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TRANSACTIONS

MICROSCOPICAL SOCIETY |

LONDON.

NEW SERIES.

eee

VOLUME I.

LONDON:
SAMUEL HIGHLEY, 32, FLEET STREET.
i 1853.

FEB T2 \eas

L1Q2a4RN

LONDON: PRINTED BY W. CLOWES AND SONS, STAMFORD STREET.

- 978.0642
RSS
Sr

——

xy! TRANSACTIONS

OF THE

MICROSCOPICAL SOCTETY

OF

LONDON.

hess

Lacinutaria sociaLis. A Contribution to the Anatomy and
Physiology of the Rotvirera. By T. H. Huxtey, Esq.,
F.R.S., Assist.-“Surgeon R.N. (Read Dec. 31, 1851.)

Tue leaves of the Ceratophyllum, which abounds in the river
Medway, a little above Farleigh Bridge, are beset with small
transparent, gelatinous-looking, globular bodies, about 1-5th
of an inch in diameter. ‘These are aggregations of a very
singular and beautiful Rotifer, the Lacinularia socialis of
Ehrenberg. On account of their relatively large size, their
transparency, and their fixity, they present especial advantages
for microscopic observation ; and I therefore gladly availed
myself of a short stay in that part of the country to inquire
- somewhat minutely into their structure, in the hope of being
able to throw some light on the many doubtful or disputed
points of the organization of the class to which they belong.
We are told by Ehrenberg (‘Infusions-Thierchen,’ p. 403)
that Lacinularia socialis was discovered and described
anonymously in Berlin in 1753. Miller bestowed upon it

wheldony “4e5 ley

al the name of Vorticella socialis, which was changed by
o Schweigger to Lacinularia in 1820. Previously to the time
— of Ehrenberg the genus appears to have become confounded

with Megalotrocha ; and indeed Dujardin very reasonably,
as it seems, altogether denies the propriety of their separa-
tion. The extreme resemblance of the two forms is admitted
by Ehrenberg himself; but he considers the attachment of
the ova of Megalotrocha by a filament to the body—a circum-
stance which does not obtain in Lacinularia—and the exist-
ence of a gelatinous investment in the latter which is not
found in the former, to be sufficient grounds of distinction.
The matter is not one of much importance, but I call
attention to the close alliance between Megalotrocha and
Lacinularia for a reason which will appear in the sequel.
The globular aggregations of which I have spoken are not
VOL. I. i b

2 Hux ey on Lacinularia socialis.

ramified animals like the freshwater Polyzoa, to which, at
first sight, they have no small resemblance, but may be truly
called compound animals, since each of the Lacinulari@ is a
separate individual, which at one time swam about freely by
itself,* which has voluntarily united itself with its fellows,
and has taken its share in throwing out the gelatinous sub-
stance which connects them into a whole.

Each Lacinularia (Pl. I. fig. 1) has an elongated conical
body, whose outer extremity is considerably the wider, and
whose inner smaller end is truncated, and serves as a sucker
or means of attachment to the stem on which the whole mass
is seated; the outer third or fourth of the body contains the
viscera, nothing but the muscular cords extending into the
inner narrow elongated part of the animal. During con-
traction the latter portion is thrown into sharp folds, while
the visceral portion presents only three or four faint transverse
constrictions.

When the Rotifer is in a state of expansion and activity,
its outer extremity is terminated by a large horseshoe-shaped
wheel-organ, or “trochal disc” (figs. 2, 3), connected with
the body by a narrowed neck. When contracted and at rest,
the whole of this apparatus is drawn in, and the body takes
on a more pyriform appearance (fig. 5).

The mouth lies in the notch of the trochal disc (fig. 4 d) ; the
anus is placed on the opposite side, at the lower part of the
visceral portion of the animal (A).

Anatomy of Lacinularia.—1 will now proceed to describe
the various organs of the animal more minutely.

The “trochal disc” is, as I have said, wide and horseshoe-
shaped. It is seen in profile at figs. 1 and 2; from above
at fig. 8. Its edges are richly beset with large cilia, which
present a very beautiful wheel-like movement.

Ehrenberg says that the ciliary organ is “as in Megalo-
trocha,’ and in this he describes the disc as having a simple
ciliated edge. I have not examined Megalotrocha, but I can
say most decidedly that such is not the structure of La-
cinularia.t

In fact, the edge of the disc has a considerable thickness,
and presents two always distinct margins—an upper (p) and

* Or rather had the power of swimming about freely; for it does not
appear that the young Lacinularic ever do leave the gelatinous envelope
of the parent mass, unless aggregated together.

+ Leydig (Zur Anatomie und Entwickelungs-geschichte der Lacinu-
laria socialis—Siebold and Kolliker’s Zeitschrift for February, 1852) says
that ‘‘an elevated ridge runs along the lower surface of the wheel organ,
not far from and parallel to its margin, whence there is a double edge and
a groove, In which alone ciliary motion is observed.”

Houxzey on Lacinularia socialis.- 3

a lower (p’), of which the former is the thicker and extends
beyond the latter.

The large cilia are entirely confined to the upper margin,
and, seated upon it, they form a continuous horseshoe-shaped
band, which, upon the oral side, passes entirely above the
mouth (fig. 4). The lower margin (p’) is smaller and less
defined than the upper, its cilia are fine and small, not more
than 1-4th the size of those of the upper margin. On the oral
_ side this lower band of cilia forms a V-shaped loop (fig. 4),

which constitutes the lower and lateral margins of the oral
aperture. About the middle of this margin, on each side,
there is a small prominence, from which a lateral ciliated
arch runs upwards into the buccal cavity, and, below, becomes
lost in the cilia of the pharynx.

The aperture of the mouth therefore lies between the
upper and lower ciliary bands. It is vertically elongated,
and leads into a buccal cavity with two lateral pouches, which
give it an obcordate form; these lateral pouches contain the
lateral ciliated arches. A narrow pharynx leads horizontally
backwards from the lower part of the buccal cavity, and
becomes suddenly widened to enclose the pharyngeal bulb in
which the teeth are set. Where buccal cavity meets the
pharynx, a sharp line of demarcation exists (fig. 2). In Meli-
certa two curved lines are seen in a corresponding position, and
evidently indicate two folds (PI. II. fig. 26), projecting upwards
into the csophagus. In Brachionus these folds are stronger
(fig. 31), while in Stephanoceros and Floscularia this partition
between the cesophagus and what may be called the crop is
still more marked. From the inner margin of the aperture
in the partition two delicate membranes hang down into the
cavity of the crop, which have a wavy motion, and it is to them
I think that what Mr. Gosse describes as an appearance of
“‘ water constantly percolating into the alimentary canal” is
due. Dujardin had already noticed (1. c, p. 98) these
“vibrating membranes” in Floscularia (‘ Infusoires,’ p. 611).

Between the pharyngeal bulb and the mouth there lies on
each side of the pharynx a clear, yellowish, horny-looking
mass (f), which sometimes appears merely cordate, at others
more or less completely composed of two lobes. A similar
structure exists in Brachionus and Melicerta. 1 believe its
function is to give strength to the delicate walls of the
pharynx, and that it is therefore to be considered as a part of
the horny skeleton.*

* Leydig (loc. cit.) calls these bodies sacs, and considers them to be
salivary glands.
b2

4 Hoxtey on Lacinularia socialis.

The general nature of the pharyngeal bulb and of its
movements has been so often described that it is needless
for me to refer to the subject here. With regard to the teeth,
however, what I have seen is considerably at variance with
the accounts of both Ehrenberg and Dujardin; the former
calls the teeth of JZacinularia “reihenzaihnigen,” that is,
having a stirrup-like frame, with many teeth set upon it;
and the latter,in his general definition of the “ Melicertiens,”
under which head he places Lacinularia, has “machoires en
étrier” (‘ Hist. Nat. des Infusoires,’ p. 612).*

As I have seen it (fig. 6), the armature of the pharyngeal
bulb in this species—as in Stephanoceros—is composed of
four separate pieces. ‘Two of these (which form the incus
of Mr. Gosse) are elongated triangular prisms,} applied
together by their flat inner faces ; the upper faces are rather
concave, while the outer faces are convex, and upon these
the two other pieces (the mallei of Mr. Gosse) are articulated.
These last are elongated—concave internally, convex ex-
ternally—and present two clear spaces in their interior;
from their inner surface a thin curved plate projects inwards.
At its anterior extremity this plate is brownish, and divided
into five or six hard teeth, with slightly enlarged extremities.
Posteriorly the divisions become less and less distinct, and
the plate takes quite the appearance of the rest of the piece.

This is essentially the same structure as that of the teeth
of Notommata, described by Mr. Dalrymple (‘ Phil. Trans,’
1849), and by Mr. Gosse (on the Anatomy of Notommata
aurita, Mic. Trans. 1851), and very different from the true
“ stirrup-shaped ” armature.

A narrow oesophagus passes directly downwards from the
posterior part of the cavity of the pharyngeal bulb, through
the neck of the animal to the body, where it — into the
wide alimentary canal,

This is divided into three portions by an upper, a middle,
and a lower constriction.

The two upper parts are often not very distinctly divided.
A wide oval or pyriform sac, whose wall contains many nu-
cleated cells, opens into the upper portion on each side. This
is the “ pancreatic” sac of Ehrenberg.t

The middle dilatation frequently gives origin to several short
cellular cceca.

The lowest dilatation is globular, and has also several cel-

* Leydig also finds Ehrenberg’s figures “‘ untrue to nature.”

+ Not described by Leydig.

+ According to Leydig there are four of these bodies, two smaller and two
larger, and they do not open into the alimentary canal.—Loce, cit. .» p- 463.

Houxtey on Lacinularia socialis. ae

lular coeca projecting from its outer surface. Within it is
clothed with very long cilia.

The intestine is short and wide, and comparatively delicate ;
it bends suddenly upwards on the side opposite the mouth,
and terminates in a cleft of the integument, whose whole extent
it did not seem to me to occupy. (Fig. 1 2)

The Water Vascular System.—This system is thus loosely
and confusedly alluded to—I cannot call it described—by
Professor Ehrenberg :*—‘* The vascular system consists of
transverse circular canals in the body, a vascular network at
the base of the wheel-organ, with perhaps a broad circular
canal at this part, and of trembling gill-like bodies’’—(loc. cit.,
p- 403). The vascular system is so obvious,{ that it is diffi-
cult to understand how it can have been thus blurred over.

The reader will bear in mind that the two bands which run
up from the cloaca in many Rotifera, and are usually con-
nected at their extremity with a “ contractile vesicle,” while
they give attachment in their length to the “ trembling gill-
like organs” of Ehrenberg, are considered by the latter to be
the testes. He says that “ the trembling organs” appear to
be within the sac in Hydatina, outside it in Notommata.

Von Siebold (‘ Vergleichende Anatomie’) first pointed out
that a vessel runs up in each of these bands, and that the
‘* trembling organs’’ are short branches of these vessels, each
of which contains a vibrating ciliary band (Flimmer-lappchen),
to which the trembling appearance is due. According to Von
Siebold each of these vibrating bodies indicates an opening in
the vessel.

Oskar Schmidt (‘ Versuch einer Darstellung d. Organisation
d. Raderthiere-—Erichsons Archiv, 1846) asserts that the
ends of the water-vessels are closed, and that the vibrating
body is within them.

Dalrymple (loc. cit.) saw no testes in the lateral bands of
Notommata, and considers that the “ tags”’ (the ‘ trembling
organs” of Ehrenberg) are externally ciliated at their extre-
mities.

Mr. Gosse (‘ Microscopical Transactions,’ 1851) describes
the water-vascular system in Motommata aurita, and states
that the “ tags” of Ehrenberg are really pyriform sacs ; but
he seems not to have distinguished the contained cilium, at
least his description is ambiguous. ‘ When trembling mode-
rately they are seen to be little oval bags attached to the tor-
tuous vessel by a neck and sac at the other end. A spiral

* “T can thus affirm, that what Ehrenberg describes as vessels in
Lacinularia are in fact not vessels at all.”—Leydég, loc, cit., p. 468.
t ‘Sehr aus-gepract,” Leydig, p. 465.

6 Huxtey on Lacinularia socialis.

vessel, closed at the extremity, runs through most of its length,
which maintains a wavy motion”—p, 98.*

The following is what I have seen in Lacinularia :—There
is no contractile sac opening into the cloaca as in other genera,
but two very delicate vessels, about 1-4000th of an inch in dia-
meter, clear and colourless (fig. 3 m), arise by a common origin
upon the dorsal side of the intestine. Whether they open into
this, or have a distinct external duct, I cannot say.

The vessels separate, and one runs up on each side of sis
body towards its oral side (fig. 2). Arrived at the level of
the pharyngeal bulb, each vessel divides into three branches
(fig. 3); one passes over the pharynx and in front of the pha-
ryngeal bulb, and unites with its fellow of the opposite side,
while the other two pass, one inwards and the other outwards,
in the space between the two layers of the trochal disc, and
there terminate as coeca. Besides these there sometimes
seemed to be another branch, just below the pancreatic sacs.

A. vibratile body was contained in each of the ceecal
branches ; and there was one on each side in the transverse
connecting branch. Two more were contained in each lateral
main trunk, one opposite the pancreatic sacs, and one lower
down, making in all five on each side.

* M. Udekem (Annales des Sciences, 1851) has given a very elaborate,
but I think not altogether correct, account of the water-vascular system
of Lacinularia. He says that a vascular net-work exists at the base of the
lobes of the wheel-organ; that these unite into gland-like ganglia (my
** vacuolar thickenings,” in the margin of the disc infra) ; that from these,
vessels proceed to the central glands (vacuolar substance, in which the
“band” of the water-vascular system terminates, mihz), from which three
great vessels are given off. Of these, one “passes above the digestive
tube, and anastomoses with its fellow from the opposite ganglion ; the
second presents the same disposition as the first, but is placed below the
digestive tube; the third passes directly downwards, skirting the digestive
tube.” M. Udekem found it ‘‘impossible to trace it any further, but
considers that it becomes lost on the digestive canal and ovaries.” He,
therefore, has missed the external opening of the water-vascular system.

What I have seen and described as ‘‘ vacuolar thickenings” in the
peduncle, are described by M. Udekem as vascular ganglia, from which
anastomosing vessels proceed.

As M. Udekem’s instrument does not seem to have been good enough
to define the vibratile cilium—for he speaks only of a ‘‘ vibratile or trem-
bling movement”—I venture to think that he has been misled in describing
these threads and vacuolar thickenings as forming any part of the true
vascular system.

Leydig’s opinion of M. Udekem’s results is, I find, much the same as
my own. He says, ‘ Critically considered, then, we find that Udekem’s
vascular system in Lacinularia is compounded of a multitude of the most
heterogeneous parts of the animal—of structures which belong to the most
different systems of organs, without one being a true blood-vessel.”—L. c¢.,
p- 465.

Houxcey on Lacinularia socialis. ih.

Each of these bodies was a long cilium (1-1400th of an inch),
attached by one extremity to the side of the vessel, and by the
other vibrating with a quick undulatory motion in its cavity
(fig. 8). As Siebold remarks, it gives rise to an appearance
singularly like that of a flickering flame.

I particularly endeavoured to find any appearance of an
opening near the vibratile cilium, but never succeeded, and
several times I thought I could distinctly observe that no such
aperture existed. Animals that have been kept for some days
in a limited amount of water are especially fit for these re-
searches. ‘They seem to become, in a manner, dropsical, and
the water-vessels partake in the general dilatation.

‘The “ band” (fig. 7) which accompanies the vessel ap-
peared to me to consist merely of contractile substance, and to
serve as a mechanical support to the vessel. It terminates
above, in a mass of similar substance, containing vacuole,
attached to the upper plate of the trochal disc. I shall refer
to this and similar structures below.

I examined these structures so frequently that I have no

doubt that the account I have given is essentially accurate, *
and | am strengthened in this opinion by the account and
figure of the corresponding vessels in Mesostomum given by
Dr. Max Schulze, in his very beautiful monograph upon the
Turbellaria (Beitrage zur Naturgeschichte d. Turbellarien).
Through these the transition to the richly ciliated water-
vessels of the Naidz, &c., is easy enough.

Vacuolar Thickenings.—(figs. 2, 8 r). Under this head I in-
clude a series of structures of, as I believe, precisely similar
nature, which, on Professor Ehrenberg’s principles of interpre-
tation, have done duty as ganglia, testes, &c., in short, have
taken the place of any organ that happened to be missing.

In various parts of the body the parietes have become
locally thickened, and the prominences thus formed have

* Leydig’s careful description coincides in all essential points with that
given above. He particularly notices the fitness of Lacinulariz that have
been imprisoned for some time, for the examination of the water-vascular
system.

The only discrepancy of importance in Leydig’s account is—firstly, that
- he considers what I have called the ‘‘ vacuolar thickening on each side of
the pharyngeal mass,” and what Ehrenberg calls a nervous centre, to be
formed by convolutions of the water-vessel itself; and secondly, that he
describes a cloacal vesicle as in other Rotifera. I looked particularly for
such a vesicle, but could never see any ; in some cases, indeed, I could
- trace the water-vessels distinct from one another, close to the anus.

Beyond these particular cases, however, I will by no means venture to
contradict so accurate an observer as M. Leydig.

Leydig does not seem to have noticed the transverse anastomosing vessel
over the pharynx.

8 Hox ey on Lacinularia socialis.

developed many clear spaces, or vacuole—a histological pro-
cess of very common occurrence among the lower invertebrata.

Now these thickenings are especially obvious in two
localities—Ist, in the prolongation of the body below the
visceral cavity ;* and 2ndly, in the trochal disc.

Of the former thickenings, the four uppermost are pro-
moted by Professor Ehrenberg to be testes, for no other
reason, apparently, than that, having missed the true water-
vascular system with its bands, he knew not where else to
find what he calls a male organ.

Again, the thickenings (figs. 2, 37) in the trochal disc are
mostly towards its lower surface and at its inferior margin ;
they are generally four or five on each side, and are connected
by branched filaments with that body on each side of the
pharyngeal mass in which the band of the water-vascular
system terminates.

~According to Professor Ehrenberg these are all ganglia,
and the two yellowish bilobed or cordate bodies on each side
of the pharynx are “ comparable to a brain!”

Nervous System and Organs of Sense.{—On the oral side

* Leydig (loc. cit., p. 467-8) regards the central vacuolar mass at the
root of the tail as a peculiar gland, from which he says a duct runs down-
wards to terminate at the extremity of the tail. The purpose of this
organ is to secrete the gelatinous envelope. I must confess that I saw no
grounds for this interpretation. The extremity of the tail always seemed
to me to present a ciliated hemispherical cavity, closed above.

+ Leydig (1. c., p. 457 et seq.) criticises at length, and altogether re-
pudiates, the mythical nerves and ganglions which Professor Khrenberg
has ascribed to Lacinularia. He does not appear to have seen either the
ciliated cavity, or the body which I still venture to think is the only true
ganglion ; but describes a very peculiar nervous system, consisting of—

1. A ganglion behind the pharynx, composed of four bipolar cells, with
their processes.

2. A ganglion at the beginning of the caudal prolongation, similarly
composed of four larger ganglionic cells and their processes.

The latter cells are what I have described as vacuolar thickenings; I
could find no difference whatever between them and the thickenings in the
disc, which Leydig allows to be mere thickenings.

The former were not observed by me. I have not been able to repeat
my investigations upon this point, as ] hope to do ; for the present I must
offer as arguments against Leydig’s interpretation of the nature of the |
structures which he observed—

1st. That the body which I describe as a ganglion is perfectly similar
in appearance to the mass on which the eye-spots of Brachionus are seated.

2nd. That if such an arrangement of the nervous system as that which
Leydig describes exists, the Rotifera are very widely different from their
congeners, and, indeed, from all known animals.

Leydig himself, however, says,—‘‘ That these cells, with their radiating
processes, are ganglion-globules and nerves, is a conclusion drawn simply
from the histological constitution of the parts, and from the impossibility
of making anything else out of them, unless, indeed, organs are to be
named according to our mere will and pleasure.”—L. c., p. 459.

Huxtey on Lacinularia socials. Q -

of the neck of the animal, or rather upon the under surface of
the trochal disc, just where it joins the neck, and therefore
behind and below the mouth, there is a small hemispherical
cavity (fig. 40) (about 1-1400th of an inch in diameter), which
seems to have a thickened wall, and is richly ciliated within.
Below this sac, but in contact with it by its upper edge, is a
bilobed homogeneous mass (figs. 2 and 4 2) (about 1-800th
of an inch in diameter), resembling in appearance the ganglion
of Brachionus, and running into two prolongations below, but
whether these were continued into cords or not I could not
make out.

I believe that this is, in fact, the true nervous centre, and
that the sac in connection with it is analogous to the ciliated
pits on the sides of the head of the Nemertide, to the
“ciliated sac” of the Ascidians, which is similarly connected
with their nervous centre, and to the ciliated sac which
forms the olfactory organ of Amphiozus.

Mr. Gosse has described a similar organ in Melicerta
ringens, and | have had an opportunity of verifying his obser-
vations, with the exception of one point. According to this
observer, the cilia are continuous from the trochal disc into the
cup; so far as I have observed, however—and I paid par-
ticular attention to the point—the cilia of the cup are wholly
distinct from those of the disc.

The interesting observations of the same careful observer
upon the architectural habits of Melicerta would seem to
throw a doubt upon the propriety of ascribing to the organ in
question any sensorial function.

But however remarkable it may seem that an animal should
build its house with its nose, we must remember that a
similar combination of functions is obvious enough in the
elephant.

No eyespots exist in the adult Lacinularia. In the young
there are two red spots on the upper surface of the trochal disc,
which are stated by Professor Ehrenberg to be seated upon
“ medullary masses”? (Mark-Knétchen). I could not satisfy
myself either of the truth of this statement or the contrary,
in consequence of the difficulty of distinguishing the separate’
tissues in the young animal.

I may be permitted here to say a word upon the nature of
the “ calcar” or “ respiratory tube” of Ehrenberg, which
exists in so many Rotifera. For his first notion, that it is
connected with the reproductive system, Professor Ehrenberg
has substituted the idea that it 1s a respiratory tube, through
which currents of water are conducted into the cavity of the
body, and bathe the “trembling organs” which he calls

10 Houxtey on Lacinularia socialis.

“gills.” Professor Ehrenberg, however, has not produced
any evidence of such in-going currents, and Dujardin has
denied their existence. So far as has yet been observed,
the calcar is in immediate connection with the nervous
ganglion. Melicerta affords a very good opportunity for ex-
amining the structure of the organs, of which in this genus
there are two. It is a somewhat conical process of the in-
tegument, containing a similar process of the internal mem-
brane. This, however, stops short a little distance from the
extremity, and forms a transverse diaphragm, from the centre
of which a bunch of long and excessively delicate sete pro-
ceeds (fig.29). I could observe no trace of any aperture with
a power of 600 diam., though of course this is merely negative
evidence.

Is it not possible that, as the “ ciliated sac” of the Asci-
dians has its analogue in the “ fossa” of the Rotifera, so the
calcar may answer to the “ languet,’ which has a similar
relation to both sac and ganglion ?

In Notommata there is no calcar, but nervous cords proceed
from the ganglion to the ciliated spots about the middle of
the dorsal surface (Dalrymple).

Reproductive Organs.—Considering Professor Ehrenberg’s
determination of the male organs to be set aside, his descrip-
tion of the reproductive organs extends only to the ovary,
which, he says, in Lacinularia “ lies in the posterior cavity
of the body, and has thus one and the same outlet with the
intestine ” (p. 403). This seems to imply an oviduct; I
could, however, see no such organ.* ‘l’he ovary consists of
a pale, slightly granular mass ofa transversely elongated form
(fig. 5 7), and somewhat bent round the intestine; it is
enclosed within a delicate transparent membrane, which is
hardly visible in the unaltered state, but becomes very obvious
by the action of acetic acid, which contracts the substance of
the ovary and throws the membrane into sharp folds.

Pale clear spaces, which sometimes seem to be limited by
a distinct membrane, are scattered through the substance of
the ovary, and in each of these a pale circular nucleus is
contained. ‘The nucleus is more or less opaque, but usually
contains 1-3 clear spots (fig. 9).

These are the germinal vesicles and spots of the future
ova. Acetic acid, in contracting the pale substance, groups
it round these vesicles, without, however, breaking it up into
separate masses. It renders the nuclei more evident.

* Leydig (1. ¢., p. 469) says that there is a wide oviduct which becomes
folded when empty. I must leave the discrepancy until a further exami-
nation decides which is right.

Huxzey on Lacinularia socials. a =

The ova are developed thus:—One of the vesicles in-
creases in size, and reddish elementary granules appear in
the homogeneous substance round it (fig. 10). This accumu-
lation increases until the ovum stands out from the surface
of the ovary ; but invested by its membrane which, as the
ovum becomes pinched off as it were, takes the place of a
vitellary membrane.

In the mean while the germinal vesicle has increased in
size, and its nucleus is no longer visible. In the ovum it
appears as a clear space ; isolated by crushing the ovum it is
a transparent, colourless vesicle.

The perfect ova are oval, about 1-10th inch in diameter,
and are extruded by the parent into the gelatinous connect-
ing substance, where they undergo their development (fig. 11).

The changes which take place after extrusion, or even to
some extent within the parent, are—1, the disappearance of
the germinal vesicle (as I judge from one or two ova in
which I could find none); 2, the total division of the yolk,
as described by Kolliker in Megalotrocha, until the embryo
is a mere mass of cells, from which the various organs of the
foetus are developed (figs. 12, 13, 14, 15, 16).

The youngest fetuses are about 1-70th of an inch in length.
The head is abruptly truncated, and separated by a con-
striction from the body: a sudden narrowing separates the
other extremity of the body from the peduncle, which is ex-
ceedingly short and provided with a ciliated cavity, a sort of
sucker, at its extremity. The head is nearly circular, seen
from above, and presents a central protuberance in which
the two eyespots are situated. The margins of this pro-
tuberance are provided with long cilia—it will become the
upper circlet of cilia in the adult.

The margin of the head projects beyond this, and is fringed
with a circlet of shorter cilia; this is the rudiment of the
lower circlet of cilia in the adult. The internal organs are
perceived with difficulty ; but the three divisions of the ali-
mentary canal, which is as yet straight and terminates in a
transparent cloaca, may be readily made out. ‘The water-
vascular canals cannot be seen, but their presence is indicated
by the movement of their contained cilia here and there
(fig. 17).

In young Lacinularie, 1-380th of an inch in length, the head
has become triangular, the peduncle is much elongated, and
thus it gradually takes on the perfect form (fig. 18). The
young had previously crept about in the gelatinous investment
of the parents ; they now begin to “swarm,” uniting together
by their caudal extremities, and are readily pressed out as

12 Hoxtery on Lacinularia socialis.

united free swimming colonies, resembling, in this state, the
genus Conochilus.

The process of development of these ova is therefore exactly
that which takes place in all fecundated ova, and would lead
one to suspect that spermatozoa should be found somewhere
or other.

Now, from the observations of Mr. Dalrymple, we should
be led to seek a distinct male form with the ordinary sperma-
tozoa. From those of Kélliker, on the other hand, we should
equally expect to find each individual a hermaphrodite, with
the very peculiar spermatozoon-like bodies which he has de-
scribed in Megalotrocha.

I must have examined some scores of individuals of Lacinu-
laria with reference to the former case, without ever finding
a trace of a male individual. All were similar, all contained
either ova or ovarlum, nowhere was an ordinary spermatozoon
to be seen. On the other hand, I found in many individuals
singular bodies, which answered precisely to Kélliker’s descrip-
tion of the ‘‘ spermatozoa” of Megalotrocha. ‘They hada pyri-
form head about 1-1000th in. in diam, (fig. 19), by which
they were attached to the parietes of the body, and an append-
age four times as long, which underwent the most extraordi-
nary contortions, resembling however a vibrating membrane
much more than the tail of a spermatozoon; as the undulating
motion appeared to take place in only one side of the append-
age, which was zigzagged, while the other remained smooth.

According to Kélliker again, these bodies are found only in
those animals which possess ova undergoing the process of yolk
division, while I found them as frequently in those young forms
which had not yet developed ova, but only possessed an ovary.

Are these bodies spermatozoa ?* Against this view we have

* Leydig (loc. cit., p. 474) has observed, in several cases, what I de-
scribe as probable spermatozoa, but considers them to be parasites.

He does not notice the similarity of these bodies to those described by
Kolliker in Megalotrocha ; but thinks that the l-tter has been misled by
the vibratile organs.

Leydig does not appear to be acquainted with the important observa-
tions of Dalrymple, Brightwick, and Gosse; but brings forward as the
true spermatozoon a tertium quid, whose description I subjoin in his own
words :—‘‘ In almost every colony we meet with from one to four (in large
colonies) individuals which are distinguishable from the rest at the first
glance. By reflected light they appear quite white, which appearance
arises from peculiar corpuscles which fill the cavity of the body more or
less completely, and are driven hither and thither by the contractions of
the animal, as well into the wheel-organ as into the caudal appendage.
They are yellowish globular bodies, with sharp contours, 1-5000th to
1-1700th of an inch in diameter, with a double centre and a lighter peri-
phery. The surface is covered by a mesh-work of bands projecting in-

~*

Houx.ey on Lacinularia socialis. 13

the unquestionable separation of the sexes in Notommata,
and the very great difference between these and the spermato-
zoa of Notommata. Neither are the mode of development nor
the changes undergone by the ovum any certain test that it
requires or has suffered fecundation, inasmuch as the process
closely resembles the original development of the aphides (see
Leydig, Siebold and Kélliker, Zeitschrift, 1850).

In the view that Kélliker’s bodies are true spermatozoa, it
might be said—1. That the sexes are united in most Disto-
mata, for instance, and separated in species closely allied (e.g.
D. Ohenii).

2. That the differences between these bodies and the sperma-
tozoa of Notommata is not greater than the difference between
those of Triton and those of Rana.

3. That their development from nucleated cells within the
body of Megalotrocha (teste Kolliker) is strong evidence as to
their having some function to perform; and it is difficult to
imagine what that can be if it be not that of spermatozoa. How-
ever, it seems to me impossible to come to any definite con-
clusion upon the subject at present.*

Kolliker supposes that Ehrenberg has seen the ‘ spermato-
zoa’’ and has taken them for the ‘ long vibratile bodies ;’’ while
Siebold imagines that Kolliker has taken the long vibrating bodies
for spermatozoa. No one, however, who has seen both struc-
tures can be in any danger of confounding the one with the other.

Asexual propagation of Lacinularia.—W hatever may be the
nature of the process of reproduction just described, there exists
another among the Rotifera, which has been noticed by almost
every one, but not hitherto distinguished or understood. This
is the production of the so-called “ winter ova,’ but which from
their analogy with what occurs in Daphnia, I prefer to call
*‘ ephippial ova.”

Ehrenberg says that many ova of Hydatina have a double
shell, and between the two shells there is a wide space.
‘¢ Similar ones occur in many Rotifera, in various often irre-
gular forms: these have a much slower development, and [ call
them thence winter ova” (p. 413). See also his account of
Brachionus urceolaris (p.512). He does not notice the occur-
rence of these ova in Lacinularia or Megalotrocha.

ternally, which give the body a mosaic (parquettirtes) appearance. Im-
moveable hairs, 1-1700th of an inch long, may be seen in isolated globules
to radiate from the surface.”

I have not observed any of these bodies.

* T may mention here that I have found in Melicerta an oval sac lying
below the ovary, and containing a number of strongly-refracting particles
ey resembling in size and form the heads of the spermatozoa of Laci-
nularia.

14 Houxtey on Lacinularia socials.

Kélliker speaks of the ova of Megalotrocha acquiring a deep
yellow investment, as if it were a further development of those
ova whose yolk he saw divided. I am strongly inclined to be-
lieve, however, that he was misled by the peculiar appearance
of the winter ova, which look as if they had undergone yolk
division. -

Dalrymple gives a lengthened account of these peculiar ova
in Motommata. He says that they are dark, and that their outer
covering appears to consist of an aggregation of cells, under
which is a second layer of cells containing pigment molecules.
No distinct germinal vesicle, he says, is to be found in these
ova ‘‘ from the want of general transparency ” (loc. cit., p.340).

It will be observed that all these authors consider the winter
ova or ephippial ova and the ordinary ova to be essentially ¢den-
tical, only that the former have an outer case. The truth is,
that they are essentially different structures, The true ova are
single cells which have undergone a special development. The
ephippial ova are aggregations of cells (in fact, larger or smaller
portions—sometimes the whole—of the ovary), which become
enveloped in a shell and simulate true ova.

In a fully grown Lacinularia which has produced ova, the
ovary, or a large portion of it, begins to assume a blackish tint
(fig. 20) ; the cells with their nuclei undergo no change, but
a deposit of strongly refracting elementary granules takes place
in the pale connecting substance. Every transition may be
traced from deep black portions to unaltered spots of the
ovarium, and pressure always renders the cells with their nuclei
visible among the granules. The investing membrane of the
ovary becomes separated from the dark mass so as to leave a
space, and the outer surface of the mass invests itself with a
thick reddish membrane (fig. 21), which is tough, elastic, and
reticulated from the presence of many minute apertures. This
membrane is soluble in both hot nitric acid and caustic potass.*

The nuclei and cells, or rather the clear spaces indicating them,
are still visible upon pressure, and may be readily seen by
bursting the outer coat.

By degrees the ephippial ovum becomes lighter, until at last
its colour is reddish brown, like that of the ordinary ova; but
its contents are now seen to be divided into two masses—hemi-
spherical from mutual contact (fig. 22). If this body be now
crushed, it will be found that an inner structureless membrane
exists within the fenestrated membrane, and sends a partition

* Leydig (I. c., p. 453) says that the shells of the ova were not dis-
solved by maceration in a solution of caustic soda (cold?) for twenty-four
hours, and thence concludes that they may be composed of chitin.

The above observation tends to the contrary conclusion.

Huxuey on Lacinularia socials. 15

inwards, at the line of demarcation of the two masses (fig. 23).
The contents are precisely the same as before, viz., nuclei and
elementary granules (fig. 24). This, indeed, may be seen
through the shell without crushing the case.

I was unable to trace the development of these ephippial
ova any further. Those of MNotommata, it appears, lasted for *
some months without change (Dalrymple).

It is remarkable that in Lacinularia these bodies eventually,
like the ephippium of Daphnia, contain two ovum-like
masses ; and there can, I think, be little doubt that the former,
like the latter, are subservient to reproduction.

There are then two kinds of reproductive bodies in Lacinu-
laria :—

1. Bodies which resemble true ova in their origin and
subsequent development, and which possess only a single
vitellary membrane.

2. Bodies, half as large again as the foregoing, which re-
semble the ephippium of Daphnia; like it have altogether
three investments; and which do not resemble true ova either
in their origin or subsequent development ; which therefore
probably do not require fecundation, and are thence to be
considered as a mode of asexual reproduction.*

General Relations of the Rotifera.—It is one of the great
blessings and rewards of the study of nature that a minute and
laborious investigation of any one form tends to throw a light
upon the structure of whole classes of beings. It supplies us
with a fulcrum whence the whole zoological universe may be
moved. I would illustrate this truth by showing how, in my
belief, the structure of Lacinularia, as thus set forth, taken in
conjunction with some other facts, gives us a clue to the solu-
tion of the questio vexata of the zoological position of the
Rotifera, and thence to the serial affinities of a large portion of
the Invertebrata.

* Leydig distinguishes particularly between the ordinary, and what I
have termed, the ephippial ova.

His description of the latter agrees essentially with that which has been
given above; but he has not, I think, observed the genesis of the ephippial
ova with sufficient care, and he thence interprets their structure by sup-
posing that they are ordinarily fecundated ova, which have undergone
a peculiar method of cleavage. The tendency of the observations de-
tailed above, on the other hand, is to show that they are not ova at all in
the proper sense, but peculiar buds like those of Aphis or Gyrodactylus,
and as such are capable of development without fecundation.

In the new edition of Pritchard’s ‘ Infusoria,’ it is stated (p. 620), that
“‘in a recent paper by Mr. Howard on this species, he states that there
are two kinds of reproductive bodies—one the ordinary ova, the other twice
their size, representing gemmz.” No reference is given to Mr. Howard’s
paper, and I have been at a loss to discover it, though desirous to do justice
to him if possible.

i Hextey on Lacinularia socialis.

The curious analogy in form between the genus Stepha-
noceros and the Polyzoa has, I believe, been the chief considera-
tion which has led many naturalists, both in England and on
the Continent, to arrange the Polyzoa and Rotifera together.
This has been done in two ways, either by denying the affinity
of the Rotifera with the Vermes, and so approximating them
to the Polyzoa considered as organized on the molluscous type,
or, as Leuckhart has done, by admitting the affinity of the
Rotifera with the Vermes, but denying that of the Polyzoa
with the Mollusca.

I believe that there is a fundamental error in each case,
namely, that of approximating the Polyzoa and the Rotifera
at all. The resemblance between Sfephanoceros and a Poly-
zoon is very superficial. No Polyzoon has the cilia on its
tentacles arranged like those of Stephanoceros ; nor has any a
similarly-armed gizzard: still less is there any trace of the
water-vascular system which exists in all Rotifera.

The relations between the Polyzoa and the Rotifera, then,
are at the best mere analogies.

On the other hand, the general agreement in structure be-
tween the Rotifera and the Annuloida— under which term I
include the Annelida, the Echinoderms, Trematoda, ‘lur-
bellaria, and Nematoidea—is very striking, and such as to
constitute an unquestionable affinity.*

The terms of resemblance are these :—

1. Bands of cilia, resembling and performing the functions
of the wheel-organs, are found in Annelid, Echinoderm, and
Trematode larve. |

2. A water-vascular system, essentially similar to that of the
Rotifera, is found in Monececious Annelids, in Trematoda, in
Turbellaria, in Echinoderms, and perhaps in the Nema-
toidea.}

3. A similar condition of the nervous system is found in
Turbellaria.

4. A somewhat similarly armed gizzard is found in the
Nemertidz ; and the pharyngeal armature of a Nereid larva
may well be compared with that of Albertia.

5. The intestine undergoes corresponding flexures in the
Echinoderm larve. There are, therefore, no points of their
organization in which the Rotifera differ from the Annuloida ;

* M. Milne Edwards, with his accustomed acuteness, pointed out
(Annales des Sciences, 1845) the close affinity of the Rotifera with the
Annelids, the Turbellaria, and the Nematoidea; but he did not include
the Echinoderms in the group, doubtless because, at the time he wrote,
sufficient was not known of the Echinoderm larve to demonstrate their
truly annuloid nature.

+ To these may be added the Cestoidea and the Nemertide.

Huxtey on Lacinularia socialis. 17

and there is one very characteristic circumstance, the presence
of the water-vascular system, in which they agree with them.

Now, with what Annuloida are the Rotifera most closely
allied? To determine this point, we must ascertain what is
the fundamental type of organization of the Rotifera.

_ Suppose in Lacinularia a line to be drawn from the mouth °
to the anus, and that this be considered as the axis of the body ;
suppose, again, that the side on which the ganglion lies is the
dorsal side, the opposite being the ventral ; suppose, also, the
mouth end to be anterior, the anal end posterior,—then it will
be found that the lower circlet of cilia upon the trochal disc
encircles the axis of the body, while the upper circlet of large
cilia does not encircle the axis, but lies in the lower and an-
terior region of the body.

If the region behind that ciliary circlet which is traversed by
the axis be called the post-trochal region, and that in front of
it the pre-trochal region, we find that the circlet of large cilia
is developed in the inferior pre-trochal region.

Now compare this Rotifer with the larva of an Annelid.
It will be immediately seen that the two are of essentially
the same type, only that, while the Annelid larva is equally
and symmetrically developed in all its regions, and has
_ frequently no accessory ciliated bands, the Rotifer has its
superior post-trochal and inferior pre-trochal regions de-
veloped in excess ; so that the anus is thrown to the ventral,
while the mouth is thrust towards the dorsal surface,* an
accessory ciliated circlet being at the same time developed in
the latter region.

Meliceria ringens (compare figs. 26-28) resembles Lacinu-
laria in the arrangement of its ciliated bands, only they are
far more distorted from their normal circular form. Tubi-
colaria closely resembles Melicerta, and there can be little
doubt that Megalotrocha and Limnias are to be added to this
division.

In Brachionus, Philodina, Rotifer, Notommata, the same
fundamental type obtains, but the deviation from symmetry
takes place in a different way.

In all these it is the ventral post-trochal region which is
over-developed, and therefore the anus is thrown to the dorsal
or ganglionic side.

In Notommata the trocha appears to be simple and un-
altered in most species, and there is no accessory circlet.

* This over-development is not a mere matter of hypothesis. The
young Lacinularia has the anus nearly terminal, and the “‘ peduncle” only
subsequently attains its full proportions. Compare fig. 17 and fig. 18,
pL.

VOL. I. Cc

18 Hoxtey on Lacinularia socialis.

In NV. aurita, however, as it appears from Mr. Gosse’s de-
scription, and in Brachionus polyacanthus (figs. 30-33), several
processes, three in the latter case, are developed from the
superior pre-trochal region. They are richly ciliated, and
appear to represent the accessory circlet of Lacinularia.

Another distinct type is presented by Philodina (figs. 34-
37). In this the great trocha is bent upon itself, and the
anterior divison of it, at first sight, simulates an accessory
circlet developed in the superior pre-trochal region. It is not
so, however, as the continuity of the band of cilia can be
readily traced throughout.

To this division of the Rotifera, viz. those which have the
anus on the same side of the body as the ganglion, appear to
belong the genera Stephanoceros and Floscularia—at least,
if the ganglion be what I believe it to be, a granular mass,
in connexion with the upper part of a large oval mass com-
posed of clear cells, and having a pit in its centre exteriorly,
which I believe to be the altered ciliated sac.

These might then be considered as Notommate whose
trochal circlet had become produced into long processes in
Stephanoceros, while they remain as shorter knobs in Filos-
cularia ; a tendency to which development may be traced in
the little processes into which the trochal circlet is thrown
around the mouths of Lacinularia and Melicerta, and perhaps
in the three processes which, according to Mr. Dalrymple,
arch over the mouth in Notommata.

But Stephanoceros, Philodina, Notommata, Brachionus, and
Lacinularia are the types of the great divisions of the Rotifera,
and whatever is true of them will probably be found to be
true of all the Rotifera.

We may say, therefore, that the Rotifera are organized upon
the plan of an Annelid larva, which loses its original symmetry
by the unequal development of various regions, and especially
by that of the principal ciliated circlet or trochal band; and it
is curious to remark that, so far as the sexes of the Rotifera can
be considered to be made out (approximatively), the dicecious
forms belong to the latter of the two modifications of the type
which have been described, while the moneecious forms belong
to the former. |

It is this circumstance which seems to me to throw so clear
a light upon the position of the Rotifera in the animal series.
In a Report in which I have endeavoured to harmonise the
researches of Prof. Miller upon the Echinoderms,* I have
shown that the same proposition holds good of the latter in

* Annals of Natural History, 1851.

Huxtry on Lacinularia socials. 19

their larval state, and hence I do not hesitate to draw the con-
clusion (which at first sounds somewhat startling) that the
Rotifera are the permanent forms of Echinoderm larve, and
hold the same relation to the Echinoderms that the Hydriform
Polypi hold to the Medusz, or that Appendicularia holds to.
the Ascidians.

The larva of Sipunculus might be taken for one of the
Rotifera; that of Ophiura is essentially similar to Stephano-
ceros; that of Astertas resembles Lacinularia or Melicerta.
The pre-trochal processes of the Asterid larva Brachiolaria are
equivalent to those of Brachionus.

Again, the larve of some Asterid forms and of Comatula
are as much articulated as any Rotifera.

It must, I think, have struck all who have studied the Echi-
noderms, that while their higher forms, such as Echiurus and
Sipunculus, tend clearly towards the Dicecious Annelida, the
lower extremity of the series seemed to lead no-whither.

Now, if the view I have propounded be correct, the Rotifera
furnish this wanting link, and connect the Echinoderms with
the Nemertidz and Nematoid worms.

At the same time it helps to justify that breaking up of the
class Radiata of Cuvier, which I have ventured to propose
elsewhere, by showing that the Rotifera are not ‘ radiate”
animals, but present a modification of the Annulose type—
belong, in fact, to what I have called the Annuloida, and
form the lowest step of the Echinoderm division of that sub-
kingdom.

From our imperfect knowledge of the Nematoid worms it
is difficult to form a definite scheme of the affinities of the
Annuloida; but perhaps they may be sketched as in the
Diagrams, pl. III. |

These diagrams represent the arrangement of the ciliated
bands with relation to the axis of the body in the Rotifera.

Underneath each Rotifer is an Annelid or Echinoderm larva,
with its ciliary bands represented in a like diagrammatic
manner, to show the essential correspondence between the two.

This paper is now printed exactly as it was read before the Micro-
scopical Society on the 81st of December, 1851, with the exception of
those notes which refer to the very excellent memoir of Dr. Leydig, pub-
lished in February, 1852. Dr. Leydig must have been working at the
subject at about the same time as myself, in the autumn of last year ;
and if I refer to the respective dates of our communications, it is merely
for the purpose of giving the weight of independent observation to those
points (and they are the most important) in which we agree. —

It is the more necessary to draw attention to this fact, since Professor
Ehrenberg, in a late communication to the Berlin Academy, hints that
the younger observers of the day are in a state of permanent conspiracy
against his views. fy ic he

July 9, 1852.

e2

(1 BD i)

On the Structure of the Rarnmes of Cactus ENNEAGONUs. By
Joun Quexett, Esq., Professor of Histology to the Royal
College of Surgeons of England. (Read Jan. 28, 1852.)

Every living being that is made up of parts or organs, each
having a definite structure, and performing a certain office, is
termed an organized being; and the materials, however com-
plicated, of which it is composed, are termed organic matter.

The components of the Mineral Kingdom, on the contrary,
possessing little or no structure, but generally being homoge-
neous throughout, and having no adaptation of parts to per-
form separate functions, are called inorganic or inorganized.

If organic matter be subjected to chemical analysis, it will
be found that in the first stage certain compounds, termed by
some chemists proximate principles, or organic compounds or
organizable substances by others, will be obtained; each of
which principles, by further or ultimate analysis, will yield
simple elements. ‘Thus, for instance, from the organized sub-_
stance termed muscle we obtain by analysis, first, fibrine, a
proximate principle, which is its chief constituent; and, sub-
sequently, by the analysis of fibrine, we get the principal
elements—oxygen, hydrogen, carbon, nitrogen, and sulphur
in certain proportions. If, however, a mineral, or inorganic
matter of any kind be subjected to analysis, we get no proxi-
mate principles, but only simple elements. Organic matter
may be found in two states, viz., in that of life or in that of
death. Living matter possesses the powers of growth and
integrity, may select from surrounding materials, and appro-
priate to its uses the inorganic elements; but in the state of
death these powers are destroyed, and decay is the natural
consequence.

It is to the nature of this organic basis or matter of plants
that I would now direct your attention, leaving that of animals
for future consideration.

In commencing our examination with the vegetable king-
dom we shall find that inorganic or earthy matter exists in
plants in two states, viz., Ist, as crystals, termed raphides,
occurring in the interior of cells, and 2nd, in intimate con-
nexion with the organic basis of the plant—ain this last state
the inorganic element chiefly consists of silica.

If we examine a portion of the layers of an onion or of a
squill, or by taking a thin section of the stem or root of the
garden rhubarb, we shall observe many cells in which either
bundles of needle-shaped crystals or masses of a stellate form
occur; these are termed raphides, from the Greek Pagis, a
needle, the first crystals discovered being of this shape.

Quexert on the Raphides of Cactus enneayonus. 21

Raphides were first noticed in Malpighi in Opuntia, and
were subsequently described by Jurine and Raspail.

According to the latter observer the needle-shaped or aci-
cular are composed of phesphate, and the stellate of oxalate
of lime. There are others having lime as a basis, combined
with tartaric, malic, or citric acid. These are easily de-
stroyed by acetic acid; they are also very soluble in many of
the fluids employed in the conservation of objects: some of
them are as large as the 1-40th of an inch; others are as small
as the 1-1000th. They occur in all parts of the plant—in the
stem, bark, leaves, stipules, sepals, petals, fruit, root, and even
in the pollen, with few exceptions. They are always situated
in the interior of cells, and not, as has been stated by Raspail
and others, in the intercellular passages.*

Some of the containing cells become much elongated, but
still the cell-wall can be readily traced. In some species of
Aloe, as for instance Aloe verrucosa, with the naked eye you
will be able to discern small silky filaments. When these
are magnified they are found to be bundles of the acicular form
of raphides. In portions of the cuticle of the medicinal
squill— Scilla maritima—several large cells may be observed,
full of bundles of needle-shaped crystals. These cells, how-
ever, do not lie in the same plane as the smaller ones belong-
ing to the cuticle. In the cuticle of an onion every cell is
occupied either by an octohedral or a prismatic crystal of
oxalate of lime—in some specimens the octohedral form pre-
dominates, but in others from the same plant, the crystals may
be principally prismatic, and are arranged as if they were be-
ginning to assume a stellate form.

Those persons who are in the habit of examining urinary
deposits must be familiar with the appearance of the crystals
of oxalate of lime, and would readily recognise their close
resemblance to those in the cells of the onion.

Raphides of oxalate of lime are found in very great abund-
ance in the medicinal rhubarb—the best specimens from
Turkey containing as much as 35 per cent.; those from the
East Indies 25 ; and the English, or that sold in the streets
by men dressed up as Turks, 10 per cent.

Buyers of this drug generally judge of its quality by its
grittiness, that is by the quantity of raphides it contains ; and
this is a curious fact, as the crystalline matter cannot be of
any beneficial importance in the action of the medicine, for the

* As as exception I may state that, many years ago, I discovered them
in the interior of the spiral vessels in the stem of the grape-vine; but
with some botanists this would not be considered as an exceptional case,
the vessels being regarded as elongated cells.

22 Quexerr on the Raphides of Cactus enneagonus:

tincture in which no raphides are contained is as efficacious
as the powder.

Some plants, as many of the cactus tribe; are made up
almost entirely of raphides. In some instances every cell of the
cuticle contains a stellate mass of crystals, in others the whole
intericr is full of them, rendering the plant so exceedingly
brittle that the least touch will occasion a fracture, so much so
that some specimens of cactus senilis, said to be 1000 years
old, which were sent a few years since to Kew from South
America, were obliged to be packed in cotton, with all the
care of the most delicate jewellery to preserve them during the
transport,

Raphides of peculiar figure are common in the bark of
many trees. In the hiccory (Carya alba) may be observed
masses of flattened prisms having both extremities pointed.
Similar crystals are present in the bark of the lime-tree; they
occur in rows, their pointed extremities nearly touching each
other, their principal situation being in the cellular tissue close
to the medullary rays. Other forms of crystals, as the rhom-
bohedron and a small stellate form, are also found in the bark
of the lime.

In vertical sections of the stem of Eleagnus angustifolia nu-
merous raphides of large size may be seen in the pith.

Raphides are also found in the bark of the apple-tree, and
in the testa of the seeds of the elm; each cell contains two or
more very minute crystals.

It is at present not known what office raphides perform in
the economy of the plant: some have gone so far as to state
that they are deposits to be applied towards the mineral part
or skeleton of the plant; but the fact of their being insoluble
in vegetable acids would prove this view of their use to be
erroneous. The more rational supposition is, that they are
generally accidental deposits formed by the union of vege-
table acids with lime or other base existing in the plant or
taken up from the soil. They may, however, be formed
artificially, and my late brother succeeded in doing so in the
following manner :—If oxalic or phosphoric acid be added to
lime-water, the precipitate will be pulverulent and opaque.
If, however, a vessel containing oxalate of ammonia in solution
be connected by means of a few filaments of cotton with
another vessel containing lime-water, crystals will be formed
at the end of the fibres in contact with the lime-water.

This led him to attempt to form them in the interior of
cells: he selected for the purpose a portion of rice paper ;
this substance was placed in lime-water under an alr-pump in
order in fill the cells with the fluid ; the paper was then dried,

QueKeEtTT on the Raphides of Cactus enneagonus. 23

and the process again and again repeated, until many of the
cells were charged with lime-water; portions of the paper
were then placed in weak solutions both of oxalic and phos-
phoric acid, and at the end of three days crystals were found
in the cells in both instances, those of the oxalic acid being of _
the stellate and those in the phosphoric acid being of the
rhombohedral form. None of the acicular, however, were
ever present, although the process was continued for ten days.
One of these pieces of rice paper I now show you, and a
stellate mass of crystals is very plainly to be seen in the centre
of the field—each precisely resembles the raphides found in
rhubarb.

The above description, which is a modification of that given
in my lectures, well applies to the raphides in most plants,
but the case will appear to be a little different in those plants,
such as the cacti, which live to a great age, and in which the
crystalline matter is in the greatest abundance. Whilst
working at this subject about twelve months since I was in-
duced to examine the raphides of a species of Cactus termed
enneagonus, a specimen of which had been given me by a
friend as abounding in crystals. This specimen I have with me,
just as I received it, the part containing the crystals being about
thirty-nine years old; that they are very numerous, and at the
same time very large, may be known by their being visible to
the naked eye. If any of these raphides be examined in fluid
with a power of at least 100 diameters, they will appear to be
made up of crystals (as far as their external surface is con-
cerned), which project outwards in the form both of sharp
pointed and truncated prisms; and if the centre be brought
into focus this part will be found more opaque than the rest,
and to be of a circular figure like a nucleus. If the masses be
mounted in Canada balsam before they are examined they
will then present one or other of the appearances given in
Plate III. figs. 1, 2, 3,4; some, as in fig. 1, will show a nucleus
surrounded by concentric lamine of a brown colour ; others, as
in fig. 2, will exhibit a spot like a nucleus, first surrounded by
concentric lamine, but towards the margin the laminze become
irregular, and the margin itself is composed of prismatic
flattened crystals, not clear and transparent, but more or less
granular, whilst some other specimens, as shown in figs. 3 and
4, are made up almost entirely of the prismatic crystals, with
little or no trace of concentric lamination. Having found this
to be the case I was anxious to ascertain the chemical com-
position of these so-called raphides, and for the purpose I
tried the action of various re-agents upon them, and noticed
that the crystals were slowly dissolved in dilute hydro-chloric

24 QuvexeErr on the Raphides of Cactus enneagonus.

acid, but I was much astonished to find that in many cases a
basis or cast of the entire mass was left behind after the action
of the acid had ceased ; and in most instances I could tell pre-
cisely not only the spot where the crystals had been, but also
form some general idea of the shape of the mass, and instead
of their being, as I first imagined, a mass of crystals only,
{ found that there was some organic matter or basis connected
with them. |

When one of these raphides is crushed between two plates
of glass, the outer crystals are readily detached ; some of these
are represented by fig. 6: the part composing the nucleus is
much the hardest, and exhibits a radiated and concentric
laminated deposit, like the masses of carbonate of lime found
in the urine of the horse. If portions of the cellular tissue of
the cactus be examined, some cells will occasionally be found
in which a more or less spherical mass, as shown in fig. 5,
occurs in the centre of each: these masses correspond in every
respect with the nuclei of the larger raphides: it would there-
fore appear that in the early stages of development of these
raphides the nucleus consisted of one of these spherical bodies,
and the crystals on the exterior were formed subsequently. It
may also happen that the bases of some of the crystals in
process of time coalesce to form laminz, a condition not
unlike that occurring in shell, as has been so well described by
Dr. Carpenter, or rather like that which takes place in the
formation of most of the laminated kinds of urinary calculi.

My object in bringing the subject before the Society at this
time is to ask those of our members who are chemists, and
would be willing to look into the matter, if they could deter-
mine the nature of the residuum or basis left after the destruc-
tion of the earthy ingredient by means of the acid. They will
find, as I shall presently have the opportunity of showing you,
that there is something peculiar in the dissolution of the
crystals—they are all, more or less, granular, as if the organic
matter were not confined to the investing membrane, but int1-
mately mixed up or incorporated with every atom of the lime.
I have this day examined some sections of the Soap wood of
China, in which stellate masses of crystals are very abundant.
If these be acted on by dilute hydrochloric acid, the earthy
constituent will disappear, but a cast of the original mass will
be preserved in what may be termed organic matter. This
point, however, is the one which requires to be carefully ex-
amined by persons more skilled than myself in the science of
organic chemistry.

As far as my observations have hitherto gone, it would
appear to be a rule that we rarely, if ever, find inorganic

Quexetr on the Raphides of Cactus enneagonus. 25

material in the vegetable or animal kingdom, except in the
crystalline state, without the existence of an organic basis.

Since the above was written, my friend Dr. Lionel Beale
has been kind enough to examine the raphides in question, .
and the following is his report on the subject.

“ A few of the white globular crystalline masses were
treated with boiling distilled water, and the aqueous solution,
after being filtered, was evaporated to a small bulk. Upon
examining the residue by the microscope, numerous small
colourless crystals, in the form of obtuse rhomboids, were
observed. The residual solution was found to give precipi-
tates insoluble in strong nitric acid, with solutions of nitrate
of barytes and nitrate of silver, proving the presence of
chlorine and sulphuric acid. Oxalate of ammonia gave a pre-
cipitate insoluble in acetic acid, but soluble in strong nitric
acid, showing the presence of lime.

“* Hence boiling distilled water extracted a small quantity
of soluble matter, which contained lime, chlorine, and sul-
phuric acid, probably in the form of sulphate of lime and
chloride of sodium.

“« Acetic Acid.—The crystalline masses were not affected by
boiling acetic acid.

“‘ Potash.—No observable action was produced by boiling a
few of the masses in solution of caustic potash.

“ Nitric Acid—Upon the addition of strong nitric acid,
effervescence occurred with some few of the bodies as they
dissolved, but upon the majority this re-agent exerted little
action in the cold. When the mixture was boiled, complete
solution immediately took place.

“The acid solution was evaporated to dryness; the dry
residue was boiled in distilled water, and the filtered solution,
after concentration, was allowed to remain in a still place for
some time. Upon examining the residue with the microscope
numerous well-formed octohedra of oxalate of lime were ob-
served.

“¢ Another portion of the original matter was incinerated :—
the masses still retained their globular form, but became black,
and the products of combustion burnt with a blue lambent
flame. After exposure to a dull red heat for three or four
hours, the crystals were perfectly decarbonized, and by the
unaided eye could scarcely be distinguished from those which
had not been incinerated. Upon microscopical examination,
however, the crystalline fragments of which the crystalline
masses were composed, were found to have acquired a dark
granular uneven surface, and the sharpness of outline had been

26 QueEKETT on the Raphides of Cactus enneagonus.

destroyed. The decarbonized residue was entirely dissolved
in acetic acid with brisk effervescence ; and upon the addition
of a solution of oxalate of ammonia to the acid solution, an
abundant white precipitate was immediately produced; this
was soluble in strong nitric acid, but insoluble in excess of
acetic acld—oxa/ate of lime. In all probability, therefore, the
crystalline masses consisted of—

“ 1, A little organic matter ;

“2. Sulphate of lime ;

“ 3. A little of carbonate of lime ;

‘* 4. Traces of chloride of sodium ;

“* 5. A vegetable salt of lime, containing a considerable pro-
portion, or consisting entirely of oxalate of lime.”

On the occurrence of a Membranous Cell or Cyst upon the
Olfactory Nerve of a Horse, containing a large Crystal of
Oxalate of Lime. By James B. Simonps, Esq. (Read
April 28, 1852.) |

Tue recent publication of Mr. Quekett’s lectures on the occur-
rence of earthy salts in both animal and vegetable cells gives
an unusual interest to these depositions, and more especially
when they are met with in those parts of the organism of
animals where we should scarcely anticipate their presence.
For this reason, and as an addendum to his valuable papers
now being read before the Society, I am induced to bring
before you an interesting and novel fact which has lately
come to my knowledge relating to a deposit of the oxalate of
lime within a cell or small membranous cyst. :

In the latter part of March a pupil of the Royal Veterinary
College found, in dissecting the brain of a horse which had
been procured from the slaughterhouse, a small transparent
cyst, possessing a very bright or glistening aspect, attached to
the bulbous portion of the right olfactory nerve. ‘The speci-
men, together with a small portion of the nerve, was carefully
removed, and a day or two afterwards it was kindly presented
to me, he at that time believing it to be an hydatid.

From having been kept in water I found that the nerve was
somewhat decomposed, and very readily separated into a pulpy
mass ; a circumstance which prevented any minute examina-
tion of its structure being made. I observed, however, that its
substance was partly absorbed, so as to form a cup-like con-
cavity for the lodgment of the cyst; and I am led to infer
from this circumstance that the sense of smell of the animal

On a Cyst upon the Olfactory Nerve of a Horse. ie

was greatly interfered with, and probably rendered very
obtuse. But of this, as well as the existence or otherwise of
pain from the pressure of the cyst, we are without means of
ascertaining.

On placing the specimen under the microscope, and viewing -
it with a two-inch object-glass, I was surprised to find a large
octohedral crystal of oxalate of lime, with beautifully de-
fined facets freely floating in a limpid fluid which distended
the walls of the cell. There appeared to be no obstacle to the
passage of the crystal from side to side of the cavity or in any
other direction when the specimen was placed in different posi-
tions, its weight quickly carrying it to the most depending part.
The walls of the cell have every indication of being composed
of layers of areolar tissue spread out in a membranous form ;
they are not, however, of uniform thickness throughout,
although everywhere very translucent. Towards the circum-
ference or periphery of the cell on one side there exists
a bell-shaped spot (a Fig. 1, Pl. 1V.), which is thinly co-
vered with membrane, but surrounded with many fibres, far
more dense than in any other part. Beside the crystal within
the interior there is a small mass of granular-like matter,
which can also be made to vary its position; this mass is
marked b.

The occurrence of this deposition of the oxalate of lime in
this situation is the more interesting from the circumstance
that this salt of lime is very rarely met with in the urine of the
horse, in which the carbonates, on the contrary, are very com-
mon. Various forms of the carbonate of lime are noticed in
the urine of the herbivora, produced by causes disturbing its
ordinary mode of crystallization ; but none of these forms can
be confounded with the octohedral arrangement of the oxalate.

The priority of the formation of the cell or the crystal is not
easy to be determined, it being possible that the blood of the
animal, from impregnation with the oxalate of lime, deposited
this salt in the place it was found, and that subsequently a
cell enclosed it to prevent any serious ill consequences to the
surrounding organism; or it may be that the cell was first
formed, and then the salt was effused into its interior, where
it led to the exudation also of fluid. Itis perhaps right to
mention, in conclusion, that several capillary vessels are to be
observed ramifying upon the walls of the cyst, and that it was
firmly held in its place by fibres of areolar tissue. I may also
add that the crystal has not been measured to ascertain its
exact size, but that it can very readily be seen by unassisted
Vision.

C28)

On the Development of Tubularia indivisa. By J. B. Mum-
MERY, Esq. [Read May 26, 1852. |

Havine found considerable difficulty in reconciling the accounts
given by various naturalists of the development of Tubularia
indivisa, | was gratified to have discovered a locality whence I
could obtain by the dredge a regular supply of fresh speci-
mens of that very interesting zoophyte; and during the past
six months have made almost daily observations by the micro-
scope upon its structure and development.

The painstaking investigations of the late Sir John Graham
Dalyell appear to have supplied much of the information pub-
lished on the subject.

It appeared however to me, on comparing the results of my
own observations with the accounts and figures contained in
the work of that indefatigable observer, that he had ever
laboured under the disadvantage of employing a very imperfect
microscope, and consequently misapprehended some of the
phenomena to which he directed his patient attention.

The general form of Tubularia indivisa has repeatedly been
well described, but there are some portions of its structure re-
specting which greater accuracy appears desirable. ‘The repro-
ductive gemmules have usually been described as origimating at
the base of the lower row of tentacules, and, owing to the pro-
fusely crowded situation of these oviform bodies in the full-
grown head, it is quite impossible to detect their real place of
attachment to the body. It is however a well-known fact,
that the full-grown head within three or four days drops from
the stalk, and that in the course of six or seven days a new head
is produced from the medullary pulp. On examining the
newly-formed head, under a magnifying power of fifty diame-
ters, the oviform gemmules are even at this early stage per-
ceptible, arranged upon the outer surface of the body, and ex-
tending vertically from the lower tentacules to the base of the
oval tentacules in twelve equidistant lines ; two of the lower .
tentacules originating in the space between each ovary, thus
making the whole number twenty-four.

In the early stages of their growth the capsules are attached
to the ovary by a very short and somewhat thick stalk; the
stalk gradually becomes elongated, having the capsules affixed
alternately on each side throughout its length by a broad attach-
ment, and the substance of the capsule is now of a pale rose-
colour.

As development advances the general rosy tint disappears,
and the colouring matter appears concentrated in a well-defined
organ of deep-red colour, which evidently supplies the connect-

Mummery on the Development of Tubularia indivisa. 29 —

ing link between the stalk and the enclosed embryo, and has
been denominated the placental column. The pedicle, attach-
ing the capsules to the stalk, having now become much smaller
in proportion, the stalk, with its capsules, presents the appear-
ance of a bunch of grapes. Sir John Dalyell declares his in- |
ability to discover the ascending and descending currents con-
veying granular matter, which have been observed in the stem
of Tubularia by several naturalists. In addition to these, how-
ever, I have distinctly noticed similar, though not equally ener-
getic currents, in the stem supporting the reproductive gem-
mules.

The writer just named appears to have never detected more
than one embryo in each cyst, but in some specimens I have
found each cyst in the group to contain two, and occasionally
even three embryos, distinctly perceptible through the sides of
the cyst, which is sometimes quite transparent.

While some clusters are fast approaching maturity, others,
attached to the same ovary, are still in the very earliest stages
of growth.

As the contents of the capsules at length arrive at maturity,
a bright red spot (which for some weeks past had become per-
ceptible at the apex of the capsule) is observed slowly to
expand in a quadrangular form, presenting the eppermce
shown in fig. 3, Pl. 1V.

The basal extremity of the nascent animal is now seen
slowly emerging,—the drawing (in the particular instance
illustrated) exhibiting the progress of development at intervals
of an hour, commencing at 8 30 p.m., and concluding at
1 30 a.m., when the process of extrication was complete.
The extremity which will form the future point of attachment
in the fixed state of the young animal is always presented
towards the aperture of the capsule, which appears to be
dilated solely by the efforts of the animal.

Slowly it emerges, withdrawing its tentacles in succession,
until it has set itself free, when it crawls slowly upon the
bottom of the vessel containing it, elevating itself on the
extremities of its eight tentacles.

After a period of time, varying from one to four days, the
animal (which,.in its free condition, has never been remark-
able for activity), having selected a suitable stone, or the
surface of an old polypidon, reverses its position, and, with
the mouth upwards, now attaches itself by the opposite ex-
tremity, and remains rooted fast for life.

In every instance that has come under my notice, the first
animal that escapes is of an ellipsoidal form, not very greatly

30 Mummery on the Development of Tubularia indivisa.

differing from the adult, excepting in the number of its ten-
tacles, Within five minutes after the extrication of the animal
already described, a second escapes through the dilated mouth
of the capsule, but differing greatly from the former in con-
figuration. It closely resembles, in miniature, a young spe-
cimen of one of the star-fishes (Solaster papposa), presenting
a discoidal form, surrounded by twelve obtuse tentacles.

In the course of thirty-six hours this had greatly changed
in form, and, within a few days after, the two varieties pre-
sented but slightly different aspects, especially after they had
fixed themselves. The empty capsule, or ovisac, with its
contained placental column, remains dilated, exactly as when
the young animals quitted it.

After the lapse of about six weeks, the animals, which were
previously colourless, gradually acquire a pale rose tint around
the head, and eventually the ovaries are developed as it ap-
proaches: the adult state.

Much difficulty is experienced in preserving this zoophyte
in a healthy state for examination, but it may be worth ob-
serving that I at length succeeded tolerably well by connect-
ing a syphon of gutta percha with a reservoir of salt water,
and thus causing a small stream to fall from a height of several
feet upon the surface of the water containing the specimens,
and allowing the surplus water to overflow into a larger re-
ceptacle. The agitation thus produced had the effect of
retarding the fall of the heads.

I trust I may be pardoned for referring to the highly in-
teresting suggestion of Professor Forbes, in his admirable
treatise on the naked-eyed Meduse, viz.: That possibly all
the Medusz are, at one period of their life, fixed animals, as
proved by Sars in the case of Cyanea aurita ; and that, con-
versely, many of the zoophytes may be found to pass through
a medium stage of existence, during which the germs are
developed from which the zoophyte is reproduced,—as in the
instances of Laomedea and Cyanea.

As the latter zoophyte presents so close an affinity to the
subject of my remarks, I have most carefully repeated my
observations, and feel convinced that the animal which
escapes from the pedunculated capsule is distinctly trace-
able through all its stages, until, when fixed, it becomes
the adult Z'ubularia, and that it undergoes no intermediate
metamorphosis, or alternation in its mode of existence; I
have thought it possible that the eight-armed creature might
prove a Medusoid.

Col.)

Some Observations on the Structure and Development of
VoLvox GLOBATOR, and its relations to other unicellular

Plants. By Gro. Busk, Esq., F.R.S. (Read May 26, 1852.)

THREE forms, or, as they are commonly regarded, species of
Volvox are described and figured in Ehrenberg’s great work,
and have been noticed by other observers. These are V. glo-
bator, V. aureus, and V. stellatus. A fourth very similar or-
ganism hasalso been described under the name of Spherosira
Volvozx. .

As I regard the three first named of these at all events,
merely as forms or phases of one and the same species, the
following observations will apply in some respects to all of
them. They have more particular reference, however, to the
common form of V. globator, which happens to be that most
accessible to me.

This beautiful and well known object, which was first
noticed by Leeuwenhoek, received little satisfactory elucida-
tion until it fell under the observation of Ehrenberg, whose
account of its structure and notions respecting its nature have
been adopted by most subsequent observers, and have been
received with little opposition until very lately—ain fact until
the beginning of last year. At that time Professor William-
son read a paper on the subject before the Manchester Lite-
rary and Philosophical Society, which is published in the 9th
volume of their Memoirs. ~

Professor Williamson’s observations have led him to con-
clusions in many points opposed to those arrived at by
Ehrenberg, and especially are they confirmatory of Siebold’s
original view of the vegetable nature of Volvor. With respect to
some points of structure, however, concerning which Professor
Williamson differs from the Prussian observer, I am inclined,
from my own observations, to side with the latter, whose
errors in the case of Volvox are not those of direct observa-
tion ; but in this instance, as in very many others, itis obvious
that Ehrenberg has allowed his imagination, working upon
preconceived notions, to play the part of reason in the inter-
pretation of correctly-observed phenomena; he has thence,
in the explanation of what he has seen correctly, fallen occa-
sionally into great and important errors. Whilst it cannot ©
be denied that the recent progress of knowledge with respect
to the structure and nature of the lowest classes of organised
beings, places an observer of the present day in a position so
much more advantageous, that it is scarcely fair to institute a
comparison between him and the great and laborious Prussian
microscopist, at the time his principal works were written,

VOL. I. d

32 Busk on Volvox globator.

still it is much to be regretted that these modern lights, clear
as they are, have not apparently been allowed to penetrate
his mind, and that one to whom science is so much and so
deeply indebted should retain views long since deservedly
exploded by nearly all competent observers.

The more common and best known form of Volvozx ghobdton,
to the naked eye, or under a low power, appears as a trans-
parent sphere, the surface of which is studded with numerous,
regularly placed green granules or particles, and which con-
tains in the interior several green globules, of various sizes in
different individuals, though nearly always of uniform size in
one and the same parent globe.

These internal globes, which are the young or embryo
Volvox, at first adhere to the wall of the parent cell, although
the precise mode of connexion is not very apparent. When
thus affixed, they are in a different concentric plane to the
smaller green granules. Ata later period, and after they have
attained a certain degree of development, these internal globes
become detached, and frequently exhibit a rotatory motion,
similar to that of the parent globe.

In the form of Volvor, termed V. aureus by Ehrenbors,
the outer sphere, or cell, exhibits precisely the same structure
as the above, the only apparent difference between them con-
sisting in the deeper green colour of the internal globules,
These, however, soon exhibit a more important distinctive
character in the formation of a distinct cell-wall of consider-
able thickness around the dark green globular mass. ‘This
wall becomes more and more distinct; and, after a time, the
contents, from dark green, change into a deep orange-yellow ;
and simultaneously with this change of colour the wall of the
globule acquires increased thickness, and appears double.

The third form, or Volvoz stellatus, differs in no respect
from the two former, except in the form of the internal
globules, which exhibit a stellate aspect, caused by the pro-
jection on their surface of numerous conical eminences, formed
of the hyaline substance, of which the outer wall of the
globule is constituted. The deep green colour of the contents
of these stellate embryos, and their subsequent changes into an
orange colour, at once point out their close analogy with those
of V. aureus. Ihave no doubt of their being merely modi-
fications of the latter; and, in fact, the two ” forms are very
frequently to be met with intermixed, and on several occasions
I have observed smooth and stellate globules in the interior of
one and the same parent globe. |

The organism described and figured by Ehrenberg, Uaise
the name of Spherosira volvox, also presents the appearance

Busk on Volvox globator. Sanger

of a transparent globe set with green spots, but it differs from
the foregoing in two important respects.

1. In the absence of any internal globules or embryos.

2. In the irregular size of the green granules lining the
wall, which, instead of being of a uniform size, are of various
dimensions (fig. 13, Pl. V.). The different sized granules are
irregularly disposed, although, in relation to the sphere itself,
they, or rather the centres of them, are as regularly dis-
tributed as in the three just-described forms. What is rather
remarkable with respect to this form is the circumstance, that
the larger granules are not disposed over the whole periphery
of the sphere, rarely occupying more than two-thirds of it,
towards one side. In the more minute description of the
elements of the above-mentioned organisms, the investigation
of which requires the higher powers of the microscope, it
will be convenient to commence with the common Volvox
globator; and as the tracing of the development of the internal
embryonic globules affords the readiest road to a compre-
hension of the true structure of the mature globe, I shall pro-
ceed in that course.

The internal embryonic globules are visible in the young
Volvox while still within the parent; but as they are at first
concealed by the density of the wall of the young Volvoz, the
very earliest stage of formation of the embryo cannot be
readily noticed. In the earliest state in which these bodies
can be observed, they appear as a globular, or rather discoid,
nucleated cell (fig. 3), which, besides its apparent central
nucleus, contains a number of minute spherules placed towards
the periphery. At this time no distinct wall can be detected,
the whole embryo (to use a convenient though incorrect term)
apparently consisting of a homogeneous substance, with a
lighter nuclear-looking space in the centre, and the above-
mentioned spherules towards the periphery. This nucleated
cell, as it may be termed, although without a cell-wall, in-
creases in size, and the solid or coloured contents appear to
retreat from the centre, which becomes clearer and clearer
towards the periphery, which gradually becomes more and more
opaque. As the cell grows, the nucleus (?) seems to disap~
pear, or to be converted into the clear central space; or, it
may be, broken up and confounded in the more opaque con-
tents. ‘The number of spherules increases as the cell grows,
and it is very soon apparent that the now very thick parietal
deposit of cell contents is breaking up into small portions or
lobular masses, the centre becoming clear, and apparently
filled only with a clear aqueous fluid. When the cell has
thus acquired a considerable size, the contents begin to un-

d 2

34 Busx on Volvox globator.

dergo segmentation, as pointed out in the case of Volvox—l
believe first by Professor Williamson. This process com-
mences and proceeds precisely as in the ova of animals—the
contents dividing first into two, and then each of the halves
into two, and so on, till the division becomes too minute to
allow of the counting of the segments. It is to be remarked,
moreover—and I think this has not been noticed before—that
the bright spherical bodies multiply quite as rapidly, if not in
a more rapid ratio, up to a certain point, than the segmenta-
tion goes on, so that each segment of the still-dividing mass
always exhibits two, three, four, or even more of these par-
ticles (figs. 1, 2). Ultimately the segmentation ends in the
formation of innumerable green bodies, which are closely
packed round the periphery of the cell. These bodies, though
perfectly defined, are not at first separated by any clear space,
and each contains at least one of the bright spherules alluded
to (fig. 3). By their mutual pressure, these soft corpuscles of
course assume an hexagonal figure, and they are now about
1-4000th of an inch in diameter, or rather more. As soon as,
or even before, the segmentation commences, a distinct though
delicate membrane, surrounding the embryonic mass, is quite
evident, as described by Mr. Williamson; and beyond this is
usually to be observed a very delicate zone of apparently
gelatinous matter, which is sometimes so delicate as to escape
observation, but may, I believe, always be detected by the
use of a solution of iodine.

When the segmentation is completed, in the way above de-
scribed, the embryo Volvoxz exhibits the appearance of a sphe-
rical body composed of a transparent membrane lined with
distinct, uniform-sized, contiguous hexagonal masses, It con-
tinues to grow, and very soon clear lines become apparent
between the green masses, which are thus very distinctly
defined, retaining the same hexagonal form—each with an
apparent nucleus, which is probably derived from the bright
spherule contained in it, but as yet without brown spot, clear
space (vacuole), or vibratile cilia. As the embryo continues to
grow, the spaces between the green masses continue to in-
crease ; the green bodies gradually lose the hexagonal form,
and assume the appearance of the ciliated zoospore next
to be described, ‘They are now about 1-3000th of an inch, or
thereabouts, in diameter, and the embryo, detached from its
parent, becomes a free Volvox in its interior. We have thus
arrived at the complete Volvox, and from the mode of its for-
mation it is apparent that it consists of a transparent wall
lined with the green bodies, and hollow in the interior; and
also that it is surrounded, at all events while within the

Bus on Volvox globator. | 30

parent, with a delicate transparent areola, apparently of gela-
tinous matter We have now to examine more minutely the
structure and nature of the green granules, and the further
changes they undergo.

Upon examination of the wall of a full-grown V. globator
with a sufficient magnifying power, it will be seen, upon view-
ing the edges, as it were, of the image in the field, with the
object so arranged as to bring the equatorial plane exactly into
focus (fig. 5), that the green granules are, in fact, vesicular or
semivesicular bodies of a flask-like or conical form, about
1-3000th of an inch in transverse diameter, and placed at
uniform distances apart. Each of them is prolonged out-
wardly into a sort of peak or proboscis of a transparent and
colourless or hyaline material, and from which proceed two
very long vibratile cilia, which in close contact at first, pass
through the parent cell-wall, upon the outer side of which
they separate widely and perform very active movements. The
outer cell-wall presents a minute infundibuliform depression at
the point of exit of the cilia. It will also be observed, that
each ciliated cell or zoospore, as it may analogically be termed,
contains a green granular mass or masses, composed, for the
most part probably, of chlorophyll granules and a more trans-
parent body, which I suppose may be regarded as a nucleus,
and derived, as it would appear, from one of the bright sphe-
rules which have been noticed before. Atan early period after
the maturity or completion of the zoospores they exhibit a
minute, circular, clear space, or sometimes, but I think rarely,
more than one, which is worthy of very attentive considera-
tion. This space is of pretty uniform size in all cases, and
about 1-9000th of an inch in diameter. It may be situated in
any part of the zoospore, or not unfrequently in the base, or
even in the midst of one or other of the bands of protoplasm
connecting it with its neighbours. Its most important charac-
ter consists in its contractility—a property already known to
be possessed by similar spaces or vacuoles in vegetable spores.
But what appears to me a very curious, and as yet unnoticed
peculiarity of this contraction, consists in the fact that it is
very regularly rhythmical. In several cases in which I have
watched the phenomenon in question, uninterruptedly, for some
time, the contractions or pulsations occurred very regularly at
intervals of about 38” to 41”. In one case, however, if I was
not misled in the observation, the interval was about twice
this, viz., 1’ 25”. The contraction, which appears to amount
to complete obliteration of the cavity of the “vacuole,” takes
place rapidly or suddenly, as it were, whilst the dilatation is
slow and gradual, The interval above noted was measured

36 Busk on Volvox globator.

between one sudden contraction and the next, and about half
of it perhaps was taken up by the slow dilatation of the space.
This contractile vacuole always reappears in precisely the same
spot. It would seem to exist, or at all events to present a
contractile property only for a limited period, and to disappear
soon after the formation of the brown spot, when, as I con-
ceive, the zoospore has reached its maturity. The most
favourable cases in which this contractile space is to be sought
for, are those in which the Volvox is in the most vigorous state,
and especially in that variety in which, owing perhaps to the
copious supply of nutritive matter, the amount of protoplasm
is very abundant, and the zoospores consequently very numer-
ous and connected to each other, not by slender filaments but
by wide processes, as in figs. 26, 27, which latter shows a
contractile space situated in the base of one of the connecting
bands of protoplasm, With the exception of the small space
occupied by this contractile spot, the zoospore at first appears
to be quite solid, and no distinct wall can be perceived around
the green matter, but it rapidly changes. Owing either to the
_expansion of the vacuole, above described, after it has lost its
contractile property, or to the formation of others ofa different
nature, and also perhaps in some degree to the absorption or
consumption of some of the colouring contents, the zoospore
gradually becomes more and more transparent (fig. 7); till at
last, the greater part of it is clear and colourless, and what
remains of the green matter contracts into a small irregular
mass, adherent to the bottom or sides of what is now a cell—
primordial cell of Cohn. (Figs. 5, 6.)

Each cell, when fully formed, usually presents a brown
spot, which is adherent to one ade of the cell towards the
narrow end (figs. 5, 6); and what is remarkable, it will be
noticed in a perfect specimen, that the brown spots are placed
in a corresponding situation in all the cells, that is to say, all
the cells appear to look the same way. This is the so-termed
eye-spot of Ehrenberg. When examined with a high power
(800—900 diam.) it presents the form of a cup or disc, con-
cave on the side which looks outward, and convex on the
other. ‘Though placed quite on the side of the cell, and pro-
jecting a little upon it, the brown spot is nevertheless always
covered by a thin membranous expansion of protoplasm, or, in
other words, it is always lodged within the substance of the
zoospore. ‘Though most usually present, the brown spot does
not appear, in all cases, to be at any period a necessary con-
stituent of the zoospore. It is one of the most persistent
however, remaining visible as long as any portion of the zoo-
spore is discernible. Besides the above-described elements, the

Busx on Volvox globator. 3 37

zoospore, when viewed from above, exhibits two highly refrac-
tive spots placed side by side, white seerh to represent the
insertions or origins of the two vibratile cilia.

The periphery of the cell presents a clear line, and appears
to be formed of a delicate membrane—although, in the earlier
stages of the existence of the zoospore, that is, before the for-
mation of the eye-spot, or disappearance of the contractile
vacuole, the whole evidently consists of a homogeneous sub-
stance, in which the above described parts are imbedded,
From the periphery of the zoospore proceed six thread-like
processes, connecting it with as many of its neighbours. These
threads appear to be simply continuations of the quasi? cell-
wall, and to be of the same nature chemically as it, as are also
the vibratile cilia. The connecting threads are sometimes
double, or even triple, between some one or more of the sur-
rounding cells, and they are invariably continuous between the
two cells.

This description applies more particularly to the zoospores
in situ. When the Volvox is ruptured, many appear to be-
come immediately detached, and to be washed out, as it were,
with the aqueous contents of the parent cell. Under these
circumstances they lose some of their previous regularity of
form, but not much; they become more globular and the
beak less prominent, but in other respects they appear much
the same as before. The two vibratile cilia remain in @on-
nexion with them, and continue their active movements. This
is opposed to Mr. Williamson’s statement, that ‘‘ when thus
liberated they exhibit no traces of the two cilia, or probos-
cides” of Ehrenberg, and agrees with that of the latter.
Among the thus liberated ciliated zoospores will usually be
found numerous detached cilia, which, as is observed by Mr.
Williamson, are generally more or less coiled at one end into a
ring. And besides these I have not unfrequently noticed some
extremely delicate annular bodies, about 1-9000th of an inch
in diameter, perfectly clear and colourless, which seem as if
they had escaped from the interior of the ruptured zoospore:
but of this and their true nature I am unable to speak posi-
tively.

Having thus described what I conceive to be the anatomy of
the common form of Volvox globator, 1 will thus sum up the
result of what my observations have led me to conclude as to
its structure.

1. That it originates in an apparently nucleated, discoid
cell, which is generated in the interior of the parent, and
liberated in a perfect, though not fully matured form; within
which are contained similar germs.

9

os Busx on Volvox globator.

2. That the contents of this apparently nucleated discoid
cell, consisting of a grumous material and refractive amyla-
ceous (?) spherules, after a time undergo segmentation, at
the same time exhibiting a distinct wall, beyond which is a
delicate areola, apparently of a gelatimous consistence.

3. That this segmentation, attended with a corresponding
augmentation in the number of the refractive spherules, ter-
minates ultimately in the formation of numerous contiguous
particles or segments,

4. That these ultimate segments are gradually separated
from each other, remaining connected only by elongated pro-
cesses or filaments, and constituting the ciliated zoospores of
the mature Volvoz.

). That these zoospores at first are simple masses of pro-
toplasm, containing a transparent nuclear body, and _ that
afterwards they present for a time clear, circular spaces, which
contract rhythmically at regular intervals ; and are subsequently
furnished with a brown eye-spot; and at a very early period
with two long retractile cilia, which, arising from an elongated
hyaline beak, penetrate the parent ‘cell-wall, and exert active
movements external to it.

6. That in a concentric plane internal to these ciliated zoo-
spores are placed the germs of future individuals destined to
follow the same course.

aving thus traced one form of Volvox through its course BE
development, I will proceed much more briefly to the others.

In V. aureus, as I have said, the constitution of the wall of
the parent cell is exactly as above described. At its earliest
appearance also the internal embryonic body cannot be dis-
tinguished from that of the ordinary form, except in its deeper
green colour. It afterwards, however, acquires a thick wall,
changes its colour to yellow without material alteration in size,
and acquires a second equally firm and distinct envelope, or
rather, as I believe, the original contents contract somewhat,
and then form a second coat around themselves. Eventually
a considerable space exists between these two coats (figs.
10, 12), which space is occupied by a clear and apparently
aqueous fluid, but upon the addition of a solution of iodine a
granular Glomdinces 4s produced in this fluid. The contents of
the inner cell consist chiefly of amylaceous grains mixed with
a greenish material in the one case, and with a bright yellow
apparently oily fluid in the other. The amylaceous particles
are of an irregular botryoidal form, and far from uniform in
size. As regards the future destination of this form of germ,
I am as yet in total ignorance ; there can, however, I think, be
little doubt but that it represents the ‘‘still” form of spore of

Busx on Volvor globator. | 39

other Alga—that it may, in fact, be termed the “ winter
spore” of Volvox, destined, owing to its more persistent vi-
tality, to continue the species, when its course of development
in the usual way is interrupted by surrounding circumstances.

Of that form of Volvor termed V. stellatus, 1 would only
here observe that it seems to me merely a modification of the
one last described, and that it appears to follow the same
course of change and doubtless of future development.

With respect to Spherosira volvox, my observations have
been very limited, and I by no means desire to express myself
with certainty as to its relationship to the forms above de-
scribed, I merely surmise that it may be found to represent
a peculiar mode of development of one and the same species.

In external aspect, except in the want of uniformity in the
size of the ciliated zoospores, it appears to agree in all respects
with V. globator. It however contains no internal embryonic
bodies, and it is therefore only to the ciliated cells that any
reference need here be made. The smaller ones appear to
me to resemble in all respects those of Volvox globator, and
each to possess two cilia, which is important if true, because
the only distinction between Volvox and Spherosira in Ehren-
berg’s classification depends upon the circumstance, that in
Spherosira there is only a single cilium to each zoospore, whilst
there are two in Volvoz. |

My supposition that Spherosira volvox and V. globator are
allied, is founded, it must be owned, not upon any direct ob-
servation, but chiefly upon the fact, that in the water in which
the specimens of Volvox I had under examination were con-
tained, there was at first none of the Spherosira any more
than of V. aureus observable, and that after some days both
were very numerous.

The difference I am about to describe in the after develop-
ment of the ciliated zoospores, is not by any means a sufficient
ground upon which they should be deemed distinct species,
because much greater differences are known to exist in other
of the lower Algz during their various forms of development
without its being thence allowable to suppose that they are of
different species.

In Volvox spherosira then, as at all events it may be termed,
the larger green granules are in fact the ciliated zoospores in a
stage of further progressive development. In the same spe-
cimen they will be seen in all stages of division or segmenta-
tion (fig. 13)—first into two, then into four, and so on till, as
in the case of the embryo Volvoz, the ultimate result of the
segmentation constitutes numerous minute ciliated cells or
bodies (fig. 14)—not, however, as in that case, lining the

40 Busx on Volvox globator.

inner surface of the wall of a spherical case, but forming by
their aggregation, a discoid body, in which the separate fusi-
form cells are connected together at one end, and at the
other are free, and furnished each with a single cilium, In
this stage these compound masses become free and swim
about in the water, constituting, in fact, a species of the genus
Uvella, or of Synerypta of Ehrenberg.

With respect to the chemical constitution of the above
described parts, the following are the results at which I have
arrived :—1. By the use of iodine and sulphuric acid, tried
repeatedly and in various ways, I have never succeeded satis-
factorily in eliciting any tinge of blue in the wall of the mature
Volvox. I therefore conclude that it contains no cellulose. It
is invariably coloured, by the above re-agents, of a deep brown
colour, and when thus coloured, this outer wall presents no
trace whatever of structure; it appears uniformly transparent
and homogeneous. The ciliated zoospores, also, with the
connecting filaments and cilia, are turned brown, but of a very
deep brown, by the same re-agents, excepting usually one or
more particles in the interior of each, which are apparently
turned blue, I am not satisfied as to the chemical re-action of
the brown spot; it appears to assume a blue colour, but from
the intensity of its colour and consequent opacity I am not
sure that this is the case.

The embryo cell, when young, is turned a deep brown,
but when older and fully formed, but before it has arrived at
maturity, it will be found that it is only the green masses, or
future ciliated zoospores, that are thus changed, the cell-wall
acquiring scarcely any tinge of brown. But when a young
cell thus tested with iodine and sulphuric acid is ruptured, I
have occasionally noticed that the fluid contents contain an
abundance of minute bluish flocculi—I use the word flocculi
because the particles are light and flocculent, and not at all like
any of the more ordinary and more solid forms of amylaceous
matter. The quantity of this flocculent matter appears to be
greater towards the periphery of the cell, and, in fact, it would
seem that the green bodies are at this time imbedded as it were
in an amylaceous matrix, which they not improbably assimilate,
because in the mature cell nothing of the sort is apparent.

In the embryonic bodies, however, or winter spores of
V. aureus and stellatus, the presence of cellulose is rendered
abundantly evident in the two coats forming the tunic of the
spore by the blue colour produced in them by iodine and sul-
phuric acid (fig. 11); nearly as distinctly, in fact, as it is in
the tunic of Micrasterias and other Desmidiee. 'The appa-
rently clear fluid between the two tunics is rendered brownish

aa

Busx on Volvox globator. 4]

and turbid at the same time (figs. 11, 12), and the solid con-
tents of the interior are shown to consist, for the most part, of
amylaceous grains of the peculiar botryoidal form above
noticed. (Fig. 9.) The yellow oil-like fluid in the ripe
spore acquires a green tint under the action of the same
re-agents. (Fig. 9.) ;

ot

AppENDIx.—( October, 1852.)

The above are the observations read at the Microscopical
Society. I am now satisfied that they afford an account of
but one of the multiform varieties under which Volvoz occurs
at different times and places. I must own also, that at the
time my observations there detailed were made, I was unable
to reconcile much of what I saw with some of the statements
and figures in my friend Professor Williamson’s ingenious
paper on the same subject. Subsequent investigation, how-
ever, and some correspondence with him, have satisfied me that
I was hasty in drawing conclusions from one form only of a
very protean object. I freely confess, that in much, in respect
to which I had conceived Professor Williamson had fallen into
some error of observation, he has been quite right, though at
the same time I must say that his explanations of the appear-
ances described and figured by him, do not exactly accord with
my notions respecting them. I still maintain that the structure
of the wall of Volvor—upon which alone I think we are dis-
agreed—is essentially such as I have described it, viz., that it
is formed by acontinuous, external tunic, lined by the ciliated
zoospores. Professor Williamson, on the other hand, as I
understand him, conceives the globe to be ‘a hollow vesicle,
the walls of which consist of numerous angular cells filled with
green endochrome, &c., the intercellular spaces being more or
less transparent.” The ciliated zoospore, therefore, according
to him, is not a mass of vegetable protoplasm, without dis-
tinct wall, and precisely analogous to a Huglena, or other
naked zoospores, but represents the endochrome of a cell hav-
ing two walls, an external and an internal, which latter is “a
ductile cell-membrane, lining the interior of each cell and sur-
rounding the cell-contents,” and which ‘‘ inner membrane be-
comes separated from the outer cell-wall excepting at a few
points, where it is retained in contact.” And he thus explains
the mode of formation of the connecting filaments. In this
case, therefore, these filaments would never pass directly from

‘one green mass to another, but. would of course be interrupted

in their course by the walls of two contiguous cells. That this,

42 Busk on Volvox globator.

however, is not the case in the form of Volvoz, which formed
the subject of my paper, is sufficiently obvious. But it is
nevertheless true, as I find from examination of Professor Wail-
liamson’s specimens, that his representation is, in certain cases,
equally correct, as I shall afterwards explain. Another cir-
cumstance also noticed by Mr. Williamson, and which, till he
pointed it out particularly to me, had, though not altogether
unnoticed, been disregarded, is the existence of delicate lines
between the green granules, and dividing the wall of the Vo/-
vox into very regular hexagonal spaces, in the centre of each of
which is placed one of the green granules. ‘The former of these
conditions— which, though I have never met with it myself
distinctly in specimens from any other locality, seems to be
sufficiently abundant in the neighbourhood of Manchester—is
represented in figs. 15, 16, 17, 18, 19, 20. In these it will be
seen that the central green body is surrounded, at variable dis-
tances, by a tolerably thick, distinct membrane or wall, and
that numerous irregular filaments, where they exist at all,
extend from the central mass to this wall, and there terminate,
and do not pass from one green mass to another, as in the
usual form. Now, I explain the way in which the zoospore is
thus modified, in this way: I regard the external membrane
merely as the boundary-wall of the original zoospore, and, like
the entire body, as composed of vegetable protoplasm; and I
believe that this peculiar appearance is produced by a great
and unusual expansion of the interior of the zoospore (by
endosmosis of fluid probably), by which the outer or periphe-
ral layer is separated from the remainder and principal part of
the mass, containing the chlorophyll and nucleus, or supposed
nucleus, &c. Zoospores, in fact, in this condition might be
said to be dropsical. ‘That this separation of the wall from
the contents arises in this way, and not, as Mr. Williamson
says, from the shrinking of contents, is, I think, sufficiently
obvious from several considerations, and is rendered very clear,
if we trace the progressive stages of the hydropical enlarge-
ment in one and the same Volvoz, as I have done in the figures
above cited.

