334 THE WORLD OF THE SEA. 
thousand causes tended to destroy their offspring, they would 
multiply beyond all conception. An immense number of eggs 
never hatch; the currents disperse them, the tempests injure them, 
the sun dries them, and other animals destroy them. Hardly one 
egg out of a hundred produces an embryo, and thousands of the 
little fry are devoured. The chances of existence are so much 
against them, that in this we can see the reason why they are 
so prolific. It has been calculated that— 
The red mullet produces ... a a ae $1,586 eggs. 
The sole se S56 ‘A an mae 100, 362 
The mackerel ... et te hse es 546, 681 
The carp ee ee an si ts: 700, 000 
The sturgeon ey = se ee as 1,467,856 
The plaice * cb = BF ... 6,000,000 
The turbot ans ae a a ... 9,000,000 
The grey mullet ... se ye st ... 13,000,000 
Soon after the egg has been laid, there appears upon the surface 
of an interior globe a white spot, which upon close examination 
appears like several small drops of oil; in some eggs one or two 
hours are sufficient to produce this spot, but in salmon roe it does 
not make its appearance for eight or ten. The interior membrane 
begins to fold itself, at first enwrapping half the egg; this coat 
increases until only about a tenth of the interior globe is visible, 
and this begins to give signs of organisation. In a little time the 
embryo can be discerned occupying a quarter of the circumference 
of the egg; gradually the form of the little fish appears, with its 
eyes as black points. After this the hatching is soon completed. 
This process requires a week in the case of the carp, twenty days 
in the roach, and two or three months in the trout and salmon. 
Generally, the young fish swim off as soon as they are hatched. 
The salmon fry, when they come out of the egg, carry a large 
bladder-like vesicle attached to the abdomen. This seriousiy 
encumbers their flight from their many enemies, but it contains 
nourishment by which the young fish is supported until it can 
feed itself. Until this time, it hides itself away, even from the 
light, dwelling in seclusion five or six weeks. Ordinarily, the 
mother takes no care of her progeny, and yet there are exceptions 
to the rule. 
The Hassar (Doras costata), whose travelling propensities we 
