Bauhaus-Universität Weimar

The Cyclopaedia of Anatomy and Physiology, vol. 4: Pla [corr.: Ple] - Wri
Todd, Robert Bentley
VEIN. 1393 
certain conditions which must occur before 
coagulation can develop itself. While the 
blood, itself in a state of health, remains in. 
contact with the lining membrane of healthy 
blood vessels, coagulation is impossible ; but 
under certain conditions of disease the blood 
loses its fluidity, and these conditions may 
either consist in some abnormality of the ves¬ 
sel’s walls, or in some foreign matters becom¬ 
ing mixed with the blood, — the former in¬ 
fluence being passive, and the latter an active 
agent in producing or hastening coagulation. 
I would here urge the doctrine that the 
vascular cavity, —the hollows of all the tubu¬ 
lar vessels (veins, arteries, and lymphatics), 
together with the ventricles and auricles of 
the heart, — constitutes a true serous shut 
sac, much complicated in form and modified 
by its peculiar functions, it is true ; but pos¬ 
sessing the same anatomical elements, — an 
epithelial pavement placed upon a sheet of 
limitary tissue, on the other side of which is 
situated a nutrient vascular system. I would 
here urge this view, because it applies with 
much force to certain questions in venous 
pathology, and to few more so than the one 
under consideration, where arguments by 
analogy are a desideratum. The lining mem¬ 
brane of the veins then is a serous membrane. 
On the surface of other serous membranes — 
pleura, pericardium, &c.—plastic effusion con¬ 
sists Of sheets of lymph, and a certain amount 
of serum. By analogy we, à priori, conclude 
that lymph is effused in inflammation on the 
lining surface of the veins, and this the experi¬ 
ments of Gendrin and Hope have established 
by indisputable proof. That the inflammatory 
product consists partly of serum as well as 
lymph is supported by analogy alone ; but 
if admitted would explain the coagulation 
of the blood to complete the clot, which is 
known to be so much facilitated by the ad¬ 
mixture of foreign or abnormal secretions. 
Whatever may be the opinion of the forma¬ 
tion of the coagulum, its characters are these : 
— it consists of concentric laminae, brownish, 
yellowish, or white, of which the central are 
the darkest and softest; and sometimes the 
centre is nearly fluid blood. The density of the 
entire clot is subject to much variety. The 
coagulum is moulded to the cavity of the vein, 
and sometimes present the exact impression of 
the valves. Mr. Arnott has made an interesting 
observation with respect to the coagulum, 
that it extends along the affected vein usu¬ 
ally to the next collateral branch, and there 
abruptly ceases. The true explanation of 
this circumstance is doubtless that given by 
Mr. Henry Lee.* “ When any portion of 
a vein is obstructed, the blood is kept at 
rest between the obstruction and the next 
collateral branch ; and, if disposed to coagu¬ 
late, there is nothing to interfere with such 
an action. But the case is different as soon 
as one vein opens into another. A fresh cur¬ 
rent of blood is then continually sweeping the 
* On Phlebitis and Purulent Deposits, by Henry 
Lee, Lond. 1850, p. 23. 
orifice of the obstructed vessel ; and even 
although the blood at this point should have 
a tendency to coagulate, it is carried on in the 
course of the circulation, before it can adhere 
to the sides of the unobstructed vein.” 
The coagulum thus extends towards the 
heart, beyond the limits of the inflamed por¬ 
tion, having a mere mechanical boundary. It 
extends also at the distal end, but here it 
becomes gradually attenuated : it often rami¬ 
fies into many branches and subdivisions of 
the veins that are tributary to the one ob¬ 
structed, especially where they are not re¬ 
lieved by collateral anastomoses. At those 
points where inflammation has not occurred, 
and the coagulation has been favoured by me¬ 
chanical circumstances simply, the clot scarcely 
adheres to the lining membrane of the vein. 
But the plastic product is not always in the 
form of a plug, moulded to the cavity of the 
vein : it sometimes consists of shreds or 
fringes of lymph, firmly attached to the lining 
of the vein, and hanging into its cavity, either 
from the walls or in festoons from the valves.* 
The walls of the vein, at the same time, 
undergo change, indicative of the same inflam¬ 
matory phenomena, which consists mainly in 
interstitial plastic deposit among the areolar 
tissue of the tunics. 
“ So soon as a fibrinous plug of this de¬ 
scription is established, the red and violet 
speckled colouring abates in intensity, and 
the internal membrane, losing its smoothness 
and polish, assumes a dull velvety or slightly 
puckered appearance. The external mem¬ 
brane appears thickened, turgid, and soon 
becomes adherent to the cellular tissue, which 
in its turn has been rendered firmer and paler 
from the effusion of plastic lymph. Both 
membranes are still readily distinguishable, 
and even separable, from each other ; the con¬ 
sistency of their texture is however impaired, 
and they are easily torn. In this state of 
things a vein, when cut asunder, does not col¬ 
lapse, even after the plug has been removed ; 
but, on the contrary, its calibre remains open 
like that of an artery. This is more than ever 
the case when the surrounding cellular tex¬ 
ture has acquired firmness by the condensa¬ 
tion of the inflammatory product infused into 
it, or when it puts on a brawn-like character, 
and intimately coalesces with the external 
membrane of the vessel.-f- 
These phænomena may occur in veins of 
any size ; and to any extent in an} particular 
set of vessels. They occasion obstruction of 
the circulation in all vessels tributary to the 
one affected. Of such a condition Phlegmasia 
alba dolens may be instanced as an example. 
As regards the cause of plastic phlebitis, 
or, indeed, of venous inflammation in general, 
it may be the result either of spontaneous 
action, or the circulation of poisoned blood— 
the latter being infinitely the most common 
* See Cooper and Travers’s Essays, Lond. 1818, 
part i. plate 10. 
f Hasse’s Pathological Anatomy, Sydenham So ■ 
ciety’s translation, Lond. 1846, p. 13. 
4 u


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