2 ESDAILE, Results of the Salmon Scale Research. 



grounds to observe the colour changes, keeping the animals 

 at temperatures higher or lower than those to which they 

 are accustomed, testing them with different foods, and by- 

 many other methods of a similar kind. In the case of the 

 salmon in 191 1, Nature herself changed the conditions, 

 and carried out, as it were, a gigantic experiment which 

 man could never have performed himself Fortunately 

 he can record the results and so take full advantage of the 

 special conditions. 



The records of 191 1, besides being rendered more 

 interesting on account of the almost unique climatic 

 conditions, are unusual because they are the first of their 

 kind obtained from a series of fish caught during all months 

 in the year, permission having been granted for the use of 

 nets for scientific purposes during the close season of 191 1- 

 191 2. 



The scales were all taken from the " shoulder " of Wye 

 salmon caught either by nets or by rods. These scales were 

 examined and the fish classified according to the number of 

 years spent in the sea (See Table i). In a previous paper 

 (l) similar results were given for salmon caught in the 

 Wye during the years 1908, 1909, and 19 10. A compari- 

 son of the combined results of those years, with the results 

 of 191 1 (See Graphs i and 2 ), indicates that there were 

 considerable differences in the percentages of the various 

 classes of fish caught at different periods of the year. 

 The explanation of these variations is difficult to ascertain 

 as it is uncertain whether any can be given until much 

 more is known about the distribution and food of the 

 salmon while in the sea. Records of a large number of 

 fish have so far been taken systematically for only two 

 years, 1910 and 191 1, and we are therefore not in a posi- 

 tion to state what may be considered to be the normal 

 conditions. Many mistakes might be made if we stated 

 tliat this or that result was normal. This paper can only 



