DIGESTIVE SYSTEM. 329 
greater suriace, and aid the action of the lacteals, the inner 
coat of the intestine is villous, and likewise covered with 
various rugse, which have been termed valvulae conniven- 
tes. The villi possess a vascular structure, and, when 
destitute of chyle, have been compared to little loose pen- 
dulous bags. It is this villous coat, which, when there is 
a separation of the intestines into large and small, character- 
ise the latter. In the duodenum and jejunum, the chyme 
acquires the nature of chyle, and in the ilium the separation 
is completely effected between it and the faeces. These last 
consist of the useless part of the food, coloured by the union 
of a part of the bile, which is never reabsorbed. When the 
lacteals have finished the absorbing process, the faeces now 
leave the portion of the intestine destined for digestion, and 
enter the larger intestines, which are storehouses, in which 
_ the useless part of the food is placed until it can be conve- 
niently evacuated. The larger intestines are characterised 
by their superior dimensions and strength, but more par- 
ticularly by the absence of the villous coat. 
The larger intestines are divided into three parts, the 
coecum, colon, and rectum. The upper extremity of the 
colon is closed, and as the ilium enters laterally and _a little 
way from the end, the head of the colon consequently 
forms a blind gut or cecum. Sometimes there is attached 
to this caput coecum coli, another tubular appendage closed 
at its free extremity, termed appendia vermiformis. The 
orifice of the ilium where it enters the colon is furnished 
with folds, which probably regulate the quantity of matter 
discharged into the colon, and prevent regurgitation. 
These folds constitute what is termed valvula coli. When 
the feces have undergone all the changes which are neces- 
sary in the colon, and traversed its tortuous cavity, they 
enter a portion of the intestine, which, from the straight- 
ness of its course, is termed the reclwm, which opens ex- 
ternally by the anus. 
