82 



MR. r. DAT ON THE LOCH-LETEN TROUT. 



spots. As the water in the two localities was the same, food would 

 seem to have beeu the principal reason of this change in colour. 



Although the last experiment does not prove very much, it 

 show^s that some alteration in colour may follow new environ- 

 ments ; but a still more conclusive result as to the change in colour 

 which may take place in these fish under like circumstances has 

 lately occurred in Gloucestershire. The present proprietor of 

 Cowley had two ponds in a wood on his estate, each about an 

 acre in extent, and from the lower of which springs a small 

 stream ; these he washed to have stocked with some good kinds 

 of sporting fish. The two ponds are supplied by underground 

 springs, while there is a fall of about 16 feet from the outlet of 

 the upper pond, and a rather greater one from that of the lower 

 where the stream commences. It will thus be apparent that no 

 fish could obtain access from above, neither could they ascend 

 the 16-feet perpendicular fall from the stream to the lower pond. 

 It was determined to try the Loch-Leven trout; so these ponds 

 were drained, mudded, and then puddled with clay. 



During December 1884 and January 1885 one thousand yearling 

 Loch-Leven trout were received from Mr. Andrews of Guildford*, 

 and these were placed in the ponds by Mr. Ogden, of Cheltenham. 

 In August this year (188G)I was informed that, it having become 

 necessary to remove these fish to a more suitable locality, they 

 had been capturing them, and very great diff'erences were percep- 

 tible both in size and colour among the two sets of fish — those 

 in the upper pond being silvery with a few black spots, whereas 

 those in the lower pond were of a much larger size, covered with 

 spots, and having purple and golden reflections. Having obtained 

 leave, we visited these ponds on August 25, and first examined 

 the temperature of the water by means of thermometers, when 

 we found that they scarcely differed. The lower pond was the 

 deeper, and in it were large quantities of the American weed, 

 Anacharis Alsinastrum, also some Cliara, while on the surface 

 was a considerable amount of the water crowsfoot {Ranun- 

 culus aquatUis)\ whereas in the upper pond there were fewer 

 weeds, but some Fiwpinella Saxifraga was present near its upper 

 end. 



* Mr. Andrews, of West gate House, Guildford, wrote (September 14, 1886): — 

 " The yearling fish supplied to Mr. Ogden, of Cheltenham, in 1885, were Loch- 

 levens reared from eggs which were sent me from Howietoun. There can be 

 no doubt of their being from ova from Stirling, as they were put in a pond 

 quite distinct from the others on a different water-shed." 



