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Proceedings of Boyal Society of Edinburgh. [sess. 
of the change in constitution (if any) which lime salts undergo when 
they are carried to the ocean by rivers. Tornoe and others assert 
that the carbonic acid in sea water is in combination with soda; if 
this is so, it follows that the soluble carbonate of lime on mixing 
with the sea water is decomposed by the alkaline chlorides present, 
the result being the formation of chloride of calcium and alkaline 
carbonate. The results we have detailed seem to give some support 
to this view. If this be the case, it points to the necessity for a 
reclassification of the salts as generally expressed in sea- water 
analyses. 
Such a view implies the absence of carbonate of lime from sea 
water, chloride of calcium taking its place, from which salt 
structures of carbonate of lime in a more or less pure state may be 
built up by marine animals and plants. Our results seem to prove 
beyond doubt that all lime compounds, not excepting the carbonate, 
are decomposed during digestion, and appear in the blood in com- 
bination with phosphoric acid as phosphate. Consequently it does 
not seem essential that such animals and plants should obtain the 
lime in the shape of carbonate. 
In the case of the higher forms of crustaceans with their aggressive 
habits, it may be assumed that they obtain a portion of carbonate 
of lime in a concrete form from the animals upon which they prey, 
and this may help in the new formations of this body by them after 
ecdysis, but even then the carbonate of lime must pass through the 
digestive changes we have explained as preceding its reabsorption. 
Of course, it cannot be assumed that coral polyps have such sources 
of calcium carbonate at their command, but, even if their food 
consisted of minute organisms containing carbonate of lime, this 
would only remove the question as to assimilation of one lime salt, 
and its elaboration as another lime salt, from the one animal to the 
other. 
In the blood of these animals we have, in solution, phosphates 
of lime and soda, along with alkaline chlorides, carbonates and 
sulphates associated with albuminous matter, carbonic acid and 
oxygen being also present in varying quantities (in a loosely 
associated or combined condition). This blood when freshly drawn 
is alkaline, no doubt owing to the presence of alkaline phosphates 
and carbonates. 
