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QUARTERLY JOURNAL

MICROSCOPICAL SCIENCE.

QUARTERLY JOURNAL

MICROSCOPICAL SCIENCE,

EDITED BY

EDWIN LANKESTER, M.D., F.R.S., F.L.S.,

GEORGE BUSK, F.R.C.S.E., F.R.S., F.LS.

VOLUME IL.
With Woodcuts, Lithographic and Photographic Plates.

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

INDEX

TO JOURNAL.

VOLUME I.

A.

Achromatic condenser, on a new, by
G. L. Riddell, 237.
Actinophrys Sol, description of, by A.
Kolliker, 25, 98.
Animalcule new, on a, 295.
Animaleules red, in food, 144.
Arachnida on the circulation of the
blood in, by Emile Blanchard, 279.
Ascidians, existence of cellulose in the
tunic of, 22.
- microscopical and chemical
examination ofthe mantle of, 34,106.
Ayres, Dr., P. B., on certain pecu-
liar structures in the placenta of the
bitch, 299.
53 on Vibriones, 300.
Aymot, T. E., on the “finder,” 303.

B.

Barry, Dr. M., on muscular fibre, 240.
Beale, Dr. L., on the construction of
cells for preserving objects in fluids,
54,
= on substances of extraneous
origin in urine, &c., 92.

Bennett, Dr., on leucocythemia, re-

view of, 130.
5s an introduction to clini-
cal medicine, review of, 223.

Binocular microscope, notice of, 236.

Bitch, certain peculiar structures in
the placenta of, 299.

Bird, Dr. Golding, remarks on the
preparation of the polypidoms of
zoophytes for microscopical exami-
nation, 85.

Blanchard, Emile M., observations on
the circulation of the blood in
Arachnida, 279.

Blood human, occurrence of nucleated
red corpuscles in, 145.

Bothrenchyma, on the formation of,
Dr. T. Inman on, 57.

Branchipus stagnalis, 277.

Bridgman, W. K., on the “finder,”
303.

Brightwell, T., on the genus Tricera-
tium, with descriptions of figures of
the species, 245.

VOL. I.

British Association, Belfast Meeting,
‘Sept. 1852, 61.

Busk, catalogue of marine polyzoa,
notice of, 136.
» on the oceurrence of nucleated
red corpuscles in human blood, 145,

Cc.

Cells for preserving objects in fluid,
new method of constructing them,
Dr. L. 8. Beale on, 54.

Cellularia avicularia, 87.

Cephalopoda, retina of the, 269.

Chemistry, physiological atlas of, by
Dr. O. Funke, notice of, 137.

Chirocephalus diaphanus, 277.

Clubfoot, Quekett on the condition of
the muscles in. 130,

Cobbold, Dr. T. S., on the embry-
ogeny of Orchis maseula, 90.

Cornea of the eye in insects, remarks
on by J. Gorham, 76.

Cryptococcus glutinis, 235.

Ctenoglossa, 171.

Cynthia microcosmus, 107.

Colouring matter in animals identical
with the chlorophyll of plants, 278

D.

Dactyloglossa, 173.
Daphnidz, physiological remarks on
by Dr. W. Zenker, 273.
Dentine, certain appearanees in, by S.
J, A. Salter, 252.
Diatomacez, synopsis of the British
by Rey. W. Smith, notice of, 225.
FP 5 some new forms
of, by Mr. Shadbolt, 311,
Didemnum candidum, 107.
Dotted tissue, on the formation of, 57.
Diatomaceous earth, found in the
Island of Mull, Dr. W. Gregory on,
242.
Diatoma elongatum, 21.
i vulgare, 21.
Drapernaldia glomerata, 20.
Drepanoglossa, 172.
Drinking waters, microscope as a test
of the purity of, 60.
2A

314

EK.

Echinococcus veterinorum, the true
structure of, T. H. Huxley on, 239.

Encephaloid tuberculous deposit, the
microscopic characters of, 127.

Eyes of insects, the cornea of, J.
Gorham, M.R. CS. E., on, 76.

F.

‘‘ Finder,” description of -by J. Tyr-
rell, 234.
= by E. G. Wright, 302.
- by T. E. Aymot, 303
EF by W. K. Bridgman, 304.
Flustra foliacea, 86.
;» truncata, 88.
Funke, Dr. O., atlas of physiological
chemistry, 137.

G.

Gemellaria loricata, 86.

Geranium, structure of the epidermis
of the petal of, 56.

Glass, thin, for covers, G. Jackson
on, 141.

Goitre, excess of colourless corpuscles
occurring in cases of, 176.

Gold-dust under the microscope, 144.

Gomphonema cristatum, 21.

curvatum, 21.

Gorham. J., remarks on the cornea of
the eye in insects, 76.

Gosse, P.H.,on thestructure, habits,and
development of Melicerta ringens,71.

Gray, Dr. J. E., on the teeth on the
tongues of Mollusca, 170.

Gregarine, on the, by Dr. F. Leydig,
206.

<a descriptions of various spe-

cies of, 211.

Gregory, Dr. W., notice of a diatoma-
ceous earth found in the Island of
Mull, by, 242.

H.

Hair, human, and of animals, M. A.
Morin on, 136,

Halecium halicinum, 88.

Hamiglossa, 172.

Hannover, Dr. Adolphe, on the con-
struction and uses of the microscope,
review of, 284,

Harvey, Dr, W.
review of, 280.

Henfrey, A., on vegetable cells, 233.

on the vinegar plant, 235,

a translation of Mohl on
vegetable cells, review
of, 287.

H., Sea-side Book,

INDEX TO JOURNAL.

Herapath, Dr., on optical properties
of a salt of quinine, 57.

Herbst, experiments on the transmis-
sion ‘of intestinal worms, 209.

Highley, S., Jun., description of achro-
matic gas-lamp, 143.

on the practical appli-
cation of Photography to the illus-
tration of works on Microscopy,
&c., 178.

microscope camera, 306.

Histology, lectures on, by Quekett,
notice of, 40, 122.

Holland, Dr. T. oe excess of the colour-
less corpuscles. of the blood (Leu-
cocythemia) occurring in cases of
goitre, 176.

Huxley, T. H., on the existence of
cellulose inthe tunic of ascidians, 22.

* on the development of
the teeth and on the nature and
import of Nasmyth’s “ Persistent
Capsule,” 149.

Lecture on the identity
of structure of plants and animals,
307.

= on the structure of
Echinococcus vetertnorum, 239.

Hydrodictyon, 233.

I, J.

Infusoria, in morbid discharges, 146.

Infusorial animalcules, history of, by
Pritchard, review of, 229.

Inman, Dr. T., on the formation of
Bothrenchyma, or dotted tissue, 57.

as on the structure of the
epidermis of the petal of the gera-
nium, 56.
4 on desquamation of pul-

monary air-cells, 58.

Insects, remarks on the cornea of the
eye in, 76.

Intestinal worms, experiments on the
transmission of, by M. Herbst, 209.

Tris, contractile tissue of, 8

Jackson, G., on thin glass-covers, 141.

Jenner, Dr. W., on a curious case of
colloid disease in the abdomidal
viscera, 126.

Jones Wharton, on muscular fibre-
cells, 9

K.

Kélliker, on muscular tissue, 9.
* Manual of Human Histo-
logy, notice of, 133.
9 Description of Actinophrys
Sol, 25, 98.
” Contributions towards a
knowledge of the lower animals,
211.

INDEX TO JOURNAL.

L.

Lacune in bone, Quekett on, 123.

Lamp, description of achromatic gas,
by S. Highley, 143.

Landsborough, Rev. Dr., popular
history of British zoophytes, notice
of, 136.

Leeuwenhoek, on the lenses of the
silkworm’s eye, 82.

Legg, Mr., on sponge sand, 311.

Leucocythemia, or white-cell blood,
by Dr. J. H. Bennett, notice of,
130.

*: occurring in cases of
goitre, by Dr. T. S. Holland, 176.
Leydig, D. F, on the Psorospermia

and Gregarine, 206.
Lister, Joseph, observations on the
contractile tissue of the iris, 8.
9 on the muscular tissue
of the skin, 262.
Liver, on the capillaries of, 231.
Lovén, on the teeth of marine Mol-
lusea, 171.
Lynceus, 276.
M.

Mackerel, teeth of, 158.

Mantell, Dr. A. G., obituary of, 148.

Melicerta ringens, the anatomy of, by
Prof. Williamson, 3, 65.

a on the structure,
habits, and development of, by P.
H. Gosse, 71.

Microscope camera, S. Highley, 306.

a the, and its application, by
Dr. H. Schacht, review of, 46.

35 on the construction and
uses of, by Dr. Adolphe Hannover,
review of, 284.

ms curiosities of, by Rev. J.
H. Wythes, notice of, 138.

- mode of determining the
optical power of a, 292.

53 binocular, Prof. Riddell’s,
304,

Microscopie plants and animals, lo-
calities of, 305.

Microscopical Society of London
1852-3, proceedings of, 61, 147, 242,
311.

3 objects, localities for
finding, 231.

= re-agents, Dr. Parkes
on, 139.

Microscopist, the, a complete Manual
of the use of the microscope, by T.
H. Wythes, notice of, 51.

Mollities ossium, Quekett on, 123.

Monas prodigiosa, 144.

Mohl, Hugo von, principles of the

315

anatomy and physiology of the
vegetable cell, review of, 287.

Morin, A., on the microscopic appear-
ances in the hair of man and ani-
mals, 136.

Morbid discharges, infusoria in, 144.

Miller, H., on the structure and func-
tions of the retina, 269.

Muscular fibre, microscopic observa-
tions on, by Dr. J. L. Prevost, 135.

5 Dr. M. Barry on, 240.

Muscles, fatty degeneration of, Que-

kett on, 124,

N.

Nasmyth’s “ Persistent Capsule,’’ on
the nature of, 149, 153.

Navicule, mode of isolating, by Dr.
Redfern, 235.

O

Obituary of Dr. A. G. Mantell.
aA Dr. J. Pereira, 243.

Objects for microscopical examination,
hints on the collecting of, 17.

Odontoglossa, 173.

Opaque objects, a new method of
illuminating, 237.

Oplatoglossa, 173.

Orchis mascula, on the embryogeny
of, by Dr. Cobbold, 90,

PP

Pamphagus, 298.

Parkes, E. A., M.D., on microscopical
re-agents, 139.

Pathological Society of London, re-
view of proceedings of, 126.

Pereira, Dr. J., obituary of, 243.

Phallusia, 23, 35, 109.

Phallusia gelatinosa, 107.

Pflanzenzelle Die, der innere Bau und
das Leben der Gewiichse, Dr. H.
Schacht, review of, 214,

Photographie delineation of micro-
scopic objects by artificial illumina-
tion, 165.

Photography, practical application of,
to the illustration of works on
Microscopy, &c., 178.

Plumularia faleata, 88.

Polypidoms of Zoophytes, remarks on,
by Dr. G. Bird, 85.

Polyzoa, catalogue of marine, by G.
Busk, notice of, 136.

Prevost, Dr. J. L., on muscular fibre,
135.

Psorospermia, on the, by D. F. Ley-
dig, 206,

Pyrosoma, 25.

316

Q.
Quain, Dr. R., on the distinctive cha-

racters between encephaloid and }

tuberculous deposit, 127.
Quekett, Lectures on Histology, re-
view of, 40, 122.
Quinine, optical properties in a salt
of, 57.
R.

Rainey, G., on the capillaries of the
liver, 231.

Raschkow, researches on teeth, 154.

Re-agents, useful in microscopical
inquiries, Dr. Schacht on, 47.

<5 Dr. E. A. Parkes on,
139.

Reports of Juries, Exhibition of
Works of Industry of all Nations,
1851, 219.

Retina, structure and functions of the,
by H. Miiller, 269.

Rhachiglossa, 471.

Rhipidoglossa, 171, 175.

Riddells, Prof., binocular microscope,
304.

Royal Society, Proceedings of, 243.

Ss.

Salter, S.J. A., on certain appearances
in dentine, 252.

Sarcina ventriculi, Dr. Bence Jones
on, 128.

Schacht, Dr. H., on the microscope
and its applications, review of, 46.

Pe the vegetable cell,
the internal structure and life of
plants, review of, 214.

a on the microscopical
and chemical examination of the
mantle of certain Ascidians, 34, 106.

Schultze, M. Max, on the identity of
a colouring matter present in several
animals with the chlorophyll of
plants, 278.

Sea-side Book, by Dr. W. H. Harvey,
review of, 280.

Serous cysts in the kidney, 128.

Sertularia abietina, 87.

3 operculata, 87.
s Jilicula, 38.

Shadbolt, G., hints on the collecting
of objects for microscopical exami-
tion, 17.

+ on the photographie de-
lineation of microscopic objects by
artificial illumination, 165,

INDEX TO JOURNAL.

Shadbolt, G. on some new forms of
Diatomacee from Port Natal, 311.

Siebold, C. T. von, on unicellular
plants and animals, 111, 195.

Skate, development of teeth of, 151.

Skin on the muscular tissue of, J.
Lister, 262.

Sponge sand, on, by M.S. Legg, 311.

AY

Teeth, development of, by T. H. Hux-
ley, 149.

Tongues of Mollusca, on the teeth of,
by Dr. J. E. Gray, 170.

Teenioglossa, 173.

Toxoglossa, 172.

Triceratium, on the genus, by T.
Brightwell, 245.

Trichina spiralis, 209.

Tyrrell, J., description of a “ finder”’
for the microscope, 234.

LOR AY

Unicellular plants and animals, C.
T. von Siebold on, 111.

Urine, substances of extraneous origin
in, 92.

Vegetable cell, the internal structure
and life of plants, &c., by P. H.
Schacht, review of, 214,

=. ona peculiarity in the
thickening layers of, by A. Henfrey,
233.

x principles of the ana-
tomy and physiology of, by Hugo
von Mohl, review of, 287.

Vibriones, 300.

Vinegar plant, the history of, by A.
Henfrey, 235.

Vortex viridis, 278.

Wa

Williamson, on the anatomy of Meli-
certa ringens, 3, 65.

Wright, E. G., on a “finder,” 302.

Wythes, Rev. J. H., curiosities of the
microscope, review of, 138.

Daa En

Zenker, Dr. W., Physiological re-
marks on the Daphnide, 273.
Zoological Society, proceedings of
1852, 239.
Zoophytes, on the polypidoms of, 85.
eA popular history of British,
notice of, 136.

PREFACE.

RECENT improvements in the Microscope having rendered that
instrument increasingly available for scientific research, and
having created a large class of observers who devote themselves
to whatever department of science may be investigated by its
aid, it has been thought that the time is come when a Journal
devoted entirely to objects connected with the use of the Micro-
scope would contribute to the advancement of science, and secure
the co-operation of all interested in its various applications.

The object of this Journal will be the diffusion of informa-
tion relating to all improvements in the construction of the
Microscope, and to record the most recent and important re-
searches made by its aid in different departments of science,
whether in this country or on the continent. A department of
the Journal will be given to reviews of works, or those parts of
works which are devoted to subjects of inquiry in which the
Microscope is employed. It is the wish of the Editors to con-
duct this department in a friendly spirit, regarding all who
labour honestly in the field of science as co-workers for the
common good. In order to gather up fragments of information,
which singly might appear to be useless but together are of
great importance to science, the Editors have opened a depart-.
ment for short notes, memoranda, and correspondence, to which
they would especially invite the attention of their scientific
friends, as they believe there are few possessors of a Microscope
who have not met with some stray fact or facts which, published
in this way, may not lead to important results. They hope
also to relieve the graver and more strictly scientific matter
of the Journal by lighter contributions, such as will be found
useful to the beginner, not uninteresting to the advanced ob-
server, and of interest perhaps to the general reader.

In a Journal of this nature illustrations are indispensable, as
it is difficult to convey an accurate idea of objects observed by
description alone ; but as it is impossible to give a fixed amount,
the Publishers have determined to afford, on an average, with

VOL, I. B

2 PREFACE.

each number, four lithographic plates, and such woodcuts as
may be necessary ; and they congratulate themselves in having
secured for this department the services of Mr. Tuffen West, as.
their artist, to whose plates in the present number they may
confidently appeal, as examples of the manner in which they
wish to illustrate the Journal in future.

In announcing the objects they have in view, the Editors
would especially call attention to the connexion of this Journal
with the Microscopical Society of London, as it is mainly
through the readiness expressed by the Council of that Society
to co-operate with the Proprietors and Editors, in order to dif-
fuse more widely, and to publish more regularly, their Trans-
actions, that the Journal owes its existence in its present form.

The papers published under the head of ‘Transactions of
the Microscopical Society of London’ are selected by the
Council of that Society ; for its other contents and general con-
duct the Editors are alone responsible.

It is, perhaps, hardly necessary to apologise for the title of
the Journal, as the term “ Microscopical,” however objection-
able in its origin, has acquired a conventional meaning by its
application to Societies having the cultivation of the use of the
Microscope in view, and so fully expresses the objects of the
Journal, that it immediately occurred as the best understood word
toemploy. It will undoubtedly be a Journal of Microscopy and
Histology ; but the first is a term but recently introduced into
our language, and the last would give but a contracted view
of the objects to which the Journal will be devoted.

As the success of their undertaking must mainly depend on
the cordial assistance and co-operation of those who are engaged
in prosecuting microscopical investigations, the Editors would
urge upon them the importance of their assistance in making
known the nature and objects of ‘The Quarterly Journal of

Microscopical Science,’ and in becoming contributors to its
pages.

QUARTERLY JOURNAL

OF

MIGROSCOPIGAL SCIENCE.

ORIGINAL COMMUNICATIONS.

On the Anatomy of Meticerra rincens. By W. C. Wit-
LIAMSON, Esq., Professor of Natural History, Owen’s Col-
lege, Manchester.

Tue appearance of large numbers of the Melicerta ringens
amongst the plants growing in my Vallisneria trough has
afforded me an opportunity of subjecting this fine Rotifer to a
careful examination; the result has been the elucidation of
some portions of its anatomy which had not been fully worked
out by Leeuwenhoek, Schaffer, Dutrochet, or Ehrenberg.

The ordinary appearance of this object is too well known to
need a description. Its general aspect, when removed from its
tessellated case, is represented by fig. 14, Pl. I. The four fla-
belliform rotatory organs (14a), when forced out of the body
(into which they can be withdrawn) and fully expanded, are seen
to be clothed with ciliz over their entire surface ; those fringing
the margin being the longest and most conspicuous. On one
side of the neck are the two small incurved processes (145),
which Schiffer calls the lips. When the animal withdraws
the rotatory organs into the fore part of its body, which it does
when alarmed, these hooks constitute two of the most prominent .
points of its body. On the opposite side to that occupied by 4
these appendages there is a fifth and smaller rotatory organ (1 ¢),
with a thickened margin, from which radiating bands proceed ~~
inwards to its point of attachment. This organ is also ciliated. \™
On each side of it, and opposite to the two hooks, there are
two long tentacles (14d), the homologues of organs which are
common amongst the Rotifera. To these Ehrenberg has
assigned respiratory functions, whilst Dujardin regards them
as more closely resembling the antenne and palpi of the
Entomostraca. When one of these tentacles in the Melicerta
is fully protruded it is seen to be terminated by a brush of
fine divergent sete (15), implanted on the convex side of a
small deltoid body (156); from the flat side of this latter

B 2

4 ON THE ANATOMY OF MELICERTA RINGENS.

appendage there proceeds along the interior of the tube,
towards the body of the animal, a delicate muscular band
(15), which, by its contractions, draws the deltoid body back-
wards, thus inverting the extremity of the tube and forming a
double sheath protecting the sete (i6). This inversion of
the tube was, I believe, first noticed by Dutrochet. The
whole apparatus is, as suggested by Schaffer, very similar to
that seen in the tentacles of the snail, and appears to consti-
tute a tactile rather than a respiratory organ. This is rendered
the more probable by the fact, that when the animal first
emerges from its tessellated case, the extremities of these two
tentacles are the first parts that make their appearance, the two
curved hooks being the next. The sete are usually half-
drawn into the inverted tentacle, but they project sufficiently
forward to constitute delicate organs of touch, supposing the
deltoid body into which they are inserted to be endowed with
sensibility. The animal cautiously protrudes these tentacles
before it ventures to unfold its rotatory organs, but it does
not direct them in an exploratory manner from side to side, as
an insect does its antenne.

The alimentary canal commences with a small oral orifice, ©
situated near the centre of the sinuated disk formed by the
rotatory organs, It opens into an cesophagus, which conducts
the food down to the gastric teeth (14e). These are implanted
in a large conglobate cellular mass, which completely invests
them. Their appearance is accurately represented by fig. 17:
they consist of two essential portions—a pair of strong crush-
ing plates, which bruise the food, and various appendages
affording leverage and facilitating the action of the muscles
upon them. ‘Ihe crushers are two broad elongated plates
(17 a), each being about 1-800th of an inch long, and separated
from each other at the mesial line, near which they become
much thickened. From each of these plates there proceed
laterally numerous parallel bars (17 0), all of which are some-
what thickened at their inner extremities where they are
attached to the plates, whilst at their opposite ends they are
united with the others of the same side by a curved con-
necting bar (17 c¢), from the outer sides of which are given off
various loops and processes, The three uppermost of these
bars are the largest, the rest gradually diminishing in size and
strength as we descend, the inferior ones being almost invisible.
From the upper extremities of the two crushers there project
upwards and backwards two slender prolongations (17d),
united by a kind of double hinge-joint near their apex,
where they not only play upon each other, but also on
a third small central fixed point (17e) lodged in a little

ON THE ANATOMY OF MELICERTA RINGENS, 5

conglobate cellular mass. Ehrenberg only describes three
transverse bars on each side, which he regards as teeth. It is
obvious that he has only noticed the three upper and larger
pairs. It is equally evident that these transverse teeth, as he
terms them, do not move upon the strong longitudinal plates,
as he imagines, but are firmly united with them. Muscles are
either attached to the divergent peripheral processes, or to the
cellular mass in which these processes are imbedded, causing
the entire apparatus to separate into two parts along the mesial
line, by means of the hinge joint at 17c, the so-called teeth
merely transmitting the motor force to the two longitudinal
plates. These latter appendages are thus made to play upon
each other with great power, and act as efficient crushers,
bruising the food before it passes into the stomach, as is the
case with the gastric teeth of the crustacea, From the above
remarks it will be seen that, though in its construction the
dental apparatus is more complex than is represented by
Ehrenberg, in its mode of working it is less so.

The conglobate organ in which this apparatus is imbedded
is transparent, and composed of numerous large cells, each of
which contains a beautiful nucleus, with its nucleolus. The
cells are only seen when the organ is ruptured between two
plates of glass, when they readily separate from one another ;
but the nuclei, with their contained nucleoli, are distinctly
visible in the living animal. Delicate muscular threads most
probably penetrate this organ to reach the dental apparatus,
though I have not yet detected them.

After passing the dental organs, the food enters an elongated
stomach (14 f), with very thick pulpy parietes. In young ex-
amples these walls are colourless and transparent, but in more
matured specimens they exhibit a bright olive-yellow hue.
The whole cavity, as well as the cesophagus leading into it, is
lined with ciliz, which are constantly playing. On rupturing
this organ we perceive that it is composed of a thin pellucid
external membrane, which exhibits no structure, but within
which is a thick layer of large turgid epithelial cells. These
are easily detached from the membrane, when each one
is seen to be spherical, containing numerous yellow granules,
and very often a nucleus with its nucleolus. The cilia are
attached to one side of these cells, the great length of these
appendages constituting the most marked feature of the struc-
ture. It often equals the entire diameter of the cell. Some
of the cells exhibit no cilia; others are only furnished with
them on one side; whilst a few appear to be fringed with
them throughout their entire circumference. I presume that
in the latter case the cells have projected considerably into

6 ON THE ANATOMY OF MELICERTA RINGENS.

the cavity of the stomach. The yellow granules are absent
from those of young animals, showing clearly that it is these
contained granules that give the colour to the parietes of the
stomach in matured individuals. The connexion between the
cells is very slight, since but little pressure suffices to detach
them from their position without marring their integrity. By
their aggregation they constitute a true epithelial structure,
lining a thin and apparently structureless membrane ; but from
the constant automatic movements of the viscus, it is possible
that this latter membrane may contain minute muscular fibrille.
The great thickness of the epithelial layer, as compared with
the entire diameter of the organ, is curious. Whilst the latter
averages about 1-250th of an inch, the former is often not less
than 1-1500th, or 1-6th of its entire diameter. The cells
when detached vary in size, from a diameter of 1-1000th to
1-1600th of an inch: one of these, which was fringed with
ciliz, 1-1600th of an inch long, is represented in fig. 18, its
nucleus being about i-7000th of an inch. After being de-
tached, some of the ciliated cells floated slowly away, like so
many animalcules.

This stomach appears to be chiefly a receptacle for the food.
From time to time, especially when the viscus is distended, a
portion of its contents pass down into a lower stomach (14 g),
which is separated from the upper one by a marked though
varying constriction. This second stomach is also lined with
ciliz, which are even longer than those of the upper viscus ;
but the parietes are very much thinner and more transparent,
the cells being less easily traced. The diameter of the organ
is nearly the same in each direction,so that it is almost sphe-
rical. The mass of food with which it is usually distended is
constantly revolving, the motion being due to ciliary action.
This process goes on for some minutes, after which the crea-
ture contracts its body, and forces the entire exuvie out of the
viscus into a long narrow cloaca, which terminates externally
by an anal outlet at 14. As it does this, it everts a consider-
able portion of the cloaca; thus almost bringing the cloacal
outlet of the stomach to the exterior, and causing at the same
time a large transparent protuberance (14 7) to be developed on
the corresponding side of its body. At other times the crea-
ture can draw in these appendages, so that scarcely any trace
of a cloacal canal is visible.

Nearly on a level with these stomachs is the ovary (14 ), an
oblong organ, extending from near the oral orifice, superiorly,
to the centre of the lower stomach in the opposite direction.
It is a pellucid membranous bag, distended with granular
protoplasm, in which are dispersed numerous nucleolated nuclei.

land

ON THE ANATOMY OF MELICERTA RINGENS. (

The oviduct consists of a prolongation of the membrane of the
ovary. It winds round the inferior border of the lower stomach
(14 7 and 19 4), and enters the cloaca near the point where the
lower stomach opens into that excretory canal.

I have sought in vain for any organ to which the functions
of a spermatic gland can be indisputably assigned. Immedi-
ately beneath the lower stomach and the contiguous oviduct,
there is an elongated pyramidal organ (14 m and 19 d), appa-
rently hollow, the thick extremity of which is directed towards
the ovary, and its opposite attenuated portion passes upwards
towards the cloaca, between the oviduct and the general inte-
gument. Into the thick inferior extremity of this organ there
are inserted, exactly opposite to each other, two long cylin-
drical appendages, which diverge, and, passing on each side of
the alimentary canal, proceed towards the upper part of the
body, where their extremities are not easily traced. In but
one instance I observed them to terminate in a series of irre-
gular conyolutions near the base of the two tentacles. Though
not yet capable of demonstration, it appears probable that
this curious appendage may be a filamentous spermatic tube,
resembling those found in many of the articulata. ‘That they
are tubes, and not muscular bands, appears unquestionable ;
and as they have obviously a direct connexion with the cloaca,
they might easily discharge a fertilisimg secretion into that
common excretory canal, from which it would find its way to
the ovary through the oviduct.

The muscular system is developed in an interesting manner.
Distinct muscular bands occur at intervals in the common
tegument, concentrically encircling the entire organism. Their
action is easily observed. Still larger and more distinct fasci-
culi run lengthwise; some of these proceed from the upper
part of the visceral cavity to the base of the tail or peduncle,
where (19) they are inserted into a thickened portion of the
integument. Others, taking their rise from various parts of
the body, proceed along the caudal prolongation (14, 19 g, and
20 a), and are inserted into a little concavo-convex body
(14 0, 20 b) at its extremity. This latter group of muscles is
easily examined, owing to the exceeding transparency of the
integument. On rupturing the muscular fasciculi trans-
versely, we perceive that each one is invested by a delicate
sarcolemma (21a). This is well seen at the upper part of the
tail, where, on the contraction of the muscle, the non-elastic
sarcolemma becomes corrugated (21 b), and only recovers its
smooth aspect when the muscle becomes relaxed. These ruge
of the sarcolemma must not be confounded with the transverse
strize of the muscular fibre. When one of these muscular fas-

Whe

8 ON THE ANATOMY OF MELICERTA RINGENS.

ciculi is drawn out at full stretch, its surface is seen to be
marked at very regular intervals by dark transverse bars (22).
Each fasciculus has a diameter of about 1-3500th of an inch,
and the transverse strie recur at distances of about 1-9000th.
These intervals are, of course, rather larger than those seen in
the fasciculi of human voluntary muscle. The bars extend
entirely across the fasciculus. There can be no doubt that
this structure is the homologue of what occurs in the voluntary
muscles of the higher animals.

The general integument consists of a thin and very trans-
parent membrane. In this are embedded numerous concentric
muscular bands already referred to. In the skin surrounding
the visceral cavity there are also longitudinal fibres ; whilst, in
the rotatory organs, corresponding threads, which I presume to
be muscular, interlace in various directions.

The small organs which are so common amongst the Roti-
fera, and which Ehrenberg regards as nervous ganglia, are
abundant in the Melicerta; but they afford no countenance
to the hypothesis of the great Prussian Professor. They
appear to be nothing more than small cells or vesicles formed
of granular viscid protoplasm, very similar to that into which,
as we shall immediately find, the yolk of the egg becomes
diyided. Sometimes they float freely in the fluid which dis-
tends the integument and bathes the viscera (14 p). At others,
thin ductile threads pass from one vesicle to another, as seen
in fig. 19 A, where these objects are delineated as they appeared
in one individual, in the clear space immediately below the
viscera. In this case they are more abundant than is usual.
There is no uniformity in their arrangement in different indi-
viduals. They differ as widely as is possible in their size,
number, and distribution. So far from being nervous vesicles,
they appear rather to be cells, modified into a rudimentary
form of areolar tissue. ‘That they are hollow vesicles or cells,
very viscous, readily cohering, and, owing to this coherence
readily drawn out by the movements of the various organs to

which they are attached, are facts capable of easy demon-
stration,
{To be continued.]

Observations on the ContrRactite Tissue of the Irts. By
Joseru Lister, Esq., B.A.

Our knowledge of the cause of the movements of the iris was
till within the last few years in a very unsatisfactory condi-
tjon. That this organ possessed contractile fibres was a
matter of inference, not of direct observation. In the third

CONTRACTILE TISSUE OF THE IRIS. 9

part of the last edition of Quain’s Anatomy, published in
1848, we find it stated (p. 915) that the radiating and circular
fibres of the iris are generally admitted to be muscular in their
nature, but the grounds for that admission are not mentioned.
Mr. Bowman’s Lectures on the Eye, delivered in the summer
of 1847, and published in 1849, show us that the then state of
histology in this country did not enable that accomplished
microscopical anatomist to identify the fibres of the iris with
other plain (unstriped) muscular tissue. At page 49 he says,
‘“* The fibres which make up the proper substance of the iris
are of a peculiar kind, very nearly allied to the ordinary un-
striped muscle, but not by any means identical with it.” He
afterwards goes on to argue that, as we know that the organ
changes its form, and as its vessels are so distributed that it
cannot be erectile, we have no other resource than to consider
its fibres contractile, which conclusion he supports by refer-
ence to the striped fibres in the iris of birds and reptiles.

In 1848 Professor Kolliker announced to the world his
grand discovery of the cellular constitution of all plain mus-
cular tissue, in a full and elaborate paper in the ‘ Zeitschrift
fiir Wissenschaftliche Zoologie.* At p. 54 of the first part
of the first volume of this journal, after speaking of the arrange-
ment of the fibres of the ciliary muscle, the sphincter pupille,
and dilator pupille, he makes the following statement :-—
** The elements of all these muscles are undoubtedly smooth
muscular fibres. In man I have but seldom succeeded in iso-
lating the individual fibre-cells, but I have had more frequent
success in the case of the sheep, where I found them in the
ciliary muscle, on an average, 1-600th of an inch in length, and
1-4000th to 1-3000th of an inch in breadth. In man, in all
these muscles one sees, as a rule, only parallel fibres projecting

* Professor Kolliker may almost be said to have been anticipated in
this discovery by Mr. Wharton Jones, Through the kindness of that
gentleman, I have now before me two original drawings, made by him
about the year 1843, of plain muscular tissue from the small intestine.
In one of these the muscular fibre-cells are characteristically shown,
except that their nuclei are not apparent; one of them is wholly isolated.
In the other drawing, the alternate disposition of the fibre-cells is seen
after the addition of acetic acid. He also observed, as he informs me, that
the unstriped muscle of the cesophagus and stomach, and also of the
uterus and other organs, consisted of similar elements—a fact which he
yearly communicated to his class in his public lectures at Charing Cross
Hospital. He was led, from appearances in the embryo, to infer that
striped muscular fibre is originally composed of similar elements, which,
. in the process of development, are enclosed in a sarcolemma common
to many of them, and become split into fibrille. He thus accounted for
the nuclei of striped muscular fibre, which, according to this view, are the
persistent nuclei of the primitive muscular fibre-cells.—J. L.

10 OBSERVATIONS ON THE

to a greater or less extent at the edges of small fragments of
the tissue, these fibres exhibiting in abundance the well-known
elongated nuclei, either with or without the aid of acetic acid.
In man, the muscle of the choroid (ciliary muscle) has broader
and more granular fibres and shorter nuclei than the iris. In
the former the nuclei measure from 1-2400th of an inch to
1-1333rd of an inch; in the latter as much as 1-1090th of
an inch.”

Here, then, we have, so far as I know, the first and only
recorded observation of tissue in the iris identical with ordi-
nary unstriped muscle. |

It is to be remarked that, where he alludes in the passage
above quoted to having in rare cases separated the individual
fibre-cells of the muscular tissue, Professor Kolliker speaks of
the three muscles (ciliaris, sphincter, and dilator) collectively ;
in other words, that he does not tell us in plain terms that he
has isolated the fibre-cells of the iris at all. Now, the ciliary
muscle is confessedly easier to deal with than the iris. Mr.
Bowman, who speaks so doubtfully of the fibres of the iris,
says of the ciliary muscle, ‘‘ the fibres are seen to be loaded
with roundish or oval nuclei, often precisely similar to those
of the best marked examples of unstriped muscle” (op. cit.,
p- 53). Another very eminent microscopical anatomist has
informed me, as the result of his experience, that it was easy
to identify the tissue of the ciliary muscle with that of other
organic muscle, but that this had not been the case with the
iris. That Professor Kolliker’s isolation of the fibre-cells of
the muscles of the eye was in reality confined to the ciliary
muscle is rendered probable by the fact that, while the whole
article quoted from shows a manifest desire on the part of its
author to give all available detail, yet regarding the iris he
mentions no facts requiring isolation ‘of the fibre-cells for their
determination ; while, on the other hand, he tells us that the
fibre-cells of the iris are narrower than those of the ciliary
muscle, and gives the length of the nucleiin the human iris—
things which are very readily observed without isolation of
the fibre-cells. His figures refer to the human ciliary muscle
alone ; and the only measurements given by him of muscular
fibre-cells from the eye refer to the same muscle in the sheep.

It would seem, then, that with regard to the iris, Kolliker’s
proof falls short of the test of isolation of the fibre-cells,

An operation for artificial pupil, by excision, performed by
Mr. Wharton Jones, at University College Hospital, on the
11th of August of the present year (1852), placed in my pos-
session a perfectly fresh portion of a human iris, and, without
knowing that Kolliker’s observations had extended to the

CONTRACTILE TISSUE OF THE IRIS. 11

muscles of the eye, I proceeded to avail myself of this some-
what rare opportunity of investigating the muscular tissue of
the human iris. On placing under the microscope, four
hours after the operation, portions of the tissue carefully
teased out in water with needles, I found that some of the
muscular fibre-cells had become isolated, and presented very
characteristic appearances. I accordingly made camera lucida
sketches of the finest specimens, which are reproduced on a
smaller scale in the accompanying figures (see PI. L., fig. 7-11).
I drew the last cell (fig. 8) 93 hours after the operation. And
here I may mention that 1 have not found the muscular fibre-
cells by any means a very perishable tissue. After an iris
has been soaking two or three days in water, the muscular
tissue of the sphincter is still quite recognisable, not only by
the nuclei, but also by the individual fibre-cells.

Of the figures above referred to, (7) and (8) are examples
of the most elongated cells that I saw. By reference to the
scale it will be found that the cell (7) is about 1-125th of an
inch in length, and about 1-3750th of an inch in greatest
breadth ; while (8) is a little shorter, but of about the same
average breadth. Kolliker divides muscular fibre-cells into
three artificial divisions, according to their shape, of which
the third contains the most elongated and most characteristic
cells. Of this third division, the cells (7) and (8) are good
examples, and, in fact, correspond in their measurements to
average fibre-cells of the muscular coats of the intestines.
The cells (9) and (10), though less characteristic in respect of
their length—(9) being about 1-333rd of an inch in length, and
1-3000th of an inch in breadth, and (10) 1-300th of an inch by
1-3000th of an inch, yet present the same peculiar delicate
appearance and soft outline, and the same elongated nucleus,
of not very high refractive power relatively to the contents of
the cell, but clearly defined. All these cells have the same
flat or ribbon-like form which is exhibited by the cell (8) at
(a), where one edge has become turned up by a folding of the
cell ; at (b) there seemed a tendency to transverse arrangement
of the granules of this cell, which tendency is more strikingly
exhibited at 5 and ¢ in the cell (11), which, though not isolated,
is introduced on that account. ‘This tendency to transverse
arrangement of the granules was long since noticed by Mr.
Wharton Jones, as that gentleman has since informed me,
and is, indeed, indicated in the drawings which are alluded
to in the note above. In the cells of this iris, however,
it was not by any means constant. Some of them, as (7) at
(a), and (9) at (a) and (b), exhibited something of a longi-
tudinal arrangement of the granules, such as was noticed some

12 OBSERVATIONS ON THE

years since in unstriped muscle by Mr. Bowman, who consi-
dered the rows of granules as an approach to the fibrille of
striped muscle. These cells are more granular than I have
found those of the iris of the horse to be; but I may here
mention that, on comparing with these drawings the outline
of a fine specimen of a muscular fibre-cell of the sphincter
pupilla of this animal, which I had sketched by the camera
lucida, { find it to be almost an exact counterpart of the cell
(7) as regards the shape and size of both the cell and its
nucleus. The nuclei of these cells measure from 1-1400th to
1-1110th of an inch in length, and about 1-9500th of an inch
in breadth. They are not, however, the most characteristic
that are to be found in the iris. Fig. 12 is from a camera
lucida sketch of a nucleus of the sphincter pupillz of a horse ;
it measures 1-840th by 1-15,200th of an inch, and exhibits in
a very marked manner the true rod-shaped figure which ap-
pears peculiar to muscular fibre-cells. On the other hand, I
found some instances in the human iris of fibre-cells with con-
siderably broader nuclei than those in the figures. The iris
that yielded these cells was a blue one, apparently perfectly
healthy ; it was active and brilliant before the operation, which
was performed on account of central opacity of the cornea,
resulting from an attack of a severe form of ophthalmia fifteen
months previously. I watched the case closely from the first,
and there was no reason to suspect implication of the iris in
the inflammation.

Having thus satisfactorily verified the fact of the existence
in the iris of tissue identical with ordinary unstriped muscle,
I was naturally led to inquire into its distribution in the
organ: and, as this is a subject of great interest, and one
about which much difference of opinion has prevailed, I may
mention here the facts which I have hitherto observed, al-
though there be not very much of actual novelty in them.

Kolliker, in the article above referred to (loc. cit. pp. 53 and
54), describes a sphincter and dilator pupille, the former
‘‘ very readily seen in the white rabbit, or the blue iris of man,
from which the uvea has been removed, about a quarter of a
line broad in man, exactly forming the pupillary margin, and
situated somewhat nearer the posterior surface of the iris.”
Of the dilator he says, while confessing the difficulty of the
investigation, that he believes it to consist of many narrow
bundles, which run inwards separately between the vessels,
and are inserted into the border of the sphincter.

Bowman, on the other hand, states (op. cit. p. 48) that,
while in some instances a delicate narrow band of circular
fibres exists at the very verge of the pupil, yet, in the majority

CONTRACTILE TISSUE OF THE IRIS. 13

of instances, he feels suve that no such constrictor fibres of the
pupil exist. He ascribes the contraction of the pupil to the
inner part of the radiating fibres, which, he says, are joined
and knotted in a plexiform manner round the pupil. It is
scarcely needful to observe that such a statement from such an
authority could not but go far to impugn Professor Kolliker’s
assertion respecting the existence of a sphincter pupilla.

My experience, I must confess, accords with that of Kol-
liker, viz. that the sphincter is readily seen, while the dilator
is that whose investigation alone presents very serious diffi-
culty. In the first iris that I examined with a view to the
distribution of the muscular tissue, | was struck, after remov-
ing the usual pigment, with the appearance of a band on the
posterior surface of the iris, near the pupil and parallel to its
margin, quite evident to the naked eye, elastic and highly
extensible. This proved to be the thickest part of the
sphincter pupilla. I have examined six human irides with
reference to the distribution of the muscular tissue, but in
none have I had any difficulty in recognising the sphincter,
which I have also found equally distinct in some of the lower
animals, viz. in the rabbit, the guinea-pig, and the horse. In
man I find it about 1-30th of an inch in width, thickest towards
its outer part, where it lies nearer the posterior surface of the
iris than the anterior, and thinning off towards the pupil,
where it forms a sharp margin, covered apparently on its
anterior aspect only by some vessels and nervous threads and
a delicate epitheliated membrane, which is thrown into beauti-
ful folds when the pupil is contracted. The fibres of the
sphincter are not absolutely parallel, and this deviation is
probably produced in part by the dilating fasciculi sweeping
in at various parts in a curved manner, and becoming blended
with the sphincter. The reason for this supposition will
appear hereafter. By teasing out under the microscope a
portion of the actual pupillary margin, I found the sphincter
to consist at this part of apparently unmixed muscular fibre-
cells, without any connecting cellular tissue. Fig. 13 is a camera
lucida outline of the edge of a portion of the sphincter so pre-
pared, which edge is seen to be formed of projecting fibre cells,
and similar appearances may be seen with great readiness under
a high power, after stroking the pupillary margin with the point
of aneedle. Indeed, the great facility with which the tissue
may be thus broken up appears opposed to the idea of the
fibre-cells being united end to end into fibres, as the descrip-
tions formerly given of unstriped muscle would lead one to
suppose. The ends appear to separate as readily as the edges
and surfaces, and it would rather seem as if the fibre-cells of

i4 OBSERVATIONS ON THE

a fasciculus were placed with their long axis in one direction,
cohering generally to one another, but without the formation
of longer fibres than each cell itself constitutes. I may here
mention incidentally that in the circular coat of the aorta of
the sheep, where the muscular tissue is disposed in_ thin
layers among the elastic tissue, 1 have observed a distinctly
alternate arrangement of the fibre-cells without any formation
of fibres. Mr. Wharton Jones’s drawing of alternately dis-
posed fibre-cells in the small intestine has been alluded to
in the note above. A portion of the outer and thicker part
of the human sphincter pupilla proved also extremely rich
in muscular fibre-cells. In the rabbit and guinea-pig the
sphincter has much the same appearance as in man, whereas
in the horse it forms a wide but very flat band.

The dilating fibres of the iris present a very difficult sub-
ject of investigation.

And here I must express my belief—a belief the result of
repeated and very careful observations—that the fibres de-
scribed by Mr. Bowman as probably the contractile fibres of
the iris are in reality the outer cellular coats of the vessels.
The outer coat is very abundant in the vessels of the iris, and
indeed even in the blue eye towards the sphincter quite ob-
scures the bore of many of the vessels, and prevents the recog-
nition of their vascular character, which can only be deter-
mined by tracing them to their more external and more
obviously vascular truriks. The distribution of these vessels,
radiating between the sphincter and the circumference of the
iris, and forming in the region of the sphincter a close and
knotted plexus, corresponds accurately with Mr. Bowman’s
description of the distribution of the fibres of the iris. His
account of the tissue of these fibres, which he considers as
probably contractile, harmonises with the characters of the
cellular tissue that clothes the vessels. This is peculiar ; con-
sisting of very soft-looking fibres, whose fasciculi often require
the best aid of a first-rate glass to resolve them into their
constituent elements; destitute apparently of yellow elastic
fibres, as in the case of the cellular tissue of the uterus, but,
like this, containing abundance of free nuclei, of roundish or
elongated form. The fibres are completely gelatinised by
acetic acid. Now such a tissue can hardly, in the present
state of our knowledge, be regarded as contractile ; at any rate,
if we can find any ordinary muscular tissue to account for the
dilating action. On teasing out portions of the outer part of
the human iris, I have found long delicate fasciculi, whose
faint outline, absence of fibrous character, and possession of
well-marked elongated nuclei parallel to the direction of the

CONTRACTILE TISSUE OF THE IRIS. 15

fasciculus, left no doubt in my mind that they were plain
muscular tissue.

So far my observations regarding the dilator agree with
Kolliker’s, but whether or not these fasciculi are connected
with the cellular coat of the vessels I have hitherto been
unable to determine.

Among the lower animals the albino rabbit and guinea-pig
appeared but little suited for the elucidation of this point.
I have been most successful with the eyes of a horse, where,
from the thickness of the iris and the abundance of pigment (for
the eyes were black ones), I anticipated but little result from my
examination. Having removed the uveal pigment from behind,
I found that I was also able to strip off from the anterior sur-
face a tough membrane, a portion of which, put under the
microscope, appeared to be made up of peculiar short felt-like
fibres, which were gelatinised by acetic acid. At and near
the pupillary margin this membrane comes off in a continu-
ous layer, leaving a delicate reticular structure, which contains
the muscular tissue. It also contains vessels, as I proved by
injection, and a black network, which consists of fine fibres,
yellow, and highly refracting, more or less encrusted with pig-
ment. Jam uncertain whether or not this be a network of
divided nerve-tubes with adhering pigment; in some spots
the pigmental crust was absent from a considerable length of
the fibres. The sphincter pupille is beautifully seen as a
broad flat band, of extremely well-marked, unmixed, muscular
fibre-cells ; but crossing this at right angles are found, here
and there, other flat bands of fibre-cells, which are in so thin
a layer that without isolation the width of the individual cells
cannot be seen, and they are evidently of similar dimensions
to those of the sphincter. On addition of acetic acid their nuclei
are also seen to be exactly like those of the sphincter. These
‘bands divide in their course towards the pupil into several
fasciculi, some of which cross over the sphincter at right angles
till very near to its pupillary margin, and then seem to blend
with the sphincter by making a slight curve. Most of the
fasciculi, however, arch away earlier from their first course
and join the sphincter in more or less oblique lines. The
bands from which these fasciculi diverge may be traced away
from the pupil for some distance, continuing their course at
right angles to the sphincter till they are obscured by other
tissues. Hence I think the inference may fairly be drawn that
these are the insertions of the dilating muscular bundles. In
the horse, then, the dilating fasciculi appear to consist of pre-
cisely the same tissue as the sphincter, and to blend with it
in their insertion. The flat bands of muscular tissue above

16 CONTRACTILE TISSUE OF THE IRIS.

spoken of seemed to have no special relation to the vessels,
some of which were filled with injection. In the outer part
of the iris of the same horse I found a delicate muscular fasci-
culus lying near but not intimately connected with one of the
radiating vessels of this part. In the human iris I have seen
a muscular fasciculus, as it appeared from the nuclei it con-
tained, crossing the sphincter at right angles for a short dis-
tance ; this observation, so far as it goes, seems to imply that
the same mode of insertion of the dilator occurs in man as
in the horse.

The fibre-cells of the dilator appear to be held together
much more closely than those of the sphincter, at least in the
outer part of the iris; for I have never been able to define the
individual fibre-cells im a perfectly satisfactory manner in the
dilator, though I have often teased out portions of the outer part
of the iris. The dilating muscular tissue is also probably less
abundant than the muscular tissue of the sphincter ; and this,
if the fact, will help to account for the comparative difficulty
in discovering it. I may here mention that both in the cat and
in the rabbit, soon after death, dilatation of the pupils being
present, exposure of one iris to the air caused it to contract
at once, while the pupil continued dilated in the other eye,
which was untouched. Ido not know if this fact has been
observed before, but it is interesting in two ways—first, as
showing that the muscular tissue of the iris, like other mus-
cular tissue, is obedient to the stimulus of exposure; and,
second, as proving either that the sphincter is in these animals
a decidedly more powerful muscle than the dilator, which is
equally exposed to the stimulus ; or else that the fibres of these
two muscles have different endowments, as has been shown by
Mr. Wharton Jones to be the case with the muscular tissue of
the arteries and veins of the bat’s wing; where, although the
veins are muscular, and even contract rhythmically, yet the
arteries alone exhibit tonic contraction when irritated - me-
chanical stimulus.

As rich: network of extremely fine fibres, seen readily i in the
blue human irissvjewed from the anterior aspect, appears to
represent the nerves of the organ. The fibres are of a yellowish
colour, and are possessed of pretty high refractive power; they
present, if really nervous, a good illustration of the division
and anastomosis of ultimate nerve-fibres ; the smallest divi-
sions visible under a high power are seen only as fine lines.

I have not seen any nerves in the human iris presenting the
double contour ; but in the iris of a cat, so fresh that the tissue
contracted under the needles as I teased it out, the double
contour of the nerve-tubes was already very strongly marked,

OBJECTS FOR MICROSCOPICAL EXAMINATION. 17

showing the existence in this animal of the white substance
‘of Schwann in these nerves. The double contour surrounded
the ends of the nerve-fibres which I supposed to have been
broken by the teasing process. ‘This last fact seemed to con-
firm the general belief that the double contour is a post-
mortem effect, which, however, was in this instance a very
rapid one.

I believe that a further investigation of the fresh blue iris
in man, and of the horse’s iris, would supply the means of
finally settling the question of the distribution of the dilator
pupille.

My engagements do not allow me to carry the inquiry fur-
ther at present; and my apology for offering the results of an
incomplete investigation is, that a contribution tending, in
however small a degree, to extend our acquaintance with so
important an organ as the eye, or to verify observations that
may be thought doubtful, may probably be of interest to the
physiologist.

Hints on the Subject of collecting Objects for Microscopical
Examination. By Grorcr Suappo7t, Esq.

Havine procured a good microscope, it is often a source of per-
plexity to the novice to obtain a sufficient supply of objects on
which to exercise its powers, although the real difficulty consists
not in procuring enough, but in finding time to examine with
proper care all that is readily obtainable. It must be admitted
that the acquisitive powers, like all others, are materially im-
proved by being exercised, and many good collectors in embryo
remain undeveloped from the want of a little information to
commence upon. The object I have in view is to offer a few
hints to those who may happen to be deficient in this funda-
mental knowledge, especially as regards the means of finding
Diatomacez, Desmidiez, and other Alga. Masses of water
in all situations are generally to be examined for objects of this
class,

Rivers, brooks, springs, fountains, ponds, marshes, bogs,
and rocks by the sea side, are all localities that may be
expected to be productive, some being more prolific than
others, and the species obtained differing of course in general,
to a certain extent, according to the habitat.

On considering the nature of some of the places indicated
it will of course be apparent that in order to spend a day in

VOL, I. c

18 ‘HINTS ON COLLECTING OBJECTS FOR

collecting with any comfort, it will be necessary to make some

provision for keeping the feet dry, for which purpose a pair of

India rubber goloshes will answer, or better still a pair of

waterproof fishing boots, but without one or other the work is~
by no means pleasant.

A dozen or two of small bottles made of glass tubing about
half an inch in diameter and without necks, and from one to
two inches in length, are the most convenient depositories for
the specimens if intended ultimately for mounting ; and it is
advisable also to take two or three wide-mouthed bottles of a
larger size, holding from_ one to two fluid ounces, an old iron
spoon, a tin box, some pieces of linen or calico two or three
inches square, a piece of string, a slip or two of glass with the
edges ground, such as are used for mounting objects, and,
lastly, a good and pretty powerful hand magnifier. Two Cod-
dington lenses mounted in one frame of about balf an inch and
one-tenth of an inch in focal power are specially convenient.

Perhaps it will be as well in pointing out a few localities
to describe some that I have actually visited, with the means
of access, and the appearance of the various species en masse
that I have met with.

Swanscombe Salt Marsh will be found well worth a visit, and
it can be reached either by steamboat or railway from London
Bridge to Northfleet. On quitting the railway station make
towards the almshouses on the top of the hill, and arriving
at the road turn to the left, descend the hill and cross a sort
of bridge over a somewhat insignificant stream. Continue
along the main road a little further until a point where it
begins to ascend again, and diverges to the left towards the
railway, here quit it, taking your course along an obscure
road nearly in a direct line with the main one, passing
a windmill on the right hand, and continuing until you arrive
at another still more obscure road turning off to the right,
which road appears as if made of the mud dredged from the
bottom of the river and partially hardened. This is Swans-
combe Salt Marsh, and the road just described leads towards
Broad Ness beacon. On either side is a sort of ditch, one
containing salt or very brackish water, the other filled with a
sort of black mud, about the consistence of cream, the surface
being in parts of a slaty grey with little patches here and
there of a most brilliant brown colour glistening in the sun-
shine, and presenting a striking contrast to the more sombre
shade. By carefully insinuating the end of one of the slips
of glass under this brilliant brown substance and raising it
gently, it can be examined with the Coddington, and it will
probably be found to consist of myriads of specimens of

S| i ai

MICROSCOPICAL EXAMINATION. ; 19

Pleurosigma (Navicula of Ehrenberg) angulatum, or Balti-
cum, or some other species of this genus. The iron spoon
now is useful, as by its aid the brown stratum, with little or
no mud, can be skimmed off and bottled for future examina-
tion. On the surface of the water in the other ditch may be
noticed a floating mass of a dark olive colour, which to the
touch feels not unlike a lump of the curd of milk, and consists
of Cyclotella Menighiniana and a Surirella or two embedded
in a mass of Spirulina Hutchinsia, and another mass of floating
weed which feels harsh to the touch, proceeding from a quantity
of a Synedra, closely investing a filamentous alga, and else-
where Meloseira nummuloides ( Gallionella of Ehrenberg),

Ina trench by the sea-wall, as itis termed, isa mass of brown
matter of a shade somewhat different to any hitherto observed,
adhering to some of the parts of the trench, being partially sub-
merged, and having a somewhat tremulous motion on agitating
the water. This is a species of Schizonema, and it consists of
a quantity of gelatinous hollow filaments filled with an im-
mense number of bright brown shuttle-shaped bodies, like
very minute Navicule. It is not necessary to be particular
about collecting the specimen free from mud, as the filaments
are so tough that the mud can be readily washed away by
shaking the whole violently i in a bottle of water and pouring
off the mud without at all i injuring the specimen. The Am-
phisporium alatum communicates a somewhat frothy appearance
to the otherwise clear water, and to get any quantity of this
requires a little management, but by skimming the surface
with the spoon, and using one of the larger bottles, an abund-
ance may readily be obtained.

Between the sea-wall and the river the marsh is intersected
in every direction with a number of meandering creeks, being
in some places eight to ten feet deep, though in others quite
shallow, but it is exceedingly difficult to make one’s way
amongst them, and I have never found them so prolific any-
where, on the few occasions of my visiting the place, as in the
parts more away from the influence of the ‘tide. It will be ob-
served, from what I have stated, that the brilliant brown colour—
of a deep but bright cinnamon tint—is one of the best indica-
tions of the presence of Diatomacee ; and, though this is by no
means universal, the variation is most frequently dependent
upon the presence of something which qualifies the tint. The
peculiarity of the colour is due to the endochrome contained in
the frustule, and this must be in general got rid of before the
beautiful and delicate markings can be made out; but it is
highly advantageous and instructive to view them in a living
state, and this should be done as soon as possible after reaching

cQ

20 HINTS ON COLLECTING OBJECTS FOR

home with all specimens procured from salt-water localities,
as they rapidly putrefy in confinement, and emit a most dis-
gusting odour, not unlike that arising from a box of inferior
Congreve matches.

Washing in fresh water, and then immersing in creosote
water, preserves many of the species in a very natural-looking
manner ; but they are killed by the fresh water, and the en-
dochrome becomes much condensed, in the Pleurosigmata and
some other species. The addition of spirit quite spoils the
appearance of the frustules, as it dissolves the endochrome.

There is another salt marsh a little farther down the same line
of railway at Higham, which it would be well to explore ; but
as I have only paid it one visit, at the most unfavourable time
of the year I could possibly have hit upon—the early part of
December, I did not find many species there. I would observe
that, as far as my limited experience extends, the most favour-
able months for procuring Diatomacee are April, May, Sep-
tember, and October, but some species are found in perfection
as early as February, and many as late as November, and a
few at all times of the year.

There is a piece of boggy ground near Keston, beyond
Bromley in Kent, where the river Ravensbourne takes its rise,
where many interesting species of Desmidiez and other fresh-
water alge may be procured.* From Bromley walk on
towards Keston, passing near Hayes Common and Bromley
Common on the right. Continue for about another half mile
along the road, and then turn to the right hand, pass the reser-
voirs, and approach an open space where there is a bog of
about a quarter of a mile in extent, and, tending towards the
right, make your way amongst heaths, ferns, mosses, and the
beautiful Drosera rotundifolia (sundew), to the lower part
of the little stream rippling through a sort of narrow trench in
the Sphagnum, &c. By working your way up the stream
you ayoid the inconvenience, which would otherwise be expe-
rienced, of the water being rendered turbid in consequence of
having to tread in the boggy ground.

In the centre of the little stream may be observed something
of a pale pea-green colour flickering about in .the current,
which, on your attempting to grasp, most likely eludes you, and
slips through the fingers, from being of a gelatinous nature. It
consists of a hyaline substance, with a comparatively small quan-
tity of a bright green endochrome disposed in little branches,
and this is the Draparnaldia glomerata. Another object is a

* An omnibus leaves the Elephant and Castle at ha'f-past nine every
morning for Bromley, which is the most convenient means of access to the
spot.

MICROSCOPICAL EXAMINATION. 21

mass of green filaments, rather harsh to the touch, very slip-
pery; when viewed with alens of moderate power each filament
is seen to be surrounded with several bands of green dots, look-
ing like a ribbon twisted spirally, and may be recognised as
Zygnema nitidum. In various parts there are other species of
Zygnema, Tyndaridea, Mougeotia, Mesocarpus.and many others.
Keeping up the stream, and occasionally diverging a little
on either side of it amongst the miniature bays and pools
in the Sphagnum, on looking straight down into the water
we shall probably see at the bottom a little mass of jelly, of a
bright green, and studded with numerous brilliant bubbles of
oxygen gas. This is the general appearance of most of the
Desmidiex, as Micrasterias, Euastrum, Closterium, Cosma-
rium, &c. &c. The spoon is also a handy tool in this case,
though by practice the finger will do nearly as weli, the chief
difficulty arising when the specimen is brought to the surface
of the water, it not being easy to get it out in either case with-
out losing a considerable portion of it,

Little pools in the bog, made by the footsteps of cattle, are
particularly good spots to find Desmidiez, and [ have fre-
quently found many species in a very contracted space.

The most prolific bog I am acquainted with is at Tunbridge
Wells, near a house Laws as Fisher’s Castle, not far a
Hurst Wood. There is also a good one at Bae at a spot
called West End.

It must not be imagined that nothing can be obtained in
this department of botany without going some distance from
town, but assuredly only commoner and fewer species can be
met with nearer home. At the West India Docks I have
found Synedra fasciculata, Gomphonema curvatum, Diatoma
elongatum, Diatoma vulgare, Surirella ovata, &c. &c. ; and, by
the way, at this same place a few objects not of the botanical
class, as Spongilla fluviatilis, Cordylophora lacustris, Aleyo-
nella stagnorum, &c., are obtainable in abundance in the
autumn,

In the Serpentine may be found Cladophora glomerata and
Spheroplea crispa, two of the filamentous alge ; and in the
ornamental water in St. James’s Park, Cocconema lunceolatum,
and other species of this genus, Gomphonema_ cristatum,
&e. &c. Epping Forest, about the neighbourhood of Leyton-
stone, Snaresbrook, Wanstead, and Woodford Bridge, are also

capital localities for the filamentous Algee, especially the last
named, where Witella translucens and Chara vulgaris abound.

Inthe fountains in the Surrey Zoological Gardens I have
met with several species of Diatomacee and Desmidiez at dif-
ferent seasons, including the genera of Synedra, Gomphonema,

22 OBJECTS FOR MICROSCOPICAL EXAMINATION.

Cocconeis, Stauroneis. Cymatopleura, Surirella, Pleurosigma,
&c., among the former, and Closteriuwm, Cosmarium, and
Staurastrum among the latter.

Hampstead Heath, although producing some of the above,
is a place far more prolific in aquatic animalcules, even if we
exclude the Volvox globator froin this latter class, and reckon
it as belonging to the vegetable kingdom.

Observations on the existence of CELLULOSE in the Tunie of
Ascidians. By T. H. Huxtey, Esq., F.R.S.

A CAREFUL examination of a number of species of the Ascidian
genera Boltenia, Cynthia, Molgula,.Phallusia, Syntethys, Apl-
dium, Pyrosoma, and Salpa—including, therefore, every mo-
dification of the type, has led me to the following conclusions
with regard to the structure of the mantle. The investigation
was made with a full knowledge of what had been done by
Léwig and Kolliker and by Schacht (p. 34), and I have only
ventured to differ from them upon strong evidence.

1. In the most gelatinous forms of the test, as in Syntethys
and Salpa, it consists of a soft homogeneous or delicatel
Striated basis, through which round nucleated cells (nuclei of
Kélliker and Lowig) are scattered. These cells present no
ramifications, and the presence of cellulose is demonstrated
with very considerable difficulty. When the iodine solution is
added the whole mass becomes coloured yellowish-brown, the
nucleated cells taking rather a deeper tint than the rest. The
addition of sulphuric acid slightly contracts the whole sub-
stance, and if used with care gives the edges the characteristic
blue tinge. The cellulose is evidently diffused through the
intercellular nitrogenous basis ; for the first evidence of the
operation of the sulphuric acid is seen ina slight diffused, even
green shade, which is produced by the incipient blue re-action
of the cellulose mingling with the existing yellow-brown colour.
As the action of the test goes on, the edges of the membrane
become deep blue, while the green tinge passes insensibly into
the blue on the one side and into the yellow on the other.

As Schacht justly points out then, the substance of the test
is not pure cellulose but cellulose deposited in a nitrogenous
membrane. It exists in the same condition as the calcareous
salts in bone, or as the chondrin in cartilage.

Substituting cellulose for calcareous salts, the structure of
the test of Salpa is exactly that of the bone of plagiostomous
fishes (Leydig, Beitrage zur Anat. d. Rochen, Haie, 1852).

HUXLEY ON CELLULOSE IN THE TUNIC OF ASCIDIANS. 23

2. Pyrosoma has a firmer test, which contains far more
cellulose. This is more readily detected by the iodine and
sulphuric acid, but in its relation to a general nitrogenous
basis precisely resembles that of Salpa.

The uucleated cells differ from those of Salpa in being
thrown into very long processes which meet and unite—just
like those of Volvox as described by Mr. Busk. On the other
hand they assume exactly the appearance of bone corpuscles—
though the processes are generally straighter and are rarely
branched.

Making the same substitution as before, we have in the test
of Pyrosoma a structure comparable to that of the lamina
papyracea of the ethmoid bone.

3. In the Phallusie there is an indistinctly fibrillated basis,
containing a large amount of cellulose in all essential respects
resembling the foregoing. Nucleated cells, provided with
irregular processes, are scattered through this substance.

The large cells described by Léwig and Ko6lliker and by
Schacht are not cells at all but are vacuola—very probably
produced, like the cancelli of ordinary bone, by interstitial
absorption. There is no lining membrane like that described
by Schacht. With care the walls may be coloured deep blue
to their very edges. The appearance of fibres is produced by
the striation which runs through the whole mass, and is
especially distinct upon the walls of the cavities. It exists
after the action both of sulphuric acid and of caustic soda.

Lastly, the resemblance to perfect bone is completed by the
canals which are hollowed out in the substance of the test for
the vessels (or rather prolongations of the outer tunic, which
is what they really are). In the walls of these canals I have
frequently seen the nucleated cells projecting just as Kolliker
describes them in the “ medullary canals”? of developing bone
(Mikroskopische Anatomie, p. 369).

The spiral fibres described by Schacht are the muscular
fibres surrounding the wider portions of the vessel-like pro-
longations.

Finally, with regard to the relations of the cells to the cellu-
lose—anatomically and physiologically—I do not see any force
in the distinction attempted to be established by Schacht
between animals and plants. The nucleated cell of the As-
cidian tunic answers exactly to the primordial substance of the
plant. The cellulose is deposited outside both. The amount
of nitrogenous matter mixed up with the cellulose deposit
appears to be a mere question of degree—and the nature
and existence of an intercellular substance in the vegetable

24 HUXLEY ON CELLULOSE IN THE TUNIC OF ASCIDIANS.

kingdom are still matters too much disputed to be good grounds
of distinction.

The physiological theory of Léwig and Kdlliker, that the
cellulose of the Ascidians is derived from the Diatomacee
upon which they feed—is incompatible with the fact (Annals
of Nat. Hist, Aug., 1852) that the larval Ascidian contains
cellulose before any of its organs are developed.

To examine the test of an Ascidian for cellulose, I find the
best way to be, to take a very thin section and moisten it with
a strong solution of iodine in iodide of potassium. After being
thoroughly impregnated with the iodine, the superfluous fluid
should be drained off, and the segment carefully blotted with the
finger [or hair pencil]. A handkerchief or blotting-paper may
readily give rise to error by leaving behind small fragments of
vegetable fibre. A drop of sulphuric acid, as strong as can be
procured, should now be added. If much cellulose is present a
deep blue colour will appear immediately, beginning at the edges
of the slice ; if there be but little, the colour will not appear for
some time. The application of the test requires some care ;
and while its success is most valuable evidence of the presence
of cellulose, its failure is not by any means negatively con-
clusive, unless the experiment has been frequently and care-
fully repeated.

( 25)

TRANSLATIONS.

Description of Actinorurys Sor. By A. Korirker. From
Siebold and Kélliker’s Zeitsch., 1. p. 198. 1849.

Tue simplest forms in animated nature are to the genuine
naturalist of great value and significance. Though wanting
in the attractions derived from multiplicity of shapes, and
although the investigation of their life is apparently without
any immediate purpose of utility, yet do they hold out to the
true philosophic inquirer an ample reward, and, from the
paucity of means exhibited in them for the production of great
effects, they are well calculated to charm and interest the mind.
The solution in fact of general questions of the utmost im-
portance depends upon a correct knowledge of the lowest
organisms—such questions, for instance, as—What is an
animal? What a plant? What an organism? or even, What is
life itself? And when it is considered that these lowest
forms are in great measure to be regarded as simple cells, an
unprejudiced inquiry into the vital phenomena presented in
them, becomes of daily greater importance towards a proper
comprehension of the higher organisms, which are also in great
part composed of cells.

Induced by these considerations, the author has pursued the
investigation of certain of the lower forms of animal life.
Some of the fruits of his labours have already appeared in a
paper on the Gregarine, &c., and he now presents the follow-
ing account of the Sun Animalcule— Actinophrys Sol.

I. Anatomy of Actinophrys Sol.—The form of the Actino-
phrys (figs. 1, 2, 3) is that of a depressed sphere ; viewed on the
flat sides, it is perfectly circular, and on the edge, elliptical. The
surface of the body is universally and pretty closely beset with
delicate tentacular filaments. The length of these filaments is
at least equal to, or much greater than, the longer diameter of
the animalcule ; they arise from a rather wide base, and be-
coming gradually attenuated, though with frequent nodosities,
terminate in an extremely fine almost invisible point.

The colour of the animalcule, independent of all foreign
contents, is, to the naked eye, a dull white; when more
closely examined, the interior usually appears whiter than,
and to be rather sharply defined from, the transparent external
portion ; and this is confirmed upon microscopic inspection.

Measurements: the smallest individual that came under
the author’s inspection measured 1-38th—1-30th"’; the largest

26 KOLLIKER ON ACTINOPHRYS SOL.

1-6th—1-4th’’; the medium size was 1-8th—1-6th’”; the
filaments 1-6th—1-3rd’”, or even 4” long, and 0+0016—
0 0006'” wide at the basis; the little nodosities upon them
0-007” long, and 0-004’”" wide.

The structure of Actinophrys has not hitherto been correctly
understood by the greater number of observers. According to
Ehrenberg (‘ Infusor.,’ p. 303), it possesses a mouth with a pro-
boscis and an anus, which are opposite to each ether, and in
the interior, numerous stomachs, on which account it is referred
to the division Enantiotreta of the Enterodela or Polygastrica
having an intestine. The older observers also, such as O, F,
Miiller and Eichhorn, are, to some extent, of the same opinion,
as well as most modern zoologists, who simply adopt the
statements of Ehrenberg. But Dujardin (‘ Infusoires,’ p. 259)
characterises Actinophrys as * animaux sans _ organisation
appréciable ;’ adding, in explanation (p. 260), that their body
consists of a soft grumous substance, in which nothing can be
observed but variously sized granules, and frequently very large
vacuole. According to the author’s investigations, Dujardin,
in this instance, as in many others in which he has combated
the views of Ehrenberg, is altogether in the right ; for, although
he was not acquainted with the vital phenomena of Actinophrys,
he comes very near the truth in what he has observed of its
structure.

Actinophrys, in fact, does not present a trace of mouth,
stomach, intestine, and anus, consisting entirely of a perfectly
homogeneous substance, of very soft and delicate consistence.
Examined under a higher magnifying power (Plate I. figs. 1, 2,
3) the whole animalcule at first sight seems to be composed of
the most regular and delicate tissue of round or polygonal cells ;
but on closer inspection it will soon be found that, in the usual
sense of the term, there are not in reality any cells. On the
contrary, it will be seen that what appears as a cell-membrane
is not any special envelope, but that it is in continuous con-
nexion with a pale substance, which in greater or less quantity
occupies, like a sort of intercellular substance, the space
between the supposed cellular cavities; and also that the
numerous opaque granules are retained in this substance, and
in no case contained im the cavities, which are filled merely
with a clear aqueous fluid (figs. 1, 4),

When the animalcule is torn or crushed it becomes evident
that it is entirely composed simply of a homogeneous substance
with vacuoles, for it will be found that the supposed cells may,
at pleasure, under pressure, be made either to coalesce into
larger or be divided into smaller cavities, presenting in all
respects the character of the normal ones. The only thing

’ KOLLIKER ON ACTINOPHRYS SOL. 27

indicating the existence of cells is this, that in the innermost
portions of the animal after it has been crushed, a few vesi-
cular particles come into view, which, owing to the pre-
sence of an internal corpusule, more resemble cells. Under
pressure these vesicular bodies may be readily isolated, they
then behave sometimes as cells with nucleus and nucleolus,
sometimes as free nuclei. The author is in fact inclined to
regard them as cells and nuclei, lying in some of the interior
vacuoles, for such, and such only, are the vesicular spaces in
which they are inclosed, and will say more about their nature
subsequently.

Disregarding, then, these adventitious elements of secondary
importance, the entire Actinophrys is throughout composed of
a simple homogeneous substance, with granules and vacuoles.
In it may more or less clearly be distinguished two portions,
a cortical and a nuclear. The former (figs. 1, 2, 3, a) is, on
the average, 1-36th’”’ thick, surrounds the nucleus, supports
the tentacular filaments, and is more transparent than the
nuclear (figs. 1, 2, 3, 6), which presents the appearance of a
flattened sphere of more or less’ white colour. Both portions
possess essentially the same structure, and the difference between
them depends upon the circumstance that, in the substance of
the nucleus, there are many more granules than in the cortical
portion. These granules are rounded, opaque, very minute
(at most 0- 0005” or 0:001’’), insoluble in acids or alkalis, and
therefore probably of a fatty nature. The homogeneous sub-
stance of the body (figs. 1, 2, 3, 4, c), of a yellowish tint, is
very soft, but highly elastic, so that an Actinophrys placed on
a plate of glass in too stalls quantity of water, becomes flat-
tened out into a large and extremely thin ie which, upon
the addition of water, reassumes its original globular form ; it
is rendered pale by acetic acid and cold potass, in which latter
it gradually, but when heated, rapidly, dissolves, and it is
therefore of a nitrogenous nature. ‘The clear spaces or vacuoles
(figs. 1, 2, 3, 4, d) are of pretty uniform size, 0 009—O 02’,
or in the mean 0 012” in diameter. In the cortical portion
they are disposed in two or three tolerably regular layers; but
in the nuclear part, and especially towards the centre, they
exhibit no definite arrangement, and are at the same time
smaller and have more interstitial substance than in the cortical
portion, where there is frequently only a thin lamella between
two vacuoles. The peripheral layer of this fundamental sub-
stance is somewhat thicker, although still extremely thin, even
where the tentacular filaments are given off from thicker parts
of it. These filaments are in fact immediate prolongations
from it; they (figs. 1, 2, 3, 4, e) consist of the same sub-

28 KOLLIKER ON ACTINOPHRYS SOL.

stance as the rest of the body, from which they differ only
in their never having vacuoles, and if granules, but very few of
them.

I. Physiology.— —As regards the vegetative functions, the
mode in which the Actinophrys is nourished is of the highest
and most special interest. Although the creature has neither
mouth nor stomach, yet it takes in solid nutriment and rejects
what is indigestible. This miracle, for so it may almost be
called, is thus effected: the Actinophrys feeds upon infusoria
of all kinds—minute crustaceans (Rotifera, minute species of
Lynceus, the young of Cyclops, &c.), and the lower alge
(Diatomacez, spores of Vaucheria, Closterium, &c.). When,
in «its progress through the water, it approaches one of these
little plants, or when an Infusorium has come into proximity
with it, both plant and animal, as soon as they touch one of the
tentacular filaments, usually adheres to it. Now as the fila-
ment with its prey slowly shortens itself, and the latter ap-
proaches the surface of the body, all the surrounding filaments
apply themselves upon it, bending their points together so that
the captive becomes gradually enclosed on all sides (fig. 2, f) ;
according to all appearance these filaments also become more
or less shortened. In this way the morsel is gradually brought
to the surface of the body, the filament by which it was seized
being finally so much shortened as to disappear altogether, and
having, as not unfrequently happens, relinquished its hold
upon the prey, after the latter has become encompassed by the
surrounding filaments. These gradually apply themselves
more and more closely together around it, forcing it towards
the surface of the body.

The following proceeding now takes place:—The spot of
the surface, upon which the captured animalcule is lying,
slowly retracts and forms at first a shallow depression gradu-
ally becoming deeper and deeper (fig. 2 f), in which the
prey, apparently adherent to the surface and following it in
its retraction, is finally lodged. The depression, by the con-
tinued retraction of the substance, now becomes deeper; the
imprisoned animalcule, which, up to this time, had projected
from the surface of the Actinophrys, disappears “entirely within
it; and at the same time the tentacles, which had remained
with their extremities applied to each other, again erect them-
selves and stretch out as before (fig. 2 9). Finally, the de-
pression acquires a flask-like form by the drawing in of its
margin (fig. 2g), the edges of which coalesce, and thus a
cavity closed on all side, is formed, in which, the prey is
lodged. In this situation it remains for a longer or shorter
time, gradually however approaching the central or nuclear

KOLLIKER ON ACTINOPHRYS SOL. 29

portion, and at last passing entirely into it in order to await
its final destination. In the meanwhile the external portion
of the Actinophrys regains in all respects its pristine condition.
The engulphed morsel is gradually digested and dissolved, as
is readily seen by its change of appearance from time to time.
If entirely soluble, as, for instance, an infusorium, the space in
which it is contained contracts as the dissolution of its con-
tents goes on, and finally disappears altogether ; should there
be, however, an indigestible residue (a membrane composed of
cellulose, a portion of chitine, a shell of a Lynceus, or case of
a Rotifer, &c.), a passage for its exit is formed, and it is ex-
pelled by renewed contractions of the homogeneous substance,
and in the same direction or nearly so as that which the morsel
followed in its introduction. The passage and the opening
through which the expulsion was effected disappears again
without leaving a trace.

The above is a representation in general terms of the very
curious mode in which the Actinophrys receives, digests, and
rejects what remains of its nourishment. The following ob-
servations may serve to make it better understood. As regards
the formation of the tentacular filaments it is stated by Ehren-
berg, who at the same time assigns to them the duty of seizing
the prey, that they exert a “rapidly fatal”. influence upon the
captured animalcule. This is incorrect. The author has very
often seen infusoria which were adhering to the tentacles still
in motion, and even when arrived near the surface of the body
break away and escape ; and in several cases he has observed
very lively movements in animalcules which had been com-
pletely swallowed and imbedded in the cortical substance or
in the nucleus. It would appear that the only action of the
tentacles is to retain the prey by their adhesive surface, and
probably to involve it also with their extremely fine extremities,
and then that, by their mutual approximation, they continue
to hold it fast, and at the same time by their contraction bring
it towards the surface of the body.

In the second place, with respect to the non-existence of a
mouth, stomach, and anus, no doubt whatever can be enter-
tained. Without the slightest notion of the remarkable con-
ditions he was about to find, the author approached the investi-
gation of Actinophrys with a due belief, at least, in the existence
of the mouth and anus, described by Ehrenberg. When he
for the first time witnessed the process of reception ofa morsel,
he thought in fact that he had found the mouth in the depres-
sion formed on the external surface ; and in the whitish nucleus
into which the morsel was finally lodged, a large central
stomach. But he was soon undeceived, for, by longer observa-

30 KOLLIKER ON ACTINOPHRYS SOL.

tion of one and the same individual contained in a watchglass
he soon perceived that the supposed mouth disappeared again
after the entrance of the morsel without leaving a vestige,
whilst other observations showed him that the supposed
stomach was a homogeneous substance, with similar cayi-
ties, and of the same nature as the cortical. Now as he had
also ascertained the merely transitory existence of the anus,
and, by steadfast consideration for hours together of different
individuals, had also made the discovery that the Actinophrys
employs the same part of the surface of its body at pleasure
and temporarily as either mouth or anus—the mystery was
cleared away, and views opened out which further investigation
the more firmly established.

In the reception and rejection of the morsel, the manifestly
contractile homogeneous substance of the body appeared to
play the principal part. By its retraction in any part a
hollow is formed into which the morsel enters; then the
borders of the hollow approach and coalesce in consequence of
contraction, and the morsel is within the body; new con-
tractions, lastly, propel it from without imwards towards the
nucleus, and at a later period serve again to expel the undi-
gested remains. All these contractions are partial, taking
place only in one or few spots at the same time, whilst at
other places the substance of the body remains passive, yielding
before the advance of the morsel. How the clear spaces are
concerned in the penetration, advance, and expulsion of the
food, it is difficult to see; they seem to disappear in places
and to be reformed, though it cannot be altogether denied that
they may merely separate from each other in order to make
way for the entrance of the foreign body. It is especially
to be remarked that the advance of the morsel into the body
has the greatest resemblance with what is observed in uni-
cellular infusoria, having a mouth, such as Bursaria, &c., when
the morsel enters the soft contents of the cell, or the so-called
parenchyma.

The number, as well as the size of the morsels, taken at one
time by the Actinophrys, is very various. Very frequently
there may be 2, 4, 6, at the same time—frequently also more
than 10 or 12. Ehrenberg counted as many as 16 stomachs,
which may be looked upon as so many separate morsels. He
also noticed the ingestion of indigo, which could not have
gained admission in any other way than that by which the
infusoria and other aliment enter, The largest morsels noticed
by the author consisted of a Lynceus or a young Cyclops.
Eichhorn indeed mentions even a water-flea (Daphnia ?), about
the size of which, however, no remark is made.

KOLLIKER ON ACTINOPHRYS SOL. 51

The mode in which the nutrient morsel is digested is not
clear. Every morsel, without exception, lies in a large vacuole,
formed temporarily for its reception in a small quantity of
clear fluid, of which it does not appear whether it comes from
without, or is secreted in the interior of the animal and col-
lected round the morsel. The food is digested in a few hours
(2—6), and the indigested residue, together with the drop of
fluid by which it is surrounded, is expelled. In this way the
sharply defined drop, with the enclosed faces, are pushed in
an entire mass through the parenchyma of the body. Scarcely
arrived at the surface, however, the mass breaks up and _ be-
comes dispersed, although the solid particles which had been
included not unfrequently remain for some time as a granular
body with irregular outline, as a greyish cloud, in the neigh-
bourhood of the animal, until it is at last entirely dissipated.

Of the other vegetative phenomena there is not much to
remark. Regarding the mode of growth, of the conditions
attending which there is nothing to be seen, it might merely
be remarked that individuals which have not eaten for some
time present only a few granules in their parenchyma, and have
a nuclear substance almost as transparent as the cortical ;
whilst, on the other hand, those containing numerous morsels
of food, and consequently which are evidently better nourished,
invariably present numerous granules. Hence it might with
tolerable certainty be concluded that these (fat) granules are
formed from the food, and during fasting are re-absorbed ;
probably, in general, they are constantly formed and removed
as must in some degree be assumed to be the case with the fat
of the higher animals.

In the Animal Sphere, the movements are especially de-
serving of all consideration. As the lowest animals in general,
so does Actinophrys move entirely without the intervention
of muscles or nerves; but besides this, it presents the pe-
culiarity that the whole parenchyma of its body in all its
parts, including the tentacular filaments, is contractile. All
the motions of Actinophrys are performed with the utmost
slowness, so slowly, in fact, that it is only by prolonged atten-
tion to one point, and still longer to the whole form, that it
can be perceived. In the first place are to be mentioned the
tentacular filaments, in which numerous changes of form, such
as elongation, shortening, local swelling, bending, &c., may
most readily be observed, whilst at the same time with them
the scattered granules in their substance move here and there,
although even in this case the utmost slowness is the rule; a
quick movement is never seen. It is especially interesting to
observe that the filaments, singly or together, frequently dis-

32 KOLLIKER ON ACTINOPHRYS SOL.

appear entirely, entering at last, as it were by continued re-
traction, into the substance of the body, and leaving no trace
of their former existence; and that they reappear with the
greatest readiness and with tolerable rapidity (figs. 3,4). This
disappearance and reproduction must be regarded in the same
light as the similar phenomena in Ame@ba, in which the processes,
as is well known, are of a very ephemeral nature ; the author
has frequently observed the phenomenon, and particularly in
the reproduction of the filaments, very clearly seen, how the
homogeneous substance forming the periphery of the body was
first elevated into minute warty eminences (fig. 4), which soon
become papillary (the ‘proboscis’ of Ehrenberg is probably
nothing more than one of such papilla), then conical, and
are finally produced into a long filament. Whether the fila-
ments which disappear are always reproduced in the same spot
is not determined; in some instances this did not appear to
be the case, although in every instance the number and posi-
tion of the filaments is pretty constant. Actinophrys, not
merely in the form of its processes, and their slow movements,
but also in this respect, differing altogether from Amwba.

In the rest of the body itself, movements are well and
clearly perceptible only in the reception and expulsion of the
food and its remains. Otherwise only the most faint indica-
tions of contraction are apparent in it, such as a slight undula-
tion of the border and inconsiderable quivering motions here
and there. 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 the author con-
sequently is altogether ignorant as to how locomotion of the
animal is effected. -That it is active in this respect appears to
be indubitable, for it was found, for instance, that when a
vessel with several individuals of Actimophrys was emptied
into a flat glass capsule, they were all at first scattered about at
the bottom, but subsequently, after about twelve to twenty-four
hours, were all floating at the surface, and indeed at the side of
the capsule. Ehrenberg and Eichhorn assert that the ascension
in the water of Actinophrys is effected by the taking in, and
their descent by the giving out, of air. But this is certainly
not the case, for whence could they obtain this air? Can it
be said that they secrete it within themselves like fishes? In
that case it must be visible. It appears to the author more
natural that the rising and sinking should be effected by alter-
nate contractions and expansions of the whole body. Other
motions can affect both the filaments and the body, but in
any case only through the slowest possible contractions.

KOLLIKER ON ACTINOPHRYS SOL. 33

Pulsating spaces, of which Siebold* describes two, imme-
diately under the integument in Actinophrys, were never seen
by the author, in as far as Siebold means such spaces as ap-
pear and disappear. If, on the other hand, he means only
expansions and contractions of the substance bounding the
vacuoles, but not such as to cause their disappearance, I
entirely agree with him, and have seen, as is stated above, not
two such only, but several.

Sensation also must certainly be assumed to exist in Actino-
phrys, only in it, as in the lower animals generally under this
term, nothing like the conscious sensibility of man is to be
understood ; but rather, if a comparison must be drawn, may
it be considered to resemble the condition present in the
spinal chord and in ganglions, when reflex excitement in them
is produced through nerves of sense.

Actinophrys perceives mechanical influences, and reacts
upon them by movements. This is proved by what takes
place when animalcules, &c., remain affixed to its tentacles,
and moreover by the circumstance that when the water in
which it is contained is carelessly agitated, every Actinophrys
contracts its tentacles, and even makes them disappear alto-
gether, and, indeed, with greater speed than is otherwise per-
ceived in these creatures, and when all is quiet they are again
protruded. These filaments consequently may just as well be
called tactile as prehensile ; or it may more generally be said
that the substance of the body is both contractile and sen-
sitive,

Under the head of the Reproduction of Actinophrys, the
author’s observations are extremely defective. Eichhorn and
Ehrenberg would seem to have observed spontaneous fission,
but it;is not said whether these observers concluded that this
takes place only from the occurrence of individuals apparently
partially divided, or whether they have actually witnessed the
production of two individuals from one. This is much to be
regretted, since, as will be apparent, partially divided indi-
viduals of Actinophrys by no means demonstrate the existence
of fission in this case. The author saw what follows :—Upon
persevering inspection of a biscuit-shaped individual in which
from analogy he expected to see nothing but that it was soon
about to undergo division, he was not a little astonished to
see it gradually assume an oval form, and finally to become a
single individual. At first he placed no importance on this
observation, and thought merely that his inquiry on the sub-
ject of reproduction had miscarried, but as he soon afterwards
again noticed the same thing in a second individual, the matter
appeared too remarkable to be passed over. He adverted to

* Verg. Anat., pp. 20, 22.

VOR; 1. D

34 KOLLIKER ON ACTINOPHRYS SOL.

the conjugation of the lower alge, and devoted himself
specially to the investigation of this point. ;

After some time thus engaged, he succeeded in one case in
observing through all the stages of the process ‘the complete
fusion into a solitary larger animal, of two individuals, origin-
ally perfectly distinct.” The resultant individual was im no
respect different from other single individuals, and it presented
no trace whatever of its having been formed out of two. He
was now very anxious to know what would become of it, and
actually observed it for a whole day without noticing anything
peculiar with respect to it. He then lost it by accident, and
was otherwise, also, unable, as he was obliged to discontinue
his observations, to follow the thing further; and he has been
obliged to leave the question undetermined whether or no the
fusion of two animals into one has anything to do with their
propagation. Of other facts connected with this subject, it
may be mentioned that the smallest individuals measured only
0-01'”"—0-02"", and presented very inconspicuous and few
vacuoles, and secondly, that, perhaps, the above-described gra-
nular and vesicular corpuscles within the nuclear portion of the
body might be germs just beginning to be evolved. Whether
this is the case, must be left to future observation to decide ;
but so much must be remarked, that multiplication by means of
germs generated in the interior indubitably occurs in certain
Infusoria ; the author has noticed in Euglena 4—6 embryos
in one individual, and entirely filling it, which at last, furnished
with their red point and cilia, broke through their parent,
leaving it an empty. case.

[To be continued. ]

On the Microscopical and Chemical Examination of the Mantle
of certain Ascipians. By Dr. H. Scwacut. Miiller’s
Archiv. 1851. p. 176.

Ir is known that a substance having the chemical relations of
cellulose was first shown by C. Schmidt (Zur vergleichenden
Anatomie der wirbellosen Thiere, 1845, p. 61) to exist in the
mantle of certain Ascidians ; and the fact was confirmed by
the chemical and microscopical researches of Kélliker and
Liwig (Ann. d. Sc. Nat., 1846, p. 193), who extended their
valuable observations over a great number of genera and species,
Both Schmidt, Kolliker and Léwig proved the existence
of the cellulose only by chemical analysis, but not by the
application of re-agents under the microscope; they found in
the mantle of the Ascidians a substance not affected either by

SCHACHT ON THE MANTLE OF CERTAIN ASCIDIANS. 35

hydrochloric acid, or by caustic potass, and which, after this
treatment, being heated with potass, gave out no ammonia, and
was consequently free from nitrogen,

According to the latter observers the substance consisted—

In Phallusia mamillaris: In Cynthia papillata :

Of Carbon . ee VASSAO! US . : 3 ASO
Hydrogen : BO Cstee oe HS : J 6°16
Oxvden. ig +,» -.01332,... Se seehndisss, OO
According to Schmidt, in Phallusia, 100 parts contained—
Carbon . ; . - 45°38
Hydrogen ee aes ees 6°47

The microscopic examination was made by Kolliker and
Léwig, both before and after treatment of the mantle with
hydrochloric acid. The form, and, for the most part also, the
external condition of the mantle remained almost unchanged
under this treatment, except that in Cynthia, the exterior
coriaceous layer became smoother and more flexible. Accord-
ing to them, but in opposition to Schmidt’s supposition, the
Polypes aad. Medusz contain no cellulose.

The methods I have followed in my investigation, though
different from those pursued by him, yet serve in general to
confirm Kélliker’s observations; but since my _ researches
appear to afford further information on some not unimportant
points, particularly with respect to the condition of the cells
in the mantle of Phallusia, and the fibres in that of Cynthia, I
feel justified in communicating their results.

I examined thin, longitudinal, and transverse sections of the
mantle, first in water and afterwards in succession under various
chemical re-agents, such as a solution of iodine, a solution of
iodine in chloride of zinc, iodine and sulphuric acid, solution
of caustic potass, concentrated sulphuric acid, &c., in exactly
the same way as that in which I had already examined all
vegetable tissues. The species examined were—Phallusia
mamillaris, Cynthia microscosmus, and a new species, probably
allied to Cynthia, from Chili.

I. Phallusia mamillaris—In the mantle of this Ascidian,
according to Kélliker and Loéwig, there are three layers per-
ceptible,—an internal, consisting of an epithelium with cell-
nuclei; a middle layer, which in a homogeneous substance
contains crystals and cell-nuclei; and a third layer, which
forms the chief substance of the mantle: numerous, much rami-
fied vessels proceeding from the heart penetrate the latter, and
which, at the surface of the mantle, appear to pass into other
vessels which accompany them in their course. The elements
of this layer are large, elegant cells, imbedded in a clear homo-

geneous substance, continuous with the principal substance of
pd 2

36 SCHACHT ON THE MANTLE OF CERTAIN ASCIDIANS.

the second layer. The largest of these cells, measuring on the
average 0-02—0-03’", and which were regarded by Wagner
as cartilage-cells, according to Kélliker and Liwig, correspond
with no animal cells hitherto known, except those of the
chorda dorsalis of some animals. After treatment with potass,
the epithelial cells, the nuclei, and the pigment-cells, which
occur here and there, disappear, together with the vessels ;
whilst, on the contrary, the substance of the second layer and
the corresponding substance between the cells, together with
the latter, remain undissolved, Kdlliker and Léwig therefore
regard both the substance in which the nuclei and cells lie, as
well as the membrane of the cells itself, as non-nitrogenous—
as cellulose.

The fleshy verrucose mantle of Phallusia mamillaris also,
according to my investigations, presents the three layers above
described. The innermost layer is separable as a thin mem-
brane from the rest of the substance of the mantle; upon it
lies a layer of very regular epithelial cells, a true tesselated
epithelium, the cells of which still exhibit traces of a nucleus.
This membrane itself is coloured blue by iodine and sulphurie
acid, and is of a fibrous structure, with scattered nuclei; the
epithelium acquires a brown colour. When boiled in caustic
potass, the membrane contracts, without bemg dissolved, how-
ever; and when torn in this condition, its fibrous structure
becomes still more evident. The epithelial cells disappear
under this treatment. Upon or beneath this membrane lie,
scattered here and there, large cells with granular contents,
which, when warmed, does not become fiuid, and therefore
cannot be any readily congealed fat. When these cells are
ruptured the substance breaks up into granular portions; |
regard them as pigment-cells,

The second layer, demonstrated by Kolliker and Léwig,
constitutes about 1-6th of the entire thickness of the mantle ;
it passes insensibly into the main layer; the principal vas-
cular trunks lie in this layer, and in it they give off branches
which ramify in all directions as far as the border of the
mantle. The chief vascular trunks which enter the mantle in
a radiating manner from one point of the animal (according to
Kolliker, the heart), exhibit in their interior spirally ascending
fibres, whence they resemble the trachee of insects ; this struc-
ture does not exist in the smaller branches. The substance
in which these large vessels are placed is homogeneous, with
numerous clongated and round nuclei, but here and there there
is a minute isolated cell, and still more rarely a group of
crystals. Immediately under the readily detached epithelial
membrane, the substance appears in places to be striated
(fibrous), and after boiling with caustic potass this appear-

SCHACHT ON THE MANTLE OF CERTAIN ASCIDIANS. 37

ance becomes more distinct. The entire substance of this
layer is coloured blue by iodine and sulphuric acid, the nuclei
and vessels turning yellow ; on being boiled with caustic potass
the two latter are dissolved, the substance itself contracts, but
is not otherwise altered; concentrated sulphuric acid dis-
solves it almost entirely. The third layer, which constitutes
four or five-sixths of the thickness of the mantle, com-
mences very insensibly below the large vascular trunks: it
is at first distinguishable by the appearance of cells and
the diminution of the cell-nuclei, which latter acquire a
more irregular, frequently stellate figure, and in this con-
dition strikingly resemble the bone-cells. The number and
size of the cells increase in proportion to the diminution
of the nuclei; the cells, which, at the commencement of the
layer were more elongated, become more and more rounded,
and more closely aggregated, but still not so much so as
to interfere with their spherical form. At the outermost
border of the mantle the cells again become somewhat smaller,
which is best seen by boiling a portion of the mantle from
this situation, in caustic potass. The external surface of the
mantle is irregularly beset with short blunt columns composed
of crystals ; these crystals are insoluble in hydro-chloric acid ;
sulphuric acid appears to attack them but very slowly. They
cannot therefore well be carbonate of lime, as supposed by
K6lliker and Lowig. The outer surface of the mantle, like
the imner, is covered with a tesselated epithelium, but the
existence of this epithelium is here much more difficult of
demonstration, and it does not seem to be retained in all parts.
It is most certainly seen in thin horizontal sections on the addi-
tion of sulphuric acid. In the middle, and on the outer border
of this layer, the nuclei are proportionately rare; the much
ramified branches of the large vessels extend as far as the
border of the mantle, where they terminate in clavate dilata-
tions. Sometimes, it is true, it appears as if one or other
branch of these vessels ran backwards into the substance of
the mantle, but a double vascular system, as described by
K6lliker and Léwig, I have nowhere been able to detect.

