THE DIGESTION OF FOOD 95 



partially or wholly performed for the animal in hay- 

 cutters and grain mills. This mastication is essential for 

 two reasons: (1) It puts the food in condition to be swal- 

 lowed, and (2) fits it for the prompt and efficient action 

 of the several digestive fluids. Dry whole hay or kernels 

 of grain could hardly be forced down the tube leading to 

 the animal's stomach. It is necessary for these mate- 

 rials to be broken down and moistened in order that they 

 may be swallowed. Even if they could be conveyed to the 

 stomach in their natural condition the process of render- 

 ing their constituents soluble would proceed very slowly. 

 The more finely any solid is ground, the larger is the sur- 

 face exposed to the attack of the dissolving liquid and 

 the more rapid the action. 



132. The teeth. Prompt and rapid solution of food 

 is essential, because, if it is too long delayed, uncomforta- 

 ble and injurious fermentations are likely to set in, and, 

 because of imperfect digestion, the final nutritive effect 

 of the ration may be diminished. For these reasons, 

 animals with diseased teeth, or those that have lost teeth, 

 make poor use of their food, and require an unnecessary 

 amount to keep them in condition. These conditions 

 may often be a cause, especially with horses, of disappoint- 

 ing results from an ordinarily sufficient ration. The teeth 

 of our domestic animals differ somewhat in number and 

 arrangement. Authorities state the following to be the 

 usual number: 



TABLE XXV 



Total Incisors Canines Molars 



Horse 36-40 12 4 24 



Ox 32 8 24 



Sheep and goat 32 8 24 



Pig 44 12 4 28 



