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however, as to what amount of brackish water will destroy it; 
and, as we have a lot of spawning fish depositing their ova in 
the stream, just below Ruswark Mill dam, over which they 
cannot get when heavy in spawu, and up to which spring tides 
rise about two or three feet, covering the spawn beds for about 
two hours each tide for some three or four days at each period 
of high tides. Some ova from fish spawning there was pro- 
cured and placed in a box in the gravel at that spot. This was 
done in order to ascertain whether it would come to life. 
Though nothing came of the experiment for the first two years, 
it was found that this year a good portion of it was hatched, 
thus showing that it was not all killed by salt water. Another 
account states that some of the ova were removed from this 
box, and hatched in a basin of fresh water in the village brook, 
whereas all that were left in the box died. 
Sir J. Marueson, during the winter of 1861-62, had two 
portions of impregnated salmon eggs used, one for trial in 
brackish water of specific gravity 1,015, the other in fresh. 
They were held on a wire cloth in a glass vase with a tap at its 
bottom, and the water was changed daily. During the first ten 
days the ova in the brackish water did not appear to suffer, and 
no longer; no foetal development was observed in them, and 
they all died, while those in the fresh water made progress, and 
in due time were hatched. 
Dr. Davy tried the effects of a solution of common salt 
in water, having a specific gravity of 1:026° on a salmon egg, 
the embryo in which appears to have succumbed in a few hours 
over two days. The ovum of a Dee salmon in similar water, 
of a specific gravity of 1:007° was hatched at the end of about 
forty-eight hours ; the young was very languid, but at the end 
of the fourth day was still alive. 
Brown, in his account of the Stormontfield experiments, 
observed :—‘* We have also taken ova which had been recently 
manipulated upon, and dropped it into sea water, which destroyed 
it almost instantaneously, only a few of them becoming opaque; 
in the greater portion of them the yolk became shrivelled up 
and contracted.” 
foe 
