Name the scientist who modified the cell theory given by Schleiden and Schwann.

Explanation

**Step-by-Step Solution:**

1. **Understanding the Original Cell Theory**: The original cell theory was proposed by scientists Matthias Schleiden and Theodor Schwann in 1839. It consisted of two main points:
- All living organisms are composed of one or more cells.
- The cell is the basic structural and functional unit of life.

2. **Identifying the Limitation**: While Schleiden and Schwann's cell theory was foundational, it had a significant limitation. They did not explain how cells arise or where they come from, making the theory incomplete.

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