In this series it 1s easy to observe the earliest formation of
the clear space up to the most extreme dilatation of which
the cell is capable, owing to its contiguity with others. Of
course when a number of cells are thus enlarged and mutually
compressed, they assume an hexagonal form; but this hexa-
gonal arrangement must not, as it appears to me, be con-
founded with another, to which I have before alluded, and
which I conceive to be due to a different circumstance alto-
gether. In fig. 15 of this series, some cells will be obseved

Busk on Volvox globator. 43 ©

little if at all altered, from what I assume to be the normal
form, and it will be seen that these little altered cells are
mutually connected by the usual continuous filaments. In
fig. 16 the zoospores are more expanded, and being in con-
tact in many points, the connecting threads are absent;
fig. 17 shows a further degree of expansion, but more irregu- ©
lar, and with irregular connecting filaments. In fig. 18 the
enlargement is nearly as great as it can be, and numerous
threads or processes of protoplasma extend from the central
mass to the wall, just as they do in almost any vegetable cell
from the nucleus to the primordial utricle, which utricle, in
fact, 1s represented by the cell-wall in the case we are dis-
cussing. In fig. 19, the dilatation is complete, and, owing to
the greater age of the specimen from which this figure was
taken, the protoplasma is much wasted, and all the filamentary
processes completely gone. A faint granular appearance
occupies the cavity of the primordial cell. It is a curious
fact, as showing perhaps that all the vital action in the cell
resides in or around the nuclear mass, that not unfrequently the
central mass after considerable expansion of the cell, and the
formation in that way of one wall, will begin to throw off
asecond. ‘This condition is represented in a more highly
magnified drawing in fig. 20,

Although I have not myself seen any natural specimens in
which this condition of the zoospores was present, except those
for which I have been indebted to Mr. Williamson, still I
have repeatedly observed a partial appearance of the same
kind to take place, when a specimen of Volvoz of the normal
sort is kept for some hours under observation in the micro-
scope. Figs. 21, 22, 23 show the series of changes that
took place in a certain number of zoospores watched at
intervals, and left undisturbed for about twenty-four hours.
(Fig. 21,10 am., Oct. 4. Fig. 22, 1 p.w., Oct. 4. Fig. sia
8 A.M., Oct. 5. )

Now with respect to the other form a hexagonal areo-
lation, for my knowledge of which, as I have stated, I am
chiefly indebted to Professor Pluamecd and hee 1s
represented in figs. 24, 25, I have already observed, that I
regard it as quite distinct from that produced by the mutual
pressure of contiguous dilated zoospores. Professor William-
son appears, from what he has told me by letter, to consider
that this appearance is invariably present, or at all events that
it can be elicited in all cases by appropriate means. I must
confess however, that I have not been successful in seeing it,
or in producing it in very many instances, and that I believe it
is occasionally impossible by any means to demonstrate its

44 Busx on Volvox globator.

existence. At some periods not a single specimen from a
given locality will exhibit it, whilst at another, every indi-
vidual will show it at the first glance. Thus in the month of
_August last, when, in a certain pond on Blackheath there was
the most incredible abundance of Volvoz, so great in fact as to
render the water at the lee side of the pond in certain spots
of a deep green colour, and to cause it to afford, when collected,
a very strong herbaceous or confervoid smell, the majority
of the plants exhibited the stellate form of spores, or rapidly
acquired spores of that character, and very many were in, or
soon assumed, the form of V. aureus. ‘They seemed in fact to
be entering upon their hybernating state. Many among them,
however, though all small and starved-looking, were of the
common kind ; in all these Mr. Williamson’s hexagonal areola-
tion was very distinct. In the month of October, however,
upon returning to the same pond, I was able to find very few
Volvoces at all, and all of the usual kind ; in none of these could
I detect the least appearance of the same arrangement. I there-
fore conclude that the greater or less distinctness, or complete
absence of this character, is to be referred to external condi-
tions with which we are not fully acquainted. The appear-
ance itself I explain in this way. It appears to me that each
zoospore is imbedded in a distinct gelatinous or semi-fluid
envelope of considerable thickness, and that the hexagonal
areas are formed by the sides of these distinct masses of gelati-
nous matter coming into contact. I am inclined to think that
there is no distinct membrane containing this gelatinous matter :
if there be, it must be infinitely thin, because the line of con-
tact is extremely delicate and single. I conceive, in fact, that
each ciliated zoospore is surrounded with a gelatinous or
semi-fluid areola, of the same nature precisely as that which
surrounds the embryo Volvox while within the parent, and
in which also it is not I thmk possible to detect a distinct
limitary membrane. This envelope of the ciliated zoospores
contains a nitrogenous element, which sometimes, on the addi-
tion of iodine, gives rise to the appearance of minute heads
around the outer periphery of each gelatinous mass, or in the
lines of the hexagonal areas as seen in fig. 25. It is to be
observed also, that connecting filaments of protoplasma may
occasionally be seen to pass from one zoospore to another
across the line of junction of the two gelatinous envelopes
(fig. 24). These zoospores therefore of Volvox would appear
to represent the ‘‘encysted zoospore”’ of Cohn (Protococcus
pluvialis, &c.), and his fig. 43, plate 67, may perhaps be
taken as a fair representation of what I conceive to be the
condition in these connected zoospores in Volvox. This ex-

Wixiramson on Volvox globator. 45

planation of the hexagonal areolation, however, does not clash
at all with that which I have given as to the structure of the
-wall of Volvox. For in this case, as in all others, the collected
mass of zoospores, and their envelopes, is enclosed by a con-
tinuous external membrane, not in any way derived from them
but from the parent cell in cwisch they were originally formed.
There are several other interesting points relating to Volvox
which have come under my observation ina prolonged atten-
tion to the subject, including another form of development of
the internal spore, in which it divides, not in the usual way,
into what may perhaps not inappropriately be considered as
macrogonidia, to use Braun’s expression, but into a much
smaller and differently arranged sort, which may be considered
as his microgonidia; but to enter fully upon this and other
points would demand more space than is here at command.

[Whilst this paper is passing through the press, I have
found that a faint, but quite distinct, purplish blue tinge may
be produced in the wall of Volvox globator by means of
Schultz’s solution, The specimens of Volvox in which I
have noticed this have been preserved in glycerine for two

months.—G. B.]

Further Elucidations of the Structure of Votvox GLoBATor.
By Professor W.C. Wittiamson. (Read June 21, 1852.)

In May, 1851, I had the honour of laying before the Philo-
sophical Society of Manchester a memoir on the Volvox globa-
tor,* containing the results of a series of observations, which
brought to light in that elegant object, a cellular structure,
hitherto unobserved. Since the existence of these cells affects
the character and affinities of the organism, it is desirable
that the fact should be established beyond the possibility of
dispute. My friend Mr. Busk, in a recent communication
made to the Microscopical Society of London, either doubts
their existence, or rejects my idea of their cellular nature.
This denial, coming from such a quarter, renders it incumbent
upon me to make the matter more plain than was done in my
previous memoir: I am enabled to do this, partly by new ob-
servations on the living Volvoz, and partly by some changes
which the specimens prepared last year have undergone,
making their structure more obvious than it previously was.

* Published in the Ninth Volume of its Transactions.

46 Wit.iamson on Volvox globator.

No one who has seen these specimens can for a moment
doubt that there exists immediately beneath the superficial
pellicle, or common investing membrane of each Volvox, a
layer of closely-packed translucent vesicles, within each of
which is located one of the numerous green spots ornamenting
its periphery. In the memoir referred to, I endeavoured to
show that these vesicles are true cells, whilst the green spots
are the inner cell-membranes and their contents, representing
the internal utricles of Harting and Mulder, the primordial
utricles of Mirbel. The appearance of these cells in their
different stages of growth was described, and the mode of
their development and multiplication examined.

Mr. Busk, who has recently directed his attention to this
subject, has arrived at a different conclusion from my own,
respecting the structures in question. Not having, then, seen
the hyaline vesicles, which I regard as true cells, in any of his
own specimens, he concluded that the Volvox consists of a
number of protoplasms, which have resulted from the suc-
cessive segmentations or subdivisions of one primary pro-
toplasm, in the way described in my memoir. On being
afforded an opportunity of examining some of my preparations
of Volvox made last year, and in which the vesicles are re-
markably distinct, though the appearance they presented was
wholly new to him, he was still disposed to maintain his pre-
vious opinion. Instead of admitting them to be true cells,
he concluded that they were merely the outer layers of the
protoplasmic segments, which, after separating from the pro-
toplasmic mass, had become dropsically distended, and as-
sumed the appearance of a true cell.

Since I believe this general conclusion to be incorrect, I am
anxious to render more clear than I have hitherto done, what
appears to be the true interpretation of the structures in ques-
tion. In accomplishing this, it will not be necessary to reca-
pitulate all the details of my preceding memoir, since the
accuracy of the greater number of them, as well as my con-
clusion respecting the vegetable nature of Volvox, are con-
firmed both by Mr. Busk and by other observers: some
points, however, require to be examined in detail,

There is one point respecting which I was clearly in error ;
my present correction of the mistake is due to the suggestions
which I have received from Mr. Busk. I found that each
young germ was developed from one of the peripheral stratum
of cells, by the ordinary process of cell-division or segmenta-
tion. Having ascertained that each protoplasm in its matured
state was invested by a true external cell, in addition to a very
thin inner one which held the granular mass together, I con-

Wituiamson on Volvox globator. 47

cluded that, in the earlier stages of the process of segmentation
and development of the germ, each protoplasmic segment
would be invested by a similar external cell-membrane, as is
the case with Hematococcus, Palmella, &c. I could not ascer-
tain what became of these outer cells, as successive subdi-
visions of their contained protoplasms multiplied their number,
but hazarded the surmise, that the earlier cells might either
have been re-absorbed, or that they still existed in the form of
thin membranes, consolidated with and investing the newer
cells which I supposed had been developed within their in-
terior. It is now obvious that none of the protoplasmic seg-
menis have secreted their external cell-membrane, until the
entire number destined to compose the matured organism has
been completed. This interpretation accounts for many ano-
malous circumstances. It explains the very close contact in
which we find the green protoplasms of the immature germ.
No transparent spaces intervene ; these only appear when the
young germ is matured and furnished with cilia. It also
explains my want of success in searching for the layers of
cellulose, the residue of the supposed earlier-formed cells,
which must have existed had the organism been developed in
exactly the same way as a Palmella or an Hematococcus. In
these latter objects, each segmentation of the protoplasm ts
followed by the secretion of a true cell, which invests each
segment.

The point now to be demonstrated is the existence of two mem-
branes surrounding each mass of protoplasm. First an inner
one, very thin, and in the living state, closely embracing the gra-
nular protoplasm, and corresponding with the inner cell-mem-
brane of the ordinary Conferve ; second, an outer cell-mem-
brane secreted from the exterior of the first. To facilitate
describing, we may term the former of these the protoplasmic
membrane, and the latter the cell-membrane.

The protoplasmic membrane is easily shown to exist. Fig.
6, Pl. VI. represents a very young gemma, or budding germ,
which consisted of but few segments, as it appeared when sub-
jected to pressure under water. Some of the protoplasmic seg-
ments glided through an aperture made in the common vesicle,
without becoming ruptured. They accommodated themselves
to the size and form of the aperture, and, on escaping, regained
their spherical form. On increasing the pressure, each seg-
ment burst, all the granular and mucilaginous contents flowing
out and mingling with the water (60'). Asthey did so the
protoplasmic membranes (6c) were distinctly seen as thin
hyaline spheres. In the subsequent development of Volvox
this membrane always continues in existence. Its appearance

VOL, I. e

438 ~Wiuramson on Volvox globator.

in the matured organism will be described immediately. When
the gemma has attained its full size, by the process of segmenta-
tion described in my former memoir, further changes occur.
Translucent spaces separate the green protoplasms, now be-
come hexagonal by mutual pressure. These translucent out-
lines mark the development of the external cells investing the
protoplasmic membranes. At first the two are in close oppo-
sition; they subsequently separate, as the cell increases in
s1ze, excepting at certain points where they remain in contact.
Before tracing out the further stages of this process I must
observe that the Volvox exhibits two apparently distinct states,
which are, nevertheless, mere varieties of one species. In the
one, each ‘protoplasm assumes the appearance of fig. 1 5, being
angular, and giving off thick, irregular and often dichotomons
fovende (he) athe cximenniaes of which are attached to the
cell-wall (1a). In this case, the radiating threads consist not
only of the protoplasmic membrane, but also of its granular,
mucilaginous contents. The other condition referred to is
represented in fig. 10. Each protoplasm (10d) is perfectly
spherical, and connected with its neighbours by delicate capil-
lary threads, these being so fine as to be sometimes almost
invisible. In this state the cells to be described are often
invisible ; nevertheless, they exist.

The changes undergone by the stellate variety were described
in my previous memoir. The cell expands, and as the pro-
toplasm is only attached to it at certain points, the latter is
drawn out until it finally assumes the stellate contour deli-
neated in fig. 1. Each of the radiating threads is attached to
the cell-membrane by its peripheral extremity, at a point
exactly opposite the corresponding threads of contiguous pro-
toplasms. On rupturing a Volvox under water these threads
become detached from the cell-wall, and passing through the
stages represented in figs. 2 and 3, assumed that of fig. 4,
which is precisely that of fig. 10, minus the connecting threads,
a state which occasionally occurs in the living Volvox.

In numerous examples of both these varieties of Volvox |
found each protoplasm surrounded by an angular, usually
hexagonal, areola, as represented in fig. 5 of my original me-
moir. They appeared as dark outlines when the object was
illuminated by transmitted light. On exposing these speci-
mens for a while to the action of some re-agents, as glycerine,
I soon found that each dark line was really double, and marked
the boundaries of two cells. This was shown by the gradual
separation of these cells at the angles of the areola, as repre-
sented. in fig. 11, which is a faithful transcript of part of one
of these specimens when mounted in glycerine. In this ex-

WixiiamMson on Volvox globator. 49

ample no cells were at first visible ; but as I watched them, they
came gradually into view in some parts of the organism, but
not in others. Fig. 11 represents a portion of it, in the upper
part of which the cells are visible, whilst in its lower part
they cannot be traced; here the tissues were transparent and
apparently quite structureless, as was the entire sphere in the
first instance. The transition from the one condition to the
other was gradual; the dark lines becoming less conspicuous
and finally disappearing as we approached the opposite side of
the Volvox to that on which they were most distinct. ‘This
specimen illustrates thousands that have been examined, and
proves that the apparent absence of the cells from so many of
the objects is no proof that they do not exist, but merely shows
that certain favourable conditions are required to bring them
into view. We are justified in concluding that they exist alike
in all the specimens of Volvox, and are not merely accidental
developments in a few individuals.

In my mounted preparations we obtain further evidence
respecting the nature of these two membranes—the proto-
plasmic and the cellular. We see that the wall of the sphere
has an appreciable thickness, the inner margin being as
definite as the outer one, and nearly parallel with it. Fig. 5
represents this as seen ina section of a Volvox. A moment’s
Inspection of my preparations would convince the most
sceptical that such is the case; several of these peripheral
cells, as seen in the section, are more highly magnified in
figs. 14 and 15. The thin investing pellicle (15 d) com-
presses the outer wall of each cell into conformity with the
peripheral curve of the sphere; laterally the septa (15 a) are
straight and parallel to one another. Internally, each cell is a
little turgid (15 a), the centripetal pressure at this point being
obviously at the minimum, and allowing the primary tendency
of the cell to assume a spherical form to manifest itself. The
green protoplasm adheres firmly to the peripheral wall of each
cell, through which the cilia are protruded. Between the
true cell-wall and the protoplasm, we have the protoplasmic
membrane (14 and 15 cc’) in variable conditions. Some-
times it forms an oval cell (14 e’), sometimes it is oval at one
end and flattened out at the other (14c, 15c’); at others it is
not only flattened out at each extremity and in close opposi-
tion with the cell-wall, but even at the two sides (as in the
centre cell of fig. 15) the two membranes are closely ap-
proximated.

If we turn to a superficial view of the same specimens, we
_ shall obtain similar results. It must be borne in mind that
in the living Volyox, even where the cells are visible, we only

e2

50 Wixtiamson on Volvox globator.

see the true cells ; the protoplasmic membrane being in such
close apposition to its granular and mucilaginous contents as
to prevent its being identified as a separate tissue. But
when the specimens have been mounted some time, we often
find that a change takes place. The protoplasmic matter
shrinks up into a small irregular mass (7 6), and thus becomes
detached from the protoplasmic membrane (7 c¢, c') which forms
a ring round it. When we succeed in compressing the object
so as to force the cells into an oblique position (as is done in
those to the left of fig. 7), we see that these circles are really iden-
tical with figs. 14 and 15 c, c’ in the sections. The external
cells (7 a) remain in mutual contact, excepting at their angles.

There is a little discrepancy between this description and
that of fig. 11 in my former memoir, and the explanation of
its cause will do much to diminish the real difference between
myself and Mr. Busk, whilst it tends to confirm my ideas
respecting the cellular structure of Volvox. In many of my
mounted specimens, the outer or cel/-membranes have either
failed to become visible, or have disappeared again. On the
other hand, in these examples, the protoplasmic membranes
have separated from their protoplasms and become very con-
spicuous. I formerly confounded the two, and imagined that in.
the latter examples the incipient separation of the cells at the
angles (seen in figs. 11 and 16) had been subsequently carried
much further, causing a complete isolation of the cells, as is:
apparently the case in fig. 17. My error was corrected by the
specimen delineated in fig. 7, in one part of which both these
tissues are seen as there represented, thus enabling me to iden-
tify the inner protoplasmic membranes (7 c) of the one with the -
only membranes seen (17 c) in the other. Numerous similar
specimens have since confirmed the correctness of this explana-
tion, which clears up many obscure points. I now find no
difficulty in recognising the two structures; the protoplasmic
membrane, whether seen in front or in profile, is always more
granular, from the adhesion to its inner surface of some
of the granular elements of the protoplasm, than is the case
with the cell-membrane, the outlines of which are invariably
clear and fine. Fig. 8 represents three cells from the same
specimen as fig. 7, in which the protoplasmic membranes
nearly fill the respective cells; such specimens, seen in
section, exhibit the appearance of the centre cell of fig. 15.

I conclude that if we could bring all these structures into
view in a section of aliving Volvox, they would present the
appearance of fig. 12, where a represents the cell-membranes,
b the protoplasm and its contiguous membranes, d the
common pellicle, and e the prolonged threads of the proto-

Witiamson on Volvox globator. 5f

plasm connecting it with the peripheral walls of its cell.
Such a section however cannot be obtained until chemical
re-agents have rendered the tissues rigid, which process alters
their arrangement and aspects.

The entire thickness of the cellular peripheral wall of the
Volvox is about 1-1400th of an inch, in specimens that have
been a few days mounted in glycerine. The superficial dia-
meter of the cells in the living Volvox varies from 1-800th to
1-]000th of an inch.

The next question relates to the nature of the threads that
connect together the protoplasms of the two varieties of
Volvox. These cannot be exactly the same in figs. 1 and 10. In
fig. 1, the entire protoplasmic mass is drawn out into a stellate
form. Each thread consists of the protoplasmic membrane,
and a portion of its contents. In fig. 10, on the other hand, the
threads contain little or none of the protoplasmic granules,
but appear to consist solely of a portion of the membrane.
Of course to produce such a result this membrane must be highly
ductile, and consequently but partially organized. That the
threads are ductile and capable of being drawn out is easily
seen on compressing a Volvox between two glasses. The fluid
distending the sphere is very viscid and probably consists of
mucilage. ‘This must have been secreted by the protoplasms.
When we remember that cellulose is but a modified form of
gum, we ean’ readily conceive that the conversion of the one
into the other may sometimes be imperfectly accomplished
amongst these lower forms of vegetation. Such I believe
to be the explanation of the ductility of the protoplasmic
membrane, and of the threads into which it is drawn out.

Fig. 16 throws a little additional light on this subject. We
see from it that whilst the thread sometimes consists of the
drawn-out membrane (16 a), at others the membrane has re-
ceded from the outer cell-wall, leaving only a very faint line,
thickened at its peripheral extremity, marking the former
point of junction with the outer cell-wall. The same thing is
seen in fig. 7. In both these examples the threads were ori-
ginally of the stellate type seen in fig. 1. Whilst the points of
contact with the outer cell-wall are still indicated, they have
lost their irregular dichotomous character, and are reduced
to straight, radiating, capillary threads, such as are seen in
fig. 1. ‘The greater portion of the viscid membrane has receded
towards the protoplasm, whilst a small part has in like manner
accumulated at the point of attachment to the cell-wall, form-
ing the peripheral dots seen in the above figures; similar
appearances present themselves in the other variety, fig. 10.
Near the centre of fig. 11, the threads uniting’ several of the

52 Wi iiamson on Volvox globator.

protoplasms have become broken; those which remain have
drawn their respective protoplasms towards the sides of the
cells to which they are attached. All these circumstances in-
dicate a degree of ductility in the protoplasmic membrane
such as would scarcely exist supposing it to consist of per-
fectly organized cellulose.

In the young gemma, as already observed, the protoplasms
are in close contact on all their sides ; but a is only at a few
points that an actual junction is established corresponding
with the extremities of the future threads. What has been
the eclectic power leading to this result? It is not mere acci-
dent. Reference to fig. 11 will show, that in passing from one
_ protoplasm to another these threads always traverse the sides
of the hexagonal cells, and never their angles. It is also ob-
vious that these points of adhesion are chosen prior to the de-
velopment of the outer cell-membrane. This is indicated by the
unvarying continuity of the threads when they are single ; but
still more so when they are double and treble, as is frequently
the case (figs. 10 and lle, e'). Whatever the number pro-
ceeding from a protoplasm to any one side of its cell, the same
number proceeds to the proximate side of the adjoining cell:
I have scarcely seen one exception to this rule. I think the
explanation just given meets the case ; if so, it may be a ques-
tion whether the cell-membrane is developed between the con-
tiguous extremities of the two protoplasmic threads, or whether
it is deficient there, admitting of an actual as well as an appa-
rent continuity. I have already given one or two reasons for
believing the former hypothesis; but even should the -latter
prove the true one, we shall only have recurring in Volvox a
phenomenon that is common enough amongst the perforated
cells and ducts of the higher plants. In but one instance have
I seen a specimen countenancing the latter idea. In it the
peripheral layer of cells was very thin and compressed ; many
of the cells appeared to be wholly detached from each other, as
represented in fig. 9; nevertheless the threads proceeded from
protoplasm to protoplasm, apparently traversing the intercel-
lular spaces. This specimen is so entirely exceptional as to leave
little doubt on my mind that is capable of being explained.
I have no doubt that, owing to the thinness of the peripheral
cells,a section of it would resemble fig. 13. If we suppose that
the circumstances which render the majority of Volvox cells
hyaline and invisible, still continue to affect the portions of
those in question that are external to the dotted line 13 f,
the remainder being visible, we should have precisely such an
appearance as is presented in fig. 9; the only visible por-

Witutamson on Volvox globator. 53

tions of the cells being those which were below the points of
mutual contact.

The direction taken by these threads frequently demonstrates
the presence of invisible cell-walls midway between two pro-
toplasms. We have already seen that when the threads are
liberated their tendency is to become shortened ; hence they
pursue the most direct course from one point to another. But
we occasionally see examples of what is delineated in fig. 10 e’,
where two threads run parallel for some distance and then
suddenly diverge, proceeding to different protoplasms. This
condition obviously indicates the existence of some invisible
point dapput, where the divarication occurs. This, doubt-
less, consists of the hyaline cell-wall. We obtain similar evi-
dence from almost every example of Volvox, when we examine
the protoplasms at one margin of the sphere in profile. This
can readily be done with object-glasses of short focus, owing
to the transparency of the tissues. We very frequently see
that the threads, instead of being straight, dip inwards towards
the centre of the sphere, and meet at a well-defined angle mid-
way between the two protoplasms, as represented in fig. 12 e.
This can only be explained in the way just suggested.

Whatever may be the true nature of the objects which I re-
gard as cells, they are obviously separated from the protoplasms
before the latter assume their stellate forms, or develop their
delicate connecting threads. I have had specimens of every
age, from the gemma artificially liberated from the parent
sphere, to the hyaline and matured individual, in all of which
these cells exist. They are obviously developed immediately
after the final process of segmentation has completed the re-
quired number of protoplasms ; the development of these cells
of the cilia and of the common pellicle apparently taking place
about the same time. Names sometimes matter little; but
here they are significant, since they involve the origin of the
disputed structure. Mr. Busk regards it as the outer covering
of the protoplasm dropsically distended; I believe that the
outer covering (my protoplasmic membrane) remains in close
connexion with the viscous protoplasm until the two are sepa-
rated artificially, and that the cell is a secretion from the outer
surface of the protoplasmic membrane. According to this ex-
planation, the two bear the same mutual relations as exist
between the outer and inner membranes of any other Confervoid
cell. The beautiful stellate, spiral, and other forms which the
inner membranes of many of these plants assume after their
separation from the cell-wall, with which they were primarily
in close contact, afford ready illustrations of the similar trans-
formations in Volvox.

54 Wittramson on Volvox globator.

The origin of the superficial pellicle (fig. 14d and 15 d)-
remains to be considered. In my last memoir, I stated that
each young gemma was developed within a large transparent
vesicle (fig. 5 f and 6 f), which appeared to be the expanded
cell-wall of the primary cell (a). My more recent investigations
confirm this conclusion. When we detach a young gemma and
its vesicle from the parent Volvox, the vesicle usually carries
away with it a few of the contiguous protoplasms adhering to
its outer surface (fig. 6 5), indicating the firm adhesion between
this vesicle and the walls of the sphere, which we know to
exist. This vesicle expands as the gemma increases in size.
At first, the latter is closely invested by the former; but when
the cilia are developed on the surface of the young organism,
the vesicle becomes considerably distended, allowing the
gemma to revolve freely within its prison house. (See fig. 5.)
At this time the gemma is already invested by its proper
superficial pellicle ; hence the latter cannot be the modified
primary germ-cell, as supposed by Mr. Busk, but is a new
growth developed on the surface of the gemma whilst enclosed
within the enlarged germ-cell. The source of this pellicle must
be sought for in the aggregated protoplasms. It appears to be
an independent secretion thrown off by them, in the way that
the epidermal celis of a leaf co-operate to produce the similar
structureless superficial pellicle. If this be a true homology,
it would countenance the opinions of Schleiden and Payen,
rather than of Mohl and Henfrey, the latter of whom regards
the superficial pellicle as composed of the altered primary
walls of pre-existing cells, and not as an external secretion.
Henfrey’s explanation is that which I applied to the pellicle
of Volvox, until the suggestion of Mr. Busk, respecting the
primary condition of the volvocine protoplasms, showed me
that in this instance the hypothesis was untenable.

The relative periods at which the cells, the superficial
pellicle, and the cilia make their appearance is not easily
determined. So far as I have been able to form an
opinion, I am disposed to think that the cilia first make their
appearance, the cells and the outer pellicle being subsequent
growths. A priori, we should have expected this to be the
case, since it would not have been easy for delicate, flexible
cilia to force their way through one or two imperforate invest-
ing membranes. When the cilia are first produced they are
very short, but they gradually lengthen, apparently by addi-
tions to the base of each, secreted by the respective proto-
plasms. After their formation we can readily understand how
the pellicle could be secreted from the mass of protoplasms
between and round the roots of these cilia, no pellicle being

Wiiiamson on Volvox globator. : a}4)

produced where they were attached to the protoplasm. As
subsequent additions were made to their length, they would
readily push through the apertures so left. After the cilia
have fallen off, these apertures can occasionally be seen .
arranged in pairs, as described in my last memoir. [I have, in
my cabinet, one specimen in which two large Infusorize have
been developed within the Volvox, and have apparently eaten
away many of the protoplasms without destroying the integrity
of the sphere: the cilia have also fallen off: the remaining
membranes confirm my previous description of the appearance
and relative positions of these apertures.

The fluid with which the sphere is filled is not mere water,
but is apparently mucilage. In a preparation in which a
number of these objects are mounted in dilute alcohol, this
gummy matter has changed to a brown colour, and refused to
mingle with the alcohol, as would be the case supposing it to
be mucilaginous. This proves that it is a true secretion from
the organism, and not merely water absorbed by endosmosis.
We may possibly obtain from this source an explanation of
the distension of the entire sphere, of the individual cells, and
of the vesicles investing the germs. As this gummy secretion
increased in quantity, each thin membrane investing the
respective protoplasms from which the fluid was derived, would
become distended for its reception, as the mere result of internal
centrifugal pressure. The secretion itself is, perhaps, little
more than a diluted condition of the same gum as that which
is more or less completely converted into cellulose in the
various investing membranes just enumerated.

I cannot but think that the details now brought forward,
resulting from a careful re-examination of the entire subject,
will convince every unbiassed observer of the general accuracy
of my previous conclusions, and especially those relating to the
cellular structure of the walls of the sphere. In the memoir in
which these conclusions were recorded, I pointed out the close
analogy that existed between the development of Volvox and
that of many of the lower Alge and Conferve. I also referred
to the obvious resemblance of each protoplasm to the well-
known Zoospores.

It is only whilst the segmentation of the gemme is in
progress that a real relation exists between Volvox and young
growing Conferve. At a later peried every segment ofthe
former becomes converted into a Zoospore: each Zoospore,
in turn, having the power to cast off its cilia, and go through
a new process of segmentation, in precisely the same way as
the Zoospores of a Conferva or a Vaucheria. Only a few in
each Volvox are selected for this purpose, but the potentiality

56 Wiuamson on Volvox globator.

doubtless resides in all. The cell-walls in the Volvox re-
semble the cells in which the Confervoid Zoospores are deve-
loped, the only essential difference being, that in the former
instance the cilia penetrate the cell-wall, instead of being
retained within it, and the germination is carried on whilst
the Zoospores maintain their connexion with the ane
sphere, instead of being previously detached from it.

All the facts brought to light by this inquiry confirm my
previous conclusion (which conclusion receives, also, the
effective support of Mr. Busk), that the affinities of Volvox
are with the vegetable, and not with the animal kingdom.

Since the above memoir was laid before the Society, Mr. Busk has
supplied me with specimens of Volvo stellatus. I quite agree with him -
in his view that V. stellatus, V. globator, and V. aureus are mere varieties
of one species. In his specimens of V. stellatus the protoplasms were of
the stellate form of fig. 1. The investing cells were obviously present in
all the examples which I ecamined. The above generalisation by Mr. Busk
does away with the possibility of the brilliant granules of the protoplasm
being spores, and leads to the probability that the curious bodies either
in V, stellatus or V. awreus are the true winter spores. In J. stellatus I
have noticed that the ordinary power of gemmation appears to have worn
itself out; since, though the gemmez often co-exist with the spores (7),
they are small, colourless, and abortive. The curious stellate invest-
ments of the spores (?) of V. stellatus appear to me to be homologous
with my vesicles (fig. 5), within which the true gemma are developed,
and consequently to be the modified primary germ-cells. These often exist
without the stellate protuberances, when their resemblance to the vesicles
of the gemme is very obvious. In the pond from which I chiefly obtained
my specimens this year, they were all of the type represented in fig. 10.
This was their character in April. In the beginning of September, all
traces of the connecting threads had disappeared, each protoplasm then
resembling my fig. 4. At the close of September nearly all the Volvoces
disappeared. In the few that remained, the protoplasms had reverted to
the stellate type of fig. 1.

Oh Biber)

On the Application of Puorocrarny to the Representation of
Microscopic Objects. By JosErpu Dertves, Esq. Commu-
nicated by Mr. Bowerbank. (Read Oct. 27, 1852.)

At the present time, when the microscope is contributing
valuable aid in nearly every department of science, and its
uses as an instrument are more generally known, it becomes of
the greatest importance to possess some method more truthful
than those hitherto adopted for copying the beautiful images
of the achromatic object-glass.

The recent discoveries in photography render its appli-
cation to the microscope a subject for much consideration,
since only by its assistance can we hope to obtain trustworthy
impressions of objects so delicate and minute. I would, there-
fore, beg to submit to the consideration of the Society the
method I have adopted for producig these copies; and as
an illustration of the successful application of Photography to
the microscope, I have the honour of presenting the specimens
which I have recently obtained.

I must, however, beg to state that others have an earlier
claim than myself to this application; but with so little
success had it previously been carried out, that I believe I
am correct in saying it has been generally abandoned as a
means of depicting microscopic objects. But for the satis-
factory result it is only necessary to refer to plate VII.

The only arrangement necessary for the purpose is the
addition to the microscope of a dark chamber, similar to that
of the camera obscura, having at one end an aperture for the
insertion of the eye-piece end of the compound body, and at
the other a groove for carrying the ground-glass plate.

This dark chamber should not exceed 24 inches in length
(the size which I have found best to adopt): if extended
beyond this, the pencil of light transmitted by the object-
glass is diffused over too large a surface, and a faint and
unsatisfactory picture is the result. The specimens ex-
hibited were taken at this distance, which has the additional
advantage of producing a picture, in size very nearly equal to
the object as seen in the microscope. The eye-piece must be
removed from the compound body, and the object (being well
illuminated by reflection from the concave mirror) must be
adjusted and focused upon the ground-glass plate. In the
production of positive pictures a slight difficulty here arises,
dependent upon the “ over-correction” of the object-glass.
The effect of this ‘“ over-correction” is to project the blue
rays of light beyond the other rays of the spectrum, and as
the chemical properties of light reside in the violet and blue

VOL. I. ia

Seemann ee essai,

58 On the Application of Photography.

rays, it becomes necessary that the plane of the sensitive
plate should coincide with the foci of these rays, and it must
therefore be placed beyond the surface at which the best
definition is seen; this amounts to some distance with the
lower combinations, and decreases with the increase of mag-
nifying power.

For the production of negative pictures the ordinary illu-
mination is not sufficient, and recourse must be had to the
sunbeam, which should be reflected upon the object by the

plane mirror when powers are used not exceeding the quarter

of an inch combination. It is not necessary here (when pro-
ducing negatives by the sunbeam) to allow for the “ over-
correction” of the object-glass, but merely to focus the object
carefully upon the ground-glass plate.

With regard to the time required for the production of
these photographs, unfortunately no precise rules can be
given, since it must vary with the sensitiveness of the mate-
rials‘employed. The larger group exhibited was produced
by the “1 inch object-glass,” and the time given varied from
ten seconds to one minute. The smaller group, representing
““scales of Lepisma saccharina by the quarter inch and one-
eight inch glasses, was taken with a more sensitive collodion ;
and the time from ten to fifteen seconds.”

In the production of negative pictures (from which the
paper specimens were obtained) a moment’s exposure to the
sunbeam is sufficient when using the lowest powers, and with
the highest I have varied the time from five to ten seconds.

In conclusion, | beg to submit this method which I have
found so simple and successful, in the hope that the com-
munication may be the means of directing attention to a subject
both useful and interesting, and in the confidence that most
satisfactory results will yet be obtained.

Some Observations on the Structure of the Starch-Granule. By
Geo. Busx, Esq., F.R.S. (Read Dec. 29, 1852.)

“‘ No substance has been more investigated, and yet of which
there is less known, than starch. After the researches of ten
years, in the course of which the most various views have been
propounded on the nature of starch, and after all its character-
istics as a proximate vegetable substance have been discussed,
we are little or nothing in advance of the old point of view ; and
although we may, perhaps, not be wholly without some addition
toour knowledge in secondary points, we are still entirely without
any sound reasons to suppose that we have arrived at the truth.”

This passage, from Poggendorff’s Annal., 1837, vol. xxxii.

Busk on Starch-Granules. : 59

is quoted by Professor Schleiden, writing eight years after-
wards,* and he adds that these eight years, notwithstanding the
publication of innumerable works by chemists and vegetable
physiologists, had been equally thrown away in the investi-
gation of this important vegetable element; but, strangely
enough, asserting that this unsatisfactory result had arisen
solely in consequence of neglect, or from superficial micro-
scopic examinations.

If our knowledge respecting the structure of the starch-grain
were thus unsatisfactory in 1844, it can scarcely be said to
have been much enlarged since, notwithstanding the investiga-
tions of the learned and eminent Professor himself; and to
which investigations—whatever he may be inclined to think or
express with respect to the labours of others—he would not be
the last to resent the imputation of superficiality.

We cannot but believe that a subject, which has thus baffled
the endeavours of so many and such competent inquirers, must
- possess some inherent difficulty, for, in 1851, we find Dr. A.
Braun,{ one of the most accurate and acute of recent vegetable
physiologists, still lamenting, in the same terms as Schleiden, the
want of accurate knowledge on the subject of the origin, forma-
tion, and structure of starch, which he is of opinion demands a
new and careful investigation, seeing that none of the views
set up are sufficiently based upon direct observation. :

Having lately been incidentally led to the investigation of
the structure of the starch-granule, I have thought the results
might be interesting to the Society, although they cannot be
said to be altogether novel.

In the numerous and very different modes in which it has
been attempted to explain the structure of the starch-granule,
only two really and essentially distinct views seem to be ex-
pressed. ‘These views,” as Schleiden observes, “are de-
cidedly opposed to each other, and on the assumption or rejec-
tion of them, the chemical judgment passed upon this substance
must essentially depend.”

1. According to the one view the starch-granule is a vesicular
body, the wall of which differs, at all events in consistence, if
not in chemical constitution from the contents.

2. In the other view the granule is considered as a solid
body, constituted either of a homogeneous substance, or com-
posed of concentric layers, deposited, according to one set of
observers, around a nucleus, either differing in its chemical

* ‘Principles of Scientific Botany.’ Translated by Dr. Lankester.
1849. p. 19.
+ ‘Betrachtungen iib, d. Erscheinung der Verjiivgung in der Natur.’

1851.
F 2

60 Busx on Starch-Granules.

nature from the layers around it (Fritsche), or not essentially
different in that respect (Endlicher and Unger). Schleiden,
on the other hand, and many other observers, look upon the
supposed nucleus as a minute cavity or indentation. Dr. A.
Braun (/. c.), however, supposes that this cavity does not exist
originally in the granule, but that it is of a secondary nature,
arising in the disappearance of the nucleus.

The laminated, or supposed laminated, appearance evident
in many forms of starch, and demonstrable perhaps in many
others by means of polarized light, has been variously explained
according to the above views not" the essential constitution of
the sranules.

In accordance with the former of these views, Miunter,*
Nageli,t and Link, suppose that the lamine are formed by an
internal or centripetal deposition of matter in the interior of
the cell, and, according to the latter, this deposition is con-
ceived to take place from without, or, as it may be expressed,
centrifugally. This notion appears to be that more generally
adopted. Originally propounded by Fritsche, it is followed
by Schleiden, and, more recently also, though with some hesi-
tation, by Dr. A. Braun (2. c.) who considers it as much more
probable than that advocated by Munter and Nageli, if the
starch-grains are not themselves cells, but merely the product
of secretion from the cell-contents, in the same way as the cell-
membrane is, with which the starch is so closely allied. ‘The
same view is also adopted by Focket and Schacht.§

The above is a very brief and imperfect summary of the
views more generally entertained on the structure of starch,
and, omitting all reference to what has been written respecting
its mode of “origin (which, in fact, amounts to little) and its
use in the vegetable economy, I will now proceed to notice
what may be termed a modification of the former of the above
described views, or of that which assigns a cellular structure
- to the starch-granule, and the reception of which I am greatly
inclined, from my own observations, to advocate. 3

Leeuwenhoeck,|| to whom we are indebted for the earliest
notice of starch-granules, enters with considerable minuteness
into a description of those of several plants, such as wheat,
barley, rye, oats, peas, beans, kidney beans, buckwheat, maize,
and rice, and very distinctly describes experiments made by

* Minter, ‘Ub. das Amylon der Gloriosa superba,’ &c. (‘ Bot. Zeit.’
1845, p. 198.)

{ Nageli, ‘ Zeitschrift.” 1847, p. 117.

+ Focke, ‘ Die Krankheit der Kartoffeln.’ Taf. ii. fig. 13, f. g. h.

§ Schacht, ‘ Die Pflanzenzelle.? 1852, p. 41.

|| Leeuwenhoeck, ‘ Epistole Physiologice,’ &c. Delphis. 1719, p. 236.

Busx on Starch-Granules. : 61

him in order to investigate the structure of the starch-granule,
He placed a certain. number of the grains upon a clean piece
of glass, and added a minute drop of water, and, upon the
grains thus separated from each other, he placed two more
drops of water. The water was then dissipated by the apph-
cation of heat for about a minute. He then noticed that the
-starch-granules had lost their rotundity and degenerated into
plane figures of unequal size. From this experiment he con-
cluded that the starch-grains of wheat, and other plants
examined by him, were covered, like the wheat-grains them-
selves, by a cuticle. And he imagined that the incurvation
of the starch-granule took place at that part only, where the
cuticle, not being continuous, was joined by a sort of com-
missure—whence, he conceived it arose, that the granules,
being heated and moistened, dehisced, and sank down into a
flat form. He gives numerous figures of various sorts of
starch in different stages, from partial expansion to complete
evolution.

We have here apparently the basis of the cellular hypothesis
of starch, afterwards more fully developed by Raspail and
others. Leeuwenhoeck, however, does not appear to have re-
garded the contents of the starch-cell as fluid; and in this he
was obviously more correct than his modern followers. But
as Raspail’s view, in its integrity, is no longer maintained, I
believe, by any one, having been long ago given up even by
his more immediate followers, and particularly by Payen and
Persoz, it is needless further to advert to it. The later modi-
fication also of it advocated by Minter and Nageli, though '
with more scientific pretensions, is still so diametrically
opposed to what may perhaps now be considered the correct
doctrine of vegetable cell-formation, as in my opinion to be
totally inadmissible.

Following in the footsteps of Leeuwenhoeck, Dr. S. Reissek*
attempts to deduce the cell-nature of the amylum-granules
from the phenomena presented during their decay or disso-
lution, when left for some time in water. He says that, “‘ owing
to the solution and exosmosis of their internal and more solid
substance (in contradiction to Schleiden and Miinter), they
become hollow, so that of the entire starch-granule only the
outermost layer remains, which, having become soft and
flexible, assumes the appearance of a closed sacculus, that is,
of a cell.” He therefore regards the amylum-granule as a
perfect cell.

* Keissek, Haidinger’s ‘ Berichten tb. d. Mittheil. von Freunden d.
Naturwissen. in Wien.” Mai—Oct. 1846. Wien, 1847, p. 84.

62 Busk on Starch-Granules. :

M. Guibourt * says that the internal portion of the starch-
grain breaks up in the form of flocculi, whilst the outer
portion, the membrane, is lacerable, and occasionally exhibits
the form of an empty pouch.

The expansion and alteration in form of the starch-grain,
under the influence of heat and of sulphuric acid and other
re-agents, is a fact recognised also by Schleiden and those who
adopt the view of its solid or homogeneous nature; it is, in
fact, so obvious a phenomenon that it could not possibly
escape observation. ‘They, however, and I believe nearly all
who have adopted the cellular hypothesis, consider this to be
owing simply to the expansion of the solid body or vesicle.
Till very recently, Leeuwenhoeck only appears to have attri-
buted this increase in size and change of form of the granule,
not to a mere expansion, but to an opening out of the granule
on one side, or to its evolution in other words, whence it
assumes a flattened figure, and of course an increase in
apparent diameter. Although not, in the precise sense,
understood by Leeuwenhoeck, I believe that his notion, with
some correction, represents more nearly the true doctrine of
the structure of the starch-granule than that of any of his
successors till a very recent period. |

In the Philosophical Magazine for April last is a paper
‘On the Amylum Grains of the Potato,’ by A. G. C. Martin,
Librarian of the Imperial Polytechnic Institute of Vienna,
which appears to me to contain the germs at all events of a
correct doctrine with respect to starch ; and as I was led to
pretty nearly the same conclusions as himself, though from
experiments of a different kind and instituted for a different
purpose, I have the more confidence in his results. And as
the procedure I was led, more accidentally than otherwise, to
adopt is perfectly easy and simple, this paper may at all
events serve to incite others to repeat the experiments, and
thus we may hope that the verata questio of the structure of
starch may in some degree be set at rest. M. Martin’s mode
of experimenting is nearly as possible the same as that
adopted by the illustrious Leeuwenhoeck, and his results are
not in the main very dissimilar.

As the observed results at which M. Martin and myself have
arrived in the examination of potato starch appear to coincide
in every particular, it is obvious that the reasoning applied
to his is equally applicable to mine. These results have in
both cases been arrived at by noticing the phenomena which
take place in the amylum-granule during its expansion, and

* “Journal de Pharmacie.’ 1846, p. 191.

Busx on Starch-Granules. 63

not when it has nearly or completely terminated.* This ex-
pansion or dissection of the granule is effected by M. Martin
by means of heat applied in an ingenious but still incon-
venient way, while the object is under the microscope. He
thus employs it :—

“ Between two very thin glasses, of the same size as the
stage of the microscope, a little amylum, with a sufficient
quantity of water, is to be put, and the former well spread out
with the finger, to prevent as much as possible the formation
of bubbles. The number of amylum grains in the field of
view should not exceed ten or fifteen. The glasses should
lie freely on the spring-piece, which must be raised by means
of two pieces of cork introduced below it, so that while the
two glasses are lying right upon the object-bearer, a current of
cold air will ascend from below, or permit the little flame to
continue burning in the hole of or below the stage. As the
glasses are wide, they protect the microscope from too great a
heat or other danger. The small flame is to be obtained from
a common thread, doubled and slightly waxed. ‘This, when
ignited, gives a flame quite sufficient to boil the amylum.”

In the course of his experiments he discovered that the
slightly iodizing of the starch-grains delayed, so to speak, the
entire process of boiling, and rendered the result more certain
and satisfactory, and he states that his process seems to succeed
still better in a concentrated solution of alum, with as much
tincture of iodine as will colour the grains of a steel blue.

The same benefit arises also in my process from the addition
of as much iodine as will render the starch a pale blue without
destroying its transparency ; and the use of iodine in either
case is attended with the further advantage that it renders the
starch in its subsequently changed condition much more visible
than it otherwise would be.

Instead of heat I employ concentrated sulphuric acid, and in
the following way :—A small quantity’-of the starch to be
examined is placed upon a slip of glass and covered with five
or six drops of water, in which it is well stirred about, and
with the point of a slender glass rod the smallest possible
quantity of solution of iodine is applied, which is to be quickly
and well mixed with the starch and water. As much of the
latter as may be must be allowed to drain off, leaving the
moistened starch behind, or a portion of it is to be removed by
inclination of the glass, and the starch is then to be covered with
a piece of thin glass. ‘The object must then be placed in the

* Vide Observations on the Structure of the Starch-granule in a paper
on Valisneria spiralis, by E. J. Quekett, published in the third number
of the ‘ London Physiological Journal’ in 1844.

64 Busx on Starch-Granules.

microscope, and the object-glass i or $) brought to a focus
close to the upper edge of the piece of thin glass, With a
slender glass rod, a small drop of strong sulphuric acid is to be
carefully placed immediately upon, or rather above the edge
of the cover; care being taken that it does not run over it.
The acid of course quickly insinuates itself between the glasses,
and its course may be traced by the rapid change in the
appearance of the starch-granules with which it comes in con-
tact. The course of the acid is to be followed by moving the
object upwards, and when, from its diffusion, the re-agent
begins to act more slowly, the peculiar changes in the starch-
granules, now also less rapid, may be readily witnessed.

These changes in potato-starch are thus described by M.
Martin.* “First, the amylum grain sinks in, in that place,
where, according to Fritsche, the kernel (nucleus) is situated.
On the surface minute fissures appear, two of which almost
regularly diverge towards the thicker end of the grain. The
grain continues to be depressed inwards until a cavity is
formed which is surrounded by an elevated ridge. In pro-
portion as the grain swells up, this ridge increases in circum-
ference and decreases in breadth, that is, continues to get
flatter until fissures, mostly of a stellated form, appear in the
hitherto, little altered thicker part of the grain. ‘The process
is not very rapidly developed, and it is very difficult for the
eye to follow it. Suddenly something is torn off, the grain
is extended lengthways, and in the next moment a wrinkled
skin of a rounded, generally oval shape, lies on the glass.
Middle sized and sina grains exhibit this shape most dis-
tinctly ; and they have usually only one longitudinal wrinkle,
the upper and lower ends of which are pointed. The constant
appearance of this wrinkle is important for the development
of my theory. The appearance of this disc,’ he goes on to
say, ‘‘ demonstrates that it is perfectly flat, and has a slightly
elevated edge which also becomes flat on pressure. The con-
tour is rounded, but perfectly sharp. If the two glasses be
violently moved from one side to the other whilst pressing
the amylum, the disc is torn, and it is distinctly seen, especially
in the blue-coloured ones, to consist of two layers, an upper
and a lower one. Further examination shows that they are
collapsed vesicular bodies, consisting of an extremely fine but
strong and elastic membrane.”

‘‘The primary form, therefore, of the amylum grain,” ac-
cording to M. Martin, ‘is aspherical or ovate vesicle. If
this be considered as empty, and so contracted that one-half

Pe. 2K,

Busx on Starch-Granules. | 65 |

lies in the other half, a watch-glass shaped basin is formed,
which after boiling and pressure between the two glasses,
appears, in consequence of the delicacy and elasticity of the
membrane, as a flat, round-edged disc.” ;

According to him, it follows, that the starch-granule, in its
more usual form at least, is formed by the inrolling upon itself
of this spherical or ovate vesicle. It is not very easy, at all
events I do not find it so, to comprehend M. Martin’s expla-
nation of the mode in which this inrolling or involution takes
place, nor have my own observations as yet enabled me to
express a very decided opinion with respect to this point.
The appearances exhibited in the microscope, under the action
of strong sulphuric acid, convey the idea rather of an unfolding
of plaits or ruge, which have, as it were, in some kinds of
starch (those with a long fissure-like or stellate hilum
especially) been tucked in towards the centre of the starch
grain, than of the unwinding of rolls. And I conceive that
the apparent laminz are nothing more than the indications of
the edges of such plicz or folds in the contracted state, upon
which I shall say a few words presently. ‘The starch-grain
of the horse-chestnut perhaps affords as good an example as
any, and one readily obtainable, of the appearances which
might be supposed to arise were the constitution of the granule
such asI have just described ; that is, as far as the tucking in of
the vesicle towards the centre is concerned, because in this grain
I am not aware that the concentrically laminated appearance
arising from folds of the vesicle is evident. Fig. 10, Pl. VIII,
represents the usual forms and aspect of the unaltered starch
of this fruit, and figs. 11, 12, 13, various granules in different
stages of evolution under the use of strong sulphuric acid.

If it be allowed that the starch-vesicle, as the ultimate
product of the evolution of the grain might perhaps be
termed, be elastic—which, in all probability, it is—it is
easy to understand, as in fact is pointed out by M. Martin,
that the portions which are folded into the interior must be
more or less compressed, and thence denser ; 1n consequence
of which inequality of tension the phenomena exhibited
under polarised light might be explained. I have examined
several varieties of starch, such, for instance, as of the Po-
tato; the Arrow-root termed ‘Tous les mois,” which is, I
believe, afforded by a species of Canna; two other kinds of
arrow-root ; the starch of the Spanish Chestnut; of the Yam ;
of aspecies of Curcuma, which seems to be identical with East
Indian arrow-root; of Cycas circinalis; Zamia integrifolia ;
Arum maculatum, and what is termed Tacca arrow-root; and
find more or less distinctly in all, indications of a similar

66 Busx on Starch-Granules.

structure, differently modified, however, in some respects, in
each. Upon referring, moreover, to the figures of different
kinds of starch given in Schleiden’s ‘ Botany,’ before quoted,
a tolerably complete series of development, as it may be
termed, of different forms of starch, will, I think, be suffi-
ciently obvious. Fig. 13 of Schleiden, representing starch-
grains from the rhizome of Anatherum iwarancusa,* and fig.
those of Iris pallida, show, as I conceive, the simplest form of
inversion or folding of the edges of the starch-vesicle. A
further stage is apparent in fig. 12, the starch of Colchicum
autumnale; and a further advance may be traced in fig. 14,
the starch-granules of Arum maculatum, whence the tran-
sition to the form presented by the starch of the horse-
chesnut is sufficiently clear, and from these more or less open
forms to the complete involution seen in the potato-starch, &c.

The dissection of the starch-grain may be effected in several
ways besides those I have noticed, and equally, if not more,
conveniently. And as the dissection effected in any of these
modes appears to yield the same result, the latter may be
regarded perhaps as the more worthy of confidence.

I have usually selected for my experiments the form of
arrow-root called ‘‘Tous les mois.” It is a favourable subject
for investigation, owing to its large size and regular con-
formation, as seen in figs. 1, 2, 3, 4,5. The grains of Tous
les mois are of various sizes and of different shapes,—some
oval, some more expanded, with a sort of horn or shoulder on.
each side, or on one side only. The grains, like those of most.
kinds of starch, are not cylindrical, but flattened, and towards
one end of each grain is a minute circular spot, the area of
which appears granular; and concentric to this spot the
surface of the grain—or rather one of the flat surfaces only
and the sides—is marked with delicate concentric rings.
It is these rings which have been described as indicating
a laminated structure, and, consequently, corresponding lines
or planes should be seen, under favourable circumstances,
passing through the substance. This appearance has actually
been described as existing by Schleiden and others, but I have
looked for it in vain, and Mr. Quekett, in his Lectures on
Histology, describes the markings as superficial. His ex-
pressions, moreover, would plainly imply that this accurate
observer entertains an opinion with respect to the structure of
the starch-grain pretty nearly if not quite identical with that
advocated in this paper, and that, as I suppose, the lines
indicate the ruge or folds into which the starch-vesicle is

* Miinter, however, denies the existence of starch-granules like those
figured by Schleiden in the rhizome of A. wwarancusa.

Busx on Starch-Granules. 67

thrown in the contracted state, and that this is the case seems
to be shown by the immediate effects of re-agents. The first
change, after a slight swelling of the starch-grain, consists in
the appearance of minute transparent elevations around the
edge of the grain, as shown in fig. 6, each of which, I con-
ceive, represents the edge of a fold or ruga ; a further stage of
expansion is shown in fig. 7, and a still farther one in fig.
8; whilst the full expansion of the vesicle in Tous les mois
is shown in fig. 9. I believe, also—but of this I would speak
very doubtfully — that each starch-vesicle has an opening
which corresponds with the central spot or hilum. With
respect to the contents of the vesicle, some appearances lead
me to suppose that, occasionally at all events, it contains a
flocculent or grumous material—amorphous starch, which is
equally coloured by iodine, as is the wall itself of the vesicle.
There is sometimes also an appearance of a transparent
colourless wall around these grumous contents, in a form of
arrow-root I have examined; but an outline of this kind is
often a very deceptive phenomenon, and I do not wish to be
understood positively to assert its existence even in the case
alluded to.

Two additional modes, which I have found convenient in
the examination of starch, consist:—Ist. In the previous
roasting of the grain till it acquires a light-brown colour, and
is, in fact, converted into British gum; while in this state,
if it be moistened with a very weak solution of iodine, the
grain gradually unfolds itself in the most beautiful manner.
2. The iodized solution of chloride of zinc, proposed by Pro-
fessor Schultz, may also be very advantageously employed.
This solution, if quite concentrated, does not at first colour
the- starch at all, but, on the addition of a little water, the
blue colour is elicited, and the starch-graims gradually swell
out and evolve themselves in the same way as they do under
the previously described treatment. I make the iodized so-
lution of chloride of zinc by dissolving 1 ounce of fused
chloride of zinc in about half an ounce of water, and adding
to the solution (which amounts to about an ounce fluid mea-
sure) 3 grains of iodine dissolved, with the aid of 6 grains
of iodide of potassium, in the smallest possible quantity of
water.

Since the above paper was read, I have noticed appear-
ances in the amylaceous corpuscles which occur in the wall
of the primordial utricle of Hydrodictyon utriculatum, which
lead to the opinion that the starch—in this case at least,

68 Smitu on Asteridia.

and probably in all the similar forms and situations in which
it occurs in the lower Conferve, &c.—is deposited around a
nitrogenous nucleus. In Hydrodictyon the fact is very clear,
that the central portion of the amylon-corpuscle is turned of
a deep brown by iodine, or pink, by sulphuric acid and sugar
(as was first pointed out to me by Mr. Huxley), and that at
one time it exhibits no trace of starch in its composition, but
that subsequently this nitrogenous nucleus becomes sur-
rounded, not with an entire wall of starch, but apparently by
a cup-shaped deposit of that substance in which the nucleus
les imbedded, or from which it projects on the external
aspect. Further observation of this and analogous pheno-
mena may perhaps in time lead to a more satisfactory ex-
planation of the genesis of starch than can at present
possibly be given. It does not, at all events, contradict the
notion of the vesicular nature of the starch-grain, but rather,
as it seems to me, tends to confirm it; for we have only to
imagine the entire removal—as we may often witness the
partial—of the central nucleus, when what remains, viz. the
cup in which it was lodged, will very closely resemble some
of the more open forms of starch-vesicles I have noticed in
the paper.

On the Stellate Bodies occurring in the Cells of FREsH-wWATER
“Aues. By the Rev. Wittiam Smirtu, F.L.S.

Tue third volume of the ‘Transactions of the Microscopical
Society,’ containing, at p. 165, ef seq., two papers by G. Shad-
bolt, Esq., ‘ On the Sporangia of some of the Filamentous
Fresh-water Algez,’ has just been placed in my hands.

The subject discussed in these papers having attracted my
attention at various times, and being in possession of ad-
ditional facts, some corroborative of Mr. Shadbolt’s state-
ments, and others which lead me to a conclusion widely
different from that to which he has arrived, I have gladly
embraced the opportunity, which the Society has accorded
me, of bringing the following details under the attention of
its members :— |

The accurate observations of one of the earliest and most
successful students of this department of botany, M. Vaucher,
of Geneva, have established the correct nature of the oval
body, formed by conjugation in the filamentous Algz, which
this author has shown to be a true spore, each such body,
formed by the union of two cells, giving birth, upon germina-

Smitu on Asteridia. | 69

tion, to a single cell, which subsequently, by the ordinary
method of self-division, becomes elongated into a filament
(‘ Histoire des Conferves d’Eau douce,’ Geneva, 1803, p. 66,
et seq., PI. IV. 5, V. 3, VI. 4). [have been able, by personal.
observation, fully to confirm the observations of M. Vaucher in
reference to one species of the Conjugate (‘ Ann. Nat. History,’
2d5., vol. viii., p. 480), and have no hesitation in accepting the
facts as of general import in reference to the entire family. |
have alluded to the circumstance, not only as having a direct
bearing upon the subject of this paper, but also that I may
explain my reason for not employing the term “ Sporangium ”
in reference to the bodies in question, it being evident that
this designation is not applicable to a body which is in itself
a single germ.

With regard to the stellate bodies to which your attention
is now more particularly requested, their true character being
for the present doubtful, it will be better to employ a desig-
nation which does not involve any reference to their nature, and
has regard merely to their form, I shall therefore speak of
them as Asteridia, their general appearance being that of
circular, star-like bodies.

The presence of asteridia is by no means confined to the
family of the Conjugate. I have frequently noticed them in
the Desmidiee, and occasionally in the Diatomacee, though in
these tribes the presence of spinous processes is by no means
a constant character. I have always found (and Mr. Shad-
bolt’s experience seems to be confirmatory, /. ¢., p. 166) that,
if present in a gathering when first made, the numbers of
asteridia rapidly increased when the Alge were retained in
vessels for future examination, and as more or less of change
and decay almost invariably attends the attempt to preserve such
organisms in a limited space, and removed from their natural
habitats, I have hitherto regarded the presence of asteridia as
indicative of disease, as being, in fact, a parasitic, perhaps a
fungoid growth, consequent upon the degeneration of the cell-
contents. x

I am not prepared to put forward this as the true character
of asteridia, but I am prepared to dispute a view of their
nature which confounds them with the reproductive germs,
and shall proceed briefly to state the reasons why such a
character and function are altogether inadmissible.

It is well known that conjugation in the Alge implies the
union of the entire contents of two cells, which contents inter-
mix and become condensed into the reproductive spore, and
that this union is effected by the amalgamation of the contents
of two contiguous cells in the same filament, or by the same

70 Smitu on Asteridia.

process occurring in two cells belonging to different fila-
ments. The mode in which this amalgamation takes place
is either by the breaking down of the walls at the contiguous
extremities of the cells, as in the Vesiculifere, or by the
production of connecting tubes, which form channels of com-
munication between the conjugating cells, whether in the same
or different filaments. ‘These connecting tubes are shown in
the drawings which accompany this paper, Pl. [X., fig. 2 3,
fig. 46, &c.: and it is worthy of notice that, although one
mode of effecting the union of the cells seems to be pretty
general in the same Alga, it is by no means constant, as tubes
connecting contiguous cells of the same filament, or uniting
apposed cells of different filaments, will be found in con-
nexion with the same species: an example is given in fig. 6.*

Now it will be seen by a reference to the figures I have
given, and more particularly to figs. 4, 5, 6, which are drawn
with the camera lucida from mounted specimens of Zygnema
quadratum kindly supplied by Mr. Shadbolt himself, that the
circumstances, as stated above, which accompany the process
of conjugation, altogether negative the opinion that the
asteridia are products of such a process, as the cells contain-
ing these bodies always contain with them a portion of the
original endochrome or cell-contents, which must have been
entirely absorbed had conjugation been effected. Nor are
there, in any case, to be found the connecting tubes which
are necessary to the process in the species we have selected.
It is, therefore, evident that the asteridia are not modified or
matured spores, as the cells containing them have not under-
gone the process necessary to the formation of the repro-
ductive body.

An inspection of fig. 1 will also show the incorrectness of
the conclusion to which Mr. Shadbolt has arrived, viz., that
the asteridia are spores in a more advanced stage. We have
here a portion of a filament of Zygnema quininum, in the cells
of which the gradual formation of the asteridia may be dis-
tinctly traced. Cell @ presents the ordinary and healthy ap-
pearance of the plant ; in cell 6 degeneration has commenced,
and a faint appearance of several aggregations of the cell-
contents may be detected ; these aggregations in cell ¢ assume
the character of perfect asteridia, which in cell d are no
longer in contact with the endochrome, among which they
have been generated. But in no case do we perceive any

* This fact throws some doubt upon the propriety of placing (as Kutzing
has done in his genus Rhynchonema, and Hassall in a sub-genus) species,
which conjugate by tubes connecting contiguous cells, apart from those
in which the conjugation takes place between cells in different filaments.

Smitu on Asteridia. ) (al

semblance of the process of conjugation, or of that mingling
of the contents of different cells so essential to this function
of vegetable life ; and instead of only one body, which is the
invariable result of the conjugating process between two cells,
we have each cell containing several asteridia, the number of
which I have noticed to vary from two to six in a single cell.

Figs. 2 and 3, which are drawn from specimens supplied
by R. Hodgson, Esq., exhibit phenomena which are equally
irreconcilable with the hypothesis I controvert. ‘These sketches
represent portions of filaments of Mesocarpus scalaris. In this
species the reproductive spore is lodged in the inflated tubes
which connect the conjugating cells, while the asteridia,
which were exceedingly numerous in the specimens I examined,
were invariably contained in cells from which no connecting
tubes had been projected. To the above considerations let
me add the fact already referred to, viz. that germination has
in several species of the Conjugate been observed to take
place in the oval or elliptical spore which results from the
process of conjugation, without any previous change in the
form of this body.

The figures, given in the plate which accompany Mr. Shad-
bolt’s paper, bear out to their fullest extent the facts I have
now stated, and might, indeed, have sufficed as illustrations
of my views had I not been desirous of giving as many
examples as possible of a singular, and far from common,
monstrosity, in a curious and interesting class of plants; but
I cannot forbear calling attention more particularly to Mr.
Shadbolt’s fig. 4.

This drawing, which represents Lyngbya floccosa with aste-
ridia, is surely sufficient to prove that such bodies have no
essential connexion with the reproductive spore, for in this
case there are no traces whatever of the conjugating process,
and each cell, whether with or without asteridia, has its full
proportion of endochrome, though in a disturbed and degenerate
condition, the breaking down of the cell-walls in the neigh-
bourhood of the asteridia being a further evidence of the
diseased condition of the filament. On the whole, while I
feel unable to assign a positive character to these singular
parasites, I feel no difficulty in withholding from them the
important office ascribed to them by the gentleman upon
whose communication I have commented. ‘The writer of
that paper will allow me to thank him for the interest he has
excited in a subject which has long caused me no little per-
plexity, and for the very lucid manner in which he has stated
his opinions.

Lewes, Jan. 12, 1853.

72 QueEKETT on Fungus.

Note.—Since the above was read before the Society, I have
met with a brief notice of the Stellate Bodies, to which this
paper refers, in a communication from Mr. G. H. K. Thwaites
to the ‘Annals of Natural History,’ vol. xvii. p. 262, and
dated March 19, 1846. It is satisfactory to find that the
observations and conclusions of this eminent algologist coin-
cide, as far as they extend, with mine. Mr. Thwaites asks
whether the stellate bodies in the cells of Mesocarpus scalaris
may not be an abnormal growth of the nucleus, or perhaps an
internal parasite; describes them as formed from a small
spherical cell, containing an oily-looking fluid; and states, as
I have done, that they are not developed, in the manner of
spores, at the expense of the endochrome of the cells which
contain them.—W. S.

On the Presence of a Funeus and of Masses of CRrysTAatLine
Marter in the Interior of a living Osx Trex. By Joun
QuEKETT, Resident Conservator of the Museum and Pro-
fessor of Histology to the Royal College of Surgeons of
England. (Read January 26, 1853.)

In the month of August of the past year I formed one of a
pic-nic party to visit the well known King Oak, in Marl-
borough forest. ‘The day was stormy at intervals, but there
was little or no wind. Whilst we were all assembled
under a large ornamental shed, erected for the convenience
of visitors to this much-frequented spot, a sudden loud snap-
ping noise was heard, which was followed by a still louder
crash of broken timber. This we found was not occasioned
(as we first imagined) by the fall of a lofty oak, but, as it
subsequently turned out, of only a large limb. Our fears at
the moment were prdatly excited lest this fall might have
been occasioned by one of the junior members of our party
swinging on the limb, but it appeared that he had climbed
into the interior of the King Oak, and, looking out of a hole,
was the nearest spectator of the aecident; his attention
having been directed to it by the noise of the snapping of
wood, and the crash produced by the fracture of the branches
of numerous trees in the neighbourhood, upon which the limb
in question fell.

As soon as our fears were allayed by knowing that our
young friend was safe, some of the more venturesome of the
party, myself amongst the rest, sallied forth to see what had
happened. We found that the King Oak was uninjured, but
that a tree about fifty yards from it, and of very large size,

QuEKETY on Fungus. : 73

had lost one of its finest limbs, and some idea may be formed
of the size of it when I tell you that, at the fractured part, it
was nearly three feet in diameter, and its length, to the first
bifurcation, just twenty-seven paces. On examining the frac-
tured surface, I was surprised to perceive that in the very
centre there was a white flocculent mass, about a foot in
diameter, which at once reminded me forcibly of the appear-
ance presented by a thin layer of cotton wool cemented to
the surface of wood by gum or glue. I looked at it very
carefully, and considered that it must be a filamentous
fungus; and, on examining it with my pocket-glass, I dis-
tinctly saw some sparkling crystals amongst the filaments ;
some of these were very minute, others sufficiently large
to be visible to the naked eye. The wood, at a cursory
glance, appeared perfectly sound, was very moist from the
quantity of sap present, and had a powerful acid smell, like
that of vinegar, which was very perceptible on approaching
the fractured portion. Having satisfied myself of the pre-
sence of a fungus, I turned my attention to the examination
of the fractured surfaces, both of the tree itself and of the
limb, and I could discover no hole or trace of a hole, or
any dead wood leading from the circumference to the centre,
either of the tree or of the limb, but still there was a
peculiar appearance in those parts of the wood itself near the
white filamentous mass above-mentioned, which was due to
the separation of those woody fibres, that were involved in
the fracture. This appearance is still present in a speci-
men of wood I brought away at the time, but which has now
become hard and dry. All its surfaces exhibit a very remark-
able kind of roughness different from that of any oak wood
that has been split by artificial means, and I have tried in
vain to get a surface at all like it by splitting. Having
removed as much of the wood covered with the white mass as
I well could with the aid of a pocket-knife, I took it home
for microscopical examination, and the structure most com-
monly exhibited is that shown in fig. 7, pl. IX. The woody
fibres were much separated in parts, and the spaces between
them occupied by a filamentous fungus and rather large pris-
matic crystals. ;

An idea may be formed of the size of some of the crystals
by the power under which the drawing, fig. 8, was made—
viz. 00 diameters. On removing a portion of the filamentous
mass for examination with higher powers, I found the fila-
ments intimately mixed up with the crystals ; the former were
on an average 1-500th of an inch in diameter, whilst some of
the latter were 1-8th of an inch square ; most of the filaments

Wy)

74 QuEKETT on Fungus.

had numerous globular bodies, about 1-800th of an inch,
adherent to them, but many were scattered about irregularly ;
these I concluded might be the spores—they are shown in
fig. 8. It now becomes a question whether this fungus is of
the same nature as that termed Merulius lachrymans, which is
said to be the cause of dry-rot. I have tried in vain to get
any fungus resembling it in specimens of dry-rot taken from
wood employed in building, and I never recollect seeing any-
thing at all like it in the interior of any specimen of wood,
either living or dead. ‘The crystals are very peculiar, they
may be readily seen by the naked eye studding the surface of
some of the sections; some of them are so intimately mixed
up with the filaments of the fungus that the crystalline matter
appears to have been deposited upon them. A large crystal
is shown in fig. 9, having fungi in its interior ; one of these is
represented in fig. 10.

It would appear, therefore, that the fungi were in a great
measure auxiliary to the fall of the limb in question, if not the
entire cause of it, the effect of the growth of the filaments
being the separation of the woody fibres and a destruction of
the channels through which the sap flowed; this last, being
diverted from its usual course, no doubt lost a great portion of
its watery part by absorption, and the solid matter held in
solution then began to crystallize. The parts most thickly
coated with the fungi are free from crystals; in fact, the fungi
are so numerous as to form a perfect coating over the wood,
some of the filaments being still white, but the majority of a
light-brown colour. In those pieces of wood in which a cavity
or cavities have been formed by the separation of the woody
fibres, the crystals are most numerous. ‘They are generally of
a tabular form, and so transparent that the filaments of the
fungi over which they have formed may be readily seen within
them. I have not yet been able to ascertain the exact chemical
composition of the crystals, but they are soluble in dilute
acids, and probably consist of some vegetable acid, with lime
asa base. ‘The occurrence of fungi, visible to the naked eye,
within a living oak tree, is a fact which few, if any, persons
have yet described ; but the fungus of the dry-rot in wood
which has been exposed to circumstances favourable to its de-.
velopment is far from being uncommon. The fungus now in
question would appear to differ from the Merulius lachrymans
in growing in the interior of a living tree, whilst that is stated
in books to commence growth in the sap-wood on the exterior.
It would be interesting to ascertain whether a similar fungus
exists in other parts of the same tree; and I shall endeavour
to enlist the owner of it in the cause of science, in order that,

QuEKETr on Fungus. : 75

when the time comes for this ancient inhabitant of the forest
to be cut down, some competent person may be allowed to
examine it. It may happen that fungi are more frequently
present in wood than has been imagined, and when such tim-
ber is made a part of a ship or building it may be the first to
show symptoms of decay.

The ravages of fungi are very remarkable. At one of the
early meetings of this Society we had two papers on the decay
of fruit, in which Dr. Hassall showed that the rottenness in
bruised or over-ripe apples, pears, &c. depended upon the
growth of fungi. We have now another instance of it in the
oak, and I think that the further investigation of this subject
would be well worthy the attention of microscopists. It was
a fortunate thing, perhaps, that a microscopical observer hap-
pened to be present when the limb of the tree in question fell,
for, as it was beginning to rain heavily at the time, all trace
of the filaments would either soon have been washed away,
or they would have become so much injured as not to have
attracted notice, and thus the observations contained in this
paper (valueless as they may at first sight appear) would not
have been recorded.

ot saad

REPORT

OF
THE THIRTEENTH ANNUAL MEETING

OF THE

MICROSCOPICAL SOCIETY.

The Microscopical Society of London held their Thirteenth
Annual Meeting, February 11th, 1853,—GeroreEr Jackson,
Esq., President, in the Chair,—when the following Reports
were read :—

1. Report of Council—According to annual custom the
Council have to make the following Report on the state and
progress of the Society during the past year.

The number of members reported at the last anniversary
was 183, including six associates and honorary members.
Since that time there have been elected thirty: making the
number 213. This number must, however, be reduced, by
three deceased and nine withdrawn, giving a total of 201 as
the present number of members, and showing an increase of
nineteen upon the number reported at the last anniversary.

The Council have also to report that a proposal having
been made by the Editors of a new Microscopical Journal
to publish the Transactions of the Society in that work,
the Council have acceded to that proposal; and the first
two parts of the ‘ Quarterly Microscopical Journal’ have been
published, containing the Transactions. ‘These, if required,
may be obtained separately by members of the Society with-
out charge; and the whole publication may be had by the
payment of 4s. per annum extra.

Several new works have been added to the Library, as well
as many new objects to the Cabinet; and there are also in
the possession of the Society various drawings and diagrams,
relating principally to the papers read before the Society, to-
gether with copies of the several parts of the Transactions.

2. Report of Auditors——The receipts and payments have
been as follows :—

Thirteenth Report of

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the Microscopical Society. : 79

The President delivered the following Address :—

GENTLEMEN,—It has been customary on the recurrence of
the anniversary of this Society for the President to make some
observations, in addition to the reports of the Auditors and
Council, on the progress made during the past year.

In compliance with that custom I have first to congratulate
you on the accession to our ranks of no less than thirty new
members ; a greater number, I believe, than have been elected
in any one year since the formation of the Society. That our
members, both new and old, take an interest in our proceed-
ings, is evinced by the increased attendance at our ordinary
meetings; while the subjects brought forward, and the discus-
sions which have taken place on them, sufficiently prove that
a large proportion of us are working microscopists.

By the Auditors’ Report at the last anniversary we were
informed that the funds in the Treasurer’s hands, which at the
previous audit amounted to 85/., had become reduced to the
small sum of one pound and eight pence. At the same time
the publication of our Transactions was considerably in arrear ;
and to add to our difficulties, the Horticultural Society, whose
rooms we have hitherto occupied at a rent proposed by them-
selves, gave us to understand that this rent would be increased
by ten pounds a year. The ground assigned for the increase
was the large amount of accommodation afforded to us; and
inasmuch as the occupation of the council-room every Wednes-
day by our curator was not contemplated when the rent was
originally fixed, there was some show of justice in the de-
mand. It was found also that very few of our members
availed themselves of the opportunity afforded them of coming
here in the daytime to use the microscopes. The Council,
therefore, judged it proper, in accordance with the economy
which the state of our funds so peremptorily obliged us to
exercise, to discontinue the Wednesday attendance of the
curator, by which they hoped not merely to save his salary,
but also to remove the ground assigned for the proposed in-
crease of our rent.

In this latter expectation they have been disappointed. The
Horticultural Society persist in their determination ; and it
has therefore been resolved to remove our meetings to No. 5,
Cavendish Square, where the Chemical Society will afford us
the use of very eligible rooms, together with light and fire, for
the rent which we have hitherto paid without these accommo-
dations.

By the Auditor’s Report, just now read, you will perceive

80 Thirteenth Report of

that, although we have brought up our arrears of publication
to the month of June last, and have paid all our debts, we have
now a balance in hand of 32/., which the economical measures
adopted by the Council will, I hope, increase during the next year.

In order that the members may not be deprived of the
opportunity of using the microscopes, examining the objects in
our cabinet, and consulting and exchanging books, the Council
has engaged a curator to attend at six o’clock on the evenings
of our ordinary meetings, which, it is hoped, will be found
more convenient than the day attendance that has been dis-
continued. :

The necessity for the prompt publication of our Transac-
tions has been adverted to by more than one of my prede-
cessors, and must be sufficiently obvious to all of us; for
when a man has observed a new fact, or suggested an im-
provement in the mode of observing, and has determined to
bring the matter before the public, he is seldom contented
with the notice which the mere reading of his paper may
attract, but is anxious to see it disseminated in print, so that
his claim, either of discovery or invention, may rest on a firm
basis. Unless, therefore, we can offer these advantages, we
must expect that many interesting papers which might other-
wise have come to us will be taken elsewhere, and be sub-
mitted to the public through some more expeditious channel.

In accordance with these views, the Council has made an
arrangement with two of our members, who have commenced
a Quarterly Journal of Microscopical Science, for the regular
printing of our Transactions in that periodical ; so that authors
will not only see their papers promptly published, but will
also enjoy the benefit of the large circulation which the Journal
has obtained. Our members, also, in addition to a copy of the
Transactions, will obtain all the other matter which the
Journal contains for one shilling per number.

On the value of this matter, as two numbers have been
already published, it is needless for me to expatiate at any
length. Besides interesting original communications from
observers in our own country, by means of translations and
extracts from foreign journals and reviews of foreign works
it affords to the mere English reader the knowledge of what is ~
being done by microscopists in all parts of the world; and by
thus giving a starting point to his inquiries, prevents his
wasting his time and energy in re-discovering what has been
already observed. |

The publication in full of our Transactions up to the end
of June last, and the abstracts in the Journal of the papers
read before us in October, November, and December, render

the Microscopical Socrety. he 81

it unnecessary for me to go so deeply into the contents of these
communications as has been usual at former anniversaries.

Mr. Shadbolt’s paper, containing a variety of useful prac-
tical information on the habitats and mode of collection of a
number of beautiful microscopical objects, was listened to
with much attention, and elicited many remarks and inquiries,
and, had it not been already published in the Journal, would
have demanded from me a more extended notice.

The paper of Mr. Simonds records an interesting patho-
logical fact. As a medical man, I cannot help regretting that
pathology is a subject on which we have very few communica-
tions; for I feel assured that the investigation of the products
of disease is one of the most 7mmediately useful purposes to
which the microscope can be applied ; and I believe that such
communications would be well received, not merely by those
of my own profession, but by the members generally.

The paper of Mr. Mummery on the development of Tubu-
laria indivisa, and those of Mr. Busk and Mr. Williamson on
Volvox globator, contain a vast amount of well-illustrated
microscopical observations.

The same praise is due to Mr. Busk’s paper on Starch,
_ which also teaches us the useful lesson, not to be satisfied with
examining things in their natural state, but, by applying re-
agents under the microscope, to combine chemical research with
microscopical observation.

The subject of Microscopical Photography, on which Mr.
Delves has favoured us with a communication, accompanied
by some beautiful specimens, is one of great interest. That it
will attain a high degree of perfection no one who knows the
persons engaged in its cultivation can reasonably doubt. There
is, however, a difficulty in its application, which, I fear, will
materially limit its use.

Those who have been in the habit of using the microscope
since the first introduction of achromatic lenses must have
noticed that in proportion as the object-glasses have increased
in aperture and improved in definition they have lost the
power of penetrating to any depth; and this has now been
carried to such an extent that when we examine with a high
power any but the thinnest objects lying in an almost mathe-
matical plane, we can only do so effectually with the finger on
the fine adjustment to regulate the focus for the particular
point on which the eye is fixed.

This precision of focus, which is a necessary consequence of
precision of definition, must have the effect of confining pho-
tography (except with low powers) to the representation of the
class of objects above described; or of only allowing us the

82 Thirteenth Report of

alternative of having portions of them well delineated while
the rest is indistinct. Other difficulties attending Micro-
scopical Photography have been pointed out in Mr. Hodgson’s
paper, on which it is not necessary for me to dilate.

In spite of these obstacles, I venture to prophesy that this
beautiful art will flourish; for its want of universal appli-
cability need not prevent its use in the numerous cases to
which it is appropriate.

The paper of the Rev. William Smith on the Stellate
Bodies occurring in the cells of fresh-water Algze gives some
further details of these plants, which may hereafter assist us
in forming a more correct theory of their physiology.

Our Secretary, to whom we have formerly been so much
indebted for valuable contributions, has recently read a very
interesting account of some observations he has made on the
presence of a fungus, and of masses of crystalline matter, in
the interior of a living oak tree ; a circumstance which does
not appear to have been previously noticed, and which hardly
admits of a satisfactory explanation in the present state of our
knowledge. It is not, however, less worthy of record on that
account ; for all sound theory must be based upon carefully-
observed facts; and the first fact of a kind is at least as
valuable as those which may hereafter follow it.

The very large demand for first-class microscopes, which
has increased rather than diminished during the past year, has
stimulated the makers to use every exertion to extend to the
utmost the apertures of their object-glasses. Messrs. Smith
and Beck have produced a 4-10th inch of upwards of 90°,
chiefly valuable for the examination of opaque objects. Mr.
Ross has lately made some objectives of 1-8th inch focal
length, and 155° of aperture, which, by permitting very
oblique illumination, bring out the markings on the most
difficult test objects in a highly satisfactory manner. Mr.
‘Wenham, in following up his experiments to ascertain the
limits of useful aperture, has constructed a glass of 170°, and
1-12th inch focus ; but is still of opinion that nothing is gained
beyond 150°. From a very brief examination of his object-
glasses, I am inclined to differ with him, and to think that for
the purpose of merely discovering the existence of very close
lines or dots the aperture cannot be too great. For the useful
application of the microscope to minute anatomy and physi-
ology a much smaller aperture will suffice, which, from not
requiring such careful adjustment, and such close proximity to
the object, is far more convenient in use.

When we consider that the real aperture of an object-glass
is the chord of the angle at which light is admitted, and that the

the Microscopical Society. | 83

chord of 170° is more than ‘996 of the diameter of a circle,
we may be certain that if the extreme limit has not already
been reached, its further extension will scarcely be appreciable.
To correct the aberration of these glasses as far as possible,
and to bring them to the neatness of definition that has been
attained in those of more moderate aperture, must now be the
aim of our scientific opticians.

A very useful addition to the mechanical arrangements of

the microscope has been contrived by Mr. Brooke. In former
days, when our objectives were single lenses, it was usual to
set four or six of them in a wheel, by turning which the
power could be changed in a moment. Our present object-
glasses, consisting generally of three achromatic combinations,
requiring to be set in tubes of some length and thickness,
cannot be compressed into so small a space. Mr. Brooke has,
however, effected the same purpose to the extent of two powers.
To the nozzle of the microscope an arm is screwed, projecting
in front, and carrying a pin on which a bar revolves, to each
end of which an object-glass is screwed, Either of these, by
rotating the bar, can be brought under the body of the instru-
ment, while the other is carried beyond the stage so as to be
quite out of the way. Object-glasses of one inch and one-
quarter inch mounted in this way are found to be very con-
venient when pursuing microscopical researches; the one to
take a general view, and the other a particular one, of the
object under inspection.
- Mr. Brooke also exhibited a neat little contrivance for con-
verting a pocket eye-glass into a table microscope. ‘Two
straight square pieces of brass are halved into each other, and
the pillar on which the eye-glass slides screws into the inter-
section, the straight pieces forming the foot. The whole
makes a useful stand, and packs into something smaller than
an ordinary spectacle-case.

Mr. Ross has constructed a very comprehensive microscope-
stand, furnished with right-lined and circular motions, not
merely to the stage but to what may be called the sub-stage, or
that part which carries the different illuminators for trans-
parent objects. All these motions being effected either by
pinions or screws, the various adjustments are made with
great comfort to the observer. ‘The instrument is heavy, and
the quantity of excellent work in it necessarily renders it
somewhat costly.

Messrs. Smith and Beck have adopted an improved method
of attaching the object-glass to the body for the purpose of
preventing the excentricity which is frequently caused by the
imperfection of the screw. They have also carried the same

84 Thirteenth Report of

principle into the construction of the eye-piece by attaching
the cells to the tubes by cylindrical fittings.

Here, Gentlemen, I would willingly conclude; but I have
still the melancholy duty remaining of recording the death of
three of our members, a duty from which my predecessor was
last year happily exempted.

Of Mr. Edward Stokes I had no personal knowledge ; but
I have been informed that he was a zealous cultivator of
science. |

Mr. Dalrymple and Dr. Mantell have both left names which
will not speedily be forgotten, and which merit a much more
extended notice than it is in my power to give.

John Dalrymple was the eldest son of William Dalrymple,
a highly distinguished surgeon at Norwich, under whom he
received the early part of his professional education. He
afterwards studied at the University of Edinburgh, and in
1827 became a member of the Royal College of Surgeons in
London, and settled in the city. In 1832 he was elected
Assistant-Surgeon to the Royal Ophthalmic Hospital, and
Surgeon in 1843. In 1847 he retired from that office on
account of ill health, and was appointed Consulting Surgeon.
In 1851 the Fellows of the Royal College of Surgeons elected
him a Councillor, He published a work on the Anatomy of
the Eye in 1834; and a splendid one on the Pathology of
that organ he only just lived to complete. In fact, he revised
the last number but a few days before his death. His style
is clear and concise ; and the soundness and precision of his
views, and the accuracy of his delineations, are universally
acknowledged by the profession. In 1839 he removed from
the city to the west end of London, where his practice in-
creased, and latterly had become greater than was compatible
with the state of his health. In addition to his own peculiar
department of surgery, in which he had attained the highest
eminence and the full confidence of the profession, he suc-
cessfully prosecuted the delicate and interesting science of
microscopical anatomy, both human and comparative. He
was an original member of this Society, and one of our first
council ; and he contributed a valuable paper ‘‘ On the Ar-
rangement of the Capillary Vessels of the Allantoid and Vitel-
line Membranes in the incubated Egg” to the first volume of
our Transactions. Until illness obliged him to spend bis
evenings at home, he was a frequent attendant at our meet-
ings; and his remarks, when he took a part in our discus-
sions, were characterised not less by clearness and precision
than by the modest and gentlemanly tone in which they were
delivered. |

the Microscopical Society. 85

Soon after the death of Dr. Gideon Mantell a brief memoir
of him appeared in the Athenzeum, from which I shall extract
a few particulars. Although a member of the medical pro-
fession, he was not a graduate in medicine, but derived his
title from the degree of LL.D. conferred by a foreign uni-
versity. He commenced his career as a general practitioner
at Lewes; removed to Brighton in 1835, and to London in
1839, residing first at Clapham, and afterwards in Chester-
square. He was naturally an enthusiast, and, gifted with
quick observation, he would have distinguished himself in
almost any branch of science. ‘Ihe accident of his position
made him a geologist; for little was then known of the
Wealden formation, or of the fossils which it contained. Sel-
dom has an observer had a richer field for the exercise of his
powers, and seldom has an opportunity been better seized. In
the course of a few years he collected together a museum of
specimens from the Wealden and the chalk which now forms
a portion of the British Museum, the trustees of that institu-_
tion having purchased it for 5000/. His first paper, published
in 1813, was on the organic remains discovered in the en-
virons of Lewes ; and from that period almost to the time of
his death his literary labours were unceasing ; for on the sub-
jects of Zoology and Botany no less than sixty-seven papers
and works have been enumerated. When it is remembered
that during all this time he was pursuing the active practice
of his profession, contributing papers to the medical journals,
and occasionally writing on other subjects, we may form some
idea of his indefatigable industry.

Dr. Mantell had also the satisfaction of making known the
important discovery, by his son, of the remains of the gigantic
birds of New Zealand, of which he possessed many very fine
specimens, and on which he wrote several papers.

Of his talents as a popular lecturer I can speak from my own
observation. Possessed of a rapid and even flow of appro-
priate language, sometimes rising into eloquence, and being
enthusiastically fond of his subject, he managed to inoculate
his audience with the same enthusiasm, and therefore had no
difficulty in keeping up their attention even when he tres-
passed considerably beyond the accustomed hour. He was an
occasional but not frequent attendant at our meetings.

Permit me, Gentlemen, in conclusion to thank you for the
kind indulgence with which you have received my very im-
perfect endeavours to fulfil the duties of your President. Of
their imperfection no one can be more sensible than myself;
but at the same time no one can more sincerely desire the con-
tinued prosperity of the Society, or strive more to promote it.

86 Thirteenth Report of the Microscopical Society.

Resolved unanimously—That the Reports of the Council
and Auditors be received; and that they and the President's
Address be printed in the Transactions of the Society.

The law relating to the election of officers was then read ;
and the Society proceeded to ballot for the officers and four
new members of council for the year ensuing.

The ballot having been taken, the following were declared
elected :—

Officers.
President: Wes ek. 2s GeEoRGE Jackson, Esq.
Treasurers nic 98 4 N. B. Warp, Esq.
Seorétarysds. 26. 24 JoHN QUEKETT, Esq.

Assistant Secretary. . Mr. Joun WI iis.

New Members of Council.

W. Gitiert, Esq.
Joun Les, Esq., LL.D.
Rogert WaArineTON, Esq.

F. H. Wenuam, Esq.

In the room of
M. S. Leae, Esq.
M. Marsuatt, Esq.
ALFRED Ros.ine, Esq.
J. B. Stmonps, Esq.

Resolved unanimously—That the thanks of the meeting be
given to the President, Treasurer, Secretary, and Members of
Council, for their services on behalf of the Society during the
past year. |

b ABE)

On the Minute Structure of a Species of Fausastna. By Pro-
fessor W. C. Wittiamson. Communicated by Matthew
Marshall, Esq. (Read June 22, 1851.)

In the last memoir on the Foraminifera which I laid before the
London Microscopical Society, I pointed out the existence of
a curious system of tubes and canals, penetrating the parietes
and septa of several species of Foraminiferous shells. In
Polystomella crispa these chiefly presented themselves in the
form of large canals passing through the calcareous umbilical
regions. In some species of Nonionina and Amphistegina
they existed as a dense network of minute canals, having their
external orifices at the peripheral margins of the discoid shells.
In the latter examples the canals were of small diameter, and
their use in the economy of the living animal very dubious.

On making a number of sections of a species of Faujasina
(D’Orb.) from Manilla I discovered the existence of a much
larger and more interesting arrangement of tubes than any
that I had previously seen. ‘This shell is constructed on the
inequilateral plan of the common Truncatulina tuberculata.
Its inferior surface is flat, the corresponding extremities of
the segments being arranged on a nearly uniform plane. As
successive convolutions have been added to the antecedent
ones, they have assumed the arrangement of a series of hollow
cones placed over one another, the additions to the length of
each new segment being confined to its upper extremity.
Hence, whilst inferiorly all the convolutions are visible, on the
upper surface we only see the outermost one presenting the
aspect of a truncated cone.

Fig. 1, Pl. X., is an enlarged representation of the lateral
appearance of the shell, viewed as an opaque object. Whilst
the vertical septal lines (1 d) are translucent, the intervening
parietes of the segments (1 9), in which the minute foramina
exist, is of an opaque gray colour. The inferior peripheral
margin (1 f), and its continuation at the flat inferior surface,
constituting the spiral septum (fig. 2 ¢) separating the con-
volutions, exhibit the same translucent aspect; as does also
the truncated apex of the cone (1 d'), towards which all the
vertical septa converge. In nearly all the Foraminifera a
translucent line appears to mark the existence of a subjacent
septum. The segments, which do not extend to the summit
of the shell, communicate with one another by one very ee
oral aperture (1 e).

Along each of the vertical septal lines (1 d) there exists an
irregular double row of very distinct pits or depressions (fig.
6 f). Similar pits are seen inferiorly in the radiating septa

VOL. I. h

88 WILLIAMSON on Faujasina.

which divide the different segments of each convolution (fig.
2 b andd), but they do not occur in the peripheral margin
(1 f and 6 e), or in the spiral septum (fig. 2 e). At the upper ex-
tremity of the shell similar, but larger, pits are seen both on the
flat truncated surface (1 da’) and on the sides intervening be-
tween it and the upper portions of the segments (6 6). On
making a series of sections of the shell we learn that these pits
are the external orifices of a curious system of intra-septal
canals and spaces, ramifying in its interior.

Fig. 2 represents a thin superficial section of the inferior flat
surface, viewed as a transparent object. _Thus examined, the
conditions are reversed. ‘The foramina in the parietes of the
hollow segments tend to intercept the light and look dark,
whilsti'the solid calcareous septa are translucent and transmit
it freely. ‘This section was made a little below the peripheral
margin and parallel with the points a,a in fig. 1.

The walls of the segments (2 a) exhibit the ordinary forami-
nated aspect, and the segments themselves are arranged in
the usual spiral manner. The spiral contour is lost in the
centre of the section, owing to the circumstance that it there
becomes very thin, and passes under the central cells which
are placed a little above the level of those which surround
them. In the radiating septal lines are seen numerous small
orifices (2 b), which open by means of short canals (fig. 5h, h’)
into the interseptal spaces immediately above them. As
already observed, these orifices do not exist in the spiral sep-
tum (2 e), but here and there even this superficial section ex-
hibits traces of deep-seated canals passing through the septum
and uniting the orifices belonging to contiguous convolutions
(2.c). In this portion of the shell the apertures are usually
in single rows ; but towards the exterior of the outer segments
we sometimes see them arranged in pairs (2d). It is of
course the external surface of the base of the shell that is re-
presented in the drawing.

