294 THE ZOOLOGIST. 



gently into each, and if they should appear too much exposed, 

 by waving his hand in the water they readily sink under cover 

 of the larger stones as if by instinct. The labour for a time is 

 now over, and the water-supply of the boxes alone requires 

 attention. 



During severe winters various precautions are necessary ; 

 thus the ice on the mill-lade may block the current to the 

 filtering-pond, and boards and straw may be required to protect 

 the hatching-boxes from consolidation, which, in the case of the 

 pelagic eggs of marine fishes in a tank, is so fatal. The fisher- 

 man feared that similar effects would ensue in the instance of 

 the ova of the Salmon, but actual experiments cannot at this 

 date be recalled. Moreover, a flock of ducks has been known 

 during severe weather to devour all the eggs they could secure 

 — just as Scoters and other forms at sea people a long line of 

 floating organisms and greedily swallow the pelagic eggs of fishes. 



Toward the middle of January the eyes of the embryos are 

 visible, and about the 8th of April the earliest are hatched, the 

 larvae with the large yolk-sac keeping the protection of the 

 stones in the boxes. Those whicb, after struggling inside the 

 transparent capsule, emerge head first, with a few wriggles 

 shake off the capsule and are free, represent the normal births. 

 On the other hand, those which emerge with the tail first are 

 less fortunate, for the egg-capsule clings round the yolk-sac and 

 the head, and may cause the death of the young fish. In mild 

 winters hatching occurs about thirty days sooner than in a 

 severe one. 



At this stage the little Salmon is in a rather helpless con- 

 dition, though its mouth is open and it is capable of wriggling, 

 and in its native rivers must be liable to many mishaps from 

 spates in the mud, predatory birds, fishes and invertebrates. 

 In the boxes they remain quiescent for six weeks longer until 

 the large yolk-sac is absorbed, and then the tiny Parr* swim 

 freely ; and, passing the small rapids from box to box, reach the 

 lower canal, where they do not stay long, but voluntarily seek 

 the larger pond below by the streamlets. In the rearing-pond 

 they are fed chiefly on boiled liver, besides such food as they 

 can obtain amidst the water and water-plants. Next year, 

 * Parr are readily distinguished by the bold pigment-bars along the sides. 



