GENERAL BIOLOGY 



72. 



These figures show a minimum below 100 metres, and a 

 maximum between 500 and 1000 metres. Comparing this with 

 the curves for specific gravity at these two stations (Figs. 516 

 and 517), we notice a pronounced rise in specific gravity in the 

 upper 100 metres (the plant region), followed by a very slow 

 rise and then a rapid rise towards 1000 metres, beyond which 

 the specific gravity becomes very uniform. The temperature, 

 which greatly influences the viscosity, falls gradually, correspond- 

 ing to the rise in specific gravity, and in consequence the 

 viscosity increases towards deep water. 



t" = ZO' 19° 18" IT 



St SO 



S 9Z7o 



li' IZ" 11" , 



Fig. 517. — Curves of Temperature (/°) and Specific Gravity (o-,), Station 50. 

 (South of the Azores.) 



Off" the banks of Newfoundland we took the following series 

 at Station 80 : 



235 to o metres gave 5 c.c. containing 16 species of Crustaceans. 

 525 to 235 „ 45 „ 27 



950 to 525 „ 28 „ 34 



The curve of specific gravity here (see Fig. 518) is 

 essentially different from those in the Sargasso Sea, for a rapid 

 rise occurs down to about 500 metres, beyond which the specific 

 gravity becomes practically uniform, and at this station no 

 minimum quantity of organisms is noticeable between 500 and 

 200 metres, but on the contrary a considerable rise. 



