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322 THE BLOOD.
is formed. Thrombin is a fibrin incompletely saturated with fibrinogen,
and in the coagulation of fibrinogen with thrombin the still unsatisfied
affinities of the latter are saturated. ("La thrombine d’A. Schmidt n’est-
pas autre chose que de la fibrine insuffisamment pourvue de fibrinogene.
Dans la coagulation du fibrinogene par la thrombine les affinites restees
libres de celle-ci peuvent s’assouvir; le compose moins sature se trans-
forme en un compose plus satureV’) The formation of fibrin from
fibrinogen is not, according to Nolf, an enzymotic process, and the
thrombin is only a residue of the fibrin remaining in solution.
In Nolf’s opinion the thrombogen is probably formed in the liver
and found to a large extent in all plasma. The thrombozym is secreted
by the leucocytes and the endothelial cells, and in opposition to Mora-
witz is not secreted by other cells. It is also a normal constituent of the
blood-plasma circulating in the living body. Most tissues, on the con-
trary, contain no thrombozym. The tissue extracts, Nolf believes,
also contain no substances absolutely necessary for the coagulation,
but only bodies which can have a powerful accelerating action, the
thromboplastic substances which are mixed with the thrombokinase of
Morawitz. The circulating blood-plasma contains all the bodies directly
necessary in the coagulation, namely, fibrinogen, thrombogen, throm-
bozym and lime salts. Besides these it also contains a substance that
inhibits coagulation, antithrombin, which is formed in the liver. There
exists, if the author understands the work of Nolf, a labile equilibrium
between the various constituents of the plasma, and this equilibrium is
destroyed in coagulation. The first impulse to coagulation is given by
the thromboplastic substances.
Nolf considers as thromboplastic active any influence of a physical
or chemical nature which, be it produced by the walls of the vessel, a
suspended body, a solvent or a dissolved body, a colloid or crystalloid,
a molecule or an ion, makes the combination of the three above colloids
possible. To the thromboplastic agents belong the walls of a glass
vessel, finely powdered glass, the precipitates of calcium oxalate or
calcium fluoride, also living protoplasm, aqueous tissue extracts, the
alcohol soluble zymoplastic substances of Alex. Schmidt, and other
substances. All these agents in some way or other may serve as points
of precipitation. That a plasma free from form-elements coagulates
for example on contact with the walls of a glass vessel depends upon the
fact that the inhibitory action of the antithrombin is retarded by the
thromboplastic action of the foreign surface. Unfortunately we are
ox 1 certain as to how this thromboplastic action is brought about.
An important side of Nolf’s theory of coagulation is also the fibrinol-
ysis whifli is brought about by the thrombin. The proteolytic action
of the thrombin is due only to the thrombozym contained therein, and
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