THE REACTIONS OF AN ORB-WEAVING SPIDER, 



EPEIRA SCLOPETARIA CLERCK, TO RHYTHMIC 



VIBRATIONS OF ITS WEB. 1 



WILLIAM MORTON BARROWS. 



WITH THREE PLATES. 



I. Introduction 316 



II. Materials and Methods 316 



II. Experiments 3*9 



1. Experiments Using Rhythmic Vibrations 319 



2. Experiments Using a Y-shaped Vibrator 321 



3. Response in the Dark 322 



4. Distribution of Vibrations Through the Web 322 



5. Mutilation Experiments 323 



IV. Discussion and Summary 325 



I. INTRODUCTION. 



The work reported in this paper was suggested by a chance 

 observation 2 made in the summer of 1911. A fly was held close 

 to one of the spiders without eliciting any response; when the 

 fly's vibrating wing was allowed to touch a strand of the web, 

 however, the response was instantaneous and positive. The spider 

 ran to the fly and seized it. A vibrating rubber band held against 

 a strand of the web caused a very similar response. During 

 the summer of 1913 these spiders were studied more carefully in 

 an attempt to determine: first whether the stimulus was vibratory 

 in nature or must be considered to be due to some other force and 

 second whether the response could be identified as a "tropism" 



or taxis. 



II. MATERIALS AND METHODS. 



At the Lake Laboratory maintained by the Ohio State Uni- 

 versity at Cedar Point, Ohio, the large orb weaving spider, 

 Epeira sclopetaria, is very abundant, building its webs on the front 

 porch and in the angles of the building and roof. The habit 



1 Contribution No. 42 from the Department of Zoology and Entomology, Ohio 

 State University. 



2 The note of Boys (80) was not known to the writer until the larger part of 

 these experiments had been carried out. 



