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The Monthly Microscopical Journal, Jan¥ 1.1871.

Procris Statices.

Greenish Black, Red, 2 Blue

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THE MONTHLY
MICROSCOPICAL JOURNAL:

TRANSACTIONS

OF THE

ROYAL MICROSCOPICAL SOCIETY,
RECORD OF HISTOLOGICAL RESEARCH

AT HOME AND ABROAD.

EDITED BY

HENRY LAWSON, M.D., F.R.MS.,

Assistant Physician to, and Lecturer on Histology in, St. Mary’s Hospital,

VOLUME V.

LON Dp O.N :
ROBERT HARDWICKE, 192, PICCADILLY, W.

MDCCCLXXI.

SSE — eee
LONDON: PRINTED BY W. CLOWES AND SONS, STAMFORD STREET AND CHARING CROSS.

Monthly AMicvoscopical Journal, January 1, 1871.

CONTENTS OF No. XXV.

— 0+
ART. PAGE
I. Nore on FLUORESCENCE v. PSEUDO-DICHROISM. By
the late Rev. J. B. Reade, F.R.S., P.R.MLS. J % ie 1

Il. Notes on tHE Minute: Structure oF THE SCALES OF CERTAIN

Insects. By 8. J. McIntire, F.R.M.S. fl pi i) Sa

IiI..On an Oprican Innuston Sime: Cracks 1n Sinica Fitus. By

Henry J. Slack. F.G.S., Sec. R.M.LS. —.. - = zap whee

IV. Oxsect-cLassES AND THEIR Derinition. By F. H. Wenham,

Vice-President R.M.S. .. se ie ie an 16

V. On tHe Movuntine or THE DiAtom-prism. By F. W. Griffin,

PLD: és ee A AE i be 4 ix) leas

VI. On Preroprna vaLvata: A New Species. By C. T. Hudson,

LL.D. fe F Me es aA = Be fag ae
Procress oF Microscopical ScrENcE ns ee # i: ait oO
Notes anpD MemoranpDA 37
CorRESPONDENCE 38
PRocEEDINGS OF SOCIETIES .. 39

44

BrIBLioGRAPHY

The Monruty MicroscoricaL JouRNAL is furnished free to Members of the
Royal Microscopical Society. Non-Members can get it from any bookseller,
price 1s. 6d. per month.

Contributors must write their Names and Addresses on the first page of MS.

All Communications to be addressed to the Editor, 192, Piccadilly.

a

>

THE DEATH OF OUR PRESIDENT.

Ir is with the deepest grief that we have to announce
that our Presipent, the Rev. JosepH BANCROFT
Reape, M.A., F.R.S., F.R.A.S., is no more. On
Monday morning, the 12th of December last, he passed
from among us in the seventieth year of his age—
passed with regret that he should be compelled to leave
us, and yet with calmness, courage, and confidence in
the Future. Those who knew him throughout his long
and active life can say more of his many doings than
we can now—can record a career of noble activity.
But of his manly nature, his child-like simplicity, his
endearing disposition, his appreciation of those who

surrounded him, and his thorough kindliness of dis-

position, we cannot speak in terms too high; or be

even momentarily accused of leaning too deeply on the
many virtues of one whom, in common with all who
knew him, we mourn the loss of with a grief too deep
to be fully expressed. Hereafter his life will be told
by one who has loved him well, and who knew of all
that he had done and much that he had thought.
For the present we may say, as has well been said on
another occasion, the fewest words are best where all

words are Grief.

5 ee ms

Onis
RaW YGRK

BOTANICAL

Garpe®

THE

MONTHLY MICROSCOPICAL JOURNAL.

JANUARY 1, 1871.

I.—Note on FLUORESCENCE vy. PSEUDO-DICHROISM.
By the late Rev. J. B. Reapz, F.R.S., P.R.MS.
(Read before the RoyaL Microscopican Society, Nov. 9, 1870.)

At several meetings during the last three years I have exhibited
to the Society a coloured liquid, prepared by Mr. Sheppard from
fresh-water algae, species undecided, found in a spring in Kent.
An exactly similarly-coloured solution was described by Dr.
Ferdinand Cohn, of Breslau, in the number of Schultze’s ‘ Archiv,’
published about the same time, early in 1867.

The characteristic qualities of the English liquid will be found
detailed at length in a letter from Mr. Sheppard to myself, read
before the Society on the 8th of May, 1867; and I will here quote
Dr. Cohn’s description, which so exactly tallies with that of Mr.
Sheppard, that we may assume that the liquids are exactly similar,
and that the phenomena of colour are the same in both.

Dr. Cohn writes :—“ Another most startling optical peculiarity
of the Phycocyan is its fluorescence; for seen only by transmitted
light on a clear background, the Phycocyan appears indigo-blue ;
but with reflected light and a dark background it shows an intense
carmine red.” This account of the play of colour is exactly that
given by Mr. Sheppard, except that he compares the colour seen by
reflected light with that of the carnelian; and I think that this
simile is more exact than that of Dr. Cohn, seeing that the liquid
shows an opaque dull intense scarlet, rather than the bright trans-
parent crimson of carmine.

Now this phenomenon of fluorescence (for Dr. Cohn’s phrase
has been generally adopted) has attracted less attention than might
SShave been expected. Other solutions, for instance quinine, exhibit
_onfluorescence, or faint iridescent gleams of blue and pink; but in the
“ease of Phycocyan the violent change from all blue to all red by
*“altered illumination goes far beyond what is seen in any of these

chemical compounds, and leads one to believe that the one name
Fluorescence is not a proper description of the two sets of appear-
Q VOL. Vv. B

2 Transactions of the

ances. I hold the play of colour in the two cases proceeds from
two very different causes; and that this opinion is correct I shall
now be able to show by an experiment. I have here a bottle con-
taining water stained blue by a little indigo from my water-colour
paint-box: to this transparent blue liquid I have added a little
vermilion in impalpable powder ; and straightway I have obtained
all the fluorescent qualities of Phycocyan. That is, two colouring
matters, one opaque the other transparent, dissolved out of the
plant (according to another theory developed from the plant), are
represented in one artificial liquid by mdigo and vermilion. Now
hold the bottle to the light, the transparent indigo alone is visible,
the grains of vermilion showing only their shaded sides, which
appear grey or black by contrast with the strong light, and there-
fore, do but subtract a little brightness from the blue. Now change
the position of the bottle, and by so doing change the illumination ;
the “intensiv karminroth” of Cohn at once shows itself. The
transparent blue throws back no coloured rays, but the opaque red
particles are exhibited in quantity sufficient to make “the blue one
red” (Shakspeare). Seeing then that the fluorescence of quinine and
this fluorescence of Phycocyan spring from different causes, I think
it will be proper to distinguish them, and I propose for shortness
to name this play of colour described and exhibited to-night—
Pseudo-dichroism.

I am indebted to my friend Mr. Sheppard for the ingenious
experimentum erucis above described. It is the exact counterpart
of nature’s operation in the production of Phycocyan, which consists
of opaque red particles in a transparent blue flud. Thanks to my
friend for his solution of the mystery, and also for enabling me to
present this account of it for the consideration of our Fellows.

“Omne ignotum pro magnifico.”

But the mystery ceases when we know all about it.

BISHOPSBOURNE Rectory, Nov. 7, 1870.

Royal Microscopical Society. 3

I1.—Notes on the Minute Structure of the Scales of Certain Insects.
By 8. J. McInrme, F.R.MS.
(Read before the Roya MicroscopicaL Society, Nov. 9th, 1870.)
Puates LXIX., LXX., LXXI.

Dr. Picorr’s paper on High-power Definition has caused me to
devote some further attention to the markings of the scales of
insects ; and as some of the results I have obtained in the examina-
tion of a very great number of scales from all sorts of insects are
curious, it may be well to place them on record, since they may
prove as novel to a few readers as they were to me.

The first fig. on Plate LXIX. represents the scale of one of our
hunting spiders, Scenzcus salticus, the prettily-marked zebra-spider,
which has so often furnished a theme for natural history writers,
from its ingenuity in laying wait for and capturing its prey by an
accurate and sudden spring upon it—a process which may be easily
seen on any hot summer day on walls and palings fully exposed to
the sun. The scales are situated on all parts of its body and legs;
and with some care, though not without difficulty, they may be de-
tached and examined under high powers. Their margin is beau-
tifully crenated, and the outer membrane is smooth, while the inner
membrane—that is, the membrane next the spider’s body—is puck-
ered up into somewhat irregular rows of hackles. When I first found
this scale I was struck with its resemblance, though a distant one, to
the view which Mr. Beck entertained respecting the surface-contour
of the Podura scale (Lepidocyrtus). I could not help regarding it
as, to a certain extent, confirming his view that the “ interjection
markings” on that scale are elevations of the membrane. I am still
further strengthened in the notion since reading Sir John Lubbock’s
latest observations upon the position which the Thysanura occupy
in relation to entomological classification. It would appear, from
the absence of trachez in many of these creatures, the presence of
certain abdominal appendages (possibly representing extra legs),
the absence of metamorphosis, and some few other points, that this
authority is disposed to see in them a closer relationship to the
Arachnida and Myriapoda than to the Insecta. At all events, it
is clear that the peculiar hackle-hke structure, which has been
asserted for the Lepidocyrtus scale, is not without a parallel among
the tegumentary appendages of the Articulata.

Another very curious scale I found surrounding the eyes, and
various portions of the under-surface of one of the Chinese Curecu-
honide, Hypomeces squamosus.* This scale is leaf-shaped; its .

* It would perhaps be correct to consider these two scales as imitating the
structure of compound hairs.
B 2

+

i Transactions of the

surface is also hackled, somewhat like that of the spider-scale I
have alluded to, but to a much greater extent. Perhaps some will
regard it as plumose. It also presents the phenomenon so common
to many insect scales, of decomposing the light which passes through
it, so that some portions of its fringes display gorgeous colours by
transmitted light,—colours more or less complementary to those
seen in the same scale by reflected light.

In the scales of Polyxenus lagurus I have found what is very
uncommon (so far as my examinations, which have been very care-
fully made, are reliable), a deposit between the membranes. The scale
is a solid structure, not, as in the generality of cases, merely an upper
and lower membrane without any intermediate deposit. The sur-
face-contour is uneven, swelled into elevations at regular points.

The presence or absence of a beaded deposit between and dis-
tinct from the membranes of scales has formed a branch of my
inquiry, and I endeavoured to satisfy myself upon the point by
tearing open or crushing between glasses such specimens as showed
the phenomenon of beads in a marked manner by ordinary illumi-
nation. The only results I obtained on these occasions were nega-
tive. One of the most marked examples I have endeavoured to
represent. It is from one of the exotic Argynnide, but I am
unable to name the butterfly whence I got it. The scale was torn
in such a manner as to display the interior of the upper and lower
membranes. There was no débris in its neighbourhood resulting
from the escape of any fluid matter or beads, and the damaged
membrane only gave evidence that its folds or corrugations were
destroyed. The colour of the scale was deep yellow. In all other
similar experiments, except where I had actually pulverized the
scales in my efforts, similar negative appearances were presented.

Thus, the investigation led me to the conclusion that whatever
beads (with exceptions to be noticed presently) I saw in the scale,
before submitting it to injury, had no real existence as beads, but
were due to the interference of the rays of light by corrugated
membranes; they were ghost-beads, in fact.

A still more striking example of these ghost-beads or illusive
appearances is given in the iridescent scales of the beautiful West
Indian moth, Urania Leilus, which, like those of the Diamond
beetles, display chromatic effects by transmitted as well as by re-
flected light. When one of the semi-transparent scales is taken
(say one of those orange-red by transmitted, and metallic-green by
reflected light), and the surface next the object-glass accurately
focussed, an appearance like A in the illustration is seen; but if
the focus be altered so as to penetrate into the scale, views resem-
bling B, C, and D are given (Plate LXX.), according to the depth
to which we try to penetrate our glance into the interior of the
scale and the quality of the illumination we use.

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Royal Microscopical Society. 5

This experiment is a very curious one, and has occupied a great
deal of my attention. Sometimes I have succeeded, without any
difficulty, in satisfactorily proving to myself by rapidly calling into
existence, and as rapidly dismissing these almost palpable beads,
that they were mere illusions; and at other times, when I have
wished to do so, I have found it impossible so readily to call them
up, or to make them disappear if already in view. These failures,
I believe, were due to a predisposition in my own mind at the time
to recognize one view more strongly than the other, rather than to
want of skill; though no one knows better than myself that the
necessary adroitness in manipulating high powers is not always at
one’s own command.

Another curious example of breaking up the surface of a scale
into false beads at pleasure was afforded by the inflated plumule of
Pieris Agathina (Plate LXX.). (1 have drawn it under conditions
which seem to me to yield a truthful view.) On raising and lowering
the achromatic condenser, and varying the illumination, some re-
markable effects were presented,—now the longitudinal ribs assumed
a beaded appearance, and directly afterwards the lateral ones resolved
themselves each into three or four similar false images.

A similar experiment was tried with the scale of the English
mosquito, Culex pipiens.

These and many other experiments, especially the examination
ef scales which lie across each other at various angles, causing dis-
tinct and palpable beads where the ribs intersect (an optical effect
familiar to most of us), lead me to hold the opinion very strongly
that very much of the beaded appearance we see on scales (how
much 1 would not venture to say) is illusive, and very often caused
by the “ dodges” we resort to in illuminating them.*

As regards an internal deposit in scales, suggested to be the
case in the article in ‘The Student’ for February on the Scales of
the Lepidoptera, I venture to dissent from that conclusion; and
perhaps I may be permitted to state why, theoretically.

Such a deposit would, I think, considering the purely protec-
tive, and sometimes only ornamental, functions of scales, be of
neither use nor ornament. It would detract from their elasticity
and lightness, while it would add to their weight. Its presence
could only, I think, be atoned for by some great necessity like that
of the bulb and medulla of vertebrate hairs, which is a store of
growing materials, needed by the slow and gradual growth of these
structures. But insect hairs or scales—for no one doubts these are

* A lurking suspicion exists in my mind that some of these “dodges” pro-
duce results approximating to those which Dr. Pigott obtains. For instance, for
the last_six or seven years I have been acquainted with the so-called beads upon
the scales of Deegeria domestica and Macrotoma major ; but I have not hitherto

interpreted them to be other than corrugations, vide ‘Science Gossip’ for 1867,
Figs. 43, 44, and 50, where the scales are figured.

a

6 Transactions of the

closely analogous, if not identical structures (I furnish a few ex-
amples of transitional forms which might be multiplied ad libitwm)*
—are fully developed before they are exposed to external influences
at all,—z. e. from the moment when they become external appen-
dages they do not grow. So that I cannot see the necessity, as a
rule, for any growing matter in their interior. There are some
hairs or spines on the legs of spiders, I know, which form sheaths
for new ones, but I do not refer to these: they are more than mere
hairs. Let anyone, by way of experiment, examine carefully the
hairs of caterpillars, or the more delicate hairs of spiders, and I
think he will find them to be dry membranous hollow tubes, often
of simple structure, and quite as often very complex.

Believing as I do that the Podura beads, which are just now so
eagerly looked for by microscopists, partake very much of the nature
of the illusive appearances I have so far alluded to, I nevertheless
do not decry such appearances. ‘Their cause resides in the scales
and not in our object-glasses ; in fact, I think the better our object-
glasses are, the better they will be shown, provided always that we
illuminate the scales in the manner required to throw up these
beaded shadows. We see them with the same mixture of delight
and incredulity that we applaud the performances of Pepper’s Ghost.

But there are other beaded appearances in scales, the causes of
which we can better understand.

Let us take any Lepidopterous scale, possessing much colour and
opacity. Let us illuminate it with a very strong light, and bring
high enough amplification to bear upon it; and we shall find that
the substance} which causes the opacity and colour of the scale is
granular, and for the most part of regular circular or elliptical out-
line in its minute details. It seems to reside upon, or very near
the surface of the membrane, which it renders more or less opaque,
without, so far as I can discover, increasing its thickness. In de-
scribing the scale of Amathusia Horsefieldit some years ago in the
‘Microscopical Journal, Mr. Warren De La Rue fixed his attention
more particularly upon this one feature of scale-structure, and gave
an account of it which is, to my mind, quite satisfactory. He con-
sidered these granules to be pigment, and spoke of them as such.
Since his paper is largely quoted in Quekett, and a copy of the
original drawing appears there too, I need only indicate where
interested inquirers may read his opinions.

1 think the term “ pigment cells” which he uses, is a suitable
one to describe these almost omnipresent granules. ‘They are of
such general occurrence, and oftentimes of such a pale tint, that I
would not venture to assert any scale to be wholly without them,
though clearly in some scales they are very numerous, and in others

* Seales from Cyphus Germari, and scales from larva of Attagenus.
+ The note by Dr. Maddox appended may afford a clue to its chemical nature.

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Royal Microscopical Society. 7

very few. The beautiful drawings illustrating the paper in ‘The
Student’ for last February, to which allusion has already been
made, strike me as being faithful representations of these pigment
granules. I take exception, however, to those showing beads in the
Podura scales, for these seem to me to represent in an equally
satisfactory manner, the “ ghost-beads” I have spoken of above.

Thus, provided others can confirm my observations, the exist-
ence of two causes of beaded appearances has been traced in extreme
cases ; but how far, in some scales, either of these causes prepon-
derates over the other, will be, I believe, a puzzle to microscopists
for many a day to come.*

But we are not done with the scales of insects. There yet
remains another feature to be briefly alluded to, namely, the modifi-
cations of the folds or corrugations of the membranes themselves.
Tn some scales (see the figure of the scale of the larva of Attagenus)
the corrugations are such that the surface presents longitudinal
grooves and ridges only. In others (and by far the greater number
are of this pattern), a second set of corrugations crosses the primary
set at right angles, breaking up the surface into embossings with
rounded-off edges.}

In order of importance this feature should be spoken of first,
since it is that which gives the primary character to the scale ; but
as due prominence has been given to it in a former paper, it will
not be necessary to dwell at much length upon it here, particularly
as a more extended examination of the scales of insects has tended
to strengthen me in the views I there expressed, rather than to
alter them.t

To illustrate the three features which I have endeavoured to
enumerate, as puzzling us in our examinations of insect-scales under
high powers, I have selected an accidental experiment, which I
thought so curious, as to make a drawing of on the spot. I had
been mounting some slides of the scales of Petrobius maritimus, ,
and noticed in some of the slides that the cement ran in under the
glass cover. Several of the scales confined a bubble of air between

* Tt may be that these pigment granules often exist in the membranes of scales
in an almost colourless condition. I believe they are almost universally present
in the membranes of highly-organized scales, such as those of the Lepidoptera ;
and the only scales where I have been unable to discover them myself are those
of the Thysanura, making exception, however, to the scale of Petrobius, which
presents much similarity to the scales of many Lepidopterous insects, and in which
they exist beyond a doubt. It does not follow, however, that because I have not
been able to convince myself of their presence in Lepidocyrtus, Seira, and Temple-
tonia, that therefore they are absent in those genera.

+ Not always rounded off, however; sometimes they form rectangular divisions
in the scale. (See Dr. Maddox’s note appended to this paper. He deals with this
portion of the subject more thoroughly than I do.)

¢ It will be recollected that, in that paper, I made exception for the existence
of pigment and iridescence, which needed a more complete examination than I

could then make, ere I could comment on Dr. Pigott’s paper, read the same even-
ing as mine, and with the contents of which I was previously quite ignorant.

r

8 Transactions of the

them and the cover for some minutes after they were surrounded
by the cement ; and the appearances which this gave until the air-
bubble became disentangled from the scale, and floated away as a
globe, were carefully watched. One drawing gives the aspect of
the surface of the scale accurately focussed, showing the corruga-
tions very distinctly in the bubble portion, and the granular bodies
are roughly indicated in that portion immersed in the cement, to
which I have referred as “ Pigment.” The other, representing the
result of a little deeper focussing, gave a rather better image of the
aforesaid pigment granules, while the beaded appearances which I
look upon as spurious put im a strong claim to notice in the bubble-
position. Strange to say too, these were in alternate longitudinal
rows of greenish-yellow and blue, a phenomenon, however, with
which my object-glass (Merz ;';) may have to do, since it always .
gives a good deal of colour.

To exemplify what I take to be hemispherical embossings of the
membrane, one of the modifications of corrugations which is exceed-
ingly common, I bring forward the scale of the mland Petrobius
found by Dr. Gray at Dolgelly this summer. The scale is much
like the finer scales from its marine relative, but perhaps shows the
embossings a little better than these do generally. I do not think
the insect has been found before, and its scale is certainly new
to microscopists.*

This variety of corrugation, which may be likened to embossing,
is the nearest approach that I can find to real beads in scales, and
as it is exceedingly common it can be easily exammed. The dots
are wonderfully distinct on the dark scales of Urania Letlus} and
Euploca Midamus and many others, and if the slide is mounted so
that a drop of water can be introduced under the cover while the
scale is in view, much assistance is rendered to the investigator.

I would here take the opportunity to allude to the glimpses of
the mode of development or plan of structure which is displayed in
immature scales. ‘The suggestion was made to me some time ago
by Mr. Lowne, but the difficulty of its investigation almost put a
stop to further researches on my part, though its force was appa-
rent to me at once. Where then shall we look for materials to
study? I think we have on any slide of Podura scales the very
materials to hand. Everybody knows that slides of Podura scales
contain vast numbers that are too small and too difficult of resolu-
tion to examine with satisfaction, and so we all move these out of
the field in order to bring the largest only under view, and we look
at these time after time, and express our puzzled opinions as to the
structure in terms which need only to be compared with each other
to show there is a great want of harmony in them.

* The scales of Macrotoma (Poduride) are also excellent examples.
+ See Figure on Plate LXIX.

Royal Microscopical Society. 9

I believe the Thysanura give the most remarkable examples,
perhaps the only ones, where the change of skin takes place at a
time when the scales are in all stages of development. From that
moment, I believe, the growth of the scales is arrested; they dry
up, and, by forming a somewhat thick layer of elastic corrugated
plates over the delicate skin of their owner, provide a protective
covering admirably adapted to the wants of the fragile creature
they adorn. ‘Their slender attachment to the skin is an additional
evidence of Creative design; for were they to remain attached in
spite of all the concussions the Podure are subject to in their active
leaps, the tiny creatures must suffer endless contusions.

Now the smallest scales, as I see them, appear to be mere filmy
sacs; those a little larger give some evidence that the membranes
collapsed in drying, but they are so delicate that the wrinklings
which such a process would give rise to are very indistinct.* Larger
scales display the feature more and more strongly, and in the largest
of all we see those wrinklings have acquired importance enough to
occupy the patient attention and study of hundreds of clever ob-
servers. So much for the Poduride.

In the Lepismide (Lepisma and Petrobius) we get yet more
information. The organization of these insects being of a higher
type, it is reasonable to expect to find a higher and more compli-
cated development in their scales; and this I think we do find.
As I see them, and in my former paper I have dwelt on this point
in detail, they form the link between the lower forms of scales and
those possessed by the Lepidoptera, Diptera, &c.

The unintended length of this communication precludes my
touching upon Iridescence, a subject which may at some future
time be attempted, at least so far as bringing forward some curious
effects m iridescent scales. I will therefore sum up the principal
notions that the above experiments have led me to form, previous to
making a few comments on Dr. Pigott’s paper.

1. That the principal structural feature in insect scales is cor-
rugated membranes—a plan ensuring the maximum amount of
strength and elasticity with the minimum of weight.

2. That there are a few scales having one surface hackled.

3. That the ornamental requirements of scales are fulfilled
either by iridescence or the possession of pigment granules in or
upon the membranes.

4. That the beaded appearances seen in scales are due to the
following causes, either singly or collectively :—

a. Corrugations, taking the form of hemispherical embossings.

b. Pigments.

ce. Shadows of projections, or folds in the membranes, either

within or beyond the focus of the object-glass.
* Of course there is a predisposition for wrinklings of a definite pattern.

+

10 Transactions of the

Though I do not feel satisfied that Dr. Pigott is correct in
speaking of the basic membrane of a Podura scale, above and below
which he says beads lie in chains, I yet think what he sees has
some foundation; and it is our business, in the absence of experi-
ence with his aplanatic searcher, to ascertain if what he shows us
bears any analogy to, or is conflicting with, ascertained structure in
other scales. If the latter, no amount of optical knowledge on his
part would convince me he is right; and, on the other hand, if
analogous appearances have been seen in similar structures before,
I shall be prepared to accept his views, subject to correction.

Now, it is clear to my mind that Dr. Pigott’s discovery as
regards the scale of Lepidocyrtus cwrvicollis admits of one or other
of two interpretations :—either the appearances he sees are caused
by pigment granules in the membranes, identical with those seen in
the scales of insects generally, but which have never yet been as-
serted, so far as I know, to exist in Podura scales, or he sees “ ghost-
beads,” which are always the result of some surface inequality, such
as minute corrugations of the membrane or membranes, the exist-
ence of which minute corrugations in the scale of Curvicollis has
likewise never yet been suspected. And, whichever interpretation
be finally accepted, I for one admit that a step is gained, and Dr.
Pigott can claim the credit of being the first to notice it.

This result places me in a position to view with favour the
method by which he has obtained the appearance. Another consi-
deration is, that it is highly improbable that the lens Dr. Pigott
has used in the investigation is the only exponent of the truth,
such as itis. (I think he admitted something to this effect at the
October meeting.) Can I then test the value of this method of
examination by means of the apparatus I have by me?

I have endeavoured to obtaim upon L. cwrvicollis the same re-
sults as he does, and on two occasions was approximately successful.
My process was as follows. The lamp was on my left, and about
ten inches from the microscope which had the achromatic condenser
(Powell and Lealand) on, and the smallest aperture of the diaphragm
accurately centered. The mirror was adjusted a little to the right
of the axis of the microscope, so that only enough light to illuminate
without flare passed up through the lenses, and the illuminating
beam consisted of rays rendered parallel. It seemed to be indis-
pensable that the few large scales (for it was only a few in which I
thought I saw it) should lie in exactly a horizontal direction, with
the shafts pointing to the left of the field of view. The scale of
Degeeria domestica (or Seira domestica, for Sir J. Lubbock has
recently given the insect a new name) showed the same, or very
nearly the same, still more strongly. I went through the whole of
the Podura and Lepisma scales and saw beads abundant every-
where. Although I had seen the most of these beads before, it was

Royal Microscopical Society. 11

plain to me that by accident I was getting results closely resem-
bling Dr. Pigott’s—and this too without the adventitious aid of an
aplanatic searcher. I tried to obtain a witness in the person of a
lady, as Dr. Pigott did; but, I am sorry to say, that until I told
her to look for “ beads,” her testimony was not valuable, except as
showing either how strong a part the imagination plays in spite of
ourselves, or else that I needed an aplanatic searcher to make all clear.

As regards this tour de force, I have by dint of a good deal of
inquiry and observation obtained a notion which is more or less
correct. My notion is that it simply consists of a species of object-
glass* of 1 inch or 14-inch focus (or thereabouts) placed between
the eye-piece and observing objective. It is capable (within certain
limits)} of being shifted to any distance which practice shows to
give the best results. The larger of the two lenses forming the
aplanatic searcher is directed towards the observing objective and
the smaller towards the eye-piece. Thus explained, some observers
may recognize it as a plan which has already been put in practice
for amplifying the power in their own microscopes, but discarded as
unsatisfactory. Moreover, I have, by the kindness of Mr. Curteis,
been favoured with the loan of one of these instruments constructed
by him on Dr. Pigott’s principles. The “searcher” was a 14-inch
objective originally constructed for photographic purposes by Dall-
meyer.

The results were much better in my hands than I anticipated,
and, so long as comparisons (which the proverb says “ are odious”)
were not made, they might be called good: but directly this test of
their goodness was tried, the verdict went against the “searcher.”
While there was great gain in amplification there was a palpable
loss in definition : less certainly than I was prepared to expect, but
still a palpable Joss. The objectives used in this examination were,

% Smith and Beck,
Powell and Lealand,
Andrew Ross,
z Powell and Lealand (dry),
='; Merz (immersion),

TA cc

and each and all of them performed better without than with it, so
far as giving a brilliant and well-defined image. The objects chosen
were Plewrosigma Kormosum (dry), and the whole series of Thysa-
nura scales. Mr. Fitzgerald assisted me in the examination, and I
believe came to the same conclusion as myself.

On a second occasion I used an ordinary 14-inch objective by
Ross as a“ searcher,” t and obtained such good results that I was
nearly altering my judgment upon it. But, remembering that I

* Does it differ from an ordinary object-glass more than object-glasses of the
same focus by different makers differ from each other ?

¢ The contrivance by which this is effected is ingenious.
} Subsequently I tried a 2-inch by Smith and Beck with good results.

12 Transactions of the

could fit up my second microscope with equal power, exactly simi-
lar illumination and duplicate objects, and place both microscopes
so that I could look first into one, and then into the other, without
setting off my chair, I determined to put the plan in practice; and
accordingly did so. As before, comparisons were odious. The
image was much clearer and better defined in the microscope where
the amplification was obtained in the objective only, than in the
other. I think on this latter occasion the definition was at least as
good as the best I ever saw under Dr. Pigott’s own microscope ;
and certainly it was greatly superior to that given in his instrument
at the meeting of the Royal Microscopical Society in October last.
(I mention this to show my conviction that there is no material
difference between the searcher he uses, and the one * lent to me.)

The objects which he has hitherto exhibited are not by any
means crucial tests. They are P. Formosum (dry), scale of Degeeria
domestica, and scale of Macrotoma (named on Dr. Pigott’s slide
Podura plumbeat). I have always been under the impression that
I had seen them better without any searcher at all, in the micro-
scopes of Dr. Gray, Mr. Fitz Gerald, and Mr. Delferrier, and also
in my own; and there is evidence in the celebrated American pho-
tographs of the Test-Podura scale (Lepidocyrtus) that the so-called
beads have not been wholly obscured from view.

I know that the lens I have used is not the exact combination
which Dr. Pigott has had made, but I get precisely the same abun-
dance of beads as he describes; and the same abundant display of
brilliant blue and yellow, green and ruby effects which he dilates
upon are associated with all its best performances. Moreover, there
is the same subtilty of adjustment of which he speaks—a difficulty
which Dr. Maddox (I believe) finds nearly unsurmountable: a point
upon which I also can speak feelingly, since I damaged my “ fifth”
objective (by Smith and Beck) in the endeavour to obtain it accu-
rately. Then there is the occasional excellent definition to counter-
balance the unbelief which so lavish a display of colour in objects,
usually transparent, infuses into one’s mind.}

* T retain the term “‘aplanatic searcher” in speaking of this contrivance, for
the obvious reason that Dr. Pigott has used it, and until Dr. Pigott corrects me I
must still believe that it is properly so called.

+ The genus Podura is non-scale-bearing, and is represented by the active black
insect which skips over the surface of the Hampstead Ponds, looking at a distance
like a quantity of soot on the surface of the water.

+t Dr. Maddox writes to me that he did not get on well with the aplanatic
searcher which Dr. Pigott was good enough to lend him. He says its value
seemed to be chiefly in the facility with which many structures gave complemen-
tary tints very defined, thus facilitating the study of tissues of different thickness.
But he further says the results were better than those obtained by amplification
with an ordinary objective of low power at the end of the draw-tube,—a plan he
has tried in company with the late R. Beck ; and does not seem to value results
of this kind, unless daylight and artificial illumination tell the same tale. He
also makes some valuable observations upon chromatic phenomena, which I have

asked him to put in a convenient form, as they are likely, as mere extracts, to
lose much of their force.

Royal Microscopical Socrety. 13

Finally, in spite of the disadvantages and difficulties which seem
so far to attend this mode of examination of objects—difficulties
and disadvantages that in the light of more knowledge and more
experience may be dissipated, I do occasionally get glimpses which
surprise me. I will not venture to pronounce an opinion upon
them, but merely lay the whole matter before you as a subject
worthy of careful exploration, and certain to yield most interesting
results. I notice that, whatever other adjustments are necessary as
regards the correcting collar of the observing objective or the apla-
natic searcher itself, it seems to be imperative that a distance of not
less than seven inches shall be kept between the eye-piece and the
searcher, at risk of cutting the margin of the field of view.

. It was my intention to have exhibited an experiment with it,
but the accident to my }-inch objective has warned me not to
attempt it under circumstances so unfavourable to perfect success
as the present occasion, but I hope to do so ere long. I append an
extract from one of Dr. Maddox’s letters to me on the structure of
scales, and I look forward to further observations by him in eluci-
dation of many difficult portions of the subject, especially the chro-
matic effects :—

Extract of Letter from Dr. Maddox.

“My object was to try amongst the readily procurable and
ordinary scales the effect of various chemical and destructive agents,
and I fancy by these means we may make out much of their struc-
ture aided by the microscope, though with it alone I fear we shall
be constantly verging on the dubious. Whatever the surfaces, there
appears a framework amongst them which is connected to the inner
surfaces, and the nearer the form of it corresponds to small squares,
the nearer the approach to beading, and the coarser at the corners
or junctions the more resemblance to spherical embossings.

“These spaces seem to be filled with a greasy matter partly
soluble by boiling in liq. amm. fort., then treating with chloro-
form at a boiling point—performing these operations on the slides,
and allowing the soluble matter to be washed away by the solvent
last used. ‘Then staining the scale with anzline or other suitable
material and mounting in a dry state, also in a dense liquid satu-
rated solution of acetate potasse, &c.—or boiling in liq. potasse,
washing with distilled water, then with ether and chloroform—and
drying by heat—in fact varying these agents; also using turpentine
to boil these scales in, and then permitting some thin coloured resin
in solution in turpentine to flow over them and dry by heat. Nu-
merous methods were tried and under high powers, advantageously
as regards structure.”

14 ~ Transactions of the

III.—On an Optical Illusion Slide: Cracks in Siliea Films.
By Henry J. Suacg, F.G.S., Sec. R.M.S.

(Read before the Royat MicroscopicaL Society, Nov. 9, 1870.)

Aurnoucs there may be much reason in the complaint of micro-
scopists that existing objectives leave them without the means of
distinguishing many characteristics of minute structure, such as
ultimate organic tissues, cell. walls, &c., it is certain that the pro-
gress of knowledge is more often impeded by difficulties of inter-
preting what the best instruments can show. The long-continued
controversy whether the markings of diatoms consisted in elevations
or depressions, the discussions concerning the scales of Lepidoptera
and Thysanura, together with many others that will occur to the
practical student, are illustrations of this fact, and we can only
expect to arrive at greater success in discriminating between appear-
ances optically true under certain conditions, and veritable facts of
form and texture, by becoming familiar with the circumstances
under which illusions arise. As a small contribution to this end,
the attention of microscopists is called to “An Optical Illusion
Slide,” which may be thus prepared. Place a drop of an aqueous
solution of colloid silica, obtained by dialysis,* on a glass slide, and
evaporate it, elther quickly over a lamp, or slowly in a place free
from dust. By this means a film of transparent silica is deposited
upon the glass, fissured in curious and complicated patterns by
numerous cracks. ‘These cracks when highly magnified present a
variety of forms, something like a veined leaf, or the patterns on a
complicated city map, with long lines of straight and curved streets,
Squares, ovals, circuses, &c., and in certain places all sorts of
angular and rounded outlines. In general the cracks take place
without materially altering the level of the surface, but occasionally
an edge will be found turned up.

If a slide thus prepared be examined in diffused daylight, its
real character is not difficult to discern, especially if attention is paid
to the widest of the fissures and the largest of the isolated silica
plates. By lamp-light, however, all the finer cracks, viewed as
transparent objects with a power of from 200 or 300 and upwards,
look like elevations, and that focussing which exhibits them in the
strongest relief would be supposed to be the most correct, from the
superior distinctness of its outlines.

By the employment of a central stop of an achromatic condenser,
the illusion becomes more striking. If a large angle of aperture is
used and the field flooded with light, prismatic colours appear abun-
dantly, one edge of the crack bemg blue and the opposite one red,

* Silicate of soda or potash is dissolved in distilled water, enough hydrochloric
acid carefully added to separate the alkali from the silica. The liquid is then
placed in a dialysing drum, and the crystalline salt escapes, leaving the silica dis-
solved in the water that remains.

Royal Microscopical Society. 15

aud in many places rows of narrow coloured bands like Newton’s
rings will be noticed, especially if the power is high enough—say
600 to 800 and upwards. Unilateral light does not clear up the
question, an eye being still best satisfied with the focussing that brings
the lines of pseudo-elevation into the greatest sharpness and relief.

With dark-ground illumination a very beautiful effect is pro-
duced ; the edges of the cracked silica film being brilliantly lumi-
nous, while the uncracked portion of the film, and the interspaces
between the luminous edges of the cracks are dark. The larger
portions of the fractured silica, and those most detached, show the
true nature of the object with this illumination; but the same can
scarcely be said of the finer cracks, which might easily be taken for
small tubular vessels anastomosing in all directions.

In these experiments, the eye is most readily deceived by a high
power. For example, let the slide be viewed with a 43-inch and an
A eye-piece, with transparent illumination ; the true nature of many
cracks will be seen; then substitute a C or D eye-piece, and the eye
becomes most doubtful of that focussing which is nearest the truth ;
the aspect of bright clear ridges being most satisfying and agreeable.
The reason of this is evident. When the surfaces of the silica films
are focussed, there is nothing particular to see, as they are smooth,
clean, and exceedingly transparent, while the cracks look dingy and
imperfectly defined. A little lower focussing does not seem wrong,
because there is nothing on the silica surface to become indistinct,
while the cracks appear in fine relief, rounded and often slightly
tinged with colour from refractions, or reflexions, or both combined.

