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.

The session begins with a brief off-hand discussion of the general

characteristics and affinities of the group of arthropoda, of which the

crawfish is a member. Then, perhaps, the professor calls the students

about him and gives a demonstration of the curious phenomena of

hypnotism as applied to the crawfish, through which a living specimen,

when held for a few moments in a constrained attitude, will pass into

a rigid "trance," and remain standing on its head or in any other

grotesque position for an indefinite period, until aroused by a blow

on the table or other shock. Such are some of the little asides, so to

speak, with which the virile teacher enlivens his subject and gives it

broad, human interest. Now each student turns to his microscope and his

individual dissection, and the professor passes from one investigator

to another with comment, suggestion, and criticism; answering questions,

propounding anatomical enigmas for solution--enlivening, vivifying,

inspiring the entire situation.

As the work proceeds, Professor Haeckel now and again calls the

attention of the entire class to some particular phase of the subject

just passing under their individual observation, and in the most

informal of talks, illustrated on blackboard and chart, clears up

any lurking mysteries of the anatomy, or enlivens the subject with an

incursion into physiology, embryology, or comparative morphology of the

parts under observation. Thus by the close of the session the student

has something far more than a mere first-hand knowledge of the anatomy

of the crawfish--though that in itself were much. He has an insight

also into a half-dozen allied subjects. He has learned to look on the

crawfish as a link in a living chain--a creature with physiological,

psychological, ontological affinities that give it a human interest not

hitherto suspected by the novitiate. And when the entire series of

Sunday-morning "services" has been carried through, one order after

another of the animal kingdom being similarly made tribute, the favored

student has gone far towards the goal of a truly philosophical zoology,

as different from the old-time dry-bones anatomy as the living crawfish

is different from the dead shell which it casts off in its annual

moulting time.

THE NEW ZOOLOGY

What, then, is the essence of this "philosophical zoology" of which

Haeckel is the greatest living exponent and teacher and of which his

pupils are among the most active promoters? In other words, what is the

real status, and the import and meaning, the _raison d'être_, if you

will, of the science of zoology to-day?

To clear the ground for an answer to that question, one must glance

backward, say half a century, and note the status of the zoology of that

day, that one may see how utterly the point of view has changed since

then; what a different thing zoology has become in our generation from

what it was, for example, when young Haeckel was a student at Jena back

in the fifties. At that time the science of zoology was a conglomeration

of facts and observations about living things, grouped about a set of

specious and sadly mistaken principles. It was held, following Cuvier,

that the beings of the animal kingdom had been created in accordance

with five preconceived types: the vertebrate, with a spinal column;

the articulate, with jointed body and members, as represented by the

familiar crustaceans and insects; the mollusk, of which the oyster and

the snail are familiar examples; the radiate, with its axially

disposed members, as seen in the starfish; and the low, almost formless

protozoon, most of whose representatives are of microscopic size. Each

of these so-called classes was supposed to stand utterly isolated from

the others, as the embodiment of a distinct and tangible idea. So, too,

of the lesser groups or orders within each class, and of the still more

subordinate groups, named technically families, genera; and, finally,

the individual species. That the grouping of species into these groups

was more or less arbitrary was of course to some extent understood, yet

it was not questioned by the general run of zoologists that a genus,

for example, represented a truly natural group of species that had been

created as variations upon one idea or plan, much as an architect

might make a variety of houses, no one exactly like any other, yet all

conforming to a particular type or genus of architecture--for example,

the Gothic or the Romanesque. That each of the groups defined by the

classifiers had such status as this was the stock doctrine of zoology,

as also that the individual species making up the groups, and hence

the groups themselves, maintained their individual identity absolutely

unaltered from the moment of their creation, throughout all successive

generations, to the end of their racial existence.

Such being the fundamental conception of zoology, it remained only for

the investigator to study each individual species with an eye to

its affinities with other species, that each might be assigned by a

scientific classification to the particular place in the original scheme

of creation which it was destined to occupy. Once such affinities

had been correctly determined and interpreted for all species, the

zoological classification would be complete for all time. A survey of

the completed schedule of classification would then show at a glance the

details of the preconceived system in accordance with which the members

of the animal kingdom were created, and zoology would be a "finished"

science.

In the application of this relatively simple scheme, to be sure, no end

of difficulties were encountered. Each higher animal is composed of so

many members and organs, of such diverse variations, that naturalists

could never agree among themselves as to just where a balance of

affinities between resemblances and differences should be struck;

whether, for example, a given species varied so much from the type

species of a genus--say the genus Gothic house--as to belong properly

to an independent genus--say Romanesque house; or whether, on the other

hand, its divergencies were still so outweighed by its resemblances as

to permit of its retention as an aberrant member of genus number one.

Perpetual quibbling over these matters was quite the order of the day,

no two authorities ever agreeing as to details of classification. The

sole point of agreement was that preconceived types were in question--if

only the zoologists could ever determine just what these types were.

Meantime, the student who supposed classifications to be matters of

moment, and who laboriously learned to label the animals and birds

of his acquaintance with an authoritative Latin name, was perpetually

obliged to unlearn what he had acquired, as a new classifier brought new

resources of hair-splitting pursuit of a supposed type or ideal to bear

on the subject. Where, for example, our great ornithologists of the

early part of the century, such as Wilson and Audubon, had classed all

our numerous hawks in a genus falco, later students split the group up

into numerous genera--just how many it is impossible to say, as no two

authorities agreed on that point. Wilson, could he have come back a

generation after his death, would have found himself quite at a loss to

converse with his successors about the birds he knew and loved so

well, using their technical names--though the birds themselves had not

changed.

Notwithstanding all the differences of opinion about matters of detail,

however, there was, nevertheless, substantial agreement about the

broader outlines of classifications, and it might fairly enough

have been hoped that some day, when longer study had led to finer

discrimination, the mysteries of all the types of creation would

be fathomed. But then, while this hope still seemed far enough from

realization, Charles Darwin came forward with his revolutionizing

doctrine--and the whole time-honored myth of "types" of creation

vanished in thin air. It became clear that the zoologists had been

attempting a task utterly Sisyphean. They had sought to establish

"natural groups" where groups do not exist in nature. They were eagerly

peering after an ideal that had no existence outside their imagination.

Their barriers of words could not be made to conform to barriers of

nature, because in nature there are no barriers.

What, then, was to be done? Should the whole fabric of classification

be abandoned? Clearly not, since there can be no science without

classification of facts about labelled groupings, however arbitrary.

Classifications then must be retained, perfected; only in future it must

be remembered that any classification must be more or less arbitrary,

and in a sense false; that it is at best only a verbal convenience, not

the embodiment of a final ideal. If, for example, we consider the very

"natural" group of birds commonly called hawks, we are quite justified

in dividing this group into several genera or minor groups, each

composed of several species more like one another than like the members

of other groups of species--that is, of other genera. But in so doing we

must remember that if we could trace the ancestry of our various species

of hawks we should find that in the remote past the differences that now

separate the groups had been less and less marked, and originally

quite non-existent, all the various species having sprung from a common

ancestor. The genera of to-day are cousin-groups, let us say; but the

parents of the existing species were of one brood, brothers and sisters.

And what applies to the minor groups called genera applies also, going

farther into the past, to all larger groups as well, so that in the last

analysis, all existing creatures being really the evolved and modified

descendants of one primordial type, it may be said that all animate

creation is but a single kind. In this broadened view the details of

classification ceased to have the importance once ascribed to them, and

the quibblings of the classifiers seem amusing rather than serious.

Yet the changed point of view left the subject by no means barren of

interest. For if the multitudinous creatures of the living world are

but diversified twig-lets of a great tree of ascent, spread by branching

from a common root, at least it is worth knowing what larger branches

each group of twiglets--representing a genus, let us say--has sprung

from. In particular, since the topmost twig of the tree is represented

by man himself and his nearest relatives, is it of human interest to

inquire just what branches and main stems will be come upon in tracing

back the lineage of this particular offshoot. This attempt had, perhaps,

no vast, vital importance in the utilitarian sense in which these terms

are oftenest used, but at least it had human interest. Important or

otherwise, it was the task that lay open to zoology, and apparently its

only task, so soon as the Darwinian hypothesis had made good its status.

