316 ZOOLOGY.. 
The intestine (ileum) lies in the fifth and sixth a dominal 
segments. : 
Behind the intestine is the colon, which is smaller than 
the intestine proper, and makes a partial twist. The colon 
suddenly expands into the rectum, with six large rectal 
glands on the inside, held in place by six muscular bands 
attached anteriorly to the hinder end of the colon. The 
rectum turns up toward its end, and the vent is situated 
just below the supra-anal plate. 
Having described the digestive canal of the locust, we 
may state in a summary way the functions of the different 
divisions of the tract. The 
food after being cut up by the 
jaws is acted upon while in 
the crop by the salivary fluid, 
4a Which is alkaline, and pos- 
: Gi) sesses the property, as in ver- 
\ Jl tebrates, of rapidly transform- 
} ing the starchy elements of 
the food into soluble and as- 
similable glucose. The diges- 
tive action carried on in the 
crop (ingluvies) then, in a veg- 
= ; etable-feeding insect like the 
Fig 277.—Transverse section of the locust, results in the conver- 
Sinkoular walls; ‘r-horny nidge between Sion of the starchy matters 
the large teeth.—After Minot. into glucose or sugar. This 
process goes on very slowly. When digestion in the crop 
has ended, the matters submitted to an energetic pressure 
by the walls of the crop, which make peristaltic contrac- 
tions, filter gradually through the short, small proventricu- 
lus, directed by the furrows and chitinous projections lining 
it. The apparatus of teeth does not triturate the food, 
which has been sufficiently comminuted by the jaws. This 
is proved by the fact, says Plateau, that the parcels of food 
are of the same form and size as those in the crop, before 
passing through the proventriculus. The six large lateral 
pouches (coeca) emptying into the commencement of the 
stomach (ventriculus) are true glands, which secrete an al- 
