HUMBOLDT LIBRARY 
09 
Popular Science Literature. 
No. 36. - , NEWYORK: J. FITZGERALD & CO. [Fifteen Cents 
September, 1882. Entered at the New York Post-Office as Second-Class Matter. s'-5° per Year 
y (12 Numbers.) 
LECTURES ON EVOLUTION: 
WITH AN APPENDIX ON 
THE STUDY OF BIOLOGY, 
THOMAS H. HUXLEY. 
LECTTTEE I.* 
the universe, which,although doubt- 
less highly imperfect and inadequate 
as a picture of the great whole, is yet 
sufficient to serve him as a chart for 
the guidance of his practical affairs. 
It has taken long ages of toilsome 
and often fruitless labor to enable 
man to look steadily at the shifting 
scenes of the phantasmagoria of Na- 
ture, to notice what is fixed among 
her fluctuations, and what is regular 
among her apparent irregularities; 
and it is only comparatively lately, 
within the last few centuries, that 
the conception of a universal order 
and of a definite course of things, 
which we term the course of Na- 
ture, has emerged. 
The Three Hypotheses Respecting 
the History of Nature. 
"We live in and form part of a sys- 
tem of things of immense diversity 
and perplexity,which we call Nature; 
and it is a matter of the deepest in- 
terest to all of us that we should form 
just conceptions of the constitution 
of that system and of its past history. 
With relation to this universe,man is 
in extent, little more than a mathe- 
matical point; in duration but a fleet- 
ing shadow; he is a mere reed, shaken 
in the winds of force. But, as Pascal 
long ago remarked, although a mere 
reed, he is a thinking reed; and in 
virtue of that wonderful capacity of 
thought,he has the power of framing 
for himself a symbolic conception of 
But, once originated, the concep- 
tion of the constancy of the order of 
Nature has become the dominant 
idea of modern thought. To persona 
familiar with the facts upon which 
that conception is based, and com- 
petent to estimate their significance, 
it has ceased to be conceivable that 
•These Lectures were delivered in 
New York Sept. 18, 20,22, 1876. 2 
LECTURES ON EVOLUTION. 
chance should have any place in the 
universe, or that events should de- 
pend upon any but the natural se- 
quence of cause and effect. We have 
come to look upon the present as the 
child of the past and as the parent of 
the future; and, as we have excluded 
chance from a place in the universe, 
so we ignore, even as a possibility, 
the notion of any interference with 
the order of nature. Whatever may 
be men’s speculative doctrines, it is 
quite certain that every intelligent 
person guides his life and risks his 
fortune upon! i belief that the order 
of nature is constant, and that the 
chain of natural causation is never 
broken. 
the admission of such possibilities de- 
mands a great deal of evidence be« 
fore it recognizes them to be any- 
| thing more substantial. And when 
it is asserted that, so many thousand 
I years ago, events occurred in a mau- 
| ner utterly foreign to and inconsistent 
with the existing laws of Nature, men, 
who without being particularly cau- 
tious, are simply honest thinkers, un- 
willing to deceive themselves or de- 
lude others, ask for trustworthy evi- 
dence of the fact. 
Did things so happen or did they 
not? This is a historical question, 
and one the answer to which must be 
sought in the same way as the solu- 
tion of any other historical problem. 
So far as I know, there are only 
three hypotheses which ever have 
been entertained, or which well can 
be entertained, respecting the past 
history of Nature. I will, in the first 
place, state the hypotheses, and then 
X will consider what evidence bearing 
upon them is in our possession, and 
by what light of criticism that evi- 
dence is to be interpreted. 
In fact, no belief which we enter- 
tain has bo complete a logical basis as 
that to which I have just referred. 
It tacitly underlies every process of 
reasoning; it is the foundation of 
every act of the will. It is based 
upon the broadest induction, and it 
is verified by the most constant, reg- 
ular, and universal of deductive pro- 
cesses. But we must recollect that 
any human belief, however broad its 
basis, however defensible it may 
seem, is, after all, only a probable 
belief, and that our widest and safest 
generalizations are simply statements 
of the highest degree of probability. 
Though we are quite clear about the 
constancy of the order of Nature, at 
the present time, and in the present 
state of things, it by no means neces- 
sarily follows that we are justified in 
expanding this generalization into the 
infinite past, and in denying, abso- 
lutely, that there may have been a 
time when Nature did not fodow a 
fixed order, when the relations of 
cause and effect were not definite, 
and when extra-natural agencies in- 
terfered with the general course of 
Nature. Cautious men will allow that 
a universe so different from that which 
we know may have existed; just as a 
very candid thinker may admit that a 
world in which two and two do not 
make four, and in which two straight 
lines do enclose a space, may exist. 
Bat the same caution which forces 
Upon the first hypothesis, the as- 
sumption is, that phenomena of Na- 
tuie similar to those exhibited by the 
present world have always existed; 
in other words, that the universe has 
existed from all eternity in what may 
be broadly termed its present con- 
dition. 
The second hypothesis is, that the 
present state of things has had only 
a limited duration; and that, at some 
period in the past, a condition of the 
world, essentially similar to that 
which we now know, came into exist- 
ence, without any precedent condi- 
tion from which it would have 
naturally proceeded. The assump- 
tion that successive states of Nature 
have arisen, each without any rela- 
tion of natural causation to an ante- 
cedent state, is a mere modification 
of this second hypothesis. 
The third hypothesis also assumes 
that the present state of things has had 
but a limited duration; but it sup- 
poses that this stare has beers evolved 
by r natural process fr<wi> m LECTURES ON EVOLUTION. 
dent state, and that from another, 
and so on; and, on this hypothesis, 
the attempt to assign any limit to 
the series of past changes is, usually, 
given up. 
] account the internal forces of the 
I earth, which, upheaving the sea-bot- j 
! tom, give rise to newl and, he thought 
that these operations of degradation 
and elevation might compensate each 
other; and that thus, for any assign- 
able time, the general features of our 
planet might remain what they are. 
Ana inasmuch as, under these circum- 
stances, there need be no limit to the 
propagation of animals and plants, it 
is clear that the consistent working- 
out of the uniformitarian idea might 
lead to the conception of the eternity 
of the world. Not that I mean to 
say that either Hutton or Lyell held 
this conception—assuredly not; they 
would have been the first to repu- 
diate it. Nevertheless, the logical 
development of their arguments tends 
directly towards this hypothesis. 
It is so needful to form clear and 
distinct notions of what is really 
meant by each of these hypotheses 
that 1 will ask you to imagine wnat, 
according to each, would have been 
visible to a spectator of the events 
which constitute the history of the 
earth. On the first hypothesis, how- 
ever far back in time that spectator 
might be placed, he would see a world 
essentially, though perhaps-hot in all 
its details, similar to that which now 
exists. The animals which existed 
would be the ancestors of those 
which now live, and similar to them; 
the plants, in like manner, would be 
such as we know; and the mountains, 
plains, and waters would foreshadow 
the salient features of our present 
land and water. This view was held 
more or less distinctly, sometimes 
combined with the notion of recur- 
rent cycles of change, in ancient 
times; and its influence has been 
felt down to the present day. It is 
worthy of remark that it is a hypo- 
thesis which is not inconsistent with 
the doctrine of Uniformitarianism, 
with which geologists are familiar. 
The doctrine was held by Hutton, 
and in his earlier days by Lyell. 
Hutton was struck by the demonstra- 
tion of astronomers that the pertur- 
bations of the planetary bodies, how- 
ever great they may be, yet sooner 
or later right themselves; and that 
the solar system possesses a self-ad- 
justing power by which these aberra- 
tions are all brought back to a mean 
condition. Hutton imagined that the 
like might be true of terrestrial 
changes; although no one recognized 
more clearly than he the fact that the 
dry land is being constantly washed 
down by rain and rivers and deposit- 
ed in the sea; and that thus, in a | 
longer or shorter time, the inequali- 
ties of the earth’s surface must be 
levelled, and its high lands brought 
down tc the ocean. But, taking into 
The second hypothesis supposes 
that the present order of things, at 
some no very remote time, had a 
sudden origin, and that the world, 
such as it now is, had chaos for its 
phenomenal antecedent. That is the 
doctrine which you will find stated 
most fully and clearly in the immor- 
tal poem of John Milton—the English 
Divina Comrnedia—Paradise Post. 
I believe it is largely to the influence 
of that remarkable work, combined 
with the daily teachings to which we 
have all listened in our childhood, 
that this hypothesis owes its general 
wide diffusion as one of the current 
beliefs of English-speaking people. 
If you turn to the seventh of 
Paradise Post, you will find there 
stated the hypothesis to which I re- 
fer, which is briefly this: That this 
visible universe of ours came into 
existence at no great distance of time 
from the present; and that the parts; 
of which it is composed made their 
appearance, in a certain definite or- 
der, in the space of six natural days, 
in such a manner that, on the first of 
these days, light7 appeared; that, on 
the second, the firmament, or sky, 
separated the waters above from the 
waters beneath the firmament; that, 
on the third day, the waters drew 
away from the dry land, and upon it 4 
LECTURES ON EVOLUTION. 
% varied vegetable life, similar to that 
which now exists, made its appear- 
ance ; that the fourth day was sig- 
nalized by the apparition of the sun, 
the stars, the moon, and the planets ; 
that, on the fifth day, aquatic ani- 
mals originated within the waters ; 
that, on the sixth day, the earth gave 
rise to our four-footed terrestrial 
creatures, and to all varieties of ter- 
restrial animals except birds, which 
had appeared on the preceding day ; 
and, finally, that man appeared upon 
the earth, and the emergence of the 
universe from chaos was finished. 
Milton tells us, without the least 
ambiguity, what a spectator of these 
marvelous occurrences would have 
witnessed. I doubt not that his 
poem is familiar to all ot you, but I 
should like to recall one passage to 
your minds, in order that I may 
be justified in what I have said re- 
garding the perfectly concrete, defi- 
nite picture of the origin of the 
animal world which Miltoa draws. 
He says:— 
And rampant shakes his brinaed mane • 
the ounce, 
The libbard, and the tiger, as the mole 
Rising, the crumbled earth above them 
threw 
In hillocks, the swift stag from under- 
ground 
Bore up his branching head ; scarce from 
his mould 
Behemoth, biggest born of earth, up- 
heaved 
His vastness(; fleeted the flocks and 
bleating rose 
As plants; ambiguous between sea and 
land, 
The river-horse and scaly crocodile. 
At once came forth whatever creeps the 
ground, 
Insect or worm.” 
. There is no doubt as to the mean- 
ing of this statement, nor as to what 
a man of Milton’s genius expected 
would have been actually visible to an 
eye-witness of this mode of origina- 
tion of living things. 
The third hypothesis, or the hypo- 
thesis of evolution, supposes that, at 
any comparatively late period of past 
time, our imaginary spectator would 
meet with a state of things very simi- 
lar to that which now obtains ; but 
that the likeness of the past to the 
present would gradually become less 
and less, in proportion to the remote- 
ness of his period of observation from 
the present day; that the existing 
distribution of mountains and plains, 
of rivers and seas, would show itself 
to be the product of a slow process of 
natural change operating upon more 
and more widely different antecedent 
conditions of the mineral framework 
of the earth ; until, at length, in place 
of that framework, he would behold 
only a vast nebulous mass, represent- 
ing the constituents of the sun and of 
the planetary bodies. Preceding the 
forms of life which now exist, our ob- 
server would see animals and plants 
not identical with them, but like 
them; increasing their differences 
with their antiquity, and, at the same 
time, becoming simpler and simpler ; 
until, finally, the world of life would 
present nothing but that undifferen- 
, tiated protoplasmic matter which, so 
“ The sixth, and of creation last, arose 
With evening harps and matin, when 
Goo said, j 
1 Let the earth bring forth soul living in ' 
her kind, j 
Cattle and creeping things, and beast of 
the earth, I 
Each in their kind I’ The earth obeyed, 
and, straight 
Opening her tertile womb, teemed at a; 
birth 
Innumerous living creatures, perfect i 
forms, 
Limbed and full-grown. Out of the 
ground uprose, 
'AB from his lair, the wilu beast, where 
he wons 
In forest wild, in thicket, brake or den; 
Among the trees in pairs they rose, they 
walked; 
The cattle in the fields and meadows 
green; 
Those rare and solitary ; these in flocks 
Pasturing at once, and in broad herds up- 
sprung. 
The grassy clods now calved ; now half 
appears 
The tawny lion, pawing to get free 
His hinder parts—then springs, aa broke 
from bojudjj LECTURES ON EVOLUTION. 
5 
far as our present knowledge goes, is 
the common foundation of all vital 
activity. 
The hypothesis of evolution sup- 
poses that in all this vast progression 
there would be no breach of continu- 
ity, no point at which we could say 
“ This a natural process,” and “ This 
is not a natural process;” but that the 
whole might be compared to that 
wonderful process of development 
which may be seen going on every day 
under our eyes, in virtue of which 
there arises, out of the semi-fluid, 
comparatively homogeneous sub- 
stance which we call an egg, the com- 
plicated organization of one of the 
higher animals. That, in a few words, 
is what is meant by the hypothesis of 
evolution. 
Suppose that a man tells you that 
he saw a person strike another and 
kill him; that is testimonial evidence 
of the fact of murder. But it is pos- 
sible to have circumstantial evidence 
of the fact of murder; that is to say, 
you may find a man dying with a 
wound upon his head having exactly 
the form and character of the wound 
which is made by an axe, and, with 
due care in taking surrounding cir- 
cumstances in;o account, you may 
conclude with the utmost certainty 
that the man has been murdered; that 
his death is the consequence of a blow 
inflicted by another man with that 
inplement. We are very much in 
the habit of considering circumstan- 
tial evidence as of less value than tes- 
timonial evidence, and it may be that, 
where the circumstances are not per- 
fectly clear and intelligible, it is a 
dangerous and unsafe kind of evi- 
dence; but it must not be forgotten 
that, in many cases, circumstantial 
is quite as conclusive as testimonial 
evidence, and that, not unfrequently, 
it is a great deal weightier than testi- 
monial evidence. For example, tak« 
the case to which I referred just now. 
The circumstantial evidence may be 
better and more convincing than the 
testimonial evidence ; for it may be 
impossible, under the conditions that 
I have defined, to suppose, that the 
man met his death from any other 
cause but the violent blow of an axe, 
wielded by another man. The cir- 
cumstantial evidence in favor of a 
murder having been committed, in 
that case, is as complete and as con- 
vincing as evidence can be. It is evi- 
dence which is open to no doubt and 
to no falsification. But the testimo- 
ny of a witness is open to multitudi- 
nous doubts. He may have been 
mistaken. He may have been actua- 
ted by malice. It has constantly hap- 
pened that even an accurate man has 
declared that a thing has in 
this, that, or the other way, when a 
careful analysis of the circumstantial 
evidence has shown that it did not 
happen in that way, but in some othw 
way. 
I have already suggested that in 
dealing with these three hypotheses, 
in endeavoring to form a judgment 
as to which of them is the more 
worthy of belief, or whether none is 
worthy of belief—in which case our 
condition of mind should be that sus- 
pension of judgment which is so diffi- 
cult to all but trained intellects—we 
should be indifferent to all a priori 
considerations. The question is a 
question of historical fact. The uni- 
verse has come into existence some- 
how or other, and the problem is, 
whether it came into existence in one 
fashion, or whether it came into exis- 
tence in another; and as an essential 
preliminary to further discussion, per- 
mit me to say two or three words as 
to the nature and the kinds of histori- 
cal evidence. 
The evidence as to the occurrence 
of any event in past time may be 
ranged under two heads which, for 
convenience’s sake, I will speak of as 
testimonial evidence and as circum- 
stantial evidence. By testimonial 
evidence I mean human testimony, 
and by circumstantial evidence I 
mean evidence which is not human 
testimony. Let me illustrate by a 
familiar example what I understand 
by these two kinds of evidence, and 
what is to be said respecting their 
value. LECTURES ON EVOLUTION. 
We may now consider the evidence 
in favor of or against the three hy- 
potheses. Let me first direct your 
attention to what is to be said about 
the hypothesis of the eternity of the 
state of things in which we now 
live.- What will first strike you is, 
that it is a hypothesis which, whether 
true or false, is not capable of veri- 
fication by any evidence. For, in 
order to obtain either circumstantial 
or testimonial evidence sufficient to 
prove the eternity of duration of the 
present state of nature, you must 
have an eternity of witnesses or an 
affinity of circumstances, and neither 
of these is attainable. It is utterly 
impossible that such evidence should 
be carried beyond a certain point of 
time; and all that could be said, at 
most, would be, that so far as the 
evidence could be traced, there was 
nothing to contradict the hypothe- 
sis. But when you rook, not to the 
testimonial evidence—which, consid- 
ering the relative insignificance of 
the antiquity of human records, 
might not be good for much in this 
case—but to the circumstantial evi- 
dence, then you find that this hypo- 
thesis is absolutely incompatible with 
such evidence as we have; which is 
of so plain and simple a character 
that it is impossible in any way to 
escape from the conclusions which 
it forces upon us. 
face of the earth. For example, the 
chalk, which constitutes a great part 
of the Cretaceous formation in some 
parts of the world, is practically 
identical in its physical and chemi- 
cal characters with a substance 
which is now being formed at the 
bottom of the Atlantic Ocean, and 
covers an enormous area ; other beds 
of rock are comparable with the 
sands which are being formed upon 
ses-shores, packed together, and so 
on. Thus, omitting rocks of igneous 
origin, it is demonstrable that all 
these beds of stone, of which a total 
of not less than seventy thousand 
feet is known, have been formed by 
natural agencies, either out of the 
waste and washing of the dry land, 
or else by the accumulation of the 
exuvhe*of plants and animals. Many 
of these strata are full of such exu- 
viae—the so called “fossils.” Re- 
mains of thousand of species of 
animals and plants, as perfectly re- 
cognizable as those of existing forms 
of life which you meet with in muse- 
ums, or as the shells which you pick 
up upon the sea-beech, have been im- 
bedded in the ancient sands, or muds, 
or limestones, just as they are being 
imbedded now, in sandy, or clayey, 
or calcareous subaqueous deposits. 
They furnish us with a record, the 
general nature of which cannot be 
misinterpreted, of the kinds of things 
that have lived upon the surface of 
the earth during the time that is 
registered by this great thickness of 
stratified rocks. But even a superfi- 
cial study of these fossils shows us 
that the animals and plants which 
live at the present time h -ve had only 
a temporary duration; for the re- 
mains of such modern forms of life 
are met with, for the most part, only 
in the uppermc t or latest tertiaries, 
and their number rapidly diminishes 
in the lower deposits of that epoch. 
In the older tertiaries, the places of 
existing animals and plants are taken 
by other forms, as numerous and 
diversified as those which live now in 
the same localities, but more or less 
different from them ; in the mesozoio 
You are, doubtless, all aware that 
the outer substance of the earth, which 
alone is accessible to direct observa- 
tion, is not of a homeogeneous char- 
acter, but that it is made up of a 
number of layers or strata, the titles 
of the principal groups of which 
are placed upon the accompanying 
diagram. Each of these groups rep- 
resents a number of beds of sand, 
of stone, of clay, of slate, and of 
various other materials. 
On careful examination, it is found 
that the materials of which each of 
these layers of more or less hard 
rock are composed are, for the most 
part, of the same nature as those 
which are at-present being formed 
under known conditions on the sur- LECTURES ON EVOLUTION. 
TBRTIARY 
AND QUATERNARY 
OR 
CAINOZOIC 
'Post-Tertiary and Recent. 
Pliocene. 
Miocene. 
Eocene. 
F —Cretaceous. 
SECONDARY 
OK 
MESOZOIC 
Jurassic or Oolitic. 
Triaseic (New lied Sandstcme). 
Permian. 
Carboniferous. 
Devonian or Old Red Sandstona. 
PRIMARY 
OR 
PALAEOZOIC 
Silurian. 
Cambrian. 
Huronian. 
Laurentian. 
Fig. I.—ldeal Section of the Crust of the Earth. 
rocke, these are replaced by others 
yet more divergent from modern 
types; and in the palaeozoic forma- 
tions the contrast is still more 
marked. Thus the circumstantial 
evidence absolutely negatives the 
conception of the eternity of the pre- 
sent condition of things. We can 
say with certainty that the present 
condition of things has existed for a 
comparatively short period ; and 
that, so far as animal and vegetable 
nature are concerned, it has been pre- 
ceded by a different condition. We 
can pursue this evidence until we 
reach the lowest of the stratified 
rocks, in which we lose the indica- 
tions of life altogether. The hypo- 
thesis of the eternity of the present 
state of nature may therefore be put 
out of court. 
We now come to what I will term 
Milton’s hypothesis—the hypothesis 
that the present condition of th'ngs 
has endured for a comparatively 
short time ; and, at the commence- 
ment of that time, came into exist- 
ence within the course of six days. LECTURES ON EVOLUTION. 
I doubt not that it may have excited 
some surprise in your minds that I 
should have spoken of this as Mil- 
ton’s hypothesis, rather than that I 
should have chosen the terms which 
are more customary, such as “ the 
doctrine of creation,” or “ the Bibli- 
’cal doctrine,” or “the doctrine of 
Moses,” all of which denominations, 
as applied to the hypothesis to which 
I have just referred, are certainly 
much more familar to you than the 
title of the Miltonic hypothesis. But 
I have had what I cannot but think 
are very weighty reasons for taking 
the course which I have pursued. 
In the first place, I have discarded 
the title of the “ doctrine of creation,” 
because my present business is not 
with the question why the objects 
which constitute Nature came into 
existence, but when they came into 
existence, and in what order. This 
is as strictly a historical question as 
the question when the Angles and the 
Jutes invaded England, and whether 
they preceded or followed the Ro- 
mans. But the question about crea 
tion is a philosophical problem, and 
one which cannot be solved, or even 
approached, by the historical method. 
What we want to learn is,whetherthe 
facts, so far as they are known, af- 
ford evidence that things arose in the 
way described by Milton, or whether 
they do not; and, when that question 
is settled, it will be time enough to 
inquire into the causes of their origi- 
nation. 
to say what the Hebrew text does, 
and what it does not signify; more- 
over, were I to affirm that this is the 
Biblical doctrine, I should be met by 
the authority of many eminent schol- 
ars, to say nothing of men of science, 
who, at various times, have absolute- 
ly denied that any such doctrine is 
to be found in Genesis. If we are to 
listen to many expositors of no mean 
authority, we must believe ,that what 
seems so clearly defined in Genesis—as 
if very great pains had been taken that 
there should be no possibility of mis • 
take—is not the meaning of the text 
at all. The account is divided into pe- 
riods that we may make just as long or 
as short as convenience requires. \Ve 
are also to understand that it is con- 
sistent with the original text to be- 
lieve that the most complex plants 
and animals may have been evolved 
by natural processes, lasting for mil- 
lions of years, out of structureless 
rudiments. A person who is not a 
Hebrew scholar can only stand aside 
and admire the marvelous flexibility 
of a language which admits of such 
diverse interpretations. But as- 
suredly, in the face of such contradic- 
tions of authority upon matters re- 
specting which he is incompetent to 
form any judgment, he will abstain, 
as I do, from giving any opinion. 
