

SECTION II 

 THE RED BLOOD CORPUSCLES 



THE red blood corpuscles, or erythrocytes, in man and other mammals are 

 nucleated bi-concave discs, about 7 to S/JL (-5 sW in.) in diameter and about 

 one-third of this in thickness. The colour of a single corpuscle when viewed 

 under the microscope is yellow, the red colour being apparent only when 

 larger numbers are seen together. The red corpuscles form about 50 per 

 cent, of the total mass of the blood, there being about 5,000,000 red corpuscles 

 in every cubic millimetre of blood. They are soft, flexible, and elastic, so that 

 they can readily squeeze through apertures and canals narrower than 

 themselves without undergoing permanent distortion. Each red corpuscle 

 consists of a framework or stroma, composed chiefly of protein material, 

 containing in its meshes or in a state of loose chemical combination a red 

 colouring matter, haemoglobin, to which is due the colour of the corpuscles 

 and of the blood itself. 



It is only in mammalia that the red corpuscles are of the character 

 described. In the camel they are oval in shape, but otherwise resemble the 

 corpuscles of other mammals. In all other classes of vertebrata the red 

 corpuscles are oval, nucleated cells. The hemoglobin is diffused through the 

 protoplasm of the cell body and does not extend to the nucleus. During 

 the early part of foetal lif e the corpuscles of mammals are also nucleated, but 

 in the adult condition the erythrocytes, except under abnormal conditions, 

 lose all traces of the nucleus before entering the blood stream. The small 

 size and great number of the red corpuscles determine that a very large area 

 of surface of red corpuscles is exposed to the plasma. The volume of each 

 corpuscle has been estimated as -0000000722 mm. 3 , and its surface as 

 000128 mm. 2 , so that the total surface of red corpuscles in the blood of a 

 man weighing about 70 kilos, (assuming his total blood as T V of the body 

 weight) would be about 3000 sq. metres, or 1500 times the surface of the 

 body itself. This great extent of surface is of importance in facilitating 

 the exchange of material, especially oxygen, between the corpuscle itself 

 and the surrounding plasma. 



OSMOTIC RELATIONSHIPS OF THE RED CORPUSCLE. If the blood 

 plasma be concentrated by evaporation or by the addition of neutral 

 salts, its osmotic pressure rises and water diffuses from the corpuscles into 

 the plasma in order to equalise the osmotic pressure within and without the 

 corpuscle. The latter therefore becomes wrinkled or crenated. On the 



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