142 



DIGESTION 



many instances, led to the habit of taking alcoholic liquors. 

 These two habits do not always co-exist in the same persons, 

 but the danger that the one will lead up to the other is so 

 great that they are frequently spoken of as the " twin vices." 



The young should appreciate this danger, and should also 

 remember that the habit of using tobacco is most commonly 

 established early in life,. if at all; very few persons, compara- 

 tively, who have passed twenty years of age without forming 

 the habit, adopt it in their later years. 



TOPICAL OUTLINE 



THE 



CAVITIES OF 

 THE TRUNK 



Thorax or 

 Chest 



Diaphragm 



Abdomen . 



Shape 



Walls 



f Conical, with the diaphragm 

 1 as its base. 

 f Back Vertebral column. 



{ Ribs. 



I Intercostal muscles. 



Front | Sternum> 



1 Costal cartilages. 



Floor Diaphragm . 

 f A muscular partition, dividing the thorax 

 from the abdomen. Convex above and 

 [ concave below. 



f Roof Diaphragm. 

 Back Vertebral column. 

 Sides and Front Abdomi- 

 nal muscles. 



Walls 



f Solution cojnmenced in the mouth by the 



Starchy foods -I *~ saliva - 



I Completed in the intestines by the intestinal 



I juices. 

 Solution commenced in the stomjach by the 



gastric fluid. 

 Continued in the intestines by the pancreatic 



fluid, and also (probably) by the intestinal 



secretions. 

 Fat globules loosened from their nitrogenous 



cell-walls and membranes by the gastric 



fluid. 

 Digested in the intestines by the bile and the 



pancreatic fluid. 

 Dissolved by the various digestive fluids. 



I Mineral salts 



Absorption by 

 Blood-vessels 



From the mucous membrane in all parts of the alimentary 



canal. 



. No power of selection 

 1 Every kind of food absorbed if dissolved, or if so finely 



divided that it can permeate the walls of the blood capil- 

 1 laries. 



