344 VETERINARY PHYSIOLOGY 



In the large intestine the caecum and double colon 

 perform much the same function as the oesophageal diverticula 

 of the ruminant (p. 339). 



The Caecum acts as a reservoir. The contents of the small 

 intestine pass through it to reach the colon. Water drunk 

 passes very rapidly to the ceecum. The contents are always 

 fluid, varying from a pea-soup-like consistency to a quite 

 watery liquid, with particles of undissolved food floating 

 throughout it. Some of the food may remain for as long as 

 twenty-four hours in the caecum. On the other hand, some 

 may pass rapidly through to the colon. Food has been 

 found in the colon four hours after being eaten. 



The outlet to the colon is above the level of the inlet — 

 the ileo-csecal valve. The contents therefore are emptied 

 against gravity by the contraction of the four longitudinal 

 muscular bands in the walls of the orsfan. 



The contents of the large colon and of the first foot or 

 so of the small colon resemble those of the ccecum. There- 

 after by the absorption of water the contents rapidly become 

 inspissated, and by the sacculation of the colon, formed into 

 balls of fseces, ready for expulsion. 



The digestive change that takes place in the ca3cum and 

 large colon are much the same as those that occur in the 

 rumen of the ox. The contents are alkaline in reaction and 

 swarm with bacteria. Fibrous material that has resisted the 

 action of the stomach and small intestine becomes macerated. 

 Cellulose is attacked by bacteria and broken down, yielding 

 the same products as the disintegration of cellulose in the 

 rumen (p. 340). The gases appear as little bubbles scattered 

 throughout the fermenting mass. 



As the cellulose envelope is broken down, the contents 

 that were protected from the action of the digestive secretion 

 of the stomach and small intestine are hydrolysed by the 

 enzymes that have been carried into the large intestine. 



Proteins that have not been hydrolysed by the digestive 

 enzymes are disintegrated by putrefactive organisms giving 

 rise to a series of aromatic bodies (p. 329), which are absorbed. 

 Some of these are toxic and affect the health of the animal. 



Absorption of the products of digestion takes place in the 



