DIGESTION.) PHYSIOLOGY. I2i 



And water passes into the blood everywhere along 

 the whole length of the canal. 



When we eat a piece of bread, while we are chew- 

 ing it in our mouth it is getting moistened and mixed 

 with saliva. Part of its starch is thereby changed 

 into sugar, and all of it is softened and loosened. 

 Passing into the stomach, some of the proteids are 

 dissolved out by the gastric juice, and pass into the 

 blood, and all the rest of the bread breaks up into 

 a pulpy mass. Passing then into the intestine, what 

 is left of the starch is changed by the pancreatic 

 juice into sugar, and is at once drained off either 

 into the lacteals or straight into the blood. Iti 

 the intestine what remains of the proteids is dis- 

 solved, till nothing is left but the shells of the tiny 

 chambers in which the starch and proteids were stored 

 up by the wheat-plant as it grew. 



When we eat a piece of meat, it is torn into mor- 

 sels by the teeth and well moistened by saliva, but 

 suffers else little change in the mouth. In the stomach, 

 however, the proteids rapidly vanish under the action 

 of the gastric juice. The morsels soften, the fibres 

 of the muscle break short off and come asunder ; 

 the fat is set free from the chambers in which it was 

 stored up by the living ox or sheep, and, melted by 

 the warmth of the stomach, floats in great drops on 

 the top of the softened pulpy mass of the half-digested 

 food. Rolled about in the stomach for some time 

 by the contraction of the muscles which help to form 

 the stomach walls, losing much of its proteids all the 

 while to the hungry blood, the much-changed meat 

 is siqueezed into the intestine. Here the bile and 

 the pancreatic juice, breaking up the fat into tiny 



