353 



TYPE PROTOZOA. CLASS INFUSORIA (INFUSORY ANIMALCULES). 



Microscopic Animals One Cause of the Phosphorescence of the Sea and of the Discoloration of Water The Life in 

 Infusions Characters of the Infusoria Example of Ciliate Infusorians The Slipper Animalcules Their Construction 

 The Flagellate Order Features Cercomonas The Cilio-flagellate Infusorians Characters The Animalcules of 

 the Ponds in Phoenix Park, Dublin Melodinium Ceratium The Order Tentaculifera Characters -Achicta 

 Classification -The Ectoplasm The Endoplasm Origin of the Cilia, Flagella, and Tentacles How Infusorians Feed- 

 Action and Function of the Contractile Vesicle The Nucleus or Endoplast The Colours of Infusoria The Coloration 

 of Waters Trichocysts Reproduction by Fission, Gemmation, and otherwise Distribution TENTACULIFERA 

 SVCTORIA AGTINARIA CILIATA HOLOTRICHA Paramecium Prorodoiitidze Trachelocercidae Ichthyophthiriidse 

 Colepidaj Ophryoglenidaj Pleuronemidse Lembidae Family Discovered by Leidy Opalinidie HETEROTRICH A- 

 The Largest Infusoria Spirostomum ambif/uum Condylostoma patens Stentor polymorphusPEmimcvtAHalteria 

 yrandinellaUrocentrum turbo The "Bell" Animalcules Genera with Vorticella-like Animalcules HYPOTRICHA 

 CILIO-FLAGELLATA FLAGELLATA Noctiluca m il ia m. 



IF a glass tumbler be dipped into a pond or ditch, so as to collect some of the vegetation which is 

 found at the surface and at the sides, besides some clear water, it will invariably be found to contain 

 numerous living things, some of which are just visible to the naked eye, whilst others require a lens 

 or a compound microscope for their detection and examination. 



The larger living things are mostly in rapid movement about the water, whilst some cling to the 

 small plants and w'eed. They are usually small Crustacea, and also the larvae and active nymphs of 

 insects. Sometimes a water-spider is included in the capture, and frequently small worms are to be 

 seen. Often just visible, and moving here and there, are numerous animals which evidently produce 

 considerable currents in the water, and a lens enables the observer to distinguish that they belong to 

 species of Rotifera of the Vermes. 



But the most numerous of the dwellers in the water are either, in a few instances, just visible to 

 the unassisted eye, or are to be seen in countless numbers with the 

 aid of high magnifying powers under the compound microscope. 

 Amoeba and Gromia, minute Rhizopoda, may be found on the weed 

 or on the glass which contains the water, and little moving things 

 are visible which the botanists state are of the nature of vege- 

 tables, such, for instance, as the globe-like Volvox. But besides 

 Crustacea, Insecta, Vermes, and Rhizopoda, and vegetable 

 organisms, there are thousands of microscopic, or nearly micro- 

 scopic, animals, which are called Animalculse, or little animals, 

 and also Infusoria, or animals which live in infusions. Suppose 

 that some sea-water is collected, with a piece of seaweed in it ; 

 after a few days a host of those minute microscopic animals will 

 be found in the slime around the weed. 



On a warm summer evening, as darkness closes in, the ripples 

 of the sea become luminous, and flashes of light start from one 

 part of the harbour or coast-line, and stretch far and wide, expand- 

 ing in ever-widening circles. This particular form of phosphorescence of the sea is due to the presence 

 of myriads of minute animals, which do not belong to any of the groups of animals hitherto described 

 in this work, and which must be ranged amongst the Infusoria. Again, discoloration of fresh and salt 

 water often occurs, and it is found to be produced by crowds of microscopic creatures. In water 

 which is brackish, in water which contains a considerable quantity of salt, in water which may be icy 

 cold or very warm, and in water wliich is impregnated with foetid gas and decaying animal and 

 vegetable remains, these simple, active, wandering, or sedentary microscopic creatures, which constitute 

 the lowest forms in the animal kingdom, and which in some instances are separable only in a 

 very arbitrary manner from the simplest and lowest members of the vegetable kingdom of nature, may 

 be found in abundance. Place some of the pond water, deprived of its visibly living and 

 moving things, under a microscope with a low power, or such an one as will magnify about 

 forty times : minute bodios, hitherto invisible, are seen moving rapidly across the field of vision 

 (Fig. 1), sometimes rushing across, so that only an indefinite idea can be gleaned of their shape; or 

 283 



1. INFUSORIA IN T THE FIELD OF 

 THE MICKOSCOl'E. 



