318 PHYSIOLOGY OF ALIMENTATION. 



and through the action of the teeth is more finely divided. 

 With most individuals the food as it slips into the stomach 

 still contains large masses of undivided food, made up more 

 particularly of pieces of meat and smaller but still coarse 

 pieces of boiled potato, bread, etc. The mechanical action 

 of the stomach, together with the action of the large quanti- 

 ties of gastric juice poured out under physiological condi- 

 tions upon the food in this locality, serves to change even 

 the external appearance of the mixed food. Not only are 

 the larger pieces of starchy food broken into smaller ones 

 through the muscular contractions passing over the stomach, 

 but pieces of swallowed meat suffer similar changes in their 

 state of aggregation. The connective tissue found in them 

 is acted upon by the gastric juice and the cellular elements 

 in consequence are allowed to fall apart. Fatty tissues suffer 

 a similar change, and the fat contained within the cells 

 becomes free. If any fats have been consumed which at 

 ordinary temperatures are solid, but melt at body temper- 

 atures, these melt. The formation of peptones from the 

 protein of the meal imparts to the gastric contents a bitter 

 taste. 



The acid, liquid, partially digested gastric contents pass 

 over in small amounts into the duodenum. Here they have 

 poured out upon them, as soon as they pass the pancreatic 

 duct, the bile and pancreatic juice. The color of the bile im- 

 parts itself to the alimentary contents, and the alkaline reac- 

 tion of the pancreatic juice reduces the acidity of the food as 

 it has escaped from the stomach. Throughout the small in- 

 testine the food exists only as a sticky, mucinous, brownish- 

 yellow mass which adheres more or less closely to the mucous 

 membrane of the alimentary tract. The viscosity of this 

 mass increases gradually from above downward, and no- 

 where throughout the small or large intestine do the alimen- 

 tary contents show to the naked eye any of the character- 

 istics of the food originally consumed by the individual. 

 These are quite effectually lost even in the stomach after 



