BLOOD. 75 



Note the character of the substance presented. It has 

 been obtained by whipping the blood before it has had time 

 to set in a solid mass. 



Apply three color protein tests. 



Recall the action of 0.2 per cent HC1, pepsin, and trypsin 

 upon fibrin. 



FORM ELEMENTS. 



These consist of the red blood cells, the leucocytes, and 

 the platelets. Chemically the solid matter of the red corpus- 

 cles consists of 90 per cent hemoglobin, 8 per cent proteins 

 and nucleins, and the remainder cholesterol, lecithin, and 

 inorganic salts. The predominating base of these salts is 

 potassium. 



The leucocytes, being typical animal cells, contain those 

 substances which are intimately connected with the term 

 protoplasm. Such are proteins (especially nucleoproteins), 

 lecithins, cholesterols, fats, carbohydrates, inorganic salts, 

 and water. Little is known concerning the composition of 

 the blood-platelets. They probably contain a protein of the 

 globulin type and a nucleoprotein. 



OXYHJEMOGLOBIN. 



Oxyhaemoglobin or haemoglobin belongs to the class of 

 conjugate proteins often spoken of as the respiratory pig- 

 ments, and forms the most important constituent of the 

 form elements. When its watery solution is heated to 70 C 

 it decomposes with the formation of an iron-containing pig- 

 ment, hcematin, and an albuminous body, globin. 



The function' of the oxyhremoglobin is that of an oxygen 

 carrier. The compound holds the oxygen in a rather loose 

 combination, and in all probability the iron of the hsematin 

 molecule is directly concerned in the process. This instability 



