GASTEIC DIGESTION. 369 



five kilos of hay, representing one-half its daily ration, requiring two 

 hours for its consumption, and impregnates it with twenty litres of saliva 

 the mass would occupy a space of twenty-eight to thirty cubic decimeters. 

 As the stomach is functionally most active when only two-thirds distended 

 that is, while containing about ten litres, the stomach must, therefore, 

 fill and empty itself two or three times during one meal. It is, therefore 

 seen that the small capacity of the stomach has the effect of reducing the 

 duration of gastric digestion, and the greater the volume of food the 

 less will be the time that food will remain in the stomach. Consequently 

 oats, taking up only one-fifth the volume of an equal weight of hay, 

 would remain in the stomach four or five times as long. This difference 

 in time during which different foods remain in the stomach is necessi- 

 tated, as indicated by Colin, by the different compositions of the food. 

 Thus, a horse fed on hay receives in this food 44 per cent, of carbo- 

 hydrates, which have been already partially modified by the saliva 

 and whose further transformation is completed in the intestine. Four 

 per cent, of fats is present, which, as has been seen, are not acted on by 

 the gastric juice, while only 7 per cent, of albuminous matter is 

 present. It is the albuminous matter alone which is digested by gastric 

 juice, and, since we have only 7 per cent, of albuminous matter pres- 

 ent in hay, it is evident that but a short time, comparatively speaking, 

 would be required for the digestion of this albuminous matter, which is 

 finely divided and in the most favorable condition for being subjected to 

 its solvent action. So, also, the horse fed on green forage receives in 

 its food 9 per cent, of carbohydrates, barely 1 per cent, of fat, and only 

 3 per cent, of nitrogenous matters which are digestible in the stomach. 

 Therefore, in green fodder but a short time is required for gastric diges- 

 tion. On the other hand, oats contain about 11 per cent, of nitrogenous 

 matter, and, consequently, we find that the small relative volume of oats, 

 as contrasted with other forms of vegetable foods, enables them to remain 

 longer in the stomach. 



In the horse the performance of gastric fistulse is impossible on 

 anatomical grounds, and various attempts have been made to collect 

 gastric juice by performing cesophagotomy, — passing a sponge through' 

 a tube into the stomach, killing the animal after a certain time, tying 

 the pylorus, and collecting the contents. This method, however, fails 

 to secure a gastric secretion which is free from bile and pancreatic 

 juice. So, also, the use of the stomach-pump is rendered difficult or 

 impossible on account of the long and pendulous soft palate and the 

 discomforts and struggles which it causes in animals when attempts to 

 employ it are made. 



By means of the method referred to above, the fluids obtained from 

 the stomach will always contain saliva and various food-products, as well 



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