ABSTRACT 



As part of a study applying serological methods to 

 the distinction of salmon races , the normal serums of 

 human beings, cattle, horses, sheep, pigs, goats, brown 

 bullheads, and other salmon were tested for agglutinative 

 activity with the erythrocytes of sockeye salmon. Only 

 horse serum and pig serum reacted strongly with the salmon 

 cells. With some of the pig serums tested, consistent 

 differences were found in the strength of reaction of the 

 cells of individual sockeye salmon. The frequencies of 

 individuals displaying the various strengths of reaction 

 were found to differ significantly between areas of origin 

 of the salmon tested. When techniques of population ge- 

 netics were used, evidence for the possible genetic con- 

 trol of the observed differences was obtained. 



