FOOD FROM THE SEA. 385 
cambe Bay, with a yearly production of 10,000 Ibs. per acre; then in 
quite a different category :— 
Fish from Carp Ponds... . 95 Ibs. per acre per year. 
Fish from the enclosed Harbour . 89 Ibs. _ ,, - 
Beef from Young Bullocks .. *. 731bs. —.,, 2 
Fish from the NorthSea . . . 15lbs. _,, is 
It will be seen, therefore, that although the figures for the open sea 
are far below those for cultivated land, more restricted areas of water are 
capable of producing a considerably greater weight of crop. Especially 
the figures for the mussel beds seem to indicate that much larger returns 
from the sea might be possible, if sufficient knowledge of the complex 
conditions of marine life could be successfully obtained. 
The possibilities of a still greater yield have recently been suggested 
by Prof. Benjamin Moore of Liverpool, from observations made in the 
Irish Sea. This author has calculated from measurements of the change 
in alkalinity of the water, that under the action of sunlight there is an 
annual production of two tons of dry organic matter per acre, which 
would be equivalent to at least ten tons of moist vegetable substance. 
This is a preliminary estimate to which it would be unwise to attribute 
too great exactitude at present, but it does seem to confirm the view that 
Wwe are as yet a very long way indeed from making full use of the organic 
food substance which the seas around our coasts are capable of pro- 
ducing. 
And this leads me to ask your attention in a little more detail, to the 
particular aspect of the conditions upon which marine life depends, to 
which my own researches have recently been directed. 
The marine vegetation, which constitutes the fundamental food supply 
of the sea, may be divided into two principal groups. All round our 
shores we find attached to the sea-floor the green, red and brown sea- 
weeds. These form a fringe in the shallow water around the coast, but 
do not extend to a greater depth than about 15 fathoms, owing to the 
fact that sufficient light to enable them to grow does not penetrate 
through the water below this depth. Many animals feed upon these 
seaweeds as they grow, and recent researches by Danish naturalists seem 
to show that when the weeds die and decay the organic fragments into 
which they break up constitute an important source of food for many 
other animals, which in their turn serve as food for fish. 
Outside this coastal fringe, however, the plant life of the sea consists 
of minute organisms, microscopic in size, which float freely in the water, 
and live and grow in the upper layers from the surface to a depth of 
100 or 200 fathoms, or even deeper. Amongst these microscopic plants 
NEW SERIES.—VOL. XI. NO, 8. DECEMBER, 1917. 2C 
