NATURE'S CRAFTSMEN 



To begin with the manufacture of the raw material, 

 one must go to the silk glands. These lie in an orderly- 

 mass in the lower part of the apex of the abdomen, and 

 consist of a large number of glands of several shapes 

 and sizes. Many are pear-shaped (pyriform), some are 

 "tree-formed," some are cylindrical or vermiform. 

 Within these are secreted several kinds of liquid silk 

 and the substance that forms the viscid beaded arma- 

 ture of the spiral lines of the orbweb. 



Argiope is able to secrete at least three colors of silk 

 stuff — the white, which forms the web, and the en- 

 swathement of captives and the egg-cocoon; the brown 

 mass that fills the cocoon interior; and the flossy yellow 

 between that and the inside of the sac. The glands end 

 in minute ducts which empty into spinning-spools regu- 

 larly arranged along the sides upon the tips of the six 

 spinnerets, or "spinning-mammals," or "spinning-fin- 

 gers," which are placed just beneath the apex of the 

 abdomen. The spinnerets are movable and can be 

 flung wide apart or pushed closely together, and the 

 spinning-spools can be managed in the same way. 



The silk glands are enfolded in muscular tissue, press- 

 ure upon which, at the will of the spider, forces the 

 liquid silk through the duct into the spool, whence it 

 issues as a minute filament, since it hardens upon con- 

 tact with the air. One thread, as seen in a web, may be 

 made up of a number of filaments, and is formed by put- 

 ting the tips of the spools together as the liquid jets are 

 forced out of the ducts. When the spinnerets are joined 

 and a number of the spools are emptied, at once their 

 contents merge, and the sheets or ribbons are formed 

 which one sees in the enswathement of a captive or the 

 making of Argiope's central shield. This delicate and 



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