DEVIATION OF COMPLEMENT 137 



the others. The method of testing the deviation of comple- 

 ment is carried out in two stages. (1) To each of a series of 

 test-tubes a given amount of the anti-serum, usually 0-05 c.c., 

 is added along with a given amount of the homologous 

 serum, and the volume is made up with 0-8 per cent 

 solution of sodium chloride to 1 c.c. To the several tubes 

 varying amounts of complement (normal serum of rabbit or 

 guinea-pig) are added, the smallest amount being about the 

 minimum hsemolytic dose for the amount of red corpuscles 

 to be afterwards used in the test. It will be seen that in 

 this stage there is always a mixture of three substances, the 

 serum, the anti-serum, and the complement whose absorp- 

 tion is to be observed. The tubes are placed in the incubator 

 at 37 C. for one and a half to two hours to allow time for 

 combination. (2) At the end of that time 1 c.c. of a 5 per 

 cent, suspension of red corpuscles treated with the corre- 

 sponding immune-body is added to each tube and the tubes 

 are again placed in the incubator for one and a half hours. 

 We can thus observe the tube in which there is the first trace 

 of lysis, and the tube in which lysis is first complete. It is 

 convenient to prepare several series of tubes with different 

 amounts of the homologous serum, 0-01, 0-001, 0-000,1 c.c., 

 '&c., in each series. In each experiment a control series with 

 anti-serum along with different amounts of complement alone 

 is prepared, and the difference between the lysis in this and 

 the other series is interpreted as being due to the presence 

 of the homologous serum. We also have in each series a 

 tube containing corresponding amounts of serum and anti- 

 serum alone, to show precipitation. It is evident that the 

 conditions of experiment may be varied by making the 

 amount of the homologous serum (precipitinogen) fixed, 

 and varying the amount of anti-serum. 



It is thus seen that we have in such experiments two 

 substances and their anti-substances, viz. serum + anti-serum 

 and red corpuscles + immune-body : opportunity is given to 



