156 THE VITAL FUNCTIONS. 



coats of which the longitudinal muscular bands are very dis- 

 tinctly seen. Fig. 322 is a magnified view of the gizzard 

 laid open, to show its internal structure. It is furnished 

 with six longitudinal rows of large teeth, and six intermedi- 

 ate double rows of smaller teeth; the total number of teeth 

 being 270. One of the rows of large teeth is seen, detached, 

 and still more magnified, in Fig. 323; it contains at the up- 

 per part, five small hooked teeth (f,) succeeded below by 

 four broad teeth (d,) consisting of quadrangular plates, and 

 twelve tricuspid teeth (t;) that is, teeth having three cusps, 

 or points at their edges. Fig. 324 shows the profile of one 

 of these teeth; a, being the sharp point by which the ante- 

 rior acute angle of the base terminates. Fig. 325 exhibits 

 the base of the same tooth seen from below, e, e, e, being 

 the three cusps, and m, the triangular hollow space for the 

 insertion of the muscles which move them, and which com- 

 pose part of the muscular apparatus of the gizzard. The 

 smaller teeth, which are set in double lines between each 

 of the larger rows, consist of twelve small triangular teeth 

 in each row. All the teeth contained in this organ are of a 

 brown colour and horny texture, resembling tortoise shell. 

 The same insect, as we have seen, often exhibits, at dif- 

 ferent periods of its existence, the greatest contrast, not only 

 in external form, but also in its habits, instincts, and modes 

 of subsistence. The larva is generally remarkable for its 

 voracity, requiring large supplies of food to furnish the m,a- 

 terials for its rapid growth, and frequently consuming enor- 

 mous quantities of fibrous vegetable aliment: the perfect in- 

 sect, on the other hand, having attained its full dimensions, 

 is sufliciently supported by small quantities of a more nu- 

 tritious food, consisting cither of animal juices, ^r of the 

 fluids prepared by flowers, which are generally of a saccha- 

 rme quality, and contain nourishment in a concentrated 

 form. It is evident that the same apparatus, which is ne- 

 cessary for the digestion of the bulky food taken in during 

 the former period, would not be suited to the assimilation of 

 that which is received during the latter; and that in order 



