THE PHYSICAL CONDITIONS OF THE ABYSS 21 



to sustain, and the tube had suddenly given way and 

 been crushed by the violence of the action to a fine 

 powder. So violent and rapid had been the collapse 

 that the water had not had time to rush in by 

 means of the holes at both ends of the copper cylinder 

 and thus fill the empty space left behind by the 

 collapse of the glass tube, but had instead crushed 

 in the copper wall and brought equilibrium in that 

 manner. The process is exactly the reverse of an 

 explosion, and is termed by Sir Wyville Thomson an 

 " implosion." 



It is but reasonable to suppose that the ability 

 to sustain this enormous pressure can only be acquired 

 by animals after generations of gradual migrations 

 from shallow waters. Those forms that are brought 

 up by the dredge from the depths of the ocean 

 are usually killed and distorted by the enormous 

 and rapid diminution of pressure in their journey 

 to the surface, and it is extremely probable that 

 shallow-water forms would be similarly killed and 

 crushed out of shape were they suddenly plunged 

 into very deep water. The fish that live at these 

 enormous depths are in consequence of the enormous 

 pressure liable to a curious form of accident. If, in 

 chasing their prey or for any other reason, they rise 



