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 throughdut its decay varies 
only slightly from P H =6.8. 
11. Bacillus larvae not only utilizes 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 nitrogeneous 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) - Mudge, 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) Berman, N., and Rettger, 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. cytological 
changes accompanying growth and histolysis of the fat- 
body of apis mellifica. Jour. Morph. 36: 567-601. 
