E. M. Doidge :n 



incubator at 30° C. After ten days, 2 grams of calcined magnesia were 

 added to each flask, and 50 cc. distilled from each. Neither of the 

 distillates gave any reaction for ammonia with Nessler's solution. 

 Ammonia is sometimes produced in media containing a nitrate, but 

 this point will be discussed under the heading "nitrate reduction." 



Indol and phenol. Tubes of peptone water in which the organism 

 had been growing for ten days at 30° C. always gave a distinct reaction 

 for indol with sulphuric acid and potassium nitrate, there was no such 

 reaction in the controls. 



A culture in a flask containing 300 cc. of nutrient broth was used to 

 determine the presence or absence of phenol. After ten days at 30° C. 

 the contents of the flask were tested for indol and phenol as follows. 

 After adding 50 cc. of HC1, the flask was connected with a condenser 

 and 50 cc. distilled over. The distillate was rendered strongly alkaline 

 with KOH and redistilled. The distillate tested with sulphuric acid 

 and potassium nitrite gave a decided reaction for indol. 



The residue, when cold, was saturated with C0 2 and redistilled. 

 This third distillate gave no reaction for phenol with Millon's reagent 

 or with ferric chloride. A control flask, similarly tested, gave no reaction 

 either for indol or for phenol. 



Pigment production. It has been stated in connection with the 

 description of the cultural characters of the organism that it is capable 

 of producing a yellow pigment on a variety of media ; and that this 

 pigment develops more rapidly at 30° — 37° C. than at lower tem- 

 peratures. The colouring matter is insoluble in water, hot or cold, in 

 alcohol, ether, chloroform or dilute acids. 



Colour reduction. The organism was grown in nutrient broth tinted 

 with various coloured substances; a number of trials were made in 

 each, but a typical set of tubes is selected in each case for detailed 

 description. In all the experiments the colour of the control tubes 

 remained unchanged. 



Litmus. The reduction of litmus in milk cultures has already been 

 described. The colour is also reduced in nutrient broth with or without 

 the addition of dextrose. In a vigorous culture reduction is complete 

 in 48 hours at 30° C, but with a less vigorous strain of the bacillus the 

 process was much slower and took as long as six days. 



In one instance the tubes before inoculation were bishop's purple 

 (XXXVII), in 24 hours the reaction of the tubes was more acid, and the 

 colour scarlet red (I). The following day reduction had commenced, 

 working from the bottom of the tube ; the lower half of the broth was 



