Lxviii BREEDING. 



Sars in Norway found some to hatch on the eighteenth day. The eggs of 

 the haddock in the United States required an average of nine days, and the 

 shortest period observed was eight days, while those of the coal fish, Gadus 

 pollachius, hatch in four or five days in water of modei^ate temperature. 



But if we can find such a difference in the cod family as to the time- 

 required for incubation to be from four or five days to six weeks, still greater 

 variations are perceptible among those of the' salmon family. At Howietoun 

 the eggs of the smelt, Osmerus eperlanus, kept in the trout hatching house, 

 took about forty-two days, but on the water being a little warmer they came 

 out by the thirty-fourth day. In the same establishment, with the water 

 kept at about 44*1 degrees, the brook and other trout took from seventy-one 

 to seventy-two days ; the American char, Salmo fontinalis, seventy-three ; 

 and the salmon seventy-seven. But the foregoing are subject to wide 

 variations of time (by decreasing the temperature of the water), as of the 

 trcut up to 114 days, and the hatching of the salmon has been delayed to 

 the' 145th day, or even more, and acting upon this knowledge the eggs of 

 members of the Salmonidce have been transmitted in safety to the Antipodes. 



Here I would draw attention to the various attempts which have been 

 made to prove that salmon can breed in salt water, a proposition advanced 

 by some estuary and shore fishermen, apparently in order to show that there 

 is no necessity to have any restrictive legislation on salmon fisheries, but 

 that everyone should be permitted to fish as he pleases, while the fish ought 

 to continue their species in the sea and their young to ascend rivers to be cap- 

 tured- a view long since shown to be entirely erroneous, and which is referred 

 to in vol. ii (p. 63). In fact, with the exception of catadromus forms, 

 as the eel, we do not possess any fresh-water fishes that breed in salt water. 



At the Fisheries Exhibition of 1883, the Commissioner from Canada, 

 Mr. Wilmot, informed us that salmon can be detained in salt water until 

 ready to be stripped of their ova and milt, which can then be raised in fresh 

 water. But several experiments have all ended in one result, the eggs 

 having died in salt water, as have also all the young; consequently, if salmon 

 from any cause are prevented ascending rivers, and have to drop their eggs 

 in saline or brackish water, no young will be hatched, while eggs or young 

 placed in brackish or salt water will die. 



I remarked in 1882 that at Sir James Gibson-Maitland's fish-ponds 

 at Howietoun, the Lochleven variety of trout produced eggs' of different 

 sizes in accordance with the parents' age. Thus fish hatched in 1876, or 

 six-year-olds, gave ova, thirty-two of which filled the length of a glass grill, 

 whereas those females which had been hatched in 1875, or seven-yeai'-olds, 

 furnished eggs twenty-seven or twenty-eight of which occupied the same 

 space. Not only does this occur in the Lochleven variety, but also in the 

 brook trout and the American char ; and Dr. John Davy found among 



