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497. It has been hitherto only in the Laurentian Serpentine-Lime-
stone of Canada, that Eozoon has presented itself in such a state of pres-
ervation as fully to justify the assumption of its Organic nature. But
from the greater or less resemblance which is presented to this by Ser-
pentine-Limestones occurring in various localities, among strata that seem
the Geological equivalents of the Canadian Laurentians, it seems a justifi-
able conclusion that this type was very generally diffused in the earlier ages
of the Earth's history; and that it had a large (and probably the chief)
share in the production of the most ancient Calcareous strata, separat-
ing Carbonate of Lime from its solution in Ocean-water, in the same
manner as do the Polypes by whose growth Coral-reefs and islands are
being upraised at the present time.

An elaborate work, " Der Bau des Eozoon Canadense" (1878) has been re-
cently published by Prof. Mobius of Kiel, in which the structure of Eozoon is
compared with that of various types of Foraminifera, and, as it differs from
that of every one of them, is affirmed not to be organic at all, but purely Min-
eral. Upon this the Author would remark, that if the validity of this mode of
reasoning be admitted, any Fossil whose structure does not correspond with that
of some existing type, is to be similarly rejected. Thus, the Stromatopora of
Silurian and Devonian rocks, which some Palaeontologists regard as a Coral,
others as Polyzoary, others as a Calcareous Sponge, and others as Foraminifer,
would not be a fossil at all, because it differs from every known living form.
Yet the suggestion that it is of Mineral origin would be scouted as absurd by
every Palaeontologist. Agai*, it is urged by Prof. Mobius that as the supposed
canal-system of Eozoon has not the constancy and regularity of distribution which



FORAMLNTFERA AND RADIOLARIA. 10T

it presents in existing Foraminifera, it must be accounted a Mineral infiltration.
To this the Author would reply: (1) That a prolonged and careful study of this
'canal-system,' in a great variety of modes, with an amount of material at his
disposal many times greater than Prof. Mobius could command, has satisfied him
that in well-preserved specimens the canal-system, so far from being vague and
indefinite, has a very regular plan of distribution; (2) That this plan does not
differ more from the arrangements characteristic of the several types of existing
Foraminifera, than those differ from each other,. its general conformity to them
being such as to satisfy Prof. Max Schultze (one of the ablest Foraminiferalists
of his time) of its Foraminiferal character; and (3) that not only does the distri-
bution of the canal-system of Eozoon differ in certain essential features from
every form of Mineral infiltration hitherto brought to light, but that canal-sys-
tems in no respect differing from each other in distribution are occupied by dif-
ferent minerals, a fact which seems conclusively to point to their pre-existence
in the Calcareous layers, and the subsequent penetration of these minerals into
the passages previous occupied by sarcode, precisely as has happened in those
* internal casts ' of existing Foraminifera ( 497) which Prof. Mobius altogether
ignores.

The argument for the Foraminiferal nature of Eozoon is essentially a cumula-
tive one, resting on a number of independent probabilities, no one of which, taken
separately, has the cogency of & proof ; yet the accordance of them all with that
hypothesis has an almost demonstrative value, no other hypothesis accounting at
once for the whole assemblage of facts. As it is the Author's intention to set
forth this in the best and completest form he can devise, at the earliest possible
period, he would beg for a suspension of judgment on the part of those who have
credited Prof. Mobius with having completely settled the question; the small
amount of evidence contained in his Memoir bearing no comparison to that of an
opposite bearing of which the Author is in possession.

498. Collection and Selection of Foraminifera. Many of the Forami-
nifera attach themselves in the living state to Sea -weeds, Zoophytes, etc. ;.
and they should, therefore, be carefully looked-for on such bodies, espe-
cially when it is desired to observe their internal organization and their
habits of life. They are often to be collected in much larger numbers,
however, from the sand or mud dredged-up from the sea-bottom, or even
from that taken from between the tide-marks. In a paper containing
some valuable hints on this subject, 1 Mr. Legg mentions that, in walking
over the Small-mouth Sand, which is situated on the north-side of Port-
land Bay, he observed the sand to be distinctly marked with white
ridges, many yards in length, running parallel with the edge of the
water; and upon examining portions of these, he found Foraminifera in
considerable abundance. One of the most fertile sources of supply that
our own coasts afford, is the ooze of the Oyster-beds, in which large-
numbers of living specimens will be found; the variety of specific forms,
however, is usually not very great. In separating these bodies from the
particles of sand, mud, etc., with which they are mixed, various methods
may be adopted, in order to shorten the tedious labor of picking them
out, one by one, under the Simple Microscope; and the choice to be
made among these will mainly depend upon the condition of the Foram-
inifera, the importance (or otherwise) of obtaining them alive, and the
nature of the substances with which they are mingled. -"Thus, if it be
desired to obtain living specimens from the oyster-ooze, for the examina-
tion of their soft parts, or for preservation in an Aquarium, much
time will be saved by stirring the mud (which should be taken from the
surface only of the deposit) in a jar with water, and then allowing it to-
stand for a few moments; for the finer particles will remain diffused
though the liquid, while the coarser will subside; and as the Forami-
nifera (in the present case) will be among the heavier, they will be found

