THE BLOOD. 33 



Notice : 



a. The clot. What is its color, shape, size, consistency, 

 and position ? 



b. The serum or straw-colored liquid. Where is it 

 found? Compare it with the clot in quantity. Remove 

 the serum and notice the effect on the clot. 



II. FlBKIN. 



Beat vigorously the remainder of the blood obtained of 

 the butcher, with a bundle of twigs or wires, for a few 

 minutes until some stringy elastic fibrin has collected upon 

 them. Remove the twigs with the fibrin, rinsing them as 

 much as possible in the whipped blood. 



Notice : 



a. The amount, form, and nature of the fibrin. Whence 

 did it come ? 



b. What is its color? Rinse thoroughly under the 

 faucet and note again the color. To what was the former 

 color due? Compare with the color of clot in clotted 

 blood. Inferences. 



c. The liquid which remains after the fibrin has been 

 removed. What part of the blood is it? What color 

 is it? 



d. Allow this liquid to stand for some time. Does it 

 clot? To what, then, was the clotting in the other blood 

 due ? Compare this liquid carefully with the serum. 



III. THE COMPOSITION OF BLOOD SERUM. 



Material. Blood serum left after I. 



Apparatus. Evaporating dish. Ring-stand. Wire gauze. Bun- 

 sen burner. Test-tube. 