The man who first took this task in hand, and who has most persistently

and wisely followed it, and hence the man who became the recognized

leader in the field of the new zoology, was, as I have already

intimated, Professor Haeckel. His hypothetical tree of man's lineage,

tracing the ancestry of the human family back to the earliest geological

times and the lowest orders of beings, has been familiar now for just

a third of a century. It was at first confessedly only a tentative

genealogy, with many weak limbs and untraced branches. It was perfected

from time to time, as new data came to hand, through studies of

paleontology, of embryology, and of comparative anatomy. It will be of

interest, then, to inquire just what is its status today and to examine

briefly Professor Haeckel's own most recent pronouncement regarding it.

Perhaps it is not worth our while here to go too far down towards the

root of the genealogical tree to begin our inquiry. So long as it is

admitted that the remote ancestry is grounded in the lowest forms of

organisms, it perhaps does not greatly matter to the average reader that

there are dark places in the lineage during the period when our ancestor

had not yet developed a spinal column--when, in other words, he had not

attained the dignity of the lowest fish. Neither, perhaps, need we

mourn greatly that the exact branch by which our reptilian or amphibian

non-mammalian ancestor became the first and most primitive of mammals is

still hidden in unexplored recesses of early strata. The most patrician

monarch of to-day would not be greatly disturbed as to just who were his

ancestors of the days of the cave-dweller. It is when we come a little

nearer home that the question begins to take on its seemingly personal

significance. Questions of grandparents and great-grandparents concern

the patrician very closely. And so all along, the question that has

interested the average casual investigator of the Darwinian theory

has been the question as to man's immediate ancestor--the parents and

grandparents of our race, so to speak. Hence the linking of the word

"monkey" with the phrase "Darwinian theory" in the popular mind; and

hence, also, the interpretation of the phrase "missing link" in relation

to man's ancestry, as applying only to our ancestor and not to any other

of the gaps in the genealogical chain.

What, then, is the present status of Haeckel's genealogical tree

regarding man's most direct ancestor? Prom what non-human parent did the

human race directly spring? That is a question that has proved itself of

lasting, vital human interest. It is a question that long was answered

only with an hypothesis, but which Professor Haeckel to-day professes

to be able to answer with a decisive and affirmative citation not of

theories but of facts. In a word, it is claimed that man's immediate

ancestor is now actually upon record, that the much-heralded "missing

link" is missing no longer. The principal single document, so to

speak, on which this claim is based consists of the now famous skull and

thigh-bone which the Dutch surgeon, Dr. Eugene Dubois, discovered in the

year 1891 in the tertiary strata of the island of Java. Tertiary strata,

it should be explained, had never hitherto yielded any fossils bordering

on the human type, but this now famous skeleton was unmistakably akin

to the human. The thigh in particular, taken by itself, would have

been pronounced by any competent anatomist to be of human origin.

Unquestionably the individual who bore it had been accustomed to take

an erect attitude in walking. And yet the skull was far inferior in size

and shape to that of any existing tribe of man--was, indeed, rather of

a simian type, though, on the other hand, of about twice the capacity

of any existing ape. In a word, it seemed clear that the creature whose

part skeleton had been found by Dr. Dubois was of a type intermediate

between the lowest existing man and the highest existing man-apes. It

was, in short, the actual prototype of that hypothetical creature which

Haeckel, in his genealogical tree, had christened _pithecanthropus_, the

ape-man. As such it was christened _Pithecanthropus erectus_, the erect

ape-man.

Now the discovery of this remarkable form did not make Professor Haeckel

any more certain that some such form had existed than he was thirty

years before when he christened a hypothetical subject with the title

now taken by a tangible claimant. But, after all, there is something

very taking about a prophecy fulfilled, and so the appearance of

_Pithecanthropus erectus_ created no small sensation in the zoological

world. He was hailed by Haeckel and his followers as the veritable

"missing link," and as such gained immediate notoriety. But, on the

other hand, a reactionary party at once attacked him with the most

bitter animadversions, denouncing him as no true ancestor of man with

a bitterness that is hard to understand, considering that the origin of

man from _some_ lower form has long ceased to be matter of controversy.

"_Pithecanthropus_ is at least half an ape," they cried, with the clear

implication of "anything but an ape for an ancestor!"

I confess I have always found it hard to understand just why this

peculiar aversion should always be held against the unoffending ape

tribe. Why it would not be quite as satisfactory to find one's ancestor

in an ape as in the alternative lines of, for example, the cow, or the

hippopotamus, or the whale, or the dog has always been a mystery. Yet

the fact of this prejudice holds. Probably we dislike the ape because

of the very patency of his human affinities. The poor relation is

objectionable not so much because he is poor as because he is a

relation. So, perhaps, it is not the apeness, so to speak, of the ape

that is objectionable, but rather the human-ness. In any event, the

aversion has been matter of common notoriety ever since the Darwinian

theory became fully accepted; it showed itself now with renewed force

against poor _pithecanthropus_. A half-score of objections were launched

against him. It is needless to rehearse them now, since they were all

met valiantly, and the final verdict saw the new-comer triumphantly

ensconced in man's ancestral halls as the oldest sojourner there who

has any title to be spoken of as "human." He is only half human, to be

sure--a veritable ape-man, as his name implies--but exactly therein lies

his altogether unique distinction. He is the embodiment of that "missing

link" whose nonappearance had hitherto given so much comfort to the

sceptical.

Perhaps some crumbs of comfort may be found by the reactionists in the

fact that it is not held by Professor Haeckel, or by any other competent

authority, that the link which _pithecanthropus_ supplies welds man

directly with any existing man-ape--with gorilla, chimpanzee, or orang.

It is held that these highest existing apes are side branches, so

to say, of the ancestral tree, who developed, in their several ways,

contemporaneously with our direct ancestors, but are not themselves

directly of the royal line. The existing ape that has clung closest to

the direct ancestral type of our own race, it appears, is the gibbon--a

creature far less objectionable in that rôle because of the very paucity

of his human characteristics, as revealed to the casual observer.

Gibbon-like fossil apes are known, in strata representing a time some

millions of years antecedent to the epoch of _pithecanthropus_

even, which are held to be directly of the royal line through which

_pithecanthropus_, and the hypothetical _Homo stupidus_, and the known

_Homo neanderthalensis_, and, lastly, proud _Homo sapiens_ himself have

descended. Thus Professor Haeckel is able to make the affirmation, as he

did recently before the International Zoological Congress in Cambridge,

that man's line of descent is now clearly traced, from a stage back in

the Eocene time when our ancestor was not yet more than half arrived to

the ape's estate, down to the time of true human development. "There no

longer exists," he says, "a 'missing link.' The phyletic continuity

of the primate stem, from the oldest lemurs down to man himself, is an

historical fact."

It should, perhaps, be added that the force of this rather startling

conclusion rests by no means exclusively upon the finding of

_pithecanthropus_ and the other fossils, nor indeed upon any

paleontological evidence whatever. These, of course, furnish data of

a very tangible and convincing kind; but the evidence in its totality

includes also a host of data from the realms of embryology and

comparative anatomy--data which, as already suggested, enabled Professor

Haeckel to predicate the existence of _pithecanthropus_ long in advance

of his actual discovery. Whether the more remote gaps in the chain of

man's ancestry will be bridged in a manner similarly in accord with

Professor Haeckel's predications, it remains for future discoveries

of zoologist and paleontologist to determine. In any event, the recent

findings have added an increment of glory to that philosophical zoology

of which Professor Haeckel is the greatest living exponent.

