478 THE DIGESTIVE APPARATUS IN MAMMALIA. 



Dimensions — Capacity. — Its length is ordinarily a little over three feet, and it 

 will contain, on an average, about 7^ gallons of fluid. 



Form — External surface. — The elongated sac formed by the caecum is conical 

 in shape, terminating in a point inferiorly, and bulging and curved like a crook 

 superiorly. Externally, it exhibits a great number of circular furrows, inteiTupted 

 by longitudinal muscular bands, four of which are observed in the middle portion 

 of the organ ; they disappear towards its extremities. The bottom of these 

 furrows necessarily corresponds to the internal ridges, and these can be made to 

 disappear by destroying the longitudinal bands, which considerably lengthens the 

 CEecum ; thus showing that these transverse puckerings are due to the presence of 

 the riband-like cords, and have for their object the shortening of the intestine 

 without diminishing the extent of its surface. 



ReJatmis. — To study its relations, the caecum is divided into three regions : — 



1. The superior extremity, base, arch, or still better, the crook, shows in the 

 concavity of its curvature, wMch is turned forwards, the insertion of the small 

 intestine and origin of the colon. Placed in the sublumbar region, it is related, 

 superiorly, to the right kidney and the pancreas, through the medium of an 

 abundant supply of connective tissue. Outwardly, it touches the parietes of the 

 right flank, and is encircled by the duodenum. On the inner side, it adheres by 

 connective tissue to the termination of the large colon, and is in contact with the 

 convolutions of the small intestine. 



2. The middle portion is in contact, inwardly, with the same convolutions and 

 the large colon ; outwardly, with the cartilages of the false ribs, in following their 

 cm'vature. 



3. The inferior extremity, or point, usually rests on the abdominal prolongation 

 of the sternum ; but as it is free and can move about in every direction, it often 

 happens that it is displaced from this situation. 



Mode of attachment. — The ctecum is fixed to the sublumbar region and the 

 terminal extremity of the large colon, by a wide adherent surface. All around 

 this surface, the peritoneum — which constitutes the serous covering of the cfecum — 

 is gathered into folds, and in passing from the caecum to the origin of the colon, 

 this membrane forms a particular short and narrow fraenum, designated the 

 meso-ccecum. 



Interior. — Yiewed internally, the caecum offers for study the valvnim, or 

 transverse ridges corresponding to the external furrows. We have already seen 

 that these are due to simple circular folds, comprising in their thickness the 

 three tunics of the organ, and that they can be effaced by distension, to reappear 

 afterwards in varying number and position — differing widely, in this respect, 

 from the valvulce conniventes of the small intestine. 



Two orifices, placed one above the other, open on the internal surface of the 

 caecum, at the point corresponding to the concavity of the crook. The most 

 inferior represents the terminal opening of the small intestine at the centre of 

 the ilio-c cecal valve, the presence of which in the domesticated animals has, in 

 consequence of a wrong appreciation of analogies, been denied ; it is nothing 

 more than the projection described as being made by the terminal portion of the 

 small intestine. The second opening, placed about H or 2 inches above the 

 preceding, and puckered around its margin, establishes a communication between 

 this viscns and the colon. If this opening be compared with the capacity of the 

 canal that begins from it, it will be remarked that it could scarcely be narrower. 



Structure. — The serous tunic does not call for any notice, beyond that 



