Digestion. 121 



When the stomach is empty, as after a few days' starva- 

 tion, its reaction is neutral or alkaline. I have observed 

 extreme alkalinity towards the pylorus under these con- 

 ditions, due no doubt to the regurgitation of bile and 

 pancreatic fluid. 



The Stomach Acids. — It is not necessary here to enter into 

 a long discussion on the nature of the gastric acids. Both 

 in the horse and man a considerable amount has been 

 written to prove that the acidity depended upon lactic or 

 hydrochloric acids. It is possible that both these views 

 may be reconciled. Ellenberger and Hofmeister are of 

 opinion that immediately after a meal lactic acid predomi- 

 nates in the horse's stomach, to be replaced by hydrochloric 

 at about four or five hours from the commencement of 

 feeding. These observers found that the nature of the acid 

 depends upon the region of the stomach, the period of 

 digestion, and the nature of the food, oats inducing an 

 outpouring of hydrochloric acid, whilst hay favoured the 

 organic acids, as seen in the following table : 



On a diet of chopped straw and oats 

 On a diet of oats 

 On a diet of hay 



In the contents of the stomach, hydrochloric, lactic, 

 butyric and acetic acids may be found, the two latter in 

 insignificant quantities only. In flesh feeders HC1 pre- 

 dominates 25 per 1,000, and lactic, in small quantities, 

 •07 per 1,000. In grain feeders lactic acid at first pre- 

 dominates, and later HC1 in small quantities. Lactic acid 

 exists throughout the whole stomach, but predominates in 

 the right and left sacs, whilst hydrochloric acid principally 

 exists in the fundus region. Lactic is the first digestive 

 acid employed, but towards the end of digestion hydro- 

 chloric exists throughout the whole stomach. The amount 

 of lactic acid found in the stomach of the horse during the 

 first hours of digestion is considerable, amounting to If ozs. 

 or even as much as 31 ozs. (Ellenberger;. 



