46 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
here we are again brought into the presence of that all-important 
element carbon in one of the stages of its beneficent cycle 
through all the so-called elements of the ancients, earth, air, 
fire, and water. 
When, then, the useful carbon dioxide, required as food 
by the developing plants of the sea, becomes stored up im 
increased amount, that causes a marked reduction in the 
alkalinity of the sea-water. The amount of difference between 
any two samples of water may seem small, but the volume 
dealt with in the sea is so vast that the annual turn-over in the 
form of carbon which appears and then disappears, or 1s used 
up, is colossal in amount and difficult to realise—even in the 
narrow seas around our little island. 
The figures that follow are not final, they are still subject 
to correction, but even if not quite exact, will serve as an 
example of the order of quantities involved, and give some 
indication of the vast scale of the phenomenon and of the 
large amount of potential ultimate food-matter available m 
the sea. We find that at Port Erin in March the water not 
only on the shore, but also out in the open sea, is acid to 
phenolphthalein, while a month later it is distinctly alkaline 
to the same indicator, and this change signifies an enormous 
conversion of carbon in the inorganic into carbon in the organic 
form—a, turn-over of such extent that it probably amounts 
to 20,000 or 30,000 tons of carbon per cubic mile of sea-water. 
Or if we think of the carbon as being present in the bodies of 
living organisms, then the weight of these organisms will 
amount to about ten times the above amount, viz., about 
300,000 tons per cubic mile—or if we imagine these same 
organisms distributed along the deepest part of the Imish 
Channel, then they would occupy a strip of water about ten 
miles long by one mile wide, and 88 fathoms deep. Or we may 
imagine this same quantity of carbon as forming the bodies 
of all the organisms found in the sea all around the shores of 
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