4791 Fishes. 



remains unexplained, and without a counterpart in zoology, namely, 

 that the male salmon of five or six months age, according to the 

 Invershin hypothesis, and of seventeen or eighteen months age, 

 agreeable to the Drumlanrig experimenter, should already have 

 arrived at the adult condition in respect of the ability of reproducing 

 his kind ; the female in the meantime continuing, as regards the 

 ovaria, at the minimum of development; and, as if to add to the com- 

 plexity of the enigma, we are now further asked by these experi- 

 menters to believe, that the female, in whom the ovaria do not alter, 

 grows faster than the male by a whole year, the generative organs and 

 the general growth of the body being in an inverse ratio to each other. 



6. The May smolts, covered with scales, collect into flocks or 

 groups, and descend the rivers to the ocean ; parrs never do. In the 

 smolt which descends to the ocean in May to seek a habitat still un- 

 known, the ovaria and milt are uniformly at their minimum. His 

 food in the ocean was unknown until I demonstrated it to be the 

 eggs of the Echinodermata. The smolt which descends to the 

 ocean in May, 5 or 6 ounces in weight, returns in July, August and 

 September a grilse or salmon of as many pounds. If permitted, he 

 returns to the ocean next spring; he again makes for the rivers a 

 grown salmon in the autumn of the same year, varying from 12 to 

 20 lbs. weight. His subsequent history is not well known. 



Lastly : Whilst in the fresh waters the grown salmon does not feed, 

 but loses condition to a great extent : thus a return to the ocean is 

 essential to his existence. Whilst a smolt he lived and throve on the 

 common food of trout; he acquires the silvery scales in May, being 

 then 7 or 8 inches in length ; he seeks the ocean, impelled by an in- 

 stinct seemingly as strong as that which induces the grown salmon to 

 rush up the rivers at the approach of winter. 



The observations just made are generally admitted to be facts: the 

 more curious, indeed all of any moment, were known to Willoughby, 

 Hutchinson and others; but they do not solve the difficulties con- 

 nected with the subject, the first of which is — What is the age of the 

 May smolt? 



What is the aye of the May Smolt ? 

 The opinion which has prevailed, in Annandale, time out of miud, 

 is, that as the parr is the young of the salmon, so the May smolt must 

 be one or two years old ; some thought more. The practical fisher- 

 men of the Tweed thought otherwise; they disbelieved the parr to be 

 tho young of the salmon, and thought that the May smolt was the 



