184 



THE BLOOD 



According to Jaquet, the molecular formula of hemoglobin is C758Hi 2 o3N 196 - 

 S 3 FeO 2 i8, with a molecular weight of 16.66 grams. Its molecule, therefore, is 

 extremely large and complex, a peculiarity which Bunge explains by saying that, 

 as iron is eight times as heavy as water, it must be united with a very large organic 

 molecule, otherwise it could not be floated by the blood. The p gment substance 

 hematin, on the other hand, possesses a relatively simple constitution, as may be 

 gathered from the following formula of Kuster, which reads: C 34 H3 4 



The Preparation and Quantity of Oxyhemoglobin. If blood is 

 laked and is then allowed to stand, the dissolved hemoglobin is de- 

 posited in time in the form of crystals. It is to be noted, however, that 



FIG. 103. HEMOGLOBIN CRYSTALS. (After O. Funke.) 



the speed with which they are formed varies considerably. Thus, 

 they appear very rapidly in the laked blood of the horse, dog and 

 guinea-pig, and especially if the sample of blood is cooled to - 10 C., 

 or if a small quantity of alcohol is added to it. The blood of the pig, 

 ox, or man yields them with much greater difficulty. Better results 

 may be obtained if the sample of blood is first diluted with an equal 

 quantity of a saturated solution of ammonium sulphate. The pre- 

 cipitate, which consists of globulins, is then filtered off and the filtrate 

 permitted to stand. The methods most commonly employed for 



