SPINNING APPARATUS OF GEOMETRIC SPIDERS. 67 



tlie observation of the animal when employed naturally in its 

 various spinning operations. Here the difficulties experienced 

 were considerable, but some results were obtained by the aid of 

 a simple contrivance, consisting of a pair of compasses with the 

 points fixed some two inches apart, and between them a narrow 

 strip of cloth stretched. 



A flat piece of wood was held behind the spider while at 

 work, and between this and the strip of cloth the creature 

 was suddenly trapped, the points of the compasses, which pro- 

 jected the eighth of an inch beyond the cloth, being buried in 

 the wood on either side. 



Flies were now placed in the various webs, and the spiders 

 seized in the act of binding them up in the usual manner. The 

 fly is held and rotated by means of the jaws, palps, and ante- 

 rior legs, while the fourth pair of legs draw up from the spin- 

 ners the bands of silk which are to enclose it. These silken 

 bands were found to be constituted as shown in figs. 13 or 13. 

 There seems no doubt, therefore, that the Aciniform 

 and Piriform glands are mainly used in performing this 

 operation. 



The structure of the geometric snare was next investigated. 



This is a familiar object, and may be said to consist of — 



(1) a sort of frame or scafi'olding, to which are attached 



the distal ends of 



(2) the radial lines ; 



(3) the spiral line, extending from the periphery to near 



the centre. 



(1) The thread of the framework was generally found to be 

 composed as exhibited in fig. 11. When necessary the spider 

 strengthened the line by repeating the journey, and laying it 

 down a second time. 



(2) The same line, or that of fig. 10, was also employed in 

 constructing the radii of the snare. 



Thus the framework and radii of the geometric web are 

 supplied by the Ampullaceal glands. 



(3) The spiral line requires a more detailed description. 



A low power shows it to consist of bead-like viscid globules 



