THE CALIFORNIAN SALMON. 
97 
point is to keep up a constant supply of air in the water. It 
is found that water is composed of rounded globules, which 
admit of a certain quantity of air in the interstices. Fish 
require oxygen, which they respire by their gills, which 
fulfil the functions of the lungs in the mammalia. When all 
the air, the quantity of which is very limited, which is con- 
tained in a vessel of water, has been deprived of its oxygen 
by being breathed over *in passing through the gills, the 
fish must become suiFocated, as certainly as would a human 
being, if shut up in a close box without fresh air. There are 
fish, such as the golden carp, that do not suffer in this way, 
as they can come to the surface and obtain a supply of 
oxygen, but active fish such as salmon and trout, which are 
accustomed to highly aerated water, in the rapid rivers, or 
the seas which they frequent, perish very quickly if confined 
in a small vessel of water without a current. The remedy is, 
to give a supply of air at intervals, and the simplest and 
most effective method, of attaining this object, is by using a 
strong pair of bellows, and an indiarubber tube about 
two feet in length, to force the air to the bottom of the 
fish-can. 
The tube should be corked at the end, and pierced with 
a number of minute holes with a fine wire made red hot, 
so as to bring the air into contact with as large a surface 
of water as possible. When fish turn on their sides, 
and are perishing for want of air, a few strokes of the 
bellows act upon them like magic, and they immediately 
recover. In practice, I used the bellows every 15 minutes, 
although less frequeutly would probably have done equally 
well, but it is better to err on the safe side. 
In the transport of fish, the danger increases greatly 
with high temperatures. In distributing the Californian 
salmon, I kept them at the temperature at which they had 
been hatched, and to which they had afterwards beenaccus- 
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