. Pathogenic micro-organisms, including bacteria and Protozoa; a practical manual for students, physicians and health officers. long and numerous; short forms actively motile; threadsimmotile. Spore Formation.—Oval spores formed in presence of air germinating atright angles to long diameter. Spores are set free in about 24 hours, size ; widely distributed in nature, dust, air, excreta, etc., (see Fig. 62). Biology: Cultural Characters (Including Biochemical Features).—Bou-illon.—Uniformly cloudy growth with marked pellicle, wrinkled and thick;copious spore formation. Gelatine Plates
. Pathogenic micro-organisms, including bacteria and Protozoa; a practical manual for students, physicians and health officers. long and numerous; short forms actively motile; threadsimmotile. Spore Formation.—Oval spores formed in presence of air germinating atright angles to long diameter. Spores are set free in about 24 hours, size ; widely distributed in nature, dust, air, excreta, etc., (see Fig. 62). Biology: Cultural Characters (Including Biochemical Features).—Bou-illon.—Uniformly cloudy growth with marked pellicle, wrinkled and thick;copious spore formation. Gelatine Plates and Tubes.—Saucer-like depressions; colonies have granu-lar centres and folded margins. Surface growth in stab cultures is whitish-gray; colonies sink on liquefaction of medium; liquefaction progresses iu acylindrical form, and a thick white scum is formed. Agar Plates and Tubes.—Small, irregular, grayish-white colonies; moistglistening growth along needle track in stab cultures. The bacteria in taking certain atoms from the molecules utilizedin their growth leave the other atoms to enter into new relations and. THE SOIL BACTERIA AND THEIR FUNCTIONS. 97 form new compounds. The actual products will depend on thedecaying substance, the variety of bacteria and the conditions —This is a process of oxidation by which throughbacterial activities ammonia compounds are changed to nitrates andthus rendered utihzable by plants. This change is accomplished intwo stages; first, the ammonia is oxidized to nitrite and second tonitrate. The nitrates are taken up by the plant roots from the bacterial nature of these changes were discovered in 1877 bytwo French investigators, Schlosing and Muntz. They noted thatfermenting sewage after a time lost its ammonia and gained in nitrates,but that if the sewage was treated with antiseptics, so that fermentationceased, no such change occurred. War- ^^^ ^^ rington first and Winogradsky later morethoroughly inves
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