The size of common objects 
as viewed under 
microscopes. 
Actual size 
Hen egg 
Hummingbird egg 
Magnified 100 times 
Human egg 
Human egg 
superimposed 
on amoeba 
• Human liver cell 
• Influenza bacillus 
Magnified 10,000 times 
Pneumococcus bacterium 
Hemoglobin molecule 
compounds that are absorbed 
to differing extents by various 
cell parts. The cell sections 
also had to be “fixed” in new 
ways, to preserve them, and 
had to be embedded in new 
kinds of materials (mostly 
transparent plastic). 
Altogether, it was not until 
the early 1950’s that electron 
microscopes began to be used 
routinely for cell biological 
studies. While microscopists 
were looking through their 
instruments at smaller and 
smaller particles in cells and 
attempting to understand 
their structure, another group 
of scientists was pursuing an 
entirely different, but equally 
important, line of research — 
biochemistry. 
Unit 
Equal to 
Used to Measure 
Centimeter 
1/100 meter 
Objects visible to the eye 
Millimeter 
1/10 centimeter 
Very large cells 
Micrometer (micron) 
1/1000 millimeter 
Most cells, large organelles 
Nanometer 
1/1000 micrometer 
Small organelles, large molecules 
Angstrom 
1/10 nanometer 
Molecules, atoms 
