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Preface
Introduction
Chapter 1 - Variation Under
Domestication
Chapter 2 - Variation Under
Nature
Chapter 3 - Struggle for Existence
Chapter 4 - Natural Selection
Chapter 5 - Laws of Variation
Chapter 6 - Difficulties on
Theory
Chapter 7 - Instinct
Chapter 8 - Hybridism
Chapter 9 - On the Imperfection
of the Geological Record
Chapter 10 - On The Geological
Succession of Organic Beings
Chapter 11 - Geographical Distribution
Chapter 12 - Geographical Distribution
continued
Chapter 13 - Mutual Affinities
of Organic Beings:
Morphology: Embryology: Rudimentary Organs
Chapter 14 - Recapitulation
and Conclusion
Glossary
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 Glossary
I am indebted to the kindness of Mr. W. S. Dallas
for this Glossary, which has been given because several
readers have complained to me that some of the terms used
were unintelligible to them. Mr. Dallas has endeavoured
to give the explanations of the terms in as popular a form
as possible.
EDITOR'S NOTE: This glossary did not appear in
the first edition and has been reproduced here directly
from the sixth edition
- *
ABERRANT
- Forms or groups of animals or plants which deviate
in important characters from their nearest allies, so
as not to be easily included in the same group with them,
are said to be aberrant.
- *
ABERRATION (in Optics)
- In the refraction of light by a convex lens the rays
passing through different parts of the lens are brought
to a focus at slightly different distances, this is called
spherical aberration; at the same time the coloured
rays are separated by the prismatic action of the lens
and likewise brought to a focus at different distances,
this is chromatic aberration.
- *
ABNORMAL
- Contrary to the general rule.
- *
ABORTED
- An organ is said to be aborted, when its development
has been arrested at a very early stage.
- *
ALBINISM
- Albinos are animals in which the usual colouring matters
characteristic of the species have not been produced in
the skin and its appendages. Albinism is the state of
being an albino.
- *
ALGAE
- A class of plants including the ordinary sea-weeds
and the filamentous fresh-water weeds.
- *
ALTERNATION OF GENERATIONS
- This term is applied to a peculiar mode of reproduction
which prevails among many of the lower animals, in which
the egg produces a living form quite different from its
parent, but from which the parent-form is reproduced by
a process of budding, or by the division of the substance
of the first product of the egg.
- *
AMMONITES
- A group of fossil, spiral, chambered shells, allied
to the existing pearly Nautilus, but having the partitions
between the chambers waved in complicated patterns at
their junction with the outer wall of the shell.
- *
ANALOGY
- That resemblance of structures which depends upon similarity
of function, as in the wings of insects and birds. Such
structures are said to be analogous, and to be
analogues of each other.
- *
ANIMALCULE
- A minute animal: generally applied to those visible
only by the microscope.
- *
ANNELIDS
- A class of worms in which the surface of the body exhibits
a more or less distinct division into rings or segments,
generally provided with appendages for locomotion and
with gills. It includes the ordinary marine worms, the
earthworms, and the leeches.
- *
ANTENNÆ
- Jointed organs appended to the head in Insects, Crustacea
and Centipedes, and not belonging to the mouth.
- *
ANTHERS
- The summits of the stamens of flowers, in which the
pollen or fertilising dust is produced.
- *
APLACENTALIA,
APLACENTATA or Aplacental Mammals
- See Mammalia.
- *
ARCHETYPAL
- Of or belonging to the Archetype, or ideal primitive
form upon which all the beings of a group seem to be organised.
- *
ARTICULATA
- A great division of the Animal Kingdom characterised
generally by having the surface of the body divided into
rings called segments, a greater or less number of which
are furnished with jointed legs (such as Insects, Crustaceans
and Centipedes).
- *
ASYMMETRICAL
- Having the two sides unlike.
- *
ATROPHIED
- Arrested in development at a very early stage.
- *
BALANUS
- The genus including the common Acorn-shells which live
in abundance on the rocks of the sea-coast.
- *
BATRACHIANS
- A class of animals allied to the Reptiles, but undergoing
a peculiar metamorphosis, in which the young animal is
generally aquatic and breathes by gills. (Examples,
Frogs, Toads, and Newts.)
- *
BOULDERS
- Large transported blocks of stone generally imbedded
in clays or gravels.
