short though ever-lengthening fragment of life which lies behind them;
they are wholly bent on that which is to come. The eyes of the aged turn
wistfully again and again to the past; as the old glide down the
inevitable slope, their present becomes a living over again the life which
has gone before, and the future takes on the shape of a brief lengthening
of the past. May I this evening venture to give rein to the impulses of
advancing years? May I, at this last meeting of the association in the
eighteen hundreds, dare to dwell for a while upon the past, and to call to
mind a few of the changes which have taken place in the world since those
autumn days in which men were saying to each other that the last of the
seventeen hundreds was drawing toward its end?
Dover, in the year of our Lord 1799, was in many ways unlike the Dover of
to-day. On moonless nights men groped their way in its narrow streets by
the help of swinging lanterns and smoky torches, for no lamps lit the
ways. By day the light of the sun struggled into the houses through narrow
panes of blurred glass. Though the town then, as now, was one of the chief
portals to and from the countries beyond the seas, the means of travel was
scanty and dear, available for the most part to the rich alone, and for
all beset with discomfort and risk. Slow and uncertain was the carriage
of goods, and the news of the world outside came to the town (though it,
from its position, learned more than most towns) tardily, fitfully, and
often falsely. The people of Dover sat then much in dimness, if not in
darkness, and lived in large measure on themselves. They who study the
phenomena of living beings tell us that light is the great stimulus of
life, and that the fullness of the life of a being or of any of its
members may be measured by the variety, the swiftness, and the certainty
of the means by which it is in touch with its surroundings. Judged from
this standpoint, life at Dover then, as indeed elsewhere, must have fallen
far short of the life of to-day.
The same study of living beings, however, teaches us that while from one
point of view the environment seems to mould the organism, from another
point the organism seems to be master of its environment. Going behind the
change of circumstances, we may raise the question, the old question, Was
life in its essence worth more then than now? Has there been a real
advance?
Let me at once relieve your minds by saying that I propose to leave this
question in the main unanswered. It may be, or it may not be, that man's
grasp of the beautiful and of the good, if not looser, is not firmer than
it was a hundred years ago. It may be, or it may not be, that man is no
nearer to absolute truth, to seeing things as they really are, than he was
then. I will merely ask you to consider with me for a few minutes how far
and in what ways man's laying hold of that aspect of, or part of, truth
which we call natural knowledge, or sometimes science, differed in 1799
from what it is to-day, and whether that change must not be accounted a
real advance, a real improvement in man.
I do not propose to weary you by what in my hands would be the rash effort
of attempting a survey of all the scientific results of the nineteenth
century. It will be enough if for a little while I dwell on some few of
the salient features distinguishing the way in which we nowadays look
upon, and during the coming week shall speak of, the works of nature
around us--though those works themselves, save for the slight shifting
involved in a secular change, remain exactly the same--from the way in
which they were looked upon and might have been spoken of at a gathering
of philosophers at Dover in 1799, and I ask your leave to do so.
In the philosophy of the ancients earth, fire, air, and water were called
"the elements." It was thought, and rightly thought, that a knowledge of
them and of their attributes was a necessary basis of a knowledge of the
ways of nature. Translated into modern language, a knowledge of these
"elements" of old means a knowledge of the composition of the atmosphere,
of water, and of all the other things which we call matter, as well as a
knowledge of the general properties of gases, liquids, and solids, and of
the nature and effects of combustion. Of all these things our knowledge
to-day is large and exact, and, though ever enlarging, in some respects
complete. When did that knowledge begin to become exact?
To-day the children in our schools know that the air which wraps round the
globe is not a single thing, but is made up of two things, oxygen and
nitrogen,[3] mingled together. They know, again, that water is not a
single thing, but the product of two things, oxygen and hydrogen, joined
together. They know that when the air makes the fire burn and gives the
animal life, it is the oxygen in it which does the work. They know that
all round them things are undergoing that union with oxygen which we call
oxidation, and that oxidation is the ordinary source of heat and light.
Let me ask you to picture to yourselves what confusion there would be
to-morrow, not only in the discussions at the sectional meetings of our
association, but in the world at large, if it should happen that in the
coming night some destroying touch should wither up certain tender
structures in all our brains and wipe out from our memories all traces of
the ideas which cluster in our minds around the verbal tokens, oxygen and
oxidation. How could any of us--not the so-called man of science alone,
but even the man of business and the man of pleasure--go about his ways
lacking those ideas? Yet those ideas were, in 1799, lacking to all but a
few.
Although in the third quarter of the seventeenth century the light of
truth about oxidation and combustion had flashed out in the writings of
John Mayow, it came as a flash only, and died away as soon as it had come.