In a very thin section, under water, a peculiar, excessively
delicate marking is perceptible in the thin cell-membrane,
surrounded by the transparent interstitial substance, which
marking in some cases might be taken for a closely wound
spiral, but which, as I have satisfactorily ascertained, depends
upon a folding of the membrane, due in all probability to the
influence of the spirit in which the specimen had been kept.
The form and appearance of the cells is the same in whateyer
plane they are viewed ; they are not placed at any uniform
distances apart. At the boundary between this and the second

38 SCHACHT ON THE MANTLE OF CERTAIN ASCIDIANS.

layer the formation of new cells appears to take place in the
interstitial cellulose substance, without the intervention of a
mother cell. The cells are invariably without a nucleus or
any visible cell-contents.

Todine colours the thin, somewhat granular-looking mem-
brane of the cells in question yellowish, and the above de-
scribed marking appears then more distinctly, and minute
opaque granules show themselves in the furrows between the
folds. The interstitial substance in thin sections is scarcely
coloured ; in thicker it appears yellowish.

If a thin section be touched with a solution of iodine, which
is afterwards removed with a fine hair pencil, and a drop of
sulphuric acid added by means of a glass rod, the section is
immediately coloured a dark blue. It is not the cells which
are coloured blue but the insterstitial substance. The thicker
parts of the section do not acquire the blue colour till after-
wards, frequently not for several hours.

If, on the other hand, a similarly thin section be moistened
with the solution of iodine in chloride of zinc, the interstitial
substance remains colourless, even when the section has been
previously allowed to dry upon the glass. The cellulose of
plants on the other hand, in general, if not immediately,
yet after some time, appears to be coloured a beautiful blue
or violet by this re-agent. The cellulose of the higher Algz
(Chordaria, Fucus serratus, Chondrus crispus) behaves in this
respect like that in the mantle of Phadlusia, and is not coloured
by the ioduretted solution of chloride of zinc.

If to a thin, scarcely moist section, be added a drop of con-
centrated sulphuric acid, and its action noted, it will be seen
to take place from the edge of the section towards its centre ;
the membrane of the cells contracts, and the markings, caused
by the folds, disappear, though the minute granules contained
in the furrows remain. The cell-membrane exhibits precisely
the same re-actions as does the primordial sac of the vegetable
cell. In proportion to the contraction of the cells the inter-
stitial substance swells out, by which the distance between the
cells is increased. The swollen interstitial substance is not
optically recognizable. If now a drop of a solution of iodine
be added, and allowed to enter from the side between the slips
of glass, there appears at the limits of the intermingling fluids
a brownish violet zone of a granular consistence as seen under
the microscope. The solution of iodine is prevented by the
swollen interstitial substance from penetrating farther, but if
the cover is raised and again let fall after the solution of iodine
has become mixed with the sulphuric acid, the whole assumes
the appearance of a more or less clear, and more or less in-
tensely blue membranous substance—the swollen interstitial

SCHACHT ON THE MANTLE OF CERTAIN ASCIDIANS. 39

substance —in which tke almost imperceptible remains of the
cells are lodged.

If a thin section be treated with sufficiently strong hydro-
chloric acid, there ensues, even after several hours, no colour-
ing or other perceptible change either in the cell-membrane or
in the interstitial substance, nor have I ever succeeded by the
use of sugar and sulphuric acid in producing a manifest rose-
red colour in the probably nitrogenous cell-membrane.

If a thin section be warmed for a minute in sufficiently
strong solution of potass, it is not disintegrated ; the membrane
of the cells disappears entirely if the section were thin enough,
and the re-agent has acted sufficiently ; the interstitial sub-
stance becomes somewhat contracted ; the hollows in which
the cells had been contained on this account appear smaller.
The addition of a solution of iodine now colours the interstitial
substance yellowish, in an hour clear brown-violet ; a fresh
addition of the iodine solution exalts this colour ; after twenty-
four hours the section appears red-brown, like the colour of
burnt terra de Sienna. J[oduretted chloride of zinc solution
immediately colours a section that has been boiled in potass of
a beautiful violet blue.

If small pieces of the mantle be macerated for 23 to 3
minutes in chlorate of potass and nitric acid, the substance
during maceration assumes a citron yellow colour, which dis-
appears on the addition of water. The substance is not dis-
integrated, and may be cut just as readily after the maceration
as before it; nor is any change perceptible under the micro-
scope either in the cell-membrane or interstitial substance.

If, however, thin sections of the mantle are macerated in
the same way for only a minute, the section does not become
corrugated, assumes a yellow colour during the maceration,
which disappears in water. ‘The interstitial substance has not,
as on the application of caustic potass, become contracted, the
cells have not disappeared, though less distinctly marked than
before ; their membrane appears, as previously, rather granular,
nor is it changed in the folds. The addition of solution of
iodine scarcely produces a yellow colouring of the cell-mem-
brane, the interstitial substance is not coloured, nor does the
ioduretted chloride of zinc solution produce any effect—no
blue colour being elicited even after several hours. lodine and
sulphuric acid however produce precisely the same blue colour
of the interstitial substance as before the maceration ; the
pieces of the mantle which had been macerated 23 to 3 minutes
behave in exactly the same way towards the same re-agent.

[To be continued. ]

ROE Yi Eaves.

LecTuRES ON HisToLoay, delivered at the Royal College of Surgeons of
England, in the Session 1850-51. By Joun Quexerr. London.
Bailliere.

Amonest the many admirable arrangements of the College
of Surgeons in London is the delivery by the Professors of
courses of lectures on what may be called the science of
organization. In the lectures delivered by Professors Owen,
Paget, and Quekett, the object of the College of Surgeons in
relation to the profession of surgery is not lost sight of, but
they have the higher object in view of illustrating the great
museum which the industry of John Hunter commenced, and
of exhibiting the spirit in which that profound genius laboured
to unfold the laws of organization. Already science is deeply
indebted for the contribution which the publication of many
of these lectures has made to its literature. We may name
more especially the philosophical lectures of the Hunterian
Professor on Comparative Anatomy, as amongst the most im-
portant works of the day upon the subject.

It was not to be expected that the Council of the institution
that was entrusted with the charge of Jobn Hunter’s museum
would neglect the opportunity which recent improvements of
the microscope afforded, of prosecuting by its aid the re-
searches which that great philosopher had commenced. It
was fortunate that in Mr. Quekett they found a man whose
tastes, habits, and education peculiarly fitted him for prose-
cuting inquiries with this instrument. Unbiassed by the
views of others, not given to speculation, delighting in delicate
manipulation, and possessed of a patience unwearied as long
as new subjects were to be examined or new facts observed,
he was just the man to contribute to the histological parts
of the museum, and to demonstrate the minute anatomy of the
tissues. Under his superintendence the histological demon-
strations became speedily popular, and as the result, his
remarks on the preparations submitted to his class have been
published in the form of these ‘ Lectures on Histology.’ This
title might however mislead, as this work is not a complete
treatise on histology, nor intended to embrace the whole of
this wide field of science. They consist of a series of remarks

QUEKETT’S LECTURES ON HISTOLOGY. 41

with reference to objects and preparations which were intended
to illustrate a particular series of facts. The object of the
present volume is the elementary tissues of plants and animals,
and even these are not treated at all in an exhaustive manner.
The work therefore must not be regarded as a manual or
outline of the subject of histology, but as the remarks of an
observer whose opinions are always of value, over a wide and
important field of microscopic research.

The first part of the work is devoted to the tissues of
plants, the second to the tissues of animals. We are glad to
find that Mr. Quekett has devoted so much space to vegetable
tissues, as there can be no doubt that the best introduction to
the more difficult problem of cell-growth in animals is the
study of the phenomena presented by the cells of plants. The
vegetable and animal kingdoms, with a wonderful distinction
in form and functions, have yet relations so close, and a
dependence so absolute, that the principles which regulate the
growth and functions of one cannot be understood without
reference to the other; and researches, prosecuted by the aid
of the microscope, are every day increasing our knowledge of
the details of this great fact.

Mr. Quekett commences with an account of the old “ ele-
mentary tissues ” of the botanist, ‘‘membrane and fibre.” It
should, however, be recollected, that amongst plants there is
no membrane, as there is in some animal structures, indepen-
dent of the cells. The vegetable membrane referred to here
is slunply the cell-wall, which varies very much in form and
properties in different cells. So with fibre. We well know
there is no fibre independent of cells, and fibre is but one
form which the deposits in the interior of cell-walls exhibit.
There is no advantage to be gained in treating of these subjects
independent of the cells in which they are found.

From a chapter entitled ‘ On the Forms of Cells,’ in which
several of the principal forms of plain cellular tissue are
noticed, we pass to the contents of cells. Under the head of
‘ Starch’ we find the properties of the common forms of this
substance alluded to. Mr. Quekett adopts the term “ hilum,”
as applied to the circular spot seen in the majority of starch
granules ; but this term is objectionable, as involving the idea
of the attachment of the starch granule to the cell, which is
not the case. Fritsche’s term nucleus is better when this
spot is obvious. This nucleus is mostly seen to be surrounded
by curved lines, and which have been supposed to indicate
that the starch is composed of a series of layers which have
been consecutively deposited. Mr. Quekett however decides
this, and says “ they are confined to the cell-wall, and are

42 QUEKETT’S LECTURES ON HISTOLOGY.

most probably mere transverse thickenings or ruge in the
membrane, of which, together with its amylaceous contents,
the starch-granule consists.” This statement is at variance
with the observations of Payen and Persoz, and of Schleiden,
who maintain not only that the starch-granule is composed of
several layers of differing density, but that there is no envelop-
ing membrane, the whole granule consisting of a homogeneous
mass. Schleiden says most emphatically, as the result of a
long series of experiments on the action of iodine, that “ there
never was the most remote indication of there being any part
in the starch-granule which was not equally coloured by it.”

Speaking of the potato disease Mr. Quekett says :—

‘« Before leaving the subject of starch, allusion may be made to the re-
cently prevalent and destructive epidemic among the potatoes, which I
believe to have been a disease of the tuber, not of the haulm or leaves.
Examined in an early stage, such potatoes are found to be composed of
cells of the usual size, but they contain little or no starch ; and hence it
may be inferred, that the natural nutriment of the plant being deficient,
the haulm dies, the cells of the tuber soon turn black and decompose, and
fungi are developed as on most other decayed vegetable substances.”

This will undoubtedly explain the most prominent symptom
of the potato disease—the tendency to decomposition,—and
is a point in which the microscope confirms the result of
chemical experiment, for it has been found that the diseased
potatoes contain a larger proportion of water than those which
are healthy. A want of organizing power is evidently the
cause of this deficiency of starch, but we fear the microscope
will never tell us in what the want of this organizing force
consists.

Under the head of raphides there are some interesting
remarks, but as in the portion of the Transactions of the
Microscopical Society, which we publish in this Number,
Mr. Quekett enters so fully into this subject, we shall pass
it over, only observing that we cannot agree with him that they
are accidental bodies. In many of the plants referred to,
these bodies are constantly found, and we question if a speci-
men of any of them could be found in which these bodies
are absent. Although Mr. Quekett has separated silica from
the raphides, we cannot but think that the deposits of this
substance in the tissues of vegetables are of the same nature
as that of other inorganic compounds. It is true that the
function of silica, as deposited in the stems of grasses, palms,
and Dutch rushes (Equisetacex), is more obvious than that of
oxalate of lime in the roots of rhubarb, but the one is not
less constant than the other. In the family of Corallines we
find carbonate of lime not less necessary to their existence
than the silica of the Diatomacee. What the relation of

QUEKETT’S LECTURES ON HISTOLOGY. 43

these inorganic matters to the tissues of plants really is, may
be seen in the perfectly analogous deposit of the same
substances in the Polypiferze and Spongiade in the animal
kingdom.

In allusion to the distinctions between the Diatomacez and
Desmideex, Mr. Quekett says that the latter have a horny, in
place of a siliceous structure. The horny character, however,
of the Desmidez is not dependent on gelatine but on cellulose,
as we have frequently observed, by the application of sul-
phuric acid and iodine, when the cellulose is converted into
starch and coloured blue by the iodine.

The use of the Diatomacez as food as they occur in the
Berg-mehl of Sweden, seems to be regarded by Mr. Quekett
as dependent on the silica they possess. We think it is much
more likely to be on account of the layer of organized matter
by which their siliceous skeletons are surrounded, and if we
mistake not, this is the explanation given by Ehrenberg, who
first demonstrated the true nature of this interesting substance.
The part performed by Diatomacez in the creation is not yet
fully understood. Of all organisms they are most abundant.
Dr. Hooker found them discolouring the seas of the South
Pole, and in the lava of the voleanic mountain Victoria. They

are found in the greatest abundance in rivers, lakes, ponds,
and ditches, and if in the purest water an organic being or
two are found to be present, they are sure to be Diatomacee.
The late Mr. Edwin Quekett discovered a highly interesting
set of forms of them in the guano of Peru, and his brother
suggests that this manure may owe something of its value to
the siliceous matter which it thus contains. We have much
to learn with regard to the history of these beings, the existence
of which the microscope alone informs us, and we are glad
to know that we are shortly likely to have the results of
several years’ careful examination of them from the Rev. Mr.
Smith. Messrs. Ralfs and Jenner have also been labouring at
this department of inquiry, and have partly promised a work
on the subject, through the means of the Ray Society.

Under the head of ‘Sclerogen,’ Mr. Quekett has given a
number of examples of those forms of cellular tissue in which
the cell-walls are of unusual thickness and hardness. A
knowledge of these is not only interesting, as illustrative of
the great variety of cell-growth, but is not unfrequently of
practical value, as the following cases prove :—

“A knowledge of these hard structuresis often of considerable impor-
tance, much more so, indeed, than many are apt to imagine. The fol-
lowing is an example of the practical utility of such an acquaintance with

minute structural anatomy :—About two years since, I received from a
medical gentleman in the country, some specimens mounted as micro-

44 QUEKETT’S LECTURES ON HISTOLOGY.

scopic objects, that had been passed from the bowels by a female. One of
them I found to be the cuticle of a plant, and this turned out subsequently
to be the cuticle of a gooseberry ; the other puzzled me, but I made up
my mind that it also was of vegetable origin, and that it was, in all pro-
bability, the testa of some seed. I wrote to my correspondent to this
effect, but the patient denied having eaten any dried fruit for the space of
twelve years, and the physician, believing the statement of his patient,
considered that the microscopist was in error. I, however, still maintained
my point, and when preparing the series of specimens known as hard
tissues, for the Histological Catalogue of the College of Surgeons, I
examined, among other things, the tamarind, and in the testa of the seed
found the disputed structure. I subsequently learned that the patient
was the daughter of a grocer, and might have had free access to the
tamarind jar. ‘This is another instance of the value of the microscope to
our profession.”

Vegetable physiologists would have been glad of Mr.
Quekett’s opinion on the structure of the embryo, and espe-
cially on the question of the entrance of the pollen-tube into
the sac of the embryo. He has not, however, alluded to this
subject. He has, however, some remarks on the structure of
Spermatozoids or Phytozoa, which are now known to exist in
so many of the Cryptogamia. He has not examined these
extensively. Although he has not alluded to the movements
of these bodies as dependent on ciliary motion, there is
no doubt that in the ferns at least they are supplied with
cilia, which produce their movements. This subject is one
which still offers a rich field of investigation for the micro-
scopic observer. To those who wish to pursue this subject,
we would recommend Dr. W. Hofmeister’s work on the
Germination, Development, and Fructification of the higher
Cryptogamia. (Vergleichende Untersuchungen der Keimung,
Entfaltung, und Fruchtbildung hoherer Kryptogamen, 4to.,
Leipsic, 1851), and also the excellent report on this subject
by Mr. Henfrey in the last volume of the Transactions of the
British Association. :

From plain cells and their contents we come to fibro-
cellular tissue, to plain vascular tissue, such as that which is
called woody, and the various forms of fibro-vascular tissue.
In his treatment of these subjects the Professor has not followed
any definite plan. All vegetable tissue is a modification of the
cell, and any classification artificial. For practical purposes
the term vascular may be applied to cells or tissue longer than
it is broad, whilst cellular should be confined to tissue that is
not longer than it is broad, and they may each be called fibro-
vascular and fibro-cellular, as they present fibrous deposits, or
their modifications in the interior. In speaking of the vegetable
tissues used in the arts, Mr. Quekett has pointed out how the
microscope may be successfully employed in distinguishing
the various kinds of woody fibre used in the manufacture of

QUEKETT’S LECTURES ON HISTOLOGY. 45

clothing. The microscope may thus be made to throw light
on the habits and manners of nations of antiquity. Thus it
has shown that all Egyptian mummy-cloth is made from the
fibres of the flax, whilst it has demonstrated that the mummy-
cloth of Mexico is cotton ; thus at once throwing a light on
the habits of the ancient inhabitants of the New and Old
' World; the one being engaged in the culture and manufacture
of cotton, the other in that of flax.

The analogy between the structure of spiral vessels and the
trachee of insects has not been lost sight of, and some in-
teresting instances of both are given. Similar as these things
appear we very much question if their mode of development is
the same. They afford interesting examples of a principle
which we often see carried out in nature of the greatest amount
of strength with the least amount of material. ‘The importance
of this in insects will be at once felt when we reflect that
many of them spend the greater part of their existence sus-
pended in the air by means of their wings. We also find the
spiral vessels of plants in positions where the same principle
can be clearly seen to be of advantage. Whatever may be the
resemblance in structure between these two parts there is no
reason for supposing an identity of function. Reasoning from
analogy of structure to that of function is always very unsound,
for even amongst structures that are homologous we frequently
find variety in the functions performed. ‘Take the wings of
a bird and the upper extremities of man, the swimming
bladder of the fish, and the lungs of the mammalia.

In the section on spiral vessels Mr. Quekett mentions a fact
that we do not remember to have seen previously noticed, the
existence of membrane that tears up and unrolls in a spiral
manner, This has been observed in the hairs found on the
outside of the fruit of Cycas revoluta. There is one other
subject we would allude to before leaving the botanical sec-
tion, and that is the lactiferous or milk-vessels of Schultz.
The branched character of these vessels makes them quite ex-
ceptional amongst vegetable tissues. It has been asserted that
they are not true tissue at all, but are intercellular passages
which have acquired the appearance of vascular walls from the
deposits of the fluids which pass through them. At any rate
we know little or nothing of their development, and this is
a subject open for investigation at the present moment.

This part of the work concludes with the following
sentence :—

“One great object which I have kept in view throughout, has been that
of endeavouring to impress on you the fact, that each cell of a plant should

be considered as having an independent or individual existence ; that in
one situation it may secrete colouring matter, in another starch, gum

462° THE MICROSCOPE AND ITS APPLICATION.

sugar, oil, &c.; and in another the material for the reproduction of its
species.”

We are convinced that too much importance can scarcely
be attached at the present day to the study of the cell as. an
individual. Many of the theories of vegetable function which
have been hitherto received will not bear the test of an accurate
knowledge of the functions of the individual cell. The young
vegetable physiologist cannot do better than commence his
studies, microscope in hand, with observations on the develop-
ment and functions of the individual cell.

Want of space compels us to stop here: we shall probably
recur to the remaining part of Professor Quekett’s work in our
next number.

Das Mikroskop, und seine Anwendung, §c. (The Microscope
and its application, especially to Vegetable Anatomy and Phy-
siology.) By Dr. Hermann Scuacut. Berlin, 1851.
Pp. 200.

Tue deservedly high reputation of Dr. Schacht as an
accurate microscopical observer and excellent phytologist,
and which has recently been much enhanced by his recent
work on vegetable histology,* renders a book on the micro-
scope and its use, from his hands, well worthy of consi-
deration and respect. The limited scope of the present work,
which is confined almost exclusively to botanical subjects,
is much to be regretted. Had a chapter or two, having
reference to the modes of procedure to be adopted in the
investigation of animal tissues and other subjects, and in
the same precise and satisfactory style, been added, the work
would constitute a very complete and comprehensive manual
of microscopy. The subject, however, to which it is more
particularly devoted—the structure and development of vege-
table tissues—is in itself one of great general interest and
importance, and the author’s treatment of it such as to justify
our highest commendation.

After a few sensible introductory remarks on the use of the
microscope in general, and the difficulties at first attendant
upon its employment, the author proceeds to a description
of the compound microscope. As, however, he appears to be
familiar only with instruments of continental make, and to be
altogether unacquainted with any of English construction, and
consequently with many of the more recent improvements,
introduced chiefly by English makers, not only in object-
glasses, but more especially in the various modes of illumi-

* Die Pflanzenzelle. Die innere Bau und das Leben der Gewiichse.
Berlin, 1852. Pp. 472.

THE MICROSCOPE AND ITS APPLICATION. 47

nation, which have latterly occupied so much and so deservedly
the attention of opticians, it is not necessary farther to refer
to this part of his work than to observe that he gives the pre-
ference, above all other continental instruments, to the larger
microscope by Oberhauser of Paris. This much-vaunted in-
strument we have not seen, but, from the description and
* figure of it given by Dr. Schacht, its very great inferiority, in
the mechanical arrangements of the stand at all events, to those
of our London makers, is at once apparent.

One result of the Great Exhibition of last year was incon-
testably to prove the superiority of English microscopes ; and
it is clear also from Dr. Schacht’s observations,—and he boasts
of an extended acquaintance with the microscopes of nearly
all continental makers of any eminence,—that what he con-
siders an instrument of the best possible kind would in most
respects here be regarded in a very different light. So much
in justice must be said on the part of English opticians.
Can the same favourable comparison be drawn between
English observers and their continental brethren? In some
respects, and especially, perhaps, with reference to animal
physiology, anatomy, and pathology, we are inclined to think
it might, in others certainly not; but in any case it should not
be forgotten that the extreme convenience, elegance, and, as it
may be termed, luxury, of a first-rate English microscope, are
quite unessential in the prosecution of research, and many an
ardent aspirant may be glad to know that, having really good
object-glasses, he may with a very simple instrument confi-
dently approach almost any branch of microscopical inquiry.

Having described the usual appurtenances of a microscope,
and the mode of using them, the author gives the following
list of chemical re-agents useful in microscopical inquiries, and
of preservative fluids, which we have thought it might be
useful to extract :—

£1. Alcohol, principally for the removal of air from sections of wood and
other preparations ; also as a solvent for certain colouring matters.

“<2, dither, chiefly as a solvent for resins, fatty and other essential oils,
&c.; also useful for the removal of air.

“<3. Solution of Caustic Potass, as a solvent for fatty matters; also of
use occasionally, in consequence of its action upon the rest of the cell
contents and thickening layers. This solution acts best upon being
heated.

‘© 4, Solution of Iodine (iodine 1 grain, iodide of potassium 3 grains, dis-
tilled water 1 ounce), for the coloration of the cell membrane and of the
cell contents.

“5. Concentrated Sulphuric Acid, employed principally in the examina-
tion of pollen and spores.

“6. Diluted Sulphuric Acid (three parts acid, one part water), for the

coloration of cells previously immersed in the iodine solution. The pre-
paration is first moistened with the iodine solution, which is afterwards

48 THE MICROSCOPE AND ITS APPLICATION.

removed with a hair pencil, and a drop of sulphuric acid added by means
of a glass rod; the preparation is then immediately covered with a piece
of glass. The action of the sulphuric acid and iodine, as well as that of
the iodized chloride of zinc solution, is not always uniform throughout
the whole surface of the preparation. The colour is more intense where
the mixture is more concentrated ; it frequently happens that many spots
remain uncoloured. The colour changes after some time, the blue being
frequently changed into red after twenty-four hours. .

“7, A solution of Chloride of Zinc, Iodine, and Iodide of Potassium.—
A drop of this compound solution, added to a preparation placed in a little
water, produces the same colour as iodine and sulphuric acid. This solu-
tion, which was first proposed and employed by Professor Schulz of Ros-
tock, is more convenient in its application than iodine and sulphuric acid,
and performs nearly the same services, whilst it does not, like the sulphuric
acid, destroy the tissues tv which it is applied. ‘The precise composition
is as follows :—

“© Zinc is to be dissolved in hydrochloric acid, and the solution, in contact
with metallic zinc, is to be diluted to a syrupy consistence, and the solu-
tion must then be saturated with iodide of potassium. lodine is then to
be added, and the solution, if necessary, diluted with water.

“8, Nitric Acid, or, what is better, chlorate of potass and nitric acid, as
an agent to effect the isolation of cells. The mode of employing this
means, also discovered by Professor Schulz, is as follows :—The object—a
thin section of wood, for instance—is introduced, with an equal bulk of
chlorate of potass, into a long and moderately wide tube, and as much
nitric acid added as will at Jeast cover the whole. The tube is then
warmed over a spirit-lamp; a copious evolution of gas takes place, upon
which the tube is removed from the flame, and the action of the oxydizing
agent allowed to continue for two or three minutes. ‘The contents of the
tube are then poured into a watch-glass with water, from which the
slightly cohering particles are collected and placed in a tube, and again
boiled in alcohol as long as any colour is communicated. ‘They are again
boiled in a little water. The cells may now be isolated under the simple
microscope by means of needles. ‘The boiling with nitric acid and chlorate
of potass should never be carried on in the same room with the micro-
scope, the glasses of which may suffer injury from the vapours. Thin
sections of vegetable tissue are warmed for half or a whole minute in a
watch-glass ; boiling is here unnecessary. The section is taken out, and
treated with water in a watch-glass.

“9. Oil of Lemons, or any other essential oil, for the investigation of
pollen and spores.

“10. A moderately strong solution of Muriate of Lime (one part dry
muriate of lime, and three parts distilled water), for the preservation of
microscopical preparations. This is applicable to most things, even for the
most delicate preparations, excepting starch. If it is desired to keep a
preparation, which is not to be retained permanently, for some days, a
small drop of this solution may be placed upon it, and the whole placed
under a glass cover to keep it from dust.

“11. Glycerine, also for the preservation of microscopical preparations.
It is well adapted for the preparation of cells containing starch, which re-
mains unchanged by it. In starch grains, exhibiting a laminated structure
—as, for instance, in potato starch—the lamination is usually not apparent
for the first few hours, but after about twenty-four hours it becomes more
evident than before.

“12. Copal Varnish and Canada Balsam, also used for the preservation
of microscopic objects. Both substances can only be employed in the case
of a few thin sections of wood, especially of fossil woods; both render the
object more transparent than the solution of muriate of lime.

THE MICROSCOPE AND ITS APPLICATION. 49

13. Lastly may also be enumerated a pretty strong solution of Car-
bonate of Soda and also Acetic Acid, which latter, however, is more
especially useful in the investigation of animal tissues.”

To the above may be added a test for protein compounds,
which is described by the author in his larger and more recent
work, ‘ Die Pflanzenzelle.’ This test is composed of sugar
and sulphuric acid, and is thus employed:—A very thin
section or portion of the tissue to be examined is placed in a
drop of simple syrup. This is then removed by means of a
hair pencil, and a drop of sulphuric acid (three parts acid, one
part water) added; the red colour usually does not appear till
after the lapse of about ten minutes,

The third chapter contains general rules for the use of the
microscope, and for the proper disposition and preparation
of objects ; from which, however, though all useful and con-
cisely expressed, there is little of novel nature to extract,
Dr. Schacht is of opinion, in which we cannot from expe-
rience but agree with him, that whoever has regard for his
eyes will never employ the microscope for prolonged investi-
gation by artificial light. In his directions for making thin
sections of tissues, he recommends that, in the case of objects
whose consistence differs in different parts, the section should
be carried from the harder into the softer portion. He also
in some cases recommends a procedure which is doubtless
familiar to most of our readers, viz.: in the making of a thin
section of a very minute yielding substance, to enclose it
between two pieces of cork, and to slice the whole together.
It is also useful sometimes to saturate the object with mucilage,
which is to be allowed to dry slowly ; in this way very deli-
cate tissues may be sliced or otherwise divided without injury,
and with great facility.

The fourth, fifth, and sixth chapters enter more specially
upon the histology of vegetable tissues, and the modes in
_ particular cases of pursuing its investigation. They contain
matter of great utility, but do not admit of condensation, In
all observations, Dr. Schacht strongly recommends the making
of drawings of everything worth note observed. He strongly
deprecates the making of mere diagrammatic figures, which
only convey the momentary impression made upon the ob-
server; in all cases an accurate drawing of the object,
conveying “ the truth, the whole truth, and nothing but the
truth,” should, if possible, be made: and in all cases where
it can be employed, he strongly recommends, and himself
always uses, the camera lucida,

The seventh chapter is devoted to the subject of making
drawings from the microscope, and contains many sensible,
useful, and minute directions, especially with respect to
colouring.

VOL, I. E

50 THE MICROSCOPE AND ITS APPLICATION,

The work concludes with a chapter upon the preservation of
microscopic objects, but in which we do not notice anything
sufficiently novel to warrant extraction, except one proceed-
ing, which, as we have had an opportunity of seeing, is well
worth following, and may perhaps be novel to some. It is
the mode of preserving preparations of vegetable tissues in a
solution of muriate of lime, and which, from its simplicity,
efficacy, and permanence, appears to have much to recommend
it. It is as follows :—

‘« A slip of glass of convenient size being perfectly cleaned, strips of paper
are gummed across it, dividing it into as many compartments as may be
desired. ‘The strips at each end are rather wider than those between the
divisions. These strips of paper serve not only for the subsequent joining
of the two glass slips together, but also to prevent the pressure upon the
preparations. The paper, therefore, of which the divisions are formed,
should not be thinner than the objects, nor, on the other hand, should it be
much thicker, as in that case the preparations would lie too loose.

<< When these strips of paper are dry, and the glass again carefully cleaned,
a drop of the muriate of lime solution is be placed in the centre of each
compartment by means of a thin glass rod. It is advisable first to breathe
upon the glass, as the drop of solution then adheres more readily to the
surface. The objects to be set up require to be most carefully prepared.
Preparations of recent soft objects are rarely treated with alcohol, whilst,
on the other hand, sections of wood must always first be immersed in
alcohol to remove resinous matters and air; but they must not be trans-
ferred immediately from the spirit to the muriate of lime solution—they
must first be placed in a watch-glass in water, in order to remove the alcohol.
From the watch-glass they may be carefully taken by means of a hair
pencil, and conveyed to the drop of saline solution destined for their recep-
tion. Itis often in this proceeding requisite to place the watch-glass upon
a dark ground, in order to render the minute objects visible. When all
the preparations are duly placed on the glass slip, it is brought under the
simple microscope, and the objects properly laid out by means of needles
or otherwise, and at the same time foreign particles of dust, &c., removed.

“In the conveying of the preparations, with the hair pencil, from the
water to the muriate of lime solution, a dilution of the latter is unavoid-
able. It is, therefore, very necessary to remove, by means of a larger,
perfectly clean pencil, the greater part of the solution in which the pre-
paration is lying, which with a little care may readily be done without
disturbance of the object. The fluid thus removed must then be replaced
by an equal quantity of fresh solution. The size of the drop must be re-
gulated according to the thickness of the paper employed to form the
divisions. The drops of fluid and the contained preparations being thus
arranged, each in the centre of its own division, and the latter properly
laid out so as to exhibit clearly what they are intended to show, a little
mucilage is smeared over each of the strips of paper, and the covering
glass carefully placed upon the other, and pressed upon the divisions so
as to cause it to adhere to them. The ends of the slips are then covered
fee paper, upon which are written remarks upon the preparations, with a

te, &c.

“‘ The chief difficulty in the setting up of preparations in this way con-
sists in arranging the due quantity of the muriate of lime solution. If this
be too small, the preparation will be uncovered by it on one side ; and if too
great, the fluid comes in contact with the paper forming the strips, and,
being absorbed by it, the preparation is equally left dry. In neither case,

THE MICROSCOPIST. 51

however, is it injured, as it is always saturated with the solution; but as
in this state it is useless for the purpose of examination, it is frequently
necessary to repeat the entire process. This is done by immersing the
slide in water, and, when the slips of glass are separated, the preparations
are to be again laid out in the way above described. When the process,
however, has been duly effected, no further care of the preparation is
requisite, except the always keeping it lying flat.”

Glycerine may be employed in the same way; but the
author appears to think that in the employment of this fluid
it is necessary to close the edges of the space between the
glasses with some air-tight cement.

THE Microscorist ; or a Complete Manual on the Use of the Microscope.
By Josrrn H. Wytues, M.D. Philadelphia. Lindsay and Blakiston.

Tue history of the microscope, like that of many other useful
human inventions, has been a chequered one. When first
brought into use at the end of the seventeenth and the beginning
of the eighteenth century extravagant expectations were formed
of its value—expectations which were almost justified by the
discoveries of Swammerdam, Hooke, Leeuwenhoek, and others.
It failed, however, to realise these brilliant hopes, and we
find the science of observation progressing rapidly from the
middle of the eighteenth to the beginning of the nineteenth
century without the aid of the microscope. Linnzus, the
great presiding genius of natural history at this period, had
put his ban upon this instrument, and publicly announced his
opinion of its worthlessness in the pursuits of the naturalist,
It, however, maintained its position in the toy-shops, and
though disregarded by the man of science, it was a successful
means of exciting the wonder of the ignorant in the hands of
the mountebank. [Even after the improvements of the micro-
scope in the present century by Brewster, Lister, and others,
which made it once more an instrument of observation, and the
discoveries of Brown, Ehrenberg, Miiller, and their contem-
poraries, it has not lost its hold on the public mind as a source
of wonder, and a toy with which to pass away hours that would
otherwise be found wearisome enough: We would not on this
account propose a classification of those who possess micro-
scopes into those who use them as toys and those who use them
as philosophical instruments. It is certain, however, that the
two classes exist and they probably run one into the other at
many points, and we only allude to the subject here by way of
warning to those who use or write upon the microscope to avoid
the tendency to regard it as a mere instrument of amusement.
The simplest combination of lenses that can be bought at a

E2

Fr THE MICROSCOPIST.

toy-shop may be made a means of instruction to the children for
whom they are made. The microscope is, in fact, but an in-
strument or tool, and in this respect is like all others by the use
of which certain ends can be attained and objects effected which
could not be without its employment. As cutting with asharp
instrument is better than tearing with the nails, so vision with
the microscope is better than with the naked eye. Its use is,
therefore, as extensive as that of the organ which it assists, and
it cannot be regarded as the property of one branch of science
more than another. It is true that in revealing the intricate
structure of organized beings it has been more extensively
employed by the physiologist and naturalist than by other
scientific inquirers, but it cannot be claimed exclusively for
histology or any other branch of science. But whatever may
be the department of inquiry in which this important imstru-
ment is employed, the general principle of its construction
and use are the same, hence the demand for books treating of
its structure, and explaining the manner of its use and appli-
cation. Of the various treatises that have been devoted to this
subject in the European languages, we have no hesitation in
pronouncing that by Professor Quekett as far the best, and
we hope in our next number to have an opportunity of noticing
the second edition of this excellent work. Still we have
always regarded Mr. Quekett’s work as too minute and ex-
tended, as well as too expensive, to serve the purposes of those
who only want an explanation of the instrument and a few
plain directions for its use. The little work published in
America by Dr. Wythes in size and price is evidently more
adapted for general use. Its plan and contents are so evidently
founded upon the work of Mr. Quekett that we wonder the
author did not at once acknowledge how largely he is indebted
to that gentleman’s labours. It is one of the grievances that
literary men have to complain of in this country, that their
works are reprinted in America without their obtaiming any
profit from the wide sale they meet with in that country, and
the least they have to expect is, when their works are reprinted
or extensively drawn upon, that the debt be acknowledged.

As an instance of how much Dr. Wythes is indebted to the
English professor, we would quote the chapter on Test-objects,
which is scarcely more than an abstract of the chapter on the
same subject in Mr. Quekett’s book, and in which no pains
have been taken by an alteration of expression to conceal the
source of the information. The plates illustrative of this sub-
ject are also copied from Mr. Quekett’s work, as well as many
others.

Although Dr. Wythes’ work is intended for all who use

THE MICROSCOPIST. DO

the microscope, it is very evident that his own acquaintance
with this instrument has been almost exclusively confined to
animal tissues. Thus, speaking of the “ circulation in plants
termed cyclosis,’ he says, “ It can be observed in all plants
in which the circulating fluid contains particles of a different
refractive power or intensity, and the cellules are of sufficient
size and transparency. Hence all lactescent plants, or those
having a milky juice, with the other conditions, exhibit this
phenomenon.” He has here confounded the general move-
ment of the sap witnessed in lactescent plants with cyclosis.
Again, in a chapter somewhat singularly called the “ cell-
doctrine of physiology,” in speaking of the development of
cells within other cells, he says, ‘‘each granule of the nucleus
has the power of developing a cell ;”” and without any allusion
to this as a controverted opinion, or to any other form of cell-
development, he leaves the subject. It would perhaps be
better in works of this kind that all physiological views and
general principles arising out of the investigation of particular
structures should be omitted. All that is required is a refer-
ence to the various classes of objecis in which the microscope
is found of advantage, and directions as to the best methods
of examining such objects. In the present instance we find
no directions given as to the best way of exhibiting tle cyto-
blast or the objects best fitted for showing it. Another
omission in this book of more importance is the entire absence
of any allusion to the use of re-agents in the examination
of animal and vegetable tissues. The aid of chemistry has
become so important in distinguishing certain tissues under
the microscope, that too much stress can hardly be laid upon
it in any directions for its use.

The work is illustrated with a great number of wood-cuts ;
some of those of microscopic objects are very coarsely done.
This is a pity, as too great pains cannot be taken in making
evident in drawing those distinctions which are evident with
the microscope. The wood-cuts, for instance, of the caudate
cells, in figs. 36, 40, 41, and 42, are not sufficiently different
to lead a young microscopist to the belief that by their means
a distinction may be made out between an innocuous and a
malignant tumour. We are sorry to have to find so much
fault with this book, but it contains the elements of a useful
volume, and, if we*may judge from its sale in this country,
the present edition is likely soon to be sold off, and to afford
Dr. Wythes an opportunity of correcting its errors, acknow-
ledging his debts, and extending his work in those directions
in which it is most deficient.

NOTES AND CORRESPONDENCE.

New Mernuops or Constructing THE THIN GLass AND
spuitt Cetts For Preserving Opsects 1n Fiuip.—In conse-
quence of the difficulty of making the thin glass cells now in
use, they are not so frequently employed by microscopists
as they would be if their manufacture were more simple,
and they could be obtained at less cost. One method of
making these thin cells consists in grinding down a thick
section of glass tube, or thick glass bottle, until the requisite
tenuity has been obtained. This process is obviously quite as
laborious as that of drilling through several squares of the thin
glass cemented together by marine glue, and afterwards sepa-
rating them for mounting on the glass slide. By either of
these processes"it is obviously difficult to obtain cells varying
much in size, the usual dimensions of the cell being not more
than half an inch in diameter ; and it is almost impossible to
make large shallow glass cells by either of the above-mentioned
methods.

Method of making the thin Glass Cell— Some time ago a
very simple method of perforating the thin glass occurred to
me, which bas been found to answer exceedingly well, and it
has this great advantage, that the microscopist can make cells
for himself of almost any dimensions required.

The principle of the process depends upon the fact that a
crack will not extend across any part of a piece of thin glass
which is fixed by marine glue to any firm surface to which it
is capable of adhering. ‘The edges of the thin glass may be
broken in all directions, but the crack will extend only up to
the marine glue, and no farther. If a piece of thin glass be
fixed by marine glue to one of the thick sections of tube used
for making cells in which injections are mounted, and allowed
to cool, a hole may be made in the centre with a file, which
may then be carried round the edges, and a thin glass cell
exactly the size of the thick one is produced. It is removed
by heating the glass, and may then be transferred to a slide
and fixed at once, or the glue adhering to it can easily be re-
moved by soaking it for a short time in potash. The surfaces
may be roughened, or the cell may be ground thinner by rub-
bing it on a flat surface with emery-powder in the usual way.

MEMORANDA. 5D

All that is requisite, then, to make thin glass cells of any
required form and dimensions, is to obtain a perfectly flat,
thick ring, to which the glass may be cemented, and in a few
minutes several thin cells of large size may be made, and at
very trifling cost.

It may not be out of place here to describe a very simple
method of cutting the circular glass covers for thin glass cells.
For this purpose several beautiful forms of apparatus have
been devised ; amongst others may be mentioned that of Mr.
Darker, by aid of which circles of any diameter may easily be
cut. A very simple form of apparatus may be made by sol-
dering on each side of
several common brass cur-
tain-rings a straight piece
of wire, as in the figure,
by means of which the
ring can be held firmly
by two fingers against
the thin glass lying on a
perfectly flat surface. The writing diamond is then carried
round the inside of the ring, and the circular piece of glass
is readily obtained. The rings may be purchased of any size,
and by a little bending they may be formed into a very good
oval for cutting thin glass of this form.

Method of makiny the built Glass Cell——The usual plan of
constructing the deep glass cells, by joing together several
slips of thick plate glass, the edges of which have been ground
perfectly flat, and cementing them at the angles with marine
glue, is a process of considerable labour. For some time past
I have been endeayouring to devise a method by which these
cells could be more readily made, as their advantage over
bottles for mounting many preparations is obviously great.
The process about to be detailed requires some practice, but,
when this is acquired, cells may be made much more rapidly
than by the old method,’ and have the advantage of possessing
fewer joins.

A slip of plate glass, of the required depth, of about the
eighth of an inch in thickness, and of sufficient length to make
all four sides of the cell, is taken. The length of each side is
to be accurately marked upon it with a spot of ink, and in
these situations the glass is to be carefully and very gradually
raised to a red heat in the blow-pipe flame, and then bent
so as to form a good angle; care being taken not to twist
the glass in the slightest degree. The other angles are
formed in the same manner, each being cooled as gradually
as it was heated. The ends are to be afterwards cemented

6 MEMORANDA.

cr

together by heating in the blow-pipe. If the last side when
bent round should be found to be too long, a small portion can
be cut off by aid of the diamond, and, with a little care in
heating the ends and pressing the glass together when in a
softened state by a small piece of wire, an excellent juncture
may be made; or, if preferred, the join may be effected in the
centre of one of the sides. In this way cells may be made of
half an inch in depth, or rather more, and of any required size.
The great difficulty in constructing cells in this way arises
from the glass cracking im the process of heating or cooling,
and from the tendency of the sides to twist when the glass is
softened in the position of the angles. The latter difficulty is
soon overcome by practice ; the former would be avoided if,
instead of the ordinary plate glass, flattened and well-annealed
flint glass were employed ; and I believe that, with this mo-
dification, the construction of cells would be much simplified,
and they might be made at a cost far less than that for which
built glass cells can now be obtained. When the angles are
formed and the glass joined, the surfaces are ground flat in the
usual way ; and if care be taken to prevent twisting, this part
of the process is soon executed. After grinding they are fixed
to a flat plate-glass slab with marine glue. I have succeeded
in making several cells in this manner which have now had
preparations in them for upwards of two years.—LionEx S.
Brae, M.B.—27, Carey Street, Aug. 1852.

STRUCTURE OF THE EprperMiIs OF THE PETAL OF THE GERANIUM.
—The petal of the Geranium is one of the most common and
beautiful objects in microscopic cabinets. The usual way of
preparing it is by immersing the leaf in sulphuric ether for a
few seconds, allowing the fluid to evaporate, and then putting
it up dry. Another is by simply drying the petal, immers-
ing for an hour or two in spirits of turpentine, and then put-
ting it up in new Canada balsam.

By neither of these plans is the true structure shown; we
can recognise the mamillary process of each cell, but not the
few hairs which surround their margin.

The only way in which I have succeeded in preserving
these is the following :—I first peel off the epidermis from
the petal, which may readily be done by making an incision
through it at the proximal end of the leaf, and then tearing it for-
wards by the forceps. 'lhis is then arranged on aslip of glass,
and allowed to dry ; when dry, it adheres to the glass ; place
on it a little Canada balsam diluted with turpentine, and boil
it for an instant over a spirit-lamp ; this blisters, it, but does
not remove the colour. Cover then with a thin slip to pre-
serve it. On examination many cells will be found showing

MEMORANDA. 57

the mammilla very distinctly and the score of hairs surrounding
its base, each being slightly curved and pointing towards the
apex of the mammilla. It is these hairs and the mammilla
which give the velvetty appearance to the petal—Tnomas
Inman, M.D. Liverpool.

On tHE Formation oF Dorrep TissuE.—Bothrenchyma
forms a very popular microscopic object. It is interesting
to examine the way in which it may be formed. It may
be produced, as in rhubarb, by the filling up of inter-
spaces between fibres until a small pit only remains: or,
as in the Alnus serratula, by a number of lines, arranged
at first like those of a ladder, then united by transverse
ones forming a grating, the angles being filled up and rounded
last: or, as in the Populus tremuloides, by an uniform deposit
over the whole membrane. It is generally known that
bothrenchyma does not exist in coniferous wood, but in
some varieties a dotted tissue may be distinctly made out,
situated in the medullary rays. The wood in which I have
found it is that of which eau de Cologne boxes are made. Its
rudiments are to be found in common deal. The formation is
readily accounted for. Wherever the two sets of fibres or cells
cross each other, their angles are filled up, and they form
apparently a grating of round holes instead of square. They
could never be mistaken for genuine bothrenchyma.

I have heard many suggestions as to the use or intention of
these little pits ; passing by the obvious one of their promoting
the easy transmission of fluid, the following seems the most
striking. They are intended to unite the utmost possible
strength with the utmost possible lightness—e. g., if an en-
gineer wanted to cast a pillar which should combine these two
qualities, he would mould it on a plan precisely similar to a
dotted duct.—Izip.

Opricat Properties 1N A SALT OF QuininE.—Dr. Hera-
path, of Bristol, has recently described a salt of quinine,
which has remarkable polarizing properties. The salt was
first accidentally observed by Mr. Phelps, a pupil of Dr.
Herapath’s, in a bottle which contained a solution of disul-
phate of quinine. The salt is best formed by dissolving disul-
phate of quinine in concentrated acetic acid, then warming
the solution, and dropping into it carefully, and by small
quantities at a time, a spirituous solution of iodine. On
placing this mixture aside for some hours, brilliant plates of
the new salt will be formed. The crystals of this salt, when
examined by reflected light, have a brilliant emerald green
colour, wit! almost a metallic lustre ; they appear like portions
of the elytra of cantharides, and are also very similar to mur-

538 MEMORANDA.”

exide in appearance. When examined by transmitted light
they scarcely possess any colour-—there is only a slightly olive-
green tinge ; but if two crystals, crossing at right angles, be
examined, the spot where they intersect appears as black as
midnight, even if the crystals are not 1-500th of an inch in
thickness. If the light be in the slightest degree polarized—
as by reflection from a cloud, or by the blue sky, or from the
glass surface of the mirror of the microscope placed at the
polarising angle 56° 45’—these little prisms immediately
assume complementary colours: one appears green, and the
other pink, and the part at which they cross is a chocolate or
deep chestnut brown, instead of black. As the result of a
series of very elaborate experiments, Dr. Herapath finds that
this salt possesses the properties of tourmaline in a very
exalted degree, as well as of a plate of selenite, so that it
combines the properties of polarizing a ray and also of depolar-
izing it. Dr. Herapath states, in his last communication to
the ‘ Pharmaceutical Journal’ on this subject, that he has suc-
ceeded in making an artificial tourmaline large enough to
surmount the eye-piece of the microscope, so that all experi-
ments with those crystals upon polarized light may be made
without the tourmaline or Nicholls prism, He says that the
brilliancy of the colours is much more intense with the
artificial crystals than when employing the natural tourmaline.
As an analyser above the eye-piece, it offers some advantages
over the Nicholls prism in the same position, as it gives a
perfectly uniform tint of colour over a much more extensive
field than can be had with the prism.

DesquaMATION OF PuLMoNnARY ArR-CELLs.—Attention has
recently been called to the value of the microscope in diseases
of the kidney. It has frequently been appealed to in diseases
of the lungs, but with less success. My imtention is to show
that in some rare cases some similarity may be found micro-
scopically between the one and the other.

Dr. G. Johnson has pointed out how constantly one form
of inflammation of the kidney shows itself by epithelial de-
squamation, and how generally the casts of the urmary tubes so
produced may be found in the urine.

I have on one occasion discovered the traces of a similar
process in the lungs. A friend forwarded me some expectora-
tion from a patient, with a request that I would examine it,
and give an opinion, if I could, whether the case was one of
phthisis or bronchitis, a question her attendants were unable
to solve. As the examination was somewhat instructive, I
will give its detail. The first specimen I examined con-
tained abundance of pus and mucous granules, a number of oil

MEMORANDA. 59

globules, and some scattered particles of starch. There was
also a fragment or two of fibrous tissue, which might or might
not be a portion of broken-down lung. I soon succeeded in
obtaining larger specimens of this, and found it was a cell-
structure too regular for any in the animal world. By char-
ring, it gave a vegetable smell, and reminded me of burnt
bread. I then procured some bran, and found that it re-
sembled it closely. The first diagnosis was then, that the
patient had been eating bread and butter. I next took some
of the sputa and agitated them with water for a considerable
time, boiling at last to dissolve the mucus completely. After
a time a white sediment appeared at the bottom of the vessel,
consisting of very minute granular particles. These, when
examined under the microscope, were found to be accumula-
tions of epithelial cells, arranged in a hollow globular form,
and measuring about 1-500th of an inch in diameter. Most
of them were single, and had a small entrance tunnel some-
times opening into a fragment of a larger tube. They re-
sembled very closely a roughly-cast bullet before it has been
trimmed. Here and there others were found in small masses,
like a diminutive bunch of grapes. The rest of the deposit was
made up of amorphous granular membrane, and seemed as if
it had come from a large cayity. I considered that the evi-
dence was scarcely sufficient to enable any decided opinion to
be given; for it was not absolutely certain (however probable
it was) that these casts of cells came from the lungs, and, if
they did, whether they indicated simple inflammation or
tubercular disease. The woman suffered much from relaxa-
tion of the soft palate, and the cells might be from its mucous
glands.

The patient died shortly after, and no examination was
allowed.

The results of this case induced me to examine others of
confirmed phthisis, but in one instance only have I been able
to find a similar appearance. —,The most common phenomenon
is that of a brownish amorphous membrane, of variable size
and shape, studded with oil globules and small nuclei, and
which seems to be the secretion from a diseased surface, and
analogous in a small degree with the amorphous casts found
in chronic desquamative nephritis. As these membraniform
bodies evidently come from large cavities, and have not been
found in those specimens of simple bronchitis that I have
examined, their occurrence in the sputa may probably form a
diagnostic sign between it and phthisis. My observations
have not as yet been sufficiently extended to enable me to
declare positively that they are diagnostic. I would only add,

60 MEMORANDA.

as a sort of apology for my first diagnosis, the following anec-
dote :—A microscopic friend, while examining the sputa of
a phthisical patient, detected in it a number of muscular fibres
exhibiting the striae more beautifully than in any preparation
he had ever seen. After a long consideration of the case and
consultation with another, he came to the conclusion that there
was ulceration of some parts of the larynx with loss of mus-
cular substance. It was not for some time after that he ascer-
tained that the sputa were taken after dinner, that the patient
had had meat, and that the fibres were due to a slaughtered
ox, and not to a human larynx.—T Inman, M.D. Liverpool.

Tue Miscroscore As A Test oF THE Purity or Drinkine
Warers.—In the examination of waters supplied by nature for
dietetical and economical purposes, a chemical examination of
their contents has been usually deemed sufficient in order to
ascertain their qualities. It is, however, evident that, how-
ever accurately chemistry might be able to pronounce on the
quantity of the organic contents of waters, the qualities of
these matters can only be ascertained by means of the Micro-
scope. We are indebted to Dr. Hassall for first takmg up
this subject; and during the last Session of Parliament Dr.
Lankester and Dr. Redfern were examined before the Com-
mittee of the House of Commons, on the water supply of the
Metropolis, with reference to the Microscopic contents of the
Thames and other waters. A report has been drawn up by
these gentlemen at the request of the London (Watford) Spring
Water Company, in which they give the results of their
examination of waters supplied from the Thames, the New
River, the Surrey Sand Springs, the river Dee, and water from
wells at Watford. The mode of proceeding was, to take half
a gallon of the water to be examined, and, after allowing it to
stand for a few hours, to decant the clear liquid from above
till about half an ounce remained. A drop of this was taken
up by a pipette and examined under the Microscope. It would
appear from these reports that, in proportion to the absence of
inorganic and organic matters in a state of decomposition, is the
water free from microscopic plants and animals. Great differ-
ences in these respects are presented by the water examined.
Thus, ia the river Dee and the Watford water, scarcely a
living organism was found, whilst in the Thames and New
River waters above seventy species have been identified by
the reporters.

(ef 5

PROCEEDINGS OF SOCIETIES.

Microscoricat Society oF Lonpon. Session 1852.

January 28.—Dr. Arthur Farre in the Chair. On the structure
of the Raphides of Cactus enneagonus, by Professor Quekett.

February 18.—Anniversary Meeting.

March 17.—George Jackson, Esq., in the Chair. Hints on
the subject of collecting Objects for Microscopical Examination, by
George Shadbolt, Ksq.

April 28.—George Jackson, Esq., in the Chair. On a Cyst,
containing a large crystal of oxalate of lime, found upon the olfac-
tory nerve of a horse, by James B. Simonds, Esq.

May 26.—George Jackson, Esq., in the Chair. On the develop-
ment of Tubularia indivisa, by J. B. Mummery, Esq.

On the structure and development of Volvox globator, by George
Bush, Esq., F.R.S.

June 23.—George Jackson, Esq., in the Chair. On the Anatomy
of Volvox globator, by Professor W. C. Williamson.

British AssOcIATION FOR THE ADVANCEMENT OF SCIENCE.

Belfast Meeting, September 1852.—In the Mathematical Sec-
tion Sir David Brewster gave an account of a Rock Crystal Lens,
which had been found in the treasure-house in the ruins of Nineveh.
The lens was not entirely circular in its aperture, being 1 6-10ths
of an inch in its longer diameter and 1 4-10ths in its shorter.
Its general form was that of a plano-concave lens, the plane side
having been formed of one of the original faces of the six-sided
crystal of quartz. The convex face of the lens was unequally thick,
but its extreme thickness was 2-10ths of an inch, its focal length
being 43 inches. It had twelve remains of cavities, which had
originally contained liquids or condensed gases ; but ten of these
had been opened, probably in the rough handling which it received
in the act of being ground.

Professor Stokes read a paper on the Optical Properties of the
Salt of Quinine, discovered by Dr. Herapath (p. 59). He ex-
plained the remarkable properties possessed by this salt according
to the undulatory theory. ‘The reflecting properties of these crys-
tals, he stated, might be embraced in one by regarding the medium
as not only doubly refracting and doubly absorbing, but doubly
metallic. The principal object of the paper was to point out the
intimate connexion which exists between the coloured reflection,
the double absorption, and the metallic properties of the medium.

In the Natural History Section Professor Allman read a paper on
the signification of the ovigerous vesicles in the Hydroid polyps. He
stated that the structure of these vesicles was the same as that of

62 PROCEEDINGS OF SOCIETIES.

the naked-eyed medusee. From repeated observations, he had come
to the conclusion that the ordinary polypoid structure is not sufficient
for the production of ova, and that for these bodies a medusoid struc-
ture is always necessary, whether it be obvious as in the free gem-
meze, or disguised as in the fixed ovisacs.

The Rey. T. Hincks read a paper, in which he pointed out certain
peculiarities in the structure of some of the marine Bryozoa, which
led him to the conclusion that there existed in these animals a dif-
ference of sex.

Mr. Wyville Thomson read a paper on the specific characters of
some of the Sertularian zoophytes. He endeavoured to point out
the fallacy of using the ovigerous vesicles as means of specific dis-
tinction in this class of animals, and observed that forms of the
same species had been separated by relying on the characters afforded
by these organs.

Professor Allman made a communication on the presence of a
form of fermentation-fungus in the fluid of the warm water flax-
steeps. After the flax has been in the water a few hours, the water,
on being submitted to the microscope, presented numerous minute
granules, which moved about by the aid of a moving cilium.
Sometimes two of these bodies were attached at each end of the
cilium. They ultimately became converted into cells, which pro-
duced smaller cells upon their surface, eventually assuming the
form of a moniliform alga.

Professor Allman likewise described a minute alga, which had
coloured green large masses of water. It was in the form of little
conglomerated gelatinous masses, consisting of numerous fronds.
The fronds were nearly spherical, and consisted of a central mass of
transparent gelatinous matter surrounded by an outer coating of
minute cells of a green colour. The external crust bursts, and allows
the gelatinous nucleus to escape, which then separates into two dis-
tinct fronds by a process of contraction.

A paper was read from Professor Wharton Jones on the forces
by which the circulation of the blood is carried on. In this paper
reference was made to a discovery announced by the author, in a
paper read before the Royal Society on the 5th of February, 1852.
This discovery consists in the fact of a rhythmical contraction ex-
isting in the walls of the veins of the bat’s wing. These veins are
supplied with valves which prevent the regurgitation of the blood ;
and the author suggests that this contractility of the veins is a pro-
vision for securing the return of the blood to the right side of the
heart. The author could not discover this contractility in the ear
of the bat, nor in the mesentery of a mouse.

Fig.

Fig.

DESCRIPTION OF PLATE I.

On Actinophrys Sol, by Professor Kolliker.

1.—Apparent transverse section of Actinophrys Sol, drawn so that the
parts visible in indistinct outline are not indicated. The structure ex-
hibited in this figure is afforded by Actinophrys in any plane passing
through the centre. a, cortex: 6, nucleus of the animalcule; c¢,
homogeneous basal substance ; in the nucleus with numerous granules ;
d, hollow spaces, ‘ Vacuoles,’ filled with a clear fluid; e, tentacular
filaments.

2.—The same, less highly magnified, at the moment of feeding.
a—e as above; f, an Infusorium, which has just entered the sub-
stance of the body, whilst the surrounding filaments enclose it on all
sides ; g, a spore of an Alga already nearly engulphed in the cortical
substance; the depression in which it is contained, however, is still
open to the exterior, the filaments are again nearly erect; h, a spore
of Vaucheria, lying in a hollow space of the nuclear substance.

3.—A somewhat more highly magnified Actinophrys, with very short
just-sprouting tentacular filaments. @«—e,as in fig. 1; f, a Vau-
cheria spore, wholly imbedded in the cortical substance, the opening
through which it entered entirely closed, although its situation is
indicated by a slight depression ; g, another spore, already entering
the nuclear substance; A, an Infusorium lying in a special cavity ;
z, a spore in the nuclear substance; #, half-digested morsels; /, a
swallowed Jynceus; m, excrementitious matter in the form of a
spherical, clear drop, with granules, beginning its exit from the
cortical substance. A portion of it is already protruded from an
opening, the margin of which is fringed.

. 4,—A smaller portion of the border of an Actinophrys, magnified 450

diameters. a,c, d,e, as in fig. 1; /, sprouting, conical, tentacular
filaments; g, one a little longer; A, enlargement upon a developed
but not extended filament.

. 5.—A portion of the nuclear substance, magnified to the same extent.

c, d, e, as before; f, nucleus in one of the hollow spaces; g, a cell ?
from another hollow space, isolated.

. 6.—A true anastomosis of three striped muscular fasciculi from the

auricle of the frog. «a, sarcolemma; 3, fibrille, with transverse
stripes.

On the Contractile Tissue of the Iris, by Joseph Lister, Esq.

Figs. 7, 8, 9, 10, 11. Muscular fibre-cells of the human iris.

Fig.

12.—Nucleus from the sphincter pupille of a horse.
13.—Muscular fibre-cells from the edge of the pupillary margin of the
iris.

64

DESCRIPTION OF PLATE I.

Anatomy of Melicerta ringens, by Professor Williamson.

Fig. 14.—Animal of Melicerta ringens removed from its case.

15.—One of the tentacles (Fig. 14 d) fully expanded.

16.—The same, with the sete drawn inwards.

17.—Dental apparatus (Fig. 14 e) more fully magnified.

18.—One of the ciliated epithelial cells from the upper stomach.
19.—Lower part of the visceral cavity, and upper part of the caudal
prolongation, more fully magnified.

20.—Extremity of the caudal prolongation expanded into a dise.
21.—Muscular fasciculi, invested with their sarcolemma in a state of
corrugation.

22.—Ditto, with the sarcolemma stretched out.

23.—One of the nuclei of the ovary with its nucleolus.

24.—The nucleus, as removed from a fully-formed ovum. The nu-
cleolus absorbed.

25, 26, 27, 28, 29. Ova in various states of development.

30. The animal of Fig. 29 just liberated from the ovum.

31.—The same animal in motion.

32, The young animal affixed to a leaf, and commencing the con-
struction of its external case,

33.—Portion of the case at its lower extremity.

34.—The same at its upper extremity.

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BRACHIONUS.

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A WAG iIMUiARLA. B MELICEHRTA.

DESCRIPTION OF THE PLATES.

The letters throughout have the same signification :—a, trochal dise ;

b, body ; ¢, tail of peduncle; d, mouth; e, pharynx; /, ‘‘ yellow mass ;”

9g, gizzard; h, “pancreatic sacs ;” z, rectum; k, anus; /, ovary; m,

_water-vessels ; 7, ganglion; 0, ciliated sac; p, upper circlet of cilia; p’,
lower circlet of cilia; 7, vacuolar thickenings.

PLATE I.—Lacinularia socialis.

. 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. x

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

19. Spermatozoon ?

OONABAMPROD EE

PLATE I.

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, D.

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.
86. From the mouth side.
37. From the ganglionic side.

PLATE III.

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

= Iran Note V3 Se ea LLL

‘Ditton Wert, scalp Teed & West Imp 54 Hattce Garden

ORIGINAL COMMUNICATIONS.

On the Anatomy of Me.icerta RINGENS. By Professor
W. C. Wittramson.

[Continued from page 8.]

The most interesting portion of the history of Melicerta is
connected with the development of its ova, which process the
transparency of its organs enables us to watch with facility.
I have already described the position of the ovary and oviduct.
The ovary is a hollow sac consisting of a very thin pellucid
membrane. It is filled with a viscid granular protoplasm of
a light grey colour, in which are distributed from twenty to
thirty nuclei (23), each having a diameter of from 1-1200th
to 1-1600th of an inch. Each nucleus contains a large nu-
cleolus varying in diameter from 1-1600th to 1-3500th. In
its normal state, the granular protoplasm is of an uniform grey
colour, flowing freely out of the ovary when the latter is rup-
tured. The nuclei situated near the centre of the ovary appear
to be successively selected for development. One of these nearest
the surface attracts round it a small portion of the granular pro-
toplasm, detaching it from the remaining contents of the organ,
though still in close contact with them. The portion thus
specially isolated gradually enlarges, assuming at the same time
a darker hue, whilst, from its central position, it partially divides
the upper from the lower half of the remaining ovarian proto-
plasm. At the same time the central nucleus sometimes
undergoes some slight enlargement, and its nucleolus appears
to become absorbed ; the position of this nucleus in the centre
of the ovum is now indicated by an ill-defined transparent
spot; but on bursting the protoplasmic mass it is seen to be
a small spherical cell (26) about 1-1000th of an inch im
diameter, having very thin pellucid walls, and scarcely any
visible cell-contents. When the ovum thus segmented from
the ovarian protoplasm has attained its full size (14 ¢q), it
becomes invested by a thin shell, which is apparently a secre-
tion from its own surface. This view of its origin is of course
difficult to prove, but I have sought in vain for evidence that
it could have been formed in any other way.

The ovum being now ready for expulsion, it is slowly forced
down to the lower part of the ovary, the stomachs being drawn
upwards and to one side in order to make way for it. Yield-
ing to the pressure produced by the successive contractions of
the body, the ovum sweeps round the inferior border of the

VOL. I. F

66. ON THE ANATOMY OF MELICERTA RINGENS.

lower stomach, and, passing through the dilated oviduct, enters
the cloaca. ‘The latter canal becomes entirely everted, as is
the case when the excrements are discharged, and by a sudden
contraction the ovum is expelled.

At this stage of its development the egg has an average
length of 1-150th of an inch, and a diameter of 1-250th. Its
yolk usually consists of a single segment (14 q and 25), there
being a small space at each extremity of the egg which the yolk
does not occupy. Very soon, the central nucleus becomes drawn
out and subdivides into two, this division being followed by
a corresponding segmentation of the yolk (26). The same
process is repeated again and again (27), until at length the
entire yolk is conyerted into a mass of minute cells (28).
The first trace of further organization which presents itself
appears in the form of a few freely moving ciliz. These pre-
sent themselves at two points, one at 28 a, which corresponds
with the future head, and the other near the centre of the
ovum (286), which is destined to become the cavity of the
stomach: shortly after this appearance of cilia, traces of the
central parts of the dental apparatus present themselves, this
again being soon succeeded by the union of the entire mass of
yolk-cells, and the formation from them of the various organs of
the animal (29). The ciliz now play very freely, especially
at the head (29 a). The creature twists itself about in its
shell; two red spots (29 6) appear near the head, which
Ehrenberg regards as organs of vision, and along with them a
very dark brown and somewhat larger spot is developed in the
integument near the lower stomach. The young animal now
bursts its shell, and, on first emerging, presents the appear-
ance of fig. 30; the two hooks are formed (30 a) as well as
rudiments of the two tentacles (30 5), and the whole of its
internal organization, though but obscurely seen, is neverthe-
less that of the perfect animal, and not that of a larval state.

Almost immediately after its escape from the egg, the
young Melicerta stretches itself out, and everting the anterior
part of its body unfolds several small projecting mamillz
covered with large ciliz, by means of which it floats freely
away. Its present form is seen in fig, 3l. The ciliated
mamille (31a) at this stage of growth are not unlike those
seen in Notammataclavulata, but they soon enlarge and become
developed into the flabelliform wheel-organs of the matured
animal. The dental apparatus (31 0) is now fully developed ;
the alimentary canal and muscular fasciculi are all present,
only the epithelial cells of the former have not as yet ob-
tained their yellow granular contents, consequently the viscera
exhibit the same hyaline aspect as the rest of the organism.

ON THE ANATOMY OF MELICERTA RINGENS. 67

The two red specks (3i ¢) are imbedded in two of the
mammille.

After swimming about for some time, like other free Roti-
fera, the animal undergoes further changes. The dark brown
spot (31d) is the first to disappear, and soon afterwards the
two pink ones (31 ¢) cease to be visible. The animal attaches
itself by the tail to some fixed support, and developes from
the skin of the posterior portion of its body a thin hyaline
cylinder, the dilated extremity of which is attached to the
supporting object. This structure has been already noticed
by Dr. Mantell (Thoughts on Animalcules), though I have
never seen it so largely developed as is represented in his
figures. The young animal, having chosen a permanent rest-
ing-place, commiences the formation of its singular investing
case. I have verified Dr. Mantell’s account of the position
occupied by the first-formed spheres. They are arranged
in a ring round the middle of the body, and are for some
time unattached to the leaf or stem which supports the
animal. They appear to have some internal connection
with the thin membraneous cylinder (32a). At first, new
additions are made to both extremities of the enlarging ring.
But the jerking contractions of the animal at length force
the caudal end of the cylinder down upon the leaf, to which
it becomes securely cemented by the same viscous secretion
as causes the little spheres to cohere. All the new additions
are now made to the free extremity, which, as Ehrenberg
remarks, never extends beyond the level of the cloacal aper-
ture of the outstretched animal. At its attached base, the
cylinder consists of closely fitting hexagons (33) 1-1600th
of an inch in diameter; but as we approach the opposite
extremity, they become perfect spheres (34) (1-1100th of
an inch in diameter), each one touching six surrounding ones,
by six corresponding peripheral points. Small triangular
spaces intervene, occupied only by the transparent secretion
which glues the little spheres together. The fully-matured
animal maintains its position within this case by means of its
caudal prolongation, the extremity of which can be more or
less flattened out into a suctorial dise (20 c).

From the above description it will be seen that the Melicerta
ringens, one of the most highly organised of the Rotifera, does
not pass through any larval form, in which it is represented
by some of the simpler polygastric Infusoria. Though its
external appendages, and especially the rotatory organs, are
imperfectly developed at its birth, the organization as a whole
is complete and final. The parts are all present, and only

require to be expanded by the ordinary process of growth.
F 2

68 ON THE ANATOMY OF MELICERTA RINGENS.

We have no metamorphosis such as is common amongst the
Articulata: I have not even seen any evidence that the creature
casts its skin. This fact was noticed by Dutrochet, and his
observation appears to be correct.

When the ova are discharged from the cloaca they succes-
sively fall into the cavity of the tessellated case, where they
undergo their further development. I have often found as
many as four in one case, in the various stages of progress
represented by figs. 12 to 16. It is whilst the eggs are thus
protected that the young animals burst their shells—swim-
ming out at the free extremity of the case as soon as they are
liberated. When the ovum escapes from the cloaca its yolk
usually consists of a single segment. In one insiance only it
had divided into eight whilst within the ovary. A second
ovum is frequently seen progressing towards development
whilst a fully shelled one is retained in the ovarium. Re-
specting the process of fertilization we know nothing. The
two tubes which I have referred to as being possibly spermatic
ducts are the homologues of similar ones in other Rotifera, to
which Ehrenberg has assigned fertilizing functions. Melh-
certa ringens countenances his opinion on this point, though it
does not prove it. I have seen nothing resembling spermatozoa.

In the possession of so highly organised a form of voluntary
muscle, in the investment of the faseiculi by a sarcolemma, and
in the existence of a well defined ciliated cellular epithelium
lining the alimentary canal, we have indications of an organiza-
tion approaching that of the lower Articulata. The dental
apparatus appears to constitute a splanchno-skeleton like that
of the Crustacea; but, on the other hand, the absence of a
visible nervous system removes the Melicert@ far below the
Homogangliate animals. That they should possess a nervous
system of some kind appears almost a matter of necessity, if
the presence of striated muscular fibre indicates volition ; but
its actual existence has yet to be demonstrated.

I have found no special organs of circulation or respiration.
On watching the movements of the small free cells which float
in the visceral cavity, as well as in the tail (147), it becomes
obvious that the fluid contained within the integument moves
freely with every contraction of the body. I detect no vessels
or pulsating organs. ‘These facts also tend to associate the
animal with the lower Nematoneura, if not even with the
Acrita, rather than with the Homogangliate Crustaceans. At
the same time its organization is of a higher type than that of
the Bryozoa.

Any attempt to establish the existence of homologies between
the phenomena attending the development of the ova in the

ON THE ANATOMY OF MELICERTA RINGENS, 69

Melicerta and those of the higher Mammalia may be deemed
premature and unwise. Nevertheless there are some points
in which a close relationship appears to be displayed. ‘These
affinities will be best traced by proceeding backwards from a
stand-point where the homology is clear and definite. The
yolk of the matured egg of Melicerta is the obvious homologue
of the yolk of the Mammalian ovum. The circumstance that
the entire yolk of the former enters directly into the composi-
tion of the young embryo, by a process of segmentation, instead
of indirectly and through the medium of a germinal membrane,
does not materially affect the case. The granular yolk of the
Melicerta still corresponds with some early states of the granular
yolk of the Mammalian ovum. In the latter case each Graafian
vesicle is filled with granules, along with some nuclei, float-
ing in a colourless fluid. Amidst these, the germinal vesicle,
with its. contained nucleus or germinal spot, is developed.
After a while some of the granules and a portion of the fluid
in which they float are attracted around the germinal vesicle,
and thus form the yolk, All this corresponds with what takes
place in Melicerta. The entire sac of the ovary in the latter
resembles a large compound Graafian vesicle distended with
fluid, in which there float numerous granules, as well as
twenty or thirty nucleolated vesicles, or nuclei ; each of these
nuclei successively attracts around itself a portion of the gra-
nular fluid to form the granular yolk, and the thickened shell
may perhaps be regarded as the vitelline membrane, though
this latter idea is not free from some objections. Bischoff has
observed that, as the Mammalian ovum advances towards ma-
turity, the number of the granules increases, and hence the
yolk is more opaque in the mature, and more transparent in
the immature ovum. This is precisely identical with the
changes undergone by the yolk of the Melicerta, as described
in the preceding pages. We may conclude from this com-
parison, that the elements which are contained in and solely
occupy the ovisac of the Melicerta, are those which in the
ovaries of the higher mammalia are restricted to the interiors
of the Graafian vesicles; that whilst in the former case the
protoplasmic stock forms one undivided mass, from which
portions are successively pinched off to form the ova, in the
latter examples it is divided into small portions, each being
contained within a special receptacle, or Graafian vesicle ; the
interspaces being occupied by the stroma or tissue of the
ovary.

Since recording the preceding observations, I have had the
advantage of perusing Mr. Huxley’s instructive paper on

70 ON THE ANATOMY OF MELICERTA RINGENS.

Lacinularia. 1 have verified Mr. Huxley’s observation of
the existence of two circlets of cilia, fringing the double mar-,
gins of the sinuated wheel-organs ; one being larger than the
other. The larger one passes round the fissure dividing the two
larger lobes, and consequently above the mouth. The smaller
one, which is most external, passes below the mouth, being con-
tinuous with the ciliz which fringe the “chin” of Mr. Gosse,
the “ fifth wheel-organ” of the preceding memoir. The food
that reaches the mouth is whirled round the wheel-organs
along the groove that separates the two circlets of cilia; and
since these circlets diverge near the “ chin,” the mouth being
located between them, the food is necessarily conveyed di-
rectly to the latter organ. The two sets of marginal cilia,
by bending towards each other whilst in motion, almost con-
vert this groove into a sinus, especially in the two larger
segments. I had previously noticed the outline formed by
the outer and smaller of these margins, but regarded it as
merely a thickened portion of the disk, to the surface of
which I erroneously imagined these additional cilia to be
attached. On each side of the oral aperture there project two
small flattened lobes with ciliated margins, continuous with
those of the chin, and which obviously assist in directing the
food into the cesophagus.

Between the mouth and the cesophageal bulb, on the same
side as the ovary, is the transparent ball of horn-like sub-
stance referred to by Mr. Huxley ; within the cesophagus, near
its junction with the pharyngeal bulb, the ciliated lining mem-
brane appears to hang in several loose, vibratile, longitudinal
folds. I do not feel satisfied respecting the functions of the
‘“‘ nervous ganglion” of Mr. Huxley. I see no sufficient rea-
sons for assigning to the small organ in question nervous
functions. * Of the ciliated sac of Mr. Gosse I have obtained
some faint glimpses, not having been so fortunate as to see
the animal when engaged in its architectural occupations ; when
not so engaged the sac becomes so contracted as to be almost
invisible,

The singular bodies resembling spermatozoa exist in various
parts of the organism, where they are apparently enclosed
within hollow canals, I have never seen them occupying the
two main trunks of the “ water vascular system,” or czeca, nor
can I succeed in tracing any connexion between them. In
several cases | have seen one or two of these curious bodies
opposite the centre of the upper stomach, very near to, but
independent of, the main caecal canal, and at some distance
below the point where the latter probably subdivides into
branches. Near the neck there are usually from two to three

GOSSE ON THE MELICERTA RINGENS, 71

pairs. Their vibratile motion ceases the moment the animal
is killed by pressure. This fact does not countenance the
idea that they are spermatozoa.

Two or three pyriform glandular (?) looking bodies are
often attached to the base of the upper stomach, near the con-
striction which separates it from the lower one. Similar but
larger bodies are seen in the neighbourhood of the cesophagus.
Not having been able to trace any ducts or orifices passing
from these organs to the viscera, | have hesitated to assert
their glandular character.

In one example of Melicerta, the membranous ovisac was
contracted and empty, containing neither protoplasm nor nuclei.
Is this accidental, or may it have been a male animal ?

On the Structure, Functions, Habits, and Development of
Meticerta R1InGENS. By P. H. Gossz, A.LS.

By the courtesy of Mr. Matthew Marshall I was favoured, on
the 27th of May, 1851, with some fragments of Lemna trisulca,
and other aquatic weeds, from a large glass jar, swarming
with Melicerta to such an extent that sixty or seventy are
crowded on a single leaf. They are very distinctly ap-
preciable to the naked eye, for many of the tubes are 1-24th
of an inch long, and when the animals are expanded, they
reach to about 1-20th of an inch. They are set on both
surfaces of the leaves. The tubes contain about thirty-two
rows of pellets; each pellet is surrounded by six others ;
the rows are straight and uninterrupted perpendicularly, but
transversely they are zigzagged, and the regular course is dia-
gonal, Each pellet, examined separately, is of a yellowish or
olive colour, composed of granules, and rather oval than round:
the whole tube is of a reddish-brown. In old ones the surface
is studded with Conferve, Diatomacee, Podophrye, and other
extraneous matters, even to the summit. By picking to pieces
the tube with the points of needles under a small microscope,
I can readily extract the animal; it is often hurt by the pro-
cess, but generally it is sufficiently whole to display the organ-
ization. Fig. 12, plate I1., is one so extracted. The tubes or
spurs on each side of the head below the chin are evidently
consimilar with the antenne of Rotifer, &c. There is a slender
piston in each, capable of being retracted and protruded, and
bearing at its extremity a tuft of very fine, divergent, motion-
less hairs.

The jaws are very complex, and differ so much in different
aspects, that they are difficult to understand. Viewed in situ

72 GOSSE ON THE MELICERTA RINGENS.

their appearance is as at fig. 16, or that of a single one examined
carefully, as at fig. 17; but, under pressure, they become turned
half-round, and appear as at figs. 18 and 19. In figs. 20 and
21 these two aspects are reconciled, the corresponding parts
being lettered alike, according to my belief. The oblique pro-
jection (d) appears conspicuous in a side view, as shown 7x
situ in fig. 20. These parts are enclosed each in a globose
transparent muscle (?), by whose action the form is much al-
tered ; the points of the teeth (a) are drawn forward and down-
ward, or vice versa, and the part (6) seems to be lengthened and
variously modified in form, “A filmy line, more or less obvious,
connects the point b (in fig. 20) with its fellow in the opposite
jaw in some unintelligible way (sce fig. 16), The action is not
exactly that of two flat-surfaced mullers working on each other
in a grinding manner, but a complex motion, impossible to
be explained by words. Below the two globose lobes there is
another rounded lobe (see figs. 16 and 18) equally hyaline, and
probably muscular, which seems united to the two others, and
alters in form as they and the jaws work, lengthening down-
ward as they approach, and dilating and shortening as they re-
cede. A slender cesophagus leads down to the gizzard, through
whose lower part water is continually percolating, as it appears ;
but perhaps the appearance is caused by ciliary waves. Below
the gizzard extends along, wide cylindrical stomach ; it ap-
parently embraces the gizzard at its base without an appre-
ciable tube ; a large globose gland (see fig. 12) 1s probably one
of a pair of pancreatic glands. ‘The walls of the stomach are
tnick, and the food is received into a central tube, whence it
passes into a globose intestine, the interior of which is covered
with minute cilia, From the lower part of this viscus a slender
but dilatable rectum turns up, and proceeds forward toward
the occiput, till it terminates on the dorsal surface, just below
the level of the gizzard. The cloacal outlet is capable of being
greatly protruded, and this takes place in the moment of dis-
charge, in order to shoot the faecal mass out of the case, for it
is then projected from above therim, The feces are slightly
coherent and jelly-like, not at all like the case-pellets. The
ventral region is, as usual, occupied by the ovary, sometimes
granular and clear, at others filled with a dark maturing ovum.
The head-mass, when retracted as in fig. 12, appeared separate
and removed from the outer integument, and to be drawn
together in a puckered manner. It descends into a small
conical tubercle behind the gizzard, and between this and the
base of the stomach there was one little tremulous tag, of the
same structure as in Notommata aurita. From the same spot
also project, into a space of peculiar clearness, two trumpet-

GOSSE ON THE MELICERTA RINGENS. 73

shaped bodies of the greatest delicacy, and without motion
(See fig. 12).

From far up in the trunk long muscular cords descend and
pass into the foot, which they entirely traverse. This long
organ is corrugated into close, irregular, transverse wrinkles;
and there seem to be annular muscle-rings, exceedingly numer-
ous throughout. The tip of the foot is not cleft, but it has a
retractile disc, doubtless a sucker, if this be the principle of
its adhesion; but near the tip, on its ventral side, there ap-
peared a little granular body connected with the tip by a point,
and enlarging at the upper end, where it was connected with a
small globular vesicle. (See fig. 22.) Can this be a secerning
gland for the secretion of an adhesive glue, by which the foot
adheres, as in Monocerca ?

Opening one or two cases I freed one and another very
curious egg-like bodies (fig. 23), not symmetrical in shape,
being oaks more gibbous on one side than the opposite, and
measuring 1-150th by 1-260th of an inch, Each was encircled
by five or six raised ribs, running parallel to each other longi-
tudinally, somewhat like the varices of a Wentle-trap. Viewed
perpendicularly to the ribs the form is symmetrical—a long,
narrow oval. The whole surface between the ribs appeared
punctured or granulate, and the colour was a dull brownish
yellow. Under pressure it was ruptured, and discharged an
infinity of atoms of an excessive minuteness, but every one of
which, for a few seconds, displayed spontaneous motion.
Their whole appearance, and the manner in which they pre-
sently turned to motionless disks, were exactly the same as of
the Spermatozoa, which the male eggs of other Rotifera con-
tain, except that these were so minute.

From another I extracted an egg of the ordinary form and
appearance (fig. 24). It was very long, measuring 1-145th by
1-390th of an inch. The contained embr yo was well advanced ;
two red eyes were plainly seen by reflected and by transmitted
light: the gizzard was transverse, very large in proportion,
and the jaws worked vigorously ; a little opaque body, white
under sunlight, was in the posterior part. This embryo died
without hatching.

May 30.—A young one, about half adult size, was at-
tached by the base of its tube to the side of the tube of an
adult, near the summit of the latter, so as to project obliquely
upward. This specimen, which was perfectly formed, gave
me an excellent opportunity for observing the ventral aspect
(see fig. 14), and the dorsal (fig. 15). It had two red eyes, one
placed. near the base of each larger petal. I could not discern
eyes in adults. It was very energetic, diligently engaged in

74 GOSSE ON THE MELICERTA RINGENS.

manufacturing the pellets and laying them on. It seems that
the action of the pellet-cup is voluntary, and not always co-
existent with the passing of the ciliary current over the chin,
The animal frequently makes abortive efforts to deposit a
pellet, and sometimes bends forcibly forward to the edge of
the case before the pellet is haif formed. The chin forms a
projecting lobe, apparently concave at the tip, spoon-shaped
or tubular (see fig. 13), well covered with cilia, which carry on
the current from the great sinus. The petals are evidently
thick in the middle, and I think are very abruptly attenuated
from the ring of nervous (?) matter that runs round them, to
the margin. The wheel-cilia have their bases on this ring,
and not on the margin (see fig. 15); a very delicate granular
mass runs out in a point from the base to the centre of each
petal; this may be cerebral, and the rings muscular. The
edges of the petals are contracted, corrugated, incurved, and
folded together at the will of the animal. Between the two
larger petals is the mouth, for in the lateral view (fig. 13)
a rather wide pharynx was distinctly seen extending from
that point to the summit of the gizzard, and minute particles
were traceable through it, which were rapidly poured be-
tween the jaws. The lower portion of this duct is seen also
in fig. 14. The breast, between the diverging antenne, forms
several irregular rounded lobes, and below the gizzard it is
constricted laterally.

There is a very close affinity between Melicerta and the
Philodinade, say, for example, Rotifer citrinus. ‘The wheels
are sinuous instead of round, but the great sinus and pro-
jecting spoon-shaped chin are in both; the antenna, single
and medial in MRotifer, is repeated and thrown apart in
Melicerta, but the structure is identical: The gizzard is
essentially the same—a pair of muscular hemispheres with
hard transverse teeth: tbe stomach and intestine are the
same; and the upward direction and production of the rec-
tum are but trivial modifications dependent on a tubicolous
habit. The structure of the foot is, however, nearer to that
of Brachionus, or perhaps Pterodina, being corrugated, not
telescopic-jointed, and terminating in a sucker, not in toes ;
but this again is a tubicolous modification.

May 31.—On looking into the live-box, in which were
several tubes, I found a young one swimming rapidly out in a
giddy, headlong manner. I believe it was just hatched. Its
form was somewhat trumpet-shaped, or like that of a Stentor,
with a wreath. of cilia around the head, interrupted at two
opposite points. ‘lhe central portion of the head rose into a
low cone. After whirling about for a few minutes, its motion

GOSSE ON THE MELICERTA RINGENS. 75

became retarded, and it began to adhere momentarily, and to
move forward by successive jerks, not more than its own
length at once. The periods of its remaining stationary in-
creased, so that I several times supposed it had taken up its
permanent position, when some shock or alarm would send it
off for a little distance again. At length, about an hour after I
first saw it, it finally settled, adhering by the foot to the lower
glass of the box. Fig. 25 represents the ventral, fig. 26 the
dorsal outline of this young one, but more I could not sketch,
for after a few rapid gyrations upon the foot as a pivot, it
became vertical, and appeared to the eye looking down on it,
as at fig. 27. The form of the adult was now distinctly
assumed, the four petals of the disk were well made out,
though the sinuosities were yet shallow: the antenne at first
were only small square nipples (fig. 27, aa), but soon shot
out into the usual form; the ciliated chin was distinct, as was
also the whirling of the pellet-cup immediately beneath it.
A pellet was quickly formed, and instantly deposited at the
foot; the same operation was repeated with energy and in-
dustry, so that in a few minutes a row of pellets were seen,
forming a portion of a circle around its foot-base, as shown
at fig. 27,5. When two or three rows were formed, I took
occasion to measure the time of their construction; one pellet
was deposited every minute with great regularity. 1 mixed a
little carmine with the water: the result was beautiful; for
the dark torrent that poured off in front, and the appearance
of a rich crimson pellet in the cup (fig. 27, ¢), were instanta-
neous. Yet the imbibition seemed deleterious; for the
animal would withdraw itself suddenly, after a revolution or
two, and presently retired sullenly, having laid five or six
carmine pellets, whose deep tints made them conspicuous on
the pellucid yellowish ones. Some three hours after, I saw
that no more were laid. But in the course of the night the
case was considerably increased with carmine; the part so
made was much less regularly formed of pellets than that
composed of the natural material, for the red portion was all
confused and blended as it were into a mass, without distinc-
tion of pellets, though retaining the tubular form.

A large one, whose case had become accidentally injured
near the base, so as to be slit for some distance up, protruded
itself through the opening, remaining still attached by the
foot. It did not again enter, but continued for several days,
carrying on all its functions in the healthiest manner, exposed.
‘It frequently made pellets, but these were never deposited,
but allowed to wash off into the water, nor was any attempt
made to construct a new case. A half-grown one, very active,

76 ON THE CORNEA OF THE EYE IN INSECTS.

that was near, deposited pellets only rarely, eight .or ten in
several days; whence it appears that this process is quite
voluntary : indeed, if it were not so, so rapid is the formation,
that the tube would be increased beyond all bounds in a very
brief period of the animal’s life.

The process of swallowing carmine enabled me to see very
distinctly that (as shown at fig. 14) the cesophagus enters the
gizzard between the larger ends of the jaw-mullers, and that
the stomach-duct leads off from their smaller ends, through
the semi-globular Jobe beneath. This duct, though short and
wide, is distinct.

June 12.—The young one obtained May 30 was active
till this morming, when it suddenly died, having lived ur
confinement fourteen days. During the whole time it has
scarcely increased in size, nor has it added any pellets to its
case, except a few the first day or two. The eyes were dis-
tinctly visible to the last.

Remark on the Cornea of the Eye in Insects, with reference to
certain sources of fallacy in the ordinary mode of computing
the Microscopie hexagonal Facets of this membrane: with an
Appendix, containing a brief notice of a new method of taking
transparent Casts of the above, and other oljects for the
Microscope, in Collodion. By Joun Gornam, M.R.CS.L.,
Fellow of the Physical Society of Guy’s Hospital ; Honorary
Fellow of the Royal Botanic Society of London, ce.

Tue eye of the Insect tribe has been chosen for the present
communication, not only from its great beauty and wonderful
organization, but on account of its transparent portion (cornea)
presenting a multitude of well-defined planes, forming a reti-
culation which is especially calculated to excite our admira-
tion. It is to this, therefore, and not to the interior, that our
attention will be chiefly directed.

On examining the head of an insect we shall find a couple
of protuberances more or less prominent, and situated symme-
trically, one on each side. Their outline at the base is for
the most part circular, elliptical, oval, or truncated; while
their curved surfaces are spherical, spheroidal, pyriform, &c.

These horny, rounded, naked parts seem externally to repre-
sent the corne of the eyes of Insects; at least they are ap-
propriately so called from the analogy they bear to those trans-
parent tunics in the higher classes of animals. They differ
from these latter, however, in this respect, that, when viewed
by the microscope, they display a number of hexagonal facets

ON THE CORNEA OF THE EYE IN INSECTS. 77

which constitute the media for the ingress of light to as many
simple eyes. Under an ordinary lens, and by reflected light,
the entire surface of one of these cornex presents a beautiful
reticulation, like very fine wire gauze, with a minute papilla, or,
at least, slight elevation in the centre of each mesh. These
are resolved, however, by the aid of a compound microscope,
and with a power of from 80 to 100 diameters, into an almost
incredible number, when compared with the space they
occupy, of minute, regular geometrical hexagons, well-
defined and capable ot being computed with comparative
ease, their exceeding mipateness being taken into considera-
tion. When viewed in this way (hau entire surface bears a
resemblance to that which might easily and artificially be
produced by straining a portion of Brussels lace with hexa-
gonal meshes over a Saal hemisphere of ground glass. That
this giv es a tolerably fair idea of the intricate carving on the
exterior may be further shown from the fact that delicate and
beautiful casts in collodion* may be procured from the sur-
face by giving this three or four coats with a camel’s-hair
pencil. When dry it is peeled off in thin fla!.es, upon which
the impressions are left so distinct, that their hexagonal form
can be discovered with a Coddington lens. This experiment
will be found useful in examining the configuration of the
facets of the hard and unyielding eyes of many of the Coleo-
ptera, in which the reticulations become either distorted by
corrugation or broken from the pressure required to flatten
them. It will be observed, also, that by this method perfect
casts of portions of the cornea can be obtained without any
dissection whatever, and that these artificial exuvia, for such
they really are, become available for microscopic investi-
gations ; obviating the necessity for a more lengthened or labo-
rious preparation.

But to return. The dissection of the cornea of an insect’s
eye is by no means easy. I have generally used a small pair
of scissors, with well-adjusted and pointed extremities, and a
camel’s-hair pencil, having a portion of the hairs cut off at
the end, which is thereby flattened. The extremity of the
cedar handle, on the other hand, is shaved to a fine point, so
that the brush may be the more easily revolved between the
finger and thumb, and the coloured pigment on the inte-
rior may thus be scrubbed off by this simple process. A brush
thus prepared and slightly moistened forms, as far as my ex-
perience goes, by far the best forceps for manipulating these
objects preparatory to mounting ; as, if only touched with any

* A solution of gun-cotton in chloroform, It can be procured of any
chemist.

738 ON THE CORNEA OF THE EYE IN INSECTS.

hard-pointed substance, they will often spring from the table
from mere elasticity, and thus the labour of hours may be lost
in one single moment. It does not appear to me desirable to
attempt to flatten an entire cornea by pressure and maceration,
although I am aware this is generally recommended, but no
useful purpose is really served either in developing the
beauty or counting the number of its lenses. The rounded
membrane, on the other hand, becomes, as might be antici-
pated if the margin remains intact, corrugated, and so one
hexagon overlaps the other. It will be useful, therefore, to
make two preparations of the eyes of one insect, the one
entire, retaining its naturally curved form, not having been
subjected to any pressure—the other nicked at its margin, or
cut into small fragments and pressed flat between two slides.

Each of the hexagons above-mentioned is itself the slightly
‘“‘ convex horny case of an eye. Their margins of separation
are often thickly set with hair, as in the Bee; in other in-
stances they are naked, as in the Dragon-fly, House-fly, Ke.
The number of these lenses has been calculated by various
authors, and their almost incredible multitude has very justly
excited astonishment. Hooke counted 7000 in the eye of a
House-fly ; Leeuwenhoek more than 12,000 in the eye of a
Dragon-fly, and 4000 in the eye of a domestic fly; and
Geoffroy cites a calculation, according to which there are
34,650 of such facets in the eye of a Butterfly.”

