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METHODS IN ANIMAL PSYCHOLOGY.

By LINUS W. KLINE, PH. D.

The differentiation of comparative psychology, as a branch and method to general psychology, has been comparatively slow. Its growth, however, has been natural and healthy, and its contributions to the study of mind are ever increasing in value. A complete historical account of this differentiation would be quite premature; yet it may be worth while to note in passing that several of the special problems of psychology,-for example: emotions, instinct, habit, heredity, etc., have been treated on very broad lines by such all-around scientists as La Marck, Brehm, Darwin, Kingsley, Wallace and Agassiz. A little later, men like Naegal, Huxley, Romaines, Lubbock, Graber, and Spalding, began to focus down and make experiments and observations on the senses, habits and intelligence of animals. Running somewhat parallel with these two groups of more purely scientific writers are the speculative and philosophic pens of Oken, Lewes, Spencer, Schneider, Weismann, Büchner, Cope and others who have evaluated and ennobled the facts of organic life by indicating their significance on the more serious and time-honored problems of mind and philosophy.

At present, definite problems, as the formation of association processess,1 imitation, habit and instinct, are put to animals by playing upon some one or more fundamental instincts and taxic motions like those of hunger, sex, discomfort in solitude and prison, preferences for certain colors, geotaxis, chemotaxis, tonotaxis, etc. The ablest representative for psychology in this work is Lloyd Morgan, whose careful and critical interpretations of the objective manifestations of mind through bodily activities have done much to make comparative psychology reputable as a science, and even now essential to a comprehensive understanding of the more fundamental problems of mind. Wundt likewise has criticised to great advantage the usual erroneous and loose interpretations of animal activities. Criticisms of this type should not cease yet awhile.

The matter of interpretation at this stage, however, it seems to me is secondary. The most urgent need at present is more and better methods to get at the facts, which, when once discovered, will receive ample and proper attention.

Thorndike, Edward L.: Animal Intelligence. An experimental study of the associative processes in animals. N. Y., June, 1898.

The systematic study of animals thus far has been conducted along two lines: oue, for a better name, we shall call the natural method. This consists in observing carefully and continuously the free life of an animal, for example: Huber, Moggridge, and McCook on ants, Audubon on birds, Figuier on insects, Mills' on our domestic animals; the second line of work may be termed the experimental method. Here the animal is subjected to certain conditions essential in putting a question, and that favor the performance of activities that shall contribute material for answering a problem.

Both methods are necessary to a more abundant ingathering of facts. Both are frequently used by the same investigators, e. g., Lubbock and Bethe' on ants, and Morgan on birds. Both have their share of errors and abuses. In the natural methods the cleverness of animals is sometimes overestimated, anecdotes of a questionable foundation are given too much credence. In the experimental method, conditions too artificial are liable to be created, thereby inhibiting the free expression of the animal's acts. Fear is too often present, dominating and modifying every A recent investigation makes exclusive use of the second method, which seems to me exposes the results to serious criticism. I shall revert to this investigation later in this paper.

act.

Partly as an illustration of the use of these two methods combined, partly to reinforce observations already made, and lastly to present a bit of new material, I present the results of experiments and observations made on vorticella, wasps, chicks and

rats.

VORTICELLA GRACILIS."

The object here was to discover what activities, if any, have a psychological significance or value. The activities may be subsumbed under the following rubrics: Self-preservation, reproduction, and "miscellaneous." The first includes all those movements, whatever, both of the whole and parts of the cell, exerted in food-getting, ejecting detritus, placing the mouth in a more advantageous position for receiving food, contracting the stalk to escape an enemy, or when cilia touch any large body, dead or alive, etc.

The reproductive activities need no specification. Miscellaneous activities include all those movements for which we can

Mills, Wesley: Animal Intelligence. 307 pp. The Macmillan Co., 1898. Bethe, Albrecht: Dür fur wirden Ameisen und Biemen psychische Qualitäten zuschreiben? Pflüger Archiv für Physiologie. Bd. LXX 1898. I am greatly indebted to Dr. C. F. Hodge for many valuable suggestions in carrying out this experiment.

assign no cause, e. g., violent contraction of the stalk at a time when the field is free from any disturbing element that might be revealed by the microscope, food abundant, and body fairly well filled. Probably a study directed with a view to ascertain its chemotaxic and tonotaxic reactions would make some of these activities meaningful. I turn to the activities of self-preservation and note first the movements of the body as a whole. If the long axis of stalk and calyx is in and with a current of water,1 the calyx is soon turned across the stream, forming an angle with the stalk. It is evident, owing to the well-known bell-shape of the calyx and the position of the cilia, that thus turning the bell would greatly facilitate food getting. Is there a psychical element in such a movement, i. e., is the movement the outcome of the exercise of a psychical force? It appears to me that an affirmative answer is open to two serious objections: First, it can be explained in several other equally as plausible terms. The reaction to hunger alone is sufficient to account for the movement, and when we reflect that the habitat of V. is on grasses bathed by currents, natural selection might well be invoked as the principle that has impressed a reflex or mechanical movement of this sort on the cell. Then again, the inequality of the density of the current on the sides of the bell is a stimulus sufficient to cause a reaction expressed in movement (tonotaxis). Reactions of this sort occur in paramacia, hydra, frog, and the human conjunctive; second, to ascribe a directing role to whatever psychoses that may be present in these forms to activities of this sort, precludes further investigation-just as the "fiat creation hypothesis" of the middle ages kept men from enquiring into the more rational ways of world growth.

