344 INSECT ARCHITECTURE. 



or some projecting body, and there fastens her thread; 

 after which, with her two hind feet, she squeezes her 

 dugs {spinnerts), and presses out one or more 

 threads of two or three ells in length, which she 

 leaves to float in the air till it be fixed to some par- 

 ticular place."* Without pretending to have ob- 

 served this, Swammerdam says, " I can easily compre- 

 hend how spiders, without giving themselves any 

 motion, may, by only compressing their anus, spin 

 out a thread, which being driven by the wind, may 

 serve to waft them from one place to another. "| 

 Others, proceeding upon a similar notion, give a 

 rather different account of the matter. " The spider," 

 says Bingley, " fixes one end of a thread to the place 

 where she stands, and then with her hind paws 

 draws out several other threads from the nipples, 

 which, being lengthened out and driven by the wind 

 to some neighbouring tree or other object, are by 

 their natural clamminess fixed to it. "J 



Observation gives some plausibility to the latter 

 opinion, as the spider always actively uses her legs, 

 though not to draw out the thread, but to ascertain 

 whether it has caught upon any object. The notion 

 of her pressing the spinneret with her feet must be a 

 mere fancy ; at least it is not countenanced by any 

 thing which we have observed. 



4. An opinion much more recondite is mentioned, if 

 it was not started by M. D'Isjonval, that the floating 

 of the spider's thread is ellectrical. " Frogs, cats, 

 and other animals," he says, " are effected by natural 

 electricity, and feel the change of weather; but no 

 other animal more than myself and my spiders." 

 During wet and windy weather he accordingly found 

 that they spun very short lines, " but when a spider 



* Spectacle de la Nature, vol. i. 

 t Book of Nature, part i. p. 25. 

 J Animal Biography, vol. iii. p. 475, Srd edition. 



