The Origin of Species - Charles Darwin (ebook audio reader txt) 📗
- Author: Charles Darwin
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The colouring material produced generally in the superficial parts of animals. The cells secreting it are called Pigment-Cells.
PinnateBearing leaflets on each side of a central stalk.
PistilsThe female organs of a flower, which occupy a position in the centre of the other floral organs. The pistil is generally divisible into the ovary or germen, the style and the stigma.
Placentalia, PlacentataOr Placental Mammals. See Mammalia.
PlantigradesQuadrupeds which walk upon the whole sole of the foot, like the bears.
PlasticReadily capable of change.
Pleistocene PeriodThe latest portion of the Tertiary epoch.
Plumule(in plants): The minute bud between the seed-leaves of newly-germinated plants.
Plutonic RocksRocks supposed to have been produced by igneous action in the depths of the earth.
PollenThe male element in flowering plants; usually a fine dust produced by the anthers, which, by contact with the stigma effects the fecundation of the seeds. This impregnation is brought about by means of tubes (Pollen-Tubes) which issue from the pollen-grains adhering to the stigma, and penetrate through the tissues until they reach the ovary.
Polyandrous(flowers): Flowers having many stamens.
Polygamous PlantsPlants in which some flowers are unisexual and others hermaphrodite. The unisexual (male and female) flowers, may be on the same or on different plants.
PolymorphicPresenting many forms.
PolyzoaryThe common structure formed by the cells of the Polyzoa, such as the well-known seamats.
PrehensileCapable of grasping.
PrepotentHaving a superiority of power.
PrimariesThe feathers forming the tip of the wing of a bird, and inserted upon that part which represents the hand of man.
ProcessesProjecting portions of bones, usually for the attachment of muscles, ligaments, etc.
PropolisA resinous material collected by the hivebees from the opening buds of various trees.
ProteanExceedingly variable.
ProtozoaThe lowest great division of the animal kingdom. These animals are composed of a gelatinous material, and show scarcely any trace of distinct organs. The Infusoria, Foraminifera, and sponges, with some other forms, belong to this division.
Pupa(pl. Pupae): The second stage in the development of an insect, from which it emerges in the perfect (winged) reproductive form. In most insects the Pupal Stage is passed in perfect repose. The Chrysalis is the pupal state of butterflies.
RadicleThe minute root of an embryo plant.
RamusOne half of the lower jaw in the Mammalia. The portion which rises to articulate with the skull is called the Ascending Ramus.
RangeThe extent of country over which a plant or animal is naturally spread. Range in Time expresses the distribution of a species or group through the fossiliferous beds of the earth’s crust.
RetinaThe delicate inner coat of the eye, formed by nervous filaments spreading from the optic nerve, and serving for the perception of the impressions produced by light.
RetrogressionBackward development. When an animal, as it approaches maturity, becomes less perfectly organised than might be expected from its early stages and known relationships, it is said to undergo a Retrograde Development or Metamorphosis.
RhizopodsA class of lowly organised animals (Protozoa), having a gelatinous body, the surface of which can be protruded in the form of root-like processes or filaments, which serve for locomotion and the prehension of food. The most important order is that of the Foraminifera.
RodentsThe gnawing Mammalia, such as the rats, rabbits, and squirrels. They are especially characterised by the possession of a single pair of chisel-like cutting teeth in each jaw, between which and the grinding teeth there is a great gap.
RubusThe bramble genus.
RudimentaryVery imperfectly developed.
RuminantsThe group of quadrupeds which ruminate or chew the cud, such as oxen, sheep, and deer. They have divided hoofs, and are destitute of front teeth in the upper jaw.
SacralBelonging to the sacrum, or the bone composed usually of two or more united vertebrae to which the sides of the pelvis in vertebrate animals are attached.
SarcodeThe gelatinous material of which the bodies of the lowest animals (Protozoa) are composed.
ScutellaeThe horny plates with which the feet of birds are generally more or less covered, especially in front.
Sedimentary FormationsRocks deposited as sediments from water.
SegmentsThe transverse rings of which the body of an articulate animal or annelid is composed.
SepalsThe leaves or segments of the calyx, or outermost envelope of an ordinary flower. They are usually green, but sometimes brightly coloured.
SerraturesTeeth like those of a saw.
SessileNot supported on a stem or footstalk.
Silurian SystemA very ancient system of fossiliferous rocks belonging to the earlier part of the Palaeozoic series.
SpecialisationThe setting apart of a particular organ for the performance of a particular function.
Spinal CordThe central portion of the nervous system in the Vertebrata, which descends from the brain through the arches of the vertebrae, and gives off nearly all the nerves to the various organs of the body.
StamensThe male organs of flowering plants, standing in a circle within the petals. They usually consist of a filament and an anther, the anther being the essential part in which the pollen, or fecundating dust, is formed.
SternumThe breastbone.
StigmaThe apical portion of the pistil in flowering plants.
StipulesSmall leafy organs placed at the base of the footstalks of the leaves in many plants.
StyleThe middle portion of the perfect pistil, which rises like a column from the ovary and supports the stigma at its summit.
SubcutaneousSituated beneath the skin.
SuctorialAdapted for sucking.
Sutures(in the skull): The lines of junction of the bones of which the skull is composed.
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