Chapter XIII: Appendix: A List of Sources (5)

Even from these few citations it will appear how varied are the lines of attack of a single biological problem; for here we see, at the hands of a few workers, a great variety of forms of life--radiates, insects, vertebrates, low marine plants and high terrestrial ones--made to contribute to the elucidation of various phases of one general topic, the all-important subject of heredity. All these studies are conducted in absolute independence, and to casual inspection they might seem to have little affinity with one another; yet in reality they all trench upon the same territory, and each in its own way tends to throw light upon a topic which, in some of its phases, is of the utmost practical importance to the human family. It is a long vault from the embryo of an obscure sea-weed to the well-being of man, yet it may well happen--so wide in their application are the general life principles--that study of the one may point a practical moral for the other.

Indeed, it constantly happens that the student of biology, while gazing through his microscope, hits upon discoveries that have the most far-removed implications. Thus a few years ago it was discovered that when a cell is about to bisect itself and become two cells, its nucleus undergoes a curious transformation. Within the nuclear substance little bodies are developed, usually threadlike in form, which take on a deep stain, and which the biologist calls chromosomes. These chromosomes vary in number in the cells of different animals, but the number is always the same for any given species of animal. If one were to group animate beings in classes according to this very fundamental quality of the cells he would have some very curious relations established. Thus, under the heading "creatures whose cells have twenty-four chromosomes," one would find beings so different as "the mouse, the salamander, the trout, and the lily," while the sixteen-chromosome group would introduce the very startling association of the ox, the guinea-pig, the onion, and man himself. But whatever their number, the chromosomes are always exactly bisected before the cell divides, one-half being apportioned to each of the two cells resulting from the division.

Now the application is this: It was the study of these odd nuclear structures and their peculiar manouvrings that, in large measure, led Professor Weismann to his well-known theory of heredity, according to which the acquired traits of any being are not transmissible to the offspring. Professor Weismann came to believe that the apportionment of the nuclear substance, though quantitatively impartial, is sometimes radically uneven in quality; in particular, that the first bisection of the egg-cell, which marks the beginning of embryonic development, produces two cells utterly different in potentiality, the one containing the "body plasm," which is to develop the main animal structures, the other encompassing the "germ plasm," by which the racial integrity is [to be preserved. Throughout the life of the individual, he believed, this isolation continued; hence the assumed lack of influence of acquired bodily traits upon the germ plasm and its engendered offspring. Hence, also, the application of the microscopical discovery to the deepest questions of human social evolution.

Every one will recall that this theory, born of the laboratory, made a tremendous commotion in the outside world. Its application to the welfare and progress of humanity gave it supreme interest, and polemics unnumbered were launched in its favor and in its condemnation. Eager search was made throughout the fields of botany and zoology for new evidence pro or con. But the definitive answer came finally from the same field of exploration in which the theory had been originated--the world of the cell--and the Marine Biological Laboratory was the seat of the new series of experiments which demonstrated the untenability of the Weismannian position. Most curious experiments they were, for in effect they consisted of the making of two or more living creatures out of one, in the case of beings so highly organized as the sea-urchins, the little fishlike vertebrate, amphioxus, and even the lower orders of true fishes. Of course the division of one being to form two is perfectly familiar in the case of those lowly, single-celled creatures such as the protozoa and the bacteria, but it seems quite another matter when one thinks of cutting a fish in two and having two complete living fish remaining. Yet this is virtually what the biologists did.

Let me hasten to add that the miraculous feat was not accomplished with an adult fish. On the contrary, it is found necessary to take the subject quite at the beginning of its career, when it consists of an egg-cell in the earliest stages of proliferation. Yet the principle is quite the same, for the adult organism is, after all, nothing more than an aggregation of cells resulting from repeated divisions (growth accompanying) and redivisions of that original egg-cell. Considering its potentialities, the egg-cell, seemingly, is as much entitled to be considered an individual as is the developed organism. Yet it transpires that the biologist has been able so to manipulate a developing egg-cell, after its bisection, that the two halves fall apart, and that each half (now become an independent cell) develops into a complete individual, instead of the half-individual for which it seemed destined. A strange trick, that, to play with an individual _Ego_, is it not? The traditional hydra with its reanimating heads was nothing to this scientific hydra, which, when bisected bodily, rises up calmly as two whole bodies.

But even this is not the full measure of the achievement, for it has been found that in some cases the experiment may be delayed until the developing egg has made a second bisection, thus reaching the four-cell stage, when four completely formed individuals emerge from the dismembered egg. And in the case of certain medusae, success has attended experiments made at the eight-cell and even at the sixteen-cell stage of development, the creature which had got thus far on its career in single blessedness becoming eight or sixteen individuals at the wave of the enchanted wand--that is to say, the dissecting-needle--of the biologist. All of which savors of conjury, but is really only matter-of-fact biological experiment--experiment, however, of which the implications by no means confine themselves to matters of fact biological. For clearly the fact that the separated egg-cells grow into complete individuals shows that Weismann's theory, according to which one of the cells contained only body plasm, the other only germ plasm, is quite untenable. Thus the theory of the non-transmissibility of acquired characters is deprived of its supposed anatomical support and left quite in the air, to the imminent peril of a school of sociologists who had built thereon new theories of human progress. Also the question of the multiplied personalities clearly extends far beyond the field of the biologist, and must be turned over to the consideration of the psychologist--if, indeed, it does not fall rather within the scope of the moralist.

