ARTIFICIAL BREEDING OF SALMON. 205 



with water from the latter till they are both equal. 

 Great care must be taken not to hurry this operation. 



The contents of the box should then be emptied 

 into a good-sized tub half filled with water of the same 

 temperature as that in the hatching-case. By gently 

 moving the hand about among the moss, the ova will 

 sink to the bottom, and the moss remain floating on the 

 surface. The water should now be drained off, and the 

 ova at once deposited in the hatching-boxes. 



Should the water in the hatching-boxes, however, be 

 of a higher temperature than the moss in which 

 the ova were conveyed, these can be at once removed 

 into the hatching-cases after they have been detached 

 from the moss as above described. 



ON THE ENEMIES TO THE OVA AND YOUNG FISH. 



The greatest care must be taken to prevent the en- 

 trance of insects and larvae into the hatching apparatus. 



The most dangerous enemy to the ova and the young 

 fish is, perhaps, the water-newt (Sorex fodiens) . If the 

 apparatus cannot be raised to a sufficient height above 

 the ground, it should be protected with a perforated tin 

 or zinc lid. 



A curious instance occurred at the hatching esta- 

 blishment at Greffsen, a water-cure 'establishment 

 near Christiania, a few years ago. The apparatus was 



