INTRODUCTORY 27 



of the Hebrides, where the streams are so trifling, or elsewhere in the 

 Highlands, where the streams are such barren, rocky, mountain torrents, 

 that there is neither security nor sustenance for trout in them. 



It is rather corroborative of this view than inimical to it, that trout 

 are to be found, as Mr. Calderwood found them, in the estuary of the 

 great river Tay. The fact merely proves that even in such rich streams 

 some trout will so descend to the sea. In the estuary of the Clyde, 

 below the junction of the river Leven with it, such trout have frequently 

 been captured in the salmon nets. I take it that these fish had 

 gradually dropped down stream from the upper reaches of the Leven, 

 or perhaps even from Loch Lomond, because I am informed by a local 

 boatman, of whose capabilities of judging I have personal knowledge, 

 that on one occasion he caught with rod and line in the loch a trout 

 which had tide-lice on it. I give this incident for what it may be 

 considered worth, for it suggests not only that a trout had descended 

 to salt water but that it had returned to fresh water again, as such trout 

 must do if they propose to spawn. 



If it is objected that in all this I am only stating grounds for the 

 belief that estuarine trout are really ordinary non-migratory trout that 

 have become more or less migratory, it may be recalled that this is the 

 particular point in Mr. Regan's thesis that is at the moment under 

 discussion. But to revert now to the main argument, I shall simply 

 confine myself to the suggestion that, having regard to the foregoing 

 facts, the offspring of these enterprising trout, given favourable circum- 

 stances, may easily become indistinguishable from migratory sea-trout, 

 though this savours not a little of taking matters for granted. The 

 suggestion, however, leads naturally to the discussion of Mr. Regan's 

 sixth, and perhaps most interesting, proposition, which I shall now 

 submit. 



