92 Proceedings of Royal Society of Edinburgh . [sess. 
indication as to the nature of these internal changes is given in 
the above experiments, dealing chiefly with the reactions brought 
about in sea water by the decomposition of the effete products 
thrown into it by animals and by the decay of organic tissues. 
Through the action of the carbonate of ammonia on the sulphate of 
lime in the sea water, it is evident that there is a production of a 
large quantity of carbonate of lime in a form easily available for 
lime-secreting organisms. In the laboratory, when carbonate of 
ammonia is added to sea water nine-tenths of the calcium in solution 
is thrown out as carbonate of lime, while the magnesian salts remain 
in solution ; so that if the reaction above indicated be that which 
takes place in the ocean, then to this circumstance may be due the 
fact that carbonate of magnesia is almost wholly absent from recent 
coral reefs and deep-sea calcareous formations. The above experi- 
ments appear clearly to show that the alkalinity of sea water is due 
to the presence of carbonate of lime in solution ; for, in addition to 
the fact that this body is thrown down from the decomposing 
solutions after these become alkaline, we find that when carbonate 
of lime is added to a neutral artificially-prepared sea water, absolutely 
free from carbonate of lime, it at once gives the alkaline reaction 
common to normal sea water. 
That the amount of the nitrogenous organic matter in a state of 
suspension and solution in the ocean must be enormous, will appear 
evident when it is remembered that the floor of the ocean through- 
out its whole extent is covered with living animals, that the surface 
and sub-surface waters and shallow depths off all coasts are crowded 
with plants and animals down to a depth of several hundred fathoms, 
and that the “ Challenger ” experiments have shown that some 
species of animals flourish in all intermediate depths in ocean water 
from the surface down to the very bottom. The waste products 
arising from the functional activity of these organisms, and the 
nitrogenous organic products arising from the decomposition of their 
dead bodies, must work continual changes on the internal constitu- 
tion of sea-water salts, varying according to their amount, the 
temperature, sunlight, and other conditions. It has been shown 
that ammoniacal salts are to be found everywhere in the ocean, but 
much more abundantly in the warm tropical waters than in the 
polar seas — a result due to the rapid decomposition of nitrogenous 
