312 DIGESTION. 



in which gastric fistulse had been formed, and partly to animals 

 that were killed (generally with a view to other investigations) at 

 definite times after taking food, are limited to the following facts, 

 which increase rather than diminish the uncertainty of our 

 knowledge. 



As in the first place we shall only consider the retention of food 

 in the stomach, we shall commence with the digestibility of the 

 albuminous substances. 



With regard to soluble coagulable albumen, it has been already 

 mentioned (see vol. ii, p. 54) that, according to my experience, 

 this substance undergoes a change in the stomach, and is not 

 resorbed unchanged, as Frerichs maintains. Blondlot saw the 

 white of 4 eggs entirely disappear from the stomach in the course 

 of 2| hours. We can here very distinctly observe the influence 

 which the quantity exerts on the relative digestibility of the food ; 

 if we introduce the w T hite of one egg into the stomach of a dog with 

 a gastric fistula, but otherwise healthy, after it has fasted for about 

 12 hours, we often find in the course of an hour no remaining trace 

 of coagulable matter ; but we are more certain to find such traces 

 when the white of two eggs has been taken. If the white of eight 

 or more eggs was given to the same dog, which was one of average 

 size, weighing about 5 kilogrammes [or 11 Ibs.], coagulable matters 

 could always be recognised in the stomach after 3 or even after 4 

 hours, except in cases in which the dog had vomited a portion of 

 the substance. 



Densely coagulated blood-fibrin requires a longer period for 

 gastric solution than the same substance in a finely comminuted 

 state; a fasting dog swallowed 9*5 grammes of the moist fibrinous 

 crust (buffy-coat) obtained from coagulated horses' blood, and 

 after 2| hours fragments of it were still contained in the stomach ; 

 the same quantity of blood-fibrin obtained from the red coagulum 

 of horses' blood disappeared, with the exception of a few flakes, 

 from the stomach of the dog in the course of 11 hours. It 

 might have been expected from the simplest chemical experi- 

 ments, that the degree of cohesion would essentially influence the 

 more or less easy digestion of a substance, and this view is 

 thoroughly bore out by further direct investigations. Fluid, finely 

 divided, porous foods are much more open to the action of the 

 digestive juices, and must necessarily be more readily digestible 

 than others which do not possess these properties in an equal 

 degree. 



In order to determine the digestibility of coagulated albumen, we 



