112 



FIRST BOOK OF ZOOLOGY. 



large spiders can be easily seen withciut the aid of a magni- 

 fying-glass. 



103. The abdomen has little appendages at its hinder end 

 called spinnerets, and from these the spider produces the 

 thread with which it builds its nests and nets, the nets being 

 commonly called spiders' "webs. 



Highly magnified the spinnerets appear as blunt protu- 

 berances arranged together in pairs, and capable of being 

 contracted or expanded. These spinnerets are covered 

 with hundreds of jointed hairs which are perforated and 

 through which the web-forming material escapes. This ma- 

 terial is fluid and something like the white of an egg. 

 Escaping from the body, through hundreds of these minute 

 openings, the strands of this fluid diy almost instantly, and, 

 uniting, form the delicate, yet comparatively strong, thread of 

 the spider. Thus it will be seen that the thread of the 

 spider is composed of hundreds of strands, which may be 

 often separated just as the fibres of a rope may be pulled 

 apart. Under the microscope the posterior end of the abdo- 

 men with the spinnerets looks like this. 



FIG. 109. SFINNEKETS OF A SPIDER. , one of the Tubular Hairs from the Spinneret8, highly 



magnified. 



