SALMON. 25 



The Salmon has a peculiar formation of the eye, 

 the crystalline lens having the fibres of Avhicli 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 jjoles, lil^e 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 Salmo7i. I have frequently had occasion to mention 

 the proofs that you gave me of the identity of the Parr 

 with the Salmon, and to mention my own experiments 

 on the lenses as confirmatory 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 ; De- 

 cember, January, and February being the principal ones 

 for that operation. They continue on the spawning- 

 ground, or Hade, as it is termed in Scotland, also during 

 the spring months, though in diminished quantities. I 

 myself have caught full roeners, as they are called, in the 

 month of May in the Tweed. Now we know from the 



