Lectures and Essays

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Lectures and Essays

by T.H. Huxley

***

THE PEOPLE'S LIBRARY.

LECTURES AND ESSAYS.

THOMAS HENRY HUXLEY.

EDITOR'S NOTE.

Of the great thinkers of the nineteenth century, Thomas Henry Huxley,
son of an Ealing schoolmaster, was undoubtedly the most noteworthy. His
researches in biology, his contributions to scientific controversy, his
pungent criticisms of conventional beliefs and thoughts have probably
had greater influence than the work of any other English scientist. And
yet he was a "self-made" intellectualist. In spite of the fact that his
father was a schoolmaster he passed through no regular course of
education. "I had," he said, "two years of a pandemonium of a school
(between eight and ten) and after that neither help nor sympathy in any
intellectual direction till I reached manhood." When he was twelve a
craving for reading found satisfaction in Hutton's "Geology," and when
fifteen in Hamilton's "Logic."

At seventeen Huxley entered as a student at Charing Cross Hospital, and
three years later he was M.B. and the possessor of the gold medal for
anatomy and physiology. An appointment as surgeon in the navy proved to
be the entry to Huxley's great scientific career, for he was gazetted to
the "Rattlesnake", commissioned for surveying work in Torres Straits. He
was attracted by the teeming surface life of tropical seas and his study
of it was the commencement of that revolution in scientific knowledge
ultimately brought about by his researches.

Thomas Henry Huxley was born at Ealing on May 4, 1825, and died at
Eastbourne June 29, 1895.

***

LECTURES

AND

ESSAYS

BY

T.H. HUXLEY.

CASSELL AND COMPANY, LTD.
LONDON, PARIS, NEW YORK, TORONTO & MELBOURNE.
MCMVIII.

***

CONTENTS.

ON OUR KNOWLEDGE OF THE CAUSES OF THE PHENOMENA OF ORGANIC NATURE:

THE PRESENT CONDITION OF ORGANIC NATURE.

THE PAST CONDITION OF ORGANIC NATURE.

THE METHOD BY WHICH THE CAUSES OF THE PRESENT AND PAST CONDITIONS OF
ORGANIC NATURE ARE TO BE DISCOVERED.--THE ORIGINATION OF LIVING BEINGS.

THE PERPETUATION OF LIVING BEINGS, HEREDITARY TRANSMISSION AND
VARIATION.

THE CONDITIONS OF EXISTENCE AS AFFECTING THE PERPETUATION OF LIVING
BEINGS.

A CRITICAL EXAMINATION OF THE POSITION OF MR. DARWIN'S WORK, "ON THE
ORIGIN OF SPECIES," IN RELATION TO THE COMPLETE THEORY OF THE CAUSES OF
THE PHENOMENA OF ORGANIC NATURE.

ESSAYS ON DARWIN'S "ORIGIN OF SPECIES":

THE DARWINIAN HYPOTHESIS.

TIME AND LIFE.

THE ORIGIN OF SPECIES.

CRITICISMS ON "THE ORIGIN OF SPECIES".

EVIDENCE AS TO MAN'S PLACE IN NATURE:

ON THE NATURAL HISTORY OF THE MAN-LIKE APES.

ON THE RELATIONS OF MAN TO THE LOWER ANIMALS.

ON SOME FOSSIL REMAINS OF MAN.

ON THE ADVISABLENESS OF IMPROVING NATURAL KNOWLEDGE.

ON THE STUDY OF ZOOLOGY.

GEOLOGICAL CONTEMPORANEITY AND PERSISTENT TYPES OF LIFE.

CORAL AND CORAL REEFS.

YEAST.

THE CIRCULATION OF THE BLOOD.

***

ON OUR KNOWLEDGE

OF THE CAUSES OF THE PHENOMENA

OF

ORGANIC NATURE.

NOTICE TO THE FIRST EDITION.

The Publisher of these interesting Lectures, having made an arrangement
for their publication with Mr. J.A. Mays, the Reporter, begs to append
the following note from Professor Huxley:--

"Mr. J. Aldous Mays, who is taking shorthand notes of my 'Lectures to
Working Men,' has asked me to allow him, on his own account, to print
those Notes for the use of my audience. I willingly accede to this
request, on the understanding that a notice is prefixed to the effect
that I have no leisure to revise the Lectures, or to make alterations in
them, beyond the correction of any important error in a matter of fact."