This tracing of genealogies is doubtless the most spectacular feature of

the new zoology, yet it must be clear that the establishment of lines

of evolution is at best merely a preparation for the all-important

question, Why have these creatures, man included, evolved at all? That

question goes to the heart of the new zoological philosophy. A partial

answer was, of course, given by Darwin in his great doctrine of natural

selection. But this doctrine, while explaining the preservation of

favorable variations, made no attempt to account for the variations

themselves. Professor Haeckel's contribution to the subject consisted in

the revival of the doctrine of Lamarck, that individual variations, in

response to environmental influences, are transmitted to the offspring,

and thus furnish the material upon which, applying Darwin's principle,

evolution may proceed. This Lamarck-Haeckel doctrine was under a cloud

for a recent decade, during the brief passing of the Weismannian myth,

but it has now emerged, and stands as the one recognized factor in the

origin of those variations whose cumulative preservation through natural

selection has resulted in the evolution of organic forms.

But may there not be other factors, as yet unrecognized, that supplement

the Lamarckian and Darwinian principles in bringing about this

marvellous evolution of beings? That, it would seem, is the most vital

question that the philosophical zoology of our generation must hand on

to the twentieth century. For today not even Professor Haeckel himself

can give it answer.

VII. SOME MEDICAL LABORATORIES AND MEDICAL PROBLEMS

THE PASTEUR INSTITUTE

THE national egotism that characterizes the French mind is not without

its compensations. It leads, for example, to the tangible recognition

of the merits of the great men of the nation and to the promulgation

of their names in many public ways. Thus it would be hard to mention a

truly distinguished Frenchman of the older generations whose name has

not been given to a street in Paris. Of the men of science thus

honored, one recalls off-hand the names of Buffon, Cuvier, Geoffroy

Saint-Hilaire, Pinel, Esquirol, Lamarck, Laplace, Lavoisier, Arago,

Claude Bernard, Broca--indeed, one could readily extend the list

to tiresome dimensions. Moreover, it is a list that is periodically

increased by the addition of new names, as occasion offers, for the

Parisian authorities never hesitate to rechristen a street or a portion

of a street, regardless of former associations.

One of the most recent additions to this roll of fame is the name of

Pasteur. The boulevard that bears that famous name is situated in a

somewhat out-of-the-way corner of the city, though to reach it one has

but to traverse the relatively short course of the Avenue de Breteuil

from so central a position as the tomb of Napoleon. The Boulevard

Pasteur itself is a not long but very spacious thoroughfare, which

will some day be very beautiful, when the character of its environing

buildings has somewhat changed and its quadruple rows of trees have had

time for development. At present its chief distinction, in the eyes

of most observers, would probably be found in the fact that it is the

location of the famous _fête forain_ at one of the annually recurring

stages of the endless itinerary of that noted function. During the

period of this distinction, which falls in the month of May, the

boulevard becomes transformed into a veritable Coney Island of

merry-go-rounds, shooting-galleries, ginger-bread booths, and clap-trap

side-shows, to the endless delight of throngs of pleasure-seekers. There

is no sight in all Paris worthier inspection for the foreigner than the

Boulevard Pasteur offers at this season, for one gains a deep insight

into the psychology of a people through observation of the infantile

delight with which the adult population here throws itself into the

spirit of amusements which with other nations are for the most part

reserved for school-children. Only a race either in childhood or

senescence, it would seem, could thus give itself over with undisguised

delight to the enchantments of wooden horses, cattle, cats, and pigs; to

the catching of wooden fish with hooks; to the shooting at targets that

one could almost touch with the gun-muzzle, and to the grave observation

of sideshow performances that would excite the risibilities of the most

unsophisticated audience that could be found in the Mississippi Valley.

As we move among this light-hearted and lightheaded throng we shall

scarcely escape a feeling of good-humored contempt for what seems an

inferior race. It will be wholesome, therefore, for us to turn aside

from the boulevard into the Rue Dotot, which leads from it near its

centre, and walk a few hundred yards away from the pleasure-seekers,

where an evidence of a quite different and a no less characteristic

phase of the national psychology will be before us. For here, within

easy sound of the jangling discords of the organs that keep time for the

march of the _cheveaux de bois_, rises up a building that is in a sense

the monument of a man who was brother in blood and in sentiment to the

revellers we have just left in the boulevard, yet whose career stamped

him as one of the greatest men of genius of any race or any time. That

man was Louis Pasteur. The building before us is the famous institute

that bears his name.

In itself this building is a simple and unimposing structure, yet of

pleasing contour. It is as well placed as the surroundings permit, on a

grassed terrace, a little back from the street, where a high iron fence

guards it and gives it a degree of seclusion. There are other buildings

visible in the rear, which, as one learns on entering, are laboratories

and the like, where the rabbits and guinea-pigs and dogs that are so

essential to the work of the laboratory are kept. On the terrace

in front is a bronze statue of a boy struggling with a rabid dog--a

reminder of the particular labor of the master-worker which led directly

to the foundation of the institution. It will be remembered that it

was primarily to give Pasteur a wider opportunity to apply his newly

discovered treatment for the prevention of rabies that the subscription

was undertaken which led finally to the erection of the buildings before

us and brought the Pasteur Institute in its present form into being.

Of the other aims and objects of the institution I shall speak more at

length in a moment.

I have just said that the building before us is in effect the monument

of the great savant. This is true in a somewhat more literal sense than

might be supposed, for the body of Pasteur rests in a crypt at its base.

The personal labors of the great discoverer were practically ended at

the time when the institute was opened in 1888, on which occasion,

as will be remembered, the scientific representatives of all nations

gathered in Paris to do honor to the greatest Frenchman of his

generation. He was spared to the world, however, for seven years more,

during which time he fully organized the work of the institution along

the lines it has since followed, and was, of course, the animating

spirit of all the labors undertaken there by his devoted students and

assistants. He is the animating spirit of the institution still, and it

is fitting that his body should rest in the worthy mausoleum within the

walls of that building whose erection was the tangible culmination

of his life labors. The sarcophagus is a shrine within this temple of

science which will serve to stimulate generations of workers here to

walk worthily in the footsteps of the great founder of the institution.

For he must be an unimaginative person indeed who, passing beneath that

arch bearing the simple inscription "Ici Repose Pasteur," could descend

into the simple but impressive mausoleum and stand beside the massive

granite sarcophagus without feeling the same kind of mental uplift which

comes from contact with a great and noble personality. The pretentious

tomb of Galileo in the nave of Santa Croce at Florence, and the crowded

resting-place of Newton and Darwin in Westminster Abbey, have no such

impressiveness as this solitary vault where rests the body of Pasteur,

isolated in death as the mightier spirits must always be in life.

AIMS AND OBJECTS OF THE PASTEUR INSTITUTE

If one chances to come to the institute in the later hours of the

morning he will perhaps be surprised to find a motley company of men,

women, and children, apparently of many nationalities and from varied

walks of life, gathered about one of the entrances or sauntering near

by. These are the most direct beneficiaries of the institution, the

unfortunate victims of the bites of rabid dogs, who have come here to

take the treatment which alone can give them immunity from the terrible

consequences of that mishap. Rabies, or hydrophobia as it is more

commonly termed with us, is well known to be an absolutely fatal malady,

there being no case on record of recovery from the disease once fully

established. Even the treatment which Pasteur developed and which is

here carried out cannot avail to save the victim in whom the active

symptoms of the malady are actually present. But, fortunately, the

disease is peculiarly slow in its onset, sometimes not manifesting

itself for weeks or months after the inoculation; and this delay, which

formerly was to the patient a period of fearful doubt and anxiety, now

suffices, happily, for the application of the protective inoculations

which enable the person otherwise doomed to resist the poison and go

unscathed. Thus it is that the persons who gather here each day to the

number of fifty, or even one hundred, have the appearance of and the

feelings of average health, though a large proportion of them bear in

their systems, on arrival, the germs of a disease that would bring them

speedily to a terrible end were it not that the genius of Pasteur had

found a way to give them immunity. The number of persons who have been

given the anti-rabic treatment here is more than twenty-five thousand.

