Individual iao showed marked differences in resistance to oxygen deficiency. Lethal 

 values of oxygen ranged from 0. 50 to 1. 58 cc. /I. , the mean of the summer tests being 

 1. 10 cc. /I. and of the winter tests, 0.96 cc. /I. A similar range in lethal values was ob- 

 tained fronn the experiments where several fish were asphyxiated at once, but almost all 

 the values fell within the narrow interval from 0. 55 to 0. 85 cc. /I. , depressing the aver- 

 age to 0. 69 cc. /I. 



Over the temperature interval from 19 to 29 C. , the rate of oxygen consumption 

 increased slowly at first and then more rapidly at the higher temperatures. Lethal values 

 of oxygen, measured over the same range, also showed a greater increase between 26 

 and 31 C. 



26 