***

ON OUR KNOWLEDGE OF THE CAUSES OF THE PHENOMENA OF ORGANIC NATURE:

THE PRESENT CONDITION OF ORGANIC NATURE.

When it was my duty to consider what subject I would select for the six
lectures* ([Footnote] *To Working Men, at the Museum of Practical
Geology, 1863.) which I shall now have the pleasure of delivering to
you, it occurred to me that I could not do better than endeavour to put
before you in a true light, or in what I might perhaps with more modesty
call, that which I conceive myself to be the true light, the position of
a book which has been more praised and more abused, perhaps, than any
book which has appeared for some years;--I mean Mr. Darwin's work on the
"Origin of Species". That work, I doubt not, many of you have read; for
I know the inquiring spirit which is rife among you. At any rate, all of
you will have heard of it,--some by one kind of report and some by
another kind of report; the attention of all and the curiosity of all
have been probably more or less excited on the subject of that work. All
I can do, and all I shall attempt to do, is to put before you that kind
of judgment which has been formed by a man, who, of course, is liable to
judge erroneously; but, at any rate, of one whose business and
profession it is to form judgments upon questions of this nature.

And here, as it will always happen when dealing with an extensive
subject, the greater part of my course--if, indeed, so small a number of
lectures can be properly called a course--must be devoted to preliminary
matters, or rather to a statement of those facts and of those principles
which the work itself dwells upon, and brings more or less directly
before us. I have no right to suppose that all or any of you are
naturalists; and even if you were, the misconceptions and
misunderstandings prevalent even among naturalists on these matters
would make it desirable that I should take the course I now propose to
take,--that I should start from the beginning,--that I should endeavour
to point out what is the existing state of the organic world,--that I
should point out its past condition,--that I should state what is the
precise nature of the undertaking which Mr. Darwin has taken in hand;
that I should endeavour to show you what are the only methods by which
that undertaking can be brought to an issue, and to point out to you how
far the author of the work in question has satisfied those conditions,
how far he has not satisfied them, how far they are satisfiable by man,
and how far they are not satisfiable by man.

To-night, in taking up the first part of this question, I shall
endeavour to put before you a sort of broad notion of our knowledge of
the condition of the living world. There are many ways of doing this. I
might deal with it pictorially and graphically. Following the example of
Humboldt in his "Aspects of Nature", I might endeavour to point out the
infinite variety of organic life in every mode of its existence, with
reference to the variations of climate and the like; and such an attempt
would be fraught with interest to us all; but considering the subject
before us, such a course would not be that best calculated to assist us.
In an argument of this kind we must go further and dig deeper into the
matter; we must endeavour to look into the foundations of living Nature,
if I may so say, and discover the principles involved in some of her
most secret operations. I propose, therefore, in the first place, to
take some ordinary animal with which you are all familiar, and, by
easily comprehensible and obvious examples drawn from it, to show what
are the kind of problems which living beings in general lay before us;
and I shall then show you that the same problems are laid open to us by
all kinds of living beings. But first, let me say in what sense I have
used the words "organic nature." In speaking of the causes which lead to
our present knowledge of organic nature, I have used it almost as an
equivalent of the word "living," and for this reason,--that in almost
all living beings you can distinguish several distinct portions set
apart to do particular things and work in a particular way. These are
termed "organs," and the whole together is called "organic." And as it
is universally characteristic of them, this term "organic" has been very
conveniently employed to denote the whole of living nature,--the whole
of the plant world, and the whole of the animal world.

Few animals can be more familiar to you than that whose skeleton is
shown on our diagram. You need not bother yourselves with this "Equus
caballus" written under it; that is only the Latin name of it, and does
not make it any better. It simply means the common Horse. Suppose we
wish to understand all about the Horse. Our first object must be to
study the structure of the animal. The whole of his body is inclosed
within a hide, a skin covered with hair; and if that hide or skin be
taken off, we find a great mass of flesh, or what is technically called
muscle, being the substance which by its power of contraction enables
the animal to move. These muscles move the hard parts one upon the
other, and so give that strength and power of motion which renders the
Horse so useful to us in the performance of those services in which we
employ him.

And then, on separating and removing the whole of this skin and flesh,
you have a great series of bones, hard structures, bound together with
ligaments, and forming the skeleton which is represented here.

(FIGURE 1. Section through a horse.

FIGURE 2. Section through a cell.)

