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KLEMATOIDIN. 301
Zaleski considers this pigment as a hydrogcnized haemin. A regenera-
tion of haematin from haematoporphyrin has been performed by Laid-
law. If ha’matoporphyrin is dissolved in dilute ammonia and warmed
with Stokes’ solution and hydrazine hydrate, iron is taken up again
and haemochromogen is produced, which is changed into hsematin by
shaking with air. According to Ham and Balean,1
it is possible to pro-
duce haemoglobin from haemochromogen and globin, and it is indeed
possible that other proteins can replace globin in this formation.
Haematoidin, thus called by Virchow, is a pigment which crystallizes
in orange-colored rhombic plates, and which occurs in old blood extrav-
asations, and whose origin from the blood-coloring matters seems to
be established (Langhans, Cordua, Quincke, and others 2
). A solu-
tion of haematoidin shows no absorption-bands, but only a strong absorp-
tion from the violet to the green (Ewald 3
). According to most observers,
haematoidin is identical with the bile-pigment bilirubin. It is not
identical with the crystallizable lutein from the corpora lutea of the ovaries
of the cow (Piccolo and Lieben,4
Kuhne and Ewald).
In the detection of the above-described blood-coloring matters the
spectroscope is the only entirely trustworthy means of investigation.
If it is only necessary to test for blood in general and not to determine
definitely whether the coloring-matter is haemoglobin, methaemoglobin
or haematin, then the preparation of haemin crystals is an absolutely
positive test. In regard to the detection of blood in urine, see Chapter
XIV, and for the detection of blood in intestinal contents, in pathological
fluids and in chemico-legal cases we must refer the reader to more extended
text-books.
The methods proposed for the quantitative estimation of the blood-
coloring matters are partly chemical and partly physical.
Among the chemical methods to be mentioned is the incineration of the
blood and the determination of the amount of iron contained in the ash from
which the amount of haemoglobin may be calculated. We must refer to works
on chemical methods of investigation in regard to these methods.
The physical methods consist either of colorimetric or of spectroscopic
investigations.
The principle of Hoppe-Seyler’s colorimetric method is that a measured
quantity of blood is diluted with an exactly measured quantity of water
until the diluted blood solution has the same color as a pure oxy haemo-
globin solution of a known strength. The amount of coloring-matter
present in the undiluted blood may be easily calculated from the degree
of dilution. In the colorimetric testing we use a glass vessel with parallel
1
Zaleski, Zeitsehr. f. physiol. Chem., 43; Laidlaw, Journ. of Physiol., 31; Ham
and Balean, ibid., 32.
2
A comprehensive review of the literature pertaining to haematoidin may be found
in Stadelmann, Der Icterus, etc., Stuttgart, 1891, pp. 3 and 45.
» Zeitsehr. f. Biologie, 22, 475.
4
Cit. from Gorup-Besanez, Lehrbuch d. physiol. Chem., 4. Aufl., 1878.
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