62 DOMESTICATED TROUT. 



away by itself. It is therefore a good plan to have 

 four barrels or large boxes in the hatching house, — 

 one for coarse gravel not clean, and one for fine gravel 

 not clean, one for clean coarse gravel, and one for 

 clean fine gravel. These boxes should be distinctly 

 labelled, so that clean and dirty gravel will not get 

 mixed ; and in course of time this little systematizing 

 of the gravel will be found to be a source of great 

 convenience, and economy also. A bushel of prepared 

 gravel usually costs more than a bushel of grain. 



When the gravel is laid in the troughs and the 

 water is turned on, they are ready for use, with one 

 exception, viz., — 



The Covers. 



I am firmly convinced that hatching troughs should 

 be covered. I would not have one without a cover. 

 Trout eggs and salmon fry are stronger and healthier 

 for being hatched in the dark. It is more natural 

 also. The foetus, or embryo, of almost every creature — 

 beast, bird, or fish, everything above insect life — is 

 developed in the dark. The embryo of the trout is 

 no exception to the rule. After the parent trout has 

 deposited its eggs in the bed of the brook, the gravel 

 with which they are covered, the stratum of water 

 above the gravel, and the layer of ice and snow above 

 the water, make it as dark, where the eggs are, as it is 

 in the covered hatching-troughs. 



Furthermore, the light seems to have a forcing 

 effect on the eggs ; and those that I have seen matured 

 in the light did not contain the dark, thick, firm, 



