276 THE BLOOD. 



and nuclein, 12.24 ; hemoglobin, 86.79 ; lecithin, 0.72 ; cholesterin, 

 0.25. The nucleoproteid is called by some writers cell-globulin. 

 The inorganic substances are potassium and sodium salts ; potas- 

 sium constituting 40.89 per cent, of the total ash, while of sodium 

 there is only 9.71 per cent. 



Hemoglobin. This is the term applied to the highly complex, 

 iron-containing, crystalline coloring-matter, which forms the most 

 important constituent of the colored corpuscles of the blood, and 

 by virtue of which they perform their function as the oxygen- 

 carriers of the organism (Gamgee). It constitutes 95 per cent, of 

 the solid matter of the red corpuscles, and in the adult male there 

 are about 14 grams for each 100 grams of blood, or in all about 

 750 grams. When united with a molecule of oxygen it forms 

 oxyhemoglobin ; when it exists by itself, without this molecule, it 

 bears the name of hemoglobin or reduced hemoglobin. Because of 

 its property of serving as an oxygen-carrier it is spoken of as a 

 respiratory pigment. The hemoglobin in the blood of different 

 animals varies both physically and chemically, so that some writers 

 speak of the hemoglobins; but Gamgee thinks this is unnecessary 

 and misleading, inasmuch as the proportion in which iron, the 

 characteristic element in the blood coloring-matter, occurs, is 

 absolutely the same in many animals ; and, besides, there is abun- 

 dant evidence in favor of the view that the optical and physiologic 

 properties of hemoglobin depend upon the identical " typical 

 nucleus" in all animals. 



When hemoglobin is decomposed in the presence of oxygen, 

 it breaks up into a proteid, globulin, which constitutes 96 per 

 cent, of it, and hematin, of which there is 4 per cent. If this 

 decomposition takes place without oxygen, instead of hematin, 

 hemochromogen re produced. It is to this latter substance that 

 hemoglobin owes its characteristic property of taking up oxygen. 



The exact percentage-composition of the hemoglobin of human 

 blood has not been determined ; that of the dog, as analyzed by 

 Jaquet, is as follows : C, 53.91 ; H, 6.62 ; N, 15.98; 8,0.542; 

 FeO, 0.333 ; O, 22.62. The molecular formula is C 758 H 1203 N 195 - 

 833, FeO 218 , making the molecular weight 16.669. Gamgee has 

 calculated for the hemoglobin of the ox the following : C 759 H 1208 - 

 N 2lo S 2 FeO 204 . Bunge says, in reference to the molecular weight 

 of hemoglobin : " The enormous size of the hemoglobin-molecule 

 finds a teleological explanation, if we consider that iron is eight 

 times as heavy as water. A compound of iron which would float 

 easily along with the blood-current through the vessels could only 

 be secured by the iron being taken up by so large an organic 

 molecule." Hemoglobin forms crystals in the absence of oxygen. 



Hemoglobinometers. There have been various methods devised 

 to determine the amount of hemoglobin in the blood. Those which 

 are commonly used are sufficiently exact for clinical purposes, 



