144 BLOOD AND ITS IMPORTANCE 



II. Continue beating until no more fibrin can be removed. 



III. After beating, remove the fibrin, and pour the remainder of blood 

 into a bottle. Label it defibrinated blood. 



IV. Pour a like quantity of unbeaten blood into a second bottle and let 

 both volumes of blood stand, corked, for several days. Compare the appear- 

 ance of the materials in the two bottles. 



A. Describe any solid mass, a clot, which may have formed in one or 

 both bottles. 



B. Describe the liquid around the clot. This liquid is called serum. 

 Compare blood serum with defibrinated blood. 



V. Place an ounce of blood in a third bottle and, by means of a delivery 

 tube, add oxygen to it. 



A. What effect has oxygen on the color of blood? This is now oxy- 

 genated blood. It may be compared to arterial blood. 



VI. Place an ounce of blood in a fourth bottle and, by means of a delivery 

 tube, add carbon dioxide to it. 



A. What effect has carbon dioxide on the color of blood? This is 

 deoxygenated blood. It may be compared to venous blood. 



VII. Look at the veins in your wrist. 



A. Do veins appear to have oxygenated or deoxygenated blood in 

 them? 



B. Explain why blood which flows from a cut vein looks like oxy- 

 genated blood. 



Problem. Study of blood serum. 



Test the serum for protein, starch, sugar, fat, water, and mineral matter. 

 Account for the presence or absence of each. 



Problem. Study of blood corpuscles. 



Mount a tiny drop of blood on a glass slide. By means of the edge of a 

 square cover glass, smear the drop across the slide, making a thin film. Cover 

 with Wrights' Blood Stain for three minutes ; then wash off the stain. Exam- 

 ine with low power and then with high power of the microscope. Observe the 

 regular, disklike, yellowish cells which cling together ; when in masses of great 

 numbers they appear red. These are the red corpuscles. The larger, irregu- 

 lar, blue cells are the white corpuscles. When unstained, they are colorless. 



I. Estimate roughly, the proportionate number of the two types of cor- 

 puscles. 



