164 THE HUMAN BODY. 



result of all these processes is a thin, milky looking alka- 

 line liquid called chyle. 



Indigestible Substances. With every meal several 

 things are eaten which are not digestible at all. Among 

 them is elastic tissue, forming a part of the connective tissue 

 of all animal foods, and cellulose, which is the chief constit- 

 uent of the cases which envelope the cells of plants. The 

 mucus secreted by the membrane lining the alimentary 

 tract also contains an indigestible substance, mucin. These 

 three materials, together with some water, some undigested 

 foodstuffs, and some excretory substances found in the 

 various secretions poured into the alimentary canal, form 

 a residue which collects in the lower end of the large 

 intestine, and is from time to time expelled from the 

 body. 



Dyspepsia is the common name of a variety of diseased 

 conditions attended ./ith loss of appetite or troublesome 

 digestion. Being often unattended with acute pain, and 

 if it kills at all doing so very slowly, it is pre-eminently 

 suited for treatment by domestic quackery. In reality, 

 however, the immediate cause of the symptoms, and the 

 treatment called for, may vary widely; and the detection 

 of the cause and the choice of the proper remedial agents 

 often call for more than ordinary medical skill. A few of 

 the more common forms of dyspepsia may be mentioned 

 here, with their proximate causes, not in order to enable 

 people to undertake the rash experiment of dosing them- 



Name some indigestible substances eaten in every ordinary meal. 

 Point out the source of each. What indigestible substance is added 

 in the alimentary canal? What substances are found in the lower 

 end of the large intestine? 



What is meant by dyspepsia? Why is it not a wise thing for 

 people to try to treat it themselves without skilled advice? 



