34 PHYSIOLOGY FOE THE LABORATORY. 



a. Allow any corpuscles that remain in the serum to 

 settle and pour off some of the clear liquid. Evaporate 

 this slowly to dryness. 



1. How much residue is left? What does this 



represent ? 



2. Heat this residue as you did the bone until it is 



all burned. Is anything left? What kind 

 of matter is it? 



3. Moisten a piece of paper with serum and attempt 



to dry it. What must have been present in 

 the serum ? Whence did it come ? 



4. Boil a small amount about 10 c.c. of serum in a 



test-tube. What change takes place ? What 

 does this show? 



C. The Influence of the Presence or Absence of Oxygen on 

 the Color of Blood. 



Material. Fresh blood in a small test-tube. The blood that was 

 left after experiment B may be used. 



Apparatus. A small test-tube. A piece of glass tubing six 

 inches long. 



Collect a small amount of blood in a test-tube. 



a. What color is the blood ? 



b. Is it arterial or venous ? 



c. Breathe through a glass tube into the blood. 



d. What occurs ? Explain. 



