LIQUOR SANGUINIS COAGULATION. 211 



sively of the fibrous network, is very firm in its texture, 

 being sometimes almost leathery in its character ; whilst the 

 lower part of the clot, which is chiefly composed of the red 

 particles, loosely bound together by scattered fibres, is very 

 soft, and easily broken asunder. This effect may be also 

 produced, by acting on healthy blood with certain substances 

 which retard its coagulation, such as a strong solution of 

 Glauber's salt ; for if sufficient time is allowed, the red par- 

 ticles will subside in consequence of their greater specific 

 gravity, leaving a colourless layer of fibrin above them. It 

 is of the liquor sanguinis, in a concentrated form, that those 

 exudations consist, which are poured out from the blood for 

 the repair of injuries, and which pass spontaneously into the 

 condition of a simple form of tissue ( 393). 



237. When a very thin slice of the clot is examined with 

 a microscope, it is found to be made up of a net-work of an 

 imperfectly fibrous character, interlacing in every direction, 

 and including the blood-discs in its meshes. These fibres are 

 produced by the spontaneous change in the fibrin of the blood, 

 from the fluid to the solid form. So long as the blood is 

 circulating in the vessels of the living body, so long does its 

 fibrin remain dissolved in the watery part of it ; but so soon 

 as it is withdrawn from these, and is allowed to remain at 

 rest, it undergoes this remarkable change. If fresh-drawn 

 blood be continually stirred with a stick or beaten with twigs, 

 the fibrin coagulates in irregular strings, which adhere to the 

 stick or twigs ; and it does not then include the red particles, 

 which are left behind in the fluid. In this manner it may be 

 completely separated from the other elements of the blood, 

 which have not in themselves the least tendency to coagulate 

 spontaneously. Although forming a large proportion of the 

 substance of the clot, the fibrin, when dried, does not consti 

 tute more than from 2 to 3 parts by weight in 1000 of blood. 

 This proportion is augmented to 6, 8, or even 10 parts, in 

 severe inflammatory diseases. 



238. "When the fibrin and the red particles have both been 

 separated from the blood, there remains a fluid, the serum. 

 in which a good deal of albumen is dissolved, together wii-n 

 fatty matter, and other organic substances ; with the addition 

 of saline matter, of which a considerable proportion is chloride 

 of sodium, or common salt. The proportion which the solid 



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