60 
Whoever has watched from a place of concealment 
the trout feeding in an American stream has admired the 
adroitness with which they work down stream, raising 
with their noses the up-stream end of flat stones until the 
current, catching underneath, aids the clever little forager 
to turn over the stone and expose the minute larvee and 
crustacea on which he so voraciously feeds. It is the 
purpose of the process now under consideration to raise 
by artificial means these same species of organisms, and 
in such quantities that the young fry may not only be 
abundantly fed in tanks or small inclosed ponds, but 
ample supplies provided for enriching larger streams and 
ponds where, for some reason, the natural supply may be 
insufficient. 
The apparatus is simple, and visitors properly intro- 
duced have no difficulty in seeing the entire establishment 
at Gremaz, which occupies a gently sloping piece of 
ground, about six acres in extent and watered by three 
springs, which yield collectively about 500 gallons of 
water per minute. The tanks are rectangular excava- 
tions, about 120 feet long by 12 in width, with a depth of 
5 feet. The ground being of a gravelly character it was 
neccessary to line the walls and bottom of some of the 
tanks with cement in order to retain the water, but in 
close clayey earth this would be needless, and the natural 
dirt bottom, if not to muddy, would be preferable to 
cement. The tanks have the same general level and are 
divided by sliding gates of wire gauze sufficiently fine to 
prevent the passage of the fry. Thus far all is simple 
and obvious. The process of Mr. Lugrin. which has 
been patented in several countries, consists in spreading 
upon the bottom of these tanks a material inpregnated 
with the elements necessary to produce spontaneously a 
limitless number of Daphnia, Cyclops, Limnea, as well as 
fresh-water shrimps, and the larvz of various Ephemera 
which form the natural aliment of trout, and other Sal- 
monide at all stages of their growth. Once constructed 
