84 
THE CALIFORNIAN SALMON. 
or ponds, do not grow at the same rate as those of the same 
age in warmer waters. 
In hatching English fish, I should recommend that water 
be used of as low a temperature as can be procured, 
whether from spring or brook. With Californian salmon 
60 deg. is not at all dangerous to the ova, but higher than 
this is probably unsafe ; 55 deg. fco 57 deg. I have found 
to answer well with them, and the fry will live in water 
having a brisk current up to 70 deg., or even to 75 deg. 
But a much lower temperature in dull, sluggish, running 
water would be dangerous, and the young fry have perished 
at once, when placed in water at 80 deg. 
My hatching-apparatus was erected at a small spring, 
trickling down an oozy hollow, and rising out of the side 
of a volcanic hill. To collect the water and protect it 
from the sun, and from pollution by cattle, I formed a 
stone drain about three feet in depth down the channel, 
and collected the water in a small dam, which was 
filled with loose stones and turfed over. The water 
comes through the dam in a galvanised iron pipe, and is 
not exposed to the sun or to the open air until it reaches 
the hatching-boxes. It is perfectly pure and free from 
sediment. The temperature when I first tested it was 
constant for some months at 53 deg., which was a very 
suitable one for fish-hatching. From some unknown 
cause, which, as the spring rises from the side of an 
extinct crater, is probably the result of volcanic action, 
it has risen to 62 deg. in summer, or 60 deg. in winter, 
but the heat is now lessening. The supply is only five 
pints per minute in summer. 
In the stream which runs close by, and which is 
supplied by numerous springs, a constant current runs 
at all times, and I have retained by dams, one above 
another, in its channel, the fiood waters which would 
