Darwin's theory of pangenesis proposes

Options

A. Development of useful organs and degeneration of uselss organs
B. Development of an organ due to will power
C. Increase in organ size with age
D. Every organ of the body produces minute hereditary particles called gemmules, carried through the blood from every organ and collected together into gametes.

Answer

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

1. **Introduction to Darwin and His Contributions**: Charles Darwin was an English naturalist known for his foundational work in the field of evolution. His most notable publication, "On the Origin of Species," released in 1859, introduced concepts such as natural selection, struggle for existence, and variation.

2. **Weaknesses in Darwin's Original Theory**: Despite the groundbreaking nature of his work, Darwin's theory had certain weaknesses. One of the main issues was that he could not adequately explain the cause of discontinuous variation, which refers to traits that appear in distinct categories rather than a continuous range. Additionally, he struggled to explain how these variations were transmitted to the next generation.

3. **Introduction of the Theory of Pangenesis**: To address these gaps in his original theory, Darwin proposed the theory of pangenesis in 1868. This theory aimed to explain how variations could arise and be passed on to offspring.

4. **Key Concepts of Pangenesis**: According to the theory of pangenesis, every organ in the body produces tiny hereditary particles known as "pangenes" or "gemmules." These particles are thought to be responsible for carrying genetic information. They are released into the bloodstream and eventually reach the reproductive cells (gametes), thereby influencing the traits of the next generation.

5. **Rejection of Pangenesis**: Although Darwin's theory of pangenesis was an attempt to explain heredity, it was later rejected by other scientists, notably by August Weismann in 1892. Weismann proposed the theory of germplasm, which provided a more accurate understanding of heredity and the role of germ cells.

6. **Conclusion**: In summary, Darwin's theory of pangenesis proposed that every organ produces minute hereditary particles (pangenes) that are carried through the blood to the gametes, influencing the traits of future generations. However, this theory was ultimately rejected in favor of more robust explanations of heredity.

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