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Shruti
- 27 Jul
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Practice Mock Test
neet
In 1868 Charles Darwin proposed Pangenesis, a developmental theory of heredity. He suggested that all cells in an organism are capable of shedding minute particles he called gemmules, which are able to circulate throughout the body and finally congregate in the gonads. These particles are then transmitted to the next generation and are responsible for the transmission of characteristics from parent to offspring. If any cells of the parent undergo changes as a result of environmental change, they will consequently transmit modified gemmules to their offspring. Soon after Darwin's pangenetic theory was published, Francis Galton designed a series of blood transfusion experiments on differently pigmented rabbits to test its validity. He found no evidence in support of the existence of Darwin's gemmules and the concept of Pangenesis was largely abandoned. In this article, recent reports of successful induction of heritable changes by blood transfusion are reviewed. Detection of circulating nucleic acids and prions in plant sap and animal blood is considered as fresh evidence for the existence of gemmules. It is now apparent that a considerable revision of views on Darwin's Pangenesis must occur before a new comprehensive genetic theory can be achieved.