In the third place, I have carefully 
abstained from speaking of this as 
the Mosaic doctrine, because we are 
now assured upon the authority of 
the highest critics, and even of dig- 
nitaries of the Church, that there is 
no evidence that Moses wrjte the 
Book of Genesis, or knew anything 
about it. You will understand that 
I give no judgment— it would be an 
impertinence upon my part to vol- 
unteer even a suggestion—upon such 
a subject. But, that being the state 
of opinion among the scholars and the 
clergy, it is well for the unlearned in 
Hebrew lore, and for the laity, to 
avoid entangling themselves in such 
a vexed question. Happily, Milton 
leaves us no excuse for doubting what 
he means, and I shall therefore be 
safe in speaking of the opinion ia 
In the second place, I have not 
spoken of this doctrine as the Bibli- 
cal doctrine. It is quite true that 
persons as diverse in their general 
views as Milton the Protestant and 
the celebrated Jesuit Father Saurez, 
each put upon the first chapter of 
Genesis the interpretation embodied 
in Milton’s poem. It is quite true 
that this .interpretation is that which 
has been instilled icto every one of us 
in our childhood ; but I do not for 
one moment venture to say that it can 
properly be called the Biblical doc- 
trine. It is not my business, and 
does not lie within my competency, LECTUEES ON EVOLUTION. 
9 
question as the Miltonic hypothesis. 
Now we have to test that hypo- 
thesis. For my part I have no pre- 
judice one way or the other. If there 
is evidence in favor of this view, I 
am burdened by no theox-etical diffi- 
culties in the way of accepting it; 
but there must be evidence. Scientific 
men get an awkward habit—no, I 
won’t call it that, for it is a valuable 
habit—of believing nothing unless 
there is evidence for it; and they 
have a way of looking upon belief 
which is not based upon evidence, 
not only as illogical, but as immoral. 
We will, if you please, test this view 
by the circumstantial evidence alone; 
for, fx-om what I have said, you will 
understand that I do not propose to 
discuss the question of what testi- 
monial evidence is to be adduced in 
favor of it. If those whose business 
it is to judge are not at one as to the 
authenticity of the only evidence of 
that kind which is offered, nor as to 
the facts to which it bears witness, 
the discussion of such evidence in su- 
perfluous. 
have no record, nor any ground for 
supposition that such an occurrence 
has taken place; or else they 
arisen by a process of evolution from 
the original stocks. 
In the second place, it is clear that 
there was no animal life before the 
fifth day, and that, on the fifth day, 
aquatic animsd and birds appeared. 
And it is further clear that terrestrial 
living things, other than birds, mads 
their appearance upon the sixth day, 
and not before. Hence, it follows 
that, if, in the large mass of circum- 
stantial evidence as to what really has 
happened in the past history of the 
globe we find indica ions of the ex- 
istence of terrestrial animals, other 
than birds, at a certain period, it is 
perfectly certain that all that has 
taken place since that time must be 
referred to the sixth day. 
In the great Carboniferous forma- 
tion, whence America derives so vast 
a proportion of her actual and poten- 
tial wealth, in the beds of coal which 
have been formed from the vegeta- 
tion of that period, we find abun- 
dant evidence of the existence of 
terrestrial animals. They have 
been described, not only by Euro- 
pean but by your own naturalists. 
There are to be found numerous 
insects allied to our cockroaches. 
There are to be found spiders and 
scorpions of large size, the latter so 
similar to existing scorpions that it 
requires the practiced eye of the 
naturalist to distinguish them. Inas- 
much as these animals can be proved 
to have been alive in the Carbonifer- 
ous epoch, it is perfectly clear that, if 
the Miltonic account is to be accepted, 
the huge mass of rocks extending from 
the middle of the Paheozoic forma- 
tions to the uppei-most members of 
the series, must belong to the day 
which is termed by Milton as the 
sixth. But, further, it is expressly 
stated that acquatic animals took their 
origin upon the fifth day, and not be- 
fore ; hence, all formations in which 
remains of acquatic animals can be 
proved to exist, and which therefore 
testify that such animals lived at the 
But I may be permitted to regret 
this necessity of rejecting the testi- 
monial evidence the less, because the 
examination of the circumstantial 
evidence leads to the conclusion, not 
only that it is incompetent to justify 
the hypothesis, but that, so far as it 
goes, it is contrary to the hypothesis. 
The considerations upon which 1 
base this conclusion are of the sim- 
plest possible character. The Mil- 
tonic hypothesis contains assertions 
of a very definite character relating 
to the succession of living forms. It 
is stated that plants, for example, 
made their appearance upon the third 
day, and not before. And you will 
understand that what the poet means 
by plants are such plants as now live, 
the aixcestors, in the ordinary way of 
propagation of like by like, of the 
trees and shrubs which flourish in the 
present tvorld. It must needs be so; 
for, if they were different, either the 
existing plants have been the result 
of a separate origination since that 
d(ascribed by Milton, of which we 10 
LECTURES ON EVOLUTION. 
time when these formations were in 
©curse of deposition, must kave been 
deposited during or since the period 
which Milton speaks of as the fifth 
day. But there is absolutely no fossil- 
iferous formation in which the re- 
mains of aquatic animals are absent. 
The oldest fossils in the Silurian rocks 
are exuviae of marine animals ; and if 
the view which is entertained by 
Principal Dawson and Dr. Carpenter 
respecting the nature of the Eozoon 
be well founded, aquatic animals ex- 
isted at a period as far antecedent to 
the deposition of the coal as the coal 
is from us ; inasmuch as the Eozoon 
is met with in those Laurentian strata 
which lie at the bottom of the series 
of stratified rocks. Hence it follows, 
plainly enough, that the whole series 
of stratified rocks, if they are to be 
brought into harmony with Milton, 
must be referred to the fifth and sixth 
days, and that we cannot hope to find 
the slightest trace of the products of 
the earlier days in the geological re- 
cord. When we consider these simple 
facts, we see how absolutely futile are 
the attempts that have been made to 
draw a parallel between the story told 
by so much of the crust of the earth 
as is known to us and the story which 
Milton tells. The whole series of 
fossiliferous stratified rocks must be 
referred to the last two days: and 
neither the Carboniferous, nor any 
other, formation can afford evidence 
of the work of the third day. 
animals, as we have just seen, occur 
in the Carboniferous rocks. 
If there were any harmony between 
the Miltonic account and the circum- 
stantial evidence, we ought to have 
abundant evidence of the existence of 
birds in the Carboniferous, the Devo- 
nian, and the Silurian rock,<. I need 
hardly say that this is not the case, 
and that not a trace of birds makes 
its appearance until the far later pe- 
riod which I have mentioned. 
And again, if it be true that all 
varieties of fishes and the great whales, 
and the like, made their appearance 
on the fifth day, we ought to find the 
remains of these animals in the older 
rocks—in those which were deposited 
before the Carboniferous epoch. 
Fishes we do find, in considerable 
number and variety ; but the great 
whales are absent, and the fishes are 
not such as now live. Not one soli- 
tary species of fish now in existence 
is to be found in the Devonian or 
Silurian formations. Hence we are 
introduced afresh to the dilemma 
which I have already placed before 
you: either the animals which came 
into existence on the fifth day were 
not such as those which are found at 
present, are not the direct and imme- 
diate ancestors of those which now 
exist; in which case either fresh 
creations of which nothing is said; 
or a process of evolution must have 
occurred ; or else the whole story 
must be given up, as not only devoid 
of any circumstantial evidence, but 
contrary to such evidence as exists. 
I placed before you in a few words, 
some little time ago, a statement of 
the sum and substance of Milton’s 
hypothesis. Let me now try to state 
as briefly, the effect of the circum- 
stantial evidence bearing upon the 
past history of the earth which is 
furnished, without the possibility of 
mistake, with no chance of error as 
to its chief features, by the stratified 
rocks. What we find is, that the 
great series of formations represents 
a period of time of which our human 
chronologies hardly afford us a unit 
of measure. I will not pretend to say 
Not only is there this objection to 
any attempt to establish a harmony 
between the Miltonic account and the 
facts recorded in the fossileferous 
rocks, but there is a further difficulty. 
According to the Miltonic account, 
the order in which animals should 
have made their appearance in the 
stratified rocks would be this: Fishes, 
including the great whales, and birds ; 
after them, all varieties of terrestrial 
animals except birds. Nothing could 
be further from the facts as we find 
them ; we know of not the slightest 
evidence of the existence of birds be- 
fore the Jurassic, or perhaps the 
Triaseio, formation ; while terrestrial LECTURES ON EVOLUTION. 
how we ought to estimate this time, 
in millions or in billions of years. 
For my purpose, the determination of 
its absolute duration is wholly unes- 
sential. But that the time Avas enor- 
mous there can be no question. 
formerly appeared to exist between 
the different formations have been 
filled up. That there is no absolute 
break between formation and forma- 
tion, that there has been no sudden 
disappearance of all the forms of 
life and replacement of them by 
others, but that changes have gone 
on slowly and gradually, that one 
type has died out and another has 
taken its place, and that thus, by in- 
sensible degrees, one fauna has been 
replaced by another, are conclusions 
strengthened by constantly increasing 
evidence. So that within the whole 
of the immense period indicated by 
the fossiliferous stratified rocks, there 
is assuredly not the slightest proof of 
any break in the uniformity of N ature’s 
operations, no indication that events 
have followed other than a clear and 
orderly sequence. 
It results from the simplest methods 
of interpretation, that leaving out of 
view certain patches of metamor- 
phosed rocks, and certain volcanic 
products, all that is now dry land has 
once been at the bottom of the waters. 
It is perfectly certain that, at a com- 
paratively recent period of the world’s 
history—the Cretaceous epoch—none 
of the great physical features which 
at present mark the surface of the 
globe existed. It is certain that the 
Rocky Mountains were not. It is 
certain that the Himalaya Mountains 
were not. It is certain that the Alps 
and the Pyrenees had no existence. 
The evidence is of the plainest pos- 
sible character; and is simply this: 
We find raised up on the hanks of 
these mountains, elevated by the 
forces of upheaval which have given 
rise to them, masses of Cretaceous 
rock which formed the bottom of the 
sea before those mountains existed. 
It is therefore clear that the elevatory 
forces which gave rise to the moan 
tains operated subsequently to the 
Cretaceous epoch; and that the 
mountains themselves are largely 
made up of the materials deposited 
in the sea which once occupied their 
place. As we go back in time, we 
meet with constant alternations of 
sea and land, of estuary and open 
ocean; and, in correspondence with 
these alterations, we observe the 
changes in the fauna and flora to 
which I have referred. 
But the inspection of these changes 
give us no right to believe that there 
has been any discontinuity in natural 
processes. There is no trace of gen- 
eral cataclysms, of universal deluges, 
or sudden destructions of a whole 
fauna or flora. The appearances 
which were formerly interpreted in 
that way have all been shown to be 
delusive, as our knowledge has in- 
creased and as the blanks which 
That, I say, is the natural and ob- 
vious teaching of the circumstantial 
evidence contained in the stratified 
rocks. 1 leave you to consider how- 
far, by an ingenuity of interpretation, 
by any stretchh gof the meaning of 
language, it can be brought into har- 
mony with the Miltonic hypothesis. 
There remains the third hypothesis, 
that of which I have spoken as the 
hypothesis of evolution ; and I pur- 
pose that in lectures to come, we 
should discuss it as carefully as we 
have considered the other two hypo- 
theses. I need not say that it is quite 
hopeless to look for testimonial evi- 
dence of evolution. The very nature 
of the case precludes the possibility 
of such evidence, for the human race 
can no more be expected to testify to 
its own origin than a child can be 
tendered as a witness of its own birth. 
Our sole inquiry is, what foundation 
circumstantial evidence lends to the 
hypothesis, or whether it lends 
none, or whether it controverts the 
hypothesis. I shall deal with the 
matter entirely as a question of his- 
tory. I shall not indulge in the dis- 
cussion of any speculative probabili- 
ties. I shall not attempt to show that 
Nature is unintelligible unless we 
adopt some such hypothesis. For LECTURES ON EVOLUTION. 
anything 1 know about the matter, it 
may be the way of Nature to be un- 
intelligible ; she is often puzzling, 
and I have no reason to suppose that 
she is bound to fit herself to our 
notions. 
command as completely and fully 
negatives that hypothesis as it did 
the preceding one. And I confess 
that I had too much respect for your 
intelligence to think it necessary to 
add that the negation was equally 
clear and equally valid, whatever 
the source from Avhich that hypothe- 
sis might be derived, or whatever the 
authority by which it might be sup- 
ported. I further stated that, accord- 
ing to the third hypothesis, or that of 
evolution, the existing state of things 
is the last term of a long series of 
states, Avhich, when traced back, 
Avould be found to shoAv no interrup- 
tion and no breach in the continuity 
of natural causation. I propose, in 
the present, and the following lec- 
ture, to test this hypothesis rigorously 
by the evidence at command, and to 
inquire how far that evidence can be 
said to be indifferent to it, how far it 
can be said to be favorable to it, and, 
finally, how far it can be said to be 
demonstrative. 
I shall place before you three kinds 
of evidence entirely based upon Avhat 
is known of the forms of animal life 
Avhich are contained in the series of 
stratified rocks. I shall endeavor to 
show yon that there is one kind of 
evidence Avhjch is neutral, Avhich 
neither helps evolution nor is incon- 
sistent with it. I shall then bring for- 
ward a second kind of evidence Avhich 
indicates a strong probability in favor 
of evolution, but does not pi’ove it ; 
and, lastly, I shall adduce athh'd kind 
of evidence which, being as complete 
as any evidence Ave can hope to obtain 
upon such asubject, and being wholly 
and strikingly in favor of evolution, 
may fairly be called demonstrative 
evidence of its occurrence. 
LECTURE 11. 
From almost the origin of the dis- 
cussions about the existing condition 
of the animal and vegetable worlds 
and the causes Avhich have determined 
that condition, an argument has been 
put forward as an objection to evo- 
lution, which Ave shall have to con- 
sider very seriously. It is an argu- 
ment Avhich was first clearly stated 
by Cuvier in his criticism of the 
doctrines propounded by bis great 
contemporary, Lamarck. The French 
expedition to Egypt had called the 
a'tention of learned men to the Avon- 
derful store of antiquities in that 
country, an 1 there had been brought 
back to France numerous mummified 
corpses of the animals which the an- 
cient Egyptians revered and pre- 
served, and which, at a reasonable 
computation, must have lived not less 
than three or four thousand years be- 
fore the time at which they Avere thus 
brought to light. Cuvier endeavored 
to test the hypothesis that animals 
have undergone gradual and pro- 
gressive modifications of structure, 
by comparing the skeletons and such 
other parts of the mummies as were 
The Hypothesis of Evolution.— The 
Neutral and the Favorable Evi- 
dence. 
In the preceding lecture I pointed 
out that there are three hypotheses 
which may be entertained, and which 
have been entertained, respecting the 
past history of life upon the globe. 
According to the first of these hypo- 
theses, living beings, such as now 
exist, have existed from all eternity 
upon this earth. We tested that 
hypothesis by the circumstantial evi- 
dence, as I called it, which is fur- 
nished by the fossil remains con- 
tained in the earth’s crust, and we 
found that it was obviously unten- 
able. I then proceeded to consider 
the second hypothesis, which I termed 
the Miltonic hypothesis, not because 
it is of any particular consequence to 
me whether John Milton seriously 
entertained it or not, but because it 
is stated in a clear and unmistakable 
manner in his great poem. I pointed 
out to you that the evidence at our LECTURES ON EVOLUTION. 
13 
fat a fitting state of preservation, with 
the corresponding parts of the repre- 
sentatives of the* same species now 
living in Egypt. He arrived at the 
conviction that no appreciable change 
had taken place in these animals in 
the course of this considerable lapse 
of time, and the justice of his con- 
clusion is not disputed. 
there are found remains of animals 
in perfect preservation, and among 
them, shells belonging to exactly the 
same species as those which at present 
inhabit the still waters of Lake Erie. 
It is evident, from the structure of the 
country, that these animal remains 
were deposited in the beds in which 
they occur at a time when the lake ex- 
tended over the region in which they 
are found. This involves the con- 
clusion that they lived and died be- 
fore the falls had cut their way back 
through the gorge of Niagara; and, 
indeed, it has Been determined that, 
when these animals lived, the falls of 
Niagara must have been at least six 
miles further down the river than 
they are at present. Many coraputa- 
sions have been made of the rate at 
which the falls are thus cutting their 
way back. Those computations have 
varied greatly, but 1 believe I am 
speaking within the bounds of pn?' 
dence, if I assume that the falls of 
Niagara have not retreated at a 
greater pace than about a foot a year. 
Six miles, speaking roughly, a;e 30,- 
000 feet; 30,000 feet, at a loot a year, 
gives 30,000 years ; and thus we are 
fairly justified in concluding that no 
less a period than this has passed since 
the shell-fish, whose remains are left 
in the beds to which I have referred, 
were living creatures. 
It is obvious that, if it can be 
proved that animals have endured, 
without undergoing any demonstra- 
ble change of structure, for so long a 
period as four thousand years, no 
form of the hypothesis of evolution 
which assumes that animals undergo 
a constant and necessary progressive 
change can be tenable; unless, in- 
deed, it be further assumed that four 
thousand years is too short a time for 
the production of a change sufficient- 
ly great to be detected. 
but it is no less plain that if the 
process of evolution of animals is not 
independent of surrounding condi- 
tions; if it may be indefinitely hast- 
ened or retarded by variations in 
these conditions; or if evolution is 
simply a process of accomodation to 
varying conditions; the argument 
against the hypothesis of evolution 
based on the unchanged character of 
the Egyptian fauna is worthless. For 
the monuments which are coeval with 
the mummies testify as strongly to 
the absence of change in the physical 
geography and the general condi- 
tions of the land of Egypt, for the 
lime in question, as the mummies do 
to the unvarying characters of its 
living population. 
But there is still stronger evidence 
of the long duration of certain types. 
I have already stated that, as we work 
our way through the great series of 
the Tertiary formations, we lind 
many species of animals identical 
with those which live at the present 
day, diminishing in numbers, it is 
true, but still existing, in a certain 
proportion, in the oldest of the Ter- 
tiary rocks. Furthermore, when we 
examine the rocks of the Cretaceous 
epoch, we find the remains of some 
animals which the closest scrutiny 
cannot show to be, in any important 
respect, different from those which 
live at the present time. That is the 
case with one of the cretaceous lamp- 
shells (Terehratula), which has con- 
tinued to exist unchanged, or with 
The progress of research since 
Cuvier’s time has supplied far more 
striking examples of the long dura- 
tion of the specific forms of life than 
those which are furnished by the 
mummified Ibises and Crocodiles of 
Egypt. A remarkable case is to be 
found in your own country, in the 
neighborhood of the falls of Ni- 
agara. In the immediate vicinity 
oi the whirlpool, and again upon 
Goat Island, in the superficial de- 
posits which cover the surface of 
the rocky subsoil in those regions, ' 14 
LECTURES ON EVOLUTION. 
insignificant variations, down to the 
present day. Such is the case with 
the Globigerince,the skeletons of which 
aggregated together, form a large 
proportion of our English chalk 
Those Globigerince can be traced 
down to the Globigerince which lived 
at the surface of the present great 
oceans, and the remains of which, 
falling to the bottom of the sea, give 
rise to a chalky mud. Hence it must 
be admitted that certain existing 
species of animals show no distinct 
sign of modification, or transforma- 
tion, in the course of a lapse of time 
as great as that which carries us back 
to the Cretaceous period; and winch, 
whatever its absolute measure, is cer- 
tainly vastly greater than thirty 
thousand years. 
in order to distinguish them from 
modern scorpions. 
More than this. At the very bot- 
tom of the Silurian series, in beds 
which are by some authorities referred 
to the Cambrian formation, where 
the signs of life begin to fail us—- 
even there, among the few and scan- 
ty animal remains which are discover- 
able, we find species of molluscous 
animals which are so closely allied to 
existing forms that, at one time, they 
were grouped under the same generic 
name. I refer to the well-known 
Lingula of the Lingula flags, lately, 
in consequence of some slight differ- 
ences, placed in the new genus Lin- 
gulella. Practically, it belongs to the 
same great generic group as the Lin- 
gula, which is to be found at the 
present day upon your own shores and 
those of many other parts of the 
world. 
There are groups of species so 
closely allied together that it needs 
the eye of a naturalist to dis- 
tinguish them one from another. If 
w7e disregard the small differ- 
ences which separate these forms 
and consider all the species of 
such groups as modifications of 
one type, we shall find that, even 
among the higher animals, some types 
have had a marvellous duration. In 
the chalk, for example, there is found 
a fish belonging to the highest and 
most differentiated group of osseous 
fishes, which goes by the name of 
jßeryx. The remains of that fish are 
among the most beautiful and well 
preserved of the fossils found in our 
English chalk. It can be studied an- 
atomically, so far as the hard parts are 
concerned, almost as well as if it were 
a recent fish. But the genus JBeryx 
is represented, at the present day, by 
very closely allied species, which are 
living in the Pacific and Atlantic 
Oceans. We may still go farther 
back. I have already referred to the 
fact that the Carboniferous forma 
tions, in Europe and in America, con- 
tain the remains of scorpions in an 
admirable state of preservation, and 
that those scorpions are hardly dis- 
tinguishable from such as now live. 
I do not mean to say that they are not 
different, but close scrutiny i» needed 
The same truth is exemplified if we 
turn to certain great periods of the 
earth’s history—as, for example, the 
Mesozoic epoch. There are groups 
of reptiles, such as the Ichthyosauria 
and Flesiosauria, .which appear 
shortly after the commencement of 
this epoch, and they occur in vast 
numbers. They disappear with the 
chalk and, throughout the whole of 
the great Mesozoic rocks, they pre- 
sent no such modifications as can 
safely be considered evidence of pro- 
gressive modification. 
Facts of this kind are undoubtedly 
fatal to any form of the doctrine of 
evolution which postulates the sup- 
position that there is an intrinsic ne- 
cessity, on the part of animal forms 
which have once come into existence, 
to undergo continual modification; and 
they are as distinctly opposed to any 
view which involves the belief that such 
modification as may occur, must take 
place, at the same rate, in all the dif- 
ferent types of animal or vegetable 
life. The facts, as I have placed them 
before you, obviously indirectly con- 
tradict any form of the hypothesis of 
evolution which stands in need of 
these two postulates. 
