an organic crystal, if I may use the phrase, and that we could suddenly
see it exerting all these powers, what wonderful new ideas and new
questions would arise in our minds! The great new question would be,
"How does all this take place?" the chief new idea would be, the idea of
adaptation to purpose,--the notion, that the constituents of animal
bodies are not mere unconnected parts, but organs working together to an
end. Let us consider the tail of the lobster again from this point of
view. Morphology has taught us that it is a series of segments composed
of homologous parts, which undergo various modifications--beneath and
through which a common plan of formation is discernible. But if I look
at the same part physiologically, I see that it is a most beautifully
constructed organ of locomotion, by means of which the animal can
swiftly propel itself either backwards or forwards.
But how is this remarkable propulsive machine made to perform its
functions? If I were suddenly to kill one of these animals and to take
out all the soft parts, I should find the shell to be perfectly inert,
to have no more power of moving itself than is possessed by the
machinery of a mill, when disconnected from its steam-engine or
water-wheel. But if I were to open it, and take out the viscera only,
leaving the white flesh, I should perceive that the lobster could bend
and extend its tail as well as before. If I were to cut off the tail, I
should cease to find any spontaneous motion in it; but on pinching any
portion of the flesh, I should observe that it underwent a very curious
change--each fibre becoming shorter and thicker. By this act of
contraction, as it is termed, the parts to which the ends of the fibre
are attached are, of course, approximated; and according to the
relations of their points of attachment to the centres of motion of the
different rings, the bending or the extension of the tail results. Close
observation of the newly opened lobster would soon show that all its
movements are due to the same cause--the shortening and thickening of
these fleshy fibres, which are technically called muscles.
Here, then, is a capital fact. The movements of the lobster are due to
muscular contractility. But why does a muscle contract at one time and
not at another? Why does one whole group of muscles contract when the
lobster wishes to extend his tail, and another group, when he desires to
bend it? What is it originates, directs, and controls the motive power?
Experiment, the great instrument for the ascertainment of truth in
physical science, answers this question for us. In the head of the
lobster there lies a small mass of that peculiar tissue which is known
as nervous substance. Cords of similar matter connect this brain of the
lobster, directly or indirectly, with the muscles. Now, if these
communicating cords are cut, the brain remaining entire, the power of
exerting what we call voluntary motion in the parts below the section is
destroyed; and on the other hand, if, the cords remaining entire, the
brain mass be destroyed, the same voluntary mobility is equally lost.
Whence the inevitable conclusion is, that the power of originating these
motions resides in the brain, and is propagated along the nervous cords.
In the higher animals the phænomena which attend this transmission have
been investigated, and the exertion of the peculiar energy which resides
in the nerves has been found to be accompanied by a disturbance of the
electrical state of their molecules.
If we could exactly estimate the signification of this disturbance; if
we could obtain the value of a given exertion of nerve force by
determining the quantity of electricity, or of heat, of which it is the
equivalent; if we could ascertain upon what arrangement, or other
condition of the molecules of matter, the manifestation of the nervous
and muscular energies depends, (and doubtless science will some day or
other ascertain these points,) physiologists would have attained their
ultimate goal in this direction; they would have determined the relation
of the motive force of animals to the other forms of force found in
nature; and if the same process had been successfully performed for all
the operations which are carried on in, and by, the animal frame,
physiology would be perfect, and the facts of morphology and
distribution would be deducible from the laws which physiologists had
established, combined with those determining the condition of the
surrounding universe.
There is not a fragment of the organism of this humble animal, whose
study would not lead us into regions of thought as large as those which
I have briefly opened up to you; but what I have been saying, I trust,
has not only enabled you to form a conception of the scope and purport
of zoology, but has given you an imperfect example of the manner in
which, in my opinion, that science, or indeed any physical science, may
be best taught. The great matter is, to make teaching real and
practical, by fixing the attention of the student on particular facts;
but at the same time it should be rendered broad and comprehensive, by
constant reference to the generalizations of which all particular facts
are illustrations. The lobster has served as a type of the whole animal
kingdom, and its anatomy and physiology have illustrated for us some of
the greatest truths of biology. The student who has once seen for
himself the facts which I have described, has had their relations
explained to him, and has clearly comprehended them, has, so far, a
knowledge of zoology, which is real and genuine, however limited it may
be, and which is worth more than all the mere reading knowledge of the
science he could ever acquire. His zoological information is, so far,
knowledge and not mere hearsay.
And if it were my business to fit you for the certificate in zoological
science granted by this department, I should pursue a course precisely
similar in principle to that which I have taken to-night. I should
select a fresh-water sponge, a fresh-water polype or a _Cyanæa_, a
fresh-water mussel, a lobster, a fowl, as types of the five primary
divisions of the animal kingdom. I should explain their structure very
fully, and show how each illustrated the great principles of zoology.
