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Undoubtedly the force of these reflections is not diminished when the
bituminous coal, as in Britain, consists of accumulated spores and spore-
cases, rather than of stems. But, suppose we adopt Principal Dawson's
assumption, that one foot of coal represents fifty generations of coal
plants; and, further, make the mod... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
Once more, an invariably-recurring lesson of geological history, at
whatever point its study is taken up: the lesson of the almost infinite
slowness of the modification of living forms. The lines of the pedigrees
of living things break off almost before they begin to converge.
Finally, yet another curious consideratio... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
Thus, all this abundant wealth of money and of vivid life is Nature's
interest upon her investment in club-mosses, and the like, so long ago.
But what becomes of the coal which is burnt in yielding this interest?
Heat comes out of it, light comes out of it; and if we could gather
together all that goes up the chimney,... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
Following out his teleological argument, Cuvier remarks that the
organisation of this cavity and its appurtenances must needs vary
according to the nature of the aliment, and the operations which it has
to undergo, before it can be converted into substances fitted for
absorption; while the atmosphere and the earth sup... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
Thus wrote Cuvier in 1828. But, in the fourth and fifth decades of this
century, the greatest and most rapid revolution which biological science
has ever undergone was effected by the application of the modern
microscope to the investigation of organic structure; by the introduction
of exact and easily manageable meth... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
Hence the teleological argument for Cuvier's first diagnostic character--
the presence in animals of an alimentary cavity, or internal pocket, in
which they can carry about their nutriment--has broken down, so far, at
least, as his mode of stating it goes. And, with the advance of
microscopic anatomy, the universality... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
Moreover, although it remains true that there is an inverse relation
between the green plant in sunshine and the animal, in so far as, under
these circumstances, the green plant decomposes carbonic acid and exhales
oxygen, while the animal absorbs oxygen and exhales carbonic acid; yet,
the exact researches of the mode... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
The contractility which is the fundamental condition of locomotion, has
not only been discovered to exist far more widely among plants than was
formerly imagined; but, in plants, the act of contraction has been found
to be accompanied, as Dr. Burdon Sanderson's interesting investigations
have shown, by a disturbance o... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
Thus it must be admitted that plants may be contractile and locomotive;
that, while locomotive, their movements may have as much appearance of
spontaneity as those of the lowest animals; and that many exhibit
actions, comparable to those which are brought about by the agency of a
nervous system in animals. And it must... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
The bean has been able to perform this great chemical feat by the help of
its green colouring matter, or chlorophyll; for it is only the green
parts of the plant which, under the influence of sunlight, have the
marvellous power of decomposing carbonic acid, setting free the oxygen
and laying hold of the carbon which i... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
Contrariwise, there is a no less wide foundation for the generalisation
that animals, as Cuvier puts it, depend directly or indirectly upon
plants for the materials of their bodies; that is, either they are
herbivorous, or they eat other animals which are herbivorous.
But for what constituents of their bodies are anim... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
But other active organisms, very much larger than the _Bacteria_,
attaining in fact the comparatively gigantic dimensions of 1/3000 of an
inch or more, incessantly crossed the field of view. Each of these had a
body shaped like a pear, the small end being slightly incurved and
produced into a long curved filament, or ... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
I have been unable to devote to my _Heteromita_ the prolonged study
needful to work out its whole history, which would involve weeks, or it
may be months, of unremitting attention. But I the less regret this
circumstance, as some remarkable observations recently published by
Messrs. Dallinger and Drysdale[5] on certai... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
During these processes of multiplication by fission, the _Heteromita_
remains active; but sometimes another mode of fission occurs. The body
becomes rounded and quiescent, or nearly so; and, while in this resting
state, divides into two portions, each of which is rapidly converted into
an active _Heteromita_.
A still ... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
I am not aware that the investigators from whom I have borrowed this
history have endeavoured to ascertain whether their monads take solid
nutriment or not; so that though they help us very much to fill up the
blanks in the history of my _Heteromita_, their observations throw no
light on the problem we are trying to s... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
The eminent botanist, De Bary, who was not thinking of our problem, tells
us, in describing the movements of these "Zoospores," that, as they swim
about, "Foreign bodies are carefully avoided, and the whole movement has
a deceptive likeness to the voluntary changes of place which are observed
in microscopic animals."
... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
Moreover, it would be possible to pursue the analogy farther. Under
certain circumstances, a process of conjugation takes place in the
_Peronospora_. Two separate portions of its protoplasm become fused
together, surround themselves with a thick coat and give rise to a sort
of vegetable egg called an _oospore_. After ... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
If the whole history of the zoospores of _Peronospora_ and of
_Coleochaete_ were unknown, they would undoubtedly be classed among
"Monads" with the same right as _Heteromita_; why then may not
_Heteromita_ be a plant, even though the cycle of forms through which it
passes shows no terms quite so complex as those which... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
Thus there is really no reason why _Heteromita_ may not be a plant; and
this conclusion would be very satisfactory, if it were not equally easy
to show that there is really no reason why it should not be an animal.
For there are numerous organisms presenting the closest resemblance to
_Heteromita_, and, like it, group... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
But this creature is an unmistakable animal, and full-sized _Colpodoe_
may be fed as easily as one feeds chickens. It is only needful to diffuse
very finely ground carmine through the water in which they live, and, in
a very short time, the bodies of the _Colpodoe_ are stuffed with the
deeply-coloured granules of the ... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
There is reason to think that certain organisms which pass through a
monad stage of existence, such as the _Myxomycetes_, are, at one time of
their lives, dependent upon external sources for their protein matter, or
are animals; and, at another period, manufacture it, or are plants. And
seeing that the whole progress ... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
Linnaeus was a naturalist in this wide sense, and his "Systema Naturae" was
a work upon natural history, in the broadest acceptation of the term; in
it, that great methodising spirit embodied all that was known in his time
of the distinctive characters of minerals, animals, and plants. But the
enormous stimulus which ... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
For the purpose of the present discourse, however, I shall recognise none
of these titles save the last, which I shall employ as the equivalent of
botanist, and I shall use the term zoology is denoting the whole doctrine
of animal life, in contradistinction to botany, which signifies the whole
doctrine of vegetable li... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
If I now take the fourth ring, I find it has the same structure, and so
have the fifth and the second; so that, in each of these divisions of the
tail, I find parts which correspond with one another, a ring and two
appendages; and in each appendage a stalk and two end pieces. These
corresponding parts are called, in t... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
It looks, at first, a little hopeless to attempt to find in this complex
mass a series of rings, each with its pair of appendages, such as I have
shown you in the abdomen, and yet it is not difficult to demonstrate
their existence. Strip off the legs, and you will find that each pair is
attached to a very definite seg... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
But I imagine I hear the question, How is all this to be tested? No doubt
it is a pretty and ingenious way of looking at the structure of any
animal; but is it anything more? Does Nature acknowledge, in any deeper
way, this unity of plan we seem to trace?
The objection suggested by these questions is a very valid and ... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
These are wonderful truths, the more so because the zoologist finds them
to be of universal application. The investigation of a polype, of a
snail, of a fish, of a horse, or of a man, would have led us, though by a
less easy path, perhaps, to exactly the same point. Unity of plan
everywhere lies hidden under the mask ... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
If I had worked my way from a sponge instead of a lobster, I should have
found it associated, by like ties, with a great number of other animals
into the sub-kingdom _Protozoa_; if I had selected a fresh-water polype
or a coral, the members of what naturalists term the sub-kingdom
_Coelenterata_, would have grouped th... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
In this broad sense, it may with truth be said, that all living animals,
and all those dead faunae which geology reveals, are bound together by an
all-pervading unity of organisation, of the same character, though not
equal in degree, to that which enables us to discern one and the same
plan amidst the twenty differen... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
Again, we investigated the distribution of our type in space and in time,
and, if the like had been done with every animal, the sciences of
geographical and geological distribution would have attained their limit.
But you will observe one remarkable circumstance, that, up to this point,
the question of the life of the... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
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 ... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
In the higher animals the phenomena 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... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
And if it were nay 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 _Cyanoea_, a fresh-water
mussel, a lobster, a fowl, a... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
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... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
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 ca... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
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... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
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 educ... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
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 geograph... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
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 t... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
[The remarks on p. 222 applied to the Natural History Collection of the
British Museum in 1861. The visitor to the Natural History Museum in 1894
need go no further than the Great Hall to see the realisation of my hopes
by the present Director.]]
