Page:Jardine Naturalist's library Entomology.djvu/139

Rh bags appended to its surface in certain tribes. They produce the appearance of a coarse villosity, (Pl. II. fig. 2d,) but when examined with the microscope, they are found to be little bags, opening into the ventricle. They are formed by the internal mucous membrane, the other membranes not entering into their composition. The greatest diversity of opinion prevailed among physiologists respecting the functional uses of these appendages, but it seems now to be the most generally received opinion that they are secerning organs, and that their secretions act as solvents on the contents of the ventricle, particularly when these consist of animal matter, for it is among the cranivora that they are principally found. Other appendages sometimes occur characteristic of particular races. The remaining portion of the nutrimental canal may be called the intestine. It is always more simple in form, considerably narrower, and more delicately constructed than the preceding divisions. The slight expansions and contractions which it offers in certain parts of its course, have led some to regard it as consisting of nearly the same portions as the intestines of the vertebrata, and they consequently recognise a duodenum, an ilium, a cæcum, a colon, and a rectum. If we were perfectly acquainted with the functions of these organs in insects, as has been judiciously remarked, it is possible that we might find reason for these numerous divisions, each having a special function alloted to it; but in our present uncertainty in this respect, we run less risk of error by