the spawned grilse of 4 lb. weight were marked by putting a peculiarly twisted piece of wire through the dorsal fin.  They were immediately thrown into the river, and of course disappeared, making their way downwards with other spawned fish towards the sea.  “In the course of the next summer we again caught several of those fish which we had thus marked with wire as 4 lb. grilse, grown in the short period of four or five months into beautiful full-formed salmon, ranging from 9 lb. to 14 lb. in weight, the difference still depending on the length of their sojourn in the sea.”

In January 1842, he repeated the same process of marking 4 lb. grilse which had spawned, and were therefore about to seek the sea; but, instead of placing the wire in the back fin, he this year fixed it in the upper lobe of the tail, or caudal fin.  On their return from the sea, he caught many of these quondam grilse converted into salmon as before.  The following lists will serve to illustrate the rate of growth:—­

List of Grilse marked after having spawned, and re-captured as Salmon, on their second ascent from the Sea.

Period of        Period of       Weight when    Weight when
marking.        recapture.        marked.        retaken.

1841.  Feb. 18. 1841.  June 23. 4 lbs. 9 lbs.
       ... 18. ... 23. 4 lbs. 11 lbs.
       ... 18. ... 25. 4 lbs. 9 lbs.
       ... 18. ... 25. 4 lbs. 10 lbs.
       ... 18.  July 27. 4 lbs. 13 lbs.
       ... 18. ... 28. 4 lbs. 10 lbs. 
      March 4.  July 1. 4 lbs. 12 lbs.
       ... 4. ... 1. 4 lbs. 14 lbs.
       ... 4. ... 27. 4 lbs. 12 lbs.

1842.  Jan. 29. 1842.  July 4. 4 lbs. 8 lbs.[20]
       ... 29. ... 14. 4 lbs. 9 lbs.[20]
       ... 29. ... 14. 4 lbs. 8 lbs. 
      March 8. ... 23. 4 lbs. 9 lbs. 
      Jan. 29. ... 29. 4 lbs. 11 lbs. 
      March 8.  Aug. 4. 4 lbs. 10 lbs. 
      Jan. 29. ... 11. 4 lbs. 12 lbs.

During both these seasons, Mr Young informs us, he caught far more marked grilse returning with the form and attributes of perfect salmon, than are recorded in the preceding lists.  “In many specimens the wires had been torn from the fins, either by the action of the nets or other casualties; and, although I could myself recognise distinctly that they were the fish I had marked, I kept no note of them.  All those recorded in my lists returned and were captured with the twisted wires complete, the same as the specimens transmitted for your examination.”

    [20] These two specimens, with their wire marks in situ, may
    now be seen in the Museum of the Royal Society of Edinburgh.