ANIMAL BEHAVIOR.-When an animal of any sort receives a stimulus it responds by doing something. If a dog be kicked it either fixes its teeth in the person of the kicker or crouches and runs away. If the stimulus be the sight or odor of food, more especially if this external stimulus coexist with an internal stimulus arising from hunger, the dog responds by seeking the food. The sum total of all that animals do, from whatever stimulus makes up animal behavior. It is noteworthy that the behavior of animals, as of plants, differs from the behavior of lifeless things, of which we sometimes speak, in that it is directed toward a biologic end. It serves either to preserve the animal from harm, as in the case of the dog that is kicked, or it serves in some other way to insure the welfare of the animal or of the species to which it belongs. This statement holds good even of that form of animal behavior which we call play. It is characteristic of human behavior also that it meets a biological end. There is often a very close likeness between the behavior of man and the behavior of animals under similar circumstances. It is natural to associate like behavior with like states of consciousness, and to believe, when one sees animals engaged in helping one another or in making love to one another, that this visible behavior is accompanied by the same feelings of pity or of love that we are ourselves conscious of. This conception of animal behavior which finds its earliest expression in fable has recently been widely disseminated through the writings of popular animal biographers. In such writings it is assumed that the behavior of the animals concerned is accompanied by states of consciousness such as would be present in men similarly circumstanced. It is the purpose of this article to indicate how far this assumption is in accord with the more generally accepted conclusions of scientific men. We may most readily grasp the dif

ferent types of animal behavior by examining certain characteristic examples.

I. The behavior of unicellular animals; simple reactions. There is found abundantly in stagnant water a one-celled animal, just visible to the naked eye, called the slipper animalcule or Paramecium. It has somewhat the form of a slipper and is covered with whiplashlike cilia, by the lashing of which it moves. Certain of the cilia situated in an open groove on one side of the body, drive particles of floating food down a tubular continuation of the groove and against the mouth which is at the bottom of the type.

It has long been known that Paramecia gather into groups about masses of food and that under certain conditions they frequently gather into companies in situations where there is no food. It is also known that at intervals they unite in pairs (conjugate). From such behavior it has been concluded, notably by Binet, that such animals as Paramecium are able to distinguish suitable food from other similar substances unsuited for food, and that they gather in companies for social purposes. Binet speaks of such animals as endowed with memory and volition.

The recent researches of Professor H. S. Jennings of the University of Michigan, have shown that Paramecia which ordinarily feed on masses of bacteria, gather about any mass that has a surface texture similar to that of the bacterial food mass and remain quiet about such mass as long as about the food mass. Thus bits of cotton cloth or of filter paper are not distinguished by them from food masses.

When a Paramecium is stimulated by mechanical, thermal or chemical means it responds by a characteristic movement which consists in backing for a short distance, turning to one side through a small angle and then moving ahead. It turns always to the same side, that opposite to the groove. The movement is like that of a locomotive when backed down a main track

and then run forward on a spur track or Y. If the Paramecium runs into a foreign body, it backs, turns, and then goes ahead; if it again strikes the foreign body the reaction is repeated and this repetition takes place at each renewed contact with the foreign body until finally in its forward movement the Paramecium clears the obstacle. The reaction is not called forth when the animal enters a portion of the water containing acid but is called forth when it leaves such a portion of water. If a drop of water containing carbonic acid gas be placed in the midst of the water containing Paramecia, a Paramecium moving about at random presently enters the drop. When, having crossed the drop, it reaches its further boundary and attempts to leave it, the characteristic reaction is given upon contact with the non-acidulated water and the animal backs and turns to one side. At each contact with the surface of the drop this reaction is repeated, so that the animal remains trapped in the drop, until by diffusion of its contained acid the drop becomes indistinguishable from the surrounding water. Other Paramecia soon enter, so that after a time the drop is crowded as full of them as it can hold. They are there, not by choice but because, having once entered, owing to their characteristic reaction they cannot get out.

Paramecia, like other animals produce carbonic acid gas which becomes dissolved in the water about them. If a single Paramecium remains quiet for a time the water immediately about it comes to contain the gas. Other Paramecia entering this water are unable to escape and so there is formed an accumulation such as was observed by Binet and attributed to social instinct. It is then quite unnecessary to assume any emotional or intellectual element in the behavior of Paramecium. There are many other cases of animal and plant behavior which are capable of similar explanation as reactions.

It may be laid down as a general principle everywhere recognized by students of animal behavior, that the assumption that a given behavior is intelligent or is rational is not warranted so long as there is evidence that the behavior may be explained in a simpler way; unless there is collateral evidence that the animal in question is intelligent or rational.

