In the developmental history of mammalian heart. It is observed that it passes through a two chambered fish like heart, three chambered frog like heart and finally four chambered stage. To which hypothesis can this above cited statement be approximated?

Options

A. Lamarchk's principle
B. Mendelian principles
C. Biogenetic law
D. Hardy Weinberg law

Answer

To answer the question regarding the developmental history of the mammalian heart and its resemblance to earlier evolutionary stages, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Developmental Stages**:
- The mammalian heart develops through stages that resemble the hearts of lower vertebrates: first a two-chambered heart (like that of fish), then a three-chambered heart (like that of frogs), and finally a four-chambered heart (characteristic of mammals).

2. **Identifying Relevant Hypotheses**:
- We need to determine which hypothesis best explains this observation. The options include:
- Lamarckian principle
- Mendelian principle
- Biogenetic law
- Hardy-Weinberg principle

3. **Evaluating Each Hypothesis**:
- **Lamarckian Principle**: This principle suggests that acquired traits can be inherited. However, it does not explain the sequential development of heart structures in embryos.
- **Mendelian Principle**: This principle focuses on the laws of inheritance and does not pertain to the developmental stages of the heart.
- **Biogenetic Law**: Proposed by Ernst Haeckel, this law states that the development of an organism (ontogeny) follows the same progression as its evolutionary history (phylogeny). This suggests that the embryonic development reflects the evolutionary stages of the organism.
- **Hardy-Weinberg Principle**: This principle deals with genetic equilibrium in populations and does not relate to the development of individual organisms.

4. **Conclusion**:
- The correct hypothesis that aligns with the observation of the mammalian heart's development through stages resembling those of fish and frogs is the **Biogenetic Law**. This law indicates that the embryonic development stages reflect the evolutionary history of the organism.

### Final Answer:
The developmental history of the mammalian heart, passing through stages of a two-chambered fish-like heart, a three-chambered frog-like heart, and finally a four-chambered heart, can be approximated to the **Biogenetic Law** proposed by Ernst Haeckel.