AMBOCEPTORS AND COMPLEMENTS. HEMOLYSINS 923 



(a) Explain the appearance of a positive reaction. 



(b) What constitutes a negative reaction? 



(c) What is the diagnostic value of this reaction in syphilis? 



(d) What other value has this reaction in diagnosis? 



(e) What relation does this reaction bear to total cell counts? 



(f) Explain the mechanism of the reaction. 



EXERCISE 27. AMBOCEPTORS AND COMPLEMENTS. HEMOLYSINS 



EXPERIMENT 69. RESISTANCE OF RED BLOOD-CORPUSCLES TO SALT 

 SOLUTION OF VARIOUS TONICITIES. NON-SPECIFIC HEMOLYSIS 



1. Arrange a series of twenty-three small sterile test-tubes in a rack; to each of 

 the first twenty-one tubes add 3 c.c. of various dilutions of salt solutions ranging 

 from 0.6 per cent, to 0.2 per cent, in steps of 0.02 per cent. Large amounts of these 

 solutions should be at hand, preserved in bottles fitted with tight cork stoppers to 

 prevent evaporation, or prepared at the time according to the technic given in the 

 text (page 402). To tube No. 22 add 3 c.c. distilled water and to No. 23 the same 

 amount of normal salt solution (0.85 per cent.). 



2. Secure blood-corpuscles after the method given in the text. Dog blood may 

 be substituted for human blood. After the final washing, add 0.05 c.c. to each tube. 

 Shake gently. 



3. Make a preliminary reading at once; the final reading is made after the tubes 

 have been standing hi the refrigerator overnight. 



4. Note the appearance of hemolyzed blood. Prepare a color scale by placing 

 1 c.c. blood-corpuscles in 30 c.c. distilled water, which represents a standard of 100 

 per cent, hemolysis. From this solution prepare dilutions with distilled water to 

 represent 80, 60, 40 and 20 per cent, hemolysis. For example, 4 c.c. of the stock 

 solution plus 1 c.c. distilled water equals 5 c.c. of an 80 per cent, solution; 3 c.c. of 

 the stock plus 2 c.c. water equals a 60 per cent, solution; 2 c.c. of stock plus 3 c.c. of 

 water equals a 40 per cent, solution, and so on. Carefully compare the volume of 

 non-hemolyzed cells in the bottom of some of the test-tubes with the amount of color 

 in the supernatant fluid. A Duboscq colorimeter may be used for making com- 

 parisons with the controls. 



5. Determine the minimal and maximal resistance of the corpuscle employed. 



(a) What is the appearance of hemolyzed blood? 



(b) What is the meaning of the term hemolysis? 



(c) Why is this called non-specific hemolysis? 



(d) What does a normal salt solution mean? 



(e) What is the importance of using a normal salt solution in hemo- 

 lytic experiments? 



(f) How is hemolysis produced by hypotonic solutions? 



(g) What would be the objections of using a hypertonic salt solution? 

 (h) How is an isotonic salt solution prepared? 



(i) What is the meaning of the terms minimal and maximal re- 

 sistance of red blood-corpuscles? 



(j) Of what practical value is this test? 