2. Instinctive behavior. If a chick which has been hatched in an incubator and has

never known mother hen or chick companions be placed, when a few hours old, on a surface upon which are scattered bits of food it presently begins pecking at one of the bits. At the first peck the chick is probably unsuccessful, but the effort is soon repeated with success. This first act of pecking we call instinctive. There are many similar acts. Young water birds, and chicks as well, swim when first placed in water. Young birds of many kinds, when first brought into contact with water under suitable conditions, go through elaborate bath and toilet movements.

Very complicated cases are found among insects. The caterpillar of the Yucca moth feeds on the Yucca plant. The moths leave the crysalis when the plant is in bloom and at once pair. The female then flies directly to a Yucca flower where she collects a wad of pollen. With this she flies to another flower, lays her eggs in the ovary of this flower and then, climbing to the stigma, stuffs the pollen into its hollow upper end. The flowers of the Yucca plant are thus insured of fertilization and the young larvæ of the Yucca moth are insured of food. The ovaries of the plant contain enough ovules to supply the larvæ of the moth and leave some still to develop into mature seeds. Behavior of this sort which consists of groups of co-ordinated acts, performed by an animal without previous experience and for the good of the individual or of the species are commonly spoken of as instinctive. All animals begin life with a certain equipment of instinctive behavior. In many animals the behavior remains throughout life largely or wholly instinctive, but in other cases it becomes

3. Intelligent behavior. If the young chick, after having eaten of palatable food be offered an unpalatable yellow and black cinnabar caterpillar, it seizes it but at once drops it and then wipes its bill on the ground as if displeased. After a few trials it consistently refuses such caterpillars. There is thus set up in the consciousness of the chick an association between the color of the distasteful caterpillar and its taste and the result is to check the tendency of the chick to peck at cinnabar caterpillars or other objects of similar color. The inborn instinct of the animal to peck at small objects has thus been modified by experience. We speak of those animals whose behavior thus shows evidence of modification by experience as intelligent. Some ani

mals make very slight additions to the stock of instinctive behavior with which they are born, while in others this initial stock of instinctive behavior is so largely modified by experience as to be scarcely recognizable.

The degree of intelligence may be measured by the rapidity with which an animal modifies its previous behavior to meet changed conditions.

Dr. Thorndike has recently performed the following experiments to test the intelligence of cats: The cats, when very hungry, were confined in slat cages provided with doors so .arranged as to fall open when a cord was pulled or a platform tread upon. In some cages it was necessary for the cat to do two or three such things in order to cause the door to fall open. Food for the cats was placed outside the door. Cats were placed repeatedly in such cages. and the time was noted which was required by each to release herself on each successive trial. The cat begins in each case by making random movements of clawing and biting at the bars of the cage. In the course of these movements she accidentally strikes the mechanism which releases the door, the door falls open and the cat secures the food. On the second trial the cat behaves in the same way, but the time required to effect her release is shorter, and on subsequent trials the time gradually diminishes to a minimum at which it remains constant. Thus in twenty-four trials with the same kitten she released herself on the first trial in one hundred and sixty seconds, on the second trial in twenty-eight seconds, and on the seventeenth trial in eight seconds, while in subsequent trials the time remained nearly as in the seventeenth trial.

Dr. Thorndike has learned that fish learn to pass through a tortuous passageway more rapidly on successive trials. It has been found also that rats confined in labyrinths of wire netting escape in diminished time at successive trials.

It is to be noted that in these cases the animal arrives at the solution of the problem by trial and failure until the right solution is finally found by chance. This solution once found, is recalled to the animal's consciousness when he is again presented with the same situation, and is recalled the more quickly at each successive trial.

Intelligent behavior is thus in sharp contrast to

4. Rational Behavior. A rational being

such as a man does not attempt to solve a problem by chance trials continued until he hits on the right way. A man enclosed in a box such as that used by Professor Thorndike would make some plan for effecting his escape, would have some reason for the plan. If the plan failed he would seek the cause of the failure, and if success came by chance the reason for such success.

The difference between intelligent and rational behavior is shown by experiments performed by Professor Lloyd Morgan with his dog. The dog was required to fetch a stick and on his return with it must pass between the upright bars of an iron fence. He seized the stick by the middle and on reaching the fence was stopped by its striking the bars. He struggled to pull the stick through by main force, but failed. It was only at the second attempt that, by a chance turn of the head he succeeded in getting the stick through. The results were similar on a second and third trial and on many subsequent trials. It was only after long training that the dog could be taught to drop the stick and get it through the fence endwise. Here the dog evidently learned by trial and failure. A rational animal would at once have compared the space between the bars with the length of the stick and would have had in advance a plan for meeting the difficulty.

