158 THE VITAL FUNCTIONS. 



is that of tlic caterpillar; the second, that of the chrysalis; 

 and the third, that of the moth. The whole canal and its 

 appendages, have been separated from their attachments, and 

 spread out so as to display all their parts; and they are de- 

 lineated of the natural size, and in each case, so as to show 

 their comparative dimensions in these three states. In all 

 the figures, A is the oesophagus; b, the stomach; c, the small 

 intestine; d, the ccecal portion of the canal; and e, the colon, 

 or large intestine. The hepatic vessels are shown at f; and 

 the gizzard, which is developed only in the moth, at g, Fig. 

 328. 



It will be seen that in the caterpillar, (Fig. 326,) the sto- 

 mach forms by far the most considerable portion of the ali- 

 mentary tube, and that it bears some resemblance in its struc- 

 ture and capacity to the stomachs of the Annelida, already 

 described.* This is followed by a large, but short, and per- 

 fectly straight intestine. These organs in the pupa (Fig. 

 327) have undcgone considerable modifications, the whole 

 canal, but more especially the stomach, being contracted both 

 in length and width if the shortening of the intestine not 

 being in proportion to that of the whole body, obliges it to 

 be folded upon itself for a certain extent. In the moth, 

 Fig. 328,) the contraction of the stomach has proceeded 

 much farther; and an additional cavity, which may be consi- 

 dered as a species of crop or gizzard (g,) is developed: the 

 small intestine takes a great many turns during its course, 

 and a large pouch, or cxcum, has been formed at the part 

 where it joins the large intestine. 



The hepatic vessels are exceedingly numerous in the Crus- 

 tacea, occupying a very large space in the general cavity; 

 and they compose by their union an organ of considerable 

 size, which may be regarded as analogous in its functions to 



• Sec the figures and description of those of the Nais and the Leech, p. 



102 and 103. 



f Cams states tliat he found tlie stomach of a pupa, twelve days after it 

 had assumed that state, scarcely half as long, and only one-sixth as wide as 

 it had been in the caterpillar. 



