THE NEW AKT OF BKEEDING FISH. 131 



nerally of a brighter silvery hue, than the grilse, the 

 produce of larger growing salmon. The grilse of 

 the rivers Carron and Laxford, in Rosssbire and 

 Satherlandshire, are handsome, small-headed, thick 

 and deep, and short in the body ; their scales are 

 small, smooth and bright, and all this because they 

 are the offspring of small, well-shapen parent sal- 

 mon : whereas the grilse of the river Shin, in which 

 salmon grow to a very large size, are ill-shaped fish, 

 having large heads, long, thin bodies, large long fins, 

 and large, rough, and by no means brilliant scales. 

 It rec[uires experience to distinguish a large and well 

 shaped grilse from a small salmon. Very frequently 

 the only distinguishing marks between grilse and 

 salmon are the smaller scales of the former, the 

 longer and larger fins, and the more forked tail." 

 The powers of digestion of the salmon are amazing. 

 I opine that a salmon would digest a herring in a 

 few minutes, and I think that whilst at sea the quan- 

 tity of fish-food it consumes is immense. Hence the 

 chief cause of the wonderful rapidity of its growth. 

 A salmon never grows so fast as in the second year 

 of its existence. An adult salmon, weighing 101b, 

 has been known to more than double its weight in 

 37 days ! 



This ratio of increase cannot continue long, and 

 I conclude that very large and aged salmon remain 

 stationary as to growth. The male salmon at spawn- 

 ing time, and in its kelt state, has a soft tooth-like 

 excrescence in the lower jaw fitting into the upper. 



