MANUAI, OP NATURB STUDY. lOl 



The windpipe is a tube that leads downward to our 

 lungs, and it is through it that the lungs are filled 

 with air, and through it the bad air escapes from 

 the lungs. So, you see, it is very important that 

 this tube be kept for the passage of air only. 



Put your hand on your throat and feel that 

 gristly tube just in front o£ the gullet. That 

 tube is the windpipe. Now, the gullet you 

 cannot feel with your hand, for it is just be- 

 hind the windpipe, and extends behind it all the 

 way downward to the stomach. The gullet carries 

 the food, receiving the same as it rolls off the other 

 end of the bridge mentioned awhile ago. Then 

 the bridge flies up again, so that our breathing 

 can continue as before. 



The gullet is composed of thousands of muscular 

 rings around a lining member that is smoother and 

 finer than the lining of your cheek. This inner 

 lining is so smooth and moist that the food, pushed 

 from behind by muscular rings, easily glides along 

 down into the stomach, which is a large room con- 

 taining capacity for three pints. 



How is the lining of the gullet kept moist ? 



But the greater part of our food is solid, such as 

 potatoes, beans, meat, fruits, etc., and can no more 

 enter into the blood, the general circulation, than 

 sand can be taken into the sap of the plant by the 



