HAEMOGLOBIN. 275 



containing alcohol (one-quarter vol. alcohol) and dried in vacuum at 



C. or a lower temperature. 1 



For the preparation of oxyha3moglobin 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 a're 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 HEMOGLOBIN or PURPLE CRUORIN 

 (STOKES 2 ), occurs only in very small quantities in arterial blood, in larger 

 quantities in venous blood, and is nearly the only blood-coloring matter 

 after asphyxiation. 



Haemoglobin is much more soluble than the oxyhaemoglobin, and 

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

 crystals are as a rule isomorphous with the corresponding oxyhaemoglobin 

 crystals, but are darker, having a shade toward blue or purple, and are 

 decidedly more pleochromatic. The haemoglobin from horse-blood has 

 also been obtained by UHLIK 3 in hexagonal six-sided plates. Its solu- 

 tions in water are darker and more violet or purplish than solutions of 

 oxyhsemoglobin of the .same concentration. They absorb the blue and 

 the violet rays of the spectrum in a less marked degree, but strongly 

 absorb the rays lying between C and D. In proper dilution the solu- 

 tion shows a spectrum with one broad, not sharply defined band between 

 D and E, whose darkest part corresponds to the wave-length ^ = 559. 

 (Spectrum pla.te 2.) This band does not lie in the middle between D 

 and E, but is toward the red end of the spectrum, a little over the line 



D. A haemoglobin solution actively absorbs oxygen from the air and is 

 converted into an oxyhaemoglobin solution. 



A solution of oxyhsemoglobin may be easily converted into a solution 

 having the spectrum of haemoglobin by means of a vacuum, by passing an 

 indifferent gas through it, or by the addition of a reducing substance, as, 

 for example, an ammoniacal ferrous-tart rate solution (STOKES' reduction 

 liquid). If an oxyhaemoglobin solution or arterial blood is kept in a 

 sealed tube, we observe a gradual consumption of oxygen and a reduction 

 of the oxyhaemoglobin into haemoglobin. If the solution has a proper 

 concentration, a crystallization of haemoglobin may occur in the tube at 

 lower temperatures (HtiFNER 4 ). 



1 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. 270; also Schuur- 

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

 f. Physiol., 3. 



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



3 Pfluger's Arch., 104. 



4 Zeitschr. f. physiol. Chem., 4; see also Uhlik, 1. c. 



