210 ON THE GROWTH OF THE SALMON. 



smolts are now in full scale and on their way to the 

 sea; a passage they accomplish, should the water be in a 

 clear state, slowly and circumspectly, and in small strag- 

 gling divisions, but when slightly flooded, with great 

 rapidity and formed into compact shoals and masses. 



There are three distinct species of smolt that at this 

 time descend Tweed. The black-fin or salmon- smolt, 

 the orange-fin or whitling, and the grey-fin or bull- 

 trout smolt. Of these, the last-mentioned far sur- 

 passes in size the two others. I have caught them 

 weighing five ounces, and equal in strength and activity 

 to river-trout of nearly twice that weight. The orange- 

 fin, in this respect, ranks next, and the black-fin or 

 true parr-smolt is the least of all. In Tweed itself, 

 the real salmon smolt abounds more than the others, 

 but in its tributaries, which are spawned in by vast 

 numbers of bull-trout and whitlings, the fry of these 

 fish greatly exceed those of the salmon. 



I am now brought to the investigation of a matter 

 not devoid of difficulty, and where, other modes of 

 ascertaining the truth being withheld, it is allowable, in 

 fact, to supply their absence by mere conjectural state- 

 ments. This, however, I feel averse to do, further than 

 is made actually necessary, and shall therefore, avoid, 

 as much as possible, handling the subject in a purely 

 theoretical manner, as if it were independent of facts. 

 The matter to be investigated is the growth of the 

 salmon smolt, after its entrance into the sea. 



A great many experiments, in various rivers through- 

 out Scotland, have been made in order to ascertain this 

 point in the natural history of the fish. Numberless 

 smolts have been marked and mangled, clipt in the fin 

 and decorated with platina wire, and thus set free to find 

 their way to the ocean, in the expectation of their being, 



