1 08 MA S TIC A T1ON. 



you dissolve some salt or sugar in water, and pour the 

 solution into a bag made of three or four thicknesses 

 of very fine muslin, the salt or sugar will come through 

 just as freely as the water. But if you try the same 

 experiment with boiled starch, you will find that the 

 water comes through, but leaves most of the starch 

 behind it inside the bag. The tiny openings or pores 

 of the mucous membrane lining the alimentary canal, 

 through which the dissolved food has to pass when it is 

 absorbed into the blood, are far smaller than the holes in 

 the finest muslin; and starch, whether raw or boiled, could 

 not get through them. The saliva turns starch into sugar, 

 which dissolves rapidly and is very easily absorbed by 

 the mucous membrane. In this way bread and corn 

 and arrowroot and many other articles of diet which 

 contain much starch (p. 87) are enabled to nourish our 

 bodies. 



19. Why Food should be well Masticated. Some per- 

 sons eat as if all that their teeth and mouth had to do 

 was to bite and swallow : they seem to believe that their 

 stomachs are like the gizzard of a bird, constructed to 

 crush and grind. Nature having provided man with 

 teeth, has given him no gizzard : the human stomach 

 will certainly get out of order if it is frequently called 

 upon to do the work of one. Our molar teeth are so 



Of starch ? How may the pores of the mucous membrane of the 

 alimentary canal be compared to muslin ? How does the action of 

 saliva enable starch to get through these pores ? Why could we not 

 digest bread, corn, arrowroot, and like food without saliva? 



19. What duty besides biting and swallowing have the teeth in 

 connection with digestion ? Where do fowls crush hard food ? What 

 is the consequence if we eat as if we had gizzards ? What is the evi- 

 dent duty of our molars ? How does chewing affect the salivary 

 glands ? 



