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1 2 3
1
2
3
4
5
6
THE DAWN OF LIFE.
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THE DAWN OF LIFE;
BEING THE
i .
|jist0rn 0f t^-e ©Ikst Jlnoton fossil ^^^^mainS;
AND
■a
THEIR RELATIONS TO GEOLOGICAL TIME
AND TO THE DEVELOPMENT OF
>: ' THE ANIMAL KINGDOM.
J. W. DAWSON, LL.D., F.R.S., F.G.S., Etc.,
PRINCIPAL AND VICE-CHANCELLOR OF M'GILL UNIVERSITY, MONTREAL ;
AUTHOR OF
"ARCHAU," "ACADUN GEOLOGY," "THE STORY OF
THE EARTH AND MAN," ETC. '
MONTREAL:
DAWSON BROTHERS.
MPCCCL^XV.
S
STo tbc lllemorn of
SIR WILLIAM EDMOND LOGAN,
LL.D., F.R.S., F.G.S.,
THIS WORK 18 DEDICATED,
Not merely as a fitting acknowledgment of his long
and successful labours in the geology of those most
ancient rocks, first named by him Laurentian, and
which have afforded the earliest known traces of the
beginning of life, but also as a tribute of sincere
personal esteem and regard to the memory of one
who, while he attained to the highest eminence as a
student of nature, was also distinguished by his
patriotism and public spirit, by the simplicity and
earnestness of his character, and by the warmth of
his friendships.
■*i^^turir3?Bweifsw*)»'::.=t*-ai-.--»:
PEEFACE.
An eminent German geologist has characterized the
discovery of fossils in the Laurentian rocks of Canada
as "the opening of a new era in geological science."
Believing this to be no exaggeration, I have felt it to
be a duty incumbent on those who have been the
apostles of this new era, to make its significance as
widely known as possible to all who take any interest
in scientific subjects, as well as to those naturalists
and geologists who may not have had their atten-
tion turned to this special topic.
The delivery of occasional lectures to popular
audiences on this and kindred subjects, has convinced
me that the beginning of life in the earth is a theme
having attractions for all intelligent persons ; while
the numerous inquiries on the part of scientific"
students with reference to the fossils of the Eozoic
age, show that the subject is ye^ far from being
familiar to their minds. I offer no apology therefore
for attempting to throw into the form of a book
accessible to general readers, what is known as to
■I
Vlll
PREFACE.
the dawn of life, and cannot doubt that the present
work will meet with at least as much acceptance as
that in which I recently endeavoured to picture the
whole series of the geological ages.
I have to acknowledge my obligations to Sir W.
E. Logan for most of the Laurentian geology in
the second chapter, and also for the beautiful map
which he has kindly had prepared at his own ex-
pense as a contribution to the work. To Dr. Car-
penter I am indebted for much information as to
foraminiferal structures, and to Dr. Hunt for the
chemistry of the subject. Mr. Selwyn, Director of
the Geological Survey of Canada, has kindly given
me access to the materials in its collections. Mr.
Billings has contributed specimens and illustrations
of Palaeozoic Protozoa; and Mr. Weston has aided
greatly by the preparation of slices for the micro-
scope, and of photographs, as well as by assistance
in collecting.
J. W. D.
McGiLL College, Montreal.
April, 1875.
CONTENTS.
4
Chapter I. Intkoductory ' .
Chapter II. The Laurentian System
Notes : — Logan on Structure o? Laurentian ; Hunt
ON Life in the Laurentian; Laurentian Graphite
Western Laurentian; Metamorpuism .
Chapter IIL The History of a Discovery .
Notes: — Logan on Discovery of Eozoon, and on
Additional Specimens
Chapter IV. What is Eozoon ? . . . .
Notes :— Original Description; Note by Dr. Car
PENTER ; Specimens from Long Lake ; Additional
Structural Facts
Chapter V. Preservation of Eozoon
Notes:— Hunt on Mineralogy of Eozoon; Silici
fied Fossils in Silurian Limestones; Minerals
associated with Eozoon ; Glauconites .
Chapter VI. Contemporaries and Successors
Notes :— On STROMATOPORiDiE ; Localities of Eozoon
Chapter VII. Opponents and Objections
Notes : — Objections and Keplies ; Hunt on
Chemical Objections ; Reply by Dr. Carpenter 184i
Chapter VIII. The Dawn-Animal as a Teacher in
Science 207
Appendix 2135
Index '. . .237
PAGE
1
24
35
48
69
76
93
115
127
165
169
> \
II
III
ly
V
V]
VI]
VII]
FIG.
1. G
2. L
3. S
4. L
5. S
6. S
7. E
8,9.
10. C
11. N
12. A
13. A
LIST OF ILLUSTEATIONS.
r
i
FULL PAGE ILLUSTRATIONS.
TO PACS
PAQK
I. Cape Trinity, from a Photograph {Frontispiece).
II. Map of the Laurentian Region on the River Ottawa 7
III. "Weathered Specimen of Eozoon, from a Photograph 35
IV. Restoration of Eozoon 59
V. Nature -print of Eozoon 93
VI. Canals op Eozoon, Magnified, from Photographs 127
VII. Nature -print op Large Laminated Specimen . 1G9
VIII. Eozoon with Chrysotile, etc 207
* 'if
•1 -ft
WOODCUTS.
VIG.
1. General Section
2. Laurentian Hills
3. Section of Laurentian
4. Laurentian Map
5. Section at St. Pierre
6. Sketch of Rocks at St.
7. Eozoon from Burgess
8. 9. Eozoon from Calumet
10. Canals of Eozoon
11. NuMMULiNE Wall
12. Amceba
13. Actinophrys.
ERRE
PA OB
9
11
13
16
22
22
36
39
41
43
60
60
■■•■ ■?
xu
LIST OF ILLUSTRATIONS.
II*
no.
14. Entosolenia.
15. BiLOCULINA .
16. POLYSTOMELLA
17. POLYMOivrniNA
18. ARCILEOSPIIERINi*:
19. nummulites .
20. Calcarina .
21. fokaminiferal rock-builders
21a. Casts of Cells op Eozoon
22. Modes op Mineralization .
23. Silurian Organic Limestone
24. Wall op Eozoon penetrated with Canals
25. Crinoid Infiltrated with Silicate
26. Shell Infiltrated with Silicate
27. Diagram of Proper Wall, etc.
28. 29. Casts of Canals
30. Eozoon from Tudor
31. Acervuline Variety of Eozoon,
82, 33, 34. ARCHiEOSPHERINiE
35. Annelid Burrows
36. ARCIIiEOSPHERINiS
37. Eozoon Bavaricum
38, 39, 40. ARCHiEOCYATHUS
41. ArchjEocyathus (Structure of)
42. Strom ATOPORA
43. Stromatopora (Structure of)
44. Caunopora ....
45. C(enostroma ....
46. Receptaculites .
47. 48. Receptaculites (Structure of)
49. LAMiNiE OF Eozoon
PACK
02
62
62
63
67
73
73
75
92
96
98
98
103
104
106
107
111
135
137, 138
140
148
149
152, 153
154
157
158
159
160
162
163
176
THE DAWN OF LIFE,
CHAPTER I.
INTRODUCTORY.
Every one has heard of, or oug^lit to haye heard of,
Eozoon Ganadense, the Canadian Dawn^animal, the sole
fossil of the ancient Laurentian rocks of North
America, the earliest known representative on our
planet of those wondrous powers of animal life which
culminate and unite themselves with the spirit-world
in man himself. Yet few even of those to whom the
name is familiar, know how much it implies, and how
strange and wonderful is the story which can be
I evoked from this first-born of old ocean.
No one probably believes that animal life has been
an eternal succession of like forms of being. We are
familiar with the idea that in some way it was intro-
duced; and most men now know, either from the
[testimony of Genesis or geology, or of both, that the
lower forms of animal life were introduced first, and
Ithat these first living creatures had their birth in the
[waters, which are still the prolific mother of living
[things innumerable. Further, there is a general im-
[pression that it would be the most appropriate way
that the great procession of animal existence should
I II
2
THE DAWN OP LIFE.
commence with tlie humblest types known to us, and
should march on in successive bands of gradually
increasing dignity and power, till man himself brings
up the rear.
Do we know the first animal ? Can we name it,
explain its structure, and state its relations to its suc-
cessors ? Can we do this by inference from the suc-
ceeding types of being ; and if so, do our anticipations
agree with any actual reality disinterred from the
earth's crust ? If we could do this, either by inference
or actual discovery, how strange it would be to know
that we had before us even the remains of the first
creature that could feel or will, and could place itself
in vital relation with the great powers of inanimate
nature. If we believe in a Creator, we shall feel it a
solemn thing to have access to the first creature into
which He breathed the breath of life. If we hold
that all things have been evolved from collision of
dead forces, then the first molecules of matter which
took upon themselves the responsibility of living, and,
aiming at the enjoyment of happiness, subjected them-
selves to the dread alternatives of pain and mortality,
must surely evoke from us that filial reverence which
we owe to the authors of our own being, if they do
not involuntarily draw forth even a superstitious
adoration. The veneration of the old Egyptian for
his sacred animals would be a comparatively reason-
able idolatry, if we could imagine any of these animals
to have been the first that emerged from the domain
of dead matter, and the first link in a reproductive
c
INTRODUCTORY.
8
) us, and
radually
£ brings
lamo it,
) its suc-
the suc-
cipations
[rem the
inference
to know
the first
lace itself
inanimate
. feel it a
iture into
we hold
fllision of
Iter which
mg, and,
ed them-
ortality,
ce which
they do
lerstitious
(tian for
reason-
animals
|e domain
'oductive
chain of being that produced all the population of the
world. Independently of any such hypotheses, all
students of nature must regard with surpassing in-
terest the first bright streaks of light that break on
the long reign of primeval night and death, and pre-
sage the busy day of teeming animal existence.
No wonder then that geologists have long and
earnestly groped in the rocky archives of the earth in
search of some record of this patriarch of the animal
kingdom. But after long and patient research, there
still remained a large residuum of the oldest rocks,
destitute of all traces of living beings, and designated
by the hopeless name " Azoic,'' — the formations desti-
tute of f-emains of life, the stony records of a lifeless
world. So the matter remained till the Laurentian
rocks of Canada, lying at the base of these old Azoic
formations, afi'orded forms believed to be of organic
origin. The discovery was hailed with enthusiasm by
those who had been prepared by previous study to re-
ceive it. It was regarded with feeble and not very
intelligent faith by many more, and was met with
half-concealed or open scepticism by others. It pro-
ducv^d a copious crop of descriptive and controversial
literature, but for the most part technical, and con-
fined to scientific transactions and periodicals, read by
very few except specialists. Thus, few even of geo-
logical and biological students have clear ideas of the
real nature and mode of occurrence of these ancient
organisms, and of their relations to better known
forms of life ; while the crudest and most inaccurate
T^
4
THE DAWN OP LIFE.
ideas have been current in lectures and popular books,
and even in text-books, although to the minds of those
really acquainted with the facts, all the disputed points
have long ago been satisfactorily settled, and the true
nature and aflSnities of Eozoon are distinctly and
satisfactorily understood.
This state of things has long ceased to be desirable
in the interests of science, since the settlement of the
questions raised is in the highest degree important to
the history of life. We cannot, it is true, affirm that
Eozoon is in reality the long sought prototype of ani-
mal existence; but it is for us at present the last
organic foothold, on which we can poise ourselves, that
we may look back into the abyss of the infinite past,
and forward to the long and varied progress of life in
geological time. Its consideration, therefore, is cer-
tain, if properly entered into, to be fruitful of interest-
ing and valuable thought, and to form the best possible
introduction to the history of life in connection with
geology.
It is for these reasons, and because I have been
connected with this great discovery from the first, and
have for the last ten years given to it an amount of
labour and attention far greater than could be ade-
quately represented by short and technical papers,
that I have planned the present work. In it I propose
to give a popular, yet as far as possible accurate, ac-
count of all that is known of the Dawn-animal of the
Laurentian rocks of Canada. This will include, firstly:
a descriptive notice of the Laurentian formation itself.
INTRODUCTORY.
5
: books,
of those
d points
the true
itly and
lesirable
it of the
)rtant to
irm that
3 of ani-
the last
ves, that
lite past,
of life in
is cer-
interest-
possible
ion with
ive been
st, and
aount of
30 ade-
papers,
propose
ate, ac-
of the
firstly :
n itself.
iSecondly : a history of the steps which led to the
discovery and proper interpretation of this ancient
fossil. Thirdly : the description of Eozoon, and the
explanation of the manner in which its remains have
been preserved. Fourthly: inquiries as to forms of
animal life, its contemporaries and immediate succes-
sors, or allied to it by zoological affinity. Fifthly:
the objections which have been urged against its
organic nature. And sixthly : the summing up of the
lessons in science which it is fitted to teach. On these
points, while I shall endeavour to state the substance
of all that has been previously published, I shall bring
forward many new facts illustrative of points hitherto
more or less obscure, and shall endeavour so to picture
these in themselves and their relations, as to give
distinct and vivid impressions to the reader.
For the benefit of those who may not have access to
the original memoirs, or may not have time to consult
them, I shall append to the several chapters some of
the technical details. These may be omitted by the
general reader ; but will serve to make the work more
complete and useful as a book of reference.
The only preparation necessary for the unscientific
reader of this work, will be some little knowledge of
the division of geological time into successive ages,
as represc iited by the diagram of formations appended
to this chapter, and more full explanations may be
obtained by consulting any of the numerous element-
ary manuals on geology, or " The Story of the Earth
and Man," by the writer of the present work.
THE DAWN OP LIFE.
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11
CHAPTER II.
THE LAURENTIAN EOCKS.
As we descend in depth and time into tlie earth's
crust, after passing through nearly all the vast series
of strata constituting the monuments of geological
history, we at length reach the Eozoic or Laurentian
rocks, deepest and oldest of all the formations known
to the geologist, and more thoroughly altered or
metamorphosed by heat and heated moisture than any
others. These rocks, at one time known as Azoic,
being supposed destitute of all remains of living
things, but now more properly Eozoic, are those in
which the first bright streaks of the dawn of life make
their appearance."^
The name Laurentian, given originally to the
Canadian development of these rocks by Sir William
Logan, but now applied to them throughout the
world, is derived from a range of hills lying north
of the St. Lawrence valley, which the old French
geographers named the Laurentides. In these hills
the harder rocks of this old formation rise to consider-
able heights, and form the highlands separating the
* Dana has recently proposed the term " Archcean,*' on the
ground that some of these rocks are as yet unfossiliferous
but as the oldest known part of them contains fossils, there
tieems no need for this new name.
8
THE DAWN OP LIFE.
St. Lawrence valley from the great plain fronting on
Hudson's Bay and the Arctic Sea. At first sight it
may seem strange that rocks so aiicient should any-
where appear at the surface, especially on the tops of
hills ; but this is a necessary result of the mode of
formation of our continents. The most ancient
sediments deposited in the sea were those first
elevated into land, and first altered and hardened
by heat. Upheaved in the folding of the earth's
crust into high and rugged ridges, they have either
remained uncovered with newer sediments, or have
had such as were deposited on them washed away;
and being of a hard and resisting nature, they have
remained comparatively unworn when rocks much
more modern have been swept off by denuding
agencies.
But the exposure of the old Laurentian skeleton of
mother earth is not confined to the Laurentide Hills,
though these have given the formation its name. The
same ancient rocks appear in the Adirondack moun-
tains of New York, and in the patches which at
lower levels protrude from beneath the newer for-
mations along the American coast from Newfoundland
to Maryland. The older gneisses of Norway, Sweden,
and the Hebrides, of Bavaria and Bohemia, belong to
the same age, and it is not unlikely that similar rocks
iu many other parts of the old continent will be found
to be of as great antiquity. In no part of the world,
however, are the Laurentian rocks more extensively
distributed or better known than in North America ;
THE LAURENTIAN ROCKS.
and to this as the grandest and most
instructive development of them, and
that which first afforded organic re-
mains, we may more especially devote
our attention. Their general relations
to the other formations of America
may be learned from the rough gene-
ralised section (fig. 1) ; in which the
crumpled and contorted Laurentian
strata of Canada are seen to underlie
unconformably the comparatively flat
Silurian beds, which are themselves
among the oldest monuments of the
geological history of the earth.
The Laurentian rocks, associated
with another series only a little
younger, the Huronian, form a great
belt of broken and hilly country,
extending from Labrador across the
north of Canada to Lake Superior,
and thence bending northward to the
Arctic Sea. Everywhere on the lower
St. Lawrence they appear as ranges
of billowy rounded ridges on the
north side of the river ; and as viewed
from the water or the southern shore,
especially when sunset deepens their
tints to blue and violet, they present
a grand and massive appearance,
which, in the eye of the geologist.
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THE DAWN OP LIFE.
i
who knows that they have endured the battles and
the storms of time longer than any other mountains,
invests them with a dignity which their mere ele-
vation would fail to give. (Fig. 2.) In the isolated
mass of the Adirondacks, south of the Canadian
frontier^ they rise to a still greater elevation, and
form an imposing mountain group, almost equal in
height to their somewhat more modern rivals, the
White Mountains, which face them on the opposite
side of Lake Champlain.
The grandeur of the old Laurentian ranges is, how-
ever, best displayed where they have been cut across
by the great transverse gorge of the Saguenay, and
where the magnificent precipices, known as Capes
Trinity and Eternity, look down from their elevation
of 1500 feet on a fiord, which at their base is more
than 100 fathoms deep (see frontispiece). The name
Eternity applied to such a mass is geologically
scarcely a misnomer, for it dates back to the very
dawn of geological time, and is of hoar antiquity in
comparison with such upstart ranges as the Andes
and the Alps.
On a nearer acquaintance, the Laurentian country
appears as a broken and hilly upland and highland
district, clad in its pristine state with magnificent
forests, but affording few attractions to the agri-
culturist, except in the valleys, which follow the
lines of its softer beds, while it is a favourite region
for the angler, the hunter, and the lumberman*
Many of the Laurentian townships of Canada
TUE LAURENTIAN ROCKS.
11
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12
THE DAWN OF LIFE.
: I
i I
are, however, already extensively settled, and the
traveller may pass through a succession of more
or less cultivated valleys, bounded by rocks or
wooded hills and crags, and diversified by running
streams and romantic lakes and ponds, constituting
a country always picturesque and often beautiful,
and rearing a strong and hardy population. To the
geologist it presents in the main immensely thick
beds of gneiss, and similar metamorphic and crystal-
line rocks, contorted in the most remarkable manner,
so that if they could be flattened out they would serve
as a skin much too large for mother earth in her
present state, so much has she shrunk and wrinkled
since those youthful days when the Laurentian rocks
were her outer covering. (Fig. 3.)
The elaborate sections of Sir William Logan show
that these old rocks are divisible into two series, the
Lower and Upper Laurentian ; the latter being the
newer of the two, and perhaps separated from the
former by a long interval of time ; but this Upper
Laurentian being probably itself older than the
Huronian series, and this again older than all the
other stratified rocks. The Lower Laurentian, which
attains to a thickness of more than 20,000 feet, con-
sists of stratified granitic rocks or gneisses, of indu-
rated sandstone or quartzite, of mica and hornblende
schist, and of crystalline limestones or marbles, and
iron 6res, the whole interstratified with each other.
The Upper Laurentian, which is 10,000 feet thick at
least, consists in part of similar rocks, but associated
THE LAURENTIAN ROCKS.
13
with great beds of triclinio felspar,
especially of that peculiar variety
known as labradorite, or Labrador
felspar, and which sometimes by its
wonderful iridescent play of colours
becomes a beautiful ornamental
stone.
I cannot describe such rocks,
but their names will tell something
to those who have any knowledge
of the older crystalline materials
of the earth's crust. To those who
have not, I would advise a visit
to some cliff on the lower St. Law-
rence, or the Hebridean coasts, or
the shore of Norway, where the
old hard crystalline and gnarled
beds present their sharp edges to
the ever raging sea, and show their
endless alternations of various kinds
and colours of strata often diversi-
fied with veins and nests of crystal-
line minerals. He who has seen
and studied such a section of Lau-
rentian rock cannot forget it.
All the constituents of tho Lau-
rentian series are in that state
known to geologists as metamor-
phic. Tliey were once sandstones,
clays, and limestones, such as
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14
THE DAWN OF LIFE.
the sea now deposits, or such as form the common
plebeian rocks of everyday plains and hills and coast
sections. Being extremely old, however, they have
been buried deep in the bowels of the earth under
the newer deposits, and hardened by the action of
pressure and of heat and heated water. Whether
this heat was part of that originally belonging to the
earth when a molten mass, and still existing in its
interior after aqueous rocks had begun to form on its
surface, or whether it is a mere mechanical effect of
the intense compression which these rocks have
suffered, may be a disputed question ; but the ob-
servations of Sorby and of Hunt (the former in con-
nection with the microscopic structure of rocks, and
the latter in connection with the chemical conditions
of change) show that no very excessive amount of
heat would be required. These observations and those
of Daubree indicate that crystallization like that of
the Laurentian rocks might take place at a temperature
of not over 370" of the centigrade thermometer.
The study of those partial alterations which take
piace in the vicinity of volcanic and older aqueous
masses of rock confirms these conclusions, so that we
may be said to know the precise conditions under
which sediments may be hardened into crystalline
rocks, while the bedded character and the alterna-
tions of different layers in the Laurentian rocks, as
well as the indications of contemporary marine life
which they contain, show that they actually are such
altered sediments. (Seei Note D.)
THE LAUREMTIAN UOCKS.
15
It; is interesting to notice hero that the Laurontian
rocks thus interpreted show that the oldest known
portions of our continents were formed in the waters.
They are oceanic sediments deposited perhaps when
there was no dry land or very little, and that little
unknown to us except in so far as its debris may have
entered into the composition of the Laurentian rocks
themselves. Thus the earliest condition of the earth
known to the geologist is one in which old ocean
W0;S already dominant on its surface ; and any pre-
vious condition when the surface was heated, and the
water constituted an abyss of vapours enveloping its
surface, or any still earlier condition in which the
earth was gaseous or vaporous, is a matter of mere
inference, not of actual observation. The formless
and void chaos is a deduction of chemical and physical
principles, not a fact observed by the geologist. Still
we know, from the great dykes and masses of igneous
or molten rock which traverse the Laurentian beds,
that even at that early period there were deep-seated
fires beneath the crust; and it is quite possible that
volcanic agencies then manifested themselves, not only
with quite as great intensity, but also in the same
manner, as at subsequent times. It is thus not un-
likely that much of the land undergoing waste in
the earlier Laurentian time was of the same nature
with recent volcanic ejections, and that it formed
groups of islands in an otherwise boundless ocean.
However this may be, the distribution and extent
of these pre-Laurentian lands is, and probably ever
il
IG
THE DAWN OP LIFE.
must be, unknown to us ; for it was only after the
Laurentian rocks had been deposited, and after the
shrinkage of the earth's crust in subsequent times
had bent and contorted them, that the foundations
of the continents were laid. The rude oketch map
of America given in fig. 4 will show this, and will
also show that the old Laurentian mountains mark
out the future form of the American continent.
Fig. 4. The Laurcalian Nucletis of the American Continent.
Rocks so highly altered as the Laurentian beds can
scarcely be expected to hold well characterized fossil
remains, and those geologists who entertained any
hope that such remains might have been "oreserved.
'i|
THE LAUEENTIAN ROCKS.
17
long looked in vain for their actual discovery. Still,
as astronomers have suspected the existence of un-
known planets from observing perturbations not
accounted for, and as voyagers have suspected the
approach to unknown regions by the appearance of
floating wood or stray land birds, anticipations of such
discoveries have been entertained and expressed from
time to time. Lyell, Dana, and Sterry Hunt more es-
pecially, have committed themselves to such specula-
tions. The reasons assigned may bo stated thus : —
Assuming the Laurentian rocks to be altered sedi-
ments, they must, from their great extent, have been
deposited in the ocean; and if there had been no
living creatures in the waters, we have no reason to
believe that they would have consisted of anything
more than such sandy and muddy debris as may be
washed away from wasting rocks originally of igneous
origin. But the Laurentian beds contain other
materials than these. No formations of any geo-
logical age include thicker or more extensive lime-
stones. One of the beds measured by the officers of
the Geological Survey, is stated to be 1500 feet in
thickness, another is 1250 feet thick, and a third 750
feet; making an aggregate of 3500 feet.* These
beds may be traced, with more or less interruption,
for hundreds of miles. Whatever the origin of such
limestones, it is plain that they indicate causes equal
in extent, and comparable in power and duration,
with those which have produced the greatest lime-
* Logan : Geology of Canada, p. 45.
18
THE DAWN OF LIFE.
ilil
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I I '
Jilii
stones of the later geological periods. Now, in later
formations, limestone is usually an organic rock, accu-
mulated by the slow gathering frotn the sea-water, or
its plants, of calcareous matter, by corals, foraminifera,
or shell-fish, and the deposition of their skeletons,
either entire or in fragments, in the sea-bottora. Tho
most friable chalk and the most crystalline limestones
have alike been formed in this wnv. Wo know of no
reason why it should be different in the Laurentian
period. When, therefore, we find great and con-
formable beds of limestone, such as those described by
Sir William Logan in tho Laurentian of Canada, we
naturally imagine a quiet sea-bottom, in which multi-
tudes of animals of humble organization were accumu-
lating limestone in their hard parts, and depositing
this in gradually increasing thickness from age to age.
Any attempts to account otherwise for these thick and
greatly extended beds, regularly interstratified with
other deposits, have so far been failures, and have
arisen either from a want of comprehension of the
nature and magnitude of the appearances to be ex-
plained, or from the error of mistaking tho true
bedded limestones for veins of calcareous spar.
The Laurentian rocks contain great quantities of
carbon, in the form of graphite or plumbago. This
does not occur wholly, or even principally, in veins or
fissures, but in the substance of tho limestone and
gneiss, and in regular layers. So abundant is it, that
I have estimated the amount of carbon in one division
of the Lower Laurentian of tho Ottawa district at an
THE LAURENTIAN ROCKS.
11)
nggregato tliickncsa of not less thnn twenty to thirty
feet, an amount comparable with that in the true coal
formation itself. Now wo know of no agency existing
in present or in past geological time capable of
deoxidizing carbonic acid, and fixing its carbon as an
ingredient in permanent rocks, except vegetable life.
Unless, therefore, we suppose that there existed in the
Laurentian age a vast abundance of vegetation, either
in the sea or on the land, we have no means of
explaining the Laurentian graphite.
The Laurentian formation contains great beds of
oxide of iron, sometimes seventy feet in thickness.
Here again we have an evidence of organic action ; for
it is the deoxidizing power of vegetable matter which
has in all the later formations been the efficient cause
in producing bedded deposits of iron. This is the
case in modern bog and lake ores, in the clay iron-
stones of the coal measures, and apparently also in the
great ore beds of the Silurian rock May not similar
causes have been at work in the Le.^i'entian period ?
Any one of these reasons might, in itself, be held
insufficient to prove so great and, at first sight, un-
likely a conclusion as that of the existence of abundant
animal and vegetable life in the Laurentian ; but the
concurrence of the whole in a series ( ' deposits un-
questionably marine, forms a chain of evidence so
powerful that it might command belief even if no
fragment of any organic and living form or structure
had ever been recognised in these ancient rocks.
Such was the condition of the matter until the
^1
I
20
THE DAWN OP LIFE.
■■Mil ii>
iiiii
existence of supposed organic remains was announced
by Sir W. Logan, at the American Association for the
Advancement of Science, in Springfield, in 1 859 ; and
we may now proceed to narrate the manner of this
discovery, and how it has been followed up.
Before doing so, however, let us visit Eozoon in one
of its haunts among the Laurentian Hills. One of
the most noted repositories of its remains is the great
Grenville band of limestone (see section, fig. 3, and
map), the outcrop of which may be seen in our map of
the country near the Ottawa, twisting itself like a great
serpent in the midst of the gneissose rocks ; and one
of the most fruitful localities is at a place called
Cote St. Pierre on this band. Landing, as I did, with
Mr. Weston, of the Geological Survey, last autumn, at
Papineauville, we find ourselves on the Laurentian
rocks, and pass over one of the great bands of gneiss
for about twelve miles, to the village of St. Andre
Avelin. On the road we see on either hand abrupt
rocky ridges, partially clad with forest, and sometimes
showing on their flanks the stratification of the gneiss
in very distinct parallel bands, often contorted, as if
the rocks, when soft, had been wrung as a washer-
woman wrings clothes. Between the hills are little
irregular valleys, from which the wheat and oats have
just been reaped, and the tall Indian corn and yellow
pumpkins are still standing in the fields. Where not
cultivated, the land is covered with a rich second
growth of young maples, birches, and oaks, among
which still stand the stumps and tall scathed trunks of
'1
THE LAURENTIAN ROCKS.
21
enormous pines, which constituted the original forest.
Half way we cross the Nation River, a stream nearly
as large as the Tweed, flowing placidly between
wooded banks, which are mirrored in its surface ; but
in the distance we can hear the roar of its rapids,
dreaded by lumberers in their spring drivings of logs,
and which we were told swallowed up five poor fellows
only a few months ago. Arrived at St. Andre, we
find a wider valley, the indication of the change to the
limestone band, and along this, with the gneiss hills
still in view on either hand, and often encroaching on
the road, we drive for five miles more to Cote St.
Pierre. At this place the lowest depression of the
valley is occupied by a little pond, and, hard by, the
limestone, protected by a ridge of gneiss, rises in an
abrupt wooded bank by the roadside, and a little
further forms a bare white promontory, projecting into
the fields. Here was Mr. Lowe's original excavation,
whence some of the greater blocks containing Eozoon
were taken, and a larger opening made by an enter-
prising American on a vein of fibrous serpentine,
yielding '^rock v'^otton," for packing steam pistons
and similar purposes. (Figs. 5 and 6.)
The limestone is here highly inclined and much
contorted, and in all the excavations a thickness of
about 100 feet of it may be exposed. It is white and
crystalline, varying much however in coarseness in
different bands. It is in some layers pure and white,
in others it is traversed by many gray layers of
gneissose and other matter, or by irregular bands and
-m.
22
THE DAWN OF LIFE.
r7
,C// ////////
'''■'In! //''■■
/r/m,m/i''(X'////J/!!/;'
It-/-.
Fig. 5. Attitude of Limestone at St. Pierre.
(a.) Gneisa band in the Limestone, (b.) Limestone with Eozoon. (c.) Diorite
and Gneiss.
I!:
11
■s!l
Fio. 6. Gneiss and Limestone at St. Pierre.
(a ) Limestone, (b ) Gneiss and Diorite.
THE LACRENTIAN ROCKS.
23
nodules of pyroxene and serpentine, and it contains
subordinate beds of dolomite. In one layer only, and
tliis but a few feet tliick, does tlie Eozoon occur in any
abundance in a perfect state, thougb fragments and
imperfectly preserved specimens abound in other parts
of the bed. It is a great mistake to suppose that it
constitutes whole beds of rock in an uninterrupted
mass. Its true mode of occurrence is best seen on the
weathered surfaces of the rock, where the serpentinous
specimens project in irregular patches of various sizes,
sometimes twisted by the contortion of the beds, but
often too small to suffer in this way. On such
surfaces the projecting patches of the fossil exhibit
laminse of serpentine so precisely like the Stromatoporce
of the Silurian rocks, that any collector would pounce
upon them at once as fossils. In some places these
small weathered specimens can be easily chipped off
from the crumbling surface of the limestone ; and it is
perhaps to be regretted that they have not been more
extensively shown to palaeontologists, with the cut
slices which to many of them are so problematical.
One of the original specimens, brought from the
Calumet, and now in the Museum of the Geological
Survey of Canada, was of this kind, and much finer
specimens from Cote St. Pierre are now in that col-
lection and in my own. A very fine example is repre-
sented, on a reduced scale, in Plate III., which is taken
from an original photograph.* In some of the layers
are found other and more minute fossils than Eozoon,
* By Mr. Weston, of the Geological Survey of Canada.
' 4;!
;iiii|!
•i'';:l!
24
THE DAWN OF LIFE.
and these, togetlier with its fragmental remains, as
ingredients in the limestone, will bo discussed in the
sequel. We may merely notice here that the most
abundant layer of Eozoon at this place, occurs near
the base of the great limestone band, and that the
upper layers in so far as seen are less rich in it.
Further, there is no necessary connection between
Eozoon and the occurrence of serpentine, for there are
many layers full of bands and lenticular masses of
that mineral without any Eozoon except occasional
fragments, while the fossil is sometimes partially
mineralized with pyroxene, dolomite, or common lime-
stone. The section in fig. 5 will serve to show the
attitude of the limestone at this place, while the more
general section, fig. 3, taken from Sir William Logan,
shows its relation to the other Laurentian rocks, and
the sketch in fig. 6 shows its appearance as a feature
on the surface of the country.
NOTES TO CHAPTER II.
(A.) Sir William E. Logan on the Laukentian System.
[Journal of Geological Society of London, February, 1865. ]
After stating the division of the Laurentian series into the
two greftt groups of the Upper and Lower Laurentian, Sir
William goes on to say ; —
" The united thickness of these two groups in Canada can-
not be less than 30,000 feet, and probably much exceeds it.
The Laurentian of the west of Scotland, acording to Sir Rode-
rick Murchison, also attains a great thickness. In that region
the Upper Laurentian or Labrador series, has not yet been
THE LAURENTIAN ROCKS.
25
separately recognised ; but from Mr. McCulloch's description,
as well as from the specimens collected by him, and now in
the Museum of the Geological Society of London, it can
scarcely be doubted that the Labrador series occurs in Skye.
The labradorite and hypersthene rocks from that island are
identical with those of tho Labrador series in Canada and New
York, and unlike those of any formation at any other known
horizon. This resemblance did not escape the notice of Em-
mons, who, in his description of the Adirondack Mountains,
referred these rocks to the hypersthene rock of McCulloch,
although these observers, on the opposite sides of the Atlantic,
looked upon them as unstratified. In the Canadian Naturalist
for 1862, Mr, Thomas Macfarlane, for some time resident in
Norway, and now in Canada, drew attention to the striking
resemblance between the Norwegian primitive gneiss forma-
tion, as described by Naumann and Keilhau, and observed by
himself, and the Laurentian, including the Labrador group ;
and the equally remarkable similarity of the lower part of the
primitive slate formation to the Huronian series, which is a
third Canadian group. These primitive series attain a great
thickness in the north of Europe, and constitute the main
features of Scandinavian geology.
" In Bavaria and Bohemia there is an ancient gneissic series.
After the labours in Scotland, by which he was the first to
establish a Laurentian equivalent in the British Isles, Sir
Roderick Murchison, turning his attention to this central
European mass, placed it on the same horizon. These rocks,
underlying Barrande's Primordial zone, with a great develop-
ment of intervening clay-slate, extend southward in breadth
to the banks of the Danube, with a prevailing dip towards the
Silurian strata. They had previously been studied by Giimbcl
and Crejci, who divided them into an older reddish gneiss and
a newer grey gneiss. But, on the Danube, the mass which is
furthest removed from the Silurian rocks being a grey gneiss,
Giimbel and Crejci account for its presence by an inverted
fold in the strata ; while Sir Roderick places this at the base,
and regards the whole as a single series, in the normal funda-
mental position of the Laurentian of Scotland and of Canada.
26
THE DAWN OP LIFE.
Ill i
Considering the colossal thickness given to the series (90,000
feet), it remains to be seen whether it may not include both the
Lower and Upper Laurentian, and possibly, in addition, the
Huronian.
"This third Canadian group (the Huronian) has been shown
by my colleague, Mr. Murray, to be about 18,000 feet thick,
and to consist chiefly of quartzites, slate-conglomerates,
diorites, and limestones. The horizontal strata which form
the base of the Lower Silurian in western Canada, rest upon
the upturned edges of the Huronian series ; which, in its turn,
unconformably overlies the Lower Laurentian. The Huronian
is believed to be more recent than the Upper Laurentian series,
although the two formations have never yet been seen in con-
tact.
"The united thickness of these three great series may pos-
sibly far surpass that of all the succeeding rocks from the
base of the PalaDOzoic series to the present time. We are thus
carried back to a period so far remote, that the appearance of
the so-called Primordial fauna may by some be considered a
comparatively modern event. We, however, find that, even
during the Laurentian period, the same chemical and mechani-
cal processes which have ever since been at work disintegrat-
ing and reconstructing the earth's crust were in operation
as now. In the conglomerates of the Huronian series there
are enclosed boulders derived from the Laurentian, which seem
to show that the parent rock was altered to its present crystal-
line condition before the deposit of the newer formation;
while interstratified with the Laurentian limestones there are
beds of conglomerate, the pebbles of which are themselves
rolled fragments of a still older laminated sand-rock, and the
formation of these beds leads us still further into the past.
"In both the Upper and Lower Laurentian series there are
several zones of limestone, each of sufficient volume vto consti-
tute an independent formation. Of these calcareous masses
it has been ascertained that three, at least, belong to the
Lower Laurentian. But as we do not as yet know with cer-
tainty either the base or the summit of this series, these f^hree
may be conformably followed by many more. Although the
THE LAURENTIAN ROCKS.
27
Lower and Upper Laurentian rocks spread over more than
200,000 square miles in Canada, only about 1500 square miles
have yet been fully and connectedly examined in any one
district, and it is still impossible to say whether the numerous
exposures of Laurentian limestone met with in other parts of
the province are equivalent to any of the three zones, or
whether they overlie or underlie them all."
(B.) Br. Sterry Hunt on the PROBAUiiE Existence of
Life in the Laurentian Period.
Dr. Hunt's views on this subject were expressed in the
American Journal of Science, [2], vol. xxxi., p. 395. From this
article, written in 1861, after the announcement of the exist-
ence of laminated forms supposed to be organic in the Lauren-
tian, by Sir W. E. Logan, but before their structure and
affinities had been ascertained, I quote the following sen-
tences : —
" We see in the Laurentian series beds and veins of metallic
sulphurets, precisely as in more recent formations ; and the
extensive beds of iron ore, hundreds of feet thick, which
abound in that ancient system, correspond not only to great
volumes of strata deprived of that metal, but, as we may
suppose, to organic matters which, but for the then great
diffusion of iron-oxyd in conditions favourable for their oxi-
dation, might have formed deposits of mineral carbon far
more extensive than those beds of plumbago which we actually
meet in the Laurentian strata. All these conditions lead us
then to conclude the existence of an abundant vegetation
during the Laurentian period.
it
' ,,.
(C.) The GRArniTE of the Laurentian.
The following is from a paper by the author, in the Journal
of the Geologichl Society, for February, 1870: —
" The graphite of the Laurentian of Canada occurs both in
beds and in veins, and in such a manner as to show that its
origin and deposition are contemporaneous with those of tha
28
THE DAWN OF LIFE.
I liii i
i
liljl l,!il
containing rock. Sir William Logan states* that 'the de-
posits of plumbago generally occur in the limestones or in
their immediate vicinity, and granular varieties of the rock
often contain large crystalline plates of plumbago. At other
times this mineral is so finely disseminated as to give a bluish-
gray colour to the limestone, and the distribution of bands
thus coloured, seems to mark the stratification of the rock.'
He further states: — 'The plumbago is not confined to the
limestones ; large crystalline scales of it are occasionally dis-
seminated in pyroxene rock or pyrallolite, and sometimes in
quartzite and in feldspathic rocks, or even in magnetic oxide
of iron.' In addition to these bedded forms, there are also
true veins in which graphite occurs associated with calcite,
quartz, orthoclase, or pyroxene, and either in disseminated
scales, in detached masses, or in bands or layers 'separated
from each other and from the wall rock by feldspar, pyroxene,
and quartz.' Dr. Hunt also mentions the occurrence of finely
granular varieties, and of that peculiarly waved and corru-
gated variety simulating fossil wood, though really a mere form
of laminated structure, which also occurs at Warrensburgh,
New York, and at the Marinski mine in Siberia. Many of the
veins are not true fissures, but rather constitute a network of
shrinkage cracks or segregation veins traversing in countless
numbers the containing rock, and most irregular in their
dimensions, so that they often resemble strings of nodular
masses. It has been supposed that the graphite of the veins
was originally introduced as a liquid hydrocarbon. Dr. Hunt,
however, regards it as possible that it may have been in a
state of aqueous solution ; f but in whatever way introduced,
the character of the veins indicates that in the case of the
greater number of them the carbonaceous material must have
been derived from the bedded rocks traversed by these veins,
while there can be no doubt that the graphite found in the
beds has been deposited along with the calcareous matter or
muddy and sandy sediment of which these beds were originally
composed.
* Geology of Canada, 1863.
t Report of the Geological Survey of Canada, 18G6.
THE LAURE?JTIAN ROCKS.
29
; ■ I.,
i
" The quantity of graphite in the Lower Laurentian series ia
enormous. In a recent visit to the township of Buckingham,
on the Ottawa River, I examined a band of limestone believed
to be a continuation of that described by Sir W. E. Logan as
the Green Lake Limestone. It was estimated to amount, with
some thin interstratified bands of gneiss, to a thickness of 600
feet or more, and was found to be filled with disseminated
crystals of graphite and veins of the mineral to such an ex-
tent as to constitute in some places one-fourth of the whole ;
and making every allowance for the poorer portions, this band
cannot contain in all a less vertical thickness of pure graphite
than from twenty to thirty feet. In the adjoining township of
Lochaber Sir W. E. Logan notices a band from twenty-five to
thirty feet thick, reticulated with graphite veins to such an
extent as to be mined with profit for the mineral. At another
place in the same district a bed of graphite from ten to twelve
feet thick, and yielding twenty per cent, of the pure material, is
worked. "^Yhen it is considered that graphite occurs in similar
I'.bundance at several other horizons, in beds of limestone
which aave been ascertained by Sir W. E. Logan to have an
aggregate thickness of 3500 feet, it is scarcely an exaggeration
to maintain that the quantity of carbon in the Laurentian is
equal to that in similar areas of the Carboniferous system. It
is also to be observed that an immense area in Canada appears
to be occupied by these graphitic and Eozoon limestones, and
that rich graphitic deposits exist in the continuation of this
system in the State of New York, while in rocks believed to
be of this age near St. John, New Brunswick, there is a very
thick bed of graphitic limestone, and associated with it three
regular beds of graphite, having an aggregate thickness of
about five feet.*
" It may fairly be assumed that in the present world and in
those geological periods with whose organic remains we are
more familiar than with those of the Laurentian, there is no
other source of unoxidized carbon in rocks than that furnished
by organic matter, and that this has obtained its carbon in all
* Matthew, in Quart. Journ. GeoL Soc, vol. xxi., p. 423. Acadian
Geology, p. C62.
' ■
.J,
*^^
30
THE DAWN OP LIFE.
h i
mIiIi,
III
tllll!|j:,:,::
jijlMiiijv!
cases, in the first instance, from the dooxidation of carbonic
acid by living plants. No other source of carbon can, I
believe, bo imagined in the Laurentian period. We may, how-
ever, suppose either that the graphitic matter of the Lauren-
tian has been accumulated in beds like those of coal, or that
it has consisted of diffused bituminous matter similar to that
in more modern bituminous shales and bituminous and oil-
bearing limf^stones. The beds of graphite near St. John,
some of those in the gneiss at Ticonderoga in New York, and
at Lochaber and Buckingham and elsewhere in Canada, are so
pure and regular that one might fairly compare ihem with the
graphitic coal of Ehode Island. These instances, however,
are exceptional, and the greater part of the disseminated and
vein graphite might rather be compared in its mode of occur-
rence to the bituminous matter in bituminous shales and
limestones.