VIII
BIOGENESIS AND ABIOGENESIS
(THE PRESIDENTIAL ADDRESS TO THE BRITIS... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
The philosophers of antiquity, interrogated as to the cause of these
phenomena, were provided with a ready and a plausible answer. It did not
enter their minds even to doubt that these low forms of life were
generated in the matters in which they made their appearance. Lucretius,
who had drunk deeper of the scientific... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
[Footnote 3: See the following passage in Exercitatio I.:--"Item _sponte
nascentia_ dicuntur; non quod ex _putredine_ oriunda sint, sed quod casu,
naturae sponte, et aequivocâ (ut aiunt) generatione, a parentibus sui
dissimilibus proveniant." Again, in _De Uteri Membranis:_--"In cunctorum
viventium generatione (sicut ... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
These experiments seem almost childishly simple, and one wonders how it
was that no one ever thought of them before. Simple as they are, however,
they are worthy of the most careful study, for every piece of
experimental work since done, in regard to this subject, has been shaped
upon the model furnished by the Italia... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
'Nonne vides quaecunque mora, fluidoque calore
Corpora tabescunt in parva animalia verti'--
Io mi sento, dico, inclinato, a credere che tutti quei vermi si generino
dal seme paterno; e che le carni, e l' erbe, e l' altre cose tutte
putrefatte, o putrefattibili non facciano altra parte, nè abbiano altro
ufizio nella ge... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
[Footnote 6: The passage (_Esperienze_, p. 129) is worth quoting in
full:--
"Se dovessi palesarvi il mio sentimento crederei che i frutti, i legumi,
gli alberi e le foglie, in due maniere inverminassero. Una, perchè
venendo i bachi per dí fuora, e cercando l' alimento, col rodere ci
aprono la strada, ed arrivano alla ... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
It is of great importance to apprehend Redi's position rightly; for the
lines of thought he laid down for us are those upon which naturalists
have been working ever since. Clearly, he held _Biogenesis_ as against
_Abiogenesis;_ and I shall immediately proceed, in the first place, to
inquire how far subsequent investig... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
"Les naturalistes modernes s'accordent unaninement à établir, comme une
vérité certaine, que toute plante vient do sa sémence spécifique, tout
animal d'un oeuf ou de quelque chose d'analogue préexistant dans la
plante, ou dans l'animal de même espèce qui l'a produit."--_Nouvelles
Observations_, p. 169.
"Les naturalist... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
Led by various theoretical considerations which I cannot now discuss, but
which looked promising enough in the lights of their time, Buffon and
Needham doubted the applicability of Redi's hypothesis to the infusorial
animalcules, and Needham very properly endeavoured to put the question to
an experimental test. He sai... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
It will be perceived that this doctrine is by no means identical with
_Abiogenesis_, with which it is often confounded. On this hypothesis, a
piece of beef, or a handful of hay, is dead only in a limited sense. The
beef is dead ox, and the hay is dead grass; but the "organic molecules"
of the beef or the hay are not d... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
[Footnote 8: See Spallanzani, _Opere_, vi. pp. 42 and 51.]
Modern Chemistry, the birth of the latter half of the eighteenth century,
grew apace, and soon found herself face to face with the great problems
which biology had vainly tried to attack without her help. The discovery
of oxygen led to the laying of the founda... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
Contemporaneously with these investigations a remarkable discovery was
made by Cagniard de la Tour. He found that common yeast is composed of a
vast accumulation of minute plants. The fermentation of must, or of wort,
in the fabrication of wine and of beer, is always accompanied by the
rapid growth and multiplication ... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
The researches of Schroeder and Dusch in 1854, and of Schroeder alone, in
1859, cleared up this point by experiments which are simply refinements
upon those of Redi. A lump of cotton-wool is, physically speaking, a pile
of many thicknesses of a very fine gauze, the fineness of the meshes of
which depends upon the clos... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
[Footnote 9: _Lectures to Working Men on the Causes of the Phenomena of
Organic Nature_, 1863. (See Vol. II. of these Essays.)]
These experiments have been repeated over and over again by independent
observers with entire success; and there is one very simple mode of
seeing the facts for one's self, which I may as wel... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
[Footnote 10: Infusion of hay treated in the same way yields similar
results; but as it contains organic matter, the argument which follows
cannot be based upon it.]