For the rest of that century, and for the greater part of the next,
philosophers stumbled about in darkness, misled for most of the time by
the phantom conception which they called phlogiston. It was not until the
end of the third quarter of the eighteenth century that the new light,
which has burned steadily ever since, lit up the minds of the men of
science. The light came at nearly the same time from England and from
France. Rounding off the sharp corners of controversy, and joining, as we
may fitly do to-day, the two countries as twin bearers of a common crown,
we may say that we owe the truth to Priestley, to Lavoisier, and to
Cavendish. If it was Priestley who was the first to demonstrate the
existence of what we now call oxygen, it is to Lavoisier that we owe the
true conception of the nature of oxidation and the clear exposition of the
full meaning of Priestley's discovery; while the knowledge of the
composition of water, the necessity complement of the knowledge of oxygen,
came to us through Cavendish and, we may perhaps add, through Watt.
The date of Priestley's discovery of oxygen is 1774; Lavoisier's classic
memoir "On the nature of the principle which enters into combination with
metals during calcination" appeared in 1775, and Cavendish's paper on the
composition of water did not see the light until 1784.
During the last quarter of the eighteenth century this new idea of oxygen
and oxidation was struggling into existence. How new was the idea, is
illustrated by the fact that Lavoisier himself at first spoke of that
which he was afterwards, namely, in 1778, led to call oxygen, the name by
which it has since been known, as "the principle which enters into
combination." What difficulties its acceptance met with is illustrated by
the fact that Priestley himself refused to the end of his life to grasp
the true bearings of the discovery which he had made.
In the year 1799 the knowledge of oxygen, of the nature of water and of
air, and indeed the true conception of chemical composition and chemical
change, was hardly more than beginning to be; and the century had to pass
wholly away before the next great chemical idea, which we know by the name
of the atomic theory of John Dalton, was made known. We have only to read
the scientific literature of the time to recognize that a truth which is
now not only woven as a master-thread into all our scientific conceptions,
but even enters largely into the everyday talk and thoughts of educated
people, was, a hundred years ago, struggling into existence among the
philosophers themselves. It was all but absolutely unknown to the large
world outside those select few.
If there be one word of science which is writ large on the life of the
present time, it is the word "electricity." It is, I take it, writ larger
than any other word. The knowledge which it denotes has carried its
practical results far and wide into our daily life, while the theoretical
conceptions which it signifies pierce deep into the nature of things. We
are to-day proud, and justly proud, both of the material triumphs and of
the intellectual gains which it has brought us, and we are full of even
larger hopes of it in the future.
At what time did this bright child of the nineteenth century have its
birth?
He who listened to the small group of philosophers of Dover, who in 1799
might have discoursed of natural knowledge, would perhaps have heard much
of electric machines, of electric sparks, of the electric fluid, and even
of positive and negative electricity; for frictional electricity had long
been known and even carefully studied. Probably one or more of the group,
dwelling on the observations which Galvani, an Italian, had made known
some twenty years before, developed views on the connection of electricity
with the phenomena of living bodies. Possibly one of them was exciting the
rest by telling how he had just heard that a professor at Pavia, one
Volta, had discovered that electricity could be produced, not only by
rubbing together particular bodies, but by the simple contact of two
metals, and had thereby explained Galvani's remarkable results. For,
indeed, as we shall hear from Professor Fleming, it was in that very year,
1799, that electricity as we now know it took its birth. It was then that
Volta brought to light the apparently simple truths out of which so much
has sprung. The world, it is true, had to wait for yet some twenty years
before both the practical and theoretic worth of Volta's discovery became
truly pregnant under the fertilizing influence of another discovery. The
loadstone and its magnetic virtues had, like the electrifying power of
rubbed amber, long been an old story. But, save for the compass, not much
had come from it. And even Volta's discovery might have long remained
relatively barren had it been left to itself. When, however, in 1819,
Oersted made known his remarkable observations on the relations of
electricity to magnetism, he made the contact needed for the flow of a new
current of ideas. And it is perhaps not too much to say that those ideas,
developing during the years of the rest of the century with an
ever-accelerating swiftness, have wholly changed man's material relations
to the circumstances of life, and at the same time carried him far in his
knowledge of the nature of things.
Of all the various branches of science, none perhaps is to-day, none for
these many years past has been, so well known to, even if not understood
by, most people as that of geology. Its practical lessons have brought
wealth to many; its fairy tales have brought delight to more; and round it
hovers the charm of danger, for the conclusions to which it leads touch on
the nature of man's beginning.