The mouth cilia are so directed as to either receive or reject small particles of matter. These activities have been championed as psychical. That the cilia do these things there can be no question, but that they are movements directed by a psychosis, i. e., are really selective, expressing choice, is quite another question. Before this question can be scientifically discussed, it seems to me another question must first be determined, viz.: Have vorticellæ a choice in food-do they not

1A current of sterilized water carrying yeast cells from a large flask was kept flowing under the cover slip. The water was drawn from the flask through a glass syphon, down to a capillary point, placed at one end of the cover slip, and a filter-paper drip attached to the other end. The microscope used was a Zeiss, apochromatic series, comp' ocular 12 objective 16 mm., which gave a magnification 190 diameters, and sometimes ocular 6, objective 4 mm. was used-magnification 375 diameters. The vorticella were found in great abundance from flags placed in an aquarium three weeks.

Jennings, H. S.: Reaction of Ciliate Infusoria. Journal of Physiology, Vol. 21, 1897, pp. 258-321.

receive both digestible and indigestible material alike, and when filled eject both alike? It is a physical impossibility to receive even all the digestible material that comes their way. If given yeast they will receive 2, 3, or 4 grains at once and will then whirl the others away for 5, 10, sometimes 15 minutes before admitting any more. So that what has been interpreted as a selective process may be a reaction to "enough." To get facts that would answer the question one would have to first find a material' that they reject2 altogether, then mix it with a palatable food, say yeast grains, and note their reactions toward the mixture.

I present in Table I the notes from my diary on a typical experiment with vorticella. It presents nothing essentially new or different from the work of Drs. Hodge and Aiken, save that yeast is a food for all the V. that I observed.

Again, do they discern between enemies and friends, between what is harmful and unharmful? If they do, we should expect to see the stalk contract in the presence of certain objects and remain extended in others or even remain in contact with them; and if they do not, we should expect the stalk to contract when the calyx comes in contact with any rigid, resisting, unmanageable object, organic or inorganic, dead or living matter. The latter condition is just what we do find. Vorticella takes no risks, trusts nothing, as it were, but contracts the stalk whenever the sensitive parts of the calyx or cilia meet with any resisting body whatsoever. I have observed the stalk contract when yeast cells and other food material came floating by in unmanageable quantities, or when the peristomal region came in contact with a large colony of bacteria-if the colony is small, they are hurled away by the cilia. I counted 118 stalk contractions due to the calyx hitting a dead leaf fibre. How long it had been reacting to this particular object, and how much longer it would have continued, had no accident intervened, can only be conjectured.

It seems to me all that we can say here is that the sense of touch mediates bigness, and persistence or rigidity, and reactions to such stimuli imply nothing more than simple mechanical reflexes.

Under the category of reproductive activities it is sometimes urged that the attachment of the free-swimming zoid near the base of the calyx is an expression of choice of selection on the part of the zoid, and therefore psychic. The zoospores of the cryptogamic world do equally as clever things in selecting

This problem was suggested to me by Dr. Adolf Meyer. "The substance would have to be partly insoluble, at least in water, and of low specific gravity. I suggest pepsin, lycopodium powder, a few of the salts of calcium and barium, ground glass and the like.

the right oospore in which to penetrate. My fondness for mysticism and the "brand-new" is too feeble to urge me to invade the botanist's realm searching for psychological material.

The presence of a psychoses is not denied. There may be feelings corresponding to the stimuli bigness, rigidity or persistence, whenever the organism mechanically responds to such. All that I affirm is that these activities give no indication that they are the outcome of the exercise of a psychical principle.

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None.

None. Stalk well
extended.
Regularly.
Feeble.

4 x per min. Less frequent. None.

Remarks.

Cilia moving slowly.
about 3 per min.

Vesicle closing

Feeding occasionally. Takes in yeast grains.

Stopped feeding.

A swift current bearing yeast grains has just started up. The long axis of stalk and bell are in line with current.

Feeding again. Taken in two yeast grs.
Takes in yeast grs. occasionally, permits

the great majority to go by after being
twirled rapidly by the cilia. It is a phy-
sical impossibility to take in all the
yeast grains that come by, or, for that
matter, other food material. The food
revolves around a common center. The
diameter of each revolution of any one
revolving food mass grows shorter.
The food thus approaches the center,
but not quite, as it gradually works to-
ward the mouth when nearing com-
plete digestion.

Once, whenalarge Feeding slowly. Takes in 3 or 4 yeast grs. at once, then sets them to revolving with the great mass of food.

torulae struck the
body near the
mouth parts.

None.

None.

None.

None.

Has turned the bell almost at right
angles to the stream, (the stalk is in
line with the stream). This offers a
better position for taking food.
Two yeast grains, after making one
revolution, were hurled out not seri-
uosly injured.

Ejected yeast detritus, i. e., cells that
had been digested to a shapeless mass.
Followed two yeast grains through one
revolution; time, 4 min. and 45 sec.,
about.

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