420 Prof OS wr UArry W. Thompfion [March 22, 



waters. It was but a few years afterward that Johannes Miiller and 

 others showed that every gallon of the waters over which we sail is 

 a teeming world of microscopic life. A thousand varied forms people 

 the surface waters. Some have their home around the shores while 

 others are denizens of the great ocean currents, and these coming 

 more or less periodically within our reach, mark and render visible 

 the currents to which they belong. Tliese organisms are animal and 

 vegetable, and among them the myriad tiny green algte play their 

 part in the economy of Nature, renewing in the sunlight the oxygen 

 of the sea, as the green herbage restores the balance of oxygen on 

 land. Some few fishes, but fishes of great importance, feed all their 

 lives upon plankton organisms, and their distribution is accordingly 

 closely correlated with the abundance of these. The herring feeds, 

 as many of the great whales do, on the teeming shoals of small Crus- 

 tacea that are especially characteristic of northern seas ; the pilchard, 

 which at times feeds on the same diet, is said to come to the Cornish 

 coasts at the season when minute vegetable organisms reach their 

 greatest abundance. But in early life all fishes whatsoever live on these 

 floating microscopic organisms, on diatom and peridinian and copepod, 

 wliile these same organisms are again the nutriment, direct or indirect, 

 of the multitudinous worm and shell-fish and Crustacea on which the 

 older fishes are in turn nourished. There is another and more difficult 

 chapter still of the same story, relating to those yet smaller organisms, 

 the bacteria, by whose subtle alchemy the nitrogenous contents of the 

 water are controlled, and which lay the first foundations of the ladder 

 by which the inorganic elements pass into the fal)ric of living things. 

 And lastly, among the elements of the plankton must be reckoned the 

 eggs and earliest stages of the vast majority of our food fishes. For 

 it is an elementary and cardinal fact that, with the single important 

 exception of the herring, every food fish of our seas lays eggs, tiny, 

 globular and transparent, which float in the surface waters of the sea. 

 The eggs of the herring, on the other hand (as Walker showed in 

 1803, and as Goodsir and Allman rediscovered), are laid in sticky 

 masses attached to weeds and zoophytes at the bottom. Here they 

 are devoured in quantities by the haddock and other fish, and here 

 tliey may at times be distui'bed by the operations of the trawler, while 

 the eggs of all the other food fishes float safely and undisturbed 

 above. 



But it is high time to pass to the fisheries of the nations border- 

 ing on the North Sea, and to consider their scale and magnitude in 

 the briefest possible review. 



Wherever there is sea-coast there are fishermen, and accordingly 

 all the North Sea nations participate in the fishery ; but the extent to 

 which the fishery is pursued, its actual produce, ;md its importance 

 relatively to the other sources of each country's wealth — all these 

 things differ greatly. 