But though it thus often chances that the biologist, while gazing stoically through his microscope, may discover things in his microcosm that bear very closely upon the practical interests of the most unscientific members of the human family, it would be a mistake to suppose that it is this class of facts that the worker is particularly seeking. The truth is that, as a rule, the pure biologist is engaged in work for the love of it, and nothing is further from his thoughts than the "practical" bearings or remote implications of what he may discover. Indeed, many of his most hotly pursued problems seem utterly divorced from what an outsider would call practical bearings, though, to be sure, one can never tell just what any new path may lead to. Such, for example, is the problem which, next to questions of cell activities, comes in for perhaps as large a share of attention nowadays as any other one biological topic;--namely, the question as to just which of the various orders of invertebrate creatures is the type from which vertebrates were evolved in the past ages--in other words, what invertebrate creature was the direct ancestor of the vertebrates, including man. Clearly it can be of very little practical importance to man of to-day as to just who was his ancestor of several million years ago. But just as clearly the question has interest, and even the layman can understand something of the enthusiasm with which the specialist attacks it.

As yet, it must be admitted, the question is not decisively answered, several rival theories contending for supremacy in the case. One of the most important of these theories had its origin at the Naples laboratory; indeed, Dr. Dohrn himself is its author. This is the view that the type of the invertebrate ancestor is the annelid--a form whose most familiar representative is the earth-worm. The many arguments for and against accepting the credentials of this unaristocratic ancestor cannot be dwelt upon here. But it may be consolatory, in view of the very plebeian character of the earth-worm, to know that various of the annelids of the sea have a much more aristocratic bearing. Thus the filmy and delicately beautiful structures that decorate the pleasant home of the quaint little seahorse in the aquarium--structures having more the appearance of miniature palm-trees than of animals--are really annelids. One can view Dr. Dohrn's theory with a certain added measure of equanimity after he learns this, for the marine annelids are seen, some of them, to be very beautiful creatures, quite fitted to grace their distinguished offspring should they make good their ancestral claims.

These glimpses will suffice, perhaps, to give at least a general idea of the manner of thing which the worker at the marine laboratory is seeking to discover when he interrogates the material that the sea has given him. In regard to the publication of the results of work done at the Naples laboratory, the same liberal spirit prevails that actuates the conduct of the institution from first to last. What the investigator dis* covers is regarded as his own intellectual property, and he is absolutely free, so far as the management of this institution is concerned, to choose his own medium in giving it to the world. He may, and often does, prefer to make his announcements in periodicals or books issued in his own country and having no connection whatever with the Naples laboratory. But, on the other hand, his work being sufficiently important, he may, if he so desire, find a publisher in the institution itself, which issues three different series of important publications, under the editorship of Professor Mayer.

One of these, entitled _Mittheilungen aus der Zoologische Station zu Neapel_, permits the author to take his choice among four languages--German, English, French, or Italian. It is issued intermittently, as occasion requires. The second set of publications consists of ponderous monographs upon the fauna and flora of the Gulf of Naples. These are beautifully illustrated in color, and sometimes a single volume costs as much as seventeen thousand dollars to issue. Of course only a fraction of that sum is ever recovered through sale of the book. The third publication, called _Zoologischen Jahresbericht_, is a valuable résumé of biological literature of all languages, keeping the worker at the laboratory in touch with the discoveries of investigators elsewhere.

The latter end is attained further by the library of the institution, which is supplied with all the periodicals of interest to the biologist and with a fine assortment of technical books. The library-room, aside from its printed contents, is of interest because of its appropriate mural decorations, and because of the bronze portrait busts of the two patron saints of the institution, Von Baer and Darwin, which look down inspiringly upon the reader.

All in all, then, it would be hard to find a deficiency in the Stazione Zoologica as an instruement of biological discovery. A long list might be cited of the revelations first brought to light within its walls. And yet, as it seems to me, the greatest value of this institution as an educational factor in science--as a biological lever of progress--does not depend so much upon the tangible revelations of fact that have come out of its laboratories as upon other of its influences. Scientific ideas, like all other forms of human thought, move more or less in shoals. Very rarely does a great discovery emanate from an isolated observer. The man who cannot come in contact with other workers in kindred lines becomes more or less insular, narrow, and unfitted for progress. Nowadays, of course, the free communication between different quarters of the globe takes away somewhat from the insularity of any quarter, and each scientist everywhere knows something of what the others are doing, through wide-spread publications. But this can never altogether take the place of personal contact and the inspirational communication from man to man. Hence it is that a rendezvous, where all the men of a craft go from time to time and meet their fellows from all over the world, has an influence for the advancement of the guild which is enormous and unequivocal, even though difficult of direct demonstration.

