Nefs of Geoinetric Spiders 183 



now to be spun from the circumference around the centro, which may be 

 regarded as constituting the most important part of the snare. It con- 

 sists of a fine thread closely studded with minute dew-like globules, easily 

 separable from each other by extending the elastic filament on which 

 they are arranged. They are, in fact, globules of viscid gum, as is proved 

 by their adhering to the finger and retaining dust thrown upon the net, 

 while the unadhesive radii and exterior threads remain unsoiled. These 

 viscid threads alone retain the insects which fly into ths net, and as they 

 lose their adhesive property by the action of the air, it is requisite that 

 they should be frequently renewed, a process not neglected by the Spi- 

 der, which evinces a perfect consciousness of its necessity. Placing her- 

 self at the circumference of the net, and fastening her viscid thread to the 

 end of one of the radii, the Spider walks up that radius towards the cen- 

 tre, till she comes in contact with the last produced circumvolution of the 

 unadhesive spiral line, along which she passes to the adjoining radius, 

 drawing out the thread in her transit with the claws of the hind leg 

 nearest to the circumference. She then transfers the thread to the claws 

 of the other hind leg, and passing down the radius at which she has just 

 arrived towards the circumference, she places the foot of the hind leg 

 previously employed in drawing out the thread, on that point in the ra- 

 dius to which her filament is to be attached, and bringing the spinners to 

 the spot there makes it secure. The precise place in each radius at 

 which to fix the thread, is always ascertained by the situation of the foot 

 of the hind leg, and this is determined by touching with the feet of those 

 legs nearest the circumference, the marginal line, or, when the structure 

 of the net is further advanced, the last-formed circumvolution of the viscid 

 spiral line. As this last line approaches the several circumvolutions of 

 ihe unadhesive spiral line, the Spider bites them away, being sensible 

 tliat they are no longer of any use to her, and this fact explains why they 

 are never seen intermixed with the circumvolutions of the former in 

 finished nets. The viscid spiral line, whose circumvolutions are nearly 

 equidistant, being separated by a space of one or two lines, is thus pro- 

 duced till it extends to the most proximate circumvolutions of the unadhe- 

 sive spiral line, which occupying the central part of the net are suffered 

 to remain ; it is then discontinued, and the Spider making choice of some 

 retired spot in the vicinity, there constructs a cell in which she may con- 



