ORB-WEBS 



347 



to which the spider can put in the viscid spiral, which it com- 

 mences at the circuivferencc. 



Its action now becomes exceedingly careful and deliberate, 

 though by no means slow, and so great is its absorption in the 

 work that it may be observed quite closely with a hand-lens 

 without fear of interrupting it. The proceeding consists in 

 drawing out from its spinnerets with one (or both) of its hind 

 legs successive lengths of a highly elastic line, which it stretches 

 just at the moment of fixing it to a radius, and then lets go 

 with a snap. There is no hesitation or pause for consideration, 

 but there is a peculiar deliberateness in drawing out each length 

 of the thread which, together with stretching and sudden re- 

 lease, require explanation. Now, it has already l^een mentioned 

 that the framework and radii of the snare are not at all moist or 

 adhesive. This, however, is not the case with the spiral, upon 

 which the spider chiefly relies in capturing its prey. A close 

 examination of it — even with the naked eye — will show it to 

 be beaded over with little viscid globules which, under a low 

 magnifying power, are seen to be arranged with remarkable 

 regularity. 



A very convenient method of investigation is to carry off a 

 newly-constructed web — or, better still, one not quite finished — 

 on a piece of plate glass, to which it will adhere by reason of 

 the viscid spiral, and on which it may be examined at leisure. 



Fig. 190. — A, B, C, D. Stages in tlie formation of the viscid globnles of the web. 



Immersion in a staining fluid will colour the viscid spiral, and 

 show its structure in a striking manner. It will appear to con- 

 sist of a thread strung with beads of two sizes, occurring with 

 pretty uniform alternation, though two of the larger beads are 

 often separated by two or more of the smaller. 



Until recently it was supposed that the deposition of these 

 beads upon the spiral line was a subsequent operation, and, in view 



