THE BLOOD 53 



weight, hence adult man has about five liters of blood, of 

 which about 35$ vol. is blood corpuscles and 65$ vol. 

 plasma. 



1. THE BLOOD CORPUSCLES 



i. The red blood corpuscles of man are soft, elastic, 

 biconcave disks with circular outlines. They are 7 8ju in 

 diameter, i.6yu thick, have a volume of 72 a 3 and a surface 

 of I28/A In thin layers they are yellowish green, in thicker 

 layers red ; they are heavier than the plasma and therefore 

 sink to the bottom when blood is allowed to stand. 



Man and most mammals have round, non-nucleated red blood 

 corpuscles; birds, reptiles, amphibians and fishes have oval, 

 nucleated red blood corpuscles. 



One cb.mm. of human blood contains, in the male about five, 

 in the female about 4.5 million red blood corpuscles; their sur- 

 faces are 640 and 576 sq.mm. respectively. This immense surface 

 favors the taking up and the giving off of oxygen in external and 

 internal respiration. The number of blood corpuscles is found by 

 counting the number found in an accurately measured quantity of 

 blood diluted to a given extent. The counting is done with the 

 aid of a microscope and a specially constructed slide. 



The number of red blood corpuscles is greater the higher the 

 altitude. 



The red blood corpuscles contain 65$ water and 35$ 

 solids. Of the solids the most important is 



The red coloring matter of blood, haemoglobin, which 

 forms about 87-95$ of the solid constituents of the blood 

 corpuscle (11-15$ f total blood); it is deposited in the 

 framework, the stroma, of the blood corpuscles. 



The haemoglobin of the blood corpuscle becomes dissolved in 

 the fluid of the blood by the addition of water, ether, chloroform 

 or bile to the blood; also by decomposition, by freezing, and by 

 thawing of the blood and by the passing through of strong electric 

 shocks. Blood, in which the coloring is dissolved in the fluid, is 

 transparent (laky-blood). 



The cause of this dissolving of haemoglobin in the blood fluid 

 after the addition of water, is the disturbance of the osmotic equi- 

 librium between the corpuscles and the surrounding fluid. The 

 corpuscles swell by the imbibing of water and are thereby 