In 1799 the science of geology, as we now know it, was struggling into
birth. There had been from of old cosmogonies, theories as to how the
world had taken shape out of primeval chaos. In that fresh spirit which
marked the zealous search after natural knowledge pursued in the middle
and latter part of the seventeenth century, the brilliant Stenson, in
Italy, and Hooke, in England, had laid hold of some of the problems
presented by fossil remains, and Woodward, with others, had labored in the
same field. In the eighteenth century, especially in its latter half,
men's minds were busy about the physical agencies determining or modifying
the features of the earth's crust; water and fire, subsidence from a
primeval ocean and transformation by outbursts of the central heat,
Neptune and Pluto were being appealed to, by Werner on the one hand and by
Demarest on the other, in explanation of the earth's phenomena. The way
was being prepared, theories and views were abundant, and many sound
observations had been made; and yet the science of geology, properly so
called, the exact and proved knowledge of the successive phases of the
world's life, may be said to date from the closing years of the eighteenth
century.
In 1783 James Hutton put forward in a brief memoir his Theory of the
Earth, which, in 1795, two years before his death, he expanded into a
book; but his ideas failed to lay hold of men's minds until the century
had passed away, when, in 1802, they found an able expositor in John
Playfair. The very same year that Hutton published his book, Cuvier came
to Paris and almost forthwith began, with Brongniart, his immortal
researches into the fossils of Paris and its neighborhood. And four years
later, in the year 1799 itself, William Smith's tabular list of strata and
fossils saw the light. It is, I believe, not too much to say that out of
these, geology, as we now know it, sprang.
It was thus in the closing years of the eighteenth century that was begun
the work which the nineteenth century has carried forward to such great
results; but at this time only the select few had grasped the truth, and
even they only the beginning of it. Outside a narrow circle the thoughts
even of the educated about the history of the globe were bounded by the
story of the Deluge,--though the story was often told in a strange
fashion,--or were guided by fantastic views of the plastic forces of a
sportive nature.
In another branch of science, in that which deals with the problems
presented by living beings, the thoughts of men in 1799 were also very
different from the thoughts of men to-day. It is a very old quest, the
quest after the knowledge of the nature of living beings, one of the
earliest on which man set out; for it promised to lead him to a knowledge
of himself--a promise which perhaps is still before us, but the
fulfillment of which is yet far off. As time has gone on, the pursuit of
natural knowledge has seemed to lead man away from himself into the
furthermost parts of the universe, and into secret workings of Nature in
which he appears to be of little or no account; and his knowledge of the
nature of living things, and so of his own nature, has advanced slowly,
waiting till the progress of other branches of natural knowledge can bring
it aid. Yet in the past hundred years the biologic sciences, as we now
call them, have marched rapidly onward.
We may look upon a living body as a machine doing work in accordance with
certain laws, and may seek to trace out the working of the inner wheels:
how these raise up the lifeless dust into living matter, and let the
living matter fall away again into dust, giving out movement and heat. Or
we may look upon the individual life as a link in a long chain, joining
something which went before to something about to come, a chain whose
beginning lies hid in the farthest past, and may seek to know the ties
which bind one life to another. As we call up to view the long series of
living forms, living now or flitting like shadows on the screen of the
past, we may strive to lay hold of the influences which fashion the
garment of life. Whether the problems of life are looked upon from the one
point of view or the other, we to-day, not biologists only, but all of us,
have gained a knowledge hidden even from the philosophers a hundred years
ago.
Of the problems presented by the living body viewed as a machine, some may
be spoken of as mechanical, others as physical, and yet others as
chemical, while some are, apparently at least, none of these. In the
seventeenth century William Harvey, laying hold of the central mechanism
of the blood stream, opened up a path of inquiry which his own age and the
century which followed trod with marked success. The knowledge of the
mechanism of the animal and of the plant advanced apace, but the physical
and chemical problems had yet to wait. The eighteenth century, it is true,
had its physics and its chemistry; but, in relation at least to the
problems of the living being, a chemistry which knew not oxygen and a
physics which knew not the electricity of chemical action were of little
avail. The philosopher of 1799, when he discussed the functions of the
animal or of the plant involving chemical changes, was fain, for the most
part, as were his predecessors in the century before, to have recourse to
such vague terms as "fermentation" and the like; to-day our treatises on
physiology are largely made up of precise and exact expositions of the
play of physical agencies and chemical bodies in the living organisms. He
made use of the words "vital force" or "vital principle," not as an
occasional, but as a common, explanation of the phenomena of the living
body. During the present century, especially during its latter half, the
idea embodied in those words has been driven away from one seat after
another; if we use it now when we are dealing with the chemical and
physical events of life, we use it with reluctance, as a _deus ex machina_
to be appealed to only when everything else has failed.
