26 THE AGE AND GROWTH OF SALMON AND TROUT. 



classification of age according to size.* It thus represents the growth-curve 

 as indicated by one year only, the reliability of which we have already 

 investigated, and which I will call the " empiric curve." 



The unbroken line has been drawn through the points indicating the 

 values obtained by calculating the length of all the fish examined at the 

 completion of the first, second, and third, &c., winter-bands and without 

 reference to the year of birth.f This I call the "calculated curve." 



cm 

 2$ 



10 



10 



ft 



feergr?et kunx. 

 fmptrxsK Kurvt 



V7ntre 



FIG. 27. Comparison between an " Empiric " and a " Calculated" Curve of the 

 growth of 108 trout caught in the Eiver Chaigijok above Easti Lombola, 

 Lakselv, Finmarken, July 15 to 20, 1909. 



At each observation point on the curve I have put down the number of 

 examples on which the average values are based. 



We will now examine a comparison based on the above. 



It is easy to see that there is remarkably close agreement between these 

 two curves, so close in fact that it is difficult to imagine any closer coinci- 

 dence, and especially so when we consider the numerous small mistakes 

 which may occur in connection with the calculations on which these curves 

 are based. 



It should also be remembered that neither of these curves should really 

 run in straight lines from the observation points, which in the " empiric 

 curve " are during the summer and in the " calculated curve " in the mid- 

 winter life of the fish. In actuality both these curves should run in waves 

 with their minimum points in winter and the maximum points in summer. 

 This must, of course, follow from the fact that feeding and growth are much 



* Cf . Table XXXV. 



t Cf. Table XXXVc. 



