School In The Open.

Star (Christchurch), Issue 19108, 28 June 1930, Page 32 (Supplement)

School In The Open.

Studies in the Great Out-of-Doors.

(By

F. J. S. Cornes, 8.A., B.Sc.)

The ‘Star” has arranged with Mr J. J. S. Cornes, 8.A., B.Sc., to write a series of illustrated articles which will give teachers and others a fuller appreciation of the Great Out-of-Doors. They will deal with various aspects of plant and animal life v as well as with inanimate nature. Questions and material for identification will be welcomed

THE EDUCATION OF A SNAIL. It has been shown that a limpet on the seashore rocks (and your limpet is just a snail with flattened spire) returns to its particular corner after an excursion for food. The advantage of returning to a particular spot is plain in those cases where the ipargin of the limpet’s conical shell fits the surface of the rock with precision and thus enables the animal to retain sea water when the tide goes out. Among those with this “homing” tendency the disfrom which they can regain their scar is limited to.a few inches—though one retentive individual seemed to know its way home” from a distance of four inches after a fortnight. The probability is that the limpet builds up a topographical memory of the immediate surroundings of its own particular “scar”. It seems to be well established that a garden snail can find its way home from a distance of six yards. Of one that . habitually spent the day in a hole in a garden wall it is recorded that for months it continued utilising as a nocturnal ladder a piece of wood sloping upward from a bed of herbs. Perhaps it .followed its'own slime-trail. Darwin mentions in the “Descent of Man” the case of two Roman or Edible

about thirty-odd million cash from them. The humour of this is that it takes a kauri tree anything from SOO to 1000 years to mature.” It is curious that.these authoritative statements should have been disregarded so long, especially that from the Indian forester, coming, as it did, from one used t r quick-growing, tropical trees. Popular Beliefs. “Popular beliefs are proverbially hard to kill”-—Hutchins. One of my daughters said to me on my return from Wellington last week, “Did you say. dad. last week that kauri trees could be grown for profit?'* And I. said “Yes!” “Well,” she said, “there is a correspondent in the ‘Star’ holding you up to ridicule, and we were taught at school that kauris took over a thousand years to grow, and that some, of our kauri trees in the North Island must have been planted before Christ was born.” This drove me to reading up my statement of the previous week, because even politicians make mistakes i sometimes.

Snails, one sickly and the ether vigorous, which were placed in a garden illprovided from the snail's point of view. The vigorous one went over the wall and found abundance next door. After twenty-four hours’ absence it returned to its companion, and in a short time both went over the wall. This is the sort of observation one would like to see repeated with precautions, and yet it seems to indicate at least some memory of locality. One would like to know whether the first slime-trail may have counted for something in the return journey. Very interesting experiments have been made by Miss E. L. Thompson on an American water-snail (Physa gyrina) which glides about in ponds, suspended upside down to the surface film, with mouth and creeping sole upwards, as often in our own Limnaea. The method of research was suggested by the ingenious experiments on dogs devised by Pavlov, a famous Russian physiologist. A dog’s mouth waters at the sight or smell of food, and it is possible to measure the quantity and quality of the secretion. If a whistle is blown or some colour is displayed when the food is shown, the dbg registers the association so thoroughly that in the course of time the sound or coloi-ir serves of itself to evoke the mouthwatering. The shadow works like the substance. Miss Thompson found that when the snail’s mouth was touched by a little piece of lettuce or the like the creature made a number—about four usually—of rapid * mouth-movements. But whenever she presented the food she also pressed the snail’s foot with a cleai. glass rod. She thus accustomed her snails to the two touches at the same time, and she continued until they were “trained” to link the two things together. She then gave her snail-class a rest for forty-eight hours, after which she tried the touch on the foot alone, without offer of food. The dux of the class made the. proper munching movements for the first seven trials right a>-ay, and others also did well. Some made less than the usual number of moutli-move-menls. And after ninety-six hours none would give any answer at all. But an animal of humble rank had learnt a lesson—even a snail will learn, will learn a lesson in association, though it does not last long. Miss Thompson also tried whether the snails would learn the right way and the wrong way to the surf* :e. She

fastened a Y-shaped glass tube in the aquarium, with one arm rough and leading to a slight, electric shock, and with the other smooth and leading to the surface of the water where the snail gets fresh air. The roughness of the wrong tube was meant to be a “warning”. The air was pressed out of the snail’s breathing chamber, and the creature was then placed in the. base of the Y-shaped tube. It was, of course, of value to the snail to get its lung filled as soon as possible. This w-ould be obtained by creeping, up the smooth arm; the other arm meant failure aiid a mild punishment. But the snails showed, so far as this experiment was concerned, complete incapacity to profit by experience. As the trials continued the percentage of mistakes did not diminish. It seems, then, that snails can learn by some associations and not by others. It is highly probable that in the individual experience in natural conditions they learn to associate certain external signs with the palatability and unpalatability of various foods. If we are to understand even a little of the long inclined plane of animal behaviour we must be clear that forming a. simple association is a long way below the level of intelligence. If a bell is rung whenever, food is put into the cage where mice are kept, they will gradually, not rapidly, learn to come scampering whenever the bell is rung, even though there is no food. The force of the association is too strong for them. Everyone knows that the chickens will come running xvhen they hear the familiar call that thev have learnt to associate with a meal. But

a cat in a new home will learn in a few clays to hurry at the novel sound of a dinner-bell. Now in this case the learning is so rapid that we have good cause to suspect that intelligence plays, its part. Similarly, when a neighbour’s hen that had once previously entered my garden and caused me to fire the first stone, returns and slinks off as soon as it sees me coming, I need more than the assurance of a psychologist (who probably has never seen a hen run;) to convince me that “association” alone is the cause. Indeed, this attitude is but another aspect of that colossal human conceit which, having granted man alone powers of reasoning and a conscience, goes one better by presenting him with a “soul” and a right to immortality! The truth is, of course, that all the powers we have are also possessed in lower or higher measure by other animals, but since we cannot put ourselves in their shoes we cannot understand. Therefore we cannot judge. When your psychologist becomes a hen or a crayfish, his opinion on hen or crayfish mentality will be valuable. Meanwhile, .as soon as he becomes scientific he will cease to be ridiculous to the ordinary observer of animals. Nevertheless,- in typical .cases of asso-ciation-forming. such as Pavlov’s dog and Miss Thompson’s water-snail, where a stimulus which has no natural interest becomes clpsely linked by long repetition to a significant stimulus such as the sight or the touch of food, until even the insignificant stimulus pulls the trigger of effective action, we are prob--1 ably, concerned with a physiological and