Dust and its dangers / by Mitchell Prudden.

  • Theophil Mitchell Prudden
Date:
[1890], ©1890
Catalogue details

Licence: Public Domain Mark

Credit: Dust and its dangers / by Mitchell Prudden. Source: Wellcome Collection.

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    EXPLANATION OF PLATE II. This cut shows the appearances which are presented, after the germs have grown, by paitides of sand and shreds of vegetable fibre to which single germs were clinging when they settled on to the un- covered gelatin plate. In this case the drawing was made five days after the exposure of the plate to the air of a dusty street. The largest of these colonies were barely visible to the naked eye. 1. —Shows a particle of sand completely surrounded by the colony or mass of bacteria which has grown from a single germ which was clinging to the minute sand particle as it settled with the dust. 2. —Shows a tiny shred of wood to which five different germs were attached as it settled on to the exposed plate. We should probably have searched in vain, even with a powerful microscope, for the single germs clinging to it at the time this wooden dust particle planted itself on the surface of the gelatin. But now the larger colonies are visible even to the naked eye. We know that they grew from different species of germ.j because under a moderate magnifying power they present such markedly different appearances. 3. —Shows a minute sliver to which four different forms of germs were clinging as it fell.