282 THE BLOOD. 



by the aid of special appliances (L. LEWIN, MIETHE, and STENGER) the 

 band first described by SORET and then by GAMGEE in the ultra-violet 

 portion. This violet band, X = 415, is of importance in the detection 

 of very small quantities of blood. While the two oxyhsemoglobin bands 

 are still detectable in a dilution of 1 :14,700 the violet band may be seen, 

 according to LEWIN, MIETHE and STENGER l in a dilution of 1 :40,000. 



The observation of PIETTRE and VILA that so-called laky blood and oxyhaemo- 

 globin solutions in thick layers also show a third band in the red (X = 634) depends 

 in all probability, as also claimed by VILLE and DERRIEN, upon a partial forma- 

 tion of methsemoglobin which according to ARON 2 exists preformed in all blood. 



A great many methods have been proposed for the preparation of 

 oxyhsemoglobin crystals, but in their chief features they all agree with 

 the following one suggested by HOPPE-SEYLER: The washed blood- 

 corpuscles (best those from the dog or the horse) are stirred with 2 

 vols. of water and then shaken with ether. After decanting the ether and 

 allowing the ether which is retained by the blood solution to evaporate 

 in an open dish in the air, cool the filtered blood solution to C., add 

 while stirring one-fourth vol. of alcohol also cooled, and allow to stand 

 a few days at 5 to 10 C. The crystals which separate may be 

 repeatedly recrystallized by dissolving in water of about 35 C., cooling, 

 and adding cooled alcohol as above. Lastly, they are washed with 

 cooled water containing alcohol (one-quarter vol. alcohol) and dried 

 hi vacuum at 6 C. or a lower temperature. 3 



For the preparation of oxyhsemoglobin crystals in small quantities 

 from easily crystallizable blood, it is often sufficient to stir a drop of 

 blood with a little water on a microscope slide and allow the mixture 

 to evaporate so that the drop is surrounded by a dried ring. After 

 covering with a cover-glass, the crystals gradually appear radiating from 

 the ring. These crystals are formed more surely if the blood is first 

 mixed with some water in a test-tube and shaken with ether, and a drop 

 of the lower deep-colored liquid treated as above on the slide. 



Haemoglobin, also called REDUCED HAEMOGLOBIN or PURPLE CRUORIN 

 (STOKES 4 ), occurs only in very small quantities in arterial blood, in 

 larger quantities in venous blood, and is almost the only blood-coloring 

 matter after asphyxiation. 



Hsemoglobin is much more soluble than the oxyhsemoglobin, and 

 it can therefore be obtained as crystals only with difficulty. These 



, cited in Maly's Jaresb., 8; Gamgee, Zeitschr. f. Biol., 34; Lewin, Miethe 

 and Stenger, Pfliiger's Arch., 118; Lewin and Miethe, ibid., 121. 



2 Piettre and Vila, Compt. Rend., 140; Ville and Derrien, ibid., 140; Aron, Biochem. 

 Zeitschr., 3. 



3 In regard to the preparation of oxyhsemoglobin, see also Hoppe-Seyler-Thier- 

 felder's Handbuch, 8. Aufl.; also the works cited in footnote 1, p. 278; also Schuur- 

 manns-Stekhoven, Zeitschr. f. physiol. Chem., 33, 296; see also Bohr, Skand. Arch. 

 f. Physiol., 3; J. Offringa, Bioch. Zeitschr., 28. 



4 Philosophical Magazine, 28, No. 190, Nov., 1864. 



