618 A MANUAL OF BACTERIOLOGY 



Method : fill in the 8 tubes in the rack as indicated : 



Front Row (A) for Estimating m.h.d. of Complement. 



1234 



1. Saline .... 0-85 0-8 0-75 0-7 



2. Complement (tube b) . .0-15 0-2 0-25 0-3 



3. Corpuscles -f amboceptor 



(tube d) . . . .0-5 0-5 0-5 0-5 



Back Row (B) for Antigen Control. 



1. Saline .... 0-35 0-3 0-25 0-2 



2. Complement (tube c) . . 0-15 0-2 0-25 0-3 



3. Antigen (tube e) . . 0-5 0-5 0-5 0-5 



Shake. Put rack into a water-bath at 37 C. for ten minutes to 

 see whether the front row tubes are laking properly, and then 

 transfer to the incubator to complete one hour. Eead the m.h.d. 

 of complement in the front row and put 0-5 c.c. of corpuscles 

 (tube d) into each of the back row tubes. Put into the water-bath 

 and note whether the tube behind the m.h.d. tube is laked (about 

 fifteen minutes or less). If so, continue as in following table : 



If m.h.d. is tube 1 use 0-5 c.c. of a 1 in 33 dilution of complement for each 



tube. 



2 1 in 24 



,,3 ,,1 in 19 



4 1 in 16 



If the antigen tube behind the m.h.d. tube is not completely 

 laked and the next one to the right is, the latter will indicate the 

 complement dilution to be used, but if this also is not clear the 

 complement is unsatisfactory and that of another guinea-pig 

 must be taken. 



[The author has found the Fildes and Mclntosh antigen to be 

 very satisfactory. It seems always to work at the strength 

 named, retains the same potency for long periods and does not 

 require standardising. The two bottles should be kept in a dark 

 cupboard, not in the ice chest. 



The object of the antigen control is to eliminate an anti-com- 

 plementary guinea-pig serum. Occasionally, a guinea-pig serum is 

 absorbed with great avidity by the antigen ; it is then termed 

 " anti-complementary " and is unsatisfactory. 



