_ 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-dises 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 
_ a8 it is withdrawn from these, and is allowed to remain at 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 wiin 
’ fatty matter, and other organic substances ; with the addition 
of saline matter, of which a considerable proportion is chloride 
of sodium, or common salt. % proportion which the solid 
= 
q 
: LIQUOR SANGUINIS—COAGULATION. 211 
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