** We may compare the disseminated graphite to that which
we find in those districts of Canada in which Silurian and
Devonian bituminous shales and limestones have been meta-
morphosed and converted into graphitic rocks not dissimilar
to those in the less altered portions of the Laurentian.* In
like manner it seems probable that the numerous reticulating
veins of graphite may have been formed by the segregation
of bituminous matter into fissures and planes of least resist-
ance, in the manner in which such veins occur in modern
bituminous limestones and shales. Such bituminous veins
occur in the Lower Carboniferous limestone and shale of Dor-
chester and Hillsborough, New Brunswick, with an arrange-
ment very similar to that of the veins of graphite ; and in the
Quebec rocks of Point Levi, veins attaining to a thickness of
more than a foot, are filled with a coaly matter having a trans-
verse columnar structure, and regarded by Logan and Hunt
as an altered bitumen. These palaeozoic analogies would lead
us to infer that ^lie larger part of the Laurentian graphite falls
under the second class of deposits above mentioned, and that,
if of vegetable origin, the organic matter must have been
*Granby, Melbourne, Owl's Head, etc., Geology of Canada, 1863,
r. 599.
THE LAURENTIAN ROCKS.
31
thoroiiglily di.sintogratod and bitiiminized before it waa
changed into graphite. This would also give a probability
that the vegetation implied was aquatic, or at least that it
was accumulated under water.
" Dr. Hunt has, however, observed an indication of terres-
trial vegetation, or at least of subaiirial decay, in the great
beds of Laurentian iron ore. Those, if formed in the same
manner as more modern deposits of this kind, would imply the
reducing and solvent action of substances produced in the
decay of plants. In this case such great ore beds as that of
Hull, on the Ottawa, seventy feet thick, or that near New-
borough, 200 feet thick,* must represent a corresponding
quantity of vegetable matter which has totally disappeared.
It may be added that similar demands on vegetable matter as
a deoxidizing agent are made by the beds and veins of metallic
sulphides of the Laurentian, though some of the latter are no
doubt of later date than the Laurentian rocks themselves.
"It would be very desirable to confirm such conclusions as
those above deduced by the evidence of actual microscopic
structure. It is to be observed, however, that when, in more
modern sediments, algae have been converted into bituminous
matter, we cannot ordinarily obtain any structural evidence of
the origin of such bitumen, and in the graphitic slates and
limestones derived from the metamorphosis of such rocks no
organic structure remains. It is true that, in certain bitumin-
ous shales and limestones of the Silurian system, shreds of
organic tissue can sometimes be detected, and in some cases,
as in the Lower Silurian limestone of the La Cloche mountains
in Canada, the pores of brachiopodous shells and the cells of
corals have been penetrated by black bituminous matter,
f( rming what may be regarded as natural injections, some-
times of much beauty. In correspondence with this, while in
some Laurentian graphitic rocks, as, for instance, in the com-
pact graphite of Clarendon, the carbon presents a curdled
appearance due to segregation, and precisely similar to that of
the bitumen in more modern bituminous rocks, I can detect
in the graphitic limestones occasional fibrous structures which
* Geology of Canada, 18G3.
> ,.:
82
THE DAWN OP LIFE.
,ii:i^
i!;|i:r
may bo remains of plants, and in some specimens vermicular
lines, which I believe to bo tubes of Eozoon penetrated by
matter once bituminous, but now in the state of graphite.
" When palaeozoic land-plants have been converted into
jrraphite, they sometimes perfectly retain their structure,
eral charcoal, with structure, exists in the graphitic coal
- Rhode Island. The fronds of ferns, with their minutest
veins perfect, are preserved in tho Devonian shales of St.
John, in the state of graphite; and in the same formation
there are trunks of Conifers {Dadoxylon ouangondianum) in
which the material of the cell-walls has been converted into
graphite, while their cavities have been filled with calcareous
spar and quartz, the finest structures being preserved quite as
well as in comparatively unaltered specimens from the coal-
formation.* No structures so perfect have as yet been de-
tected in the Laurentian, though in the largest of the three
'^raphitic beds at St. John there appear to be fibrous struc-
•ea which I believe may indicate the existence of land-
.ts. This graphite is composed of contorted and slicken-
sided laminas, much like those of some bituminous shales and
coarse coals ; and in these there are occasional small pyritous
masses which show hollow carbonaceous fibres, in some cases
presenting obscure indications of lateral pores. I regard
these indications, however, as uncertain; and it is not as yet
fully ascertained that these beds at St. John are on the same
geological horizon with the Lower Laurentian of Canada,
though they certainly underlie the Primordial series of the
Acadian group, and are separated from it by beds having the
character of the Huronian.
" There is thus no absolute impossibility that distinct
organic tissues may be found in the Laurentian graphite, if
formed from land-plants, more especially if any plants existed
at that time having true woody or vascular tissues ; but it
cannot with certainty be affirmed that such tissues have
been found. It is possible, however, that in the Laurentian
period the vegetation of the land may have consisted wholly
* Acadian Geology, p. 536. In calcified specimens the structures
remain in the graphite after decalcification by an acid.
THE LAURENTIAN ROCKS.
33
of cellular plants, as, for example, mosses and lichons ; and if
so, there would bo comparatively little hope of the distinct
preservation of their forms or tissues, or of our being able
to distinguish the remains of land-plants from those of Alga).
"We may sum up those facts and considerations in the
following statements : — First, that somewhat obscure traces of
organic structure can be detected in the Laurentian graphite ;
secondly, that the general arrangement and microscopic struc-
ture of the substance corresponds with that of the carbon-
aceous and bituminous matters in marine formations of more
modern date; thirdly, that if the Laurentian graphite has
been derived from vegetable matter, ic has only undergone a
metamorphosis similar in kind to that which organic matter
in metamorphosed sediment of later age has experienced;
fourthly, that the association of the graphitic matter with
organic limestone, beds of iron ore, and metallic sulphides,
greatly strengthens the probability of its vegetable origin;
fifthly, that when we consider the immense thickness and
extent of the Eozoonal and graphitic limestones and iron ore
deposits of the Laurentian, if we admit the organic origin of
the limestone and graphite, we m'ldt be prepared to believe
that the life of that early period, though it may have ex-
isted under low forms, was most copiously developed, and
that it equalled, perhaps surpassed, in its results, in the way
of geological accumulation, that of any subsequent period."
(D.) Western and other Laurentian Rocks, etc.
In the map of the Laurentian nucleus of America (fig. 4,)
I have not inserted the Laurentian rocks believed to exist in
the Rocky Mountains and other western ranges. Their dis-
tribution is at present uncertain, as well as the date of their
elevation. They may indicate an old line of Laurentian
fracture or wrinkling, parallel to the west coast, and defining
its direction. In the map there should be a patch of Lauren-
tian in the north of Newfoundland, and it should be wider at
the west end of lake Superior.
Full details as to the Laurentian rocks of Canada and sec-
D
i
34
THE DAWN OF LIFE.
II I
:;|i|!|:
tional lists o£ their beds will be found in the Reports of the
Geological Survey, and Dr. Hunt has discussed very fully
their chemical characters and metamorphism in his Chemical
and Geological Essays. The recent reports of Hitchcock on
New Hampshire, and Hayden on the Western Territories,
contain some new facts of interest. The former recognises
in the White Mountain region a series of gneisses and other
altered rocks of Lower Laurentian age, and, resting uncon-
formably on these, others corresponding to the Upper Lau-
rentian ; while above the latter are other pre-silurian formations
corresponding to the Huronian and probably to the Montalban
series of Hunt. These facts confirm Logan's results in Canada ;
and Hitchcock finds many reasons to believe in the existence
of life at the time of the deposition of these old rocks.
Eayden's report describes granitic and gneissose rocks, pro-
bably of Laurentian age, as appearing over great areas in
Colorado, Arizona, Utah, and Nevada — showing the existence
of this old metamorphic floor over vast regions of Western
America.
The metamorphism of these rocks does not imply any
change of their constituent elements, or interference with
their bedded arrangement. It consists in the alteration of the
sediments by merely molecular changes re-arranging their par-
ticles so as to render them crystalline, or by chemical reactions
producing new combinations of their elements. Experiment
shows that the action of heat, pressure, and waters containing
alkaline carbonates and silicates, would produce such changes.
The amount and character of change would depend on the
composition of the sediment, the heat applied, the subLtances
in solution in the water, and the lapse of time. (See Hunt's
Essays, p. 24.)
1':! iul:i
i "ji
l\
.a.
* ■
if
p-1
Oi H
N ?
lo
CHAPTER III.
THE HISTORY OF A DISCOVERY.
^1^
It is a trite remark that most discoveries are made, not
by one person, but by tlie joint exertions of many, and
that they have their preparations made often long be-
fore they actually appear. In this case the stable
foundations were laid, years before the discovery of
Eozoon, by the careful surveys made by Sir William
Logan and his assistants, and the chemical examina-
tion of the rocks and minerals by Dr. Sterry Hunt.
On the other hand. Dr. Carpenter and others in Eng-
land were examining the structure of the shells of the
humbler inhabitants of the modern ocean, and the
manner in which the pores of their skeletons become
infiltrated with mineral matter when deposited in the
sea-bottom. These laborious and apparently dissimi-
lar branches of scientific inquiry were destined to be
united by a series of happy discoveries, made not for-
tuitously but by painstaking and intelligent observers.
The discovery of the most ancient fossil was thus not
the chance picking up of a rare and curious specimen.
It was not likely to be found in this way; and if so
found, it would have remained unnoticed and of no
scientific value, but for the accumulated stores of zoo-
I: 11
i ilil
lilllli
«l!'i
36
THE DAWN OP LTFK.
logical and palseontological knowledge, and the sur-
veys previously made, whereby the age and distribution
of the Laurentian rocks and the chemical conditions
of their deposition and metamorphisra were ascer-
tained.
The first specimens of Eozoon ever jDrocured, in so
far as known, were collected at Burgess in Ontario
by a veteran Canadian mineralogist, Dr. Wilson of
Perth, and were sent to Sir William Logan as mineral
specimens. Their chief interest at that time lay in
the fact that certain lamina) of a dark green mineral
Fio. 7. Eozoon mineralized by Loganitc and Dolomite.
(Collected by Dr. Wilson, of Perth.)
present in the specimens were found, on analysis by
Dr. Hunt, to be composed of a new hydrous silicate,
allied to serpentine, and which he named loganite : one
of these specimens is represented in fig. 7. The form of
this mineral was not suspected to be of organic origin.
Some years after, in 1858, other specimens, differently
mineralized with the minerals serpentine and pyrox-
TUE HISTORY OF A DJSCOVKllY.
37
ene, were found by Mr. J. McMullen, an explorer in
the service of the Geological Survey, in the limestone
of the Grand Calumet on the River Ottawa. These
seem to have at once struck Sir W. E. Logan as re-
sembliug the Silurian fossils known as Stromatojpora ,
and he showed them to Mr. Billings, the palaeontolo-
gist of the survey, and to the writer, with this sugges-
tion, confirming it with the sagacious consideration
that inasmuch as the Ottawa and Burgess specimens
were mineralized by different substances, yet were
alike in form, there was little probability that they
were merely mineral or concretionary. Mr. Billings
was naturally unwilling to risk his reputation in affirm-
ing the organic nature of such specimens; and my own
suggestion was that they should be sliced, and ex-
amined microscopically, and that if fossils, as they
presented merely concentric laminae and no cells, they
would probably prove to be protozoa rather than
corals. A few' slices were accordingly made, but no
definite structure could be detected. Nevertheless
Sir William Logan took some of the specimens to the
meeting of the American Association at Springfield,
in 1859, and exhibited them as possibly Laurentian
fossils ; but the announcement was evidently received
with some incredulity. In 1862 they were exhibited
by Sir William to some geological friends in London,
but he remarks that " few seemed disposed to believe
iu their organic character, with the exception of my
friend Professor Ramsay." In 1863 the General Re-
port of the Geological Survey, summing up its work
38
THE DAWN OP LIFE.
to that timOj was published, under the name of the
Geology of Canada, and in this, at page 49, will be
found two figures of one of the Calumet specimens,
here reproduced, and which, though unaccompanied
with any specific name or technical description, were
referred to as probably Laurentian fossils. (Figs. 8
and 9.)
About this time Dr. Hunt happened to mention to
me, in connection with a paper on the mineralization of
fossils which he was preparing, that he proposed to
notice the mode of preservation of certain fossil woods
and other things with which I was familiar, and that
he would show me the paper in proof, in order that
he might have any suggestions that occurred to me.
On reading it, I observed, among other things, that
he alluded to the supposed Laurentian fossils, under
the impre«sion that the organic part was represented
by the serpentine or loganite, and that the calcareous
matter was the filling of the chambers. I took ex-
ception to this, stating that though in the slices before
examined no structure was apparent, still my impres-
sion was that the calcareous matter was the fossil, and
the serpentine or loganite the filling. He said — " In
that case, would it not be well to re-examine the speci-
mens, and to try to discover which view is correct ? "
He mentioned at the same time that Sir William had
recently shown him some new and beautiful specimens
collected by Mr. Lowe, one of the explorers on the
staff of the Survey, from a third locality, at Grenville,
on the Ottawa. It was supposed that these might
THE HISTORY OP A DISCOVERY.
39
Fig. 8. Weathered Specimen of Eozoon from the Calumet.
(Collected by Mr. McMullen.)
I' (
M
11
I
Fig. 9. Cross Section of the Specimen represented in Fig. 8.
The dark parts are the laminae of calcareous matter converging to the outer
« surface.
t 'j'
40
THE DAWN OP LIFE.
i!
throw further light on the subject; and accordingly
Dr. Hunt suggested to Sir William to have additional
slices of these new specimens made by Mr. Weston, of
the Survey, whose skill as a preparer of these and
other fossils has often done good service to science.
A few days thereafter, some slices were sent to me,
and were at once put under the microscope. I was
delighted to find in one of the first specimens examined
a beautiful group of tubuli penetrating one of the
calcite layers. Here was evidence, not only that the
calcite layers represented the true skeleton of the
fossil, but also of its affinities with the Foraminifera,
whose tubulated supplemental skeleton, as described
and figured by Dr. Carpenter, and represented in speci-
mens in my collection presented by him, was evidently
of the same type with that preserved in the canals of
these ancient fossils. Fig. 10 is an accurate represen-
tation of the first seen group of canals penetrated by
serpentine.
On showing the structures discovered to Sir William
Logan, he entered into the matter with enthusiasm,
and had a great number of slices and afterwards of
decalcified specimens prepared, which were placed in
my hands for examination.
Feeling that the discovery was most important, but
that it would be met with determined scepticism by a
great many geologists, I was not content with examin-
ing the typical specimens of Eozoon, but had slices
prepared of every variety of Laurentian limestone, of
altered limestones from the Primordial and Silurian,
"•»?! :;
THE HISTORY OF A DISCOVERY.
41
and of serpentine marbles of all the varieties famished
by our collections. These were examined with ordi-
nary and polarized light, and with every variety of
illumination. Dr. Hunt, on his part, undertook the
chemical investigation of the various associated
minerals. An extensive series of notes and camera
tracings were made of all the appearances observed ;
Fig. 10. Group of Canals in the Supplemental Skeleton of Eozoon.
Taken from the specimen in which they were first recognised. Magnified.
and of some of the more important structures beauti-
ful drawings were executed by the late Mr. H. S.
Smith, the then paloBontological draughtsman of
the Survey. The result of the whole investigation
was a firm conviction that the structure was organic
and foraminiferal, and that it could be distinguished
from any merely mineral or crystalline forms occu]--
ring in these or other limestones.
42
THE DAWN OP LIFE.
At this stage of tlie matter, and after exhibiting to
Sir William all the characteristic appearances in com-
parison with such concretionary, dendritic, and crystal-
lino structures as most resembled them, and also with
the structure of recent and fossil Foraminifera, 1
suggested that the further prosecution of the matter
should be handed over to Mr. Billings, as palajontolo-
gist of the Survey, and as our highest authority on
the fjssils of the older rocks. I was engaged in other
researches, and knew that no little labour must be
devoted to the work and to its publication, and that
some controversy might be expected. Mr. Billings,
however, with his characteristic caution and modesty,
declined. His hands, he said, were full of other work,
and he had not specially studied the microscopic ap-
pearances of Foraminifera or of mineral substances.
It was finally arranged that I should prepare a de-
scription of the fossil, which Sir William would take to
London, along with Dr. Hunt's notes, the more im-
portant specimens, and lists of the structures observed
in each. Sir William was to submit the manuscript
and specimens to Dr. Carpenter, or failing him to
Prof. T. Rupert Jones, in the hope that these eminent
authorities would confirm our conclusions, and bring
forward new facts which I might have overlooked or
been ignorant of. Sir William saw both gentlemen,
who gave their testimony in favour of the organic and
foraminiferal character of the specimens ; and Dr.
Carpenter in particular gave much attention to the
subject, and worked out the structure of the primary
THE HISTORY OF A DISCOVERY.
43
cell-wall, which I had not observed previously through
a curious accident as to specimens.* Mr. Lowe had
been sent back to the Ottawa to explore, and just bo-
fore Sir William^s departure had sent in some speci-
mens from a new locality at Petito Nation, similar in
general appearance to those from Grenville, which Sir
*>
i
w^^mmii
, ^w^y_ -^
Fig. 11. Portion of Eozoon magnified 100 diameters, shelving the
original Cell-tvall with Tubulation, and the Supplemental Skeleton
xoith Canals, {After Carpenter.)
(a.) Original tubulate'l wall or " Nuramuline layer," more magnified in fig. 2.
(b, c.) " Intermediate skeleton," with canals.
William took with him unsliced to England. These
showed in a perfect manner the tubuli of the primary
cell-wall, which I had in vain tried to resolve in the
* In papers by Dr. Carpenter, subsequently referred to.
Prof. Jor.od published an able exposition of the facts in the
Popular Science Monthly.
44
THE DAWN OP LIFE.
Grenville specimeua, and wLicli 1 did not see until
after it had been detected by Dr. Carpenter in Lon-
don. Dr. Carpenter thus contributed in a very im-
portant manner to the perfecting of the investigations
begun in Canada, and on him has fallen the greater
part of their illustration and defence,* in so far as Great
Britain is concerned. Fig. 11, taken from one of Dr.
Carpenter's papers, shows the tubulated primitive wall
as described by him.
The immediate result was a composite paper in the
rroceedhigs of the Geological Society, by Sir W. E.
Logan, Dr. Carpenter, Dr. Hunt, and myself, in which
the geology, palaeontology, and mineralogy of Eozoon
Canadense and its containing rocks were first given to
the world.f It cannot be wondered at that when
geologists and pala3ontologists were thus required to
believe in the existence of organic remains in rocks
regarded as altogether Azoic and hopelessly barren of
fossils, and to carry back the dawn of life as far before
those Primordial rocks, which were supposed to con-
tain its first traces, as these are before the middle
period of the earth's life history, some hesitation should
be felt. Further, the accurate appreciation of the
evidence for such a fossil as Eozoon required an
amount of knowledge of minerals, of the more humble
* In Quarterly Journal of Geological Society, vol. xxii. ; Froc.
Royal Society, vol. xv. ; Intellectual Observer, 1865. Annals
and Magazine of Natural History, 1874 ; and other papers and
notices.
f Journal Geological Society, February, 1865.
THE HISTORY OP A DISCOVEUY.
45
types of animals, and of tlio conditions of mineraliza-
tion of organic remains, possessed by few even of pro-
fessional geologists. Thus Eozoon has met with some
negative scepticism and a little positive opposition, —
though the latter has been small in amount, when wo
consider the novel and startling character of the facts
adduced.
" The united thickness,'' says Sir William Logan,
" of these three great series, the Lower and Upper
Laurentian and Iluronian, may possibly far surpass
that of all succeeding rocks, from the base of the Palaeo-
zoic to the present time. We are thus carried back
to a period so far remote that the appearance of the
so-called Primordial fauna may be considered a com-
paratively modern event." So great a revolution of
thought, and this based on one fossil, of a character
little recognisable by geologists generally, might well
tax the faith of a class of men usually regarded as
somewhat faithless and sceptical. Yet this new exten-
sion of life has been generally received, and has found
its way into text-books and popular treatises. Its
opponents have been under the necessity of inventing
the most strange and incredible pseudomorphoses
of mineral substances to account for the facts; and
evidently hold out rather in the spirit of adhesion to
a lost cause than with any hope of ultimate success.
As might have been expected, after the publication of
the original paper, other facts developed themselves.
Mr. Vennor found other and scarcely altered speci-
mens in the Upper Laurentian or Huronian of Tudor.
il I'p!
I
lillill
4G
THE DAWN OF LIFE.
Gumbel recognised tlie organism in Laurentian Rocks
in Bavaria and elsewhere in Europe, and discovered a
new species in the Huronian of Bavaria.^ Eozoon
was recognised in Laurentian hmestones in Massa-
chusetts t and New York, and there has been a rapid
growth of new facts increasing our knowledge of Fora-
minifera of similar types in the succeeding Pala)ozoic
rocks. Special interest attaches to the discovery by
Mr. Vennor of specimens of Eozoon contained in a
dark micaceous limestone at Tudor, in Ontario, and
really as little metam.orphosed as many Silurian fossils.
Though in this state they show their minute structures
less perfectly than in the serpentine specimens, the
fact is most important with reference to the vindica-
tion of the animal nature of Eozoon. Another fact
whose significance is not to be over-estimated, is the
recognition both by Dr. Carpenter and myself of speci-
mens in which the canals are occupied by calcite like
that of the organism itself. Quite recently I have, as
mentioned in the last chapter, been enabled to re-ex-
amine the locality at Petite Nation originally disco-
vered by Mr. Lowe, and am prepared to show that all
the facts with reference to the mode of occurrence of
* Ueher das Vorhommeyi von Eozoon, 1866.
f By Mr. Bicknell at Newbury, and Mr. Burbank at Cliehns-
ford. The latter gentloman has since maintained that the
limestones at the latter place are not true beds; but his own
descriptions and figures, lead to the belief that this is an
error of observation on his part. The Eozoon in the Chelms-
ford specimens and in those of "Warren, New York, is in small
and rare fragments in serpentinous limestone.
THE HISTORY OF A DISCOVERY.
47
the forms in the beds, and their association with layers
of fragmental Eozoon, are strictly in accordance with
the theory that these old Laurentian limestones are
truly marine deposits, holding the remains of the sea
animals of their time.
Eozoon is not, however, the only witness to the
great fact of Laurentian life, of which it is the most
conspicuous exponent. In many of the Laurentian
limestones, mixed with innumerable fragments of
Eozoon, there are other fragments with traces of
organic structure of a different character. There are
also casts in silicious matter which seem to indicate
smaller species of Foraminifera. There are besides
to be summoned in evidence the enormous accumula-
tions of carbon already referred to as existing in the
Laurentian rocks, and the worm-burrows, of which
very perfect traces exist in rocks probably of Upper
Eozoic age.
Other discoveries also are foreshadowed here. The
microscope may yet detect the true nature and affi-
nities of some of the fragments associated with Eozoon.
Less altered portions of the Laurentian rocks may be
found, where even the vegetable matter may retain its
organic forms, and where fossils may be recognised by
their external outlines as well as by their internal
structure. The Upper Laurentian and the Huronian
have yet to yield up their stores of life. Thus the
time may come when the rocks now called Primordial
shall not be held to be so in any strict sense, and when
swarming dynasties of Protozoa and other low forms
•<^^H
'i iillBJ, jM
11
I
m
lil!
iiiil
48
THE DAWN OF LIFE.
of life may be known as inhabitants of oceans vastly
ancient as compared with even the old Primordial
seas. Who knows whether even the land of the Lau-
rentian time may not have' been clothed with plants,
perhaps as much more strange and weird than those
of the Devonian and Carboniferous, as those of the lat-
ter are when compared with modern forests ?
(A.)
NOTES TO CHAPTER III.
Sm William E. Logan on the Discovery and
Characters of Eozoon.
[Journal of Geological Society, February, 1865.]
" III the examination of these ancient rocks, the question
has often naturally occurred to me, whether during these
remote periods, life had yet appeared on the earth. The
apparent absence of fossils from the highly crystalline lime-
stones did not seem to offer a proof in the negative, any more
than their undiscovered presence in newer crystalline lime-
stones where we have little doubt they have been obliterated
by metamorphic action ; while the carbon which, in the form
of graphite, constitutes beds, or is disseminated through the
calcareous or siliceous strata of the Laurentian series, seems
to be an evidence of the existence of vegetation, since no one
disputes the organic character of this mineral in more recent
rocks. My colleague, Dr. T. Sterry Hunt, has argued for the
existence of organic matters at the earth's surface during the
Laurentian period from the presence of great beds of iron ore,
and from the occurrence of metallic sulphurets ; * and finally,
the evidence was strengthened by the discovery of supposed
organic forms. These were first brought to me, in October,
1 858, by Mr. J. McMuUen, then attached as an explorer to the
* Quarterly Journal of the Geological Society, xv., 493.
Augus
M II
THE HISTORY OF A DISCOVERY.
49
Geological Survey of the province, from one of the limestones
of the Laurentian series occurring at the Grand Calumet, on
the river Ottawa.
" Any organic remains which may have been entombed in
these limestones would, if they retained their calcareous cha-
racter, be almost certainly obliterated by crystallization ; and
it would only be by the replacement of the original carbonate
of lime by a different mineral substance, or by an infiltration
of such a substance into all the pores and spaces in and about
the fossil, that its form would be preserved. The specimens
from the Grand Calumet present parallel or apparently concen-
tric layers resembling those of Stromatopora, except that they
anastomose at various points. What were first considered the
layers are composed of crystallized pyroxene, while the then
supposed interstices consist of carbonate of lime. These
specimens, one of which ia figured in Geology of Canada,
p. 49, called to memory others which had some years previously
been obtained from Dr. James Wilson, of Perth, and were then
regarded merely as minerals. They came, I believe, from
masses in Burgess, but whether in place is not quite certain;
and they exhibit similar forms to those of the Grand Calumet,
composed of layers of a dark green magnesian silicate
(loganite) ; while what were taken for the interstices are ailed
with crystalline dolomite. If the specimens from both these
places were to be regarded as the result of unaided mineral
arrangement, it appeared to me strange that identical forms
should be derived from minerals of such different composition.
I was therefore disposed to look upon them as fossils, and as
such they were exhibited by me at the meeting of the American
Association for the Advancement of Science, at Springfield, in
August, 1859. See Canadian Naturalist, 1859, iv., 300. In
18G2 they were shown to some of my geological friends in
Great Britain ; but no microscopic structure having been
observed belonging to them, few seemed disposed to believe
in their organic character, with thj exception of my friend
Professor Eamsay.
" One of the specimens had been sliced and submitted to
microscopic observation, but unfortunately it was one of those
E
1
50
THE DAWN Of LIFE.
III
ilii'
III II ii
II III l'<'t
III
hli'i
i
i!:
composed of loganite and dolomite. In these, the minute
structure is rarely seen. The true character of the specimens
thus remained in suspense until last winter, when I accident-
ally observed indications of similar forms in blocks of Lauren-
tian limestone which had been brought to our museum by Mr.
James Lowe, one of our explorers, to be sawn up for marble.
In this case the forms were composed of serpentine and calc-
spar; and slices of them having been prepared lor the micro-
scope, the minute structure was observed in the first one
submitted to inspection. At the request of Mr. Billings, the
palaaontologist of our Survey, the specimens were confided for
examination and description to Dr. J. W. Dawson, of Montreal,
our most practised observer with the microscope ; and the
conclusions at which he has arrived are appended to this com-
munication. He finds that the serpentine, which was supposed
to replace the organic form, really fills the interspaces of the
calcareous fossil. This exhibits in some parts a well-preserved
organic structure, which Dr. Dawson describes as that of a
Foraminifer, growing in large sessile patches after the manner
of Polytrema and Carpenteria, but of much larger dimensions,
and presenting minute pohits which reveal a structure re-
sembling that of other Foraminiferal forms, as, for example
Calcarina and Nummulina.
" Dr. Dawson's description is accompanied by some remarks
by Dr. Sterry Hunt on the mineralogical relations of the fossil.
He observes that while the calcareous septa which form the
skeleton of the Foraminifer in general remain unchanged, the
sarcode has been replaced by certain silicates which have not
only filled up the chambers, cells, and septal orifices, but have
been injected into the minute tubuli, which are thus perfcctl}'
preserved, as may be seen by removing the calcareous matter
by an acid. The replacing silicates are white pyroxene, serpen-
tine, loganite, and pyrallolite or rcnsselaeritc. The pyroxene
and serpentine are often found in contact, filling contiguous
chambers in the fossil, and were evidently formed in consecu-
tive stages of a continuous process. In the Burgess specimens,
while the sarcode is replaced by loganite, the calcareous skele-
ton, as has already been stated, has been replaced by dolomite,
THE HISTORY OF A DISCOVERY.
51
and the finer parts of the structure have been almost wholly
obliterated. But in the other specimens, where the skeleton
still preserves its calcareous character, the resemblance between
the mode of preservation of the ancient Laurentian Foramini-
fera, and that of the allied forms in Tertiary and recent de-
posits (which, as Ehrenberg, Bailey, and Pourtales have shown,
are injected with glauconite), is obvious.
" The Grenville specimens belong to the highest of the three
already mentioned zones of Laurentian limestone, and it has
not yet been ascertained whether the fossil extends to the two
conformable lower ones, or to the calcareous zones of the over-
lying unconformable Upper Laurentian series. It has not yet
either been determined what relation the strata from which
the Burgess and Grand Calumet specimens have been obtained
bear to the Grenville limestone or to one another. The zone
of Grenville limestone is in some places about 1500 feet thick,
and it appears to be divided for considerable distances into
two or three parts by very thick bauds of gneiss. One of
these occupies a position towards the lower part of the lime-
stone, and may have a volume of between 100 and 200 feet.
It is at the base of the limestone that the fossil occurs. This
part of the zone is largely composed of great and small irregu-
lar masses of white crystalline pyroxene, some of them twenty
yards in length by four or five wide. They appear to be con-
fusedly placed one above another, with many ragged interstices,
and smoothly-worn, rounded, large and small pits and sub-
cylindrical cavities, some of them pretty deep. The pyroxene,
though it appears compact, presents a multitude of small
spaces consisting of carbonate of lime, and many of these
show minute structures similar to that of the fossil. These
masses of pyroxene may characterize a thickness of about 200
feet, and the interspaces among them are filled with a mixture
of serpentine and carbonate of lime. In general a sheet of
pure dark green serpentine invests each mass of pyroxene ;
the thickness of the serpentine, varying from the sixteenth of
an inch to several inches, rarely exceeding half a foot. This
is followed in different spots by parallel, waving, irregularly
alternating plates of carbonate of lime and serpentine, which
52
THE DAWN OF LIFE.
,i, ,,,„,,
become gradually finer as they recede from the pyroxene, and
occasionally occupy a total thickness of five or six inches.
These portions constitute the unbroken fossil, which may
sometimes spread over an area of about a square foot, or per-
haps more. Other parts, immediately on the outside of the
sheet of serpentine, are occupied with about the same thick-
ness of what appear to be the ruins of the fossil, broken up
into a more or less granular mixture of calc-spar and serpen-
tine, the former still showing minute structure ; and on the
outside of the whole a similar mixture appears to have been
swept by currents and eddies into rudely parallel and curving
layers ; the mixture becoming gradually more calcareous as it
recedes from the pymxene. Sometimes beds of limestone of
several feet in thickness, with the green serpentine more or
less aggregated into layers, and studded with isolated lumps
of pyroxene, are irregularly interstratified in the mass of
rock ; and less frequently there are met with lenticular patches
of sandstone or granular quartzite, of a foot in thickness and
sevei'al yards in diameter, holding in abundance small dis-
seminated leaves of graphite.
" The general character of the rock connected with the fossil
produces the impression that it is a great Foraminiferal reef,
in which the pyroxenic masses represent a more ancient por-
tion, which having died, and having become much broken up
and worn into cavities and deep recesses, afforded a seat for a
new growth of Foraminifera, represented by the calcareo-ser-
pentinous part. This in its turn became broken up, leaving
in some places uninjured portions of the general form. The
main difference between this Foraminiferal reef and more re-
cent coral-reefs seems to be that, while in the latter are usually
associated many shells and other organic remains, in the more
ancient one the only remains yet found are those of the animal
which built the reef."
(B.) Note by Sir William E. Logan, on Additional
Specimens of Eozoon.
^Journal of Geological Society, August, 1867.]
" Since the subject of Laurentian fossils was placed before
this Society in the papers of Dr. Dawson, Dr. Carpenter, Dr.
^V*"
THE HISTORY OF A DISCOVEKY.
00
le
T, Sterry Hunt, and myself, in 1865, additional specimens of
Eozoon have been obtained during the explorations of the
Geological Survey of Canada. These, as in the case of the
specimens first discovered, have been submitted to the ex-
amination of Dr. Dawson; and it will be observed, from
liis remarks contained in the paper which is to follow, that
one of them has afforded further, and what appears to him
conclusive, evidence of their organic character. The speci-
mens and remarks have been submitted to Dr. Carpenter,
who coincides with Dr. Dawson; and the object of what
I have to say in connection with these new specimens is
merely to point out the localities in which they have been
})rocured.
"The most important of these specimens was met with last
summer by Mr. G. H. Vennor, one of the assistants on the
Canadian Geological Survey, in the township of Tudor and
county of Hastings, Ontario, about forty-five miles inland
from the north shore of Lake Ontario, west of Kingston. lb
occurred on the surface of a layer, three inches thick, of dark
grey micaceous limestone or calc-schist, near the middle of a
great zone of similar rock, which is interstratified with beds of
yellowish-brown sandstone, gray close grained silicious lime-
stone, white coarsely granular limestone, and bands of dark
bluish compact limestone and black pyritiferous slates, to the
whole of which Mr. Vennor gives a thickness of 1000 feet.
Beneath this zone are gray and pink dolomites, bluish and
grayish mica slates, with conglomerates, diorites, and beds of
magnetite, a red orthoclase gneiss lying at the base. The
whole scries, according to Mr. Vennor's section, which is ap-
pended, has a thickness of more than 12,000 feet ; but the
possible occurrence of more numerous folds than have hitherto
been detected, may hereafter render necessary a considerable
reduction.
" These measures appear to be arranged in the form of a
trough, to the eastward of which, and probably beneath them,
there are rocks resembling those of Grenville, from which the
former differ considerably in lithological character ; it is there-
fore supposed that the Hastings series may be somewhat
it
'il H^ W!
m
54
THE DAWN OF LIFE.
:Jl
I
Mil
R>'.
|l!li
, !■„,
i
higher in horizon than that of Grenville. From the village of
Madoc, the zone of gray micaceous limestone, which has been
particularly alluded to, runs to the eastward on one side of the
trough, in a nearly vertical position into Elzivir, and on the
other side to the northward, through the township of Madoc
into that of Tudor, partially and unconformably overlaid in
several places by horizontal beds of Lower Silurian limestone,
but gradually spreading, from a diminution of the dip, from
a breadth of half a mile to one of four miles. Where it thus
spreads out in Tudor it becomes suddenly interrupted for a
considerable part of its breadth by an isolated muss of anortho-
site rock, rising about 150 feet above the general plain, and
supposed to belong to the unconformable Upper Laurentian."
[Subsequent observations, however, render it probable that
some of the above beds may be Huronian.]
"The Tudor limestone is comparatively unaltered : and, in the
specimen obtained from it, the general form or skeleton of the
fossil (consisting of white carbonate of lime) is imbedded in
the limestone, without the presence of serpentine or other
silicate, the colour of the skeleton contrasting strongly with
that of the rock. It does not sink deep into the rock, the
form having probably been loose and much abraded on what
is now the under part, before being entombed. On what was
the surface of the bed, the form presents a well-defiued out-
line on one side ; in this and in the arraugement of the septal
layers it has a marked resemblance to the specimen first
brought from the Calumet, eighty miles to the north-east, and
figured in the Geology of Canada, p. 49 ; while all the forms
from the Calumet, like that from Tudor, are isolated, imbedded
specimens, unconnected apparently with any continuous reef,
such as exists at Grenville and the Petite Nation. It will be
seen, from Dr. Dawson's paper, that the minute structure is
present in the Tudor specimen, though somewhat obscure;
but in respect to this, strong subsidiary evidence is derived
from fragments of Eozoon detected by Dr. Dawson in a speci-
men collected by myself from the same zone of limestone near
the village of Madoc, in which the canal-system, much more
distinctly displayed, is filled with carbonate of lime, as quoted
THE HISTORY OF A DISCOVERY. OU
from Dr. Dawson by Dr. Carpenter in the Journal of this
Society for August, 186G.
** In Dr. Dawson's paper mention is made of ppecimens
from Wentworth, and others from Long Lake. In both of
these localities the rock yielding them belongs to the Gren-
ville band, which is the uppermost of the three great bands of
limestone hitherto described as interstratified in the Lower
Laurentian series. That at Long Lake, situated about twenty-
five miles north of Cote Sfc. Pierre in the Petite Nation
seigniory, where the best of the previous specimens were
obtained, is in the direct run of the limestone there : and like
it the Long Lake rock is of a serpentinous character. The
locaHty in Wentworth occurs on Lake Louisa, about sixteen
miles north of east from that of the first Grenville specimens,
from which Cote St. Pierre is about the same distance north
of west, the lines measuring these distances running across
several important undulations in the Grenville band in both
directions. The Wentworth specimens are imbedded in .1
portion of the Grenville band, which appears to have escaped
any great alteration, and is free from serpentine, though a
mixture of serpentine with white crystalline limestone occurs
in the band within a mile of the spot. From this grey lime-
stone, which has somewhat the aspect of a conglomerate,
specimens have been obtained resembling some of the figures
given by Giimbel in his Illustrations of the forms met with
by him in the Laurentian rocks of Bavaria.
" In decalcifying by means of a dilute acid some of the
specimens from Cote St. Pierre, placed in his hands in 1864-65,
Dr. Carpenter found that the action of the aci,d was arrested
at certain portions of the skeleton, presenting a yellowish-
brown surface ; and he showed me, two or three weeks ago,
that in a specimen recently given him, from the same locality,
considerable portions of the general form remained undissolved
by such an acid. On partially reducing some of these portions
to a powder, however, we immediately observed effervescence
by the dilute acid ; and strong acid produced it without bruis-
ing. There is little doubt that these portions of the skeleton
are parti.illy replaced by dolomite, as more recent fossils are
^1
■^TT
50
THE DAWN OF LIFE.
ii|i::'i
often known to be, of which there is a noted instance in the
Trenton limestone of Ottawa. But the circumstance is alhided
to for the purpose of comparing these dolomitized portions of
the skeleton with the specimens from Burgess, in which the
replacement of the septal layers by dolomite appears to be the
general condition. In such of these specimens as have been
examined the minute structure seems to be wholly, or almost
wholly, destroyed ; but it is probable that upon a further in-
vestigation of the locality some spots will be found to yield
specimens in which the calcareous skeleton still exists unre-
placed by dolomite ; and I may safely venture to predict that
in such specimens the minute structure, in respect both to
canals and tubuli, will be found as well preserved as in any of
the specimens from Cote St. Pierre.
" It was the general form on weathered surfaces, and its
strong resemblance to Stromatopora, which first attracted my
attention to Eozoon ; and the persistence of it in two distinct
minerals, pyroxene and loganite, emboldened me, in 1857, to
place before the Meeting of the American Association for the
Advancement of Science specimens of it as probably a Lauren-
tian fossil. After that, the form was found preserved in a third
mineral, serpentine ; and in one of the previous specimens it
was then observed to pass continuously through two of the min-
erals, pyroxene and serpentine. Now we have it imbedded in
limestone, just as most fossils are. In every case, with the ex-
ception of the Burgess specimens, the general form is composed
of carbonate of lime; and we have good grounds for supposing
it was originally so in the Burgess specimens also. If, there-
fore, with such evidence, and without the minute structure, I
was, upon a calculation of chances, disposed, in 1857, to look
upon the form as organic, much more must I so regard it when
the chances have been so much augmented by the subsequent
accumulation of evidence of the same kind, and the addition
of the minute structure, as described by Dr. Dawson, whose
observations have been confirmed and added to by the highest
British authority upon the class of animals to which the form
has been referred, leaving in my mind no room whatever for
doubt of its organic character. Objections to it as an or-
b
n
cl
C(
a
cl
ti
of
to
III
ro
THE mSTORY OF A DISCOVERr.
0(
gaiiism have been made by Professors King and Rowncy : but
ilieso appear to me to bo based upon the supposition that be-
cause some parts simulating organic structure are undoubtedly
mere mineral arrangement, therefore all parts are mineral. Dr.
Dawson has not proceeded upon the opposite supposition, that
because some parts are, in his opinion, undoubtedly organic,
therefore all parts simulating organic structure are organic ;
but he has carefully distinguished between the mineral and
organic arrangements. I am aware, from having supplied him
vfitb a vast number of specimens prepared for the microscope
hy the lapidary of the Canadian Survey, from a series of rocks
of Silurian and Huronian, as well as Laurentiau age, and from
having followed the course of his investigation as it proceeded,
that nearly all the points of objection of Messrs. King and
Rowney passed in review before him prior to his coming to
the conclusions which he has published."
./
Ascending Section of the Eozolc RocJcs in the County of
Hastings, Ontario. By Mr. H. G. Vennok.
1. Eeddishandflesh-colouredgranitic gneiss, the thick- Feet,
ness of which is unknown ; estimated at not less than 2,000
2. Grayish and flesh-coloured gneiss, sometimes horn-
blendic, passing towards the summit into a dark mica-
schist, and including portions of greenish- white diorite ;
mean of several pretty closely agreeing measurements, 10,400
3. Crystalline limestone, sometimes magnesian, in-
cluding lenticular patches of quartz, and broken and
contorted layers of quartzo-felspathic rock, rarely above
a few inches in thickness. This limestone, which in-
cludes in Elzivir a one-foot bed of graphite, is some-
times very thin, but in other places attains a thickness
of 750 feet ; estimated as averaging 400
4. Hornblendic and dioritic rocks, massive or schis-
tose, occasionally associated near the base with dark
micaceous schists, and also with chloritic and epidotic
rocks, including beds of magnetite; average thickness 4,200
5. Crystalline and somewhat granular magnesian
58
THE DAWN OF LIFE.
limestone, occasionally interstratified with diorites, and
near the baao with silicious slates and small beds of
impure steatite 330
This limestone, which is often silicious and ferrugin-
ous, is metalliferous, holding disseminated copper
pyrites, blende, mispickcl, and iron pyrites, the latter
also sometimes in beds of two or three feet. Gold occurs
in the limestone at the village of Madoc, associated with
an argentiferous gray copper ore, and in irregular veins
with bitter-spar, quartz, and a carbonaceous matter, at
the Hichardson mine in Madoc.
