DIGESTION 



231 



carbonic acid, leguminous matters producing sulphuretted 

 hydrogen and hydrogen. 



For Intestinal Absorption, see p. 283. 



The Faeces. — The faeces consist of that portion of the food 

 which is indigestible, together with that part which, though 

 digestible, has escaped absorption ; mixed with these are water, 

 colouring substances, mucin, organic matters in great variety, 

 inorganic salts, bile pigment, volatile fatty acids, remains of 

 digestive fluids, organisms, etc. 



The composition of the faeces depends largely on the diet. 

 The following table from Gamgee* is only intended to give a 

 general idea of their nature : 



Approximate Composition of the F^ces of the 

 Horse, Cow, Sheep, and Pig. 



Considerable differences exist amongst animals in the con- 

 sistency of the faeces ; they are moderately firm in the horse, 

 pultaceous in the ox, and hard in the sheep. These differences 

 depend upon the amount of fluid they contain. In the pig they 

 are human-like and very offensive ; in the dog they are soft or 

 hard, dark or light, depending on the diet, the mineral matter of 

 bones producing the light-coloured excreta. It is necessary to 

 remember that the proportion of fluid in the faeces does not depend 

 upon the amount of water which is drunk, but rather on the 

 character of the food, the activity of intestinal peristalsis, and 

 the energy with which absorption is carried on in the digestive 

 canal. Succulent green food in horses produces a liquid or 

 pultaceous motion ; other foods, such as hay and chaff, have a 

 constipating effect, the faeces being large and firm ; excess of 

 nitrogenous matter in the food produces extreme fcetor of the 

 dejecta, and frequently diarrhoea, probably due to putrefactive 

 processes. Nervous excitement frequently induces a free action 

 of the bowels, accompanied by liquid faeces. 



* ' Our Domestic Animals in Health and Disease,' p. 253. 



