SALMON 27 



organs between any of these little creatures, how- 

 ever differing in colour. 



The Salmon has a peculiar formation of the eye, 

 the crystalline lens having the fibres of which it is 

 composed arranged as in the annexed sketch A, the 

 line m n being horizontal on one side, and vertical 

 on the other ; whereas in many of the Trout species 

 the fibres are arranged as at C, crossing one another, 

 or rather meeting at two opposite poles, like the 

 meridians of a globe, the line joining the two poles 

 being the axis of vision of the eye. 



" After examining the lenses of the Parr you sent 

 me/' says Sir David Brewster in a letter now before 

 me, " I found the structure to be exactly the same 

 as that of the Salmon. I have frequently had occa- 

 sion to mention the proofs that you gave me of the 

 identity of the Parr with the Salmon, and to men- 

 tion my own experiments on the lenses as con- 

 firmatory of your opinion that the Parr and the 

 Salmon are one and the same species/' 



Salmon begin spawning as early as September, 

 and continue to do so throughout the winter months ; 

 December, January, and February being the prin- 

 cipal ones for that operation. They continue on the 

 spawning ground, or Rade, as it is termed in Scot- 

 land, also during the spring months, though in 



