148 



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 OP -I 

 THE TRUNK 



Thorax or 

 Chest 



Diaphragm 



Abdomen . 



\ Shape 



Walls 



f Conical, with the diaphragm 

 1 as its base. 

 Back Vertebral column. 

 ( Ribs. 



Sides 



Front 



/ Intercostal muscles, 

 f Sternum. 



I Costal cartilages. 

 Floor Diaphragm. 



(A muscular partition, dividing the thorax 

 from the abdomen. Convex above and 

 concave below. 



f Roof Diaphragm. 

 I Back Vertebral column. 

 1 Sides arid Front Abdomi- 

 L nal muscles. 



Walls 



Absorption by 

 Blood-vessels 



f Solution commenced in the mouth by the 



Starchy foods \ saliva. 



1 Completed in the intestines by the intestinal 

 I juices. 

 Solution commenced in the stomach by the 



gastric fluid. , 



Continued in the intestines by the pancreatic 

 fluid, and also (probably) by the intestinal 

 secretions. 



f Fat globules loosened from their nitrogenous 

 cell-walls and membranes by the gastric 

 fluid. 



| Digested in the intestines by the bile and the 

 I pancreatic fluid. 

 Mineral salts Dissolved by the various digestive fluids. 



From the mucous membrane in all parts of the alimentary 

 canal. 



No power of selection 



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

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

 laries. 



