ARACHNIDA. 255 



eiitanoie flies and other small insects. Every 

 species of spider weaves its web in a manner pecu- 

 liar to itself: and, besides the principal web, they 

 often construct in the neighbourhood a smaller one, 

 in the form of a cell, in which they conceal them- 

 selves, and lie in ambush for their prey. Between 

 this cell and the principal web they extend a thread 

 of communication, and by the vibrations into which 

 it is thrown, on the contact of any solid body, the 

 spider is immediately acquainted with the event, 

 and, by the assistance of the same thread, passes 

 quickly to the spot. 



Some species have the power of conveying them- 

 selves to considerable distances through the air by 

 means of threads which they dart out, and which 

 are borne onwards by the wind, while the spider is 

 clinging to the end of the thread which is next to it. 

 In this manner these spiders are often carried up 

 to a great height in the air : and it has been sup- 

 posed that during their flight they seize upon gnats 

 and other flies ; because the mutilated remains of 

 these insects are often seen adhering to the threads : 

 this point, however, is still open to much doubt. 

 Spiders apply this power of manufacturing threads 

 in various ways, not only for entangling and bind- 

 ing their victims, but occasionally also for effecting 

 their escape from situations of peculiar difficulty.* 



* A remarkalile instance of a manoeuvre of this kind is thus re- 

 lated by Mr. T. Bell ; " I insulated a common house-spider, (Ara- 

 nea domestica), by placing it on a little platform, supported by a 

 stick with a weight at the bottom, in the middle of a rummer of 

 water. The platform was about half an inch above the surface, 

 which was nearly even with the top of the glass. It presently 

 made its escape, as was anticipated, by suffering a thread to be 

 wafted to the edge of the glass ; but, supposing that it might have 



