_______a British Zoologist, studied different types of animal cells and reported that cells had a thin outer layer which is today known as the plasma membrane.

Answer

**Step-by-Step Solution:**

1. **Identify the Subject**: The question asks for the name of a British zoologist who studied animal cells.

2. **Recall Key Information**: The zoologist in question is known for discovering the thin outer layer of animal cells, which is referred to as the plasma membrane.

3. **Name the Zoologist**: The British zoologist who made this discovery is Theodor Schwann.

4. **Conclude the Answer**: Therefore, the complete answer to the question is: "Theodor Schwann."

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