- *
BRACHIOPODA
- A class of marine Mollusca, or soft-bodied animals,
furnished with a bivalve shell, attached to submarine
objects by a stalk which passes through an aperture in
one of the valves, and furnished with fringed arms, by
the action of which food is carried to the mouth.
- *
BRANCHIÆ
- Gills or organs for respiration in water.
- *
BRANCHIAL
- Pertaining to gills or branchiæ.
- *
CAMBRIAN SYSTEM
- A Series of very ancient Palæozoic rocks, between
the Laurentian and the Silurian. Until recently these
were regarded as the oldest fossiliferous rocks.
- *
CANIDÆ
- The Dog-family, including the Dog, Wolf, Fox, Jackal,
&c.
- *
CARAPACE
- The shell enveloping the anterior part of the body
in Crustaceans generally; applied also to the hard shelly
pieces of the Cirripedes.
- *
CARBONIFEROUS
- This term is applied to the great formation which includes,
among other rocks, the coal-measures. It belongs to the
oldest, or Palæozoic, system of formations.
- *
CAUDAL
- Of or belonging to the tail.
- *
CEPHALOPODS
- The highest class of the Mollusca, or Soft-bodied animals,
characterised by having the mouth surrounded by a greater
or less number of fleshy arms or tentacles, which, in
most living species, are furnished with sucking-cups.
(Examples, Cuttle-fish, Nautilus.)
- *
CETACEA
- An order of Mammalia, including the Whales, Dolphins,
&c., having the form of the body fish-like, the skin
naked, and only the fore-limbs developed.
- *
CHELONIA
- An order of Reptiles including the Turtles, Tortoises,
&c.
- *
CIRRIPEDES
- An order of Crustaceans including the Barnacles and
Acorn-shells. Their young resemble those of many other
Crustaceans in form; but when mature they are always attached
to other objects, either directly or by means of a stalk,
and their bodies are enclosed by a calcareous shell composed
of several pieces, two of which can open to give issue
to a bunch of curled, jointed tentacles, which represent
the limbs.
- *
COCCUS
- The genus of Insects including the Cochineal. In these
the male is a minute, winged fly, and the female generally
a motionless, berry-like mass.
- *
COCOON
- A case usually of silky material, in which insects
are frequently enveloped during the second or resting-stage
(pupa) of their existence. The term `cocoon-stage' is
here used as equivalent to `pupa-stage.'
- *
COELOSPERMOUS
- A term applied to those fruits of the Umbelliferæ
which have the seed hollowed on the inner face.
- *
COLEOPTERA
- Beetles, an order of Insects, having a biting mouth
and the first pair of wings more or less horny, forming
sheaths for the second pair, and usually meeting in a
straight line down the middle of the back.
- *
COLUMN
- A peculiar organ in the flowers of Orchids, in which
the stamens, style and stigma (or the reproductive parts)
are united.
- *
COMPOSITÆ
or COMPOSITOUS PLANTS
- Plants in which the inflorescence consists of numerous
small flowers (florets) brought together into a dense
head, the base of which is enclosed by a common envelope.
(Examples, the Daisy, Dandelion, &c.)
- *
CONFERVÆ
- The filamentous weeds of fresh water.
- *
CONGLOMERATE
- A rock made up of fragments of rock or pebbles, cemented
together by some other material.
- *
COROLLA
- The second envelope of a flower usually composed of
coloured, leaf-like organs (petals), which may be united
by their edges either in the basal part or throughout.
- *
CORRELATION
- The normal coincidence of one phenomenon, character,
&c., with another.
- *
CORYMB
- A bunch of flowers in which those springing from the
lower part of the flower stalk are supported on long stalks
so as to be nearly on a level with the upper ones.
- *
COTYLEDONS
- The first or seed-leaves of plants.
- *
CRUSTACEANS
- A class of articulated animals, having the skin of
the body generally more or less hardened by the deposition
of calcareous matter, breathing by means of gills. (Examples,
Crab, Lobster, Shrimp, &c.)
- *
CURCULIO
- The old generic term for the Beetles known as Weevils,
characterised by their four-jointed feet, and by the head
being produced into a sort of beak, upon the sides of
which the antennæ are inserted.
- *
CUTANEOUS
- Of or belonging to the skin.
- *
DEGRADATION
- The wearing down of land by the action of the sea or
of meteoric agencies.
- *
DENUDATION
- The wearing away of the surface of the land by water.
