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are forms which have lived for long periods in association with man. The wild species among them know his habits; they do not fear him unnecessarily, understanding how to take advantage of the results of his labor, while evading the consequences of the hostility that their depredations cause; the domestic species benefit by his care and protection. They are vigorous and prolific creatures. The changes in the condition of the land brought about by clearing and cultivation make the environment more and more suitable for them as time goes on, but less adapted for the native forms. Moreover, among the new arrivals there are apt to be some that find their new home peculiarly well adapted to their needs, so that they increase to an extent that crowds other species practically out of existence by the mere effect of their numbers, and by their consuming the available food supply, even if they are otherwise harmless. This is especially

the case when domestic animals are allowed to run wild in such places. It was a common thing in the early days of navigation to stock uninhabited islands with cattle, goats, or hogs, so that ships visiting them for water could also get a supply of fresh meat, an item of no small importance when voyages were of indefinitely long duration and cold storage was as yet undreamt of. The literature of many of these islands is full of references to the deforestation and other damage that these animals caused.

Fifth, as the number of individuals in a species becomes reduced, inbreeding becomes unavoidable, and its wellknown weakening effect makes the long survival of the species impossible. If an animal is to be saved, protection must be given before its numbers become too small. Laysan Island, an outlying member of the Hawaiian group, possesses among other peculiar birds a species of duck, the Laysan

teal, found nowhere except on this one small island. Fisher, in 1902, reported this species as reduced to fewer than one hundred individuals. Bailey, in the April-May, 1919, number of NATURAL HISTORY, reports it as reduced to seven. Even if among these seven individuals there are members of both sexes that can breed, it is inevitable that the species will soon die out from the effects of inbreeding. It is inbreeding that is likely to make the permanent preservation of the heath hen impossible, unless it may be found practicable to introduce the necessary new blood by crossing with a few individuals of the prairie chicken of the western states. The two species are fortunately so closely allied that crosses in all proportions would probably be fertile, and any changes in plumage or other visible characters produced by the crossing would probably soon breed out. Such an experiment seems well worth trying, as it appears to offer the

only possibility of preserving the heath

hen.

Last, but by no means least, life in the more uniform and protected environment of islands, produces in course of time a lack of adaptability in the species to endure changes or to resist new enemies, and may result in the loss of certain powers and functions through their disuse. Some of the birds for instance, having only short distances to travel and few enemies to escape from, have more or less completely lost the power of flight. Such retrogressive changes are not physical only but also mental. Compare, for instance, with the clever resourcefulness of the crow and the red fox, which maintain themselves in thickly settled districts in spite of man's hostility, the stupid tameness of the dodo and Steller's sea cow described in contemporaneous accounts, or the senseless timidity of certain small native Hawaiian birds of which it is said, though probably not without some exaggera

ISLAND ANIMALS AND PLANTS

tion, that they are afraid even to cross a road cut through the forest, and remain always on the side where they happened to be when it was built.

We cannot expect that among the small population of remote islands. there will be many influential people with a taste for scientific or popular natural history, or with any appreciation of the unique character of the native plants and animals and a realization of the urgent need for their care and protection-although few communities are now without some persons with such interests. But if these peculiar island species are allowed to become extinct through neglect and indifference, it is not merely a matter of local concern; it is also a loss to science and to scientific men, and to all with an interest in zoology and botany, scientific or popular, throughout the world; a loss that cannot be repaired in the future and that will always be a reproach and a discredit to the present generation.

Our Government and our scientific societies should see to it that on our own island possessions at least the rare and disappearing species are given every care and protection, but the matter is such an urgent one and of such importance to science that the duty should not be considered as limited by political boundaries, and we should regard it as a proper ground for international cooperation, or for assisting those even in foreign possessions who need encouragement or help to enable them to carry on such protective work. Even if we regard science as such a

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lofty and transcendental conception as to be indifferent to the mere extinction and annihilation of the most interesting part of the material with which it deals, the information about the life, habits, food, and reproduction of these vanishing species that would be acquired in a serious effort to preserve them would add to our knowledge facts that must be studied now or never. Neglect of this plain duty and of this last and only opportunity will be a cause of regret in the future.

