178 THE WONDERS OF INSTINCT 



continual contact with those threads might produce a 

 certain adhesion and inconvenience to the Spider, who 

 must preserve all her agility in order to rush upon the 

 prey before it can release itself. For this reason, gummy 

 threads are never used in building the post of intermin- 

 able waiting. 



It is only on her resting-floor that the Epeira sits, mo- 

 tionless and with her eight legs outspread, ready to mark 

 the least quiver in the net. It is here, again, that she 

 takes her meals, often long-drawn-out, when the joint is 

 a substantial one; it is hither that, after trussing and 

 nibbling it, she drags her prey at the end of a thread, to 

 consume it at her ease on a non-viscous mat. As a hunt- 

 ing-post and refectory, the Epeira has contrived a cen- 

 tral space, free from glue. 



As for the glue itself, it is hardly possible to study its 

 chemical properties, because the quantity is so slight. 

 The microscope shows it trickling from the broken 

 threads in the form of a transparent and more or less 

 granular streak. The following experiment will tell us 

 more about it. 



With a sheet of glass passed across the web, I gather 

 a series 3f lime-threads which remain fixed in parallel 

 lines. I cover this sheet with a bell-jar standing in a 

 depth of water. Soon, in this atmosphere saturated with 

 humidity, the threads become enveloped in a watery 

 sheath, which gradually increases and begins to flow. 

 The twisted shape has by this time disappeared ; and the 

 channel of the thread reveals a chaplet of translucent 

 orbs, that is to say, a series of extremely fine drops. 



