DR DAVY ON THE SALMONLD^. 249 



this, they had never, they said, found the ova.. — which, indeed, is not surprising 

 considering the great extent of the lake, and that they had never made search 

 for them. 



The only instance I can mention as appearing to be well authenticated, of a 

 salmon spawning in a lake, I learned from an old Irish fisherman residing in the 

 neighbourhood of Lough Erne. He assured me that he had seen a pair of salmon 

 preparing their spawning-bed in a shoal of the lake off an islet known by the 

 name of Rabbit Island. 



If what I have stated should be received as satisfactory, I hope it may prove 

 not without use, as tending to show that the Salmonidse may be bred in lakes 

 and ponds ; and thus encourage attention to these as breeding places, — for in- 

 stance, in ponds, by providing beds of gravel, and in lakes, where fish are known 

 to spawn, by affording protection from the depredation of the poacher, which, in 

 the instance of the charr, we know, from experience, to be much needed in some 

 of our Westmoreland lakes. 



4. Of the Variable Time of the Hatching of the Ova. 



In a paper already referred to, that " On the impregnation of the ova of the 

 Salmonidae," mention is made of the successful result of impregnation in the in- 

 stance of the mixing together of the roe and liquid milt of the charr obtained 

 from the living fish. 



The roe, after having been thus brought into contact with the milt, was divided 

 into three portions. One, the largest, was placed in an earthenware pan, about 

 two feet in diameter, in which was a stratum of gravel taken from an adjoining 

 brook, and water, soft spring water, to the depth of about three inches, which 

 for the most part, about two-thirds, was changed daily. The ova were laid on 

 the gravel, and the vessel was placed on the floor of a room without a fire, where 

 the temperature was liable to little fluctuation. 



Smaller portions were put into two water or finger-glasses, such as are used 

 at table, about four inches in diameter, in which also gravel of the same kind 

 was laid, with water from the same spring to the depth of about two inches, and 

 which, as in the first mentioned, was in great part changed daily. Both glasses 

 were placed on a stand about three feet from the ground, and within a few feet 

 of the pan, and all three were exposed to about the same degree of light. 



The experiments were commenced on the 25th of November. On the 8th of 

 January, in each of the glasses, three young fish were found in the morning at 

 large, excluded during the preceding night. On the 9th, more had made their 

 appearance in the upper vessels, but none in the one below. The temperature of 

 the water in the glasses was 50° Fahr., that of the water in the pan on the floor 

 being 48°. On the 10th, many more young fish were produced in the glasses, but 

 one ovum only was found hatched in the pan. On the 13th, whilst no more had 



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