According to the understanding in the early 1890s, what size class of organisms were Chamberland filters designed to stop?

Answer

All known living organisms of that size (bacteria)

In 1892, the fine porcelain filters were considered impermeable to all known bacteria, meaning any infectious agent passing through was assumed to be smaller than a bacterium or not truly 'living' by the established definition.

According to the understanding in the early 1890s, what size class of organisms were Chamberland filters designed to stop?
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