PHYSICO-CHEMICAL PROPERTIES 83 



Capsular material of B. pestis: 



Cultures were grown on agar pH 6.6 at 37° c. for 36 hours. 

 The 'washings were made in physiological NaCl solution, slightly 

 alkalized with NaOH and shaken for one to two hours. The 

 material was then heated at 56° c, and centrifuged. The authors 

 contended that the supernatant fluid collected contained the cap- 

 sular material. The assimiption ^vas based on the fact that the 

 sediment consisted of approximately the same number of bacteria 

 as the original suspension; that the shaken bacteria were deprived 

 of capsule; that the supernatant fluid precipitated with wiiole 

 B. pestis immune serum; and finally, becatise the addition of 

 ^\'eak acetic acid gave no precipitate, thus excluding the presence 

 of the nucleoprotein. 



Both fractions were tested for skin-preparatory and reacting 

 potencies in rabbits and in spite of the fact that large amounts 

 were employed, they pro\ed totally inactive. 



CHEMICAL STUDIES ON ACTIVE PRINCIPLES OF B. DVSENTERIAE 



Olitski and Leibowitz (1935) prepared a suspension of growth 

 of B. dyseuteviae Sliiga on agar and obtained P], P- and C-fractions 

 of Fiirth and Landsteiner (1928) and also fractions Q and T and 

 the Haptene according to the method of White (1932, 1933) . In 

 addition, after removing Q and T fractions, bacteria were boiled 

 for two hoius in NaCl solution, both with and without addition 

 of 10 per cent glycerol. The material was then fikered to remove 

 the bacteria and the filtrate precipitated by addition of two vol- 

 umes of alcohol. The fractions were called gi (glycerol) and Sa 

 (saline) . All the materials were dried and resuspended in saline 

 to have 1 mgm. of dry weight per 1 c.c. of saline. Pi fraction con- 

 tained 2.3 of nitrogen; -within 1 hour it hydrolyzed incompletely 

 with 4 per cent HC'l and completely with 10 per cent HCl. It was 

 j^ositive for P^O.-, and reduced Fehling soluti(jn; Pi fraction con- 

 tained 7.3 of nitrogen; it was completely hydrolyzed by 6 per cent 

 HCl within one hour; it was slightly positive for P-C).-, and failed 

 to redtice Fehling solution. Apparently then, these fractions rep- 

 resented a mixture of protein and carbohydrate Avhich could be, 

 however, further purified. 



These authors tested the various fractions for their ability to 

 induce the state of reactivity and judged their potency by the 

 size of the lesions obtained; 0.3 c.c. was used for preparation and 



