BY R. GBEIG-SMITH. 



79 



growths became depressed progressively, making it clear that an acid condition 

 of the medium is unsuitable. In dextrose and saccharose litmus broths, the media 

 became reddened and then bleached but the growth was feeble. Meat extract 

 is not a suitable source of nitrogen. Urea and ammonium salts are quite unsuit- 

 able while on the other hand peptone and asparagin are good. 



In peptone water with nitrate, the nitrate is reduced to nitrite. 



In the primary isolation of the high temperature organism, gi-owths were 

 obtained from stack-bark which had been wetted with water and with N/100 

 sodium hydrate and, of the two, the soda contained the greater number of bacteria 

 per loop of suspension. In following up this observation, stack-bark was put 

 into bottles and wetted with dilute sodium hydrate of varying strengths. The 

 liquids rose half way to the surface of the bark. The bottles were closed with 

 corks fitted with glass tubes drawn out at one end to a capillary point in order to 

 lessen the evaporation of the liquid contents. They were incubated at 70° and 

 from these growths were obtained, but as no gas was produced in saccharose agar, 

 it was considered that 70° was too high for laboratory work. Accordingly new 

 portions of stack-bark were taken, wetted with sodium carbonate and incubated at 

 60° . The growth and gas-formation produced by stroking loops of the alkaline 

 liquors on saccharose agar are noted in the table. 



S=slight. 



Another experiment with stronger dilutions of sodium carljonate was made 

 and the following results were obtained. 



S = slight. 



A bulk culture in N/5 sodium carbonate gave a gas-forming growth in two 

 days, but not in one day. 



The experiments show that N/5 or N/10 sodium carbonate is best for de- 

 veloping the organism that produces gas in saecharose-agar . The organism is 

 contained in the condensed water of the slopes which show gas formation and 

 when this water was seeded into litmus broth containing either saccharose or 