1 " Transaction of Microscopical Society," 2d Series, Vol. ii. (1854), p. 19.



108 THE MICROSCOPE AND ITS REVELATIONS.

at the bottom of the vessel with comparatively little extraneous matter,
:after this operation has been repeated two or three times. It would
always be well to examine the first deposit let fall by the water that has
been poured-away; as this may contain the smaller and lighter forms of
Foraminifera. But supposing that it be only desired to obtain the dead
shells from a mass of sand brought-up by the dredge, a very different
method should be adopted; The whole mass should be exposed for
some hours to the heat of an oven, and be turned-over several times,
until it is found to have been thoroughly dried throughout; and then,
after being allowed to cool, it should be stirred in a large vessel of
water. The chambers of their shells being now occupied by air alone
(for the bodies of such as were alive will have shrunk-up almost to
nothing), the Foraminifera will be the lightest portion of the mass; and
they will be found floating on the water, while the particles of sand, etc.,
subside. Another method, devised by Mr. Legg, consists in taking ad-
vantage of the relative sizes of different kinds of Foraminifera and of
the substances that accompany them. This, which is especially applica-
ble to the sand and rubbish obtainable from Sponges (which may be got
in large quantity from the sponge-merchants), consists in sifting the
whole aggregate through successive sieves of wire-gauze, commencing
with one of 10 wires to the inch, which will separate large extraneous par-
ticles, and proceeding to those of 20, 40, 70, and 100 wires to the inch,
each (especially that of 70) retaining a much larger proportion of Foram-
iniferal shells than of the accompanying particles; so that a large portion
of the extraneous matter being thus got rid of, the final selection becomes
comparatively easy. Certain forms of Foraminifera are found attached
to Shells, especially bivalves (such as the Chamacece) with foliated sur-
faces; and a careful examination of those of tropical seas, when brought
home ' in the rough,' is almost sure to yield most valuable results. The
final selection of specimens for mounting should always be made under
some appropriate form of Single Microscope ( 43-48); a fine camel-
hair pencil, with the point wetted between the lips, being the instrument
which may be most conveniently and safely employed, even for the most
delicate specimens. In mounting Foraminifera as Microscopic objects,
the method to be adopted must entirely depend upon whether they are
to be viewed by transmitted or by reflected light. In the former case it^
should be mounted in Canada balsam ( 210); the various precautions to
prevent the retention of air-bubbles, which have been already described,
being carefully observed. In the latter no plan is so simple, easy, and
effectual, as the attaching them with a little gum to wooden slides (Fig.
124). They should be fixed in various positions, so as to present all the
different aspects of the shell, particular care being taken that its mouth
is clearly displayed; and this may often be most readily managed by at-
taching*the specimens sideways to the wall of the circular depression of
the slide. Or -the specimens may be attached to disks fitted for being
held in Morris's Disk-holder (Fig. 95); whilst for the examination of
specimens in every variety of position, Mr. R. Beck's Disk-holder (Fig.
94) will be found extremely convenient. Where, as will often happen,
the several individuals differ considerably from one another, special care
should be taken to arrange them in series illustrative of their range of
variation and of the mutual connections of even the most diverse forms.
For the display of the internal structure of Foraminifera, it will often
be necessary to make extremely thin sections, in the manner already de-
scribed ( 192-194); and much time will be saved by attaching a nunv



FORAMINIFERA AND RADIOLARIA.

ber of specimens to tlie glass slide at once, and by grinding them down
together ( 192, note). For the preparation of sections, however, of the
extreme thinness that is often required, those which have been thus
reduced should be transferred to separate slides, and finished-off each one
by itself.

KADIOLAHIA.

