PHYSICO-CHEMICAL PROPERTIES 67 



\vasliings"' and disintegrates were used for intravenous injections, 

 twenty-foiu- horns later. Each dihition ^vas tested in a group of 

 three rabbits. The restdts are recorded in Table n. 



As is evident from Table n, acctuate determinations of the 

 potencies of various preparations can be made only by titrations 

 to the end-point, but not by comparing the percentage of positive 

 results obtained with given dilutions in small groups of rabbits. 

 Thus, if one should compare, for instance, meningococcus wash- 

 ings 1 and 2 in diltuion 1:100 by the percentage of positive 

 rabbits, both preparations ^vould appear of the same strength. 

 Titrations to the end-point show that one preparation is ten 

 times stronger than the other. This is due to natural resistance 

 sho^vn by a certain percentage of rabbits to moderate doses of 

 active principles, which, ho^vever. is not displayed with large 

 doses. 



As is also seen from Table 11, the concentration of toxic fac- 

 tors in the first ^vashing- of a oriven number of meningococcus cells 

 was approximately 1000 times stronger than in the disintegrate 

 of the same number of cells dissohed in the same volume of 

 NaCl solution. With B. typhosus, the first washing ^vas about 30 

 times stronger than the distintegrate prepared according to Bes- 

 redka's method. Evidently, then, the major portion of the factors 

 was obtained in the first washing and only an insignificant 

 amoiuit Avas found in disintegrates and the further washings. 

 The process of washing probably caused \'ery little disintegration 

 since in those experiments young bacterial cells on solid media 

 were centrifuged as soon as they were suspended in NaCl solu- 

 tion and the supernatant fluid ^vas separated from the sediment 

 shortly after completion of centrifugal ization. It can be con- 

 cluded, therefore, that the toxic substances necessary for the phe- 

 nomenon are extracellular (Shwartzman, 19320) . 



(iratia and Linz (1932c) carried out a series of experiments 

 witii bacterial cultures dissolved with bacteriophage and strepto- 

 thrix. Staphylococcus ^vas inoctdated into the broth four hoins 

 later. When the broth became turbid, 5 drops of anti-staphylg- 

 coccus bacteriophage ^vere added to several of these tubes. The 

 follo^ving day the bacteriophage-containing tubes were filtered 

 and the filtrates tested in rabbits. Neither of the filtrates showed 

 any activity. B. coil cultures were similarly treated. The filtrates 

 of normal B. coll cultures and those dissolved ^vith bacteriophage 

 yielded the active principles. It appears, therefore, from the ob- 



