214 



STUDIES IN PHYSIOLOGY 



Connective tissue 

 on the outside of 

 the windpipe. 



Connective tissue. 



^ Ciliated cells ol 

 / lining of wind- 

 / Pipe. 



FIG. 101. Section of Wall of Windpipe, magnified about 50 times. Photo- 

 graphed through the microscope. 



The lungs are composed of soft pink tissue, easily com- 

 pressed by the hands. If air is 

 forced through a tube inserted 

 in the glottis opening, the lungs 

 swell, and when fully distended 

 they occupy a space several times 

 their size when collapsed. Just 

 as soon as ona ceases to blow 

 into the lungs, one sees that they 

 begin to collapse, and soon reach 

 their former condition. If it 

 were possible for us to trace out 

 the finest branches of the bron- 

 chial tubes, we should find that 



Flo. 102. -Ciliated Cells from each one ended in a branching 

 the Lining of the Windpipe of a ^ r sac W ^j 1 extremely thin walls 

 a Rabbit, highly magnified. , , . , . , TT1 _ 



of elastic tissue. When air comes 



m, 1 m, 2 w 3 =mucous cells in vari- 

 ous stages of secreting mucus, into these air chambers, they are 



