Chap. IX] 



VASCULAR SYSTEM 



147 



of disintegrated cells. The number is usually about yV the number 

 of red corpuscles. 



Function. — When the blood leaves the blood-vessels and comes 

 in contact with foreign matter, the blood-plates and some of the 

 white corpuscles disintegrate and give rise to a substance called 

 prothrombin. This is acted upon by substances in the blood 

 plasma and converted into thrombin, which is one of the essentials 

 for the formation of a clot. 



Plasma. — The plasma of the blood is of a clear, slightly yel- 

 lowish color. It consists for the most part of water charged with 

 nutritive matter derived from our food, and waste matter derived 

 from the tissues. In other words, it consists of water holding in 

 solution or suspension : — 



r Serum-albumin. 

 Proteins . . . . < Para-globulin or serum-globulin. 

 I Fibrinogen. 



Sugars. 



Fats. 



Lecithin 



Cholesterin 



Urea 



Uric acid 



Hippuric acid 



Creatin 



Extractives 



Represent waste products. 



Inorganic Salts 



Gases . . 



Enzymes 



Internal Secretions 



Immune Bodies 



Chlorides 

 Sulphates 

 Phosphates 

 Carbonates 



( Ox.vgen. 



< Nitrogen. 



I Carbon Dioxide. 



of 



Sodium. 



Calcium. 



Magnesium. 



( Opsonins. 



I Antitoxins. 



I Antibacterial substances. 



Proteins. — There are many indications which support the 

 belief that the actual number of individual proteins is much greater 

 than the usual three mentioned in our list. Our knowledge of 

 these substances, and of the particular value of each one in the 

 system is limited. 



