Studies on American Foul Brood of Bees: The Relative Pathogenicity of Vegetative Cells and Endospores Ofbacillus Larvaefor the Brood of the Bee

SUMMARY Vegetative cells ofBacillus larvaehave not produced American foul brood in healthy nuclei even when B dose almost 3000 times greater than an inoculum of spores of this organism capable of causing the disease has been sprayed over the developing brood. A very much smaller inoculum of the spores of B.larvaeis effective in producing American foul brood when the developing larvae of healthy nuclei are sprayed directly with them than when they are fed in syrup to the bees.