- *
DEVONIAN SYSTEM
or formation
- A series of Palæozoic rocks, including the Old
Red Sandstone.
- *
DICOTYLEDONS
or DICOTYLEDONOUS PLANTS
- A class of plants characterised by having two seed-leaves,
by the formation of new wood between the bark and the
old wood (exogenous growth) and by the reticulation of
the veins of the leaves. The parts of the flowers are
generally in multiples of five.
- *
DIFFERENTIATION
- The separation or discrimination of parts or organs
which in simpler forms of life are more or less united.
- *
DIMORPHIC
- Having two distinct forms. Dimorphism is the condition
of the appearance of the same species under two dissimilar
forms.
- *
DIOECIOUS
- Having the organs of the sexes upon distinct individuals.
- *
DIORITE
- A peculiar form of Greenstone.
- *
DORSAL
- Of or belonging to the back.
- *
EDENTATA
- A peculiar order of Quadrupeds, characterised by the
absence of at least the middle incisor (front) teeth in
both jaws. (Examples, the Sloths and Armadillos.)
- *
ELYTRA
- The hardened fore-wings of Beetles, serving as sheaths
for the membranous hind-wings, which constitute the true
organs of flight.
- *
EMBRYO
- The young animal undergoing development within the
egg or womb.
- *
EMBRYOLOGY
- The study of the development of the embryo.
- *
ENDEMIC
- Peculiar to a given locality.
- *
ENTOMOSTRACA
- A division of the class Crustacea, having all the segments
of the body usually distinct, gills attached to the feet
or organs of the mouth, and the feet fringed with fine
hairs. They are generally of small size.
- *
EOCENE
- The earliest of the three divisions of the Tertiary
epoch of geologists. Rocks of this age contain a small
proportion of shells identical with species now living.
- *
EPHEMEROUS INSECTS
- Insects allied to the May-fly.
- *
FAUNA
- The totality of the animals naturally inhabiting a
certain country or region, or which have lived during
a given geological period.
- *
FELIDÆ
- The Cat-family.
- *
FERAL
- Having become wild from a state of cultivation or domestication.
- *
FLORA
- The totality of the plants growing naturally in a country,
or during a given geological period.
- *
FLORETS
- Flowers imperfectly developed in some respects, and
collected into a dense spike or head, as in the Grasses,
the Dandelion, &c.
- *
FOETAL
- Of or belonging to the foetus, or embryo in course
of development.
- *
FORAMINIFERA
- A class of animals of very low organisation, and generally
of small size, having a jelly-like body, from the Surface
of which delicate filaments can be given off and retracted
for the prehension of external objects, and having a calcareous
or sandy shell, usually divided into chambers, and perforated
with small apertures.
- *
FOSSILIFEROUS
- Containing fossils.
- *
FOSSORIAL
- Having a faculty of digging. The Fossorial Hymenoptera
are a group of Wasp-like Insects, which burrow in sandy
soil to make nests for their young.
- *
FRENUM (pl
- FRENA). A small band or fold of skin.
- *
FUNGI (Sing
- FUNGUS). A class of cellular plants, of which Mushrooms,
Toadstools, and Moulds, are familiar examples.
- *
FURCULA
- The forked bone formed by the union of the collarbones
in many birds, such as the common Fowl.
- *
GALLINACEOUS BIRDS
- An order of Birds of which the common Fowl, Turkey,
and Pheasant, are well-known examples.
- *
GALLUS
- The genus of birds which includes the common Fowl.
- *
GANGLION
- A swelling or knot from which nerves are given off
as from a centre.
- *
GANOID FISHES
- Fishes covered with peculiar enamelled bony scales.
Most of them are extinct.
- *
GERMINAL VESICLE
- A minute vesicle in the eggs of animals, from which
development of the embryo proceeds.
- *
GLACIAL PERIOD
- A period of great cold and of enormous extension of
ice upon the surface of the earth. It is believed that
glacial periods have occurred repeatedly during the geological
history of the earth, but the term is generally applied
to the close of the Tertiary epoch, when nearly the whole
of Europe was subjected to an arctic climate.
- *
GLAND
- An organ which secretes or separates some peculiar
product from the blood or sap of animals or plants.
- *
GLOTTIS
- The opening of the windpipe into the oesophagus or
gullet.
- *
GNEISS
- A rock approaching granite in composition, but more
or less laminated, and really produced by the alteration
of a sedimentary deposit after its consolidation.