This feature, then, it seems to me, gives Dr. Dohrn's laboratory its greatest value as an educational factor, as a moving force in the biological world. It is true that the new-comer there is likely to be struck at first with a sense of isolation, and to wonder at the seeming exclusiveness of the workers, the self-absorption of each and every one. Outside the management, whom he meets necessarily, no one pays the slightest attention to him at first, or seems to be aware of his existence. He is simply assigned to a room or table, told to ask for what he wants, and left to his own devices. As he walks along the hallways he sees tacked on the doors the cards of biologists from all over the world, exposing names with which he has long been familiar. He understands that the bearers of the names are at work within the designated rooms, but no one offers to introduce him to them, and for some time, perhaps, he does not so much as see them, nor would he recognize them if he did. He feels strange and isolated in the midst of this stronghold of his profession.

But soon this feeling leaves him. He begins to meet his fellow-workers casually here and there--in the hallways, at the distributing-tanks, in the library. There are no formal gatherings, and there are some workers who never seem to affiliate at all with the others; but in the long-run, here as elsewhere, kindred spirits find one another out; and even the unsocial ones take their share, whether or no, in the indefinable but very sensible influence of massed numbers. Presently some one suggests to the new-comer that he join some of the others of a Wednesday or Saturday evening, at a rendezvous where a number of them meet regularly. He goes, under escort of his sponsor, and is guided through one of those narrow, dark, hill-side streets of Naples where he would hardly feel secure to go alone, to a little wine-shop in what seems a veritable dungeon--a place which, if a stranger in Naples, he would never even remotely think of entering. But there he finds his confrères of the laboratory gathered about a long table, with the most conglomerate groups of Neapolitans of a seemingly doubtful class at their elbows. Each biologist has a caraffa of light wine on the table before him, and all are smoking. And, staid men of science that they are, they are chattering away on trivial topics with the animation of a company of school-boys. The stock language is probably German, for this bohemian gathering is essentially a German institution; but the Germans are polyglots, and you will hardly find yourself lost in their company, whatever your native tongue.

Your companions will tell you that for years the laboratory fraternity have met twice a week at this homely but hospitable establishment. The host, honest Dominico Vincenzo Bifulco, will gladly corroborate the statement by bringing out for inspection a great blank-book in which successive companies of his guests from the laboratory have scrawled their names, written epigrams, or made clever sketches. That book will some day be treasured in the library of a bibliophile, but that will not be until Bifulco is dead, for while he lives he will never part with it.

One comes to look upon this bohemian wine-shop as an adjunct of the laboratory, and to feel that the free-and-easy meetings there are in their way as important for the progress of science as the private séances of the individual workers in the laboratory itself. Not because scientific topics are discussed here, though doubtless that sometimes happens, but because of that vitalizing influence of the contact of kindred spirits of which I am speaking, and because this is the one place where a considerable number of the workers at the laboratory meet together with regularity.

The men who enter into such associations go out from them revitalized, full of the spirit of propaganda. Returned to their own homes, they agitate the question of organizing marine laboratories there; and it is largely through the efforts of the graduates, so to say, of the Naples laboratory that similar institutions have been established all over the world.

Thanks largely to the original efforts of Dr. Dohrn, nearly all civilized countries with a coast-line now have their marine laboratories. France has half a dozen, two of them under government control. Russia has two on the Black Sea and one on the French Mediterranean coast. Great Britain has important stations at St. Andrews, at Liverpool, and at Plymouth. The Scandinavian peninsula has also three important stations. Germany shows a paucity by comparison, which, however, is easily understood when one reflects that the mother-laboratory at Naples is essentially a German institution despite its location.

The American stations are located at Woods' Holl and at Cold Spring Harbor, on opposite coasts of Long Island Sound. The Japanese station is an adjunct of Tokio University. For the rest, the minor offspring of the Naples laboratory are too numerous to be cited here. Nor can I enter into any details regarding even the more important ones. Each in its way enters into the same general line of work, varying the details according to the bent of mind of individual directors and the limitations of individual resources. But in the broader outlines the aim of all is the same, and what we have seen at Naples is typical of what is best in all the others.

VI. ERNST HAECKEL AND THE NEW ZOOLOGY

THE DREAM CITY

THE train crept on its tortuous way down the picturesque valley of the little Saale. At last we saw, high above us, on a jutting crag, three quaint old castles, in one of which, as we knew from our _Baedeker_; Goethe at one time lived. We were entering the region of traditions. Soon we knew we should be passing that famous battle-field on which Napoleon, in 1806, sealed the fate of Germany for a generation. But this spot, as seen from the car window, bore no emblem to distinguish it, and before we were quite sure that we had reached it we had in point of fact passed on, and the train was coming to a stop. "Jena!" called the guard, and the scramble for "luggage" began, leaving us for the moment no place for other thoughts than to make sure that all our various parcels were properly dragged out along with ourselves. For a wonder no Dienstman appeared to give us aid--showing how unexpected is the arrival of any wayfarer at this untoward season--and for a moment one seemed in danger of being reduced to the unheard-of expedient of carrying one's own satchel. But, fortunately, one is rescued from this most un-German predicament by the porter of a waiting hotel omnibus, and so at last we have time to look about us, and to awaken to a realizing sense that we have reached the land of traditions; that we have come to Mecca; that we are in the quondam home of Guericke, Fichte, Goethe, Schiller, Oken, and Gagenbaur; in the present home of Haeckel.