$-inch or 35-inch Lieberkuhn reveals slight inequalities in
the surface of the split films, and when they are illuminated with
Messrs. Powell and Lealand’s modification of Professor Smith’s illu-
minator for opaque objects with high powers, many fragments of the
film exhibit prismatic bands, and some show complete series of New-
ton’s rings. It is necessary to use the smallest of the diaphragm
stops with this apparatus, or the field will be flooded with misty light.
The larger fragments give the best colours, which seem to arise from
the tension of the silica in drying, leaving minute air-spaces of vary-
ing thicknesses between the glass side and the films. The coloured
bands vary in shape from approximate circles and ovals to other
curves of various characters. The circular form is best shown where
the film has solidified round a central boss.

Portions of the films sometimes appear of the same dark-grey
tint of the ground, while others are luminous. This appears to
result from the obscure parts being in such complete contact with
the glass, and with upper surfaces so completely parallel to the glass
surface as to produce the same effect upon the light which the glass
surface does.

NOT Vie (t

+

16 Object-glasses and their Definition.

IV.—Object-glasses and their Definition.
By F. H. Wenuam, Vice-President R.MS.

Ovr thanks are due to Dr. Pigott for his laudable attempts to
advance the microscope object-glass, but as he appears to stand
forward as the pioneer of a new era in their construction, ignoring
all glasses made before the publication of his first essay as “old-
fashioned,” such dictatorship naturally challenges inquiry as to the
merits of his investigations, and whether they have in any way con-
tributed to the end in view.

His papers published in the July and September Nos. of the
‘Monthly Microscopical Journal’ for 1870, only tend to mystify
the simple action of the immersion lens, for he therein endeavours
to show that there are some new and hitherto unnoticed optical
conditions peculiar to the immersion front, and brings forward the
remarkable error that, if various fluid media, such as water, tur-
pentine, &c., are introduced between the cover and front lens, a
larger aperture or greater angular pencil of rays is transmitted from
a radiant point or object, when mounted in balsam, but in fact the
angle must necessarily be limited on such objects.

In the year 1854 Professor Robinson and myself * demonstrated
simultaneously that the angle of illumination, and also the aperture
of the object-glass, were reduced on objects mounted in Canada
balsam : Professor Robinson assigned the limit as 81°, I stated it at
82°. This slight difference refers to the refractive index of the
glass cover, which was not taken as the same in each case. ‘The
pencil must of necessity be confined within the angle of total re-
flexion; this may vary from 40° to 41° 30”, according to the
density of the crown-glass cover. ‘This so far is an established
optical fact. Dr. Pigott’s inference is, that by the introduction of
fluid films of various refraction, between the front lens and cover,
more or less of the entire aperture is again recovered and utilized,
as the total reflexion of the upper surface of the cover is then pre-
vented, or is extended definitely according to the refractive index of
the interposed medium employed, and that a greater angle is trans-
mitted in consequence. ‘This assumption is taken quite regardless
of the dimensions and construction of the component lenses of an
objective, and their capability of admitting rays in excess of a cer-
tain angle. The paper is prefaced by the following remark,—“ One
might almost venture to declare that perhaps too much exclusive
attention has been paid to the objectives, to the neglect of the pen-
cils radiating from the object . . . the primary behaviour of the
tiny spray of rays is of the last importance to the final definition.”

* “Quarterly Journal of Microscopical Science,’ July, 1854, p. 212; ibid., Jan.,
1855, p. 165.

Object-glasses and their Definition. 17

This is ominous of the series of errors which the author afterwards
brings forward. Anyone that has worked practically at the subject
will admit that the focal point of an object-glass of large aperture
is confined within such a very minute limit as to distance, that it is
impossible to assume its position for the purpose of tracing the course
of a ray through the entire combination. In fact, the work must be
commenced from the posterior or conjugate focus, which, though a
variable distance according to the power of the eye-piece or its
position, is in some cases so far back that rays only slightly con-
vergent or nearly parallel may be commenced with, and the result
will approach near to accuracy in the focus, or final convergence
beyond the front.

The same optical law that limits the aperture of any object-glass
to near 82° in a balsam-mounted object also determines the angle
in the lens at which the rays diverge after being refracted from the
plane surface of the front. This can never exceed 82° in a dry
objective ; nor can it be greater on the immersion system, where an
interchange of front adapts it to both conditions, as the very correc-
tion which necessitates the form of the back lenses and their dia-
meters will not transmit a greater pencil; and therefore if the front
is immersed in balsam for the purpose of viewing an object placed
therein, this angle of 82° or less, as the case may be, instead of
converging at 170° as from the dry lens, is continued right to the
object, supposing the refractive index of the front and balsam to be
the same, which they are nearly.

In Dr. Pigott’s diagrams, p. 134, Plate LX., of the September
No. of this Journal, Fig. 2 is a form of achromatic that is now never
employed as a front. The focal pomt in each example is taken in
quite an impossible position, for the rays there shown arrive at the
convex back of the lens nearly as a radius, or from its centre of
curvature, so that at this surface there would be scarcely any refrac-
tion, the rays passing through nearly straight, most of them never
reaching the succeeding lens at all, and those that finally emerge,
instead of forming a conjugate focus behind, would be divergent ; and
yet after quoting my objections he still complacently refers to his
Plate LX. as the standard for illustrating “the aberrations of the
two systems.” *

The annexed diagram, Fig. 1, 284 + times the size of the ori-
ginal, shows the marginal rays of mean refraction projected in the
exact position that they occupy through the 4th described in my
paper “On the Construction of Object-glasses.”t The focal point
’ from the front lens is -0126, or near {>th of an inch, the extreme

* See p. 254, Nov., 1870.
+ The original diagram was much larger, but was required to be reduced to
bring it within compass for these pages. nee
} ‘Microscopical Journal,’ Feb, 1869, p. 112. 9
Cc

+

18 Object-glasses and their Definition,

aperture is 130°, and the rays will not enter beyond this limit,
therefore the ray after refraction by the flat front must occupy a
fixed position which cannot be exceeded, and so on during the whole
course of the ray through the entire combination, till it converges to
the long conjugate focus at the back. These lines being unalterable,
it must be evident to the merest tyro in optical science that if the
front lens is immersed in Canada balsam, but little or no refraction
can take place at the flat surface, and the rays from this, instead of
meeting at 130°, will proceed straight on, as shown by the dotted
lines, at an angle of about 74°, showing the loss of aperture in
balsam. Iam here assuming for the sake of simplicity that there
is no thin glass cover intervening in the mass of balsam between the
object and lens, as its presence would not materially influence the
result. .

I may, now that the diagram is under consideration, make a few
remarks concerning this th, as its performance is known to many.
Comparisons were often made, and it held its own for some years,
This is not adduced for the sake of exalting it as a model of per-
fection, but for the discussion of possible defects, and the direction
in which improvements might be anticipated. Commencing with
the front lens. The simplicity of this, and also the determination
of the radius by the intended power of the lens, leaves but little scope
for alteration. ‘The correction for thickness is obtained by trial, as
I haye explained in my paper. The diameter is limited by the pro-
posed aperture. For 130° rather more than this segment of the
circle must be allowed. For 170° we approach near to a hemi-
sphere. We now come to the middle; it will not do to make this
of too long a focus, or we cannot command our aperture, therefore
the curves are deep and the lens thick. A short radius in the back
emergent surface is not material, for the bending of the rays is here
gradual ; but in all achromatics it is important to get the contact
surfaces of as long a radius as possible, hence the value of the triple
back. Now in the middle here delineated these surfaces are deep,
so far, that were it not for the Canada-balsam film that cements
them together, which allows the transmission of the outer rays,
these would be lost from total reflexion from the concave surface of
the flint, as shown by the dotted line. As such abrupt courses are
prejudicial both for the correction of chromatic and spherical aber-
ration, the question is, how can this be remedied? Ist, by making
the lower surface of the concave deeper. This can only be done to
a limited extent, or we have an excess of outward coma that is after-
wards difficult to cure; indeed if the quality of the glass were suit-
able I would prefer to make this surface flat. Another way would be
to make the middle a triple. Andrew Ross employed this, but aban-
doned it eventually, probably on account of its complexity. If the
first and most abrupt bending of the rays were sustained by two

Fic.) tl.

20 Object-glasses and their Definition.

single lenses in front, they would emerge more nearly parallel, and
pass through the middle at a more favourable angle, which could
therefore be made with a longer focus and radius. But the best
remedy would be an improved quality of glass. The flint with a
less refractive and higher dispersive power, and the crown vice versa,
I believe it possible that such a glass could be made. Of the triple
back little need be said, as the bending of the rays is here easy:
before this was introduced the old form had the defects to which I
now call attention in the present middle, and the marginal rays were
imperfect. and limited the aperture.

Speaking of recent improvements, Dr. Pigott alludes to an
object-glass made on the Lister principle as being “old-fashioned,”
from which I infer that he considers them quite obsolete; but as
long as the adjustment between the lenses exists for the purpose of
obtaining a correct aplanatic focus, so must all object-glasses remain
on the Lister principle, and it is the absolute correction of this focus
for chromatic and spherical errors upon which their perfection must
depend.*

A great advance has been recently effected in the highest powers,
which are now made with a single front; this after remaining for
years unnoticed has triumphed at last. This formula also affords
peculiar facilities for the addition of an immersion front, as I shall
presently show, and to which its success is mainly due.

I will now make a few remarks concerning the Podura. In
the November number of the Journal, Dr. Pigott has quoted and
italicized some sentences from my communications, and placed them
so as to make it appear that I contradict myself, and have been un-
decided in the structure. These sentences, as my papers will show,
referred to the difficulty of proving the spines to be projections by

* IT may here offer a passing tribute to the memory of the late Joseph Jack-
son Lister, to whose researches the present advance of the microscope object-glass
is entirely due, for in the perfection of aplanatic foci, caused by difference of cor-
rection, and corresponding distance between the lenses, he enunciated a fact as
definite as Newton’s law of gravity. Some inclination has been shown to question
this; but it must be remembered that in order to carry out his ideas, he had to
avail himself of the skilled workmanship of the then three rival makers, who,
doubtless individually, effected many improvements in detail in the particular
power that they engaged to construct, and each justly considered that he had
some right to a monopoly in the special objective that his workmanship had made
perfect. This rendered Mr. Lister’s position rather a delicate one, and his remark-
ably amiable and kindly disposition forbade him from coming forward to the injury
of others, and his retiring manner shrunk from anything approaching to public
display ; hence he has been unjustly suspected of reserve. I visited him at his
residence at Upton on two occasions, and on each spent several interesting hours
in going through all his plans and experiments, which were brought forward in
the most candid and confiding manner. Every proposed construction had been
worked out, with all the rays accurately traced through, in large and neatly-con-
structed diagrams, before they were carried out practically ; and I should be glad
to see these very comprehensive plans in the archives of the Royal Microscopical
Society, as I know for a fact that ;+,ths, 1ths, and 1ths, were made therefrom, with
no other alteration than a slight variation in the quality of the glass required.

Olyect-glasses and their Definition. 21

some other means than mere sight, and obtainmg more mechanical
evidence of their form. I said that in a doubled-up scale “the
markings ply round the sharp bend so closely that the keenest ‘eye
cannot detect any appreciable rib or projection ;” but this assertion
I must withdraw, as Mr. Beck informs me that in the coarse speci-
mens, of which he has a variety, the mbs can be seen plainly
projecting at the bend; and his recent communication to the Royal
Microscopical Society concerning the moisture experiment, furnishes
another proof that the markings are longitudinal ribs projecting
mostly on one side of the scale, and are not caused by similar rows
of beads crossing obliquely on opposite sides as Dr. Pigott states.
Whether these “beads” in the form stated are fallacious or not
must be left for the present; there is probably some analogy
between them and those on the ribs of butterfly scales; but if an
object-glass fails to discover any indications of them, the fault may
be in the scale—some of which will show nothing of the kind, for
there is a singular difficulty in obtaming boldly-marked scales in
some localities. Dr. Pigott says that in my last communication I
have “sketched the Podura markings something like an Lrishman’s
shillalah.” Not being familiar with the look of that atrocious
weapon, I do not feel the force of the simile; but I have a very
beautiful and exquisitely distinct: photograph of the Podura, kindly
sent to me by Colonel Dr. Woodward, one edge of which has rounded
away from the cover to which it adheres, bringing the markings
gradually into profile in the form of my sketch. But Dr. Pigott
repudiates photography, saying that it fails to. reveal what the eye
alone can detect, and that the photographer has never yet displayed
the Amphipleura pellucida—simply, I presume, because it has
never yet been tried. When markings have been very difficult to
show by ordinary illumination, I have frequently been surprised at
the wonderful facility with which they are displayed in a solar
image; in fact, Dr. Woodward’s photographs of Nobert’s 19th band
magnified 2800 diameters (a series of which he has also sent to me)
tend to prove this after the long discussion as to whether they have
been seen or not.

I must protest against the positive manner in which Dr. Pigott
still totally condemns the mercury globule as a test for the con-
struction of object-glasses. This self-confidence may be attributed
to non-practical acquaintance with the use of it. That it is em-
ployed solely for the purpose of obtaining a distinct image is quite
a mistake. The greatest value of its indications are when it is
considerably within or without the focus. Commencing with the
back triple, this is first corrected alone on the globule, and the coma
observed both within and without the approximate focus, gives the
indication whether the lenses are right, or what alterations will be
needed to make them on. No optician thinks of the possibility of a

re

22 Olyject-glasses and their Definition.

distinct image with the excessive aberrations both chromatic and
spherical purposely introduced in the back combinations, to be
afterwards neutralized or corrected by the counter-aberrations of
the front. In this way the globule is used throughout the series ;
IT know of no substitute ; and so reliable and comprehensible are its
indications to the worker of lenses, that I have no hesitation in re-
peating this, my former assertion, commented upon by Dr. Pigott,
“that without this test it would be impossible to construct perfect
objectives.” That the separation of points of light on the globule
coming from two sources placed at a given interval is a test, no one
will question. A bad glass will blur them together, and a good one
will separate them more or less distinctly. Andrew Ross employed
this method of separating known intervals, in his experiments on
the defining power due to aperture. Dr. Goring used the reflected
image of the bars of a window, as explained in “ Micrographia ;”
and the globule-reflected image of a Venetian blind, adjusted so as
to regulate the width of the dark and light intervals, also makes an
excellent test ; or the wire gauze and perforated zinc employed by
Mr. Lister.

As again quoted by Dr. Pigott, I have stated in reference to
the immersion lens that “ not either the water or glass cover has
introduced a single new element of correction,’ meaning that these
are combined identically as part of the front lens. This assertion
may have appeared dogmatical, but was based upon practice. My
experiments in the.construction of object-glasses have been conducted
more with the view of originating new combinations than repeating
the same thing. The single fronts were made very thin to begin
with, and the measure for the necessary thickness for correction was
arrived at by means of different thicknesses of glass stuck on the
front with Canada balsam, but more frequently by water ; the dimen-
sion thus obtained was employed for finally making another front of
the correct thickness. The object-glasses were strictly immersion
lenses at this stage of their existence. I did not then think it worth
while to retain a special immersion object-glass (¢. e. one with a thinner
Jront), particularly as several of the covers of my test object. were
cracked and could not therefore be used with water; but as some
further proof of the particulars and dimensions are now needed, I
have recently removed the front of a ;,th and substituted a thinner
one of the same curvature to be used as an immersion. Fig. 2 is
the dry lens fifty times the size of the original; the rays are taken
through from beyond the glass cover, with the object-glass corrected.
for this thickness, which combines as part of the lens. Fig. 3 is
the immersion front, wherein the lens, water, and cover form the
unity, also corrected on the object for thickness. The aperture or
angular pencil passing through the combination from a dry-mounted
test is the same in both cases. In Fig. 2 the thickness of the lens

24 On the Mounting of the Diatom-prism.

in fractions of an inch is *044, radius ‘0315, diameter 062, glass
cover *007, distance of focus from front *004, as shown at a point
in the glass by the dotted lines. The thickness of the cover and
lens together is ‘051. In Fig. 3 the radius and diameter is the
same as the dry lens—Thickness of lens -034, ditto of water film
*012, ditto glass cover *007, total combined thickness -053; so
that the corrected thickness of the water front exceeds that of the
dry lens and cover by 002, or 5$th part of an inch. This differ-
ence may be accounted for by the less refractive power of the
water.

The effect of this immersion lens is to give greater clearness and
brilliancy to the object, and render markings more distinct that were
before scarcely visible with the dry lens. This is in fact attributable
to the saving of light and comparative absence of refraction and
reflexion from the top surface of cover and front of lens. But the
great merit consists in the perfect correction that the adjustable
thickness of the water stratum affords in compensating for every
thickness of cover. Nor is the thickness of an immersion front a
matter of particular nicety, for it can be made as thin as desirable ;
the water will occupy the place of the deficiency.

In the three diagrams I have accurately transferred all the
dimensions, and it can at once be seen how a thickness of front en-
sures both correction and large angular aperture, by spreading out
the cone of rays in its passage through the lens, after the first
refraction, so that the marginal ones fall on the edge of the convex
back, and then emerge in a direction suitable for entering the middle
and posterior combinations, conveying the full angular pencil
through the series.

I have not yet ascertained whether the “aplanatic searcher ” has
any influence in improving definition, as no description of its con-
struction has yet appeared, and it exists more in name than in use.

V.—On the Mounting of the Diatom-prism.
By F. W. Grirrin, Ph.D.

Tue unilateral system of illuminating transparent objects, intro-
duced by the Rey. J. B. Reade, F.R.S., bids fair to be more and more
generally employed as its important advantages become more widely
known. But there are practical difficulties in fitting the diatom-
prism to any large and complete stand, since to obtain the most
oblique beam it has to be brought almost close under the slide,
while elaborate traversing and rotating movements require a thick-
ness of stage which keeps it too far off for its full effect. In the
Ross model this thickness is certainly reduced to a minimum in the

» eee
= --» == eee ee a

On Pierodina valvata. 95

centre, and this suffices for all appliances illuminated from below.
But the necessary depth of the outer ring prevents the side beam
from falling on the prism, or the fingers from reaching its milled
head, when it is brought sufficiently close up. As it is scarcely
worth while to sacrifice the strength and durability of the stand to
suit a single accessory, it is best to bring the diatom-prism above
the stage. It is then completely unobstructed in its movements and
illumination, and works much the same with transparent objects as
Crouch’s admirable parabolic reflector does with opaque ones. The
fitting required consists of a stage-plate sliding in the same dove-
tails as the ordinary object-carrier (which has then to be removed),
and carrying on four uprights, about two inches high, a thin plate
cut out in the middle with spring-clips to hold the object-slide.
This is of course carried, equally with the main stage, by all the
traversing and rotating movements. The diatom-prism, mounted
as usual, fits into the end of a tube carried by the sub-stage, and
long enough to project through the aperture of the principal stage.
The prism can thus, when desired, be racked-up close under the
object with every facility for adjusting and lighting. The bottom
plate is cut out on its lower side, so as to slide over this tube after
fixing the prism in the upper end.

I may note for those who desire a cheaper and simpler, yet ser-
viceable, arrangement, that the diatom-prism works very well with
the excellent glass-stages of Messrs. Beck and Crouch, since these
are thinner than stages traversing and rotating mechanically can
well be made. As the rotation of these is satisfactory, and the
sliding movement sufliciently smooth and delicate for use with }th
inch, they are adequate for ordinary prism-work.

VI.—On Pterodina valvata: a New Species.

By C. T. Hupson, LL.D.
Puate LXXII.

Preropina is rarely met with in the neighbourhood of Bristol ;
and I had not taken more than six specimens, and these all of
P. patina, during the last sixteen years. Nothing can be more
tantalizing than capturing a solitary Pterodina. It is so deli-
cately transparent, that it is extremely difficult (indeed, I found
it almost impracticable) to see it with the naked eye well enough to
- catch it with a pipette, in order to place it on the compressorium
ina drop of water, whose diameter should not greatly exceed the
creature's length ; and yet with solitary specimens. this is the only
method by which a satisfactory investigation of its structure can be
secured. Even when this is accomplished, Pterodina is of such

26 On Pterodina valvata.

evanescent thinness that I was unable to hold it between two plates
of thin glass without driving the drop of water away from the
rotifer. I made use of each of Ross’ later compressoriums, and
it is the first time that they have ever failed me; their admirable
construction has hitherto enabled me to hold gently the minuter
rotifers in the smallest possible quantity of water. The advantage
of being able to bring two plates of glass together, within the
distance of a rotifer’s thickness, with a truly parallel motion, is this ;
that the drop of water in which the rotifer is placed may be made
as small as the rotifer itself will bear without fear of the fluid’s
being drawn away from it altogether by the want of parallelism of
the plates ; for these, when inclined to one another at a very minute
distance, act as a capillary tube, and whisk off the water in the
direction towards which they incline.

“But,” it may be asked, “ why place the rotifer in a drop scarcely
bigger than itself?” This is done in order that the animal may be
placed, once for all, without chance of escape, in nearly the exact
centre of the compressorium, so that all the apparatus under the
stage may be brought, if need be, to bear upon it, without risk of
being impeded by the compressorium itself.

Moreover, when the rotifer has been so placed, if the observer
gets tired, or the rotifer seems distressed by having been held for
some time, the slightest slackening of the screw gives the creature
a watery cage to swim in so small that it remains safely within the
field of the objective.

If a single Pterodina happens to be placed with Alge in the
live cage, nothing can be more charming than to watch it under-
dark field illumination with a low power, but little can be learned
of its structure. The thickness of the Algee secures for it watery

EXPLANATION OF PLATE LXXII.

Fic. 1.—Under-surface of young female of Pterodina valvata.
m, mastax.
Pp, P, pear-shaped glands below mastax, and adhering to cesophagus.
q, similar glands, where the cesophagus enters the stomach,
9, 9, gastric glands.
s, stomach.
0, ovary.
v, v, v, Vibratile tags.
i, 7, longitudinal striated muscles.
t, t, transverse muscles for folding lorica.
n, n, transverse muscles for closing the slit in the neck.
c, c, dilated ends of canals of water vascular system.
2.—Side view of P. valvata.
, 3.—Dorsal view of the same, with lorica folded,
5 4.—Side view of the same; lorica folded.
» 5.—Enlarged view of the under-surface of the front of the lorica—the animal
withdrawn to show the flaps which are closed by the muscles n, n,
Fig. 1. ;
,». 6.—Trochal disk, viewed from above, and showing the two eyes.

oh Cae-ae ole

‘The Monthly Microscopical Journal Jan 11871. Pas

re nS

| Af) —~
| aS
| BS

pea West Se. Re ean W.West imp
Ptercdina Valvata.

On Pterodina valvata. 27

depths into which it dives out of reach of any but low powers ;
and, moreover, it has a habit of forcing its delicately flattened disk
between the interlacing filaments of the Alge, and of thus hiding
half its beauties from the observer.

In order to study the animal with any chance of success, it
was obvious that I ought to find, not two or three specimens, but
two or three hundred ; as then, with a score or so in the same live
box, I should be sure to find some one or other resting occasionally
on or near the surface of the upper thin glass. This July I was
fortunate enough to find a spot where Pterodina swarmed in
countless thousands; the water was alive with them. It was an
odd habitat. A large pond near Abbot's Leigh—the carp pond of
an ancient monastery—is a favourite hunting-ground of mine; it
les in a natural hollow between fir plantations, and has been
formed by damming up the course of a streamlet which runs
through the hollow. Algz grow thickly on the stones of the old
weir, and Melicerta and Floscularia are generally to be found
there with many free-swimming rotifers. I had pretty nearly filled
all my bottles, when I thought I would take a dip in the square
hole outside the pond in which the iron shaft of the weir gate
works. It is not more than a foot square, and is as dark and
unpromising a place as one could imagine; but here I found
Piterodina patina, and a new species, swarming in countless
numbers; and I have since obtained similar swarms of Triarthra
longiseta from the same place.

Now I found T’. longiseta before swarming in an open farm-
yard pond, of which the water was so coloured with manure, that
it was impossible to see through an inch thickness of it; and yet
here it throve in comparatively clean water, but in a dark hole to
which light had scarcely any access. Certainly the ways of rotifers
are puzzling.

There was a little duck-weed in the hole, and I found, when I
brought my captives home, that Pterodina delights in fastening
itself by its sucking foot to the stem of this plant; so having by a
hand lens made out a stem with a score or so of rotifers on it, I
suddenly whipped it out of the water, and placed the whole party
in the compressorium. By snipping off the green top of the
weed, and curling the stem into a circle, I had a natural cage
which held them in a moderate compass.

I do not think I ever beheld a more beautiful sight than that
which the 3rds objective, illuminated by Ross’ 4;ths condenser and B
stop now gave me. From thirty to forty of these animated fairy
shields of glittering glass were swimming in every direction across
the field, or adhering to the plant, so as to be seen from every
point of view; while some had most considerately attached them-
selves to the glass cover, and were as quiet as rotifers ever are.

+

28 On Pterodina valvata.

I could not help remarking that for rotifers possessing two more
than usually eye-looking red spots, they steered very badly, and
came very frequently into collision with each other. When too they
were holding on to the stems with their sucking disks, if one was
alarmed it instantly contracted its retractile foot, and flattened itself
close to the stem, at the same time withdrawing its ciliated head.

But my attention was now arrested by the fact, obvious enough
even under this low power, that I had two distinct species before
me. One was my old friend Pterodina patina, but the other was
a much more beautiful creature: it had a remarkably transparent
lorica ornamented round the edge with bosses placed at regular inter-
vals like those on an ancient shield, and there were two powerful
transverse muscles which I had never seenin P. patina. A mo-
ment or two afterwards I saw, to my astonishment, one of the new
species sailing by, with its lorica folded down just like the flaps of
a Pembroke table, so altering its outline that it scarcely seemed
to be the same animal. A friend who was sharing my delight in
this novel exhibition, saw the rotifer sailing first with one flap (if
I may call it so) folded down and then the other; but this I was
not fortunate enough to see, though I have seen P. valvata (as I
propose to term it) frequently with both folded at once.

Both species lived in my miniature tank for nearly a fortnight,
and swarmed so that parts of its sides looked like frosted glass: but
I noticed that they always avoided the light, and that when I pur-
posely placed the tank with one end in a dark corner, that corner
soon contained nearly the whole of them.

As I had hoped, there always were some among the number
placed simultaneously on the compressorium, that soon adhered to the
upper glass; and upon these I could bring down the higher powers.

The most striking peculiarity of the new species is the presence
of the large transverse muscles for folding the lorica. The lorica is
oval and nearly plane, except on its under-surface, along its major
axis; where it carries a sub-conical case, in which lie the greater
part of the softer portions of the rotifer.

The base of the cone is the opening from which the rotatory
head is protruded, and the lorica is here slit as shown in Fig. 5, to
give free play to the head, while the muscles (Fig. 1, n, 1) close
the flaps of the slit when the head is drawn within the lorica. At
a distance from the head of about two-thirds of the length of the
lorica, there is a circular opening through which the false foot is
protruded and withdrawn.

The water vascular system with three tags on each side can be
plainly seen; but there is no contractile vesicle. ‘There are, how-
ever, two objects (Fig. 1, ¢,¢) which appear to be expansions of the
canals, and possibly answer the purpose of the contractile vesicle: I
cannot say, however, that I ever saw them contract.

.

On Pterodina valvata. 29

Just below the mastax are two pear-shaped glands (Fig. 1, p, p)
on slender stalks attached to the cesophagus, and below these
half-a-dozen or more (Fig. 1, g) crowding round it just above the
stomach.

The gastric glands (Fig. 1, g, 7) are most singular in length
and shape, and are attached to the lorica at their larger ends.

The foot is divided into two distinct parts : the upper transversely
wrinkled and quite flexible, the lower stiff and smooth, reminding
me of a glass tube attached to an india-rubber one.

The foot ends in a curious hemispherical cup, which is lined
with long cilia extending beyond its margin, and visibly in action
as the animal swims. I can conceive of no function that they can
perform, except that of keeping the cup free from extraneous matter
which might interfere with its power of adhesion. .

The Figure 1 is that of a young female, and the ovary (Fig. 1, 0)
in consequence has an insignificant appearance, whereas at a later
stage it frequently obscures a large portion of the other organs.

The teeth are those of Melicerta, and the eyes similar to those
of Triarthra longiseta ; while the ciliated head has the two parallel
rows of cilia (the upper coarse, the lower fine), with the groove
between leading to the mouth, which are to be seen in so many of
the larger rotifers.

¢ 30)

PROGRESS OF MICROSCOPICAL SCIENCE.

Detection of Consumption with the Microscope—tIn the ‘Boston
Journal of Chemistry’ for December, Dr. J. G. Richardson, micro-
scopist to the Pennsylvania Hospital, has an important note in
which he fully bears out the views of our London physician, Dr.
Fenwick. He says that according to his own observations he has
found it useful to direct the patient to use no tobacco, to rinse out his
mouth after meals before expectorating into his cup, and to avoid
mixing the sputum of any other person with his own; in general, he
has boiled about an ounce of the tenacious sputa with their own bulk
of liquor sode in a four-ounce porcelain capsule or evaporating dish,
and, when liquefied, poured the fluid into a conical vessel containing
two or three times its bulk of water, quite slowly, to avoid cracking
the glass. Although it is by no means easy to describe the appearance
of lung tissue without the aid of drawings, perhaps most of his readers
may be able to detect its presence by the following characters, espe-
cially if they will take the trouble to mince up a piece of healthy or
tuberculous lung, and examine it as above directed after boiling in
caustic soda. Under a power of 200 diameters, the fragments of the
pulmonary air-vesicles appear to be composed of curved and curled
fibres, each about the diameter of a horse-hair, and of a shining bluish-
white colour, resembling that of the fascia lata in the thigh; their
most characteristic pecuiiarity (observed in some part of a majority of
the specimens) is the arrangement of two or more fibres in the shape
of a capital Y, with a third filament crossing from the extremity of
one arm of the letter to the other, thus presenting the appearance of
being the meeting point of the walls of three air-cells, which, when
enough of their outline remains, are each seen to have been from an
inch to an inch and a half across. The novice must be on his guard
against mistaking for lung tissue, first, small fragments of flax fibres,
which, when partly split, often assume the Y shape, but without the
cross-bar ; second, masses of Leptothria buccalis from the mouth, whose
component filaments do not appear coarser than the finest hair from
an infant’s head; third, portions of vegetable structures, whose cells
are generally smaller, while their fibres are larger and less sharply
curled ; and, fourth, wrinkles in the cell walls of boiled starch cor-
puscles, which may be detected by very close scrutiny, or by bringing
the remainder of the cell into view, by means of tincture of iodine,
or aniline solution. In addition to these suggestions, the following
remarks, quoted from his ‘Hand-book of Medical Microscopy,’ p.
210, may help some observers to escape mortifying blunders of this
nature :—“ After much careful investigation of various specimens of
sputum from both hospital patients and cases in private practice, for
the purpose of detecting some characteristics of the lung tissue by
which it could be promptly and certainly recognized, it occurred to
me that the fibres of the air-vesicles, being elastic, must break, like a
thread of india-rubber, with a square transverse fracture, while the

PROGRESS OF MICROSCOPICAL SCIENCE. 3]

filaments of any inelastic material, whether vegetable or animal, would
jray out, as it were, and present to the eye a more or less obscurely
pointed appearance. Further observation proved my hypothesis to be
correct in numerous instances; and I believe that this characteristic
of abruptly broken fibres will be found one of the most useful means
yet suggested for the recognition of pulmonary tissue in sputum.”
In conclusion, he remarks that this plan for the early detection of
phthisis is especially useful in confirming the diagnosis of obscure
and otherwise doubtful cases; in distinguishing examples of bronchitis
in the upper lobes of the lungs, where the physical signs simulate
those of tubercular deposit ; and, according to his own observations,
in recognizing those masked cases of acute phthisis which at first so
closely resemble enteric (typhoid) fever, that they have hitherto
often misled for a time even the most astute practitioners.

Cancer of the Lymphatics.—Microscopical Appearances.—In the
‘New York Medical Journal’ for November, Dr. Whitall says that
most of the lymphatic glands, the left breast, and the surrounding
indurated tissue, contained an abundance of fibrous tissue, in which
were imbedded free nuclei and nucleated cells of various shapes and
sizes. In some of the glands, and in a portion of the pancreas, the
cells predominated over the fibrous stroma. The central portion of
the various growths was in an advanced state of fatty degeneration ;
in some places scarcely anything but fat was discovered ; in others the
cancer-cells were more or less filled with oil-globules. Portions
of the pectoral muscles were reduced to mere fibres infiltrated with
cancer-cells, but contained little fat. No suspicious elements were
found in the stomach or in the nodule of the spleen. The liver-cells
were large, many of them hyaline and without a nucleus, others nearly
normal. <A good deal of free oil, but not an abnormal amount, in the
cells; no excess of fibrous tissue. Some of the tubes of the kidney
were infarcted with granular and fatty epithelium; many of them
healthy. No abnormality noticed in the tufts. There was a con-
siderable excess of fibrous tissue.

Embryology of Limulus Polyphemus.—In a recent number (vol. iv.)
of the ‘ American Naturalist, there is given with many illustrations a
most valuable paper on the above subject, by Dr. A. 8. Packard, jun.
The paper is of considerable length, but we can give an abstract to our
readers. The eggs are laid in great numbers loose in the sand, the male
fertilizing them after they are dropped. This is an exception to the
usual mode of oviposition in Crustacea ; Squilla and a species of Gecar-
cinus being the only exception known to the author to the law that the
Crustacea bear their eggs about with them. Besides the structureless,
dense, irregularly laminated chorion, there is an inner egg membrane
composed of rudely hexagonal cells; this membrane increases in size
_ with the growth of the embryo, the chorion splitting and being thrown
off during the latter part of embryonic life. Unlike the Crustacea
generally, the primitive band is confined toa minute area, and rests on
top of the yolk, as in the spiders and scorpions, and certain Crustacea,
i.e. Hriphia spinifrons, Astacus fluviatilis, Palemon adspersus, and

VOL. V. D

32 PROGRESS OF MICROSCOPICAL SCIENCE.

Crangon maculosus, in which there is no metamorphosis. The embryo
is a Nauplius; it sheds a Nauplius skin about the middle of embryonic
life. ‘This Nauplius skin corresponds in some respects to the “ larval
skin” of German embryologists. The recently hatched young of
Limulus can scarcely be considered a Nauplius, like the larve of the
Phyllopoda, Apus, and Branchipus, but is to be compared with those
of the trilobites, as described and figured by Barrande, which are in
Trinucleus and Agnostus born with only the cephalothorax and pygi-
dium, the thoracic segments being added during after-lfe. The cir-
cular larva of Sao hirsuta, which has no thorax, or at least a very
rudimentary thoracic region, and no pygidium, approaches nearer to
the Nauplius form of the Phyllopods, though we would contend that it
is nota Nauplius. The larva passes through a slightly marked meta-
morphosis. It differs from the adult simply in possessing a less num-
ber of abdominal feet (gills), and in having only a very rudimentary
spine. Previous to hatching, it strikingly resembles Trinucleus and
other trilobites, suggesting that the two groups should, on embryonic
and structural grounds, be included in the same order, especially now
that Mr. E. Billings has demonstrated that Asaphus possessed eight
pairs of five-jointed legs of uniform size. The trilobate character of
the body, as shown in the prominent cardiac and lateral regions of the
body, and the well marked abdominal segments of the embryo, the
broad sternal groove, and the position and character of the eyes and
ocelli, confirm this view. The organization and the habits of Limulus
throw much light on the probable anatomy and habits of the trilobites.
The correspondence in the cardiac region of the two groups shows
that their heart and circulation was similar. The position of the eyes
shows that the trilobites probably had long and slender optic nerves,
and indicates a general similarity in the nervous system. The genital
organs of the trilobites were probably very similar to those of Limu-
lus, as they could not have united sexually, and the eggs were probably
laid in the sand or mud, and impregnated by the sperm-cells of the
male, floating free in the water. The muscular system of the trilobites
must have been highly organized, as in Limulus, as like the latter they
probably lived by burrowing in the mud and sand, using the shovel-
like expanse of the cephalic shield in digging in the shallow paleozoie
waters after worms and stationary soft-bodied invertebrates, so that we
may be warranted in supposing that the alimentary canal was con-
structed on the type of that of Limulus, with its large, powerful
gizzard and immense liver.

American Microscopy.—At the last meeting of the American Asso-
ciation, that body taught the British Association a useful lesson in
forming the subsection of Microscopy. In this department much
valuable work was done, which we shall occupy the rest of our number
in reporting :—

A New Form of Binocular Microscope, by President F. A. P.
Barnard, of Columbia College, N.Y., who described elaborately a
newly contrived instrument in which the light is separated into two
pencils by double refraction, and which cannot fail to be a valuable
addition to the resources of the working microscopist.

PROGRESS OF MICROSCOPICAL SCIENCE. 33

On the Illumination of Binocular Microscopes, by Dr. R. H. Ward,
of Troy, suggested convenient means of regulating illumination in the
naturalist’s every-day work with the microscope, and urged that pro-
fessional microscopists make their influence more distinctly felt in
regard to the lower classes of instruments that are furnished to be-
ginners, and particularly in regard to popularizing the Binocular
Microscope.

