36 CHLOROPHYLL 



Haemoglobin 



In this animal kingdom there is a pigment which may con- 

 test with Chlorophyll the title of being the most interesting 

 material known. That pigment is haemoglobin. It is a much 

 more complex substance than chlorophyll, being a compound 

 of the pigment proper — haematin — with a protein giobin. 



To this pigment the higher animal creation, as we know it, 

 owes its existence. The life of the mammal, as compared with 

 that of the jelly-fish, is one of intensive oxidation. Intensive 

 oxidation imjDlies extensive oxygen supply and extensive 

 oxygen supply can only be furnished to tissues far removed 

 from the atmosphere by an efficient system of transport. Such 

 a system is furnished by haemoglobin and there is no other 

 material capable of playing the same role with equal success. 

 Owing to its presence a given quantity of blood can take up 

 seventy times as much oxygen as would otherwise be the 

 case, and, what is almost more remarkable, the properties of 

 haemoglobin and those of the human body are so adjusted 

 that the oxygen is given up with the same facility in the 

 capillaries of the tissue as it is acquired in those of the lung. 

 The property of uniting with oxygen belongs to the haematin, 

 the property of giving it up in vacuo is conferred upon the 

 haematin by its union with giobin, as also is its great solubility. 



It is not a little remarkable that haematin and chloroj^hyll 

 have much in common from the chemical point of view. 



