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Fan, 5, 1871] 

NATURE 
185 

extremely busy, and the ultimate success of our operations must 
in a great measvre be attributed to the unremitting energy of 
Mr. Lockyer and Prof. Roscoe. 
Up till to-day the weather has been superb, day after day just 
like the warm days we often have in England towards the end 
of June. The thermometer in the shade has reached from 75° 
to 80° F., while the barometer has been steady, but with 
just sufficient tendency downward, to fill with gloomy appre- 
hension the less sanguine of our party. During this afternoon 
things do not look well, heavy clouds have been sailing over head, 
and have quite shrouded the upper five thousand feet of Etna; 
but we have yet hope, and all we can do is to wait patiently for 
about twenty hours, hoping then to get at least a bright gleam for 
the space of a minute and ahalf. If the sky so far favour us 
doubtless to-morrow will be an epoch in the history of astronomy. 
L. CUMMING 
Catania, Sicily, Dec. 21, 1870 
The Eclipse 
A REMARKABLE phase in the 
moon’s passage across the sun was 
the perfect apparent contact of the 
limb of the moon with a sun-spot, 
of which the annexed figure is a fair 
representation. The noticeable 
thing was that the body of the moon 
itself and the sun spots were of so 
precisely the same tint that no trace 
of a division was perceptible, one 



as long as the contact lasted. 
Exeter, December 22, 1870 W. F. 
Eozoon Canadense 
THE letter of Mr. T. Mellard Reade on the subject of 
Loz0bn Canadense, contained in your number for December 22, 
exhibits so complete a misapprehension of the state of our 
knowledge of that fossil, that I feel it necessary to break the 
silence which I have for some time imposed upon myself as re- 
gards this subject, in order that your readers may not be misled 
by the positiveness of his assertions. 
1. Mr. Reade speaks of Eozoén, with the exception of the 
‘Tudor specimen, as having been obtained only from metamor- 
hosed rocks. Yn reply to this, I have to state that the Eozodnal 
structure is most characteristically displayed in those portions of 
the Serpentine Limestone of the Laurentian formation which 
have undergone the /eust metamorphic change. In fact, the 
Calcareous lamellz of the best specimens of Eozoén in my 
possession show less departure from the shelly texture with which | 
Ihave become familiarised by the special study of the micro- 
scopic appearances of Shell, &c., for more than thirty years, than 
do the great majority of undoubted shells, corals, &c., contained 
in the least altered rocks of any geological period. 
2. Mr. Reade assumes that the presence of the Serpentine 
lamella, which alternate with the Calcareous lamelle, is itself an 
indication of metamorphic action. This position can only be 
sustained by those who are ignorant of the processes which can 
be shown to be at present going on upon the sea-bottom, and of 
which we haye evidence in various geological periods; whereby 
the sarcodic substance of animals of various types of organisa- 
tion, but especially of Foraminifera, undergoes replacement by 
siliceous compounds precipitated from sea-water during its de- 
composition. It was long since shown by Prof. Ehrenberg, that 
green sands of various ages, from the Silurian to the Cretaceous, 
are essentially formed of the iz¢ernal casts of Foraminifera. The 
late Prof. Bailey (U.S.) first proved that the production of such 
internal casts is taking place at the present time. I have long 
had in my possession a set of beautiful internal casts of this 
kind, procured from the late Mr. J. Beete Jukes’s dredgings on 
the coast of Australia. And quite recently I have obtained from 
Captain Spratt’s dredgings in the A°gean a most remarkable series 
of such casts, which includes representations in green and 
ochreous Silicates, not merely of the sarcode-bodies of Forami- 
nifera, but also of the sarcodic network that occupies the inter- 
spaces of the calcareous reticulation which I demonstrated 
twenty-three years ago (Brit. Assoc. Report for 1847) to be the 
appearing to be merged in the other | 
| the present time in the case of 

| doubtedly Mineral structures. 

