III.] COAGULATION OF BLOOD. 51 



in the following manner the coagulation of 

 albumin and globulin by heat. The white of 

 egg contains a small quantity only of globulin. 

 Place a test-tube containing 10 c.c. of the fluid 

 in a water-bath at about 50 C. and heat the 

 bath not too slowly up to about 80 0. Note on 

 a thermometer placed in the bath or in the 

 test-tube the temperature at which coagulation 

 begins (fluid slightly milky) and that at which 

 coagulation is complete (precipitate with clear 

 fluid). If the fluid is very slowly heated the 

 coagulate may be small owing to the formation of 

 alkali albuminate (cp. Lesson IX. 16) ; to avoid 

 this the serum should be carefully neutralized 

 with acetic acid before dilution. 



18. Add 2 c.c. of serum drop by drop to about 100 c.c. 

 of water in a glass beaker. A faint cloudy 

 precipitate of globulin, which is insoluble in 

 water, will be seen (cp. Lesson IX. 14). 



DEMONSTRATIONS. 



1. Coagulation of blood over mercury without 

 access of air. 



2. Fluidity of blood in living blood-vessels. 



3. Coagulation of blood within the vessels during 

 life on foreign bodies or in injured blood-vessels. 



4-2 



