BLOOD. 



477 



In the animal bocty haemoglobin is never saturated with ox3rgen, 

 even in arterial blood, while oxyhaemoglobin is never absent from venous 

 blood ; consequently, physiologically, we have to deal with an association 



of haemoglobin with oxyhsemoglobin, the relative proportions of each 

 varying in different localities and under different circumstances. 

 Further characteristics of these bodies will be studied in the chapter on 

 Respiration. 