6. Gray silicious or fined-grained mica-slates, with
an interstratified mass of about sixty feet of yellowish-
white dolomite divided into beds by thin layers of the
mica-slate, which, as well as the dolomite, often becomes
conglomerate, including rounded masses of gneiss and
quartzite from one to twelve inches in diameter 400
7. Bluish and grayish micaceous slate, interstratified
with layers of gneiss, and occasionally holding crystals
of magnetite. The whole division weathers to a rusty-
brown 500
8. Gneissoid micaceous quartzites, banded gray and
white, with a few instratified beds of silicious lime-
stone, and, like the last division, weathering rusty
brown 1,900
9. Gray micaceous limestone, sometimes plumbagin-
ous, becoming on its upper portion a calc-schist, but
more massive towards the base, where it is interstratified
with occasional layers of diorite, and layers of a rusty-
weathering gneiss likeS 1,100
This division in Tudor is traversed by numerous
N.W. and S.E. veins, holding galena in a gangue of
calcite and barytine. The Eozoon from Tudor here
described was obtained from about the middle of this
calcareous division, which appears to form the summit
of the Hastings series.
Total thickness 21,130
I :,., m
Plate IV
i' .ill'.
•: i
(■■'■tt
( >
MaijniiU'd and hectored Section of a portion of Eozoon Canadenxt'-
Tlio |)ort.ions in ))ro\vn kU'>\v the animal mnllei- of the Chunihers, Tnbuli,
Ciinals, and r.sciulopiMliji ; ilie portions uucoloureil, the calciireous skeleton.
Hillil:!
CHAPTER TV.
WHAT IS EOZOON .
TuE sliortest answer to this question is, tliattliis ancient
fossil is the skeleton of a creature belonging to that
simple and humbly organized group of animals whicli
are known by the name Protozoa. If we take as a
familiar example of these the gelntinous and microscopic
creature found in stagnant pond.s, and known as the
Amoeba^ (fig. 12), it will form, a convenient starting
point. Viewed under a low power, it appears as a
little patch of jelly, irregular in form, and constantly
changing i^s aspect as it moves, by the extension of
parts of its body into finger-like processes or pseudo-
pods which serve as extempore limbs. When moving
on the surface of a slip of glass under the microscope,
it seems, as it were, to flow along rather than creep,
and its body appears to be of a semi-fluid consistency.
It may be taken as an example of the least complex
forms of animal life known to us, and is often spoken
of by naturalists as if it were merely a little particle
of living and scarcely organized jelly or protoplasm.
When minutely examined, however, it will not be found
so simple as it at first sight appears. Its outer layer
* The alternating animal, alluding to its change of form.
1" t
"^j:^
i lit
■I* ;
i.";'
jJill
GO
THE DAWN OF LIFE.
is clear or transparent^, and more dense than the inner
mass^ which seems granular. It has at one end a
curious vesicle which can be seen gradually to expand
and become filled with a clear drop of liquid, and then
suddenly to contract and expel the contained fluid
through a series of pores in the adjacent part ui the
outer wall. This is the so-called pulsating vesicle, and
is an organ both of circulation and excretion. In
anotlier part of the body may be seen the nucleus,
; / > \
/ /
Fig. 12. Amceha. Fio. 13. Actinophrys.
From original sketches.
which is a little cell capable, at certain times, of pro-
ducing by its division new individuals. Food when
taken in through the wall of the body forms little
pellets, which become surrounded by a digestive liquid
exuded from the enclosing mass into rounded cavities
or extemporised stomachs. Minute granules are seen
to circulate in the gelatinous interior, and may be
substitutes for blood- cells, and the outer layer of the
u
WHAT IS EOZOON ?
61
body is capable of protrusion in any direction into long
processes, whioh are very mobile, and used for locomo-
tion and prehension. Further, this creature, though
destitute of most of the parts which we are accustomed
to regard as proper to animals, seems to exercise voli-
tion, and to show the same appetites and passions with
animals of higher type. I have watched one of these
animalcules endeavouring to swallow a one-celled plant
as long as its own body ; evidently hungry and eager to
devour the tempting morsel, it stretched itself to its
full extent, trying to envelope the object of :ts desire.
It failed again and again ; but renewed the attempt,
until at length, convinced of its hopelessness, it flung
itself away as if in disappointment, and made off in
search of something? more manaoreable. With the
Amoeba are found other types of equally simple Pro-
tozoa, but somewhat differently organized. One of
these, Aduiophrys (fig. 13), has the body globular and
unchanging in form, the outer wall of greater thick-
ness ; the pulsating vesicle like a blister on the surface,
and the pseudopods long and thread-like. Its habits
are similar to those of the Amoeba, and I introduce it
to show the variations of form and structure possible
even among these simple creatures.
The Amooba and Actinophrys are fresh water animals,
and are destitute of any shell or covering. But in the sea
there exist swarms of similar creatures, equally simple
in organization, but gifted with the power of secreting
around their soft bodies beautiful little shells or crusts
of carbonate of lime, having one orifice, and often in
^ f
■ii!!
62
THE DAWN OP LIFE.
iHl'l^ii'
Fig. 14. Entosolenia.
A one-ceilod Foraminifcr. Magnified as a ti'ansparent object.
Fig. 15. Biloculina.
A many-chumberod Foraminifer. Magnified as a tranapai-oul object.
d\'
Fiu. 10. rolystomellu.
A spiral I oraminifcr. Mngniflcd as an opniiuc object.
it
WHAT IS EOZOON T
CG
addition multitudes of microscopic pores tlirougli which
the soft gelatinous matter can ooze, and form outside
iinger-like or thread-like extensions for collecting food.
In some cases the shell consists of a single cavity only,
but in most, after one cell is completed, others are added,
forming a series of cells or chambers communicatiug
with each other, and often arranged spirally or other-
wise in most beautiful and symmetrical forms. Some
of these creatures, usually named Foramiiiifera, arc
I'lu. 17. FuLijmorphina.
A many-clinmberecl Foriuninifer. Macfiiifled as an opaque object. Figs, li to
17 are from original skctcijcs of Post-pliocene si)ecimeus.
locomotive, others sessile and attached. Most of them
are microscopic, but some grow by multiplication of
chambers till they are a quarter of an inch or more in
breadth. (Figs. 14 to 17.)
The original skeleton or primary cell-wall of most of
these creatures is seen under the microscope to be per-
forated with innumerable pores, and is extremely thiu.
When, however, owing to the increased size of the
shell, or other wants of the creature, it is necessary to
1. 1'
1 1-
64
THE DAWN OF LIFE.
give strength, this is done by adding new portions of
carbonate of lime to the outside, and to these Dr. Car-
penter has given the appropriate name of " supplemen-
tal skeleton ; '^ and this, when covered by new growths,
becomes what he has termed an " intermediate skele-
ton." The supplemental skeleton is also traversed by
tubes, but these are often of larger size than the pores
of the cell-wall, and of greater length, and branched in
a complicated manner. (Fig. 20.) Thus there are micro-
scopic characters by which these curious shells can be
distinguished from those of other marine animals ; and
by applying these characters we learn that multitudes
of creatures of this type have existed in former periods
of the world's history, and that their shells, accumulated
in the bottom of the sea, constitute large portions of
many limestones. The manner in which such accumu-
lation takes place we learn from what is now going on
in the ocean, more especially from the result of the
recent deep-sea dredging expeditions. The Foramini-
fera are vastly numerous, both near the surface and at
the bottom of the sea, and multiply rapidly ; and as
successive generations die, their shells accumulate on
the ocean bed, or are swept by currents into banks,
and thus in process of time constitute thick beds of
white chalky material, which may eventually be hard-
ened into limestone. This process is now depositing a
great thickness of white ooze in the bottom of the
ocean ; and in times past it has produced such vast
thicknesses of calcareous matter as the chalk and
the nummulitic limestone of Europe and the orbitoidal
WHAT IS EOZOON ?
05
hi
1 -
rimestone of America. The chalk, which alone
attains a maximum thickness of 1000 feet, and,
according to Lyell, can be traced across Europe for
1100 geographical miles, may be said to be entirely
composed of shells of Foraminifera imbedded in a paste
of still more minute calcareous bodies, the Coccoliths,
which are probably products of marine vegetable life,
if not of some animal organism still simpler than the
Foraminifera.
Lastly, we find that in the earlier geological ages
there existed much larger Foraminifera than any found
in our present seas ; and that these, always sessile on
the bottom, grew by the addition of successive chambers,
in the same manner with the smaller species. To some
of these we shall return in the sequel. In the mean-
time we shall see what claims Eozoon has to be in-
cluded among them.
Let us, then, examine the structure of Eozoon, taking
a typical specimen, as we find it in the limestone of
Grenville or Petite Nation. In such specimens the
skeleton of the animal is represented by a white crys-
talline marble, the cavities of the cells by green serpen-
tine, the mode of whose introduction we shall have to
consider in the sequel. The lowest layer of serpentine
represents the first gelatinous coat of animal matter
which grew upon the bottom, and which, if we could
have seen it before any shell was formed upon its
surface, must have resembled, in appearance at least,
the shapeless coat of living slime found in some portions
of the bed of the deep sea, which has received from
.
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I'.ii
■!i
THE DAWN OF LIFE.
Huxley the name Bathyhius, and which is believed to be
a protozoon of indefinite extension, though it may
possibly be merely the pulpy sarcode of sponges and
similar things penetrating the ooze at their bases. On
this primary layer grew a delicate calcareous shell, per-
forated by innumerable minute tubuli, and by some
larger pores or septal orifices, while supported at inter-
vals by perpendicular plates or pillars. Upon this again
was built up, in order to strengthen it, a thickening
or supplemental skeleton, more dense, and destitute of
fine tubuli, but traversed by branching canals, through
which the soft gelatinous matter could pass for the
nourishment of the skeleton itself, and the extension of
pseudopods beyond it. (Fig. 10.) So was formed the
first layer of Eozoon, which seems in some cases to
have spread by lateral extension over several inches
of sea bottom. On this the process of growth of succes-
sive layers of animal sarcode and of calcareous skeleton
was repeated again and again, till in some cases even a
hundred or more layers were formed. (Photograph,
Plate III., and nature print, Plate Y.) As the process
went on, however, the vitality of the organism became
exhausted, probably by the deficient nourishment of
the central and lower layers making greater and greater
demands on those above, and so the succeeding
layers became thinner, and less supplemental skeleton
was developed. Finally, toward the top, the regular
arrangement in layers was abandoned, and the cells
became a mass of rounded chambers, irregularly piled
up iu what Dr. Carpenter has termed an "acervuline "
WHAT IS EOZOON?
67
manner, and with very thin walls unprotected by sup-
plemental skeleton. Then the growth was arrested,
and possibly these upper layers gave off reproductive
germs, fitted to float or swim away and to establish
new colonies. We may have such reproductive germs
in certain curious globular bodies, like loose cells, found
in connection with irregular Eozoon in one of the
Laurentian limestones at Long Lake and elsewhere.
s
e
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V
W
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Fig. 18. Minute Foraminiferal forms from the Laurentian of Long
Lake.
Highly magnified, (a.) Single cell, showing tubulated wall, (b, c.) Portions of
same move highly msignifled. (d.) Serpentine cast of a similar chamber,
decalcifiod, and showing casts of tubuli.
These curious organisms I observed some years ago,
but no description of them was published at the time,
as I hoped to obtain better examples. I now figure
some of them, and give their description in a note.
(Fig. 18) . I have recently obtained numerous additional
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68
THE DAWN OF LIFE.
examples from the beds holding Eozoon at St. Pierre,
on the Ottawa. They occur at this place on the sur-
face of layers of the Kmestone in vast numbers, as if
they had been growing separately on the bottom, or
had been drifted over it by currents. These we shall
further discuss hereafter. Such was the general mode
of growth of Eozoon, and we may now consider more in
detail some questions as to its gigantic size, its precise
mode of nutrition, the arrangement of its parts, its rela-
tions to more modern forms, and the effects of its growth
in the Laurentian seas. In the meantime a study of
our illustration, Plate IV., which is intended as a magni-
fied restoration of the animal, will enable the reader
distinctly to understand its structure and probable
mode of growth, and to avail himself intelligently of
the partial representations of its fossilised remains in
the other plates and woodcuts.
With respect to its size, we shall find in a subsequent
chapter that this was rivalled by some succeeding
animals of the same humble type in the Silurian age ;
and that, as a whole, foraminiferal animals have been
diminishing in size in the lapse of geological time. It
is indeed a fact of so frequent occurrence that it may
almost be regarded as a law of the introduction of new
forms of life, that they assume in their early history
gigantic dimensions, and are afterwards continued by
less magnificent species. The relations of this to ex-
ternal conditions, in the case of higher animals, are often
complex and difficult to understand ; but in organisms
so low as Eozoon and its allies, they lie more on the
Jill
WHAT IS EOZOON ?
69
surface. Such creatures may bo regarded as the
simplest and most ready media for the conversion of
vegetable matter into animal tissues, and their functions
are almost entirely limited to those of nutrition. Hence
it is likely that they will be able to appear in the most
gigantic forms under such conditions as afford them
the greatest amount of pabulum for the nourishment
of their soft parts and for their skeletons. There is
reason to believe, for example, that the occurrence, both
in the chalk and the deep-sea mud, of immense quantities
of the minute bodies known as Coccoliths along with
Foraminifera, is not accidental. The Coccoliths appear
to be grains of calcareous matter formed in minute
plants adapted to a deep-sea habitat ; and these, along
with the vegetable and animal debris constantly being
derived from the death of the living things at the sur-
face, afford the material both of sarcode and shell.
Now if the Laurentian graphite represents an exuber-
ance of vegetable growth in those old seas proportionate
to the great supplies of carbonic acid in the atmosphere
and in the waters, and if the Eozoic ocean was even
better supplied with carbonate of lime than those
Silurian seas whose vast limestones bear testimony to
their richness in such material, we can easily imagine
that the conditions may have been more favourable to
a creature like Eozoon than those of any other period
of geological time.
Growing, as Eozoon did, on the floor of the ocean, and
covering wide patches with more or less irregular
masses, it must have thrown up from its whole surface
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THE DAWN OP LIFE.
its pseudopods to seize whatever floating particles of
food the waters carried over it. There is also reason
to believe, from the outline of certain specimens, that it
often grew upward in cylindrical or club-shaped forms,
and that the broader patches were penetrated by large
pics or oscula, admitting the sea-water deeply into the
substance of the masses. In this way its growth
might be rapid and continuous ; but it does not seem
to have possessed the power of growing indefinitely by
new and living layers covering those that had died, in
the manner of some corals. Its life seems to have had
a definite termination, and when that was reached an
entirely new colony had to be commenced. In this it
had more affinity with the Foraminifera, as we now
know them, than with the corals, though practically it
had the same power with the coral polyps of accumu-
lating limestone in the sea bottom, a power indeed still
possessed by its foraminiferal successors. In the
case of coral limestones, we know that a large propor-
tion of these consist not of continuous reefs but of
fragments of coral mixed with other calcareous organ-
isms, spread usually by waves and currents in con-
tinuous beds over the sea bottom. In like manner we
find in the limestones containing Eozoon, layers of frag-
mental matter which shows in places the characteristic
structures, and which evidently represents the debris
swept from the Eozoic masses and reefs by the action of
the waves. It is with this fragmental matter that the
small rounded organisms already referred to most fre-
quently occur; and while they may be distinct
WHAT IS EOZOON ?
71
animals, they may also be the fry of Eozoou, or small
portions of its acervuline upper surface floated off in a
living state, and possibly capable of living indepen-
dently and of founding new colonies.
It is only by a somewhat wild poetical licence that
Eozoon has been represented as a " kind of enormous
composite animal stretching from the shores of Labrador
to Lake Superior, and thence northward and south-
ward to an unknown distance, and forming masses
1500 feet in depth/' We may discuss by-and-by the
question of the composite nature of masses of Eozoon,
and we see in the corals evidence of the great size to
which composite animals of a higher grade can attain.
In the case of Eozoon we must imagine an ocean floor
more uniform and level than that now existing. On
this the organism would establish itself in spots and
patches. These might finally become confluent over
large areas, just as massive corals do. As individual
masses attained maturity and died, their pores would be
filled up with limestone or silicious deposits, and thus
could form a solid basis for new generations, and in
this way limestone to an indefinite extent might be
produced. Further, wherever such masses were high
enough to be attacked by the breakers, or where por-
tions of the sea bottom were elevated, the more fragile
parts of the surface would be broken up and scattered
widely in beds of fragments over the bottom of the sea,
while here and there beds of mud or sand or of volcanic
debris would be deposited over the living or dead
organic mass, and would form the layers of gneiss
11
THE DAWN OF LIFE.
and other schistose rocks interstratified with the
Laurentian limestone. In this way, in short, Eozoon
would perform a function combining that which corals
and Foraminifera perform in the modern seas ; forming
both reef limestones and extensive chalky beds, and
probably living both in the shallow and the deeper
parts of the ocean. If in connection with this we con-
sider the rapidity with which the soft, simple, and
almost structureless sarcode of these Protozoa can be
built up, and the probability that they were more
abundantly supplied with food, both for nourishing their
soft parts and skeletons, than any similar creatures in
later times, we can readily understand the great
volume and extent of the Laurentian limestones which
they aided in producing. I say aided in producing,
because I would not desire to commit myself to the
doctrine that the Laurentian limestones are wholly of
this origin. There may have been other animal lime-
stone-builders than Eozoon, and there may have been
limestones formed by plants like the modem Nullipores
or by merely mineral deposition.
Its relations to modern animals of its type have been
very clearly defined by Dr. Carpenter. In the structure
of its proper wall and its fine parallel perforations, it
resembles the Niimmiilites and their allies; and the
organism may therefore be regarded as an aberrant
member of the Nummuline group, which affords some
of the largest and most widely distributed of the fossil
Foraminifera. This resemblance may be seen in fig.
19. To the Nummulites it also conforms in its
WHAT IS EOZOON ?
73
tendency to form a supplemental or intermediate skele-
ton with canals, though the canals themselves in their
arrangement more nearly resemble Calcarina, which
T/,'/
\
Fig. 19. Section of a Nummulite, from Eocene Limestone of Syria.
Showing chambors, tubnll, and canals. Compare this and fig. 20 with figs. 10
and 11.
Fig. 20. Portion of shell of Calcarina.
Magnified, after Carpenter, (a.) Cells, (b.) Original cell-wall with tubuli. Ic.)
Supplementary skeleton with canals.
is represented in fig. 20. In its superposition of many
layers, and in its tendency to a heaped up or acervuline
irregular growth it resembles Polytrema and Tinojioriis ,
■A:
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74
THE DAWN OF LIFE.
forms of a different group in so far as sliell-structure is
concerned. It may thus be regarded as a composite
type, combining peculiarities now observed in two
groups, or it may be regarded as a representative in the
Nummuline series of Polytrema and Tinoporus in the
Rotaline series. At the time when Dr. Carpenter stated
these affinities, it might be objected that Foraminifera
of these families are in the main found in the Modern
and Tertiary periods. Dr. Carpenter has since shown
that the curious oval Foraminifer called FusuUna, found
in the coal formation, is in like manner allied to both
Nummulites and Eotalines ; and still more recently
Mr. Brady has discovered a true Nummulite in the
Lower Carboniferous of Belgium. This group being
now fairly brought down to the Palaeozoic, we may hope
finally to trace it back to the Primordial, and thus to
bring it still nearer to Eozoon in time.
Though Eozoon was probably not the only animal of
the Laurentian seas, yet it was in all likelihood the
most conspicuous and important as a collector of cal-
careous matter, filling the same place afterwards
occupied by the reef -building corals. Though pro-
bably less efficient than these as a constructor of solid
limestones, from its less permanent and continuous
growth, it formed wide floors and patches on the sea-
bottom, and when these were broken up vast quantities
of limestone were formed from their debris. It must
also be borne in mind that Eozoon was not everywhere
infiltrated with serpentine or other silicious minerals ;
quantities of its substance were merely filled with car-
WHAT IS EOZOON T 7o
bonate of lime, resembling the cbamber-wall so closely
that it is nearly impossible to make out the difference,
and thus is likely to pass altogether unobserved
by collectors, and to baffle even the microscopist.
(Pig. 24.) Although therefore the layers which contain
well characterized Eozoon are few and far between.
'A
Fig. 21. Foraminiferal Rock Builders.
(a.) Nummulites Irovigata— Eocene, (b.) The same, showinff chamberorl in-
terior, (c.) Milioline limestone, magnified— Eocene, Paris, (tl.) Hard
Chalk, section magnified— Cretaceous.
there is reason to believe that in the composition of the
limestones of the Laurentian it bore no small part, and
as these limestones are some of them several hundreds
of feet in thickness, and extend over vast areas, Eozoon
may be supposed to have been as efficient a world-
builder as the Stromatoporae of the Silurian and.
lijil
fill it
7G
THE DAWN OF LIFE.
Devonian, the Globigeringa and their allies in the chalk,
or the Nummulites and Miliolites in the Eocene. The
two latter groups of rock-makers are represented in
our cut, fig. 21; the first will engage our attention in
chapter sixth. It is a remarkable illustration of the
constancy of natural causes and of the persistence of
animal types, that these humble Protozoans, which be-
gan to secrete calcareous matter in the Laurentian
period, have been continuing their work in the ocean
through all the geological ages, and are still busy in
accumulating those chalky muds with which recent
dredging operations in the deep sea have made us so
familiar.
NOTES TO CHAPTER IV.
(A.) OniGiNAL Description of Eozoon Oanadense.
[As given by the author in the Journal of the Geological Society,
February, 1865.]
" At the request of Sir W. E. Logan, I have submitted to
microscopic examination slices of certain peculiar laminated
forms, consisting of alternate layers of carbonate of lime and
serpentine, and of carbonate of lime and white pyroxene,
found in the Laurentian limestone of Canada, and regarded by
Sir William as possibly fossils. I have also examined slices
of a large number of limestones from the Laurentian series,
nob shovring the forms of these supposed fossils.
" The specimens first mentioned are masses, often several
inches in diameter, presenting to the naked eye alternate
laminsa of serpentine, or of pyroxene, and carbonate of lime.
Their general aspect, as remarked by Sir W. E. Logan
{Geology of Canada, 1863, p. 49), reminds the observer of that
of the Silurian corals of the genus Stromatopora, except that
WHAT IS EOZOON ?
77
1^
CD
I /
1 i
the laminae diverge from and approach each other, and fre-
quently anastomose or are connected by transverse septa.
" Under the microscope the resemblance to Stromatopora is
seen to be in general form merely, and no trace appears of the
radiating pillars characteristic of that genus. The lamince of
serpentine and pyroxene present no organic structure, and the
latter mineral is highly crystalline. The laminae of carbonate
of lime, on the contrary, retain distinct traces of structures
which cannot be of a crystalline or concretionary character.
They constitute parallel or concentric partitions of variable
thickness, enclosing flattened spaces or chambers, frequently
crossed by transverse plates or septa, in some places so
numerous as to give a vesicular appearance, in others oc-
curring only at rare intervals. The laminae themselves are
excavated on their sides into rounded pits, and are in some
places traversed by canals, or contain secondary rounded cells,
apparently isolated. In addition to these general appearances,
the substance of the laminae, where most perfectly preserved,
is seen to present a fine granular structure, and to be pene-
trated by numerous minute tubuli, which are arranged in
bundles of great beauty and complexity, diverging in sheaf-
like forms, and in their finer exten' ? anastomosing so as to
form a network (figs. 10 and 28). •. transverse sections,
and under high powers, the tubuli are seen to be circular
in outline, and sharply defined (fig. 29). In longitudinal
sections, they sometimes present a beaded or jointed appear-
ance. Even where the tubular structure is least perfectly
preserved, traces of it can still be seen in most of the slices,
though there are places in which the lamina are perfectly
compact, and perhaps were so originally.
" With respect to the nature and probable origin of the
appearances above described, I would make the following
remarks : —
•* 1. The serpentine and pyroxene which fill the cavities of
the calcareous matter have no appearance of concretionary
structure. On the contrary, their aspect is that of matter
introduced by infiltration, or as sediment, and filling spaces
previously existing. In other words, the calcareous matter
I ll
73
THE DAWN OF LIFE.
Las not been moulded on the forms of the serpentine and
augite, but these have filled spaces or chambers in a hard cal-
careous mass. This conclusion is further confirmed by the
fact, to bo referred to in the sequel, that the serpentine in-
cludes multitudes of minute foreign bodies, while the cal-
careous matter is uniform and homogeneous. It is also to be
observed that small veins of carbonate of lime occasionally
traverse the specimens, and in their entire absence of struc-
tures other than crystalline, present a striking contrast to the
supposed fossils.
" 2. Though the calcareous laminae have in places a crystal-
line cleavage, their forms and structures have no relation to
this. Their cells and canals are rounded, and have smooth
walls, which are occasionally lined with films apparently of
carbonaceous matter, Above all, the minute tubuli are
diflerent from anything likely to occur in merely crystalline
calc-spar. While in such rocks little importance might be
attached to external forms simulating the appearances of
corals, sponges, or other organisms, these delicate internal
structures have a much higher claim to attention. Nor is
there any improbability in the preservation of such minute
parts in rocks so highly crystalline, since it is a circumstance
of frequent occurrence in the microscopic examination of
fossils that the finest structures are visible in specimens in
which the general form and the arrangement of parts have
been obliterated. It is also to be observed that the structure
of the calcareous laminaD is the same, whether the intervening
spaces are filled with serpentine or with pyroxene.
" 3. The structures above described are not merely definite
and uniform, but they are of a kind proper to animal organ-
isms, and more especially to one particular type of animal
life, as likely as any other to occur under such circumstances :
I refer to that of the Rhizopods of the order Foraminifera.
The most important point of difference is in the great size and
compact habit of growth of the specimens in question ; but
there seems no good reason to maintain that Foraminifera
must necessarily be of small size, more especially since forms
of considerable magnitude referred to this type are known in
WHAT IS EOZOON ?
79
the Lower Silurian. Professor Hall has described specimens
of Eeceptaculites twelve inches in diameter ; and the fossils
from the Potsdam formation of Labrador, referred by Mr.
Billings to the genus Archaeocyathus, are examples of Protozoa
with calcareous skeletons scarcely inferior in their massive
style of growth to the forms now under consideration.
"These reasons are, I think, sufficient to justify me in re-
garding these remarkable structures as truly organic, and
in searching for their nearest allies among the Foramiiii-
fera.
" Supposing then that the spaces between the calcareous
lamince, as well as the canals and tubuli traversing their sub-
stance, were once filled with the sarcode body of a Rhizopod,
comparisons with modern forms at once suggest themselves.
"From the polished specimens in the Museum of the
Canadian Geological Survey, it appears certain that these
bodies were sessile by a broad base, and grew by the addition
of successive layers of chambers separated by calcareous
laminae, but communicating with each other by canals or
septal orifices sparsely and irregularly distributed. Small
specimens have thus much the aspect of the modem genera
Carpenteria and Polytrema. Like the first of these genera,
there would also seem to have been a tendency to leave in
the midst of the structure a large central canal, or deep
funnel-shaped or cylindrical opening, for communication with
the sea-water. Where the laminra coalesce, and the structure
becomes more vesicular, it assumes the ' acervuline ' charac-
ter seen in such modern forms as Nubecularia.
" Still the magnitude of these fossils is enormous when
compared with the species of the genera above named; and
from the specimens in the larger slabs from Grenvillo, in
the museum of the Canadian Survey, it would seem that these
organisms grew in groups, which ultimately coalesced, and
formed large masses penetrated by deep irregular canals;
and that they continued to grow at the surface, while the
lower parts became dead and were filled up with infiltrated
matter or sediment. In short, we have to imp,gine an organ-
ism having the habit of growth of Carpenteria, but attaining
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30
THE DAWN OF LIFE.
to an enormous size, and by the aggregation of individuals
assuming the aspect of a coral reef.
" The complicated systems of tubuli in the Laurentian fossil
indicate, however, a more complex structure than that of any
of the forms mentioned above. I have carefully compared
these with the similar structures in the 'supplementary
skeleton* (or the shell-substance that carries the vascular
system) of Calcarina and other forms, and can detect no
difference except in the somewhat coarser texture of the tubuli
in the Laurentian specimens. It accords well with the great
dimensions of these, that they should thus thicken their walls
with an extensive deposit of tubulated calcareous matter; and
from the frequency of the bundles of tubuli, as well as from
the thickness of the partitions, I have no doubt that all the
successive walls, as they were formed, were thickened in this
manner, just as in so many of the higher genera of more
modern Foraminifera.
" It is proper to add that no spicules, or other structures
indicating affinity to the Sponges, have been detected in any
of the specimens.
" As it is convenient to have a name to designate these
forms, I would propose that of Eozoon, which will be specially
appropriate to what seems to be the characteristic fossil of a
group of rocks which must now be named Eozoic rather than
Azoic. For the species above described, the specific name of
Canadense has been proposed. It may be distinguiahed by
the following characters : —
" EozooN Canadense ; gen. et spec. nov.
** General form. — Massive, in large sessile patches or ir-
regular cylinders, growing at the surface by the addition of
successive laminas.
"Internal structure. — Chambers large, flattened, irregular,
with numerous rounded extensions, and separated by walls of
variable thickness, which are penetrated by septal orifices
irregularly disposed. Thicker parts of the walls with bundles
of fine branching tubuli.
"These characters refer specially to the specimens from
Grenville and the Calumet. There are others from Perth,
^i
"WHAT IS EOZOON ?
SI
C. W., which show more regular lamina}, aud in vrhich the
tubuli have not yet been observed; and a specimen from
Burgess, C. W., contains some fragments of laminae which
exhibit, on one side, a series of fine parallel tubuli like those
of Nuramulina. These specimens may indicate distinct
species ; but on the other hand, their peculiarities may de-
pend on different states of preservation.
** With respect to this last point, it may be remarked that
some of the specimens from Grenville and the Calumet show
the structure of the laminao with nearly equal distinctness,
whether the chambers are filled with serpentine or pyroxene,
and that even the minute tubuli are penetrated and filled with
these minerals. On the other hand, there are large specimens
in the collection of the Canadian Survey in which the lower
and still parts of the organism are imperfectly preserved in
pyroxene, while the upper parts ai'e more perfectly mineral-
ized with serpentine."
n
[The following note was added in a reprint of the paper in
tlie Canadian Naturalist, April, 1865.]
" Since the above was written, thick slices of Eozoon from
(iirenville have been prepared, and submitted to the action of
hydrochloric acid until the carbonate of lime was removed.
The serpentine then remains as a cast of the interior of the
chambers, showing the form of their original sarcode-contents.
The minute tubuli are found also to have been filled with a
substance insoluble in the acid, so that casts of these also
lomain in great perfection, and allow their general distribu-
tion to be much better seen than in the transparent slices
previously prepared. These interesting preparations establish
the following additional structural points : —
" 1. That the whole mass of sarcode throughout the organ-
ism was continuous; the apparently detached secondary
chambers being, as I had previously suspected, connected
with the larger chambers by canals filled with sarcode.
" 2. That some of the irregular portions without lamination
are not fragmentary, but due to the acervuline growth of the
animal ; and that this irregularity has been produced in part
82
THE DAWN OP LIFE.
by the formation of projecting patches of supplementary
skeleton, penetrated by beautiful systems of tubuli. These
groups of tubuli are in some places very regular, and have in
their axes cylinders of compact calcareous matter. Some
parts of the specimens present ai'rangements of this kind as
symmetrical as in any modern Foraminiferal shell.
"3. That all except the very thinnest portions of the walls
of the chambers present traces, more or less distinct, of a
tubular structure.
" 4. These facts place in more strong contrast the structure
of the regularly laminated species from Burgess, which do not
show tubuli, and that of the Grenville specimens, less regularly
laminated and tubulous throughout. I hesitated however to
regard these tTO as distinct species, in consequence of the
intermediate characters presented by specimens from the
Calumet, which are regularly laminated like those of Burgess,
and tubulous like those of Grenville. It is possible that in
the Burgess specimens, tubuli, originally present, have been
obliterated, and in organisms of this grade, more or lesw
altered by the processes of fossilisation, large series of speci-
mens should be compared before attempting to establish
specific distinctions."
(B.) Original Description of the Specimens added by
Dr. Carpenter to the above — in a Letter to
Sir W. E. Logan.
I Journal of Geological Society, February, 1865.]
" The careful examination which I have made, in accordance
with the request you were good enough to convey to me from
Dr. Dawson and to second on your own part, with the struc-
ture of the very extraordinary fossil which you have brought
from the Laurentian rocks of Canada,* enables mo most
* The specimens submitted to Dr. Carpenter were tsiken from a
'block of Eozoon rock, obtained in the Petite Nation seigniory, too
late to afford Dr. Dawson an opportunity of examination. They are
from the same horizon as the Grenville specimens.— W. E. L.
((
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In
it
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a
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WHAT 13 EOZOON ?
83
unhesitatingly to confirm the sagacious determination of
Dr. Dawson as to its Rhizopod characters and Fcraminiferal
affinities, and at the same time famishes new evidence of no
small value in support of that determination. In this exami-
nation I have had the advantage of a series of sections of the
fossil much superior to those submitted to Dr. Dawson ; and
also of a large series of decalcified specimens, of which
Dr. Dawson had only the opportunity of seeing a few ex-
amples after his memoir had been written. These last are
peculiarly instructive ; since in consequence of the complete
infiltration of the chambers and canals, originally occupied by
the sarcode-body of the animal, by mineral matter insoluble in
dilute nitric acid, the removal of the calcareous shell brings
into view, not only the internal casts of the chambers, but also
casts of the interior of the * canal system ' of the ' intermediate '
or * supplemental skeleton,* and even casts of the interior of
the very fine parallel tubuli which traverse the proper walls of
the chambers. And, as I have remarked elsewhere,* ' such
casts place before us far more exact representations of the
configuration of the animal body, and of the connections of its
different parts, than we could obtain even from living speci-
mens by dissolving away their shells with acid ; its several
portions being disposed to heap themselves together in a mass
when they lose the support of the calcareous skeleton.'
" The additional opportunities I have thus enjoyed will be
found, I believe, to account so tisfactorily for the differences to
bo observed between Dr. Dawson's account of the Eozoon and
my own. Had I been obliged to form my conclusions respect-
ing its structure only from the specimens submitted to Dr.
Dawson, I should very probably have seen no reason for any
but the most complete accordance with his description : while
if Dr. Dawson had enjoyed the advantage of examining the
entire series of preparations which have come under my
own observation, I feel confident that he would have antici-
pated the corrections and additions which I now offer.
"Although the general plan of growth described by Dr.
Dawson, and exhibited in his photographs of vertical sections of
• Introduction to the Study of the Foraminifera^ p. 10.
It-
m
ii i
84
THE DAWN OF LIFE.
the fossil, is undoubtedly that which is typical of Eozoon, yet
I find that the acervuline mode of growth, also mentioned by
Dr. Dawson, very frequently takes its place in the more
superficial parts, where the chambers, which are arranged in
regular tiers in the laminated portions, are heaped one upon
smother without any regularity, as is particularly well shown
in some decalcified specimens which I have myself prepared
from the slices last put into my hands. I see no indication
that this departure from the normal type of structure has
resulted from an injury; the transition from the regular to
the irregular mode of increase not being abrupt but gradual,
Nor shall I be disposed to regard it as a monstrosity ; since
there are many other Foraminifera in which an originally defi-
nite plan of growth gives place, in a later stage, to a like
acervuline piling-up of chambers.
" In regard to the form and relations of the chambers, I have
little to add to Dr. Dawson's description. The evidence
afforded by their internal casts concurs with that of sections,
in showing that the segments of the sarcode-body, by whose
aggregation each layer was constituted, were but very incom-
pletely divided by shelly partitions ; this incomplete separation
(as Dr. Dawson has pointed out) having its parallel in that of
the secondary chambers in Carpenteria. But I have occasionally
met with instances in which the separation of the chambers
lias been as complete as it is in Foraminifera generally ; and
the communication between hem is then established by seve-
lal narrow passages exactly corresponding with those which 1
have described and figured in Cycloclypeus.*
" The mode in which each successive layer originates from
the one which had preceded it, is a question to which my atten-
tion has been a good deal directed ; but I do not as yet feel
confident that I have been able to elucidate it completely.
There is certainly no regular system of apertures for the
passage of stolons giving origin to new segments, such as are
found in all ordinary Polythalamous Foraminifera, whether
their type of growth be rectilinear, spiral, or cyclical; and I
am disposed to believe that wliere one layer is separated from
• Op. cit., p. 294.
WHAT IS EOZOON
80
another by nothing else than the proper walls of the chambers,
— which, as I shall presently show, are traversed by multi-
tudes of minute tubuli giving passage to pseudopodia, — the
coalescence of these pseudopodia on the external surface would
suffice to lay the foundation of a new layer of sarcodic seg-
ments. But where an intermediate or supplemental skeleton,
consisting of a thick layer of solid calcareous shell, has been
deposited between two successive layers, it is obvious that
the animal body contained in the lower layer of chambers
must be completely cut off from that which occupies the
upper, unless some special provision exist for their mutual
communication. Such a provision I believe to have been
made by the extension of bands of sarcode, through canals left
in the intermediate skeleton, from the lower to the upper tier
of chambers. For in such sections as happen to have tra-
versed thick deposits of the intermediate skeleton, there are
generally found passages distinguished from those of the
ordinary canal-system by their broad flat form, their great
transverse diameter, and their non-ramification. One of these
passages I have distinctly traced to a chamber, with the cavity
of which it communicated through two or three apertures in
its proper wall ; and I think it likely that I should have been
able to trace it at its other extremity into a chamber of the
superjacent tier, had not the plane of the section passed out of
its course. Eiband-like casts of these passages are often to
be seen in decalcified specimens, traversing the void spaces
left by the removal of the thickest layers of the intermediate
skeleton.
" But the organization of a new layer seems to have not un-
frequently taken place in a much more considerable extension
of the earcode-body of the pre-formed layer; which either
folded back its margin over the surface already consolidated,
in a manner somewhat like that in which the mantle of a
Cyproea doubles back to deposit the final surface-layer of its
shell, or sent upwards wall-like laraellas, sometimes of very
limited extent, but not unfrequently of considerable length,
which, after traversing the substance of the shell, i'ke trap-
dykes in a bed of sandstone, spread themselves out over itd
i !i'
86
THE DAWN OF LIFE,
surface. Such, at least, are the only interpretations I can put
upon the appearances presented by decalcified specimens.
For on the one hand, it is frequently to be observed that two
bands of serpentine (or other infiltrated mineral), which repre-
sent two layers of the original sarcode-body of the animal,
approximate ♦;o each other in some part of their course, and
come into complete continuity ; so that the upper layer would
seem at that part to have had its origin in the lower. Again,
even where these bands are most widely separated, we find
that they are commonly hold together by vertical lamellaB of
the same material, sometimes forming mere tongues, but often
running to a considerable length. That these lamellaD have
not been formed by mineral infiltration into accidental fissures
in the shell, but represent corresponding extensions of the
sarcode-body, seems to me to be indicated not merely by the
characters of their surface, but also by the fact that portions
of the canal-system may be occasionally traced into con-
nection with them.
"Although Dr. Dawson has noticed that some parts of the
sections which he examined present the fine tubulation charac-
teristic of the shells of the Nummuline Foraminifera, he does
not seem to have recognised the fact, which the sections
placed in my hands have enabled me most satisfactorily to
determine, — that the proper walls of the chambers every-
where present the fine tubulation of the Nummuline shell ; a
point of the highest importance in the determination of the
affinities of Eozoon. This tubulation, although not seen with
the clearness with which it is to be discerned in recent exam-
ples of the Nummuline type, is here far better displayed than
it is in the majority of fossil Nummulites, in which the tubuli
have been filled up by the infiltration of calcareous matter,
rendering the shell-substance nearly homogeneous. In Eozoon
these tubuli have been filled up by the infiltration of a mineral
different from that of which the shell is composed, and there-
fore not coalescing with it; and the tubular structure is con-
sequently much more satisfactorily distinguishable. In de-
calcified specimens, the free margins of the casts of the
chambers are often seen to be bordered with a delicate white
WHAT IS EOZOON
87
glistening fringe ; and when this fringe is examined with a
sufficient magnifying power, it is seen to be made up of a
multitude of extremely delicate aciculi, standing side by side
like the fibres of asbestos. These, it is obvious, are the inter-
nal casts of the fine tubuli which perforated the proper wall of
the chambers, passing directly from its inner to its outer
surface; and their presence in this situation affords the most
satisfactory confirmation of the evidence of that tubulation
afforded by thin sections of the shell- wall.
" The successive layers, each having its own proper wall, are
often superposed one upon another without the intervention of
any supplemental or intermediate skeleton such as presents
itself in all the more massive forms of the Nummuline series;
but a deposit of this form of shell-substance, readily dis-
tinguishable by its homogeneousness from the finely tubular
shell immediately investing the segments of the sarcode-body,
is the source of the great thickening which the calcareous
zones often present in vertical sections of Eozoon. The pre-
sence of this intermediate skeleton has been correctly indi-
cated by Dr. Dawson ; but he does not seem to have clearly
differentiated it from the proper wall of the chambers. All
the tubuli which he has described belong to that canal system
which, as I have shown,* is limited in its distribution to the
intermediate skeleton, and is expressly designed to supply a
channel for its nutrition and augmentation. Of this canal
i-^ystem, which presents most remarkable varieties in dimen-
sions and distribution, we learn more from the casts presented
by decalcified specimens, than from sections, which only
exhibit such parts of it as their plane may happen to traverse.
Illustrations from both sources, giving a more complete
representation of it than Dr. Dawson's figures afford, have
been prepared from the additional specimens placed in my
hands.
*• It does not appear to me that the canal system takes its
origin directly from the cavity of the chambers. On the con-
trary, I believe that, as in Calcarina (which Dr. Dawson has
correctly referred to as presenting the nearest parallel to it
* Op. cif. , pp. 50, 51.
8-8
THE DAWN OF LIFE.
among recent Foraminifera), thoy oiiglnato in lacunar spacca
on the outside of the proper walls of the chambers, into which
the tubuli of those walls open externally ; and that the exten-
sions of the sareode-body which occupied thorn wee formed
by the coalescence of the pseudopodia issuing from those
tubuli.*
"It seems to me worthy of special notice, that the canrd
system, wherever displayed in transparent sections, is dis-
tinguished by a yellowish brown coloration, so exactly resem-
bling that which I have observed in the canal system of recent
Foraminifera (as Polystomella and Calcarina) in which there
were remains of the sarcode-body, that I cannot but believe
the infiltrating mineral to have been dyed by the renains of
sarcode still existing in the canals of Eozoon at the time of its
consolidation. If this be the case, the preservation of this
colour seems to indicate that no considerable metamorphio
action has been exerted upon the rock in which this lossil
occurs. And I should draw the same inference from the fact
that the organic structure of the shell is in many instances
even more completely preserved than it usually is in the
Nummulites and other Foraminifera of the Nummulitic lime-
stone of the early Tertiaries.
" To sum up, — That the Eozoon finds its proper place in the
Foraminifera! series, I conceive to be conclusively proved by
its accordance with the great types of that series, in all the
essential characters of organization ; — namely, the structure of
the shell forming the proper wall of the chambers, in which it
agrees precisely with Numnulina and its allies; the presence
of an intermediate skeleton a ad an elaborate canal system, the
disposition of which reminds us most of Calcarina; a mode of
communication of the chambers when they are most com-
pletely separated, which has its exact parallel in Cycloclypeus ;
and an ordinary want of completeness of separation between
the chambers, corresponding with that which is characteristic
of Carpenteria.