Photographs, by Dr. Maddox, of the Podura Scale.— President
Barnard, in exhibiting these, gave an exhaustive review of the dis-
cussion in regard to the structure of the scale. The traditional “note
of exclamation,” or goose-quill markings, are unlike those of any other
known scale, and many naturalists are anxious, on grounds of analogy,
to get rid of them. Mr. Beck argued that these marks represented
parallel lines on different sides of the scale, crossing each other at an
acute angle, and necessarily imperfectly focussed ; some observers have
attributed them to corrugations or folded ridges of the upper and
lower membranes of the scale; and Dr. Pigott, with his aplanatic
searcher, and others have seemed to resolve them into bead-like rows
of spherules, between two membranes. The use of reflected light to
determine these points is very desirable, but difficult with sufficiently
high powers. Professor Smith, of Kenyon College, proposed to make
the objective its own illuminator. Others have replaced the mirror he
placed behind the lenses by a plate of glass or a prism ; but all these
means give a glare of light by reflexion from the surfaces of the lenses.
The speaker had proposed a concave mirror behind the outer pair, an
internal Lieberkuhn, which works exceedingly well with medium
powers, say one-third or one-fourth inch ; but there is not room for its
insertion in high powers. As compared with Tolles’ prism, which is
similarly situated (above the front pair), it gives more light, and
illuminates from any part or all parts of the circumference at will; on
the other hand it is less easily applied, requiring the front lens to be
mounted in glass instead of brass, and it is inapplicable to large opaque
objects. The beaded appearance has not yet been satisfactorily seen
by reflected light; nor is it well shown in the photographs where the
wedge-shaped dashes seemed rather marked by cross-lines or partial
interruptions. The speaker evidently doubted the accuracy of the
exclamation points, but was not yet ready to accept the beads. Ap-
pearances best seen by pushing an objective far beyond its ordinary
power were received with “general distrust. In the discussion which
followed the reading of this paper, Dr. Ward remarked that the pro-
duction of a beaded appearance, as a purely optical effect, should be
considered no longer doubtful, but rather an occasional accident to
persons using high powers. As an extreme instance, in the case of
a coarse and familiar structure, he related that while experimenting
upon an elater of Marchantia polymorpha, that beautiful double spiral
‘was “ resolved ” into three rows of “ beads ” or “ hemispheres,” perfectly
distinct and unmistakable, which occupied, of course, the position of
the middle and edges of the spiral. They were illuminated by parallel
light, very oblique under a {th objective of 175° worked at a power
of 3000 diameters.

D2

34 PROGRESS OF MICROSCOPICAL SCIENCE.

Diatoms thrown up by the Sea.—My. E. Bicknell, of the Museum of
Comparative Zoology at Cambridge, Mass., exhibited some diatoms
recently thrown up by the sea at Marblehead, Mass. The deposit first
found belonged to brackish water, as indicated by the nature of the
diatoms and the presence of fruit of the Characew. The second deposit
occurred about a mile from the first, and was purely of fresh-water
origin; consisting of peat with fresh-water diatoms,—Pinnularia,
Stauroneis, Navicula rhomboides, N. serians, &c. These deposits were
thrown up by a severe storm on the 31st of March last, and are
believed to be the first fresh-water or brackish deposits known to exist
under the present ocean. They seem to be conclusive proof of the
recent encroachments of the ocean upon the shore-line in that vicinity.

The Test-plate of Nobert, who has now “ gone to the war,” and Dr.
Woodward’s photographs of the same, were exhibited by Dr. Ward,
chiefly in the interest of that part of the audience who were not profes-
sional microscopists, and might be unfamiliar with these wonderful
works of human art. Until a year or two ago the finest lines had
never been seen, even by the maker of them; now they have been seen
by many persons, and have been photographed. He was now satisfied,
for the first time, after hearing Mr. Bicknell’s description, that the
Boston microscopists had seen the genuine lines with powers of only
five or six hundred diameters. In regard to the use of photography
as a test of structure under high powers and difficult circumstances,
we may learn a lesson from the broad bands of light and shade in the
photograph of the coarser lines, which manifestly have no resemblance
to the appearance of scratches on glass as seen under suitable powers.
Dr. Ward had also been investigating the effect of seeing two planes
of the object at the same time with the Wenham’s binocular. The
eye-pieces being practically not equidistant from the objective, the
corresponding conjugate foci below do not coincide. Some microscop-
ists have attributed much of the stereoscopic effect to this fact, which,
however, does not seem to contribute perceptibly (except in the lowest
powers, where the angular stereoscopic effect is necessarily very small,
and where this difference of planes is most considerable) either to the
stereoscopic effect or to the increased distinctness of definition above
and below the plane of most perfect vision.

Microscopes Exhibited—An abundance of instruments were fur-
nished by members to illustrate their discussions, or for the general
work of the subsection. The first-class stands were mostly of the make
of Powell and Lealand, and Beck, and Crouch, of London, of Nachet
of Paris, and of Zentmeyer in America. The “Jackson” model of
stand, with a curved arm, seems to be growing in favour in America ;
and it is to be hoped that those makers who have heretofore made
only one style of stand will soon offer both; so that buyers can choose
their style of stand irrespective of their choice of makers. In objec-
tives and accessories, Tolles, Wales, Zentmeyer, Grunow, Spencer,
Miller, and some other American makers were represented ; also Ross,
Beck, Powell and Lealand, Crouch, Collins, Murray and Heath, Swift
and Browning, of London; Nachet and Hartnack, of Paris; and
Gundlach, of Berlin. Very low-power objectives, 3 and 4 inch, were

PROGRESS OF MICROSCOPICAL SCIENCE. 35

deservedly popular. The use of immersion objectives for all high
powers seemed to be assumed by all members as a settled question. Few
members, on the other hand, fall into the present fashion of high-power
objectives, preferring to use lenses of 4th or ,th, and downward,
and gain greater amplification by other means than by reducing the
nominal focus of the objective.

A Micro-Telescope.—Dr. Josiah Curtis exhibited a micro-telescope,
or microscope and telescope combined, made to his order by Tolles.
It is an ordinary Cutter’s clinical microscope, fitted with an extra
tube carrying an object-glass of l-inch linear aperture and 6-inch
focus, to which objective the compound microscope acts as an erecting
eye-piece. Furnished with a proper support this makes an admirable
pocket-telescope, defining well at powers of forty or fifty diameters.

Mounting very Low Objectives.—My. Tolles had mounted a 24-inch
lens with the Society screw on each side of the shoulder, so that it can
either be screwed on in the usual position, or passed up into the body
of the instrument and fastened there, giving, by approaching the eye-
piece, about the power of a 4-inch lens at the usual distance. Micro-
scopists have been accustomed to gain a lower power than could be
focussed by their rack, by screwing a low objective into the draw-tube
and focussing upon the object through the empty nose-piece. The new
plan of a reversible mounting is more convenient, and is applicable to
instruments that have no draw-tube ; unfortunately it cannot be used
with the ordinary binoculars. The lens, though of second class, was
very good. Mr. Tolles has also arranged a 4-inch objective, in which
a short working focus is obtained by a reducing lens in the rear.
This reducing lens, for convenience, is mounted in a sliding tube, and
gives, when pushed in, a fair 3-inch power. As a 4-inch the combina-
tion is said to be extremely good. Mr. Bicknell applies this expedient
to ordinary objectives ; placing in the draw-tube, instead of the concave
amplifier sometimes used, an achromatic convex lens as a reducer, with
which an extremely low power can be obtained with good definition,
flat field, and working focus not inconveniently long. A 44 or 5 inch
lens (solar focus) may be used. A low objective of two combinations
may be divided, using one part as an objective, and placing the other
in the draw-tube.

A Clinical Compressor and Microscope.—Dr. Ward had contrived a
** clinical” compressor for use with the microscope of the same name.
The clinical microscope is very convenient for examining mounted
specimens. He had used it for years in teaching, but not much as a
* clinical.” A glass slide to hold the object, with a thin cover held
on by capillary attraction, is well for once, but does not satisfy a busy
man. It applies to too limited a range of objects; and the cover is
. Inconyenient to carry, awkward to handle, and easy to break. He had
used Wenham’s compressor until lately, but that is inconvenient under
the springs of the “clinical” stage. The new compressor is simple
(and therefore inexpensive) and can be used with great facility both
for clinical and class use, and for much of the ordinary work of the
microscopist. It is reversible, except upon a large stage, in which

36 PROGRESS OF MICROSCOPICAL SCIENCE.

case it would require a few pins to serve as legs. The want of paral-
lelism is less than in most compressors, and is not inconvenient in
clinical use. The two brass plates separate entirely for arranging the
object or cleaning the glass. The upper plate fits into a notch filed
in a ledge at the left of the lower, the centering of the two plates
being secured by a pin through the lower and a notch in the upper.
The screw which attaches them at the right is permanently fastened
in the upper plate by a groove and a pin. It has a coarse thread,
which may be cut double to screw out more rapidly, or the thread may
be reversed near the centre so that it will at the same time raise the
upper and depress the lower plate. Should a steadier motion be re-
quired, a spring may be riveted upon one plate to press against the
other. The apparatus is adjusted for a glass of jth inch below the
object and ,1,th above, cemented upon the inner surface of the brass
plates. This is strong enough to carry in the pocket safely; it can
also be used with the parabolic illuminator, or with any objective or
achromatic condenser except those of large angular aperture. Should
thin glass be required for any purpose, a glass or tin cell of sufficient
thickness to make up the difference should be cemented on one of the
plates, or both if necessary, and the thin glass fastened upon the rim
thus formed. Should no cell of suitable thickness be at hand, select a
glass cover of the required thickness, fasten it with marine glue on’ one
of the plates, punch out with a file the part corresponding to the open-
ing in the plate, and then fasten the thin glass with Canada balsam
upon this extemporized rim.

A Gundlach’s Microscope.-—Mr. E. B. Benjamin, of New York, exhi-
bited a microscope by Gundlach of Berlin. This was a small and cheap
instrument, according to the English and American standard, but
really admirable for its neatness of design and finish, and its general
excellence of performance.

A New Locality for Trocheta subviridis.—In February, 1869,
T. subviridis was found by Mr. Henry Lee, F.L.S., F.R.MLS., in the
neighbourhood of Horsham, Sussex. Now he has found it in another
locality. In ‘Land and Water’ the following account occurs :—‘ I
have now the pleasure of announcing that I have found Trocheta sub-
viridis abundant in another locality, namely, on the Beddington
Sewage-Irrigation Farm of the town of Croydon, Surrey, and I am
informed that this leech is also to be found on the other irrigation
land belonging to the same town at Norwood. The experiences of
naturalists have differed respecting the capability of Trocheta of living
for any length of time completely immersed in water. It may there-
fore be interesting if I record that I found it in about six inches of water,
at the bottom of the great ditch which conveys the Croydon sewage
on to the estate before it flows over the land, and that during the seven
weeks that have since elapsed, it has lived and thriven in a bowl of
water with two minnows.”

BE

iS)

G2RKe)
NOTES AND MEMORANDA.

A New Microscopic Lamp was exhibited by Mr. J. Browning at
the last meeting. We have not had time to examine it thoroughly,
but it appears to be a considerable improvement on those now in use.
We therefore call attention to it. We shall probably describe it in
our next issue.

Croydon Microscopical Club’s Soiree. — We alluded to this *in
our last number, but unfortunately were unable to do more. Now,
however, the Proceedings have been placed in our hands, and we are
enabled to give some account of the soirée of a Society which has not
been a year in existence (in fact, not much more than six months), and
which already numbers over 124 members, and has the good fortune of
being under the presidency of Mr. Henry Lee, F.L.S., F.R.M.S., who
is almost solely responsible for the labour involved in the recent con-
versazione. The soirée given in connection with the club on Wednes-
day evening, the 23rd ult., was a fashionable and brilliant affair; it
was not only attended by the principal families of Croydon and the
neighbourhood, but also by several persons of distinction, among whom
may be mentioned the Japanese ambassador and his secretary, who
appeared to take a deep interest in the large variety of objects which
Mr. Lee brought under their notice. Three tables, covered with green
baize, extended along the entire length of the hall, and others all along
the walls, leaving, of course, sufficient space for the visitors to pro-
menade, and examine the numerous objects of interest which were
presented for their inspection. That in the centre was reserved for
members of the Linnean Society, the Royal Microscopical Society, the
Quekett Microscopical Club, and the Old Change Microscopical Society.
The tables to the right and left of the centre were reserved for makers
of optical instruments, of whom a large number greatly contributed to
the success of the soirée by their exhibition of about 75 microscopes.
The tables around the sides and end of the hall were occupied by the
members of the Croydon Microscopical Club. The space at our dis-
posal will not permit us to enter into a description of the very nume-
rous and interesting objects that were exhibited under the hundred
and forty microscopes on the tables, but we may mention the names of
some of the gentlemen who kindly contributed to the enjoyment of the
company. Commencing at the centre table, we observed the names of
the Rey. T. Wiltshire, Captain Tyler, Drs. Mundie, Matthews, Giffard,
and Murie; Messrs. Loy, P. J. Butler, W. L. Freestone, Quick, W.
T. Rabbits, Charters White, W. 8. Kent, C. Stewart, Suffolk, Francis,
Piper, Thomas, and Brown. The manufacturers in attendance were
Messrs. Ross, Murray and Heath, Baker, Moginie, R. and J. Beck,
Collins, Swift, Bailey, Stanley, and Wheeler. The members of the
Croydon Microscopical Club exhibited in strong force. Mr. Ridley
and Mr. Cooper (coachman and gardener to Mr. Ridsdale, of Coombe-
lane, Croydon) exhibited six cases of English butterflies and beetles
most artistically arranged; and Mr. Skinner (carpenter on the estate

38 CORRESPONDENCE.

of W. H. Peck, Esq., M.P.), several cases, the designs forming the
Prince of Wales’s feathers, with the motto “Ich dien,” and two
crowns traced in small beetles. In addition to those we have
already mentioned, there was a large number of curious and valuable
articles exhibited, amongst which may be noticed contributions by
the indefatigable President, by Mr. J. F. Flower, Dr. Carpenter,
Mr. N. L. Austen, and Mr. W. J. Wilson. In addition to six micro-
scopes, Mr. Lee exhibited several curious objects, amongst which were
remarkably fine specimens of the Ewplectella (Silicious sponge) and
the Portuguese Bird’s Nest sponge (Pheronema Grayi) ; case of Chinese
insects; a chess-board, each square representing a different snow crystal
as seen through the microscope, made by the daughter of Waterhouse
Hawkins, Esq.; sections of fossil and recent nautilus, and many other
interesting objects. Altogether the evening was a most successful
one, and adequately repaid the President for the trouble he had
taken.

CORRESPONDENCE.

Tue Scares or Leprocyrtvs.

To the Editor of the ‘ Monthly Microscopical Journal.’

22, Besssoroucy Garpens, Dec. 5, 1870.

Sir,—In the report of the Proceedings of the Royal Microscopical
Society, in the December number of the ‘Monthly Microscopical
Journal,’ I read that Dr. Pigott makes me to say I have seen the scale
of Lepidocyrtus in squares.

Will you kindly afford me space to say that I never saw anything
of the kind, and did not say so; and that I cannot understand how
so wonderful a misconception could have arisen? Dr. Pigott’s remark
eet my notice at the meeting, or I would at once have corrected

im.
I am, Sir, your obedient servant,

S. J. M‘Intree.

nsoEH)
PROCEEDINGS OF SOCIETIES.*

Royau Muicroscopican Soctery.

Kine’s CoLuece, December 14, 1870.

Dr. Millar in the chair.

The minutes of the preceding meeting were read and confirmed.

The decease of the President of the Society, the Rev. Joseph Ban-
croft Reade, M.A., F.R.S., was then announced to the Fellows present
by Dr. Millar, in the following terms :—

It is my painful duty to inform you that our President is no more.
In February last he first complained of illness, which gradually in-
creased in severity so that it was with difficulty he presided at the
last meeting of the session in May; it was then his friend Dr.
Richardson examined him, and pronounced him to be suffering from
incipient cancer, in a place which forbad all hope of removal by
operation. From this time his downward course has been very
marked ; he gradually but steadily lost flesh—did not suffer so much
pain as I expected, and calmly sank without a struggle on the morning
of the 12th.

I last saw him alive on Tuesday, the 7th, when I spent several
hours with him receiving instructions with reference to various matters.
He was then very much changed, and it was clear his days were draw-
ing to a close; he spoke to me in the most calm, clear, and collected
manner, and referred to his approaching end with the utmost tran-
quillity. He took an interest in our Society to the last, spoke of the
changes likely to be made, and requested me to present in his name
a microscope which is an exact counterpart of his first one made by
Dolland, and presented to him by his father when he was 15 years old.
With it there is the highest power ,),th made by Dolland at that
time, which he had preserved ; these are interesting in the history of
the microscope as landmarks of its progress.

T have also to present six slides, mounted in brass by Cuthbert, of
Bat and Mouse hair, Podura, Lepisma and Brassica scales, together
with a piece of sphagnum ; these are quite curiosities in their way ;
they should have accompanied the Objectives he gave to the Society
when I presented the Amici microscope some time ago, but they could
not at the time be found, and it was only on this day week Mr. Lee
found them in sorting some of his apparatus for him.

Ido not know that this is the place for me to refer to it, but I
desire to add that a more calm, contented, and happy frame of mind
than he was in it is impossible for me to conceive, and I can only
wish that my last end may be like his. He will be buried on Friday,
at two o'clock.

Dr. Millar then moved, and J. W. Stephenson, Esq., seconded, that
this Society learns with the deepest regret the loss it has sustained

* Secretaries of Societies will greatly oblige us by writing their reports legibly
—especially by printing the technical terms thus: H ydra—and by “ underlining ”
words, such as specific names, which must be printed in italics. They will thus
secure accuracy and enhance the value of their proceedings.—Ep. M. M. J.

40 PROCEEDINGS OF SOCIETIES.

by the decease of its esteemed President, the Rev. Joseph Bancroft
Reade, M.A., F.R.S., who, by his scientific attainments, useful inven-
tions, and numerous important observations, rendered great service to
microscopical science; while his high character and amiable manners
endeared him to all who were honoured with his friendship or favoured
with his acquaintance.

This resolution was passed unanimously, with strong manifestations
of sympathy. It was further moved and seconded by Dr. Millar and
Mr. Stephenson, and unanimously resolved, that a copy of this resolu-
tion should be transmitted to Mrs. Reade, whose bereavement the
Society deplores,

It was then moved by Mr. Slack, seconded by Mr. Hogg, and
carried unanimously, that this meeting do now adjourn tothe usual
hour on the second Wednesday in January.

In moving this resolution, Mr. Slack said he was sure that the
feelings of those present rendered it impossible that any ordinary
business should be transacted on that occasion. Mr. Reade won the
esteem and attracted the affections of all who came in contact with
him, and every Fellow of the Society was anxious to manifest respect
for his memory.

Bristot Microscorican Socrery.

Oct. 19th.—The first meeting of the above Society for the winter
session was held on this day, being the 298th meeting of the Society
since its commencement in 1843.

After the minutes of the last meeting had been read and confirmed,
one new member was elected, and another gentleman was proposed.
Dr. C. T. Hudson then read a paper on his new rotifer, Pterodina
valvata.

Noy. 16th, 1870. Mr. R. Bernard, President, in the chair.—
The minutes of the last meeting were read and confirmed.

One new member was elected. Mr. W. W. Stoddart, F.G.S., F.C.S.,
read a paper “On the Microscopical Examination of Air, with especial
reference to the Air of Bristol.”

TunBRIDGE Wetis Microscopican Socrery.*

The last monthly meeting of this Society took place at Dr.
Johnson’s, Tunbridge Wells, on Tuesday, December 6th. The
subject for discussion was “ Water and its Impurities.”

MicroscopicaL Socrety or LiveRpoou.
(Continued from page 335, No. XXIV.)
The Rev. J. N. Berkeley says that the spores of Bunt infect all
the seeds placed in contact with them, and it has been suggested that

the plant may somehow absorb the fluid contents of the spores, and
so take in the virus. The subject, it is evident, is one of great prac-

* Report supplied by the Rey. B. Whitelock.

PROCEEDINGS OF SOCIETIES. 4]

tical importance, and one to which the study of microscopists may be
profitably directed.

After noticing Peronospora infestans, the cause of the potato
disease, the Yeast plant, and some others, he concluded by showing
what the microscope had done for Fungology, and how much remained
to be done.

In 1818, Dr. Withering described 564 species of fungi, few of
which were microscopic. There are now 2479 species enumerated,
and there are nearly one-fourth more species of fungi than all British
flowering plants together. All these, he said, had been rescued from
obscurity and confusion by the microscope, as most of the specific and
often generic characters depended on peculiarities discoverable only
by this instrument.

With a passing allusion to the Germ Theory of disease, he in-
vited the members to direct their attention to the wide field of
discovery open to them, promising to all an immediate reward in the
new forms of beauty and wonder which would be revealed to them,
and to the ambitious a favourable opportunity for acquiring distinc-
tion.

Mr. Chantrell read a communication on the Micistes crystallinus,
the result of a correspondence he had had with Mr. Henry Davis,
F.R.M.S., and the author of a paper “On Two New Species of the
Genus icistes, Class Rotifera.”

In the Report of the Proceedings of the February Meeting of the
Liverpool Microscopical Society, which appeared in the ‘Monthly
Microscopical Journal’ for April, it was stated by mistake that Mr.
Chantrell had found in the Windsor pond, at an earlier period “ Ste-
phanoceros Hichornii, Melicerta ringens, Cicistes longicornis, and
Cothurnia imberbis,” whereas it should have said, all Mr. Richter’s
specimens had been found, with the exception of the above named.
| For which the reporter is alone to blame. |

The mention of the Mcistes longicornis being found, led Mr.
Davis to make inquiry of Mr. Chantrell about this rare species, as
also about the unknown “ beautiful rotifer :” the mistake was explained,
and sketches of this latter rotifer sent, as also of young ones, and sub-
sequently some live specimens. Mr. Davis’s first impression was that
it was a variety of Limnias ceratophylli, perhaps identical with
fig. 1 in his paper, called Mcistes (intermedias) solely to suit
Ehrenberg’s classification, but he thought then and knows now that
it is a Limnias scarcely distinct from L. ceratophylli ; plate 36, fig. 2,
in Pritchard, is from one of Mr. Gosse’s early drawings, and is very
incorrect; his later figure in ‘Evenings at the Microscope’ is far
better. Limnias seem very subject to variation, the common form of
disk is double, but specimens may be taken with the constriction,
slight to another variation is in the antennz, these being mere pim-
ples developed to respectable horns in others. The young icistes,
when seen laterally, are very like the illustration in Pritchard,
minus the antenne or horns. Mr. Davis was under the impression
that Mr. Chantrell had left out the tubes in his sketches a and B, as
the tubes would have assisted him in the identification of the species.

42 PROCEEDINGS OF SOCIETIES.

Mr. Chantrell explained that in this warm-water pond the tubes dis-
appear in the mature animals, the rotifer only being very slightly
ensconced in the fork of the leaves of the Anacharis, a gelatinous
matter filling up nearly the space between the stem and the leaf, and
that it seemed more for a receptacle for the eggs than a covering for
the animal, and it is only in the very young animals that the tubes are
at all perfect.

The Floscularie found in this pond are nearly all destitute of
tubes and are of large size; the temperature of the water either dis-
solves the glutinous matter of the tubes, or the animal, finding the
temperature agreeable, will not trouble himself to build a tube.

Mr. Davis expressed himself quite satisfied that the specimens ~
sent to him by Mr. Chantrell were Cicistes crystallinus (Ehrenberg): the
fact that the tube is irregular and undeveloped is curious, but scarcely
a specific characteristic, while the animal itself seems identical with
CEcistes crystallinus pure and simple. Does not the warmth of the
water influence the secretion and deposition of the tube materials?
He thought Mr. Chantrell would not be able to reconcile his opinion
with the account of cistes crystallinus in Pritchard (after Ehren-
berg), still less with the figure in the same book. Look at Ehrenberg’s
description and figures of better-known rotifers, as Melicerta, Stepha-
noceros, &c.; note the inaccuracies and be not surprised at a few more
discrepancies. Mr. Davis states that a few years ago Mr. Gosse was
so kind as to help him to identify this species, otherwise he would
have never guessed what the rotifers were, which at that time he
took in great abundance. In the matter of the tubes or cases, Mr.
Gosse’s takings and his did not agree; Mr. Gosse’s had nearly opaque
tubes, but his were clear and colourless, whilst Mr. Chantrell’s seem a
mixture, as if the creature tried both systems and then gave up tube
building in disgust.

Mr. Chantrell pointed out a marked characteristic in the mature
specimens of the (cistes ecrystallinus, which is the second row of
cilia carrying the food in right and left currents to the gullet or
mouth ; this does not show in the young specimens, which are always
in tubes, but as they get larger the tube gradually disappears.

Mr. Davis stated the fact that in all this division of rotifers the
mouth is outside and beneath the disc; that they have all more or
less developed the second row of cilia: it was first noticed by Pro-
fessor Huxley in Lacinularia, the first row at the edge of the disc
seeming to have no directive power, merely stirring up the food in
the water, whilst the second row (outside and under disc) appears to
conduct the floating matter to the gullet.

Mr. Chantrell said he was not satisfied of this and was making
further investigations, and hoped at a future meeting of the Society to
give the result; he had however detected the cilia on what Mr. Davis
in his paper on CMcistes intermedia, terms the ciliated projection or
chin through which the ejected food was discharged. :

The Rev. W. H. Dallinger exhibited Woodward’s tank microscope.

Mr. A. Higginson, M.R.S.S., exhibited some sections of tape-worm,
showing the ovaria and ova in situ.

PROCEEDINGS OF SOCIETIES. 43

Mr. Thomas Higgin, some photographs of Atlantic soundings;
and

Mr. T. J. Moore, the spawn of Siredon axolotl, an inhabitant of
fresh water from Mexico.

The usual conversazione concluded the proceedings.

BricHton AND Sussex Natrurat History Society.

October 27th.—Microscopical meeting. Mr. T. H. Hennah, Vice-
President, in the chair.

Mr. R. Glaisyer announced the receipt of twelve slides for the
Society’s cabinet from Mr. Wonfor.

The minutes of the previous meeting being read, Mr. Hennah
called attention to the facility with which sections of bone could be
made and mounted by Dr. Ormerod’s process, and Mr. Wonfor re-
marked that the process applied equally well to such objects as the
stones of fruits and shells of nuts. Its great advantages over the
other methods were its simplicity and rapidity; he had made and
mounted sections of bone and other hard substances in twenty minutes
—a great saving of time compared with the ordinary methods, which
often involved hours, without giving so good results.

Mr. Hennah then introduced the subject of the evening, ‘ Tlumi-
nation,” by remarking that more depended on proper illumination than
on the instrument or objectives; good objectives without proper
illumination failing to show a proper performance, and inferior ones
being made to do a great deal. In the illumination of objects by
transmitted light, whatever the apparatus employed, the rays must be
parallel. By paying attention to this, almost any structure could be
made out by the mirror alone, without the expensive sub-stage appli-
ances recommended by the opticians. The angle of illumination
should never be excessive, in fact should not exceed 90°; otherwise
confusion resulted. Whatever the sub-stage appliance, the light should
be exactly focussed on the object. For thick substances direct rays
were necessary, but for thin and lined objects oblique rays were
essential. The various modes of sub-stage illumination, such as the
ordinary and flat mirror, the Nachet and Amici prisms, the achromatic
condenser, and the Reade’s prism, were each discussed, preference
being given to the Amici, when the sub-stage admitted of its appli-
cation.

Mr. Wonfor then described the different methods for illuminating
opaque objects or for obtaining dark-ground illumination, such as the
bull’s-eye condenser, the Leiberkuhn, parabolic illuminator, Wenham’s
paraboloid, &e.

The various methods were afterwards illustrated by Messrs.
Hennah, Wonfor, and Dr. Halifax.

It was announced that the subject for November 24th would be
“Bone and Allied Structures.”

November 10th. Ordinary meeting. Mr. Sewell, Vice-President,
in the chair.—Mr. Colborne was elected an ordinary member.

The Hon. Sec. reported the receipt of the ‘ Annual Report and Pro-
ceedings of the Belfast Naturalists’ Field Club’ from the Hon. Sec.,

44 BIBLIOGRAPHY.

and the Annual Reports and Journals of the Quekett Club from the
commencement, from the Hon. Sec. of the club.

Mr. J. Howell read a paper “On Excavations through the Post-
Pliocene of Brighton.”

Mr. Mayall reported on the successful issue of his invitations of the
town authorities and the society to the British Association, which had
named Brighton as the place of meeting for 1872.

Reapina MicroscopicaL Socrery.*

December 6th, 1870.—Dr. Shattle read part of a communication as
to the action of electricity in the development of nerve-cells; and
having referred to the observations of John Hunter, Lister, and
Richardson upon coagulation of the blood, to the remarks of Lee and
Pettigrew upon the spiral arrangement of nerves and layers of the
heart, and to Dr. Beale’s descriptions of the nerve-cells of the frog,
proceeded to give particulors of his own experiments and theory.

Captain Lang exhibited selected specimens of various Diatoms
obtainable in Primary Peat; the greater number being Pinnularie, as
P. nobilis, P. major, P. acrospheria, P. viridis, P. gibba, P. divergens,
P. interrupta, P. lata, P. alpina.

Mr. Tatem showed Difflugie, symmetrically mounted, and Mr.
Austin exhibited the mycelium of Peziza ceruginosa in green oak-
wood.

BIBLIOGRAPHY.

Anatomja patologiczna. Wydame biblioteka umicjetnosci lekars-
kich. W. Brodowski. Bd.I. 1 Halfte. Warszawa.

Botanische Untersuchungen iiber die Alkoholsgahrungs pilze.
Mx. Rees. Leipzig. Felix.

Bryologia Javanica seu descriptio muscorum frondosorum archi-
pelagi Indici iconibus illustrata. Fasc 61-63. F.Dozy und J. H.
Molkenboer. Lugduni Batavorum.

Annales musei botanici Lugduno Batavi. Edidit F. A. Miquel.
Tom. IV., fasc 9. Amstelodami. Leipzig. Fr. Fleischer.

Abhandlungen der naturforschenden Gesellschaft zu Halle. 11
Band, 2 Heft. Halle. Schmidt.

Bulletin de Académie Impériale des Sciences de St-Pétersbourg.
Tome XV. 36 feuilles. Leipzig. Voss.

Ueber die wachsende Kenntniss d unsichtbaren Lebens als
felsbildende Bacillarien in Californien. Von Dr. C. J. Ehrenberg.
Berlin. Diimmler.

* Report supplied by Mr. B. J. Austin.

——

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THE

MONTHLY MICROSCOPICAL JOURNAL.

FEBRUARY 1, 1871.

I.— Observations on the Use of the Aéroconiscope, or Adr-dust
Collecting Apparatus. By R. L. Mappox, M.D.

(Read before the Royau Microscoricat Society, Jan. 11, 1871.)
Puares LX XIII. anp LXXIV.

Tue use of the instrument described and figured in the Monthly
Journal of the Royal Microscopical Society, June Ist, 1870, for
collecting, through the natural force of the wind, particles floating
in the atmosphere, and which is now designated the Aéroconiscope,
enables me to offer a brief sketch of some of
the results obtained, also to extend the plan of
cultivating the germs collected on the thin
covers.

Wishing a more simple method of forming
the air-space than with the tinfoil arrangement
previously described, a preparation of mastic,
wax, chloroform, &c., was made, which, by aid
of a small sable-brush, would be drawn across
the surface of a very slightly-warmed slide, so
as to form a square, the size of the thin cover,
but with one side prolonged to the edge of the
slide, and the other brought nearly to meet
that side, and then turned down also to the
edge, so as to allow a small channel for the
entrance of air. This method answered the
purpose, the covers, by a very gentle pressure
along the edges, remaining well fixed on the
cement. Also, to form a simple damp culti-
vating chamber, to contain a number of slides
at once, a large new ordinary writing-slate,
"with a well-made frame, had the latter deep-
ened on one surface by an extra frame about
one-sixth of an inch thick, and furnished with a couple of cleets
at two ends, with a stop or check on a third side. After well
cleaning the slate, a leaf of thick white blotting-paper was laid on

VOL. V.

46 Transactions of the

the surface, and on this a sheet of cleaned pierced zinc the size of
the slate tablet. The blotting-paper was damped with distilled
water, the piece of pierced zinc placed on it, and a sheet of clean
flat glass pushed along the grooves in’ the cleets at the two ends
up to the stop on the opposite side of the frame, so as to form a
close cover to the thin flat slate-box. When the slides had been
examined and memoranda made in ink on their free surfaces, they
were placed in this chamber, and exposed to the diffused light of
the room. The slate-box, holding twenty-one slides, was easily
managed, and the blotting-paper damped when necessary by dis-
tilled water from a dipping-tube, always trying to avoid adding
too much.

The cultivating solution used for the thin covers and the slides
at the commencement varied, but preference was given to the fol-
lowing :—

Thick clear treacle, 1 drachm ;

Saturated solution of acetate of potash, 40 minims ;

Distilled water, 5 drachms ;
boiled in a narrow covered test-tube until reduced to 4 drachms,
then closed whilst hot, allowed to cool and settle, a portion being
poured off into a clean two-drachm stoppered bottle that had been
previously washed out with alcohol, and dried.

Another solution was tried, which contained the same ingre-
dients, plus 6 minims of liq. Am. fort., and boiled slowly until all
trace of the smell of ammonia was absent.

A clean bent needle was employed to convey enough of the
solution to smear the centre of the thin cover for about one-sixth of
an inch, and to place on the slide, when set up for cultivating, a
droplet of the same solution the size of a small pin head.

Ist. The position chosen for the apparatus was the supposed
best one the locality permitted, yet not such as to be equally ex-
posed to wind from every direction of the compass, being somewhat
protected from the §.8.W. and W. winds by the house; and as the
garden is surrounded by a low wall, some diminution of the force
of the wind might be expected; hence fewer particles entrapped,
though with every slight breeze, from any quarter, the instrument
revolved freely, the average height of the centre of the vane being
five feet.

2nd. There appears to be no relation between a prevalence of
germs with the wind from any one point of the compass more than
another that was at all decisive, for what seemed to give such ex-
cess at one time was neutralized at others.

Nor could any relation be established between the force of the
wind and the quantity of spores, though there was abundant proof
of the greater crease of dust in the air when the ground was not
wet. This is attributed to the light germs being carried higher

Royal Microscopical Society. 47

than the mouth of the apparatus. A gentle breeze was the most
productive.

3rd. The amount of spores collected on the surface of the thin
glass varied from 250, the largest number counted, to one, and
ranged through 112, 87, 60, &c., to the minor number, some days
not furnishing one to be seen, on a careful examination with a 4th
objective.

4th. The prevailing spores were small pale olive-coloured oval
spores, accompanied often with a small round rather darker olive-
coloured spore (Figs. 8, 26, 30), both apparently some form of smut.
Of the varieties of germs, &c., including chlorococcus, and what is
considered not a spore, but a cellular hair of some plant, though
figured, only 46 were noticed, and some of these are evidently two
or more phases of the same spore. The colour in the drawings has
been adhered to as strictly as possible, and the drawings made by
aid of the camera lucida at 300 diameters, as also the results figured
from a to 2, obtained by cultivation.

The number of days of exposure was 155 (19 in April, 24 in
May, 23 in June, 19 in July, 10 in August, 22 in September, 26
in October, 12:in November). The months of July and August
furnished by far the largest proportion of the daily collections.
The hours of exposure, except as intimated, may be taken during
Det days as 10 to 11 hours, and the short days from 8 to 9

ours.

In some cases the spores were seen to commence germinating
on the second day, others not before the twentieth day, and many
apparently of the same appearance under the microscope and on
the same thin glass did not germinate at all; nor could it be said,
without trial, which was or which was not capable of growth or
living. Some of the spores which germinated quickly, early put on
a sickly aspect, whilst others, of apparently the same sort, grew
vigorously in the same cell.

In very few cases the fungi formed their heads of spores or
conidia in the open air-chamber around the droplet of the culti-
vating solution, as some form of penicillium, whilst others did not
push their spore-bearing stems or fertile filaments beyond the edges
of the liquid, though the branchlets of the mycelium were often
extended to the edge of the cell. In some cases when the little
drop of fluid had receded from a thread and left it exposed to the
moist area only, it had the appearance of having its surface provided
with minute rootlets or hairs, as in Fig. u, and if left for any
time, it seldom recovered, by a change in position of the droplet or
by increased moisture admitted from the cultivating box, either its
original healthy condition or arrangement of the protoplasm.

During the very hot days there was some difficulty in keepmg
the quantity of the droplets of fluid constant by the supply of

E 2

48 Transactions of the

moisture in the cultivating chamber, and there was great inequality
as to this in the different cells, though without any very apparent
reason.

5th. Many of the cells were closed at some definite stage of
growth of the contents by being cemented all round, yet the myce-
lium often continued to spread, hence others were purposely checked ,
by the admission through capillarity at the small open space of
the cell, of a little saturated solution of acetate of potash; but the
entanglement of the mycelial threads was often so rapid, as in a
short time to obscure the germinating spore under observation, and
the threads so commingled they could not be followed back to their
primary source. During absence from home, some days in August,
also occasionally on account of the extreme violence of the wind,
rain, or other reasons, the apparatus was not set up, and occasion-
ally on account of wet was removed for part of the day: in one case
it was left out all night, otherwise the exposures were only during
the day-time. Once the same cover was used twice, ¢.e. on the
following day. There would be little use to try and tabulate the
amount of spores obtained per diem or per hour, for the apparatus
embraced no method for recording the velocity of the wind, hence
it would be impossible to estimate the quantity of air that traversed
the instrument within a given time. Suffice that the conditions
were simply those which, without any augmentation or decrease,
any person would be exposed to on the same spot and turning to the
course of the wind, though with the difference between the areas of
the breathing apertures and the open or arrow end of the vane. The
results show that the chances if an aspirator had been used on
various and not successive days, or even upon parts of the same
days, that no reliability as to the natural quantity of dust or spores
at that height from the ground would have been obtained, and the
present report only furnishes the amount of those gathered in the
day-time, except on one occasion, hence it is necessarily incomplete
for the twenty-four hours. The septate spores (Fig. 11, and m)
were of frequent occurrence and germinated freely, but without
furnishing any secondary spores. Whilst in various cultivating
cells some minute bodies, figured at d, 0, and s, suddenly as it were
made their appearance, and are I believe gonidial forms of one
of the fungi or zoospores put forth under unnatural conditions:
some germinated to the extent of throwing out fine branches of
mycelium, which I think is not usual, as in Fig.d. The minute
bodies, figured at 0, had a slight movement, but no cilia could be
detected, nor had they the form of bacteria or monads, but were
most likely gonidial bodies emitted by the terminal, though free
conidia, seen near to them.

