16 BRITISH SPORTING FISHES. 
spate will destroy millions of eggs by tearing them 
from the gravel, and a whole host of aquatic 
enemies have to be reckoned with. And this, it 
must be borne in mind, before the fish are hatched. 
The swan alone is able to destroy a gallon of 
spawn a day, and it is aided by other aquatic 
birds. 
The process of hatching is long; but ulti- 
mately the eggs hatch into avelins. These at 
first lurk in any quiet retreat, though as soon as 
the yolk-sac is absorbed, they begin to feed, and 
are termed fry. Until this period they derive 
their nutriment from the yolk, and absorb only as 
much oxygen as will support life. The fry sink 
into the sheltering gravel, get under little rests, 
and only venture out as they see the tiniest bits 
of animal food floating down. If the embryo 
troutlets had enemies whilst still in the egg, they 
have more now. Fry afford delicate morsels to 
predatory water insects, to grebes, ducks, king- 
fishers, herons, and to every mature fish that 
haunts the stream. These have all to be reckoned 
with, and the fry have a hard time of it. By 
this time they have attained to an inch in length, 
and are daily better able to look after themselves. 
As they awake to their active summer life, the 
troutlets find themselves far up the tributaries ; 
and here they will remain until they descend to. 
