THE DIGESTIVE SYSTEM 79 



When a considerable amount of water is drunk most of it passes 

 at once into the small intestine. 



When horses are fed different kinds of foods in succession, it 

 has been found, by killing them at varying intervals after feeding, 

 that the first food taken passes into the most ventral part of the 

 stomach. Subsequently, ingested food is arranged in layers, pro- 

 vided its consistency is sufficient to hold it from forming a mechan- 

 ical mixture with previously ingested materials (Fig. 23). 



There is some difference of opinion in regard to the effect of 

 watering a horse after feeding. It is evident that when a horse 

 which has eaten an ordinary feed drinks any great quantity of 



Pijlorus 



Fig. 23. — Longitudinal section of stomach and contents to show how 

 food is distributed in the stomach. The horse was fed, in turn, (1) 500 grams 

 hay; (2) 750 grams uncolored oats; (3) 750 grams colored oats; (4) 500 grams 

 hay. 



water, both cannot be accommodated in the stomach. Scheunert 

 and Schattke^ conclude, from a series of experiments which they 

 carried out: (1) That the drinking of water in any amount desired 

 by the animal exerted no deleterious effect on digestion. (2) 

 That the increase in the water content of the ingesta was inconsid- 

 erable, reaching at most 10 per cent, above the normal average; a 

 similar increase can be produced by the large amount of saliva 

 secreted during mastication of hay or by exercise. The interval 

 before return to the usual lower water content varies individually; 

 in one case it was only ten minutes in duration, but in general 

 appears to be one or two hours. (3) The bulk of the water leaves 



1 Cited by Sisson. 



