DISSOCIATION OF OXY-HAEMOGLOIilN 



325 



below contains the results of a series of experiments on the blood 

 of a horse, where the amount of oxygen in the blood was determined 

 at various pressures. 



TABLE XLVTI 



From the figures in Table XL VII. it may be seen that much 

 the greater proportion of the oxygen is carried in combination with 

 the haemoglobin of the cells, and a relatively negligible proportion 

 in solution in the plasma. 



Oxygen load of corpuscle. 



The average normal man has about 5 litres of blood ; 2-5 litres 

 of this is occupied by 25 X 10^^ red corpuscles with a total surface 

 of about 3,000 sq. metres. When fully saturated with oxygen at 

 atmospheric pressure (160 mm. Hg) each litre of blood will take 

 up 200 c.c. of oxygen. Leaving out of account the relatively 

 small amounts of oxygen carried in solution in the plasma and 

 adsorbed by the plasma proteins, we may calculate that each 

 corpuscle will carry oxygen to the extent of 



Total oxygen capacity of blood 



Total number of corpuscles 



1000 

 25 X 10^2 



4 X 10-11 c.c. 



Each cubic centimetre of oxygen will need 25x10*^ corpuscles 

 to carry it. 



Further, the total iron content of human blood is about 2-5 

 grams (Schmidt). 



That is, each gram of iron is associated with 1000/2-5 = 400 c.c. 

 of oxygen — a figure closely approximating to Barcroft's experi- 



