INSECTS: THEIR MOUTHS 183 



This specimen shows very distinctly that the two sides 

 are but semi-tubular, and as one pair of the opposing edges 

 are open at each extremity, and the other pair separate 

 throughout, we are able to discern very clearly the array 

 of hooks, by which the edges are united at the will of the 

 animal. No trace of the curious little pointed barrel- 

 shaped papillae is found here, but I have seen it in other 

 examples. 



It seems highly probable, from the observations of the 

 excellent anatomist just named, that the exhaustion of the 

 nectar of a flower, which is effected with great rapidity 

 and completeness, is a process dependent on respiration, 

 and connected with the air-pipe that 

 permeates each division of the sucker. 



It will not be a very violent transi- 

 tion if from the sucking pump of the 

 Butterfly I carry you to the silk- spin- 

 ner of the caterpillar. Here I have a 

 Silkworm in the act of commencing 

 its cocoon ; by enclosing which in this 

 glass tube we shall conveniently have 

 the insect at command, and shall be 

 able to view the process under a low cylinder, 



magnifying power and reflected light. Now the gray face 

 of the worm is presented to us; and we can see, below the 

 edge of the head-shield, a short broad upper lip, forming 

 two blunt points. Below this is the pair of strong brown 

 mandibles, convex outwardly and concave inwardly, each 

 cut at its broad biting edge into several teeth. Below 

 these are two little points which represent the maxillce, 

 and between them a blunt rounded knob, which is the 

 lower lip (labium). 



