426 THE BLOOD. [CH. xxvi. 



body ; they are found hi special abundance in red marrow, in 

 which at one time they were supposed to originate. But they do 

 not seem to be exclusively formed here. Some look upon each 

 eosinophile corpuscle as a little unicellular gland, and the mass 

 of corpuscles as a migratory glandular tissue. 



Chemistry of the Blood-Corpuscles. 



The white blood corpuscles. Our chemical knowledge of 

 the white corpuscles is small. Their nucleus consists of nuclein, 

 their cell-protoplasm yields proteids belonging to the globulin and 

 nucleo-proteid groups. The nucleo-proteid obtained from them is 

 not quite the same thing as fibrin-ferment (thrombin); it is probably 

 the zymogeii or precursor of the ferment (prothrombin) ; the action 

 of the calcium salts of the plasma in shed blood is to convert pro- 

 thrombin into thrombin (see p. 411). The protoplasm of these 

 cells often contains small quantities of fat and glycogen. 



The red blood corpuscles. 1000 parts of red corpuscles 

 contain : 



Water 688 parts. 



Solids / Organic 303-88 



ls \Inorganic . _. 8'i2 



One hundred parts of the dry organic matter contain 



Proteicl 5 to 12 parts. 



Haemoglobin 86 to 94 



Lecithin ....... 1'8 ,, 



Cholesterin O'l 



The proteid present is identical with the nucleo-proteid of white 

 corpuscles. The mineral matter consists chiefly of chlorides of 

 potassium and sodium, and phosphates of calcium and magnesium. 

 In man potassium chloride is more abundant than sodium 

 chloride ; this, however, does not hold good for all animals. 



Oxygen is contained in combination with the haemoglobin to 

 form oxy haemoglobin. The corpuscles also contain a certain 

 amount of carbonic acid. 



Haemoglobin and Oxyhaemoglobin. The pigment is by far 

 the most abundant and important of the constituents of the red 

 corpuscles. It is a substance which gives the reactions of a 

 proteid, but differs from other proteids in containing thp element 

 iron, and in being readily crystallisable. 



It exists in the blood in two conditions : in arterial blood it is 

 combined loosely with oxygen, is of a bright red colour, and is 

 called oxyha3moglobin ; the other condition is the deoxygenated 

 or reduced haemoglobin (better called simply haemoglobin). This 