To have given safety to such an army of unfortunates is, indeed, enough

merit for any single institution; but it must not be supposed that this

record is by any manner of means the full measure of the benefits which

the Institut Pasteur has conferred upon humanity. In point of fact, the

preparation and use of the anti-rabic serum is only one of many aims

of the institution, whose full scope is as wide as the entire domain of

contagious diseases. Pasteur's personal discoveries had demonstrated

the relation of certain lower organisms, notably the bacteria, to the

contagious diseases, and had shown the possibility of giving immunity

from certain of these diseases through the use of cultures of the

noxious bacteria themselves. He believed that these methods could be

extended and developed until all the contagious diseases, which hitherto

have accounted for so startling a proportion of all deaths, were brought

within the control of medical science. His deepest thought in founding

the institute was to supply a tangible seat of operations for this

attempted conquest, where the brilliant assistants he had gathered about

him, and their successors in turn, might take a share in this great

struggle, unhampered by the material drawbacks which so often confront

the would-be worker in science.

He desired also that the institution should be a centre of education

along the lines of its work, adding thus an indirect influence to the

score of its direct achievements. In both these regards the institution

has been and continues to be worthy of its founder. The Pasteur

Institute is in effect a school of bacteriology, where each of the

professors is at once a teacher and a brilliant investigator. The chief

courses of instruction consist of two series each year of lectures and

laboratory demonstrations on topics within the field of bacteriology.

These courses, at which all the regular staff of the institution assist

more or less, are open to physicians and other competent students

regardless of nationality, and they suffice to inculcate the principles

of bacteriology to a large band of seekers each year.

But more important, perhaps, than this form of educational influence is

the impetus given by the institute to the researches of a small, select

band of investigators who have taken up bacteriology for a life work,

and who come here to perfect themselves in the final niceties of the

technique of a most difficult profession. Thus such men as Calmette,

the discoverer of the serum treatment of serpent-poisoning, and Yersin,

famous for his researches in the prevention and cure of cholera by

inoculation, are "graduates" of the Pasteur Institute. Indeed, almost

all the chief laborers in this field in the world to-day, including the

directors of practically all the daughter institutes bearing the same

name that are now scattered all over the world, have had at least a

share of their training in the mother institute here in Paris.

Of the work of the men who form the regular staff of the Pasteur

Institute only a few words need be said here. Doctors Roux, Grancher,

Metchnikoff, and Chamberland all had the privilege of sharing Pasteur's

labors during the later years of the master's life, and each of them is

a worthy follower of the beloved leader and at the same time a brilliant

original investigator.*1* Roux is known everywhere in connection with

the serum treatment of diphtheria, which he was so largely instrumental

in developing. Grancher directs the anti-rabic department and allied

fields. Metchnikoff, a Russian by birth and Parisian by adoption, is

famous as the author of the theory that the white blood-corpuscles of

the blood are the efficient agents in combating bacteria. Chamberland

directs the field of practical bacteriology in its applications to

hygiene, including the department in which protective serums are

developed for the prevention of various diseases of domesticated

animals, notably swine fever and anthrax. About one million sheep and

half as many cattle are annually given immunity from anthrax by the

serum here produced.

Of the patient and unremitting toil demanded of the investigator in

this realm of the infinitely little; of the skill in manipulation, the

fertility of resource, the scrupulous exactness of experiment that

are absolutely prerequisite to success; of the dangers that attend

investigations which deal with noxious germs, every one who knows

anything of the subject has some conception, but those alone can have

full comprehension who have themselves attempted to follow the devious

and delicate pathways of bacteriology. But the goals to which these

pathways lead have a tangibility that give them a vital interest for all

the world. The hopes and expectations of bacteriology halt at nothing

short of the ultimate extirpation of contagious diseases. The way to

that goal is long and hard, yet in time it will be made passable. And

in our generation there is no company of men who are doing more

towards that end than the staff of that most famous of bacteriological

laboratories the Pasteur Institute.

THE VIRCHOW INSTITUTE OF PATHOLOGY

Even were the contagious diseases well in hand, there would still

remain a sufficient coterie of maladies whose origin is not due to the

influence of living germs. There are, for example, many diseases of the

digestive, nutritive, and excretory systems, of the heart and arteries,

of the brain and nerves, and various less clearly localized abnormal

conditions, that owe their origin to inherent defects of the

organism, or to various indiscretions of food or drink, to unhygienic

surroundings, to material injuries, or to other forms of environmental

stress quite dissociated from the action of bacteria. It is true that

one would need to use extreme care nowadays in defining more exactly the

diseases that thus lie without the field of the bacteriologist, as that

prying individual seems prone to claim almost everything within sight,

and to justify his claim with the microscope; but after that instrument

has done its best or worst, there will still remain a fair contingent

of maladies that cannot fairly be brought within the domain of the

ever-present "germ." On the other hand, all germ diseases have of course

their particular effects upon the system, bringing their results within

the scope of the pathologist. Thus while the bacteriologist has no

concern directly with any disease that is not of bacterial origin, the

pathologist has a direct interest in every form of disease whatever;

in other words, bacteriology, properly considered, is only a special

department of pathology, just as pathology itself is only a special

department of general medicine.

Whichever way one turns in science, subjects are always found thus

dovetailing into one another and refusing to be sharply outlined.

Nevertheless, here as elsewhere, there are theoretical bounds that

suffice for purposes of definition, if not very rigidly lived up to in

practice; and we are justified in thinking of the pathologist (perhaps

I should say the pathological anatomist) as the investigator of disease

who is directly concerned with effects rather than with causes, who aims

directly at the diseased tissue itself and reasons only secondarily

to the causes. His problem is: given a certain disease (if I may be

permitted this personified form of expression), to find what tissues of

the body are changed by it from the normal and in what manner changed.

It requires but a moment's reflection to make it clear that a certain

crude insight into the solution of this problem, as regards all common

diseases, must have been the common knowledge of medical men since

the earliest times. Thus not even medical knowledge was needed to

demonstrate that the tissues of an in: flamed part become red and

swollen; and numerous other changes of diseased tissues are almost

equally patent. But this species of knowledge, based on microscopic

inspection, was very vague and untrustworthy, and it was only after the

advent of the perfected microscope, some three-quarters of a century

ago, that pathological anatomy began to have any proper claim to

scientific rank. Indeed, it was not until about the year 1865 that the

real clew was discovered which gave the same impetus to pathology that

the demonstration of the germ theory of disease gave at about the same

time to etiology, or the study of causes of disease. This clew consisted

of the final demonstration that all organic action is in the last resort

a question of cellular activities, and, specifically, that all abnormal

changes in any tissues of the body, due to whatever disease, can consist

of nothing more than the destruction, or the proliferation, or the

alteration of the cells that compose that tissue.

That seems a simple enough proposition nowadays, but it was at once

revolutionary and inspiring in the day of its original enunciation some

forty years ago. The man who had made the discovery was a young German

physician, professor in the University of Freiburg, by name Rudolph

Virchow. The discovery made him famous, and from that day to this the

name of Virchow has held somewhat the same position in the world

of pathology that the name of Pasteur occupied in the realm of

bacteriology. Virchow was called presently to a professorship in the

University of Berlin. In connection with this chair he established his

famous Institute of Pathology, which has been the Mecca of all students

of pathology ever since. He did a host of other notable things as well,

among others, entering the field of politics, and becoming a recognized

leader there no less than in science. Indeed, it seemed during the later

decades of his life as if one encountered Virchow in whatever direction

one turned in Berlin, and one feels that it was not without reason that

his compatriots spoke of him as "the man who knows everything." To the

end he retained all the alertness of intellect and the energy of body

that had made him what he was. One found him at an early hour in the

morning attending to the routine of his hospital duties, his lectures,

and clinical demonstrations. These finished, he rushed off, perhaps

to his parliamentary duties; thence to a meeting of the Academy of

Sciences, or to preside at the Academy of Medicine or at some other

scientific gathering. And in intervals of these diversified pursuits he

was besieged ever by a host of private callers, who sought his opinion,

his advice, his influence in some matter of practical politics, of

statecraft, or of science, or who, perhaps, had merely come the length

of the continent that they might grasp the hand of the "father of

pathology."

