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Scientific Proceedings (75). 



cultures is advisable. So far, in most of the reactions, unheated 

 bacteria have been used. Inasmuch as the method of production, 

 under these circumstances, is fraught with a not inconsiderable 

 element of danger, we have recently begun to use bacteria heated 

 to 6o° for a half hour, and, in the one series so carried out, no 

 deteriorating effect of the heating was apparent. These problems 

 of detail, as well as many others, are being more thoroughly in- 

 vestigated. 



20 mgm. of the moist tubercle-bacillus mass are weighed out, 

 placed in a conical 15 c.c. centrifuge tube, and to it are added 90 

 mgm. of table salt. With a glass rod, filed to roughness at the end, 

 this paste is ground by hand for about one hour. Distilled water 

 is then added to isotonicity; that is, 10 c.c. to the quantities above 

 described. This is the antigen. Just before using, it is shaken up 

 and the heavier particles are allowed to settle in the course of a 

 few minutes. Except for the removal of these larger elements, 

 the suspension is used as a whole without centrifugation and 

 without filtration. 



The antigen so prepared has hardly ever been found anticomple- 

 mentary in quantities as large as 1 c.c. and has given fixation with 

 positive sera (the inactivated sera used in quantities of 0.1 c.c.) in 

 amounts as low as 0.02 c.c. The titrations, as well as the reactions, 

 have been done with one half the original Wassermann quantities, 

 using a sensitization of two units of amboceptor and two units of 

 complement. So far, we have used the anti-sheep rabbit hemolytic 

 system. As a routine, the 37 0 one-hour water-bath incubation 

 has been employed. A number of parallel series have been done 

 by the four-hour ice-box method, but, since this seems to make 

 little difference in the results, the time-saving 37 0 method was 

 decided upon as a routine procedure. The antigen appears to be 

 quite stable. We have used with satisfaction antigens as old as 

 six or seven weeks, kept on ice. 



We are ready to report the results of 602 cases tested. Of 

 these 103 were negative for tuberculosis; that is to say, they 

 represent patients in whom, clinically, tuberculosis was excluded. 

 226 cases were clinically diagnosed as actively tubercular. Their 

 sera tested gave the following results: 



"Stage one" cases: 32 in all with active clinical symptoms gave 



