MANUAL OF FISH-CULTUKE. 25 



iron wire, with meshes | by i of an inch, fastened at the top to a wooden 

 frame i inch thick. They are '23 inches lonj?, 15i inches wide at top, 

 15 inches at bottom, and G inches deep. When placed in the hatching- 

 trough the wooden frame of the basket rests on the edge of the trough. 



Two division phites of galvanized iron are i)laced in the hatching- 

 trough just above each basket. The first one rests on the bottom 

 and extends to within an inch of the surface of the water; the second is 

 placed half an inch below the first one, and extends from the top of the 

 box to within an inch of the bottom. Tliis causes an upward current of 

 water to pass through the eggs, which, however, is not strong enough 

 to move them. 



From the second to the tenth day the eggs are washed and the dead 

 eggs are picked out, but from the tenth to the fifteenth day they are 

 not handled in any manner, no matter how much sediment may cover 

 them. After the fifteenth day, or when the young fish is well defined 

 in the egg, washing and picking is renewed and continued daily until 

 the eggs are packed for shipment. 



The method of handling is determined by the conditions, a lower 

 temperature allowing them to be washed beyond the tenth day, but 

 the above noted is the average for the season of 1896. The total loss 

 in ej^eing (that is, carrying eggs from time of taking until the eye- 

 spots appear) during the season was 1,308,290, or 5.06 per cent. No 

 eggs were hatched at Battle Creek station, as the water supply was 

 considered unsafe. 



In packing eggs for shipment no ice is used except for long distances. 



The eggs received at the Sisson station of the California Fish Com- 

 mission, located at the headwaters of the Sacramento River, are treated 

 by methods similar to those already described as being used at Battle 

 Creek. The average number of days taken to hatch the eggs is 42, 

 and the alevins absorb the sac in from 30 to 40 days at an average 

 temperature of 44°. After the eggs are hatched, the division plates 

 resting upon the bottom of each trough are removed and the remaining 

 plates lowered to within half an inch of the bottom of the hatching- 

 trough. This divides the trough into sections and results in a stiff" 

 current running under each plate, which prevents the massing of the 

 alevins at the head of the trough. At this time, a A-shaped piece of 

 galvanized iron, termed a harbor plate, is placed in each trough 4 inches 

 above the retaining- screen, with its apex against the current; it extends 

 to within an inch of each side of the trough and rises to the surface of 

 tlie water. The water in passing around each end of the plate causes 

 an eddy that carries the weak alevins away from the screen into the 

 angle of the plate, affording them a harbor of rest and preventing their 

 being held against the screen. 



The loss of alevins while absorbing the sac is slight. The space for 

 hatching-troughs at Sisson is limited; and to relieve the troughs tlie 

 idauting of alevins begins a few days after they hatch} hence the exact 



