96 



COLORING MATTERS. 



HEMOGLOBINE CRYSTALS; from dog-faced 

 baboon. (Preyer.) 



Hemoglobine, both crystallized and in watery solution, has the clear 

 bright red color of arterial blood. It is distinguished beyond all other 



known ingredients of the 



Fig. 20. body, by its capacity for ab- 



sorbing oxygen, which it 

 retains in the form of a loose 

 combination. According to 

 the average result of various 

 experiments one gramme of 

 hemoglobine in watery solu- 

 tion will absorb 1.27 cubic 

 centimetres of oxygen. The 

 oxygen thus absorbed is 

 again given off under the in- 

 fluence of diminished pres- 

 sure, heat, or the continued 

 displacing action of hydro- 

 gen or nitrogen' gas. The 

 coloring matter is accord- 

 ingly known under two dif- 

 ferent forms, namely, that 

 of " oxidized" hemoglobine, 



containing an excess of loosely combined oxygen, and that of " reduced" 

 hemoglobine, in which the surplus oxygen has been removed. The color 

 of hemoglobine varies according to these two conditions, being bright 

 red in the oxidized form, and dark purple when deoxidized. The 

 presence of hemoglobine in either one of these two conditions is the 

 cause of the color of arterial and venous blood. 



A marked feature in the chemical constitution of hemoglobine is that 

 it contains iron. This fact is the more important because it is the only 

 ' substance in the animal body, excepting hair, which contains iron in 

 any considerable amount, and because iron is also an indispensable 

 requisite for the formation of the green coloring matter of plants. 

 Experiment has shown that without the presence of iron vegetation 

 cannot go on ; and there is every reason to believe that iron is equally 

 essential to the constitution of the animal coloring matter, and thus 

 indirectly to the general nutrition of the animal body. It is present 

 in hemoglobine, in all probability, not in the form of a distinct oxide, 

 but directly combined, like sulphur, with the carbon, hydrogen, nitro- 

 gen, and oxygen which form the remainder of its substance. 



One thousand parts of hemoglobine contain 4.2 parts of iron ; and, 

 according to the average results obtained by different observers, healthy 

 human blood contains, per thousand parts, 123.4 parts of hemoglobine, 

 and 0.52 part of iron. This would give, for a man weighing 65 kilo- 

 j grammes, 2.82 grammes of iron, as contained in the blood of the whole 

 body. 



The iron of the hemoglobine passes out of the body by the bile and 



