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COAGULATION OF THE BLOOD. 323
it has a proteolytic action only upon fibrin and not upon fibrinogen.
According to ’Nolf, coagulation is merely a preparation for the prote-
olysis, ;ui<l is a nutrition phenomenon, and in addition is of special
importance, In arresting hemorrhage. In order to prevent a rapid
fibrinolysis, the plasma also contains one or more antifibrinolytic sub-
stances, which are secreted by the liver.
What has been given contains the chief points in Nolf’s theory
of coagulation, and it is impossible in a text-book to enter more into
detail in regard to his remarkable investigations or the foundations
on which he bases his theory and the objections which can be raised
against it.
Recently other investigators as Rettger and Howell have raised
objections to the view that the coagulation of the blood is an enzymotic
process. Stromberg 1
also leans toward such a conception and they
all raise the objection that the quantity of fibrin increases with the quan-
tity of thrombin. This behavior, which has been known for a long time,
is of such a complicated nature, that no positive conclusions can be drawn
therefrom.
The belief of Mellanbt 2
that the plasma originally only contains one
globulin, fibrinogen, from which by enzymotic cleavage the fibrin and serglobulin
are formed, is untenable and is based upon the imperfect methods of preparing
fibrinogen that he used.
From the above description of the various theories of coagulation
it at least follows that in the study of the coagulation of the blood there
are many contradictor}’ statements and observations, and so many obscure
points, that for the present it is impossible to give a clear, comprehensive
summary of the different views and to deduce a theory of the process
of coagulation which would embrace all the factors. In spite of this
confusion and all contradictions, still we are sure that certain bodies such
as fibrinogen and thrombin, even though this latter be an enzyme or a
colloid combination, are directly concerned in the formation of fibrin,
while other bodies act indirectly as accelerators or inhibitors of coagulation.
The bodies accelerating coagulation, with the exception of gelatin,
whose action in this regard has not been positively proved, have been
mentioned several times above. The mode of action of the bodies retard-
ing coagulation is not clear and is much disputed. Their action may,
it seems, also be more of a direct or indirect kind. Thus, for example,
the oxalate and fluoride may prevent the formation of thrombin by
precipitation of the lime. The cobra-poison seems to prevent the forma-
1
Rettger, Amer. Journ. of Physiol., 24; Howell, ibid., 26; Stromberg, Bioch.
Zeitschr., 37.
2
Journ. of Phvsiol., 38.
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