6 American Fisheries Society 



the development of one set of organs at the expense of 

 material derived from other organs, form a unique bio- 

 logical experiment in nutrition. The experiment is un- 

 usually favorable also because of the fact that it is 

 carried out in nature under conditions that must be as- 

 sumed to be normal and natural for the animal itself. 

 The source of the material from which is derived, first, 

 the energy represented by the journey against the swift 

 currents of the rivers, and second, the material used in 

 the construction of the reproductive organs, forms the 

 basis for the work of which the present brief report is 

 only a small part. 



This problem was attacked many years ago by 

 Miescher, whose classic work on the Rhine salmon is 

 well known. Later it was again resumed by Noel-Paton, 

 working under the auspices of the Scottish Fishery 

 Board and on the same species, Salmo salar. The Atlan- 

 tic salmon, however, while it makes the run in fresh 

 water without food, nevertheless is supposed to live to 

 return to salt water where it again begins to feed. It 

 remains to be seen whether or not the changes are as 

 profound and as exhaustive as are found in the king 

 salmon of the Pacific. 



In 1906, after a series of preliminary studies extend- 

 ing through three summers, I made an exhaustive col- 

 lection of samples of king salmon from the Sacramento 

 River basin, California. This collection began with the 

 sea-run fish caught while feeding at Monterey Bay and 

 at Bolinas Bay, California. It included a series of 

 samples taken from brackish water at Black Diamond 

 on the Sacramento River, and closed with a similar col- 

 lection from the spawning grounds of the McCloud River 

 at the U. S. Fishery at Baird, California. 



It is obvious that where marked changes are in prog- 

 ress in a series of animals upon which comparisons are 

 drawn, some standard must be chosen as the basis of 

 this comparison. In the case of the salmon the sup- 

 posedly mature fish at the feeding grounds just before 

 entering the fresh water is taken as a standard against 



