Accroding to Heackel's biogenetic law :

Options

A. development of individual metazoa shows embyonic characters of ancestors
B. ontogeny repeats phylogeny
C. germplasm is immortal
D. every organism is produced by its parents

Answer

**Step-by-Step Text Solution:**

1. **Introduction to Haeckel's Biogenetic Law**: The question asks about Haeckel's biogenetic law, which is a significant concept in evolutionary biology. This law was proposed by Ernst Haeckel, a German zoologist.

2. **Understanding the Terms**:
- **Ontogeny**: This term refers to the development of an organism from the embryonic stage to its adult form. It encompasses all the changes that occur in an individual organism throughout its life cycle.
- **Phylogeny**: This term refers to the evolutionary history and relationships among species or groups of organisms. It illustrates how different species are related through common ancestry.

3. **The Law Itself**: Haeckel's biogenetic law states that "ontogeny recapitulates phylogeny." This means that the development of an individual organism (ontogeny) follows the same progression as the evolutionary history of that organism's species (phylogeny). In simpler terms, the embryonic development stages of an organism reflect the adult forms of its evolutionary ancestors.

4. **Examples**:
- In the embryonic stage, fish exhibit pharyngeal gill slits, which are structures that will develop into gills in adult fish.
- Similarly, human embryos also have pharyngeal gill slits during their development. However, in humans, these structures do not develop into functional gills; instead, they close up as development progresses.

5. **Conclusion**: The key takeaway from Haeckel's biogenetic law is that the embryonic development of an organism can show characteristics that resemble the adult forms of its evolutionary ancestors. Thus, the correct interpretation of Haeckel's law is that "ontogeny repeats phylogeny."

**Final Answer**: According to Haeckel's biogenetic law, "ontogeny recapitulates phylogeny," meaning that the development of an individual organism reflects the evolutionary history of its species.

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