BY ARTIFICIAL MEANS. 143 



under the gravel, and at least six inches of water must be kept 

 over the gravel. 



In due time that is, in about one hundred and twenty days, 

 more or less, according to a variety of circumstances unnecessary 

 to enumerate the salmon eggs are incubated or hatched, and 

 ascend through the gravel into the waters above the gravel, from 

 which trough, according to the arrangements provided, they may 

 be transmitted into a wide space, such as a wide trough, or, what 

 will far better serve the purpose, a tank or pool, made in the 

 course of a brook, or small stream. Here they must be fed arti- 

 ficially ; and this is the only artificial part of the process of the 

 so-called artificial propagation of the salmon. The food best 

 adapted for them has been found to be beef finely chopped ; on 

 this, it has been, I think, shown they may live for a year ; at the 

 end of which period they undergo the last metamorphosis natural 

 to them during their sojourn in the fresh waters, prior to their 

 descending to the ocean that is, they become suddenly covered all 

 over with silvery scales, and are then recognised and admitted by 

 all to be salmon smolts or the young of salmon or of salmon- 

 trout, no fresh-water trout being ever known to undergo this 

 metamorphosis . 



But prior to the great change, which may indeed be called the 

 great climacteric in the life of the salmon, when in a few days, it 

 may be a few hours, he is about to exchange the crystal streams 

 of a mountain inland torrent for the dark abysses of the briny 

 ocean, in search of food and a feeding-ground wholly unknown 

 to him, peculiar and as yet undiscovered by man; prior to 

 this grand change in the life of the salmon, he has already under- 

 gone, and has still to undergo, many metamorphoses. Losing 

 the long, continuous fins connecting him by the laws of unity with 

 the former world throughout all time, he gradually acquires the 

 fins peculiar to the natural family to which he belongs. When 

 quite young, indeed up to the time he becomes a smolt, the young 

 of all species of the salmonidse strongly resemble each other 

 that is, they have the same system of colouration, of fins, of den- 

 tition. As they grow to maturity, each of the three great natural 

 families lays aside certain characters, retaining those which are 

 peculiar to it. The system of colouring common to all the sal- 