Recent experiments of Professor Thorndike on monkeys show that their behavior also is intelligent and not rational. They improve by trial and failure. They differ from other animals merely in the fact that their reactions are more delicate and that they improve more rapidly.

We find then a progression from simple reactions, through those more complex groups of reactions which make up instinctive behavior to intelligent behavior characterized by experience-profit and through this to rational behavior. So far as is known no animal gets beyond the stage of intelligent behavior, to that of rational behavior, though every child passes in its. development from the one stage to the other.

The behavior of animals under certain circumstances has led to the belief that they were endowed with æsthetic and ethical feeling. The beautiful colors of certain male birds and the exquisite notes of others have been often cited as evidence of an æsthetic sense possessed by the mates of the birds which appear to be attracted by

these means. Here it can only be said that the facts lend themselves quite as well to the interpretation that the color and the sound serve merely as physiological stimuli to the female bird and that she is not necessarily conscious of any given song or plumage as more beautiful than any other. She is conscious of the effect only.

The question of the possession by animals of a sense of right and wrong can be but referred to. The sneaking behavior of a dog when detected lying on a forbidden couch suggests shame. Yet it is practically certain that in his previous experience detection in the act of lying on this couch has been associated in the dog's consciousness with physical discomfort at the hands of his master and that his sneaking behavior is due to a representation to his consciousness of this previous experience. This is sufficient to account for the facts and we are therefore estopped, on the fundamental principle already laid down, from assuming any higher form of conscious state on the part of the dog. Similarly when animals are supposed to exhibit joy as the result of a duty performed, investigation shows that the pleasure of the animal arises from an expectation of food or caresses, not necessarily from any other source. It is only when behavior rises to the rational ideational plane, as in man, that æsthetic and ethical elements are introduced. Animal behavior furnishes, however, all the elements out of which human behavior is evolved.

SOURCES: C. Lloyd Morgan: (1) "Animal Behavior," (2) "Animal Life and Intelligence," (3) "Instinct and habit," (4) "Introduction to Comparative Psychology. Romanes, (1) "Animal Intelligence," (2) "Mental Evolution." Wesley Mills: "The Nature and Development of Animal Intelligence." Sir John Lubbock: "The Senses of Animals," C. O. Whitman, "Animal Behavior in Wood's Holl Biological Lectures for 1898." H. S. Jennings, "The Psychology of a Protozoan," American Journal of Psychology, July, 1899. E. L. Thorndike, "Animal Intelligence," Psychological Review (Supplement), June, 1898. Binet: "The Psychic Life of Micro-organisms." JACOB REIGHARD,

Prof. of Zoology University of Michigan.

AUTOMOBILE, THE ELECTRIC.-Within the past few years new conditions have arisen which have brought about a revival

of interest in the automobile. The automobile was a commercial and an engineering success early in the century just closed, but opposition from the stage coach companies and the development of the steam railroad diverted attention from this branch of engineering. Sir Isaac Newton had suggested a steam automobile in 1680, a century before the invention of the steam engine as we know it now. He proposed to utilize the repulsion between the air and a jet of steam driven backward from a boiler carried on the vehicle. The invention of the steam engine by James Watt about a century later gave occasion for serious work in automobile development, and many inventors were more or less successful in producing self-propelling steam carriages. As an example, Mr. Goldsworthy Gurney built a steam carriage in 1827 which ran successfully for some time, on one occasion making a run of 85 miles in 10 hours, including stops. Speeds of from 32 to 35 miles per hour were attained on the excellent English country roads.* These facts make it evident that it was due to external circumstances and not to the lack of a good motor that there was little activity in the automobile industry during the middle of the nineteenth century. The horse, steam, cable and electric railways satisfied, for a time, the demand for rapid transit which impelled the early automobile constructors to their best efforts. Recently the selfpropelled road vehicle has again come into fashion for business and pleasure purposes partly on account of the excellent city paving and the improving condition of country roads which are now the rule. The fact that the time is now ripe for this mode of transportation is evidenced by the rapidity of the spread of its use. The growth is stimulated by the competition among the various available motors. The steam engine, the gasoline motor and the electric motor struggle for supremacy in a field formerly monopolized by the steam engine.

The electric automobile is in the development stage at the present time largely because the storage battery, upon which its success depends primarily, is subject to rapid deterioration. The failure of the storage battery as a source of energy for electric railway cars has prejudiced many people against it for automobile use. This failure was partly due to the inherent defects of

*Thurston's "History of the Development of the Steam Engine."