Having gone very carefully and fully over this ground, I should feel
that you had a safe foundation, and I should then take you in the same
way, but less minutely, over similarly selected illustrative types of
the classes; and then I should direct your attention to the special
forms enumerated under the head of types, in this syllabus, and to the
other facts there mentioned.
That would, speaking generally, be my plan. But I have undertaken to
explain to you the best mode of acquiring and communicating a knowledge
of zoology, and you may therefore fairly ask me for a more detailed and
precise account of the manner in which I should propose to furnish you
with the information I refer to.
My own impression is, that the best model for all kinds of training in
physical science is that afforded by the method of teaching anatomy, in
use in the medical schools. This method consists of three
elements--lectures, demonstrations, and examinations.
The object of lectures is, in the first place, to awaken the attention
and excite the enthusiasm of the student; and this, I am sure, may be
effected to a far greater extent by the oral discourse and by the
personal influence of a respected teacher than in any other way.
Secondly, lectures have the double use of guiding the student to the
salient points of a subject, and at the same time forcing him to attend
to the whole of it, and not merely to that part which takes his fancy.
And lastly, lectures afford the student the opportunity of seeking
explanations of those difficulties which will; and indeed ought to,
arise in the course of his studies.
But for a student to derive the utmost possible value from lectures,
several precautions are needful.
I have a strong impression that the better a discourse is, as an
oration, the worse it is as a lecture. The flow of the discourse carries
you on without proper attention to its sense; you drop a word or a
phrase, you lose the exact meaning for a moment, and while you strive to
recover yourself, the speaker has passed on to something else.
The practice I have adopted of late years, in lecturing to students, is
to condense the substance of the hour's discourse into a few dry
propositions, which are read slowly and taken down from dictation; the
reading of each being followed by a free commentary, expanding and
illustrating the proposition, explaining terms, and removing any
difficulties that may be attackable in that way, by diagrams made
roughly, and seen to grow under the lecturer's hand. In this manner you,
at any rate, insure the co-operation of the student to a certain extent.
He cannot leave the lecture-room entirely empty if the taking of notes
is enforced; and a student must be preternaturally dull and mechanical,
if he can take notes and hear them properly explained, and yet learn
nothing.
What books shall I read? is a question constantly put by the student to
the teacher. My reply usually is, "None: write your notes out carefully
and fully; strive to understand them thoroughly; come to me for the
explanation of anything you cannot understand; and I would rather you
did not distract your mind by reading." A properly composed course of
lectures ought to contain fully as much matter as a student can
assimilate in the time occupied by its delivery; and the teacher should
always recollect that his business is to feed, and not to cram the
intellect. Indeed, I believe that a student who gains from a course of
lectures the simple habit of concentrating his attention upon a
definitely limited series of facts, until they are thoroughly mastered,
has made a step of immeasurable importance.
But, however good lectures may be, and however extensive the course of
reading by which they are followed up, they are but accessories to the
great instrument of scientific teaching--demonstration. If I insist
unweariedly, nay fanatically, upon the importance of physical science as
an educational agent, it is because the study of any branch of science,
if properly conducted, appears to me to fill up a void left by all other
means of education. I have the greatest respect and love for literature;
nothing would grieve me more than to see literary training other than a
very prominent branch of education: indeed, I wish that real literary
discipline were far more attended to than it is; but I cannot shut my
eyes to the fact, that there is a vast difference between men who have
had a purely literary, and those who have had a sound scientific,
training.
Seeking for the cause of this difference, I imagine I can find it in the
fact, that, in the world of letters, learning and knowledge are one, and
books are the source of both; whereas in science, as in life, learning
and knowledge are distinct, and the study of things, and not of books,
is the source of the latter.
All that literature has to bestow may be obtained by reading and by
practical exercise in writing, and in speaking; but I do not exaggerate
when I say, that none of the best gifts of science are to be won by
these means. On the contrary, the great benefit which a scientific
education bestows, whether as training or as knowledge, is dependent
upon the extent to which the mind of the student is brought into
immediate contact with facts--upon the degree to which he learns the
habit of appealing directly to Nature, and of acquiring through his
senses concrete images of those properties of things, which are, and
always will be, but approximatively expressed in human language. Our way
of looking at Nature, and of speaking about her, varies from year to
year; but a fact once seen, a relation of cause and effect, once
demonstratively apprehended, are possessions which neither change nor
pass away, but, on the contrary, form fixed centres, about which other
truths aggregate by natural affinity.