To sum up the effect of this long chain of evidence:--
It is demonstrable that a fluid eminently fit for the development of the
lowest forms of life, but... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
And in the next place, if the results of the experiments I refer to are
really trustworthy, it by no means follows that Abiogenesis has taken
place. The resistance of living matter to heat is known to vary within
considerable limits, and to depend, to some extent, upon the chemical and
physical qualities of the surrou... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
So much for the history of the progress of Redi's great doctrine of
Biogenesis, which appears to me, with the limitations I have expressed,
to be victorious along the whole line at the present day.
As regards the second problem offered to us by Redi, whether Xenogenesis
obtains, side by side with Homogenesis,--whether... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
From such innocent productions as corns and warts, there are all
gradations to the serious tumours which, by their mere size and the
mechanical obstruction they cause, destroy the organism out of which they
are developed; while, finally, in those terrible structures known as
cancers, the abnormal growth has acquired p... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
Now arises the question, are these microzymes the results of
_Homogenesis_, or of _Xenogenesis?_ are they capable, like the
_Toruloe_ of yeast, of arising only by the development of pre-existing
germs? or may they be, like the constituents of a nut-gall, the results
of a modification and individualisation of the tissu... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
The silkworm has long been known to be subject to a very fatal and
infectious disease called the _Muscardine_. Audouin transmitted it by
inoculation. This disease is entirely due to the development of a fungus,
_Botrytis Bassiana_, in the body of the caterpillar; and its
contagiousness and infectiousness are accounted... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
In 1858 the gravity of the situation caused the French Academy of
Sciences to appoint Commissioners, of whom a distinguished naturalist, M.
de Quatrefages, was one, to inquire into the nature of this disease, and,
if possible, to devise some means of staying the plague. In reading the
Report[11] made by M. de Quatrefa... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
Such being the facts with respect to the Pébrine, what are the
indications as to the method of preventing it? It is obvious that this
depends upon the way in which the _Panhistophyton_ is generated. If it
may be generated by Abiogenesis, or by Xenogenesis, within the silkworm
or its moth, the extirpation of the diseas... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
I commenced this Address by asking you to follow me in an attempt to
trace the path which has been followed by a scientific idea, in its long
and slow progress from the position of a probable hypothesis to that of
an established law of nature. Our survey has not taken us into very
attractive regions; it has lain, chie... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
And thus mankind will have one more admonition that "the people perish
for lack of knowledge"; and that the alleviation of the miseries, and the
promotion of the welfare, of men must be sought, by those who will not
lose their pains, in that diligent, patient, loving study of all the
multitudinous aspects of Nature, t... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
Were such a thought justifiable, it could hardly expect to be received
with favour by this assembly. But it is not justifiable. Your favourite
science has her own great aims independent of all others; and if,
notwithstanding her steady devotion to her own progress, she can scatter
such rich alms among her sisters, it ... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
Succession implies time; the lower members of an undisturbed series of
sedimentary rocks are certainly older than the upper; and when the notion
of age was once introduced as the equivalent of succession, it was no
wonder that correspondence in succession came to be looked upon as a
correspondence in age, or "contempo... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
It may not be unprofitable to bestow on these professions a somewhat more
critical examination than they have hitherto received, in order to
ascertain how far they rest on an irrefragable basis; or whether, after
all, it might not be well for palaeontologists to learn a little more
carefully that scientific "ars artiu... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
It is not now proposed to inquire whether these doctrines are true or
false; but to direct your attention to a much simpler though very
essential preliminary question--What is their logical basis? what are the
fundamental assumptions upon which they all logically depend? and what is
the evidence on which those fundame... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
To this there are two replies: the first that the observational basis of
the assertion that the lowest rocks are nowhere fossiliferous is an
amazingly small one, seeing how very small an area, in comparison to that
of the whole world, has yet been fully searched; the second, that the
argument is good for nothing unles... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
Is palaeontology able to succeed where physical geology fails? Standard
writers on palaeontology, as has been seen, assume that she can. They take
it for granted, that deposits containing similar organic remains are
synchronous--at any rate in a broad sense; and yet, those who will study
the eleventh and twelfth chapt... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
Now suppose that, a million or two of years hence, when Britain has made
another dip beneath the sea and has come up again, some geologist applies
this doctrine, in comparing the strata laid bare by the upheaval of the
bottom, say, of St. George's Channel with what may then remain of the
Suffolk Crag. Reasoning in the... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
For anything that geology or palaeontology are able to show to the
contrary, a Devonian fauna and flora in the British Islands may have been
contemporaneous with Silurian life in North America, and with a
Carboniferous fauna and flora in Africa. Geographical provinces and zones
may have been as distinctly marked in th... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
The preceding arguments make no particular claim to novelty; indeed they
have been floating more or less distinctly before the minds of geologists
for the last thirty years; and if, at the present time, it has seemed
desirable to give them more definite and systematic expression, it is
because palaeontology is every d... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
There are two hundred known orders of plants; of these not one is
certainly known to exist exclusively in the fossil state. The whole lapse
of geological time has as yet yielded not a single new ordinal type of
vegetable structure.[3]
[Footnote 3: See Hooker's _Introductory Essay to the Flora of Tasmania_,
p. xxiii.]
... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
Some years ago one of your Secretaries pointed out another kind of
positive palaeontological evidence tending towards the same conclusion--
afforded by the existence of what he termed "persistent types" of
vegetable and of animal life.[4] He stated, on the authority of Dr.
Hooker, that there are Carboniferous plants w... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
[Footnote 5: "Memoirs of the Geological Survey of the United Kingdom.--
Decade x. Preliminary Essay upon the Systematic Arrangement of the Fishes
of the Devonian Epoch."]
Again, what can be more remarkable than the singular constancy of
structure preserved throughout a vast period of time by the family of the
Pycnodon... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
The PROTOZOA.--The Protozoa are represented throughout the whole range of
geological series, from the Lower Silurian formation to the present day.
The most ancient forms recently made known by Ehrenberg are exceedingly
like those which now exist: no one has ever pretended that the difference
between any ancient and an... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
Or among the Teleostei--in what respect is the _Beryx_ of the Chalk more
embryonic, or less differentiated, than _Beryx lineatus_ of King George's
Sound?
Or to turn to the higher Vertebrata--in what sense are the Liassic
Chelonia inferior to those which now exist? How are the Cretaceous
Ichthyosauria, Plesiosauria, or... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
The Crinoidea, in the abundance of stalked forms in the ancient
formations as compared with their present rarity, seem to present us with
a fair case of modification from a more embryonic towards a less
embryonic condition. But then, on careful consideration of the facts, the
objection arises that the stalk, calyx, an... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
It is, in fact, true of several groups of Vertebrata which have lived
through a considerable range of time, that the endoskeleton (more
particularly the spinal column) of the older genera presents a less
ossified, and, so far, less differentiated, condition than that of the
younger genera. Thus the Devonian Ganoids, t... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
[Footnote 6: As this Address is passing through the press (March 7,
1862), evidence lies before me of the existence of a new Labyrinthodont
(_Pholidogaster_), from the Edinburgh coal-field with well-ossified
vertebral centra.]
The regularity and evenness of the dentition of the _Anoplotherium_, as
contrasted with that... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
Contrariwise, any admissible hypothesis of progressive modification must
be compatible with persistence without progression, through indefinite
periods. And should such an hypothesis eventually be proved to be true,
in the only way in which it can be demonstrated, viz. by observation and
experiment upon the existing f... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
As your attorney-general for the time being, I thought I could not do
better than get up the case with a view of advising you. It is true that
the charges brought forward by the other side involve the consideration
of matters quite foreign to the pursuits with which I am ordinarily
occupied; but, in that respect, I am... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
That great though incomplete work, "The Theory of the Earth," seems to me
to be one of the most remarkable contributions to geology which is
recorded in the annals of the science. So far as the not-living world is
concerned, uniformitarianism lies there, not only in germ, but in blossom
and fruit.
If one asks how it i... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
[Footnote 4: _Ibid._. p. 371.]
But other influences were at work upon Hutton beside those of a mind
logical by nature, and scientific by sound training; and the peculiar
turn which his speculations took seems to me to be unintelligible, unless
these be taken into account. The arguments of the French astronomers and
ma... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
"We have now considered the globe of this earth as a machine, constructed
upon chemical as well as mechanical principles, by which its different
parts are all adapted, in form, in quality, and in quantity, to a certain
end; an end attained with certainty or success; and an end from which we
may perceive wisdom, in con... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
No one can doubt that the influence of uniformitarian views has been
enormous, and, in the main, most beneficial and favourable to the
progress of sound geology.