But, one great service that ha* LECTURES ON EVOLUTION. 
been rendered by Mr. Darwin to the 
doctrine of evolution in general is 
this : he has shown that there are two 
chief factors in the process of evolu- 
tion : one of them is the tendency to 
vary, the existence of which in all 
living forms may be proved by ob- 
servation; the other is the influence 
of surrounding conditions upon what 
I may call the parent form and the 
variations which are thus evolved 
from it. The cause of the produc- 
tion of variations is a matter not at 
all properly understood at present. 
Whether variation depends upon 
some intricate machinery—if I may 
use the phrase—of the living organ- 
ism itself, or whether it arises through 
the influence of conditions xipon that 
form, is not certain, and the question 
may, for the present, be left open. 
But the important point is that, 
granting the existence of the tendency 
to the production of variations ; then, 
whether the variations which are pro- 
duced shall survive and supplant the 
parent, or whether the parent form 
shall survive and supplant the vari- 
ations, is a matter which depends en- 
tirely on those conditions which give 
rise to the struggle for existence. If 
the surrounding conditions are such 
that the parent form is more compe- 
tent to deal with them and flourish in 
them than the derived forms, then, 
in the struggle for existence, the 
parent form will maintain itself and 
the derived forms will be extermina- 
ted. But if, on the contrary, the con- 
ditions are such as to be more favor- 
able to a derived than to the parent 
form, the parent form wall be extir- 
pated and the derived form will take 
its place. In the first case, there will 
be no progression, no change of struc- 
ture, through any imaginable series of 
ages ; in the second place, there will 
be modification and change of form. 
obtained, such as existed when th« 
scorpions of that epoch flourished; 
conditions in which scorpions find 
themselves better off, more compe- 
tent to deal with the difficulties in 
their way, than any variation from 
the scorpion type which they may 
have produced, and, for that reason, 
the scorpion type has persisted, and 
has not been supplanted by any other 
form. And there is no reason, in the 
nature of things, why, as long as this 
world exists, if there be conditions 
more favorable to scorpions than to 
any variation which may arise from 
them these forms of life shuld not per- 
sist. 
Therefore, the stock objection to 
the hpothesis of evolution, based on 
the long duration of certain animal 
and vegetable types, is no objection 
at all. The facts of this character— 
and they are numerous—belong to 
that class of evidence which 1 have 
called indifferent. That is to say, 
they may afford no direct support to 
the doctrine of evolution, but they 
are capable of being interpreted in 
perfect consibtency with it. 
There is another order of facts be- 
longing to the class of negative or in- 
different evidence. The great group 
of Lizards, which abound in the pre- 
sent world, extends through the whole 
series of formations as far back as the 
Permian, or latest Palaeozoic, epoch. 
These Permian lizavds differ astonish- 
ingly little from the lizai’ds which 
exist at the present day. Comparing 
the amount of the differences between 
them and modern lizards, with the 
prodigious lapse of time between the 
Permian epoch and the present age, 
it may be said that the amount of 
change is insignificant. But, when 
we carry our researches farther back 
in time, we find no trace of lizards, 
nor of any true reptile whatever, in 
the whole mass of formations beneath 
the Permian. 
Thus the existence of these persist- 
ent types, as I have termed them, is 
no real obstacle in the way of the 
theory of evolution. Take the case of 
scorpions to which I have just refer- 
red. No doubt, since the Carbonifer- 
ous epoch, conditions have always 
Now, it is perfectly clear that if our 
palaeontological collections are to be 
taken, even approximately, as an 
adequate representation of all the 
forms of animals and plants that have LECTURES ON EYOT. JEON. 
ever lived ; and if the record furnished 
by the known series of beds of strati- 
fied rocks, covers the whole series of 
events which constitute the history of 
life on the globe, such a fact as this 
directly contravenes the hypothesis of 
evolution; because this hypothesis 
postulates that the existence of every 
form must have been preceded by that 
of some form little different from it. 
Here, however, we have to take into 
consideration that important truth so 
well insisted upon by Lyell and by Dar 
win—the imperfection of the geologi- 
cal record. It can be demonstrated 
that the geological record must be in 
complete, that it can only preserve 
remains found in certain favorable 
localities and under particular condi 
tions ; that it must be destroyed by 
processes of denudation, and obliter- 
ated by processes of metamorphosis. 
Beds of rock of any thickness, 
crammed full of organic remains, may 
yet, either by the percolation of water 
through them, or by the influence of 
subterranean heat, lose all trace of 
these remains, and present the appear- 
ance of beds of rock formed under 
conditions in which living forms were 
absent. Such metamorphic rocks 
occur in formations of all ages ; and, 
in various cases, there are very good 
grounds for the belief that they have 
contained organic remains, and that 
those remains have been absolutely 
obliterated. 
my ffigmd, Professor Marsh, with 
whom I had the opportunity recently 
of visiting; the precise locality in 
Massachusetts in which these tracks 
Fio. 2.—Tracks of Bkontozodm. 
occur. I am, therefore, able to give 
yuu ray own testimony, if needed, 
that the diagram accurately represents 
what we eaw. The valley of the Con 
necticut is classical ground for the 
geologist. It contains great beds of 
sandstoi.e, covering many square 
miles, which have evidently formed a 
part of an ancient sea-shore, or, it 
may be, lake-shore. For a certain 
period of time after their deposition, 
these beds have remained sufficiently 
soft to receive the impressions of the 
feet of whatever animals walked 
over them, and to preserve them af- 
terwards, iu exactly the same way aa 
such impressions are at this hour pre- 
served on the shores of the Bay of 
Funday and elsewhere. The diagram 
represents the track of some gigantic 
animal, which walked on its hind legs. 
You see the series of marks made al- 
ternately by the right and by the left 
foot; so that, from one impression to 
I insist upon the defects of the geo- i 
logical record the more because those 
who have not attended to these mat- ; 
ters are apt to say, “It is all very 
well, but when you get into a diffi- ] 
culty with your theory of evolution, 1 
you appeal to the incompleteness and ! 
the imperfection of the geological j 
record and I want to make it per- < 
fectly clear to you that this imperfec- 1 
tion is a great fact, which must be x 
taken into account in all our specula- f 
tions, or we shall constantly be going J 
wrong. i 
You see the singular series of foot- i 
marks, drawn of its naturalsize in the 
large diagram hanging up here (Fig. t 
8), which 1 owe to the kindness of f LECTURES ON EVOLUTION. 
17 
the other of the three toed foot on the 
same side, is one stride, and that 
stride, as we measured it, is 
six feet nine inches. I leave you, 
therefore, to form an impression of 
the magnitude of the creature which, 
as it walked along the ancient shore, 
made these impressions. 
the time it was formed. I believe 
that, with a right understanding tf 
the doctrine of evolution on the one 
hand, and a just estimation of the 
importance of the imperfection of the 
geological record on the other, all 
difficulty is removed from the kind of 
evidence to which I have adverted; and 
that we are justified in believing that 
all such cases are examples of what I 
have designated negativeorindifferent 
evidence—that is to say, they in no 
way directly advance the hypothesis 
of evolution, but they are not to be 
regarded as obstacles in the way of 
our belief in that doctrine. 
I now pass on to the consideration of 
those cases which, for reasons which 
I will point out to you by and by, are 
not to be regarded as demonstrative 
of the truth of evolution, but which 
are such as must exist if evolution be 
true, and which therefore are, upon 
the whole, evidence in favor of the 
doctrine. If the doctrine of evolution 
be true, it follows that, however di- 
verse the different groups of animals 
and of plants may be, they must all, 
at one time or other, have been con- 
nected by gradational forms; so that, 
from the highest animals, whatever 
they may be, down to the lowest speck 
of protoplasmic matter in which life: 
can be manifested, a series of grada- 
tions, leading from one end of the se- 
ries to the other, either exists or has. 
existed. Undoubtedly that is a ne- 
cessary postulate of the doctrine of 
evolution. But when we look upon; 
living Nature as it is, we find a to- 
tally different state of things. We 
find that animals and plants fall into 
groups, the different members of 
which are pretty closely allied to- 
gether, but which are separated by 
definite, larger or smaller, breaks from 
other groups. In other words, no in- 
termediate forms which bridge over 
these gaps or intervals are, at present, 
to be met with. 
To illustrate what I mean : Let mo 
call your attention to those vertebrate 
animals which are most familiar to 
you, such as mammals, birds and rep- 
tiles. At the present day, thes^ 
Of such impressions there are un- 
told taousands upon these sandstones. 
Fifty or sixty different kinds have 
been discovered, and they cover vast 
areas. But, up to this present time, 
not a bone, not a fragment, of any 
one of the animals which left these 
great footmarks has been found ; in 
fact, the only animal remains which 
have been met with in all these depos- 
its, from the time of their discovery 
to the present day—though they have 
been carefully hunted over—is a 
fragmentary skeleton of one of the 
smaller forms. What has become of 
the boi ys of these animals'? You see 
we are not dealing with little crea- 
tures, but with animals that make a 
step of six feet nine inches; and their 
remains must have been left some- 
where. The probability is, that they 
have been dissolved away, and abso- 
lutely lost. 
I have had occasion to work out 
the nature of fossil remains, of which 
there was nothing left except casts of 
the bones, the solid material of the 
skeleton having been dissolved out by 
percolating water. It was a chance, 
in this case, that the sandstone hap- 
pened to be of such a constitution as 
to set, and to allow the bones to be 
afterward dissolved out, leaving cavi- 
ties of the exact shape of the bones. 
Had that constitution been other than 
what it was, the bones would have 
been dissolved, the layers of sand- 
stone would have fallen together into 
one mass, and not the slightest indi- 
cation that the animal had existed 
would have been discoverable. 
I know of no more striking evi- 
dence than these facts afford, of the 
caution which should be used in 
drawing the conclusion, from the ab- 
sence of organic remains in a deposit, 
that animals or plants did not exist at LECTURES ON EVOLUTION. 
groups of animals are perfectly well 
defined from one another. We know 
of no animal now living which, in any 
sense, is intermediate between the 
mammal and the bird, or between the 
bird and the reptile ; but, on the con- 
trary, there are many very distinct 
anatomical peculiarities, well defined 
marks, by which the mammal is | 
separated from the bird, and the bird { 
from the reptile. The distinctions i 
arc obvious and striking if you corn- j 
pare the definitions of these great | 
groups as they now exist. 
It is a very remarkable circum- 
stance that, from the commencement 
of the serious study of fossil remains, 
in fact, from the time when Cuvier 
began bis brilliant researches upon 
those found in the quarries of Mont- 
martre, palaeontology has shown what 
she Avas going to do in this matter, 
and what kind of evidence it lay in 
her power to produce. 
I said just now that,in the existing 
Fauna, the group Gf pig-like animals 
and the group of ruminants are en- 
tirely distinci ; but one of the first of 
Cuvier’s discoveries was an animal 
which he called the A voplotherium, 
and which proved to be, in a great 
many important respects, intermediate 
in character between the pigs, on the 
one nand, and the ruminants on the 
other. Thus research into the history 
of the past did, to a certain extent, 
tend to fill up the breach between the 
group of ruminants and the group of 
pigs. Another remarkable animal 
restored by the great French palaeon- 
tologist, the Palveotherium, similarly 
tended to connect together animals to 
all appearance so different as the rhi- 
noceros, the horse, and the tapir. Sub- 
sequent research has brought to light 
multitudes of facts of the same order; 
and, at the present day, the investi- 
gations of such anatomists as Ruti- 
meyer and Gaudry have tended to fill 
up, more and more, the gaps in our 
existing series of mammals, and to 
connect groups formerly thought to 
be distinct. 
The same may be said of many of 
the subordinate groups, or orders, 
into which these great classes are 
divided. At the present time, for 
example, there are numerous forms of 
non-ruminant pachyderms, or what we 
may call broadly, the pig tribe, and 
many varieties of ruminants. These 
latter have their definite characteris- 
tics, and the former have their distin- 
guishing peculiarities. But theie is 
nothing that fills up the gap between j 
the ruminants and the pig tribe. The 
two are distinct. Such also is the 
case in respect of the minor groups of | 
the class of reptiles. The existing j 
fauna shoAvs us crocodiles, lizards, | 
snakes, and tortoises ; but no connec- 
ting link between the crocodile and j 
lizard, nor between the lizard and the I 
snake, nor between the snake and the 
crocodile, nor between any two of 
these groups. They are separated by 
absolute break-'. If, then, it could 
be shown that this state of things had 
always existed, the fact Avouldbe fatal 
to the doctrine of evolution. If the 
intermediate gradations, which the 
doctrine of evolution requires to have 
existed between these groups, are not 
to be found anywhere in the re- 
cords of the past history of the 
globe, their absence is a strong and 
Aveighty negative argument against 
evolution ; Avhile, on the other hand, 
if such intermediate forms are to 
be found, that is so much to the 
good of evolution ; although, for rea- 
sons which I will lay before you by 
and by, we must be cautious in our 
estimate of the evidential cogency of 
facts of this kind. 
But I think it may have an especial 
interest if, instead of dealing with 
these examples, which would require 
a great deal of tedious osteological 
detail, I take the case of birds and 
reptiles; groups which, at the present 
day, are so clearly distinguished from 
one another that there are perhaps no 
classes of animals which, in popular 
apprehension, are more completely 
separated. Existing birds, as you are 
aware, are covered with feathers; their 
anterior extreraeties, specially and pe- 
culiarly modified, are converted into 
wings, by the aid of which most of 
them are able to fly; they walk up- 
right on two legs; and these limbi, LECTURES ON EVOLUTION. 
19 
when they are considered anatomical- 
ly, present a great number of exceed- 
ingly remarkable peculiarities, to 
which I may have occasion to advert 
incidentally as I go on, and which are 
not met with, even approximately, in 
any existing forms of reptiles. On 
the other hand, existing reptiles have 
no feathers. They may have naked 
skins, or be covered with horny scales, 
or bony plates, or with both. They 
possess no wings; they neither fly by 
means of their fore-limbs, nor habitu- 
ally walk upright upon their hind 
limbs; and the bones cf their legs 
present no such modifications as we 
find in birds. It is impossible to im- 
agine any two groups more definitely 
and distinctly separated, notwith- 
standing certain characters which 
they possess in common. 
lessor Marsh in these creta«eou» 
rocks of Western America, have re- 
warded him with the discovery of 
forms of birds of which we had hith- 
erto no conception. By his kindness, 
I am enabled to place betore yon a re- 
storation of one of these extraordinary 
birds, every part of which can be 
thoroughly justified by the more or less 
complete skeletons, in a perfect state 
of preservation, which he has discov- 
ered. This Hesperornis (Fig 3), which 
measured between five and six feet in 
length, is astonishingly like our exist- 
ing divers or grebes in a great many 
respects; so like them, indeed, that, 
had the skeleton of Hesperornis been 
found in a museum without its skull, 
it probably would have been placed 
in the same group of birds as the 
divers and grebes of the present day.* 
But Hesperornis differs from all ex- 
isting birds, and so far resembles 
reptiles, in one important particular 
—it is provided with teeth. The, 
long jaws are armed with teeth which 
have curved crowns and thick roots 
(Fig. 4), and are not set in distinct 
sockets, but are lodged in a groove. 
In possessing true teeth, the Ilesper- 
ornis differs from every existing 
bird, and from every bird yet discov- 
ered in the tertiary formations, the 
tooth-like serrations of the jaws in 
the Odontopteryx of the London 
clay, being mere processes of the 
bony substance of the jaws, and not 
teeth in the proper sense of the word. 
In view of the characteristics of this 
bird we are therefore obliged to mod- 
ify the definitions of the classes of 
birds and reptiles. Before the dis- 
covery of Hesperornis, the definition 
of the class Aves based upon our 
knowledge of existing birds, might 
have been extended to all birds; it 
might have been said that the ab- 
sence of teeth was characteristic of 
As we trace the history of birds 
back in time, we tind their remains, 
sometimes in great abundance, 
throughout the whole extent of the 
tertiary rocks; but, so far as our 
present knowledge goes, the birds of 
the tertiary rocks retain the same es- 
sential characters as the birds of the 
present day. In other words, the 
tertiary birds come within the defini- 
tion of the class constituted by exist- 
ing birds, and are as much separated 
from reptiles as existing birds are. 
Not very long ago no remains of 
birds had been found below the ter- 
tiary rocks, and I am not sure but that 
some persons were prepared to dem- 
onstrate that they could not have ex- 
isted at an earlier period. But, in the 
course of the last few years, such re- 
mains have been discovered in Eng- 
land; though, unfortunately, in so im- 
perfect and fragmentary a condition, 
that it is impossible to say whether 
they differed from existing birds in 
any essential character or not. In 
your country, the development of 
the cretaceous series of rocks is enor- 
mous; the conditions under which the 
latter cretaceous strata have been de- 
posited are highly favorable to the 
preservation of organic remains; and 
the researches, full of labor and r>sk, 
which have been carried on by Pro- 
* The absence of any keel on the 
breast-bone and some other osteological 
peculiarities, observed by Professor 
Marsh, however, suggest that Hesperorni* 
may be a modification of a less special- 
ized group of birds than that to which 
these existing acquatic birds belong. LECTURES ON DEVOLUTION. 
the class of birds ; but the discovery 
of an animal which, in every part of 
its skeleton, closely agrees with exist- 
ing birds, and yet possesses teeth, 
shows that there were ancient birds 
which in respect of possessing teeth, 
approached reptiles more nearly than 
any existing bird does, and, to that 
extent, diminishes the hiatus be- 
tween the two classes. 
The same formation has yielded 
another Bird Ichthyornis (Fig. 6), 
of the vertebrae of existing and of all 
known tertiary birds, but were concave 
at each end. This discovery leads ns 
to make a further modification in the 
definition of the group of birds, and 
to part with another of the characters 
by which almost all existing birds are 
distinguished from teptiles. 
Apart from, tne few fragmentary 
remains from the English greensand, 
to which I have referred, the mesozoic 
rocks, older than those in which Hes- 
Pig. 8.—Hesperornis Regalis (Marsh). 
which also possesses teeth; but the 
teeth are situated in distinct sockets, 
while those of Hesperornis are not so 
lodged. The latter also has such 
very small, almost rudimentary, 
wings, that it must have been chiefly 
a swimmer and a diver, like a Pen- 
guin ; while Ichthyornis has strong 
wings, and no doubt possessed corre- 
sponding powers of flight. Ichthyornis 
also differed in the fact that its verte- 
brae have uot the peculiar characters 
perornis and Ichthyornis have been 
discovered have afforded no certain 
evidence of birds, with the remarkable 
exception of the Solenhofen slates. 
These so-called slates are composed of 
a tine grained calcareous mud, which 
has hardened into lithographic stone, 
and in which organic remains are al- 
most as well preserved as they 
would be if they had been im- 
bedded in so much plaster of 
Paris. They yielded the Archa- LECTURES ON EVOLUTION. 
opteryx, the existence of which was 
first made known by the finding of 
a fossil feather, or rather of the im- 
pression of one. It is wonderful 
enough that such a perishable thing 
as a feather, and nothing more, should 
fortunately wanting, and it is there- 
fore uncertain whether the Archm- 
opteryx possessed teeth or not. But 
the remainder of the skeleton is so 
well preserved as to leave no doubt 
respecting the main features of the 
Fig. 4.—Hesperornis Ebgalis (Marsh). 
(Side and upper views of half the lower jaw; side and end views of a vertebra and* 
separate tooth.) 
be discovered; yet, for a long time, 
nothing was known of this bird ex- 
cept its feather. But, by and by a 
solitary skeleton was discovered,which 
is now in the British Museum. The 
skull of this solitary specimen is un- 
animal, which are very singular. 
The feet are not only altogether bird- 
like, but have the special characters 
of the feet of perching birds, while 
the body had a clothing of true feath- 
ers. Nevertheless, in some other LECTURES ON EVOLUTION. 
respects, Archaeopteryx is unlike a 
bird and like a reptile. There is a 
long tail composed of many verte- 
brae. The structure of the wing dif- 
fers in some very remarkable respects 
to the bones of the fingers which lie 
in the palm of the hand, are fused to- 
gether into one mass; and the whole 
apparatus, except the last joints of 
the thumb, is bound up in a sheath of 
Fig. 5.—Ichthyornis Dispar (Marsh.) 
(Side and upper views of half the lower jaw; and side and end viewg of ft 
vertebra.) 
from that which it presents in a true 
bird. In the latter, the end of the 
wing answers to the thumb and two 
fingers of my hand; but the meta- 
carpal bones, or those which answer 
integument, while the edge of the 
hand carries the principal quill-feath- 
ers. In the Archaeopteryx, the upper- 
arm bone is like that of a bird; 
and the two bones of the forearm are LECTURES ON EVOLUTION. 
more or less like those of a bird, but 
the fingers are not bound together— 
they are free. What their number 
may have been is uncertain; but sev- 
eral, if not all, of them were termi- 
nated by strong curved claws, not like 
such as are sometimes found in birds, 
but such as reptiles possess ; so that, 
in the Archwopteryx, we have an ani- 
mal which, to a certain extent, occu- 
pies a midway place between a bird 
and a reptile. It is a bird so far as 
its foot and sundry other parts of its 
skeleton are concerned; it is essen- 
tially and thoroughly a bird by its 
feathers; but it is much more properly 
a reptile in the fact that the region 
which represents the hand has sepa- 
rate bones, with claws resembling 
those which terminate the fore limb 
of a reptile. Moreover, it had a 
long reptile like tail with a fringe of 
feathers on each side ; while in all 
true birds hitherto known, the tail is 
relatively short, and the vertebrae 
which constitute its skeleton are 
generally peculiarly modified. 
Like the 1 noplotherium and the 
JPalceotherium, therefore, Archaeop- 
teryx tends to fill up the interval 
between groups which, in the exist- 
ing world, are widely separated, 
and to destroy the value of the 
definitions of zoological groups 
based upon our knowledge of exis- 
ting forms. And such cases as 
these constitute evidence in favor of 
evolution, in so far as they prove 
that, in former periods of the world’s 
history, there were animals which 
overstepped the bounds of existing 
groups, and tended to merge them 
into larger assemblages. They show 
that animal organization is more flex- 
ible than our knowledge of recent 
forms might have led us to believe ; 
and that many structural permuta- 
tions and combinations, of which the 
present world gives us no indication, 
may nevertheless have existed. 
