EXPERIMENTS 133 



EXPERIMENTS AND DEMONSTRATIONS 



Materials: Alcohol; nitric acid; defibrinated blood; blood 

 clot or fresh liver; serum; chisel-pointed needle; test tubes; 

 blotting paper; microscope with powers up to 450; 2 fruit jars; 

 bundle of twigs or wires ; tumbler ; platinum foil ; alcohol lamp 

 or Bunsen burner. 



1) Get a drop of blood from lobe of ear or side of finger by 

 rubbing vigorously, washing with a little alcohol, and piercing 

 when dry to a depth of l /$ in. with a needle sharpened to a 

 chisel point, soaked in alcohol, and dried. (No pain results 

 from piercing.) Spread a drop of blood on a piece of glass, 

 put on a cover glass, and examine under microscope. Note 

 form, size and color of red blood, corpuscles ; method of cluster- 

 ing; color, form, size and relative number of white blood 

 corpuscles. 



2) Obtain a large drop of blood as above (1) described. 

 Note its physical characteristics (color, opacity, etc.) when it 

 flows from the wound ; its apparent change of color when it is 

 spread very thin on the glass and held over a sheet of white 

 paper; its color when mixed with a teaspoonful or more of 

 water in a test tube ; its change of consistency when a drop of 

 nitric acid is added and test tube is heated. 



3) Place another large drop of blood on a clean glass plate. 

 To prevent its drying, cover by inverting over it a glass lined 

 with wet blotting paper. 



In 4 or 5 minutes, remove glass and note condition of blood 

 when manipulated with a needle. 



Replace moist glass and in half an hour examine again. 



Additional Demonstrations at Option of Teacher: 



1) Collect blood at butcher's in a glass jar; set aside until 

 blood clots and carry without shaking. Observe clot and serum 

 next day. Carefully pour off serum for subsequent tests. 



2) Collect fresh blood in a pail and beat it vigorously with 

 twigs for 3 or 4 minutes. Note quantity of stringy elastic 

 material (fibrin) collected on twigs. 



Wash fibrin thoroughly in running water and note its color. 



3) Take some of serum and note its physical characteristics. 



