1 8 COAGULATION. 



tute, according to recent researches, more than a third of 

 the total weight of proteid. 



Serum albumin is soluble in water, and is not precipitated either by dilute 

 acids, by alkaline carbonates, or by NaCl. As it exists in the blood, it is pre- 

 cipitated by boiling or by addition of alcohol. It is Isevorotatory, and differs 

 from albumin of egg, in not being coagulated by ether, and in being more 

 soluble in HC1. Serum albumin can be separated from the soluble salts, 

 which are present in the serum, by prolonged diffusion with water. In this 

 state, however, its properties are altered ; it is neither coagulated by heat, nor 

 precipitated by alcohol. 



Globiilins. The globulins are distinguished from common serum albumin 

 by the fact that while insoluble in concentrated solutions of neutral salts, 

 particularly NaCl and MgSO 4 and in distilled water, they are soluble in 

 weak solutions : they are also soluble in dilute alkalies. They are all 

 coagulable by heat, but at different temperatures. 



Paraglobulin is the precipitate produced in serum by saturating it with 

 NaCl or MgSO 4 , or by diluting it and then neutralizing with acetic acid, or 

 by passing through it a current of CO 2 . This precipitate is soluble in one 

 per cent, solution of NaCl and coagulates at 73 C. It is contained, along 

 with serum albumin, in all the tissues and liquids of the body. 



Fibrinogen is distinguished from paraglobulin by the greater difficulty with 

 which it is precipitated by dilution in neutral solution. It is contained in all 

 the coagulable liquids. Its solution in NaCl is coagulated by heat at 55 C. 

 (Hammarsten). 



Fibrin differs from fibrinogen in its filamentous structure, and its solubility 

 in dilute NaCl solution. Like myosin, it is soluble in strong solutions of 

 NaCl, but with great difficulty : the solution coagulates at about 60 C. 

 It is convertible with difficulty by acids or by alkalies into albuminate. 

 Crude fibrin decomposes solution of H 2 O 2 : it is converted by boiling into a 

 body resembling coagulated albumin. 



The liquids contained in uninflamed serous cavities, 

 which coagulate imperfectly (pericardial fluid) or not at 

 all (hydrocele fluid), also contain both forms of globulin. 

 These liquids for the most part coagulate on the addition 

 of serum. Their percentage of fibrin-yielding material is, 

 however, small. 



From blood which has been a short time withdrawn 

 from the circulation a ferment-like substance can be 

 prepared, the solution of which, although it contains no 

 globulin, promotes the coagulation of coagulable fluids. 



In coagulation many of the colourless corpuscles of the 



