ii4 HUMAN PHYSIOLOGY CHAP. 



90. Diseases of the Alimentary Canal. We have seen 

 that many disease germs enter the body with the air 

 we breathe and cause certain diseases of the air pas- 

 sages. The alimentary canal is another important 

 channel through which thousands of bacteria get into 

 the body daily. The germs of typhoid fever, dysentery, 

 and cholera can get into the body only by this means, 

 while those of consumption, diphtheria, and scarlet 



FIG. 58. Bacteria of typhoid fever (Pratt). 



fever may enter the body either with the air or with 

 the foods. These diseases will be discussed in a later 

 chapter. 



Among the other important ailments of the diges- 

 tive tract are dyspepsia, intestinal indigestion, liver 

 trouble, and appendicitis. Dyspepsia is a disease of the 

 stomach and may be due to a great variety of causes, 

 but the most common are coarse, indigestible, poorly 

 cooked articles of food, rapid eating, bad teeth, insuf- 

 ficient mastication, lack of variety in diet, and excessive 

 use of alcoholic beverages. If our foods are plain and 

 wholesome, varied more or less from day to day, prop- 

 erly cooked, eaten slowly, well masticated, and the amount 

 taken not too large, the stomach will do its work well. 



