lO EsDAlLK, Results of the Salmon Scale Research. 



in the sea are heavier for their length than those which 

 spent only a short time in the salt water. From this it 

 might be expected that the curves of the averages of the 

 ratios of length and girth would correspond with those of 

 the averages of the ratios of length and weight. However, 

 the Graphs 5 and 9 indicate that this is not the case ; the 

 curves expressing the averages of the ratios of lengths 

 and girths do not show this decided decrease in the case 

 of those fish which have remained in the sea for three cr 

 more years. We find, therefore, that whereas the fish 

 become heavier in relation to their lengths the longer they 

 remained in the sea, this increase in weight is not accom- 

 panied b}' a corresponding increase in girth. 



Tassing on to a consideration of the amount of vari- 

 ation from the averages of the ratios of the different kinds 

 of fish there are some interesting results. In order to 

 make a correct comparison the coefficients of variation 

 have been used for this purpose. 



Pearson's formula for the calculation of the coefficients 

 of variation is as follows : — 



V t" wl 



Coefficient of variation = V // where M = mean, 

 AI 

 Z.t'-' = the sum of the squares of the deviations from the 

 average, « = the number of specimens examined. 



Graphs 4, 6. 8, and ! o indicate a considerable amount of 

 variation. In the results for 191 1 there seems to be some 

 definite connection between the averages of the ratios of 

 length and weight and length and girth and their co- 

 efficients of variation. This is to be noticed in the similarity 

 of the curves in the graphs ; the coefficients of variation are 

 higher where, in the corresponding kind, there is a high 

 average for the ratios, and, on the other hand, where there is 

 a low average there is a low coefficient. This shows clearly 

 that witli an increase in length for weight and length for 



