324 WILLIAM MORTON BARROWS. 



this spider was in its web. During the night the web had been 

 repaired and a new spiral thread put on. 



In recording the test made on this spider and those following, 

 IX o'clock, XII o'clock, etc., refers to the position at the edge of 

 the web which corresponds to the same hour on the clock face. 

 Thus VI o'clock is used to designate the edge of the web which 

 the spider normally faces when at rest, i. e., directly downward. 



Experiment i. Spider with both forefeet cut off. Fork giving 

 100 vibrations per second touching web in 

 III o'clock position spider reached fork 8 inches from center in 



3 seconds. 



IX o'clock position reached fork (8 in.) in 2^2 sec. 

 VII o'clock position reached fork (8 in.) in 2^4 sec. 



Experiment 2. Spider with third legs cut beween femur and 

 patella. 



IX o'clock position reacted 8 in. in 2% sec. 

 Ill o'clock position reacted 8 in. in 2> sec. 

 XII o'clock position reacted 8 in. in 7^4 sec. 



This individual showed some difficulty in climbing, but 

 oriented accurately. 



Experiment 3. Spider with second legs cut off at patella. 

 Ill o'clock position reacted 7 in. in i^ sec. 

 XII o'clock position reacted 7 in. in i^ sec. 



X o'clock position reacted 7 in. in i> sec. 



Experiment 4. Spider with fourth legs cut off at patella. 

 Reactions entirely normal as given above. 



Another set of experiments which need not be detailed were 

 carried out. In these the right first leg and left fourth leg were 

 cut off and other similar combinations were made. In all cases 

 orientations and the locomotion following were entirely normal 

 except for the slight difficulties in locomotion which might be 

 expected. These experiments indicate that the sense organs used 

 in reacting to the vibratory stimuli are not restricted to any one 

 pair of legs below the metatarsus. There are two possible dis- 

 tributions of sense hairs which would seem to make possible the 

 reactions detailed above ; the sense organs may be confined to the 

 feet, where they come in contact with the web or they may be 

 located on the le.gs or body in such a manner that they pick up 



