The Life of Spiders 



When highly magnified this viscid and elastic line is seen 

 to be composed of two elements (Fig. 181): first, the axis of the 

 thread consisting of two strands; and second, a series of globular 

 drops borne upon this axis; the axis is the elastic element of the 

 thread and the drops the viscid portion. In the webs of some of 

 our larger spiders, the viscid drops on the spiral line can be seen 

 with the unaided eye (Fig. 185). 



It is evident that the elastic thread is spun from two spigots; 

 but as yet I have been unable to locate these spigots and con- 

 sequently have not traced the silk back to the glands producing 

 it. The viscid thread appears to come from the centre of the 

 group of spinnerets; this may indicate that one of its elements 

 is produced by the ampullate glands that open on the middle 

 spinnerets; if this is so it is probably the elastic portion that is 

 so produced. I can see no foundation for the belief of Apstein 

 ('89, p. 40) that the central part of the viscid thread is produced 

 by the aciniform glands; these open through small spinning tubes 

 and produce fine threads like those of the swathing band. 



The silk of which the viscid drops are composed is believed 

 to be secreted by the aggregate or treeform glands which open 

 through spigots on the hind spinnerets (Apstein '89, p. 39). This 

 silk is poured forth upon the elastic thread in a continuous sheet; 

 but it breaks up into drops almost immediately, a result of the 

 surface tension of the liquid. I have observed, when watching 

 a large Aranea gigas spin its viscid spiral, that the thread as it 

 was pulled from the spinnerets was smooth; but an instant later, 

 the viscid drops appeared on that part of this section that had 

 been put in place between two radii. It should be noted, however, 

 in this connection, that the smooth portion of the thread, the 

 section between the spinnerets and the radius to which it was 

 fastened last, is greatly stretched; and that as soon as it is fastened 

 to another radius, this tension is relaxed, which would result 

 in a massing of its outer coat, and thus facilitate the formation 

 of the drops. 



The hackled hands. — By the term hackled hands may be des- 

 ignated the distinctively characteristic J: h reads spun by spiders 

 having a cribellum and a calamistrum. 1 suggest the term band 

 for these threads because they are flat and more or less ribbon- 

 like structures. This feature, however, is only apparent when they 

 are greatly magnified; to the unaided eye they appear as threads. 



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