136 THE BLOOD 



Of the inorganic salts of the corpuscles, the iron omitted, there are present, 

 in 100 parts of corpuscles (Schmidt): 



Potassium chloride 0.3679 per cent. 



Potassium phosphate o . 2343 per cent. 



Potassium sulphate 0.0132 per cent. 



Sodium phosphate 0.0633 P er cent. 



Calcium phosphate 0.0094 per cent. 



Magnesium phosphate o .0060 per cent. 



Soda 0.0341 per cent. 



0.7282 



Hemoglobin. Of the substances in the erythrocytes, by far the most 

 important from every point of view is the pigment, hemoglobin. It composes 

 about 90 per cent, of the total solids of the corpuscles; therefore, between 

 14 and 15 per cent, of the blood itself. Hemoglobin is the most complex 

 compound in the body, having a molecule of the enormous molecular weight 

 of 16,669. Hemoglobin is intimately distributed throughout the stroma of 

 the corpuscle, and when dissolved out it can be crystallized. 



Its percentage composition is ,53.85; H, 7.32; N, 16.17; O> 21.84; $,0.63 

 Fe o . 42. Jacquet gives the empirical formula for the hemoglobin of the dog, 

 C758H 1205 N 195 S 3 FeO 218 . The most interesting of the properties of hemo- 

 globin are its powers of crystallizing and its attraction for oxygen and other 

 gases under certain pressure relations. 



Hemoglobin Crystals. The hemoglobin (oxyhemoglobin) of the blood of 

 various animals possesses the pow r er of crystallizing to very different ex- 

 tents. In some the formation of crystals is almost spontaneous, whereas 

 in others it takes place either with great difficulty or not at all. Among 

 the animals whose blood coloring- matter crystallizes most readily are the 

 guinea-pig, rat, squirrel, and dog; and in these cases to obtain crystals it 

 is generally sufficient to dilute a drop of recently drawn blood with water 

 and to expose it for a few minutes to the air. In many instances other means 

 must be adopted; e.g., the addition of alcohol, ether, or chloroform, rapid 

 freezing and then thawing, the application of an electric current, a tempera- 

 ture of 60 C., the addition of sodium sulphate, or the addition of decom- 

 posing serum of another animal. 



The hemoglobin of human blood crystallizes with difficulty, as does also 

 that of the ox, the pig, the sheep, and the rabbit. 



The forms of hemoglobin crystals, as will be seen from figures 119 and 

 120, differ greatly. Hemoglobin crystals are soluble in water. Both the 

 crystals themselves and also their solutions have the characteristic color of 

 arterial blood. 



A dilute solution of oxyhemoglobin gives a characteristic appearance 

 with the spectroscope. Two absorption bands are seen between the solar 