‘lo conclude this imperfect sketch of the result of the employ-
ment of this form of aéroconiscope, it may be briefly said that it

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Royal Microscopical Society. 49

fulfilled its purpose well, was exceedingly easily managed, and
might, if connected with the usual meteorological instruments at
our observatories or other institutions, gradually enlarge our know-
ledge of the chances of such or such germs being either directly or
indirectly related to those atmospheric conditions usually associated
with various epidemics. The employment of this one has afforded
results sufficient to establish the utility of the apparatus, which, if
for continued use, should by preference be made of thin sheet copper
or iron, enamelled on both surfaces, especially the inner one, to
diminish the chance under light breezes of the dust, &c., resting
against the inner surface in the transit of the air through the
instrument. Also that it should be exposed day and night, pro-
tected, if possible, from the rain. If found too heavy to rotate easily,
though, if nicely balanced, there would be little chance of this, the
side funnels might be omitted; yet as the apparatus revolves some-
times rapidly, or in advance of the direction of the wind, they are
useful. If absent, it would be almost requisite to limit the rotation
by a spring pressure that should be called into play according to
the force of the wind, so as to steady the vane more or less, yet
leave it free to rotate under less wind, or more gentle breezes,
without any hindrance.

Note.—No attempt has been made to name the various forms gathered from
the air or the results obtained by their cultivation, as the abnormal conditions
under which they were produced might have considerably altered their common or
natural appearance. It has been deemed best to simply give the results in figures
for comparison, in case this interesting study be earnestly pursued by others; yet
the absence of colour in the Plates will render even this more or less difficult,—
for many of the spores are so nearly of the same size and shape, though differing
in colour, they may easily be confounded ; also the colour of the mycelium, which
may help to distinguish some of the forms from each other, I found to vary con-
siderably with the medicine in which they were grown, so that in the absence of
the spore-bearing stems or heads, considerable difficulty must occur in correctly
naming or comparing the figures. This will furnish some apology for the few
allusions to the figures in the letterpress. The chief object being to prove the
utility of the apparatus in the first instance.

50 Transactions of the

{I.—On the Employment of Colloid Silica in the Preparation of
Crystals for the Polariscope.

By Henry 8. Sracs, F.GS., Sec. R.M.S.
(Read before the Royau Microscopican Soctery, Jan. 11, 1871.)

I xatety called the attention of the Society to the nature of the
cracked films obtained by slowly, or quickly, evaporating a dialyzed
solution of colloid silica in distilled water. As these films solidify
they crack in various directions, and make complicated patterns of
straight and curved lines, sometimes appearing like the plan of a
city, and at others assuming curious columnar forms with trans-
verse striations. It is also common to find slight changes in the
level of different parts of the films, sufficient, as explained in a pre-
vious paper, to exhibit Newton’s rings in a very beautiful manner.

It seemed probable that by dissolving crystallizable bodies
suitable for exhibition with the polariscope, in a solution of silica
instead of in plain water, some interesting modifications of crystalline
patterns might be obtained. Using sulphate of copper in this way
afforded the following results. First, what may be termed a “ pave-
ment pattern,” in which the silica cracks divide the film into a
great number of small compartments of three, four, five, or more
sides, which may be roughly likened to the appearance of vegetable
ivory, or a section of pinna shell. In each of these divisions erys-
tallization takes place, usually radiating from the centre, and suffi-
ciently diversified in thickness or position to produce polariscope
patterns that remind me of a richly and variegated pavement, devia-
ting from “tesselation,” imasmuch as the compartments are not
squares. The crystals thus reduced have a tendency to exhibit
Maltese crosses of colour, changing with the positions of the polar-
izing and analyzing apparatus.

In these “pavement patterns” the force exerted by the silica
films in contracting and cracking, causes the crystalline force to
operate in limited compartments without change im the linear
direction, common to radiating groups.

In other cases the contractile force acts tangentially, or im curyes,
while the crystalline force operates radially, and then we obtain exqui-
site spiral and turbinate forms, very similar to those which Mr. Thomas
brought before the notice of the Society in 1866, and which pro-
bably resulted from an analogous combination of contractile and radial
forces operating so as to give curved resultants. Ifa number of
trials are made with different modifications of the temperature and
times of drying, all sorts of conflicts between the two forces will be
found to occur. One very instructive instance supplied a pat-
tern commencing with circles filled with radu, and marked with

Royal Microscopical Society. 51

concentric rings, after which the radii became spirally twisted and
plumose, and terminated in straight lines, regaining, their normal
direction. Several of the gyrating portions had the appearance of
spirally twisting about their own axes. This aspect probably
resulted merely from the arrangement of colour, light, and shade
obtained by the action of polarized light.

In other cases feather and landscape effects were obtained,
owing a good deal of their richness and diversification to the silica
cracks and changes of level.

By dissolving salicine in the solution of colloid silica—aiding the
operation by heat—something like the pavement pattern of the
copper slides was occasionally obtained, each compartment being
filled with a beautiful group of crystals assuming the shape of a
pink, or some such flower. At other times the circular and radial
patterns so well known to microscopists were modified by the radu
becoming plumose, and more or less curved. In a few instances a
very elegant fan-shaped and extremely delicate crystallization sprang
from solid crystals like fan-handles, the fan portion being decorated
with concentric rings, and terminating in a border of fine needles,
looking like a silken fringe, and appearing under suitable illumina-
tion to be in a different plane from the fans themselves.

Hippuric acid similarly treated yielded flower patterns of great
beauty, some of them taking the form of what the botanists call a
ringent corolla. These are usually of extreme delicacy, and only
seen well in one or two positions of the polarizing apparatus.*

Tartaric acid used in the same way gives irregular pavement
patterns, some of the compartments looking flat, and of more or less
uniform tint, while others appear slightly raised and ribbed, bearing
some resemblance to coloured acorn-barnacles. The actual varia-
tion of level in these cases is very slight; far less than what the
perspective action of shade and colour would make it appear.

All these crystals require careful management of the polarizing
apparatus, and a selenite stage to bring out their full beauty. The
“neutral tint stage” of Mr. Ackland shows them extremely well.
When properly displayed it will be found that crystals prepared in
this way afford a greater range of colour than is common, and the
artistic defect arising from too violent contrasts is avoided. The
observer should not be satisfied unless the primary tints are asso-
ciated with a sufficient variety and quantity cf secondary and ter-
tiary tints to produce a true chromatic harmony.

It is impossible to view a number of slides prepared in this way
without being struck with the resemblance of many of the patterns
to those of sections of various structures in organized beings, and we

* Quite different patterns were obtained on other occasions. The author hopes

shortly to bring before the Society, and publish in this Journal, illustrations of
some of the most remarkable forms obtained with different bodies.

52 Transactions of the

are led in the direction long since indicated by Mr. Rainey to
extend our notions of the functions performed by the chemical and
physical forces at work, according to their own methods, in living
things. The action of the silica in the cases cited seems to be
chiefly physical and mechanical, but the appearance of the crystals,
especially when viewed under considerable magnification, leads to
the belief that some portion of the silica is present in them and
not eliminated as the process of crystallization goes on. Other
methods have been long practised by microscopists to modify erystal-
lization, and which appear to depend upon the same principle of
offering resistance to the normal action of crystalline force. One
advantage of employing silica, as described, is that we can obtain a
number of interesting patterns with films of that substance alone,
and compare them with the varieties of crystalline patterns obtained
from simple aqueous solution, and with those producible from the
mixed solutions. Fellows of the Society experimenting in these
directions, will do well to examine the beautiful slides of various
crystals prepared by Mr. Norman, which will be found in the
Society’s cabinet.

Royal Microscopical Society. 53

IlI.—The Development of Phycocyan.
By Tuomas Cuarters Wurtz, M.R.C.8., L.8.D.
(Read before the RoyaL Microscopicau Society, Jan. 11, 1871.)
Puate LXXYV., Upper Part.

THERE are many present, doubtless, this evening who may re-
member the interesting specimen of Dichroic Fluid exhibited upon
two occasions by our late esteemed President—one obtained at
Canterbury, by Mr. Sheppard, and the other by Mr. B. D. Jackson,
from a pond at St. Leonards; these fluids, as you may remember,
presented the peculiarity of looking red by reflected ight, and blue
by transmitted light. I do not know if either of these gentlemen
saw the process of development of this Dichroism, but I have had
the opportunity of watching its gradual growth, and desire in this
short communication to lay before you its life history as I observed
it, and then leave to others the explanation of its origin and the
theories deducible from it.

About the early part of November, having some friends coming
to spend a microscopical evening, and being desirous of exhibiting
something living for their amusement, I sent to a favourite hunting
ground of mine, the Round Pond in Kensington Gardens, where
often floating portions of Myriaphyllum and such-like aquatic plants
afford abundant game for the microscopist; but, alas! Boards of
Health, and such-like bodies, being inimical to everything but clean-
liness, had shot in plenty of clean gravel, and no weeds could be
detected: where Floscularia and Bacillaria had before been found in
plenty, nought could be gathered but some green flocculent matter,
which settled at the bottom of the collecting bottle lke green
cumuli clouds. Upon placing some of this under the microscope,
the green matter was seen to be made up of moniliform strings of
cells, coiled up to the extent ofa turn and a half, and of a pale
green colour: mixed with these were several bundles of fibres of an
ochreous colour, looking like dead bundles of Bacidlaria paradoxa,
arranged in a slightly fan-shaped form (Fig. 2): animal life appeared
almost absent, and was represented by a few monads. Not thinking
this worth exhibiting to my friends, I screwed down the top of my
York bottle, and stood it on the window-ledge inside my room, and
it was there forgotten for about a fortnight, when by chance look-
ing up at it, I saw that the green flocculent matter had descended
to the dead level of some yellowish-coloured mud, but for about a
quarter of an inch above it was a layer of the deepest richest indigo
blue I had ever seen. Taking it down carefully, so that no disturb-
ance of it should take place, I looked at it by reflected light, when
it was a rich crimson lake. I then remembered the Dichroic Fluids

54 Transactions of the

I had seen here, and in which the late Reverend President had
taken such an interest, and I made a careful microscopical exami-
nation of this specimen, and communicated the following results to
him. On removing the stopper of the bottle an opaque semi-gela-
tinous film covered the surface of the water: upon examination it
appeared full of minute granules; While round its semi-globular
masses, Paramecia in every size and stage of growth were spoMing
and voraciously feeding (Fig. 1).. The layer of blue contained no
life, nor any particles of an appreciable size, while the mud seemed
nothing else than the disintegrated particles of the green spirals
of a fortnight ago. After the uncorking of the bottle and this
microscopical examination the blue colour became diffused, and the
Dichroic character of the fiuid became like that brought to this
Society. I wrote to the late Rev. Mr. Reade, giving him this life
history of Phycocyan, and at his wish I bring it before the notice
of the Fellows. About a fortnight after this I examined the fluid,
when it teemed with Vibriones; all the Dichroic appearance had
gone, and the Paramecia had disappeared, but it had been closely
corked, and having no yegetation to -aérate the water, they were
probably killed. Upon a recent examination of the sediment
abundant Amcebiform bodies were seen in all sizes, and animal life
of a low form was very abundant, but for the last week or so the
bottle has remained indoors uncorked, thus affordmg air for the
development of life. I leave the explanation of this colour to
others, and only state the facts as they appeared to me.

BIsHOPsBOURNE Recrory, Wov. 19, 1870.

My pear Mr. Wurre,—Pray send a note without delay to the
Microscopical Journal, describing «your interesting experiment upon
Phycocyan, which entirely confirms my views and Mr. Sheppard’s as
described at the last meeting. The fluid consists, as you also show,
of opaque red particles and the blue solution. Your coloured solution
was formed without the addition of albumen, as was also Mr. Shep-
pard’s in his first experiment, where the albuminous eggs supplied
what was wanting, as is the case in your experiment: so we may say
that the simplicity of Phycocyan depends upon its duplicity.

I return your two drawings, that you may have them engraved on
wood. With many thanks,

Believe me very truly yours,
J. B. Reape.

(P.S.—You might send this note to the Journal, as a preface to
yours. Iam so weak that a friend writes for me.—J. B. R.)

The Monthly Macroscopical Journal Fehl 1871.
=

Tuffen West se.

W.West £Coamp.

Royal Microscopical Society. 55

IV.—The Anatomy of the Round-worm.
(Ascaris lwmbricoides, Linn.)

By B. T. Lownz, M.R.C.S. Eng.

(Read before the Royat Microscoricat Society, Jan. 11, 1871.)
Puates LXXYV. anp LXXVI.

~ Tue anatomy of the Nematoida still remains in the greatest obscu-
rity, although Cloquet, Otto, Meisner, Schneider, Dr. Bastian, and
others, have contributed largely to the literature of the subject.
Numerous contradictions are found in their works, and much that
is unsatisfactory remains to be cleared up.

About four months ago I was fortunate enough to obtain fifty
or sixty large round-worms from a patient, who was the host of
nearly two hundred of these parasites. I thought this was a fa-
yourable opportunity to endeavour to clear up the more important
points in the anatomy of the Nematoid worms. The result of my
investigation has been most satisfactory to myself; and although I
differ in my conclusions from all previous writers, I have not hesi-
tated to publish the results of my inquiry, as, if I am right, my
observations throw an entirely new light upon the anatomy of the
Nematoids, and establish their place in the animal kingdom in a
most satisfactory manner.

The Ascaris lumbricoides resembles an earth-worm at first
sight. The female varies from ten to sixteen inches, and the male
from five to eight inches in length. The extremities are tapered ;
the anterior extremity being more so. The alimentary canal runs
straight through the animal, the mouth and anus being situated at
the extremities. There is a distinct space between the body walls
and the alimentary canal,—the body cavity,—filled with a pink
serum-like fluid, in which the organs of generation lie. This fluid
keeps the external walls tense, and escapes with a gush when they
are ruptured. The duct of the female generative organs opens on the
ventral surface, at the junction of the anterior and middle thirds of
the body: that of the male has its orifice very near the posterior
extremity. A pair of curved spicules, retracted when at rest, con-
stitute the armature of the male generative aperture, one being
placed on either side of the opening.

The body wall consists of the integument and of a thick layer
of longitudinal muscles beneath it.

The integument exhibits two diverse layers, an external chiti-
nous and transparent, and an internal cellular portion. The external
layer is indistinctly segmented, exhibiting many hundred annuli.
This layer is apparently structureless, but may be split up into
numerous layers, a fact first pointed out by Czermack. It presents
no trace of celluiar origin, and I am inclined to look upon it in the

56 Transactions of the

same light as Dr. Cobbold, as being probably an excretion of the
inner cellular layer, which consists of small granular-looking cells.

Immediately beneath the integument is a thick layer of longi-
tudinal muscles. The muscular fibres (Plate LXXYV., Fig. 3) are
about sioth of an inch in diameter, non-striated, nebulous, and
occasionally exhibit nuclei at intervals. They are dissolved rapidly
by moderately strong acetic acid, and, like all the tissues of the
Ascaris, are very elastic.

I have been unable to detect any transverse layer of muscle,
although Cloquet has described such a layer, and I suspect with Dr.
Cobbold that the annular striation of the integument has given rise
to the opinion that such a layer exists.

The mouth is surrounded by three lips, emarginate in front
(Fig. 4). The external chitinous layer of the integument is con-
tinued into the thick muscular pharynx, which it lines. It is thrown
into three ridges which alternate with the lips (Fig. 5), and which
are covered with sharp-pointed tubercles, forming three very effec-
tive pharyngeal teeth. Fig. 6 represents the rounded anterior
extremity of one of these ridges. The exterior of these ridges,
which are prolonged to the posterior extremity of the pharynx,
gives attachment to the transverse muscular fibres of the pharynx,
so that these are divided into three sets.

Several slighter ridges run transversely across the main ridges,
and probably give attachment to some of the numerous longitudinal
muscular fibres of the pharynx. The fibres of the pharynx are less
than half the diameter of those of the body wall, but are, like them,
non-striated.

I have been unable to detect any muscle in the alimentary
canal below the pharynx, which appears to consist of an external
chitinous layer lined with epithelium. In this respect it is precisely
hike the inner layer of the intestinal canal of an insect. I strongly
suspect that the rough surface of-the ridges of the pharynx is
epithelial, and that the pharynx is elsewhere lined with epithelium
similar to that in the remainder of the intestinal canal, but I have
been unable to observe this satisfactorily.

I would point out some remarkable affinities with the abranchiate
annelida, exemplified in the three pharyngeal teeth and the seg-
mentation of the integument, which is very similar to that in the
leech: these seem to indicate a closer affinity than has hitherto
been recognized.

One of the first points which attracts the attention of the most
casual observer in the external appearance of Ascaris is the presence
of four longitudinal white or pinkish lines or bands running the
whole length of the animal. These have been incorrectly described
by numerous observers as muscles, and Dr. Cobbold has fallen into
the singular error of speaking of them as the “only muscles in

Royal Microscopical Society. 57

Ascaris,” although Cloquet has correctly described the longitudinal
layer of muscles. Similar bands occur in Mermis, Gordius,—and
indeed, in all probability, in all Nematoids, as well as in Echino-
rhynchus, &c.

On careful examination it will be at once seen that two of these
lines are much broader and more conspicuous than the others: these
are lateral in position. The narrower lines are dorsal and ventral,
the ventral line in the female deviating from its course and passing
on one side of the sexual orifice, not dividing and surrounding it,
as is stated by Cloquet.

The alimentary canal behind the pharynx in the anterior por-
tion of the body is stretched across from one of these lateral bands
to the other, but in its posterior two-thirds it is merely suspended
in the body cavity and surrounded by the conyolutions of the ova-
ries in the female, and of the testis in the male.

This condition of the anterior portion of the alimentary canal is
of considerable importance when viewed in relation to the condition
of the bands and alimentary canal in Mermis. In Ascaris I have
failed to trace any nearer connection between the alimentary canal
and the lateral bands than, that the alimentary canal is connected
with the body walls at these points by connective tissue of extreme
tenuity. I am inclined to the belief that the whole body cavity is
lined with an extremely thin membrane which is reflected upon
the intestine at these points. It will be necessary hereafter to
refer again to this relation of the lateral bands and alimentary
canal.

The anus is situated at the posterior extremity of the body,
and the alimentary canal is usually filled with dark-coloured chyle.

In these preparations* the whole interior of the body cavity will
be seen to be covered with white villi-like processes; these are the
appendices nouricieres of Cloquet, and when examined with the
microscope are seen to be pyriform vesicles, which are filled with a
white molecular fluid. They are supported by ducts which form a
complicated network over the whole inner surface of the body wall.
If a transverse section of the worm be made, this network of tubes
may be seen to be connected more closely with the body wall at
four points than elsewhere ; that is, they are connected with the
four longitudinal bands above described.

The dorsal and ventral bands appear to be the main trunks of
this system, and to give off lateral branches at short intervals,
which support the vesicles themselves. Plate LXXVI., Fig. 2,
represents a portion of one of these trunks with its lateral ducts
and vesicles. A section of the worm is accurately represented in
Schneider’s ‘ Monograph on Nematoids.’

* The preparations here referred to have been presented by the writer to the
Museum of the Royal College of Surgeons.

58 Transactions of the

The connection between this system of vessels and the lateral
bands is somewhat different. Several longitudinal vessels anasto-
mosing at intervals surround the lateral bands, and represent the
dorsal and ventral trunks in this region. These are connected
directly with the transverse vessels.

If the anterior extremity of the worm be removed about three-
quarters of an inch from the head and slit up with a fine pair of
scissors, by passing one of the blades through the pharynx; a pre-
paration may be made like that represented in Fig. 7, by carefully
removing the pharynx. The four sets of longitudinal vessels—which,
together with the transverse vessels and vesicles, I shall no longer
hesitate to call a water vascular system—will be seen to form a plexus
by anastomosing with each other, which entirely surrounds the
pharynx. This portion of the water vascular system is destitute,
or almost destitute, of vesicles. The plexus terminates anteriorly
in a well-marked ring. The ring gives off six branches which
open externally one on either side of each lip. This ring, and the
vessels given off from it in front, are figured by Dr. Bastian,* and
described by him as nerves and a nervous ring ; in this he has pro-
bably been misled by Schneider’st description, although Schneider
has clearly described a totally different structure.

The external openings on the lips (Fig. 4aa) are oval and
have a slightly raised margin. The external integument is con-
nected with the walls of the vessels at these points. Just within
the margin of each opening there appear to be several perforations,
generally two or three; but as far as I can make out they all open
into a single duct. These have been described as papill, and have
always been supposed to be sensory organs. J. H. Flogelft has
described and figured precisely similar structures on the lips of
three different species of Oxyuris, but speaks of them as papille
over the terminations of nerves. Dr. Bastian§ admits that he has
been unable to trace any nerves into the papillé of Ascaris.

With regard to the transverse ventral slit opening into the
water vascular system, which has been described again and again
in Nematoid worms, I can find no such opening in Ascaris; there
is but one transverse ventral slit, and that is the orifice of the female
sexual organs. I have found no such opening in the male.

The transverse opening described in some Nematoids seems, as
far as I can judge, to belong to some other system of organs.

If a portion of either the dorsal or ventral main trunk be care-
fully removed, with its transverse branches and vesicles, it will be
found that there are numerous secondary and tertiary vesicles.

* Dr. Bastian ‘‘On Nematoid Worms,” ‘ Phil. Trans.,’ vol. elvi., p. 54.

+ Schneider, ‘Monographie der Nematoiden,’ and ‘ Mull. Archiv,’ 1863, P. 1.
¢ ‘ KOll. Zeitschrift fiir Zoologie,” band xix., p. 234.

§ Loe, cit.

Pl. LXXVI,

Feb] 1871.

all
A

ana.

a The Monthty Microscopic al Jo

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Structure of the Round Worm.

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—

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4
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Royal Microscopical Society. 59

These differ from the primary vesicles in opening into each other,
and into the primary vesicles, just as the latter open into the trans-
verse vesicles.

These secondary and tertiary vesicles give off minute dichoto-
mously dividing vessels, which dip into the muscular layer, and
ramify in and over all the organs of the body, forming a true
pseudo-hemal system. The main trunks, lateral branches, and
vesicles of the water vascular system have an external coat of fine
muscular fibres, an inner membranous coat, and an epithelial lining.
The pseudo-hzmal vessels seem to consist of membrane only.

The whole water vascular system is filled with a viscid mole-
cular fluid, and is most conveniently seen by staining the tissues
with an alkaline solution of carmine, or by treating a portion of the
worm with dilute acetic acid. Specimens so treated and mounted
in glycerine jelly are exhibited under the microscopes.

I will recapitulate the main points, in order to avoid any chance
of being misinterpreted. The water vascular system consists,
according to my observations, of a ring round the pharynx, con-
nected with pores in the outer sides of the lips, and giving off a
plexus of vessels posteriorly. From this plexus two large trunks,
one dorsal and the other ventral, pass to the posterior extremity of
the body, and two lateral sets of smaller longitudinal vessels accom-
pany the lateral bands.

Both lateral, dorsal, and ventral vessels give off transverse vessels,
which form a plexus, and bear numerous vesicles. The vesicles
open into other, and these into other vesicles, the latter giving
off fine vessels, which I have called pseudo-hemal. The pseudo-
hzmal vessels ramify in and upon all the other tissues.

The similarity of the whole water vascular system of Ascaris to
the ambulacral system of the Echinodermata can hardly escape
notice. If the Ascaris possessed ambulacral processes in connection
with the vesicles above described, the two sets of organs would be
nearly identical.

The water vascular system of Ascaris seems also to afford a strong
indication that Professor Huxley’s hypothesis concerning the nature
of the so-called pseudo-hemal system of Echinoderms and Annelida
is correct, that they really belong to the same system of tubes with
the ambulacral and water vascular systems.

I further suspect very strongly that in Ascaris we see a transi-
tional form, in which the water vascular system is immediately con-
_ cerned with the function of nutrition, with a somewhat rudimentary
condition of the alimentary canal, seen in the absence of a muscular
coat beyond the pharynx, which is connected closely with the con-
dition of things met with in the anenterhelminths, or worms without
any intestinal canal, where, as in Tenia, the function of nutrition
undoubtedly devolves upon a system of tubes homologous with a

VOL. V. F

60 Transactions of the

water vascular system. The remarkably anomalous condition of
the alimentary canal of Mermis seems to stand between the condi-
tion seen in Ascaris, and that in Tenia, Echinorhynchus, &ce.

The lateral bands present histological elements precisely similar
to those described by Claparéde* in the ventral cord (Bauchstrang)
of the earth-worm, about the nervous nature of which there can, I
think, be no doubt whatever. These are accurately figured by
Schneider. +

Each lateral band is divided into two, longitudinally, by a well-
marked raphé of fibrous tissue, and a central canal may be seen on
either side of the raphé. This may be clearly observed in a trans-
verse section. The greater part of the band consists of fine fibrous
tissue, minute oil-globules, and small corpuscles, called by Claparéde,
in the earth-worm, connective tissue nuclei. Besides these, there
are numerous larger scattered ganglion corpuscles, just as there
are in the ventral cord of the earth-worm. I have distinctly
traced the connection between these and the nerve filaments. The
whole band is invested by a delicate layer of epithelium, exactly as
that of the earth-worm is.

In the earth-worm the ventral cord terminates in a ganglionic
ring round the pharynx;{ in Ascaris the lateral bands terminate
in a similar ganglionic ring.

The pharyngeal ring gives off a thick band of similar struc-
ture to each of the lips, which terminates in four large lobes.
Posteriorly the ring gives off several short tapering bands, identical
in structure with the lateral bands. These are soon lost in the
tissues. Occasionally one or both lateral bands split before joining
the ring. Nerves are given off at intervals from either side of the
lateral bands, which may be traced running transversely to the
muscular layer, and ramifying in the integument.

Schneider§ has clearly seen and described this nervous ring in
Ascaris megacephala, and has figured the lateral nerves given off
from the lateral bands; || but he has failed to trace the connection
between the lateral bands and the ring, and describes the nerves as
coming from a nerve-trunk in the interior of the lateral bands. I
suspect this has arisen from his method of treating his preparations
with acetic acid, and from the fact, that the longitudinal nerve-
fibres, which form chiefly the nerves, are situated in the centre of
each half of the lateral bands; whilst the commissural fibres and
ganglion cells are scattered over their periphery.

With regard to the nature of the axial canals in the lateral
bands, I confess I am ignorant. I have a strong suspicion that

* E. Claparede, ‘ Zeitschrift fiir Zoologie,’ band xix., p. 563.

+ ‘Monographie der Nematoiden.’ t Claparede, Joc, cit.
§ ‘Monographie der Nematoiden,’ and in ‘Mull. Archiv.” 1856. P, 1.
| ‘Monographie der Nematoiden.’

Royal Microscopical Socrety. 61

they are pseudo-heemal sinuses, from the large number of minute
pseudo-hemal vessels which appear to ramify from them. These
are very apparent when a transyerse section of the band is stained
with carmine fluid. The disposition of the parts of the bands are
represented in Figs. 4 and 5, Plate LXXYVI.

I have repeatedly observed certain oval cellular bodies, of
greater transparency than the bands themselves, at intervals bulging
out, and apparently compressing the normal structure of the bands.
They are very irregular in their occurrence, and I have been unable
to make out their import. They are very like the cellular bodies
which Meisner described as so abundant in the lateral bands of
Mermis. Meisner thought the lateral bands of Mermis were con-
nected with the alimentary canal, and called them corpora adiposa.
The connection between the alimentary canal of Ascaris and the
lateral bands is by connective tissue only, as has been already
stated ; and the same is even more marked in Gordius.* The spe-
cimens in which I observed the cellular bodies had been preserved
in spirit too long, but I have no doubt they are collections of
ganglion corpuscles, so that they may be looked upon as true
ganglia. The lateral bands contain a large quantity of oily matter,
and unless examined in a tolerably recent condition it is impossible
to make out their true nature.

Cuvier seems to have rightly interpreted the nature of the lateral
bands. Meisner has described certain nervous cords in Mermis,
but I suspect he fell into the same error as Cloquet and Otto, who
described the dorsal and ventral bands in Ascaris as nerve-trunks.
Perhaps Meisner has described a portion of the water vascular
system as a nerve-trunk ; I do not know, as I have not examined
Mermis; but I cannot help believing that the bands, or some of
them, for there are three, are homologous to those in Ascaris. In
-Gordius there is a single ventral cord, which undoubtedly represents
the lateral bands in Ascaris; in this I think I agree with Schneider.
It is on the ventral aspect of this cord in Gordius that Meisner de-
scribed his ventral nerve-cord, but Grenacherj} has failed to detect
it. The last-named author thinks that the ventral cord in Gordius
as well as the lateral bands in Ascaris are mere folds of the cellular
layer of the integument. In this I cannot agree with him; and
his beautiful drawings of Gordius, in the paper already referred to,
are far from giving me the idea, that the ventral cord is so simple a
structure as he is inclined to consider it. The epithelial layer
covering the lateral bands may, however, be a portion of the inner
layer of the integument, and this leads me to say a few words on a
point of very considerable interest.

* Dr. H. Grenacher, ‘Zur Anatomie der Gattung Gordius.’ ‘ Koll. Zeitschrift

fiir Zoologie, band xviii., p. 322.
+ Loc, cit.

p2

62 Transactions of the

I am beginning to suspect that the nervous system of the
invertebrata is developed, like that of the vertebrata, externally to
the serous layer of the blastodermic membrane. I expect soon
to be able to throw some light upon this subject; let it suffice at
present to say that it is possible that the cellular layer of the
integument of Nematoids may represent the serous layer of the
blastodermic membrane, and this is apparently folded so as to
invest the lateral bands. 'The ento-thoracic growths of the integu-
ment in insects point to the same conclusion. But this is mere
theory with our present knowledge.

From my observations I conclude that the nervous system in
the Scolecida is not formed on so variable a type as imperfect
observations have hitherto led us to believe; but that it is entirely
transitional between that of the Annelida and Echinodermata.

In the Echinodermata we find a ganglionic ring around the
pharynx giving off nervous cords in a radiate manner, the cords,
like those in Ascaris, being ganglionic. In Ascaris, if I am right,
we have a ganglionic ring giving off several short and two long
ganglionic nerve-bands. In the earth-worm, according to Claparéde,
we haye a single ventral nerve-cord connected with a ganglionic
ring. A step leads us to the condition seen in many Annelida—
a single ventral nerve-cord with ganglionic enlargements, and the
transition is easy to the whole series of Homogangliata.

If we compare the nervous system of Tetrastema, one of the
Nemertids, with that of Ascaris, as I have described it, we shall be
struck with their close similarity. In Tetrastema we have the
lateral disposition of the main nerve-trunks, as in Ascaris; but
they are no longer ganglionic bands. We have the cesophageal
Tings, but we have a pair of cephalic ganglionic enlargements
added.

From all that I have said it will be apparent that the Nematoid
worms stand in a clearly intermediate position between the Kchino-
dermata and Annelida. The water vascular system with its vesicles
remind one strongly of an Echinoderm; the pharynx, pharyn-
geal teeth, and segmented integument are clearly those of an Annelid,
whilst the nervous system is more nearly like that of the earth-
worm than that of an Echinoderm. In Gordius I think there can
be no doubt of this, where there is but a single ventral cord. I
cannot agree with Dr. Bastian’s view that the Nematoid worms are
more nearly allied to Echinoderms than to Scolecida, although I
must think much credit is due to him for having first pointed out
strong affinities with the Echinodermata,—not stronger affinities,
however, than those known to exist between Nemertids and
Echinoderms.

The transition from the form seen in Ascaris to that of the
anenterhelminths, especially Echinorhynchus, which has the lateral

2

Royal Microseopical Society. 63

bands of Ascaris, seems to me to be indicated in the want of
muscularity in the intestinal canal of Ascaris: and its remarkably
modified form in Mermis, where it is entirely deficient, except in
the anterior part of the body. Again, it is difficult to doubt the
affinity between the Nemertida and the Nematoida.

I have little to say further on the anatomy of Ascaris, the
reproductive organs have been so carefully described by Cloquet,
Dr. Cobbold, and others. I will only add to their descriptions that
the walls of the ovaries uteri and vagina, as well as of the testis and
its duct, have a distinct muscular coat, upon which nerves and
pseudo-hzemal vessels may be traced.

I have also a few facts to add concerning the development of the
sexual elements.

The ova in the upper part of the ovaries somewhat resemble
conical epithelial cells, and fill the whole ovarian tube, meeting
in its centre or axis. They are white and very granular, and
exhibit no distinct cell wall. I am doubtful about the nucleus,
but believe I have detected it in several instances. These conical
ova are more loosely packed in the lower six or eight inches of the
ovarian tube, and begin to-exhibit traces of division at their base.
Lower still they have formed distinct buds, which become detached
and form the yelks of the eggs. Meisner has observed a similar
process of multiplication of ova in Gordius, and in some Lamelli-
branchiata. In the larger part of the genital tract, the so-called
uteri, the ova become invested first in a strong yelk-capsule, and
later in a beautiful sculptured chorion. The ova are deposited in
strings, like those of Mermis, adhering by the chorions.

It has been stated that several months elapse, durmg which
period the ova need to be submerged in water, before development
proceeds in them to yelk segmentation; but I have specimens of
eges taken from a worm, which was placed in spirit as soon as it
was voided, which exhibit several distinct stages of yelk segmenta-
tion.

The male sexual element exists in the upper part of the tubular
testis in the form of minute distinctly nucleated caudate cells,
attached to each other in a manner precisely similar to the budding
ovarian cells; they do not exceed the sooth of an inch in their
long diameter. Lower down in the testis they are polygonal from
pressure, and have increased to +,5,th of an inch in diameter, still
with conspicuously bright nuclei.. The nuclei are replaced ina more
advanced part of the testis by bright nuclear particles, of which
there are from twenty to thirty in each cell. The remainder of
the male sexual canal, which is very capacious in proportion to the
testis, was entirely filled with similar cells, so that I am ignorant
of any further changes which they may undergo.

The development of the ova as far as it is at present known has

64 Transactions of the Royal Microscopical Society.

been described by Dr. Cobbold, I have, therefore, no more to add
upon this head.

This concludes what I have to say on the structure of Ascaris.
I have endeavoured as far as possible to avoid errors, and trust I
have done somewhat to put the anatomy of the Scolecida on a more
secure footing than it has hitherto possessed.

DESCRIPTION OF PLATES.
PLATE LXXYV.
Details of the Anatomy of Ascaris lumbricoides, §c.

Fic. 3.—A fibre of muscle from the body wall x 120.

» 4.—The mouth seen in front. a, a, openings of water vessels x 30.

5» 0.—The pharynx laid open, showing the ridges in the interior, x 10.

» 6.—Anterior extremity of one of the pharyngeal ridges x 40.

» 7.—Anterior extremity of the worm laid open, showing, 5,5, the water
vascular, and d,d, the nervous bands, with their ramifications and
connections, x 15.

;, 8.—The external opening of one of the water vessels x 120.

5 9.—One of the lips x 30.

», 10.—Cells from the upper portion of the testis x 750.

55 11.—Cells from the middle portion of the testis x 500.

5, 12.—Cells from the duct of the testis x 500.

PuaTE LXXVI.
Details of Anatomy of Ascaris lumbricoides,

Fic. 1—Half a transverse section, made about two inches from the head, x 20,
showing, a, external layer of integument; 4, cellular layer; c,
muscular layer; d, lateral nerve-band; e, transverse water-vessels
bearing vesicles (appendices nouriciéres); f, alimentary canal; g,
dorsal water vascular trunk x 20.

» 2-—A portion of the dorsal trunk, with transverse vessels, vesicles, and
pseudo-hzmal vessels, detached from the other structures, x 25.

» oA Adapts of the testis, with pseudo-hemal vessels ramifying upon
it, x 60.

» 4.—A transverse section of one of the lateral bands x 40.

5 0.—A portion of one of the lateral bands, x 25.

» 6—Ganglion corpuscles from the same x 500.

» 7-—A budding yelk from the lower part of the ovary x 200.

5, &—Three yelks from the upper part of the ovary x 200.

» 9.—A budding yelk, from the lower extremity of the ovary, dividing into
two, x 200.

Immersion Lenses and New Refractometers. 65

V.—On the History, Refractions, Definition, and Powers of
Immersion Lenses and New Refractometers. By Royston-
Pigott, M.A., M.D. Cantab., M.R.C.P., Fellow of the Cam-
bridge Philosophical and the Royal Astronomical and Micro-
scopical Societies of London, formerly Fellow of St. Peter’s
College, Cambridge.

(Part I.)

I.—History has handed down to us the labours of CLauprus
Protemy, the Father of Optics. His celebrated experiment of ren-
dering a coin visible placed in an empty vessel by filling it with
water, was perhaps the first scientific attempt at experimental
refraction : thence he proceeded to measure the refraction of light
passing from water into air, from air into glass, and lastly from
water into glass. He sagaciously avoided the deviation from glass
into air by taking care the rays should emerge perpendicularly to
the surface of the glass.

