no THE HAUNTS OF LIFE 



It has happened repeatedly that a closed 

 glass thermometer sent down inside a metal 

 tube has been brought up again powdered to 

 a fine dust. In one experiment made on board 

 the Challenger, a thick glass tube full of air 

 was sealed at both ends, wrapped in flannel, 

 and put inside a copper tube with holes at 

 each end. This was lowered to a depth of 

 2000 fathoms, and was then drawn up again. 

 Not only was the glass tube powdered, but 

 the side of the copper case was crushed in- 

 wards by the pressure. Before the empty 

 space caused by the shivering of the glass tube 

 could be filled with water, the side of the cop- 

 per case was stove in an " implosion," as one 

 of the explorers said, had occurred. 



Because of the pressure, deep-sea animals 

 are "liable to an accident to which no other 

 animal in the world is liable that of tum- 

 bling up." Most fishes have a silvery swim- 

 bladder or air-bladder, which contains gas and 

 enables the fish to accommodate itself to dif- 

 ferent depths. But this accommodation must 

 take place very gradually, and if a deep-sea 

 fish, in chasing its prey, rises too high or too 

 suddenly, its swim-bladder expands so much 

 that it cannot be controlled by the muscles. 



