72 Huctevhd BUijht of Pear BlihsaoiHH in South Africa 



A quantitative test for acid production was carried out with some 

 of the sugars mentioned above. Cultivations were pi'epared in bulk 

 in fhisks containing 50 c.c. nutrient broth and 2 % of the substances 

 to be tested. They were incubated for 10 days at 20° C. and were as 

 follows (expressed in degrees of Fuller's scale). 



Sugar Culture Control 



Dextrose +35-5 +15-6 



Glycerine + 10 + 15 



Lactose +15 



Laevulose +10 +15 



Saccharose +15 



It will be observed that except in the case of dextrose the culture 

 was slightly less acid than the control. 



No reaction for alcohol or aldehyde was obtained in the distillate 

 from a cidture in dextrose bouillon. 



Indol. There was no indol in cultures in Dunham's solution or 

 in nutrient bouillon after 10 — 12 days at 20° C. Tests for phenol 

 were also negative. 



Pigment 'production. It has already been pointed out in the section 

 on the cultural characters of the organism that it produces on certain 

 media a distinct greenish or greenish yellow fluorescence. 



Colour destruction. Methylene blue was almost completely reduced 

 in 24 hours; neutral red and rosolic acid were not reduced. Litmus 

 was partially reduced in milk cultures but not in nutrient broth. 



Nitrate reduction. Nitrates were not reduced to nitrites during 

 ten days growth in nitrate broth and in nitrate peptone water at 25° C. 



Gas production. It has been stated that no gas is produced in 

 fermentation tubes containing various sugar solutions. 



Cultivations were prepared in iron and lead peptone solution ; the 

 precipitate began to blacken after some days, that in the tubes to which 

 iron tartrate had been added becoming decidedly black, thus showing 

 that some sulphuretted hydrogen had been liberated. 



Growth under anaerobic conditions. The organism grows very slowly 

 in glucose formate agar in Bulloch's apparatus from which the oxygen 

 has been absorbed. Control tubes under ordinary atmospheric con- 

 ditions made a very vigorous growth. 



Temperature. The optimum temperature for growth lies between 

 25 and 30° C. The organism grows much more slowly at 20 than at 

 25° C. and at 35 than at 30° C. 



The thermal death point is 49° C, ten minutes exposure in thin 

 walled test tubes containing 10 c.c. nutrient broth. 



