Who proposed for the first time that cells are totipotent ?

Options

A. White
B. Haberlandt
C. Steward
D. Halperin and Wetherell

Answer

To answer the question "Who proposed for the first time that cells are totipotent?", we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Totipotency**:
- Totipotent cells are those that have the potential to develop into a complete organism. This means they can give rise to all cell types, including both the embryonic and extra-embryonic tissues.

2. **Identifying the Scientists**:
- The question provides four options: A. White, B. Humberland, C. Stewart, and D. Halperin and Wetherlyd.

3. **Researching the Contributions**:
- It is essential to know the contributions of each scientist regarding totipotency.
- Humberland (often spelled Haberland) is known for his work in plant tissue culture and is credited with the concept of totipotency in plant cells.

4. **Eliminating Incorrect Options**:
- White is known for his work on callus growth but did not propose the concept of totipotency.
- Stewart and Halperin and Wetherlyd are not primarily associated with the concept of totipotency.

5. **Conclusion**:
- Based on the information gathered, the scientist who first proposed that cells are totipotent is **B. Humberland**.

### Final Answer:
The correct answer is **B. Humberland**.