THE WASSERMANN REACTION 629 



in cases of doubt the tubes may be centrifuged for two to three 

 minutes ; haemolysis of even slight degree leads to some staining 

 of the fluid above the deposited corpuscles. . 



A porcelain basin containing saline is kept at hand. From 

 it the saline for making up antigen solution, hsemolytic system 

 and complement dilutions and for the quill tubes is pipetted. 

 The throttled pipettes are also rinsed with it between each 

 different reagent pipetted and each specimen of serum, etc. ; 

 experience will soon indicate when rinsing is required. 



Two or three thicknesses of white filter-paper, 10 in. x 6 in., 

 should be placed in front of the worker. On this background the 

 measurement of the volumes with the throttled pipettes is much 

 facilitated and the traces of fluid left in the pipettes are absorbed 

 by placing their points upon it. 



Sheep's Corpuscles. The defibrinated sheep's blood will keep 

 for three to four days in the ice safe. If a trace of formalin be 

 added to the washed corpuscles, they will keep for five to six days 

 in the ice safe. 



After washing and centrifuging, 1 volume of the well-deposited 

 sheep's corpuscles are mixed with 3 volumes of saline, thus giving 

 a 25 per cent, suspension of corpuscles. 



In a mixture of citrate solution (3-8 per cent, sodium citrate in 

 distilled water), two parts ; dextrose solution (5-4 per cent, 

 dextrose in distilled water), five parts ; and deposited corpuscles, 

 three parts, the corpuscles will remain intact for three or four 

 weeks. 1 



Standardisation of Complement. Supposing no haemolysis 

 occurs in any of the complement dilutions in the saline series, this 

 may be due to a variety of causes, such as : 



1. Poor complement. While it is better then to use a fresh 

 sample of complement, the original complement may be used 

 provided a dilution of not less than 1 in 10 haemolyses. 



2. Too weak haemolytic serum. This may be tested by re- 

 standardising the hsemolytic serum. 



3. Too strong saline (1-2 per cent, saline will fix). 



4. The wrong corpuscles are being used, e.g. ox corpuscles 

 instead of sheep's corpuscles may have been obtained from the 

 slaughter-house (this has actually happened). 



1 Rous and Turner, Journ. Exper. Med., vol. xxiii, 1916, p. 219. 



