290 THE BLOOD. 



globin from hsemochromogen 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 blooa extrav- 

 asations, and whose origin from the blood-coloring matters seems to 

 be established (LANGHANS, CORDUA, QUINCKE, and others l ) . A solu- 

 tion of hsematoidin shows no absorption-bands, but only a strong absorp- 

 tion from the violet to the green (EWALD 2 ). 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, 3 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, methsemoglobin 

 or ha3matin, then the preparation of hsemin crystals is an absolutely 

 positive test. In regard to the detection of blood in urine see Chapter 

 XV 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. JOLLES 4 has suggested 

 a clinical method based on this procedure. 



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 oxyha?mo- 

 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 

 sides containing a layer of liquid 1 cm. thick (HOPPE-SEYLER'S ha?matinom- 

 eter). The use of HOPPE-SEYLER'S colorimetric double pipette is more 

 advantageous. Other good forms of apparatus have been constructed 

 by GIACOSA and ZANGERMEISTER. S Instead of an oxyhsemoglobin 



1 A comprehensive review of the literature pertaining to hsematoidin may be found 

 in Stadelmann, Der Icterus, etc., Stuttgart, 1891, pp. 3 and 45. 



2 Zeitschr. f . Biologic, 22, 475. 



3 Cit. from Gorup-Besanez, Lebrbuch d. physiol. Chem., 4. Aufl., 1878. 



4 Jolles, Pfluger's Arch., 65; Monatshefte f. Chem., 17. See also Oerum, Zeitschr. f 

 anal. Chem., 43; and the works cited in Maly's Jahresber., 33. 



5 F. Hoppe-Seyler, Zeitschr. f. physiol. Chem., 16; G. Hoppe-Seyler, ibid., 21; 

 Winternitz, ibid.; Giacosa, Maly's Jahresber., 26; Zangermeister, Zeitschr. f. Biolo- 

 gic, 33. 



