Microscopical Essays, 329 



tubes or cafes. They are, in general, fo final I, that it is not eafy 

 to diftinguifh the cafes without a magnifier; but as the body 

 lengthens., the cafe becomes too fhort ; it is, therefore, part of it's 

 daily employ to lengthen the cafe. For this purpofe, it extends 

 the head beyond the tube, and having found the materials which 

 anfwer it's purpofe, it tears it off, and brings it to the end of the 

 tube, and fixes it there, repeating this manoeuvre till it has fuffi- 

 ciently lengthened it ; after it has finifhed one end, it turns itfelf 

 round within the cafe, and performs the fame operation at the 

 other. 



This does not terminate their labours, for the tube mud alfo be 

 increafed in diameter, as it foon becomes too fm all for the body; 

 the means they make ufe of to enlarge it, is prccifely the fame as 

 we ourfelves mould adopt under fimilar circumflances. The in- 

 feci: flits the tube at the two oppofite fides, at the fame end, and 

 inferts in the flit two pieces of the required fize ; it then performs 

 the fame at the other end. By this means they foon enlarge it 

 fufficiently, without expofing themfelves to the air during the 

 operation. The outfide of thefe cafes is made of filk, hair, Sec. 

 The infide is of filk only. Their covering always partakes of the 

 colour of the cloth, or tree, &c. from whence it was taken. If 

 it paries over a red piece, the colour will be red.. When they 

 are come to their perfect growth, they abandon the cloth, and 

 leek for a proper' place wherein they may pafs from their prefent 

 to a more perfect flate. 



I cannot conclude this long chapter better than in the words of 

 Mr. Stillingfleet. " Many are apt to treat with contempt any 

 hi an whom they fee employed in poring over a mofs, or examin- 

 6 ' irig 