- *
GRALLATORES
- The so-called Wading-birds (Storks, Cranes, Snipes,
&c.), which are generally furnished with long legs,
bare of feathers above the heel, and have no membranes
between the toes.
- *
GRANITE
- A rock consisting essentially of crystal of felspar
and mica in a mass of quarts.
- *
HABITAT
- The locality in which a plant or animal naturally lives.
- *
HEMIPTERA
- An order or sub-order of Insects, characterised by
the possession of a jointed beak or rostrum, and by having
the fore-wings horny in the basal portion and membranous
at the extremity, where they cross each other. This group
includes the various species of Bugs.
- *
HERMAPHRODITE
- Possessing the organs of both sexes.
- *
HOMOLOGY
- That relation between parts which results from their
development from corresponding embryonic parts, either
in different animals, as in the case of the arm of man,
the foreleg of a quadruped, and the wing of a bird; or
in the same individual, as in the case of the fore and
hind legs in quadrupeds, and the segments or rings and
their appendages of which the body of a worm, a centipede,
&c., is composed. The latter is called serial homology.
The parts which stand in such a relation to each other
are said to be homologous, and one such part or
organ is called the homologue of the other. In
different plants the parts of the flower are homologous,
and in general these parts are regarded as homologous
with leaves.
- *
HOMOPTERA
- An order or sub-order of Insects having (like the Hemiptera)
a jointed beak, but in which the fore-wings are either
wholly membranous or wholly leathery. The Cicadoe,
Frog-hoppers, and Aphides, are well-known examples.
- *
HYBRID
- The offspring of the union of two distinct species.
- *
HYMENOPTERA
- An order of insects possessing biting jaws and usually
four membranous wings in which there are a few veins.
Bees and Wasps are familiar examples of this group.
- *
HYPERTROPHIED
- Excessively developed.
- *
ICHNEUMONIDÆ
- A family of Hymenopterous insects, the members of which
lay their eggs in the bodies or eggs of other insects.
- *
IMAGO
- The perfect (generally winged) reproductive state of
an insect.
- *
INDIGENS
- The aboriginal animal or vegetable inhabitants of a
country or region.
- *
INFLORESCENCE
- The mode of arrangement of the flowers of plants.
- *
INFUSORIA
- A class of microscopic Animalcules, so called from
their having originally been observed in infusions of
vegetable matters. They consist of a gelatinous material
enclosed in a delicate membrane, the whole or part of
which is furnished with short vibrating hairs (called
cilia), by means of which the animalcules swim through
the water or convey the minute particles of their food
to the orifice of the mouth.
- *
INSECTIVOROUS
- Feeding on Insects.
- *
INVERTEBRATA,
or INVERTEBRATE ANIMALS
- Those animals which do not possess a backbone or spinal
column.
- *
LACUNÆ
- Spaces left among the tissues in some of the lower
animals, and serving in place of vessels for the circulation
of the fluids of the body.
- *
LAMELLATED
- Furnished with lamellæ or little plates.
- *
LARVA (pl
- LARVÆ). The first condition of an insect at its
issuing from the egg, when it is usually in the form of
a grub, caterpillar, or maggot.
- *
LARYNX
- The upper part of the windpipe opening into the gullet.
- *
LAURENTIAN
- A group of greatly altered and very ancient rocks,
which is greatly developed along the course of the St.
Laurence, whence the name. It is in these that the earliest
known traces of organic bodies have been found.
- *
LEGUMINOSÆ
- An order of plants represented by the common Peas and
Beans, having an irregular flower in which one petal stands
up like a wing, and the stamens and pistil are enclosed
in a sheath formed by two other petals. The fruit is a
pod (or legume).
- *
LEMURIDÆ
- A group of four-handed animals, distinct from the Monkeys
and approaching the Insectivorous Quadrupeds in some of
their characters and habits. Its members have the nostrils
curved or twisted, and a claw instead of a nail upon the
first finger of the hind hands.
- *
LEPIDOPTERA
- An order of Insects, characterised by the possession
of a spiral proboscis, and of four large more or less
scaly wings. It includes the well-known Butterflies and
Moths.
- *
LITTORAL
- Inhabiting the seashore.
- *
LOESS
- A marly deposit of recent (Post-Tertiary) date, which
occupies a great part of the valley of the Rhine.
