198 SPORT IN NORWAY. 
width of the case by means of two pieces of wood, 
which are fastened to the sides, and reach nearly to 
the middle, and is carried off by a pipe. 
The slimy deposit which comes even from the purest 
water, and settles on the eggs (it is not detrimental 
unless there be too much of it), can easily be got rid of 
by gently moving the boxes, and allowing it to pass 
through the ends. 
After the lapse of about four weeks it will be well to 
take the hatching-boxes out of the case to ascertain 
which eggs are good. The action of the air will render 
them all transparent ; but on replacing them in the 
water, the unfruitful ones will assume a milky opaque 
colour. These can readily be removed with a pair of 
fine pincers or long tweezers. The exposure to the 
air does not hurt the eggs, but care must be taken 
that they do not become dry on the surface. After 
repeating this process three or four times, all the bad 
egos can be removed. “I am convinced,” is the 
remark of Professor Rasch, “that in a case of the 
above size I could hatch 10,000 salmon ova in each 
box, which would thus give a total of 160,000,” there 
being four hatching-boxes in each of the four compart- 
ments. If the fry are to be kept any time in the boxes, 
care must be taken that they be not overstocked ; but 
3,000 may well be kept in them from two to three 
months.” 
