INSECTS: THEIB MOUTHS. 153 



speak) does not perform a complete circle, but only about 

 two-thirds of a circle, leaving a blank space ; and the tips 

 of the wires end alternately in a fine acute point, and in a 

 rounded fork, like the prongs of a pitch-fork. It has been 

 said that these tubes are modified trachea ; but this fact is 

 by no means obvious to me ; for, so far from their being 

 connected with the general tracheal system, each of the 

 four main tubes originates in an open centre, and each 

 has an open extremity. I think it likely that they are so 

 many suctorial pipes, through which the fluid to be drunk 

 is drawn up, entering at their minute open tips, and dis- 

 charging itself into the central cavity by the open basal 

 extremities of the main tubes. 



The most extraordinary modification of jaws, however, 

 is the long spiral tube which is ordinarily coiled up under 

 the face of a Butterfly or Moth, with which it sucks up 

 the sweet nectar of flowers. Many flowers have a deep 

 corolla, and most have the bases of their petals, where 

 the nectar lies, so far from the level of the surface that 

 probing is necessary to reach it. Bees can enter tubular 

 flowers, and lick their bottoms ; and even blossoms that 

 are closed, as the Snapdragon, they know how to force 

 and enter. But Butterflies, with their wide wings, in- 

 capable of being folded, cannot enter flowers bodily, and 

 therefore a peculiar apparatus is given them for stealing 

 their contents, as it were, at the doors. 



Nothing is easier than to examine this beautiful organ 

 with the naked eye ; and much may be learned of its 

 structure by means of a pocket lens. You may thus see 

 in a moment that it forms a flat spiral of several coils, 

 like the mainspring of a watch ; that it runs off to a point, 

 and that this point is double, for it is frequently seen 

 separate a considerable way up. Hence you would pro- 

 bably infer that the organ consists of two equal and similar 

 halves, united lengthwise. And so, indeed, it does ; and 

 these halves are the representatives of the maxilla or 



