living matter divides many times, forming a large number of living 
units or cells, which spread in a thin sheet over the lower surface 
of the egg and gradually extend upwards so as to enclose all the 
yolk. When this living sheet has half covered the egg, a thickening 
appears in it, stretching from the edge toward the centre at the 
lower pole of the egg (see figure 5b). This is the beginning of the 
body of the future fish and it becomes steadily longer and more 
distinct. One end, the head, is soon seen to be larger than the rest 
and in it the eyes appear very early. The smaller tail end lengthens 
very rapidly and grows away from the surface of the egg (see 
figure 5d). At an early stage it acquires a delicate fin membrane, 
which extends along the lower surface and around the tip of the 
tail to the upper surface, where it continues almost to the head. 
The colouring matter, which is chiefly black, appears throughout 
the body and tail in scattered branched cells, and later collects to 
form more or less complete bands across the tail, which are arranged 
in a fashion peculiar to this fish (see figure 5e), there being four, of 
which the first is incomplete above. During this growth the yolk 
has been used up to-form the living matter and the muscles have 
developed on each side of the tail and body until the movements 
of the tail are strong enougn to break the weakened egg membrane 
and allow the fry or larva to escape into the seawater. 
By this time the mouth opening has appeared beneath the head, 
and, since the yolk has been used up, the larva must eat in order to 
keep on growing. At first it feeds upon the minute plants called 
diatoms, which float in the water, but as it becomes larger and more 
active it captures and swallows the small shrimp called copepods, 
that are so abundant in the water and form the ‘red feed’ of the 
herring. It has the curious habit of keeping to a depth of about 
ten fathoms during the day and coming to the surface only at night, 
probably because it is repelled by the strong light of day. The 
older it gets the deeper it goes into the water during the day, until 
finally, as we have observed in the gulf of St. Lawrence, it is far 
from the surface even at night. Whether this is due to the surface 
water becoming warmer or to the older fry preferring the deeper, 
colder, and darker water, we do not know. 
The larva, which on hatching is only about one-fifth of an inch 
in length, does not grow very fast, but it soon takes on a very 
different shape, becoming much deeper and flattened from side to 
15 
