THE SCALES OF THE SALMONID^ 253 



portion, and thus, as the salmon grows, the nucleus gradually 

 loses its central position in the scale, and tends to approach 

 the posterior edge (see Plate XXX.). 



It will also be noticed that the annular bands added to 

 the scale are of varying numbers, and width, and if they 

 are carefully examined it will be seen that the alternate 

 occurrences of the wider and narrower bands form a series, 

 and each complete series of such varying widths of these 

 annular markings indicate the age as well as the annual 

 increase in the size of the fish. 



I consider the explanation generally given by modern 

 writers as to the individually varying size of these 

 additions to the scale of a salmon worth consideration. 



It is said that the annual periods of decrease in the size 

 of the scale bands is due to the limited food supply to be 

 found during each winter in the sea. As we do not know 

 where the salmon goes to during his summer and winter 

 sea life, we cannot know whether or not his winter habitat 

 is less happily provided with food material than his summer 

 quarters, and therefore if some other reason will provide a 

 more satisfactory explanation I think it is worth examination. 



It has been proved that a salmon, if kept in fresh water, 

 and isolated, will year by year, as the spawning season 

 comes, develop the condition of a spawning salmon, will 

 neglect its food, will suffer in appearance, etc., and we can 

 safely assume that salmon in salt water, even if they do not 

 visit the coast,* also develop certain of the genital changes 

 associated with the creation of ova, as each spawning 

 season approaches, i.e., winter time, and it is not improbable 

 that at such times, as with all other fish, their appetites 



* It may be that most if not all the fish of each year's batch of smolts may 

 visit our shores as shoals of grilse or young salmon, but that many members of 

 each such shoal may either be unable to ascend, or not in a condition to wish 

 to ascend, the river of their birth, and that these return to the sea until a 

 more favourable opportunity. 