- *
MALACOSTRACA
- The higher division of the Crustacea, including the
ordinary Crabs, Lobsters, Shrimps, &c., together with
the Woodlice and Sand-hoppers.
- *
MAMMALIA
- The highest class of animals, including the ordinary
hairy quadrupeds, the Whales, and Man, and characterised
by the production of living young which are nourished
after birth by milk from the teats (Mammoe, Mammary
glands) of the mother. A striking difference in embryonic
development has led to the division of this class into
two great groups; in one of these, when the embryo has
attained a certain stage, a vascular connection, called
the placenta, is formed between the embryo and
the mother; in the other this is wanting, and the young
are produced in a very incomplete state. The former, including
the greater part of the class, are called Placental
mammals; the latter, or Aplacental mammals,
include the Marsupials and Monotremes (Ornithorhynchus).
- *
MAMMIFEROUS
- Having mammæ; or teats (See MAMMALIA).
- *
MANDIBLES, in Insects
- The first or uppermost pair of jaws, which are generally
solid, horny, biting organs. In Birds the term is applied
to both jaws with their horny coverings. In Quadrupeds
the mandible is properly the lower jaw.
- *
MARSUPIALS
- An order of Mammalia in which the young are born in
a very incomplete state of development, and carried by
the mother, while sucking, in a ventral pouch (marsupium),
such as the Kangaroos, Opossums, &c. (see MAMMALIA).
- *
MAXILLÆ, in
Insects
- The second or lower pair of jaws, which are composed
of several joints and furnished with peculiar jointed
appendages called palpi, or feelers.
- *
MELANISM
- The opposite of albinism; an undue development of colouring
material in the skin and its appendages.
- *
METAMORPHIC ROCKS
- Sedimentary rocks which have undergone alteration,
generally by the action of heat, subsequently to their
deposition and consolidation.
- *
MOLLUSCA
- One of the great divisions of the Animal Kingdom, including
those animals which have a soft body, usually furnished
with a shell, and in which the nervous ganglia, or centres,
present no definite general arrangement. They are generally
known under the denomination of `shell-fish;' the cuttle-fish,
and the common snails, whelks, oysters, mussels, and cockles,
may serve as examples of them.
- *
MONOCOTYLEDONS,
or MONOCOTYLEDONOUS PLANTS
- Plants in which the seed sends up only a single seed-leaf
(or cotyledon); characterised by the absence of consecutive
layers of wood in the stem (endogenous growth), by the
veins of the leaves being generally straight, and by the
parts of the flowers being generally in multiples of three.
(Examples, Grasses, Lilies, Orchids, Palms, &c.)
- *
MORAINES
- The accumulations of fragments of rock brought down
by glaciers.
- *
MORPHOLOGY
- The law of form or structure independent of function.
- *
MYSIS-STAGE
- A stage in the development of certain Crustaceans (Prawns),
in which they closely resemble the adults of a genus (Mysis)
belonging to a slightly lower group.
- *
NASCENT
- Commencing development.
- *
NATATORY
- Adapted for the purpose of swimming.
- *
NAUPLIUS-FORM
- The earliest stage in the development of many Crustacea,
especially belonging to the lower groups. In this stage
the animal has a short body, with indistinct indications
of a division into segments, and three pairs of fringed
limbs. This form of the common fresh-water Cyclops
was described as a distinct genus under the name of Nauplius.
- *
NEURATION
- The arrangement of the veins or nervures in the wings
of Insects.
- *
NEUTERS
- Imperfectly developed females of certain social insects
(such as Ants and Bees), which perform all the labours
of the community. Hence they are also called workers.
- *
NICTITATING MEMBRANE
- A semi-transparent membrane, which can be drawn across
the eye in Birds and Reptiles, either to moderate the
effects of a strong light or to sweep particles of dust,
&c., from the surface of the eye.
- *
OCELLI
- The simple eyes or stemmata of Insects, usually situated
on the crown of the head between the great compound eyes.
- *
OESOPHAGUS
- The gullet.
- *
OOLITIC
- A great series of secondary rocks, so called from the
texture of some of its members, which appear to be made
up of a mass of small egg-like calcareous bodies.
- *
OPERCULUM
- A calcareous plate employed by many Mollusca to close
the aperture of their shell. The opercular valves
of Cirripedes are those which close the aperture of the
shell.
