50 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



It is possible, by placing it iu a favorable light, to get a fairly good 

 interior view, including tlie detailed anatomy of the embryo. When 

 the egg dies it turns chalky white, becomes wholly opaque, and in a few 

 days, depending on the temperature, decay sets in, and sometimes a 

 white water-mold or fungus begins to grow upon it. The mere decay 

 of the egg would foul the water, thereby injuring the neighboring egga, 

 and the fungus established on the dead eggs may spread to the living 

 ones. It is therefore essential that the white eggs be removed before 

 they have time to do any injury. 



For egg-picking a homemade pair of tweezers, about 6 inches long, is 

 used, made of any convenient wood and tipped with a pair of wire 

 loops of a size to conveniently grasp the egg. The operator lifts the 

 stack of trays carefully from the trough and, to save dripping, carries 

 it on a wooden waiter to a well-lighted table of convenient height, on 

 which stands an oblong pan, 14 by 18 inches, holding about an inch of 

 water. 



The stack of eggs to be picked is placed at one end of the pan and 

 at the other end is an empty stack-frame. The trays are examined one 

 by one, dipped in the pan of water, picked (or cleaned by agitation 

 when the eggs are in condition to endure the disturbance), and j)laced 

 in the empty frame. The air of the room is kept at a low temperature 

 during this process, and the water m the pan is often changed. 



The eggs when first impregnated are very sensitive to rude shocks and 

 are handled with great care. Within a few hours the germ begins to 

 develop; iu 10 days, at a temperature of about 40° F., the germ-disk 

 appears as a ring of color on the upper side of the yolk. At this date 

 the unimpregnated egg presents the same appearance and does not 

 change much until its death, however long that may be deferred. In 

 the impregnated egg, however, the germ-disk continually enlarges upon 

 the surface of the yolk ; the ring of color that marks its edge advances 

 before it, passing quite round the yolk, and closing up on the posterior 

 side. 



As early as the thirteenth day the difference between the imx^regnated 

 and unimpregnated egg is quite plain to the unaided eye after a very 

 little experience, and three or four days later the good egg is marked 

 by a distinct line of color passing around the very middle of the yolk, 

 a phenomenon never appearing in an unimpregnated egg. During 

 this stage, while the embryonic disk is spreading around the yolk, 

 the egg grows constantly more and more delicate, and liable to rupture 

 of its tissues and consequent death on very slight disturbance; but 

 later the tissues grow stronger, and when, about the thirty-fifth or 

 fortieth day, the eyes of the embryo have assumed enough color to 

 appear as two dark dots, the egg has attained hardiness enough to 

 endure rougher handling. Thenceforward, until the near approach of 

 the time for hatching, the work consists simply iu i^icking out the dead 

 ones, occasionally rinsing out the sediment, and sometimes removing 

 the unimpregnated eggs. 