" There is t +;her group of the animal kingdom to which
Eozoon presents the slightest structural resemblance; and to
* Op. cit, p. 221.
WHAT IS EOZOON
89
the suggestion that it may have been of kin to Nullipore, I
can offer the most distinct negative reply, having many years
ago carefully studied the structure of that stony Alga, with
which that of Eozoon has nothing whatever in common.
"The objections which not unnaturally occur to those familiar
with only the ordinary forms of Foraminifera, as to the admis-
sion of Eozoon into the series, do not appear to me of any
force. These have reference in the first place to the great si::*'.
of the organism ; and in the second, to its exceptional mode of
growth.
" 1. It must be borne in mind that all the Foraminifera nor-
mally increase by the continuous gemmation of new segments
from those previously formed; and that wo have, in the
existing types, the greatest diversities in the extent to which
this gemmation may proceed. Thus in the Globigerinas,
whose shells cover to an unknown thickness the sea bottom of
all that portion of the Atlantic Ocean which is traversed by
the Gulf Stream, only eight or ten segments are ordinarily
produced by continuous gemmation ; and if new segments aio
developed from the last of these, they detach themselves so as
to lay the foundation of independent Globigei ina3. On the
other hand in Cycloclypeus, which is a discoidal structure
attaining two and a quarter inches in diameter, the number of
segments formed by continuous gemmation must be many
thousand. Ag-ain, the Receptaculites of the Canadian Silurian
rocks, shown by Mr. Salter's drawings* to be a gigantic
Orbitolite, attains a diameter of twelve inches ; and if thi'S
were to increase by vertical as well as by horizontal gemma-
tion (after the manner of Tinoporus or Orbitoides) so that one
discoidal layer would be piled on anothei', it would form a
mass equalling Eozoon in its ordinary dimensions. To say,
therefore, that Eozoon cannot belong to the Foraminifera on
account of its gigantic size, is much as if a botanist who had
only studied plants and shrubs were to refuse to admit a tree
into the same category, llie very same eontimious gemma-
tion which has produced an Eozoon would produce an equal
mass of independent Globigerinae, if after eight or ten repeti-
* First Deeade of Canadian Fossil!^, pi. x.
00
THE DAWN OF LIFE.
tions of the process, the new segments were to detach them-
selves.
" It is to be remembered, moreover, that the largest masses of
sponges are formed by continuous gemmation from an original
Rhizopod sogrcont; and that there is no a priori reason why
a Foraminiferal organism should not attain the same dimen-
sions as a Poriferal one, — the intimate relationship of the two
groups, notwithstanding the difference between their skele-
tons, being unquestionable.
" 2. The difficulty arising from the zoophytic plan of growth
of Fozoon is at once disposed of by the fact that we have in
the recent Polytrema (as I have shown, ojo. cit., p. 235) an
organism nearly allied in all essential points of structure
to Rotalia, yet no less aberrant in its plan of growth, having
been ranked by Lamarck among the Millepores. And it
appears to me that Eozoon takes its place quite as naturally in
the Nummuline series as Polytrema in the Rotaline. As we
are led from the typical Rotalia, through the less regular
Planorbulina, to Tinoporus, in which the chambers are piled
up vertically, as well as multiplied horizontally, and thence
pass by an easy gradation to Polytrema, in which all regularity
of external form is lost; so may we pass from the typical
Operculina or Nummulina, through Heterostegina and Cyclo-
clypeus to Orbitoides, in which, as in Tinoporus, the chambers
multiply both by horizontal and by vertical gemmation ; and
from Orbitoides to Eozoon the transition is scarcely more
abrupt than from Tinoporus to Polytrema,
"The general acceptance, by the most competent judges, of
my views respecting the primary value of the characters fur-
nished by the intimate structure of the shell, and the very
subordinate value of plan of growth, in the determination of
the affinities of Foraminifera, renders it unnecessary that I
should dwell further on my reasons for unhesitatingly affirm-
ing the Nummuline affinities of Eozoon from the micrascopic
appearances presented by the proper wall of its chambers,
notwithstanding its very abberant peculiarities ; and I cannot
but feel it to be a feature of peculiar interest in geological
inquiry, that the true relations of by far the earliest fossil yet
WHAT IS EOZOON ?
91
known should be determinable by the comparison of a portion
which the smallest pin's head would cover, with organisms at
present existing."
(C) Note on Specimens from Long Lake and Went worth.
[Journal of Geological Society, August, 1867-]
" Specimens from Long Lake, in the collection of the Geo-
logical Survey of Canada, exhibit white crystalline limestone
with light green compact or septariiform* serpentine, and
much resemble some of the serpentine limestones of Grenville.
Under the microscope the calcareous matter presents a deli-
cate areolated appearance, without lamination ; but it is not an
example of acervuline Eozoon, but rather of fragments of such
a structure, confusedly aggregated together, and having the
interstices and cell-cavities filled with serpentine. I have not
found in any of these fragments a canal system similar to that
of Eozoon Canadense, though there are casts of large stolons,
and, under a high power, the calcareous matter shows in many
places the peculiar granular or cellular appearance which is
one of the characters of the supplemental skeleton of thnt
species. In a few places a tubulated cell-wall is preserved,
wioh structure similar to that of Eozoou Canadense.
" Specimens of Laurentian limestone from Wentworth, in the
collection of the Geological Survey, exhibit many rounded sili-
cious bodies, some of which areapparently grains of sand, or small
pebbles ; but others, especially when freed from the calcareous
matter by a dilute acid, appear as rounded bodies, with rough
surfaces, either separate or aggregated in lines or groups, and
having minute vermicular processes projecting from their sur-
faces. At first sight these suggest the idea of spicules ; but I
think it on the whole more likely that they are casts of cavities
and tubes belonging to some calcareous Foraminiferal organ-
ism which has disappeared. Similar bodies, found in the
limestone of Bavaria, have been described by Giimbel, who
interprets them in the same waj'. They may also be com-
* I use the term '* eeptariiform " to denote the cuddled appearance
so often presented by the Laurentian serpentine.
!
W ' V.I »J I
* > .
92
THE DAWN OP LIFE.
pared with the silicious bodies mentioned in a former paper as
occurring in the loganite filling the chambers of specimens of
Eozoon from Burgess."
These specimens will be more fully referred to under
Chapter VI.
(D.) AoDiTioNAJi Structural Facts.
I may mention here a peculiar and interesting structure
which has been detected in one of my specimens while these
sheets were passing through the press. It is an abnormal
thickening of the calcareous wall, extending across several
layers, and perforated with large parallel cylindrical canals,
filled with dolomite, and running in the direction of the
laminoB ; tbe intervening calcite being traversed by a very fine
and delicate canal system. It makes a nearer approach to
some of the Stromatoporoa mentioned in. Chapter VI. than any
other Laurentian structure hitherto observed, and may be
either an abnormal growth of Eozoon, consequent on some
injury, or a parasitic mass of some Stromatoporoid organism
overgrown by the laminsa of the fossil. The structure of the
dolomite in this specimen indicates that it first lined the
canals, and afterward filled them ; an appearance which I have
also observed recently in the larger canals filled with serpi n-
tine (Plate YIII., fig. 5). The cut below is an attempt, only
partially successful, to show the Amoeba-like appearance,
when magnified, of the casts of the chambers of Eozoon, as
seen on the decalcified surface of a specimen broken, parallel
to the laminae.
Fia. 21a.
Plate V.
Nature-print of Eozoon, showing laminateil, accrvullne, and fia^mental
portions.
This is printed from an electrotype taken from an etciied slab of Eozoon, and
not touched mth a graver except to remedy some accidental Haws in the plate.
The diagonal vvliite line marks the course of a calcite vein.
'CHAPTER V.
THE PRESERVATION OF EOZOON.
Pkrhaps nothing excites more scopticisra as to this
ancieat fossil than the prejudice existing among
geologists that no organism can be preserved in rocks
so highly metamorphic as those of the Laurentian
series. I call tliis a prejudice, because any one who
makes the microscopic structure of rocks and fossils
a special study, soon learns that fossils undergo the
most remarkable and complete chemical changes
without losing their minute structure, and that cal-
careous rocks if once fossiliferous are hardly ever
so much altered as to lose all trace of the organisms
which they contained, while it is a most common occur-
rence to find highly crystalline rocks of this kind
abounding in fossils preserved as to their minute
structure.
Let us, however, look at the precise conditions
under which this takes place.
When calcareous fossils of irregular surface and
porous or cellular texture, such as Eozoon was or
corals were and are, become imbedded in clay, marl,
or other soft sediment, they can be washed out and
recovered in a condition similar to that of recent
94
THE DAWN OF LIFE.
specimens, except that their pores or cells if open
may be filled with the material of the matrix, or if
not so open that they can be thus filled, they may be
more or less incrusted with mineral deposits intro-
duced by water, or may even be completely filled up
in this way. But if such fossils are contained in
hard rocks, they usually fail, when these are broken,
to show their External surfaces, and, breaking across
with the containing rock, they exhibit their internal
structure merely, — and this more or less distinctly,
according to the manner in which their cells or cavi-
ties have been filled. Here the microscope becomes
of essential service, especially when the structures
are minute. A fragment of fossil wood which to the
naked eye is nothing but a dark stone, or a coral
which is merely a piece of gray or coloured marble,
or a specimen of common crystalline limestone made
up originally of coral fragments, presents, when sliced
and magnified, the most perfect and beautiful structure.
In such cases it will be found that ordinarily the
original substanco of the fossil remains, in a more
or less altered state. Wood may be represented by
dark lines of coaly matter, or coral by its white or
transparent calcareous laminae ; while the material
which has been introduced and which fills the cavities
may so differ in colour, transparency, or crystalline
structure, as to act differently on light, and so reveal
the structure. These fiPings are very curious. Some-
times they are mere earthy or muddy matter. Some-
times they are pure and transparent and crystalline.
THE PRESERVATION OF EOZOOX.
95
Often they are stained with oxide of iron or coaly
matter. They may consist of carbonate of lime, silica
or silicates, sulphate of baryta, oxides of iron, car-
bonate of iron, iron pyrite, or sulphides of copper or
lead, all of which are common materials. They are
sometimes so complicated that I have seen even the
minute cells of woody siructures, each with several
bands of differently coloured materials deposited in
succession, like the coats of an onyx agate.
A further stage of mineralization occurs when the
substance of the organism is altogether removed and
replaced by foreign matter, either little by little, or
by being entirely dissolved or decomposed, leaving
a cavity to be filled by infiltration. In this state
are some silicified woods, and those corals which have
been not filled with but converted into silica, and can
thus sometimes be obtained entire and perfect by the
solution in an acid of the containing limestone, or by
its removal in weathering. In this state are the beauti-
ful silicified corals obtained from the corniferous lime-
stone of Lake Erie. It may be well to present to
the eye these different stages of fossilization. I have
attempted to do this in fig. 22, taking a tabulate
coral of the genus Favosites for an example, and
supposing the materials employed to be calcite and
silica. Precisely the same illustration would apply
to a piece of wood, except that the cell-wall would
be carbonaceous matter instead of carbonate of lime.
In this figure the dotted parts represent carbonate of
lime, tho diagonally shaded parts silica or a silicate.
"II
m
TUE DAWN OF LIFE,
Thus we liave, in the natural state, tlie walls of car-
bonate of lime and the cavities empty. When fossil-
ized the cavities may be merely filled with carbonate
of lime, or they may be filled with silica ^ or the walls
themselves may be replaced by silica and the cavities
may remain filled with carbonate of lime; or both
the walls and cavities may be represented by or filled
with silica or silicates. The ordinary specimens of
Eozoon are in the third of tliese stages, though some
;i I
» 1 1 ' 1 1
•tti
»r7r.ri
Si
^••»»^
m.
■m,
I til
"S
^^^
m
'#
Wi
Fig. 22. Diagram showinfj different States of Fossilization of a Cell
of a Tabulate Coral.
a.) Natural condition — walls calcito, cell empty, (b.) Walls calcite, cell filled
with the same, (c.) Walls calcite, cell filled with silica or silicate, (d.) Walls
silicifled, cell filled with calcite. (e.) Walls silicifled, cell filled with silica
or silicate.
exist in the second, and I have reason to believe that
some have reached to the fifth. I have not met with
any in the fourth stage, though this is not uncommon
in Silurian and Devonian fossils.
With regard to the calcareous organisms v/ith which
we have now to do, when these are imbedded in pure
limestone and filled with tlie same, so that the whole
rock, fossils and all, is identical in composition, and
when metamorphic action has caused the whole to
become crystalline, and perhaps removed the remains
of carbonaceous matter, it may be very difficult to
THE PRESERVATION OP EOZOON.
97
detect any traces of fossils. But even in this case
careful management of light may reveal indications
of structure, as in some specimens of Eozoon described
by the writer and Dr. Carpenter. In many cases,
however, even where the limestones have become
perfectly crystalline, and the cleavage planes cut freely
across the fossils, these exhibit their forms and minute
structure in great perfection. This is the case in
many of the Lower Silurian limestones of Canada, as
I have elsewhere shown.* The gray crystalline
Trenton limestone of Montreal, used as a building
stone, is an excellent illustration of this. To the
naked eye it is a gray marble composed of cleavable
crystals ; but when examined in thin slices, it shows
its organic fragments in the greatest perfection, and
all the minute structures are perfectly marked out
by delicate carbonaceous lines. The only exception
in this limestone is in the case of the Crinoids, in
which the cellular structure is filled with transparent
calc-spar, perfectly identical with the original solid
matter, so that they appear solid and homogeneous,
and can be recognised only by their external forms.
The specimen represented in fig. 23, is a mass of
Corals, Bryozoa, and Crinoids, and shows these under
a low power, as represented in the figure ; but to the
naked eye it is merely a gray crystalline limestone.
The specimen represented in fig. 24 shows the
Laurentian Eozoon in a similar state of preservation.
* Canadian Naturalist, 1859 ; Microscopic Structure of Cauadiau
Limestones.
B
n
p.
98
THE DAWN OP LIFE.
It is from a sketcli by Dr. Carpenter, and shows the
delicate canals partly filled with calcite as clear and
Fig. 23. Slice of Crystalline Loicer Silurian Limestone ; shoicing
Crinoids, Bryozoa, and Corals in fragments.
Fig. 24. Wall of Eozoon penetrated with Canals. The nnshadcd
portions filled with Calcite, {After Carpenter.)
colourless as that of the shell itself, and distinguish-
able only by careful management of the light.
In the case of recent and fossil Foraminifers, th«^se
— when not so little mineralized that their chambers
THE PRESERVATION OP EOZOON.
99
are empty, or only partially filled, which is sometimes
the case even with Eocene Nummulites and Cretaceous
forms of smaller size, — are very frequently filled solid
with calcareous matter, and as Dr. Carpenter well
remarks, even well preserved Tertiary Nummulites
in this state often fail greatly in showing their struc-
tures, though in the same condition they occasionally
show these in great perfection. Among the finest
I have seen are specimens from the Mount of Olives
(fig. 19), and Dr. Carpenter mentions as equally good
those of the London clay of Bracklesham. But in
no condition do modern Foraminifera or those of the
Tertiary and Mesozoic rocks appear in greater perfec-
tion than when filled with the hydrous silicate of iron
and potash called glauconite, and which gives by
the abundance of its little bottle-green concretions
the name of " green- sand " to formations of this age
both in Europe and America. In some beds of green-
sand every grain seems to have been moulded into
the interior of a microscopic shell, and has retained
its form after the frail envelope has been removed.
In some cases the glauconite has not only filled the
chambers but has penetrated the fine tubulation, and
when the shell is removed, either naturally or by the
action of an acid, these project in minute needles or
bundles of threads from the surface of the cast. It
is in the warmer seas, and especially in the bed of
the ^gean and of the Gulf Stream, that such specimens
are now most usually found. If we ask why this
mineral glauconite should be associated with Foramini-
100
THE DAWN OF LIFE.
feral shells^ the answer is that they are both products
of one kind of locality. The same sea bottoms iu
which Foraminifera most abound are also those iu
which for some unknown chemical reason glauconite
is deposited. Hence no doubt the association of this
mineral with the great Foraminiferal formation of the
chalk. It is indeed by no means unlikely that the
selection by these creatures of the pure carbonate of
lime from the sea-water or its minute plants, may bo
the means of setting free the silica, iron, and potash,
in a state suitable for their combination. Similar
silicates are found associated with marine limestones,
as far back as the Silurian age ; and Dr. Sterry Hunt,
than whom no one can be a better authority on chemi-
cal geology, has argued on chemical grounds that
the occurrence of serpentine with the remains of
Eozoon is an association of the same character.
However this may be, the infiltration of the pores
of Eozoon with serpentine and other silicates has
evidently been one main means of the preservation of
its structure. Vfhen so infiltrated no metamorphisni
short of the complete fusion of the containing rock
could obliterate the minutest points of structure ; and
that such fusion has not occurred, the preservation in
the Laurentian rocks of the most delicate lamination
of the beds shows conclusively; while, as already
stated, it can be shown that the alteration which has
occurred might have taken place at a temperature far
short of that necessary to fuse limestone. Thus
has it happened that these most ancient fossils have
THE PRESERVATION OP EOZOON.
101
been handed down to our time in a state of preserva-
tion comparable, as Dr. Carpenter states, to that of
the best preserved fossil Foraminifera from the more
recent formations that have come under his observa-
tion in the course of all his long experience.
Let us now look more minutely at the nature of
the typical specimens of Eozoon as originally observed
and described, and then turn to those preserved in
other ways, or more or less destroyed and defaced.
Taking a polished specimen from Petite Nation, like
that delineated in Plate V., we find the shell repre-
sented by white limestone, and the chambers by light
green serpentine. By acting on the surface with a
dilute acid we etch out the calcareous part, leaving
a cast in serpentine of the cavities occupied by the soft
parts ; and when this is done in polished slices these
may be made to print their own characters on paper,
as has actually been done in the case of Plate V., which
is an electrotype taken from an actual specimen, and
shows both the laminated and acervuline parts of
the fossil. If the process of decalcification has been
carefully executed, we find in the excavated spaces
delicate ramifying processes of opaque serpentine or
transparent dolomite, which were originally imbedded
in the calcareous substance, and which are often of
extreme fineness and complexity. (Plate VI. and fig.
10.) These are casts of the canals which traversed
the shell when still inhabited by the animal. In some
well preserved specimens we find the original cell-
wall represented by a delicate white film, which under
102
THE DAWN OF UPE.
the microscope sliows minute needle-like parallel pro-
cesses representing its still finer tubuli. It is evident
that to have filled these tubuli the serpentine must
have been introduced in a state of actual solution,
and must have carried with it no foreign impurities.
Consequently we find that in the chambers themselves
the serpentine is pure ; and if we examine it under
polarized light, we see that it presents a singularly
curdled or irregularly laminated appearance, which I
have designated under the name septariiform, as if
it had an imperfectly crystalline structure, and had
been deposited in irregular lamina?, beginning at the
sides of the chambers, and filling them toward the
middle, and had afterward been cracked by shrinkage,
and the cracks filled with a second deposit of serpen-
tine. Now, serpentine is a hydrous silicate of mag-
nesia, and all that we need to suppose is that in the
deposits of the Laurentian sea magnesia was present
instead of iron and potash, and we can understand
that the Laurentian fossil has been petrified by infil-
tration with serpentine, as more modern Foraminifera
have been with glauconite, which, though it usually
has little magnesia, often has a considerable percent-
age of alumina. Further, in specimens of Eozoon
from Burgess, the filling mineral is loganite, a com-
pound of silica, alumina, magnesia and iron, with
water, and in certain Silurian limestones from New
Brunswick and Wales, in which the delicate micro-
scopic pores of the skeletons of stalked star-fishes or
Crinoids have been filled with mineral deposits, so
THE PEESERVATION OF EOZOON.
103
that when decalcified these are most beautifully repre-
sented by their casts, Dr. Hunt has proved the filUng
mineral to be a silicate of alumina, iron, magnesia
and potash, intermediate between serpentine and
glauconite. We have, therefore, ample warrant for
adhering to Dr. Hunt's conclusion that the Lauren-
Fio. 25. Joint of a Crinoid, having its pores injected with a
Hydrous Silicate.
Upper Silurian Limestone, Polo HLll, New Brunawick. Maguified 25 diameters.
tian serpentine was deposited under conditions similar
to those of the modern green-sand. Indeed, indepen-
dently of Eozoon, it is impossible that any geologist
who has studied the manner in which this mineral
is associated with the Laurentian limestones could
believe it to have been formed in any other way. Nor
r'^'^ : mr
I"
Hill
lii,:
in
.it !•
M>; I
104
THE DAWN OF LIFE.
need wg be astonished at the fineness of the infil-
tration by which these minute tubes, perhaps tq^o of
an inch in diameter, are filled with mineral matter.
The micro-geologist well knows how, in more modern
deposits, the finest pores of fossils are filled, and that
mineral matter in solution can penetrate the smallest
openings that the microscope can detect. Wherever tho
fluids of the living body can penetrate, there also mineral
Via. 20. Shell from a Silitrian Limestone, Wales ; its cavity filled
with a Hydrous Silicate.
Mngrnifictl 25 diameters.
substances can be carried, and this natural injection,
efiected under great pleasure and with the advantage
of ample time, can surpass any of the feats of the
anatomical manipulator. Fig. 25 represents a micro-
scopic joint of a Crinoid from the Upper Silurian of
New Brunswick, injected with the hydrous silicate
already referred to, and fig. 26 shows a microscopic
THE rRESEBVATION OF EOZOON.
105
chambered or spiral shell, from a Welsli Silurian
limestone, with its cavities filled with a similar sub-
stance.
It is only necessary to refer to the attempts which
have been mado to explain by merely mineral doposits
tho occurrence of tho serpentine in the canals and
chambers of Eozoon, and its presenting tho form it
does, to seo that this is the case. Prof. Rowney, for
example, to avoid tho force of tho argument from the
canal system, is constrained to imagine that the whole
mass has at one time been serpentine, and that this has
been partially wa. hed away, and replaced by calcite. If
so, whence the deposition of the supposed mass of ser-
pentine, which has to be accounted for in this way as
well as in tho other ? How did it happen to be eroded
into so regular chambers, leaving intermediate floors
and partitions. And, more wonderful still, how did
the regular dendritic bundles, so delicate that they aro
removed by a breath, remain perfect, and endure until
they were imbedded in calcareous spar ? Further, how
does it happen that in some specimens serpentine and
pyroxene seem to have encroached upon the structure,
as if they and not calcite were the eroding minerals ?
How any one who has looked at the structures can for
a moment imagine such a possibility, it is difficult to
understand. If we could suppose the serpentine to have
been originally deposited as a cellular or laminated mass,
and its cavities filled with calcite in a gelatinous or semi-
fluid state, we might suppose the fine processes of ser-
pentine to have grown outward into these cavities in
>
y
Y,
106
THE DAWN OF LIFE.
the mass, as fibres of oxide of iron or manganese have
grown in the silica of moss-agate ; but this theory
would be encompassed with nearly as great mechanical
and chemical difficulties. The only rational view that
any one can take of the process is, that the calcareous
matter was the original substance, and that it had
delicate tubes traversing it which became injected with
serpentine. The same explanation, and no other, will
suffice for those delicate cell- walls, peneiiated by in-
numerable threads of serpentine, which must have been
injected into pores. It is true that there are in some
of the specimens cracks filled with fibrous serpentine or
Fig. 27. Diagram shoiolng the different appearances of the cell-ivall
of Eozoon and of a vein of Chrysotile, when highly magnified.
chrysotile, but these traverse the mass in irregular
directions, and they consist of closely packed angular
prisms, instead of a matrix of limestone penetrated by
cylindrical threads of serpentine. (Fig. 27.) Here I
must once for all protest against the tendency of some
opponents of Eozoon to confound these structures and
the canal system of Eozoon with the acicular crystals,
and dendritic or coralloidal forms, observed in some
minerals. It is easy to make such comparisons appear
plausible to the uninitiated, but practised observers
cannot be so deceived, the difierences are too marked
THE PRESERVATION OP EOZOON.
107
and Gssential. In illustration of this, I may refer to the
highly magnified canals in figs. 28 and 29. Further,
it is evident from the examination of the specimens,
that the chrysotile veins, penetrating as they often do
FxG. 23. C.i8ts of Canals of Eozoon in Serpentine, decalcified and
highly magnified.
^'^<;^-
Fig. 29. Canals of Eozoon.
HigWy magnified.
diagonally or transversely across both chambers and
walls, must have originated subsequently to the origin
and hardening of the rock and its fossils, and result
from aqueous deposition of fibrous serpentine in cracks
which traverse alike the fossils and their matrix. In
;:^i|||
'irfVJ
Mill :, >
108
THE DAWN OF LIFE.
specimens now before me, nothing can be more plain
than this entire independence of the shining silky
veins of fibrous serpentine, and the fact of their
having been formed subsequently to the fossilization of
the Eozoon ; since they can be seen to run across the
lamination, and to branch off irregularly in lines alto-
gether distinct from the structure. This, while it
shows that these veins have no connection with the
fossil, shows also that the latter was an original
ingredient of the beds when deposited, and not a
product of subsequent concretionary action.
Taking the specimens preserved by serpentine as
typical, we now turn to certain other and, in some
respects, less characteristic specimens, which are never-
theless very instructive. At the Calumet some of the
masses are partly filled with serpentine and partly with
white pyroxene, an anhydrous silicate of lime and
magnesia. The two minerals can readily be dis-
tinguished when viewed with polarized light ; and in
some slices I have seen part of a chamber or group of
canals filled with serpentine and part with pyroxene.
In this case the pyroxene or the materials which now
compose it, must have been introduced by infiltration,
as well as the serpentine. This is the more remarkable
as pyroxene is most usually found as an ingredient of
igneous rocks; but Dr. Hunt has shown that in the
Laurentian limestones and also in veins traversing
them, it occurs under conditions which imply its depo-
sition from water, either cold or warm. Giimbel
remarks on this : — " Hunt^ in a very ingenious
THE PRESERVATION OF EOZOON.
109
manner, compares this formation and deposition of
serjDentine, pyroxene, and loganite, with that of glau-
conite, whose formation has gone on uninterruptedly
from the Silurian to the Tertiary period, and is even
now taking place in the depths of the sea ; it being
well known that Ehrenberg and others have already
shown that many of the grains of glauconite are casts
of the interior of foraminiferal shells. In the light of
this comparison, the notion that the serpentine and
such like minerals of the primitive limestones have
been formed, in a similar manner, in the chambers of
Eozoic Foraminifera, loses any traces of improbability
which it might at first seem to possess."
In many parts of the skeleton of Eozoon, and even
in the best infiltrated serpentine specimens, there are
portions of the cell-wall and canal system which have
been filled with calcareous spar or with dolomite, so
similar to the skeleton that it can be detected only
under the most favourable lights and with great care.
(Fig. 24, su'iira.) The same phenomena may be ob-
served in joints of Crinoids from the Palaeozoic rocks,
and they constitute proofs of organic origin even more
irrefragable than the filling with serpentine. Dr.
Carpenter has recently, in replying to the objections of
Mr. Carter, made excellent use of this feature of the
preservation of Eozoon. It is further to be remarked
that in all the specimens of true Eozoon, as well as in
many other calcareous fossils preserved in ancient
rocks, the calcareous matter, even when its minute
structures are not preserved or are obscured, presents
no
THE DAWN OP LIFE.
:h 1 :
iil
a minutely granular or curdled appearance, arising no
doubt from the original presence of organic matter,
and not recognised in purely inorganic calcito.
Another style of these remarkable fossils is tha^ :
the Burgess specimens. In these the walls have been
changed into dolomite or magnesian limestone, and
the canals seem to have been wholly obliterated, so
that only the laminated structure remains. The
material filling the chambers is also an aluminous
silicate named loganite ; and this seems to have been
introduced, not so much in solution, as in the state of
muddy slime, since it contains foreig i bodies, as grains
of sand and little groups of silicious concretions, some
of which are not unlikely casts of the interior of
minute foraminiferal shells contemporary with Eozoon,
and will be noticed in the sequel.
Still another mode of occurrence is presented by a
remarkable specimen from Tudor in Ontario, and from
beds probably on the horizon of the Upper Laurentian
or Huronian.* It occurs in a rock scarcely at all
metamorphic, and the fossil is represented by white
carbonate of lime, while the containing matrix is a
dark-coloured coarse limestone. In this specimen the
material filling the chambers has not penetrated the
canals except in a few places, where thoy appear filled
with dark carbonaceous matter. In mode of preser-
vation these Tudor specimens much resemble the
ordinary fossils of the Silurian rocks. One of the
specimens in the collection of the Geological Survey
* See Note B, Chap. III.
THE PRESERVATION OP EOZOON.
Ill
(fig. 30) presents a clavate form, as if it had been a
detached individual supported on one end at the bottom
of the sea. It shows, as does also the original Calumet
specimen, the septa approaching each other and coal-
escing at the margin of the form, where there were
Fig. 30. Eozoon from Tudor.
Two-thirds natural size, (a.) Tubuli. (b.) Canals. Magnified.
a and b from another specimen.
probably orifices communicating with the exterior.
Other specimens of fragmental Eozoon from the Petite
Nation localities have their canals filled with dolomite,
which probably penetrated them after they were
'■r'''ii
li!:
11)
112
THE DAWN OP LIFE.
broken up anrl imbedded in the rock. I have ascer-
tained with respect to these fragments of Eozoon, that
they occur abundantly in certain layers of the Lauren-
tian limestone, beds of some thickness being in great
part made up of them, and coarse and fine fragments
occur in alternate layers^ like the broken corals in
some Silurian limestones.
Finally, on this part of the subject, careful observa-
tion of many specimens of Laurentian limestone which
present no trace of Eozoon when viewed by the naked
eye, and no evidence of structure when acted on with
acids, are nevertheless organic, and consist of fragments
of Eozoon, and possibly of other organisms, not infil-
trated with silicates, but only with carbonate of lime,
and consequently revealing only obscure indications of
their minute structure. I have satisfied myself of
this by long and patient investigations, which scarcely
admit of any adequate representation, either by words
or figures.
Every worker in those applications of the microscope
to geological specimens which have been termed micro-
geology, is familiar with the fact that crystalline forces
and mechanical movements of material often play the
most fantastic tricks with fossilized organic matter. In
fossil woods, for exomple, we often have the tissues
disorganized, with radiating crystallizations of calcite
and little spherical concretions of quartz, or dissemina-
ted cubes and grains of pyrite, or little veins filled
with sulphate of barium or other minerals. We need
not, therefore, be surprised to find that in the vener-
mw
THE PRESERVATION OF EOZOON.
113
able rocks containing Eozoon, such things occur in the
more highly crystalHne parts of the Hmestones, and
even in some still showing traces of the fossil. We
find many disseminated crystals of magnetite^ pyrite,
spinel, mica, and other minerals, curiously curved
prisms of vermicular mica, bundles of aciculi of tre-
molite and similar substances, veins of calcite and cry-
solite or fibrous serpentine, which often traverse the
best specimens. Where these occur abundantly we
usually find no organic structures remaining, or if
they exist they are in a very defective state of preser-
vation. Even in specimens presenting the lamination
of Eozoon to the naked eye, these crystalline actions
have often destroyed the minute structure ; and I fear
that some microscopists have been victimised by
having under their consideration only specimens in
which the actual characters had been too much de-
faced to be discernible. I must here state that I have
found some of the specimens sold under the name of
Eozoon Canadense by dealers in microscopical objects
to be almost or quite worthless, being destitute of
any good structure, and often merely pieces of Lauren-
tian limestone with serpentine grains only. I fear
that the circulation of such specimens has done much
to cause scepticism as to the Foraminiferal nature of
Eozoon. No mistake can be greater than to suppose
that any and every specimen of Laurentian limestone
must contain Eozoon. More especially have I hitherto
failed to detect traces of it in those carbonaceous or
graphitic limestones which are so very abundant in
I
114
THE DAWN OP LIFE.
Hi iiiii
i!!>
i
the Laurentian country. Perhaps where vegetable
matter was very abundant Eozoon did not thrive, or
on the other hand the growth of Eozoon may have
diminished the quantity of vegetable matter. It is
also to be observed that much compression and distor-
tion have occurred in the beds of Laurentian limestone
and their contained fossils, and also that the specimens
are often broken by faults, some of which are so small
as to appear only on microscopic examination, and to
shift the plates of the fossil just as if they were beds of
rock. This, though it sometimes produces puzzling
appearances, is an evidence that the fossils were hard
and brittle when this faulting took place, and is conse-
quently an additional proof of their extraneous origin.
In some specimens it would seem that the lower and
older part of the fossil had been wholly converted into
serpentine or pyroxene, or had so nearly experienced
this change that only small parts of the calcareous wall
can be recognised. These portions correspond with
fossil woods altogether silicified, not only by the filling
of the cells, but also by the conversion of the walls
into silica. I have specimens which manifestly show
the transition from the ordinary condition of filling
with serpentine to one in which the cell-walls are
represented obscurely by one shade of this mineral
and the cavities by another.
The above considerations as to mode of preservation
of Eozoon concur with those in previous chapters in
showing its oceanic character ; but the ocean of the
Eozoic period may not have been so deep as at
THE PRESERVATION OF EOZOON.
115
present, and its waters were probably warm and well
stocked with mineral matters derived from the newly-
formed land, or from hot springs in its own bottom.
On this point the interesting investigations of Dr.
Hunt with reference to the chemical conditions of the
Silurian seas, allow us to suppose that the Laurentian
ocean may have been much more richly stored, more
especially with salts of lime and magnesia, than that
of subsequent times. Hence the conditions of warmth,
light, and nutriment, required by such gigantic Proto-
zoans would all be present, and hence, also no doubt,
some of the peculiarities of its mineralization.
(A.)
NOTES TO CHAPTER V.
De. Sterry Hunt on the Mineralogy of Eozoon and
THE containing EoCKS.
It was fortunate for the recognition of Eozoon that Dr.
Hunt had, before its discovery, made so thorough researches
into the chemistry of the Laurentian series, and was prepared
to show the chemical possibilities of the preservation of fossils
in these ancient deposits. The following able summary of his
views wail appended to the original description of the fossil in
the Journal of the Geological Society.
" The details of structure have been preserved by the intro-
duction of certain mineral silicates, which have not only filled
up the chambers, cells, and canals left vacant by the disap-
pearance of the animal matter, but have in very many cases
been injected into the tubuli, filling even their smallest rami-
fications. These silicates have thus taken the place of the
original sarcode, while the calcareous septa remain. It will
then be understood that when the replacement of the Eozoon
by silicates is spoken of, this is to be understood of the soft
IIG
THE DAWN OF LIFE.
I III
hiilliii
parts only ; since the calcareous skeleton is preserved, in most
cases, without any alteration. The vacant spaces left by the
decay of the sarcode may be supposed to have been filled by a
process of infiltration, in which the silicates were deposited
from solution in water, like the silica which fills up the pores
of wood in the process of silicification. The replacing sili-
cates, so far as yet observed, are a white pyroxene, a pale green
serpentine, and a dark green alumino-magnesian mineral,
which is allied in composition to chlorite and to pyrosclerite,
and which I have referred to loganite. The calcareous septa
in the last case are found to be dolomitic, but in the other in-
stances are nearly pure carbonate of lime. The relations of
the carbonate and the silicates are well seen in thin sections
under the microscope, especially by polarized light. The
calcite, dolomite, and pyroxene exhibit their crystalline struc-
ture to the unaided eye; and the serpentine and loganite are
also seen to be crystalline when examined with the microscope,
"When portions of the fossil are submitted to the action of an
acid, the carbonate of lime is dissolved, and a coherent mass
of serpentine is obtained, which is a perfect cast of the soft
parts of the Eozoon. The form of the sarcode which filled
the chambers and cells is beautifully shown, as well as the
connecting canals and the groups of tubuli ; these latter are
seen in great perfection upon surfaces from which the carbon-
ate of lime has been partially dissolved. Their preservation
is generally most complete when the replacing mineral is ser-
pentine, although very perfect specimens are sometimes
found in pyroxene. The crystallization of the latter mineral
appears, however, in most cases to have disturbed the calca-
reous septa.
" Serpentine and pyroxene are generally associated in tliese
specimens, as if their disposition had marked difierent stages
of a continuous process. At the Calumet, one specimen of the
fossil exhibits the whole of the sarcode replaced by serpen-
tine ; while, in another one from the same locality, a layer of
pale green translucent serpentine occurs in immediate contact
with the white pyroxene. The calcareous septa in this speci-
men are very thin, and are transverse to the plane of contact
THE PRESERVATION OP EOZOON.
117
of the two minerals ; yet they are seen to traverse both the
pyroxene and the serpentine without any interruption or
change. Some sections exhibit these two minerals filling ad-
jacent cells, or even portions of the same cell, a clear line of
division being visible between them. In the specimens from
Grenville on the other hand, it would seem as if the develop-
ment of the Eozoon (considerable masses of which were re-
placed by pyroxene) had been interrupted, and that a second
growth of the animal, which was replaced by serpentine, had
taken place upon the older masses, filling up their inter-
stices."
[Details of chemical composition are then given.]
'* When examined under the microscope, the loganite which
replaces the Eozoon of Burgess shows traces of cleavage-
lines, which indicate a crystalline structure. The grains of
insoluble matter found in the analysis, chiefly of quartz-sand,
are distinctly seen as foreign bodies imbedded in the mass,
which is moreover marked by lines apparently due to cracks
formed by a shrinking of the dlicate, and subsequently filled
by a further infiltration of the same material. This arrange-
ment resembles on a minute scale that of septaria. Similar
appearances are also observed in the serpentine which replaces
the Eozoon of Grenville, and also in a massive serpentine
from Burgess, resembling this, and enclosing fragments of
the fossil. In both of these specimens also grains of me-
chanical impurities are detected by the microscope ; they are
however, rarer than in the loganite of Burgess.
" From the above facts it may be concluded that the various
silicates which now constitute pyroxene, serpentine, and
loganite were directly deposited in waters in the midst of
which the Eozoon was still growing, or had only recently
perished ; and that these silicates penetrated, enclosed, and
preserved the calcareous structure precisely as carbonate of
lime might have done. The association of the silicates with
the Eozoon is only accidental ; and large quantities of them,
deposited at the same time, include no organic remains. Thus,
for example, there are found associated with the Eozoon lime-
stones of Grenville, massive layers and concretions of pure
Mh
118
THE DAWN OF LIFE,
! !'!
serpentine; and a serpentine from Burgess has already been
mentioned as containing only small broken fragments of tbo
fossil. In like manner large masses of white pyroxene, often
surrounded by serpentine, both of -which are destitute of traces
of organic structure, are found in the limestone at the Calu-
met. In some cases, however, the crystallization of the py-
roxene has given rise to considerable cleavage-planes, and has
thus obliterated the organic structures from masses which,
judging from portions visible here and there, appear to have
been at one time penetrated by the calcareous plates of Eozoon.
Small irregular veins of crystalline calcite, and of serpentine,
are found to traverse such pyroxene masses in the Eozoon
limestone of Grenville.
" It appears that great beds of the Laurentian limestones
are composed of the ruins of the Eozoon. These rocks,
which are white, crystalline, and mingled with pale green ser-
pentine, are similar in aspect to many of the so-called primary
limestones of other regions. In most cases the limestones
are non-magnesian, but one of them from Grenville was found
to be dolomitic. The accompanying strata often present finely
crystallized pyroxene, hornblende, phlogopite, apatite, and
other minerals. These observations bring the formation of
silicious minerals face to face with life, and show that their
generation was not incompatible with the contemporaneous
existence and the preservation of organic forms. They con-
firm, moreover, the view which I some years since put forward,
that these silicated minerals have been formed, not by subse-
quent metamorphism in deeply buried sediments, but by re-
actions going on at the earth's surface.* In support of this
view, I have elsewhere referred to the deposition of silicates
of lime, magnesia, and iron from natural waters, to the great
beds of sepiolite in the unaltered Tertiary strata of Europe ;
to the contemporaneous formation of neolite (an alumino-
magnesian silicate related to loganite and chlorite in composi-
tion) ; and to glauconite, which occurs not only in Secondary,
Tertiary, and Kecent deposits, but also, as I have shown, in
* Silliman^s Journal [2] , xxix. , p. 284 ; xxxii. , p. 286. Geology of
Canada, p. 577.
THE PRESERVATION OP EOZOON.
119
Lower Silurian strata."''" This hydrous silicate of protoxide of
iron and potash, which sometimes includes a considerable
])roportion of alumina in its composition, has been observed
by Ehrenberg, Mantell, and Bailey, associated with organic
forms in a manner which seems identical with that in which
pyroxene, serpentine, and loganite occur with the Eozoon in
the Laurentian limestones. According to the first of these
observers, the grains of green-sand, or glauconite, from the
Tertiary limestone of Alabama, are casts of the interior of
Polythalamia, the glauconite having filled them by * a species
of natural injection, which is often so perfect that not only the
large and coarse cells, but also the very finest canals of the
cell-walls and all their connecting tubes, are thus petrified and
separately exhibited.' Bailey confirmed these observations,
and extended them. He found in various Cretaceous and
Tertiary limestones of the United States, casts in glauconite,
not only of Foraminlfera, but of spines of EcMmis, and of the
cavities of corals. Besides, there were numerous red, green,
and white casts of minute anastomosing tubuli, which, accord-
ing to Bailey, resemble the casts of the boles made by bur-
rowing sponges (Cliona) and worms. These forms are seen
after the dissolving of the carbonate of lime by a dilute acid.
He found, moreover, similar casts of Foramhiifera, of minute
mollusks, and of branching tubuli, in mud obtained from
soundings in the Gulf Stream, and concluded that the deposi-
tion of glauconite is still going on in the depths of the sea,t
Pourtales has followed up these investigations on the recent
formation of glauconite in the Gulf Stream waters. He has
observed its deposition also in the cavities of Millepores, and
in the canals in the shells of Balanus. According to him, the
glauconite grains formed in Foraminifera lose after a time
their calcareous envelopes, and finally become ' conglomerated
into small black pebbles,' sections of which still show under a
microscope the characteristic spiral arrangement of the cells.J
* Sillimayi's Journal [2] , xxxiii., p. 277. Geology of Canada,
p. 487.
t SilUman^s Journal [2] , xxii., p. 280.
X Report of United States Coast-Survey , 1858, p. 243.
120
TnE DAWN OP LIFE.
" It appears probable from these observations that glanconitn
is formed by chemical reactions in the ooze at the bottom of
t]ie sea, where dissolved silica comes in contact with iron
oxide rendered so^ ' '" by organic matter; the resulting
silicate deposits it^ m the cavities of shells and other
vacant spaces. A process analagous to this in its results, has
filled the chambers and canals of the Laurcntian Foramhiifera
with other silicates; from the comparative rarity of mechani-
cal impurities in these silicates, however, it would appear that
they were deposited in clear water. Alumina and oxide of
iron enter into the composition of loganite as well as of glau-
conite ; but in the other replacing minerals, pyroxene and
serpentine, we have only silicates of lime and magnesia, which
were probably formed by the direct action of alkaline silicates,
either dissolved in surface-waters, or in those of submarine
springs, upon the cr reous and magnesian salts of the sea-
water."
[As stated in the te^c, the canals of Eozoon arc sometimes
filled with dolomite, or in part with serpentine and in part
with dolomite.]
