INSTINCT (Lat. instinctus, impulse, from instingiorr, to impel, front in, in+ to prick; connected NI it 11 Until. Stigyan, AS. stingan, to push). The sum of inherited reflex acts, becoming habitual and arising front blended reflex and subconscious though involuntary nets, performed at birth or through life blindly, with out practice or previous experience, effort, train ing, or thought. Instincts in animals are di rectly connected with the quest for food or with reproduction, especially care for the young, as in egg laying and nesting.
An instinctive act is any habitual and heredi tary reflex action frequently repeated throughout the life, not only of the individual. but of the species, in response to an external stimulus, in part controlled by rudimentary consciousness, but without volition, and always performed with reference to the needs of the animal and the maintenance and preservation of the species.
'Flu- instincts of each species or genus of ani mals are correlated with or dependent upon their peculiar structure and degree of specialization.
Ilabits are in general outlined to the life of the individual. and may or may not be trans mitted; but instincts are accumulated reflexes becoming by repetition habits which arc mani fested and handed down for multitudes of genera t ions.
Instinct is of all stages of development, front (1) merely simple, reflex acts. ns those of proto znans, sponges, and polyps, to (2) the highly F pecialiwd and complicated acts of the ants hex ial wasps and bees, as \yell as birds and mam grow in complexity. and are con trolled or blended with or aveomparried by more purely conscious and intellectual manifestations as we rise higher and higher in the animal scale, and as the nervous and muscular systems become more and,inore specialized. The instincts of most birds and mammals, and mostly those of the do mestic animals, associated with and been taught man. exhibit the germs of intelli genee, and even :it times of mason, in its present restricted sense given it by .1Iorgan.
The elements or factors out of which instincts arise are: (1) Need; or the necessities of exist ence: (2) the stimulus of the physical agents of heat, light, etc., or the physiologieal stimuli of hunger or of the reproductive (3) re flex acts at first more or less experimental or ten tative: (4) the repetition and natural selection of such acts, until they beenme (5) habits; (6) the perpetuation of such nets by inheritance: (7) the reflex nets and habits becoming blended with rudimentary oonseiousness (associative memory), without willing.
Instinctive acts are not rarely variable; they are sometimes at hitilt ; they may be modified by change of ciremnstanees. or, through disuse or changed habits and structures, entirely lapse. Thus. in aquati• animals. such as the whales, etc., whielt have evidently descended from some unknown terrestrial ancestors. en tirely new instincts arose as the result of a changed environment. The instincts of young animals may be replaced by a new set. Examples are those of animals which pass through a meta morphosis, as in the case of the caterpillar and butterfly, in which there are two sets or classes of instincts; i.e. (1) those by which the larva is enabled to live, and (2) the reproductive and egg-laying instincts of the butterfly. Thus, the same individual is born with a crop of innate congenital instincts, sheds them with its larval skin, so to speak, and then with the new birth of the butterfly appears a series of automatic and reflex habits and instincts which have arisen in response to the origin of the new structures, such as wings, sense organs, reproductive glands, genital armature, and the elaborate spiral tomrue adapted for taking an entirely different kind of diet from that of the grossly feeding caterpillar.
Nothing more plainly proves that instincts are not directly implanted by the direct interposition of a supernatural power, as is still insisted on by Fabre and Wasmann, than that they are special in nate or natural propensities, "transcending the general intelligence or experience of the creature," and arising from and dependent on peculiarities of structure and habits. Instincts are 'innate' and 'natural' because they have arisen by a natu ral growth and have been acquired. The 'saga city' of the ant, of the wasp, and of the bee is very wonderful ; but still more so when we realize the fact that it has evolved in response to the needs of the complicated organism of which it is the natural psychical outcome.