typical of the entire racial groups from which these samples came. None of these studies is an investigation of the whole population of Portugal, South Italy, Spain or Mexico. They are surveys of these stocks as actually found in the usual immigrant settlements in this county. However, the writer stands firmly upon the ground that the evidence points to the fact that these samples are very typical of the immigrants who reach this country from these European sources. Is not this after all the significant thing? For instance 85 per cent. of the total immigration from Italy in the past 30 years has been from the same districts of South Italy from which the largest sample of the writer's own investigation and that of Mr. Dickson and Miss Thomson came. The indirect evidence is that Miss Murdoch's Italian subjects were also from South rather than North Italy. In fact it is not impossible that the Italian in California is even a little superior on the average to his confrère who has neither energy nor ambition to get out of the industrial centers where most of these people first settle in our country. Of the Portuguese the writer can only venture a guess that he is much like the Portuguese found elsewhere in the United States, principally in New England. The Spanish-Mexican groups appear typical of the immigrants of this stock.

Does not the evidence accumulating, one phase of which has been reviewed here, point conclusively to the fact that a continued deluge of this country of the weaker stocks of Europe will ultimately affect the average intelligence of the population of this country? It is comment everywhere that the better stocks are losing ground compared with the poorer in the matter of offspring. The more intelligent classes are practicing, in one way or another, a conscious control of the number of their children. The result of this must mean a shifting in the average intelligence of the population toward that of the poorer stocks. Now hybridization of stocks is already taking place. It does not seem to be true that the inferior stocks always mix with their own kind-the history of the Kallikaks and such like proves that these stocks are constantly sending out their tenacles into the higher biological strains. Have we not been caught in the myth of the Melting Pot and in a sort of pious wish that all was well and that nothing could happen to us? The general economic progress of the past fifty years may have made us myopic of the larger meaning of these accompanying changes in our population. As Irving Fisher put it :21

Mechanical inventions . . . have given us more and more room for expansion and we have mistaken this progressive conquest of nature for a progressive improvement in ourselves.

21 Fisher, I.: "Impending Problems of Eugenics." THE SCIENTIFIC MONTHLY, 13: 215.

Certain sentimentalists have talked glibly of assimilation of racial stocks. This presupposes the capacity of one stock completely to take over another and make as the original stock was. There may be cultural assimilation (even this is doubtful in a technical sense), but there can not be biological assimilation. What we have is amalgamation, and as Conklin and others have pointed out, amalgamation means a hybrid stock, a stock compounded out of the elements of the two or more strains running into the new generation.

It is true that biologically the mixing of the North and South European is hardly analogous to the mixing say of the white and the black races or the whites and the mongoloids. Biologically as previously noted the European stocks are actually sub-races. Furthermore in reference at least to the latter stocks the problem is not an all or none principle. If these tests of general intelligence are at all significant it is evident at once that there is considerable overlapping in the various groups. For the future of this country a careful selection of the best in all the European stocks might be thought desirable. However, it is a common assumption of breeders and eugenists that for the production of a stable, homogeneous, strong stock isolation, group inbreeding and some occasional, but not too great, influx of exotic strains is necessary.23 The incoming of even somewhat distinct racial stocks might be profitable if of a high average intelligence and wide variability.

What we want, then, in brief is such a selection of European peoples that they will add variety to our population but not lower its intelligence. We have, of course, the comparable problem of preventing the continuance of inferior lines in the present population in this country without adding any more congenital liabilities to our people.

In conclusion the writer wishes to submit a few comments upon the practical phases of immigration problems which he believes grow out of these partial but significant investigations of mentality in immigrant stocks.

(1.) There must be a change in public opinion as to the desirability of large numbers of immigrants. We acquired the habit previous to 1914 of pointing proudly each year to the rising influx of foreigners into our land. The economic exploitation of cheap, unintelligent labor from abroad has fastened a serious racial as well as social-economic problem upon us. It has resulted in considerable ethnic displacement. The "Older Immigration" has con

22 Supra, p. 2-ref. Retzius, etc.

23 Cf. East and Jones, Inbreeding and Outbreeding, p. 264.

stantly lost ground in the face of the "New." The public opinion of this country needs arousing to opposition to the policy of economic stimulation of immigration to this country for the profits of the few at the expense of the general well-being.

