190 
SALMON. 
difficult to prove. In the Tweed I have killed Grilse early in 
the season so small as only to weigh two pounds, and seen them 
gradually increase in size as the season advanced; the intermediate 
size, however, between the fry and the two-pound Grilse was 
wanting. During the two years in which the fisheries of 
Sutherland have been in the possession of the Duke, a set of 
experiments have been instituted by his factors, one of which 
leaves no doubt upon the subject. Last spring several thousands 
of fry were marked in the different rivers, among others in the 
Laxford and Dinard, on the west coast. In the Laxford the 
first Grilse (marked in April as fry) returned on the 25th. of 
June, and weighed three pounds and a half. Many others were 
got during the season from this weight to six pounds and a half, 
returning to the river where they were marked, which was 
known by a particular mark being used in each, and shelving 
that a return to their breeding-ground Avas as frequent, or rather 
as constant as among the higher animals. The size and weight 
exactly agree with that of the Grilse upon their first running 
elsewhere, and I think that A'ery few attempt to enter the 
rivers before attaining the weight of three pounds.” 
But all the fish which have gone down to the sea are not 
found to return in a proportionate time; and in the north at 
least a succession of them continues through the greater part 
of the summer, Avith an increase of size in the new comers; so 
that by the months of August and September, they are often 
found to be nearly twice as large as those of the early months. 
Some of these, white continuing in the condition of Grilse, have 
been known to attain the weight of fom-teen pounds; but 
perhaps the most remarkable instance of rapidity of groAvth on 
record is given on the authority of the Duke of Athol, (AA^ich 
Ave copy from the “Quarterly Review,” April, 1863.) The 
fish mai'ked was first caught as a Grilse at forty miles from the 
sea on the 31st. of March; at which time it weighed exactly 
ten pounds. It went down to the sea, and returned again in 
the short space of thirty-seven days, when it was again caught; 
and being carefully weighed, the weight was found to be twenty- 
one pounds and a quarter. It has been repeatedly proved by 
marking the fish, that when a Grilse had gone down to the 
sea, it always returns with all the characters of a Salmon. It 
is alro an acknowledged fact that the fish of any age which 
