DECOMPOSITION OF HEMOGLOBIN HJEMATIN, ETC. 235 



is cut off. This spectrum, which is characteristic of reduced haemo- 

 globin, is replaced by two bands when the haemoglobin combines 

 with oxygen one broad baud in the green near E, and a narrow 

 one, more clearly defined, in the yellow close to the D line ; both 

 bands lie between D and E. With strong solutions the spectrum 

 is darkened at either extremity, and the two bauds become wider 

 and tend to fuse into one. (3.) Further, the oxygen may be re- 

 placed by other substances which unite with the haemoglobin. 

 One of the most important of these is carbonic oxide, which forms 

 a much more stable compound with haemoglobin than oxygen. 

 It is of a bright cherry-red color, and has two absorption bauds in 

 the spectrum very like those of oxyhaemoglobiu ; that in the yellow 

 is, however, removed a greater distance from the D line towards 

 the violet end. 



It is this compound which is formed in poisoning with carbonic 

 oxide. The CO occupying the place of the oxygen, thus destroys 

 the function of the blood corpuscles. CO-haemoglobin may be dis- 

 tinguished from O-haernoglobin by not being reduced by reagents 

 greedy of oxygen, and by the bright red color which appears when 

 10 per cent, solution of caustic soda is added, and the mixture 

 heated. O-haemoglobin gives a muddy brown color under the 

 same treatment. 



DECOMPOSITION OF HAEMOGLOBIN 



Haemoglobin may easily be broken up into two constituents 

 namely, (a) a colorless substance which is nearly related to the 

 class of proteids called globulin, and (b) a blackish red amorphous 

 material called Hcematin, which contains all the iron of the haemo- 

 globin. 



This change is brought about by whatever causes the coagula- 

 tion of albumin, such as the addition of acids, strong alkalies, and 

 heat to 70 C. 



H^EMATIN, ETC. 



Haematin is a secondary product, being the result of the oxida- 

 tion of a substance called haemochromogen, which is the first out- 

 come of the decomposition of the haemoglobin. Haemochromogen 



