S. G. Paine and H. Stansfield 37 



Agar streak + 10. Incubated at 22° C. Streak from straight wire 

 inoculation 2 to 1 nun. wide after 24 hours, margin entire, surface raised 

 0-5 mm., "wet shining," dirty white with faint yellow tinge, distinctly 

 yellow when collected on a wire. 



Agar stab + 10. Incubated at 22° C. Growth along the stab uniform 

 to bottom with echinate margin, surface growth after 24 hours 3 mm. 

 diameter and raised 0-5 mm. 



Potato agar. Incubated at 22° C. Very strong growth after 24 hours. 

 Characters as on bouillon agar but perhaps a trifle more strongly yellow 

 tinted. 



Bouillofi + 10. Incubated at 22° C. Well clouded after 24 hours. 

 Slight ring but no pellicle. 



Thermal Death Point. Twelve tubes of bouillon were placed in a 

 water-bath and raised to 47° C. registered on a thermometer with its 

 bulb immersed "in water in a similar tube. The tubes were inoculated in 

 duplicate with a loopful of a bouillon culture of 24 hours growth. The 

 temperature of the bath was raised 2° C. between the inoculation of each 

 pair of tubes and the inoculated tubes were maintained at their appro- 

 priate temperatures for 10 minutes, then plunged into cold water. All 

 were incubated at 25° C. for 7 days. The thermal death point was found 

 to lie between 51° and 53° C. 



(iii) Physiological Characters. 



Bouillon {"Jardox'') + 2 j)er cent, sugar. Acid and gas formed in 

 presence of glucose, sucrose and mannite. The amount of gas was not 

 large and occupied only one-tenth of the volume of a Durham's tube 

 after 7 days incubation at 22° C, and was approximately the same in 

 each case. A slight ring formed, but no pelHcle. Bleaching of the Htmus 

 occurred at the bottom after 4 days. No acid nor gas formed in lactose 

 bouillon though growth was indicated by slight turbidity and ring 

 formation. 



Bouillon {"Jardox") + 1 per cent, nitrate. Nitrite was present after 

 24 hours at 22° C. and was still present after 2 months, at which time, by 

 transferring to other media, the organisms were shown to be still viable. 



Potato plug. Growth well visible after 24 hours at 22° C, and strongly 

 developed after 48 hours, faint yellow in colour; the surrounding medium 

 was not discoloured. The plug ground in a mortar after 12 days and 

 suspended in 300 c.c. of water gave, when tested with iodine, a more 

 purple colour than a control plug, showing slight diastatic action had 

 occurred. 



