HABITS OF MARINE ANIMALS 155 
plankton must be added the myriads of floating eggs 
and helpless larve of marine fishes. 
Transitory plankton, as will be seen later, materially 
adds to the food supply in the sea, and, further, the 
fact of its drifting about has an important bearing on 
the distribution of various forms of marine life. As 
the seeds of plants and trees on the land are carried 
hither and thither by the wind, so similarly the larve of 
marine animals are carried through the ocean by tides 
and currents. In this manner marine life is main- 
tained in more or less the same proportions all over the 
world, whatever may be the agencies working for its 
destruction. 
As the pastures of the land die down in winter, and 
life hes dormant, so in the sea plankton dies down; 
but the sea is never altogether sterile, for copepods are 
always present, as well as many other varieties of small 
crustaceans. 
With the advent of spring, the sea is flooded with the 
eggs of spring-spawning fish, such as the plaice, the 
haddock and the cod, and these very soon hatch into 
the various larval forms. Simultaneously the minutest 
forms of plankton life (protozoa and diatoms) increase 
in the miraculous manner described; while the larvee 
of the barnacles, sea-squirts, crabs and copepods appear 
in their myriads. In June, July and August the sea 
is full of the eggs and larvee of summer-spawning fishes, 
such as the ling, the mackerel, the turbot, and the sole. 
The diatoms have now eased off and though the crab 
