78 Appendices to Eighteenth Annual Report 



APPENDIX V. 



FURTHER INVESTIGATIONS ON THE LIFE-HISTORY 

 OF THE SALMON IN FRESH WATER. 



By D. NOEL PATON, M.D., F.R.C.P. Ed., 

 and M. I. NEWBIGIN, D.Sc. 



{From the Laboratory of the Royal College of Physicians of 

 Edinburgh.) 



A. Further Evidence ox the Factors determining the 

 Migration of Salmon from Sea to River. 



In the " Report on Investigations into the Life-History of the Salmon 

 in Fresh Water," published in 1898, the changes which the fish under- 

 goes between the months of May and November were dealt with, but 

 there was no material available to enable the observations to be 

 extended throughout the remaining five months of the year, from 

 December to April. 



The difficulty of getting an adequate supply of fish during these 

 close months is very great, but through the energetic co-operation of 

 Mr. Archer and his successor in the post of Inspector of Salmon 

 Fisheries, Mr. Calderwood, a certain number of fish have been procured 

 during these months from the estuaries of the Spey and the Dee. 



To the Duke of Richmond and Gordon, through his commissioner, 

 George Muirhead, Esq., and to the District Fishery Board of the 

 River Dee (Aberdeenshire), our thanks are due for generously sup- 

 plying us with material. 



In spite of the earnest endeavours of Mr. Archer and Mr. Calderwood, 

 it has been found impossible to get " clean" — unspawned — fish from the 

 upper waters during these months. 



The methods employed in the present investigation were those 

 described in our previous Report, pp. 3 to 7 ; and in comparing fish of 

 different sizes with one another, all weighings are expressed as for fish 

 of uniform size — 100 cm. in length - called the standard fish, S.F. 

 Weights are given in grammes. 



The following Tables give the results of the examinations and 

 analyses of twelve female fish taken in the estuaries during February, 

 March, and April. 



Although the amount of fats was determined in every case, it has 

 not been considered necessary to give the results of these analyses 

 apart from the analyses of the total solids. 