Bent Oar in Water. Refraction from Air into Water.

His very ingenious mode of settling these points, as it really
involves the important principle of the MODERN IMMERSION LENS,
may not be uninteresting to those unacquainted with the experi-
ments. Observing the crooked image of an oar in water, and the
curious apparent rising of the money as the water is poured into the
vessel, he had a semi-cylinder of “pure glass” constructed, to which
he adjusted a graduated circle, so that the diameter of the cylinder
coincided precisely with the diameter of the graduated circle above
mentioned, and also with the surface of the water. A small
coloured body was placed at the centre of the circle; a second
similarly fitted to one of the quadrants out of the water; a third
slided on the lower part of the graduated circle immersed in the
water. Observations were then made upon the angles of incidence
and refraction of such a degree of accuracy as to excite our admira-
tion after a lapse of nearly two thousand years. The determination
of the conditions of refraction through A WATER LENS was thus
anciently effected sufficiently exact for all the practical purposes of
modern theory.

66 Immersion Lenses and New Refractometers.

Ptolemy observed that the refractions from water into glass
were less,than any he had previously observed. The following were
some of the results he obtamed :—

Ciavupius Protemy’s TABLES.

} |
REFRACTIONS FROM GLASS INTO AIR. REFRACTIONS FROM WATER INTO GLASs.!
|—

| Angle of Incidence. | Angles of Refraction. || Angle of Incidence. |Angles of Refraction.

° ° i ° te} ‘
| 0 Om0 0 Oneal
20 13 30 20 18 30
| 60 34 30 60 49 30
80 42 0 80 62 0

The first Table on the left, for the 4 angles, gives the value of
the refractive index for Ptolemy's “pure glass” at 1°48, 1°53,
1:47; the mean of which is 1°49, or nearly the refractive index
for our common glass, and evidences the singular care Ptolemy must
have taken in his experiments.

For the water refractions the values of the index of refraction
between glass and water are (by the refractometer, to save the cal-
culation by logarithms), for 60’ and 80° in the Table, nearly 1-500
and 1°336, a surprising approximation to the true values by this
primitive method.

ProLemy’s Immersion LENS.

Refraction from Water into Glass.

If the glass cylinder be removed, then the ray would be turned
back by the surface of the water, and internally reflected, instead
of being refracted.

Immersion Lenses and New Refractometers. 67

This valuable experiment of Ptolemy I particularly beg to recom-
mend to those opponents of immersion lenses who deny that by their
means a much greater amount of rays radiating from a Canada-
balsam mounted object ultimately reaches the eye of the observer
than can possibly be effected by aérial or dry refraction in the
ordinary way.*

In order to show the agreement between Ptolemy’s Tables and
those given in the papers by the writer “ On the Optical Advan-
tages of Immersion Lenses,” it will be convenient to the reader to
reproduce here the final Table of results from page 140, September
Number, 1870.

TABLE V.
Ratio of
J Quantity of | Angle of Total
REFEACTIONS. |Nascent Pencils Aperbate. Reflexion.
Transmitted.
5 | ° ‘
Plate glass to air .. I | 83 36 | 41 48
is water .. 21 125 54 62 57
Flint glass to turpentine 31 | 156 46 | eo
Refractions from Cover through Quantity of Necessary Objective | Limiting Angle
Refracting Film. Defining Pencils.) Aperture. of Transmission.
|

Tracing the history of immersion lenses, we may relate that Sir
David Brewster employed lenses recently extracted from fish and
other animals, as well as minute drops of castor oil, &c., formed
into plano-convex lenses, and even a mixture of fluids of different
dispersive and refractive powers, and indeed glass lenses immersed
in fluids. This was about 1812.

In 1855 Professor Amici showed, at the Paris Exposition, a
microscope acting upon the immersion principle, which “ exhibited
certain strixt better than any of the instruments under examina-
tion” by the jurors in Class VIII. This superiority was produced
by the introduction of water between the object and the object-glass ;
but as Professor Amici could not be considered as an exhibitor, the
jury was not called upon to adjudicate to him a medal.t

“The employment of fluids of various dispersive powers, says the

* See Mr. Wenham’s Paper, Jan., 1871.

+ The Amician Test for many years held a first rank as a test for the 3,th.

t “Mr. Andrew Ross intended to exhibit in Paris object-glasses of a still
higher order than those we have mentioned, and would thus have found
himself in competition with his eminent rivals, Messrs. Smith and Beck, and
M. Nachet. He was prevented, however, by the pressure of business from
exhibiting the new object-glass, and Messrs. Smith and Beck, who had no
English rival, carried off the microscopic prize, by receiving a medal of the first
class. Although the microscope of M. Nachet was not equal to that of the
English artists, it had such a high degree of merit, that a medal of the same
value was adjudged to him.”—‘ Ency. Brit.,’ art. “ Microscope.”

68 Immersion Lenses and New Refractometers.

writer in the ‘ Ency. Brit.,’ gives the artist a wider range in his
experimental researches.” M. Achille Brachet, of Paris, has added,
in Italian, M. Amici’s own account of his invention.

“These glasses were constructed on a new principle—that of
immersion in water—and the most extraordinary point of the dis-
covery was the very considerable distance preserved between the
objective and the object under view.”

“The series No. ITI. and No. VI. on this new principle renders
the image more clear and distinct, and does not require any correc-
tion of the error which the common system introduces, owing to
the different thickness of the covering glass. This advantage was
obtained by immersing in a drop of distilled water the last lower
surface of the series III. and VI.”

TABLE OF AMICIAN ELEMENTS.

| No. IU1., Immersion. No. VI., Immersion.
Thickness of covering glass .. | anor 70397 0-010”
Inches, focal length oetAiee || sO" d Be ort 0°0685 or 3, nearly
PATELEUTE MG cath cal ten || 70° 160°
Power, diameters .. .. .. | 535 1310

“ Professor Amici is of opinion that no object-glass hitherto
constructed has a power as great as his Series No. VI., and con-
sidering the distance (about 0™™"-4, or 16 thousandths of an inch) *
which is left between the object-glass and the object, with a large
aperture of 160°, he thinks he has given proof of the superiority of
the principle he has invented.” (q'; usually requires a “cover ”
only 4 thousandths thick 0°004".) ‘ Professor Amici tells us that
his object-glass No. III. is composed of five, and No. VI. with se
different refractive and dispersive substances.” T

The English, with their stolid resistance to change and new ideas,
had persisted, up to a very recent date, in ignoring the immersion
principle. Indeed, none of our opticians have taken them up till
compelled by the pressure of public opinion and ardent amateurs.
The splendid abilities of Professor Amici, aided by his optical
knowledge, perhaps surpassed herein even ANDREW Ross, who had
a lifetime to learn the Microscopic Art. There are even now, I
believe, no dry objectives made of the ,!,th of an inch focus, capa-
ble of viewing an object through a glass cover one-hundredth of an
inch thick without adventitious aid.

Such, then, being the history of the immersion lens, our Con-
tinental friends, who crowded to Paris in 1855, became thoroughly
acquainted with the superiority of the immersion principle, and

* A simple method of converting millimetres into inches, sufficiently near,

is to multiply the mm by 4 and divide by 100, or cut off two ciphers.
+ ‘Ency. Brit.,’ p. 783, Ed. 1857, art. “ Microscope.”

Immersion Lenses and New Refractometers. 69

have, accordingly, for many years been using them; whilst the
English have been struggling with the formidable difficulties of
correcting the glasses for aérial refractions ; the film of air making
enormous differences in the course of the excentrical pencils.*

For whether we trace the rays downwards through a microscope
to the object, or upwards from the object, no possible difference is
made in the course of the ray so long as the conditions of the
media remain the same.

A ray radiating from an illuminated particle immersed in the
balsam and striking against the surface of the air above the cover,
is totally reflected at an angle of about 42°; but substituting
water for air at about 62°, as follows from Ptolemy’s discoveries.

To use the words of one of the most distinguished writers on
Optics in this country, to whom the writer submitted the prin-
ciple of the water lens, advocated in these papers, a much greater
number of rays from the object reaches the eye of the observer
vid water, than can possibly take place vid air.

But not only do more than double the quantity of rays reach
the eye through the objective and eye-piece, but they find their
way more directly without such violent bending or abrupt refraction.
This advantage is inestimable. For, as is well known, the aberra-
tion of a prism is a minimum only when the deviation is the least
possible, and all lenses act on the principle of the prism.

The celebrated Huyghens invented his eye-piece entirely upon
the principle of dividing the refractions as nearly as possible, so that
each lens should bend the rays equally at a minimum deviation.
Fortunately, and unexpectedly, the combination of the focal lengths
of the lenses as 3:1, and separating the lenses by a distance equal
to half their sum, also produced an excellent achromatism for
parallel rays as it were by accident.

Messrs. Powell and Lealand have informed me that in using the
greatest obliquity of illumination attainable by their peculiarly-

* As it seems right in the eyes of some of the old lovers of dry objectives to
dispute a number of things which they did not learn in their youth, it may not
be out of place here to quote a principle, at which, doubtless, advanced optical
students are quite aw fait. The aberration of the direct ray refracted through a
plate ‘“ of thickness (¢), is equal to the thickness multiplied by unity divided by
the refractive index.

t 1
mee z and - = sine of angle of total reflexion. (See p. 72.)

a5
. For plate glass, it is therefore 2 the thickness: for a film of water it is TT the

thickness. But the dispersion is very different in the two cases: for oblique
rays the aberrations for obliquity @ are respectively for thickness (¢ = 1)

2 3
3 secant @ and q Bee. 8,

and enormous differences in the paths of the excentrical rays necessarily result.”
(See Parkrnson’s ‘ Optics,’ p. 79.)

70 Immersion Lenses and New Refractometers.

mounted condenser, it was only when the immersion lens was used
that the extremely oblique light from the object could enter the
object-glass and pass to the eye ; the object being mounted of course
in Canada balsam. If, indeed, we plunge the objective into Canada
balsam, to view an object immersed in it (as proposed by Mr. Wen-
ham, page 18, line 7), in order to demonstrate the principle of the
water lens by applying it without the water to prove its action
with it (save the mark !), though they have very different refractive
effects—why we can thus certainly imagine both effects are alike.*

It cannot be too clearly asserted that no dry objective, whatever
be its aérial aperture, can receive within the substance of its front
lens rays more oblique that 42°, nor with an immersion film of
water more oblique than 62°. And, even then, the ray in both
cases must strike the face-glass at an obliquity of nearly 90°. Yet
Mr. Wenham says they are both alike! It would be unkind to
suggest that Ptolemy’s optics, nearly 2000 years old, have an
advantage, as regards immersion lenses, over Mr. Wenham’s. I
commend the Ptolemy immersion lens to his especial cogitation.

II. Refractions.—In so interesting a question, the teachings of
Nature herself should not be neglected. “ The crystalline lens” is
an “immersion ” placed in two refracting fluids, possessing an aper-
ture of above 100°. In fishes, the view under water is worth con-
sideration. ‘To the gaze of the fish the whole prospect of earth and
sky is contracted within a cone of which the apex is the eye and
the base a circle of about 96° angular aperture, beyond which
many objects, as its fellow fish, appear double by total internal
reflexion.t The angler on the bank of the river is seen in minia-
ture. As objects approach the zenith, they enlarge rapidly. All
the objects on the horizontal plane are crowded into a minute
annular space.

If we hold a tumbler of water steadily above the level of the eye,
any substance floating in the water may be seen internally reflected
at the upper surface more brilliantly than any metallic surface can
effect it, by reason of the total internal reflexion (Parkinson). This
phenomenon beautifully explains the great loss of pencils radiant

* It is hardly necessary to inform the reader that the Plate LX. is drawn
merely to illustrate the comparative angles of total internal reflexion in the case
water versus air lenses, as also the deviations and aberrations of the rays upon
entering the first glass front of the objective. Indeed, the curves of the upper
lenses are quite unnecessary for my purpose; and the extremely minute scale of
the refractions at the focus, when sufliciently enlarged, left no room in the plate
to draw the lenses correctly. Mr. Wenham very properly points this out in his
stricture on page 17, January, 1871. But this does not in the least affect the
question of comparative refractions between the brilliant particle and the first
surface of the objective: the real point at issue, in the case of dry and immersive
Baar aquariums (now destroyed) exhibited very brightly the images of the

gold and silver fish totally reflected by the upper surface of the water to the
visitors at the Crystal Palace, who looked upwards through the side.

Immersion Lenses and New Refractometers. 71

from the object, necessarily effected by the use of dry objectives with
a Canada-balsam mounted object.

I believe that in this country the first notice of immersion lenses
was by Mr. Mayall, jun., in a paper, Feb., 1868. Comparing the
two methods, he says:—“The relative separating and defining
power of the two systems have not received that attention which it
deserves.”

Mr. Mayall continues :—“It is not difficult to see that Amici’s
system of connecting the objective with the cover-glass by a film of
water very much diminishes the reflexion which necessarily takes
place in the incidence of the oblique light when the dry objective
is employed. The limiting angle of refraction in water being about
48 degrees (sic), it follows that whatever is the degree of obliquity
in the incident light on the object, the immersion objective never
has to do with rays of greater obliquity than 48°. To this, m
ereat measure, is due the greater clearness and precision of image
obtained. Continental opticians and men of science have been
aware of the merits of the immersion system during several years
past ; and to such purpose, that knowing how little attention it has
received, here, they do not scruple to say that the English no longer
take the lead either as opticians or as microscopists.”

This glaring error of 48° most probably arose from the writer
taking the angle of total internal reflexion between water and air
instead of water and glass.

In the ‘ Popular Science Review’ (p. 330, 1868), the talented
Editor remarks :—“ Hartnack’s immersion lenses appear to be get-
ting into general use for work which does not require such high
powers as the 34th to =';th objectives; but the subject of immersion
lenses requires to be more fully worked out than it has been. We
want experience of those who have employed both forms of object-
pene and who can fairly and fully state the respective qualities of
each.”

In the ‘Monthly Microscopical Journal,’ Dr. Lawson observes
(p. 217, vol. ii.) -—

“Mr. Ross’s New Immersion Lenses.—Mr. Ross has just pre-
pared a number of immersion lenses, which our readers will do
well to examine. There is a decided improvement over the dry
glass in definition, and there is vastly more light.”

A recent writer in this Journal (Mr. Wenham) seems to follow
in the wake of Mr. Mayall, for he states (p. 17, XXYV.) :—‘ The
same optical law that limits the aperture of any object-glass to
near 82° in a balsam-mounted object also determines the angle in
the lens at which the rays diverge after being refracted from the
plane surface of the front. This can never exceed 82° in a dry
objective, nor can it be greater on theimmersion system.” Verbum sat.

72 Immersion Lenses and New Refractometers.

It would seem that these writers must be unacquainted with
the standard works on Optics, and so of course should not be ex-
pected to know that the angle of total internal reflexion or “critical
angle,” as it is called, is dependent upon the refractive indices of
both media through which the incident ray is passing. Thus Dr.
Parkinson, F.R.S., in his edition of Rey. W. Griffin’s ‘ Optics’ :—

“ Definition. — The angle whose sine is Ls which the angle of

incidence in the denser medium must not pa in order that
refraction into a rarer medium may be possible, is called the critical
angle of the media between which the refractive index is p.”

To find the mutual index of refraction between glass and water,

( shorter is PY) Dr. Parkinson gives the following
example (p. 76, ‘ Optics’) :— ,

glass water

: 4
“ Ex.—From air into glass w= 2. from air to water p= 3° Hence from

glass to water (denser to rarer medium)

a index from air to water _ 8 ad (= 4 $.: 3 )
G Ww index from air toglass 9 \ 3° 2

in other words, the index of refraction for rays passing from water

into glass is =, and the critical angle is that whose sine is 1 + 8

or 4 , 2.€. 62° 44'* This nearly agrees with Ptolemy’s 62°.

The distinction between the critical angles when air is not one
of the refracting media is not given in general in popular works on
Optics, although so well described by Protemy.

Professor Haughton writes (p. 28, ‘ Optics’):—“The total

* Ptolemy’s value is 62°. Taking these values we have from the ordinary

tables, since 2 = 0°88889 nearly,
log. 0°88889 = 1°94885 = log. sin. 62° 44’, or 62° 44’ instead of 62°.

8
The rough approximation 9 gives nearly the same result as the decimal values
of u in the two cases, viz. 1°500 and 1°336, usually employed when the value
becomes 62° 57’.

Again, for 80° the sine of angle of refraction = > sin, 80°

x 0°9848078 = 0°8753847 = sin. 61°°5’

The refractive index of the glass used by Ptolemy, since that for water is known,
was nearly that of plate or crown glass: as will be found by the formula

sin.
f= gt o”

a
es

Immersion Lenses and New Refractometers. 73

reflexion of light may also be illustrated by means of the following
apparatus :—

“ A glass chimney is fastened into the bottom of a rectangular
vessel of glass, abed, which is filled with water, and a candle
introduced into the chimney. The rays from the candle are seen
to emerge from the water when the angle of incidence is less than

the angle whose sine is ide but when the incidence exceeds this
limit, the light is seen to be totally reflected, and none passes

through the surface of the water.” The angle whose sine is mn

of course equals 48° 35’ nearly. Now will the reader suppose that
a layer of oil of cassia is poured upon the surface of the water, then

mats for cassia, » the refractive index is 1°635

for water, 5s ye 1°336

for the line E (of the spectrum of Fraunhofer) of mean refran-
gibility. Evidently it is quite impossible that the angle of total
internal reflexion can be the same as before, when the ray, emerging
from the water, strikes the under-surface of the cassia.

The value of = is now 1°336 — 1-635 = -8171.

The angle whose sine is 2 = 54° 48’, which is a great increase

on 48° 35’. For water and glass it is, as we have seen, about 62°.

The most important part of the subject is unquestionably —

Ill. Definition—The writer cannot but regret that he has had
the misfortune to incur the displeasure of Mr. Wenham in making
the following statements in the interest of Microscopical Science :—

“ Even in a good 3th object-glass the spherical aberration does
not exceed the 50,000th of an inch.”

“ The most difficult definition in the Podura is the substratum
of beads glimmering through the membrane nearest the light. . . .
The beading dispels the mist and haze always accompanying the
spurious ‘ spines. ”

“That our old-fashioned glasses are wrong somewhere—in the
correction of spherical aberration.”

“That the battle of the glasses will have to be fought; and
that the superiority of the immersion lens is an irrefragable proof
_ of the corrections necessary.” (Dec., 1869.)

“That in viewing the image of a flame in a minute globule the
spurious disk is more than double the size of the true size of a
perfect aplanatic image.”

“That in the diameter of this spurious disk lies the whole pith
of the objective corrections.” (Dec., 1870.)

74 Immersion Lenses and New Refractometers.

That the writer of the present article has described several
appearances which Mr. Wenham has never yet acknowledged to
have been able to see, who therefore denounces them as spurious !

It was then pointed out that double stars could be imaged to
any degree of minuteness even 100,000th of an inch apart, upon a
minute mercurial globule, in reply to Mr. Wenham’s challenge.

Whereupon he roundly declares (January No., 1871) :—

“T must protest agaist the positive manner in which Dr.
Pigott still totally condemns the mercury globule. ‘This self-
confidence may be attributed to non-acquaintance with it.”

: Next, speaking of my double-star image test, he rather oddly
admits :—

“That the separation of two points of light on the globule
coming from two sources placed at a given interval is a test no
one will question.”

I am exceedingly glad to hear this. I was really afraid Mr.
Wenham would annihilate this eaperimentum ecrucis after the
solemn protest aforesaid. But Mr. W. is more generous still. He
srants me the whole pith of the question in one full admission,
which saves the writer from all further anxiety about Mr. W.’s
opinion. He magnanimously asserts :—

“The greatest value of its indications are when it (the globule)
is considerably within or without the focus. . . . That it is em-
ployed solely for the purpose of obtaining a distinct image is quite
a mistake. . . . No optician thinks of the possibility of a distinct .
image.”

If the reader will turn to page 265, November Journal, 1870,
he will find a statement of mine to the following effect :—

“The image of a flame reflected by the test globule is a round
disk, much larger than it ought to be, as seen in all isolated brilliant
points in the microscopical field. It is interesting to inquire at
what size its image can be discovered.” (The reply is never !)
“ And if such small globules are employed that the shape is gone,
and if the real diameter of the spurious disk is a test of the correc-
tion of the glasses, what becomes of the boasted accuracy of the
globule test, in which the size of the spurious disk is totally
neglected ? No one ever thinks, in testing microscopes, at all
about this spurious appearance. In telescopic testing, the most
essential part of the ordeal is the diameter of the spurious disk.”

Mr. W. now declares that the globule test is used principally
for correcting the combinations of the lenses in detail, beginning
with the back set first, in which excessive aberrations are purposely
introduced, and therefore not “ to correct the least fault.”

So that its employment to test the real focal point and the size
of the spurious disk is, after all, exactly what has been stated. The
fact is, for the deep objectives, anything but a wild attempt to get a

Inmersion Lenses and New Refractometers. 75

mercurial image from the globule placed immediately under deep
objectives 2s dmposszble.

I cannot properly conclude this article without some allusion to
the edifying and philosophical personalities which grace Mr. W.’s
papers. I can only ask the readers of this Journal to decide
whether he has forteited the pledge he gave to carry on the con-
troversy “in a fair spirit, being willing to receive or give an
information that may tend to elucidate truth” (p. 301, June, 1870).
[The “information” would surely have been quite as valuable
without the ornate argumentum ad hominem so liberally employed. |
His chief reason for commencing the controversy being, as he states
in the same page, “the slur that-is cast upon the object-glasses of
our best makers by the assertion, that in the best glasses there is a
residuary aberration which obscures the clear definition under a power
of 1000.” It is fair to compare this with the new admission.
Speaking of my double-star test, he says (January, 1871, p. 22),
“A bad glass will blur them together, and a good one will separate
them more or less distinctly.” Do any of the old-fashioned glasses
or Mr. Wenham’s best objectives blur them ?

“As no optician thinks of the possibility of a distinct image’
whilst using the mercurial globule at present, I entertain a lively
hope that the time is not far distant when they will use the amage
tests such as I have elsewhere described, as an exquisite means of
detecting unsuspected residuary errors. Mr. Wenham, however,
seemed at one time well aware of the many difficulties attending
the construction of object-glasses, as the following passage fully
demonstrates :—

“T am of opinion the case is different with a microscope object-
glass, wherein, with the highest powers, every trifling error is
enormously magnified” (p. 228, V.).

On the other hand he declares, “ the effect of the water and
covering glass is precisely the same in its corrective action as
additional thickness thrown on the front lens!!!” The same very
singular idea runs through the last effusion of Mr. Wenham.

It is, however, tolerably well known among physicists that the
effects of irrationality on chromatic dispersion vary very consider-
ably according as glass or water is the refracting medium,* and the
thicknesses under use.

I feel quite certain that the best makers of English immersion
lenses will hardly endorse either this adventurous statement, or
another, to the effect that “from an 4th upwards perfect correction
can be obtained from a single front.”

I am greatly impressed with the admission that the chief use of
the globule star is to examine the intended errors of the parts, and
not the requisite performance of the complete objective.

oe * See art. “ Light,” ‘Ency. Met.’
VOL. V. G

?

76 Immersion Lenses and New Refractometers.

I have submitted the very finest immersion objectives now
known to the image test, and, as might reasonably be supposed
with all human workmanship, I find the residuary error small, but
still appreciable. The greater the angular aperture, the greater
rises the almost insurmountable difficulty of compelling the oblique
pencils to converge to exactly the same focal point as the more
central rays (within a ring much less than the 50,000th of an inch).
Still, the best glasses are a marvel of skill, worthy of the science of
the nineteenth century: the least circle of aberration being so ex-
ceedingly small. No first-rate optician claims absolute perfection.

I think it right to add to this paper that I possess an inch
objective which displays the beading of the Macrotoma podwra, and
which I had the honour of exhibiting to Dr. Lawson on the 14th
instant (with about 600 diameters)—in order to avoid imaginative
effects—before he had seen them with the half-inch of Wray, and
the ith, and ;},th immersion of Powell and Lealand.

I am unwilling to retire from this controversy without recording
an example of Mr. Wenham’s “ fair spirit”—or rather spirited—
attacks upon these papers (and highly suggestive) :—

“ Our thanks are due to Dr. Pigott for his laudable attempts to
advance the microscope object-glass; but as he appears to stand
forward as the pioneer of a new era in their construction, ignoring
all glasses made before the publication of his first essay as ‘ old-
fashioned,’ such dictatorship naturally challenges inquiry as to the
merits of his investigations, and whether they have in any way con-
tributed to the end in view ” (p. 16, 1871).

Whether object-glasses are perfect, as Mr. Wenham guarantees
them,—whether any error can be detected, and whether the glasses of
1871 are finer than they were in 1869, I leave to the decision of com-
petent adjudicators, free from prejudice, and free from compromised
opinions. If my declaration of the detection of the 50,000th of an
inch aberration in the best glasses is thought so prodigious, 1 must
exercise greater circumspection so as not to offend susceptibilities
as unwonted in delicacy as conspicuous in refinement. I now
consider the controversy has extended long enough to tire the
patience of our Fellows, whilst the tone adopted creates an impera-
tive necessity for bidding it adieu in pages devoted to the ‘'Trans-
actions of the Royal Microscopical Society.’

As there is an emulation of no common kind between American
and English microscopists, the following passage from the ‘ American
Cyclopedia,’ vol. xi., “ Microscope,” 1861, is not without interest.
The article claims superiority for American glasses. Speaking of
the Amphipleura pellucida, 130,000 lines to the inch, it says :—

“Mr. Sollitt and Mr. Lobb both claim to have resolved it from

Immersion Lenses and New Refractometers. 17

experiments made with the Nobert test-plate, and from the most
careful examination with the best English and American objectives,
the most experienced American microscopists believe there is some
mistake.” This object has been so frequently seen in this country
that English microscopists would be glad to hear whether our Ame-
rican friends still disbelieve in its resolution, as this fact would be
a strong argument against this supposed “ American superiority.”

It isa highly curious psychological phenomenon, that whenever
some new advanced microscopical facts are discovered, old-fashioned
observers honestly believe their advocates to be the victims of
delusion, spurious appearances, ghosts, or mistakes.

IV. Description of two Refractometers,—the one Mechanical,
the other Logarithnuie.

Experiencing the tedious work of constructing tables of de-
viation for rays of light passing through successive media of known
refractive power, it ‘occurred to me that an instrument could be
contrived which should mechanically give the angles of refraction
for any angle of incidence between any known media.

Let a triangle be constructed none of whose angles are greater
than 90°, it is well known that the sides are in the exact proportion
of the sines of the opposite angles. Thus if A BC be the triangle,
a, b, c, the sides in inches,

a@:6 2: sin. A : sini B.

Now, suppose that a, b, represent the refractive indices of two

substances, then the sines of the angles of refraction and incidence

areasaand b. From this it follows, that if a triangle be con-
structed whose sides represent the refractive indices of two given
G 2

78 Immersion Lenses and New Refractometers.

substances, the angles between those sides and the base exactly
represent the angles of refraction and incidence between the two
substances. The diagram represents the angles (¢ and ¢’) of inci-
dence and refraction, when » =1°500; and for air, » = 1°00
nearly. When the angle ¢ at A becomes 90°, the angle B or ¢’
represents the angle of total internal reflexion 42° 48’, and so for
any other example.

The logarithmic refractometer consists of a slide rule, the upper
lines of which represent the refractive indices ; and the lower lines
and divisions give any angles from 90° down to 30’.

The angles of total internal reflexion are given at sight oppo-
site 90° by merely setting the refractive indices of the two media
proposed opposite to each other.

Further examples.—Find the angles of total internal reflexion
for the following substances, the ray passing into them from air,
refractive index taken = 1-000.

The refractive index is placed on B under 1:000, on A under
90°. The answers must then be interpreted.

Substance. Tabasheer. Oil of Turpentine. Canada Balsam. Spinelle. Blende.
Refractiveindex... 2-111 .. 2°478 .. 13549 So 7G -2G0
Answers ba) ws AGRO oa. AQRON Oe 40°. wis, | BAC eee eG

Find the aberration into air of a “ plate” of each of these sub-

stances as given in the note, page 69, ¢ x = Let ue
bh

Sines | sin. eae. «403°, 40° eee

Values | 0°90 -.. 0-675 .. 0°643. 2a EBER enn a4

From which it appears that the lower is the refractive index of a
film or cover, the greater effect has the thickness of it upon the
primary aberration nto ar of the pencil radiating from the illu-
minated particle under view ; another reason for preferring the water
film.

The above example is simply worked by placing 10 B or 90°
over the angle whose sine is desired, and reading off the numbers

under 1 on A: as 1 +p =sine of the angle of total reflexion in
each case.

On Microscopical Appliances. cS,

On the lines A, B, innumerable questions of refraction and
internal reflexion are answered on inspection.

It gives at sight also in most cases to three places of decimals
the sines of angles, thus :—

Sin. 214° = °365.* Sin. 10° 20’ = 0-179. Sin. 5° 5’ = 0°0885.

Again, if a ray of light passes from water into diamond, water
p. = 1-336 diamond » = 2°47, by placing these indices over each
other, at sight we see the following angles :—

Incidence 9° TO LST M rel 2OLO Mins, ) “BSo a hase yO DTCL a a OOe
Retractionw4ohomm ci LOc wes) IAC iie) D0Sn Mice a On sien 3O

The last, 33°, being the angle of total internal reflexion, and
subtracting one from the other, the deviations at given angles of
incidence are at once shown on the rule. The rule thus shows
these quantities :—

A | (Water) 1-336 |
B (Diamond) 2°47
go 188° 262° 38° «57g Giner
| 4°53’ 10° 14° 20° 97° ~~ 39° | SHAS

VI.—On Microscopical Appliances. By Dr. Royston-Piaorr.
No. I.
On a Useful Form of Dynameter Micrometer—the Kratometer.

Ir some time since occurred to the writer, that an instrument could
be so contrived in the form of an eye-piece which should serve some
very useful purposes of measurement, such as, (without the constant
use of the rule of three)

(1) To give, at sight, the magnifying power of any objective
for any length of tube in use at the time of observation.

(2) To ascertain the standard focal length of object-glasses of
all kinds, whether conventional or solar (for parallel rays).

(8) To ascertain the focal length of any given single lens re-
quired to be tested.

(4) To deduce the actual focal length of eye-pieces.
* (5) To measure objects in the field of view under any power or
length of tube.

(1) In the present number of the Journal I shall only embrace
the opportunity of describing the mode of fitting up the instrument,

* The rule is made by Cary, 181, Strand.

80 On Microscopical Appliances.

and ascertaining magnifying power. It is a negative eye-picce,
the lenses of which are so arranged as to magnify just five
times under the condition of the eye-lens magnifying ten times.
Within the focus of the eye-lens is placed a circular micrometer
scale ruled to 545th of an inch. Upon placing another micrometer
ruled to ;5ths and y;';5ths upon the stage, it“is plain the divisions
of the latter are exactly five times smaller than of the former.
Hence, since the eye-piece magnifies the image to the eye five
times, it follows that whatever power be applied by means of the
objective and length of tube, the actual reading of the stage
rosoth by the eye-piece will give the actual magnifying power
under use. ‘This method was employed as well as the camera
lucida in estimating the magnifying advantages gained by the
Searchers alluded to in the December article. The extreme simpli-
city of the instrument is its greatest recommendation; although its
modus operandi is not so very clear at first sight: but perhaps
the following statement may be of use towards its explanation.

If, for instance, we view a thousandth on the stage with a “ quar-
ter,” and the Kratometer eye-piece, we shall see, without using the
draw-tube, that a thousandth is covered (say) by 35:5 divisions of
the eye-piece ; therefore

Power of “ Quarter” = 355 = P.
If we draw out the tube several inches we may see that
P = 520.

Coe}

NEW BOOKS, WITH SHORT NOTICES.

We greatly regret that owing to the pressure of articles on our
space we are compelled to allow to stand over notices of the following
works :—

‘A Report on the Microscopic Objects found in Cholera Investi-
gations. By T. R. Lewis. Calcutta.

‘The Natural History of the British Diatomacea.’ By A. Scott
Donkin, M.D. London: Van Voorst.

And ‘Microscopic Objects Figured and Described.’ By J. H.
Martin. London: Van Voorst.

PROGRESS OF MICROSCOPICAL SCIENCE.

The Abdominal Antenne of Insects are Sense Organs.—The ‘ Ame-
rican Naturalist’ for December publishes a note on the above subject,
by Mr. A. 8S. Packard, jun., which is of considerable interest. Refer-
ring to Dr. Anton Dohrn’s note on the subject in the ‘Journal of the
Entomological Society of Stettin, 1869,’ he points out that he gave
notice of the above structures as early as 1866, in the ‘ Proceedings
of the Boston Society of Natural History.’ He says:—I have been
able to detect sense organs (probably endowed with the sense of
smell) in the short, stout-jointed, anal stylets of the Cockroach
(Periplaneta Americana), beautifully mounted by Mr. E. Bicknell.
I have recently, after reading Dr. Dohrn’s note, observed the sense
organs and counted about ninety minute orifices on each stylet, which
are probably smelling or auditory organs, such as are described by
* Hicks. Mr. Bicknell has counted more carefully than I did the exact
number of these pits, and made out ninety-five on one stylet and one
hundred and two on the other, adding, “ there were none on the under-
side of their appendages that I could see.” They were much larger
and much more numerous than similar orifices in the antenne of the
same insect, and were situated in single rows on the upper side of
each joint of the stylets. During the breeding season a peculiar odour
is perhaps emitted by the female, as in vertebrate animals, and it is
probable that these caudal appendages are endowed with the sense of
smell, rather than of hearing, that the male may smell its way to its
partner. This isan argument that the broadly pectinated antenne of
many moths are endowed rather with the sense of smelling than hear-
. Ing, to enable the males to smell out the females. I have observed the
same organs in the lamella of the antenne of the carrion beetles, which
undoubtedly depend more on the sense of smell than that of touch or
hearing to find stinking carcasses in which to place their eggs.

Motion of Microscopic Granules.—In a late number of the ‘ Boston
Journal of Chemistry, a writer who signs himself C. 8. makes some

82 PROGRESS OF MICROSCOPICAL SCIENCE.

useful comments on Mr. Wake’s views on spontaneous generation.
The author thinks it is not credible that organic germs could have
retained vitality after exposure to the heat which Mr. Wake applied
to the milk; it is not credible that eggs of infusoria like kolpoda
could have been in the milk, if that had not been exposed to the air ;
and it is to be presumed that Mr. W. would not have experimented on
milk that had not been protected. Is there any other source of error ?
Mr. W. says he put the burnt “residue” in a bottle half full of dis-
tilled water—size of bottle not given. Now the author has shown in
the above-mentioned journal that he had found it impossible to pro-
cure distilled water perfectly pure. What germs were in the distilled
water the experimenter did not know. Like hundreds of others, he
takes it for granted that there can be none, and then attributes every-
thing he discovers to the matter experimented upon, and not to the
medium used, But what did he find beside the kolpoda-like animal ?
Something like amebe, an object about the nature of which very little
is known, and a “mass of organic matter” which “had attached to it
great numbers of small infusoria, which, by continual jerking move-
ments, endeavoured to free themselves.” Here is where he believes
the great mistake of eminent microscopists has often been made, pro-
bably in part owing to inferior instruments. They have assumed that
a body with a “jerking movement,” or any movement, must be an in-
fusorium, or a germ, or some organic being. This is the important
point now for the study of microscopists. In August of last year,
Mr. D. 8. Holman, of Philadelphia, brought to him a slide which he
wished examined. It was placed under the microscope with a good
objective, and he saw the field filled with an immense number of
minute spheres, all in movement, as lively as a party in a ball-room.
He at once saw that they were what have been called monads by some
writers, germs by others, and “bioplasm” by Beale. Mr. Holman then
informed him that what he saw was albumen—white of eggs—coagu-
lated by carbolic acid; that it was prepared, mounted, and completely
sealed up from access of air, in July, 1869; and that the lively move-
ment had been going on constantly (at least it was always seen when
looked at) ever since. A few days since, with the view of verifying
Mr. Holman’s experiment, he prepared some white of egg himself, and
has obtained the same results. The whole field of the microscope is
filled with minute granules, particles, monads, or germs, all dancing
together. Now here we have matter in which it is impossible (if
human reason can pronounce an opinion on the subject) that any
animal or vegetable life can exist, and yet in which there is present
that one evidence of life, motion; and this motion has continued in
the first-mentioned slide unchanged for fifteen months. Nor is this
all. He kas prepared slides of inorganic matter,—e.g. minute par-
ticles of chalk and china clay, suspended in a solution of glycerine in
alcohol (can any life be sustained in such a medium ?)—and these not
only present the same movements, but an expert eye cannot distinguish
a particle of organic from one of inorganic matter, with the same mag-
nifying power. This movement of particles of matter in a fluid is
no new thing; it has been known for years, and the text-books on the

PROGRESS OF MICROSCOPICAL SCIENCE. 83

microscope all caution novices against being deceived by it; yet he
has good reason for thinking that many who are experts have been so
deceived. For a continued exhibition of the phenomenon, he believes
it to be essential that the matter should be so near the specific gravity
of the fiuid as to remain in suspension. In the case of chalk and of
clay, the particles in time settle in contact with the glass, and then are
motionless until dislodged by jarring them.