On making a second section parallel to the last, but a little
above the peripheral margin, in the plane of the points 1 4, d,
we have the appearance presented by fig. 3. The drawing
represents this section as seen when viewed in the opposite
direction to the last, viz. looking at its upper or inner surface,
and towards the base of the shell—some of the foraminated
parietes of which are still preserved.

We now perceive that there exists a number of large branch-
ing intra-septal tubes and passages, which commence at the
innermost segments and proceed in a radiating manner towards
the periphery. As each of these tubes emerges from the
septum separating two contiguous segments, and reaches the
spiral one intervening between two convolutions, it exhibits a

WILuraAMson on Faujasina. 89

marked tendency to divide into two branches (fig. 3a, 6), one
of which is usually ina plane a little above thefother. On
tracing back these tubes as they proceed from the outermost
to the inner convolutions, we perceive that the bifurcations,
which at one time marked the outer extremities of each series,
serve two purposes: they are designed, primarily, to multiply
the number of the external orifices ; but in addition to this, they
subsequently facilitate the establishment of a free communica-
tion hetween the internal intra-septal spaces and those of the
newer convolutions, in which the septa are much more nu-
merous ; but though a lateral divergent communication is thus
maintained, I have only seen one instance in which a direct
lateral communication was established between two transverse
septa of the same convolution, parallel with the spiral septum.
The exception is seen at fig. 3c. In this respect the species
under consideration differs materially from the forms described
in my preceding memoirs. The small circular apertures which
appear along the course of these tubes, mark the points where
the section has traversed the orifices of the canals descending
to the inferior surface of the shell.

Fig. 4 represents a third section made across the points fig.
lec. This section has cut through the shell a little above
the superior extremities of the cells belonging to the central
convolutions ; a few of those belonging to the second spiral being
seen at 4a. The outermost convolution, on the other hand,
has been intersected across its large oral (?) apertures (fig. 1 e),
revealing the nature of the connection (40) that exists be-
tween contiguous segments. We now see that the portions,
which in the section fig. 3 had the appearance of large
radiating tubes, are really the lower borders of vertical
intra-septal spaces (fig. 4 ¢ c’), which also give off true
divergent cylindrical canals from their external margins, pene-
trating the thick parietes of the shell. These spaces extend
from the top to the bottom of each septum, and only assume
the form of canals when they approach the peripheral shell
walls. The connecting branches which unite the spaces of
different convolutions (fig. 3 5) are also tubular.

The septa of the second convolution in this section exhibit
similar intra-septal spaces (4 d), which communicate exter-
nally, as just described, with those of the outermost convo-
lution, and also open internally into a large and very irregular
central cavity (fig. 4 e and 5q). The true nature of this cavity
will be better understood on referring to fig. 5, which repre-
sents a vertical section of this instructive object, passing nearly
through its centre. I am not quite certain whether it has
actually traversed the primordial cell, but if not, it has cer-

h 2

90 WILLIAMSON on Faujasina.

tainly crossed the second one (see fig. 3), which is seen at a,
along with four others, 6, c, d, and é, in the order of their suc-
cessive development. "Whilst their inferior portions of the seg-
ments are nearly on an uniform level, the upper extremites of
those belonging to successive convolutions become rapidly
elongated, leaving between them a large, irregular, conical
space (fig. 5 g, g), the inverted apex of which rests upon the
most central segment (5 a) and communicates with the inferior
surface by means of the canals fig. 5’. Similar canals are
also seen at 5 h, passing upwards into the inter-septal spaces ;
whilst at 572’, corresponding ones proceed inwards through the
respective septa of the cells c and d—in the translucent walls
of the latter of which their direction, and the extent of the
inter-septal space may be traced.

I have not in any one instance found these spaces, or their
divergent canals, communicating with the interiors of the seg-
ments, though at the first glance many of them appear to do
so, as is the case with the inner margin of the large segment
fig. 5d. But from the examination of a considerable number
of sections, [am satisfied that where such an appearance exists,
it is either the result of an accidental fracture or an optical
illusion; and that the only direct communications existing
between the two parts of the organism, are through the pseu-
dopodian foramina, many of which open into the tubular por-
tions of these passages (figs. 3d and 4f); but never, as far as
I have observed, into the intra-septal spaces.

But the section now under consideration, in common with
several of the others just described, presents a new and curious
feature. The cavities in the translucent calcareous shell are
thickly lined with a dark olive-brown substance, apparently
the residuum of the soft animal. ‘This substance not only
exists in the interior of all the segments, closing up the oral aper-
tures, as at 5 f, but also occupies the intra-septal spaces and
their respective canals, as well as the irregular cavity in the
umbilical centre of the shell. If this substance is really the
desiccated soft animal—and of this we should not have enter-
tained a doubt, had it existed only in the interior of the seg-
ments—it is evident that in this species the gelatinous tissue
has not only filled the true chambers but has also occupied
the intra-septal canals and passages. The specimen from
which the section, fig. 4, was prepared, exhibited the same
appearance, and traces of it oecut in all; hence it appears most
probable that this brown substance is really the desiccated soft
animal. If this should prove to be a correct conclusion, it is
curious that the only medium of communication bétween the
soft tissues inhabiting the spiral segments of the shell and those

~ Witaramson on Faujasina. | 91

occupying the intra-septal and central passages, should have been
the minute pseudopodian foramina. ‘The structure is so very
different in this respect, from anything that has been previously
observed, that I am afraid to speak with too much certainty on
the subject, though I entertain but little doubt respecting it.

On examining the external contours of young examples of
this species, we ‘often find the apex occupied by a deep and
irregular depression, surrounded by the projecting upper
extremities of the segments constituting the external convolu-
tion. This depression, which is really identical with the
irregular central cavity (fig. 59,9), subsequently becomes
arched over by a calcareous layer (fig. 1d), derived from the
upper portions of the newer convolutions. The roof thus
formed is perforated by large apertures (fig. 65), through
which a free communication is maintained between the
external medium and the enclosed space. The nature of the
latter varies considerably. Sometimes it exists in the form of
a large irregular cavity, as already described, and at others as
an intricate network of large canals. ‘The character of the
external orifices also varies. In some examples they are large
and patent, as in fig. 66; in others, numerous smaller tubes,
ascending from the subjacent network, converge at some super-
ficial depressions which occupy the position of the larger
orifices. Fig. 6 represents a thin superficial section made in
the plane of the oblique sides of the conical shell and exhibits
three septa (6c), with the large orifices of their intra-septal
canals (6 f), part of the external parietes of four segments
(6d), densely perforated with minute pseudopodian foramina,
part of the inferior peripheral margin (6 e), and a small lateral
portion of the dome-like apex of the shell (6a).

The preceding facts are sufficient to show that the subject
of this brief memoir presents a very different structure from
any of the Foraminifera hitherto described. Whether or not
my supposition as to the probable occupation of the intra-
septal canals and spaces by the gelatinous soft animal be
established, it is obvious that this organism supports the con-
clusion at which I arrived in a preceding memo1, viz. that the
soft animal had the power of extending itself externally far
beyond the limits of any individual segment, and would thus
be able to secrete calcareous matter in other situations than the
mere parietes of its own segment. It is only in this way that
we can explain the production of the dome-like covering which
encloses the central umbilical cavities and their ramifying
canals. But if it should be ultimately proved that the soft
tissues have occupied all these irregular cavities, we shall then
have a form of organization which, from its great variability

92 Wixiramson on Faujasina.

of contour, will approach much more closely to the calcareous
sponges than any hitherto described.

I am well aware that, to many, these dry details will appear
unnecessarily and tediously minute; but it must be remem-
bered that, until we are accurately familiar with all the lead-
ing types of structure existing in this interesting group of
organisms, we cannot be in a condition to arrive at final con-
clusions respecting their nature and zoological position.

Manchester, May 21st, 1851.

Notice of a Diatomaceous Earth found in the Isle of Mull. By
Witttam Grecory, M.D., F.R.S.E., Professor of Chemistry
in the University of Edinburgh. Communicated by Pro-
fessor Joun E. Quexetr. (Read March 23rd, 1853.) ,

Tuts earth was discovered, about two years ago, by the Duke
of Argyll, who gave a short account of its geological position
to the Royal Society of Edinburgh. It constitutes a bed,
resembling marl in appearance, lying in a rough piece of
ground, at Knock, near Aros, between Loch Baa, a fresh-water
lake, 3 miles long and 1 mile broad, and the sea. The lake
is about 30 feet, the land about 40 feet, above the sea-level,
and the lake is surrounded with high mountains on all sides
except the west, where its waters flow towards the sea, passing
through the rough district, boggy in parts, above mentioned,
which is about a mile broad. The marl-bed, as it is called
on the spot, lies within 50 yards of the lateral granite rock,
and half-way from the lake to the sea. The surface of the
land between the lake and the sea is very uneven, covered
with large stones, gravel, and sand. At one part there is a
hollow, which in winter used to become a small loch, in
summer only a stagnant pool, and in draining this the bed of
marl was discovered. It was filled in summer by a small
stream unconnected with the lake. The bed rests on the
gravel, which again rests on the granite of which the whole
district is formed. As there is no formation of an epoch be-
tween those of the granite and of the gravel, we cannot, from |
its position, ascertain precisely the geological period at which
the bed was deposited. The Duke of Argyll regards the
gravel as belonging to the Diluvium, and the Infusorial de-
posit as comparatively of very recent origin. But there is
reason to think, from the character of the species, that the
deposit may belong to a more remote epoch. Ehrenberg, to
whom I sent a portion of it, writes to me, that he thinks it
probably connected with the Tertiary, or at all events, with

“

GREGORY on Diatomaceous Earth. | 93

the Quaternary period, but he had only been able to make a
partial examination of it at the time he wrote.

This deposit must not be confounded with the Leaf-bed,
also discovered in Mull by the Duke of Argyll; for that bed,
which also contains a large number of Diatomaceous remains,
occurs at a place 20 miles from the deposit now under con-
sideration, and is found between two beds of volcanic trap,
showing that the Dicotyledonous trees—remains of which
abound in it—must have lived before the eruption which gave
rise to the upper trap-bed, whatever may have been the period
of that eruption.

To return to the Infusorial deposit. The Duke of Argyll
thinks it possible that the waters of Lock Baa, which now
pass to the sea at a distance from the deposit, may, at one
period, have flowed through the hollow where the deposit is
found. Mr. Campbell Paterson, a gentleman residing on the
spot, thinks that the sea at one time communicated with Loch
Baa, and that the present barrier is the result of some geolo-
gical change or convulsion. The gravel and sand, he says,
exactly resemble those now forming in the neighbouring sea ;
and although he has not observed any marine shells in the
gravel, he thinks that the rocks at a higher level bear marks
of the action of the sea. ‘These are points on which I cannot
speak without a personal knowledge of the locality, but the
deposit appears to contain only fresh-water organisms.

The Duke of Argyll kindly gave me a small portion of the
earth first discovered, which happened to be very pure, and
which he stated to contain Naviculacee. On examining it, |
was struck with tle variety of forms, and resolved to study it
more closely ; this I have only been able recently to do, and
I think the results may prove not uninteresting to the Micro-
scopical Society.

The Mull earth is, in the purest specimens, when dry,
almost white, and much resembles chalk, being light, friable,
and adhering to the fingers. But more commonly it has a
pale fawn colour, and it is frequently strongly tinged with iron.
The lightest and whitest specimens contain hardly anything
besides siliceous organic remains, for the most part entire, but
with some fragments. Other portions, which are denser,
contain also many fragments of quartz of various sizes, and
vast numbers of comminuted fragments of lorice. In the
densest and worst, the quartz or sand and the fragments en-
tirely predominate, and these can hardly be cleaned. ‘The
specimens of middling quality, as well as the inferior ones
which I at present possess, contain a great many minute
fragments of lorica, often exceeding half or three-fourths of

94 GREGORY on Diatomaceous Earth.

the mass. These ‘fragments form an excellent polishing
powder, which may be had of various degrees of fineness. I
find it best, except in the case of the very purest specimens,
first to ignite the earth over the spirit-lamp in a platinum
capsule, till the black colour first caused by the action of
the heat on the organic matter present is burned off, and the
earth is again nearly white. I then digest it for some hours
in strong nitromuriatic acid, which removes the iron, and,
after washing away the acid, press the lumps in water gently
with the finger till the whole is diffused in the water. It is
then elutriated as usual, to separate on the one hand the
coarse sand, if any be present, and, on the other, the com-
minuted fragments. The slides now offered to the Society
were prepared in this way from earth of but middling quality,
my supply of the purest having been very small and long ago
exhausted ; while the deposit being at present, and for months
past, flooded, it is impossible to procure a fresh supply of
the purest earth.

In endeavouring to identify the species present in ists
earth, I found the greatest difficulty from the want of any
work containing figures of all the known species. The only
figures I could procure were those of Ehrenberg’s Atlas,
1838, and those of the last edition of ‘ Pritchard’s Infusoria.’
The former, of course, does not contain the very numerous
species added to the list since 1838, and the latter has sel-
dom more than one or two species in each genus. I had also
Kiitzing’s ‘Species Algarum,’ without any figures. But I was
able, after studying a good many slides of excellent quality,
to distinguish somewhere about 65 forms, although I could
not with any confidence name above one half of the number,
Under these circumstances, I ventured to apply to the Rev.
W. Smith, to whom I was fortunately able to send an excel-
lent specimen of the earth. That distinguished naturalist
had the very great kindness, in spite of his absorbing occupa-
tions, to examine the earth, and to send me the following list
of species which he has detected in the specimens sent. The
names are those adopted in his forthcoming synopsis :-—

Pinnularia major Pinnularia gracilis
‘5 acuminata + lata
its oblonga ap alpina
p viridis Navicula serians
fr divergens nm rhomboides
oe acuta £ ovalis
¥ radiosa ig dicephala
S| mesolepta eA firma —
st interrupta geese angustata
* Tabellaria Gomphonema acuminatum
a gibba 3 cruciatum

GREGORY on Diatomaceous Earth. | Q5

Gomphonema Vibrio Himantidium gracile, Kutz.

- capitulatum a bidens, W. Sm.
Amphora ovalis * pectinale, Kutz.
Stauroneis Phoenicenteron > arcus, Kutz.

e gracilis af major, W.Sm.
if linearis undulatum, Ralfs.
anceps Tabellaria frustrata, Kiitz.
Gymatopleura elliptica 2 ventricosa, Kutz.
3 apiculata Epithemia turgida
Cocconeis Thwaitesii * gibba
Bs Placentula ~ EKunotia gracilis
Surirella Brightwellii » retrorsum
‘~ biseriata ; ,Wiadema
Cymbella Helvetica Synedra capitata
ee maculata os A Ice pS
e sativa Fragillaria capucina, Kutz.
ms affinis Orthoseira viridis, W. Sm.
™ cuspidata ing ouchalcea, W. Sm.

It will be perceived that Mr, Smith has found, in the speci-
mens sent to him, 59 species of fresh-water Diatomacee.
As I] had made sketches of all those forms which I could not
name, I was easily able to identify Mr. Smith’s species. I
have stated that I had distinguished about 65 forms. I
believe that some of these were side-views of species un-
known to me at the time, and others, in all probability,
accidental varieties. But I also think it probable that there
may be a few species in the deposit which do not occur in
the portion seen by Mr. Smith. At least, I am quite certain
that that portion differs remarkably in some points from that
which I had under examination at the same time. For ex-
ample, in Mr. Smith’s specimen, of which he kindly sent me
two slides as I had not tested it myself, I find that there are
numerous and fine lorice of Epithemia turgida—a species
which I had indeed observed in mine, but which I had found
remarkably scarce. I have reason to think that hardly any
two specimens will be found exactly to agree, and it is quite
natural that different parts of the deposit should differ in the
prevailing forms. Among the forms which I thought I had
observed, but which Mr. Soa iedad) caoiindest with, are Melo-
siera distans, and possibly MM. nummuloides ; Eunotia
Triodon, and EL. Pentodon; possibly E. fabra, and one or two
more. But most of these, if they do occur, are very scarce ;
and therefore I do not venture to add any names to Mr.
Smith’s list until I shall be confirmed by him or by some
other experienced authority. There are several other forms,
also doubtful, which I thought I had seen, but I need not
name them.

The Mull earth is characterised by several peculiarities.
_ First, by the abundance of very fine specimens of the Navi-

96 GREGORY on Diatomaceous Earth.

culacez, especially of the genera Pinnularia (14 species),
Navicula (6 species), and Stauroneis (4-species). There are
many splendid individuals of Pinnularia major (some 1-50th
of an inch in length), oblonga, virides, divergens, and others ;
and a few, but these very fine ones, of. P. data, and of the rare
and beautiful P. alpina. Navicula rhomboides and N.
serians are particularly frequent and fine, as is also Stauronets
Phenicenteron. 2ndly. It is characterized by the abundance
of Cymbelle of which there are 5 species. drdly. There is
a remarkable development of the Eunotie, as LHunotia
Tetraodon, E. Diadema, Himantidium Arcus, H. bidens, and
the 4 other Himantidia and Epithemia turgida. Athly. There
is a great abundance of Tabellaria fenestrata in every stage
of development, some specimens being 10 or 12 times as long
as others, but not broader, and of T. ventricosa which, how-
ever, occurs almost always short. OSthly. There is a remark-
able abundance of fine specimens of Gomphonema coronatum,
and fine individuals of G. acuminatum also occur. ‘The
genera Amphora, Cymatopleura, Cocconeis, Surirella, and
Nitzschia occur less abundantly, and in some cases are
very scarce. Fragilaria capucina, Kiitz., Orthoseira viridis,
W.Sm., and O. ouchalcea, W.Sm., are abundant, as is Synedra
biceps. I have observed the variety 6 recta, Kiitz., of this
species.

Besides the 59 species named by Mr. Smith (and I would
again remind the Society that the names in the above list are
those of Mr. Smith’s daily expected Synopsis), there is one
form, to which I directed his attention, and which he cannot
with certainty refer to any known genus. This form is
abundant in all specimens of the earth, and is therefore an
additional characteristic of it. It varies from 1-600th to
1-470th of an inch in length, and has usually the form of a
plano convex lens, with two notches near the ends of the
plane or very slightly concave side. It is broadest in the
middle, and has sharp apices (fig. 1). At other times
the apices are less sharp and the ends broader (fig. 2). It
is finely cross striated, and Mr. Smith has ascertained the
number of strie to be 44 in 1-1000th. It requires a very
good glass to make out the striz, and it 1s possible that this
form, from its abundance in the Mull earth, may be found
available as a test object. For a long time I could not make
out the striz (although I felt sure of their existence from the
resemblance or aspect to other forms known to be striated)
with a glass which had sufficed for all the other forms. But
with a first-rate object glass, and good management, the striz
may be shown and counted. It is possible that this form

GreEGoRY on Diatomaceous Earth. | 97

may be an immature one, but to what are we to refer it? It
differs from Himantidium Arcus and Eunotia gracilis in the
number of striz, and Mr. Smith thinks it must stand near
Eunotia Arcus, Kitz. Navicula Arcus, Ehr. It is not, how-
ever, that species, nor is Mr. Smith sure that it is of that
genus. He is to examine it more fully, and the matter is
therefore in good hands. I may add, that while it has a
general resemblance to small specimens of Himantidium
Arcus, or of other allied species, it does not commonly occur
where these are abundant. I have looked at a number of
Diatomaceous earths, in many of which there were all the
common species of Hunotia and Himantidium, but have only
seen this form in one, namely, in a slide prepared by Mr.
Topping, and labelled ‘‘ from the banks of the Spey.” This
slide has many things in common with the Mull earth. Any
of the slides sent with this paper will exhibit numerous
examples of this form.

I have further to add, that an average specimen of the Mull
earth, on being analysed, was found, after being dried at
212°, to be composed of —

Silica ~ - - - - - 70°75

Protoxide of iron, containing traces of phosphoric
acid and manganese - — - - - 18°04
Organic matter = - = - - - 12°36
Loss, chiefly water - - - - Ue 5)
100-00

The iron is here stated as protoxide, but if calculated as
peroxide, would amount to 16°69 per cent. Some of it cer-
tainly is in the latter form from the action of the air, and the
brown colour, and this diminishes the loss, but I have stated
it as protoxide, because I believe it to be in that state before
the air has access to it. ‘The presence of phosphoric acid,
which was easily detected in the oxide of iron, by the use of
molybdata of ammonia, is interesting. It is most probably
derived from the organic matter of the Diatomacee, but I am
not aware that its presence has been yet ‘observed in any in-
fusorial earth. Ihave not determined the proportion of phos-
phoric acid, which, although small, is appreciable. The earth
contains neither lime nor magnesia.

It is probable that this earth may be useful as a manure
from the finely divided silica, the organic matter, and the
phosphoric acid it contains. Professor Bailey ascribes the
fertility of certain districts in America to the abundance of
infusorial remains on the soil, so that the experiment is worth
trying.

98 GREGORY on Diatomaceous Earth.

I find I have omitted to notice that, besides the Diato-
maceous organisms, the Mull earth contains abundance of the
long spicules, and also of the gemmules of Sponyilla fluviatilis
and S. lacustris, also a considerable number of siliceous forms,
apparently Phytolitharia, more particularly Lithostylidium
clepsammedium, and similar forms. ‘There are also some
silicified forms much resembling certain deposits in the cuticle
of Graminee, &c., besides occasionally silicified pollen grains,
belonging both to grasses, and as I believe to Conifer. I have
also seen some fragments of woody fibre and cells, probably
silicified ; but I have not the means of determining with any
accuracy these various organisms. Probably many members
of the Society will be able easily to do this. I think I have
seen some forms which resembled very much the Desmi-
diaceze, such as Huastrum, Staurastrum, and Cosmarium; but
on these points I will not venture to assert anything, although,
as Desmidiacez occur in flint, and often contains a little
silica, this occurrence is possible.

In conclusion, even the imperfect examination to which
the Mull deposit has been subjected, proves it to be richer in
Diatomaceous species, and I think also in genera, than any
other known deposit, so far as I am acquainted with them.
I have heard that the deposit at Santa Fiora contains 39
species, and that found near Peterhead, and described by Dr.
Dickie, contains 40, but I know of no others which equal
these two, whereas in the Mull earth we have at least 60
species and 16 genera. ‘This will of course be interesting in
reference to the geographical distribution of fossil Diato-
macee, and I may add that Ehrenberg, who is preparing to
publish a great work on this part of the subject, has been
very much interested in the Mull earth, as being the first he
had been able to obtain from the Hebrides, and thus filling
up a great blank in his work. It is not, however, the first
that has been discovered in the Hebrides, as there is a Diato-
maceous earth at Raasay, also in the Hebrides. This I have
not yet examined, but I presume it has been described.

I beg to offer to the Society a few slides made, as I have
stated, from a specimen of only middling quality, such as
alone has been in my possession of late, and also a specimen
of earth, not yet examined, in its natural state, which may
possibly turn out good. I have added a portion of prepared
earth in water, which cannot be cleaned from quartz fragments,
but certainly contains a good many fine examples of the rare
and beautiful Pinnularia alpina. .

The subjoined figures are rough sketches of the doubtful

Grecory. 0% Diatomaceous Earth. | 99

form in the Mull deposit. They are represented with
a power of 400 diameters. I a :
find the length to vary from
1-470 to 1-600 of an inch.
There are, as Mr. Smith first
ascertained, 44 striz in 1-1000
of an inch. It always exhibits
the two notches towards the
ends of the plane or slightly
concave side. Fig. 1 is by far
the most usual form; fig. 2
is, however, not unfrequent.
The form is very abundant in
the Mull deposit, and I have only seen it in one other,
also from Scotland, namely in a slide labelled ‘“‘ From the
banks of the Spey,” which, J had from Mr. Topping:
Himantidium Arcus, which, when small, has some slight
resemblance to the above form, has only 22 strizin 1-1000 of
an inch and its striz are consequently, ceteris paribus, quite
easily seen, when those of the doubtful form cannot be made
out. Mr, Smith thinks its place must be near Hunotia Arcus,
Kiitzing—Navicula Arcus, Ehr.; but that it cannot be referred
to that species. Indeed it is only very immature specimens
of EH. Arcus (Kiitz.) that at all resemble this form, since
the mature /. Arcus (Kiitz.) has a bend or rounded angle in
the middle. The doubtful form may be an immature one,
but what is its aspect when mature ?

On the Binocular Microscope, and on Stereoscopic Pictures of
Microscopic Objects. By Professor C. Wueatstong, F.R.S.
Communicated by Dr. Lankester, F.R.S. (Read April 27,
1853.)

In Section 11 of my first Memoir on Binocular Vision, pub-
lished in the Philosophical Transactions for 1838, I have
alluded to the illusions to which microscopic observers are
liable, from their inability to judge correctly the relief of
objects when one eye only is employed. This indetermination
of the judgment exists whenever a shadowless object is re-
garded with a single eye. Frequently an elevation appears as
a depression, a cameo as an intaglio, a hollow pyramid (as a
crystal of muriate of soda) as a pyramid in relief, &c., and
vice versa; but this indecision is entirely removed when the
object is viewed with both eyes simultaneously. No mistake,
if the object be a near one, can then be made with regard to

t
%

100 Wueatstone on the Binocular Microscope, &c.

its relief; and the relative positions of every point, in depth
as well as in length and breadth, can be correctly determined.

The stereoscope affords a convincing proof that the two pro-
jections of an object presented to the two eyes, suggest the real
object far more effectively to the mind than a single projection to
one eye does; and those who have paid much attention to the ap-
pearance of binocular pictures in the stereoscope, will not have
failed to remark, that not only is double vision of importance
to enable us more accurately to judge of the relief of bodies,
but it also occasions us to perceive things which pass entirely
unnoticed when monocular pictures alone are regarded.

Fully impressed with these views, and convinced, from the
reasons above stated, that a binocular microscope would possess
great advantages over the present monocular instrument, I,
shortly after the publication of my first memoir, called the
attention both of Mr. Ross and Mr. Powell to this subject,
and strongly recommended them to make an instrument to
realize the anticipated effect ; their occupations, however, pre-
vented either of these artists from taking the matter up. The
year before last, previous to the publication of my second
memoir, I again urged Mr. Ross, and subsequently Mr. Beck,
to attempt its construction, and for a short time they interested
themselves in the matter, but ultimately relinquished it for
want of time, and in my opinion over-estimating the difficulties
of the undertaking.

It appears, however, from a communication in the ‘ Ame-
rican Journal of Science’ of January, 1853, which has been
reprinted in the last number of the ‘ Microscopical Journal,’ that
such an instrument has been actually constructed by Professor
J. L. Riddell of New Orleans, and the results expected have
been obtained. ‘The method Mr. Riddell employs is similar
to the one I recommended to Mr. Beck. After the rays from
the object pass through the compound object-glass in the usual
manner, he deflects them by means of a system of rectangular
prisms into two directions parallel to the original, and suff-
ciently separated for the images to be seen by each eye. As
in this arrangement there must be a considerable loss of light,
I have proposed another which will not have this disadvantage,
and which I will shortly submit to the Society.

A binocular microscope is, however, by no means a novelty,
and its invention dates nearly two centuries back. I have
found, in the library of the Royal Society, a work entitled
‘La Vision parfaite, ou les Concours des deux Axes de la
Vision, en un seul point de V’Objet. Par le P. Cherubin
d’ Orléans, Capucin” This work was published at Paris in
1677, and in it eight chapters and a plate are devoted to a

Wueatstone on the Binocular Microscope, &c. 101

minute description of the instrument, which he informs us he
constructed, and presented to the Dauphin. The following is
an extract from the Preface :—

“< Some years ago I resolved to effect what I had long before premedi-
tated, to make a microscope to see the smallest objects with the two eyes
conjointly ; and this project has succeeded even beyond my expectation,
with advantages above the single instrument so extraordinary, and so
surprising, that every intelligent person to whom I have shown the effect,
has assured me that inquiring philosophers will be highly pleased with
the communication. For this reason I have determined to make it the
principal subject of the present work.”

And the second part, which contains a description of the in-
strument, is thus headed :—

** Section the first, in which is taught the method of constructing a
newly-invented microscope to see the smallest objects very agreeably and
conveniently, represented entire to the two eyes conjointly, with a magni-
tude and distinctness which surpasses everything which has been hitherto
seen in this kind of instrument.”

In the Pere d’Orléans’ binocular microscope, two object-
glasses have their lateral portions cut away so as to allow of
close juxta-position, and these nearly semi-lenses are so
arranged, that their axes correspond with the two optic axes
passing through the tubes containing the eye-pieces.. The
author’s aim in its construction was solely the reinforcement
of the impression by presenting an image to each eye, for he
assumes, according to the then prevalent error, that vision by
the two organs conjointly is naturally and necessarily unique,
from the perfect conformity of all the homonymous parts of
the two images of the object on the two retine. The real ad-
vantage of such an instrument entirely escaped his attention ;
viz., that of presenting to the two eyes the two dissimilar
microscopic images of an object, under precisely the same cir-
cumstances as the two unlike images of any usual object is
presented to them when no instrument is employed, by which
simultaneous presentment the same accurate judgment as to
its real solid form, and the relative distances of all its points,
can be as readily determined in the former case as in the latter.

In the construction of a binocular microscope there is one
thing especially to be attended to—viz., that the images be both
direct, for in this case only a true stereoscopic representation
will be obtained. If the images, on the contrary, be inverted,
a pseudoscopic effect would be produced which will give a very
erroneous idea of the real form. The reason of these effects is
fully explained in Sections 5,10, 22, 23, of my Memoirs. The
reversal of the images by reflection from mirrors or reflecting
prisms, will produce the same result as to the stereoscopic and
pseudoscopic appearances as their inversion by lenses. The
binocular microscope constructed by the Pere d’Orleans was

SO anal ate

102 Wueatstone on the Binocular Microscope, &c.

pseudoscopic, though he describes one which, had it been
made, would have been stereoscopic; he was, however, quite
unaware that there would be any difference of this kind between
them. ‘The pseudoscopic effects when inverted images are
presented, and the natural appearances when erecting eye-
pieces are employed, have not escaped the observation of Mr.
Riddell.

Besides actual inspection by means of the binocular micro- |
scope, there is another way in which the advantages of bino-
cular vision may be applied to microscopic objects. The
beautiful specimens of photography, reproducing the highly
magnified images of objects, inserted in a recent number of
the Microscopic Journal, makes one regret that they were not
accompanied by their stereoscopic complements. A very
simple modification of the usual microscope would fit it for
producing the two pictures at the proper angles; all that is
necessary is to cause the tube of the microscope to move inde-
pendently of the fixed stand round an axis, the imaginary pro-
longation of which should pass through the object. A motion
of 15° would include every difference of relief which it would
be desirable to have, and it is indifferent in what direction this
motion is made in respect to the stand. ‘The pair of stereo-
scopic pictures may be obtained by a still simpler method,
which requires no alteration in the microscope ; the object
itself may be turned round on an imaginary axis within itself,
from 7° to 15°. But this method is inapplicable unless the
light be perfectly diffused and uniform so as to avoid all
shadows, the presence of which would give rise to false stereo-
scopic appearances. In the former case, where the object
remains stationary and the tube moves independently of the
frame, the arrangement of the light so as to cast single shadows
might be an advantage, and assist the visual judgment.

DESCRIPTION OF THE PLATES.

The letters throughout have the same signification :—a, trochal disc ;
b, body ; ¢, tail of peduncle; d, mouth; e, pharynx; f, “‘ yellow mass ;”
g, gizzard; h, “‘pancreatic sacs;” 7, rectum; #4, anus; J, ovary; m,
water-vessels ; n, ganglion; 0, ciliated sac; p, upper circlet of cilia; p/,
_ lower circlet of cilia; 7, vacuolar thickenings.

PLATE I.—JZLactrularia socialis.

mA
09

OMOIAD NBO De

. A single individual from the side.

Lateral view of the trochal disc.

. Trochal disc from above.

. Aperture of the mouth—ciliated sac and ganglion.

. Animal retracted.

. Armature of the gizzard, viewed laterally.

. Termination of a water-vessel in the trochal disc.

. Water-vessel much magnified, showing the long flickering cilium.

. A portion of the ovary much magnified, showing the germinal vesicles
with their spots scattered through its substance.

10, 11. Stages in the growth of the ovum.

12-18. Stages in the development of the embryo.

19, Spermatozoon ?

PLATE II.

20. A portion of the ovary undergoing the change into an ephippial ovum.

21, 22. Ephippial ova, the latter having its contents divided into two
portions.

23. Ephippial ovum burst.

24. Its contents.

25. Muscular fibre—relaxed, a; contracted, 0.

Melicerta ringens.

26. Viewed laterally.

27. From the ganglionic side.

28. From the mouth side.

29, Extremity of the calcar, showing its apparent closure and the bundle
of cilia.

Brachionus polyacanthus.

30. Viewed laterally.

31. From the mouth side.
32. From the ganglionic side.
33. From above.

Philodina, sp. ?

34. Trochal disc from above.
, laterally.
36. From the mouth side.
37. From the ganglionic side.

PLATE III.

The Diagrams illustrate Mr. Huxley’s paper of Adult Rotifera, and of
Larval Annelids and Echinoderms.
Fig.
1. Raphides from Cactus enneagonus, showing a nucleus surrounded by
concentric lamine.
2. The same, with irregular lamine.
3 & 4, The same, without concentric lamination.
5. Nuclei of raphides.
6. Separated crystals of compound raphides.

Trans ee FLT

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T Horley, del. Tuffen West ,sctilp Ford & West, Imp. 54) Hatton Garden.

LACINULARIA

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Trans. Soir Soe. PLM

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Pa ew ARIA BI MELICERTA, €C. BRACHIONUS.
Dy Poi ODINA.

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Lacinularia. Melrcerta Philodina Brachionis Stephanoceros

Larval
Annelids
& Echinoderms.

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DESCRIPTION OF PLATE IV.

On a Cyst upon the Olfactory Nerve of a Horse, by J. B. Simonds, Esq.
a
1. The cyst containing a crystal of oxalate of lime.—a, Bell-shaped spot
in interior of cyst.—b, A moveable mass of granular matter.

On the Development of Tubularia indivisa, by J. R. Mummery, Esq.
16, 17. Fully developed head of Tubularia indivisa, loaded ) repro-
ductive capsules.
13. Newly-formed head.
14, The same, showing arrangement of ovaries.

12. Internal surface of head (the oral tentacles removed), exhibiting
twelve lines radiating from base of cavity, and corresponding with
external ovaries.

15. Base of two marginal tentacles,

18. A group of reproductive capsules from the full-grown head, in several
co-existing stages of development.

2, 3, 4, 5, 6. Progress in the extrication of young Tubularia, at intervals
of one hour.

8. A young animal of the ellipsoidal form.
7a. Ditto, of the discoidal variety.
7s. The same, thirty-six hours after emerging from the capsule.
7c. The empty capsule.
10. The specimen, fig. 8—three days after—still free.
9. Ditto, on the fifth day, having affixed itself at base.

11. The young animal at the expiration of six weeks; the head having
now acquired a pale rose tint, and the peripheral tentacles increased
to sixteen.

DESCRIPTION OF PLATE V.

On the Structure and Development of Volvox globator, by Geo. Busk, Esq.

1.
7

3.

Embryo Volvox, in which the contents are divided into four segments.

Ditto, in which segmentation has proceeded to the formation of
numerous segments, each furnished with several amylaceous
spherules.

Ditto, after segmentation is completed, but before the appearance of
cilia.

3.* Portion of the edge of an embryo Volvox viewed in the equatorial

oa >

27.

plane, showing the cilia perforating the outer tunic, but not passing
beyond the external gelatinous (?) envelope.

. The same when tested by solution of iodine,
. Portion of the edge of mature Volvox (var. vulgaris) viewed in the

equatorial plane and representing three zoospores im situ. The
faint lines between indicate the limits of the gelatinous envelope
of each zoospore, the junctions of which are indicated by the
hexagonal areas of Mr, Williamson. (‘These intermediate lines have
been added to the figure since the original production of the paper.)

. Mature zoospores, undergoing “‘ deliquescence.”
. Zoospores in which the contractile vacuole is still present.

“Winter spores” of V. awreus. a, in the earlier state; 6, when
matured.

. Contents of mature winter spore, affected by solution of iodine.

a, amylaceous granules ; ; 5, yellow oil.

. More highly magnified view "of a winter spore compressed, to Sow

the double aoe.

. The same crushed, and treated with iodine and sulphuric acid.
. A portion of the edge, to show the granular fluid (as rendered so by

iodine) between the outer and inner tunics. a, granular fluid;
b, interior of spore.

. Portion of wall of Spheerosira Volvox. p
. Zoospores in different stages of development. a, one fully divided,

seen on the side; b, the same viewed from above ; c, one in which
segmentation has proceeded only to the second division.

Series of changes occurring in the hydropical condition of zoospores.

. More highly magnified view of the same—where there is apparently

a second coat in process of being thrown off from the central mass
of protoplasm.

twenty-four hours.

Fig. 22 shows the paral dropsy of the cell, but which did not
proceed further.

| A series of changes undergone by the same ZOOSpores in the course of

. Professor Williamson’s hexagonal areolation.
. Ditto under iodine.
. Appearance assumed by the zoospores in the early state, where, owing

to abundant nutrition, the quantity of protoplasm is very abundant.

This form gradually passes into the ordinary, and it is in this state

that the contractile spaces are most advantageously to be sought.
Shows the situation of the contractile vacuole in a connecting band.

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DESCRIPTION OF PLATE VI.

On the Structure of Volvox globator, by Professor W. C. Williamson.

The same letters of reference are employed throughout to indicate the
same structures.

Cells of the stellate var. of Volvow in different stages of the con-
traction of the protoplasmic threads. a, outer cell-wall; 5, pro-
toplasm ; e, connecting threads; g, cilia.

. Section of Volvox, with its ciliated parietal cells. /, vesicles in
which the ciliated gemme are developed. Two of the gemmzx
seen out of focus.

6. Young gemma ruptured by pressure. 06, detached protoplasms ;
J, vesicles within which the gemma is developed ; c, protoplasmic
membranes of three segments of the gemma. 0, granular and
mucilaginous matter escaping from the ruptured segments.

7. Portion of a Volvox mounted in glycerine and viewed obliquely.
a, cell-walls ; 6, protoplasms ; cc, protoplasmic membranes ; e, col-
lapsed connecting threads.

8. Similar cells, in which the protoplasmic membrane is more distended.
References as before.

9. Specimen in which the threads appear to traverse the intercellular
spaces. References as before.

10. Ordinary appearance of the var., with spherical protoplasms.

11: Specimen of the same mounted in glycerine.

12. Probable section of living Volvow. d, superficial pellicle.

13. Probable section of fig. 11.

1 | Sections of figs. 1-4, after being mounted in glycerine.

16. Detached cells.from the same, viewed superficially.
17. Similar specimen, in which the cells are invisible—the protoplasmic
membranes alone being seen.

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‘DESCRIPTION OF PLATE VIL.

; These Positive Photographs from Collodion Negatives, taken by
_ J. Delves, Esq., illustrate that gentleman’s, Mr. Shadbolt’s, and Mr.
& eae papers on Photography.
Fig.

ing Spimale and Trachem of the Siliswolin, magnified 60 diameters, exhi-
biting the elastic spiral fibre between the layers of the air vessels.

ze 2. Proboscis of the Fly, magnified 180 diameters, showing the divided
Bet absorbent tubes.

DESCRIPTION OF PLATE VIII.

On the Starch-granule, by G. Busk, Esq.

ig.
rE 2,3, 4,5. Various forms of starch-granules in ‘* Tous les mois”
Arrowroot.
6. Granules beginning to expand.
7, 8, 9. Farther progressive stages of expansion of the granule of ‘‘ Tous
les mois.”
10. Various forms of starch obtained from the Horse-chestnut (sculus
hippocastanum).
11, 12, 18. Granules of the same starch acted upon by sulphuric acid,

DESCRIPTION OF PLATE IX.
On Asteridia in Conferve, by the Rev. W. Smith.

1, Filament of Zygnema quininum, Ag., containing Asteridia in various

stages of development.
lie Scotian of Mesocarpus scalaris, Hass., var. 8, in conjugation, and

3 containing Asteridia.

4, Filament of Zygnema quadratum, Hass., in conga s

5. Filament of the same containing an Asteridiwm, and another a repro-
ductive spore.

6. Filament of the same, showing a double mode of conjugation in the
same species.

On a Fungus in an Oak Tree, by Prof. E. J. Quekett.
7. A portion of an oak tree, showing a fungus and masses of crystals,
in situ.
8. Fungus magnified 150 diameters.
9. Large crystal, having fungi in its interior.
10. A portion of fungus seen within a crystal.

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DESCRIPTION OF PLATE X.
Fig.
1. Lateral aspect of the Faujasina. Magnified 30 diameters.
2. Superficial section of the flat base of the shell. Mag. 60 diameters.
3. Horizontal section parallel to the last, across the points b 0, in fig. 1.

Mag. 60 diameters.
. Horizontal section across the points ¢ c in fig. 1. Mag. 60 diameters.
. Vertical section across the points dd in fig. 1. Mag. 60 diameters.
_ 6. Superficial section from the oblique side of the shell. Mag. 80 dia-
meters.

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INDEX TO TRANSACTIONS.

VOLUME I.

A.

Aloe verrucosa, raphides in, 21.

Amphistegina, 87.

Asteridia, in Alge, Rev. W. Smith
on, 68.

B.

Beale, Dr. L., analysis of raphides of
Cactus enneagonus, 25.

Binocular microscope, Prof. Wheat-
stone, 99.

Brachionus, 8.

Busk, G., on the structure and de-
velopment of Volvox globator and
its relations to other unicellular
plants, 31.

on some observations on the
structure of the starch granule, 58,

C.

Cactus enneagonus, Quekett on ra-

phides of, 20.
» senilis, Quekett on raphides

of, 22.

Chara vulgaris, 21.

Cladophora glomerata, 21.

Cocconema lanceolatum, 21.

Cordylophora lacustris, 21.

Cyst, membranous, containing a crys-

tal of oxalate of lime, on the olfac- |

tory nerve of a horse, J. B. Simonds
on, 26.

D.

Delves, Joseph, on the application of
photography to the representation
of microscopic objects, 57.

Diatomaceous earth found in the
Island of Mrll, Prof. W. Gregory,
9z.

K.

Eleagnus angustifolia, raphides in, 22.
Epithemia turgida, 95.
Eunotia Triodon, 95.

», Pentodon, 95.

ge baorda, 95.

F.

Fauwjasina, minute structure of, by
Prof. Williamson, 87.
Floscularia, vibrating membranes in,

3.

Fresh-water Alge, stellate bodies oc-
curring in the cells of, Rev.W.Smith
on, 68.

G.

Gosse, P. H., on water vascular sys-
tem in WVotommata aurita, 5.

Gregory, Prof. W., on Diatomaceous
earth found in the Island of Mull,
92.

H,

Huxley, T. H., on Zacinularia so-
cialis, 1.
Hydrodictyon utriculatum,

amyla-
ceous corpuscles of, 67.

K.

Kolliker on division of the yolk in
Megalotrocha, 11.

L.

Lacinularia socialis, anatomy and
physiology of, by T. H. Huxley,
LR sino)

Leydig, Anatomie u. Entwick.-gesch.
d. Lacinularia socialis, &c., 2, 8, 12.

Lyngbya floceosa, 71.

M.

Megalotrocha, 1, 12.

Melicerta, 2.

Merulius lachrymans, 74.

Mesostomum, 7.

Mesocarpus scalaris, 71.

Mummery, I. R., on the development
of Tubularia tndivisa, 28.

Mull earth, 95.

Index to Transactions.

N.

Naviculacee, 93.
Notommata aurita, teeth of, 4.
os water vascular sys-
tem in, P. H. Gosse on, 5.
NNonionina, 87. *

N.

Opuntia, raphides in, 21.

P;

Philodina, 17.

Photography, on the application of, to
the representation of microscopic
objects, by J. Delves, 57.

Polyzoa and Rotifera, analogy be-
tween, 16.

Potatoe, amylum grains of, 62.

Polystomella crispa, 87.

Q.

Quekett, on the structure of the ra-
phides of Cactus enneayonus, 20.
+3 on the presence of a Fungus
and of masses of crystalline matter
in the interior of a living oak tree,
72,

R.
Raphides, Quekett on, of various
plants, 20.
Rhubarb, raphides in, 21.
S.
Scilla maritima, raphides of, 21.

Simonds, J. B., on a membranous cell
or cyst upon the olfactory nerve of

a horse, coutaining a large crystal

of oxalate of lime, 26.

Smith, Rev. W., on the Asteridiz or
stellate bodies occurring in the cells
of Fresh-water Alge, 68.

Spheroplea crispa, 21.

Spherosira Volvor, 32, 39.

Spongilla fluviatilis, 21.

Starch, granule, observations on the
structure of, by G. Busk, 58.

Stephanoceros, 4.

Surirella ovata, 21.

Synedra fasciculata, 21.

T.
Tous le mois, starch of, 65, 66.
Truncatulina tuberculata, 87.
Tubularia indivisa, development of

by I. R. Mummery, 28.
Turbellaria, 16.

U.

Udekem, on the water vascular sys-
tem of Lacinularia, 6.

V.

Volvox globator, Busk, G., on the struc-
ture and development of, 31.

i further elucidations of
the structure of, by Prof. W. C. Wil-
liamson, 45.

V. aureus, 40.
V. stellatus, 40.

W.

Williamson, Prof. W. C., further eluci-
dations of the structure of Volvor
globator, 45. .

Williamson, Prof. W. C., on the mi-
nute structure of Fawasina,

Wheatstone, Prof., on the binocular
microscope and stereoscopic pic-
tures of microscopic objects, 99.

Z.

Zygnema quadratum, 70.
>» «= quintnum, 70.

.

TRANSACTIONS

OF THE

MICROSCOPICAL SOCIETY

LONDON.

NEW SERIES:

Ww

VOLUME II,

LONDON:
SAMUEL HIGHLEY, 32, FLEET STREET.
1854.

LONDON : PRINTED BY W. CLOWES AND SONS, STAMFORD STREET.

TRANSACTIONS

OF THE

MICROSCOPICAL SOCIETY

OF

LONDON.

On the Application of Brnocutar Vision to the Microscope. By
F. H. Wenuam. (Read May 25, 1853.)

On viewing objects by the unassisted eyesight there are two
conditions which enable us to appreciate or judge their various
distances. Firstly, the object is observed by each eye from
a separate point of view, and the consequent difference of
outline, light, and shade between the images formed on each
retina allows us to form an accurate idea of their various
sizes and positions. ‘The angle of stereoscopic vision has been
stated somewhat definitely to be about 18 degrees, but this
must be subject to considerable variations, as whether the ob-
server is long or short-sighted, the difference of distance
between the eyes, and also the bulk, form, and position of the
object. I may state that I have obtained a very good perspec-
tive of minute objects when the angle of vision has exceeded
50 degrees.

If we perforate a card with a pin, and examine the articles
in a room illuminated by candle-light, with one eye looking
through this aperture, we shall be able to judge of distance
only from the relative intensity with which the objects are
illuminated, the nearest receiving and giving off the greatest
quantity of light, and the farthest being in comparative darkness.

I make these preliminary observations because, in viewing
the greatest portion of objects under the microscope, the con-
ditions here referred to, which give us the faculty of judging
of bulk and distance, do not exist in the same degree, if at
all. In the first place, in viewing an object, as a transparency,
with a single lens of short focus, we see it under such circum-
stances as seldom happen to such surrounding objects as come
under our daily observation, and in the illumination of trans-
parent objects by direct transmitted light, the effect is the
reverse of that which is necessary for us to Judge of distance

VOL. I,

Z WenuamM on Binocular Vision.

by the relative intensity of the light, for that portion of the
object farthest from the lens will receive the greatest share.
This objection may probably be removed by a different sys-
tem of illumination, but of this I shall treat hereafter. If the
single lens is provided with a proper stop, what is known as
the angle of aperture will be so exceedingly small that a series
of uniform opaque particles lying behind each other in an
object will be only seen by the direct light that they intercept,
and the underlying ones will be invisible. These are the
reasons why most microscopic objects, which we know must
have a visible thickness, appear so perfectly thin, that we
might almost imagine that they were painted on the glass
slide upon which they are mounted. This illusion may be
attributed to the natural effects of monocular vision, and in
this case the only remedy is to view the object from different
points at the same time with each eye, under equal magnify-
ing power. I shall now enter into various methods of effect-
ing this. One of the most simple and obvious is to employ
two lenses, one to each eye, only differing from an ordinary
pair of spectacles in the foci being shorter and the optic axes
converging till the points where the foci intersect become
coincident.

Binocular vision may also be obtained through a single
lens, if the diameter is sufficiently large to allow both eyes to
see through it at the same time as in the common reading-
glass. In these instances we cannot well use glasses of shorter
focus than four or five inches; and in cases where higher
magnifying powers are required it becomes necessary to adopt
some method which shall produce the effect of bringing the
two eyes proportionately closer together, to suit the diminished
diameter and shorter focus of the lens. This may be accom-
plished by means of a system of four plane reflectors, inclined
at an angle of 45 degrees, and fixed behind the lens in a
line at right angles to its axis, or else by four rectangular
prisms in the same position; both these can be made
to adjust to suit the
diameters of various
3 lenses and difference of
; | Meee) §€6 clistance between the
“LLL, ESSsanv” eyes.

2 The arrangement that
/ I have tried for lenses
of short focus is repre-
sented by fig. 1: aa is
a plano-convex lens, be-
hind which is placed the usual stop) b. c¢ ¢ are two rhomboidal

Fig. 1.

Wenuam on Binocular Vision. | 3

prisms of glass, with the reflecting ends inclined at an angle
of 45 degrees. All the four surfaces of both prisms should
be well polished, and their combined length when placed
together should be such that the distance between the centres
of the external diagonal reflecting planes should be the same
as that between the eyes. I prefer the two solid prisms to a
combination of four rectangular ones, as there is less loss of
light, and error arising from external reflection. This com-
bination makes a remarkably fine hand magnifier, giving such
a depth and substance to objects as cannot be obtained with a
single eye; the field of view is also large, as we are able to
see the object obliquely through the lens. For lenses of low
power, as from one to two inches focus, the prisms would
require to be separated to some extent, or we should not ob-
tain a sufficient angle for stereoscopic vision; in fact, we
must consider this merely as a method of bringing the eyes
closer together, that we may be enabled to see through a lens
of small diameter with both of them at the same time, in a
similar way as with the ordinary reading-glass before re-
ferred to.

On looking through the prisms, fig. 1, without the magni-
fier, a singular illusion is produced, for the vision with the
two eyes is brought so nearly to a state of parallelism that
they are in effect blended into one, and we so far lose the
power of appreciating distance, that we appear able to grasp
objects several feet away from us, as the deceptions arising
from monocular vision are increased by seeing with the two
eyes from the same position as with one.

In obtaining binocular vision with the compound achromatic
microscope, in its complete acting state, there are far greater
practical difficulties to contend against, and which it is highly
important to overcome, in order to correct some of the false
appearances, arising from what is considered the very perfec-
tion of the instrument. All the object-glasses from the one
inch upwards are possessed of considerable angular aperture,
consequently images of the object are obtained from a differ-
ent point of view, with the two opposite extremes of the
margin of the cone of rays; and the resulting effect is, that
there are a number of dissimilar perspectives of the object, all
blended together upon the single retina at once. For this
reason, if the object has any considerable bulk, we shall have
a more accurate notion of its form by reducing the aperture of
the object-glass.

Select any object lying in an inclined position, and place it
in the centre of the field of view of the microscope, then,
with a card held close to the object-glass, stop off alternately

b

4 Wenuam on Binocular Vision. -

the right or left hand portion of the front lens, it will be seen:

that, during each alternate change, certain parts of the object
will alter in their rela-
Ye. tive position. To il-
te lustrate this, figs. 2
and 3 are enlarged
drawings of a portion
of the egg of the com-
mon bed-bug (Cimex
lecticularis), the oper-
culum which covers the
orifice having been
forced off at the time
the young was hatched. The figures exactly represent the
two positions that the inclined orifice will occupy when the
right and left hand portions of the object-glass are stopped
off. It was illuminated as an opaque object, and drawn
under a two-thirds object-glass of about 28° of aperture.

If this experiment is repeated, by holding the card over
the eye-piece, and stopping off alternately the right and left
half of the ultimate emergent pencil, exactly the same changes
and appearances will be observed in the object under view.
The two different images thus produced are just such as are
required for obtaining stereoscopic vision. It is therefore
evident, that if, instead of bringing them confusedly together
into one eye, we can separate them, so as to bring figs. 2 and
3 into the left and right eye, in the combined effect of the two
projections we shall obtain all that is necessary to enable us
to form a correct judgment of the solidity and distances of the
various parts of the object.

I shall. now explain some plans for effecting this. The
most obvious method is to have two microscopes placed side
by side, and converging towards the object, each tube to be
furnished with a similar objective and eye-piece. For very
low powers this would, no doubt, be the most perfect form of
binocular microscope, but it is liable to objection, firstly, on
account. of its expense, and, secondly, from the difficulty, if
not impossibility, of using the higher powers. I do not think
that it would be practicable to use anything beyond the half-
inch object-glass; but I believe where vision is assisted by
the use of both eyes together, it would be of advantage to
employ objectives of smaller angular aperture, in this case, the
focus would then fall at a greater distance from the front lens.
I should also mention that a microscope of this description
would require the two tubes to be placed at a different angle
of convergence for every pair of object-glasses employed, of
either longer or shorter focus.

Bigs 1b te Fig. 2.

OS

TT

WenuaM on Binocular Vision. 5

It has also been proposed to bisect the whole combination,
of which our best objectives are composed, and separate the
semi-lenses a sufficient distance asunder to obtain the effect
of stereoscopic vision, each half being made to serve the
purpose of a distinct combination; but this, I believe, would
not answer at all, for if we escaped the total destruction of
the object-glass during the operation of sawing it through, we
should render it useless for all the ordinary purposes of inves-
tigation, and also because any separation of the semi-lenses
is quite unnecessary; for the angle of aperture of all the
object-glasses by our best makers now exceeds that which is
requisite for obtaining stereoscopic vision; and the methods
that I have now to explain refer to the principle of obtaining
two images of the object through the same object-glass, which
is in all cases of the usual construction.

In the last ‘Quarterly Journal of Microscopical Science’
there appeared a notice of a binocular microscope by J. L. Rid-
dell, from Silliman’s Journal.
According to his description,
fig. 4 will represent the ar-
rangement ; a is the objective
provided at the back with the
usual stops. The pencil of
rays emergent from the ob-
ject- glass is bisected and re-
flected in opposite directions,
by means of the internal
surfaces of the rectangular
prisms 6 b, which surfaces
are inclined at an angle of
45°. The rays are again re-
flected in a vertical direction,
by means of two similar
prisms, cc, the distance be-
tween which must be regu-
lated by the position of the
eyes. The last prisms must
be placed upon a lower level,
as from the direction in which
the rays are incident upon )
the first reflecting surfaces of the prisms b b, they have a down-
ward tendency. The rays, after crossing each other, are received
by two Huygenian eye-pieces, dd. In the diagram I have
shown the prisms no larger than necessary for collecting all
the rays from any of the object-glasses to be used; but it
must be evident that Mr. Riddell makes use of prisms of

b

6 WenuaAM on Binocular Vision.

a larger size, as he states that “The outer prisms can’ be
cemented to the inner by Canada balsam.” This amounts
to the same thing as using a pair of prisms of solid glass,
such as is represented by cc, fig. 1. I have carefully tried
both of these methods, and find that the prisms alter the
chromatic correction of the object-glass, and also materially
injure the definition; for in making arrangements of prisms
of this description we must always bear in mind that they
produce a similar kind of aberration as a piece of glass of the
same thickness as the distance which the ray passes through,

Fig. 5. both before and after its reflection. There
is also great difficulty in getting a per-
fectly flat surface to the small reflecting
planes. All these defects will be greatly
magnified by the eye-piece.

I have also tried what effect could be
produced by means of plane reflectors, as
Mr. Riddell says, “I use, for lightness
and economy, four pieces of common
looking-glass instead of prisms.” My
experiment was not tried with common
looking-glass, but with thin microscopic
covering-glass, silvered at the back. The
definition with the lower powers was to-
lerably good, but the loss cf light very
great.

In order to remove the illusion of ele-
vations appearing as depressions, Mr.
Riddell proposes the “additional use of
erecting eye-pieces ;” but I am afraid that
when the microscope is taxed with this
| addition, the loss of light and defining
power will become very great, and that
even easy test-objects will appear so ob-
scure as to preclude all hope of our
making any additional discovery relative
to their structure.

I must remark, that I have made these
last observations and experiments merely
for the sake of arriving at the truth, and
not with the view of detracting in the
slightest degree from the merits of Mr.
Riddell’s invention; for very great credit
is no doubt due to him for leading the
way to the practical application of a principle, in the absence
of which the microscope still remains an imperfect instru-
ment; and, for my own part, I may, in all probability, shortly

WenuaM on Binocular Vision. 7

see the day when my own designs for effecting the same end
may be rendered obsolete by the march of improvement.

In the plan just referred to, the error arising from the
leneth or thickness of the prisms may
be diminished by making the two mi-
croscope bodies converge towards b 6,
fig. 3, and adopting two rectangular
prisms with the reflecting surfaces at
the proper inclination for directing the
rays of light from the object-glass, up
the centre of each tube: by this means _
we can much reduce the substance of
glass that the rays will have to pass
through.

Figs. 5 and 6 represent another
method that I have contrived for using
only two prisms, which can be made of
the smallest possible size, and also at
the same time do away with one re-
flecting surface, which is one of the
principal sources of error. Fig. 5 is
the plan, and fig. 6 the elevation. a,
fic. 6, is the object-glass, over which
are two right-angled prisms bb, placed
side by side with the reflecting sur-
faces, at an angle of 45°. ce, fig. 5,
are two Huygenian eye-pieces, placed
a sufficient distance asunder to suit
the eyes, and converging towards the
vertical axis of the object-glass. The
contact sides of the prisms must be
equally ground away, till their two
emergent surfaces are in a plane at
right angles to the axes of their respec-
tive eye-pieces. This method in-
volves the necessity of having the
object-glass at right angles to the :
two bodies of the microscope, and is therefore just suited to
some of the foreign form of stands, but is of course inap-
plicable to the English ones, unless, indeed, we mount the
bodies after our usual fashion, and allow the object-glass to
point upwards in an inclined direction, and pass through the
bottom of a stage, on the upper surface of which the objects
can be placed, and which surface should be parallel to the
axes of the bodies. This would give great facility for direct
illumination ; for whether we used a superposed achromatic
condenser or not, we should not require a mirror either by

Fig. 6.

8 WenuaM on Binocular Vision.

day or candle-light. I have not yet tried this arrangement of
prisms, but intend to do so, as I have a favourable opinion of

the method, although the one next to be described is pro-

bably better. .

If we consider the relative position of the two reflecting
surfaces of the prisms 56, figs. 5 and 6, they will form the
same angle represented by the
es top line of fig. 7. It is there-

Vig 7 fore evident, that if a rectan-
gular plate of speculum metal is

KAAKRF>RDDHRKRC Souta and oldie so as to
form two reflecting facets in-
clined to each other at the re-
quired angle, as represented by fig. 7; and this being placed
at an angle of 45°, with the division of the facets intersecting
the axis of the object-glass, we shall divide the rays, and
reflect them horizontally, just in the same way as represented
in figs. 5 and 6, merely by means of one single reflection.
Any other direction than a right angle, with respect to the
axis of the object-glass, may of course be given to the rays,
by inclining the reflector more or less. From the simplicity
of this contrivance, and the facility with which it may be
constructed, I shall take an early opportunity of giving it a
trial. The only question I have is, whether a material may
not be found that will reflect more light than even speculum
metal: I have heard an alloy of cast-steel and platinum well
spoken of, but have never seen any of it.

In considering the aberrations which the thickness of glass
contained in the reflecting prisms must inevitably produce
when placed immediately behind the object-glass, it occurred
to me, that if the same prisms were placed close to the top lens
of the eye-piece, these errors, not being magnified, would be
less sensibly felt.

I have before mentioned, that the final image of an object,
when it leaves the eye-piece, is compounded of several different
images or perspectives of the object, all blended together,
and which are as equally capable of separation there as be-
hind the object-glass itself, as exemplified by figs. 2 and 3,
which bear exactly the same appearance when under view,
with the alternate sides of either the object-glass or eye-piece
stopped off.

Fig. 8 represents the methods that I have contrived for ob-
taining the effect of bringing the two eyes sufficiently close to
each other to enable them both to see through the same eye-
plece together. aaa are rays converging from the field lens
of the eye-piece. After passing the eye lens b, if not inter-
cepted, they would come to a focus at c, but they are arrested

ee

WennaM on Binocular Vision. 9

by the inclined surfaces d d, of two solid glass prisms. From
the refraction of the under incident surface of the prisms the
focus of the eye-
plece becomes
elongated, and
falls within the
substance of the
glass at e. The
rays then diverge,
and, after being
reflected by the
second inclined
surface f, emerge from the upper side of the prism, when
their course is rendered still more divergent, as shown by the
figure. The reflecting angle that I have given to the prisms
was 471°. I also find it is requisite to grind away the contact
edges of the prisms as represented, as it prevents the extreme
margins of the reflecting surfaces from coming into operation,
which can seldom be made very perfect.

The definition with these prisms is good, but they are
liable to objection, on account of the extremely small portion
of the field of view that they take in, and which arises from
the distance that the eyes are of necessity placed beyond the
focus of the eye-piece, where the rays being divergent, the
pupil of the eye is incapable of taking them all in; also there
is great nicety required in the length of the prisms, which
must differ for nearly every different observer.

I have constructed an adjusting binocular eye-piece, not
differing in principle from the last. The first reflection is
performed by means of a triangular steel prism, with the two
inclined facets very highly polished; this is represented by
the dotted outline gg, fig.8. The rays, after having been
reflected at right angles, are taken up by two rectangular
glass prisms, shown by the dotted lines at ff.

The loss of light in this is much greater than in the former
instance, and the ficld of view more contracted; for the rays
from the eye-piece, after being reflected from the surface of
the steel prism, fall to their natural focal distance, instead of
being elongated, as in the solid prism, consequently the eye is
still further removed from the focus. I had chosen hard steel
for the reflector, on account of the property this material pos-
sesses, of allowing the figure of a small flat surface to be
retained, or even perfected, during the operation of polishing.
I have also tried a combination of prisms over the field-glass,
using two eye lenses, but with no good result.

The best effect that I have yet produced in the way of

Fig. 8.

10 WenuaM on Binocular Vision.

binocular vision applied to the microscope, is that next to be
described, in which I have altogether dispensed with reflecting
surfaces, merely using three refracting prisms, which, when
placed together, are per-
fectly achromatic. aa, fig. 9,
is a single prism of dense
flint glass, with the three
surfaces well polished. 66
are two prisms of crown
glass, of half the length of
the under flint prism, to the
upper inclines of which they
are cemented with Canada balsam. The angle of inclina-
tion to be given to the prisms must depend upon the dispersive
power of the flint and crown glass employed. In the combina-
tion that I have worked out, I have used, for the sake of sim-
plicity, some flint and crown that Mr. Smith kindly furnished
me with, in which the dispersive powers are exactly as two to
one, consequently I have had to make the angle of the crown
just double that of the flint, in order to obtain perfect achro-
matism, The refractive power of each must also be known,
that we may determine the angles of the prisms suitable for
refracting the rays from the object-glass into the two eyes, at
a distance of nine inches. cc, fig. 9, represents a ray of light
incident at right angles upon the under surface of the flint
prism. On leaving the second surface and entering the
crown prism it is slightly bent.inwards, and on finally emerg-
ing it is refracted outwards, in the direction required.

On looking through this prism I could not discover the
slightest colour or distortion ; itis almost like looking through
a piece of plain glass, and the loss of light is so inappreciable,
that it is difficult to distinguish any difference between an
object and its refracted image.

The base of the compound prism should not be larger than
is sufficient to cover the stop of the lowest object-glass, in
order that they may be made very thin.

The method of applying the prism to the binocular micro-
scope is shown by fig. 10. aa is the object-glass, b the prism,
placed as close behind it as the fittings will admit. The
prism is set in an aperture ina flat disc of brass, which has
an horizontal play in every direction, in order that it may be
adjusted and fixed in such a position that the junction of the
prisms may bisect the rays from the object-glass, and at the
same time be at right angles to the transverse centres of the
eye-pieces.,

cc are the two bodies of the microscope, provided with

Fig. 9.

J is

Wennam on Binocular Vision. 11

draw tubes and the usual eye-pieces, dd. The distance between
them should be rather less than the average distance asunder
of the eyes, and in cases where
these are very wide apart we can
pull out the draw tubes, which will
increase the distance between the
eye-pieces.

With this apparatus I obtain the
whole of the field of view in each eye,
which circumstance I was not pre-
pared to expect, as this must in
some measure depend upon the cor-
rection of the oblique pencils of the
object-glass, for we cannot expect
to look obliquely through the ob-
jective of a compound achromatic
microscope in the same way as in
the single lens arrangement, fig. 1,
but can only avail ourselves of such
oblique pencils of rays as are cor-
rected for passing through the axis
of the microscope. The arrange-
ment represented by fig. 10 certainly
gives a larger and better field than
any other that I have yet tried; and
on examining a globule of mercury
I could not discover any aberration or inward or outward
coma when viewed by the eyes, either separately or together.
I should here mention that the same illusion is occasionally
produced in the appearance of some objects with the instru-
ment last described, as mentioned by Mr. Riddell, the vision
being to some eyes pseudoscopic, or projections appearing as
depressions, et vice versa. Probably habit would enable us to
judge of their true form without our being under the necessity
of resorting to a special expedient for the removal of the de-
ception.

‘T have not yet tried a binucular polariscope applied to this
instrument, but I have reason to expect some curious effects
from it.

I have thus far announced the progress of my experiments
towards the attainment of complete binocular vision with the
microscope, and | cannot too strongly insist on the importance
of striving to arrive at a perfect result, particularly with the
highest powers, for I feel convinced that it will be the means
of settling many disputed points of structure. Whether it will
require objectives of a peculiar construction I am not at present
_ able to determine, but I may observe that the high power

Fig. 10.

12 WenuaM on Binocular Vision.

object-glasses, as now constructed, are best suited for viewing
very thin objects. We obtain far more pleasant vision of
bulk and depth with a smaller aperture. I have no doubt
that the defects of the larger aperture arise from the confused
medley of stereoscopic images blended together in one eye,
and which confusion must increase with increase of aperture ;
but if, on the other hand, we can divide these images between
both eyes, then I admit that the aperture cannot be too great,
as the largest portion of microscopic objects, from the way in
which they are mounted, would be all the better shown under
an exaggerated perspective, if I may so express it.

The binocular microscope has already explained to me
some of the false appearances arising from oblique illumina-
tion. I refer particularly to what is known as the diffracting
spectrum ; for example, if we illuminate the Podura by very
oblique light, we see a kind of overlying shadow, upon
which the markings of the scale are also visible. As I can-
not reconcile this appearance to the known laws of the dif-
fraction of light, I think that it is miscalled, and appre-
hend that the phenomenon merely arises from the oblique light
illuminating one of the perspective images partly as an
opaque, and the other as a transparent object, and that they are,
consequently, so far separated as to give the appearance of a
double image.

In illuminating objects under the binocular microscope with
the ordinary concave mirror some management is required in
order to get both images equally intense, for we can readily
get one brilliantly illuminated, while the other is in compara-
tive darkness, appearing on a black ground almost as an
opaque object, exactly resembling in their combined effect on
the eyes what is known as the diffracting spectrum. It also
occasionally happens that the angle of light from the mirror
is not sufficient to illuminate both images at the same time.
These appearances lead me to conjecture that the mstrument
will require a particular kind of illumination, but I am hardly
yet in a position to express a decided opinion on the subject,
but will investigate the matter shortly.

This is the sum and substance of my present experience
with respect to binocular vision applied to the microscope,
and I do not think that mere enthusiasm has led me to over-
rate the importance of the subject, but hope that what has
already been done is only the commencement of a new era in
the advancement of this useful and important instrument. I
believe that there is yet much to be looked for in the way of
improvement by the investigation of unexplored optical com-
binations and principles.

Wennam on Binocular Vision. | 13

- In conclusion I must express my thanks to Messrs. Smith
and Beck for the prompt assistance that they have afforded
me in the construction of the instrument, and also for the
free use of such apparatus, selected from their stock, as might
be useful to me in conducting my experiments.

A Short Description of some New Forms of Diaromacrx from
Port Natal. By Geo. Suappotr. (Read May 25, 1853.)

THE constantly increasing interest evinced in the examination
of the elegant forms of the Diatomacee has recently received
an additional impetus from Messrs. Smith and Beck’s publi-
cation of the first volume of the long expected ‘Synopsis of
the British Species,’ by the Rev. W. Smith, F.L.S.

A work of the kind alluded to will supply a want that has
been much felt by microscopists, both as a record of what
has already been accomplished in this branch of study, and
also as a foundation for a general system of classification and
nomenclature, for not 6nly is the latter in the most deplorable
state of confusion, but by far the greater number of the foreign
species are only capable of being referred to by their “ local
habitation,’ being destitute of the other appendage generally
considered so necessary. |

Under these circumstances I propose conferring a provi-
sional name on such new species as [am about to describe,
trusting to the indulgence of any prior claimant to this right,
whom I may unintentionally supplant, and promising to with-
draw such name on cause being shown.

About twelve or fifteen months back I was supplied, by the
kindness of Mr. Geo. Busk, with a gathering of Diatomacez
from ‘ Port Natal” so rich that I shall not attempt to give a
detailed account of the forms already known, but, merely
noticing a few of the most prominent of these, describe more
particularly those species that are, so far as [ am aware,
entirely new, endeavouring by the respective designations to
recall them to the mind, by fixing upon some prominent
peculiarity of appearance in each as the foundation for such
distinction.

From the prevalence of certain forms (although I am not at
all acquainted with the facts of the case) I should be inclined
to pronounce the locality whence they are derived as subject
to marine influence, and at the same time probably not far
from the mouth of some river, and it is also evident that the
specimens are undoubtedly recent.

Mixed with the Diatomee are some other bodies, which
are scarcely capable of being classed with them, although, like

14 SHADBOLT on New Forms of Diatomacee.

the spicula of many of the sponges (of which there is a
goodly proportion), they are of a siliceous character, such
as the Dictyocha, and also a form to which my attention was
directed by Mr. Busk, and which I purpose identifying by the
name of Bacteriastrum, from Baxrngia, a stick, and Aorgov, a
star.

By the kind assistance of another of our members, Mr.
Capron, I am enabled to lay before you drawings of these
most interesting bodies (of which may he distinguished three
species), as also of most of the other novelties.

From the tenuity of their structure the various Bacteriastra
are better observed without being mounted in balsam ; they
consist of a central irregular annular portion (not unlike the
connecting membrane which may be observed in the Diatomee
during self-division), surrounded by from eight to twelve rays,
each many times longer than the diameter of the central por-
tion, and the construction of these rays affords a good specific
distinction, viz. lst, B. furcatum (fig. 1), the marginal rays
forked ; 2nd, B. curvatum (fig. 2), marginal rays entire and
curved in one direction; 3rd, B. nodulosum, marginal rays
entire, straight, and covered with small protuberances like a
knotted stick. This last species is by far the most rare.”

A form tolerably abundant and quite distinct from anything
I have ever met with from any other locality I propose to call
Euphyllodium, from ev, and @vAdaov, having somewhat the
outline of a spathulate leaf (fig. 3). It 1s characterised as
follows: viz. valve symmetrical, convex, divided by a median
rectilinear rib, reticulations of an irregular oblong form, dis-
posed in regular and elegant curves around centres formed by
the terminations of the median rib. I have noticed but one
species, which I have called C. spathulatum. There was at
first some doubt in my mind whether this might not belong
to the genus Cocconeis, but the very distinct appearance of the
median line, and the absence of anything that could possibly
represent the inferior valve, which in the latter genus is
generally (I believe always) somewhat different from the
superior one, and likewise the marked character of the outline,
satisfied me that this supposition was incorrect. It is not
unlike the aspect of the genus Podosphenia, but here again
there are differences so distinct as to satisfy me that it cannot
be referred to it with propriety; for instance, there is no re-
flexure of the valve, and the markings are not moniliform
striz, but rather tessellate in character.

* Since writing the above, I have made out most unquestionably that
this pseudo-annular portion is a distinct cell, and not a mere annulus.

Srapsott on New Forms of Diatomacee. 15

Of the genus Triceratium there are no less than five new
species, one old, and one doubtful, making seven in all.

The first I shall notice is of moderate size, and is distin-
guished by peculiarly delicate markings somewhat obscurely
disposed about three equidistant pseudo-nuclei— Tr. sculptum
(fig. 4).

Next we have one in which the markings appear like
minute dots, closely crowded together, but disposed in a very
regular manner from the axis of the valve; this is about the
same size as the preceding, but the outline differs materially,
each margin being arcuate with the concave surface outwards
— Tr. arcuatum (fig. 5).

Another species of medium size is in form nearly the con-
verse of the preceding, the margin being so inflated as to cause
the triangular outline to approach that of the circle; hence
Tr. orbiculatum as its specific designation (fig. 6). This
species exhibits a structure similar to that of Coscinodiscus
radiatus: the reticulations, however, are not so regularly
hexagonal, but they are largest at the centre, and diminish
in size gradually towards the margin of the valves.

- | have noticed also a single specimen of what appears to
be Tr. alternans, but, as it presents only its front view, it is
difficult to determine.

The next I shall allude to is, however, the most important,
being very remarkable and especially interesting from the
front view exhibiting the disposition of the horn-like append-
ages (figs. 7a@ and 75) and the mode of dividing. On the
lateral view of the valves the most striking peculiarity is a
sort of twistedness in the angles (fig. 7a), which is very
marked: the specific name proposed is to note this fact, viz.
Tr. contortum.

The surface of each valve is adorned with short spines
arranged in a tri-radiate double row, and at the termination
of each double row is one very long one, being about one-
third of the length of aside of the valve. These long spines
are independent of and placed nearer to the axis than the
horn-like processes from which the genus derives its name.
Fig. 7b shows a specimen undergoing self-division.

_ Another new species, much smaller than the last, is charac-
terized by the reticulations being coarse and irregular in form,
and the horns very large as compared with the size of the
valve— Tr. crassum.

Another species is, I believe, a variety only of the T. favus,
which has been called gibbosus.

The genus Pleurosigma has no less than five species, two
being quite new, and both having the markings arranged dia-

16 SuaDBott on New Forms of Diatomacee.

gonally, that is, with (what the Rev. W. Smith considers)
cells placed alternately in contiguous rows. The outline of
the largest (fig. 8) is very clumsy and the ends obtuse, and
the median line but slightly flexed—this | call * validum ;”
the other, P. inflatum, on the contrary, is of a graceful out-
line, the apices acute, the flexure of the median line con-
siderable, and is broad in proportion to its length (fig. 9). A
third species is, I believe, also new; it was observed by
Mr. Capron when making the drawings; but as I have not
had an opportunity of examining it, I have not further no-
ticed it. Specimens of P. formosum and P. Hippocampus are
also found.

There are two new species of Amphitetras, viz. A. ornata
and._A. tessellata ; the former (fig. 10) is of small size, the mar-
gins of the valves being considerably hollowed or emarginate
and folded over so that each valve is not unlike in form to a
collegian’s cap. The surface is elegantly but somewhat irre-
gularly ornamented with delicate markings. A. tessellata (fig.
11) is of larger size, and the markings coarse and resembling
- a tessellated pavement.

There is a very striking and beautiful discoid valve, toler-
ably abundant, of the same genus as one commonly found in
the guano from Callao, but which, I conceive, has never yet
had a generic name. It differs in essential characters both
from the Coscinodiscus and Actinocyclus, and its position
would probably be midway between them.

It is possessed of a pseudo nucleus, is minutely embellished
with delicate markings similar to those seen in Pleurosigma
anyulatum, &c., but in segments radiating from the centre, so
that, in all probability, the front view would exhibit slight
undulations. ‘The absence of any distinct division between
the segments, however, separates it from Actinocyclus. 1
propose for this form the generic name Actinophenia, from
axtiv, aray, and Qaeios, glittering, with the specific designa-
tion splendens.

Fig. 12 is a new species of Hupodiscus, having four pro-
cesses arranged regularly, and with the markings of a some-
what similar character to those in the last described species,
forming an elegant cross; I have, therefore, named it £.
crucifer.

Fig. 13 represents a Campylodiscus latus, also new, the cana-
liculi being wide apart and few in number.

Moderately abundant in this gathering are specimens of a
highly interesting nature, on which the generic name of As-
terolampra has been conferred by Professor Baily, of New
York: one species, A. marilandica, has been figured in ‘the

SHADBOLt on New Forms of Diatomacec. 17

American Journal of Science and Art,’ vol. xlviil.; a copy of
the paper is in the library of this Society, it having been pre-
sented by the late Mr. Edwin Quekett. The Port Natal
species differs in many respects from A. marilandica, as the
following description will show :—

Frustules disciform, slightly convex, cellular (?), elegantly
marked around the margin with 7 or 11 segments of an
elliptical or parabolic outline, radii proceeding from the
centre to the apex of each segmental curve, and strength-
ened with bracket-like projections. The aspect is not unlike
an ornamental wheel, the radii forming the spokes, The seg-
ments are regularly and minutely divided into dots or cells (?),
but it is necessary to use a high power and careful manipula-
tion to display them: when properly shown, however, nothing
can well be more exquisitely beautiful. ‘There is a very no-
ticeable peculiarity in the number of the segments ; in every
specimen I have seen, being either 7 or 11 (a few only of the
latter number), and in the normal state the two valves, as far
as my observation extends, are, without exception, disposed
alternately, that is, that a segment of the superior valve always
corresponds to an interspace of the inferior one, and vice versa.
I have named this species A. impar, from the odd number of
segments. Fig. 141s a representation of this beautiful frustule.

A species of another genus, established by Professor
Baily, Cliimacosphenia, is shown at figs. 15a and 156, b
being the lateral view, and a the front view, in which the
ladder-like divisions more resemble the links of a chain than
in the only other species I have seen: I have consequently
called it Cl. catena.

Two very interesting forms, by no means rare in this very
rich gathering, belong to a genus that has been described.
under the names of Zygoceros and Denticella, the latter by
Professor Baily, and as they clearly differ from the former, as
may be seen by the most casual observer on inspecting fig.
16, which is a single frustule of a true Zygoceros, moderately
common in this collection, I shall adopt the latter designation.
I have only seen them either single or in pairs, having just
completed the process of self-division, having a somewhat
persistent connecting membrane. Front views are shown of
the two new species in figs. 16 and 17. The side view is more
or less elliptical in outline at the junction of the two valves,
but sections in almost every other plane parallel to this would
present a different figure, owing to the protuberances shown
m the front view. In both species there arise from the cen-
tral inflations two slightly curved spines from each valve,
which, as in Triceratium, &c., in the process of self-division,

VOL, II. c

18 SHADBOLT on New Forms of Diatomacee.

are arranged across each other. The smaller of the two spe-
cies (fig. 16), D. s¢mplex, has but one central inflation, and the
lateral expansions are symmetrically placed so as to give each
valve the appearance of a sort of mitre or head-dress. It is
marked with numerous well-defined dots or cells (?). The
second species, D. margaritifera (fig. 17), has, besides the
two lateral expansions, three intermediate inflations, the cen-
tral one being considerably the largest, and the whole is
covered by numerous pearl-like eminences similar in aspect to
those so common in Cosmarium and other Desmidiee. In
both species the union of the two valves is marked by a sort
of projecting band, which completely encircles the frustule.
In addition to those I have described there are very many
other forms already familiar to observers of the Dvratomee,
and doubtless some new forms which I have overlooked. I
am well aware that the present is a most imperfect sketch of
a highly interesting gathering, containing, as will be shown
by the following summary, no less than 55 species, of which
20 are certainly new, and in addition 4 forms of Sponge
spicula.
Species. Species.
Bacteriastrium : . 38 of whichare certainly new 3
Calophyllum
‘Triceratium
Pleurosigma
Amphitetras .
Actinopheenia
Eupodiscus
Asterolampra .
Denticella
Campylodiscus
Climacospheenia _
Navicula
Stauroneis
Pinnularia
Nitzschia,
Grammatophora
Tabellaria
Striatella
Zy goceros
Acnanthes
Cocconeis
Doryphora
Podosphenia .
Synedra
Coscinodiscus .
Tryblionella
Meloseira
Biddulphia
Epithemium .
Dictyochas

Ne)
Be [piu po. eee oan.

And 4 forms of Sponge Spicules.

Ou

St | eS ee tok pH WR Re NOR wr Noe

ana

Lee on Sponge Sand. 19

Observations on the Examination of SPONGE Sand, with Remarks
on Collecting, Mounting, and Viewing FORAMINIFERA as
Microscoric Oxssects. By M. 8. Lece, A.L.A. (Read
June 22, 1853.)

Various papers on the structure of the Foraminifera have
been brought before the Society by Mr. Williamson and others,
but the impression conveyed by those communications has
been that the shells in question are not very easily obtained,
and consequently they are likely to be passed over by micro-
scopists from the want of specimens by which to study
them,

Although the matter of this paper has no pretension to
originality, I am induced to offer these remarks in compliance
with a suggestion thrown out by a Member of our Council,
that if Members would occasionally communicate facts, appa-
rently unimportant in themselves, or new modes of manipu-
lation under the general title of ‘ Microscopic Memoranda,’
such remarks would contribute to diffuse a taste for the pursuit
by facilitating the labours of those whose time and inclination
admit of such researches.

Under this impression I now lay before the Society the
result of my experiments on sponge sand, and the methods
employed to bring the specimens more immediately within
my reach without the labour of picking them out from an in-
discriminate sample of the sand itself.

Having observed that there was some degree of uniformity
in the magnitude of certain species of the Foraminifera, it
occurred to me that by sifting the mass of sand through wires
of different gauges important results would follow, and I
therefore obtained some specimens of wire-gauze of 10, 20,
40, 70, and 100 wires to the inch, and, having also procured
from a sponge merchant about a peck of the rubbish arising
in sorting the sponges, I proceeded to separate the sand into
parcels of different degrees of fineness,

In the first process (employing a gauze with 10 wires to the
inch) I cleared the mass of clippings of sponge, small pebbles,
&c., without obtaining any specimens of shells worth retaining.

In the second (20 wires to the inch) I obtained some very
nice specimens of the Orbiculina adunca and complanata, but
scarcely anything else; these specimens, of which the Mem-
bers may recollect that Dr. Carpenter exhibited a series of
very beautiful drawings at one of our soirées, were thus brought
together, instead of being, as before, scattered through the
mass, at intervals few and far between.

c 2

20 Lee on Sponge Sand.

By means of the third gauge of wire-gauze, specimens of
Peneroplis, and smaller specimens of Orbiculina, were brought
together, with other species of Foraminifera of considerable
variety of beauty and form, the result here obtained being
very decided and characteristic of particular species; for,
although the quantity retained after this process was compara-
tively small in relation to the original mass, yet the specimens
were such as to afford an ample reward for the time and
trouble incurred in obtaining them.

But the most surprising result was obtained by using the
next quality of wire-gauze (that of 70 wires to the inch), the
amount retained being much larger in quantity, and the pro-
portion of shells to sand and other débris being such that
sliders mounted indiscriminately from it yielded several very
good objects in every instance.

From the above samples I was enabled to select, without
difficulty, shells for microscopic observation; in the first two
by the naked eye, and in the latter by using a hand magnifier,
and removing them with the moistened point of a camel’s-hair
pencil.

‘Lhe remaining portion of sand, forming probably 19-20ths
of the original mass, will contain, as may easily be imagined,
a very small comparative quantity of shells; but, nevertheless,
it must not be thrown away. I again passed some of it
through a gauze of 100 wires to the inch: the sample then
retained yielded a fair quantity of shells by washing it in
water, and thus other species characterized by their size were
brought out by adopting the following process: having selected
a dish of sufficient size and depth, and spread at the bottom
of it a quantity of the sand, as much water was poured on it
as would cover the whole to the depth of half an inch; after
allowing the floating particles to settle, the dish was slightly
raised at one end and gently agitated, so as to produce little
eddies in the water. Inashort time it was observed that small
channels were formed in the sand of a whiter aspect than the
other portions ; allowing the water to settle gradually, the dish
was slowly tilted at one end until the surface of the sand was
exposed: the whiter particles being then carefully removed by
means of a camel’s-hair pencil, they were found to consist
almost entirely of very minute shells; and the process being
repeated a few times a large amount (microscopically speak-
ing) was obtained for future examination.

In connexion with this subject I may venture a few remarks
upon collecting, mounting, and viewing specimens of the Fo-
raminifera as far as my experience has enabled me to speak.

When about four years ago I was staying at Weymouth

Lxee on Sponge Sand. 21

with my friend Mr. Woodward, in walking over the Small-
mouth Sand, which is situate on the north side of Portland
Bay, we observed the surface of the sand to be distinctly
marked with white ridges, extending many yards in length,
and parallel with the edge of the water. Upon examining
portions of these we found that they consisted of Foraminifera
in considerable abundance, and, upon scraping up a quantity
of it carefully with a card, we obtained in a short time a
bottleful of material which contained thousands and probably
millions of these minute shells.

My friend Mr. Cocken, during a recent residence at
Brighton, was very successful in obtaining a considerable
quantity of the Foraminifera from the surface of the mud
exposed by the receding tide in Shoreham Harbour; and here
also the surface only should be taken, in order to have a large
proportion of shells.

It is very well known to many of our Members that the
ouze from the oyster beds yields a very fair proportion of
Foraminifera and other materials for microscopic examination,
and I am inclined to think from these evidences that the sur-
face, and the surface alone, of sand or mud banks will yield
satisfactory results. And I should recommend to all those
who contemplate collecting for themselves, or employing others
to do so for them, to take only the surface, being convinced
that a few spoonfuls obtained in this way will yield more
than a spadeful taken indiscriminately. My view of this is
also confirmed by the large amount of shells in the sponge
sand, for being taken from the sea-shores, that which is
gathered up with them is such as occurs only on the surface.
I think it also very probable that a locality sheltered from the
direct action of the sea would be more favourable for finding
these organisms than a bold shore exposed to all the violence
of the wind and waves.

If these conjectures should be borne out by experience, it
is to be hoped that the increased facilities of finding their
habitats will lead to extended obseryations on their living
economy, a subject rendered extremely interesting by the
papers of Mr, Williamson and the writings of Dr. Carpenter
and others, where the subjects of their structure and zoological
position are very ably discussed.

The species of Foraminifera are so numerous that the mere
mention of 575 species described by D’Orbigny as peculiar
to the torrid zone, 350 species to the temperate zone, and 75
species to the frigid zone, sufficiently attests their abundance,
and the samples of sand which have come under my own
observation from the Caramatta Strait in the China Sea, from

22 Luee on Sponge Sand.

Australia, and other localities, afford ample proof of numerous
and beautiful forms.

After collecting these minute shells, two very important
points are, mounting them for future examination, and viewing
them so as to obtain their true structure. Much depends on
the different genera, as to the most eligible mode; the simplest
and most natural is that adopted by Mr. Marshall of placing
them in cells made of perforated card, putting a piece of thin
glass over and sealing it down, so that the objects roll about
loosely, and are viewed as opaque objects by a side light;
another mode, also adopted by the same gentleman, is placing
the shells on a glass slip with a little very dilute gum water,
which causes the shells to adhere sufficiently to the glass as
to admit of the air being exhausted from them when mounted
in Canada balsam. They may then be viewed either as opaque
or transparent objects, but it will be observed that the texture
of the shell which invests the segments of the animal is (as
observed by M. d’Orbigny) very variable, but it almost always
follows the different mode of growth upon which the orders of
that author are founded. When the segments are closely packed
together, the shell is opaque, of a close texture like porcelain,
and without any indications of external porosity ; when the
segments are alternate without a spire, and when the spire is
oblique, the shell is porous, and pierced over the last cells
with a great number of little mouths, through which proceed
the filaments, but which become obliterated when the animal
no longer needs them; when the segments are in a straight
line, when they are coiled upon the same spiral plane, or
when they are alternate, and the shell inequilateral, their
texture is almost as transparent as glass.

From the above description it will be evident that one
single mode of illumination will not suffice for duly developing
‘hel structure of these shells, and I should therefore recommend
that some be mounted loosely in a cell, so that all parts may
be viewed as they roll over; and others ‘be mounted in Canada
balsam, and viewed by means either of the annular condenser
of Mr. Shadbolt or the parabolic reflector of Mr. Wenham.
By these means the difference in structure between the upper
and under surfaces of the same species of shell is brought out,
and that confusion avoided which occurs when direct light is
transmitted.

—~

ees eae et

ee ieee ee ot ee

Rainey on Artificial Light. | 23

A Method of employing Artimciat Lieut for the ILLumina-
TION Of TRANSPARENT Oxsects, by which it is so deprived of
Glare and Colour as to be equal in its Illuminating Power to
the best Daylight. By Gro. Rainey, M.R.C.S., Demon-
strator of Anatomy atSt.Thomas’s Hospital. (Read June
22, 1853.)

Tue principal disadvantages attending the use of gas and
lamp light, as they are ordinarily employed for microscopic
illumination, are the disagreeable and somewhat painful glare
and the unnatural colour which is given to all objects thus
illuminated.

These inconveniences are not felt so much where only a
plane or concave mirror is used, as when the light is concen-
trated upon the object by an achromatic condenser ; and, in
the former case, they are partially remedied by transmitting
the light through a piece of ground glass, either common or
coloured ; or by dulling the surface of the mirror; but in the
latter one, these means, by cutting off too much light, are
productive of more harm than benefit, especially where the
markings upon an object are very delicate and require a parti-
cular kind of illumination to render them distinctly visible,
as, for instance, the dots on the Pleurosigma angulatum.
Hence, unless some other plan be adopted for moderating the
intensity of all artificial light and correcting its colour, the
employment of the achromatic condenser must either be
limited to the hours of a good daylight, or the observer be in
danger of materially injuring his eyesight.

Mr. Gillett’s apparatus for producing the effect of a white
cloud does, 1 am informed, remedy all the defects of lamp-
light, but, from some difficulty or other in constructing or in
applying it, its employment has not become general.

The plan to which I have to call your attention is especially
applicable to Mr. Gillett’s condenser, and may at a compa~
ratively small expense be made a part of that most useful
instrument.

Before proceeding further I may observe that the principle
upon which my apparatus is constructed is one which has
been of general adoption for the preservation of the eyes of
those who use glasses, and therefore so far has no claim to
originality ; but its precise construction and application to the
microscope, and its effect in rendering artificial light equal if
not superior to the very best daylight, are admitted by those
who have seen it, and, to the best of my knowledge, are also
new. But my motive has not been novelty but utility, in
bringing this subject under the notice of this Society.

24 Rainey on Artificial Light.

Now that which gives the peculiar burnish or glow to all
objects when highly illuminated, whether by the direct rays of
the sun, or by light proceeding from ignited matter, is due to
the heating portion of the spectrum and certain coloured rays.
In the former case we make use of light for microscopic illu-
mination which has been deprived of this burnish by its
having passed through the clouds; and in the latter this can
be equally well effected by passing the light emanating from
gas or a lamp through such transparent coloured media as
will stop the calorific rays, and at the same time furnish the
kind and amount of colour necessary to form, with the coloured
rays of the flame, white light.

The combination which I find to answer best is the fol-
lowing :—

One piece of dark blue glass, free from any tint of red, one
of a very pale blue with a slight shade of green, and two of
thick white plate glass, all cemented together with Canada
balsam,

This combination so completely stops the calorific rays, that
when the direct rays of the sun are concentrated by a bull’s
eye of the ordinary size upon a lucifer-match with this medium
intervening, it does not become ignited ; and when this medium
is used with Gillett’s condenser, objects illuminated by the
light of a camphine lamp appear as if they were seen by a

bright daylight.

Boswe tt on Actinophrys Sol. 25

- Remarks on Acttnorurys Sot. By R.S. Boswett, Spring
Hill Cottage, Charmouth, Dorset. (Read Oct. 26, 1853.)

In an interesting paper in the ‘ Journal,’ of a description
of Actinophrys Sol, by A. Kolliker, &c., (Vol. L., pp. 25
and 98,) the author, after entering into a very minute descrip-
tion of this curious animalcule, says:—‘‘ The creature also
seems to be capable of altering its entire form to a certain
extent, and to be able to expand and again contract itself in
toto. More extensive and more energetic movements do not
occur at all, and I am consequently altogether ignorant as to
how locomotion of the animal is effected.” My object in
sending this short notice is to give him that information which
he seems to want, though perhaps by this time he may have
made the same discovery as myself, if not, it cannot but be
interesting, not only to him, but also to others, who take an
interest in these minute wonders of creation.

