Define theory of cell lineage.

Explanation

**Step-by-Step Solution:**

1. **Understanding the Concept**: The theory of cell lineage is a fundamental biological concept that explains how new cells are formed.

2. **Definition**: The theory of cell lineage states that all cells arise from pre-existing cells. This means that no new cells can be created spontaneously; they must come from the division of existing cells.

3. **Omnicellular Acellular Principle**: The term "Omnicellular Acellular" emphasizes that every cell in an organism originates from another cell, reinforcing the idea that cellular life is interconnected through division.

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