THE PHYSIOLOGY OF DEEP-SEA LIFE. 297 
The quantity of carbonic acid in the water is not yet definitely 
settled. Water kept for several years is of no use for analyses. 
Dittmar found that free carbonic acid in sea-water is the excep- 
tion: as а rule, carbonic acid is less than the proportion cor- 
responding to bicarbonate. In surface water the carbonie acid 
increases when the temperature falls, and vice versa. Within 
equal ranges of temperature, it seems to be lower in the Pacific 
than in i Atlantic. The alkalinity of bottom waters was 
found to be distinctly greater than that of surface water. There 
is in sea-water salts a distinct preponderance of free over fixed 
acid, the difference being probably due to carbonates. Dittmar 
says that sea-water, even when alkaline, takes up additional car- 
bonate of lime, if sufficient time is given. 
The only source of oxygen and nitrogen present in sea-water 
is in the atmosphere, their quantity Бейше dependent on surface 
conditions, and not on the depth. Thus, owing to the constant 
oxidation which goes on, sea-water must continually be losing 
its oxygen in proportion to the depth. Dittmar found that 
there was nothing characteristic of bottom waters, as such, in 
regard to their absorbed gases, — nothing to distinguish dion 
фот waters of intermediate depths. With бердй to the ab- 
sorption of oxygen and of nitrogen by sea-water, the amount 
of air which ought theoretically to be absorbed by sea-water 
of the temperature and at the pressure at which samples were 
collected was calculated ; from the quantity of nitrogen found, 
the amount of oxygen hick should be associated viih it was 
reached. 
The quantity of air found is usually less than what is theo- 
retically called for, — prob: Шу from the fact that the water in 
the ocean is always in motion, the temperature and pressure 
varying greatly with the locality. Air is not taken up in deep 
water; it is absorbed elsewhere at the surface, and its presence 
at any point is due to the constant movement of the waters. 
There is no definite relation in the ratio of carbonic acid to 
oxygen present over any area. 16 seems to depend not so much 
on the depth as on the abundance and character of the fauna 
found at certain depths. From the action of the waves, oxygen 
finds its way down from the surface, and is resorbed subse- 
