The biogenetic law of Haeckel is

Options

A. Omnis vivum e vivum
B. Omnis cellula e cellula
C. Ontogency repeats phylogency
D. Phylogency repeats ontogeny

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks about the biogenetic law proposed by Ernst Haeckel. This law is also known as the recapitulation theory.

2. **Definition of Key Terms**:
- **Ontogeny**: This term refers to the development of an individual organism from the fertilization of the egg to its mature form. It includes all the embryonic stages.
- **Phylogeny**: This refers to the evolutionary history of a species or group of related organisms. It traces the lineage and evolutionary changes over time.

3. **Haeckel's Biogenetic Law**: According to Haeckel's biogenetic law, "ontogeny recapitulates phylogeny." This means that during the development of an organism (ontogeny), it goes through stages that resemble the adult forms of its evolutionary ancestors (phylogeny).

4. **Analyzing the Options**:
- **Omnis vivum evum**: This phrase means "all life comes from pre-existing life," attributed to Louis Pasteur. This is incorrect in the context of Haeckel's law.
- **Omnis cellula ecellula**: This means "all cells come from pre-existing cells," proposed by Rudolf Virchow. This is also not related to Haeckel's biogenetic law.
- **Ontogeny repeats phylogeny**: This is the correct statement of Haeckel's biogenetic law.
- **Phylogeny repeats ontogeny**: This statement is incorrect as it reverses the relationship described by Haeckel.

5. **Conclusion**: The correct answer to the question is that the biogenetic law of Haeckel states that "ontogeny repeats phylogeny."

### Final Answer:
The biogenetic law of Haeckel is: **"Ontogeny repeats phylogeny."**

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