398 EB. J ALLEN, 
area of the British fisheries, receives the waters of the Rhine, the Kibe, 
the Thames, and many other rivers. The great cod fisheries off the coast 
of Norway take place in waters which are derived in large part from the 
Baltic current. The Bristol Channel and Irish Sea are other examples 
upon a smaller scale. : 
On the other hand, over the vast areas of the open ocean far from the 
coasts, where the influence of land drainage is not felt and where the 
quantity of minute life in the water is small, no important fisheries are 
carried on. As far as we seem to understand the conditions of the problem 
at present, it does not appear likely that any great fisheries can be devel- 
oped in these open waters. Just as the desert areas of the land, notwith- 
standing the abundant energy of sunlight which falls upon them, are 
unable to support vegetation from lack of water, so it seems these great 
ocean wastes fail in making use of the sun’s power for the production of 
organic life from lack of substances which only the land can supply. If 
this be a true view of the case, when, as will probably happen sooner or 
later, the fisheries of the coastal banks have reached the maximum 
extent of their capacity, we shall have to look for any further increase 
of the supply of fish for food purposes to an extended practice of fish 
culture, a method at present confined almost entirely to fresh-water fishes. 
The extension of fish culture to marine fishes, which are much more 
delicate and difficult to rear than those which live in fresh-water, is by 
no means an easy matter, and much further knowledge will be necessary 
before successful results can be obtained. The researches which [ have 
described to you to-night were commenced largely with a view to obtain- 
ing information about some of the fundamental problems upon which any 
scientific practice of fish culture would need to be based. The investiga- 
tion has at the present time reached only an early stage, but the results 
obtained are unexpected and not without interest. There seems reason 
to hope that a further extension of the work may be of some practical 
importance. 
For a more detailed account of the researches referred to in this address 
see : 
ALLEN, E. J., and Neuson, EK. W., On the Artificial Culture of Marine 
Plankton Organisms, Quart. Journ. Micr. Sci., Vol. 55, p. 361, 
1910, and Journ. Mar. Biol. Assoc., VIII, p. 421, 1910. 
ALLEN, K. J., On the Culture of the Plankton Diatom Thalassiosira gravida 
Cleve, in Artificial Sea-water, Journ. Mar. Biol. Assoc., X, p. 417, 1914. 
