Metamorphoses of man and the lower animals / by A. de Quatrefages ; translated by Henry Lawson.

Date:
1864
Catalogue details

Licence: Public Domain Mark

Credit: Metamorphoses of man and the lower animals / by A. de Quatrefages ; translated by Henry Lawson. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

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    experiments; so tliat iiow_, thanks to tlie number of their works^ we can trace^ if not tlie special history of each species_, at all events^ the general history of these beings^ which in former days were looked on as such mysteries. In the first place^ let us treat of the Trematodes. We shall select^ as an example^ one of the species akin to the Monostomum midahile, or the Distomum militare/^ which have been investigated by both Siebold and Van Beneden. The general description of trematodes already given will suffice to convey an idea of these animals. They may be described as little leeches, inhabiting the bodies of fresh-water mollusks. In the bodies of these hel- minthes hundreds of ova may be found, whose vitelli have already undergone their first transformations, and have become ciliated larv£e. These latter leave their envelopes, and, thus set free, make their way into the bodies of mollusks hj some means or other. There they remain, and appear to undergo destruction, whilst in their places are left a number of very small ovoid bodies, which have been developed within them. Each of these bodies, which were regarded as necessary parasites by the German authors, and as enigmatical organs by P. Dujardin, increases in size, elongates, and acquires two lateral appendages pos- teriorly. This is the s]jorocyst of Baer, the redie of Filippi.f Judging by its movements, and its well- * The Distoiiiiini and Monostomum are genera belonging to tlie Trematode group. f It lias been very reasonably proposed by Filippi to distinguish the transitional beings by giving them different names, according as they present a more or less complex organization, or rather