OF INSECTS. 
] 33 
bags appended to its surface in certain tribes. They* 
produce the appearance of a coarse villosity, (PI. II. 
fig. 2 d } ) 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 func- 
tional 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 carnivora that they are principally found. Other 
appendages sometimes occur characteristic of par- 
ticular races. 
The remaining portion of the nutrimental canal 
may be called the intestine . It is always more sim- 
ple in form, considerably narrower, and more deli- 
cately constructed than the preceding divisions. The 
slight expansions and contractions whicli it offers in 
certain parts of its course, have led some to regard 
it as consisting of nearly the same portions as the in- 
testines of the vertebrata, and they consequently re- 
cognise a duodenum, an ilium, a ccecum, a colon, and 
a rectum. If we w r ere perfectly acquainted with the 
functions of these organs in insects, as lias been judi- 
ciously remarked, it is possible that w r e might find 
reason for these numerous divisions, each having a 
special function allotted to it ; but in our present un- 
certainty in this respect, we run less risk of error by 
