214 



VETERINARY PHYSIOLOGY 



ment known as hsematoidin, which is really the same as 

 bilirubin. 



Hsemin the hydrochloride of hsematin is formed when 

 blood is heated with sodium chloride and glacial acetic 

 acid. It crystallises in small steel-black rhombic crystals, 

 and its formation is sometimes used as a test of blood stains. 

 ( Chemica I Physiology. ) 



The following table shows the relationship of these pigments 

 to one another : 



RELATIONSHIP OF HB AND ITS DERIVATIVES. 

 Methsemoglobin Hb0 2 HbCO 



Hb 



Hsematin 



Globin 



Acid Hsematin 



Alkaline Hsematin 



^Contain Iron. 



Oxidised Reduced 



(Hsemochromogen). 



Iron-free Hrematin Hsematoidin 

 (Hsematoporphyrin) Bilirubin 



Iron-free. 



IV. Gases of the Blood 



The muscles and other active tissues are constantly con- 

 suming oxygen and constantly giving off carbon dioxide. 

 The oxygen must be brought to the tissues by the blood, 

 and the carbon dioxide carried away by the same medium. 



Various methods of carrying out the examination of the 

 gases of the blood have been devised, and many different gas 

 pumps have been invented in which the gases may be col- 

 lected in the Torricellian vacuum over mercury. Haldane and 

 Barcroft have devised a convenient method, which depends 

 upon the fact that the oxygen can be driven off from blood 

 treated with dilute ammonia by the addition of potassium 



