24 6 TEXT-BOOK OF PHYSIOLOGY. 



The elementary composition of hemoglobin is thus seen to vary 

 slightly in different animals, suggesting that there may be different 

 kinds of hemoglobin. The rational molecular formula is not known. 

 On the assumption that each molecule contains one atom of iron, 

 Preyer suggested the following empirical formula: C 600 H 960 N 154 O 179 - 

 S 3 Fe, with a molecular weight of 13,332; Jaquet has suggested a 

 different formula: viz., C 758 H 1203 N 195 O2 18 S 3 Fe, with a molecular weight 

 of 16.669. It is very evident from this that the molecule is of enor- 

 mous size and exceedingly complex. 



Quantity of Hemoglobin. The quantity of hemoglobin in blood 

 as determined by chemic, chromometfic, and spectF6-f>n6Wllittric 

 method Aamounts to about 14 per cent, injnan and 13 jger^cenjLjn 

 womanM Of the chemic methods, that based on the amount of iron 

 isTKPmbst familiar. Chemic analysis has shown that hemoglobin 

 contains 0.43 per cent, and blood 0.056 per cent, of iron; with these 

 two factors the quantity of hemoglobin can be determined by the 

 following formula: x = I0 * - ^ = 13.33 P er cent - Tne tota l 

 quantity of hemoglobin in the blood, assuming the latter to be about 

 5 769 grams (one-thirteenth of the body- weight, 75 kilos) will therefore 

 amount to 769 grams; e. g., x = 576g * o 13 ' 33 = 769. The total amount 

 of iron in the blood is obtained by the following formula: viz., x = 



57656 = 





Under normal physiologic conditions the percentage of hemo- 

 globin undergoes but slight variation. In pathologic states there is 

 frequently a great diminution in the amount, especially in chlorosis, 

 splenic leukemia, and pernicious anemia, diseases in which it dimin- 

 ishes to 2 J per cent, in many instances. For the determination of 

 these variations in the hemoglobin for clinical purposes two chromo- 

 metric 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 pre- 

 sent 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 repre- 

 sents a previously determined quantity of hemoglobin (v. Fleischl). 



Gowers' hemoglobinometer consists (Fig. 102) of two glass tubes 

 of exactly the same size. One, A, contains glycerin jelly colored 

 with picro-carmine the shade of which corresponds to that of normal 

 blood diluted 100 times, 20 c.mm. in 2000 c.mm. of water repre- 

 senting a i per cent, solution. The other tube, B, is ascendingly 

 graduated with 120 divisions, each one of which corresponds to 20 