In that skeleton there are a number of parts to be recognized. The long
series of bones, beginning from the skull and ending in the tail, is
called the spine, and those in front are the ribs; and then there are
two pairs of limbs, one before and one behind; and there are what we all
know as the fore-legs and the hind-legs. If we pursue our researches
into the interior of this animal, we find within the framework of the
skeleton a great cavity, or rather, I should say, two great
cavities,--one cavity beginning in the skull and running through the
neck-bones, along the spine, and ending in the tail, containing the
brain and the spinal marrow, which are extremely important organs. The
second great cavity, commencing with the mouth, contains the gullet, the
stomach, the long intestine, and all the rest of those internal
apparatus which are essential for digestion; and then in the same great
cavity, there are lodged the heart and all the great vessels going from
it; and, besides that, the organs of respiration--the lungs: and then
the kidneys, and the organs of reproduction, and so on. Let us now
endeavour to reduce this notion of a horse that we now have, to some
such kind of simple expression as can be at once, and without
difficulty, retained in the mind, apart from all minor details. If I
make a transverse section, that is, if I were to saw a dead horse
across, I should find that, if I left out the details, and supposing I
took my section through the anterior region, and through the fore-limbs,
I should have here this kind of section of the body (Figure 1). Here
would be the upper part of the animal--that great mass of bones that we
spoke of as the spine (a, Figure 1). Here I should have the alimentary
canal (b, Figure 1). Here I should have the heart (c, Figure 1); and
then you see, there would be a kind of double tube, the whole being
inclosed within the hide; the spinal marrow would be placed in the upper
tube (a, Figure 1), and in the lower tube (d d, Figure 1), there would
be the alimentary canal (b), and the heart (c); and here I shall have
the legs proceeding from each side. For simplicity's sake, I represent
them merely as stumps (e e, Figure 1). Now that is a horse--as
mathematicians would say--reduced to its most simple expression. Carry
that in your minds, if you please, as a simplified idea of the structure
of the Horse. The considerations which I have now put before you belong
to what we technically call the 'Anatomy' of the Horse. Now, suppose we
go to work upon these several parts,--flesh and hair, and skin and
bone,--and lay open these various organs with our scalpels, and examine
them by means of our magnifying-glasses, and see what we can make of
them. We shall find that the flesh is made up of bundles of strong
fibres. The brain and nerves, too, we shall find, are made up of fibres,
and these queer-looking things that are called ganglionic corpuscles. If
we take a slice of the bone and examine it, we shall find that it is
very like this diagram of a section of the bone of an ostrich, though
differing, of course, in some details; and if we take any part
whatsoever of the tissue, and examine it, we shall find it all has a
minute structure, visible only under the microscope. All these parts
constitute microscopic anatomy or 'Histology.' These parts are
constantly being changed; every part is constantly growing, decaying,
and being replaced during the life of the animal. The tissue is
constantly replaced by new material; and if you go back to the young
state of the tissue in the case of muscle, or in the case of skin, or
any of the organs I have mentioned, you will find that they all come
under the same condition. Every one of these microscopic filaments and
fibres (I now speak merely of the general character of the whole
process)--every one of these parts--could be traced down to some
modification of a tissue which can be readily divided into little
particles of fleshy matter, of that substance which is composed of the
chemical elements, carbon, hydrogen, oxygen, and nitrogen, having such a
shape as this (Figure 2). These particles, into which all primitive
tissues break up, are called cells. If I were to make a section of a
piece of the skin of my hand, I should find that it was made up of these
cells. If I examine the fibres which form the various organs of all
living animals, I should find that all of them, at one time or other,
had been formed out of a substance consisting of similar elements; so
that you see, just as we reduced the whole body in the gross to that
sort of simple expression given in Figure 1, so we may reduce the whole
of the microscopic structural elements to a form of even greater
simplicity; just as the plan of the whole body may be so represented in
a sense (Figure 1), so the primary structure of every tissue may be
represented by a mass of cells (Figure 2).

