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 thera 

 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 shewing 

 that a return to their breeding-ground was 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 very 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, with 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, while continuing in the condition of Grilse, have 

 been known to attain the weight of fourteen pounds; but 

 perhaps the most remarkable instance of rapidity of growth on 

 record is given on the authority of the Duke of Athol, (which 

 we copy from the "Quarterly Review," April, 1863.) The 

 fish marked 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 doAvn 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 doAvn to the 

 sea, it always returns with all the characters of a Salmon. It 

 is also an acknowledged fact that the fish of any age which 