Having carefully examined with the microscope a small
flattened portion of the eye of a Dragon-fly and a few analo-
gous specimens, we are, I think, in a position to assume two
things which will serve to form the basis in our calcula-
tions :—

lst. That the reticulations referred to are composed of per-
fect, regular, geometric hexagons; and

2ndly. That the hexagons are all of equal size.

Their number, in any individual specimen under investiga-
tion, might, of course, be ascertained by actual enumeration ;
the process however would be a very laborious one, and in-
jurious to the sight. Leeuwenhoek computed them by assum-
ing the prominent part of the eye to be hemispherical.* He
then counted a single row of hexagons from the summit to
the base, and this multiplied by four gave the great circle
of a sphere, the area of which was then discovered by a
simple arithmetical process. It will be observed, however,
that those eyes only, the surface of whose common cornea is
hemispherical (and there is a large number in which it is
not), can be treated in this way; and, if the facets could be

* The eye under examination was that of the Moth of the Silk-worm.

ON THE CORNEA OF THE EYE IN INSECTS. 79

thus computed, the results would be incorrect according to the
method of Leeuwenhoek ; inasmuch as in all his calculations

the hexagons were reckoned as squares: thus many hundred
were lost even in one single eye. Having pointed out this
source of fallacy, we proceed to endeavour to correct it.

A mere inspection of the above square area of hexagons
will show that such an outline, enclosing as many regular
hexagons of a given size as it will contain, has a less number
on the one side, A B, than on its adjacent side, AC. A
closer examination will discover that these numbers bear a
ratio of 8: 9.25, or of 1: 1.156; while, if the entire area
is counted, not omitting the portions which are truncated by
the sides of the square, it will be found about 74 (or 8 x
9.25). Those numbers are not, indeed, mathematically cor-
rect, but sufficiently so for our present purpose ; for, doubt-
less, we have not failed to notice that if the side, A B, had
been squared in the ordinary way (8 x 8), and not treated as
if it were composed of hexagons (8 x 9.25), we should have
lost as many as ten planes even in a space containing so few
hexagons ; and these will vanish by hundreds instead of tens,
as the area increases.

And, if we take a circle with a row of hexagons passing
through its great diameter, A B, and calculate from this the
entire number spread over its whole superficies, we shall soon
discover how very far wide of the truth our results would be,
supposing the hexagons were treated as squares. For, first,
let it be required to find the area of a circle in squares with
any number, say twenty, composing its diameter. Now, the

80 ON THE CORNEA OF THE EYE IN INSECTS.

square of the diameter X .7854 = the area: hence 20° x .7854
= 314.160 the area in squares.

Again, given a circle whose diameter = 20 regular hexa-
gons, arranged with their sides in apposition (fig. 1), to find
the area in hexagons. Now, as circles are to one another as
the squares of their diameters, and as we have already seen
that a square of hexagons = the product of 8: 9.25, or
numbers in that ratio, we have :—8: 9.25 :: 20: 23.125.
Hence 20 x 23.125 = 462.5, the diameter squared, and 462.5
x 7854 = 363.247 the area in hexagons.

Or a circular area of hexagons may be thus found :—

Given: a circle with twenty small hexagons (arranged side
by side, fig. 1) passing through its great diameter, to find the
area,

The circle of the circumscribing circle will pass so close to
the side C D (fig. 2) of the hexagon, that we may safely call

ON THE CORNEA OF THE EYE IN INSECTS. 8]

1 irc
EB= of the diameter. Now evidently Fee a gh has —

20 area of hexagon
number of hexagons; we have therefore to find area of hex-
agon.

BC =AC-—AB =4BC?— AB
3BC = AB
2 AB
co ia.
AB

area of triangle ABC = BC x AB = Wa

1
a (=?) ‘=
1
5 D?v/3 = 00125. D# 1.73025

800
area of circle = .7854 D? = .0021650625 D?
£7854.

area of circle
= no. of hexagons = 002165 = 363 nearly.

2
= 2 A B* ./3

area of hexagon = 6 V3

area of hexagon

From these and analogous calculations, tables might be
constructed for all possible dimensions of the square and the
circle, the side being given in the former case, and the
diameter in the latter :—

SQUARE.
Side. _ Area Saree Difference.
in Squares. | in Hexagons.
10 100 115 .625 15.625
20 400 462.500 62.500
30 900 1040625 140.625
40 1,600 1850.000 250.000
50 2,500 2890.630 390.630
100, &e. 10,000 11562 .500 1562.500
CIRCLE.
. Area Area .
eter: in Squares. | in Hexagons. i
10 78.540 90.811 12.271
20 314.160 363 .247 49.087
30 706.860 817.306 110.446
40 1256.640 1452.990 196.360
50 1963 .500 2270.300 806.800
100 7854 .000 9081.875 1227 .875

G

82 ON THE CORNEA OF THE EYE IN INSECTS.

A few only are necessary in this place ; but even in these
the columns of difference sufficiently indicate the loss likely
to follow from miscalculation. I pass on to notice, however, that
the only quadrilateral figure which will so contain a number of
hexagons that its area may be discovered by squaring a side,
is a rhomb of 60° and 120°; that is to say, two equilateral

triangles placed base to base. When such a plane is occu-
pied by regular hexagons, any side, A B, may be supposed to
consist of small rhombs ranged side by side, each being
exactly one-third (G) of one of the enclosed hexagons. All
the sides are alike; hence it follows that, if one of them be
multiplied into itself, and the product divided by three, the
area of the rhomb, A BCD, in hexagons, is determined.

Let AB = 6 rhombs, then cs = 12 the number of hexagons

in ABCD. But the sides themselves are deduced from a
single row of hexagons E F extending across the rhomb per-
pendicularly with respect to AD and BC; and it is to be
remarked that the number of rhombs in a side is always
double of that of the hexagons composing this perpendicular
series. In the figure there are three such hexagons EF,
and consequently six rhombs ina side. The hexagons can
always be calculated therefore by the formula

(ax ay
3
where a represents the number of hexagons in the perpendi-
=)\2
cular series, Let a@ = 3 then Se = {2 the area of

ABCD.

Allasion has been made to Leeuwenhoek’s calculations of
the lenses of the silkworm’s eye. These may now be cor-
rected.

The number of facets, counted from the base to the

ON THE CORNEA OF THE EYE IN INSECTS. 83

summit of the hemispherical cornea, in the eye of the silk-
worm moth, is thirty-five. But a single row, extending over
a space = one quarter of the great circle of a sphere, x 4
= the circle itself, or 140. Now, the area of a sphere =
four times the area of its great circle, and the area of a great
circle = the square of the diameter x .7854. Again, the
great diameter = the circumference ~ 3.1416. Thus,

140
3.1416
44.563 x 51.525 (i. e., in the ratio of 8 : 9.125) = 2296.108

----- squares of diameter in hexagons
2296.108 x .7854 = 1803.363 - - - area of circle
and 1803.363 x 4 = 7213.452 - - area of sphere in hexagons

7213.452

= 44.565 ----- diameter of the circle

= 3606.726 hexagons in superficies of one he-

2 misphere or eye.
Spherical area according to Leeuwenhoek, with the
hexagons counted as squares = 6236
Spherical area computed as above, with the hexa-
gons considered as such = 7213

Number lost by Leeuwenhoek = Difference - -- 977.

We have seen how easily a surface of hexagons, whether
it be circular or hemispherical, square or rhombic, may be
computed from a single row; and we have now to procure
sections of eyes, presenting such shapes for inspection under
the microscope. ‘To excise small fragments from such minute
and fragile membranes, and those of regular and determi-
nate figures, requires nice manipulation. The quadrilateral
figures I have been in the habit of making, by enclosing the
membrane between two pieces of gummed white paper, upon
one side of which the parallelograms are drawn; they are
then cut entirely through with a penknife, and soaked for a
short time in cold water, which softens the gum, and thus
separates the paper. Circular sections are made with a small
punch, after having been enclosed between paper as above
recommended. On the surface of a small circle of the eye
of a Dragon-fly, excised with the smallest saddler’s punch,
marked No. 1, I have counted about 800 facets; in another,
a size or two larger, about 5000, and so on. I have not felt
satisfied with many of these preparations, however, although
several have come out very well. Their edges are often
lacerated by the punch, while the parallelograms, when
magnified, have presented considerable deviations from the’

a2

84 ON THE CORNEA OF THE EYE IN INSECTS.

true parallel. These inconveniences are obviated by making
smali apertures, of the required shape and size, in black
paper, which are placed immediately over the specimens to
be examined. The circular openings can be punched out,
while the others can be removed with a sharp knife. A
simple and not inelegant mode of procuring very small rhombic
apertures, perfectly equilateral and equiangular, consists in
excising two small equilateral triangles from two slips of
black paper, and sliding one over the other until the small
rhomb in the centre, produced by their mutual intersection,

is of the required size. The cornea is placed under this
rhombic aperture, and the lenses are viewed and counted
through it, by merely enumerating one row extending in a
perpendicular direction, with respect to any two opposite or
parallel sides, and joining them as in the dotted line of the
annexed rhomb.

APPENDIX.

This is the first time, I believe, that the collodion has been
employed in the production of transparent membranes for
microscopic purposes. There are reasons for supposing that
it will enable us to construct a series of novel and highly
inter esting preparations, by its pr esenting the minute tracery
observed on the surface of many opaque objects in a trans-
parent form. In this way we can multiply impressions of
specimens which are very beautiful or very rare. It bids
fair, also, to put us into possession of the general configura-
tion on the surface of certain minute fresh vegetable struc-
tures which become shrivelled, and their beauty obliterated
in drying. It is best applied as follows:—A few chips of
Red Sanderswood are shaken up in a drachm or two of good
collodion ; the surface of the object is then painted over four
or five times, and in less than ten minutes the flake or cast
of collodion can be peeled off, and mounted on a slide under
a thin cover as a dry preparation.

Remarks on the Preparation of the Potyrivoms of ZooruyTEs
for Microscopical Examination, with a notice of the phe-
nomena they exhibit with polarized light. By Goxrpine
Biro, A.M., M.D., F.R.S., Fellow of the Royal College of

Physicians.

ALMOst every miscroscopic observer is familiar with the
extreme beauty of the horny polypidoms of the Anthozoa,
and the calcareous structure of the Polyzoa, when examined
as transparent objects in their recent state. There are few
persons who have not regretted the extent to which these
become disfigured by drying, so as to afford hardly an idea of
the elegance which had previously rendered them so attractive.
The failure of all attempts to preserve them in balsam and
restore them to their original transparency and sharpness of
outline induced me, during a recent visit to the coast of Pem-
brokeshire, to try some experiments in the hope of over-
coming this difficulty, which have yielded some interesting
results.

The great obstacle to preserving these structures in balsam
arises from their retaining, when dried, air in their tubes and
cells so obstinately that it is hardly practicable to get rid of
it, as well as from their shrivelling up in the process of dry-
ing. By the following plan I find the polypidoms may be
preserved as permanent preparations, retaining the appear-
ance of the most beautiful recent specimens, wanting only the
expanded tentacula of the former inhabitants of their cells to
complete the appearance they present when living in their
native seas.

The specimens should, if possible, be preserved in weak
spirit until leisure is afforded for their preparation: if, how-
ever, they have been dried, they should be soaked in cold
water for a day or two before being submitted to the following
processes.

1. Select perfect specimens of the proper size for the
microscope, which in the larger zoophytes should not exceed
two inches in length. Immerse them in water, heated to,
120°, ina glass cylinder, and place them under an air-pump
receiver. Slowly exhaust the air; torrents of bubbles are
given off from the surface of the tubes and cells, and very
soon the water will appear to be in a state of active ebullition.
In a few minutes re-admit air into the receiver, and after a
short time again exhaust; repeat this three or four times.
By this process the air is removed from the cells and tubes,
watery vapour taking its place; at the same time, by the re-
peated admission of water into them, and its removal during
the process of exhaustion, the internal structure of the poly-

86 Dr. GOLDING BIRD ON THE POLYPIDOMS OF ZOOPHYTES.

pidoms becomes freed from the dead polypes and other
animal matter. With the exception of a few of the cellular
Polyzoa, especially Flustra foliacea and Gemellaria loricata, |
have never found any difficulty in thus removing every air-
bubble.

2. The polypidoms should now be removed and allowed to
drain for a few seconds on a piece of bibulous paper, and then
placed in an earthen vessel fitted with a cover and previously
heated to about 200°. The best thing for this purpose is
one of the common, thick, white pots, with its cover, used
used by druggists to hold ointment. These are so thick
that they retain their temperature sufficiently long for the
purpose required, They are most conveniently heated by
boiling them for a few minutes in water, lifting them out with
a pair of forceps, and hastily wiping them with a thick cloth.
The specimens, being dropped into one of these vessels,
and covered with the loosely-fitting lid, are then to be placed
under the receiver of an air-pump, and the air rapidly ex-
hausted. By this process the specimens are very quickly and
completely dried, the water being evaporated from the cells
and tubes so rapidly that they hardly collapse or wrinkle.

3. The specimens are to be removed in an hour or two from
the air-pump, and dropped into a glass cylinder containing
perfectly transparent camphine. This may be quite cold when
the horny, tubular polypidoms, as those of the Sertulariz, are
used, but should be previously heated to 100°, when the cal-
careous, cellular Polyzoa are the objects to be preserved. The
vessel, being covered with a large watch-glass, must be placed
on the air-pump, and the air exhausted and re-admitted two
or three times. After this the vessel may be set aside until it
is convenient to place the specimens in balsam in the following
manner :—

4. One of the slips of glass intended for each specimen
should have a narrow piece of card-board fastened by a little
glue to each end so as to prevent the subsequent injury of the
structure from pressure. The slip thus prepared should then
be carefully cleaned from any dust, and be held over a spirit-
lamp to warm it sufficiently to allow the balsam to flow freely
over it. ‘This should be applied by means of a thick glass
rod, so as to cover the glass with a large body of balsam. All
air-bubbles must be carefully removed by a needle point in
the usual way. Whilst still warm, the polypidoms (previously
removed from the camphine and drained for a minute ina
watch-glass) should be grasped by a pair of forceps and care-
fully immersed in the balsam. A second plate of glass,
without the pieces of card, should be quickly warmed on the
spirit-lamp, and a thin-layer of balsam spread over its surface.

Dr. GOLDING BIRD ON THE POLYPIDOMS OF ZOOPHYTES. 87

It must then be carefully placed over the specimen, by allowing
one end to rest on one piece of card-board fixed to the slip of
glass, and then gradually lowered. If this be adroitly done,
not a bubble of air will be entangled in the preparation. The
plates should then be gently grasped in the middle by the
wooden forceps or fingers, and fastened together by means of
the smallest quantity of sealing wax at each end. Slips of
paper are to be carefully pasted round the sides and ends, and
the preparation may then be preserved without injury.

Thus prepared, such specimens become the most beautiful
of transparent objects for the miscroscope. Their translucency
is as complete as in the fresh zoophyte. The structure of the
cells and vesicles is most beautifully exhibited. Scarcely any
more beautiful objects for the microscope can be thus obtained
than those of the common Sertularia abietina and operculata.
The vesicles in each are most interesting. The curious mouths
of the former, and the opercular lids of the latter, are sure to
arrest the attention. ‘These objects are finely shown by a two-
inch object-glass; the bird’s-head processes of Cellularia
avicularia require, however, an inch-glass ; a deeper objective
being very seldom required, except for making out very mi-
nute structures.

But it is when these objects are examined by polarized
light that the most interesting results are obtained. For this
purpose, let a piece of selenite be placed on the stage of the
microscope, and the polarizing prisms arranged so that the
ray transmitted is absorbed by the analyzer. Of course in
the absence of the selenite, all light would disappear from the
instrument, and none would reach the eye. On placing the
selenite on the stage it will, if of proper thickness, allow an
abundance of green light to be transmitted. Selenite which
presents a bluish or violet tint when thus examined, is not so
fitted for these observations.

If, then, a specimen of Sertularia operculata be placed on the
selenite stage and examined with a two-inch object-glass, a most
beautiful spectacle presents itself. The central stem is shown
to be a continuous tube, assuming a more or less pink tint
throughout its whole extent. The cells assume a bluish or
sometimes violet tint, their pointed orifices, and, indeed, their
whole structure becoming much more distinct than when exa-
mined by common light. The vesicles appear paler than the
rest of the object, and their lids, which so remarkably resemble
the operculum of the theca of a moss, being composed of a some-
what denser structure, generally assume a yellowish or orange
tint, so that they become beautifully distinct. ‘This zoophyte
is often covered with very minute bivalve shells, distinguished
by the naked eye from the vesicles only by their circular form,

88 Dr. GOLDING BIRD ON THE POLYPIDOMS OF ZOOPHYTES.

and these when present add much to the beauty of the speci-
men, presenting a striated structure, and becoming illuminated
with the most brilliant colours.

Thus, when submitted to polarized light, the zoophyte
becomes not only a most beautiful, but an instructive object,
the relation of the cells to the tube which bears them, and the
continuity of the latter being so readily seen. Sertularia fili-_
cula is also an interesting object, the waved stem or central
tube becoming of a deep dusky red, whilst the cells assume
but little colour, renders their mutual relation very obvious.
Sertularia abietina is also a fine object, especially when loaded
with vesicles as it so often is in the autumn. Halecium
halicinum, perhaps the least elegant of this class of beings,
assumes a very interesting appearance, its cells assuming a
moderate amount of colour. The very beautiful Plumularia
falcata acquires fresh beauty under polarized light; for
although its cells do not become coloured, merely assuming
a pale green, yet the tubular stem becomes more or less of a
crimson hue, presenting the appearance of a beautiful feather.
It is really remarkable how much more distinct every structure
appears, and how much greater a charm is thrown over the
elegant structure of the polypidoms when examined in the
green light of the selenite. They seem almost, to an imagina-
tive eye, to be once more in their native element.

The most splendid tints are exhibited by the calcareous
siructure of the Polyzoa, and among these the Flustra trur-
cata is perhaps the most interesting. When a preparation of
this zoophyte is examined by polarized light with a two-inch
glass without the selenite, the structure of the cells, and the
shape of their mouths, are well seen ; but in several portions
of the specimen the walls of the cells present the appear-
ance of a tesselated pavement, several minute, spherical,
coloured structures being scattered over it. On replacing the
object-glass by one of one-half inch focus, these spherical
bodies present the dark cross with beautiful tints in each
quadrant, at first sight resembling the carbonate of lime I
discovered some years ago in the urine of the horse. On
examining them carefully, however, the polarizing structure
will, in many of them, be found to be identical with that seen in
the crystalline lens of the cod, or in a spheroid of unannealed
glass when immersed in oil, and different from that of a slice of
cale-spa or circular plate of unannealed glass. The centre of
each spherule being occupied by a black cross with the tinted
quadrants, the whole being circumscribed by a black circle.
Beyond this extends a second set of black arms with more
varied tints between them. A more interesting structure
I have never had occasion to examine than that presented by

Dr. GOLDING BIRD ON THE POLYPIDOMS OF ZOOPHYTES. 59

these spherules of carbonate of lime. On placing the selenite
plate under the specimens, the black cross and circle became
green; and a very beautiful result occurs from some tints
being raised, and others depressed, in the scale of colours.
On digesting a piece of Flustra truncata in diluted hydro-
chloric acid, and then putting it upon balsam, like the fresh
specimen, this beautiful structure disappeared; all appear-
ances of tessellated tints and coloured spheres had vanished.
Hence they depended upon the crystallized arrangement of
the carbonate ot lime.

The more common Flustra_foliacea is an interesting object
on the selenite stage, but does not exhibit the peculiar polar-
izing structure of the other species.

The Cellularia avicularia is a brilliant object with the
selenite stage, its cells being covered with plates of carbonate
of lime; it presents a fine display of tints, the bird’s head
appendages being exceedingly beautiful.

The Gemellaria loricata is one of the most beautiful objects
with the selenite, the cells assuming a pale pink, and the
obovate orifices of each—provided apparently with a frame of
carbonate of lime to keep them patent—assumes a fine and
rich orange tint.

I have alluded to some of the most beautiful of the struc-
tures which have occurred to me; but I feel sure, that those
observers who have more time at their disposal, will add to
our knowledge of the diversity existing between the polarizing
structure of these polypidoms. I would especially draw atten-
tion to the curious spherules of Flustra truncata; they
deserve a very careful examination. I was disappointed in not
detecting a similar structure in the birds’ heads of Cellularia.

I cannot close this little communication without alluding to
an excellent and very simple plan for preserving the zoophytes
as wet preparations, so as to retain the polypes and their ten-
tacular arms in situ. Ellis stated nearly a century ago, that if
the zoophytes were plunged into brandy so as to kill them
speedily, they might be preserved for a long time. I find,
however, that it is better to select a very vivacious specimen
and plunge it into cold pure water—the polypes are killed
almost immediately, and their tentacula often do not retract:
proper sized specimens should then be selected, and _pre-
served in weak alcohol. For this purpose little phials* about
two inches long should be made, from very thin, flat glass
tube, so as to be half an inch wide and about a quarter of an
inch, or even less, from back to front. The specimens being

* Mr. Pastorelli, of Cross-street, Hatton Garden, who has taken much
pains to manufacture these little flat phials, supplies them at a very low
price.

90 COBBOLD ON THE ORCHIS MASCULA.

fixed to a piece of thin platinum wire, should then be placed
in one of these flat phials (previously filled with weak spirit),
so as to reach about half-way down. When several of these are
thus arranged, they should be placed in a glass cylinder and
removed to the air-pump. On pumping out the air, a copious
ebullition of bubbles will take place, and many of the tenta-
cula, previously concealed, will emerge from the cells. After
being left ix vacuo for a few hours the bottles should be filled
up, closely corked, and tied over, like common anatomical
preparations. I find that, for all examinations with a one or
two-inch object-glass, these bottles are most excellent, and afford
cheap and easy " substitutes for the more expensive and diffi-
cultly managed cells. In this manner specimens of the genera
Cycloum, Membranipora, Aleyonidium, and Crisia, exhibit their
structure most beautifully.

A few dozen of these little bottles hardly occupy any room,
and would form a useful accompaniment of the microscopist
by the sea-side: Any one who would visit the caverns in
St. Catherine’s Island, at Tenby, could reap a harvest which
would afford instruction and amusement for weeks. In these
caverns, so rich in zoophytes and sponges that they are really
roofed with the Laomedee, Grantie, and their allies, whilst
the elegant Tubularie afford a garden-like ornament to the
shallow pools on the floor, the walls abounding with the pink,
yellow, green, and purple Actinie, days may “be spent with
instruction and amusement of the most interesting kind. 1
have, indeed, been informed by my friend Mr. Dyster, of Tenby,
who has devoted himself to the investigation of the inhabitants
of these caverns with great zeal and success, that no locality
affords, in the same space, such an abundant treat for the
zoophytologist. I cannot too strongly recommend a visit to
them, to all who have a few days leisure in the summer.

On the Embryogeny of Orcuts mascuta. By T. Spencer
Cossotp, M.D., formerly Senior President of the Royal
Medical Society of Edinburgh.

Arter the elaborate memoir of M. Tulasne on the vegetable
embryo in the ‘Annales des Sciences Naturelles’ for 1849,
containing not only the results of his own extended investi-
gations, but embodying a complete analysis of all that has
been previously written on this subject, it is with diffidence
that I offer the following details, which are chiefly con-
firmatory of facts already elicited. "The reviewer of Professor
Quekett’s Lectures on Histology in the first Number of this
Journal, page 44, hints that “the question of the entrance of

COBBOLD ON THE ORCHIS MASCULA. 9]

the pollen tube into the sac of the embryo” is still one of
interest to vegetable physiologists ; this remark has suggested
the present communication.

Of all the natural orders hitherto examined by the embryo-
logist, few have been more clesely studied or yielded more
satisfactory results than the Orchidacee: the researches of
Brown, Amici, Mohl, Muller, Hofmeister, and many others,
are too well known to require recapitulation; our own in-
quiries have extended over a large number of genera, but the
selection of a single species sufficiently demonstrates the
question under consideration.

Referring at once to the illustrations, fig. 1. will be recog-
nized as a floret of Orchis mascula, with the peduncle (p) and
bract (6) attached. Before fertilization is accomplished, the
peduncle (which encloses the ovarium) begins to enlarge, con-
sequent upon the growth of the contained ovula. Plate IL,
figs. 2, 3, 4, and 5, indicate the successive stages of develop-
ment of the ovula; their first appearance is only recognised
by a slight bulging outward of the cellular parietes (placente)
of the ovarian chamber, in the form of papillz, which are the
representatives of the nucleus of the perfect ovulum (marked
nin all the figures). The mode in which the primine (pr.)
and secundine (se.) are developed, and subsequently enclose
the nucleus, is also well shown. Some time after impregna-
tion has been effected, the condition of the ovary assumes the
appearance seen in fig. 6, a ‘section of which, slightly magni-
fied, is given in fig. 7. Bundles of pollen-tubes (pt.) run
along the inner side of the placentz and terminate by short
curves, entering the micropyles of the ovula (ov.); on the
left side of the figure their distribution is well exhibited, the
ovula being detached, and the pollen-tubes left pendant.

Examining the ovules at this stage, we now perceive a cavity
in the centre of each nucleus; this is surrounded by a cell-
wall, and constitutes the embryo sac (fig. 8, es.). In the
interior of the sac granular matter exists in more or less
abundance, being generally found thicker near the apex ; but,
whether or not distinct cytoblasts or embryonic vesicles exist
prior to the contact of the pollen-tube with the embryo sac
(as is indubitably the case in numerous other phanerogamia),
is a point not fully determined. In those instances where we
have witnessed the union of the pollen-tube with the embryo
sac, the granular matter has usually been found collected
together opposite the point of application (figs. 9 and 10),
and, in one instance, three embryonic vesicles (ev.) were
visible at the apex of the sac, the pollen-tube remaining
firmly adherent (fig. 11). This latter observation, agreeing
as it does with what we have ourselves observed in Gesnerea,

92 BEALE ON SUBSTANCES OF

and being also in accordance with the views advocated by all
later authorities, we think we cannot better close this short
paper than by drawing the following conclusions, which may
be regarded as embracing the leading facts and particulars
hitherto promulgated on this interesting subject :—

1st. That prior to impregnation the ovule contains an
embryo sac. 2nd. That the embryo sac is commonly formed
at the apex of the nucleus. 3rd. That in the interior of the
embryo sac there exists a granular fluid or formative blastema.
4th. That the sac frequently protrudes beyond the exostome
(ovule tube; Griffith, Dickie). 5th. That in the interior of
the sac, prior to impregnation, one or more cytoblasts, or
embryonic vesicles, are formed. 6th. That their formation
takes place by the aggregation of molecules. (Amici, Meyen,
Hofmeister.) 7th. That the cytoblasts, or embryonic vesicles,
also contain a fluid more or less granular. (Globulo-cellular
cambium ; Mirbel.) 8th. That the pollen is always necessary
for fertilization (apparent exception given by Smith in Celo-
begyne ilicifolia). 9th. That the pollen, when applied to the
stigma, sends out one or more tubes (prolongations of the
intine), which contain granular matter (fovilla), 10th. That in
most cases the union of the pollen tube with the apex of the
embryo sac constitutes the very act of impregnation. 11th.
That the result of this union is the formation of an embryo.
12th. That this formation takes place either by the meta-
morphosis of one of the pre-existing germinal or embryonic
vesicles, under the dynamic influence of the fovilla (acting
catalytically ?); or, as is more probable, by the union of the
contents of the pollen-tube with that of a germinal vesicle,
similar to what occurs in the conjugation of Conferve.

On the Importance of recognising Substances of extraneous Origin
when they occur in Urine, and of distinguishing them from
those Bodies which enter into the Composition of Urinary
Sediments. By Lionet Beare, M.B.

In the microscopical examination of urinary deposits, the
observer often meets with substances whose nature and
origin cannot readily be determined. This is due in many
instances to the presence of bodies which have fallen in
accidentally, or which haye been placed in the urine for the
express purpose of deceiving the practitioner. The im-
portance of recognising matters of an extraneous origin can
scarcely be sufficiently dwelt upon, for until the eye becomes
familiar with the characters of these substances, it will be
obviously quite impossible to derive such information from a

EXTRANEOUS ORIGIN IN URINE. 95

microscopical examination of the urine, as will enable the
observer to distinguish between those substances whose pre-
sence denotes the existence of certain morbid conditions, from
certain matters which have accidentally found access, and
may therefore be entirely disregarded. Practitioners who
use the microscope for investigating the nature of urinary
deposits, will derive advantage from subjecting many of the
substances referred to in the present communication to mi-
croscopical examination, by which their general appearance
will soon become familiar to the observer, and he will then
be able to recognise them without difficulty should they be
met with in the course of an examination of urine. ©

As most of the undermentioned substances are readily
obtained, a brief notice of their characters will be sufficient ;
the chief object of this communication being to direct the
notice of practitioners to the fact of the frequent occurrence
of many of them in urine, and to draw attention to those
characters in which they resemble, or are liable to be mistaken
for, any insoluble constituent of the urine. I may remark
that among many substances whose presence is accidental in
urine, the following are some of the most important that have
fallen under my own notice :—Human hair, cats’ hair, blanket
hair, coloured worsted, fibres of cotton, flax, and silk, small
portions of feathers, fibres of wood swept from the floor, starch,
globules of various kinds, fragments of potato, bread-crumbs,
portions of tea-leaves, common house sand, oil globules. Once,
a specimen of urine, which had been sent to Dr. Todd for
examination, was found to contain several white bodies about
half an inch in length, which upon microscopical examination
I found to contain trachew, and they ultimately proved to be
larve of the blowfly, although it had been stoutly affirmed
that these had been passed by the patient. A few days since
Dr. Stewart informed me that a man had brought some urine
to him for examination with a thick bright red deposit, which
was analyzed by Mr. Taylor, and proved to consist of sesqui-
oxide of iron. The urine containing this deposit was of spe-
cific gravity 1011, and, upon the addition of ammonia, a brown
flocculent precipitate (hydrated sesquioxide of iron) was thrown
down. Dr. Stewart tells me that a considerable quantity of
the powder remained suspended in the urine after it had stood
for many hours, and that the fluid was still turbid after having
been passed through a double filter. The man who brought
this urine has also been endeavouring to impose upon my
friend Dr. Weber, of the German Hospital.

Hiair of various kinds is very frequently found amongst
urinary deposits, but, as its microscopical appearance is so
well known, it is not necessary to enter into a description

94 BEALE ON SUBSTANCES OF

of the characters by which it may be distinguished. The
varieties of hair most commonly met with are human hair,
blanket hair, and cats’ hair; not unfrequently portions of
coloured worsted will be found, but the colour alone will
often remove any doubts with reference to the nature of
the substance. Portions of human hair are sometimes liable
to be mistaken for narrow casts of the uriniferous tubes
—such as are quite free from epithelium or granular mat-
ter, and which present throughout a homogeneous appear-
ance. The central canal in many cases will be sufficient
to distinguish the hair from every other substance likely
to be mistaken for it, but sometimes this cannot be clearly
made out, and the marks on the surface may be indistinct,
when attention must be directed to its refracting power,
well-defined, smooth outline, and also to the sharply trun-
cated ends, or to its dilated club-shaped extremity in the
case of the hair bulb. In these points small portions of hair
will be found to differ from the cast, for this latter does not
refract so strongly, the lines on each side are delicate but
well defined, and the ends are seldom broken so abruptly as in
the case of the hair. Cats’ hair can scarcely be mistaken for any
urinary deposit with which I am acquainted, and its transverse
markings will serve at once to distinguish it with certainty.

Cotton and flax fibres are very often found in urine. When
broken off in very short pieces they may be mistaken for
casts, but the flattened bands of the former, and the some-
what striated fibres of the latter, will generally be found suf-
ficiently characteristic.

Portions of feathers are often detected in urinary deposits
upon microscopical examination, and are derived, no doubt,
from the bed or pillow. Their branched character will
always enable the observer to recognise them with certainty.

Pieces of silk are not unfrequently present, but these can
scarcely be mistaken for any substances derived from the
kidney. Their smooth, glistening appearance and small
diameter at once distinguish them from small portions of
urinary casts, and their clear outline and regular size from
shreds of mucus, &c.

Fibres of deal from the floor. Of all the extraneous mat-
ters likely to be met with in urine, and calculated to deceive
the eye of the observer, none, perhaps, is more liable to be
mistaken for a portion of a transparent cast, than a short piece
of a single fibre of deal. In hospitals, where the floor is un-
covered and frequently swept, portions of the fibres of the
wood are detached, and, being light, may be very readily
blown into any vessel which may be near. In fact, these fibres
enter largely into the composition of the dust which is swept

EXTRANEOUS ORIGIN IN URINE. 95

up. I became familiar with the appearance of these bodies
for a long time before I ascertained their nature, for, although
the peculiar character of coniferous wood is sufficiently well
marked, when only very small portions are present, and in a
situation in which they would scarcely be expected to be
met with, their nature may not be so easily made out. Often
only two or three pores may be seen, and not unfrequently
these are less regular than usual, in which case they may
be easily mistaken for a small portion of a cast with two or
three cells of epithelium contained within it. I have very
frequently met with these fibres amongst the deposit of
various specimens of urine which have been obtained from
patients in King’s College hospital.

Starch granules are very commonly found in urinary de-
posits; usually their presence is accidental, but large quanti-
ties of starch have often been added for purposes of deception,
in which case their true nature may be discovered, either
by their becoming converted into a jelly-like mass on being
boiled with a little water in a test tube, by their behaviour
upon the addition of free iodine, or by their well defined
microscopical characters. The three kinds of starch most
likely to be met with in urine, are potato starch, wheat
starch, or rice starch. They are readily distinguished by
microscopical examination. Small portions of potato, or pieces
of the cellular network, in which the starch globules are con-
tained have been occasionally met with. Under the head of
starch, may-also be included bread-crumbs, which are very
commonly present in urine, and have a very peculiar appear-
ance, which may be so easily observed, that a description
would appear superfluous. Many of the starch globules will
be found cracked in places, but their general characters are
not otherwise much altered.

Portions of tea-leaves are occasionally found in urine. The
beautiful structure of the cellular portions, and the presence
of minute spiral vessels, distinguish this from every other
deposit of extraneous origin. A small piece of a macerated tea-
leaf will be found to form a most beautiful microscopic object.

Milk is sometimes purposely added to urine, in which case
there is danger of mistaking the specimen for one of the so-
called chylous urine, from which, however, it may be easily
distinguished by the presence of small oil-globules, with a
well defined dark outline, while the fatty matter in chylous
urine is in such a minute state of sub-division, that it only
presents a granular appearance under the microscope.

Fatty Matter. The existence of fatty matter in urine is a
subject of so much importance to the practitioner, and its
accidental presence so frequent, that it may be well to consider

96 BEALE ON SUBSTANCES OF

the different forms in which it occurs, instead of simply
describing the manner in which fat of accidental origin may
be distinguished from oily matter, which has been excreted
by the kidney. Upon the presence or absence of this deposit
often depends the prognosis of a case, and hence it is of the
utmost importance to recognise that form which is charateristic
of fatty degeneration of the kidney with certainty.

Fatty matter occurs in urine in at least three distinct forms.
The first form which I shall notice, is that in which it is
met with in certain specimens of chylous urine, and the
peculiar milky appearance of the secretion is entirely due to
the existence of fatty matter in an exceedingly minute state of
division. Upon microscopical examination of such a speci-
men, all that can be detected is a multitude of minute granular
particles, not unlike those of amorphous lithates, scattered all
over the field. Upon carefully focussing, it will be observed
that each particle is in constant motion, and the movements
resemble those met with in chyle and certain other fluids.
That these particles are really composed of fatty matter in a
minute state of division is shown, by the addition of ether to
the urine, which immediately becomes clear; and by the
evaporation of the etherial solution, the fatty matter may be
obtained in its usual form. From a remarkable specimen of
the so-called chylous urine, for which I am indebted to the
kindness of my friend Mr. George Cubitt, I obtained as much
as 13-9 grains of fatty matter from 1000 of urine; the whole
of this large quantity having previously existed in the urine
in the minute state of division to which I have just alluded.
In such instances, it is clear that from microscopical examina-
tion alone, it would be quite impossible to determine the
nature of the substance to the presence-of which the peculiar
character of the urine was due.

The second form in which fatty matter is found in urine is
that of globules, each globule consisting of one portion of
fatty matter, which either floats freely upon the surface of the
urine, or is carried to the bottom in consequence of becoming
entangled in some heavier deposit, as for instance mucus, or
cells of epithelium. In this case, the oil particles will pro-
bably not be very numerous, and they are too large to give to
the urine the opalescent appearance, which results from the
suspension of fatty matter in a molecular state. The globules _
appear in the microscope as highly refractive particles, of a
perfectly circular form, with a dark and well defined outline.
The more minute of these globules present the appearance of
a perfectly round black spot. It is in the form of distinct
and separate globules that fatty matter is found in urine,
when it finds access into that fluid accidentally, as, for instance,

EXTRANEOUS ORIGIN IN URINE. OY

if a small particle of butter or a little oil fall into the urine ;
or if urine drawn off by an oiled catheter be subjected to
examination, the oil globules will present this character, and
usually they vary very much in size, some being often of
considerable diameter.

The third form in which fatty matter is met with in urine,
differs from the preceding in this essential particular, that
many distinct and separate oil globules, often varying much
in size, will be found collected together ia the interior of a
cell; at the same time, a certain number of free oil-particles
may be observed. In a collection of oil particles invested
with a cell-membrane, the term “ fat cell” has been applied,
and it is to these cells found in the deposits, and entangled
in casts of the uriniferous tubes, that so much attention has
been directed of late, in reference to the mdications of the
existence of fatty degeneration of the kidney afforded by the
presence of these bodies in the urine.

Hence by carefully observing the particular character
which the oily matter assumes, there is little danger of being
mistaken in reference to its origin.

Infusoria and fungi.—After urine has been kept for some
time, various forms of fungi, and not unfrequently some in-
fusorial animalcules may be present—vibriones, vorticella,
and monads are among those most commonly met with, but
many other forms are frequently present. The period of time
which elapses previous to the development of vibriones and
fungi is found to vary very much in different cases; these
bodies being sometimes found in urine within an hour after it
has been passed, while in other cases the urine may be kept
for many days without the development of any animal or
vegetable organisms whatever.

Many other matters of extraneous origin frequently form-
ing part of an urinary sediment might be here described, but
as most of these will doubtless occur to the mind of every
observer, and as their nature is often easily determined, it is
unnecessary to enter into further description, which would
prolong this paper to too great a length. It is hoped, how-
ever, that enough has been said to draw the attention of
observers to the importance of the subject, and to point out
the necessity of rendering the eye familiar with the characters
of many other substances than those which really enter into
the formation of wrinary deposits, before the microscopical
examination of urine can be successfully employed in clinical
investigation.

VOL, I, H

Osoer'y

TRANSLATIONS.

Description of Actinophrys Sol. By A. Ké turer. From
Siebold and KGlliker’s Zeitsch.: 1., p. 198. 1849.

(Continued from page 34.)

General Considerations.

To the above description of Actinophrys, it will not be out
of place to add a few general reflections, and in the first place
to ask what systematic position it is entitled to take.

When compared with the simplest known forms of animal
life, it appears clear that Actinophrys is most closely allied to
Ameba and the Rhizopoda of Dujardin, who himself agrees in
this view, and considers that it differs from them only in the
uncommon slowness with which the tentacles are moved. In
fact Actinophrys, like Ameba, Gromia, &c., consists of a per-
fectly homogeneous, everywhere contractile substance, without
any trace of structure, and having in precisely the same way
processes on the surface of an ephemeral nature and of various
forms. The granules also of Actinophrys and its clear spaces
have their analogues in the granules of Amewba and Gromia and
in the vacuoles of Amwba, Arcella, Trinema, and Gromia.
And just in the same way an Actinophrys artificially divided
by Eichhorn, finds its exact counterpart in an Amoeba prin-
ceps, the same observation being made also by Dujardin. It
must be confessed that, notwithstanding this correspondence,
Actinophrys exhibits a great peculiarity in its mode of taking
nourishment. But is it ascertained, it may be asked, that the
Ameebz and Rhizopoda take in their food in any other way ?
By no means; much rather does it seem, to the author at
least, from all that is known as to the mode of feeding in those
creatures, to be indicated, that it is precisely similar to that
which obtains in Actinophrys. We have only to refer to
what Dujardin remarks with respect to Ame@ba (Infus., p.
228 et seq.) to see that he was very near the discovery of the
remarkable proceeding witnessed by the author in Actino-
phrys. Referring to the circumstance that in the first place
there is in Ameba neither mouth nor intestine, and secondly,
that, nevertheless, Navicule, Closteria, fragments of alga,
and other nutritious particles occur abundantly in its interior,
having been admitted at any part of the surface at will—it
may be held as an established fact, that the admission, diges-
tion, and rejection of the food is effected in Amwba precisely

KOLLIKER ON ACTINOPHRYS SOL. 9

in the same way as in Aetinophrys. Dujardin, moreover,
himself, although he assumes that the Amcebe are nourished
by means of absorption, a and that the nutritious matters above
mentioned, enter them only by accident, is not inclined to deny
that they do derive nutriment from the articles thus in-
cluded ; adding (p. 229)—‘ Si toutefois on voulait prétendre,
que ces corps étrangers sont entrés par une bouche, et sont
logés dans des estomacs, il faudrait admettre, que cette bouche
sest produite sur un point quelconque, et la volonté de 0 Amibe,
pour se refermer et disparaitre ensuite, (this recalls Ehbrenberg’s
expression (p. 128), that the true mouth of the Ameba opens
only in the act of swallowing and rejection,) tandis que les
estomacs eux-mémes, dépourvus de membrane propre, se creu-
seraient indifféremment ¢a et la au gré de l’animal, pour dis-
paraitre de méme; dans ce cas les mots seuls seraient diffé-
rents et l’explication des phénomenes resterait encore celle, que
jai donné” The latter is by no means credible, and it is
rather to be asserted that it is not by chance, but by will (sit
venia verbo) that the food enters the body in the Ameba.
What holds good in Ameba may also be supposed to be
the case in the closely-allied Rhizopoda, which, although they
have no vestige of a mouth, nevertheless contain Infusoria and
Bacillariz, as has been seen by Dujardin in Arcella vulgaris
(p. 247) and Euglypha tuberculata (p. 251), and by Ehren-
berg in Difflugia enchelys (p. 1382) and Arcella vulgaris (p.
133), where even it is remarked, that the latter takes in
Indigo, and that in feeding, a spot in the interior of the soft
body—from time to time opens and closes—of which spots also
two are frequently present,

Relying upon all this, the author is of opinion that Actino-
phrys belongs to the same group with Ameba and the
Rhizopoda of Dujardin, and to which group the latter name
seems most appropriate. Distinct families would be formed
of the Ameebe, the species of Actinophrys, to which probably
also the genus Acineta would belong; and of those provided
with shells, which again might be divided into those with a
simple body (Arcella, Diffiugia, Gromia, &c.) and those with
a simple semi-divided body, the Polythalamia (Miliola, Vorti-
cialis, &c.). The character of these Rhizopoda would in part
be that already given by Dujardin: a structureless body of a
homogeneous, contractile substance, without mouth, intestine,
or other organs, with mobile processes. Reception of food at
any part of the surface of the body, by a retraction of the sub-
stance and the introduction of the morsel into the interior ;
digestion of the aliment in spaces temporarily formed for the
purpose, and expulsion of the remains at any spot at will,
Propagation by fission? by germs ?

u 2

100 KOLLIKER ON ACTINOPHRYS SOL.

Having thus shown the alliance of Actinophrys with
Amoeba, Gromia, &c., the position of the thus constituted
Rhizopodous group with respect to the rest of the lower
animals remains to be considered. The first question which
here arises is, whether this group is to be placed with the
Infusoria, or should constitute an independent class. The
answer is difficult, since the structure of the Rhizopoda and
Infusoria is, it must be regretted, not yet so clearly made out
in all points as to admit of a certain comparison between
them. The author starts with the proposition that the Infusoria
(from which he excludes the Rotifera, and the Bacillaria,
Volvocina, and Closterina belonging to the vegetable king-
dom) all without exception consist of a single cell. He 1s
of opinion that what he had shown to be the case in the
Gregarine,* holds good of all the true Infusoria, as has been
shown in the most convincing way by Siebold in his Compa-
rative Anatomy. In this view all the Infusoria consist as it
were of a cell, which in the one case is entirely closed (Gre-
garina, Opalina, Euglena,t &c.); and in the other possesses a
mouth or even two openings. No one who examines with
sufficient attention an Opalina, Bursaria, Nassula, &c., can
longer entertain the smallest doubt as to this. He will find
for the most part a contractile and structureless membrane fur-
nished with cilia, frequently partially contractile cell-contents
with granules and vacuoles, and almost always an homogeneous,
frequently curiously formed nucleus.

This point being once established, it may be asked, in the
second place, Can the Rhizopoda be likened to a cell? At
first sight the answer would appear to be in the negative,
seeing that they (Ameba, Actinophrys, &c.) have no distinct

* That the Gregarine are unicellular cannot for a moment be doubted
by any one who has once seen these creatures ; but, on the other hand, it
has hitherto been a question whether they were complete animals or not.
The author thinks that this point may now be considered as settled, since
his more recent observations (Mittheilung. der Ziiricher. naturf. Gesell-
schaft, heft i., 1847, p. 41, and 8. and K., Zeitsch., vol. i. p. 1, et seq.),
and which have been confirmed by many excellent observations by Stein
(Mill. Archiv., 1848, p. 182) have shown clearly that the so-called
Psewlo navicelle are the germs of Gregarine. He would here, however,
remark cursorily that the metamorphoses of the Gregarine into Pseudo
navicellw, apparently from their connexion in pairs, cannot be compared
with a conjugation, as Stein is inclined to do, because in this connexion
the contents of two Gregarine are not mixed together as is the case in the
conjugation of the alge, without exception, with the contents of the
united cells.

+ As there is scarcely any reason for doubting that Euglena properly
belongs to the Monadina, and that it is a plant, it should be removed from
the above category. Nor has it any distinct cell-wall, being composed
wholly of a mass of protoplasm.—T.

KOLLIKER ON ACTINOPHRYS SOL. 101

tunic equivalent to a cell-wall, and, at least many of them, no
cell-nucleus. But it must be inquired, Is this sufficient to
deprive them of the title of cells? With respect to the
nucleus, it really appears to be present in some of them
(vid. Ehrenberg’s figures), and where it is wanting, as in
Actinophrys, whose nuclear and vesicular internal substance
above described can here hardly be so regarded, a true nucleus
may have existed at an earlier period, and be absent only in
the full grown animal; or again it may be entirely wanting,
and still the animal regarded as a cell. The former supposi-
tion is highly credible, the same thing taking place in many
cells (human blood-corpuscle, &c.) ; and with respect to the
latter, it may be remarked that although in the higher animals
the nucleus is a constant element in the cell, it is stil] not
proved, that, speaking generally, there cannot be a cell without
a nucleus, that i is to say vesicles, which otherwise in all respects
as to growth, reception and rejection of nutriment, movement,
increase, &e., behave exactly as do cells. It may here ‘©
stated that certain Infusoria, which on account of their great
resemblance to others, distinctly unicellular, must be taken to
be altogether of a like nature, nevertheless have no nucleus.
With respect to the membrane, it may be regarded as certain
that there are cells with a membrane of such extreme tenuity
as to be hardly distinguishable from the contents; thus the
author observed in blood corpuscles of the embryo chicken
noticed in the act of division, that when pressure was made
upon them, the two halves became separated, and without any
escape of colouring matter, were again formed into perfect cells.
The blood corpuscles of the Frog under pressure behave very
nearly like the soft substance of ie filaments of Actinophrys,
the processes of Ameba, Gromia, &c. In the second place,
it is to be remarked that there are cells, in which at a later
period all difference between the membrane and the contents
disappears—for instance, the elements of the smooth muscles
in the higher animals—what are termed by the author fibre-
cells. Which of these possible conditions, as concerns mem-
brane and nucleus, obtains in the Rhizopoda, the author is
unable to answer, not knowing with certainty whether they
are to be regarded exactly in the light of cells or not, but he
goes on to remark that their other relations are not opposed
to the notion that they may be simple cells ; such as their
structureless homogeneous contents, its contractility, and the
vacuoles in it, resembling in all respects the contents of the
body in the unicellular Infusoria ; then the simplicity of their
form and mode of taking food, so closely resembling the way in
which the Infusoria introduce a morsel into their parenchyma

JQ2 KOLLIKER ON ACTINOPHRYS SOL,

and there digest it. Certainly the presence of a cell-membrane
is scarcely reconcilable with the circumstance that the body is
capable of admitting a morsel of food at any part of the
surface, but partly, it is not indispensably necessary to assume
that such exists in the fully developed Actinophrys, and
partly also it is by no means wonderful that a membrane, in
consistence almost the same as the rest of the parenchyma,
should be capable of being torn and of reuniting. To leave,
however, this region of hypotheses and possibilities, it may at
all events be stated that the notion that the Rhizopeda are
of a nature similar to simple although modified cells, has
especially this to recommend it, that there is little else to be
made of them. It cannot be admitted that they consist of a
whole aggregation of cells, and as little is it to be supposed
that they are simply a mass of animal matter without further
distinction, as it were, an independent living cell contents. And
the less can this supposition be entertained, because, according
to all recent investigations which have proved cells to be the
elementary parts of the higher animals and plants,—as the
initial point for further development (ova, spores, &c.), as the
simplest form of vegetable organisms (Closterium, Navicula,
unicellular Algz, &e. ), we cannot in the animal kingdom also,
but regard the unicellular animal as the simplest form.
On this account it seems provisionally, best to consider the
Rhizopoda as peculiarly modified simple cells—which pro-
bably may have a membrane, but in tiie mature condition at
least, to all appearance have no nucleus, and to arrange
thet together with-the other Infusoria in the class of Unicel-
lular animals.

In conclusion, the author adds a few words respecting the
contractile substance of Actinophrys and the Rhizopoda in
general. He is induced the more to do this by a very in-
teresting Memoir by A, Ecker, ‘On the Structure and Life
of the Contractile Substance of the lowest Animals.’ * The
contractile substance presented in the Rhizopoda is evidently
very nearly allied, physiologically and chemieally, as well as
in external appearance, to that which Ecker describes in
Hydra, and has shown to exist also in other animals, and from
the author’s observations on those animals he cannot but
confirm Ecker’s statement. This contractile substance, termed
by Ecker ‘ amorphous’ (an improved edition of Dujardin’s
Sarcode), deserves in every case to be further investigated in
the way pointed out by Ecker, and to be compared with the
contractile elements in the higher animals, Already, as it

* §. and K,, Zeitsch., B. i. 'p. 218,

KOLLIKER ON ACTINOPHRYS SOL. 103

seems to the author, is an interesting law apparent when all
contractile parts are regarded, that only two such occur
in the animal kingdom,— Cell-membrane and Cell-contents,
which either by themselves alone or together constitute a con-
tractile element. Other parts, such as the cell-nucleus and its
derivatives—nucleated fibres, and elastic fibre—amorphous
substance not deposited in cells—coagulated fibrine, &c., are
never contractile.

1. Contractile cell-membranes occur :

a. In unicellular animals. 1. As universally contractile
membranes, such as are met with in Gregarina, Leucophrys,
Coleps, Trachelius, Loxodes, Bursaria, Kolpoda, Uroleptus,
and many other infusoria. 2. As motile processes of a con-
tractile or motionless membrane (Opalina, Bursaria, &c.).

b. In aggregated simple cells, 1. As in membranes con-
tractile in toto, as in the heart-cells of the embryo in Alytes
and Sepia, the cells of the embryo Planaria, and those in the
tail of the larve in the Tunicata (Ann. d. Sc. Nat. 1846,
p. 221), and the caudal vesicle of the Limax embryo (Ecker,
Iscs).

2. As partially contractile membranes, cilia, or epithelium
cells,

c. In cells which are united so as to form a tube, capillary
lymph, and blood-vessels.*

Contractile cell-contents occur :

a. In unicellular animals. In all infusoria in which there
are contractile spaces, a part at least of the contents or paren-
chyma is contractile.

6. In non-independent cells. The spermatic filaments of
animals which are here meant, originate as a deposit in the
interior of cells, or, more correctly, in the nucleus of the sper-
matic cells.

* That the structureless walls of these canals are of the nature of
coalescent cell membrane was shown by the author in the ‘ Ann. d. Sc.
Nat., 1846.’ It is true that Bidder (‘ Verhaltniss d. Ganglien-K6rper zu
den Nervenfasern,’ 1847, p. 53) has recently termed the Author’s statements
merely conjectures, although, as it would appear, simply upon the ground
that they do not accord with his own real conjectures (l.c. p. 54). He
adduces no facts contradictory to the Author’s statements, and relies solely
upon the law propounded by Reichert, and adopted by no one but himself,
and which is altogether incorrect—viz. that elementary forms of different
histological importance never enter a continuous connexion with each other.

This is not the place to remark farther upon this question, and the
author contents himself with observing, without meaning anything per-
sonal, at least this much, that those who upon actual examination of the
capillaries of the Batrachian larva do not see that they are formed from
outstarting processes and stellate cells, have not claim to the title of
microscopist.

101 KOLLIKER ON ACTINOPHRYS SOL.

c. In tubes formed out of coalesced cells. Under this head
are to be reckoned the animal or striped muscular fasciculus,
im which the contents are represented by the primitive fibrille,
and the tubes formed out of coalescent cells by the Sarco-
lemma.*

2. Contractile membranes and contractile cell-contents,
united into one body are seen :-—

(a). In unicellular animals ; premising that Actinophrys and
the Rhizopoda come under this head.

(6). In multicellular animals ; in which all the cells have
coalesced to form a homogeneous substance. Under this head
are to be reckoned :—

1. The Hydrz. These, according to Ecker’s investigations,
exhibit no trace of cells—nothing, in fact, but a uniform sub-
stance ;—they must, therefore, at least according to the author’s
view, be regarded as originally composed of a mass of cells,
since we know that they are developed from ova, which have
undergone the process of segmentation.

2. The parasite of the venous appendages of the Cephalo-

Bidder also allows no weight to the Author’s observations on the deve-
lopment of the muscular fasciculus (1. ¢.,p. 50), relying upon the untenable
law of continuity sought to be established by Reichert, and on the observa-
tions of Holst and Reichert (‘ De Structura Musculorum,’ Dorpat, 1846).
‘The Author, however, maintains his own opinion as the only true one, in
opposition to the Dorpat observers. Renewed investigations have shown
him that, in the chicken, in the mammalian embryo, and in the Batrachian
larva, in all alike, the whole muscular fasciculi originate in series of
cells, and that each of the widely separated fibrille originates in a series
of cells, and that they are simply modified cell-contents. This has been
recently confirmed also by Bendz, in the Vertebrata, and Leydig, in the
Annelida, With respect to the striped muscles, it is not uninteresting to
notice the occurrence in them of anastomoses, or branchings of the entire
fasciculus. ‘This may be observed in the fasciculi of the auricle of the
frog (fig. 6). In this case it will be found that here and there two fasciculi
are united by a transverse fasciculus, and that there exists not merely a
mutual application of separate fasciculi, but a continuous connexion, an
actual coalescence. The Sarcolemma of the three fasciculi in fig. 6, for
instance, forms three connected anastomosing tubes, and the primitive
fibrilla also pass apparently without any line of demarcation from the one
into the other, although it cannot be exactly said that they are actually
continuous in the three fasciculi, In the same way Dr. Leydig has
noticed very beautiful anastomoses and branchings of the striped muscles
in Piscicola (S. aud K., Zeitsch., B. i. p. 108). The author has no doubt
but that these anastomosing striped muscles, in part at least, originate
in stellate cells; in this case there exists a perfect analogy in the develop-
ment of the most important higher elementary tissues, inasmuch as that
they are all formed, in part by the coalescence of rounded or elongated, and
in part by the union, of stellate cells. he latter condition has hitherto
been observed in the capillary blood- and lymph- vessels in the termina-
tions of the nerves (S. and K., Zeitsch, B. i., p. 54) and in those of the
trachez in insects.

KOLLIKER ON ACTINOPHRYS SOL. 105

poda, which the author has named Dicyema paradoxum, in
which exactly the same condition is found to existas in Hydra
(vid. Kélliker’s Bericht ttb. d. Zootom. Anst. in Wiirzburg,
1849, p. 61).

(c.) Certain cells elongated into fibres in the higher animals
—for instance, the so termed muscular fibre-cells or the ele-
ments of unstriped muscle; which are to be regarded as
elongated cells, in which the membrane and contents are
united into a soft substance.

In this enumeration, all those parts of animals which have
been distinctly proved to possess a contractile property are
contained, and it is consequently apparent that all these parts,
taken in a general point of view, fall into but few categories—
viz. into two, contractile cell-membranes and motile cell-
contents. It is not thence, however, to be inferred that there
are but two kinds of contractile elementary tissue, much rather
must several such, more or less different, be admitted accord-
ing as the cell-membrane and its contents assume one form or
another,

Such an arrangement as the following appears to be most
suitable :—

Contractile elementary tissues are—

1. The amorphous contractile substance = a) a cell-con-
tents; 4) one or several cells with membrane and contents
united,

2. The spermatic filaments = the formed nuclear contents
of a cell.

3. The cilium = an out-growth of a cell-membrane.

4. The contractile vesicle = an entire cell-membrane.

5. The contractile tube = a number of coalescent cell-
membranes.

6. The contractile fibre-cell = an elongated cell with mem-
brane and contents united.

7. The contractile fibril-fasciculus (animal muscular fasci-
culus) = the contents of a series of coalescent cells, which are
metamorphosed into a homogeneous contractile tube (vid,
Leydig on ‘ Piscicola’).

If instead of the anatomical characters, the physiological
properties of the contractile parts are regarded, other
groupings of them naturally arise ; thus, for instance, 1, 2, 3,
and in which the movement is wholly independent of nerves,
and 5, 6, 7, in which it is effected by nervous influence, would
respectively be associated. Besides this, regard must be paid
to the relations of the contractile element, to galvanism, cold,
mechanical irritation, &c. This is a point, however, which
cannot be further entered upon in this place, and the author

106 SCHACHT ON THE MANTLE OF CERTAIN ASCIDIANS.

concludes with the expression of a wish that his readers may
deduce at least this, from his communication, that what is
simple enough in nature affords a key to what is compound,
and is therefore worthy of all consideration,

On the Microscopical and Chemical Examination of the Mantle
of certain Ascipians. By Dr. H. Scuacut. Miiller’s
Archiv, p.176. 1841.

(Continued from page 29.)

The above facts show, first of all, two things:—1. That
the cell-membrane in the mantle of Phallusia does not, as
stated by Kélliker and Léwig, consist of cellulose, but rather
that it behaves towards iodine and sulphuric acid, as well
as towards caustic potass, exactly like an animal substance
nitrogenous ; 2. That the homogeneous, or only in the second
layer, slightly fibrous interstitial substance, is composed of
tolerably pure cellulose.

In Clavellina Kolliker and Léwig found cells ina lamina of
the mantle, similar to those in Phallusia, also imbedded in an
interstitial substance; in the tunic of Salpa these cells are
wanting, the cellulose substance contains nuclei and crystals ;
in Pyrosoma, they found in the structureless tunic, only isolated
ramified cells; the structureless membrane of Diazona is
penetrated according to them by elongations of the fleshy tunic
of the animal. In the tunic of Didemnum, the same observers
again found cells, of which the membrane, though incrusted
with carbonate of lime, was soluble in boiling potass ; in
Aplidium they found similar cells in the interstitial substance,
and here also the membrane of the cells was soluble in the
caustic potass—only the interstitial substance remaining. In
Botryllus, according to them, the internal layer consists of
delicate fibres, which, like the rest of the homogeneous sub-
stance, in which nuclei and crystals occur, resist the action of
hydrochloric acid and of potass; the nuclei are soluble in
potass ; the crystals insoluble in acid; branched channels,
dilated at the extremity, which exist in this instance, are
regarded by K6lliker and Lowig as processes of the fleshy tunic,

[The author then details his experiments on the mantle of
Cynthia microcosmus, and proves the existence of cellulose in
it ina fibrous form, mixed with another substance soluble in
caustic potass, of which the outer epidermis appears to be
wholly composed. But whether the fibres are composed of
pure cellulose, and the second nitrogenous clement is simply

SCHACHT ON THE MANTLE OF CERTAIN ASCIDIANS. 107

deposited between them, or whether the latter also pervades
the substance of the fibres themselves, he is unable to deter-
mine. The cellulose, however, in Cynthia microcosmus
appears to differ in some respects from that in the tunic of
Phallusia mamillaris, inasmuch as it is coloured blue by
ioduretted chloride of zinc, which the latter is not.

In this part of his paper the author describes a mode of
procuring thin slices of very soft or yielding substances, by
including the latter tightly between two pieces of cork and
cutting thin slices of the whole with a razor. The structure
of the mantle in the undescribed Ascidian from Chili appears
to be very similar to that of the Cynthia last described.]
He then proceeds :—

Although the methods pursued by us respectively, were
very different, yet the results of my observations coincide in
great measure with those of Kélliker and Léwig. In only
one principal point do I differ from them: the membrane of
the large cells in the mantle of Phallusia 2s not composed of
cellulose. It behaves exactly like animal membrane, and is
probably nitrogenous, and would therefore represent the pri-
mordial sac of the vegetable cell, which exhibits precisely the
same chemical re-actions.

It seems to me that the observers just quoted had not seen
the membrane of these cells, indicated by the delicate folds
described above, as they adduce as a distinction between these
cells and those of a plant, the coalescence of their walls,
composed of cellulose, with the homogeneous interstitial sub-
stance. In Didemnum candidum, it is true, they observed
not only the membrane, but also that it was soluble in caustic
potass ; and consequently in this case it could not be composed
of cellulose. That I did not meet with isolated cells in the
mantle of Cynthia as Kolliker and Lowig did, does not surprise
me, those observers not having found a trace of sych cells in
the mantle of Phallusia gelatinosa, whilst in another specimen
they noticed nuclei and indications of these cells. It seems,
therefore, as if the latter belonged to a definite period of the
animal’s life.

Kolliker and Lowig at the end of their paper refer to the
history of the development of the embryo of certain Ascidians,
given by Milne Edwards; from which they conclude :—

1. That the external structureless tunic of the embryo after-
wards forms the mantle of the adult animal, consisting of
cellulose ; 2. That this tunic, which subsequently contains
nuclei, fibres, &Kc., is the product of the cells formed by the
segmentation of the yelk. They believe also that the mantle of
other Ascidians, which is perforated by vessels, as in Phallusia,

108 SCHACHT ON THE MANTLE OF CERTAIN ASCIDIANS.

is at first structureless, and in this condition is not composed
of cellulose, but that cells are formed in its substance which
multiply and secrete the cellulose; at a latter period, however,
themselves again disappearing. They also detected in the
stomach and intestines of Phallusia, Clavellina, and Diazona,
both the remains of Algz as well as Closteria [in salt water ?].
The cellulose, therefore, would seem to be introduced from
without ; in what way, however, it is separated from the blood,
in order to be secreted in certain parts of the body, remains
unexplained ; an accurate analysis, therefore, of the blood of
the Ascidians would be of great importance.

If, now, the occurrence of cellulose in the mantle of the
Ascidians above described, be compared with the conditions
under which the same element exists in the vegetable kingdom,
the following very essential differences are apparent :—

1. In the vegetable kingdom the cellulose constitutes the
so-called primary cell-membrane, and the thickening layers of
the cell deposited upon it. The vegetable cell-wall, consisting
of cellulose, is always separated from the wall of the neigh-
bouring cells, by an interstitial substance (intercellular sub-
stance) which is soluble in chlorate of potass and nitric acid,
On their being boiled, therefore, with caustic potass and by
maceration [in chlorate of potass and nitric acid] these cells
separate from each other ; but in the mantle of Phallusia no
such separation takes place, because there, the cellulose,
although probably distinct from the nitrogenous membrane of
the cells, itself constitutes the interstitial substance; the in-
tercellular substance of the plant being entirely absent.

2. The vegetable cell is thickened by the laminated deposit
of new cellulose in the previously existing layers of that
substance ; such a laminated structure, which is demonstrable
by proper treatment in all thickened vegetable cells, is alto-
gether absent in the cellulose of the mantle of the Ascidians.

3. In the vegetable kingdom the cellulose never occurs in
the form of free fibres, as in the mantle of Cynthia, &c.; the
band in the spiral vessels of plants, apparently composed of
a fibre, arises in the unequal development of the thickening
layers.

4. In the vegetable kingdom, the cellulose never appears as
a homogeneous substance, either between the cells or nuclei of
cells ; as is the case in the mantle of the Ascidians.

These differences in the mode of occurrence of the cellulose
are so essential, that it would seem to be impossible to con-
found an animal tissue containing cellulose with any vegetable
tissue whatever, |'lhe appearances exhibited in a section of
the stem of Laminaria saccharina, when treated with iodine

SCHACHT ON THE MANTLE OF CERTAIN ASCIDIANS. [09

and sulphuric acid, are adduced and figured by the author, as
a contrast to what takes place under the same re-agents in the
mantle of Phallusia. |

The chemical relation of the cellulose itself, however, in the
Ascidians examined by me, is not essentially different from
vegetable cellulose. Caustic potass has no effect upon either ;
sulphuric acid dissolves both; iodine and sulphuric acid
colour both equally, blue; ioduretted chloride of zinc induces,
it is true, in most vegetable tissues the same blue colour as
that produced by iodine and sulphuric acid; there are, on
the other hand, vegetable tissues (such as, in Fucus serratus,
Chordaria scorpioides, the wood-cells of Pinus sylvestris, &c.)
upon which the same re-agents produce no effect ; the iodu-
retted chloride of zinc appears generally to be less energetic
in its action than sulphuric acid. After they have been boiled
with caustic potass both the cellulose-substance of the mantle
of the Ascidians and the thickening substance of the so-termed
plant-cell are coloured blue or violet by the ioduretted chloride
of zinc solution, the potass probably in both cases removing
a material which prevented the action of the re-agent.

By maceration after Schultz’s method, the last-mentioned
material, in the Ascidians above noticed, is as little dissolved
as the cell-membrane in Phallusia, nor is it, in the vegetable
kingdom, always removed by the same maceration; the
thickening layers of the epidermis cells of several plants are
not coloured blue by ioduretted chloride of zinc after macera-
tion, whilst after boiling with potass that re-agent produces
the characteristic colour. The substance, therefore, in the
mantle of the Ascidians, soluble in caustic potass, appears to
be closely allied in its properties to the so-termed incrusting
substance of the vegetable tissue.

In the mantle of Phallusia, we have, as I have certainly
proved, both a homogeneous, interstitial substance composed
of cellulose, and also indications of fibres composed of the
same element ; besides which there are, in the interstitial sub-
stance and between the fibres, nuclei and cells, thus the same
elements as those which occur in Cynthia and the new species
from Chili; in the case of the Phallusia the cells are more
abundant, in the latter the nuclei and fibres; which seem
generally to accompany each other. In the fibrous part of the
mantle of Phallusia we find only nuclei, and no cells; in the
portion, again, which consists of cells, no fibres, and but few
nuclei. As in this case we are without any history of the
development of the tissue, no further conclusions can be drawn
respecting it,

Although, in the present state of science, the occurrence of

110 SCHACHT ON THE MANTLE OF CERTAIN ASCIDIANS.

cellulose does not suffice for a distinction between plants and
animals, yet the previously established law that the animal
cell-membrane always contains nitrogen retains its force. The
animal cell is in all cases, as far as I know, entirely different
from the vegetable cell. The intercellular substance is always
wanting in tissues composed of animal cells ; the animal cell
itself corresponds with the primordial sac of the plant-cell,
which also does not consist of cellulose, but is probably nitro-
genous, like the animal cell-membrane. Whilst the plant-cell
is thickened by the secretion of cellulose around the primordial
sac, and thus obtains the true cell-wall; the animal cell also
secretes a material—in the mantle of the Ascidians the same
cellulose—but this material does not form a special envelope
around the previously existing nitrogenous cell, the secretions
of the individual cells, owing to the absence of any intercellular
material, coalescing into one substance. In this way probably
is formed the interstitial substance composed of cellulose in
the mantle of Phallusia ; and in like manner the stroma of the
cartilaginous tissue, which is not composed of cellulose, and
the interstitial substance, impregnated with calcareous salts of
the osseous tissue. The want, therefore, of an intercellular
substance constitutes the principal distinction between the
animal and vegetable cellular tissues. Owing to this, the
animal cells, even in cases where cellulose occurs, never have
a wall composed of that substance, which is characteristic of
the vegetable cell. It is to be regretted that this diagnostic
character is wanting in the lowest unicellular animals and plants.

The existence of the intercellular substance has, it is true,
been very recently disputed, with respect to the plant-cell, by
Wigand (Intercellular Substance and Cuticula. Braunschw.
1850). That author has termed the true intercellular sub-
stance, which, so far as my most recent investigations extend,
is always present, the primary cell-membrane, whilst the
latter is not to be distinguished, either optically or chemically,
from the thickening layers of the vegetable cells consisting of
cellulose.

The resumé of my reseaches therefore may be thus given :—

1. In the mantle of the Ascidians there is a substance
insoluble in caustic potass, but soluble in sulphuric acid,
which is turned a beautiful blue by iodine and sulphuric
acid, and which consequently consists entirely of cellulose.
This substance constitutes the interstitial substance of the cells ;
in the mantle of Phallusia it is homogeneous, but in Cynthia,
&c., exists for the most part in a fibrous form.

2. The mantle of the Ascidians contains, besides this cellu-
lose, another material soluble in caustic potass, but insoluble

SIEBOLD ON UNICELLULAR PLANTS AND ANIMALS. 111

in sulphuric acid, and not coloured blue by iodine and sul-
phuric acid, and which consequently is not cellulose; in the
mantle of Phallusia it is only sparingly present, but in Cynthia
and the new Chilian Ascidian it is much more abundant, and
alone constitutes the corneous epidermis of their mantle.

3. The membrane of the cells in the mantle of Phallusia
does not consist of cellulose ; it is coloured brown by iodine
and sulphuric acid ; is soluble in caustic potass, and behaves
exactly like an animal membrane, as do the nuclei and vessels.

4. Inthe mantle of Phallusia cells abound ina homogeneous,
interstitial substance composed of cellulose ; it is only at the
inner margin of the mantle that fibres composed of cellulose,
with nuclei amongst them, make their appearance. In
Cynthia, &c., there are scarcely any traces of cells, whilst the
nuclei and cellulose fibres abound.

5. A tesselated epithelinm, containing no cellulose, covers
the inner surface of the mantle of the three Ascidians examined
by me; the outer surface of the mantle of Phallusia appears to
possess a similar epithelium.

6. There are two essential points of difference between the
modes in which cellulose occurs in the Ascidians and in the
vegetable king¢dom—1. In Phadllusia the cellulose constitutes
the intercellular substance, but does not, as in plants, form an
integral part of the cell-wall itself; 2. In Cynthia and other
species the cellulose forms free fibres, a form in which it is
never observed in the vegetable kingdom.

7. The substance of the mantle in the Ascidians is not dis-
integrated by boiling with caustic potass or by maceration with
chlorate of potass and nitric acid, like the vegetable cellular
tissue into its elementary parts; there is in it none of the
intercellular substance universally present in vegetable tissues,
and by which the cells are connected, but which intercellular
material is never composed of cellulose, as it resists sul-
phuric acid, but is soluble in caustic potass, as well as by
maceration.

On Unitcettutar Piants and ANIMALS. By .C. b- v.
SieBpoLp. From Siebold and Kdlliker’s Zeitsch. f. w.
Zool. Bd. 1,'p. 270.

In the first part of my work on the ‘Comparative Anatomy
of the Invertebrata,’ published in 1845, I have arranged the
Protozoa (Infusoria and Rhizopoda) as unicellular animals ;
thus separating them from a series of minute organisms, de-
scribed by Ehrenberg as Polygastric Infusoria, viz. the Clos-

112 SIEBOLD ON UNICELLULAR PLANTS AND ANIMALS.

terina, Bacillaria, and Volvocina, which I referred to the
vegetable kingdom. The limits of that work did not allow
me to adduce more than the most important reasons by which
I had been induced to come to this conclusion. I could well
foresee that in the publication of these views I should be
placed in direct opposition to Ehrenberg’s authority; an
authority so generally recognised. Ehrenberg had already
reproachfully said that I should have been more careful in
protecting science against new opinions respecting the or-
ganization of microscopic organisms, which are easily intro-
duced, but not so readily dissipated. I can assert, however,
that having for years entertained doubts as to the correctness
of Ehrenberg’s views as to the organization of the lowest
animals, I have not ventured to oppose so great an authority,
unless prepared by the assiduous study of the lower organ-
isms, and that the deeper did I enter into this inquiry the
deeper did my doubts, with respect to Ehrenberg’s views,
become rooted.

How very much disinclined I have been from the first to dis-
seminate lightly and incautiously, erroneous views in science,
is shown by the way in which I acted with respect to an error
[had fallen into, in the year 1836, and with which I was charged
by Ehrenberg in 1848, meaning me, when he says, without men-
tioning my name, “ the author of the new genus of an inch-long
double animal (Syngamus trachealis), which, after the publi-
cation of his correct anatomy of it, it was necessary for some
one else to remark is nothing but a pair of strongyli in the
act of conjunction, as he himself acknowledges.”—Wieg-
mann’s Archiv, 1837. This error, the moment I knew it, I
recanted ; so that it was not quite a year before the scientific
world. On the other hand, how obstinately does not Ehren-
berg adhere to the chain of delusions and errors in which he
has more and more closely involved himself from year to year.
In vain, hitherto, have other naturalists in Germany, on the
Seine, and on the other side of the Channel, endeavoured to
draw either Ehrenberg or his followers from their erroneous
ways, and to set them on the right path; and I will therefore
direct the attention of the latter to a voice, which, even from
the other side of the Alps, has made itself loudly heard in
opposition. Meneghini, of Pavia, seeking to prove the vege-
table nature of the Closteria and Desmidiacew, thus expresses
himself on the subject of Ehrenberg’s errors :—‘“‘ Cosa se ne
deve dedurre? Che anche il piu accurato osservatore e
’ uomo de genio possono errare. Ne cid potra mai scemarne
il merito, o rendere men importanti i benefizii ch’ egli rese
alla scienza, I] danno non ridonderebbe che su coloro, i

SIEBOLD ON UNICELLULAR PLANTS AND ANIMALS. 113

quali, schivi alla fatica dell’ osservare, si accontentano della
autorita del maestro et ne abbraciano indifferentemente, cosi
le vere scoperte come gli errori. Grazie al cielo |’ epoca del
autorita e tramontata, e chi ve si aggioga erri pure conpace,
che per questo la scienza non avyanzera meno, ed anzi da
quegli errori stessi essa potra trarre vantaggio.’’*

With respect to my views on the organization of the Pro-
tozoa, published in 1845, I have nothing in the main to recall ;
on the contrary, I have since then had the satisfaction of
knowing that recognised naturalists and distinguished micro-
scopists have already sided with me.

It is, moreover, highly gratifying to notice that at present
the study of the lower vegetable forms, which as unicellular
plants correspond to the Protozoa as unicellular animals, is
exciting a very high interest, and that these hitherto much
neglected organisms are now finding investigators among
the most eminent Botanists, by whose labours their position
in the vegetable world will eventually be decided.

As one of the most important of the works that have
appeared of late upon this subject, the following must be
indicated :—Néageli’s ‘Genera of Unicellular Alge, physi-
ologically and systematically considered.’}.

I believe it will not be without interest if I here notice the
more important points in which, according to Nageli’s re-
searches, the unicellular Algz are distinguished from the
lower animal forms. As especially worth consideration, I
would adduce the following expression of Nageli’s (p.2):—“ It
is to be lamented that of several genera and of many species of
hitherto known unicellular Algz nothing has been observed
respecting their propagation, and that consequently not only
has their systematic position but even their independence as
unicellular plants remained in doubt.” I am satisfied that
many of Ehrenberg’s Infusoria, were their origin and de-
velopment, as well as their modes of propagation, fully traced,
would long since have been recognised as vegetable forms ;
that is to say, as lower forms of Alge. _

For the better appreciation of the exposition given by
Niageli respecting the organization and vital actions in the
unicellular Alga, with reference to the vegetable forms con-
sidered as Infusoria by Ehrenberg, it will be necessary to
premise a list of those vegetable organisms which have been
treated by Ehrenberg as Infusoria, and by Nageli as uni-

* G. Meneghini. Sulla animalita delle Diatomee. Venezia, 1846,
p- 172.

+ Gattungen einzelliger Algen physiologisch und systematisch bear-
beitet von C. Nageli (Zurich, 1849, mit 8. lith Tafl.).

VOL. I. I

114 SIEBOLD ON UNICELLULAR PLANTS AND ANIMALS.

cellular Algae. Among the eight orders of unicellular plants
instituted by Nageli, that of the Curoococcace# contains, in
Meyer’s genus Merismopeedia, Gonium ylaucum, tranquillum
and punctatum, Ehr. The order of the DsatomacEz# cor-
responds to the siliceous Bacillaria, Naviculacea, Echinellea,
and Lacernata, Ehr. In Nageli’s order of the Patmet-
LACE we find Arthrodesmus and Tassarthra, Ehr., referred to
Scenodesmus, Mey.,as well as the genus Micrasterias, Ehr.. to
Pediastrum, Kiitz. Lastly, the order DEsmipiacEz contains
many unicellular Alge, placed by Ehrenberg under the
genera Desmidium, Pentasterias, Euastrum, and Closterium.
For part of these Ehrenberg’s definition is retained; but
others of them are raised to the rank of distinct genera. Thus
has Nageli from Closterium trabecula, Ehr., formed the genus
Pleurotenium, and from Closterium cylindrus, Ebr., the genus
Dysphinctium ; whilst a portion of the Desmidez with Pen-
tasterias have been placed under the genus Phycastrum, Kiitz.

According to Nageli (p. 3), the unicellular Algze occur

either solitary or united into colonies, which readily break up
into single cells ; or they may be firmly united by a gelatinous
envelope, though separated from each other by a gelatinous
s ubstance, and without any organic connexion; or they are
placed singly at the extremities of a branched gelatiniform
peduncle. Occasionally, also, the cells are firmly connected
into a parenchyma, as in multicellular plants, in which case
the connexion breaks up into smaller portions, or even into
single cells, either not at all or but very seldom.

With regard to the relation of the unicellular Alge to the uni-
cellular animals, and the unicellular condition of multicellular
animals, Nageli(p. 4) thus expresses himself. ‘‘ The most im-
portant difference :—that the vegetable cell-membrane contains
no azote, whilst the animal cell-membrane does—cannot be ap-
plied, especially in doubtful cases ; the tenuity of the membrane
not allowing of the investigation, That animals possess the
power of locomotion but plants not, is, in the first place, in-
correct, as applied generally, and also here the less admits of
application, becaus@ many unicellular Algz exhibit motion, fre-
quently very energetic motion (when swarming), whilst the ova
of multicellular animals are quiescent. The unicellular Alge
differ from the Infusoria in this, that their membrane and its
appendages are not motile, and that consequently they have a
rigid form, whilst the latter, in some instances, change their
figure, and in others are furnished with motile-cilia. The
presence of starch in the cell-contents is, further, invariably
decisive as to the vegetable nature of a cell. The ova of
multicellular animals, the figure of which is rigid and un-

SIEBOLD ON UNICELLULAR PLANTS AND ANIMALS. 115

changeable, may also be recognised as not belonging to the
unicellular Alge from the want of colouring matter, which is
present in all the latter.” I shall have an opportunity further
on of recurring to several of these points, and of entering
more particularly into them.

As respects the chemical relation of the cell-contents of
unicellular Alga, Nageli lays great stress upon the presence
of colouring matter. This colouring matter is distinguished
by him as Chlorophyll, Phycochrom, Erythrophyll, and Diatomin.
The Chlorophyll is of a grass or yellow-green colour, little or
at all affected by diluted acids and alkalies, and frequently turns
brownish-green upon the death of the plant.* The Phycochrom
is verdigris-green or orange, changed into orange by the action
of diluted acid, and into a brown-yellow by that of diluted
alkalies. The Erythrophyll presents a red or purple colour,
not changed by diluted acids, but becoming green on the
addition of alkalies, and also most usually after death. The
Diatomin is brownish-yellow, not altered by diluted alkalies,
but changed into verdigris-green by diluted hydrochloric
acid, and, for the most part, by death. Together with the
colouring matter, continues Nageli (p. 9), starch grains, or
colourless oil-drops, are frequently formed, with the increase
of which in the persistent cells (dauerzellen) the former
finally disappears. '

I must here remark, that we can scarcely expect chemistry
to decide what is animal and what plant, having several times
been deceived in our hopes in this respect. The non-nitro-
genous cellulose, which at first sight appears to be an exclu-
sive attribute of the vegetable, also occurs pretty generally
disseminated in the animal kingdom, as we learn from the
researches of C. Schmidt on Cynthia mamillaris, and those of
Kolliker and Lowig on a great number of the most various
of the lower animals. Just as little does Chlorophyll ap-
pear to be exclusively characteristic of the vegetable world,
since the green granules and vesicles, which occur imbedded
in the parenchyma of Hydra viridis, of various Turbellariz
(Hypostomum viride and Typhloplana viridata, Schm.), and
of Infusoria (Euglena viridis, Stentor polymorphus, Bursaria
vernalis, Luxodes bursaria, &c.), are probably closely allied to
Chlorophyll, if not identical with it. Erythrophyll also
might be said to occur in the lower animals, for instance, in
Leucophrys sanguinea and Astasia hematodes, in which latter
the red colour frequently passes into green, as does the Ery-

throphyll of unicellular Algz.

* Vide Cohn.

116 SIEBOLD ON UNICELLULAR PLANTS AND ANIMALS.

Another more important circumstance connected with the
chemical composition of the cell contents, is also noticed by
Niageli, and which relates to the so called red eye-spot of certain
Infusoria. He saw, for instance (p. 9), in the midst of the
Chlorophyll of certain unicellular Algz, one or several bright
red or orange-coloured oil-drops, upon which he remarks upon
the similarity of these red granules with the red point, which
occurs in several swarm-spores, for instance in Ulothrix.
An inspection of Néageli’s Pl. 1V., B. fig. 1-4, will at once
show the identity of the bright red oil-drops in the quadran-
gular unicellular Algae Polyedrium trigonum, tetragonum,
tetraedricum, and lobulatum, Nag., as well as in the interesting
new unicellular Algwe, Ophiocytium majus, Nag. (Pl. 1V., A.
fig. 2), with the points, so often stated to be eyes by Ehrenberg.
These are precisely the same red points, as those which
are met with also in Eudorina, Chlumidomonas, and Volvoxr
Infusoria—which I must declare to be unicellular Alge.
Very remarkable is Nageli’s statement (p. 9), that the chloro-
phyll in many unicellular Alga occasionally disappears
altogether, being transformed into a red or orange-coloured
oil, a change not always connected with the death of the cells,
as for instance in Pleurococcus miniatus, Nag. ; Protococcus
nivalis, Kiitz.; Palmella miniata, Leibl., &c.

In almost all the genera in which chlorophyll occurs Nageli
found (p. 11) one or more chlorophyll-cells, for the most part
in regular number and disposition, and exhibiting the appear-
ance of granules or even of nuclei. Nageli satisfied himself
that these chlorophyll-cells, even from external appearance, are
the same forms as those which occur in the multicellular algze
containing chlorophyll, such as Zygnema, Spirogyra, Sphero-
plea, Conferva, &c. Further investigation perfectly assured
him of their identity. These chlorophyll-cells at first con-
tained only chlorophyll (that is, mucus coloured by chlorophyll)
with a delicate membrane. But they seldom remain in this
condition, starch at a subsequent period becoming developed
in them, by which the chlorophyll is wholly or in part dis-
placed. Then there either lie in the chlorophyll-cell one or
several minute starch-grains, or it becomes almost entirely filled
with starch, as happens in the Palmellacee and Desmidiacee.
From this it follows that, although the presence of starch,
as Nageli says, is decisive as to the vegetable nature of a cell,
this important means of diagnosis does not always admit of
application, because starch is not found in all stages of the de-
velopment of those plants which might be confounded with
unicellular animals,

But to return to these chlorophyll-cells—is it not apparent

SIEBOLD ON UNICELLULAR PLANTS AND ANIMALS. 117

that they are the bodies described by Ehrenberg as the testes ?
To perceive this it is only necessary to compare the various
figures in Niigeli’s work with Plates X. and XI. of Ehrenberg’s
great work, in which Scenodesmus, Mey., is figured as Arthro-
desmus and Tassarthra, and further Pediastrum, WKiitz., as
Micrasterias. The colourless hollow spaces filled with water,
observed by Nageli (p. 91, 95, Kc.) in the above named, as
well as in many other unicellular Algae, bave been regarded as
gastric cells by Ehrenberg, as is obvious at the first glance,
whilst the green granular Chlorophyll contents of these vege-
table organisms, according to Ehrenberg, would have to be
regarded as ova. In various Desmidiacew, for instance in
Pleurotenium, Calocylindrus, and Closterium, Nageli noticed
several Chlorophyll-cells, frequently arranged in a serial man-
ner. In Closterium digitus and Moniliferum, as well as in some
other Closteria, he observed in the centre of the cell a clear
nuclear-yesicle with an opaque central nucleolus. It is these
chlorophyll and nuclear cells which Ehrenberg and Eckhardt
would arbitrarily explain sometimes as a polygastric apparatus,
sometimes as the male glandular organs of the Closteria.

The cell-wall in the unicellular Algae, according to Nageli
(p. 12), exhibits in respect to colour, conformation, and sub-
stance, the greatest variety. Very frequently it possesses a
considerable thickness, and in this case may be regarded as
laminated, the innermost very delicate layer representing the
true cell-membrane, whilst the external thick layer, more or
less distinctly defined on the outer side, constitutes an enve-
lope for the cell. This enveloping membrane consists of
vegetable gelatine in various stages of condensation. It may
surround each individual cell, or contain 2, 4, 8, &c. together,
or even a whole aggregation of cells, as an entire family or
colony. As forms of Algz furnished with a gelatinous enve-
lope I may adduce Gonium, Schizonema, Naunema, and Syncy-
clia, Ebr.; to which must be added Eudorina, Spherosyra,
Chlamidomonas, Pandorina, and Volvox, Ebr. In some cases
the lamination and thickening of the envelope takes place only
on one side, whence it assumes the form of a peduncle, at the
extremity of which the cell is placed, owing to which, when
longitudinal scission of the cells takes place, a branched pe-
duncle is produced. With reference to this compare the figures
of Synedra, Achnanthes, Echinella, Cocconema, and Gompho-
nema, Ebr. Frequently also the cell-membrane exhibits thick-
enings, which are sometimes placed towards the interior (in
the Diatomacez), sometimes towards the exterior (in Euastrum
and Closterium).

The growth of the unicellular Algae, according to Nageli,

118 SIEBOLD ON UNICELLULAR PLANTS AND ANIMALS.

takes place, either with a general expansion of the cell-mem-
brane or with a unilateral, or point-growth as it is termed.
The propagation of the unicellular Alge (p. 17) is effected in
very various ways, by division, by conjugation, by free cell-
formation, and by abscission of segments, with various modi-
fications. Of these various modes of propagation discussed
by Nageli, I will only observe upon those which have refer-
ence to the Algz described by Ehrenberg as Infusoria,

In the mode of propagation by scission the entire cell-con-
tents, according to Nageli, become individualised into two
(rarely four) parts. After the formation of these filial cells the
mother-cell ceases to exist. Nageli here adduces, as an example,
the propagation of the Palmellacez (to which belong several spe-
cies of Gonium, Ehr.), the Diatomacee and Desmidiacee. In
Euastrum, after the scission has taken place, in each filial cell
the one half is perfected entirely anew, whence in the younger
condition this new half is small, almost spherical and colour-
less. Ndageli has shown this mode of propagation in Euastrum
margaritiferum, Ebr. (p. 118, Tab. VII. A, fig. 2, e); whilst
we had previously a description of this interesting process of
division and growth in Staurastrum and Euastrum, by Ralfs
(Ann, Nat. Hist., vol. 14, 1844, Pl. VI, VII., and vol. 15,
1845, Pl. X., XII.) and Focke (Physiol. Stud., Bremen, 1847,
p- 47, Pl. IL).

Propagation by conjugation occurs in the Desmidia-
cee, which Nageli (pp. 17, 18, Tab. VII, A. fig. 64) thus
describes, in Euastrum rupestre, Nag. :—Two individuals are
placed close together, and push out short processes, which
meet, and by the absorption of the wall constitute a canal, into
which the entire contents of the two cells thus connected
enters, constitutes one mass, and is gradually formed into a
single cell. Néageli adds, however, that in Closterium this
act of conjugation proceeds in a different way, which I can
confirm. In Closterium lunula, according to Morren (Ann.
d. Se. Nat., tom. V. 1836—Botanique, p. 325, pl. 9) the con-
jugated individuals appear to grow together exactly in the
way above described ; in Closterium rostratum also, two indi-
viduals appear to become united by the middle of their body
(Vid. Focke, |. c. pl. Ill. fig. 34-36, and Ralfs, Brit. Desmi-
diew, 1848, pl. XXX. fig. 3¢); whilst Closterium Diane,
lineatum, striolatum, setaceum, &c., behave in a totally different
manner in this process. In these species the middle of the
cell-membrane dehisces with a transverse fissure, and the
entire contents, from two contiguous, opened cells, coalesce
into a single rounded or angular mass. Sometimes (in Closterium
lineatum) it is only the two upper and lower halves which thus

SIEBOLD ON UNICELLULAR PLANTS AND ANIMALS. 119

coalesce, forming two closely approximated compressed glo-
bule&. Relatively to this mode of conjugation I refer to the
representations given in Ehrenberg, pl. V. and VI., as well as
in Ralfs, pl. XXIV. to XXX. It remains to be inquired
whether the green bodies produced by this conjugation, the
covering of which, at first very delicate, gradually becomes
thickened, are to be regarded as spores or as sporangia. I
have not myself been able to observe what proceeds from the
green bodies in course of time. According to Morren (0. c.
p- 329, pl. 10), however, it would appear that in Closterium
lunula the green spores arising from the conjugation grow
into a new Closterium after they have emerged from their
envelope and, like the spores of Vaucheria, move about freely
in the water. This process, as is truly remarked by Focke
and Nigeli, is not in any way one of multiplication, but pro-
perly a kind of reduction or diminution. I suppose, there-
fore, that the green bodies produced by the conjugation are
not in all cases developed into a single Closterium, like spores,
but that, as in the case of other Algzw, such as Vaucheria,
(£dogonium, there are two sorts of spore formations, and that
under certain circumstances these green bodies represent a
germ—capsule or sporangium—in which, by a process of divi-
sion, several young Closteria come to be perfected. With
this mode of development, probably, is connected the vesicular
body, containing sixteen small Closteria, figured by Ralfs
(pl. X XVII.) as belonging to Closterium acerosum. Accord-
ing to Jenner (ib. p. 11) the covering of the green bodies in
Closterium, which are regarded by Ralfs as sporangia, swells
whilst a mucus is secreted within it, and minute Closteria are
formed, which at last, by their increase, rupture the attenuated
vesicular covering. Whether or no that form of gelatinous
vesicle, containing eight young Closteria, which, according to
Focke (op. c. p. 57, pl. III. fig. 27), proceeds, in Closterium
digitus, from a process of envelopment, belongs to this category,
I will leave undecided.

Ehrenberg has proposed (0. c., p. 89) to designate these green
bodies of the Closteria, produced by conjugation, as double
buds, and the entire act of conjugation as a double gemmation.
This designation, however, is quite inapplicable, since in any
form of gemmation it is impossible that the entire contents of
a cell, as is the case here, should germinate into the new-
formed bud. Ehrenberg, moreover, in the exposition of the
organization and vital processes of the Closteria, perceived their
similarity with those of the Zygnemacee (Zyguema, Spirogyra,
Zygogonium, &c.), which are also propagated by conjugation.
He says (0. ¢., p. 99) that were any one readily disposed to

120 SIEBOLD ON UNICELLULAR PLANTS AND ANIMALS.

look for similarities, it would be easy to speak of vesicule
seminales, oviducts, and testes (in Spirogyra): but alk is
motionless ; and just as motionless is everything in the Closteria.
All those particulars, which, according to Ehrenberg, would
serve to prove the animality of these organisms, either have no
existence at all or are of no validity. He adduces four princi-
pal characters especially (7. c¢., p. 88), which would exclude
the Closteria from the vegetable kingdom.

