MANUAL OP FISH-CULTURE. 



49 



The water is fed into one end through a wooden or rubber tube 

 guarded by a wire screen, and is regulated by a simple swinging 

 gate. The outlet is either over a wooden dam or through a hollow 

 plug, either of which determines the height of the water in the trough^ 

 which is always maintained just at the top of the covering tray or an 

 eighth of an inch above it. 



Fi|.l. 



- ^ ' ' nttm i y i i i iir 



t ± 



Kg. 2 



- Trough Arranged for Eggs. 

 Fig. 1, plan. Fig. 2, longitudiiial section. 



o. supply -trough 

 b, screen. 

 d. supply-pijie. 

 /, egg-trough. 



J. down- spout. 



r, cleats. 



«, slacks of egg-trays. 



t, waste-pipe. 



«, screen. 



V, outlet. 



w, wooden dam. 



X, water surface. 



For the regular picking and cleaning, and for other examinations, the 

 stacks are removed from the trough to a table, where the trays can be 

 taken out one by one, set over into an empty frame, and returned to 

 the trough. This can be performed with ordinary caution at any stage 

 of the development of the embryo, without doing the slightest injury, 

 and after the delicate stage is passed the trays and their burden of 

 eggs can be washed at the same time in a pan of water. 



WINTER CARE OF EGGS. 



The eggs pass the wiuter in the stacks. They are regularly picked 

 over and the dead ones removed once or twice a week — twice during the 

 first few weeks, on account of the comparatively high temperature then 

 prevailing and the consequent rapid development of decay and growth 

 of fungus. It depends, to a considerable extent, on the water tempera- 

 ture; the water at the beginning of the spawning season varies from 

 50' to 55^ F., and maintains a mean of 43^ to 45^ F. during the month 

 of November. 



The color of a good egifx, or of an unimpregnated egg that still retains 

 its vitality, is a translucent salmon pink, with some variations in shade. 



r. U. R. 1897 4 



