THE CALIFORNIAN SALMON. 
95 
main want of the fish was atmospheric air, or the oxygen 
contained in it. It may seem strange at first sight, that 
fish should need air when they always live in the water, 
and still more so that they cannot rise to the surface, and 
obtain the needed oxygen from the air that is so easily 
within their reach. It is found in practice, however, that 
few river fish will live long in a vessel of still water, unless 
there he a current running into it. It is true that pond 
fish can do so, hut they have the faculty of sucking in air 
at the surface of the water, as may often he seen in the 
glass globes, in which the golden carp are usually kept. 
An interesting experiment is detailed in “ Land and 
Water,” in which a number of adult specimens of salmon, 
perch, black bass, &c., were conveyed from the Atlantic to 
the Pacific Ocean, or from New York to California. 
The fish were carried in a waggon fitted up expressly for 
the purpose, and belonging to the United States Fish 
Commission. Pound the waggon are ranged tanks to hold 
the fish, of a convenient size for moving about in transit. 
Each has a siphon of indiarubber, to allow the water to be 
drawn off and renewed, when necessary, without disturbing 
the fish. 
A special arrangement provides for aerating the water 
during the journey. On one of the axles of the waggon is 
fixed a wheel, which, by means of an endless belt, drives an 
air-pump, which is worked constantly while the train is in 
motion. The air is forced into an indiarubber tube having a 
branch to each tank, each branch being fitted with a stop- 
cock, to regulate the supply of air. By the aid of this 
ingenious arrangement, more than 150 breeding fish of nine 
varieties, were carried without serious loss across the 
American continent. For the sea-fish, a supply of sea- 
water was sent from California to meet them, to renew the 
water on the journey, and which was found of great 
service. 
