408 F. M. Rolfs 



Toleration of sodium hydroxide. — Beef bouillon having a reaction of 

 + 10 Fuller's scale was used. Sufficient sodium hydroxide was added to 

 obtain a reaction of 0, — 2, — 4, and so on for every two degrees of Fuller's 

 scale to — '30. The sodium hydroxide was added just before the last 

 sterilization. Titrations made iixunediately following the sterihzation, 

 while the medium was still warm, showed an apparent loss of alkalinity. 

 In many cases, although not alwaj^s, the check lots of the medium titrated 

 on the fifth day or later gave the original reaction. 



Tubes inoculated and placed in an incubator at 25° C. gave a good 

 growth in all cultures down to — 10 in forty-eight hours. There was 

 a slight growth in the — 10 cultures, and at the end of two weeks a very 

 sHght growth occurred in the — 13 cultures. No growth occurred in 

 the tubes containing larger amounts of sodium. The best growth was 

 in cultures containing from — 2 to — 4 sodium hydroxide. 



Toleration of hydrochloric acid. — Ordinary beef bouillon having a reaction 

 of + 12 Fuller's scale was used. Sufficient hydrochloric acid was added 

 to 100 cubic centimeters of the bouillon to obtain a reaction of + 14, + 16, 

 and so on for every two degrees of Fuller's scale to + 36. There was a very 

 good growth in forty-eight hours in all the tubes up to + 22, and a sfight 

 growth in the lot having a reaction of + 24. A very sfight growth was 

 observed on the fourth day in the medirnn having a reaction of + 26 ; 

 this growth became slightly stronger by the tenth day. No growth 

 occurred m any medium containing larger quantities of acid. The best 

 growth developed in lots containing from + 12 to +20 acid. 



Resistance to drying. — Small drops of four-days-old bouillon culture 

 were placed on sterile cover glasses in a covered sterile petri dish, and left 

 in an incubator at room temperature of from 18° to 23° C. At intervals 

 of twenty-four hours one of the cover glasses was transferred to a tube of 

 sterile bouillon. Three tubes were used for each test. Growth occm'red 

 up to the eighth day, after which the tubes remained sterile. 



This experiment was repeated a number of times with bouillon cultures 

 from four to ten days old. As a rule there was no growth after the eighth 

 day; in one case, however, growth occurred on the fifteenth, and in another 

 case on the twenty-first, day. 



Effect of sunlight. — Hiss-glucose tubes inoculated from a three-days-old 

 bouillon culture were poured into petri dishes and placed in the bright 

 sunhght for forty-five and sixty minutes, respectively, half of each plate 



