THE SENSES AND THEIR ORGANS. 



285 



Professor Wilder, when studying the habits of Nephila pluniipcs,i came 

 to the condusion that spiders of that species cannot see anything at all, 

 whether near or remote. I do not accept the conclusion, but 

 ^^^.\^ give some facts on which it was based. The sjiiders paid no at- 

 tention to an object put close to them, nor to the quiet movements 

 of any one about them. An individual would often rush by an insect en- 

 tangled in her net, if it chanced to cease its struggles before she had accu- 

 rately determined its position; she would then slowly return to the centre 

 of the web, and wait until another vibration indicated the whereabouts 

 of the insect. A t\y offered upon the point of a needle would not be no- 

 ticed until it began to buzz, when it would be' seized at once. Nephila, 

 however, always prefers the light, and constructs her large orbs where the 

 sun can reach them. The J'oung mani- 

 fest the same instinct, and in confine- 

 ment seek the sunny side of a glass 

 vessel. 



In order to test the ability of the 

 Furrow spider to work upon her web 

 without the aid of daylight. 

 Orbs J secluded one within a large 



tVi n k ^^^^ with a sliding glass door. 

 She soon spun an orlnvel) 

 across the cell as close to the glass door 

 and as far toward the light as could well 

 be. Fortunatelj' not a line of the snare 

 was attached to the glass itself, so that 

 I could draw it back and forth at will. 

 I next cut away the lower foundation 

 line, broke up the entire lower part of 

 the web, and the box was then completely darkened. Next day, when 

 the covers and screens were removed, the web was found thor.oughly 

 mended, every part being so neatly and accurately repaired that it was 

 scarcely possible to determine Mdiich was the patchwork and whicli the 

 original snare. Even if we admit that some particle of light may have 

 entered the cell, the sense of touch in this case must have been the chief 

 reliance. 



In other experiments the spider's sight, in so far as that sense can be 

 apprehended by human experience, could have had no part in 

 Cocoon- directing her work. I liave repeatedly confined female Orbweav- 

 fh^n ir *'^'^' ^P^""^ strix, sclopetaria, insularis, domiciliorum, and triara- 

 nea, Acrosoma rugosa, and others, in paper boxes absolutely im- 

 pervious to light, and opening them the next day have found eggs deposited 



Fig. 283. Sagittal section tlirougli an anterior 

 median eye, eight days after hatching; the 

 retinal portion has not yet reached its full 

 development. X about 350. Ins, lens ; vit, 

 " vitreous body ;" eta, cuticula ; hd, hypoder- 

 niis; rtn', first (inverted) layer of optic invag- 

 ination ; rtu", second tnon inverted) layer. 

 (After Locy.) 



1 Proceed. Boston Soc. Nat. Hist., Vol. X., page 208. 



