20 
North Carolina Agricultural Experiment Station 
(9) Wyeth, F. J. S. The effects of acids oil the growth of Bacillus coli. 
Biochem. Jour. 12: 382-401, 1918. 
(10) Foster, Laurence, F. The relation of hydrogen ion concentration to the 
growth, viability and fermentative activity of Streptococcus liemolyti- 
cus. Jour. Bact. 6: No. 2/161-209, 1921. F. A. W. 
SUMMARY 
Cultural studies have been made on the tolerance to acids of various plant 
pathogenic bacteria, including the cabbage black rot organism, one commonly 
causing decay of root crops, two causing leaf spots of soybean and two caus¬ 
ing tobacco leaf spots. 
Different acids of the same H-ion concentration are not able to exert the 
same influence in inhibiting cell multiplication. Acetic is more toxic than any 
other of the acids employed, an observation which accords with that of others. 
A greater pH concentration in agar than in bouillon is required to inhibit 
growth, this difference ranging between 0.2 and 0.4 pH with the same organ¬ 
ism and the same acid. 
LITERATURE CITED 
(1) Cohen, Barnett, and Clark, Wm. Mansfield. The growth of certain bac¬ 
teria in media of different hydrogen ion concentrations. Jour. Bact. 
4 :409-427, 4 fig. 1919. References, p. 426-427. 
(2) Norton. John F., and Hsu, Paul H. The physical chemistry of disin¬ 
fection, 1. Jour. Infect, Diseases 18: 180-194, 1916. Bibliographical 
footnotes. 
(3) Svanberg, Olaf. Uber einige Milclisaurebakteriologische pli Bestirn- 
mungen (The Determination of a Few Lactic Acid Bacteriological pH 
Values) 81 p. Stockholm, 1918. Inaug. Diss. Abst. in Absts. Bact. 
4: 284-285, 1920. 
(4) Winslow, C-E., A., and Lochridge, E. E. The toxic effect of certain 
acids upon typhoid and colon bacilli in relation to the degree of their 
dissociation. Jour. Infect. Diseases 4: 547-571. 1906. References p. 
570-571. 
(5) Wolf, Frederick A., and Sliunk, I. V. Solid culture media with a wide 
range of hydrogen or hydroxyl ion concentration. Jour. Bact. 6: 
325-330. 1921. 
