622 A MANUAL OF BACTERIOLOGY 



determine its degree of positiveness. This may be done in two 

 ways : (a) by testing in the same manner as in the test proper 

 two dilutions of the serum, viz. 1 in 2 and 1 in 4 ; (b) A better 

 method is to test the serum undiluted with increased amounts of 

 complement, viz. with 5 and with 7 minimal hsemolytic doses of 

 complement. These tests are done in exactly the same manner 

 as in the test proper. A serum giving complete fixation with 

 2| m.h.d. complement may be designated +, with 5 m.h.d. com- 

 plement + + , and with 7 m.h.d. complement + + + . If fixation 

 is partial, this may be designated if nearly complete, or ^ if a 

 good deal of haemolysis. The dilutions of complement to be used 

 in the " positiveness " determinations are : 



If this procedure be adopted, it will be necessary to pipette off 

 at least 0-6 c.c. of serum from each specimen of blood to be 

 tested, to inactivate this and to fill the tubes as required ; 0-1 c.c. 

 for each tube.] 



B'. THE WASSEBMANN REACTION. 

 SMALL VOLUME TECHNIQUE 



The following is an account of the Tildes and Mclntosh Wasser- 

 mann method adapted by the author to a " small volume " 

 technique. The unit volume employed is 20 cub. mm., i.e. 

 0-02 c.c. This is a very convenient volume and is the volume of 

 the hsemoglobinometer pipette, so that it can always be repro- 

 duced. Throttled pipettes are used for the measurement of the 

 volumes used in standardisations and in the test proper. 



Ordinary pipettes are used for the preparation of the reagents : 

 a 0-1 c.c. in tenths and hundredths for measurement of the 

 hsemolytic serum, 1 1 c.c. pipettes in tenths for measurements of 

 antigen and complement, and 5 c.c. and 10 c.c. pipettes in tenths 

 of a cubic centimetre for making up, and measuring out, the 



1 This can be obtained from Messrs. Hawksley, 357, Oxford Street, W. 



