282 Silk Manufacture. 



the animal arrives at his destination. It is not often that the 

 organ is put to this use, as the pinna is but httle addicted to loco- 

 motion : some naturalists indeed affirm that it is always stationary. 

 The use to which the tongue is most frequently applied is that of 

 spinning the threads. Although this body is flat, and similar in 

 form to a tongue through the greater part of its length, it becomes 

 cylindrical about the base or root, where it is much smaller than 

 in any other part : at this lower end are several ligatures of a mus- 

 cular nature, which hold the tongue firmly fixed against the middle 

 of the shell ; four of these cords are very apparent, and serve to 

 move the tongue in any direction according to the wants of the 

 fish. Through the entire length of this member there runs a slit, 

 which pierces very deeply into its substance, so as almost to di- 

 vide it into two longitudinal sections ; this slit performs the office 

 of a canal for the liquor of which the threads are formed, and 

 serves to mould them into their proper form : this canal appears 

 externally like a small crack, being almost covered by the flesh 

 from either side, but internally it is much wider, and is surrounded 

 by circular fibres. The channel thus formed extends regularly 

 from the tip to the base of the tongue, where it partakes of the 

 form of the member and becomes cylindric, forming there a close 

 tube or pipe in which the canal terminates. The viscid substance 

 is moulded in this tube into the form of a cord, similar to the 

 threads produced from it, but much thicker, and from this cord 

 all the minute fibres issue and disperse. The internal surface of 

 the tube in which the large cord is formed is furnished with glands 

 for the secretion of the peculiar liquor employed in its production, 

 and which liquor is always in great abundance in this animal as 

 well as in muscles. 



' Reaumur observed, that although the workmanship, when 

 completed, of the land and sea animals, is the same, the manner 

 of its production is very different. Spiders, caterpillars, and the 

 like, form threads of any required length, by making the viscous 

 liquor of which the filament is formed pass through fine perfora- 

 tions in the organ appointed for this spinning. But the way in 

 which musclps form their thread is very diffijrent ; as the former 

 resembles the work of the wire-drawer, so does the latter that of 

 the founder who casts metals in a mould. The canal of the organ 

 destined for the muscle's spinning is the mould in which its thread 

 is cast, and gives to it its determinate length. 



' Reaumur learned the manner of the muscle performing the 

 operation of spinning by actually placing some of these fish under 

 his constant inspection. He kept them in his apartment in a ves- 

 sel filled with sea water, and distinctly saw them open their shells 



