THE WASSERMANN REACTION 611 



together with sheep's corpuscles is used as the hsemolytic system 

 in some methods, e.g. Fleming's. In the ordinary methods, the 

 serum is too diluted for this hsemolytic effect to be exerted. 



(d) The Fluid to be Tested. This will be either the blood-serum 

 or the cerebro- spinal fluid of the patient. Either should be free 

 from corpuscles. If foreign complement is to be used, the serum 

 is inactivated by heating to 56 C. for half an hour. The cerebro - 

 spinal fluid is not inactivated. 



The Method. The Wassermann reaction to be accurate must 

 be carried out quantitatively, and the particular volumes of the 

 various constituents adopted must always be used. Thus 

 Fildes and Mclntosh employ the following volumes : 0-1 c.c. of 

 patient's serum to be tested, 0-5 c.c. of antigen dilution, 0-5 c.c. 

 of complement dilution, and 0-5 c.c. of hsemolytic system. In 

 different methods the total number of volumes of all the consti- 

 tuents varies from ten to fifteen, the volume of the patient's serum 

 being taken as one. This variation has no influence on the 

 accuracy of the results obtained, but it may entail some slight 

 adjustments of the strengths, and some variation in the volumes, 

 of the reagents employed. This, however, is determined by the 

 standardisation of the reagents, which is always carried out in 

 any method by the same technique as employed in the test 

 itself. Although particular volumes of the consituents must be 

 adhered to, these need not be definite quantities (i.e. c.c.'s or 

 fractions of a c.c.), so long as the same ratio of volumes is main- 

 tained. Thus, in the Fildes and Mclntosh technique, the volume 

 V may be any quantity (but not necessarily a known quantity) 

 so long as the ratio of constituents 1 V serum + 5 V antigen 

 + 5 V complement + 5 V system is adhered to. 



The technique for carrying out the test may therefore con- 

 veniently be divided into the "large volume " method, in which no 

 volume will be less than 0-1 c.c., and the " small volume " method 

 in which the unit volume used in the test will be under 0-05 c.c. 

 The writer is unable to discern that the "large volume" method can 

 claim any advantage over the "small volume" one, while the 

 " small volume " method possesses advantages, (1) a sufficiency of 

 the patient's blood maybe obtained from a prick and there is no need 

 to puncture a vein, (2) it is more economical of the reagents antigen, 

 hsemolytic serum, and complement and it is rarely necessary to kill 

 a guinea-pig, (3) the time of incubation of the mixtures is lessened. 



392 



