MARINE FISH HATCHERY AT FLODEVIG, NORWAY. 



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etc., pollute the bottom layer of the water. To prevent the spawners from 

 coming in contact with this the pond is provided with a wooden flooring, 

 about I foot over and above the highest part of the bottom, and with a 



Fig. 2. — Spawning pond. (Plan.) 



Space between the boards of about i}4 inches. Through these openings the 

 impurities will sink down into a sort of funnel-shaped cellars, provided with 



Zrr^/ a. 



Fig. 3. — Same as figure 2, showing section A-B. 



4-inch drainpipes in their lowest part. (Fig. 2 and 3.) These drains 

 are opened about a quarter of an hour every day. In spite of these precau- 

 tions, however, the bottom water will, after a time, be contaminated to a 



