ANIMAL STRUCTURE AND FUNCTION. 1 5 



opposed to the much more solid contents of the rest of the large bowel ; 

 and in addition to taking its part in digestion it appears to be a reservoir 

 where water is stored and from whence it is issued to the body as required. 

 The remaining portion of the large bowel {the colo?i) is doubled twice on 

 itself the entire length of the belly and ends in the rectum. It is in the 

 last part of the colon that the animal's droppings take their characteristic 

 shape before expulsion. The unabsorbed portions of the food pass very 

 slowly along the large bowel, being continually kneaded by the constant 

 worm-like motions of the gut until all the nutriment which the animal is 

 capable of extracting from it has been absorbed. 



The main actions of the various digestive fluids are as follows : — Actions ot 



The saliva, by its viscidity and quantity, renders swallowing easy and digestive 

 also helps to convert the starches of the food into sugar, which is a fluids, 

 necessary preliminary to their absorption. 



The gastric juice, which is acid, converts the flesh-forming (proteid) 

 portions into more easily absorbed substances known as " peptones," 

 assists in breaking up the fibrous portions and converts starches into 

 sugars. 



The exact role of the secretions of the bowels themselves are not 

 thoroughly ascertained, but in the large bowel especially the digestion 

 of fibrous materials is mainly carried on. 



The bile converts fats into an emulsion and acts as a disinfectant of 

 the general contents of the bowels. 



The pancreatic juice may be termed a general digestive fluid ; it 

 further converts starches into sugar, turns flesh-formers (proteids) into 

 peptones and emulsifies fats. 



After undergoing these changes a large portion of the nutrim.ent is 

 absorbed, sucked up, by the inner coats of the bowel and poured into 

 the lymphatics of the bowel or the blood-vessels which run from the 

 bowels and stomach to the liver, where, as before mentioned, it is 

 suitably prepared as fuel for the use of the muscles and either issued 

 or stored up as required. Owing to this a temporary congestion of the 

 liver occurs after feeding, and if the organ is not assisted in its functions 

 by judicious exercise it is liable to get out of order. 



In the foregoing account the digestive organs of the horse have been 

 described, but there are some differences between them and the organs 

 of ruminants, e.g., the ox and camel, which require note. 



The digestive system of riwiinaitts generally is designed to cope with The 

 a rough and bulky class of forage and provides for its mastication twice digestive 

 over. The molar teeth are more jagged to grind coarse food ; the tongue system of 

 is harder, to guard against injury ; and the gullet is more capacious, and ruminants. 



