828 



THE NATURE BOOK 



ONE OF THE SPINNERETS GREATLY MAGNIFIED 

 TO REVEAL THE MINUTE TUBES FROM 

 ■WHICH THE SILK IS EMITTED. 



to the leaves and stems of plants and other 

 objects ; and thus by a gradual perfection 

 of the primitive form in the course 

 of ages may have finally evolved 

 the marvellously constructed snares, 

 with all their comphcated details, 

 which are so common where the 

 Spider conducts his nefarious trade. 

 The snares of the web-weavers 

 are the more astonishing when 

 we consider their details. A 

 glance at the illustration of the 

 web of a Garden Spider (p. 829) 

 will show that the meshes are 

 formed by two kinds of threads. 

 There are, first, the radiating 

 threads, and then woven over these 

 are numerous concentric threads. 

 When the Spider moves about her 

 snare it will be found that, as far 

 as possible, she avoids the concen- 

 tric threads, for these are contrived 

 with diabolical ingenuity (I use 

 that oxpressi(jn figuratively) fur the 

 capture of her victims. 



The framework of the snare is composed 

 of plain, strong strands, but the con- 

 centric threads are studded along their 

 length with large and small viscid globules 

 (see illustration on p. 830) ; indeed, the 

 snare is not only a net in which to catch 

 unwary flies, but a veritable bird-hme 

 trap which hopelessly entangles them as 

 they struggle to effect their escape. 



Within the abdomen of the Spider are 

 several powerful glands of various forms 

 which secrete the viscid fluid from which 

 the web is constructed. These glands are 

 connected with the spinnerets at the hinder 

 part of the abdomen ; an enlarged view of 

 these organs is given on this page. 



As the illustration shows, there are six 

 spinnerets in the case of the Garden 

 Spider. Each of these organs is crowned 

 with numerous minute tubes of great 

 dehcacy, and from these issue the silken 

 strands. One of the spinnerets is also 

 here shown further magnified to exhibit 

 these tiny tubes. In the construction of 

 a thread, the silk may be drawn from a 

 few or from all of the tubes of a spinneret, 

 according to the strength required. 



The silk from the various glands un- 

 doubtedly differs in character. I have 

 stated that the framework of the snare 

 consists of plain radiating spokes or 

 strands, and I may now add that, 

 when formed, they harden rapidly on 



A MAGNIFIED VIEW OF THE SPIDER'S SPINNERETS. 



