Abstract
A Gram-positive spore bearing aerobic bacillus, isolated following accidental contamination of a saccharose broth tube, was found to grow on a saccharose agar plate as a thick soft spreading film. This film later became of semi-liquid consistency and in it the bacteria could be seen whirling about. Using a dark background preparation, the culture consisted for the most part of scarcely perceptible minute granules, often arranged in large clumps. Masses of these granules were seen in saccharose broth cultures as well as upon solid media. Using a very strong light or sunlight with the dark field microscope, these granules were also visible in strong Brownian movement. They were not stained by the usual methods. They were made visible by the following technique: a loopful of a broth culture or of an emulsion of the agar growth was mixed on a slide with a loopful of a crystal violet solution (a 1:5 or 1:10 dilution of the solution used for Gram stain). About one minute later a loopful of a 5% solution of silver nucleinate was added and the whole mixture was spread over the slide as a thin film. A second method also gave satisfactory results: the emulsion was spread over the slide, dried, stained with crystal violet without fixing, washed, covered with silver nucleinate without previously being dried, and finally the silver solution was allowed to drain off by tilting the slide. The bacteria appeared violet, the granules colorless on a brown background.
When a thick streak from a well grown culture is made on a saccharose agar plate and kept at 25°-30°C. the growth begins to spread in 15-30 minutes. With the aid of a hand lens the bacterial mass is seen to be surrounded by a thin film which spreads laterally at a rate of 2-3 mm. in an hour.
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