THE MICROSCOPE
PHBIOSC 201 - Botany Lab
A good microscope is an essential tool for any
laboratory. There are many kinds of
microscopes, but the type most useful in
diagnostic work is the compound microscope.
By means of a series of lenses and a source of
bright light, it magnifies and illuminates minute
objects that would otherwise be invisible to
the eye.
The first microscope was developed in 1590 by Dutch lens grinders Hans and Zacharias Jansen. In 1667, Robert
Hooke described the microscopic appearance of cork and used the term cell to describe the compartments he
observed. Anton van Leeuwenhoek was the first person to observe living cells under the microscope in 1675—
he described many types of cells, which he named “animalcules”. Since then more sophisticated and powerful
scopes have been developed that allow for higher magnification and clearer images.
In 1830, Scottish botanist, Robert Brown identified the cell nucleus. German botanist Matthias Schleiden and
physician and physiologist Theodor Schwann have published studies that gave birth to the “Cell Theory”. The
theory states that the unit structure of living things is the cell. The German physician biologist Rudolf Virchow
expanded this theory, saying all cells came from pre-existing cells.
The Light Microscope
What does it mean to be microscopic? Objects are said to be microscopic when they are too small to be seen
with the unaided eye—they need to be magnified (enlarged) for the human eye to be able to see them. This
includes human cells and many other types of cells that you will be studying.
A. Use and Care of the Microscope
Basic Guidelines for Using the Microscope
1. Always carry the microscope with two hands.
2. Always use the microscope that is assigned to your seat number.
3. Clean the lenses with lens cleaner (Windex) and lens tissue before and after use.
4. Report any problems with the microscope to your instructor immediately.
5. Oil must be cleaned off completely before returning the microscope to the cabinet. If you accidentally get oil
on the 40X objective, clean it immediately. Microscopes must always be returned to the cabinet clean.
6. Microscopes should always be put away with a low power objective (4X or 10X) over the stage.
7. Always lift the microscope to reposition it—do not drag it across the surface of the table!
Total Magnification: The microscope you are using has two sets of lenses that both contribute to the total
magnification of the image. The ocular lenses magnify your image 10X. There are 4 different objective lenses—
each with a different magnification. The total magnification is calculated as follows:
Total magnification= ocular magnification x objective magnification
Since the ocular magnification of our microscope is 10X, determining the total magnification of an object with
this microscope simply requires multiplying the objective magnification by 10.
PHBIOSC 201 - Botany Lab
A good microscope is an essential tool for any
laboratory. There are many kinds of
microscopes, but the type most useful in
diagnostic work is the compound microscope.
By means of a series of lenses and a source of
bright light, it magnifies and illuminates minute
objects that would otherwise be invisible to
the eye.
The first microscope was developed in 1590 by Dutch lens grinders Hans and Zacharias Jansen. In 1667, Robert
Hooke described the microscopic appearance of cork and used the term cell to describe the compartments he
observed. Anton van Leeuwenhoek was the first person to observe living cells under the microscope in 1675—
he described many types of cells, which he named “animalcules”. Since then more sophisticated and powerful
scopes have been developed that allow for higher magnification and clearer images.
In 1830, Scottish botanist, Robert Brown identified the cell nucleus. German botanist Matthias Schleiden and
physician and physiologist Theodor Schwann have published studies that gave birth to the “Cell Theory”. The
theory states that the unit structure of living things is the cell. The German physician biologist Rudolf Virchow
expanded this theory, saying all cells came from pre-existing cells.
The Light Microscope
What does it mean to be microscopic? Objects are said to be microscopic when they are too small to be seen
with the unaided eye—they need to be magnified (enlarged) for the human eye to be able to see them. This
includes human cells and many other types of cells that you will be studying.
A. Use and Care of the Microscope
Basic Guidelines for Using the Microscope
1. Always carry the microscope with two hands.
2. Always use the microscope that is assigned to your seat number.
3. Clean the lenses with lens cleaner (Windex) and lens tissue before and after use.
4. Report any problems with the microscope to your instructor immediately.
5. Oil must be cleaned off completely before returning the microscope to the cabinet. If you accidentally get oil
on the 40X objective, clean it immediately. Microscopes must always be returned to the cabinet clean.
6. Microscopes should always be put away with a low power objective (4X or 10X) over the stage.
7. Always lift the microscope to reposition it—do not drag it across the surface of the table!
Total Magnification: The microscope you are using has two sets of lenses that both contribute to the total
magnification of the image. The ocular lenses magnify your image 10X. There are 4 different objective lenses—
each with a different magnification. The total magnification is calculated as follows:
Total magnification= ocular magnification x objective magnification
Since the ocular magnification of our microscope is 10X, determining the total magnification of an object with
this microscope simply requires multiplying the objective magnification by 10.
