320 



INSECT ARCHITECTURE. 



indeed, mnst often happen, did they not take careful 

 precautions to avoid it ; for we have observed that they 

 seldom, if ever, leave a thread to float at random, except 

 when they wish to form a bridge. AVhen a spider drops 

 along a line, for instance, in order to ascertain the strength 

 of her web, or the nature of the place below her, she in- 



Triple-clawed toot of a Spider, magnified. 



variably, when she reascends, coils it up into a little ball, 

 and throws it away. Her claws are admirably adapted for 

 this purpose, as well as for walking along the lines, as may 

 be readily seen b}^ a magnifying glass. 



There are three claws, one of which acts as a thumb, 

 the othei"s being toothed like a comb, for gliding along the 

 lines. This structure, however, unfits it to walk, as flies 

 can do, upon any upright polished surface like glass ; 

 although the contrary* is erroneously asserted by the Abbe 

 de la Pluche. Before she can do so, she is obliged to 

 construct a ladder of ropes, as Mr. Blackwell remarks, f by 

 elevating her spinneret as high as she can, and laying 

 down a step upon which she stands to form a second ; and 

 so on, as any one may try by placing a spider at the bottom 

 of a very clean wine glass. 



The hairs of the legs, however, are always catching bits 

 of web and particles of dust; but these are not suffered 

 to remain long. Most people may have remarked that the 

 house-fly is ever and anon brushing its feet upon one 

 another to rub off the dust, though we have not seen it 

 remarked in authors that spiders are equally assiduous in 

 keeping themselves clean. They have, besides, a very 



* Spectacle de la Nature, i. 58. 



t Linn. Trans, vol. xv. 



