COLORING MATTERS. 97 



has also been discovered in the blood of the pond-snail, the horse-leech, 

 and the fresh-water shrimp. 



Functional Activity and Changes of Hemoglobine in the Body. 

 Hemoglobine is the most active of all the coloring matters in the 

 animal system. It absorbs oxygen from the air in the lungs, and thus 

 provides an incessant supply for the whole body. But this absorption 

 is not a process of oxidation. The oxyhemoglobine holds its oxygen 

 in loose combination, and readily parts with it in the general circula- 

 tion, returning to the state of reduced hemoglobine in the venous blood. 

 Each of these two properties is equally important with the other, for it 

 i> by this means that the oxygen of the lungs finds its way into the 

 >ystem at large. 



A marked feature in the chemical constitution of hemoglobine is that 

 it contains iron. This fact is the more important because it is the only 

 substance in the animal body, excepting hair, which contains iron in 

 any considerable amount, and because iron is also requisite for the for- 

 mation of the green coloring matter of plants. Experiment has shown 

 that without iron vegetation cannot go on ; and there is reason to 

 believe that it is equally essential to the constitution of the animal 

 coloring matter, and thus indirectly to the general nutrition of the 

 animal body. It is present in hemoglobine, in all probability, not in 

 the form of a distinct oxide, but directly combined, like sulphur, with 

 the carbon, hydrogen, nitrogen, and oxygen which form the remainder 

 of its substance. 



One thousand parts of hemoglobine contain 4.2 parts of iron ; and, 

 according to the average results obtained by different observers, healthy 

 human blood contains, per thousand parts, 123.4 parts of hemoglobine, 

 and 0.52 parts of iron. The human body, according to the lowest 

 authentic estimate, contains 8 per cent, of its weight of blood, which 

 would give, for a man weighing 65 kilogrammes, 2.71 grammes of iron 

 in the blood of the whole body. 



The iron of the hemoglobine passes out by the bile and the urine, 

 both of which contain traces of its presence. It is also contained in 

 the hair, where it forms nearly 7 per cent, of the incombustible ingre- 

 dients. It is supplied to the body by ordinary food, in which it is 

 always present in appreciable amount. Since hemoglobine exists to 

 some extent in the muscular tissue, it will be present in a more or less 

 altered form, but still containing iron, in most kinds of animal food. 

 According to the analyses of Moleschott, 500 grammes of beef (about 

 one pound avoirdupois) will contain 0.035 gramme of iron ; and it is 

 found in even larger proportion in rye, barley, oats, wheat, peas, and 

 especially in strawberries. As the quantity of this substance discharged 

 daily in the urine and the bile is so small, we must regard the greater 

 portion of that which passes through the system as used in the growth 

 of the hair; and a very moderate amount in the food is sufficient for 

 the requirements of nutrition. 



G 



