62 
heretofore, in order to get rid of them at the tender age 
when artificial feeding first becomes not only a necessary 
but difficult and troublesome. For these tender nurs- 
lings all open water, particularly when inhabited by older 
trout or other voracious species, are beset with a thou- 
sand dangers which the vigorous yearling is able to escape. 
It is evident from all this that the system practiced at 
Gremaz is equally applicable to the industrial raising of 
trout and other fish for market. and to the restocking of 
streams and ponds for purposes of sport. In the first 
case it is only necessary to provide a series of tanks or 
small ponds from one to another of which the fish can be 
changed monthly, as herein before described, until they 
reach a marketable size; and it is to be remarked that 
trout raised by this method have the natural firmness and 
flavor of wild fish; and not the flabby degenerate char- 
acter of those which have been fed on liver, offal, and 
other unnatural, degrading food. Once prepared, a tank 
or pond is permanently productive. However voracious 
the young fish may be, they leave the bottom of the 
water still peopled with myriads of parent organisms 
which reproduce so rapidly that, before the end of a month, 
the placid water becomes clouded with swarming millions 
of their progeny. The fecal matter dropped by the fish 
during their month of occupancy is sufficient to maintain 
the fertility of the bottom, and thus the system, once 
established, becomes automatic and self-sustaining. 
A single attendant can have the care of a large 
establishment, his only duty being to drive the fish 
periodically from one feeding ground to another and 
close the gate behind them, as a farmer changes his 
flocks from one pasture to another. 
It remains to be explained that while the Daphnia, 
Nais, Cyclops, and other extremely delicate species 
can be profusely grown only in still water, the fresh- 
water shrimp (Gammarus pulex) grows abundantly in 
living streams. At Gremaz rivulets are provided which 