In whatever capacity one sought him out, provided the seeking were not

too presumptuous, one was sure to find the great savant approachable,

courteous, even cordial. A man of multifarious affairs, he impressed

one as having abundance of time for them all, and to spare. There is a

leisureliness about the seeming habit of existence on the Continent that

does not pertain in America, and one felt the flavor of it quite as much

in the presence of this great worker as among those people who from

our stand-point seem never really to work at all. This is to a certain

extent explained if one visited Virchow in his home, and found to his

astonishment that the world-renowned physician, statesman, pathologist,

anthropologist was domiciled in a little apartment of the most modest

equipment, up two flights, in a house of most unpretentious character.

Everything was entirely respectable, altogether comfortable, to be sure;

but it was a grade of living which a man of corresponding position in

America could not hold to without finding himself quite out of step with

his confrères and the subject of endless comment. But in this city

of universal apartment-house occupancy and relatively low average of

display in living it is quite otherwise. Virchow lived on the same

plane, generally speaking, with the other scientists of Europe; it is

only from the American standpoint that there is any seeming disparity

between his fame and his material station in life; nor do I claim this

as a merit of the American stand-point.

Be that as it may, however, our present concern lies not with these

matters, but with Virchow the pathologist and teacher. To see the

great scientist at his best in this rôle, it was necessary to visit the

Institute of Pathology on a Thursday morning at the hour of nine. On

the morning of our visit we found the students already assembled and

gathered in clusters all about the room, examining specimens of morbid

anatomy, under guidance of various laboratory assistants. This was

to give them a general familiarity with the appearances of the

disease-products that would be described to them in the ensuing lecture.

But what is most striking about the room was the very unique method of

arrangement of the desk or table on which the specimens rested. It

was virtually a long-drawn-out series of desks winding back and forth

throughout the entire room, but all united into one, so that a specimen

passed along the table from end to end will make a zigzag tour of the

room, passing finally before each person in the entire audience. To

facilitate such transit, there was a little iron railway all along the

centre of the table, with miniature turn-tables at the corners, along

which microscopes, with adjusted specimens for examination, might be

conveyed without danger of maladjustment or injury. This may seem a

small detail, but it is really an important auxiliary in the teaching

by demonstration with specimens for which this room was peculiarly

intended. The ordinary lectures of Professor Virchow were held in a

neighboring amphitheatre of conventional type.

Of a sudden there was a hush in the hum of voices, as a little, thin,

frail-seeming man entered and stepped briskly to the front of the

room and upon the low platform before the blackboard in the corner. A

moment's pause for the students to take their places, and the lecturer,

who of course was Virchow himself, began, in a clear, conversational

voice, to discourse on the topic of the day, which chanced to be the

formation of clots in blood-vessels. There was no particular attempt at

oratory; rather the lecturer proceeded as if talking man to man, with

no thought but to make his meaning perfectly clear. He began at once

putting specimens in circulation, as supplied on his demand by his

assistants from a rather grewsome-looking collection before him. Now

he paused to chaff the assistant who was making the labels, poking

good-humored jokes at his awkwardness, but with no trace of sting. Again

he became animated, his voice raised a little, his speech more vehement,

as he advanced his own views on some contested theory or refuted the

objections that some opponent had urged against him, always, however,

with a smile lurking about his eyes or openly showing on his lips.

Constantly the lecturer turned to the blackboard to illustrate with

colored, crayons such points of his discourse as the actual specimens in

circulation might leave obscure. Everything must be made plain to every

hearer or he would not be satisfied. One can but contrast such teaching

as this with the lectures of the average German professor, who seems not

to concern himself in the least as to whether anything is understood by

any one. But Virchow had the spirit of the true teacher. He had the air

of loving his task, old story as it was to him. Most of his auditors

were mere students, yet he appealed to them as earnestly as if they

were associates and equals. He seemed to try to put himself on their

level--to make his thought near to them. Physically he was near to them

as he talked, the platform on which he stood being but a few inches

in height, and such physical nearness conduces to a familiarity of

discourse that is best fitted for placing lecturer and hearers _en

rapport_. All in all, appealing as it does almost equally to ear and

eye, it is a type of what a lecturer should be. Not a student there but

went away with an added fund of information, which is far more than can

be said of most of the lectures in a German university.

Needless to say, there are other departments to the Institute of

Pathology. There are collections of beautifully preserved specimens for

examination; rooms for practical experimentation in all phases of the

subject, the chemical side included; but these are not very different

from the similar departments of similar institutions everywhere. What

was unique and characteristic about this institution was the personality

of the director. Now he is gone, but his influence will not soon be

forgotten. The pupils of a great teacher are sure to carry forward the

work somewhat in the spirit of the master for at least a generation.

THE BERLIN INSTITUTE OP HYGIENE

I purposely refrain from entering into any details as to the character

of the technical work done at the Virchow Institute, because the subject

of pathology, despite its directly practical bearings, is in itself

necessarily somewhat removed from the knowledge of the general reader.

One cannot well understand the details of changes in tissues under

abnormal conditions unless one first understands the normal conditions

of the tissues themselves, and such knowledge is reserved for the

special students of anatomy. For the nonprofessional observer the

interest of the Virchow Institute must lie in its general scope rather

than in the details of the subjects there brought under investigation,

which latter have, indeed, of necessity, a somewhat grewsome character

despite the beneficent results that spring from them. It is quite

otherwise, however, with the work of the allied institution of which I

now come to speak. The Institute of Hygiene deals with topics not very

remote from those studied in the Virchow Institute, part of its work,

indeed, falling clearly within the scope of pathology; but it differs in

being clearly comprehensible to the general public and of immediate

and tangible interest from the most strictly utilitarian stand-point,

hygiene being, in effect, the tangible link between the more abstract

medical sciences and the affairs of every-day life.

The Institute of Hygiene has also the interest that always attaches to

association with a famous name, for it was here that Professor Koch made

the greater part of those investigations which made his name the best

known, next to that of Pasteur, of any in the field of bacteriology.

In particular, the researches on the cholera germ, and those even more

widely heralded researches that led to the discovery of the bacillus of

tuberculosis, and the development of the remedy tuberculin, of which

so much was at first expected, were made by Professor Koch in the

laboratories of the antiquated building which was then and is still

the seat of the Institute of Hygiene. More recently Professor Koch has

severed his connection with the institution after presiding over it for

many years, having now a semi-private laboratory just across from the

Virchow Institute, in connection with the Charité Hospital; but one

still thinks of the Institute of Hygiene as peculiarly the "Koch

Institute" without injustice, so fully does its work follow the lines

laid out for it by the great leader.

But however much the stamp of any individual personality may rest upon

the institute, it is officially a department of the university, just as

is the Virchow Institute. Like the latter, also, its local habitation

is an antiquated building, strangely at variance, according to American

ideas, with its reputation, though by no means noteworthy in this regard

in the case of a German institution. It is situated in a part of the

city distant from any other department of the university, and there is

nothing about it exteriorly to distinguish it from other houses of the

solid block in which it stands. Interiorly, it reminds one rather of a

converted dwelling than a laboratory proper. Its rooms are well

enough adapted to their purpose, but they give one the impression of

a makeshift. The smallest American college would be ill-satisfied with

such an equipment for any department of its work. Yet in these dingy

quarters has been accomplished some of the best work in the new science

of bacteriology that our century will have to boast.

The actual equipment of the bacteriological laboratory here is not,

indeed, quite as meagre as it seems at first, there being numerous

rooms, scattered here and there, which in the aggregate give opportunity

for work to a large number of investigators, though no single room makes

an impressive appearance. There is one room, however, large enough to

give audience to a considerable class, and here lectures were given by

Professor Koch and continue to be given by his successors to the special

students of bacteriology who come from all over the world, as well as to

the university students who take the course as a part of their regular

medical curriculum. In regard to this feature of its work, the Institute

of Hygiene differs in no essential respect from the Pasteur Institute

and other laboratories of bacteriology. The same general routine of work

pertains: the patient cultivation of the minute organisms in various

mediums, their careful staining by special processes, and their

investigation under the microscope mark the work of the bacteriologist

everywhere. Many details of the special methods of culture or treatment

originated here with Professor Koch, but such matters are never kept

secret in science, so one may see them practised quite as generally

and as efficiently in other laboratories as in this one. Indeed, it may

frankly be admitted that, aside from its historical associations with

the pioneer work in bacteriology, which will always make it memorable,

there is nothing about the bacteriological laboratory here to give it

distinction over hundreds of similar ones elsewhere; while in point of

technical equipment, as already noted, it is remarkable rather for what

it lacks than for what it presents.