Structure of Crustacean Shells.—Mr. Edward Parfitt has communi-
cated to the Devonshire Association a paper on the above subject,
which is extremely valuable, and ought really to have been pub-
lished in this Journal. The subject, which is too large to admit
of our giving a fair abstract, is in great measure a summary of the
views of other writers, although there are many perfectly original
matters mentioned. This author says that he has not seen it noticed
by any writer that the pigment layer (he speaks of it now as if it was
but one, instead of being made up of a series of layers) is still supplied
with pigmentum after the shell appears to be complete, but such
seems to be the case, for he was fortunate enough, when removing the
inside membrane, or chitonous layer, to observe the pigment vessels
in situ. This inner membrane is wrinkled into folds on the side next
the shell, and these folds are collected round an areolated centre,
having a larger orifice in the centre of the areole. This is one of
the openings or communications between the animal and the corium ;
around these centres and on the folds are placed from four to seven
pigment vessels, some of which were full and others empty. The full
ones were distended and filled with minute points of red colouring
matter. The vessels are composed of two membranes, an outer and
an inner; the inner one does not entirely fill the outer one, as a con-
siderable space occurs between the two. These vessels have necks
sufliciently long to penetrate through the shell, and reach the pig-
ment layer. He could not discover the secretory glands or cells that
might be attached to those vessels, even with the highest magnifying
power at his command. The empty vessels somewhat collapse after
the pigment is discharged, as he observed several of them quite empty.
The author also describes in Cancer pagurus, on the upper surface of
the inner membrane, or on the last layer that has been added to the
shell, if a thin horizontal section be made, anda strong light be forced
through it, a number of peculiar stellate bodies. The rays are set
round about a convex disk perforated with one or two holes. These
rays have somewhat the appearance of crystalline masses, and are
principally composed of calcareous matter secreted by the crab. The
centres of these rays correspond with, and are the representatives of
the little bosses on the surface of the shell ; and through the orifices in
the centre, appear to be the chief if not the only means for the
deposit of the earthy matter. It is these convex disks which give the
curvature to the various membranes as they are secreted and fixed ; in
fact the membranes are moulded over these, and they consequently .
take their form. After a time these rays touch each other, but, so far
as he can see, they never overlap, but regular lines of demarcation are
formed ; and, curious enough, these lines form hexagons, in most

84 NOTES AND MEMORANDA.

instances as true as he has sketched them, and the lines quite as
sharp; in others they are not so regular, as a smaller one sometimes
intervenes. In time the interstices between the rays get filled up
with calcareous matter, and the rays, except their extremities, become
almost obliterated, and the shell shows only a homogeneous mass.
These rays, he presumes, are deposited more for strengthening the
membranes than for anything else, as, for instance, in the carapace of
the shrimp, and in the large claw of Pagurus Bernhardus, they are
scattered over the membranes irregularly, and do not appear to be
confined to the papille processes so strictly as in the genera Cancer
and Carcinas. The author’s plates illustrate these views fully, and
lend an additional interest to the work.

NOTES AND MEMORANDA.

Blood Stains.—We have to thank our contemporary, the American
‘Medical Investigator, for quoting some remarks which appeared
in our pages on the above subject both from the American investi-
gator Dr. Richardson, and from our English savan Professor Gulliver.
We merely mention it because the note is signed J., and we are as
yet unconscious from this to whom we are indebted.

The American Journal of Microscopy.—From the advertisement
of this journal, which is published in so large and flourishing a town
as Chicago, we expected much. We have, however, received a copy
of the magazine, and we cannot say very much in its favour. It is a
somewhat badly-printed journal of inconvenient 4to size, and is full
of a series of articles of a far lower type than is to be found in our
most familiar natural history journal, ‘ Science Gossip,’ while its illus-
trations cannot compare for a moment with those of our English con-
temporaries. We hope that it is only the first number which will have
this appearance, and that as it goes on it will get better. As it is, it
is really worthless to English microscopists.

Browning’s Microscope Lamp.—aAs illustrated on the opposite
page, we have been furnished by Mr. Browning with a new micro-
scopic lamp, which from our examination seems not only to be the
best thing of the kind made, but appears as though improvement
upon it were impossible. As shown in the engravings, it packs
into a marvellously small case, 6 inches by 3 inches, and is,
therefore, most convenient for carriage, which will be a great
benefit for those of our Fellows who are in the habit of taking their
microscopes with them to their friends. It was originally designed by
Mr. Fiddian, and bears his name upon it. The following description —
will make it clearer to the reader:—The metallic chimney being
telescopic occupies a very small compass ; the condenser fits into the
cell in front, which is also provided with plain and tinted glass for
correcting the colour of the flame. The reservoir is of brass, and will
contain sufficient petroline for six hours’ consumption. The entire
lamp fitting into the case from the top, escape of the oil is prevented.

NOTES AND MEMORANDA. 85

In trimming the lamp care should be taken that the wick is perfectly
dry, and the petroline of good quality; also that none of the oil gets
upon the metallic chimney or reservoir, or a bad smell will be given

TWdlANS |
Su aRowninc
\aw, Lon yy)

Don,
SEWN) 3S

——

off until the oil is burnt away. In using the lamp it wiil be found
convenient to slightly incline it, so as to bring the broad surface of
the flame more parallel with the surface of the mirror of the micro-
scope. When it is necessary to re-line the chimney, screw off the
sliding portion, wash out the old lining, and re-coat it with superfine
plaster of Paris. When dry it will be found ready for use—a few
minutes will be found sufficient to do this.

Photograph of our late President, Mr. Reade.—An admirable
photograph of our late President has been executed by Messrs.
Readell, of 49, Wigmore Street. It is sold at an extremely low price,
and as it has been taken comparatively recently, it is a good repre-
sentation of the dear old man.

The Microscope at the next Exhibition—A meeting was some
time since held at the Society of Arts to determine the various classes
of objects which it is desirable should be admitted for exhibition. It was
resolved to recommend to the commissioners that the following classes
of specimens, if prepared and arranged from an educational point of
view in the widest sense, should be received :—Prepared skins of birds
and animals (prepared by new processes), skeletons, anatomical figures,
microscopical objects and preparations, mineral and geological series
and specimens illustrative of the geology of various districts, fossils,
maps (physical), Ward’s cases and aquaria, botanical specimens, and
educational works on natural history.

Nobert’s Nineteenth Band.—We greatly regret that we are com-
pelled, for the third time, owing to press of matter, to omit Mr.
Charles Stodder’s interesting paper on Nobert’s Nineteenth Band.
We hope, in our next, to bring it at last, and after so long a delay,
before our readers.

(C8609
PROCEEDINGS OF SOCIETIES*

Royat Microscopican Society.
Kine’s CoLuece, January 11, 1871.

James Glaisher, Esq., F.R.S., in the chair.

The minutes of last meeting were read and confirmed.

A list of donations to the library and cabinet was read, and the
thanks of the meeting given to the respective donors.

The Secretaries exhibited two slides for opaque objects, furnished
with neat and easily-removed thin brass covers to protect objects. These
useful slides, invented by Mr. Aylward, were presented by Mr. Jack-
son, Hon. Sec. of the Lower Mosley Street Schools’ Natural History
Society of Manchester.

It was also announced that a specimen of diatomaceous earth and
shells from Caracas had been sent by Mr. A. Ernst. In announcing
this present, the Secretary said that before next meeting he would
endeavour to get the shells uncovered and the earth examined.

A vote of thanks was proposed to each of the donors.

The Chairman then announced that Dr. Lawson, the Editor of the
Journal, would bring forward the motion with reference to the alter-
ation of the day of meeting, of which notice had already been given.

Dr. Lawson said that great difficulty had arisen in the publication
of the Journal, owing to the fact that the second Wednesday in the
month sometimes fell on so late a date as effectually to prevent the
issue of the Journal on the 26th or 27th of the month, later than
which no Journal could be fairly and successfully published. If,
therefore, it should suit the convenience of the Fellows to meet at an
earlier date, much trouble would be saved in the preparation of the
matter for publication, and the Journal could be more efficiently
managed. He accordingly proposed that the future meetings of the
Society be held on the first, instead of the second, Wednesday in each
month.

Mr. Slack seconded the motion. Upon inquiry he had found that
the alteration would cause the Society’s meetings to clash with those
of other societies much less than at present, and would frequently
enable the Fellows of the Geological Society to be present, who
could not now attend. The Council had looked at all the cireum-
stances of the case, and had come to the conclusion that it would be
advisable to support Dr. Lawson’s proposition.

The Chairman having put the question that the proposed alter-
ation be made, and that it commence from March next, he declared it
to be carried, with only one dissentient vote.

The Chairman then read the house list to be proposed at the next
meeting.

The Chairman read a paper left by Mr. W. H. Ince, proposing
the appointment of two new Secretaries in place of Messrs. Slack and
Hogg, which did not find a single supporter, and fell to the ground.

* Secretaries of Societies will greatly oblige us by writing their reports legibly
—especially by printing the technical terms thus: H yd ra—and by “ underlining ”
words, such as specific names, which must be printed in italics. They will thus
secure accuracy and enhance the value of their proceedings.—Eb. M. M. J.

PROCEEDINGS OF SOCIETIES. 87

Mr. T. Charters White read a short communication “On Phy-
cocyan.”

The thanks of the meeting were given to Mr. White.

Mr. Slack read a paper “On the employment of Colloid Silica in
the preparation of Crystals for the Polariscope.”

The thanks of the meeting were presented to Mr. Slack.

Mr. B. T. Lowne read a paper “On the Anatomy of Ascaris lum-
bricoides.”

The Chairman at the conclusion of the paper testified his sense of
the great care, minute observation, and accurate delineation displayed
by Mr. Lowne in his communication.

Dr. Braithwaite congratulated the Society on the inauguration of
the new year by the remarkable paper just read, which he considered
one of the most valuable ever presented to the Society.

Dr. Lawson concurred in these remarks, and observed that so many
new facts and views had been recorded by the author that it would be
utterly impossible to comment on them then. He thought the author
merited the best thanks of the Society for his efforts.

The Chairman, in proposing a vote of thanks to Mr. Lowne, ex-
pressed the hope that he would continue his investigations, and favour
the Society at some future period with the results he might obtain.’

Mr. Hogg suggested that any Fellow who should meet with the
entozoon described should send it to Mr. Lowne. The subject was
an important one in a medical point of view, and much light might be
thrown upon it by inquiries such as those Mr. Lowne was conducting.
In medical practice it not unfrequently happened that cases similar to
that mentioned by him were brought under the notice of the practi-
tioner, in which Ascarides formed a prominent feature in disease. He
(Mr. Hogg) had had children repeatedly brought before him in order
that a horrid squinting might be corrected, in whom there were cer-
tain indications that Ascarides was the cause of the disease; and he
had not long ago seen a child, between five or six years of age, from
whose mouth Ascarides had been observed to crawl, thus confirming
the statement made by Mr. Lowne. He believed that Mr. Lowne
had corrected some erroneous impressions which were current in
regard to these animals. Regarding the investigations so ably con-
ducted by Mr. Lowne, he (Mr. Hogg) could not help wishing that in
this country, as in some Continental nations, men of such original
powers of research were enabled, through provision made by the
Government for the purpose, to carry on their labours, undisturbed
by the harassing cares of an arduous profession.

The thanks of the meeting were then given to Mr. Lowne.

In acknowledging the vote, Mr. Lowne took occasion to remark on
one point on which he had touched in his paper, that as yet we did
not know how the embryonic forms of Ascaris got into the intestinal
canal. He had also observed, contrary to the experience of some
writers on the subject, that the yelk segmentation was to be seen in
the egg while still in the body of the animal. According to Dr. Cob-
bold and some German authors, this never took place until after the
egg had been soaked for a long time in water. He (Mr. Lowne) had
found the yelk segmentation without subjecting the eggs to this pro-

88

PROCEEDINGS OF SOCIETIES.

He had not seen any embryos in the egg, not having had suffi-
He hoped, however, to

cess.
cient opportunity for developing this point.
be able to work it out in future observations.

Mr. Hogg said he had been struck by the comparisons made in
reference to these earth-worms; and it had brought to his mind
Mr. Lee’s investigations on the land-leech. He should like speci-
mens of this animal to be placed in Mr. Lowne’s hands. In this.
leech he (Mr. Hogg) had observed that the mouth and nervous system
corresponded very closely to that described by Mr. Lowne in Ascarides.

Mr. Lee said he had a few specimens of the leech referred to by
Mr. Hogg (Trocheta subviridis), which he should be happy to place at
Mr. Lowne’s disposal.

The President stated that as a new list of the Fellows would be
printed as soon as possible after the Anniversary Meeting, all changes
of residence should be immediately communicated to Mr. Walter W.
Reeves, the Assistant-Secretary.

The meeting was then adjourned to the 8th of February (the
Anniversary), when the Officers and Council for the ensuing year
will be elected.

Donations to the Library and Cabinet, from November 9th, 1870,

to January 11th, 1871 :-—

Land and Water. Lue

Nature. Weekly .

Society of Arts Journal.

Atheneum. Weekly ..

Royal Society’s Catalogue of Scientific Papers. Vol. IV.

Canadian Journal. No. 6.

On the Size of the Red Corpuscles of the Blood of
Mosehus, &e. By George Gulliver, F.R.S. .. ..

Sketches to a Scale of the Auditory Organs of certain
common Molluses. By George Gulliver, F.R.S. ..

On the Taxonomic Characters afforded by the Muscular
Sheath of the GHsophagus as ani Eee &e.
By George Gulliver, F.R.S.

The Student. No.5. New Series

The Popular Science Review. No. 38

Science Gossip. Vols. I., II., and III.

American Journal of Microscopy. No. 1

A Set of Photographs of Insect Preparations.
Thos. Hallifax, of Brighton ;

A Microscope and Set of Powers including a a
Dolland .

The Wonders ‘of the Microscope ; or an “Explanation of
the Wisdom of the Creator. Anon., 1811

On the Discrimination of Fibres in Mixed Fabries. By
John Spiller, F.C.S.

Half-dozen Slides, mounted i in brass, by Cuthbert, of Bat
and Mouse Hair, Lepisma and Podura Scales, &e. .

Half-dozen Slides of Insect Preparations, mounted by
W. H. Walmsley, of Philadelphia, U.S. ..

Two Specimens of Mr. Aylward’s New Slides for Mount-
ing Opaque Objects :

Weekly

By Dr.
by

From
Editor.
Editor.
Society.
W. W. R.
Royal Society.
Author.
Author.
Author.
Publisher.
Publisher.
Walter W. Reeves.
Publisher.
Dr, Hallifax.
The late President.
F. H. Ward, Esq.
W. T. Suffolk, Esq.
The late President.
W. H. Walmsley.

W. Jackson, Esq.

Lord Lindsay was elected a (Belay of the Soaiety.

Water W. REEvEs,
Assist.-Secretary.

ff

INA

| TuffenWest so = ' atl (00 5,

THE

MONTHLY MICROSCOPICAL JOURNAL.

MARCH 1, 1871.

I.—ANNUAL ADDRESS.*

In surveying the work of last session the Society may find much
reason for congratulation, from the variety and importance of the
papers brought before it, In a remarkable series of contributions
Dr. Pigott has made us acquainted with the nature and extent of
uncorrected aberrations in our best object-glasses. He has explained
more fully than had been done before, the advantages to be gained
by the immersion system; he has called attention to sources of
fallacy arising from what he terms evdwda (eiddla), found above and
below the true focus; he has devised new tests, and introduced a
new mode of correcting aberration by the use of his “ Aplanatic
Searcher.” The novelty of this invention consists in searching the
axis for best focal points at places intermediate between a fixed eye-
piece and the objective, and applying new and variable corrections
there. The aplanatic searcher also permits the use of a low eye-
piece of 3 inches focus (the usual A being 24). Further than this,
it is said to increase focal depth, raise the power of the objective,
improve the definition of parts seen in perspective, increase the
working distance of the objective from the object, and lessen aberra-
tion so that delicate structures invisible with ordinary means can
be perceived.

Those who haye seen most of Dr. Pigott’s experiments entertain
the highest opinion of his investigations and suggestions; but the
Searcher has not been successful in the hands of all who have tried
it, and certainly requires considerable practice and skill for its best
use.
Mr. Wenham, while controverting many of Dr. Pigott’s opinions,
has given much important information, not hitherto made public, on
-the construction of lenses; and having regard to his remarkable
skill, and to the success of his past efforts, we may look forward
with hope to his rendering still further service in bringing object-
glasses to the highest pitch of practical perfection.

From Mr. Carruthers we have received an account of the struc-

* This portion was prepared by the Secretaries.
VOL. V- H

90 Transactions of the

ture of Fossil Arborescent Lycopodiaceze, valuable not only from the
amount of accurate information it conveys, but as opening important
views of the connections subsisting between different groups of plants.

Dr. Carpenter has placed on record a description and drawing
of the ova of a fish, the parentage of which is unknown. He has
also supplied interesting details of the structure of Fusulina, and
the reparation of spines of Echinida.

Mr. EK. Ray Lankester contributed a paper on Mr. Sheppard’s
Dichroic Fluid; and our late President during his last illness
sent us another on Fluorescence v. Pseudo-dichroism, which has a
melancholy interest as the closing work of his scientific career.
Mr. Thomas Charters White also supplied some fresh details on
Phycocyan at our last meeting, and which will be found in the
February number of the Journal.

To Mr. 8. J. McIntire we have been indebted for careful re-
searches into the structure and appearances of scales of Thysanuree ;
and Mr. Joseph Beck pointed out a valuable method of investigating
the physical configuration of the markings on such bodies.

From Mr. W. Saville Kent we have received the earliest inform-
ation and description of New Silicious Sponges, of great interest to
the naturalist.

Mr. Slack brought before the Society the range of patterns to
be found in artificial diatoms; the peculiar appéarances of cracked
films of colloid silica, and the action of colloid silica in modifying
crystalline forms.

An interesting, and perhaps hitherto unrecognized creature was
brought under the Society’s notice by Mr. Barrett, and by him
called a Stentor, though it is not probable naturalists will range it
under that genus.

Mr. Bell contributed a series of researches on Fermentation and
Ferments.

Mr. Hogg described and figured a Cirearia parasitic on Lymnzeus.

The Society is indebted to Mr. Lowne for details and drawings
illustrating the anatomy of the Round Worm, and it may be safely
affirmed that his elaborate and painstaking researches possess a very
high degree of interest from the discoveries to which they have led,
and which are regarded by comparative anatomists and physiologists
as a valuable contribution to their sciences. Dr. Maddox has con-
tributed further researches on Air Dust.

Turning from microscopical investigation to microscopical appa-
ratus, the year has been remarkable for a new series of deep
objectives by Messrs. Powell and Lealand with single front lenses,
and capable of being adapted for dry or immersion use. It is
sufficient to say that these powers exhibit a very marked advance
upon the previous productions of these skilful artists. Immersion
objectives have likewise been made by other distinguished English

Royal Microscopical Society. 91

makers, and it cannot be said that the important principle involved
in their construction is now neglected in this country.

Three new binoculars have been produced: one by Mr. Holmes,
mgeniously formed of split lenses; one for high or low powers by
Mr. Stephenson, on a plan quite different from that of Mr. Wenham ;
and one by Mr. Ahrens, for high powers, constructed upon a new
principle with the aid of double-refracting spar.

For details of the optical construction of Mr. Stephenson’s
instrument, we must refer to his paper already published in the
Journal. His plan gives, for the first time in a binocular, erect
instead of inverted vision, which is often a matter of great con-
venience. Its action with high powers is really stereoscopic.

Dr. Carpenter contributed the comparative results, as regards
steadiness at sea, of instruments of moderate weight and size on the
Ross and Jackson models; and several minor matters have formed
the subjects of communication.

The mere enumeration of the topics that have been brought
before the Society during the past year will suffice to show the value
of its operations; and in addition to the publication of its papers
and ‘Transactions’ in the Monthly Journal, Dr. Lawson has ably
carried out the wishes of the Council in connecting your Society
with that publication, by bringing to a focus a great mass of micro-
scopical research made by various English and foreign observers,
and which were virtually inaccessible to ordinary students in their
scattered state.

CoNSPECTUS OF THE PRESENT STATE OF THE SOCIETY.

Honorary
Royal and Asso- Com- £1. 1s. £2. 2s.
Patron. | Foreign | ciates. | pounders.| yearly. | yearly.

Fellows.
Anniversary, 1870... 1 6 2 95 320 34 458
Since elected as earas =e Ae ee +1 ‘ss +20 |+21
Since deceased .. .. ae fe Be PF —9 ae — 9
Since resigned .. .. a Se a es —6 —5 |-I1l1

Anniversary, 1871 .. | 1 6 | 2 | 96 | 305 | 49 | 459

Booxs PurRcHASED DURING THE YEAR.

‘The Annals of Natural History,’ 44 vols., or nearly all the first
three series of the work, making it quite complete to the present
time.

‘Straus Durckheim Anatomie Comparée.’

‘The Quarterly Journal of Microscopical Science,’ vol. 18.

The numerous valuable donations have been periodically an-
nounced in the ‘Monthly Microscopical Journal.’

H 2

92 Transactions of the

I1.—OBITUARY NOTICES.

JosepH Bancrort ReApE was born on the 5th April, 1801, at
Leeds, in Yorkshire, and received his elementary education at the
grammar school of that town. He subsequently matriculated at
Trinity College, Cambridge, whence he was elected to a scholarship
at Caius College, graduating B.A. as Senior Optime in 1825, and
M.A. in 1828. His first acquaintance with the microscope appears
to have begun when he was fifteen years of age, his father at this
time having presented him with one of Dolland’s. The highest
power of this microscope he preserved, and he wished it to be given
to the Society after his decease, together with a microscope similar
in make to the one referred to. It is evident that this presentation
was an indication of the early bent of his mind. That he always
showed great attachment to science, particularly to optics, is evi-
denced by the favourite studies of his life being astronomy and
microscopy: chemistry and photography also came in for a share of
his attention. The earliest published paper I can find, connected
with microscopy, is one communicated to the ‘ Phil. Mag., in July,
18387, “On the Existence of Structure in the Ashes of Plants and
their Analogy to the Osseous System of Animals.”

The object ofthis paper was to prove, by microscopical exami-
nation of the ashes of plants, that combustion does not, as we have
hitherto supposed, destroy brute matter merely, but that it leaves
behind a purely vegetable product—a product far from being dis-
similar in its nature to the bones of animals, and having its par-
ticles undoubtedly arranged by the “ agency of a living principle.”

To this paper some further observations were made in the No-
vember number of the same year, the great object of which was to
show that there was no accidental introduction with respect to the
elements of vegetable structure, as previously expressed by Bracon-
not; and with the view of showing that the organization of fossil
plants is retained even after being submitted to the heat of a com-
mon fire, and that the white ashes of coal contained the usual forms
of vegetable matter, viz. cellular structure, smooth and spiral fibre
and annular ducts, illustrations of which accompanied the previous
paper,—in this paper he further adverted to the structure observable
in other specimens of coal, from which he inferred that the frame-
work and basis of vegetable structure in the plants of coal is not
only entirely independent of carbon, but that it has also resisted
the bituminous decomposition which has converted all the carbo-
naceous material into a highly inflammable substance. .

In the same journal (November, 1837) there is another paper,
originally read at the British Association in 1837, “On the Chemical
Composition of Vegetable Membrane and Fibre,” in which he inci-
dentally states that spiral vessels exist in the roots of dicotyledonous

Royal Microscopical Society. 93

plants; and in the first volume of the ‘ Annals Nat. Hist.’ he gives a
detailed account of the statement above referred to, viz. the existence
of spiral vessels in the roots of dicotyledonous plants, contrary to the
hitherto received opinion of English botanists. ‘They had been in
the habit of considering spiral vessels as peculiar to the structure of
monocotyledonous roots; and as proving a distinctive character be-
tween the root and stem of dicotyledons, he says, “So thoroughly has
this opinion of their position gained credit that I have in no case
been able to remove it but by giving ocular demonstration that it is
in opposition to facts.”

It was in 1887 also, whilst making some photographic experi-
ments with the solar microscope, he discovered a mode hitherto un-
attained of separating the rays of heat from those of light, so as to
enable pictures to be taken with cemented achromatic objectives with
safety, and it was at this time he made the first micro-photographs ;
the best known of these are the head of a flea, and the section of the
tooth of the Lamma, which were subsequently lithographed : a copy
of that of the flea he has left to the Society, that of the Lamma
forms one of the series selected by Owen for his Odontography ;
and it was whilst making these experiments that he discovered the
value of gallic acid as a sensitizer, and hyposulphite of soda as a
fixer on prepared paper, which stamps him as one of the foremost
pioneers in the development of photography.

In the ‘ Annals Mag. of Nat. Hist.” 1838, vol. i, there is a

aper by him “On some New Organic Remains in the Flint of
Chalk,” the object of which was to show more particularly the
fossil contents of flint pebbles and flint nodules of the chalk, and
to examine whether the flints of different strata had or had not a
common origin. He found that Xanthidiz were absent in the
Brighton pebbles, whilst several species occurred in the flint of
Kent and Surrey. Besides these singular remains which Ehren-
berg had previously described, the author detected the scales of the
ctenoid and cycloid orders of fishes which have not yet been found
in earlier formations. For comparison, illustrations of scales of
existing fish accompany the paper, and these were supplied to the
author by Mr. Yarrell.

It was in this year (1838) that he was elected a Fellow of the
Royal Society, and it was about this time that he drew the special
attention of microscopists so strongly to the great value of black-
ground illumination, that it has (though previously known) since
gone by his name. In the first volume of the ‘ Transactions of the
Microscopical Society’ is a paper which he read before the Society,
headed “The Process of charring Vegetable Tissue as applied to
the Examination of the Stomata of Garden Rhubarb,” in which he
advocates the importance of the plan for determining the form and
character Of cells and cellular tissue, &c., and also as enabling -the

94 Transactions of the

observer to say whether the stomata of plants are closed or open,
a point at that time somewhat disputed.

Tn two communications to the Society in 1842, he drew atten-
tion to the great assistance which chemistry might derive from the
use of the microscope, and goes on to state that a quantity of nitro-
gen, not exceeding the ;5t5sth part of a grain, if existing as a
constituent of ammonia, may be detected with certainty by means of
this instrument, and pointed out that ammonia was a product of re-
spiration, a fact which did not obtain credence at the time, though
justice was subsequently done to him on this point by Dr. Richard-
son, in his prize essay on the coagulation of the blood.

In the second volume of the ‘ Transactions’ of the Society is
another paper he read, “ On Animals of the Chalk still found in the
Living State in the Stomach of Oysters ;” referring to the apparent
identity between the fossil and living infusoria as of considerable
interest to the geologist, in showing that there is a connecting link
in the chain of organized beings of the same organic structure
from the secondary formation to the tertiary, and to preclude the
supposition that below the tertiary formation there are no recent
species. Reasoning from the analogy of the recent oyster, the
author examined the fossil oysters of the Kimmeridge clay, in
which he met with similar forms as coscinodiscus and others cor-
responding to those existing in the recent oyster, so as to leave
no doubt that they preserved the same beautiful mechanism, though
we cannot now detect it, for making a current to set in the direction
of the stomach, and he further infers that similar remains may be
found in still older formations. The result shows how much we
are indebted to the microscope for the confirmation of these views.

At the British Association, June, 1845, he read a paper “On
Cilia and Ciliary Currents of the Oyster,” the object of which
was to show that the action of the ciliz attached to the tentacles
produces a strong current in the water, and thus that a number
of minute living organisms (infusoria) was brought within their
influence, and thereby affords a sufficient supply of food, thus com-
pensating the prehensile organs possessed by higher creatures ; and
although it was well known that the orifice of the alimentary canal
of the oyster was in the same manner fringed with ciliz, it had not
been suggested, says Mr. Reade, or proved by any naturalist, that
the proper office of the cilie was to bring to these Acephalous
molluscs that food which they had not the power otherwise to seize.

At the Exhibition of 1851 he exhibited an astronomical eye-
piece, of his own invention, called a solid eye-piece, which was
thought so highly of as to merit special mention.

In 1861 he read a paper before the Royal Microscopical Society,
“On a New Hemispherical Condenser for the Microscope, and its
use in illustrating an important principle in Microscopic Ilumina-

Royal Microscopical Society. 95

tion,” in which he describes a plan for getting from a single con-
denser two or more pencils of light at any angle to each other—a
plan which commended itself much to those engaged in determming
the markings of diatoms, “the principle sought to be carried out
being to throw the axis of the pencil of illuminating rays in a
direction at right angles to the line to be resolved,” the great
advantage of the plan being “simple, cheap, and easy of adjust-
ment;” by means of it the dots on the N. angulatum are easily
resolved with a half-inch object-glass. This condenser he sub-
sequently improved by the addition first of one and then of another
lens to the original Hemisphere, continuing his original plan for
applying stops.

The subject of illumination in microscopic research was always
a favourite study with him, and he has often been heard to say
that the microscope was nothing without it, and it was from
having this subject so constantly before him that he was led to
the discovery of the value of a parallel beam of light in deter-
mining the true structure of the markings in diatoms and other
minute objects. In June, 1869, he read a paper before the
Society, descriptive of the prism which now goes by his name,
the value of which cannot be over-estimated ; for this inexpensive,
simple appliance gives results which are not surpassed by any of
the numerous contrivances of Wollaston, Brewster, Amici, Gillet,
Kingsley, &c., or even his own favourite kettledrum, with flute-key
adjustment, and it is interesting to note his own version of the
step which led to its discovery and value. He says, “I very fortu-
nately purchased of my friend, Mr. Powell, his little hemispherical
condenser for showing the transverse lines of that prince of puzzles,
the Amphipleura pellucida. In using this lens I saw on reflection
that a small portion only was available. I therefore covered the
whole lens with tinfoil, and then cut out opposite apertures on the
plain and convex surface, so as to obtain, in point of fact, a small
prism illuminator. This answered the purpose well, and it imme-
diately occurred to me that the equilateral prism itself might be
substituted for the prism slice of Powell’s lens. I tried it, and saw
at once the great advantages of the equilateral prism and its single
parallel pencil of light. There are, indeed, many facts and secrets
of structure which can be revealed by such a beam alone; light
virtually parallel can lead to no confusion, but the crossing and re-
crossing of an infinite number of rays produce such a multiform
shadow as to de-shadow or obliterate a true light and shade por-
traiture, which is the essence of every picture, and the very soul of
every natural representation.”

Dr. Donkin, who is now engaged in editing the ‘ Natural History
of the British Diatomacez, bears testimony to the great value of
the prism in the examination of these interesting objects.

96 Transactions of the

The prism is not only valuable for illumination of minute
markings, but it can be used as a most effective reflecting polarizer,
thus diminishing the cost of apparatus to the beginner.

His last contribution to science is an article in the ‘ Popular
Science Review, with illustrations, entitled ‘“ Microscopic Test-
Objects seen under Parallel Light and Corrected Powers,” in which
he enters more into detail as to the value of the revelations made
by the prism, and in this paper he strongly supports the views
recently advanced by Dr. Royston-Pigott.

Such is a slight sketch of the published labours of the late
President in connection with the microscope. As one of the founders
of the Society, and one who for thirty years has always taken a
warm interest in its success, he will be long remembered by all
who knew him not only for his striking appearance, but for his
kind and genial disposition, and his readiness to impart from the
rich stores of his knowledge any information he possessed.

ArtHur Raymonp Berrs, F.R.M.S., son of Dr. G. Harvey
Betts, died of typhus fever caught in investigating the condition of
Peyer's glands in the body of a patient he had attended suffermg
from that disease, and who died in Guy’s Hospital. Mr. Betts had
sedulously cultivated microscopic anatomy, and was highly com-
plmented for his knowledge of it both at the College of Surgeons
and at the London University. He made a fine collection of
histological anatomy, and was engaged in forming a pathological
one at the period of the fatal attack. rom his skill as a working
microscopist, and his scientific education, he gave promise of good
work in enlarging the boundaries of knowledge, and while we
lament his early loss we must honour the zeal that led to that
exposure to contagion which is believed to have arrested his career.

Joun Bocxert, F.R.M.S., was born in London, and educated
for the medical profession, which he did not follow, but subsequently
joined the staff at the Railway Clearing House, and became one
of the principal clerks. He was an ardent microscopist, and took
a great interest in all affairs connected with mechanical and optical
science. A few-weeks ago Mr. Bockett scratched his hand on an
omnibus, his blood became poisoned, and he died rather suddenly on
Saturday, the 28th of last month, aged 45.

The late R. J. Farrants, F.R.C.S. and F.R.MS., an
esteemed member of the medical profession, enjoyed a good and
lucrative practice up to the period of his decease. The arduous
nature of his duties, however, did not prevent him applying his
mind to the acquirements of knowledge in a large and varied field
of scientific inquiry ; accordingly, among other sources or means of
investigation connected with his profession, he was at a very early
period led to recognize the importance and value of the microscope.

To those who had the advantage of his personal acquaintance it

Royal Microscopical Society. 97

is needless to say that his indefatigable research, his patience and
perseverance, aided by high mental qualifications, ensured a com-
plete and satisfactory elucidation of the subjects which claimed his
attention, and rendered his practical use of the microscope in the
investigation of diseases as well as on other subjects most valuable.
It would be travelling beyond the object of this short notice to
allude to the contributions made by our deceased friend to medical
literature or to the many services he has performed by his careful
and exact analysis of matters submitted to him by medical friends.
It is sufficient to say that with a retiring and modest disposition he
was ever ready to give his valuable time and scientific knowledge and
experience when and wherever it was desired or likely to be useful.
Mr. Farrants was an old member of the Royal Microscopical Society ;
he was for many years elected to the Council, and in 1861-2 he
was the President. At that period it was the good fortune of the
Society to receive, through the medium of Mr. Farrants, that very
valuable instrument for microscopical writing invented by his friend
Mr. W. Peters. It is unnecessary to refer to the great pleasure
every member of the Society has derived from the admirable mani-
pulations of that instrument by the late Mr. Farrants; certainly so
long as the instrument remains to adorn the Museum of the Society
it will always be associated with the pleasant recollection of our
departed friend, whose premature death at the age of 60 has
deprived the Society of a valued member, and has left a void in a
circle of friends which it will be difficult to supply.

“Prrer Jones, F.R.M.S., late of Norton Folgate, was born in
the year 1808. He was in his youth a student at the Birkbeck
Mechanic’s Institution, where he became remarkable for his attach-
ment to the pursuit of natural history, especially botany; he also
possessed a considerable knowledge of mineralogy and chemistry.
Having passed through the usual period of studentship he became
a lecturer on chemistry, in which he obtained considerable success.
He afterwards established himself in Norton Folgate as a scientific
and manufacturmg chemist, and commenced business by giving a
series of conversaziones at his house, which were rendered attractive
by the exhibition of objects of natural history, and the employment
of the microscope in their more minute investigation. He was
elected a Fellow of the Royal Microscopical Society on the 12th of
December, 1860. He died rather suddenly of angina pectoris on
the 15th of March, 1870, in the 62nd year of his age.” *

Exxis Goopr Loss, F'.R.M.S., was born in 1807, at Canonbury
Square, Islington, London. His father carried on an old-established
business as an outfitter, at 148, Cheapside. Mr. Lobb was educated
at St. Paul’s School, and was intended for the law, but circumstances
led him to follow his father’s business, to which he succeeded about

* ‘Tinnean Society’s Journal.’

98 Transactions of the Royal Microscopical Society.

1844, and carried it on nearly to the time of his death. His incli-
nation to science and literature was early manifested. He first:
took up astronomy, and, observing from the top of his house in
Cheapside, made himself well acquainted with the constellations and
planets. He afterwards taught himself Hebrew sufficiently to read
and enjoy the Old Testament in the original. His occasional visits
to the seaside led him to the use of the microscope, and subsequently
his study of that instrument and its revelations withdrew his atten-
tion from all other recreative pursuits. He preferred Messrs. Powell
and Lealand’s microscopes to all others, and kept himself supplied
with their latest improvements and finest objectives. His attention
was devoted more particularly to what are called test-objects, and by
ereat care in manipulation and illumination he was enabled to
exhibit these, especially the closely-lined diatoms, to as great advan-
tage as any contemporary microscopist. His knowledge of the
groups of Desmidize and Diatomacez was precise and extensive, and
he made himself fairly acquainted with other branches of natural
history. His collection of objects was large, and the specimens
were generally of great excellence. He studied the phenomena of
polarized light, not only as applied to the microscope, but with the
ordinary polariscope, and larger objects, including selenite designs,
slices of crystals, &c., of which he had some beautiful examples.
He sat for many years on the Council of the Royal Microscopical
Society, and was one of the most constant attendants of both Council
and ordinary meetings as long as his health permitted. He was
warm and impulsive, but extremely good-natured, and he was always
ready to assist others by showing them how to manipulate their
instruments in the best manner by exhibiting choice objects and
testing novel apparatus. He was much visited on this account, and
highly respected for his kindness. He occasionally contributed
short papers to the ‘Transactions’ of the Society, and frequently
took part in its discussions.

For several years Mr. Lobb had suffered from rheumatism,
acute and chronic, which made locomotion increasingly difficult, but
he remained constant in attendance at the Society till about the
middle of 1870. He then became almost helpless, and symptoms
of paralysis appearing, he gave up business and removed to Selhurst,
Surrey, where he died on September 9th, 1870, aged 63. He was
interred at Abney Park Cemetery.

Annual Addyess. 99

Ill —On some Recent Investigations into Minute Organisms.
By Henry J. Stacg, F.G.8., Sec. R.M.S.

