30 Bacterial Disease of the Mango 



Cylinders of potato on which the organism had been growing for 

 ten days or longer, when tested with iodine gave the purple red reaction 

 characteristic of amylodextrin, but did not reduce Fehling's solution. 



Invertin enzymes. Tube cultures in nutrient broth were prepared 

 and incubated as in the previous experiment. At the end of the 

 incubation period the cultures were mixed with an equal quantity of a 

 2 % solution of saccharose containing 2 % phenol and allowed to stand 

 for six hours. When tested at the end of this time, it was found that 

 the mixture did not reduce Fehling's solution, therefore there were no 

 invertin enzymes present. 



Rennet and lab enzymes. Tubes prepared and incubated as before 

 were heated at 55° C. for 30 minutes, in order to sterilise them without 

 destroying any enzymes which might be present. After this 5 cc. of 

 the culture was run into each of three tubes of sterile litmus milk. No 

 coagulation or change of any kind was observed in these during ten 

 days at 20° C. 



Acid 'production. There is no very marked change in the reaction 

 of any liquid medium in which this bacillus is grown. A series of 

 flasks containing nutrient broth with 2 % lactose, saccharose, glycerine, 

 laevulose and dextrose were inoculated and kept at a temperature of 

 30° C. for ten days ; at the end of that time the cultures were slightly 

 more acid than the controls, but only by 2 — 5 degrees of Fuller's scale. 



A test for organic acids was also made, using 500 cc. of 2 % dextrose 

 broth in which the organism had been growing for ten days. The only 

 reaction obtained was a rather doubtful one for succinic acid. 



Alcohol production. The first distillate of a ten days old culture in 

 2 % dextrose broth was divided into three portions. 



To the first was added LugoPs iodine solution, then a little NaOH 

 solution. There resulted a smell of iodoform indicating the presence 

 of alcohol, acetone or an aldehyde. A small quantity of SchifFs reagent 

 was pipetted into the second portion ; in the greater number of cultures 

 tested there was no reaction, but in one case a faint pink colour appeared, 

 and there was probably a trace of aldehyde in the culture. 



To 10 cc. of the third portion was added 10 cc. of H 2 S0 4 and 1 cc. 

 of a 4 % solution of potassium permanganate. On adding SchifFs 

 reagent, after five minutes a decided red colour was developed, indicating 

 the presence of alcohol. A decided reaction for alcohol was obtained 

 repeatedly in the distillate from cultures in 2 % dextrose broth. 



Ammonia. Two flasks of nutrient broth were prepared, each con- 

 taining 100 cc. One of these was inoculated, and both were put in the 



