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its constant revelation of fresh, unforgettable charm. Exquisite spots, of course, may be found on other English rivers, and some, like Symonds Yat on the Wye, are of world-renowned beauty; but the very consummation of such loveliness tends to make other parts of their streams disappointing. With the Thames there is a uniform level of charm and grace.

The changes which have taken place during the past half-century, in the physical surroundings of the Thames, have been equalled by those in the fashions of such as depend on it for their livelihood, their sports, or their less strenuous pleasures. In the early 'sixties of the last century, for instance, almost the only punts were those, solid and heavy, used by the watermen (Leslie, the painter, was one of the first to use a punt as a pleasure boat), while to-day punts made of light cedar and mahogany are among the most popular craft. In rowing boats sculls have almost universally superseded I oars, and the rare private steam launch has given way to a swarm of motor canoes and other boats, which rush up and down the stream and every day cause damage through the disturbance of the water and the erosion of the banks. The 'cedar skiff' so highly prized by Etonians who, sixty years ago, were privileged to own a 'lock up,' has long since gone; and regattas I which once were few and far between and more or less private local festivals, abound on nearly every reach from Oxford to Putney-objectives of the cup-hunter, to be chronicled in the daily press. Compared with many of the rivers of the continent the Thames is small; contrasted with those of the New World diminutive; but even this fact helps to make it attractive, for at a glance one may comprehend its beauties and manifold attributes. Therefore it is that in spite of what poets, from Gower, Taylor and Spenser to Denham, Pope and Mr Bridges, have sung in its praise; in spite of all that books have said of its historic interest; in spite of all that pictures have tried to reveal of its charm, the Thames has never been adequately perpetuated; and it remains a mystery to many, and, perhaps, not least so to those who know it and love it best.

E. BERESFORD CHANCELLOR.

Art. 9.-ANIMAL BEHAVIOUR.

1. Theoretical Biology. By J. von Uexküll. Kegan Paul, 1926.

2. Tierpsychologie. By Friedrich Hempelmann. Leipzig: Akademische Verlagogesellschaft, 1926.

3. The Mentality of Apes. By Wolfgang Köhler. Kegan Paul, 1925.

4. Animal Mind. By Frances Pitt. Allen and Unwin,

1927.

5. The Study of Living Things. By E.S.Russell. Methuen,

1924.

those

DURING recent years there have been numerous careful experiments on the behaviour of the higher apes, of Prof. Köhler on chimpanzees being outstanding. While there are remarkable limitations in the way of achievement, it seems clearly proved that the higher apes are more intelligent than has been hitherto believed. If we take intelligent behaviour to mean that there is a correlate of perceptual inference, a sort of picture-logic, putting two and two together, then chimpanzees, gorillas, and orangs are often intelligent. We would apply this term to such activities as the following: building a pile of four boxes in order to reach the banana dangling from the roof; joining a short length of bamboo rod on to the end of a long one, thus making a single stick sufficient to retrieve the fruit outside the cage; using the teeth to whittle down the end of a short stick so that it might fit into the hollow end of a long one; discovering the effectiveness of a lever and then proceeding to find other levers of various sizes, including the heavy trapeze-bar with which it was possible to prise asunder the vertical bars of the cage, thus allowing the orang to gratify his long-cherished desire to look round the corner at his neighbour in the next cage. Very instructive is a kind of argument by analogy: thus after Prof. Köhler's chimpanzees had been greatly delighted with the loan of a hand-mirror, they pro ceeded to discover looking-glasses for themselves, such as polished pieces of metal and even pools of rain-water, into which they would gaze intently. The analogical extension of the discovery seems to us to imply in some

degree a psychical process, and its importance is not greatly lessened by the fact that the chimpanzees were never able to rid themselves of the idea that there was another ape on the other side of the looking-glass. To catch him nodding they made untiring efforts.

To appreciate the psychological significance of these and similar achievements, let us contrast them with others. No one who has studied the terms would propose to find in the apes' behaviour any evidence of reason, as distinguished from intelligence. For reason is taken to imply conceptual, as distinguished from perceptual, inference. Reasoning may be effected at an intelligent level, but reason implies experimenting with general ideas or concepts. So far as we know, there is no carefully recorded instance of animal behaviour that demands for its adequate description that we should credit the creature with general ideas and a capacity for working or playing with them. Man is often intelligent and occasionally rational; animals are often reflex and instinctive, and occasionally intelligent.