(B.) Silurian Limestones holding Fossils infiltrate© with
Hydrous Silicate.
Since my attention has been directed to this subject, many
illustrations have come under my notice of Silurian limestones
in which the pores of fossils are infiltrated with hydrous
silicates akin to glauconite and serpentine. A limestone of
this kind, collected by Mr. Kobb, at Pole Hill, in New Bruns vvick,
afibrded not only beautiful specimens of portions of Crinoids
preserved in this way, but a sufficient quantity of the material
was collected for an exact analysis, a note on which was pub-
lished in the Proceedings of the Eoyal Irish Academy, 1871.
The limestone of Pole Hill is composed almost wholly of
organic fragments, cemented by crystalline carbonate of lime,
and traversed by slender veins of the same mineral. Among
the fragments may be recognised under the microscope por-
tions of Trilobites, and of brachiopod and gasteropod shells,
and numerous joints and plates of Crinoids. The latter are
THE PRESERVATION OP EOZOON.
121
remarkable for the manner in which their reticulated structure,
wliich is similar to that of modern Crinoids, has been injected
with a silicious substance, which is seen distinctly in slices,
and still more ])lainly in decalcified specimens. This fillings is
precisely similar in appearance to the serpentine filling the
canals of Eozoon, the only apparent difiorcnco being in the
forms of the cells and tubes of the Crinoids, as compared with
those of the Laurentian fossil ; the same silicious snbstanco
also occupies the cavities of some of the small shells, and
occurs in mere amorphous pieces, apparently filling interstices*
From its mode of occurrence, I have not the slightest doubt
that it occupied the cavities of the crinoidal fragments while
still recent, and before they had been cemented together by
the calcareous paste. This silicious filling is therefore similar
on the one hand to that eirected by the ancient serpentine of
the Laurentian, and on the other to that which results from the
depositions of modern glauconitt. The analysis of Dr. Hunt,
which I give below, fully confirms these analogies.
I may add that I have examined nnder the microscope por-
tions of the substance prepared by Dr. Hunt for analysis, and
find it to retain its form, showing that it is the actual filling
of the cavities. I have also examined the small amount of
insoluble silica remaining after his treatment with acid and
alkaline solvents, and find it to consist of angular and rounded
grains of quartzose sand.
The following are Dr. Hunt's notes : —
"The fossiliferous limestone from Pole Hill, New Brunswick,
probably of Upper Silurian age, is light gray and coarsely
granular. When treated with dilute hydrochloric acid, it
leaves a residue of 59 per cent., and the solution gives 1'8 per
cent, of alumina and oxide of iron, and magnesia equal to 1'35
of carbonate — the remainder being carbonate of lime. The
insoluble matter separated by dilute acid, after washing by
decantation from a small amount of fine flocculent matter,
consists, apart from an admixture of quartz grains, entirely of
casts and moulded forms of a peculiar silicate, which Dr.
Dawson has observed in decalcified specimens filling the pores
of crinoidal stems ; and which when separated by an acid;,
iMiJ
1 I
".iiMlili
122
THE DAWN OF LIFE,
resembles closely under the microscope tlie corralloidal forms
o£ arragonite known as flos fcrri, the surfaces being somewhat
rugose and glistening with crystalline faces. This silicate is
sub-translucent, and of a pale green colour, but immediately
becomes of a light reddish brown when heated to redness in
the air, and gives off water when heated in a tube, without
however, changing its form. It is partially decomposed by
strong hydrochloric acid, yielding a considerable amount of
protosalt of iron. Strong hot sulphuric acid readily and com-
pletely decomposes it, showing it to be a silicate of alumina
and ferrous oxide, with some magnesia and alkalies, but with
no trace of lime. The separated silica, which remains after the
action of the acid, is readily dissolved by a dilute solution of
soda, leaving behind nothing but angular and partially rounded
grains of sand, chiefly of colourless vitreous quartz. An
analysis effected in the way just described on 1'187 grammes
gave the following results, which give, by calculation, the cen-
tesimal composition of the mineral : —
i i: iii
nil
i!
Silica ....
•3290 . . .
Alumina . . .
•2440 . . .
Protoxyd of iron.
•1593 . . .
Magnesia . . .
•0360 . . .
Potash ....
•0140 . . .
Soda ....
•0042 . . .
"Water ....
•0584 . . .
Insoluble, quartz
•3420
38-93
=
20-77 oxygen
28-88
=
13-46
18-86 ^
4-25
1^69
" =
6-29 „
•48
6^91
^
6-14 „
1-1869
100-00
" A previous analysis of a portion of the mixture by fusion
with carbonate of soda gave, by calculation, 18"80 p. c. of pro-
toxide of iron, and amounts of alumina and combined silica
closely agreeing with those just given.
" The oxygen ratios, as above calculated, are nearly as 3 : 2 :
1 : 1. This mineral approaches in composition to the jollyte of
Yon Kobell, from which it differs in containing a portiou of
alkalies, and only one half as much water. In these respects
it agrees nearly with the silicate found by Eobert Hoffman, at
Kaspenau, in Bohemia, where it occurs in thin layers alterua-
THE PRESERVATION OF EOZOON.
123
ting with picrosmine, and surrounding masses of Eozoon in
the Laurentian limestones of that region ;* the Eozoon itself
being there injected "with a hydrous silicate which may be
described as intermediate between glauconitc and chlorite in
composition. The mineral first mentioned is compared by
Hoffman to fiihlunite, to which jollyte is also related in physical
characters as well as in composition. Under the names of
fahlunite, gigantolite, pinite, etc., are included a great class of
hydrous silicates, which from their imperfectly crysttilline
condition, have generally been regarded, like serpentine, as
results of the alteration of other silicates. It is, however,
difficult to admit that the silicate found in the condition
described by Hoffman, and still more the present mineral,
which injects the pores of pala30zoic Crinoids, can be any other
than an criginal deposition, allied in the mode of its formation,
to the serpentine, pyroxene, and other minerals which have
injected the Laurentian Eozoon, and the serpentine and
glauconite, which in a similar manner fill Tertiary and recent
shells."
(C.) Various Minerals filling Cavities of Fossils in the
Laurentian.
The following on this subject is from a memoir by Dr. Hunt
in the Twenty-first Report of the Regents of the University of
New York, 1874 :—
"Kecent investigations have shown that in some casos the
dissemination of certain of these minerals through the crys-
talline limestones is connected with organic forms. The ob-
servations of Dr. Dawson and myself on the Eozoon Canatlense
showed that certain silicates, namely serpentine, pyroxene, and
loganite, had been deposited in the cells and chambers left
vacant by the disappearance of the animal matter from the
calcareous skeleton of the foraminiferous organism ; so nhat
when this calcareous portion is removed by an acid tliere
remains a coherent mass, which is a cast of the soft part.s of
* Joum. fiir Prakt. Chemie, BJ. 106 (Erster Jahrgaug, 1809) , p.
35G.
fjt i ?'
♦ i
.■.;^
\m
I iii
124
THE DAWN OP LIFE.
the animal, in which, not only the chambers and connecting
canals, but the minute tubuli and pores are represented by-
solid mineral silicates. It was shown that this process must
have taken place immediately after the death of the animal,
and must have depended on the deposition of these silicates
from the waters of the ocean.
" The train of investigation thus opened up, has been pursued
by Dr. Giimbel, Director of the Geological Survey of Ba-
varia, who, in a recent remarkable memoir presented to the
Royal Society of that country, has detailed his results.
" Having first detected a fossil identical with the Canadian
Eozoon (together with several other curious microscopic
organic forma not yet observed in Canada), replaced by ser-
pentine in a crystalline limestone from the primitive group of
Bavaria, which he identified with the Laurentian system of
this country, he next discovered a related organism, to which
he has given the name of Eozoon Bavaricum. This occurs in a
crystalline limestone belonging to a series of rocks more
recent than the Laurentian, but older than the Primordial
zone of the Lower Silurian, and designated by him the
Hercynian clay slate series, which he conceives may repre-
sent the Cambrian system of Great Britain, and perhaps cor-
respond to the Huronian series of Canada and the United
States. The cast of the soft parts of this new fossil is, accord-
ing to Giimbel, in part of serpentine, and in part of horn-
blende.
" His attention was next directed to the green hornblende
(pargasite) which occurs in the crystalline limestone of Pargas
in Finland, and remains when the carbonate of lime is dissolved
as a coherent mass closely resembling that left by the irregu-
lar and acervuline forms of Eozoon. The calcite walls also
sometimes show casts of tubuli. ... A white mineral,
probably scapolite was found to constitute some tubercles
associated with the pargasite, and the two mineral species
were in some cases united in the same rounded grain.
•' Similar observations were made by him upon specimens of
ooccolite or green pyroxene, occurring in rounded and wrinkled
grains in a Laurentian limestone from New York. These,
THE PRESERVATION OP EOZOON.
125
according to Giirabel, present the same connecting cylinders
and branching stems as the pargasite, and are by him supposed
to have been moulded in the same manner. . . . Yery
beautiful evidences of the same organic structure consisting
of the casts of tubuli and their ramifications, were also ob-
served by Giimbel in a purely crystalline limestone, enclosing
granules of chondrodite, hornblende, and garnet, from Boden
in Saxony. Other specimens of limestone, both with and
without serpentine and chondrodite, were examined with-
out exhibiting any traces of these peculiar forms ; and these
negative results are justly deemed by Giimbel as going to
prove thab the structure of the others is really, like that of
Eozoon, the result o£ the intervention of organic forms.
Besides the minerals observed in the replacing substance of
Eozoon in Canada, viz., serpentine, pyroxene, and loganite,
Giimbel adds chondrodite, hornblende, scapolite, and probably
also pyrallolite, quartz, iolite, and dichroite,"
(D.) Glauconites.
The following is from a paper by Dr. Hunt in the Report of
the Survey of Canada for 1866 : —
" In connection with the Eozoon it is interesting to examine
more carefully into the nature of the matters which have been
called glauconite or green-sand. These names have been
given to substances of unlike composition, which, however,
occur under similar conditions, and appear to be chemical
deposits from water, filling cavities in minute fossils, or
forming grains in sedimentary rocks of various ages. Al-
though greenish in colour, and soft and earthy in texture, it
will be seen that the various glauconites diflTer widely in
composition. The variety best known, and commonly regarded
as the type of the glauconites, is that found in the green-sand of
Cretaceous age in New Jersey, and in theTertiary of Alabama;
the glauconite from the Lower Silurian rocks of the Upper
Mississippi is identical with it in composition. Analysis
shows these glauconites to bo essentially hydrous silicates of
protoxyd of iron, with more or less alumina, and small but
TPT
126
THE DAWN OP LIFE.
Ill iM'i'
I iiii'i
variable quantities of magnesia, besides a notable amount of
potash. This alkali is, however, sometimes wanting, as ap-
pears from the analysis of a green- sand from Kent in England,
by that careful chemist, the late Dr. Edward Turner, and in
another examined by Berthier, from the calcaire grassier, near
Paris, which is essentially a serpentine in composition, being
a hydrous silicate of magnesia and protoxyd of iron. A com-
parison of these last two will show that the loganite, which
tills the ancient Foraminifer of Burgess, is a silicate nearly
related in composition.
I. Green-sand from the calcaire grassier, near Paris.
Berthier (cited by Beudant, Mineralagie, ii., 178).
II. Green-sand from Kent, England. Dr. Edward Turner
(cited by Eogers, Final Eeport, Geol. N. Jersey, page 206).
III. Loganite from the Eozoon of Burgess.
IV. Green-sand, Lower Silurian ; Red Bird, Minnesota.
y. Green- sand, Cretaceous, New Jersey.
VI. Green-sand, Lower Silurian, Orleans island.
The last four analyses are by myself.
I.
Silica 40-0
Protoxyd of iron 24*7
Magnesia IG'6
Lime 3-3
Alumina 1*7
Potash
Soda
II.
48-5
22-0
3-8
170
traces.
Water
III.
IV.
V.
VI.
35-14
46-58
50-70
50-7
8-60
20-61
22-50
8-6
31-47
1-27
2-16
3-7
2-49
1-11
10-15
11-45
8-03
19-8
6-96
6-80
8-2
•98
•75
•5
14-64
9-66
8-95
8-5
12-6 7-0
98-9 98^3 100-00 100-00 100-00 100-0
VI.
50-7
8-6
3-7
•5
8-5
m '-'1
Plate YI.
Imii a Plxotc 'bvVi^iircii
Ihma-i&xiisDagfi^IjUj
CANAL SYSTEM CF EOZCON.
SLICES or THE FOSSIL (MAGNITTED.)
To£dCC QlMf 6.
CHAPTER VI.
CONTEMPORARIES AND SUCCESSORS OF EOZOON.
The name Eozoon, or Dawn- animal, raises the
question whether we shall ever know any earlier repre-
sentative of animal life. Here I think it necessary to
explain that in suggesting the name Eozoon for the
earliest fossil, and Eozoic for the formation in which it
is contained, I had no intention to affirm that there
may not have been precursors of the Dawn -animal.
By the similar term. Eocene, Lyell did not mean to
affirm that there may not have been modern types in
the preceding geological periods : and so the dawn
of animal life may have had its gray or rosy breaking
at a time long anterior to that in which Eozoon built its
marble reefs. When the fossils of this earlv auroral
time shall be found, it will not be hard to invent ap-
propriate names for them. There are, however, two
reasons that give propriety to the name in the present
state of our knowledge. One is, that the Lower Lau-
rentian rocks are absolutely the oldest that have yet
come under the notice of geologists, and at the present
moment it seems extremely improbable that any older
sediments exist, at least in a condition to be recognised
* as such. The other is that Eozoon, as a member of
;l¥'
!!! !!'!!!!!
Mill
i !
I !-!
J28
THE DAWN OP LIFE.
the group Protozoa, of gigantic size and comprelien-
sive type, and oceanic in its habitat^ is as likely as
any other creature that can be imagined to have been
the first representative of animal life on our planet.
Vegetable life may have preceded it, nay probably did
so by at least one great creative a3on, and may have
accumulated previous stores of organic matter ; but if
any older forms of animal life existed, it is certain at
least that they cannot have belonged to much simpler
or more comprehensive types. It is also to be ob-
served that such forms of life, if they did exist, may
have been naked protozoa, which may have left no
sign of their existence except a minute trace of car-
bonaceous matter, and perhaps not even this.
But if we do not know, and perhaps we are not
likely to know, any animals older than Eozoon, may
we not find traces of some of its contemporaries,
either in the Eozoon limestones themselves, or other
rocks associated with them ? Here we must admit
that a deep sea Foraminiferal limestone may give a
very imperfect indication of the fauna of its time. A
dredger who should have no other information as to
the existing population of the world, except what he
could gather from the deposits formed under several
hundred fathoms of water, would necessarily have very
inadequate conceptions of the matter. In like manner
a geologist who should have no other information as
to the animal life of the Mesozoic ages than that fur-
nished by some of the thick beds of white chalk
might imagine that he had reached a period when the
car-
CONTEMPORARIES AND SUCCESSORS OF EOZOON. 129
simplest kinds of protozoa predominated over all other
forms of life; but this impression would at once be
corrected by the examination of other deposits of the
same age : so our inferences as to the life of the Lau-
rentian from the contents of its oceanic limestones
may be very imperfect, and it may yet yield other and
various fossils. Its possibilities are, however, limited
by the fact that before we reach this great ^depth in
the earth^s crust, we have already left behind in much
newer formations all traces of animal life except a few
of the lower forms of aquatic invertebrates ; so that we
are not surprised to find only a limited number of
living things, and those of very low type. Do we
then know in the Laurentian even a few distinct
species, or is our view limited altogether to Eozoon
Canadense ? In answering thi? question we must bear
in mind that the Laurentian itself was of vast dura-
tion, and that important changes of life may have
taken place even between the ^deposition of the Eozoon
limestones and that of those rocks in which we find
the comparatively rich fauna of the Primordial age.
'^^Chis subject was discussed by the writer as early as
1865, and I may repeat here what could be said in
relation to it at that time : —
^*'In connection with these remarkable remains, it
appeared desirable to ascertain, if possible, what share
these or other organic structures may have had in the
accumulation of the limestones of the Laurentian
series. Specimens were therefore selected by Sir W.
E. Logan, and slices were prepared under his direc-
'■m
! I>
!
130
THE DAWN OP LIFE.
tion. On microscopic examination, a number of these
were found to exhibit merely a granular aggregation
of crystals, occasionally with particles of graphite and
other foreign minerals, or a laminated mixture of
calcareous and other matters, in the manner of some
more modern sedimentary limestones. Others, how-
ever, were evidently made up almost entirely of frag-
ments of Eozoon, or of mixtures of these with other
calcareous and carbonaceous fragments which afford
more or less evidence of organic origin. The contents
of these organic limestones may be considered under
the following heads : —
1 . Eemains of Eozoon.
2. Other calcareous bodies, probably organic.
3. Objects imbedded in the serpentine.
4. Carbonaceous matters.
5. Perforations, or worm-burrows.
" 1. The more perfect specimens of Eozoon do not
constitute the mass of any of the larger specimens in
the collection of the Survey ; but considerable portions
of some of them are made up of material of similar
minute structure, destitute of lamination, and irregu-
larly arranged. Some of this material gives the im-
pression that there may have been organisms similar
to Eozoon, but growing in an irregular or acervuline
manner without lamination. Of this, however, I
cannot be certain; and on the other hand there is
distinct evidence of the aggregation of fragments of
Eozoon in some of these specimens. In some they
CONTEMPORARIES AND SUCCESSORS OF EOZOON. 181
constitute the greater part of tlie mass. In others
they are embedded in calcareous matter of a different
character, or in serpentine or granular pyroxene. In
most of the specimens the cells of the fossils are more
or less filled with these minerals; and in some in-
stances it would appear that the calcareous matter of
fragments of Eozoon has been in part replaced by ser-
pentine."
" 2. Intermixed with the fragments of Eozoon above
referred to, are other calcareous matters apparently
fragmentary. They are of various angular and
rounded forms, and present several kinds of structure.
The most frequent of these is a strong lamination
varying in direction according to the positron of the
fragments, but corresponding, as far as can be ascer-
tained, with the diagonal of the rhombohedral cleavage.
This structure, though crystalline, is highly character-
istic of crinoidal remains when preserved in altered
limestones. The more dense parts of Eozoon, destitute
of tubuli, also sometimes show this structure, though
less distinctly. Other fragments are compact and
structureless, or show only a fine granular appearance;
and these sometimes include grains, patches, or fibres
of graphite. In Silurian limestones, fragments of
corals and shells which have been partially infiltrated
with bituminous matter, show a structure like this.
On comparison with altered organic limestones of the
Silurian system, these appearances would indicate that
in addition to the debris of Eozoon, other calcareous
structures, more like those of criuoids, corals, and
Uh Jf
mf
132
THE DAWN OP LIFE.
■i!!i|i
MiiiHI
iijiM;
shoUs, liavo contributed to tlio formation of the Lan-
rentian limestones.
"3. In the serpentine* filHng the chambers of a
large specimen of Eozoon from Burgess, there are
numerous small pieces of foreign matter; and the
silicate itself is laminated, indicating its sedimentary
nature. Some of the included fragments appear to be
carbonaceous, others calcareous; but no distinct or-
ganic structure can be detected in them. There are,
however, in the serpentine, many minute silicious
grams of a bright green colour, resembling green-
sand concretions ; and the manner in which these are
occasionally arranged in lines and groups, suggests the
supposition that they may possibly be casts of the
interior of minute Foraminiferal shells. They may,
however, be concretionary in their origin.
" 4. In some of the Laurentian limestones submitted
to me by Sir V/. E. Logan, and in others which I col-
lected some years ago at Madoc, Canada West, there
are fibres and granules of carbonaceous matter, which
do not conform to the crystalline structure, and present
forms quite similar to those which in more modern
limestones result from the decomposition of algae.
Though r .taining mere traces of organic structure, no
doubt would be entertained as to their vegetable origin
if they were found in fossiliferous limestones.
" 5. A specimen of impure limestone from Madoc,
in the collection of the Canadian Geological Survey,
which seems from its structure to have been a finely
* This is the dark green mineral named loganite by Dr. Hunt .
CONTEMPORARIES AND SUCCESSORS OP EOZOON. 133
laminated sediment, shows perforations of various
sizes, somewhat scalloped at the sides, and filled with
grains of rounded silicious sand. In my own collec-
tion there aro specimens of micaceous slate from the
same region, with indications on their weathered sur-
faces of similar rounded perforations, having the
aspect of Scolithus, or of worm-burrows.
" Though the abundance and wide distribution of
Eozoon, and the important part it seems to have acted
in the accumulation of limestone, indicate that it was
one of the most prevalent forms of animal existence in
the seas of the Laurentian period, the non-existence of
other organic beings is not implied. On the contrary,
independently of the indications afforded by the lime-
stones themselves, it is evident that in order to the
existence and growth of these large Ehizopods, the
waters must have swarmed with more minute animal
or vegetable organisms on which they could subsist.
On the other hand, though this is a less certain infer-
ence, the dense calcareous skeleton of Eozoon may
indicate that it also was liable to the attacks of animal
enemies. It is also possible that the growth of
Eozoon, or the deposition of the serpentine and pyrox-
ene in which its remains have been preserved, or both,
may have been connected with certain oceanic depths
and conditions, and that we have as yet revealed to us
the life of only certain stations in the Laurentian seas.
Whatever conjectures we may form on these more
problematic points, the observations above detailed
appear to establish the following conclusions : —
'^jT'^jr-t'^'
lllil!
iil!
134
THE DAWN OF LIFE.
'' First, that in tlie Laurentian period, as in subse-
quent geological epochs, the Khizopods were important
agents in the accumulation of beds of limestone ; and
secondly, that in this early period these low forms of
animal life attained to a development, in point of mag-
nitude and complexity, unexampled, in so far as yet
known, in the succeeding ages of the earth's history.
This early culmination of the Rhizopods is in accord-
ance with one of the great laws of the succession of
living beings, ascertained from the study of the intro-
duction and progress of other groups ; and, should it
prove that these great Protozoans were really the
dominant type of animals in the Laurentian period,
this fact might be regarded as an indication that in
these ancient rocks we may actually have the records
of the first appearance of animal life on our planet. ''
With reference to the first of the above heads, I
have now to state that it seems quite certain that the
upper and younger portions of the masses of Eozoon
often passed into the acervuline form, and the period
in which this change took place seems to have de-
pended on circumstances. In some specimens there
are only a few regular layers, and then a heap of ir-
regular cells. In other cases a hundred or more
regular layers were formed ; but even in this case
little groups of irregular cells occurred at certain
points near the surface. This may bo seen in plate
III. I have also found some masses clearly not frag-
mental which consist altogether of acervuline cells. A
specimen of this kind is represented in fig. 31. It is
CONTEMPORARIES AND SUCCESSORS OF EOZOON. 135
oval in outline, about three inches in length, wholly
made up of rounded or cylindrical cells, the walls of
which have a beautiful tubular structure, but there is
little or no supplemental skeleton. Whether this is
a portion accidentally broken off from the top of a
mass of Eozoon, or a peculiar varietal form, or a dis-
1
Fig. 31. Acerviiline Variety of Eozoon, St. Pierre.
('».) General form, half natural size, (h.) Portion of cellular interior, magnifled,
showing the course of the tubuli.
tinct species, it would be difficult to determine. In the
meantime I have described it as a variety, " acervu-
lina/' of the species Eozoon Canadense.* Another
variety also, from Petite Nation, shows extremely thin
laminae, closely placed together and very massive, and
with little supplemental skeleton. This may be allied
to the last, and may be named variety " minor.'*
All this, however, has nothing to do with the layers
* Proceedings of Geolojical Society, 1875.
136
THE DAWN OF LIFE.
w
■M:J»^f
of fragments of Eozoon wliicli are scattered through
the Laurentian limestones. In these the fossil is
sometimes preserved in the ordinary manner, with its
cavities filled with serpentine, and the thicker parts of
the skeleton having their canals filled with this sub-
stance. In this case the chambers may have been
occupied with serpentine before it was broken up. At
St. Pierre there are distinct layers of this kind, from
half an inch to several inches in thickness, regularly
interstratified with the ordinary limestone. In other
layers no serpentine occurs, but the interstices of the
fragments are filled with crystalline dolomite or mag-
nesian limestone, which has also penetrated the canals;
and there are indications, though less manifest, that
some at least of the layers of pure limestone are com-
posed of fragmental Eozoon. In the Laurentian lime-
stone of Wentworth, belonging apparently to the same
band with that of St. Pierre, there are many small
rounded pieces of limestone, evidently the debris of
some older rock, broken up and rounded by attrition.
In some of these fragments the structure of Eozoon
may be plainly perceived. This shows that still older
limestones composed of Eozoon were at that time un-
dergoing waste, and carries our view of the existence
of this fossil back to the very beginning of the Lau-
rentian.
With respect to organic fragments not showing the
structure of Eozoon, I have not as yet been able to
refer these to any definite origin. Some of them may
be simply thick portions of the shell of Eozoon with
I! I 111! II!
l,llll.L. '
CONTEMrORAEIES- AND SUCCESSORS OF EOZOON. 137
their pores filled with calcite, so as to present a homo-
geneous appearance. Others have much the appear-
ance of fragments of such Primordial forms as Archceo-
cyatlms, to be described in the sequel ; but after much
careful search, I have thus far been unable to say more
than I could say in 1865.
+ 60
Fig. 32. Archaospherince from St. Fierre.
('X.) Siiecimcns dissolved out by acid. The lower one showing interior soptn.
(h.) Specimens seen in section.
Fio. 33. Archaospherina; from Burgess Eozoon.
Magnified.
It is different, however, with the round cells infil-
trated with serpentine and with the silicious grains
included in the loganite. I have already referred to
138
THE DAWN OF LIFE.
%<4
1
i'r
1
1,
IBS i
_i_Lii
t
#
lii'illil 111
^IPfT
i
and figured (fig. 18) the remarkable rounded bodies
occurring at Long Lake. I now figure similar bodies
found mixed with fragmental Eozoon and in separate
thin layers at St. Pierre (fig. 32), also some of the
singular grains found in the loganite occuping the
chambers of Eozoon from Burgess (fig. 33), and ;i
Fig. 34. Archaospherina; from Wenticorth Limestone.
Magnified.
beaded body set free by acid, with others of irregu-
lar forms, from the limestone of Wentworth (fig.
34). All these I think are essentially of the same
nature, namely, chambers originally invested with a
tubulated wall like Eozoon, and aggregated in groups,
CONTEMPORARIES AND SUCCESSORS OF EOZOON. 139
sometimes in a liuear manner, sometimes spirally, like
those Globigerinae which constitute the mass of modern
deep-sea dredgings and also of the chalk. These
bodies occur dispersed in the limestone, arranged in
thin layers parallel to the bedding or sometimes in the
large chamber-cavities of Eozoon. They are so varia-
ble in size and form that it is not unlikely they may
be of difierent origins. The most probable of these
may be thus stated. First, they may in some cases
be the looser superficial parts of the surface of Eozoon
broken up into little groups of cells. Secondly, they
may be few-celled germs or buds given ofiP from
Eozoon. Thirdly, they may be smaller Foraminifera,
structurally allied to Eozoon, but in habit of growth
resembling those little globe-shaped forms which, as
already stated, abound in chalk and in the modern
ocean. The latter view I should regard as highly
probable in the case of many of them ; and I have
proposed for them, in consequence, and as a convenient
name, Archceospherince, or ancient spherical animals.
Carbonaceous matter is rare in the true Eozoon
limestones, and, as already stated, I would refer the
Laurentian graphite or plumbago mainly to plants.
With regard to the worm-burrows referred to in 1865,
there can be no doubt of their nature, but there is
some doubt as to whether the beds that contain them
are really Lower Laurentian. They may be Upper
Laurentian or Huronian. I give here figures of these
burrows as published in 1866* (fig. 35). The rocks
* Journal of Geological Society.
MO
THE DAWN OP LIFE.
4 IS
S 111 I
which contain them hold also fragments of Eozoon,
and are not known to contain other fossils.
d V c d
Fig. 35. Annelid Burrows, Laurcntian or Iluronian.
Fig 1. Transverse section of Worm-hurrow—mtigniRcA, as a transparent object.
((7.) Calcareo-silicious rock. (&.) Space filled with calcareous spar, (r.)
Sand agglutinated and stained black, (d.) Sand less agglutinated and un-
coloured. Fig. 2. Transverse section of Worm-burrow on weathered surface,
natural size. Fig. 3. The same, magnified.
'
1 iilll
1 llili
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i
If we now turn to other countries in search of con-
temporaries of Eozoon, I may refer first to some speci-
mens found by my friend Dr. Honeyman at Arisaig, in
Nova Scotia, in beds underlying the Silurian rocks
of that locality, but otherwise of uncertain age. I do
not vouch for them as Laurentian, and if of that age
they seem to indicate a species distinct from that of
Canada proper. They differ in coarser tubulation,
and in their canals being large and beaded, and less
divergent. I proposed for these specimens, in some
notes contributed to the survey of Canada, the name
Eozoon Acadianum.
Dr. Gumbel, the Director of tbe Geological Sr.rvey
CONTEMPORARIES AND StJCCESSOES OF EOZOON. 141
.I'vey
of Bavaria, is one of the most active and widely in-
formed of European geologists, combining European
knowledge with an extensive acquaintance with the
larger and in some respects more typical areas of the
older rocks in America, and stratigraphical geology
with enthusiastic interest in the microscopic structures
of fossils. He at once and in a most able manner took
up the question of the application of the discoveries
in Canada to the rocks of Bavaria. The spirit in
which he did so may be inferred from the following
extract : —
" The discovery of organic remains in the crystalline
limestones of the ancient gneiss of Canada, for which
we are indebted to the researches of Sir William
Logan and his colleagues, and to the careful micro-
scopic investigations of Drs. Dawson and Carpenter,
must be regarded as opening a new era in geological
science.
''This discovery overturns at once the notions
hitherto commonly entertained with regard to the
origin of the stratified primary limestones, and their
accompanying gneissic and quartzose strata, included
under the general name of primitive crystalline schists.
It shows us that these crystalline stratified rocks, of
the so-called primary system, are only a backward
prolongation of the chain of fossiliferous strata ; the
elements of which were deposited as oceanic sediment,
like the clay -slates, limestones, and sandstones of the
paleozoic formations, and under similar conditions,
though at a time far more remote, and more favour-
142
THE DAWN OF LIFE.
I iiil liir;.:
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•
able to tlie generation of crystalline mineral com-
pounds.
" In this discovery of organic remains in the primary
rocks, we hail with joy the dawn of a new epoch in
the critical history of these earlier formations. Al-
ready in its light, the primeval geological time is
seen to be everywhere animated, and peopled with
new animal forms of whose very existence we had
previously no suspicion. Life, which had hitherto
been supposed to have first appeared in the Primordial
division of the Silurian period, is now seen to be
immeasurably lengthened beyond its former limit, and
to embrace in its domain the most ancient known
portions of the earth's crust. It would almost seem
as if organic life had been awakened simultaneously
with the solidification of the earth's crust.
" The great importance of this discovery cannot be
clearly understood, unless we first consider the various
and conflicting opinions and theories which had
hitherto been maintained concerning the origin of
these primary rocks. Thus some, who consider them
as the first-formed crust of a previously molten globe,
regard their apparent stratification as a kind of con-
centric parallel structure, developed in the progressive
cooling of the mass from without. Others, while ad-
mitting a similar origin of these rocks, suppose their
division into parallel layers to be due, like the lamina-
tion of clay-slates, to lateral pressure. If we admit
such views, the igneous origin of schistose rocks be-
comes conceivable, and is in fact maintained by many.
CONTEMPORARIES AND SUCCESSORS OF EOZOON. 1 J-3
'^ On the otlier hand, we have the school which, while
recognising the sedimentary origin of these crystalline
schists, supposes them to have been metamorphosed at
a later period ; either by the internal heat, acting in the
deeply buried strata; by the proximity of eruptive
rocks ; or finally, through the agency of permeating
waters charged with certain mineral salts.
"A. few geologists only have hitherto inclined to the
opinion that these crystalline schists, while possessing
real stratification, and sedimentary in their origin,
were formed at a period when the conditions were
more favourable to the production of crystalHne ma-
terials than at present. According to this view, the
crystalline structure of these rocks is an original con-
dition, and not one superinduced at a later period by
metamorphosis. In order, however^ to arrange and
classify these ancient crystalline rocks, it becomes
necessary to establish by superposition, or by other
evidence, differences in age, such as are recognised in
the more recent stratified deposits. The discovery of
similar organic remains, occupying a determinate po-
sition in the stratification, in different and remote
portions of these primitive rocks, furnishes a powerful
argument in favour of the latter view, as opposed to
the notion which maintains the metamorphic origin of
the various minerals and recks of these ancient forma-
tions j so that we may regard the direct formation of
these mineral elements, at least so far as these fossili-
ferous primary limestones are concerned, as an es-
tablished fact."
Wi'
■nt
144
THE DAWN OP LIFE.
iiiiili
ill I I
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if:
^-"mmi
His first discovery is thus recorded, in terms which
show the very close resemblance of the Bavarian and
Canadian Eozoic.
*'My discovery of similar organic remains in the
serpentine-limestone from near Passau was made in
1865, when I had returned from my geological labours
of the summer, and received the recently published
descriptions of Messrs. Logan, Dawson, etc. Small
portions of this rock, gathered in the progress of
the Geological Survey in 1854, and ever since pre-
served in my collection, having been submitted to
microscopic examination, confirmed in the most bril-
liant manner the acute judgment of the Canadian geo-
logists, and furnished palasontological evidence that,
notwithstanding the great distance which separates
Canada from Bavaria, the equivalent primitive rocks
of the two regions are characterized by similar or-
ganic remains; showing at the same time that the
law governing the definite succession of organic life
on the earth is maintained even in these most ancient
formations. The fragments of serpentine-limestone,
or ophicalcite, in which I first detected the existence
of Eozoon, were like those described in Canada, in
which the lamellar structure is wanting, and off'er only
what Dr. Carpenter has called an acervuline structure.
For further confirmation of my observations, I deemed
it advisable, through the kindness of Sir Charles Lyell,
to submit specimens of the Bavarian rock to the exami-
nation of that eminent authorityj Dr. Carpenter, who,
without any hesitation, declared them to contain Eozoon.
CONTEMPORARIES AND SUCCESSORS OF EOZOON. 145
" This fact being established, I procured from the
quarries near Passau as many specimens of the lime-
stone as the advanced season of the year would per-
mit ; and, aided by my diligent and skilful assistants,
Messrs. Reber and Schwager, examined them by the
methods indicated by Messrs. Dawson and Carpenter.
In this way I soon convinced myself of the general
similarity of our organic remains with those of Canada.
Our examinations were made on polished sections and
in portions etched with dilute nitric acid, or, better,
with warm acetic acid. The most beautiful results
were however obtained by etching moderately thin
sections, so that the specimens may be examined at
will either by reflected or transmitted light.
" The specimens in which I first detected Eozoon
came from a quarry at Steinhag, near Obernzell, on
the Danube, not far from Passau. The crystalline
limestone here forms a mass from fifty to seventy
feet thick, divided into several beds, included in the
gneiss, w^hose general strike in this region is N.W.,
with a dip of 40°-60° N.E. The limestone strata of
Steinhag have a dip of 45° N.E. The gneiss of this
vicinity is chiefly grey, and very silicious, containing
dichroite, and of the variety known as dichroite-
gneiss ; and I conceive it to belong, like the gneiss of
Bodenmais and Arber, to that younger division of the
primitive gneiss system which I have designated as
the Hercynian gneiss formation; which, both to the
north, between Tischenreuth and Mahring, and to the
south on the north-west of the mountains of Ossa,
L
146
THE DAWN OP LIFE.
w
is immediately overlaid by the mica-slate formation.
Lithologically, this newer division of tho gneiss is
characterized by the predominance of a grey variety,
rich in quartz, with black magnesian-mica and ortho-
clase, besides which a small quantity of oligoclase is
never wanting. A further characteristic of this Her-
cynian gneiss is the frequent intercalation of beds of
rocks rich in hornblende, silch as hornblende- schist,
amphibolite, diorite, syenite, and syenitic granite, and
also of serpentine and granulite. Beds of granular
limestone, or of calcareous schists are also never alto-
gether wanting ; while iron pyrites and graphite, in
lenticular masses, or in local beds conformable to the
great mass of the gneiss strata, are very generally
present.
" In the large quarry of Steinhag, from which I first
obtained the Eozoon, the enclosing rock is a grey
homblendio gneiss, which sometimes passes into a
hornblende-slate. The limestone is in many places
overlaid by a bed of hornblende-schist, sometimes five
feet in thickness, which separates it from the normal
gneiss. In many localities, a bed of serpentine, three
or four feet thick, is interposed between the limestone
and the hornblende- schist ; and in some cases a zone,
consisting chiefly of scapolite, crystalline and almost
compact, with an admixture however of hornblende and
chlorite. Below the serpentine band, the crystalline
limestone appears divided into distinct beds, and en-
closes various accidental minerals, among which are
reddish-white mica, chlorite, hornblende, tremolite.
CONTEMPORARIES AND SUCCESSORS OP EOZOON. 147
cliondrodite, rosellan, garnet, and scapolite, arranged
in bands. In several places the lime is mingled with
serpentine, grains or portions of which, often of the
size of peas, are scattered through the limestone with
apparent irregularity, giving rise to a beautiful variety
of ophicalcite or serpentine-marble. These portions,
which are enclosed in the limestone destitute of ser-
pentine, always present a rounded outline. In one
instance there appears, in a high naked wall of lime-
stone without serpentine, the outline of a mass of
ophicalcite, about sixteen feet long and twenty-five
feet high, which, rising from a broad base, ends in a
point, and is separated from the enclosing limestone
by an undulating but clearly defined margin, as al-
ready well described by Wineberger. This mass of
ophicalcite recalls vividly a reef-like structure. With-
in this and similar masses of ophicalcite in the crystal-
line limestone, there are, so far as my observations in
1854 extend, no continuous lines or concentric layers
of serpentine to be observed, this mineral being al-
ways distributed in small grains and patches. The
few apparently regular layers which may be observed
are soon interrupted, and the whole aggregation is
irregular.''
It will be observed that this acervuline Eozoon of
Steinhag appears to exist in large reefs, and that in
its want of lamination it differs from the Canadian
examples. In fossils of low organization, like Forami-
nifera, such differences are often accidental and com-
patible with specific unity, but yet there may be a
It \-
5;»
'ri.liRI'i i;i!!,::i;
148
THE DAWN OP LIFE.
difference specifically in the Bavarian Eozoon as com-
pared with the Canadian.
Giimbel also found in the Finnish and Bavarian
limestones knotted chambers^ like those of Wentworth
above mentioned (fig. 36), which he regards as be-
longing to some other organism than Eozoon ; and
flocculi having tubes, pores, and reticulations which
would seem to point to the presence of structures
akin to sponges or possibly remains of seaweeds.
These observations Giimbel has extended into other
localities in Bavaria and Bohemia, and also in Silesia
Fig, 36. Arclucospherince from Pargas in Finland. {Ajter Giimbel.)
Magnified.
and Sweden, establishing the existence of Eozoon
fossils in all the Laurentian limestones of the middle
and north of Europe.
Giimbel has further found in beds overlying the
older Eozoic series, and probably of the same age with
the Canadian Huroniau, a different species of Eozoon,
with smaller and more contracted chambers, and still
finer and more crowded canals. This, which is to be
regarded as a distinct species, or at least a well-marked
varietal form, he has named Eozoon Bacaricum (fig.
37). Thus this early introduction of life is not peculiar
to that old continent which we sometimes call the New
CONTEMPORARIES AND SUCCESSORS OF EOZOON. 149
World, but applies to Europe as well, and Europe has
famished a successor to Eozoon in the later Eozoic or
Huronian period. In rocks of this age in America,
after long search and much slicing of limestones, I
have hitherto failed to find any decided organic re-
mains other than the Tudor and Madoc specimens of
Eozoon. If these are really Huronian and nou Lau-
rentian, the Eozoon from this horizon does not sensibly
Uimbel.)
the
with
ozoon,
d still
to be
arked
(fig-
3culiar
3 New
Fia. 37. Section oj Eozoon Bavarlcum, with Serpentine, from the
Gnjstalline Limestone of the Ilercijnio primitive Clay-state Formation
at Hohenherg ; 25 diameters.
(«.) Sparry carbonate of lime. (&.) Cellular carbonate of lime, (c.) System of
tubiili. {(I.) Serpentine replacint? the coarser ordljiary variety. (i\) Serpen-
tine and hornblende replacing the finer variety, ir. the very mucli coutortod
portions.
differ from that of the Lower Laurentian. Tbo curious
limpet-like objects from Newfoundland, discovered by
Murray, and described by Billings,* under tho name
Aspldellaj are believed to be Huronian, but they have
no connection with Eozoon, and therefore need not
detain us here.
Leaving the Eozoic age, we find ourselves next in the
Primordial or Cambrian, and hero wo discover the sea
• Canadian Naturalist, 1871.
Ml
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150
THE DAWN OF LIFE.
already tenanted by many kinds of crustaceans and
shell-fishes, which have been collected and described
by palaeontologists in Bohemia, Scandinavia, Wales,
and North America ; * curiously enough, however, the
rocks of this age are not so rich in Foraminifera as
those of some succeeding periods. Had this primitive
type played out its part in the Eozoic and exhausted
its energies, and did it remain in abeyance in the
Primordial age to resume its activity in the succeeding
times ? It is not necessary to believe this. The
geologist is familiar with the fact, that in one forma-
tion he may have before him chiefly oceanic and deep-
sea deposits, and in another those of the shallower
waters, and that alternations of these may, in the same
age or immediately succeeding ages, present very dif-
ferent groups of fossils. Now the rocks and fossils of
the Laurentian seem to be oceanic in character, while
the Huronian and early Primordial rocks evidence
great disturbances, and much coarse and muddy sedi-
ment, such as that found in shallows or near the land.
They abound in coarse conglomerates, sandstones and
thick beds of slate or shale, but are not rich in limestones,
which do not in the parts of the world yet explored
regain their importance till the succeeding Siluro-
Cambrian age. No doubt there were, in the Primor-
dial, deep-sea areas swarming with. Foraminifera, the
successors of Eozoon; but these are as yet unknown
or little known, and our known Primordial fauna is
chiefly that of the shallows. Enlarged knowledge may
* BaiTande, Angelin, Hicks, Hall, BilHngs, etc.
CONTEMPORARIES AND SUCCESSORS OP EOZOON. 151
IS and
icribed
Wales,
er, tlie
fera as
Lmitive
lausted
in tlie
jeeding
. The
forma-
1 deep-
allower
le same
ery dif-
)ssils of
r, while
vidence
ly sedi-
le land,
nes and
Dstones,
xplored
Siluro-
Primor-
'era, the
nknown
auna is
Ige may
tc.
thus bridge over much of the apparent gap in the life
of these two great periods.
Only as yet on the coast of Labrador and neigh-
bouring parts of North Ameiica, and in rocks that
were foT*med in seas that washed the old Laurentian
. ocks, • . hich Eozoon was already as fully sealed up
ab it is at this moment, do we find Protozoa which
can claim any near kinship to the proto-foraminifer.