The department of bacteriology, however, is only one of several

important features of the institute. One has but to ascend another

flight of stairs to pass out of the sphere of the microbe and enter a

department where attention is directed to quite another field. We have

now come to what may be considered the laboratory of hygiene proper,

since here the investigations have to do directly with the functionings

of the human body in their relations to the every-day environment.

Here again one is struck with the meagre equipment with which important

results may be attained by patient and skilled investigators. In only

one room does one find a really elaborate piece of apparatus. This

exceptional mechanism consists essentially of a cabinet large enough to

give comfortable lodgment to a human subject--a cabinet with walls of

peculiar structure, partly of glass, and connected by various pipes with

sundry mysterious-seeming retorts. This single apparatus, however, is

susceptible of being employed for the investigation of an almost endless

variety of questions pertaining to the functionings of the human body

considered as a working mechanism.

Thus, for example, a human subject to be experimented upon may remain

for an indefinite period within this cabinet, occupied in various ways,

taking physical exercise, reading, engaged in creative mental labor,

or sleeping. Meantime, air is supplied for respiration in measured

quantities, and of a precisely determined composition, as regards

chemical impurities, moisture, and temperature. The air after passing

through the chamber being again analyzed, the exact constituents added

to it as waste products of the human machine in action under varying

conditions are determined. It will readily be seen that by indefinitely

varying the conditions of such experiments a great variety of data

may be secured as to the exact physiological accompaniments of various

bodily and mental activities. Such data are of manifest importance to

the physiologist and pathologist on the one hand, while at the same

time having a direct bearing on such eminently practical topics as the

construction of shops, auditoriums, and dwellings in reference to light,

heat, and ventilation. It remains only for practical architecture to

take advantage of the unequivocal data thus placed at its disposal--an

opportunity of which practical architecture, in Germany as elsewhere on

the Continent, has hitherto been very slow to avail itself.

THE MUSEUM OF HYGIENE

The practical lessons thus given in the laboratory are supplemented in

an even more tangible manner, because in a way more accessible to

the public, in another department of the institution which occupies a

contiguous building, and is known as the Museum of Hygiene. This, unlike

the other departments of the institute, is open to the general public

on certain days of each week, and it offers a variety of exhibits of

distinctly novel character and of high educational value. The general

character of the exhibits may be inferred from the name, but perhaps the

scope is even wider than might be expected. In a word, it may be said

that scarcely anything having to do with practical hygiene has been

overlooked. Thus one finds here numberless models of dwelling-houses,

showing details of lighting, heating, and ventilation; models not

merely of individual dwellings, but also of school-buildings, hospitals,

asylums, and even prisons. Sometimes the models represent merely

ideal buildings, but more generally they reproduce in miniature actual

habitations. In the case of the public buildings, the model

usually includes not merely the structures themselves but the

surroundings--lawns, drives, trees, out-buildings--so that one can get a

very good idea of the more important hospitals, asylums, and prisons of

Germany by making a tour of the Museum of Hygiene. Regarding the details

of structure, one can actually gain a fuller knowledge in many cases

than he could obtain by actual visits to the original institutions

themselves.

The same thing is true of various other features of the subjects

represented. Thus there is a very elaborate model here exhibited of the

famous Berlin system of sewage-disposal. As is well known, the essential

features of this system consist of the drainage of sewage into local

reservoirs, from which it is forced by pumps, natural drainage not

sufficing, to distant fields, where it is distributed through tile pipes

laid in a network about a yard beneath the surface of the soil. The

fields themselves, thus rendered fertile by the waste products of the

city, are cultivated, and yield a rich harvest of vegetables and grains

of every variety suitable to the climate. The visitor to this field

sees only rich farms and market-gardens under ordinary process of

cultivation. The system of pipes by which the land is fertilized is

as fully hidden from his view as are, for example, the tributary

sewage-pipes beneath the city pavements. The average visitor to Berlin

knows nothing, of course, about one or the other, and goes away, as he

came, ignorant of the important fact that Berlin has reached a better

solution of the great sewage problem than has been attained by any

other large city. Such, at least, is likely to be the case unless the

sight-seer chance to pay a visit to the Museum of Hygiene, in which

case a few minutes' inspection of the model there will make the matter

entirely clear to him. It is to be regretted that the authorities

of other large cities do not make special visits to Berlin for this

purpose; though it should be added that some of them have done so, and

that the Berlin system of "canalization" has been adopted in various

places in America. But many others might wisely follow their example,

notably the Parisians, whose sewerage system, despite the boasted

exhibition canal-sewer, is, like so many other things Parisian, of the

most primitive character and a reproach to present-day civilization.

It may be added that there are plenty of things exhibited in this museum

which the Germans themselves might study to advantage, for it must be

understood that the other hygienic conditions pertaining to Berlin are

by no means all on a par with the high modern standard of the sewerage

system. In the matter of ventilation, for example, one may find

admirable models in the museum, showing just how the dwelling and shop

and school-room should make provision for a proper supply of pure air

for their occupants. But if one goes out from the museum and searches in

the actual dwelling or shop or school-room for the counterparts of

these models, one will be sorely puzzled where to find them. The general

impression which a casual inspection will leave in his mind is that the

word ventilation must be as meaningless to the German mind as it is, for

example, to the mind of a Frenchman or an Italian. This probably is not

quite just, since the German has at least reached the stage of having

museum models of ventilated houses, thus proving that the idea does

exist, even though latent, in his mental equipment, whereas the other

continental nationalities seem not to have reached even this incipient

stage of progress. All over Europe the people fear a current of air as

if veritable miasm must lurk in it. They seem quite oblivious to any

systematic necessity for replenishing the oxygen supply among large

assemblies, as any one can testify who has, for example, visited their

theatres or schools. And as to the private dwellings, after making

them as nearly air-tight as practicable, they endeavor to preserve the

_status quo_ as regards air supply seemingly from season to season. They

even seem to have passed beyond a mere negative regard for the subject

of fresh air, inasmuch as they will bravely assure you that to sleep

in a room with an open window will surely subject you to the penalty of

inflamed eyes.

In a country like France, where the open fireplace is the usual means

employed to modify the temperature (I will not say warm the room),

the dwellings do of necessity get a certain amount of ventilation,

particularly since the windows are not usually of the best construction.

But the German, with his nearly air-tight double windows and his even

more nearly sealed tile stove, spends the winter in an atmosphere

suggestive of the descriptions that arctic travellers give us of the

air in the hut of an Eskimo. It is clear, then, that the models in the

Museum of Hygiene have thus far failed of the proselyting purpose

for which they were presumably intended. How it has chanced that the

inhabitants of the country maintain so high an average of robust health

after this open defiance is a subject which the physiological department

of the Institute of Hygiene might well investigate.

Even though the implied precepts of the Museum of Hygiene are so largely

disregarded, however, it must be admitted that the existence of the

museum is a hopeful sign. It is a valuable educational institution,

and if its salutary lessons are but slowly accepted by the people, they

cannot be altogether without effect. At least the museum proves that

there are leaders in science here who have got beyond the range of

eighteenth-century thought in matters of practical living, and the

sign is hopeful for the future, though its promise will perhaps not be

fulfilled in our generation.

VII. SOME UNSOLVED SCIENTIFIC PROBLEMS

IN recent chapters we have witnessed a marvellous development in many

branches of pure science. In viewing so wonderfully diversified a field,

it has of course been impossible to dwell upon details, or even to

glance at every minor discovery. At best one could but summarize the

broad sweep of progress somewhat as a battle might be described by a

distant eye-witness, telling of the general direction of action, of

the movements of large masses, the names of leaders of brigades and

divisions, but necessarily ignoring the lesser fluctuations of advance

or recession and the individual gallantry of the rank and file. In

particular, interest has centred upon the storming of the various

special strongholds of ignorant or prejudiced opposition, which at last

have been triumphantly occupied by the band of progress. In each case

where such a stronghold has fallen, the victory has been achieved solely

through the destructive agency of newly discovered or newly marshalled

facts--the only weapons which the warrior of science seeks or cares for.

