APPENDIX. 205 



self that he threw his line over will never come back ; 

 it is dispersed round and round the world by this time. 

 There is nothing more certain than that circumstances 

 precisely similar will never concur again. What are 

 the essential circumstances ? Nobody knows. The in- 

 terdict, to the unassisted human faculties, is perfectly 

 unintelligible." So Lord Ardmillan thought; and, 

 taking off the interdict, made the owner of the salmon- 

 fishing pay for his whistle in the law-courts. 



C. GROWTH AND HABITS OF THE 

 SALMON. 



We have mentioned (vide p. 126) that the experi- 

 ments which have been made in the Tweed to ascer- 

 tain the period of growth between the Smolt stage and 

 the Grilse stage have invariably led to the conclusion* 

 that the smolts which leave the river in the beginning 

 of summer remain in the sea for a year before return- 

 ing as grilse. In a report presented to the Tweed 

 Commissioners by Mr. Mitchell, their Superintendent, 

 in the autumn of 1858, additional facts, which are 

 clearly stated and apparently impregnable, are brought 

 to bear upon this point. He says 



" The mark which I adopted for smolts during the spring of 

 last year (1857) was a small piece of fine silver wire which I 

 inserted into the jaw of the fish. In the salmon smolts I at- 

 tached the ring to the lower jaw, and in the smolts of bull 

 trout or salmo eriox, I attached it to the upper jaw. The- 

 manner of performing the operation was by perforating the 

 jaw, then inserting a straight piece of wire, which was then 

 twisted together at both ends, after which it formed a kind of 

 loop or ring. On the 30th of May in that year I marked 231 

 salmon smolts, and on the 15th of May I marked other 48 in< 

 all 279 ; and last named day I marked 60 bull trout smolts in 

 the manner described above. 



" Of those so marked, three have been caught, bearing the 

 marks. The first caught was a bull trout, 3 ft>s. weight, which 

 was taken at the Carr Rock Fishery at Tweedmouth, on the 



