54 



LABORATORY METHODS 



blood are haemoglobin, haematin, haematoidin. The 

 most important are the hemin, which can be demon- 

 strated by the following method : 



HUMAN BLOOD. 



1, Biconcave red blood cells; 2, red blood cells on edge; 

 3, spherical red blood cells; 4, red Hood cells after the ac- 

 tion of water; 5, leukocytes; 6, rouleaux. Crenated red 

 cells to left of the rouleaux. 



Obtain a drop of blood in the usual way, and apply 

 to it some salt solution and some acetic aicid; let the 

 whole dry for a few minutes. Examine with H. P. 



The red blood cells are derived from the mesoblast, 

 and are nucleated and colorless when first formed. 



