orated, will mark an epoch in the study of heredity, being apparently the first successful attempt to deal experimentally with a particular factor or set of factors in the germplasm.

There remains another question we must try to answer before we close, namely, "What share has the mind taken in evolution?" From the point of view of the biologist, describing and generalizing on what he can observe, evolution may be represented as a series of metabolic changes in living matter molded by the environment. It will naturally be objected that such a description of life and its manifestations as a physico-chemical mechanism takes no account of mind. Surely, it will be said, mind must have affected the course of evolution, and may indeed be considered as the most important factor in the process. Now, without in the least wishing to deny the importance of the mind, I would maintain that there is no justification for the belief that it has acted or could act as something guiding or interfering with the course of metabolism. This is not the place to enter into a philosophical discussion on the ultimate nature of our experience and its contents, nor would I be competent to do so; nevertheless, a scientific explanation of evolution can not ignore the problem of mind if it is to satisfy the average man.

Let me put the matter as briefly as possible at the risk of seeming somewhat dogmatic. It will be admitted that all the manifestations of living organisms depend, as mentioned above, on series of physico-chemical changes continuing without break, each step determining that which follows; also that the socalled general laws of physics and of chemistry hold good in living processes. Since, so far as living processes are known and understood, they can be fully explained in accordance with these laws, there is no need and no justification for calling in the help of any special vital force or other directive influence to account for them. Such crude vitalistic theories are now discredited, but tend to return in a more subtle form as the doctrine

of the interaction of body and mind, of the influence of the mind on the activities of the body. But, try as we may, we can not conceive how a physical process can be interrupted or supplemented by non-physical agencies. Rather do we believe that to the continuous physico-chemical series of events there corresponds a continuous series of mental events inevitably connected with it; that the two series are but partial views or abstractions, two aspects of some more complete whole, the one seen from without, the other from within, the one observed, the other felt. One is capable of being described in scientific language as a consistent series of events in an outside world, the other is ascertained by introspection, and is describable as a series of mental events in psychical terms. There is no possibility of the one affecting or controlling the other, since they are not independent of each other. Indissolubly connected, any change in the one is necessarily accompanied by a corresponding change in the other. The mind is not a product of metabolism as materialism would imply, still less an epiphenomenon or meaningless by-product as some have held. I am well aware that the view just put forward is rejected by many philosophers, nevertheless it seems to me to be the best and indeed the only working hypothesis the biologist can use in the present state of knowledge. The student of biology, however, is not concerned with the building up of systems of philosophy, though he should realize that the mental series of events lies outside the sphere of natural science.

The question, then, which is the more important in evolution, the mental or the physical series, has no meaning, since one can not happen without the other. The two have evolved together pari passu. We know of no mind apart from body, and have no right to assume that metabolic processes can occur without corresponding mental processes, however simple they may be.

Simple response to stimulus is the basis of all behavior. Responses may be linked together in chains, each acting as a stimulus to

start the next; they can be modified by other simultaneous responses, or by the effects left behind by previous responses, and so may be built up into the most complicated behavior. But, owing to our very incomplete knowledge of the physical-chemical events concerned, we constantly, when describing the behavior of living organisms, pass, so to speak, from the physical to the mental series, filling up the gaps in our knowledge of the one from the other. We thus complete our description of behavior in terms of mental processes we know only in ourselves (such as feeling, emotion, will) but infer from external evidence to take place in other animals.

In describing a simple reflex action, for instance, the physico-chemical chain of events may appear to be so completely known that the corresponding mental events are usually not mentioned at all, their existence may even be denied. On the contrary, when describing complex behavior when impulses from external or internal stimuli modify each other before the final result is translated into action, it is the intervening physico-chemical processes which are unknown and perhaps ignored, and the action is said to be voluntary or prompted by emotion or the will.

The point I wish to make, however, is that the actions and behavior of organisms are responses, are characters in the sense described in the earlier part of this address. They are inherited, they vary, they are selected, and evolve like other characters. The distinction so often drawn by psychologists between instinctive behavior said to be inherited and intelligent behavior said to be acquired is as misleading and as little justified in this case as in that of structural characters. Time will not allow me to develop this point of view, but I will only mention that instinctive behavior is carried out by a mechanism developed under the influence of stimuli, chiefly internal, which are constantly present in the normal enviromental conditions, while intelligent behavior depends on responses called forth by stimuli which may or may not be present. Hence, the former is, but the latter may or

may not be inherited. As in other cases, the distinction lies in the factors and conditions which produce the results. Instinctive and intelligent behavior are usually, perhaps always, combined, and one is not more primitive or lower than the other.

It would be a mistake to think that these problems concerning factors and environment, heredity and evolution, are merely matters of academic interest. Knowledge is power, and in the long run it is always the most abstruse researches that yield the most practical results. Already, in the effort to keep up and increase our supply of food, in the constant fight against disease, in education, and in the progress of civilization generally, we are beginning to appreciate the value of knowledge pursued for its own sake. Could we acquire the power to control and alter at will the factors of inheritance in domesticated animals and plants, and even in man himself, such vast results might be achieved that the past triumphs of the science would fade into insignificance.

