. Diseases of bees. Bees. Apr. 12,1924 Development of American Foulbrood 139 added to each tube and it is then slanted. Series of agar slants varying in sugar concentration are inoculated with either vegetative cultures or diseased material containing only spores. To determine spore germination an approximately uniform amount, about one 2-mm. loopful of ropy material, when available, is used for inoculation of slants, otherwise a scale softened as described above. If no visible growth takes place after 48 hours' incubation, stained smears are made, to determine whether any germination has occu
. Diseases of bees. Bees. Apr. 12,1924 Development of American Foulbrood 139 added to each tube and it is then slanted. Series of agar slants varying in sugar concentration are inoculated with either vegetative cultures or diseased material containing only spores. To determine spore germination an approximately uniform amount, about one 2-mm. loopful of ropy material, when available, is used for inoculation of slants, otherwise a scale softened as described above. If no visible growth takes place after 48 hours' incubation, stained smears are made, to determine whether any germination has occurred. In the case of the determination of growth from vegetative culture, a single uniform streak is made on the agar slant, using one 2-mm. loopful of growth from a 48-hour cul- ture of Bacillus larvae prevously isolated and cultivated. After 48 hours' incubation, as well as after about one week, comparative observations are made of the relative amount and character of the growth. Where little or no growth has occurred, stained smears are made from the streak to see what has happened to the organisms. These experiments were carried out with a number of different strains of vegetative cultures and from a number of different samples of American Fig. 9.—Partially decom- posed American foulbrood larva at the stage of ropy consistency. (White C55)) Table I.—The effect of varying the sugar concentration in egg-yolk suspension medium (1) on germination and vegetative growth from spores; and {2) on vege- tative growth from vigorous vegetative cultures of Bacillus larvae. <» Test material Per cent dextrose in medium Control Spores _ Vegetative cultures- ++++ ++ +++ +++ +++ ++++ ++++ ++++ ++++ +++ ++++ +++ ++ +++ +++ Per cent dextrose in medium Test material Spores ._ Vegetative cultures- + ++ + ++ + ++ + ++ o Tbe following symbols are used: + Slight growth. ++ Fair growth. +++ Good growth. ++++ Heavy growth.
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