TEMPERATURE AND MOYEMENTS OF THE DEEP SEA. 
135 
do with it. These depths are stagnant ; there is nothing to 
change them ; for they are completely cut off from the depths 
of the Atlantic ; and the only vertical circulation to which they 
are subject consists in the descent of water which has been con- 
centrated by evaporation on the surface, and which, becoming 
heavier by concentration, will go down, but will soon diffuse its 
excess of salt, so as not to reach any great depth. Thus it is 
obvious that the condition of any “ self-contained ” basin, like 
the Mediterranean, must be extremely different Biologically, and 
therefore Geologically, from that of an Oceanic basin forming 
part of the great Water-system of the globe. 
