THE WHALES. 31 



second place, it acts as a safeguard against the tre- 

 mendous pressure of the water at the depths to which 

 the whale descends. 



Whales have been known to dive perpendicularly, 

 carrying with them such a length of line that if a bottle 

 had been sunk to the same depth, corked, sealed, and 

 closed in every way, the water would have forced its 

 way through everything, and filled the bottle. Pieces 

 of wood that have been sunk to such depths are found 

 to have the water driven into every pore, so that they 

 can no longer float, but sink as if they were bars of 

 iron. 



Such a pressure as this, if exercised directly upon 

 the body of the animal, would be fatal, but the thick 

 elastic coat of blubber yields to the weight of water, 

 and is itself compressed without transmitting the 

 pressure to the vital organs. 



The reader may, perhaps, ask how it is that the 

 aperture of the nostrils can be sufficiently closed to 

 keep the water from forcing its way into the lungs. 

 This is done by means of a beautifully-formed valve, 

 which can only be opened by force applied from below, 

 and is spontaneously closed by force applied from 

 above, fitting more and more tightly in proportion as 

 the pressure increases. 



Thus we see that although we cannot, without her- 

 metically sealing it (i.e., fusing the glass together), 

 close a bottle so tightly that the water cannot force its 

 way through the obstacles, the living whales possess a 

 self-acting valve through which they can respire when 

 at the surface, but which is absolutely impervious to 

 the water, no matter at what depth the animal may be. 