The first glimpse of a mountain beaming down at us from across the way was in admirable conformity with our expectations, but for the rest, the vicinage of the depot presented a most distressing air of modernity. A cluster of new buildings--some of them yet unfinished--stared back at us and the mountain with the most barefaced aspect of cosmopolitanism. Was this, then, Jena, the home of traditions? Or were we entering some Iowa village, where the first settlers still live who but yesterday banished the prairie-dog and the buffalo?

But this disappointment and its ironical promptings were but fleeting. Five minutes' drive and we were in the true Jena with the real flavor of mediaeval-ism about us. Here is the hostelry where Luther met the Swiss students in 1522. There is nothing in that date to suggest our Iowa village, nor in the aspect of the hostelry itself, thank fortune. And there rises the spire of the city church, up the hill yonder, which was aging, as were most of the buildings that still flank it, when Luther made that memorable visit. America was not discovered, let alone Iowa, when these structures were erected. Now, sure enough, we are in the dream city.

A dream city it truly seems, when one comes to wander through its narrow, tortuous streets, between time-stained walls, amid its rustic population. Coming from Berlin, from Dresden, from Leipzig--not to mention America--one feels as if he had stepped suddenly back two or three centuries into the past. There are some evidences of modernity that mar the illusion, to be sure; but the preponderance of the old-time emblems is sufficient to leave the mind in a delightful glow of reminiscences. As a whole, the aspect of the central portion of the village--of the true Jena--cannot greatly have changed since the days when Luther stopped here on his way to Wittenberg; surely not since 1662, when the mighty young Leibnitz, the Aristotle of Germany, came to Jena to study under Weigel, the most famous of German mathematicians of that century. Here and there an old house has been demolished, to be sure; even now you may see the work of destruction going on, as a new street is being cut through a time-honored block close to the old church. But in the main the old thoroughfares run hither and thither, seemingly at random, as of old, disclosing everywhere at their limits a sky-line of picturesque gables, and shut in by walls that often are almost canon-like in narrowness; while the heavy, buttressed doors and the small, high-placed windows speak of a time when every house partook of the nature of the fortress.

The footway of the thoroughfares has no doubt vastly changed, for it is for the most part paved now--badly enough, to be sure, yet, after all, paved as no city was in the good old days when garbage filled the streets and cleanliness was an unknown virtue. The Jena streets of to-day are very modern in their cleanliness; yet a touch of medievalism is retained in that the main work of cleaning is done by women. But, for that matter, it seems to the casual observer as if the bulk of all the work here were performed by the supposedly weaker sex. Certainly woman is here the chief beast of burden. In every direction she may be seen, in rustic garb, struggling cheerily along under the burden of a gigantic basket strapped at her back. You may see the like anywhere else in Germany, to be sure, but not often elsewhere in such preponderant numbers. And scarcely elsewhere does the sight jar so little on one's New-World sensibilities as in the midst of this mediaeval setting. One is even able to watch the old women sawing and splitting wood in the streets here, with no thought of anything but the picturesque-ness of the incident.

If one follows a band of basket-laden women, he will find that their goal is that focal-point of every old-time city, the market-place. There arrived, he will witness a scene common enough in Europe but hardly to be duplicated anywhere in America. Hundreds of venders of meat, fish, vegetables, cloths, and household utensils have their open-air booths scattered all across the wide space, and other hundreds of purchasers are there as well. Quaint garbs and quainter faces are everywhere, and the whole seems quite in keeping with the background of fifteenth-century houses that hedges it in on every side. Could John the Magnanimous, who rises up in bronze in the midst of the assembly, come to life, he would never guess that three and a half centuries have passed since he fell into his last sleep.

This same John the Magnanimous it was who founded the institution which gives Jena its fame and distinguishes it from all the other quaint hypnotic clusters of houses that nestle similarly here and there in other picturesque valleys of the Fatherland--I mean, of course, its world-renowned university. It is but a few minutes' walk from the market-place, past the home where Schiller once lived and through the "street" scarcely more than arms'-breadth wide beyond, to the site of the older buildings of the university. Inornate, prosaic buildings they are, unrelieved even by the dominant note of picturesqueness; rescued, however, from all suggestion of the commonplace by the rugged ruins of the famed "powder-tower" jutting out from the crest of the hill just above, by the spire of the old church which seems to rise from the oldest university building itself, and by the mountain peaks that jut up into view far beyond.

