Lead Up to the Proposal of the Cell Theory

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Improvements to the Compound Microscope:

For a lens to be effective, it needs to do two things

Give an enlarged view of the object

Make the detail appear clear, giving a precise (not fuzzy) outline to the part of the object being viewed

Ability to enlarge an image is termed classification

Ability to show fine detail, distinguishing two very close objects as separate images is termed resolution

During the 17th the hand held tube designed by the Janssens was mounted onto a stand

The design we know today began to take shape

Robert Hooke

Robert Hooke produced the first recorded publication to describe observations of living tissue using a microscope

Coined the term 'Cell'

Hooke's findings were respected, but not universally accepted by scientists at the time

Hooke's compound microscope was progressive for its time

Microscope used a fine adjustment knob to move the tube holding the lenses up and down

Microscope also has a light source to illuminate the specimen

Robert Brown

Discovered the cell nucleus

Had no idea at the time of the importance of the nucleus or its function in cells

Travelled to Australia in 1801 and identified many genera of Australian plants

Microscopes as Valid Scientific Instruments

Added benefit of powerful light sources

Precise focusing screws

Observations made were accepted as valid scientific evidence

Shortly after this time the cell theory was proposed

Significance of Technological Advances

Without technological advances the development of the cell theory would not have happened

The main areas of advancement have been in the invention and further development in the design of the microscope

Microscope enabled us to see cells, opening doors for the development of the cell theory

The staining of cells (specimen preparation) enabled the division of the nucleus in cell division to be observed

Technological advances go hand in hand with the development of the cell theory

Evidence to Support the Cell Theory

Robert Hooke's observation of cork cells, and Leeuwenhoek's observation of many types of unicellular cells proving that living things are made up of cells

Flemming's observation of cell division - mitosis - proved that cells come from pre-existing cells