SPINNING APPAKATUS OF GEOMETRIO SPIDERS. 35 



strung upon a thread with remarkable regularity, as shown in 

 fig. 14 d. 



It was until a few years ago supposed that these globules 

 were separately deposited by the spider, whereas a uniform 

 coating of viscid matter is given to the thread in the first in- 

 stance, and its subsequent subdivision into globules is an 

 entirely physical phenomenon. Boys^ well describes the spider's 

 action as follows : 



" The spider draws these webs slowly, and at the same time 

 pours upon them a liquid, and, still further to obtain the effect 

 of launching a liquid cylinder into space, he pulls it out like 

 the string of a bow, and lets it go with a jerk." 



That this separation into globules is really a secondary 

 phenomenon 1 have shown by taking upon a slide a portion of 

 such a spiral immediately upon its completion. It readily 

 stains with hsematoxylin, and on microscopic examination 

 shows the various stages indicated in fig. 14. 



We have thus separately to consider the ground-line (Grund- 

 faden, Apstein) and the viscid matter with which it is en- 

 veloped. 



Apstein imagines the ground -line to be furnished by the 

 Aciniform glands, and to be many- stranded. 



I have not yet succeeded in tracing it with certainty to its 

 origin, but have established the following facts with regard 

 to it : 



In the first place, it is not many-stranded, but double 

 only. 



When engaged upon this line the creature is so absorbed as 

 to allow of pretty close examination with a hand-lens, I have 

 at such times noticed that the posterior spinnerets are partly 

 open, and that the line is, at first, distinctly double, fusing, by 

 virtue of its viscid envelope, where grasped by the leg which 

 draws it forth. Moreover, on staining and teasing the spiral 

 line, the ground thread readily shows its double nature (fig. 

 15), but no amount of teasing breaks it up into further strands, 

 as would surely be the case if such existed, for their separate 



1 " Quartz Fibres," by C. V. Boys, F.R.S., ' Nature,' July 11, 1889. 