If you would enter one of the old buildings there is naught to hinder. Go into one of the lecture-halls which chances at the moment to be unoccupied, and you will see an array of crude old benches for seats that look as if they might have been placed there at the very inaugural of the institution. The boards that serve for desks, if you scan them closer, you will find scarred all over with the marks of knives, showing how some hundreds of successive classes of listeners have whiled away the weary lecture-hours. Not a square inch can you find of the entire desk surface that is un-scarred. If one would woo a new sensation, he has but to seat himself on one of these puritanical old benches and conjure up in imagination the long series of professors that may have occupied the raised platform in front, recalling the manner of thought and dogma that each laid down as verity. He of the first series appears in the garb of the sixteenth century, with mind just eagerly striving to peer a little way out of the penumbra of the Renaissance. The students who carve the first gashes in the new desks will learn, if perchance they listen in intervals of whittling, that this World on which they live is perhaps not flat, but actually round, like a ball. It is debatable doctrine, to be sure, but we must not forget that Signor Columbus, recently dead, found land off to the west which is probably a part of the Asiatic continent. If the earth be indeed a ball, then the sun and stars whirl clear around it in twenty-four hours, travelling thus at an astonishing speed, for the sphere in which they are fastened is situated hundreds of miles away. The sun must be a really great ball of fire--perhaps a mile even in diameter. The moon, as is plain to see, is nearly as large. The stars, of course, are only sparks, though of great brilliancy. They are fixed in a different sphere from that of the sun. In still other spheres are the moon, and a small set of large stars called planets, of which latter there are four, in order that, with the sun, the moon, and the other stars, there may be made seven orders of heavenly bodies--seven being, of course, the magic number in accordance with which the universe is planned.

This is, in substance, the whole subject of astronomy, as that first professor must have taught it, even were he the wisest man of his time. Of the other sciences, except an elementary mathematics, there was hardly so much as an inkling taught that first class of students. You will find it appalling, as you muse, to reflect upon the amazing mixture of utter ignorance and false knowledge which the learned professor of that day brought to the class-room, and which the "educated" student carried away along with his degree. The one and the other knew Greek, Latin, and Bible history and doctrine. Beyond that their minds were as the minds of babes. Yet no doubt the student who went out from the University of Jena in the year 1550 thought himself upon the pinnacles of learning. So he was in his day and age, but could he come to life to-day, in the full flush of his scholarship, yonder wood-vender, plying her saw out here in front of the university building, would laugh in derision at his simplicity and ignorance. So it seems that, after all, the subjects of John the Magnanimous have changed more than a little during the three hundred and odd years that John himself, done in bronze, has been standing out there in the market-place.

THE CAREER OF A ZOOLOGIST

Had one time for it, there would be real interest in noting the steps by which the mental change in question has been brought about; in particular to note the share which the successive generations of Jena professors have taken in the great upward struggle. But we must not pause for that here. Our real concern, despite the haunting reminiscences, is not with the Jena of the past, but with the Jena of to-day; not with ghosts, but with the living personality who has made the Jena of our generation one of the greatest centres of progress in human thought in all the world. Jena is Jena to-day not so much because Guericke and Fichte and Hegel and Schiller and Oken taught here in the past, as because it has for thirty-eight years been the seat of the labors of Germany's greatest naturalist, one of the most philosophical zoologists of any country or any age, Professor Ernst Haeckel. It is of Professor Haeckel and his work that I chiefly mean to write, and if I have dwelt somewhat upon Jena itself, it is because this quaint, retired village has been the theatre of Haeckel's activities all the mature years of his life, and because the work he has here accomplished could hardly have been done so well elsewhere; some of it, for reasons I shall presently mention, could hardly have been done elsewhere at all--at least in another university.

It was in 1861 that young Dr. Haeckel came first to Jena as a teacher. He had made a tentative effort at the practice of medicine in Berlin, then very gladly had turned from a distasteful pursuit to the field of pure science. His first love, before he took up the study of medicine, had been botany, though pictorial art, then as later, competed with science for his favorable attention. But the influence of his great teacher, Johannes Müller, together with his medical studies, had turned his attention more directly to the animal rather than vegetable life, and when he left medicine it was to turn explicitly to zoology as a life study. Here he believed he should find a wider field than in art, which he loved almost as well, and which, it may be added, he has followed all his life as a dilettante of much more than amateurish skill. Had he so elected, Haeckel might have made his mark in art quite as definitely as he has made it in science. Indeed, even as the case stands, his draughtsman's skill has been more than a mere recreation to him, for without his beautiful drawings, often made and reproduced in color, his classical monographs on various orders of living creatures would have lacked much of their present value.

Moreover, quite aside from these merely technical drawings, Professor Haeckel has made hundreds of paintings purely for recreation and the love of it, illustrating--and that too often with true artistic feeling for both form and color--the various lands to which his zoological quests have carried him, such as Sicily, the Canaries, Egypt, and India. From India alone, after a four-months' visit, Professor Haeckel brought back two hundred fair-sized water-colors, a feat which speaks at once for his love of art and his amazing industry.

I dwell upon this phase of Professor Haeckel's character and temperament from the very outset because I wish it constantly to be borne in mind, in connection with some of the doctrines to be mentioned presently, that here we have to do with no dry-as-dust scientist, cold and soulless, but with a broad, versatile, imaginative mind, one that links the scientific and the artistic temperaments in rarest measure. Charles Darwin, with whose name the name of Haeckel will always be linked, told with regret that in his later years he had become so steeped in scientific facts that he had lost all love for or appreciation of art or music. There has been no such mental warping and atrophy in the mind of Ernst Haeckel. Yet there is probably no man living to-day whose mind contains a larger store of technical scientific facts than his, nor a man who has enriched zoology with a larger number of new data, the result of direct personal observation in field or laboratory.

