PACIFIC SALMON 



79 



1800 

 1713 



1600 

 1400 

 1200 

 1000 

 800 



€00 



500 



I I' 



Temperature Centigrade 





1117\C 





B 



505 



33 



36 



39 



42 



3 6 9 12 15 18 21 24 27 30 



Fig. 2. Curve AB represents the relation between the carbon dioxide solubility coefficient .in 

 distilled water and temperature. the point c is the solubility of carbon dioxide at 12° c. 



with glacier water. The seep and spring 

 water could not be of deep origin since the 

 ground never thaws to any great depth. It 

 would be logical to suppose that the carbon 

 dioxide tension of the water of Copper 

 River would approximate the carbon diox- 

 ide partial pressure of the atmosphere. If 

 this be true, the colder the water the lower 

 its carbon dioxide tension (the heating of 

 water without loss of carbon dioxide in- 

 creases its carbon dioxide tension). Thus, 

 the salmon could be reacting to carbon di- 

 oxide tension at the same time that it was 

 reacting to temperature. Regardless of 

 what the fish was responding to, these 

 observations (Ward, 1921) are proof that 



the red salmon can and does react to factors 

 of its environment. 



A more crucial test is the results of arti- 

 ficial planting of the Pacific coast salmon. 

 Davidson and Hutchinson (1938) have 

 treated this subject in an excellent manner. 

 Of some 15 and more repeated attempts 

 to plant the Pacific coast salmon Onco- 

 rhynchus, only five have been successful in 

 developing natural populations with charac- 

 teristics similar to those in their native dis- 

 tribution. These authors have summarized 

 the situation of the development of natural 

 populations. 



"The environmental components, as con- 

 sidered in this study of the foreign streams 



