THE SENSES AND THEIR ORGANS. 



Professor Wilder, when studying the habits of Nephila plnmipes, 1 came 

 to the conclusion 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 spiders 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 fly 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 young 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 



Made in ,, ... ,. ,. , -, 



th D k a snt ' m g glass door. 



She soon spun an orbweb 

 across the cell as close to the glass door 







.eta 



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- 

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

 ination ; rtn", second (non inverted) layer. 

 (After Locy.) 



rtn 



and as far toward the light as Could Well Flo . 283. Sagittal section through an anterior 



be. Fortunately 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 thoroughly 



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



scarcely possible to determine which was the patch work and which 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 have repeatedly confined female Orbweav- 

 th T~> lc ers ' Epeira 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 



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