1. They have spontaneous motion. The slow, turning, and
at the same time rare movements of the Closteria, present
no character of spontaneity ; these motions are certainly merely
the consequence of an active endosmosis and exosmosis, by
which the water immediately surrounding the Closteria, and
consequently themselves, are put into motion. 2. That they
have an opening at each end. But these openings have not
been seen by any other observer; the sharp-sighted Focke
(0. ¢., p. 95, 60), even, has been unable to perceive any. That
Eckhardt (0. ¢., p. 211; p. vii, fig. 1, rr) should have intro-
duced these openings into his figure of Closterium acerosum—
although they have not been observed in that instance, either by
himself or by Ehrenberg—can decide nothing. 38. That they
are furnished with conical, wart-like organs, projecting even from
these two openings, which are in continual motion; but these
organs, also, have not been discovered by any other observer.
According to Ehrenberg, the number of these proboscis-like,
motile organs is easily computed, since their basal portions, in
the form of minute, continually moving papilla, may be dis-
tinctly seen and counted in almost all Closteria. These papille,
however, are nothing else than quivering masses of granules,
in molecular motion, contained in two vesicular spaces. 4.
Lastly, Ehrenberg refers to the transverse division observed in
the Closteria, which, according to him, is to be indisputably
regarded as irreconcilable with the vegetable character. That
Ehrenberg is here altogether in error, will be admitted by
any one who has at all studied the lower vegetable world.
The Closteria, therefore, are not only as rigid as the Zygne-
mata, but have quite as much right to be regarded as belonging
to the vegetable kingdom. No part of their body possesses
that contractility and expansibility which is an attribute of the
animal body alone. The progressive motion of granules and
fluids, which has been noticed in Clsoterium by Meyen,
Dalrymple, Lobarzewski, Focke, and Ralfs, does not proceed
from any contractile part of the Closterium cell, but corre-
sponds much more with the circulation exhibited in other
plant-cells, as in Chara, Vallisneria, and the hairs of the Nettle,
&e, But whether this motion of the fluids depends upon an

SIEBOLD ON UNICELLULAR PLANTS AND ANIMALS, 121

internal ciliary investment, as asserted by Focke (0. ¢., p. 56),
I may be allowed to doubt, as I have never been able to per-
ceive such cilia in the Closteria; and my friend A. Braun,
whose opinion on such a matter is of the utmost value, has
been equally unsuccessful. Since the Closteria, as well as the
rest of the Desmidiacex, are certainly plants, it follows that
conjugation, or zygosis, as a special kind of propagation, does
not belong to the animal kingdom, unless Kdlliker’s observa-
tion, of the coalescence of two individuals of Actinophrys Sol,
should be regarded as an analogous process. There is nothing
contradictory in the notion that such a conjugation should
exist in Actinophrys Sol, a protozoon of so simple a kind,
whose structureless body, according to Kélliker’s late researches,
consists of a homogeneous, contractile substance, without
mouth, intestine, or other organs. I would, on the other hand,
ask those who, with Ehrenberg, not only regard the Closteria
as animals, but are, besides, under the erroneous impression
that these creatures possess a very complex, motile apparatus,
polygastric digestive organs, male and female sexual organs—
I would ask them what becomes of this motile apparatus,—of
the various stomachs, ovaries, and testes,—when all these parts,
with the rest of the contents of the two cases which enclose
these so-termed complete animal organisms, have coalesced in
the act of conjugation ?

A third mode of propagation, viz. a free cell-formation, in
which the contents of the mother-cell are employed as a nutri-
tive material, in the formation of the filial cells, and, conse-
quently, in which the death of the mother-cell is involved,
would appear, according to Nageli (p. 17), to be restricted to
the orders of the Protococcacee and Valoniacez. Whether such
a production of filial cells within a mother-cell does not occur
in certain Palmellaceze and Desmidiacexe, which have been
confounded with Infusoria, | must leave as doubtful.

[To be continued. ]

( 122°)

RE VA Eas

LecruRES ON HISTOLOGY, DELIVERED AT THE RoyAL COLLEGE oF SUR-
GEONS OF ENGLAND, IN THE Session 1850-1. By JoHN QUEKETY.
London, Bailliére.

[Second Notice. }

Want of space compelled us to defer further notice of Professor
Quekett’s work in our last number. We shall now make a
few remarks on that portion devoted to animal histology.
Those who are less acquainted with vegetable than animal
tissues will wonder that a larger proportion of this work is
devoted to plants than to animals. We have already stated
our opinion that the best introduction to the study of animal
cells is the study of the cells of plants, and we think in a
limited course Mr. Quekett has done wisely in thus dwelling
on the simpler forms of organization. Having said so much
upon the vegetable histology, our remarks must be rather illus-
trative than critical on the remaining portion of this volume.
The following table will serve as a guide to the subjects

treated in this department :—

EXAMPLEs :—Walls of cells. Pos-
terior layer of the cornea. Cap-
sule of lens. Sarcolemma of
muscle, &c.

White and yellow fibrous tissues.
Areolar tissue. Elastic tissue.

Cartilage. Adipose tissue. Pig-
ment. Grey nervous matter.

Rudimentary skeleton of inverte-
brata. Bone. Teeth, &c.

“1, Simple membrane: employed alone
or in the formation of Te as
membranes

Fibrous tissues .

. Cellular tissues .

EEE a

Sclerous or hard tissues .

Mucous membrane. Serous and
synovial membranes, ‘True or
secreting glands,

of simple membrane, and a layer
of cells of various forms (epithe-
lium or epidermis), or of areolar
tissue and epithelium

6. Compound tissues: a, composed of
tubes of homogeneous membrane
containing a peculiar substance
b. Composed of white fibrous tis-
sues and cartilage

5. Compound membranes : ee
| Muscle. Nerve.

} Fibro-cartilage,”

The descriptions given of the structure of membrane, of
areolar tissue, and of yellow fibrous tissue, are all good, and
contain many original observations. The structure of the
various forms of cartilage is also described with great accuracy.
There is now no question as to the non-vascularity of these
tissues, but in a state of disease, the blood-yessels by which

QUEKETT’S LECTURES ON HISTOLOGY. 123

they are surrounded increase in size, and render them what
are called vascular.

“In a specimen from a diseased joint, which after removal was carefully
injected, numerous vessels may be observed passing through the cartilage ;
they are derived from the vessels of the shaft, as the articular lamella
being involved in the disease, permits the vessels to pass through it; they
proceed in straight lines through the cartilage to the free articular surface
upon which they form a network, and anastomose with others probably
derived from the synovial membrane. The subject from whom this spe-
cimen of cartilage was obtained was fifty years of age, and the disease had
existed for nearly twelve months. <A preparation which belonged to the
late Mr. Liston, and which he was in the habit of exhibiting in his Lec-
tures, consists of the head of the tibia, with diseased cartilage attached.
Not only can vessels be seen by the naked eye, passing from the bony
shaft into the cartilage, in the form of loops, but a rich network may in
some cases be observed upon a large portion of the articular surface. As far
as I have been able to learn from examinations of diseased articular carti-
lages, especially those affected with ulceration, I conclude that the change
first takes place in the cartilage cells, as is made evident by their becoming
rounder and much larger in size, and by their contents assuming a different
character, the nuclei disappearing, and globules of oil taking their place.
In some cases these oil-globules are of very minute size, and the cells then
appear granular; as the disease goes on, the cell-walls are absorbed, a
series of cavities are formed, all the hyaline substance in the neighbour-
hood becomes more or less fibrous, and ultimately blood-vessels are deve-
loped in the fibrous tissue.”

There is a series of valuable observations on Enchondroma.
In order to explain this structure he gives an account of the
structure. Speaking of the different views entertained on the
formation of the lacuna, he says—

With regard to the formation of the lacunze of bone, two views are
now entertained by different histologists. The first is that given in the
‘Physiological Anatomy’ of Professors Todd and Bowman, in which it is
stated that the lacune are developed from the nuclei of the cartilage-cells :
the other that of Mr. Tomes, published in ‘ Todd’s Cyclopedia,’ article
, Osseous Tissue,’ in which it is asserted that the lacune are not deve-
veloped from the nuclei of the cartilage cells, but are cavities left in the
newly formed bone, from which canaliculi are subsequently developed.
The last described specimen of enchondroma, however, tends to prove that
the view entertained by Todd and Bowman is the more correct.

Of softening of the bones he says—

In Mollities ossium, there is a deficiency of the earthy constituent of the
bone. The change first begins in the lacune, which become larger and
larger, and the bone around them more and more transparent ; finally,
several lacunz unite to form one cavity, which, however, does not long
remain empty, but is occupied by a soft kind of adipose tissue, so that
such bones are always extremely thin and full of fat. For this reason,
Mollities ossiwm may be considered as an example of the fatty degeneration
of bone.

Of all the subjects to which the attention of the morbid
anatomist has been directed of late years there is none per-
haps of more practical importance than that of fatty degenera-
tion, more especially of the muscular tissue. We are chiefly

124 QUEKETT’S LECTURES ON HISTOLOGY.

indebted for our knowledge of this condition of the muscular
tissue to the labours of Dr. Ormerod and Dr. Richard Quain.
Mr. Quekett gives a good account of this morbid condition,
and previous to doing so describes the structure of healthy
muscular tissue. The following is his account of the
fasciculi :—

The fasciculi exhibit transverse and longitudinal stri#, but, in most
cases, the former are more plainly exhibited than the latter. In some
animals the fasciculi break up transversely, in others longitudinally, so
that, in the one case, we have a series of discs, and in the other numerous
filaments termed fibrillea. The fasciculi of the eel readily break up into
discs, whilst those of man and most mammalia commonly separate into
fibrille. If the flat surfaces of the discs be examined, they present a
granular aspect, which is due to their being made up of the ends of the
fibrille ; and, if the fibrille be viewed with a power of five hundred
diameters, each one will exhibit a beaded structure, the part forming the
bead being a minute portion of muscular substance, termed myoline ; but
if the power be increased, the masses of myoline will be found to be sur-
rounded by a thin cell-wall. In the muscular substance of the eel, the
structureless sarcolemma surrounding a fasciculus is readily seen.

This we believe to be a true account of the muscular tissue,
and we cannot imagine that an unprejudiced observer, with a
good instrument, could contort the square masses of myoline
into a spiral form. Such, however, is the result of some
recently published researches, On the diseased condition Mr.
Quekett remarks :—

“Before fatty degeneration commences in voluntary muscle, the trans-
verse stria: disappear; and I have long known that the first trace of this
disease is marked by a disturbance of the particles of myoline, which
appear as so many very minute granules scattered irregularly within the
sarcolemma, leading one to suppose that the delicate cell around each par-
ticle had given way, thereby allowing the myoline to escape, and destroying
all regularity both of the transverse and longitudinal markings. As the
disease progresses, the myoline is replaced by minute, highly-refracting
globules of oil, until at last the whole sheath is full of them.

In a specimen of this diseased condition of muscle from the human
subject, the transverse striz are visible in the upper part, and a partial
disturbance of the myoline in the lower; in another preparation the
disease has so far advanced that all trace of striz# is completely lost, and
globules of oil, in this case of nearly equal size, but in others of variable
diameter, occupy the sarcolemma. ‘The fibres of the heart are very sub-
ject to fatty degeneration, and for our knowledge of this disease we are,
in a great measure, indebted to the labours of Dr. Ormerod; but the sub-
ject has been lately investigated with great care by Dr. Richard Quain ;
and in his paper, published in the fifteenth volume of the ‘ Medico-
Chirurgical Transactions,’ you will find all that is at present known
respecting it. A very excellent example of fatty degeneration of the
muscular fibres of the heart, is one taken from a man a hundred and three
years of age, for which I am indebted to the kindness of Dr. Edward
Smith ; it exhibits the transverse strie# in some parts, but in others these
are replaced by highly-refracting globules of oil. I have lately had the
opportunity of examining a most interesting case, in which the disease
was present in the voluntary muscles of the extremities. In one family

QUEKETT’S LECTURES ON HISTOLOGY. 125

of nine children, six of whom were girls and three boys, all the girls
were perfectly healthy, but the boys, on arriving at the age of three or
four, began to lose the use of their limbs. One of them, the eldest, has
lately died, and, on examination of the brain and spinal chord, both were
found to be healthy ; the muscle, however, had not only undergone fatty
degeneration, but the fasciculi themselves were much diminished in size,
which would, of course, account for the want of power in the limbs. This
disease from the first was supposed to be seated in some part of the ner-
vous system, probably arising from imperfect innervation of the muscle ;
but the discovery of its real seat will, it is to be hoped, lead to such a
mode of treatment as may be beneficial to the two afflicted survivors.”

We have yet to discover the causes of this terrible condi-
tion of the tissues of the human body. That it is brought on
by want of action in the muscles is shown by its vccurrence
in paralysed limbs and in those muscles of animals which do
not perform their normal functions. The most fearful seat of
its attacks is the heart: when once it seizes this organ its
action is impaired, and frequently sudden death is the result.
In this case it is probable that the blood is first at fault and
leads to the abnormal nutrition of the muscular fasciculi.

In the section on adipose tissue we find a statement of
some interest.

“Tn all works on anatomy and ohystfezy, even of so late a period as
last year, it is distinctly stated, that adipose tissue exists in invertebrate
animals; this, however, I find to be incorrect, and it cost me no small
amount of labour to prove it. Fat certainly does exist in insects, crus-
tacea, and mollusca, but no true adipose cell is ever present; it could not
be nourished without its accompanying blood-vessels, and these are not
found in invertebrata. The tissue resembling adipose tissue usually be-
longs to the liver or other glandular organ, and the fat exists in its cells
in the form of oil.

In the liver of the larva of a goat moth, Cossus ligniperda, which con-
sists of a series of cells or vesicles, containing a large number of globules
of oil; and again, in another specimen, taken from a cockroach, there are
tubes, also full of oil globules, but in neither case, and not even in the
Cephalopoda, is the oil contained in adipose cells.

As soon, however, as we pass the barrier between the invertebrate and
vertebrate sub-kingdoms, we find that even in the lowest members of the
class of fishes, true adipose cells occur, and all are doubtless aware, that
in the liver of the cod, and of many cartilaginous fishes, fat exists in the
form of oil without any adipose tissue ;—in this particular, the liver
resembles that of an invertebrate animal.”

The almost universal presence of oil in the tissues of animals
is an interesting fact, and one the full import of which is not
perhaps at present well understood. We have here a fruitful
subject for microscopic research.

But we must conclude. The publication of these lectures
will make all who are interested in microscopical investiga-
tion anxious for further remarks from Mr. Quekett. At pre-
sent he has only given the outlines of histological inquiry, and
much is to be expected from one who so honestly observes and

126 REPORT OF PATHOLOGICAL SOCIETY.

gives his opinions. In our notice we have omitted all refer-
ence to the wood-cuts which accompany the volume, but they
are very numerous (159 in number), well executed, and all
original. It is not often nowadays that one gets such a stock
of new matter to drawupon. All those interested in histology
will be glad to have this volume in their library.

REPORT OF THE PROCEEDINGS OF THE PATHOLOGICAL SocreTY oF LonpoN.
Sixth Session, 1851-1852.

Tue number and value of the contributions to microscopic
pathology in this volume of Reports of the Pathological Society
are such as fully to justify a notice of it in our Journal. These
contributions constitute, in fact, a main feature and no little
part of the book, and add very materially to its interest and
utility. Their number shows the extent to which microscopi-
cal investigations of the highest practical importance are carried
by the rising generation of medical men; and the manner in
which they have been carried out, as displayed in this volume,
is a most satisfactory proofof the technical skill and care of
the observers. It is clear that the gross and coarse pathology
of former periods, as well as the kindred physiology and
anatomy of the same times, is rapidly and effectually giving
way to the more refined analysis for which the microscope, in
its improved and still improving form, affords the means.

Amongst the more generally interesting and valuable of
these contributions we have only space to refer, and that briefly,
to a few.

From Dr. W. Jenner we have “An Account of Crimson or
Hematoid Crystals,and Calcification of the Minute Arteries of the
Cerebrum” (p. 239) ; “A Description of a case of Cancer in the
Posterior Mediastinum” (p. 255); “ Of avery curious case of
what is here termed Colloid Disease of the Abdominal Viscera”
(p. 823). Of the microscopical appearances in this case a
very careful and detailed account is given. Among the inter-
esting points, Dr. Jenner refers to the close resemblance of
certain phosphate of lime granules to olein, and to the
resemblance borne by the fat imbedded in the colloid matter
to cells. He directs attention especially to the close resem-
blance—a resemblance so close that he could give no visible
characters whereby the one may be distinguished from the
other—between the phosphate of lime and fat. These globules,
which, judging from the eye alone, experienced microscopists
pronounced to be oil, were dissolved completely in hydro-
chloric acid. He conceives that the phosphate of lime was

REPORT OF PATHOLOGICAL SOCIETY. 127
deposited chiefly in the interior and nuclei of the epithelial
scales lining the imner surface of the cells or cysts in which
the colloid matter was contained. A very nearly similar report
on the same case is given by Dr. R. Quain. From Dr. Jenner
we have also a “ Report on the Microscopic Appearances in a
Morbid Growth from the Cranial Bones” (p. 416).

Several of Dr. R. Quain’s reports have reference to cases of
fatty and fibrinous degeneration of the muscular tissue of the
heart. With the former of these modes of atrophy Dr. R.
Quain’s name will always be intimately connected; and we
need not say that what he may state on the subject is always
worthy of attention.

He also gives an account (p. 247) of a ‘‘ Case of Malignant
Tumour in the Brain,” with reference to which it is remarked
that

‘* the extremely close resemblance which this tumour bore in its general
appearance to an old apoplectic effusion was a remarkable fact well worth
attention, and the result showed how very valuable is the aid of the micro-
scope in determining the nature of these and similar lesions.”

In a case (p. 254) in which the rare combination of encepha-
loid tumour (in the anterior mediastinum) and tubercle was
met with, Dr. R. Quain gives the following Report on the

Microscopic Characters of the diseased Tissues :-—

“* Encephaloid Mass.

*< 1. On section of a pearly-white
colour ; spotted freely with vascu-
larity and with apparently effused
blood.

* 2. Of solid (elastic) consistence,
but friable, yielding, on gentle pres-
sure, a quantity of viscous pearly-
coloured fluid or juice.

** 3. With the microscope found
to consist of a great number of cells
enclosed in large meshes, formed by
the interlacement of bundles of a
filamentous tissue, sui generis. The
cells are rather larger than blood
corpuscles, are of all shapes, but
generally spherical, and contain
from one to five nucleoli. These
are rendered more distinct by acetic
acid. Few cells contain distinct
nuclei. There are also numerous
compound granule or mulberry cells,
and in many parts oily particles.
Blood-vessels and _blood-globules
abound,

** Tuberculous Deposit.

“<1. Of a pale yellow or buff colour,
not presenting any appearance of
blood or blood-vessels.

‘«« 2. In some portions solid and
tough, in others of a cheesy con-
sistence, and in others of that of
thick cream; the solid parts not
affording fluid or juice on pressure.

«¢ 3. With the microscope found
to consist of cells, granular par-
ticles, and fragments of broken-up
fibres ; also to contain some fine fi-
laments, disposed without arrange-
ment, and evidently derived from
the lung texture. The cells, which
are mostly spherical, are smaller
than those from the encephaloid
mass, and contain apparently more
numerous and much smaller gra-
nules. These, as in the latter, are
rendered more distinct by acetic
acid. Oily particles are seen, more
especially in the softened matter.
Neither blood-globules nor vessels
are seen.”

128 REPORT OF PATHOLOGICAL SOCIETY.

In a case of fatty degeneration of the heart (p. 263), and in
which rupture of that organ took place, the affection appears
to have been local or circumscribed, the muscular fibre in
other parts of the heart being ina remarkably healthy condition.
The local degeneration or atrophy was evidently connected
with a diseased condition of a branch of the coronary artery
distributed to this part of the heart. Dr. Baly reports another
case of rupture of the heart consequent upon fatty degenera-
tion, and in this case also, the alteration seemed to be more
local than general; but the condition of the coronary arteries
is not adverted to. Fatty degeneration was present in some of
the cerebral vessels in the same case. In another case of rup-
tured heart, with local fatty degeneration, recorded by Dr.
Quain, the anterior branch of the coronary artery, leading
directly to the disease, was seen to be greatly ossified, and,
about the middle of its course, completely obstructed.

Dr. Bence Jones reports a case in which Sarcina ventriculi
was found in the urine of a boy. In the present case it seems
pretty clear that this was accidental, and that the Sarcina
really came from the stomach, but at the same time we would
observe, that it does not appear to be possible to account for the
presence of Sarcina in the urine zn all cases in the same way.
In the cases recorded by Heller (Archiv. d. Chemie, u. Mikro-
skopie, Heft 4, 1847, and Heft 1, neue Folge, p. 30, 1852) _
there seems every reason for the belief that the Sareina was
produced in the urine itself. In the latter of the cases de-
scribed by Heller the Sarcina occurred not merely mixed
with other sediments, but in such quantity as to form a loose,
white deposit an inch in height, composed wholly of the
Sarcina, or with a slight admixture of carbonate of lime. It
is interesting that in all these cases of Sarcina in the urine
recorded by Dr. Heller there were symptoms indicative of
cerebral or other nervous lesion. Dr. J. H. Bennett, in his
Lectures on Clinical Medicine (p. 214, 1851), notices a case
related by Dr. Mackay.

Microscopical observations on the so-termed serous cysts in
the kidney are afforded by Drs. Brinton and Bristowe and by
Dr. Bence Jones, who examined their contents chemically.
These observations, however, leave the verata questio of the
genesis of the cysts very much as it was.

Dr. Bristowe assigns reasons (pp. 380-1) for the conclusion
that they cannot be Malpighian bodies (“at least, not healthy
ones,” he oddly adds), which do not appear to us altogether so
cogent as he would seem to think them; and that they are
not dilated tubuli he thinks is sufficiently shown by the cir-
cumstance that he has never seen a cyst continuous with a

REPORT OF PATHOLOGICAL SOCIETY. Ie

tube—a condition, we should imagine, not likely to ocenr,
seeing that the complete occlusion of thre tube on each side is
indispensable to the formation of the shut cyst. He also
dismisses the notion of their being * fresh formations arising
from cytoblasts” as untenable ; aad he is consequently oblined
to confess that he is unprepared to say how these cysts arise.

In the next case (pp. 381-2), which is reported upon by
Drs. Brinton and Bristowe, it would appear that the microscopic
cysts differed in some respects from those in the former: they
were much less uniform in size—sometimes solitary and some-
times ciustered : they could be readily isolated and moved about
the field of the microscope. They varied greatly in magnitude,
the smallest being little larger than renal epithelial cells, the
largest about fee” size of Malpighian bodies. ‘The observa-
tions of Drs. Brinton and Bristowe would seem to have been
limited in great measure, though not entirely, to the minute
microscopic cysts. Dr. Bence Jones refers more particularly
to the larger ones. In the contents of these he was unable to
discover any of the elements of urine, nor could any epithelial
lining be detected. It is left to be inferred from this, at
least we presume so, that these large cysts could not be dilated
tubuli. But again, this conclusion seems to have been drawn
hastily. The strongest point in the argument is perhaps the
absence of epithelium on the inner surface of the cyst. But
the force of this circumstance, perhaps not in itself of such
very great importance, is, at all events, much invalidated by
the certain fact that these cysts do occasionally exhibit an
epithelial lining. Perbaps they must be examined in a very
fresh state to show it; but that such a lining does sometimes
exist is within our own observation. The truth of the matter
after all may be this: that the serous cysts are of different
kinds; that some, as in Dr. Bristowe’s first case, are due to
dilated Malpighian capsules ; ; that others, as the smaller ones
in the second case, originate in dilated epithelial cells 5 and
lastly, that the larger ones are dilated tubuli, that is, in their
advanced aS They may have originally ennmeie ad
in one of the second class. This opinion, which has long
appeared to us likely to afford a more satisfactory explanation
of these cysts than one more exclusive can do, we are glad to
find coincides with that of Kolliker (Manual of Human
Histology, pp. 477-8), who also fully confirms Dr. Johnson’s
view by an observation of his own.

Our space will merely allow us to refer to Mr. Toynbee’s
valuable contribution to the knowledge of Tubercle (p. 355) ;
and to Dr. Bristowe’s account of “ A Malignant Disease of a
Cystic Ovary” (p. 404, with plate); as well as to Mr,

MOL. 1, K

130 LEUCOCYTHEMIA, OR WHITE CELL-BLOOD.

Quekett’s “ Comparative view of the Condition of the various
Muscles in three cases of Non-Congenital Club-foot’—all
more or less instances of atrophy. With reference to the
figures (pl. xii.) belonging to this paper, we should much like
to have had Mr. Quekett’s explanation of the appearance pre-
sented by fig. 2. Were not such a thing almost impossible,
one might deem that Dr. Barry’s contorted views on the struc-
ture of muscular fibre had found confirmation to some extent
in the hands of the Professor of Histology of the Royal Col-
lege of Surgeons.

LrucocyTuHEmIiA, or White-Cell Blood, in Relation to the Physiology and
Pathology of the Lymphatic Glandular System. By Jonn Hucurs
Bennett, M.D., f.R.S.E. Edinburgh: Sutherland and Knox.

No branch of science has been benefited by the employ-
ment of the microscope so much as physiology. So great, in
fact, have been the advantages accruing to the study of vege-
table and animal histology by the aid of this instrument, that
it is regarded by some scientific observers as exclusively the
property of this branch of science. Although physiology had
latterly made rapid strides by the aid of chemistry, especially
when applied in the investigation of the first and last facts of
a given series of phenomena, it still failed to supply the
means of examining those intervening links in the chain which
occurred within the organism of plants and animals. In
revealing the great fact that animal and vegetable tissues are
principally composed of cells, and that all the functions they
exhibit are the result of the properties of individual cells, the
microscope laid the foundation of a true science of life.
Since its first application in this direction, the physiology of
plants and animals has become a new science; the old sys-
tems are gradually retiring, and everywhere more accurate and
profounder views of the nature of life and organization are
supplanting doctrines which had become venerable only for
the want of the means of testing their truth. At the same
time that the microscope is furnishing the means for a more
philosophic study of the functions of plants and animals, it
promises to render their study more definitely available for
the practical ends which the medical practitioner has in view.
The success of empirical practice, and the encouragement
given to irregular systems of treating disease, have not arisen
so much from the ignorance of the public, as from the com-
paratively feeble assistance which the prevailing doctrines of
physiology and theories of disease were capable of affording

LEUCOCYTHEMIA, OR WHITE-CELL BLOOD. 131

to the most learned physician. This time is passing by, and
the microscope, in conjunction with a chemistry which, if it
cannot imitate, is at least beginning to trace accurately the
changes undergone by the elements contained in a living cell,
is hastening the time when physiology shall pass from the
speculative to the certain sciences, and medicine no longer
remain a conjectural art. Already has it pointed out the
differences between diseased and healthy tissues, and afforded
a means of diagnosis which did not previously exist. The
secretions, the contents of the viscera, and above all the blood,
can be examined with an accuracy which seems to promise a
sufficient means for working out the phenomena of health and
disease.

These general remarks have naturally occurred as intro-
ductory to the notice of a book which describes a disor-
dered condition of the blood, which could only be detected
by the microscope, and which presents us with inferences
from the conditions thus observed, having a wide range of
application, and embracing the discussion of most important
generalizations. The condition of the blood described is
called by Dr. Bennett Leucocythemia (Acvuss xutos aia), and
consists essentially in the presence of a larger number than
usual of white cells amongst the red slobiiles of the blood.
The work contains a ceded of thirty-five cases in which this
condition was observed before or after death. The mode of
ascertaining the condition of the blood whilst the patient was
living was to puncture slightly the end of the finger with a
lancet. On placing a drop of the blood thus procured under
a microscope, the coloured corpuscles were found to collect
together in rolls, whilst the colourless corpuscles filled up the
intervening space. Acetic acid was found to dissolve up the
coloured bodies, and to render the colourless ones very trans-
parent. The latter, thus treated, presented a nucleus, in some
consisting of a single round or oval body, but in the majority
presenting two, three, or even four granules, each having a
depression in its centre. Sometimes the nucleus was cres-
centic, or in the form of a horseshoe. These appearances
were presented in most of the cases examined. It is difficult
to estimate the proportions of the corpuscles, but Dr. Bennett
states that, when all the meshes or interspaces between the
coloured corpuscles are filled up with colourless ones, the
latter may be estimated at one-third.

After detailing the cases with great accuracy, the author
enters into a variety of general considerations, to some of
which we would draw attention. One of the most remarkable
facts in connection with this condition of the blood is the

kK 2

132 LEUCOCYTHEMIA, OR WHITE CELL-BLOOD.

almost constant presence of disease of the spleen and lymph-
atic glands. Of nineteen cases in which the body was
examined after death, the spleen was enlarged in sixteen, and
the lymphatic glands were more or less diseased in eleven.
The chapter on the diseased condition of bodies presenting
the white-cell blood is followed by a discussion on the
relation existing between the colourless and coloured cor-
puscles of the blood, and the origin and destination of the
blood corpuscles. We cannot follow the author through this
argument, but give his conclusions :—

“1. That the blood corpuscles of vertebrate animals are originally
formed in the lymphatic glandular system, and that the great majority of
them, on joining the circulation, become coloured in a manner that is as
yet unexplained. Hence the blood may be considered as a secretion from
the lymphatic glands, although in the higher animals that secretion only
becomes fully formed aficr it has received colour by exposure to oxygen in
the lungs.

“2, That, in mammalia, the lymphatic glandular system is composed
of the spleen, thymus, thyroid, supra-renal, pituitary, pineal, and lymph-
atic glands.

“3. That, in fishes, reptiles, and birds, the coloured blood corpuscles
are nucleated cells, originating in these glands : but that, in mammals, they
are free nuclei, sometimes derived as such from the glands ; at others, de-
veloped within colourless cells.

“4, That, in certain hypertrophies of the lymphatic glands, their cell
elements are multiplied to an unusual extent, and under such circumstances
find their way into the blood, and constitute an increase in the number of
its colourless cells. This is leucocythemia.

“5. That the solution of the blood corpuscles, conjoined with the effete
matter derived from the secondary digestion of the tissues, which is not
converted into albumen, constitutes blood fibrin.”—p. 112.

Dr. Bennett then enters upon the consideration of various
pathological conditions, on which his investigations on the
nature of white-cell blood seem to throw light. By far the
most important of these is inflammation. It is a prevalent
notion that the accumulation of the colourless corpuscles
within some of the smaller vessels is an essential condition
of this important pathological condition. The discovery of
white-cell blood, in which the colourless corpuscles of the
body abound, must be regarded as opposed to this view.
Dr. Bennett says—

“On the other hand, every known fact convinces me, and the progress
of science only adds strength to my convictions, that we must ascribe the
ultimate cause of inflammation to a derangement of those forces which re-
gulate the nutritive powers of the economy, and that the only correct defi-
nition of inflammation itself is—an exudation of the normal liquor san-
guinis, It is in vain that physiologists seek in the alterations of the ves-
sels on the one hand, or in morbid changes of the blood on the other, for
the primary cause of this important condition. Facts prove that both are
more or less affected, and also show that neither the one change nor the
other, nor the two combined, constitute inflammation. The vital properties

HANDBOOK OF HUMAN HISTOLOGY. 133

of the tissues (understanding by these the unknown conditions necessary
for carrying on the nutritive processes) are in all such cases deranged, and
such alteration is the cause of the changes which have been referred to,
and not the effect.””»—p. 115.

The work is accompanied with two coloured lithographs
and a large number of woodcuts illustrative of the condition
of the blood globules. It will be read with interest by the
medical man, and is a capital instance of the value of the
microscope in the practice of medicine, not only as affording
the facts on which alone sound physiological theories can be
based, but as the only means of discriminating between many
very different pathological conditions.

HanpsucH DER GEWEBE-LEHRE DES MENSCHEN FUR AERZTE UND STUDI-
RENDE, mnit 313 Holzschnitten. Von A. K6uLutKer, Prof. d. Anat. u.
Physiol. in Wurzburg. (Handbook of Human Histology, for Prac-
titioners and Students, with 313 Woodcuts. By Prof, A. Kolliker.)

*¢ MepicrnE has arrived at such a stage that Microscopical Anatomy ap-
pears to form its foundation, as much as the anatomy of the organs and
systems; and a thorough study of Physiology and Pathological Anatomy
is impossible without an exact knowledge of the most minute formal ele-
ments. It becomes then the duty of those who cultivate this field of
science not only to communicate their observations to their fellow-workers
and to those who are more profoundly acquainted with medicine, but to
enable all those who are concerned with the study of Man, and especially
students and practitioners, to profit thereby. The present work seeks to
perform this task by giving as condensed as possible a view of the rela-
tions of the elementary parts of the body and of the more minute structure
of the organs ; avoiding all polemical discussions, with the exception of a
few of the more important points as yet swb judice, and leaving the history
of the science completely in the background; but, on the other hand, en-
tering as fully as possible into those points which bear upon Physiology,
Pathological Anatomy, and Comparative Histclogy.”

Such is Professor Kolliker’s preface to the very admirable
work in which he exhibits the result of his manifold and
long-continued microscopical researches into the structure of
the human body. Nor has Professor Kolliker’s performance
fallen short of these his professed intentions. Any one who
will carefully study the work will, we think, agree with us,
that since the publication of Henle’s ‘ Allgemeine Anatomie,
ten years ago, no histological manual has appeared in any
country* at all comparable with it for exact research in
matters of detail, for completeness as a whole, for breadth of
view, and last, but by no means least, for the conscientious
care with which the author has in almost every case made

* Our readers will think we have forgotten the admirable work of Todd
and Bowman ; but it has never been completed.

134 HANDBOOK OF HUMAN HISTOLOGY.

himself acquainted with the literature of his subject. We
mention this good quality particularly, because we have been
surprised to meet with one or two defects, arising, as we think,
from the Professor's having overlooked good work performed
on this side of the Channel. The chapter on the Blood,
pp. 565-584, for instance, seems to us to be the weakest in
the book ; and we can hardly think it would have been so, had
Professor Ko6lliker sufficiently studied the observations, pub-
lished in this country so long ago as 1845, by Mr. Wharton
Jones,* in a memoir which we consider to be one of the most
important contributions ever made to our knowledge of this
subject.

We have unfortunately no space to enter into a detailed
criticism, but we must remark that Wharton Jones has here
demonstrated (958) that the “ stellate lymph corpuscles,”
figured by Kolliker (fig. 290), are formed by a peculiar shoot-
ing out of the wall of the lymph corpuscle, and not by any
“exit of theircontents.” (Kolliker, note, p. 565.) Professor
Kolliker is one of those who have paid most attention to the
phenomena of contraction presented by simple cell membranes,
but he has forgotten to mention one of its most extraordinary
and earliest discovered instances—that Amoeba-like motion of
the “colourless corpuscle,’”’ described by Wharton Jones, in
the blood of the skate, frog, &c. (loc. cit., § 9-24), and
quite readily visible by any one who looks carefully after it
even in the human “ colourless corpuscle.”

There is yet a process which Professor Kolliker takes pretty
much for granted—we refer to a supposed natural division of
the nucleus of the colourless corpuscle, and to the consequent
occurrence of multiple and biscuit-shaped nuclei; but any
belief in which, must, we think, be greatly shaken by the
perusal of §§ 29-30, 63-66, of Wharton Jones’s Memoir,
and by the repetition of his experiments (we have often
repeated them in man) be completely destroyed. Certain it
is, that the more gradually and carefully the re-agent is
applied, the more certain is one to find the colourless cor-
puscles of the blood with only circular nuclei, while, if it be
applied suddenly and concentrated, one is almost equally
certain to find them with nuclei of every irregularity of
shape, from biscuit-shaped to mulberry-shaped.

Finally, considering that “the origin of the blood corpuscles
after birth and in the adult”’ is “one of the most obscure
portions of the history of the blood-cell” (Kolliker, p. 581),we

* Philosophical 'Transactions, 1846, Part II., ‘‘ The Blood Corpuscle
consideved in its different Phases of Development in the Animal Series.”

STRUCTURE OF MUSCULAR FIBRE. 135

think that the very strong arguments, not to say the complete
demonstration, contained in the memoir so often referred to,
that the blood corpuscle is the free nucleus of the * colour-
less corpuscle,” deserved grave consideration, and, at any rate,
should not have been passed over in silence. Professor Kolli-
ker’s own view, that the red corpuscles are the small lymph
corpuscles (Chylus Kérperchen), which have lost their nucleus
and become coloured, is, we think, totally untenable.

We regret to have had to find any fault with a work which
is, in so many respects, faultless. It is only our sense of the
great influence it is likely to have which has compelled us
to do such violence to our feelings of gratitude towards its
author.

Mémoires de la Société de Physique et d Histoire Naturelle de
Genéve. Tome xii. ler Partie, pp. 169. 1849.

1. Microscopic OBSERVATIONS ON THE STRUCTURE OF MuscuLAR FipRe.
By Dr. J. L. Prevost,

NotwitustanDinG the profession with which the author com-
mences, of his intention to give a more precise description of
muscular fibre than had previously appeared, we are un-
able to perceive that this laudable object has been in the
slightest degree carried out. There is little or nothing in the
paper worthy of notice, and the illustrations are equally use-
less. It is only surprising that so lately as 1849 such a de-
scription of the mode of origin of muscular fibre could have
appeared as this :—

** Fibrine is the principal constituent of muscles. Soluble in the blood,
it circulates with it, and is eventually deposited on the cellular frame-
work, which determines the form and direction of the muscular fibres.
This is seen very well in the embryo of the vertebrata. At first the vo-
luntary muscles present rows of cellular cylinders, along which run nu-
merous blood-vessels ; shortly afterwards these cylinders are filled with
organized fibrine.”

He describes some experiments upon portions of muscle
taken from the leg of Carabus auratus, in which the muscle
was exposed to the action of solutions of strychnine, hydrocy-
anic acid, sulphate of morphia, and chlorine. According to
him the isolated muscles of this insect will continue to ex-
hibit contractile movements for twenty minutes or more when
immersed in water. Strychnine, after producing violent con-
tractions and elongations, (!) destroys this irritability in about
ten minutes. Prussic acid acts, according to M. Prevost,
more quickly, but the contractility even under its influence

136 BRITISH ZOOPHYTES.—MARINE POLYZOA.

lasts for a minute or more, and morphia does not put it to
sleep under eight minutes; whilst a solution of chlorine in
water, strange to say, acts as an invigorating agent, for under
its agency the movements are said to have persisted for half
an hour or more.

It is needless to remark upon such experimental results as
these.

2. Nore RELATIVE AUX APPARENCES MIcroscopIQUES DES CHEVEUX
HouMAINS ET DES Ports pD’ANIMAUX. By M. A. Morin.

A murder having been committed some months previously
on the person of a forest-guard, in the Pays de Gex, M.
Morin and another were charged with the duty of determin-
ing whether a hair, three lines long, found on the handle of an
axe, taken in the house of a suspected person, were that of a
man or of some animal.

The author adverts to a previous case of an analogous kind,
which occurred in 1837, and, according to him, is the only
one ; it is reported by M. Olivier d’ Angers.

M. Olivier appears to have distinguished human hair from
that of the horse and ox, simply by the existence in the former
of a central canal. Notwithstanding this absurd notion,
which could only have arisen in an optical delusion, his deci-
sion happened by chance to be correct.

M. Morin, who appears to be equally ignorant of any suffi-
cient distinction between the hairs of man and certain do-
mestic animals, also arrived at what was probably a correct
result. The only distinctive character upon which he seems
to lay any stress consists in this,—that, according to him, the
human hair possesses a general transparency, which is wanting
in the others! Neither of these cases, though the decision of
the question in both was probably right, should be cited as
an instance of the useful application of the microscope to
medico-judicial inquiries. M. Morin gives several figures of
different hairs, but they are coarse and useless.

A PoruLtar Hisrory or Brrrish Zoorpytes. By the Rev. D. Lanps-
sornouGH, D.D. London: Reeve and Co.

A CaTALOGuE of Martine Potyzoa in the Collection of the British Mu-
seum. Part I. By Grorce Busk, F.R.S. Printed by Order of the
Trustees. 1852.

THESE two works, though not of large size, are yet of interest to
a large class of microscopic observers, and especially to those
who devote attention to the attractive subject of marine zoophy-

ATLAS OF PHYSIOLOGICAL CHEMISTRY. 137

tology. ‘The first of them, which forms one of Mr. Reeve’s
well-known series of popular works on Natural History, is from
the welcome pen of Dr. Landsborough. The arrangement
followed by the author is that of Dr. Johnston, to whose
classical and most valuable work on the same subject * he
confesses himself to be mainly indebted for the substance of
his own compendium. Several new species, however, are
described, and the figures are for the most part original and
from nature. These figures exhibit numerous species, both in
the natural size and magnified ; they have been remarkably well
etched on stone by Mr. Achilles. ‘The second work, of which
we here have only the first part, contains sixty-eight plates—
containing magnified figures, drawn toa scale, of about 123
species, constituting a portion only of the Celleporina of Dr.
Johnston, or of what the author (Mr. Busk) terms the “ Cheilo-
stomata.” It also contains an arrangement of the species of
this numerous and much-neglected class, differing in some
respects from any former one ; and short, descriptive, and dis-
tinctive characters of the various Orders, Sub-orders, Families,
Genera, and Species, and the habitats of each species. The
work, when complete, will afford, to a certain extent, a means
for a more accurate comparison between the different species,
and a more satisfactory view of their distribution on the sur-
face of the earth, than has hitherto been possible. We defer
a more detailed notice of this catalogue until such completion
has been effected, here merely observing that the present part
contains the Families Catenicellidae — Salicornariadzee—Cel-
lulariade — Scrupariade—Farciminariade—Gemellariada—
Cabereadze — Bicellariadae—and Flustrade.

ATLAS DER PHYSIOLOGISCHEN CHEMIE. (Atlas of Physiological Chemistry.)
By Dr. Orro Funke. Leipsic: Engelmann. London: Williams
and Norgate.

Tuis work consists of fifteen plates, with six microscopical
subjects on each plate, and is intended as a supplement to Dr,
Lehmann’s admirable Manual of Physiological Chemistry.
‘The English reader already possesses a translation of this work
by Dr. Day, published by the Cavendish Society. The pub-
lication of this Atlas will not only be acceptable to those who
possess that work, but to all who are interested in microsco-
pical chemistry. A reference to Dr. Lehmann’s work will
clearly show that there are many products of great interest in

* A History of the British Zoophytes. By George Johnston, M.D.,
LL.D. 2nd edit. 1847. Van Voorst.

138 CURIOSITIES OF THE MICROSCOPE.

the blood and secretions of the human body which, although they
have a complicated chemical structure, are yet easily recognised
by means of the microscope. A knowledge of the forms which
these substances assume will be easily acquired by means of
the present Atlas. These illustrations, however, are not con-
fined to chemical compounds, but wherever particular condi-
tions of the solids or fluids of the body have been referred to
by Dr. Lehmann, needing the microscope for their elucidation,
they have been given by Dr. Funke. The plates are litho-
graphed, and, wherever colour is required, it has been done
from the stone, and we may point to them as good examples
of what may be accomplished for the illustration of micro-
scopic objects by these processes.

CURIOSITIES OF THE MicroscopE. By the Rev. Jos. H. Wyrues, M.D.
Philadelphia: Lindsay and Blakiston.

In our last number we noticed a work by Dr. Wythes, in
which we pointed out a number of plagiarisms, without the
slightest acknowledgment. We are sorry to have to announce
that the present work is, if possible, a still worse instance of
the appropriation of the literary property of others. The
design of this work, like that of the last, is good, but, as in
that work, it is badly carried out, and scarcely a sentence can
claim to be regarded as original. The work consists of de-
scriptions of microscopic objects, with plates, for the use of
young people. The principal subject treated of is the family
of Infusoria, and the plates and descriptions are directly copied
from a work by Miss Agnes Catlow, published by Messrs.
Reeve and Benham, with the title of ‘ Drops of Water.’ On
account of the proved plagiarism of this part of the work, we
understand the publishers of Miss Catlow’s book have been
enabled to prevent the further sale of the American work.
We have felt it our duty to call attention to this gross violation
of the rights of authorship, and regret to find that it has been
perpetrated by a gentleman who claims by his titles to belong
to both the medical and clerical professions.

MEMORANDA. 139

NOTES AND CORRESPONDENCE.

On Microscopical Re-agents.— [he list of re-agents, and
the instructions for using them, given in your last number,
cannot but be useful to all who are commencing the study of
the Microscope. There is, however, one point connected with
these re-agents of such vast importance that | cannot forbear
urging it on your notice, in the hope that you may devote
some portion of your space to its discussion and elucidation:
I refer to the various and unusual crystalline forms which
many re-agents assume when they meet under the microscope.
Without a knowledge of these singular facts, and without a
perfect recognition of the crystalline forms, errors in micro-
chemical investigations cannot but occur. I will illustrate my
meaning by a few examples, which must be familiar to many
observers, but which I do not happen to have seen noticed.

1. Liquor potassee is a common re-agent in microscopy.
Itself a liquid, and its principal combination with carbonic
acid being a highly deliquescent salt, no agent could be
thought more free from possible fallacy. If, however, a drop
of potash be allowed to evaporate on a slip of glass, crystals
appear, some of which are of a very remarkable form. They
are chiefly six-sided tables, exactly like cystine. When in
quantity they are often crowded together, as the cystine
plates are, and sometimes exhibit a similar nucleus-like body
in their centres. If a larger portion of liquor potasse be put
in a watch-glass, in a few weeks’ time a mass of dry crystals
appear, which are chiefly composed of innumerable needles
aggregated together.

I at first thought that these crystals were the result of im-
purities, but on procuring some perfectly pure potash, the
same as that which was used by Mr. Graham in his diffusion-
experiments, the same phenomena were observed.

The crystals thus formed appear to be a carbonate of
potash, but I have been unable to form them from the usual
carbonates. I have tested these crystals carefully for nitric
acid, without detecting any, and for sulphuric acid, a trace
of which can sometimes, but not always, be found. They
effervesce with acids, and of course dissolve in water, but
not with extreme readiness, that is to say, not like a deli-
quescent salt.

140 MEMORANDA.

I need hardly remark, how thoroughly any one working
with liquor potasse might be deceived if he were not aware
of these facts.

2. Every one knows that acetate of potash is a very deli-
quescent salt, and that, when it is formed under the micro-
scope, it generally soon disappears. But acetate of potash,
forming by the union of its constituents, and crystallizing out
of acetic acid, is (as long as acid is present) a stable salt,
which has a crystalline form, widely differing from acetate of
potash crystallizing out of water. And (a most remarkable
circumstance) the form of the acetate of potash varies accord-
ing to the strength of the acid out of which it crystallizes, so
that there is a great range of phenomena, which might tend
to mislead even a very careful observer. As the crystals
forming in liquor potassze often resemble cystine, so the
acetate of potash, forming out of strong acid, resembles, to a
certain extent, some form of uric acid. For, mixed up with
other forms, long dagger-like or lancet-shaped crystals are
seen, which, if we were on the gui vive for uric acid, might
very well deceive us. I need not say how frequently in
micro-chemical research these two common re-agents may
meet on one slip of glass.

3. The re-action of iodine again is a most important one.
The rule is, that iodine colours starch blue; but in certain
albuminous mixtures, as pointed out lately by Mayjendie at
the College of France, iodine loses this property, and, as far
as starch is concerned, is temporarily indetectible. This
difficulty must be done away with before iodine can be used
without fear in micro-chemistry.

4, One more singular instance of modification of pro-
perties from admixture may be mentioned. Acetate of pot-
ash and chloride of calcium are separately highly deliques-
cent salts. Mix together acetic acid, liquor potasse, and
chloride of calcium, so as to have some slight excess of acetic
acid, the mixture will evaporate to a solid, dry, crystalline mass.
Now, in complex fiuids, such as blood, exudations, and even
in urine, these four re-agents may very easily occur together
under the microscope, and the resulting crystals may mislead.
I do not know that a mistake from this cause has ever actu-
ally arisen, but its possibility is evident.

I might narrate various other curious re-actions, had I time
or did your space permit. Enough has been said to show
that in micro-chemistry we require a thorough examination of
the behaviour of our re-agents among themselves, before we
bring them into play on other bodies. Such an examination
I should hope some of your young energetic readers will take

MEMORANDA. 141

up, and it is for the purpose of inciting some one to do so
that I have written this letter. It is evident also that not
only micro-chemistry will benefit by this inquiry, but that
crystallography may thus be studied under (as far as I know)
a different aspect, and that not only the microscopist, but
even the chemist may acquire, from the phenomena of crys-
tallization under unusual circumstances, some increase of the
present knowledge of physical and chemical re-actions.—

E, A. Parkes, M.D., Harley Street, Cavendish Square.

On Thin Glass-Covers.—Most persons who have treated
themselves to the luxury of a microscopic object-glass of large
aperture and high power, have experienced the disappoint-
ment of finding that some pet object, whose structure they
expected to see finely developed, has been permanently
mounted under a cover so thick as to put vision with such a
glass entirely out of the question.

The reason of this is, not that very thin glass cannot be
procured, or that it is particularly expensive (for the increased
quantity of the thinner material contained in the same weight
fully compensates for the increased price), but that the deli-
cate manipulation required in cutting and cleaning it induces
those who mount objects for sale, as well as most others, to
prefer a glass of greater thickness.

It is desirable that no object which may require to be sub-
mitted to a higher power than a quarter-inch object-glass of
75° aperture should ever be mounted under a cover thicker
than 1-140th (,007) of an inch. Indeed, if the aperture of
the object-glass exceeds 120°, the best thickness for the cover
is 1-250th (,004) of an inch. Glass of this thickness can
easily be cut with a good writing diamond when laid on a
piece of plate-glass, as proposed by Mr. Warington, and de-
scribed in Mr. Quekett’s Treatise on the Microscope, second
edition, p. 265; but in the cleaning, a great many pieces are
usually broken. The following method, which is often used
by chemists for cleansing test-tubes, &c., | have found to suc-
ceed :—Place the covers in a small cup or glass, and pour
over them enough strong sulphuric acid (common oil of vitriol)
to wet every part of them. Let them stand for a day or two;
then wash them in repeated waters until all the acid is re-
moved. Stretch a clean cambric handkerchief tight over any
flat surface, such as a piece of plate-glass or a druggist’s pill-
slab, and lay the glasses on it a few at a time. By rubbing
them very gently with another handkerchief on the finger,
they may be dried without using sufficient force to break
them. They should then be removed to a clean box with

142 MEMORANDA.

forceps, and carefully kept from dust,and from contact with
the fingers. Before, however, they have undergone this
careful cleansing, the covers should be sorted according to
their thickness, the readiest method of doing which is by
means of an instrument made by Mr. Ross, called a “ lever of
contact.” It consists of a long, slender index, having a pro-
jecting touch near the centre of motion, which is kept in con-
tact with a plane surface by means of a spring. When a piece
of glass is inserted under the touch, the index points to the
thickness on a graduated arc. In this way covers may be
sorted very rapidly.

The same thing may be accomplished less readily by
merely placing a fragment in the pliers, with the edge up-
wards, under the microscope, armed with an inch object-glass
and an eye-piece micrometer, and measuring its thickness in
the usual way.

When an object is already mounted, neither of these
methods is applicable; but the thickness of the covering-
glass may then be ascertained very nearly by having the head
of the fine adjusting screw graduated, and ascertaining the
value of the graduations on a piece of glass previously mea-
sured by either of the former methods. For example, the
screw-head in my microscope is divided into ten; and to
focus from the lower to the upper surface of a piece of glass
1-100th of an inch thick, takes one tum and six-tenths, or
16 divisions ; consequently, it would take 1600 divisions to
focus through an inch of similar glass. Therefore, if I divide
1600 by the number of divisions through which the screw has
been moved, I shall obtain the thickness in the vulgar frac-
tion of an inch, or the decimal expression of the same quan-
tity by dividing the number of divisions by 1600. Unless
the glass has been carefully wiped, some specks will be
readily found by which to adjust the focus——GrorcE JACKSON,
Church Street, Spitalfields.

Achromatic Gas-Lamp for the Microscope. —Gas asa
source of light presents great advantages over oil and spirit, on
account of cleanliness, being ever ready for use, and affording a
perfect control over the flame; but when the ordinary gas-
lamps are used for the purpose of illuminating the field of
the microscope a yellow glaring light is given, alike injurious
to the eye and the definition of the object under examina-
tion. To correct these evils, I have arranged a lamp which
is also otherwise useful to the microscopist. It consists of
a stage, A, supported by a tube and socket, sliding on an
upright rod rising from the stand, This carries an Argand

MEMORANDA. 143

burner, B ; a metal cone, C, rises to the level of the burner,
and is about one-eighth of an inch from its outer margin.

This arrangement gives a bright cylindrical flame. The
bottom of the stage, B, is covered with wire gauze, to cut off
irregular currents of air, and thus secures a steady flame. Over
the burner is placed a Leblond’s blue glass chimney, D,
This corrects the colour of the flame to a certain extent; but
it is still further rectified by a disc of bluish black neutral
tint glass, E, fitted in a tube, F, attached obliquely to the
shield, G. G is a half cylinder of metal, which serves to
shield the eyes from all extraneous light, but may be rotated
on the stage, A, by aid of the ivory knob, H, when the full
light from the flame is desired. A metallic reflector, I, fixed
on its support, so as to be parallel to E, concentrates the
light. By the combination of the two glasses, D and E, the
yellow rays of the flame are absorbed, and the arrangement
affords a soft white light which may be still further improved
by receiving the rays on a concave mirror, backed with
plaster of Paris, L; and where a very strong light is re-
quired, a condensing lens should be interposed between the
lamp and the mirror of the microscope. By removing the

144 MEMORANDA.

shield, G, and bringing the shade, M, over the burner, it
may be used as a reading-lamp. A retort ring, aN, , supports
a water-bath, O, or a wrought-iron plate, P, 6 inches by 24
inches, both used in mounting objects. The stop-cock, Q,

ives the means of regulating the flame. The screw, R,
clamps the lamp-head at any height desired. The lamp may
be attached to any gas supply, by vulcanized India-rubber
tubing.

This lamp might be used for many other purposes, as for
minute dissections, watchmaking, engraving, &c. A Le-
blond’s chimney, in combination with an outer glass globe of
a bluish black neutral tint, might be with advantage used
in our dwellings.—SamueEt Hientey, Jun., 32, Fleet Street.

Gold-Bust under the Microscope.— Mr. Warren De la Rue
has sent us some specimens of African gold dust, mounted
for microscopic examination by Mr, James Nasmyth, of Patri-
croft, Manchester. Under an inch object-glass they present
an interesting object. Each grain has the irregular, smooth,
worn surface that is so characteristic of the larger nuggets,
and whilst looking at them, as Mr, Nasmyth observes, one is
almost tempted “to put out the hand and grab one or two
from so rich a field.” The examination proves that the same
causes have been at work in producing the smaller grain
which have acted upon the large nuggets.

Enfusoria in morbid discharges.— At one of the weekly
meetings of the London Medical Society, Mr. Weedon Cooke
exhibited some purulent discharge from a cancerous tongue,
which presented a large number of Infusoria. They were
of two kinds, apparently belonging to the families of Monadine
and Vibriones. Mr. Cooke stated he had not seen animal-
cules in cancerous discharges from other parts. Infusoria are
not uncommon in diseased secretions from the mouth and in
the decomposing food that collects about the teeth, and it is
probable these animalcules were not specially connected with
the diseased product in which they were found.

Red Animatcules in fooa.—M. Montagne, in a letter to
M. Flourens, which was read before the Academy of Sciences
in Paris, gives an account'of the occurrence of the Monas
prodigiosa of Ehrenberg, in various kinds of food, in a district
near Rouen in France, in July last. Pastry, fruit, vegetables,
and other articles of food suddenly exhibited an intense car-
mine or bright rose colour, which was found to depend on a
gelatinous substance, which, when examined under the mi-
croscope, presented the appearances of the animalcule de-

MEMORANDA. . 145

scribed by Ehrenberg. M. Montagne says he has succeeded
in propagating this animalcule by means of boiled rice.

@n the Occurrence of Nucleolated red Corpuscles in
Human Blood,—In the examination of some human blood,
made for the purpose more especially of observing the
changes in form occasionally assumed by the Protean colour-
less or lymph corpuscles, I was fortunate enough to meet
with a very distinct and clearly defined nucleolated red cor-
puscle, to employ the term used by Mr. Wharton Jones in
his very valuable Memoir on the Blood in the ‘ Philosophical
Transactions’ (1845). This form of corpuscle, though stated
by Mr. W. Jones to be common in the blood of the horse and
elephant, appears to have occurred to his observation but
once, and then doubtfully, in that of man. The observation
now recorded, therefore, of what must be regarded as a rare
phenomenon, and which was confirmed at the time by my
friend Mr. Huxley, may be considered of some interest and
of importance, towards the confirmation of Mr. W. Jones’s
views respecting the nature of the blood corpuscle. The
nuclear portion of the corpuscle in question was rather
smaller than most of the free blood discs, but not so small as
some of them, nor apparently much, if at all, below the mean
size of those bodies. It is to be regretted, that on my pro-
ceeding to take its dimensions with greater accuracy than by
mere comparison with the surrounding blood discs, the object
was lost. No others of a similar kind could be detected on
prolonged examination of the same blood, which, it may be
observed, was taken about an hour after his breakfast from a
young and vigorous man. The observation was made on the
4th December.—GerorcE Busk.

The Polygastrica larval states of Worms.—In the May
number of ‘Silliman’s Journal’ there isa letter from Professor
Agassiz to Mr. Dana, in which he makes the following re-
marks :—“ You may remember a paper I read at the meeting
at Cambridge (America), in August, 1849, in which I showed
that the embryo which is hatched from the egg of a Planaria
is a genuine polygastric animalcule of the genus Paramecium
as now characterised by Ehrenberg. In Steenstrup’s work
on alternate generation* you find that in the extraordinary
succession of alternate generations ending with the production
of Cercaria and its metamorphosis into Distoma a link
was wanting—the knowledge of the young hatched from the
egg of Distoma. The deficiency I can now fill. It is another
Infusorium—a genuine Opalina. With such facts before us

* Translated by the Ray Society.
VOL. I. L

146 . MEMORANDA.

there is no longer any doubt left respecting the character of
all these Polygastrica: they are the earliest larval condition of
worms. And since I have ascertained that the Vorticellz are
true Bryozoa, and botanists claim the Anentera as Alge,
there is not asingle type of these microscopic beings left which
hereafter can be considered as a class by itself in the animal
kingdom.”

Ear-Wax.—Most persons are familiar with the fact that
the wax occasionally accumulates in the external auditory pas-
sage to such an extent as to produce partial deafness. I was
under the impression that the pellet usually found was actu-
ally ceruminous, until very recently, when an opportunity was
afforded me of examining a smal] accumulation microscopically.
I found it to be composed entirely of a mucedinous fungus and
a minute portion of epithelium. On maceration in ether and
subsequent evaporation, I could find no evidence whatever of
the existence of wax. I shall be glad to know whether other
observers have noticed the same fact. If so, it is interesting as
explaining the comparative rarity of the accumulation, and in
general its small liability to return—T. Inman, M.D., Liver-
pool.

Microscopical Inquiries.— Will you kindly inform me in
your forthcoming number what kind of camera is best for
drawing from the microscope; and whether any particular
description of photographic paper is better suited than an-
other for the same purpose ?

I think that photographic pictures of microscopic objects
would be exceedingly valuable, as we should not then be
liable to error in our representations of what we see, in conse-
quence of any preconceived notions of the subject, which I
think is at present the case to some extent.—J. I.

[We shall be glad to insert queries such as the above, and
to receive answers from our correspondents. We are not clear
whether our correspondent inquires about a camera for ordi-
nary drawing or for photography.—Ebs. |

( 147 )

PROCEEDINGS OF SOCIETIES.

MiIcroscoPicaL Society oF Lonpon. 1852.

October 27.—George Busk, Esq., in the Chair. A paper by
Joseph Delves, Esq., ‘‘ On the Application of Photography to the
Representation of Microscopic Objects,” was read. After some pre-
liminary observations the author proceeded to describe his method
by stating, that the only arrangement necessary for the purposes of
Photography 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 eyepiece and of the compound body, and at
the other a groove for carrying the ground glass plate. This dark
chamber should not exceed 18 inches in length, as if longer the light
transmitted by the object glass is diffused over too large a surface,
and the picture is faint and unsatisfactory. Another advantage is,
that pictures taken at this distance are in size very nearly equal to
the object as seen in the microscope. The time of producing the
pictures varies from five to fifteen seconds.

He also made some remarks upon the mode of manipulating, and
concluded by calling attention to some very beautiful specimens,
which were exhibited, and afterwards presented to the Society.

November 24.—George Jackson, Esq., in the Chair. Messrs.
Redwood, Brown, Osborne, Ludlow, and Tischmacher were elected
members. A Paper was read by R. Hodgson, Esq., ‘‘On the Re-
production and Delineation of Microscopic Forms.” The object of
the Paper was to point out the value of the camera lucida for deli-
neating microscopic forms as compared with the various photographic
processes. In the discussion which followed the reading of this
Paper, Mr. De la Rue, Mr. Bowerbank, and Mr. Hogg expressed
their conviction, that by photography more accurate and more avail-
able pictures of microscopic objects would one day be made than
could be done by the hand. Mr. Shadbolt exhibited a very accurate
photograph, which he had succeeded in obtaining by means of a
camphine lamp. From this he thought that persons who had not
time to work at photography by day and natural light, would be
able to accomplish this object at night by artificial light.

December 29.—George Jackson, Esq., in the chair. A paper
was read by Mr. Busk on the Starch Granule, in which he showed,
in accordance with the views of Leeuwenhoek and Martens, that its
structure was vesicular. The granules were examined under the
action of heat, sulphuric acid, and other reagents, Mr. Brook ex-
hibited a moveable arm for changing object-glasses without a screw,
and a portable stand for examining objects with a pocket-glass,

L

148 PROCEEDINGS OF SOCIETIES.—OBITUARY,

PATHOLOGICAL SOCIETY.

At the meeting in November, Dr. Richard Quain brought forward
two cases of Leucocythemia. The first was the case of a man thirty-
seven years old, who had enlargement of the spleen and liver,
also of the glands of the neck and axilla, and other parts of the body.
The white cells in the blood were very numerous, and contained
nuclei. The second case was that of a woman, forty-five years of
age, who also had enlargement of the liver and spleen.

OBITUARY.

In Dr. ALGERNON MANTELL, who died on the 10th of November,
the science of microscopy has lost a most ardent cultivator. He
early perceived the value of the microscope as an instrument of
geological research, and many of his papers indicate how success-
fully he used this instrument. One of his works, entitled ‘ Thoughts
on Animalcules,’ was devoted to a subject entirely microscopical,
and displays an intimate knowledge of the structure and habits of
many of the recent species of Infusoria. As a scientific teacher
and cultivator of geology and its kindred sciences, Dr. Mantell’s
loss will be severely felt.

( 149 )

DESCRIPTION OF PLATE II.

On the Embryogeny of Orchis mascula, by Dr. Cobbold.

The letters indicate the same in all the figures :—b, bract ; p, peduncle ;
ov, ovula; n, nucleus; se, secundine; pr, primine; pé, pollen tube;
es, embryo-sac ; ev, embryonic vesicles.

Fig.

1. Flower of Orchis mascula prior to impregnation.

2.

3.{ Stages of growth of ovula before the period of fertilization (mag. 200

4, diamet.).

5.
6. Condition of the ovarium and peduncle at the time of impregnation.
7. Portion of the same (mag. 24 diamet.).

8. Fully developed ovule (mag. 200 diamet.).

= Mode of union between the pollen tube and embryo sac (figs. 9 and 10
11. mag. 250 diamet.).

On Melicerta ringens, by P. H. Gosse, Esq.

Figs. 12 to 27.—Details of the Anatomy and Development of Melicerta
ringens.
12. The animal extracted from its tube viewed sidewise.
13. The animal within its tube, expanded (the lower half omitted).
14. The same viewed in front ; ventral aspect.
15. The same; dorsal aspect.
16. The gizzard, in situ.
17. One jaw.
18. The gizzard under pressure.
19. The jaws under pressure.
=e jaw, as im situ and under pressure; the parts lettered alike, for
.) comparison.
22. A peculiar gland in the foot.
23. A ridged egg.
24, A smooth egg.
25. The young newly hatched ; ventral aspect.
26. The same, dorsal aspect.
27. The same, commencing its tube; vertical aspect.

On Melicerta ringens, by Professor Williamson.

28. Mouth of Melicerta, showing the continuity of the lower ciliated ridge,
with the arches at the side of the mouth.

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DESCRIPTION OF PLATE IV.

On a Cyst upon the Olfactory Nerve of a Horse, by J. B. Simonds, Esq.
Fig.
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 with 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,

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DESCRIPTION OF PLATE V.

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

. 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,

.* Portion of the edge of an embryo Volvox viewed in the equatorial
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 Volvowx (var. vulgaris) viewed in the
equatorial plane and representing three zoospores in situ. The
faint lines between indicate the limits of the gelatinous envelope
of each zoospore, the junctions of which are indicated by the
hexagonalareas 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; b, when
matured.

. Contents of mature winter spore, affected by solution of iodihe.
a, amylaceous granules ; 0, yellow oil.

. More highly magnified view of a winter spore compressed, to show
the double tunic.

1. The same crushed, and treated with iodine and sulphuric acid.
2. 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 Spherosira Volvow.

v

14. Zoospores in different stages of development. a, one fully divided,
seen on the side; b, the same viewed from above ; ¢, one in which
segmentation has proceeded only to the second division.

15.

16.

17. > Series of changes occurring in the hydropical condition of zoospores.

18.

Lg,

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

21
99
2

“
99
23.

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

‘| A series of changes undergone by the same zoospores in the course of
‘| twenty-four hours.

Fig. 22 shows the partial dropsy of the cell, but which did not
proceed further.
. Professor Williamson’s hexagonal areolation.

5. Ditto under iodine.
26, 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.

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

5. Section of Volvox, with its ciliated parietal cells. , vesicles in
which the ciliated gemmz are developed. Two of the gemma
seen out of focus.

6. Young gemma ruptured by pressure. 06, detached protoplasms ;
J, vesicles within which the gemma is developed; ¢, protoplasmic
membranes of three segments of the gemma. 5b, granular and
mucilaginous matter escaping from the ruptured segments.

7. Portion of a Volvox mounted in glycerine and viewed obliquely.
a, cell-walls ; b, 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 Volvox, d, superficial pellicle.

_ 18. Probable section of fig. 11.

9; 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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(149°)

ORIGINAL COMMUNICATIONS.

On the Development of the Teeth, and on the Nature and
Import of Nasmyth’s “ Persistent Capsule.” By Tuomas
H. Huxtey, F.R.S.

1 am desirous of setting forth in the course of the following
pages, as concisely as may be, the principal results to which
I have been lately led in the course of working over the
development of the human and of some other teeth. I have
directed my investigations, not to the general phenomena of
dentition, our knowledge of the course of which, firmly
established many years ago by Professor Goodsir, has not
been affected, so far as | am aware, by any subsequent in-
vestigations, but to those points of structure and develop-
ment upon which every writer, from the time of John Hunter
to the present, seems to have formed, with more or less
plausibility, an opinion of his own, different from that of all
others.

I must suppose such a knowledge of the general course of
development of the teeth as may be found in the ordinary
hand-books of physiology—my limits allowing no unnecessary
disquisition—and proceed at once to the questions whose
discussion I am about to attempt. These are, firstly: What
are the three structures which are concerned in the develop-
ment of the teeth, viz., the pulp, the capsule, and the enamel
organ, morphologically, or in relation to the parts of the
mucous membrane from which they are developed ?

Secondly : What is the relation of the dentine, the enamel,
and the cement, to these organs ?

Thirdly : What is the relation of the histological elements
which enter into the composition of the soft parts, to the
dentine, enamel, and cement, which are formed from, or
within them. :

These questions, I think, involve all the essential points
connected with the teeth. Having endeavoured to answer
them, I shall inquire with what other organs of the animal
the teeth correspond.

1. The nature of the pulp, the capsule, and the enamel organ,
with relation to the mucous membrane from which they are de-
veloped.

The teeth are developed in two ways, which are, however,

VOL. 1. M

150 HUXLEY ON THE DEVELOPMENT OF THE TEETH.

mere varieties of the same mode in the animal kingdom.* In
the first, which may be typified by the Mackerel and the
Frog, the pulp is never free, but from the first is included
within the capsule, seeming to sink down as fast as it grows.

In the other the pulp projects freely at one period above
the surface of the mucous membrane, becoming subsequently
included within a capsule formed by the involution of the
latter: a marked instance of this mode of development occurs
in the human subject. The Skate offers a sort of interme-
diate stage.

If the thick and opaque, coloured, mucous membrane of
the jaw of the Mackerel be torn away, and the alveolar edge
of the jaw be then examined with a low power, minute germs
will be seen to be imbedded in the substance of the jaw,
among the large, fully-formed teeth. One of the smallest of
those which I examined is figured at Pl. III., fig. 10. It was
an oval mass, about 1-60th of an inch in long diameter; its”
upper part was roofed as it were by the epithelium of the
gum ; its sides were constituted by a continuation of the base-
ment membrane of the mucous mémbrane of the mouth;
within this was a homogeneous substance, containing nu-
merous oval or rounded nuclei, about 1-5000th of an inch in
diameter, and continuous with the lowest layer of the epithe-
lium of the mouth. In the centre appeared a large conical
mass, nearly as long as the sac, the proper tooth pulp.
Pointed above, it widened below, and then gradually con-
tracted again, so as to form an almost hemispherical lower
extremity, which was united to the base of the sac by a
narrow neck. In the upper part of the papilla the proper
dental tissues had already begun to make their appearance ;
but below, a delicate membrane formed its outer boundary, and
this passed directly into the basement membrane of the sac.

It is clear then, that in this case the papilla is wholly a
process of the derm (or that which in a mucous membrane
corresponds to it) outwards, while the sac is a process in-
wards of the same structure; and that the homogeneous sub-
stance, with its imbedded nuclei between the two, corresponds
with the epidermis or epithelium.

In the Frog the same relations essentially hold good ; the
young teeth are here developed in minute sacs, which lie at
the bottom of the dental groove in the upper jaw. I could
never detect any free-projecting pulps (nothing, therefore,

* For the purposes of the present examination I have taken the Skate,

the Mackerel, the Frog, the Calf, and Man, as accessible specimens of each
of the great divisions of animals possessing teeth.

HUXLEY ON THE DEVELOPMENT OF THE.TEETH. 151

corresponding to the papillary stage in the human tooth), but
the smallest and youngest rudiments of the teeth 1 found were
oval or rounded sacs, 1-180th of an inch Jong, containing an
oval papilla, about one-fourth shorter. Externally, these were
bounded by a strong structureless basement membrane, which
enclosed a homogeneous substance, containing nuclei in its
cavities, "These were rounded, and very close together, next to
the basement membrane, but became transversely elongated in
the inner layers and next to the pulp. This last was bounded
by a structureless membrane, which at its narrow base became
continuous with the basement membrane of the capsule.

In the Frog, then, the relations of the pulp and of the cap-
sule are the same as in the Mackerel.

In the Skate, as is well known,* the young teeth are
developed in longitudinal rows within a deep fold of the
mucous membrane of the mouth, behind the jaw. So far as
my examinations go, however, I find: that this is not a
mere simple fold, such as it has been described to be ; but its
two walls behave just in the same manner as those of the
primitive dental groove in man—that is, they become closely
united in lines perpendicular to the direction of the jaw, so
that partitions are formed between every two rows of teeth—
transverse partitions again stretch between the separate teeth
of each row, but these did not appear to me to be complete,
terminating by an arcuated border below (fig. 11). Each longi-
tudinal canal therefore answers to a single elongated mammalian
follicle, or to that prolongation of the alveolar groove from
which the posterior permanent molars are formed in man (see
Goodsir), only the process does not go so far as in this case,
the separate capsules remaining imperfect anteriorly and
posteriorly. The lateral walls of the capsule, however, seem
to me to have as much (or as little) ‘organic connexion with
the pulp and attachment to its base” as in man, and the pro-
cess seems to correspond with something more than the “ first
and transitory papillary stage of the development of the mam-
malian teeth.” ¢

Each pulp is invested by a very distinct basement mem-
brane, whose continuity with that of the mucous membrane
of the follicle is very obvious. The epithelium of the follicle
forms a thick layer, which sometimes, when the upper wall
is stripped back, adheres to it—sometimes remains as a cap

* See Blake’s ‘ Essay,’ &c. 1801, in which the essential peculiarities of
the development of the teeth in the shark and skate, and their mode of
advance, are very well pointed out. He refers to Herissant and Spallanzani
as having anticipated him.

+ See Owen’s ‘ Odontography,’ p. 15.

M 2

152 HUXLEY ON THE DEVELOPMENT OF THE TEETH.

investing the papilla. Even when the latter does not take
place, shreds of the epithelium frequently adhere to the
papilla in the form of irregular, more or less cylindrical
nucleated cells; as often, however, the papilla, whether any
of the proper tooth substances be formed or not, has nothing
adherent to it, but presents a perfectly smooth sharp edge.
Other portions of the epithelium, particularly towards the
bottom of the follicles, are more or less altered and irregular,
Frequently assuming the form of a stellate tissue.

In the Skate, then, the follicle is an involution of the derm, the
papilla is a process of it, and the epithelium between the two
becomes metamorphosed sometimes into a peculiar stellate
tissue. The same essential relations prevail as before.

In Man, some confusion has prevailed with regard to the
homology of the various component parts of the tooth sae,
though they might be readily enough deduced from the mode
of development of the sac ; however, it is, | think, not at all”
difficult to obtain perfect demonstration upon this subject.

If a young tooth capsule be opened (say of a foetus at the
seventh month), whatever care may be exercised, it will
always be found (Hunter, Bichat) that a space filled with a
fluid exists between the inner surface of the capsule and the
outer surface of the pulp—the two are perfectly free from all
adherence to one another—+the only substance between them,
besides tle fluid, being a more or less abundant whitish matter
which sometimes adheres to the one and sometimes to the
other (see Goodsix, J. c.).

If the tooth he very young, a structureless membrane, the
m. preformativa of Raschkow (the basement membrane of
Bowman), may be traced over the whole surface of the pulp,
or if calcific deposition have already commenced, it may be
found readily enough at any rate in the lower unossified part ;
and it is not at all difficult to trace this in perfect continuity
on the walls of the capsule—in fact into its basement mem-
brane. ‘The best way of seeing this is by detaching the whole
sac from its alveolus, and then, laying it carefully open
in a watch-glass, turn the capsule carefully back, transfer
the whole to a glass plate, and cover it with a piece of thin
glass. The continuity of the basement membrane of the pulp
with that of the capsule is now evident enough under the
microscope.

The wall of the capsule is often folded, and sometimes I
have noticed villous processes, such as those described as
vascular by Dr. Sharpey.* Not unfrequently the basement

* See also Goodsir, /.¢. p. 17. In a child at birth “ the interior of
the sac had a villous, highly vaseular appearance, like a portion of

HUXLEY ON THE DEVELOPMENT OF THE TEETH. 1538

membrane of the capsule is quite naked, but ] have sometimes
observed a lining of short cylindrical nucleated epithelium
cells upon it.

I have said that a whitish substance lies between the base-
ment membrane of the pulp and that of the capsule. It is
delicate and friable, but frequently forms a more resisting
layer towards the pulp. On this surface I have found it to
be composed of a layer of elongated, more or less cylindrical
epithelium cells 1-1000th of an inch in length, with or
without nuclei, and adhering together in the direction of their
short diameters. On the surface towards the capsule, on the
other hand, this substance is composed of irregular cells
united into a network (jig. 7), and very similar to those
which have been described in the Skate. The structure of
this substance, and its relation to the basement membrane of
the pulp, and of the capsule, clearly indicate that it is
nothing more than the altered epithelium of these organs.*
It is the so-called “ enamel organ”’ of authors, and very wonder-
ful figures and descriptions indeed have been given of it in
various works upon the teeth. The only detailed,t and at the
same time, as it seems to me, completely accurate account I
have met with of this so-called enamel organ, is the very
clear and admirable description by Mr. Nasmyth, contained
in his posthumous work, ‘Researches on the Development,
Structure, and Diseases of the Teeth, 1849. The merits of
this gentleman have met with such scant justice that I can-
not do better than let them speak for themselves in this
place ; those who work over the subject hereafter will not
fail, I think, to acknowledge them as I have done.

injected intestinal mucous membrane.” See also p. 25 of the same ad-
mirable essay.

* Goodsir (‘ Edin. Med. and Phys. Journal,’ 1839) and Todd and
Powman (‘ Physiological Anatomy’) state very distinctly that the pulp
is an ordinary papilla, and the capsule an involution of the mucous mem-
brane, and the latter justly described the membrana preformativa of
the pulp as a basement membrane (p. 175), but they consider the
** stellate tissue ” and the enamel organ to be the “ wall of the.sac itself.”
Kolliker (‘ Mikr, Anat.,’ p. 101) expresses the same opinion.

t Mr. Tomes (‘ Lectures,’ &c., 1848) appears to me to have described
the enamel organ very accurately, but he has, I think, failed to distinguish
the proper enamel organ or epithelium of the sac from the submucous
cellular tissue—the latter is his ‘‘ reticular stage of the enamel pulp,” the
former his “ second stage”’ or “ stellate tissue,” while what he calls the
“‘ transition part,” p. 99, is, I think, the dense superficial layer of the
capsule, very well described by Mr. Nasmyth (wide infra) as “ the inter-
nal lamina of the dental capsule.”

Professor Kolliker (‘ Mikr. Anat.,’ p. 99 B) appears to me to have
fallen into the same error.

154. HUXLEY ON THE DEVELOPMENT OF THE TEETH.

Development of the Formative Organs of the Teeth, Follicular stage.—
“« At an early period of the follicular stage when the apex of the papilla
rises above the level of the surrounding fence of mucous membrane, a
small quantity of whitish matter may be detected in the groove between
the papilla and the follicle—this is the enamel organ. Not unfrequently
the whitish matter has the appearance of granules which seem to have
been separated from the surface of the follicle. These granular masses
have a pearl white aspect, and are soft and friable. Under the micro-
scope they are seen to be composed of cells which separate from one
another upon the slightest compression. The cells offer considerable
variety in respect of size and shape, some being small and round, others
large and flattened, and furnished at one extremity with a delicate
prolongation ; while others again are elongated and narrow, and have a
defined and regular margin. They contain nuclei and nucleoli, and are
covered on their interior by minute granules, which are also found in con-
siderable abundance in their interstices.”—p. 104.

‘‘ In the numerous examinations which I have made of the stages of
growth of the teeth here described, the enamel organs did not appear to
me to be attached either to the papilla or to the surface of the follicle.
This may probably arise from the circumstance that all the embryos
which I dissected had been kept for some time in diluted spirits of wine.”
—p. 105.

He then quotes Raschkow’s account of the structure in the
Lamb and Calf, and goes on to say,—

“ In my own investigations made with the aid of one of the best micro-
scopes of modern construction, and with a magnifying power of one-tenth
of an inch focal distance, I found the enamel substance to be composed of
cells of three different kinds.

‘“‘ The first kind of cells are found in the, interior of the organ, and
compose its loose, soft, and easily compressible texture. They are
flattened and triangular in form, and connected to adjacent cells by means
of delicate filaments prolonged from one of theirangles. These appendages
have no analogy with the filaments of areolo-fibrous tissue, as declared
by Raschkow. JI have seen them in connexion with the cells of other
tissues, and the error on the part of this observer must have arisen from
the use of low microscopic powers.

“ The second kind of cells are oval in shape, and form an envelope to
the preceding: they are situated both upon the superficial and deep aspect
of the latter.

“The third kind of cells occupy the deep stratum of the enamel organ,
lying in contact with the dental papilla. They are narrow and oblong in
shape, and are arranged closely side by side; one of their extremities
being in relation with the papilla, the other being directed outwards.
They are firmly connected together, and have a radiated position in
respect of the papilla. It is to the layer formed by these cells that
Raschkow has assigned the name of enamel membrane. ‘Taking this view
of the construction of the enamel organ, I cannot perceive any grounds for
the division of it into two parts suggested by the description of Raschkow.
It is obviously nothing more than a single organ, and the difference in
the form and arrangement of the cells must simply be regarded as a tran-
sition of the first and second kinds into those of the third—the latter
being in the state of preparation for the reception of the calcareous salts.

“The mucous membrane which rises in the form of a ring fence around
the papilla developed from the dental groove is the future dental capsule,
At an early period it is difficult to determine to what extent the internal

HUXLEY ON THE DEVELOPMENT OF THE TEETH. 155

surface of the growing follicle differs from mucous membrane. That it
does so may be inferred from the change in function which it assumes ;
and at a later period, when the follicle is about to close, the difference in
its organic character becomes strikingly obvious. For example, it is
white, silvery, loose, and rugous, and easily falls into folds, and, under
the microscope, offers the appearance of a number of minute cells possess-
ing characters widely different from those of the epithelium.

“ A portion of the internal lamina of the dental capsule, placed under
the microscope, shows it to be composed of layers of cells loosely arranged,
and separated by interspaces equal to half the diameter of the cell. The
cells are oval in shape, and provided with one or more distinct nuclei, and
they contain in their interior a small quantity of granular matter. The
internal lamina of the dental capsule maintains but a slight degree of
adhesion with the enamel organ, and possesses no vessels. Subjacent to it
is a network of blood-vessels, supported by a web of areolo-fibrous tissue
formed by the interlacement of tine homogeneous filaments, among which
nucleated cells are not unfrequently observed.”—p. 107.

Saccular Stages —When the sac closes—

*‘ The space between the pulp and the sac becomes filled with a fluid
secretion which distends its cavity, and often produces a conspicuous
enlargement in the situation of the tooth.”—p. 108.

**On the part of the capsule corresponding with the sides and neck of
the crown is a flat portion of the enamel organ, which is destined to the
formation of the enamel in that situation. ‘This lamina has a well defined
inferior border at a later period in the growth of the enamel organ ; the
appearance which it presented of a gelatinous mass is lost, and the
substance contracts into a membranous layer. At this time also the
prominences from the internal surface of the capsule have enlarged, and
have become vascular and more closely adherent to the enamel organ.
Some writers have inferred from this appearance that the enamel organ
itself becomes vascular,* but this is not the fact; it is simply that portion
of the capsule which lies in contact with the enamel organ that presents
the vascularity referred to.

“The dental capsule being originally, as we have seen, a production of
the mucous membrane of the alveolar groove, is attached by its external
surface to the neighbouring soft parts by means of loose areolo-fibrous
tissue. Blood-vessels ramify very freely in this tunic, and from the
interlacement which they then form, numerous capillary loops are given
off, which extend into the superficial portion of the membrane. These
vascular loops are separated from the enamel organ by a delicate layer of
cells, the characters of which have been already explained.

** Not the least interesting of the features attendant upon the develop-
ment of the teeth is the relation which the capsule bears to the pulp and
to the tooth at various periods of its growth. In the follicular and early
periods of the saccular stage, previously to the commencement of the
formation of the ivory, the capsule is continuous with the base of the
dental papilla ;f and at a subsequent period, when the ivory of the crown

* Raschkow, in a note appended to his Researches, remarks that he has
observed the enamel organ to receive blood-vessels in certain parts, and
believes the parenchyma of the organ to be pervaded by capillary vessels.
The conclusion which he deduces from this observation is, that the enamel
organ was from the beginning joined to the capsule.

t It passes upwards over it, forming a distinct envelope, separated from
the layer of mucous membrane externally.

156 HUXLEY ON THE DEVELOPMENT OF THE TEETH.

forms a complete covering to the pulp, the same arrangement takes place.
But at a more advanced stage in the growth of the tooth, when its forma-
tion has proceeded beyond the limit of the crown, the capsule attaches
itself closely around the neck, and the connexion of the two structures is
so firm, that every attempt to effect their separation generally results in
the laceration of the membrane. The continued growth of the tooth
carries the capsule upwards with the rising alveolus to the under part of
the gum, which now stretches over it; when pressed upon by the surface
of the crown, it becomes atrophied and absorbed. No portion of the
capsule seems to pass down into the alveolus.”—p, 110.

Everything that I have seen confirms this admirable de-
scription as to matters of fact, and the only objections I shall
have to offer are to certain of Mr. Nasmyth’s conclusions,

In Man, then, as in the Skate, the Mackerel, and the Frog,
the tooth-pulp is a dermic process bounded by its basement
membrane ; the capsule is an involution of the derm, bounded
by its basement membrane; and the epithelium of these
organs lies between them, having in this case received the
name of “ Enamel-organ,” from the supposition that the enamel
was developed by the calcification of its elements. Of this,
however, I shall speak below.

There is an important difference between the dental sac of
the Calf and that of Man, which has given rise to much con-
fusion.

The “ actinenchymatous” tissue (Raschkow) of the former
does not at all correspond with the stellate tissue of the latter,
as has been assumed by all writers. In fact, in the Calf the
wall of the capsule is separated by only a very narrow space
from the surface of the pulp, and this space is completely
filled up by elongated cylindrical epithelium cells, which glue
the capsule to the pulp. Between the basement membrane of
the capsule and the alveolar wall, indeed, there is a very wide
interval (see Owen, J. c., pl. CX XII. a, fig. 9 ¢) occupied by
Raschkow’s actinenchyma. ‘This, however, is nothing more
than the loose submucous cellular tissue of the gum, similar
to that so well described by Mr, Nasmyth in the wall of the
capsule of man. Professor Owen says (J. c., Introduction,
p. lix.) that “no capillaries pass from the capsule into the
actinenchymatous pulp of the enamel.” But those which I
have examined do not bear out this statement; in fact, this
tissue presents one of the most beautiful and obvious vascular
networks with which I am acquainted.*

The true homologue of the “enamel organ” in Man there-
fore, in the Calf, is not the actinenchymatous tissue, but the thin

* Blake, who wrote in 1801, mentions the vascularity of the “ spongy ”

outer membrane of the tooth sac in the calf; he says it is * very
vascular,”—p, 81,

HUXLEY ON THE DEVELOPMENT OF THE TEETH. 157

layer of epithelium between this and the pulp. The general
relations of the different dental organs are, in other respects,
the same in the Calf as in Man.

I may now proceed to the second question. What is the
relation of the proper dental tissues to the three organs of the
tooth capsule ?

The answer is shortly this. Neither the capsule nor the
“Enamel-organ”’ take any direct share in the development
of the dental tissues, all three of which—viz. enamel, dentine,
and cement—are formed beneath the membrana preformativa,
or basement membrane of the pulp, In proof of this asser-
tion, I have to offer the following facts:—If, in a human
foetus of the seventh month, a dental capsule (say of an in-
cisor) be treated as I have above described, it will generally
happen that the surface of the young tooth-cap appears quite
smooth under a low power; or it may be that a few of the
elongated cells of the “‘organon adamantine” adheres to it.
In any case the adhesion is loose, and these cells may be
readily detached. Under a higher power the surface of the
upper part of the ossified cap appears reticulated, the meshes
being about 1-5000th of an inch in diameter. At the lower
part, where only a thin layer of dentine is formed, this ap-
pearance is less distinct, but the surface is somewhat wrinkled,
the wrinkles sometimes forming large and pretty regular
meshes, Viewed in profile, these wrinkles are seen to be
produced by the folding of a delicate structureless membrane,
which is continuous below with the membrana preformativa.
Towards the apex the tooth substance is almost too opaque
to make much out of it: the yellowish enamel, however, can
generally be distinguished from the dentine.

Now, while the object is under a low power of the micro-
scope, add some strong acetic acid ; a voluminous transparent
membrane will immediately be raised up in large folds from
the whole surface of the tooth. If the acetic acid be pretty
strong, it soon softens the substance of the tooth a little, and
then a slight pressure exhibits very distinctly the ends of the
enamel fibres under this membrane. ‘There can be no question
about this fact, as | have been able to demonstrate it to the
satisfaction of my friends, Mr. Busk and Professor Quekett.
The membrane is about 1-2500th to 1-1600th of an inch
thick, perfectly clear and transparent, and under a high
power exhibits innumerable little ridges upon its outer sur-
face, which bound spaces sometimes oval and sometimes
quadrangular, and about 1-5000th of an inch in diameter.
Furthermore, at its lower edge this membrane gradually loses

158 HUXLEY ON THE DEVELOPMENT OF THE TEETH.

all structure, and passes into the membrana preformativa.* In
fact, it is the altered membrana preformativa itself, no trace of
which has ever yet been found in the locality in which, ac-
cording to the prevalent hypotheses upon the development
of the teeth, it should .exist—viz., between the enamel and
the dentine.

In the Calff a similar membrane may be demonstrated, but
it is much more delicate, and I have not seen the peculiar
areolz upon its surface.

In the Frog, in which the layer of enamel is very thin and
structureless, the membrane (fig. 8) may be very readily de-
monstrated by the action of dilute hydrochloric acid, which in
this animal, as in the Mackerel and Skate, dissolves out the
enamel layer at once, while it only acts gradually upon the
dentine.

In all these animals I have examined the smallest teeth I
could find perfectly entire, without any rough mechanical
treatment, which I should think would destroy the delicate
membrane.

In the Frog, its surface is in parts reticulated, as in Man;
in the Mackerel and Skate (jigs. 9, 12) I have been
unable to find any such reticulation. In both these the
enamel forms a conical cap of almost structureless or ob-
scurely fibrous substance at the extremity of the tooth, while
the layer upon the body of the tooth is very thin.{ In the
Skate it is thick, dense, yellowish, structureless, and perfectly
smooth; but in the Mackerel it is developed upon the lateral
edges of the young tooth into sharp notched processes; lines
stretch across the body of the tooth from these, not unlike
the contour lines one sees on the enamel of a young human
tooth.

A membrane, corresponding with that which has been de-
scribed in the human subject then, is also found in members
of each of the other groups of Vertebrata which possess teeth.
In the human subject, and in Mammals, this membrane was

* It is stated, by all the writers on the subject whom I have consulted,
that the membrana preformativa is the first portion of the tooth which
ossifies. ‘This statement, however, is never supported by evidence; and
my own observations lead to precisely the reverse conclusions.

t Sce Hassall, Micr. Anatomy, p. 318.

$ As this “ dense exterior layer” may be dissolved out by dilute acid,
leaving the “‘ membrana propria of the pulp,” which is very much thinner,
standing, it is quite clear that it is not “formed by the calcification of
the membrana propria of the pulp, which therefore precedes the formation
of ordinary dentine.”—( Odontography, p. 17). Why should it not be
called enamel? It has at least as much claim to this title as that of the

lrog,

HUXLEY ON THE DEVELOPMENT OF THE TEETH. 159

discovered, and very accurately figured and described, four-
teen years ago (that is, in January, 1839, in the ‘ Medico-
Chirurgical Transactions), by Mr. Nasmyth, under the name
of the “ persistent capsular investment.” No question has
ever been raised as to the right of Mr. Nasmyth to this dis-
covery ; but it is remarkable, that neither in Professor Owen’s
‘ Odontography,’ which is the first subsequent work upon the
teeth, nor in Professor Kélliker’s ‘ Mikroskopische Anatomie,’
which is the last, is there any notice of Mr. Nasmyth’s dis-
covery. Kdélliker, indeed (/. ¢., pp. 76, 77), describes the
structure as ‘‘ schmelz-oberhautchen,” but his description
is not so good as that of Nasmyth, and he states that it does
not extend over the cement—Nasmyth having shown that it
does. Unfortunately, however, the latter, like all who have
succeeded him, misled by the supposed mode of development
of the enamel from the enamel-organ, imagined that, as the
“‘ persistent capsule” was outside the enamel it could be
nothing else than the membrane of the dental capsule; and
hence the erroneous description of the adherence of the latter
to the crown of the tooth, which I have already quoted. Had
he chanced to examine a tooth before its eruption, he would
at once have seen the incorrectness of his hypothesis.

Since then this “ Nasmyth’s membrane” is identical, on
the one hand, with the persistent capsule which lies external
to both enamel and cement, and, upon the other hand, with
the preformative membrane of Raschkow, or otherwise with
the basement membrane of the pulp; it is clear that all the
tissues of the tooth are formed beneath the basement membrane
of the pulp; in other words, they are all true dermic struc-
tures—none epidermic.*

The third problem was, the relation of the histological ele-
ments of the soft parts (that is, as we now see, of the pulp)
to the Dentine, Enamel, and Cement.

Three theories have been prevalent as to the mode of de-
velopment of the dentine. The first, the old excretion theory,
need not be considered here, as it has been given up on all
sides, The second, the Conversion theory, consists essentially

* That the enamel is not formed directly from the enamel pulp might
have been concluded from Professor Goodsir’s observations (J. ¢., p. 25).
He says, “‘ The absorption (in the granular matter) goes on increasing as
the tooth substance is deposited, and when the latter reaches the base of
the pulp, the former disappears, and the interior of the dental sac assumes
the villous vascular appearance of a mucous membrane. This change is
nearly completed about the seventh or eighth month.” It will not be
said, however, that the growth of the enamel ceases at the seventh or
eighth month.

160 HUXLEY ON THE DEVELOPMENT OF THE TEETH.

in the supposition that the dentine is the “ossified pulp ris
that the histological elements of the pulp become calcified
and converted directly into the dentine—the arrangement of
the elements of the dentine depending upon that of the
elements of the pulp. This is the doctrine maintained by
Blake, Schwann, Nasmyth, Owen, Tomes, Henle, Todd and
Bowman, and, more or less doubtfully, by Kolliker and
Hildebrandt.* The third theory is that contained in the
remarkable phrase of Raschkow.

** Postquam ... fibrarum dentalium stratum depositum est (quoted by
Schwann) idem processus continuo ab externa regione internam versus
progreditur germinis dentalis parenchymate materiam suppeditante... .
Converse fibrarum dentalium flexure que juxta latitudinis dimensionem
crescunt, dum ab externa regione internam versus procedunt sibi invicem
apposite continuos canaliculos effingunt, qui ad substantie dentalis
peripheriam exorsi multis parvis anfractibus ad pulpam dentalem cavum-
que ipsius tendunt, ibique aperti finiuntur novis ibi quamdiu substantiz
dentalis formatio durat fibris dentalibus aggregandis inservientes.”

The dentinal substance, that is, is deposited within the
pulp beneath the membrana preformativa in definite masses
(Raschkow calls them fibres, to which, indeed, under a low
power they have a remarkable resemblance), the gaps between
which eventually constitute the dentinal tubules. This, if a
name be wanted, might be called the Deposition Theory, and
is especially characterized by its asserting that the histological
elements of the pulp do not enter as such imto the dentine.
The following description of the young dentine in the human
subject holds good for all the animals which I have examined ;
and if it be true, I think the incorrectness of the Conversion
Theory necessarily follows.

