.1889-90.] Dr J. Murray & Mr R. Irvine on Coral Beefs. 91 
much more probable that the reactions indicated by the above 
experiments render the whole of the lime salts in the sea water, and 
especially the sulphate, available for the coral polyps to construct their 
massive structures. In higher animals, like hens, the carbonate of 
lime is secreted from the blood ; but in coral polyps, in which there 
is no true circulatory system, and where the animal is immersed in 
the sea water, it is most probable that the reaction above referred 
to — the formation of carbonate of ammonia — is in every way advan- 
tageous to these lime-secreting organisms, and facilitates the deposi- 
tion of carbonate of lime by the protoplasm. In the case of all the 
lower classes of lime-secreting organisms this change in the con- 
stitution of the lime salts may take place within the tissues of the 
animals. In the case of the oysters (Exp. VII.) the excess of car- 
bonate of lime observed in the liquor or diluted lymph was clearly 
due to the decomposition of the sulphate of lime in the sea water by 
carbonate of ammonia secreted as such by the protoplasm of the 
animal. 
The quantity of salts in a given volume of sea water varies with 
the position from which the sample is collected, and according as 
the salinity is high or low ; but it has been shown, by hundreds 
of analyses from all parts of the ocean, that the actual ratio of 
acids and bases — that is, the ratio of the constituents of sea salts 
— is constant in waters from all regions and depths of the ocean, 
w T ith one very significant exception, namely, that of lime, which 
is present in slightly greater proportion in water from the greater 
depths. In the ordinary analyses, however, the rarer elements 
are never determined, although it is known that there are traces 
of nearly every element in sea water. Theoretically, every base 
may be combined with every acid, and the whole solution must 
be in a continual state of flux as to its internal constitution. An 
“According to these results, an oyster would appear to be a pumping- 
machine of extraordinary activity 
“ It is also known that in the testacea there is a continual current of water 
from behind forwards within the mantle 
‘ ‘ This current of water in the oysters appears to be astonishing when we 
compare it with the quantity of fluid which passes through the human body. 
“ When a man weighing 150 lbs. consumes even 5 lbs. of liquid daily during 
a period of seventy-five years, still a quantity of liquid, only 912*5 times the 
weight of his body, would pass through his organism, or only about uV to ws 
of the sea water which has passed through the oysters.” 
