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ANIMAL CHEMISTRY. ANIMAL CHEM'ISTRY'. See.

ANIMAL COL'ORS. The chief animal colors now in use are cochineal, kermes, and lac fye (qq.v.). See also.

AN'IMAL'CULE (Dimin. of Lat. animal, living; being). A popular name originally applied to any small animal, but later restricted to microscopic organisms, particularly such as are found in water. The term has no scientific standing, and is now little used except in compound names, such as bell-animalcule, wheel-animalcule, bear-animalcule, very different sorts of animals elsewhere described.

ANIMAL FLOWER. A sea-anemone or similar polyp, whose expanded colored tentacles resemble the petals of a blossom. For illustration, see.

ANIMAL HEAT. Heat generated in animal bodies by certain of the changes constantly taking place within them. A certain amount of heat is necessary to the proper performance of the functions of the body, and any material increase or decrease of it from the standard endangers health. The air and other objects surrounding the body being in almost all cases colder than it, are constantly stealing part of its warmth; but within the system there are processes constantly going on which produce more heat. When the heat thus generated is not dissipated fast enough, so that the body tends to become warmer than the due degree, perspiration results, the evapora- tion of which carries off the excess. The power of producing heat is in relation to the climate in which the animal is accustomed to live. It is weaker in warm climates than in cold, and consequently when an animal is removed from a warm to a cold climate it frequently pines and dies. In most fish and reptiles, commonly termed "cold-blooded animals," the temperature differs but little from that of the water or air in which they live: the same is the case with hiber- nating animals during the later part of their torpid condition. It may thus occur that the degree of temperature of "cold-blooded" animals may be higher than that of man.

Man has the power, to a greater degree than other warm-blooded animals, of adapting himself to changes of surrounding temperature. His average standard of heat is about 98.6° F. (36.8° C), varying with circumstances, being slightly higher after exercise or a hearty meal, and at noonday than at midnight. It differs slightly in various parts of the body, the interior being from ½° F. to 1½° F. higher than the exterior. It also varies in diseased conditions of the body, rising to 106° F., or even 111° F. to 113° F., in a fever or sunstroke or heatstroke, and falling as low as 90° F. in cholera. A temperature of 108° F., if maintained for several hours, is almost inevitably fatal. But if the body be in a healthy condition, the standard of heat is maintained, even when the person is exposed to intense heat, as in the case of men attending furnaces; one can for a short time be exposed to 350° F. of dry heat without materially raising the temperature of his own body, although he will lose weight by the copious perspiration induced.

Throughout the animal kingdom the power of generating heat bears a close relation to the activity or sluggishness of the animal. Thus, many birds which are perpetually in action have the highest temperature (100° F. to 112° F.); and the swallow and quick-flighted birds higher than the fowls which keep to the ground. The higher the standard of animal heat, the less able is the animal to bear a reduction of its temperature; if that of a bird or mammal be reduced 30° F. the vital changes become slower, more languid, and death ensues. Fish and frogs, on the other hand, may be inclosed in ice and still survive.

The sources of animal heat in the living body are the chemical and physical changes continually taking place. The chemical changes are those occurring in respiration, digestion, nutrition, secretion, and muscular and nervous action. It has been shown experimentally that when those functions are performed there is an increase of temperature. It is probable that muscular action is the most important item in heat production. The ultimate sources of heat are (1) the energy locked up in the food consumed and (2) in the oxygen inhaled in respiration. The food, in the processes of digestion, is split up into its constituent parts; these are absorbed, and may become parts of the textures and fluids of the body for a time; and these textures, in the performance of their functions, disintegrate, become redissolved, and are then eliminated by various channels from the body; all of these processes generate heat.

ANIMAL MAG'NETISM. See.

ANIMAL PSYCHOL'OGY. That department of psychology (q.v.) which has for its subject matter the composition and functions of mind as it is found in animals below man. As regards its problem, one cannot question the propriety of the title; but as regards the methods which it employs, animal psychology has little in common with psychology proper. The special method of normal psychology is the method of introspection (q.v.). Modern psychology is a system of facts gleaned from the introspective reports of trained observers, working under the refinements of experimental conditions. In sharp contrast with this is the position of animal psychology; for an investigator of the animal mind has no source of first-hand evidence. Results can be obtained only by a series of inferences. The data at our disposal are simply certain movements executed by the animal. From these movements we must draw our conclusion that such and such mental processes are present or absent, using the objective as index or criterion of the subjective.

It is clear that, under such circumstances, even the most conscientious, observer is liable to error. And the most obvious fallacy is that of humanizing the animal, of reading our own mind into his actions, and so of endowing him with all the forms of mental experience that are familiar to ourselves. Wundt, commenting on this attitude, cites an instance from Romanes's Animal Intelligence. "I have noticed," writes an English clergyman, "in one of my formicaria, a subterranean cemetery where I have seen some ants burying their dead by placing earth above them. One ant was evidently much affected, and tried to exhume the bodies; but the united exertions of the fellow sextons were more than sufficient to neutralize the effort of the disconsolate mourner." "How much," asks Wundt, "is fact, and how much imagination? It is a fact that ants carry out of their nest, deposit near by,