THE PHYSIOLOGY OF DEEP-SEA LIFE. 303 



oceanic basins. And this is the temperature of all seas which 

 are not, like inland seas, subjected to special conditions ; as, for 

 instance, the Mediterranean, the Red Sea, the Sulu Sea, the Car- 

 ibbean, and the Gulf of Mexico. These all depend for their 

 lowest bottom temperature on the height of the ridges separat- 

 ing them from the general circulation. 



The differences of temperature observed over extensive areas 

 in the Atlantic are easily explained by the presence of ridges 

 rising to heights which isolate the western basin of the Atlantic 

 from the eastern, and that protect these basins again from the 

 indraught of cold water from the depths of the South Atlantic. 

 We may thus find enclosed seas or circumscribed oceanic areas 

 with higher bottom temperature than adjoining seas, due en- 

 tirely to their exclusion from oceanic circulation by elevations 

 of a portion of the bottom. 



The great cold of the bottom water of the ocean, even in the 

 tropics, is best brought home to those who have examined the 

 contents of a haul of the trawl under the tropics. The bottom 

 ooze is intensely cold, and it is a strange sensation, while one's 

 back is broiling beneath a tropical sun, to have one's hands 

 nearly frozen from the stiff, cold mud or ooze one is compelled 

 to handle while assorting the contents of the trawl.* 



The increase of temperature as one passes into the interior 

 of the earth does not affect the temperature of the bottom 

 of the ocean, for there the constant renewal of cold water sup- 

 plied from the poles keeps the temperature uniform even in the 

 equatorial regions. Were the body of water affected in a sim- 

 ilar manner as the solid crust of the earth, we should find about 

 350° F. at a depth of three thousand fathoms. But if the in- 

 creased heat of the interior of the earth's crust is due to pres- 

 sure, and not to solar agency through the absorption of heat, we 

 can see some reason for a lower ocean temperature at correspond- 

 ing depths, even were there no oceanic circulation. 



1 We followed the advice giveu by Com- eucouraging to the friends of total absti- 



mander Belknap to dredgers and sound- nence. It came back to us cold, it is 



ers, to ice their wine in the common true, but filled with muddy salt water, 



refrigerator ; but the fate of a small hot- whicli had been forced through the foil 



tie of champagne, sent down to a depth and cork, and had replaced the more pala- 



of twenty-four hundred fathoms, was only table contents of the bottle. 