How large Haeckel's contribution in this last regard has been can be but vaguely appreciated by running over the long list of his important publications, though the list includes more than one hundred titles, unless it is understood that some single titles stand for monographs of gigantic proportions, which have involved years of labor in the production. Thus the text alone of the monograph on the radiolarians, a form of microscopic sea-animalcule (to say nothing of the volume of plates), is a work of three gigantic volumes, weighing, as Professor Haeckel laughingly remarks, some thirty pounds, and representing twelve years of hard labor. This particular monograph, by-the-bye, is written in English (of which, as of several other languages, Professor Haeckel is perfect master), and has a history of more than ordinary interest. It appears that the radiolarians were discovered about a half-century ago by Johannes Müller, who made an especial-study of them, which was uncompleted at the time of his death in 1858. His monograph, describing the fifty species then known, was published posthumously. Haeckel, on whom the mantle of the great teacher was to fall, and who had been Müller's last pupil, took up the work his revered master had left unfinished as his own first great original _Arbeit_. He went to Messina and was delighted to find the sea there replete with radiolarians, of which he was able to discover one or two new species almost every day, until he had added one hundred and fifty all told to Müller's list, or more than triple the whole number previously known. The description of these one hundred and fifty new radiolarians constituted Haeckel's first great contribution to zoology, and won him his place as teacher at Jena in 1861.

Henceforth Haeckel was, of course, known as the greatest authority on this particular order of creatures. For this reason it was that Professor Murray, the naturalist of the famous expedition which the British government sent around the world in the ship _Challenger_, asked Haeckel to work up the radiolarian material that had been gathered during that voyage. Murray showed Haeckel a little bottle containing water, with a deposit of seeming clay or mud in the bottom. "That mud," he said, "was dredged up from the bottom of the ocean, and every particle of it is the shell of a radiolarian." "Impossible," said Haeckel. "Yet true," replied Murray, "as the microscope will soon prove to you."

So it did, and Professor Haeckel spent twelve years examining that mud under the microscope, with the result that, before he had done, he had discovered no fewer than four thousand new species of radiolarians, all of which, of course, had to be figured, described, and christened. Think of baptizing four thousand creatures, finding a new, distinct, and appropriate Latin name for each and every one, and that, too, when the creatures themselves are of microscopic size, and the difference between them often so slight that only the expert eye could detect it. Think, too, of the deadly tedium of labor in detecting these differences, in sketching them, and in writing out, to the length of three monster volumes, technical dissertations upon them.

To the untechnical reader that must seem a deadly, a veritably mind-sapping task. And such, indeed, it would prove to the average zoologist. But with the mind of a Haeckel it is far otherwise. To him a radiolarian, or any other creature, is of interest, not so much on its own account as for its associations. He sees it not as an individual but as a link in the scale of organic things, as the bearer of a certain message of world-history. Thus the radiolarians, insignificant creatures though they seem, have really taken an extraordinary share in building up the crust of the earth. The ooze at the bottom of the sea, which finally becomes metamorphosed into chalk or stone, is but the aggregation of the shells of dead radiolarians. In the light of such a rôle the animalcule takes on a new interest.

But even greater is the interest that attaches to every creature in regard to the question of its place in the organic scale of evolution. What are the homologies of this form and that? What its probable ancestry? What gaps does it bridge? What can it tell us of the story of animal creation? These and such like are the questions that have been ceaselessly before Haeckel's mind in all his studies of zoology. Hence the rich fountain of philosophical knowledge that has welled up from what otherwise might have been the most barren of laboratory borings. Thus from a careful investigation of the sponge Haeckel was led to his famous gastrula theory, according to which the pouchlike sponge-animalcule--virtually a stomach without members--is the type of organism on which all high organisms are built, so to speak--that is, out of which all have evolved.

This gastrula theory, now generally accepted, is one of Haeckel's two great fundamental contributions to the evolution philosophy with the history of which his life work is so intimately linked. The other contribution is the theory, even more famous and now equally undisputed, that every individual organism, in its em-bryological development, rehearses in slurred but unmistakable epitome the steps of evolution by which the ancestors of that individual came into racial being. That is to say, every mammal, for example, originating in an egg stage, when it is comparable to a protozoon, passes through successive stages when it is virtually in succession a gastrula, a fish, and an amphibian before it attains the mammalian status, because its direct ancestors were in succession, through the long geological ages, protozoons, gastrulae, fishes, amphibians before the true mammal was evolved. This theory cast a flood of light into many dark places of the Darwinian philosophy. It was propounded in 1866 in Professor Haeckel's great work on morphology, and it has ever since been a guiding principle in his important philosophical studies.

