CHAPTER III. 



ON TROUT. 



ANYONE who knows the manifold variety of forms which trout may 

 assume in Norway, and the immense number of streams and lakes with 

 totally distinct conditions of existence in which they are found, will be aware 

 of the impossibility of attempting a geographical classification of the age 

 and growth of trout on similar lines to those we have followed in the case 

 of salmon. 



As a preliminary step, therefore, and merely as an introduction to the 

 study of trout-forms, I decided to collect a number of examples for an 

 initiatory comparison of characteristic forms to further a comparison 

 of the stock in various characteristic localities. 



In the first place I have endeavoured to obtain material which would 

 enable one to make a comparison between sea-trout and fresh-water trout in 

 their many " forms," such as burn-trout and trout from lakes where the fish 

 "are not big," trout from " good " lakes where the fish are large, and finally 

 the largest of all our trout forms the Mj0sen or " Hunner " trout. In 

 the second place I have made an attempt to investigate the stock in waters 

 to which both sea-trout and inland trout have access, and also at places 

 where the fresh-water form only is found, and where access from the 

 sea is impossible. 



As I shall point out later, all the differences which lend themselves to 

 demonstration may be reduced to variations in age and growth, and these 

 differences vary very considerably in separate localities, while there may 

 be intermediate stages of every sort and kind. 



The old division into burn-trout, mountain trout, lake trout, etc., 

 appears, therefore, of little use as a basis for discussion, nor would a classi- 

 fication according to growth and manner of growth be feasible without 

 elaborate proof ; I shall therefore confine myself to showing by means of 

 some characteristic instances the results of my investigations, and afterwards, 

 in a later chapter, deal with the growth and manner of growth of our sal- 

 monidae, and consider which types it might be possible to classify separately. 



I have put down in tabular form in the Appendix only as much of 

 my material as was necessary for evidence, and which was too voluminous 

 to be included in the text. 



