On the growth of the salmon, from the egg to the adult / by R. Knox.

  • Knox, Robert, 1791-1862.
Date:
[1855]
Catalogue details

Licence: Public Domain Mark

Credit: On the growth of the salmon, from the egg to the adult / by R. Knox. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    seldom seen by the angler, and after which it ceases to be found in fresh-water rivers. Secondly, proof that the fish we call salmon fry (smolts), taken in salmon rivers by anglers during the months of April and May, do really proceed to the ocean, and return after a period to the rivers as grilse, salmon trout, and salmon. The facts ascertained by Dr. Knox, in conjunction with the previous observations of others who have attended to the subject, go towards the answer of the first question, whilst the experiments made in Sutherlandshire, on the Lax- ford and Divard may be considered as a reply to the second. Fry marked in April returned as grilse on the 25th June. Soon after these observations had been made and submitted to the Royal Society of Edinburgh, others entered on the field, and the Duke of Buccleugh must have taken some interest in the matter, since he permitted one of his game-keepers, a Mr. Shaw, to experiment on the ova of the salmon, and on what he called tjje parr. The ideas of this person respecting the parr have no foundation whatever either in observation or experiment; the experiments he made led to what is called the two-years' theory of the May smolt. By confining the young of the salmon in ponds and boxes, and placing them under artificial circumstances, he contrived to retard the growth of the fiy to the extent specified: thus he first misled himself, and then others. When I first heard of the two years' theory of the age of the May smolt, my remark was this— Wait a little, and another experi- menter, proceeding on the same principles or want of principle, will prove to you that three years is the age; and after a little while another of the same class will show you that one year is the true period. The prediction was verified to the letter. Mr. Hannay, of Kircudbright,* showed by experiment that the smolt is a three years' old fish; Mr. Young, of Invershin, by the same method, proves one year to be the true age, and the experiment repeated at this moment by my esteemed friend Dr. Esdaile, of Perth, on ova reared in ponds adjoining the Tay, has brought to a sudden close, and for ever, the two-year' old theory, a delusion of the plainest character, but yet sufficient to mislead many naturalists. Scientific continental natural- ists, finding persons engaging in these controversies who are not scientific men in any sense of the term, stand aloof Whilst I now write my friend Dr. Esdaile, to whom the public is already deeply indebted for services rendered humanity in India, and who I am proud to say was at one time my student, informs * See this gentleman's letter, published by me in the work already quoted; the original is now before me.