OXYHAEMOGLOBIN. 279 



tt . ? /3-, 7- and S-oxyhsemoglobin, all having the same absorption-spectrum, and 1 

 gram combining with respectively 0.4, 0.8, 1.7, and 2.7 cc. oxygen at the tem- 

 perature of the room and with an oxygen pressure of 150 mm. mercury. The 

 7-oxyha3moglobin is the ordinary one obtained by the customary method of 

 preparation. BOHR designates as a-oxyhsemoglobin the crystallin powder 

 obtained by drying 7-oxyhaemoglobin in the air. On dissolving a-oxyhsemo- 

 globin in water it is converted into jS-oxyhsemoglobin without decomposition, 

 and the quantity of iron is increased. On keeping a solution of 7-oxyha3moglobin 

 in a sealed tube it is transformed into S-oxhyaamoglobin, although the exact 

 conditions under which this change takes place are not known. According to 

 HUFNER J these are nothing but mixtures of genuine and partly decomposed 

 haemoglobins. 



The ability of haemoglobin to take up oxygen seems to be a function 

 of the iron it contains, and when this is calculated as about 0.33-0.40 

 per cent, then 1 atom of iron in the haemoglobin corresponds to about 

 2 atoms or 1 molecule of oxygen. By increasing the partial pressure as 

 well as by increasing the quantities of oxygen, the haemoglobin in solu- 

 tion takes up more oxygen, until it is completely saturated, when 1 mole- 

 cule of haemoglobin is combined with 1 molecule of oxygen. With reduced 

 oxygen pressure a dissociation must naturally take place and oxygen 

 is given off, and a re-formation of haemoglobin takes place, and this makes 

 it possible to expel completely the oxygen from an oxyhaemoglobin solu- 

 tion or blood by means of vacuum, or by passing an indifferent gas 

 through the solution. The equilibrium between oxyhaemoglobin, haemo- 

 globin, and oxygen depends, therefore, according to HUFNER, upon 

 a mass action, corresponding to the formula Hb-f-C^^HbCV BoHR 2 

 has arrived at the conclusion that not only a double dissociation takes 

 place, in which a dissociation of the oxygen-iron combination in the 

 oxyhaemoglobin occurs, but also a dissociation of the haemoglobin 

 into a ferruginous as well as into a non-ferruginous part. Correspond- 

 ingly he has suggested another formula and hence the dissociation curves 

 for oxyhaemoglobin given by HUFNER and BOHR are different. 



Important investigations have recently been carried out on this 

 question by BARCROFT and his co-workers CAMIS and ROBERTS from 

 which it follows that a generally valid dissociation curve cannot be given, 

 as the curve direction is dependent upon the nature and concentration 

 of the salts present in the solution. A haemoglobin solution with the salts 

 of the blood-corpuscles of the dog gives a dissociation curve of dog-blood 

 while with the salts from human blood-corpuscles it gives a curve like 

 human blood. In the presence of salts the dissociation follows BOHR'S 

 formula, and on the contrary while a salt-free haemoglobin solution follows 

 the oxygen combination according to the mass-action law of HUFNER. 



1 Arch. f. (Anat. u.) physiol., 1894. 



2 Bohr, Centralbl. f. physiol., 17, pp. 682 and 688. 



