BLOOD PLATELETS 39 



after the coloring matter is dissolved out. The hemoglobin 

 is ensnared in the stroma. 



(b) White Blood Corpuscles or Leukocytes. 



General Description. The white blood corpuscles or leu- 

 kocytes are large, colorless, nucleated cells with no general 

 form, but which are capable of changing their form by ame- 

 boid movement. 



Number. The number of leukocytes varies from seven to 

 ten thousand per cubic millimeter. 



Function. The white corpuscles are not under the control 

 of the central nervous system, but are controlled by some 

 chemotaxic force. They are able to go and come by ame- 

 boid movement through the stromata of capillary walls and 

 wander here and there in the tissues. It is this that gives 

 them their name of wandering cells. 



White blood corpuscles are of importance from a physio- 

 logical standpoint, because of this ability to wander. They 

 can transfer undissolved substances from one part of the 

 body to another and can destroy and remove foreign sub- 

 stances and harmful microorganisms. 



The power they have of ingesting foreign substances is 

 called phagocytosis. They will migrate in large numbers 

 and surround a foreign object and endeavor to remove it 

 from the tissue. They have the power of liquefying tissue 

 and it is this liquefied tissue mixed with the dead bodies of 

 white corpuscles that is known as pus. 



(c) Blood Platelets. 



These are colorless discs about one-third to one-fourth the 

 size of red blood corpuscles. Some claim for them the full 

 value of blood cells, while others insist they are the nuclear 

 remains of destroyed leukocytes. There are about 635,000 



