Apr. 12,1924 Development of American Foulbrood 165 



7. The food of the older honeybee larva contains a high percentage of reducing 

 sugar, which is derived from the honey or nectar used in its production. The 

 concentration of reducing sugar in the larval intestine is more than sufficient 

 to inhibit the growth of Bacillus larvae until after feeding has ceased. After feed- 

 ing ceases, the remaining reducing sugar is rapidly assimilated, so that by the 

 seventh day the concentration of sugar has been reduced sufficiently for the 

 active growth of Bacillus larvae to occur. 



8. The incubation period of Bacillus larvae is 24 to 48 hours, so that growth 

 sufficient to kill the larva does not occur until it has completed the spinning of 

 its cocoon and has extended quiescent in the cell, on or after the eighth day, by 

 which time all reducing sugar has disappeared from the larva. 



9. The delayed death of the larva in American foulbrood is, therefore, corre- 

 lated with the inhibiting effect of unassimilated reducing sugar in the intestine 

 upon the germination and growth of Bacillus larvae. 



10. Bacillus larvae has the ability to produce considerable acid, but the hydro- 

 gen-ion concentration of the decomposing material is not thereby increased, 

 because of the neutralizing effect of protein decomposition products. The 

 hydrogen-ion concentration of the diseased larva throughout its decay varies 

 only slightly from Ph = 6.8. * 



11. Bacillus larvae not only utiUzes reducing sugar for its initial growth, but 

 also completely hydrolyzes the glycogen of the larval body tissues in the 

 process of decomposition. 



12. Bacillus larvae has the ability to decompose nitrogenous materials, with 

 the formation of amino-acids, indol, and ammonia, but the hydrogen-ion con- 

 centration is not decreased by this action, because of the concomitant pro- 

 duction of acids from carbohydrates. 



13. Bacillus larvae apparently has no action on fat. 



14. The biochemical data herein presented for the first time explain the 

 remarkable characteristics of American foulbrood, which were left entirely 

 unexplained from observations on etiology alone. 



LITERATURE CITED 



(1) Allen, P. W. 



1918. A SIMPLE METHOD FOR THE CLASSIFICATION OF BACTERIA AS TO 



DIASTASE PRODUCTION. Jour. Bact. 3: 15-17, illus. 



(2) Ayers, S. H., and Rupp, P. 



1919. EXTRACTS OF PURE DRY YEAST FOR CULTURE MEDIA. Jour. BaCt. 5: 



89-98. 



(3) MuDGB, C. S., and Rupp, P. 



1920. THE USE OF WASHED AGAR IN CULTURE MEDIA. Jour. BaCt. 5: 



589-596. 



(4) Baker, H. R. 



1922. substitution of brom-thymol-blue for litmus in routine 

 LABORATORY WORK. Jour. Bact. 7: 301-305. 



(5) Benedict, S. R. 



1911. A METHOD FOR THE ESTIMATION OF REDUCING SUGARS. JoUr. Biol. 



Chem. 9: 57-59. 



(6) Bbrman, N., and Rbttgbr, L. F. 



1918. THE INFLUENCE OF CARBOHYDRATE ON THE NITROGEN METABOLISM 



OF BACTERIA. Jour. Bact. 3: 389-402. 



(7) Bishop, G. H. 



1922. cell metabolism in the insect fat-body. i. cytologicai 

 changes accompanying growth and histolysis of the pat- 

 BODT OF APIS MELLiFicA. Jour. Morph. 36: 567-601. 



