THE WASSERMANN REACTION 619 



Having standardised the complement, before proceeding with 

 the test the author does a control with a known negative, and a 

 known positive, serum (these sera may be kept on ice from the 

 previous batch of tests). 



The dilution of complement to be used in the test gives 2-| m.h.d. 

 of complement as found by the standardisation. Thus if tube 2 of 

 the front row (A) be the one giving complete haemolysis, this con- 

 tains 0-2 c.c. of 1-24 complement, and 2| times this dose in 

 0-5 c.c. (as used in the test) is obviously 0-5 c.c. of a 1 in 24 dilution, 

 and so with the other dilutions. An active complement gives 

 much sharper readings than a weak complement, even though 

 the proper dose of the latter be used, hence if tube 4 does not 

 hsemolyse completely, it is better to use the serum of another 

 guinea-pig, though the author has used the complement when a 

 dilution as low as 1 in 10 is required for the standardisation, but 

 it is not nearly so satisfactory.] 



V. PREPARATION OF SERUM FOR TESTING. While the comple- 

 ment is undergoing standardisation, or at any other time on the 

 day of the test, the sera should be distributed into the tubes. The 

 numbered capsules are centrifuged and a series of test-tubes 

 are set out in pairs in the racks, each pair numbered to corre- 

 spond to the capsules, i.e. two tubes for each serum, so that every 

 serum may be tested both with antigen and with saline. The 

 numbering of the tubes must be indelible, and is best carried out 

 by Donald's method. (1) Warm the tube in the flame. (2) Inscribe 

 a bold figure on it with ordinary blue-black ink. (3) Burn in the 

 ink by heating in the flame to a point short of the fusing tem- 

 perature. From each capsule transfer 0-1 c.c. of clear serum into 

 each of the pair of corresponding tubes. This is conveniently 

 done with Donald's dropping pipettes, thus : (1) Make a pipette 

 from glass tubing. (2) Pass the pipette through a particular hole 

 in a wire gauge plate, when it engages cut it off flush with the 

 plate. The actual hole to be used is found once and for all by 

 experiment. A pipette made in No. 53 Stubbs will deliver 0-1 c.c. 

 of serum in 4 drops. Always hold the pipette vertically and wash 

 with water between each serum. When the sera are all filled in 

 make the tubes into a bundle in some safe and convenient manner, 

 or pla.ce them in a rack, and suspend them in the inactivating 

 water-bath at 55-56 C. for thirty minutes. Then replace them 

 in the racks in sequence. 



