52 LABORATORY EXERCISES. 



blood is completely burned, and 

 what does this prove as to the 

 composition of serum? 



/. Warm some blood-serum in a test- 

 tube. What do you find on the 

 inner surface of the upper part of 

 the tube? What ingredient is 

 therefore present in blood in large 

 quantity? 



g. From the preceding experiments name 

 all the food materials you have 

 found present in blood-serum and 

 state those that are absent. 



B. Study of defibrinated blood. 



1. Describe the preparation of defibrinated 



blood (see Bottle No. 2 under Materials 

 above). 



2. What ingredient of blood has been re- 



moved? (See Bottle No. 3.) 



3. Where is this substance found in the clotted 



blood? 



4. What, therefore, is the effect of whipping 



blood, and why? 



5. Remove a piece of blood fibrin from bottle 



No. 3. 



a. What is its color? 



b. Pull it apart. Describe some of its 



characteristics. Is it elastic? 



c. Test a piece of blood fibrin with nitric 



acid and ammonia. What do you 

 conclude as to its composition? 



C. Change in blood after mixing with oxygen. 