Zoology is not merely a descriptive and observational science, it is also an experimental science. For its proper study and the practical training of students and teachers alike, well-equipped modern laboratories are necessary. Moreover, if there is to be a useful and progressive school contributing to the advance of the science, ample means must be given for research in all its branches. Life doubtless arose in the sea, and in the attempt to solve most of the great problems of biology the greatest advances have generally been made by the study of the lower marine organisms. It would be a thousand pities, therefore, if Edinburgh did not avail itself of its fortunate position to offer to the student opportunities for the practical study of marine zoology.

In his autobiography, Darwin complains of the lack of facilities for practical work-the same need is felt at the present time. He would doubtless have been gratified to see the provision made since his day and the excellent use to which it has been put; but what seems adequate to one generation becomes insuffi

cient for the next. We earnestly hope that any appeal that may be made for funds to improve this Department of Zoology may meet with the generous response it certainly de

serves.

EDWIN S. GOODRICH

THE SPIRIT OF RESEARCH

THE recent World War emphasized the importance of scientific investigation and as a result there has followed a vigorous campaign to promote research in America. In consequence a great deal has been published recently concerning the mechanism of research; how we may cooperate; how the large university with superior equipment may help the teacher in the small institution to keep alive the hope that is within him to do research work; we have bulletins issued from time to time which bring certain fields of knowledge up-to-date; we have compendia on the technique of research; in a host of different ways the machinery for doing research is being cleaned and oiled and must run infinitely better than it has in the past. This is all exceeedingly important and must be done if we are to take a share in the program of scientific investigation. Back of all this machinery, however, must be human minds and the progress we make in the search for truth is going to depend on the spirit which animates these human minds guiding this machinery of research and taking part in the actual investigation of the many unsolved problems about us and trying to

Read the world's old riddles well.

In other words, the motives which prompt men to spend long hours and sleepless nights trying to fathom the depths of the unknown will determine the success individuals have in their work.

As one goes over the records of human achievements in history, there is developed in the reader a sense that the great achievements of the world have been in the realm of the spiritual. (Using that term in its broadest meaning.) The Magna Charta, the advent of the Pilgrim Fathers, the Boston

Tea Party, the Declaration of Independence, the Emancipation Proclamation are events and articles having the greatest spiritual significance. Great because they were staged for the uplift of the masses and not for the aggrandizement of the few as the failures of Alexander, Napoleon and William the Second are glaring examples.

It would seem that lessons of immense value to us might be gleaned from history as an aid in stimulating the spirit of research. What have the ancients to offer us! If achievement comes by means of spiritual forces then the animus of research must be spiritualized. Too much have we strayed from the simplicity of spirit which ruled the mind of the savant on the isle of Penikese who had

come in search of truth Trying with uncertain key Door by door of mystery.

Too much have we been stimulated by personal ambition in our "search for truth." Promotion, because of the amount of research we do is not the spiritualization sought for in this plea. The fundamental virtue of the investigator is a passion for truth whatever it be and through whatever channels it may come. As Bosworth says,

One's only safety consists in a fair treatment of facts. One fact fairly treated leads to another, and this to another. Facts treated as they ought to be treated lead always to a larger life.

This means not only a larger life for the investigator but more particularly for the great human family about him. Imbued with this spirit the seeker after truth goes in its search with the altruistic ambition of making the world a better place to live in, in every sense of the word "making it safe for democracy." Not of the sunlight, Not of the moonlight, Not of the starlight! O young Mariner, Down to the haven Call your companions, Launch your vessel, And crowd your canvas, And, e'er it vanishes

Over the margin,

After it, follow it, Follow the gleam.

There is a grave danger for the spirit of research when the chief criterion for the advancement of an individual in his position is his ability to turn out voluminous material describing his experiments. This motive prompting the researcher tends more and more to satisfy personal ambition. There will gradually appear a greater amount of polemical writing and controversies over priority of discovery. Nor is this all or the worst of the results attained by such a stimulus to research. Inaccuracies and carelessness in obtaining results are inevitable, it is the logical outcome of a system where bulk and not quality weighs so heavily in seeking promotion. This tendency we are all aware of, not only in individuals but we recognize it as characteristic of nations as well. After all what difference does it make through whom truth is revealed if all can enjoy its fruits?

