THE BLOOD 



245 



guinea-pig, and horse, with acetic or ethylic ether and then add a solution 

 i to 5 per cent., of ammonium oxalate. A drop of this mixture placed under 

 the microscope will show crystal formation in a very few minutes. 



Chemic Composition of Hemoglobin. By appropriate methods 

 hemoglobin can be obtained m a practically pure form, and when subjected 

 to a temperature of iooC. its water of crystallization is driven off, after 

 which it can be analyzed. In the subjoined table the results of several 

 analyses are given for 100 parts of hemoglobin. 



The percentage composition of hemoglobin is thus seen to vary slightly 

 in different animals, suggesting that there may be different kinds of hemo- 

 globin. The molecular composition is not known. On the assumption 

 that each molecule contains one atom of iron, Preyer suggested the following 

 empirical formula: C 600 H 980 N 154 O 179 S3Fe, with a molecular weight of 

 *3>33 2 ; Jaquet has suggested a different formula: C 758 H 1203 N 195 O 218 S3Fe, 

 with a molecular weight of 16,669. It is verv evident from this that the 

 molecule is of enormous size and exceedingly complex. 



Quantity of Hemoglobin. The quantity of hemoglobin in blood as 

 determined by chemic, chromometric, and spectro-photometric methods 

 amounts to about 14 per cent, in man and 13 per cent, in woman. Of the 

 chemic methods, that based on the amount of iron is the one generally 

 employed. Chemic analysis has shown that hemoglobin contains 0.33 per 

 cent, and blood 0.046 per cent, of iron; with these two factors the quantity 

 of hemoglobin can be determined by the following formula: #= I00 ^ 46 = 

 14 per cent. The total quantity of hemoglobin in the blood, assuming 

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

 kilos) will therefore amount to 515 grams; e.g., x= 368 ** 14 =515. The 

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



vz. 



, ==I>7o 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 



