E. M. Doidge :37 



take place when the tubes were removed from the apparatus and placed 

 in the incubator, the organism having been killed by prolonged exposure 

 to the gas. 



The ability of the bacillus to withstand short exposures of S0 2 

 was also tested. Transfers were made from a young culture to ten 

 tubes of slant agar, a generous quantity of the culture being used. 

 Two were placed in the incubator as controls, and the remainder were 

 exposed to a stream of S0 2 for periods varying from 15 seconds to 

 five minutes. In tubes exposed for 15 or 30 minutes there was a 

 slight growth along the needle track after five days ; in those exposed 

 for longer periods the organism was killed. Growth was abundant in 

 the controls. 



A drop of a liquid culture was introduced into each of eight tubes 

 of nutrient broth, and a stream of S0 2 passed through the tubes for 

 periods varying from 15 to 60 seconds. There was no clouding in any 

 of these. 



Reduced pressure. A set of tube cultures was prepared and sealed 

 in Bulloch's apparatus ; then the air was exhausted as completely as 

 possible from the bell jar. In this experiment the oxygen was not 

 absorbed. 



At the end of four days there was only a slight growth in the glucose 

 formate agar and in the formate broth tubes, but quite a good growth 

 in the tubes containing ordinary nutrient agar and broth. 



Effect of germicides. In connection with the spraying experiments 

 a series of cultures was made to determine the susceptibility of the 

 organism to various germicides. 



In testing substances which could be added to nutrient broth 

 without causing precipitates the procedure was as follows: A young 

 broth culture was used, one which had been kept at 30° C. for 

 24 hours. From this -1 cc. of the culture was dropped into each of a 

 number of tubes of + 15 broth, and this amount did not cause any 

 clouding of the medium. Into the tubes thus inoculated, each of which 

 contained exactly 10 cc. of broth, varying quantities of a solution of 

 the germicides were pipetted, about five tubes being used for each 

 percentage. 



After remaining in the incubator at 30° C. for 30 minutes a series 

 of plates was poured from one tube in each group, the remaining four 

 being returned to the incubator. The plates and tubes were kept 

 under observation for a number of days until it was certain whether 

 growth would take place or not. 