499. It has been shown that one series of forms belonging to the
Rhizopod type is characterized by the radiating arrangement of their rod-
like pseudopodia ( 399), suggesting the designation Heliozoa or ' sun-ani-
malcules;' and that even among those fresh- water forms that do not depart
widely from the common Actinophrys (Fig. 285), there are some whose-
bodies are inclosed in a complete siliceous skeleton. Now just as the

Flo. 345.




Fossil Radiolaria from Barbadoes. a, Podocyrtis mitra; 6, Rhabdolithus sceptrum; c, Lych-
nocanium falciferum; d, Eucyrtidium tubulus; e, Flustrellaconcentrica;/, Lychnocaniumlucerna;
</, Eucyrtidium elegans; 7i, Dictyospyris clathrus; i, Eucyrtidium Mongolfieri; k, Stephanolithis
spinescens; I, S. nodosa; m, Lithocyclia ocellus; n, Cephalolithis sylvina; o, Podocyrtis cothur-
nata; p, Rhabdolitlius pipa.

Eeticularian type of Khizopod life culminates in the marine calcareous-
shelled Foraminifera, so does the Heliozoic type seem to culminate in
the marine Radiolaria; which, living for the most part near the surface
of the ocean, form siliceous skeletons (often of marvellous symmetry and
beauty), that fall to the bottom on the death of the animals that pro-
duced them, and may remain unchanged, like those of the Diatoms,
through unlimited periods of time. Some of these skeletons, mingled
with those of Diatoms, had been detected by Prof. Ehrenberg in the
midst of various deposits of Foraminiferal origin, such as the Calcareous
Tertiaries of Sicily and Greece, and of Oran in Africa; and he established
for them the group of Polycystina, to which he was able also to refer a
beautiful series of forms making-up nearly the whole of a siliceous



110 THE MICROSCOPE AND ITS REVELATIONS.

sandstone prevailing through an extensive district in the island of Bar-
badoes (Fig. 345). Nothing, however, was known of the nature of the
.animals that formed them, until they were discovered and studied in the
living state by Prof. J. Miiller; 1 who established the group of Radiolaria,
including therein, with the Polycystina of Ehrenberg, the Acanthome-
trina ( 505) first recognized by himself, and the Thalassicolla ( 506)
which had been discovered by Prof. Huxley. Not long afterwards ap-
peared the magnificent and ( epoch-making* work of Prof. Haeckel; 9 and
since that time much has been added by various observers to our knowl-
edge of this group, which still remains, however, very imperfect. For
the following general account of its characters, the Author is indebted to
the valuable summary of " Recent Researches in regard to the Radio-
laria " lately given by Prof. Mivart. 8

500. Each individual Radiolarian consists of two portions of colored
or colorless sarcode: one portion nucleated and central; the other portion
peripheral, and almost always containing certain yellow corpuscles.
These two portions are separated by a chitinous membrane called the
capsule ; but this is so porous as to allow of their free communication
with each other. The yellow corpuscles seem to be true ' cells;' having
a regular membranous wall, with protoplasmic contents (including
starch-granules), and distinct nuclei; and multiplying themselves by sub-
division. But there is considerable doubt whether they are really parts
of the animal body, as they have been found in vigorous life when the
rest of the animal is dead and decaying; and they are regarded by Cien-
kowski as parasites. The pseudopodia radiate in all directions (Plate
xviii., figs. 3, 4) from the deeper portion ol the extra-capsular sarcode;
they have generally much persistency of direction, and very little flexi-
bility; in some species (b\it not ordinarily) they branch and anastomose;
while in others they are inclosed in hollow rods that form part of the
siliceous skeleton, and issue forth from the extremities of these. A flow
of granules takes place along them; and the mode in which they obtain
food-particles (consisting of Diatoms and other minute Algae, marine In-
fusoria, etc.), and draw them into the sarcode-bodies of the Radiolarians,
appears to correspond entirely with their action in Actinophrys and
other Heliozoa ( 399).

