APPENDIX. 237 



of the trout, a strong, well-shaped fish, though somewhat 

 dark in color, and of two pounds' weight. We also caught 

 specimens of the fish in the other lakes, and the difference 

 between the fish I have already mentioned. While fishing 

 the small lake I accidentally allowed my fly to sink to the 

 bottom, and on pulling it up again with some difficulty I 

 brought up a large piece of a thick moss-like green weed, 

 with which the bottom of the pool appeared to abound. 

 On examining this weed more closely, I found it swarming 

 with a variety of insects, chiefly water-snails, the small 

 Crustacea that inhabit fresh water, and large quantities 

 of the caddis of some considerable fly. The abundance of 

 food thus found at the bottom of the lake fully accounted 

 not only for the large size and good condition of the fish, 

 but also for its being a sulky lake, or for the trout not pay- 

 ing much attention to the flies upon the surface of the 

 water. For they had no difficulty in procuring any quan- 

 tity of food they needed at the bottom, without swimming 

 hither and thither to seek it, or giving themselves the 

 trouble to come to the top. Colonel Whyte also mentioned 

 a fact somewhat of this nature, some time since, in the 

 ' Field.' He related, that wishing to improve the size and 

 condition of his fish in a small lake, he cast into it a bushel 

 of the small Crustacea, which are often found on water- 

 weeds. These increased rapidily, and as they did so his 

 trout increased in size and improved in condition wonder- 

 fully; but it is also fair to say, that they became much 

 shyer of rising to the fly. Probably the reason why the 

 fish Sometimes rise well to flies, and not at others, in lakes 

 like those of Donegal (which are by no means few), is 

 owing to the fact that the abundance of caddis at the bot- 

 tom may be undergoing some transformation, into flies per- 

 haps, which ascend rapidly to the top of the water, and the 

 trout are thus led in pursuit of them to the top of the water, 



