412 PROCEEDINGS OF THE ACADEMY OF [May, 



forks, while those that make no webs gave not the slightest heed to 

 sounds. They attempted to explain this phenomenon by the dif- 

 ference in the method of capturing food, but now it is pretty generally 

 agreed that in all such experiments the vibrations from the tuning- 

 forks agitate the webs. 



McCook cites several recorded cases where spiders are supposed to 

 hear and in a few cases to really enjoy music, but he thought that such 

 responses of the araneads could be explained in other ways than by 

 imagining that they have an auditory perception. McCook con- 

 cluded after many experiments with musical instruments, various 

 sounds of the human voice and sonorous objects that if spiders have 

 any sense of hearing, that sense is distributed, like the sense of smell, 

 over the entire body and that it can scarcely be distinguished from the 

 sense of touch. 



Dahl (1883) called certain peculiar hairs on the three end joints of 

 the legs auditory hairs. They are even so constant in arrangement 

 that he attaches an important taxonomic significance to them. In 

 order to prove the possibility that they have an auditory function he 

 placed the foot of a dead dried spider under the microscope. Then 

 he struck a deep tone on a violin and noticed a vibration of these hairs. 

 From this evidence he claimed that spiders have an auditory sense, 

 although with live araneads he could not always notice any reaction 

 to tones. He stated that a nerve fibre runs out from the base of each 

 of these hairs but presents no drawing of such. The next year Dahl 

 described and presented a drawing of the nerve of a spider's leg which 

 can be easily recognized by its long irregularly arranged nuclei. He 

 said that from this nerve fibres run out to the individual auditory 

 hairs, but even here he produces no drawing of such a connection. 

 Judging from the similarity in structure of various kinds of hairs 

 Wagner (1888) asserted that Dahl's so-called auditory hair could not 

 have such a function. 



Westring (1843) was the first to mention a stridulating organ in a 

 theridiid, Asagena phalerata. Wood-Mason (1875) exhibited specimens 

 of a gigantic theraphosid which he called Mygale stridulans. These 

 produced loud stridulating sounds. Campbell (1881) observed these 

 organs in three or four different species of theridiids. Peal (1895) 

 noticed the stridulating phenomena of an Australian spider. Pocock 

 (1895) discovered and gave drawings of a stridulating organ in the 

 male of Cambridgea antipodtana, an agalenid. Since the organs were 

 present only in the males he concluded that the sound emitted must 

 be a sexual call. Spencer (1895) observed a theraphosid which was 



