Ethel M. DoiDaE 59 



Milk cultures tested in the same way gave a strong reaction for 

 peptone and for tyrosin after 10 days; and there was -Oil — -017 grains 

 ammonia nitrogen in 50 c.c. of the medium. 



Aiiiylolytic action. Starch is very slowly destroyed; nutrient 

 bouillon containing -01 gram of soluble starch gave the red-brown 

 reaction of amylodextrin with LugoFs iodine solution after about 10 

 days, and in three weeks the starch had completely disappeared. 



Fermentation reaction. No acid or gas was produced in fermentation 

 tubes containing peptone water, tinted with litmus, and containing 

 2 % of any one of the following substances : — starch, laevulose, mannite, 

 glycerine, galactose, saccharose, dextrose, lactose. 



Indol. No reaction for indol was obtained at room temperature 

 in 10 days old cultures in peptone water and nutrient broth, but after 

 warming a slight, but quite definite coloration appeared after the 

 addition of sulphuric acid and a nitrite. 



Nitrates are not reduced to nitrites. 



Gas production. It has been mentioned that no gas is produced 

 in fermentation tubes containing sugar solutions. In iron and lead 

 peptone solution and bouillon the precipitate was decidedly blackened, 

 showing that sulphuretted hydrogen had been liberated. 



Atmospheric conditions. The organism is a facultative anaerobe ; 

 it grows slowly on glucose formate agar in an atmosphere devoid of 

 nitrogen. 



TeiHperature. The optimum temperature lies between 15 and 20° C. ; 

 the thermal death point has not yet been determined. 



III. The South African Disease. 



It has already been pointed out that so far as is known at present 

 the pear blossom blight only occurs in the Stellenbosch District and at 

 Elsenberg, that is to say in the region where the winter and early spring 

 is the rainy season and in that part of it where pears are extensively 

 grown. Several cases of blackening in blossoms and pearlets grown 

 in other parts of the country have been brought to our notice, but as 

 these occurred in hot dry weather after some six or seven months' 

 drought, it is more probable that the failure of the blossoms was due 

 in these cases to drought than to the bacterial blight, which only 

 spreads rapidly when the atmosphere is moist. Further investigation, 

 however, will be necessary before any definite statement as to the 

 geographical distribution of the disease can be made. 



