact, at least made no 

 impairment of power to respond to sound. 



I will now describe two of my own experiments, as illustrative of the 

 method inirsucd and tlie grounds for reaching my conclusion. An adult 

 female Domicile spider, hanging in the centre of her orb, was 

 uning tested by an "A" tuning fork. The fork in rapid vibration was 

 pgj.^jjjgjj^g moved all around her, gradually approaching until the instru- 

 ment was within a few millimetres of her person. All parts of 

 the body were thus tested and no signs of excitement appeared. The fork 

 was then touched to the top of the web, when Domicile immediately 

 showed signs of excitement, acting precisely as if an insect were entangled 

 at that point. She turned herself in the direction of the fork, grasped 

 the radii leading outward to the point of contact, pulled upon them in the 

 usual way as' though testing the strength or entanglement of the supposed 

 insect, and then gradually approached the point of agitation. I withdrew 

 the fork, and, as the spider came up to the margin of the web where the 

 instrument had been, she turned around, made several motions as thoygh 

 examining the strands, spun out a few lines, and went back to her hub, 

 dragging a thread after her. 



The fork was then placed at the bottom of the web, then at the sides, 

 and so successively to various points on the circumference of the orb. 

 The same action substantially resulted, the spider always going to the spot 

 where the fork was vibrating against the lines of her web. Finally, I suf- 

 fered the fork to remain as the spider approached. She touched it with 



her fore feet; at once showed tokens of surprise, indeed of some 

 A Dis- 



, stronger emotion ; she seemed to be expressing the feeling, " I 



Spider. have been fooled ; " turned her back upon the fork, shot out a 

 thread from her spinnerets, and scampered away to the hub, 

 where she curled herself up, drawing her legs toward her face until the 

 knees projected above the head, exliibiting what I cannot express by 

 another phrase than tokens of disgust. 



I then laid the vibrating fork upon the outer lines, but Domicile would 

 not respond. I revolved the fork around the hub, close to her, as at the 

 beginning of the experiment. This time, instead of remaining motion- 

 less, she waved her fore feet back and forward, as though she had observed 

 the vibration and were feeling the situation. After a few moments' 