To justify my own method of procedure, however, I am
necessitated to remark that I have been unable to verify the
statement of Professor Owen (J. c., Introduction, p. xxxix.), that
the teeth of Man “will not yield a view of the cap of new-
formed ivory and the subjacent pulp in undisturbed con-
nexion by transmitted light with the requisite magnifying
power.’ Qn the contrary, 1 have found it sufficiently easy,
by cutting off the half-ossified cusp of a young molar, or
eyen by submitting an entire canine or incisor to slight pres-
sure, to obtain a most distinct view of the pulp in undisturbed
connexion with the dentine, and in a profile view. Indeed,

_* Dr. Sharpey, on the other hand, with characteristic caution, after
citing the statements of some of the advocates of the Conversion Theory,
adds, ‘* We must confess that, after a careful examination of the human
teeth, we have been unable to discover any of the above-mentioned changes,
except the enlargement of the more superficial cells of the pulp, and their
clongations in the immediate vicinity of the dentine.”—Quain and Sharpey,
)p. U8s,

en ©.

HUXLEY ON THE DEVELOPMENT OF THE TEETH. 161

had other observers adopted this method, I do not think they
would have been led to consider the lacunze in young den-
tine, whose true nature was demonstrated by Raschkow, as
metamorphosed nuclei of the pulp.

When the ossifying boundary of a tooth-pulp is examined
in the way which I have here pointed out, it is seen that where
dentification has not begun, the membrana preformativa is in
immediate contact with the substance of the pulp, composed
of a homogeneous transparent base, in which closely-arranged
“nuclei”? are embedded. ‘These are rounded or polygonal,
apparently vascular; contain one or more granules, and are
about 1-2500th—1-3500th of an inch in diameter. Passing
towards the ossifying edge, we see in the profile view a clear,
more strongly refracting layer, gradually increasing in thick-
ness, which begins to separate the proper substance of the pulp
from the membrana preformativa. This is at first quite struc-
tureless to all appearance, both in this view and in one per-
pendicular to its surface. When it has attained a thickness of
1-2500th of an inch, however, it acquires a sort of mottled
appearance in the profile view, while superficially numerous
very minute irregular cavities, about 1-5000th of an inch apart,
present themselves (fig. 5). Ina thick portion of the den-
tine (3-5000ths) these cavities are very readily seen in the
profile view to be elongated into canals; superficially they
are rather larger ; and as they run somewhat obliquely, 1t may
very readily happen that, unless the focusing of the micro-
scope be very careful, one will run into the other, and so
produce the appearance of fibres described by Raschkow.

This young dentine is as transparent as glass. No trace
of “nuclei” can at any time be discovered in it; the bodies
which have been described as such being, as I have said,
simply lacunz ; nor, if strong acids be used so as to dissolve
out the calcareous matter, are any nuclei brought to light,
though those which exist in the pulp became much more dis-
tinct, and even coarse, in their outlines, Again, if to a pulp
thus treated, a weak solution of iodine be added, the nitro-
genous substance of the pulp is immediately coloured deep
yellow, the nuclei themselves becoming brown ; but the den-
tine remains pale, except that here and there a yellow pro-
cess of the matrix of the pulp may be seen stretching a little
way into one of the canals of the dentine. I have only ob-
served this, however, once. I believe that these facts afford
sufficient demonstration that the pulp is not converted directly
into the dentine, and that, the structure of the latter does not
depend upon the calcification of pre-existing elements.

lam the more satisfied with this negative evidence, as in

162 HUXLEY ON THE DEVELOPMENT OF THE TEETH.

young bone it is easy to demonstrate the “nuclei” in the
lacune by the aid of acids, &c.

As to whether the perpendicularly crowded “nuclei” of
the pulp under the dentine disappear, or whether they are
merely pressed inwards, | cannot pretend to offer a decisive
opinion. The former supposition, however, if we may judge
by the analogy of bone, appears more probable. Dentine,
in fact, might be considered as a kind of bone, in which the
lacune are not formed in consequence of the early disap-
pearance of the nuclei, whose persistence for a longer or
shorter period appears to be the sole cause of their existence
in bone.*

Still less can the enamel be produced by any conversion of
a cellular structure. Between it and anything which can be
called a nucleated cell it has on the outer side Nasmyth’s
membrane ; on the inner, the layer of dentine, which in Man
is formed before it. The fibres of which it is composed are
structureless, and almost horny ; and | think we must be content
for the present to consider its existence and its structure as
ultimate facts, not explicable by the Cell Theory. It is par-
ticularly worthy of notice that in the Skate the dermal teeth or
plates on the upper surface of the head have as distinct a layer
of enamel as those of the mouth, though in this case there is
most assuredly neither rudimentary capsule nor “ enamel
organ,”

In a morphological point of view, the relations of the cement
show it to be homologous with the enamel. In a very beau-
tiful section of a human tooth from Mr. Busk’s cabinet, the
upper portion of the cement exhibits in places a very distinct
transverse striation, resembling its perfect enamel. But the
transition of the one structure into the other is best exhibited
in the young Calf by the cement of the fang of a molar which
had not cut the gum. Here it is a white substance, from
which generally a fitting section can be cut only with some
difficulty, in consequence of its triability. The layer is about
1-40th of an inch thick, and consists of an external delicate
structureless Nasmyth’s membrane; internal to which three-

* I have here no space to enter into the discussion of the various
hypotheses and assertions, respecting the development of the dentine,
made by the various authors whose names I have cited. I trust it will
not on that account be supposed that I have neglected to make myself
acquainted with them. But there are two statements to which I must
refer in confirmation of my own view. ‘The one is that by Dr. Sharpey
already quoted: the other is the very just declaration (in italics) by Pro-
fessor Kolliker (Handbuch, p. 386), that “* the most careful investigation
oo no trace of any elongation of nuclei” in the peripheral cells of

1@ pu p-

HUXLEY ON THE DEVELOPMENT OF THE TEETH. 163

fourths of the thickness of the layer are formed by parallel
fibres 1-5000th of an inch in diameter, quite structureless,
and completely resembling enamel fibres, but absolutely
enormous (as much as l- 60th of an inch) in length. These
fibres were softened and rendered pale by the ac Gon of caustic
ammonia, ‘The inner fourth of the layer of cement was com-
posed of an inextricably interlaced body of such fibres,
united into a mass, which in some places was almost homo-
geneous, by calcareous salts, and containing here and there
lacunze 1-1600th of an inch in length, similar to those of
bone. That this structure was the young cement is certain,
inasmuch as no enamel is formed on the fang of the tooth, to
say nothing of the presence of the lacune. On the root of
the fang of the molar in front of this, which had cut the gum
some time, and had come into use, the cement had the ordi-
nary structure. It may be worth while to add that in these
teeth the capsule, though closely connected with the outer
surface of the fang, could be readily stripped from it, and
then exhibited a lay er of epithelium upon its inner surface,
showing clearly that the cement was not derived from its
ossification.

It may be concluded, then,—

1. The teeth are true dermic structures, formed by the de-
posit of calcareous matter beneath the basement membrane of
a dermic papilla, or that which corresponds with one.

2. Neither the capsule nor the ‘enamel-organ,” which
consists of the epithelium of both the papilla and the capsule,
contribute directly in any way to the development of the dental
tissues, though they may indirectly.

3. The histological elements of the pulp take no direct
part (except, perhaps, eventually in the cement) in the deve-
lopment of the dental tissues, becoming either absorbed or
being pressed in by the gradual increase of the latter. The
Conversion Theory is, therefore, as incorrect as the Excretion
Theory, and the dentine is formed, not by ossification of the
histological elements of the pulp, but by deposition in it,
“‘ parenchymate materiam suppeditante.”

I have already exceeded my limits, and I must, therefore,
dismiss my last point very concisely. ‘The true homologues
of the teeth in Man are, I think, the Hairs. As Hildebrandt
says, “ As the Hairs in their bulb (sac), so the Teeth are de-
veloped in their capsules.” The stage of the free papilla,
which does not occur in the hairs of man, is absent in the
teeth of the Mackarel and Frog, and, indeed, it would seem
in the permanent dental capsules of man also.

Substitute corneous matter for calcareous, and, the Tooth

164. HUXLEY ON THE DEVELOPMENT OF THE TEETH.

would be a Hair. The cortical substance of the hair contains
canals not unlike those of the dentine; its relation to a
dermal papilla is the same as that of the dentine:* for
although it is universally stated to be such, I think it can be
shown that the hair shaft is not an epidermic structure, but a
dermic one.

Again, the so-called cuticle of the hair corresponds in all
respects, except absolute and relative size, with the enamel
—its inner layer with the enamel proper—its outer with Nas-
myth’s membrane. On the root of the hair the cuticle
is not continuous with the proper epidermic cells, but with
a structureless membrane, which occupies more or less dis-
tinctly the place of a membrana preformativa. ‘The two root-
sheaths, again—true epidermic structures, but which do not
enter all into the construction of the hair proper—represent
the altered and unaltered portions of the “ enamel-organ.”

Hairs and Teeth, then, are organs in all respects homolo-
gous, and true dermal organs. Under the same category,
probably, will come Feathers and the Scales of fishes.

The Nails, on the other hand, seem to be purely epidermic,
at least according to Kélliker’s account of their development
(l.¢., p. 119); and in that case they are the homologues of the
root-sheaths and enamel-organs of Hairs and Teeth.

* See Todd and Bowman, p. 175.

(7SE6D"*)

On the Photographic Delineation of Microscopic Oljects by
Artificial Illumination. By Grorcr Suapzort, Esq.

Tue application of Photography to the purpose of delineat-
ing microscopic forms I have for some years entertained as
a favourite project; but some practical difficulties of mani-
lation deterred me from putting it to the test until quite
recently, when a sufficient stimulus was applied in the beau-
tiful specimens both on paper and glass exhibited in the
month of October last, at the Microscopical Society of London,
by Mr. Joseph Delves, of Tonbridge Wells. Of the excellent
promise for a highly valuable adjunct to microscopic science,
the proofs in the present Number of the Journal will afford
your readers an opportunity of judging.

As it is. not my intention to enter into particulars of the
rise and progress of this art as connected with the microscope,
I will only observe that the earliest microscopic photographs
which I had the pleasure of seeing were some Daguerreotypes
executed by Mr. Richard Hodgson by the aid of the direct rays
of the sun; and for these I believe he is entitled to claim the
honour of having been the first to produce a picture of this
kind.

But however beautiful the sharpness and detail of pictures
upon metallic plates, there are many causes to confine the
practice of the Daguerreotypic art within such very contracted
limits as to render it of but little use to the microscopist ;
whereas the increasing beauty and sensibility of the Collodion
process renders it a much more encouraging medium for fur-
ther experiment in this direction, besides offering the addi-
tional inducement of enabling one to transmit duplicates upon
paper to others engaged upon similar observations at a distant
part, by which comparisons of much value can be made, and
without the expense and inconvenience of having to execute
duplicates from the objects themselves.

As it happens that the great majority of the followers of
microscopic science are mostly engaged in professional or
other business pursuits during the day-time, and in most
instances at a distance from home, it occurred to me that if
artificial light could be made to act sufficiently energetically
to produce microscopic pictures, it would be a very consider-
able advantage to a large number of persons who would other-
wise not be able to avail themselves of so excellent an assistant
as the photographic art ; and further, that to render it practically
useful, it must be done by an illumination readily accessible
and inexpensive ; 1 therefore determined to institute a series of
experiments with this end in view, and having availed myself

VOL, I. N

166 ON THE PHOTOGRAPHIC DELINEATION

of all the hints thrown out by Mr. Delves, Mr. Hogg, and
others, at the Microscopical meeting in October, after very
many failures and no small amount of trouble, I at length was
fortunate enough to meet with such success as, in my opinion,
to offer very considerable encouragement for further operations
with a reasonable hope of a really useful result; and at the
meeting of the Microscopical Society in November last I had
the pleasure of exhibiting a picture of a Fly’s Proboscis, pro-
duced by the aid of a very small camphine lamp. In the
hope of enlisting more labourers in this field of research, I
purpose detailing the ‘‘ modus operandi” which I have found
most successful ; trusting that, in a short time, the little seed
thus sown may bring forth an abundant harvest.

I would premise that I do not advocate photography in
microscopic, science as a rival that will supersede the draughts-
man, except in certain cases; and although it may in very
many instances do so, it will most assuredly make much more
work than it takes away from those who follow the occupation
of a microscopic artist.

When the object to be delineated is flat and moderately thin,
as compared with the necessary power in use, a very excellent
picture may be produced without any aid from the limner;
but where the object is not so formed—although when under
microscopic examination the mind can readily acquire a cor-
rect knowledge of the form by focussing up and down—it is
evident that from the very construction of a good objective a
picture can only be obtained in one plane at a time, and it will
then be necessary to take several pictures in different planes,
and call in the artist’s aid to unite the productions. The
immense amount of time and labour that can be thus saved in
delineating subjects of an elaborate character can only be ap-
preciated by those who have attempted the production of
objects of this class.

_ It is scarcely necessary to enter into a preliminary explana-
tion of the photographic phenomena, as it is of very little use
for an entire novice in the practice of this art to commence
upon microscopic subjects; I shall, therefore, presume that I
am addressing those who understand the general principles of
photography, and shall therefore commence with

_The Arrangement of the Apparatus.—Place the microscope
with the body in a horizontal position, and screw on the
objective to be used, and fix the object in its proper position
on the object-plate of the stage by pressing down the sliding
spring-piece. ‘Turn the mirror aside or remove it altogether,
and having taken out the eyepiece, insert into the body a tube
of brown paper /ined with black velvet, in order to prevent the

OF MICROSCOPIC OBJECTS. 167

slightest reflection from the sides, which would infallibly spoil
every picture if allowed to operate. The lens should then be
removed from an ordinary photographic camera, and the latter
elevated so as to bring its centre in an exact line with the axis
of the microscope body, which must have its eyepiece-end
inserted in the place left vacant by the removal of the camera
lens, and that portion of the opening not filled up by the body
may be rendered impervious to light by a piece of black cloth,
velvet, or other similar material.

The lighted lamp must next be brought, so that the centre
of the flame is in the axis of the instrument, and its distance
must depend upon the focus of the lens used to concentrate
the light, for which purpose an ordinary convex lens of 23 to
3 inches diameter, with its flat side towards the lamp, is per-
haps as useful as any, provided a second plano-conyvex lens of
that focus is interposed near the object to concentrate the light
still more strongly. It is not necessary, or even desirable,
that an image should’ be formed of the source of light, and
consequently the spherical aberration in such an arrangement
as recommended is not detrimental, and may be advantageous.

The ground glass screen to receive the image being in its
proper place in the camera, the object may be brought toa
correct focus in the usual way with the coarse and fine adjust-
ment, and this cannot be done too accurately ; in fact, for
delicate objects, a means of magnifying the image is absolutely
requisite, and for this purpose a positive eyepiece, placed in
contact with the ground glass, is perhaps best.

Most achromatic objectives of the best construction are
slightly over-corrected (as it is termed) for colour, in order to
compensate for a small amount of under-correction in the eye-
piece, that is to say the violet and blue rays of the spectrum
are therefore projected beyond the red ones.

As it is ascertained that most of the photogenic or actinic
rays are located in the violet end of the spectrum, it follows
that with such alens as is used for the microscope, the chemical
focus will be somewhat more distant from the object than the
visual focus, and it therefore becomes necessary to make some
allowance for this difference.

This may be done in two ways, either by placing the sensi-
tive plate somewhat farther off than the ground glass on which
the image is received, or by altering the focus by the fine
adjustment ; the latter being the plan I prefer, as I find it
much more accurate.

The amount of difference between the foci probably varies
in every objective, even apparently of the same make, and

can only be ascertained by direct experiment, but the follow-
n 2

168 ON THE PHOTOGRAPHIC DELINEATION

ing may be some guide to those who wish to experiment upon
the subject.

An inch-and-a-half objective of Smith and Beck’s make
required to be withdrawn from the object after the correct
yisual focus is ascertained 1-50th of an inch, or two turns of
their fine adjustment.

A two-thirds of an inch object glass of same make wants a
withdrawal of 1-200th of an inch, or 4 a turn of the fine
adjustment, and

A 4-10ths of an inch, about 2 divisions, or 1-1000th of
an inch farther off. With the 1-4th, and higher powers,
the difference between the foci is so minute that it is practi-
cally unimportant. The above differences are those actually
existing in my own objectives, but, as before intimated, it does
not follow that they will be correct for others even of the
same makers.

Having arranged the apparatus, focussed, and made the
requisite adjustment for chemical focus, the ground glass may
be removed, and the sensitive plate placed in its stead.

As in all other photographic processes, the time of exposure
must be varied according to the power in use, the nature of
the object to be taken, and the amount of illumination, to
which must be added in the present instance the medium in
which the object is mounted, but from 1 to 10 minutes’ exposure
is generally requisite. An explanation of the last named
disturbing cause may probably be found in the beautiful dis-
covery of Professor Stokes of the property possessed by
certain transparent media of arresting the chemical rays.

Any account of the preparation of the collodion, &c. &e.
would be more fitted for a work on photography, and would
render the present paper much too lengthy : moreover there is
an abundance of information on photographic manipulatory
details readily accessible in numerous publications, such as
Mr. Robert Hunt’s Manual, Mr. Bingham’s, Mr. Archer’s, Mr.
Horne’s, Mr. Hennah’s, &c. &c. There are, however, one or
two points which it is as well to allude to. If the film of a
collodion picture be examined by the microscope, some
specimens will present an appearance very much resembling
condensed cellular tissue, such as that seen in the cuticle of
leaves, being apparently made up of flattened irregular
hexagonal cells ; while others seem to consist of an entirely
structureless amorphous mass; the latter sort of collodion is
most suitable for microscopic purposes.

The final fixation of the picture by removal of the iodide of
silver has a singular influence upon the result according to
the method employed, and advantage may be taken of this in

OF MICROSCOPIC OBJECTS. 169

order to improve the effect according as it is desired to pro-
duce glass positives or negatives; for though all collodion
pictures partake of both characters, one of the two should
always be predominant.

Of course a negative is most useful, because the drawings
can be multiplied upon paper almost ad infinitum, but for
certain objects the amount of detail when very delicate is in-
conceivably better shown upon glass than upon paper. If
then a negative picture be desired, it is best to develope with
the pyrogallic acid solution, and fiz with a solution of hypo-
sulphite of soda; but if, on the contrary, a positive picture is
the desideratum, the effect will be infinitely better by fixing
with a bath of the following, viz. :—

Cyanide of Potassium . : . » 13 drams.
Water 5 : ° . - a pinivs
Nitrate of Silver ‘ : . . 15 grains.

The cyanide to be dissolved in the water, and tbe crystals
of nitrate of silver added, which immediately cause a curdy
precipitate, but this is quickly redissolved, and the whole
becomes quite translucent.

By this method of fixing, the whites are very much purer
and brighter than when the hyposulphite is used, but the
pictures do not answer so well for printing from. A still
further intensity of the whites may be produced by developing
the picture with a solution of the proto-su/phate of iron, instead
of the pyrogallic acid, and afterwards fixing with the cyanide
solution ; there are, however, certain difficulties of manipulation
to overcome. The solution is made as follows :—

Proto-sulphate of Iron in Crystals 2 eg 87
Water. : . - by measure 10 oz.
Sulphuric Acid . : : Ass 1 cz.

This is best used by placing in a glass bath and totally im-
mersing the plate, which should be withdrawn the moment the
picture is perfectly developed, which will be in from 15 to
60 seconds, and it ought to be instantly plunged into a bath
of plain water sufficiently copious to dilute the adherent
moisture very considerably. The object of the bath being of
glass, is in order to see the development of the picture, as
every second it remains after it is fully produced, is to the
detriment thereof, by causing a sort of fogginess to appear all
over it.

When developed with the protosulphate of iron, the
pictures may be exposed to direct day-light before the final
fixing, without injury, in fact with positive benefit according
to Mr. Martin.

The causes most frequently operating to prevent the success

170 TEETH ON THE TONGUES OF MOLLUSCA.

of the process are, first, want of attention to the proper illumi-
nation; it is to this point more than any other that the utmost
attention should be paid, and I feel confident that by well
concerted measures to attain this requisite, we shall eventually
be able to obtain pictures in a tithe of the time now necessary ;
in the second place failures more often occur from over exposure
than from being too short a time; thirdly, want of allowance
for difference of visual and chemical foci.

In conclusion, I would observe that some experiments upon
the different light-producing substances would in all probability
well repay the trouble of testing their capabilities, as from
certain hints thrown out by Professor Stokes, there appears to
be a very considerable difference in the amount of actinic rays
emitted by differing combustibles, and it seems not improbable
that a well contrived spirit lamp may be found highly advan-
tageous to use while taking the impression, although its light-
giving properties are so defective. I hope shortly to be able
to resume this subject.

On the Teeth on the Tongues of Mottusca. By J. E. Gray,
PhD, FRCS S VEZ St Die, oe

Lister, Leeuwenhoeck, Swammerdam, Poli, Cuvier, Fleming,
Delle Chiaje, Verany, Eydoux, Souleyet, Van Beneden,
Oersted, and some other naturalists, have, at various and dis-
tant periods, described and figured the teeth on the tongues of
isolated species of Mollusca.

Dr. Troschel, in Wiegmann’s ‘ Archiv,’ 1836, 257, t. 9
and 10, and 1839, 177, t. 5, f. 8, describes and figures the
teeth of some German terrestrial and aquatic Mollusca. In
the same Journal, 1845, 197, t. 8, f. 6, the teeth of Ampul-
laria, and in 1849, 225, t. 4, he has described and figured
the teeth of some exotic Bulimi and Nanine.

The Rev. Mr. Berkeley, in the Zoological Journal (iv.
278), describes the teeth of Cyclostoma elegans.

Dr. Wyman, in the Boston Journal of Nat. Hist., has
described and figured those of Tebenophorus and Glandina ;
and Mr. Thomson, in the Annals and Magazine of Natural
History (1851, vii. 86, t. 3), has published a very interesting
essay on the dentition of British Pulmonifera.

MM. Quoy and Gaimard, in their large government work,
figured the teeth of several marine genera of exotic Mollusca ;
but, unfortunately, on verification, the figures of some of the
genera are so incorrect as to throw doubt on the others.

TEETH ON THE TONGUES OF MOLLUSCA. KL

Dr. Loven, in his very excellent paper on the Mollusca of
Scandinavia, made some important observations on the teeth
of some marine Mollusca; and in a special paper on the sub-
ject (Oversigt. af Kongl. Vetensk. Akad. Férhandl., 1847,
175) he describes and figures the teeth of the several orders,
families, and genera of Scandinavian Mollusca. He divides
the tongues he has seen into fourteen groups, and separates
the genera into families and sections, characterized by the
number, position, and forms of the teeth, which opened a
new series of characters for the systematic descriptions of the
Mollusca.

Messrs. Alder and Hancock, in their beautiful work on
British Nudibranchia, and Messrs. Hancock and Embleton,
in the Philosophical Transactions for 1852, have figured the
teeth of several British Nudibranchiate gasteropods; and
Dr. Troschel, in Wiegmann’s ‘ Archiv’ (1852, 152 t.), MM.
Eydoux and Souleyet, Voy. de Bonite, M. Oersted, and myself
in a paper in the Annals of Natural History for 1853, have
described and figured the teeth of some genera of marine
Mollusca which had not been before deseunenl

Mr. Hancock and Dr. Embleton (Phil. Trans., 1852, 211)
have described the development, wearing, and succession of
the teeth of the Dorides ; they observe, “ fie mode of growth
of the spiny tongues of Doris is evidently quite analogous to
the growth and advance of the teeth of the rays and sharks,
&e., or of the hoof and nails of Mammalia.”

Dr. Troschel, in the third edition of Wiegmann and Ruthe’s
‘Handbuch der Zoologie,’ Berlin, 1848, proposed to divide
the Gasteropods into four orders, according to the number of
the teeth on the lingual band, giving them the names of—
1. Tenioglossa ; 2. Toxoglossa; 3. Proboscidea; 4. Rhipido-
glossa.

In some observations on this paper (Annal. and Mag. N.H.,
1852, x. 411) I proposed to use the names of ‘iene aciias
as technical terms in the description of the families, and pro-
posed a new one, Ctenoglossa, for the numerous uniform teeth
of the Pulmonata and other genera; and in a paper on the
families of Ctenobranchiate Mollusca (Annal. and Mag. N. H.,
1853, xi. 124), where I have described some new forms of
~ teeth, I have extended the number of terms so proposed.

Believing that it will be useful to science to have a series
of terms to indicate the chief modifications of these teeth
which have been observed, I have sent you the following table
of them, illustrated with a figure of each form, and with a list
of the families of Mollusca which they characterize :—

I. Rhachiglossa. The lingual membrane has a single cen-

172 TEETH ON THE TONGUES OF MOLLUSCA.

tral series of teeth, as in the family Glaucide, Loven, t. 3,

/\

Fig. 1.—Yetus olla. Fig. 2.—Cymbiola Turneri.

I

Fig. 4.—Mangelia costata.

Fig. 5.—Chrysodomus antiquus. Fig. 3. -Conus, sp.

figs. 15, 16 ; Dotonide, Phyllirrhoide, Limapontiade of Nu-
dibranchiata ; and Volutide (figs. 1, 2), of Ctenobranchiata.

If. The lingual membrane, with two series of elongated
subulate teeth, one on each side of the central line.
a. Toxoglossa; the teeth elongate, straight, or spiral.
1. Conide ; teeth with a channel on the side and barbed.
(Fig. 3.)
2. near at ; teeth subulate, straight, simple.
ig. 4.)
6. Drepanoglossa ; the teeth curved, elongate, slender, com-
pressed, short, conical, strong. Philinide, Onchidoride.

III. The lingual membrane, with three series of teeth ;

central teeth simple,

A. Hamiglossa ; the lateral teeth versatile, attached by the
inner end, and capable of being bent over on each side
(Fig. 5); as

ee Buccinide, Olivide ; with the lateral teeth flat ;
ane

Lamellariade ; with the lateral teeth curved

TEETH ON THE TONGUES OF MOLLUSCA. 173

B. The lateral teeth bent towards the central one. Cavoli-
nide, Limacinade, Loven, t. 3, fig. 5,6. Amphisphysade,
Lovén, t. 3, f. 20.

c. Odontoglossa ; the lateral teeth fixed on the same plane
as the central ; immoveable (figs. 6 and 7); as

a. Fasciolariade ; the central teeth small, few-toothed ;
the lateral very broad, many-toothed. (Fig. 6.)

b. Turbinellide ; the central teeth moderate, largely toothed ;
the lateral moderate, few toothed. (Fig. 7.)

DANIO A AU

Fig. 6.—Fasciolaria filamentosa.

AAA

Fig. 7.—Turbinella cornigera.

Fig. 8.—Lepeta cceca.

IV. Oplatoglossa ; the lingual membrane, with siz series of
teeth, the central large, the lateral hooked, similar, (Fig. 8.)
Lepetade.

V. The lingual membrane, with seven series of teeth, the
central recurved at the top; the inner lateral, broader, re-
curved at the top.

Fig. 9.—Natica pulchella.

a. Tenioglossa ; the two other lateral, more or less conical,
incurved. (Fig. 9.)

Among Ptenobranchus Gasteropods :—Pterotrachide, Atlan-
tide, Paludinide, Ampullariade. Melaniade, Littorinide,
Valvatide, Naticide (fig. 9), Velutinide, Cypreade, Tricho-
tropide, Capulide, Calyptreade, Pediculariade, Cyclosto-
mide, Helicinide. Aporrhaide, Strombide, Loligide, Sepio-
lide, Octopide.

b. Dactyloglossa ; the two outer lateral teeth broad, divided

into many filiform lobes at the end (fig. 10), as Amphi-
peraside.

174 TEETH ON THE TONGUES OF MOLLUSCA.

NW,

>
=

4

Ys

Wy

Fig. 10.—Amphiperas Ovum.

VI. The lingual membrane, with numerous series of teeth.

a. Ctenoglossa. The teeth nearly uniform, similar; the

central distinct or wanting.

Among the Pulmobranchiata, as Veronicellide, Arionide,
Helicide, Auriculade, Lymneade. Amphibolide, Siphona-
riade, Cyclostomide (?), Helicinade, Onchidiade (Peronia).

Ptenobranchiata, as Janthinade, Scalariade (fig. 11), Cas-
sidide.

Pleurobranchiata, as Bullade, Aplysiade, Amplustride,
Acteonide.

Nudibranchiata, as Tritoniade, Doride, Diphyllidiade.

Pteropoda, as Clionide.

THACHER

Fig. 11.—Scalaria Turtoni.

B. LHeteroglossa central (rarely wanting); and inner lateral
teeth larger, often unequal, and variously shaped; the
lateral few, uniform, (Fig. 12.)

Amongst the Nudibranchiata, as Triopide (Triopa, and

Idalia). Lovén, t. 3, figs. 9,10, 11.
Pleurobranchiata, as Cylichna in Bullide. Lovén, t. 3,
fig. 21.
“Scutibranchiata, as Dentaliade, Chitonide (fig. 12); Patel-
lide (fig. 13); Tecturide (fig. 14).

Fig. 12.—Chiton cinereus.

TEETH ON THE TONGUES OF MOLLUSCA. rH

Fig. 14.—Tectura testudinalis,

Fig. 13.—Patella vulgata.

c. Rhipidoglossa. The central and inner lateral teeth
larger, often unequal and variously formed ; the lateral
teeth uniform, very numerous (fig. 15).

Turbinide, Liotiade, Trochide, Stomatellide, Haliotide,

Fissurellide. Neritide, all belonging to the first division of
Scutibranchiata.

Fig. 15.—Emarginula crassa.

I may observe, that, from the examination I have been able
to make of numerous kinds of Molluscs, the teeth offer
one of the best characters for their division into natural
families. I have such confidence in their permanence and
importance in the economy of the animals, that, if I found any
very considerable modification in the teeth of two genera
which had been referred to the same family, or, much more,
of two species, which had been referred to the same genus,
I should conclude that they had been erroneously placed in
such close proximity—as this modification must indicate an
important difference in the habits and manners of the living
species under consideration, which had before escaped our
observation.

The researches of Dr. Lovén, who has figured and described
the teeth of several Scandinavian species of Nassa, Chryso-
domus, Buccinum, §c.; of Mr. Thomson, who has described

176 COLOURLESS CORPUSCLES OF THE BLOOD.

the teeth of the various species of British Helices, Lymnea,
&c. Mr. Alder and Mr. Hancock’s researches on the teeth of
Nudibranchiata, and my own observation of the teeth of seve-
ral extra European species of Tritons, Murices, Fasciolarie,
&e., show that they offer such modifications in the form,
surface, and shape of the edges of the individual teeth as to
afford very good characters for the distinction of the species.

They will, therefore, most probably furnish most important
characters for the distinction of the species, especially of such
genera as Crepidula, Calyptrea, Patella, &c., which, from their
being long attached to particular places, change the external
character of their shells, and thence assume particular forms,
which have been regarded as distinct species.

I may add, that the lingual band bearing the teeth, or, as it
is termed, the “ tongue” of the Mollusca, makes a most in-
teresting object for the microscope; and I hope that persons
living in different parts of the globe will make a collection of
the tongues of the marine, terrestrial, and fluviatile Mollusca
in their neighbourhood, carefully marking the name of the
species to which they belong, as by so doing they will afford
a most important addition to the knowledge of Malacology.

Excess of the Colourless Corpuscles of the Blood (Leucocythemia)
occurring in Cases of Goitre. By Tuomas 8S. Hottanp,
M.D., Corresponding Member of the Société Anatomique
and of the Parisian Medical Society, Cork.

Tue impulse which the researches of Professors Bennett and
Virchow have given to the study of the histological alterations
in the Blood will be, I presume, sufficient excuse for the
publication of these observations ; and by confining myself to
a simple narration of facts I hope to secure the attention of
those who live in districts in which Goitre is of frequent
occurrence, and perhaps induce them to make, in all such
cases, a microscopical examination of the blood.

Case 1st.*—Johannah Nissl, aged 70, died in the Allge-
meine Krankenhaus of Vienna on the 17th of September,
1851; and dissection made, twenty-eight hours after death,
exhibited the following appearances. —

Body of the middle height, thin, pale; lower extremities

* T am indebted to the kindness of Professor Rokitansky for permission

to publish these cases, and the preparation, from case No. 1, is in the
Pathological Museum.

COLOURLESS CORPUSCLES OF THE BLOOD. 177

eedematous, pupils dilated, neck thick, thorax small, sternum
prominent, mamme atrophied.

Head and Neck.—Calvarium porous; a small amount of
coagulated blood in the superior longitudinal sinus ; pia mater
pale, opaque, and cedematous ; brain soft, with a half ounce
of serum in the ventricles, and small serous cysts on the
choroid plexus.

Neck and Thorar.—Thyroid gland so much enlarged that
its right half had acquired the size of a man’s fist, and the
isthmus that of an egg, while a process extending from the
latter lay upon the membrana obturatoria. The left half of
the gland reached as low as the right ventricle, extending
slightly across the chest at the superior opening of the thorax,
and measuring three inches in length by one in thickness.
The entire mass was made up of small lobules, having the
normal structure of the gland, through which passed large
and somewhat congested veins containing fluid blood. In
each pleural cavity about two pints of brownish serous fluid,
which had compressed the inferior lobes of both lungs, and
there was much mucus in the bronchi on each side. Two or
three ounces of serous fluid in the pericardium ; general dila-
tation of the heart’s cavities, more especially the right
ventricle, and its base lay a little lower than usual. Pul-
monary artery dilated to half again its normal size, while the
heart’s cavities contained much fluid, or but imperfectly coa-
gulated blood; valves healthy.

Abdomen.—Right lobe of the liver somewhat enlarged, and
presenting the so-called nutmeg appearance; in the gall
bladder a few drops of yellowish thin gall, its mucous mem-
brane being thickened and cedematous. Spleen normal in
size, colour, and consistence. Kidneys rather large, and the
cortical substance of a yellowish brown colour. Cavity of
the uterus exceedingly small, with the internal orifice of the
cervix closed.

Microscopical Examination.—The spleen was most carefully
examined, and appeared perfectly free from all trace of
diseased action. The fluid and partly coagulated blood taken
from the left ventricle exhibited a fine demonstration of that
state to which Professor Virchow gives the name of Leu-
keemie,* and Dr. Bennett+ that of Leucocythemia, the colour-
less corpuscles being about seven or eight times more
numerous than they appear ordinarily in healthy blood, and

* Archiv fiir pathologische Anatomie und Physiologie. 1852. vol. ‘v.
p. 43.

t+ On Leucocythemia, or White Cell Blood. Edinburgh. 1852.

178 PRACTICAL APPLICATION OF PHOTOGRAPHY.

I had an opportunity of having this observation confirmed by
my friend Dr. Robert MacDonnell of Dublin, who was at
that time in Vienna.

Case 2nd.—I regret exceedingly having lost the notes of
this most interesting case, and in order to avoid mistakes I
will only state that, in an autopsy, made in the Allgemeine
Krankenhaus, in October, 1852, on the body of a woman, aged
about 50, the thyroid gland was found enlarged to four or five
times its usual size, while the spleen was in every respect
normal, I took blood from the abdominal aorta immediately
above its bifurcation, and examined it with Dr. Heschl (first
assistant to Professor Rokitansky), expecting to find in ita
well marked excess of the colourless corpuscles, but 7 pre-
sented no such appearance, while blood taken from the pulmonary
artery contained so great an excess of these corpuscles that they
filled the greatest portion of the field.

It would be of course quite useless to attempt generalizing
from two cases, and I would only suggest that, in all similar
researches, the venous and arterial blood of the pulmonic,
hepatic, renal, and glandular systems be examined sepa-
rately, and that the account of the autopsy be as minute as
possible, as this state of the blood may be connected with
very many diseased conditions,

On the Practical Application of Puorocrapuy to the Iilustra-
tion of Works on Microscopy, Natural History, Anatomy, §c.
By Samus Hieutey jun.

Many scientific phenomena, when first discovered, either from their
remarkability or beauty, have excited much interest in the popular
mind, but have only been regarded by it as pleasing toys, till in
the course of time their practical value has been discovered, and
they have been arranged thereafter in the list of applied sciences.

Such was the globe of water, magnifying in distorted form the
fly or flower, till in the hands of science it sprung into that exquisite
refinement on optical knowledge, ‘‘ the microscope,” that discoverer
of hidden worlds and life, and the seat or form of disease within the
inmost walls of the human frame. Such the kaleidoscope, the tin
case with its bits of coloured glass, regarded long, only as a
wonder from the fair, till in practical hands we find ourselves in-
debted to its aid for many of the beautiful geometric designs which
ornament our walls or floors.

So likewise was the camera-obseura, the discovery of Baptista
Porta, of Padua, till the progress of chemical knowledge discovered
to us the means of fixing its fleeting shadows; and even then its
product, together with its adjunct, the stereoscope, was little

PRACTICAL APPLICATION OF PHOTOGRAPHY. 179

thought of in its most valuable practical bearings ; but of late this
has rapidly impressed itself upon us, and we cannot as yet see the
limits of its utility.

In Microscopy, Natural History, Physiological and Pathological
research, what an invaluable agent will Photographie art prove ;
for Nature here depicts herself with her own pencil, and, in all
probability, ere long from her own palette ; and in this resides one
of its greatest values, for truthfulness is insured, and our studies
delineated with a faithful and unbiassed hand; and with what
minuteness of detail, the photographs in this Journal bear witness.
With regard to good photographs from the microscope, as we have
presented to our view what the eye itself would only see if directed
to the field of that instrument, we may expect many valuable
records of histological research soon to be in circulation, to elicit
further investigation.

In delineating the peculiarities of the Geological features of a
country, or of its Flora and Fauna especially, where species that
could not be acclimatized to other regions are concerned, the
naturalist will appreciate its aid.

To the old complaint of the surgical anatomist, that little can be
gained from flat plates, a new atlas may be opened by the applica-
tion of stereoscopic principles to photographs of well-dissected
surgical parts.

To the physician it offers a means in many cases of conveying to
the student an idea of the ‘“‘ Physiognomy of Disease,” as already has
been shown by Dr. Diamond’s interesting collodion series of ‘ Types
of Insanity ;’ whilst in the accident ward, or the operating
theatre, the exact delineation of many a curious and interesting case
might, in a few seconds, be added to the records of its hospital, when
time and the restlessness of the sufferer would not permit a drafts-
man to exercise his art.

Convinced of the value of this beautiful art, the offspring of phy-
sical and chemical science, it is with a considerable degree of grati-
fication that, as one of the Publishers of the Microscopic Journal,
I am enabled to lay before the world in the plate which accom-
panies Mr. Delves’ paper its first practical application as a printing
process to the illustration of scientific literature, a field where it
will be mostly appreciated. And it is to the principles involved,
and the processes and apparatus employed, that I devote this paper,
for the information of those of our readers who may be unacquainted
with the details of Photography.

Photographic phenomena are dependent on the power of certain
rays, of which white light is composed, to effect the decomposition
of certain chemical bodies when presented to their action.

When white light is decomposed by the refracting influence of a
glass prism, it is resolved into a spectrum, which appears to be con-
stituted of seven rays, viz., violet, indigo, blue, green, yellow, orange,
and red; and the experiments of Sir John Herschel and Professor
Stokes prove the further extension of the violet rays into lavender
and spectral blue rays, and the red into a crimson ray, though these

180 PRACTICAL APPLICATION OF PHOTOGRAPHY.

are not visible to the unassisted eye. Sir David Brewster has, how-
ever, proved that this spectrum consists only of three primary rays,
blue, yellow, and red, which overlap each other, and thus by their
combination produce the other spectra. These primary rays may
be recognized in every part of the visible spectrum, and each seems
to be possessed of a different physical property: thus Thermotic,
calorific, or heating effects reside in the red rays, Light or luminous
effects in the yellow rays, and the Actinic or chemical effects in the
violet and the rays beyond it.

Photography (light-drawing) and Heliography (sun-drawing) seem
therefore to be inappropriate terms, since the light-giving rays are
by experiment shown not to be the chemical agent in the pheno-
menon, and artificial light produces actinic effects as well as the
sun. But as, whenever photographic effects are produced, actinism
is the agent, I would venture to suggest that the term Actinography
would appear to be most correct.

When surfaces prepared with agents sensitive to the actinic rays
are exposed to light, a molecular change sets in, and the surface
darkens all over; if, however, we protect any part, as by inter-
posing a piece of black lace or a transparent print, we obtain a
faithful outline of the first and an imprint of the second; but in
both instances the natural appearance is reversed, for the parts
exposed most to the light darken, whilst those parts protected
remain white ; thus the black lace placed on light paper appears
white on a dark ground ; whilst in the picture all the lights appear
as shades, and the shades as lights. Such prints are called Negatives,
and wherever this interchange of blacks for whites or lights for
shades occurs, the result belongs to this class. If, however, we
again print from these, the dark ground or shades protect the
surface they are laid on, and they then resemble the originals; such
are called Positives, and this term is applied in all cases where the
lights and shades are represented as in nature.

When we are operating on transparent media, this power of
reversing natural effects is of the greatest value, as it presents us
with the means of obtaining what is analogous te engraved plates,
from which we may print numerous copies, having all the effects
true to nature ; and it is to this circumstance that the Collodion
Process offers such advantages, on account of the transparency,
together with the modulations and depth of tone of the reversed or
negative pictures obtained.

It is to the production of Collodion negatives in their application
to natural history and anatomical subjects, and the method of print-
ing positives from them, that I devote the following description of
the various operations ; and although these are described as when
conducted under the most favourable conditions, this course is pre-
ferred, that a guide may be given to others as to the general prin-
ciples of the arrangements necessary, but which may be modified
according to the position and circumstances under which they may

be placed, or the extent to which they may feel inclined to carry
their experiments.

ENGRAVING, OR TAKING THE NEGATIVE. 181

ENGRAVING, OR TAKING THE NEGATIVE.

The Operating Room, wherein the negative plate is taken,
should be situated at the top of a house in a clear atmosphere ; if
possible, it should command a northern and southern aspect : where,
however, only one aspect can be obtained, the northern is preferable,
as it is exempt during the greater part of the day from the direct

-rays of the sun, and the actinic action over different times of the
day is more uniform from this direction. ‘This is divided into two
compartments,—one, being the light room, contains the Object Table,
the Background and Indicating Frame; the other, the dark room,
contains the Camera, the table, sink, and necessary materials for
coating, developing, fixing, and washing the plate.

The Light Room is built of glass, with the exception of a
skirting, which rises about two feet from the floor. Within the
panels are fixed rollers with black and white blinds, arranged so
as to give the operator a thorough command over the direction and
amount of light admitted, as may be readily understood by reference
to fig. 1.

Whe Object Table I have planned (T, fig. 1,) is so contrived on a
cylindrical pedestal, that the object can be raised and lowered, or
turned to one side or the other, with facility, so that different parts can
be arranged at any angle that may be required, as when taking
an anatomical view from a dead subject.

Whe Back-ground (G)_ usually consists of a short-napped
blanket, or a piece of nankeen cloth stretched on a frame. This
is suspended by rings on the rods RR, which run across the sides
of the room, so that it admits of being adjusted at any distance
from the object; it may either hang perpendicularly, or gradually
slanting from the object, which gives the appearance of a receding
background to the picture. The best effect, however, is produced
by using a very long and rough napped blanket, placed from three
to five feet behind the object; and whilst the picture is being taken,

VOL. 1. o

182 PRACTICAL APPLICATION OF PHOTOGRAPHY.

swinging it from right to left by means of a cord attached to the
frame: this produces a clear transparent background, which throws
the object out into bold relief with excellent effect.

Whe Endicating Frame (I, fig. 1) I have contrived, consists of a
broad, flat, black wooden frame, on the sides of which are painted
white letters or numbers, and a fine wire, having free movement,
corresponds to each letter or number, so that, if its end is dropped on
any particular part of the object, we can refer to it by giving the letter
or number at its origin on the frame; any other lettering, as the name
of the object or that of the producers of the negative and positive,
may be neatly written in with a chalk-pencil on the upper or lower bars.
The top and bottom bars can be removed and replaced with others
of different widths, so that the frame may be increased or decreased
in width at pleasure. This is likewise suspended from the rods R R,
and is so adjusted that the object is seen through it whilst the frame
itself occupies the margin of the picture. By this arrangement the
positive print gives a counterpart to which the type of the work it
illustrates refers, and at the same time gives a finished appearance to
the picture, whilst it also saves the expense and trouble of afterwards
engraving the references, &c. on the plate.

The Bark Room is separated from the light by black curtains C,
which can be drawn from each side towards the centre, by the par-
tition P, and a black blind B, which draws down, so that the room
may be made impervious to white light, when the picture is to be
made sensitive or developed. At other times the curtains and blinds
are drawn together so as to cut off the light which comes from beyond
the margin of the Indicating Frame. A window of glass, stained
yellow by oxide of silver, or common glass with two or three folds of
yellow glazed calico strained over it; or, according to Mr. Wilkinson’s
observations, a window may be made of sheet India rubber, about
1-32nd part of an inch in thickness, is placed at the side for observing
the development of the negative. The yellow media being employed
to cut off the actinic rays from the light admitted, which would other-
wise affect the sensitive plate. The sink is lined with gutta percha
and drains off into a carboy placed for the reception of the washings,
which contain silver, and are worthy of consideration in the econo-
mics of large photographie establishments ; the water being at
convenient opportunities evaporated off, the residue should be pre-
served, till a sufficient quantity is collected, to reduce the silver it
contains, or convert it into a useful salt.

The Camera, or dark chamber, is usually constructed of well
seasoned walnut-wood, in a manner similar to that figured above.

It consists of a base-board A (figs. 2, 3), 18 inches long, to the
under surface of which are screwed three brass plates BBB
(fig. 3): to these the spring legs, hereafter described, are attached.
To guard these plates and the clamp-serew J, a stout bead, about
14 inches deep, runs round the margin of the board, and is planed

7 SS

We |
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'D D
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so as to stand perfectly true on any level surface. To the base-
board is attached the front of the camera C: this is square and
63 inches long laterally, into this slides D, the telescopic part of
the back of the camera, which is 6 inches long. This should fit with
great accuracy, that it may move smoothly and not admit any
light into the interior. D’ is the part that receives the focussing
gla and plate-holders; laterally it is 44 inches long; in other
respects it corresponds with the dimensions of the front of the camera
C. The top of this portion, Z, is only about 33 inches wide, and is
moveable, sliding in two horizontal dovetail grooves in the sides of D’,
leaving an aperture for the reception of the plate-holders, either at
the back or towards the front of D’, according as to whether it is
pushed in the direction of the lens or drawn from it. ff are perpen-
dicular grooves in the sides of D’, into which the focussing- glass and
the plate-holders are accurately adjusted, so that the plates and the
ground glass may occupy exactly the same plane. By this arrange-
ment, together with the rackwork movement of the lens, a range of
foci, varying from 5 to 18 inches, are obtained. The replacement
of the ordinary trap by the sliding trap E, I have found advantageous.

In the front of C are two perpendicular dovetailed grooves, G G
(fig. 4), into which slides the board carrying the lens F, which
ean be fixed by means of the clamp-screw H, at varying heights.
This movement of the lens allows the image of the object to be
centered on the focussing glass without disturbing the parallelism
of the camera to the object itself, as otherwise it would be necessary
to resort to the objectionable mode of tilting the camera, to obtain
a proper distribution of fore ground. ‘The interior of the camera
is usually blackened, but M. Laucherer states, that by whitening it,
he has found the time of exposing the plate lessened, and that
there is greater uniformity in the distribution of the lights and

02

184 PRACTICAL APPLICATION OF PHOTOGRAPHY.

shades in the pictures obtained; but this method has been found
by others to be objectionable.

Fig. 4.

The Focussing Glass consists of a plate of ground glass’ fixed
into a frame of wood about 1 inch in thickness, in such a manner
that when the frame is dropped into the grooves ff, it shall exactly
coincide with the position the prepared surface will occupy in the
plate-holders when placed in the same grooves; in other words,
both focussing-glass and sensitive surface must be equally en
from the lens. The ground glass is ruled with squares and cireles
in pencil to correspond with the sizes and show the position the
various sized plate-holders occupy in the camera; and in focussing,
the image of the selected portion of the object is made to occupy
that sized circle which corresponds with the size of the plate on
which the picture is to be taken. When the focussing glass can be
used in the front grooves, the back part of D’ serves as a shade whilst
obtaining a sharp image of the object. In focussing, the rough
adjustment is obtained by means of the telescopic movement of the
camera ; the fine adjustment, by the rackwork or sliding moyement
of the lens.

After a satisfactory image is obtained, the back part of the camera

is clamped by means of the screw I, which runs in a slit in the base
board,

The Plate-holder consists of a wooden frame (fig. 5) K, about
1 inch thick, which exactly fills up the aperture that may be made
in either the back or front part of D’, and the grooves f f, into which
it slides. Into this frame may be fitted two glass-plates,* between
which sensitive paper is placed ; or these may be replaced by various

* This or any other glass that may be interposed between the light and
sensitive surface should be tested, according to Professor Stokes’s recent

experiments, to see if it be of a kind that will cut off the actinic rays of
the spectrum,

ENGRAVING, OR TAKING THE NEGATIVE. 185

plate-holders suited for the different sized plates. These are made
of oak slabs, of the thickness of the two glasses, having apertures
cut through them suited to the size of the plate they are intended
to hold, and of the shape shown in fig. 5. Across the angles
of these apertures are let four pieces of black glass, MM M M, of
the same thickness as one of the glass plates. On these corners is
dropped the prepared glass or metal plate, N: the sensitive surface

ur
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(

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i

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Fig. 5.

thus occupies the same plane as paper would between the glass
plates. A sectional view of glass and wood plate-holders is given
in fig. 5, the references being the same as in the back view. In
yertical side grooves, and in front of the holder and plate, works the
slide or shutter of the frame O: this is hinged, so that when it is
drawn up, it may be bent over the camera so as not to be in the way
whilst operating. A door hinged into the side of the frame, closes
in the plate; to the centre is screwed a spring, which presses the
plate up to the proper position when the door is closed and hasped.

Cameras are constructed in various ways, so as to render them
simpler and cheaper, or more complicated and costly, but the form
described is a very good type of what a working camera should be.
What are called hinged portable cameras are just costly refinements,
excepting where lenses of long focus or that cover a large field are
employed, for as a certain space must be occupied by the chemicals
and apparatus, &c. required for the various operations, this may just
as well be arranged for in the interior of the camera, which then
serves as a packing case, and is ready for use as soon as the box
containing the materials is removed from it. If the form of the
camera described is used for travelling, a handle should be let in
flush with the top of C (fig. 2).

Whe Lens.—Photographic lenses are of three kinds, the single—
the single combination—and the double combination,—which are
selected for use according to the nature of the object to be taken.

The desiderata in a lens are, sharpness of definition over the whole
of a flat field, depth of definition, coincidence of the plane of chemical
or actinie focus with that of the visual; in other words, the lens
should be free from spherical or (relatively) chromatic aberration—
I say relatively, for photographic lenses are not absolutely free from

186 PRACTICAL APPLICATION OF PHOTOGRAPHY.

chromatic aberration, for part of the thermotic and the actinic rays are
combined, those rays of the spectrum which produce the visual effect
being present in the focus and in the same plane with those which
combine to produce the aetinic effect, whilst lenses intended to be
used wiswally combine only those rays which have the greatest
intensity in producing light.

As the term “‘ achromatic,” in relation to the correction of photo-
graphic lenses, involves an erroneous idea, Mr. Hunt has lately
proposed the term ‘‘diactinie” for those bodies which are trans-
parent to the chemical rays, and ‘‘ adiactinic” for those which are
opaque to them.

Spherical aberration is attributable to the incident rays M
(fig. 6) not being equally refracted through different parts of the
lens, the rays nearest the axial ray being less refracted than those
nearer the marginal rays M, consequently they are collected at dif-
ferent foci, as is shown in fig. 6; the result being a confused image

Fig. 6.

of the object on the focussing glass, bright and sharp in the centre, but
gradually passing off into a hazy halo towards the edge. This is
dependent on the form of the lens—the greater its convexity, or the
greater the inequality of the curves on its two faces, with reference
to the direction of the incident rays, the greater will be the spherical
aberration: it is therefore less in a lens of periscopic form, which
renders the marginal rays longer than the axial rays when the concave
side is presented to the object.

Spherical aberration is still further corrected by placing a dia-
phragm, or stop, at such a distance before the lens that it will just
admit the rays of light from the object and thus exclude the margi-
nal rays, as in fig. 8. In proportion, however, as we decrease the
size of the aperture of the stop, we increase the sharpness of the
image and the size of the field, but the operation of exposing the
ensitive surface is prolonged in consequence of the amount of light

ENGRAVING, OR TAKING THE NEGATIVE. 187

thus cut off. This decrease of actinic power, by the use of stops, is
generally in the proportion of 1, 4, 8—thus, eeteris paribus, if with
the largest aperture a picture was given in one minute, the smaller
aperture would require four minutes, and the smallest eight minutes,
to produce the same effect.

Chromatic aberration is dependent on the unequal refrangibility
of each of the coloured rays into which white light is decomposed
whilst passing through the refracting substance of a lens.

As the red rays of the spectrum are least, whilst the violet rays
are most strongly refracted, it is evident that the violet or actinic
rays, A, will be collected at a shorter distance from the lens than
the red, or thermotic rays, 'T, as is shown in fig. 7. The space
between A and T constitutes the chromatic aberration, and within
it are situated, at various points, the intermediate rays of the spec-
trum. At the point of intersection of the violet and red rays is
situated the yellow or duminous rays and point of visual foci, L L.

If therefore we obtained a sharp image on a focussing glass placed
at LL, it would be necessary to place the sensitive surface, at A,
to obtain a photographic picture with an uncorrected lens: this dif-
ference between the chemical and visual foci, in a single crown
glass lens, usually amounts to about 1-27th of its focal length.

A simple mode of testing whether the visual and chemical foci
are coincident, or the amount of aberration between the two, so that,
in case of non-coincidence, the proper photogenic focus may be
indicated, is by placing the camera before a flight of miniature steps,
numbered on their faces from 1 to 7 consecutively, then focus for
number 4 the centre step, take a photograph of the steps; if 4
appears sharper than the other steps or numbers, the chemical and
visual foci coincide; on the other hand, if a number nearer to the
plate is most distinct, the chemical focus is shorter than the visual,
which indicates that the glass is under-corrected ; if a number further
from the plate is most distinct, the chemical focus is longer than the
visual, which indicates over-correction, and the photogenic focus
will then be behind instead of before the visual focus.

When lenses are used that have not these two foci coincident, a
scale indicating the variation between the chemical and visual foci
at different focal lengths should be marked on the draw-tube of the
lens or the telescopic part of the camera.

Ckromatic aberration is corrected in single lenses by the form of

188 PRACTICAL APPLICATION OF PHOTOGRAPHY.

the lens, the meniscus being the best, and by cutting off the mar-
ginal rays, in which chromatic aberration is chiefly resident, by
means of a ‘stop, S, as is shown in fig. 8.

Fig. 8.

The most effectual mode of correcting chromatic aberration is by
combining two lenses of media possessed of diferent refractive and
dispersive powers. This is usually effected by employing a double
convex lens of crown glass, the refractive power of which will place
the focus of the violet rays at v (fig. 9), and the red rays at r,
and a plano-concave or double concave of flint-glass, the refractive
power of which would place the violet rays in focus at 7’, and the
red rays at 2”, the result being the recombination of the various rays
into white light, and the production of an achromatic image at a
mean point dependent upon the focal lengths of the two lenses.

Fig. 9

The perfect correction of the chromatic aberration is solely de-
pendent on the proper ratio of the curves of the flint to the crown
glass lens, and, according to Mr. Ross’s experience, diactinism
can only be determined by trial with each individual lens.

The experiments of Professor Stokes, Malaguti, and Sir John Her-
schel, warn us that care should be taken in selecting for the con-
struction of photographic lenses such glass and cements as will not
impede the actinic rays.

A. refractive aberration is common to many lenses producing
images wherein straight lines are represented as bulged inwards or
outwards. ‘This defect is generally confounded with spherical aber-
ration: whereas it is depe sndent on the media of the lenses refract-
ing more strongly at the marginal than at the central part of the

ENGRAVING, OR TAKING THE NEGATIVE. 18¢

lens, consequently bending outwards those portions of a line which
are nearest the margin, and producing a pincushion shaped image of
a square, or zrwards producing a barrel shaped image of a square,
according to the form and position of the lens.

As the single lens is slower in action than the double combina-
tion, but as it gives a larger field and greater depth of definition
—by which term is meant the power of a lens to take in near and
distant objects with equal distinctness *—it is therefore best adapted
for landscapes and immoveable objects, as time, which is then of no
object, can be allowed for bringing out the detail of the picture.

Fig. 8 represents the section of a single lens or objective,
which is used on account of being cheaper, “and taking in a larger

field.

|

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Fig. 10.

Fig. 10 represents a single achromatic lens, in section, constructed
according to the principles of: correction described, with stops S ;
cap. O; and rackwork adjustment R.

With the double combination lens (fig. 11) two corrected lenses
are employed; and the aperture or diameter being greater in pro-

|

a eeeeseee SEA |

Fig. 11.

* The best instance I have seen of this is in Pretsch’s view of Vienna,
taken by a Ross’s lens, and exhibited at the late Photographic Exhibition
at the Society of Arts. On the front of a house, situated about fowr or six
miles distant from those in the foreground, the name of the occupant
is discernible.

182* PRACTICAL APPLICATION OF PHOTOGRAPHY.

portion to the focal length than in the single lens, it is more
intense and quicker in action, therefore best adapted for taking
portraits, pictures of animals, and other moving objects, though the
image is considerably reduced in size. The references S, QO, R in this
sectional diagram correspond with those in fig. 10,

Microscopic Objectives usually consist of three, sometimes only
two compound lenses ; but as they are over-corrected, the chemical

ISS

|
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Fig. 12.

aud visual foci do not coincide, therefore must be compensated for.
As it is important that the sensitive surface should be parallel to
the object-glass, and having found difficulty in centering the body of
the microscope to the camera, according to the mode recommended
by Mr. Delves and Mr. Shadbolt, I have adopted the arrangement
shown in fig. 12: a piece of tube is screwed into the flange of my
photographic lens, and into a plate with which one end is closed, is
screwed the object-glass; over this tube smoothly slides another,
likewise closed at one end, but having an aperture correspond-
ing to that of the lens: to this is attached a piece
of metal, on which slides the clamping slide-plate, re-
moved from the stand of my microscope ; or two springs
may be screwed to the front of the outer tube, the pur-
port of either being to hold the microscopical slide or
object. A scale, showing the difference between the
chemical and visual foci, should be marked on the inner
tube. With high powers a lever fine adjustment is neces-
sary. ‘To those photographers who have not microscopes,
this will be found an economical mode of adapting lenses
to their cameras, as the stand of the microscope is dis-
pensed with.

The Stand, in its simplest form, is made by fixing
three spring legs, of the construction shown in Fig. 13,
into the brass sockets B B B (Fig. 3), and thus forming
a steady tripod, which allows the Camera to be easily
adjusted in any position, and combines the advantage of
extreme portability. There are many other forms more
expensive or less portable, but which have advantages
under some circumstances. Amongst the latter is the
stereoscopic camera stand, which admits of that instru-
ment being fixed at different angles.

ENGRAVING, OR TAKING THE NEGATIVE. *1835

Arranging and Focussing the Object.—The proper position
of the object can only be learnt by experience, as it depends upon
an artistic appreciation of the arrangement of light and shade, com-
bined with a perfect knowledge of the chemical eftect of light when
radiated from surfaces of different colours. In anatomical subjects
flaccid muscle should be padded up with cotton wool into a natural
appearance of rotundity, the distinction between veins and arteries
being obtained by employing coloured injections possessed of dif-
ferent actinic actions ; and all parts that do not tend to a clear idea
of the object should be cleanly cut away. A dark drab cloth
should be thrown over the Object Table, to cover its mechanism,
and to form a background to the object. After the object has been
satisfactorily displayed, the indicating wires should then be adjusted
to any parts that are to be specially described. Skeletons may be
suspended from the rods R R (Fig. 1) by cords, or supports, of
the same colour as the background, to prevent their prominence in
the picture. Shadows of window bars, &c., must never fall across
the object. Living animals should be taken at favourable moments,
as when dozing in a standing posture, or on the look out for fuod ; if
wild, they should be induced to one end of a long, well-lighted
den, whilst the lens is inserted between the bars at the other.
Birds, reptiles, and some animals of a torpid nature, form very
favourable subjects for operating on. It should always be en-
deavoured to get all parts of the object in as nearly the same plane
as possible; if this cannot be attained, a small stop must be inserted
to obtain greater depth of definition with the lens, to prevent dis-
tortion of the natural proportions. The light should fall in parallel
rays on the object, and the Camera placed directly opposite it, and
in such a position that strong rays of light do not fall upon the lens
or intervene between it and the object. The lens should be adjusted
so as to be perfectly parallel with the object; and if this is near,
and inclines backwards from a plane vertical to the lens, a plate-
holder working onan axis may be adjusted to a position parallel with
the object.

A simple mode of ascertaining whether the Camera is level is by
placing a marble on its top; when level, of course the marble will
not roll in any direction; this likewise applies to the levelling
stands. When, by focussing, a sharp image of every part has been
obtained on the ground glass, the Camera is clamped, or, if working
with an uncorrected lens, the variation between the two foci must
first be allowed for. If a stereoscopic view of the object is to be
taken, the Camera may be moved round about six degrees, to one side
of a line central with the subject, anda particular part focussed on a
fixed spot of the ground glass; the camera is then moved round to
a corresponding degree on the other side of the central line, the
same distance from the object being preserved, and the same part
again focussed on the same spot. The two Photographs, taken at
different points of view, when viewed in juxtaposition stereo-
scopically, resolve themselves into one image, with an appearance
of solidity and elevation.

+

184* PRACTICAL APPLICATION OF PHOTOGRAPHY.

With microscopic objects beautiful effects of light and shade may
be produced by the employment of polarized light, as the varying
thiekness of the object (as in crystals of urinary salts, &c.) produces
colours of different actinic action; and with a Darker’s selenite
stage great command may be obtained over the colours desirable
for producing the best effects by this mode of arrangement.

Cleaning the Plates.—Perfect cleanliness being of the wtmost
importance, when the plates are first received from the glass
warehouse they should be immersed in a bath of liquor ammonia
and water in equal parts, that all traces of grease may be removed,
or, if they have been previously used with iron developing solutions,
they should be treated with a bath of two parts nitric acid to one of
water, and afterwards thorowgh/y rinsed with pure water. A con-
venient form of trough for these cleansing operations may be made
of gutta percha, the sides being grooved for the reception of each
plate separately, so that the liquid may have free access to both
surfaces of the plate. To suit plates of different sizes, a moveable
grooved slab may be fitted to move across the centre of the trough,
so as to advance or recede according to the width of the plates ;
as soap contains grease it should never be employed. On remov-
ing the plates from the water they are wiped with a perfectly clean
linen cloth, then laid on a flat metal plate,* and polished off with a
silk handkerchief, a circular motion of the hand being used: they
are then put away in the stock box till required. Before coating
the plate with collodion it should be finally polished by rubbing it
on a doe-skin buff, about ten inches long by four wide, and then
dropped into a wooden bowl, to prevent contact with any unclean
surface. To preserve the buff from dust it should have a hinged
cover, only to be kept open during the operation of polishing.
The moment before applying the collodion the surface of the plate
should be lightly wiped with a cambric handkerchief to remove any
trace of dust. :

Glass Plates.—The glass plates on which the negatives are
taken should be of the best patent plate, about } inch thick, per-
fectly free from any irregularity of surface, and cut to fit the pres-
sure-frames best suited to the size of the page to be illustrated, and
the edges then ground.

Kodized Collodion is a preparation of gun-cotton dissolved in
a mixture of anhydrous ether and alcohol, and iodized with pure
and white iodide of ammonium, or what is better, as it keeps longer
and is more conveniently applied, the iodide of silver and ammonium.
By varying the proportion of the alcohol this may be made to
produce films of different thicknesses and degrees of tenacity. The
greater the quantity the quicker and more even is its action; but,
if too much is added, it becomes attenuated, and then cracks and
parts from the plate. If the film is to be transferred to paper,

* The metallic surface prevents the accumulation of any electricity pro-
duced by the friction of the silk, which otherwise would attract floating
particles of dust.

o

ENGRAVING, OR TAKING THE NEGATIVE. *185

blocks or plates, it must be of a very stout quality. The neck of
the bottle containing the collodion must always be freed from deposit
before pouring any out.

Coating the Plate.—Bend the forefinger of the left hand into
an angle, with the tip pressing on the ball of the thumb; on this
rest the corner of the glass plate numbered 1 in the annexed figure,
and hold it firmly with the end of the thumb ;
breathe on the glass to see if it is sufficiently |?
clean and dry; if so, the vapour will pass off
instantly ; give it the final wipe with the cambric 1 4
handkerchief, then bringing the glass into a =~
horizontal position, pour the collodion plentifully on to the centre
of the plate; incline the plate so that it will flow smoothly and
gently into the corner marked 1, avoiding the thumb, then into 2,
then 3, and lastly 4 (if the film appears too thin, it may be again
flushed up to 2, allowed to spread over the plate, and again returned
to 4), when, without touching the neck, return the superfluous
collodion to the bottle, bring the plate into a vertical position,
and impart a tremulous motion to the plate along the direction of
its longer axis, so that the ridges formed by draining may run into
one another: pass the lip of the bottle along the edge from 1 to 4
and from 4 to 8, backwards and forwards several times till all
superfluous liquid is drained off: the result should be a perfectly
smooth and even film. When the collodion is sufficiently set, and
which can only be judged of from experience, it is ready for exciting.

3

The Sensitive Bath.—A gutta percha trough | inch across,
and about the dimensions of the largest plate of your camera, is
usually used for the sensitive solution, and should be fixed obliqaely
on a block of wood, not perpendicularly as is generally the case, for
this position facilitates the insertion and management of the plate.
I, however, prefer the glass trough adapted to the camera, which
holds the bath,in a position coincident with the focussing glass, as
this arrangement certainly facilitates and shortens the operation.
In either case a glass dipper may be used, which is simply a strip
of glass with another piece cemented across it, on which the plate
rests.

The trough is charged nearly full with a bath, which may be
prepared according to Mr. Hennah’s formula, in the following pro-
portions :—

Nitrate of silver . : . 40 grains.
Distilled water. : . lL ounce.
Alcohol . : : . 25 minims.

Separate about an eighth of the quantity prepared, and to the greater
bulk add, drop by drop, a solution of iodide of potassium till a preci-
pitate of iodide of silver is formed ; agitate, and allow it to stand for
some hours till the precipitate is dissolved ; filter, and then add the
portion previously set aside ; test with litmus paper, and if the bath is
neutral add nitric acid, in the proportion of two drops to the pint—

186* PRACTICAL APPLICATION OF PHOTOGRAPHY,

prepare rather more of this solution than is absolutely required to
fill the trough. When by use this bath is robbed of its proper pro-
portion of nitrate of silver, it may be again restored to its former
strength by the judicious addition of a saturated solution of that
salt. When not in use, it should be kept in a bottle; if in use, a
lid fitted into the mouth of the trough, or the bath-frame of the
camera, will preserve it from dust. When the temperature is below
60° Fabr. the bath should be raised to this point by placing it in a
water-bath or by warming the room. The operating room, during
the process of exciting the collodion film, must be preserved from
the admission of white light, and yellow light only employed.
The coated plate is rested on the dipper, previously moistened to
promote adhesion, and with one steady plunge is passed into the
bath. If there is the slightest pause, a line will be produced across
the film, which will be imparted to the posztves printed from it.
After remaining in the bath for about a minute it is lifted in and out
two or three times, and when the liquid flows evenly over the film it
is sufficiently saturated ; it is then drained, the uncoated side laid ona
pad of blotting-paper to remove superfluous moisture, and finally
adjusted in the plateholder, with pieces of blotting-paper interposed
between the corners of the plates and the glass rests (M, M, M, M,
fiz. 5). If the glass bath adjusted to the camera is employed, the
plate may be coated in the open air; and when the collodion is in a
proper condition, the plate, resting against the sloping back of the
bath, is plunged in, and the lid of the bath-frame shut down: in
two minutes raise the lid and push the plate up to the front glass of
the trough, so that it occupies a position corresponding with the
plane of the focussing glass, and again close the lid, taking care
during this movement not to allow any light to fall into the bath,
which may be obviated by throwing a black cloth or yellow hand-
kerchief* over this end of the camera.

Exposing the Plate.—If operating in the rooms described,
pull up to the required height the blind that shuts off the light
from the room containing the object, and see that there is a sharp
image on the focussing glass ; then fit the cap on to the lens, replace
the focussing glass with the plateholder or bath-frame, raise the
shutter of the frame (QO, fig. 5), remove the cap of the lens and
expose for the necessary time, replace the cap, close the shutter,
remove the frame, and proceed to develop the picture as soon as
possible. The requisite time for exposure can only be judged of by
experience, as it depends upon a knowledge of the action of the
lens employed, whether single or double combination, the size of
the stop, the sensitiveness or age of the collodion, and the nature
of the light, colour of the object, and the temperature of the atmo-
sphere at the time of operating; but it varies from a moment to a
quarter of an hour. With asingle achromatic lens, of 12 inches

_A large pw pocket-handkerchief will be found a very useful com-
panion to a photographer when on a tour,

ENGRAVING, OR ‘TAKING THE NEGATIVE. F187

focal length, 3 inches diameter, and 4 inch stop, from 10 to 30
seconds will be, however, on an average, found sufficient. If a
negative is required, it must be exposed longer than for a positive.

Developing the Negative.—On removing the plate in the
darkened room no picture will be visible; if it has been exposed
long enough for the production of a negative, develop the latent
image with the following solution :—

Distilled water 5 a . 8 ounces.
Glacial acetic acid . ; . 14 drams.
Pyro-gallic acid. : . 12 grains.

If there is any sediment after the pyro-gallic acid has dissolved,
filter and preserve it in a bottle. Place the plate on a stand,
having an arrangement of screws by which it may be brought to a
level; or the plan I employ saves the expense of this stand—across
a glass plate, about 6 inches by 4, I cement a thicker strip about
13 inch from one end, to prevent the liquid flowing up to the
fingers and staining them; round the longer end I fold a piece of
stout blotting-paper like a note; when this is moistened it acts as a
sucker when the plate is laid on it, and may be moved about by the
hand without fear of its separating. Having, by either of these
means, brought the plate to a horizontal position, pour out, into a
perfectly clean glass measure, a quantity of the developing solution
sufficient for the size of the plate, and for every dram add 2 drops
of a solution of nitrate of silver in the proportion of 40 grains to
1 ounce of distilled water.

A plate 4 inches by 3 requires 2 drams.
5 +

2? o 9 9 29

9 oe ” ~ ” 7 22
29 8&3 2? 63 >? 12

Pour this over the surface, and if the plate is held on the sucker
impart a gentle whirling motion to it, that a perfect dispersion of the
liquid may be facilitated. The lights of the picture should appear
first, and then the shadows, according to their depth of tone.
Examine the progress of the development by reflected light, and
when the details of the original are well defined pour off the liquid,
and wash in the horizontal position with a stream of cistern water
poured gently over its surface. Never retain the solution on the
plate after it has attained a dark brown colour; and if the plate has
been under exposed, which may be known by the picture appearing
very slowly, and by the lights deepening before the appearance of
the shades, it should be washed off before the whites become opaque.
If, on the other hand, both lights and shades appear instantly and
about the same moment, with little difference of tint, the plate has
been over exposed, and little can be done to make it useful.

Developing the Positive.—If a positive is required, the pic-
ture should have a shorter exposure in the camera, and be developed

190 PRACTICAL APPLICATION OF PHOTOGRAPHY.

with the previous solution, to which a few drops of nitric acid has
been added.*

Fixing the Piecture.—Cover the surface of the plate with a
saturated solution of hyposulphite of soda, and by daylight watch
the absorption of the iodide of silver, when every trace of this
yellow salt has been dissolved, well wash it, and leave a body of
water on the surface of the plate for twenty minutes, maintaining
it in a horizontal position throughout this operation.| After the
plate has been washed several times (for it is important that every trace
of the hyposulphite of soda be removed, or it will crystallize and spoil
the negative, as it would fade during the exposure when printing from
it), it is drained, and, when perfectly dry, varnished with amber dis-
solved in chloroform, which is applied ina similar manner to coating
the plate with collodion ; the negative is then ready to print from.

MAKING THE PLATES READY FOR PRINTING.

For printing, negative plates are alone employed. ‘The side
coated with collodion is laid on the albuminized surface of the
positive paper, pressure employed to bring them into close contact,
and they are then exposed to the light till the proper depth of
colour is obtained. The best form of pressure-frame is that sold
by Newman, of Regent Street, as the pressure is very equally dis-
tributed over the surface, so that there is little danger of breaking
the glasses, and is thus constructed. A very flat, strong, well-
seasoned board, with a cushion of cotton-velvet, padded with layers
of flannel, is attached to two strong bars, which again fit into a still
stronger bar, as will be readily
understood by consulting the back
and lateral views (Fig. 14). This
cross-bar carries a screw at each
end, over which a frame, fitted
with a plate of glass, about 3-8ths
of an inch thick, and correspond-
ing with the size of the cushioned
board, drops, and which can be
screwed down to any required
pressure by means of the nuts fit-
ting on to the screws.

In the ordinary way each sub-
ject is printed on paper, only a
little larger than tie size of the
picture ; afterwards trimmed and
mounted on paper ; but in the pre-
sent instance it will be perceived
. that both views, together with the
Fig 14. letterings, are printed on one sheet
and by a single operation.

* See also Mr. Shadbolt’s Paper, Micro. Jour., p. 169.

{ A levelling stand may be readily formed of a gallipot and wedge of
cork, placed in a dish or tray.

ENGRAVING, OR TAKING THE NEGATIVE. 189

For the purpose of saving time (an important point in the appli-
eation of photography to the illustration of periodicals or other
works) I found it necessary to contrive a special arrangement to
attain this end; and experience gained in working this out on the
photographs illustrating this Journal fully justities the adoption
of this method for the future. In a stout board, 3-inch thick,
square apertures, in proportion to the size of the page to be illus-
trated, are cut, just deep enough to admit a piece of plate-glass,
t-inch thick, and the negative plate, so that when they are inserted
together, the glass is flush with the wood; the thick plate, which is
placed undermost, is rather larger than the negative, to allow of
two beads fixing it down to the rabbet on which it rests ; within the
beads the negative plate is cemented by its edges, collodion film
uppermost. Above this is cemented the lettering-piece, which
consists of a strip of glass, coated and blackened by the albumen or
collodion process, and then engraved backwards and varnished ;
this arrangement will be understood by examining Fig. 14.

If the negative plates are too large for the work they are intended
to illustrate, as was the case in the present instance, being about 6
inches by 5, the best portion must be selected, the centre of this
ascertained, and a circle scratched round it with the sharp point of the
compasses; the plate is then cut down witha diamond to the proper
sized square. If the object would appear to. best effect with a black
border, as in the figure of the Trachee of the Silkworm, the collodion
film must be carefully trimmed away with a graver from the margin
of the circle, then cleaned off with a cloth moistened with spirit, so
as to leave the margin perfectly clear for the passage of light ; this
consequently prints black ; on the other hand, when the subject is
dark, as the Proboscis of the Fly, and would be thrown up with the
contrast of a white ground, a circle must be cut out of black glazed
paper, the aperture adjusted to the circle containing the part
eee and the margin gummed down to the collodion side of the
plate,

Here I would suggest that if photography is found advantageous
for the illustration of microscopical works, authors should adopt a
plan similar to that found so convenient with object slides, of using
a fixed scale of sizes for their glass plates, which must be determined
by the sizes of the books they are intended to illustrate. A demy-
octavo, with two negatives io the page, will only allow of the plates
being 4 inches square ; a demy-quarto will take in four of these

plates, or two plates 5 inches square ; a square octavo, one of the
latter size.

As by this arrangement of the pressure-frame, both the objects
and lettering-pieces are printed on the same sheet of paper at the
same moment, labour and time, which otherwise would be neces-
sarily employed in mounting them, are saved, consequently expense.

VOL, I, G.*

190 PRACTICAL APPLICATION OF PHOTOGRAPHY.

PRINTING THE POSITIVE.
ALBUMINIZED PAPER PROCEss.

The Positives, with which the present Number of this Journal is
illustrated, are obtained by the albuminized paper process, which
has been selected on account of the brillianey of the lights, inten-
sity of the shadows, and definition of the pictures it produces.

Whe Paper should have a smooth surface, a firm and even"
texture, weight from 12 to 24 Ibs. per ream, of equal transparency |
throughout, free from spots of any kind ; not too strongly sized,—a
starch-sized being preferable to a gelatine-sized paper; as chemi-
cally pure as possible, free from watermark, and old paper should
be selected in preference to new—the best papers for photographic
purposes being those manufactured by Canson Freres, Turner,
Whatman, and Lacroix.

The quality of a paper is ascertained by examining it vertically
before a light, and the side to be chosen is that which does not show
any small square indentations: this, being the smoothest of the two
surfaces, is selected, and, for future recognition, should be marked
in pencil with the letter R.

For the albuminized process Canson Freres’ thick paper will be
found the best, which should be cut in sizes, about 4 inch longer
than the length of the picture required.

The Albumen, Jn a large-lipped basin mix the following pro-
portions :—

The white ofeggs - - - - - = = loz*
Distilled water - = ~ - == - - loz.
Chloride of sodium - ae (sb de Se cee ee } OZ.

Whisk this mixture up to a white froth with a wooden or ivory salad-
fork, or, what is better, a bundle of three or four pens stripped of
the feathers ; then skim with a wooden or ivory spoon, cover it with
a glass plate, and let it stand for twenty-four hours. The scum
that is formed on the surface at the end of that time should not be
removed, as it protects the rest from dust. Make a small hole in
this scum near the lip of the basin, and gently decant a sufficient
quantity to cover the bottom of a gutta percha trough to the depth
of ¢inch. The best troughs that I have seen are those sold by
Henneman ; they are stamped in moulds, and are attached to slabs
formed out of two pieces of well seasoned wood glued together in
reverse positions of the grain: this effectually prevents warping,
and secures a very flat bottom. As the internal surface is polished,
it should never be wiped out with anything but a piece of fine sponge,
and when not in use should be kept filled with water. Remove any
air-bubbles that may form on the albumen with a piece of paper,
then take the paper by two corners diagonally opposite, between the
tips of the fingers and thumbs ; lay one corner on the albumen, bend

* One ounce equals the white of one egg.

PRINTING THE POSITIVE. 191

the paper backwards till it bulges out like a ‘ squaresail ” before the
wind, lower the edge nearest the body gently on to the surface, and
then, with an eyen and sweeping motion of the hand, carry forward
the marked side of the paper over the surface of the albumen till it
floats flat thereon, taking great precautions that air-bubbles are not
interposed, and that the paper never touches the bottom of the
trough, as in either case it would be spoilt ; allow the paper to rest
for two or three minutes, then with a reverse motion of the hand
rip it off the albumen, allow it to drain from a corner, pin it by one
corner on to a tape stretched across the room; in a few minutes
make a small piece of blotting-paper adhere to the lowest corner to
absorb all moisture that may drain into it; when dry, place it on
three or four sheets of blotting-paper, and one sheet on the back ;
then p ss an iron over it so warm that saliva just simmers onit. ‘This
coagulates the albumen, forming an insoluble size which renders the
paper very tough.

Making the Paper Sensitive.—In the dark room is placed a
gutta percha trough, containing a solution* of—

Nitrate of silver - - - - - = - 120 grains.
misled water = ~- 9 ' =. = =e = = TL 08.
on which the albuminized paper is floated for two or three minutes,
and then dried in the same way and with the same precautions as in
the former operations. When dry, the papers curl up into cones,
like grocers’ sugar papers, and in a similar manner may be packed
one inside the other, and placed in a tin case till required for use.

If protected from white light, this paper will keep for about a
week after its preparation.

Exposing in the Pressure-frame.—In the darkened room
take the sensitive albuminized paper, spread it out flat, and adjust
it on the cushion of the pressure-frame ; place the board into which
the negatives are fixed over it, so that the coated surface of the
plates is in contact with the sensitive side of the paper; screw the
two boards tight together, tilt the frame over into such a position
that an equal beam of light falls upon the picture ; if in the direct
rays of the sun, expose for about three minutes ; if in diffused light,
from half an hour to one hour. The exact time for obtaining the
tone required can, however, only be judged of by experience, as
the depth of tone of the negatives operated with, and the amount
and kind of light during the time of printing, must be taken into
consideration. It is, however, better to over than under-print the
positives, as the tone can always be reduced, but not increased, by
after cperations.

Fixing.—The positives must be finally fixed by carefully dis-
solving out all the remaining chloride of silver they contain by

* This proportion may be considered extremely strong, but Mr. Henne-
man finds that it produces vigorous pictures with rapidity. The silver may
be reduced to 100, 80, 50 grains, or less, but the chloride of sodium must
be reduced in proportion,

Oo” 2

192 PRACTICAL APPLICATION OF PHOTOGRAPHY.

immersing them in a bath of one part of a saturated solution of
hyposulphite of soda and eight parts of water. The older this bath
becomes the better are the tones obtained ; care being taken to add
occasionally some fresh crystals of the hyposulphite to prevent its
being saturated with the salt of silver obtained from the positive
previously treated in it, in which case its dissolving powers cease.
Fixing and Toning.— Various tones, from India paper tints to
pure black, may be given to the positives thus obtained, by treating
them, after removal from the pressure-frame, with a bath of—

Hyposulphite of soda..- -... =» -s }=5. =.00e@
Water .= > =. -» -iws0 5s ae eee
Chloride ofgold - - - - - = = 2 grains,

contained in a gutta percha trough, the positive being placed with
the picture uppermost. By this method the positive is toned and
fixed by the same operation. .

Watch the proof till the desired tone has been obtained, the posi-
tives should then be removed, and afterwards washed ina succession
of baths of warm water till every trace of hyposulphite of soda is
removed. These washings usually require about six baths of a
quarter of an hour each, and then a final one in distilled water. Too
great care cannot be devoted to this operation being thoroughly
performed, as otherwise the pictures fade in the course of time.

On removal from the last bath dry the proofs by suspension ;
when dry, smooth them out by passing a warm iron over the backs,
or hot-press them ; the warnith also improves the tones of the picture,
and glazes it. ;

Having placed before the reader the various stages of the col-
lodion and albumen process, it will be readily understood what
advantages the former offers, for whilst by its aid we can obtain
faithful delineations of such an object as the Proboscis of the Fly,
from the moment of coating the plate to its final varnishing, in less
than a quarter of an hour, and at the cost of a few pence, the same
subject engraved on wood, with an equal amount of minuteness,
would occupy a wood-engraver a month, and at a cost of not less
than ten pounds. On the other hand, the expense of the employ-
ment of silver salts, and the time required in fixing the positives,
cousiderably enhances the cost of printing from them. 1 trust, how-
ever, that photographers will see the necessity of devoting their
attention to the perfection of some printing process wherein cheaper
sensitive materials can be employed, and probably some of the
chromates. would supply this desideratum: but such rapid and
vigorous results have been obtained by the employment of the silver
salts, that there has been little inducement to seek perfection by aid
of other, though cheaper, agents. As yet the economies of the art
have not come fairly before them.

Another cause, tending to make Photographic Printing expensive
and inconvenient, is the entire dependence of the operator on fa-
vourable weather; means should, therefore, be adopted to render

PRINTING THE POSITIVE. 193

him independent of natural light, and little difficulty would, I
think, be experienced in arranging a diffused artificial light suitable
for photographic purposes ; and the aim should be to produce a
bluish violet-coloured flame, not an intensely white or yellow one.
It will be seen that the photographer occupies the position of the
draftsman, engraver, and printer of ordinary processes; but the
analogues of drawing and engraving being performed at one and the
same moment suggests a division of labour between the Photo-
graphic Artist, who would devote his attention to the artistic prin-
ciples of the subject and the production of the negatives, and the
Photographic Printer, who would conduct the processes for the pro-
duction of positives; and this branch should be conducted on an
extensive scale, with division of labour, but this not of an expensive
kind, as children or girls might be employed with advantage ; and,
as mechanical means generally facilitate labour, a photographic
press, of the following construction, might be employed. <A flat

board, with beaded edges, carries two upright supports for the axis
of a glass cylinder, covered with a few layers of cloth ; this is kept
saturated with the sensitive solution by a reservoir attached to one
of the uprights, the bottom of which is prolonged into a tube drilled
with a row of holes, from which the liquid flows on to the cylinder
according to the amount of atmospheric pressure exerted on its sur-
face, which is governed by the admission of air into the reservoir, by
means of a stop-cock attached to its neck. The paper is laid on a
cushion, sliding between the beads of the base board, and a silver
plate, with apertures corresponding to the size of the surface to be
made sensitive, is brought down on it ; it is then passed under the cy-
linder, which has previously been regulated to the proper amount of
pressure, by screws affecting the springs on which its axis rests, the
paper is then removed, and that part only which is to be acted on
will have been made sensitive instead of the whole of its surface,
thus preventing the absorption of more liquid than is necessary.

In many instances collodion films may, with advantage, be
transferred to wood, metal, or stone, and thus save the drafts-

194 PRINTING THE POSITIVE.

man’s labours altogether. When metal plates, however, are to be
engraved from photographs, the employment of the daguerreotype
process would be more advantageous, the practicability of which
has already been demonstrated in Donné and Foucault’s ‘‘ Cours de
Microscopie complémentaire des Etudes Médicales,” published as
early as 1846. ,

In concluding this article, I beg to offer my sincere obligations
to Mr. Delves for his liberal and valuable aid in furnishing, for
this Number of the ‘ Microscopical Journal,’ the requisite number
of negatives from which the positive proofs were produced by
Mr. Henneman of Regent Street; also to Mr. A. Ross and Mr.
Henneman, for their kindness and readiness in affording me infor-
mation on lenses and practical photography. And if, in describing the
various operations, I have risked appearing diffuse, it is because I am
convinced that success in these processes depends upon the minutiz
and niceties of the manipulations, but which, however difficult they
may appear in type to the uninitiated, after a few trials will come
readily to hand, and, with moderate attention, will be rewarded with
success,

( 195)

TRANSLATIONS.

On Unicettutar Piants and Awnimats. By C. Tu. v.
Siebold. From Siebold and KoOlliker’s Zeitsch., f. w.
Zool. Bad. 1, p. 270.

(Continued from page 121.)

Respecting the motions, which have been frequently noticed
in unicellular Algw, Niageli observes very truly (p. 19), that
they present nothing of a spontaneous or animal character,
since they arise, not in the contraction or expansion of the
membrane, excited by an external or internal irritant, but
proceed singly from the vegetative processes of absorption
and excretion of fluid, and the formation and solution of solid
matters. Of the four categories of these plant-motions dis-
tinguished by Nigeli, we are here interested only in the third
and fourth, since it is precisely those which have been con-
founded with animal movements.

The slow forward and backward movement, which has been
observed in several Diatomacez and Desmidiacee, is explained
by Nageli (p. 20) in the following satisfactory way :—‘ The
cells have no special organs for these movements. But as, in
consequence of their nutritive processes, they take it and give
out fluid matters, the cells necessarily move, when the attrac-
tion and the emission of the fluids is unequally distributed on
parts of the surface, and is so active as to overcome the re-
sistance of the water. This motion, consequently, is observed
more particularly in those cells which, in consequence of their
taper forms, easily pass through the water ; these cells, more-
over, move only in the direction of their long axis. If one
half of a spindle-shaped or ellipsoidal cell chiefly or ex-
clusively admits material, the other half, on the contrary,
giving it out, the cell moves towards the side where the ad-
mission takes place. But as in these cells both halves are
physiologically and morphologically exactly alike, so it is that
it is first the one and then the other half which admits or
emits, and, consequently, the cell moves sometimes in one,
sometimes in the opposite direction.”

In this way may be explained, perhaps, all those motions,
which are so readily noticed in the Bacillaria. Only a com-
plete misconception of these plant-motions could have induced
Ehrenberg to seek for motile organs in these organisms.
According to him, it would appear, for instance, that the

196 SIEBOLD ON UNICELLULAR PLANTS AND ANIMALS,

Navicularia can project an undivided motile organ like the
foot of a snail from one of the central openings of the shield.
This pedal organ is said to lie constantly closely applied to
the shield, but to admit of its being extended as far as the two
extremities. I have never been able to detect this organ in
any Navicula, nor has Kiitzing, with his utmost endeavours,
succeeded in the finding of it. As, on the other hand, Schmidt
and Eckhardt (Wiegmann’s Archiv, 1846, Bd. I. p. 212) have
been more successful and have seen this remarkable foot, I
can only oppose to this the following observations. Ehrenberg
states, that in Navicula there are six rounded openings upon
the dorsal and abdominal surfaces—four at each end and two
in the middle. Of the four openings at the ends, the two on
the abdominal surface are said to be oral openings, and the
two on the dorsal, respiratory, whilst the central opening of
the abdominal surface is stated to be for the protrusion of the
foot. In Navicula fulwa Ehrenberg supposes that a similar
foot-like organ is protruded also from the dorsal opening.
How Ehrenberg has been thus deceived I know not, but in
contradiction to all these various erroneous notions, I can only
say this much, that these six openings in Navicula have no
existence whatever, but that precisely in the spots at which
Ehrenberg and others suppose they have seen six openings,
the siliceous cell-membrane is thickened and consequently
forms so many rounded eminences which project internally.
It is, therefore, needless to say, that there can no longer be any
question about either oral or respiratory openings, nor of
openings for the passage of a motile organ. On the same two
surfaces, upon which the six round thickenings of the siliceous
shield of Navicula are placed, there are observable, on the
contrary, four lines, running along the middle of the surfaces
from one thickening to the other. These lines, which have
been long known, but hitherto apparently but little noticed,
are to be referred to a suture, fissure, or rather gap, in which
no siliceous matter is deposited, so that in these places the
delicate primordial membrane which lines the siliceous shield
can be brought in close relation with the external world.
I come to this conclusion from the circumstance that it is
exactly at these four sutures or fissures that the water sur-
rounding the Navicula is set'in motion. The existence of this
current is readily demonstrated if some minute solid particles
are added to the water in which are some fresh Navicule.
Indigo is the best for this purpose. When water thus coloured
with indigo has come to a state of rest on the object-glass, it
will soon be perceived by the microscope that those particles
of indigo which come in contract with the living Navicule

SIEBOLD ON UNICELLULAR PLANTS AND ANIMALS, 197

are set into a quivering motion, although previously quite
motionless. It will, moreover, be perceived that only that
indigo is set in motion which is in contact with the four
above-described sutures of the siliceous shield, whilst the
particles of indigo adherent to the other parts of the shield re-
main altogether motionless. Besides the quivering movement,
another very striking motion is perceptible in these indigo
particles, which, when they come in contact with the sutures
of the silaceous shield, are forced pretty rapidly up and down
upon it. The indigo ‘particles, which are propelled from the
terminal towards the two central eminences, are never observed
to pass beyond the latter; at this point there is always a quiet
space, from which the particles of indigo are again repelled in
a reverse direction towards the extremities. This proves that
the linear sutures, as may in fact be seen, do not extend over
the central eminences of the shield. The current at these
clefts is occasionally so strong that proportionally large bodies
are set in motion by it.*

These movements did not escape Ehrenberg, when he
endeavoured to feed the Naviculacee with indigo, although
he explained them erroneously, attributing the attraction and
repulsion of neighbouring substances, in the case of Navicule,
to the pedal motile organ. Moreover, that Ehrenberg had not
apprehended these movements with full attention, is evident
from the figures above cited, in which he indicates that the
indigo on both surfaces of a Navicula viridis passes beyond
the central eminence. It is to be regretted that Nageli, in the
paper here quoted, has not subjected the Diatomacee to any
special investigation, from which we should undoubtedly have
gained much information respecting these unicellular or-
ganisms.

The fourth sort of movement noticed by Nageli (p. 20) in the
unicellular Algz is of most especial interest, viz. the “ Swarm-
ing,” which occurs in many Palmellacezw, Protococcacee, and
Vaucheriacee. He remarks very correctly that this ‘“‘ Swarm-

* JT will take this opportunity to remark that water coloured with indigo
is an excellent means for the study of the remarkable plant motions of the
Oscillatoria, which have heretofore been regarded as of an animal nature
by various naturalists. These plants afford a very interesting sight when
thus examined. The particles of indigo which come in contact with the
single filaments of the Oscillatoria are propelled in a tolerably close spiral
along the filament to its extremity. Whether the filament itself continues
to move or is quiescent, it was equally striking to me to notice that occa-
sionally this spirally gliding motion of the indigo took place from each
end of a filament towards the middle, in cases where the colouring matter
was agglomerated into a ball, or that this motion sometimes proceeded in
a reverse direction from the middle of a filament towards each end.

VOL. I. P

198 SIEBOLD ON UNICELLULAR PLANTS AND ANIMALS.

ing” is a phenomenon identical with that observable in the spo~
rangia of the multicellular Algae (U/othrix, Conferva, Cheto-
phora, &c.). I must here, in passing, remark, that Nageli,
Thuret, &c., when speaking of “ Swarm-spores,” do not thereby
understand any sort of moving corpuscles accidentally met with
in the water, and arbitrarily taken for vegetable forms, just as
similar corpuscles in the water have been arbitrarily considered
as animals by Ehrenberg. ‘These naturalists have rather ob-
served the development of these Swarm-cells or spores within
their mother-cells, in uni- or multi-cellular Algz, and have dis-
tinctly satisfied themselves of the vegetable origin of these
free-swimming corpuscles, In this way it was not left to the
subjective judgment of the observer to decide, according to the
impression he might receive, whether these corpuscles are
plants or animals. Ehrenberg, therefore, is in error when he
pronounces the Swarm-spores of Algz, the development of
which he has not observed, to be Infusoria; and Thuret is in
no way to be blamed, as he is by Eckhardt (op. c., p. 214),
in his figuring moving bodies (supposed Infusoria), which,
however, he saw developed in the cells of Algz, and escaping
therefrom, as spores of Alge.

