HATCHING APPARATUS. 63 



vigorous-looking embryos that are sure to develop in 

 the dark. At all events, my experience has been 

 decidedly to the effect that eggs hatched in the dark 

 develop a thicker, firmer, and harder fish than those 

 hatched in the light ; and the first three months of 

 feeding proves it. I am sure, at least, that no young 

 trout fry could be hardier or healthier than mine have 

 been through their first six months, and all of mine 

 are hatched in covered hatching troughs. 



But even if darkness were not desirable, there is 

 another reason of the utmost importance for having 

 covers on the troughs. It is that you are not certain 

 that your eggs are safe a single night in the open 

 troughs. The enemies of trout eggs are legion. 

 Mice, snakes, lizards, rats, weasels, and you know not 

 what else, may be feeding on the eggs every night if 

 they are not covered. I lost thousands of eggs and 

 alevin trout in this way, before I began to use covers. 

 At the Mirimichi Works, we lost at least twenty thou- 

 sand salmon eggs, in the course of two weeks, by a 

 weasel, before we began to suspect danger. There is 

 no security without covers, at least in ordinary hatching- 

 houses. On the contrary, when the covers are on 

 and down tight, then, and only then, you know you are 

 safe. And this is the only normal condition that any 

 department of a trout-breeding establishment should 

 ever be in. 



The covers, for convenience' sake, should be made as 

 light as possible. Half-inch pine, and even thinner, 

 answers very well. There should be a piece cut out 

 at the upper end to let in the water, and wire netting 



