428 BLOOD AND LYMPH. 



molecule of hemoglobin its valuable physiological properties as a 

 respiratory pigment, yet in the blood corpuscles this substance is 

 incorporated into the much larger and more unstable molecule of 

 hemoglobin, whose behavior toward oxygen is different from that 

 of the hematin itself, the difference lying mainly in the fact that 

 the hemoglobin as it exists in the corpuscles forms with oxygen a 

 comparatively feeble combination that may be broken up readily 

 with liberation of the gas. 



Hemoglobin is widely distributed throughout the animal king- 

 dom, being found in the blood corpuscles of mammalia, birds, 

 reptiles, amphibia, and fishes, and in the blood or blood corpuscles 

 of many of the invertebrates. The composition of its molecule is 

 found to vary somewhat in different animals; so that, strictly 

 speaking, there are probably a number of different forms of hemo- 

 globin all, however, closely related in chemical and physiological 

 properties. Elementary analysis of dogs' hemoglobin shows the 

 following percentage composition (Jaquet) : C, 53.91; H, 6.62; N, 

 15.98; S, 0.542; Fe, 0.333; 0, 22.62. Its molecular formula is 

 given as C 758 H 1203 N 195 S 3 FeO 218 , which would make the molec- 

 ular weight 16,669. Other estimates are given of the molecular 

 formula, but they agree at least in showing that the molecule is of 

 enormous size. The hematin that is split off from the hemoglobin 

 is a pigment whose constitution is relatively simple, as is indicated 

 by its percentage formula, C 34 H 34 N 4 FeO 5 (Kiister). It contains 

 all of the iron of the original hemoglobin molecule. Gamgee has 

 called attention to two facts which seem to indicate that the globin 

 and hematin do not exist as such in the hemoglobin molecule. 

 Thus, hematin is magnetic, that is, is attracted by a magnet, while 

 hemoglobin, on the contrary, is diamagnetic. Globin alone rotates 

 the plane of polarized light to the left, levorotatory, while hemo- 

 globin solutions are dextrorotatory. The exact amount of hemo- 

 globin in human blood varies naturally with the individual and with 

 different conditions of life. According to Preyer,* the average 

 amount for the adult male is 14 grams of hemoglobin to each 100 

 grams of blood. It is estimated that in the blood of a man weighing 

 68 kilograms there are contained about 500 to 700 grams of hem- 

 oglobin, which is distributed among some 25,000,000,000,000 of 

 corpuscles, giving a total superficial area of about 3200 square 

 meters. Practically all of this large surface of hemoglobin is 

 available for the absorption of oxygen from the air in the lungs, 

 for, owing to the great number and the minute size of the capil- 

 laries, the blood, in passing through a capillary area, becomes 

 subdivided to such an extent that the red corpuscles stream 

 through the capillaries, one may say, in single file. In circu- 

 lating through the lungs, therefore, each corpuscle becomes 

 * "Die Blutkrystalle," Jena, 1871. 



