58 Bacterldl Bliijht of Pear Blosaoius in Soxf/i Africa 



about 2 mm. high, the surface being almost semi-cylindrical ; on one 

 cylinder the edges only were raised and the centre depressed. 



Beet. On beet the organism grows fairly well, producing a raised, 

 gelatinous-looking growth along the needle track ; the growth on the 

 surface of the liquid takes up the colour from the medium to some 

 extent and becomes fairly pink. 



Blood serum. The organism does not Ii([ueiy blood serum, and the 

 streak is similar to that on nutrient agar, but the growth less copious. 



Nutrient bouillon becomes slightly clouded in 2f hours, and in two to 

 three days is fairly heavily clouded. There is a considerable amount of 

 sediment and a very thin }jellicle. In very old cultures a slight fluores- 

 cence may sometimes be observed. 



Milk is not curdled, but is very slowly peptonised. In nine days 

 two-thirds to foui'-tifths of the liquid is clear ; after one month the milk 

 is completely peptonised, the colour is reduced in litmus milk, and the 

 medium is distinctly alkaline to litmus. 



Dunham's solution is slightly cloutled. 



Uschinsh/s solution. No growth. 



Cohfis solution. No grow^th. 



Nutrient bouillon over chloroform. Growth was unrestrained in the 

 presence of chloroform. 



Eyg albumen. A medium composed of 1 gram powdered egg albu- 

 men and 50 c.c. of -05 % potassium phosphate was well clouded in five 

 days. 



Physical and Biochemical Relations. 



Proteolytic activity. The organism is a fairly active proteolytic 

 agent ; it slowly peptonises milk and there is a distinct smell of ammonia 

 from liquefied gelatine. 



Cultures in nutrient bouillon were tested for ammonia by distillation 

 after five to 10 days at 20*^ C. In each case 50 c.c. of medium were 

 found to contain approximately -02 gramme of ammonia nitrogen. 



In the egg albumen medium described above there was a positive 

 reaction for peptone after five days. A quantitative test by Sorensen's 

 method showed that 50 c.c. of the medium after five days contained 

 •0035 nitrogen, in the form of amino acids and ammonia, i.e. approxi- 

 mately 2-3 % of the total nitrogen had been broken down. A distil- 

 lation test for ammonia showed that the whole of this was in tJie form 

 of ammonia; and cultures tested after 10 days gave an almost identical 

 reading; the amount of ammonia had not increased. 



