64 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



off.- But the most careful manipulation will fail to prevent tlie escape 

 of many good eggs with the bad ones when this plan is pursued, as the 

 line of separation between the two is not distinctly drawn. 



I have found that a great saving of time, as well as eggs, can be effected 

 by using a glass siphon to draw off the surface eggs. I have also used 

 the siphon very successfully while operating the cone in shad hatching. 

 No nicety need be observed in this process, as all eggs thus separated 

 can be placed in a separate jar, when, in a few moments, a solid layer 

 of eggs of confervoid growth will collect on top and can be readily 

 siphoned away unattended with the loss of any good eggs, while the 

 latter can remain in the jar to be manipulated as before when necessary. 

 Other ways of assisting the jars to eliminate the extraneous eggs have 

 been tried, but I have found the siphon plan to be by far the most ex- 

 peditious and need not result in the loss of a single good egg by throw- 

 ing away. This plan, then, consists essentially in collecting the surface 

 eggs from the jars as often as may be necessary or desirable and con- 

 densing the same into one or more jars, from whence the most of the 

 dead eggs can be removed without disturbing the good ones ; by thus 

 completing, with the aid of the siphon, the n^itural operations of the jar 

 in separating the bad eggs from the good ones, the tedious and expensive 

 process of picking out the dead eggs with nippers is done away with. 



In any method of incubating eggs wherein they are stationary, as^ 

 with the hatching boxes and trays, a slimy coating will be found adher- 

 ing to the eggs which must be washed away as often as may be neces- 

 sary; and for the same reason, the trays, boxes, and troughs also will 

 require an occasional cleaning. And again, when the eggs are hatching^ 

 the trays require a daily manij)ulation to dislodge a portion of the fry 

 and shells which will not escape through the meshes. All this work 

 is unnecessary when the jar is used ; the constant motion imijarted to 

 the eggs by the current of water keeps them bright and clean, and when 

 hatching the fry and shells are, by the upward current, drawn out 

 through the mouth of the jar into a tank for their reception, the gate at 

 the mouth of the jar being removed during the hatching season. 



The following suggestions may be of service in operating the jar :^ 



It should be full of water, and, with its accessories, in position and 

 in running order before the introduction of the eggs ; but, while they are 

 being introduced, it is better to interrupt the water supply of the jar 

 being filled, which will prevent the eggs frdm flowing^ against and clog- 

 ging the wire gate. 



The rubber connecting-pipe should extend down inside the glass tube 

 below the levfel of the water in the jar, to keep the water free from air- 

 bubbles. 



Eggs are sometimes found bunched together on their arrival from the 

 spawning grounds; these should be broken up before their entrance 

 into the jar, as the movement of the water therein is too gentle to accom- 

 Ijlish this end. 



