66 RELATIVE DIGESTIBILITY OF FOOD. 



resenting soluble albumen, if introduced into the stomach of a fasting dog 

 through a gastric fistula, will disappear in less than an hour ; but if the 

 whites of eight eggs be introduced, portions thereof can be recognized 

 after four hours. Lehmann, who made these observations, adds that 

 blood fibrin varies in its time for gastric solution according as it is in a 

 finely comminuted or a massive state ; in the former instance disappear- 

 ing from the stomach of a dog in an hour and a half, but the same weight 

 in the latter condition requiring almost twice the time. Coagulated al- 

 bumen indicates the commencement of digestion, and even its local com- 

 pletion, in from five minutes to a quarter of an hour ; but here again much 

 depends on the condition of the stomach and the general state of the sys- 

 tem, whether the animal has been fasting, and whether the gastric juice 

 is exuding in a dilute or concentrated state. 



So far as such examinations go, they do not exhibit any marked dif- 

 Kespiratory di- ference between albumen, fibrin, and casein. Gelatine, how- 

 gestion, as of ever> { s acted on with remarkable rapidity. Beaumont ob- 

 gln in the served that in an hour 150 grammes of jelly had disappeared, 

 stomach. The, experiments which have been made on the digestibility 



of vegetable food introduced through gastric fistula? are obviously of no 

 use, since the chief constituents thereof, such as starch and fat, are not 

 even influenced in those circumstances until they have reached the intes- 

 tine. Their passage from the stomach in this unchanged state, or 

 changed only so far as their nitrogenized ingredients are concerned, may 

 teach us the important fact, which should in these inquiries be always 

 borne in mind, that disappearance from the stomach is one thing and di- 

 gestion another, and that even though a substance may have passed the 

 pyloric valve, its digestion, far from having been completed, may not as 

 yet have commenced. 



The digestion of nutritive or nitrogenized material histogenetic diges- 

 tion is therefore carried on in the stomach mainly ; and though first 

 mechanical, and then chemical agencies are resorted to, the object is 

 throughout the same to obtain the food in such a divided and changed 

 state that it can pass, dissolved in water, into the capillary vessels. 



