STUDIES ON THE MILKY DISEASE ORGANISMS

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Abstract
While living larvae of the European chafer, Amphimallon majalis Razoumowsky, permitted multiplication of vegetative cells and sporulation of B. popilliae within their blood, dead macerated larvae sterilized by heat or extracts sterilized by filtration supported growth only in the vegetative cell stages. No typical spores formed. New media and conditions devised for growth of B. popilliae maintained vegetative cells of many but not all strains in their typical parasitic morphology. No typical spores formed in the undisturbed cells. The surface of solid media is superior to liquid media for culturing the organisms, which appear preferably aerobic. Glucose, fructose, mannose, maltose, galactose, and salicin are utilized. Sucrose, although not fermented by vegetative cells isolated on artificial media, stimulates germination and growth from spore inocula. Tryptone and yeast extract satisfy at least the minimal vegetative growth requirements of the organisms for complex organic molecules and growth factors. A characteristic type of twirling motility was noted in vegetative cells of B. popilliae after several transfers on artificial media. Germination of the spores was not activated by heat. Aqueous suspensions of spores stored for one year at 1 C germinated more completely than spores freshly removed from diseased larvae.
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