Having thus, in this sort of general way, sketched to you what I may
call, perhaps, the architecture of the body of the Horse (what we term
technically its Morphology), I must now turn to another aspect. A horse
is not a mere dead structure: it is an active, living, working machine.
Hitherto we have, as it were, been looking at a steam-engine with the
fires out, and nothing in the boiler; but the body of the living animal
is a beautifully-formed active machine, and every part has its different
work to do in the working of that machine, which is what we call its
life. The Horse, if you see him after his day's work is done, is
cropping the grass in the fields, as it may be, or munching the oats in
his stable. What is he doing? His jaws are working as a mill--and a very
complex mill too--grinding the corn, or crushing the grass to a pulp. As
soon as that operation has taken place, the food is passed down to the
stomach, and there it is mixed with the chemical fluid called the
gastric juice, a substance which has the peculiar property of making
soluble and dissolving out the nutritious matter in the grass, and
leaving behind those parts which are not nutritious; so that you have,
first, the mill, then a sort of chemical digester; and then the food,
thus partially dissolved, is carried back by the muscular contractions
of the intestines into the hinder parts of the body, while the soluble
portions are taken up into the blood. The blood is contained in a vast
system of pipes, spreading through the whole body, connected with a
force pump,--the heart,--which, by its position and by the contractions
of its valves, keeps the blood constantly circulating in one direction,
never allowing it to rest; and then, by means of this circulation of the
blood, laden as it is with the products of digestion, the skin, the
flesh, the hair, and every other part of the body, draws from it that
which it wants, and every one of these organs derives those materials
which are necessary to enable it to do its work.

The action of each of these organs, the performance of each of these
various duties, involve in their operation a continual absorption of the
matters necessary for their support, from the blood, and a constant
formation of waste products, which are returned to the blood, and
conveyed by it to the lungs and the kidneys, which are organs that have
allotted to them the office of extracting, separating, and getting rid
of these waste products; and thus the general nourishment, labour, and
repair of the whole machine is kept up with order and regularity. But
not only is it a machine which feeds and appropriates to its own support
the nourishment necessary to its existence--it is an engine for
locomotive purposes. The Horse desires to go from one place to another;
and to enable it to do this, it has those strong contractile bundles of
muscles attached to the bones of its limbs, which are put in motion by
means of a sort of telegraphic apparatus formed by the brain and the
great spinal cord running through the spine or backbone; and to this
spinal cord are attached a number of fibres termed nerves, which proceed
to all parts of the structure. By means of these the eyes, nose, tongue,
and skin--all the organs of perception--transmit impressions or
sensations to the brain, which acts as a sort of great central
telegraph-office, receiving impressions and sending messages to all
parts of the body, and putting in motion the muscles necessary to
accomplish any movement that may be desired. So that you have here an
extremely complex and beautifully-proportioned machine, with all its
parts working harmoniously together towards one common object--the
preservation of the life of the animal.

Now, note this: the Horse makes up its waste by feeding, and its food is
grass or oats, or perhaps other vegetable products; therefore, in the
long run, the source of all this complex machinery lies in the vegetable
kingdom. But where does the grass, or the oat, or any other plant,
obtain this nourishing food-producing material? At first it is a little
seed, which soon begins to draw into itself from the earth and the
surrounding air matters which in themselves contain no vital properties
whatever; it absorbs into its own substance water, an inorganic body; it
draws into its substance carbonic acid, an inorganic matter; and
ammonia, another inorganic matter, found in the air; and then, by some
wonderful chemical process, the details of which chemists do not yet
understand, though they are near foreshadowing them, it combines them
into one substance, which is known to us as 'Protein,' a complex
compound of carbon, hydrogen, oxygen, and nitrogen, which alone
possesses the property of manifesting vitality and of permanently
supporting animal life. So that, you see, the waste products of the
animal economy, the effete materials which are continually being thrown
off by all living beings, in the form of organic matters, are constantly
replaced by supplies of the necessary repairing and rebuilding materials
drawn from the plants, which in their turn manufacture them, so to
speak, by a mysterious combination of those same inorganic materials.

Let us trace out the history of the Horse in another direction. After a
certain time, as the result of sickness or disease, the effect of
accident, or the consequence of old age, sooner or later, the animal
dies. The multitudinous operations of this beautiful mechanism flag in
their performance, the Horse loses its vigour, and after passing through
the curious series of changes comprised in its formation and
preservation, it finally decays, and ends its life by going back into
that inorganic world from which all but an inappreciable fraction of its
substance was derived. Its bones become mere carbonate and phosphate of
lime; the matter of its flesh, and of its other parts, becomes, in the
long run, converted into carbonic acid, into water, and into ammonia.
You will now, perhaps, understand the curious relation of the animal
with the plant, of the organic with the inorganic world, which is shown
in this diagram (Figure 3).

