16 



fish forces the eggs out. Fish caught m a trawl-net are 

 generally mixed up with a large quantity of debris, 

 especially after a four or five hours' drag, and the weight 

 of this " rubbish " pressing against the ripe fish forces the 

 eggs out before the net is emptied on deck. The majority 

 of the eggs that are brought in to our hatchery from 

 these expeditions, therefore, are not perfectly mature, 

 consequently the eggs may not be fertilized at all, or if 

 fertilized, die off before hatching out. It is from this 

 cause that the high mortality arises. 



An instance of this was demonstrated during the past 

 season. A large female Plaice, fully distended with eggs, 

 was brought in by the steamer from one of the expeditions, 

 and was kept alive in one of the tanks. In the course of 

 a few days however, it turned sickly, and to all appear- 

 ances was in a dying condition. The eggs were therefore 

 pressed out into a bucket containing a small quantity of 

 sea-water, and mixed with the milt of a male Plaice that 

 had been brought in along with the female. None of the 

 eggs floated, although examination showed a number of 

 them to have been fertilized, and to be undergoing develop- 

 ment. The living ones were carefully picked out and 

 placed in a jar by themselves. Notwithstanding a con- 

 siderable daily mortality, development proceeded rapidly, 

 and in a few days the little fishes were showing very 

 clearly through the egg membranes, but only two hatched 

 out. A number of the embryos reached the hatching- 

 out point and then died. The two that did hatch out were 

 feeble in their movements, and lay on their backs at the 

 bottom of the jar. They were very different from the 

 larvae of the Clyde Plaice, and only lived a few hours. 



It is clearly evident then, that fish eggs for hatcheries 

 must be under the most natural condition obtainable. 

 The only way to secure this is to collect the fish towards 



