A microscope.
MICROSCOPE
you would use a microdissection instrument
A hydrometer is an instrument that measures the density of liquids. Auto batteries could be checked to see the strength of the acid in each cell before sealed batteries were made. I don't know of an instrument for solids or gases.
It was an extremely simple refraction microscope
You can use binoculars to see otters. You can also see them through your camera lens
microscope that see thing small.
periscope
you can't
The instrument that was necessary for Cell Theory to be developed is the microscope.
A microscope is designed to magnify very small things such as cells.
Microscope
They use microscopes, which magnify the organisms that are otherwise impossible to see.