XI 
THE INTERNAL ECONOMY OF THE SEA 
4 
O one can forget the first sight of a big catch 
laid out for sale at one of our chief fishing 
ports. There are tons and even miles of fishes, 
recently representing enormous locomotor power in 
the sea, and soon to be transformed into likewise 
enormous, though reduced, power of muscle-work 
and brain-work on land. The sweepings go to feed 
cattle and to fertilize the ground, and the total 
supply is in such abundance that we stand wondering 
at its continuance from day to day, year in year 
out. What happens in the vast economy of the 
sea? Who are the producers, the consumers, and 
the middlemen? A_ well-known instance will 
illustrate our inquiry—namely, the demonstration, 
offered some years ago by Dr. E. J. Allen, the 
Director of the Marine Biological Station at Ply- 
mouth, that there is a close correlation between the 
sunshine records for May and the quantity of 
mackerel at Billingsgate. The rationale of this is. 
instructive. Mr. G. E. Bullen showed that there 
is a correspondence between the catches of mackerel 
during May and the amount of the Copepod plank- 
ton (i.e. small Crustaceans of drifting habit) upon 
which the mackerel for the most part feed. Then 
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