- *
ORBIT
- The bony cavity for the reception of the eye.
- *
ORGANISM
- An organised being, whether plant or animal.
- *
ORTHOSPERMOUS
- A term applied to those fruits of the Umbelliferæ
which have the seed straight.
- *
OSCULANT
- Forms or groups apparently intermediate between and
connecting other groups are said to be osculant.
- *
OVA
- Eggs.
- *
OVARIUM or OVARY
(in plants)
- The lower part of the pistil or female organ of the
flower, containing the ovules or incipient seeds; by growth
after the other organs of the flower have fallen, it usually
becomes converted into the fruit.
- *
OVIGEROUS
- Egg-bearing.
- *
OVULES (of plants)
- The seeds in the earliest condition.
- *
PACHYDERMS
- A group of Mammalia, so called from their thick skins,
and including the Elephant, Rhinoceros, Hippopotamus,
&c.
- *
PALÆOZOIC
- The oldest system of fossiliferous rocks.
- *
PALPI
- Jointed appendages to some of the organs of the mouth
in Insects and Crustacea.
- *
PAPILIONACEÆ
- An order of Plants (see LEGUMINOSÆ). The flowers
of these plants are called papilionaceous, or butterfly-like,
from the fancied resemblance of the expanded superior
petals to the wings of a butterfly.
- *
PARASITE
- An animal or plant living upon or in, and at the expense
of, another organism.
- *
PARTHENOGENESIS
- The production of living Organisms from unimpregnated
eggs or seeds.
- *
PEDUNCULATED
- Supported upon a stem or stalk. The pedunculated oak
has its acorns borne upon a footstalk.
- *
PELORIA or PELORISM
- The appearance of regularity of structure in the flowers
of plants which normally bear irregular flowers.
- *
PELVIS
- The bony arch to which the hind limbs of Vertebrate
animals are articulated.
- *
PETALS
- The leaves of the corolla, or second circle of organs
in a flower. They are usually of delicate texture and
brightly coloured.
- *
PHYLLODINEOUS
- Having flattened, leaf-like twigs or leafstalks instead
of true leaves.
- *
PIGMENT
- The colouring material produced generally in the superficial
parts of animals. The cells secreting it are called pigment-cells.
- *
PINNATE
- Bearing leaflets on each side of a central stalk.
- *
PISTILS
- The 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,
PLACENTATA, or Placental Mammals
- See MAMMALIA.
- *
PLANTIGRADES
- Quadrupeds which walk upon the whole sole of the foot,
like the Bears.
- *
PLASTIC
- Readily capable of change.
- *
PLEISTOCENE PERIOD
- The latest portion of the Tertiary epoch.
- *
PLUMULE (in plants)
- The minute bud between the seed-leaves of newly-germinated
plants.
- *
PLUTONIC ROCKS
- Rocks supposed to have been produced by igneous action
in the depths of the earth.
- *
POLLEN
- The 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 PLANTS
- Plants in which some flowers are unisexual and others
hermaphrodite. The unisexual (male and female) flowers,
may be on the same or on different plants.
- *
POLYMORPHIC
- Presenting many forms.
- *
POLYZOARY
- The common structure for the Polyzoa, such as the well-known
Sea-mats.
- *
PREHENSILE
- Capable of grasping.
- *
PREPOTENT
- Having a superiority of power.
- *
PRIMARIES
- The feathers forming the tip of the wing of a bird,
and inserted upon that part which represents the hand
of man.
- *
PROCESSES
- Projecting portions of bones, usually for the attachment
of muscles, ligaments, &c.
- *
PROPOLIS
- A resinous material collected by the Hive-Bees from
the opening buds of various trees.
- *
PROTEAN
- Exceedingly variable.
- *
PROTOZOA
- The 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
- PUPÆ). 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.
- *
RADICLE
- The minute root of an embryo plant.
- *
RAMUS
- One half of the lower jaw in the Mammalia. The portion
which rises to articulate with the skull is called the
ascending ramus.
- *
RANGE
- The 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.
- *
RETINA
- The 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.
- *
RETROGRESSION
- Backward 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.
- *
RHIZOPODS
- A 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.
- *
RODENTS
- The 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.
- *
RUBUS
- The Bramble Genus.
- *
RUDIMENTARY
- Very imperfectly developed.
- *
RUMINANTS
- The 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.
