The Life of Spiders 



least, if not usually, the spider returns to the centre along the 

 radius just made and spins a line which it does not hold clear 

 and which adheres to the radius, thus doubling it. In some ob- 

 servations that I have made it was easy to see that the radius 

 was thicker behind the spider than in front of it. As the drag- 

 line consists of two lines, when a radius is doubled it consists of 

 four; this was well shown in the photograph from which Fig. 

 192 was made. 



The hub — -The centre of the web, where the radii converge, 

 is strengthened by a mesh or net-work of lines termed the huh. 

 A part of the hub is made while the radii are being stretched, 

 the spider working a little on the hub on each return to the 

 centre of the web; after all the radii are stretched the hub is 

 completed. 



The nature of the hub of the webs of different species of spiders 

 differs greatly and forms one of the distinctively characteristic 

 features of them. Three types of hubs were named by McCook 

 ('89 I. 54); these are the meshed huh, the sheeted hub, and the open 

 hub. 



The meshed hub is formed of a series of irregularly shaped 

 meshes, through which one can often trace the continuation of 

 the radii as zigzag lines; the radii being pulled out of their direct 

 course in the making of the hub. In some webs there is but little 

 regularity in the meshes of the hub (Fig. 185); but in others 

 the hub is a very beautiful structure. 



The sheeted hub consists of a closely woven sheet of silk spun 

 upon the net-work. This type is well-shown in the webs of 

 Metargiope (Fig. 188). 



The open hub resembles the hub of a wagon, in being a firm 

 structure supporting the spokes or radii and having an open space 

 in the centre (Fig. 189). This type of hub is characteristic 

 of the webs of Micrathena and of those of the Tetragnathidae. 



The notched \one. — Immediately outside of the hub there is 

 an area in which there are a few turns of a spiral line; the number 

 of these turns varies from four or five or even less to ten or more. 

 In spinning this line, which is done immediately alter the hub is 

 made, the spider attaches it to each radius lengthwise tor a short 

 distance instead of crossing the radius at right angles. Hie pulling 

 of the line taut between the radii pulls them out of their direct 

 course and gives to this area the appearance that suggested the 



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