"Observations on Some Interesting Phaenomena in Animal Physiology Exhibited by Several Species of Planariae" written by J.G. Dalyell was published in Edinburgh in 1814. Perhaps the first experimental approach to planarian regeneration, this monograph reports Dalyell's efforts to reproduce experimentally an anomaly he had observed in wild planarians. In his own words:
"...the planaria in relation to others was of small size, its tail was bifid, and out of the cleft grew a body, separated and distinct from the main trunk of the animal, which by some strange and anomalous proceeding had been surmounted by a head, lively and well defined...In the course of a week or little more the posterior head had separated by spontaneous division and had disappeared. But soon afterwards a kind of projection occupied its place; and it was not without amazement that I beheld this projection vegetate into a new head, resembling the one which had been lost. About a month having elapsed, it was well shaped and entire. My belief being thus corroborated in the probable effect of experiment, it was reasonable to conclude, that if separating parts became complete animals, if a mutilated trunk regained the defective portion; and if a head, the most important of all organs, was evolved from every inconsiderable fragment, supernumerary parts might, by some particular operation, be produced; yet it was long before reiterated trials were rewarded with success, and I had almost determined to abandon the enquiry, conceiving that a certain nicety, of which I was not master, should be practised, and that it had been beyond my ability to detect the secret cause of failure."
Later, J. R. Johnson would repeat and confirm Dalyell's experiments and he would publish his accounts in the Philosophical Transactions of the Royal Society of London in 1825 (part II, pp.247-256).
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