200 



Journal of Agricultural Research voi. xviii, no. 4 



a correspondingly high increase of 0.88 per cent. Where 20 cc. of 

 inoculum were used it will be observed that the polarization was reduced 

 18.4 as compared with the control, or a decrease of 4.55 per cent sucrose, 

 and the reducing sugars were increased to 2.04 per cent. Again no ger- 

 mination or contamination could be detected in a microscopic examina- 

 tion. 



Since the particular problem which gave rise to the present investi- 

 gation — namely, the deterioration of sugar — is concerned primarily 

 with solutions of high concentration, it was planned to corroborate the 

 above evidence by repeating the experiment and using a sugar solution 

 of 20 per cent by weight, or double the concentration of that previously 

 employed. The methods and technic were identical with those described 

 in the experiment just reported, except that in this case there were 

 fewer spores present in the inoculum. 



Table IV. — Analyses oj 20 per cent sugar solutions inoculated with spores of Aspergillus 



niger 



[Twenty-four hours' incubation] 



In Table IV are recorded the results of the analyses after 24 hours' 

 incubation at 45° C. Only the averages of closely agreeing triplicate 

 determinations are here presented, and corrections for amount of inocu- 

 lum are calculated. It will be observed that the polarization and reducing 

 sugars of the flasks receiving 10 cc. of sterile distilled water heated to 

 63° and those heated to 100° were the same Ten cc. of spores heated 

 to 100° gave a slightly higher polarization, but these variations are 

 probably the results of the sterilization process, which did not affect all 

 flasks in an identical manner. However, there is no question concerning 

 the reduction in polarization as effected by 10 cc. of spores heated to 

 63°, which amounts to 3, or a decrease of 0.72 per cent sucrose. The 

 reducing sugars show a somewhat greater increase — 0.33 per cent. Where 

 20 cc. of spores were employed, the polarization was 52.9 as compared 

 with 61 in the control flasks, a reduction of 8.1 or a decrease of 1.94 

 per cent sucrose. Correspondingly there was an increase in reducing 

 sugars of 1.16 per cent. No germination or contamination could be 

 detected by a microscopic examination. Thus the results obtained 

 with a 20 per cent sugar solution confirmed those previously obtained 



