78 PATHOLOGY. 



wlieu treated with chemical re-agents, even with such as do 

 not produce any appreciable effect on its chemical composition, 

 it very speedily loses its peculiar power of causing serous fluids 

 to coagulate. For instance, this power is destroyed by an excess 

 of alkali, or by the presence of acids. 



" Hence, though there is great reason to believe that the 

 Hhrino-plastic globidin (as it has been called) which exists in 

 serum does really come from the red corpuscles, the globulin, 

 which is obtained in large quantities from these bodies by the 

 use of powerful re-agents, has no coagulating effect at all on 

 pericardial or other serous fluids. 



" Though globuhn is so susceptible of change when in solution, 

 it may be dried at a low temperature, and kept in the form of 

 powder for many montlis without losing its coagulating power. 



" Thus globuhn, added, under proper conditions, to serous 

 effusion, is a coagulator of that effusion, giving rise to the 

 development of fibrin in it." 



The latest theories of coagulation slightly modify the above. 

 Thus Schmidt says that the fibrin is formed by the coming 

 together of two proteid substances which occur dissolved in the 

 plasma, viz. — (1) fibrinogen, i.e., the substance which yields the 

 chief mass of the fibrin ; and (2) fibrino-plastic substance, or 

 fibrino-plastin. The latter terms are now rarely used, having 

 been replaced by either of the following — serum-globulin or 

 paraglobulin. In order to determine the coagulation a ferment 

 seems necessary, and this is supplied by (3) the fibrin ferment. 



Both fibrinogen and fibrino-plastin belong to the group of 

 proteids called globulins. They are insoluble in pure water, but 

 are soluble in dilute saline solutions (common salt, 1 per 

 cent), phosphates of the alkaline earths, and calcium sulphate. 

 They are not distinguished from each other by any marked 

 chemical characters, but differ in the following particulars : 

 Fibrino-plastin or paraglobulin — serum-globulin — is only ap- 

 preciably precipitated when a solution of sodium salt of at least 

 20 per cent, has been added, whereas fibrinogen is easily pre- 

 cipitated by the solution of salt (sodium chloride), when it only 

 reaches 16 per cent. 



Again, the very light granular precipitate of paraglobulin is 

 more easily dissolved than that of fibrinogen, and its solution 

 only begins to coagulate at 133° Y., whereas that of fibrinogen 



