366 PHYSIOLOGY OF THE DOMESTIC ANIMALS. 



few days previous to the experiment fed on such food as could be readily 

 recognized in the intestinal tube. For thirty-six hours before the exper- 

 iment no food whatever was given. The animals were then killed, after 

 the administration of a weighed quantity of food, at one, two, three, 

 four, six, eight, ten, and twelve hours after the termination of the meal, 

 an attempt being made to isolate the portions obtained from the dif- 

 ferent parts of the stomach, the cardiac and pyloric halves being kept 

 separate. The result of these experiments directed attention especially 

 to the progress of digestion, to the location of the gastric contents, the 

 nature of the acid and quantity of the ferment present, the duration 

 of gastric digestion, the source of gastric juice, and the character of the 

 gastric movements. Their experiments teach that the gastric digestion 

 of grains in the hog may be divided into two periods. During the 

 meal and for one or two hours afterward, digestion of starch alone takes 

 place, the starch being converted into soluble starch, dextrin, and sugar. 

 Simultaneously with the digestion of the starch, lactic acid fermentation 

 occurs, a considerable quantity of the sugar being in this way converted 

 into lactic acid. It does not appear from their results as to whether 

 cellulose, also, at the same time undergoes fermentation or not. During 

 this period the food becomes softened and swollen from maceration in 

 the fluids, and a great part of the soluble matters of the food pass into 

 solution, the digestibility of the vegetable albuminates being facilitated 

 b}' the presence of lactic acid. 



The conversion of the starch into sugar occurring in this period 

 is due to the saliva, which the authors have found in the hog to pos- 

 sess amylolytic power in a high degree. It is strongly alkaline, and 

 therefore neutralizes whatever acid was first present in the stomach. 

 Later, the cardiac contents become acid, due at first to the presence of 

 lactic acid, which, as is well known, does not interfere with the action of 

 the amylolytic ferment. It is also probable that a certain amount of this 

 amylotytic ferment comes from the cardiac sac of the .hog's stomach, 

 which, as already mentioned, contains a special character of glands 

 whose extract always yields diastatic ferments. 



As regards the degree of digestion in this period, the following 

 figures, taken from one of Ellenberger's and Hofmeister's experiments, 

 serve as an example : 



The animal had received 860 grammes of oats, representing 73 

 grammes of cellulose, 557 grammes of carbohydrates, and 93 grammes 

 of albuminoids. As a consequence, 22.5 per cent, soluble nutritive sub- 

 stances consisted of albumen. On analysis, only 47 grammes of undis- 

 solved albumen were found ; hence 34 per cent, of the insoluble albuminous 

 bodies had passed into solution. 



In feeding with animal matters, naturally this first stage, which 



