BLOOD-PIGMENTS. 269 



of the blood-corpuscles hcemochrom, are of a similar opinion. Since the 

 above-mentioned combinations of the blood-coloring matters with other 

 bodies, for example (if they really do exist) with lecithin, have not been 

 closely studied, the following statements will apply only to the free pig- 

 ment, the hemoglobin. 



The color of the blood depends in part on hemoglobin and in 

 part on a molecular combination of this substance with oxygen, 

 the oxyhcemoglobin. We find in blood after asphyxiation almost 

 exclusively haemoglobin, in arterial blood disproportionately large 

 amounts of oxyhaemoglobin, and in venous blood a mixture of 

 both. Blood-coloring matters are also found in striated as well 

 as in certain smooth muscles, and lastly in solution in different 

 invertebrates. The quantity of haemoglobin in human blood may 

 indeed be somewhat variable under different circumstances, but 

 amounts to about 14 per cent on an average, or 8.5 grams for each 

 kilo of the weight of the body. 



Haemoglobin belongs to the group of compound proteins, and yields 

 as cleavage products, besides very small amounts of volatile fatty acids 

 and other bodies, chiefly a protein globin, and a coloring-matter, hcemo- 

 chromogen (about 4 per cent), containing iron, which in the presence of 

 oxygen is easily oxidized into h&matin. 



As first shown by SCHUNCK and MARCHLEWSKI, and especially by the 

 work of the latter, a close relation exists between chlorophyll and 

 the blood-pigment, because a derivative of the first, phylloporphyrin, 

 stands very close in certain respects to a derivative of the blood-pigment 

 haematoporphyrin. By the investigations of NENCKI in conjunction with 

 MARCHLEWSKI and ZALESKI, J it was shown that haemopyrol could be 

 prepared from the derivatives of both the leaf-pigment and the blood- 

 pigments by reduction. The fact that chlorophyll and blood-pigments 

 are closely related and are constructed from the same mother-substance, 

 is of the greatest biological importance. 



The haemoglobin prepared from different kinds of blood has not 

 exactly the same composition, which seems to indicate the presence 

 of different haemoglobins. The analyses by different investigators of 

 the haemoglobin from the same kind of blood do not always agree with 

 one another, which probably depends upon the somewhat varying methods 

 of preparation. The following analyses are given as examples of the 

 constitution of different haemoglobins : 



1 Schunck and Marchlewski, Annal. d. Chem. u. Pharm., 278, 284, 288, 290; NenckL 

 Ber. d. deutsch. chem. Gesellsch., 29; Marchlewski and Nencki, Ber. d. d. chem, 

 Gesellsch., 34; Nencki and Zaleski, ibid.; Marchlewski, Chem. Centralbl., 1902, I, 

 1016; Zaleski, Zeitschr. f. physiol. Chem., 37. 



