What I saw through that ultramicroscope was not an unproven theory, but a fact.
The above action can be readily demonstrated in vitro by means of the ultramicroscope.
Colloidal particles are, however, generally visible under the Zigmondy "ultramicroscope."
ultramicroscope ul·tra·mi·cro·scope (ŭl'trə-mī'krə-skōp')
A microscope with high-intensity illumination used to study very minute objects.