74 MARVELS OF FISH LIFE 



red. As already described, it has no shell in the ordinary 

 sense of the term, but is covered with a strong, partly 

 elastic membrane, and if thrown upon a hard surface 

 it will bounce like a rubber ball. Salmon eggs possess 

 characteristics which, though they require certain con- 

 ditions in theu transfer, make it possible for them to 

 be sent all over the world. 



For twenty-four hours after the egg has been taken 

 from the fish, handling or a slight shock or jar does not 

 injure it, and it can be sent by rail either in or out of 

 water. After twenty-four hours, when the first stage of 

 visible development has begun, the egg becomes exceed- 

 ingly delicate, and the slightest jar will now kill it. 

 This susceptibility to a jar or shock continues until 

 about one-third of the incubation has been passed 

 through, and the extraordinary thing is that the eggs 

 which would certainly be killed by handling on one 

 day can be handled on the very next with impunity. 

 The expert fish culturist can tell when an egg can be 

 handled without the fear of injuring it by watching the 

 development of the tail of the future fish as seen 

 through the egg membrane. 



After this immunity to shock has been arrived at, 

 the egg can be packed for transport. 



The time of hatching varies in common with all 

 other fishes' eggs, according to the temperature of the 

 water. The colder the water, the longer is the hatching 

 delayed. It is by taking advantage of this fact that 

 long distance transport is possible. Eggs, which at the 



