MANUAI, OF NATURE) STUDY. 
101 
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 of 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 thousauds 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 
