1 84 A MANUAL OF VETERINARY PHYSIOLOGY 



horse and man a considerable amount has been written to prove 

 that the acidity depends upon lactic or hydrochloric acids, and 

 it is possible that both these views may be reconciled. Ellen- 

 berger and Hofmeister are of opinion that shortly after a meal 

 lactic acid predominates in the horse's stomach, to be replaced 

 by hydrochloric acid some four or five hours after the commence- 

 ment of feeding. These observers found that the nature of the 

 acid depended upon the region of the stomach, the period of 

 digestion, and the character of the food ; oats induced an out- 

 pouring of hydrochloric acid, whilst hay favoured the organic acids. 



The following are Ellenberger's views on the nature of the 

 stomach acids : 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 predominates, 

 0*25 per cent., and lactic acid is found, in small quantities. In 

 vegetable feeders lactic acid at first predominates, 0-4 per cent., 

 and later HC1 is present 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 a long digestion hydrochloric 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. 



It has been suggested that the presence of lactic acid in the 

 stomach of herbivora may be due to the fermentation of the 

 carbohydrates of the food, and this cannot be doubted as a con- 

 tributory cause. In the dog, in which animal the acid is doubt- 

 less hydrochloric, it is well known that no free HC1 may be 

 obtained for the first hour or two of digestion, owing to the acid 

 combining with the protein of the food, and the diminution it 

 undergoes in neutralising the alkali of the saliva. 



The writer's experience regarding the presence of hydrochloric 

 acid and organic acids in the stomach contents is that, no matter 

 at what period of digestion observations have been made, on 

 only two or three occasions has he succeeded in finding hydro- 

 chloric acid in the stomach of the horse, and he is convinced that 

 lactic is the chief, if not the sole, digestive acid in this animal. 



The Secretion of Gastric Juice is accomplished in certain 

 glands known as the gastric. In man these are divided into 

 cardiac and pyloric, each having not only a different structure, 

 but a separate function. In the horse cardiac glands are impos- 

 sible owing to the presence of the cuticular coat ; but it has been 

 shown that the villous coat contains glands corresponding to 

 cardiac, which are principally situated in the greater curvature, 

 at the fundus of the stomach, and extending over a limited area, 

 described on p. 174 as not larger than one square foot (Fig. 62). 



