. Text-book of zoology for junior students. Zoology. INFUSORIA. 39 Paramoecium (fig. 18) ia a beautiful .slipper-shaped little creature, which may be found commonly in stagnant waters or in artificially prepared infusions. The body is nearly quite transparent, and con- sists of three layers—1, a structureless, transparent, external film or pellicle, called the " cuticle " ; 2, a central mass of soft semi-fluid sarcode which receives the particles of food; and .3, an intermedi- ate layer of firm and consistent sarcode, which is called the " cortical layer" (Lat. cortex, bark
. Text-book of zoology for junior students. Zoology. INFUSORIA. 39 Paramoecium (fig. 18) ia a beautiful .slipper-shaped little creature, which may be found commonly in stagnant waters or in artificially prepared infusions. The body is nearly quite transparent, and con- sists of three layers—1, a structureless, transparent, external film or pellicle, called the " cuticle " ; 2, a central mass of soft semi-fluid sarcode which receives the particles of food; and .3, an intermedi- ate layer of firm and consistent sarcode, which is called the " cortical layer" (Lat. cortex, bark). The external mem- brane or cuticle is richly covered with minute vibrating hairs or cilia, which in this particular type are of approxi- mately equal length, and are arranged in close-set longitudinal rows. In many of the Infusoria, however, the cilia in the neighbourhood of the mouth are much longer than those covering the general surface. The cuticle is also per- forated by the aperture of the mouth, which is continued into a short funnel- shaped gullet (fig. 18, m g). The gullet, however, is not continued into any dis- tinct stomach, but opens directly into the soft semi-fluid sarcode (endoplasm) which constitutes the central mass of the body. The particles of food on passing through the gullet are directly received into the central mass of dif- fluent sarcode, where they undergo a kind of slow circulation or rotation. As in the case of the Amosha, each par- ticle of food generally carries with it a little water, so that the appearance is rjvoduced of a number of little clear Fig. \%.—Parama:cinm., viewed dorsally, and greatly magnified, m Moutii; m to g GuUet: a Anus ; cv' and cv Tlie contractile vesicles; T, II, III, Canals iiroceeding from the anterior contractile vesicle ; n Nucleus; v Large cilia bounding the de- pression (" vestibule ") leading to the luouth. The arrows indicate the course in which the itarticles of food circulate in the semi-fluid pro
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectzoology, bookyear1885
