60 MARVELS OF FISH LIFE 



The silvery appearance of the parr is due to the 

 fact that the scales become covered with the light reflect- 

 ing spicules already mentioned in an earlier chapter. 



If the scales are removed from a smolt the parr 

 markings, due to the arrangement of pigment cells in 

 the skin of the little fish, are seen as clearly as ever. 



In April and May the smolts drop down into the 

 sea and disappear. 



It has been comparatively easy to watch the parr 

 and the smolt while in fresh water, but when the smolt 

 goes to sea it is a totally different matter. 



During the last fifty years the life of the salmon 

 has engaged the attention of scientists and fishermen, 

 and the earlier knowledge gained about his life in the 

 sea has been obtained by the recapture of specimens 

 that had been marked. 



At first the method of marking fish mainly consisted 

 in cutting the fins, and this rough and ready method 

 is probably responsible for many of the conflicting state- 

 ments in the description of the life history of the salmon. 

 Latterly, fish have been marked by means of plates or 

 silver wire attached to the dorsal fin, each plate or wire 

 bearing a distinguishing number, and by this means 

 reliable information has been gained. 



In addition to marking, the fact that the age of 

 many bony fishes can be read by the formation of their 

 scales has been made use of. 



The scales consist of bony plates, which are partially 

 buried in pockets in the skin, and they overlap one 



