THE BLOOD. 245 



the latter to be about 3684 grams (one-nineteenth of the body-weight, 70 

 kilos) will therefore amount to 491 grams; e.g., # = 3684 i * o I3 ' 3 = 49i. The 

 total amount of iron in the blood is obtained by the following formula: 

 viz., * = 3684 *- s6 =2.o6 grams. 



Clinic Methods for the Determination of the Percentage of Hemo- 

 globin. Under normal physiologic conditions the percentage of hemo- 

 globin undergoes but slight variation. In pathologic states there is fre- 

 quently a great diminution in the amount, especially in chlorosis, splenic 

 leukemia, and pernicious anemia, diseases in which it diminishes to a con- 

 siderable per cent, in many instances. For clinic purposes it becomes a 

 matter of importance to have some method by which the diminution of 

 hemoglobin can be determined. In the various methods employed the 

 normal amount of hemoglobin is considered as 100 per cent, and the normal 

 number of red corpuscles, 5,000,000 per cubic millimeter, is also considered 

 as 100 per cent, tinder such conditions the corpuscles have a normal color 

 known as the color index. This is expressed by a fraction of which the 

 percentage of hemoglobin is the numerator and the percentage of corpuscles 

 the denominator. The normal color index is therefore i or unity. In 

 some pathologic states the hemoglobin alone diminishes, the number of the 

 corpuscles remaining the same; in this instance the color index is less than 

 unity, e.g., if the hemoglobin be reduced to 80 per cent., as determined by the 

 method to be described, then the color index will be T 8 o F = o.8 which indicates 

 that each corpuscle retains but eight-tenths of the normal amount of hemo- 

 globin, or stated in the reverse way, each corpuscle has lost two-tenths of the 

 normal amount of its hemoglobin. In other pathologic states there is both 

 a diminution in the percentage of the hemoglobin and in the percentage of 

 the corpuscles and the diminution may be equal or unequal in degree. If 

 the diminution be equal the color index is unity; if it be unequal the color 

 index is less or greater than unity; e.g., if the percentage of hemoglobin be 

 but 60 and the percentage of red corpuscles, as determined by the method 

 of counting be but 80 (4,000,000 per cubic millimeter) then the color index 

 is |-J- = o. 7 5 which indicates that each corpuscle retains but three-fourths 

 of the normal amount of hemoglobin; if on the contrary the percentage of 

 hemoglobin be but 60, -and the percentage of red corpuscles be but 50 then 

 the color index is 1.2 which indicates that each corpuscle contains a larger 

 percentage of hemoglobin than normally. This condition is sometimes 

 observed in pernicious anemia. 



For the determination of these variations in the hemoglobin for clinical 

 purposes two chromometric methods are at present largely employed, that 

 of Gowers and v. Fleischl. All chromometric methods are based on the 

 principle that if two equally thick and equally well-illuminated solutions 

 present the same intensity of color, their richness in coloring-matter is the 

 same. There are two methods by which this can be done: (i) By diluting 

 the blood to be examined with water until the shade of color corresponds 

 to that of a solution of hemoglobin of known strength (Gowers). (2) 

 Diluting a given quantity of blood with a given quantity of water and then 

 finding an identical color which represents a previously determined quantity 

 of hemoglobin (v. Fleischl). 



