stance submitted for analysis may be readily detected by dissolving some of the substance in water and adding a solution of bleaching-powder: in the presence of aniline an intense purple col- oration is produced. Another test for aniline is afforded by the so-called carbylamine reaction : a drop of aniline added to a mixture of chloro- form and a solution of caustic potash in ordinary alcohol produces an intensely nauseous smell, due to the formation of phenyl-carbylaniine ( phenyl iso-cyanide) , CoHjXC. For bibliography, see Coal-Tar Colors.
ANILINE COL'ORS. See Co.i.-Tar Colors.
AN'IMAL ( Lat. a living being, from anima,
current of air, breath of life, soul, animus, soul,
mind; from the Skr. root an, to breathe). A
representative of one of the two great groups
of organisms, the other including plants. The
distinction betw-een animal and plant is hard to
draw sharply, although the usual differences be-
tween the higher representatives of the two
groups are obvious enough. Jlost higher ani-
mals difter from most higher plants in that their
food is ehiefl.v solid and organic, in their capacity
for locomotion, in their alimentary tube, muscles,
nervous system, and sense organs, in their lim-
ited growth and greater specialization of parts.
This list of differences is realh' less formidable
than it appears: it resolves itself chiefly into
a difference of food, which demands that the
animal shall seek the food and be provided with
organs for locomotion (muscles, nervous system,
and sense organs) and digestion. The difference
in general form of body is due to the different
methods of getting the (dissimilar) food. This
difference in food (solid and organic, as opposed
to fluid and inorganic) serves in a general way
to divide even the lower animals from the lower
plants. But most animal and plant parasites are
alike in requiring liquid, organic f-ood: even green
plants use organic food (some in large quantities;
see Sundew), and all animals require inorganic
food.
Locomotion is not a distinguishing characteristic of animals, first, because great groups of animals are permanently attached; namely, among protozoans, suctoria, sponges; among ccelenterates, most hydroids and corals; crinoids (sea-lilies) ; bryozoans, barnacles, and most ascidians. Single casesof attaehedauimalsare found in other groups. Sccondl,y, bacteria, diatoms. oscil- laria, certain unicellular green alg«, and many plant "swarm-spores" are more or less locomo- tive. In respect to irritabilit.v there is little fun- damental difference even between the higher ani- mals and plants, for plants respond to the same agents as do animals, but less perfectly. The reproductive process is fundamentally the same in the two kingdoms. In their chemical com- position the higher animals differ from most plants; for the former contain no cellulose, whereas the latter are largel.v built up of it. Hut cellulose is f(!und also among animals, especially in the test of the tunicates. In their cell-strne- turc and cell-physiology animals are almost in- distinguishable from plants. The fundamental living substance. Called protoplasm, is substan- tially alike in the two kingdoms, and»it is prob- able that future studies will make dimmer rather than clearer the line separating them. The |iriiicipal functions of animals are connect- ed with nutrition, locomotion, sensation and re- action, reproduction, and relation to other organ- isms. Nutrition involves first the acquisition of food. Food is ( 1 ) inorganic — water, oxygen, certain salts; or (2) organic — either vegetable or animal, either dead or living, passive or active. Attached animals depend mostly on dead or on passive living organisms, brought to them in cur- rents of water. Those which live on active ani- mals must have the most powerful organs of locomotion and sense. Solid food has to be trit- urated by teeth or crushing jaws, and digested in a food-canal. The fluids thus obtained pass through the wall of the food-canal either into the general body spaces or into blood vessels, which carry them to the tissues, where they are assimilated or burned for heat and energv. When the food is exclusively fluid, it ma}' soak through the body wall, as in tapeworms, which have no alimentary tract. The ox.vgen required passes through the wall of the body, is imbibed with water, or enters through special thin wall-tracts of the body surface known as gills or lungs. The body space or blood vessels carry the oxygen +o the tissues, where it is used in combustion and in building up the organic compounds. The waste products of catabolism in the tissues are cast into the body spaces (or blood vessels) and eliminated, either directly or bv special excretory organs. See Anatomy ; Alimentary System ; EESPiRATor.T System; Muscular System, and similar articles.
Locomotion involves locomotive apparatus of divers kinds, jets of water, suckers and contract- ile tubes, lashes, tails, cilia, paddles, fins, wings, and legs. It involves also muscles and a nervous system to control them.
All the protoplasm of the living body is irrita- ble, but parts of the surface are told off as areas of special sense; for contact, hearing, taste, smell, sight, and temperature. To receive these impres- sions and to set in action appropriate movements, the central nervous system has become special- ized. In the definite reactions which accompany particular situations to the world external to the animal lie the first evidences of a "psvchie life." All sessile animals are characterized by lack of many sense-organs, reduction of muscular and nervous systems, and reduction of instincts. Owing to accidents, the number of individuals tends constantly to diminish, yet it must be maintained. The single way that organisms have of making good losses or increasing their numbers is by dividing; this is the essence of reproduction (q.v.). Of especial significance is the fact that in all. groups of animals the bits which have been constricted off (gametes) from time to time unite in pairs to form zygotes before going on with their development. In all reproduction, the dividing individuals give rise to two incomplete individuals, except in the case where the division separates a '"germ cell" from the body that carried it. The divided pieces or the germ cells are imperfect representatives of the species: they must "regenerate" or "develop" to produce the adult condition. See Embryology; Reproduction.
The relations of animals to other organisms are varied. Many animals, especially in the higher groups, care for their young. Many protect themselves from their enemies by concealment or by fight; others are powerful for offense and defense. On account of the mating instincts, many higher animals have gained peculiar methods of appealing to the eye or ear or smell of other members of the species.
