CHAPTER VIII. 

 THE BLOOD AND THE LYMPH. 



The Blood. The blood is composed of a clear liquid, 

 the plasma, and the blood cells, or corpuscles. In a drop 

 of blood under the microscope the plasma occupies the 

 clear spaces between the corpuscles. The corpuscles 

 make up one third of the bulk of the blood, and the 

 plasma two thirds. 



Microscopic Examination of the Blood. To get a drop of blood 

 from the finger, wind a cord around the finger, beginning at the base, 

 drawing the cord moderately tight, until the last joint is reached. By 

 this time the end of the finger is usually well distended with blood. 

 With a clean needle make a quick, sharp, light puncture near the base 

 of the nail ; this ordinarily brings a drop of blood. Put a very small 

 drop on each of several slides and quickly cover with coverslips. 

 Examine with a high power. 



The Colored Corpuscles. These are often called the 

 red corpuscles. Although in the mass they give the blood 

 a red appearance, when seen singly they are faint yellow- 

 ish red. In shape they are seen to be circular disks, 

 hollowed on each side like a sunken biscuit. These cor- 

 puscles tend to gather side by side, in rolls, like coins. 

 Each colored corpuscle is a cell without a nucleus. 



The Colorless Corpuscles. In the open spaces between 

 the rolls of colored corpuscles may occasionally be found 

 some spherical corpuscles. They are often called the 

 white corpuscles. The colorless corpuscles are very numer- 



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