448 SUPPLEMENT 



it has fixed a great number in this direction; after this, it 

 places more in an opposite line ; and as all these threads are 

 gluey, they become cemented one to the other, and soon form 

 a tolerably solid web. 



The Epeira diadema, which makes a perpendicular web 

 with radii, and the threads of which lead to a common centre, 

 proceeds in another fashion. According to the majority of 

 authors, it suffers itself to hang to its thread, and the wind 

 carries it to a tree different from that to which it was at first 

 attached ; it there applies one end of its thread. This done, 

 it returns to the middle of this thread, along which it walks, 

 whei'e it attaches a second, the extremity of which it fastens to 

 some branch near the first, and so on. The opinion of Lister 

 is, that the arane'ides can shoot their threads to a very great 

 distance, as the porcupine shoots his quills, with this difference, 

 however, that the quills of the porcupine are detached from its 

 body, whereas the threads of the arane'ides remain attached. 

 This opinion has been combated. People have been unable 

 to conceive that the silk, which hai'dens in the air, can be 

 syringed in this manner, like a fluid. Besides, it has been 

 contended, that so weak a thread could not be shot any dis- 

 tance without being forced by the resistance of the air to fold 

 upon itself, and envelope the body of the animal. Be this, 

 however, as it may, M. Latreille has very distinctly observed 

 the Aranea cancer turning on itself, and dartingin all directions, 

 in a horizontal line, a thread proceeding from the anus. 



We shall now explain how the Epeira diadema makes its 

 web between two branches, or two trees, separated from each 

 other by a ditch, or by a stream which it cannot cross. In 

 calm weather, placed at the end of some branch, it remains 

 firm on its front feet, and with its two hinder feet it draws 

 from its nipples a thread, tolerably long, which it suffers to 

 float in the air. This thread is pushed by the wind against 

 some solid body, where it is quickly cemented by its natural 



