54 HUMAN PHYSIOLOGY 



destroyed. Haemoglobin also leaves the blood corpuscles when 

 they are placed in the serum of another kind of animal. As such 

 serum has all the physical properties which make the existence of 

 the blood corpuscle possible, the cause of the passing out of the 

 haemoglobin must lie in the chemical difference of the various kinds 

 of serum. These differences are due to the proteids. The proteid 

 of one kind of serurn acts upon the corpuscle of another animal as 

 a poison (globulicidal action of the serum). 



The quantity of haemoglobin is estimated by colorimetry. A 

 measured quantity of blood is diluted with water till it has the 

 same color as a haemoglobin solution of known strength; from the 

 extent of the diluting, the quantity of haemoglobin can be found. 



For the chemical properties of haemoglobin, see page 32. 



Haemoglobin is of physiological importance because of its 

 power to unite with oxygen, forming a weak compound 

 called oxyhaemoglobin ; it therefore serves as the oxygen 

 carrier (see pages 33 and 58). 



The stroma of the red blood corpuscles, which remains 

 behind after the withdrawal of the coloring matter, is com- 

 posed of proteids, fat, lecithin, and cholesterin. Besides these 

 substances, the red blood corpuscles contain salts, especially 

 potassium chloride and potassium phosphate. 



The red blood corpuscles are continually destroyed in the 

 body in large numbers. The places of destruction are the 

 liver and the spleen. A restitution of this loss by the forma- 

 tion of new corpuscles takes place in the red bone marrow 

 (in the embryo also in the liver and spleen), the corpuscles 

 being formed from colored nucleated blood cells, the 

 haematoblasts. They are formed from these haematoblasts 

 by indirect division. At first, they still contain a nucleus, 

 but later on the nucleus disappears. 



2. The white blood corpuscles, also called leucocytes or 

 lymph corpuscles, are generally a little larger than the red 

 corpuscles; they are colorless cells with one or more nuclei. 

 They have no constant shape as they can change their form, 

 like the amoeba, and can also move about by the pushing 

 out and withdrawing of protoplasmic processes. At rest 

 they are spherical. 



