THE SILKWORM ITS FORM AND LIFE HISTORY. 21 



the mandibles, and are called maxilla. They have not the power 

 of the mandibles, being far less strong and hard, and less freely 

 movable, and thus are used chiefly to direct the course of the 

 bitten pieces till they enter the mouth, in which function each 

 maxilla is assisted by a jointed organ called a palpus, attached 

 to its side. 



Between the two maxillae is an organ called the lab turn, or lower 

 lip, in the middle of which, below, is a rounded projection, the 

 spinneret, from a minute hole in the centre of which the silk 

 issues, when required. The mouth itself is a small opening 

 situated between the mandibles and maxillae, and is bounded 

 below by the labium, and above by the labrum. When food is 

 taken, the leaf is held between the front legs, with its edge turned 

 towards the body ; then the head is raised till it reaches as far up 

 the edge of the leaf as possible ; the mandibles are then opened 

 and brought down upon the leaf with a powerful stroke, then 

 opened again while the head is caused to descend a little, where- 

 upon another snip is taken, then another and another in quick 

 succession, the head being moved a little down towards the under 

 surface of the body after each bite. Meanwhile, the maxillae and 

 their palpi do their work behind, and the snipped-off pieces are 

 rapidly passed into the mouth. From this it is evident that the 

 bitten edge of the leaf will present the form of a semi-circle, or 

 some smaller, but regular, curve. When one series of bites has 

 been finished, the head is again raised, and another series of 

 nibbles made in curved fashion as before, and so on till the meal 

 is finished. 



One more pair of organs is all that remains to complete the 

 the equipment of the head. These are the two antenna, which 

 are small cylindrical bodies, terminated by a long hair and jointed 

 to the head near the eyes. They appear to be organs of sense 

 of some kind. 



Down each side of the body, there will be noticed a row of nine 

 small oval black rings, one on each segment, except the second, 

 third, and twelfth. These enclose little openings into the body, 

 which constitute the entrances to the breathing organs. The 

 black ring surrounds a white space, down the longest diameter 

 of which runs vertically a straight slit ; this is the entrance referred 

 to. Caterpillars, curiously enough, take in the air they require 

 for breathing purposes, not through any part of the face, as we 

 do, but through these slits in the sides, which are therefore called 

 spiracles, i.e., breathing holes, and the dark spots that surround 

 them are called stigmata, each being a stigma. These minute 

 slits are the entrances to little tubes, or trachea, which run hither 