Köhler remarks that while the chimpanzees made some clever hits, they often failed to take a step which a child would have thought of. Picture, for instance, the chimpanzee who followed others (not a very common procedure) in making a four-story erection of boxes in order to reach the hanging fruit. Unluckily she placed the fourth box with its open end up, so that when she climbed into it she was little nearer the desired banana than if there had been only three boxes. Not understanding the relations of things, and only dimly appreciative of a concrete 'If this, then that,' she was nonplussed. Unable to correct her mistake, or fatigued by unwonted mental exertion, she curled up in the topmost box and fell asleep.

When we ask why an animal with a fine brain is not cleverer, we should recall the biological commonplace that no creature is likely to show much more cleverness than the conditions of its life demand. The anthropoid apes are strong and secure; they are as intelligent as is required, just as is the case with a golden eagle. Till the higher values are more than adumbrated, increase of knowledge would be too apt to mean increase of sorrow. It would not be good for an animal to have

much imagination, unless indeed it is going to begin a new ascent of man.

But after we have granted that apes are as intelligent as they need to be, and that their brain is neither as large nor as finely differentiated and integrated as ours, the question rises: What are their particular handicaps? The answer is two-fold: (a) that they seem to have a relatively poor repertory of mental images; and (b) that they have no language. The first drawback is illustrated by the general result of experimentation that the apes are seldom able to solve a new problem unless the elements in the solution are within its visual range at the time. But a child might have a mental presentation of what would fill the gap, and might search for it in a widened environment. Not that any hard and fast line can be drawn, for there is the well-known case of Miss Cunningham's young gorilla who, after sulking little on being refused a seat on her lap, searched round the room for a newspaper, which he proceeded to spread as an apron over his teacher's dress.

The second handicap is the merely incipient character of ape language. Chimpanzees have many words, indicative of particular experiences, such as meals and danger, or of particular emotions, such as joy and resentment, but there is no expression of a judgment in even the tiniest sentence, and there is not, as is seen in parrots, any social imitation of particular sounds. But it is language that widens the folding doors of the mind that necessity and visualisation have opened.

Having admitted that the intelligence of apes is not reason, and that it is hampered by limitations almost as striking as its achievements, let us compare it with other forms of behaviour. First of all, it is plain that the results of training, though proving educability, are often much less intelligent than they seem. A good illustration is given by Prof. L. T. Hobhouse, who tells of the elephant that put pennies deftly into the slot of the biscuit-delivering machine, but rejected with impatience the halfpennies that would not work the mechanism. This looked on the face of it hugely intelligent, but it was the outcome of very laborious habituation, implying weeks of training during which the trunk was guided to the automatic machine, and

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other weeks during which an associative discrimination of pennies from halfpennies was built up. It would be very extreme to say that there was no appreciation of significance on the elephant's part, but most of the performance depended on enregistering a sequence of acts. An association was established between the feel of the penny and raising the trunk to the slot, between the feel of the halfpenny and throwing it back to the visitor, but this did not involve even a spice of judgment. As long as the elephant was sensorily acute enough to distinguish pennies and halfpennies with the tip of its trunk, and plastic enough to establish a novel and very artificial neuro-muscular linkage, there was no need for it to go further in this particular connexion. And we must be frank enough to admit that few of us know in any precise way how the disappearance of the penny is followed by the appearance of the biscuit, and why a halfpenny will not work.

When we turn from training that results in a routine performance to training which has its outcome in a variety of actions appropriately adjusted, we hear more clearly the note of intelligence. This is illustrated by the elephant's co-operation with the workmen in the forest, by the shunting horse at a railway station in the country, or best of all by the collie dog in its successful completion of a difficult piece of shepherding. In such cases where the animal mind has been raised to a higher power by working in responsible partnership with man, the most striking feature is the judgment shown in adjusting the response to the peculiarities of a particular situation. In the collie's case it seems that successful achievement depends not only on the individually variable educability and on the shepherd's skilful training, but on the instruction given to the prentice by the parent dog, some say by the mother especially.

Before a chimpanzee hit upon the device of piling one box on the top of another to reach the high-hung fruit it tried other methods, such as climbing, swinging violently on the hanging rope, and standing on the shoulders of another ape. As these all failed, it was driven to further experimentation. But all that was done was on the line of purposeful and deliberate experiment towards an end in view. Yet there are other

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