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 



