330 METHODS OF IDENTIFICATION AND STUDY 



Pipette into tube No. 7 0.5 c.c. = 0.005 c - c - 



haemolytic serum 

 Pipette into tube No. 8 0.3 c.c. =0.003 c - c - 



haemolytic serum [ From 



Pipette into tube No. 9 0.2 c.c. =0.002 c.c. f tube 2. 



haemolytic serum 

 Pipette into tube No. 10 o.i c.c. =0.001 c.c. 



hsemolytic serum 



5. To each tube add i c.c. of erythrocyte solution. 



6. When necessary (that is to say in tubes 2, 4, 5, 6, 

 8, 9 and 10) add normal saline solution to the mixture 

 in the test-tubes till the column of fluid in each reaches 

 to the same level. 



7. Shake each tube in turn, so as to thoroughly mix 

 its contents. Plug the mouth of each tube with cotton 

 wool, and place entire set in the incubator at 37 C. 

 for one hour. 



8. Remove the tubes from the incubator and into 

 each tube pipette o.i c.c. complement (guinea-pig's 

 serum) and replace tubes in incubator at 3 7 C. for 

 further period of one hour. 



9. Remove the tubes from the incubator, and if com- 

 plete haemolysis has not taken place in every tube, 

 stand on one side, preferably in the ice chest, for an 

 hour. 



10. Then examine the tubes. 



Complete haemolysis is indicated by a clear red 

 solution, with no deposit of red cells at the 

 bottom of the test-tube. 



Absence of haemolysis is indicated by a clear or 

 turbid colourless fluid, with a deposit of red 

 cells at the bottom of the test-tubes. 



The smallest amount of haemolytic serum that has 

 caused complete haemolysis is known as the minimal 

 haemolytic dose (M. H. D.) and if haemolysis has 

 occurred in all the tubes down to No. 7 the m. h. d. 

 of this particular serum is .005 c.c. = 200 minimal 



