124 



THE HUMAN BODY. 



passes through. As there is considerable air dissolved in 

 the water, they can live under it all winter on what oxy- 

 gen they can take in from it through their skins. Man's 



Lung. 



Lung. 



Pericardium. 



Fig. 47. 

 LUNGS IN POSITION, THE WALL OF TUE CHEST BEING CUT AWAY. 



skin is thicker, and does not allow the oxygen to pass 

 through. 



4, Fishes have a peculiar way of getting their oxygen. 

 They, of course, must take it from the air which is dis- 

 solved in the water. On each side of their throats they 



