ITT 



THE DTGESTIVE ORGANS 



39 



The duration of digestion of hay by the stoniach lias been 

 worked out experimentally by Colin and l)}^ Smith. Colin found 

 that the rate of digestion during the first two hours is rapid, but 

 that it afterwards decreases so that at the end of eight hours 

 some hay is still retained in the stomach. Smith starved a horse 

 for twenty-four hours and then gave it 6 lbs. of dried grass; 

 the horse was destroyed nine hours afterwards when the stomach 

 contained 2h lbs. showing that 3i lbs. had been digested. Other 

 experiments illustrated the same jioint, namel}^ the iricreasingly 

 slow rate of digestion the longer the time that had elapsed after 

 a meal. 



In digesting oats the same fact was observed. Smith found 

 that in a horse which had received 2 lbs. and was killed twenty 

 hours later the stomach was not empty. 



Fig. 24. Section through stomach of horse showing syphon-trap 

 of duodenum {duo), u' oesophagus, py. pylorus, d left sac, and 

 r fundus. (From Smith, Messrs Bailliere, Tindall and Cox.) 



If a horse be fed with different foods in succession these 

 arrange themselves in the stomach in the order in which they 

 enter, and pass out in the same order without mixing unless the 

 horse is watered after its meal. The effect of watering is to 

 disturb the arrangement of the food and to wash a large part of 

 it, in a very undigested state, into the small and large intestine 

 where it may produce irritation and colic. Hence, the importance 

 of watering a horse before feeding and not afterwards. 



The acids which are present in the digesting stomach depend 

 partly upon the nature of the food. It has been said that 

 hay induces an outpouring of lactic acid and oats of hydro- 



