100 



AMERICAN SPIDERS AND THEIR SPINNINGWORK. 



a motion which causes the threads to rapidly contract and gather into a 

 little ball of loops near the surface of the web. (Fig. 92.) The spider then 

 swings her abdomen well to one side of this flossy hump of loops, as at 

 Fig. 93, drawing after her a ray of milky filaments. Next, she draws back 

 her abdomen, which is held close to the shield space, pulls the taut lines 

 over the flossy mass (Fig. 94), and the spinnerets are then 

 moved back and forth with a lateral motion like the 

 spreading of mortar by a mason's trowel, thus pushing, 

 beating, or spreading the loops against the cross lines of 

 the hub. The spider repeats these motions, at the same 

 time shifting her position occasionally, thus revolving her- 

 self by her feet around the circle of the shield. As the 

 spinnerets, of course, revolve with the body, the weaving 

 process is continually repeated, and the shield gradually 

 FIG. 93. A third position, formed. The movement of the spinnerets is from the 

 to one side, drawing centre of the hub outward, and it follows that as the 

 out a second ray of g rea test quantity and thickness of silk issue at the first 



spinning lines. J . . 



expulsion and gradually diminish, the centre receives 

 the heaviest coating, and this decreases toward the margin. The fact that 

 the shield is more closely woven in the centre is thus accounted for. 



This describes the ordinary method by which Argiope's shield is spun, 

 but there are other modes. One continually finds, in studying the new made 

 webs of this species, that the zigzag ribbon entirely traverses the hub, in 

 which there is no trace of the shield except a few straggling lines. In this 

 case the ribbon has evidently been spun first. Again, one sees the same 

 extended ribbon, and, in addition, on either side are woven one or more 

 zigzag bands, arranged in arcs of circles, which occupy the 

 space usually taken by the shield. In the course of time 

 these would be overspun, so that the hub would be occu- 

 pied by the thick shield which is common to the species. 



When the hub is covered over, the spider proceeds to 

 insert her zigzag ribbon. She moves downward to a point 

 a little below the shield. Dropping her spinner- 



ets to one of the radii, she attaches all the num- 



Insertion 



' erous filaments at once, say at the point 1, Fig. 



_. ni ,-i -111 11" i FIG. 94. Fourth position; 



95. She then raises her abdomen and begins to ascend, the abdomen returned 

 moving slowlv, and dragging after her a band of silk. to th e looped masses, 



Xl which the spinnerets are 



As she mounts, she swings her spinnerets across to the oppo- beating and squeezing 

 site radius, drops them at the point 2, and attaches her down - 

 ribboned dragline thereto. Of course, the upward movement of the spider 

 and the simultaneous lateral motion of her spinnerets give to the ribbon a 

 diagonal course, so that the second point of attachment, 2, will be higher 

 than the first point, 1. So also when the abdomen is swung back again, the 

 spider meanwhile still climbing, the third point, 3, will be higher than the 



