86 



ESSENTIALS OF CHEMICAL PHYSIOLOGY 



removed from the animal and hung in a cool place, the blood will not 

 coagulate for many hours. The corpuscles settle, and the supernatant 

 plasma can be removed with a pipette. 



The plasma is alkaline, yellowish in tint, and its specific gravity 

 is about 1026 to 1029. 



Its chief constituents may be enumerated as follows : — 



1,000 parts of plasma contain — 



Water .... 

 SoHds .... 

 Proteids : 1, yield of fibrin 

 2, other proteids 

 Extractives (including fpf) 

 Inorganic salts . 



902-90 



97-10 



4-05 



78-84 

 5-66 

 8-55 



In round numbers plasma contains 10 per cent, of solids, of which 

 8 per cent, are proteid in nature. The small quantity of fibrinogen 

 as indicated by the amount of fibrin formed should be carefully noted. 

 Serum contains the same three classes of constituents — proteids, 

 extractives, and salts. The extractives and salts are the same in the 

 two liquids. The proteids differ, as is shown in the following 

 table : — 



Proteids of Plasma 



Fibrinogen 

 Serum globulin 

 Serum albumin 



Proteids of Serum 



Serum globulin 



Serum albumin 



Fibrin ferment (nucleo-proteid) 



Fibrino-globulin 



The gases of the plasma and serum are small quantities of 

 oxygen, nitrogen, and carbonic acid. The greater part of the oxygen 

 of the blood is combined in the red corpuscles with haemoglobin ; 

 the carbonic acid is chiefly combined as carbonates (see Respieation). 



We may now consider one by one the various constituents of the 

 plasma and serum. 



A. Proteids — Fibrinogen. — This is the substance acted on by 

 fibrin ferment. It yields, under this action, an insoluble product 

 called fibrin, and a soluble proteid of the globulin class. 



Fibrinogen is a globulin. It differs from serum globulin, and may 

 be separated from it by the fact that half-saturation with sodium 

 chloride precipitates it. It coagulates by heat at the low temperature 

 of 56° C. As judged from the yield of fibrin, it is the least abundant 

 of the proteids of the plasma (see table on upper part of this page). 



Serum globulin and serum albumin. — These substances are con- 

 sidered in the practical exercises at the head of this lesson : see also 



