VII 



DIGESTION 



93 



the indigestible material that formed part of the foods, 

 as shreds of elastic tissue and hairs from meats, husks 

 or coverings of grains of corn, wheat, oats, peas, and 

 beans, the coloring matter of 

 all greens and vegetables, 

 the hard vegetable capsules 

 that cover the granules of 

 starch in potato, corn, etc., 

 the seeds of small fruits, and 

 pieces of food that were not 

 ground fine enough by the 

 teeth. The liquid is absorbed 

 into the blood, but the solids 

 pass on into the large intes- 

 tine and are expelled from 



,1 i j j -I i , i FIG. S3. Showing the valve be- 



the body daily by this peri- 



J J J tween the small and large m- 



GtaltlC motion. testines. (Drawn by Mater.) 



fa/re. 



SUMMARY OF THE MAIN POINTS 



1. The alimentary canal is a long, muscular tube with en- 

 largements at certain places in which the solid foods are dis- 

 solved so that they can enter the blood. 



2. A gland is a mucous membrane well supplied with blood 

 vessels and nerves that can pick out of the blood certain 

 material to form secretions. The important digestive glands 

 are : the salivary, the gastric, the intestinal, the pancreas, and 

 the liver. 



3. The mouth is the first organ of digestion. Here the 

 foods are cut and ground into fine particles, mixed with saliva, 

 and pushed into the pharynx. In the mouth are the teeth, 

 the tongue, and the tonsils. 



