Superfamily Argiopoidea 



as a single thread in Fig. 285; but its double nature is shown in 

 the part not covered with the hackled band near the outer end 

 of each line (Fig. 284); each of the two parts of this double thread 

 consists of several parallel strands; this can be seen by slight 

 magnification of that part where it is flattened near the attach- 

 ment disk. Second, — the primary looped threads; there are two 

 of these, and they form the axis of the hackled band; they are 

 extremely elastic. Third, — the secondary looped threads; there 

 is one of these supported by each of the two primary looped 

 threads; each of the secondary looped threads forms a very 

 regular series of loops, each of which is fastened by one end to the 

 primary looped thread; this secondary thread is not looped around 

 the primary thread as it appears to be, but is merely fastened 

 to one side of it by viscid silk. Fourth, — the viscid silk; this is 

 an amorphous sheet, which fills the spaces between the loops of 

 the secondary looped thread; it is largely liquid, but when it 

 is highly magnified irregular threads can be seen in it. 



It is easy to infer the function of these four kinds of silk: 

 the supporting line not only supports the parts fitted for entangling 

 the prey but communicates to the centre of the web, where the 

 spider is lying in wait, any disturbance of the web; the primary 

 looped threads also have two functions, they support the secondary 

 looped threads and by their elasticity allow an entangled insect 

 to become involved in other threads; I have seen these threads 

 stretch to fifty times their first length; the secondary looped 

 threads support the viscid silk; and the viscid silk clings to any- 

 thing that touches it. 



An interesting prob.em to be solved is the determination of 

 the source of each of the four kinds of silk in the hackled band 

 and its support, and the method of spinning the hackled band. 

 The doubling of the supporting thread shows that it is spun 

 separately. In the upper part of Fig. 284 are shown several 

 places where the two parts of the supporting thread are widely 

 separated; in these cases the spiders did not return to the starting 

 point after making the attachment disk. It seems probable 

 that when the hackled band is applied to this supporting thread 

 the primary loops are made by a movement of the spinnerets, 

 and that at the same time the secondary loops are formed by 

 the calamistrum. During this operation silk is issuing from four 

 spigots; from two of them comes the elastic silk that forms the 



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