But it by no means follows, because 
the JPalceotherium has much in com- 
mon with the Horse, on the one hand, 
and with the Rhinoceros on the other, 
that it is the intermediate form 
through which Rhinoceroses have 
passed to become Horses, or vice ver- 
sa ; on the contrary, any such suppo- 
sition would certainly be erroneous. 
Nor do 1 think it likely that the 
transition from the reptile to the bird 
has been effected by such a form as 
Archaeopteryx. And it is convenient 
to distinguish these intermediate 
forms between two groups, which 
do not represent the actual passage 
from the one group to the other, as 
intercalary types, from those linear 
types which, more or less approxi- 
mately, indicate the nature of the 
steps by which the transition from 
one group to the other was effected. 
I conceive that such linear forms, 
constituting a series of natural gra- 
dations between the reptile and the 
bird, and enabling us to understand 
the manner in which the reptilian 
has been metamorphosed into the bird 
type, are really to be found among a 
group of ancient and extinct terres- 
trial reptiles known as the Ornitho- 
scelida. The remains of these ani- 
mals occur througout the series of 
mesozoic formations, from the Trias 
to the Chalk, and there are indica- 
tions of their existence even in the 
latter Palaeozoic strata. 
Most of these reptiles at present 
known are of great size, some having 
attained a length of forty feet or per- 
haps more. The majority resembled 
lizards and crocodiles in their general 
form, and many of them were, like 
crocodiles, protected by an armor of 
heavy bony plates. But, in others, 
the hind limbs elongate and the fore 
limbs shorten, until their relative 
proportions approach those which 
are observed in the short> winged, 
flightless, ostrich tribe among birds. 
The skull is relatively light, and in 
some cases the jaws, though bearing 
teeth, are beak-like at their extremi- 
ties and appear to have been envel- 
oped in a horny sheath. In the part 
of the vertebral column which lies 
between the haunch bones and is 
called the sacrum, a number of 
vertebne may unite together into one 
whole, and in this respect as in some LECTURES ON EVOLUTION. 
details of its structure, the sacrem of 
these reptdes approaches that of 
birds. 
But it is in the structure of the pel- 
vis and of the hind limb that some of 
these ancient reptiles present the most 
remarkable approximation to birds, 
and clearly indicate the way by which 
the most specialized and characteristic 
features of the bi d may have been 
evolved from the cox-responding parts 
in the reptile. 
In Fig. 6, the pelvis and hind limbs 
of a crocodile, a three-toed bird, and 
the ground. Hence, in the crocodile,' 
the body usually lies squat between 
the legs, while, in the bird, it is raised 
upon the hind legs, as upon pillars. 
In the crocodile, the pelvis is ob- 
viously composed of three bones on 
each side: the ilium (II.), the pubis 
{Pb.), and the ischium (Is.). In the 
adult bird there appears to be but one 
bone on each side. The examination 
of the pelvis of a chick, however, 
shows that each half is made up of 
three bones, which answer to those 
which remain distinct throughout life, 
Fig. 6.—Bikd. 
OknITHOSCEXiIDAN. 
Crocodile. 
(The letters have the same signification in all the figuees. IIIlium; a, anterior 
end; h, posterior end; Is., ischium; Pi., pubis; T, tibia; F, fibula; As 
astragalus; Ca., calcaneum ; 1, distal portion of the tarsus ; i., ii., iff., iy., met- 
atarsal bones.) 
an ornithoscelidan are represented 
side by side ; and, for facility of com- 
parison, in corresponding positions; 
but it must be recollected that, while 
the position of the bird’s limb is na- 
tural, that of the crocodile is not so. 
In the bird, the thigh-bone lies close 
to the body, and the metatarsal bones 
of the foot (ii., iii., iv., Fig. 6) are, 
ordinarily, raised into a more or less 
vertical position ; in the crocodile, the 
thigh-bone stands out at an angle 
from the body, and the metatarsal 
bones (i., ii., iii., iv., Fig. 6) lie flat on 
in the crocodile. There is, therefore, 
a fundamental identity of plan in the 
construction of the pelvis of both bird 
and reptile; though the differences in 
form, relative size, and direction of 
the corresponding bones in the two 
cases are very great. 
But the most stinking contrast be- 
tween the two lies in the bones of the 
leg and of that part of the foot termed 
the tarsus, which follows upon the 
leg. In the crocodile, the fibula {JS) 
is relatively large and its lower endia 
complete. The tibia (T7) has no LECTURES ON EVOLUTION. 
25 
marked crest at its upper end, and its 
lower end is narrow and not pulley- 
shaped. There are two rows of sep- 
arate tarsal bones Ca., &c.) and 
four distinct metatarsal bones, with a 
rudiment of a fifth. 
est. In fact, the ornithoscelidan limb 
is comparable to that of an unhatched 
chick. 
Taking all these facts together, it 
is obvious that the view which was 
entertained by Mantell and the prob- 
ability of which was demonstrated 
by your own distinguished anatomist, 
Leidy, while much additional evi- 
dence in the same direction has been 
furnished by Professor Cope, that 
some of these animals may have 
walked" upon their hind legs, as birds 
do, acquires great weight. In fact, 
there can be no reasonable doubt 
that one of the smaller forms of the 
Ornithoscelida, Compsognathus, the 
almost entire skeleton of which has 
been di covered in the Solenhofen 
slates, was a bipedal animal. The 
parts of this skeleton are somewhat 
twisted out of their natural relations, 
In the bird, the fibula is small and 
its lower end dimiifishes to a point. 
The tibia has a strong crest at its up- 
per end and its lower extremity 
passes into a broad pulley. There seem 
at first to be no tarsal bones; and 
only one bone, divided at the end into 
three heads for the three toes which 
are attached to it, appears in the place 
of the metatarsus. 
In a young bird, however, the pul 
ley shaped apparent end of the tibia 
is a distinct bone, which represents 
the bones marked As., Ca., in the 
crocodile ; while the apparently single 
metatarsal bone consists of three 
bones, which early unite with one an- 
other and with an additional bone, 
which represents the lower row of 
bones in the tarsus of the crocodile. 
In other words, it can be shown by 
the study of developement that the 
bird’s pelvis and hind limb are sim 
ply extreme modifications of the same 
fundamental plan as that upon which 
these parts are modelled in reptiles. 
On comparing the pelvis and hind 
limb of the ornithoscelidan with that 
of the crocodile, on the one side, and 
that of the bird, on the other (Fig 6), 
it is obvious that it represents a mid- 
dle term between the two. The pel- 
vic bones approach the form of those 
of the birds, and the direction of the 
pubis and ischium is nearly that 
which is characteristic of birds; the 
thigh bone, from the direction of its 
head, must have lain close to the 
body; the tibia has a great crest, and, 
immovably fitted on to its lower end, I 
there is a pulley-shaped bone, like that 
of the bird, but remaining distinct. 
The lower end of the fibula is much 
more slender, proportionally, than in 
the crocod le. The metatarsal bones 
have such a form that they fit together 
immovably, though they do not enter 
into bony union; the third toe is, 
as in the bird, longest and strong-' 
Fig. 7.—Restoration or Compsoo- 
NATHUS LONftIPES. 
but the accompanying figure gives a 
1 just view of the general form of 
Gompsognathus and of the proportion 
of its limbs; which, in some respects, 
are more completely bird like than 
those of other Ornithoscelida. 
We have had to stretch the defini- 
tion of the class of birds so as to in- 
clude birds with teeth and birds with 
paw-like fore-limbs and long tails. 
There is no evidence that Gompsogn- 26 
LECTURES ON EVOLUTION. 
othus possessed feathers; but, if it 
did, it would be hard indeed to say 
whether it should be called a reptilian 
bird or an avian reptile. 
As Co nip so gnat hus walked upon his 
hind legs, it must have made tracks 
like those of birds. And as the struc- 
ture of the limbs of sevei'al of the 
gigantic Ornithoscelicla,, such as 
Iguandon, leads to the conclusion that 
they also may have constantly, or oc- 
casionally, assumed the same attitude, 
a peculiar interest attaches to the fact 
that, in the Wealdeu strata of Eng- 
land, there are to be found gigantic 
footsteps, an’anged inoi'der like those 
of the Jirontozoum, and which there 
can be no x-easonable doubt were made 
by some of the Ornithoscelicla, the i’e- 
mains of which are found in the same 
rocks. And, knowing that reptiles 
that walked upon their hind legs and 
shared many of the anatomical chax*- 
acters of birds did once exist, it be- 
comes a very important question 
whether the tracks in the Trias of 
Massachusetts, to which I referred 
some time ago, and which formerly 
used to be unhesitatingly ascribed to 
birds, may not all have been made by 
Ornithoscelidan reptiles; and wheth- 
er, if we could obtain the skeletons 
of the animals which made these 
tracks, we should not find in them 
the actual steps of the evolutional 
process by which reptiles gave rise to 
birds. 
We are not in a position to say that 
the known Ornithoscelida are inter- 
mediate in the order of their appeax*- 
ance on the earth between reptiles 
and birds. All that can be said is 
that, if independent evidence of the 
actual occurrence of evolution is pro- 
ducible, then these intercalary forms 
remove every difficulty in the way of 
understanding what tlie actual steps 
of the process, in the case of birds, 
may have been. 
That intercalary forms snomd have 
existed in ancieut times is a neces- 
sary consequence of the truth of the 
hypothesis of evolution; and, hence, 
the evidence I have laid before you 
in proof of the existence of such 
forms, is, so far as it goes, in favor of 
that hypothesis. 
There is another series of extinct 
reptiles, which may be said to be in- 
tercalary between reptiles and birds, 
in so far as they combine some of the 
characters of both these groups; and, 
which, as they possessed the power 
of flight, may seem, at first sight, to 
be nearer representatives of the forms 
by which the transition from the rep- 
tile to the bird was effected, than the 
Ornithoscelida. 
These are the Pterosauria, or Ptero- 
dactyles, the remains of which are 
met with throughout the series of 
Mesozoic rocks, from the lias to the 
chalk, and some of which attained a 
great size, their wings having a span 
of eighteen or twenty feet. These 
animals, in the form and proportions 
of the head and neck relatively to 
the body, and in the fart that the 
ends of the jaws were often, if not 
always, more or less extensively en- 
sheathed in horny beaks, remind us 
of birds. Moreover, their bones con- 
tained air cavities, rendering them 
specifically lighter, as is the case in 
most birds. The breast bone was 
large and keeled, as in mod birds and 
in bats, and the shoulder girdle is 
strikingly similar to that of ordin »ry 
birds. But, it seems to me, that tha 
special resemblance of pterodactyles 
to birds ends here, unless I may add 
the entire absence of teeth which 
The evidential value of the facts I 
have brought forward in this Lecture 
must be neither over nor under esti- 
mated. It is not historical proof of the 
occurrence of the evolution of birds 
from reptiles, for we have no safe 
ground for assuming that true birds 
had not made their appearance at 
the commencement of the Mesozoic 
epoch. It is, in fact, quite possible 
that all these more or less avi-form 
reptiles of the Mesozoic epoch are not 
terms in the series of progression 
from birds to reptiles at all, but sim- 
ply the more or less modified descend- 
ants of Palaeozoic forms through 
which that transition was actually ef- 
fected. LECTURES ON EVOLUTION. 
characterizes the great pterodactyles 
(.Pteranodon) discovered by Professor 
Marsh. All other known pterodac- 
tyles have teeth lodged in sockets. In 
the vertebral column and the hind 
limbs there are no special resem- 
blances to birds, and when we turn 
to the wings they are found to be 
constructed on a totally different 
principle from those of birds. 
There are four fingers. These four 
fingers are large, and three of them, 
porting a web which extended be- 
ween it and the body. An existing 
specimen proves that such was really 
the case, and that the plerodactylea 
were devoid of feathers, but that the 
fingers supported a vast web like that 
of a bat’s wing; in fact, there can be 
no doubt that this ancient reptile flew 
after the fashion of a bat. 
Thus though the pterodactyle is a 
reptile which has become modified in 
such a manner as to enable it to fly. 
Fig. 8.—Pterodactyltjs Spectabims (Yon Meyer), 
those which answer to the thumb and 
and two following fingers of my 
hand are terminated by claws, 
♦vhile the fourth is enormously pro 
longed and converted into a great 
joint style. You see at once, from 
what I have stated about a bird’s 
wing, that there could be nothing 
less like a bird’s wing than this is. 
It was concluded by general reasoning 
that this finger had the office of sup* 
and therefore, as might be expected, 
presents some points of resemblance 
to other animals which fly; it has, 
so to speak, gone off the line which 
leads directly from reptiles to birds, 
and has become disqualified for the 
changes which lead to the characteris- 
tic organization of the latter class. 
Therefore, viewed in relation to the 
classes of reptiles and birds, the ptero- 
dactyls appear to me to be, in a 28 
LECTURES ON EVOLUTION. 
limited sense, intercalary forms; but 
they ai’e not even approximately 
linear, in the sense of exemplifying 
these modifications of structure 
through which the passage from the 
reptile to the bird took place. 
! denote not merely the domestic ani- 
mals with which we are all so well 
acquainted, but their allies, the ass, 
zebra, quagga, and the like. In short, 
I use “ horses ” as the equivalent of 
the technical name Equidaz, which is 
applied to the whole group of existing 
equine animals. 
LECTURE 111. 
The horse is in many ways a re- 
markable animal; not least so in the 
fact that it presents us with an ex- 
ample of one of the most perfect 
pieces of machinery in the living 
world. In truth, among the works of 
human ingenuity it cannot be said 
that there is any locomotive so per- 
fectly adapted to its purposes, doing 
so much work with so small a quan- 
tity of fuel, as this machine of nature’s 
manufacture—the horse. And, as a 
necessary consequence of any sort of 
perfection, of mechanical perfection 
as of others, you find that the horse is 
a beautiful creature, one of the most 
beautiful of all land-animals. Look 
at the perfect balance of his form, and 
the rhythm and force of its action. 
The locomotive machinery is, as you 
are aware, resident in its slender fore 
and hind limbs; they are flexible and 
elastic levers, capable of being moved 
by very powerful muscles; and, in 
order to supply the engines which 
work these levers with the force which 
they expend, the horse is provided 
with a very perfect apparatus for 
grinding its food and extracting 
therefrom the requisite fuel. 
Without attempting to take you 
very far into the region of osteolog- 
ical detail, I must nevertheless trouble 
you with some statements respecting 
the anatomical structure of the horse; 
and, more especially, will it be need- 
ful to obtain a general conception of 
the structure of its fore and hind 
limbs, and of its teeth. But I shall 
only touch upon those points which 
are absolutely essential to our in- 
quiry. 
Let us turn in the first place to the 
fore-limb. In most quadrupeds, as in 
ourselves, the fore arm contains dis- 
tinct bones called the radius and the 
ulna. The corresponding region in 
The Demonstrative Evidence of Evo- 
lution. 
The occunence of historical facts 
is said to be demonstrated, when the 
evidence that they happened is of 
such a character as to render the as- 
sumption that they did not happen in 
the highest degree improbable ; and 
the question I now have to deal with 
is, whether evidence in favor of the 
evolution of animals of this degree of 
cogency is, or is not, obtainable from 
the record of the succession of living 
forms which is presented to us by 
fossil remains. 
Those who have attended to the 
progress of palaeontology are aware 
that evidence of the character which 
I have defined has been produced in 
considerable and continually-incx-eas- 
ing quantity during the last few years. 
Indeed, the amount and the satisfac- 
tory nature of that evidence are some- 
what surprising, when we consider 
the conditions under which alone we 
can hope to obtain it. 
It is obviously useless to seek for 
such evidence, except in localities in 
which the physical conditions have 
been such as to permit of the deposit 
of an unbroken, or but rarely inter- 
rupted, series of strata through a long 
period of time; in which the group of 
animals to be investigated has existed 
in such abundance as to furnish the 
requisite supply of remains; and in 
which, finally, the materials composing 
the strata are such as to ensure the 
preservation of these remains in a tol- 
erably perfect and undisturbed state. 
It so happens that the case which, 
at present, most nearly fulfils all these 
conditions is that of the series of ex- 
tinct animals which culminates in the 
Horses; by which term I mean to LECTURES ON EVOLUTION. 
29 
the horse seem at first to possess but 
one bone. Careful observation, how- 
ever, enables us to distinguish in this 
bone a part Avhich clearly answers to 
the upper end of the ulna. This is 
closely united Avith the chief mass of 
the bone which represents the radius, 
and runs out into a slender shaft which 
may be traced for some distance 
downwards upon the back of the ra- 
diu , and then in most cases thins out 
and vanishes. It takes still more 
trouble to make sure of what is never- 
theless the fact, that a small part of 
the loAver end of the bone of a horse’s 
fore-arm, which is only distinct in a 
very young foal, is really the lower 
extremity of the ulna. 
slender bone, the fibula. But, in the 
horse, the fibula seems, at first, to be 
reduced to its upper end; a short 
slender bone united with the tibia, 
and ending in a point below, occupy- 
ing its place. Examination of the 
lower end of a young foal’s shin- 
bone, however, shows a distinct por- 
tion of osseous matter which is the 
lower end of the fibula ; so that the, 
apparently single, lower end of the 
shin-bone is really made up of the 
coalesce'! ends of the tibia and fibula, 
just as the, apparently single, lower 
end of the fore arm bone is composed 
of the coalesced radius and ulna. 
The heel of the horse is the part 
commonly known as the hock The 
hinder cannon bone answers to the 
midd'e metatarsal bone of the human 
foot, the pastern, coronary, and coffin 
bones, to the middle toe bones; the 
hind hoof to the nail; as in the fore- 
foot. And, as in the fore-foot, there 
are merely two splints to represent 
the second and the fourth toes. 
Sometimes a rudiment of a fifth toe 
appears to be traceable. 
The teeth of a horse are not less 
peculiar than its limbs. The living 
engine, like all others, must bo well 
stoked if it is to do its work ; and the 
horse, if it is to make good its wear 
and tear, and to exert the enormous 
amount of force required for its pro- 
pulsion, must bo well and rapidly fed. 
To this end, good cutting instruments 
and powerful and lasting crushers are 
needful. Accordingly, the twelve 
cutting teeth of a horse are close-set 
and concentrated in the fore part of 
its mouth, like so many adzes or 
chisels. The grinders or molars are 
large, and have an extremely com- 
plicated structure, being composed of 
a number of different substances of 
unequal hardness. The consequence 
of this is that they wear away at dif- 
ferent rates; and, hence, the surface 
of each grindler is always as uneven 
as that of a good mills'one. 
I have said that the structure of 
the grinding teeth is very complicated, 
the harder and the softer parts being, 
as it were, interlaced with one another. 
What is commonly called the knee 
of a horse is its Avrist. The “cannon 
bone” answers to the middle bone of 
the five metacarpal bones, which sup- 
port the palm of the hand in ourselves. 
The “pastern,” “coronary,” and “cof- 
fin” bones of A’eterinarians answer to 
the joints of our middle fingers, while 
the hoof is simply a greatly enlarged 
and thickened nail. But if what lies 
below the horse’s “knee” thus corre- 
sponds to the middle finger in our- 
selves, what has become of the four 
other fingers or digits? We find in 
the places of the second and fourth 
digits only tAVO slender splint like 
bones, about two-tbirds as long as the 
cannon bone, Avhich gradually taper 
to their loAver ends and bear no finger 
joints, or, as they are termed, pha- 
langes Sometimes, small bony or 
gristly nodules are to be found at the 
bases of these tAvo metacarpal splints, 
and it is probable that these represent 
rudiments of the first and fifth toes. 
Thus, the part of the horse’s skeleton 
which corresponds with that of the 
human hand, contains one overgrown 
middle digit, and at least two imper- 
fect lateral digits; and these answer, 
respectively, to the third, the second, 
and the fourth fingers in man. 
Corresponding modifications are 
found in the hind limb. In ourselves, 
and in most quadrupeds, the leg con- 
tains tAvo distinct bones, a large bone, 
the tibia, and a smaller and more 30 
LECTURES OK EVOLUTION. 
The result of this Is that, as the tooth 
wears, the crown presents a peculiar 
pattern, the nature of which is not 
very easily deciphered at first, but 
which it is important that we should 
understand clearly. Each grinding 
tooth of the upper jaw has an outer 
wall so shaped that, on the worn 
drown, it exhibits the form of two 
crescents, one in front and one behind, 
with their concave sides turned out- 
wards. From the inner sides of the 
front crescent, a crescentic front 
ridge passes inwards and backwards, 
and its inner face enlarges into a 
strong longitudinal fold or “pillar, 
From the front part of the hinder- 
crescent, a hack ridge takes a like 
direction, and also has its pillar. 
The deep interspaces or valleys be- 
tween these ridges and the outer wall 
are filled by bony substance, which is 
called cement, and coats the whole 
tooth. 
pit, which gives rise to the well- 
known “mark” of the (horse. There 
is a large space between the outer in- 
cisors and the front grinder. In this 
space the adult male Viorse presents, 
near the incisors one on each side,above 
and below, a canine or “tush,” which 
is commonly absent in mares. In a 
young horse, moreover, there is not 
unfrequently to be seen, in front of 
the first grinder, a very small tooth, 
which soon falls out. If this small 
tooth be counted as one, it will be 
f )und that there are seven teeth be- 
hind the canine on each side; namely, 
the small tooth in question, and the 
six great grinders, among which, by 
an unusual peculiarity, the foremost 
tooth is rather larger than those which 
follow it. 
I have now enumerated those char- 
acteristic structures of the horse, 
which are of most importance for the 
purpose we have in view. 
To any one who is acquainted with 
the morphology of vertebrated ani- 
mals, they show that the horse devi- 
ates widely from the general structure 
of mammals ; and that the horse type 
is, in many respects, an extreme modi- 
fication of the general mammalian 
plan. The least modified mammals, 
in fact, have the radius and ulna, the 
tibia and fibula, distinct and separate. 
They have five distinct and complete 
digits on each foot, and no one of 
these digits is very much larger than 
the rest. Moreover, in the least modi- 
fied mammals, the total number of the 
teeth is very generally forty-four, 
while in horses, the usual number is 
forty, and in the absence of the ca- 
nines, it may be reduced to thirty- 
six ; the incisor teeth are devoid of the 
fold seen in those of the horse ; the 
grinders regularly diminish in size 
from the middle of the series to its 
front end; while their crowns are 
short, early attain their full length, 
and exhibit simple ridges or tubercles, 
in place of the complex foldings of 
the horse’s grinders. 
The pattern of the worn face of 
each grinding tooth of the lower jaw 
is quite different. It appears to be 
formed of two crescent-shaped ridges, 
the convexities of which are turned 
outwards. The free extremity of 
each crescent has a jpillar, and there 
is a large double pillar where the two 
crescents meet. The whole structure, 
is, as it were, imbedded in cement, 
which fills up the valleys, as in the up- 
per grinders. 
