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320 THE BLOOD.
thrombin), which is then transformed by the alkali or acid into neozym (=/3-
thrombin). Nevertheless it is a fact that the quantity of thrombin in the serum
diminishes after coagulation, and that the thrombin action is considerably increased
by the addition of alkali or acid as well as by zymoplastic substances. The above
view as to the occurrence of different thrombins has not sufficient basis, and
Pekelharing x
has also raised objections thereto.
The theories of Morawitz, Fuld and Spiro at least stand in accord
with several known facts but do not take sufficient account of the action
of the zymoplastic substances of Alex. Schmidt. Thrombokinase is
precipitated, by alcohol and is not thermostabile, while the zymoplastic
substances, of Schmidt are thermostabile and soluble in alcohol. The
thrombokinase cannot therefore be identical with these zymoplastic
substances, and hence this theory does not explain the action of these
latter. Further, the mode of action of tissue extracts is unexplained,
and is a much disputed subject. It can be said that these two views are
in the main opposed to each other. According to one (Alex. Schmidt,
Arthtjs, Morawitz and others) they do not act like fibrin ferment,
but have an indirect action. According to the other (Pekelharing,
Huiskamp, Delezenne and Loeb 2
) they are thrombin, or at least bodies
having an analogous action.
Cramer and Pringle 3
have made the important observation that a
carefully prepared oxalate plasma when filtered through a Berkefeld
filter does not coagulate on adding calcium chloride, while the unfiltered
but centrifuged plasma does coagulate. The reason for this lies in the
fact that centrifuged plasma contains blood-plates, which are absent
in the filtered plasma. By means of these blood-plates, which yield
thrombokinase, the coagulation is produced on the addition of calcium
chloride. The points in Nolf’s theory of coagulation that are difficult
to understand as well as the observations of Freund (page 313) and of
Bordet and Gengou (page 314) are explained by this observation.
L. Loeb,4
who has carried out complete investigations on the coagulation of
blood, especially of Crustaceae, has arrived at the following view: The coagula-
tion in the Crustacea? can, according to him, be of two kinds. It may in part
be an agglutination of the amcebocytes and in part a fibrin formation from a fibrino-
gen of the plasma. This latter coagulation is essentially the same as occurs in
vertebrates. The substance acting here as the excitant for the coagulation is
also active in the absence of lime salts, and behaves therefore like a thrombin.
The tissues contain constituents which accelerate coagulation, which Loeb calls
coagnlins, which are not identical with the coagulins of the clot or the blood serum,
1
Bioch. Zeitschr., 11.
2
Huiskamp. Zeitschr. f. physiol. Chem., 34, 39; Delezenne, Arch. de. physiol.,
1897; Loeb, Biochem. Centralbl., 6, pages 829 and 889.
• Quarterly Journ. of exp. Physiol., 6.
4
Medical News, New York, 1903, and Virchow’s Arch., 176; Hofmeister’s Beitrage,
5, 6, 8. 9, and Biochem. Centralbl., 6, pages 829 and 889.
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