- *
SACRAL
- Belonging to the sacrum, or the bone composed usually
of two or more united vertebræ to which the sides
of the pelvis in Vertebrate animals are attached.
- *
SARCODE
- The gelatinous material of which the bodies of the
lowest animals (Protozoa) are composed.
- *
SCUTELLÆ
- The horny plates with which the feet of birds are generally
more or less covered, especially in front.
- *
SEDIMENTARY FORMATIONS
- Rocks deposited as sediments from water.
- *
SEGMENTS
- The transverse rings of which the body of an articulate
animal or Annelid is composed.
- *
SEPALS
- The leaves or segments of the calyx, or outermost envelope
of an ordinary flower. They are usually green, but sometimes
brightly coloured.
- *
SERRATURES
- Teeth like those of a saw.
- *
SESSILE
- Not supported on a stem or footstalk.
- *
SILURIAN SYSTEM
- A Very ancient system of fossiliferous rocks belonging
to the earlier part of the Palæozoic series.
- *
SPECIALISATION
- The setting apart of a particular organ for the performance
of a particular function.
- *
SPINAL CHORD
- The central portion of the nervous system in the Vertebrata,
which descends from the brain through the arches of the
vertebræ, and gives off nearly all the nerves to
the various organs of the body.
- *
STAMENS
- The 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.
- *
STERNUM
- The breast-bone.
- *
STIGMA
- The apical portion of the pistil in flowering plants.
- *
STIPULES
- Small leafy organs placed at the base of the footstalks
of the leaves in many plants.
- *
STYLE
- The middle portion of the perfect pistil, which rises
like a column from the ovary and supports the stigma at
its summit.
- *
SUBCUTANEOUS
- Situated beneath the skin.
- *
SUCTORIAL
- Adapted for sucking.
- *
SUTURES (in the skull)
- The lines of junction of the bones of which the skull
is composed.
- *
TARSUS (pl
- TARSI). The jointed feet of articulate animals, such
as Insects.
- *
TELEOSTEAN FISHES
- Fishes of the kind familiar to us in the present day,
having the skeleton usually completely ossified and the
scales horny.
- *
TENTACULA or TENTACLES
- Delicate fleshy organs of prehension or touch possessed
by many of the lower animals.
- *
TERTIARY
- The latest geological epoch, immediately preceding
the establishment of the present order of things.
- *
TRACHEA
- The windpipe or passage for the admission of air to
the lungs.
- *
TRIDACTYLE
- Three-fingered, or composed of three movable parts
attached to a common base.
- *
TRILOBITES
- A peculiar group of extinct Crustaceans, somewhat resembling
the Woodlice in external form, and, like some of them,
capable of rolling themselves up into a ball. Their remains
are found only in the Palæozoic rocks, and most
abundantly in those of Silurian age.
- *
TRIMORPHIC
- Presenting three distinct forms.
- *
UMBELLIFERÆ
- An order of plants in which the flowers, which contain
five stamens and a pistil with two styles, are supported
upon footstalks which spring from the top of the flower
stem and spread out like the wires of an umbrella, so
as to bring all the flowers in the same head (umbel)
nearly to the same level. (Examples, Parsley and
Carrot).
- *
UNGULATA
- Hoofed quadrupeds.
- *
UNICELLULAR
- Consisting of a single cell.
- *
VASCULAR
- Containing blood-vessels
- *
VERMIFORM
- Like a worm.
- *
VERTEBRATA:
or VERTEBRATE ANIMALS
- The highest division of the animal kingdom, so called
from the presence in most cases of a backbone composed
of numerous joints or vertebroe, which constitutes
the centre of the skeleton and at the same time supports
and protects the central parts of the nervous system.
- *
WHORLS
- The circles or spiral lines in which the parts of plants
are arranged upon the axis of growth.
- *
WORKERS
- See neuters.
- *
ZOEA-STAGE
- The earliest stage in the development of many of the
higher Crustacea, so called from the name of Zoea
applied to these young animals when they were supposed
to constitute a peculiar genus.
- *
ZOOIDS
- In many of the lower animals (such as the Corals, Medusæ,
&c.) reproduction takes place in two ways, namely,
by means of eggs and by a process of budding with or without
separation from the parent of the product of the latter,
which is often very different from that of the egg. The
individuality of the species is represented by the whole
of the form produced between two sexual reproductions;
and these forms, which are apparently individual animals,
have been called zooids.
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