Charles Darwin
Charles Darwin    Planarians did not escape the attention of the great British scientist Charles Darwin (1809-1882). Darwin had the opportunity to observe and marvel over the regenerative properties of planarians during his voyage on the HMS Beagle. In fact, it was only a few days after his arrival to the American continent, in the immediacies of Rio de Janeiro (Botofogo Bay), that he encountered his first planarian specimens.

   In Chapter II of The Voyage of the Beagle (first published in 1839), Darwin wrote:

"The existence of a division of the genus Planaria, which inhabits the dry land, interested me much..."

"I found no less than twelve different species of terrestrial Planariae in different parts of the southern hemisphere. Some specimens which I obtained at Van Dieman's Land, I kept alive for nearly two months, feeding them on rotten wood. Having cut one of them transversely into two nearly equal parts, in the course of a fortnight both had the shape of perfect animals. I had, however, so divided the body, that one of the halves contained both the inferior orifices, and the other, in consequence, none. In the course of twenty-five days from the operation, the more perfect half could not have been distinguished from any other specimen. The other had increased much in size; and towards its posterior end, a clear space was formed in the parenchymatous mass, in which a rudimentary cup-shaped mouth could clearly be distinguished; on the under surface, however, no corresponding slit was yet open. If the increased heat of the weather, as we approached the equator, had not destroyed all the individuals, there can be no doubt that this last step would have completed its structure."

"Although so well known an experiment, it was interesting to watch the gradual production of every essential organ, out of the simple extremity of another animal..."

   Darwin wrote, in fact, an article on the many species of planarians he encountered in the Southern hemisphere. The paper appeared in the Annals and Magazine of Natural History (vol. XIV, p. 241-251, 1844). The plate on the right (drawn by Darwin himself) illustrated the article.
Darwin's Planarians

A comprehensive, well organized and thoroughly informative site on The Writings of Charles Darwin has been compiled by Dr. John van Wyhe.

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