76 
THE CALIFORNIAN SALMON. 
placed, and the box had been kept in an ice-house with 
a uniform temperature of 32 deg. or 33 deg. Of these ova 
94 per cent, arrived in good condition, and over 50 per cent, 
hatched out successfully, the hatching commencing at once 
when they were placed in the water, and going on without 
interruption till all were hatched, the incubatory process 
having been almost completed in the moist air of the 
ice-chamber. 
FISH HATCHING IN A CURRENT OF WATER. 
The natural way in which the eggs of trout and salmon 
are hatched, is by the action of a current of water flowing 
over them, and the ova of the salmon, salmon-trout, sea- 
trout, as well as of all the other varieties of river and lake 
trout, are deposited by the parent fish in natural gravel 
beds, in shallow parts of the streams and rivers, where the 
current runs swiftly. In cold latitudes, where the rivers 
are often frozen over in winter, the shallows having a 
rapid current are seldom frozen, and the constant supply 
of atmospheric air necessary, as well to the development of 
the ova, as to the existence of the fish, is kept up by 
the running water, which by rippling over the rapids gets 
aerated, and maintains the necessary supply of oxygen, 
obtained from its contact with the atmosphere, which is 
essential to the vivification of the ova. 
It probably happens sometimes, that ova which are 
covered with gravel, may by the subsidence of the stream, 
be left above the level of the water ; and if the gravel in 
which they are imbedded continues sufficiently moist, these 
eggs may hatch out safely, and the alevins may reach the 
water immediately after being hatched ; but this must be 
a very exceptional case, and I cannot imagine such a 