Facts must be marshalled, of course, about the guidon of a hypothesis,

but that guidon can lead on to victory only when the facts themselves

support it. Once planted victoriously on the conquered ramparts the

hypothesis becomes a theory--a generalization of science--marking a

fresh coign of vantage, which can never be successfully assailed unless

by a new host of antagonistic facts. Such generalizations, with the

events leading directly up to them, have chiefly occupied our attention.

But a moment's reflection makes it clear that the battle of science,

thus considered, is ever shifting ground and never ended. Thus at

any given period there are many unsettled skirmishes under way; many

hypotheses are yet only struggling towards the stronghold of theory,

perhaps never to attain it; in many directions the hosts of antagonistic

facts seem so evenly matched that the hazard of war appears uncertain;

or, again, so few facts are available that as yet no attack worthy the

name is possible. Such unsettled controversies as these have, for the

most part, been ignored in our survey of the field. But it would not be

fair to conclude our story without adverting to them, at least in brief;

for some of them have to do with the most comprehensive and important

questions with which science deals, and the aggregate number of facts

involved in these unfinished battles is often great, even though as yet

the marshalling has not led to final victory for any faction. In some

cases, doubtless, the right hypothesis is actually in the field, but its

supremacy not yet conclusively proved--perhaps not to be proved for many

years or decades to come. Some of the chief scientific results of the

nineteenth century have been but the gaining of supremacy for hypotheses

that were mere forlorn hopes, looked on with general contempt, if at

all heeded, when the eighteenth century came to a close--witness the

doctrines of the great age of the earth, of the immateriality of heat,

of the undulatory character of light, of chemical atomicity, of

organic evolution. Contrariwise, the opposite ideas to all of these

had seemingly a safe supremacy until the new facts drove them from the

field. Who shall say, then, what forlorn hope of to-day's science may

not be the conquering host of to-morrow? All that one dare attempt is

to cite the pretensions of a few hypotheses that are struggling over the

still contested ground.

SOLAR AND TELLURIC PROBLEMS

Our sun being only a minor atom of the stellar pebble, solar problems

in general are of course stellar problems also. But there are certain

special questions regarding which we are able to interrogate the sun

because of his proximity, and which have, furthermore, a peculiar

interest for the residents of our little globe because of our dependence

upon this particular star. One of the most far-reaching of these is

as to where the sun gets the heat that he gives off in such

liberal quantities. We have already seen that Dr. Mayer, of

conservation-of-energy fame, was the first to ask this question. As

soon as the doctrine of the persistence and convertibility of energy was

grasped, about the middle of the century, it became clear that this

was one of the most puzzling of questions. It did not at all suffice to

answer that the sun is a ball of fire, for computation showed that, at

the present rate of heat-giving, if the sun were a solid mass of coal,

he would be totally consumed in about five thousand years. As no such

decrease in size as this implies had taken place within historic times,

it was clear that some other explanation must be sought.

Dr. Mayer himself hit upon what seemed a tenable solution at the very

outset. Starting from the observed fact that myriads of tiny meteorites

are hurled into the earth's atmosphere daily, he argued that the sun

must receive these visitants in really enormous quantities--sufficient,

probably, to maintain his temperature at the observed limits. There was

nothing at all unreasonable about this assumption, for the amount of

energy in a swiftly moving body capable of being transformed into heat

if the body be arrested is relatively enormous. Thus it is calculated

that a pound of coal dropped into the sun from the mathematician's

favorite starting-point, infinity, would produce some six thousand times

the heat it could engender if merely burned at the sun's surface. In

other words, if a little over two pounds of material from infinity

were to fall into each square yard of the sun's surface each hour, his

observed heat would be accounted for; whereas almost seven tons per

square yard of stationary fuel would be required each hour to produce

the same effect.

In view of the pelting which our little earth receives, it seemed not

an excessive requisition upon the meteoric supply to suppose that the

requisite amount of matter may fall into the sun, and for a time this

explanation of his incandescence was pretty generally accepted. But soon

astronomers began to make calculations as to the amount of matter which

this assumption added to our solar system, particularly as it aggregated

near the sun in the converging radii, and then it was clear that no such

mass of matter could be there without interfering demonstrably with the

observed course of the interior planets. So another source of the sun's

energy had to be sought. It was found forthwith by that other great

German, Helmholtz, who pointed out that the falling matter through which

heat may be generated might just as well be within the substance of the

sun as without--in other words, that contraction of the sun's heated

body is quite sufficient to account for a long-sustained heat-supply

which the mere burning of any known substance could not approach.

Moreover the amount of matter thus falling towards the sun's centre

being enormous--namely, the total substance of the sun--a relatively

small amount of contraction would be theoretically sufficient to keep

the sun's furnace at par, so to speak.

At first sight this explanation seemed a little puzzling to many laymen

and some experts, for it seemed to imply, as Lord Kelvin pointed out,

that the sun contracts because it is getting cooler, and gains heat

because it contracts. But this feat is not really as paradoxical as it

seems, for it is not implied that there is any real gain of heat in the

sun's mass as a whole, but quite the reverse. All that is sought is

an explanation of a maintenance of heat-giving capacity relatively

unchanged for a long, but not an interminable, period. Indeed,

exactly here comes in the novel and startling feature of. Helmholtz's

calculation. According to Mayer's meteoric hypothesis, there were no

data at hand for any estimate whatever as to the sun's permanency, since

no one could surmise what might be the limits of the meteoric supply.

But Helmholtz's estimate implied an incandescent body cooling--keeping

up a somewhat equable temperature through contraction for a time, but

for a limited time only; destined ultimately to become liquid, solid; to

cool below the temperature of incandescence--to die. Not only so, but

it became possible to calculate the limits of time within which this

culmination would probably occur. It was only necessary to calculate the

total amount of heat which could be generated by the total mass of our

solar system in falling together to the sun's centre from "infinity" to

find the total heat-supply to be drawn upon. Assuming, then, that the

present observed rate of heat-giving has been the average maintained

in the past, a simple division gives the number of years for which the

original supply is adequate. The supply will be exhausted, it will be

observed, when the mass comes into stable equilibrium as a solid body,

no longer subject to contraction, about the sun's centre--such a body,

in short, as our earth is at present.

This calculation was made by Lord Kelvin, Professor Tait, and others,

and the result was one of the most truly dynamitic surprises of the

century. For it transpired that, according to mathematics, the entire

limit of the sun's heat-giving life could not exceed something like

twenty-five millions of years. The publication of that estimate, with

the appearance of authority, brought a veritable storm about the heads

of the physicists. The entire geological and biological worlds were

up in arms in a trice. Two or three generations before, they hurled

brickbats at any one who even hinted that the solar system might be more

than six thousand years old; now they jeered in derision at the attempt

to limit the life-bearing period of our globe to a paltry fifteen or

twenty millions.

The controversy as to solar time thus raised proved one of the most

curious and interesting scientific disputations of the century. The

scene soon shifted from the sun to the earth; for a little reflection

made it clear that the data regarding the sun alone were not

sufficiently definite. Thus Dr. Croll contended that if the parent

bodies of the sun had chanced to be "flying stars" before collision,

a vastly greater supply of heat would have been engendered than if the

matter merely fell together. Again, it could not be overlooked that

a host of meteors are falling into the sun, and that this source of

energy, though not in itself sufficient to account for all the heat in

question, might be sufficient to vitiate utterly any exact calculations.

Yet again, Professor Lockyer called attention to another source of

variation, in the fact that the chemical combination of elements

hitherto existing separately must produce large quantities of heat, it

being even suggested that this source alone might possibly account for

all the present output. On the whole, then, it became clear that the

contraction theory of the sun's heat must itself await the demonstration

of observed shrinkage of the solar disk, as viewed by future generations

of observers, before taking rank as an incontestable theory, and that

computations as to time based solely on this hypothesis must in the mean

time be viewed askance.