501. In most Radiolaria, skeletal structures are developed in the sar-
code-body, either inside or outside the capsule, or in both positions; some-
times in the form of investing networks having more or less of a spheroi-
dal form (Plate xix., figs. 1, 2), or of radiating spines (fig. 3), or .of
combinations of these (figs. 4, 5). But in many cases the skeleton con-
sists only of a few scattered spicules; and this is especially the case in
certain large composite forms or ' colonies ' (Fig. 350) which may consist
of as many as a thousand zooids, aggregated together in various forms,
discoidal, cylindrical, spheroidal, chain-like, or even necklace-like. The
' colonies ' seem to be produced, like the multiple segments of the bodies
of Foraminifera ( 456); by the non-sexual multiplication of a primordial
zooid; but whether this multiplication takes place by fission, or by the
budding-off of portions of the sarcode-body, has not yet been clearly

1 ' Ueber dieThalassicollen,Polycystinen\ind Aeanthometren des Mittelmeeres,'
In " Abhandlungen der Konigl. Akad. der Wissensch. zu Berlin," 1858, and sepa-
rately published; also ' Ueber die im Hafen von Messina beobachteten Polycysti-
nen' in the " Monatsberichte " of the Berlin Academy for 1S55, pp. 671-67(5.

*"Die Radiolarien (Rhizopoda Radiaria)," Berlin, 1862.

3 " Journal of the Linneean Society," Vol. xiv. (Zool.), p. 136.



FORAMINIFERA AND RADIOLARIA.



Ill



PLATE XV1IL

FtO. 1. FlO. 2





Fro. 3.




VARIOUS FORMS OF poLYCYSTiNA (after Ehrenberg).

Fig. 1. Podoyrtis Schomburgkii.

2. Rhopalocanium ornatum.

3. Haliomma hystrix.

4. Pterocanium, with animal.



112



THE MICROSCOPE AND ITS KEVELATIO.NS.



made-out. The emission of flagellated zoospores, very similar to those
of Clatlirulina (Fig. 288), has been observed in many Kadiolarians; but
of the mode in which they are produced, and of their subsequent history,
very little is at present known. Until the structure and life-history of
the animals of this very interesting type shall have been more fully elu-
cidated, no satisfactory classification of them can be framed; and nothing
more will be here attempted than to indicate some of the principal forms
under which the Radiolarian type presents itself.

502. Discida. Among the beautiful siliceous structures which are met
with in the Radiolarian sandstone of Barbadoes (Fig. 345) there is none
more interesting than the skeleton of Astromma (Fig. 340) ; in which we
have a remarkable example of the range of variation that is compatible
with conformity to a general plan of structure. As in other forms of
Haeckel's group of Discida, there is in this skeleton a combination of



FIG. 346




Varietal modifications of Astromma.

radial and of circumferential parts; the former consisting of solid spoke-
like rods, whilst the latter is composed of a siliceous network more or
less completely filling up the spaces between the rays. The radial part
of the skeleton predominates in the beautiful 4-rayed example represented
at D, having the form of a Maltese cross; whilst in F and G it still shows
itself very conspicuously, though the spaces between the rays are in great
part filled up by the circumferential network. In the 5-rayed specimens
A and B, on the other hand, the radial portion is much less developed,
whilst the circumferential becomes more discoidal. And in c and E,
while the circumferential network forms a pentagonal disk, the radial
portion is represented only by solid projections at its angles. The transi-
tion between the extreme forms is found to be so gradual when a number
of specimens are compared, that no lines of specific distinction can be
drawn between them; and the difference in the number of rays is probably



FORAMINIFERA AJ*D RADIOLARIA.



113



of no more account in these low forms of Animal life, than it is in the
discoidal Diatoms ( 290). Other discoidal forms, showing a like com-
bination of radial and circumferential parts are represented in Figs. 347
and 348, and also in Fig. 345, e, m.

503. Entosphcerida. In this group the siliceous shell is spheroidal,
and is formed within the capsule; and it is not traversed by radii, al-
though prolongations of the shell often extend themselves radially out-
wards, as in Cladococcus (Plate xix., fig. 5). Sometimes the central
sphere is inclosed in two, three, or even more concentric spheres con-
nected by radii, as in the beautiful Actinomma (Plate xix., fig. 2);
reminding us of the wonderful concentric spheres carved in ivory by the
Chinese. One of the most common examples of this group is the Hali-
omma Humboldtii (Fig. 349), in which the shell is double.

504. Polycystina. This name, which originally included the pre-
ceding group, is now restricted to those which have the shell formed
outside the capsule. This shell may, as in the preceding, be a simple,
sphere composed of an open siliceous network, as in Etlimo splicer a, (Plate
xix., fig. 1); or it may consist of two or three concentric spheres con-
nected by radii; or, again, it may put forth radial outgrowths, which



FIG. 34T.



FIG. 348.





Perichlamydium prcetextum.



