66 THE SALMON. 



contrast, or contrasts, shown as to season, l)etween grilse, 

 and not only salmon, but also trout. It will be under- 

 stood that the theory which we support assumes the 

 salmon column to comprise only the adults of a certain 

 species, the grilse column the youth of the same species, 

 and the trout column both the adults, and, for part of the 

 season, the young, of quite another species ; whilst Mr. 

 Mackenzie's theory assigns to the salmon and the grilse 

 columns respectively both the young and adults of a dis- 

 tinct species. Now, let us see whether the facts ascer- 

 tained are most reconcilable with our theory or with 

 Mr. Mackenzie's — with the old orthodoxy or the new 

 heresy. The most important contrast lies in the fact 

 that, whilst (doubling for the odd half month) 44 in 

 each 1000 of salmon, and 16 in each 1000 of trout, 

 are captured in February, and the take of both goes on 

 increasing till, in May, salmon have reached the propor- 

 tion of 128, and trout of 56 per 1000 ; grilse, on the 

 other hand, are entirely absent in the first three months 

 of the season, all but entirely absent in May, and show 

 but a small advanced -guard even in June. These facts 

 are at least reconcilable with, if they are not demon- 

 strative of, the theory that the grilse is a young fish, 

 performing its first ascent. Grilse do not ascend, as do 

 salmon and trout, in February, March, April, or even (in 

 the case of Tweed) May, because they are then only 

 descending in the condition of smolts, or are undergoing 

 their growth and transmutation in the sea. 



Or look at the figures of the latter portion of the 

 season as above exhibited, and they will be found to 

 witness to the same efiect, though not quite so conclu- 