If the grinding faces of an upper 
and of a lower molar of the same side 
are applied together, it will be seen 
that the apposed ridges are nowhere 
parallel, but that they frequently 
cross; and that thus, in the act of 
mastication, a hard surface in the one 
is constantly applied to a soft surface 
in the other, and vice versa. They 
thus constitute a grinding apparatus 
of great efficiency, and one which is 
repaired as fast as it wears, owing to 
the long continued growth of the 
teeth. 
Some other peculiarities of the den- 
tition of the horse must be noticed, as 
they bear upon what I shall have to 
say by and by. Thus the crowns of 
the cutting teeth have a peculiar deep 
Hence the general principles of the 
hypothesis of evolution lead to the 
conclusion that the horse must have LECTURES ON EVOLUTION. 
31 
been derived from some quadruped 
which possessed five complete digits 
on each foot; wdiich had the bones of 
the fore-arm and of the leg complete 
and separate; and which possessed 
forty-four teeth, among which the 
crowns of the incisors and grinders 
had a simple structure; while the lat- 
ter gradually increased in size from 
before backwards, at any rate in the 
anterior part of the series, and had 
short crowns. 
_nd if the horse has been thus 
evolved, and the remains of the differ- 
ent stages of its evolution have been 
preserved, they ought to present us 
with a series of forms in which the 
number of the digits becomes reduced; 
the bones of the fore-arm and leg 
gradually take on the equine con- 
dition ; and the form and arrange- 
ment of the teeth successively approx- 
imate to those which obtain in existing 
horses. 
each, is a digit with three joints of 
the same general character as those 
of the middle digit, only very much 
smaller. These small digits are so 
disposed that they could have had 
but very little functional importance, 
and they must have been rather of 
the nature of the dew-claws, such as 
are to be found in many ruminant 
animals. The Hipparion, as the ex- 
tinct European three-toed horse is 
called, in fact, presents a foot simila" 
to that of the American Frotohippus 
(Fig. 9), except that, in the Hippa- 
rion, the smaller digits are situated 
farther back, and are of smaller pro- 
portional size, than in the Froto- 
hippus. 
The ulna is slightly more distinct 
than in the horse; and the w’hole 
length of it, as a very slender shaft, 
intimately united with the radius, is 
completely traceable. The fibula ap- 
pears to be in the same condition as 
in the horse. The teeth of the Hip- 
parion are essentially similar to those 
of the horse, but the pattern of the 
grinders is in some respects a little 
more complex, and there is a depres- 
sion on the face of the skull in front 
of the orbit, which is not seen in ex- 
isting horses. 
In the earlier Miocene, and perhaps 
the later Eocene deposits of some 
parts of Europe, another extinct 
animal has been discovered, which 
Cuvier, who first described some 
fragments of it, considered to be a 
Faloeotherium. But as further dis- 
coveries threw no light upon its struc- 
ture, it v7as recognized as a distinct 
genus, under the name of Anchi- 
therium. 
Let us turn to the facts, and see 
how far they fulfil these requirements 
of the doctrine of evolution. 
In Europe abundant remains of 
horses are found in the Quaternary 
and later Tertiary strata as far as the 
Pliocene formation. But these horses, 
which are so common in the cave- 
deposits and in the gravels of Eu- 
rope, are in all essential respects like 
existing horses. And that is true of 
all the horses of the latter part of the 
Pliocene epoch. But, in deposits 
which belong to the earlier Pli- 
ocene and later Miocene epochs, and 
which occur in Britain, in France, 
in Germany, in Greece, in India, we 
find animals which are extremely like 
horses—which, in fact, are so similar 
to horses, that you may follow de- 
scriptions given in works upon the 
anatomy of the horse upon the skele- 
tons of these animals—but which 
differ in some important particulars. 
For example, the structure of their 
fore and hind limbs is somewhat 
different. The bones which, in the 
horse, are represented by two splints, 
imperfect below, are as long as the 
metacarpal and metatarsal bones; 
and, attached to the extremity of 
In its general characters, the skele- 
ton of A nc hit her him is very similar 
to that of the horse. In fact, Lartet 
and De Blainville called it 
other ium equinum or hippoides ; and 
De Christol, in 1817, said that it 
differed from Hipparion in little 
more than the characters of its teeth, 
and gave it the name of Hipparithe~ 
rium. Each foot possesses three 
complete toes ; while the lateral toes 
are much larger in proportion to thtt 32 
LECTURES ON EVOLUTION. 
middle toe than in Hipparion, and 
doubtless rested on the ground in or- 
dinary locomotion. 
The ulna is complete and quite dis- 
tinct from the radius, though firmly 
united with the latter. The fibula 
seems also to have been complete. 
Its lower end, though intimately 
united with that of the tibia, is 
clearly marked off from the latter 
bone. 
there was even a shadow of probabll 
ity.* 
And, hence, I have ever since held 
that these facts afford evidence of 
the occurrence of evolution, which, in 
the sense already defined, may be 
termed demonstrative. 
All who have occupied themselves 
with the structure of Anchitherium, 
from Cuvier onwards, have acknow- 
ledged its many points of likeness to 
a well-known genus of extinct Eocene 
mammals, Ealceotherium. Indeed, 
as we have seen, Cuvier regarded his 
remains of Anchitherium as those of 
a species of Ealceotherium. Hence, 
in attempting to trace the pedigree of 
the horse beyond the Miocene epoch 
and the Anchitheroid form, I natur- 
ally sought among the various species 
of Palseotheroid animals for its near- 
est ally,and I was led to conclude that 
the Ealceotherium minus (Elagio~ 
lophus) represented the next sten 
more nearly than any form thou 
known. 
There are forty-four teeth. The 
incisors have no strong pit. The 
canines seem to have been well de- 
veloped in both sexes. The first of 
the seven grinders, which, as I have 
said, is frequently absent, and, when 
it does exist, is small in the horse, is 
a good sized and permanent tooth, 
while the grinder which follows it is 
but little larger than the hinder ones. 
The crowns of the grinders are short, 
and though the fundamental pattern 
of the horse-tooth is discernible, the 
front and back ridges are less curved, 
the accessory pillars are wanting, and 
the valleys, much shallower, are not 
filled up with cement. 
Seven years ago, when I happened 
to be looking critically into the bear- 
ing of palaeontological facts upon the 
doctrine of evolution, it appeared to 
me that the A nchitheriurn, the Hip- 
jparion, and the modern horses, con- 
stitute a series in which the modifica- 
tions of structure coincide with the 
order of chronological occurrence, in 
the manner in which they mu st coin- 
cide, if the modern horses really are 
the result of the gradual metamor- 
phosis, in the course of the Tertiary 
epoch, of a less specialized ancestral 
form. And I found by correspond- 
ence with the late eminent French 
anatomist and palaeontologist, M. 
Lartet, that he had arrived at the 
same conclusion from the same data. ] 
That the Anchitherium type had . 
become metamorphosed into the 
Hipparion type, and the latter into 
the Equine type, in the course of that 1 
period of time which is represented ' 
by the latter half of the Tertiary de- \ 
posits, seemed to me to be the only , 
explanation of the facts for which 
I think that this opinion was fully 
justifiable ; but the progress of inves- 
tigation has thrown an unexpected 
light on the question, and has brought 
us much nearer than could have been 
anticipated to a knowledge of the 
true series of the progenitors of the 
horse. 
You are all aware that when your 
country was first discovered by Euro- 
peans, there were no traces of the 
existence of the horse in any part of 
the American Continent. The ac- 
counts of the conquest of Mexico 
dwell upon the astonishment of the 
natives of that country when they 
first became acquainted with that 
astounding phenomenon a man 
* I use the word “ type ” because it is 
highly probable that many forms of An- 
chitherium- like and Hipparion-like ani- 
mals existed in the Miocene and Pliocene 
epochs, just as many species of the horse 
tribe exist now; and it is highly improb- 
able that the particular species of Anchi- 
thorium or Hipparion, which happen to 
have been discovered, should be precisely 
those which have formed part of the dirsit 
line of the horse’s pedigree. LECTURES ON EVOLUTION. 
33 
seated upon a horse. Nevertheless, 
the investigations of American geol- 
ogists have proved that the remains 
©f horses occur in the most superficial 
deposits of both North and South 
America, just as they do in Europe. 
Therefore, for some reason or other 
no feasible suggestion on that subject 
ro far as I know has been made—the 
horse must have died out in this con- 
tinent at some period preceding the 
discovery of America. Of late years 
there has been discovered in your 
Western Territories that marvellous 
accumulation of deposits, admirably 
adapted for the preservation of or- 
ganic remains, to which I referred 
the other evening, and which fur- 
nishes us -with a consecutive series of 
records of the fauna of the older half 
of the Tertiary epoch, for which we 
have no parallel in Europe. They 
have yielded fossils in an excellent 
state of conservation and in unex- 
ampled number and variety. The 
researches of Leidy and others have 
shown that forms allied to the Hip- 
parlon and the Anchitheriurn are to 
be found among these remains. But 
it is only recently that the admirably 
conceived and most thoroughly and 
patiently worked-out invest gations 
of Professor Marsh have given us a 
just idea of the vast fossil wealth, and 
of the scientific importance of these 
deposits. I have had the advantage 
of glancing over the collections in 
Yale Museum, and I can truly say 
that, so far as my knowledge extends, 
there is no collection from any one 
region and series of strata comparable 
for extent, or for the care with which 
the remains have been got together, 
or for their scientific importance, to 
the series of fossils which he has de- 
posited there. This vast collection 
has yielded evidence bearing upon 
the question of the pedigree of the 
horse of the most striking character. 
It tends to show that we must look 
to America, rather than to Europe, 
for the original seat of the equine 
series; and that the archaic forms 
and successive modifications of the 
horse’s ancestry are far better pre- 
ferred here than in Europe. 
I Professor Marsh’s kindness has 
I enabled me to put before you a dia- 
I gram, every figure in which is an 
j actual representation of some speci- 
| men which is to be seen at Yale at 
this present time (Fig. 9).- 
The succession of forms which he 
has brought together carries ns from 
the top to the bottom of the Tertia- 
ries. Firstly, there is the true horse. 
Next we have the American Pliocene 
form of the horse (.Pliohppus) ; in 
the conformation of its limbs it pre- 
vents some very slight deviations, 
from the ordinary horse, and the 
crowns of the grinding teeth are. 
shorter. Then comes the Proto h 
which represents the European Hip- 
parion, having one large digit and 
two small ones on each foot, and the 
general characters of the fore-arm 
and leg to which I have referred. 
But it is more valuable than the Euro- 
pean Uipparion for the reason that it 
is devoid of some of the peculiarities 
of that form—peculiarities which tend 
to show that the European Hippo- 
rion is rather a member of a col- 
lateral branch than a form in the 
diiect line of succession. Next, in 
the backward order in time, is the 
Miohippus, which corresponds pretty 
nearly with the Anehitherium of 
Europe. It presents three complete 
toes—one large median and two 
smaller lateral ones ; and there is a 
rudiment of that digit, which answers 
to the little finger of the human hand. 
The European record of the pedi- 
gree of the horse stops here; in the 
American Tertiaries, on the contrary, 
the series of ancestral equine forms is 
continued into the Eocene formations. 
An older Miocene form, termed Me~ 
sa/iippus, has three toes in front, with 
a large splint-like rudiment repre- 
senting the little finger; and three 
toes behind. The radius and ulna, 
the tibia and the fibula, are distinct, 
and the short-crowned molar teeth 
are anchitheroid in pattern. 
But the most important discovery 
of all is the Orohipjncs, which comes 
from the Eocene formation, and is the 
oldest member of the equine series, as 
yet known. Here we find four oom- 34 
LECTURES ON EVOLUTION. 
plete toes on the front-limb, three toes 
on the hind-limb, a well-developed 
ulna,a well-developed fibula, and short- 
crowned grinders of simple pattern. 
have been predicted from a knowl- 
edge of the principles of evolution. 
And the knowledge we now possess 
justifies us completely in the antici- 
Fore Foot. Hind Foot. Fore-arm. Leg. Upper Molar. Lower Mai nr. 
RECENT. 
EQTJUS, 
PLIOCENE. 
Pliohippus. 
PROTOHIPPUB 
(Hipparion). 
MIOCENE. 
MIOHIPPTJB 
(Anchitherium'j, 
MBBOHIPPUS, 
EOCENE. 
OBOHIPPtrS. 
Fig 9. 
Thus, thanks to these important 
researches, it has become evident that, 
so far as our present knowledge ex- 
tends, the history of the horse-type is 
exactly and precisely that which could 
pation, that when the still lower 
Eocene deposits, and those which be- 
long to the Cretaceous epoch, have 
yielded up their remains of ancestral 
equine animals, we shall find, first, a LECTURES ON EVOLUTION. 
35 
form with four complete toes and a 
rudiment of the innermost or first 
digit in front, with, probably, a rudi- 
ment of the fifth digit in the hind 
foot;* while, in still older forms, the 
series of the digits will be more and 
mo'-e complete, until we come to the 
five toed animals, in which, if the 
doctrine of evolution is well founded, 
the whole series must have taken its 
origin. 
lacra, are no indications of the former 
existence of the animals to which they 
seem to belong ; but that they are 
either sports of Nature, or special 
creations, intended—as I heard sug- 
gested the other day—to test oui*, 
faith. 
In fact,the whole evidence is in favor 
of evolution, and there is none against 
it. And I say this, although per- 
fectly well aware of the seeming diffi- 
culties which have been built up upon 
what appears to the uninformed to be 
a solid foundation. 1 meet constantly 
with the argument that the doctrine 
of evolution cannot be well founded, 
because it requires the lapse of a very 
vast period of time ; while the dura- 
tion of life upon the earth, thus im- 
plied, is inconsistent with the conclu- 
sions arrived at by the astronomer and 
the physicist. I may venture to say 
that I am familiar with those conclu- 
sions, inasmuch as some years ago, 
when President of the Geological So- 
ciety of London, I took the liberty of 
criticising them, and of showing in 
what respects, as it appeared to me, 
they lacked complete and thorough 
demonstration. But, putting that 
point aside, suppose that, as the 
astronomers, or some of them, and 
some physical philosophers, tell us it 
is impossible that life could have en- 
dured upon the earth for as long a 
period as is required by the doctrine 
of evolution—supposing that to be 
proved—l desire to be informed what 
is the foundation for the statement 
that evolution does require so great a 
time? The biologist knows nothing 
whatever of the amount of time which 
may be required for the process of 
evolution. It is a matter of fact that 
the equine forms, which I have de- 
scribed to you, occur in the order 
stated in the Tertiary formations. But 
I have not the slightest means of 
guessing whether it took a million of 
years, or ten millions, or a hundred 
millions, or a thousand millions of 
years, to give rise to that series of 
changes. A biologist has no mean« 3 
of arriving at any conclusion as 
to the amount of time which 
may be needed for a certaim 
That is what I mean by demon- 
strative evidence of evolution. An 
inductive hypothesis is said to be de- 
monstrated when the facts are shown 
to be in entire accordance with it. If 
that is not scientific proof, there are 
no merely inductive conclusions which 
can be said to be proved. And the doc- 
trine of evolution, at the present time, 
rests upon exactly as secure a foun- 
dation as the Coperniean theory of 
the motions of the heavenly bodies 
did at the time of its promulgation. 
Its logical basis is precisely of the 
same character—the coincidence of 
the observed facts with theoretical 
requirements. 
.The only way of escape, if it be a 
way of escape, from the conclusions 
which I have just indicated, is the 
supposition that all these different 
equine forms have been created sepa- 
rately at separate epochs of time ; and, 
I repeat, that of such an hypothesis as 
this there neither is, nor can be, any 
scientific evidence ; and, assuredly, so 
far as I know, there is none which is 
supported, or pretends to be supported, 
by evidence or authority of any other 
kind. I can but think that the time 
will come when such suggestions as 
these, such obvious attempts to escape 
the force of demonstration, will be 
put upon the same footing as the sup 
position made by some writers, who 
are, I believe, not completely extinct 
at present, that fossils are mere simu- 
* Since this lecture was delivered, Pro- 
fessor Marsh has discovered a new genus 
of equine mammals (Eohippus) from the 
lowest Eocene deposits ol the West, 
which corresponds very nearly to this 
description.—American Journal oj Sci- 
ence, November, 1876. LECTURES ON EVOLUTION. 
quantity of organic change. He takes 
his time from the geologist. The 
geologist, considering the rate at 
which deposits are formed and the 
rate at which denudation goes on 
upon the surface of the earth, arrives 
at more or less justifiable conclusions 
as to the time which is required for 
the deposit of a certain thickness of 
rocks; and if he tells me that the 
Tertiary formations required 500,- 
000,000 years for their deposit, I sup- 
pose he has good ground for what he 
says, and I take that as a mens r; of 
the duration of the evolution of the 
horse from the Orohippus up to its 
present condition. And, if he is 
right, undoubtedly evolution is a 
very slow process, and requires a 
great deal of time. But suppose, 
now, that an astronomer or a physi- 
cist—for instance, my friend Sir Wil- 
liam Thomson—tells me that my geo- 
logical authority is quite wrong ; and 
that he has weighty evidence to show 
that life could not possibly have ex- 
isted upon the surface of the earth 
500,000,000 years ago, because the 
earth would have then been too hot 
to allow of life, my reply is: “ That 
is not my affair; settle that with the 
geologist, and when you have come 
to an agreement among yourselves I 
will adopt your conclusion.” We 
take our time from the geologists 
and physicists : and it is monstrous 
that, having taken our time from the 
physical philosopher’s clock, the phys- 
ical philosopher should turn round 
upon us, and say we are too fast or 
too slow. What we desire to know 
is, is it a fact that evolution took 
place? As to the amount of time 
which evolution may have occupied, 
we are in the hands of the physicists 
and astronomers, whose business it is 
to deal with those questions. 
I have now, ladies and gentlemen, 
arrived at the conclusion of the task 
which I set before myself when I 
undertook to deliver these lectures. 
!My purpose has been, not to enable 
those among you who have paid no 
attention to these subjects before, to 
laave this room in a condition to de- 
cide upon the validity or the in 
validity of the hypothesis of evolu. 
tion; but I have desired to put be- 
fore you the principles upon which 
all hypotheses respecting the history 
of Nature must be judged ; and fur- 
thermore, to make apparent the na- 
ture of the evidence and the amount 
of cogency which is to be expected 
and maybe obtained from it. To this 
end, I have not hesitated to regard 
you as genuine students and persons 
desirous of knowing the truth. I 
have not shrunk from taking you 
through long discussions, that I fear 
may have sometimes tried your pa- 
tience ; and I have inflicted upon you 
details which were indispensible, but 
which may well have been weari- 
some. But I shall rejoice—l shall 
consider that I have done you the 
greatest service which it wTas in my 
power to do—if I have thus con- 
vinced you that the great question 
which we have been discussing is not 
one to be dealt with by rhetorical 
flourishes, or by loose and superficial 
talk; but that it requires the keen 
attention of the trained intellect and 
the patience of the accurate observer. 
When I commenced this series ol 
lectures, I did not think it necessary 
to preface them with a prologue, such 
as might be expected from a stranger 
and a foreigner; for during my brief 
stay in your country, I have found it 
very hard to believe that a stranger 
could be possessed of so many friends, 
and almost harder that a foreigner 
could express himself in your language 
in such a way as to be, to ail appear- 
ances, so readily intelligible. So far 
as I can judge, that most intelligent, 
and, perhaps, I may add, most singu- 
larly active and enterprising body, 
your press reporters, do not seem to 
have been deterred by my accent 
from giving the fullest account of 
everything that I happen to have 
said. 
But the vessel in which I tako my 
departure is even now ready to slip her 
moorings; I awake from my delusion 
that I am other than a stranger and a 
foreigner. lam ready to go back to ON THE STUDY OP BIOLOGY. 
my place and country; but, before do- 
ing so, let me, by way of epilogue, 
tender to you my most hearty thanks 
for the kind and cordial reception 
which you have accorded to me; and 
let me thank you still more for that 
which is the greatest compliment 
which can be afforded to any person 
in my position—the continuous and 
undisturbed attention which you have 
bestowed upon the long argument 
which I have had the honor to lay bv' 
fore you. 
ON THE STUDY OF BIOLOGY 
A Lecture delivered on the occasion of an Exposition of Scientific Appar*• 
tus, in the South Kensington Museum, London, in 1876. 
It is my duty to-night to speak 
about the study of Biology, and 
while it may be that there are many 
of my audience who are quite famil- 
iar with that study; yet as a lecturer 
of some standing, it would, I know 
by experience, be very bad policy on 
my part to suppose such to be exten- 
sively the case. On the contrary, I 
must imagine that there are many of 
you wrho would like to know what 
Biology is; that there are others who 
have that amount of information, 
but would nevertheless gladly hear 
why it should be wrorth their while to 
study Biology; and yet others, 
again, to whom these two points are 
clear, but who desire to learn how 
they had best study it, and, finally, 
when they had best study it. 
I shall, therefore, address myself 
to the endeavor to give you some an- 
swer to these four questions—what 
Biology is ; why it should be studied; 
how it should be studied ; and when 
it should be studied. 
In the first place, in respect to 
what Biology is, there are, I believe, 
some persons who imagine that the 
term “Biology” is simply a new- 
fangled denomination, a neologism in 
•hort, for what used to be known 
under the title of “ Natural History ;w 
but I shall try to show you, on the 
contrary, that the word is the expres- 
sion of the growth of science during 
the last 200 years, and came into ex- 
istence half a century ago. 
At the revival of learning, knowl- 
edge was divided into two kinds— 
the knowledge of nature and the 
knowledge of man; for it was the 
current idea then (and a great deal of 
that ancient conception still remains) 
that there was a sort of essential 
antithesis, not to say antagonism, 
between nature and man; and that 
the two had not very much to do 
with one another, except that the one 
was oftimes exceedingly troublesome 
to the other. Though it is one of the 
salient merits of our great philoso- 
phers of the seventeenth century, 
that they recognized but one scien- 
tific method, applicable alike to mam 
and to nature, we find this notion of 
the existence of a broad distinction 
between nature and man in the 
writings botf of Bacon and of Hobbes 
of Malmesbury; and I have brought 
with me that famous work which 
is now so little known, greatly as it 
deserves to be studied, “The Levia- 
than,” in order that I may put to ON THE STUDY OF BIOLOGY. 
yon in the wonderfully terse and clear 
language of Thomas Hobbes, what 
was his view of the matter. He 
says : 
was not included under astronomy 
came to be spoken of as “natural phil- 
osophy”—a term which Bacon had 
employed in a much wider sense. 