Therefore, the great business of the scientific teacher is, to imprint
the fundamental, irrefragable facts of his science, not only by words
upon the mind, but by sensible impressions upon the eye, and ear, and
touch of the student, in so complete a manner, that every term used, or
law enunciated, should afterwards call up vivid images of the particular
structural, or other, facts which furnished the demonstration of the
law, or the illustration of the term.
Now this important operation can only be achieved by constant
demonstration, which may take place to a certain imperfect extent during
a lecture, but which ought also to be carried on independently, and
which should be addressed to each individual student, the teacher
endeavouring, not so much to show a thing to the learner, as to make him
see it for himself.
I am well aware that there are great practical difficulties in the way
of effectual zoological demonstrations. The dissection of animals is
not altogether pleasant, and requires much time; nor is it easy to
secure an adequate supply of the needful specimens. The botanist has
here a great advantage; his specimens are easily obtained, are clean and
wholesome, and can be dissected in a private house as well as anywhere
else; and hence, I believe, the fact, that botany is so much more
readily and better taught than its sister science. But, be it difficult
or be it easy, if zoological science is to be properly studied,
demonstration, and, consequently, dissection, must be had. Without it,
no man can have a really sound knowledge of animal organization.
A good deal may be done, however, without actual dissection on the
student's part, by demonstration upon specimens and preparations; and in
all probability it would not be very difficult, were the demand
sufficient, to organize collections of such objects, sufficient for all
the purposes of elementary teaching, at a comparatively cheap rate. Even
without these, much might be effected, if the zoological collections,
which are open to the public, were arranged according to what has been
termed the "typical principle;" that is to say, if the specimens exposed
to public view were so selected, that the public could learn something
from them, instead of being, as at present, merely confused by their
multiplicity. For example, the grand ornithological gallery at the
British Museum contains between two and three thousand species of birds,
and sometimes five or six specimens of a species. They are very pretty
to look at, and some of the cases are, indeed, splendid; but undertake
to say, that no man but a professed ornithologist has ever gathered
much information from the collection. Certainly, no one of the tens of
thousands of the general public who have walked through that gallery
ever knew more about the essential peculiarities of birds when he left
the gallery, than when he entered it. But if, somewhere in that vast
hall, there were a few preparations, exemplifying the leading structural
peculiarities and the mode of development of a common fowl; if the types
of the genera, the leading modifications in the skeleton, in the plumage
at various ages, in the mode of nidification, and the like, among birds,
were displayed; and if the other specimens were put away in a place
where the men of science, to whom they are alone useful, could have free
access to them, I can conceive that this collection might become a great
instrument of scientific education.
The last implement of the teacher to which I have adverted is
examination--a means of education now so thoroughly understood that I
need hardly enlarge upon it. I hold that both written and oral
examinations are indispensable, and, by requiring the description of
specimens, they may be made to supplement demonstration.
Such is the fullest reply the time at my disposal will allow me to give
to the question--how may a knowledge of zoology be best acquired and
communicated?
But there is a previous question which may be moved, and which, in fact,
I know many are inclined to move. It is the question, why should
training masters be encouraged to acquire a knowledge of this, or any
other branch of physical science? What is the use, it is said, of
attempting to make physical science a branch of primary education? It
is not probable that teachers, in pursuing such studies, will be led
astray from the acquirement of more important but less attractive
knowledge? And, even if they can learn something of science without
prejudice to their usefulness, what is the good of their attempting to
instil that knowledge into boys whose real business is the acquisition
of reading, writing, and arithmetic?
These questions are, and will be, very commonly asked, for they arise
from that profound ignorance of the value and true position of physical
science, which infests the minds of the most highly educated and
intelligent classes of the community. But if I did not feel well assured
that they are capable of being easily and satisfactorily answered; that
they have been answered over and over again; and that the time will come
when men of liberal education will blush to raise such questions,--I
should be ashamed of my position here to-night. Without doubt, it is
your great and very important function to carry out elementary
education; without question, anything that should interfere with the
faithful fulfilment of that duty on your part would be a great evil; and
if I thought that your acquirement of the elements of physical science,
and your communication of those elements to your pupils, involved any
sort of interference with your proper duties, I should be the first
person to protest against your being encouraged to do anything of the
kind.
But is it true that the acquisition of such a knowledge of science as is
proposed, and the communication of that knowledge, are calculated to
weaken your usefulness? Or may I not rather ask, is it possible for you
to discharge your functions properly without these aids?
What is the purpose of primary intellectual education? I apprehend that
its first object is to train the young in the use of those tools
wherewith men extract knowledge from the ever-shifting succession of
phenomena which pass before their eyes; and that its second object is to
inform them of the fundamental laws which have been found by experience
to govern the course of things, so that they may not be turned out into
the world naked, defenceless, and a prey to the events they might
control.
