A general history of animalcules .... Being part I of 'A history of infusoria, living and fossil' / [Andrew Pritchard].

  • Andrew Pritchard
Date:
1843
Catalogue details

Licence: Public Domain Mark

Credit: A general history of animalcules .... Being part I of 'A history of infusoria, living and fossil' / [Andrew Pritchard]. Source: Wellcome Collection.

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    shell-less, or illoricated Infusoria, whilst the latter denotes the loricated. I shall, therefore, ado])t the terms loricated and illoricated in this work, because they appear to be the least objectionable ; for, although, in etymological strict¬ ness, lorica simply means a shell, yet, as we commonly attach the idea of a certain composition to the word shell, it may be as well to avoid the use of it, for the following reasons:— The Lorica differs greatly as to its composition in different species. In some cases it is composed entirely of silica; in others, of lime, with a portion of the oxide of iron. In some, it is combustible; in others, not so. There is a difference also as to the proportion of envelope- ment of the creature within the lorica. Some Infusoria are entirely encased, as in a box or pitcher; whilst others are only so in part, having merely a shield or carapace over them. In the latter, the covering resembles that of the Chilonia or turtle tribe. As, in very minute genera, it is often difficult to ascer¬ tain, by a mere inspection, whether they are enclosed within a lorica or not, it will not be deemed uninteresting to point out the manner in which this may be determined. Having obtained some specimens of the Infusoria, we will suppose of the family Cryptomonas {Jigs. 21 to 33), place a drop of water containing them in an aquatic live-box, compressor, or crush-box, mixing a little colouring matter with the water, according to the directions given in the section “ On feeding Animalcules with coloured Mate¬ rials f when, if loricated, a clear transjiarent ring will be observed, encircling the animalcules, and keeping them separate from the fluid in which they are immersed :—