MANUAL OF FISH-CULTURE. 207 



a glaas graduate. The dead eggs quickly sink and the quantity, in 

 ounces, is noted on a card attached to each box. If there are any good 

 eggs in the glass they are saved; the spoiled eggs are thrown into the 

 waste-trough. Both the inner box and the trough in which it rests are 

 thoroughly washed an(Lsponged after each change. 



When the inner box is replaced it is made ready for the eggs to be 

 transferred from the third box, and the same method is pursued until 

 all the boxes have been cleaned. Eggs recently taken, being on the 

 surface, run over very quickly, 5 or 10 minutes usually suificing for 

 the transfer of a box of 400,000 eggs; but when eggs become heavier, 

 as a result of development, the cleaning takes much longer, as it is then 

 necessary to run them into the lower part of the box (as in removing 

 dead eggs) and to dip them out, care being taken to keep the lower 

 end of the box in the water while manipulating them. As the loss of 

 eggs has ceased by the time they reach this stage, everything in the 

 box may be dipped over, and with care no damage is done the eggs. 



THE FRY. 



When the fry first hatch they are much curved in shape and show 

 but little vigor. If the water is comparatively warm they rapidly 

 straighten out and become stronger. At this stage they float at the sur- 

 face, except when forced about by the current. As they get older they 

 frequent the upper water less and if kept in the boxes till the mouth 

 begins to functionate most of them remain on or near the bottom. 



As soon as the first fry in a given box make their appearance the 

 eggs are all runrover for the last time. As the fry are comparatively 

 delicate they are handled as little as possible and with great care. 



The fry are planted as soon as practicable. If all the eggs of a given 

 lot have not hatched it is better to plant them with the fry rather than 

 hold the latter until incubation is complete, for the boxes soon become 

 foul from the accumulation of eggshells and the eggs will haitcii in a 

 very s^iort time, especially as the water on the spawning-grounds is 

 usually 3 or 4 degrees warmer than the water in the hatchery. 



When the fry are to be removed from the boxes, preparatory to plant- 

 ing, a plug is i)ut in the current hole at the back of the box, and in a 

 short time most of them will come to the surface. They are then dipped 

 onit and put in transportation cans. About 200,000 fry may be safely 

 carried in a lOgallon can. Deposits are usually made on the natural 

 spawning-grounds. 



