142 ANATOMY AND PHYSIOLOGY 



stages of development. The striking changes in 

 outward appearance implied by the terms complete 

 metamorphosis, prepare us to expect some corre- 

 sponding alteration in internal organs, and this, ac- 

 cordingly is found to he the case. The proportions 

 of the different parts are not only different, but 

 some of the parts found in the perfect insect are 

 wanting in the larva, while others exist which dis- 

 appear in the final stage. Such changes are indis- 

 pensable when the larva lives on one kind of food, 

 and the imago on another, (as in the Lepidoptera, 

 for example,) but they likewise occur in cases when 

 the food is the same in both conditions. In the larva 

 of the carnivorous Coleoptera, for instance, which are 

 equally predaceous with the mature insect, the only 

 distinguishable parts of the alimentary canal are the 

 esophagus, a minute crop, a chylific ventricle, and 

 a small gut the ventricle being perfectly smooth 

 externally. To what an extent this differs from the 

 canal of the imago, will appear from a comparison 

 with that of the common Tiger-beetle (C. campestris), 

 formerly described, and figured on Plate 1st, fig. 2. 

 Many instances of it being comparatively short in the 

 early stages, are to be found in the same order, but 

 in none is this more notable than among the phy- 

 tophagous Lamellicorn beetles. That of the larva 

 scarcely exceeds the length of the body, all the sub- 

 ordinate parts being absorbed (so to speak) by a 

 capacious stomach filling nearly the whole of the 

 splachnic cavity. This expansive ventricle, after the 

 last metamorphosis, becomes narrow, its component 



