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Microscopy.

(This passage was adapted from Microbiology: A Laboratory Manual, 5th edition, Cappuccino, J.S. and Sherman, N., Benjamin/Cummings Science Publishing.)

Purposes

1.To become familiar with the history and diversity of microscope instruments.

2.To understand the components, use, and care of the compound brightfield microscope.

3.To learn the correct use of the microscope for observation and measurement of microorganisms.

INTRODUCTION

Microbiology, the branch of science that has so vastly extended and expanded our knowledge of the living world, owes its existence to Antony van Leeuwenhoek. In 1673, with the aid of a crude microscope consisting of a biconcave lens enclosed in two metal plates, Leeuwenhoek introduced the world to the existence of microbial forms of life. Over the years, microscopes have evolved from the simple, single-lens instrument of Leeuwenhoek, with a magnification of 300, to the present-day electron microscopes capable of magnifications greater than 250,000. Microscopes are designated as either light microscopes or electron microscopes. The former use visible light or ultraviolet rays to illuminate specimens. They include brightfield, darkfield, phase-contrast, and fluorescent instruments. Fluorescent micro-scopes use ultraviolet radiations whose wavelengths are shorter than those of visible light and are not directly perceptible to the human eye. Electron microscopes use elec-tron beams instead of light rays, and magnets instead of lenses to observe submicro-scopic particles.

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