The “ Sun animalcule” is very common in this part of
Dorsetshire ; it abounds in pools where Desmidiee are found:
they are ravenous feeders, not only upon the Desmidiee, but
also upon all kinds of minute spores and animalcules. It was
on examining some beautiful Desmidiee, a few evenings
back, that my attention was arrested by the curious appearance
of two or three very small Actinophrys floating very lightly
upon the surface of the water in the form of a ball, with their
delicate tentacular filaments perfectly erect all over their
bodies ; in fact, they seemed to be floating upon these delicate
filaments. This beautiful and curious appearance, so different
from what I had generally observed, induced me to request
Mrs. Boswell to look at it, but, while she was rising from her
seat, I exclaimed, ‘ You are too late, the little creature has
given a leap, and I have lost it!’ but upon moving the slide
in the direction of the leap, I found the creature composedly
resting in the usual manner upon the surface of the water—
that is, in a flat position. This was not a solitary instance, for
about five minutes after another gave a similar leap: the dis-
tance must have been very great considering the size of the
animal, as it was in the centre of the disc under Messrs.
Smith and Beck’s 2-3rd object-glass with the second eye-piece,
and I had to travel full an inch beyond the radius. These are
the only two instances I have met with at present, not having
made the little creature my peculiar study.

I have frequently mounted the Actinophrys Sol with Des-
midiee, but they generally burst at the edge of the sphere
owing to the pressure of the glass cover, although they are to

VOL, Il.

26 Busk on Avicularia.

all appearance considerably thinner than Micrastorias denti-
culata.

Remarks on the Structure and Function of the AvICULARIAN
and Vipracutar Oreans of the Potyzoa; and on their
value as diagnostic characters in the classification of those

creatures. (Read Nov. 23, 1853.)

Tue Polyzoa, or, more properly speaking, one class of the
Polyzoa characterized by the possession of a movable semi-cres-
centic lip, furnished with a corneous rim, at the mouth of the
cell,—the cheilostomata as | have elsewhere termed them, or
Celleporina of Ehrenberg,—are, many of them, distinguished
by the presence of appendicular organs affixed to one part or
another of the cells of which the polyzoarium is composed.
These organs are of two kinds, the one a sort of pincers, and
the other consisting of a long, slender, movable seta. To the
former set of organs, of whatever form, the term avicularium is
here applied, and the latter are designated as vibracula.
With respect to the structure of these organs of either class it
is sufficient to remark that, however diverse their appearance
may be, they are all constructed upon the same general type,
that is to say, the organ consists of a hollow cup or receptacle
containing two sets of muscles for the movements of its motile
portion, the mandible, as I term it in the one case, and the
seta in the other. Beyond this general conformity in type,
however, my knowledge of the more intimate structure and
contents of the cup in the vibracular organs, does not allow me
to approximate them to the avicularia.

The avicularia, besides the movable mandible, it may be
observed, always have a corresponding fixed beak, the opponent
as it were of the mandible, and necessary to constitute the
organ, what I presume it to be, an instrument of prehension.
This beak is needless, and is therefore wanting in the vibra-
cula, and its absence in cases where the movable part is
detached, would serve to distinguish one kind of organ from
the other.

I. The avicularia.—

The first notice we have of the existence of these organs
or rather of one form of them, is contained in Ellis’s account
of what he terms the “ Bird’s-head coralline,” (Nat. Hist.,
Zooph., p. 36, pl. 20,) where he says, ‘On the outside of each
cell we discover, by the microscope, the appearance of a bird’s
head, with a crooked beak opening very wide.”

Busk on Avicularia. ) 27

Mr. Darwin, in the ‘ Voyage of the ‘Adventure’ and
‘ Beagle,’ adverts at some length to these organs, and de-
scribes their actions in the living state very graphically. They
have also been described with great care by Dr. Van Beneden
and the late Professor John Reid, and also by Nordmann
and Krohn, the latter (as I extract from Dr. Johnston’s ‘ Hist.
Brit. Zooph.’) classifying them under three different forms:
1, those which have the figure of the crab’s arms; 2, those
which resemble pincers; and 3, those which are formed like
bristles or hairs; the last corresponding to what are here
termed the vwibracula.

In a paper read before this Society, October 27, 1847, and
published in the ‘ Transactions,’ I have described more particu-
larly the structure of the curious and unique form presented
by this organ in Notamia bursaria, pointing out, I believe for
the first time, that the muscles were divisible into two distinct
sets, one for the closure and the other for the opening of
the mandible, with other minute particulars of their mecha-
nical arrangement previously unnoticed; I also stated that the
muscles not only in this organ but throughout, in this and
other Polyzoa, are of the striped kind, or resembled those of
the Brachiopoda more than of any other class in the Mollusca.
I also indicated that the mandible and the beak of the cup
were differently constituted to the rest of the organ, being com-
posed of a horny instead of calcareous substance ; and that
besides the two sets of muscles above noticed, the cup con-
tained a “ peculiar body of unknown nature.”

I believe that up to the present time our knowledge of these
organs is pretty nearly limited to the above particulars. With
respect to their homologies and functions, nothing but con-
jectures have been offered; in fact, as regards the homo-
logies of these organs with any existing in animals belonging
to the same or any other class, no conjectures beyond the most
vague have been offered. They may, perhaps, be regarded as
analogous in function with the Pedicellarie of the Echino-
derms, as well as with the little accessory cups filled with
prehensile filaments, or thread cells, which are found in the
Plumulariz and Campanulariade ; but, I conceive that any
homology with these organs is quite out of the question.
They are as nearly related to the claws of a lobster or the feet
of a Pygnogonum.*

* Mr. Huxley has pointed out to me several points of resemblance be-
tween the avicularia, especially as to their mechanical and muscular ar-
rangements, and the shells of the. Brachiopoda. An ingenious idea, and
calculated to lead to the more serious consideration of the relationship
between the Polyzoa and Brachiopoda, as suggested by Mr. Hancock

d 2

28 Busk on Avicularia.

Their structure so obviously indicates their aptitude for pre-
hension, that the supposition of such being their function has
been long entertained: and I have myself : no doubt whatever
as to its being so; for, as Dr. Johnston observes, ‘ although
they are too short to hand the prey to the mouth, yet, retained
in a certain position, and enfeebled or killed by the grasp, the
currents set in motion by the ciliated tentacula may then
carry it within reach.” (‘ Brit. Zooph.’ p. 334.) Some time
in the last year, a specimen of Scrupocellaria scruposa, if
I remember right, was exhibited at one of our meetings, with
a minute vermicule, retained in the grasp of its avicularia ; and
the same thing seems to have been repeatedly noticed. An
instance of the kind occurred to me when at the sea-side this
autumn, and [ have made a figure to represent the occurrence
(Plate IT. fig. 12). It 1s ofa portion of Scrupocellaria seruposa,
two of the avicularia on which have, apparently simulta-
neously, caught a minute vermicule which they retained with
a most tenacious grasp. I kept the zoophyte under observa-
tion for several days, in the living state, and during that time,
in fact, till the whole died, the grasp of these organs was not
relaxed ; and, although the movements of the captive were
very active and apparently energetic, it was unable to liberate
itself from the grim hold of its tiny but persevering antagonist.
Another instance of the grasping propensity of these organs
is exhibited in fig. 10, where two of them appear to be
engaged in deadly combat. This figure is also intended
to show the disposition of the muscles when thus employed.

Considering, therefore, the conformation of the avicularia,
and the instances in which objects of prey of different kinds
have been noticed engaged by them, I think it is impossible
to avoid the conclusion that they are for the prehension of ob-
jects, either for the purpose of using them for food when dead
and powerless, as suggested by Dr. Johnston; or it may be for
purposes of defence.

With respect to the structure of the avicularium, I aie
already stated what is known; and have, in addition, only
to remark that it hag occurred to me to notice a cirewmatamne
hitherto overlooked, and which may eventually serve to throw
some light upon the “ peculiar body” contained in the cell to
which I adverted in my observations on Notamia. — It was in

(‘ Ann. Nat. Hist.,’ 2nd Ser., vol. v. p. 198), than has hitherto been given
to it. And with regard to this, it should be borne in mind, though per-
haps the character is of no great importance, that all the Brachiopoda
have striped muscular fibres, whilst for the most part the other classes of
Mollusca, with some exceptions—Pecten, for instance—all te muscles of
the unstriped kind,

Busk on Avicularia. 29

that species, also, that I first noticed (in 1852) the fact that
when the mandible is thrown back, or, in other words, when
the avicularium is open, a slight prominence comes into view,
covered with delicate setose hairs, which do not seem to be of -
the nature of cilia, because they exhibit no motion. These
minute sete appear to be seated’on the “ peculiar body ” above
adverted to, and which again seems to be so connected with
the muscles by which the mandible is closed, or rather,
perhaps, to a membrane by which they are covered, or by
which the opening of the cell is closed, when the mandible is
thrown back, as to be protruded, simply by the throwing back
of that process; so that the sete are then made to project
beyond the level of the cup, and are withdrawn as the man-
dible closes. Fig. 2 represents this apparatus in Wotamia.
Fig. 7, the same thing in Bugula plumosa, and fig. 9, in
Bugula avicularia. ‘These are the only three species in
which, up to the present time, | have been able to perceive
this arrangement; but not having had an opportunity of ex-
amining the avicularia of any other, except Scrupocellaria
seruposa, for the purpose, and in which I was unable to detect
it (fig. 13), I am not prepared to say that it obtains univer-
sally. It is probable, however, that in a modified form it may
do so. I am inclined to the opinion that itis atactile organ,
the object of which is to apprize the occlusor muscles of the
contact of any minute floating object, upon which the muscles
immediately contract, and either close the avicularium against
the invasion of a foe or capture the appropriate prey.

A second point that I have also observed in these organs,
and which, I believe, has not been before noticed, is that the
portion of the cup in which the muscles and the greater part
of the peculiar organ (which might probably be regarded as a
nervous ganglion) are placed, is closed in by a delicate mem-
branous tympanum, which has a central perforation, through
which the conjoined tendon of the occlusor muscles passes, and
also a second smaller opening (at all events in B. avicularia),
the object of which I do not know. This tympanic mem-
brane is shown in fig. 8.

So much for the structure and conjectural function of the
avicularia ; and to proceed to consider the vibracula in the
same particulars.

1. As to the structure of these organs, I have nothing new
to offer. ‘They consist, as I have said, of a cup containing the
muscular apparatus, and of a movable seta, articulated to the
cup, and which appears to be moved in the same way as the
mandible of the avicularia. This seta is in most cases simple
and terete ; in others, as, for instance, generally in the genus

30 Busx on Avicularia.

Caberea, it is toothed on one side; and in others, as in the
species forming the family Selenariade, of which we have no
British representative, the seta is very variously and curiously
formed, in some being trifid or bifid at the extremity, and in
one, Selenaria maculata, it is spirally contorted and minutely
annulated, so as very closely to resemble the proboscis of a
butterfly.

As to the function of the vibracula, it would appear, in most
cases, to be simply defensive. ‘The seta may be observed in
almost constant motion, sweeping slowly and carefully over
the surface of the polyzoary, and removing what might be
noxious to the delicate inhabitants of the cells when their
_tentacula are protruded.

Another circumstance often to be observed with respect to
these organs, is this, that each presents inferiorly a rounded
perforation, as in Scrupocellaria and Canda, sometimes chan-
nelled as in Caberea, which indicates the point of attachment
of a radical tube or fibre. That this connexion with a radical
tube, however, is not an essential attribute of the vibracular
organ is sufficiently obvious from the circumstance that those
tubes are frequent where no such organs exist; but where
there are vibracula, the tubes invariably enter them, and not
the cell itself. This is especially evident in the genus Canda,
of which the British species, Canda (Cellularia) reptans, affords
an instance.

In the case of the Selenariade or Lunulites, 1 think it not
improbable that the vibracula may be subservient to loco-
motion.

These organs, both avicularian and vibracular, appear to me
to be of very considerable importance in a systematic point of
view ; and, although from our imperfect knowledge of them,
and in fact of the Polyzoa in general, the supposition can only
be regarded as problematical, it seems not improbable that
the presence or absence, especially of the avicularium, may be
connected more directly with the intrinsic nature of the
species upon which they are found, than has hitherto been
supposed. It may, for instance, be the case, that those furnished
with these offensive weapons live upon a kind of food different
from that of the others who do not require such an aid in the
capture or weakening of their prey. The Polyzoamay, per-
haps, thus be divided into vegetable and animal feeders, or into
feeders upon dead, and those which feed upon living organisms.
One thing, however, is certain, that these organs afford, in many
cases, excellent and available systematic characters ; and this
part of the subject I will now proceed briefly to discuss.

I have already stated that the accessory organs we are now

Busk on Avicularia. 31

considering are divided into two kinds, apparently with dis-
tinct functions—avicularia and vibracula; the one, probably
prehensile, the other defensive. Of these, the avicularia are
found by far the most extensively ; in fact, they are wanting
in but few of the genera constituting the cheilostomatous
class of Polyzoa. In employing them for the purpose of
classification, it is necessary to subdivide them into three
classes. 1, the pedunculate. 2, the sessile; and 3, the
immersed, The two latter classes, however, run insensibly
into each other, whilst the pedunculate form is obviously
quite distinct, inasmuch as it presents an additional member,
in the form of a basal joint. It is this form of avicularium to
which the term “ birds,” or “ vultures’ heads,” is more pro-
perly applied. It is well known in this form, as it occurs in
Bugula avicularia, B. plumosa, and B. flabellata: it is also
found in Bugula tridentata (Krauss), a South African species ;
and in Bicellaria ciliata; whilst it is wanting altogether in
Bugula neritina, Bicellaria grandis, and Bicellaria gracilis.
A second modification of pedunculate avicularium, where it
assumes the form of a long trumpet-shaped or infundi-
buliform tube, exists in Bicellaria tuba. So far as I know
then, at present, the pedunculate form of avicularium is
restricted to the genera Bugula and Bicellaria, though it does
not exist in every species of either genus, and in one, assumes
a form quite different from the ordinary. All that can be
said about it, therefore, in those two genera, is that where the
avicularia exist, they are of the pedunculate variety. The
true ‘“ bird’s-head” avicularia are always placed on the an-
terior aspect of the cell, on one side below the level of the aper-
ture, whilst the tubiform variety arises on the back of the cell.

The sessile form of avicularium, as I have observed, may
be subdivided into the projecting and the immersed. Of
these, the latter is much the more extensively distributed : it
is placed either at the angles or margin of the cells, or on
some other part, usually of their anterior aspect, but some-
times on the posterior: instances of the latter are presented
in Caberea nuda, where the vibracular organs, so characteristic
of the other species in the same genus, are replaced by what
may be termed avicularia, though, in fact, they should more
properly be referred to the vibracular type, inasmuch as
the radical tubes enter their bases. The genus Retepora, also
offers an instance of the posterior position of true avicularia ;
but, with these exceptions, I am not acquainted with any
other in which the avicularia are not on the sides or front of
the body, as indeed, if our surmises with respect to their func-
tion be well founded, might be expected.

32 Busx on Avicularia.

Of angular imbedded avicularia, the numerous species
of the genus Catenicella afford examples. ‘This organ, in
fact, in that genus, often furnishing very satisfactory specific
characters. In some, as C. plagiostoma, it is of gigantic size,
in others very minute, and in one it seems to be aborted, being
replaced by channelled processes, C. carinata. In several
other species it is in some cells replaced by long ascending
cornua or hollow spines, as in C. cornuta and C. taurina.

The genera Menipea, Canda, Scrupocellaria, and Cellularia,
are respectively distinguished by the presence or absence of
avicularian and vibracular processes. The former are always
of the sessile kind, either zmmersed, and at the superior and
outer angle of the cell, or projecting and placed on the front
of the cell, below the level of the aperture. In the genus
Menipea, there is an angular, superior, imbedded ayicularium
in many of the cells, and a projecting sessile organ on
the front of the cell below the aperture, and no vibracula.

The British species, Menipea ternata, affords an instance ;
the other species similarly characterized, are—WM. cirrata,
M. fuegensis, M. triseriata, M. ornata, M. patagonica, and
M. multiseriata. The genus Canda, differs from Scerupocel-
laria, mainly in the want of any avicularian process at
the superior and outer angle; but the cells sometimes have a
sessile avicularium in front, below the aperture. ‘This is
particularly the case with Canda arachnoidea, in which the
avicularia appear to occupy an unusual position: they do not
seem to be seated on the fronts of the cells themselves, but to
form a series affixed to the median septum between the two
rows of cells ; and, what is very curious with regard to them
in this species, they are apparently developed long after the
completion of the cells, seeing that they are totally wanting
in the upper and younger portions of the branches of
the polyzoary, and gradually increase in size towards the
inferior portion. In Scrupocellaria, we arrive at, the full
development of these accessory organs; the species in this
genus being all distinguished by their being furnished with
both avicularia and vibracula. Of the former, one is always
imbedded in the superior and outer angle, as in Scrupocellaria
scrupea, S. scruposa, and S. Macandret ; whilst in others, such
as S. ferox, and S. cervicornis, there are superadded to these,
sessile avicularia on the front of the cell below the aperture,
in the former species, of colossal dimensions. The genus
Cellularia, again, is distinguished by the entire absence
of both avicularia and vibracula. The British form Cellularia
Peachit, affords an instance.

The genus Caberea, except in the single species Hewett re-

Busk on Avicularia 33

ferred to, and which might, perhaps, on that account, almost be
regarded as the type of a separate genus, is distinguished, and
very remarkably so, by the extraordinary size and curious
arrangement of the vibracula on the back of the branches,
which thence derive a very close resemblance to an ear of barley.
It is in this genus that the vibracular organ acquires its ex-
treme development. A British example is afforded in Caberea
Boryi, a not uncommon denizen of the Channel coasts. In
the genus Hmma, we have afforded an instance, in which the
position of the organ may be used in the generic character.
In the species belonging to this genus, the sessile, lateral
avicularium is situated on a level below the aperture. £. ¢.,
Emma crystallina and E. tricellata. |

The peculiar disposition and form of the avicularia, in
Notamia, have been sufficiently adverted to in this and my
previous communication to the Society.

It would require too much of your time and too much
space to enter very particularly into all the instances in which
I have found the form, position, and existence of avicularia
and vibracular processes useful in the classification of species.
The above remarks, hasty as they are, will serve to give
an idea of the extent to which they may be so employed ;
and I would only observe, in addition, that a similar atten-
tion to these organs will be found indispensably requisite for
the due appreciation of specific and even generic distinctions,
in the difficult and hitherto much confused families of the
Flustrade, Membraniporide, and especially of the Celleporide,
Escharade, and Selenariade. In Lepralia, particularly, in
which genus I have placed nearly 60 species, I have found the
use of these organs of the utmost importance, and easily avail-
able. In fact without them it would have been a most difficult
task to marshal into due order such an irregular and mutinous
host. For the mode in which I have so employed this
character, | must refer you to my ‘ Catalogue of Marine
Polyzoa,’ just published by the British Museum, and will
conclude by saying, that the names of the Polyzoa here em-
ployed are those by which they are distinguished in that
work, in which the appropriate synonyms will be found.

d4 Structure of a peculiar Combustible Mineral,

On the Minute SrructureE of a peculiar CompustiBte MineE-
RAL, from the Coal Measures of TorRBANE-HILL, near Batu-
GATE, LintirHGowsHIRE, known in Commerce as BoGHEAD
CannEL Coat. By Joun Quexerr, Professor of Histology
to the Royal College of Surgeons of England. (Read
Nov. 23 and Dec. 21, 1853.)

Tue substance in question has lately excited the greatest
interest in the scientific world ; and_a trial, second to few in
importance, has recently taken place in Edinburgh, having
for its object the determination whether the Torbane-hill
mineral should be called a coal or not, and whether it should
be included in the missive of agreement for a lease, and let as
coal. Those of my hearers who may wish for a particular
account of the matter in dispute, and a statement of the facts
brought forward, both by the pursuer and defender, or, with us
in England, plaintiff and defendant, I would beg to refer to
Mr. A. W. Lyell’s Report of the trial, published by Messrs.
Bell and Bradfute of Edinburgh. °

Upon this trial no less than seventy-eight witnesses were
examined—thirty-three for the plaintiff, and forty-five for the
defendant. They might be classified as geologists, mineralo-
gists, chemists, microscopists, and practical engineers, such as
gas managers, miners, &c.

With four of these classes of scientific witnesses I have no
immediate concern, and will, therefore, leave them to settle
their own differences ; but not so with the microscopists, with
many of whom my opinions are entirely at variance.

In order that you may all fairly understand the nature of this
question, as far as the microscopical observers are concerned,
I will, in the first place, give you a detailed account of the
minute structure of the Mineral itself. Secondly, I will give a
brief description of the minute structure of Coal. Thirdly, I
will lay before you the whole of the evidence given by the
microscopists on the part of the pursuer as well as the defender;
and lastly, make a few remarks upon the conflicting testimony
of some of the witnesses.

I wish that the matter had fallen into abler hands than
mine; but having been intimately acquainted with the
mineral in dispute for some time past, and as two of the oldest
members of this society, Mr. Bowerbank and myself, have
had their competency called in question, and have been repre-
sented by the Judge as no botanists, and, therefore, “are not,
as [ understand, conversant or skilful in fossil plants,” and the
society itself not having escaped his ridicule, the jury being

from the Coal Measures of Torbane-hill. 39

informed that the Microscopical Society of London is “a
learned body, who make it their object to pry into all things,”
I cannot be silent; but I would have you keep in mind that
my sole motive in now appearing before you, is, the cause
of truth, and in this cause I come forward fearlessly, but
honestly, to state that the Torbane-hill mineral is not, micro-
scopically speaking, a Coal ; that it is not like any of the combus-
tible substances used in this country as Coal ; and that, althouyh
possessing some of the properties of Coal, it is, notwithstanding,
a mineral sui generis, having avbasis of clay which is strongly
impregnated with a peculiar combustible principle, and that when
plants are found in it, they are accidental, and have no more been
concerned in the formation of the mineral than has a fossil bone
in that of the rock in which it may be imbedded.

1. External characters of the Mineral.—Of these you will
have a good general idea from the specimens on the table before
you. It frequently occurs in seams of some considerable
thickness, and always in the neighbourhood of coal, some-
times in immediate contiguity with it, but at other times,
according to Mr. Ansted, separated from it by a layer of fire-
clay. The colour is generally a dark brown or black, without
lustre, but varies according to its position in the seam;
its specific gravity is 1%, or 1,%, water being as 1. When
scratched with a knife it exhibits a brown streak, in which
particular it is said to differ from all the known coals with one
or two exceptions. It is tough and not so brittle, but that
very thin sections may be made of it, and when struck with a
hammer, it emits a dull sound; the remains of plants, espe-
cially Stigmaria, are of constant occurrence, and can be dis-
tinguished by the naked eye without difficulty.

2. Characters exhibited under the Microscope.-—When a
small chipping or fragment, about half an inch square, is
examined as an opaque object under a power of 40 or 50
diameters, it will be found to consist of masses of a yellow
material, some being of irregular figure, others more or less
rounded, imbedded in a granular matrix, varying in colour
from a yellowish-brown, almost to black. The whole of the
mineral appears to be composed of granules of various sizes,
and although the part which has been termed the matrix is
black, this also will become brown if the surface be scraped.
The scraping can readily be done under the microscope whilst
the fragment is being inspected ; and, curiously enough, both
the surface of the mineral, and the minute particles scraped
off, assume a light-brown colour. Portions of plants imbedded
in the mineral can, by the process of scraping, be readily
distinguished from the impressions of plants ; the former are

36 Structure of a peculiar Combustible Mineral,

always black and do not alter in colour, whereas the latter
become brown, the same as other parts of the mineral.

3. Characters exhibited by sections under the Microscope—
‘There appear to be two principal varieties of this mineral,
one of a yellowish-brown colour, the other nearly black, these
differences, however, are chiefly dependent upon the position
the particular fragment selected for section occupied in the
block. When the first variety is reduced sufficiently thin to
be transparent, which can be done without much difficulty, it
will be seen to consist of a tolerably uniform, yellow mass,
whilst the darker variety is either of a rich brown, or of a
pale-yellow colour, minutely spotted with black granules.
When the first or yellow variety is examined with a power of
50 or 100 diameters, it exhibits an appearanee of being made
up of a mass of transparent rounded particles or spherules of
a rich yellow or amber colour, varying in size from the zyg,th

to the s}5th of an inch (as shown in Plate III, fig. 1), whilst

the darker variety (fig. 2) is composed of two essential ele-
ments, one in the form of the transparent rounded particles,
the other minutely granular, but black and opaque, and
occupying the spaces between the yellow particles. In the
first variety of this mineral, or that which is of a yellowish-
brown colour in section, the yellow particles above alluded
to are so very abundant, that they appear almost to make up
the entire mass, whilst the dark granular element is small in
quantity. In the second, or dark variety, the strictly granular
opaque element is much more abundant; it sometimes occurs
in large patches, having none of the yellow particles with it,
but more frequently it is found in the form of a coating to
the particles themselves. When the yellow particles are of
large size, they always exhibit more or less of a radiated
structure internally: this appearance, which is well represented
in figs. 1 and 2, very much resembles that of a radiated frac-
ture, or a species of crystallization. I shall now, for the sake -
of distinction, call all these yellow particles, or spherules, the
bitumenoid or combustible portion of the substance, and the
dark, granular part, I shall consider as the strictly mineral, or
earthy ingredient.

In some specimens there is a tolerable regularity in the size
of the yellow particles, and in the disposition of the black
mineral ingredient around them, so much so that an unprac-
tised eye might, at first sight, consider its structure to be cel-
lular: that such mistakes have actually been made you will
very soon have an opportunity of learning.

Having told you what is the usual structure of the substance
in question, [ must beg you to understand that it matters little

from the Coal Measures of Torbane-hill. — 37

in what direction the sections are taken; whether cut verti-
cally, horizontally, or obliquely, there is no perceptible
difference in the structure, and I say it without fear of con-
tradiction, that no one, however skilled in microscopical
observation could, from the imspection of a single specimen,
state the direction in which the section had been made. Such
is not the case with coal, as will hereafter be shown; a single
inspection is sufficient to enable a practised microscopist to
determine the actual direction of the section, whether trans-
verse or longitudinal.

Examination of portions of the Mineral having Plants
imbedded in their substance—I have already stated that
plants and the impressions of plants are not uncommon in this
mineral ; of these | have made numerous sections and chip-
pings, and most instructive they all are. The plants appear to
be principally Stigmarie, and exhibit more or less of the three
tissues known to botanists as the cellular, the woody, and the
vascular ; and should one or more of these be present in any
section, the minutest fragment even of a cell or vessel can be
readily recognised by a practised observer; they, as it were,
stand out boldly from the mineral matter in which they are
imbedded, and (as shown in figs. 3 and 4) can be distinguished
in all cases by their rich brown colour; but such plants I not
only consider as extraneous and not forming the bulk of the
mineral, but such plants my investigations lead me to conclude
rarely if ever form coal; at all events no coal that [have yet
examined has ever exhibited the least trace of being made up
of such plants as are so commonly seen imbedded in this
mineral. Even the coal lying upon this mineral, and running
through it in every possible direction, is composed principally
of woody tissue, and not of plants such as these.

Examination of sections of the Mineral having Coal in juxta-
position.—The first specimen of this kind which I had the
opportunity of examining was brought by Mr. Bowerbank
himself from one of the Torbane-hill pits. From this speci-
men several sections were taken; one of them slightly mag-
nified, is represented in Plate V., fig. 1. I regret I cannot
show you the specimen itself, it being lodged in the Court of
Session, in Edinburgh ; but [ have been favoured with a some-
what similar one through the kindness of Mr. Gratton. As the
block lay in the pit, the coal was situated below the mineral
in the position I now hold it, and you will readily be able to
distinguish the one from the other by the naked eye; but
when viewed with a power of at least 50 diameters (as
shown in Plate III., fig. 5), the smallest fragment of the coal
that may happen to be mixed up with the mineral may be

38 Structure of a peculiar Combustible Mineral,

readily traced ; even a part so minute as a single woody fibre
can easily be recognised.

In some specimens, the line of demarcation between the
coal and the mineral is not very decided, owing to the coal
and the plants found in connexion with it being so intimately
blended ; in all such cases recourse should be had to the
streak, as the best guide to distinguish them. In every part
of the block containing coal and coal plants, the streak is
black ; but in the smallest portions of the mineral it is brown.
It is a curious fact, however, that in the specimen now before
you, three kinds of structure are visible to the naked eye:
Ist, true coal; 2nd, a mixture of coal with a few coal plants,
principally Stigmarie ; 3rd, the mineral. When sections are
made through the block in two directions at right angles to
each other, the coal and the mixture of coal and plants will
exhibit a structure corresponding with longitudinal and trans-
verse sections of wood, but the mineral is the same in both
sections. The yellow particles occupy all the interstices in the
coal, and vary in shape, according to the spaces they have to
fill (as shown in fig. 5); but whether they be elongated or of
circular figure, more or less of the radiated structure is present
in every particle. In such sections the vegetable tissues may
be distinguished from the earthy ingredient by their rich
brown colour.

Examination of the Powder.—W hen the Torbane-hill mineral
is reduced to powder, and examined either in water or in
Canada balsam, the combustible and incombustible portions
can be well seen; the one occurring in the form of the yellow
or amber coloured particles before noticed, and constituting
full two-thirds of the mass (as shown in Plate IIL, fig. 6),
whilst the remainder is made up of minute opaque granules,
having occasionally amongst them some which are quite
transparent, and probably siliceous.

Characters of the so-called Coke and of the Ash.—Three por-
tions of the coke of the Torbane-hill mineral, each about
4 inches square, obtained from a gas-retort by Mr. Gratton,
were of a greyish colour, and when scraped became perfectly
black. The remains of plants were very visible throughout
the substance of each, and were even more distinctly seen in
the specimens of coke than in the mineral itself before being
subjected to heat, for every part, however minute, had
assumed a silvery appearance. When a flat piece of the coke,
about half an inch square, is examined as an opaque object
under a power of 50 or 100 diameters, it presents a peculiar
sponge-like structure ; and when contrasted with a portion of
the mineral, it will be noticed that all the yellow particles

from the Coal Measures of Torbane-hill. 39

have disappeared, and a pitted appearance is produced, the
pits being nothing more than the cavities in which the yellow
particles were lodged, and the walls of the pits being the
granular earthy ingredient which at one time surrounded the
yellow particles. When small fragments of the coke are
scraped off and subjected to a power of 250 diameters, none
of the yellow combustible principle is present, the entire
bulk being made up of dark granular masses. If the mineral
be burnt in anopen fire, the ash will be nearly white; and
when examined microscopically, no trace of the yellow com-
bustible matter will be seen, and the granules (as shown in
fig. 7) will be very minute, and of a light colour. These
appearances will be constant, if care be taken to select a part
of the mineral in which no traces of plants are visible to the
naked eye; but if portions of plants be present, they will be
readily recognised by their woody and vascular tissues. The
principal distinction, therefore, between the coke of the gas-
works and the ash is, that in the former the granules are
larger and blacker than they are in the latter.

From these and numerous other observations, I con-
clude that the mineral in question is a clayey substance, im-
pregnated with a combustible material occurring in the form
of rounded particles of a rich yellow or amber colour, but
whether these particles be bituminous or not the chemists
must decide.

What I have already stated refers exclusively to the
Torbane-hill mineral, and no mention has yet been made of
the structure of coal. Under this head I could enter into a
detailed account of most of the well-known varieties of British
coal, my knowledge of which has been principally derived
from a careful investigation of sections made by myself and
by my friend Dr. James Adams, of Glasgow; and I am
happy in having this opportunity of bearing testimony to
the correctness of the observations of Dr. Adams, upon which
his opinions had been formed prior to my having the pleasure
of his acquaintance. Were I now to describe these, I fear
you would be kept here many hours; but it is the intention
of Dr. Adams and myself, at no very distant period, to read a
paper on the minute structure of the principal kinds of British
coal, before the Geological Society, as we deem that the most
fitting place for such a subject. For our present purpose,
therefore, it will be merely necessary for me to give, in as con-
cise a manner as possible, the results of the investigations of
Dr. Adams and myself on this point ; but I would have you
understand that although I give youa general description of the
structure of coal, | have with me the specimens from which
you will be enabled to judge for yourselves whether my state-

40 Structure of a peculiar Combustible Mineral,

ments be correct. I am fully aware that the prevalent opinion
with geologists and botanists is, that coal is made up of fossilized
vegetable matter, and that this vegetable matter may consist of
stigmariz, ferns, mosses, &c.; in short, of a great variety of
vegetable substances. My investigations, however, lead me
to believe that the basis of coal is essentially a peculiar kind
of wood, and that when ferns, stigmariz, lepidodendra, and
other plants occur in coal or its neighbourhood, they should
be considered foreign to the coal, as these plants, before
noticed, are to the Torbane-hill mineral. However contrary
this may be to our preconceived notions, yet all the sections
on the table before you, on a careful examination by an unpre-
judiced observer, can lead to no other conclusion. I believe
that there are in this room at the present time more sections
of coal than any private individual has ever yet produced
before a scientific assembly, and it is from these specimens,
and from the study of these alone, that I am warranted in
making this assertion. ‘The botanist will remember that most
of the plants generally considered as forming coal, are such
as on section will exhibit more or less of the cellular, woody,
and vascular tissue: now it is a remarkable fact, that most
of the plants visible to the naked eye in the ‘Torbane-hill
mineral, as well as those lying in the strata above and below
coal in general, are those which may contain spiral or other
vessels; but, judging from all the sections of coal now before
you, as well as chippings of others too numerous to mention,
I am forced to the conclusion that such plants rarely if ever
form coal, the basis of coal being essentially wood, of what
kind, however, I will not at the present stage of the inquiry
venture to mention, but I will state thus far, that it approaches
more nearly to that of the Coniferee than any other wood ;
because in the Conifer, as we know them in this country,
there are few if any vessels or ducts in the woody part
of the trunk, but occasionally cellular tissue in what are called
the turpentine vessels, the entire bulk being woody fibre.
Such is the case in coal. In all the sections that I have
examined of undoubted coal, I have as yet found no trace of
a spiral vessel or a dotted duct, but in one or two instances
where the woody structure has been very evident, as shown in
Plate V., fig. 3, the fibres were evidently dotted.

External Appearances of Coal.—These must be so well
known to most of you, that I need not dwell further upon
them than to particularise one or two kinds which approach
nearest to the Torbane-hill mineral in general appearance.
The most remarkable of these is from Methil, in Fifeshire,
and known as the Brown Methil. So peculiar is it, that
when scratched with a knife, the streak is brownish-black

From the Coal Measures of Torbane-hill. 41

in colour, somewhat resembling that of the mineral. There
is also another variety of coal, termed the Black Methil, but
in this the streak is black, as in all other coals. _Yet the
microscopic characters of both these varieties are very similar,
and differ in no respect from coals generally. A curious fact,
however, I learnt from the chemists in Edinburgh, that the
composition of the Brown Methil came nearer to that of the
Torbane-hill mineral than any of the other known coals did ;
a fact which is borne out by the similarity in their external
appearance,

Examination of Coal by the Microscope.—If a small cubical
block of any kind of coal be examined under a power of
50 diameters, four of its six sides will exhibit more or less of
a fibrous structure, precisely like that of wood ; the other two
sides, if perfectly flat, will appear bright and polished, and
show very little structure: these correspond to the transverse
sections of wood. ‘Treat the Torbane-hill mineral in the same
way, and how very different are the results! Nearly the
same structure will be found on all its sides, but in none is
there the least trace of a fibrous arrangement.

Examination of Sections of Coal by the Microscope.—lf a
section of any well-known coal, cannel or otherwise, be
reduced sufficiently thin to be transparent, a work sometimes
of considerable labour and difficulty, it will be found to ex-
hibit one of two structures, according to the direction in which
the section has been made. These, for the sake of distinction,
may be called the cellular and the fibrous; the first corre-
sponding with a horizontal section, the second with a
vertical section, of wood. If it so happen that a section
taken at random from any specimen of coal should exhibit one
of these structures above named, by cutting at right angles,
the other will be found. Thus, for instance, if the first section
should correspond to a horizontal section of wood, the cut at
right angles to it will correspond with the vertical one; and,
of course, if the section be an oblique one, an intermediate
structure would be observed. ‘This remarkable fact is con-
stant in all the coals I have examined, and a knowledge of it
enables the observer to tell at once whether any section taken
at random was a horizontal or a vertical one. How strangely
different this from the Torbane-hill mineral! Cut that mineral
in any way you please, and there will be little or no difference
in appearance. The structure of the transverse sections of coal
is so very peculiar and so characteristic, that I must briefly _
point out the means it affords of distinguishing coal from any
other modification of vegetable tissue. The peculiarity con-
sists in this,—that, in the midst of a black opaque ground,

VOL. I. e

42 Structure of a peculiar Combustible Mineral,

numerous brown transparent rings, each having a black dot
in the centre, are interspersed ; they appear like transverse
sections of thick-walled cells or of woody fibres. In some
coals they occur in close proximity to each other, as in woods
generally: in other cases they are more or less separated,
either by the black material before alluded to, or by a network
of rather smaller rings, in which the central dot is absent,
There are many coals, especially some of the common domes-
tic kinds, in which it is difficult to recognise this structure in
every part of the section; in these-coals a rich brown struc-
tureless material—bituminous or not I cannot say—seems to
be in excess, and so obscures the characteristic appearances of
the rings. In longitudinal sections the woody fibres are
generally well seen, and a tendency to split in the direction
of their length (as shown in Plate V., fig. 5), may always be
observed. Amongst the fibres may be noticed certain elon-
gated cells, of a rich brown colour, having a dark line running
down through the centre: these are constant in all coals, and
when divided transversely, appear as the rings before noticed.
Their size is tolerably uniform in many coals (as shown in
Plate V., fig. 2). Mr. Witham was acquainted with the
differences between a longitudinal and a transverse section of
coal, as may be seen on referring to the 2nd edition of his
work on the “ Fossil Vegetables of the Carboniferous and
Oolitic Deposits ;” both the rings and the elongated cells are
well figured, and his remarks on the value of investigating the
microscopic structure of coal, are very excellent. ‘The absence
of vascular tissue in the numerous sections of coal, made both
by Dr. Adams and myself, would lead to the supposition that
the wood of which it is composed must approach very near to
that of the Conifere.

Examination of the Powder of Coal.—When coal is reduced
to a fine powder, and examined either in water or in Canada
balsam, it will be found to consist principally of short opaque
cylinders or fibres, occurring singly or in bundles, and of
angular dark-brown plates of various sizes, probably composed
of bituminous matter (as shown in Plate V., fig. 7); the
remainder of the mass is made up of minute transparent
particles of silica, with an occasional mixture of fragments
of cells and fibres. Many blocks of coal have a fine dull
black powder on two of their outer surfaces, which will make
the fingers very black: this I call the charcoal layer, and in
it will be found fragments of woody tissue of cells, and even
of vessels. My investigations lead me to believe that this
layer is derived from plants which existed at the same time
as the coal-wood, but were not capable of being converted

from the Coal Measures of Torbane-hill. _ 43

into true coal, but having been subjected to a great heat,
their remains are left as a species of charcoal. Some speci-
mens of the Torbane-hill coal have a large amount of this
charcoal upon their upper and under surfaces, and in it, vessels
of various kinds will occasionally be found, although such
vessels do not occur in the solid coal itself.

Examination of the Ash of Coal—TVhe brown ash of coal,
with the exception of particles, probably of silica, is almost
wholly composed of vegetable remains, some of which pro-
perly belong to the coal itself, whilst others are derived from
extraneous plants which have been mixed up with it. Every
kind of tissue which has been described as proper to the coal
may be met with in the ash, when not too much burnt. The
remains of woody fibres and cells are the most common con-
stituents, but flat, very opaque, irregular masses, such as are
shown in Plate V., fig. 4, and which evidently correspond to
portions of transverse sections of wood, are frequently found.
Portions of siliceous cuticle, probably of grasses, as shown
in fig. 6, from a drawing by Dr. Adams, are far from being
uncommon. In short, when the indications of the woody
structure of coal are very faint in sections, they are well ex-
emplified in the ash. Sections of Welsh Anthracite (which
I believe to be a fossil coke) are most difficult to obtain, and
when made, afford very unsatisfactory evidence of vegetable
structure: when, however, the ash is examined, the presence
of woody tissue is unquestionable.

The Torbane-hill mineral has been most carefully examined
by my friend Dr. Adams, and as his investigations were car-
ried on independently of mine, it will be satisfactory that you
should be made acquainted with the conclusions he has ar-
rived at after a laborious series of examinations. They are as
follow :—

‘¢ The most interesting example which could be adduced, illustrative of
the differences in essential characters, as demonstrated by the microscope,
between substances supposed by commercial men to be identical, is found
in the Torbanehill mineral, known also by the name of Boghead coal. In
the lawsuit previously alluded to, much of the scientific evidence regard-
ing this mineral was of a very conflicting character, so much so that the
court virtually set aside the scientific evidence, and decided on the legal
merits of the commercial bargain.

“The importance of the interests involved, and the high character of
the witnesses examined, have made this trial very celebrated ; and it is
from an excusable desire that the grounds of the opinion I expressed at
the trial should be understood, that I now seek to place them on record.
I will, however, confine my remarks to a very short summary of my
observations made upon the Torbanehill mineral, leaving a fuller detail
with my friend, Professor Quekett, who gave joint evidence with me, and
with whom I have discussed and investigated the whole subject of my

ee

44 Structure of a peculiar Combustible Mineral,

present communication with a most pleasing and perfect accordance of
observation and opinion.

‘¢ The following are the principal results :—

“¢T, A very thin section of the 'Torbanehill mineral, when viewed by
transmitted light, has a pale-yellow colour, is semi-transparent, and, with
the exception of very slight variations in the depth of the colour, probably
dependent on the varying thickness of the section, it appears to be a
uniform homogeneous mass. The same appearance is constantly presented
notwithstanding that the sections are taken in various directions. While
this is the usual appearance of what may be termed the average specimens,
viz., of portions taken from the centre of the block (or seam), yet, in
sections taken from near the outside, or lower portion of the seam, I find
a, quantity of small opaque particles (evidently earthy matter) in the form
of a fine powder, scattered through the yellow-coloured medium forming
the mineral. In such specimens the transparent yellow substance forms
irregular rounded granules, and the opaque powder is either sparingly
diffused over, or forms an outline or partition, more or less perfect, around
the exterior of the yellow granules. These granules vary much in size,
being as small as 1-4000th of an inch, and of every intermediate size
from that up to 1-200th of an inch in diameter.

*¢ In sections taken from the outside, as above described, I have observed
oceasional patches of opaque material of every irregular form, and which
I could not liken to any other substance, unless I spoke of them simply
as specks of dirt. In the same sections I have also found stalks of plants
and fragments of wood. ‘These opaque patches and vegetable fragments
are always distinctly isolated ; that is, they do not in any way resemble
or form part of the substance of the mineral, otherwise than by being
involved or contained in it, and their presence, therefore, can only be
considered accidental.

‘‘ IJ. When reduced to a fine powder, and examined under water, all
the particles of the mineral have a clear, and generally a sharp outline,
are of an irregularly rounded form, and may be described as of a uniform
granular appearance. About 7-10ths of the granules are very translucent,
and of a light amber or yellow colour. About 2-10ths of the particles
(also translucent) partake more of a flat, angular shape, and are quite
colourless, probably consisting of siliceous matter. The remainder of the
powder consists of dark semi-opaque particles. ‘

‘*¢ In specimens of powder taken from an outside portion of the mineral,
there is observed a larger proportion of the semi-opaque particles, together
with the occasional appearance of vegetable stalks, rough fibrous frag-
ments, and delicate fibrils of microscopic plants. With these special
exceptions, the powder gives no trace whatever of organic structure.

“ TII. The ash of the mineral, when examined under water, presents a
considerable quantity of the colourless particles already described, lying at
the bottom of the fluid, while a filmy particle of transparent particles floats
on the surface. No trace whatever of organic structure is here observed.

“« Polarised light does not in any way affect the appearances of the
mineral.

I have, in consequence of these investigations, a firm conviction of the
non-identity of the Torbanehill mineral with coal, setting aside those
differences which may be found to exist under mineralogical, geological, or
chemical investigation. JI cannot conceive how the evidence of Amorphisin
in the one case, and of intimate vegetable composition and of regular
structure in the other, can be explained away, or any other view than
that of non-identity of physical structure. In coal we find a well-
characterized organization, or regular arrangement of its component parts

from the Coal Measures of Torbane-hill. 45

so distinctly peculiar, that I should question the competency, at Jeast, of
any party who, after comparing the microscopic appearances of the two
substances in question, could hint at a resemblance. The Torbanehill
mineral, on the other hand, is as thoroughly devoid of organic structure,
or of any rezular arrangement of its component parts, as is a mass of
jelly or a conglomerate of masons’ mortar.”

I will now, in the third place, proceed to read the evidence
given by the witnesses for the pursuer and the defender.

Professor QUEKETT.—LHxamined by Mr. MACFARLANE.

You are one of the Professors in the Royal College of Surgeons in
London ?—Yes.

What chair do you occupy ?—The chair of Histology.

What is the object of that study?—An examination of the minute
tissues or structure of plants and animals.

I believe you have devoted a great deal of study and attention to that
subject ?—Yes, for the last twenty years.

You have published a catalogue of the preparations in the College of
Surgeons of London, descriptive of the various tissues ?— Yes.

And you have yourself a very extensive collection ?—Yes, I believe the
largest in Europe. 3

You conduct your investigations with the aid of the microscope ?—Yes.

And have you made careful investigation into the structure of the
various coals, as well as other minerals P—Yes.

Have you in this way had occasion to examine the most of the known
coals in England and Wales ?—Yes, about seventy varieties.

Have you also examined varieties of Scotch coal >—Yes.

What have you discovered to be the tissue of coals ?—They show us a
woody tissue.

Have you found structure of that description in all the varieties to
which you have referred >—AlIl the varieties of coal.

More or less distinct, I suppose >—Yes.

Now, have you examined the Torbanehill mineral ?—Yes, in every
possible way microscopically.

Were specimens of the mineral delivered to you ?—Yes, some time ago.

By whom ?—By Mr. William Forbes and a Mr. Rettie. I have the
specimens here.

Now, did you subject those specimens to a very careful examination ?—
Yes, very careful.

You tried them in every possible way, and repeatedly ?—Yes, and
repeatedly.

Did you make a great many sections out of them ?—Yes, an immense
number.

eo as to give you every possible opportunity in tracing their structure ?
—Yes.

What result did you come to?—That the Torbanehill mineral is dif-
ferent from anything that I ever saw in my life before.

Did you discover any trace of organic structure P—Yes, when plants are
accidentally mixed with it.

You were enabled to ascertain when it was so ?—Yes.

Perfectly ?—Perfectly.

But in the substance itself ?—No structure—that is, what the micro-
scopists would term an organic structure.

Is it different in that respect from all the varieties of coal you have
examined ?—Decidedly so.

46 Structure of a peculiar Combustible Mineral,

Did you get illustrations P—Yes, I have illustrations. (Produces same.)
I think you will come to a better understanding of the thing from those
illustrations than from the specimens.

’ Explain what that is (referring to illustration shown to the jury).—This

is a section of the Torbanehill mineral, or rather a granular section, and in
it you will observe some yellow matter that burns—whether bituminous or
resinous you must go to the chemists for. The black part is the strictly
mineral part.

What is the mineral matter to which you refer ?—It is the dark granular
matter.

Lord-President,—I understand that these illustrations show the bitumen
and the mineral at different places ?-—Yes, my Lord. »

Mr. Macfariane.—Now, then, do the illustrations of your coal investi-
gations exhibit a different appearance ?P—Decidedly.

Now, you say the mineral substance there is granular, is it so in the
coal?—Not at all, except when visible to the naked eye. In coal, you
can see mineral structure by the naked eye, but to that I do not allude;
but under the microscope you can tell that is a totally distinct thing from
the coal itself. What I mean is, that in specimens of coal you can often
see crystallized matter with the naked eye.

Is that extraneous P—I would say so.

But when subjected to the microscope ?—It exhibits a totally different
structure. It is not granular; it depends entirely on which way the
specimen of coal is cut. If cut in one direction you will either see a
cellular or fibrous appearance.

Indicative of what >— Woody tissue.

You have, I suppose, made sections in all the specimens of the Torbane-
hill mineral—in all the various ways you have made sections of the coal ?
—Yes.

And you have found in all the different sections a decided difference,
showing them in your mind to be different substances ?-—Certainly.

Then, judging from all your experience and investigation, do you con-
sider this Torbanehill mineral to be a description of coal or not ?—Certainly
not.

Have you any illustrations of coal there ?—Yes, I have a most remark-
able illustration—perhaps the jury will understand better by this than
anything else. JI have here a section of the mineral and coal in juxta-
position ; this has been cut by Mr. Bryson, lapidary, and you will be
enabled to see whether coal or mineral. The woody section is shown by
the dark colour, the mineral by the other.

Are those illustrations of longitudinal, or transverse sections, or what
sections P—That of coal is longitudinal, and of the mineral it is supposed
to be the same, because they are in juxtaposition.

Suppose a transverse section—what differencer—In the Torbanehill
mineral a section at right angles would present precisely the same cha-
racter, but the coal would present another character, that character being
shown in this lower drawing (exhibiting it to the jury). You will notice
that the coal runs through that mineral. You can trace it by its minute
tissue.

You examined some of the Scotch varieties of coal?—Yes, many
varieties.

Did you examine the Methil?—Yes, of two kinds, I believe known by
the names of the brown and the black.

Did you discover vegetable structure there ?— Yes.

Decidedly in both ?—Decidedly in both.

And in that respect different from this Torbanehill mineral ?—Certainly.

from the Coal Measures of Torbane-hill. Aq

You mentioned at one time that you had observed the presence, in some
of those coal specimens, of fossil plants ?—Certainly.

Could you see them with the naked eye?—Yes, in those specimens of
the Torbanehill.

Have you seen them. in coal in the same oa ?—Yes, but I consider
them extraneous or isolated examples.

Cross-examined by Mr. Neaves.—Is the structure of coal uniform in
general?—It is so tar uniform that the various transverse sections are
uniform, and so are longitudinal.

Equally visible in all places of the coal ?—Yes, in all places, except, as 1
have stated before, where you have mineral that is foreign to the coal.

What mineral matter do ie allude toP—The chemists must decide
that.

You only speak to appearances rP—Yes,

And the same formation in all?—Yes; the plants differ; I believe there
are two kinds of plants or tissue that essentially form coal,

But they present the same appearance ?—Yes, but those plants are not
traceable in the same specimens of coal. ‘That in the neighbourhood of
Glasgow may be different from the coal found in the neighbourhood of
Edinbur gh.

Can you distinguish the one plant from the other?—Yes, in the longi-
tudinal section.

And you never found any portion of any coal without exhibiting the
same permanent structure ?—Certainly not.

Where did you get that specimen you showed us of the two coals
together ?—That was taken by Mr. Bowerbank from the mine two or
three days ago, and the drawing was taken from a magnified representation
of one of the sections.

Lord President.—Let us take down what those specimens are if they
are to go in, but I thought they were to be taken away by the witness.

Dean of Faculty.—No. 25 represents that yellow matter of which the
witness spoke; No. 26 is the drawing of that highly-magnified section ;
Nos. 28 and 29 are the specimen and the drawing; and No. 27 is the
appearance presented by the two different sections of coal itself, the one
longitudinal and the other transverse.

Witness.—There is one thing I would wish to state, this—I came here
to speak the truth, and it may be testimony for or against my evidence,
when I say that all that which may be supposed like vegetable structure
in the Torbanehill mineral disappears when the structure is thin.

Dean of Faculty.—When you speak of that which appears as vegetable
structure, you mean those isolated fossil plants?—Yes. I would also
allude to the fact that a book was published in this city twenty years avo,
by Mr. Witham, of specimens made by Mr. Nicol; and this was the first
representation of this vegetable structure.

Dr. JAMES ApAMs.—ZHaxamined by Mr. MAcrarLane.

You practise as a medical man in Glasgow P—I do.

Have you devoted a good deal of time ‘and study to observations by the
microscope ?—I have.

For a considerable time back ?—For many years.

re you subjected to examination by the microscope various minerals ?
—I have.

Extensively ?—Extensively.

Varieties of Scotch coal P—Yes, a great many.

Most of the known varieties ?—-Most of the known varieties.

Have you examined the Torbanehill mineral ?—I have.

48 Structure of a peculiar Combustible Mineral,

Recently ?—Recently.

And did you subject it to a very careful investigation ?—Very careful.

In various forms ?—Yes.

Now, will you tell me what those Nos. of process are, No. 259 to 263,
both inclusive ?—259 represents sections of various specimens of the Tor-
banehill mineral, as seen under the microscope.

From the centre of the same, from the outside or bottom, and also from
the outside of block P—Yes.

What is the next No. ?—260, representing two sections of coal, termed
to me cannel coal—Duke of Hamilton’s cannel coal; the one represents
what I have termed a longitudinal section, and the other a transverse
section, drawn by myself.

The next No.?—Is 261. This represents a drawing of what was
termed to me Lesmahagow, Ferguson’s cannel coal—two sections drawn
from specimens made by myself; but the drawing made by an artist
named Donald, of Glasgow, under my eye.

And you have no doubt they are correctly done ?—No aouths very
faithfully made.

The next No. ?—262, representing sections of—1st, what is termed
Jordanhill cannel coal. The one is longitudinal of Jordanhill, the other is
a transverse section of a coal called Cowdenhead, given tome. This one,
263, which represents three drawings—two transverse and one longi-
tudinal; a transverse section of Jordanhill cannel coal, drawn by a
medical gentleman of the name of Risk, under my eye, a faithful delinea-
tion ; the other is a drawing of cannel coal procured from the Glasgow
Gas Works, called Knightwood coal; and there is also a longitudinal
drawing of Knightwood. Those three drawings were made under my eye
by Mr. Risk.

Did you subject the powder of the Torbanehill mineral to the micro-
scope ?>—I did.

Having applied a little water ?—Yes.

What did you discover to be the particles?—Those particles have a
clear granular shape, they are of an irregular rounded form, and I say
may be described as exhibiting an uniform granular appearance.

Any further description ?—About 7 of those granules are very translu-
cent, and of a light-amber colour. About #%, also translucent, partake
more of a flat or angular shape in their outline, and are quite colourless ;
and there are a few particles of a dark or semi-opaque matter.

Now have you examined coal specimens in the same way ?—I have.

What were the results ?—They differed very materially ; the particles
of cannel coal which I took as being the more compact coal, are found of
various sizes, and in form generally flat, angular, or oblong, with fibrous
character; the edges generally rough and as darkly opaque as in the
centre.

Have you examined the ash of the Torbanehill mineral ?—I have.

When you said that the coal particles were of different sizes, were the
particles of Torbanehill mineral of various or the same size When I
examined them under a high power I found the Torbanehill to be also of
various sizes.

You examined them with the aid of a microscope carefully ?—Yes.

What results?—I found it very difficult to describe the appearance,
because it seemed to consist of a film or congeries of structureless particles.
I got nothing tangible almost to lay hold ‘of. Iconsider most of those
consisted of the colourless particles which I have mentioned as having been
found in the powder, viz., the flat, angular, and perfectly transparent
particles.

from the Coal Measures of Torbane-hill. 49

I understand, Doctor, when you say perfectly structureless, that there
was no organization ?—No organization ; they have form.

No trace of vegetable origin >—None.

Nor the coal ash?—In the coal ash examined under water, I found
abundant remains of vegetable structure, examined in the same way.

Woody tissues in the coal ?—Yes.

Did you conduct your investigation of the ash of the Torbanehill
mineral and of the coal both in direct and transmitted lights >—By both.

And with the results which you have described P—Yes.

Were they the best, most approved instruments ?—They were. I have
used various instruments of all kinds, but I have used the best and most
recent construction.

What were those ?—Those were prepared by two of the most eminent
London opticians, Mr. Ross and the firm of Smith and Beck.

What conclusion do you arrive at in regard to this Torbanehill mineral,
keeping in view your investigation of the sections, of the powder, and of
the ash ?>— That the two substances are totally dissimilar.

That the Torbanehill is a different substance from any coal with
which you are acquainted r—Yes. -

Cross-ecamined by Mr. Neaves.—Are you in practice in Glasgow as a
physician P—I am.

Have you marked the magnifying power of the instruments used on
those specimens P—I have. .

When did you first see this mineral?—I think on 15th January last

ear.
q Had you never seen it before -—Never to my knowledge.

You had previously been in the habit of examining coals p—I had.

And had seen all the cannel coals P—Not then. Ihave since examined
them.

What coal had you seen when in the practice of examining before >—
Chiefly domestic coal.

For many years ?—For several years.

With any particular view ?—None.

The body and ash of domestic coal ?—Yes.

You always see the woody structure in the ash ?—Always; I have
never failed.

And in the coal ?—Do you mean the sections ?

Yes.—I have never met with a piece of coal that had not those
appearances.

Do you give it a name ?—I call it a fibrous section, from appearing like
a bundle of fibres in one direction. I give it longitudinally, because it
gives me the idea of length, and annular, that is, composed of rings,
when seen in a cross cut with a longitudinal.

But are equally distinct in the same coal always?—Not equally
distinct.

Not equally distinct in all coals nor in the same coal ?—No, but remain
always distinct in every coal.

Re-examined by Mr. Macfarlane.—Have you been at Torbanehill ?—Yes,

And made specimens ?—Yes.

Did you examine from those specimens ?—Yes.

Fair or average specimens of the mineral ?—I took them just as they
were raised from the pit, and examined them from the centre, outside,
and every way I could possibly conceive.

Your observations have been more recently directed to cannel coal p—
Yes.

Can you give me the names ?—I believe I have examined about forty or

50 Structure of a peculiar Combustible Mineral,

fifty different specimens, as far as I know, but I can give the names of
different coals that I tested.

Just give us a few ?—These were Capeldrae, Wemyss, and Pirniehill,
wc.

Your investigations had been previously chiefly directed to the ordinary
coals ,—Yes.

Is it more difficult to trace the organic structure in the cannel coal than
in the ordinary domestic coal ?—It is.

Perhaps requires more skill and practice ?—Yes, in conducting the
investigation into the cannel coal.

What is the reason of that?—The reason I believe to be, that the
structure is much more compact in the cannel coal, and the section requires
to be made exceedingly thin, and it is very difficult to procure that con-
dition, from the excessive brittleness of the material, and also intense
opacity, and containing particles of hard matter, which frequently tear
out the specimens.

Mr. BowERBank.—Lxamined by Mr. MACFARLANE.

Mr. Bowerbank, you live in London P—I do.

You have given a good deal of your time and attention to microscopical
observations ?—I have for these twenty-five years past.

You are a fellow of the Royal Society ?—I am.

You were lately president of the Microscopical Society of London ?—
I was.

And you have written on the subject, I believe ?—I have.

Have you made a great many examinations, with the aid of the micro-
scope, of mineral substances P—I have.

Of various descriptions of coal ?—I have. For many years, the subject,
simply as a natural-history subject, was much inquired into.

And you have turned your attention to it >—I have.

And have for several years been taking observations, with the micro-
scope, of coal substances P—Yes.

Have you been at Torbanehill ?—I have.

Recently ?—Yes, recently.

And you obtained specimens of the mineral that is working there ?—I

And subjected them to examination Pp—I have.

Did you give a specimen last week to Professor Quekett P—I showed
him a specimen, and he desired to possess it for examination.

And did you give some specimens to Dr. Adams ?—I did.

What has been the result of your examination of coal substances ?—
Every coal which I have examined, either bv sections, or by external
characters, or by the examination of the ash, has convinced me that it is
an essential character of coal that it should be composed principally of
organized vegetable substances and bitumen.

Lord President.—Of what, did you say ?—Of organized vegetable
carbon and bitumen principally.

Mr. Macfarlane.—With a little earthy matter p—Yes.

I think you said these examinations were of the sections of the sub-
stance, and of the ash as well ?—Of the sections of the coal matter, and of
the ash as well. The practice generally adopted in examination is, first
to observe its ordinary characters, and next its sections, so as to develop
its structure.

Have you pursued the same mode of investigation in regard to the
Torbanehill mineral ?— Exactly.

And with what result ?-—I have found no organic structure in it,

from the Coal Measures of Torbane-hill. 51

although I have examined it by powers varying from 40 or 50, up to
very nearly 700 linear. I have also examined the ash with great care ;
and I may say that as to almost every specimen that has passed through
my hands identified, and others as well, in no case have I found any
indications of vegetable structure in the ash.

Then the results of your examination of the coal, and of this mineral,
are very different ?—Quite opposite.

I suppose, Mr. Bowerbank, you have used the best instruments p—Yes,
Sir, I believe there are no better to be procured. Indeed, unless they
were instruments of a high optical character, they would not develop the
minutest portions of the tissue satisfactorily.

Who are the great London makers ?—Ross, Bowell and Smith, and
Bett (or Beck).

You have examined, I suppose, different varieties of shales, have you ?
—To a very considerable extent.

Any traces of organic structure in them ?—Not in the body of the
shale itself, but a oreat intermixture of isolated plants. In fact, in coal
shales isolated plants form a considerable portion of them.

We have had the word ‘ amorphous’ used frequently, Mr. Bowerbank.
Can you explain its meaning ?—I understand an amorphous mass of
that description to be a mass without crystallization—a mass which
would cleave in any direction without any determinate arrangement.
For instance, I would say a sandstone, although formed of granulated
masses, is still an amorphous mass, as there is no determinate arrange~
ment.

Where there is organic structure, the word amorphous would not, of
course, apply ?—Not to the structure itself, but it may apply to ‘the
medium in which that structure is imbedded.

Cross-ecamined by Mr. Neaves.—Where did you get your specimens ?
—Some from Torbanehill pits, which I visited within the last week.

And adjoining properties ?—And some from the adjoining properties as
well.

What property was that ?—Bathgate pit, and another pit. I also
received verified specimens sent from the country to request an examina-
tion of them.

You first saw the mineral there ?>—I first saw the mineral at Queen-
wood College, some time ago.

Some months ago ?—About three months ago.

Re-examined by Mr. Macfarlane _—Among other coals have you
examined various cannel coals ?—Frequently.

And the statements you have made have had reference to them as well
as to others ?—The specimens which I have examined of the cannel coals,
vary very considerably in character from this new mineral from Tor-
banehill.

You discovered the vegetable origin of the structure in them ?—Oh,

yes.
This closes the evidence of the microscopists on the

pursuer’s side. I will now proceed to read that given on the
side of the defender.

Professor J. H. BALFour.—Haxamined by My. NEAVEs,

You are Professor of Botany in the University of Edinburgh ?—Yes.
And [ understand that you have. devoted attention not only to the sub-
ject of botany as concerns existing plants, but also to fossil botany ?—Yes.

52 Structure of a peculiar Combustible Mineral,

Is that a part of the course that you teach P—Yes.

In the course of teaching that class, are you in the habit of examining
mineral substances with a view to noticing their structure ?—I examine
fossil plants. I have a large collection of specimens of fossil plants.

Have you been in this case shown some specimens of different minerals
with a view of examining them ?—Yes.

What were they ?—I have seen specimens of the 'l’orbanehill coal, the
Methil coal, the Capeldrae coal, the Lesmahagow coal, and several other
parrot and other common coals.

Did you visit the ground at Torbanehill >—Yes, I went to the pits and
examined the coal, and brought specimens from the place.

Did you visit the Methil pit ?—Yes.

And got some specimens from Methil ?—Yes, out of the pit.

And where did you get the other specimens that you refer to?—I got
them from various sources. Some were sent me authenticated by Mr.
Russel, some were given me by Dr. Maclagan, also by Dr. Redfern, Dr.
Aitken, and Professor Harkness.

Did you make sections of these minerals with a view to a microscopical
investigation of them r—Yes.

Did you make such a variety of sections as to enable you to judge in all
directions P—Yes, so as to judge fully of the structure.

Now, from that examination, are you able to say whether you dis-
covered in these specimens traces of organic structure -—Certainly organic
structure.

In all the specimens ?—In all the specimens more or less.

Now, in the Torbanehill mineral did you find marks of organic struc-
ture ?—Certainly.

And in the Methil ?—And in the Methil.

Was there any difference, or any resemblance, between the appearance of
the Torbanehill mineral and the Methil mineral?—A remarkable similarity.

Was there some Lesmahagow coal ?P—Yes.

And some Capeldrae also ?— Yes.

And I think some Kinneil coal ?—Some Kinneil.

Which is a cannel also P—Yes.

Did you take the assistance of Dr. Greville ?—I took his assistance in
delineating what we saw under the microscope.

Did you see his delineations ?— Yes.

Did they appear to you to be successful ?—Most correct, I think.

You believe coal generally to be a vegetable formation, I suppose ?—
Certainly.

Of what species of plants is it generally supposed to be composed ?—The
coal plants are numerous. We have, in the first place, a mass of ferns,
stigmarias, sigillarias, lepidodendrons, calamites, and various other genera.

The ferns supposed to form coal-beds are very gigantic ferns compared
with the present ferns ?—They are tree ferns.

Is it a cryptogamic plant Pp—Yes.

In such plants, what is the particular appearance or structure you
would expect to find ?—In all these plants, as well as in other plants of a
woody stem, we have cells and vessels; but in the tree ferns we have a
structure which may be said to be pretty regular, which is called scalari-
form, or ladder-like, from the bars visible upon it. They are vessels or
tubes.

Did you see in the Torbanehill coal appearances that seemed to you to
indicate cellular structure p—Certainly. :

No doubt of that >—No doubt of that.

And also some appearances indicative of scalariform structure ?—Yes.

from the Coal Measures of Torbane-hill. 53

The cellular appearances more generally diffused than the other ?—Yes,
much more generally.

Do you consider you have in that way evidence of the vegetable compo-
sition of the Torbanehill mineral ?—Yes, certainly.

And of the same character generally as the other cannel coals that you
examined ?—Precisely.

[Here several drawings were handed to the witness, and he was asked to
explain them.

In the first drawing, which was of the Torbanehill mineral, witness
stated the sections showed the vegetable structure, and also the scalariform
vessels, with the bars upon it, very distinctly.]

Is that the kind of structure that is seen in modern tree ferns >—Yes.

The next drawing exhibits three sections,—the Lesmahagow, the Capel-
drae, and the Torbanehill coal,—showing precisely similar structure. They
are a little different in colour, but the same in structure. There are also
sections of the Torbanehill and Methil in the drawings, showing the same
appearance and structure in both these. Another drawing of the separate
individual shales shows distinctly the appearance of separate cells, both in
the Torbanehill coal, in the Lesmahagow coal, and in the Capeldrae coal.
And, in fact, we find these in various other coals.

The cell is the base of the organic structure of these vegetables P—Yes.

It is the accumulation of cell upon cell that builds up the structure p—
Yes.

Judging microscopically, then, and also with your knowledge of fossil
botany, would you draw the inference that the Torbanehill was of the
same, or of a different class of substances from the other cannel coals that
you have mentioned P—The same class as of the cannel coals I have seen.

The only difference, I understand you to say, is the difference in the
tinge of colour ?—Yes, and that occurs in many coals.

You don’t think that essential in deciding the question P—I do not.

- Cross-ecamined by the Dean of Faculty.—These observations are made
upon a thin section ?—Yes.

Who made the sections ?>—They were made by Professor Harkness, Dr.
Aitken, Dr. Redfern, and Mr. Glen.

Would you mark upon each the name of the gentleman who did them ?
—Yes, to the best of my recollection.

{Here witness marked each section as requested. |

Have you yourself been accustomed to make such sections P—I have
made sections for the microscope.

Have you much practice with the microscope ?—Yes, it is part of my
course.

In reference to existing plants ?—Yes, and also to fossil plants. I have
a large collection of fossil sections.

With regard to this drawing here [holding up one of those previously
described by witness], that represents the impression of an individual fossil
plant ?—That represents only a portion of a plant, the vascular part of the
vascular tissue of a plant, approaching nearly to the scalariform tissue.

Do you mean that the tissue is there, or the impression on the plant ?—
The tissue is there.

In this other portion of the seam, then, which is coloured brown, you do
not observe any structure ?—I did not examine particularly.

But does this represent what you saw on that occasion ?>—Yes.

Then there is no appearance of structure there P—I cannot say.

There is no structure represented there >—No.

All that you found in this particular section is the representation of part
of a fossil plant p—Yes.

54 Structure of a peculiar Combustible Mineral,

Part of an individual plant apparently P—Part of an individual plant
probably.

Do you know from what portion of this seam of Torbanehill mineral this
slice representing the upper drawing is taken P—I do not know the portion
of the seam.

Do you know the portion of the seam from which any of them were
taken r—I have only seen the specimens. They seem to be the ordinary
appearance of the Torbanehill mineral, and quite the usual appearance of
the coal, so far as I saw.

Here the Dean of Faculty took up another drawing, and asked witness
if he saw anything similar to that ?—I saw appearances similar to that.

Have you represented them ?—Represented them so far in some of these
sections, only the dark colour between makes a difference in the appear-
ances.

Lord President.—Is that in the Torbanehill mineral P—Yes.

Dean of Faculty.—Did you see anything like that [showing witness
another drawing, No. 25]?—Something approaching to this. It wants, in
some respects, the regularity of the structure I have seen in the other.

Shown No. 26, another drawing, and asked if he had seen anything like
that ?—This also approaches to what I observed, but wants the definiteness
and regularity of the structure I saw.

Did you see anything like that [showing No. 28, another drawing] ?—
Yes, the yellow part is more like what we saw in the general structure.

What power did you use in making these observations ?—They are
marked in diameters ; two of them were 200, and the other 70.

Have you ever examined shales in this way ?—I have looked at one or
two shales. It is not so much in my way as plants.

Do you find marks of fossil plants in them ?—Yes, they occur; but the
structure is different in them. They have not the same marked definite
form I have seen in the others.

I understand that in these you represent both the transverse and the
parallel sections ?—Yes, we have taken them in two directions.

Which are the transverse P—The three upper are the longitudinal, and
the lower the transverse or horizontal.

What do you mean by horizontal ?—By horizontal we mean cutting off
the ends of the vessels.

That is to say, you learned that from the gentlemen who made them ?—
I have examined sections.

You did not see the sections made ?—No.

Then, of course, you could only get the information from those gentle-
men who made them ?—Yes.

Are the three upper cut along the stratum, as it were, off the top of the
stratum as it lies?—I am talking of them as regards the appearances we
see in the microscope. Judging from ordinary structure, in the one case
we cut the ends of the vessels ; in the other, we cut along the line longi-
tudinally.

Lord President.—The three upper are cut along the line of the vessels,
and the three others are cut across the line of the vessels.

Dean of Faculty.—Do I understand you to say that you were told they
were cut in this way, and that that is the ground of your saying so; or do
you form your opinion by the appearance they present ?—I was of course
told so; and on looking at them, I should say they are so cut.

Then it is from both these reasons that you say so ?—Yes.

Did you examine any part of the ashes of this mineral with the micro-
scope P—No. ;

Did you ever examine the ashes of coal with the microscope ?—No.

from the Coal Measures of Torbane-hill. 5d

Did you use direct or transmitted light in these examinations P—I used
ec aaa transmitted light, but I also viewed some specimens by direct
light.

Re-examined by Mr, Neaves.—There are several drawings here. Did
you examine a great many more cuttings than these drawings ?—A great,
number. :

How many more, do you know ?—I cannot tell the number of the sec-
tions of Torbanehill ; at all events, some eight or ten, besides sections of
other coal.

And then made a drawing of these P-—-Yes, as being average specimens.

Did you see some of these sections made P—Yes, these were the sections
made under my direction by Mr. Glen.

The Methil section?—I cannot say I saw it made in the sense that
I saw the whole process gone through, but it was done for me, by my di-
rection, from a piece of Methil coal.

Lord President.—Did you see Mr. Glen make some of the sections ?—I
should rather say that the sections I allude to were made under my direc-
tion, and were authenticated by me at the time.

Mr, Neaves.—In the other sections of the Torbanehill mineral which
you have examined besides this, did you find the same appearances r—The
same appearances. -

I forget what you said as to this yellow part of No, 28 P—I considere
that to be a cellular structure.

The yellow part included ?—Yes.

This cellular tissue is a magnified appearance of the separate individual
cells P—Yes.

With the view of showing that they were at larger power ?—These are
cells which occur in these coals, and they are separated the one from the
other. We took magnified drawings of them.

Occurring at Boghead ?—Yes, and on the others.

And besides showing those things, you formed an opinion of what they
were ?— Yes.

That they were the indications of vegetable cellular structure P—
Certainly.

Lord President.—That is, the appearances in the mineral seams P—Yes.

Mr, Neaves.—Including the Torbanehill P—Yes.

And of that yellow part of the representation of the Torbanehill
mineral ?—I believe it to represent vegetable cells.

In these plants I suppose the structure is but imperfectly understood ?
—I may say we do not know it so completely as we know all the plants
of the present day.

The cells may be longer or shorter p—Yes.

They vary in their form rp—Yes.

And that may affect the longitudinal appearance of the cells ?—Yes.

I do not understand you to say that this is the mere impression of a
foreign fossil, but the actual structure of the mineral at that place ?—
Certainly.

Dean of Faculty.—The individual plant is there lying in the mineral ?
—The structure of the plant—not the entire plant.

A part of a fossil plant is seen there ?—Yes.

Mr. Neaves.—Forming a part of the coal ?—Yes.

Dean of Faculty.—I understand, Dr. Balfour, that there is a part of
the fossil plant here lying imbedded in something or other P—It is a quite
dissimilar part as regards the appearance.

The plant must be there in order to give it that appearance P—It must
be the structure appearing so distinctly as to be seen there.

56 Structure of a peculiar Combustible Mineral,

Very well; a plant is lying here upon another thing, which is here
represented by a dull-brown colour ?—Yes, a part of the plant.

Mr, Neaves.—What did you say ?—That that is part of the Sisetdaxe
of a plant which is lying there in the mineral. When you make a
section of the mineral you come upon this, showing you that there was a
plant.

At that part the mineral consists of that plant >—Yes.

Dean of Faculty.—You have seen fossil plants in stone quarries ?—Yes.

Mr, Neaves.—You do not consider that an example of such an appear-
ance ,—No.

Dr. ReprERN.—Haxamined by Mr. NEAvEs.

Dr. Redfern, you lecture on subjects connected with the microscope in
connexion with the University ?—Yes; and teach the use of the micro-
scope.

You are a Fellow of the College of Surgeons of London ?—Yes.

Have you been accustomed to the examination of substances by the
microscope ?—Yes.

Principally of vegetable substances for some years ?—I have for many
years been in the practice of examining vegetable structure by the micro-
scope.

Both in recent vegetables and in fossil substances ?—I have.

Did you lately receive some specimens of different minerals, including
some of the Torbanehill mineral ?—I did.

From whom did you get the Torbanehill mineral ?—I got some specimens
from Dr. Fyfe, and some others from the Aberdeen Gas Works, in the
presence of Mr. Leslie, the manager.

Did you subject these specimens of the Torbanehill mineral to micro-
scopical examination ?—I did so.

How many sections of it did you take ?—Eighteen.

From the same piece, or from different pieces ?—From eight different
pieces.

Did you or did you not find vegetable structure in these sections ?>—I
found vegetable structure in every section.

Have you examined different cannel coals with the same view ?—I
have.

What cannel coals ?—I have examined Lesmahagow cannel coal,
Capeldrae cannel coal, Wigan cannel coal, Methil cannel coal, and
Halbeath parrot coal; and also the Kinneil coal from Bo’ness.

In what way would you speak of the examination of these minerals,
and of the examination of the Torbanehill mineral, in reference to the
vegetable structure ?—I am quite convinced, that in the sections of these
different coals there are parts which cannot be distinguished from each
other.

Vegetable structure in all ?—In all.

And in some parts this mineral undistinguishable from the others ?—
Certainly.

The Boghead mineral has considerable varieties of aspect in itself 2—It
has.

Different shades of colour?—There are black, brown, and spotted
pieces—black pieces with brown spots.

In the lightish-colour portions of the Boghead mineral, what is that
you saw ?—I saw vegetable cells in these portions.

The structure that you saw is cellular structure ?—Yes.

Besides the cells that you saw, what else did you notice ?—I noticed
also woody fibre, or woody tissue.

From the Coal Measures of Torbane-hill. oT

Are there some yellow spots in this light-coloured portion of the
mineral ?—'There are.

What do you think these yellow spots indicate ?—They indicate the
existence of vegetable cells.

Have you applied any test to endeavour to find out whether they were
vegetable or not ?—I have, Sir; I have many reasons for concluding that
they are vegetable cells.

Would you mention your reasons?—lI find that they can be perfectly
isolated—they project upon the edges of all sections of the mineral—they
are rounded—they are as uniform in size as the cells of other vegetable
structures—the general appearance of the section is that of a piece of
vegetable cellular tissue—the yellow spots do not act upon polarised
light, or act upon it very feebly.

Generally speaking, do you consider that the Torbanehill mineral
exhibits the same appearances of structure and position microscopically
as the other cannel minerals ?—It does.

Did you see Dr. Greville’s drawings P—I not only saw the drawings,
but I saw him make them.

You had long previously examined the minerals ?—I had; long and
carefully.

Do these drawings appear to you to represent the general character of
the mineral P—They do. ;

And you believe these drawings to represent cellular tissue P—I do.

Your sections were taken at random from the general specimens that
you had P—Certainly.

As fair specimens that you thought the mineral would exhibit ? —That
was my chief object in obtaining them from the Aberdeen Gas Works.
I took the specimens for as fair average specimens of the Torbanehill
mineral as I could obtain.

And they would have supplied similar representations as those Dr.
Greville has given, in your opinion ?—I am satisfied of that.

Cross-ecamined by the Dean of Faculty You say Dr. Greville’s
drawings represent the same thing that you saw ?—They do.

Did you examine the ash of this coal ?—Yes.

With the microscope ?—Yes. I consider the examination of the ash as
liable to great sources of fallacy, and place no dependence upon it.

Your reasons?—I should not look upon the ash to make out the
structure it contains.

That is not your reason, but a repetition of your opinion. What is
your reason r—Because I would expect the greater portion of vegetable
structure, if it existed, to be destroyed by the process of combustion.

Did you ever examine the ash of ordinary coal with the microscope P—
I have not.

Dr. R. K. Grevitte.—Huamined by Mr. NEAVEs.

Dr. Greville, I believe you have devoted a good deal of your attention
to the study of botany ?—Yes, it has been the principal study of my
whole life.

And in connexion with that to the use of the microscope P—I may say,
without exaggeration, that for many years I have used the microscope
almost every day.

Among other branches of the vegetable kingdom, you have studied and
written upon the cryptogamic family, which includes the ferns ?—Yes.

And which requires particular use of the microscope in order to illustrate
its fructification?—Yes. I may add that 1 have made the drawings of
everything I have published from my own microscopical investigations.

a

58 Structure of a peculiar Combustible Mineral,

| made drawings of the outline and structure of two or three hundred
ferns alone,

Were you asked to assist some gentlemen using the microscope to
represent the appearance of some sections of minerals ?—Yes.

These are the drawings you made ?—Yes.

Did you yourself look at various sections of the minerals besides those
that you have represented ?—I did, especially with regard to the Boghead
mineral. {examined under the microscope eighteen different slices made
from eight different specimens of the substance.

Were these Dr. Redfern’s specimens ?—Yes.

Did you discover vegetable structure in these ?—Unquestionably, in
the whole of them.

Did you examine some other minerals—some cannel coals that this
gentleman had?—I examined all those coals of which the names are
appended to the drawings. There is the Methil, Lesmahagow, and
Capeldrae coals.

Now these are correct representations, to the best of your ability, of
what they present -—They are; they might be more minutely finished,
but they give, I hope, a fair representation “of the structure.

Did it appear to you, from your examination of these different things,
that they were the general structure of the mass, or any incidental
structure ?—I have no hesitation in saying that it was the general
structure of every specimen, not incidental. JI should consider it to be
quite impossible it could be incidental. .

Do you consider that there is a material difference or a substantial
identity between these different bodies, as represented in these different
minerals ?—I do not. I examined the specimens of the three upper-
most sketches, and the structure was so similar, that I considered them
to be identical. ‘There is a difference, but nothing amounting to any-
thing essential in the structure. The Lesmahagow, Capeldrae, and
Torbanehill are essentially the same. I may be allowed to add, that in
each slice there is a difference in every part of that slice, so that you
must be guided by the general view.

From your botanical knowledge, have you any doubt that these repre-
sentations exhibit vegetable cells ?—I have no more doubt of that than of
my own existence at this moment.

Will you explain what that paper is?—[handing witness one of the
drawings spoken to by Professor Balfour|—That drawing represents
vegetable cells in an isolated state, scattered throughout the substance, and
observable, I believe, in most coals—certainly in most coals that I have
examined. It is difficult to say what they may be, but I have no doubt
that they are vegetable cells, solitary cells. They may possibly be
transverse segments of cells, but I would not venture to say anything
more than that. I believe them to be vegetable cells.

Found in this mineral ?—We have found these vegetable cells in the
Boghead as well as in others. .

Will you explain what these two drawings represent °—{ handing witness
two of the drawings spoken to by Professor Balfour |—The uppermost one
represents cellular tissue in the Torbanehill mineral; and, upon the
whole, I consider that as one of the most satisfactory specimens which I
examined ; the cellular tissue is so unequivocally marked, and so regular,
that it may be compared to that of a recent plant. It is exceedingly well
defined. What I have represented in the drawing is not in the least
exaggerated. No person accustomed to botanical sections would hesitate
in believing that to be cellular tissue. The lower drawing represents a
beautiful specimen, but whether that is general in the mineral I could not

from the Coal Measures of Torbane-hill. d9

say. It represents a modification of the vascular structure of plants
called technically the scalariform structure. I can compare it best by
comparing it with an old basket. It is an unequivocal vegetable structure.

What occurs in its neighbourhood in the rest of the section ?—'This
was the whole that I saw. The other portion was not ground so thin,
and I could not see what it consisted of ; but judging from the traces of
these vessels at the extreme edges, I have no reason whatever to doubt,
that if the remainder of the section had been ground sufficiently thin, we
would have seen the continuation of that structure.

But the other cells that you described here are diffused through the
entire mass of the substance ?—In all the specimens I examined it was
uniform throughout the whole. It was exceedingly well marked in the
one that represents the transverse section of the cells.

You get the width of the cells more distinctly when you cut the
transverse section ?—You get the area more distinctly shown.

Cross-examined by the Dean of Faculty.—Can you explain to me what
are infusoria ?—Infusoria represent minute animals invisible to the naked
eye—visible only to the microscope.

Where do you find them P—It is very difficult to say where you do not
find them. Generally they are sought for in fluids.

You find them in minerals also?—I am not prepared to answer that
question. Iam not sufficiently acquainted with the subject to venture
to answer it.

Then you cannot tell me what appearance they present when found in
minerals when examined under the microscope ?—No, I am not aware of
their occurring.

Professor HaArKNEsS.—Hxamined by Mr. Youna.

Professor Harkness, you are Professor of Geology in Queen’s College,
Cork ?—Yes.

You succeeded Dr. Nicol ?—About six months ago.

You have devoted considerable attention to the study of geology ?—I
have.

And also to the examination of objects by the microscope ?—Yes, so far
as relates to fossil plants.

You have visited Torbanehill ?—I have.

You went down one of the pits >—I was down two of them.

And examined the mineral as it lay in the earth P—Yes.

And made yourself acquainted with its geological composition ?—I
found it to occur in the proper coal measures.

Exactly in the position you would expect to find coal ?—Decidedly so.

You found nothing whatever in its geological composition to lead you
for a moment to doubt that it was coal?—Nothing; on the contrary,
everything to induce me to believe that it was coal.

Did you form any opinion upon the mineral itself ?—-I formed the
opinion, that from the appearance of the mineral it was a coal.

Did you take some specimens of the mineral away ?P— Yes, I did, for the
purpose of making a more careful examination.

And after that examination you retained your opinion ?—I did.

And your opinion now is that it is a coal?—Decidedly so, without any
manner of doubt.

Did you make some sections of the mineral which you took away with
the view of microscopic examination ?—So far as regarded fossil plants.

Did you find the structure familiar ?—I found the structure peculiar,
and the fossils characteristic of the coal formation.

How many structures are there in coal and coal plant P—There are two

60 Structure of a peculiar Combustible Mineral,

or three distinguishing characteristics, first the woody fibre, the scalariform
tissue, and the cellular tissue.

Is this upon the examination of a great many sections?P—Yes. That
was generally, not mere accidental structure of particular pieces.

You saw a drawing made by Dr. GrevilleP—I was present when that
drawing was made.

Sah ‘that gave a sufficiently distinct idea of the course of examination ?
—Yes

Of the Torbanehill and some other coals p—Yes ; and the Lesmahagow,
Kinneil, Capeldrae, and some other cannels.

I believe the drawing was made from a section furnished by your—
That is a most beautiful ; specimen of cellular tissue.

This is the most beautiful specimen you have seen of woody fibre ?—I
distinguish woody fibre from cellular on account of the more regular
formation of the cells.

You have no doubt that this is a vegetable product P—Not the least.

{ Witness was shown the drawings illustrative of cellular tissue and
woody fibre, and distinguished each with great precision. |

You know what shales are >—Yes.

Do shales ever exhibit vegetable structure P—As shales they do not.

How would you describe a shale ?—There are several forms of shales.
Supposing the coal to be so mixed with earthy matter as to be incapable
of being used for fuel, then that would be called a coaly shale.

And when the coaly matter is so great in proportion to the earthy mat-
ter that it will burn ?—I should consider this a coal.

And more or less pure according to the admixture of earthy matter ?—
All coals contain more or less of earthy matter, and accordingly the coals
run into shales as the earthy matter increases.

When you come to a substance beyond which a substance will not
burn, you would call it a coaly shale ?—Yes,

It is very difficult to draw the line at the exact place?—Very difficult.

Has this mineral anything of the character of a shale P—Not the least,
so far as I have been able to detect.

You have seen specimens of Methil coal, and examined them with the
microscope ?>—Yes.

And did you find anything to distinguish the Boghead mineral ?—
So far as external appearance went, I could scarcely distinguish the one
from the other, and there was also a great similarity in internal structure.

There are a variety of cannels which approach each other very closely ?
—In regard to the distinction between the two there is not a more com-
mon one than this, the capability of burning and being used for the
purposes of fuel.

If the substance would burn, and could be used as fuel, you would say
it was a coal ?—Yes, I would.

If any substance ‘is sold in the market as a coal, is it a coal?—Yes, I
should think so.

There is no science against this >—None that I am aware of.

Cross-ecamined by the Dean of Faculty.—I suppose whatever comes out
of the coal measures and burns by itself is coal?—No; I would not say
that. You might get a fragment of bitumen, which would not be coal,
and that burns by itself.

Is that the only exception >—I am not prepared to say that there are
any other exceptions.

Fragments of bitumen would be an exception ?—Yes.

The way by which you distinguish a coal from a shale, or a shale from

from the Coal Measures of Torbane-hill. 61

a coal, I understand is, that the one will burn, and that the other will
not ?—The one will burn without the mixture of any extraneous matter.

It will burn by itself ?—Yes.

There are other distinctions ; but this is the distinction upon which you
rested ?>—Yes.

You were going to tell us that there were a number of kinds of shales.
Tell me some of these ?—There are some which are absolutely devoid of
coaly matter—clay shales, which have no coal in them at all.

Any other distinction ?>—Yes; there are shales which I should charac-
terize as bituminous shales.

How do they differ from coaly shales >—They differ inasmuch as they
give a bituminous smell when struck by the hammer; and they yield
bitumen to chemical solvents.

Do they burr ?p—Yes, they burn in some cases.

Where do you find most bituminous shales P—You find them in Cam-
bridge and in Dorsetshire, in the higher beds of the oolite.

Do you find the Methil coal to be of a laminated and slaty structure p—
I found some fragments that were laminated; but others present the
conchoidal structure that you have in the Boghead, and is compost.

The Boghead is compost ?—It is.

Is the Methil coal so ?—It is generally so.

But portions are slaty and laminated p—Yes.

Will you explain what infusoria are >—I have not given any opinion as
concerning infusoria. :

But you can give one ?—They are minute microscopic animals.

Where are they found ?—I generally find them in water.

Are they not to be found in mineralsP?—I have not found them in
minerals,

But are they not to be found in minerals ?—They are found in certain
mineral beds, but I have not found them in mineral beds.

Dr. Witu1am AiTKeN.—LHxamined by Mr. PENNEY.

You made some sections of the Torbanehill mineral, and of some other

coals P—Yes.

Were they for your own examination, or some that Dr, Greville drew ?
—TI did some, and also for my own.

You got the returns from Torbanehill ?—I did.

From the pit mouth p—Yes.

You made the sections fairly for the purpose of testing °—Yes.

Mr. Neaves then stated that they would not require to examine
Mr. Glen, as his sections were also admitted.

Having now read to you the evidence given by the micro-
scopists on both sides of the question, I cannot refrain from
making a few remarks on some of the statements of the
defender’s witnesses. ‘The subject to me is a painful one, for
it is always with feelings of regret that I venture to differ in
opinion from any scientific observer ; but, however contrary
to my inclination, I have a public duty to perform, to say
nothing of the character I have to sustain amongst you as
a member of this society. I sincerely hope, however, that
those gentlemen will take it all in good part, and believe that
it is only for the reasons above assigned, and not from any

62 Structure of a peculiar Combustible Mineral,

public or private feeling of opposition to their opinions that I
appear before you this night.

I will not dwell long upon the subject, as it must be very
clear to you all—first, that the specimens examined by these
gentlemen must have had more or less of plant structure im-
bedded in them; secondly, that they have evidently mistaken
the peculiar arrangement of the combustible and earthy por-
tions of the mineral for vegetable cellular tissue. Thirdly,
they can certainly never have examined sections of many
coals microscopically, as one and all tell you that they saw
the same structure in the mineral as they did in coals. Had
they made sections of coal in two directions, at right angles
to each other, they could hardly have failed in seeing, almost
at a glance, how much the sections differed in structure the
one from the other. That such is really the case, even in the
coals which they state in their evidence they have examined,
may be shown by reference to Plate IV. In fig. 1 is repre-
sented a transverse section of the so-called brown methil ;
and in fig. 2, a longitudinal section of the same. ‘The two
structures are so different in appearance, that, had such
sections been made, I feel confident there could not have
been a second opinion on the subject. In fig. 3 is shown a
transverse section of the black methil, and im fig. 4 a longi-
tudinal section. ‘The differences, if anything, are even more
striking than in the brown methil. But what will be said
of figs. 5 and 6, which represent a transverse and longitudinal
section of Lesmahagow cannel coal? That anything at all
resembling such a structure as this, can be found in sections
of the mineral in question, except when coal is present, I
emphatically deny.

Now, granting for a moment that the structure of the
mineral be cellular, what plants, I would ask, could the cells
have belonged to? Can any botanist produce a single
instance of a recent or fossil plant of the same thicknesssas a
seam of the Torbanehill mineral, which shall be made up of a
mass of cellular tissue, that is, without vessels or woody fibres
being present with the cells?

Again, if the structure be cellular, we should expect to find
the most durable part of the cell—the cell wall—always pre-
sent, which is not the case. If this view be correct, the yellow
particles being solid must be the contents of colt they cer-
tainly cannot be cells. ‘The cell-wall also, as far as we know
it, in recent and fossil plants, always presents on section a
more or less uniform thickness and a homogeneous appear-
ance; whereas the structure around the yellow particles in all
cases, except where plants are present, is minutely granular,

from the Coal Measures of Torbane-hill. 63

being in reality the clayey or earthy ingredient of the
mineral,

None of the defender’s witnesses, it appears, ever examined
the ash of coal; and one witness in particular, Dr. Redfern,
stated that the examination of ‘ash in general was liable to
great sources of fallacy, and placed no dependence upon it ;’
whereas, it subsequently appeared that he had never examined
the ash of ordinary coal with the microscope.

Were I disposed to be hypercritical, I could mention many
other points in the evidence that I entirely dissent from; but
I trust I have already said enough, and will therefore sum up
my remarks by stating that I consider the mineral in ques-
tion is not a coal, being structurally different from all un-
doubted coals, including those with which it appears it has
been compared by the microscopists engaged by the defender.
In order, therefore, that the scientific world in general may
have an opportunity of judging for themselves whether this
statement be correct or not, I have put specimens of the
mineral and of these coals into the hands of the preparers of
microscopic objects, and in a short time sections will be on
sale by them and by the principal opticians in this metropolis.

I might by some persons be accused of unfairness in
making even these few remarks upon the evidence of the wit-
nesses for the defence, when they are all located in different
parts of Great Britain, and therefore not able to be present
this evening to answer for themselves. I wish, however,
that they could have been here, and more especially if they
could have brought with them the sections upon which their
opinions were formed, and the drawings which were produced
in court. They might say, perhaps, that it would not be fair
play to send their specimens, their drawings, and their remarks
into an enemy’s camp; on my own part, however, | can ven-
ture to state that | am ready to appear before any tribunal of
scientific men in this kingdom, and my drawings and speci-
mens shall be open to all who may be interested in the subject,
to examine for themselves. I beg it may be expressly under-
stood, that should there be any one point in this paper which
on subsequent investigation may turn out to be incorrect, I
shall be as ready to come forward and acknowledge myself in
error as | now am to express an opinion not hastily formed :
my only object, as I said before, is truth ; and by truth I will
abide.