(2.) This means that immigration should be controlled in the interests of the national welfare. The present law is inadequate, unjust and ill-administered. To base the percentages of admission on the number of immigrants of various nationalities in this country in 1910 is merely to continue relatively the same evils as heretofore. At present there seems to be some evidence that desirable people from Northern Europe and certain English colonies are being kept out while the ratio for Italians and Southern and Southeastern Europeans is large because of the "high" tides of immigration which they reached previously. Moreover, a literacy test is not an adequate criterion of the kind of persons we want. Due to inequality of educational opportunities in Europe, it is likely that persons of good intelligence may be barred because they can not read or write while persons really subnormal, but possessed of a modicum of education are able to pass the meagre demands on their reading and writing abilities at the gates of the country. Davenport has suggested a study of family strains in Europe, but this is expensive and impractical of execution.

The writer believes a set of well-worked out physical and psychological tests applied to all applicants for entrance into this country would assist in rejecting those whom we do not want. While the psychological tests are not perfect, they are far superior to any other scientific means which are available. The remarkable success of mental testing in our military organization during the war should dispel serious doubts as to the practical value of psychological tests for determining intelligence rankings and from that predicting success at tasks such as modern complex society demands. It would well repay our government to spend a considerable sum if necessary (say half the cost of one battleship) to devise under expert advice a set of tests to fit the needs of the immigration bureau. With adequate time at their disposal a body of experts could arrange a battery of tests, with norms, superior to anything yet at hand. Tests could be devised which would take into account the different linguistic and cultural backgrounds of the applicants, and further the non-verbal test offers possibility of expansion that is still unknown. On the basis of such tests, legal enactment could determine the standards to be set. In addition, if necessary, some differential standards on absolute numbers admissible any year could be laid down. It seems to me that there is not a better piece of service for the National Research Council than

Vol. XV.-28.

an attack upon this problem with an effort to secure the national government's support and adoption.

True, there remains after such a program, if it is ever accepted, the entire matter, noted already, of the inferior strains in the population now present in our country. Were we to set out on a sensible program regarding the immigrant, we should be led ultimately into another analogous one concerning the inferior stocks already extant in our population. Linking up these two programs with a sane educational policy we might look forward to a true national greatness. For who doubts that the contributors to a high culture must be a high-minded race?

On the other hand, if we continue our present muddling, irrational, hit-and-miss method of dealing with these two related problems and the country becomes more and more inundated with inferior stocks, the questions of American citizenship, education and cultural progress will be increasingly difficult of solution. In fact, ultimately such problems as we now see them will be submerged in the low standards of life and culture which arise out of a lessened average intelligence in the general population.

The picture may be pessimistic. It should arouse us to action. To those who are pragmatists and meliorists the matter is not hopeless, except in so far as the individuals and communities involved fail to recognize the gravity of the matter and naïvely close their eyes to the realities. Blind leaders of the blind, we may well shake our heads in serious meditation. But if the public consciousness of the country, under good leadership, realizes the problem soon enough there is no reason why we should not successfully solve this issue and assure our country's place of leadership in the world.

IN

CONCEPTUAL THINKING1

UNIVERSITY OF PITTSBURGH

By Dr. WALTER LIBBY

N the recent newspaper controversy concerning evolution, one of Mr. Bryan's supporters displayed some impatience at the emphasis placed by scientists on resemblances. He protested in the name of logic against what seemed to him an undue insistence on resemblance, resemblance, resemblance! But unless we take account of the similarity among phenomena, how are we to arrange and classify the data of physics, chemistry, botany and zoology, or arrive at the concepts of which the propositions and syllogisms of the logician are composed? We can have no science of distinct existences ununited by the bond of likeness. It is only by virtue of resemblances that we are enabled to pass from the observation of particulars to the consideration of universals. Bain and other psychologists are so far from belittling the ability to discover the bond of similarity among phenomena, often apparently unlike, that they regard it as characteristic of the man of genius. For James, genius is the possession of similar association to an extreme degree. To the type of genius that notices the identity underlying cognate thoughts belong the men of science, and it is in the concept that the conscious identification takes place.

Conception, or the cognition of the universal aspects of phenomena, can be illustrated from the history of the biological sciences. For example, what Linnaeus called the "System of Nature" was in reality a system of concepts. His classification of plants, though it prepared the way for more natural classifications, was crude, because based on superficial similarities. He, as Harvey-Gibson says, "elaborated a complex and beautifully arranged and catalogued set of pigeon-holes and forced the facts that Nature presented to him into these pigeon-holes, whether they fitted the receptacles or not." His zoological concepts were likewise inadequate. Suffice it to recall his vague use of the terms. Insecta, Vermes and Chaos. The likenesses revealed in animal structure by the comparative anatomists from Hunter to Cuvier and Owen led to a sharper definition of concepts and a more satisfactory classification. Paleontology afforded new materials for

1 The second lecture in a series entitled "The Psychology and Logic of Research" given before the Industrial Fellows of the Mellon Institute, February 14 to May 2, 1922.