basis of the skeleton throughout the class of Zchinodermata. 
And Dr. Duncan has shown that a like process is taking place at 
: Corals ; their animal substance 
being replaced by Silicates, whilst their Calcareous skeleton Te- 
mains unchanged. No mechanical agency can account for this 
replacement. It is not effected by the percolation of Silicates in 
solution, under the ‘‘ hydrothermal” action which Mr. Reade 
(following the lead of Messrs. King and Rowney) invokes as 
haying been concerned in the production of the Canadian Eozoén. 
And I am justified by the opinion of several of our ablest Chemists 
and Mineralogists in the assertion that no agency save a pro- 
| gressive chemical substitution can account for the production of 
these wonderful models ; the Silicates being precipitated from 
sea-water by the decomposition of the sarcodic substance which 
they replace and represent. Whether or not this doctrine be 
accepted, it may be confidently affirmed that whatever be the 
agency concerned in ¢he/r production, the filling-up of the cavities 
of the Calcareous skeleton of Eozoén may bz fairly accounted 
for in the same manner. 
3. The most characteristic features of the best-preserved 
specimens of the Canadian Eozoén can thus be completely 
paralleled by those of analogous formations at present going on. 
Let us suppose that the North Atlantic sea-bed, instead of being 
covered by minute individualised Globigerine, were occupied by 
a shell-producing Rhizopod having the indefinite extension of 
Bathybius, and that its sarcodic substance came to bz replaced (as 
| in the instances just cited) by Silicates precipitated from sea- 
water ; such a composite formation, elevated so as to become a 
terrestrial rock, wthout any metamorphism whatever, would be 
the precise parallel of the Zozed Canadense. And just as, at the 
present time, the replacing minerals are not always the same, 
though always compounds of Silica, so the substituted material in 
Eozo6n often consists of other minerals than Serpentine, always, 
however, being Silicates, In fact it was the zziformity of 
Morphological character, with variety of Mineral composition, 
that first led Six William Logan—a geologist second to none in 
experience and judgment—to the suspicion of its organic origin. 
4. Mr. Reade represents me as haying made ‘‘the important 
admission ” that ‘the several features in the structure of Eozoon 
(chamber-casts, canal-system, and proper walls) could be 
separately paralleled elsewhere,” meaning, I presume, in un- 
I have nowhere, thzt I can 
recollect, made any such admission: on the contrary, I have re- 
peatedly argued that whilst the comdination of structural 
characters in Fozoén affords the most unmistakeable evidence to 
those whose previously acquired knowledge enables them to 
appreciate their value, there are individual features which are in- 
consistent with any conceivable hypothesis of its purely Mineral 
character. Of these I may here state two, which I have always 
found to be most convincing to such as are familiar with the 
microscopic appearances of Minerals: Fivs¢, the fact that the 
““canal-system’’ which traverses the Calcareous lamellz passes 
| across their cleavage-planes, instead of defzucen them ; and that 
this canal-system has precisely the same distribution, whatever 
may be the mineral which occupies its tubes, whilst its finest 
ramifications are frequently filled with calcite, as in the least- 
altered fossil Foraminifera. The idea that such arborescent ex- 
pansions can have been produced by any kind of infiltration of 
one mineral into another, is thus, in the judgment of some of the 
most eminent Mineralogists of the day, altogether untenable ; 
whilst the precise Parallelism pointed out by Dr. Dawson, between 
the canal-system of Eozoon and that which I had shown to exist 
in the recent Ca/carina, is no less satisfactory to Naturalists con- 
versant with Foraminiferal structure. Second, the fact that the 
“© Nummuline layer ” or ‘* proper wall” of the chambers consists 
of a Calcareous lamella traversed by Siliceous aciculi, which 
sometimes lie siraight and parallel, are sometimes curved, and 
sometimes penicillate ; the precise equivalent to this being shown 
in the chamber-walls of recent Foraminifera, when the pseudo- 
podia which occupied their tubuli during life have been replaced 
by Silicates. Iassert again, on the authority of Mineralogists of 
the highest eminence, that such an arrangement cannot be shown 
in any undoubted mineral, and that it cannot be attributed to any 
physical agency. To liken this ‘‘Nummuline layer” to 
Chrysotile or any similar modification of Serpentine, shows a 
misapprehension of its essentially composite structure. 
I cannot admit that the question of the Organic nature of 
the Canadian Eozo6n (if question it be) is in the least degree 
affected by the occurrence of Metamorphic rocks presenting more 
or less morphological resemblance to it, in combination with un- 
doubtedly Mineral characters. We should never think of deci- 