Nor can it be questioned that Uniformitarianism has even a stronger title
than Catastrophism to call itself the geological speculation of Britain,
or, if yo... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
[Footnote 9: _Ibid._, vol. ii. p. 613.]
The limitations implied in these passages appear to me to constitute the
weakness and the logical defect of Uniformitarianism. No one will impute
blame to Hutton that, in face of the imperfect condition, in his day, of
those physical sciences which furnish the keys to the riddle... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
If I study a living being, under what heads does the knowledge I obtain
fall? I can learn its structure, or what we call its ANATOMY; and its
DEVELOPMENT, or the series of changes which it passes through to acquire
its complete structure. Then I find that the living being has certain
powers resulting from its own acti... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
All that can be ascertained concerning the structure, succession of
conditions, actions, and position in space of the earth, is the matter of
fact of its natural history. But, as in biology, there remains the matter
of reasoning from these facts to their causes, which is just as much
science as the other, and indeed m... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
The sort of geological speculation to which I am now referring
(geological aetiology, in short) was created, as a science, by that famous
philosopher Immanuel Kant, when, in 1775, he wrote his "General Natural
History and Theory of the Celestial Bodies; or an Attempt to account for
the Constitutional and the Mechanica... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
Kant's further application of his views to the earth itself is to be
found in his "Treatise on Physical Geography"[14] (a term under which the
then unknown science of geology was included), a subject which he had
studied with very great care and on which he lectured for many years. The
fourth section of the first part... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
I have said that the three schools of geological speculation which I have
termed Catastrophism, Uniformitarianism, and Evolutionism, are commonly
supposed to be antagonistic to one another; and I presume it will have
become obvious that in my belief, the last is destined to swallow up the
other two. But it is proper t... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
I do not know whether Evolutionism can claim that amount of currency
which would entitle it to be called British popular geology; but, more or
less vaguely, it is assuredly present in the minds of most geologists.
Such being the three phases of geological speculation, we are now in
position to inquire which of these i... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
The first inquiry which arises plainly is, has it ever been denied that
this period _may_ be enough for the purposes of geology?
The discussion of this question is greatly embarrassed by the vagueness
with which the assumed limit is, I will not say defined, but indicated,--
"some such period of past time as one hundre... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
Thus, if we accept the limitation of time placed before us by Sir W.
Thomson, it is not obvious, on the face of the matter, that we shall have
to alter, or reform, our ways in any appreciable degree; and we may
therefore proceed with much calmness, and indeed much indifference, as to
the result, to inquire whether tha... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
Our great astronomer, Adams, however, appears to have found a flaw in
Laplace's calculation, and to have shown that only half the observed
retardation could be accounted for in the way he had suggested. There
remains, therefore, the other half to be accounted for; and here, in the
absence of all positive knowledge, th... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
I do not presume to throw the slightest doubt upon the accuracy of any of
the calculations made by such distinguished mathematicians as those who
have made the suggestions I have cited. On the contrary, it is necessary
to my argument to assume that they are all correct. But I desire to point
out that this seems to be ... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
But, according to Sir W. Thomson's calculation, tidal retardation will
only account for a retardation of 22" in a century, or 22/100 (say 1/5)
of a second per annum.
Thus, assuming that the accumulation of polar ice since the Miocene epoch
has only been sufficient to produce ten times the effect of a coat of ice
one f... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
III. The third line of argument is based upon the temperature of the
interior of the earth. Sir W. Thomson refers to certain investigations
which prove that the present thermal condition of the interior of the
earth implies either a heating of the earth within the last 20,000 years
of as much as 100° F., or a greater ... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 | |
But is the earth nothing but a cooling mass, "like a hot-water jar such
as is used in carriages," or "a globe of sandstone," and has its cooling
been uniform? An affirmative answer to both these questions seems to be
necessary to the validity of the calculations on which Sir W. Thomson
lays so much stress.
Nevertheles... | Discourses: Biological & Geological: Essays | Huxley, Thomas Henry | 1825 | 1895 | ['en'] | 13 | {'Geology', 'Biology'} | PG10060 |
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