There is one other point that I would briefly allude to
before drawing my remarks to a conclusion, and this is a
portion of the Lord President’s address to the Jury, in which,

64 Structure of a peculiar Combustible Mineral,

as before stated, Mr. Bowerbank and myself are placed in no
very enviable position ; it is as follows :—

“* Besides those gentlemen who were examined as geologists and che-
mists, and who differ so widely, there was examined another class of men,
and possessed of great attainments—lI refer to the microscopists. One of
them was the late President of the Microscopic Society of London—a
learned body, who make it their object to pry into all things. Three of
these gentlemen were examined for the pursuer, and four for the defender.
The pursuer’s witnesses told you that there was no trace of organic struc-
ture, no woody fibre or tissue, in short, no trace of vegetable matter in
this substance, although occasionally there might be the incidental pre-
sence of vegetable remains. The witnesses of this class on the other side
told you, on the contrary, that in every part of it there was the most clear
vestiges of vegetable structure. I do not know, when I have so many
geologists, and so many microscopists telling me that it is not coal, and
so many on the other side telling me the opposite, I say Ido not know
that I feel myself much the wiser, or further advanced in the inquiry.
But if you have, in addition, a great number of chemists, and speaking
with equal authority and equal contrariety, it is difficult to know what to
make of the controversy. Ido not know that I have anything to say
against the skill of the microscopists, or the skill of any of those gentle-
men ; but one general remark may be made on the microscopic testimony, -
and it is, that there are those who see a thing, and also those who do not
see it—those who do see it, cannot see it unless it is there, and those who
cannot see it do not see it at all. But very skilful persons looking for a
thing and not seeing it, creates a strong presumption that it is not there.
But when other persons do find it, it goes far to displace the notion that it
is not there. But there is another observation on the microscopic evidence
that occurred to me. Ido not know whether I am under any misappre-
hension, but I think that three, certainly two, of those examined by the
defenders, are botanists also; and I do not think that any of those exa-
mined for the pursuer, two of them from London, represented themselves
as botanists. Now, the defender’s witnesses are accustomed to look for
plants, and can understand them when they see them. The gentlemen on
the other side again, looking for woody fibre or tissue, are not, as I under-
stand, conversant or skilful in fossil plants. But finding such a difference
of opinion, and such opposite conclusions arrived at by those persons, I do
not know, unless you think that some gave their reasons more satisfac-
torily than others—I say I do not know that I feel my mind much
relieved from the difficulties of this case by listening to all that evidence.
It is very interesting no doubt, and if they were all standing on one side,
and nobody standing on the other side, it might be very satisfactory to
one’s mind to listen to such evidence.”

To such remarks I would briefly reply that, however
severe a counsel may be in his cross-examination, and how-
ever strong his language in addressing the jury may be, I
think it to a certain extent excusable, as he is endeavouring
to do the best for his client; but I must confess my great
surprise that a learned judge should see fit to single out one
set of scientific witnesses from the pursuer’s side, and hold
them up, I would say, almost to ridicule; that he did so on

from the Coal Measures of Torbane-hill. _ 65

the present occasion, the part of the address which I have just
read to you will show. I think it will eventually turn out that
the two members of the Microscopical Society of London,
*‘ that learned body who make it their object to pry into all
things,” are accustomed to look for plants, and can under-
stand them when they see them; nay, I will assert that they
can do more, for they can tell when a particular structure is
not a plant. Had his Lordship been silent on the point, he
would not have laid himself open to these truly justifiable
remarks,

I would now, gentlemen, in conclusion, leave the matter in
your hands. [ think that the subject in question is one of
the most important ever brought before the notice of this
Society, and one which no set of men in this or any other
country are so competent to investigate. Most of the members
of this society are, as stated in the certificate for suspension,
‘‘ attached to scientific pursuits,” and most of them are in
possession of the best instruments, and are accustomed to use
them; let them, therefore, study the subject for themselves,
and give independent testimony. Where, I might ask, can
be found a correct definition of coal? I believe, at present,
no such definition is extant, and it is on this account that I
look upon the trial of Gillespie versus Russel, as one of the
greatest importance to the geologist, the chemist, the mineralo-
gist, and the microscopist ; and | am of opinion that from it
will spring, not only a perfect definition of coal, but of other
combustible substances found in connexion with it, and,
therefore, it is to be hoped that such contradictory statements
as were made by the different scientific witnesses on the trial
in question may in future be avoided. It remains, then, for
the microscope, ‘‘ that most valuable of all scientific instru-
ments (to quote the words of Mr. Ross) ever yet bestowed by
art upon the investigator of nature,” to assist in deciding the
true structure of coal, as it has already done that of many
other organic substances of a previously-doubtful nature.

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Roper, on the Diatomacee of the Thames. _ 67

Some Observations on the Diatomacex of the Thames. B
F.C. S. Rover, F.G.S. (Read January 25th, 1854.)

In the year 1843 M. Ehrenberg, read before the Academy of
Sciences of Berlin a paper on the microscopical marine infu-
soria of the deposits of the Elbe,* in which he established the
remarkable fact that at Gliickstadt, a distance of forty miles,
and even above Hamburg, upwards of eighty miles, from the
mouth of the river, marine siliceous-shelled Infusoria were
found alive, and their skeletons deposited in such abundance
in the mud of the river, that at the former locality they form
one quarter to one-third of the entire mass, and that the pro-
portion is still about half that amount at Hamburg, as far as
the flood-tide extends. All his observations gave a great pre-
dominance of marine over fresh-water species, even when the
salt taste of the water was no longer perceptible.

In the lists which accompany this paper, M. Ehrenberg
enumerates thirty-four marine species, under the style of
siliceous-shelled Polygastrica, the whole of which would now
be classed as Alge@, under the order Diatomacee. The local
distribution of these organisms is a point of some interest ; and
as well-authenticated lists of species from the different localities
in Great Britain have still been only partially attempted, I am
induced to lay before the Society the results of some observa-
tions on the deposits of the river Thames, which accord in a
great degree with those made by Ehrenberg in the Elbe,
though the proportion of marine to fresh-water species is more
equal at corresponding distances from the sea.

The abundance of the Diatomacee, and the facility with
which the different species have been collected at Hull,
Poole Harbour, and other well-known localities, where they
may be gathered alive, and offer such advantages for acquiring
an intimate acquaintance with their habits and modes of
growth, has tended, in a great measure, to divert attention
from those which are deposited by the Thames water; and,
with the exception of some species of Triceratium, Eupo-
discus, and a few other forms, the greater part of the list I
shall hereafter mention has been hitherto, so far as I am
aware, altogether unnoticed, or at all events no special detail
of them has been given Romi that locality.

The chief cause, I imagine, for this neglect of the Diato-
macee of the Thames and other rivers, has arisen from the
fact, that observers have endeavoured to pursue the same plan

* Verhandl. der Konigl. Preuss. Akad. der Wissenschaften zu Berlin,
1848.

VOL. IT. h

68 Roeer, on the Diatomacee of the Thames.

which meets with such success in the localities I have before
alluded to, that is, to examine them in a living state; but, as
far as I can judge from ny own experience, this affords a most
unsatisfactory result ; and after a careful examination of the
mud deposited at different points in the Thames, any one
might easily arrive at the conclusion that the varieties to be
met with were comparatively few, and, except for the exami-
nation of some of the larger species, not worth the time neces-
sary for extended observation.

Having, some months back, brought home a bettleful of
the black mud from the extremity of the Isle of Dogs, taken
about half-way between high and low water mark, and for
several nights successively submitted it to a careful examina-
tion, the only species of Diatomacee I met with were a Trice-
ratium favus, and several specimens of Coscinodiscus radiatus
and Surirella splendida. 1 had laid it aside for some time,
when it occurred to me that the same course of proceeding
which is necessary to bring out the siliceous frustules from
guano might prove equally efficacious with this Thames mud.
Acting on this idea, I boiled a portion of it for some time in
hydrochloric and afterwards in strong nitric acid, until the
whole was perfectly clean: and, on mounting it, the result far
exceeded my expectations ; for though impossible to form
an accurate conclusion, I should imagine that, excluding the
coarse sand, nearly one-fourth of the finer part of the residuum
was entirely composed of the siliceous valves of different
species of Diatomacee ; and the prevalence of marine forms
also proves that, at the distance of nearly forty miles from
the mouth of the Thames, their distribution is very similar
to that previously described by M. Ehrenberg in the Elbe.

The only observations on this point of the inquiry, as
regards British rivers, that I have met with, are notices of the
species which occur in the Humber, and in a paper by Mr. T.
F. Bergin,* read before the Microscopical Society of Dublin
in 1842, who, from a careful examination of the deposits of
the Liffey, after a perusal of Ehrenberg’s paper on the Mud
Banks in the Harbour of Wismar, was led to a different con-
clusion; and stated it as his opinion that a few species of
Navicula, not comprising 1-1000th part of the mass, were the
only organized forms that occurred in the mud deposited by
that river. The cause of this he attributes to the fact of the
source of the river being so short a distance from the sea, and,
having its rise in the mountains of Wicklow, the rapidity

* Microscopic Journal, vol ii., p. 68.

Roprr, on the Diatomacee of the Thames. | 69

of the current is so great, that the germs of these minute
organisms have not time to increase and multiply as they do
in more sluggish streams, flowing for a long distance through
alluvial deposits.

A similar occurrence of marine Diatomacee at a considerable
distance from the sea has, however, been noticed by Professor
Bailey, in America, who, in his ‘ Microscopical Observations
on South Carolina and Georgia,’ published by the Smithsonian
Institution, expresses the surprise with which he found in
Lake Monroe, 200 miles from the mouth of the St. John’s
river, specimens of Amphiprora constricta, Odontella poly-
morpha, and Navicula elongata, which he considered decidedly:
marine, and which had often occurred to him on the shores of
the Atlantic.

I now proceed to give lists of the species from different
localities in the Thames, placing those from the Isle of Dogs
first, and comparing them with the forms from Hammersmith
and near Gravesend ; and though I have been unable at pre-
sent to examine the deposits of the two latter localities so as
to give more than a general view of the species, yet these are
sufficiently well marked to show the distribution of those
peculiar to marine and fresh water.

In all the localities many species of Melosira, Odontidium,
and other genera occur, which, from the want of good figures,
I have been unable to name. The well-marked frustules of
those figured in the first volume of the Rev. William Smith’s
valuable synopsis have been easily recognized, from the ex-
tremely accurate figures there given. In all cases where any
doubt existed, I have referred to slides of the species authen-
ticated by Mr. Smith himself. In some few instances I am
indebted to his kind assistance, and also to his able coadyjutor,
Mr. West, for the determination of forms I was unable
satisfactorily to identify, and in a few others I have depended
on the figures of Kiitzing’s work on the Diatomacee. One if
not two species of Dictyocha occur in the mud from the Isle of
Dogs, but I have excluded them from the list, as there appears
some doubt if they can be correctly referred to the same order.

Marine and Brackish Water Species from the Isle of Dogs.

1. Epithemia sorex 9. Eupodiscus argus

2. se musculus 10. “5 fulvus

3. Amphora affinis li. a radiatus

4, - hyalina Zs ss sculptus

5. Cocconeis scutellum 13. Actinocyclus undulatus
6 N diaphana 14, aa sedenarius ?
7. Coscinodiscus radiatus 15. Triceratium favus

8 A eccentricus Care, ie striolatum ?

h 2

70 Roper, on the Diatomacee of the Thames.

17. Triceratium undulatum
18. alternans
19. Cyclotella Kutzingiana
20. Campylodiscus cribrosus

21. bi-costatus
22. Surirella Brightwellii
23. 5 ovata

24. Fs gemma

25 * fastuosa,

26. a salina

27. Tryblionella marginata
28. 9 punctata
29. an acuminata
30. 5 gracilis
31. Nitzschia sigma

32. - angularis

33. » parvula

34. ig, dubia

35. Amphiprora alata
36. Navicula elliptica
37. MP didyma
38. 3 punctulata

39. Navicula Jennerii

40. bs pusilla

41. - elegans

42. Pinnularia directa

43. Bs distans

44. 5 peregrina
45. Stauroneis pulchella
46. Pleurosigma hippocampus
47. as strigilis
48. Synedra gracilis

49. » erystallina
50. » superba

51. » tabulata

52. Doryphora amphiceros
53. ss Boéckii
54. Odontella aurita

. Podosira Montagnei

. Grammatophora marina
. Zygoceros rhombus

. Melosira nummuloides

. Achnanthes (a spec.)

Fresh-water Species.

. Epithemia turgida

. Amphora ovalis

. Cocconeis placentula
10. Campyllodiscus costatus
11. Surirella biseriata

1

2 - alpestris

3. argus

4, Cymbella Ehrenbergii
D. re maculata

6. 55 cuspidata

7 i‘ helvetica

8

9

12. . pinnata

13. Cymatopleura solea
14. 4 elliptica
15. Nitzschia sigmoidea
16. Bs linearis

17. Navicula ovalis

18. a: producta

Sys nA rhyncocephala
20. 55 inflata

21. “ gibberula

22. amphisboena

23. Pinnularia acuta

24, Pinnularia viridis

25. e oblonga

26. 9 major

27. “a radiosa

28. Stauroneis linearis

29. ”» Pheenicenteron
30. io anceps

31. Pleurosigma attenuatum

. Synedra radians
. Cocconema lanceolatum

a parvum
‘ts cistula
. Gomphonema acuminatum
a capitatum
9 curvatum
3 constrictum
a cristatum
dichotomum

. Odontidium hyemale
. Fragillaria capucina
_ Tabellaria ventricosa
. Diatoma vulgare

From this list it appears that out of one hundred and four
species, fifty-nine are peculiar to marine and brackish water,

of which thirty are decidedly marine.

The following six

species are, however, all that are identical with those included
in M. Ehrenberg’s lists from Gliicksiadt and Hamburg, viz. :
Coscinodiscus radiatus and eccentricus, Triceratium favus,
Surirella gemma, Eupodiscus argus, identical with Tripodiscus

Roperr, on the Diatomacee of the Thames. 71
germanicus and Actinocyclus undulatus, probably identical with
Actinoptychus senarius. This would seem to show that though
the general results were similar, yet from some peculiarity,
either in the water or the distribution of these minute
organisms, the species abounding in the rivers of the north of
Europe are marked with a distinctive character from those
found in the Thames. The prevailing form in the Elbe ap-
pears to be the Actinocyclus, and its allied genus Actinoptychus
of Ehrenberg, of which he enumerates no less than fourteen

species out of the thirty-four marine forms that he recognised.
On comparing with the foregoing list from the Isle of Dogs,
the species which occur in the mud at Hammersmith and near
Gravesend, it appears, that though a few marine forms are
still found at the former locality, yet the preponderance of
fresh-water species is very great ; whilst at the latter the marine
and brackish water species, with a few exceptions, alone
occur.

The following lists include all I have at present met with
from those localities :—

Marine and Brackish Water Species from the Thames near Gravesend.

1. Epithemia musculus | 21. Nitzschia angularis

2. Cocconeis scutellum | 22. Amphiprora alata

3. Coscinodiscus eccentricus 23, Navicula Jennerii

4, — radiatus 24, Py didyma

5. marginatus ? 25 5 punctulata

6. Eupodiscus areus 26. Pinnularia cyprinus

ce 5 crassus 27. Stauroneis salina

8. Actinocyclus undulatus 28, Pleurosigma angulatum
u. a sedenarius ? 29. a hippocampus
10. Triceratium favus 30. Balticum
LW 45 alternans 31, Doryphora amphiceros
12. Campylodiscus cribrosus 32. Achnanthes brevipes
13. Surirella ovata ood. Grammatophora marina
14, i gemma 34, Podosira Montagnei
Ld. # fastuosa 35. Melosira nummuloides
16. Tryblionella acuminata 36. as sulcata
17. ne marginata 37. eA salina,
US; As punctata 38. Odontella aurita
19. Nitzschia sigma 39. Orthosira marina
20. i dubia

Fresh-water Species from Gravesend.

1. Cocconeis placentula 5. Navicula minutula

2. Coseinodiscus minor 6. Synedra ulna

3. Nitzschia sigmoidea ‘7. Cocconema cistula

4, Navicula cuspidata 8. Cyclotella rotula

Marine and Brackish Water Species from the Thames near Hammersmith,

1. Amphora membranacea
2. Coscinodiscus eccentricus
3. Actinocyclus undulatus

4,

eo

Surirella Brightwellii
Tryblionella gracilis
a acuminata

72 Roper, on the Diatomacee of the Thames.

7. Nitzschia sigma 11. Pleurosigma hippocampus
8. Nitzschia parvula 12. Doryphora amphiceros
9. Navicula elliptica 13. Gomphonema marinum
10. Pinnularia directa 14. Odontella aurita
Fresh-water Species from the same Place.
1. Epithemia turgida 16. Pinnularia viridula
2. Cymbella Ehrenbergii 17. He stauroneiformis
o. Amphora ovalis 18. Pleurosigma attenuatum
4. Cocconeis placentula 19. Synedra ulna
5. Campylodiscus costatus 20. Cocconema cymbiforme
6. Surirella biseriata 21. ip cistula
7. Cymatopleura solea 22. Gomphonema acuminatum
8. 5 elliptica 23. - constrictum
9. i apiculata 24. Fragillaria virescens
10. Nitzschia sigmoidea 25. Diatoma vulgare
11. Navicula amphisbeena 26. Melosira arenaria
Alas ms crassinervia 27. y varians
13. fe inflata 28. Fragilaria capucina
14, ‘5 cuspidata 29. Coscinodiscus minor
15. x amphirhynehus

From these lists it appears that at Gravesend, out of forty-
seven species, eight only are decidedly peculiar to fresh water ;
whilst at Hammersmith we find there are twenty-nine fresh-
water species out of a total of forty-three ; showing, however,
that the influence of the flood-tide, even at that distance from
the sea, gives a decided character to the Diatomacee deposited
by the water. The following ten species are all that are
common to the three localities :— Coscinodiscus eccentricus,
Actinocyclus undulatus, Tryblionella acuminata, Nitzschia sigma,
Pleurosigma hippocampus, Doryphora amphiceros, Odontella
aurtta, Cocconets placentula, Nitzschia sigmoidea, and Cocconema
cistula, of which the three latter alone are peculiar to fresh
water. These are all forms which more extended observation
on the deposits of other river and estuary deposits will pro-
bably prove to be most universal in their distribution. I have
found most of them in the mud of the Avon from Bristol, and
also in that deposited at Pembroke Harbour; but it will re-
quire a careful examination of many other deposits to prove
that any have a purely local habitat, or are entirely confined
to sea or fresh water.

The following species which occur in the Thames have also
been found by Professor Bailey in America, recorded in ‘Sil-
liman’s Journal of Sciences’ for 1845, vo]. xlviii. p. 837 :—

Iu the Mud from Charleston Harbour.

Actinocyclus senarius Rhaphoneis amphiceros
Coscinodiscus eccentricus Ne rhombus
Eupodiscus argus Triceratium favus

Pinnularia didyma | Zygoceros rhombus
Pleurosigma Balticum

Roper, on the Diatomacee of the Thames. 73

And in the Mud from Newhaven Harbour.

Actinocyclus senarius Pinnularia peregrina
Coscinodiscus eccentricus - didyma
Gallionella sulcata Rhaphoneis rhombus
Grammatophora marina |

A proof of the widely-extended distribution of these species.

From the first of the foregoing lists I have selected a few
species for more particular notice, and annex drawings of the
most interesting, on the scale adopted by Mr. Smith, namely,
400 diameters.

There is:a large species of Cocconeis (Pl. VI. fig. 1), elliptical
in form, and marked longitudinally with undulating striz, and
also with faint transverse lines, concentric with the extremities
of the valve, but only visible with a high power and oblique
light. The perfectly elliptic form and peculiarity of the cross
strie seem to distinguish it:from the C. placentula of Mr.
Smith ; but I am doubtful whether it may not be a variety of
that species,

Of the four species of EHupodiscus, the most plentiful is
EF. radiatus, which, from one specimen, in which three frustules
were conjoined, may probably sometimes occur concatenated,
in a similar way to Odontella aurita. EE. sculptus, the most
peculiar in its markings, is rarely met with; and L. fulvus
and argus are sparingly distributed. The latter shows the
delicate hexagonal reticulations alluded to by Professor Quekett
as marking the Tripodiscus Rogersii of Professor Bailey. ‘The
star-shaped cells appear, when seen by direct light, to be
placed in the centre of small bosses or protuberances, in which
it differs from all other Diatomacee that I am acquainted with.

The Actinocyclus undulatus of Mr. Smith’s Synopsis occurs
abundantly. This species appears to include the Acti-
noptychus senarius of Ehrenberg and Kiitzing ; but after a
careful examination of many specimens, I have been unable
to make out any undulations similar to those of fig. 4, in
Plate V. of the Synopsis, in the large species that occur in the
Thames and elsewhere; and although a multiplication of
species is a point carefully to be avoided without good
grounds, it appears to me that the appellation undulatus
should be confined to a small form, in which these undula-
tions distinctly occur, and the large and well-known species
retain the name originally applied to it by M. Ehrenberg,
namely, A. senarius.

Sparingly distributed, I have another large and beautiful
disc (fig. 2), with sixteen septa, the surface of which is covered
with faint cross-stria, similar to those of Pleurosigma ; and in

* See Histological Catalogue, p. 212.

74 Roper, on the Diatomacee of the Thames.

that respect it resembles the valves from Natal, for which
. Mr. Shadbolt proposed the name of Actinophenia ; but I find
this striation is no distinctive character, as all the specimens
of A. undulatus (or senarius) that 1 have examined have the
same peculiarity, and the septa are plainly discernible, espe-
cially with the parabolic condenser. In the lists I have ap-
plied to it provisionally the name of Actinocyclus sedenarius,
as it approaches very nearly to Ehrenberg’s figure of that
species in the ‘ Berlin Transactions’ for 1839, tab. 4, p. 2.
The septa appear to have their origin from the smooth central
portion or pseudo-nodule, and to terminate at slight eleva-
tions or openings at the margin of the disc, and in perfect
specimens those on one valve are opposite to the interspaces
on the other. The front view exhibits slight traces of undu-
lations, as in fig. 13, not in continuous waved lines, but rising
to points at the extremities of the rays, giving the side view
an appearance similar to that of a ridge-and-furrow roof. The
diameter varies from 1-288th to 1-187th of an inch.

Of the genus Triceratium four species occur. A small one,
by no means uncommon, is represented by fig. 3, which
I consider the J. striolatum of Ehrenberg; it has convex
sides, small horn-like processes at the angles, which are rather
obtuse, and is marked with minute dots or cells, radiating
from the centre. In the determination of this species I am,
after a careful examination, compelled to differ from Mr.
Brightwell, who, in his monograph of this genus in a late
Number of the ‘ Microscopical Journal,’ refers to a Paper by
M. Ehrenberg in the ‘ Berlin Transactions’ for 1839, in which
there is a figure of 7. striolatum, and the following description
of the species: —“ Testule lateribus triquetris convexis, angulis
sub-acutis, superficie subtilissime punctato-lineata, dorsi cin-
gulo medio levi; and yet Mr. Brightwell describes it as
with ‘concave ends,” and figures it with concave sides; and
in the frustules I have seen of his species, the central band on
the front view is punctate or cellular, whereas it is described
by Ehrenberg as smooth. ‘The cellular structure of the side
view is also so plainly apparent, that it would hardly have
been described as ‘ subtilissime punctato-lineata ” by so careful
an observer. Looking, therefore, at Ehrenberg’s figure and
description, I should conclude that the species figured by
Mr. Brightwell cannot be the JT. striolatum, but should re-
ceive some other appellation. The concave sides would seem
to refer it to T. pileus of Ehrenberg; but I have not seen a
figure or full description of that species.

Triceratium alternans of Bailey is rarely met with; and I
have only one specimen of JT. undulatum, in which the peculiar

Roper, on the Diatomacee of the Thames. 75

projection of the posterior valve beyond the undulating sides
of the upper, as noticed by Mr. Brightwell in his Paper before
alluded to, is plainly shown. |

Campylodiscus costatus and cribrosus are frequently met
with. Another small species is represented by fig. 4, which
Mr. Smith informs me he has named 67-costatus, and that he
will give a figure of it in the addenda to his second volume.
In appearance it so much resembles C. clypeus, that 1 had
applied that name to it, especially as that species is included
in Ehrenberg’s lists as occurring at Gliickstadt, Hamburg, and
some localities in Holland, and was found by Professor Bailey
in Lake Monroe. The valve is nearly circular, saddle-shaped,
canaliculi about forty, distinct, length at the sides about half
the radius, at the ends much shorter. The central portion
has two narrow bands of coste parallel with the terminations
of the side canaliculi. Diameter is about 1-384th of an
inch,

The most abundant species in all the slides | have examined
is represented by figs. 7 to 10, which I believe would all
be included as varieties of Doryphora amphiceros by Mr.
Smith, and as different species of Rhaphoneis by Ehrenberg
and Kiitzing. ‘The difference of form is so great, and the
peculiarity of the cellular markings so apparent, that they
appear to furnish data for specific distinction quite as good
as are afforded in many species of Navicula and Plewrosigma.
Not having Ehrenberg’s figures or descriptions to refer to,
I am guided solely by the “species Algarum” of Professor
Kiitzing. Fig. 7, from its lanceolate form, strong granular
markings, and well-marked median line, might probably be
referred to Rhaphoneis gemmifera. The length varies from
1-319th to 1-3820th of an inch; breadth, about 1-1090th of an
inch; it occurs but sparingly. Fig. 8 is rarely met with, but
is readily distinguished by its more robust form, the greater
delicacy of its striz, and the slightly marked and nearly
parallel sides of its median line. The length is 1-349th of
an inch, and breadth 1-779th of an inch. It would be referred
to Rhaphoneis fasciolata. Fig. 9 is exceedingly common, and
in the size of its markings resembles fig. 7, but differs in
being more concentric, and nearly obliterating the median
line at the acute extremities of the valve. The breadth of
the valve is also much greater in proportion to the length.
~The length is 1-600th of an inch, and breadth 1-1224th of
an inch. It agrees with Rhaphoneis pretiosa. Fig. 10 is
widely different from any of the preceding, and is by no
means abundant. ‘The valves are very diaphanous, the mark-
ings faint, median line obscure, and form ‘sub-orbicular, the

76 Rorer, on the Diatomacee of the Thames.

apices being very short; the length is 1-588th to 1-779th of
an inch, and breadth 1-1034th to 1-968th of an inch. I
should refer it to Rhaphoneis rhombus. The only point of
distinction between this genus and the Doryphora of Pro-
fessor Kiitzing appears to be the presence of a stipes; and it
would be a point of some interest to determine whether
these forms are attached in a similar manner, or whether, as
I imagine from the abundance with which they occur, and the
absence of any direct negative observations, the frustules are
free as in Navicula.

A large and well-marked species is represented by fig. 5,
which has not, I believe, been hitherto figured as British. I
have been unable to obtain a front view of a perfect frustule,
though the single valves are by no means uncommon. By a
comparison with some specimens of Zygoceros rhombus from
Petersburg, Virginia, kindly lent me by Professor Quekett,
I have little doubt that it can safely be referred to that
species,* as the only difference is, that in the Thames spe-
cimens, the side view of the valves is rather broader in
proportion to the length. The valves are nearly rhomboidal,
slightly produced at the extremities, and terminate in a pro-
jecting tubular horn or spine. The surface is minutely
punctate with small hexagonal cells, radiating from the
centre, and has from three to six small spinous processes at
the sides, with two rather longer at the extremities of the
valve... The length varies from 1-300th to 1-188rd of an inch,
and breadth from 1-375th to 1-260th of an inch.

Figs. 11 and 12 are, I believe, front and side views sie
Zygoceros surirella of Ehrenberg. I have only met with one
specimen of the perfect frustules, represented by fig. 14, which
agrees in form with the figure given by him in the ‘ Berlin
Transactions’ for 1839, tab. 4, fig. 12, and shows the smooth
central band and striations, which distinguish the side view.
Fig. 16, which I consider the side view of a larger specimen,
somewhat resembles the genus Ahaphoneis, but differs, in
the markings being nearly parallel, and though granular, so
confluent as almost to appear as lines; the central smooth
portion terminates in two lobes, corresponding with the pro-
jections, which appear at the extremities when the front view —
is obtained. ‘The length is 1-714th to 1-1240th of an inch,
and breadth 1-1500th to 1-2500th of an inch. I have met
with the same species in the deposits of Pembroke Harbour.

Fig. 6 a and b represents a small cross-shaped valve that
occurs sparingly, which Mr. Smith, from a drawing, thought

* The genus Zygoceros is included by Mr. Smith in that of Biddulphia ;
this will, therefore, be the Biddulphia rhombus of the ‘Synopsis.’

Roper, on the Diatomacee of the Thames. — At

might be referred to his Odontidium tabellaria: it is peculiar,
from the strongly-marked cross stri@, which occur on each side
of the valve; the length is 1-1385th and the breadth 1-1750th
of an inch. The form of the valve is similar to Ehrenberg’s
figure of Staurosira construens,* which he describes ‘‘as a
four-angled Fragilaria, separated from the nearly allied genus
of Amphitetras, by the absence of openings at the four angles,+
but without authentic specimens for comparison, it is im-
possible, from the small outline figure he gives, to refer it
with certainty to this genus. Mr. West informs me he has
met with it from many other localities.{| From the Thames
near Gravesend [ have lately obtained a large and fine spe-
cimen of Coscinodiscus, about the 1-107th of an inch in
diameter. It has a smooth spot in the centre of the valve, and
with that exception is covered with hexagonal cells, radiating
towards the circumference. Mr. Smith informs me it is quite
new to him, but approaches somewhat to C. marginatus, but
differs from the descriptions given of that species. I have at
present no other forms, either from this locality or at Hammer-
smith, that call for special notice.

From the foregoing observations it appears that at ee
distance of at least fifty miles from the sea, the deposits of
the Thames are still, to a certain extent, influenced by marine
forms of life, and that at Greenwich, which is about forty
miles from the mouth of the river, a most distinct marine
character is shown by the examination of the species of
Diatomacee which occur there. I think it very probable
that many species are only brought up by the flood-tide, and
being unable to exist in the slightly-brackish water, the
siliceous skeletons are merely deposited in those parts of the
river least subject to disturbing causes, and that they would
rarely be met with in a living state. That they have a per-
ceptible influence on the formation of shoals and mud-banks
in the bed of the river there can be no doubt; and the great
abundance and general distribution of species serve to illus-
trate the occurrence of similar deposits in a fossil state, at
localities now far removed, by alterations in the earth’s surface,
from the streams or harbours in which they were originally
deposited.

Another point, probably worthy of attention, is the in-
fluence these organisms have in the formation of deltas at the

* See Berlin Academy Transactions, 1847, tab. 1, fig. 44.

t See Berlin Academy Proceedings, 1843, p . 45.

{ From specimens I have lately seen of Ae Harrison, W.S.,
I am inclined to believe that this may be a small form of that species

rather than O. tabellaria. As it is a doubtful form I have not included it
in the lists.

78 Roper, on the Diatomacee of the Thames.

mouths of large and slowly-flowing rivers, such, for instance,
as the Mississippi, in which the mean velocity of the current
at New Orleans is only about one mile and a half per hour
for the whole body of water. Sir Charles Lyell, from expe-
riments on the proportion of sediment carried down by the
river, has calculated that, taking the area of the delta at 13,600
square miles, and the quantity of solid matter brought down
annually at 3,702,758,400 cubic feet, it must have taken 67,000
years for the formation of the whole.* Now, as the siliceous
frustules of the Diatomacee are secreted from the water alone,
and would most probably be extremely abundant in so
sluggish a stream (especially as Professor Bailey has found
both marine and fresh-water species abundant in the rice-
grounds), there can be little doubt that, without taking the
larger proportion noticed by Ehrenberg in the Elbe, even if it
were considerably less, it would reduce the above period by
several thousand years, and the same cause would probably
apply with equal force to the Ganges and Nile. M. Ehren-
berg considered that at Pillau there are annually deposited
from the water from 7,200 to 14,000 cubic metres of fine
microscopic organisms, which in the course of a century
would give a deposit of from 720,000 to 1,400,000 cubic
metres of infusory rock or Tripoli stone.

My principal object in the foregoing paper has been to
direct the attention of microscopists more particularly to the
Diatomacee deposited by rivers and in tidal harbours, not only
in those localities where they occur in overwhelming abun-
dance, on the surface of quiet estuary waters, but in the mud
itself, in which many of the rarer forms, and doubtless many
new species, are yet to be found. That such an examination
is still a desideratum is, I think, shown by the fact that out of
the 279 species described by Mr. Smith in the first volume of
his ‘Synopsis,’ only six are given as inhabitants of the
Thames, and a very limited number to the Avon, Orwell, and
some other rivers; whilst the Severn, the Mersey, and many
of our tidal harbours are altogether unnoticed.

That examinations of this nature may sometimes prove
useful in an economical point of view is very probable, parti-
cularly as it has been noticed that the best samples of guano
contain the greatest number of these siliceous skeletons, which
doubtless serve to replace the large amount of silica ab-
stracted from the soil by the cereal crops. Hence it is pro-
bable that the deposits of many of our rivers would have a
beneficial effect if applied to the land, and it rests with the
microscopist to point out the most favourable localities for

* Lyell’s Principles of Geology, 8th edit., p. 219.

Roper, on the Diatomacee of the Thames. — fat

obtaining it. Ehrenberg notices an instance where this has
been done in Jeverland, where a blue sand, abounding in cal-
careous and siliceous shells, is collected, and greatly increases
the fertility of the arable soil to which it.is applied; and
Professor Bailey also states that the mud of Newhaven har-
bour is used as a fertilizer, and is found to contain 58°63
per cent. of silica.

The distribution of the lower forms of Alge, particularly
the Diatomacee, is probably more extended, both in point of
time and geographical range, than any other class of or-
ganized beings. Thus we see associated with gigantic reptiles
and other extinct forms, several existing species of Diatomacee
occurring in the chalk formation before the deposition of the
tertiary strata, proving that the Eocene group is not strictly
entitled to that designation, but that the dawn of the world in
which we live extends much further back in the history of our
planet.* And with respect to their local distribution, Dr.
Hooker, in alluding to the deposits of the Victoria Bar-
rier in the Atlantic Ocean, remarks,+ “‘There is probably no
latitude between Spitzbergen and Victoria Land where some
of the species of other countries do not exist. Iceland, Britain,
the Mediterranean Sea, North and South America, all possess
antarctic Diatomacee. ‘The siliceous coats of species only
known living in the waters of the South Polar Ocean have
during past ages contributed to the formation of rocks, and
thus they outlive several successive generations of organized
beings. The Phonolite stones of the Rhine, and the Tripoli
stone, contain species identical with what are now contri-
buting to form a sedimentary deposit (and perhaps at a future
period, of rock), extending in one continuous stratuin for 400
miles.” |

With the distribution of these forms in our own country
we are only at present partially acquainted, and the prepara-
tion, therefore, of carefully-compiled lists of species from
different localities is still a point to be desired, and might
probably lead to some interesting generalizations.

In conclusion, I have only to hope that this slight attempt
to bring before the Society the results of a careful examination
of the Thames deposits may induce other and more expe-
rienced observers to take up the same subject in other locali-
ties. The facts I have brought forward are sufficient to
afford, in the words of an excellent observer and late member
of this Society, “‘a striking proof of the important part which

* Humboldt’s Cosmos, p. 265.
t Dr. Hooker, Flora Antarctica, vol. ii., p. 505.
{ Mr. Edwin J. Quekett, in London Physiol. Journ, Feb. 1844, p. 145.

—

80 Roper, on the Diatomacee of the Thames.

these minute organisms were created to perform in the depo-
sition of materials for the earth’s surface, and stamp upon
reflecting minds that no creature, even the most minute, is
formed without special purposes ; and that the least in size of
all, by the organization given to them by the great Architect
of the Universe, have been employed to carry out his un-
fathomable intentions.”

wl POm P

OF

THE FOURTEENTH ANNUAL MEETING

OF THE

MICROSCOPICAL SOCIETY.

Tue Microscopical Society of London held their Fourteenth
Annual Meeting, February 15th, 1854,—Grorce Jackson,
Esq , President, in the Chair. The Assistant Secretary read
the following Reports :—

Report of Council.— According to annual custom, the Council
have to make a Report on the state and progress of the Society
during the past year.

The number of members at the last anniversary was—ordi-
nary members 198, associates and honorary 5, giving a total
of 203. Since that time there have been elected 28, making
the total number 231. This number must, however, be re-
duced by 3, who have retired, making a final total of 228,
and being an increase of 25 upon the number at the last
anniversary. ;

The cabinet of objects and the library have been increased
by various donations ; and there are also in the possession of
the Society various drawings and diagrams relating chiefly to
papers read at the meetings of the Society, together with
copies of the several parts of the Transactions and of the
Journal.

The Council have also to state that, in consequence of the
great inconvenience of the present rooms, they have decided
upon removing from them. The Society will return to the
rooms of the Horticultural Society in Regent-street, if possible,
by the meeting on the 29th March.

VOL. I. D

Fourteenth Report of

84

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‘SUOLIGAV THE 40 LHOdda

the Microscopical Society. | 85

The President delivered the following Address :—

GENTLEMEN,—I have much pleasure in again congratu-
lating you on the state of our finances; for, although the
balance in hand is only twelve pounds more than that of last
year, yet we have been enabled to pursue our usual course of
investing the compositions received from life-members, and
have thus increased our funded property from 2102. 5s. 11d.
to 2591. 4s. 1d. It is the opinion of some who have had ex-
perience in these matters, that a society which judiciously
expends its yearly income is in a more healthy condition than
one which hoards a large portion of it, and that therefore we
ought carefully to avoid becoming rich. Until, however, our
dividends form a much larger proportion of our annual assets
than they do at present, we need entertain no fears on this
head ; while the possession of a reserve fund to fall back upon
in case of need cannot be regarded as an evil.

By the arrangement which has been made with the editors
for the supply of the ‘ Microscopical Journal ’ gratuitously to
all our members, and by the prompt publication of our trans-
actions, which have been brought down to the end of the year,
a steady increase both of members and papers may be reason-
ably expected; of which I trust the experience of the past
year is but the commencement. Twenty-eight new members
have been elected, and twelve papers, many of them of con-
siderable interest, have been read.

That of Professor Wheatstone, on the application of bino-
cular vision to the microscope, has pointed out the advantages
we may expect to derive from this principle, when certain
optical difficulties have been overcome; and Mr. Wenham,
by his ingenious contrivances and admirable workmanship,
has vanquished some of these difficulties, and given us a
glimpse of the benefits in store for us.

The modification of artificial light by the intervention of
coloured glasses has often been attempted, but it has generally
been found to impair definition. The combination proposed
by Mr. Rainey, for the purpose of stopping the heating rays,
although it sensibly diminishes the light, appears to answer
remarkably well.

Dr. W. Gregory, Mr. Shadbolt, and Mr. Roper have con-
tributed papers on Diatomacee. The latter, on those of the
Thames, is particularly interesting, as opening a field of
research in our own vicinity, the specimens being obtained
from localities with which we are all acquainted.

Mr. Legg’s paper on sponge-sand contains many hints

86 _ Fourteenth Report of

which collectors and mounters of objects will find useful in
their pursuits. Mr. Boswell has communicated an interesting
fact on the mode of progression of Actinophrys Sol. His
subsequent paper on the bird’s-head processes in Polyzoa had
been anticipated by the accurate and more extended observa-
tions of Mr. Busk, read two months before. The valuable
paper of Professor Quekett, on “‘ a combustible mineral from
the coal measures of Torbane Hill,’ clearly demonstrates the
presence, not merely of the remains of plants, but of a peculiar
woody structure in every description of coal, and the absence
of this peculiar structure in the mineral in question.

In microscopic botany we have been favoured with two
interesting communications: one by Dr. Hobson, on the
development of tubular structure ; and the other on the disease
affecting the vine, by Mr. T. West.

As mostoof shese papers have been already published, a
more extended analysis of them would only be tedious. I
would rather occupy a few minutes in considering how far this
Society, during the fourteen years of its existence, has accom-
plished the objects which its founders had in view at its
formation.

On turning back to our “ History, Constitution, and Laws,”
we find it recorded that one of these objects was the ‘¢ promo-
tion of improvements in the optical and mechanical construc-
tion of the microscope.’ With the improvements which
have been made in the construction of object-glasses, the
Society for many years had but little to do; although, by
promoting the use of the instrument, and by keeping alive a
spirit of rivalry between the different makers, it was not
altogether without influence. Recently, however, an amateur
among our own members has demonstrated the possibility of
getting good definition with an angular aperture that admits
of no appreciable increase; and has thrown out suggestions,
which, if carried into effect, will be productive of still further
advantages.

In the mechanical construction of the instrument, and in
the different methods of illumination, so many improvements
have been made by our members, that [ should take up too
much of your time were I to attempt to enumerate them.

The next object proposed for the Society, “ the communi-
cation and discussion of observations and discoveries,” has
constituted the principal occupation of our hours of meeting;
and for the interest and variety of the subjects, I need only
refer to the volumes of our ‘ ‘Transactions.’

These observations have been altogether the result of indi-
vidual and self-directed researches ; but it is worthy of con-

the Microscopical Society. | 87

sideration whether more might not have been done had we
adopted the co-operative and systematic mode of proceeding
recommended by our first President. ‘That Professor Owen’s
suggestions may not altogether be lost sight of, I will, with
your permission, quote a paragraph or two from his Address at
our Second Anniversary !

After remarking on the importance of conceiving clearly
the aim of our researches, and giving a right direction to our
exertions, he says: “ A slight glance even at the classes of
natural objects, of which the intimate structure remains but
partially, if at all, known, will suffice to show us how many
are the subjects that might be profitably selected by an indi-
vidual or a committee for a systematic series of microscopical
observations. In the animal kingdom, for example, how little
we know of the modifications of the microscopical structure of
shells recent and fossil, of the stony habitations of the nume-
rous class of polypes, of the crustaceous coverings of the
annulose animals, of the calcareous coverings of the Echino-
dermata, or of the bones in different classes of animals, and in
different parts of the skeleton of the same animal !

“‘In Mineralogy how much remains to be done in the
microscopical investigation of different classes of rocks, as of
oblites, of sands, flints, &c.

‘If committees were appointed to take different subjects
of minute research under their respective care, in how short
a time might a vast body of microscopical facts be accu-
mulated !”

Selecting a few subjects from the Professor’s list, let us see
what the systematic researches of three individuals, quite dis-
tinctly carried on, have effected. The structure of shells has
been ably investigated both by Dr. Carpenter and by Mr.
Bowerbank ; the structrue of flints and agates also by the
latter ; and that of bones, developing general views of much
importance, by our indefatigable Secretary.

Had committees been appointed, as Professor Owen sug-
gested, and had their members worked with half the zeal and
-assiduity displayed by these three gentlemen, what a vast
body of microscopical facts might by this time have been
accumulated !

The “ formation of an arranged collection of microscopical
objects” was another of the ends proposed to be effected by
the Society; but, considering the number of our Members,
and that many of them are dextrous manipulators, frequently
engaged in mounting specimens, the progress made in
stocking our cabinet is by no means a subject of congratula-
tion. The last object proposed to be attained was “ the esta-

88 Fourteenth Report of

blishment of a library of standard microscopical books.”
Here also, although something has been done, we have no
cause for boasting. But if every Member who wishes to
refer to such works, and cannot find what he wants in our
library, were to address a note to the Council, giving the title
of the book needed, we should gradually have these deficien-
cies supplied.

There are one or two subjects of microscopical investigation
that do not appear to have attracted our attention so much as
might be wished.

Some communications from the Rey. J. B. Reade, in the
early days of the Society, served to show that the microscope
might be made of great utility in delicate chemical re-
searches; and a paper by Dr. Bird Herapath, in the Fifth
Number of the ‘ Microscopical Journal,’ strongly confirms
this view ; but, with the exception of some incidental notices
of the application of chemical tests to determine the nature
of organic structure, very little of chemical microscopy has
come before this Society. For this there may be a sufficient
reason; the subject is a special one, and chemists may
prefer bringing their microscopical observations before the
Chemical Society, to the alternative of submitting chemical
matters to the Microscopical. How far they are right I will
not determine.

When we look over the list of our Members, and observe
the number of medical men included in it, we may well be
surprised that our ‘Transactions’ have been enriched with so
few papers on Animal Pathology. Had this been the case
only since the institution of the Pathological Society, a reason
similar to that above assigned might account for it; but even
now it may fairly be questioned whether the accuracy of dis-
coveries in microscopical pathology would not be better
tested by a body of men accustomed to use the instrument,
and to examine matters of all kinds with it, than by those
who have not had these advantages, however well they may
be acquainted with the general subject.

A physician in a neighbouring country some years ago
announced that, by the aid of- the microscope, he had disco-
vered a pathognomonic symptom of pulmonary consumption
in a peculiar egg-shaped body occurring in the sputa. It
was afterwards found that in the hospital to which he was
attached the consumptive patients breakfasted on arrow-root,
and the peculiar bodies were some of the unbroken starch
granules that had stuck to their mouths.

In both the addresses of Professor Bell this want of papers
on Animal Pathology is noticed ; and his ideas are so just, and

the Microscopical Socrety. | 89

his language so clear and forcible, that 1 cannot better con-
clude the subject than by quoting the last paragraph from
his Address at our Sixth Anniversary: ‘Let us remember,”
said he, “ that the instrument which we employ is capable of
elucidating subjects of far more importance than the distinc-
tion of species of animalcules, and the demonstration of the
structure of a zoophyte. The relief of suffering, and the sal-
vation of life itself, are amongst the legitimate objects of
microscopic research. Let not our medical members, then,
be satisfied with the mere amusement, or even the bare scien-
tific information to be derived from it; but let them employ
it as an important means of carrying out the great objects of
their profession, in determining the nature of diseased struc-
tures, the distinctions between the healthy and morbid states
of the tissues, and, consequently, in enlarging our means of
restoring health to the sick, ease to the suffering, and life to
the dying.”

It only remains, Gentlemen, for me to express the satisfac-
tion which I feel in resigning this Chair to one whose inti-
mate knowledge of physiology in both its branches, no less
than his general scientific attainments, so eminently qualify
him to preside at our meetings.

It was unanimously resolved—That the Reports of the
Council and Auditors be received ; and that the Reports, with
the President's Address, be printed.

The election of officers took place ; when the following were
declared elected :—

Officers.
MESUUCHE ss Dr. CarrENTER.
PCUSUPCT ek N. B. Warp, Esq.
RGEC ks JOHN QUEKETT, Esq.

New Members of Council.

Dr. Lions, BEALE.

JosH. Gratton, Esq.

M. MarswHa tt, Esq.

Sami. C. WHITBREAD, Esq.

In the place of

WarreEN De La Rug, Esq.
W. Giiert, Esq.

Joun Ler, Esq., LL.D.
Rosert Warineron, Esq.

Hoae, on the Water-Snail. oT

Observations on the DevELopmMENT and GrowtH of the WaTER-
Swart (Limneus stagnalis). By Jasez Hoee, M.R.CS.. &e.

(Read March 29th, 1854.)

In submitting the observations which I have the honour of
bringing to the notice of the Fellows of the Microscopical
Society this evening—on the Development. and Growth of
the Water-snail (Limneus stagnalis)—I do so with considerable
diffidence. When I first gave the subject my special atten-
tion, and began to jot down the remarks that occurred to
me as growing out of my experiences, I was not fully aware
of the extent to which many able investigators had traversed
the same ground before me. So far back as 1754, precisely
a century since, Baker, in his book entitled, ‘ Employment
for the Microscope’ (p. 325), was the parliestito sdeserihe
‘a small water-snail and its spawn, or eggs, fastened in little
masses, against the sides of the glass,” in which he kept
them. It also engaged the attention of the illustrious
Swammerdam; and, more recently, that of Reaumur and
Dr. Grant. Mr. Bowerbank’s very interesting and careful
observations on the ‘ Structure of the Shells of Mollusca and
Conchifera,’ and the scientific researches of Dr. Carpenter,
have thrown great additional light upon this subject. A brief
record of my own personal investigations, with regard to this
department of microscopic observation can, therefore, present
no signal feature of interest beyond that of confirming and
enforcing the experience of the talented and eminent micro-
scopists who have preceded me. It is with this view that I
venture to lay before the Microscopical Society the few
remarks which I have now the privilege of reading, happy if
I shall have contributed, in however slight a degree, to add in
any way to the store of knowledge already accumulated.

Into a glass vase, where my stock of Chara, Vallisneria, &c.,
is growing, | introduced last Autumn a single Limneus, for
the purpose of observing its habits; I was then more espe-
cially curious to see its mode of creeping along, under the
surface of the water, by means of its fleshy foot. Upon one
occasion, as I sat watching the movements of the animal,
attached as it then was to the side of the vase, near the surface
of the water, it suddenly became uneasy, moving to and fro,
and im a short time it began to deposit very slowly, through
a fissure near its ventral aperture, a small gelatinous sac,
filled with transparent specks, at the same time firmly gluing
it to the glass. This sac I examined with a pocket magnify-
ing-glass, and found it contained fifty-six ova. Each egg was

VOL. II.

OZ Hoge, on the Water-Snail.

of an ovoid form, and consisted of a pellucid membrane filled
with a transparent fluid, having a very minute yellow spot, the
yolk, adhering to one side of the cell-wall. Seen with the
sunlight falling upon it, it had all the brilliant colours of the
soap-bubble. Viewing it again on the second day, I observed
that the yolk had a central spot, or nucleolus, rather deeper
coloured than the rest. On the fourth day the yolk had
changed its position, and doubled in size, as shown slightly
magnified (Plate VII. fig. 1). Upon a closer examination, a
central depression, or transverse fissure, could be seen, which,
on the sixth day, plainly indicated the line of demarcation in
the little mass, as represented at fig. 2. From this time it
commenced to move round the whole interior of the cell, with
a very slow rotatory motion ; the motion was increased when
the sunlight shone upon it, from which I concluded, that, as
it received more heat, its movements were thereby accelerated.
The increase in size of the two parts of the animal appeared to
be uniform up to the sixteenth day, when the shell apparently
occupied the larger portion, represented at fig. 3; and the
spiral axis, around which the calcareous lamelle were being
deposited, had a much darker colour than the soft, or cephalic
extremity. On the eighteenth day the tentacle was visible,
with a small black speck at its root, the eye; this was seen
to be protruded with the movement of the tentacle. Upon
closely watching it, a fringe of cilia could be seen surrounding
the tentacle and oral aperture ; and, from observing the direc-
tion of the currents, I am led to believe that the earliest
rotatory motion is in a great degree, if not wholly, dependent
upon the action of the cilia. A constant current being kept
up in the cell-contents, we may conclude, that with this
motion, we have the conversion of the cell-contents into the
several tissues ; and probably the whorl-shape of the shell is
likewise due to the same formative process. The rotation
was, on every occasion of my observing it, from the right to
the left, and this always combined with a motion around the
egg ; the embryo performing a circuit, as represented magnified
at fig. 4, and forcibly reminding me of M. Wichura’s scientific
investigations into the curious property possessed by the
leaves of plants, of winding generally in a particular direction.
He observes :—

‘¢ It is a very remarkable phenomenon, that the circularly or heliacally
acting forces of nature follow an unchanging, definite, lateral direction in
their course. In cosmical nature the planets describe heliacal lines, wind-
ing to the right in space, by virtue of their circulation from west to east ;
since this is combined with the advance, in company with the sun, towards

a point in the northern hemisphere. In the department of physics we
meet with allied phenomena in the circular polarization of light, and in

Hoga, on the Water- Snail. | 93

the course of electro-magnetic spirals. Organic life exhibits the same
laws in the circulation of the blood, in all cases starting from the left side
of the animal body ; and in the heliacal windings of the shells of Mollusks,
which follow a direction determinate for every species. But plants, above
all, give evidence of a wonderful obedience to such laws, in the direction
of the spiral vessels, the heliacally winding trunks of trees, winding stems
and leaves, and probably also in the circulation of their saps.” *

Professor Quekett has directed attention to this subject,
especially with regard to plants, in his ‘ Histological Lec-
tures. ‘To proceed :—

From the twenty-sixth to the twenty-eighth day the little
animal was actively engaged in making its way out of the
egg, in the advanced stage represented at fig. 5, leaving its
_ shell behind it in the ova-sac, and immediately attaching itself
to the side of the glass. The ciliary motion is then better
seen ; each tentacle being surrounded at the extreme edge by
a row of cilia kept in motion by bands of muscular fibre : the
cilia are protruded from beneath the shell, and kept incessantly
at. work, in conjunction with those surrounding the opening to
the mouth; thus bringing a constant current of water for the
gration of the branchiz, situated above the oral aperture ;
and at the same time a due supply of nourishment for the
growth of the little animal. And it is a remarkable fact, that,
as soon as the gastric teeth are properly matured to enable
it to cut the vegetable substances growing in the water, the
cilia being no longer required, then disappear, and drop off,
from the tentacles. ‘The tentacles and oral fringe of cilia are
represented magnified, in the drawing, at fig. 6. But if, on
the other hand, the young animal be kept in fresh water
alone, without vegetable matter of any kind, it still retains its
cilia, and attains only to a small size; it then acquires gastric
teeth, but of a very imperfect character, which never attains
to perfection in form or in size. If at the same time it is
confined to a small narrow cell, it will only grow to such a
size as will enable it to move about freely; thus adapting
itself to the necessities of its existence.

Dr. Grant, I believe, first pointed out the ciliary motion in
the embryo of some salt-water species of Gasteropoda. In
examining the embryos of Buccinum undatum and Purpura
lapillus, which are also enclosed in groups within transparent
sacs, he was struck with an incessant motion of the fluid in
the sac towards the fore-part of the embryo; and he then
noticed that this motion was produced by cilia placed around
two funnel-shaped projections on the fore-part of the young

* M. Wichura, ‘“‘On the Winding of Leaves,” translated by Arthur
Henfrey, F.R.S., ‘ Scientific Memoirs,’ 1853.
hk 2

94 Hoee, on the Water-Snail.

animal, which form the borders of a cavity, in which he per-
ceived ‘a. constant revolution of floating particles. He also
observed these circles of cilia in the young of the species of
Trochus, Nerita, &c., in which the embryo was seen revolving
round its axis. He met with the same appearance in the naked
Gasteropoda, as the Doris, Eolis, &c. The embryo of these
revolve round its centre, and swims rapidly forward by means
of its cilia, when it escapes from the ovum, Dr. Grant
assigns various uses to these motions, but does not connect
them with respiration or nourishment, although there can be
little doubt that they are so.

In some six weeks, or two months, the flattened form of
the shell becomes gradually changed into that of the conical
form of the full-grown animal (fig. 7).*

That this little creature is hermaphrodite, like the common
snail, is proved by my having only this solitary animal in my
vase; and yet nearly all the eggs deposited by it arrived at
maturity. Like the common snail it is also copulative, as I
have seen two animals mutually pass a thin tongue-like organ
into a fissure between the body and upper surface of the pos-
terior portion of the foot.

I observed in the few eggs that did not come to maturity
that the yolk only slightly increased in size, and then remained
in that state until all the others were hatched, when the ova-
sac became the prey of other animals.

This one snail deposited two and three of these ova-sacs
in the course of the week; and in two months I calculated
that upwards of 800 young would result therefrom; thus
it will be seen, that the number of eggs deposited by each
individual is very great; fully explaining the rapidity with
which this class of animals increases, either on land or in
the water.

The shell, as we have before seen, is begun at a very early
stage in the formative process. It is first observed to have
the shape of minute ovoid cells, which are deposited side by
side around the axis, or central cell; and this may be
described as a cytoblast, enclosing a certain quantity of colour-
ing matter, just sufficient to give it a distinctive appearance,
from the previously-formed basement membrane. ‘The sides
of one cell being in close contact with those of other cells, a
gradual compression, or elongation, takes place, and we have,
finally, resulting divisional ribs, hardened by the deposition
of calcareous matter into a shelly covering. Subsequently all
trace of the earliest cells and cytoblasts are lost.

7

* In warm weather the eggs arrive at maturity in a much shorter time,

especially when exposed to the light and warmth of the sun.

Hoag, on the Water-Snail. ob

My own observations upon the Zimneus, in many important
particulars, coincide with those of Mr. Bowerbank, made in
1843, and published in the Transactions of this Society, upon
the Structure of Shells of Mollusca, &c. Mr. Bowerbank thus
explains the development of the shells of these animals :—

‘‘ Let us suppose the rudiment of the future shell to have been the
result of the excretion of some mucus or lymph (properly, albumen) ; it
would then be nothing more than a very thin transparent membrane, with
a determinate figure dependent upon the figure of its species. In this
membrane organizing cytoblasts and cells are produced and multiplied in
rapid succession, until, by their increase and opposition, a cellular struc-
ture is formed in it. On their first appearance the cells are transparent
and globular, but pushed on by the law of growth, which regulates their
development, they very soon begin to secrete, from their inner surfaces,
carbonate of lime. The cells being filled with it, a solid structure is the
result of their close aggregation ; the pattern being modified only by the
form and degree of condensation of the caleigerous cells, in which it has
been secreted. ‘i * % *
A layer or stratum of shell being thus formed, another is produced from
its inner surface by the same means, and then others, until the normal
set is completed: the whole being kept together as one by the living
tissues.”

Mr. Bowerbank believes that the truth of this mode of
formation is proved, not only by the structures he has dis-
covered, but also by the phenomena which occur in its repa-
ration of injuries; for he says :—

** This reparation is not made by a coat of calcareous matter, spread
over the wound by the collar or mautle of the animal, as has been main-
tained, but by an effusion of coagulable lymph, in which cytoblasts are
produced in the first instance, and quickly succeeded by a cellular struc-
ture, in which the earthy basis of the shell is secreted, and by which the
scar is filled up, or the fracture cemented together,.”’

This I have repeatedly verified, and always found that after
an injury to the shell of either an embryonic, or more perfectly-
formed animal, in a few hours subsequently the process of
repair has been commenced by a deposition of cells, less in
size, and somewhat more irregular in form than the first.
Upon breaking off an eighth of an inch from the edge of the
shell of a full-grown animal, I observed that it first threw out
a series of exudations of plasma, or albuminous matter; which,
after some days, became hardened by a calcareous deposit,
corresponding in appearance to the lines of growth of the old
shell, but only to the extent required to convert the edge into
a smooth and strong margin of about one-half the breadth
broken off; and, ultimately, new lines of growth were
thrown out beyond the edge of the mantle; this I clearly
ascertained by scraping it with a fine knife. In reference to
this part of my inquiry I may be pardoned for directing

96 Hoge, on the Water-Snail.

attention to the very interesting observations of Professor
Paget :—

“That the reparative power in each perfect species, whether it be
higher or lower in the scale, is in an inverse proportion to the amount of
change through which it has passed in its development from the embryonic
to the perfect state. And the deduction to be drawn is, that the powers
for development from the embryo are identical with those exercised for
the restoration from injuries : in other words, that the powers are the same
by which perfection is first achieved, and by which, when lost, it is
recovered. Indeed, it would almost seem as if the species that have least
means of escape or defence from mutilation were those on which the most
ample power of repair has been bestowed ; an admirable instance, if it be
only true, of the beneficence that has provided for the welfare of even the
least of the living world, with as much care as if they were the sole
objects of the Divine regard.”

Dr. Carpenter differs in some particulars from Mr. Bower-
bank, more especially with reference to the vascularity of
‘the shell, which, I believe, he entirely denies, and somewhat
inclines to the more generally received opinion of Reaumur ;
who, after careful examinations of the shells of Gasteropoda,
came to the following conclusions :—

‘‘ That these calcareous defences are mere excretions from the surface
of the body, absolutely extra-vital and extra-vascular, their growth being
carried on by the addition of calcareous particles deposited in consecutive
layers. The dermis, or vascular portion of the integument, is the secreting
organ, which furnishes the earthy matter, pouring it out apparently from
any part of the surface of the body, although the thicker portion, distin-
guished by the appellation of the mantle, is more especially adapted to its
production. The calcareous matter is never deposited in the areole of the
dermis itself, but exudes from the surface, suspended in the mucus which
is copiously poured out from the muciparous pores, and gradually hardened
by exposure ; this calciferous fluid forms a layer of shell, coating the inner
surface of the pre-existent layers to increase the size of the original shell,
or else in furnishing at particular points for the reparation of injuries
which accident may have occasioned.” *

Now, if it be a mere excretion from the surface of a mem-
brane, and neither vital nor vascular, how does Reaumur
account for the deposit of the calcigerous cells, and subse-
quent formation into shell, so early seen in the embryo; and
that long before these cells can become consolidated by
exposure to air? Mr. Bowerbank has seen, as well as myself,
that at a very early stage of embryonic life, calcareous matter
is deposited, and hardened into shell ; and this can be readily
proved, by simply breaking up the egg, and submitting a
portion of the contents to the action of a drop of very dilute
acetic acid, when the carbonate of lime will be very quickly

* ¢ Article Gasteropoda.’ By Professor Rymer Jones. ‘ Cyclopedia of
Anatomy and Physiology.’

Hoee, on the Water-Snail. 97

dissolved out, with a brisk effervescence; the basement mem-
brane only remaining, as in the older shell. _

If the young animal be viewed under a power of 150
diameters, the whole mass is sufficiently transparent, to show
that the shell is an important part of the whole structure, and
not “ suspended in mucus ;” but has a hardened and definite
form long before it issues from the egg, or comes in contact
with the external air, to produce any hardening effect upon it.

Mr. Bowerbank has observed, that in the fully-formed shell
“the mode of effecting repairs in the periostracum, affords
evidence of a high degree of vitality.” As to the term extra-
vital, | know not what it means; and, I believe, no one who
has bestowed care and attention in the investigation of the
works of the Great Creator, will for one moment assume the
smallest speck to be an extra-vital production, or addition.
Indeed, it appears to me that it would be as reasonable to
deny the vitality of bone, or the growth of the lower organized
cartilage, as to deny it to the shell of the pectinibranchial and
pulmonated Mollusks.

Dr. Carpenter says :—

““ It may now, however, be stated as an ascertained fact, that shell
always possesses a more or less distinct organic structure ; this being, in
some instances, of the character of that of the epidermis of higher animals,
Ne in others having more resemblance to that of the dermis, or true
skin.”

From repeated examinations, I believe, with Mr. Bower-

bank :-—

“‘ That the structure of shell is analogous to bone in some respects, and
is formed much in the same manner as in particular kinds of bony matter,
by the deposition of carbonate of lime within the cells of the membranes,
which enter into the composition of the shell, or by the aggregation and
coalescence of the calcigerous cells when the membrane is very sparingly
produced ; and that it is made up of three strata. Hach stratum being
formed of innumerable plates, composed of elongated cellular structure ;
each plate consisting of a single series of cells parallel to each other.
These plates of cellular structure are deposited alternately in contrary
directions, so that each series of cells intersects the one beneath it, at
nearly right angles.”

If to a portion of the periostracum a small quantity of very
dilute acetic acid be added, to dissolve out the calcareous
matter, and it be then viewed under a magnifying power of
250 diameters, it will be seen to be composed of oval cyto-
blasts, exhibiting distinct nuclei, beneath which will be found
a fine membrane studded with minute spots, apparently the
escaped contents of the cells. This membrane has a regular
series of corrugations or folds arranged throughout its whole
extent, which gives to the shell in certain positions an

98 Hose, on the Water-Snail.

iridescent lustre. Immediately beneath this is placed the
transparent basement membrane of an even texture and very
light amber colour, this is the albuminous or animal mem-
brane ; which with the layer before referred to, and above this,
appears to me to be traversed by tubes, that no doubt run
from the inner to the outer portion of the shell substance, and
probably this net-work of pores have assigned to them similar
duties to those in the human skin, viz., that of throwing off
effete particles of matter, &c.

The very small proportion of animal matter contained in
this shell is a marked characteristic ; after the removal of the
calcareous matter by dilute acid, we have the small residuum
of a grain or two only ; from this cause the shell is very brittle
at all times. The shell of the fully-formed animal is ovate,
whorls five or six, elongated and dextral; thus favouring, as
before observed, the notion that the circular motion of the
embryo when in the egg determines the whorl.*

The mantle of the animal partakes of the same character
and structure as that of mucous membrane generally, more
especially that portion of it lining the internal surface of the
shell; thence itis reflected over the body, and forms a direct
communication with the external shell and internal soft parts.
Its other important use, besides that of depositing carbonate
of lime, is the secretion of plasma, or a glazing fluid, which
it spreads over the internal portions of the shell, and with
which it lubricates the whole of the external parts, thus pre-
venting any irritation that might arise from a drying up of |
the coarser particles of calcareous matter. Another use I
have particularly noticed, is that of converting a large part of
it, beneath the greater whorl of the shell, into an air-bag, or
receptacle for holding a bladder of air, which must have consi-
derable influence in rendering the shell buoyant and light, as
by suddenly discharging it, the animal instantly sinks to the
bottom. The animal is often seen to rise to the surface of
the water for the purpose of taking in a supply of fresh air,
which it does by opening a small valvular aperture, situated
about the eighth of an inch above the ventral outlet. If the
animal be removed from the water it immediately squeezes
out this supply of air, at the same time it presses out the
water from the body, for the purpose of enabling it to recede

* For further information and much interesting matter upon this sub-
ject I must refer to Mr. Bowerbank’s researches upon the ‘ Structure of
Molluscous and Conchiferous Animals,’ most accurately and carefully
illustrated, published in the Transactions of this Society, 1843. Also Dr.
Carpenter’s researches, published in the Reports of the British Association,
1844 and 1847; and his ‘ Principles of General and Comparative Phy-
siology.’

Hoaa, on the Water- Snail. 99

into the interior of its shelly house for protection ; in this act
it is greatly facilitated by the action of retractor muscles,
having a strong tendinous attachment to the columella of the
shell. Theshell of the young animal, and thin portions of the
older shell, viewed by polarized light on the selenite stage,
are interesting and beautiful objects. In the young animal
the growth of the membranous part is effected by the gradual
expansion of the vascular and cellular tissues, and we are
soon enabled to define the expanded foot. This is a fleshy
disc, broader anteriorly and divided into transverse segments ;
by a particular arrangement of the longitudinal muscular
fibres it is enabled to perform a series of undulatory move-
ments, by which means the animal glides smoothly along; its
under surface is likewise studded over with a number of small
orifices, which assist in causing a vacuum to be formed, and
thus it suspends itself in an inverted position from the surface
of the water, moving about in any direction, The muscular
fibres, by their interlacements, greatly assist the animal in its
progression, and in the performance of rapid movements; at
the outer edge it is, turned over, or returned upon itself,
forming a smooth and strong margin of condensed tissue and
muscular fibres, which take their course in broad fasciculi, and
gradually taper off toa thin tendinous attachment on the pillar
of the shell.

The mouth is situated at the under and fore-part of the
head ; it is a muscular cavity, enclosing a dental apparatus,
semicircular in shape and provided with transverse rows of
projecting spines, or teeth of a horny structure, or, more
correctly, alternating rows of incisor and canine teeth, each
being pointed with silica, and accurately fitted to cut against
each other; they are thus admirably adapted for the scraping
or stripping off the cuticle from the blades of Vallisneria,
which the animal does without killing the plant, and leaves it
more accurately divided, than at all possible to obtain by the
usual mode of splitting for microscopic observation. The
gastric teeth are immediately joined to the csophagus or
gullet, and to this succeeds the gizzard, a strong muscular
apparatus, a quarter of an inch in length, and having a rugose
appearance, with transverse and longitudinal fibres, by means
of which every movement requisite for the conversion of the
food is effected, and passes into a small membranous sac, the
stomach ; this is folded into longitudinal plice, and from it
arises the large intestine of considerable length, having much
of the appearance of intestine in the higher order of animals,
excepting in colour ; a narrow longitudinal band passes down on
either side of the external coat, and internally it is apparently

100 Hoee, on the Water-Snail.

supplied with valves. In its course it takes a considerable
turn around the inner whorls of the shell, terminating in a
rectum which has its vent placed between a small portion
of the mantle and the under edge of the last whorl of the shell.

The liver is not nearly so large as it is in the land-snail ; it
consists of two lobes, and is enclosed in a strong capsular
covering ; it pours a pale-coloured bile into the stomach by
more than one duct, and is provided with a proper hepatic
system of vessels.

The heart is a strong muscular apparatus, having both an
auricular and ventricular cavity; it is surrounded by a very
delicate membrane (the pericardium). In shape it is pyriform,
with muscular cords stretching from side to side, of a highly
elastic character, looking not unlike very fine bands of India-
rubber alternately contracting and expanding ; these cords are,
no doubt, analogous to the corde tendinee of the mammal
heart. ‘The heart receives the erated blood from the respira-
tory organs, and propels it through the vessels at the rate of
sixty times a minute. It is placed far back in the superior
portion of the shell, near to the axis, where itis securely fixed
without reference to the movements of the mouth or body of
the animal.

Like others of this family of aquatic Gasteropoda, the
breathing apparatus resembles the branchiz of fishes in struc-
ture ; they are pectinated, and placed in three or four rows
near the roof of a cavity under the integuments of the head,
or rather above the oral opening, which is peculiarly arranged
with retractor and other muscles, for the purpose of permitting
an uninterrupted eration of the blocd as it is brought to the
branchie.

The nervous system consists of many gangliz, or nervous
centres, in place of a distinct brain, but “each of these
gangliz may be considered as a distinct brain of the hetero-
gangliate form.’ They are freely distributed throughout the
body, but connected with each other by cords of communica-
tion ; the nervous mass appears to be granular, and is some-
what yellow in colour, whilst the nerves themselves are white
and smooth, and invested with a delicate membrane (neur?-
lemma). Professor Jones observes that—

‘‘ One remarkable circumstance may be mentioned as peculiar to this
class ; the changes of position of the nervous centres obey the movements
of the mouth, with which they are intimately connected ; they are, in
fact, pulled backwards and forwards by the muscles serving for the pro-
trusion and retraction of the oral apparatus, and are thus constantly
changing their relations with the surrounding parts.

‘“«' he ganglia, placed above the cesophagus, sends off branches to supply
the muscles of the head, the tentacles, and give origin to the optic nerves ;

Hoge, on the Water-Snail. . 1Or

and from the sub-cesophagial ganglion, which fully equal the former in
size, arise those nerves which supply the muscles of the body, and of the
viscera.” *

The singular adaptation of the eye must not be omitted ;
this appears in the early embryonic stage to be situated within
or on the tentacle, it is constantly retracted with it, which is
due to the length of the pedicle, and to the retractile sheath
of the optic nerve, enabling the animal to shorten it; at the
same time the tentacle folds down over it, forming a protec-
tive cover at all times. The eyes are situated at the base of
the inner side of the tentacle, and resemble two very small
black spots. When examined with a power of 100 diameters,
they are seen to be transparent spherical lenses, surrounded
by a black zone or iris, the pigmental layer is continued some
distance down the pedicle. It is pear-shaped, and evidently
the little animal is very quick-sighted, as he avoids every
obstacle placed in his way, or quickly withdraws himself into
his house if one attempts to touch him; although in avoiding
obstacles he appears to make great use of his tentacles as true
feelers. ‘The tentacles are composed of a dense elastic tissue,
surrounded by a band of muscular fibre ; in shape they are
triangular, with the base attached to the body of the animal.

The Limnei are stated by Professor Forbes to have been
found in the fossil state as far back as the Oolitic epoch; and
the most ancient forms bear a striking resemblance to the
common existing types. In England, at the present time, they
are abundant in nearly all the waters where vegetable matter
is growing, and in the slow running rivers, especially where
the water-cress is found.

The Limneus, like every other living thing, is infested with
its parasite. Reaumur observed a sort of mite infesting the
snail (Helix aspersa), they were securely lodged in the pul-
monary cavity. Miiller also noticed in certain Gasteropods a
worm; and Dr. Gould, examining a specimen of the Physa
heterostropha, “found the neck of the animal beset with
numerous little things, looking like short, minute, white lines,
attached like leeches, and which derive their nourishment
from the fluids of the animal without his having the power to
dislodge them.” ,

M. Baer states that he discovered a Filaria in the abdomen
of Limneus stagnalis; and in many of the same family of
Mollusca he has met with a worm allied to the Naides,
“‘ living in the respiratory cavity, or hanging like little tufts
of threads from the sides of the abdomen; whence he named
it Chelogaster.” Besides these, he says, “ a kind of Cercaria

* Professor Rymer Jones, op. cit.

102 Hoae, on the Water-Snail.

finds an appropriate nidus for their evolutions in the body of
the lacustrine snails ; and the curious transmutations of form
they undergo in the interior of the animals, and the circum-
fluent water, afford one of the most striking illustrations of
Steenstrup’s theory of alternating generations.” *

Upon observing the Limneus in my glass rather closely, I
noticed that its body was covered with the “ little white line-
lookiny leeches,” described by Dr. Gould and M. Baer; upon
carefully detaching one or two, and viewing them with a half-
inch object-glass, it had the formidable appearance represented
in the drawing at fig. 8. It has an anterior mouth, surrounded
with minute teeth or spines, over which it possesses great
power. Suddenly it may be seen to dart out its body, at the
same time projecting its mouth to some distance apparently for
the purpose of seizing its prey, when it as quickly retracts
itself within the shell of the animal, where it securely attaches
itself to its body by a posterior sucker. It is possessed of a
great number of hooklets or feet, by these it creeps from one
part of the body to another, but is always found adhering to
those parts affording security in times of danger. Eventually
they become so numerous that the animal’s life falls a sacrifice
to its troublesome tormentors, having apparently no power to
rid itself of them.

In conclusion, I would offer a word or two on the cell ; the
primordial wall of which does not enter into the formative
process of the embryo. The cell contents only are required
for the purpose of affording nourishment to the vital blastema
of the nucleus, in which a cycle of progressive development
once set up, goes on until the animal is sufficiently matured to
break through the cell-wall,and escape from the ova-sac. At the
same time it may be inferred, that this is in some way assisted
by the process of endosmose, and in this way certain gases
or fluids become drawn into the cell-interior, and thus mate-
rially aid in the supply of nourishment for the growth of the
animal.

The cell-wall bears the same relation to the future perfect
animal that the egg-shell of the chick does to it; it is but an
external covering to a certain amount of gaseous and fluid
matter, and for the purpose of placing the germ of life in a
more favourable state for development, assisted as it is by
an increase of temperature usually the result of a chemical

action set up, or once begun, in an organism and a medium.

The ovum, destined to become a new creature, originates from
a cell enclosing a gemmule, from which its tissues are formed,
and nutriment is assimilated, and which eventually enables

* Avassiz and Gould’s ‘ Principles of Zoology.’

Hoae, on the Water-Snail. 108

the animal successively to renew its organs through a series
of metamorphoses, which give it permanent conditions not
only different but even directly contrary to those which it had
primitively. —

In this one fact are we not furnished with a well marked or
broad line of demarcation between that of animal and vege-
table life? In the development of the animal, the cell-wall
takes no part in the formative process ; it is but an enveloping
membrane required for a time, and then thrown off. On the
contrary, in vegetable life it enters largely into the formative
process, and ultimate development of all its tissues; it.is ever
to be found growing with its growth, cell-wall upon cell-wall
intact, with or without its earliest contents.

Note.—June 6th, 1854.

My attempt to arrest the development of some young
animals is still continued with perfect success. They have
remained in the same narrow glass-cell, at the stage of growth
before referred to, viz., about the size the animal usually
attains during the first two or three weeks of its existence.
They are now siz months old, alive and well, the cilia are re-
_ tained around the tentacles in constant activity ; whilst other
animals of the same brood and age, placed in a situation
favourable to growth, have attained their full size, and have
now produced young, which are of the size of their elder
relations, _

DESCRIPTION OF PLATE VII.

Fig.
1.—A magnified representation of the increase and change of situation
occurring to the yolk of egg of Limneus on the fourth day.

2.—The change observed on the sixth day, showing the transverse fissure
or divisional line in the mass.

3.—The formation of the shell proceeding more rapidly, it appears on the
sixteenth day as the larger portion of the embryonic mass.

4,—The embryo performing its heliacal windings around the shell.

ore Tye or young animal, seen soon after it has issued from the
shell.

6.—The tentacles, with cilia, seen under a 3-inch object-glass ; the arrows
indicating the course of the current produced by the cilia.

7.--The natural size and form of the shell of a full-grown Limneus.

8.—Parasitic animal found on the body of Limmneus, magnified 100
diameters.

104 Greeoory, on Fossil Diatomacce.

Observations on some Deposits of Fossil Diatomaces. By
Witiram Grecory, M.D., F.R.S.E.

(Read April 19th, 1854.)

In the series of microscopic objects issued by the Zurich
Microscopical Association, there occurs a specimen of Berg-
mehl, stated to be from Lillhaggsjon in Lapland, which is
very remarkable in several particulars.

First, there is a very great abundance of Hunotia Triodon,
exhibiting the most astonishing variations of outline, so that
the extreme varieties in opposite directions, those, for ex-
ample, which are short, compressed, and have strongly-marked
prominences, and such as are long, flattened, the apices being
lengthened out, while the prominences actually disappear, or
can only be traced by a hardly-perceptible waviness in the
dorsal outline, would hardly be supposed to belong to the
same species, and yet a perfect and gentle gradation may be
traced from the one extreme to the other. This remarkable
tendency to vary in form is peculiar, among the Eunotie I
have seen, to this species, EL. Trzodon and to E. begebba, Kiit-
zing. Itis totally absent in the common fossil forms of £.
Tetraodon and E. Diadema, which hardly vary at all, save in
size.

It appears to me that this fact, especially when we consider
that all these species often occur together, as, for example, in
the Mull deposit, where £. Triodon, though not frequent, is
just as variable as in the Bergmehl under consideration,
demonstrates that these species are really distinct, and not, as
some have conjectured, varieties of one, which may present
one, two, three, four, five, six, seven, or more prominences.
If all belonged’to one species, all should be alike variable or
alike constant, whereas some vary ad infinitum, others not at
all, in form at least. Nor can it be said that such a form as
E.. Triodon is developed, as a variety, only under certain cir-
cumstances; for in the Mull deposit it occurs with all its
peculiarities, and therefore the supposed circumstances must
have occurred; and yet, in that deposit, HE. Tetraodon and
E. Diadema are much more abundant, and show no tendency
to vary inform. But these two last-named species are absent
from this Lapland deposit, where EL. Triodon abounds, It
seems to me that these facts settle the question as to the
species named, which must be held to be true and well-
marked species; one of the characters of EL. Triodon and of
E. begebba being a tendency to vary in form, while fixity of
form characterises H. Tetraodon and EL. Diadema.

This Laponian deposit also contains E. serra, and I think

Greeory, on Fossil Diatomacee. 105

I have seen LE. heptodon. E. serra seems to be confined to
Scandinavian deposits.

Although differing from the Mull deposit in regard to the
forms I have named, and also some others, this Bergmehl
agrees with it in many points, as in the abundance of Navicula
rhomboides and JN. serians, that of many Pinnularie, of Gompho-
nema coronatum, of several Cymbelle, Stauroneides, Tabellaria,
Orthosire, and other forms, but especially in the presence of
Funotia incisa, first observed by me in the Mull earth. The
’ variety 6 is here the more frequent.

There is another form, common to these two deposits,
which, so far as I know, has not been described. It is an
aspect like a Synedra, long and narrow, straight in the middle,
and having the ends curved opposite ways, which gives to it
a sigmoid character. I am inclined, however, to suppose it
to be a Mitzschia, for while 1 cannot make out the transverse
strie of Synedra, I can see a row of puncta on each margin
in some specimens. It is, however, quite distinct from
NV. sigmoidea. In the Mull earth it is generally broken, so that
we see only one-half; but I have found several entire ex-
amples. In the Lapland deposit it is more frequent, and
often entire, although from its slender proportions it is apt to
be broken, and fragments also occur. As we have already
Nitzschia sigmoidea and N. sigma, this form, if it be a
Nitzschia, may be called N. sigmatella.

I have still to notice a form occurring in this Lapland Berg-
mehl, which, so far as I have been able to ascertain, is un-
described. It is narrow and of considerable length, but bent
into the form of a sickle, or nearly a semicircle. It is slightly
attenuated at the rather acute apices, and has very strong and
distinct, though rather fine, transverse strie. It approaches
more nearly to Hunotia arcus, as figured by Smith, but differs
entirely from it, in being much more curved, in the absence
of the characteristic prominence in the so-called ventral
surface, and in its having much stronger and more distinct
strie, all of which characters combined give it an entirely
peculiar aspect. Taking it, for the present, to be a Hunotia,
I propose for it the name of Hunotia falz, or E. falcata.

I would now direct attention to a deposit, of which speci-
mens were sent to me by Mr. Norman, under the name of
Liineburg. It is well known that there is an extensive de-
posit on the Liineburg heath, in Hanover, and one part of it
is known as the earth or Bergmehl of Oberrohe, near Liine-
burg, another as that of the Limeburg heath. These I find to
be quite distinct from the deposit of which I now speak, as
obtained from Mr. Norman; for this, as I have found, has a

106 Greeory, on Fossil Diatomacee.

composition absolutely identical with that of the Lillhaggsjon
Lapland deposit I have described. Not only the species are
the same, but they are in the same proportions. In both
Eunotia triodon presents in abundance its strange variations ;
in both the long sigmoid form, and also the sickle-like form,
occur.

In short, I can detect no difference between these two de-
posits; besides the forms I have named, both contain Hunotia
incisa, chiefly var. 8; and both alike contain such forms as
Eunotia serra, Tetracyclus lucustris, and others, imasmuch that
I think it more probable that one of them has been misnamed,
than that two deposits, in places so distant as Limeburg in
Hanover, and Lillhaggsjon in Lapland, should be identical in
composition. Since all the specimens of earth from Oberrohe
near Liineburg, and the Liineburg heath, that I have examined
(and I have seen several different specimens in the natural
state), differ from the Lapland earth, and since the Lapland
earth is referred to its locality by the Zurich Association, |
conclude that the earth in Mr. Norman’s hand is really not
from Liineburg, but from Lapland. Perhaps there may be a
place called Lineburg in Lapland, near Lillhaggsj6n ; but this
I have not been able to ascertain. In the mean time, this
so-called Liineburg deposit will supply observers with the
two forms I have now described. I have noticed it in some
other forms which I believe to be undescribed ; to these I
shall return on some future occasion.

TRANSACTIONS OF MICROSCOPICAL SOCIETY.

DESCRIPTION OF PLATE I. VOL. II.

1. Bacteriastrium furcatum.
2. — curvatum.
3. Euphyllodium spathulatum.
4. Triceratium sculptum.
5
6

— arcuatum.

— arbiculatum.

7a. Triceratium contortum.

*7b, —————— do. showing spine.
8. Pleurosigma vallidum.

9. ——-——-— inflatum.

10. Amphitetras arisata.

11. tessellata.

12. Hupodiscus crucifer.

13. Campylodiscus latus.

14, Asterolampra impar.

15a & 15b. Climacosphenia catena.
16. Denticella simplex.

Ee. margaretifera.

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TRANSACTIONS OF MICROSCOPICAL SOCIETY.

DESCRIPTION OF PLATE II.

Figs. 1, 2, 3, 4, 5.—Avicularium of Notamia bursaria.

L—Avicoleriam in the closed state.

2.—Avicularium open, exhibiting the tactile (?) brush.

3.—Avicularium viewed in front, to show an opening below the beak.

4.—Avicularium in the early stage of developement.

5.—Closed avicularium, more magnified, showing the muscular structure
and the internal organ.

Figs. 6, 7, 8.—Avicularium of Bugula plumosa.

6.—In the closed state.
7.—Open, showing the tactile (?) brush.
8.— Open, to show the diaphragm,

Figs. 9, 10, 11.—Avicularium of Bugula avicularia.

9.—Open, to show the tactile (?) brush (more magnified).
10.—Two avicularia grasping each other,
11.—One partially open (less magnified).
12.—Avicularium of Scrupocellaria scruposa.
13.—A small vermicule captured by two avicularia in Scrupocellaria
scruposa.
14.—Avicularium of Bugula plumosa, in the early stage of developement.

DESCRIPTION OF PLATES IIL, IV., & V.

Tllustrating Professor Quekett’s Papers on me Torbane-hill
Mineral.

PLATE III.

Fig.

food section of the yellow variety of the Torbane-hill Mineral, as seen
under a magnifying power of 130 diameters.

2.—A section of the dark variety of the Torbane-hill Mineral, as seen
under a power of 130 diameters. The yellow circular masses exhibit

~a radiated structure; they form the combustible portion of the
mineral, whilst the dark matter is the earthy ingredient.

3.—A section of the Torbane-hill Mineral, in which a specimen of Stig-
maria ficoides is imbedded : every part of this plant can be readily
distinguished from the mineral by its rich brown colour. Mag-
nified 6 diameters.

4,.—A portion of the same specimen magnified 50 diameters, showing how
easily the smallest portion of vegetable tissue can be distinguished
from the substance of the mineral.

5.—A section of the Torbane-hill Mineral, through which .a thin layer of
coal ran, which may be readily recognised by its brown colour.
The yellow particles of the mineral in contact with the coal are of
more or less oval figure.

6.—The powder of Torbane-hill Mineral, showing the yellow bituminous
particles, and fragments of vessels.

7.—Ash of the Torbane-hill Mineral.

PLATE IV.

1.—Transverse section of the Brown Methil Coal.
2.—Longitudinal section of the same.

3.—Transverse section of the Black Methil Coal.
4.—Longitudinal section of the same.

5.—Transverse section of the Lesmahagow Cannel Coal.
6.—Longitudinal section of the same.

PLATE V.

1.—A section showing the Mineral and Coal in juxtaposition ; magni-
fied 3 diameters.
2.—Representations of the comparative sizes of the transverse sections of
the brown elongated cells from various Coals, drawn by means of
the camera lucida, by Dr. Adams, 70 diameters.
3.—Chippings of Newcastle Coal, showing dotted woody tissue.
4.—Ash of common domestic Coal, exhibiting the remains of a transverse
section of wood.
5.—A. longitudinal section of Coal from Lochgelly, showing its identity
with a similar section of wood, from a drawing in the possession of
Dr. Adams.
6.—Ash of Coal, exhibiting portions of siliceous cuticle and other frag-
ments of vegetable tissue foreign to the coal.
7.—Powder of Breadisholme Coal, from a drawing by Dr. Adams.

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DESCRIPTION OF PLATE VI.

1.—Cocconeis placentula.
2.—Actinocyclus sedenarius ?
3.—Triceratium striolatum.
4.—Campylodiscus bi-costatus.
5.—Zygoceros Rhombus.

6 a.—Odontidium Harrisonii ?

6 b.— ee front view.

7.—Rhaphoneis gemmifera.

8.— oe fasciolata.

9.— Gs pretiosa.
10.— “ rhombus.
11.—Zygoceros Surirella; front view.
12,— 5 side view.

99
13.—Front view of Actinocyclus sedenarius, showing the undulations.
14.—Side view of the same, showing the cellular markings.

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TRANSACTIONS OF MICROSCOPICAL SOCIETY.

DESCRIPTION OF PLATE VII.

To illustrate Mr. Hogeg’s Paper on the Development and Growth
of the Water-snail.

Fig. |
1.—A magnified representation of the increase and change of situation
occurring to the yolk of egg of Limneus on the fourth day.

2.—The change observed on the sixth day, showing the transverse fissure
or divisional line in the mass.

3.—The formation of the shell proceeding more rapidly, it appears on the
sixteenth day as the larger portion of the embryonic mass,

4.—The embryo performing its heliacal windings around the shell.

5.—The embryo, or young animal, seen soon after it has issued from the
shell.

6.—The tentacles, with cilia, seen under a 4-inch object-glass; the arrows
indicating the course of the current produced by the cilia.

7.—The natural size and form of the shell of a full-grown Limneus.

8.—Parasitic animal found on the body of JLimneus, magnified 100
diameters.

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INDEX TO TRANSACTIONS.

VOLUME TI.

A.

Actinophrys Sol, remarks on, by
kh. 8. Boswell, 25.

B.

Binocular vision, on the application

of to the microscope, by F. H. Wen-
ham, 1.
Boswell, R. "S., remarks on Actino-

phrys Sol, 25.

Busk, G., FRS., on the structure
and function of the avicularian
and vibracular organs of the Poly-
zoa, 26.

Diatomacez, new forms of, from Port
Natal, description of, by G. Shad-
bolt, 13.

ie of the» Thames, some
observations on, by F. C. S. Roper,
F.G.S., 67.
H.

Hogg, Jabez, observations on the
development and growth of the
Water Snail (Limneus stagnalis),
al:

Lip

Illumination of transparent objects,
on a method of employing artificial
light for, by G. Rainey, M.R.C S.,
23.

ie;

Legg, M. S., A.I.A., observations on
the examination of Sponge-sand,
19:

Limneus stagnalis observations on
the development and growth of
the, by Jabez Hogg, M.R.C.S., 91.

M.
Microscopical Society, Report of the

Fourteenth Annual Meeting of the,
81.

Bs

Polyzoa, remarks on avicularian and
vibracular organs of, by G. Busk,
F.R.S., 26.

Q.

Quekett, John, on the minute struc-
ture of the Torbane Hill mineral,
34,

R.

Rainey, G., M.R.C.S., on a method
of employing artificial light for the
illumination of transparent objects,
23.

Report of the Fourteenth Annual
Meeting of the Sue So-
ciety, 81.

Roper, F. C. S., some observations on
the Diatomacee of the Thames, 67,

Ss.

Shadbolt, G., description of some new
forms of Diatomacee from Port
Natal, 13.

Sponge-sand, observations on the ex-
amination of, &c., by M.S. Legg,
A.I.A., 19.

Tt:

Torbane Hill mineral, or Boghead
coal, on the minute structure of, by
John Quekett, 34.

Ww.

Water Snail (Limneus Stagnalis), J
Hogg, on the development and
growth of the, 91.

Wenham, F. H., on the application of
binocular vision to the microscope,
1.

th ae
| ae ee ae. osiy
oa ,

TRANSACTIONS

OF THE

MICROSCOPICAL SOCIETY

LONDON.

DA

NEW SERIES.

a,

VOLUME IIL.

LONDON:
SAMUEL HIGHLEY, 32, FLEET STREET.
1855.

LONDON: PRINTED BY W. CLOWES AND SONS, STAMFORD STREET,

TRANSACTIONS

OF THE

MICROSCOPICAL SOCIETY

OF

1; ON DON.

—-———

Some Remarks on obtaining Puorocrarus of Microscopic:
OsseEcts, and on the CoinciDENCE of the CHEMICAL and
VisuaL Foct of the OBsect Giasses. By F. H. Wennam.

(Read November 22nd, 1854.)

In this communication it is not my intention to give a detailed
description of the well-known methods of obtaining micro-
photographs, which have already been explained in the papers
of Messrs. Delves, Shadbolt, and others, but merely to point
outa remedy for some of the difficulties that have hitherto
been connected with the process.

The main points in this paper were read at the last meeting
of the British Association for the Advancement of Science, at
Liverpool, but I have thought it proper to bring them forward
again, as I believe that the principal number of those who
have entered into the practice of this department of photo-
graphy are members of the Microscopical Society.

As it is now upwards of two years since the announcement
was first made, and from the few specimens that have been
produced since that period (many of which are in the hands
of our Society), it may fairly be assumed that the practice of
microscopic photography has not become by any means uni-
versal, and, in fact, there are some amongst us who doubt
whether the art can ever be usefully applied, or prove a sub-
stitute for the camera lucida. I should regret to see this
application of the microscope abandoned, while it is still
under the march of improvement, and while science can
furnish us with new facts to facilitate the process. The con-
clusion that I have arrived at, derived from my own practice,
is, that it is in general both easy with respect to manipulation,
rapid in production, and faithful in delineation, and I have a
favourable opinion of its utility. There are some exceptional
cases, which I shall notice. How far the specimens that I
herewith present to the Society will bear me out in this assur-

VOL. III. b

2 Wenuam, on Microscopic Photography.

ance, others will probably be better able to judge than myself.
I have not worked at it with sufficient diligence to make a
choice selection, but have taken them as they came. I should
judge that the whole of them, to the number of twenty-two,
had occupied about six hours of sunlight, of course including
some failures.

If the photographs are intended for illustration, it is re-
quisite that they should each be included in a given space.
The position of the sensitive surface must in consequence be
made to vary, more or less, for every different object, accord-
ing to its size. A range of from five to ten feet is oftentimes
required. A box of this length is both inconvenient and
cumbrous, and it is a matter of some difficulty to get access to
the furthest end for the purpose of focussing the object accu-
rately. For these and other reasons, I have altogether aban-
doned the use of the microscope camera, and given the
preference to the method herein described.

In the first place, it may be proper to offer a few remarks
on the subject of the illuminating source, as I have tried many
experiments with the view of obtaining an artificial light suit-
able for photographic purposes. A light may appear strongly
luminous, and yet possess but a feeble degree of photographic
intensity ; and [ have not yet succeeded in producing a satisfac-
tory result from either gas, oil, or camphine lamps. Burning
phosphorus will give a more rapid impression, but its use is
both inconvenient and expensive. Fine zinc turnings, burnt in
atmospheric air, equal or surpass this; a ball of about three-
quarters of an inch in diameter will last a sufficient time to
give a distinct impression. As it is of no consequence whether
the light is intermittent or not, I have produced an image
from a succession of electric sparks, arising from the spon-
taneous discharge of a small Leyden jar, containing about thirty
inches of coated surface, the discharging knobs being placed
in the axis of the lenses for condensing the light upon the
object. The electric spark contains a large proportion of the
actinic rays ; I found that about one hundred discharges pro-
duced a good impression. The electric light between charcoal
points I have not yet tried. Ina few instances I have used
the hydro-oxygen, or lime light, but I consider that it does
not possess that degree of actinic intensity which its brilliancy
and appearance would seem to indicate.

It has been proved that the two latter may be successfully
applied for obtaining photographic impressions, but they are
both troublesome and too much out of the way of the micro-
scopist to be generally useful.

I have merely mentioned these experiments with the view

Wenuam, on Microscopie Photography. : 3

of recording them for the guidance of other experimentalists,
for I have a strong belief that such an investigation may end
in a useful result. There can be no doubt that it is a desi-
deratum to discover a composition for a photographic fusée, so
to term it, that will burn for a sufficient period of time, and
with the requisite actinic intensity for obtaining, not only
microscopic impressions, but also nocturnal, or underground
photographs. I trust, therefore, that this subject may be taken
in hand by some one more practically conversant with the
details of pyrotechnic chemistry than myself.