Time went on, and yet other branches 
of science developed themselves. 
Chemistry took a definite shape; and 
since all these sciences, such as as- 
tronomy, natural philosophy, and 
chemistry, were susceptible either of 
mathematical treatment or of experi- 
mental treatment, or of both, a broad 
distinction was drawn between the 
experimental branches of what had 
previously been called natural his- 
tory and the observational branches—■ 
those in which experiment was (or 
appeared to be) of doubtful use, and 
where, at that time, mathematical 
methods were inapplicable. Under 
these circumstances the old name of 
“ Natural History” stuck by the re- 
siduum, by those phenomena, which 
were not, at that time, susceptible 
of mathematical or experimental 
treatment; that is to say, those 
phenomena of nature which come 
now under the general heads of 
physical geograph) , geology, miner- 
alogy, the history of plants, and the 
history of animals. It was in this sense 
that the term was understood by the 
great writers of the middle of the 
last century—Buffon and Linnaeus— 
by Buffon in his great work, the “ His- 
toire Naturelle Generale,” and by 
Linnaeus in his splendid achievement, 
the “Systema Naturae.” The subjects 
they deal with are spoken of as “Nat- 
ural History,” and they called them- 
selves and were called “Naturalists.” 
But you will observe that this was 
not the original meaning of these 
terms; but that they had, by this time, 
acquired a signification widely differ- 
ent from that which they possessed 
primitively. 
The sense in which “ Natural His- 
tory” was used at the time I am now 
speaking of has, to a certain extent, 
endured to the present day. There 
are now in existence in some of our 
northern universities, chairs of “ Civil 
and Natural History,” in which “Nat- 
ural History” is used to indicate ex- 
“The register of knowledge of fact 
is called history. Whereof there be 
two sorts, one called natural history ; 
which is the history of such facts or 
effects of nature as have no depend- 
ence on man’s will; such as are the 
histories of metals, plants, animals, 
regions, and the like. The other is 
civil history; which is the history of 
the voluntary actions of men in com- 
monwealths.” 
So that all history of fact was divid- 
ed into these two great groups of nat- 
ural and of civil history. The Royal 
Society was in course of foundation 
about the time that Hobbes was writ- 
ing this book, which was published 
in 1651; and that Society was termed 
a ‘‘Society for the Improvment of 
Natural Knowledge,” which was then 
nearly the same thing as a “Society 
for the Improvement of Natural His- 
tory.” As time went on, and the va- 
rious branches of human knowledge 
became more distinctly developed and 
separated from one another, it was 
found that some- were much more sus- 
ceptible of precise mathematical 
treatment than others. The publica- 
tion of the “Principia” of Newton, 
which probably gave a greater stimu- 
lus to physical science than any work 
ever published before, or which is 
likely to be published hereafter, 
showed that precise mathematical 
methods were applicable to those 
branches of science such as astronomy, 
and what we now call physics, which 
occupy a very large portion of the do- 
main of what the older writers under- 
stood by natural history. And inas- 
much as the partly deductive and 
partly experimental methods of treat- 
ment to which Newton and others 
subjected these branches of human 
knowledge, showed that the phenom- 
ena of nature which belonged to them 
were susceptible of explanation, and 
thereby came within the reach of what 
was called “philosophy” in those days; 
A 0 much of this kind of knowledge as ON THE STUDY OF BIOLOGY. 
actly what Hobbes and Bacon meant 
by that term. The uhappy incumbent 
of the chair of Natural History is, or 
was, supposed to cover the whole 
ground of geology, mineralogy, and 
zoology, perhaps even botany, in his 
lectures. 
man, Treviranus. Bichat* assumed 
the existence of a special group of 
“physiological” sciences. Lamarck, 
in a work published in 1801, f for the 
first time made use of the name 
“ Biologic,” from the two Greek 
words which signify a discourse 
upon life and living things. About 
the same time it occurred to Trevi- 
ranus, that all those sciences which 
deal with living matter are essen- 
tially and fundamentally one, and 
ought to be treated as a whole ; and, 
in the year 1802, he published the 
first volume of what he also called 
“ Biologic.” Treviranus’s great merit 
lies in this, that he worked out his idea 
and wrote the very remarkable book 
to which I refer. It consists of six 
volumes, and occupied its author for 
twenty years—from 1802 to 1822. 
That is the origin of the term 
“ Biology; ” and that is how it has 
come about that all clear thinkers 
and lovers of consistent nomencla- 
ture have substituted for the old con- 
fusing name of “Natural History,” 
which has conveyed so many mean- 
ings, the term “ Biology,” which de- 
notes the whole of the sciences which 
deal with living things, whether they 
be animals or whether they be plants. 
Some little time ago—in the course 
of this year, I think—l was favored 
by a learned classic, Dr. Field of 
Norwich, with a disquisition, in which 
he endeavored to prove that, from a 
philological point of view, neither 
Treviranus nor Lamarck had 
right to coin this new word “ Biol- 
ogy ” for their purpose ; that, in fact* 
the Greek word “ Bios ” had relation 
only to human life and human a (fairs, 
and that a different word was em- 
ployed by the Greeks when they 
wished to speak of the life of ani- 
mals and plants. So Dr. Field tells 
us we are all wrong in using the term 
biology, and that we ought to employ 
another •, only he is not quite sure 
But as science made the marvellous 
progress which it did make at 
the latter end of the last and 
the beginning of the present cen- 
tury, thinking men began to dis- 
cern that under this title of 
“Natural History” there were in- 
cluded very heterogeneous constitu- 
ents—that, for example, geology and 
mineralogy were, in many respects, 
widely different from botany and 
zoology ; that a man might obtain an 
extensive knowledge of the structure 
and funtions of plants and animals, 
without having need to enter upon the 
study of geology or mineralogy, and 
vice versa; and, further, as knowl- 
edge advanced, it became clear that 
there was a great analogy, a very close 
alliance, between those two sciences 
of botany and zoology which 
deal with living beings, while they 
are much more widely separated 
from all other studies. It is due to 
Buff on to remark that he clearly recog- 
nized this great fact. He says : “ Ces 
deux genres d’etres organises [ies 
animaux et les vegetaux] out beau- 
coup plus de proprietes communes 
que de differences rdeles.” There- 
fore, it is not wonderful, that at the 
beginning of the present century, in 
two different countries, and so far as 
I know, without any intercommuni- 
cation, two famous men clearly con- 
ceived the notion of uniting the 
sciences which deal with living mat- 
ter into one whole, and of dealing 
with them as one dicipline. In fact, 
I may say there were three men to 
whom this idea occurred contempo- 
raneously, although there were but 
two who carried it into effect, and 
only one who worked it out complete- 
ly. The persons to whom I refer 
were the eminent physiologist Bichat, i 
and the great naturalist L rniarck, in j 
France; and a distinguished Ger-1 
* See the distinction between the 
“ sciences physiques ” and the “ sciences 
I physiologiques ” in the “ Anatomic Gen- 
-1 erale,” 1881. 
1 f “ Hydrogeologie,” an, x (1801). ON THE STUDY OF BIOLOGY, 
about the propriety of that which he 
proposes as a substitute. It is a some- 
what hard one—“zootocology.” I am 
sony we are wrong, because we are 
likely to continue so. In these matters 
we must have some sort of “ Statute 
of Limitations.” When a name has 
been employed for half a-century, 
persons of authority * have been 
using it, and its sense has become 
well understood, I am afraid that 
people will go on using it, whatever 
the weight of philological objection. 
why we should not include therein 
human affairs, which in so many cases 
resemble those of the bees in zealous 
get cing, and are not without a certain 
parity in the proceedings of the wolves. 
The real'fact is that we biologists are 
a self-sacrificing people; and inas 
much as, on a moderate estimate, 
there are about a quarter of a million 
different species of animals and plants 
to know about already, we feel that 
we have more than sufficient territory. 
There has been a sort of practical 
convention by which we give up to 
a different branch of science what 
Bacon and Hobbs would have called 
“Civil History.” That branch of sci- 
ence has constituted itself under the 
head of Sociology. I may use phrase- 
ology which, at present, will be well 
understood? and say that we have al- 
lowed that province of Biology to be- 
come autonomous; but I should like 
you to recollect that that is a sacri- 
fice, and that you should not be sur- 
prized if it occasionally happens that 
you see a biologist apparently tres- 
passing in the region of philosophy 
or politics ; or meddling with human 
education; because, after all, that is 
a part of his kingdom which he has 
only voluntarily forsaken. 
■ Now that we have arrived at the 
origin of this word “Biology,” the next 
point to consider is : What ground 
does it cover? I have said that, in 
its strict technical sense, it denotes all 
the phenomena which are exhibited 
by living things, as distinguished 
from those which are not living ; but 
while that is all very well, so long as 
we coniine ourselves to the lower ani- 
mals and to plants, it lands us in con- 
siderable difficulties when we reach 
the higher forms of living things. For 
whatever view we may entertain about 
the nature of man, one thing is per- 
fectly certain, that he is a living crea- 
ture. Hence, if our definition is to be 
interpreted strictly, we must include 
man and all his ways and works under 
the head of Biology; in which case, 
we should find that psychology, poli- 
tics, and political economy would be 
absorbed into the province of Biology. 
In fact, civil history would be merged 
in natural history. In strict logic it 
may be hard to object to this course, 
because no one can doubt that the 
rudiments and outlines of our own 
mental phenomena are traceable 
among the lower animals. They have 
their economy and their polity, and 
if, as is always admitted, the polity of 
bees and the commonwealth of wolves 
fall within the purview of the biolo- 
gist proper, it becomes hard to say 
Having now defined the meaning of 
the word Biology, and having indi- 
cated the general scope of Biological 
Science, I turn to ray second question, 
which is—Why should we' study Bi- 
ology ? Possibly the time may come 
when that will seem a very odd ques- 
tion. That we, living creatures, should 
not feel a certain amount of interest 
in what it is that constitutes our life 
will eventually, under altered ideas of 
the fittest objects of human inquiry, 
appear to be a singular phenomenon; 
but at present, judging by the practice 
of teachers and educators, Biology 
would seem to be a topic that does 
not concern us at all. I propose to 
put before you a few considerations 
with which I dare say many will be 
familiar already, but which will suffice 
to show—not fully, because to dem- 
onstrate this point fully would take a 
great many lectures—that there are 
* “ The term Biology, -which means ex- 
actly what we wish to express, the Science 
of Life, has often been used, and has of 
late become not uncommon among good 
writers.”—Whewell, “Philosophy ot the 
Inductive Sciences,” vol. i. p. 544 (edi- 
tion of 1847). ON THE STUDY OF BIOLOGY., 
most of ns hold by the tradition, that 
man occupies an isolated and peculiar 
position in nature ; that though he is 
in the world, he is not of the world; 
that his relations to things about him 
are of a remote character; that his 
origin is recent, his duration likely to 
be short, and that ho is the great cen- 
tral figure round which other things 
in this world revolve. But this is not 
what the biologist tells us. 
some very good and substantial rea- 
sons why it may be advisable that we 
should know something-about this 
branch of human learning. 
I myself entirely agree with an- 
other sentiment of the philosopher of 
Malmesbury, “that the scope of all 
speculation is the performance of 
some action or thing to be done,” and 
I have not any very great respect for, 
or interest in, mere knowing as such. 
I judge of the value of human pur- 
suits by their bearing upon human in- 
terests; in other words, by their utili- 
ty; but I should like that we should 
quite clearly understand what it is 
that we mean by this word “utility.” 
In an Englishman’s mouth it generally 
means that by which we get pudding 
or praise, or both. I have no doubt 
that is one meaning of the word utili- 
ity, but it by no means includes all I 
mean by utility. I think that knowl- 
edge of every kind is useful in pro- 
portion as it tends to give people right 
ideas, which are essential to the foun- 
dation of right practice, and to re- 
move wrong ideas, which are the no 
less essential foundations and fertile 
mothers of every description of error 
in practice. And inasmuch as, what- 
ever practical people may say, this 
world is, after all, absolutely governed 
by ideas, and very often by the wild- 
est and most hypothetical ideas, it is 
a matter of the very greatest impor- 
tance that our theories of things, and 
even of things that seem a long way 
apart from our daily lives, should be 
as far as possible true, and as far as 
possible removed from error. It is 
not only in the coarser practical sense 
of the word “utility,” but in this higher 
and broader sense, that I measure the 
value of the study of biology by its 
utility; and I shall try to point out to 
you that you will feel the need of 
some knowledge of biology at a great 
many turns of this present nineteenth 
century liftj of ours. For example, 
most of us attach great importance to 
the conception which we entertain of 
the position of man in this universe, 
and his relation to the rest of nature. 
We have almost all been told, and 
0 
At the present moment you will be 
kind enough to separate me from them, 
because it is in no way essential to my 
present argument that I should advo- 
cate their views. Don’t suppose that 
I am saying this for the purpose of 
escaping the responsibility of their be- 
liefs ; indeed, at other times, and in 
other places, I do not think that point 
lias been left doubtful; but I want 
clearly to point out to you that for my 
present argument they may all be 
wrong; and, nevertheless, my argu- 
ment will hold good. The biologists 
tell us that all this is an entire mis- 
take. They turn to the physical 
organization of man. They examine 
his whole structure, his bony frame 
and all that clothes it. They resolve 
him into the finest particles into which 
the microscope will enable them to 
break it up. They c jnsider the per- 
formance of his various functions and 
activities, and they look at the manner 
in which he occurs on the surface of 
the world. Then they turn to other 
animals, and taking the first handy 
domestic animal—say a dog—they 
profess to be able to demonstrate that 
the analysis of the dog leads them, in 
gross, to precisely the same results as 
the analysis of ihe man; that they find 
almost identically the same bones, 
having the same relations ; that they 
can name the muscles of the dog by 
the names of the muscles of the man, 
and the nerves of the dog by those 
of the nerves of the man, and that 
such structures and organs of the 
sense as we find in the man such 
also we find in the dog ; they analyze 
the brain and spinal cord, and they 
find that the mornenclature which fits 
the one answers for the other. They ON THE STUDY OF BIOLOGY. 
carry their microscopic inquiries in 
the case of the dog as far as they 
can, and they find that his body is 
resolvable into the same elements as 
those of the man. Moreover, they 
trace back the dog’s and the man’s 
development, and they find that, 
at a certain stage of their exist- 
ence, the two creatures are not dis- 
tinguishable the one from the other ; 
they find that the dog and his 
kind have a certain distribution 
over the surface of the world, com- 
parable in its way to the distribution 
of the human species. What is true 
of the dog they tell us is true of all 
the higher animals ; and they assert 
that they can lay down a common 
plan for the whole of these creatures, 
and regard the man and the dog, tire 
horse and the ox as minor modifica- 
tions of one great fundamental unity. 
Moreover, the investigations of the 
last three-quarters of a century have 
proved, they tell us, that similar in- 
quiries, carried out through all the 
■different kinds of animals which are 
met with in nature, will lead us, not 
in one straight series, but by many 
roads, step by step, gradation by 
gradation, from man, at the summit, 
to specks of animated jelly at the 
bottom of the series. So that the 
idea of Leibnitz, and of Bonnet, that 
animals form a great scale of being, in 
which there are a series of gradations 
from the most complicated form to 
the lowest and simpest; that idea, 
though not exactly in the form in 
which it was propounded by those 
philosophers, turns out to be substan- 
tially correct. More than this, when 
biologists pursue their investigations 
into the vegetable world, they find 
tnat they can, in the same way, fol- 
low out the structure of the plant, 
from the most gigantic and compli- 
cated trees down through a similar 
series of gradations, until they arrive 
at specks of animated jelly, which 
they are puzzled to distinguish from 
those specks which they reached by 
the animal road. 
Thus, biologists have arrived at the 
eoaclusion that a fundamental uni- i 
formity of structure pervades the awi- 
mal and vegetable worlds, and that 
plants and animals differ from one 
another simply as diverse modifica- 
tions of the same great general plan. 
Again, they tell us the same story 
in regard to the study of function. 
They admit the large and inportant 
interval which, at the present time, 
separates the manifestations of the 
mental faculties, observable in the 
higher forms of mankind, and even 
in the lower forms, such as we know 
them, from those exhibited by other 
animals; but, at xhe same time, they 
tell us that the foundations, or rudi- 
ments, of almost all tire faculties of 
man are to be met with in the lower 
animals; that there is a unity of men- 
tal faculty as well as of bodily struc- 
ture, and that, here also, the differ- 
ence is a difference of degree and not 
of kind. I said “almost ail,” for a 
reason Among the many distinc- 
tions which have been drawn between 
the lower creatures ami ourselves, 
there is one which is hardly ever in- 
sisted on,* but which may be very 
fitly spoken of in a place so largely 
devoted to Art as that in which 
we are assembled. It is this, that 
while, among various kinds of ani- 
mals, it is possible to discover traces 
of all the other faculties of man, es- 
pecially the faculty of mimicry, yet 
that particular form of mimicry 
which shows itself in the imitation of 
form, either by modelling or by draw- 
ing, is not to be met with. As far as 
I know, there is no sculpture or mod- 
elling, and decidedly no painting or 
drawing, of animal origin. I men- 
tion the fact, in order that such 
comfort may be derived therefrom 
as artists may feel inclined to take. 
If what the biologists tell us is 
true, it will be needful to get rid of 
our erroneous conceptions of man, and 
of his place in nature, and to substi- 
tute right ones for them. But it is 
impossible to form any judgment as 
to whether the biologists are right or 
* I think that my friend Professor All- 
man was the first to draw attention to it. ON THE STUDY OF BIOLOGY. 
43 
wrong, unless we are able to appreci- 
ate the nature of the arguments which 
they have to offer. 
use of the image for the purposes of 
comparison ; but I will not proceed 
farther into that matter. 
One would almost think this to be 
a self-evident proposition. I wonder 
what a scholar would say to the man 
who should undertake to criticise a 
difficult passage in a Greek play, but 
■who obviously had not acquainted 
himself with the rudiments of Greek 
grammar. And yet, before giving 
positive opinions about these high 
questions of Biology, people not only 
do not seem to think it necessary to 
be acquainted with the grammar of 
the subject, but they have not even 
mastered the alphabet. You find 
criticism and denunciation showered 
about by persons, who not only have 
not attempted to go through the dis- 
cipline necessary to enable them to 
be judges, but who have not even 
reached that stage of emergence from 
ignorance in which the knowledge 
that such a discipline is necessary 
dawns upon the mind. I have had 
to watch with some attention—in fact 
I have been favored with a good deal ( 
of it myself—the sort of criticism 
with which biologists and biological 
teachings are visited. I am told every 
now and then that there is a “ bril- 
liant article”* in so-and-so, in which 
we are all demolished- I used to read 
these things once, but I am getting 
old now, and I have ceased to attend 
very much to this cry of “ wolf.” 
When one does read read any of these 
productions, what one finds generally, 
on the face of it, is that the brilliant 
critic is devoid of even the elements 
of biological knowledge, and that 
his brilliancy is like the light given 
out by the crackling of thorns under 
a pot of which Solomon speaks. 
So far as I recollect, Solomon makes 
Two things must be obvious: in 
the first place, that every man who 
has the imevests of truth at heart must 
earnestly desire that every well-found- 
ed and just criticism that can be made 
should be made; but that, in the sec- 
ond place, it is essential to anybody’s 
being able to benefit by criticism, that 
the critic should know what he is talk- 
ing about, and be in a position to 
form a mental image of the facts 
symbolized by the words he uses. If 
not, it is obvious in the case of a bi- 
ological argument, as it is in that of 
a historical or philological discussion, 
that such criticism is a mere waste of 
time on the part of its author, and 
wholly undeserving of attention on 
the part of those who are criticised] 
Take it then as an illustration of the 
importance of biological study, that 
thereby alone are men able to form 
something like a rational conception 
of what constitutes valuable criticism 
of the teachings of biologists.* 
* Some critics do not even take the 
trouble to read, I have recently been 
adjured with much solemnity, to state 
publicly why I have “changed my opin- 
ion ” as to the value of the palaeontolo- 
gical evidence ot the occurrence of evo- 
lution. 
To this my reply is, Why should 1, 
when that statement was made seven 
years ago ? An address delivered from 
the Presidential Chair of the Geological 
Society, in 1870, may be said to be a pub- 
lic document, inasmuch as it not only 
appeared in the Journal of that learned 
body, but was re-pubbshed, in 1873, in a 
volume of “ Critiques and Addresses,” to 
which ray name is attached. Therein 
will be found a pretty full statement of 
my reasons for enunciating two propo- 
sitions: (1) that “when we turn to the 
higher Vertelrrata, the results of recent 
investigations, however we may sift and 
criticise them, seem to me to leave a clear 
balance in lav or ot the evolution of living 
forms one from another;” and (2) that 
the case of the horse is one whica “will 
stand rigorous criticism.” 
Thus 1 do not see clearly in what way 
I can be said to have changed my opin- 
-1 ion, except in the way of intensifying it* 
* Galileo was troubled by a sort of 
people whom he called “ paper philoso- 
phers,” because they fancied that the true 
reading ot nature was to be detected by 
the collation of texts. The race is not 
extinct, but, as ot old, brings forth its 
“ winds of doctrine” by which the 
weathercock heads among us are much 
•Kercised. ON THE STUDY OF BIOLOGY. T 
Next, I may mention another bear- 
ing of biological knowledge—a mure 
practical one in the ordinary sense of 
the word. Consider the theory of in- 
fectious disease. Surely that is of 
interest to all of us. Kow, ti*3 theory 
of infectious disease is rapidly being 
elucidated by biological study. It is 
possible to produce, from among the 
lower animals, examples of devasta- 
ting diseases which spread in the same 
manner as our infectious disorders, 
and which are certainly and unmis- 
takably caused by living organisms. 
This fact readers it possible, at any 
rate, that that doctrine of the cau- 
sation of infectious disease which is 
known under the name of “the germ 
theory” may be well-founded; and, 
if so, it must needs lead to the most 
important practical measures in deal- 
ing with those terrible visitations. It 
may be well that the general, as well 
as the professional, public should have 
a sufficient knowledge of biological 
truths to be able to take a rational in- 
terest in the discussion of such prob- 
lems, and to see, what I think they 
may hope to see, that, to those who 
possess a sufficient elementary knowl- 
edge of Biology, they are not all 
quite open questions. 
Let me mention another important 
fore pass to the third question to 
! whWi I referred: Granted that Biol- 
; °gy something worth studying, 
■ what is the best way of studying it ? 