(FIGURE 3. Diagram showing material relationship of the Vegetable,
Animal and Inorganic Worlds.)

The plant gathers these inorganic materials together and makes them up
into its own substance. The animal eats the plant and appropriates the
nutritious portions to its own sustenance, rejects and gets rid of the
useless matters; and, finally, the animal itself dies, and its whole
body is decomposed and returned into the inorganic world. There is thus
a constant circulation from one to the other, a continual formation of
organic life from inorganic matters, and as constant a return of the
matter of living bodies to the inorganic world; so that the materials of
which our bodies are composed are largely, in all probability, the
substances which constituted the matter of long extinct creations, but
which have in the interval constituted a part of the inorganic world.

Thus we come to the conclusion, strange at first sight, that the MATTER
constituting the living world is identical with that which forms the
inorganic world. And not less true is it that, remarkable as are the
powers or, in other words, as are the FORCES which are exerted by living
beings, yet all these forces are either identical with those which exist
in the inorganic world, or they are convertible into them; I mean in
just the same sense as the researches of physical philosophers have
shown that heat is convertible into electricity, that electricity is
convertible into magnetism, magnetism into mechanical force or chemical
force, and any one of them with the other, each being measurable in
terms of the other,--even so, I say, that great law is applicable to the
living world. Consider why is the skeleton of this horse capable of
supporting the masses of flesh and the various organs forming the living
body, unless it is because of the action of the same forces of cohesion
which combines together the particles of matter composing this piece of
chalk? What is there in the muscular contractile power of the animal but
the force which is expressible, and which is in a certain sense
convertible, into the force of gravity which it overcomes? Or, if you go
to more hidden processes, in what does the process of digestion differ
from those processes which are carried on in the laboratory of the
chemist? Even if we take the most recondite and most complex operations
of animal life--those of the nervous system, these of late years have
been shown to be--I do not say identical in any sense with the
electrical processes--but this has been shown, that they are in some way
or other associated with them; that is to say, that every amount of
nervous action is accompanied by a certain amount of electrical
disturbance in the particles of the nerves in which that nervous action
is carried on. In this way the nervous action is related to electricity
in the same way that heat is related to electricity; and the same sort
of argument which demonstrates the two latter to be related to one
another shows that the nervous forces are correlated to electricity; for
the experiments of M. Dubois Reymond and others have shown that whenever
a nerve is in a state of excitement, sending a message to the muscles or
conveying an impression to the brain, there is a disturbance of the
electrical condition of that nerve which does not exist at other times;
and there are a number of other facts and phenomena of that sort; so
that we come to the broad conclusion that not only as to living matter
itself, but as to the forces that matter exerts, there is a close
relationship between the organic and the inorganic world--the difference
between them arising from the diverse combination and disposition of
identical forces, and not from any primary diversity, so far as we can
see.

I said just now that the Horse eventually died and became converted into
the same inorganic substances from whence all but an inappreciable
fraction of its substance demonstrably originated, so that the actual
wanderings of matter are as remarkable as the transmigrations of the
soul fabled by Indian tradition. But before death has occurred, in the
one sex or the other, and in fact in both, certain products or parts of
the organism have been set free, certain parts of the organisms of the
two sexes have come into contact with one another, and from that
conjunction, from that union which then takes place, there results the
formation of a new being. At stated times the mare, from a particular
part of the interior of her body, called the ovary, gets rid of a minute
particle of matter comparable in all essential respects with that which
we called a cell a little while since, which cell contains a kind of
nucleus in its centre, surrounded by a clear space and by a viscid mass
of protein substance (Figure 2); and though it is different in
appearance from the eggs which we are mostly acquainted with, it is
really an egg. After a time this minute particle of matter, which may
only be a small fraction of a grain in weight, undergoes a series of
changes,--wonderful, complex changes. Finally, upon its surface there is
fashioned a little elevation, which afterwards becomes divided and
marked by a groove. The lateral boundaries of the groove extend upwards
and downwards, and at length give rise to a double tube. In the upper
smaller tube the spinal marrow and brain are fashioned; in the lower,
the alimentary canal and heart; and at length two pairs of buds shoot
out at the sides of the body, which are the rudiments of the limbs. In
fact a true drawing of a section of the embryo in this state would in
all essential respects resemble that diagram of a horse reduced to its
simplest expression, which I first placed before you (Figure 1).

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