But the time controversy having taken root, new methods were naturally

found for testing it. The geologists sought to estimate the period of

time that must have been required for the deposit of the sedimentary

rocks now observed to make up the outer crust of the earth. The amount

of sediment carried through the mouth of a great river furnishes a clew

to the rate of denudation of the area drained by that river. Thus the

studies of Messrs. Humphreys and Abbot, made for a different purpose,

show that the average level of the territory drained by the Mississippi

is being reduced by about one foot in six thousand years. The sediment

is, of course, being piled up out in the Gulf at a proportionate rate.

If, then, this be assumed to be an average rate of denudation and

deposit in the past, and if the total thickness of sedimentary deposits

of past ages were known, a simple calculation would show the age of the

earth's crust since the first continents were formed. But unfortunately

these "ifs" stand mountain-high here, all the essential factors being

indeterminate. Nevertheless, the geologists contended that they could

easily make out a case proving that the constructive and destructive

work still in evidence, to say nothing of anterior revolutions, could

not have been accomplished in less than from twenty-five to fifty

millions of years.

This computation would have carried little weight with the physicists

had it not chanced that another computation of their own was soon made

which had even more startling results. This computation, made by Lord

Kelvin, was based on the rate of loss of heat by the earth. It thus

resembled the previous solar estimate in method. But the result was very

different, for the new estimate seemed to prove that a period of from

one hundred to two hundred millions of years has elapsed since the final

crust of the earth formed.

With this all controversy ceased, for the most grasping geologist or

biologist would content himself with a fraction of that time. But the

case for the geologist was to receive yet another prop from the studies

of radio-activity, which seem to prove that the atom of matter has in

store a tremendous, supply of potential energy which may be drawn on

in a way to vitiate utterly all the computations to which I have just

referred. Thus a particle of radium is giving out heat incessantly

in sufficient quantity to raise its own weight of water to the

boiling-point in an hour. The demonstrated wide distribution of

radio-active matter--making it at least an open question whether all

matter does not possess this property in some degree--has led to the

suggestion that the total heat of the sun may be due to radio-active

matter in its substance. Obviously, then, all estimates of the sun's age

based on the heat-supply must for the present be held quite in abeyance.

What is more to the point, however, is the fact, which these varying

estimates have made patent, that computations of the age of the earth

based on any data at hand are little better than rough guesses. Long

before the definite estimates were undertaken, geologists had proved

that the earth is very, very old, and it can hardly be said that

the attempted computations have added much of definiteness to that

proposition. They have, indeed, proved that the period of time to be

drawn upon is not infinite; but the nebular hypothesis, to say nothing

of common-sense, carried us as far as that long ago.

If the computations in question have failed of their direct purpose,

however, they have been by no means lacking in important collateral

results. To mention but one of these, Lord Kelvin was led by this

controversy over the earth's age to make his famous computation in which

he proved that the telluric structure, as a whole, must have at least

the rigidity of steel in order to resist the moon's tidal pull as it

does. Hopkins had, indeed, made a somewhat similar estimate as early as

1839, proving that the earth's crust must be at least eight hundred or

a thousand miles in thickness; but geologists had utterly ignored

this computation, and the idea of a thin crust on a fluid interior had

continued to be the orthodox geological doctrine. Since Lord Kelvin's

estimate was made, his claim that the final crust of the earth could

not have formed until the mass was solid throughout, or at least until

a honeycomb of solid matter had been bridged up from centre to

circumference, has gained pretty general acceptance. It still remains

an open question, however, as to what proportion the lacunas of molten

matter bear at the present day to the solidified portions, and therefore

to what extent the earth will be subject to further shrinkage and

attendant surface contortions. That some such lacunae do exist is

demonstrated daily by the phenomena of volcanoes. So, after all, the

crust theory has been supplanted by a compromise theory rather than

completely overthrown, and our knowledge of the condition of the

telluric depths is still far from definite. If so much uncertainty

attends these fundamental questions as to the earth's past and present,

it is not strange that open problems as to her future are still

more numerous. We have seen how, according to Professor Darwin's

computations, the moon threatens to come back to earth with destructive

force some day. Yet Professor Darwin himself urges that there are

elements of fallibility in the data involved that rob the computation of

all certainty. Much the same thing is true of perhaps all the estimates

that have been made as to the earth's ultimate fate. Thus it has been

suggested that, even should the sun's heat not forsake us, our day will

become month-long, and then year-long; that all the water of the globe

must ultimately filter into its depths, and all the air fly off into

space, leaving our earth as dry and as devoid of atmosphere as the moon;

and, finally, that ether-friction, if it exist, or, in default of that,

meteoric friction, must ultimately bring the earth back to the sun. But

in all these prognostications there are possible compensating factors

that vitiate the estimates and leave the exact results in doubt. The

last word of the cosmic science of our generation is a prophecy of

evil--if annihilation be an evil. But it is left for the science of

another generation to point out more clearly the exact terms in which

the prophecy is most likely to be fulfilled.

PHYSICAL PROBLEMS

In regard to all these cosmic and telluric problems, it will be seen,

there is always the same appeal to one central rule of action--the law

of gravitation. When we turn from macrocosm to microcosm it would

appear as if new forces of interaction were introduced in the powers of

cohesion and of chemical action of molecules and atoms. But Lord Kelvin

has argued that it is possible to form such a conception of the forms

and space relations of the ultimate particles of matter that their

mutual attractions may be explained by invoking that same law of

gravitation which holds the stars and planets in their course. What,

then, is this all-compassing power of gravitation which occupies so

central a position in the scheme of mechanical things?

The simple answer is that no man knows. The wisest physicist of

to-day will assure you that he knows absolutely nothing of the why of

gravitation--that he can no more explain why a stone tossed into the

air falls back to earth than can the boy who tosses the stone. But while

this statement puts in a nutshell the scientific status of explanations

of gravitation, yet it is not in human nature that speculative

scientists should refrain from the effort to explain it. Such efforts

have been made; yet, on the whole, they are surprisingly few in number;

indeed, there are but two that need claim our attention here, and one

of these has hardly more than historical interest. One of these is the

so-called ultramundane-corpuscle hypothesis of Le Sage; the other is

based on the vortex theory of matter.

The theory of Le Sage assumes that the entire universe is filled with

infinitely minute particles flying in right lines in every direction

with inconceivable rapidity. Every mass of tangible matter in the

universe is incessantly bombarded by these particles, but any two

non-contiguous masses (whether separated by an infinitesimal space or by

the limits of the universe) are mutually shielded by one another from a

certain number of the particles, and thus impelled towards one another

by the excess of bombardment on their opposite sides. What applies to

two masses applies also, of course, to any number of masses--in short,

to all the matter in the universe. To make the hypothesis workable, so

to say, it is necessary to assume that the "ultramundane" particles are

possessed of absolute elasticity, so that they rebound from one another

on collision without loss of speed. It is also necessary to assume that

all tangible matter has to an almost unthinkable degree a sievelike

texture, so that the vast proportion of the coercive particles pass

entirely through the body of any mass they encounter--a star or world,

for example--without really touching any part of its actual substance.

This assumption is necessary because gravitation takes no account of

mere corporeal bulk, but only of mass or ultimate solidarity. Thus a

very bulky object may be so closely meshed that it retards

relatively few of the corpuscles, and hence gravitates with relative

feebleness--or, to adopt a more familiar mode of expression, is light in

weight.

This is certainly heaping hypotheses together in a reckless way, and

it is perhaps not surprising that Le Sage's conception did not at first

arouse any very great amount of interest. It was put forward about

a century ago, but for two or three generations remained practically

unnoticed. The philosophers of the first half of our century seem

to have despaired of explaining gravitation, though Faraday long

experimented in the hope of establishing a relation between gravitation

and electricity or magnetism. But not long after the middle of

the century, when a new science of dynamics was claiming paramount

importance, and physicists were striving to express all tangible

phenomena intenus of matter in motion, the theory of Le Sage was

revived and given a large measure of attention. It seemed to have at

least the merit of explaining the facts without conflicting with any

known mechanical law, which was more than could be said of any other

guess at the question that had ever been made.