HATCHING APPARATUS. 6j 



strips, and sinking down through the apertures out 

 of the way. 



Wire-netting Hatching Trays. 



When the foregoing part of this chapter was writ- 

 ten in 1872, wire trays were not used to much extent 

 for hatching the eggs of fish. At the present writing, 

 in 1877, wire trays are very extensively employed, and 

 it seems likely that their use will entirely supersede 

 the old method of hatching on the bottom of the 

 hatching troughs and on glass grilles. 



The trays in question consist simply of a light 

 wooden frame made perhaps of three-fourths inch 

 stuff, with a wire-netting bottom, or, in the case of 

 deep trays, wire-netting sides also. The trays are 

 made a little narrower than the troughs, and of any 

 convenient length, from a foot to eighteen inches, 

 or two feet. They are coated all over twice with 

 asphaltum varnish, to keep the wood part from grow- 

 ing fungus and the iron part from rusting. 



They are usually placed on a rack, to raise them 

 an inch or two from the bottom, and the whole bot- 

 tom of the trough covered with them, the end of one 

 adjoining the end of the next, and so on. If desir- 

 able, another tier can be similarly placed on top of 

 these, and another, and another ; as many tiers being 

 laid as the water supply and circulation will warrant. 

 They can be used in various other ways, as will be seen 

 further on. 



The advantages of the tray system are very great, 

 the chief merits about it being that it economizes 