- There is no light that has hitherto been found that will give
results at all equal to those to be obtained by the use of sun-
light. The method that I have adopted for applying it, is simply
to use the ordinary table microscope as a solar one. A room is
selected, to the window of which sunlight must have free
access ; this is closed by a shutter, having an aperture at the
lower end of about three inches in diameter; below this is
placed a level table or bench at a convenient height, so that
when the microscope body is in a horizontal position, its axis
may coincide with the centre of the aperture in the shutter.
Outside the latter is fixed a solar reflector, which may be
adjusted from the inside, or more simply through a sleeve
fastened around a hole in the shutter; in this case the mirror
may be mounted entirely in a wooden frame.

With this arrangement the course of proceeding is as fol-
lows: having clamped and adjusted the object on the stage
of the microscope, place it horizontally against the aperture
in the shutter, remove the eye-piece, and throw sunlight
through the object by means of the solar reflector ; lay a black
cloth around the microscope so as to stop out all extraneous
light ; then, by properly focussing, a distinct image may be
obtained upon a paper screen held at various distances.

The stand for supporting the collodion plate consists of a
vertical piece of board with a heavy base; the excited plate
is held on to this by means of two undercut fillets at right-
angles to each other. The stand may be set at various dis-
tances along the horizontal bench, which also serves as a
support for the microscope.

The operation of taking the photograph is, first to adjust the
mirror for light, and then to focus the image on a card placed
in the plane of the collodion surface ; next remove the card and
lay it against the body of the microscope, so as to stop off all
light ; then drop the sensitive plate into its place, snatch the
card away, and quickly replace it again, so as to let the image
of the object fall upon the plate: a fraction of a second is
oftentimes sufficient. I prefer a rather slow collodion, and if

b 2

4 Wenuam, on Microscopic Photography.

the weather is warm develop with a half-grain solution of
pyrogallic acid.

For the lowest powers, it is oftentimes not necessary to use
any arrangement for condensing the sunlight upon the object,
the simple reflection from the plane mirror being sufficient ;
but the half-inch object-glass, and upwards, requires a bull’s-
eye lens of about three inches in diameter. If the objects are
small and delicate, such as the Diatomacee, the achromatic
condenser must be used in combination. _I should mention
that a piece of yellow glass must be let into the upper
portion of the shutter, transmitting enough light to manipu-
late by.

Having briefly described the method of operating, I will
state what I consider to be its peculiar advantages. ‘The
object is focussed with great facility and certainty. We are,
in some cases, enabled to obtain an impression of an object
mounted so as to be out of a flat plane ; in some instances, by
the convenience afforded for inclining the sensitive plate at
every angle relative to the optic axis, and in others by focus-
sing two or more separate times. For example, suppose the
object to be a Fly’s foot, one of the pads of which lies in a
lower plane, and is consequently out of focus; while the im-
pression of the first half is being taken, the next which is out
of focus can be stopped off with a card; the second focus is
then taken, and the first impressed portion of the object ob-
scured: thus by a diversified series of paper stops, we may
approximately represent the entire form of an object, the
whole of which cannot be seen, except by a series of three or
four focal adjustments.

A very great number of microscopic preparations are so
organized as to be composed of parts which require different
periods of exposure to produce a perfect impression ; some
parts will be barely defined, while others are utterly solarised
and lost from over exposure. The method that I have ex-
plained affords especial facilities for stopping off the most
tender portions.

As it is requisite for the purpose of ensuring quick and
accurate focussing, together with the most distinct impressions,
that the actinic and visual foci of the objective should be coin-
cident, I give the result of my investigations on this point.
For the highest powers the difference is sometimes so small as
to render the correction a matter of trifling importance; but
with the 4 inch, 1 inch and 1% inch, the distance is very
considerable; in fact, the more perfect the object-glass for
microscopic purposes, the less is it suited for a photographic
lens. The object-glasses are invariably what is technically

ae

Wenuam, on Microscopic Photography. D

termed ‘‘ over corrected ;” for the point of convergence of the
chemical rays near the most refrangible or blue end of the
spectrum, lies beyond the visual focus. I have an objective
corrected specially for these rays, and though perfect for pho-
tographic purposes, yet on account of its being non-achromatic,
it is unsuited for microscopic investigation.

The simplest and cheapest way of producing the required
degree of “ under correction,” is to screw a biconvex lens into
the place of the back stop of the object-glass, acting as part
of its optical combination For Smith and Beck’s 14 inch, I
have used a lens of 8 inches focus, and for the 2-3rd, one of
5 inches, which also serves for the 4-10th inch ; these bring
back the actinic to the exact position of the visual focus.
The combination used as an objective shows some colour, but
the additional lens does not affect the spherical correction to
any material extent, and the increase of distinctness in the
photographs obtained by means of the application of this
additional lens is most striking.

It must not be supposed that the focal lengths that I have
here given of the correcting lenses will in all instances serve
for the objectives above named, for the correction will probably
require a lens of a different focus for every different object-
glass; it is, perhaps, best to be provided with several of them,
as their cost is but trifling. Those that I have made use of
have been selected from ordinary spectacle lenses, most care-
fully centered and turned down to the required size.

Some remarks have been published on the possibility of
obtaining stereoscopic pictures of microscopic objects by
means of the “binocular microscope,’ but the ordinary in-
strument will answer every purpose without any optical
addition whatever, for it has been shown* that if the object
itself be viewed alternately with the right and left half of the
object-glass without any altering of its position, the difference
in form of the resulting images assimilates to the effect of a
different angle of vision; and if two photographs of the object
obtained by the separate halves of the object-glass be placed
in the stereoscope, they will give an appearance of solidity
to the object. The only addition that is required to produce
this effect is to fix a sliding stop close behind the objective,
having straight edges that will cut off either the right or left
hand sides ; a photographic impression being taken at the two
extremes. If the object-glass be one of considerable aperture,
about one-third only of the diameter may be cut off, which
will be sufficient to give the difference of form required for the
stereoscopic image.

* ¢ Quarterly Journal of Microscopical Science,’ for July, 1853.

6 Wenuam, on Microscopic Photography.

It is most remarkable how an impression of the finest details
of an object, or the markings on even the most difficult tests,
may be obtained by means of the photographic microscope,
and so definitely that I have used it for proving their struc-
ture.*

The application of photography to the delineation of
microscopic objects is somewhat limited, not by any diffi-

culties or defects in the process, but by occasional peculiarities .

of colour, or transparency in the objects themselves. Many
insect, animal, and vegetable structures, though sufficiently
transparent to the eye, are absolutely opaque to the actinic
rays. I possess a specimen of a parasitic insect of a dark red
tinge, and in which a splendid internal tracheal system can
be discerned. I have tried every means of obtaining a pho-
tographic representation of this, but without success. With
all periods of exposure the object appears as a mere blank
space, or like a hole cut in a sheet of paper. Until further
discoveries have removed these difficulties, the application
of microphotography must be to some extent restricted, as
many objects are for this reason excluded. All structures
dependent upon outline or opacity, such as sections of bone
and wood, vegetable fibres, &c., may be delineated with ease
and certainty.

In conclusion, I will enumerate the peculiar advantages of
my method: first, the use of the ordinary microscope as a
solar one, a dark room serving as a substitute for a camera ;
the additional apparatus required will cost but a few shillings.
Second, the method of obtaining the combination of the che-
mical and visual foci, which I have found to be of great
practical utility ; third, the mode of obscuring for a time the
parts of the object either easily solarised and lost, or out of
focus. I have not advanced these as mere speculations, but
have submitted them successfully to the test of repeated trial.
I may also remark that when sunlight is to be obtained, I
have found the practice of microscopic photography to be one
of particular certainty, for unlike other branches, the con-
ditions of light are so favourable and definite, that an impres-
sion may always be obtained ; and though the present state of
the science in this department is admitted to be imperfect,
yet there can be no question that it is still progressive,

* Within the last few days I have succeeded in obtaining a photo-
graphic impression of the P. angulatum, magnified about fifteen thousand
diameters, showing the configuration of the markings perfectly black and
distinct in a far greater degree than we can ever hope to see them through
the compound microscope ; and it is my opinion, that if ever the structure
of these difficult tests is to be proved it will be by the aid of photography.

Rose, on Parasitic Borings in Fossil Fish-scales. 7

and in my proposals for removing some of the defects of pre-
vious methods, I venture to hope that the results may here-
after show that I have contributed my mite towards the
advancement of the art.

On the Discovery of Parasitic Borines zn Fossiz Fisu-
scaLes. By C.B. Ross, F.GS., &c.

(Read June 28th, 1854.)

THE subject of the communication which I bring before the
Microscopical Society, through the favour of my friend Pro-
fessor Quekett, is the discovery of parasitical borings within
the delicate structure of fossil fish-scales.

The history of my detection of these workings is as follows:
—In the winter of 1851, when examining fossil fish-scales
from the chalk strata of this neighbourhood, it struck me—
as many of them were thin and translucent, particularly those
of cycloid fishes—that they might make interesting micro-
scopic objects; and I sent up to Norman, in the City Road—
a well-known preparer of specimens for the microscope—a
small piece of chalk with scales adhering to it, requesting him
to put a few upon glasses for me. In consequence of their
thinness and brittle texture, he succeeded in affixing a por-
tion of two scales only. Upon examining them, I observed
that one of them exhibited elegant arborizations, extending
over a large portion of the scale; in the other scale no such
branching figures were visible; nothing, indeed, was seen
but a yellowish, translucent substance, traversed by equidis-
tant lines, evidently the lines of growth; similar lines were
also seen traversing the portion of scale containing the beau.
tiful arborizations. (See Plate L., fig. 1.)

I at first thought the ramifications were on the surface of
the scale, and imagined they might be minute coralloid bodies ;
but upon applying to them a power of 1-8th, I became satis-
fied that they were tubes of some kind within the texture of
the scale; and by varying the focus, and passing in review
different parts of the scale, I ascertained that they were situ-
ated between its lamine. Still, I could not conceive their
origin; for I was convinced they had nothing to do with the
natural structure of the scale, from there being nothing of the
kind to be seen in the other scale, and both of them cycloid
scales (Osmeroides ?).

Not very long after meeting with this interesting specimen,
I was so fortunate as to receive from Mr. Wetherell, of High-
gate, a paper, published in the ‘ Annals of Natural History,’
by Mr. Morris, of Kensington, entitled ‘ Paleontological

8 Ross, on Parasitic Borings in Fossil Fish-scales.

Notes,” in which he described, under the name of Talpina,
branching bodies, or rather the casts of branching tubes, met
with in the Belemnite from the upper chalk, adding also ex-
cellent lithographed figures of them. On the perusal of this
paper, and inspection of the illustrations, I was instantly
satisfied that the ramifying tubes I had found in the fish-
scales were of the same nature as those met with in Belem-
nites,* although the former are so much more delicate than
the latter.

The illustrations accompanying this communication will
afford you a better idea of the course and configuration of
these borings than any description which I can give; still, I
may say, that they proceed between the delicate lamine of
the scale in a graceful curve to their extremities, branching
off on either side, and terminating in a symmetrically-formed
dilatation or cell, and they do not frequently inoscolate. The
beginnings of the tubes are occasionally confluent, as seen in
fig. 1a, at c; im other instances they commence solitarily, and
the parasite, having formed a few lateral branches, has appa-
rently terminated its labours abruptly. It seems, also, that it
has sometimes passed from one lamina into another; thus
taking a transverse direction, or one perpendicular to the
lamine, which is made manifest by the microscope, now and
then detecting a transverse section of a bore. Fig. la@ ex-
hibits a detached fragment of the original specimen; viz.,
the one in which the borings were first discovered ; upon it
the lines of growth are well marked.

The discovery of the above interesting fact led me to the
examination of fossil scales from other fishes, and the next I
selected were the scales of Prionolepis angustus, a ganoid fish,
from the lower chalk. I was not long in meeting with the
depredations of its parasite; but, you will observe, on ex-
amining fig. 3, that its operations are of a very different
character to those in the osmeroid scale exhibited in fig. 1;
for, in this instance, the tubes proceed in a slightly wavy
form, with the lateral branches passing off at a consider-
able angle, and occasionally at right angles; they extend also
toa greater length than those in the first specimen ; still, there
cannot be a doubt of their having a similar origin.

Proceeding with my researches, I took another scale from
the lower chalk, of a thicker substance, therefore, possibly
from a placoid fish, but being a very imperfect specimen I
cannot say which it is, ganovd or placoid ; it is, at least, from
a different genus to Prionolepis. Here, again, I met with

* It is singular that no traces of them have been observed in the
Belemnites of the Jurassic series.—Von Hagenow.

Rose, on Parasitic Borings in Fossil Fish-scales. 9

borings, and so greatly resembling those in the last-examined
scale (fig. 3), I must, therefore, consider its parasite but a
variety of the one which infested that scale. This specimen
is represented by fig. 4; the decussating lines shown are
probably markings peculiar to that kind of scale.

Pursuing this interesting inquiry, I next took a scale found
in the shale of the Kimmeridge clay, and in it I met with
another form of the parasitic workings; for, in the first
place, they are of a larger calibre, and their form is more
decidedly dichotomous. See fig. 5. The figures given from
this scale clearly show that the parasite inhabited layers
deeper than the external one ; indeed, this circumstance was
manifest in some of my first specimens, With the view
of determining whether similar depredations are committed
upon the scales of living fishes, I have carefully examined
numerous scales of several different marine and fresh-water
fishes ; and I have not met with a vestige of borings of any
kind in a single instance.

To what form of organism, vegetable or animal, are we to
attribute these remarkable operations? We are, I am aware,
fully cognizant of the invasion of recent corals, shells, and
bones, by boring sponges (Clionz) and Conferve.* But those
intruders, although comparatively small, have their workings
in most cases visible to the unassisted eye; whereas, in the
instances which I have brought before you, most of them
require a magnifying power of 1-4th to enable us to trace
their course with any degree of distinctness. In my first
specimen (fig. 1, Plate I.), the borings of which I took great
pains to measure, I estimated their calibre at about one
2-1000th to 4-1000th of an inch.

I learn from Mr. Morris’s paper, before referred to, that
M. von Hagenow has, under the name of Talpina, “arranged
certain problematical branching bodies, which traverse the
spathose guard of the Belemnite, and whose position in the
animal kingdom has not been defined, whether as belonging
to the Annelides or to the boring-sponges.”’ From the mi-
nuteness of the agent effecting the borings within the fish-
scales, | am more disposed to attribute them to the operations
of infusorial parasites, rather than to the growth of sponges or
conferve ; particularly when I consider that the ocean de-
positing the calcareous mud must have been the habitat of
myriads of Infusoria of infinitesimal calibre. +}

* See Professor Quekett’s Lectures on the Histology of Animals, vol. ii.
pp. 42, 153, &c.

+ Since reading the above paper, I have found abundance of borings in
a scale from the mud of the river Oran, in Algeria.—C, B. R.

10 Gregory, on a remarkable Group

On a Remarkaste Groupe of Diatomaceous Forms, with
Remarks on SHAPE or OUTLINE as a@ SPECIFIC CHARACTER
an the Diatomacez. By Witittam Grecory, M.D.,

F.R.S.E., Professor of Chemistry.

(Read October 28th, 1854.)

AxourT a year ago I first noticed, in a gathering from Dud-
dingston Loch, a Navicula of nearly an oval form, with broad,
obtuse apices, which differed from all the Naviculaz known to
me. ‘The striation was peculiar and strongly marked, the
strie being about 16 in ‘001”, highly inclined everywhere,
except just about the middle, where the inclined striz seemed
to decussate, leaving, of course, a triangular space on each
side of the centre, while in these triangular spaces the striz
were parallel and transverse. This arrangement, as we shall
see, occurs in several species of Navicula and Pinnularia.

The form here alluded to was referred to different species,
and even to different genera, by different friends whom I con-
sulted ; some regarding it as a form of MNavicula semen, while
others supposed it to be related to Pinnularia gracilis, or to
P. radiosa. But its aspect was totally distinct from that of
the species named, which, moreover, all have from 24 to 26
striz in ‘O001”.

Meantime other forms occurred, with the same number
and arrangement of the striz, and with the same peculiar
aspect, but of different outline. Some were nearly rhombic,
short, and rather broad; some were longer, also nearly rhom-
bic, but with a contraction and subsequent expansion at the
apices, thus becoming more or less subcapitate. Others were
nearly linear, with obtuse ends ; others linear and subcapitate.
Some were found with nearly straight sides, and acuminate,
ending in small apiculi; while others had curved sides, con-
tracted to narrow and produced ends. In some cases these
produced ends terminated in round knobs; in others in acute
points. Some again had straight sides, with contracted ends
terminating in round heads.

In the whole of the forms now mentioned, I observed the
same characters, the same number and arrangement of the
strie, and the same aspect. On examination it appeared that
the striz were really moniliform, though not obviously so to
the éye, having rather a smooth soft aspect than any appear-
ance of granulation.

During the whole year new forms, agreeing with those
already mentioned in every point but that of outline, were
from time to time observed. In another Duddingston Loch
gathering, I found in abundance a very fine one, accompanied

by others, such as those represented in figs. 1, 18, 28, Pl. IT.

of Diatomaceous Forms. | ll

In a gathering from the vicinity of Oban I found several ;
one very near the original oval form, but with flattened apices,
and a slight tendency to constriction just within them. These
last, which closely resemble Pinnularia oblonga, shortened,
and rather broader in proportion, are frequent in a Norfolk
gathering sent me by Mr. Bleakley, in which occur also
several others.

The Oban gathering contains also various other forms of
this group, one of which has precisely the form and size of
Pinnularia acuta, and as that species occurs along with it, the
two forms are easily compared and distinguished. Here also
occur forms approaching nearly to that of Pinnularia pere-
grina, although in a purely fresh-water gathering.

In another similar gathering from a bog in Ayrshire, there
is abundance of a form not to be distinguished from P. pere-
grina, along with others of the outline of P. acuta, P. radiosa,
&e.

I now began to suspect that these forms might all belong to
one species, for on close inspection I found a very large num-
ber of intermediate or transition forms. I, therefore, named
the supposed type Navicula varians, and continued to search
for its modifications. :

In the Glenshira sand, although not very abundant, it ex-
hibits all the forms as yet enumerated, but chiefly those which
have an outline allied to that of Pinnularia gracilis, but twice
or thrice as large, and to that of P. peregrina. These forms
and several others I have since found abundantly in the recent
mud or sand deposited by the Dhu Loch, near the mouth of
the Glenshira, the lake which when at a higher level in the
valley, deposited the Glenshira sand described in the last
number of this Journal.

Having received from the Rev. Professor Smith, in Sep-
tember, a slide, of fresh-water origin, in which Navicula
varians, of the type of Pinnularia peregrina, was very abun-
dant, I begged Mr. Smith to examine the form, which he
found, as in all the other types of NV. varians which he had
seen, to have moniliform striz. He then extended the inquiry
to the typical Pinnularia peregrina, and found that it also had,
at all events in many instances, moniliform striz. From this,
I concluded, that in all probability Pinnularia peregrina was
at all times only a type of N. varians. I believe Mr. Smith
intends to change the generic name of P. peregrina to Navicula.

It seems to me in the highest degree probable, that Pinnu-
laria oblonga is nothing else than another type of UW. varians.
For the form (fig. 1) does not differ from P. oblonga, except
in length, every other detail being identical in the two forms ;

12 Grecory, on a remarkable Group

and although I cannot say that I have seen the moniliform
character of the striz either in fig. 1, or in P. oblonga, I believe
that this has been seen in the former. If so, any one who
compares the two forms which occur together, both in the
Oban gathering, and in Mr. Bleakley’s gathering from Norfolk,
will see that the latter can hardly fail to exhibit the same
character. I have not myself been able as yet to attempt the
resolution of these strize. with any refinement of appliances,
and therefore I must leave this point for future examination.

I have still to notice one more type, which I first observed
in a gathering from Lochleven, where it is very scarce, but
which is frequent in a second and distinct gathering of Mr.
Bleakley’s from Norfolk. It is rather small, and either of a
short and very broad oval form, or absolutely discoid, but has
all the characters of the group. It is seen in fig. 17. At first
I supposed it to be distinct, but I have since been led to
suspect that it is only a form of the group I have described.
This, however, is by no means certain. On the one hand,
it seems to be certainly a Navicula, although in this point of
view its orbicular form is very remarkable. It also varies to
ovals of different proportions, and it has exactly the striation
of the first observed form of WV. varians (fig. 25), to which,
indeed, in shape, the oval varieties approach very closely.
On the other hand its variations are, so far as I have yet seen,
confined within rather narrow limits ; and its form is so striking,
that I had named it at one time Navicula orbicularis. Since
the preceding sentences were written, I have been informed
that this species was some time since named by Mr. Smith
Navicula scutelloides. So far as I know, it has only occurred
as yet in the two localities I have mentioned ; namely, Norfolk
and Lochleven.

We have now mentioned most of the observed types of WV.
varians, so far, at least, as they present the characteristic stria-
tion and aspect; and although all the forms I have named
may not be found to belong to it, yet it appears that there
exists a large group, characterised by a very peculiar aspect
and striation, the number of striz varying only from about 14
in -001” in the larger to 18 in :O001” in the smaller forms,
the usual number being 16.

This group seems to include several which have been con-
sidered. as distinct species, such as Pinnularia (Navicula)
peregrina, and other forms, referred to Navicula semen, N.
rhyncocephala, Pinnularia gracilis, P. radiosa, &c., although
in these three species the normal striation is 26 in -001”.
But there are even more of the forms of this group which are
undéscribed, such as the round and oval forms ; that which

“3 ii i

of Diatomaceous Forms. 13

resembles a shortened P. oblonga; that which occurs in Dud-
dingston Loch; the subcapitate forms; the capitate forms
with straight sides; that having the form of P. acuta; and
various others.

If these two classes of forms, the known and the unde-
scribed, really constitute one group, we find in that group
nearly every shape which is seen in the genera Navicula and
Pinnularia ; and also transition forms, connecting together the
various types.

The question naturally arises: Can all these varied forms
belong to one species? Now, at one time, certainly, each
marked type of form would have been regarded as a distinct
species. But the more extended observations of recent times
have proved that form, shape, or outline, is not nearly so
permanent a character as had been imagined. In a paper on the
Mull Deposit (¢ Journal,’ January 1854,) I pointed out, and
illustrated by some figures, the remarkable tendency to variety
of form in three species, namely, Eunotia bigibba, Kitz:
Pinnularia divergens, W. Smith, and Himantidium bidens.
I alluded also to the same tendency in Eunotia triodon; and I
again returned to the same point in this last species, ina
short paper in the ‘ Journal’ for July, 1854. Other examples
are not wanting ; and the more the Diatomacez are studied,
the more do we perceive that, in many species at least, the
shape or outline is subject to endless variations. It certainly
appears at present as if, inmany species, the form were constant :
but we must be cautious in affirming this, for in two species
which I adduced as examples of constancy in outline, namely,
Navicula rhomboides, and NV. serians, we have now good reason
to believe that important variations of shape occur. Just as
NV. peregrina seems to belong to the group of NV. varians,
so it appears that WV. Crassinervia will prove to belong to N.
rhomboides ; and that a form, apparently yet more widely
differing from the latter, namely, that which I have lately
described* under the name of WN. interrupta, which is linear,
narrow and obtuse, may be found to be another modification
of IV. rhomboides. The Revd. Professor Smith has also very
recently detected a modification of NV. serians, most remarkably
different in shape from the usual type.

It will. probably be found necessary, looking to the
uniformity of markings and aspect in the forms here described,
and to the existence of such numbers of transition forms con-
necting the various types of outline, to form a species,
Navicula varians, including these forms as sub-species ; or

* In a paper read to the Microscopical Society, 25th of October last,
which will appear in the next Number of the ‘ Journal.’

14 Grecory, on a remarkable Group

else to form a subgenus, characterised by its markings,
that is, by its structure, including, as species, the chief types
of outline to be found in the group. Some system of sub-
division must be employed, in order to avoid confusion. I
dare not venture, in the present imperfectly investigated con-
dition of these forms, to prepare a permanent nomenclature
for them. I content myself with directing attention to the
subject, merely using the name JN. varians as a convenient
symbol for the group. I entertain no doubt that other
analogous groups will be detected by careful examination.

It is quite plain that in such groups form, shape, or outline
cannot be. regarded as a trustworthy specific character,
although it is probable that many species exist in which the
form, being constant, may be safely used in this way.

It is an important question how far other characters, such
as the number of the striz, or their arrangement, or the
general aspect, may be depended on as specific characters.

In this case, as in that of form, there seem to be many
examples in which the characters are constant. But yet other
cases occur where the tendency to vary seems to extend to
these characters also. Thus, I have more than once pointed
out that Pinnularia divergens, W. Smith, which, as it occurs
in the Premnay peat, has, according to W. Smith, 11 striz in
001”, occurs abundantly in the Mull deposit, and in many
recent gatherings, with every detail, and especially the very
peculiar arrangement of the striz, which have three centres of
divergence, precisely as figured in the Synopsis, while the
number of strie is from 24 to 26 in :001". I have now
repeatedly met with both varieties, and although the number
of striz seems never to fall so low as stated by Mr. Smith, yet
there is a very marked difference.

It would be out of place here to enter minutely on this
question, which, however, is well worthy of attention. It will
probably be found that in certain cases none of the characters
above alluded to are constant ; while in many they appear to
have a great degree of uniformity.

But it is strictly within the scope of this paper to notice a
group allied to that of WV. varians, and differing from it chiefly
in the number of striz.

I have already stated that some of the forms now figured
had been referred to such species as NV. semen, NV. rhyncocephala,
P. gracilis, and P. radiosa, in all of which the normal number
of striz is from 24 to 26 in ‘001."

Now, I find, occurring generally with those forms which I
refer to the group of WN. varians, others, having, like them, all
or most of the varied shapes I have alluded to, and yet having

of Diatomaceous Forms. | 15

much finer stria; in fact, agreeing in this respect with the
four species just named. To this group belong the form
figured in my paper on the Mull deposit as Pinnularia exiqua ;
that figured in the same paper as a doubtful form of P.
radiosa, or between that species and P. peregrina, and a
considerable number of other forms, which not only have the
striz inclined and otherwise arranged exactly as in NV. varians,
but pass into one another by intermediate forms, Their
aspect is quite distinct from that of MN. vartans, because the
strie, being much finer, cease to be conspicuous, as they are so
remarkably in NV. varians. To this group belongs also a form
I lately described * as WN. latiuscula, and I am inclined to.
believe that the group includes WN. semen, N. rhyncocephala,
P. gracilis, P. radiosa, and others, just as I suspect that the
group of NV. varians includes WN. peregrina and P. (qy WN ?)
oblonga. In favour of this supposition, | may mention that a
friend informs me that the striz of P. gracilis have been
found by him to be moniliform, although the fact may not yet
be thoroughly established. This, it will be observed, corres-
ponds to Mr. Smith’s observation on the strie of P. peregrina.
It is well known that the strie in P. gracilis are somewhat
obscure, and that in this, as well as in number, they differ from
those of N. varians. .But we can now see how it was that
several of the forms of WV. varians were referred to P. gracilis.
The latter, with its normal striation, appears to belong to
the second group which I have mentioned, and which,
for convenience, may be called N. mutabilis.

It will be observed that if, in the case of NV. varians, the
two characters of variableness of outline and variableness in
the number of striz should be found united, NV. varians and
N. mutabilis would then constitute but one group, divided, in
the first instance, into those with 16 striz in *001” or WN.
varians, and those with 26 strie in '001,” or N. mutadilis,
whether these divisions be regarded as species, or as subgenera.

I have only farther to add, at present, that both these
groups are widely distributed and often abundant, whether in
the shape of the known species, such as P. peregrina, P.
gracilis, &c., or in that of the types now first pointed out. I
have named those gatherings or deposits in which they occur
most abundantly ; but there are few mixed fresh-water gather-
ings in which some of them do not occur. I have it,
fortunately, in my power to supply observers with some of the
most interesting gatherings, and I shall be happy to forward
small portions of these, or slides, where the material is very
scanty, to such microscopists as may wish to examine them.

* In the paper already alluded to in a preceding nete.

DESCRIPTION OF PLATE I.

In illustration of Mr. Rose’s Paper on Parasitic Borings
in Fossil Fish-scales.

Fig.
1.—Borings in a cycloid scale (Osmeroides?), from the lower chalk of
West Norfolk.
1a magnified 35 diameters. At c¢, in this figure, is shown the
confluence of two tubes at their commencement. 1 b, a por-
tion more highly magnified.
2.—Borings in another scale, magnified 1385 diameters.

3.—Borings in a svale of Prionolepis angustus, from the lower chalk ;
magnified 135 diameters.

4.—A variety of the last, from another scale, perhaps placoid, obtained
from the lower chalk.

5.—Borings in fragments of a Fish-scale, from shales of Kimmeridge
clay.

a,a. The specimen from which these are taken has lost the
external lamina, therefore the borings lie between the two
lamin, or in an inferior one.

b,b. This specimen has the external lamina on it.

c. The external lamina is in this figure situated at d.

e

Ford & West, Imp.

Tuffen West. sc.

CUE 4)

On the DEvELopMENT of the Empryo of Purrura Lapittus,
By Writtram B. Carpenter, M.D., F.R.S., F.G.S., Presi-
dent of the Microscopical Society of London, &c. &c.

(Read December 29th, 1854.)

Nortwitustanpine the large amount of attention which has
been given by Microscopists, during the last twenty years, to
the development of the ova of Gasteropod Mollusks, and the
completeness with which, in particular cases, its successive
stages have been observed, much still remains to be learned
respecting it. And this is more especially the case with re-
gard to the Pectinibranchiate order, which includes not only a
very large proportion of the entire class, but also comprehends
those forms which, by general consent, would be regarded as
its types. For nearly all the most complete series of observa-
tions yet made, have had for their subjects either Nudibran-
chiate or Pulmonated Mollusks; the ova of the former pre-
senting peculiar facilities for examination, in virtue of their
extreme transparency, and the rapidity with which they undergo
some of their most important changes, so that these can be
watched while in actual progress ;* and those of the latter
having attracted the attention of that large class of naturalists,
who, not having the opportunity of sojourning at the coast,
are glad to avail themselves of the opportunities afforded by
the universal diffusion of Helices, Li ymnei, &c., for the prose-
cution of this kind of research.+

* On the embryonic development of Nudibranchiate and Tectibranchiate
Gasteropods, see especially the admirable memoir of Vogt, on <Actceon
viridis, in ‘ Ann. des Sci. Nat.,’ 3iéme Sér., tom. vi. (1846); also Sars,
on Tritonia, Doris, Aplysia, and olis, in ‘ Wiegmann’s Archiv.’ 1837
1840, 1845; Van Beneden, on Aplysia, in ‘ Ann. des Sci. Nat.,’ 2iéme
Sér., tom. xv. (1841); Nordmann, on Tergipes, in ‘ Ann. des Sci. Nat.,’
aime seér., tom. v. (1846) ; Allman, on Actceon, in ‘Ann. of Nat. Hist., :
vol. xvi. (1845) ; ; and Reid, on Doris, Polycera, WC.) IDFA: Of Nat.
Hist.,’ vol. xvii. (1846).

+ On the embryonic development of the Pulmonated Gasteropods, nu-
merous memoirs have been published, of which the following are the most
important :—Prevost, on Lymneeus, in ‘Ann. des Sci. Nat.,’ tom. xxx.
(1888) ; Quatrefages, on Lymneeus and Planorbis, in ‘ Ann. des Sci. Nat.,’
ziéme Sér, tom. ii. (1834) ; Laurent, on Limax and Arion, ibid., tom. iv.
(1835) ; Jacquemin, on Planorbis, ibid., tom. v. (1836); and in ‘Nova
Acta ‘Acad.,’ tom. xviii. (1838) ; Dumortier, on Lymnceus, in * Nouv.
Mém. de l’Acad. Roy. de Bruxelles,’ TOM,’ %, (1837) ; also "Ah des Sci.
Nat.,’ 2ieme Sér., tom. viii. (1837) ; Van Beneden and Windischmann,
on Limaw, in « Bull. de PAcad. Roy. de Bruxelles,’ tom. v., No. 5; also
«Amn. des Sci. Nat.,’ 2iéme Sér., tom. ix. (1888), and ‘ Miiller’s Archiv.,’
1841 ; Pouchet, on Ia ymneeus, in ‘ Ann. des Sci. Nat.,’ 2iéme Sér., tom. x.
Rathké, on Lymnceus, Planorbis, and Helix, in ‘ Froriep’ Ss neue ‘Nouken!
band may. (1842), and ‘ Wiegmann’s Archiv., 7 1848 ; Fred. Muller, on
Helix, in ‘ Wiegmann’s Archiv.,’ 1848; and Gegenbaur, on Lelia, &e.,
‘Siebold and Killiker’s Zeitschrift,’ 1852.

VOL. III. G

18 Dr. Carrenter, on the Development of

The only detailed observations with which I am acquainted,*
that have been made upon the embryonic development of
Pectinibranchiate Gasteropods, are those of MM. Koren and
Danielssen on Buccinum undatum and Purpura lapillus ;} and
these disclosed phenomena of so extraordinary a character,
that, if their facts and inferences are to be implicitly received,
many of the general doctrines of development which had been
considered to be most surely established, would need to be
greatly modified in their application to these animals, as pro-
bably to their congeners also.

The singular circumstance was long since noticed by Dr.
J. E. Gray,t that a capsule of Buccinum enclosing more than
a hundred ova, yielded only four or five mature embryos; and
it was supposed by him that, as often happens in Plants, the
great increase of some ova hinders the development, and ulti-
mately effects the destruction, of the remainder. ‘The condi-
tions under which development takes place in the two cases,
however, are so essentially different, that no parallel can be
reasonably drawn between them. Ps

A similar order of facts is presented by Purpura. Each
capsule originally contains several hundred bodies,§ having
the appearance of ova (Plate III., fig. 1); yet when it is opened at
an advanced period, no more than from twelve to forty embryos
are found in it ; these, however, being of such large dimensions
(Plate III., ae 15, 16), that their aggregate mass equals
that of the far more numerous bodies which they replace.
In what manner, then, are the materials of the abortive
ova (?) applied to the nutrition of the embryos, whose

* The Memoir of Leydig on Paludina vivipara (‘ Zeitschrift fiir wissen-
schaftliche Zoologie,’ 1850), referred-to by MM. Koren and Danielssen,
has not fallen in my way.

+ ‘ Bitrag til Pectinibranchiernes Udviklingshistorie, Bergen, 1851 ;
translated in ‘ Ann. des Sci. Nat.,’ 3ieme Sér., tom. xviii. xix. (1852-3),
and in ‘ Taylor’s Scientific Memoirs,’ 18538.

t+ ‘Loudon’s Magazine of Natural History,’ May, 1837.

§ In both the translations of MM. Koren and Danielssen’s Memoir,
these observers are made to state the number of these bodies as sixty or
more. But it is evident, from the accounts which they subsequently give,
of the coalescence of these bodies into embryos,—‘“‘ some embryos resulting
from the union of three or four ova, while sixty or more had contributed
to form most of the others,”—that this number is understated. As it is
expressed in figures, I think it probable that a O has been accidentally
omitted, and that the number should have been 600. This would cor-
respond well with the average of my own estimates. The number is by
no means constant, however; the capsules varying much in size. Those
of the same cluster, deposited by one individual, usually correspond with
each other pretty closely ; but the ratio of capacity of those in different
clusters is occasionally at least 2: 1; and this partly accounts for the
difference in the number of mature embryos noticed above.

the Embryo of Purpura lapillus. 19

increase and development thus seem to take place at their
expense ?

This is the problem to which MM. Koren and Danielssen
applied themselves, and of which their solution presents phy-
siological difficulties scarcely inferior to those of the problem
itself. Their account of the process is briefly as follows :—
Each of the numerous bodies originally aggregated in the
ovigerous capsules, is regarded by them as a true ovum; of
which the vitellus undergoes a cleavage, which is at first
regular, but subsequently irregular, dividing it into from six
or seven, to sixteen or eighteen cleavage-segments. These
segments then agglomerate into a compact mass, in which,
however, the clusters formed by the separate ova may be dis-
tinguished for some time. Ata later period, they describe this
conglomerate as presenting manifest subdivisions, which
become more sharply circumscribed, and project from the
remainder of the mass. ‘‘ These projecting groups soon take
a cylindrical or pyriform shape, and are fixed to the rest by
means of a peduncle. The microscope shows them to be
composed of a delicate ciliated membrane, enclosing a mass
of ova; a transparent substance exudes from the two sides of
the peduncle, upon which fine cilia appear (the foot) ; and at
the base of this same peduncle, the first traces of the lobes
are distinguishable. Finally, many of these pyriform bodies
become detached from the mass, and rotate upon themselves ;
these are the embryos.” ‘Thus, according to these observers,
a number of ova, varying from three or four to sixty or more,
coalesce to form each perfect embryo.

But they have also observed another phenomenon, which
they consider as altogether abnormal; namely, the develop-
ment of an embryo from a single ovum, which does not become
fused into the conglomerate mass. Such an embryo, they say,
is always to be found in each capsule, up to the eighth week
of its development; and it is at once known from the rest, not
only by its small size, but by the very imperfect development
of its organs, the ciliated lobes and foot being the parts first
and most completely evolved, and the other organs being
nearly or entirely abortive; this inequality giving a strange
and (at first sight) almost incomprehensible appearance to the
‘monster.’ Hence, then, they conclude that * for the viability
of the individual organized, more than one ovum is necessary ;
and despite the regularity and the vivacity observable in the
young product of the single ovum, we see that its development
remains in the highest degree incomplete. This single ovum
had in fact undergone all the stages of cleavage, and to all ap-
pearance united all the anatomical and physiological conditions

c

20 Dr. Carpenter, on the Development of

necessary to its complete development; while, on the other
hand, it appears to us to be incontestable that it had never
been in possession of the materials requisite for the formation
of organs.”

Having had the opportunity, during a short sojourn at
Tenby in August and September 1854, of applying myself to
this investigation, I gladly availed myself of it; for the pur-
pose of affording to the statements and conclusions of MM.
Koren and Danielssen, should I find them borne out by facts,
that confirmatory testimony from an independent observer,
which their aberrant nature seemed to require; or, on the
other hand, to correct them, if I should find them to be in
error. I can honestly say that I entered upon the investiga-
tion without prejudice of any kind; for whilst, on the one
hand, there appeared to be a strong antecedent improbability
about their view of the case, yet, on the other, so many won-
derful truths have been elicited by modern research,*—“ so
various’ (as my friend Mr. Huxley has well phrased it) “‘are
the possibilities of nature,”—that its very strangeness had
almost something to recommend it.

The general result of my observations is, that the process
has been altogether misconceived by my predecessors ; that no
such departure from the ordinary plan of development takes
place, as the fusion of a number of originally distinct ova into
a single embryo; but that each embryo originates in a single
ovum ; that it attains toa certain grade of development by the
metamorphosis of the contents of its own vitellus; but that its
increase in size, and the continuance of its development, depend
upon its appropriation, by a process of deglutition or swallow-
ing, of a mass of additional or supplementary vitellus, the want
or insufficiency of which occasions its partial or complete
abortion. As to the immediate cause of the production of
‘monstrous’ embryos, therefore,—a phenomenon which I have
found to be far more common than MM. Koren and
Danielssen supposed,—I am in accordance with my predeces-
sors, as I attribute it, with them, to the deficiency of nutritive
material. But I differ from them essentially, not merely in
regard to the mode in which this nutritive material is appro-
priated ; but also in asserting that the production of embryos
from single ova, instead of being an abnormal and occasional

* What, for example, could have been more improbable, @ priori, than
the detachment of the arm of the male Argonaut, and its continued exist-
ence as (in some sort) an independent self-moving being, so as to have
been mistaken for a Worm, in order to serve as the instrument for the
fecundation of the female ?

the Embryo of Purpura lapillus. | 21

phenomenon, is one stage in the normal process of develop-
ment.

Notwithstanding my own conviction of the truth of my
conclusions,— based upon the careful and repeated observation
of certain most important phenomena in the history, which
have been altogether overlooked or very imperfectly seen by
my predecessors, whose ignorance of these facts has vitiated
the whole of their interpretation of the process,—I might have
hesitated in thus giving a somewhat confident expression to
them, since the limitation of my time prevented me from
working-out the investigation with the completeness I should
have desired. But during my prosecution of the inquiry, I
had the advantage of being able to satisfy my friends, Mr. G.
Busk and Mr. T. H. Huxley, of all those facts on which my
conclusions are based; and the former of these distinguished
naturalists and excellent observers, having remained at Tenby
for some time longer than myself, not only verified these by
his own independent observations, but also supplied some ad-
ditional facts of great value in regard to the earlier stages of
the process, which he has kindly allowed me to incorporate in
the history which I shall now offer. I cannot but believe,
therefore, that the joint testimony of my friends and myself,
as to what we have ourselves repeatedly witnessed, should re-
move all reasonable doubt about the facts of the case; and the
inferences from these facts seem inevitable.

Each of the flask-shaped ovigerous capsules of the Purpura
lapillus contains a large number of egg-like bodies (usually
from 500 to 600), in the midst of a pellucid viscous liquid,
very like ordinary white-of-egg. (Plate III., fig. 1). These
do not at first present any feature of dissimilarity, one from
another. 'They are all spherical, or nearly so, in form ; and
their diameter is pretty uniformly ‘0075 of an inch. Not-
withstanding the statement of MM. Koren and Danielssen,
that they have ‘a delicate chorion and a vitelline membrane,”
I have not been able to detect any appearance distinctly indi-
cating the presence of a membranous investment around them.
When crushed, they are found to be composed of vitelline
matter, consisting of ovoidal particles strongly resembling
starch-granules (fig. 2.) in size, form, and general appearance,
but of albuminous composition, imbedded in a fluid loaded
with minute granular particles, many of which seem to be
oleaginous. I have not detected in any of them, either a
germinal vesicle, or any body which could be considered as
representing it; but I have occasionally met with what ap-
peared to be the void space, which the germinal vesicle might
have formerly occupied. Having, for the sake of comparison,

22 Dr. Carpenter, on the Development of

examined the unfertilized ova still contained in the ovary, but
approaching maturity, I found them to correspond in size and
appearance with the bodies which fill the ovigerous capsules,
but to possess the usual germinal vesicle and germinal spot.

As it will appear, from the details to be presently given,
that some of these bodies are true ova, whilst others are merely
yolk-segments, it comes to be a question of much interest,
whether the former can be distinguished from the latter, at
this early period of their history. Neither Mr. Busk nor my-
self, however, has been able to detect any marked difference,
previously to the occurrence of the first segmentation.

In the course of a few days, all the egg-like bodies in the
capsule begin to show signs of cleavage. In the greater part
of them, the two segments produced by the first cleavage are
equal, or nearly so; and each of these again subdivides into
other two which are alike equal. The subsequent cleavages
take place with less regularity, so that the mass often lack its
symmetry of form; but they commonly issue in the sub-
division of the whole vitellus into from about twelve to eigh~
teen segments, whose diameter averages ‘(030 of an inch
(Plate UI., fig. 5, a, b, c, d).

Here and there, however, we may distinguish among the
rest, one of these egg-like bodies whose cleavage divides it
into two segments whose inequality is very marked (Plate III.,
fig. 6, a); and at one end of the line of constriction, there are
to be seen one or two, or perhaps three, minute vesicles, near
which is a clear space in each segment, These are obviously
the ‘ Richtungs-blaschen,’ or Vesicule directrices, which were
first observed by Carus, afterwards by Dumortier, Pouchet,
Sars, Van Beneden, and Reid, and more recently by Fred.
Muller (who ascribes to them a great importance in the primi-
tive dese lap meneiuaNee? of the ovum), by H. Rathké, and by

Gegenbauer.* These vesicles were noticed by Koren and

* It is not only in the ova of Gasteropods, that these vesicles present them -
selves. They had been seen in the ova of several Lamellibranchiata, Annelida,
and Entozoa; and in several Vertebrata also. See the Third Series of
‘ Researches on Embryology ’ (‘ Philosophical Transactions,’ 1840), by Dr.
Barry, who repeatedly figured these vesicles, but quite misapprehended
their import; the Memoirs of Professor Bischoff, on the ‘ Embryonic De-
velopment of the Dog, Rabbit, and Guinea-pig ;? and the posthumous
Memoir of Mr. Newport, ‘ On ‘the Impregnation of the Ovum, and the
Growth of the Embryo in the Frog,’ in the ‘ Philosophical Transactions,’
1854, p. 284 et seg. With reference to the idea of F. Muller, that these
spherical bodies determine the line of first cleavage of the yolk, Mr. New-
port remarks :—‘* My observations on the development of the embryo lead
me to believe that, though the transit of these bodies is usually in the
same line as the first cleft, the direction of the fissure is not determined
by them, but is owing to some other cause.”

the Embryo of Purpura lapillus. 23

Danielssen in the ovum of Buccinum; and in a supplement
to their former researches, they confirm the statement of pre-
vious observers, that in the youngest ova they exist in the in-
terior of the egg, and pass from thence to the surface. ‘They
distinctly state, however, that they could not find them in the
ova of Purpura, although they took great pains to look for them.
There frequently appears to be but one (Plate IIL, fig. 3) ; but
this is probably because the second vesicle is behind the first.
When both come into view, one vesicle is almost invariably
observed to be smaller than the other (Plate III., fig. 4). It is
comparatively rare for three to present themselves. The
vesicles are very pellucid; the larger one is filled with a fine
granular material, and apparently unfurnished with a nucleus ;
the smaller is a nucleated cell, and is more transparent. The
vesicles are invariably found on that side of the ovum, at
which the head and other appendages are formed ; never at its
posterior part. ‘Their gradual separation from the yolk-mass,
to which they seem to be connected by a kind of viscid mucus,
clearly shows that this is not enclosed by any vitelline mem-
brane.*

The difference between the two kinds of bodies, at first in-
distinguishable from each other, now becomes apparent; the
former are nothing else than vitelline spheres (as was suspected
by M. Milne Edwards in the case of Buccinum), ft whilst the
latter are true ova. ‘The subsequent destination of the two
respectively makes this very obvious.

Shortly after the completion of the subdivision of the
‘vitelline spheres’ into clusters of ‘ yolk-segments, the whole
ageregate of these shows a tendency to mutual coalescence.
Up to that time, these clusters have remained distinct from
each other, and are always separated by the intervening viscid
liquid ; and even if flattened against one another by pressure,
they separate again on the removal of that pressure, without
the least appearance of mutual fusion. But at this period they
adhere with considerable tenacity, so that it is difficult to tear
apart the aggregate vitellus into its component clusters of
yolk-segments (Plate IV., fig. 7) ; and this coalescence speedily
becomes so complete, through the mutual adhesion of the
yolk-segments themselves, that the form and demarcation of
the clusters are obscured and finally lost; the resultant being
a conglomerate mass of yolk-segments (Plate III., fig. 10);

* For the knowledge of the facts stated in this paragraph, I am indebted
to Mr. G. Busk. I had myself frequently noticed the presence of the
vesicles in the course of my examinations of the contents of the capsule
at this stage; but I was not then aware of their significance.

+ ‘Ann. des Sci. Nat.,’ tom. xviil., p. 261, note.

24 Dr. Carrenter, on the Development of

having no definite form, and nearly filling the ovigerous
capsule.*

I am not able to detail, as fully as I could wish, the mode
in which the segmentation proceeds in the true ova, and in
which the proper embryonic structures first appear; but as far
as I have been able to gather from my own observations and
those of Mr. Busk, the subdivision of the smaller of the two
primary segments (which I shall call the anterior) takes place,
until a collection of very minute spheres is formed along one
margin of the larger or posterior segment which has undergone
no subdivision (Plate III., fig. 6, 4,¢). This portion then
becomes pellucid, and is obviously bordered by a membrane
(fig. 8, a); and gradually a pellucid margin is seen to present
itself around the whole vitellus (fig. 8, a, b, c), the border,
however, being still much broader at the anterior part than at
any other. ‘The pellucid membrane soon becomes clothed
with very delicate cilia; and these are particularly abundant
at its anterior extremity, where an important change speedily
takes place. ‘The broad margin extends itself on either side, so
as to form the rudiments of the two ciliated lobes which seem
to belong to the early embryos of all Gasteropods (fig. 8, c) ;
whilst between these, the transparent envelope seems to thin-
away (?), until an aperture is formed, leading directly down to
the cavity wherein the vitellus lies (fig. 8, d). This aperture
elongates into a canal, the whoie interior of which, as well as
its margin, is thickly clothed with cilia (fig. 9, a, 6). Thus
the larval Purpura becomes possessed, by such a process of
transformation as takes place in the embryo Polyzoon, of a
mouth with ciliated lobes on either side, a ciliated cesophagus,
anda gastric cavity ; which, although at first fully occupied by
the original vitellus, soon shows a capacity for more, the walls
of the cavity itself being enlarged by material withdrawn from
the vitellus, and the space occupied by the latter being cor-
respondingly reduced by the appropriation.

This process is going-on at the same time with the segmen-
tation and coalescence of the vitelline spheres. But there
is no such relation between them, as binds them to an
exact synchronism. [For I have sometimes met with a
dozen or more of embryos, developed up to the cesophageal
stage, in a capsule whose vitelline spheres had not yet begun

* Notwithstanding the most careful examination, I must confess myself
unable to discover in the conglomerate mass, still less in the bodies of the
embryos which are formed at its expense, those distinct indications of the
original clusters, which are represented by MM. Koren and Danielssen
in their figs. 27-31; and since the vitellus is swallowed by the embryo
(p. 25), particle by particle, it is impossible that any such grouping can
be preserved within their bodies.

the Embryo of Purpura lapillus. ; 25

to coalesce; whilst, on the other hand, I have found the
coalescence to have completely taken place, without any sign
of more advanced embryonic development, than the presence
of the clear margin around some of the vitelline bodies im-
bedded in the aggregate mass. Generally speaking, however,
I believe that by the epoch of complete coalescence of the
vitelline spheres, some of the embryos will have attained the
cesophageal stage, and will be found external to the conglomerate
mass, as shown in Plate IV., fig. 7, 6, c, d,e, fg 3 whilst others,
a, not yet so far advanced, are imbedded in its superficial por-
tion, and are consequently only to be found by careful search.
‘That as many of these original embryos as usually come to
maturity, are to be found in some stage of development or
other, in every capsule whose vitelline segments have coalesced,
except in such as are destined to failure from the want of
them,* I am satisfied, from the unequivocal evidence afforded
by repeated observation. |

The embryos which have attained the stage of development
just described, attach themselves by the mouth to the con-
glomerate yolk-mass (Plate IIL, fig. 10) ; and by the continued
action of their ciliary apparatus the particles of this mass are
detached, and are driven down their cesophagus into the gas-
tric cavity, which is gradually distended by them, until the
embryo attains many times its original size. This statement
is not a mere inference, resting on the fact that embryos of
various sizes are often found attached to the same yolk-mass
(Plate IV., fig. 11, a4, b,c, d, e, f); for under favourable cir-
cumstances I have been able to witness the detachment and
ingestion of the particles, and to observe a sensible enlarge-
ment of the embryo in consequence. This, however, is not
often possible, since the entrance into the cesophagus is gene-
rally overlapped by the conglomerate yolk-mass on one side
or the other, so that it cannot be seen-through. On one occa-
sion, however, I witnessed a very curious occurrence, which
afforded a remarkably satisfactory view of the process.
Having opened a capsule, of which the contained embryos
had almost entirely appropriated the yolk-mass, and had con-
sequently attained to nearly their full size, I observed one

* The number of true ova bears no relation whatever (as will hereafter
appear) to that of the vitelline spheres. Sometimes there are not enough
of the latter for the full development of the embryos ; sometimes, on the
other hand, there are more than are required. And I have found so many
capsules in which the vitellus was undergoing decomposition, apparently
for want of embryos to appropriate it, interspersed among those which
contained the usual number of embryos in full course of development,
that I am satisfied that the want of true ova is not a very unfrequent
occurrence.

26 Dr. Carrenter, on the Development of

of them with a peduncular elongation still projecting from
its mouth, as seen at fig. 13,@ (an appearance which is not at
all unfrequent, and which is often due, I believe, to the de-
tachment of the embryo by the rupture of its peduncle, in the
very act of opening the capsule) ; it happened that another
and somewhat larger embryo was swimming near, and the
currents produced by the ciliary action of both drew their
anterior extremities together, in such a manner that the
peduncle of vitellus protruding from the mouth of the one
inserted itself into the mouth of the other, and the two re-
mained for some time in this close relation, notwithstanding
that I purposely agitated the water in the trough that con-
tained them, in a manner that would have caused the separa-
tion of bodies in mere juxtaposition. It seemed that the
ciliary action of the larger embryo was more powerful than
that of the other; for I could distinctly perceive, through its
transparent neck, the detachment of particles belonging to the
projecting peduncle of the other, and their passage down its
own cesophagus ; and whilst the size of the larger did not
much exceed that of the smaller when they first came into
mutual proximity, the former, in the course of a couple of
hours, had appropriated so much of what belonged to the
latter, that their comparative dimensions became more nearly
as three to two.

Though I have spoken of distention of the gastric cavity by
the new vitellus thus strangely introduced, I do not mean to
affirm that its enlargement is solely due to such distention
from within. On the contrary, | have met with obvious evi-
dence that the cavity enlarges to receive it, by the growth of
its own walls; for it sometimes happens that this enlargement
takes place faster than the new vitellus is introduced, so that a
void space is left. Generally speaking, however, there is an
actual distention of the walls of the gastric cavity of the
embryo, and this may proceed to such a degree as to involve
the ciliated lobes also; and thus all traces of the original
form may be lost, and nothing apparently remain but an
ovoidal body, covered with a ciliated membrane, and attached
by a peduncle to the conglomerate mass (fig. 13, ¢). If this
form only was seen by MM. Koren and Danielssen, I am not
surprised that they should have imagined it to be a pedun-
cular segment of the vitelline mass. But having traced the
embryo through every stage, from its first appearance as an
embryo, to that which it here presents, I feel perfectly satis-
fied that the bodies in question are genuine embryos, in the
act of appropriating the supplemental yolk; and that their
variety of size merely results from the difference in the amounts

—

the Embryo of Purpura lapiilus. | 7 |

which they have respectively ingested. In some capsules |
have found all the embryos to present nearly the same bulk ;
whilst in others, I have met-with nearly full-sized embryos
attached to the same conglomerate vitellus, together with
embryos which had made but little advance upon their original
dimensions.

Another fact of no small importance, in reference to my
view of the case, is that on crushing one of the pedunculated
embryos, | have almost invariably found the small original
vitelline mass in the interior of the large supplemental yolk ;
the original vitellus being readily distinguished by its lighter
hue, and by a very definite boundary line, although I could
not find any evidence of a membranous separation. And
again, in several embryos which had only ingested a very
small allowance of the supplemental vitellus, this was seen
not to envelop the original mass, but to remain superposed
upon it (Plate IV., fig. 17).

During the time in which they are thus appropriating the
additional supply of nutriment which is required for their
complete evolution, the embryos make very little advance in
the development of new parts. This process soon recommences,
however, and is then carried-on vigorously at the expense of
the new material introduced. The ciliated lobes are much
enlarged, and acquire those peculiarly long cilia, which have
been distinguished as cirrhi; the foot is evolved, and covered
with short cilia; the auditory vesicles soon show themselves
at its base ; the tentacula and eyes make their appearance ;
and in the mean time the mantle and shell are being formed
at the posterior part of the body. Now this developmental
process may be arrested in any stage, for want of sufficient
nutriment; and thus we may not only meet with advanced
embryos much smaller than the average size, in the same
capsule with others of the usual dimensions, but may often
find in the same capsule not only one embryo, but several
embryos, in various stages of abortive evolution. The
original vitellus, when it receives no addition from the con-
glomerate mass, seems to be entirely exhausted by the de-
velopment of the ciliated lobes, which attain nearly their full
size, notwithstanding that the body behind them is no larger
than at first, or may even have shrunk in consequence of the
withdrawal of its contents ; so that such a ‘ monster’ would
not be recognized as having any relationship to the ordinary
embryo, but for the intermediate forms which are frequently
to be met-with. I have even seen the auditory vesicles in one
of these abortive embryos, which showed no sign of having
received any additional vitelline material. But for the de-

28 Dr. Carpenter, on the Development of

velopment of even the rudiment of the foot, I am satisfied that
some further supply is a necessary condition; and still more
is needed for the development of the tentacula and eyes. It
is very curious to see embryos that have attained this stage of
evolution, entirely destitute of the means of developing any
of the visceral apparatus ; this being formed at a later stage,
and by the conversion of the large mass of conglomerate
vitellus which has been intreduced into the gastric cavity.
And it is not less curious, that these abortive embryos should
continue to live so long, being often observed swimming
actively about, when the Sorel embryos have attained almost
their full intra-capsular development.

Although it is very common to meet with one or two of
these abortive embryos among the twelve or twenty normal
embryos, which are ordinarily contained within the capsule,—
and although we may then attribute their abortion to some
accidental interference with the process by which they should
have attached themselves to the conglomerate mass, and have
appropriated a part of its materials,—yet when, as sometimes
happens, a large number of aborted embryos are found within
one capsule, their abortion may be probably attributed to a
deficiency in the store of food provided for them. Thus in
one capsule I have found twelve nearly-mature, full-sized, and
perfect embryos, twelve others decidedly under-sized, but still
having all the organs complete which belonged to their period
of development, and twelve embryos in various stages of
abortion. ‘The capsule contained no unappropriated yolk ;
and the deficient size of some of the embryos, and the abortion
of others, seem fairly attributable, therefore, to the imequality
between the “supply” of nutriment, and the ‘demand ” set
up by so unusual a number of embryos.

On the other hand it is not at all uncommon to find, in a
capsule which contains an unusually-small number of em-
bryos, a portion of the yolk-mass unappropriated, even when
the embryos have nearly reached their full development. ‘The
embryos, when few in number, are commonly of unusually
large dimensions ; thus in fig. 14 (Plate 1V.) is shown such
an embryo, gorged (as it were) with vitelline spherules, and
having a residual mass of these, still unappropriated, remain-
ing attached to its anterior extremity.

I have not attempted to follow any part of the history of
development into its details; the whole of my time and atten-
tion having been devoted to the solution of the one problem
which I originally set myself to investigate; and the limita-
tion of my opportunity for observation having obliged me to

the Embryo of Purpura lapillus. | 29

content myself for the present with having obtained what |
hope will be deemed a satisfactory elucidation of it. I may
mention, however, as points which require far more careful
examination, the mode in which the first segmentation takes
place in the true ova, and, more especially, the mode in which
the primary mouth and cesophagus are formed. I am not at
all sure whether this is effected by the thinning-away of the
peripheral membrane, so as to form an entrance to the inte-
rior; or whether, as some appearances I have seen in later
embryos would suggest (Plate IV., fig 13, a, 6), the cavity
which receives the additional vitellus is formed by the infold-
ing of the peripheral membrane. ‘The relation of the original
mouth and esophagus to the permanent organs of like kind,
constitutes another very important subject of investigation,
which becomes very difficult through the obscuration of these
parts at a later period by the ciliated lobes, foot, &c. In re-
gard to the history of later stages, also, Iam satisfied that
although Messrs. Koren and Danielssen haye made out many
important particulars, they have at the same time committed
mistakes scarcely less serious than those which | have already
had occasion to correct. For example, the curious contractile
vesicle which they have described as the heart, is certainly
not the real heart; as this is not formed until some time after
the contractile vesicle, and is situated deeper within the
cavity of the mantle; and the two may, under favourable
circumstances, be seen pulsating simultaneously but not syn-
chronously.

It now only remains to inquire, whether any phenomenon,
at all parallel to that which I have described, presents itself
elsewhere in the animal kingdom. Sema bane like it appears
to take place, according to the statement a Siebold, in the
case of the embryos of Planariz ; for he says of them, * that
after they have a covering of ciliated epithelium, “ they do
not increase as before by the external fusion of cells; but
there is a muscular, discoid, cesophagus formed upon their
periphery, through which the remaining cells are ingested
and assimilated within the animal.” It is very probable that
many similar cases will be discovered, when the process shall
have been adequately looked-for, In particular it may be
expected to present itself among the Gasteropod Mollusca,
since the enlargement of certain embryos at the expense of
the other contents of their capsules appears to be a common
phenomenon among them.

* Vergleichende Anatomie, § 129.
+ It seems reasonable to suppose, from the account given by Messrs.

30 On the Embryo of Purpura lapillus.

But I think that we may reasonably question whether the
process, anomalous as it seems, is really anything else than a
variation of the mode of introducing into the body of the
embryo that separate store of ‘ food-volk,” which many of
the higher forms of animals require as a necessary addition
for the completion of their embryonic development, that has
been at first carried on at the expense of the “ germ-yolk.”
Thus in the early development of the chick, the cicatricula or
germ, formed (as appears probable) by the cleavage of the
germ-yolk, sends off a membranous expansion, which extends
itself by marginal growth, until it spreads itself around the
food-yolk, which it thus encloses in what may be termed the
temporary stomach of the embryo. And it seems to me that
there is an essential parallelism between the condition of the
embryo-chick at this stage, and that of the embryo-purpura
when it has distended its body with yolk-segments which it
has detached from the conglomerate mass, and has conveyed
into its own visceral cavity. |

The only difficulty that occurs to me, in regarding the great
mass of the contents of the capsules as yolk-segments, arises
from the fact of their undergoing a subdivision like that of
fertilized ova. But this subdivision has very definite limits ;
it never tends, like the subdivision of the yolk of the true
embryos, to a “ differentiation” of parts; and seems to be a
mere ‘ fractionnement,” designed to break up each body into
smaller spherules.

Koren and Danielssen of the development of Buccinum, that they have
made a like error of interpretation to that which they have committed in
the case of Purpura; of this Professor Milne-lidwards has already ex-
pressed his suspicion. See ‘ Ann. des Sci. Nat.,’ 3iéme Sér., tom. xviii.,
p. 261.

Observations on Cosmartum MarGaARITIFERUM and other Des-
MIDE#. By Mrs. Hersert Tuomas, Bristol, Communi-
cated by Dr. CarPENTER.

(Read January 24th, 1855.)

In the month of February, 1851, while watching, for the first
time, in the Zygnema, the curious phenomenon of conjugation,
my attention was attracted by a beautiful object passing with
a slow, unsteady motion over the field of the microscope; at
the same time I observed that in its interior small granules
were moving with extreme rapidity, resembling a swarm of
bees more than any other object to which I can compare it.
This plant I afterwards knew to be Cosmarium margaritife-
rum. From that period I have made this plant the object of
my constant observation, and have at the time recorded by
delineation anything which struck me as new, without, how-
ever, endeavouring to draw conclusions from my observations,
which, from my imperfect microscopic knowledge, I knew
might too often prove incorrect.

The plant, as I first saw it in February 1851, is figured at
Plate V., fig. 3. In each half, the centre was occupied by a
vesicle (as it appeared) filled with moving granules, while
smaller vesicles were at the four sides. The granules did not
appear to circulate through the plant, but kept to their own
place, which was either a bag or cavity, [ could not decide
which. In fig. 1, subsequently drawn, I have recorded that
the granules were swarming over the whole plant. This may
possibly have been due to alteration of focus, bringing the
larger granules more prominently into sight; or it may have
arisen from some difference in the early growth of the plant,
as the specimens represented in figs. 8 and 9 showed corre-
sponding differences, fig. 8 developing into fig. 1, fig. 9
into fig. 3. °

I now carefully preserved the water in which my Cosma-
rium was tolerably abundant; and by continually changing
it, kept the plants healthy. From my recollection of certain
hoses which I have since occasionally seen, I think that con-
jugation may have taken place during the summer; but I was
not then acquainted with the sporangia of the Desmidie.
As the summer advanced, many of the plants lost their spring
beauty and active motion ; fig. 10 represents the appearance
of some; in others the inner membrane was very much shrunk,
containing only a little of the green matter, or if in active
life, the colours assumed more of an autumn aspect, probably
from the colour of the light thrown upon them. In fig. 6

VOL. 111. d

34 Observations on Cosmarium Margaritiferum.

the contents of the inner bag had so much distended them-
selves, that the bead-like margin of the outer case was lost.*
In this figure I have represented as accurately as possible,
the appearance presented on November 12th. On this plant
I noted—“ The motion very active, and the plant apparently
in a healthy condition. The outer membrane quite plain,
but certainly the same plant as the others. When fresh
water was introduced around the object, the outer membrane
remained immoveable, while the inner was pushed into a
globe. The granules escaped one night, and the plant as-
sumed much the appearance of fig. 10.” In the following
spring I figured fig. 5, which appeared to me early develop-
ment of the masses of swarming granules; and fig. 2,
which, in the same month (February 1852), was the most
usual appearance and colour, becoming darker and fuller as
the spring advanced. In the summer of 1851, I applied
iodine to fig. 3, when the granules ran with extreme rapidity —
into four balls, as represented in fig. 7; I also tried to find
out their nature by pressing them out of the plant. In this I
was unsuccessful, as the contents mingled rapidly with ‘the
other vegetable forms in the water. I satisfied myself, how-
ever, that they escaped at the centre of the plant, from which
part the contents escape to form the sporangia, as I afterwards
discovered. As I frequently found plants resembling fig. 4,
I concluded that when the plant was mature the granules
escaped of themselves. | ;

In September 1851, I had the pleasure of observing ano-
ther change in these beautiful plants. At one o’clock the
two hemispheres of a plant separated, as figured in fig. 11;
the transparent hemispheres protruded between the original
halves, containing only colourless granules. At six o’clock,
the four parts were nearly equal in size, and the green matter
evenly divided, though faint in colour. At eleven next
morning, the whole had assumed a healthy, vigorous appear-
ance, as at fig. 12. Soon after, a restless motion was visible ;
and at twelve o'clock the plants were freeing themselves from
an enclosing membrane (13), which had first appeared in
fig. 11. At one o’clock the plants had escaped, and moved
freely off into the surrounding water, leaving their old enve-
lopes, which, in the following spring (1852), when my plants
were very healthy and active, I found in great numbers in the
water. I suppose that the time taken on this occasion (twenty-

* This observation is an important one, if it be quite sure that the
specimen observed was C. margaritiferum : it may be questioned, how-
ever, whether it was not a specimen of C. Ralfsii, which had found its
way amidst the others.—W. B.C. |

Observations on Cosmarium Margaritiferum. 35

four hours) might be about an average time required for sub-
division; but the period required for the ripening of the
moving granules, I cannot in the least calculate. I took a
plant in apparently full maturity, and watched it for a fort-
night; but I could trace no change in its appearance, nor did
the granules weary in their motion, either in sunlight or in
shade, in daytime or at night; for in the dead of night, when
hours of darkness might have brought on them the “ sleep of
plants,’ I suddenly threw upon them a strong light, and
found them in their usual activity of motion, while the same
light only gradually and partially roused a ‘ wheeler” from
his slumbers.. I have figured four monstrosities in subdi-
vision, which I observed in the spring of 1852 (figs. 15, 16,
17, 18). I was much inclined in 1851 to suppose, from the
figure fig. 21, that subdivision took place at various ages of
the plant; I subsequently found, however, that this must
have been a plant of C. Thwaztsi7, which I obtained in the
spring of 1852, in a neighbouring locality, in great activity of
division and swarming motion; and in the same autumn I
found sporangia of two species, which would lead me to sup-
pose fig. 22.a full-grown form. (See figs. 25 and 28.)

All the species of Cosmarium do not appear to have the
habit of casting off their envelopes; for in fig. 19, which I
found in great abundance, both subdividing and forming
sporangia, no loose vesicles were left from the former process,
though in the latter the empty cases were abundant and per-
manent. Being greatly disappointed at not being able to
prove the use of the moving granules, I watched as minutely
as I could the formation and subsequent development of the
sporangia, The contents of the ball, as in the division of the
plant, were at first light in colour, and containing few gran-
ules; they subsequently became darker green, and then a
reddish-brown, as in figs. 25, 26, 27, or as in figs. 23, 24;
and at the same time the coats became more numerous.

In the month of April 1853, I was delighted to find in the
bottle containing the sporangia of Cosmarium, fig. 24, a
many-coated ball filled with granules in the same rapid
motion as observed in the full-grown Cosmarium. The simi-
larity of the movement attracted my attention; and I also
saw that in one part the enclosing membrane appeared thinner,
as if giving way at that spot. On the third morning the
membrane had broken, and the granules escaped, leaving the
nearly-emptied case as represented at fig. 29. See alsv
fig. 30.

I will now speak of the changes visible to the naked eye,
while preserving in bottles water in which Cosmarium margari-

d 2

36 Observations on Cosmarium Margaritiferum.

tiferum and others of the same family were very numerous.
During the summer and autumn, the masses of green matter
would float to the surface, rapidly disengaging oxygen as the
sun shone upon them, and sinking again to the bottom with
the coolness of theevening. Later in the year, masses would
adhere to the inner surface of the bottle in the form of a thin
pellicle, or collect in slimy masses, which appeared to dis-
solve with the warmth of the coming spring. The green
colour changed to that of a reddish-yellow, and it might have
been thought that all was dead, did not the microscope show
the same beautiful green both in young and full-grown plants,
together with much bright red and brown, apparently the
casings of the sporangia, which gave their colour to the
wheel-animalcules that had evidently feasted on their remains,
and thriven on them. Large Cosmaria, still in active motion
(the remains of the mature growth of the preceding summer),
lay imbedded in the mass, when a small portion was sepa-
rated for microscopic observation, as well as clusters of young
ones, figured at figs. 31, 32, 33. When the bottles had re-
mained more than a year untouched, except for change of
water, these masses increased in leathery hardness: green life
was not extinct, but became feeble in colour, and too much
changed to warrant further observations ; while a small por-
tion, placed in another bottle and more freely exposed to the
light, multiplied with great rapidity. Further observations
were stopped by the declining strength of the plants.

From the observations of the Rev. Mr. Osborne, on Closte-
rium lunula, published in the ‘Quarterly Journal of Micro-
scopical Science,’ I should feel no doubt that the advancing
motion in Cosmarium was also caused by cilia, the two families
bearing a close resemblance to each other in their habits.
Many careful observations made on Closterium, as detailed in
the ‘ Annales des Sciences Naturelles,’ vol. v., 1836, have been
verified here in Cosmarium, though I am inclined to differ on
the subject of the development of the sporangium. This body
would appear to me to be the winter-casing of a large number of
young plants, which escape from it by rapidly knocking against
its walls when these have been loosened by spring warmth,
or which grow up as the walls gradually decay in the midst of
those gelatinous masses previously described. In proof of
this opinion, | would adduce the immense increase in the
number of the plants in the springs of 1852 and 1853, in
some measure to be attributed to subdivision, as could be
seen by the empty double cases figs. 14 and 21, but yet
trifling as compared with the masses, of which figs. 31, 32,
and 33, give only a faint idea. Why should such rapid

Address of the President at the Annual Meeting. at

motion be observed in the full-grown plant, unless for the
purpose of reproduction ? for the cells of higher plants show
such powerful mechanism merely for the vegetative processes.
If these moving granules are zoospores, capable, when set
free, of developing into perfect plants, then it seems to follow
that the sporangium (which is the product of two such plants)
may also contain these zoospores, capable, when their fitting
time comes, of filling the waters with their countless progeny.
And if, as I fully believe, fig. 29 is the sporangium of a
Cosmarium, its growth by zoospores seems evident.

Appress of the PRrestipent at the ANNUAL MEETING of the
Microscopicat Society, February 28, 1855.

GENTLEMEN,

Tue Report of your Council cannot, I think, be other-
wise than satisfactory, as regards both the progress of our
Society in number of Members, and the state of our finances.
Including the elections which we have made this evening, we
have added twenty-five new names to our list, whilst we have
lost five by death and five by resignation ; making an addition
of fifteen to our total. ‘The number of nominal Members,
however, has been considerably reduced by the stringent mea-
sures which your Council had thought it right to adopt, in
regard to those individuals from whom long arrears of sub-
scriptions are due. Of these, four have been taken off the list,
as never having performed the first condition of membership,
namely, payment of the entrance-fee and first subscription ;
whilst eight more who had become entitled to membership,
have been expelled, after ample notice had been given to them
of the penalty which they incurred. I am quite sure that you
will not regret the loss of those who have shown themselves so
unworthy of the advantages which membership confers ; and
that the vitality of our trunk will be increased by thus getting
rid of all our dead branches.

The financial condition of the Society affords matter for
much congratulation ; since we have been able to afford con-
‘siderable additions to our expenditure, without more than such
a trifling reduction of our floating balance, as we may expect
to be soon made up by that increase of contributions which is
continually going on, whilst our reserve fund has considerably
increased. Thus, we have paid to the editors of the ‘ Quarterly
Microscopical Journal of Science’ a much larger sum than has
ever been before expended in any one year for the printing of
our Transactions; whereby each of our Members becomes

38 Address of the President at the Annual Meeting.

entitled to receive the Journal free of cost, thus getting back
more than three-fourths of the amount of his’ subscription.
We have borne the increased rent charged to us by the
Horticultural Society ; and we have, in addition, felt justi-
fied in laying upon the Society’s funds the cost of the tea
furnished at the evening meetings, which had been previously
defrayed by private subscription.

Among the Members whom we have had the misfortune to
lose by death durmg the past year—namely, the Rey. J. P.
Bean, Professor E. Forbes, Mr. Finch, Mr. Ingpen, and Dr.
Soulby—there i is one whose high scientific eminence claims a
special tribute on this occasion; a tribute which, from my
own long personal friendship with him, I feel it a privilege to
have this opportunity of paying to his memory.

The unexpected death of Professor Edward Forbes, on the
18th of November, at the age of thirty-nine years, excited but
one feeling of the deepest regret, not only in the scientific
community of which he was so distinguished a member, but
also throughout a far wider circle of persona] friends than it
falls to the lot of most men to possess. It was my good
fortune to have first become acquainted with him at the time
when we were fellow-students, nineteen years since, in the
University of Edinburgh; where be went through the full
curriculum of medical study, but did not take his degree;
having, during his sojourn there, determined to abandon the
pursuit of Medicine as a profession, in order to devote himself
to the study and teaching of Natural History, for which he
had very early shown a strong bias and a remarkable aptitude.
The enlarged and philosophic spirit in which he pursued this
science, is too widely known and too generally appreciated, for
it to be necessary for me to dwell upon it here. His admir-
able monograph on the “ British Starfishes,’ published in
1840-1, was the first work by which he became generally
known as a Naturalist; and very shortly after its appearance,
he commenced those laborious researches in the Avgean Sea,
on the distribution of marine life at different depths, which
first brought him prominently into notice among the eminent
cultivators of geological science of this and other countries,
by whom his investigations were most highly estimated. From
that time his scientific career was one of increasing honour to
himself, and of the most eminent service to the sciences of
zoology and geology, which he was continually enriching by
original contributions of the greatest value.

He was successively appointed to the Professorship of
Botany in King’s College, to the office of Paleontologist to the
Geological Survey, and to the distinguished post of President

Address of the President at the Annual Meeting. 39

of the Geological Society ; all of which he resigned last spring,
on being chosen to succeed the late Professor Jameson in the
Chair of Natural History in the University of Edinburgh,
which he had long regarded as the summit of his ambition,
but upon the duties of which he had scarcely entered, ere his
life was cut short by the development of a disease, which (as
the event proved) must long have been pursuing its fatal course
without any external indication. |

To know the Professor was to know but little of Edward
Forbes. Probably no man of his generation was so many-
sided. Not only science, but literature and art, found in him
a hearty appreciation of all that was excellent. No clique
could claim him as its own, for his sympathies were universal ;
no man was more unselfish, or used his influence more gene-
rously for the advancement even of those who might be in some
sort his rivals, than Edward Forbes. Hence no one could
know him, without not only admiring, but loving him; and to
every one who was worthy of his regard, he freely extended it.
His genial humour and good-natured wit, joined to his other
high qualifications, caused him to be universally welcomed as
a companion; yet, however “petted,” he was never “ spoiled”
by the attentions he received, but remained the same genuinely-
good fellow, when he had climbed to the top of the tree, as he
was when, in the days of his studentship, he exercised that
wonderful power of attaching others to him, which would have
doubtless been exerted to the great advantage of his University
and of science, had it been the will of Providence that his
labours should have been prolonged in the new sphere on
which he had so recently entered.

Turning, now, to our own proceedings during the last
twelvyemonth, I cannot but feel some regret at not being able
to speak in a more congratulatory tone, as to the number and
importance of the communications which have been brought
before us. Considering the great number of individuals who
are occupied in microscopic research, and the large amount
of novel facts which they must be continually encountering, it
is to. me a matter of surprise, as well as of regret, that so few
of these should be made public through our instrumentality.
Some of the best contributors to our former meetings have, I
am aware, been kept back during the last year by the pressure
of other engagements; whilst others have entered with such
zeal into the study and practice of the Photographic art, as to
have been led away by its fascinations from their former alle-
giance. Moreover, during the latter part of the last session,
I understand that a dearth of papers was an epidemic disease
by which almost every scientific society in London was more

40 Address of the President at the Annual Meeting.

or less affected ; so that we were thus suffering (if this be re-
garded as any alleviation of our trouble) in the good company
of the Royal, the Linnean, and other first-rate associations.
I would urge upon our Members, however, that the interest of
our meetings can only be sustained by themselees ; we have no
right to look for extraneous assistance ; and there is, | am con-
fident, no lack of power amongst us, if it be only rightly directed,
—a point on which I shall by-and-by dwell more at large.
But I would also suggest to those distant friends to micro-
scopic inquiry, who are in the habit of forwarding their valuable
communications direct to the Journal, that it would much serve
us, and would give to their discoveries a more immediate and
a wider publicity, if they would communicate them in the
first instance to the Microscopical Society (which they can
always do through some Member, or through the editors of
the Journal), so as to be read and discussed at our meetings.

The only communication we have received, having reference
to the improvements of the microscope, or of any of its adjuncts,
is Mr. Wenham’s valuable paper on Microscopic Photography ;
which will, I doubt not, give a new impulse to the practice of
this most interesting art. Having myself been one of the
earliest labourers in this field, although circumstances have
prevented me from continuing to cultivate it, I can fully con-
firm what he says with regard to the superiority of solar light
over any ordinary kind of artificial light. With low powers,
indeed, and a sufficiently large condenser, I have found diffused
daylight much superior to the direct rays of the sun: of course,
a longer time is required for the production of a good picture ;
but no adjustment is necessary for the change of the sun’s
place; and the picture itself is much superior in tone to most
of those taken by direct sunlight, It is much to be desired
that the experiment should be tried, how far the electric light
possesses such an amount of actinic power, as may make it an
efficient substitute for the solar rays; the result of Mr.
Wenham’s experiments upon the effect of an intermitting dis-
charge of a small Leyden jar, being sufficiently encouraging
to render the trial of it highly desirable.

Before passing to the review of that portion of our proceed-
ings which will lead us to considerations of a very different
order, [ think it not inappropriate to make a few remarks upon
certain tendencies which I observe at present among some of
those who are most zealously devuted to microscopic research,
and which seem to me to be likely to exert an injurious influ-
ence upon the progress of science, if they be not kept within
due bounds. I refer especially to that rage, if | may so desig-
nate it, for object-glasses of the largest possible aperture,

foe ae ee ee

Address of the President at the Annual Meeting. Al

which causes our best makers to aim at its augmentation, as if
it were the one thing needful. Now if we examine into the
comparative advantages and disadvantages of such glasses, we
shall find, I think, that for all ordinary purposes, the. latter
decidedly predominate. The objects which can be seen de-
cidedly better with lenses of very large, than with those of
moderate aperture, are comparatively few in number, and of a
very limited kind ; being such as are marked with very close
lines, striz, spots, or other like inequalities of surface. For
the resolution of these, it is well known that a large angular
aperture is essential ; so that of two lenses whose performance
may be equally good for all ordinary purposes, that which has
the wider angle shall here surpass the other, and this in exact
proportion to its excess. But this superiority is obtained at
the expense of other advantages. For even granting that there
is no sacrifice of that most important element, defining power
(which can only be obtained, with a very wide angle, by the
utmost perfection in all the corrections), yet the adequate
performance of such a lens can only be secured by the greatest
exactness in the adjustments. Only that portion of the object
which is precisely in focus, can be seen with an approach to
distinctness, everything that is in the least degree out of it
being imbedded (so to speak) in a thick fog; it is requisite,
too, that the adjustment for the thickness of the glass that
covers the object, exactly neutralize the effect of its refraction ;
and the arrangement of the mirror and condenser must be such
to give to the object the best possible illumination. If there
be any failure in these conditions, the performance of a lens
of very wide angular aperture is very much inferior to that of
a lens of moderate aperture ; and except in very experienced
hands, this is likely to be generally the case. Now to the
working microscopist, unless he be studying the particular
class of objects which expressly require this condition, it is a
source of great inconvenience and loss of time, to be obliged to
be continually making these adjustments ; and a lens, which,
when adjusted for a thickness of glass of 1-100”, will perform
without much sensible deterioration with a thickness either of
1-80” or of 1-120", is practically the best for all ordinary
purposes. Moreover, a lens of moderate aperture has this
very great advantage, that the parts of the object which are
less perfectly in focus can be much better seen; and therefore
that the relation of that which is most distinctly discerned to
all the rest of the object, is rendered far more apparent. Had
not the term ‘ penetration’ been already applied in a different,
and I think far less appropriate sense, | should have said that
an objective of moderate angular aperture has far more pene-

42 Address of the President at the Annual Meeting.

trating power, enabling us to see much more into an object,
than one of a very wide angle; and generally speaking, its
definition will also be found superior. :

Let me remind you, further, that almost all the great
achievements of microscopic research have been made by the
instrumentality of such objectives as I am recommending.
There can be no question about the large proportion of the
results which continental microscopists may claim, in nearly
all departments of minute anatomical, physiological, botanical,
or zoological research, since the introduction of this invaluable
auxiliary ; and it is well known that the great majority of their
instruments are of extremely simple construction, and that
their objectives are generally of very moderate angular aper-
ture. Moreover, if we look at the date of some of the prin-
cipal contributions which this country has furnished to the
common stock, such as the “Odontography” of Professor
Owen, the “ Researches into the Structure of Shell” carried out
by Mr. Bowerbank and myself, the ‘‘ Physiological Anatomy”
of Messrs. Todd and Bowman, the first volume of the ‘* His-
tological Catalogue,” by Professor Quekett, and the “ British
Desmidez” of Mr. Ralfs, we find sure reason to conclude that
these researches must have been made with the instrumentality
of lenses, which would in the present day be regarded as of
very limited capacity.

I hope that in these remarks I shall not be understood as in
any way desirous to damp the zeal of those, who are applying
themselves to the perfectionizing of achromatic objectives. I
regard it as a fortunate thing for the progress of science, that
there are individuals whose tastes lead them to the adoption
of this pursuit ; who stimulate our instrument-makers to go on
from one range to another, until they have conquered the dif-
ficulties which previously baffled them, and then apply them-
selves to find out some new tests which shall offer a fresh
difficulty to be overcome. But it is not the only, nor can I
regard it as the chief work of the microscope, to resolve the
markings upon the Diatomacee, or tests of the like difficulty ;
and although I should consider this as the highest object of
ambition to our makers, if the performance of such lenses
with test-objects were any fair measure of their general utility,
yet as I think that I have demonstrated that the very conditions
of their construction render them inferior in this respect for
the purposes of ordinary microscopic research, I would much
rather hold out the reward of high appreciation (we have no
other to give) to him who should produce the best working
microscope, adapted to all ordinary requirements, at the lowest
cost. It does not seem to me an unapt simile, to compare the

Address of the President at the Annual Meeting. 43

devotees of large angular apertures to the gentlemen of the
‘turf.’ It is, I believe, generally admitted, that the breeding
a class of horses distinguished by speed and ‘blood,’ which is
kept up by the devotion of a certain class of our countrymen
to the noble sport of racing, is an advantage to almost every
breed of horses throughout the country; tending, as it does,
to develop and maintain a high standard in these particulars.
But no one would ever think of using a race-horse for a roadster
or a carriage-horse, knowing well that the very qualities which
most distinguish him as a racer, are incompatible with his
suitableness for ordinary work. And so I think that the
‘breeders’ of first-class microscopes (if I may so designate
them) are doing great service, by showing to what a pitch of
perfection certain kinds of excellence may be carried, and by
thus improving the standard of ordinary instruments ; notwith-
standing that for nearly all working purposes, the latter may
be practically superior.

Turning now to those contributions which exhibit the uses
of the microscope in scientific research, I find that the
first paper which came before us, that of Mr. Jabez Hogg on
the development and growth of the Lymneus. This memoir,
although treating of a subject which has already been studied
more minutely than the author seems to have been aware of,
has nevertheless added some facts which I believe to be new,
and which are of great physiological interest; I refer to those
which relate to the retardation of the developmental process, by
insufficiently supplyig the animal with food. ‘The nourish-
ment of the embryo is obtained by means of the current
produced by the cilia clothing its tentacles (which is also sub-
servient to the function of respiration), until the gastric teeth
are sufficiently matured to enable the animal to cut by their
means the vegetable substances growing in the water, when the
ciliary fringe disappears. But if, Mr. Hogg informs us, the
young animal be kept in fresh water alone, without vegetable
matters of any kind, it still retains its cilia, and attains only
to a small size; and its gastric teeth are but very imperfectly
developed ; and if it be confined to a small narrow cell, it will
only grow to such a size as will enable it to move about freely.
By these means Mr. H. has been able so to retard the develop-
ment and growth of the embryos, that at the age of six months,
though apparently healthy and active, they were only as far
advanced as ordinary embryos two or three weeks old; whilst
other animals of the same brood and age, placed in circum-
stances favourable to their growth, had attained their full size,
and had produced young, which were of the full size of their
elder relations. The physiologist is reminded, by these curious

44 ‘Address of the President at the Annual Meeting. ‘

facts, of the well-known experiments of Dr. W. F. Edwards
‘upon the development of the Tadpole, and of the more recent
experiments of ‘Mr. Higginbottom upon the same subject;
and as there is some difficulty in reconciling these two sets of
results, I would strongly recommend Mr. Hogg and other
mienabers of our society to follow up the inquiry, by a more
extended series of investigations into the circumstances which,
separately or combined, affect the development of the Lymneus
especially the influence of light and temperature, supply of
food and oxygen, and limitation of space; the last, I suspect,
taking effect through the limitation of food and oxygen.*
Professor Gregory has continued his interesting communi-
cations upon Diatomacee ; and one of the papers with which he
has favoured us has a very important bearing upon a question
‘which is exciting great interest among really scientific natural-
ists at the present time, viz., the range of variation within the
limits of species. For in almost every department, both of
Zoology and Botany, it is coming to be generally felt, by
those who have devoted themselves to the inquiry in a truly
philosophical spirit, that there has been by far too great a
readiness to establish new species, and to confer new names,
for the sake of distinguishing: forms, which, when more care-
fully compared, are found to pass into one another by imper-
ceptible gradations, or to be but different states of the very
same organism. ‘The time is now, | hope, entirely past, when
the extent of a naturalist’s acquirements in any particular de-
partment, were estimated by the number of species in his
collection, instead of by the amount of his knowledge of all
that concerns them. Yet still we find that what I may desig-
nate as the mere collector’s spirit is far too widely prevalent ;

* TI feel it requisite to take this opportunity of correcting an error into
which Mr. Hogg has fallen, in alluding to my observations on the struc-
ture of Shells, and comparing them with those of Mr. Bowerbank. He
represents me (Transactions, vol. ii., p. 96) as inclining to the opinion of
Reaumur, who considers Shell an inor ganic exudation from the surface
of. the dermis ; whereas the whole aim of my descriptions was to prove
that Shell is an organized cellnlar tissue, being, in fact, a calcified epi-
dermis. It is true that I disagree with Mr. Bowerbank (whose opinions
Mr. Hogg supports), in maintaining that Shell is not vascular in the ordi-
nary sense of the term ; that is, is not penetrated by blood-vessels from
the subjacent tissue. But it no more hence follows that it is not endowed
with vitality, than that epidermic and epithelial structures, or cartilage,
are dead or inorganic, because they have no vessels ; and the increase and
reparation of shell may well take place, like those of the tissues just
named, at the expense of nutriment brought to it by the vessels of the
subjacent surface, although that nutriment is not distributed through it
by the extension of those vessels into its substance. Mr. Hogg appears
to have laboured under the very common error, of supposing that what is
non-vascular must necessarily be inorganic also.

Address of the President at the Annual Meeting. 45

and that the first impulse of many observers, when they meet
with a type which is new to them, is to give it a name and a
place in systematic arrangements. Hence Botany and Zoology
become loaded with a multitude of names, designative of what
even a small amount of care and patience will suffice to show
are identical species; and almost every widely-diffused plant
or animal bears a mass of synonyms, which are extremely
perplexing to the inexperienced naturalist, and very trouble-
some even to him who knows how to estimate them aright.
Thus, as Dr. J. D. Hooker remarks, the Pteris aquilina, one of
the most widely-diffused of all Ferns, has received a different
name in almost every country in the world; and among the
plants of New Holland, which were at one time supposed to
be altogether dissimilar to those of Europe, and which were
described and named as new species, no fewer than 150 have
been ascertained by Mr. Robert Brown to be identical with
European plants. All such synonomy, which has been rightly
characterized as “the opprobrium of science,” owes its exist-
ence, as has been recently well remarked by the Rev. W.
Smith (‘ Microscopical Journal,’ vol. iii., p. 130) “ to imperfect
knowledge, imperfect observation, or imperfect judgment.”

It is not, however, to the synonymy resulting from careless
ignorance of the identity of the supposed new forms with such
as have been previously described, that I wish to direct your
attention at the present time; but to that resulting from a too
great readiness to consider every departure from a certain type
to which a particular designation has been attached, as enti-
tled to rank as a specific distinction. I believe that this dis-
position has often been unduly indulged, under the idea that
the making of new species was an acceptable contribution to
Natural History, and gave to the maker the prestige of an
original discoverer ; in other instances it has been favoured
by the preconceived notion, that the plants or animals of
newly-discovered, isolated, or little-visited localities must
necessarily be new; but even putting aside all influences of
any such kind, [ think it unquestionable that a vast multipli-
cation of species has taken place, from a misapprehension of
the value of distinctive characters, depending upon an entire
ignorance of, or a very imperfect acquaintance with, the
capacity of particular species for variation. It needs to be
constantly borne in mind, that no general rules can be laid
down with respect to the value of characters, that shall be of
universal applicability. It frequently happens that in two
groups, closely allied to one another, characters of the very
same kind shall be sufficiently constant in one of them to be
quite reliable as specific distinctions, whilst in the other they

46 Address of the President at the Annual Meeting.

are altogether valueless for such a purpose. Thus the family
of Felines, taken as a whole, is one in which great importance
may be attached to the markings of the surface; so that,
although the skeletons and teeth of the various species differ
but little from each other except in size, yet the constancy of
these surface-markings in large sets of individuals, suffices: to
mark each set as specifically isolated from every other. We
find, moreover, that the Felines generally are but little capable
of adapting themselves to a variety of external conditions, so
that each species is limited to a certain geographical area,
beyond which it has no tendency to disperse itself, and within
which it has no disposition to vary. But when we turn to
the domestic Cat, we find a completely opposite state of things ;
for we at once perceive that this species is endowed with a
most extraordinary capacity for variation ; in virtue of which
we not only find its constitution adapting itself to a great
diversity of climates, of food, of habits, &c.; but all those
nameless influences which may be included under the general
term ‘ domestication,’ tend to produce a special tendency to
want of uniformity in that very particular—the surface-mark-
ing—which is so constant in the undomesticable species.
Thus, then, we see that the capacity for variation, which
seems inherent in the constitution of certain beings to the
exclusion of others, not only enables the former to extend
themselves where the latter cannot follow them, but brings
them under a new set of influences, which themselves tend to
increase the range of their variation. Asa general rule, there-
fore, we may expect that a widely-diffused species should ex-
hibit a considerable extent of this range; which may show
itself not merely in obvious adaptations to diversities of
climate and of external circumstances, but also in departures
from what. we are accustomed to regard the typical character,
of a kind that does not seem reducible to any known opera-
tion of causes.

Having for many years made this topic a special subject
of inquiry, from its connexion with the much-discussed ques-
tion of the specific unity or diversity of the human races, | am
able to confirm the curious general principle long since laid
down (though probably in too formal and stringent a manner)
by Mr. Swainson, that in every natural group, whether large
or small, there seem to be some divisions which are endowed
with a remarkable degree of this capacity for variation, whilst
there are others which are as remarkably deficient in it ;-and
hence, that characters which are quite sufficient for the sepa-
ration of species in the latter case, must be regarded as merely
indicative of individual variation in the former. _

Address of the President at the Annual Meeting. 47

If, then, it be asked how we are to distinguish the groups
of fixed from those of variable character, | answer,—in no
other mode than by the comparison of large numbers of indi-
viduals; and by bringing together the subjects of our com-
parison from the widest range of external conditions under
which they are found to exist. It is only by a very extensive
comparison of forms, even when brought from the same
locality, that we are justified in pronouncing a probable
opinion as to their specific isolation; so often does it happen
that when we have chanced first to meet with two specimens
which we should be disposed to rank as distinct species, on
account of their obvious differences, the supposed boundary
between them is altogether done away with by the subsequent
discovery of osculant forms, which establish a complete transi-
tion from one to the other, so that no line of demarcation can
possibly be drawn between them. And when we come to com-
pare together suites of specimens from different localities, the
danger of error from reliance on a small number of individuals
is still mere multiplied ; since their divergent forms are likely
to be more numerous and more strongly marked, and some of
the intermediate links may be wanting. Even where such defi-
ciencies exist, if we find two sets of forms manifestly tending
one towards another, and each of them exhibiting a considera-
ble range of variation, we shall generally, I feel sure, err on
the right side in uniting them under a single specific designa-
tion, rather than in ranking them as distinct species.