Nageli (p. 20) thus expresses himself with respect to the
Swarming of unicellular Alga:—‘ It is usually the solitary
individuals that swarm, rarely the families consisting of several
individuals. ‘The swarm-cells have,.for the most part, an
ovoid or short pyriform, rarely a spherical figure; they have
at the narrower colourless extremity two or four, or a circlet
of very delicate cilia, or are covered throughout with similar
cilia. Under the microscope the motion appears very rapid,
somewhat of an infusorial character, consisting in a conti-
nual progression, in which the hyaline, narrower extremity is
usually in front, and the cell is continually turning on its long
axis. Although the swarming bears a resemblance to the
motion of Infusoria, it is clearly wanting in the spontaneity of
the latter. The Infusoria advance, spring back, turn round,
return, all spontaneously ; the swarm-spores pursue (p. 21)
a uniform and, for the most part, pretty straight course, de-
viating from it, or turning round only upon meeting an ob-
stacle, impinging upon which they are diverted into another
direction. Besides this, the wall of the swarm-cell, although
extremely delicate, is yet impassive and motionless, whilst in
the Infusoria, either the membrane is manifestly contractile,
or its appendages (cilia) are motile.”

I entirely agree in this representation and explanation of the
“swarming in the unicellular Algae, which is also entirely in
accordance with what takes place in the multicellular Alga,

SIEBOLD ON UNICELLULAR PLANTS AND ANIMALS. 199

and have already so expressed myself (De finib. inter regnum
animale et vegetabile constituendis. Erlange: 1843). Only
I cannot concur with Nageli when he makes a difference be-
tween vegetable and animal cilia, saying that the former, the
delicate plant cilia, are rigid, or admit of only passive
movements, whilst the animal cilia alone are said to possess
the faculty of spontaneous motility. To this Nageli adds
(p. 22), that although it is true the cilia do move in otherwise
entirely rigid swarm-spores, yet he denies that they are the
cause of the motion of the swarm-cells, because there vibra-
tion is only the natural consequence of the current in the water
produced by the active endosmosis and exosmosis of the cells.
According to Nageli absorption, is effected at the hyaline ex-
tremity corresponding to the root end of a plant, by which is
explained the fact that the swarm-spore swims with that end
in front, attraction being set up at that extremity, and repul-
sion at the other, owing to the resistance of the water to the
fluids emitted. As far, perhaps, as the direction of the
motion of the swarm-spore is concerned this explanation would
account for it; but I very much doubt whether an end-
and exosmotic process, however active it may be, would of
itself account for the quick and often extremely rapid move-
ment of these spores. The vibration of the cilia which, in
my opinion, plays the principal part in the movement of the
spores, is explained by Nageli to be the natural consequence
of the currents in the water, the cilia being so delicate as
necessarily to be affected by the slightest fluctuations. In con-
tradiction to this, however, I must remark, that the fre-
quently rather long cilia are almost always extended, with a
lashing motion, in the same direction as that in which the
spores proceed ; which could not be the case with such deli-
cate and flexible organs unless they exerted a power of spon-
taneous motion. I cannot dispute, however, that the immo-
tility and impassiveness of the vegetable cell-membrane, as
Nageli properly remarks, is a general law without any excep-
tion, but I am by no means satisfied, that from this motionless
and impassive or rigid membrane are developed the motile cilia
of the swarm-spores. With respect to this, however, Nageli
argues, that even the vegetable spermatic filaments have an
impassive form, and advance merely in consequence of their
turning around their axis. To this I would object, that the
remarkable and very active motions of the vegetable spermatic
filaments, according to the most recent discoveries of Thuret,
Decaisne, and Suminski, are caused by two or several long
motile cilia which are attached to one extremity of these
P 2

200 SIEBOLD ON UNICELLULAR PLANTS AND ANIMALS.

entirely impassive spermatozoids.* Jn this we perceive an
important distinction between the formation and movement of
the vegetable and animal spermatic filaments, the former being
self motile, whilst the latter are moved only by the aid of
vibratile cilia.

It appears that Négeli is inclined to raise a distinction be-
tween vegetable and animal cilia, principally because otherwise
it would be necessary to assume the existence of contractility
in the former. I would maintain, however, that neither the
vegetable nor the animal cilia, between which I can perceive
no difference, are to be regarded as delicate contractile fila-
ments. In the actively-moving vibratile cilia particularly, as
well as in the animal spermatozoa, the movements proceed in
a way as yet altogether unknown; from a simple waving and
bending action, unattended by any shortening or lengthening,
and without any thickening or attenuation of the filament,
whilst the delicate non-vibratile, but undoubtedly contractile
(animal) filaments, during their movement become at the same
time shortened and thickened, or elongated and attenuated.
It is true that Unger describes, with respect to the ciliated
organ of Vaucheria, a retraction and shortening of the cilia or
spores, from the influence of a solution of sugar. But the
result of this experiment in no way goes to show the con-
tractility of these excessively delicate cilia, as it was not
observed during their life, and must undoubtedly be con-
sidered as a process of decomposition ; in support of this is
the fact, as Unger expressly remarks that the coarser cilia,
on the branchie of Unio, though, indeed, rendered motionless
by the same treatment, nevertheless do not become shortened.

The movement of the swarm-spores in general have only a
short duration. After the spores have come to a state of
rest, they usually become attached by the hyaline-ciliated ex-
tremity, and the locomotive faculty is for ever lost. That
these spores should move toward the light, cannot be wondered
at when we consider the hungering after light so generally
observable in the vegetable kingdom.

With respect to the motion of the spores, I must again re-
mark upon a phenomenon above described by Nageli, and
which is one of a very evident nature, viz., that these bodies
are impelled involuntarily, and proceed always in one direc-
tion, and without resting. If in this course they strike upon

* Vide Thuret on Chara; Ann. d. §. Nat. Bot., tom. 14, 1840, p. 67,
Pl. 7, and Decaisne and Thuret. /b, tom. 3, 1845, p. 8, Pl. 1 & 2; .n
various fucoids. Suminski, Entwickelungs-Geschichte der Farrnkraiiter.
Berlin, 1848, p. 11, Pl. IL.

SIEBOLD ON UNICELLULAR PLANTS AND ANIMALS. 201

any larger object, they do not retreat from it frightened as it
were, as do the Infusoria not unfrequently, but they impinge
directly upon the obstacle, remain close to it, and continue
their motions, according to the number and arrangement of
their ciliary apparatus, in a rotatory or vibratory way for a
little time longer, as if they aimed at overcoming the obstacle
by force, until at last, probably in consequence of the death
of the cilia, they bécome still, and germination goes on, so
that the swarm-spores belonging to certain multicellular Alge
make use at the same time of one and the same object as a
basis, to which they become affixed by warty processes, pro-
jected from the hyaline extremity.

In several unicellular Alga, particularly in those which
“swarm ”’ united into families, that process endures very much
longer: in some species, indeed, the “ swarming” families
continue almost their whole life through in the same con-
dition ; this is the case in the Volvocina, in which, even during
the “‘ swarming,” new “‘swarming” families are produced, or
do not come to a state of rest until the period of [true] pro-
pagation has arrived.

How strikingly the swarm-spores, both of unicellular and of
multicellular Alga, resemble certain Monadina and Crypto-
monadina is well seen in the representations of various spores
of this kind, given by Unger, Thuret, Solier, and Nageli. It
is well known that Unger (‘Die Pflanze im Momente der
Thierwerdung,’ 1843, figs. 8, 10) discovered that the motion
of the spores in Vaucheria clavata was effected by a general
ciliary investiture, a discovery which was confirmed by Thuret
(‘Recherches sur les Organes locomoteurs des Spores des
Algues, Ann. d. Sci. Nat. Botan.,’ tom. 19, 1843, Pl. II.,
figs. 29, 30). The same observer (ib., Pl. X., figs. 13, 14, 18)
noticed a circlet of cilia in the “ swarm-spores”’ of Prolifera
(Conferva) vesicata, alternata, tumidula, and Candolii, as did
Solier (Mémoire sur deux Algues Zoosporées, ib., tom. 7,
1847, Pl. LX., fig. 8-1] and 23) in Derbesia (Bryopsis) ma-
rina, and Lamourouxit. According to Thuret (ib., Pl. X.,
figs. 1-3 and 7-10), the zoospores of Conferva glomerata
and rivularis swim about with the aid of two lash-like cilia,
and those of Chetophora elegans, on the other hand, with four.
Nageli figures the zoospores of Apiocystis Brauniana, Nag.,
of ‘Tetraspora explanata, Kiitz., and Characium Nagelii, Br.
with two such cilia, Fresenius (Zur Controverse tiber die
Verwandlung von Infusorien in Algen, 1847, figs. 1-3) de-
tected in the biciliated zoospores of Chatophora elegans, also
the (so termed) red “eye.” According to the highly interest-
ing researches of a A. Braun (Verbhandl. der Schweizerischen

902 SIEBOLD ON UNICELLULAR PLANTS AND ANIMALS.

naturforsch. Gesellschaft zu Schaffhausen, 1847, p. 20), a
formation of spores occurs in Hydrodictyon utriculatum, in
consequence of which, zoospores, with four long cilia and a
red granule in the interior, swim about with great activity.

How extensively, again, these zoospores are present among
the Alge, is shown in the numerous researches of my friend
A. Braun, here in Freiburg. 1 can here only refer to his
memoir just quoted, which will show what an abundance of
materials he has already collected on this important subject,
and how interesting it would be to science were he to resolve to
publish these discoveries in their whole extent. From the me-
moir above noted it is to be gathered, that in Conferva glomerata
and fracta numerous spores, with two cilia and a (so called)
red “eye” spot, quit the mother-cell, through an opening
which is formed in a definite spot. In Ulothrix zonata, Kiitz.,
he saw formed in each cell from eight to sixteen spores, fur-
nished with four cilia and a large round “eye,” which escaped
through a lateral opening in the mother-cell, enclosed in a
delicate vesicular membrane, and did not swim about until
this membrane was ruptured. In Draparnaldia mutabilis,
Stygeoclonium tenue, and several allied species, as well as in
Chetophora tuberculata, according to Braun’s researches, there
is in each mother-cell only a single red-eyed spore, with four
lash-like cilia. Braun, moreover, confirms Thuret’s pre-
vious observations on other Conferve, ‘and describes also the
propagation of the unicellular algan plant, Characium Sieboldi,
Br., in the spindle-shaped mother-cell of which, sixteen and
more spores with two cilia become developed; and also men-
tions a Protococcus versatilis, Br., the cells of which, after
their attaining a certain size, divide into two motionless cells,
which, by repeated segmentation, divide into four, and these,
in like manner, into eight ; which last—fourth generation—
swims about for a short time by means of four vibratile cilia,
in order eventually again to go through the motionless cycle
of vegetation.

Another distinguished work, already several times quoted,
‘ Ralfs’ British Desmidiew,’ also treats of unicellular plants,
which have been confounded with lower animals, although in
a more limited sense, embracing only the Desmidiacez and
Closterina of Ehrenberg.

Respecting the remarkable process of segmentation, by which
most of the Desmidiacex are multiplied, Ralfs remark (p. 5)
that the segments gradually enlarge whilst they divide, but
that this multiplication by division has its limits, for, after a
certain number of generations, the individuals which had by
repeated division attained a certain size, at last perish.

SIEBOLD ON UNICELLULAR PLANTS AND ANIMALS. 203

~A most especial service has been rendered by the same
assiduous observer of the Desmidiacee in his investigation of
the process of conjugation in so very many of these unicellu-
lar plants. This process had been previously described by
him (Ann. Nat. Hist., vol. xiv., 1844, p. 258, P. viii, and
vol. xv., 1845, p. 153, pl. x.) in Tetmemorus granulatus, R.,
and Staurastrum mucronatum, R. In his recent work we learn
that the same proceeding takes place, besides the Closterina,
in many other Desmidiacee, viz. Hyalotheca, Didymoprium,
Spherozoma, Euastrum, Micrasterias, Cosmarium, and Xan-
thidium. In the moniliform Hyalotheca dissiliens, R., and
Didymoprium Borrert, R., the conjugation takes place in such
a way that two contiguous cells separate on the sides oppo-
site each other, and through the cleft their contents escape in
order to form a common sporangium. In the permanently
unicellular forms of the Desmidiez, with the exception of
certain Closteria already mentioned, two closely approximated
individuals dehisce transversely in the middle, and yield up
their whole contents to the formation of a single sporangium.

The sporangia of the Desmidiacee thus originating in
conjugation have for the most part a spherical form, and,
according to Ralfs (p. 10), in many species remain smooth
and unaltered, whilst in many others they become granulated,
tuberculated, or spinous, many eventually acquiring a Xan-
thidian figure.

It is to be regretted that Ralfs and Jenner have not as yet
succeeded in tracing the further development of the Desmi-
diaceze within these sporangia. From the coloured figures in
Ralfs’ work, it appears that the green contents of the sporangia
in certain Desmidiacez in time become red. Whether this
phenomenon be connected with a further development of the
contents, and perhaps corresponds with the transformation of
the Chlorophyll into an orange-coloured oil, as described by
NaAgeli, I must leave undecided. [Here follows an abstract of
Mr. Ralfs’ excellent observations on the question of the
vegetable or animal nature of the Desmidiex; but as his
valuable work is probably in the hands of, or attainable by,
all who may feel an interest in knowing what such an ac-
curate observer and careful*reasoner says upon this subject,
it seems needless here to give the abstract. |

A very important discovery recently made by Thwaites
(Annals Nat. Hist., vol. xx., p. 1847, p. 9, and 343, pl. iv.
and xxii.), showing that conjugation takes place also in the
Diatomacee, cannot here be passed over. He observed in
Eunotia turgida and Zebra, Eby., as well as in LEpithemia
gibba, Kiitz., and Fragilaria pectinalis, &c., the following

204 SIEBOLD ON UNICELLULAR PLANTS AND ANIMALS.

remarkable phenomenon. Two individuals, closely approxi-
mated, dehisce in the middle of their long diameter, where-
upon four protuberances arise, which meet four similar ones
in the opposite frustule. These indicate the future channels
of communication by which the endochrome of the two
frustules becomes united, as well as the spot where is subse-
quently developed the double sporangium, or rather the two
sporangia. ‘The masses formed by the coalescence of the two
portions of endochrome shortly become covered each with a
smooth cylindrical membrane—the young sporangia. These
gradually increase in length, retaining nearly a cylindrical
form, until they far exceed in dimensions the parent frustules,
and at length, when mature, become, like these, transversely
striated upon the surface. Thwaites terms these new indi-
viduals, sporangia, comparing them probably with the
sporangia produced by conjugation in the Desmidiee. In
all these processes of conjugation there occurs at the same
time an abundant secretion of a clear and gelatinous substance,
which entirely envelopes the Diatomaceze when in the act of
conjugation, and thus retains them in connexion. I recognize,
however, so far a difference between this mode of propagation
and the conjugation of most of the Desmidiew, that in
the conjugation of the Diatomacez, neither a diminution
nor increase in the number of individuals takes place ;
only Fragilaria pectinalis offers an exception to this: im the
conjugation of which Thwaites saw only a single new and
larger individual to be formed. It must at the same time
here be noticed, that the new individuals produced in this
remarkable way, not only exceed the parent individual
in size, but also that they frequently exhibit a totally dif-
ferent form, so that there is no doubt but that in time
many of the recognized Diatomacee will prove to be the
so-termed sporangia of others. Thus Thwaites supposes
that Epithemia vertagus, Kiitz., is the sporangium of Eunotia
turgida, Eby.

From all the hitherto described unicellular Algae, Pedias-
trum differs most essentially in its interesting mode of propa-
gation, It is known that the plants described by Ehrenberg
as Micrasterias constitute families, consisting of 4, 8, 16, 32,
or 64 cells, which are disposed in the same plane, and united
into discoid or stellate fronds. Ehrenberg, as usual, speaks
of the polygastric apparatus, of the ovaries, and testes of these
organisms ; all of which organs appear to be brought naturally
into harmony with those of the Infusoria. With respect to
the propagation, Ehrenberg does not appear to have made any
direct observations, for what he describes as spontaneous

SIEBOLD ON UNICELLULAR PLANTS AND ANIMALS. 205

division of the single cells is, at any rate, incorrect. Two
short remarks, made by Turpin and Meyen, on the propaga-
tion of Pediastrum borganum, are dismissed by Ehrenberg
with equal brevity, although Meyen’s notice is deserving of
much consideration. What Turpin would appear to have
seen, with respect to the dispersion of a mass of fine spores
from the swollen extremities of the marginal cells of the
same species of Pediastrum, and which he even figures
(‘Mem. du Muséum d’Hist. Nat.,‘ Vol. XVI., 1828, p. 320,
Pl. XIII., fig. 22), is assuredly deceptive, because, as I am
assured by A. Braun, the enlargements at the extremities of
the Pediastrum in question are formed of thickened cellulose,
and probably incapable of dehiscence. On the other hand, it
appears from what Meyen says, that he had seen the remark-
able propagation of the Pediastra. His words are as follows
(‘ Nov. Act. Acad. Nat. Curios.,’ Tom. XIV., Pars II., 1829,
p- 774): ‘“ When old, the cells gradually burst, and the aggre-
gated mass of spores escapes endowed with a motive faculty ;
the spores very soon come together, become loosely connected
with one another, and, at the same time, lose the power of
motion. The perfect individuals have no motion.” That
there is some truth in this statement I am satisfied from the
close investigations which have been instituted by A. Braun
on the subject of the propagation of the Pediastra. He was
able to show me under the microscope, in Pediastrum granu-
latum, Kiitz., that by segmentation of the cell-contents, 4, 8,
16, or 32 spores are developed in the interior of each nell of
this Alga, which spores, after the dehiscence of the cells,
escape from them enveloped in a delicate, colourless mem-
brane, and after moving about confusedly, but actively, for
some time, arrange themselves in one plane in a stellate
manner, after which they gradually become quiescent and
adhere to each other. The delicate external membrane with
which these spores are at first surrounded gradually dis-
appears, probably being dissolved. This motion and arrange-
ment within the delicate tunic of Pediastrum granulatum
agrees in all respects with the highly interesting phenomena
observed by Braun in the second form of spores of the like-
wise unicellular Alga Hydrodictyon utriculatum. In this
case also, the very numerous spores which are produced in
each cell exhibit, if not active motions, yet a sort of quivering
movement that lasts more than half an hour, until at last
becoming applied to each other, they come to a state of rest,
and being connected by means of the dilated mother-cell,
arrange themselves into a new network, which becoming free

206 SIEBOLD ON UNICELLULAR PLANTS AND ANIMALS.

by the solution of the mother-cell, acquires the original dimen-
sions, and after about three weeks forms new spores.*

From this report on the more recent labours of botanists in
the field of the lower vegetable world, it may be seen how
important and indispensable the study of this branch of
botanical knowledge must be for those who would success-
fully apply themselves to researches connected with the lower
animal kingdom.

[The above paper by Von Siebold is not here given only for
its intrinsic value, but because it has been thought that it
would afford a pretty fair exposition of the views entertained
at the time it was written by the more modern school of
microscopical observers, and that it would serve as a starting-
point from which to measure future progress in investigations
of the nature of those to which it relates ; and that so far it
might be useful and desirable to give it a place in an early
number of the Microscopical Journal. It is proper, however,
to notice that there are several points in which it will be
seen—chiefly, however, from subsequent observation—that the
author has fallen into error. |

On the Psorospermia and Grecarin&. Millers Archiv,
1851, pp. 221. By D. F. Leyore.

Tue Psorospermia are microscopical corpuscles of a peculiar
kind, which may be generally characterized, in the full-grown
condition, as rounded organisms, having a sharply-defined
outline, with or without a tail-like appendage. They are
flattened and lenticular in figure, and one pole is usually acu-

* For further and later information (1851) on the subject not only of
Hydrodictyon, but generally on that of the formation, spores or gonidia in
the lower Algw, and for a most philosophical and comprehensive view of
the whole matter, no better source can be consulted than A. Braun’s
(Betrachtungen tb, die Erscheinung der Verjiingung in der Natur. Leipzig,
1851, pp. 364), ‘Considerations on the Phenomenon of Rejuvenescence in
Nature,’ a work of which it is impossible to speak too highly, and to which
there will be frequent occasion of reference by all who are interested in the
important subjects of which it treats. Nor can any one consider himself
at all aw niveau on the subject of the propagation and development of the
lower Algw who has not studied the elaborate paper by Cohn (Zur
Naturgeschichte des Protococcus pluvialis, Kiitz.), ‘On the Natural
History of Protococcus pluvialis,’ contained in the 22nd vol. of the Nov.
Act. Nat, Curios., 1850, which is a complete repertory of all known on the
subject up to that period, and moreover exhibits many new points in a
most clear and satisfactory manner. These valuable papers are of too
great length for insertion in this Journal, but it is intended hereafter to
siveasuflicient abstract of each to place the facts and reasoning contained
in them fairly before the English reader.

LEYDIG ON PSOROSPERMIA AND GREGARIN®. 207

minate; and towards this pole several internal vesicles con-
verge in a symmetrical:manner. These creatures were disco-
vered by Joh. Muller in 1841 (Mull. Arch., 1841, p. 477).
He found in a young Pike minute round cysts in the cellular
tissue of the muscles of the eye, in the substance of the scle-
rotica, and between this and the choroid coat. ‘The contents of
the cysts was a whitish substance, which, when examined mi-
croscopically, was found to consist of peculiar elements—the
** Psorospermia.” [A detailed notice of these observations is
given in the ‘ Microscop. Journal,’ vol. ii. p. 123, and in the
‘ Brit. and Foreign Med. Rev.,’ January, 1842.] In the follow-
ing year the same observer (Miiller’s Arch., 1842, p. 193)
discovered parasitic corpuscles in the swimming bladder of a
Gadus callarius, which, although specifically distinct from the
Psorospermia, approached very near the latter in their organi-
zation. ‘They resembled in general a smooth ventricose Navi-
cula, and consisted of two elongated cases applied to each
other at the cavity, and with an elliptical outline and convex
outer surface. They were in part free, in part enclosed in
masses within a tunic. Similar cysts, containing ‘‘ Psoro-
spermia,” have been found by Leydig in several species of fish,
and in all parts nearly of their bodies, and even in the blood
contained in the heart (p. 223), and in the peritoneal cavity.

Some facts, however, observed by him, connected with this
subject, which came under his notice in 1850, during some
researches on the cartilaginous fishes, served to throw a more
general light upon these mysterious forms.

In the gall-bladder of a Squatina angelus, there occurred, in
the bile, and in large quantity, peculiar forms of various
organization, but which were manifestly developmental forms.
1. Rounded vesicles, consisting of a delicate membrane and a
consistent fluid. The latter was of a yellow colour and con-
tained a multitude of also yellow granules. 2. Other vesicles
presented, besides these, other elements of a new kind. In the
middle of the granular contents were several perfectly trans-
parent cellules. Small vesicles had only one of these cellules,
larger ones as many as six. 3. Other parent vesicles, again,
exhibited, besides their membrane, a granular contents and
secondary vesicles, containing Psorospermia, always one in
each secondary vesicle. 4. In the latter form, finally, the
secondary vesicle had attained a large size, and the Psorosperm
floated im a spacious clear chamber, which occupied nearly
the whole of the parent cyst. Besides these motionless cysts,
there were numerous free Psorospermia in the bile.

He found, upon examination, very similar things in other
fishes of the same class,—as in Spinax vulgaris, Scyllium

208 LEYDIG ON PSOROSPERMIA AND GREGARIN~.

canicula, Torpedo narke, and Raja batis, in which the Psoro-
spermia differed from the more usual form, in their being
grooved or ribbed.

It was very remarkable that the above-described organisms
were never met with in any other part or tissue of the body
than the gall-bladder or biliary duct.

With respect to the nature of these bodies, Leydig is in-
clined to think that the cyst should be regarded as belonging
to the family of the Gregarinz, and that the « Psorospermia ”
must be looked upon as generically analogous to the “ Pseudo-
navicelle,” which have been observed to be generated within
the Gregarine.

The question next arises as to the existence of similar
Gregariniform organisms producing Psorospermia, in fresh-
water fishes. Leydig thinks there is reason to suppose that
the animalcule discovered by Valentin in the blood of Salmo
fario is a Gregarina. Moreover, John Miiller and Leydig
have observed two or three ecaudate Psorospermia i in Leu-
ciscus dobulst, enclosed in a cyst. Whence it might be sup-
posed that secondary cells may be developed within one of
Valentin’s Hamatozoa, after it has been conveyed, in the
course of the circulation, to one organ or another; in which
cells Psorospermia may originate. With the growth of the
latter the granular contents of the Gregarine gradually dis-
appear, which are thus transformed into cysts filled with
Psorospermia. Such a cyst would then be equivalent to a
Navyicella-receptacle,

The author then proceeds to discuss the vexata questio
of the true nature of the Gregarine ; and, adverting to the
conflicting views of Kdélliker and Bruch, declares himself in
favour of the latter, which assumes, as above stated, that the
Gregarina is a transformed Filaria, or Anguillula.

In the intestine of a large species of Terebella he was en-
abled to observe the most distinct transition between Filaria-
like nematoid worms and Gregarine. The forms of the
latter which he observed, not once only but many times,
were—1l. A Gregarina of from 0:02” to 0:04!” long, which
had the form of an elongated sac, rounded at one extremity,
and sharp at the other. The ponteuts were those usual in
the Gregarinew, a consistent fluid with a corpuscular sub-
stance, which did not occupy the pointed end, and imbedded
in this a clear vesicle with a nucleus. 2. A Gregariniform
creature, of a spindle-shaped figure, closely resembling Gre-
garina Torebelle, Koll 3. A Gregarina, generally resem-
bling the prec eding, differing only in two particulars. The
internal substance is afranged in longitudinal streaks, and

ON THE TRANSMISSION OF INTESTINAL WORMS. 209

the body, instead of being straight, is more or less curved
ateach end. 4. The same form, but with the body more
elongated, vermiform; and, for the first time, exhibiting
motion. 5. A very pretty nematoid worm, about 0.10” long ;
blunt at one end, sharp at the other; the contents in longi-
tudinal streaks, as in the two preceding forms, but with the
spaces between them wider. Its motions are very active.

Leydig is induced, by considerations of the above facts, and
by other reasons, to believe that the Gregarinz are not per-
fect animals, but ‘a link in the series of development of the
Helminthes,” as Henle expresses it. Another question, how-
ever, arises: do the Gregarine become changed into Filaria-
form worms, or is it that the Filaria-like worms are meta-
morphosed into Gregarine? Although at first inclined to
consider the former as the true state of the case, Leydig is
now disposed to follow Henle and Bruch, and adopt the
latter view; otherwise it would seem impossible to account
for the formation of the ‘ Pseudo navicella”’ and ‘¢ Psoro-
spermia ” within the Gregarine.

Experiments on the Transmission of Investina, Worms. By
M. Heresr. Annales des Sciences Naturelles, tome xvii.

No. 1, p. 63.

Tue author’s experiments appear to have been directed only
to the Trichina spiralis, or allied species. He recognizes
three species of this genus. The first, corresponding in all
respects with that discovered in the human body by Hilton,
Owen, and Bischoff, was met with in the voluntary muscles of
a large old cat. Shortly afterwards he met with a second
species in the mesentery of Strix passerina. It occurred in
the substance of the muscles, and also in the mesentery, in
which situation the worm occupied yellowish tubercles about
the size of a pin’s head. This Trichina is distinguished not
only by a body double the size of that of the other, but
principally by the abnormal form of its extremities, The
enlarged head terminates in a short conical point, the surface
of which is verrucose, and the attenuated tail seems to be
furnished with two papillary protuberances at the extremity,
as well as with an infundibuliform opening. The third
species was met with by the author in 1848, in the muscles
of a full-grown dog. The cysts were very small, scarcely
visible to the naked eye. The vermiculi enclosed in them
were much smaller, but in other respects resembled those
of the first species, from which, consequently, it may be

910 ON THE TRANSMISSION OF INTESTINAL WORMS.

considered doubtful whether they are really specifically
distinct.

In November, 1850, a female Badger, about two years old,
that the author had kept partly on vegetables and partly on
the remains of the animals which he had dissected, died. He
discovered the presence of an infinite number of Trichine in
all the voluntary muscles. This case seemed to afford a
favourable occasion for new researches relative to the origin
and formation of these worms.

In 1845 the author had failed in an experiment in the
transmission of the Trichine. In that experiment he intro-
duced thirty cysts containing living vermiculi between the
skin and lumbar muscles of a young tat. At the end of a
month the cysts were found fixed in their situations, but the
vermiculi were dead. On the present occasion he proceeded
differently. The flesh of the badger was given to some young
dogs about six weeks old, and was devoured by them in the
course of a few days. One of the puppies was sent into the
country, and allowed to be at large, exposed to all the external
atmospheric influences. On the examination of the other
two, made on the 10th and 18th of February, 1851, all the
voluntary muscles were found to be as abundantly infested
with the Trichine, as were those of the badger which the
puppies had devoured three months before. The length of
the cysts was 133-1000th, their width 73-1000th, and the
size of the vermicule 1166-100,000th of a line. It remained
to ascertain the condition of the third dog, which was done
after an interval of nine months, or in the beginning of
November, 1851. The dog was adult, and in all respects
vigorous and healthy in appearance.

‘On the 11th of November the author exposed the sterno-
mastoid muscle, which, to the naked eye, exhibited nothing
extraordinary ; under the microscope, however, Trichine
could be recognised in such vast numbers that ina portion of
the muscle, weighing two or three grains, as many as six
cysts could be detected; the length of these cysts was
33-1000th, their width 833- 10, 000th, the length of the worm
33-100th, and its diameter 1166- 100,000th of aline. Now,
as these worms are not common, wid their appearance may
be considered as a rare phenomenon, there can be no doubt
that their presence in the three dogs in question was con-
sequent upon their having eaten the. flesh of the badger. The
extreme tenacity of life in these parasites, which is not appa-
rently affected by either heat or cold, must be considered as
favourable to their propagation ; but the great difficulty is
with respect to the mode in which the ova of these worms,

KOLLIKER ON A KNOWLEDGE OF THE LOWER ANIMALS. 211

very minute and highly elastic, it is true, but which never-
theless present solid particles and determinate forms, reach
the blood-vessels from the alimentary canal. For the abundant
and simultaneous presence, as well as the uniform distribu-
tion of these Trichine in all the voluntary muscles, appear to
justify the supposition that their ova are conveyed to the
various spots in which the worms are lodged, in the course
of the circulation of the blood. This question the author does
not attempt to decide.

s

Contributions towards a Knowledge of the Lower Animals. By
A. Kotter. Abstracted from Siebold and Kolliker
Zeitsch. Vol. I., p. I.

Tuts paper contains a description of various species of Gre-
garina, with detailed observations on their structure and
position in the animal kingdom. The following is a summary
of the conclusions at which the author arrives :—

1. The Gregarine are animals.

2. The simple Gregarine consist indubitably of a single
cell ; their membrane corresponds to a cell-membrane, their
contents to a cell-contents, the vesicle to a nucleus, the granule
or granules within it to a simple or broken-up nucleolus.

3. The Gregarine which are constricted at the middle also
correspond, most probably, with a single cell of a peculiar
kind.

4. There is no reason whatever for supposing that the
Gregarine are not perfect animals.

5. The cysts containing pseudo-Navicelle arise, in the gra-
nular contents and vesicles, probably in a transformation of the
Gregarine, that is, if they are to be looked upon as younger
Gregarine.

6. This being supposed, then the pseudo-Navicelle of the
older cysts or receptacles are probably to be regarded as the
germs of the Gregarine, which become either Gregarine
themselves, or, what can hardly be considered probable, ani-
mals of another form, which, in the latter case, is to be regarded
as the perfect form of the Gregarina.

7. The occurrence of two nuclei or two cells in the interior
of certain Gregarine has either a relation to their multiplica-
tion, or is an introduction to their transformation into pseudo-
Navicellz-receptacles.

8. The connexion of certain Gregarine may depend upon
a division of the pseudo-Navicelle, on the supposition that
these are the germs of Gregarina, or may originate in a sort

212 KOLLIKER ON A KNOWLEDGE OF THE LOWER ANIMALS.

of longitudinal and transverse division of the youngest Gre-
garina,

Thirty-five species are enumerated: to which several have
since been added by Leidy (Proceed. of the Acad. of Nat.
Sciences of Philadelphia, vol. iv. p. 229, or Annals Nat. Hist.,
2nd ser., vol. y. p. 317). Further observations also on the
subject may be found by Stein in Miiller’s Archiv (August,
1849), or Annals Nat. Hist. (vol. v. p. 480); Henle (Jahres-
bericht tiber Histologie, 1845, p. 49); C. Bruch (Sieb. and
K6ll. Zeitsch., vol. ii. p. 110), who describes minutely the
mode in which the pseudo-Navicellz are formed, by a segmen-
tation of the contents of a Gregarina, or of a process analogous
to segmentation. He was unable to observe what further be-
came of the Navicelle, which, in the Earth-worm, upon the
Gregarine inhabiting which Bruch’s observations appear to
have been principally made, certainly do not undergo any fur-
ther change. He is inclined to think that the Gregarinz are
Filaria in a quiescent state. He considers, therefore, that the
Gregarine afford another instance of what has been termed
*¢ Alternation of Generations ;” and upon the supposition that
the Gregarina is an altered Filaria, it follows that the former
cannot be regarded, properly, as a unicellular animal, seeing
that the latter represents an entire vitellus, that is, an aggrega-
tion of cells. ‘To these observations of Bruch, or, more pro-
perly speaking, of Henle, relative to. the transformation of
Filariz into Gregarine, Kdlliker (op. c., p. 113) replies, that
such an alternation of generations among the Nematoid Worms
is elsewhere unknown, regarding, with Steenstrup and Siebold,
that Miescher is incorrect in his observation of the transforma-
tion of the Filaria piscium into a globular membranousenvelope,
from which, at a subsequent period, a trematoid animal, and
finally, a Yetrarhynchus proceeds. Although the change of
a Filaria into a Gregarina is not an impossible circumstance,
before we admit such a thing, it is first necessary to inquire
whether the facts stated may not be otherwise explained. It
is by no means proved that the Anguillula-like animal noticed
by Henle, and termed by Bruch Filaria ; the Proteus tenax of
Dujardin (Ann. d. 8, N., 2nd ser., tom. iv. p. 354); the Sa-
blier protéiforme of Suriray (Ann. d. S. N., 2nd ser., tom. vi.
p. 356), isreally a Nematoid Worm. Kolliker is more inclined
to regard it as an Infusorium allied to Opalina, Proteus, &e.
If this be the case, there is, according to him, nothing extra-
ordinary in its transformation into a Gregarina, and finally
into a Navicella-receptacle. He goes on to say (p. 114) that
he maintains his original opinion that the Gregarine are per-
fect animals, which are of the nature of simple cells, and pro-

KOLLIKER ON A KNOWLEDGE OF THE LOWER ANIMALS, 213

pagated, like many Infusoria, by germs, the so-called Navi-
celle. He allows, however, that there are many points in their
economy still requiring elucidation. [With reference to K6l-
liker’s observation, that no instance of alternation of genera-
tions is as yet known among the Nematoid Worms, we may
notice a paper by Mr. Busk in the ‘ Microscopical Transac-
tions’ for 1846, vol. ii. p. 65, Pl. X. on Filaria Medinensis,
in which the author adduces facts and reasons which induce
him to think it not improbable that an alternation of genera
tions may take place in the case of that Entozoon. |

VOL. I. Q

@ abe.)

REVIEWS

Dre PFLANZENZELLE, DER INNERE Bat UND DAS LEBEN DER GEWACHSE,
&c. (The Vegetable Cell, the Internal Structure, and Life of Plants,
worked over in original comparative, microchemical researches). By
Dr. Hermann Scuacut. Berlin, 1852, roy. 8vo., 672 pp., and 20
plates with 390 figures, partly coloured.

Tuts work, for which the author has recently received a de-
coration from the King of Prussia, was briefly alluded to in
a former part, and we here take occasion to lay a somewhat
extended account of it before our readers. Dr. Schacht’s
book is one that has attracted great notice, and will have
considerable influence on the progress of the microscopic ex-
amination of vegetable structure, but this will not be so much
the result of originality of the matter contained in it as of the
method pursued in the investigations and in the exposition of
them. In fact there are few new points, and the merits of
the work rest chiefly upon the industry and directness with
which the author has worked over the whole field of vegetable
anatomy under the point of view laid down in his title, that
of comparison of the tissues in the various classes, not merely
by simple inspection, but by parallel series of observations on
development, assisted by the systematic application of re-
agents for the determination of the chemical characters. The
mode of operation pursued is thus described in the Introduc-
tion (p. 7).

“In the first place, unless I had to do with simple cellular filaments,
as, for instance, in Conferve, I made the most perfect cross and long
sections I could, and examined them in water, with a strong objective and
a low ocular, ordinarily with system 9, and oculur 1 of my Oberhauser micro-
scope ; then drew all my important preparations most accurately, and also
frequently preserved the preparation in chloride of caleium for subsequent
comparison, noting at the same time everything which could not be ex-
pressed in the drawing. Next, I treated equally perfect sections with
solution of iodine, then with iodine and sulphuric acid; another equally
good section was then treated with the chloride of zine and iodine solution,
others with concentrated sulphuric acid, and others again with sugar and
sulphuric acid. After | had carefully observed the changes which each of
these re-agents produced on the sections, had drawn and noted them, I
boiled good cross and long sections in strong solution of potash, in a
porcelain saucer, allowing the ley to boil up once or twice over the spirit-
lamj; then taking out the preparation anJ laying it in water. Watch-
glasses, which do very well for maceration, are unfit for boiling prepara-

SCHACHT’S VEGETABLE CELL. Obs

tions, as the heat increases too quickly, and they split. The preparations,
after being washed, were examined in water, then with the addition of
each of the above re-agents.”

The maceration by Schulze’s process was applied to sec-
tions and to fragments of tissue. The re-agents were applied
again to the preparations, and both in those boiled, and those
macerated, the effects were often different from those on the
simple sections. These operations were performed on cells of
all kinds, and in a great variety of plan's; moreover the
same re-agents were applied in the same way to the young
and the perfectly developed structures of the same plant.
With this brief notice of the nature of the experimental
observations we pass to a summary of the most important
contents of the book as regards micrographical points.

[he first section is devoted to a general Jutroduction, an
account of the method of research and .a description of the
chemical elements of the tissues.

Sect. IH]. is devoted to the Esseutial parts of the Vegetable
Cell, namely, the Cell-membrane, the Protoplasm, the Nucleus,
the Primordial Utricle, and the Cell-sap with its contents.

In reference to the Cell-membrane we find no new point of
importance ; the author’s observations are opposed to the
speculations recently revived by Agardh, jun., that the primary
membrane is composed of coherent fibres, and in this we are
quite in agreement with him, His observations are opposed
to Schleiden’s idea, that the lenticular space between the
contiguous “ pits” of the Coniferz arises from the formation of
an air-bubble ; he always found the space occupied by fluid.
The details on the secondary deposits, the results of which
confirm the views of Von Mohl in opposition to Harting and
Mulder, will be found very instructive.— Protoplasm is always
to be detected by the rose-colour it takes with sugar and
sulphuric acid (the colour sometimes does not make its ‘ap-
pearance for ten minutes),.— Nucleus. Tire author believes that
this body is never absent from young cells. In this view we
are inclined to differ from him ; indeed the invariable detec-
tion of nuclei in vegetable cells, by German pliysiologists,
has always been a mystery to us, and which only seems ex-
plicable by supposing that every roundish granule or globular
mass of plotoplasm is a nucleus or a nucleolus. Schacht does
not venture to affirm the existence of a membrane of tlie
nucleus at any pertod.—The Primordial utricle is stated, in
agreement with Mohl, Henfrey, Mitscherlich, &c., to be con-
stricted gradually in the increase of cells by division, Cedl-
sap and Contents.—Starch—the author agrees with Schleiden
in his view, that starch grains are formed by successive de-

Q 2

216 SCHACHT’S VEGETABLE CELL.

posit of iayers around a nucleus. This is a very difficult
subject, and one which is not nearly worked out yet. Chloro-
phyll-globules are stated to be without a membranous enve-
lope, as supposed by Niaigeli, Cohn, and Géppert. With
regard to this, as also the similar membrane asserted by
Nageli to exist around starch, we often have seen what may
easily be taken for such a structure, but cannot decide whether
or not it is an optical deception.

Sect. III. treats of the Oriyin of the Vegetable Cell, which is
described, in accordance with recent writers, as taking place
in two ways, viz: 1. Free cell-formation and 2. Parietal cell-
formation, by division of the primordial utricle of the parent
cell. He mentions under the latter head that the special
parent-cells are not formed in the development of the pollen
of CEnothera, or the spores of Anthoceros levis (to which
might have been added those of Marchantia polymorpha, and
probably others). In Cambium-layers the cell-development
is effected by the division of the primordial utricle of the
parent-cell. Tue paragraph on the development of the leaf
of Sphagnum is very interesting, and the more instructive
from the ease with which the observations may be repeated.*
A paragraph is also devoted to the history of development of
the spores of the Trufile, which accords with our own ob-
servations.

Sect. 1V. Zhe Growth and Nutrition of the Cell-membrane.
The author believes that the primary membrane enlarges by
expansion, and becomes thinner thereby, but does not actually
increase in substance by intussusception of molecules, as some
have supposed. The walls are thickened by secondary de-
posits, always laminated, except in the case of spiral bands, -
in which no layers have yet been detected.

Sect. V. The Cells of Vegetables as connected together. n-
tercellular substance is believed to exist, but to a much
smaller extent than is generally imagined ; sometimes even
not optically demonstrable. The real intercellular substance,
as it occurs sparingly in collenchyma of rinds, &c., is coloured
yellow by iodine. The bulky deposits at the angles of
cells, often called intercellular substance, are, in almost all

cases, as pointed out by Von Mohl, stratified deposits be-
longing to the cell-cavity, but rendered apparently exterior
by changes occurring during growth. Cuticle is a subject on
which a great deal has been written lately, not to a very de-
cisive effect. Dr. Schacht adopts Von Mohl’s distinction
between cuticle, the thin layer, coloured yellow by iodine,

* The curious structure of the cell wall in the leaf of Sphagnum renders
that plant an interesting microscopic object.

SCHACHT’S VEGETABLE CELL. yaw

found on the surface of plants, and the cuticular layers on the
inside of the outer wall of the epidermal cells, which layers
make up the greater part of the thickness of the hard epi-
dermis. The external cuticle is regarded by our author as an
excreted product, in which conclusion he rests greatly on the
certainly strong case of the elegantly-marked cuticle of spores
which, like those of the Truftie, originate free in the cavity
of a parent-cell. This section is very important in the pre-
sent stage of inquiry on this head, not, indeed, as striking out
new light, but as a testimony to facts which as yet have not
been repeated by many observers.

Sect VI., on the kinds of Vegetuble cell and Vegetable tissues,
is, perhaps, the most interesting in the work. ‘The structures
are divided into free cells, viz. :--1. The Swarming-filament
cells (Spermatozoid cells) of the Cryptogamia ; 2. the Sporés
of the Cryptogamia (under which are included the Swarming-
spores—zoospores —of the Conferva, more properly called
Gonidia); and, 3. the Pollen grain ;—and Cellular tissues,
viz.: 1. Cells and tissues of Lichens and Fungi; 2. Cells
and tissues of Alge; 3. Parenchyma and its cells; 4. Cam-
bium and its cells; 5. the Vessels of Plants; 6. Wood and
its cells; 7. Liber-cells (containing much original observa-
tion); 8. the Epidermis ; 9. the Stomates; 10. the Appen-
dicular organs; and,11. Cork. Our space does not allow
our entering into the multitude of new and interesting facts
ascertained by our author by the application of the micro-
chemical method to these objects; but his pages will repay
attentive study. It is, perhaps, scarcely worth while to advert
to a curious error, for which the author has been much, and
with a narrow-minded spirit, ridiculed by Walpers, viz., the
statement that cotton is a liber-fibre It argues certainly a
neglect of literature, but it does not follow because the author
never saw cotton in its native capsules that he does not look
well into the plants growing round about him. ‘The author
denies the old statements concerning milk-vessels, and, as in
a separate paper published a year or two ago, declar:s that
they are all simple or ramified liber-cells, analogous to those
long known in the A pocynacez.

Sect. VII. Vhe Thickening Ring, or Cambial Ring. In
this section the author sets up a new doctrine, of much im-
portance in vegetable anatomy, if correct, namely, that the
cambium of the ring where a stem expands each year, is dis-
tinct from that of the vascular bundles, and that these may
either coincide with the former or not, which las important
bearings in respect to explication of the growth of many stems;
but we are here again compelled to refer to the original,

218 SCHACHT’S VEGETABLE CELL.

Sect VIII. comprehends the Vascular bundles.

Sect. IX. Stem, Leaf, Root, Bud, and Flower, ‘This sec-
tion contails many speculative opinions, which it does not
belong to our office to criticise here The same may be said
of Sect, K on the Growth of Plants, and Sect XI., the Gene-
ral Vital Phenomena of Plants, except nm regard to the para-
grapls in the latter, on the movements ae the protoplasm
(circulation) in cells, which are very elaborate and instructive.

Sect. XH. The Cell an Organ of Propagation. This
contains a good summary of the facts recently made out in
this field, examined from an original point of view. In regard
to the Phanerogamia, our author is a firm supporter of
Schleiden’s doctrine, that the embryo originates in the end of
the pollen-tube. He obtained the prize of the Dutch Aca-
demy on this subject a few years back, and, although almost
the only advocate besides Schleiden at the present time of
this view, like that author he is exceedingly positive. We

believe him to be wrong, from personal examination even of +

the cases on which he lays greatest stress, and, considering
the circumstances, we are not inclined to think the matter
one longer open to question; for we have had occasion to
learn that Dr. Schacht met Dr. Hofmeister, one of the most
earnest advocates of the other view, to compare preparations,
and they parted mutually Micattdee ck so that his preparations
could not be quite so decisive as he asserts. It may be re-
marked that Mr. Smith’s celebrated case of Calobogyne ad-
mits of a probable explanation, under the view that the em-
bryonal vesicle originates in the embryo sac, but not under
the hypothesis that it is formed in the end of the pollen-tube.

Sect. XII, and last, treats of the Death of the Vegetable cell.
In an Appendix the authen gives some account of the applica-
tion of the polariscope to the microscope; but here he does
not afford any new lights; in fact the use of that instrument
is quite new to him, A more important contribution is a
tabular view of the microscopic characters of the Coniferous
woods.

In conclusion of our imperfect sketch of the chief contents
of this work we cannot help expressing our admiration of Dr.
Schacht’s drawings, which are real drawings and not dia-
grams ; moreover, the manner in which they are lithographed
—printed in colours— is a triumph of the art. It is curious
to compare this volume with some of the dingy “ sugar-
paper” products of the German press of a dozen years ago. All
vegetable anatomists who read German ought to possess this

work ; and even simple microscopists will find it a mine of
curious and interesting subjects for observation,

A. H.

(rvrOEben)

Reports oF Juries. ExXxuisirion oF WorkKS oF INDUSTRY OF ‘J,
Nations, 1851. Class X., Section Optical Instruments, Art.-!c
Microscopes.

AtHoues the Reports of the Juries of the Great Exhibition
have had a wide circulation, we have determined, at the
request of several of our subscribers, to make a few extracts
-from the Report on Microscopes, which, we think, will be
interesting to the readers of our Journal. The introduction
to this Report contains some interesting facts on the history
of the construction of the microscope, but to these we have
not now space to allude. The following remarks on the
structure of the microscope are valuable :-—

“The powers varying from 1-inch to a quarter-inch focus, inclusive,
are by far the most generally useful in the whole range of microscopic
combinations, especially for educational purposes..

“It must be remarked that it is advisable that the angle of aper-
ture of the combinations should not be extended to its utmost possible
limit, when destined for the general purposes of natural history or ana-
tomical investigation.

“ Combinations of high power, and extremely extended angles of aper-
ture, are excellent in developing one class of test objects, viz. niinute lines
or dots on plane surfaces, and admirably demonstrate the high perfection
to which such glasses are capable of heing carried by scientific opticians ;
but such combinations, with a less angle of aperture and more penetrating
power, are far more generally useful and valuable to the minute anatomist
and the naturalist.

‘¢ Tn regard to the brass-work, we may observe that the qualities espe-
cially requisite in the stand of a microscope are simplicity of construction,
portability, combined with sufficient weight to ensure safety and steadi-
ness, with smoothness and accuracy of action in all the working parts,
and such a construction as to distribute any tremor that may be com-
municated to the instrument equally over its body, stage, and other
working parts. These desirable points are admirably attained in the form
suggested by Mr. George Jackson, and adopted by Messrs. Sinith and
Beck, Ross, and other makers. For purposes of delineation, Nachet’s
(France, No. 1870) form of prism is more advisable than that of Wollas-
ton’s, as the former, having one reflection less than the latter, presents the
image to the eye in an erect instead of an inverted position.”

With regard to the form here said to have been suggested
by Mr. George Jackson, we have the authority of that pentles
man for stating that a microscope, in which the body was
attached to a saddle travelling on a bent triangular bar, was
originally made by Mr. Ross, and figured by him in the
article ‘ Microscope,’ in the ‘Penny Cyclopedia.’ Mr. Ross,
it appears, afterwards abandoned this form, when Mr. Jackson
again took it up, and, having obviated most of its defects, it
has since been adopted by Messrs. Smith and Beck and other
makers. The following remarks on the instruments exhibited
at the Great Exhibition will be read with interest :—

220 REPORTS OF EXHIBITION JURIES.

“‘ Ross.—A microscope, the mechanical parts of which are exceedingly
«ood: the movements are very smooth and true; the stand is on a plan
which is solid and steady, and at the same time not cumbrous. The
object-glasses are constructed with different kinds of glass in the different
compound lenses, forming a combination so as to double up the secondary
spectrum, and this is done so well that scarcely any separation of colours
can be detected. The angular apertures of the object-glasses examined
are as follows :—-

1-inch focal length, 27° aperture.

3-inch 35 60° 5
1-5th-inch 5% 113° #5
1-8th-inch ee IOS 6

1-12th-inch ‘ 135° 8

“‘ Both the half-inch and the one-eighth of an inch foci are purposely
made of smaller proportionate aperture than the quarter-inch or the one-
twelfth of an inch, as in all lenses of large aperture the image becomes
indistinct from the slightest change of focus, and so, unless an object be an
absolute plane, it is impossible to see the whole field tolerably distinct
at once with an object-glass of large aperture. In the set examined, the
inch, the half-inch, and the one-eighth of an inch, are intended for the
general examination of objects ; and the one-fourth and one-twelfth of an
inch for the examination of minute structures.

‘** SmirH and Beck.—A microscope, the stand of which in appearance is
not highly finished, but their forbearance to expend time and money on
elaborately finishing the non-working part has been adopted on the strong
recommendation of some of the eldest naturalists in London, in order that
students may acquire instruments with first-rate glasses at the least
possible expense, and that such instruments may be brought within the
compass of those whose means are limited. The stand is excellent in prin-
ciple : the body, stage, and appliances beneath are all carried on one stout
cast bar, on the recommendation of Mr. G. Jackson, by means of which
the centering of the achromatic illumination is rendered easy and certain,
and on any tremor being communicated to the instrument, it is equally
distributed over the whole of the working parts.

“The lever motion to the stage of this instrument is the most easy
and venerally useful that has yet been applied. If used with the right
hand, while the quick and slow adjustments to the focus are worked with
the left, there are no animalcule that cannot be 1eadily followed, however
fitful and rapid their movements; and any globule of blood pursuing its
course through the most tortuous of the capillaries, can be steadily and
easily traced, and every alteration of its form observed during its passage
through these minute vessels. The field of view may also be swept
horizontally or perpendicularly, and the most delicate micrometrical
measurements made with great ease and precision. This stage is the
invention of Mr. Alfred White; the rabbitted groove on which the body
moves was suggested by Mr. G. Jackson, at whose recommendation the
fuicruin of the stage movement was fixed to a spring, instead of to a rigid
bar. The simplicity and efficiency of the whole of this stand is highly com-
mendable. The object-glasses examined were of first-rate quality, and
were as follows :—

2-?rd-inch focus of 28° aperture.
4-10th-inch _,, 70° to 75° aperture.
4-10th-inch ,, 60° aperture.

1-5th-inch ,, LOO° to 105° aperture.

“They are beautifully corrected for spherical aberration, but the se-
condary speculum has not been much diminished. The half-inch focus

REPORTS OF EXHIBITION JURIES. 221

of 70° aperture is a wonderfully fine combination, easily showing objects,
considered difficult for a one-eighth inch focal length a little more than a
year since, and bearing the application of the higher eye-pieces in an un-
precedented manner.

“There are two tables with revolving tops, by which the microscope
can be turned readily round for the convenience of examination by dilfer-
ent observers, and thus rendered a social instrument. The microscopes
are furnished with portable silver reflector and annular condenser, which
exhibit transparent objects upon a dark ground. (This invention was
made by Mr. Wenham, and Smith and Beck claim its first exeention.)

VarLEY AND Son.—A microscope, the stage of which is moved by
parallel rods, with ball and socket joints, which gives an equable motion
in all directions, and is specially adapted for the examination of living
objects. A second microscope is exhibited, adapted for receiving vials in
which ayuatic plants or animalcule may be kept in a living state for any
length of time. The plant is secured to one side of the vial by a piece of
cork, and thus is within the reach of the microscope. ‘The vial is kept full
of water, and is only corked when used, at which time it is held in a
jacket to cut off all extraneous light; a dark chamber projects from it
opposite to the magnifier, so that a single beam of light may be made to
fall upon the part under examination. A third microscope, of a simple
construction, is also exhibited, chiefly intended for beginners.

“« King.—-A microscope stand, with micrometers and goniometers. It
has a pyramidal tripod, with stage traversed in rectangular planes by mi-
crometer screws. The parts of this instrument are so arranged that its
weight is equally distributed over the base, and when inclined at its
working angle, the principal weight is below the joint of suspension, and
the stand is steady and good. The traversing-stage is furnished with divided
scales and verniers. The workmanship throughout this instrument is of the
first order. It is furnished with many ingenious applications of subsidiary
instruments, and of apparatus speciaily adapted to the examination of
objects by polarized light, and goniometric apparatus for measuring the
angles of microscopic crystals. The mode of illumination, by a prism
worked into convex spherical surfaces, is also worthy of notice.

“¢ Prrrcnarp.—An old-fashioned achromatic microscope, with indifferent
object-glasses. The working of the mechanical parts is very good. This form
of instrument is that which led the way in the great advance that has been
made in the microscope by the introduction of achromatic object-glasses.

Lapp.—A microscope furnished with chain and spindle movements, in
place of rack and pinion. This movement has been applied to the micro-
scope many years since, by Mr. Julius Page. The motion is smooth, and
totally free from loss of time, and is likely to stand well the effects of
constant use.

“ PriscHER.—A large microscope stand, which is good for its price,
but unnecessarily large and inconvenient for use.

“ Jackson, E. And W.—Plain and excavated slips of glass, sections of
tubes of various forms, for the construction of cells for mounting wet
preparations, and thin glass for covering them, of various thicknesses.
These materials are exceedingly useful for scientific microscopists.

“ Hupsox.—Microscopic objects intended for the use of the medical
student, physiologist, and naturalist.

“ Herr.—A variety of admirably-injected microscopic objects, illus-
trating the utility of the microscope to the physiologist.

“« PouLron.—Some well-executed microscopic objects, with drawings to
illustrate their structure.

‘“¢ SparK,—Microsconic objects, mounted in gutta percha cells, instead
of glass ; and also slides for exhibiting opaque objects.

222 REPORTS OF EXHIBITION JURIES.

“ Syarp.—A set of high power lenses, ten in number, for a microscope
from one-tenth to one-hundredth of an inch focal length.

“ SHADBOLT.—A_ sphero-annular condenser, for concentrating light on
transparent objects while under microscopic examination, the object alone
being illuminated whilst the field of view is dark.

“The principle of this condenser was suggested by Mr. J. F. Wenham,
of Brixton, in his parabolic condenser. Mr. Shadbolt’s condenser carries
out Mr. Wenham’s principle, with the advantage of superior reflecting
arrangements, greater facilities of construction, and less liability of de-
rangement.

«© NaTcHET (France).—The object-glasses, though inferior to both those
of Ross, and Smith and Beck, are by far the best of the foreign ones,
They vary from a focus of one inch to that of one*eighteenth of an inch.
The following were examined ; that with—

1-18th of an inch focal length, has an aperture of 134°
1-8th ae pe t08°
_ 1-5th - 2 88°

“ In all of them the spherical aberration is not corrected ; and although
the method of adjusting by the separation of the lenses, invented by Ross,
is adopted, yet the system is such that they are not correct at any dis-
tance. The wor kmanship of the stand is very good; ana there are two
ingenious forms of microscopes exhibited. One has the object-glass below
the stage, with the tube inclined at a convenient angle and a reflecting
prism for the examination of chemicals, or for dissecting transparent ob-
jects under fluids. ‘The other is a dissecting microscope, with the body
inclined in a convenient direction, and the image erected by reflecting
prisms, so as to enable an observer to look in a convenient position whilst
dissecting an object in fluid, which must be kept horizontal.

“« Some microscopes excellent for their price were exhibited by Bernard
(France). These instruments were the cheapest in the Exhibition, though
none were of the first order.

** CHEVALIER (France).—A microscope, with indifferent object-glasses.
The workmanship of the mechanical part, however, is very good, the mode
of mounting is excellent, and the instrument is convenient for all kinds
of microscopic observations.”

Other instruments are referred to, but neither their excel-
lence of workmanship nor optical power demand notice. Of
preparations for the microscope, and microscopic drawings,
there were many. Amongst the latter named in the Report,
we may mention those of Mr. Leonard, who has largely
contributed to the illustration of microscopic objects Of
preparations, Mr. Topping exhibited an extensive series both
of vegetable and animal structures,

** BourGOGNE (France) exhibited a case of microscopic objects prepared
in the usual manner. They are mounted in Canada balsam, and consist
of sections of wood, and entomological and other preparations, with a
selection of salts to illustrate the polarization of light.

“ Noserr (Prussia), of Barth, has exhibited his wonderful tracings on
glass. The plan adopted by him is to trace on glass ten separate bands at
equal distance from each other, each band being composed of parallel
lines of some fraction of a Prussian inch apart: in some they are 1-1000th,
and in others only 1-4000th of a Prussian inch separated.

‘ee The distance of these parallel lines form parts of a geometrie series ;
thus—

os

BENNETT ON CLINICAL MEDICINE. 223

0-001000 line.
0°000857
0°000735_,,
0°000638
0:000540 ,,
0-000463
0000897
0°000340
0000 292
0000225 _ ,,

** To see these lines at ali it is necessary to use a microscope with a
magnifying power of 100 diameters; the bands containing the fewest
number of lines will then be visible. To distinguish the finer lines it
will be necessary to use magnifying power of £000, and then the lines
which are only 1-47000th of an inch apart will be seen as perfectly traced
as the coarser lines. Of all the tests yet found for object-glasses of high

“power these would seem to be the most valuable. hese tracings have
]

tended to confirm the undulating theory of light, the different colours of
the spectrum being exhibited in the ruled sjaces according to the separa-
tion of the lines; and in those cases where the distances between the lines
are smaller than the lengths of the violet light waves, no colour is per-
ceived ; and it is stated that if inequalities amounting to ‘000002 line

occur in some of the systems, stri;es of another cclour would appear in
them.”

Aw Inrropuction 'ro Citsicat Mepictne, By JoHN HucHes BEyNert,
M.D. Second edition. Edinburgh. Sutherland and Knox.
To those commencing tle study of the medical profession
this little book will ie found very valuable. Few of the
manuals that have been published with the same object in
view are so much up to the time as this little work by Dr.
Bennett. We are induced to give it a notice in our pages,
as out of the six lectures of which it consists two are devoted
to the Microscope as a means of diagnosis. Nor do we
think the space thus occupied disproportionate to the just
value of this instrument in the hands of the medical practi-
tioner. A successful treatment of disease, let practical men
say what they will, can only be insured by an accurate know-
ledge of disease; and there can be no accurate knowledge of
diseased tissues or morbid actions but by the aid of the
microscope. It must not, however, be supposed that the
microscope is an instrument easily used; that all a man has
to do in order to profit by its Pordlations is to purchase an
expensive apparatus at one of our great opticians, As with
the eye itself, the practice of observation with the microscope
demands a careful education. Only by instruction under a
careful teacher or a systematic course of private observation
can any one expect to use this instrument with success,
Whether for public courses or private study, Dr. Bennett’s
book will supply a good outline of the objects that ought to

224 BENNETT ON CLINICAL MEDICINE.

be examined by a medical man. The principal physical cha-
racters to be regarded in microscopic examinations are de-
scribed in the following passages :—

“1. Shape.—Accurate observation of the shape of bodies is very neces-
sary, as many of these are distinguished by this physical property. Thus
the human blood globules, presenting a biconcave round disk, are in this
respect different from the oval corpuscles of the camelid, of birds, reptiles,
and fishes. The distinction between round and globular is very necessary
to be attended to. Human blood corpuscles are round and flat, but they
become globular on the addition of water. Minute structures seen under
the microscope may also be likened to the shape of well-known objects,
such as that of a pear, balloon, kidney, heart, ete. ete.

“2. Colour.—he colour of structures varies greatly, and often differs,
under the microscope, from what was previously conceived rezarding them.
Thus the coloured corpuscles of the bluod, though commonly called red,
are, in point of fact, yellow. Many objects present different colours,
according to the mode of illumination ; that is, as the light is reflected
from or transmitted through their substance, as in the case of certain
scales of insects, feathers of birds, etc. Colour is often produced, modified, or
lost, by re-agents, as when iodine comes in contact with starch corpuscles,
when nitric acid is added to the granules of chlorophyle, or chlorine water
affects the pigment cells of the choroid, and so on.

“3. Edge or Border.—The edye or border may present peculiarities
which are worthy of notice. Thus it may be dark and abrupt on the field
of the microscope, or so fine as to be scarcely visible. It may be smooth,
irregular, serrated, beaded, etc. etc.

“4, Size-—The size of the minute bodies, fibres, or tubes which are
found in the various textures of animals can only be determined with ex-
actitude by actual measurement in the manner formerly described. It will
be observed, for the most part, that these minute structures vary in dia-
meter, so that when their medium size cannot be determined, the varia-
tions in size from the smaller to the larger should be stated Human
blood-globules in a state of health have a pretty general medium size ; and
these may consequently be taken as a standard with advantaze, and bodies
may be described as being two, three, or more times larger than this
structure,

“5. Transparency.—This physical property varies greatly in the ulti-
mate elements of numerous textures. Some corpuscles are quite dia-
phanous, others are more or less opaque. ‘Lhe opacity may depend upon
corrugation or irregularities on the external surface, or upon conten s of
different kinds. Some bodies are so opaque as to prevent the transmission
of the rays of light, when they look black by transmitted light, although
they be white, seen by reflected light. Others, such as fatty particles and
oil globules, 1efract the rays of light strongly, and present a peculiar
luminous appearance,

“6, Suwrface.—Many textures, especially laminated ones, present a
different structure on the surface from that which exists below. If, then,
in the demonstration these have not been separated, the focal point must be
changed by means of the fine adjustment. In this way the capillaries in
the web of the frog’s foot may be seen to be covered with an epidermic
layer, and the cuticle of certain minute fungi or infusoria to possess
peculiar markings. Not unfrequently the fracture of such structures enables
us, on examining the broken edge, to distincuish the difference in structure
between the surface and the deeper layers of the tissue under examination,

“7, Oontents.—The contents of those structures, which consist of enve-
lopes, as cells, or of various kinds of tubes, are very important. ‘These may

BENNETT ON CLINICAL MEDICINE. 225

consist of included cells or nuclei, granules of different kinds, pigment
matter, or crystals. eccasionally their contents present definite moving
currents, as in the cells of some vegetables, or trembling rotatory mole-
cular movements, as in the ordinary globules of saliva in the mouth.

“8. Hifects of Re-agents.—These are most important in determining
the structure and chemical compusition of numerous tissues. Indeed, in
the same manner that the anatomist with his knife separates the various
layers of a texture he is examining, so the histologist, by the use of re-
agents, determines the exact nature and composition of the minute bodies
that fall under his inspection. ‘Thus water generally causes cell formations
to swell out from endosmosis ; whilst syrup, gum-water, and concentrated
saline solutions cause them to collapse from exosmosis. Acetic acid pos-
sesses the valuable property of dissolving coagulated albumen, and, in con-
sequence, renders the whole class of albuminous tissues more transparent.
Thus it operates on cell walls, causing them either to dissolve or become
so thin as to display their contents more clearly. Ether, on the other
hand, and the alkalies, operate on the fatty compounds, causing their solu-
tion and disappearance. The mineral acids dissolve most of the mineral
constituents that are met with, so that in this way we are enabled to tell
with tolerable certainty, at all events, the group of chemical compounds to
which any particular structure may be referred.”

Short accounts are given in the book of the appearances
of the saliva, milk, blood, pus, sputum, vomited matters,
faeces, uterine and vaginal discharges, mucus, dropsical
fluids, urine, and cutaneous eruptions and ulcers. In a
manual of 130 pages, of course no detail could be expected
on these subjects. What is given bears the stamp of being
the result of the author’s own investigations on the subjects
he treats, and will be found all the more valuable as coming
from one who is a good physiologist as well as a diligent
practical physician.

A Synopsis oF THE British Diatromace®. By the Rev. WILLIAM SMITH.
The Plates by TurreN West. Vol. I. London: Van Voorst.

Amongst the organic beings whose existence the microscope
bas demonstrated, few possess a higher interest than the group
now known as the family of Diatomacee. Appearing every-
where as the first-born of Life, wherever inorganic matters
are fit for its development, these beings were looked upon sus-
piciously by early observers, and, whilst regarded by some as
doubtful in nature, were leohod upon by others as evidences
of spontaneous generation. Their siliceous structure, which
was early known, served to give them a strange resemblance
to the mineral world, whilst, although endowed with motion,
they presented no traces of organic tissues. The labours,
however, of Ehrenberg set at rest the question of their belong-
ing to the mineral world, and showed how great their claims

226 A SYNOPSIS OF THE BRITISH DIATOMACE.

were to be regarded as members of the animal kingdom. Their
relationship to the Desmidez was always apparent, and these
beings were placed by Ehrenberg also in the animal world.
But as evidence of the vegetable nature of the Desmidee
multiplied, so it became evident that the Diatomaceze must
follow. The fact that both these families produce sporangia
as the result of conjugation in common with a large number
of the conferye, give them a common character which could
hardly be assigned to beings belonging to both the animal
and vegetable kingdoms. Hence Diatomacee are now com-
monly regarded as plants. But whilst zoologists have readily
admitted this argument, the botanist on other grounds has
rejected the Diatomacee from his domain, Schleiden, in his
‘ Principles of Botany,’ refuses, on the ground of the compli-
cated and unplantlike structure of Diatomacee, to recognise
them in the vegetable kingdom. Organisms which have thus
constituted the battle-field of systematists must have more
than usual interest for those who employ the instrument by
which alone they can be discerned. But independent of this,
there is scarcely any class of objects that present more beauti-
ful forms, and none that invites the microscopist to a higher
trial of the greatest powers of his instrument. On these
accounts the present work could hardly fail to be popular
from the subject on which it treats, and when to this is added
the well-known reputation of the author for researches upon
the Diatomacew, we need hardly say that the work needs no
recommendation from ourselves.

The present volume is illustrated with a frontispiece and
thirty-one plates, all of which have been drawn from nature
and engraved by Mr, Tuffen West. As this gentleman has
executed all the plates for the Microscopical Journal, our
readers have at once the opportunity of forming an opinion
of the merits of the illustrations to Mr. Smith’s work. We
have no hesitation in pronouncing them to be superior to
anything we know that has been published on the subject.
By far the larger proportion of the illustrations are devoted
to new species which have now been published for the first
time. We may perhaps be allowed to doubt the permanence
of many of these forius, although we do not the propriety of
recording them. There is at present so great a shaking
amongst the dry bones of species which systematists have
recorded that we cannot but feel that some of Mr. Smith’s forms
may turn out transitionary. Not more than half the species
are gone through in the present volume. It includes the well-
known genera Cocconeis, Campylodiscus, Surirella, Nitzschia,
Navicula, Stauroneis, Pleurosigma, Synedra, Cocconema, and

A SYNOPSIS OF THE BRITISH DIATOMACE. 227

Gomphonema and others, whilst the larger and even more
typical genera of Bacillaria, Meridion, Diatoma, and their
allies, are yet to come.

The work, in addition to the description of the species,
with drawings of each, contains a general Introduction, in
which the habitats, structure, functions, and the modes of col-
lecting and preserving specimens are entered into. From the
section on habitats we select the following extract :—

They inhabit the sea or fresh water, but the species peculiar to the one
are never found in a living state in the other locality, though there are
some which prefer a medium of a mixed nature, and are only to be met
with in water more or less brackish. The latter are often found in great
abundance and variety in districts occasionally subject to marine influences,
such as marshes in the neighbourhood of the sea, or the deltas of rivers,
where, on the occurrence of high tides, the freshness of the water is
affected by percolation from the adjoining stream, or more directly by the
occasional overflow of its banks. Other favourite habitats of the Diato-
mace are stones of mountain streams or waterfalls, and the shallow pools
left by the retiring tide at the mouths of our larger rivers. They are not,
however, confined to the localities I have mentioned,—they are, in fact,
almost ubiquitous, and there is hardly a roadside ditch, water-trough, or
cistern, which will not reward a search, and furnish specimens of the tribe.

The indestructible nature of their epiderm has also served to perpetuate
the presence of these forms in numerous localities, from which their living
representatives have long since disappeared. Districts recovered from the
sea, in the present or other periods of the earth’s history, frequently contain
myriads of such exuvie forming strata of considerable thickness. Such
deposits have been found in Bohemia, in the neighbourhood of Berlin, in
various districts in Italy, and in several of the American States. The city
of Richmond in Virginia is said to be built upon a stratum of Diatomaceous
remains 18 feet in thickness, and extensive tracts in the Arctic Regions
Have been found covered with similar relics of a former vegetation.

Nor are we without examples, though on a less extensive scale, in our
own country. The ancient site of a mountain lake in the neighbourhood
of Dolgelly, localities of a somewhat similar kind near Lough Island-
Reavey, in Down, and Lough Mourne, in Antrim, have furnished large
supplies of some of the forms described in the present work. Several
deposits of a like kind have been met with in Scotland, and have also con-
tributed to enrich the present volumes. The extreme minuteness of the
organisms which have furnished such remains, and the hardness of their
material, have rendered the substance formed by their aggregation, a useful
agent in the mechanical arts, in which it has been employed to confer a
polish upon hard surfaces. It is from this circumstance that the material
known as Tripoli derives its value as a polisher of metals ; and the Dolgelly
deposit has to some extent been employed for a similar purpose.

One of the most singular instances of the preservation of Diatomaceous
forms occurs in regard to Guano, so largely imported as a manure from
Peru and Africa.

Mr. Smith regards the siliceous skeleton, as it has been
called, as perfectly homologous with the epidermal tissues of
many vegetable organs, and the botanist will immediately
recall to mind such instances as Deutzia scabra, Equisetum,

228 A SYNOPSIS OF THE BRITISH DIATOMACE.

and many of the palms and grasses in which silex enters into
the epidermal tissues. It is true in these higher plants we
have nothing so perfectly regular as the siliceous plates of
Diatomacee present, but it seems to be a law both in the
vegetable and animal kingdoms, that the lower we descend in
the scale of organization the more tendency do the inorganic
constituents exhibit to submit to the inorganic law of crys-
tallisation or symmetry of form. The following is a brief
summary of Mr. Smith’s view of the nature of the siliceous
part of these structures :-—

The epiderm of the Diatom consists of two siliceous plates or valves,
usually of the most perfect symmetry. When first produced, these valves
are closely applied to each other, and the line of junction forms a suture
along which the valves readily separate during the process of self-division
which speedily follows the perfect formation of the cell. It seems to be a
law with these organisms, that no portion of the internal cell-membrane
can be exposed to the free action of the surrounding water, without secret-
ing a siliceous epiderm ; the moment the valves become separated in the
process of self-division, we consequently find that the secretion of a third
plate of silex commences. This plate forms a band between the valves,
and will for convenience sake be atterwards spoken of as the Connecting
Membrane. As self-division is continually going on while the frustules
are ina healthy or growing state, it is rare to find a specimen in which
the valves are not in some degree separated, and consequently in which
there is not more or less of a connecting membrane.

Mr. Smith describes “a distinct movement of the granular
particles of the endochrome closely resembling the cell-con-
tents in Closterium Lunula.”

This circulation has not, however, the regularity of movement so con-
spicuous in the Desmidiex, and is of too ambiguous a character to furnish
data for any very certain conclusions, save one, viz. that the Diatom must
be a single cell, and cannot contain a number of separate organs, such as
have been alleged to occupy its interior ; since the endochrome moves
freely from one portion of the frustule to another, approaching and receding
from the central nucleus unimpeded by any intervening obstacle.

On the movements of the entire frustule Mr. Smith has no
satisfactory theory to offer. He has never been able to dis-
cover any semblance of a motile organ. He suggests that
the movements may depend on endosmotic and exosmotic
action. We must pass over the sections on self-division and
classification, and give a concluding extract from the direc-
tions for collecting and preserving the Diatomacea :—

Let him provide himself in the first place with the necessary apparatus.
For the field, this includes a good stock of small wide-mouthed bottles,
that each gathering may be kept perfectly distinct ; a long rod or stick, to
which can be attached a small muslin net ; a cutting hook, of about three
inches in length ; and a broad flat spoon: the first, to collect such speci-
mens as float upon the surface, or are held in suspension by the water ;
the second, to remove the larger Algw which may be covered with parasitic

A SYNOPSIS OF THE BRITISH DIATOMACE2. 229

Diatoms ; and the third, to skim the surface of the mud for those which
lie at the bottom of the pool.

He will probably find, notwithstanding every care, that his specimens
are mixed with much foreign matter, in the form of minute particles of
mud or sand, which impair their value, and interfere with observation,
especially with the higher powers of his instrument. These substances
the student may remove in various ways ; by repeated washings in pure
water, and at the same time, profiting by the various specific gravities of
the Diatoms and the intermixed substances, to secure their separation ;
but more particularly, by availing himself of the tendency which the
Diatomacez, in common with all growing plants, possess, of making their
way towards the light. The free forms may be thus procured in a tolerably
clean state; all that is necessary being, to place the gathering which
contains them in a shallow vessel, and leave them undisturbed for a
sufficient length of time in the sunlight, and then carefully to remove
them from the surface of the mud or water.

Having performed these operations, which a little practice will render
comparatively easy and generally successful, the next proceeding is to
preserve the specimens in such a manner as to render them suitable for
examination by the microscope at any future time. This may be done in
various ways, according to the nature of the species and the precise object
desired.

The simplest method, and the one most generally useful to the scientific
observer, is simply to dry the specimens upon small portions of tale, which
can at any time be placed under the microscope, and examined without
further preparation ; and this mode possesses one great advantage, that
the specimens can be submitted without further preparation to a heat
sufficient to remove all the cell-contents and softer parts, leaving the
siliceous epiderm in a transparent state.

We trust Mr. Smith will not keep us waiting long for his
second volume, and we feel that we have said enough to
show that no one can for the future study the Diatomacee
without having recourse to this work, which will, we are
assured, become a standard one on the subject.

A History or Inrusor1sL ANIMALCULES LIVING AND Fossin. ‘Third
Edition. By Anprew Prircuarp, M.R.I. London: Whittaker & Co.

Turis work contains the largest amount of information on the
subject of animalcules to be found in the English language.
Its foundation seems to be the ‘ Infusionsthierchen’ of Pro-
fessor Ehrenberg, and his classification has been adopted in
the systematic part of the work. The author has added a
large quantity of matter from other sources, more especially
from the writings of English naturalists on the subject. It
is illustrated with twenty-four plates, embracing figures of a
very large proportion of the Infusoria after Ehrenberg, Ralfs,
Gosse, Smith, and others. With all the attention and expense
that have evidently been bestowed on this book one is pro-

voked to find it so carelessly got up. The introductory
VOL, I. R

230 HISTORY OF INFUSORIAL ANIMALCULES.

history contains a great quantity of very useful information,
but it is not well arranged. Every one, however, who is
employed in investigating the forms of animalcules will find
here'a repertory of matter to assist him in his labours. We
are annoyed again at the perpetual misprints which, in a
costly book with pretensions like this, are quite inexcusable,
Who would expect to find our friend Mr. Bowerbank under
the cacophonious spelling of ‘ Brawerbank”? Mr. Brown’s
remarks on molecular movements are spoken of as the mol/e-
cular motions of Dr. R. Browne. An order Diamomacez is
recognised, and Linchens is a substitute for Lichens. Cur-
sorily glancing through the pages we have the following
instances of mispelling:—‘“‘ Monas_ crepuseulum,” “ an
Alge,” ‘ Eyistylis,” ‘ Ampileptus,” “ Infusionthierchen,”
“‘ Infusionsthierschen,” and we might add many more. We
make these remarks in no mere critical spirit, but with a
desire that a work which is, without doubt, the most important
one on the subject in our language, should, if it reaches
another edition, be rendered free from these eye-sores, which
must be annoying to every educated reader.

( 231 )

NOTES AND CORRESPONDENCE.

As many of your metropolitan readers may be glad to know
of localities in which microscopical objects may easily be
found, I beg leave to state for their information that the waters
of the New River, the ornamental water in St. James’s Park,
and the fountains in Trafalgar Square, will prove well worthy
of investigation.

During the last two months I have obtained from the New
River, near the City Road, Cocconeis clypeus, Cocconeis pedi-
culus, Fragillaria pectinalis, Synedra valens and lunaris,
Closterium Leiblinii, Odontidium mesodon, Navicula Hippo-
campus and amphirynchus, Hydatina senta, Surirella striatula,
an arborescent Vorticella with 38 animalcules, Tardigrada,
Gomphonema truncatum, and a Vibrio, the species of which,
from unfortunately losing the specimen, | could not de
termine.

From Trafalgar Square, abundance of common Navicule,
the Dytiscus, Lurco, Vorticella Convallaria and Campanula in
great profusion, especially on a beautiful specimen of Clado-
phora glomerata.

From the Regent's Park, Ameba (? diffluens), Aneurea
testudo, Gomphonema Sranechinn and minutissimum, Bacillaria,
Vorticella Convallaria, Paramecium Chrysalis, and the com-
moner Naviculz in incredible profusion. Hitherto I have only
tried the water at the southern side, near the ferry.

I may also mention that the small pools in fields at the
back of the Norwood Cemetery were very rich last October in
Volvox globator and the variety awreus, and in Green Hydras,
—J. M. R., Islington.

On the Capillaries of the Liver.—In the last part of Todd
and Bowman’s Physiological Anatomy a doubt is expressed
concerning the nature of the ultimate passages through which
the blood circulates in the liver. Whether the smallest
blood-vessels of this organ are true capillaries, that is, are
possessed of a single tunic like other vessels of this descrip-
tion, or whether the blood passes along mere spaces, or
channels formed by the hepatic corpuscles, so as to be in
actual contact with their cell-walls, is regarded by these
authors as a question yet to be decided.

Having at this time in my possession a portion of injected

rR 2

232 MEMORANDA.

human liver, in which I have no difficulty in showing the
smallest capillaries, and in demonstrating their tunic, the
following observations will, I hope, be considered worthy of
a place in your valuable Journal: first, because any doubt
proceeding from such high authorities cannot fail to unsettle
a point of minute anatomy which the microscope has satis-
factorily established, and thereby to weaken general confidence
in the results of all other microscopical observations ; and
secondly, because the supposed fact of mere blood-channels
existing in the liver whilst true capillaries are demonstrable
in other glands seems to depart too widely from a general law
to have even the sanction of probability in its favour.

The examination necessary to show the capillaries of the
liver is best made on a very thin slice of injected liver taken
from a part bordering on that where the injection begins to
fail, so that in the same slice there may be one part fully in-
jected, but of course without any extravasation, another in
which the vessels contain but little of the colouring matter of
the injection, and a third, immediately continuous with this,
in which the capillaries are empty. But, before examining
this section, it must have been submitted to a gentle current
of water trickling over it, in order that the biliary corpuscles
may be entirely washed away from the meshes of those capil-
laries which project from the thinnest part of it; so that these
vessels, being free in the field of view,-may be seen by trans-
mitted light, as a transparent object.

Such is the section from which the accompanying drawing
was taken by my friend Dr. Bristowe.

Portion of the Liver as seen by 1-8th of

an inch lens.

é a Capillaries filled with injection.
b Ditto imperfectly injected.
c Ditto containing no injection.

d d Meshes from which the hepatic corpuscles
have been entirely removed,

e Ditto with corpuscles in them.

In respect to their structure these capillaries differ but
little from those of other parts; their calibre in the liver I

MEMORANDA. 930

have always observed to be very unequal, arising most pro-
bably from the manner in which they are compressed by the
corpuscles which lie in immediate contact with their walls,
and fill up the areola produced by their numberless inos-
culations. Their average diameter is about 1-3000th of an
inch. Their tunic is remarkably thin and transparent, and,
so far as I have seen, without nuclei ; but in this respect these
vessels are not unlike the capillaries in many other parts.
The meshes are generally circular or oval, and about 1-1000th
of an inch in diameter, although some are larger and others
smaller.

The difficulty of displaying the capillaries of the liver I
believe to arise from the close connexion of the hepatic cor-
puscles with their walls (there being in this organ no visible
basement membrane), and the extreme fragility of the latter ;
so that the means employed to remove the corpuscles from
the meshes of the capillaries will break away the vessels
also. This, I think, will not be so likely to take place if the
part have been kept a few days before examined, and be
treated in the manner above described.

I may observe that Mr. Busk has examined portions of this
liver with me, and has allowed me to state that he entertains
no doubt whatever of the existence of a wall in the capillaries
of the liver as in other glands.—GeorcE Rainey, M.R.CS.,
Demonstrator of Anatomy and Microscopie Anatomy, St.
Thomas's Hospital.

On a peculiarity in the thickening Layers of Vegetable
Celts.—In the ‘ Botanische Zeitung’ of September 27, 1850,
Dr. H. Schacht described a peculiar appearance he had ob-
served in the secondary deposits of the wood-cells of Caryota
urens, Hernandia sonora, Phenix dactylifera, and Cocos bo-
tryophora, consisting of slits in certain of the secondary
layers, often taking a more or less spiral direction around
the cell-wall. These cracks, as they may be termed, were
often covered up again by subsequent deposits in the inside,
so that they become narrow canals, running in the thickness
of the wall formed by secondary layers. In examining some
cells of Hydrodictyon utriculatum recently, we observed phe-
nomena of the same kind; and as it appears likely that some-
thing of the same kind has given rise to J. G. Agardh’s*
idea of the cell-membrane generally being composed of fibres,
we have thought it worth while to direct attention to these
points. These slit-like marks are well seen in portions of
the cells of Hydrodictyon, which have been kept in chloride of

* De cellula vegetabili fibrillis tenuissimis contexta. Lund., 1852.

234 MEMORANDA.

calcium, and the spiral direction of them is very evident
towards the extremities of the cells. It is probable that a
similar structure will be found, on more careful examination,
on the walls of many of the Confervee, which become much
thickened.—ArtTuur Henrrey, March, 1853.

The Finder.—Take a flat bit of wood, box, or ebony, or it
may be ivory, half an inch longer and broader than your slides,
and about the eighth of an inch thick.

Along the top of this cement a bit of ivory, half an inch
wide and as thick as the general run of your slides, and cement
a similar bit of ivory on the left-hand end of it.

Now, it is obvious that your slide will exactly fit upon that
portion of the bit of wood upon which the slips of ivory are
not fixed. Next, in that part of the wood which is under the
middle of the slide, cut a hole an inch long adjoining the slip
of ivory, and three-quarters of an inch broad; then graduate
that part of the ivory which adjoins the hole to fiftieths of an
inch, and thin the ivory bevel from behind adjoining the hole,
to make the graduations transparently visible.

To make use of the finder, place your slide in it with the
left end of the slide close up to the shoulder at B.; then hap-
pening to observe an object—suppose a fossil Mavicula, for
instance, at a, which you wish to find again, bring it into
the centre of your field; then, with the vertical motion of
your stage, move the slide down till the graduated scale comes
into your field. Now, observe the number on the scale that
is in the centre of the field, and mark this number on your
slide “ Navicula! 35.”

When next you want to find this Navicula, put the slide as
before into the finder, bring the scale into your field, and 35
on the scale into the centre of your field ; then, by the vertical
motion of your stage gradually raise your slide till the object
which you are seeking comes into view.—JouNnN TYRRELL,
County Court Judge of Devon, New Court.

MEMORANDA. 235

On the History of the Vinegar Plant.—Much was said
and written on this plant about a year back, and we made a
long series of observations on it, confirmatory of the opinion
of Mr. Berkeley, that it is the mycelium of Penicillium glaucum,
but there are many interesting points in its history which we
cannot yet clear up. A curious fact has recently occurred to us.
A piece of the gelatinous mass was dried and kept for some
months, and then placed in a solution of refined sugar. After
remaining in a dark closet about three months, through the
winter, the solution is found still sweet, no trace of acid re-
action being given with litmus paper. The fructification of
the fungus is abundant, but the mass of mycelium is blood-
red, looking, in fact, like a mixture of half coagulated blood
and water. This brought to mind an observation made
some years ago, of red spots among mould upon decaying
paste, which were found to depend on innumerable minute
oval cells, with two granules (so-called nucleoli) in each.
These exactly resemble detached cells of the mycelium
(gonidia?), often occurring abundantly in the jelly of the
Vinegar plant; and, moreover, they are, in all probability,
the same bodies described and figured by G. Fresenius* as a
new species of fungus, occurring on starch jelly, under the
name of Cryptococcus glutinis. These structures are evidently
related to the “ blood on bread” Fungus described by Ehren-
berg, Montagne, and others.—Arruur Henrrey, March, 1853.

Mode of isolating Naviculz and other Test Objects.—
Having found the methods ordinarily employed very tedious,
and frequently destructive of the specimens, I adopted the
following plan :—Select a fine hair which has been split at its
free extremity into from 3 to 5 or 6 parts ; and having fixed
it in a common needle-holder by passing it through a slit in a
piece of cork, use it as a forceps under a 2-8drds of an inch
objective, with an erecting eyepiece. When the split ex-
tremity of the hair touches the glass slide, its parts separate
from each other to an amount proportionate to the pressure,
and on being brought up to the object are easily made to seize
it, when it can be transferred as a single specimen to another
slide without injury. The object is most easily seized when
pushed to the edge of the fluid on the slide.

Hairs split at the extremity may always be found in a
shaving-brush which has been in use for some time. Those
should be selected which have thin split portions so closely
in contact that they appear single until touched at their ends.

* PBeitrage zur Mykologie, von G. Fresenius. Heft Hl. Frankfort on
the Maine, 1852.

236 MEMORANDA.

I have also found entire hairs very useful when set in needle-
holders in a similar manner, any amount of flexibility being
given to them by regulating the length of the part of the hair
in use.—P. Reprern, Aberdeen.

Notice of a Binocular Microscope.—I devised last year,
and have lately constructed and used, a combination of glass
prisms, to render both eyes simultaneously serviceable in
microscopic observation

Behind the objective, and as near thereto as practicable, the
light is equally divided and bent at right angles, and made to
travel in opposite directions, by means of two rectangular
prisms, which are in contact by their edges somewhat ground
away. ‘Ihe reflected rays are received at a proper distance
for binocular vision, upon two other rectangular prisms, and
again bent at right angles; being thus either completely in-
verted for an inverted microscope; or restored to their first
direction for the direct microscope. These outer prisms may
be cemented to the inner by Canada balsam; or left free to
admit of adjustment to suit different observers, Prisms of other
form, with due arrangement, may be substituted.

I find the method is applicable, with equal advantage, to
every grade of good lens, from Spencer’s best sixteenth to a
common three-inch magnifier; with or without oculars or
erecting eye-pieces; and with a great enhancement of pene-
trating and defining power. It gives the observer perfectly
correct views, in length, breadth, and depth, whatever power he
may employ. Objects are seen holding their true relative
positions and wearing their real shapes. A curious exception
must be made. In viewing opaque solid bodies, with one eye-
piece to each eye, depression appears as elevation, and eleva-
tion as depression, forming a singular illusion. For instance,
a metal spherule appears as a glass ball silvered on the under
side; and a crystal of galena like an empty box. By tlie addi-
tional use of erecting eye-pieces the images all become normal
and natural, Match drawings of any solid object, made from
each eye-piece, by the aid of the camera lucida, when properly
placed in the common stereoscope, appear to stand out in
natural relief. These, if engraved and printed in the proper
position with respect to each other, might find an appropriate
place in books on the arts and sciences.

In constructing binocular eye-glasses, I use, for lightness
and economy, four pieces of common looking-glass, instead of
prisms,

With these instruments the microscopic dissecting knife can
be exactly guided, ‘The watch-maker and artist can work

MEMORANDA. 237

under the binocular eye-glass with certainty and satisfaction.
In looking at microscopic animal tissues, the single eye may,
perhaps, behold a confused amorphous or nebulous mass,
which the pair of eyes instantly shapes into delicate super-
imposed membranes, with intervening spaces, the thickness of
which can be correctly estimated. Blood corpuscles, usually
seen as flat disks, loom out as oblate spheroids. In brief, the
whole microscopic world, as thus displayed, acquires a tenfold
greater interest, in every phase exhibiting, in a new light,
beauty and symmetry indescribable. J. L. Rippert.— Silli-
man’s Journal.

On a new Method of illuminating Opaque Objects, for the
high powers of the Microscope; and ona new Achromatic
Condenser.—The front or terminal combination of the objec-
tive is made to condense light upon the opaque object by send-
ing rays of light from behind, through the marginal border of
the lens,

To accomplish this, a circular disk of fine plate glass, say
near a fourth or fifth part as thick as the diameter of the
lens, is bevelled on its outer margin, by grinding and polishing
to an angle of 45. A hole is drilled through the centre of the
disk, of a diameter, say two-thirds, three-fourths, or four-fifths
(dependent upon the angle of aperture), as great as that of the
lens. The margin of this Lole is also bevelled at an angle of
45°, down to a clean sharp edge. Both rings of bevels are
on the same side of the glass, so that, if considered as projected,
the lines would cross each other at right angles.

I find no insurmountable difficulty in giving an exquisite
form and finish to these disks. I mount and revolve the disk
on a good rose lathe ; at the same time the grinding or polish-
ing tool is revolved by an overhead motion, the spindle carry-
ing the tool being mounted upon a slide-rest, and admitting
of a protrusive movement at an angle of 45° to the axis of the
lathe.

The disk, being finished, is to be placed centrally behind
the lens, the bevelled margins looking backward, and the sharp
inner edge almost or quite touching the lens. Parallel rays
of light being thrown upon the disk, in the direction of the
axis of the objective, from below in the direct, from- above in
the inverted microscope, a ring of parallel rays is sent, by two
successive internal reflections, from the bevelled surfaces, so
that, with direction reversed, the light traverses the outer
margin of the objective, and by it is condensed upon the object
in focus.

{ tested this method of illumination in March last, su fli-
ciently to be satisfied of its great value; more especially

238 MEMORANDA.

where the objective is of very short focal distance, and where
consequently other means of illuminating opaque objects cannot,
on account of the nearness of the objective to the object, be
resorted to.

New hind of Achromatic Condenser suggested.

A larger, thicker, similarly bevelled disk, with the bevels
on opposite sides of the plate glass, and their lines of inclina-
tion coincident, would probably serve as an efficient achromatic
condenser of parallelrays. By attaching centrally, on the side
opposite the bevel, achromatic lenses of proper size, or a good
doublet combination, a most valuable form of achromatic con-
denser would I think be produced, useful for general micro-
scopic illumination. I have not yet put the plan in practice.
J. L. Rippert.—Silliman’s Journal.

© *2ao)

PROCEEDINGS OF SOCIETIES.

ZOOLOGICAL SOCIETY.

On the Structure of Echinococcus Veterinorum. By Tuomas H.
Houxtey, F.RS.

December 14th, 1852.—The author described the structure of
some large Echinococcus cysts with which the liver of a Zebra be-
longing to the Zoological Society was infested. ‘The animal met
with its death accidentally, having always appeared to be in good
health and condition, though the cysts were very large and nume-
rous, occupying a great portion of the substance of the liver.

The contents of the large cysts were free Echinococci and
secondary Echinococcus cysts, contained in a clear fluid. The
former were alive, and exhibited distinct, contractile motions.
Attention was drawn to two important points in their structure,
firstly, that the well known oval corpuscles were not calcareous,
inasmuch as they were rapidly dissolved by acetic acid without effer-
vescence, and were considerably acted upon by strong ammonia.
The author supposed that they were albuminous, and that, both in
these and the Teenie, the conversion into calcareous substance is
an effect of degradation ; and he pointed out their relations with
the solid bodies in the integument of the Turbellaria, and with the
so-called thread-cells of these and the Polypes. Secondly, that the
peculiar wavy cilia, characteristic of a water vascular system, could
be seen iz motion in the living EKehinococci. The cilia were de-
scribed by Lebert in 18438, but the discovery seems to have been
forgotten ; it is, however, a point of great importance now that the
existence of similar cilia in a definite water vascular system has
been demonstrated in the other Cestoid worms.

