402 BLOOD AND LYMPH. 



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; O, 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 (Kuster). 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 750 grams of hemoglobin, 

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

 giving a total superficial area of about 3200 square meters. Practi- 

 cally 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 capillaries, 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 circulating through the lungs, therefore, 

 each corpuscle becomes exposed more or less completely to the action 

 of the air, and the utilization of the entire quantity of hemoglobin 

 must be nearly perfect. It may be worth while to call attention to 

 the fact that the biconcave form of the red corpuscle increases 

 the superficies of the corpuscle and tends to make the surface 

 exposure of the hemoglobin more complete. Instruments known 

 as hemometers or hemoglobinometers have been devised for clinical 

 use in determining the amount of hemoglobin in the blood of 

 * "Die Blutkrystalle." Jena, 1871. 