It was through this same work on morphology that Haeckel first came to be universally recognized as the great continental champion of Darwinism--the Huxley of Germany. Like Huxley, Haeckel had at once made the logical application of the Darwinian theory to man himself, and he sought now to trace the exact lineage of the human family as no one had hitherto attempted to fathom it. Utilizing his wide range of zoological and anatomical knowledge, he constructed a hypothetical tree of descent--or, if you prefer, ascent--from the root in a protozoon to the topmost twig or most recent offshoot, man. From that day till this Haeckel's persistent labors have been directed towards the perfection of that genealogical tree.

This work on morphology was much too technical to reach the general public, but in 1868 Haeckel prepared, at the instigation of his friend and confrère Gagenbaur, what was practically a popular abridgment of the technical work, which was published under the title of _The Natural History of Creation_. This work created a furor at once. It has been translated into a dozen languages, and has passed through nine editions in the original German. Through it the name of Haeckel became almost a household word the world over, and subject for mingled applause and opprobrium--applause from the unprejudiced for its great merit; opprobrium from the bigoted because of the unprecedented candor with which it followed the Darwinian hypothesis to its logical goal.

The same complete candor of expression has marked every stage of the unfolding of Professor Haeckel's philosophical pronouncements. This fact is the more remarkable because Professor Haeckel is, so far as I am aware, the only scientist of our generation who has felt at liberty to announce, absolutely without reserve, the full conclusions to which his philosophy has carried him, when these conclusions ran counter to the prevalent prejudices of his time. Some one has said that the German universities are oases of freedom. The remark is absolutely true of Jena. It is not true, I believe, in anything like the same degree of any other German university, or of any other university in the world. One thing before others that has endeared Jena to Haeckel, and kept him there in the face of repeated flattering calls to other universities, is that full liberty of spirit has been accorded him there, as he knew it would not be accorded elsewhere. "When a man comes into the atmosphere of Jena," says Professor Haeckel, "he perforce begins to think--there is no escape from it. And he is free to let his thoughts carry him whithersoever they honestly may. My beliefs," he added, "are substantially the beliefs of my colleagues in science everywhere, as I know from private conversations; but they, unlike myself, are not free to speak the full truth as they see it. I myself would not be tolerated elsewhere, as I am well aware. Had I desired to remain in Berlin, for example, I must have kept silent. But here in Jena one is free."

And he smiles benignly as he says it. The controversies through which he has passed and the calumnies of which he has been the target have left no scars upon this broad, calm spirit.

HAECKEL AS MAN AND TEACHER

It is indeed a delightful experience to meet Professor Haeckel in the midst of his charming oasis of freedom, his beloved Jena. To reach his laboratory you walk down a narrow lane, past Schiller's house, and the garden where Schiller and Goethe used to sit and where now the new observatory stands. Haeckel's laboratory itself is a simple oblong building of yellowish brick, standing on a jutting point of land high above the street-level. Entering it, your eye is first caught by a set of simple panels in the wall opposite the door bearing six illustrious names: Aristotle, Linne, Lamarck, Cuvier, Müller, Darwin--a Greek, a Swede, two Frenchmen, a German, and an Englishman. Such a list is significant; it tells of the cosmopolitan spirit that here holds sway.

The ground-floor of the building is occupied by a lecture-room and by the zoological collection. The latter is a good working-collection, and purports to be nothing else. Of course it does not for a moment compare with the collections of the museums in any large city of Europe or America, nor indeed is it numerically comparable with many private collections, or collections of lesser colleges in America. Similarly, when one mounts the stairs and enters the laboratory proper, he finds a room of no great dimensions and nowise startling in its appointments. It is admirably lighted, to be sure, and in all respects suitably equipped for its purpose, but it is by no means so large or so luxurious as the average college laboratory of America. Indeed, it is not to be mentioned in the same breath with the laboratories of a score or two of our larger colleges. Yet, with Haeckel here, it is unquestionably the finest laboratory in which to study zoology that exists in the world to-day, or has existed for the last third of a century.

Haeckel himself is domiciled, when not instructing his classes, in a comfortable but plain room across the hall--a room whose windows look out across the valley of the Saale on an exquisite mountain landscape, with the clear-cut mountain that Schiller's lines made famous at its focus. As you enter the room a big, robust man steps quickly forward to grasp your hand. Six feet or more in height, compactly built, without corpulence; erect, vigorous, even athletic; with florid complexion and clear, laughing, light-blue eyes that belie the white hair and whitening beard; the ensemble personifying at once kindliness and virility, simplicity and depth, above all, frank, fearless honesty, without a trace of pose or affectation--such is Ernst Haeckel. There is something about his simple, frank, earnest, sympathetic, yet robust, masculine personality that reminds one instinctively, as does his facial contour also, of Walt Whitman.

A glance about the room shows you at once that it is a place for study, and also that it is the room of the most methodical of students. There are books and papers everywhere, yet not the slightest trace of disorder. Clearly every book and every parcel of papers has a place, and is kept in that place. The owner can at any moment lay his hand upon anything he desires among all these documents. This habit of orderliness has had no small share, I take it, in contributing to Professor Haeckel's success in carrying forward many lines of research at the same time, and carrying all to successful terminations. Then there goes with it, as a natural accompaniment, a methodical habit of working, without which no single man could have put behind him the multifarious accomplishments that stand to Professor Haeckers credit.