The enormous multiplication of species which loads our
systematic treatises and monographs, is in great measure due,
I feel assured, to the neglect of this rule of comparing exten-
‘sive series of individuals, and of taking particular note of the
transitional forms. I could give you an example in which this
has been done (within my own knowledge) to such an extent
as, in the naming of shells from a new locality, to make three
or four times as many species as can really be said to exist;
thus encumbering science with a vast number of useless de-
scriptions, and placing those who may chance to come into
possession of the intermediate forms, in the utmost perplexity
as to the naming of their specimens in accordance (which they
feel bound to do) with those descriptions. But I will adduce
an illustration, drawn from a department of microscopic in-
quiry, to which it is known to most of you that I have paid
special attention, viz., the group of Foraminifera. Very
early in my study of this group, which was commenced
upon collections that were rather rich in individuals than in
species, I came to the conclusion that it is (as a whole) pre-
eminently distinguished by its capacity for variation ; and

48 Address of the President at the Annual Meeting.

that a large proportion of the species, and even of the genera,
which have been distinguished by systematists, and especially
by M. D’Orbigny, have no real existence, being nothing
else than individual varieties. As I purpose to commu-
nicate the results of my researches to the Royal Society, by
whose liberal assistance I have been enabled to procure the
execution of the beautiful series of microscopic drawings
which I have exhibited to you from time to time, I am pre-
cluded from entering into anticipatory details; but I may
mention that having had the opportunity some time since, of
submitting my suites of specimens to a distinguished French
Zoologist, and having directed his attention to a set of figures
in M. D’Orbigny’s “ Fossil. Foraminifera of Vienna,” which,
though there described under different names, were clearly
proved by the continuity of my connecting series to be but one
and the same, I asked him how it was possible for a naturalist
of M. D’Orbigny’s experience to make such blunders, -His
reply was, that the matter, was perfectly simple, when M.
D’O.’s mode of working was known ; for that, in examining any
new collection, he set an assistant to pick out the most diver-
gent forms, and then described all that might prove new to
him as distinct species, without troubling himself in the least
about those connecting links, the existence of which should
have at once convinced him that he was following an altogether
wrong method. ‘Throughout the whole of his labours on this
group, in fact, I trace the influence of the erroneous ideas
which he originally entertained in regard to the nature of the
animal of the Foraminifera; for in the formation of his
orders, as well as of his genera and species, he has proceeded
as if the characters of the testaceous skeleton were of the same
distinctive value,—when its construction is due merely to the
solidification of the surface of a minute fragment of animal
jelly, which is subject to an almost indefinite variation hoth
in size and in shape,—as when it belongs to a mollusk of high
organization, the plan of whose conformation is definitely
fixed. I am happy to be able to add, that having recently had
an opportunity of comparing the results of my observations,
chiefly made upon the Australian and Philippine Foraminifera,
with those of Professor Williamson (of Manchester), which
have been chiefly made upon British forms, I have had the
satisfaction of finding his conclusions to accord so closely with
mine, that I cannot entertain the slightest doubt of their
general truth. We both of us find that there are certain
species whose range of distribution is limited, and whose form
is remarkably constant; but we also find that in by far the
greater number of cases, the species of Foraminifera are dis-

Address of the President at the Annual Meeting. 49

tributed over very wide geographical areas, and have also an
extensive geological range; and that when a collection is
brought together containing large numbers of individuals of
one generic type, which appear, however, to belong to several
distinct species, it very commonly happens that although it
would be easy to make 6, 8, 12, or 20 species, by selecting the
most divergent forms, yet that, when the attempt is made to
sort the entire collection under these types, only a part of it
can be unhesitatingly arranged around them as centres, the
remainder being transitional or intermediate forms, for which
another set of species must be made, if the principle of sepa-
ration be once adopted. In fact, to such an extent does indi-
vidual variation often go, that (as in the case of the buman
race) no two specimens are precisely alike; and there is no
satisfactory medium between grouping them all as varieties of
one species,and making every individual a species, which is
manifestly absurd. i Peli

Now it evidently requires a much greater amount of care-
ful and laborious research, thus to ascertain the specific unity
of forms which would undoubtedly be pronounced diverse by
a superficial observer, than to erect these into new species ;
aud I cannot but think that he deserves better of science, who,
by the painstaking collection and comparison of great num-
bers cf individuals, affects a reduction in the aggregate of
species, than he who, because he meets with a form that he
cannot find to have been previously described, forthwith
makes an addition to the vast mass already enumerated ;
without stopping to determine, by adequate research, whether
its features of distinction are permanently and constantly
presented, or whether they are liable to shade-off into the
characters of the forms previously known.*

I have dwelt at what may seem disproportionate length
upon this topic, because I think it is one as to which every
naturalist of the physiological school is bound to enter his
protest, upon every suitable occasion, against that spirit of

* Since the delivery of this address, I have had the pleasure of finding
that the same thought had been previously expressed, almost in the same
language, by my friend Dr. Jos. D. Hooker; who, in a note to his ‘ In-
troductory Essay on the Flora of New Zealand’ (which notices many
flagrant examples of the mistakes of species-makers regarding New Zea-
land plants), thus remarks :—‘‘ The botanist who has the true interests
of science at heart, not only feels that the thrusting of an uncalled-for
synonyme into the nomenclature of science is an exposure of his own
ignorance, and deserves censure, but that a wider range of knowledge and
a greater depth of study are required to prove those dissimilar forms to be
identical, which any superficial observer can separate by words and a
hame.”. '

e

50 Address of the President abiehe Annual Meeting.

species-making, which is one of the greatest obstacles to all
truly scientific progress, alike in systematic Zoology and
Botany, in the Geography of plants and animals, and in
Paleontology. I am happy to say that in regard to the
particular subject which suggested these remarks, namely,
the range of variation among the Diatomacee, I find the
highest British authority upon that tribe, my friend Professor
W. Smith, to be quite in accordance with me; and strongly
recommend an attentive perusal of his paper ‘On the deter-
mination of Species in the Diatomacee’ (‘ Microscopical
Journal,’ January 1855) to all who are engaged in the study
of that group. I would particularly direct their attention to
his remark, that to adopt as specific a shape or size that may
occur in all the individuals, however numerous, of any one
gathering, is liable to lead to fallacious results, from the
circumstance that all these specimens may have been pro-
duced by self-division from a single individual ; and that as,
in each such division, the characters of the original are
perpetuated, a modification of the outline of each individual
in the entire collection, may arise from some accidental cir-
cumstance which affected that of the primordial frustule.
Hence neither size nor outline are sufficient to mark the spe-
cies among Diatomacee : it is requisite to compare specimens
from different localities, in order to determine with tolerable
certainty, what is the average or typical form and magnitude
of any species ; and its range of variation must be determined
by a comparison of forms brought from every known habitat,
before the extent of departure which should be held to consti-
tute a distinct species, can be even approximately determined.
Thus Professor Gregory shows. us (loc. cit.) that under the
general category of Navicula varians may be ranked a consi-
derable number of forms, differing widely in shape, but seem-
ingly tolerably constant in number of stria (the range of
variation of these being apparently from 14 to 18 m :001’,
and the usual number being 16), which have been described
under different specific names; whilst there is another very
analogous group of reputed species, but also seeming to be
tolerably constant to a very different number of striz (their
range of variation being apparently from 24 to 26 in :001"),
which he proposes to designate as NV. mutabilis. Now it must
be considered an open question, to be only decided by the
examination of collections from a much greater number of
localities, whether these two comprehensive species are not
themselves in reality but one; since it is quite certain that
there are species in which the range of variation in the
number of strie is much greater than from 18, the greatest

Address of the President at the Annual Meeting, el

number in W. varians, to 24, the least number in N. mutabilis ;
and looking to the great capacity for variation shown by both
forms, the probability seems to me to be decidedly in favour
of their specific unity.

Passing on now to the other papers which have been read
‘since the last Anniversary, [ come to my own ‘On the Deve-
lopment of the Embryo of Purpura lapillus,’ on which, of course.
it is not for me to comment. I may, however, be permitted
to make one or two remarks, in relation to the general subject,
and the methodof the investigation :—First, that it affords
an example of what may be done with very simple means,
since the greater part of the inquiry was worked-out under
-single lenses, Mr. Quekett’s dissecting-microscope having
-been the instrument chiefly employed, and. the achromatic
‘compound-microscope having only been occasionally resorted
to for more minute examination and for verification. Secondly,
that even a brief space of time may serve to do much, if it be
well employed; my whole sojourn at Tenby was less than a
fortnight, and the greater part of several days was occupied in
the search for living Foraminifera, which were the objects I
had specially in view. Thirdly, that it is of great importance
-to obtain as many facts as possible, as a basis for reasoning ;
and to trust no more to. hypothesis for the connection and expla-
nation of those facts, than is absolutely necessary. The error
of my predecessors lay in imperfect observation (the most
important period in the developmental history hasing . been
passed-over by them), and in inventing a theory to fill up the
hiatus, which proved not only to.be fundamentally erroneous,
but to have given a wrong colour (so to speak) to all their
statements of fact. Now it happened to myself, that although
I had seen quite enough to satisfy me that their notion of the
process was altogether erroneous, and had formed a decided
opinion as to what was its real nature, I failed in obtaining
that. positive assurance of its truth which alone would have
justified me in putting it forward as an ascertained fact, until
the very last day of my researches; when I had the good for-
tune to alight upon a group of Purpura-capsules, at such a stage
of development that almost every one of them contained young
embryoes of : different sizes, attached to the conglomerate
vitellus, and obviously. ingesting its particles; and these I
was able not only to observe for myself, but to exhibit to my
friends, who had previously seemed doubtful how far my expla-
nation of the mode in which the large embryoes were formed,
was more to be trusted than that. of my predecessors, MM.
Koren and Daniellsen. [I would add that any one who has
the opportunity of paying even a short visit to any shore, on

e 2

52 Address of the President at the Annual Meeting.

which the egg-capsules of other pectinibranchiate mollusks
are to be met with in any quantity, will do a most acceptable
service to science, by determining how far the same history is
common to other species; and I would particularly instance
the Buccinum undatum, or common Whelk, whose egg-cap-
sules are to be found in masses upon almost every shore
during the spring months, and the history of whose develop-
ment, though studied by MM. Koren and Daniellsen, has
probably been as much misunderstood and misdescribed by
them, as I have shown that of Purpura to have been. '

With respect to the paper read at our last Meeting, on
Desnidium margaritiferum, I am in like manner precluded
from making the comments which I might have otherwise
offered, by the circumstance that its authoress is a near
relative of my own, and that it was communicated to the
Society through myself. I may remark, however, that I
preferred that it should come before the Society in its ori-
ginal simple form, rather than myself work it up into a more
formal and systematic memoir ; because I considered it to be a
good example of a style of contribution to Science which is
much needed, and which it is within the power of even the
unlearned microscopist to furnish, provided only he be com-
petent as an observer, and truthful as a narrator of facts,—I
mean a simple record of observations upon single types of
structure, carried on over a long period of time, so as to aid in
the determination of the changes which they present in the
course of their development. ‘This is particularly needed with
regard to the whole group of Infusorial Animalcules, our
knowledge of which may be said to be only in its infancy ;
for notwithstanding the industry with which these objects
have been studied by Professor Ehrenberg, and the prestige
he has acquired with the public as the highest authority in
regard to them, yet it is progressively becoming more and
more evident, that the whole of the great fabric which he has
erected rests upon a most insecure foundation, and that the
Anatomy, Physiology, and Systematic arrangement of the Infu-
soria, need to be restudied completely ab initio. For, in the first
place, there can be no doubt whatever, that a large proportion
of the so-called infusory animalcules belong to the vegetable
kingdom, and that a great number of the species described
by Professor Ehrenberg and other observers of the same class,
are but different phases of development of one and the same.*
Further observation will doubtless lead to much additional
light upon this subject, many parts of which are still wrapped

* See, for example, Cohn’s ‘Memoir on the Natural History of Proto-
coccus pluvialis,’ published by the Ray Society, 1853.

Address of the President at the Annual Meeting. 53

in deep obscurity ; for it can scarcely be doubted that many of
the animalcule-like bodies, such as the Volvocine, whose
vegetable nature has been made known to us by observation
of certain stages in the history of their lives, are but the
motile forms (zoospores) of some other plants, whose relation to
them is at present unknown. Hitherto it has been commonly
thought sufficient to trace the history of any of these bodies
from their first production by binary subdivision, or some
essentially-equivalent process (gemmation), to the repetition
of the same process by themselves, which was considered as
terminating their life as individuals; and neither was any
departure from this simple plan of reproduction, nor the
origination of a new and dissimilar form in any part of the
series, at all anticipated. But now that we have juster views
of the real analogies (or, more properly, homologies) of these
simple plants, it becomes evident that the multiplication of
cells by binary subdivision, or by any kind of outgrowth,
really corresponds with the multiplication of elementary parts
in the embryo of any one of the higher plants or animals ;
and that the almost indefinite increase which may thus take
place, is really the growth of the individual, which will at last
take on a new phase, sexual organs being evolved, and a true
process of generation (essentially consisting in the reunion of
the contents of two cells, by conjugation, or some equivalent
act) being performed by their instrumentality. The life of
the individual, as I long since maintained, and as is now coming
to be generally admitted, includes the whole series of pheno-
mena which intervene between one act of generation and
another ; and this series of phenomena may include the pro-
duction of two or three very distinct and apparently unrelated
forms. Hence until we have traced out this history in regard
to every distinct type of animal and vegetable life, we must
not only consider our knowledge of it to be essentially incom-
plete, but we must also admit the probability that a vast
number of our reputed species have no real existence. Many
distinguished German and French observers* have recently
been devoting themselves to this kind of inquiry, singling out
a few specific forms, and endeavouring to trace these through
all their phases of development; and the success which has
already attended their endeavours, is the best encouragement
to more extended labours in the same direction.

* See especially the Memoirs of Professor Stein, in ‘ Weigmann’s
Archiv.,’ and in ‘ Siebold and Kolliker’s Zeitschrift,’ and his recently-
published work, ‘Die Infusionsthiere,’ which embodies the preceding ;
also M. Jules Haime, on Trichoda lynceus, in ‘ Ann. des Sci. Nat.,’ 3° Sér.,
Zool., tom. xix.

o4 Address of the President at the Annual Meeting.

In this work I am extremely anxious to engage the active
co-operation of the Members of our Society. I cannot but
feel that a great deal of excellent microscope power, if I may
use the expression, is running to waste. Of the excellence
of our instruments, it 1s quite unnecessary for me:to speak. Of
the acute powers of observation of a large proportion of the
possessors of these instruments, I am equally well assured.
Yet if we look at the comparative products of England and
Germany, in the field of sound microscopic observation, we
cannot but feel that there is some ground for the sarcastic
observation of Professor Schleiden, that the English cannot
possess good microscopes, since their contributions to minute
botanical research have been so trifling. I would not be thought
unmindful of the many admirable memoirs and monographs,
which may challenge comparison with those of any other
country ; they are excellent as far as they go; but I am san-
guine enough to believe that these could easily be multiplied
tenfold, if those who spend their time in desultory observa-
tions, and in merely looking at some favourite objects over
and over again, would but concentrate their attention upon
some particular topic, and work out this with patience and
perseverance ; and I am not, I think, too ambitious for the
honour of our country, or too eager for the promotion of true
Science, in urging the Members of this Society, that they should,
both individually and collectively, aim at so worthy an object.
I would assure you from my own somewhat lengthened expe-
rience, that the microscopist who applies himself to work out
some particular class of observations, on which he concentrates
his chief attention, finds it gradually become to him an object
of such attractive interest, that he experiences a zest in the
pursuit, to which the mere dilettante is an entire stranger ; and
I feel confident that it is only by the assumption of some
systematic guidance as to what and how to observe, that the
influence of our Society will be most beneficially exerted in
the promotion of microscopic research, and its own highest
prosperity be most effectually secured.

Machine for Microscopic Writing. — 55

AN erat: of Mr. PETERs’s icine for Microscopic
Writine. By R. J. Farrants, Esq., F.R.CS.

(Read April 25th, 1855.)

Most of the Members of the Microscopical Society are un-
doubtedly acquainted with Nobert’s lines, and have probably
considered with astonishment the wonderfully-minute move-
ments which must have been effected in producing them.

Very beautiful specimens of microscopic writing, also by a
foreigner, Froment, of Paris, have, I believe, also been exhi-
bited in thisroom. I am not aware that any account has been
published of the manner in which the results are attained.

It is satisfactory to be able to state that these interesting
productions of our continental neighbours have been at least
equalled by means of a machine, entirely contrived and prin-
cipally constructed by a gentleman of our own country, Mr.
Peters, the banker, who is also a distinguished member of the
Microscopical Society: he makesno secret of the manner in
which his marvellous specimens are produced: on asking
leave to lay before this Society an account of his wonder-
working machine, and the manner of using it, permission was
at once most liberally given; and that the description may be
the more intelligible, he has kindly allowed the machine itself
tobe placed on the table. Being thus enabled to point to
the machine, the need for accurate drawings of it, is in a great
measure superseded ; still, some figures have been prepared
with a view to render the details of its construction more easy
of comprehension: these, however, are diagrams merely, and
have no pretension to be considered drawings of the instru-
ment.

The machine had. its origin in the following circumstance :
Mr. Peters, having been shown some microscopic writing,
executed, I believe, by Froment, of Paris, expressed his belief
that he could produce writing as small: this opinion was re-
ceived with extreme incredulity ; Mr. Peters, however, feeling
confident of the sufficiency of his plan, determined to test it
by actual trial: the result is a machine capable of executing
and recording movements of almost inconceivable minuteness :
with it, in its present condition, Mr. Peters has written “ The
Lord’s Prayer,’ (in the ordinary writing character without
abbreviation or contraction of any kind) in a space not exceed-
ing the one hundred and fifty thousandth, 1-150,000th of a
square inch. ‘There’are in this specimen six lines of writing ;
the length of the sides of a parallelogram, to include the whole,
would be 1-250th and 1-600th of an inch linear: the area so
included is (1-250 x 1-600 =) 1-150,000th of a square inch :

56 Machine for Microscopie Writing.

the height of the letters is 1-10,000 of a linear inch, so that
the space occupied by the letters a@ or n, or such as are about
as wide as they are high, is no more than 1-100, ii 000th,
the hundred millionth of a square inch.

In examining the construction of the machine, it will be
convenient to consider, first, The Frame or Stand, and then
THE MECHANISM ; referring in succession to (1) the arrange-
ments for transmitting and diminishing motion; (2) those for
controlling and directing the moyements ; (3) nid lastly, the
contrivances for j preserving traces of those movements which it
is wished to record, so that they ey be viewed with the
microscope.

‘The Stand. A rectangular table of mahogany, 18 in. by
10 in. superfices, and about an inch thick, constitutes the base
(A); to the surface of this is fastened a stout plate of brass,
of nearly the same size (B); near each corner of this is fixed
a brass column (C), a little more than an inch diameter, and
31 inches high. The fourgolumns support a stout brass plate
(D), 15 in. by 74 in., on which stand four smaller columns 12
inches high (£), they support another stage (/) 10 in. by 4
in., to which the principal part of the mechanism is attached.

The Mechanism: First Machine constructed in 1852. In
the simplest form of the machine, a vertical rod connected
near its superior extremity (G, fig. 1), with the upper brass
plate (F, fig. 1), and extending from it nearly to the base,
constitutes a simple lever of the first kind (G H, fig. 1),
whose arms are in the ratio of 1: 125 nearly. The rod tapers
downwards, its diameter diminishing from an inch to a quarter
of an inch, or thereabouts: this form of rod has been found
the most steady and least liable to tremor. It is connected
.with the upper stage (#’) by means of two concentric rings :
_the outer one (Z) is firmly fixed to the brass plate: the inner
_one (J) is connected by horizontal pivots with the outer ring,
-and with the vertical rod (G); the axes of the two pairs of
- pivots being at right angles to one another: by this connexion
rectilinear motion in one direction is permitted by the move-
“ment of the rod (G) on the pivots of the inner ring (J), a
-similar motion at right angles to this is effected by the move-
ment of the inner ring (./) on the pivots of the outer one (J) ;
by a combination of movements determined by the two axes,
motion in any direction, rectilinear or curved, is attainable.
_ Every movement of the lower end of the rod (#) 1s repeated
by the other end (G’‘), diminished in extent, and reversed in
direction. With a machine thus constructed, the diminishing
power is about 125 times, linear ; that is to say, a line one inch
in length traced by the lower end of the rod, will give at the

Machine for Microscopic Writing. o7

other end a line only 1-125th of an inch long, so that the
space occupied by any writing executed with this machine
will be 125? or 15,625 times less than that in which the writing
is traced by the hand.

Fig. 1. Fig. 2,

s-
Y.-
H--
\V---
\V--
Se
U-

In the present form of the machine, its power is much in-
creased by the substitution of a compound lever (G //, fig. 2)
for the simple one just described. This is done in the following
manner :—The original rod having been cut through a little
above the first stage, the lower portion is attached by its upper

58 Machine for Microscopic Writing.
end (’) to the brass plate (D) by two concentric rings (LZ M)

in the way already described ; the upper portion (G) remains
attached to the upper stage (F ) as at first, but is shortened by
cutting off a piece from its lower end (JV) : into the space thus
caused between the two parts (VV &) of the original rod, there
is introduced a piece composed of two short rods (P O and
O Q), united by a universal joint (O), similar to those by
which the two portions of the vertical rod are connected with
the two stages. Hach of the free ends (P and Q) of this
jomted member is made to slide truly and. smoothly in bear-.
ings supplied to the cut ends (K and NV) of the divided red,

so that the position of the joint (O) may be varied at. will: ae
place having been determined, it is fixed by means of a screw
(#), the end of which is made to press against one of the
sliding-pieces (O Q); and now, instead of a single lever con-

sisting of a simple vertical rod (G H, fig. 1), there: are two |
levers (G O and O #, fig. 2) united by a moveable joint (QO).
The first lever, extendine from the base of the stand to the
joint, has all that portion below the pivots on which it is sus-
pended for its long arm (K /), while its short arm (K O)
extends from the same pivots to the joint (O), and varies there-
fore in length, which is determined by the position of the
joint. The second lever, extending from the joint (O) to the
upper end of the combination (Z ), has for its short arm all
above the pivots connecting it with the upper stage; its long
arm (G Q) consists of the portion between the same pivots
and the moveable joint (Q), the position of which determines
the length of that arm. Thus it is seen that the short arm of
the first lever (J O) and the long arm of the second one (O G), -
vary in length with different positions of the moveable joint,
while the effect of their altered relations is always in the same:

direction.

With this combination, any movements of the lower end ae 3
the rod (H, fig. 2) are repeated, the direction reversed, and the
extent diminished, at the end of the .short arm of the first
lever (O), that is at the joint; the motion is there transferred
to the long arm of the second lever, at the end of the short
arm of which (Z ), the direction is again changed, and the ex-
tent a second time diminished.

The amount of diminution which the machine is capable of
effecting, ranges from 110 to 6,250 times linear: these limits
are determined by actual trial ; thus, if a square be drawn, the
sides of which are 5 inches long, the length may be reduced
to the 122-nd of an inch, that is 110 times, or it may be dimi-
nished to 1-1250th of an inch, or 6-250 times. An arrange-
ment of the levers, such that the arms are in the ratio of 12: |

Machine for Microscopie Writing. | 59
for the first (HK: K O),and 9:1 for the second(O G: G Z),

will diminish 108 times linear; an arrangement in which the
arms of the first lever are in the ratio of 500: 1, and those of
the second as 12: 1, will have the power of diminishing 6,000
times linear; and though it is not easy to determine exactly by
measurement the effective length of the different members of
the combination, it is believed that these proportions are not
far from the truth. By these adaptations, the transmission
and diminution of motion are provided for.

Contrivances for controlling and directing the movements, are
next to be noticed. It is manifest that the free end (/7) of a
lever suspended in the way described would move in the are
of a circle: to obviate the inconvenience of writing on a con-
cave surface, and at the same time to provide for a greater
freedom of motion to the pen or pencil, the lever is continued
to the surface of the base of the stand by means of a rod (S),
which passes into the lower end of the suspended tube (2),
and is connected with a second short rod (7 U) by two pairs
of rings (V), each pair joined together in one plane, and all
moving on horizontal pivots, so as to maintain exact parallelism
of the two rods, while the second one (7Z' U) is allowed to
move freely in a vertical direction: the second rod has at its
lower end a joint (UW), connecting it with a short arm which
carries a split tube (W) for holding a pen (X ) or pencil ; by
means of this joint the pen may be. made to have any inclina-
tion from the perpendicular; an adjustment in azimuth may
be made by turning the rod (S) in the vertical tube (#7): if
may be fixed in any position by a’screw (Y) brought to press
against it: this arrangement allows the pencil to move freely
over every part of a surface of about 5 inches square, within
which space it is perfectly under control, and on the surface of
which any writing or design may be conveniently traced.

A brass frame about 5 inches square is attached to the centre
of the plate which covers the base of the stand, by four screws
with milled. heads, one at each corner; after loosening these
screws, a card may be placed under the frame, and the screws
being then tightened, it is held firmly in its place without any
further attention on the part of the person using the machine.

Registry of the diminished design. “Tracie of the dimi-
nished movements are received on glass, that Asaierial afford-
ing the greatest facilities for the use of the microscope in
examining them. The distal extremity of the combined levers
is Gucnetore armed with a diamond point, and in order that it
may act upon the upper surface of the glass, the vertical rod
is connected with one end of a horizontal arm (A), from ‘the
other end. of which a piece (jp) at right angles to. it rises to

60 Machine for Microscopic Writing.

the height of about 3 inches; the upper end of this piece is
split to receive another horizontal arm (a), at the free end of
which is the diamond (d), with the point downwards, and so

Fig. 3.

adjusted that it is in the axis

_ of the combined levers.

As, however, the end to
be attained is the registering
(not of all the movements
made, but) of those move-
ments only which form the
writing or design, the opera-
tor is provided with the
means of suspending, resum-
ing, or continuing the action
of the diamond at pleasure.
Two uprights (1, fig. 3 and
fig. 4) are fixed near opposite
edges of the upper stage
(F’), each having a borizon-
tal pivot (or they may be
connected by a_ horizontal
piece with a knife edge up-
wards): on the pivots (2),
(or the knife edge) is hung
a thin flat plate of brass (3)
of sufficient size to hold a
glass slip of the ordinary
dimensions, 3 in. by 1 in. ; to
one of its ends is fixed a
steel wire (4) with a screw
cut upon it, on which a small
brass weight (5) with an in-
terior screw is placed: near
one of the lateral edges of
the plate two small pins (6,
fig. 4) project a little above
its surface: near the opposite
edge is a spring (7, fig. 4),
which presses the glass slide
against the two projecting
pins, while one of its ends
comes up to the extremity

of a screw (8), which can be adjusted so that the centre of the
glass be brought under the diamond point (Z): when the slide
has been placed on the holder and properly adjusted, the weight
(5) is to be moved on the ‘screw till it accurately balances the

Machine for Microscopic Writing. 61

glass, which should just touch, but not be pressed against the
diamond. Under the glass holder (3) is a weak spring (9)
attached toa short arm (10), which is connected by a hinge with
a little pillar (11) fixed to the upper stage (/’); under this arm
is another shorter but stronger spring (12), which, yielding to
the action of any force depressing the arm (10), restores it to
its place on the action of the force being discontinued. From
the free extremity of this arm a wire (18) proceeds to the base
of the stand, where it is fastened to a lever (14), which is at-

tached to the lowest brass plate (B) by a hinge (15), which

Fig. 4.

J

allows of motion only in a vertical direction: when the end of
this lever (14) is pressed down, it draws down the extremity
of the arm (10), carrying the spring (9) which is then brought
to act upon the glass holder (3), pressing the glass upward
against the point of the diamond (Z); a spring (16) under
the lower lever (14) causes it to return to its position when
the pressure is removed. Two screws (17, 18) pass through
this lever, by means of which the extent of its movements,
and consequently the pressure of the spring (9) under the glass
holder (3) are regulated. One of these screws (18) serves to

62 Machine for Microscopic Writing.

limit the upward movement of the lever: this is effected by
means of a moveable nut (19), above the arm, which can
be placed in any required position; the other screw (17) is
for regulating the pressure against the diamond ; it admits of
its end (20) being fixed at such a distance from the brass plate
(B), as to allow of any required extent of depression of the
lever: it is obvious that the more this is depressed, the lower
does it draw down the arm (10), carrying the spring (9), and
the stronger therefore is the pressure of the spring against the
glass: By connecting a second lever with the spring, and
allowing one to be dept essed more than the other, two different
degrees of pressure against the glass may be secured, and the
diamond may thus be made to give marks of different depth
and thickness, so that writing may be produced with fine up-
strokes and thick down-strohes, as in writing with a pen.

It is unnecessary to do more than allude to the excellence
of the work, and the perfect action of the mechanism. These
are manifested by the fidelity with which the smallest move-
ments are transmitted and recorded, every such movement, it
will be remembered, having to be ‘transmitted through three
joints with two sliding-pieces ; each of these joints must
admit of free and easy motion in every direction, while all
tremor, or other movements than those directed by the will of
the operator, must be precluded. How completely the
object is accomplished is within the personal knowledge of
many gentlemen present who have themselves had the oppor-
tunity of testimg the capabilities of the machine. Were other
evidence necessary, reference could be made to the eminent
President of this Society (Dr. Carpenter), who, on a first trial
of the machine, produced an inscription of three lines in less
than the 1-10,000th of a square inch. Of this space the
signature takes up not more than one-third, or less than
1-30,000th of an inch; the small letters of the writing are
but 1-1150th of an inch high; yet, notwithstanding its
minuteness, the characteristic peculiarities of the autograph
are unmistakable.

The securing of a good diamond point is a matter of first
importance : preference 1 is given toa turned point, as a natural
splinter, though it gives fine strokes, does not mark equally
well in all directions. These points Mr. Peters prepares
himself with the same skill and delicacy of touch shown in
the construction of the other parts of the machine.

In using the machine both hands have to be employed.
While the right hand guides the pencil (X), the other is en-
gaged: in managing the lever (14) by which the action of the
diamond is governed. A'ttention is necessary to’ insure the

Tlumination of Objects by Polarized Light. 63

requisite pressure when any movement is to be registered, and
to withdraw it while any other. movements are in progress ;
for it must be remembered that all movements made by the
pencil, whether there be corresponding marks on the card or
not, are traced on the glass so long as it is pressed against the
diamond ; and, on the other hand, though the design be care-
fully and accurately marked on the card, there will be no
trace of it on the glass anion the lever has been properly
employed.

The object of this paper is to give a brief, but it is hoped,
an intelligible account of the construction and manner of
using a machine which has excited much interest, and not to
consider the purposes to which its ingenious adaptations may
be applied. At present the machine has been used almost
solely for microscopic writing ; it is not, however, to be con-
cluded that it can be used for nothing else. If, for example,
the pencil, mstead of being guided by the hand only, were
directed and restrained by mechanical appliances, and the
amount of the movements regulated by a screw or otherwise,
there seems no reason why the preductions of Nobert should
not be rivalled. ‘There would be little practical difficulty in
causing the pencil to trace straight and parallel lines: regular
distances of 1-100th of an inch are attainable. The power of
the machine would diminish these intervals 6,000 times, so
that a series of lines 1-600,000th of an inch apart would be
attainable. Whether a point could be got sufficiently fine to
trace lines so close together, or any surface to receive them,
may be questioned. If, however, such close ruling as this is
impracticable, the limit would seem to be supplied by the
want of a material to receive the tracings, and not to result
from the insu fliciency of the machine to execute the movements.
Perhaps the machine might be made subservient to accurate
dividing in the preparation of micrometers, &c., as by its
means, errors or inequalities admit of being almost indefinitely
diminished.

On the Ittumrination of Oxsects hy Potarizen Lieut on a
Darx Frecp. By Joun Furze.

(Read April 24th, 1855.)

ALLow me to call the attention of the Society to a method of
viewing objects with the microscope, which is, I believe, novel
in its arrangement, and no doubt admits of oreater improve-
ment than it has yet received at my hands, fait the want of
sufficient time and opportunity to devote to that purpose.
The phenomena of polarized light have long added a charm

64 Illumination of Objects by Polarized Light.

to the ordinary developments of the microscope; and the
brilliancy of colour resulting from its action has fixed the
appearance of many an object in the mind of the observer,
which, by ordinary light, would have made scarcely any mental
impression at all.

But with the advantage of attractive appearance two great
defects were constantly perceptible: one, the impossibility of
transmitting the light through structures of more than a cer-
tain density ; the other, that although the differing densities
of structure were separated by it, the definition of these were
disfigured in some cases, and /ost in others.

t therefore became obvious that if objects could be illu-
minated by polarized light, in such a manner as to give the
structure a stereoscopic effect, by a due contrast of light and
shadow, causing the object to appear as if in relief, great
benefit would result from the application, as giving a clearer
development of the form and constitution than had before been
obtained. This expression at once suggests the dark-ground
illumination, which some of our Members have so largely im-
proved by various useful adaptations. I have found it pre-
ferable to use for this purpose a plano-convex lens, three-fourths
of an inch in diameter. This fitting is of sosmall a size that it
can be adapted to almost any instrument. An illuminating lens
thus constructed will show intended objects on a black ground
through the low powers, and should be arranged with a
system of both central and external stop, each revolving on a
separate axis, as generally supplied. If we now put an ad-
justable cap on to the top of the lens, containing a crystal of
Herapathite mounted between thin glass, and a plate of Selenite
(also mounted on thin glass) above it, we shall find that ob-
jects of too great density for transmitted light, will appear,
under this illumination, as if in relief; and not only will the
varying density of the structure be most beautifully displayed,
but the definition of the different parts will be so accurately
given as to constitute a perfect method of viewing the object.

I do not profess to write a long article to engage your
attention here; but I would fain occupy some portion of your
time at home in perfecting this arrangement, which, in my
Opinion, is most conducive to truth in microscopic analysis,
and which will amply reward (as well in the highest as in
the lowest sense) the careful labours of those who sympathise
with me in the delights arising from those researches which it
is the peculiar province of this Society to encourage and to
stimulate.

REPORT
7
THE FIFTEENTH ANNUAL MEETING

OF THE

MICROSCOPICAL SOCIETY.

Tue Microscopical Society of London held their Fifteenth
Annual Meeting, February 28th, 1855,—Dr. Carpenter,
President, in the Chair. The Assistant Secretary read the
usual Reports of the Council and Auditors, which showed
the Society to be in a very satisfactory state of progress: the
balance-sheet is given on the following page. The ballot
then proceeded for the officers for the ensuing year.

Re-elected.
President . . . . Dr. CARPENTER.
Treasurer’: -. . N. BJ Warp, Esq.
Secretary . . . . J. QueEKeETT?, Esq.

New Members of Council.

J. N. Furze, Esq.

H. Periear, Jun., Esq.
Rev. J. B. ReEApE.

J. B. Stmonps, Esq. .

In the place of
G. Bienxins, Esq.
Dr, LANKESTER.
G. SHADBOLT, Esq. 3
J. Inapen, Esq. (deceased).

The President then delivered the Annual Address, reported
at page 37.
VOL, II. F

Fifteenth Report of the Microscopical Socvety.

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TRANSACTIONS OF MICROSCOPICAL SOCIETY.

DESCRIPTION OF PLATE II.

of Diatomaceous Forms.”

The figures here given do not represent all the forms which may prove
to be referable to Navicula varians, as described in the ‘ Transactions,’
but are intended to show several of the more striking types, as well as
some of the many transition forms by which these appear to be connected
together.

"Thus, starting from fig. 1, which, as well as fig. 14, has the aspect of
Pinnularia oblonga much shortened; we find that in fig. 2 it becomes
larger and broader, and in fig. 4, still larger and longer, retaining the
broad obtuse apices, while it acquires something of the character of P.
peregrina. In fig. 6, it is again shorter and broader ; but in figs. 3, 3, 5,
5b, and 7, we observed it becoming narrow, sometimes rhombic, with
acute apices in 5 and 5 8, and a slight constriction in the others. In figs.
8, 9, and 10, the form is more elongated, especially towards the extremi-
ties; but in 100 and 11, it is again shortened, retaining however, the
constriction, which in fig. 11 is so strong as to render it subcapitate.
From fig. 11, figs. 12, 138, and 13, lead us to figs. 14, 15, which are, as
already stated, closely allied to fig. 1. This group includes forms either
identical with, or very similar to P. oblonga (shortened), P. peregrina,
and P. acuta. The resemblance to the latter species, however, in figs. 3,
3b, 5, and 5 8, is only in shape, the striation being quite distinct.

From fig. 14, we pass by fig. 25, which is shorter and more oval, to fig.
16 (Navicula scutelloides, Sm.), which is of a short, broad, oval form, and
sometimes almost orbicular. I have some doubts whether this last be
referable to N. varians, or even whether it be a Navicula at all: it is
understood that some good observers regard it as a Cocconeis. But I have
no doubt as to the propriety of classing figs. 14 and 25 together.

From fig. 11, we pass, in another direction, to figs. 24, 28, and 22,
which are all subcapitate or capitate; figs. 246, 21, 196, and 19, lead us
gently to figs. 18 and 18 b, and through these to fig. 17, which is more
decidedly apiculate than 186. ‘This last, fig. 18 b, appears to be identical
with the form described by me in the Mull earth as Pimnularia exigua.

From figs. 23 and 22, we are led, through fig. 20 to fig. 206, which
seems to be a variety of NV. inflata, fig. 20c. The latter is so well marked
a species, that it may be doubted whether it can be a form of N. varians.
I would not assert that it is so, but if figs. 20 6, and 20, are to be regarded
as varieties of LV. inflata, it is evident that that species is susceptible of
considerable modifications, and we have already traced the connection
between figs. 20 and 20 db, and others, which seem undoubtedly to belong
to N. varians.

From fig. 17, we now pass to figs. 27, 28, and 280, which are very
striking forms, some of which have been supposed to be referable to N.
Semen. But the striation in these forms is remarkably strong and con-
spicuous, while in N. Semen it is quite the contrary. Indeed, in Ehren-
berg’s Microgeologie, where the striation of many forms is well represented,
even where it is not easily resolvable, NV. Semen is figured without strie.

rom the last-named group, we proceed, by figs. 29, 29 0, to figs. 30,
30 6, 30c, and 380d, in which the type of form of Pinnularia gracilis
appears, more or less distinctly. But the conspicuous and somewhat
coarse striation at once distinguish these forms from that delicate species.
In fig. 38, this type is fully developed in all dimensions, producing a
splendid form; while in figs. 31, 32, 32b, and 32c, we pass through
various modifications to the form or type of Navicula rhyncocephala.
Want of space prevents the introduction of larger specimens of this type.

In these the striation is strong and coarse; but in the smaller it is not
far removed in character from that of the N. rhyncocephala of Smith, so
common in our fresh-water gatherings.

' In publishing these figures, and in the-paper which they are designed to
illustrate, my object has been to direct the attention of observers to the
existence of a large number of forms, very few of which have hitherto
been noticed or ficured, although they are of very frequent occurrence.
There is hardly a fresh-water gathering of a mixed character, in which
many of them are not found. But the only figured species which are
probably referable to this group are Navicula rhyncocephala, Pinnularia
peregrina, P. exigua, and possibly Navicula inflata.

I would by no means be understood as asserting that all these forms
belong certainly to one species ; but it is plain that most of them are
very much inclined to vary in outline, and thus, apparently at least, to
pass into each other, retaining all the time the peculiar character of
striation, and the aspect which marks the group. I must here add, that
even in the number of striz, and in one type of form, considerable varia-
tions occur. As the forms become larger, the striz decrease in number,
and become stronger and more conspicuous, so that no precise number can
be fixed on, as typical of the species. I have myself counted in some of
the smaller forms, 22 or 24 striz in ‘001 of an inch, while in the larger,
the number falls to 14, or even sometimes to 12. But this variation in
the number of striz in ‘001 of an inch is by no means confined to these
forms. It may be seen in many species, perhaps in all those which vary
much in size.

One more fact deserves to be noticed, as favourable to the idea that these
forms, at least in great part, are referable to one species. I allude to the
circumstance, that I have never found one of these types alone; but that.
several of them, in some cases nearly all, occur together.

The localities which best exhibit this fact, are Duddingston Loch, .
Lochleven, and the Dhu Loch in Glenshira, the recent mud of which is
rich in several of these types. A gathering from a brook near Oban con-
tains nearly all of them, and another from Norfolk, which I owe to the
kindness of Mr. Bleakley, also presents a large proportion of these forms.
But, as I have already remarked, they occur, more or less abundantly, in
almost every mixed fresh-water gathering.

This leads me to observe, in conclusion, that all the forms of that series
which appear to be identical with P. peregrina, occur abundantly in pure
fresh water ; whereas P. peregrina is described as a form of sea water, or
brackish water. The forms here described, having moniliform striz, should
be referred to the genus Navicula, if that character be regarded as decisive 3
of which doubts may be entertained. But as it appears, by the observa-
tions of the Rev. Professor Smith, that he found the strize of undoubted
P. peregrina to be, in some examples at least, moniliform, there can be
little difficulty in regarding this form as one of the types of Navicula
varians. At all events, the form or type alluded to, as I have found it
in Duddingston Loch and Lochleven, is one which varies remarkably in
outline and proportions.

The figures now given must be considered merely as intended to bring
under the notice of observers a very common, yet a very interesting, group
of forms; but not as, in any respect, exhausting the subject, or as esta-
blishing with certainty the view which regards all these types of form as
varieties of one species alone. That question cannot be decided without
more extended investigation. But at least the figures will show that
there is, in certain forms, a remarkable tendency to variation in outline ;
and I have already found that this tendency exists in a considerable num-
ber of species, to a greater or less extent. Farther observations will also
determine how far this tendency to variation extends, and whether it
affects, not only the outline, but the character or number, of the striz, the
appearance of the nodule or "of the median line, and the general aspect.

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TRANSACTIONS OF MICROSCOPICAL SOCIETY.

EXPLANATION OF PLATES III. AND IV.

N.B.—AII the figures are drawn under the same magnifying power,
save 2, 8, 4, and 9, which are much more highly amplified.
Fig.

1, (Plate III.)—One of the vitelline spheres or ova (there being then no
perceptible difference between them) from a newly-formed capsule.

2.—A small portion of the vitelline substance highly magnified.

3.—Vesicula directrix, apparently single.

4,—Vesicula directrix, double.

5.—Segmentation of vitelline spheres ; a, b, c, d, e, successive stages.

6.—Seementation of vitellus of true ova; a, b, c, successive stages.

7. (Plate IV.)—Mass of vitelline segments beginning to coalesce, but
torn apart so as to show an embryo, a, in the interior ; on either
side are embryos in various stages of development, found in the
same capsule, but not imbedded in the conglomerate mass.

8. (Plate II1.)—Early stages of development of embryo, up to the forma-
tion of the mouth and cesophagus.

9.—Ciliated mouth, as seen laterally at a, and from above at 0.

10.—Conglomerate vitellus, with attached embryos drawing-in its com-
ponent particles.

11. (Plate IV.)—Portion of a similar mass, with embryos, a, J, ¢, d,
attached, and others, e, f, detached, from the same capsule, of very
different sizes. ;

12.—Embryo having its transparent peripheral membrane speckled by
small adherent particles, resembling the vitelline particles in fig. 2.
This appearance is not at all uncommon.

13.—Three embryos, a, b, c, of larger size; their ciliated lobes obliterated
by distention.

14,—An embryo of unusually large size, with portion of conglomerate
vitellus still adherent.

15, 16.—More advanced embryo, with ciliated lobes and foot fully deve-
loped, and the newly-appropriated vitellus in process of conversion
into other organs.

17.—A small embryo, which has apparently only just began to ingest
its supplemental vitellus ; this being superposed upon the original
yolk-mass.

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TRANSACTIONS OF MICROSCOPICAL SOCIETY.

DESCRIPTION OF PLATE V.

Illustrating Mrs. Herbert Thomas’s Paper on Cosmarium
margaritiferum.

Figs. 1 to 33, illustrating various stages in the growth and development
of Cosmarium margaritiferum.

es

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INDEX TO TRANSACTIONS.

VOLUME

ile

ve

Address of President of Microscopical
Society, 37.

C.

Carpenter, W. B., F.R.S., F.G.S., on
the development of the embryo of
Purpura lapillus, 17. ;

,, Address at Annual Meeting
of Microscopical Society, 37.

Chemical and visual foci of object-
glasses, by F. H. Wenham, 1.

Coincidence of the chemical and
visual foci of the object-glasses, by
F. H. Wenham, 1.

Cosmarium margaritiferum, on, by |

Mrs. Herbert Thomas, 33.

D.

Development of the embryo of Pur-
pura lapillus, by W. B. Carpenter,
M.D., F.RS., F.G.8., 17.

Diatomaceous forms, remarkable
group of, by W. Gregory, M.D.,
F.R.S.E., 10.

Discovery of parasitic borings in
fossil fish-scales, by C. B. Rose,
F.G.S., 7.

EK.

Embryo of Purpura lapillus, develop-
ment of, by W. B. Carpenter, M.D.,
EURS.,. F.G-.S:, 17.

F.

Farrants, Mr., on Peters’ machine, 55.
Furze, Mr., on polarised light, 63.

G.

Gregory, W., M.D., F.R.S.E., on a
remarkable group of diatomaceous
forms, with remarks on shape of
outline as a specific character in the
Diatomacee, 10.

I

Illumination of objects, 63.

L.

Light, Polarised, illumination of ob-
jects by, Mr. Furze, on, 63.

M.

Machine for microscopic writing, 55.
Microscopic objects, photographs of,
1

Microscopical Society, address of pre-
sident of, 37; annual report of
Transactions of, 65.

Pp.

Parasitic borings in fossil fish-scales,
discovery of, by C. B. Rose, F.GS.,

Peters, Mr., machine for microscopic
writing, Mr. Farrants on, 55.

Photographs of microscopic objects,
by F. H. Wenham, |.

Remarkable group of diatomaceous
forms, by W. Gregory, M.D.,
F.R.S.E., 10.

Remarks on shape of outline as a
specific character of Diatomacec,
by W. Gregory, M.D., F.R.S.E.,
10

Rose, C. B., F.G.8., &c., on the dis-
covery of parasitic borings in fossil
fish-seales, 7.

ib

Thomas, Mrs. Herbert, on Cosmarium
margaritiferum, 33.

ANC

Wenham, F. H., on obtaining photo-
graphic objects, and the coincidence
of the chemical and visual foci of
the object-glass, 1.

TRANSACTIONS

OF THE

MICROSCOPICAL SOCIETY

LONDON.

NEW SERIES.

VOLUME IV,

LONDON;
JOHN CHURCHILL, NEW BURLINGTON STREET.
1856.

x

?

~

TRANSACTIONS

OF THE

MICROSCOPICAL SOCIETY

OF

LONDON.

On the Formation and DEVELOPMENT of the VEGETABLE CELL.
By F. H. Wenuam.

(Read November 28th, 1855.)

Tae favourable manner in which my paper on ‘Sap Circula-
tion,’ published in the last ‘ Journal of Microscopic Science,’
has been received, by some of tle most eminent members of
this Society, has encouraged me to bring directly before the
- present meeting the result of investigations on the origin and
first formation of the Vegetable Cell.

As I have admitted that I take up the microscope only
occasionally, as a means of recreation rather than a special
study, it may probably appear great presumption in one, com-
paratively unpractised, to make a statement of investigations
that stand in opposition to the opinion of the distinguished
observers who have written upon this self-same subject, after
many years of observation, aided by an intimate knowledge
of the researches of others in a similar department. I must
state, therefore, that I write with due submission, and in the
hope that some of the facts mentioned herein may contribute
towards the promotion of science, if only by directing atten-
tion towards a field of investigation, which, in my opinion, is
yet comparatively unexplored.

Feeling that many who take up the study of a particular
department of physiological science for the first time will
agree with me, I cannot refrain from protesting against the
excessive predilection that most professed writers exhibit, in
applying technical phraseology to a new branch of science
even in the earliest stages of discovery. From this mistaken
display of scientific pedantry, the uninitiated are probably at
first quite unable to comprehend the matter; and worse than
this, an inappropriate name is frequently applied to a circum-
stance or imaginary substance, having a doubtful, or at least

VOL. IV.

2 WennaM, on the Vegetable Cell.

not a very general existence, and this name is continued
throughout the whole series of subjects to which the science
relates, often giving rise to a maze of hypothesis. I make
the remark because the physiology of the vegetable cell is an
example of this, Let any one desirous of knowing in what
manner the cell is said to be first formed, take up the ela-
borate works on the subject by the continental writers, he will
find it there stated that an universal and necessary condition
of the existence of the cell is the first formation of a central
nucleus, termed the ‘cytoblast.” Around this is next
formed a membrane which eventually encloses the cell con-
tents, this is named the ‘primordial utricle,” and by the
division and duplication of this, successive cells are supposed
to be accumulated.

The primordial utricle is a necessary condition in the
anatomy of some unicellular plants, such as the Desmidiee and
Alya, for, in these instances, the folding inwards of this im-
portant membrane causes a constriction of the contents of each
cell, and a reproduction and multiplication by self-division ;
but the same analogy cannot be extended throughout the vege-
table kingdom, in those cases where a system of cells have a
mutual dependence upon each other. In unicellular plants
each cell is one in its most complicated condition, and
capable of continuing its existence as a separate plant, inde-
pendently of others, and is therefore provided with special
organs requisite for this peculiar mode of growth.

Those microscopists who, like myself, experience the most
fervent delight in reading a page directly from the book of
nature, may resort to their microscopes again and again in the
hope of witnessing the first creation of the vegetable cell, in
relation to the acting conditions of the cytoblast and pri-
mordial utricle. The search may be carried from tree, shrub,
flowers, or fruit, and be alike in vain. No direct ocular
evidence will be obtained of the existence of this nucleus and
membrane, and the attempt is abandoned at last, perhaps not
without some feelings of humiliation at the supposed un-
skilful manipulation, that failed to discover facts, believed to
have been firmly established.

Before proceeding to describe the formation of the vege-
table cell, I must premise that I am fully aware that the
interests of science are not to be promoted by controversy
based entirely upon mere hypothesis; I have, therefore, care-
fully avoided this. The illustrations were drawn directly
with the camera lucida in exact conformity with the originals,
and I have confined myself entirely to what I have seen; but
this course will not perhaps justify the assumption of a dog-

Wennam, on the Vegetable Cell. 3

matical position, for in microscopical investigation there is
some risk in even trusting solely to the evidence of eyesight,
and it frequently happens that a series of real facts may be so
arranged as to form the basis of a false theory.

In the last number of the ‘ Quarterly Journal of Microscopical
Science, I described an instance wherein I had observed the
growth and thickening of a cell wall to be caused by the de-
posit of a mass of active corpuscles, the so-called protoplasm.*
It is from this mysterious vital substance that all the cell tis-
sues of the vegetable world are built! The starch and chlo-
rophyll contained in the cell cavities, are also seen to derive
their increase of bulk by the deposit of the same material. If
any portion of a vegetable tissue (particularly if consisting of
a group of young cells) be placed in the compressor with a
very small quantity of water, and examined under a high power,
by applying sufficient force the mass will burst, and as the
protoplasm flows forth the following peculiarities may be
observed. It is not soluble in water, but only diffuses itself
therein; it is in all cases materially composed of active
particles, the size of which differ extremely in various
plants ; in some of the lower Cryptogamia, the particles con-
stituting the protoplasm are exceedingly minute, but with
a large aperture and good illumination the whole is still
seen to be chiefly composed of an assemblage of active
molecules.

Protoplasm, when flowing from the living plant into the
surrounding water, exhibits a remarkable tendency to separate
itself into cavities and ramifications, which speedily acquire
some degree of consistency, apparently from the formation of
a membrane, by the partial coagulation of the external
portion exposed to water. When the ramifications become so
much attenuated, as only to allow the passage of a few active
particles at a time, the lateral vibrations of these become
restricted, and they ‘travel some distance either backwards or
forwards, i in a manner very much resembling a single cur-
rent of sap in the living vegetable cell. At the point where
the cells have been ruptured, the protoplasm will sometimes
form a membraneous tube, through which the discharge takes
place.

Protoplasm exists in a dormant state of vitality in seeds
and dried roots, and many pollen granules appear to be simple
vesicles filled with this substance, the molecules being more
decidedly marked for partial drying. When a pollen grain

* The substance termed sarcode, composing the vital tissue of some of
the lowest orders of animals (such as Hydra viridis), bears a remarkable
resemblance, in some respects, to vegetable protoplasm.

b 2

4 Wentam, on the Vegetable Cell.

has been deposited in the plant ovule, the occurrence of a
cyclosis or circulation is said to have been discovered, passing
through the channel of communication that is formed between
the granule and embryo sac. This I have not yet witnessed.
Whether the protoplasm contained in vegetable cells is
endowed with the property of fertilization, I am not able to
affirm, unless the following circumstance can be taken as
evidence of the fact. During the conjugation of some of the
Alge and Desmidiee, the contents of two cells are expelled,
and first unite in the form of a shapeless mass; the accom-
panying protoplasm is now seen to extricate itself from inter-
vening particles, and envelope the whole of the ejected
endochrome with a gelatinous-looking sheath. All irregular
projections are next drawn inwards, and the mass acquires a
spherical or ovoid form. ‘The exterior of the layer of proto-
plasm is then converted into an investing membrane, and
finally a perfect sporangium is the result.

The point that I wish to direct attention to is this. If just
at the time that the combined masses of endochrome are
assuming the spherical shape, the lid of the compressor used
for the observation is repeatedly raised and lowered, so as to
wash away the investing layer of protoplasm, the mass of
endochrome will retain its ragged outline, without alteration,
for many successive days, and a sporangium will not be
eventually formed, thus showing that it is the living proto-
plasm that imparts the principle of vitality to the germ, and
also arranges the cell contents in the proper course of sym-
metry and order.

There are some remarkable movements of corpuscular
activity to be observed in some seeds, mainly due to the
presence of protoplasm. If a very thin slice of horse chest- |
nut is moistened with a small quantity of water, and covered
with thin glass, after about one hour’s duration the motion
will be in full force. The whole field of view is filled with
active granules of protoplasm, and also of starch, in all stages
of growth, the most minute of the latter being possessed of
molecular motion, ‘There are some spots in the fluid not to
be distinguished from the surrounding medium, either by
difference of density or any other indication, and which yet
cause a very peculiar action, for when the active particles
approach these places they are whirled rapidly past. Some-
times a molecule will suddenly start forward and shoot
straight across the field of view with considerable velocity,
dashing otbers out of its course. This oftentimes happens
when two have become adherent, and occasionally several
will be linked together in the form of a spirozoid, which

WenuaM, on the Vegetable Cell. | 5

screws its way through the water with a somewhat uniform
speed,*

Having briefly noticed some of the properties of proto-
plasm, I will proceed at once to the main subject of my paper.
I have selected the Anacharis Alsinastrum as one of the
subjects of investigation, chiefly on account of the magnitude
of the vital phenomena, and also becanse the perfect trans-
parency of the walls of the cells permits their internal move-
ments to be seen without impediment in the earliest stages of
growth, the action continuing under considerable mutilation

* Fearing that I am digressing too far from the direct title of this
communication, I append this note, submitting some further remarks on
corpuscular motion. When a single active molecule is in an isolated
position, its vibrations occur spontaneously and at random in all directions ;
but when a number are combined together in a line of narrow compass, if
they have a tendency to mutual entanglement or adherence, as in the
instance of the component gelatinous corpuscles of protoplasm, the longi-
tudinal vibrations are restricted, and the atoms are compelled to move
from side to side, or transversely. This occasions a waving or serpentine
movement of the thread-like current, which causes the whole to travel in
a straightforward direction; thus accounting for the circulation in the
vegetable cell. In some plant cells a thread of protoplasm, consisting of
a single line of particles, displays in its appearance such a remarkable
analogy to a single cilium, that I am inclined to consider the seminal fila-
ment, attached to some vegetable spores, as a simple line of conjoined
active corpuscles, the lateral vibrations of which cause the undulating and
progressive motions of the filament.

I cannot at present call to mind any instance wherein a strictly vegetable
cilium is possessed of a permanent existence. After its first temporary
office is fulfilled, as an organ of locomotion, for propelling the vital spore
40 another locality, it speedily becomes disorganised, and disappears.

On the other hand, the animal cilium, used either as a prehensile or
motile organ, is far more complicated. It is endowed with permanency,
and capable of renewal in cases of injury.

As a matter of conjecture, I offer a remark on those minute bodies
termed spizilla, or spirozoids, which are found in decomposing vegetable
and animal solutions. ‘They are sometimes so irregular in shape, length,
and bulk, that 1 suppose them to be merely associated particles of organic
matter linked together. If the component atoms are in a state of mole-
cular activity, the progressive undulations of the filament will cause the
helix to turn on its axis, and, in consequence, these corkscrew-like forms
advance through the fluid by rotation.

Jn the paper contributed to the last number of this Journal by Mr.
Busk, we are informed of the fact, that associated vital corpuscles in the
living animal possess the same tendency to travel in a direct forward
course as in the vegetable cell:—page 22: ‘“‘ A remarkable circumstance
observable in the spermatic cavities of Sagitta, is the continual cyclosis
performed by their contents. These will be seen constantly ascending on
the outer, and descending on the internal wall, or septum.” I have some-
times seen a cyclosis in the Hoftifera, in an organ which I presume to be
a spermatic vesicle; but this discovery, in a being apparently so highly
organised as the Sagitia bipunctata, is an important advance into the
mysteries of animal creation.

6 Wenuam, on the Vegetable Cell.

and distortion of form—a circumstance of particular import-
ance,

On dissecting out the centre of the bud at the extreme end
of a stalk of the Anacharis, a kind ef cellular cone will be
found, shown PI. L., at a, fig. 1; 66 are protuberances extend-
ing up the sides of the cone, being the germs of future leaves
in various stages of growth.

In the first formation of a leaf from the main stem, a small
nodule or protuberance appears, which is entirely filled with
granular protoplasm. A number of cavities next become
disseminated throughout the mass, as represented by fig. 2.
‘These are formed in the most random and irregular manner, both
as to size and position—small spaces being indiscriminately
mixed with larger ones of perhaps ten times their bulk, much
resembling the cavities in a slice of bread-crumb., ‘There is
no special means provided for the formation or arrangement
of these spaces, neither does it arise from any species of fer-
mentation, but from the inherent property that protoplasm
possesses of separating itself from its more fluid admixtures,
and forming cavities and thread-like divisions, as chance alone
directs.

At this primitive stage there are no travelling currents of
protoplasm, a feeble corpuscular motion is all that is to be
seen. ‘These cavities are the foundation of the cell formation.
Very minute starch granules make their appearance in some of
them, even at this period, as shown at a, a, fig. 2. This
example was drawn from the Anacharis, but it may be taken
as the representative of the primary cell formation of the
largest portion of the vegetable creation. The first germs of
either leaves, flowers, or stems, alike consisting simply of a
nodule of irregular diversiform cavities, so nearly similar in
shape and arrangement in widely-different species, as scarcely
to exhibit any distinctive features of variety, I have selected
the following plants to exemplify this :—Fig. 3 is a mass of
cells in their first formation, taken from the centre of a bud
of Arabis albida, with rudimentary cavities appearing in the
body of protoplasm at the apex. Fig. 4 is a leaflet from the
same plant, with the cells in a rather more advanced stage,
each cell containing a few minute nuclei, or incipient starch
granules. Fig. 5 is a malformed stellate hair, the base being
filled with protoplasm, which, in the upper portion, exhibits a
tendency to divide itself into cavities and cells. Fig. 6 is a
leaflet of Reseda, the apex having burst under the action of
the compressor, and the protoplasm had exuded into the sur-
rounding water, in the form of a globule, filled with cavities,
shown ata, a. This accident frequently happens, and may

Wenuam, on the Vegetable Cell. | ie

readily be mistaken for a mass of primary cell formation
Fig. 7 is the first formation of a linear leaf of the Anethum
Feniculum, bearing much resemblance to fig. 2.

Having shown the analogy between the primitive cell for-
mation of the Anacharis and non-aquatic plants, I wili now
trace the cell in its progressive stages of development, referring
from fig. 2, Fig. 8 represents the Anacharis cells in a more
advanced condition. A general longitudinal extension has
taken place throughout the mass, and something like a definite
line of cell formation becomes apparent. The cavities contain
an increased number of starch nuclei, and are now lined with
a distinct wall or membrane, but still, from the thickness of
-the intermediate substance, the whole structure resembles a
number of irregular vesicles or bags, imbedded in proto-
plasm.

If at this period of growth a portion of the leaflet be sub-
jected to the test of alcohol, the cellulose membrane lining
each cavity will separate, and shrink together upon the cell
contents. This has probably been mistaken for the so termed
primordial utricle; but however this may be, it is, in fact,
from first to last, the true cell wall, and is not dissolved or
absorbed in any subsequent state of the cell’s existence. It
thus appears that a bud, instead of starting at first from a
single cell, as some have imagined, derives its origin from the
simultaneous development of a group of some hundreds. The
number of cavities in the primary nodule do not exactly cor-
respond with the number to be contained in the perfect leaf,
for wherever there is an accumulated bulk of protoplasm, a
space is sure to be formed within it subsequently; new cells
are thus continually in the course of formation.

On considering fig. 2 it will become evident that if an
uniform distension of the mass should take place, the great
disproportion in the bulk of adjoining cavities would create a
system of cells, of such monstrous difference in size and
length, as to set all symmetry at defiance (well illustrated by
the extension of an india-rubber model). The manner in
which this difficulty is obviated, and regularity obtained at
last, is both simple and beautiful. Fig. 9 represents a series
of cells in a more advanced stage of growth. The walls are
yet soft, and much exceed their destined and final limits of
thickness. At this period cyclosis may be distinctly seen in
each cell, all of which now contain protoplasm within their
walls. In those cells that are exceedingly elongated, and dis-
proportionate in size, the protoplasm accumulates in the
middle, and forms a thick septum across, as shown at a, a, a,
thus dividing the cell into two. On beth sides of the septum

8 Wenuam, on the Vegetable Ceil.

a thin membrane is next formed, which constitutes the end
wall of the two cells. The two membranes gradually approxi-
mate towards each other, and the intervening protoplasm
disappears.

In instances where the cell is of excessive length, a larger
mass of protoplasm accumulates midway, in the centre of
which a cavity makes its appearance, as at a, fig. 10; this
enlarges, and becomes lined with a membrane, and thus di-
vides the original cell space into three parts,

A tissue of cells, in the stage of development represented
by fig. 9 is nearly colourless; it is about this period that it
begins to emerge out of its dark location, so far as to give the
first indications of the chemical action of light in causing the
deposit of chlorophyll instead of starch. The minute granules
of starch, previously scattered throughout the cells, serve for
the nuclei of the chlorophyll granules. At first they are enve-
loped in a delicate green coating, which becomes thicker, and
more decided in colour, as the cell approaches further into the
light. These incipient chlorophyll granules are now frequently
carried about in the currents of protoplasm circulating in the
cells at this time. A single atom of starch is sufficient for
the nucleus of a chlorophyll granule, but sometimes the green
coating is deposited simultaneously upon a group of several
together.

Fig. 11 represents the cells of a leaf of Anacharis in its
latest stage of vital existence. The cell walls having now
attained their utmost degree of thinness and consistency, the
entire leaf acquires a yellow tinge, from the altered colour of
the shrunken and partly dissolved chlorophyll granules (hence
termed “ xanthophyll’), which now so far disappear, that some
cells contain only two or three, much disintegrated. At this
period the leaf cells, though apparently in their first stage of
decay, are probably performing their most important functions,
by affording nutriment to the growing plant, by the dissolution
of their contents. In the specimen here drawn a rapid cur-
rent of protoplasm was traversing the interior of each cell.
This motion is perhaps quite as necessary for the solution of
the cell contents as for their formation by successive deposits ;
in fact, the phenomena of cell circulation are oftentimes best
seen at this stage.

I have omitted to mention that indications of a strong en-
dosmotic force are perceptible throughout the entire course of
cell formation. The cavities spontaneously formed in an
exuded mass of protoplasm sometimes burst from the accumu-
lation of fluid in their interior; many unicellular plants, after
being partly dried, will also burst on being again subjected to

Wenuam, on the Vegetable Cell. 9

moisture, from the infiltration of water into their cells. It is
this same force which is chiefly instrumental in causing the
distention of the detached vesicle or bag, of which each cell
primarily consists, till at last contiguous walls become united
throughout the structure. In some instances the force is not
sufficient to cause the complete distention and union at the
comers, consequently the leaf tissues of many plants are cha-
racterized by little angular spaces, occupying the point of
union between the confluent walls of neighbouring cells.

It now remains to be asked, if the first origin of all parts of
the vegetable structure consist merely of a protruding nodule
of protoplasm, containing numerous cavities in size and _ posi-
tion most irregular, what is it that determines whether this
shall form either a stem, flower, or leaf at last, the first forma-
tion being alike for each? The question is a difficult one to
answer in all its details, but it may be stated with certainty
that the primitive mass possesses no inherent power of its own,
in either shape or substance, to arrange its destined form of
growth. This is dependant entirely upon the influence of the
adjoining, and more perfectly developed portions of the plant.
In the case of a leaf, the soft cellular mass, while yet growing
in the bud, is moulded to something like its proper form by
the pressure of other leaflets, and when the cells of the embryo
leaf have acquired some degree of consistency, a single spiral
duct * is seen to grow out of the parent stem, forcing its way
as an axis through the soft assemblage of cells. Others quickly
follow, and lateral ramifications extend themselves as form
requires. In the case of a leaf, all this may be very readily
observed, but the formation of a flower-bud involves far more
complicated conditions, with the whole details of which I do
not profess to be acquainted. Fig. 12 will, however, serve as
an illustration; it is a group of embryo fiowers, taken from
the Arabis albida, during the month of October (the fully
developed blossom not appearing until the ensuing spring):
ais a simple protuberance, filled with protoplasm, in its early
stage of cell formation; 6 is a flower-bud, at a more ad-
vanced period of growth, the centre being permeated by
several spiral ducts and vessels. In the stages c, d, and e the
ducts and vessels are still to be discerned, but very much in-
creased in number and complexity; fand g exhibit all the
rudiments of the perfect flower, being apparently made up of

* It has not been explained very clearly how these vessels are formed.
By frequently observing their growing end among a mass of young cells,
I have imagined that I have detected a disc-shaped cell at the extremity,
by the successive formation and subsequent perforation of which the spiral
duct is formed; but the first growth is so indistinct and ill-defined, that
I cannot at present affirm it with certainty.

10 Wennam, on the Vegetable Cell.

thickened and gelatinous-looking masses of cells; A are cell
prolongations, or the successive rudiments of stellate hairs.

I may remark, in conclusion, that I am aware that some of
the facts relating to vegetable growth herein mentioned are
not new, but information on this subject exists in so scattered
a form that there is some difficulty in making special references.

Addendum.

In order that there may be no misapprehension of m
views, with respect to cellular creation, I append the following
summary of the succeeding stages :—

The first appearance of the formation of vegetable cells is
a simple protuberance filled with protoplasm, alike throughout
in substance. This is enclosed by askin or membrane, the
origin of the future leaf cuticle, but which, I presume, at this
early period, would be termed the “ periplast.” A number
of irregular cavities (vacuoles), filled with watery cell sap,
now make their appearance. ‘These are simply formed by -
the separation and agglutination of the viscous protoplasm.
A thin lining membrane is next developed in the interior of
each cavity ; this does not become detached at any after
period, but is, in fact, the imner stratum of the future cell-
wall. . ‘The membrane is thickened into a true cell-wall by the
direct transmutation into cellulose of the protoplasm existing
between, and exterior to the cell cavities.

It is not until the cell-wali has advanced to a well-marked
degree of development that any protoplasm is generated within
the cell. This now rapidly makes its appearance, and spreads
itself within the cell-wall. Hence arises the question whether
this, when in the form of an internal layer, is explicitly un-
derstood if termed the “ primordial utricle?” In this case
primordial is certainly inapplicable, because protoplasm does
not make its appearance in the cell cavity before it is some-
what advanced in growth, and sometimes is not even seen,
until subsequently to the formation of minute starch granules
adherent to the cell-walls.

By the application of a reagent, the protoplasmic layer,
from being extremely prone to coagulation, can be made to
contract like a membrane upon the cell contents, but I ques-
tion whether the term membrane, or utricle, is to be properly
applied to a motile but viscous fluid, which at times will run
together in patches and clots, and leave large portions of the
cell-wall bare. There is perhaps no reason against the pro-
priety of the term when applied to some unicellular plants, in
which the appearance and uses of such a membrane are so
distinctly to be observed.

uM
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Ae By fe ends

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Micro. Trans., Vol. IV., Pl. dl.

laa

A Simple Form of PorrastE Mrcroscorr, with Lever
ADJUSTMENT, which may be adapted to several different pur-
poses. By Lionet Beatz, M.B., Professor of Physiology
and General and Morbid Anatomy in King’s College,
London.

Tue Microscope which I wish to bring under the notice of
the Society, seems to me to possess some advantages over
those in ordinary use in simplicity of construction, in the
number of uses to which it mav be applied, and in price.
The accompanying outline diagrams show the general ar-
rangement of the instrument. The telescope stem, a, and
horizontal arm, 6, upon which the body, c, is fixed by the aid
of a hinge-joint, e, are made of brass tubes, about an inch in
diameter. Upon the outside of the stem the stage, f, and
mirror, g, are made to slide. The lower part of the stem
slides in a tube, h, provided with a clamp screw, 7, so that
the whole instrument may be arranged in the erect posture at
any convenient height, Fig. 1, Pl. If. If required, the mirror
can be fixed upon the lowest part of the stem beneath the tripod
at k, The tripod stand may be made of cast iron or of brass,
and each leg attached with a hinge-joint, which increases its
portability. The horizontal bar is prevented from turning
round by a ridge, /, which is fixed upon its lower surface, and
which slides in a groove in a piece of tube attached to the
upright by a hinge-joint, m. The coarse adjustment consists
of a knee-lever, n, and in this way a very smooth and steady
movement of three inches in extent is obtained. The tube in
which the body slides should be longer than that in the instru-
ment exhibited this evening. For the adaptation and manu-
facture of this lever adjustment [ am indebted to Mr. Becker,
Philosophical Instrument Maker, of Newman-street. A fine
adjustment may be attached in the usual position, just above
the object glass, 0. Upon the front of the body, in its upper
part, is placed a small piece of brass, with a number of holes,
p, m which a small brass pin may be inserted, so that the
object-glass may be brought as close to the object as may be
desired, and at the same time without any danger of its being
forced down upon the object, or through the glass slide
placed upon the stage.

Fig. 1 shows the instrument arranged in the erect posture.
Fig. 2 ina slanting direction. The horizontal arm, 0, in this
position takes the place of the upright stem. Fig 3 repre-
sents the microscope arranged for making minute dissections,
a small pin, 7, prevents the horizontal bar from falling too

VOL. IV. c

14 BEALE, on a simple form of Portable Microscope.

low. In fig. 4 the telescope tube is drawn out, and the in-
strument arranged for examining living animals, &., in a
vivarium.

The various portions of the microscope are readily sepa-
rated from each other, and can be packed in a small case.
The weight of the entire instrument, with case, &c., will
probably not be more than six pounds. Mr. Matthews, of
Portugal-street, Lincoln’s Inn, thinks that this microscope,
without powers, can be well made for five pounds, or even
less. There is some vibration in the body of the mstrument
which I have in use, but the lever movement appears likely
to answer well for all powers below half an inch; the motion
is even smoother than would be supposed. Several slight
alterations in the mechanical parts of the instrument have
been suggested, and will doubtless add to its efficiency. As
a travelling microscope, especially for sea-side work, this
arrangement will I think be found very useful, and is not likely
to get out of repair.

Micro. Trans., Vol. IV., Pl. III.

Fig, 4.

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OR OL ee mr FEAR AIT, dite el PERRO rae 5 a

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REPORT

OF
THE SIXTEENTH ANNUAL MEETING

OF THE

MICROSCOPICAL SOCIETY.

Tue Meeting was held February 27th, 1856,—Dr. Carpenter,
President, in the Chair. The Assistant Secretary read the
following Reports :—

According to annual custom, the Council have to make the
following Report on the state and progress of the Society
during the past year.

The number of Members at the last Anniversary, was 221,
including 6 Associates and Honorary Members. Since that
time there have been elected 32, making a total of 253. This
number must, however, be reduced by 3 deceased and 9
resigned, making a final total of 241; still showing an
increase of 20 upon the number at the last Anniversary.
Many new works and objects have been added to the Library
and Collections of the Society. There are also in the posses-
sion of the Society various drawings and diagrams relating
chiefly to papers read at the Meetings, together with copies
of the several parts of the Transactions and of the Journal.
The state of the finances of the Society will be shown by the
following Report of the, Auditors, from which it appears that
there is a balance in the hands of the Treasurer of 371. 14s. 4d.

The election of Officers took place, when the following
gentlemen were elected :-—

Officers and Council.

mreident . .-. . GEO. SHADBOLT, Esq.
Dreasrer. . 1. INS Be, Warp,, Esq.
Secretary . . . . J. Quexert, Esq.

Four new Members of Council.
Dr. LANKESTER.
F.S. C. Rover, Esq.
R. J. Farrants, Esq.
Antonio Brapy, Esq.

In the place of
G. C. Hanprorp, Esq.
R. Hopeson, Esq.
Rev. J. B. Reape.
F. Srmonps, Esq.
who retire. «2

Sixteenth Report of the Microscopical Society. -

16

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(hrs

Address of the PREsiDENT.

GENTLEMEN,—The circumstances under which our Society
now meets, bear so close a resemblance to those which ex-
isted at its last Anniversary, that we must look upon them, I
think, as representing, not a transient condition which it may
be left to time to modify, but a persistent state which has
grown to be a part of our existing constitution. I think it
well, therefore, to place before you, in the best manner I am
able, such an honest view of our position as may bring out
our weak as well as our strong points, our deficiencies as well
as our advantages; and may thus at once suggest remedies
for the former, and lead to the still further development of
the latter.

Our Report is again most satisfactory in regard to the
financial position of the Society. The number of members
still continues on the increase, no fewer than thirty-two new
members having been elected, whilst we have lost only twelve
by death or withdrawal. Our funds have consequently been
adequate, not only to supply every member with a copy of
the ‘ Quarterly Journal,’ but also to furnish tea for our meet-
ings; and we have also been able to meet without inconve-
nience an unexpected demand for an arrear of twelve guineas

due to the Ray Society. |
- Our meetings, also, have been almost uniformly well
attended ; and great benefit has doubtless resulted from the
intercommunication which they have promoted between so
many who are interested in the same pursuit.

We are far, however, from having similar cause for satis-
faction, in regard to the number or the importance of the
papers brought before us. The dearth which I last year
hoped might be temporary, has increased rather than di-
minished ; and our meetings would have been without any-
thing to occupy them, on several occasions, if means had not
been extemporaneously found for supplying the deficiency.
Our Transactions for the last year contain but two papers and
one short notice; and these, with a paper which it was not
thought desirable to include in them, and with the exhibition
of Mr. Warrington’s and of Dr. Beale’s new forms of micro-
scope, constitute the whole of the regular business which has
come before us.

Now I cannot but regard the continuance of this state of
things as likely to be most prejudicial to the interests of the
Society. It would be unreasonable to expect that the attend-
ance at our meetings should keep up, if there be no adequate

18 Address of the PRESIDENT.

prospect of materials for their occupation. That which should

be but a subordinate inducement to membership of the So-
ciety, the title to receive its publications, seems now to have
become the principal attraction ; every member, through the
arrangement which we have been enabled to make with the
proprietors of the ‘ Microscopical Journal,’ having nearly
three-fourths of his subscription returned to ‘him inthis form.
But this arrangement may be determined at any time 3 since
it merely exists so long as it shall be found to work advan-
tageously for both parties. If the proprietors of the Journal
should have reason to think that the increase in the number
of our members causes a diminution in the number of their
subscribers, they will probably not consider its continuance to
be for their interest; whilst, on the other hand, if it should
appear that the support which we give to the Journal, so far
from promoting our welfare as a Society, has an indirect
tendency to weaken us, that support we might feel it desirable
to withdraw.

I cannot but consider that both the status of the Society as
a scientific body, which must depend upon the goodness and
quantity of the work it does, and the maintenance of its attrac-
tiveness and efficiency as a centre of union to those engaged in
microscopic research, necessitate the taking of some steps to
supply a deficiency which has now become unfortunately but
too apparent; and the first and most obvious of these steps
consists in the inquiry into its causes. Of these, I shall oaly
specify what occur to myself; others will doubtless be sup-
plied by such as have a more extended acquaintance than I
possess with the individual members of our Society.

In the first place, | am disposed to think that the facility of
publication now afforded by the ‘ Microscopical Journal,’ has
had no inconsiderable influence in diminishing the nuimber of
papers sent to the Society.

Formerly our Transactions constituted the only medium
through which a microscopist could readily make public,
with the requisite illustrations, such results of his inquiries as
might scarcely possess the dignity or completeness required
for presentation to the Royal or Linnzan Societies. But the
Journal now opens its pages freely to all, whether Members
of this Society or not; its editors readily admitting every
creditable paper, and liberally furnishing the requisite illus-
trations. Now as our Transactions are published in a form
so precisely similar to that of the Journal, as only to be
distinguishable by the numbering of the pages, few authors
would much care whether their contributions appear in
one part of the Number or the other. And yet there is,

ee

°s

Address of the PrestpENT. 19

or there might be, a considerable difference in the credit

attaching to these two appearances respectively. For the
editors of the Journal (having to fill a certain number of
pages every quarter) can scarcely be expected to feel that
responsibility as to the quality of the papers they insert,
which lies upon the Council of our Society, which is charged
with admitting into its Transactions only such communi-
cations as they may deem possessed of a certain scientific
value. As the case at present stands, I cannot but believe
that the want of due appreciation of the superior credit of our
Transactions, and a feeling of indisposition on the part of
authors to subject their communications to the double ordeal
of a public discussion and of a privately-considered verdict,
have kept, and will continue to keep, many valuable papers
from being brought before the Society.

Now if such be really one of the causes of deficiency, the
next question is, how can it be remedied? ‘The remedy does
not seem to me to be easy, so long as the existing union
between the Transactions and the Journal shall continue ;
and this union is attended with so much advantage to our
Members, that I cannot advise its discontinuance. But it
has occurred to me that a more marked difference might be
advantageously made between our ‘Transactions and the
Journal, by adopting a different style for the former,—a some-
what larger type, for example, or a more open page,—which
should in some degree mark the superior status which I]
claim for them. The remedy lies essentially, however, with
the Members themselves; who ought, I think, to feel under
an obligation to promote the interests of the Society, by
sending their communications to it, rather than forward them
direct to the Journal: and though we can scarcely exert any
compulsion in such a matter, yet | would have the latter pro-
ceeding discouraged, and the former encouraged, by the potent
voice of public opinion. Further, if we can, by such a dis-
tinction as I have suggested, increase the value set upon the
appearance of a paper in our Transactions, we might take
means to attract to ourselves various communications from
sources external to our Society, which at present naturally
follow the course of the stream that carries them to the
Journal,

Another source of the deficiency in question, appears to
me to lie in the desultory mode in which a large proportion
of our microscopic observers apply themselves to the use of
the instrument. When we contrast the products of British
and of German microscopy, and see how completely inverse
are the proportions between the values of the instruments em-

20 Address of the PRESIDENT.

ployed, and of the results obtained, in the two countries
respectively, we cannot but feel some shame at the low position
we take. Now it may be said, that there are so many more in
Germany who can make microscopical observations a special
object of pursuit, devoting to it a large proportion of their
whole time, than there are in this country, that the difference
in result is not to be wondered at. But this I feel satisfied is
by no means the whole of the cause of difference ; for if those
among us who are able to give but a few hours a week to
microscopic research (which has been almost constantly my
own case), would but apply those few hours to the prosecution
of some definite department of study, they would come to
feel, I am confident,.a far higher interest in their pursuit,
and would be in a far more favourable position to add some-
thing to the common stock of knowledge, than by expending
their time in desultory observations. And this will be espe-
cially the case, when the student, in the selection of his
department, consults his means and opportunities for invest1-
gating it, as well as his tastes, so as to protect himself as
much as possible from being cramped in his inquiries by
want of the necessary material. There is always, of course,
a danger that the inexperienced inquirer will not duly inter-
pret what he sees, and that he may draw wrong deductions
where he observes aright; but this danger is greatly dimi-
nished when he confines his attention within a narrow range,
instead of trying to comprehend the whole of the “ world of
small” within his survey; since he will find it much easier to
acquire that guiding knowledge which already forms part of
the fabric of physiological science, when the required amount
of that knowledge is limited, instead of being voluminous ;
and his corrective experience will be much more speedily
rendered precise and efficient, when it is constantly brought
to bear on the same class of facts, than when it is only occa-
sionally called into play through the too-wide range of his
observations. I should be far, however, from recommending
any one to limit himself entirely to a single department of
microscopic study; on the contrary, the highest education
of the eye, or rather, of the perceptive mind (for it is after all
the mind that sees, and not the eye), can only be attained by
a widely-extended course of observation. And every young
microscopist, in first training himself in the knowledge of
what to observe and how to observe, will do well to examine
objects of the most varied kinds, and to learn as much about
them as his time will permit. But it is when this preli-
minary education has been passed through, that I strongly
urge the limitation of the attention to particular departments

Address of the PRESIDENT. 21

of research, as the means by which alone, in this, as in every
other branch of scientific inquiry, can any really ‘good results
be attained.

I hope that I shall not be supposed desirous of trumpeting
the merits of my own production, if I say that in the ‘ Manual
of the Microscope,’ which I have just brought to a conclusion,
I have especially aimed, on the one hand, to put the young
microscopist in possession of what it is most essential that he
should know at starting, on cach of the most important topics
to which his attention may be directed ; and on the other, to
point out how much remains to be known, and to guide him
into the path of research which he may follow with the great-
est likelihood of beneficial results. And I cannot point to a
better example of the advantage to be derived from the steady
devotion of the attention to a definite object, than is presented
by the admirable contributions which have been made during
the last year by Mr. Wenham, to two most important depart-
ments of vegetable physiology; especially by his memoir on
_ Vegetable Cell Development, which appears in the last part
of our Transactions (Jan. 1856). To this I shall presently have
occasion to make particular reference; and I shall now only
remark, that I look upon it as one of the most important
rectifications which the current doctrines of this science have
ever received ; and that, although the product of one who
must be considered an amateur rather than a professor of
science, it would, in my opinion, do credit to the most accom-
plished physiologist, ” I should have hesitated, perhaps, at
pinning my faith upon Mr, Wenham’s statements, had it not
been for two circumstances which have had a powerful influ-
ence with me: in the first place, the care in observing, and
accuracy in recording, of which Mr. Wenham’s previous
paper on the ‘ Rotation of Sap in Vegetable-cells’ gave satis-
factory evidence ; and secondly, the ehincidence of the results
of Mr. Wenham’s researches and conclusions, with those
towards which many recent inquiries on the history of cell-
development seem to me to converge.

It is of great importance to the progress of any department
of Science, that we should from time to time review the
state of our knowledge on those fundamental questions which
affect its condition and aspect; and it appears to me that the
time is now come, when we must take such a review of the
Cell-theory of Schleiden and Schwann, in its relation to
Vegetable and Animal Physiology. To such # review I pro-
pose now to lead you: it must necessarily, from the briefness
of the space at our command, be a very cursory one; but I
venture to hope that I may Seecnd in so placing before you

22 Address of the PRESIDENT.

the aspect under which the questions at issue present them-
selves to my own mind, as to lead you to a conception of
the mode in which (as it appears to me) their solution is to
be sought for. That I have myself fully attained that solution
I dare not affirm. That the principle I offer to you, however,
is more consistent with known facts, than are the doctrines
commonly entertained, I feel a very strong conviction,

Although the general organization of Plants was so far
understood at the time when Schleiden first came before the
public, that every vegetable tissue was recognised as essen-
tially cellular in its nature, yet I consider it to have been by
him that the fundamental truth was first broadly enunciated,
in 1837, that, as there are many among the lowest orders of
plants in which a single cell constitutes the entire individual,
each living for and by itself alone, so each of the cells, by the
aggregation of which any individual among the higher plants
is formed, has an independent life of its own, besides the
‘incidental’ life which it possesses as a part of the organism
at large; and that the doctrine was first proclaimed, that the
life-history of the individual cell is, therefore, the very first
and absolutely-indispensable basis, not only for Vegetable
Physiology, but (as was even then foreseen by his far reach-
ing mental vision) for the science of life in general. The
first problem which he set himself to investigate, therefore,
was, how does the cell itself originate? It is unfortunate that
he should have had recourse for its solution to some of those
cases in which the investigation is attended with peculiar
difficulty ; and it is, doubtless, in great part to this cause, that
we are to attribute certain fallacies in his results, of which
subsequent researches have furnished the correction.

The publication of the ‘ Microscopical Researches’ of
Schwann, in 1839, marks a like era in Animal Physiology.
For although the doctrine could not be said to be a new one,
that each integral part of the animal body possesses an inde-
pendent life of its own, in virtue of which it performs a
series of actions peculiar to itself, provided that the condi-
tions of these actions be supplied, yet it derived a new
significance from the idea with which he connected it, that
the integral parts are either cells or derivatives from cells, and
that their independent life is, therefore, cell-life. ‘This idea,
avowedly suggested by that of Schleiden, was based by
Schwann on the apparently-satisfactory results of his micro-
scopic observations on the development of the animal tissues.
For he found, that however diverse may be the structure and
actions of the component parts of the animal organism in
their fully-developed condition, there is a period in its

Address of the PRESIDENT. 23

history when it is nothing else than an aggregation of cells,
all apparently similar to each other; and as in some of the
tissues—for example, in the blood-corpuscles, fat, cartilage,
epidermis, epithelium, and the grey matter of the nervous
centres—the cellular character is preserved throughout life,
so might it be reasonably inferred that the rest are derived
from cells, by a metamorphic process whose consecutive
stages might be traced by microscopic observation. This
was the problem which Schwann set himself to elucidate, and
which he has been generally considered to have gone far to
solve. For although an exception was early taken by
various observers both on the continent and in this country,
in regard to that simple fibrous tissue which is formed by the
fibrillation of the effused blastema or organizable plasma of
the blood, almost every microscopic observer, down to a very
recent period, who has devoted himself to this department of
inquiry, has taken Schwann’s idea as his guide, and has con-
sidered it to be his main object to extend and complete it,
by more fully elucidating the series of steps by which bone,
tooth, shell, muscle, nerve, &c., are evolved from the cells in
whick they have have been almost unquestioningly believed
to originate.

The doctrine of Schwann and his followers, however, has
lately been the subject of very acute criticism on the part of
Mr. Huxley; who has urged many arguments for the conclu-
sion, that the cell is not the essential integer of the living
organism which it has been, and still is, held to be by most
physiologists ; that it is only one out of many forms of organic
structure, into which the organizable blastema may evolve
itself; and that many animal tissues may form themselves
directly out of this blastema, without undergoing the inter-
mediate condition of cells.*

Although I am not by any means disposed to go as far as
Mr. Huxley in abandoning the cell-doctrine of Schwann and
his followers, yet I cannot but admit the correctness of much
that he has urged. ‘The essential truth, however, seems to
me to lie between the two extremes; in other words, the cell-
doctrine of Schwann can only be accepted when the word
“cell” is understood in a sense much wider than that to
which he limited it; but when it has been thus modified,
there does not seem to me to be any adequate reason for
relinquishing it. Fresh light having been thrown upon the
subject by recent researches into the lowest types both of

* See his Memoir on the Cell-Doctrine, in the ‘ Brit. and For. Med.-
Chir.” Rev.,’ vol. xii.; and his article, ‘ Tegumentary Organs,’ in the
‘ Cyclop. of Anat. and Physiol.,’ supplementary volume.

24 Address of the PRESIDENT.

vegetable and animal life, I shall first proceed to inquire how
far these researches tend to modify our idea of what consti-
‘tutes a cell; and shall then test these modifications by the
results of inquiries into the structure and development of
more complex organisms.

The typical vegetable cell has commonly been considered
to consist, externally, of the cellulose wall,—next to this, of
the primordial utricle,—within this, of a iver of protoplasm,
usually mingled with chlorophyll-granules,— and, finally, of
the liquid cell-contents. But we find, among the simplest
Protophytes, that all the functions of vegetative life are per-
formed by beings which do not present any such differentia-
tion of parts. Thus each individual of the Palmoglea
macrococca (Kutzing) seems to be a particle of viscid plasma
containing green granules, having neither definite limitary
membrane on its surface, nor definite cavity in its interior ;
and this is surrounded by an indefinite gelatinous envelope,
which usually coalesces with that of other similar particles,
so as to form a continuous slimy matrix. Now each of these
particles has a nucleus like that of fully-developed cells; it
increases by drawing into itself nutritive materials, which it
converts into the organic compounds it requires for its aug-
mentation; it undergoes duplicative subdivision, by which
the single particle gives origin successively to two, four, eight,
&c., after the ordinary method of multiplication of unicellular
plants; and finally it conjugates with another like itself, the
substance of the two particles being fused together in such a
manner as to demonstrate the non-intervention of any limitary
membrane, and the product being a “‘ spore” or rather a “ pri-
mordial cell,” which originates a new generation by the re-
newal of the process of duplicative subdivision.

Now if we compare the life-history of this Palmoglea with
that of any unicellular plant that may be familiar to us,—-one
of the Desmidiacee for example,—we shall see that in all
essential particulars it is the same; and that the only differ-
ence lies in the less-developed condition of the former as com-
pared with the latter. For if its nearly homogeneous mass of
protoplasm were to take upon itself that tendency to differ-
entiation of its component parts, which operates in the pro-
duction of the perfectly-developed vegetable cell, a very easy
transition would speedily manifest itself from one condition
to the other. For the surface of the protoplasm would gradu-
ally undergo condensation, so as at last to be converted into a
more or less definite Deere: the “ primordial utricle ;” *

* It is maintained by some recent observers, that the “ primordial
utricle” of Mohl is not to be regarded as a proper membrane, because it 1s

Address of the PRESIDENT. 25

at the same time, ‘“‘ vacuoles” filled with a more liquid mate-
rial would appear in the substance of the protoplasm, and
these would increase and coalesce, until at last the principal’
part of the interior would be occupied by the watery fluid,
the viscid protoplasm being confined to the layer immediately
lining the primordial utricle. Further, the secretion from
the surface, instead of being a soft gelatinous slime, would
constitute a firm protective envelope,—the cellulose wall.
Now this is what may be actually seen, in following the evo-
lution of the “ zoospores” of Conferve, &c., into perfect cells ;
for these zoospores are nothing else than protoplasmic parti-
cles, formed by the subdivision of the contents of the cell
from which they are set free, having one or more filamentary
prolongations, by the vibration of which they are propelled
through the water; and it is not until they have fixed them-
selves, and have begun to grow, that they present any indica-
tion of that_ distinction of parts, which I have spoken of as
characterizing the typical cell.

There is another phase in the lives, not only of Protophytes,
but of more highly-organized plants, in which, according to
recent observations, a most important functional act is per-
formed by particles of protoplasm not yet furnished with a
cell-wall. Thus in Vaucheria, in which the existence of dis-
tinct sexes, and the performance of a true generative act has
been substantiated by the admirable observations of Prings-
heim, it seems very clear that while the contents of the sperm-
cell are metamorphosed into self-moving antherozoids which
make their escape from it, those of the germ-cell simply form
an aggregate spherical mass in its interior, which, at the time
of the entrance of the antherozoids, has no limitary membrane.
The antherozoids, coming into contact with its surface, swarm
over it, and seem to undergo dissolution upon it ; and it is not
until a fusion has thus been accomplished between the con-
tents of the sperm-cell and those of the germ-cell, that the
product of this fusion becomes invested with a definite mem-
brane, and is thus developed into acell. The observations of
Dr. F. Cohn upon the generation of Spheroplea annulina are
to precisely the same effect ; and Dr. Pringsheim, carrying out
more fully the observations of Thuret on the fertilization of

simply the superficial layer of the protoplasm more condensed than that
which it encloses. It does not appear to the Author that this constitutes
a sufficient reason for recognizing it as a definite membrane, where it has
a membranous consistence. And the controversy will be seen to be one
of words rather than of things, when the presence or the absence of this
membrane is viewed as a matter simply depending upon the degree of
differentiation which the protoplasm may have undergone.

26 Address of the PRESIDENT.

the Fuci, has ascertained that the same holds good in their
case, ;

Thus, then, we are driven either to admit that the essential
integers of the vegetable organism,—that which may not only
maintain an independent existence, but may increase and mul-
tiply both by self-division and a true generative process,—is
not (as we have hitherto supposed it to be) a cell; or we are
constrained to modify our definition of a cell, so as to make it
include bodies which do not possess the attributes that have
been hitherto involved in this designation. Whichever we do,
we should keep constantly in mind the relationship of the two
objects. For the nucleated particle of protoplasm, although
not structurally a cell, is a cell physiologically, possessing all
its most important functional endowments; and although it
may never develop itself into the type of a cell in a few of
the lowest Protophytes, which pass the whole of their lives in
this homogeneous condition, yet in by far the greater number
this simpler state is but transitory, the homogeneous particle
of protoplasm speedily differentiating itself into a true cell ;
so that although not a cell actually, it may be regarded as
a cell potentially. Instead, therefore, of characterizing the
simplest type of vegetable organisation as a cell, having a
distinct membranous envelope and liquid contents, we should
more correctly describe it as a nucleated particle of protoplasm,
that may either remain in that low grade of incipient organi-
sation of which a homogeneousness (approximating that of in-
organic bodies) is the distinctive feature, or may make that
first advance in organisation which consists in the differentiation
of its substance into the more solid envelope and the more
liquid interior, the cell-wall and the cell-contents.