Stylodyctya gracHis.



sometimes extend themselves to several times the diameter of the shell,
and ramify more or less minutely, as in Arachno splicer a (Plate xix., fig.
4). But more frequently the shell opens-out at one pole into a form
more or less bell-like, as in Podocyrtis (Plate xvin., fig. 1, and Fig. 345,
, o), Rhopalocanium (Plate xvm., fig. 2), and Pterocanium (Plate xvni.,
fig. 4); or it may be elongated into a somewhat cylindrical form, one
pole remaining closed, while the other is more or less contracted, as in
Eucyrtidium (Fig. 345, d, g, i). The transition between these forms
again, proves to be as gradational, when many specimens are compared, 1
as it is among Foraminifera ( 488).

505. Acantlwmetrina. In this group the animal is not inclosed with-
in a shell, but is furnished with a very regular skeleton composed of
elongated spines, which radiate in all directions from a common centre
(Plate xix., fig. 3). The soft sarcode-body is spherical in form, and
occupies the spaces left between the bases of these spines, which are some-
times partly inclosed (as in the species represented) by transverse projec-

1 The general Plan of structure of the Polycystina, and the signification of
their immense variety of forms, were ably discussed by Dr. Wallich, in the
"Trans, of the Microsc. Soc., ' N.S., Vol. xii. (1865), p. 75.
8



114 THE MICROSCOPE AND ITS REVELATIONS.





PLATE XIX.







VAKIOTTS FORMS OF RADioLAMA (after Haeckel).

Fig. 1. Ethmosphcera siplionophora.

2. Actinomma inerme.

3. Acanthometro xiphicantha.

4. Arachnosphcera obligacantha.

5. Cladococcus viminalis.



FORAMINIFERA AND RADIOLARIA.



115



tions. The e capsule ' is pierced by the pseudopodia, whose convergence
may be traced from without inwards, after passing through it; and it is
itself enveloped in a layer of less tejiacious protoplasm, resembling that
of which the pseudopodia are composed. One species, the Acantliometra
echinoides, which presents itself to the naked eye as a crimson-red point,
the diameter of the central part of its body being about 6-1000ths of an
inch, is very common on some parts of the coast of Norway, especially
during the prevalence of westerly winds; and the Author has himself
met with it abundantly near Shetland, in the floating brown masses
termed madre by the fishermen (who believe them to furnish food to the
herring), which consist mainly of this Acanthometra mingled with
Entomostraca.

506. Cpllozoa. To this group belong these remarkable composite
forms, which, exhibiting the characteristic Radiolarian type in their indi-
vidual zooids, are aggregated into masses in which the skeleton is repre-



Fio. 349.



FIG. 350.





Haliomma Humboldtii.



Sphcerozoum ovodimare.



sented only by scattered spicules, as in Sphcerozoum (Fig. 350) and
Thalassicolla. These ' sea-jellies/ which so abound in the seas of warm
latitudes as to be among the commonest objects collected by the Tow-net,
are small gelatinous rounded bodies, of very variable size and shape, but
usually either globular or discoidal. Externally they are invested by a
layer of condensed sarcode, which sends forth pseudopodial extensions
that commonly stand out like rays, but sometimes inosculate with each
other so as to form network. Towards the inner surface of this coat are
scattered a great number of oval bodies resembling cells, having a toler-
ably distinct membraniform wall and a conspicuous round central nucleus.
Each of these bodies appears to be without any direct connection with
the rest; but it serves as a centre round which a number of minute yel-
lowish-green vesicles are disposed. Each of these groups is protected by
a siliceous skeleton, which sometimes consists of separate spicules (as in
Fig. 350), but which may be a thin perforated sphere, like that of cer-
tain Polycystina, sometimes extending itself into radial prolongations.



116 THE MICROSCOPE AND ITS REVELATIONS.

The internal portion of each mass is composed of an aggregation of large
vesicle-like bodies, imbedded in a softer sarcodic substance. 1

507. From the researches made (Juring the 'Challenger' expediti* n,
it appears that the Radiolaria are very widely diffused through the waters
of the ocean, some forms being more abundant in tropical and others in
temperature seas; and that they live not only at or near the surface, but
also at considerable depths. Their siliceous skeletons accumulate in some
localities (in which the calcareous remains of Foraminifera are wanting)
to such an extent as to form a 'Kadiolarian ooze;' and it is obvious that
the elevation of such a deposit into dryland would form a bed of siliceous
sandstone resembling the well-known Barbadoes rock, which is said to
attain a thickness of 1100 feet, or a similar rock of yet greater thickness
in the Nicobar Islands. Few Microscopic objects are more beautiful



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