The proper wall of the cyst (as distinguished from the laminated
capsule) was traversed by a network of anastomosing vessels, to the
points of union of which the fixed Eehinococci were attached, the
cavity of the pedicle of the latter appearing to be continuous with
that of the vessels. It is in the cavity of the pedicle that Virchow
observed cilia. The secondary cysts varied in size from 1-100th to
1-30th of an inch. The contained Hchinococci were always of
about the same size, and all the smaller secondary cysts possessed
from one to four Hehinococeus heads attached to their outer sur-
face. The wall of the secondary cysts contains vessels like those of
the primary one. In the larger cysts the external heads were
found gradually disappearing, until they were quite smooth exter-
nally. When the secondary cysts were burst, their membrane con-
tinued to connect the heads, and formed the pedicle described by
various authors. The formation of the secondary cysts takes place
thus :— Echinococcus heads are formed over the whole inner surface

240 PROCEEDINGS OF SOCIETIES.

of the cyst ; this then becomes raised up at one spot by the develop-
ment of Echinococcus heads, outside it also, and, gradually project-
ing inwards, and acquiring a narrower and narrower pedicle, it
eventually falls into the cavity of the cyst as a free secondary cyst.
The external heads of the secondary cyst (internal of the primary
cyst) then gradually disappear; the internal ones (external of the
primary cyst) remaining entire and in a normal state. The process
is not essentially different from the ordinary germination of a Tenia
ovr Cysticercus.

The author then endeavoured to show that the Echinococcus
is nothing but the ‘ Scolex-form,” to use Van Beneden’s term, of
a Tenia, retracted within itself, then greatly dilated and deve-
loping Echinococcus heads from its inner and outer surfaces, which
are, however, like those of a serous sac, in reality both outer. It is
the extreme result of modifications similar to those already under-
gone by the Jenioid type in Cenurus and Cysticercus. The
conclusion thus drawn ou anatomical grounds is strikingly confirmed
by the result of the recent experiments of Von Siebold, who fed
young puppies with milk containing Echinococct, and, after a short
time, discovered Teenie in their intestines.

The author then, in speaking of the literature of the subject,
showed that the true nature of the Echinococci was fully under-
stood by Goeze in 1782.

The paper was illustrated by numerous drawings.

Royau Society.

Thursday, March 17, 1853.—Two papers by Dr. Martin Barry
were read; one on the subject of the ultimate structure of the mus-
cular fibre, and of other tissues in animals and plants. The second
on the occurrence of spermatozoa in the interior of the mammalian
ovum. Dr. Barry’s mode of viewing these subjects, but particu-
larly, perhaps, the former, is doubtless well known to all our
readers who may be interested in them, and neither paper presented
anything at all novel or interesting, as they were, in fact, merely
repetitions of the views first broached by Dr. Barry ten or eleven
years ago; and an attempted vindication of them against the
combined opinions of nearly all observers since that time. With
respect to the former of these subjects, the only modification the
author’s views have lately undergone consists in this,—that whereas
formerly the mystical double spirals perversely twisted themselves
in opposite directions, they are now harmoniously contorted in the
same.

Had it not therefore been partly from the circumstance of these
papers being read at the Royal Society, whence they might be sup-
posed to derive some extrinsic claim to attention, we should hardly
have thought it worth while further to advert to them, or rather to
the former of them,—-but on this account, and also because Dr.

PROCEEDINGS OF SOCIETIES. 241

Barry’s views have not long since been again produced under the
respectable auspices of Purkinjé, and in the pages of Miiller’s
Archiv. on the Continent, and in one of our most scientific
periodicals in this country,—we have thought it right to say a few
words on the matter. It is needless to enter into any discussion
with respect to the supposed facts adduced by Dr. Barry—for the
question, as one of fact, really admits of no discussion, and with
respect to the worth of the speculations, founded upon these facts, it
may suffice to observe that when Dr. Barry’s views regarding fibre,
contained in his paper in the Philosophical Transactions for 1842,
were first promulgated, they met with the most direct contradiction
from nearly every competent microscopic observer—at that time,
however, not a numerous class, and that, in the interval which has
since elapsed—and the ten years have produced a host of most com-
petent histologists—they have found no support, or scarcely any,
from any independent quarter, but, on the contrary, have almost
invariably, when noticed at all, been described as ‘‘ mythical and
fantastical.” The conversion or rather perversion of the venerable
Purkinjé to these views seems to have taken place under the direct
inspiration of Dr. Barry himself, and probably from examination of
his preparations. Dr. Barry, it is true, also claims the support of
Professor Agardh, given in his work on the structure of the cell-
wall in certain Algze; but it would be easy to show that Agardh’s
spiral structure, which moreover really relates only to the secondary
deposits in the wall, has little or no connexion with the mythical
double spirals of Dr. M. Barry. And we faney that Professor
Agardh would hardly deem it a compliment were he supposed to
entertain the notion that the nucleus of a cell “ resembles a ball of
twine, which it gives off to weave the cell-wall !”—With reference
to which we should be curious to see Dr. Barry’s explanation of the
formation of the cellulose wall around the primordial utricle in
Hydrodictyon, for instance, when no nucleus, in the common accep-
tation of the term, exists at any time,—that is, no nucleus distin-
guishable from the rest of the primordial utricle.

In his paper Dr. Barry also quotes Dr. Allen Thompson as a
believer in his views with respect to muscle. We have no infor-
mation on the subject, but perhaps Dr. Allen Thompson may have
since seen reason to doubt part at least of the premises upon which
he was led to fall into Dr. Barry’s views. His very high and
deserved authority in questions of this kind would, at all events,
render the knowledge of his present opinions most satisfactory.

With respect to the second paper, which consisted chiefly of a
reclamation of Dr. Barry’s priority in the discovery of the entry of
the spermatozoa into the ovum, elicited apparently by some expres-
sions in Dr. Nelson’s most valuable paper on Ascaris mystax it
is unnecessary here to say anything.

242 PROCEEDINGS OF SOCIETIES.

MicroscoPIcaL Society.

GrorGE Jackson, Esq., President, in the Chair.

March 23, 1853.—A paper, by Dr. William Gregory, F.R.S.E.,
Professor of Chemistry in the University of Edinburgh, entitled
‘ Notice of a Diatomaceous Earth found in the Island of Mull,’ was
read. The author commenced by stating that this earth was disco-
vered about two years ago by the Duke of Argyle, 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, and the sea. It is extremely rich in Diatomaceous
remains, containing (according to a synopsis sent with the paper)
various species of the genera Pinnularia Navicula, Gomphonema
Amphora Stauroneis, Cocconeis, Surirella Cymbella Himantidium,
Tabellaria Epithemia, Eunotia Cymatopleura, Synedra Fragilaria
and Orthosira. Those most remarkable for their abundance are the
genera Pinnularia Navicula and Stauroneis, and many of the species
of these and of the other genera are of great rarity. After giving
the chemical analysis, the Professor concluded by stating that the
Mull deposit appears to him to be richer in Diatomaceous species,
and perhaps in genera, than any other known deposit, there being
at least 60 species and 16 genera enumerated as having been found
in it. A portion of the earth and some slides containing specimens
accompany the paper.

( 243)

OBITUARY.

It is with the deepest feelings of regret we have to record the
unexpected death of Dr. Jonathan Pereira, F.R.S., F.L.S., &e., at
the age of 49, whilst in the prime of life and mental vigour. A
few weeks previous to this occurrence, he had been to consult Pro-
fessor Quekett on a scientific question; and whilst descending a
staircase leading to the Hunterian Museum, made a false step, fell,
and ruptured the rectus femoris muscle of both legs. In all pro-
bability, at the same time, some internal injury was sustained by the
heart or larger vessels, but as only local inconvenience was experi-
enced no danger was apprehended ; but whilst getting into bed on
the 20th of January, he felt a violent throb in the region of the
heart, when he became fully aware that a speedy termination to his
life was at hand, and this impression was verified within twenty
minutes after. He was a man of portly bearing, with pleasing
expression of countenance and great frankness of manner. Few
men were possessed of such general and sound knowledge of subjects
connected with his profession, and with so little affectation. He
was an excellent observer in pharmaceutical microscopy and
chemistry, and had a keen eye for what was practical ; his literary
judgment was very sound. He was author of ‘ Elements of Materia
Medica and Therapeutics,’ a work of universal reputation; the con-
cluding portion of the third edition he was actively engaged on up
to the time of his death. He also wrote ‘A Treatise on Food and
Diet ;’ ‘ Selecta e Prescriptis ;> and ‘ Lectures on Polarised Light,’
the best familiar exposition of that abstruse subject in our language.
He also contributed numerous articles to societies, journals, reviews,
&e. By his labours he rescued therapeutics from the chaos of
hypothesis and absurdity in which it was formerly involved, and
established it on a firm scientific basis. His death has left a void
amongst European pharmaceutists which will not be readily filled.
As a lecturer, he secured the attention of his class by an earnestness
of purpose, aptness of experimental illustration, and the practical
bearing of his remarks. He was a real friend to the student, to
whom he was ever most liberal in affording assistance, often devoting
valuable time in making him thoroughly acquainted with the subject
of his studies. Dr. Pereira was, at the commencement of his
medical career, apprenticed to a general practitioner, attended the
Aldersgate Dispensary, became its apothecary, and lectured on
Chemistry and Materia Medica. He afterwards became lecturer
on these subjects at the Aldersgate School of Medicine, where his
lectures attracted many students from the City hospitals. He
subsequently lectured at the London Hospital, till about six years
since. In 1840 he obtained the degree of M.D. Erlangen, and

244 OBITUARY.

became a licentiate of the London College of Physicians, and was
elected a fellow of that body in 1845. In 1841 he was appointed
Physician to the London Hospital, which post he occupied up to the
time of his death. He also lectured at the Pharmaceutical Society,
and was Examiner on Materia Medica in the University of London.
Though of good and affluent family, from reverses suffered by his
father through unfortunate mercantile speculations he was obliged
to make his way through the world unassisted, and he attained his
high position in the profession entirely through his own industry
and perseverance. He was a liberal advocate of popular education,
and frequently lent his aid at our scientific institutions. He loved
science for its own sake, and his name will ever be associated with
those departments to which he devoted his labours; whilst those
who were personally acquainted with him will long honour his
memory.

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DESCRIPTION OF PLATE III.

The letters refer throughout to the same or corresponding parts.

a, The Mucous Membrane of the mouth.

b. The Lip.

ce. The Alveolus.

d. The Pulp.

e. The Dentine.

f. The Enamel.

g. The Basement Membrane of the Pulp.

g}. Nasmyth’s Membrane especially.

h. The “* Enamel-organ ” or Epithelium of the Capsule.

z. The Basement Membrane of the Capsule, with its subjacent con-
densed tunic. Hunter’s inner, vascular, capsule.

k. The loose submucous cellular Tunic. Hunter’s outer, non-vascular,
capsule.

Fig. 1. Diagrammatic section of the inner incisor of the upper jaw
of a Seven-months Fetus. The loose enamel organ is indicated by * * * *,

Fig. 2. A cusp of the posterior molar, upper jaw of the same. The inner
outline represents it before the addition of acetic. acid—the outer after-
wards, when Nasmyth’s membrane is seen raised up into large folds.

Fig. 3. Edge of an incisor pulp—retaining its cap—not far from the
lower edge of the dentine, which was about 1-1600th of an inch thick.

Fig. 4. Edge of the pulp of a molar cusp, showing the first rudiment of
the dentine, commencing in a perfectly transparent layer between the
‘nuclei ” of the pulp and the membrana preformativa.

Fig. 5. Surface of this dentine, where it had attained a thickness of
1-2500th of an inch, before which the little cavities, if present, were not
visible.

Fig. 6. Nasmyth’s membrane detached from the subjacent enamel by
_ acetic acid.

Fig. 7. The “stellate-cells” of the human “ enamel-organ.”

Fig. 8. Tooth of the Frog, acted on by dilute hydrochloric acid, so as to
dissolve the enamel and free Nasmyth’s membrane. ‘The structure of the
dentine is rendered indistinct. At the base Nasmyth’s membrane is con-
tinued over the bony substance at z, in which the nuclei of the lacune
are visible. ;

Fig. 9. Extremity of the tooth of a Mackarel, acted on by hydrochloric
acid so as to dissolve the enamel. Nasmyth’s membrane is rendered
obvious, but is burst on the left-hand edge.

Fig. 10. Tooth-sac of a Mackarel, 1-50th of an inch long, extracted
from its alveolus. Its close resemblance to a hair-sac is very striking.

Fig. 11. Diagrammatic section of the dental follicles of a Skate, to show
the union of the upper and lower folds of the ‘‘ dental groove.”

Fig. 12. Extremity of a dermic, tooth-like spine, from the upper
surface of the head in the Skate, acted on by hydrochloric acid, which has
removed the layer of enamel,

VOL. I. Ss

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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.
8. Highley’s papers on Photography.
Fig.
1. Spiracle and Trachez of the Silkworm, magnified 60 diameters, exhi-
biting the elastic spiral fibre between the layers of the air vessels.
2. Proboscis of the Fly, magnified 180 diameters, showing the divided
absorbent tubes.

DESCRIPTION OF PLATE VIII.

On the Starch-granule, by Gi Busk, Esq.
oa 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 (seulus
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. :

2.) Filaments of Mesocarpus scalaris, Hass., var. 8, in conjugation, and

3.{ containing Asteridia.

4. Filament of Zygnema quadratum, Hass., in conjugation.

5. Filament of the same containing an Asteridium, 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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ORIGINAL COMMUNICATIONS.

On the genus Triceratium, with Descriptions and Figures of the
Species. By T. Bricutwett, F.LS.

Tue genus Triceratium, with several other genera of Diato-
mace, was established by Ehrenberg in a Memoir com-
municated by him to the Berlin Academy in 1839-1840.*
He founded it upon two species, described and figured in
the Memoir, 7. favus and T. striolatum, the former of which
is commonly taken as the type of the genus.

Several new species were afterwards described by Ehren-
berg in the monthly reports of the Berlin Academy, most, or
all of which, are given in Pritchard’s ‘ History of Infusorial
Animalcules,’ ed. 1852, pp. 448, 449, and in Kutzing’s
‘ Species Algarum,’ 1849, pp, 140, 141, but no figures have
been given of these species. Professor Bailey, of New York,
has described and figured one or two species discovered by
him.

We purpose, in the present memoir, to give descriptions
and figures of the known species, and to add some others
which have hitherto been unnoticed.

The Triceratia are all marine. We have detected nearly
all the recent species described in this memoir in material
obtained from the surface of the large sea-shells of the genera
Hippopus and Haliotis, before they have been cleaned. Many
of them, in this state, are covered with small zoophytes,
minute alge, and other parasites, and by a careful examina-
tion of these, Triceratia and other Diatomacee have been
obtained.

I have been indebted for a supply of one new and in-
teresting species, collected by Dr. Sutherland in the Arctic
Regions, to Dr. Baird of the British Museum. It is noticed
as ‘ T. striolatum, Ebr,’ in the appendix to Dr. Sutherland’s
‘ Journal of his Voyage in Baffin’s Bay and Barrow’s Straits,’
1850-1851, vol. ii. pp. exev-cxcix. ‘ Diatomacee.’ Having,
by the means above mentioned, obtained a good supply of
T. striolatum, and finding it to be clearly distinct from the
arctic one, | have named the latter 7. arcticum. Dr. Suther-

* Uber noch jetzt zahlreich lebende Thierarten der Kreidebildung und
den Organismus der Polythalamien. Von H™ Ehrenberg. Abhandlungen
der Koniglichen Akademie der Wissenschaften zu Berlin, 1839, p. 81.

VOL. I. Ss

246 ON THE GENUS TRICERATIUM.

land has given the following note with this species—“ Taken
from a depth of fifteen fathoms, shingly bottom, calcareous
district. Temperature of the water 31°.8; covered with
ice for nine months of every year. Union Bay, Beechey
Island, lat. 74° 43’; long. 92° W. September 4th, 1850.”

The frustules of this species were found in a mass un-
mixed with any other Diatomacez, and very much broken.
Many of the perfect frustules have the endochrome in them,
and when examined as first received, had very much the
appearance of being attached to a minute alga found among
them. This is, I believe, the only instance in which a large
number of living frustules of Triceratia have been found
isolated, and almost compacted together. Among the Dia-
tomacee collected by Dr. Sutherland in other parts of the
Arctic Seas, I have found a few frustules of ZT. arcticum, but
these occur, as do most of the other species, sparingly. I
have not been able to detect among all the specimens of
T. arcticum, furnished me, a single one, in which the fissi-
parous division appears to have commenced ; all the speci-
mens are, however, nearly equal in size, and agree in form
and structure, not presenting any of the variations which I
have noticed in J. striolatum, and in one other species as
hereafter mentioned.

Ehrenberg has given elaborate figures of the end and front
view of JT. striolatum, in the memoir above mentioned, but
he has not noticed any varieties of this, or, I believe, any
other species.

The general form of T. striolatum, on an end view, is
triangular, but I have found among the frustules obtained,
from the shells above mentioned, several specimens of a
pentagonal form, and having the appearance of being com-
posed of a number of pentagonal plates united together.
The colour and sculpture of these five-sided frustules is
precisely the same as that of the triangular ones. I have
also detected another variety of a cubical form, presenting
nearly a perfect square on the end view, and agreeing in
colour and sculpture with the triangular specimens. I have
not met with variations of this kind in any other species
except in TJ. scitulum, mihi, a small species in which the sur-
face is marked with large hexagonal cells, and in this species
I have detected a variety with four concave sides on an end
view, of which I have given a figure. Among the specimens
of T. favus, obtained from Thames mud, I have found one
presenting a very remarkable singularity. A semi-circular
arch is hollowed out of the centre of the end walls, having
a regular arched rim of square cells around it, resembling the

ON THE GENUS TRICERATIUM. 247

key-stones of a bridge, and leading to the conclusion that the
frustule, in its formation, meeting with some impediment,
had formed its walls around it.

These variations in form appear to me to confirm the view
now generally taken of the vegetable character of the Diato-
macee, while, on the other hand, they are in opposition to
the general law regulating the multiplication of the species.
Such forms could not proceed from a spontaneous longi-
tudinal division, in which each half produced a counterpart
of itself. ‘They are perhaps the result of that specific mode
of reproduction to which Mr. Smith has alluded in his
valuable papers on the Diatomacez, in the ‘Annals of
Natural History’ (series 2nd, vol. ix. p. 5). In this mode
of reproduction it is quite possible that abnormal variations
of form may take place.

For some excellent observations on the structure, mode of
growth, and general physiology of the Diatomacee, I beg to
refer the reader to the above-mentioned paper by Mr. Smith,
and particularly to that contained in the ‘ Annals,’ series 2nd,
vol. vii. pp. 1-5, and also to his Introduction to his most
useful ‘Synopsis of the British Diatomacez,’ the first volume
of which has been recently published.

Nearly one-half of the described species of Diatomacez
are fossil, the greater number being found in the Bermudas.
Several of the fossil forms are also found among the living
species. One of the difficulties attending the study of this
genus, and the determination, especially in the fossil forms,
of the species, arises from the difficulty of obtaining perfect
frustules, and examining them in their front aspect. The
imperfect frustules present only the end or triangular wall,
from which alone no perfectly satisfactory specific character
can be obtained. For this reason several of the species here
described and figured must be adopted only provisionally, 7. e.
till perfect frustules can be examined.

Many of the species also vary extremely in size. I have
observed this to be the case with nearly all the species of
which I have had an opportunity of obtaining many speci-
mens. In JZ’. striolatum and T. alternans, and in the latter
both in the recent and fossil specimens, the variations in
size are such as force one to the conclusion that they have
been formed by conjugation of frustules, or some mode of
reproduction varying from that of self-division. In the out-
line figures of varieties of J. striolatum (Pl. 1V., fig. 11),
will be found two, in which small frustules are adhering to
larger ones, as if they were budding or growing from them ;
this whole group were gathered from a shell of H/ippopus

s

248 ON THE GENUS TRICERATIUM.

maculatus, and are figured as they appeared, lying in a watch-
glass, with a little water over them.

The species of the genus Triceratium may, for the most part,
be recognised by the triangular form they present, on an end
view of a frustules. The “normal form of the frustule may be
represented by a vertical section of a triangular prism. — If the
frustule be placed upon one of its flat sides, we look down
upon its ridge and obtain a front view of its two other sloping
sides. If it bé placed upon one of its ridges, we have a front
view of one of its flat sides, generally broader than long, and
of its smooth or transparent suture, or connecting membrane.
If the frustule be progressing towards self-division, it is then
often considerably longer than broad, and when nearly matured
for separation, presents the appearance of a double frustule.

A simple frustule, when dissected or broken up, consists of
two triangular plates or walls of silex, forming the ends, and
of three oblong rectangular pieces or bands, forming the three
sides; the laites usually dividing themselves into several
elongated paralleliform pieces. These siliceous plates them-
selves are formed of several distinct layers of silex, dividing,
like the thin divisions of talc, and are frequently found of such
exquisite delicacy as to be difficult of detection.

Synopsis of the Species.

Section I.— Sides concave with the angles protruded. Valvular

cells minute.

1. TY. Solennoceros, Ehr. Sides deeply concave. Angles ex-
tended into long arms rounded off at the ends. Cells radiating in
straight lines to the extremity of the arms. Diam. 1-276th.

Fossil, in Bermuda earth. Perfect specimens of this singular and
beautiful species are rarely found. -Ehr. describes the arms as
tubular.

Kutzing, Species Algarum, p. 140.

Plate IV., fig. 1.

2. T. brachiolatum, mihi. Sides concave. The angles extended
into short arms, rounded at the ends, which are perfectly smooth,
while the rest of the valve is covered with minute cells. Diam.
1-250th.

New Zealand. Recent; from the cleanings of shells and small
alge. Rare.

Plate IV., fig. 2.

N.B.—This species appears allied to 7. pileolus, Ehr.; but is
much larger, and probably distinct.

3. T. tridactylum, mihi. Sides concave. Angles carried out
into a distinct papilliform extremity. Surface of the valves covered
with minute cells. Diam. 1-31 8th.

Fossil, in Petersburg earth, N. A. Rare.

Plate LV., fig. 3.

ON THE GENUS TRICERATIUM. 249

Section II.—Sides straight, or somewhat convex.
a, Surface with large hexagonal cells.

* Angles spinose.

4. T. comtum, Ehr. Sides straight. Angles extended into a
short stout spine. Sides of the angles with a projecting fringe, the
fringe having a row of oval depressions. Surface covered with
large hexagonal cells. The edge of the fringe is sometimes broken
off, leaving the appearance of small spines. Diam. 1-218th.

Kutzing, S. A., p. 140.

From the cleanings of Tridacnide and other shells.

Plate IV., fig. 4.

5. T. muricatum, mihi. A minute species. Sides straight.
Angles ending in a stout spine. Front view nearly square, re-
sembling an Odontella or Zygoceros. Diam. 1-583rd.

From the cleanings of Tridacnide and other shells.

Plate IV., fig. 5, a, a, front view ; 6, end view.

6. T. spinosum, Bailey. Sides furnished with 4 lateral sete.

Kutzing, S. A., p. 141.

In North America; a doubtful species. No figure has been
given of it, and I have not seen a specimen.

* * Angles not spinose.

7. T. favus,Ehr. Angles having an obtuse projection. Cells
on the surface large, and the hexagonal figure of them well defined.

Kutzing, S. A., p. 140. Diam. 1-200th to 1-150th.

Smith’s ‘ Brit. Diatomacee,’ vol. i., p. 26; plate v. 44, end
view ; and supp., plate xxx. 44, front view.

Thames mud, at the junction of the Yare and Waveney, near
Yarmouth. This species appears pretty generally distributed.
I have found it on shells, from various regions, and fossil in
Petersburg earth, N. A.

Plate IV., fig.6. This figure presents the remarkable formation
noticed before.

8. T. megastomum, Ehr. Sides straight. The hexangular cells
smaller and more delicate than in T. favus. Diam. 1-350th to
1-175th.

Kutzing, S. A., p. 140.

Allied to T. favus; but distinguished from it by its smaller size,
more delicate structure, and sharp triangular form.

Found in Ichaboe and other guano, and among the cleanings

and small alge from foreign shells, varying much in size.
Plate IV., fig. 7.

9. T. grande, mihi. The largest and stoutest species of this
genus. Sides convex. Angles attenuated, obtuse. Hexagonal
cells numerous.

Found on Tridacnide and other shells from the Indian Seas, not
unfrequent. Diam. 1-100th.

Plate IV., fig. 8.

250 ON THE GENUS TRICERATIUM.

Ehrenberg has described a large species ( 7. ocellatum) from the
Indian Seas. See Kutzing, $8. A., 141; but his description differs
altogether from the present one.

10. 7. scitulum, mihi. A small species, but varying in size; on
some of the frustules I have reckoned on an end view, about 45
cells only ; very slightly convex on thesides. Angles open. Diam.
1-350th.

From the cleanings of shells from the Indian Ocean.

Plate IV., fig. 9; a, end view.

Var. 8. Having four concave sides. I have detected this
curious variety on several occasions.

b. Cells very small.

11. T. striolatum, Ehr. Frustule on a front view longer than
broad with the ends deeply concave, transparent; colour, pale
brown. The whoie, under a high magnifying power, delicately
marked with minute cells. Diam, 1-290th.

Kutzing, S. A., p. 140.

Var. £. Frustule pentagonal; end view quinquangular; each
angle concave.

Var. y. Frustule cubical; end view square.

Recent: found among the small Alge, &c., on Hippopus macu-
latus.

PlateIV., fig. 10. a, front view; 6,end view. Fig. ec, pentagonal
frustule ; d, square ditto; e e e e, various aspects of the frustules.

12. T. arcticum, mihi. Front view broader than jong, with the
ends straight ; clearly distinct from the last species. Diam. 1-250th.

Beechy Island, Arctic Regions, Dr. Sutherland: and sparingly
among Diatomacee from other parts of the Arctic Seas.

Plate I., fig. 11. a, front view; 6, end view.

13. T. condecorum, Ehr. Sides nearly straight, or slightly convex ;
angles slightly rounded off. On an end view the rows of the cells
diverge from the centre in elegant curved lines. Diam. 1-384th. _

Kutzing, S. A., p. 140.

Fossil in Bermuda earth.

Plate I., fig. 12.

14. T. undulatum, Ehr. Sides undulated; three or four undu-
lations on each side. Angles pointed. Cells radiating in lines from
the centre of the valve. Diam, 1-480th.

Kutzing, S. A., p. 140.

In all the specimens I have seen, the posterior plates of silex
project beyond the undulations of the front plate, giving this species
a unique aspect.

Fossil, in Bermuda earth.

Plate IV., fig. 13.

15. T. amblyoceros? Ehr. Sides convex; very slightly undu-
lated. Angles rounded off. Posterior plates not conspicuous.

ON THE GENUS TRICERATIUM. 251

Pritchard’s ‘ Infusoria,’ 1852, p. 448. Fossil, Richmond, Virginia.
Diam. 1-456th.
Plate IV., fig. 14.

16. T. membranaceum, mihi. Walls of the frustule extremely
delicate; sides convex. Angles attenuated, ending in minute
papillz. Frustule dotted over with very minute cells. Diam.
1-233rd.

From the Thames mud. Rare.

Plate IV., fig. 15.

17. JT. acutum, Ehr. Sides straight or slightly convex, and
drawn to a point more or less lengthened out. Diam. 1-720th.

Surface with irregular cells.

Kutzing, S. A., p. 140.

Plate L., fig. 16.

Fossil, in Bermuda earth; varying much in form.

18. T. reticulum, Ehr. A minute species. Sides straight. Cells
small and somewhat irregular. Front view twice as broad as long.
Suture narrow. Ends round, projecting, somewhat like a Bid-
dulphia. Diam. 1-388th.

Kutzing, S. A., p. 140.

Fossil, in Bermuda and Richmond earth, and recent from shell
cleanings and small alge.

Plate IV., fig. 17. a, end view ; 4, front view.

Section III.— Ends of the angles entirely rounded off.

19. T. Montereyti, mihi. Ends of the angles enlarged and bluntly
rounded off. Structure of the frustule stout. End wall elevated in
the centre of the triangle, with the cells in that part stouter, and
gradually diminishing in size to the sides and ends, where they
nearly disappear. Diam. 1-300th.

Fossil, in a stratum of earth occurring near the shore of Monterey
Bay, N. A., abounding in Diatomacee. Furnished by Mr. A. J.
Taylor, of Monterey.

Plate IV., fig. 18.

20. T. alternans, Bailey. Ends of the angles divided from the rest
of the valve by a transverse line. Cells circular. Diam. 1-500th.

Bailey’s ‘ Microscopical Observations made in S. Carolina,’ &e.,
p- 40; and ‘Soundings,’ fig. 55, 56. Smith’s ‘Synopsis Brit.
Diatom.,’ p. 26; plate v. 45; plate xxx. 45.

On the shores of the British Atlantic and Pacific Oceans.

Fossil in several of the Diatomaceous earths from North America
and from Monterey, and in Peruvian guano.

This well-defined species varies greatly in size, both in the recent
and fossil states.

Plate IV., fig. 19. a, front view; 5, end view.

21. T.obtusum, Ehr. Sides straight or somewhat concave. Ends
rounded off. Cells small; irregular. Diam. 1-700th.

252 ON CERTAIN APPEARANCES OCCURRING IN DENTINE.

Kutzing, S. A., p. 140.

Fossil, in Bermuda and Richmond earth. Recent in Thames mud.

Plate IV., fig. 20.

22. T. semicirculare, mihi. Ends rounded off, and one end so
much so, as to reduce the frustule to a semi-circular figure.

Fossil, in Bermuda earth, not uncommon, about the size of the
last species, but varying in breadth.

Plate 1V., fig. 21. A narrow variety.

In the preceding arrangement of species we have indi-
cated characters of division which must be received with
caution, It is remarkable how, in these minute and obscure
organisms, we find ourselves met with the same difficulties,
as to any positive laws governing the formation of any generic
types, as in the larger and more complex forms of animal and
vegetable life. It appears as if we could carry our real
knowledge little beyond that of species, and, when we attempt
to define kinds and groups, we are met on every side by forms
which set at nought our definitions. With reference to the
species of the present genus, looking upon TJ’. favus, or mega-
stomum, as what we conceive to be the most perfect plan
(if any) on which this group is constructed, we find all the
species diverging from it, and carrying us to analogous forms
in other groups, or lost in them, Placing the perfect trian-
gular form of T. favus in the centre, we: may diverge im lines
to a circumference ending in one line, in the long-armed
T. Solennoceros ; itself nearly resembling Desmidium tridens, or
hexaceros, Ebr. ; in another line ending in a form resembling
Desmidium apiculosum; in another like Zygoceros rhombus,
especially in the front view; in another analogous to Amphi-
tetras antediluviana ; and in another to Campilodiscus cribrosus.

Norwich, June, 1853.

On certain Appearances occurring in Dentine, dependent on its
Mode of Calcification. By S. James A. Sarrer, M.B.,
F.LS., &c.

In KOlliker and Siebold’s Zeitschrift for 1850, Czermak pub-
lished a paper, on some points of the minute anatomy of the
teeth, whose importance has not, as it seems to me, been
sufficiently appreciated in this country. No abstract or trans-
lation of this paper has yet appeared in English, though the
interest and value of its contents probably equals any single
other that has appeared since the earlier writings of Purkinje
and Retzius.

ON CERTAIN APPEARANCES OCCURRING IN DENTINE. 253

Czermak, among other interesting matter, has been the first,
in this communication, to give a correct explanation of those
curious appearances of globular, conglomerate formations in
the substance of dentine, which have been so long an enigma
to some of our most indefatigable microscopists.

My object in the present communication has been partly to
give a summary and confirmation of Czermak’s paper, in
reference to certain points in the anatomy of dentine, and
partly to add some further observations of my own on the
same subject and in the same direction.

The peculiar markings on dentine, known as the “ Contour
lines,” and their appendages, the irregular patches of small
interspaces which limit the outer extremities of the contour
lines, have never received a rational explanation until the
publication of Czermak’s paper; and the latter appearances
especially have previously been the subjects of the most far-
fetched and untenable interpretations.

The peculiar patches of opaque interspaces, and the globular
masses of dentine which bound them, have been shown by
Czermak to be dependent on the mode in which the animal
material of dentine is calcified, and to a certain extent (though
I think not sufficiently) he attributes the contour lines to the
same cause. At all events they are obviously associated and
produced at the same time and under the same conditions of
nutrition, and must be considered together.

The appearances in question are found variously disposed in
different teeth and in different proportions in different speci-
mens. It may be remarked, however, that they are always most
conpicuous in those teeth whose enamel exhibits irregular de-
velopment ; and in making sections this may be remembered
for the purpose of selection. It will be found, moreover (as I
shall presently explain), that there is an obvious relation in
number and position existing between the contour markings
in the dentine and the grooves and irregularities on the
enamel—a fact which I have not seen mentioned, though I
believe it to be uniform. Czermak has, however, pointed out
another circumstance not previously described, by which this
condition may be recognized in the entire tooth—it is the
appearance of opaque white lines around the fang, forming white
rings: this can be best seen by moistening the tooth for a
minute and then holding it obliquely by the side of a bright
light. These rings, which vary in breadth from the 1-50th to
the 1-100th of an inch, are scattered in succession from the neck
to the apex of the fang: their white opacity contrasts remark-
ably with the darker, semi-clear, yellower intermediate por-
tions of the fang. These rings are, of course, abnormal : their

254 ON CERTAIN APPEARANCES OCCURRING IN DENTINE.

number varies : I have one tooth—an inferior canine—in which
there are thirteen rings strongly marked. Of the import of
these rings I will speak hereafter.

When, then, a well marked specimen (such as I have repre-
sented at Pl. V., fig. 1) is examined with a low power, the
arrangement of the contour markings* will be seen as follows:
—I would, however, first observe that the section should be
vertical, and of an entire tooth ; for if it be only of a portion of a
tooth, the relative position and direction of the markings in
the different parts of the organ cannot be seen, and these cir-
cumstances are of the first importance for comprehending the
import of the appearances in question.

The term “contour lines” originated with Professor Owen,
I believe, and implies the general similarity which these have
with the contour of the tooth. The contour of the two, how-
ever, is not identical, for the markings (in whatever part
examined) are more divergent than the outline of the tooth ;
and, passing from within outwards, abut in succession upon
the external surface of the dentine. In comparing the abso-
lute contour of any tooth, it will be found that the angle formed
by its sides is more acute at its summit, or the summit of any
particular cusp, than the contour markings within.

In viewing the specimen with transmitted light, it will be
seen thata series of dark opaque granular patches are arranged
immediately within the enamel and crusta petrosa in the outer
portions of the dentine. In the crown of the tooth they are
usually more distinct and definite than in the fang: they are
not continuous and do not form an uninterrupted layer, but are
separated from each other by intermediate portions of normal
and well-formed dentine. These patches are more or less
club-shaped, with the butt-end of the club towards the surface,
and the pointed or attenuated end stretching obliquely in-
wards and upwards towards the pulp cavity. These patches
are so irregularly defined that, unless viewed with very low
powers, their outline can scarcely be said to have any describ-
able shape. When, however, they are slightly magnified, or
seen without a microscope at all, they appear to be convex on
the outer and upper margin, and straight on the opposite side,
The upper margin and outer extremity are the darkest and
most defined ; the lower margin and inner extremity are Jagged
and ill-defined, The little elements of the patch are very
interrupted towards the inner extremity, but are scattered in a

* I employ the term “ contour markings” in preference to “ contour
lines,” because I intend thereby to include the opaque granular patch at
the outer limit of the lines, as well as the lines themselves—they are

essentially one in cause and meaning.

ON CERTAIN APPEARANCES OCCURRING IN DENTINE. 255

direction upwards and inwards and are lost. The contour
marking is then taken on bya dark linear streak, which passes
nearly in the same direction as the patch, witha slight curve,
towards the pulp cavity. The nature of this line does not
appear with low power ; it merely looks as an opaque streak,
more or less dark and defined. The patch, as I have observed,
is most marked near the surface of the tooth: the line, near
the pulp cavity ; and where they join they are both indistinct,
and sometimes not to be discerned. The relative direction of
the contour markings is curious and interesting, and the
examination of it in the different regions of the tooth is par-
ticularly important. Czermak does not notice this: indeed,
his figure, drawn to display the general arrangement, only
exhibits a very small portion of the tooth—not enough for the
purpose—and what is shown is faulty, and only approximative.

For the particular description of the course of a contour
marking, I will select the region just below the neck of the
tooth; they are there peculiarly indicative of their character
and meaning. In passing from the surface of the tooth to the
pulp cavity, the contour marking makes a double curve, like
the letter f, and precisely resembling the primary curves of
the dentinal tubes in that region. In passing from without
inwards the first curve presents a convexity outwards and
upwards, then bending in the opposite direction, the convexity
looks inwards and downwards, and as the line almost reaches
the cavity within, the curve still continuing, it passes almost
perpendicularly up the side of the pulp cavity, sometimes
apparently joining the line above it. Now it will be seen
that the curves of the contour marking not only resemble the
primary curves of the dentinal tubes in a general way, but
that they are exactly the same in amount at any particular
spot, and always opposite in direction: as the tubes bend in
one direction the contour markings bend in the opposite, so as
to cross the former almost strictly at right angles; and this
may be stated as a rule—that the curves of the contour mark-
ings are in proportion to the primary curves of the dentinal tubes
at any particular spot, and cross them at right angles. This
may be seen by reference to fig. 1. In the crown and fang
the contour markings are simpler and less curved. In the
crown they are more horizontal and, passing above the pulp
cavity, meet over its summit: here the markings are very
short. In the fang they are almost vertical, and nearly
parallel with the inner and outer surface of the dentine. The
lower ones are usually very ill marked, and though they can
be traced for a long distance up the fang, as they slowly
approach the pulp cavity, they are indistinct and interrupted.

256 ON CERTAIN APPEARANCES OCCURRING IN DENTINE.

Contour markings vary in intensity and number: they are
most abundant in the root and most marked in the crown.
In the root, though very numerous, they are often scarcely
visible. In the crown, when the line is well marked, it is
always bounded externally by the opaque patch ; but between
these there are frequently others less marked—in such in-
stances, lines without patches at their extremities.

In teeth, with more than one cusp, the upper contour mark-
ings are confined to their own cusps, and their extremities abut
against the sides of those cusps; but the succeeding ones join
the markings of the contiguous cusps.

The contour markings are also well seen in a transverse
section of a tooth, especially about the neck. Here they are
represented by a series of concentric rings—a_ horizontal
section cutting the successive markings at different distances
from the pulp cavity. In this view Czermak likens them, not
inaptly, to the year-rings in wood.

I would here observe that the contour markings are dark
by transmitted light, and opaque white by reflected. When
mounted in Canada balsam, with continued heat, so as to allow
the specimen to soak in the fluid resin for some time before
it cools, or when mounted in some liquid, the reverse is the
case. The same also happens when decalcified specimens
are mounted wet. It is the white opacity of the extremity of
the contour markings that produces the appearance of rings
on a tooth fang, already referred to.

Decalcified specimens exhibit further points concerming
the contour markings. In preparing these specimens | first
make the section accurately, as though for mounting in the
ordinary way; I then decalcify it by submersion in dilute
muriatic acid. It is impossible to make even and regular
sections by cutting the softened tooth, and I therefore always
make the section before I decalcify it.

A vertical section thus prepared will be seen to exhibit the
contour markings strongly. If such a specimen be hooked
about with needles, so as to break it up, it will be found to
tear in successive portions in the direction of the contour
markings, the tear usually being the line of the marking
itself. By this means the specimen may be broken up into a
series of triangular portions—the triangles being formed by
the external surface of the dentine and any two neighbouring
contour markings ; the base of such triangles is outwards, and
the attenuated apex is inwards, and drawn up the sides of the
pulp cavity. These triangular slips thus produced are the
intermediate portions of normal dentine, situated between the
contour marking. Even the well formed dentine tears readily,

ON CERTAIN APPEARANCES OCCURRING IN DENTINE. 257

but it is parallel with, and in the same direction, as the contour
markings. ‘Transverse sections decalcified break up into a
series of concentric rings, beautifully and exactly regular : it
is not easy to tear out complete rings, but they are partially
separable, and are indicated in great numbers; indeed their
number seems to be limited only by the mechanical means
employed to isolate them. Such a specimen is exhibited at
fig. 2. Now, the breaking up of a vertical section into
triangular imbricated slips, and of a transverse section into a
series of rings, is tantamount, in the entire tooth, to a stratified
or laminated arrangement : indeed, considering these circum-
stances, as they bear upon the solid tooth, they indicate its
composition (in one point of view) as a series of hollow cones
adapted one upon the other.

Czermak notices the stratification of the dentine, and speaks
of the strata being loosened from each other: he says, “I have
succeeded in breaking off whole layers of tooth-substance,
which had perfectly smooth surfaces.” He considers that the
splittings of the tooth-substance are by no means a resolution
of the structure into its original elementary parts. He further
says,—‘‘ The ground substance has certainly a stratified com-
position, but this is usually latent, as it were.” It is fair to
observe that the lamellation of dentine, as exhibited in de-
calcified teeth, was first pointed out by Dr. Sharpey,* in the
tooth of the Cachalot whale. It is most readily seen in the
teeth of large mammalia (elephant, hippopotamus, &c.), but
its import is better understood in smaller teeth, where its re-
lation to the entire organ can be contemplated at once.

I may here point out a fact which, if it have been noticed,
has, I believe, hitherto escaped recording ; at least it has never
been distinctly expressed. It is, that the contour markings,
as well as the fracture lines, which so readily occur in the in-
termediate normal dentine, and are parallel to them, exactly
correspond to the pulp surface in the progressive formation
of the dentine—are identical in fact with the junction line of
the pulp and internal dentine surface at any particular time
of growth. In contrasting such a section as is exhibited at
fig. 1, with a series of one-cusped teeth in different stages of
advancement, this will easily be recognised: the portions of
dentine seen between the contour markings in viewing the
tooth from above downwards are, as it were, the successive
increments by which the organ is built up, and by which the
original expanded cap of dentine as it first appears, is con-
verted into an elongated cylinder with a tube up the centre.

* Quain and Sharpey’s Anatomy, p. 978,

258 ON CERTAIN APPEARANCES OCCURRING IN DENTINE.

I have dwelt thus much upon this point, as I have presently
to show how the contour marking is produced by a condition
common to the entire growing surface of the dentine at one
time.

Having said thus much of the general arrangement of the
contour markings, I will describe their anatomy as displayed
by higher microscopical scrutiny.

Two hundred diameters will suffice for the magnifying
power. When the patches are thus examined they are seen
to consist of globular masses of dentine more or less isolated
by interspaces, as they are less or more confluent one with an-
other. The dentine globules (‘‘ tooth-substance-balls,” as Czer-
mak calls them) are spheres, hemispheres, or partial spheres,
usually of normal dentine, and traversed in the usual way by
dentinal tubes. Their size varies immensely—from 1-400th,
1-300th, or even 1-250th of an inch, down to particles of
granular dimensions ; even 1-10,000th of an inch in diameter ;
indeed there seems no limit to their minuteness. When
cleanly mounted the outline of the globules is beautifully
sharp. The interspaces between them vary in form according
to the number and size of the globules that bound them. In
contemplating a large interspace one sees the globules and
partial spheres bulging into it, some bright and clear, others
looming indistinctly out of focus. Sometimes the interspaces
are reduced to mere semi-lunar lines of extreme tenuity.
These appearances are represented in fig. 3. Dentine
globules are largest in the crown of the tooth, and smallest in
the fang, especially near the cemental surface: indeed, in the
latter situation, in passing from the surface towards the pulp
cayity they regularly enlarge, but while they increase in size
they become more fused together, the globules are less
spherical, and the interspaces proportionally smaller.

I would here remark that the interglobular spaces (as
ordinarly observed in teeth extracted, allowed to get dry,
and subsequently cut into sections) are ‘truly hollow and filled
with air. This Czermak has enforced.

The relation which the dentinal tubes have to the dentine
globules and the interglobular spaces, is interesting and re-
markable. The globules are permeated by tubes exactly as
the other dentine: the face of a large globule sometimes
exhibits as many as five or six tubes tray ersing it. Now, in
following an individual tube across a mass of globules, one
observes it follow a regular course, just as if there were no
interspaces: one follows the tube across one globule, then,
skipping the interspac e, one finds it crossing the next globule
in a line with its position in the first, naga so on. There

ON CERTAIN APPEARANCES OCCURRING IN DENTINE. 259

seems an evident continuity. In specimens, in whieh the in-
terglobular spaces have been filled with Canada balsam, I have
seen (as I have believed) the dentinal tubes collapsed upon
the sides of the interspace, establishing the continuity. Kol-
liker has seen more than this; for he says, that in decalcified
specimens the interglobular spaces are sometimes filled with a
soft substance, which is traversed by tubes, and “ these may be
entirely isolated like the dentinal tubes.” Though I have looked
for these I have not seen them, but of the fact I cannot doubt
when stated by such an authority, especially as I have observed
what amounts to the same in a different phase.

The linear portion of the contour marking is explained
in four ways :—First, by a series of secondary curves in suc-
cessive dentinal tubes ; secondly, by the dentinal tubes being
locally widened ; thirdly, by interglobular spaces. The two
first, though producing the same general appearance when
seen with low powers, are, I believe, essentially different from
the contour marking dependent on abnormal calcification.

The interglobular spaces, which form the contour line, are
usually a few scattered semilunar streaks, when seen with
high power: sometimes these become confluent, and they
then form a narrow linear interspace, not wider than a denti-
nal tube. This latter I have not seen described. Not un-
frequently, however, it is impossible to find any anatomical
change, even when examined with the highest power, in the
dentine that exhibits a contour opacity; and I can only
imagine that a difference in density of such a layer relative
to contiguous layers, probably dependent on its composition
in the amount of earthy and animal matter it contains respec-
tively, may possibly produce it. Such an explanation is quite
in keeping with the rationale of the other element of the con-
tour marking.

The explanation of globular dentine, and indeed of all the
circumstances of the contour markings, is to be sought, and is
to be obtained, by examination of the pulp, or inner surface
of the dentine, especially of growing dentine. This is the
great point of Czermak’s paper.

To obtain a specimen for examination, Czermak directs
that a tooth (not completely formed) should be split, and then
the section ground from without inwards until sufficiently
thin, the pulp surface never being allowed to touch the stone ;
the preparation is then to be mounted, with the inner, unrubbed
surface supine. The appearance of such a specimen is thus
graphically, and, as I can testify, most accurately described
by Czermak :—.

“The tooth-substance appears then on its inner surface, not as a sym-

260 ON CERTAIN APPEARANCES OCCURRING IN DENTINE.

metrical whole, but consisting of balls of various diameter, which are fused
together into a mass with one another in different degrees, and on which
the dentinal tubes, in contact with the germ cavity, are terminated. By
reflected light one perceives this stalactite-like condition of the inner sur-
face of the tooth-substance very distinctly, by means of the varied illumi-
nation of the globular elevations, and by the shadows which they cast.
Here one has evidently to do with a stage of development of the tooth-
substance, for the older the tooth is the less striking in general are these
conditions, and the more even is the surface of the wall of the germ-cavity.
In very old teeth considerable unevennesses again make their appearance ;
these, however, are not globular but have a cicatrized, distorted appear-
ance. It is best to make the preparation from a tooth, of which the root
is not perfectly completed. With such preparations one is readily con-
vinced that the ground substance of the last-formed layer of the tooth-
substance appears, at least partly, in the form of balls, which are fused
among one another and with the balls of the penultimate layers ; and one
also perceives that in general their diameter becomes less and less, some-
what in the form of a point, towards the periphery of the tooth-substanee.
The majority of these balls is pierced through by one or more tubes,
crosswise, from within outwards. Very frequently, however, they appear
homogeneous, and contain no tubes.”

I will only add, from my own observation, that the globular
surface is hardly so general as Czermak implies. Often one
sees a considerable area that is even and flat, and destitute of
globules. The large globules are always traversed with
tubes ; those not traversed by tubes are always small. The
globules, on the germ surface of secondary dentine, are small
and tubeless; they are often very minute,

I have found it much easier to obtain specimens than the
plan proposed by Czermak, by procuring a tooth of which
the fang is half grown, then introducing the point of a pen-
knife into its open extremity, and scraping the inner surface.
Small portions may be detached, which exhibit the globules
admirably.

Another method of obtaining specimens, which further
illustrate the internal surface of the dentine, is the following.
In rubbing down a section of a tooth, as the operator ap-
proaches the pulp cavity, the last film of dentine frequently
bulges into the unresisting cavity, and, instead of grinding up
into particles, comes away in a little sheet, a little film of
dentine parallel with the pulp-cavity’s surface, the innermost
layer, and the one last formed. This should be carefully pre-
served and mounted. On viewing such a specimen by trans-
mitted light, one sees the globules scattered about—some
isolated, others more or less confluent ; and between them a
pale, rather indefinite structure, uniting the whole into a
sheet.

Now, in Czermak’s specimen one sees only the stalactite-
like surface of the pulp cavity, and the prominent inner glo-

ON CERTAIN APPEARANCES OCCURRING IN DENTINE. 261

bules do not appear connected; whereas, in specimens ob-
tained as I have just described, they are seen to form part
only of the innermost layer of dentine. Upon close inspec-
tion, by transmitted light it is found that the globules are
composed of well-formed consistent dentine traversed by
patent tubes, the open extremities of which are presented to
the eye. The tissue between the globules has a somewhat
similar aspect, but the tubes appear shrivelled and collapsed,
or are not indicated (see fig. 4). The innermost layer of
secondary dentine, viewed under similar circumstances, pre-
sents the same general aspect: but the globules are tubeless,
and the intermediate tissue appears homogeneous (see fig. 5).

But the most instructive specimens are to be obtained from
the very thin cap of dentine found upon the foetal pulp. The
thin edge should be cut off, and examined on the inner sur-
face; it should be moist, and never allowed to get dry. In
such specimens the globules are very apparent, but, as Czer-
mak observes, they do not appear superficial but in the sub-
stance of the dentine. This he has not explained, but I have
observed that, by gradually depressing the focus of the micro-
scope, the first object that meets the eye is the ends of the
columnar pulp-cells adherent to the surface of the dentine.
As the focus is carried deeper, these appear more or less
fused together, and more remotely the dentine assumes a con-
sistent and definite structure. It is here, in the moist spe-
cimens, that the focus reaches the globules, and, consequently,
there is no superficial stalactite-like bulgings of globules: it
_is only in dry specimens that that is seen. Now, if such a
specimen be steeped in dilute muriatic acid so as to remove all
the earthy materials, the globules instantly vanish, and the den-
tine, where they were seen, assumes the same aspect as that where
they were not seen. No other change is produced. The exist-
ence of the globules, therefore, seems dependent upon the
presence of earthy material. This suggested to Czermak the
idea that the organic material of dentine is, during the cal-
cifying process, impregnated with earthy salts in globular
forms, and that, by a deeper degree of calcific impregnation,
the whole tissue is imbued with the hardening element, and
the globules are fused. Such a doctrine is capable of ex-
plaining all the circumstances of the case; and we have only
to imagine an arrest of calcification at the globular stage, over
the surface of the pulp as it exists at any one time, to explain
all the phenomena of the contour markings,

In teeth which have been allowed to get dry, one would
imagine that those portions of dentine which have calcified
would retain a consistent form, while the uncalcified animal

VOL, I. T

262 OBSERVATIONS ON THE

material would shrivel up: hence the stalactite-like appearance
of the pulp-cavity’s walls, and hence also the interglobular
spaces in a dried tooth. I have shown that, in the innermost
layer of dry dentine, the globules are held together by an
attenuated tissue, in which the ends of dentinal tubes are in-
dicated. Again, the contour lines, which exhibit no inter-
globular spaces, but which are continuous with imperfectly
calcified globular patches, may be imagined to be themselves
dependent on deficient lime impregnation. The integrity of
such deficiently-hardened dentine would be seriously inter-
fered -with by getting dry; hence, probably, one reason why
decalcified dentine so readily tears along these lines.

Now, the idea that the contour markings are produced by
an imperfect supply of calcarious material is consistent with
other collateral circumstances. Upon that idea one would
imagine that other tissues besides dentine, dependent for their
maturation on lime impregnation, and the other teeth, would
suffer at the same time; that is, believing the effect to be
produced by a general vice of nutrition: and such, indeed, is
the fact. The enamel almost always suffers at the precise
spot where the globular patch abuts upon the surface, rendering
it irregular and rocky; and it will constantly be found that
these appearances are observable on many teeth of the same
individual ; not at the same spot on all the teeth, but at places
corresponding with the different degrees of development which
the various teeth would have attained at one particular period.

Why the dentine should be thus aborted, so to speak, at
successive periods of its growth, and why during intermediate
intervals it should mature perfectly, are questions which can
only be explained by imaginary successive periodic condi-
tions of depressed and healthy nutrition in the individual
during the formation of such teeth.

Observations on the Muscular Tissue of the Skin. By JosEru
Lister, M.B. Lond. F.R.C.S.

Awmone the abundant new matter contained in those parts of
* Kélliker’s Microscopische Anatomie’ that are hitherto pub-
lished, there is perhaps nothing more striking than the
announcement that small bundles of unstriped muscle exist
in all parts of the dermis that are provided with hairs, con-
nected inferiorly with the hair-follicles, just below the seba-
ceous glands, and passing up obliquely towards the free
surface of the skin.

MUSCULAR TISSUE OF THE SKIN. 263

The effect of the contraction of such little muscles must
necessarily be to thrust up the hair-follicles and depress the
intermediate portions of skin; in other words, to produce
cutis anserina ; and thus this condition, previously quite un-
accounted for, received at the hands of Professor Kolliker a
simple and beautiful explanation.

In March of the present year (1853) I made an attempt to
verify this most interesting discovery; and although the
somewhat arduous duties of a resident office in University
College Hospital prevented me from making the investigation
as extensive as I could have wished, yet I found myself able
not only to verify, but in some slight degree to add to Kdlli-
ker’s observations. And as the main fact of the muscularity
of the skin had not previously, so far as | am aware, found
confirmation in this country, I have been induced to publish
my results in the hope that they may prove acceptable to the
microscopical anatomist.

Kolliker originally described* these muscles of the skin as
flat bundles of unstriped muscular tissue, from 1-120th of an
inch to 1-75th of an inch in breadth, of which there appeared
to be one or two in connexion with each hair-follicle : it seemed
probable to him that they arose from the superficial parts of the
corium, and he had clearly seen them passing obliquely down-
wards to their insertion into the hair-follicles, close behind
the sebaceous glands which they embraced. In his ‘ Hand-
buch der Gewebelehre,t published in 1852, he gives in the
text exactly the same account of these muscles, except that he
no longer expresses any doubt regarding their origin from the
superficial parts of the corium. He afterwards states in a
note that these muscles had been very recently seen by two
observers, Eylandt and Henle, both of whom, however, had
found them narrower than he. Eylandt, who named them
“arrectores pili,’ had never seen more than one bundle
connected with each hair-follicle, and had failed to detect
muscular tissue in the nipple and areola, and in the sub-
cutaneous cellular tissue of the scrotum, penis, and_peri-
neum, where Kdélliker had described it as existing. Henle
had traced the muscles to the most superficial parts of
the dermis, where they divided into numerous little bundles
1-3000 of an inch in diameter, which could be followed to
immediately beneath the epidermis ; he had also seen muscular
tissue in the nipple, areola, and the other parts where K@lli-
ker had described it, but, on the other hand, in the opinion
of Kolliker, he had gone too far, inasmuch as he described

* Vide Microscopische Anatomie, vol. ii. part i. p. 14.
¢ Vide Handbuch der Gewebelehre des Menschen, p. 82.

T2

264 OBSERVATIONS ON THE

bundles of plain muscular tissue as existing on the exterior
of the sudoriferous glands and blood-vessels of parts destitute
of hairs (such as the palm and sole). These Kolliker is
unable to discover, and he believes that Henle has been
misled by the use of boiled preparations, in which, as Henle
himself states, fine branches of nerves are liable to be mistaken
for muscle. Thus it appears that the confirmation furnished
by these two observers is by no means a very satisfactory one,
and that Henle, the only authority on whom we rest for the
fact of the muscles taking origin immediately beneath the
epidermis, cannot, in the opinion of Kolliker, be implicitly
relied on with reference to this investigation. It appears
remarkable that Eylandt should have failed to discover
muscular tissue in the scrotum, for the dartos was long
since proved to owe its contractility to unstriped muscle.
Of the parts in question I have examined only the areola
mammz, which, however, answered well to the description
given by Kolliker, who states* that the bundles of muscle are
there circularly disposed, forming a delicate layer in the deeper
parts of the corium, and encroaching slightly on the subcu-
taneous cellular tissue. On dissecting a portion of an areola
from the subcutaneous tissue towards the surface, I found on
reaching the deepest part of the dermis a delicate pale reddish-
yellow fasciculus circularly arranged ; and a portion of this,
teazed out with needles, and treated with acetic acid, presented
in a well-marked manner the nuclei of plain muscular tissue.
A camera-lucida sketch of a small portion is given on a re-
duced scale in Pl. VL., fig. 6.

In enumerating the parts where he has met with muscles
connected with the hairs, Kélliker does not mention the scalp,
probably because the density of the tissue of this part ren-
dered it unfit for investigation by the method in which he
prepared his objects, viz., isolating a hair follicle with its
sebaceous glands and treating it with acetic acid. Its very
firmness and consistence, however, make the scalp better
adapted for fine sections than any other part of the skin; and
as 1 succeeded better with sections than by the other method,
the scalp has received most of my attention. By compressing
a portion between two thin pieces of deal, and cutting off with a
sharp razor fine shavings of the wood and scalp together, mode-
rately thin slices may be obtained. Fig. 4 represents a perpen-
dicular section made in this way, and treated with acetic acid ;
the epithelium has become detached from the free surface a b;
bc is part of one of the muscles near its superficial attach-

* Vide Micr. Anat., vol. ii. part i. p. 14.

MUSCULAR TISSUE OF THE SKIN. 265

ment, and it illustrates pretty well the appearance presented
by them under a rather low power. They are distinguished
from the tissue around them by their transparent and soft
aspect, and by the abundant elongated nuclei scattered through
them. Under a higher power the characteristic ‘‘ rod-shaped”
nuclei become fully brought out, and no doubt remains as to
the nature of the tissue. A good example of nuclei so
magnified, derived from a muscle connected with a hair-
follicle of the pubes, is shown in fig. 5. It will be observed
in fig. 4, that the muscle has been traced to within a very
short distance of the surface, where the nuclei became
obscured by other tissues.

But I afterwards found that much better sections could
be obtained from dried specimens. A portion of shaved
scalp being placed between the two thin slips of deal, a
piece of string is tied round them so as to exercise a slight
degree of compression; the preparation is now laid aside
for about twenty-four hours, when it is found to have dried
to an almost horny condition. It then adheres firmly by
its lower surface to one of the slips, and thus it can be
held securely, while extremely thin and equable sections
are cut with great facility in any plane that may be desired.
These sections, when moistened with a drop of water and
treated with acetic acid, are as well suited for the investiga-
tion of the muscular tissue, as if they had not been dried.

Fig. 1 is slightly reduced from a camera lucida sketch*
of such a section, made in a plane perpendicular to the sur-
face of the scalp, and at the same time parallel to the sloping
hairs. I find that such a plane always contains the muscles in
their entire length, the reason of which will appear shortly. In
this figure d is the corneous, and e the mucous layer of the
epithelium; 0, b,.... are the hair-follicles with their con-
tained hairs, both have been more or less mutilated by the
process of section; the second hair from the right being a
short one, its bulb is seen: cc.... are the sebaceous
follicles, also more or less mutilated: a, a,....a, are the
muscles, which appear, under this very low power, merely as
transparent streaks, and require a higher power to make out
their tissue. The muscles are seen to arise in all cases from
the most superficial part of the corium, and to pass down
obliquely to their insertions into the hair follicles immediately
below the sebaceous glands. It will be remarked that the
muscles are here all on the same side of the respective hair-

* In all the sketches from which the figures that illustrate this paper
have been taken, I have used the camera lucida, which instrument has
the great advantage of ensuring correctness of proportions,

266 OBSERVATIONS ON THE

follicles, viz. on that side towards which the hair slopes: and
such I found in the examination of a large number of sections
to be always the case. This is an interesting fact, as such an
arrangement of the muscles is exactly that which is best
adapted for erecting as well as protruding the hairs, which
must be drawn by their contraction nearer to the perpendicu-
lar direction. That this erection as well as protrusion of the
hairs does occur, I have proved by artificially exciting the state
of cutis anserina upon my ownarm and leg. Tickling aneigh-
bouring part will often induce horripilation, and if the eye is
kept on an individual hair at this time, it is seen to rise
quickly as the skin becomes rough, and to fall again as the
horripilation subsides. I have never seen more than one
muscle to each hair-follicle in the scalp; and in order that a
single muscle may by its contraction simply erect a hair, it
must be placed in a plane perpendicular to the surface of
the skin and parallel to the hair; this explains the fact before
alluded to, that a section made in such a plane is sure to
contain the muscles in their entire length if at all, while
sections in other planes cut across either the muscles or the
hairs.

Fig. 2 represents the superficial attachments of the two
muscles a, and a, of fig. 1; a being the upper end of a,
and 6 that of a,; ¢ is the corneous, and d the mucous layer
of the epidermis ; the intervening tissue between the muscles
was omitted in the sketch to save time. 6 furnishes a good
example of the subdivision of a muscle into secondary bundles
near the surface, as observed by Henle, while in a the sub-
division, if it has occurred at all, is certainly not carried so
far: the muscle d ¢ in fig. 4 seems not to have undergone any
subdivision: in some cases a simple bifurcation of a muscle
near the surface is all that is seen: hence the splitting up of
the muscles into smaller bundles near their upper attachment
appears not to be a constant thing, and when it does occur
exists to a very variable degree in different muscles. Want
of room in the plate has rendered necessary so great a reduc-
tion of the scale* from the original drawing, as barely to
allow the nuclei of the muscles to be perceived ; by looking
closely, however, it may be seen that at e and f nuclei exist
immediately under the epithelium, and before introducing
them into the sketch, I ascertained, by a higher power,
that they were really of the same character as those in
other parts of the muscles, At g it was impossible to trace
the nuclei so far; if any existed here, they were obscured by

* Figs. 2, 3, and 4 have all been reduced one-half from the original
sketches,

MUSCULAR TISSUE OF THE SKIN. 267

the fibrous tissue of the scalp, which adheres to the muscles
throughout their whole length, but appears to form special
sheaths for the bundles of origin at the surface, and these
sheaths interfere considerably with the examination of the
muscular tissue enclosed by them. In some cases, however,
they seem to be prolonged beyond the point to which the
muscular tissue reaches, acting as tendons of attachment, and
this may perhaps be the case at g: I have seen one striking
instance of this mode of attachment, where a muscle having
divided into two portions at some depth below the surface, a
pretty long band extended like a cord to the surface from one
of the divisions, and acetic acid having been added, nothing
whatever but yellow elastic fibres could be seen in this band
(the white fibres had been of course gelatinised). As a
general rule, however, the muscular tissue extends to within a
very short distance of the epithelium, and often, as above
stated, can be detected immediately beneath it, as Henle has
represented.

In fig. 3 is shown the connexion of the muscle a,, of fig.
1, with its hair-follicle; so that were the muscle a of fig. 2
continued far enough downward, it would join with a of
fig. 3. The hair and its follicle are seen cut across very ob-
liquely: 6 is the hair, tilted somewhat out of its natural
position in the inner root-sheath c; d is the outer root-sheath
(corresponding to the mucous-layer of the epidermis), whose
outer cells are perpendicular to the hair-follicle ; e is the
** structureless layer” of the hair-follicle ; f is the circular
layer of KGlliker; g the external longitudinal layer with
which the muscle is seen to become blended. Several elon-
gated nuclei appeared at g,; whether these are derived from
the muscle, which is evidently inserted a good deal into the
part of the follicle that is hidden from view, or whether
they are only the elongated nuclei that occur in all parts
of the longitudinal layer of the follicle, is doubtful: their
well-marked elongated character inclined me rather to the
former opinion ; / is a part of one of the sebaceous follicles,
which appears to have no special connexion with the muscle
that simply passes close by it without embracing it, as Kol-
liker implies, or sending any muscular expansion over it ; and
the same occurs in all cases, so far as [ have seen; 7 is a
portion of the fibrous tissue of the dermis, showing its con-
nexion with the surface of the muscle.

Kolliker’s description of the muscles of the skin (see p.
263) does not quite accord with what I have seen in the scalp,
either as regards their shape or size. The muscles in this
part had not, in sections parallel to their course, the appear-

268 ON THE MUSCULAR TISSUE OF THE SKIN.

ance of flatness ; and by cutting slices in the way above indi-
cated, at right angles to their known direction, their transverse
sections were readily seen, and proved to be ‘often quite cir-
cular, sometimes somewhat elliptical or polygonal, showing
their form to be that of more or less rounded bundles. Their
average diameter is, according to my experience, 1-200th of an
inch, which is less than half the average of Kélliker’s mea-
ea but this discrepancy is probably due to difference
of situation in the parts observed, Kolliker not having ex-
amined the scalp: for one muscle: which I sketched from the
pubes was very nearly 1-100tk of an inch in diameter.

With regard to the statement of Henle, that muscular tissue
exists in parts destitute of hairs, I have searched with dili-
gence many good sections of both the palm and the sole,
without having been able to discover any evidence of it on the
exterior of either the sudoriferous glands or blood-vessels of
these parts. Ina section treated with acetic acid, the elon-
gated nuclei of the internal coat of a small blood-vessel some-
times give it an appearance that might at first sight be mis-
taken for that of unstriped muscle; but this is an error easily
avoided by care, and I cannot but agree with Kolliker in
thinking that, in some way or other, his boiled preparations
have led Henle into error. ]

In order to verify Koélliker’s statement* that no unstriped
muscle exists in connexion with the vibrisse of mammalia, I
examined the feelers of a cat. These large hairs extend far
down into the tissues beneath the skin, and have a more com-
plex muscular apparatus than the small hairs of the human
skin. Bundles of muscles extend from the lower part of the
gigantic hair-follicle obliquely upwards to the inferior aspect
of the skin, and, in addition to these, there is muscle sur-
rounding the large nerve that enters the base of each hair-
follicle. These muscles were all of the striped kind, but
extremely soft and extensile, and among the fibres were a
number of very elongated nuclei, but I saw no distinct evi-
dence of the admixture of unstriped muscle.

In conclusion, I may state that this investigation has proved
to me the general correctness of Kdélliker’s original observa-
tions, and also of the results of Henle’s further inquiry,
except in the case of the alleged muscularity of parts destitute
of hairs ; and I shall be happy if the little additional matter
communicated in this paper shall be found to bear as well
the scrutiny of others.

University College Hospital, June 1st, 1853.

* Vide Micr. Anat., vol. ii. part i. p. 15.

TRANSLATIONS.

Remarks on the Structure and Function of the Retina. By
H. Miter. From the Verhand. der Physical. Medicin.
Gesellschaft in Wurzburg. B. Il1., H. II1., p. 336. 1852.

Tue view respecting the physiological function of the various
layers of the retina arrived at by Professor Kolliker, from the
investigation of the human eye, and which he has detailed in a
previous paper in these Transactions, I have, also, been led to
adopt in the most essential points, from continued researches
respecting that membrane.

On the one hand, the difficulty, and almost the impossibility,
of maintaining that the expansion of the optic nerve is the
perceptive element for objective light becomes continually
more and more obvious; and, on the other, the mosaic-like
contrivance for the reception of impressions separated by
spaces, which was formerly generally assumed as a postulate,
although in vain sought for, in consequence of the altered
view respecting the structure of the retina, appears now to be
admitted ; particularly since it has been shown that the radial
fibres are continuous ezternally in “ cones” and “rods,” but
are internally in the closest contact with the expansion of the
optic nerve, and probably in part connected with it. The
circumstance, that such a radial arrangement of the retinal
elements occurs in all the vertebrate classes (vid. Zeitsch. f.
wiss. Zoologie, III., p. 234), notwithstanding all the divers
variations which otherwise exist in the condition of the indi-
vidual layers, confers an important significance upon this
arrangement. But in favour of the notion, that it is the
radially disposed elements, and not the horizontal fibres of the
optic nerve, which first perceive the objective light, I find,
besides the points adduced by Professor Kélliker, a weighty
argument in the peculiar structure of the retina in the Cepha-
lopoda, whose much developed eyes, of all the Invertebrata,
come nearest to those of the vertebrate class.

In the Cephalopoda the innermost layer of the retina consists
of elongated, slender, transparent cylinders, which are, in
many respects, similar to the “rods” of the vertebrata; and
like them densely crowded together, are disposed in the di-
rection of the radius of the whole eye. Behind these is a
layer of pigment, which is penetrated by fusiform filamentary
prolongations of each cylinder. Whence is effected the con-

270 MULLER ON THE RETINA.

nexion with the outer layers of the retina, of which the last
or outermost is the horizontal expansion of the fibres of the
optic nerve. Thus the arrangement of the elements is one,
pretty nearly the opposite of that which obtains in the Verte-
brata.

In this case, at all events, it is evident that the light must
penetrate the innermost bacillar layer, in order to reach the
other elements of the retina.

At the same time it is hardly conceivable that the light
should act directly upon the fibres of the optic nerve, which
lie far behind the pigment, since it is certain that no image
can be there formed.

The perception of the latter must rather, in the first instance,
proceed only from the radially-disposed elements, which alone
are opposed to the light.

This function must be assigned either to the continuations
of the innermost “ rod-like” cylinders, corresponding in some
degree to the “cones” of the Vertebrata, and which project
into the pigmentary layer, whilst the cylinders themselves
would serve for the isolated conduction of the impression, or,
it may be, the cylinders themselves are destined for the per-
ception, and all that lies behind them, merely for the con-
duction.

Thus the arrangement agrees very much with the notion,
which, & priori, appears to be the most plausible; that most
internally there is a mosaic layer for the reception of light, be-
hind that a pigment for the absorption of the light which has
been admitted, traversed by radial filaments, which communi-
cate the impression to the horizontal fibres of the optic nerve.

Now, since in these eyes there can hardly be any doubt
that the radial elements serve for the perception of the ob-
jective light, whilst the horizontal are simply subservient to
the conduction of the impression, a similar condition becomes
the more probable, also, in the Vertebrata.

The notion, that the radial elements serve for the reception
of light, involves a change in the bases upon which are
founded the considerations respecting the relations of the
smallest distinguishable retinal images to the elementary con-
stituents of that organ.

The difficulty presented in the supposition that very small
portions of the same fibre, taken longitudinally, were neces-
sarily to be regarded as possessing different perceptive pro-
perties, is removed, and, what must now be admitted, that a
fibril of the optic nerve merely conducts different impressions,
appears at all events less objectionable. The comparison of
the mosaic portion of the retina, with the calculated propor-

MULLER ON THE RETINA. Ft

tions of the smallest images, would at the same time afford
an indirect argument for or against the above view, on which
account I will add a few statements to those already adduced
by Professor Kélliker.

It is easily shown by experiments, as well as from the com-
parison of various statements (vid. Volkmann, ‘ Handw.’ d.
Phys. Art. ‘Sehen.,’ p. 331), that for a single impression, the
calculated image may be almost infinitely small, if only the
illumination be sufficiently powerful ; for instance, a small
hole in a black lamp-shade, or an object glittering in the sun.
The dimensions, thus obtained by calculation, are so many
times less than the transverse diameter of the elementary parts
of the retina in question, that unless a very incomplete union
of the luminous rays in the eye be assumed, it must be con-
cluded that it is only requisite that one of these elementary
parts should be acted upon with sufficient intensity, only in
a small point, in order to communicate the impression of
light.

On the other hand, the possibility of distinguishing the
smallest distance, shown by Volkmann to exist, might depend
upon this, whether several luminous pencils are incident upon
one or several elementary parts. It is necessary, however,
previously to consider the site of the most distinct vision,
because as we proceed towards the lateral portions of the
retina, both the optical and the anatomical conditions become
more complex.

Volkmann recognized the duplicity of the two filaments of
a spider’s web, at a calculated distance of the retinal images
of 0:0044’", and for a friend who had the most acute vision,
of 0:0025’””.

Valentin (Physiologie, II. 8, Abth. p. 259) distinguished
the distance of two micrometer lines, with a distance of
0:0022"" ; and in a second case, with one of 0:0014’’, on the
retina.

As regards my own eyes, the results derived from the
observation of a whole series of micrometer lines, or of the
lines in a steel engraving, under favourable conditions of
illumination, varied between 0°0025’” and 0:008””,

On account of the difference, which, moreover, occurs in
the perception of lines and points, I thought it would be
necessary to consider the latter also, but I found that the
differences are not very important. The distance from the
eye at which the lined and pointed spaces of a steel engraving
can no longer be recognized in their separate elements, but
appear uniform, was pretty nearly equal, with equal inter-
spaces between the latter.

272 MULLER ON THE RETINA.

Two lines, made with a fine needle-point, with an inter-
space of 0°2’”, could be recognized as double, at a distance of
about 3 feet, by transmitted light. If the number employed
by Volckman (1. c. p. 289 and 331), viz. 6:23'", be applied as
the distance of the focus from the axial point of the retina, the
distance between the retinal images would be 0°0022”’ ; in the
instance of several holes, 1-7’” apart, seen at a distance of
20 inches, the distance between the retinal images is 0:0037’”;
in that of a wire-sieve, 44 of the openings in which, taken
longitudinally, go to an inch, at a distance of about 3 feet, at
which they were still very distinctly separable, the distance of
the retinal image is : 0°0039’” ; and at 4 feet : 00027”.

If these calculations be based upon the proportions of the
eye, given by Listing (Handwiorterb. der Phys. IV. p. 496),
it is true that somewhat larger numbers are afforded ; for
instance, instead of 0-0039’” : 0:0042’". This difference,
however, particularly in greater distances, is of inconsiderable
moment. On the other hand, in peculiarly acute eyes and
under highly favourable conditions, somewhat smaller values
are presented.

Now, if the above numbers are compared with the diameter
of the larger elements in the bacillar layer, viz., the cones
(bulbs), which Kolliker found to measure 0-0025 — 0-0045’",
but in the “ yellow spot,” not more than 0-002 : 0 0024”, only
the one statement of Valentine is decidedly less, all the others
equal, or a little (but within moderate limits) larger than the
cones of the “ yellow spot.” The diameter of the “rods,” on
the other hand, is many times exceeded.

It would be impossible in any case to arrive at an absolute
correspondence, and particularly do the greater values of the
distances between the images admit of an easy explanation.
In general the intervals of several perceptible points must be
somewhat greater, because the arrangement of the points will
not readily be exactly conformable to the arrangement of the
parts of the retina, and consequently the image of a point
sometimes falls between, or in other words, upon two retinal
elements ; sometimes a single element will be touched by the
images of two points.

In greater measurements this must take place, for the reason
that the focus never represents an absolute point, but small
circles of diffraction, and the larger these are in the eye, so
much the less will it be in a condition, as Volkmann has
stated, to appreciate the smallest distances,

By the circumstance that the image of a point touches
several elements, the phenomena of irradiation may be ex-
plained, within certain limits. The distinct perception, also,

ZENKER ON DAPHNIDZ. 273

of two points, the distance between the image of which is not
quite equal to the diameter of one of the retinal elements,
might, according to the above view, be possible in a very
acute eye, because the image in a particular position might
nevertheless touch two different elements.

Thus, the facts hitherto ascertained, appear, in general, not
to be opposed to the notion that the perception of the smallest
distances depends upon the circumstance that different ele-
ments of the bacillar layer are touched by the image, and
this correspondence again, equally favours the view that, that
layer is the apparatus for the reception of the luminous
impressions.

Physiological Remarks on the Daphnide. By Dr. W. ZeEn-
KER. Miiller’s Archiv, 1851, p. 112, Pl. II.

AN organ, occurring in the Daphnide, about which a good
deal has been said, is the curious “ black spot’ in the head, in
front of the eye. It is seldom entirely wanting, as in Daphnia
brachiata, D. cornuta, M. E. (Eunica longirostris, Koch, Lyn-
ceus longirostris, Miiller, Bosmina longirostris, Baird), and
Polyphemus ; is much elongated in D. sima, and is so large in
the genus Lynceus, Miill., that it was considered by O. F.
Miiller as a second eye (Entomostraca, 1792, p. 67). Sub-
sequently, it has been looked upon as an auditory organ
(Schédler, tib. Acanthocercus rigidus, Wiegm. Arch., 1846,
bd. 1). It consists invariably of a minutely granular, black
substance, without a vestige of crystalline lenses or similar
organization, and is situated immediately upon the brain, or,
at all events, is only separated from it by a very short nerve.
It occurs not only in the Daphnoida, including the Lynceide,
Baird, but Liévin has also noticed it in Hedessa Sveboldit, a
new monoculous Phyllopod. (Branchiopoda der Danziger Ge-
gend. 1848, p. 11, Pl. II., fig. 10.)

In the full grown animal the function of this organ is not
readily made out with certainty, whilst, on the other hand, it
is during the embryonic development of the animalcules within
the mother that the nature of this black spot is most clearly
evident. It is known that in the embryo of the Daphnide
there are at first two eye-spots on both sides of the head,
which unite into a spherical mass not long before birth. At
a time when the eye-spots are only faintly indicated, and of a
brown colour, there is evident, seated on the brain, below and
in front, a solitary sharply defined deep black speck, in which
may at once be recognized the black speck of the full-grown

274 ZENKER ON DAPHNIDZ.

Daphnidz. It is necessarily formed long before the eyes, and
is thus the first developed organ of sense.

If now it be asked, what organ in the allied Crustaceans,
and especially in the Phyllopoda, corresponds with this, it
will be found in the tripartite azygous eye, which occurs so
extensively under various conditions throughout the Crusta-
ceans. It occurs as the only visual organ in Cypris, Cyclops,
&e. ; in conjunction with the aggregated eyes in Artemia, Ar-
gulus, &c.; but it appears regularly in all the Branchiopoda
and Siphonostomata as the earliest visual organ. It is always
placed immediately on the brain, thus also showing its corre-
spondence with the black spot of the Daphnide.

Another question is, whether this spot, the nature of which
we have developed in agreement with Siebold’s supposition
(Vergleich. Anat., 1848, p. 445), actually fulfils the function
of an eye during the period of embryonic life, or whether, in-
dependently of any such utility, it is formed merely in accord-
ance with the law of development of the Branchiopoda. As
the shell of the Daphnide is transparent, a certain impression
of light may be conveyed to the embryos; but as the embryo,
so long as it does not possess freedom of motion, has no need
to distinguish objects, so there is no necessity for any refractive
body. The other Branchiopoda must, however, before they
have other eyes, move about freely in ‘the water, and are,
therefore, provided with refractive bodies. In these the pig-
ment of the eye is for the most part red; in D. Pulez, on the
other hand, it is brownish red, and in Sida erystailina, black.

It therefore does not appear to be essential what form this
black spot may occasionally assume in the full-grown animal.
In the embryos it precisely resembles the form of the eye of
Cyclops. \n the young D. sima it is round, also for some
time after birth; at a later period it becomes elongated. Un-
fortunately, I have not observed in those Daphnide, in which,
when fully grown, the spot is wanting, whether they possess
one in the embryo state.

There is no doubt that an isolated Daphnia will of itself
produce new generations, and that these again will bring forth
others without impregnation, and so on for many times, and
probably without limit. This mode of propagation, which
occurs in some Insects, is one distinct from all others, and
cannot be identified either with gemmation or with an alter-
nation of generations. Gemmation does not take place in the
ovary [why not ?], and an alternation of generations does not
take place in cases where the same female individual can
produce young, being first unimpregnated and then impreg-

ZENKER ON DAPHNIDZ. 275

nated. Moreover, after impregnation there is absolutely no
difference in the development of the ovum, except that the
impregnated ovum comes to be enveloped with a firm, cor-
neous, saddle-shaped shell (the so-called Ephippium). In
the Phyllopoda this distinction even appears to fail, as Liévin,
who had noticed both the male and female in Hedessa Sie-
boldii, makes no mention of ephippian ova.

The males of the Daphnidz, it is true, are found all the
summer through; but very seldom, and, as it would seem, not
of every species. On the other hand, towards winter they
become much more numerous, so that the winter is the fittest
season for the study of their sexual relations. All the species
of Daphnidz succeed each other in the production of male
individuals. The males of most of the true Daphnie are met
with in October, whilst those of Lynceus abound more towards
Christmas. In consequence of impregnation a large number
of ephippia are produced, in which the ova are probably more
protected against decomposition or untimely development than
from cold. The same succession prevails with regard to the
ephippia, in the different species, as in the appearance of the
males. It would thus fairly appear that the ephippia are a
product of impregnation. Direct experiments, however, have
not as yet been instituted, to determine whether impregnation
precedes each ephippium, and each impregnation is followed
by an ephippium. At last, as the temperature lessens, scarcely
any but males are produced, and the animal disappears from
the water; at the bottom of which, however, in the submerged
ephippia, provision is made for the revival of future gene-
rations,

The males are distinguished, even externally, from the
females by the different formation of certain members, espe-
cially of the antennz, the first pair of legs, and the tail; for
the most part, also, in the size and width of the body, the
males being smaller, and wanting the uterine cavity under the
back. Internally the testis may be distinctly recognized as a
single organ, corresponding in form and position with the ovary.
Evadne Nordmanni is the only species in which, up to the
present time, the existence of the testis has been indicated
with certainty by Liévin.

The simplest form of this gland is presented in Sida erystal-
lina. Wf the creature be placed on the side, the testis lies
immediately upon the intestine, and is at once seen when the
focus of the microscope is a little raised. It is parallel with
the intestine, about half as broad, and extends from the last to
the first pair of feet, being curved at the extremity, which looks
forwards. The opening of the gland is situated in the tail, on

276 ZENKER ON DAPHNIDZ.

the abdominal or pedal aspect. This opening varies but little
in its position throughout the Daphnide. The analogy
between the testes and ovary is most evident in Sida, and they
might readily be confounded, were not their contents very
different. Whilst in the female, the ova, with germinal vesicle,
and surrounded with a vitelline substance, are evident, the
contents of the testes, which exhibit in all respects similar
forms, consist of the well-known nucleated, immotile, sper-
matozoid cells, which are peculiar to some Crustaceans. They
are formed in the curved cecal extremity of the testes, from
cells, the structure of which, on account of their minuteness,
cannot be further made out. The spermatic cell, however,
itself, is only about 0.001'” large.

In this species the male differs externally but little from the
female. It is somewhat smaller (males 1.0’, females 1.2'”),
The antennz are two-jointed, and the basal joint runs out into
a strong lateral spine, supporting a serrated seta, and pushing
the second joint to the side. The latter supports the antennal
seta, minutely described by Schédler.

As the genus Daphnia stands nearest to Sida in the sim-
plicity of the intestinal canal, so does it also in the simple
construction of the testes and ovary. The difference between
the two genera is exhibited more in the arrangement of the
muscles and the form of the joints than in the viscera. ‘Thus
the testis in D. Pulex is exactly as in Sida erystallina. The
antennz, also, are formed in an analogous way, except that they
are jointed. The beak of the male projects a little more than
that of the female. The caudal portion of the body supports,
besides the usual caudal sete, a motile papilla, in the same
situation as that in which, in the female, the teeth for the
retention of the ova are placed. This papilla, which is pecu-
liar to the male of Daphnia Pulex, is covered with scales, and
resembles in many respects the points at the margin of the
shells, within which it is frequently placed, in order to draw
the body of the animal more firmly between the shells. Neither
Jurine nor Strauss figure this papilla, nor is it mentioned by
Liévin. The male is considerably smaller than the female. I
have also had an opportunity of observing the very interesting
formation of the sexual organs in the genus Lynceus. It differs
from that which obtains in Daphnia principally in the curved
or twisted intestine ; and as in the previous case, so also in
this, does the testis present a corresponding relation. It is
curved backwards once, parallel with the intestine on both
sides. Here again, also, is shown an analogy with the ovary,
which itself runs straight between the first and fourth pair of
feet, but the excretory duct of which follows the curvature of

ZENKER ON DAPHNIDZ. 277

the intestine. At its cecal extremity the testis is again curved
backwards and inwards ; but it is not there only that its secre-
tion is formed ; this is produced, also, in certain cecal pouches,
which branch out from the testis in a backward and upward
direction. Both testes open in the tail, at the point above
indicated ; their vasa deferentia continue separate to the last.

These points are seen most simply in L. macrurus, which
differs from the female only in the form of the antenne ;
possessing, however, the same broad form and long tail as
the latter.

In L. lamellatus the testis between the curvature and the
opening is furnished on each side with a large vesicle, which
may be termed a vesica copulativa, and from which the secre-
tion may be expressed. The above, with the addition of
L. sphericus, are the only Daphnidz with the males of which
we are acquainted. The time to look for the rest is the winter.
I suppose, from the similarity with the Phyllopoda, which has
already been so frequently adverted to, that the males of that
family also will be found principally in the winter.

[In Chirocephalus diaphanus, Prev., Branchipus stagnalis,
M.E., the number of males is very considerable, and pretty
nearly equal to that of the females at all times of the year.
This fact seems to afford a curious confirmation to Dr.
Zenker’s opinion, that the chief object of male impregnation
is the production of ephippian or winter ova. Jn the case of
Chirocephalus this provision becomes repeatedly necessary
during the year, and not towards winter only ; for it is a re-
markable fact, on Blackheath, at all events, that the Chiro-
cephalus is never found in any of the several ponds on the
heath, except in those which dry up completely, at least
once, but in most years several times, or for the whole sum-
mer continuously. The ponds inhabited by the Chirocephalus,
in fact, are merely pools formed by the drainage from the
roads. Now it is manifest, under these circumstances, that,
were not provision made by the formation of winter ova, or
ova having a thick double coat for the revival of the race
after the drying up of their habitation, it would become ex-
tinct. We accordingly find that such provision is made in
the numerous males at all times present. The extraordinary
power. possessed by the ova of Chirocephalus of resistance to
the effects of desiccation is very remarkable, as is also the
readiness and rapidity with which they are developed when
again subjected to the influence of water. If the basin of a
small pool which has been dry, and even dusty, for months,
becomes filled after a few days’ rain, the water will be found
swarming with myriads of Chirocephali in about ten days or

VOL, I. U

278 SCHULTZE ON THE CHLOROPHYLL OF PLANTS.

a fortnight. Or if a piece of the dried bottom of such a pool
be placed in a pailful of water, numerous Chirocephali will be
hatched from it in the same time. The reason for this curious
arrangement with respect to the Chirocephali is obvious
enough. These delicate creatures, themselves vegetable
feeders, are the prey of innumerable enemies; among the
chief of which are the larve of Dytiscus, and of dragon flies,
&c. In ponds which never dry up, these voracious enemies
have time and opportunity to destroy the whole race of Chiro-
cephali ; but in the favourite haunts of the latter, their enemies
not being able to survive the drying up of the water, are
cleared off on each such occasion ; and the Chirocephali, being
rapidly hatched, have, as a race, time to propagate and deposit
their posterity in safety for another resurrection.— Eb. |

On the Identity of a Colouring Matter present in several
Animals with the Cutoropuytt of Prants. By M. Max
Scnutrze, of Greifswald. Comptes-rendus, Tome xxxiv.

pp. 683. May 1852.

THe author enumerates several animals of a green colour,
which are common in ditches and marshes—such as Hydra
viridis, several green Turbellaria, Vortex viridis, Mesostomum
viridatum, and Derostomum cecum; and also several green
Infusoria, such as Stentor polymorphus, Ophrydium versatile,
Bursaria vernalis, &c. The colour in these animals is afforded
by minute green globules, about 0.016 inch in diameter, which
are situated under the integument in the parenchyma of the
animals, ‘They are perfectly spherical, and exhibit within
the green substance an extremely minute, colourless, and
homogeneous nucleus ; or they may consist of several minute
green globules, grouped together in a mulberry form; in this
latter case they arise from the division of a homogeneous
vesicle.

This green colouring substance is not altered by dilute
acids or alkaline solutions ; by which it is distinguished from
the green colouring matter of several Alga, which according
to Niigeli is changed into a yellow orange or red by the same
re-agents. Concentrated sulphuric and muriatic acids dissolve
the colouring matter; the solution is of a beautiful green or
bluish green colour, unchanged by the action of heat ; it is also
dissolved by a concentrated solution of potass—by ammonia,
alcohol, and wether, the colour precisely resembling that of a
solution of chlorophyll,

BLANCHARD ON THE BLOOD IN THE ARACHNIDA. 279

Its development, also, is influenced in the same way as
that of Vegetable chlorophyll by light; but animals con-
taining it do not evolve oxygen, and the author thence con-
cludes that the evolution of that gas is not solely dependent
upon the chlorophyll in plants.

In Vortex viridis, the minute green globules, owing to their
mutual compression, assume an hexagonal form—the green
compartments thus formed are separated by an interstitial
colourless substance. The existence of a colourless membrane
around each green vesicle may thence be deduced. This fact
is further demonstrated in vesicles, the green matter of which
only partially fills the globular cavity.

With respect to the chemical composition of the membrane
and of the nucleus of the vesicles in Vortex viridis, the results
of the author’s researches are limited to the following facts,—
the solutions of potass, and of ammonia, and sulphuric acid,
after the extraction of the colouring matter, cause the mem-
brane to swell out, in which the nucleus can no longer be
recognised. The membrane becomes pale and finally dis-
appears entirely, but especially so after long boiling. Acetic
and chromic acids and alcohol do not affect the membrane and
the nucleus. By solution of iodine the vesicle is coloured
brown, the nucleus becomes more distinct, but its colour is
unaltered. It cannot consequently be assimilated to the nucleus
of the vegetable chlorophyll vesicle, which most frequently
consists of amylum.

Observations on the Circulation of the Blood in the ARACHNIDA.
By M. Emice Biancuarp. Comptes-rendus, Tome xxxiy.

pp. 402.

By the injection of the blood-vessels of a large Mygale (M.
Blondii) M. Blanchard was successful in tracing and dissecting
all the arteries distributed to the various organs, to their ulti-
mate ramifications, which he describes. The venous system
is much less perfect, consisting for the most part of canals
without walls admitting of their being isolated by dissection—
except in certain situations. He concludes in remarking that
the circulation of the blood in the Arachnida is effected by
means of an arterial system of the most complete kind, and
of a venous system very imperfect it must be confessed com-
pared with that of the Vertebrata, but which nevertheless,
owing to the great regularity of its course and its limits,
which are so well circumscribed, exhibits a degree of perfec-
tion not, hitherto, well established.

uz

( 280 )

REVIEWS.

THE SEA-SIDE Book ; BEING AN INTRODUCTION TO THE NaTuRAL HISTORY
oF THE BritisH Coasts. By W.H. Harvey, M.D., M.R.I.A., &c.
London. Van Voorst (sec. ed.), 1849, pp. 264, 12mo.

A notice of this work, published in 1849, may seem some-
what out of date in 1853; but, in the first place, even had not
the brief existence of this Journal necessarily prevented an
earlier reference to it, we do not think that the mere lapse of
time since its appearance should deter us from recommending
to our readers so pleasant and instructive a companion, espe-
cially at this season of the year, when so many of them, as
we hope, will be preparing for a sea-side ramble, and about
to enjoy, for health or relaxation, the vivifying breezes of the
ocean. Neither is a notice of the book out of place in this
Journal, seeing that Dr. Harvey has devoted a chapter, and a
very interesting one, specially to the ‘‘ Microscopic Wonders
of the Sea.”’* ;

The “sea!” that magic word to the wearied denizen of
towns, whose only glimpse of nature, perhaps for eleven
months in the year, is obtained in a dusty, suburban road, or
London square ;—with what varied tastes are its refreshing
breezes sought, and in what different senses enjoyed! but to
none, perhaps, does it offer greater attraction than to those
who delight in inquiring into the microscopic world of nature.
Nowhere in her wide domain will be found so many, and
such diverse objects of microscopic research as are afforded in
the sea, and on its rocky or sandy shores. On rock or sand,
bare, or covered with the russet garb of Nereis, the diligent
seeker will never fail to find subjects for contemplation, end-
less interest, and instructive study. The pages of the Trans-
actions of the Microscopical Society alone, bear witness to
the numerous objects of research afforded in the tiny denizens
of the sea; and to the attentive microscopic study of these

* The high estimation in which Dr. Harvey’s book is justly held, may
be deduced from the fact that an influential Society has thought it ex-
pedient (whether properly or otherwise is another question) to publish a
very close imitation of it, under the name of the ‘ Book for the Sea-side ;’
with reference to which all we would observe is, that the external imitation
has been much more successfully executed than the internal. Our readers
will observe that the ‘ Book for the Sea-side’ is not the ‘Sea-side Book’
that we recommend to them.

HARVEY’S SEA-SIDE BOOK. 281

creatures are we greatly indebted for many important ad-
vances which have of late been made in physiological and
anatomical knowledge. To these creatures, as well as to
many others, Professor Harvey’s little work will afford a
pleasant introduction. All, of course, do not take interest in
the same subject; and here we naturally address ourselves
only to those whose predilections may incline them to inves-
tigate the habits and structure of the minutest works of
Nature, with which the shore will so abundantly supply them,
or with which they may supply themselves, By the aid of very
simple appliances.

