OCTOBER 259 



growth specially dealt with was that from the time the 

 salmon parr assumes silvery scales and disappears from 

 the rivers, entering the sea, to be seen no more till it 

 reappears as a grilse. Much difference of opinion has 

 prevailed as to the length of time necessary to change 

 the smolt a creature five or six inches in length, weigh- 

 ing about one ounce into a grilse, measuring perhaps 

 twenty-four inches in length, and weighing four or five 

 pounds. Hitherto the nearest approach to precise data 

 was that made in the Stormontfield experiments half a 

 century ago, when smolts were marked by certain mutila- 

 tion of the fins. The report on these experiments pointed 

 to the almost incredible conclusion that the transition 

 from a one-ounce smolt to a four-pound grilse was 

 effected in two or three months. But the method of 

 marking adopted at Stormontfield was a very rude one. 

 It consisted merely in cutting off the little adipose, or 

 so-called ' dead,' fin, which is the distinctive badge of all 

 the salmon tribe; and as this was the common plan 

 resorted to by everybody who, for one reason or another, 

 returned a salmon at any stage of growth to the water, it 

 is obvious that no sound conclusion could be founded 

 upon such slippery data. The system of marking insti- 

 tuted by the Scottish Fishery Board leaves no room for 

 misinterpretation. A number is attached by silver wire 

 to the dorsal fin of the fish, which number corresponds 

 with that in the register giving the dimensions and date 

 of liberation. Mr. Calderwood's report is based upon the 

 results of that operation up to date. 



In the spring of 1905 six thousand five hundred smolts 

 were marked in this manner under direction of the 

 Tay Fisheries Company, of which Mr. P. D. Malloch, a 



