Studies in Complement Fixation. 



171 



negative for complement fixing antibodies, although a reasonable 

 number of such antibodies might still be present in the serum. 

 With this possibility in mind, a series of complement fixation tests 

 were carried out, using complement gradations of ij units, ij 

 units, if units and 2 units. The quantity of serum employed 

 was 0.01 c.c. 



It was observed that the same serum which gave negative 

 results when 2 units of complement were employed, gave weak 

 positive results with if units of complement; stronger positive 

 results with i| units; and still stronger with if units of comple- 

 ment. In the last case the serum showed slight anticomple- 

 mentary properties, which disappeared after about 10 minutes' 

 incubation in the water bath. 



This work is still being continued, but the results obtained 

 thus far indicate that the employment of 2 units of complement 

 in complement fixation tests is too great an excess of this ingredient 

 for correct results in some cases, and that the employment of 

 lesser quantities of complement, properly controlled, would serve 

 as a finer measure of the complement fixing power of a given serum. 



83 (1665) 



The thermostability of complement fixing antibodies resulting 

 from protein immunization. 



By R. L. KAHN. 



[From the Bureau of Laboratories, Michigan Department of Health, 

 Lansing, Michigan.] 



In a series of studies on the rate of destruction of antisyphilitic 

 complement fixing substances by heat, recently reported by Kahn 

 and Boyd, 1 it was observed that in practically all cases these 

 substances were destroyed when subjected to temperatures ranging 

 from 60 to 65 degrees C. These results were obtained by heating 

 a number of fractions of syphilitic sera at different temperatures 

 in the water bath and running regular Wassermann tests with each 

 fraction. It was felt, however, that the results obtained with 



1 Kahn and Boyd, Proceedings Society of Amer. Bacter., Dec, 1920. Abstr. of 

 Bact., forthcoming Issue. 



