NATURAL HISTORY OF THE SALMON. 57 



season theory lies with the late Mr, W. Paulin of 

 Berwick) ; but giving proper weight to the consideration 

 that most of the ascertained facts, as distinguished from 

 the disputable ones, go to support the second-season 

 theory, that side has perhaps a present advantage in 

 the controversy. The actual evidence in favour of the 

 second-season view might be supplemented by arguing 

 that, as a grilse weighs more pounds than a smolt does 

 ounces, or, in other words, has increased in weight about 

 twentyfold, it is more rational to suppose that that great 

 change took place in fifteen than in three months ; but 

 even the keenest partisan of the second-season theory 

 ought to forego that advantage, it being desirable ia such 

 questions to proceed only upon what has been seen or 

 ascertained, not on what may be only reasonably con- 

 jectured or even logically inferred. 



On the other hand, there is one fact afibrding 

 a very strong presumption in favour of the same- 

 season theorists, which we put separately, because the 

 fact, though quite unquestioned, does not amount to 

 actual demonstration on the point in dispute. Grilses 

 invariably ascend two or three months after the smolts 

 of that season have descended ; or, to state it in an- 

 other form, there are no grilse until the smolts have 

 been some time departed. Now, if grilse have been a 

 preceding winter and summer in the sea, why should 

 the time of their ascent bear so rigidly fixed a relation 

 to the time of the descent of the smolts, when we find 

 that the adult salmon, which is, or has always been held 

 to be, the same fish one year older, makes its ascent in 

 some proportion in every month of the twelve ? 