These are the fossils of the genus Archceocyathus —
"ancient cup-sponges, or cup-foraminifers," which
have been described in much detail by Mr. Billings
in the reports of the Canadian Survey. Mr. Billings
regards them as possibly sponges, or as intermediate
between these and Foraminifera, and the silicious
spicules found in some of them justify this view, un-
less indeed, as partly suspected by Mr. Billings, these
belong to true sponges which may have grown along
with Archaeocyathus or attached to it. Certain it is,
however, that if allied to sponges, they are allied also
to Foraminifera, and that some of them deviate alto-
gether from the sponge type and become calcareous
chambered bodies, the animals of which can have
differed very little f ro/ii those of the Laurentian Eozoon.
It is to these calcareous Foraminiferal species that I
shall at present restrict my attention. I give a few
figures, for which I am indebted to Mr. Billings, of
three of his species (figs. 38 to 40), with enlarged
drawings of the structures of one of them which has
the most decidedly foraminiferal characters.
To understand Archaeocyathus, let us imagine an
152
THE DAWN OP LIFE.
inverted cone of carbonate of lime from an inch or
two to a foot in length, and with its point buried in
the mud at the bottom of the sea, while its open cup
J!
f
:^! ilil
^! I
■I
*'!
Fig. 38. Archaocyathus Mingancnsii—a Primordial Protozoon.
{After Billings.)
(a.) Pores of the inner wall.
extends upward into the water. The lower part
buried in the soil is composed of an irregular acervu-
line network of thick calcareous plates, enclosing
CONTEMPORAEIES AND SUCCESSORS OF EOZOON. 153
Fio. 39. Archccocyathus profundus — shoiving the base of attach-
ment and radiating chambers. {After Billings.)
mmi^
(;
^'C^^
Fig. 40. Archccocyathus Atlanticus — showing outer surface and
longitudinal and transverse sections. {After Billings.)
154
THE DAWN OP LIFE.
1; I
m
!i:;iiH,
chambers communicating witli one another (figs. 40
and 41 a). Above this where the cup expands, its walls
are composed of thin outer and inner plates, perforated
with innumerable holes, and connected with each other
by vertical plates, which are also perforated with round
pores, establishing a communication between the radia-
ting chambers into which they divide the thickness
a
Fig. 41. Structures of Arch<socyathu8 Profundus.
(a.) Lower acervuline portion. (&.) Upper portion, with threo of the radiating
laminae, (c.) Portion of lamina with pores and thickened part with canals.
In figs, a and b the calcareous part is unshaded.
of the wall (figs. 38, 39, and 41 b). In such a struc-
ture the chambers in che wall of the cup and the
irregular chambers of the base would be filled with
gelatinous animal matter, and the pseudopods would
project from the numerous pores in the inner and
outer wall. In the older parts of the skeleton, the
CONTEMPORARIES AND SUCCESSORS OP EOZOON. 155
«■#'
ftfii:'
structure is further complicated by the formation of
thin transverse plates, irregular in distribution, and
where greater strength is required a calcareous thick-
ening is added, which in some places shows a canal
system like that of Eozoon (fig. 41, b, c).^ As com-
pared with Eozoon, the fossils want its fine perforated
wall, but have a more regular plan of growth. There
are fragments in the Eozoon limestones which may
have belonged to structures like these ; and when wo
know more of the deep sea of the Primordial, we may
recover true species of Eozoon from it, or may find
forms intermediate between it and Archseocyathus.
In the meantime I know no nearer bond of connection
between Eozoon and the Primordial age than that
furnished by the ancient cup Zoophytes of Labra-
dor, though I have searched very carefully in the
fossiliferous conglomerates of Cambrian age on the
Lower St. Lawrence, which contain rocks of all the
formations from the, Laurentiau upwards, often with
characteristic fossils. I have also made sections of
many of the fossiliferous pebbles in the.se conglo-
merates without finding any ceitain remains of such
organisms, though the fragments of the crusts of some
of the Primordial tribolites, when their tubuli are in-
filtrated with dark carbonaceous ruatter, are so like
the supplemental skeleton of Eozoon, that but for
* On the whole these curious fossils, if regarded as Fora-
minifera, are most nearly allied to the Orbitolites and Dacty-
loporaB of the Early Tertiary period, as described by Car-
penter,
156
THE DAWN OF LIFE.
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Mil. ... 1 1,.,'i iff.
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their forms tliey might readily be mistaken for it ; and
associated with them are broken pieces of other porous
organisms which may belong to Protozoa, though this
is not yet certain.
Of all the fossils of the Silurian rocks those
which most resemble Eozoon are the Stromatoporce,
or '' layer-corals/' whose resemblance to the old
Laurentian fossil at once struck Sir William Logan ;
and these occur in the earliest great oceanic lime-
stones which succeed the Primordial period, those
of the Trenton group, in the Siluro- Cambrian. From
this they extend upward as far as the Devonian, ap-
pearing everywhere in the limestones, and themselves
often constituting large masses of calcareous rock.
Our figure (fig. 42) shows a small example of one of
these fossils ; and when sawn asunder or broken
across and weathered, they precisely resemble Eozoon
in general appearance, especially when, as sometimes
happens, their cell-walls have been silicified.
There are, however, difi'erent types of these fossils.
Tho most common, the Stromatoporas properly so
called, consist of concentric layers of calcareous matter
attached to each other by pillar-like processes, which,
as well as the layers, are made up of little threads of
limestone netted together, or radiating from the tops
and bottoms of the pillars, and forming a very porous
substance. Though they have been regarded as corals
by some, they are more generally believed to be Proto-
zoa ; but whether more nearly allied to sponges or to
Foraminifera may admit of doubt. Some of the more
CONTEMPORARIES AND SUCCESSORS OP EOZOON. 157
porous kinds are not very dissimilar from calcareous
sponges^ but they generally want true oscula and
pores, and seem better adapted to sliield the gelati-
nous body of a Foraminifer projecting pseudopods in
search of food, than that of a sponge, living by the
Fig. 42. Stromatopora riujosa, Hall — Lower Silurian, Canada.
(After Billings.)
The specimen is of smaller size than usual, and is silicified. It is probably
inverted in position, and the concentric marks on the outer surface ai'e due
to concretions of silica.
introduction of currents of water. Many of the
denser kinds, however, have their calcareous floors so
solid that they must be regarded as much more nearly
akin to Foraminifers, and some of them have the same
irregular inosculation of these floors observed in Eo-
158
THE DAWN OF LIFE.
zoon. Figs. 43, a to d, show portions of species of
tliis description, in whicli the resemblance to Eozoon
in structure and arrangement of parts is not remote.
These fossils, however, show no very distinct canal
'it-
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Fio. 43. Structures of Stromatopora.
(a.) Portion of an oblique section magnified, showing laminae and columns, (ft. )
Portion of wall with pores, and crusted on both sides with quartz crystals.
(c.) Thickened portion of wall with canals. {<!.) Portion of another speci-
men, showing iiregular laminsa and pillars.
system or supplemental skeleton, but this also appears
in those forms which have been called Caunopora or
Coenostroma. In these the plates are traversed by
CONTEMPORARIES AND SUCCESSORS OP EOZOON. 159
tubes, or groups of tubes, which in each successive
floor give out radiating and branching canals exactly-
like those of Eozoon, though more regularly arranged ;
and if we had specimens with the canals infiltrated
with glauconite or serpentine, the resemblance would
be perfect. When, as in figs. 44 and 45 a, these canals
are seen on the abraded surface, they appear as little
grooves arranged in stars, which resemble the radiating
plates of corals, but this resemblance is altogether
superficial, and I have no doubt that they are really
Fig. 44. Caunopora planulata. Hall — Devonian ; showing the radi-
ating canals on a weathered surface. {After Hall.)
|;ppears
)ora or
led. by
foraminiferal organisms. This will appear more dis-
tinctly from the sections in fig. 45 b, c, which repre-
sents an undescribed species recently found by Mr.
Weston, in the Upper Silurian limestone of Ontario.
There are probably many species of these curious
fossils, but their discrimination is difficult, and their
nomenclature confused, so that it would not be profit-
able to engage the attention of the reader with it
except in a note. Their state of preservation, how-
ever, is so highly illustrative of that of Eozoon that a
word as to this will not be out of place. They are
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THE DAWN OF LIFE.
sometimes preserved merely by infiltration with cal-
cite or dolomite, and in tliis case it is most difficult to
make out their minute structures. Often they appear
merely as conoentrically laminated masses which, but
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Fig. 45. Ccenostroma — Guelph Limestone, Upper Silurian, from a
specimen collected by Mr. Weston, showing the canals.
(a.) Surface with canals, natural size, (ft.) Vertical section, natural size, (c.)
The same magnified, showing canals and lanainas.
for their mode of occurrence, might be regarded as
mere concretions. In other cases the cell- walls and
pillars are perfectly silicified, and then they form beau-
tiful microscopic objects, especially when decalcified
with an acid. In still other cases, they are preserved
like Eozoon, the walls being calcareous and the cham-
bers filled with silica. In this state when weathered
or decalcified they are remarkably like Eozoon, but I
have not met with any having their minute pores and
tubes so well preserved as in some of the Laurentian
fossils. In many of them, however, the growth and
overlapping of the successive amoeba-like coats of sar-
code can be beautifully seen, exactly as on the surface
of a decalcified piece of Eozoon. Those in my collec-
tion which most nearly resemble the Laurentian speci-
CONTEMPORARIES AND SUCCESSORS OF EOZOON. 161
I
(c.)
and
mens are from the older part of tlie Lower Silurian
series ; but unfortunately their minute structures are
not well preserved.
In the Silurian and Devonian ages, these Stromato-
porae evidently carried out the same function as the
Eozoon in the Laurentian. Winchell tells us that in
Michigan and Ohio single specimens can be found
several feet in diameter, and that they constitute the
mass of considerable beds of limestone. I have myself
seen in Canada specimens a foot in diameter, with a
great number of laminae. Lindbergh has given a most
vivid account of their occurrence in the Isle of Goth-
land. He says that they form beds of large irregular
discs and balls, attaining a thickness of five Swedish
feet, and traceable for miles along the coast, and the
individual balls are sometimes a yard in diameter. In
some of them the structure is beautifully preserved.
In others, or in parts of them, it is reduced to a mass
of crystalline limestone. This species is of the Coeno-
stroma type, and is regarded by Lindberg as a coral,
though he admits its low type and resemblance to
Protozoa. Its continuous calcareous skeleton he
rightly regards as fatal to its claim to be a true
sponge. Such a fossil, differing as it does in minute
points of structure from Eozoon, is nevertheless proba-
bly allied to it in no very distant way, and a successor
to its limestone-making function. Those which most
nearly approach to Foraminifera are those with thick
and solid calcareous laminae, and with a radiating canal
* Transactions of Swedish Academy, 1870.
162
THE DAWN OF LIFE.
system ; and one of the most Eozoon-like I have seen,
is a specimen of tlie undescribed species already men-
tioned from the Guelph (Upper Silurian) limestone of
Ontario, collected by Mr. Weston, and now in the
Museum of the Geological Survey. I have attempted
to represent its structures in fig. 44.
In the rocks extending from the Lower Silurian and
perhaps from the Upper Cambrian to the Devonian
inclusive, the type and function of Eozoon are con-
tinued by the Stromatopor83, and in the earlier part of
(I
Fig. 46. Beceptaculitet, restored. {After Billings.)
(a.) Aperture. (&.) Inner wall, (c.) Outer wall, (n.) Nucleus, or primary
chamber, (v.) Internal cavity.
this time these are accompanied by the ArchsBo-
cyathids, and by another curious form, more nearly
allied to the latter than to Eozoon, the Recepta-
culites. These curious and beautiful fossils, which
sometimes are a foot in diameter, consist, like Archaeo-
cyathus, of an outer and inner coat enclosing a cavity ;
but these coats are composed of square plates with
CONTEMPOIJARIES AND SUCCESSORS OF EOZOON. 1G3
pores at tlio corners, and tliej are connected by hollow
pillars passing in a regular manner from tlie outer to
Fio. 47. Diagram of Wall and Tubes of Receptaculites. {After
Billings.)
(&.) Inner Mall, (c.) Outer wall, (fi.) Section of plates, (e.) Pore of inner wall.
(/.) Can<il of inner wall, (gr.) Radial stolon, (h.) Cyclical stolon, (k.)
Suture of plates of outer wall.
Fig. 48. Receptaculites, Inner Surface of Outer Wall with the
Stolons remaining on its Surface. {After Billings.)
the inner coat. They have been regarded by Salter as
Foraminifers, while Billings considers their nearest
■a>
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164
THE DAWN OP LIFE.
analogues to be the seed-like germs of some modern
silicious sponges. On the whole, if not Foraminifera,
they must have been organisms intermediate between
these and sponges, and they certainly constitute one of
the most beautiful and complex types of the ancient
Protozoa, showing the wonderful perfection to which
these creatures attained at a very early period. (Figs.
46, 47, 48.)
I might trace these ancient forms of foraminiferal
life further up in the geological series, and show how
in the Carboniferous there are nummulitic shells con-
forming to the general type of Eozoon, and in some
cases making up the mass of great limestones.* Fur-
ther, in the great chalk series and its allied beds, and
in the Lower Tertiary, there are not only vast foramini-
feral limestones, but gigantic species reminding us of
Stromatopora and Eozoon. f Lastly, more diminutive
species are doing similar work on a great scale in the
modern ocean. Thus we may gather up the broktu
links of the chain of foraminiferal life, and affirm that
Eozoon has never wanted some representative to uphold
its family and function throughout all the vast lapse
of geological time.
* FusuUna, as recently described by Carpenter, Archceo-
discus of Brady, and the Nummulite recently found in the
Carboniferous of Belgium.
t Farheria and Loftusia of Carpenter.
CONTEMPORARIES AND SUCCESSORS OP EOZOON. 1 G5
';(;:,
NOTE TO CHAPTER VI.
A. Stromatoporid/e, Etc.
'For the best description of ArchjBocyathus, I may refer to
The Palceozoic Fossils of Canada, by Mr. Billings, vol. i.
There also, and in Mr. Salter's memoir in The Decades of the
Canadian Survey, will be found all that is known of the struc-
ture of Receptaculites. For the American Stromatoporae I
may refer to Winchell's paper in the Proceedings of the
American Association, 1866 ; to Professor Hall's Descriptions
of New Species of Fossils from Iowa, Report of the State
Cabinet, Albany, 1872 ; and to the Descriptions of Canadian
Species by Dr. Nicholson, in his Report on the Palceo7itology
of Ontario, 1874.
The genus Stromatopora of Goldfuss was defined by him as
consisting of laminte of a solid and porous character, alternat-
ing and contiguous, and constituting a hemispherical or sub-
globose mass. In this definition, the porous strata are
really those of the fossil, the alternating solid strata being the
stony filling ol the chambers ; and the descriptions of subse-
quent authors have varied according as, from the state of
preservation of the specimens or other circumstances, the
original laminaB or the filling of the spaces attracted their
attention. In the former case the fossil could be described as
consisting of laminas made up of interlaced fibrils of calcite,
radiating from vertical pillars which connect the laminas. In
the latter case, the laminae appear as solid plates, separated by
very narrow spaces, and perforated with round vertical holes
representing the connecting pillars. These Stromatopora)
range from the Lower Silurian to the Devonian, inclusive, and
many species have been described ; but their limits are not
very definite, though there are undoubtedly remarkable dif-
ferences in the distances of the laminae and in their texture, and
in the smooth or maminillated character of the masses. Hall's
genus Stromatocerium belongs to these forms, and D'Orbigny's
genus Sparsispongia refers to mammillated species, sometimes
with apparent oscula.
166
THE DAWN OP LIFE.
Phillip's genus Caunopora was formed to receive specimens
with concentric cellular layers traversed by "long vermiform
cylindrical canals ;" while Winchell's genus Coenostroma in-
cludes species with these vermiform canals arranged in a radiate
manner, diverging from little eminences in the concentric
lamina3. The distinction between these last genera does not
seem to be very clear, and may depend on the state of preser-
vation of the specimens. A more important distinction
appears to exist between those that have a single vertical canal
from which the subordinate canals diverge, and those that have
groups of such canals.
Some species of the Cosnostroma group have very dense cal-
careous laminae traversed by the canals; but it does not seem
that any distinction has yet been made between the proper
wall and the intermediate skeleton ; and most observers have
been prevented from attending to such structures by the
prevailing idea that these fossils are either corals or sponges,
while the state of preservation of the more delicate tissues is
often very imperfect.
B. Localities of Eozoox, oh of Limestones supposed to
CONTAIN IT.
In Canada the principal localities of Eozoon Canadense are
at Grenville, Petite Nation, the Calumets Eapids, Burgess,
Tudor, and Madoc. At the two last places the fossil occurs in
beds which may be on a somewhat higher horizon i lian the
others. Mr. Vennor has recently found specimens which have
the general form of Eozoon, though the minute structure is not
preserved, at Dalhousie, in Lanark Co., Ontario. One speci-
men from this place is remarkable from having been mineral-
ized in part by a talcose mineral associated with serpentine.
I have examined specimens from Chelmsford, in Massa-
chusetts, and from Amity and Warren County, New York, the
latter from the collection of Professor D. S. Martin, which
show the canals of Eozoon in a fair state of preservation,
though the specimens are fragmental, and do not show the
laminated structure.
CONTEMPORARIES AND SUCCESSORS OP EOZOON. 167
111 European specimens of limestones of Laurentian age,
from Tunaberg and Fahlun in Sweden, and from the Western
Islands of Scotland, I have hitherto failed to recognise the
characteristic structure of the fossil. Connemara specimens
have also failed to afford me any satisfactory results, and
specimens of a serpentine limestone from the Alps, collected
by M. Favre, and communicated to me by Dr. Hunt, though in
general texture they much resemble acervuline Eozoon, do not
show its minute structure?.
i'l'i H
^
Plate VII.
Untouched nature-print of part of a large specimen of Eozoon, from
Petite Nation.
The lighter portions are less perfect than in the original, owing to the finer
laminas of serpentine giving way. The dark band at one side is one of the
deep lacunse or oscula.
m
r
'•-. »
CHAPTER VI r.
OPrONENTS AND OBJECTIONS.
The active objectors to the animal nature of Eozoon
have been few, though some of them have returned to
the attack with a pertinacity and determination which
would lead one to believe that they think the most
sacred interests of science to be dependent on the
annihilation of this proto-foraminifer. I do not pro-
pose here to treat of the objections in detail. I have
presented the case of Eozoon on its own merits, and
on these it must stand. I may merely state that the
objectors strive to account for the existence of Eozoon
by purely mineral deposition, and that the complicated
changes which they require to suppose are perhaps the
strongest indirect evidence for the necessity of regard-
ing the structures as organic. The reader who desires
to appreciate this may consult the notes to this
chapter. * -
I confess that I feel disposed to treat very tenderly
the position of objectors. The facts I have stated
make large demands on the faith of the greater part
even of naturalists. Very few geologists or naturalists
* Also Eowney and King's papers in Journal Geological
Society, August, 1866; and Proceedings Irish Academy, 1870
and 1871.
khi
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170
THE DAWN OF LIFE.
have mucli knowledge of the structure of foramini-
feral shells, or would be able under the microscope to
recognise them with certainty. Nor have they any
distinct ideas of the appearances of such structures
under different kinds of preservation and mineralisa-
tion. Further, they have long been accustomed to
regard the so-called Azoic rocks as not only destitute
of organic remains, but as being in such a state of
metamorphism that these could not have been pre-
served had they existed. Few therefore, are able
intelligently to decide for themselves, and so they are
called on to trust to the investigations of others, and
on their testimony to modify in a marked degree their
previous beliefs as to the duration of life on our planet.
In these circumstances it is rather wonderful that the
researches made with reference to Eozoon have met
with so general acceptance, and that the resurrection
of this ancient inhabitant of the earth has not aroused
more of the sceptical tendency of our age.
It must not be lost sight of, however, that in such
cases there may exist a large amount of undeveloped
and even unconscious scepticism, which shows itself
not in active opposition, but merely in quietly ignoring
this great discovery, or regarding it with doubt, as an
uncertain or unestablished point in science. Such
scepticism may best be met by the plain and simple
statements in the foregoing chapters, and by the illus-
trations accompanying them. It may nevertheless be
profitable to review some of the points referred to, and
to present some considerations making the existence of
OPPONENTS AND OBJECTIONS.
171
Laurentian life less anomalous than may at first sight
be supposed. One of these is the fact that the dis-
covery of Eozoon l;rings the rocks of the Laurentian
system into more full harmony with the other geolo-
gical formations. It explains the origin of the Lau-
rentian limestones in consistency with that of similar
rocks in the later periods, and in like manner it helps
us to account for the graphite and sulphides and iron
ores of these old rocks. It shows us that no time was
lost in the introduction of life on the earth. Otherwise
there would have been a vast lapse of time in which,
while the conditions suitable to life were probably pre-
sent, no living thing existed to take advantage of
these conditions. Further, it gives a more simple
beginning of life than that afforded by the more com-
plex fauna of the Primordial age; and this is more in
accordance with what we know of the slow and gradual
introduction of new forms of living things during the
vast periods of Pala30zoic time. In connection with
this it opens a new and promising field of observation
in the older rocks, and if this should prove fertile, its
exploration may afford a vast harvest of new forms to
the geologists of the present and coming time.
This result will be in entire accordance with what
has taken place before in the history of geological dis-
covery. It is not very long since the old and semi-
metamorphic sediments constituting the great Silurian
and Cambrian systems were massed together in geo-
logical classifications as primitive or primary rocks,
destitute or nearly destitute of organic remains. The
■n
172
THE DAWN OP LIFE.
brilliant discoveries of Sedgwick, Murchison, Barrande,
and a host of others, have peopled these once barren
regions ; and they now stretch before our wondering
gaze in the long vistas of early Palaeozoic life. So
we now look out from the Cambrian shore upon the
vast ocean of the Huronian and Laurentian, all to us
yet tenantless, except for the few organisms, which, Hke
stray shells cast upon the beach, or a far-off land dimly
seen in the distance, incite to further researches, and
to the exploration of the unknown treasures that
still lie undiscovered. It would be a suitable culmina-
tion of the geological work of the last half- century, and
one within reach at least of our immediate successors,
to fill up this great blank, and to trace back the Pri-
mordial life to the stage of Eozoon, and perhaps even
beyond this, to predecessors which may have existed at
the beginning of the Lower Laurentian, when the
earliest sediments of that great formation were laid
down. Vast unexplored areas of Laurentian and Hu-
ronian rocks exist in the Old World and the New. The
most ample facilities for microscopic examination of
rocks may now be obtained ; and I could wish that one
result of the publication of these pages may be to
direct the attention of some of the younger and more
active geologists to these fields of investigation. It is
to be observed also that such regions are among the
richest in useful minerals, and there is no reason why
search for these fossils should not be connected with
other and more practically useful researches. On this
subject it will not be out of place to quote the remarks
OPPONENTS AND OBJECTIONS.
173
which I made in one of my earlier papers on the
Laurentian fossils : —
" This subject opens up several interesting fields of
chemical^ physiological, and geological inquiry. One
of these relates to the conclusions stated by Dr. Hunt
as to the probable existence of a large amount of car-
bonic acid in the Laurentian atmosphere, and of much
carbonate of lime in the seas of that period, and the
possible relation of this to the abundance of certain
low forms of plants and animals. Another is the com-
parison already instituted by Professor Huxley and
Dr. Carpenter, between the conditions of the Lauren-
tian and those of the deeper parts of the modern ocean.
Another is the possible occurrence of other forms of
animal life than Eozoon and Annelids, which I have
stated in my paper of 1864, after extensive microscopic
study of the Laurentian limestones, to be indicated by
the occurrence of calcareous fragments, differing in
structure from Eozoon, but at present of unknown
nature. Another is the effort to bridge over, by
further discoveries similar to that of the Eozoon Ba-
varicum of Giimbel, the gap now existing between the
life of the Lower Laurentian and that of the Prim-
ordial Silurian or Cambrian period. It is scarcely too
much to say that these inquiries open up a new world
of thought and investigation, and hold out the hope of
bringing us into the presence of the actual origin of
organic Ufe on our planet, though this may perhaps be
found to have been Prelaurentian. I would here take
the opportunity of stating that, in proposing the name
174
THE DAWN OF LIFE.
Eozoon for tlio first fossil of tlio Laiirentican, and in
suggesting for tlio period the name " Eozoic," I have
by no means desired to exclude the possibility of forms
of life which may have been precursors of what is now
to us the dawn of organic existence. Should remains
of still older organisms be found in those rocks now
known to us only by pebbles in the Laurentian, these
names will at least serve to mark an important stage
in geological investigation."
But what if the result of such investigations should
be to produce more sceptics, or to bring to light mineral
structures so resembling Eozoon as to throw doubt
upon the whole of the results detailed in these chap-
ters ? I can fancy that this might be the first conse-
quence, more especially if the investigations were in
the hands of persons more conversant with minerals
than with fossils ; but I see no reason to fear the
ultimate results. In any case, no doubt, the value of
the researches hitherto made may be diminished. It
is alwavs the fate of discoverers in Natural Science,
either to be followed by opponents who temporarily or
permanently impugn or destroy the value of their new
facts, or by other investigators who push on the know-
ledge of facts and principles so far beyond their stand-
point that the original discoveries are cast into the
shade. This is a fatality incident to the progress of
scientific work, from which no man can be free ; and in
so far as such matters are concerned, we must all be
content to share the fate of the old fossils whose
history we investigate, and, having served our day and
OPPONENTS AND OBJECTIONS,
geueration to give place to others. If any part of our
work should stand the firo of discussion let us be
thankful. One thing at least is certain, that such
careful surveys as those in the Laurentian rocks of
Canada which led to the discovery of Eozoon, and
such microscopic examinations as those by which it
has been worked up and presented to the public,
cannot fail to yield good results of one kind or
another. Already the attention excited by the con-
troversies about Eozoon, by attracting investigators
to the study of various microscopic and imitative
forms in rocks, has promoted the advancement of
knowledge, and must do so still more. For my own
part, though I am not content to base all my reputa-
tion on such work as I have done with respect to this
old fossil, I am willing at least to take the responsi-
bility of the results I have announced, whatever con-
clusions may be finally reacned ; and in the conscious-
ness of an honest effort to extend the knowledge of
nature, to look forward to a better fame than any
that could result from the most successful and per-
manent vindication of every detail of our scientific
discoveries, even if they could be pushed to a point
which no subsequent investigation in the same difficult
line of research would be able to overpass.
Contenting myself with these general remarks, I
shall, for the benefit of those who relish geological
controversy, append to this chapter a summary of the
objections urged by the most active opponents of the
animal nature of Eozoon, with the replies that may be
ri
176
THE DAWN OF LIFB.
or have been given ; and I now merely add (in fig. 49)
a magnified camera tracing of a portion of a lamina
of Eozoon with it? canals and tubuli, to show more
fully the nature of the structures in controversy.
::i^T^:
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a
~^m^'^
Fig. 49. Portion of a thin Transverse Slice of a Lamina of Eozoon,
magnified, showing its structure, as traced with the camera.
(o.) Nummuline wall of under side, (b.) Intermediate skeleton with canals.
(«'.) Nummnline wall of upper side. The two lower figures show the lower
and upper sides more highly magnified. The specimen is one in which the
canals are unusually well seen.
It may be well, however, to sum up the evidence as
it has been presented by Sir W. E. Logan, Dr. Car-
penter, Dr. Hunt, and the author, in a short and in-
telligible form ; and I shall do so under a few brief
heads, with some explanatory remarks : —
1. The Lower Laurentian of Canada, a rock forma-
OPPONENTS AND OBJECTIONS.
177
49)
rima
Qore
ozoon,
canals.
3 lower
ich the
ce as
Car-
li in-
brief
•rma-
tion whose distribution, uge, and structure have been
thoroughly worked out by the Canadian Survey, is
found to contain thick and widely distributed beds of
limestone, related to the other beds in the same way
in which limestones occur in the sediments of other
geological formations. There also occur in the same
formation, graphite, iron ores, and metallic sulphides,
in such relations as to sug-crest the idea that the lime-
stones as well as these other minerals are of organic
origin.
2. In the limestones are found laminated bodies of
definite form and structure, composed of calcite alter-
nating with serpentine and other minerals. The forms
of these bodies suggested a resemblance to the Si-
lurian Stromatoporae, and the different mineral sub-
stances associated with the calcite in the production
of similar forms, showed that these were not accidental
or concretionary.
3. On microscopic examination, it proved that the
calcareous laminae of these forms were similar in struc-
ture to the shells of modern and fossil Foraminifera,
more especially those of the Rotaline and Nummuline
types, and that the finer structures, though usually
filled with serpentine and other hydrous silicates, were
sometimes occupied with calcite, pyroxene, or dolomite,
showing that they must when recent have been empty
canals and tubes.
4. The mode of filling thus suggested for the cham-
bers and tubes of Eozoon, is precisely that which takes
place in modern Foraminifera filled with glauconite,
N
|y.''!
178
THE DAWN OF LIFE.
: I
and in Palaeozoic crinoids and corals filled with other
hydrous silicates.
5. The type of growth and structure predicated of
Eozoon from the observed appearances, in its great
size, its laminated and acervuline forms, and in its
canal system and tubulation, are not only in con-
formity with those of other Foraminifera, but such as
might be expected in a very ancient form of that
group.
6. Indications exist of other organic bodies in the
limestones containing Eozoon, and also of the Eozoon
being preserved not only in reefs but in drifted frag-
mental beds as in the case of modern corals.
7. Similar organic structures have been found in
the Laurentian limestones of Massachusetts and New
York, and also in those of various parts of Europe,
and Dr. Giimbel has found an additional species in
rocks succeeding the Laurentian in age.
8. The manner in which the structures of Eozoon
are afifected by the faulting, development of crystals,
mineral veins, and other effects of disturbance and
metamorphism in the containing rocks, is precisely
that which might be expected on the supposition that
it is of organic origin.
9. The exertions of several active and able op-
ponents have failed to show how, otherwise than by
organic agency, such structures as those of Eozoon
can be formed, except on the supposition of pseudo-
morphism and replacement, which must be regarded as
chemically extravagant, and which would equally im-
j
OPPONENTS AND OBJECTIONS.
179
pugn tlio validity of all fossils determined by micro-
scopic structure. In like manner all comparisons of
these structures with dendritic and other imitative
forms have signally failed, in the opinion of those best
qualified to judge.
Another and perhaps simpler way of putting the
case is the following : — Only three general modes of
accounting for the existence of Eozoon have been
proposed. The first is that of Professors King and
llowney, who regard the chambers and canals filled
Vrith serpentine as arising from the erosion or partial
dissolving away of serpentine and its replacement by
calcite. The objections to this are conclusive. It
does not explain the nummuline wall, which has to be
separately accounted for by confounding it, contrary
to the observed facts, with the veins of fibrous serpen-
tine which actually pass through cracks in the fossil.
Such replacement is in the highest degree unlikely on
chemical grounds, and there is no evidence of it in the
numerous serpentine grains, nodules, and bands in the
Laurentian limestones. On the other hand, the op-
posite replacement, that of limestone by serpentine,
seems to have occurred. The mechanical difficulties
in accounting for the delicate canals on this theory are
also insurmountable. Finally, it does not account for
the specimens preserved in pyroxene and other sili-
cates, and in dolomite and calcite. A second mode of
accounting for the facts is that the Eozoon forms are
merely peculiar concretions. But this fails to account
for their great difference from the other serpentine
.180
TUE DAWN OF LIFE.
concretions in the same beds, and for their regularity
of plan and the delicacy of their structure, and also
for minerals of different kinds entering into their
composition, and still presenting precisely the same
forms and structures. The only remaining theory is
that of the filling of cavities by infiltration with
serpentine. Tliis accords with the fact that such
infiltration by minerals akin to serpentine exists in
fossils in later rocks. It also accords with the known
aqueous origin of the serpentine nodules and bands,
the veins of fibrous serpentine, and the other minerals
found filling the cavities of Eozoon. Even the pyr-
oxene has been shown by Hunt to exist in the
Laurentian in veins of aqueous origin. The only
difiiculty existing on this view is how a calcite
skeleton with such chambers, canals, and tubuli
could be formed ; and this is solved by the discovery
that all these facts correspond precisely with those to
be found in the shells of modern oceanic Foraminifera.
The existence then of Eozoon, its structure, and its
relations to the containing rocks and minerals being
admitted, no rational explanation of its origin seems
at present possible other than that advocated in the
preceding pages.
If the reader will now turn to Plate VIII., page
207, he will find some interesting illustrations of
several very important facts bearing on the above
arguments. Fig. 1 represents a portion of a very
thin slice of a specimen traversed by veins of fibrous
serpentine or chrysotile, and having the calcite of
OPPONENTS AND OBJECTIONS.
181
the walls raoro broken by cleavage planes than usual.
The portion selected shows a part of one of the
chambers filled with serpentine, which presents the
usual curdled aspect almost impossible to represent
in a drawing (s). It is traversed by a branching
vein of chrysotile (.«?'), which, where cut precisely
parallel to its fibres, shows clear fine cross lineS;
indicating the sides of its constituent prisms, and
where the plane of section has passed obliquely to its
fibres, has a curiously stippled or frowsy appearance.
On either side of the serpentine band is the nummu-
line or proper wall, showing under a low power a
milky appearance, which, with a higher power,
becomes resolved into a tissue of the most beautiful
parallel threads, representing the filling of its tubuli.
Nothing can be more distinct than the appearances
presented by this wall and the chrysotile vein, under
every variety of magnifying power and illumination ;
and all who have had an. opportunity of examining
my specimens have expressed astonishment that ap-
pearances so dissimilar should have been confounded
with each other. On the lower side two indentations
are seen in the proper wall (c). These are connected
with the openings into small subordinate chamberlets,
one jf which is in part included in the thickness of
the slice. At the upper and lower parts of the figure
are seen portions of the intermediate skeleton traversed
by canals, which in the lower part are very large,
though from the analogy of other specimens it is
probable that they have in their interstices minute
182
THE DAWN OP LIFE.
canaliculi not visible in this slice. Fig. 2, from tho
samo specimen, shows tlio termination of one of tho
canals against the proper wall, its end expanding
into a wide disc of sarcode on the sui-face of the wall,
as may be seen in similar structures in modern
Foraminifera. In this specimen the canals are beau-
tifully smooth and cylindrical, but they sometimes
present a knotted or jointed appearance, especially in
specimens decalcified by acids, in which perhaps some
erosion has taken place. They are also occasionally
fringed with minute crystals, especially in those speci-
mens in which tho calcite has been partially replaced
with other minerals. Fig. 3 shows an example of
faulting of the proper wall, an appearance not in-
frequently observed; and it also shows a vein of
chrysotile crossing the line of fault, and not itself
affected by it — a clear evidence of its posterior origin.
Figs. 4 and 5 are examples of specimens having
the canals filled with dolomite, and showing ex-
tremely fine canals in tho interstices of the others :
an appearance observed only in the thicker parts of
the skeleton, and when these are very well preserved.
These dolomitized portions require some precautions
for their observation, either in slices or decalcified
specimens, but when properly managed they show
the structures in very great perfection. The, speci-
men in fig. 5 is from an abnormally thick portion of
intermediate skeleton, having unusually thick canali?,
and referred to in a previous chapter.
One object which I have in view in thus minutely
OPPONENTS AND OBJECTIONS.
183
dlroctinf^ attention to these illustrations, is to show
the nature of the misapprehensions which may occur
in examining specimens of this kind, and at the same
time the certainty which may bo attained when proper
precautions are taken. I may add that such struc-
tures as those referred to are best seen in ex-
tremely thin slices, and that tlio observer must not
expect that every specimen will exhibit them equally
well. It is only by preparing and examining many
specimens that the best results can be obtained. It
often happens that one specimen is required to show
well one part of the structures, and a different one
to show another; and previous to actual trial, it is
not easy to say which portion of the structures any
particular fragment will show most clearly. This
renders it somewhat difficult to supply one's friends
with specimens. Really good slices can be prepared
only from the best material and by skilled manipu-
lators ; imperfect slices may only mislead ; and rough
specimens may not be properly prepared by persons
unaccustomed to the work, or if so prepared may
not turn cut satisfactory, or may not be skilfully
examined. These difficulties, however, Eozoon shares
with other specimens in micro-geology, and I have
experienced similar disappointments in the case of
fossil wood.
In conclusion of this part of the subject, and
referring to the notes appended to this chapter for
further details, I would express the hope that those
who have hitherto opposed the interpretation of Eozoon
ill!
All
18A
THE DAWN OF LIFE.
as organic, and to wliose ability and honesty of
purpose I willingly bear testimony, will find them-
selves enabled to acknowledge at least the reasonable
probability of that interpretation of these remarkable
Ibrms and structures.
NOTES TO CHAPTER VII.
A. Objections or Profs. King and Rowney.
Trans. Royal Irish Academy, July, 18G9.*
The following summary, given by these authors, may be
taken as including the substance of their objections to the
animal nature of Eozoon. I shall give them in their words
and follow them with short answers to each.
" 1st. The serpentine in ophitic rocks has been shown to
present appearances which can only be explained on the view
that it undergoes structural and chemical changes, causing it
to pass into variously subdivided states, and etching out the
resulting portions into a variety of forms — grains and plates,
with lobulated or segmented surfaces — fibres and aciculi —
simple and branching configurations. Crystals of malacolite,
often associated with the serpentine, manifest some of these
changes in a remarkable degree.
" 2nd. The ' intermediate skeleton ' of Eozoon (which we
hold to be the calcareous matrix of the above lobulated
grains, etc.) is completely paralleled in various crystalline
rocks — notably marble containing grains of coccolite (Aker
and Tyree), pargasite (Finland), chondrodite (New Jersey, etc.).
" 3rd. The ' chamber casts ' in the acervuline variety of
Eozoon are more or less paralleled by the grains of the
mineral silicates in the pre-cited marbles.
Reprinted in the Annals and Magazine of Natural History, May,
:87i.
OPPONENTS AND OBJECTIONS.
185
" 4tli. The 'chamber casts* being composed occasionally of
loganite and malacolite, besides serpentine, is a fact which,
instead of favouring their organic origin, as supposed, musn
be held as a proof of their having been produced by mineral
agencies ; inasmuch as these three silicates have a close
pseudomorphic relationship, and may therefore replace one
another in their naturally prescribed order.
"5th. Dr. GUmbel, observing rounded, cylindrical, ortuber-
culated grains of coccolite and pargasite in crystalline cal-
careous marbles, considered them to be 'chamber casts,' or
of organic origin. We have shown that such grains often
present crystalline planes, angles, and edges ; a fact clearly
proving that they were originally simple or compound crystals
that have undergone external decretion by chemical or solvent
action.
" 6th. We have adduced evidences to show that the ' nummu-
line layer' iu its typical condition — that is, consisting of
cylindrical aciculi, separated by interspaces filled with calcite
— has originated diroctly from closely packed fibres ; these
from chrysotile or asbestiform serpentine; this from in-
cipiently fibrous serpentin^^ ; and the latter from the same
mineral in its amorphous or sti'uctureless condition.
"7th. The 'nummuline layer,' In its typical condition, un-
mistakably occurs in cracks or fissures, both in Canadian and
Connemara ophite.
" 8th. The ' nummuline layer ' is parall-^led by the fibrous
coat which is occasionally present on the surface of grains of
chondrodite.
" 9th. We have shown that the relative position of two super-
posed asbestiform layers (an ujjper and an binder ' proper
wall'), and the admitted fact of their component aciculi
often passing continuously and without interruption from one
'chamber cast' to another, to the exclusion of the 'inter-
mediate skeleton,' are totally incompatible with the idea of
the 'nummuline layer' having resulted from pseudopodial
tubulation.
" 10th. The so-called ' stolons ' and ' passages of communi-
cation exactly corresponding with those described in Cyclo-
w
18(5
THE DAWN or LIFE.
i
r.hipeiis,* have been shown to be tabular crystals and variously
formed bodies, belonging to different minerals, wedged cros>-
ways or obliquely in the calcareous interspaces between the
grains and plates of serpentine.
" 11th. The ' canal system ' is composed of serpentine, or
malacolite. Its typical kinds in the first of these minerals
may be traced in all stages of formation out of plates, prisms,
and other solids, undergoing a process of superficial decretion.
Those in malacolite are made up of crystals — single, or aggre-
gated together — that have had their planes, angles, and edges
rounded off; or have become further reduced by some solvent.
"12th. The 'canal system' in its remarkable branching
varieties is completely paralleled by crystalline configurations
in the coccolite marble of Aker, in Sweden; and in the
crevices of a crystal of spinel imbedded in a calcitic matrix
from Amity, New York.
"13th. The configurations, presumed to represent the 'canal
systems,' ai'e totally without any regularity of form, of relative
size, or of arrangement ; and they occur independently of and
apart from other * eozoonal features ' (Amity, Boden, etc.) ;
facts not only demonstrating them to be purely mineral
products, but which strike at the root of the idea that they are
of organic origin.
" 14th. In answer to the argument that as all the foregoing
' eozoonal features ' are occasionally found together in ophite,
the combination must be considered a conclusive evidence of
their organic origin, we have shown, from the composition,
physical characters, and circumstances of occurrence and
association of their component serpentine, that they represent,
the structural and chemical changes which are eminently and
peculiarly characteristic of this mineral. It has also been
shown that the combination is paralleled to a remarkable
extent in chondrodite and its calcitic matrix.
" 15th. The * regular alternation of lamellas of calcareous and
silicious minerals ' (respectively representing the * inter-
mediate skeleton ' and ' chamber casts ') occasionally seen in
ophite, and considered to be a * fundamental fact ' evidencing
an organic arrangement, is proved to be a mineralogical
OPPONENTS AND OBJECTIONS.
187
phenomenon by the fact that a similar alternation occurs in
amphiboline-calcitic marbles, and gneissose rocks.
"16th. In order to account for certain im/oiyar^ difficulties
presented by the configurations forming the 'canal system,'
and the aciculi of the ' nummuline layer' — that is, when they
occur as 'solid Jmndles^ — or are 'closely packed' — or 'appear
to he glued together ' — Dr. Carpenter has proposed the theory
that the sarcodic extensions which they are presumed to re-
present have been * turned into stone' (a ' silicious mineral')
'by Nature's cunning' ('just as the sarcodic layer on the
surface of the shell of living Foraminifers is formed by the
spreading out of coalesced bundles of the pseudopodia that
have emerged from the chamber wall') — * by a process of
chemical substitution before their destruction by ordinary
decomposition.' We showed this quasi-alchymical theory to
be altogether unscientific.
"17th. The 'silicious mineral ' (serpentine) has been ana-
logued with those forming the variously-formed casts (i?i
' glauconite,' etc.) of recent and fossil Foraminifers. We havo
shown that the mineral silicates of Eozoon have no relation
whatever to the substances composing such casts.
"18th. Dr. Hunt, in order to account for the serpentine,
loganite, and malacolite, being the presumed in-filling sub-
stances of Eozoon, has conceived tlie ' novel doctrine,' that
such minerals were directly deposited in the ocean waters in
which this * fossil ' lived. We have gone over all his evidences
and arguments without finding one to be substantiated.