In consequence of the lamented death of our esteemed President, the
preparation of this portion of the Anniversary Address has been con-
fided to me, and it seemed advisable to select for your consideration
certain matters connected with minute organisms, which may not
only prove of immediate interest, but also suggest many topics for
further research. The microscopical work of each year assists in
elevating the lower fungi, and the whole class of bodies to which
such terms as ferments or ‘microzymes” are applied, into ever-
increasing importance ; and if the principal statements now asserted
concerning them can be established, they must be deemed essential
to the processes of life, to the production of various forms of disease,
and to all the ordinary operations by which decay disintegrates
dead masses, and prepares their constituents for fresh admission into
the circle of organic being.

One distinguished inquirer, M. Béchamp, makes the startling
announcement that blood corpuscles are aggregates of microzymes,
or micro-ferments, and can give rise to chaplets of beads, bacteria,
bacterides, and other forms. He further states that they behave like
ferments, that they give birth to cells like leucocytes, and to smaller
globules. ‘These microzymes, he says, are capable of engendering
cells in various media, and the blood corpuscle is the result of their
work.* According to this view, respiration, which has long been
regarded as a mode of nutrition, may be classed amongst the
phenomena named fermentations. Such are M. Béchamp’s con-
clusions.

In 1867 M. Béchamp, together with Messrs. Estor and Saint-
pierre, stated that the digestive action of saliva upon starch depended
upon a ferment, and was not a simple chemical action. This fer-
ment he describes as “secreted by the organisms of Leewenhoek,” as
they nourish themselves with the materials of the starch.t

In the germination of plants from seeds containing starch and
other matters, a similar process is described by M. Le Maire, who
states that vibriones and monads appear before the germination
begins.; In 1870 M. L. Coutaret informed the French Academy
that he had succeeded in showing that maltine or vegetable diastase
obtained from barley possessed the same properties as salivary
diastase ; that it is a vegetable ptyaline identical with the animal
one in physical, chemical, and physiological properties. In 1868
MM. Béchamp and Estor were led by a series of experiments to
affirm that molecular granulations, or microzymes are universally

* «Comptes Rendus,’ 7 Feb., 1870. + C. R. for that year.
t ‘Comptes Rendus,’ 1863, Sec. Sem., p. 563.

100 Transactions, &e.—Annual Address.

contained in all cells, animal or vegetable, of which they regard
them as normal and necessary constituents. These granulations,
they say, can develop themselves into bacteria.

The most startling of M. Béchamp’s statements concerning these
microzymes is, that they exist alive in chalk, or in other rocks. This
announcement was made some time ago, but in the April of last year
he detailed the results of a number of experiments to the French
Academy, showing that the microzymes existed in a fresh-water ter-
tiary limestone, as wellas in chalk, in the same condition of “molecular
granulations,” and possessing the same powers of causing fermen-
tation. He mentioned the Calcaire dOrmisson, near Narbonne—
lacustrine and middle tertiary; the Caleaire de Borbentone, near
Beaucaire—middle tertiary and marine; the Calcaire of Pignon—
middle tertiary and marine; the Calcaire néocomien de Layallette,
near Montpellier—very compact, and belonging to the lower chalk ;
and the Calcaire oolithique of the Meuse, as all capable of making
cane-sugar and starch ferment. ‘The tufaceous limestone of Cas-
telnau, near Montpellier, contained the microzymes, but acted
very slowly upon starch, so that at the end of two months, scarcely
any products of fermentation could be traced—they confined their
action to a very slow liquefaction of the starch. The same mole-
cular ferments are found by him in fossil bones, but they are in-
active at a temperature below from 35 to 40° C., so that they would
not injure the fossil ivory which is exposed to severe cold. It would
be interesting to know whether they exist in such ivory, and could
be called into operation by suitable conditions of temperature and
moisture.

M. Béchamp considers these objects as really living, and having
been in the case of the limestones and chalk for unnumbered ages
in a dormant state. Should further researches lead to the con-
firmation of this opinion, all tales of the germination of mummy
wheat, &c., will be thrown into the shade.

No very precise data exist as to the length of time during which
any kind of seed or germ can remain dormant. Amongst those
cases which may be regarded as authentic, is one cited by Dr. Car-
penter on the authority of Professor Lindley, in which three plants
of raspberries were raised by the latter from seed taken from the
stomach of a man, whose skeleton was found thirty feet below the
surface of the earth, at the bottom of a barrow which was opened
near Dorchester. He had been buried with some coins of the
Emperor Hadrian, and it is probable, therefore, that the seeds were
sixteen or seventeen hundred years old.* Many cases will occur
to Fellows of the Society, in which seeds dug up at considerable -
depths have been stated to grow; and although the mind is not dis-
posed without due examination to admit that germs, or organisms,

* Art. “ Life,” ‘Cyclo. Anat. and Phys.,’ vol. iii., p. 156.

Minute Organisms. 101

have preserved their vitality during geological epochs, it would be
difficult to assign any reason why mere lapse of time, however
great, should necessarily destroy life capable of remaining dormant
for a space like 1600 years.

With regard to the existence of organisms in minerals, reference
may be made to the experiments of Mr. Staniland Wake, recorded im
the March number (1870) of the ‘ Monthly Microscopical Journal.’

Fungi, and other minute organisms related to them, grow under
many circumstances where their nutrition might have been declared
impracticable, and preserve their vitality at temperatures which,
without proof to the contrary, would be considered as necessarily
destructive. Mr. Berkeley observes that solutions of arsenic, sul-
phate of iron, sulphate of copper, &c., though highly concentrated,
do not prevent the growth of some fungi of a low order; and he
cites the ‘ Nereis Borealis Americana,’ to the effect that a few years
ago a little mould was very troublesome to the department of Coast
Survey at Washington, developing itself in copper solutions used
for electrotyping, decomposing the salt, assimilating the acid, and
precipitating the metal round its own threads. I have found a mould
very fond of growing in saturated solutions of calcic and magnesic
chlorides. The growth of an analogous mould in dialyzed solutions
of silica in distilled water was brought under the notice of the So-
ciety some time back by Mr. Roberts and myself, and solutions of
phosphate of soda in ordinary use are usually found by Professor
Church in his laboratory in the Royal Agricultural College, Ciren-
cester, to become green with a vegetable growth. In the solutions
of citric and tartaric acids he finds colourless or grey plants appear.
He states, in a note to me, “ My experiments were chiefly made
with these three liquids, and I obtained some very curious results
by transferring the plant of one solution to another solution. On one
occasion I removed all the phosphoric acid and potash from a solu-
tion of citric acid, to which I had added a little phosphate of potash,
by introducing a fragment of a fungus from tartaric acid into it.”

M. Béchamp mentions a very curious case in the following
terms. He says: “I took very pure distilled water, and exposed
it to the contact of air in a phial closed with paper. Colourless
moulds appeared, formed of microzymes, very small bacteria, and
an extremely fine mycelium. The apparatus was put on a stove
and at the end of six months I obtamed enough alcohol to give a
large flame. At the same time a small quantity of volatile acid
and of ammonia was formed.” He asks: “Shall we say that distilled
water, carbonic acid, and the elements of air have fermented? Eyvi-
dently not ; but we may say that the moulds grew and effected the
synthesis of the materials composing their own substance, as all
yegetables do, and that they then gaye off the alcohol which they
formed by the aid of this substance,”

102 Transactions, &c.— Annual Address.

If other experimenters should be so fortunate as to grow the
same fungus and confirm these results, new views will be opened
concerning the nutrition of fungi, and perhaps some light may be.
thrown upon that of the yeast-plant, the precise action of which in
the production of alcohol is still unknown. M. Béchamp speaks of
his moulds as “ dis-assimilating ” the alcohol, as if it were an excre-
tory product. It is well known that many varieties (or states) of
fungi will produce the alcoholic fermentation, and many interesting
facts of this description, together with other suggestive matter, will
be found in the paper read by Mr. Bell before this Society and pub-
lished in the July number of the Journal. Mr. Bell has hitherto
obtained negative results in attempts to grow the common blue
mould from the yeast-plant. Professor Hoffman said, in 1865,
“ When beer-yeast is cultivated with shelter against foreign germs,
it gives rise to Penzcilliwm glaucwm, while the bakers’ yeast, pro-
duced in brandy distilleries, and kept in an almost dry state, gives
birth either to the same plant or to Mucor racemosus conjointly with
it, or, more often, to the latter only. If we sow a number of the
spores of these plants in a saccharine solution, as, for example,
honey-water, we not only obtain a great quantity of pure carbonic
acid until the sugar is decomposed, but also yeast, which yields the
same products from which it was derived.” *

M. Melsens made experiments last year on the vitality of beer-
yeast. He found fermentation possible in the midst of melting
ice, a temperature at which the yeast would not germinate. The
life of the yeast-plant was not destroyed by the most intense cold
that could be produced, about 100°C. below zero. In close vessels
when the products of fermentation gave a pressure of about 25
atmospheres the process stopped, and the plant was killed. M. Bous-
singault, who was present when this communication was made to
the French Academy, accepted the statement, on account of the
known ability of M. Melsens, but he detailed experiments to show
that other ferments had their activity destroyed by exposure to tem-
peratures much less severe, or even by ordinary frost.

It is remarkable that M. Melsens obtained a similar result when
experimenting with the supposed living particles of vaccine matter,
on which its activity has been found to depend. He kept some
vaccine matter for an hour and a half in sealed tubes exposed to
the action of solid carbonic acid and ether, cooling it down to about
78° C., and the report of Dr. Jacobs, of the Veterinary College,
Brussels, was as follows :—‘“ Two tubes have been employed to vac-
cinate an infant seven months old. Five punctures gave five pus-
tules. One tube, used on the same day to vaccinate an infant three
months old, gave, with four punctures, three fine pustules.”

The amount of heat necessary to destroy all germs is still in

* «Comptes Rendus,’ Prem. Sem., p. 632.

Minute Organisms. 103

doubt. Some perish considerably below the temperature of boiling
water, others are not injured at that heat. Some are not destroyed
by rapidly passing through red-hot tubes, and possibly others may
support for some time without injury temperatures of elevation
corresponding to those of depression in the experiments with
yeast and vaccine to which allusion has been made. Those who
believe that our earth has passed through nebulous and molten
stages, and also consider, with Professor Tyndall, that no new force:
or substance has been added, but that “ life was present potentially
in matter when in the nebulous form,” might not deem any terrestrial
heat capable of absolutely destroying this “ potentiality,” in what-
ever form it might ultimately reside. The microscopical student
can only expect his special modes of investigation to throw an in-
direct light upon problems of this description, the solution of
which may be altogether beyond the bounds of physical and
chemical research ; but it may be well to consider whether we may
not encourage fallacies by too vague and general an employment of
such terms as “life,” “vital,” “ vitality,’ &c., and this is the more
necessary when we watch or take part in the still unsettled con-
troversy of the heterogenists. Some of the phenomena exhibited
by what we call living organisms are obviously physical, others
purely chemical, and we arrive at last at intelligence, thought, and
manifestations of will, between which and any exhibition of physical,
chemical or electrical force, we cannot trace the slightest connection
of congruity or resemblance; nor does science offer, or even promise
to offer, any explanation of the way in which they are connected
with the action of nerve or brain. To refer all to that imaginary
entity “vital force,’ would be an obvious blunder in logical method ;
and if we excludemental operations, as being beyond the domain of
mere “vital force,” it will seem that we do not know anything
that would justify ascribing the simplest life processes of such
molecular organisms as M. Béchamp describes under the name of
microzymes, and the complex relations and correlations of phenomena
in the higher animals, to variations in the quantity of one vital
principle. Dr. Lionel Beale, the most ardent supporter of the
vital force doctrine still extant, says that “all truly vital phenomena
must necessarily be altogether out of the range of mere physical
investigation.” Were this dictum worked into a definition of vital
phenomena, it would exclude all that living beings do, or suffer, in
accordance with physical or chemical laws; and new discoveries. in
synthetical chemistry would leave for vital force scarcely anything,
perhaps nothing, but a method of directing and co-ordinating
chemical and physical forces to vital ends. Science can make no
use of, but must be injured by, terms that lack precision; and the
objection to referring a particular action to “ vital force” is, firstly,
that.no one can tell us exactly what is meant by the term, and
VOL. V. I

104 Transactions, &c.—Annual Address.

secondly, that experience does not favour the reference of actions
in living structures to a sort of force which no science can inyvesti-
gate, as each year adds to the number of operations performed by
chemists, like Berthelot, with the ordinary apparatus of the labora-
tory, and resulting in the formation of substances which the vital-
forcists had previously declared their special entity, only, could
produce. Granting at once that there are mysteries in life, even of
the humblest description, which defy all effort at scientific explana-
tion, and frankly confessing where knowledge stops and absolute
ignorance begins, we may still yield assent to the exclamations of
M. Berthelot, in his ‘ Lecons sur les Methodes Générales de Syn-
these en Chimie Organique.’* After stating that the progress of
science is manifested in two lines, one that of philosophical ideas,
and the other of practical application, he exclaims, “ Shall I speak
in the language of philosophy of those profound notions which
chemistry affords concerning the constitution of matter, eternally
durable, in the midst of perpetually changing appearances? What
can be more striking than the conception of living beings, as
formed by the assemblage of certain definite substances, comparable
in their fundamental properties with mineral bodies formed of the
same elements, obeying the same affinities, the same laws, chemical,
physical, and mechanical: what more important than the reproduc-
tion of these substances, or first materials on which living organisms
operate, by the sole play of mineral forces, and by the simple reaction
of carbon on the elements of air and water? .... The general
problems of the nutrition of living beings are chemical problems. It
is the same with those of respiration. The study of these problems
rests upon data supplied by organic chemistry. In the tissues of
animals, as soon as the solids, the liquids, and the gases have been
placed in reciprocal contact, under the influence of certain move-
ments, resulting from the nervous system, and a special structure,
which we know not how to imitate, affinities develop between these
solids, liquids, and gases, which are purely chemical, and the com-
binations to which they give rise result exclusively from the laws of
organic chemistry.”

Reverting to the action of ferments, it may be remarked that
fermentation was the subject of some lectures delivered by Dr.
Williamson before the Society of Artst last year. In reference to
the microscopy of the organisms concerned in processes of fermen-
tation, they can scarcely be considered as up to date, but it may be
well to glance for a moment at the “ conclusive” reasons alleged by
the Professor for ranging the ferments amongst animals rather than
plants. Dr. Williamson says: “‘ These organisms assimilate, or, to
use a homely phrase, they feed upon very complex substances ; they
give off during thew vital functions less complex substances.”

* Pp. 8 and 9, + ‘Soc. Arts Journ” ‘Pharm. Journ.’

Minute Organisms. 105

Another reason for considering them animals, he states to be, “ that
whereas plants require for their growth the light of the sun—in
fact, their very growth is a process of absorption of heat by their
leaves from the rays of the sun—and plants by so doing render heat
latent, as we sometimes express it, that is, they cause an apparent
disappearance of heat, and lower the temperature of surrounding
space; animals, on the contrary, give off heat during the exercise
of their vital functions, and do not need to be exposed to heat or to
continuous light for their growth.” This is surely an astonishing pas-
sage, and physiologists will feel compelled to demur to the assertion
that heat is not necessary to the performance of the vital functions
of animals, and that animals in general could live without light. If
animals gave out all the heat they wanted, by their own processes, we
might in this cool climate simplify clothing, abandon the domestic
winter fire, and never have our benevolent sentiments shocked by
tales of fellow-creatures frozen to death. It is certainly an error
to say that “animals do not need to be exposed to heat,” and also
to represent plants as simply heat consumers, and not also heat pro-
ducers. Mr. Grove, in his ‘Correlation of Physical Forces,’ says,
“ Heat is an immediate product of chemical affinity. I know of
no exception to the general proposition, that all bodies in chemically
combining produce heat.” It is from this general law that plants
do evolve heat in their processes of combination, and at times they
evolve enough to produce a striking elevation of temperature, as is
well known. It cannot be affirmed of all fungi, acting as ferments,
that they feed upon complicated substances, though some do ; and
on the other hand, the food of other plants is not at all times, and
always simple. For example, in the last edition of Dr. Carpenter’s
‘Principles of Human Physiology,’ edited by Mr. Power, I find an
allusion thus made to a paper by Risler, “ On the Absorption of
Humus by Plants,” and on the functions of ordinary plants as com-
pared with those of Fungi:—“ The exhalation of carbonic acid is not
peculiar to fungi or germinating embryos, for it takes place durmg
the whole life of flowering plants, both by day and by night, in sun-
- shine and in shade, and from their green as well as from their dark
surfaces. And it is not improbable that, as in the case of fungi, its
source lies partly in the organic matters absorbed ; recent investiga-
tions having rendered it probable that plants really take up and
assimilate soluble humus.” Now soluble humus is a highly complex
-substance, probably consisting of various acids and ammonia, and
requiring to part with some of its carbon to form the normal con-
stituents of plants.

It is often a matter of interest to the microscopist to say whether
organisms, occupying a sort of border-land, belong to the animal
or the vegetable kingdom, and in many cases this cannot be done
with precision or certainty. Some remarks of Boussingault will

12

106 Transactions, &e.—Annual Address.

assist us to arrive at right conceptions of these matters. They will
be found in a paper read before the French Academy, in 1864, on
“ Vegetation in Darkness.”* He pointed out that the nutriment
contained in seeds and in animal eggs was of the same description :—

Eces. SEEDs.
“ Albumen. Albumen.

Fatty matters. Fatty matters.

Milk sugar, glucose ? Starch, dextrine able to form glucose.
Sulphur, phosphorus, entering into Sulphur, phosphorus, entering into

organic compounds. organic compounds. :

Phosphate of lime. : Phosphate of lime.

Water in great proportion. Water in small proportion, cellulose.”

The seed requires moisture-and oxygen from the air, and its
mode of germination is analogous to the incubation of the egg.
Citing the ‘ Statique des Etres Organisés’ by himself and M. Dumas,
he observed: “ We said (in 1841) at certain epochs, and in certain
organs, the plant becomes an animal; that like an animal it be-
comes an apparatus for combustion; that it burns carbon and hy-
drogen ; that it produces heat ; that the sugar, or starch converted
into sugar, furnishes the first materials by which this character
is developed. ‘The experiments I now bring before the Academy
complete this statement, by showing that a plant developed in the
dark, with stem, leaves and roots, behaves like an animal during the
whole duration of its existence.” M. Boussingault proceeded to
show that while the animal, in addition to emitting heat and car-
bonic acid in respiration, modified by respiratory combustion a
portion of the albumen it consumed into the nitrogenous crystalline
compound urea, the plant growing in the dark transformed part
of its albuminoid matter into a crystalline principle, asparagin, an
amide like urea, and transformed into aspartate of ammonia with
as much facility as urea becomes transformed into carbonate of am-
monia. ‘This asparagin is found in the juices of the cells, and thus
differs from urea in not being an excretion. While the higher
pnts are not so sharply and completely separated from the animal

ingdom as was formerly supposed, we must not be surprised if
organisms belonging to, or related to fungi, and whose mode of nu-
trition bears strong resemblance to that of animals, should often be
difficult to classify ; and similar difficulties are experienced in dealing
with some of the lower organisms living in ocean depths, and which
seem to perform the functions of plants.

The connection of minute organisms of the nature of ferments
with disease has occupied attention during the past as in preceding
years. Dr. Lionel Beale, in a paper published in the last number
of the Monthly Journal, protests against the opinion entertained by
Mr. Simon and many others, that “each contagious disease is pro-

* “C. R., 1864, Prem. Sem., 917.

Minute Organisms. 107

duced by a specific vegetable organism ;” and he says it appears to
him that the arguments break down as soon as they are analyzed,
and the facts in their favour carefully investigated.” Dr. Beale refers
the mischief to minute living particles of ‘“ bioplasm,” and he says,
“these resemble one another in general appearance. Neither by its
form, chemical composition, or other demonstrable properties, could
the vaccine germ be distinguished from the small-pox germ, or the
pus germ from either. All resemble the minute particles of the
bioplasm of the blood from which they have probably been derived,
but from which they differ so remarkably in power.” The doctrine
of absolute species propagated by special germs capable of no other
development than one having correlation with a particular disease in-
volves difficulties which require great consideration on the part of
naturalists and physiologists, and is obviously connected with ques-
tions of the permanence of species, and the production of varieties.
It may be doubted whether all living particles in plants, or which are
plants, could be distinguished by any means with certainty from
Dr. Beale’s animal bioplasm particles ; and we are not without recur-
ring evidence that vegetable organisms may be causes of disease.
Dr. Balestra* has lately adduced reasons for supposing that a micro-
scopic plant producing an appearance like oil spots on the water of
the Pontine Marshes, and which, on examination, is found to have a
form like that of the Cactus Peruviana, is the source of ague poison.
He describes its spores as y,/55th of a millimétre in diameter, and of
a characteristic form. He found that small quantities of sulphate
of quinine and arsenious acid or sulphite of soda altered them in a
striking way and killed them. He traced them in the marsh air, and
believed that an ague with which he was twice attacked was occa-
sioned by inhaling them—the fit coming on after having involun-
tarily smelt water in fermentation and covered with the plants and
their spores.

The valuable researches of M. Pasteur and others into the cause
of silkworm diseases are too well known to need extensive reference,
and by the methods he proposed of obtaining eggs from healthy
moths kept in seclusion, an enormous gain has been secured to the
cultivators. M. Pasteur distinguishes three principal silkworm dis-
eases, muscardine produced by spores of Botrytis Bassiana, and pé-
brine produced by “corpuscles,” found in all stages from the egg
to the moth, in all its tissues and liquids, in the silk material, and
in the dejections. These corpuscles, he tells us, multiply by germs,
’ but those which are found in the dust and rubbish of silk farms, he
says, are dried up and deprived of life. Those which find their
way into eggs areactive for mischief. They may be introduced by
birth and descent, by inoculation, or by food. Another disorder
called la fldcherie is produced by a ferment which develops chaplets

* “Comptes Rendus,’ 18 July, 1870, p. 235.

108 Transactions, &e.—Annual Address.

of beads. These bodies have their origin im a fermentation of
the mulberry-leaves. The investigations of M. Pasteur establish the
fact that bodies belonging to the class of ferments can be causes of
disease, and they afford a striking instance of the value of the micro-
scope in detecting such causes, and checking their action. The chief
silkworm diseases arise from objects which the microscopist furnished
with the data supplied by Cornalia, Quatrefages, and Pasteur can
recognize with certainty, but the same cannot be said of other bodies
known or supposed to have morbific properties, some of which are
alike in appearance, while others, more susceptible of discrimination,
bewilder an investigator when he tries to trace certain consequences
back to them as an efficient cause.

Dr. Burdon Sanderson considers it probable that “every kind
of contagion consists of particles ;” but then come the questions of
What are these particles? What is their origin? and How can we
discriminate one from another. Referring to Hallier’s researches
and discovery of colonies of micrococci in every contagious liquid,
he observes: “ Assuming this observation to be correct, and that,
as Hallier believes, the microzymes are identical with the con-
tagious particles, it is of no value as a means of distinguishing the
various contagia from each other, unless the micrococci are capable
of differentiation ;’ which last words seemed to be used inadvertently
for susceptible of discrimination. “ Haller,” he continues, “ admits
at once that no specific distinctions can be founded on their forms or
appearances, as actually observed in contagious liquids. He seeks
for the required characteristics in their development, and maintains
that, although the microzymes of two different classes are exactly
the same, the higher forms to which they severally unfold are spe-
cifically distinct.” He goes farther than this: from the higher
forms obtained by cultivation he claims to be able to reproduce con-
tagious microzymes. Dr. Sanderson does not consider that Hallier
has proved his case, and this seems to be the general opinion in this
country ; but what is here said may induce Fellows of this Society
to make experiments with the lower forms of life, and work out dis-
puted or doubtful points of fungoid development. Among the
fungi to which Haller imputes disease is the Pleospora herbarum,
the form that is parasitical on darnel being in his opinion the cause
of sheep-pox—a thing which Dr. Sanderson observes has not been
tested by actual experiment.

Whether we call the organic particles in question “ bioplasts,”
or “microzymes,” whether we suppose them animal or vegetable,
and whatever theory we form as to their origin, there are three
conspicuous modes by which they may become disseminated, viz.
by water, or by air, or in food either liquid or solid. The Yearly
Report on Public Health, by Mr. Simon, published last year, con-
tains a paper by Dr. Thorne, “On the Effects produced on the

Minute Organisms. 109

Human Subject by Consumption of Milk from Cows having Foot-
and-Mouth Disease,” and his conclusions are that “a disease ap-
pears sometimes to have been produced in the human subject when
the milk of cows suffermg from the disease has been freely used
without being boiled ;” but he adds, “‘in a very large number of
cases the milk of cows undoubtedly affected has been used without
producing any noticeable marked effects.” This seems to be analo-
gous to the well-known fact that persons or animals exposed to
contagion do not always catch the diseases which those contagions
are supposed competent to produce; and this suggests the important
inquiry as to what conditions the contagions require for their mis-
chievous activity, and also whether microzymes, which under some
circumstances produce disease by their processes of growth or de-
velopment, can develop under other conditions without inducing
such results. In the case of cow’s milk infected with germs of
foot-and-mouth disease, Londoners have been supposed to have
derived advantage from the well-known practice of the trade to
distribute their article in the mild form of milk and water; but the
addition of the aqueous fluid is not always contributive to our
safety, and Dr. Ballard has recently published a pamphlet detailing
a series of cautious researches, which render it probable that a fatal
outbreak of typhoid fever in Islington may have originated through
the milk of a particular establishment being mixed with water from
an underground tank, which by the work of rats had been made to
communicate with some old drains. Unfortunately, no microscopic
examination of the water from this tank was made at the time of
the fever, as its existence was not then known, and at a later date
Dr. Bernays stated that its analysis coincided with that of the New
River Company supply.

That air conveys with its currents to various places germs,
spores, and particles of different substances, has been long known ;
but the general public has been led to take much interest in the
matter, and perhaps to entertain exaggerated views of danger,
through Professor Tyndall’s lectures and exhibition by the electric
light of the particles which constitute the motes in the sunbeams,
and which have been gazed at for generations. Some very interest-
ing researches on the particles floating in air will be found in
Pouchet’s ‘ Heterogénie, published in 1859, under the head of
“ Micrographie Atmospherique,” in which he shows that the greater
portion of these particles consists of small fragments of various
materials exposed to friction and disintegration, and by no means
comprises the quantity of eggs, spores, &c., that some have imagined.
In other investigations it was found that the air of rural districts
contained, as might be expected, fewer particles than that of towns,
and mountain regions were almost free from them.

Dr. Maddox brought this question before us in a paper which

110 Transactions, &e.—Annual Address.

was published in the Journal for June, 1870, with drawings of
an apparatus employed to collect the particles, and of the objects
he found, and he has furnished us with further particulars.*
Dr. Maddox lives near Southampton, and the result of examin-
ing the collections of atmospheric particles for forty days, showed
that “the air cannot be considered as loaded with microscopic
germs; the largest number visible and counted as such on one
cover being twenty-one (not including bacteroid bodies).” In the
August (1870) number of the Journal, Mr. Metcalfe Johnson, of
Lancaster, described an “ Air-Sieve,” and stated that he found vary-
ing quantities of Monas lens, and of organic matter. The presence
of monads he found best ascertained by examining the surface of
the distilled water, which in his apparatus trickles slowly over a glass
plate in contact with the air. In the same number, Dr. Sigerson
describes results of his examinations, and gives a variety of instruct-
ing particulars coinciding in the main with the researches of Pouchet.
In iron-works he found curious little bodies, mimute bombs or
balloons, from 1—500" to 1—5000" in diameter. One of his con-
clusions is, that “the theory of the panspermists seems unfouaded
on fact—that there are no hosts of germs always floating about in
the atmosphere, invisible and maleficent as genii in Eastern stories.”
Several times he “came upon atmospheres where a sunbeam could
not be seen for want of motes.” He considers contagions to consist
of albumenized matter in a state of motor change, and he speaks of
granules, resembling exudation granules, found in a fever atmo-
sphere.

In the ‘Proceedings of the Bristol Naturalists’ Society’ for 1869,
ig a paper by Mr. Stoddart, on the contents of rain water collected
in Bristol, showing the matter brought down from the atmosphere
by descending showers. One specimen collected in North Street con-
tained 10°31 grains of solid matter per gallon, including sulphates
and chlorides of ammonia and soda, nitrate of ammonia, pure sul-
phuric acid and carbonaceous matter and greasy organic matter, the
last to the extent of 2°63. A gallon collected in King’s Square
yielded 6°76 grains of solid matter, the ‘‘ greasy organic matter ”
amounting to 1°43. It is to be regretted that Mr. Stoddart did
not add the results of a microscopic examination.

From the consideration of the matters floating in air, we pass
naturally to the question of Spontaneous Generation, or as it is
better to call it, Heterogenesis, which still engages the attention of
many microscopists, and cannot be affirmed to be decided. Professor
Huxley made this subject the topic of the Address he delivered to
the British Association last September, in Liverpool; and although
it would certainly be possible to place the evidence adduced by the
‘‘ Abiogenists” in a stronger position than he has done, the ma-

* See Journal for February.

Minute Organisms. 111

jority of those who have paid attention to the controversy or
engaged in experiments, will coincide with his statement that
“with organic chemistry, molecular physics, and physiology yet
in their infancy, and every day making prodigious strides, I
think it would be the height of presumption for any man to say
that the conditions under which matter assumes the properties we
call ‘vital’ may not some day be artificially brought together.
All that I feel justified in affirming is, that I see no reason for
believing that the fact has been performed yet.”

Dr. Bastian’s experiments and statements have been the subject
of brisk controversy, and he cannot escape the charge of haste, and
in some cases want of sufficient care. Cautious experiments made
by others have shown that glass vessels are acted upon by such
solutions as he employed ; and Dr. Frankland describes in ‘ Nature’
(January 19th) glass splinters and spheroidal bodies, which he
says were evidently rounded particles of glass, obtained by exposing
carbonate of ammonia 15 grains, phosphate of soda 5 grains, dis-
tilled water 1 ounce, to a high temperature in tubes of hard Bohe- .
mian glass. Dr. Frankland observes that the movement of certain
particles was evidently Brownian ; but without doubting that his
particles possessed no life, we may ask is that sort of motion any
proof of it 2? Would not living bodies, if small enough in proportion
to their specific gravity, be affected with this motion just as inor-
ganic bodies of the same weight, size, and form would be ?

Theoretical conclusions such as those resulting from a consi-
deration of the Pangenesis hypothesis of Darwin, together with
inferences from a host of facts, lead us to believe that vital proper-_
ties may exist in particles too small for microscopic investigation,
or even visibility. Dr. Pigott estimates the spherical error of what
we have considered fine objectives as the 1—50,000" ; and we have
glimpses of bodies less than that size which are alive, and the struc-
tures of which must be far too minute for examination by any
instruments we can at present hope to possess. We are liable not
only to be baffled by minuteness of size, but also by close approxi-
mations to homogeneity of structure, colour, and refractive power.
We want to see the ultimate molecular structure of bodies on which
dialytic and perhaps chemical actions depend, and we have no
means of doing it. The controversy between heterogenists and
other thinkers may thus elude all direct research, but it would, on all
grounds, be a mistake to discourage investigations, because they are
carried on in the hope of establishing conclusions that militate
against existing ideas, or theories that have been long accepted.
We must in our special pursuits avoid the method of reasoning
resorted to in old times by supporters of incorrect theories of
astronomy, and which is still occasionally used by men of some
pretensions to scientific knowledge. To put such reasoning in a

112 Transactions, &c.—Annual Address.

logical form, it would stand thus:—The Creator assigned the best
orbits to planets; circular orbits are the best, therefore the orbits
of planets are circular. We must not assume that we know all
about the origin of life, and say, “the best principle is that of
omne vivum ex ovo or ex vivo, therefore such is the origin of all
living things, subsequent to a primal act of creation.” We may
not venture to say how, but we may be sure that in the future, dis-
coveries will be made that will deal with many opinions we now
hold, as past discoveries dealt with the errors that preceded them.
Science comes with startling surprises to the most gifted minds,
and let us hope it may be ours to hear without alarm what
Tennyson calls that

“ Bridal dawn of thunder-peals, which comes
Whenever thought hath wedded fact.”

Transactions of the Royal Microscopical Society. 113

IV.—On a New Form of Binocular Eye-piece and Binocular
Microscope for High Powers. By C. D, Anreys.

(Taken as read before the Royau Microscopica Society, Feb. 8.)

Iris now about four years ago since I made a binocular microscope,
the prism of which was made of Iceland spar. It was not made
publ at the time through any of the journals, as I could not get
it to define so perfectly as I wished. There were, however, several
gentlemen to whom I showed it at the time, and explained its con-
struction ; among these were Dr. Millar, Mr. Wenham, and several
others. Mr. Wenham then referred to his having tried to make the
same some years previously, and said that I had been more success-
ful than he was. By means of much labour and perseverance I
have, since the time referred to, brought the idea to a successful
issue, one which at starting I had scarcely contemplated.

Through having been called upon to make many hundreds of
prisms for the beautiful arrangement by Mr. Wenham, the subject
of binocular vision is one in which I feel an especial degree of in-
terest, and in consequence I have been led to try if there were not
some other combination that could be made, by means of which we
might use the high powers as well as the lower ones, and still have
a stereoscopic effect, both fields bemg equally and evenly illumi-
nated without any extra or special illumination. I believe that I
have now succeeded in doing so.

The means of effecting this is, as I said, obtained through the
agency of Iceland spar. I make a double-image prism out of spar
alone, for I get just double the amount of separation of the rays
that I should from one of glass and spar. I cut the spar in a way
that would be somewhat difficult for me to explain satisfactorily.
I grind one piece to an angle of about 40°, and then cut it in two,
and reverse them, placing the thickest parts opposite each other, and
cementing them together with balsam. At the same time I cement
in a similar manner a piece of thin parallel glass on each end, to
preserve the surface; and I find that by this addition I also get
better definition. In each of these pieces of spar there are two
images, the ordinary and the extraordinary rays; and when these
two pieces are balsamed together we can only see two, that is the
extraordinary rays that I make use of, the two ordinary ones
being shut off; and I get two perfect uniform images of the same
separation out of one piece of spar. This prism divides the rays
about 2} inches in 8 inches, which I find very convenient for the
microscope, allowing rack-work for the different widths of sights.
Of course there is a great deal of colour in each of these rays,
but I do away with this by placing a double-wedge flint glass
prism of an angle of 25° (as shown in the drawing) over the
double-image prisms, and as close as I can get them just to allow
the fields to be illuminated all over; and these prisms cause the

114 Transactions of the

rays to cross; and being very close to the double-image ones we
do not get all the rays of light, only sufficient to be illuminated,
which gives it a very good stereoscopic effect ; and these flint prisms
bring the centre rays about the
same distance apart as they were
before they crossed.

In this arrangement you re-
quire a special pair of bodies, both
being at an angle. ‘This is the
best plan, because you do not lose
so much light, being closer down
than the binocular eye-piece I have
made, for I was asked by several
gentlemen if I could not make a
binocular eye-piece for high powers,
as they did not wish to have any
more alterations made on their
present form of microscopes. This
I have succeeded in doing. I make
the prisms go down the upright
tube about 5 inches, and the rays
cross in this tube as represented in
the drawing, and about 44 inches
above the upright tube. This is a
severe test for it, the rays travelling
so far; loss of light we can make
up for by having a stronger light
or a larger mirror.

This arrangement may not be
quite so good as Mr. Wenham’s for
low powers, but for high powers I
cannot conceive of anything finer.

This system also gives one of
tris the most perfect micro-polariscopes

feet that we can haye, for the double-
image prism takes the place of the

iui yf OL

Analyser; and the prisms being
worked so very true compared with
what the Nicol’s prisms in general
, are, we get the full field, but we
can use only one body at the time
F unless there is a Nicol’s prism in

EXPLANATION OF THE FIGURE.
a,a, Double-image prism of calc-spar, lined with glass6. c, Double flint
prism for achromatism of the light. d, The ray of light from the object-glass.
Rack-work and milled head are shown.

Royal Microscopical Society. 115

one of the tubes. This is because of the way in which the double-
image prisms are ground ; that is, equal to one Nicol’s prism turned
round 90°; hence you cannot get the same colour in each field
unless, as I say, a Nicol’s prism is placed in one of the tubes or
on the top of the eye-piece.

I think that this binocular eye-piece might be used with ad-
vantage in the telescope, for by its means we could tell whether the
object examined shone by its own light or by reflected light.

V.—On Crystalline Forms modified by Colloid Silica.
By Henry James Sxack, F.G.S., Sec. R.M.S.

(Taken as read before the Roya Microscopicat Socrery, Feb. 8.)
Puates LXXVII. ann LXXVII.

TE remarks in this paper must be regarded as in continuation of
those previously communicated to the Society. The nature of the
action of colloid silica in modifying the patterns obtained in preparing
various crystals for observation with the microscope and polarizing
apparatus, has already been explained, and we may at once proceed
to the consideration of the figures in the accompanying Plates.

Fig. 1 represents a portion of a pattern obtained by heating
and quickly drying a drop of a strong solution of cadmic chloride
prepared with distilled water containing colloid silica. The whole
pattern is approximately circular— what is shown is included
between two radu and a curved line near the outer circumference,
about 1—10". In this slide crystallization has suffered extreme
interruption, and the result is a deposition of the salt in a form
rudely, but strikingly resembling the patterns of sections of certain
echinus spines. In the centre are some clear cellular-looking spaces,
and on all sides proceed radial lines, with concentric lines at inter-
vals. Fig. 10 shows the same salt in a crystalline flower pattern.

Fig. 2. Hippuric acid prepared with the silica. Here we see
the action of radial and tangential forces. The spirals, in bands from
1—170" to 1—200", appear to be thickened and slightly-raised
portions of the general structure, which is a modification of the
well-known grouping of radiating needles into circular patterns.

