THE SAUION. 871 



placed by strong floods,) before they are hatched. The pa- 

 rents, however, immediately after their spawning, being 

 extremely emaciated, return to the salt water. Towards 

 the end of March the young fry begin to appear, and, gradu- 

 ally increasing in size, become in the beginning of May five 

 or six inches in length, when they are called salmon-smolts. 

 They now swarm in myriads in the rivers ; but the first flood 

 sweeps them down into the sea, scarcely leaving any behind. 

 About the middle of June the largest of these begin to 

 return into the rivers ; they are now become the length of 

 twelve to sixteen inches. Towards the end of July they are 

 called grilse, and weigh from six to nine pounds each. 



Fish entering some rivers much sooner than in others, the 

 salmon in them coming into breeding condition, and begin- 

 ning to spawn at an earlier period. 



In rivers issuing from large lakes salmon spawn earlier, 

 which is supposed to be owing to the waters being warmer and 

 having been purified by deposition in the lakes ; and it has 

 been noticed that rivers, swollen by the melting of snow in 

 the spring months, are later in their season of producing fish, 

 and are only successfully fished when rivers which emanate 

 from Likes are beginning to fail. Sir William Jardine has, 

 however, ascertained that the northern rivers, with few ex- 

 ceptions, are the, earliest to yield fish. This fact is also well 

 known to the fishmongers of London, and other great towns. 

 If we proceed further north, we find that the season of 

 spawn i:ig depends upon the temperature and the latitude. 

 We are informed by Artedi, that salmon spawn in Sweden 

 in the middle of summer. 



The variation in the spawning season in all probability 

 depends on the warmth of the waters of the respective 

 rivers, owing to the greater mass of water and warmer tem- 

 perature of their sources, or from passing through large lakes 



