328 



Comparative Animal Physiology 



absence. However, the blood must always be at a higher COo tension than 

 the water and the hemocyanin (Hey) could unload only if the tissue oxygen 

 tensions are unusually low. 



Z 



o 

 o 



u 



X 



>- 



X 



o 



10 15 20 25 30 



OXYGEN PRESSURE 



Fig. 82. Oxygen dissociation curves of Limidus hemocyanin at different hydrogen 

 ion concentrations. From Redfield and Ingalls.^'" 



< 



o 

 o 



u 



I 

 > 



X 



o 



15 



20 



25 



35 



40 



45 



OXYGEN PRESSURE 



Fig. 83. Oxygen dissociation curves of Limiilus hemocyanin at different temperatures. 

 From Redfield and Ingalls.^-' 



In Hiisycon the arterial oxygen is at 36 mm. Hg and the venous at 6 mm. 

 Hg, corresponding to an unloading to the tissues of 1.7 volumes per cent. 

 Less than 10 per cent of this oxygen is carried in solution. ^''•^ Apparently in 

 Busycun the tissue oxygen tensions are verv low, and the hemocvanin trans- 



