55 



i^appenrcil, a healthy wcU-fcd fish which had traveUed more 



than 30 miles seaward in obedience to the migratory instinct, 



and it also proves to my mind that inasmuch as it could not 



be one of the fish originally hatched from an English salmon 



trout egg, and there liad not been sufficient time for the 



salmon trout to have bred and produced a smolt of that age ; 



. hat, therefore, that first smolt could only have been a true 



salmon — the whole difiiculty in the determination of its 



ipecics having arisen from the fact that, however valuable 



he _ tests api>lied may have been for the elucidation of the 



[tecies of adult specimens, those tests are valueless when. 



ppliod to immature fish. So with the determination, of the 



icond gi'ilse. If we are to regard it as adult, — that is to say, 



' it has arrived at such a stage that there would be no 



irthcr change in the anatomical details of the fish on its 



'xt journey seawards, beyond mere increase of size, — then 



le tests applied by Dr. Giinther would doubtless be sufficient 



' warrant the conclusion that it is a salmon trout {Salmo 



titta) ; but if, on the other hand, any further change 



ight take place in those details, its species cannot with 



•solute certainty be determined till the sum of that change 



■s been recorded ; and, therefore, nothing but the capture 



a full-grown specimen will ever satisfactorily set the 



■ jole question at rest. 