Now it is in showing that a process essentially the same takes
place in the first formation of new organs in the higher plants,
that the great value and interest of Mr. Wenham’s paper con-
sist. It has usually been supposed that every leaf originates
in the duplicative subdivision of a certain cell of the axis, and
that its subsequent extension is due to the continuance of the
like process of cell-multiplication. Mr. Wenham has shown,
on the contrary, that (an certain cases, to say the least) the
leaf originates in a layer of protoplasm, which is in the first
instance homogeneous, but in which large vacuoles, disposed
with a certain degree of regularity, soon make their appear-
ance ; these vacuoles become the cavities of the first cells,
whilst the plasma between them, acquiring increased consist-
ence, become the walls of these cells. Sometimes, when one
of the first-formed vacuoles is unusually large, it is divided
into two by the extension of a bridge of protoplasm across it ;

>

Address of the Present. 27

on the other hand, if the plasmatic division between the
vacuoles should be unusually broad, a new vacuole forms in
its substance. Now this mode of cell-development I believe
to be altogether a new fact to physiologists; and although Mr.
Wenham’s observation stands as yet unconfirmed, yet it
accords so well, on the one hand, with the facts which I have
stated with regard to the simpler Protophytes, and on the
other, with appearances which I have myself observed in
various animal structures, that I feel a strong couviction of its
essential truth.

If, now, we direct our attention to the Protozoa, or simplest
forms of animal life, with a view to inquire whether there be
among them any phenomena of a parallel kind, we are at once
struck with the strong resemblance which their condition bears
to that of the humblest Protophytes. Taking the well-known
Actinophrys sol as a typical example, we find that it consists
of a nucleated particle of “ sarcode” (the equivalent of the
vegetable “ protoplasm”), whose destitution of anything like
limitary membrane is evidenced by its extraordinary power
of extending itself into filaments, which, when they happen to
meet each other, undergo a complete coalescence. Yet this
nucleated particle behaves, in many respects, as a true cell.
It draws nutrient material into its interior, applies it to the
augmentation of its own substance, and multiplies itself by
duplicative subdivision. It has been supposed even to per-
form the generative act by conjugation with other particles
like itself; but recent observations upon Actinophrys and
allied organisms, have rendered it very doubtful whether
the fusion of two of these particles is a real conjugation ;
since no special product has been observed to result from
it; and not only two, but several, individuals have been seen
thus to coalesce together, the composite mass afterwards
resolving itself again into isolated particles not apparently
differing in any respect from the originals. What is the true
meaning of this act, therefore, we are at present unable to
affirm ; but the fact, however we may interpret it, is in itself
extremely significant, as affording an additional proof of the
homogeneousness of the sarcode-body of the Actinophrys.
I need scarcely stop to remark, that the same is true of the
animal bodies of the Foraminifera generally ; for these, in so
far as we are acquainted with them, are nothing else than
homogeneous particles of sarcode, extending themselves into
pseudopodia, whose coalescence, when they happen to encoun-
ter one another, affords ample evidence of the non-existence
of any limitary membrane. In Ameoba, the distinction between
cell-wall and cell-contents begins. to show itself; the super-

*

28 Address of the PRESIDENT.

ficial portion of the sarcode having decidedly more consistence
than the interior ; and the pseudopodia being much less freely
extended. Still, however, the consistence of this external
layer is not such as to present any obstacle to the reception
of alimentary particles into the interior of the sarcode-body
through any portion of its surface, or to interfere with the
rejection of indigestible particles,—the temporary orifice, in
either case, being at once closed by the coalescence of its
edges ; so that there is obviously no definite limitary mem-
brane, notwithstanding that the liquidity of a large part of the
interior substance allows a free movement of granular particles
in every direction, as I observed many years ago. Thus, the
Ameba seems to me to represent that condition of the vege-
table cell, in which the primordial utricle is distinguishable
as the external more condensed layer of the protoplasmic
mass, but does not possess the distinctness of a proper mem-
brane. A more advanced stage is seen in the curious Gre-
garina, which must be regarded as corresponding with the
Protozoa in the simplicity of its organization, whilst it resem-
bles the Entozoa in the peculiarity of its habitat. For here,
the distinction between the cell-wall and the cell-contents is
decidedly marked ; the former becoming more consistent, and
the latter more liquid. The body undergoes great changes
of form, but no pseudopodial extensions are sent forth; and
the nutrient materials being imbibed in a liquid state by the
whole surface, neither are solid particles introduced by an
oral orifice extemporised in the superficial layer, nor are
rejectamenta extruded through a like extemporised anus.
Passing-on to the Infusoria, we find much reason to regard
these simpler forms (at any rate) in the light of cells modified
for an independent existence; and their essential difference
from Actinophrys and Amoeba seems to lie in this, that the
external layer of the sarcode is condensed into a more definite
limitary membrane,—a change which involves other altera-
tions. For, in the first place, the body can undergo compara-
tively little change of form ; and no pseudopodia can be sent
forth. And, secondly, as the alimentary particles can no
longer be introduced through any point of the surface, a
definite orifice is left in the membranous envelope, into
which the nutrient materials are driven by the peculiar dis-
position of the cilia; and, in many cases, a definite anal
orifice is also provided, through which indigestible matters
may be ejected. :

Thus, among the Protozoa, as among the Protophyta, whilst
we trace a gradual advance in the differentiation of the homo-
geneous particle of sarcode into the true cell, we find vast

Address of the PRESIDENT. 29

multitudes of beings passing their whole lives (so far, at least,
as we are acquainted with them) in that earlier and simpler
condition, in which no such differentiation has taken place,
and in which, therefore, the structural constitution of a cell
has not been attained.

Now before I pass on to inquire how far this condition
finds its parallel in the elementary parts of higher organisms,
I wish to stop for a moment, to notice how strongly the
differences between the Vegetable and Animal kingdoms are
marked out, even in those lowest and simplest forms of both,
which we have been just engaged in considering. For the
Protophytes, like the most perfect Plants, draw their nutri-
ment from the inorganic compounds which are everywhere
within their reach,—water, carbonic acid, and ammonia; by
decomposing carbonic acid, they give off oxygen; and they
form for themselves the starch and the chlorophyll, the cellu-
lose and the albumen, which they apply to the augmentation
of their own substance. On the other hand, even those hum-
blest Protozoa, the Rhizopoda, can only exist (so far as we
can see) upon organic materials previously elaborated by
other beings: these they receive ‘‘ bodily” into their interior ;
and though mouth, stomach, intestine, and anus, all have to
be extemporized every time that the animal feeds, yet the
digestion which the alimentary particles undergo in its
interior, is not less complete than that which is performed by
the most elaborate apparatus which we anywhere meet with ;
and the nutrient materials thus obtained seem to be appro-
priated, without any further conversion, to the augmentation
of the substance of the body. Thus, notwithstanding the
remarkable analogy which these two orders of beings exuilpia
I cannot see that any difficulty need be experienced in
separating them, when we are acquainted with their mode of
nutrition. The Gregarina constitutes no real exception; for
although it imbibes its nutriment through its entire surface,
like the Protophyte, yet that nutriment has been previously
digested and prepared for it by the animal whose body it
inhabits ; and in the absence of any oral orifice or digestive
apparatus of its own, it corresponds with a far higher group
of animals, the Cestoid Worms, which live under the same
conditions. Some recent observations, it is true, would seem
to invalidate this distinction, by showing that certain rhizopods
and infusoria have their origin in undoubted plants ; but we
must be permitted for the present to withhold our assent from
conclusions so strange, and to question whether they may not
be invalidated by some unsuspected fallacy. It has been well
remarked, however, that ‘ there is no limit to the possibilities

VOL. IV. d

30) Address of the PRESIDENT.

of Nature ;” and | should be the last to attempt to set up as
fixed laws what are merely the expressions of the present state
of our knowledge, or to wish to throw discredit on the ob-
servations of accomplished and careful microscopists, merely
because they overthrow distinctions which I had imagined to
be well founded. I would strongly recommend the observa-
tions of Professor Hartig (Quart. Journ. of Microsc. Science,
Vol. IV., p. 51) and of Mr. Carter (Ann. of Nat. Hist., Feb.,
1856) to your attentive scrutiny; and hope that some of our
members may be able, ere long, to furnish either a confirmation
or a refutation of them.

Turning, now, to some of those parts of the fabric of higher
animals, in which a cellular organization has been described
by some observers and denied by others, I think I shall be
able to show that the discrepancy is capable of being recon- —
ciled, by the application of the principle of progressive dif-
ferentiation to the mass of sarcode in which any such organ
originates. Thus having found, in various kinds of shells,
certain instances in which a very definite cellular organization
appeared to me to exist,—others in which this organization
was less definite, though still (as I thought) unmistakeably
present,—others in which it was only faintly indicated,—and
others in which I could discern no traces of it ;—and having
also met with gradations from one condition to another, even
in the very same shells ;—I thought myself justified in con-
cluding that the animal basis of the shell-substance must have
been originally cellular in every case, but that the divisions
between the cells must have been lost in some cases by a very
early coalescence. Mr. Huxley, on the other hand, has recently
expressed an opinion,* founded on an examination of my own
preparations, that the whole of my interpretation is erroneous,
and that no cellular structure can really be discerned in shell.
Now in the justice of this verdict, | cannot say that I am pre-
pared to coincide ; on the other hand, I am quite ready to
admit that my original interpretation requires modification.
Taking the general history of the first formation of a leaf from
a layer ‘of protoplasm, as probably applicable to the formation
of a lamina of shell from a layer of sarcode, I should now
interpret the appearances which my preparations exhibit, as
follows :—In those forms of shell-substance in which I can
discern no structure whatever, and in which a continuous
membrane is left after decalcification, I should be disposed to
think that the entire layer of sarcode has undergone calcifica-
tion, before any differentiation of parts had begun to take place
in it. In those again in which (as in Mya and Thracia) a

* ‘Cyclopedia of Anat. and Physiol.,’ Supplement, p. 489.

Address of the PRESIDENT. dl

cellular arrangement is more or less obvious in the section,
but in which no distinctly-cellular residuum is left after decal-
cification, I should infer that the processes of vacuolation and
of consolidation had commenced, but had not proceeded far,
when the calcification took place. Lastly, in those in which
(as in Pinna) a very definite residuum, apparently cellular, is
left after decalcification, the very striking resemblance which
this bears to that stage in the vacuolation and consolidation of
a layer of protoplasm about to form a leaf (as described and
figured by Mr. Wenham) which immediately precedes the
formation of distinct cells, induces me to think that such must
have been the stage in which the sarcode-layer must have
undergone calcification. Hence, whilst agreeing with Mr.
Huxley that in few (or perhaps none) of the structures which
I have described as cellular, are any complete cells ordi-
narily formed, [| still believe that in all of them there has been
a nisus more or less operative, towards the development of
cells; their differences lying solely in the greater or less
degree of differentiation, tending towards the production of
perfected cells, which had manifested itself in the sarcode at
the time of its calcification.

I am strongly disposed to believe, that the same doctrine
will apply to many other animal structures, in which the pre-
sence of a cellular organization is affirmed by some and denied
by others. If, for example, you look at the scale of an Eel,
you observe that its otherwise homogeneous substance is marked
out by ovoidal spaces, which suggest the idea of cartilage-cells
with an intervening matrix. By Professor Williamson, who
_ has carefully studied the structure of fish-scales,a layer of this
kind has been shown to be of very general occurrence ; and
he considers these ovoidal spaces to be “ botryoidal concre-
tions” of calcareous matter, having no relation whatever to
cells. And he puts the like interpretation on analogous
appearances exhibited by various egg-shells, which have been
regarded by Professor Quekett and others as indicative of a
cellular organization. Now the microscopic appearance of
the scale of the Eel so precisely resembles that of the leaf-
forming layer of protoplasm, as figured by Mr. Wenham, that
I can scarcely doubt that its ovoidal spaces are vacuoles
formed with a view (as it were) of becoming cells; and that
the regularity of the shape and disposition of the calcareous
concretions is determined by that of the vacuolations. And
the condition of such egg-shells as exhibit an appearance of
cellular structure, so closely resembles that of many shells of
mollusks, in which there is a cellular areolation without well-

32 Address of the PRESIDENT.

defined membranous partitions, that 1 can scarcely hesitate in
attributing to it a similar origin.

The general doctrine, then, which seems to me best to
express the facts I have stated, is that those essential endow-
ments which we have been accustomed to attribute only to
the typical cell, may exist in that comparatively-homogeneous
substance which is commonly termed “ protoplasm”’ in the
vegetable kingdom, and “ sarcode” in the animal; that iso-
lated particles of this substance may comport themselves after
the manner of true cells, although no distinction between
cell-wall and cell-contents may have made itself apparent ;
and that various organs and tissues among the higher plants
and animals have their origin in larger extensions of the same
substance, in which the process of ced/ulation may either pro-
ceed to the complete evolution of an aggregate of perfect cells,
or may be stopped at any point, so as to leave but faint traces
of the tendency in question. I have already adverted to the
belief which I have from the first entertained, that in the
animal body, the fibrillation of the blastema may take place
quite independently of cellulation; and I am much disposed
to think that the formation of other tissues may take place
by alike direct process of conversion. But I wish to take
this opportunity of protesting against the assertion, that
where no perfected cells can be demonstrated, there is not a
tendency to a cellular organization, however incomplete may
be its result. It would be just as unphilosophical, in my
opinion, to assert that the white fibrous tissue does not mani-
fest the tendency of the blastema to fibrillate, because it
seldom exhibits isolated sharply-defined fibres like those of
the yellow or elastic tissue.

Some apology might, perhaps, seem due for thus occupy-
ing your time in an abstract physiological disquisition ; but
next to correct observation, is the right interpretation of what
we see; and, in fact, it is often extremely difficult (as is
obvious in the history of this very inquiry) to distinguish
between the impressions which the objects themselves make
upon our minds, and the ideas which we connect with those
impressions. And I am desirous that those whom I have
now the pleasure of addressing, should be put in the way of
examining for themselves into the merits (1) of the cell-
doctrine as commonly held, (2) of the opposite view put
forward by Mr. Huxley, and (3) of the intermediate doctrine
which I have this evening endeavoured to expound.

Address of the PRESIDENT. 33

It now only remains for me, in resigning the chair to m
successor, to thank you most gratefully for the kind indulg-
ence which you have so constantly extended to me; and to
express my regret that I have not been able to do more to
promote the interests of the Society, by myself furnishing
original communications to its meetings. It is known to
many of you, that the small amount of time which I can
spare for original research, has long been devoted to one
special object, the elucidation of the structure and physiology
of the Foraminifera; and the liberal assistance which has
been afforded me by the Royal Society in the prosecution of
my researches (whereby I have been enabled to procure the
unrivalled series of microscopic drawings that I have exhi-
bited from time to time at our meetings), makes me feel it
but common gratitude, to place before that Society the
systematic results of my researches. And further, the
number and variety of demands upon my time have entirely
precluded my making any such active exertions to obtain
communications from others, as may not unreasonably be ex-
pected from your President. I have the gratification of
believing that my successor may be much more able than I
have been, to contribute to your welfare in both these modes;
and it is, therefore, with much satisfaction that I look for-
ward to being replaced by one of the oldest members of the
Society, who has given evidence of such extensive attainments
in various departments of Microscopical Science, and who
will, I feel confident, do the fullest credit to your choice. I
have only to beg you to believe, that the warmest desire to
promote the interests of the Society has never been wanting
on my part, and that nothing but the coercion of circum-
stances, which I could not control or resist, has prevented me
from more fully manifesting the sincerity of that desire in
labour for your benefit.

x

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a ede

On the Post-rertiary Diatomaceous Sanp of GLENSHIRA.
Part IT. Containing an account of a number of additional
undescribed species. By Witi1amM Grecory, M.D.,F.R.S.E.,
M.R.I.A., &c.; Professor of Chemistry in the University
of Edinburgh. Illustrated by numerous figures drawn from
Nature, by R. K. Greviiiz, LL.D., F.R.S.E., &c., and
engraved by Turren West, Esq. (Plate V.)

(Read March 26, 1856.)

In the first part of this communication * [ described the pecu-
liar locality in which the Glenshira Sand occurs, and pointed
out, that the remarkable mixture of marine and fresh water
forms which it contains, was a proof that, when this sand or
mud was deposited, the fresh-water lake, then filling the
upper part of the valley, and standing, of course, at a higher
level than it now does, must yet have occupied the same
relative level, compared with the sea, which it now occupies,
when it is confined to the lowest part of the valley, and being
exactly at the level of half-tide, flows into the sea at low
water ; while, at high water, the sea flows into the lake. This
state of matter produces in the lake, at this moment, a mix-
ture of marine and fresh-water species, not only of diatoms,
but also of other tribes, both animal and vegetable. And as
the. existence of a similar mixture in the sand now under ex-
amination, deposited at the higher level, implies that at the
period of its deposition the relative levels of the sea and of
the lake were the same as now, while we see that the lake
now stands at a lower level than formerly, we infer, that since
that period the land has risen, or the sea has fallen; a con-
clusion justified and supported by many other geological phe-
nomena in the estuary of the Clyde, with which Loch Fine,
the arm of the sea into which the Dhu Loch of Glenshira
flows, communicates.

In the same paper I gave a list of about 215 known species
of Diatoms, and nearly 20 undescribed species, which I had
found in the deposit ; a number of species far exceeding that
hitherto found in any other similar deposit, so far as is known
to me. This, I conceive, indicates that the circumstances
which favoured the mixture and accumulation of species must
have been of very prolonged duration.

At the same time I stated that there remained about as
many more undescribed forms as those I had been able at that
time to figure, and that these should be figured and described
on some later occasion. I now proceed to fulfil that promise.
I must explain, however, that it is impossible for me to com-

* ¢ Quarterly Journal of Microscopical Science,’ vol. iii., p. 30.
VOL. IV. é

-

36 Dr. Greeory, on the Post-tertiary

plete the investigation in the present paper. In the first
place, the sand is not yet exhausted ; for although I have ex-
plored about 600 slides of it, new forniis are sf toes tae to
time occurring. Secondly, it has been found impossible to
finish the study even of the whole of those which I had ob-
served in it in 1854, and to prepare figures of them. I pro-
pose, therefore, only to describe and figure, at this time, such
of the new forms as have been duly studied. This is, no
doubt, the majority of them ; but it will require a third paper
to complete the examination, more especially of the smaller
forms, among which, as well as among those of the larger
which have not yet occurred entire, much remains to be done.

Before describing the new forms, I must add to the list of
known species formerly given the following, many of which
were accidentally omitted. Others have since occurred to me,
and a few have been pointed out to me by Mr. Okeden, well
known as a zealous observer. These I have also myself seen.

Additional List of known Species.

235.* Cymbella sinuata, W. G, 250. Navicula Pandura, Bréb. (?)
236. Amphora membranacea. 251. Pinnularia megaloptera, Ehr.
237. a salina. 252. ‘4 biceps, W. G.

288. : hyalina. 20. ~, linearis, W. G. .
239. Amphiprora paludosa. 254, #3 subcapitata, W. G.
240. Campylodiscus Ralfsii. 255. »» + sracillina, WW. .
241. Actinocyclus undulatus. 256. Pleurosigma distortum.

242. Actinocyclus ? ate u, intermedium.
243, Actinocyclus duodenarius, Sm. | 258. Gomphonema subtile, Ehr.
244. Nitzschia bilobata. 259. Orthosira spinosa.

245. Navicula Westii. 260. ae mirabilis.

246. ns obtusa. 261. Grammatophora Balfouriana.t+
247. 55 Hennedii. (See Synopsis, Vol. II. Pl. LXI.
248. 2s rostrata. fig. 383.)

249. Navicula varians, W. G. (in
all its forms).

On this list I would only remark, that the species marked
W.G. have been lately described by me, as well as Nos.
248, 251, and 258, the two last as new to Britain;} that No.
249, Navicula varians, has been also fully desoneen by me
elsewhere : § that No. 243, Actinocyclus duodenarius, appears

-* These numbers are continued from Part I., in which J gave a list of
234 species.

+ Ihave given a figure of this form, as being little known as yet. At
first it seemed to differ from the form ‘ficured by Dr. Greville, the inter-
rupted vittz being less conspicuous, the striee more so ; : but I am now
satisfied that it is essentially the same form, which varies, however, more
than was at first supposed. The figure is not numbered, as it is not
intended for engraving.

+ ‘ Quarterly Journal of Microscopical Science,’ vol. iv., p. 1.

§ ‘Trans. Micr. Soc., Quart. Journ. of Micr, Science,’ No. X., p. 10,

Jan. Loop.

a

Diatomaceous Sand of Glenshira. 37

as a British form in Vol. II. of Smith’s Synopsis. I have
found in Glenshira several forms of this kind, differing only
in the number of septa, which varies from 7 or 8 to 14 or
16. I observe in Pritchard’s Animalcules, that Ehrenberg
makes a species of each number of septa ; but to judge by the
aspect of these forms in Glenshira, they are all of one species,
which I have named duodenarius, because 12 is about the
average of the septa in those I have seen there. No. 250,
Navicula Pandura, was last year figured by De Brébisson as
occurring at Cherbourg. I mark it with a query, because it is
doubtful whether it may not be the same species as WV. nitida,
Sm., (named in my former list,) and also because I have
great doubts as to either of these forms being correctly named.
They belong to a very striking group, in which the Glenshira
sand is somewhat rich, and which I shall have presently to
consider more fully.

Of No. 247, Navicula Hennedii, I give a figure, because very
fine specimens occur in this deposit, and the form has not yet
been figured, though it will be described in Vol. II. of Pro-
fessor Smith’s Synopsis. The two Orthosir@ are also new
forms; O. spinosa having been found in Braemar by Drs.
Greville and Balfour, and in Auvergne by Professor Smith,
and figured both by Dr. Greville and Professor Smith ; and
O. mirabilis having been found last summer in Wales by Mr.
Okeden, but not yet figured. I may here mention, that I had
observed and sketched both, in my earliest explorations of the
Glenshira sand, fully three years ago; but from the number
of new forms, T was compelled to postpone the study of them,
and had not been able to resume it when the naturalists above
named discovered them. But before the account of O. spinosa
had appeared, I had again found both forms in three or four
South American soils. I mention this here, because my ob-
servations on these soils have led me to doubt whether O.
mirabilis be not an abnormal state of O. spinosa.

My reasons for thinking so are: 1. That inall the localities
in which O. mirabilis occurs, it is accompanied by O. spinosa.
2. In the Glenshira sand and in the American soils, I was un-
able to find any discoid or end view, or diaphragm, which I
could suppose to be that of O. mirabilis, except that of O.
spinosa; and I believe that Mr. Okeden has been equally
unsuccessful. 3. I found one cylinder, one-half of which had
the peculiar markings of O. mirabilis, narnely, two series of
curved or sigmoid lines, decussating and crossing the cylinder
transversely ; while the other half had all the characters of
O. spinosa. 4. In no specimen of O. mirabilis have I seen
any appearance of the usual septa, so strongly marked in

e 2

38 Dr. Grecory, on the Post-tertiary

O. spinosa, which leads me to suppose that the markings are
due to the septa having been removed and replaced by some
new internal arrangement. 9. In both forms, the ends of the
cylinders exhibit the spines, or appearance of spines, from
which OQ. spinosa is named. It was for these reasons that I
did not earlier mention O. mirabilis as a species; and as for
O. spinosa, I had postponed it with other forms, otherwise
both might long ago have been known.

Let us now turn to the new forms. Here I must premise
that a few of those new figures were described and figured in
my former paper. I have figured these again, in some cases, be-
cause the former figures were accidentally erroneous ; or in
others, on account of additional peculiarities, or because I
now understand the forms better than I was at that time able
to do. By far the greater part of the forms now given are
figured for the first time.

1. Navicula rhombica, n. sp. In my former paper are
two figures of this species, which is very frequent in the
sand. I now give two more figures, to complete the history
of it.

Length from 0-001” to 0-0025”. Form rhombic, with
somewhat acute apices as in the former figures, or elliptic
lanceolate, with obtuse extremities, as in fig. 1. Stria fine,
but easily seen with a good 1-4 or 1-5, about 45 in -O0O1”, but
those near the middle of the valve much more distant, so as
to be almost conspicuous ; the striz slightly inclined. Median
line strong ; nodule large and well marked. Valve colourless,
or pale yellow.

The above characters sufficiently distinguish this species
from WN. rhomboides, which, in the typical form, is always
acutely rhombic, of a much darker colour, and has no definite
central nodule, the two halves of the median line ending in
sharp triangular points. The striz in WV. rhomboides are so
fine, that I have never yet been able to see them with a 1-5
of extraordinary goodness, and they are indeed hardly to be
resolved by the 1-8; they are also parallel. All these things
unite to give to WV. rhombica an aspect so entirely different
from that of WV. rhomboides, that it is impossible to confound
the two forms, where, as in the present deposit, they occur
together. I may add that the variations of NV. rhomboides,
viz., WV. crassinervia and WN. interrupta, W. G., are quite distinct
from those of NW. rhombica. I state this, because some who
have only seen the figures of NV. rhombica in my former paper,
have supposed that it is only WV. rhomboides. Those who have
seen the forms will admit that it is not possible for two species
of the same genus to differ more thoroughly; but it is im-

Diatomaceous Sand of Glenshira. 39

possible, in all cases, to represent in drawing, characters
which, in the forms, are perfectly satisfactory.

Since writing the former paper, however, I have observed
an additional mark of distinction, which has even led me to
doubt whether the form under consideration be a Navicula at
all; for it frequently occurs in what I may call packs, like
packs of cards, in which six, eight, or more are laid flat and
close on each other, I have represented one of these in fig. 1.*
This is a character which | have not observed in any Navicula,
although it is easy to imagine that some species of the genus
may occur in such groups. From the fact of these packs
being so frequent in a deposit like this, so long water-tossed,
it may be inferred, that the forms composing them are very
firmly attached together in the living state. I must leave to
better authorities to decide whether this be a Mavicula or not,
merely observing that it is a well-marked and beautiful species.

I believe WV. rhombica to be a marine form, having seen it,
with other marine species, in a recent gathering from the
coast near Tantallan, Haddingtonshire. ‘There were also
some fresh-water, or rather brackish-water forms, derived
from the mouth of a small brook near the spot. If it be
marine, this will be another point of distinction between it
and WV. rhomboides. I have seen no trace of it in all the very
numerous fresh-water gatherings I have studied, though
NN. rhomboides is one of the commonest forms (222.)f

2. Navicula maxima, n. sp. This was also figured in my
former paper, but I now give some additional figures of it,
both because I have since found much finer specimens, and
in order to show its usual varieties.

Form linear, broad, usually a little incurved at the middle,
with broadly acuminate apices, as in fig. 2. Also linear,
narrow and long, without constriction, as in fig. 2*. Some of
this variety are very long and narrow; and there are also
forms intermediate between 2 and 2*, as in fig. 2**. Length
from 0:0035” to 0°:0065”. Median line strong, usually some-
what bent towards the central nodule, at least in the broader
variety. Striz transverse, parallel, reaching the median line ;
fine and close, about 50 in 0:O0OL” in the broader, consider-
ably finer in the narrower variety. Colour of the valve in
balsam, clear straw yellow. The valve is thick and convex,
so that, when not lying quite flat, the edges become black.
It is a very striking form, and frequent in the coarser densities
of the prepared sand.

From the figure formerly given, some have supposed it to
be identical with MW. firma Bf, Sm. As that form was not

+ This is the number attached to the species in the list given in Part I.

AO Dr. Grecory, on the Post-tertiary

figured in the Synopsis, Vol. I., and I was at the time little
acquainted with it, | was at first inclined to adopt this view.
But a further examination of both forms has satisfied me
that they are distinct. WV. firma f has, even in balsam, a
strong brown colour; its striation is coarser, and far more
conspicuous, and is also slightly inclined; and it forms
several well-marked varieties, which have been: described and
figured by Ehrenberg as distinct species, such as JV. dilatata,
NN. amphigomphus, and others. Now, so far as I can see,
N. maxima exhibits no other varieties than those here figured,
which I give for the purpose of comparison. Moreover, while in
N. firma, in all its forms, we have a side line on each side of
the median line, WV. maxima bas usually two such lines on
each side. Lastly, both forms occur in this deposit, and are
easily distinguished by their general aspect, even under a low
power. (225.)*

3. Navicula Hennedit, Sm. I give a figure of this beautiful
species, because no figure of it has yet “been published, and
because the finest specimens [ have seen occur in the Glen-
shira sand. As it will be fully described in the Synopsis,
Vol. IL, I need only say here, that fig. 3 represents a very fine
one, although I have a specimen one-half larger even than
this, (247. st

4. Navicula latissima, n. sp. This is another very ee
species, which occurs very well developed in our deposit.

Form very broadly elliptical, with very obtusely acuminate
apices, having usually a very slight constriction before the
extremities. The sides are occasionally parallel in the middle.
Length from 0:002” to 0-005”, or even 0:006”. Some of the
shorter individuals, from the great breadth, are nearly or-
bicular. Nodule very large, median line doubly conical, the
bases of the cones meeting at the nodule. This appearance is
due to the striation, which does not reach the middle, and re-
cedes farthest from it near the central nodule. Striz rather
coarse, finely moniliform, bighly radiate, and not reaching the
true inner median line. Colour of the valve, in balsam, a
strong straw yellow, occasionally light brown. :

I understand that some are disposed to refer this form to
N. granulata, Bréb., which, as I stated in my former paper,
also occurs here. But I cannes do this; for in WV. granulata,
not only are the striz much less numerous, even though it is a
considerably smaller form, but they are composed of large
granules, so distant as to give a special character, from which
Be name is taken. In J. latissima, the striz# are indeed

* So numbered in Part I.
+ So numbered in the list of known forms, given at page 34.

Diatomaceous Sand of Gilenshira. 41

moniliform, as in many other navicule, but this character is
far from being conspicuous. Moreover, the invariable and
decided colour of the valve distinguishes it from NV. granulata,
which is colourless. Neither have I ever seen in UW. latissima
the produced or apiculate apices of NV. granulata. I consider
NN. latissima to have very well marked characters, and the
aspect of the larger individuals to be entirely peculiar.

Fig. 4 represents one of the shorter, and fig. 4* one of the
longer forms of this fine species. (262. )

5. Navicula quadrata, n. sp. (=. humerosa, Bréb. ) This
form is allied to the preceding, and is equally frequent in the
deposit.

Form rectangular or nearly square, the ends suddenly con-
tracted to short produced apices. Length from 0:0015” to
0-005” or even more, the breadth not increasing with the length
in the longer individuals. The usual length is about 0:0025”
or 0:003”. Striz radiate, much finer than in JW. latissima,
minutely moniliform, coming nearer to the median line. Fig. 5
represents an example rather below the average size.

When I first observed this form, and sent it to de Brébisson,
he told me that he had then just found it at Falaise, and had
named it NV. humerosa; but he preferred my name as having
been the earlier, and as more characteristic. Subsequently,
Professor Smith referred it to NV. granulata, Bréb., with which
it agrees in form, while it differs from it remarkably in
striation and aspect. De Brébisson, having found it quite un-
mixed with WV. granulata, still, I believe, regards it as a dis-
tinct species.* For this reason, | give it here as such, adding,
however, that I think it probable that it may prove to be a
variety, not indeed of WV. granulala, but of WN. latissima, from
which it differs, indeed, both in form and in number of stria,
but which it resembles considerably in general aspect. In my
paper on Navicula varians,} 1 have shown that neither outline
nor-number of striz are to be relied on, in certain cases, as
specific characters, and [ shall take an early opportunity of
directing attention to other tacts of the same kind which I
have since observed. I may add that in this deposit there
occur forms which, both as regards outline and striation, are
intermediate between this one and the preceding, WN. latissima.
_Even as a variety, however, it requires to be noticed and
figured, in order to give a correct idea of the species as we find
it. (263.)

I may here state that all the three forms, NV. latissima,

tor]

_.™ It appears as such, I find, in Vol. II. of the Synopsis, p. 98, as N.
humerosa. Of course I shall withdraw my name. and adopt that of de
Brébisson, to avoid confusion.

+ ‘Quart. Journ. of Mier. Science, No. X., p. 10, Jan. 1855.

42 Dr. Grecory, on the Post-tertiary

NN. quadrata, and N. granulata, are marine forms, and that
they all occur in recent gatherings on our coasts.

6. Navicula formosa, n. sp. This is a very beautiful form,
and is frequent in the coarser densities of the deposit.

Form, an elegant linear elliptic, or elliptic lanceolate, with
somewhat obtuse extremities. Nodules large and definite ;
median line like that of many Pinnularie, such as P. viridis.
Strie slightly inclined, about 35 in -001”, not reaching the
median line. There is, on each side of the median line, a
side line, parallel to it. Length from 0:003” to 0:0065.” ‘At
one time I referred N. maxima f and this form to one species,
but in WV. formosa the striae, besides being inclined, and not
reaching the median line, are much more conspicuous, giving
to the form a peculiar and well-marked aspect. I had also
some doubts, whether it should not be referred to Pinnularia,
rather than Wavicula, but I have preferred the latter, because I
believe the striz to be moniliform, though very minutely so.

Fig. 6 represents a specimen, nearly of the average size; it
is, however, often considerably longer. 1 have not yet seen it
elsewhere. (264.)

7. Navicula pulchra,n, sp. This very pretty form is not so
frequent in the deposit as most of the preceding species.

Form, elliptic lanceolate, almost rhombic, with a slight in-
flexion towards the extremities; not very broad. Length about
0-003.” Striz not very fine, very highly radiate, and very
strongly moniliform, which gives to it a very peculiar aspect.
Fig. 7 represents what appears to be the typical form, which
I have only seen in this deposit. (265.)

8. Navicula angulosa, n. sp. This very beautiful form is
frequent in the medium densities of the sand.

Form elliptic lanceolate, rather broad, with acute apices.
Length from 0:0025” to 0:0045.” Strize conspicuous, marginal,
and bounded, internally, by an angular, rhombic space. No-
dules definite, median line sharp and distinct. It is repre-
sented of the average size in fig. 8, I understand from Mr.
Bleakley, that he has found this form on our eastern coasts.

Var. 8. Rather smaller. Form linear, sides parallel, ends
acuminate, striz more distant; otherwise agreeing with a.
Represented in fig. 8*. This also seems to have occurred to
Mr. Bleakley.

Perhaps this species ought to be referred to ‘the genus
Pinnularia, but it is not easy to define these two genera. We
shall see presently that moniliform or costate striz are not
always to be depended on, although Professor Smith distin- -
guishes them by these characters. I was at one time persuaded
to refer this form to N. palpebralis, but having carefully —
studied authentic specimens of that species, I am satisfied that

Diatomaceous Sand of Glenshira. 43

they are distinct. Indeed NV. palpebralis is a very small form,
while WV. angulosa is generally large and conspicuous. But
the angular space in the middle in both varieties of N. angu-
losa, is a good and permanent mark of distinction. (266.)

9. Navicula Macula,n.sp. This is a very remarkable form,
which is not rare in the lighter densities of the deposit ; but |
have never seen it elsewhere as yet.

Form elliptic in the middle, short, contracted, and again
slightly expanding to very obtuse, almost truncate apices. In
shape it is not unlike the larger specimens of Cocconeis fiexella
( Thwaitesi?, Sm.). Length, 0:0015” to 0-002”. Median line
straight, abruptly terminating at two points some way on each
side of the centre. ‘There is no central nodule, but only a
large blank space, the length of which lies across the middle
of the valve, and which looks like a stain. Beyond this,
towards each end, the valve is very finely striated. Striz about
70 in 0001", transverse and parallel.

The peculiar blank central space, which is not at all like an
expanded nodule, differs from anything I have seen in any
other form. I have examined not less than 100 specimens,
and in none of them could I see any appearance of a central
nodule, nor could I trace the median line farther than the
margin of the blank, as we can do in so many forms where the
nodule is expanded.

Fig. 9 is a very accurate representation of this form, which
is remarkably uniform in its characters. (267.)

10. Navicula solaris, n. sp. ‘This is a very pretty and well-
marked form, frequent in the middle densities of the deposit.
It is represented in fig. 10.
~_ Form rhombic, long and narrow, with obtuse extremities.
Length from 0:0015”" to 0:0045”. The striation is fine, but
very distinct, even conspicuous, very much inclined towards
the ends, and in the centre, where there is a small circular
blank spot, so highly radiate as to present the appearance of
a sun with rays. Stria 36 in ‘O0L". The valve is usually of
a brown colour, more or less deep, even in balsam, There is
some resemblance between the shorter individuals and P. ra-
diosa; but WN. solaris, besides having finer striz, and those
more inclined, is usually much longer. As both forms occur
in the deposit, they are easily seen to differ very materially in
aspect. I have not yet observed it elsewhere. (268.)

11. Navicula Pandura, Bréb.? In the course of last year
a very beautiful form was described and figured under this
name by de Brébisson as occurring in sea water at Falaise. I
have here given under this name, as a British form, that which
is represented in fig. 11, although it does not appear to be in
all points identical with that of de Brébisson. But the Glen-

44 Dr. Grecory, on the Post-tertiary

shira sand is particularly remarkable for the occurrence in it of
several different forms of the same general type, which I figure
that they may be compared with others from different localities.

That which I have named, doubtfully, W. Pandura, is in
shape panduriform, very deeply constricted in the middle,
with the extremities nearly triangular, broad, with somewhat
acute apices. Nodule square; median line strong, double,
straight, with two dark lines, parallel to it, and close to it on
each. side, converging at the ends. These lines are shades,
caused by elevations in the striae, and similar to those in
N. elliptica, Kutz (ovalis, Sm.), and in NV. didyma. Length
0-004” to 0:005”. Striz coarse, very conspicuous, costate.
Indeed, had not de Brébisson named his form Navicula, I
should have called it Pinnularia, as the coste resemble those
of P. alpina. It will be seen that the next form has the same
character. (269.)

12. Navicula nitida, Sm.? I have named this form, repre-
sented in fig. 12, also doubtfully, as no description of the
species has yet appeared. It is represented in fig. 12. Form
like that of the preceding, but less deeply constricted, and the
ends longer in proportion. Length 0-003” or 0:004”. Striz
not quite so coarse as in the last, costate. I have been re-
peatedly informed that this is Professor Smith’s WV. nitida, but
I cannot reconcile this with his definition of MNavicula as
having moniliform, Pinnularia as having costate striae. (270.)

13. Navicula incurvata, n.sp. This form, which belongs to
the same group, is a true Mavicula, if that generic name imply
moniliform striation.

Form approaching to that of the two preceding species, but
much more gently constricted, narrower in proportion, and
with the extremities very uniformly rounded, Median line
straight, with the dark-shaded lines on each side. Striz much
finer than in the two last, about 30 in -001", and minutely
moniliform. It is perfectly uniform in its character, and a
well-marked species. Length 0-003” to 0-004”. (271.)

14. Navicula splendida, n. sp. This very fine species is also
a true Navicula, but still belongs to the same group.

Form panduriform, much constricted, very broad at the
shoulders, ends triangular and obtuse. Length 0-005" to
0-006.” Median line straight, nodule square. Strizv rather
fine, compared with the two first forms of the group; but dis-
tinctly moniliform ; not reaching the median line, and leaving
on each side of it a long narrow blank space, whiel ‘adda to ite
apparent breadth. The aspect of this form, as may be seen in
the figures, is very different from that of the other forms of the
group. It is the rarest of them in this deposit, and, as yet, has
not occurred elsewhere. (272.)

Diatomaceous Sand of Glenshira. 45

15. Navicula didyma, var. y. To the four preceding forms
I add one more, which I do not venture to erect into a new
species. It has the form and size of a very frequent form of
N. didyma, but with the entire or costate striz of Nos. 11 and
12, This character would lead us to make it a Pinnularia,
were it not that de Brébisson, and even Professor Smith him-
self, who gives it as a character of Pinnularia, have referred,
in N. pandura and WN. nitida, costate forms to the genus
Navicula. At least I am so informed as to UN. nitida, for I
have not seen Smith’s description of it, nor an authentic speci-
men named by him. De Brébisson’s figure of N. pandura
speaks for itself. |

I. have figured the costate form, which, for these reasons, I
refer for the present to N. didyma, in fig. 15. No detailed
description of it is necessary, and I need only say here, that I
frequently meet with it in the Glenshira sand, along with the
other forms of this group, ,which I have figured, and that,
besides the two common forms of WV. didyma, well figured
by Smith, our deposit contains one, if not two other varieties
which have moniliform striz, and which I refer also to NV. di-
dyma, a species which, like NV. elliptica, Kiitz. (ovalis, Sm.)
and W. elliptica, Sm. (Smithii, Bréb.), appears to vary much
both in outline and general aspect.

16. One of these is represented in fig. 16. It is frequent
in the deposit. I call it WV. didyma, 6.

It is evident that all these constricted forms belong to one
group, but how they are to be classified it is not easy to say.
The following questions naturally occur :—1. Do the costate
forms constitute one or more species? 2. Are the monili-
form types of this group to be referred to one or more species ?
3. Is it possible that all these forms, whether moniliform or
costate, belong to one and the same species? and if so, how
is that species to be defined ? )

If we refer them all to one species, or even if the form,
fig. 15, be referred to NV. didyma, or figs. 11 and 12 to Navi-
cula, what becomes of Professor Smith’s definition of Pinnu-
laria, and how is that genus to be distinguished from
WNavicula? I do not pretend here to answer these questions ;
but I may state, that the form fig. 15 has every appearance of
being a variety of WN. didyma (agreeing precisely, as it does,
in form and size with the commonest small form of that
species, which is very abundant in the deposit); and if that
be so, then we have moniliform and costate striz in the same
species. I may add that I have made observations on
N. elliptica, Kitz. (.N. ovalis, Sm.), a common fresh-water
form, which tend to show that it passes into UW. didyma,

46 Dr. GreGory, on the Post-tertiary

equally well known as a marine form.* And I have also
observed, that WV. eldiptica, which varies remarkably in all
obvious characters, sometimes acquires a nearly, if not a per-
fectly costate striation, though usually strongly moniliform.
. As I propose soon to lay these observations before the
Society, I shall not here go farther into the subject.

17. Navicula clavata,n.sp. ‘This very fine form, represented
in fig. 17, has at first sight some resemblance to N. Hennedii ;
but on close inspection, it presents remarkable characters.

Form elliptic, broad, with broad rounded projecting masses
at the apices, which are the extremities of the median line.
Striation marginal, asin WV. Hennedii, but the inner bounding
line of the striated band, instead of being purely elliptic, as in
that form, becomes towards the extremities, nearly straight,
so as to form a kind of angle, giving to the included blank
space between it and the median line, a very remarkable form.
Median line complex. First there is in the middle, as in
N. Hennedit, a narrow line proceeding from each end, and
terminating on each side of the centre, and at a short distance
from it, in long rounded expansions; the other extremities
are also rounded, but larger. Between the two central knobs
lies a rectangular white space, extending in its length at right
angles to the median line, and rather narrow. It reaches
beyond the general width of the middle part, that is, the
striated portion now to be mentioned, expands at the middle.
On each side of the proper median line is a transversely
striated band, which, near the ends, touches the median line,
but near the middle, recedes a little from it on both sides.
The striated band expands into large round heads, projecting
beyond the true elliptical outline of the valve, and it also ex-
pands a little in the middle. The white blank across the centre
appears to have at each end a small striated patch placed trans-
versely to it. The large swollen ends of the complex median
line, not only project, forming short snouts, but stand out
strongly from the surface of the valve. The strize appear rather
coarser than those of N. Hennedii, about 20 in -001", and are
very distinctly moniliform. Length of the valve, 0:0034”.

I may here mention that Dr. Greville has found in the
same Trinidad sand which I have alluded to elsewhere in this

* T observe that in Vol. II. of the Synopsis, Professor Smith gives, as
N. elliptica, Kiitz. var. 8, the form which I found in Lochleven, and which
resembles NV. didyma. I admit that it seems to be a variety of N. elliptica,
Kiitz., but I cannot find any essential difference between it and certain
forms of N. dydyma. Is it possible that N. elliptica, Kutz. may take the
form of N. dydyma in sea water, and that some other local cause may have
produced the same modification in the fresh water of Lochleven ?

Diatomaceous Sand of Glenshira. | AT

paper, and which has yielded so many fine new forms, a still
larger and finer Navicula, to which he has paid me the com-
pliment of attaching my name. In this form also, we find
the projecting, rounded, club-like snouts to the valve, standing
out from it in the same manner. It is quite distinct from the
form here figured, although, no doubt, the two forms belong
to the same group. I think I have seen, in the Glenshira
Sand, indications of a tendency in the larger forms of Navicula
Smithii, Bréb. (elliptica, Sm.), to pass into snouted varieties,
with the snout rising in relief from the surface of the valve.

1 have not met with WV. clavata, except in this deposit. (273.)

18. Pinnularia longa, n. sp. This remarkable form, of
which an. average example is represented in fig. 18, is not
rare in the deposit, but, on account of its slenderness, is
seldom found entire.

Form rhombic, very long and narrow, with acute termina-
tions. Coste very conspicuous, distant, inclined or radiate,
about 12 in 0-001". Length from 0-004” to 0-008”, but
usually about 0-006”. ‘The only known form to which it has
any resemblance is P. directa, Sm. But in P. directa, the
form is rather lanceolate than rhombic, while the striz are
much more numerous, and are also parallel, reaching the
median line, which those of P. longa, in the middle, at least,
do not reach. Moreover, P. directa, so far as I have seen, is
a much smaller form. PP. longa has another peculiarity,
which is, that the median line, as seen in the figure, is gene-
rally twisted. ‘The valve appears very thick. (274.)

19. Pinnularia fortis, n. sp. This is a very pretty little
form, and frequent in the lighter densities of the deposit. It
is well represented in fig. 19.

Form nearly rhombic, or rhombic lanceolate, rather short,
apices somewhat obtuse. Length from 0-002" to. 0:0035.
Costz conspicuous, about 16 in -001, and apparently projecting
from the surface of the valve, for on the edge view they seem
to stand out, and the valve has, in consequence, a very pe-
culiar aspect. The valve is also very convex towards the
extremities, but concave in the middle, which gives to the
F. V. a constricted form. There is a blank space at the
centre, round which the cost radiate. There is something
about the form very difficult to reproduce in a drawing.
The coste appear very distant, yet when counted, we find
them much more numerous than we expected; and if we
give in the figure the real number, the whole character of
the form is lost. This character is well represented in the
figure, but there are fewer coste there than in the original.

It is a very well-marked form. (275.)

48 Dr. Grecory, on Post-tertiary Sand of Glenshira.

20. Pinnularia inflexa,n. sp. This is a remarkably neat
little form, well marked, and frequent in the lighter densities.

Form elliptic lanceolate, ends acute. Striation conspicuous.
Coste subdistant, highly radiate, leaving in the centre a
rather large round blank space, about 26 in 0:001”. Near
each apex is a strong black cross-bar across the valve, which
I believe to be caused by a depression in the valve, and I have
named it from this character. Length 0:0014". It is very uni-
form in its characters, and is well represented in fig. 20. (276.)

21. Pinnularia acutiuscula, n. sp. This is another well-
marked species, frequent in the finer densities. Form long,
almost lanceolate, with the sides parallel in the middle, and
slowly converging to the acute apices. See fig. 21. Length
from 0:002"' to 0:0026”. Strize distinct and conspicuous in
the middle part, from being more widely separated. They
are also radiate, but less strongly so than those of the two
preceding forms. ‘They are finer than in these forms, and are
about 30 in ‘001’. The only form to which this one has any
resemblance is P. acuta, but its peculiar form and aspect are
quite sufficient to distinguish it. Both forms occur here, and
when seen together appear quite different. (277.)

22. Pinnularia Ergadensis, n. sp. I have given this name,
from Ergadia, Argyll, to the species represented in fig. 22.

Form nearly linear, or linear elliptic, ends rounded, obtuse,
almost truncate. Length from 0-002" to 0:0045", or more.
Striation finer than in P. fortis, but conspicuous ; cost about
25 in 0:001", sub-distant, not quite reaching the median line,
somewhat inclined. It is frequent in the lighter densities,
and has a perfectly distinct aspect, so that it cannot be con-
founded even with P. fortis, the form which it most resembles,
but in which the character of the striation is totally different.

As yet, I have met with none of the species of Pinnularia
here figured, except in the Glenshira sand. (278.)

23. Stauroneis amphioxys, n. sp. This curious form is not un-
frequent in the lighter densities, and is well represented in fig. 23.

Form nearly rhombic, tending to lanceolate, with acute
apices. Valve highly convex, so as very often to pre-
sent the dark appearance of an air-bubble, and, even in the
best position, showing the margin as a broad black line.
Stauras broad, reaching the margin, very transparent, so as
often to be seen with difficulty, if in the least out of focus.
At other times it is black, from the general convexity. Striz
fine, very nearly parallel, transverse, nearly 60 in 0-001”, not
conspicuous, often apparently irregular, from the convexity of
the valve. (279.)

(To be continued.)

HEnrrey, on some Fresh-water Alge. 49

Notes on some Fresu-waTER ConFERVOID Aca, new to Bri-
TAIN. By Artruur Henrrey, F.R.S., Professor of Botany,
King’s College, London. (Plate IV.)

(Read March 26, 1856:)

Panpvoritna Morum, “hr.

Pandorina, Ehrenberg (Char. emend). Frond a microscopic,
ellipsoidal, gelatinous mass, containing imbedded near the
periphery, sixteen or more biciliated, permanently active
gonidia, arranged in several circles perpendicular to the long
axis of the frond. The gonidia, almost globose, with a short,
beak-like process, a red spot, and a pair of cilia which pro-
ject through the substance of the frond to form locomotive
organs upon its surface. Reproduction—1l, by the conversion
of each gonidium into a new frond within the parent mass ;
and 2, by the conversion of the gonidia into encysted resting
spores, which are set free, and (?) subsequently germinate to
produce new fronds.

P. Morum, Ebr. (P1. IV., figs. 1-25.) Fronds hyaline; from
about 1-80” downwards. Gonidia either sixteen, and then
arranged in four circles of 4, or thirty-two, and then in five
circles, three at the poles of 4, and the intermediate three
of 8 gonidia, which in the perfect form stand near the peri-
phery and wide apart. In the forms which produce the
resting spores, the gonidia are crowded together in the centre.
The gonidia are green, but the contents of the resting spores,
after they have become encysted, are converted into oily and.
granular matter of a bright-red colour.

The description of Pandorina given by Ehrenberg, is so
incorrect, that no one would be able to determine the organism
by its aid; but the figures in the ‘ Infusionsthierchen, al-
though rude, are sufficient for identification. Pandorina
Morum has been observed by Focke* and Alex. Braun in
recent years, who pointed out the errors of Ehrenberg in
stating that the gonidia had only one cilium and no eye-spot ;
but we do not anywhere find a clear and satisfactory account
of this creature. It was with much satisfaction that we re-
ceived early in February of this year (1856), from H. Pol-
lock, Esq., a bottle containing a vast quantity of Pandorina
Morum, which he had found colouring the water in a pool at :
Hatton, near Hounslow, Middlesex.

* «Physiolog.’ Heft., ii. 1854, Pl. 1V.
t+ ‘ Verjungung,” Ray Society’s Vol. for 1853, pp. 169, 209.

50 HeEnrrey, on some Fresh-water

The forms presented by this organism are exceedingly varied,
and nothing can be more beautiful than a number of them
revolving slowly on their long axes in a drop of water, as
seen under a power of about 100 diameters.* In the first
place, the perfect form exhibits two patterns shown in figs. 1
and 3, and there are minute counterparts to these, remain-
ing in that state, as in figs. 7 and 9; while in the water
where the species is actively multiplying, all sizes between
figs. 13 and 14, just emerged from the parent frond, and the
full grown from figs. 1 and 3, &., occur. The form with
32 gonidia results from the cell-division going on one stage
further than in the form with 16; but this difference is fixed
during the earliest stages of development, as the form with 16
(fig. 1) never changes into that with 32 (fig. 3), after it
has become free from the parent. In the perfect forms the
gonidia are arranged near the periphery of the frond in circles,
like the equator and parallels of latitude on a globe, so that
Pandorina resembles Cohn’s Stephanosphera{ more closely
than any of the other Volvocinee, that having a single equa-
torial ring of gonidia in its globular frond. Among the
forms with the isolated gonidia occur others almost equally
numerous with the gonidia collected together into berry-like
heaps (figs. 15-20); these are smaller than the others, but
equally varied in dimensions ; their gonidia resemble those of
the other form; they appear destined to form the resting spores.

The gonidia are almost globular; they have no proper
membrane, but consist of a gelatinous, granular substance
which contains a thinner fluid in the centre, as it contracts
strongly by exosmosis when strong saline solutions are ap-
plied. There is a large, nucleus-like body (the chlorophyll-
vesicle of A. Braun) at the posterior end of the gonidium
(fig. 5), and at the opposite side is a short beak-like process,
with a colourless space behind it; the pair of cilia arise here,
and a little to one side and below these is the reddish-brown
granule called the ‘ eye-spot. We have never been able to
observe a pulsating vacuole, as described by Busk and Cohn
in Volvox and Gonium.

The gelatinous frond appears to be perfectly homogenous,
without any boundary membrane. Jodine and sulphuric acid
do not colour it blue. It is tolerably resistent, and appears
solid, as it does not give way or become indented by exter-
nal pressure, as is the case with the hollow frond of Volwoz.

The fronds are multiplied by the conversion of the gonidia

* A. Braun says they revolve constantly to the right; but they change

the direction constantly.
+ ‘ Annals Nat. Hist.,’ 2nd Ser., x., p. 321, &c.

Confervoid Alge. : D1

into new families. If they are viewed at night, many of the
fronds may be found at rest at the bottom of the vessel (in the
daytime they assemble at the side next the light), motionless,
and with the gonidia rounded and deprived of their nucleus.
By covering up the bottle from the light, the development of
the new fronds, which naturally takes place very early in the
morning, may be retarded so as to be followed during the
morning until noon. Some of the fronds may be found with
the gonidia converted into berry-like heaps (fig. 10), others
with the gonidia already distinct (fig. 11), while many parent
fronds present the young fronds more or less regularly arranged
in the softened and expanded parent mass (fig. 12), which ulti-
mately dissolves and sets them free (fig. 13,14). They then
increase in size in proportion to the favourable conditions in
which they are placed. I have never seen anything like what
are described by Cohn in Stephanosphera as ‘ microgonidia.’*

When kept for some weeks, an increasing quantity of fronds
became accumulated at the bottom of the water, and these
chiefly of the character shown in fig. 17, but devoid of cilia;
and while many of them decayed, in others the gonidia be-
came encysted so as to form globular cellules. Left for a
fortnight, the water was found without a trace of green colour,
with merely a brownish sediment at the bottom, upon ex-
amining which, it was found to contain a large number of
berry-like: forms (fig. 17), with the gonidia not only encysted,
but with their contents converted into a red, oily, granular
substance (figs. 21-25), as in the resting-spores of many Con-
fervoids. The gelatinous frond was here almost dissolved
away, and a slight pressure was sufficient to detach and
separate the cellules, which are doubtless resting-spores, and
destined to become subsequently developed into new fronds.
This remains to be decided.

The organism thus described is a well-marked and distinct
species, very different from Volvoxz and Gonium, but approach-
ing near to Stephanosphera. The form which produces the
resting-spores, after losing its cilia, is Kutzing’s Botryocystis
Morum, Ihave met with a form like this not unfrequently,
but never before with the perfect Pandorina. Mr. Pollock tells
me that he has collected trom the same pond for some years
past, but never found Pandorina before, and yet it colours
the water green this season. Volvox seems, in like manner, to
come and go at intervals of years, its revivification from the
resting-spores depending much on external conditions.

* ¢ Ann. Nat. Hist.,? 1. c. In a letter received from Professor A.
Braun since the above was written, he speaks of the forms with small
gonidia (figs. 7—9) as the ‘microgonidial’ form. A. H., June, 1856.

VOL. Iv. mi

52 HEnFrEY, on some Fresh-water

Apiocystis Brauntana, Nageli.

Aptocystis, Nageli. Frond a microscopic, hyaline, gela-
tinous, sac-like body, attached by an attenuated base; contain-
ing numerous green globular gonidia, multiplying, during the
growth of the frond, by quaternate division, and finally breaking
out by a lateral orifice as active, two-ciliated zoospores, each
of which becomes encysted and grows up into a new frond.

A. Brauniana, Nag. (PI.1V., figs. 26 and 27.) Frond
pyriform, 1-600” to 1-25” high, the cavity filled up by gela-
tinous matter, in which are embedded the gonidia, at first few,
increasing in number with age as far as 1600, each about
1-2000" in diameter. Nigeli, ‘ Einz. Algen,’ p. 67, Pl. ii A;
Kiitzing, ‘Spec. Alg.,’ p. 208. Fresh-water ditches, &c.

A few young specimens of this little plant were observed in
January of this year (1856) in a jar of water containing
aquatic plants, brought from Wimbledon Common six months
previously. ‘The whole collection was destroyed by frost soon
after, so that the development was not followed. Nageli (0. c.)
gives the following account of it:—

“The young ‘ swarm-cells’ (zoospores) attach themselves by their
ciliated point (especially to Cladophora fracta), and become invested with
a club-shaped enveloping membrane. ‘The first division of the green
body then takes place in the direction of the axis of the vesicular envelope,
and is repeated, in A. Brauniana, alternately in each direction of space.
During this the vesicle in which the cells (gonidia) lie, continually
expands, and generally becomes very evidently pedunculated. Young
vesicles contdin a regular number of cells, namely, 2,4, 8, 16, 32, &c. ;
but the number afterwards becomes indefinite ; in largish vesicles, 1-50”
long and 1-120” in diameter, I have counted about 800; in the largest,
about 1-25" long and 1-50" thick, some 1600 cells.

“‘ The cells (gonidia) are at first uniformly distributed over the whole
cavity of the vesicle. Subsequently they generally become collected on
the internal surface of the wall of the vesicle, where they lie in one or
more strata. But the cell-division always takes place in all directions
of space, the cells situated internally advancing outwards towards the
periphery. In old vesicles the cells are sometimes arranged in rings of 8
upon the wall.

“ When the family of cells is mature for ‘ swarming,’ which may occur
at very different sizes and with very different numbers of gonidia, the
cells begin to move at first slowly from their places, and then gradually
to circulate more rapidly in and out about each other. The vesicle bursts
and the gonidia emerge by the orifice which is formed. Sometimes the
swarming is preceded by the state in which the cells are arranged in
parietal rings. ;

“The cells secrete an abundant gelatinous coating, which becomes ~
softened within the vesicle, and confluent into a structureless jelly. The
vesicle sometimes appears merely as the boundary line of the jelly; in
general, however, it may be distinguished as a distinct wall composed of
denser gelatinous substance (PI. IV., fig. 25), the internal outline of which
is always distinct and sharp, while the outer is frequently indistinct and
partly dissolved.”

Confervoid Alge. 53

The vesicle sometimes presents delicate ciliary processes on
the outside. The zoospores have two cilia, according to

Al. Braun.* They have no ‘ eye-spot.’

CLATHROCYSTIS AERUGINOSA.

Clathrocystis, Nov. Gen. Frond a microscopic gelatinous
body, at first solid, then saccate, ultimately clathrate, (frag-
ments of the broken fronds occurring in irregularly-lobed
forms,) composed of a colourless matrix, in which are im-
bedded innumerable minute gonidia, which multiply by divi-
sion within the frond as it increases in size. (No zoospores or
resting-spores observed.)

C. eruginosa. (PI. IV., figs. 283—36.) Fronds floating in
vast strata upon fresh-water pools, forming a bright green
scum, presenting to the naked eye a finely granular appear-
ance ; when dried appearing like a crust of verdigris. Gonidia
or green cells, with a distinct membrane, about 1-8000” in
diameter, leaving a hyaline border at the surface of the fronds ;
full-grown fronds, 1-50" to 15” in diameter. Microhalea eru-
ginosa, Kiitzing. (‘ Linnea,’ viii, p. 371, Pl. 8, fig. 23.)
Microcystis icthyoblabe, Kiitz., ‘Phyc. Gen. ex parte. Mene-
ghini, ‘Monogr. Nostoch.’ p. 104. Microcystis eruginosa,
‘Tab. Phyc.’ i, Tab. 8. Polycystis eruginosa, Kiitz., ‘Sp.
Alg.,’ p. 210. “ Flos Aque,” ‘Treviranus,’ Linnza, xvii.,
p- 51, Pl. 3. On fresh-water lakes.

This remarkable form does not appear to have been ob-
served hitherto in Britain. We found it in the autumn of
1855, forming a scum extending over a large portion of the
surface of the lake in the Royal Botanic Gardens at Kew.
A portion of it, brought home and preserved in a room ina
bottle of water, continued to grow healthily until the middle
of winter.

It is very well described in the paper of Treviranus above
referred to; but none of Kiitzing’s descriptions mention its
remarkable mode of growth or its peculiar form when perfect.
Apparently that author has only seen it in a dry state; it
does not agree with the definitions of the genera Microcystis
or Microhaloa ; and as the name Polycystis has been occupied
in the Fungi, we have ventured to add to the already confusing
synonymy, by giving it a distinctive and characteristic name.

The smallest fronds met with are usually roundish or ellip-
soidal, of the character shown in PI. IV., figs. 28 and 34.
When quite young they appear to be solid, but as they grow
by the multiplication of the internal gonidia, and the secretion
of gelatinous matter, the expansion takes place chiefly near the

* “Verjungung,’ &c., Ray Soc. Vol. 18538, p. 209.
f 2

o4 HENFREY, on some Fresh-water Confervoid Alge.

periphery, so that the frond becomes a hollow body (just as
the stems of Grasses or Umbellifere become fistular). ‘The
walls of the sac then give way, (figs. 29 and 30,) and as the
expansion proceeds, orifices are formed in different parts, until
the whole becomes a coarsely-latticed sac or clumsy net, of
irregularly-lobed form (fig. 31). Then this becomes broken
up into irregular fragments (figs. 32—34) of all shapes and
sizes, (giving the stratum a granular appearance to the naked
eye,) each of which recommences. the expanding growth, and
becomes a latticed frond. The internal cells are very minute,
but have a distinct margin with internal granules (figs. 35 and
36). They multiply by dividing into two or four. ‘The gela-
tinous frond always presents a transparent border or peripheral
stratum, destitute of green cells; but no boundary membrane
exists, the surface exhibiting a softened or half-dissolved
aspect. On the approach of winter the fronds ceased to in-
crease, and by degrees most of the gelatinous masses faded to
a light brownish tint, swelled up and settled to the bottom
of the water in light flocculent clouds. They appear to
become half dissolved, and to allow the green cells to become.
free, as many of the latter were found free, adhering to the
sides of the vessel ; perhaps these reproduce the fronds in the
next season. No zoospores were ever detected.

The verdigris-like appearance of this Alga when dead is
most remarkable and characteristic. While growing, in its
wet state, it is rather of a yellowish opaque green colour.

As to the systematic position of the above species, Pando-
rina belongs, of course, to the Volvocinee ; Clathrocystis is
doubtless referable to the same group as Pulmella cruenta, and
therefore to the family of true Palmellacee, which will require
to ‘be kept apart from Protococcus, and similar forms, on
account of the absence of zoospores. -Apiocystis must remain’
for the present in the heterogeneous assemblage which in-
cludes Protococcus, Gleocapsa, &c., which require much
more study before they can be satisfactorily classified.

WenuaM, on Illuminating Opaque Objects. 1)

On a Meruop of Ittuminatinc Opaque Ossects under the
Highest Powers of the Microscore. By F. H. Wenuam.

(Read March 26th, 1856.)

REPEATED experiments have shown, that it is a matter of
extreme practical difficulty to contrive any method of con-
densing light directly down upon an object, when viewed
under an eighth or twelfth object-glass of large aperture. In
the first place, the close proximity of the front lens and its
setting, will only allow a thin conical disc of light, to find a
passage towards the object, at an angle of seldom less than
100°, or at an obliquity far too great to be practically useful ;
and secondly, when the object is covered with thin glass, con-
siderably more than half the light will be lost by the reflection
from the surfaces, the rays from which enter the microscope,
and occasion an amount of glare and fog sufficient to obscure
the object; for these reasons I think that there is but little
chance of obtaining any useful result in this direction.*

The methods that I now bring before the Society are based
upon an entirely different principle, which is not applicable
to dry objects, but only to those mounted either in Canada
balsam, fluid, or any other refractive medium. An experience
of nine months warrants me in the assurance of its complete
success, as a means of investigation—objects being brilliantly
illuminated in a jet-black field, with an objective of 170° of
aperture or more.

The principle of operation consists, in causing rays of light
to pass through the under side of the glass slip upon which
the object is mounted, at the proper angle for causing total
internal reflection from the upper surface of the thin cover, which is
.thus made to act the part of a speculum, for throwing the light
down upon the under-lying objects, immersed in the balsam or
fluid.

_ As there will be no total reflection from the planes of a
parallel plate of a refractive material, it is necessary to adopt
some method for allowing the rays to enter the medium at
such an angle as to cause total reflection from the upper sur-
face. There are many methods of effecting this; those which
I now describe I have found to be the most practicable and
useful: a,a, fig. 1, is a glass slide containing objects mounted
in balsam; 6, thin glass cover; ec, is a right-angled prism

* Since the above, Mr. Ross has shown me his ingeniously-contrived
Leiberkuhn, applied to the highest powers for illuminating wncovered
opaque objects, and which performs most admirably ; to my mind un-
doubtedly proving the fact, that the minute scales from the wings of
butterflies, &c., are perfect cellular structures.

56 Wenuam, on a Method of

cemented on to the under surface of the slide with Canada
balsam ; d, is an Amici prism for condensing and directing
the rays into the prisin c; e, is a large bull’s-eye condenser
placed with its convex side towards the lamp.

Fig. 1.

Making ample allowance for all possible differences of
refraction in the slide, balsam, and cover, the angle of total
reflection for the mean refrangible ray, will vary from 40° to
45° from the perpendicular—at any rate it will never exceed
the latter degree ; consequently for this reason I consider the
right-angle prism the most convenient for most purposes, as the
rays may be passed perpendicularly through its surfaces with-
out any trouble arising from refraction.

The mode of action illustrated by the diagram is simply as
follows: the rays from the luminous source are first collected
and converged by the large bull’s-eye lens e, and then further
condensed and directed upwards by the Amici prism d; they
next enter the surface of the right angle prism e, and pass
directly onwards till they reach the upper side of the thin
cover, from whence they are totally reflected down again,
forming a brilliant surface of light, which will of course illu-
minate any small bodies immersed in the balsam just below.
If the cover is clean and free from scratches, not the smallest
portion of light from the luminous source will find its way
through. The view of the objective will be unimpeded, and
the field perfectly black. Another way of causing the light to
enter the prism, is by means of a parabolic condenser, adjusted
as under ordinary circumstances ; the light will in this case
enter the two faces of the prism at the same time, which is
some advantage ; it must be sufficiently small to have some

Illuminating Opaque Objects. 57

play in the cavity at the apex of the paraboloid ; if the right-
angled faces are one quarter of an inch square, it will perform
very well. The objection to the plan just described is the
necessity of having a separate prism for every object, which,
though of advantage in some remarkable and peculiar cases, is
not necessary for all. Fig. 2 is more universal in its appli-
cations ; aa is a thin plate of brass, 5, a right angle prism let
in exactly flush with the upper surface; any smal] objects

Fig. 2.

such as animalcules, Diatomacee, pollen, &c., must be laid
upon the prism with water, and covered with thin glass; total
reflection will then occur from the uppermost surface, in the
same way as in fig. 1, and illuminate the objects in the fluid.
Any ordinary plane slide containing objects mounted in
balsam may be placed upon the plate and prism, first inter-
posing a drop of water. It is almost unnecessary to remark
that if this, or some other fluid is not interposed, the rays will
all be reflected from the back of the prism itself, instead of
passing onwards into the slide.

Fig. 3 is another method ; aa is a glass slide—under this
is cemented with Canada
balsam a lens, 0}, nearly
hemispherical, with a seg-
ment removed so as to
leave the thickness equal
to about one-third the dia-
meter of the sphere. The
flat facet of the lens is
blackened. The radius of
curvature should be about
two-tenths of an inch: the
use of the blackened facet
is to exclude all rays below
the incident angle of total
reflection. This lens is intended to be used in conjunction
with the parabolic condenser, in the manner represented by the
figure. The rays from the parabola pass through the surface of
the lens in a radial direction without refraction, and proceed
till they reach the upper surface of the thin glass cover, where
they are totally reflected and converge upon the object; the

Fig. 3.

58 Wennam, on a Method of

cover in this instance acts precisely the part of a Leiberkuhn,
with the advantage of more perfect reflection.

A lens of this description may be. let into a thin plate of
brass as in fig. 2, and used in the same, way as an aquatic
holder, the parabolic condenser always being used for concen-
trating the light. When a slide containing balsam-mounted
objects is placed above the lens, instead of using water, it is
preferable to employ turpentine, or oil of cloves; the refractive

index of the latzer being nearly the same as crown glass. The
reason for introducing this agent is because light impinging
upon the polished plane between a greater and a less refractive
medium, will always suffer total reflection at the surface of
the former, at a given angle dependent upon the relative
refrangibilities. If water is used, the angle of the illuminating
pencil will be limited to about 160°; above this, all rays will
be reflected down again by the flat surface of the lens, and
lost, as shown by fig. 4; aa represents the glass slide, with

Fig. 4.

IN

objects in balsam ; 0 is a hemispherical lens placed underneath
the slide, with water interposed ; cc, rays which pass onwards
to the top plane of the thin glass cover, to be reflected down
again upon the object: the dotted lines, dd, are the portions
of the illuminating pencil, that will be lost by being reflected
from the flat surface of the Jens—of course if a medium of
nearly the same refractive power as the glass is used, such as
oil of cloves, all this light will be transmitted and rendered
available.

Another variation in this principle of illuminating opaque
objects, is that illustrated by fig. 5: @ is a small paraboloid of
solid glass with a flat top. A black stop, 6, of the same
diameter as the apex, is fixed at the base of the parabola, for

Illuminating Opaque Objects. 59

the purpose of stopping out direct rays. This paraboloid is
set in a ring, which is screwed underneath a flat brass plate,

Fig. 5.

so as to bring the upper plane surface of the glass exactly
level with that of the plate in the manner shown by the figure.
The parabola must be sufficiently short to prevent any rays
from passing within the angle of total reflection relative to the
flat top—or the paraboloid may be cut off at the point in the
curve intersected by an angle of 45° drawn from the focus.

If a powerful series of parallel rays be sent into the base of
this paraboloid, not any of the light will find its way through
the upper flat surface. The whole will be reflected down
again into the hody of the glass. If now a piece of thin glass
is placed on the top, with a-drop of water, the greater portion
of the illuminating pencil will be transmitted to the upper
surface of the cover, and from thence totally reflected, illumi-
nating any small objects contained in the fluid. Glass slides
containing balsam objects may be placed on the apex of the
paraboloid, using an intermedium of turpentine, camphine, or
oil of cloves, in preference to water. This same reasoning also
applies when small objects are viewed directly in fluid, by
being laid on the flat top of the paraboloid, and covered with
thin glass. When the nature of the substances will admit of
it, for the purpose of obtaining greater intensity of illumina-
tion, they should be placed in turpentine or oil of cloves; in
_this case the whole of the light will be reflected from the top
surface of the cover—no separate reflection taking place from
the upper plane of the paraboloid, as with water. In using
this instrument, all that is required is to throw direct light
into the parabola, by means of the concave mirror.

Having now described some modifications of this principle
of illuminating opaque objects, as most especially adapted for
the highest powers, numerous experiments will justify me in
saying a few words as to the effect. The light may be ob-
tained of any required degree of intensity, and the field per-

60 Wennam, on the Vegetable Cell.

fectly black, with objectives of the most extreme aperture ;
some Diatomace@ mounted in balsam, are shown with a degree
of beauty and delicacy, that I have never seen equalled, and
from the lights brilliantly illuminating the prominences on the
surface, many of them wear an entirely different appearance to
the same objects seen as transparencies, and from the absence
of all irregular refraction and colour, and the purity of the
vision, the mind is impressed with the fact, that we are viewing
them under their true features, as cellular structures, and in
some instances displaying such a singular arrangement and con-
figuration of markings, in cases where I had not even suspected
them to exist, that I shall on a future occasion give some
illustrations of them. It must not, however, be expected that
all the Diatomacee can be seen by these methods, for some of
them, when mounted in balsam, are so exceedingly translucent,
that they will not hold a sufficient quantity of light, to be
viewed as strictly opaque objects.

For this method of illumination, the greatest nicety is
required in the adjustment of the object-glass, the slightest
defect in this causing milkiness and indistinctness of vision—
indeed so particular is the care required in this respect, that a
different adjustment is sometimes necessary for various parts
of the same object, in a case where it lies in an inclined
position in the balsam.

With regard to the relative merits of the three methods that
I have mentioned; for those who are already possessed of a
parabolic condenser, the preference is most decidedly to be
given to the hemispherical lens, fig. 4, set in a very thin plate
of brass, but the truncated paraboloid, fig. 5, is by itself a
most convenient piece of apparatus, readily applied and easily
managed, forming a most useful adjunct to the other.

On the VEGETABLE Ceti. By F. H. Wennam.
(Read May 28th, 1856.)

In the ‘ Annals of Natural History’ for May, 1856, there is a
notice, by Professor Henfrey, relating to my paper on ‘ Cell
Development,’ published in the ‘ Quarterly Journal of Micro-
scopical Science’ for Jan. 1856. I prefer making my reply
through the medium of the same Journal, which is accessible
to all whom the subject may concern.

The notice commences by saying :—‘ The essay contains
internal evidence of the author’s want of familiarity with the
subject treated.” It does, in all probability, contain irregu-
larities and omissions which may possibly be excused in an
inexperienced writer on these particular subjects. I pretend

Wennam, on the Vegetable Cell. 61

to be nothing more than a sincere searcher after the truth,
uninfluenced by motives of ambition or notoriety ; and it is
not fair that I should be criticised according to the same
rigid rules which would be applicable to an established pro-
fessor. As regards “‘ want of familiarity with the subject,”
I can only say, that for years past I have examined the deve-
lopment of the vegetable cell, and have been trying, without
success, to reconcile the facts that I. have observed with the
written statements of Mr. Henfrey; for it is to these, or such
as have appeared under his sanction, that I have made the
most particular reference. ‘This is my excuse for not viewing
these things through the medium of Mr. Henfrey’s eyesight,
and for falling back upon my own judgment; and I trust that
I may be pardoned for so doing. Even to this hour the cell
theory is by no means a settled question, and I would advise
those engaged in this study to form their ideas less upon a
groundwork of contending theories, and apply more diligently
and directly to the book of nature for information,

It is to be regretted that any remarks should give rise to
this form of reply, so directly out of the course of correct
scientific discussion. I will now proceed to notice Mr. Hen-
frey’s objections, which are scanty enough. He first says, in
reference to me:—“ The objects selected were unfavourable,
and not favourable as he imagined ; for young leaves of most
flowering plants, in the stages figured by him, are not flat
plates, but cones, or at all events solids having more than
one thickness of cells in all three dimensions ; therefore the
view is confused by one layer lying behind another.” In
reply to this I may say, that if Mr. Henfrey had condescended
to read my paper before thus perverting my meaning, he would
find these subjects described as “ cellular-cones,” or “ nodules
of protoplasm filled with cell-cavities ;” so that this objection
must at once fal] to the ground: and to avoid the delineation
of that confusion he mentions, I had drawn directly with the
camera lucida the top layer of cells only, and any error in form
and position is a trifling one, occasioned by the object being
slightly flattened in the compressor.

Mr. Henfrey further remarks :—‘‘ But even in the leaves
of Anacharis the application of dilute sulphuric acid and
solution of iodine suffices to render the structures clearly dis-
tinguishable, as quite different from what is represented in
Mr. Wenham’s drawings.” No doubt of it! I believe that
there are but few recent vegetable structures that would
submit to such treatment unchanged. I have tried numerous
experiments with these and other re-agents, but ceased to place
much confidence in them for the investigation of very young

62 Wennam, on the Vegetable Cell.

cells ; for, though they are most useful for testing the transi-
tion stages between protoplasm, starch, and cellulose-layers;
&e., they are extremely prone to develop an appearance of
saan brawies and organisms that do not really exist. I much
prefer, when the case will admit of it, to view the structure
and note the successive stages of development under natural
conditions. I am, however, far from wishing to disparage the
valuable test referred to. The effect of sulphuric acid and
solution of iodine, in the young cells in the cases in question,
is to cause the cavities in the formative plasma to become
more distinctly apparent, as perfectly clear spaces, containing
nothing else but a watery fluid. The objection that I have
sometimes found in using it is, that in the boundary of a
consolidated plasma, known to be homogeneous, it is apt to
develop the appearance of layers, or zones, not arising from
cellulose deposits, but caused by the grades of chemical
action of the test. When young cells contain but a small
quantity of contents, another fallacy may arise, from the
application, for they become drawn together in the centre of
the cavity, appearing as a ball of nucleus,

As a further explanation, which must be considered supple-
mentary to my former paper, I have now some additional
remarks to make on vegetable cell development.

The basis of a cellular structure in its first stage,—consist-
ing of a membranous sac filled with an uniform plasma, or
mass of formative material,—may be termed by some, “ the
primordial cell ;” but in my view improperly, for the external
membrane is merely protective, it exerts no active influence
upon, and is unconnected with the subdivision, or cellulation
of the contents, and, taken as a whole, has none of the func-
tions of an individual cell.*

Now we have here a vesicle filled with formative material,
ready to break up into a group of cells. Those who have
examined for themselves with the requisite degree of care
must recognize a simultaneous development,t numerous rudi-

* When the cuticular envelope, containing the uniform plasma, is
ruptured under water, the protoplasm sometimes escapes as a globule,
which speedily becomes filled with vacuoles. ‘These rapidly enlarge and
increase in number, till the whole becomes spread out and diffused in the
fluid. The tunic, or envelope of young cells, does not at first, in all cases,
possess an uniformity of surface; for, in many plants it is spinous, or
covered with tubercules, at its earliest. stage ; these are the rudiments of
hairs. It is remarkable at what an early - period they are perfectly deve-
loped, even before a definite or complete cellulation of the plasma, that
they have sprung from, has taken place; some of the hairs being already
jointed, and showing sap-currents in their cells.

+ When the bark is stripped’ from the growing branches of exogenous
plants, early in the spring, the surface of the wood is covered with a slimy

WenuaM, on the Vegetable Cell. 63

mentary cell-cavities appearing spontaneously throughout the
mass at the same time, and increasing independently of each
other; in every one the inner lining of each space in the
formative protoplasm becoming hardened into a membranous
layer, which may be readily proved, as the unconnected cell-
sacs can be washed out of the containing plasma and isolated.
The ‘ vacuoles” are rather apt to take their rise from the
larger particles contained in the plasma, but I believe that
this is only a mechanical and not a vital condition, for it is
equally certain that a large number of them form themselves
apparently without any starting point whatever. In Anacharis,
and many other plants, these cells, in the first stage of their
existence, are simple membranous sacs, containing nothing
else but a limpid, watery fluid, and a few very minute granu-
lar bodies adhering to the cell-wall—and here is a point at
issue. It is maintained that cells, even in their very earliest
stage, contain an active nitrogenous layer lining the interior
of their cavities—the so-termed “ primordial utricle.’ My
own observations cannot confirm this; and, indeed, reasoning
independently of the evidence of eye-sight, it seems an
anomaly to expect a detached portion of a material to be
enveloped in a cavity of its own substance, before any limitary
membrane is completely formed to prevent their coalescence.
Neither can it be set down as a general rule, that new cells
are commenced singly around a collection of solid contents,
for *‘ vacuoles” are to be seen of the minutest size, which are
afterwards expanded, so as to become perfect cells in all
respects; unless in this case it is assumed that the formation
takes place around invisible contents.

As I have before stated, it is not until the rmeHAbIRTD of the
sac is completely formed, that protoplasm is found within the
cell; this is rapidly followed by the deposit of internal

film of protoplasm, in a free state; if this is scraped off it will be found
to contain transitional cambium cells, dotted ducts, &c., in all stages of
development. The formative plasma is mostly deposited in the form of
strips, in the grooved surfaces of the bark and wood, and there rapidly
resolves itself into a row of cells, or hardens into a fibr e, according to the
influences of local conditions, or ‘the size of the matrix. These cells are
not formed by the division of older ones, but arise directly from the
simultaneous cellulation of the formative plasma, in the manner that I
have explained in other instances.

From the light colour of the substance it is a difficult matter to investi-
gate the young cellular deposit, as an opaque object ; but after the surface
has dried, an impression may be taken with black sealing-wax, which will
also sometimes bring away some of the young cells in course of formation,
and afford a more satisfactory view of the cell stages and arrangement,
using a Leiberkuhn for illumination.

64 Wenuam, on the Vegetuble Cell.

secondary layers, and the appearance of other constituents,
as starch, chlorophyll, &c.

The sooner the term ‘ primordial utricle,” as applied to
the active nitrogenous Jluid, or protoplasm, flowing round the
interior ofthe cell-cavities, is discarded the better, for a clear
understanding of its all-important properties as the formative
principle. If even a viscid fluid can be endowed with the
properties of a membrane, it is not at all times so in this
case, as it frequently collects in the form of clots, or nuclei
(as some might term them); thus changing its name and
appearance perhaps several times during the course of a day.

The specimens drawn for illustrating my last paper origin-
ated in a plasma so homogeneous and free from all extraneous
matters, that the cell-cavities were clear from first contents ;
in fact, this is mostly the case with Anacharis and some other
aquatic plants ; the cellulation occurring in a mass of proto-
plasm nearly pure ; but this is not so in other instances.

What I have already said of cellular formation might serve
as a guide to the principle to which my investigations have
led me, but it may now be proper to notice some frequent
variations, which at first sight might not appear reconcilable
to my views: I refer to tissues originating in a mass of cells,
not hollow at their commencement, but with their cavities
completely filled with contents (and hence I have always
hesitated in making use of the general term “ vacuoles”).
This condition is easily observable in some leaves and germi.
nating seeds, where the formative substance contains a larger
quantity of extraneous matter; under such circumstances the
process of cellulation is in no way different, for relieving the
mind from the task of attempting to reconcile the theory of
the subdivision of an unity (and the relationship of “ mother
and daughter cells”), and admitting the principle of a simulta-
neous development of cells, the denser granulated material of the
original plasma, in its first stage of cellulation, is shown to
arrange itself in the form of irregular squares, trapeziums, or
oblong figures, partitioned off by thick divisions of more
transparency and consistency. This is the true protoplasm,
which has separated from its solid admixtures, or expanded
from centres, as it were, to form the cell walls, a process to
which Dr. Carpenter has so appropriately applied the term
‘¢ differentiation ;”’* but it must not be supposed that these

* This term is also explanatory of the formation of the simplest types
of shell, which have arisen from a plasma containing calcareous matter.
The “sarcode” (analogous in vital properties to vegetable protoplasm)
having separated into somewhat irregular divisions, and formed a mem-

brane between the nucleated and consolidated calcareous matter, producing
a rude cellular structure. In some more perfect developments of shell

Wenuam, on the Vegetable Cell. 65

rudimentary walls, or rather septa, become one uniform and
continuous solid—the true cell wall is still formed in the
interior of each cavity, with the appearance of being moulded
upon the mass of contents, and when the membrane has
acquired consistency, the proper cell constituents arise within,
from external absorption as in former instances. The cells
may now be washed out from the intervening plasma in
which they are imbedded, as separate sacs just in the same
way as | have described before.

The expanding action of the living protoplasm, may be
seen in actual operation during the conjugation of the
Desmidiee—a process that Ihave always watched, with never-
failing interest. When the two masses of endochrome are
ejected, they are not bounded by any limitary membrane as
some seem to suppose, but unite at first oftentimes in the
form of a rugged mass. All the intervening protoplasm now
separates from the general mixture, and forms an external
sheath, which hardens into a membrane—the cell wall of the
unicellular sporangium.* I bring this forward again, because
the expansive effect of the protoplasm, as seen to take place
here, will illustrate the action in the associated cells in
question, when filled with contents, by considering each cell
in the formative plasma for the time being, as a separate and
independent organ.

If now one system of cells are first formed with empty
cavities, and another with more or less of primary contents,
the question arises, what ought to be the physiological differ-
ence in favour of the subsequent vital welfare and develop-
ment of the latter? As far as my investigations have gone I
cannot say that the full cells appear to differ much in growth,
or derive after benefit from the circumstance of their first
replete condition, the well-doing of the cell still depending
upon external conditions ; but without going so far as to state

structure, there seems to be a beautiful combination of this vital action, in
conjunction with definite chemical arrangement, or a crystallization of the
calcareous deposit, giving rise to very regular and perfect cellular forms,
and prismatic structures. It would be a very interesting inquiry to ascer-
tain how far these two forces act together in harmony, in forming regular
cell arrangements in other departments of the animal and vesetable king-
dom. ‘This would be an investigation in which the polariscope would be
extremely serviceable.

* In some of the Desmidiece and Algce, when the endochrome or con-
tents of one cell are forced out, by the application of gentle pressure, into
the water, the first action is somewhat similar to that which takes place
during conjugation. The protoplasm separates from the other consti-
tuents, and is determined outwards as a complete envelope, the mass ac-
quires a spherical shape, and remains so for many hours, but no consis-
tent exterior membrane is ultimately formed ; all vital action ceasing at
this point, the mass always proving barren.

66 Wenuaw, on the Vegetable Cell.

that the primary contents are useless for the purposes of
nutrition, | will merely mention that some recent and most
valuable practical researches, made by an independent ob-
server (and which [ trust he will shortly bring before the
public), have proved that extraneous matters may be conveyed
into the mass of the formative plasma, and substituted for the
contents of the primary cells, without interfering’ with the
growth, and of such a nature as to afford no nutriment to their
tissues.

In conclusion I beg to inform the Society, that though the
microscope has led me to take up particular views of cell
development, | do not profess to write a complete essay on
the subject. 1 will, however, remark, that it is still quite a
new field for investigation, for all the controversies and con-
tending theories that for years past have appeared on this
theme have done but little towards the enunciation of a
simple system of laws. As cell formation undoubtedly takes.
place, in various grades of complexity, the lowest and highest
being widely different in their mode of production, in order
to simplify this most important branch of science, I would
venture to suggest, with all due deference, the possibility of
classifying the subject, by arranging it in heads or depart-
ments, or to make myself understood, say as follows :—

1. Spontaneous appearance of membranous cavities in
a primitive plasma, or simple differentiation.

2. Cell formation by self-division, or the conjunction of
definite membranes or utricles.

3. Cells requiring special organs for their production.

4, Allied phenomena, &c.

If this were accomplished it would save some amount of
confusion; much of what is already known might be arranged
under such heads as these. In the most highly organised
plants, it is probable, that all these modes of cell formation
separately exist, in varlous organisms.

It is to after influences, or vascular bundles arising from
the parent stem, that the proportions of symmetry and form
are conveyed to the embryo cellular mass, dividing, distribut-
ing, or increasing it according to its destined condition. At
the time that these vessels and ducts begin to force their way
through the young assemblage of cells, these differ so much
in both individual form and arrangement, as to be typical in
nearly all cases of the most excessive irregularity (the embryo
leaves of the vine may be taken as an average example), and
is utterly irreconcilable with the idea that the cavities or cells
originate from the regular division and subdivision of pri-
mordial cells.

TRANSACTIONS OF MICROSCOPICAL SOCIETY.

DESCRIPTION OF PLATE I., Vou. IV.
Illustrating Mr, Wenham’s Paper on the Vegetable Cell.
Fig.
1.—End of stalk of Anacharis alsinastrum. 6, b. Germs of future leaves.
2.—Primitive cell-formation of leaf of Anacharis.

3o.—Primitive cell-formation of Arabis albida, with the rudiments of cells
appearing at the apex.

4.—Leaflet of Arabis, with cells in a more advanced stage.

5.—Malformed stellate hair with the protoplasm at the apex, showing
a tendency to cell-formation.

6.—Leaflet of Reseda burst at the apex. The exuded mass of protoplasm
having become filled with cavities.

7.—Primitive cell-formation of leaf of Anethum Feniculum.
8.—Cells of Anacharis in succeeding stage to Fig. 2.

9,—Cells of Anacharis in more advanced stage. a. a. Septa of protoplasm
dividing cells too much elongated into two parts.

10.—Cell excessively elongated with an intermediate mass of protoplasm,
a. Cavity formed in protoplasm which expands and divides the
original cell-space into three parts.

11.—Cells of Anacharis in latest stage of growth.

12.—Group of embryo flowers of Arabis albida. a. b. c. d.e. f. g. Succes-
sive stages of development. h. Cell prolongations or rudiments of
stellate hairs.

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TRANSACTIONS OF MICROSCOPICAL SOCIETY.

DESCRIPTION OF PLATE IV.,

Illustrating Professor Henfrey’s paper on some Fresh-water Con-
fervoid Algee, new to Britain.

Bye Figs, 1—25, Pandorina Morum, Ebr.
Fig.

&
1 —Perfect form, with 16 gonidia, side view.
2.—Ditto, polar view.
3.—Perfect form, with 32 gonidia, side view.
4,—Ditto, polar view.
5.—A gonidium, side view.
6.—Ditto, from above.
7 and 8.—Side and end view of a small onc with 16 gonidia.
9.—Side view of a small frond, with 32 gonidia.
10.—A frond, with the gonidia dividing.
i1.—A more advanced frond.
12.—A frond, with the young ones nearly perfect.
13 and 14.—Young fronds free.
15 to 20.—Side and end views of fronds, with the gonidia pushed close
together.
21.—Side of a frond, like fig. 15, with the gonidia encysted, their contents
turned red, and the gelatinous envelope nearly dissolved.
22.—HEind view of the same.
23.—Side view of one with 32 gonidia, more magnified.
24.—Resting-spores (encysted gonidia) free.
25.—One more magnified, to show the membranous coat.

Figs. 26 and 27, Apiocystis Brauniana, Nageli.

26.—A half-grown frond.
27.—Green conidia from the interior, the lower ones dividing.

Figs. 28—36, Clathrocystis ceruginosa, Henfrey.

28 to 31.—Successive stages of development of a frond.
32 to 834.—Fragments of a broken-up frond, like fig. 31.
35.—Green cells from the interior of the ‘gelatinous fronds, some under-
going division.
36.— One more peemicd, to show the membranous coat.

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TRANSACTIONS OF MICROSCOPICAL SOCIETY.

DESCRIPTION OF PLATE V.,
Illustrating Dr. Gregory’s paper on the Glenshira Sand.

Fig.
1.—WNavicula rhombica, n. sp. A frequent variety ; 8. V.
*— ,, sy Front view, showing several grouped in a pack.

2.—N. maxima, n.sp. 2*.—Ditto, narrow variety. 2**.—Intermediate
form of NV. maxima.
3.—LN. Hennedyi, Sm. (Not figured in Synopsis, vol. ii.)
4.—N. latissima, n. sp. 4*.—Ditto, longer variety.
5.—WN. quadrata, n. sp. (= N. humerosa, Bréb.)
6.—. formosa, n. sp.
7.—N. pulchra, n. sp.
8.—N. angulosa, n. sp.
8*.— 6 B.
9.—N. Macula, n. sp.
10.—W. solaris, n. sp. 2 figures.
11.—WN. ? Pandura, Bréb, (?).
12.—N. ? nitida, Sm.
12*.— ?
13.—WN, incurvata, n. sp.
14.—N. splendida, un. sp.
15.—WN. didyma, y. Costate striz.
16.— - , 5. A new variety.
17.—N. clavata, n. sp.
18.—Pinnularia longa, 0. sp.
19.—P. fortis, n. sp.
20.—P. inflexa, n. sp.
21.—P. acutiuscula, n. sp.
22.—P. Hrgadensis, n. sp.
23.— Stwuroneis amphioxys, ni. sp.

The figures in this plate represent, for the most part, full-sized or large
individuals under a power of 400 diameters. No. 9, Navicula Macula, is
represented under a somewhat higher power; but I believe there are
individuals of equal size under 400 diameters.

’ The remainder of the new forms which I have described in the Glenshira
Sand, and several of which are very curious, will be figured in the next
Number of the Journal.

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INDEX TO TRANSACTIONS.

VOLUME IV.

A. .
Address of the President of the

Microscopical Society, 17.
Algee new to Britain, 49,

‘iB.
Beale, Lionel, M.B., on a simple

form of portable microscope, with
lever adjustment, 13.

C.
Cell, vegetable, Mr. Wenham on, 60.

-" D.

Diatomaceous sand of Glenshira, 35.

G.

Greville, Dr. R. K., drawings of dia-
tomacee, 35,

Gregory, Dr. W., on the post-
tertiary diatomaceous sand of
Glenshira, 35.

Glenshira, diatomaceous sand of, 35.

H.

Henfrey, Arthur, Notes on some
fresh-water Confervoid Algee, new
to Britain, 49.

16

Illuminating opaque objects, Mr.
Wenham, on, 55,

M,

Microscope, portable, on a simple
form, with lever adjustment. By
Lionel Beale, M.B., 13.

Microscopical Society, Address of the
President, 17.

- Report of the

Sixteenth Annual Meeting of

the, 15.

R.

Report of the Sixteenth Annual
Meeting of the Microscopical So-
ciety, 15.

S.

Sand, diatomaceous, of Glenshira, 35.

WV.

. Vegetable cell, on the formation and

development of the; By F. H.
Wenham, 1.

W.

Wenham, F. H., on the formation
and development of the vegetable
cell, 1.

‘s oa on a method of
illuminating opaque objects, 55.

si ea on the vegetable

cell, 60.

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