Orderliness is not a more pronounced innate gift with Professor Haeckel than is the gift of initial energy to undertake and carry on work which leads to accomplishment--a trait regarding which men, even active men, so widely differ. But Professor Haeckel holds that whatever his normal bent in this direction, it was enormously strengthened in boyhood by the precepts of his mother--from whom, by-the-bye, he chiefly inherits his talents. "My mother," he says, "would never permit me to be idle for a moment. If I stood at a window day-dreaming, she would always urge me to be up and doing. 'Work or play,' she would urge, 'but do not stand idle.' Through this reiterated admonition, physical activity became a life-long habit with me, and work almost a necessity of my being. If I have been able to accomplish my full share of labors, this is the reason. I am never idle, and I scarcely know the meaning of _ennui_."

This must not be interpreted as meaning, however, that Professor Haeckel takes up a task and works at it all day long unceasingly. That is not the German method of working, and in this regard Professor Haeckel is a thorough German. "When I was a young man," he says, "I at one time, thanks to the persuasions of some English friends, became a convert to the English method of working, and even attempted to introduce it into Germany. But I soon relinquished it, and lapsed back into our German method, which I am convinced will produce better results for the average worker. The essential of this method is the long midday rest, which enables one late in the afternoon to begin what is virtually a new day's-work, and carry it out with vigor and without undue fatigue. Thus I, who am an early riser, begin work at five in summer and six in winter, after the customary light breakfast of coffee and rolls. I do not take a second breakfast at ten or eleven, as many Germans do, but work continuously until one o'clock, when I have dinner. This, with me, as with all Germans, is the hearty meal of the day. After dinner I perhaps take a half-hour's nap; then read the newspaper, or chat with my family for an hour, and perhaps go for a long walk. At about four, like all Germans, I take my cup of coffee, but without cake or other food. Then, at four, having had three full hours of brain-rest and diversion, I am ready to go to work again, and can accomplish four hours more of work without undue fatigue. At eight I have my rather light supper, and after that I attempt no further work, giving the evening to reading, conversation, or other recreation. I do not retire till rather late, as I require only five or six hours' sleep."

Such is the method of labor division that enables not Professor Haeckel only, but a host of other German brain-workers to accomplish enormous labors, yet to thrive on the accomplishment and to carry the ruggedness and health of youth far into the decades that are too often with our own workers given over to decrepitude. Haeckel at sixty-five looks as if he were good for at least a score of years of further effort. And should he fulfil the promise of his present rugged-ness, he will do no more than numbers of his colleagues in German universities have done and are doing. When one runs over the list of octogenarians, and considers at the same time the amount of the individual output of the best German workers, he is led to feel that Professor Haeckel was probably right in giving up the continuous-day method of labor and reverting to the German method.

In addition to the original researches that Professor Haeckel has carried out, to which I have already made some reference, there has, of course, been all along another large item of time-consumption to be charged up to his duties as a teacher. These, to be sure, are somewhat less exacting in the case of a German university professor than they are in corresponding positions in England or America. Thus, outside the hours of teaching, Professor Haeckel has all along been able to find about eight hours a day for personal, original research. When he told Professor Huxley so in the days of their early friendship, Huxley exclaimed: "Then you ought to be the happiest man alive. Why, I can find at most but two hours a day to use for myself."

So much for the difference between German methods of teaching, where the university professor usually confines his contact with the pupils to an hour's lecture each day, and the English system, according to which the lecturer is a teacher in other ways as well. Yet it must be added that in this regard Professor Haeckel is not an orthodox German, for his contact with his students is by no means confined to the lecture-hour. Indeed, if one would see him at his best, he must go, not to the lecture-hall, but to the laboratory proper during the hours when Professor Haeckel personally presides there, and brings knowledge and inspiration to the eager band of young dissectors who gather there. It will perhaps seem strange to the reader to be told that the hours on which this occurs are from nine till one o'clock of a day which is perhaps not devoted to class-room exercises in any other school of Christendom whatever--namely, the Sabbath. It is interesting to reflect what would be the comment on such a procedure in London, for example, where the underground railway trains even must stop running during the hours of morning service. But Jena is not London, and, as Professor Haeckel says, "In Jena one is free. It pleases us to have our Sabbath service in our tabernacle of science."

All questions of time aside, it is a favored body of young men who occupy the benches in the laboratory during Professor Haeckel's unique Sunday-morning service. Each student has before him a microscope and a specimen of the particular animal that is the subject of the morning's lesson. Let us say that the subject this morning is the crawfish. Then in addition to the specimens with which the students are provided, and which each will dissect for himself under the professor's guidance, there are scattered about the room, on the various tables, all manner of specimens of allied creatures, such as crabs, lobsters, and the like. There are dissected specimens also of the crawfish, each preparation showing a different set of organs, exhibited in preserving fluids. Then there are charts hung all about the room illustrating on a magnified scale, by diagram and picture, all phases of the anatomy of the subjects under discussion. The entire atmosphere of the place this morning smacks of the crawfish and his allies.