196 THE SEA-TROUT 



known percentage of loss, but one may expect more barren eggs from 

 an old fish than from one in the prime of life. Of the 2,080 eggs shed 

 by the fish described on page 73, only 10 were found to be dead or 

 barren after two days. But from one cause or another, during the 

 whole period of incubation an egg here and there will be found opaque 

 and whitish when it should at once be. destroyed. With careful manage- 

 ment the loss in eggs is wholly negligible. 



With ordinary care the eggs will duly hatch out at the appointed time 

 when the young fish, or alevins, appear on the scene. 



I do not propose to reiterate the description of the alevin formerly 

 given, but some points in hatchery management must be referred to. 



In those boxes containing grilles it will be observed that, as the 

 eggs hatch, the alevins drop through between the glass tubes to the 

 bottom of the box, and the syphon tube will now be in constant use 

 removing the empty shells. When the eggs are all hatched, the glass 

 grilles, and the frames which carry them, and the longitudinal runners 

 on which the frames rest, are removed, thoroughly cleaned, and care- 

 fully put away. The hatching box has now become a small rearing 

 pond in which the alevins live comfortably until they reach the " fry " 

 stage. Before they leave the hatching box for the outer world, even 

 before the umbilical sac is wholly absorbed, they may be seen all lying 

 head upstream to the inflowing water, and " rising " now and then 

 inquisitively to some tiny floating speck. As with the grille boxes so 

 with the basket boxes. When all the eggs are hatched, the baskets and 

 supporting runners are taken out, cleaned, and put away safelv. It is 

 convenient to keep all the alevins of one mass of ova in their own basket 

 till the whole box has hatched out. 



During the period of absorption of the umbilical sac, at least in the 

 earlier stages, the instinct of the alevin, which can only wriggle 

 spasmodically on its side, drives it to hide in any minute crevice that it 

 can find. Now it is, therefore, that previous careful smoothing of all 



