Name the device which has made the study of microorganism successful.

Explanation

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for the name of a device that has facilitated the successful study of microorganisms.

2. **Identifying the Device**: The primary device used for studying microorganisms is the microscope. There are different types of microscopes, including light microscopes and electron microscopes.

3. **Function of the Microscope**: Microscopes allow us to magnify small organisms that are not visible to the naked eye. This magnification enables scientists to observe and study the structure and behavior of microorganisms in detail.

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