life is dawn on the earth 24

life is dawn on the earth 24

Some species of the Cœnostroma group have very dense calcareous

laminæ 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 Eozoon, or of Limestones supposed to contain it.

 

In Canada the principal localities of Eozoon Canadense are at

Grenville, Petite Nation, the Calumets Rapids, Burgess, Tudor, and

Madoc. At the two last places the fossil occurs in beds which may be

on a somewhat higher horizon than 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 specimen from this place is remarkable from having been

mineralized in part by a talcose mineral associated with serpentine.

 

I have examined specimens from Chelmsford, in Massachusetts, 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.

 

In 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 structures.

 

[Illustration:

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 laminæ of serpentine giving way. The dark band at one side is

one of the deep lacunæ or oscula.]

 

 

 

 

CHAPTER VII.

 

OPPONENTS 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 propose 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 regarding the

structures as organic. The reader who desires to appreciate this may

consult the notes to this chapter.[AN]

 

[Footnote AN: Also Rowney and King's papers in _Journal Geological

Society_, August, 1866; and _Proceedings Irish Academy_, 1870 and 1871.]

 

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 have much knowledge of the structure of foraminiferal

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 mineralisation.

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 preserved 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 illustrations accompanying them. It may nevertheless be

profitable to review some of the points referred to, and to present

some considerations making the existence of Laurentian life less

anomalous than may at first sight be supposed. One of these is the

fact that the discovery of Eozoon brings the rocks of the Laurentian

system into more full harmony with the other geological formations. It

explains the origin of the Laurentian 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 present, 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

complex 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 Palæozoic 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 discovery. It is not

very long since the old and semi-metamorphic sediments constituting the

great Silurian and Cambrian systems were massed together in geological

classifications as primitive or primary rocks, destitute or nearly

destitute of organic remains. The 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 Palæozoic 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, like

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

culmination 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 Primordial 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 Huronian 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 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 carbonic 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 comparison already instituted by Professor

Huxley and Dr. Carpenter, between the conditions of the Laurentian 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 Bavaricum_ of

Gümbel, the gap now existing between the life of the Lower Laurentian

and that of the Primordial 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 life 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 Eozoon for the

first fossil of the Laurentian, and in suggesting for the 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 chapters? I can fancy that this might be the first consequence,

more especially if the investigations were in the hands of persons

more conversant with minerals than with fossils; but I see no reason