Here I must point out that, since 
Biology is a physical science, the 
method of studying it must needs be 
analogous to that which is followed 
in the other physical sciences. It has 
now long been recognized that, if a 
man wishes to be a chemist, it is not 
only necessary that he should read 
chemical books and attend chemical 
lectures, but that he should actually 
perform the fundamental experiments 
in the laboratory for himself, and 
thus learn exactly what the words 
which he finds in his books and hears 
from Ins teachers mean. If he does 
not do so, he may read till the crack 
of doom, but he will never know much 
about chemistry. That is what every 
chemist will tell you, and the physicist 
will do the same for his branch of 
science. The great changes and im- 
provements in physical and chemical 
scientific educat on, which have taken 
place of late, have all resulted from 
the combination of practical teaching 
with the reading of books and with 
the hearing of lectures. The same 
thing is true in Biology. Nobody 
will ever know anything about Bi- 
ology except in a dilettante “ paper- 
philosopher” way, who contents him- 
self with reading books on botany, 
zoology, and the like; and the reason 
of this is simple and easy to under- 
stand. It is that ail language is 
merely symbolical of the things of 
which it treats ; the more complicated 
the things, the more bare is the sym- 
bol, and the more its verbal definition 
requires to be supplemented by the 
information derived directly from the 
handling, and the seeing, and the 
touching of the thing symbolized; 
that is really what is at the bot- 
tom of the whole matter. It is 
plain common sense, as all truth, 
in the long run, is only common 
sense clarified. If you want a man to 
be a tea merchant, you don't tell him 
to read books about China or about 
tea, but you put him into a tea mer- 
practical illustration of the value of 
biological study. Within the last 
forty years the theory of agriculture 
has been revolutionized. The re- 
searches of Liebig, and those of our 
own Lawes and Gilbert, have had a 
bearing upon that branch of industry 
the importance of which cannot be 
overestimated ; but the whole of these 
new views have grown out of the 
better explanation of certain pro- 
cesses which go on in plants; and 
which, of course, form a part of the 
subject matter of Biology. 
1 might gc on multiplying these 
examples, but I see that the clock 
won’t wait for me, and I must there- 
when in consequence of the accumulation 
of similar evidence since 1870, I recently 
spoke of the denial ot evolution as not 
worth serious consideration. ON THE STUDY OF BIOLOGY 
45 
chant’s office, where he has the hand- 
ling, the smelling, and the tasting of 
tea. Without the sort of knowledge 
which can be gained only in this 
practical way, his exploits as a tea 
merchant will soon come to a bank- 
rupt termination. The “paper-philos 
ophers” are under the delusion that 
physical science can be mastered as 
literary accomplishments are ac- 
quired, but unfortunately it is not so. 
You may read any quantity of books, 
and you may be almost as ignorant 
as you were at starting, if you don’t 
have, at the back of your minds, the 
change for words in definite images 
whicn can only be acquired through 
the operation of your observing fac- 
ulties on the phenomena of nature. 
; 
ful to examine more than a compara- 
tively small number of animals and 
plants. 
Let me tell you what we do in 
the biological laboratory which is 
lodged in a building adjacent to this. 
There I lecture to a class of students 
daily for about fOur-and-a half months 
and my class have, of course, their 
text-books ; but the e sential part of 
the whole teaching, and that which I 
regard as really the most important 
part of it, is a laboratory for practi- 
cal work, which is simply a room 
with all the appliances needed for 
ordinary dissection. We have tables 
properly arranged in regard to 
light, microscopes, and dissect- 
ing instruments, and we work 
| through the structure of a certain 
| number of animals and plants. As, 
for example, among the plants, we 
take a yeast plant, a occus, a 
common mould, a Cham, a fern, and 
some flowering plant; among animals 
we examine such things as an Amoeba, 
a Vorticella, and afresh-water polype. 
We dissect a star fish, an ear h- 
worm, a snail, a squid, and a fresh- 
water mussel. We examine a lobster 
and a cray-lish, and a black-beetle. 
We go on to a common skate, a cod- 
fish, a frog, a tortoise, a pigeon, and a 
rabbit, and that takes us about all the 
tune we have to give. The purpose 
of this course is not to make skilled 
dissectors, but to give every studenta 
clear and definite conception,by means 
of sense-images, ot the characteristic 
structure of each of the leading modi- 
fications of the animal kingdom ; and 
that is perfectly possible, by going no 
further than the length of that list of 
forms which I have enumerated. If a 
man knows the structure of the ani- 
mals I have mentioned, he lias a clear 
and exact, however limited, appre- 
hension of the essential features of 
the organization of all those great 
divisions of the animal and vegetable 
kingdoms to which the forms 1 have 
mentioned severally belong. And it 
then becomes possible for him to read 
with profit; because every tune he 
meets with the name of a structure, 
It may be said “That is all very 
well, but you told us just now that 
there are probably something like a 
quarter of a million different kinds 
o. living and extinct animals and 
plants, and a human life could not 
suffice for the examination of one- 
fiftieth part of all these.” That is 
true, but then comes the great incon- 
venience of the way things are ar- 
ranged ; which is, that although 
there are these immense numbers of 
different kinds of living thing in ex- 
istence, yet they are built up, after 
ail, upon marvellously few plans. 
There are certainly more than 
100,000 species of insects, and yet 
anybody who knows one insect—if a 
properly chosen one—will be able to 
have a very fair conception of the 
structure of the whole. 1 do not 
mean to say to say that he will know 
that structure thoroughly, or as well 
as it is desirable he should know it; 
but he will have enough real knowl- 
edge to enable him to understand 
what he reads, to have genuine im- 
ages in his mind of those structures 
which become so variously modified 
in all the forms of insects he has not 
seen. In fact there are such things 
as types of form among animals and 
vegetables, and for the purpose of 
getting a definite knowledge of what 
constitutes the leading modifications 
of animal and plant life, it is not need- ON THE STUDY OF BIOLOGY. 
lie has a definite image in his mind of 
what the name means in the particu- 
lar creature he is reading about, and 
therefore the reading is not mere 
reading. It is not mere repetition of 
words ; but every term employed in 
the description, we will say, of ahorse, 
or of an elephant, will call up the 
image of the things he had seen in 
the rabbit, and he is able to form a 
distinct conception of that which he 
has not seen, as a modification of 
that which he has seen. 
answer. Nevertheless I must, at the 
risk of wearying you, say a word or 
tAvo upon the important subject of 
museums. Without doubt there are 
no helps to the study of Biology, or 
rather to some branches of it, which 
are, or may be, more important than 
natural history museums; but, in 
order to take this place in regard to 
Biology, they must be museums of the 
future. The museums of the present 
do not, by any means, do so much for 
us as they might do. Ido not Avish 
to particularize, but I dare say many 
of you, seeking knowledge, or in the 
laudable desire to employ a holiday 
usefully,have visited some great natu- 
ral history museum. You have Avalked 
through a quarter of a mile of ani- 
mals, more or less avcll stuffed, Avith 
their long names Avritten out under- 
neath them; and, unless your exjje- 
rience is very different from that of 
most people, the upshot of it all is 
that you leaAre that splendid pile Avith 
sore feet, a bad headache, and a gen- 
eral idea that the animal kingdom is 
a “mighty maze Avithout a plan.” 1 do 
not think that a museum which brings 
about this result does all that may be 
reasonably expected from such an in- 
stitution. What is needed in a collec- 
tion of natural history is that it 
should be made as accessible and as 
useful as possible, on the one hand to 
the general public, and on the other 
to scientific workers. That need is 
not met by constructing a sort of 
happy hunting-ground of miles of 
glass cases ; and, under the pretence 
of exhibiting everything, putting the 
maximum amount of obstacle in the 
way of those who Avish properly to see 
anything. 
I find this system to yield excellent 
results; and I have no hesitation 
whatever in saying that any one who 
has gone through such a course, at- 
tentively, is in a better position to 
form a conception of the great truths 
of Biology, especially of morphology 
(which is what we chiefly deal with), 
than if we merely read all the books 
on that topic put together. 
The connection of this discourse 
with the Loan Collection of Scientific 
Apparatus arises out of the exhibi- 
tion in that collection of certain aids 
to our laboratory work. Such of you 
as have visited that very interesting 
collection may have noticed a series 
of diagrams and of preparations illus- 
trating the structure of a frog. Those 
diagrams and preparations have been 
made for the use of the students 
in the biological laboratory. Similar 
diagrams and preparations illus- 
trating the structure of all the 
other forms of life we examine, 
are either made or in course of 
preparation. Thus the student has 
before him, first, a picture of the 
structure he ought to see; secondly, 
the structure itself worked out; and 
if with these aids, and such needful 
explanations and practical hints as a 
demonstrator can supply, he cannot 
make out the facts for himself in the 
materials supplied to him, he had 
better take to some other pursuit than 
that of biological science. 
What the public Avant is easy and 
unhindered access to such a collection 
as they can understand and appreci- 
ate ; and Avhat the men of science 
Avant is similar access to the materi- 
als of science. To this end the vast 
mass of objects of natural history 
should be divided into two parts— 
one open to the public, the other to 
men of science, every day. The 
former division should exemplify 
I should have been glad to have 
said a few words about the use of 
museums in the study of Biology,but I 
gee that my time is becoming short, 
«od I have yet another question to ON THE STUDY OF BIOLOGY. 
47 
all the more important and inter- 
esting forms of life. Explana- 
tory tablets should be attached to 
them, and catalogues containing 
clearly-written, popular expositions 
of the general significance of the ob- 
jects exhibited should be provided. 
The latter should contain, packed into 
a comparatively small space, in rooms 
adapted for working purposes, the 
objects of purely scientific interest. 
For example, we will say I am an 
ornithologist. Igo to examine a col- 
lection of birds. It is a positive nui- 
sance to have them stuffed. It is not 
only sheer waste, but I have to reckon 
with the ideas of the bird-stuffer, 
while, if I have the skin and nobody 
has interfered with it, I can form my 
own judgment as to what the bird 
was like. For ornithological pur- 
poses, what is needed is not glass 
cases full of stuffed birds on perches, 
but convenient drawers into each of 
which a great quantity of skins will 
go. They occupy no great space, and 
do not require any expend ture be- 
yond their original cost. But for the 
edification of the public, who want to 
learn indeed, but do not seek for mi- 
nute and technical knowledge, the 
case is different. What one of the 
general public walking into a collec- 
tion of birds desires to see is not all 
the birds that oan be got together. 
He does not want to compare a hun- 
dred species of the sparrow tribe side 
by side ; but he wishes to know what 
a bird is, and what are the great 
modifications of bird structure, and 
to be able to get at that knowledge 
easily. What will best serve his pur- 
pose is a comparatively small number 
of birds carefully selected, and artisti 
cally, as well as accurately, set up ; 
with their different ages, their nests, 
their young, their eggs, and their 
skeletons side by side ; and in accord- 
ance with the admirable plan which 
is pursued in this museum, a tablet, 
tolling the spectator in legible char- 
acters what they are and what they 
mean. For the instruction and recre- 
ation of the public such a typical col- 
lection would be of far greater value 
than any many-acred imitation of 
Noah’s ark. 
Lastly comes the question as to 
when biological study may best be 
pursued. Ido not see any valid rea- 
son why it should not be made, to at 
certain extent, a part of ordinary 
school training. I have long advo- 
cated this view, and I am perfectly 
certain that it can be carried out with 
ease, and not only with ease, but with 
very considerable profit to those who 
are taught; but then such instruction 
must be adapted to the minds and 
needs of the scholars. They used to 
have a very odd way of teaching the 
classical languages when I was a boy. 
Tiie first task set you was to learn the 
rules of the Latin grammar in the 
Latin language—that being the lan - 
guage you were going to learn! I 
thought then that this was an odd 
way of learning a language, but did 
not venture to rebel against the judg- 
ment of my superiors. Now, perhaps, 
I am not so modest as I was then, and 
I abow myself to think that it was a 
very absurd fashion. But it would 
be no less absurd, if we were to set 
about teaching Biology by putting 
into the hands of boys a series of de- 
finitions of the classes and orders of 
the animal kingdom, and making 
them repeat them by heart. That is 
so very favorite a method of teaching, 
that I sometimes fancy the spirit of 
the old classical system has entered 
into the new scientific system, in 
which case I would much rather that, 
any pretence at scientific teaching 
were abolished altogether. What 
really has to be done is to get into 
the young mind some notion of what 
animal and vegetable life is. In this 
matter, you have to consider practi-, 
cal convenience as well as other things.' 
There are difficulties in the way of a 
lot of boys making messes with slugs 
and snails ; it might not work in prac- 
tice. But there is a very convenient 
and handy animal which everybody 
has at hand, and that is himself f hhd 
it is a very easy and simple matter 
obtain common plants. Hence the 
general truths of anatomy and physi- 48 
ON THE STUDY OF BIOLOGY. 
ology can be taught to young people 
in a very real fashion by dealing with 
the broad facts of human structure. 
Such viscera as they cannot very well 
examine in themselves, such as hearts, 
lungs, and livers, may ne obtained 
from the nearest butcher’s shop. In 
respect to teaching something about 
the biology of plants, there is no prac- 
tical difficulty, because almost any of 
the common plants will do, and plants 
do not make a mess—at least they do 
not make an unpleasant mess; so 
that, in my judgment, the best form of 
Biology for teaching to very young 
people is elementary human physiol- 
ogy on the one hand, and the elements 
of botany on the other; beyond that 
I do not think it will be feasible to 
advance for some time to come. But 
then I see no reason why, in second- 
ary schools, and in the Science Cl as 
ses which are under the control of 
the Science and Art Department— 
and which I may say, in passing, 
have, in my judgment, done so very 
much for the diffusion of a knowledge 
of science over the country—we 
should not hope to see instruction in 
the elements of Biology carried out, 
not perhaps to the same extent, but 
still upon somewhat the same prin- 
ciple as here. There is no difficulty, 
when you have to deal with students 
of the ages of 15 or 16, in practicing 
a little dissection and in getting a 
notion of, at any rate, the four or five 
great modifications of the animal 
form ; and the like is true in regard 
to the higher anatomy of plants. 
While, lastly, to all those who are 
studying biological science with a 
view to their own edification merely, 
or with the intention of becoming 
zoologists or botanists; to all those 
who intend to pursue physiology— 
and especially to those who propose 
to employ the working years of their 
lives in the practice of medicine—l 
say that there is no training so fitted, 
or which may be of such important 
service to them, as the discipline in 
practical biological work which I have 
sketched out as being pursued in the 
laboratory hard by. 
I may add that, beyond all these 
different classes of persons who may 
profit by the study of Biology, there 
is yet one other. I remember, a 
number of years ago, that a gentle- 
man who was a vehement opponent 
of Mr. Darwin’s views and had writ- 
ten some terrible articles against 
them, applied to me to know what 
was the best way in which he could 
acquaint himself with the strongest 
arguments in favor of evolution. I 
wrote back, in all good faith and sim- 
plicity. recommending him to go 
through a course of comparative 
anatomy and physiology, and then to 
study development. I am sorry to 
say he was very much displeased, as 
people often are with good advice. 
Notwithstanding this discouragmgre- 
sult, I venture, as a parting word, to re- 
peat the suggestion, and to say to all 
the more or less acute lay and clerical 
“ paper-philosophers ”* who venture 
into the regions of biological contro- 
versy—Get a little sound, thorough, 
practical, elementary instruction in 
biology. 
* Writers of this stamp are fond of 
talking about the Baconian method. I 
beg them, therefore, to lay to heart these 
two weighty sayings of the herald of 
Modern Science: 
“ Syollogismus ex propositionibus con- 
stat, propositiones ex verbis, verba no- 
tionum tesserae sunt. Usque si notiones 
ipsae (id quod basis rei est) confusae sint et 
temere a rebus abstractae, nihil in iisquae 
superstruuntur est firmitudinis. “No- 
vum Organon,” ii. 14. 
“ Huic autem vanitati nonnulli ex 
modernis summa levitate ita indulserunt, 
ut in primo capitulo Geneeeos et in libro 
Job et aliis scripturis sacris, philoaoph- 
iam naturalem fundare conati sint; inter 
vivos qiuerentes mortuus. 
CONTENTS. 
I.—THREE LECTURES ON EVOLUTION; 
Lecture I.—The Three Hypotheses respecting the History op Nature . . 1 
Lecture 11.—The Hypothesis op Evolution. The Neutral and the Favorable 
Evidence 19 
Lecture Hl.—The Demonstrative Evidence op Evolution ...... S8 
11.-A LECTURE ON THE STUDY OF BIOLOGY . . 2fl HUMBOLDT LIBRARY 
Containing the Foremost Popular Scientific 
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Hoars : A series of Familiar Essays on Scien- 
tific Subjects. By Richard A. Proctor, F.R. A.S. 
Contents (in part); —The Earth a Magnet; the 
Secret of the North Pole ; Our Chief Timepiece 
Losing Time ; Tornadoes ; Influence of Marriage 
on the Death Rate ; Squaring the Circle ; the Use- 
fulness of Earthquakes; the Forcing Power of 
Rain, etc., etc. 
No. 3. Tine Forms of Water in Clouds and 
Rivers, Ice and Glaciers. By John Tindall, 
LL.D., F.R.S. (illustrated,). 
Contents (in pan) Oceanic Distillation ; Archi- 
tecture of Snow ; The Motion of Glaciers ; Icicles ; 
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No. 3. Physics and Politics:—An Appli- 
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trated ). 
Contents;— The Natural History of the Manlike 
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No. 5. Educations Intellectual, Moral 
and Physical. By Herbert Si enter. 
Contents What Knowledge is of Most Worth? 
Intellectual Education ; Moral Education ; Physi- 
cal Education. 
No, 6. Town Geology. By the Rev. 
Charles Kingsley, F.R.S., Canon of Chester. 
Contents:—The Soil of the Field ; the Pebbles 
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the Dissipation of Energy; the Position of Life ; 
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back to its true Principles. By C. Marcel. 
Contents Subdivision and Order of Study; 
the Art of Reading ; the Art of Hearing; the Art 
of Speaking ; the Art of Writing ; Mental Culture ; 
' Routine. 
No. 9. The Data of Etlilcs. By Herbert 
Spencer. 
Contents :—Conduct in General; Evolution of 
Conduct; Good and Bad Conduct; Ways of Judg- 
i mg Conduct; The Physical View ; The Biological 
View; the Psychological View; the Sociological 
View; Criticisms and Explanations; Relativity of 
Pains and Pleasures ; Egoism vs. Altruism; Ai- 
truism vs. Egoism ; Trial and Compromise ; Con- 
ciliation ; Absolute Ethics and Relative Ethics; 
the Scope of Ethics. 
No. 10. Tlie Theory of Sound in its Rela- 
tion to Music. By Prof. Pietro Blaserna, of 
tlie Royal University of Rome (illustrated). 
Contents (in part);— Periodic Movements, vibra- 
I tion ; Transmission of Sound ; Characteristics of 
j Sound, and difference between musical sound and 
noise ; Discords; Quality or timbre of musical 
| sounds ; Italian and German music, etc., etc. 
Nos. 11 and 13. The NatnraSlst on tho 
Sliver AmazonsA Record of Adventures. 
Habits of Animals, Sketches of Brazilian and 
Indian Life, and Aspects of Nature under lha. 
Equator, during eleven years of Travel. By 
Henry Walter Bates, F.R.S. 
*** One of the most charming books of travel ip 
our language. 
No, 13. Mind, and Hody; The Theories oj 
tucir Relation. By Alexander Bain, LL.D., 
Professor of Logic in the University of Aber- 
deen. 
Contents;—The Question Stated; Connection of 
Mind and Body; the Connection viewed as corre- 
spondence or concomitant variation ; General Laws 
of Alliance of Mind and Body: the Feelings and 
will ; tlie Intellect ; How are Mind and Body 
United ? History of the Theories of the Soul. 
No. 14. The Wonders* of the Heavens. 
By Camille Flammaßion (illustrated)'. 
Contents (in part):—The Heavens ; the Milky 
Way; Double, Multiple and Colored Suns; the 
Planets ; the Earth ; Plurality of Inhabited Worlds; 
Infinite Space; Constellations; The Sun; Comets; 
the Moon, etc., etc. 
No. 1.5, Longevity: the Means of Prolong, 
ing Life after the Middle Age. By John Gard- 
ner, M. D. 
Contents (in part):—ls the Duration of Life in 
any way within our power? Physiology of Ad- 
vanced Age ; Heredity ; Established Facts regard- 
ing Longevity, etc., etc. 
No. 16, Oil the Origin of Species ; or the 
Causes of the Phenomena of Organic Nature : A 
Course of Six Lectures. By Thomas H. Hux- 
ley, F.R.S. 
Contents:—Present Condition of Organic Nature, 
Past Condition of Organic Nature; Origination of 
Organic Beings ; Perpetuation of Living Beings; 
Conditions of Existence ; A Critical Examination 
of Mr. Darwin’s Great Work, 
No. 17. Progress: Its Law and Cause; 
with other disquisitions. By Herbert Sbencer. Coatents Progress ; the Physiology of Laugh- j 
ter; Origin and Functions of Music ; the Develop- 
ment Hypothesis; the Social Organism; the Use 
cf Anthropomorphism. 
No. IS|. Lessons in Electricity. By 
John Tyndall, F.R.S. (illustrated). 
Contents (in part);— The Art of Experiment; 
Electric Induction ; Lichtenberg's Figures; Elec- 
trics and Non-Electrics ; the Leyden Jar ; Physio- 
logical Effect of the Electric Discharge ; Atmos- 
pheric Electricity, etc., etc. 
No. 19. Familiar Essays on Scientific 
Subjects. By Richard A. Proctcr, F.R.A.S. 
Contents :—Oxygen in the Sun ; Sun-spot, Storm 
and Famine ; New ways of Measuring the Sun’s 
Distance ; Drifting Light-waves ; The new Star 
which faded into Star-mist; Star-grouping. 
No. 20, Tlie Romance of Astronomy. 
By R. Kalley Miller, M.A. 
Contents:—The Planets ; Astrology; The Moon ; 
the Sun ; the Comets ; Laplace’s Nebular Hypoth- 
esis ; the Stars ; the Nebul® ; Appendix. 
Mo. 21. ©n tlie Physical Basis of Fife, 
With other Essays. By Thomas H. Hux- 
ley, F.R.S. 
Contents:—Physical Basis of Life; Scientific 
Aspects of Positivism ; A Piece of Chalk ; Geolog- 
ical Contemporaneity ; A Liberal Education and 
where to find it. * 
No. 22. Seeing and Thinking. By Prof. 
William Kinguon Clifford, F.R.S. (illustrated). 
Contents:—The Eye and the Brain ; the Eye and 
Seeing ; the Brain and Thinking; On Boundaries 
in General. 
No. 23. Scientific Sophisms:—A Review 
of Current Theories concerning Atoms, Apes 
and Men. By Samuel Wainright, D.D. 
