182 Mr. Blackwall on the Construction of the 



in places where the insects they prey upon abound. After selecting a 

 suitable situation for her purpose, the Spider's first operation, in most in- 

 stances, is to enclose an area, the figure of which appears to be a matter 

 of indiflference, with lines of her own spinning. This is effected by pro- 

 ceeding along the objects immediately surrounding the space destined to 

 be occupied by the net, and attaching to several points, by pressing the 

 spinners against them, a line drawn out after her in her transit from one 

 to another. These marginal lines she strensjthens with a few additional 

 ones, and finally gives them the requisite degree of tension by applying 

 to them in different directions numerous smaller threads. Having thus 

 completed the foundations of her snare, in the next place she commences 

 to fill up the outline. Fixing a thread to one of the boundary lines, along 

 which she walks, she guides the filament produced in her progress with 

 one of her hind feet, that it may not touch in any part and adhere pre- 

 maturely; and crossing over lo the opposite side, she there attaches it 

 firmly by applying her spinners. To the middle of this diagonal thread, 

 which is to form the centre of the net, she fixes a second, which in like 

 manner she conveys and fastens to another part of the lines encompass- 

 ing the area. Along this last-formed thread she returns, drawing out 

 another after her, which, as she does not employ any means to keep it 

 distinct, becomes connected with that on which she is advancing, and is 

 ultimately glued by its extremity to the centre of the net. In this man- 

 ner, but without observing any regularity in the order of her progression, 

 she forms about twenty or thirty radii, composed of double lines, diverg- 

 ing from the centre to the circumference, and giving the net the appear- 

 ance of a wheel. She then proceeds to the centre, turns herself round, 

 and pulls each radius with her feet to ascertain its strength, breaking such 

 as seem defective and replacing them by others. Her next proceeding is 

 to produce, round the centre of the net, a spiral line extending thence to 

 the circumference, and intersecting the radii, to which she attaches it by 

 pressing her spinners against them. This spiral line, a few of the more 

 central circumvolutions of which are much nearer to each other than are 

 those removed to a greater distance from that point, serves as a temporary 

 scaffolding for the Spider to walk over, and also to keep the radii properly 

 stretched during her succeeding operations. It, together with the radii 

 and marginal lines, is composed of unadhesive silk ; but a spiral line has 