In his fourth chapter, Professor Harvey, in discoursing of
the “* Zoology of the rocky sea-shore,” says—‘“ In the vegeta-
tion of the sea nature has provided both shelter and food for
an infinitude of animals. ... . Troop after troop of animals,
one more highly organized than another, either derives its
nourishment from the sea-weed itself, or uses the submarine
forest as a hunting-ground, where it fulfils the appointed
course of its busy life. Adhering to the roots of sea-weeds
we find the scarcely organized, but obviously animated,
sponge... .. To the stems and leaves adhere multitudes of
incrusting animals, some of which, till we examine them some-
what closely, and watch their animal motions and propensities
with some care, seem to consist merely of masses of jelly ; while
others display in their outward forms the branching appear-
ance of mosses ; every branch clothed with scales, and crowned,
when the animal is in vigour, with starry flowers.”

The latter class, or the so-termed zoophytes, will almost
everywhere afford the most varied and interesting objects for
microscopic observation, For an account of the different
species to be met with on the British coasts, the best works
of reference are Dr. Johnston’s ‘ British Zooplhytes, or for
those who may be content with a less extensive work—a little
book, of which we have given a notice in a previous num-
ber—Dr. Landsborough’s ‘ Popular British Zoophytes.’* Some
of these creatures will be found adhering to the side of almost
every rock-pool left by the retiring tide, or adhering to the
roots or leaves of numerous fuct?. Many appear to prefer old
shells or loose pebbles, and some of the most beautiful and
interesting forms will be found in such situations; in ap-

* We should here, also, have referred to Mr. Gosse’s recent work, ‘A
Naturalist’s Rambles on the Devonshire Coast,” but it has not come into
our hands until these sheets are passing through the press. We reserve a
notice of this highly interesting boot —particularly to the Microscopist—
for our next number, in the meanwhi strongly recommending it to our
readers.

282 HARVEY'S SEA-SIDE BOOK.

pearance to the naked eye—nothing but a scurfy scale.
These rocky or tidal pools should be often and diligently
searched ; for the number and variety of minute animal and
vegetable forms to be found within the narrow precincts of
one of these Lilliputian lakes is astonishing. ‘‘ Nothing,”
as Dr. Harvey says, “‘ can exceed the beauty of a clear rock-
pool seen under strong sunlight, and through a calm surface,
tenanted by its various animated tribes, all fulfilling the duties
allotted to their several kinds.” In them will be found, ad-
hering to the weeds, or to the rocks themselves, an infinitude of
species of Zoophytes, sponges, minute crustaceans, and the
elegant forms of different Lucernarie, together with many of
the smaller and most delicate fuci. Leaving the rocks for the
more sandy parts of the shore, we shall find ‘along the
margin of the tide, as well as at different levels of the beach,
and in the crevices of the rock-pools, small patches of drifted
sand and shells, the examination of which will often afford
the patient explorer a rich treat.’””—‘ Careful examination with
a lens will generally detect a multitude of minute shells, some
of very strange shapes, and others structures of great elegance.”
These are the various species of Foraminifera, with many of
which, in the dead state, most of our readers are probably well
acquainted ; few, however, have studied them in a living con-
dition, and this study we would recommend as one of great
interest and importance. The same drift-sand will often be
found to contain a ‘‘ wonderful variety of minute spiral uni-
valve shells,” ‘‘ though these are scarcely of so small a size as
to come within the list of genuine microscopic objects.”
“* Others may be obtained by the gatherers of sea-weeds with
little trouble, if they will only preserve the sediment that
collects in the water in which the sea-weeds are washed.”
‘When the sea-weeds are plunged into fresh water, these
minute molluses (Rissoe) are quickly killed, and fall to the
bottom, and may then be secured by simply straining the
water through a piece of canvas. Many other minute and
curious animals, and sometimes Diatomacee, may be collected
in a similar way.”

Having thus surveyed the rocks, and sands, and weeds of
the shore above low-water mark—if we launch upon the deep
itself, a similar abundance of minute and interesting forms is
still presented to us. A small muslin bag, the ‘mouths of
which is kept open by a wire-ring about 4 inches in diameter
—towed slowly behind a boat, on a calm and bright day in
any sheltered bay or inlet—will be found to gather multitudes
of creatures of the most beautiful forms, and occasionally most
brilliant colours — creatures whose crystalline substance affords

HARVEY’S SEA SIDE BOOK. 283

to our wondering gaze a ready insight into many things con-
nected with the structure of the lower animals, which will in
vain be sought elsewhere. In this way are collected the
numerous species of minute naked-eyed Meduse, so well
described and graphically figured in Professor Ed. Forbes’
work,* cited below, and which should accompany every
microscopic observer to the sea-side. Nothing can be con-
ceived more elegant and graceful than the motions of these
minute crystalline bodies in a glass of water. Some as bril-
liant as diamonds with tiny emeralds set round the edge;
others like the beautiful Turris neglecta, resembling rubies
encased in crystal—rising and sinking through the clear water
with the most easy and elegant movements. In the dark, also,
most of these little gems will be seen to be furnished with a
row of luminous spots around the edge of the disc, at the
base of the tentacles, and it is to them, in great measure, that
the luminosity of the sea is owing. On almost every part of
the coast, besides these forms and the allied Beroes, the tow-
ing-net will frequently gather innumerable specimens of a
creature resembling a slender spicula of glass, about an inch
in length, but which is so slender and so transparent as to be
almost invisible except in a particular direction of the light—
this is the Sagitta bipunctata, and its simple structure affords
an excellent subject of microscopic research. When fishing
for objects of this kind, it is best to have in the boat a large
white basin half filled with sea-water, and into this the towing-
net is to be inverted and gently shaken every now and then.
In this way the delicate creatures it contains will come out of
it without injury, and though themselves, perhaps, at first
wholly invisible, their shadows will be seen with great dis-
tinctness against the white bottom of the basin, and thus many
forms which might otherwise altogether escape observation,
be rendered evident.

The microscopic wonders of the sea, however, are still far
from exhausted ; it presents as many, if not more, curiosities
at the bottom, where its depths are never opened to view, than
at the surface. The best and most convenient mode of obtain-
ing these, is by the use of an instrument, with which all,
perhaps, are acquainted in one shape or another, viz., the
dredge ; but the naturalist’s dredge is not a stone dredge, ora
raud dredge, or an oyster dredge, or in fact anything but what
it is, the “naturalist’s dredge.’ An instrument of this kind
is ficured and described by Dr. Harvey; but its construction
is very simple, and may be effected, if need be, by almost any

* Prof. E. Forbes. British Naked-eyed Medusew. A Monograph. Pub-
lished by the Ray Society. 1847.

284 HANNOVER ON THE

country blacksmith. The essential qualities of a dredge of
this kind are, a small and convenient size, with sufficient
weight to ensure its sinking to, and keeping at, the bottom,
even when at a considerable depth and drawn with some
velocity through the water. The dredge we have been in the
habit of using for several years past is made of cast-iron,
which reduces the cost considerably—and it is in practice
found to be sufficiently strong. It is about 18 inches in
length, and the opening is about 4 inches wide—the two sides
diverging outwards, at a slight angle, and coming to a sharp
edge. It packs with the net-bag in a box about 2 feet long
and 6 inches wide and high, and consequently makes a con-
venient-sized package. For the little information requisite
in the use of the dredge, we would refer to Dr. Harvey’s
chapter on the subject, and will merely remark, that ‘ dredg-
ing” will be found as pleasing and interesting a pursuit at
the sea-side as any that can be there followed, and one that
more than any other will, at times, be rewarded by an abundant
harvest of objects of natural history.

Recommending our readers thus to invade the domains of
Neptune, armed with microscope, towing-net, and dredge, we
can assure them that no one will have cause, even in the most
secluded nook of the coast, to complain of a single dull hour,
and if he does not return to his labours reinvigorated both in
body and mind, and with a fund of subjects for instructive
contemplation for the year to come, all we can say is—that
it will be entirely his own fault.

ON THE ConsTRUCTION aND Use or THE Microscopr. By ADOLPHE
Hannover, MD., &c. Edited by Jonn Goonsir, F.R.S.E., &c. Edin-
burgh. Sutherland and Knox. 1858, pp. 100.

Dr. Hannover’s book is short, which is a great reeommenda-
tion, and it contains many judicious and useful observations,
and is evidently the production of an experienced micro-
scopist ; but we really can scarcely find in it much that should
entitle it to appear in an English dress, as it is quite evident
that the author is totally unacquainted with the present state
of the microscope in this country, however familiar he may
be with those of foreign construction. He does not mention,
and appears to be unacquainted with any English microscope
maker except Mr. Pritchard. Were he aware of what they
have done, and still are daily doing, towards the perfection of
the microscope as an instrument of scientific research, Dr, Han-
nover would surely have referred to the labours of Ross,

CONSTRUCTION OF THE MICROSCOPE. 285

Powell, and of Smith and Beck ; men who, with the aid of
Mr. Lister, have done more in the improvement of the achro-
matic microscope than all the continental opticians together,
and whose instruments, both for optical perfection and
mechanical contrivances are, as we believe, unrivalled by
those of any country in the world. But we are indeed sur-
prised that his learned English editor should have been
content thus to ignore the merits of his countrymen, and to
omit all notice of some of the most important improvements
in the microscope and its appliances, which have now been
long in daily use. Many other proofs of Dr. Hannover’s
want of information on the points to which we have referred
might be adduced, but we wouid merely, in justification of
what we have said, remark, that he appears to be quite
ignorant that object-glasses may be made to adjust to varying
thicknesses of the glass employed to cover an object (pp. 25,
59), although the mode in which this adjustment might be
made was described by Mr. Ross as long ago as 1837, and has
been universally adopted by English opticians since that
time. He makes no mention either of any of the more
recent, ingenious, and most valuable modes of illumination,
to which, for some time past, so much and such successful
attention has been paid. We refer more particularly to such
contrivances as Gillett’s condenser, and the parabolic reflec-
tors of Wenham and Shadbolt.

The book, however, as we have said, contains many
judicious observations and directions useful to the young
microscopist ; and the preliminary observations present, in a
small compass and in plain language, as good an exposition
of the principal optical considerations which are concerned in
the structure and use of the microscope, as can, we think, be
anywhere found within the same limits.

The first chapter is devoted to an account of the simple
microscope ; and chapter ii. is on the construction of the com-
pound microscope and its accessories; but neither in these
nor in the subsequent chapters, containing directions for the
use of the instrument, do we observe anything from its novelty
worthy of particular notice—at all events by those who have
it in their power to refer to Mr. Quekett’s much fuller and
more practical work.

The author’s observations on Micrometry are good, and
wiil be found worth consultation, as is also what he says
about the modes of estimating the magnifying power of an
instrument, and for calculating the amount of spherical
aberration of any combination (p. 75). With reference to this
he takes occasion to remark, that the same mode of observa-

286 ROSSMASSLER’S MICROSCOPIC GLANCE INTO THE >

tion enabled him to judge whether his eyes had remained
unchanged or not during four or five years, notwithstanding
the almost daily use of the microscope. He found that dur-
ing that period the sight of his right eye had become only
41-10-000ths —1-244th shorter; and observes, ‘“‘this was
satisfactory to myself, and it may also set those persons at
rest who are fearful lest the use of the microscope should
injure the eye ”’—which would be true were the alteration of
the focal range of the eye the only consequence that can arise
from the prolonged use of the microscope, especially by
artificial light, against which we are fully in accord with
Dr. Hannover, in warning all who have regard to the pre-
servation of unimpaired visual powers.

We subjoin the following table of comparative micro-
metrical measures, given by Dr. Hannover, as it may be useful
for reference in our pages :—

Millemetre. Paris Lines. | Vienna Lines. | Rhenish Lines.| English Inch.

1 0° 443296 | 0°4555550 0°458813 0°0393708

2° 255829 1 1°027643 1°0350038 0°0888138

2°195149 0°973101 1 1°0071625 0*0864248

2°179538 | 0°966181 0°992888 “1 0°0858101
25°39954 | 11°25952 | 11°57076 11°65364 1

MIKROSKOPISCHE BLICKE IN DEN INNEREN BAav UND DAS LEBEN DER
GrewicusE, &c. (Microscopical Glance into the Intimate Structure and
Life of Plants. In the form of Popular Lectures.) By E. A. Ross-
MASSLER. With 15 mostly coloured lithographic plates. 118 pp. 8vo.

Tue whole is contained in four discourses. In the first the
author compares the different modes in which natural history,
or the idea contained in it, is comprehended by different
classes of minds. To the one it is simply a chamber of
mystery—to another a study—to a third a means of climbing
to ease and renown—to a fourth a picture-book. To all, he
says, it ought to be a “beautiful maternal home, to be a
stranger in which should be regarded, in any one, as a loss
and shame.” He touches upon the question whether natural
history is a real or merely a humanistic science, and decides
in favour of the latter, seeing that the homo is still a part of
the kingdom of nature—a convenient, but surely a dangerous
argument! He lauds the value of the microscope in the
natural sciences ; and then proceeds, in more immediate appli-

INTIMATE STRUCTURE AND LIFE OF PLANTS. 287

cation to his subject, to show, that plants consist of cells,
explaining what is meant by the latter. In the second dis-
course the theme is continued ; the peculiar forms of cells are
described, and then the cell-contents: colouring matter, crys-
tals, nucleus, starch, and the spiral filaments, The ensuing
chapter discourses about the vessels and their modifications,
and then adverts to the tissues formed immediately from the
elementary organs, such as the cuticle with its stomata, hairs,
setae, and scales; to the structure of the leaf and ligneous
stem in the mono- and dicotyledonous plants. The fourth
chapter embraces the distinction between animals and plants,
with respect to individuality and their various vital actions ;
the nutrition of plants and their importance with respect to
the habitability of the earth ; and lastly, the alternating rela-
tion between animals and plants. The last discourse treats of
the root, the changes of matter effected in the interior of
plants, the ascent and descent of the nutritive sap, and finally,
of the parts belonging to fructification, and of fructification itself,

The illustrations, which are well designed and well executed,
are copies from the larger figures employed by the author in
his lectures. Of course in a work like this the utmost scien-
tific precision is not to be expected nor many original views
or facts ; and the mode of treatment requisite in a course of
popular lectures necessarily implies that many things must be
superficially treated; we have no doubt, however, that the
little work will obtain numerous readers, who will not fail to
find in it an interesting and eloquent exposition of the subjects
of which it professes to treat.

PRINCIPLES OF THE ANATOMY AND PuysioLoGy oF THE VEGETABLE
Crtt. By Hueo von Mont, Translated by Arruur Henrrey, I.R.5.
London. Van Voorst.

Tuer use of the microscope alone has rendered the production
of sucha work as this possible. It is only a few years ago, if
the existence of cells in plants was not altogether ignored, that
their presence was regarded as a matter of little or no conse-
quence, and vegetable physiologists speculated on the fune-
tions of plants, without knowing anything of the agencies
by which they were produced. Microscopic research has,
however, shown us that it is in the interior of these minute
constituents of vegetable tissue that all the functions of plants
are carried on. Hence we may truly say that the principles
of the anatomy and physiology of the vegetable cell are the
principles of vegetable anatomy and physiology.

288 MOHL’S PRINCIPLES OF THE ANATOMY AND

To few men are we more indebted for the light that bas
been thrown on the functions of plants by the aid of the
microscope than to Hugo von Mohl. From the time of one
of his earliest publication on the pores of cellular tissue to
the present, his contributions to the microscopic anatomy
of plants have been very constant. ‘To no one, therefore,
could we listen more attentively on the subject of this work
than to Hugo von Mohl. Nor is the subject of vegetable
structure and physiology in so advanced a position as to leave
little further to be done for its advancement. At present,
the great proportion of our botanical literature gives indica-
tions that it is not yet emancipated from the influence of
theories which were constructed at a time when only the
most imperfect knowledge of the true structure of plants
existed. Much of our vegetable physiology has to be re-
constructed, and it is only by studying the phenomena of
plant-life, as it presents itself in the simplest conditions, that
we can expect to understand its more complicated forms.
It is true that some of the younger botanists have thrown
off altogether any allegiance to the older school of physio-
logists, and have determined to accept no theory that
does not originate in microscopic research; but in them
we have only the reaction that was a natural consequence
of the new aspect which microscopic investigations gave to
the functions of vegetable life. Amidst the different teachings
of opposed schools, Hugo von Mohl will be found a safe
guide for those who are anxious to understand the general
laws which govern the life of the plant.

It must not, however, be supposed, that this is a work on
morphological or systematic botany. ‘The only point of view
from which it contemplates the plant, is its origin, and that
of all its parts, and the functions it performs, in the cell. To
the amateur microscopist, to the animal physiologist, to the
practitioner of medicine, to the student ambitious of grasping
the general laws which govern the relations of the mineral,
vegetable, and animal kingdoms, this work will supply those
facts and principles in which they are each most interested.
The matter is arranged under two principal heads, the
anatomical conditions of the cell, and the physiological con-
ditions of the cell—the cell at rest, and the cell in action.
Under the first head, we have the form, the size, the walls,
the contents, the relations, and the origin of the cell dis-
cussed, In the latter division, the cell is regarded—l. As
an organ of nutrition; 2. As an organ of propagation; 3. As
an organ of motion. In going over this wide field, Professor
von Mohl discusses many controverted points, to some of

PHYSIOLOGY OF THE VEGETABLE CELL. 289

which we should have been glad to have drawn attention had
our space permitted. As he has distinguished himself by his
researches upon the origin of the vegetable cell, we give an
extract from this section of his work, relating to the differ-

ences of opinion which have existed between himself and
Schleiden:—

To Schleiden belongs the merit of discovering free cell-formation and
the dependence in which the origin of a cell stands to the formation of a
nucleus ; but he was led by this discovery to the misconception that this
was the only mode of formation of the cell occurring in nature. In ac-
cordance with this hypothesis, the cells which were formed in other cells
would always be much smaller than the parent-cells, and would gradually
expand until they filled up the cavity of the parent-cells, and their walls
came into contact. But as the whole process could not take place in cells
which contain granular structures, such as chlorophyll or starch granules,
or the like, without the displacement of these structures, and yet in a cell
of that kind in which division occurs, all these structures are still present
after the division, Schleiden invented an hypothesis to explain the circum-
stance, namely, that these structures in the cavity of the parent-cell were
dissolved outside the secondary cell, and formed anew inside it. But as
nothing of this process can be observed in nature, it alone suffices to refute
the doctrine of the universality of free cell-formation. Even when quite
recently, in consequence of Nageli’s observations, Schleiden (Grundz.,
3rd ed. i. 213) can no longer deny that a division of cells does occur, still
he is far from acknowledging the universal diffusion of this process, since
he only refers to the older notion, retracted by Nageli himself, that this
mode of formation occurs in the Phanerogamia or in the special parent-
cells of the pollen-grains, and altogether ignores the fact that Nageli and
others have shown this to be the mode of formation of all cells except
those originating in the embryo-sac ; consequently, Schleiden still ascribes
to free cell-formation an influence on the development of the plant which
by no means belongs to it. When he states that the cells are developed
in this way in the embryonal vesicle, this is decidedly false, for all recent
observations agree in showing that the embryo originates from the germinal
vesicle by cell-division ; not less incorrect is it, that free cell-formation
may be traced in jointed hairs, and just as little does it accord with the
mode of formation of other plants that, as is stated (@rundz., i. 211),
cells are formed in cells, and the parent-cells absorbed, in the points of
the roots and shoots of the stem of Cypripedium. The entire representation
proves that Schleiden has never once observed the division of a cell.

The first account given by Schleiden (Beitr. zur Phytogenesis, Muller’s
Archiv., 1848) of the process of cell-formation, was faulty in many re-
spects. He altogether overlooked the important circumstance that the
nitrogenous substances were the originators of the formation of the nuclei
and the cell, for he believed the granules of protoplasm, which he deno-
minated mucilage (schleim), to be identical with the granules of gum, and
thought that the protoplasm might be replaced by starch, and go through
similar metamorphoses ; for he expressly mentions that starch, or the
granular mucilage replacing it, is present in the pollen-tubes, but those
substances are soon dissolved, or change into sugar or gum. In the forma-
tion of a nucleus those little mucilaginous granules were produced in the
protoplasm, then a few larger granules, and soon afterwards the nuclei
showed themselves. When a cell was formed, it had at first the form of
a segment of a sphere, the plane side formed by the cytoblast, the convex
side by the cell-membrane. Originally the cell-membrane was soluble

290 MOHL’S PRINCIPLES OF THE ANATOMY AND

in water, but it soon expanded more and more, and acquired greater con-
sistence ; and its walls, with the exception of the cytoblast, which always
formed part of the wall, were composed of gelatine. The cell now soon
became so large, that the cytoblast appeared only as a little body enclosed
in the lateral wall. The cytoblast might go through the whole vital
process with a cell, if it were not dissolved and absorbed in cells destined
to higher development, either in its place, or after it had been cast off like
an useless member, in the cavity of the cell.—The whole of this account
of the relation of the nucleus to the cell-membrane is incorrect. ‘The
nucleus is not connected with the cell-membrane under any circumstances,
for it is enclosed, with all the rest of the contents of the cell, in the
primordial utricle. Its position in the newly originating cell is, as appears
to me, always central, and its form mostly globular; it does certainly
often lie upon the wall of the cell subsequently, and becomes flattened.
The distinction which Nageli tries to carry out between central and parietal
nuclei is not founded in nature.

Another subject of no less interest to the vegetable physio-
logist, and to which Schleiden has given a peculiar view, is
the origin of the embryo in Phanerogamic plants. The
following is Mohl’s account :—

When the pollen-tube has reached the upper part of the embryo-sac,
its growth is either immediately arrested, or it becomes elongated a very
little more, so that its obtuse, somewhat inflated end usually penetrates
laterally between the embryo-sac and the surrounding cellular layer (pl. 1,
fig. 14, 15), or, in rare cases (Narcissus poeticus, according to Hofmeister ;
Digitalis purpurea, and Campanula Medium, according to Tulasne),
introverts the membrane of the embryo-sac for a short space. In ex-
tremely rare cases (in Canna, according to Hofmeister), the pollen-tube
breaks through the membrane of the embryo-sac, and thus comes imme-
diately in contact with the germinal vesicles. In the great majority of
cases, however, as already observed, the pollen-tube is separated from the
germinal vesicles by the membrane of the embryo-sac, and frequently
even, the point at which the end of the pollen-tube is in contact with the
embryo-sac, does not correspond exactly to the point at which a germinal
vesicle lies in the inside of the embryo-sac (pl. 1, fig. 15). Therefore
the only way in which a material effect can be produced by the pollen-
tube upon the germinal vesicle, is by the fluid part of the fovilla tran-
suding through the membranes of the pollen-tube, the embryo-sac, and
the germinal vesicle. It cannot be demonstrated that such a transudation
does take place, but it is in the highest degree probable, since it is incom-
prehensible how the impregnation of the germinal vesicle could take place
without it.

The pollen-tube begins to decay more or less rapidly after it has
reached the embryo-sac. Its growth is arrested, as before noticed, and
the fovilla contained in it undergoes a visible change in its characters,
acquiring a granular, half-coagulated aspect; the pollen-tube itself is by
this time evidently dead, and disappears sooner or later (sometimes, how-
ever, not until the seed is ripe), apparently through absorption,

On this subject Professor Mohl appends the following
criticism :—

Schleiden’s theory of the origin of the embryo (Hinige Blicke auf die
Entwickelungsgeschichte des veget. Organismus, Wiegmann’s <Archiv.,
1837, 1, 289—Ueber die Bildung des Hichens und Entstehung des m-

PHYSIOLOGY OF THE VEGETABLE CELL. . 291

bryo, Act. acad, nat. Cur., v. xix., p. 1) is completely opposed to the
foregoing description of this process, since, according to him, the embryo
is not formed in the cavity of the embryo-sac, but in the lower end of
the pollen-tube, which introverts the wall of the embryo-sac, and pene-
trates more or less deeply into the depression thus formed. If this theory
were true, the germinal vesicle would not be an independent product of
the ovule, but of the clavate, expanded extremity of the pollen-tube, and
the suspensor would be the remainder of the latter, running into the
introverted portion of the embryo-sac. In the whole province of Vege-
table Physiology, seldom has a theory excited so much curiosity as this
theory of impregnation. No conviction was more firmly established than
that the pollen was the impregnating organ; hence the wonder that it
should be exactly the reverse. The confusion was great, for the theory
emanated from a man who showed by his numerous and excellent re-
searches on the ovule, published at the same time, that he possessed an
acquaintance with the subject, such as few others had, and who in every
word expressed the conviction that the matter did occur as he asserted,
and that a mistake was out of the question. And others were not want-
ing to make known confirmatory observations (Wydler, Biblioth. Univers.,
1838, Oct.; Géléznoff, Bot. Zeitung, 1843, 841), or to support the new
doctrine on theoretical grounds, and teach it as a settled truth (Endlicher
and Unger, Grundz. der Botanik). It is true that the old notion had its
defenders, but these maintained the fight a long time with little success.
Some who did not know how to use the microscope, thought, nevertheless,
that an opinion might be arrived at here, in which the thing depended
wholly and solely upon a fact to be determined by the microscope, from
other grounds, but such was utterly without value by itself; others,
Meyen in particular (Physiologie, iii.), certainly had recourse to the micro-
scope, but were content with superficial observations, and thus were not
very fortunate in their intended refutation of the new theory, for obser-
vations, in some of which not even the penetration of the pollen-tube
into the ovule, or the embryo-sac were seen, were not calculated to drive
an opponent like Schleiden out of the field, and the latter could justly
interpret some among such discordant observations as Meyen’s in his own
favour. It was Amici again who now for the second time came forward
with an observation marking an epoch in the theory of impregnation, and,
by his researches on the impregnation of the Orchidex (Sulla fecundazione
delle Orchidee,—Giorn. Bot. Ttalian, Anno 2), made an end of the new
theory at one blow. Amici’s treatise was soon followed by a confirmation
of what he had seen by myself (Bot. Zeitung, 1847, 465), and others; and
these were quickly succeeded by the extensive researches of Hofmeister
(Die Entstehung d. Embryo d. Phanerogamen) and of Tulasne (Ann. d.
Se. nat. 3 Ser. xii.), which contained a full confirmation of the results
obtained in the Orchides, and demonstrated that the impregnative process
is the same in its essential circumstances throughout a long series of Pha-
nerogamia, so that this subject may be considered as quite settled in its
principal features.

There are some who will probably not agree that this sub-
ject may be regarded as “ quite settled,” but we have not space
to enter upon the discussion. We will conclude by cordially
recommending this volume to all who are interested in the
study of plants, but more especially to those who are anxious
to gain a view of the grand distinguishing features of vegetable
life, without entering upon the technical study of their strue-

ture, forms, and relations.

( 292 )

NOTES AND CORRESPONDENCE.

Mode of Betermining the Optical Power of a Microscope.—
I conclude by noticing another method of testing the optical
power of the instrument, which, although rather troublesome,
appears to me among the best, permitting us, as it does, to
ascertain with a great degree of accuracy and certainty, the
utmost limits of penetrating and separating power possessed
by a microscope, and hence easily to express numerically its
optical qualities in the most varied circumstances.

This method consists simply in subjecting to observation
under the microscope the dioptric images of certain minute
objects instead of the objects themselves. These images can
be diminished at pleasure by withdrawing to a distance from
the lens the object which forms them; and hence we have it
in our power to measure the extreme limits at which the
object continues to be visible.

For the formation of the dioptric images achromatic object-
glasses might be used; but even where: those of the shortest
focal length are employed, the object whose image it is
required to form must be placed at a great distance. This
would cause various difficulties, and only be practicable with
a microscope placed horizontally—unless, indeed, the object
selected were very minute, in which case the accurate deter-
mination of its diameter (from which that of its image must
be afterwards deduced) would be rendered difficult.

Small air-bells in a fluid are for this purpose far better.
I employ by preference a watery solution of powdered gum
arabic, which always contains numbers of such air-bells ori-
ginating in the air entangled among the particles of the
powder. The water employed should have stood for a con-
siderable time freely exposed to the air, or been shaken up
with the air for some time; for when we use water which is
not saturated with air, the bubbles in the fluid gradually
become smaller, and images formed in them decreasing in
magnitude, cause errors in the subsequent measurements, as
we shall actually find to be the case.

A drop of the fluid must then be placed on a clean glass
object-slide, and covered with a good clear mica plate, a ring-
shaped piece of paper being interposed, in order to prevent
the flattening of the air-bells by pressure. The object-slide
is then placed under the object-glass upon the stage of the

MEMORANDA. 293

microscope, and an air-bell of suitable size for the formation
of the images is sought for, All do not give images of the
same degree of sharpness ; a peculiarity dependent on the fact
that some air-bells are in contact with the covering-plate, and
consequently have their spherical form disturbed to some
extent, or on the presence of small molecules in the fluid
above or beneath the air-bell, or even in its interior, causing
some haziness of the image, just as defective polish of a glass
lens would do. It will, however, be always easy to find some*
which will form images of the utmost distinctness and purity.
This may be ascertained in the first instance by holding
between the mirror and stage some easily recognized object,
e.g. a piece of paper or the like. The image is always formed
on the under surface of the air-bell, which must consequently
be brought nearer to the object-glass than when it is desired
to bring its margins into focus.

The object whose image is to be the subject of examination
should be placed upon an apparatus, which can be moved
upwards and downwards in the space between the mirror and
stage. In some microscopes this can hardly be done, either
from the space being too limited, or in consequence of the
drum-like form of the foot of the microscope which quite
envelops the space. If such microscopes, in place of a mirror,
be provided with a reflecting prism, the object may be placed
opposite the side external to the microscope. The instru-
ments best adapted for the manipulation which we are describ-
ing are, however, those whose illuminating apparatus consists
of a mirror and converging lens, which can be shifted up or
down. The lens being removed from the ring which supports
it, the object is substituted in its place. The relative magni-
tudes of object and air-bell must be such that the image shall
be exceedingly minute when the object is tolerably near to
the stage. On afterwards increasing the distance between
the object and air-bell, it is not difficult to find the limit at
which the image (under a given magnifying power) is barely
visible.

Of course it is impossible to measure directly the dimen-
sions of this most minute visible image, for our best micro-
metric methods will here be found of no avail. Yet their size

* The following example will demonstrate this. I brought a printed
page of a book to such a distance from an air-bell that the length of the
image of the whole page was 1-7th millimetre = about 1-180th of an inch,
and that of the image of each letter about 1-480th millim. = 1-12,000th
of an inch. In spite of their minuteness, these images, formed by reflected
light, possessed such clearness and sharpness, that under a magnifying
power of 154 diameters the whole page was without difficulty legible.

VOL. I: "8

294 MEMORANDA.

may be estimated with extreme accuracy in the following
manner. At the same distance from the air-bell and in place
of the object used, substitute another body, such as a piece
of card, of 4 to 5 centimetres = 12ths to 2 inches diameter,
which has been exactly measured. Let this be now again
measured (by some of the micrometric methods elsewhere
alluded to*), just as if it were a real object. By dividing the
real diameter by the apparent diameter, the amount of dimi-
nution is found; and this is the same for all objects at a like
distance from the air-bell. We have, consequently, nothing to
do, in order to find the amount of diminution of the image of
the more minute object, but to divide its true diameter by the
figure expressing the diminishing power.

For example, let the true diameter of the greater object be
5 centimetres = to 1°969 English inches, and the diameter of
its image = 32:2 micromillemetres,f = ‘00127 English inches,
then the figure expressing the amount of diminution will be
sors7 = 1553 very nearly. If now the smaller object have a
diameter of 175 micromillimetres = ‘00689 English inches,
then must its image at the limit of vision be in diameter =
90,689 = 0000044, or about 5554;;th of an English inch.
When exact micrometric methods are employed, it is easy in
this way to estimate the diameter of an image even to millionth
parts of a millimetre, 7. e. to 25,400,000th parts of an inch.

As for the object suitable for these investigations, it is plain
that we have an extensive choice. To find the limit of vision
for bodies of a round or long thread-like form, grains of pearl
sago, or vegetable bodies, such as mustard-seed or the pollen-
granules of many plants, hairs of animals, metallic wires, &c.,
may be employed. Small round openings and chinks may
serve for the determination of the visibility of positive images
of light. In the last case care must of course be taken, by
means of suitable screens, to shut off all light except what
passes through the aperture. To determine the defining power,
metallic wire-gauze is a suitable object, or two holes placed
near each other in a black metallic plate. The images of such
objects resemble exactly a double star viewed through a
telescope (kijker). The bodies may likewise be placed in
different circumstances in order to ascertain the influence of
these upon the limits of vision, Thus we may use as an object
a very thin glass capillary-tube placed in water, and compare
it with tender organic-tubes and vessels, whiclt may also be

* See translation from //et Mikroskoop in Monthly Journal of Medical

Science, June 1852, p. 453, et seq.
+0 he micromillimetre is equal 1-1000th millimetres = *0000394 Eng-

lish inches. See Monthly Journal, June 1852, p. 456.

MEMORANDA. 295

seen in water, but whose limit of visibility is of course far
more circumscribed than that of absolutely opaque objects.

In fact this method admits of innumerable variations, and is
consequently of most extensive application. Besides, when
proper precautions are taken, it gives results perfectly sure
and comparable. Especial care is however requisite in the mode
of illumination. For it is certain, that when the field Las a
clear white ground, the contrast causes minute opaque bodies
(z. e. objects which are dark by transmitted light) to continue
visible, which against a grayish or light-blue back-ground
could not be seen. Hence it is by no means indifferent to
receive on the mirror light from a white cloud, from a dull
overcast, or clear blue sky. Artificial light cannot be used in
these experiments, for the image of the flame becomes dimi-
nished like the object, and hence a clear field of view is not to
be obtained. The observations must consequently be made
by daylight; and whenever comparable results are sought for,
the mirror should always be directed to the clear, blue, cloud-
less sky—this being a distinct atmospheric condition to which
others in similar circumstances may refer in conducting the
same experiment. The mode of ascertaining the limit of
vision, with a given amount of illumination, may be gathered
from different examples in the body of this work. It will
likewise be found that for all such observations, even when
the highest magnifying powers are employed, the /lat mirror
is perfectly sufficient, since in the image in the field of view
formed by the air-bell, all the rays proceeding from the mirror
are united and constitute an object of considerable luminous
intensity.—Proressor Hartine, Utrecht.— Monthly Journal
of Medical Science.

On a New Animaicule.—The animalcules described in the
following pages were found in great numbers in the bottom
of a small vessel or “ aquarium,” in which colonies of Pluma-
tella, Melicerta, and Limnias had been kept. Of all the
forms which can with certainty be referred to the animal king-
dom, there are few which at first sight are so little likely to
be recognized as animals as those about to be described.

If the reader will imagine a bag made of some soft exten-
sible material, so thin as to be transparent like glass, so soft
as to yield readily by extension when subjected to internal
pressure, and so small as to be microscopic; this bag, filled
with particles of sand, shells of Diatomacex, portions of Alge
or Desmidiez, and with fragments of variously coloured cot-
ton, woollen, and linen fibres, will give a picture of the
animal ; to complete which it is only necessary to add a few

x 2

296 MEMORANDA.

loose strings to the bag, to represent the variable radiant pro-
cesses which it possesses.around the mouth.

When I first saw these curious creatures they attracted but
little attention, as I supposed they were merely excrementitious
masses due to some of the aquatic animals living in the vessel
where they occurred. A more careful examination showed
that they moved spontaneously, and even with some degree of
rapidity ; and that this motion was due to radiant, branching,
and variable feelers, or “ rhizopods,” which were thrown out
near one extremity. By attaching these feelers to various
objects the animal was enabled by means of them to pull
itself along, or to change its position at will.

The most common form in which these creatures occur is
that of a pear-shaped mass having the feelers attached to the
larger end, while the other end appears almost always to be
pushed out, and rendered acute by the presence of several long
diatomaceous shells which the animals have swallowed.

Another curious set of forms appears to be produced by the
process of spontaneous fission or self-division.

The partial fission, or a budding from the sides, when com-
bined with the distortion produced by the internal pressure of
the various articles swallowed, gives rise to a variety of com-
plex and extraordinary forms. Some of these appear as if
several pear-shaped individuals were about to be produced by
a budding from the sides of the parent, but it is also certain
that some at least of these sac-like projections are only tem-
porary extensions produced by internal pressure. This was
decided beyond a doubt by a series of continued observations
upon single individuals.

The substance of which these animals are composed is much
like that composing the bodies of the various species of
Amoeba, being soft, colourless, elastic, and extensible. It is
probably without any true integument, and is coloured yellow
by tincture of iodine, It appears to resist internal pressure
with considerable force, and it is but rarely that it appears to
be completely broken through by any of the matters, however
hard, which are contained within it. I have, however, found
some individuals which had voluntarily impaled themselves
upon long fibres which were distinctly seen projecting through
the animalcules at each end, and these animals were seen
moving freely along, from one end of the fibre to the other,
without appearing to experience any inconvenience from the
perforation. I have occasionally found them attached in this
way to filaments of Conferva and Draparnaldia, which were
still alive at one extremity. The traces of internal structure
or organization are exceedingly slight. Occasionally, when a

MEMORANDA. 297

portion of the body is left vacant, some slender thread-like
lines may be seen in the interior.

In many individuals 1 have seen the protrusion from the
mouth of transparent, rounded masses, which rapidly suc-
ceeded each other until they were heaped up about the mouth
like a set of soap-bubbles, and were then as rapidly drawn in
again. ‘The more common appearance, however, is that where
the mouth is surrounded by a considerable number of slender,
colourless, radiant, branching, and retractile feelers, precisely
like the rhizopods belonging to the marine Foraminifera or
Polythalamia. When fully extended, these often exceed in
length that of the body of the animal. They change rapidly
from simple to branched, or vice versd, and are at one moment
seen in a state of tension, and then wrinkled and collapsed, or
changed into various rounded processes, which can be wholly
retracted. These feelers, tentacles, variable processes, or
rhizopods are not like the pseudopods of Amoeba, mere pro-
trusions of the surface, nor are they thrown out as in that
genus, from all parts of the animal. They, on the contrary,
resemble those of a Diffiugia, in being confined to the vicinity
of the mouth; but they are much more slender and more
repeatedly branched than in any Difflugia which I lave seen.
By means of these organs the animals pull themselves along,
when lying upon their side, and they also creep by means of
them, with the mouth downwards, moving onwards with a
slow gliding motion like that of a Diffiugia.

Besides the heterogeneous collection of matters which these
animals swallow, and which can be seen distinctly with all the
forms and colours through the transparent exterior, there is
also, in most specimens, a considerable number of small
globules scattered without order, whose nature is very doubte
ful, for as yet there is no proof whether they are ova, oil
drops, or something else.

When these creatures have swallowed bits of fibres which
have been dyed of various colours, the reds, blues, scarlets, &c.
of these filaments may be distinctly perceived through the
sides of the animal; but the spectacle becomes still more
curious when seen by polarized light, when the particles of
quartz, &c., contained within these creatures also display their
gorgeous tints.

When these creatures are dried upon glass, and then
mounted in balsam, their forms are not greatly altered, and
their contents become still more distinctly visible. It seems
scarcely probable that these animals have so little discrimina-
tion as to swallow for food all the strange mixtures of organic
and inorganic bodies which are found within them, It is pos-

298 MEMORANDA.

sible, however, that adhering to these grains of sand, fibres of
wool, &c., there may be nutritive matters deposited from the
water, which may be removed by the process of digestion, as
the soft contents of the shells of Diatomacee also appear to
be. This view is supported by the fact, that on the appli-
cation of tincture of iodine to these animals, a distinct blue
colour was often seen all over the surface of many of the
grains of sand in their stomach, The starch giving rise to
this colour, was doubtless derived from bits of boiled beans
and potatoes which had occasionally been introduced into the
aquarium as food for other animalcules. Another fact which
appears to show that the sand, &c., is not swallowed merely to
increase the absorbing surface, as Dujardin suggests may be
the case in Amoeba, is that these particles of sand are not
retained for any great length of time, but in company with
the empty shells of Diatomacee, and other remains of their
food, they are, after a while, thrown out at the mouth, which
appears to be the only aperture for their reception and dis-
charge. There appears to be no reason to doubt that the
cavity into which all these bodies are received is a true
stomach, and they therefore manifestly cannot be considered
as polygastric animals. As to the position of these creatures
in the system of Zoology, it is evident that they belong to the
Infusorial Rhizopoda of Dujardin, and connect the genus
Amoeba with Difflugia, agreeing with the first in the soft body
without shell, but differing in having true feelers or rhizopods
confined to the anterior portion of their body, and by not
throwing pseudopods from other parts. From Difflugia and
the whole family of Arcellina, these forms are distinguished
by having no lorica or shell. They are, however, closely
allied to the Arcellina, and are very nearly what some of the
species of this group would be, if deprived of their rigid ex-
ternal coverings.

In order to give to these curious beings at least a temporary
name and place, I propose to found for their reception a new
genus named and characterized as follows, viz. :—

Pamphagus, nov. gen.

Animals of the class of Rhizopoda (intermediate between
Amoeba and Arcellina) without shell or lorica, and composed of
a soft, colourless matter, easily extended by internal pressure,
but not spontaneously protruded into pseudopods. Feelers
or rhizopods, slender, numerous, radiant, branching, and con-
fined to the neighbourhood of the mouth.

Species 1. Pamphagus mutabilis—This species, which is
the only one now known, is sufficiently described above, Its

MEMORANDA. 299

habitat is probably the bottom of small pools and streams of
fresh water, as it was found in vast numbers in an aquarium
supplied from such places in the vicinity of West Point. It
will probably be found to be a common form; and as it pre-
sents the conditions of animal life in almost the lowest degree
of simplicity, and can be preserved and studied with great
ease, it will well reward the attention of microscopists. I
have thousands of these animals now living in mid-winter,
and with a little care they may probably be kept until the
return of warm weather, when other interesting facts may
possibly be added to the observations here recorded. J. W.
Bawtey.— American Journal of Science and Arts, vol. xv.

On certain peculiar Structures in the Placenta of the
Biteh.—The placenta in this animal forms a circular band
with distinctly-marked margins, on each of which, at and near
the conclusion of gestation, is an olive-green, almost black,
line, having the appearance of coagulated blood. On placing
a portion of this dark matter under the microscope, and ex-
amining it with powers varying from 200 to 600 diameters, it
was seen to contain numerous unaltered blood discs; cells
containing a bluish-green, and other cells filled with a deep
red, colouring matter. The cells containing the red-colouring
matter were almost opaque, and bore a striking resemblance
to the nodules of colouring matter so constantly seen in the
spleens of animals. The bluish-green colouring matter con-
tained in the other cells varied in tint, from brilliant blue to
bluish green, and light green in different cells. Both kinds of
colouring matter were insoluble in water, but soluble in
acetic acid and solution of caustic potass. These colouring
matters were evidently enclosed in distinct cells, of which the
membrane could be readily distinguished. The cells varied
in form ; were rounded, oval, sometimes agglutinated in masses,
and often very irregular. The cells varied in diameter, from
1-2400 to 1-343 of an inch; some of those containing the red-
colouring matter being as smal] as 1-3430 of an inch.

In addition to these colour-containing cells, an immense
multitude of minute crystals, of a light reddish tint, were
diffused over the field. They had the form of elongated,
flattened prisms, either with distinctly truncated or irregular
extremities. The colour varied from distinct red, with a play
of prismatic colours, to colourless. The more minute of the
crystals showed little colour, as might be expected, since the
red corpuscles of the blood appear scarcely coloured when
viewed with a high power under a strong light. These crys-
tals varied in length, from 1-171 to 1-1828 of an inch, and
in breadth, from 1-2400 to 1-15,000th of an inch,

300 MEMORANDA.

With regard to the origin of these colouring matters, it
seems sufficiently evident that they are produced by a meta-
morphosis of the hematin of the blood-discs; and it is by no
means improbable that the crystals consist of nothing more
than the altered colouring matter of effused and stagnant
blood. Similar crystals have been described by Kolliker in
specimens of effused blood, in the blood of the portal vein,
and in the spleen; and by Dr. Parkes and others in putrid
blood. They are interesting as exhibiting the crystallization
of a purely organic principle within the living and healthy
body.—Puitie B. Ayres, M.D., London.

‘ >
(ey oR)
re

Fig. 1 represents cells from the margin of the placenta of the bitch,
containing blue and reddish-brown colouring matter, often in granules ;
but these have neither the diameter nor appearance of blood discs. 400
diameters.

Fig. 2. Crystals contained in the tissues of the margin of the placenta
of the bitch, but not enclosed in cells, having a yellowish or reddish tint
under the microscope. 400 diameters.

Fig. 8. Vibriones from putrescent urine, showing the transverse lines
which indicate spontaneous divisions. 600 diameters.

All the figures were drawn with the camera lucida.

Vibriones.—Whenever an animal fluid, or water containing
a portion of animal substance, is allowed to stand aside for a
few days, until putrefaction commences, a multitude of minute,
active animalcules, of an elongated cylindrical form, may be
seen moving through it, which have received the name of
Vibriones. ‘lhese animalcules are so minute and transparent,
that no internal structure can be seen with a power of 600 or
900 diameters ; the highest powers with which I have had the
opportunity of observing them.. They have been viewed by

MEMORANDA. 301

some naturalists as the efficient agents or excitors of putre-
faction, in the same sense that the yeast-plant is the excitor of
fermentation in saccharine fluids; but this opinion is not as
yet decisively determined, although the experiments of Pro-
fessor Schultze, and, so far as I have been able to observe, their
universal presence in putrescent fluids, seem to corroborate
it. Considerable difference is seen in the length of different
individuals, some being as long as 1-600 of an inch, while
the shortest is 1-6000, the average length being 1-4000 to
1-2000. Although the variation in length is so great, all
of them retain nearly the same transverse diameter, which
is under 1-12,000 of an inch. This circumstance, together
with the immense rapidity of their formation in a putrefying
fluid, points to a fissiparous mode of reproduction; but this,
so far as I have been able to ascertain, has not been described.
In examining some putrescent urine last year, in which there
were a large number of these animalcules, I observed that,
while the shortest of the vibriones were in active motion, the
longer ones were comparatively quiescent; and that these ex-
hibited, according to their length, from one to six transverse
lines, indicating the points of separation in the reproductive
process. Those of moderate length, presenting only one or
two transverse lines, were rather active, and often bent at an
angle at the transverse line, which presented the appearance
of separation into two distinct individuals, and the character
of the movements appeared such as to favour the separation.
Those with from three to six transverse lines were, for the
most part, quiescent. I imagined, although from their ex-
cessive minuteness and transparency this was not plainly and
unequivocally discernible, that there were indentations of the
extremities of the transverse lines by which constrictions were
produced, which by their increase would finally effect a com-
plete transverse division of the animal (Fig. 3). These animal-
cules deserve a careful examination by those microscopists who
possess higher powers, on account of their intimate connexion
with the process of putrefaction.—Puitie B. Ayres, M.D.,
London.

Finder.—Observing in the last number of the Quarterly
Journal, an ingenious Finder for microscopists, suggested by
Mr. Tyrrell, I send a plan I have used some time for the
same purpose, adapted for minute objects and high powers.
On the thinnest writing paper, in a space one inch long and
half an inch deep, I rule about 30 divisions to the inch,
vertically, leaving on the top space to designate the numbers
of the lines ; this slip so ruled, I fasten with Rotham’s India

302 MEMORANDA.

Rubber Paste on the left side of the sliding object plate (fig.
a), with the bottom of the lines close to the lower ledge used
for the support of the object slide, &c.; I also rule another
paper one and half inch long, and one inch deep, with hori-
zontal lines also about thirty to an inch, numbering them on
each side as above, and paste the paper soruled on the bottom
of the brass piece of the stage (B) on which the slide moves,

so that the slide will pass over the paper, and cutting out a
half circle in the paper for the hole in the under plate, leaving
lines on each side the said hole. When I wish to fix the
finding of any minute object, I adjust the moveable stage
exactly square, by a mark made for the purpose on the upper
and lower parts (slips of paper pasted on each will do), and find
the object by moving the slide plate and slip of glass on which
the object is placed, till the latter is in the centre of the eye-
piece, and then observe the number of the line the left hand
end of the glass slip touches on the vertical scale, and also the
number of the line the bottom of the sliding plate rests on in
the horizontal scale—say No. 7 the first, and 15 the latter—I
then mark on the right hand end of slide or glass slip 7 and
15, and when so placed again the object is easily found. It
is very requisite, however, the stage should always be adjusted
to the mark before the left hand end of the slide or slip and
the bottom of the sliding plate are placed according to the
numbers. The above scales are easily made, and affixed to
every microscope with a sliding plate, or may be engraved on
the plate at a small expense. By placing these scales at
right angles to each other on a plain stage, the same end
may be attained, and in a simpler manner,—E. G. Wricut,
Hereford.

The Finder. —1 take the liberty of submitting to your
notice a modification of Mr. Tyrrell’s useful instrument the

MEMORANDA. 303

“‘ Finder,” adapted for use on the plain stages of foreign or
other microscopes. It gives at a glance, as you will see, the
latitude and longitude, so to speak, of the object sought, and
saves an infinity of time and trouble in hunting over uneven
surfaces—such, for instance, as fragments of flint containing
Xanthidia, where ordinarily the focal adjustments are con-
stantly at work.

Take a thin, flat piece of boxwood, one inch and a
quarter broad, and four incheslong. Along
the top of this fasten another piece,
thicker than your slides, a quarter of
an inch broad, and also four inches long.
Next, to the left side glue a piece of the
same thickness and one inch square, and
upon this a scale is to be ruled, divided
into fortieths of an inch, each mark repre-
senting a letter of the alphabet. Now
remove the middle inch from the three
that remain uncovered of the flat piece, as
far as the upper shoulder. Next take a
very thin slip of ivory, about a quarter of
an inch broad, and two inches and three
quarters long, point one of its ends, and
bore a hole for a pivot five-eighths of an
inch from the apex ; at the other end mark
an inch scale into fortieths, and number
the divisions by fives. This slip is to turn
on its pivot near the right hand edge of
the raised portion to the left, in such a
manner that its own scale may mark the
longitude in numbers of any object in the
field, while its pointed end will give the latitude on the
lettered scale of the boxwood.

The exact position of the object (+) in the accompanying
sketch is L. 22. he letters A, F, K, P, U, are used to every
long fifth line ; the shorts indicate the intervening letters. —
Tuomas Epwarp Amyot, Diss, Norfolk.

The Finder.—Since reading the description of Mr. Tyr-
rell’s “‘ Finder,” given in the last number of the Microscopical
Journal, I have adopted a modification of it which is far more
simple, and appears to possess several advantages over a sepa-
rate scale. My plan is to make a fine scratch, either with a
writing diamond or the broken end of a three-square file, near
the edge of the slide, directly opposite to the specimen of
which it is desired to preserve the exact locality, so as to be
able to find it again at any future moment. The method of

304 MEMORANDA.

using this is the same as in the original, with this exception,
that, instead of being bothered with counting the intermediate
divisions of the scale, the edge of the slide being brought into
the field, it may be moved horizontally until the scratch be
seen, and by using the vertical movement the object itself is
soon discovered. Of course, several objects may be thus de-
noted in the same slide, as both edges may be marked with
several lines each, and which may be so faint as not to disfi-
gure the slide in appearance. In recording on the label each
individual thus indexed, either end of the name may have the
number of the mark placed to correspond with that edge of
the glass which contains it.

To prepare the slide thus is extremely simple and easy.
In the first place a fine notch must be cut on the inner edge
and near the middle of the cross bar at the bottom of the stage
plate, and against which the glass slide rests when pressed in
its place by the “ clip:” let this notch be brought into the
centre of the field and the vertical movement alone be made
use of. For the horizontal, the slide itself must be moved
upon the stage plate until the desired specimen be found: then
bring the notch upon the bar again into the field, to see that
the two, the object and the notch, may both be in the centre
of the field, using the vertical movement on the sliding plate
of the stage. If the slide be held firmly by the clip (I use a
piece of cork in preference to a metallic spring), the plate
may be slid off and then marked with the greatest accuracy.

I have objects which may thus be readily found with a
quarter-inch object glass, and when once carefully marked the
slides are available at all times or with any instrument, and
are far more convenient in every respect,-as well as less un-
sightly, than when the discs are disfigured by rings scratched
or painted on the surface.—W. K. Brineman, Norwich.

Professor Riddell’s Binocular Microscope.— Your April
number, I perceive, contains some notice of my binocular
microscope, &c., from Silliman’s Journal. I have completed
two elaborate models of this instrument, both of which work
to admiration. I enclose you a printed slip from the April
number of the New Orleans ‘ Monthly Medical Register,’ from
which you may get an idea of my latest modification :—

Professor Riddell, the original inventor of the binocular microscope,
exhibited and explained a simplification of that important instrument, by
which, at an expense not necessarily exceeding thirty or forty dollars, it
is practicable, in existing compound microscopes of the ordinary forms, to
replace the brass tube carrying the ocular and objective, by an efficient
arrangement for binocular vision. ‘l'o accomplish an equal division of the
pencil of light immediately behind the objective, and to effect its distribu-
tion to each ocular, only two glass prisms need be used. They must be
of such form, that the faces, at which the light is immergent and emergent,

MEMORANDA. 305

shall form equal angles with the face on which the internal reflection
occurs. The chromatic dispersion is a minimum, and really nothing,
when these angles are each near eighty-seven degrees. This form is
theoretically preferable. In the instrument constructed, and shown by
Professor Riddell, the French rectangular prisms, such as sold by most
opticians, were used, in which the equal angles alluded to are forty-five
degrees. The long sides of these, which are the reflecting surfaces, face
each other, and, while the edges next the objective are in contact, the upper
edges are adjustable, so as to vary at pleasure the inclination of the prisms
to each other. In its transit through these prisms, the light is reflected
internally, and undergoes two refractions which are almost mutually com-
pensatory. The result is satisfactory. To produce orthoscopic binocular
vision, simple, not erecting eye-pieces, are required.

While making microscopical dissections, it is convenient
to have the free use of both hands. This convenience | com-
mand by connecting the fine focus movement with a delicate
piston-rod, which is moveable by breathing through a flexible
tube. This plan works admirably.—J. L. Rippert, New
Orleans, May 25, 1853.

Localities of Microscopic Plants and Animais.— For the
information of microscopical observers resident in and near
the metropolis, allow me to state that the following species,
in addition to commoner ones which I do not think it neces-
sary to specify, may be found in the freshwater and brackish
ditches in the parish of Milton-next-Gravesend :—

Surirella striatula Synedra Ulna
Gemma Amphora ovalis
Aneurea squamata Cymbella Ehrenbergii
striata Cyclotella Kutzingiana
Nitschia reversa Gomphonema olivaceum
Closterium Bacillaria paradoxa
Gallionella nummuloides Leucophrys patula
Cosmarium crenatum Coleps hirtus
undulatum Nassula elegans
Synedra valens Schizonema
biceps Euplotes Charon
acicularis ————- truncatus
—— radians Pleurosigma Hippocampus
lunaris — elongatum.

On the north side of the Serpentine, Hyde Park, especially
near the bridge, may be found :—

Cymbella maculata Amphora ovalis
Gomphonema cristatum Cocconeis placentula
Scenedesmus quadricauda Uvella hyalina

obliquus Gallionella nummuloides
Ankistrodesmus falcatus Euastrum elegans
Pediastrum Heptactys Pyxidula operculata.
Cocconema lanceolatum J. M. R.

Microscope Camera.—In the last number of this Journal,
I suggested an arrangement (fig. 12) for taking photographs
of microscopic objects. Since then I have perfected this ;

306 MEMORANDA.

and as it is very compact, steady, and ever ready for imme-
diate use, I think it may be found advantageous to those who
are constantly employing photography in its application to the
microscope. A tube, A, screws into the flange of a camera
which has a range of twenty-four inches; the front of this
tube is closed, and into it screws the object-glass, Bb. Over
A slides another tube, C; this is closed by a plate, D, which
extends beyond the upper and lower circumference of C, and
carries a small tube, E, on which the mirror, F, is adjusted.
To the upper part of D the fine adjustment G is attached ;
this consists of a spring wire coil acting on an inner tube
to which the stage-plate, H, is fixed, and is regulated by a
graduated head, K, acting on a fine screw likewise attached
to the stage-plate, after the manner of Oberhauser’s micro-
scopes. An index, L, is fixed opposite the graduated head,
K. The stage and clamp slides vertically on H, and by
sliding this up or down, and the glass object-slide horizon-
tally, the requisite amount of movement is obtained to bring
the object into the field. The object being brought into view,
the image is roughly adjusted on the focussing-glass by sliding

C on A; the focussing is completed by aid of the fine ad-
justment, G, K, and allowance then made for the amount of
non-coincidence between the chemical and visual foci of the
object-glass. The difference in each glass employed should
be ascertained by experiment in the first instance, and then
noted. By employing a finely-ground focussing-glass greased
with oil, this arrangement forms an agreeable method of
viewing microscopical objects with both eyes, and is less
fatiguing. As a very large field is presented to the observer,
this arrangement might be advantageously employed for class
demonstration.— Samuev Hieutey, Jun., Fleet Street.

PROCEEDINGS OF SOCIETIES.

Roya InstiruTion oF GREAT BRITAIN.

A Lecture on the Identity of Structure of Plants and Animals
By Tuomas H. Huxtey, Esq., F.R.S.

Tue Lecturer commenced by referring to his endeavours last year
to shew that the distinction between living creatures and those
which do not live, consists in the fact, that while the latter tend to
remain as they are, unless the operation of some external cause effect
a change in their condition, the former have no such inertia, but
pass spontaneously through a definite succession of states—different
in kind and order of succession, for different species, but always
identical in the members of the same species.

There is, however, another character of living bodies— Organiza-
tion ; which is usually supposed to be their most striking peculiarity,
as contrasted with beings which do not live: and it was to the
essential nature of organization that the Lecturer on the present
occasion desired to direct attention.

An organized body does not necessarily possess organs in the
physiological sense—parts, that is, which discharge some function
necessary to the maintenance of the whole. Neither the germ nor
the lowest animals and plants possess organs in this sense, and yet
they are organized.

It is not mere external form, again, which constitutes organiza-
tion. On the table there was a lead-tree (as it is called) which, a
mere product of crystallization, possessed the complicated and
graceful form of a delicate Fern. Ifa section were made of one of
the leaflets of this tree, it would be found to possess a structure
optically and chemically homogeneous throughout.

Make a section of any youag portion of a true plant, and the
result would be very different. It would be found to be neither
chemically nor optically homogeneous, but to be composed of small
definite masses containing a large quantity of nitrogen, imbedded
in a homogeneous matrix having a very different chemical compo-
sition—containing in fact abundance of a peculiar substance— Cel-
lulose.

The nitrogeneous bodies may be more or less solid or vesicular—
and they may or may not be distinguished into a central mass
(nucleus of Authors) and a peripheral portion (Contents, Primor-
dial utricle of Authors)—on account of the confusion in the existing
nomenclature, the Lecturer proposed the term ndoplasts for
them.

The cellulose matrix, though at first unquestionably a homoge-
neous continuous substance, readily breaks up into definite portions

308 PROG .EDINGS OF SOCIETIES.

j
surrounding each Endoplast,—and these portions have therefore
conveniently, though, as the Lecturer considered, erroneously, been
considered to be independent entities under the name of Cells :—
these, by their union, and by the excretion of a hypothetical inter-
cellular substance, being supposed to build up the matrix. On the
other hand, the Lecturer endeavoured to shew that the existence of
separate cells is purely imaginary, and that the possibility of break-
ing up the tissue of a plant into such bodies, depends simply upon
the mode in which certain chemical and physical differences have
arisen inthe primarily homogeneous matrix, to which, in contra-
distinction to the Endoplast, he proposed to give the name of Peri-
plast or Periplastic Substance.

Tn all young animal tissues the structure is essentially the same,
consisting of a homogeneous periplastic substance with imbedded
Endoplasts (zaclei of Authors) as the Lecturer illustrated by refer-
ence to diagrams of young Cartilage, Connective Tissue, Muscle,
Epithelium, &c, &c.; and he therefore drew the conclusion that
the common structural character of living bodies as opposed to those
which do not live, is the existence in the former of a local physico-
chemical differentiation ; while the latter are physically and chemi-
cally homogeneous throughout.

These facts, in their general outlines, have been well known since
the promulgation, in 1838, of the celebrated Cell-theory of Schwann.
Admitting to the fullest extent the service which this theory had
done in Anatomy and Physiology, the Lecturer endeavoured to
shew that it was nevertheless infected by a fundamental error,
which had introduced confusion into all later attempts to compare
the vegetable with the animal tissues. This error arose from the
circumstance that when Schwann wrote, the primordial utricle in
the vegetable-cell was unknown. Schwann, therefore, who started
in his comparison of Animal with Vegetable Tissues from the struc-
ture of Cartilage, supposed that the corpuscle of the cartilage cavity
was homologous with the “ nucleus”’ of the vegetable cell, and that
therefore all bodies in animal tissues, homologous with the cartilage
corpuscles, were “nuclei.” The latter conclusion is a necessary
result of the premises, and therefore the Lecturer stated that he
had carefully re-examined the structure of Cartilage, in order to
determine which of its elements corresponded with ‘the primordial
utricle of the plant—the important missing structure of which
Schwann had given no account—working subsequently from Carti-
lage to the different tissues with which it may be traced into direct
or indirect continuity, and thus ascertaining the same point for
them.

The general result of these investigations may be thus expressed :
—AInall the animal tissues the so-called nucleus (Endoplast) is the
homologue of the primordial utricle (with nucleus and contents)
(Endoplast) of the Plant, the other histological elements being
invariably modifications of the periplastie substance.

Upon ‘this view we find that all the discrepancies which had
appeared to exist between the Animal and Vegetable Structures

PROCEEDINGS OF SOCIETIES. 309

disappear, and it becomes easy to trace the absolute identity of plan
in the two,—the differences between them being produced merely
by the nature and form of the deposits in, or modifications of, the
periplastic substance.

Thus in the Plant, the Endoplast of the young tissue becomes a
‘primordial utricle,” in which a central mass, the ‘ nucleus,” may
or may not arise ; persisting for a longer or for a shorter time, it
may grow, divide and subdivide, but it never (?) becomes metamor-
phosed into any kind of tissue.

The periplastic substance follows to some extent the changes of
the Endoplast, inasmuch as it generally, though not always, grows in
when the latter has divided, so as to separate the two newly formed
portions from one another ; but it must be carefully borne in mind,
though it is a point which has been greatly overlooked, that it
undergoes its own peculiar metamorphoses quite independently of the
endoplast.—This the Lecturer illustrated by the striking case of the
Sphagnum leaf, in which the peculiarly thickened cells can be shewn
to acquire their thickening fibre after the total disappearance of the
primordial utricle,—and he further quoted M. von Mdéhl’s observa-
tions as to the early disappearance of the primordial utricle in woody
cells in general,—in confirmation of the same views.

Now these metamorphoses of the periplastic substance are two-
fold: 1, Chemical ; 2, Morphological.

The Chemical changes may consist in the conversion of the
cellulose into xylogen, &c., &c., or in the deposit of salts, silica, &c.
in the periplastic substance. Again, the periplastic substance
around each Endoplast may remain of one chemical composition, or
it may be different in the outer part (so-called intercellular sub-
stance) from what it is in the inner (so-called cell-wall).

As to Morphological changes in the periplastic substance, they
consist either in the development of cavities in its substance—
tacuolation (development of so-called intercellular passages) or in
Jibrillation (spiral fibres, &c.).

It is precisely the same in the Animal.

The Endoplast may here become differentiated into a nucleus and
a primordial utricle (as sometimes in Cartilage), or more usually it
does not—one or two small solid particles merely arising or existing
from the first, as the so-called ‘‘ nweleoli ;’—it persists for a longer
or shorter time ; it divides and subdivides, but it never (except per-
haps in the case of the spermatozoa and the thread-cells of Medusee,
&e ) becomes metamorphosed into any tissue.

The periplastic substance, on the other hand, undergoes quite
independent modifications. By chemical change or deposit it ac-
quires Horn, Collagen, Chondrin, Syntonin, Fats, Caleareous Salts,
according as it becomes Epithelium, Connective Tissue, Cartilage,
Muscle, Nerve, or Bone, and in some cases the chemical change
in the immediate neighbourhood of the endoplast is different from
that which has taken place exteriorly,—so that the one portion
becomes separable from the other by chemical or mechanical means ;
—whenee, for instance, has arisen the assumption of distinct walls

VOL, I. e

310 PROCEEDINGS OF SOCIETIES.

for the bone-lacune and cartilage-cavities; of cell-contents and of
-intercellular substance as distinct histological elements.

The Morphological changes in the periplastic substance of the
animal, again, are of the same nature as in the plant :—Vacuolation
and Fibrillation (by which Jatter term is understood, not only the
actual breaking up of a tissue in definite lines, but the tendency to
do so)—Vacuolation of the periplastic substance is seen to its
greatest extent in the ‘¢ Areolar” connective tissue ;— Fibrillation
in tendons, fibro-cartilages, and muscles.

In both Plants and Animals, then, there is one histological ele-
ment, the Endoplast, which does nothing but grow and vegetatively
repeat itself; the other element, the periplastic substance, being the
subject of all the chemical and morphological metamorphoses, in
consequence of which specific Tissues arise. The differences be-
tween the two kingdoms are, mainly, 1. That in the Plant the
Endoplast grows, and, as the primordial utricle, attains a large
comparative size ;—while in the Animal the Endoplast remains
small, the principal bulk of its tissues being formed by the peri-
plastic substance ; and, 2, in the nature of the chemical changes
which take place in the periplastic substance in each case. This
distinction, however, does not always hold good, the Ascidians
furnishing examples of animals whose periplastic substance contains
cellulose.

‘The Plant, then, is an animal confined in a wooden case, and
Nature, like Sycorax, holds thousands of ‘ delicate Ariels’ impri-
soned within every Oak. She is jealous of letting us know this, and,
among the higher and more conspicuous forms of Plants, reveals
it only by such obscure manifestations as the shrinking of the Sen-
sitive Plant, the sudden clasp of the Dioncea, or, still more slightly,
by the phenomena of the Cyclosis. But among the immense variety
of creatures which belong to the invisible world, she allows more
liberty to her Dryads; and the Protococci, the Volvox, and indeed
all the Algz, are, during one period of their existence, as active
as animals of a like grade in the scale. True, they are doomed
eventually to shut themselves up within their wooden cages and
remain quiescent, but in this respect they are no worse off than
the Polype, or the Oyster even.”

In conclusion, the Lecturer stated his opinion that the Cell-
theory of Schwann consists of two portions of very unequal value,
the one anatomical, the other physiological. So far as it was
based upon an ultimate analysis of living beings and was an ex-
haustive expression of their anatomy, so far will it take its place
among the great advances in Science. But its value is purely
anatomical, and the attempts which have been made by its author,
and by others, to base upon it some explanation of the Physiolo-
gical phenomena of living beings by the assumption of Cell-force,
Metabolic-force, &c. &c., cannot be said to be much more philo-
sophical than the old notions of ‘* the actions of the vessels,” of
which physiologists have lately taken so much pains to rid them-
selves,

PROCEEDINGS OF SOCIETIES. 311

** The living body has often, and justly, been called, ‘ the House
we live in;’—suppose that one, ignorant of the mode in which a
house is built, were to pull it to pieces, and find it to be composed
of bricks and mortar,—would it be very philosophical on his part
to suppose that the house was built by brick-force? But this is
just what has been done with the human body.—We have broken
it up into ‘ cells,’ and now we account for its genesis by cell-force.”

(T. H. HJ

MIcROscoPiIcAL SOCIETY.

April 27, 1853. George Jackson, Esq., President, in the
Chair.—A communication from Professor Wheatstone on ‘ The
Binocular Microscope, and on Stereoscopic Pictures of Microscopic
Objects’ was made by Dr. Lankester. (See Transactions in present
Number of Journal.)

May 25,1853. The President in the Chair.—A communica-
tion was made by Mr. Wenham on ‘ The Construction of Binocular
Microscopes.” He exhibited an instrument constructed under his
direction by Messrs. Smith and Beck (whose promptness to execute
the work he acknowledged) consisting of one object glass and two
eye-pieces, in which the object was presented stereoscopically to the
eye. This arrangement was effected by allowing the object to be
refracted through two glass prisms so as to reach separately the two
eye-pieces.

Mr. Shadbolt read a paper on ‘Some new forms of Diatomacee
from Port Natal.’ Having alluded to the confused state of the
nomenclature of the Foreign species of this family, and expressed a
hope that the work now in course of publication by Messrs. Smith
and Beck on the British species would lay the foundation for a more
correct system, the author proceeded to describe particularly the
novelties in a gathering from Port Natal, which contained no less
than fifty-five species, of which twenty at least were new, including
five of the genus Triceratium, two of Pleurosigma, and three of a
new genus Bacteriastrum. From the nature of the forms it was
concluded that the locality must have been subject to marine influ-
ence, and probably contiguous to some river.

June 22,1853. The President in the Chair.—Mr. Legg com-
municated to the Society some ‘ Observations on the Examination
of Sponge Sand, with Remarks on Collecting, Mounting, and
Viewing Foraminifere.’ Having observed that there was some
dezree of uniformity in the magnitude of several of the species of
shells, the author assumed that by sifting the sand through sieves of
different degrees of fineness much labour might be spared, and he
therefore procured some pieces of wire gauze, varying from 10 to
100 wires to the inch, the result of which was fully equal to his ex-
pectation, many of the larger kinds being thus brought together in
considerable abundance, and the mass cleared of 19-20ths of very
fine material, containing a very small proportion of shells; this

312 PROCEEDINGS OF SOCIETIES.

Jast-mentioned material was afterwards submitted to a process of
washing by placing a quantity of the sand in a dish, covering it
with water to the depth of half an inch, and gently agitating it so
as to form little eddies, the minute shells were then found to be
collected in distinct channels of a whiter aspect than the other parts,
and were readily removed by means of a camel’s-hair pencil.

The author then noticed the occurrence of Foraminiferous shells
on the Smallmouth Sand, near Weymouth, in considerable abund-
ance, by having remarked that the surface of the sand was distinctly
marked by little ridges extending many yards in length, and parallel
to the edge of the water; these portions, upon examination, proved
to be minute shells. He also mentioned the occurrence of Fora-
miniferz on the surface of the mud in Shoreham Harbour, and in
the ouze from the Oyster-beds. From these evidences the author
concluded that the surface alone of sand or mud banks should be
collected with a view to finding these organisms.

The paper concluded with some practical remarks on mounting
and viewing Foraminifere, in which the author recommended the
annular condenser of Mr. Shadbolt, or the parabolic reflector of
Mr. Wenham, as the best means of developing such of these objects
as are of a transparent texture.

A paper was read from Mr. Rainey on a new mode of illumi-
nating objects.

The President announced that arrangements had been made with
the Editors of the Microscopical Journal, by which the members

would be entitled to that publication without further payment as
heretofore. :

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DESCRIPTION OF PLATE X.

. Lateral aspect of the Faujasina. Magnified 30 diameters.
. Superficial section of the flat base of the shell. Mag. 60 diameters.
. Horizontal section parallel to the last, across the points 0 8, in fig. 1.

Mag. 60 diameters. .

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

meters.

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DESCRIPTION OF PLATE V.
Fig.

1. Longitudinal section of superior canine tooth, exhibiting contour mark-
ings — their general arrangement. Slightly magnified.

2. Transverse section of canine tooth, decalcified and picked abroad, so
as to exhibit the annular (stratified) arrangement. Mag. 15 dia-
meters.

3. Transverse section of canine tooth, exhibiting globular patch, and the
various forms of interglobular spaces. Mag. 200 diam.

4. Innermost film of calcifying dentine, removed from the inner surface
of the pulp cavity of a molar, exhibiting calcified globules, and
interglobular uncalcified dentine, dried up. The specimen is
mounted in balsam. Mag. 200 diam.

. Similar to the last, from a bicuspid. This specimen exhibits the
calcification of tubeless dentine. Mag. 200.

on

DESCRIPTION OF PLATE VI.

Fig.

Z Represents a section of a portion of the scalp ae perpendicular to
the surface and parallel to the hairs.

@, Gy 4, » . . M, are muscles attached to the hair-folliclesbb6...
just below the sebaceous glandsecc .... andextending up to-
wards the epidermis, of which d is the corneous and e the mucous
layer ; ff is adipose tissue.

2 Exhibits on a larger scale the upper attachment of the two muscles a
and a, of fig. 1, a being the upper end of a,, and 6 that of ag; cis
the corneous and d the mucous layer of the epidermis.

3 Shows the insertion of the muscle a, of fig. 1 into its hair-follicle, a‘
being the lower end of a: the hair and follicle are cut across very
obliquely ; b is the hair slightly tilted out of the inner root-sheath
c, and dimly seen below through the transparent root-sheath in its
course downwards ; d is the outer root-sheath, e the “‘ structureless
layer of the hair-follicle,” / the circular coat of Kolliker, g the
longitudinal layer, 4 is part of a sebaceous follicle, 7 is some of
the fibrous tissue of the dermis.

4 Represents the upper termination of a muscle } c with the surroninhee
fibrous tissue of the scalp gelatinized by acetic acid ; a b is the free
surface deprived of epithelium.

5 Exhibits characteristic nuclei, highly magnified, from a muscle con-
nected with a hair-follicle of the pubes,

6 Shows the appearance of a portion of a muscular fasciculus, from the
areola mammz, after the addition of acetic acid; the rod-shaped
nuclei are seen to lie in an indistinctly fibrous stroma.

VOL, I. Z

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<<

TRANSACTIONS

MICROSCOPICAL SOCIETY

LONDON.

NEW SERIES.

ee

VOLUME I.

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

rage tre Mig o's
i ae
& vier (oth,

ety 2 2.

at AB sy

ha See

aa i F FT

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, 3.

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

93 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 Mvll, Prof. W. Gregory,
92.

K.

Eleagnus pee et raphides in, 22.

Epithemia turgida, 95.

Eunotia Triodon, 95.

», Pentodon, 95.
55) abr, 95.

F.

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

Fresh-water Algz, 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 Lacinularia so-
cialis, 1. ;
Hydrodictyon utriculatum, amyla-

ceous corpuscles of, 67.

K.

K6lliker on division of the yolk in
Megalotrocha, 11.

| bs
Lacinularia — socialis, gees and
physiology of, by T. H. Huxley,

F.R.S., 1.
Leydig, Anatomie u. Entwick.-gesch
d. Lacinularia socialis, &e., 2, 8, 12.
Lyngbya floccosa, 71.

M.

Megalotrocha, 1, 12.

Melicerta, 2.

Merulius lachrymans, 74.

Mesostomum, 7.

Mesocarpus scalaris, 71.

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

Mull earth, 95.

Index to Transactions.

N.

Naviculacez, 93.
Notommata aurita, teeth of, 4.
water vascular sys-
tem in, "P. H. Gosse on, 5.
Nonionina, 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.

5 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,

Ss.

Scilla maritima, vaphides 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 Asteridie or |
stellate bodies occurring in the cells |
of Fresh-water Algz, 68.

Spharoplea 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.

Abe

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.

MV.

Volvox globator, Busk, G., on the struc-
ture and development of, 31.
= 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 Volvox
globator, 45.

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

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

Z.

Zygnema quadratum, 70,
» gquintnum, 70.

TRANSACTIONS

OF THE

MICROSCOPICAL SOCIETY

OF

LONDON.

LactNubariA socrAus. A saga to the Anatomy and
Fg logy of the Rortrera. y DE Hoxrey, Mea,
F.RS., Assist.-Surgeon R.N. (Road 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. Miiller bestowed upon it
the name of Vorticella socialis, which was changed by
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. L

2 Houxtey 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 Lacinularie 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, 5), 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 (f).

Anatomy of Lacinularia.—I 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. ] and 2; from above
at fig. 3. 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 Lacinularie ever do leave the gelatinous envelope
of the parent mass, unless aggregated together,

+ Leydig (Zur Anatomie und Entwickelungs-geschichte der Lacinu-
lavia socialis—Siehold 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.”

ie

Hox ey on Lacinularia socialis. 2

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 the 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 cesophagus. 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 (I. 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 Huxtey 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 Lacinularia “reihenzihnigen,” that is,
having a stirrup-like frame, with many. teeth set upon it's
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, conyex 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 cesophagus 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 opens 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 coeca,

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 twa
larger, and they do not open into the alimentary canal.—Loe, cit., p, 463.

~-

Huxtey on Lacinularia secial’s. 5

lular cceca 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 )

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 obyvious,{ 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-laippchen),
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. Riiderthiere-—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 Notommata 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.”—Leydig, loc. cit., p. 463.
7 “Sehr aus-gepragt,” 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 the
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 cceca. 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 dise infra) ; that from these,
vessels proceed to the central glands (vacuolar substance, in which the
“band” of the water-vascular system terminates, mii), 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. ¢., ,
p- 465.

Hoxcey on Lacinularia socialis. 7

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 I 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 (Beitrige zur Naturgeschichte d, Turbellarien).
Through these the transition to the richly ciliated water-
vessels of the Naida, &c., is easy enough.

Vacuolar Thickenings—(figs. 2, 3 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 Lacinularia 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 Hux ey on Lacinularia socialis.

developed many clear spaces, or vacuola—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, 87) in the trochal dise 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-yascular
system terminates.

According to Professor Ehrenberg these are all ganglia,
and the two yellowish bilobed or cordate bodies en 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 Ehrenberg
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 ganclion 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 Bra-hionus 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.

Huxiey on Lacinularia socialis. 9

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 7) (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 Nemertidaw, 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 Amphioxus.

Mr. GosSe has described a similar organ in WMelicerta
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 is 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 Hux ey on. Lacinularia soctalis.

“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 calear 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.* The 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. c., 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.

Houxtey on Lacinularia socialis. 11

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—l, 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 Kélliker 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 foetuses 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 Lacinularia, 1-30th 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 Houxtey 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 ovarium, 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 deserip-
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 Kdélliker again, these bodies are found only in
those animals which possess ova undergoing the process of yolk
division, while I foundthem 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 latter 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 tertiwm 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 hitber 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-

Hux.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 K6lliker, Zeitschrift, 1850).

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

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,

A sexual 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 Rofifera, im various often irre-
gular forms: these have a much slower development, and I 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
closely resembling in size and form the heads of the spermatozoa of Laci-
nularia,

14 Hoxtry on Lacinularia socialis.

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 Notommata. 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 iden-
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 (1. 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,

Hoxtey on Lacinularia socialis. 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 Notommata, it appears, lasted for
some months without change (Dalrymple).

It is remarkable that jn 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 Lacinu/aria, 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 gemma.” 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.

16 Hextey on Lacinilaria 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 Stephanoceros 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, ‘Tur-
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 Moneecious Annelids, in Trematoda, in
Turbellaria, in Echinoderms, and perhaps in the Nema-
toidea.t

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

4, A somewhat similarly armed gizzard is found in the
Nemertide ; 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 larvae. 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.

i

Huxtey on Lacinularia socialis. ij

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.

Melicerta 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. I,

VOL, I. Cc

is Hoxtey on Lacinularia socialis.

In WV. 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-
57). 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 Flos-
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
he 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 moncecious 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. Miiller upon the Echinoderms,* I have
shown that the same proposition holds good of the latter in

* Annals of Natural History, 1851.

Hoxzey on Lacinularia socialis. 19

their larval state, and hence | 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 Medusx, 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 Asterias 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 Nemertide 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
Amnuloida; 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 31st 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 ina state of permanent conspiracy
against his views. df begets ig! :

July 9, 1852.

Qo

( ROR

On the Structure of the Rapuipes of Cactus ENNEAGONUS. By
Joun Quekettr, 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 imorganized.

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. ‘lhus, 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 | 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—in 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.

Quexerr on the Raphides of Cactus enneayonus. rH

Raphides were first noticed by 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 ora 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
ef 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 an 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
interior 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 poimted.
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 bemg 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 im 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 air-pump in
order in fill the cells with the fluid ; the paper was then dried,

Quexerr on the Ruphides 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 laminz of a brown colour ; others, as
in fig. 2, will exhibit a spot like a nucleus, first surrounded by
concentric lamina, but towards the margin the lamina 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 prisimatic 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 Quexertr on the Raphides of Cactus enneagonus.

acid, but I was much astonished to find that in many cases 2
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,
I 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 concentrie
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 lamina, 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 intt-
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

QuekettT 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 ina 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 Quexett 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 acid—oxaiate 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 oceur-
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, 1 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. 27

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 beimg 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. Besides 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 6.

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. It is 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. 1 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.

( 28)

On the Development of Tubularia indivisa. By J. B. Mum-
mMERY, 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 originating 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 appearance
shown in fig. 3, Pl. IV.

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 Medusa, 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 Zubularia, and that it undergoes no intermediate
metamorphosis, or alternation in its mode of existence; |
have thought it possible that the eight-armed creature might
prove a Medusoid.

( 31)

Some Observations on the Structure and Development of Vo.vox
GLOBATOR, and its relations to other unicellular Plants. By

Geo. Bus, Esq., F.R.S. (Read May 26, 1852.)

Turee 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 has also been described under the name of Spherosira
Volvoz.

As J 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 Ebrenberg, 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—in 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 Volvoz. With respect to
some points of structure, however, concerning which Professor
Williamson differs from the Prussian observ er, I am inclined,
from my own observations, to side with the latter, whowe
errors in the case of Volvoz 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 che 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
c omparison between him and the great and laborious Prussian
microsc opist, 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 ef Volvox globator,
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. At a 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 Volvox, termed V. aureus by Ehrenberg,
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 Volvox 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, under
the name of Spherosira volvox, also presents the appearance

Busk on Volvox globator. 33

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 embryes.

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 cel! 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-

d2

34 Busk on Volvox globator.

dergo segmentation, as pointed out in the case of Volvor—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
amore rapid ratio, up to a certain point, than the segmenta-
tion goes on, so that each segment of the still-dividmg 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 Volvor 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 Volvoxr, 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

Busx on Volvox globator. 35

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 Volvoz 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 side 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

Bus on Volvox globator 37

zoospore, when viewed from aboye, exhibits two highly refrac-
tive spots placed side by side, which seem 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 con-
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.

38 Busk 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 gelatinous 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.

5. 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.

Having thus traced one form of Volvozx through its course of
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 cloudiness is 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

Busk on Volvox globator. 39

other Alga—that it may, in fact, be termed the “ winter
spore” of Volvoxr, 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 Volvoxr 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 externa] 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 Volvor 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 Volvoz 1 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 Alge 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 Volvox, the ultimate result of the
segmentation constitutes numerous minute ciliated cells or
bodies (fig. 14)—not, however, as in that case, lining the

40) Bus 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 Syncrypta of Ehrenberg.

With respect to the chemical constitution of the above
deseribed parts, the following are the results at which I have
arrived :—1l. 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. 1 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

Busk on Volvox globator. 41

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.)

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 Volvox—upon which alone I think we are dis-
agreed—is essentially such as I have described it, viz., that it
is formed by a continuous, 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 amass of vegetable protoplasm, without dis-
tinct wall, and precisely analogous to a Euglena, or other
naked zoospores, but represents the endochrome of a cell hay-
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 Volvox, which formed
the subject of my paper, is sufficiently obvious. But it is
nevertheless true, as I find from examination of Professor Wil-
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 coiteal: green body i is sammanealeed 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 is 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 observed

Busx 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, is 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 Volvox 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 pm., Oct. 4. Fig. 22,
8 a.m., Oct. 5.)

Now with respect to the other form of hexagonal areo-
lation, for my knowledge of which, as I have stated, I am
chiefly indebted to Professor Williamson, and which is
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

d4 Busx ox 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, | 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 Volvozx while within the parent, and
in which also it is not I think 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-

Busx 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 which 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 Volvoz in which I
have noticed this have been preserved in glycerine for two

months.—G. B.]|

Further Elucidations of the Structure of VoLvox GLOBATOR.
By Professor W.C. Wittramson. (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 Volvox, 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 Wittiamson 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 Volvoz, 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, | 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-

Wittiamson 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-
ments 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 is
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 (6)'). As they 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

48 Wituramson 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
size, excepting at certain points where they remain in contact.
Before tracing out the further stages of this process I must
observe that the Volyox exhibits two apparently distinct states,
which are, nevertheless, mere varieties of one species. In the
one, each ‘protoplasm assumes the appearance of fig. 1 6, being
angular, and giving off thick, irregular and often dichotomous
threads (le), the extremities 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 correspofiding 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 1
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 areole, as repre-
sented in fig. 11, which is a faithful transcript of part of one
of these specimens when mounted in glycerme. In this ex-

Wiiamson on Volvoxr 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
bas 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; /aterally 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 c’) in variable conditions. Some-
times it forms an oval cell (14 c’), sometimes it is oval at one
end and flattened out at the other (14c, l5c’); 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. f

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 Volvox, even where the cells are viene we only

ea

50 Wittiamson 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 cell-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 imner protoplasmic membranes (7c) of the one with the
only membranes seen (17 ¢) 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-

Wictiamson on Volvox globator. 51

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 can 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.uiamson 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 gemme, as already observed, the protoplasms
are in close contact on all their sides ; but it 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 Ile, 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 haye
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-

Wituiamson 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. his
condition obviously indicates the existence of some invisible
point dappui, 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 Wittiamson 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 6), 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 Jatter 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. ‘lhe 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

Wittiamson on Volvox globator. 55

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 Infusorie 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 Algz 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 gemmz is in
progress that a real relation exists between Volvox and young
growing Conferve. At a later period every segment of the
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 Wittiamson 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 parent
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 Volvozx 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 J. stellatus the protoplasms were of
the stellate form of fig. 1. The investing cells were obviously present in
all the examples which I examined. 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. aureus are the true winter spores. In J. séellatus I
have noticed that the ordinary power of gemmation appears to have worn
itself out; since, though the gemmz often co-exist with the spores (?),
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 gemmz 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 gemmez 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.

Ca

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

Ar 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 producing. 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. £

D8 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, I 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. Buss, 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 Verjiipngung in der Natur.’

1851.
SF 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.
Braun (/. c.), however, supposes that this cavity does not eciot
originally i in the Sruntite! but that it is of a secondary nature,
arising in the disappearance of the nucleus.

Phe 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 of the essential constitution of
the granules.

In accordance with the former of these views, Muinter,*
Niigeli,t and Link, suppose that the laminz 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 (/. 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 4 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.

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

* Miinter, ‘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. 18, f. g. h.

§ Schacht, ‘ Die Pflanzenzelle.’ 1252, p. 41.

\| Leeuwenhoek, ‘ Epistole Physiologice,’ &c. Delphis. 1719, p. 2386:

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 Miinter 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 Leeawenhoeck, 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 iib. d. Mittheil. von Freunden d,.
Naturwissen. in Wien.” Mai—Oct. 1846. Wien, 1847, p. 84.

62 Busx 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 statch-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 imgenious 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
ofas 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 1 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, whichis 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 Busk on Starch-Granules.

microscope, and the object-glass (4 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 small 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

* L.c., p. 279.

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 rugee, 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 plice 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. VIIL.,
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 ; in consequence
of which inequality of tension the phenomena exhibited
under polarised light might be explained. 1 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, 38, 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
oneiend: of each grain is a minute circular spot, the area of
which appears otaniila® ; 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

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

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-grains 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 zine by dissolving | 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) 8 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 Situ 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
lies 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 1 have noticed in

the paper.

On the Stellate Bodies occurring in the Cells of FREsH-WATER
Autca. By the Rev. Wittiam Smitu, F.LS.

Tue third volume of the ‘Transactions of the Microscopical
Society,’ containing, at p. 165, et seg., two papers by G. Shad-
bolt, Esq., ‘On the Sporangia of some of the Filamentous
Fresh-water Algz,’ 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 Alga, which
this author has shown to be a true spore, each such body,
formed by the union of two cells, giving birth, upon germina-

9

oF

Smitu on Asteridia.

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., Pl. 1V. 5, V. 38, VI. 4). I 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,’
2dS8., vol. viii., p. 480), and have no hesitation in accepting the
facts as of general import in reference to the entire family. I
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. 1 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.

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 Aly@ 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. 1X., fig. 2 b,
fig. 4b, &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 calls 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 a 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 c assume
the character of perfect catenin: 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 Kiitzing
has done in his genus ynchonema, 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. Tt

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 8, 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 Queketr on Fungus.

Norte.—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 CRrYsTALLINE
Marrer in the Interior of a living Oak Tree. 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 greatly 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 accident; 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,

Quexetr 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. LX. 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. 50 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 ayerage 1-500th of an inch in diameter, whilst some of
the latter were 1-8th of an inch square ; most of the filaments

J

74 QuexketTr 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 cayity
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
as a 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 descrihed ; 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,

Quexkett 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.

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BE PO-n FE

OF
THE THIRTEENTH ANNUAL MEETING

OF THE

MICROSCOPICAL SOCIETY.

The Microscopical Society of London held their Thirteenth
Annual Meeting, February 11th, 1853,—Grorer 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. 73

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 W ednes-
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 economicai 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 adyerted 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
attracf, 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 Society. 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 Alge 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 his
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. 89

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. ‘I'he 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 50002. 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.
Prondeiy Eee ae GerorGE Jackson, Esq.
DCUSITET Fs on co da N. B. Warp, Esq.
Pg 0g lt et ae tae JoHN QUEKETT, Esq.

Assistant Secretary . . Mr. Jonn W1t.1ams.

New Members of Council.

W. Gittert, Esq.

Joun Ler, Esq., LL.D.
Rosert WarincTOoN, Esq.
F. H. Wenuay, Esq.

In the room of
M.S. Luce, Esq.
M. Marsuatt, Esq.
ALFRED Ros tine, Esq.
J. B. Smmonps, 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,

On the Minute Structure of a Species of Fausasina. By Pro-
fessor W. C. Witttamson. 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 g), 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 large
oral aperture (1 e). :

Along each of the vertical septal lines (1 @) 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 6 andd), but they do not occur in the peripheral margin
(1 f and 6 e), or in the spiral septum (fig. 2). 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 4). 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,
whilst 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 6), 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 conyolutions
(2c). 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, 6,
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

WILLIAMSON on Faujasina. 89

marked tendency to divide into two branches (fig. 3 a, b), one
of which is usually ina plane a little above the other. 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
conyolutions ; 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. (ue

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 5g). 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-

90 WILiiAMson on Faujasina.

tainly crossed the second one (see fig. 3), which is seen at a,
along with four others, 6, c, d, and e, 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. 5h’. Similar canals are
also seen at 5 hk, passing upwards into the inter-septal spaces ;
whilst at 5 72’, 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 anew 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 occur 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 between the
soft tissues inhabiting the spiral segments of the shell and those

WI LuiAMson 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. 66), 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. 6 6; 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 (bf), 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 (6).

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 memoir, 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 WILLIAMSON on Faujasina.

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

Tam 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 dead
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
Wittram 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 bya 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 tlie variety of forms, and resolved to study it
more closely ; this | 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 this
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
i acuminata a lata
= oblonga eb ciit alpina
35 viridis | Navicula serians
divergens 5 rhomboides
an acuta 5 ovalis
. | .
x radiosa ' m dicephala
os mesolepta a firma
fe interrupta <4 angustata
Tabellaria Gomphonema acuminatum

sibba + cruciatum

GREGORY on Diatomaceous Earth. 95

Gomphonema Vibrio Himantidium gracile, Kiitz.

55 capitulatum PA bidens, W. Sm.
Amphora oyalis ¥ pectinale, Kiitz.
Stauroneis Phcenicenteron i arcus, Kiitz.

és gracilis a major, W. Sm.
ee linearis a undulatum, Ralfs.
a anceps Tabellaria frustratay Ktitz.
Cymatopleura elliptica ; * ventricosa, Kiitz.
& apiculata Epithemia turgida
Cocconeis Thwaitesii an gibba
a Placentula Eunotia gracilis
Surirella Brightwellii » retrorsum
ss biseriata » Diadema
Cymbella Helvetica Synedra capitata
o maculata 5 biceps
ep sativa Fragillaria capucina, Kitz.
pee aitinis Orthoseira viridis, W. Sm.
5 cuspidata $3 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. 1 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. Smith did not meet with, are Melo-
siera distans, and possibly M. nummuloides; Hunotia
Triodon, and E. 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.

culacew, 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 Stauronetis
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 Eunotia
Tetraodon, E. Diadema, Himantidium Arcus, H. bidens, and
the 4 other Himantidia and Epithemia turgida. 4Athly. 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. 5thly. 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. 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 bis 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 striae, and it is 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 striae (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 stria
may be shown and counted, It is possible that this form

GREGORY 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 strie, and Mr. Smith thinks it must stand near
Eunotia Arcus, Kiitz.= Navicula Arcus, Ebr. 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 - - - - 15°04
Organic matter = - - - - - 12°36
Loss, chiefly water - - - ~ 1°85
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 Grecory 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 Graminez, &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-
diacee, such as Euastrum, Staurastrum, and Cosmarium; but
on these points I will not venture to assert anything, although,
as Desmidiacee 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

GreGorY on Diatomaceous Earth. 99

form in the Mull deposit. They are represented with
a power of 400 diameters. I
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, I had from Mr. Topping.
Himantidium Arcus, which, when small, has some slight
resemblance to the above form, has only 22 striz in 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,
Kiitzmg—Navicula Arcus, Ehr.; but that it cannot be referred
to that species. Indeed it is only very immature specimens
of FE. 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 ?

Fig.l.

SL

On the Binocular Microscope, and on Stereoscopic Pictures of
Microscopic Objects. By Professor C.“Wuratstong, F.RS.
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

100 WueEatstonE 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, J,
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. 'Thesmethod 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 suffi-
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 l’Objet. Par le P. Cherubin
@ 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 retina. 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

102 WuearstoneE 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.

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