310 INSECT ARCHITECTURE. 



admirable treatise of Lyonnet on the anatomy of the 

 Cossus, will render these several organs more easily 

 understood than any description. 



The spinneret itself was supposed by Re'aumur to 

 have two outlets for the silk ; but Lyonnet, upon 

 minute dissection, found that the two tubes united 

 into one before their termination ; and he also almost 

 assured himself that it was composed of alternate 

 slips of horny and membranaceous substance, — the 

 one for pressing the thread into a small diameter, and 

 the other for enlarging it at the insect's pleasure. It 

 is cut at the end somewhat like a writing-pen, though 

 with less of a slope, and is admirably fitted for being 

 applied to objects to which it may be required to 

 attach silk. The following are magnified figures of 

 the spinneret of the Cossus from Lyonnet. 



TI&} / 



Side view of the Silk-tube. Section of the Sili-tube, magnified 

 22,000 times. 



" You may sometimes have seen," says the Abbe 1 

 de la Pluche, " in the work-rooms of goldsmiths or 

 gold-wire drawers, certain iron plates, pierced with 

 holes of different calibres, through which they draw 

 gold and silver-wire, in order to render it finer. The 

 silk-worm has under her mouth such a kind of instru- 

 ment, perforated with a pair of holes [united into one 

 on the outside*], through which she draws two drops 

 of the gum that fills her two bags. These instruments 



* Lyonnet. 