A boy is taught to read his own and other languages, in order that he
may have access to infinitely wider stores of knowledge than could ever
be opened to him by oral intercourse with his fellow men; he learns to
write, that his means of communication with the rest of mankind may be
indefinitely enlarged, and that he may record and store up the knowledge
he acquires. He is taught elementary mathematics, that he may understand
all those relations of number and form, upon which the transactions of
men, associated in complicated societies, are built, and that he may
have some practice in deductive reasoning.
All these operations of reading, writing, and ciphering, are
intellectual tools, whose use should, before all things, be learned, and
learned thoroughly; so that the youth may be enabled to make his life
that which it ought to be, a continual progress in learning and in
wisdom.
But, in addition, primary education endeavours to fit a boy out with a
certain equipment of positive knowledge. He is taught the great laws of
morality; the religion of his sect; so much history and geography as
will tell him where the great countries of the world are, what they are,
and how they have become what they are.
Without doubt all these are most fitting and excellent things to teach a
boy; I should be very sorry to omit any of them from any scheme of
primary intellectual education. The system is excellent, so far as it
goes.
But if I regard it closely, a curious reflection arises. I suppose that,
fifteen hundred years ago, the child of any well-to-do Roman citizen was
taught just these same things; reading and writing in his own, and,
perhaps, the Greek tongue; the elements of mathematics; and the
religion, morality, history, and geography current in his time.
Furthermore, I do not think I err in affirming, that, if such a
Christian Roman boy, who had finished his education, could be
transplanted into one of our public schools, and pass through its course
of instruction, he would not meet with a single unfamiliar line of
thought; amidst all the new facts he would have to learn, not one would
suggest a different mode of regarding the universe from that current in
his own time.
And yet surely there is some great difference between the civilization
of the fourth century and that of the nineteenth, and still more between
the intellectual habits and tone of thought of that day and this?
And what has made this difference? I answer fearlessly,--The prodigious
development of physical science within the last two centuries.
Modern civilization rests upon physical science; take away her gifts to
our own country, and our position among the leading nations of the world
is gone to-morrow; for it is physical science only, that makes
intelligence and moral energy stronger than brute force.
The whole of modern thought is steeped in science; it has made its way
into the works of our best poets, and even the mere man of letters, who
affects to ignore and despise science, is unconsciously impregnated with
her spirit, and indebted for his best products to her methods. I believe
that the greatest intellectual revolution mankind has yet seen is now
slowly taking place by her agency. She is teaching the world that the
ultimate court of appeal is observation and experiment, and not
authority; she is teaching it to estimate the value of evidence; she is
creating a firm and living faith in the existence of immutable moral and
physical laws, perfect obedience to which is the highest possible aim of
an intelligent being.
But of all this your old stereotyped system of education takes no note.
Physical science, its methods, its problems, and its difficulties, will
meet the poorest boy at every turn, and yet we educate him in such a
manner that he shall enter the world as ignorant of the existence of the
methods and facts of science as the day he was born. The modern world is
full of artillery; and we turn out our children to do battle in it,
equipped with the shield and sword of an ancient gladiator.
Posterity will cry shame on us if we do not remedy this deplorable state
of things. Nay, if we live twenty years longer, our own consciences will
cry shame on us.
It is my firm conviction that the only way to remedy it is, to make the
elements of physical science an integral part of primary education. I
have endeavoured to show you how that may be done for that branch of
science which it is my business to pursue; and I can but add, that I
should look upon the day when every schoolmaster throughout this land
was a centre of genuine, however rudimentary, scientific knowledge, as
an epoch in the history of the country.
But let me entreat you to remember my last words. Addressing myself to
you, as teachers, I would say, mere book learning in physical science is
a sham and a delusion--what you teach, unless you wish to be impostors,
that you must first know; and real knowledge in science means personal
acquaintance with the facts, be they few or many.[9]
FOOTNOTE:
[9] It has been suggested to me that these words may be taken to imply a
discouragement on my part of any sort of scientific instruction which
does not give an acquaintance with the facts at first hand. But this is
not my meaning. The ideal of scientific teaching is, no doubt, a system
by which the scholar sees every fact for himself, and the teacher
supplies only the explanations. Circumstances, however, do not often
allow of the attainment of that ideal, and we must put up with the next
best system--one in which the scholar takes a good deal on trust from a
teacher, who, knowing the facts by his own knowledge, can describe them
with so much vividness as to enable his audience to form competent ideas
concerning them. The system which I repudiate is that which allows
teachers who have not come into direct contact with the leading facts of
a science to pass their second-hand information on. The scientific
virus, like vaccine lymph, if passed through too long a succession of
organisms, will lose all its effect in protecting the young against the
intellectual epidemics to which they are exposed.
VII.
ON THE PHYSICAL BASIS OF LIFE.[10]