The whole subject of conservation is one that must receive greater consideration than that which has yet been conceded to it. We too often dismiss it from our minds, and silence our consciences with the thought that it can be dealt with by the Government or by other people who have not sufficient troubles of their own. That we ought to do as little damage to the world and to nature as we can during our brief stay here, and that we should leave for those who come after us some of the natural resources and as many as we can of the wonderful and interesting animals and plants and the other beautiful objects in nature which we enjoy, instead of turning the world over to them in the condition of a squeezed lemon, is a doctrine too seldom taught in our schools or colleges and too rarely preached in Our churches. But after it is too lateand that time is now not far aheadthere is likely to come a realization that the greatest mistake ever made by the human race was not to have taken that idea as the foundation of its code of ethics and conduct.

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MAJOR ROBERT M. YERKES

Lately Chief of the Division of Psychology, Medical Department, United States Army

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Line of draftees entering the psychological examining building for intelligence rating

The Army Intelligence Tests

By GEORGE F. ARPS

Professor of Psychology, the Ohio State University; lately Major, S. C., U. S. Army

W

WHEN the internecine struggle of 1914 drew this nation into the vortex the American Republic was confronted with an emergency of such proportion as appeared likely to require the services of every phase of modern science. That psychology, in many respects the most youthful of the applied sciences, was able to place at the disposal of the Government a technique whereby a fairly accurate mental measurement could be made of each raw, problematical recruit, is but a striking illustration of American resourcefulness, originality, and initiative. It is likewise an effective commentary on the relative merit of American versus German points of view in the problem of human behavior.

A workably accurate scientific classification of brain power of the manhood of the Army would not only enormously abbreviate the period of organization, but also make possible a wise expenditure of this power and thus prevent wastage of material resources as well as man power. It has been the writer's experience that commanding officers are everywhere and always eager to adopt any technique or method

which will enable them to discover native resourcefulness and utilize it in positions of leadership and responsibility. It is equally important to discover those so low in the scale of intelligence as to constitute a menace in the use of firearms and to the success of any military undertaking.

In recognition of these clearly desirable ends the Medical Department of the Army, in August, 1917, accepted for trial the details of the technique, methods, and procedure prepared by the Committee on the Psychological Examination of Recruits, whereby a mental classification of all recruits could be made shortly upon arrival in the various cantonments. The trial results led the Surgeon General of the Army to recommend to the War Department the extension of intelligence examining to "all company officers, all candidates for officers' training camps, and all drafted and enlisted men."

Early in 1918, the War Department approved the recommendation of the Surgeon General and created the Division of Psychology in the Sanitary Corps of the Medical Department for the purpose of carrying into effect the psychological service.

Group of literate draftees taking ALPHA intelligence test

Scoring ALPHA examination papers. By means of stencils it was possible to score the papers almost as rapidly as succeeding groups were examined. Commanding officers received the results within twenty-four hours after examination

Psychological Personnel

Upon the creation of the Division of Psychology in the Medical Department, about one hundred officers and three hundred enlisted men were mobilized at Camp Greenleaf, Georgia, in the Medical Officers Training Camp, and there given intensive military training, instruction in the technique and methods of psychological examining, army paper work, and such other instruction required of the regular regular medical officer.

The above personnel were then assigned to the various large cantonments to carry into effect the methods of psychological examining. From three to five commissioned officers and four to eight enlisted men were as

signed to each of the larger training camps. In addition, from twenty to sixty privates were assigned for temporary duty as scorers, clerks, typists, and orderlies, to assist in the conduct of the examinations and to

make readily available the results to the various commanding officers.

With this organization and by means of the group method, it was possible to examine, in times of pressure, as many as three thousand recruits in a single day in a given cantonment. Variety of Tests Employed

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ease.

ALPHA. This is a group test and is intended for literates who can read, write, and understand English with a fair degree of The general practice was to segregate recruits as they entered the examining station on the basis of the grade in school last attended-fifth grade, as a rule, for the white and eighth grade for the colored troops. Those who fell below these grades were ordered to take the illiterate (BETA) examination. With proper facilities as many as five hundred recruits could be examined in

approximately one hour. The procedure was entirely objective in that the examiner and the scorers were

wholly unacquainted with the men examined. The scoring was done by means of stencils and in the absence of the men examined, which procedure eliminated personal bias and prejudice.

Differences in intelligence, or degrees of mental competency, as revealed by the scores made, were indicated by

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