290 How to obtain it. 
little fish lose their trout-like appearance, including the bars, or 
“finger marks,” and that they become bright and silvery. They 
are then called smolts, and are generally supposed to have got a 
fresh set of scales, but this is not so. Their shining appearance 
is caused, not by new scales, but by a silvery pigment secreted 
on the undersides of the scales. This same silvery appearance 
also affects the gill covers or opercles, which are not possessed of 
scales. 
An interesting experiment was tried some years ago. A 
number of salmon “parr” were taken from the river, and placed 
in a fresh-water aquarium tank. In due course about half of them 
assumed the smolt stage, but the others did not. Sea water was 
then added until the other was displaced, and, on the water 
becoming salt as the sea itself, a very interesting result occurred. It 
has been asserted that “ parrs,” as such, will not live in salt water. 
These not only lived, but very soon assumed the smolt stage. 
We know that salmon “parrs” and smolts when in a river feed 
voraciously, for they will take nearly any bait. They are found 
gorged with shellfish, larvee of insects, etc. So voracious are they 
that we know full well that they often spoil the sport in a river. 
Can it be supposed, for a moment, that a salmon in these early 
stages, during which periods of its existence it does not make any 
great growth, feeds voraciously, and, after going to the sea, takes 
either no food or very little, notwithstanding that the “smolt” 
which leaves the river weighing only a very few ounces, returns 
very soon as a grilse of several pounds? It seems unreasonable. 
Some smolts return from the sea as grilse in about three 
months, whilst others of the same brood remain in the sea for 
about fourteen or fifteen months. Those which return in about 
three months have, taking a very low estimate, reached a weight 
of some three pounds, but those which remain for fourteen or 
fifteen months do not necessarily attain a very much greater size 
than those which return in the shorter period. The same 
peculiarity is noticeable to an extent amongst trout. Some 
grow very much more rapidly than others. A smolt let off at 
Stormontfield in May returned in July of the same year, weighing 
about three pounds. On the other hand, one which the Duke of 
Roxburghe let off on May 14th did not return till July of the following 