"19th. Having investigated the alleged cases of ' chambers '
and * tubes ' occurring * filled with calcite,' and presumed to
be * a conclusive answer to ' our * objections,' we have showfi
that there are the strongest grounds for removing them from
the category of reliable evidences on the side of the organi<!
doctrine. The Tudor specimen has been shown to be equally
unavailable.
*'' 20th. The occurrence of the best preserved specimens of
Eozoon Canadenso in rocks that are in a ' highly crystalline
condition* (Dawson) must bo accepted as a fact utterly fatal
to its organic origin.
188
THE DAWN OF LIFE.
«<oi
21st. The occurrence of * eozoonal features' solely in crystal-
line or metamorphosed rocks, belonging to the Laurentian,
the Lower Silurian, and the Liassic systems — never in ordinary
unaltered deposits of these and the intermediate systems-
must be assumed as completely demonstrating their purely
mineral origin."
The answers already given to these objections may be
summed up severally as follows : —
1st. This is a mere hypothesis to account for the forms pre-
sented by serpentine grains and by Eozoon. Hunt has shown
that it is untenable chemically, and has completely exploded it
in his recent papers on Chemistry and Geology.* My own
observations show that it does not acccord with the mode of
occurrence of serpentine in the Laurentian limestones of
Canada.
2nd. Some of the things stated to parallel the intermediate
skeleton of Eozoon, are probably themselves examples of that
skeleton. Others have been shown to have no resemblance
to it.
8rd. The words "more or less " indicate the precise value of
this statement, in a question of comparison between mineral
and organic structures. So the prismatic structure of satin-
spar may be said " more or less " to resemble that of a shell,
or of the cells of a Stenopora.
4th. This overlooks the filling of chamber casts with py-
roxene, dolomite, or limestone. Even in the case of logauite
this objection is of no value unless it can be applied equally
to the similar silicates which fill cavities of fossils f in the
Silurian limestones and in the grecnsand.
5th. Dr. Giimbel's observations are those of a highly skilled
and accurate observer. Even if crystalline forms appear in
" chamber casts," this is as likely to be a result of the injury
of organic structures by crystallization, as of the partial eiface-
ment of crystals by other actions. Crystalline faces occur
abundantly in many undoubted fossil woods and corals ; and
* Boston, 1874. a
t See for a full discussion of this subject Dr. Hunt's '• Papers "
above referred to.
crystal-
rentian,
rdinary
items —
purely
may be
ms pre-
3 shown
loded ib
^y own
mode of
lones of
mediate
I of that-
mblance
value of
mineral
of satin-
a shell,
vith py-
logauite
I equally
f in the
y skilled
ppear in
le injury
al efface-
jes occur
als ; and
♦ Papers "
OPPONENTS AND OBJECTIONS.
189
crystals not unfrequently cross and interfere with the struc-
tures in such specimens.
6th. On the contrary, the Canadian specimens prove clearly
that the veins of chrysotile have been filled subsequently to
the existence of Eozoon in its present state, and that there is
no connection whatever between them and the Nummuline
wall.
7th. This I have never seen in all my examinations of
Eozoon. The writers must have mistaken veins of fibrous ser-
pentine for the nummuline wall.
8th. Only if such grains of chondrodite are themselves
casts of foraminiferal chambers. But Messrs. King and
E-owney have repeatedly figured mere groups of crystals as
examples of the nummuline wall,
9th. Dr. Carpenter has shown that this objection depends
on a misconception of the structure of modern Foraminifera,
which show similar appearances.
10th. That disseminated crystals occur in the Eozoon lime-
stones is a familiar fact, and one paralleled in many other
more or less altered organic limestones. Foreign bodies also
occur in the chambers filled with loganite and other minerals ;
but these need not any more be confounded with the pillars
and walls connecting the laminae than the sand filling a dead
coral with its lamellae. Further, it is well known that foreign
bodies are often contained both in the testa and chambers even
of recent Foraminifera.
11th. The canal system is not always filled with serpentine
or malacolite ; and when filled with pyroxene, dolomite, or
calcite, the forms are the same. The irregularities spoken of
are perhaps more manifest in the serpentine specimens,
because this mineral has in places encroached on or partially
replaced the calcite walls.
12th. If this is true of the Aker marble, then it must con-
tain Eozoon; and specimens of the Amity limestone which
I have examined, certainly contain largo fragments of Eo-
zoon.
13th. The configuration of the canal system is quite
definite, though varying in coarseness and fineness. It is
190
THE DAWN OF LIFE.
iiiii
iMii
not known to occur independently of the forms of Eozoon
except in fragmental deposits.
14th. The argument is nob that they are "occasionally found
together in ophite," but that they are found together in speci-
mens preserved by different minerals, and in such a way as to
show that all these minerals have filled chambers, canals, and
tubuli, previously existing in a skeleton of limestone.
15th. The lamination of Eozoon is not like that of any rock,
but a strictly limited and definite form, comparable with that
of Stromatopora.
16th. This I pass over, as a mere captious criticism of modes
of expression used by Dr. Carpenter.
17th. Dr. Hunt, whose knowledge of chemical geology
should give the greatest weight to his judgment, maintains
the deposition of serpentine and loganite to have taken place
in a manner similar to that of joUyte and glauconite in un-
doubted fossils: and this would seem to be a clear deduction
from the facts he has stated, and from the chemical character
of the substances. My own observations of the mode of oc-
currence of serpentine in the Eozoon limestones lead me to
the same result.
18th. Dr. Hunt's arguments on the subject, as recently
presented in his Papers on Chemistry and Geology, need
only be studied by any candid and competent chemist or
mineralogist to lead to a very different conclusion from that of
the objectors.
19th. This is a mere statement of opinion. The fact re-
mains that the chambers and canals are sometimes filled with
calcite.
20th. That the occurrence of Eozoon in crystalline lime-
stones is " utterly fatal " to its claims to organic origin can be
held only by those who are utterly ignorant of the frequency
with which organic remains are preserved in highly crystal-
line limestones of all ages. In addition to other examples
mentioned above, I may state that the curious specimen of
Coenostroma from the Gnelph limestone figured in Chapter VI.,
has been converted into a perfectly crystalline dolomite, while
its canals and cavities have been filled with calcite, since
weathered out.
iozoon
;eology
OPPONKNTS A\D OBJECTIONS.
191
21st. This limited occurrence is an assumption contrary to
facts. It leaves out of account the Tudor specimens, and also
the abundant occurrence of the Stromatoporoid successors of
Eozoon in the Silurian and Devonian. Further, even if the
Eozoon were limited to the Laurentian, this would not be
remarkable; and since all the Laurentian rocks known to us
are more or less altered, ib could not in that case occur in
unaltered rocks.
I have gone over these objections seriatim, because, though
individually weak, they have an imposing appearance in
the aggregate, and have been paraded as a conclusive settle-
ment of the questions at issue. They have even been re-
printed in the year just past in an English journal of some
standing, which professes to accept only original contributions
to science, but has deviated from its rule in their favour. I
may be excused for adding a portion of my original argument
in opposition to these objections, as given more at length iu
the Transactions of the Irish Academy.
1. I object to the authors' mode of stating the question at
issue, whereby they convey to the reader the impression that
this is merely to account for the occurrence of certain peculiar
forms in ophite.
With reference to this, it is to be observed that the attention
of Sir William Logan, and of the writer, was first called to
Eozoon by the occurrence in Laurentian rocks of definite
forms resembling the Silurian Stromatoporoi, and dissimilar
from any concretions or crystalline structures found in these
rocks. With his usual sagacity, Sir William added to these
facts the consideration that the mineral substances occurring
in these forms were so dissimilar as to suggest that the forms
themselves must be due to some extraneous cause rather than
to any crystalline or segregative tendency of their constituent
minerals. These specimens, which were exhibited by Sir
William as probably fossils, at the meeting of the American
Association in 1859, and noticed with figures in the Keport of
the Canadian Survey for 1863, showed under the microscope
no minute structures. The writer, who had at the time an
opportunity of examining them, stated his belief that if fossils,
they would prove to be not Corals but Protozoa.
ilSl'^'
192
THE DAWN OF LIFE.
In 1864, additional specimens having been obtained by tho
Survey, slices were submitted to the writer, in which he at
once detected a well-marked canal-system, and stated, de-
cidedly, his belief that the forms were organic and fora-
minifcral. The announcement of this discovery was first made
by Sir "VV. E. Logan, in Silliman's Journal for 1864. So far,
the facts obtained and stated related to definite forms mineral-
ised by loganite, serpentine, pyroxene, dolomite, and calcite.
But before publishing these facts in detail, extensive series of
sections of all the Laurentian limestones, and of those of the
altered Quebec group of the Green Mountain range, were made,
under the direction of Sir W. E. Logan and Dr. Hunt, and
examined microscopically. Specimens were also decalcified by
acids, and subjected to chemical examination by Dr. Sterry
Hunt. The result was the conviction that the definite lami-
nated forms must be organic, and further, that there exist in
the Laurentian limestones fragments of such forms retaining
their structure, and also other fragments, probably organic,
but distinct from Eozoon. These conclusions were submitted
to the Geological Society of London, in 1864, after the speci-
mens on which they were based had been shown to Dr. Car-
penter and Professor T. E. Jones, the former of whom detected
in some of the specimens an additional foraminiferal structure
— that of the tubulation of the proper wall, which I had not
been able to make out. Subsequently, in rocks at Tudor, of
somewhat later age than those of the Lower Laurentian at
Grenville, similar structures were found in limestones not more
metamorphic than many of those which retain fossils in the
Silurian system. I make this historical statement in order to
place the question in its true light, and to show that it relates
to the organic origin of certain definite mineral masses, ex-
hibiting, not only the external forms of fossils, but also their
internal structure.
In opposition to these facts, and to the careful deductions
drawn from them, the authors of the paper under considera-
tion maintain that the structures are mineral and crystalline.
I believe that in the present state of science such an attempt
to return to the doctrine of "plastic-force" as a mode of
I li ;
OPPONENTS AND OBJECTIONS.
193
accounting for fossils would not be tolerated for a moment,
were it not for the great antiquity and highly crystalline con-
dition of the rocks in which the structures are found, which
naturally create a prejudice against the idea of their being
fossiliferous. That the authors themselves feel this is apparent
from the slight manner in which they state the leading facts
above given, and from their evident anxiety to restrict the
question to the mode of occurrence of serpentine in limestone,
and to ignore the specimens of Eozoon preserved under
different mineral conditions.
2. With reference to the general form of Eozoon and its
structure on the large scale, I would call attention to two
admissions of the authors of the paper, which appear to me to
be fatal to their case : — First, they admit, at page 533 [Pro-
ceedings, vol. X.], their " inability to explain satisfactorily "
the alternating layers of carbonate of lime and other minerals
in the typical specimens of Canadian Eozoon. They make a
feeble attempt to establish an analogy between this and
certain concentric concretionary layers; but the cases are
clearly not parallel, and the laminae of the Canadian Eozoon
present connecting plates and columns not explicable on any
concretionary hypothesis. If, however, they are unable to
explain the lamellar structure alone, as it appeared to Logan
in 1859, is it not rash to attempt to explain it away now, when
certain minute internal structures, corresponding to what
might have been expected on the hypothesis of its organic
origin, are added to it ? If I affirm that a certain mass is the
trunk of a fossil tree, and another asserts that it is a concretion,
but professes to be unable to account for its form and its rings
of growth, surely his case becomes very weak after I have
made a slice of it, and have shown that it retains the structure
of wood.
Next, they appear to admit that if specimens occur wholly
composed of carbonate of lime, their theory will fall to the
ground. Now such specimens do exist. They treat the Tudor
specimen with scepticism as probably " strings of segregated
calcite." Since the account of that specimen was published,
additional fragments have been collected, so that new slices
O
JT
i;iji!l:ni 1
I 1 I
I.
i ai\
194
THE DAWN OF LIFE.
have been prepared. I have examined these with care, and
am prepared to aflBrm that the chambers in these specimens
are filled with a dark-coloured limestone not more crystalline
than is usual in the Silurian rocks, and that the chamber-
walls are composed of carbonate of lime, with the canals filled
with the same material, except where the limestone filling the
chambers has penetrated into parts of the larger ones. I
should add that the stratigraphical researches of Mr. Vennor,
of the Canadian Survey, have rendered it probable that the
beds containing these fossils, though unconformably under-
lying the Lower Silurian, overlie the Lower Laureutian of the
locality, and are, therefore, probably Upper Laurentian, or
perhaps Huronian, so that the Tudor specimens may approach
in age to Giimbel's Eozoon Bavaricum.*
Further, the authors of the paper have no right to object to
our regarding the laminated specimen as *' typical " Eozoon.
If the question were as to typical ophite the case would be
different ; but the question actually is as to certain well-defined
forms which we regard as fossils, and allege to have organic
structure on the small scale, as well as lamination on the large
scale. "We profess to account for the acervuline forms by the
irregular growth at the surface of the organisms, and by the
breaking of them into fragments confusedly intermingled in
great thicknesses of limestone, just as fragments of corals
occur in Palaeozoic limestones ; but we are under no obligation
to accept irregular or disintegrated specimens as typical ; and
when objectors reason from these fragments, we have a right
to point to the more perfect exam^)les. It would be easy to
explain the loose cells of Tetradium which characterize the
bird's-eye limestone of the Lower Silurian of America, as
crystalline structures; but a comparison with the unbroken
masses of the same coral, shows their true nature. I have for
some time made the minute structure of Palaeozoic limestones
• I may now refer in addition to the canals filled with calcite and
dolomite, detected by Dr. Carpenter and myself in specimens from
Petite Nation, and mentioned in a previous chapter. See also
Plate VIIL
OPPONENTS AND OBJECTIONS.
105
care, and
pocimous
rystallino
cbamber-
lals filled
lUing the
ones. I
. Vennor,
that tho
y under-
lan of the
(ntian, or
approach
object to
' Eozoou.
would be
ill-defined
e organic
the large
IS by the
d by the
ingled in
of corals
)bligation
ical; and
^e a right
e easy to
;erize the
lerica, as
unbroken
[ have for
imestones
lalcite and
Bens from
See also
a special study, and have described some of them from the
Silurian formv. Lions of Canada.* I possess now many ad-
ditional examples, showing fragments of various kinds of
fossils preserved in these limestones, and recognisable only by
the infiltration of their pores with different silicious minerals.
It can also be shown that in many cases the crystallization
of the carbonate of lime, both of the fossils themselves and
of their matrix, has not interfered with the perfection of the
most minute of these structures.
The fact that the chambers arc usually filled with silicates is
strangely regarded by the authors as an argument against the
organic nature of Eozoon. One would think that the extreme
frequency of silicious fillings of the cavities of fossils, and
even of silicious replacement of their tissues, should have
prevented the use of such an argument, without taking into
account the opposite conclusions to be drawn from the various
kinds of silicates found in the specimens, and from the modem
tilling of Foraminifera by hydrous silicates, as shown by
Ehrenberg, Mantell, Carpenter, Bailey, and Pourtales.f
Further, I have elsewhere shown that the loganite is proved
by its texture to have been a fragmental substance, or at least
filled with loose debris ; that the Tudor specimens have the
cavities filled with a sedimentary limestone, and that several
fragmental specimens from Madoc are actually wholly cal-
careous. It is to be observed, however, that the wholly
calcareous specimens present great difficulties to an observer;
and I have no doubt that they are usually overlooked by col-
lectors in consequence of their not being developed by weather-
ing, or showing any obvious structure in fresh fractures.
3. With regard to the canal system, the authors persist in
confusing the casts of it which occur in serpentine with
" metaxite " concretions, and in likening them to dendritic
crystallizations of silver, etc., and coralloidal forms of carbonate
of Ume. In answer to this, I think it quite sufficient to say
that I fail to perceive the resemblance as other than very
* In the Canadian Naturalist.
t Quarterly Journal Geol. Society, 1864.
M
■rMs,
11
'n
■: I
{ 1
I
m
190
THE DAWN OP LIFE.
imperfectly imitative. I may add, that the case is one of the
occurrence of a canal structure in forms which on other
grounds appear to be organic, while the concretionary forma
referred to are produced under diverse conditions, none of them
similar to those of which evidence appears in the specimens of
Eozoon. With the singular theory of pseudomorphism, by
means of which the authors now supplement their previous
objections, I leave Dr. Hunt to deal.
4. With respect to the proper wall and its minute tubulation,
the essential error of the authors consists in confounding it
with fibrous and acicular crystals, and in maintaining that
because the t.^buli are sometimes apparently confused and con-
fluent they must be inorganic. With regard to the first of these
positions, I may repeat what I have stated in former papers —
that the true cell-wall presents minute cylindrical processes
traversing carbonate of lime, and usually nearly parallel to
each other, and often slightly bulbose at the extremity.
Fibrous serpentine, on the other hand, appears as angular
crystak, closely packed together, while the numerous spicular
crystals of silicious minerals which ofter appear in metamorphic
limestones, and may be developed by decalcification, appear
sa sharp angular needles usually radiating from centres or
irregularly disposed. Their own plate (Ophite from Skye,
King and Eowney's Paper, Froc. B. I. A., vol. x.), is an
eminent example of this; and whatever the nature of the
crystals represented, they have no appearance of being true
tubuli of Eozoon. I have very often shown microscopists and
geologists the cell-wall along with veins of chrysotile and
coatings of acicular crystals occurring in the same or similar
limestones, and they have never failed at once to recognise the
difference, especially under high powers.
I do not deny that the tubulation is often imperfectly pre-
served, and that in such cases the casts of the tubuli may
appear to be glued together by concretions of mineral matter,
or to be broken or imperfect. But this occurs in all fossils,
and is familiar to any microscopist examining them. How
difficult is it in many cases to detect the minute structure of
Nummulites and other fossil Foraminifera P How often does
mo of the
on other
ivy forms
le of them
cimens of
)hism, by
' previous
ubulation,
)unding it
ning that
1 and con-
st of these
• papers —
processes
)arallel to
extremity.
g angular
IS spicular
iamorphic
m, appear
jentres or
om Skye,
x.)» is an
iro of the
leing true
opists and
3otile and
or similar
ognise the
Pectly pre-
abuli may
•al matter,
all fossils,
3m. How
nicture of
)ften does
.OPPONENTS AND OBJECTIONS.
197
a specimen of fossil wood present in one part distorted and
confused fibres or mere crystals, with the remains of the wood
forming phragmata between them, when in other parts it may
show the most minute structures in perfect preservation P
But who would use the disintegrated portions to invalidate
the evidence of the parts better preserved? Yet this is
precisely the argument of Professors King and Rowney, and
which they have not hesitated in using in the case of a fossil
80 old as Eozoon, and so often compressed, crushed, and partly
destroyed by mineralization.
I have in the above remarks confined myself to what I
regard as absolutely essential by way of explanation and
defence of the organic nauure of Eozoon. It would bo un-
profitable to enter into the multitude of subordinate points
raised by the authors, and their theory of mineral pseudo-
morphism is discussed by my friend Dr. Hunt ; but I must
say here that this theory ought, in my opinion, to afford to
any chemist a strong presumption against the validity of their
objections, especially since it confessedly does not account for
all the facts, while requiring a most complicated serioi of
unproved and improbable suppositions.
The only other new features in t^ communication to which
this note refers are contained in " supplementary note."
The first of these relates to the gr^.iis of coccolite in the lime-
stone of Aker, in Sweden. Whether or not these are organic,
they are apparently different from Eozoon Canadense. They,
no doubt, resemble the grains referred to by Giimbel as
possibly organic, and also similar granular objects with pro-
jections which, in a previous paper, I have described from
Laurentian limestones in Canada. These objects are of
doubtful nature ; but if organic, ^dy are distinct from
Eozoon. The second relates to the supposed crystals of
malacolite from the same place. Admitting the interpretation
given of these to be correct, they are no more related to
Eozoon than are the curious vermicular crystals of a micaceous
mineral which I have noticed in the Canadian limestones.
The third and still more remarkable case is that of a spinel
from Amity, New York, containing calcite in its crevices.
i
193
THE DAWN OP LIFE.
Mi ■
including a perfect canal system preserved in malacolite.
With reference to this, as spinels of lar^e size occur in veins
in the Laurentian rocks, I am not prepared to say that it is
absolutely impossible that fragments of limestone containing
Eozoon may not be occasionally associated with them in their
matrix. I confess, however, that until I can examine such
specimens, which I have not yet met with, I cannot, after my
experience of the tendencies of Messrs. Rowney and King to
confound other forma with those of Eozoon, accept their
determinations in a matter so critical and in a case so
unlikely.*
If all specimens of Eozoon were of the acervuline character,
the comparison of the chamber-casts with concretionary
granules might have some plausibility. But it is to be ob-
served that the laminated arrangement is the typical one ; and
the study of the larger specimens, cut under the direction of
Sir W. E. Logan, shows that these laminated forms must have
grown on certain strata-planes before the deposition of the
overlying beds, and that the beds are, in part, composed of the
broken fragments of similar laminated structures. Further,
much of the apparently acervuline Eozoon rock is composed of
such broken fragments, the interstices between which should
not be confounded with the chambers : while the fact that the
serpentine fills such interstices as well as the chambers shows
that its arrangement is not concretionary. Again, these
chambers are filled in different specimens with serpentine,
pyroxene, loganite, calcareous spar, chondrodite, or even with
arenaceous limestone. It is also to be observed that the examin-
ation of a number of limestones, other than Canadian, by
Messrs. King and Rowney, has obliged them to admit that the
laminated forms in combination with the canal-system are
" essentially Canadian," and that the only instances of struc-
tures clearly resembling the Canadian specimens are afforded
* I have since ascertained that Laurentian limestone found at
Amity, New York, and containing spinels, does hold fragments of the
intermediate slceleton of Eozoon. The limestone may have been
originally a mass of fragments of this kind with the aluminous and
magnesian material of the spinel in their interstices.
OPPONENTS AND OBJECTIONS.
190
lalacolite.
r in veins
that it is
ontaining
1 in their
line such
after my
King to
ept their
case so
by limestones Laurentian in age, and in some of ^which (as, for
instance, in those of Bavaria and Scandinavia) Carpenter and
Giimbel have actually found the structure of Eozoon. The
other serpentine-limestones examined (for example, that of
Skye) are admitted to fail in essential points of structure ; and
the only serpentine believed to be of eruptive origin examined
by them is confessedly destitute of all semblance of Eozoon.
Similar results have been attained by the more careful re-
searches of Prof. Giimbel, whose paper is well deserving of
study by all who have any doubts on this subject.
jharacter,
retionary
to be ob-
one; and
•ection of
lust have
>n of the
;ed of the
Further,
iposed of
!h should
that the
rs shows
m, these
rpentine,
ven with
) examin-
iian, by
that the
stem are
of struc-
afforded
found at
ats of the
ave been
nous and
B. Reply by Dr. Hunt to Ciiemica.l Objections— (J5i(?.).
" In the Proceedings of the Boyal Irish Academy, for July
12, 1869, Messrs. King and Rowney have given us at length
their latest corrected views on various questions connected
with Eozoon Canadense. Leaving to my friend, Dr. Dawson,
the discussion of the zoological aspects of the question, I can-
not forbear making a few criticisms on the chemical and mine-
ral ogical views of the authors. The problem which they had
before them was to explain the occurrence of certain forms
which, to skilled observers, like Carpenter, Dawson, and
Rupert Jones, appear to possess all the structural character of
the calcareous skeleton of a foraminiferal organism, and more-
over to show how it happens that these forms of crystalline
carbonate of lime are associated with serpentine in such a way
as to lead these observers to conclude that this hydrous silicate
of magnesia filled and enveloped the calcareous skeleton, re-
plucing the perishable sarcode. The hypothesis now put for-
ward by Messrs. King and Rowney to explain the appearances
in q^iestion, is, that all this curiously arranged serpentine,
which appears to be a cast of the interior of a complex forami-
niferal organism, has been shaped or sculptured out of plates,
prisms, and other solids of serpentine, by " the erosion and
incomplete waste of the latter, the definite shapes being residual
portions of the solid that have not completely disappeared."
The calcite which limits these definite shapes, or, in other
words, what is regarded as the calcareous skeleton of Eozoon,
200
THE DAWN OF LIFE.
1
is a ' replacement pseudomorph ' of calcite taking the place of
the wasted and eroded serpentine. It was not a calcareous
fossil, filled and surrounded by the serpentine, but was formed
in the midst of the serpec^'ae itself, by a mysterious agency
which dissolved away this leral to form a mould, in which
the calcite was cast. This marvellous process can only be
paralleled by the operations of that plastic force in virtue of
which sea-shells were supposed by some old naturalists to be
generated in the midst of rocky strata. Such equivocally
formed fossils, whether oysters or Foraminifers, may well be
termed pseudormorphs, but we are at a loss to see with what
propriety the authors of this singular hypothesis invoke the
doctrines of mineral pseudormorphism, as taught by Rose,
Blum, Bischof, and Dana. In replacement pseudomorphs, as
understood by these authors, a mineral species disappears and
is replaced by another which retains the external form of the
first. Could it be shown that the calcite of the cell-wall of
Eozoon was once serpentine, this portion of carbonate of lime
would be a replacement pseudomorph after serpentine ; but
why the portions of this mineral, which on the hypothesis of
Messrs. King and Rowney have been thus replaced, should
assume the forms of a foraminiferal skeleton, is precisely what
our authors fail to show, and, as all must see, is the gist of the
whole matter.
" Messrs. King and Rowney, it will be observed, assume the
existence of calcite as a replacement pseudomorph after serpen-
tine, but give no evidence of the possibility of such pseudo-
morphs. Both Rose and Bischof regard serpentine itself as
in all cases, of pseudomorphous origin, and as the last result
of the changes of a number of mineral species, but give us no
example of the pseudomorphous alteration of serpentine
itself. It is, according to Bischof, the very insolubility and
unalterability of serpentine which cause it to appear as the
final result of the change of so many mineral species. Delesse,
moreover, in his carefully prepared table of pseudomorphous
minerals, in which he has resumed the results of his own and
all preceding observers, does not admit the pseudomorphic re-
placement of serpentine by calcite, nor indeed by any other
OPPONENTS AND OBJECTIONS.
201
species.* If, then, such pseudomorphs exist, it appears to be
a fact hitherto unobserved, and our authors should at least
have given us some evidence of this remarkable case of pseu-
domorphism by which they seek to support their singular
hypothesis.
" I hasten to say, however, that I reject with Scheerer,Delesse
and Naumann, a great part of the supposed cases of mineral
pseudomorphism, and do not even admit the pseudomorphous
origin of serpentine itself, but believe that this, with many
other related silicates, has been formed by direct chemical pre-
cipitation. This view, which our authors do me the honour to
criticise, was set forth by me in 1860 and 1861,t and will be
found noticed more in detail in the Geological Report of
Canada, for 1866, p. 229. I have there and elsewhere main-
tained that * steatite, serpentine, pyroxene, hornblende, and in
many cases garnet, epidote, and other silicated minerals, are
formed by a crystallization and molecular re-arrangement of
silicates, generated by chemical processes in waters at the
earth's surface.' J
" This view, which at once explains the origin of all these
bedded rocks, and the fact that their constituent mineral
species, like silica and carbonate of lime, replace the perishable
matter of organic forms, is designated by Messrs. King and
Rowney * as so completely destitute of the characters of a
scientific hypothesis as to be wholly unworthy of consideration,
and they speak of my attempt to maintain this hypothesis as
* a total collapse.' How far this statement is from the truth
my readers shall judge. My views as to the origin of serpen-
tine and other silicated minerals were set forth by me as above
in 1860-1864, before anything was known of the mineralogy of
Eozoon, and were forced upon me by my studies of the older
crystalline schists of North America. Naumann had already
pointed out the necessity of some such hypothesis when he
protested against the extravagances of the pseudomorphist
* Annales des Mines, 5, xvi., 317.
t Amer. Joum. Science (2), xxix., 284 ; xxxii., 28S.
J Ibid., xxxvii., 266 ; xxxviii., 183.
I
202
THE DAV/N OP LIFE.
school, and maintained that the beds of various silicates found
in the crystalline schists are original deposits, and not formed
by an epigenic process {Geognosie, ii., 65, 154, and Bull.
Soc. Geol. de France, 2, xviii., 678). This conclusion of
Naumann's I have attempted to explain and support by
numerous facts and observations, which have led me to the
hypothesis in question. Giimbel, who accepts Naumann's
view, sustains my hypothesis of the origin of these rocks in a
most emphatic manner,* and Credner, in discussing the genesis
of the Eozoic rocks, has most ably defended it.f So much
for my theoretical views so contemptuously denounced by
Messrs. King and Rowney, which are nevertheless unhesita-
tingly adopted by the two geologists of the time who have
made the most special studies of the rocks in question, —
Giimbel in Germany, and Credner in North America.
'* It would be a thankless task to follow Messrs. King and
Rowney through their long paper, which abounds in state-
ments as unsound as those I have just exposed, but I cannot
conclude without calling attention to one misconception of
theirs as to my view of the origin of limestones. They quote
Professor Hull's remark to the effect that the researches of
the Canadian geologists and others have shown that the oldest
known limestones of the world owe their origin to Eozoon, and
remark that the existence of great limestone beds in the Eozoic
rocks seems to have influenced Lyell, Ramsay, and others in
admitting the received view of Eozoon. Were there no other
conceivable source of limestones than Eozoon or similar cal-
careous skeletons, one might suppose that the presence of such
rocks in the Laurentian system could have thus influenced
these distinguished geologists, but there are found beneath the
Eozoon horizon two great formations of limestone in which
this fossil has never been detected. When found, indeed, it
owes its conservation in a readily recognisable form to the
* Proc. Royal Bavarian Acad, for 1866, translated in Can,
Naturalist, iii., 81.
t Die Gliederung der Eozoischen Formations gruppe Nord.-
AmerihaSy — a Thesis defended before the University of Leipzig,
March 15, 1869, by Dr. Hermann Credner. Halle, 1869, p. 63.
OPPONENTS AND OBJECTIONS.
203
fact, that it was preserved by the introduction of serpentine at
the time of its growth. Above the unbroken Eozoon reefs are
limestones made up apparently of the debris of Eozoon thus
preserved by serpentine, and there is no doubt that this cal-
careous rhizopod, growing in water where serpentine was not
in process of formation, might, and probably did, build up pure
limestone beds like those formed in later times from the ruins
of corals and crinoids. Nor is there anything inconsistent in
this with the assertion which Messrs. King and Rowney quote
from me, viz., that the popular notion that all limestone forma-
tions owe their origin to organic life is based upon a fallacy.
The idea that marine organisms originate the carbonate of
lime of their skeletons, in a manner somewhat similar to that
in which plants generate the organic matter of theirs, appears
to be commonly held among certain geologists. It cannot,
however, be too often repeated that animals only appropriate
the carbonate of lime which is furnished them by chemical
reaction. Were there no animals present to make use of it,
the carbonate of lime would accumulate in natural waters till
these became saturated, and would then be deposited in an in-
soluble form ; and although thousands of feet of limestone have
been formed from the calcareous skeletons of marine animals,
it is not less true that great beds of ancient marble, like many
modern travertines and tufas, have been deposited without
the intervention of life, and even in waters from which living
organisms were probably absent. To illustrate this with the
parallel case of silicious deposits, there are great beds made
up of silicious shields of diatoms. These during their lifetime
extracted from the waters the dissolved silica, which, but for
their intervention, might have accumulated till it was at length
deposited in the form of schist or of crystalline quartz. In either
case the function of the coral, the rhizopod, or the diatom is
limited to assimilating the carbonate of lime or the silica from
its solution, and the organised form thus given to these sub-
stances is purely accidental. It is characteristic of our
authors, that, rather than admit the limestone beds of the
Eozoon rocks to have been formed like beds of coralline lime-
stone, or deposited as chemical precipitates like travertine,
%\
2.04
THE DAWN OP LIFE.
thoy prefer, as they assure us, to regard them as the results of
that hitherto unheard-of process, the pseudomorphism of ser-
pentine ; as if the deposition of the carbonate of lime in the
place of dissolved serpentine were a simpler process than its
direct deposition in one or the other of the ways which all the
world understands ! "
C. Dii. Carpenter on the Foraminiferal Relations of
EozooN.
In the Annals of Natural History, for June, 1874, Dr. Car-
penter has given a crushing reply to some objections raised in
that journal by Mr. Carter. He first shows, contrary to the
statement of Mr. Carter, that the fine nummuline tubulation
corresponds precisely in its direction with reference to the
chambers, with that observed in Nuramulites and Orbitoides.
In the second place, he shows by clear descriptions and figures,
that the relation of the canal system to the fine tubulation is
precisely that which he had demonstrated in more recent num-
muline and rotaline Foraminifera. In the third place he ad-
duces additional facts to show that in some specimens of
Eozoon the calcareous skeleton has been filled with calcite
before the introduction of any foreign mineral matter. He
concludes the argument in the following words : —
" I have thus shown : — (1) that the * utter incompatibility '
asserted by my opponents to exist between the arrangement of
the supposed ' nummuline tubulation ' of Eozoon and true
Nummuline structure, so far from having any real existence,
really furnishes an additional point of conformity ; and (2)
that three most striking and complete points of conformity
exist between the structure of the best-preserved specimens of
Eozoon, and that of the Nummulites whose tubulation I de-
scribed in 1849, and of the Calcarina whose tubulation and
canal system I described in 1860.
" That I have not troubled myself to reply to the reiterated
arguments in favour of the doctrine [of mineral origin] ad-
vanced by Professors King and Rowney on the strength of the
occurrence of undoubted results of mineralization in the Cana-
OPPONENTS AND OBJECTIONS.
205
dian Ophite, and of still more marked evidences of the same
action in other Ophites, has been simply because these argu-
ments appeared to me, as I thought they must also appear to
others, entirely destitute of logical force. Every scientific
palaeontologist I have ever been acquainted with has taken the
best preserved specimens, not the ivoret, as the basis of his
reconstructions ; and if he should meet with distinct evidence
of characteristic organic structure in even a very small frag-
ment of a doubtful form, he would consider the organic origin
of that form to be thereby substantiated, whatever might be
the evidence of purely mineral arrangement which the greater
part of his specimen may present, — since he would regard
that arrangement as a probable result of sichseqment mineral-
ization, by which the original organic structure has been more
or less obscured. If this is not to be our rule of interpreta-
tion, a large part of the palaeontological work of our time must
be thrown aside as worthless. If, for example. Professors
King and Eowney were to begin their study of Nummulites by
the examination of their most mineralized forms, they would
deem themselves justified (according to their canons of inter-
pretation) in denying the existence of the tubulation and
canalization which I described (in 1849) in the N. laevigata pre-
served almost unaltered in the London Clay of Bracklesham
Bay.
" My own notions of Eozoic structure have been formed on the
examination of the Canadian specimens selected by the experi-
enced discrimination of Sir William Logan, as those in which
there was least appearance of metamorphism ; and having
found in these what I regarded as unmistakable evidence of an
organic structure conformable to the foramin iferal type, I
cannot regard it as any disproof of that conformity, either to
show that the true Eozoic structure has been frequently
altered by mineral metamorphism, or to adduce the occurrence
of Ophites more or less resembling the Eozoon of the Canadian
Laurentians at various subsequent geological epochs. The
existence of any number or variety of purely mineral Ophites
would not disprove the organic origin of the Canadian Eozoon
— unless it could be shown that some wonderful process of
liiiUii
i.
*i
1
206
THE DAWN OF LIFE.
mineralization is competent to construct not only its multi-
plied alternating lamellaB of calcite and serpentine, the den-
dritic extensions of the latter into the former, and the 'acicular
layer' of decalcified specimens, but (1) the pre-exieting canal-
ization of the calcareous lamellae, (2) the iinfilled nummuline
tuhidation of the proper wall of the chambers, and (3) the
peculiar calcarine relation of the canalization and tubulation,
here described and figured from specimens in the highest state
of preservation, showing the least evidence of any mineral
change.
" On the other hand. Professors King and Rowney began
their studies of Bozoic structure upon the Galway Ophite — a
rock which Sir Roderick Murchison described to me at the
time as having been so much * tumbled about,' that he was
not at all sure of its geological position, and which exhibits
such obvious evidences of mineralization, with such an entire
absence of any vestige of organic structure, that I should
never for a moment have thought of crediting it with an or-
ganic origin, but for the general resemblance of its serpentine-
grains to those of the ' acervuline ' portion of the Canadian
Eozoon. They pronounced with the most positive certainty
upon the mineral origin of the Canadian Eozoon, before they
had subjected transparent sections of it to any of that careful
comparison with similar sections of recent Foraminifera, which
had been the basis of Dr. Dawson's original determination, and
of my own subsequent confirmation, of its organic structure.
its multi-
, the den-
' acicular
ng canal-
tmmuUne
a (3) the
bulation,
Lest state
mineral
y began
ahite — a
e at the
he was
exhibits
1 entire
should
1 an or-
lentine-
<nadian
rtainty
e they
3areful
which
►n, and
cture.
H ;
Plate VIII.
X 60
i;:iil,..mi;!i.l;:;'N';i|il'li'''"
X 6
Eozoon and Chrysotile Veins, etc.
Fib. 1.— Portion of two laminae and intervening serpentine, with chrysotile
vein, (a.) Proper wall tubulated, (b.) Intermediate skeleton, with large
canals, (c.) Openings of small chamberlets filled with serpentine, (s.) Ser-
pentine filling chamber, (gi.) Vein of chrysotile, showing its difference from
the proper wall.
¥ia. 2.— Junction of a canal and the proper wall. Lettering as in Fig. 1.
Fig. 3.— Proper wall shifted by a fault, and more recent chrysotile vein not
flaulted. Lettering as in Fig. 1.
Fig. 4.— Large and small canals filled with dolomite.
Pig. 5.— Abnormally thick portion of intermediate skeleton, with large tubes
and small canals filled with dolomite.
CHAPTER VIII.
THE DAWN-ANIMAL AS A TEACHER IN SCIENCE.
The thoughts suggested to the philosophical natural-
ist by the contemplation of the dawn of life on our
planet are necessarily many and exciting, and the
subject Las in it the materials for enabling the
general reader better to judge of some of the theories
of the origin of life agitated in our time. In this
respect our dawn-animal has scarcely yet had justice ;
and we may not be able to render this in these pages.
Let us put it into the witness-box, however, and try to
elicit its testimony as to the beginnings of life.
Looking down from the elevation of our physio-
logical and mental superiority, it is difficult to realize
the exact conditions in which life exists in creatures so
simple as the Protozoa. There may perhaps be higher
intelligences that find it equally difficult to realize how
life and reason can manifest themselves in such poor
houses of clay as those we inhabit. But placing our-
selves near to these creatures, and entering as it were
into sympathy with them, we can understand something
of their powers and feelings. In the first place it is
plain that they can vigorously, if roughly, exercise
those mechanical, chemical, and vegetative powers of
208
THE DAWN OF LIFE.
life which are characteristic of the animal. They can
seize, swallow, digest, and assimilate food; and, employ-
ing its albuminous parts in nourishing their tissues,
can burn away the rest in processes akin to our respi-
ration, or reject it from their system. Like us, they
can subsist only on food which the plant has previously
produced; for in this world, from the beginning of
time, the plant has been the only organism which could
use the solar light and heat as forces to enable it to
turn the dead elements of matter into living, growing
tissues, and into organic compounds capable of nourish-
ing the animal. Like us, the Protozoa expend the food
which they have assimilated in the production of
animal force, and in doing so cause it to be oxidized,
or burnt away, and resolved again into dead matter.
It is true that we have much more complicated appa-
ratus for performing these functions, but it does not
follow that this gives us much real superiority, except
relatively to the more difficult conditions of our exist-
ence. The gourmand who enjoys his dinner may have
no more pleasure in the act than the Amoeba which
swallows a Diatom ; and for all that the man knows of
the subsequent processes to which the food is sub-
jected, his interior might be a mass of jelly, with
extemporised vacuoles, like that of his humble fellow-
animal. The workman or the athlete has bones and
muscles of vastly complicated structure, but to him the
muscular act is as simple and unconscious a process as
the sending out of a pseudopod to a Protozoon. The
clay is after all the same, and there may be as much
THE DAWN-ANIMAL AS A TEACHER IN SCIENCE. 209
credit to the artist in making a simple organism with
varied powers, as a more complex frame for doing nicer
work. It is a weakness of humanity to plume itself
on advantages not of its own making, and to treat its
superior gifts as if they were the result pf its own
endeavours. The truculent traveller who illustrated
his boast of superiority over the Indian by compar-
ing his rifle with the bow and arrows of the savage,
was well answered by the question, " Can you make a
rifle ? " and when he had to answer, " No,'' by the
rejoinder, " Then I am at least better than you, for I
can make my bow and arrows." The Amoeba or the
Eozoon is probably no more than we its own creator ;
but if it could produce itself out of vegetable matter
or OLi of inorganic substances, it might claim in so far
a higher place in the scale of being than we ; and as
it is, it can assert equal powers of digestion, assimila-
tion, and motion, with much less of bodily mechanism.
In order that we may feel, a complicated apparatus
of nerves and brain-cells has to be constructed and set
to work ; but the Protozoon, without any distinct brain,
is all brain, and its sensation is simply direct. Thus
vision in these creatures is probably performed in a
rough way by any part of their transparent bodies,
and taste and smell are no doubt in the same case.
'W'Tiether they have any perception of sound as distinct
from the mere vibrations ascertained by touch, we do
not know. Here also we are not far lemoved above the
Protozoa, especially those of us to whom touch, see-
ing, and hearing are mere feelings, without thought
210
THE DAWN OP LIFE.
or knowledge of the apparatus employed. We ruight
so far as well be Amcebas. As we rise higher we
meet with more differences. Yet it is evident that our
gelatinous fellow-being can feel pain, dread danger,
desire possessions, enjoy pleasure, and in a simple un-
conscious way entertain many of the appetites and
passions that affect ourselves. The wonder is that
with so little of organization it can do so much. Yet,
perhaps, life can manifest itself in a broader and more
intense way where there is little organization ; and a
highly strung and complex organism is not so much a
necessary condition of a higher life as a mere means of
better adapting it to its present surroundings. Those
philosophies which identify the thinking mind with the
material organism, must seem outrageous blunders to
an Amoeba on the one hand, or to an angel on the
other, could either be enabled to understand them;
which, however, is not very probable, as they are too
intimately bound up with the mere prejudices incident
to the present condition of our humanity. In any case
the Protozoa teach us how much of aaimal function
may be fulfilled by a very simple organism, and warn
us against the fallacy that creatures of this simple
structure are necessarily nearer to inorganic matter,
and more easily developed from it than beings of more
complex mould.
A similar lesson is tau^rht by the complexity of their
skeletons. We speak in a crude unscientific way of
these animals accumulating calcareous matter, and
building up reefs of limestone. We must, however,
THE DAWN-ANIMAL AS A TEi "■FEE IN SCIENCE. 211
bear in mind that tliey are as dependent on their food
for the materials of their skeletons as we are, and that
their crusts grow in the interior of the sarcode just as
our bones do within our bodies. The provision even
for nourishing the interior Oi the skeleton by tubuli
and canals is in principle similar to that involved in
the Haversian canals, cells, and canalicules of bone.
