OXYGEN-COMBINATIONS OF HEMOGLOBIN. 



57 



A second oxygen-containing isomeric, but chemically more stable 

 crystallizable combination is methemoglobin, whose molecule contains 

 the same amount of oxygen as oxy hemoglobin, but in different ar- 

 rangement. Its spectrum closely resembles that of hematin in acid 

 solution (Fig. 15, 5). The band toward the red is the heaviest, while 

 the others are narrow and are in part designated as not characteristic. 



Demonstration. i. By oxidizing substances, such as ozone, potassium iodid, 

 chlorates, nitrates. 2. By reducing substances, such as nascent hydrogen and 

 pyrogallol. 3. By indifferent influences, such as prolonged heating or slow desic- 

 cation of the blood. Potassium permanganate, potassium ferrocyanid and ferri- 

 cyanid exert an intense effect, while nitrites transform the oxyhemoglobin into 



Red. Orange. 



Yellow. 



Green. 



Cyanid Blue. 



110 



Oxyhemoglobin 

 0.18 per cent. 



Oxyhemoglobin 

 0.18 per cent. 



Carbon-monoxid 

 hemoglobin. 



Gas-free or reduced 

 hemoglobin. 



Methemoglobin ; 



also hematin in 



acid solution. 



Hematin in 

 alkaline solution. 



Hemochromogen in 



alkaline solution; 



also reduced hematin. 



A a 



FIG. 15. The Various Absorption-spectra of Hemoglobin. In all of the spectra the various Fraunhofer lines 

 and a scale in millimeters are drawn. 



a mixture of methemoglobin and nitrogen-monoxid hemoglobin. Not alone 

 lake-colored blood, but also the hemoglobin of intact erythrocytes may be 

 transformed into methemoglobin, as, for instance, by potassium chlorate, 

 antifebrin and other substances, and also by intoxication with these sub- 

 stances. Often both conditions are present in combination. The occurrence 

 of methemoglobin in solutions in the blood-plasma of a poisoned individual is 

 designated methemo plasm ia, and the -occurrence of the methemoglobin in the pre- 



