Cell theory which was given by Schleiden and Schwann, did not explain as to how the new cells are formed? ................ modified the hypothesis of cell theory to give it a final shape ?

Options

A. Nageli
B. R. Virchow
C. Both (A) and (B)
D. C.P. Swanson

Answer

To answer the question regarding the modification of cell theory, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Cell Theory**: The original cell theory, proposed by Schleiden and Schwann, states that all living organisms are composed of cells, and the cell is the basic unit of life. However, it did not explain how new cells are formed.

2. **Identifying the Gap**: The gap in the original cell theory is the lack of explanation regarding the formation of new cells. This is a critical aspect of understanding cellular biology.

3. **Rudolf Virchow's Contribution**: Rudolf Virchow is the scientist who modified the original cell theory. He proposed that all cells arise from pre-existing cells, which means that new cells are formed through the division of existing cells.

4. **Evaluating the Options**:
- Option A (Nagele) is incorrect as he contributed to the concept of the cell membrane but did not address the formation of new cells.
- Option B (Rudolf Virchow) is correct because he introduced the idea that new cells come from existing cells.
- Option C (Both A and B) is incorrect since only Virchow modified the theory.
- Option D (C P Swanson) is also incorrect as he did not contribute to the modification of cell theory.

5. **Conclusion**: The correct answer is Rudolf Virchow, who modified the hypothesis of cell theory to state that new cells arise from pre-existing cells.

### Final Answer:
Rudolf Virchow modified the hypothesis of cell theory to give it a final shape by stating that new cells arise from pre-existing cells.

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