The Amoeba of course knows neither more nor less of
this than the average Englishman. It is altogether a
matter of unconscious growth. The process in the
Protozoa strikes s^ ne minds, however, as the more
wonderful of the two. It is, says an eminent
modern physiolog'st, a matter of "profound signifi-
cance " that this "particle of jelly [the sarcode of a
Foraminifer] is capable of guiding physical forces in
such a manner as to give rise to these exquisite and
almost mathematically arranged structures." Respect-
ing the structures themselves there is no exaggeration
in this. No arch or dome framed by human skill is
more perfect in beauty or in the realization of mechan-
ical ideas than the tests of some Foraminifera, and
none is so complete and wonderful in its internal
structure. The particle of jelly, however, is a figure of
speech. The body of the humblest Foraminifer is
much more than this. It is an organism with divers
parts, as we have already seen in cu previous chapter,
and it is endowed with the mysterious forces of life
which in it guide the physical forces, just as they do in
building up phosphate of lime in our bones, or indeed
just as the will of the architect does in building a
mi
' 1
, i
t
^la^MB
1
1
i
1
!
1
i
i
I
1
H
J
212
THE DAWN OF LIFE.
palace. The profound significance which this has,
reaches beyond the domain of the physical and vital,
even to the spiritual. It clings to all our conceptions
of living things : quite as much, for example, to the
evolution of an animal with all its parts from a one-
celled germ, or to the connection of brain-cells with
the manifestations of intelligence. Viewed in this
way, we may share with the author of the sentence I
have quoted his feeling of veneration in the presence
of this great wonder of animal life, " burning, and not
consumed," nay, building up, and that in many and
beautiful forms. We may realize it mtv/j of all in the
presence of the organism which was perhaps the first
to manifest on our planet these marvellous powers.
We must, however, here also, beware of that credulity
which makes too many thinkers limit their conceptions
altogether to physical force in matters of this kind.
The merely materialistic physiologist is really in no
better position than the savage who quails before the
thunderstorm, or rejoices in the solar warmth, and see-
ing no force or power beyond, fancies himself in the
immediate presence of his God. In Eozoon we must
discern not only a mass of jelly, but a being endowed
with that higher vital force which surpasses vegetable
life and also physical and chemical forces; and in this
animal energy we must see an emanation from a Will
higher than our own, ruling vitality itself ; and this not
merely to the end of constructing the skeleton of a
Protozoon, but of elaborating all the wonderful de-
velopments of life that were to follow in succeeding
THE DAWN-ANIMAL AS A TEACHER IN SCIENCE. 213
ages, and with reference to which the production and
growth of this creature were initial steps. It is
this mystery of design which really constitutes the
"profound significance" of the foraminiferal skele-
ton.
Another phenomenon of animality forced upon our
notice by the Protozoa is that of the conditions of life
in animals not individual, as we are, but aggre-
gative and cumulative in indefinite masses. What, for
instance, the relations to each other of the Polyps,
growing together in a coral mass, of the separate parts
of a Sponge, or the separate cells of a Foraminifer, or
of the sarcode mass of an indefinitely spread out
Stromatopora or Bathybius. In the case of the
Polyps, we may believe that there is special sensa-
tion in the tentacles and oral opening of each indi-
vidual, and that each may experience hunger when in
want, or satisfaction when it is filled with food, and
that injuries to one part of the mass may indirectly
affect other parts, but that the nutrition of the whole
mass may be as much unfelt by the individual Polyps
as the processes going on in our own bones are by us.
So in the case of a large Sponge or Foraminifer, there
may be some special sensation in individual cells,
pseudopods, or segments, and the general sensation
may be very limited, while unconscious living powers
pervade the whole. In this matter of aggregation of
animals we have thus various grades. The Foramini-
fers and Sponges present us with the simplest of all ,
and that which most resembles the aggregation of
214
THE DAWN OF LIFE.
buds in the plant. The Polyps and complex Bryozoons
present a higher and more specialised type; and though
the bilateral symmetry which obtains in the higher
animals is of a different nature, it still at least reminds
us of that multiplication of similar parts which we see
in the lower grades of being. It is worthy of notice
here that the lower animals which show aggregative
tendencies present but imperfect indications, or none
at all, of bilateral symmetry. Their bodies, like those
of plants, are for the most part built up around a
central axis, or they show tendencies to spiral modes
of growth.
It is this composite sort of life which is connected
with the main geological function of the Foraminifer.
While active sensation, appetite, and enjoyment per-
vade the pseudopods and external sarcode of the mass,
the hard skeleton common to the whole is growing
within; and in this way the calcareous matter is
gradually removed from the sea water, and built up
in solid reefs, or in piles of loose foraminiferal shells.
Thus it is the aggregative or common life, alike in
Foraminifers as in Corals, that tends most powerfully
to the accumulation of calcareous matter; and those
creatures whose life is of this complex character are
best suited to be world-builders, since the result of
their growth is not merely a cemetery of their osseous
remains, but a huge communistic edifice, to which
multitudes of lives have contributed, and in which
successive generations take up their abode on the
remains of their ancestors. This process, so potent iu
THE DAWN-ANIMAL AS A TEACHER IN SCIENCE.
215
3ryozoons
id though
le higher
t reminds
eh we see
of notice
gregative
, or none
like those
around a
:al modes
jonnected
raminifer.
aent per-
the mass,,
growing
aiatter is
built up
al shells.
alike in
owerfully
nd those
icter are
result of
L' osseous
which
in which
1 on the
3otent iu
the progress of the earth^s geological history, began,
as far as we know, with Eozoon.
Whether, then, in questioning our proto-foraminifer,
we have reference to the vital functions of its gelati-
nous sarcode, to the complexity and beauty of its
calcareous test, or to its capacity for effecting great
material results through the union of individuals, we
perceive that we have to do, not with a low condition
of those powers which we designate life, but with the
manifestation of those powers through the means of a
simple organism ; and this in a degree of perfection
which we, from our point of view, would have in the
first instance supposed impossible.
If we imagine a world altogether destitute of life, we
still might have geological formations in progress.
Not only would volcanoes belch forth their liquid lavas
and their stones and ashes, but the waves and currents
of the ocean and the rains and streams on the land,
with the ceaseless decomposing action of the carbonic
acid of the atmosphere, would be piling up mud, sand,
and pebbles in the sea. There might even be some
formation of limestone taking place where springs
charged with bicarbonate of lime were oozing out on
the land or the bottom of the waters. But in such a
world all the carbon would be in the state of carbonic
acid, and all the limestone would either be diffused in
small quantities through various rocks or in limited
local beds, or in solution, perhaps as chloride of cal-
cium, in the sea. Dr. Hunt has given chemical
grounds for supposing that the most ancient seas were
216
THE DAWN OP LIFE.
S !
I'
largely supplied with this very soluble salt, instead of
the chloride of sodium, or common salt, which now
prevails in the sea-water.
Where in such a world would life be introduced ?
on the land or in the waters ? All scientific proba-
bility would say in the latter. The ocean is now
vastly more populous than the land. The waters
alone aflford the conditions necessary at once for the
most minute and the grandest organisms, at once for
the simplest and for others of the most complex cha-
racter. Especially do they afford the best conditions
for those animals which subsist in complex communi-
ties, and which aggregate large quantities of mineral
matter in their skeletons. So true is this that up to
the present time all the species of Protozoa and of the
animals most nearly allied to them are aquatic. Even
in the waters, however, plant life, though possibly in
very simple forms, must precede the animal.
Let humble plants, then, be introduced :'n thn waters,
and they would at once begin to use the solar light for
the purpose of decomposing carbonic acid, and forming
carbon compounds which had not before existed, and
which independently of vegetable life would never have
existed. At the same time lime and other mineral
substances present in the sea-water would be fixed in
the tissues of these plants, either in a minute state
of division, as little grains or Coccoliths, or in more
solid masses like those of the Corallines and Nulli-
pores. In this way a beginning of limestone forma-
tion might be made, and quantities of carbonaceous
THE DAWN-ANIMAL AS A TEACHER IN SCIENCE. 217
and bituminous matter, resulting from the decay of
marine plants might accumulate in the sea-bottom.
Now arises the opportunity for animal life. The
plants have collected stores of organic matter, and
their minute germs, along with microscopic species, are
floating everywhere in the sea. Nay, there may be
abundant examples of those Amoeba-like germs of
aquatic plants, simulating for a time the life of the
animal, and then returning into the circle of vegetable
life. In these some might see precursors of the Pro-
tozoa, though they are probably rather prophetic ana-
logues than blood relations. The plant has fulfilled
its function as far as the waters are concerned, and
now arises the opportunity for the animal. In what
form shall it appear ? Many of its higher forms, those
which depend upon animal food or on the more com-
plex plants for subsistence, would obviously be un-
suitable. Further, the sea-water is still too much
saturated with saline matter to be fit for the higher
animals of the waters. Still further,, there may be a
residue of internal heat forbidding coolness, and that
solution of free oxygen which is an essential condition
of existence to most of the modern animals. Some-
thing must be found suitable for this saline, imper-
fectly oxygenated, tepid sea. Something too is wanted
that can aid in introducing conditions more favourable
to higher life in the future. Our experience of the
modern world shows us that all these conditions can be
better fulfilled by the Protozoa than by any other
creatures. They can live now equally in those great
it
218
THE DAWN OP LIFE.
depths of ocean where the conditions are most unfa-
vourable to other forms of life, and in tepid unhealthy
pools overstocked with vegetable matter in a state of
putridity. They form a most suitable basis for higher
forms of life. They have remarkable powers of remov-
ing mineral matters from the waters and of fixing
them in solid forms. So in the fitness of things
Eozoon is just what we need, and after it has spread
itself over the mud and rock of the primeval seas, and
built up extensive reefs therein, other animals may be
introduced capable of feeding on it, or of sheltering
themselves in its stony masses, and thus we have the
appropriate dawn of animal life.
But what are we to say of the cause of this new
series of facts, so wonderfully superimposed upon the
merely vegetable and mineral ? Must it remain to us
as an act of creation, or was it derived from some pre-
existing matter in which it had been potentially
present ? Science fails to inform us, but conjectural
'^ phylogeny " steps in and takes its place. Haeckel,
the prophet of this new philosophy, waves his magic
wand, and simple masses of sarcode spring from inor-
ganic matter, and form diffused sheets of sea-slime,
from which are in time separated distinct Amoeboid
and Foraminiferal forms. Experience, however, gives
us no facts whereon to build this supposition, and it
remains neither more nor less scientific or certain than
that old fancy of the Egyptians, which derived ani-
mals from the fertile mud of the Nile.
If we fail to learn anything of the origin of Eozoon,
THE DAWN-ANIMAL AS A TEACHER IN SCIENCE. 219
and if its life-processes are just as inscrutable as those
of higher creatures, we can at least inquire as to its
history in geological time. In this respect we find in
the first place that the Protozoa have not had a monopoly
in their profession of accumulators of calcareous rock.
Originated by Eozoon in the old Laurentian time,
this process has been proceeding throughout the geo-
logical ages ; and while Protozoa, equally simple with
the great prototype of the race, have been and are
continuing its function, and producing '^.ew limestones
in every geological period, and so adding to the
volume of the successive formations, new workers of
higher grades have been introduced, capable of enjoy-
ing higher forms of animal activity, and equally of
labouring at the great task of continent-building ; of
existing, too, in seas less ricn in mineral substances
than those of the Eozoic time, and for that very reason
better suited to higher and more skilled artists. It is
to be observed in connection with this, that as the work
of the Foraminifers has thus been assumed by others,
their size and importance have diminished, and the
grander forms of more recent times have some of them
been fain to build up their hard parts of cemented sand
instead of limestone.
But we further find that, while the first though
not the only organic gatherers of limestone from the
ocean waters, they have had to do, not merely with
the formation of calcareous sediments, but also with
that of silicious deposits. The greenish silicate called
glauconite, or greensand, is found to be associated
220
THE DAWN OP LIFE.
with much of the foraminiferal slime now accumu-
lating in the ocean, and also with the older deposits
of this kind now consolidated in chalks and similar
rocks. This name glauconite is, as Dr. Hunt has
shown, employed to designate not only the hydrous
silicate of iron and potash, which perhaps has the
best right to it, but also compounds which contain in
addition large percentages of alumina, or magnesia,
or both ; and one glauconite from the Tertiary lime-
stones near Paris, is said to be a true serpentine, or
hydrous silicate of magnesia.* Now the association
of such substances with Foraminifera is not purely
accidental. Just as a fragment of decaying wood,
imbedded in sediment, has the power of decomposing
soluble silicates carried to it by water, and parting
with its carbon in the form of carbonic acid, in ex-
change for the silioa, and thus replacing, particle by
particle, the caa'bon of the wood with silicon, so
that at length it becomes petrified into a flinty mass,
so the sarcode of a Foraminifer, which is a more dense
kind of animal matter than is usually supposed, can
in like manner abstract silica from the surrounding
water or water-soaked sediment. From some pecu-
liarity in the conditions of the case, however, our
Protozoon usually becomes petrified with a hydrous
silicate instead of with pure silica. The favourable
conditions presented by th^ deep sea for the combina-
tion of silica with bases, may perhaps account in part
* Berthier, quoted by Hunt.
Uk.
\
fF-r^^
n
THE DAWN-ANIMAL AS A TEACHER IN SCIENCE. 221
i il
accumn-
deposits
d similar
[unt has
hydrous
has the
)ntaiii in
lagnesia,
TV Hme-
ntine, or
sociation
t purely
J wood,
mposing
parting
in ex-
tiele by
eon, so
Y mass,
e dense
ed, can
unding
3 pecu-
er, our
lydrous
curable
mbina-
in part
,
for this. But whatever the cause, it is usual to find
fossil Foraminifera with their sarcode replaced by
such material. We also find beds of glauconite re-
taining the forms of Foraminifera, while the Kjalcareous
tests of these have been removed, apparently by acid
waters.
One consideration which, though conjectural, de-
serves notice, is connected with the food of these
humble animals. They are known to feed to a large
extent on minute plants, the Diatoms, and other
organisms having silica in their skeletons or cell-
walls, and consequently soluble silicates in their juices.
The silicious matter contained in these organisms is
not wanted by the Foraminifera for their own
skeletons, and will therefore be voided by them as
an excrementitious matter. In this way, where
Foraminifera greatly abound, there may be a large
production of soluble silica and silicates, in a condition
ready to enter into new and insoluble ccmpounds, and
to fill the cavities and pores of dead shells. Thus
glauconite and even serpentine may, in a certain
sense, be a sort of foraminiferal coprolitic matter or
excrement. Of course it is not necessary to suppose
that this is the only source of such materials. They
may be formed in other ways ; but I suggest this as at
least a possible link of connection.
Whether or not the conjecture last mentioned has
any validity, there is another and most curious bond
of connectior between oceanic Protozoa and silicious
deposits. Professor Wyville Thompson reports from
222
THE DAWN OF LIFE.
the Challenger soundings, that in certain areas
of the South Pacific the ordinary foraminiferal ooze
is replaced by a peculiar red clay, which he attributes
to the action of water laden with carbonic acid, in
removing all the lime, and leaving this red mud as a
sort of ash, composed of silica, alumina, and iron oxide.
Now this is in all probability a product of the decora-
position and oxidation of the glauconitic matter
contained in the ooze. Thus we learn that when areas
on which calcareous deposits havt- been accumulated
by Protozoa, are invaded by cold arctic or antarctic
waters charged with carbonic acid, the carbonate of
lime may be removed, and the glauconite left, or
even the latter may be decomposed, leaving silicious,
aluminous, and other deposits, which may be quite
destitute of any organic structures, or retain only
such remnants of them as have been accidentally or
by their more resisting character protected from de-
struction.* In this way it may be possible that many
silicious rocks of the Laurentian and Primordial ages,
which now show no trace of organization, may be
l-sr Eg
* The " red chalk " of Antrim, and that of Speeton, contain
arenaceous Foraminifera and silicious casts of their shells,
apparently different from typical glauconite, and the extremely
fine ferruginous and argillaceous sediment of these chalks may
well be decomposed glauconitic matter like that of the South
Pacific. I have found these beds, the hard limestones of the
French Neocomian, and the altered greensands of the Alps,
very instructive for comparison with the Laurentian lime-
stones ; and they well deserve study by all interested in such
subjects. •
THE DAWN-ANIMAL AS A TEACHER IN SCIENCE.
223
indirectly products of tlio action of life. When
the recent deposits discovered by the Chalhmger
dredgiugs shall have been more fully examined, we
may perhaps have the means of distinguishing such
rocks, and thus of still further enlarging our concep-
tions of the part played by Protozoa in the drama
of the earth's history. In any case it seems plain
that beds of greensand and similar hydrous silicates
may be the residue of thick deposits of foramini-
feral limestone or chalky matter, and that these
silicates may in their turn be oxidised and decomposed,
leaving beds of apparently inorganic clay. Such
beds may finally be consolidated and rendered crys-
talline by metamorphism, and thus a great variety
of silicated rocks may result, retaining little or no
indication of any connection with the agency of life.
We can scarcely yet conjecture the amount of light
which these new facts may eventually throw on the
serpentine and other rocks of the Eozoic age. In the
meantime they open up a noble field to chemists and
microscopists.
When the marvellous results of recent deep-sea
dredgings were first made known, and it was found
that chalky foraminiferal earth is yet accumulating in
the Atlantic, with sponges and sea urchins resembling
in many respects those whose remains exist in the
chalk, the fact was expressed by the statement that we
still live in the chalk period. Thus stated the con-
clusion is scarcely correct. We do not live in the
chalk period, but the conditions of the chalk period
224
THE DAWN OF LIFE.
w
still exist in the deep sea. We may say more than
this. To some extent the conditions of the Lauren-
tian period still exist in the sea, except in so far as they
have been removed by the action of the Foraminifera
and other limestone builders. To those who can
realize the enormous lapse of time involved in the geo-
logical history of the earth, this conveys an impression
almost of eternity in the existence of this oldest of all
the families of the animal kingdom.
We are still more deeply impressed with this when
we bring into view the great physical changes which
have occurred since the dawn of life. When we con-
sider that the skeletons of Eozoon contribute to form
the oldest hills of our continents ; that they have been
sealed up in solid marble, and that they are associated
with hard crystalline rocks contorted in the most fan-
tastic manner ; that these rocks have almost from the
beginning of geological time been undergoing waste to
supply the material of new formations ; that they have
witnessed innumerable subsidences and elevations of
the continents ; and that the greatest mountain chains
of the earth have been built up from the sea since
Eozoon began to exist, — we acquire a most profound
impression of the persistence of the lower forms of ani-
mal life, and know that mountains may be removed
and continents swept away and replaced, before the
least of the humble gelatinous Protozoa can finally
perish. Life maybe a fleeting thing in the individual,
but as handed down through successive generations
of beings, and as a constant animating power in
THE DAWN-ANIMAL AS A TEACHER IN SCIENCE. 225
successive organisms, it appears, like its Creator,
eternal.
This leads to another and very serious question.
How long did lineal descendants of Eozoon exist, and
do they still exist ? We may for the present consider
this question apart from ideas of derivation and ele-
vation into higher planes of existence. Eozoon as a
species and even as a genus may cease to exist with
the Eozoic age, and we have no evidence whatever
that Archaeocyathus, Stromatopora, or Receptaculites
are its modified descendants. As far as their struc-
tures inform us, they may as much claim to be original
creations as Eozoon itself. Still descendants of Eozoon
may have continued to exist, though we have not yet
met with them. I should not be surprised to hear of
a veritable specimen being some day dredged alive in
the Atlantic or the Pacific. It is also to be observed
that in animals so simple as Eozoon many varieties
may appear, widely difi'erent from the original. In
these the general form and habit of life are the most
likely things to change, the minute structures much
less so. "We need not, therefore, be surprised to find
its descendants diminishing in size or altering in
general form, while the characters of the fine tubula-
tion and of the canal system would remain. We need
not wonder if any sessile Foraminifer of the Nummu-
line group should prove to be a descendant of Eozoon.
It would be less likely that a Sponge or a Foraminifer
of the Rctaline typo should originate from it. If one
could only secure a succession of deep-sea limestones
Q
226
THE DAWN OF LIFE.
with Foraminifers, extending all tlie way from tlie
Laurentian to the present time, I can imagine nothing
more interesting than to compare the whole series,
with the view of ascertaining the limits of descent with
variation, and the points where new forms are intro-
duced. We have not yet such a series, but it may be
obtained ; and as Foraminifera are eminently cosmopo-
litan, occurring over vastly wide areas of sea-bottom,
and are very variable, they would afford a better test
of theories of derivation than any that can be obtained
from the more locally distributed and less variable ani-
mals of higher grade. I was much struck with this
recently, in examining a series of Foraminifera from
the Cretaceous of Manitoba, and comparing them with
the varietal forms of the same species in the interior of
Nebraska, 600 miles to the south, and with those of
the English chalk and of the modern seas. In all
these different times and places we had the same spe-
cies. In all they existed under so many varietal forms
passing into each other, that in former times every
species had been multiplied into several. Yet in all,
the identical varietal forms were repeated with the
most minute markings alike. Here were at once
constancy the most remarkable and variations the
most extensive. If we dwell on the one to the exclu-
sion of the other, we reach only one-sided conclusions,
imperfect and unsatisfactory. By taking both in con-
nection wo can alone realize the full significance of the
facts. We cannot yet obtain such series for all geolo-
gical time ; but it may even now be worth while to
TtlE DAWN-ANIMAL AS A TEACHER IN SCIENCE. 227
T from tlie
ne nothing
aole series,
.escent witli
s are intro-
,t it may be
ly cosmopo-
sea-bottom,
1 better test
be obtained
variable ani-
jk witb this
linifera from
g them with
le interior of
rith those of
seas. In all
le same spe-
irietal forms
times every
Yet in all,
;ed with the
ere at once
iriations the
to the exclu-
conclusions,
both in con-
ficance of the
for all geolo-
Drth while to
iuquire, What do we know as to any modification in
the case of the primeval Foraminifers, whether with
reference to the derivation from them of other Pro-
tozoa or of higher forms of life ?
There is no link whatever in geological fact to con-
nect Eozoon with any of the Moll asks, Eadiates, or
Crustaceans of the succeeding Primordial. What may
be discovered in the future we cannot conjecture ; but
at present these stand before us as distinct creations.
It would of course be more probable that Eozoon
should be the ancestor of some of the Foraminifera of
the Primordial age, but strangely enough it is very
dissimilar from all these except Stromatopora; and
here, as already stated, the evidence of minute struc-
ture fails to a great extent, and Eozoon Bavaricum of
the Huronian age scarcely helps to bridge over the gap
which yawns in our imperfect geological record. Of
actual facts, therefore, we have none ; and those evolu-
tionists who have regarded the dawn-animal as an
evidence in their favour, have been obliged to have
recourse to supposition and assumption.
Taking the ground of the derivationist, it is con-
venient to assume (1) that Eozoon was either the first
or nearly the first of animals, and that, beiug a Pro-
tozoan of simple structure, it constitutes an appropriate
beginning of life ; (2) that it originated from some
unexplained change in the protoplasmic or albuminous
matter of some humble plant, or directly from inor-
ganic matter, or at least was descended from some
creature only a little more simple which had being in
i
228
THE DAWN OF LIFE.
this way j (3) that it had in itself unlimited capacities
for variation and also for extension in time ; (4) that it
tended to multiply rapidly, and at last so to occupy the
ocean that a struggle for existence arose; (5) that
though at first, from the very nature of its origin,
adapted to the conditions of the world, yet as these
conditions became altered by physical changes, it
was induced to accommodate itself to them, and so
to pass into new species and genera, until at last
it appeared in entirely new types in the Primordial
fauna.
These assumptions are, with the exception of the
first two, merely the . application to Eozoon of what
have been called the Darwinian laws of multiplication,
of limited population, of variation, of change of
physical conditions, and of equilibrium of nature. If
otherwise proved, and shown to be applicable to crea-
tures like Eozoon, of course we must apply them to it ;
but in so far as that creature itself is concerned they
are incapable of proof, and some of them contrary to
such evidence as we have. We have, for example, no
connecting link between Eozoon and any form of vege-
table life. Its structures are such as to enable us at once
to assign it to the animal kingdom, and if we seek for
connecting links between the lower animals and plants
we have to look for them in the modern waters. We
have no reason to conclude that Eozoon could multiply
so rapidly as to fill all the stations suitable for it, and
to commence a struggle for existence. On the con-
trary, after the lapse of untold ages the conditions for
; ■"■' •*"\'.r^-'-",'"
THE DAWN-ANIMAL AS A TEACHER IN SCIENCE. 229
the life of ForamiDifers still exist over two-thirds of
the surface of the earth. In regard to variation, we
have, it is true, evidence of the wide range of varieties
of species in Protozoa, within the limits of the group,
but none whatever of any tendency to pass into other
groups. Nor can it be proved that the conditions of
the ocean were so different in Cambrian or Silurian
times as to preclude the continued and comfortable
existence of Eozoon. New creatures came in which
superseded it, and new conditions more favourable in
proportion to these new creatures, but neither the new
creatures nor the new conditions were necessarily or
probably connected with Eozoon, any farther than that
it may have served newer tribes of animals for food,
and may have rid the sea of some of its superfluous
lime in their interest. In short, the hypothesis of evo-
lution will explain the derivation of other animals from
Eozoon if we adopt its assumptions, just as it will in
that case explain anything else, but the assumptions
are improbable, and contrary to such facts as we know.
Eozoon itself, however, bears some negative though
damaging testimony against evolution, and its argu-
ment may be thus stated in what we may imagine to
be its own expressions : — " I, Eozoon Canadense, being
a creature of low organization and intelligence, and of
practical turn, am no theorist, but have a lively ap-
preciation of such facts as I am able to perceive. I
found myself growing upon the sea-bottom, and know
not whence I came. I grew and flourished for ages,
and found no let or hindrance to my expansion, and
^^i'.:'
^j
230
THE DAWN OF LIFE.
abundance of food was always floated to me without
my having to go in search of it. At length a change
came. Certain creatures with hard snouts and jaws
began to prey on me. Whence they came I know not ;
I cannot think that they came from the germs which I
had dispersed so abundantly throughout the ocean.
Unfortunately, just at the same time lime became a
little less abundant in the waters, perhaps because of
the great demands I myself had made, and thus it was
not so easy as before to produce a thick supplemental
skeleton for defence. So I had to give way. I have
done my best to avoid extinction; but it is clear that I
must at length be overcome, and must either disappear
or subside into a humbler condition, and that other
creatures better provided for the new conditions of the
world must take my place.'' In such terms we may
suppose that this patriarch of the seas might tell his
history, and mourn his destiny, though he might
also congratulate himself on having in an honest
way done his duty and fulfilled his function in the
world, leaving it to other and perhaps wiser crea-
tures to dispute as to his origin and fate, while much
less perfectly fulfilling the ends of their own exist-
ence.
Thus our dawn-animal has positively no story to
tell as to his own introduction or his transmutation
into other forms of existence. He leaves the mystery
of creation where it was ; but in connection with the
subsequent history of life we can learn from him a
little as to the laws which have governed the succes-
THE DAWN-ANIMAL AS A TEACHER IN SCIENCE. 231
sion of animals in geological time. First, we may learn
that the plan of creation has been progressive, that there
has been an advance from the few, low, and generalized
types of the primaeval ocean to the more numerous,
higher, and more specialized types of more recent
times. Secondly, we learn that the lower types, when
first introduced, and before they were subordinated to
higher forms of life, existed in some of their grandest
modifications as to form and complexity, and that in
succeeding ages, when higher types were replacing
them, they were subjected to decay and degeneracy.
Thirdly, we learn that while the species has a limited
term of existence in geological time, any grand type of
animal existence, like that of the Foraminifera or
Sponges, for example, once introduced, continues and
finds throughout all the vicissitudes of the earth some
appropriate residence. Fourthly, as to the mode of
introduction of new types, or whether such creatures
as Eozoon had any direct connection with the subse-
quent introduction of mollusks, worms, or crustaceans,
it is altogether silent, nor can it predict anything as to
the order or manner of their introduction.
Had we been permitted to visit the Laurentian seas,
and to study Eozoon and its contemporary Protozoa
when alive, it is plain that we could not have foreseen
or predicted from the consideration of such organisms
the future development of life. No amount of study
of the prototypal Foraminifer could have led us dis-
tinctly to the conception of even a Sponge or a Polyp,
much less of any of the higher animals. Why is this ?
^''1
mmmm^m
232
THE DAWN OP LIFE.
The answer is that the improvement into such higher
types does not take place by any change of the ele-
mentary sarcode, either in those chemical, mechanical,
or vital properties which we can study, but in the add-
ing to it of new structures. In the Sponge, which is
perhaps the nearest type of all, we have the movable
pulsating cilium and true animal cellular tissue, and
along with this the spicular or fibrous skeleton, these
structures leading to an entire change in the mode of
life and subsistence. In the higher types of animals
it is the same. Even in the highest we have white
blood-corpuscles and germinal matter, which, in so far
as we know, carry on no higher forms of life than
those of an Amoeba ; but they are now made subordi-
nate to other kinds of tissue, of great variety and
complexity, which never have been observed to arise
out of the growth of any Protozoon. There would be
only a very few conceivable inferences which the high-
est finite intelligence could deduce as to the develop-
ment of future and higher animals. He might infer
that the foraminiferal sarcode, once introduced, might
be the substratum or foundation of other but unknown
tissues in the higher animals, and that the Protozoan
type might continue to subsist side by side with higher
forms of living things as they were successively intro-
duced. He might also infer that the elevation of the
animal kingdom would take place with reference to
those new properties of sensation and voluntary motion
in which the humblest animals diverge from the life of
the plant.
THE DAWN-ANIMAL AS A TEACHER IN SCIENCE. 233
It is important that these points should be clearly
before our minds, because there has been current of
late among naturalists a loose way of writing with
reference to them, which seems to have imposed on
many who are not naturalists. It has been said, for
example, that such an organism as Eozoon may include
potentially all the structures and functions of the
higher animals, and that it is possible that we might
be able to infer or calculate all these with as much
certainty as we can calculate an eclipse or any other
physical phenomenon. Now, there is not only no foun-
dation in fact for these assertions, but it is from our
present standpoint not conceivable that they can ever
be realized. The laws of inorganic matter give no
data whence any a ^priori deductions or calculations
could be made as to the structure and vital forces of
the plant. The plant gives no data from which we can
calculate the functions of the animal. The Protozoon
gives no data from which we can calculate the special-
ties of the Mollusc, the Articulate, or the Vertebrate.
Nor unhappily do the present conditions of life of
themselves give us any sure grounds for predicting the
new creations that may be in store for our old planet.
Those who think to build a philosophy and even a
religion on such data are mere dreamers, and have no
scientific basis for their dogmas. They are more
blind guides than our primaeval Protozoon himsel
would be, in matters whose real solution lies in the
harmony of our own higher and immaterial nature
with the Being who is the author of all life — the
234
THE DAWN OP LIFE.
•i^
Father " from whom every family in heaven and
earth is named/'
While this work was going through the press, Lyell,
the greatest geological thinker of our time, passed
away. In the preceding pages I have refrained from
quoting the many able geologists and biologists who
have publicly accepted the evidence of the animal
nature of Eozoon as sufficient, preferring to rest my
case on its own merits rather than on authority ; but
it is due to the great man whose loss we now mourn,
to say that, before the discovery of Eozoon, he had
expressed on general grounds his anticipation that
fossils would be found in the rocks older than the so-
called Primordial Series, and that he at once admitted
the organic nature of Eozoon, and introduced it, as a
fossil, into the edition of his Elements of Geology pub-
lished in the same year in which it was described.
!■■ • ■■«:
'^, m
and
APPENDIX.
CHARACTERS OF LAURENTIAN AND
HURONIAN PROTOZOA.
It may be useful to students to state the technical characters
of Eozoon, in addition to the more popular and general
descriptions in the preceding pages.
Genus EOZOON.
Foraminiferal skeletons, with irregular and often confluent
cells, arranged in concentric and horizontal laminyo, or some-
times piled in an acervuline manner. Septal orifices irregularly
disposed. Proper wall finely tubulated. Intermediate skeleton
with branching canals.
EozooN Canadense, Daioson.
In rounded masses or thick encrusting sheets, frequently of
large dimensions. Typical structure stroraatoporoid, or with
concentric calcareous walls, frequently uniting with each other,
and separating flat chambers, more or less mamraillated, and
spreading into horizontal lobes and small chamberlets ;
chambers often confluent and crossed by irregular calcareous
pillars connecting the opposite walls. Upper part often com-
posed of acervuline chambers of rounded forms. Proper wall
tubulated very finely. Intermediate skeleton largely de-
veloped, especially at the lower part, and traversed by lai'ge
canals, often with smaller canals in their interstices. Lower
laminas and chambers often three millimetres in thickness.
Upper laminaD and chambers one millimetre or less. Age
Laurentian and perhaps Hnronian.
236
THE DAWN OF LIFE.
i
Var, MINOR. — Supplemental skeleton wanting, except near
the base, and with very fine canals. Laminjo of sarcode much
mammillated, thin, and separated by very thin walls. Probably
a depauperated variety.
Var. ACERVULINA.— In oval or rounded masses, wholly acer-
vuline. Colls rounded ; intermediate skeleton absent or much
reduced ; cell-walls tubulated. This may be a distinct species,
but it closely resembles the acervuline parts of the ordinary
form.
EozooN Bavaricum, Giimhel.
Composed of small acervuline chambers, separated by con-
torted walls, and associated with broad plate-like chambers
below. Large canals in the thicker parts of the intermediate
skeleton. Differs from E. Canadense in its smaller and more
contorted chambers. Age probably Huronian.
Genus ARCH^OSPHERINA.
A provisional genus, to include rounded solitary chambers,
or globigerine assemblages of such chambers, with the cell-wall
surrounding them tubulated as in Eozoon. They may be
distinct organisms, or gemmge or detached fragments of
Eozoon. Some of them much resemble the bodies figured by
Dr. Carpenter, as geramas or ova and primitive chambers of
Orbitolites. They are very abundant on some of the strata
surfaces of the limestone at Cote St. Pierre. Age Lower
Laurentian.
APPENDIX.
236«
SYSTEMATIC POSITION OF EOZOON.
The unsettled condition of the classification of the Protozoa,
and our absolute ignorance of the animal matter of Eozoon,
render it difficult to make any statement on this subject more
definite than the somewhat vague intimations given in the
text. My own views at present, based on the study of recent
and fossil forms, and of tbe writings of Carpenter, Max
Schultzc, Carter, Wallich, Haeckel, and Clarcpode, may be
stated, though with some diffidence, as follows : —
I. The class Ehizopoda includes all the sarcodous animals
whose only external organs are pseudopodia, and is the lowest
class in the animal kingdom. Immediately above it are the
classes of the Sponges and of the flagellate and ciliate
Infusoria, which rise from it like two diverging branches.
II. The group of Ehizopods, as thus defined, includes
three leading orders, which, in descending grade, are as
follows : —
(a) Lohosa, or Amoeboid Ehizopods, including thoso with
distinct nucleus and pulsating vesicle, and thick
lobulate pseudopodia — naked, or in membranous
coverings.
(b) Badiolaria, or Polycistius and their allies, including those
with thread-like pseudopodia, with or without
a nucleus, and with the skeleton, when present,
silicious.
(c) Boticularia, or Foraminifera and their allies, including
those with thread-like and reticulating pseudo-
podia, with granular matter instead of a nucleus,
and with calcareous, membranous, or arenaceous
skeletons. '
The place of Eozoon will be in the lowest order, Beticularia.
III. The order Retlcularia may be farther divided into two
suh-orders, as follows : —
2366
THE DAWN OF LIFE.
(a) Perforata — having calcareous skeletons penetrated with
pores.
(6) Imperforata — having calcareous, membranous, or arena-
ceous skeletons, without pores.
The place of Eozoon will be in the higher sub-order.
Perforata.
IV. The sub-order Perforata includes three families — the
Nummulinidoe, GlohigorinidcB, and Lagemd(£. Of these Car-
penter regards the Nummulinidae as the highest in rank.
The place of Eozoon will be in the family Nummtdinidce, or
between this and the next family. This oldest known Proto-
zoon would thus belong to the highest family in the highest
sub-order of the lowest class of animals.
AI'PKNDIX.
2S0r
ated with
or arena-
ub-order,
Hies — the
lese Car-
ink.
inidce, or
n Proto-
5 highest
THE L.VTE SIR WILLIAM: E. LOGAN.
When writing i.!:3 dedication of this work, I little thought
that the eminent geologist and valued friend to whom it gave
me so much pleasure to tender this tribute of respect, would
have passed away before its publication. But so it is, and wo
have now to mourn, not only .iyell, who so frankly accepted the
evidence in favour of Eozoon. but Logan, who so boldly from
the first maintained its true nature as a fossil. This boldness
on his part is the more remarkable and impressive, from the
extreme caution by which ho was characterized, and which
induced him to take the most scrupulous pains to verify every
new fact before committing himself to it. Though Sir
William's early work in i ae Welsh coal-fields, his organization
and management of the Survey of Canada, and his reducing to
order for the first time ill the widely extended Pala3ozoic
formations of that great country, must always constitute
leading elements in his reputation, I think that in nothing
does he deserve greater crediD than in the skill and genius
with which he attacked the difficult problem of the Laurentian
rocks, unravelled their intricacies, and ascertained their true
nature as sediments, and the leading fii(!ts of their arrange-
ment and distribution. The discovery of Eozoon was one of
the results of this great work; and it was the firm conviction
to which Sir AViliiam had attained of the sediniencary cha-
racter of the rocks, which rendered his mind open to the
evidence of these contained fossils, and induced him even to
expect the discovery of them.
This would not be the proper place to dwell on the general
character and work of Sir William Logan, but I cannot close
Avithout referring to his untiring industry, his enthusiasm in
the investigatioii of nature, his cheerful and single-hearted
disposition, his earnest public spirit and patriotism — (pialities
which won for him the regard even of those who could little
appreciate the details of iiis work, and which did much to
enable him to attain to the success which he achieved.
«i,;|'! I
Sml^^M
i
■■*
r
INDEX.
Acervuline explained, 6G.
Acervuline Variety of Eozoon, 135.
Aggregative Growth of Animals,
213.
Aker Limestone, 197.
Amity Limestone, 197.
Amoeba described, 59.
Annelid Burrows, 133, 139.
ArchaDOspherinae, 137, 148,
Archffiocyathus, 151.
Arisaig, Supposed Eozoon of, 140.
Bathybius, 65.
Bavaria, Eozoon of, 148.
Beginning of Life, 215.
Billings, Mr.,— referred to, 41 ; on
Arcliffiocyathus, 151 ; on Ee-
ceptaculites, 1G3.
Calumet, Eozoon of, 38.
Calcarina, 74.
Calcite filling Tubes of Eozoon, 98.
Canal System of Eozoon, 40, 06,
107, 176, 181.
Carpenter — referred to, 41; on
Eozoon, 82 ; Reply to Carter, 204.
Caunopora, 158.
Chrysotile Veins, 107, 180.
Chemistry of Eozoon, 190.
Coccoliths, 70.
Coenostroma, 158.
Contemporaries of Eozoon, 127.
C6te St. Pierre, 20.
Dcrivution applied to Eozoon, 225.
Discovery of Eozoon, 35.
Eozoic Time, 7.
Eozoon, — Discovery of, 35 ; Struc-
ture of, 65 ; Growth of, 70 ; Frag-
mfints of, 74 ; Description of, 65,
77 (also Appendix); Note on by
Di-. Carpenter, 82 ; Thickened
"Walls of, 66 ; Preservation of,
100; Pores filled with Calcite,
97, 109; with Pyroxene, 108;
with Serpentine, 101 ; with Dolo-
mite, 109; in Limestone, 110;
Defective Specimens of, 113 ;
how Mineralized, 102, 116 ; its
Contemporaries, 127 ; Acervuline
Variety of, 135 ; Variety Minor
of, 135 ; Acadiauum, 140; Lava-
ricum, 148 ; Localities of, 166 ;
Harmony of with other Fossils,
171 ; Summary videuce
relating to, 176.
Faulted Eozoon, 182.
Foraminifcra, Notice of, 61.
238 INDEX.
I I
Fossils, how Mineralized, 93.
Fusulina, 74.
Glauconite, 100, 125, 220.
Graphite of Laurentian, 18, 27.
Greensand, 99.
Grenville, Eozoon of, 38.
Gtimhel on Laurentian Fossils, 124 ;
on Eozoon Bavaricum, 141.
Hastings, Rocks of, 57.
History of Discovery of Eozoon,
86.
Honeyman, Dr., referred to, 140.
Hunt, Dr. Sterry, referred to, 35 ;
on Mineralization of Eozoon,
115 ; on Silurian Fossils in-
filtrated with Silicates, 121 ; on
Minerals of the Laurentian, 123 ;
on Laurentian Life, 27 ; his He-
ply to Objections, 199.
Huronian Rocks, 9.
Intermediate Skeleton, 64.
Iron Ores of Laurentian, 19.
Jones, Prof. T. Rupert, on Eozoon,
42.
Iving, Prof., his Objections, 184.
Labrador Felspar, 13.
Laurentian Rocks, 7 ; Fossils of,
130; Graphite of, 18, 27; Iron
Ores of, 19 ; Limestones of, 17.
Limestones, Laurentian, 17 ;
Silurian, 98.
Localities of Eozoon, 166.
Loftusia, 164.
Lngan, Sir Wm., referred to, 36 ;
on Laurentian, 24 ; on Nature
of Eozoon, 37; Geological Re-
lations of Eozoon, 48; on Ad-
ditional Specimens of Eozoon,
52.
Loganite in Eozoon, 36, 102.
Lowe, Mr., referred to, 38.
Long Lake, Specimens from, 91.
Lyell, Sir C, on Eozoon, 234.
Madoc, Specimens from, 132.
Maps of Laurentian, 7, 16.
MacMullen, Mr,, referred to, 37.
Metamorphism of Rocks, 13,34.
Mineralization of Eozoon, 101 ; of
Fossils, 93 ; Hunt on, 115.
Nicholson on Stromatopora, 165.
Nummulites, 73.
Nummuline WaU, 43, 65, 106, 176,
181.
Objections answered, 169, 188.
Firkeria, 164.
Petite Nation, 20, 43.
Pole Hill, Specimens from, 121.
Proper WaU, 43, 65, 106, 176, 181.
Preservation of Eozoon, 93.
Protozoa, their Nature, 59, 207.
Pseudomorphism, 200.
Pyroxene filhng Eozoon, 108.
Red Clay of Pacific, 222.
Red Chalk, 222.
Reply to Objections, 167, 188.
Receptaculites, 162.
Robb, Mr., referred to, 120.
Rowney, Prof., Objectionfa of, 184.
Serpentine mineralizing Eozoon,
102.
INDEX.
239
Silicates mineralizing Fossils, 100,
103, 121, 220.
Silurian Fossils infiltrated with
Silicates, 121.
Steinhag, Eozoon of, 146.
Stromatopora, 37, 156.
Stromatoporiclse, 165.
Supplemental Skeleton, 64.
Table of Formations, G.
Trinity Cape, 10.
Tubuli Explained, 66, 106.
Varieties of Eozoon, 135, 236.
Vennor, Mr., referred to, 46, 57.
Wentworth Specimens, 91.
Weston, Mr., referred to, 20, 40,
162.
Wilson, Dr. , referred to, 36.
Worm-burrows in the Laurcntian,
133, 139.
I^itlor & Tiimier. Tlie Selwuoil rrliitiiiif Works Frunie. aiul Loiiilou