III.] COAGULATION OF BLOOD. 45 



4. Place a small drop of fresh blood on a piece of 

 glazed neutral litmus paper, in about ten seconds 

 wipe off the drop, a blue spot will be left showing 

 that the blood is alkaline. Test also the reaction 

 of serum. 



5. Apply the Xanthoproteic and Millon's test for 

 proteids (cp. 16) to fibrin chopped up and 

 suspended in water. 



G. Take two test-tubes and in each place a few 



flocks of fibrin. 



a. Add water and place in water bath at about 

 39 C. for a day ; the fibrin does not dissolve 

 (it thus differs from albumin and peptone). 



1). Treat similarly but with dilute (1 p. c.) solu- 

 tion of sodic chloride; the fibrin does not 

 dissolve (it thus differs from globulin). 



7. Place two or three flocks of fibrin in a test-tube 

 containing a few c. c. of '2 p. c. HC1, the fibrin 

 soon swells up and becomes transparent; neu- 

 tralize the acid with Na 2 CO 3 , the fibrin shrinks 

 to its original size. If the fibrin is warmed with 

 the acid, solution slowly takes place, acid-albu- 

 min being formed (cp. Lesson IX.). 



8. Examine the plasma of horse's blood kept, by 

 means of cold, from coagulating 1 . 



1 The blood is allowed to run from the animal into a tall narrow 

 vessel contained in a much larger one packed with ice, a little salt 

 may be mixed with the ice, but of course not enough to reduce tho 

 temperature so much that the blood is frozen; sometimes also a vessel 



