Abstract
REFERENCE to “The Life-History of the Liver Fluke,” by A. P. Thomas (Q.J.M.S., 23, 1883), or indeed to almost any text-book in zoology, will show Mr. Stelfox that in order to become infected it is not necessary for sheep to eat the intermediate snail host of Fasciola hepatica. It suffices that the encysted cercariæ be swallowed. The latter may be found at considerable distances from their snail host, for the tailed cercariæ which give rise to the encysted forms exist as such for about a week after they have escaped from the host and are extremely active. On account of their microscopic character (they are just visible to the naked eye as snowy specks) the merest trace of water suffices for their needs. The more “watery” habitat of L. peregra, which is extremely common in all sorts of ditches, puddles, and streams, constitutes no impediment, therefore, to this snail acting as a disseminator of the liver-rot parasite granted that it can become properly infected. That it is capable of being infected and of setting free perfectly developed cercariæ I have abundant evidence.
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TAYLOR, M. Water Snails and Liver Flukes. Nature 111, 49 (1923). https://doi.org/10.1038/111049c0
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DOI: https://doi.org/10.1038/111049c0
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