Some of the problems--and those, perhaps, the chief problems--of the
living body have to be solved, neither by physical nor by chemical
methods, but by methods of their own. Such are the problems of the nervous
system. In respect to these the men of 1799 were on the threshold of a
pregnant discovery. During the latter part of this nineteenth century,
especially during its last quarter, the analysis of the mysterious
processes in the nervous system, and especially in the brain, which issue
as feeling, thought, and the power to move, has been pushed forward with a
success conspicuous in its practical, and full of promise in its
theoretical, gains. That analysis may be briefly described as a following
up of threads. We now know that what takes place along a tiny thread which
we call a nerve fibre differs from that which takes place along its fellow
threads, that differing nervous impulses travel along different nervous
fibres, and that nervous and physical events are the outcome of the
clashing of nervous impulses as they sweep along the closely woven web of
living threads of which the brain is made. We have learned by experiment
and by observation that the pattern of the web determines the play of the
impulses, and we can already explain many of the obscure problems, not
only of nervous disease, but of nervous life, by an analysis which is a
tracking out of the devious and linked path of nervous threads. The very
beginning of this analysis was unknown in 1799. Men knew that nerves were
the agents of feeling and of the movements of muscles; they had learned
much about what this part or that part of the brain could do; but they did
not know that one nerve fibre differed from another in the very essence of
its work. It was just about the end of the eighteenth century, or the
beginning of the nineteenth, that an English surgeon began to ponder over
a conception which, however, he did not make known until some years later,
and which did not gain complete demonstration and full acceptance until
still more years had passed away. It was in 1811, in a tiny pamphlet
published privately, that Charles Bell put forth his New Idea, that the
nervous system is constructed on the principle that "the nerves are not
single nerves possessing various powers, but bundles of different nerves,
whose filaments are united for the convenience of distribution, but which
are distinct in office, as they are in origin, from the brain."
Our present knowledge of the nervous system is to a large extent only an
exemplification and expansion of Charles Bell's New Idea, and has its
origin in that.
If we pass from the problems of the living organism viewed as a machine to
those presented by the varied features of the different creatures who have
lived or who still live on the earth, we at once call to mind that the
middle years of the nineteenth century mark an epoch in biologic thought
such as never came before; for it was then that Charles Darwin gave to the
world the "Origin of Species."
That work, however, with all the far-reaching effects which it has had,
could have had little or no effect, or, rather, could not have come into
existence, had not the earlier half of the century been in travail
preparing for its coming. For the germinal idea of Darwin appeals, as to
witnesses, to the results of two lines of biologic investigation which
were almost unknown to the men of the eighteenth century.
To one of these lines I have already referred. Darwin, as we know,
appealed to the geological record; and we also know how that record,
imperfect as it was then, and imperfect as it must always remain, has
since his time yielded the most striking proofs of at least one part of
his general conception. In 1799 there was, as we have seen, no geological
record at all.
Of the other line I must say a few words.
To-day the merest beginner in biologic study, or even that exemplar of
acquaintance without knowledge, the general reader, is aware that every
living being, even man himself, begins its independent existence as a tiny
ball, of which we can, even acknowledging to the full the limits of the
optical analysis at our command, assert with confidence that in structure,
using that word in its ordinary sense, it is in all cases absolutely
simple. It is equally well known that the features of form which supply
the characters of a grown-up living being, all the many and varied
features of even the most complex organism, are reached as the goal of a
road, at times a long road, of successive changes; that the life of every
being, from the ovum to its full estate, is a series of shifting scenes,
which come and go, sometimes changing abruptly, sometimes melting the one
into the other, like dissolving views--all so ordained that often the
final shape with which the creature seems to begin, or is said to begin,
its life in the world is the outcome of many shapes, clothed with which it
in turn has lived many lives before its seeming birth.
All, or nearly all, the exact knowledge of the labored way in which each
living creature puts on its proper shape and structure is the heritage of
the present century. Although the way in which the chick is moulded in the
egg was not wholly unknown even to the ancients, and in later years had
been told, first in the sixteenth century by Fabricius, then in the
seventeenth century, in a more clear and striking manner, by the great
Italian naturalist, Malpighi, the teaching thus offered had been neglected
or misinterpreted. At the close of the eighteenth century the dominant
view was that in the making of a creature out of the egg there was no
putting on of wholly new parts, no epigenesis. It was taught that the
entire creature lay hidden in the egg, hidden by reason of the very
transparency of its substance; lay ready-made, but folded up, as it were;
and that the process of development within the egg or within the womb was
a mere unfolding, a simple evolution. Nor did men shrink from accepting
the logical outcome of such a view--namely, that within the unborn
creature itself lay in like manner, hidden and folded up, its offspring
also, and within that, again, its offspring in turn, after the fashion of
a cluster of ivory balls carved by Chinese hands, one within the other.