152 REPORT OF COMMISSIONER OP FISH AND FISHERIES. 



tlius expelling all the air from the feed-tube ; otherwise it would rise 

 in bubbles, throwing a portion of the eggs out through the outlet-tube. 



With a proper quantity of semi-buoyant eggs in the jar and the 

 water turned on and regulated, the movement of the current estab- 

 lishes a regular boiling motion in the mass of eggs, which brings each 

 m succession to the surface. This motion may be regulated without 

 altering the quantity of water. By loosening the upper binding-screw 

 of the central stufiSng-box, and pushing the feed-tube down until it 

 almost comes in contact with the bottom of the jar, the motion of the 

 eggs is increased. If the jar is working properly, the dead eggs when 

 brought to the surface remain on top, forming a distinct layer, and by 

 pushing down the outlet tube a suitable distance they are lifted up 

 by the escaping current and taken out. 



When the water is turned on for the first time the jar should be 

 watched closely until a regular motion has been established. When 

 eggs have stood 15 or 20 minutes in the jar before the water is turned 

 on they do not readily yield to the boiling motion, but tend to rise in a 

 solid mass to the top of the jar. By quickly starting and stopping the 

 current the mass is readily disintegrated. The degree or intensity of 

 motion of the eggs varies not only with their age and condition, but also 

 with the condition of the water. If the water is muddy, the motion 

 should be rapid enough to prevent mud settling either on the eggs or in 

 the bottom of the jar. Ordinarily the best motion is that which readily 

 brings the dead eggs to the surface. After the hatching has progressed 

 far enough to dispose of a portion of the eggs there is less resistance to 

 the current, and it should be reduced by shutting off part of the supply 

 or by slightly lifting the central tube. If the motion is not reduced 

 from time to time as the hatching progresses, shells will be carried over 

 into the receiving-tank with the fish and, being very light, will be drawn 

 against the outlet screen, causing an overflow. The motion should be 

 so gentle at the time of the greatest hatching as barely to induce the fish 

 to swim out of the jar and leave their cast-ofi" shells behind. 



Very healthy egga, exposed to bright direct sunshine, hatch so rapidly 

 that the combined effort of the swarming mass of young fish will 

 establish sufficient current to draw some shells over into the receiving- 

 tank. This may be modified by placing a screen between the jar and 

 the light. The shells under normal conditions remain and form a 

 cloud-like layer above the mass of working eggs. As they accumulate 

 they should be removed by shoving down the outlet-tube until they are 

 drawn up with the escaping water. A good plan is to draw several 

 jars in succession into a large pan, whence any fish coming over with 

 the shells may be ladled into the receiving- tank. 



A remnant of eggs may be long in hatching, and they should be 

 poured into a large, clean, bright pan and exposed to bright sunlight, 

 when they will hatch in five or ten minutes. 



If the connection of the jar must be broken, it is essential that tlie 

 rubber feed- tube does not drop down and siphon the eggs from the jar. 