Contents:—The Right of Search ; Evolution : A 
Puerile Hypothesis ; Scientific Levity ; a House of 
Cards ; Sophisms ; Protoplasm ; the Three Begin- 
nings ; the Three Barriers; Atoms; Apes; Men; 
Anima Mundi. 
No. 24. Popular Scientific Eectures. 
By Prof. H. Helmholtz (illustrated). 
Contents:—The Relation of Optics to Painting, 
i. Form. 2. Shade. 3. Color. 4. Harmony of 
Color ; the Origin of the Planetary System ; 
Thought in Medicine ; Academic Freedom in Ger- 
man Universities. 
No. 25. Tlie Origin of Nations Co- 
mprising two divisions, viz.:—‘‘Early Civiliza- 
tions,” and “Ethnic Affinities.” By George 
Rawlinson, M.A., Camden Professor of Ancient 
History in Oxford University, England. 
Contents ;—Early Civilizations :•—Introduction ; 
Antiquityof Civilization in England ; Antiquity of 
Civilization at Babylon : Phoenician Civilization ; 
Civilizations of Phrygia, Lydia, the Troas, Assyria, 
Media, India, etc.; Civilization of’the British Celts ; 
Civilization of the Etruscans; Results of the In- 
quiry. Ethnic Affinities;— Chief Japhetic Races; 
Subdivisions of the Japhetic Races ; Chief Hametic 
Races .‘ Subdivisions of Cush ; Subdivisions of Miz- 
raim and Canaan ; the Semitic Races ; Subdivis- 
ions of the Semitic Races. 
No. 26. The Evolutionist at Eargie. By 
Grant Allen. 
Contents (in part):—Microscopic Brains ; Slugs 
and Snails; Butterfly Psychology ; In Summer 
Fields; Speckled Trout; Origin of Walnuts ; Dogs 
and Masters, etc., etc. 
No. 27. Tlie History of Eandholding 
in England. By Joseph Fisher, F.R.H.S. 
Contents (in part):—The Aborigines ; the Scan- 
dinavians ; the Plantagenets ; the Stuarts ; the Ro- 
mans ; the Normans; the Tudors; the House of 
Brunswick ; Land and Labor, etc., etc. 
No. 28. Fashion in Deformity, as Illus- 
trated in the Customs of Barbarous and Civil- 
ized Races. By William Henry Flower, F.R.S. 
(illustrated). To which is added Manners 
and Fasllion. By Herbert Spencer. 
Contents (in part):—Fashions in Coiffure ; Tat- 
tooing; Deforming the Teeth ; Deforming the 
Feet; Eradicating the Eyebrows ; Ornaments for 
the Nose, Ears, Lips; Compressing the Skull; 
Effects of Tight Lacing, etc., etc. 
No. 29. Facts and. Fictions of Zoology, 
By Andrew Wilson. Ph.D. (illustrated). 
Contents Zoological Myths ; the Sea Serpents 
of Science; Some Animal Architects; Parasites 
and Their Development ; What I saw in an Ant’s 
Nest. 
Nos. 30 and 31, On tlie Study of. 
Words. By Richard Chenkvix Trench, D.D. 
Contents :—lntroduction ; the Poetry in Words ; 
the Morality in Words ; the History in Words ; 
the Rise of New Words ; the Distinction of Words ; 
the Schoolmaster’s use of Words. 
No. 32. Hereditary Traits, and other 
Essays. By Richard A. Proctor, r'.R.A.S. 
Contents Hereditary Traits ; Artificial Som- 
nambulism ; Bodily Illness as a Mental Stimulant; 
Dual Consciousness. 
No. 33. Vignettes from Nature. By 
Grant Allen. 
Contents (in part) :—Fallow Deer ; the Heron’s 
Haunt; Wild Thyme ; the Fall of the Leaf ; the 
Hedgehog’s Hole; Seaside Weeds; the Donkey's 
Ancestors. 
No. 34. Tlie Philosophy of Style. By 
Herbert Spencer. To which is added :~The 
Mother Tongue. By Alexander Bain, 
LL.D. 
Contents‘The Principle of Economy applied 
to words- Effect of Figurative Language Ex- 
plained; Arrangement of Minor Images in build- 
ing up a thought; The Superiority of Poetry to 
Prose explained; Causes of Force in Language 
which depend upon Economy of the Mental Sensi- 
bilities ; the Mother Tongue. 
No. 35. Oriental Religions. Edited by 
Rev. John Cairo, D.D., President of the Uni- 
versity of Glasgow. 
Contents : Brahmanism ; Buddhism ; Confu- 
cianism ; Zoroaster and the Zend Avesta. 
No, 36. Eectures on Evolution, wita an 
Appendix on the Study of Biology. By 
Thomas H. Huxley, ILK S. (illustrated). 
Contents:—The Three Hypotheses respecting 
the History of Nature; the Hypothesis of Evolu- 
tion—the Neutral and Favorable Evidence ; the 
Demonstrative Evidence of Evolution; the Study 
of Biology. 
No. ST, Six Eectures on liight. By John 
Tyndall, E.R.S. (illustrated). 
Contents: Introductory; Origin of Physical 
Theories; Relation of Theories to Experience- 
Chromatic Phenomena produced bv Crystals > 
Range of Vision and Range of Radiation ; Spec- 
trum Analysis. 
Nos. 38 and 39. Geological Slcetclies 
at Home and Abroad ; in two Parts, each 
complete in itself. By Archibald Geikie, 
F.R.S. 
Contents : Part IMy first Geological Excur- 
sion ; “ The Old Man of Hoy ” ; the Baron’s Stone 
of Killochan ; the Colliers of Carrick ; Among the 
Volcanoes of Central France ; the Old Glaciers of 
Norway and Scotland; Rock-Weathering meas- 
ured by Decay of Tombstones. Part II: A Frag- 
ment of Primeval Europe; In Wyoming; The 
Geysers of the Yellowstone ; the Lava fields of 
Northwestern Europe ; the Scottish School of 
Geology ; Geographical Evolution ; the Geologi- 
cal influences which have affected the course of 
British History. 
No. 40. Tlie Scientific Evidence of Or- 
ganic Evolution. By George J. Romanes, 
r.R.S. 
Contents (in part);— The Argument from Classi- 
fication—from Morphology or Structure—from 
Geology—from Geographical Distribution—from 
Embryology, etc., etc. 
No. 41. Current Discussions in Sci- 
ence. By W. M. Williams, F.C..S. 
Contents (in part): The Fuel of the Sun; Ori- 
gin of Lunar Volcanoes; Aerial Exploration of 
the Arctic Regions; The Air of Stove-heated 
Rooms, etc., etc. 
No. 42. History of tlie Science of Poli- 
tics. By Frederick Pollock. 
Contents: The Place of Politics in Human 
Knowledge ; The Classic Period—Pericles—Soc- 
rates—-Plato—Aristotle, etc.; the Medieval Period r-the Papacy and the Empire ; Beginning of the 
Modern Period—Machiavelli—Hobbes ; the Mod- 
ern Period—Locke—Hooker—Blackstone—Hume— 
Montesquieu—Burke ; the Present Century—Ben- 
tham—Austin—Kant—Savigny—Herbert Spencer. 
Wo. 43. Darwin and Humboldt, tlielr 
Lives and Works:—Contains a senes of 
notices of Darwin, by Huxley, Romanes, Geikie, 
Thiselton Dyer; also the late Prof. Agassiz’s, 
Centennial Address on the Life and Work of 
Alexander von Humboldt. 
Nos. 44 and 45. The Dawn of History : 
an introduction to Pre-Histone Study. Edited 
by C. P. Keaky, M.A., of the British Museum. 
In two Parts. 
Contents of Part I: Earliest Traces of Man ; the 
Second Stone Age; the Growth of Languages; 
Families of Languages; the Nations of the Old 
World ; Early Social Life ; the Village Community. 
Contents of Part II; Religion ; Aryan Religion ; 
the Other World'; Mythologies and Folk Talcs; 
Picture Writing ; Phonetic Writing ; Conclusion. 
No. 46. The Diseases of Memory. By 
Th. Ribot. (Translated from the French by 
J. Fitzgerald.) 
Contents:—Memory as a Biological Fact ; Gen- 
eral Amnesia; Partial Amnesia; Exaltation of 
Memory, or Hypermiesia ; Conclusion. 
No. 47. The ( liiliiliood of Heligions. 
By Edward Clodd, F.R.A.S. 
Contents (in part):—Legends of the Past about 
Creation ; Creation as told by Science ; Legends 
of the Past about Mankind ; Ancient and Modern 
Hindu Religions, etc., etc. 
No. 48, Life in Nature. By James Hinton, 
Author of " Man and his Dwelling Place.” 
Contents (in part).—Function; Living Forms; 
Is Life Universal? Nutrition; Nature and Man; 
the Life of Man, etc., etc. 
No. 49. The Sun;—its Constitution; its Phe- 
nomena ; its Condition. By Nathan T. Carr, 
, LL.D., Judge of the Ninth Judicial Circuit of 
Indiana. 
Contents (in part):—The Sun’s Atmosphere ; the 
Chromosphere; the Photosphere; Production of 
the Sun’s Spots ; the Question of the Extinction of 
the Sun, etc., etc. 
Nos. 50 and 51. Money and tlie Mech- 
anism of Exchange; By Prof. W. Stan- 
ley Jevons, F.R.S. 
Contents (in part):—The Functions of Money; 
Early History of Money ; the Metals as Money ; 
Principles of Circulation ; Promissory Notes ; the 
Banking System; the Clearing House; Quantity 
of Money needed by a Nation, etc., etc. 
No. 52. The Diseases of the Will, By 
Th. Ribot. (Translated from the French by J. 
Fitzgerald.) 
Contents The Question Stated ; Impairment 
of the Will—Lack of Impulsion—Excess of Impul- 
sion ; Impairment of Voluntary attention ; Caprice ; 
Extinction of the Will ; Conclusion. 
No. 53. Animal Automatism, and Other 
Essays. By Prof. T. H. Huxley, F.R.S. 
Contents:—Animal Automatism; Science and 
Culture ; Elementary Instruction in Physiology; 
the Border Territory between Animals and Plants ; 
Universities. Actual and Ideal. 
No. 54. The Birth and Growth of 
Myth. By Edward Clodd, F.R.A.S. 
Contents (in part) :—Nature as viewed by Primi- 
tive Man ; Sun and Moon in Mythology ; the Hindu 
Sun and Cloud Myth ; Demonology; Beast Fables ; 
Totemism, etc., etc. 
No. 55. The Scientific Basis of Morals, 
and Other Essays. By William Kingdon 
Clifford, F.R.S. 
Contents ;—Scientific Basis of Morals , Right and 
Wrong; the Ethics of Belief; the Ethics of Re- 
union. 
Nos. 5G and 57. Illusions; A Psy- 
chological Study. By James Sully. 
Contents:—The Study of Illusion ; Classification 
of Illusions; Illusions of Perception; Dreams; 
Illusions of Introspection ; Other Quasi-Presenta- 
tive Illusions ; Illusions of Memory ; Illusions of 
Belief. 
Nos. 58 and 59 (two double numbers, accents 
each). The Origin of Species. By Charles 
Darwin. 
*** This is Darwin’s famous work complete, 
with index and glossary. 
No. 60. The Childhood Of the World. 
By Edward Clodd, r .re. a.s. 
Contents (in part) -.—Man’s First Wants, Man’s 
First Tools, Fire, Dwellings, Use of Metals; Lan- 
guage, Writing, Counting, Myths about Sun and 
Eclipses ; Ideas about the Soul, Be- 
lief in Witchcraft, Fetichism, Idolatry, etc., etc. 
No. Gl. Miscellaneous Essays. By Rich- 
ard A. Proctor. 
Contents:—Strange Coincidences; Coincidences 
and Superstitions; Gambling Superstitions ■„ 
Learning Languages ; Strange Sea-Creatures; the- 
Origin of Whales ; Prayer and Weather. 
No, 62 (Double number, 30 cents). The Be* 
ligions of the Ancient World. 
Contents:—Religions of the Ancient Egyptians, 
ancient Iranians, Assyrians, Babylonians, ancient 
Sanskritic Indians, Phoenicians, Carthaginians, 
Etruscans, ancient Greeks and ancient Romans. 
No. 63. Progressive Morality. By 
Thomas Fowler, F.S.A., President of Corpus 
Christ! College, Oxford. 
Contents:—The Sanctions of Conduct; th® 
Moral Sanction, or Moral Sentiment ; Analysis 
and Formation of the Moral Sentiment; the Moral 
Test; Examples of the practical applications of 
the Moral Test. 
No, 64. The Distribution of Life, By 
Alfekd Russel Wallace and W. T. Thiselton 
Dyer, 
Contents (in part):—Geographical Distribution 
of Land Animals; Distribution of Marine Ani- 
mals ; Relations of Marine with Terrestrial Zoolog- 
ical Regions; Distribution of Vegetable Life; 
Northern, Southern, Tropical Flora, etc., etc. 
No* 65* Conditions c 4 Mental Devel- 
opment, and Other Essays. By William 
Kingdon Clifford, F.R.S. 
Contents .-—Conditions of Mental Development; 
Aims and Instruments of Scientific Thought; 
Atoms ; The First and the Last Catastrophe. 
No. 66. Technical Education, rnd other 
Essays. By Thomas H. Huxley, F.R.S. 
Contents:—Technical Education; The Connec- 
tion of the Biological Sciences with Medicine; 
Joseph Priestley; On Sensation and the Unity of 
Structure of the Sensiferous Organs; On Certain 
Errors respecting the Structure of the Heart at- 
tributed to Aristotle. 
No. 67. The Black Death; An account of 
the Great Pestilence of the 14th Century. By 
J. F. C. Hecker, M.D. 
Contents:—General Observations ; the Disease; 
Causes—Spread, Mortality; Moral Effects ; Physi- 
cians ; Appendix. 
No. 68 (Special Number, 10 cents). Three 
Essays, viz.: Laws, and the Order of their 
Discovery ; Origin of Animal Worship ; Politi- 
cal Fetichism. By Herbert Spencer. 
No. 69 (Double Number, 30 cents). Fetloh- 
ism: A Contribution to Anthropology and the 
History of Religion. By Fritz Schultze, Ph D. 
Translated from the German by J. Fitzgerald, 
M.A. 
Contents ;—The Mind of the Savage ; Relation 
between the Savage Mind and its Object; Fetich- 
ism as a Religion ; Various Objects of Fetich Wor- 
ship;— The Highest Grade of Fetichism; Aim of 
Fetichism. Wo. TO. Essays, Speculative and Prac- 
tical. By Herbert Spencer. 
Contents:—Specialized Administration; “The 
Collective Wisdom;” Morals and Moral Senti- 
ments ; Reasons for Dissenting from the Philos- 
ophy of Comte ; What is Electricity ? 
No, 71. Anthropology, By Daniel Wil- 
son, LL.D. 
Contents :—Scope of the Science ; Man’s Place in 
Nature ; Origin of Man ; Races of Mankind ; An- 
tiquity of Man Language ; Development of Civ- 
ilization. 
No. 72. The Dancing Mania of the 
Middle Ages. By J. F. C. Hecker, M.D. 
Contents (in part):—The Dancing Mania in Ger- 
many and the Netherlands ; The Dancing Mania in 
Italy ; The Dancing Mania in Abyssinia. 
No. 73. Evolution In History, lan- 
guage, and Science. Lectures delivered at 
the London Crystal Palace School of Art, Sci- 
ence, and Literature. 
Contents:—The Principle of Causal Evolution; 
Scientific Study of Geography ; Hereditary Ten- 
dencies ; Vicissitudes of the English Language. 
Nos. 74, 75, 76, 77. The Descent of 
Man, and Selection In Delation to 
Sex. By Charles Darwin. 
*#* Price, Parts 74, 75, 76, fifteen cents each ; 
No. 77 (double number), thirty cents; the entire 
work, seventy-five cents. 
No. 78. Historical Sketch of the Dis- 
tribution of hand lit England. By 
Prof. Wm. Lloyd Birkbeck, Cambridge Uni- 
versity. 
Contents;—Anglo-Saxon Agriculture ; Origin of 
Land Properties; Saxon Law of Succession to 
Land ; Norman Law of Succession ; Inclosure of 
Waste Lands, etc. 
No. 79. Scientific Aspects of Some Fa- 
miliar Things. By W. M. Williams, 
F.R.S., F.C.S. 
Contents;—Social Benefits of Paraffin; Forma- 
tion of Coal; Chemistry of Bog Reclamation ; The 
Coloring of Green Tea; “Iron Filings” in Tea; 
Origin of Soap ; Action of Frost on Building Ma- 
terials, etc.; Fire-Clay and Anthracite ; Rumford’s 
Cooking-Stoves; Stove-heated Rooms; Domestic 
Ventilation. 
No. 80. Charles Darwin ; His Fife and 
Work, By Grant Allen. (Double Number, 
30 cents.) 
No. 81. Tiie Mystery of Matter. Also 
The Philosophy of Ignorance. By J. 
Allanson Picton. 
No. 82. Illusions of the Senses and 
Other Essays. By Richard A. Proctor. 
Contents:—lllusions of the Senses; Animals of 
the Present and the Past ; Life in Other Worlds ; 
Earthquakes ; Our Dual Brain ; A New Star in a 
Star Cloud ; Monster Sea-Serpents; Origin of 
Comets. 
No. 83. Profit-Sharing Between La- 
bor and Capital. By Sedley Taylor. 
Contents:—Profit-Sharing in the Maison Le- 
flaire ; Profit-Sharing in Industry ; Profit-Sharing 
in the Paris-Orleans R.R. Co. ; Profit-Sharing in 
Agriculture ; An Irish Experiment ; Profit-Shar- 
ing in Distributive Enterprise. 
No. 84. Studies of Animated Nature. 
By W. S. Dallas. 
Contents Bats ; Dragon-Flies; The Glow- 
Worm and other Phosphorescent Animals; Minu.i 
Organisms. 
No. 85. The Essential Nature of Re- 
ligion, By J. Allanson Picton. 
Contents: Religion and Freedom of Thought; 
Evolution of Religion; Fetichism; Nature-Wor- 
ship; Prophetic Religions; Religious Dogma; The 
Future of Religion. 
No. 86. The Unseen Universe. Also, 
The Philosophy of the Pure Science; 
By Wm. Kingdon Clifford, F.R.S. 
Contents;—The Unseen Universe; Philosophy of 
the Pure Sciences ; Statement of the Question ; 
Knowledge and Feeling; Postulates of the Science 
of Space; The Universal Statements of Arithmetic. 
No. 87. The Morphine Habit (Mor- 
phlnomania.) With Four oilier 
JLectures. By Prof B. Ball, M.D. 
Contents General Description of Morphino- 
mania; Effects of the Abuse of Morphine; Effects 
of Abstinence; The Borderland of Insanity, Pro- 
longed Dreams ; Cerebral Dualism ; Insanity in 
Twins. 
No. 88. Science and Crime, and other 
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No. 89. The Genesis of Science. By 
Herbert Spencer. 
To which is added : The Coming of Age of “ The 
Origin of Species ” By T. H. Huxley. 
No. 90. Notes on Earthquakes : with 
other Essays. By Richard A. Proctor. 
Contents Notes on Earthquakes ; Photograph- 
ing Fifteen Million Stars; Story of the Moon; 
The Earth’s Past; Story of the Earth ; Falls of 
Niagara; The Unknowable; Sun-Worship; Her- 
bert Spencer on Priesthoods ; Star of Bethlehem 
and a Bible Comet; An Historical Puzzle ; Galileo, 
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the Ninth Century; The First Universities; Saler 
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Oxford and Cambridge; University of Prague, 
etc. 
No. 92. Formation of Vegetable 
Mould Through the Action of Earth- 
Worms, with Observations on their 
Habits. By Charles Darwin. (.Double Num- 
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No. 93. Scientific Methods of Capital 
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(Price ten cents.) 
Contents- General Review of the Subject; 
Death by Hanging; by Electricity; by Subcuta- 
neous Injection of Morphine; by Chloroform; by 
Prussic Acid; Objections. Appendix. Infliction 
of the Death Penalty, By Park Benjamin. 
No. 94-. The Factors of Organic Evolution. By Herbert Spencer. 
No. 95. The Diseases of Personality. By Th. Ribot. (Translated 
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and Grant Allen boldt Library Catalogue 
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53. Annual Automatism, etc. 
w. Technical Education, etc. 
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46, The Diseases of Memory. 
52. The Diseases of the Will. 
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58. ) ThrOkigin of Species. (Two Double 
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erna. 
11. | The Naturalist on the River Amazons. 
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Camille Flammaeion. 
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20. Romance of Astronomy. F. K. Miller. 
23. Scientific Sophisms. S Wain WRIGHT. 
*4. Scientific Lectures (Illustrated). Prof. 
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27. Landholding in England. Jos. Fisher. 
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H. Flower. 
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A. Wilson. 
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-31. ( nkvix Trench. 
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No. 
22. Seeing and Thinking. 
55. The Scientific Basis of Morals, etc. 
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of the 14th Century. J. F. C. Heckssl 
(Ready April 10, 1885.) CROSBY’S 
VITALIZED PHOSPHITES, 
COMPOSED 
OF THE 
NERVE-GIVING 
PRINCIPLES 
OF THE 
OX BRAIN 
AND THE 
EMBRYO 
OF THE 
WHEAT AND OAT 
This is a standard preparation with all physicians who treat nervous or 
mental disorders. It is not a secret, the formula is on every label. Its 
careful chemical composition has been superintended for twelve years by a 
Professor of Materia Medica, and its correct analysis vouched for by a Pro- 
fessor of Chemistry. Physicians alone have prescribed over a million bot 
des, curing nervous derangements and debility. 
it aids in the bodily, and wonderfully in the mental, growth of children. 
It cures fretfulness and sleeplessness. 
By its special tonic effect upon the nerves, and its vitalizing influence 
on the blood of young persons, it brightens the eyes and gives good color to 
the lips; it ensures a soft, smooth skin, glossy hair and handsome nails, so 
that these become an inheritance in later years. It feeds the brain and 
thus strengthens the intellect, so that study and deep mental application may 
be a pleasure, not a toil. 
It is used as a special brain tonic by all the best minds of this and othei 
countries. 
It strengthens the powers of digestion, is a positive cure for night- 
sweats, and prevents consumption. 
“It amplifies bodily and mental powers to the present generation anA 
‘ proves the survival of the fittest,’ to the next.” 
“ There is no other Vital Phosphite; none that is extracted from living 
vegetable and animal tissues.” 
Send for Circular. 
F. CROSBY CO., 
56 West 25TH Street, New York.