No. 2.] MENTAL POWERS OF SPIDERS. 401 



ing-spiders (Attidae) only perceive their prey when two or 

 three inches distant.^ 



When our spiders came within a fifth of an inch of their 

 cocoons, and yet gave no sign of seeing them, we were almost 

 ready to agree with Professor Forel ; but a little further consid- 

 eration convinced us that we were judging them too hastily. 



Let us go over the history of the egg-sack. In forming it, 

 the spider first makes the upper part, and then, holding the 

 openings of the oviduct against it, forces out the eggs. After 

 the eggs are laid she uses the spinnerets, and possibly the pos- 

 terior legs, to complete the cocoon. When it is finished she 

 bends down the end of the abdomen, and attaches it there by 

 Hnes of web. All this time she has probably not seen it once ; 

 and she never will see it, since it remains on the under side of 

 the body until the young spiders come out, when they attach 

 themselves to her back. 



Now, bearing in mind that a perception is the interpretation 

 of a sensation in terms of past experience, what is there in the 

 experience of this spider to enable it to make a mental synthe- 

 sis of the sensation of sight, with those other qualities of the 

 cocoon which are learned by touch? The spider doubtless saw 

 the cocoon, but could only recognize it as such through the 

 medium of the sense of touch. 



That this explanation is the correct one is made more prob- 

 able by the fact that those spiders that not only touch their 

 cocoons, but also see them, evidently depend on sight in recog- 

 nizing them, if they are removed. 



We took the cocoon from Theridion blandtim Hentz, and 

 placed the spider in a bottle three inches high. After she had 

 settled herself in the upper end, we dropped the cocoon into the 

 bottom of the bottle. She immediately descended, picked it 

 up, and returned to her former position. We repeated this ex- 

 periment several times. 



Theridion frondeiini Hentz was placed under an rnverted 

 tumbler, four inches high. While she was standing on the upper 

 surface of the glass the edge was lifted and the cocoon pushed 

 under. She at once lowered herself, seized it, and took it up to 



^Sensations Jes Insect es, I. Recueil Zcologique Suisse, Tome IV., No. i, pp. 

 18, 19- 



