THE COMPOSITION OF THE WHITE CORPUSCLES 117 



terin, etc., a total of 0.5 to 0.6 per cent. The dextrose content amounts 

 to from o.i to 0.15 per cent. 



Ferments are also found in blood; first, a diastatic ferment converting 

 amyloids into sugars; second, a glycolytic ferment causing a disappearance 

 of sugar; third, a fat-splitting ferment, lipase; and fourth, fibrin ferment 

 (thrombin), or its 'precursor, prothrombin. 



Inorganic Substances. The blood plasma contains about 0.8 per cent 

 of inorganic salts distributed as follows, the sodium chloride predominating: 



Parts in 1,000 of plasma. 



Chlorine 3-536 



Sulphuric acid 1 29 



Phosphoric acid 145 



Potassium 314 



Sodium 3-410 



Phosphate of lime 298 



Phosphate of magnesia 218 



Oxygen 455 



The Serum. The serum is the liquid part of the blood or of the 

 plasma which remains after the fibrin has been formed and removed. It is 

 a transparent, yellowish, faintly alkaline fluid, with a specific gravity of 

 from 1025 to 1032. Serum may be obtained from blood-corpuscles by allow- 

 ing blood to clot in large test tubes, or by subjecting test tubes of whipped 

 blood to the action of a centrifugal machine for some time. Serum is chemi- 

 cally very much the same as plasma except that it has lost the fibrinogen in 

 the process of clotting and has gained the by-products of that process throm- 

 bin, thrombokinase, and fibrin-globulin. The salts of serum are practically 

 those of plasma. 



The Composition of the White Corpuscles. The white corpuscles 

 are comparatively undifferentiated cellular elements, hence possess the chemi- 

 cal composition of protoplasm. Lillienfeld has made an analysis of the 

 leucocytes of thymus gland from the calf, which contain 11.49 P er cent of 

 solids, as follows: 



In 100 Parts of Dry Substance of Corpuscles of Calf. 



Per cent. 



Proteid i . 76 



Leuconuclein 68. 78 



Histon 8.76 



Lecithin 7.51 



Fat 4-02 



Cholesterin 4.40 



Glycogen 0.80 



96.03 