On the other hand, that land whose cricket and other sports have imbued its citizens with a sense of the sport for the game's sake" has contributed a succession of epoch makers in the field of science that makes one wonder whence the inspiration of it all. One can not imagine the immortal Newton worrying very much about the status of his position because the first computation concerning the force of gravity due to the earth at the moon did not yield results as he had anticipated. To him and a great host of his fellow countrymen succeeding him it was sufficient to seek first the kingdom of truth, leaving it to others to judge whether the honors of earth, if they had any value, would be added as a natural result of ability. Is it not worth while for us of America, young in the research field, to consider seriously the motives which are to prompt our endeavors in the search for truth? The first motive leads to mediocre results while the latter is characterized by those discoveries which are epoch making. Shall personal ambition or the desire to be a friend to man surge

through our endeavors? One class who followed the gleam of truth was hypocritical, men who seemed to have, and wished to seem to have the prestige of scientific distinction without actually possessing it. The other class adopted as their ideal those words which must be the true sentiment of every creative worker in every field of human knowledge: And only the Master shall praise us, and only the Master shall blame;

And no one shall work for money, and no one shall work for fame;

But each for the joy of working, and each, in his separate star,

Shall draw the Thing as he sees It for the God of
Things as they are."
S. R. WILLIAMS

OBERLIN COLLEGE, OBERLIN, OHIO

THE CONCENTRATION OF HYDROGEN IONS IN THE SOIL

A PAPER with the above title has been published in Danish in the reports from the Carlsberg Laboratory (Meddelelser fra Carlsberg Laboratoriet), Vol. 15, Nr. 1. An English edition of this paper will soon be published in Comptes-Rendus des Travaux du Laboratoire Carlsberg, Vol. 15, Nr. 1.

The paper contains an account of researches carried on during the years 1916 and 1920 in order to ascertain the importance of the concentration of hydrogen ions with regard to the natural distribution of plants. Analyses were made of a series of Danish plant formations with regard to their botanical constitution, and at the same time samples of the soil were taken from the places in question, and the concentration of hydrogen ions determined. In natural Danish soil it was found to vary from 3.4 to 8.0 as expressed in pH values.

When comparing the botanical analysis of the formations with the physico-chemical analysis of the soil it was immediately seen that there is rather a fixed and constant relationship between the constitution of the vegetation and the concentration of hydrogen ions in the soil, because important variations of the latter are always accompanied by vari

ations of the constitution of the vegetation when the other factors remain the same, whereas habitats with about the same concentration of hydrogen ions and equal with regard to light and moisture carry about the same vegetation. When the material collected was statistically investigated, it was further proved that many species are only found on soil where the concentration of hydrogen ions is within a certain range of concentration of hydrogen ions characteristic for each single species. Within this is found another range with narrower limits, within which the species has its largest average frequency. It was further proved that it was possible to judge of the concentration of hydrogen ions in the soil from the constitution of the plant formations, when they did not consist of too few species; this holds good, for instance, for meadows.

The number of species found and the density of species (the number of species found on 0.1 sq. m.) were on the whole largest on soil near the neutral point; number of species and density of species become generally less as the concentration of hydrogen ions in the soil increases.

By a series of water-culture experiments it was proved that the species which are found only on very acid soil (acid soil plants) show the strongest growth in culture media with pH values near 4, whereas species which naturally grow only in soils that are neutral or but slightly acid or basic (alkaline soil plants) have the strongest growth in culture media, the pH values of which are between 6 and 7. In the slightly acid culture media in which the basic soil plants have their strongest growth the acid soil plants thrive badly and become chlorotic.

According to the theory of Hartwell and Pember1 basic soil plants can not thrive in very acid soils, not because these plants can not stand so high a concentration of hydrogen ions as the acid soil plants, but because the 1 Hartwell, B. L., and Pember, F. R., 1918, 66 The presence of aluminum as a reason for the difference in the effect of so-called acid soil on barley and rye," Soil Science, 6, 259.

very acid soils contain small quantities of dissolved aluminum compounds, which are said to be poisonous for the basic soil plants and not for the acid soil plants. This theory has been proved not to be generally valid, as experiments have shown that aluminum ions are not poisonous for all basic soil plants, generally speaking.

According to Bear2 and others acid soil plants can make use of the nitrogen in ammonia, whereas basic soil plants require nitrate nitrogen, which makes it impossible for them to thrive in very acid soil in which nitrification is weak or wanting. Experiments showed that nitrogen from ammonia and from nitrate nitrogen are of the same value for acid soil plants and for basic soil plants, when the plants were cultivated at constant pH. If on the other hand the pH is not kept constant, the plants make the solution more acid, when the source of nitrogen is a salt of ammonia (including thereby ammonia). In this case the basic soil plants soon die, because the solution becomes too acid. The acid soil plants on the other hand last longer as they are more tolerant of acid If the source of nitrogen is a nitrate (nitrate of ammonia excepted), the plants make the solution more alkaline and the plants die, after having first become chlorotic. The chlorosis takes place for acid soil plants when the pH value of the culture medium has the culture medium has reached a pH value reached 6.0, but for basic soil plants not till of about 7.0.

The investigations prove that the quantity of nutritive substances does not largely influence the distribution of plants. This is opposed to the results of some investigators, who consider that the acid soils are poor and the neutral and basic soils rich in such substances. It has been proved that basic soils exist which are very poor in nutritive substances, and their vegetation does not resemble that of very acid soils, which are poor in nutritive substances.

2 Bear, F. E., 1917, "A correlation between bac terial activity and lime requirement of soils," Soil Science, 4, 435.