346 NATURAL THEOLOGY. 



nished with mouths are such,) when the purpose 

 could be better answered by the deviation. 



In some insects the proboscis, or tongue, or 

 trunk, is shut up in a sharp-pointed sheath, which 

 sheath,^' being of a much firmer texture than the 

 proboscis itself, as well as sharpened at the pomt, 

 pierces the substance which contains the food, and 

 then operis within the wound, to allow the inclosed 

 tube, through which the juice is extracted, to per- 

 form its office. Can any mechanism be plainer 

 than this is, or surpass this ? 



V. The metamorphosis of insects from grubs 

 into moths and flies is an astonishing process. A 

 hairy caterpillar is transformed into a butterfly. 

 Observe the change. We have four beautiful wings 

 where there were none before — a tubular pro- 

 boscis in the place of a mouth with jaws and teeth,^^ 



^' The mouth of the common flea {Pulex irritans) is of this na- 

 ture; it is (o nposed of seven pieces, a pair of mawlibles, a pair 

 of maxillce, two palpi or feelers, and a tongue. The uses of these 

 pieces appear to be as follows : — -the mandibles, which are short, 

 gtroncr, and sharp, are to cut through the outer skin ; the maxillce, 

 which are long and shaped like lancets, are to pierce still deeper 

 so as to cause bleeding : the tongue is then used to lick and con- 

 vey the blood *o the oesophagus; and the palpi are to direct these 

 operations, conveying information to the animal by feeling or touch. 

 These same seven parts (forming the mouth, and technically call- 

 ed trophi) are to be found in almost all insects, but constructed in 

 different ways to suit the various habits of the species. 



"* The mouth of the cat.>rpillar, or larva state of insects, has, 

 in the greater portion of the species, the same number of parts a? 

 that of the perfect insect. In the pupa state some of th^se parts 

 become nearly or quite obliterated, whilst others are much more 

 developed to suit the habits of the animal in its next or perfect 