The strong lines show silica cracks.

Fig. 3, hippuric acid and silica, exhibits graceful floral curves,
in which the angular character of simple and pure crystallization
is modified into organic outlines like those of exquisitely-shaped
flowers and foliage. High-power views ($th and A or B eye-piece)
exhibit multitudes of minute markings, cracks, and modifications of
level. Size from about 1—30" to 1—100".

Fig. 4 is taken from a slide of hippuric acid and silica. This
slide contains circular groups of various sizes with curiously-frilled

116 Transactions of the Royal Microscopical Society.

borders springing from the points of elongated needles. Most
of the patterns run into each other, and they all show Maltese
crosses of colour with the polariscope. The artist has shown small
rosette patterns from this slide. Some rosettes as small as 1—400",
others 1—100".

Fig. 5. Potassic chlorate and silica. Some of the various
patterns obtained with this salt. The architectural, pedestal-look-
ing group exhibits curves as well as angles. Many flat crystals
show silica cracks, which look as if engraved or incised: they do
not go through the substance. Pedestal group about 1—40".

Fig. 6. Cupric sulphate and silica. ‘This contains figures
selected from a variety of patterns. The sketch exhibits a curved
floral pattern of considerable complexity and of great beauty with
the polariscope, and also small rosettes. The latter, with high-
powers, is seen full of minute workings, approximately like diatom
beadings. Rosettes from 1—50” to i:

Fig. 7. Cupric sulphate and silica. A nautiloid pattern, com-
posed of curved lines, the chief arrangement of which is from right
to left, as seen in an inverting instrument, with parts running the
opposite way. The imbricated scale or feather-like aspect results from
silica cracks and modifications of level and thickness. In this slide
also is shown what in former notes was designated the “pavement
pattern.” Nautiloid pattern rather less than 1—40" long diameter.

Fig. 8. Cupric sulphate and silica. Complicated spirals, with
minute bead-like divisions. Many of the spirals in this slide run
into each other and are confused. The circles containing the spirals
up to about 1—34".

Fig. 9. Salicine and silica. Small flower patterns. Many of
them, with 1th and A or B eye-piece, exhibit radial lines of minute
beads and granules, arranged to produce effects most like actino-
cyclus. Small ones 1—400".

Fig. 10. Cadmic chloride and silica. See remark at the end of
description of Fig. 1. Size from rather more than 1—100” to
very minute.

Fig. 11. Tartaric acid and silica. "This combination gives a mix-
ture of irregular pavement pattern, with more or less floral patterns.

Fig. 12. Salicine and silica. In this slide the tangential forces
have developed the radial patterns seen in common slides, with
flowering curves like fine foliage. The variations in thickness, &c.,
give rise to a greater range of tint and more colour harmony than
in ordinary slides. Floral pattern about 1—8".

Fig. 13. The patterns in this slide are extremely complicated
and elegant. Very delicate fan-shaped radial groups give the
appearance of a delicate tissue. They spring from needles, and
are exquisitely fringed. Some complete circles about 1—50".

eee WecroSéarieal Journal: Maxch LGN PL LXXVI

Cacd.Chlor.

P.Chlor Copper. 2:
fen West se:
haa Crystals Modified by Golloid Silica.

@nadeee)

VI.— Obyect-glasses and their Definition.
By F. H. Wenuaw, Vice-President R.MLS.

I may offer some excuse or apology for the controversy under the
above head with Dr. Pigott. Why he should state that he has
incurred my displeasure on the items recapitulated in the last
Journal I am at a loss to imagine, as I have not been out of
temper, or had any feeling of the kind. At the outset he made
some statements concerning object-glasses, which appeared to me
questionable, and fairly threw down the gauntlet by saying that
“the battle of the glasses will have to be fought.” All these
questions must be resolved in a practical sense at last. It could
not be expected that any of the professional makers would express
opinions, or divulge their practice ; and seeing grounds for objection,
I accepted the challenge, and during the controversy, or “ battle,” in
the usual course I bring forward any facts that will tend to prove the
error. With every desire to arrive at the truth this is oftentimes a
source of irritation.’ Events have shown that the first points need
not have been dwelt upon. I might well have left the beaded ap-
pearance of the Podwra to the decision of others. I have lately
looked over a great number of slides, and now have particular spe-
cimens which easily develop beads with a 4 inch. ‘Traced to its
source with the highest powers, this is evidently caused by inter-
costal corrugations of the membrane. I therefore endorse the opinion
of the most diligent and accurate observer of this class of objects,
that the beads are “ ghost beads,” and the!!! spines are not “ spwr-
ous,” as Dr. Pigott states. We are all working with the same
view of obtaining results, and must admire the industry with which
Dr. Pigott has been elucidating the primary laws of refraction and
reflexion, by his papers in the Journal and ‘ Transactions’ of the
Society during the past year; and though the caustic curves, and
figurés of aberration from a variety of concave and convex reflecting
surfaces, are to be found in Potter’s and other treatises on Optics,
still the rehearsals may be welcome to those who do not habitually
refer to these works.

With respect to the immersion lens (the true advantage of
which I have never disputed),* I must state that Figs. 2 and 3,
page 23, Jan. 1871, are not mere imaginative diagrams arranged to
meet a far-stretched theory, but transcribe a positive fact. All the
distances there shown, both for thickness, radius, diameter, and focal
distance, were taken from actual and repeatedly-verified measure-
ments, when adjusted for the same object and cover. ‘The aperture

* It might be inferred from the tone of Dr. Pigott’s communications, that he
defends the immersion principle against a number of opponents——Where are
they ?

118 Nobert’s Nineteenth Band

remains the same in each, and of course if Canada balsam is run
under the cover to mount the object, the aperture will be equally
reduced thereon in both cases. This has been shown years ago.
That the mere fusing by a refractive medium of the thinner or im-
mersion lens and cover into one, whose combined thickness barely
exceeds that of the dry lens and cover together, will be the means
of collecting a greater angle of rays from the object, is a fallacy
that must be obvious, even though my friend in Egypt, the great
Ptolemy, is now brought up as evidence against me; and whether
the object is mounted in balsam or not—I challenge Dr. Pigott, or
anyone, to get, through the object-glass with the immersion front,
a greater angle, or any portion of the extraneous rays that would
in the other case be totally reflected, as no object-glass can collect
image-forming rays beyond this limit.

IT now leave it to impartial observers to consider my objections.
I have nothing more to say concerning the immersion lens, and in
this particular the controversy with Dr. Pigott must end—if only
for the tone last assumed—that of mutilated quotations, imputed
“ personalities” ? want of “refinement,” &c. I might rebut these
insinuations by referring to the November number of this Journal
for some expressions, first emanating from himself.

I trust that I have not hitherto tried the patience of the kind
readers of this Journal. It is not my forte to write on any but
practical subjects, and in my last I gave the marginal rays traced
through an entire object-glass. Little or nothing of this kind has
been previously published. I expect shortly to be able to carry out
some experiments that I have in view, and to give another illustra-
tion, I hope to better purpose.

VII.—Nobert’s Nineteenth Band and its Observers.
By Cuartes SToppEr.

J. J. Woopwarp, Assistant-Surgeon and Brevet Lieut.-Colonel
U.S. Army, having, in a letter published in this Journal in the
August issue, affirmed his disbelief in the fact claimed by myself
and Mr. R. C. Greenleaf, of the resolution of the lines of the 19th
band of the Nobert test-plate, and his disbelief that I ever saw the
lines with the instruments named, I wish to make a rejoinder which
shall close the discussion on my part in regard to that matter.

Dr. Woodward writes, that “if Messrs. Stodder and Greenleaf’s
original claims were really well founded, they certaimly ante-dated
mine.” TI have already stated (this Journal, May, 1870) that our
original claim rests on our belief, no one else having seen the reso-
lution with the instrument then used. But in my letter I then

and its Observers. 119

claimed, and not for the first time, to have ante-dated Dr. W.’s
claims nearly a year, independent of the original claim of 1867;
and I now repeat my claim, that I and others repeatedly saw the
true lines of the 19th band with several of Tolles’ objectives (no
one of them being of so high a power as a 7/;th) previous to the
time that they were seen by him, after all due consideration of
his reasons for disbelieving me.

Dr. Woodward’s reason for refusing belief in my claim is this:
“Tn my judgment it cannot be said that one of the bands is resolved,
unless the lines are shown in such a manner that they can be cor-
rectly counted from one edge of the band to the other.” This
sentence contains the whole gist of the matter. (It will be in-
teresting hereafter to examine the evidence offered that Dr. W.
has himself performed that feat.) Dr. Woodward here assumes
that “his judgment” is conclusive and sufficient, and that that
settles the matter; that all who dissent from that “judgment”
must be in error. It is certainly a short method of settling dis-
puted questions, but a method that is not generally accepted. I
acknowledge that Dr. Woodward has obtained a high reputation as
a microscopist, that his instruments, apparatus, and facilities for
observing are of a high order, having almost at his command the
purse of the United States; that the photographs executed by him,
or under his direction, are, many of them, of surpassing excellence ;
yet I cannot admit that his “judgment” is sufficient authority, or
competent to establish the law for the microscopical world against
the “judgment” of other experts.

Mr. W. S. Sulivant says,* “a portion only of the width [of a
band] can be brought into exact focus at once; if that portion,
however, is measured, and its lines resolved under suitable ampli-
fication, the data are obtained for the solution of the problem.”
Mr. Sulivant’s authority on this question is second to none: the
method he requires has been repeatedly applied to the resolution
with Tolles’ objectives, but I did not deem it of importance enough
to mention. I have conferred with numerous experts on this matter.
Dr. Woodward’s law is generally rejected. That ought to suffice ;
but as Dr. Woodward has produced one “ witness” to support his
“judgment,” before I close I propose to introduce some on my
side.

Dr. Woodward makes some trite observations on the fact “ that
_ objectives of inadequate defining power can easily be made to show”
spurious linés—a fact to be noticed by all novices, but which it was
hardly worth while to repeat to me, as Mr. Greenleaf and myself
were perfectly familiar with the fact, having worked on the Nobert
plates for years, and resolved the equivalent of the 15th band with
a Tolley’ 1th in the year (I think) 1865. Dr. W. might have

* “American Journ. of Science,’ vol. xlvi., p. 350, and also in letter to me.

VOL. V. K

120 Nobert’s Nineteenth Band

added that not only “objectives of inadequate defining power,” but
the very best will show spurious lines if they are not properly
manipulated. He says, “Now not only did Mr. Stodder in his
original paper admit that he had not counted the lines, but he fell
into a grave error on the subject of counting fine lines, which he
expresses in the following words:—‘In counting lines of such ex-
quisite fineness, either the micrometer or the stage must be moved, ”
&c. Had it occurred to me when writing that anyone could have
possibly supposed that I referred to anything except such “ exqui-
sitely fine lines” as I saw them with only 550 diameters, I might
have been a little more explicit; but as I applied the words, they
were strictly correct, and I do not retract them. I “fell into” no
“rave error”—no error whatever; and of that Dr. Woodward’s
account of his own experience is sufficient proof. He says, “On
attempting to count the lines, however, with a good cobweb micro-
meter made by Stackpole, of New York, I found myself wnable to
get beyond the 9th or 10th band, on account of the tremor commu-
nicated to the instrument when the micrometer screw was turned ! !”*
This is a full confirmation of my remarks by Dr. Woodward him-
self. I can add that Dr. Barnard, of New York, encountered the
same difficulty. I will also say, at that time neither Mr. Greenleaf
nor myself had any apparatus to assist in counting, and that then
I had never even seen a cobweb micrometer.

Dr. Woodward has been able to find one indorser of his “ judg-
ment,’ Dr. H. Hagen, of Cambridge, an eminent entomologist.
After an examination of Dr. Hagen, and finding their “judgments ”
to coincide, Dr. Woodward pronounces him to be “a competent
witness.” Dr. Hagen has published in Max Schultze’s ‘Archiv’
(second No., 1870), a paper “On American Microscopes.” In that
he relates how Mr. Tolles undertook to show him the 19th band
with an immersion 75th. Dr. Woodward renders Dr. Hagen’s
account in this way :—‘“ He showed him limes, indeed, but he was
unable to count more than forty ‘of them. Mr. Tolles himself
counted between forty and fifty of them. These counts show that
the lines in question were spurious.” Fortunately I have a copy of
the ‘Archiv.’ The correct reading of the passage is (as translated
by a German), “ An objective of +'5th in focus showed, while band
19 was in the centre of the field, the 18th, 17th, and half of the
16th bands. ‘The lines in all were well defined, but not so that
I could have counted them all. I could count about forty of the
19th, the rest blurred.” This is very different from Dr. W.’s read-
ing, which is, that the forty counted were the whole width of the
band, and consequently spurious. I am authorized to say that
Dr. Hagen has stated in conversation that he saw the true lines.
In fact, Dr. H. saw the 19th band resolved, though he does not

* ‘Quart. Journ. Mic. Science,’ Oct., 1868, p. 229.

and its Observers. 121

admit it, because he did not count all the lines. As Dr. Hagen has
been replied to,* the reply to him will answer also for Dr. W. The
position assumed by both gentlemen is absurd; for “suppose that
Nobert had ruled in the 19th band only twenty-eight lines instead
of fifty-seven, would Dr. H. say that they were not resolved because
there were no more? Or if Nobert had covered a whole inch with
the 112,000 and some odd lines, would anyone claim that all must
be seen at once? If either of these suggestions is answered in the
negative, then Dr. Hagen has himself seen the 19th band resolved
with a Tolles’ objective.” -

The evidence of the resolution of the lines is in the progressively
increasing fineness of each band, as each is successively resolved ;
and in the experience of the observer, in distinguishing the differ-
ence between diffraction, spectral, or spurious, and the true lines.

I will now introduce my witnesses, who are tolerably well known
among microscopists, so that I hope Dr. Woodward will admit their
“competency.” Iam forced as it were to this course by Dr. Wood-
ward’s persistence in advertising that he does “not believe” me.

First, a letter from Mr. Edwin Bicknell, of the Zoological
Museum, Cambridge.

CAMBRIDGE, Sept. 8, 1870.

Dzar Sir,—I desire to state that in August, 1868, I called at Mr.
Tolles’ room in Hanover Street, and while there had an opportunity
‘of viewing the test-plate of Nobert. I distinctly saw the 19th band
(if I can trust my eyes) well resolved, the lines sharp and distinct;
with no special lines, and each line of the band much narrower than
each space between the lines. While I regard counting a positive
proof of resolution (that is, true lines, not spectral lines, which can
be counted as well as photographed), I do not think it absolutely
necessary that we should doubt our eyesight until a count is made
and compared with somebody else’s count or measurement. In case
an actual count is demanded as proof of resolution, we shall have to
throw away all our supposed resolutions of Nav. rhomboides, Sur. gemma,
Pl. fasciola, and many other common test-objects, and go to the trouble
of verifying by count and measurement before we can trust our work.
Observers who can be considered “ experts” on the subject, differ as
to whether a count is actually needed, or is not needed, as proof of
resolution; it is a matter of individual judgment, and rules cannot
well be enforced. At the time of my seeing the 19th band of the
test-plate, I had no difficulty in counting a portion of the band, but
did not undertake to count the whole of it, as it would have been very
difficult, there being no resting-points for the eye; and the whole
band would have had to be counted without stopping, which with the
low power used (3th immersion) would have been impossible for me
to have done. I am, very truly yours,

Epwin Bickyetu.

* “American Naturalist’ for Sept., 1870, p. 425; and ‘Monthly Microscopical
Journal,’ November, 1870.
K 2

122 Nobert's Nineteenth Band

Boston, Sept. 30, 1870.

Dear Srr,—In reply to your note of inquiry concerning my ex-
perience with Nobert’s test-plate, I would say that I have examined
the lines and witnessed their resolution on sundry occasions.

I have seen the lines of the 19th band satisfactorily resolved with
a Powell and Lealand’s ;),th under the skilful manipulation of my
friend Dr. Woodward, at the Army Medical Museum, Washington,
D.C. I have repeatedly seen the same equally well in this city with
some of Tolles’ excellent objectives; I have one which with its immer-
sion front is a !,th that shows the true lines of the 19th band. This
is the highest power of Tolles’ make with which I have seen the lines
in question.

One year ago, at the Eleventh Triennial Exhibition of the Mas-
sachusetts Charitable Mechanic Association, the board of judges (of
which I was one) held several meetings to test the relative and
abstract merits of microscope objectives exhibited. A 5th Amician
objective made by Tolles, and owned by Mr. Bellis, of Waltham, was
on exhibition, which with a B eye-piece clearly resolved the lines of
the 19th band of Nobert’s plate, not only to my own satisfaction, but
also to the full satisfaction of others, among whom may be specified
C. K. Stevens, Esq., of this city, whose experience on this subject
has been quite extensive. It is proper here to observe that Mr.
Stevens has been an intelligent amateur microscopist for more than
twenty years, and has had large experience with Nobert’s plates. He
imported a twenty-band plate some fifteen years ago for his own use,*
and possessed the best objectives of the most renowned makers abroad
and in this country. Mr. Spencer, of Canastota, N.Y., made for him
seven first-class objectives, on orders without limiting the price. I
mention these points, merely to show that Mr. 8. is no novice, but
experienced and competent to judge, notwithstanding his modesty
and retirement has kept his name from extended publicity. As this
zpth objective was reported to have been in the hands of other micro-
scopists of justly acknowledged eminence, who placed the 16th band
“at high-water mark” in its performance, at my suggestion other com-
petent observers were invited to test its qualities. Among those
invited were Dr. B. A. Gould, ex-President of the American Associa~
tion for the Advancement of Science; Dr. Walcott Gibbs, Rumford,
Professor in Harvard College: both of these accomplished observers
stated in unequivocal terms the satisfactory manner of the work in
fully resolving the 19th band; Dr. Gould is now in South America,
but Professor Gibbs permits the use of his letter on the occasion,
which reads thus :—

Dr. Jostan Curtis, Camprinér, Oct. 18, 1869.

Dear Sir,—In accordance with your request, conveyed to me
through Mr. Stodder, I called this afternoon on Mr. Tolles. With a
jijth objective and a B eye-piece, I saw the 19th band of Nobert’s
test-plate distinctly resolved into lines without any lateral bands or
false images whatever. ... . Respectfully yours,

Watcotrtr Gress.

and its Observers. 123

Professor Gibbs did not count the lines, nor does he profess to
have counted them, but that he saw the lines separated.

Yours truly,
Mr. C. Stopper. JostaH CurRTISs.
Extracts from a letter from Dr. F. A. P. Barnard, President of
Columbia College, New York.

PRESIDENT’S Room, Sept. 27, 1870.

My pear Srr,—Since the bands of Nobert’s plate are so exceed-
ingly narrow, it seems to une, not extravagant to claim that when with
a power not ereater than a ,|;th, one portion of the breadth of one of
them is truly resolved, the whole breadth should be so likewise. If
they were four or five times as broad, I should certainly regard Colonel
Woodward’s assumption as too sweeping. On the other hand, in my
counts which I made with a filar micrometer in the spring of 1868,
and which I described to you at the time, I found it extremely difficult
to count the whole breadth of the higher bands, principally because the
manipulation of the micrometer disturbed, sooner or later, the sharpness
of the definition. I did not count the 19th band entire. My method
was this—first by means of the coarser bands used as a stage micro-
meter, to obtain the value of the revolution of the screw of the filar
micrometer with the given objective; then by bringing the higher
band into the field, to count as long as I could, and to determine the
values of the intervals between the lines counted, and thus by infer-
ence the number of lines to the inch from the reading of the screw.
I actually counted from twenty to thirty lmes—never more, I think,
than thirty. As your letter suggests, Sulivant and Wormley counted,
apparently, for the purpose of verifying Nobert’s statements in regard to
the plate, Nobert himself objected to one of Colonel Woodward’s early
photographs, that it could not represent the band which it was claimed
to represent, because the number of lines in the entire band was too
small. This is a legitimate criticism of a photograph, because the
distance between the lines of this print would not indicate the distance
between the lines ruled on the plate unless the enlargement should be
exactly known—and about that there might be some reasonable doubt
—hbut the question, whether the lines are resolved when the real
distance between them is known, is settled the moment that the
measured distance between any two such lines distinctly seen is
found to accord exactly with the real distance. When, for instance, I
found that the value by micrometer of twenty spaces on the 19th
band as counted was exactly equal to the value by the same micrometer
of ten spaces on the 9th band, I could not doubt that the 19th was
‘resolved. I-subsequently mounted the micrometer on a detached
stand, so that turning the screw should not disturb the microscope,
but my eye or my illumination failed me, and it did not improve upon
the former performance, or even do so well.

I do not wish to be quoted as absolutely dissenting from Colonel
Woodward’s proposition, but I do hold that whether or not the whole
breadth of a band is so resolved to be countable, the question whether

124 Nobert’s Nineteenth Band

any part of it is actually resolved is settled beyond doubt, when that
part has been actually counted and the distances between the lines
have been measured.

Truly yours,

Cuar.tes SToppEr. ® F. A. P. Barnarp.

It is now desirable to examine Dr. Woodward’s pretensions a
little closer. It should be known if, or not, he always requires “the
lines to be correctly counted from one edge of the band to the other”
as proof that they are seen. Dr. W. often exhibits the resolution
of the 19th band to his visitors. Does he first always count the
lines? Or does he not rather first resolve them, and then sometimes
count? If he takes the last course, then he depends on his experi-
ence in determining that the true lines are visible, and his observa-
tions are as trustworthy as mine, no more so. Two gentlemen who
have witnessed the resolution both in Washington and Boston,
agreed in saying that that in Boston was the best.

Has Dr. W. ever really “correctly counted the lines in any one
band ?” which in his “judgment” is the sene quad non.

After all that he has written it would not seem that this question
is yet to be answered, yet an analysis of his various reports and
letters shows that there may be grave doubts.

In his letter of June 18th he says, “1 supported my statement
by a count of the lines, as well as by the photographs of Dr. Curtis.”
“T thought, and still think, that Dr. Curtis’s photographs were con-
clusive evidence that I had seen the true lines, although the spurious ©
lines shown on the edges of the band prevented them from serving
for the purpose of a count. I have recently made myself another
photograph of the same band, which will perhaps serve to convince
any who are still incredulous.”

In the ‘Am. Jour. Sci.’ for September, 1869, is Dr. W.’s original
account of his first resolution of the 19th band. He writes, “I send
two prints on glass, of which the first shows the 16th, 17th, and
18th bands satisfactorily resolved. The second shows satisfactorily
the 19th band only. These pictures should be studied under a
power of from two to six diameters. In counting the lines on them
some doubt might arise, especially in the case of the 18th and 19th
bands, as to the real number of lines; for certain spurious lines
which are interference phenomena may be seen on the margin of
the bands, and it is not always easy to tell which is the last real
and which the first spurious line. A comparison of several glass
positives from different negatives with each other, and with the
bands as seen in the microscope, where a change of focus materially
aids in the determination, has led me to adopt the count above men-
tioned.” Is this “correctly counting any one band from one edge
to the other,” as in his judgment is absolutely necessary? After all

and its Observers. 125

that comparison of photographs and microscope, he adopted a count,
just the requisite number, and passes it as real.

I have copies of the photographs referred to, and I affirm that
they do not admit of a correct count. The picture of the 19th band
has over seventy lines, and it is a matter of fancy, or taste, or judg-
ment, which shall be rejected as false, and which “adopted” as true.
Anyone can “adopt” enough to leave the right number. Dr. Cur-
tis’s photographs do not give conclusive evidence that Dr. W. had
ever seen the true lines; and they are not evidence that he had not
seen them. How is it with Dr. W.’s own photograph? A copy of
that is now before me. It purports to be a picture of the 19th band
1100 diameters, and a portion enlarged to 2800 diameters. The
picture of 1100 diameters is an excellent picture of the 19th band
as I have seen it, not resolved. Examined with a lens, an approxi-
mate count can be made with difficulty. There are certainly over
sixty lines, and some of them on one edge are so coarse that they
are evidently composed of two or more of the true lines. The en-
larged portion is evidently made by stopping off on the negative
the coarse lines of one edge and some of the finer ones of the
other edge; not a difficult feat to leave the wished-for number, yet
there are paris of the enlarged picture where I and others have been
obliged to guess whether one or two lines should be counted. This
is all that Dr. Woodward has offered, that he has “counted correctly
one band from one edge to the other.” Under the circumstances,
considering the pertinacity with which Dr. Woodward has denied
the claims of all others, I feel justified in bemg “ still incredulous,”
as are many others.

Dr. Woodward has seen fit to introduce some extraneous matters
which have nothing to do with the question whether I ever resolved
the Nobert test-plate or not. As they have been published, I am
under the necessity of noticing them.

He says, “ Mr. Stodder writes with a warmth that will be best
understood when it is known that he is the Treasurer and Agent of
the Boston Optical Works, the establishment at which Mr. Tolles
produces his really excellent lenses, and that he has for some time
claimed that Mr. Tolles produces the very best lenses in the world.
I am not willing to yield to either of those gentlemen in the dis-
interestedness of my desire for the success of American opticians,
but am of the opinion that our progress will be hindered rather
than helped, if we shut our eyes to the few cases in which English
or other manufacturers excel ours.”

I copy all the above that there may be no mistake in the lan-
suage used. Dr. W., imitating his “witness,” Dr. Hagen, must
refer to my connection with the Boston Optical Works, of course
wishing his readers to infer that my opimions are governed by
interest. I have no reply to make to that.

126 Noberts Nineteenth Band

I do not know by what authority Dr. W. says that I have
made such a claim for Tolles’ lenses; I have never published any
such claim ; when I do I shall refer to Dr. Woodward's own reports
for evidence of the propriety of it; e.g. im the ‘Am. Jour. Sci.’* he
gives the results of his trials of various objectives of different powers,
from 3th to 5th, and by various makers. No one could resolve
the test-plate finer than the 15th band. This statement he repeats
in the ‘ Quar. Jour. Mic. Sci.’ for October, 1868.t In the ‘ Monthly
Mic. Jour.’} he gives the following, additional :—“ The 1th of Wales
and s!;th and jth of Powell and Lealand, all dry lenses, resolved
the 15th band, and not the 16th. An immersion 7th by Wales
resolved the ~;th band, and failed to go farther. An immersion
sith by Wales resolved the 17th band, but failed to go farther. A
Hartnack, No. 11, also resolved the 17th band, and failed to go
farther. A Tolles’ immersion 3th, recently constructed for Dr. J.
C. Rives, of this city, resolved the 14th band.” “A Tolles’ immer-
sion y>th:§ with this I was unable to see beyond the 16th band.”
Dr. W. has broached this subject—not I. I now ask Dr. W. to
name the “few cases,” or any one case, in which the lenses of
English or any other makers have excelled the performance of those
two. Did he ever see, read of, or hear of any 1th or }th objective
of any other maker that had excelled what those did in his own
hands? Iask him to reply without equivocation—yes or no—as
publicly as he has provoked the inquiry.

Dr. Woodward takes pains to say, “Mr. Stodder’s complaint
that his paper in the ‘American Naturalist’ has been ignored,
certainly cannot apply to me.” Dr. W. has made the application
himself; I did not have him in my mind when writing that pas-

* Vol. xlvi., p. 353, Nov., 1868. t P. 229. ¢ Vol. ii, p. 292.

§ Dr.Woodward and Mr.W. 8. Sulivant both say that the 3th objective referred
to is only an eighth, “ English standard.” The instrument has since been measured
by two parties, one made it a full th, the other a little less. The English
standard and the American are the same, viz. the English inch. The mistake of
those gentlemen was that they took for granted that their English objectives must
be right. On this point I will copy from Dr. W. B. Carpenter, as I suppose that
everyone has not read his book: “It may be well here to remark, that the desig-
nations given by opticians to their objectives are often far from representing their
real focal length, as estimated by that of single lenses of equivalent magnifying
power; a temptation to wnderrate them being afforded by the consideration, that if
an objective of a certain focus will show a test-object as well as another of higher
focus, the former is to be preferred. Thus it happens that what are sold as half-
inch objectives are often more nearly ;4,ths; and that what are sold as ths are not
unfrequently more nearly 1ths” (‘The Microscope.’ London. 4th ed., p. 184).

This quotation shows the practice and explains the reason for it. See also
‘Quar. Journ. Mic. Science,’ 1862 and 1863; Mr. E. Bicknell in ‘Am. Naturalist,’
1870 ; and Mr, Cross in ‘ Journ. Franklin Institute,’ Philadelphia, 1870, and repub-
lished in ‘ Monthly Mic. Journ.,’ Sept., 1870.

I am happy to say that at the recent meeting of the American Association for
the Advancement of Science, held at Troy, New York, a committee was appointed.
by the suggestion of Dr. Josiah Curtis, of Boston, to consider this subject, and to
secure, if possible, uniformity of designation at least for American objectives.

and its Observers. 127

sage; but as he has, uncalled for, entered a disclaimer, I will now
specify that he has, as I believe intentionally, ignored the claims of
Nachet, Mr. Greenleaf, and myself. On the 31st of May, 1869,
Dr. Woodward gave a lecture before the Biological and Microsco-
pical Section of the Academy of Natural Sciences of Philadelphia ;
a synopsis of the lecture is reported in the ‘ Dental Cosmos,’ Phila-
delphia, August, 1869.* When he exhibited the photographs of
the test-plate, he referred to his paper in the ‘ Microscopical
Journal’ for 1868, and is reported to have used the words: “ At
the time he published that article no microscopist had succeeded
in seeing the true lines in any of the bands in this plate beyond
the 15th.” It seems to most people that this is “ignoring,” and
something more. But the Doctor may say that he is not re-
sponsible for the report. Well, let us see something else that he
cannot deny responsibility for. About the time of the delivery
of the lecture, and before that report was issued, he published
Dr. Curtis’s photographs of the claimed resolution of the 19th
band, with two pages of letter-press explanation, a copy of which
is now before me. The last two lines read, “These pictures of the
Nobert’s test-plate are the first photographic representations of this
interesting test-object, and the true lines in the 16th, 17th, 18th,
and 19th bands were first resolved at the Army Medical Museum.”
I will here take leave of the subject.

Bosron, Mass., U.S.A., Sept. 30, 1870.

2 USGL

a 2) en

NEW BOOKS, WITH SHORT NOTICES.

A Report on the Microscopic Objects found in Cholera Evacuations.
By Timothy Richards Lewis, M.B, Printed by order of Govern-
ment. Calcutta: Office of Superintendent of Government Printing.
1870.—It is but a few years since great sensation was produced by
Hallier’s researches into the nature and cause of cholera, It was
then pretty nearly believed that the cholera-fungus was ‘really the
cause of the disease, and that by avoiding connection with this plant
the disease might be altogether avoided. But of late so much good
work has been done on the subject of cholera-causation, that the Ger-
man Professor’s ideas have been shown to be extremely vague, and to
be devoid of that care and precaution in their formation which are so
essential in all experiments relating to the question, Whence comes
cholera? We do not see that the author of the present volume had a
very difficult task to perform in exposing the error and manifest care-
lessness of Professor Hallier’s opinions. Still, it is perhaps as well
that he should have done so, for so many people are prepared to
believe anything stated on German authority, that the cholera-fungus
may have yet many supporters, even in this country. But apart
altogether from the several views which have from time to time been
put forward on the cholera-fungus subject, this work has a special
value. It is not that the author has committed himself to any view
or endeavoured to support any particular theory ; but from the cir-
cumstance that he has exposed somewhat fully the views of the fungus
theorists, and has himself more fully than anyone else gone into the
whole subject, and cultivated at considerable trouble, and with the
most careful investigation, the various fungus bodies, and so far shown
that the theories held upon the subject have really no foundation in
point of fact.

The work is somewhat unsatisfactory in design, being rather a
record of experiments than a continuous essay on the subject. Still,
it is extremely valuable from the number of microscopic drawings
(more than 100) which it contains, some of them being copies of those
of other observers, but the great majority being the results of the
author’s inquiries into the subject. We notice ‘that the powers em-
ployed are, generally speaking, very low; indeed, the highest, we
think, employed is 600 diameters. We fancy that this was an error.
Undoubtedly, with higher powers much more would have been
observed ; and we think it is to be regretted, for the work is the fullest
and, from its illustrations, the most complete on the subject. The
plan of the volume is somewhat vague, but the end is clearly attained,
and shows us that we cannot hold any of the existing theories as to the
cholera-fungus proposition. It by no means proves that cholera is not
propagated by fungi; but it shows that the present theories have in fact
no foundation. Here and there the author points out some remarkable
facts, as, for example, the development of Mucor from Penicillium; but
on the whole his inquiries are valuable but from one aspect, that of the
cholera-theories. We thank Dr. Lewis for the publication of this work,

—

NEW BOOKS, WITH SHORT NOTICES. 129

for while it has involved immense labour upon the author, it tends to
prevent us from assuming as a certainty that cholera is due to the fungus
described by Hallier ; and that cannot be held in the History of Science
to be a matter of no importance. Dr. Lewis, we believe, proposes to
continue his researches, and we hope he may, for good as his present
work is, we may even expect a better labour in the future.

“On a Searcher for Aplanatic Images applied to Microscopes, and
its Effects in increasing Power and improving Definition. By G. W.
Royston-Pigott, M.A., M.D., Cantab., M.R.C.P., F.C.P.S., F.R.AS.,
formerly Fellow of St. Peter’s College, Cambridge. Communicated
by Professor Stokes, Sec. R.S.”’—A paper on a new instrument having
recently appeared in the ‘ Philosophical Transactions,’ and been re-
printed from them for private circulation, we think some notice of it
will not be unwelcome to our Fellows.

The writer seems to have long felt, with other microscopists, that
something remained to be done—first, in overcoming the great incon-
venience attending the use of very deep eye-pieces, deep objectives
dangerously close to the covered object; and next, in adding further
corrections, in addition to those of the screw-collar for different thick-
nesses of glass cover. In these principal points he appears to have
succeeded.

The traverse of a system of adjustable lenses between the fixed
eye-piece and objective produces some remarkable changes in the
definition, better or worse, according to the skill of the operator, and
admitting a much wider range- of chromatic and spherical correc-
tions than can possibly be obtained by merely separating the objective
lenses by means of the screw-collar. The author of this paper states
(p. 598) :-—

“Using additional compensating lenses to gain increase of power,
intermediately placed between eye-piece and objective, the finest defi-
nition is obtained when each of the three sets, viz. lenses, observing
and image-objective, are similarly, though slightly over-corrected, as
compared with a standard defining distance of 9 inches.*

“ Although a fine definition seemed now attainable by means of
supplementary compensating lenses, if judiciously introducing ba-

* “Tt is convenient to define the aberration to be positive or negative, or the
lens to be over or under corrected, by the simple fact that an ordinary lens causes
the excentrical rays to cross the axis at a point nearer the centre of the lens than
the centrical rays, in which case, and in all analogous cases, it may be said that
the lens is under-corrected and afflicted with a negative aberration. All the best
objectives are now constructed on the principle of having the posterior sets over-
corrected and the anterior under-corrected so skilfully as to destroy by opposite
errors nearly the residuary aberration; but the opinion may be hazarded that
future combinations will yet be found which will completely throw into the shade
the present powers of the microscope, when, perhaps, we shall be in a better

position to attempt to determine the microscopical features of molecular life, at
present probably beyond its grasp, as no single particle so small as the ;51,,th
of an inch in diameter can be clearly defined, if isolated, until residuary error is
very much more reduced.

“Tt is to be regretted that the precise nature of the marvellous combinations
invented by Professor Amici for objectives remains unknown. As one of the
Jurors in the Paris Exposition, his microscope necessarily remained both uncele-
brated and unelucidated in the Reports.

130 NEW BOOKS, WITH SHORT NOTICES.

lancing compensations, yet their practical adjustments were innumer-
able and tediously accomplished.* At this stage of the research,
frequent consideration of the well-known optical equations for a
vanishing aberration fortunately suggested to me the idea of searching
the axis mechanically for aplanatic foci. In reference to these equa-
tions, which would be out of place here, it has been observed by Mr.
Parkinson, F.R.S.,t ‘If the aberration for rays parallel at incidence
of a compound lens of given focal length, consisting of several thin
lenses in contact, be examined, it will consist of a series of terms
similar to that in Art. 129, one term for each lens, and the condition
that the aberration shall vanish will lead to an equation involving
more than one unknown quantity, and consequently admitting an un-
limited number of solutions.’ ”

Mr. Lister, whose paper in the ‘ Phil. Trans.,’ 1830, accomplished so
much for the development of the modern microscope, though no mathe-
matician, ascertained the positions of two aplanatic foci, the longer and
shorter ; but it would appear from this research that a great number
of aplanatic foci exist at different points of the axis. And that whilst
many objectives refuse to define well at the standard distance a varia-
tion of the distance, as attained by the new instrument, the aplanatic
searcher, may be rewarded with success; especially when it is con-
sidered that the searcher automatically changes its own aberrations by
a simple traverse. One of the advantages attending its use is thus
described :—

“When it is desirable to view an object through a very thick
refracting medium, the searcher is brought as close as possible to the
objective, which action lengthens the focus of the objective; and the
same thing is necessary when the observer wishes to throw the eidola
of an upper structure above and away from the true image of the lower
but contiguous stratum—as when the lower beads of the Podura are
required, or when it is required to give additional negative aberration
to an objective too positively corrected in which the front glasses are
already in dangerous proximity.”

“On the contrary, when the searcher is traversed the opposite
way the objective lenses require to be brought nearer together; the
instrument is then more adapted for viewing objects or particles lying

* “Turing 1865-1869 many experiments were tried with complete objectives
and various parts of them, either over or under corrected, by means of a sliding
tube carrying them and fitting into the ‘draw-tube.’

“Professor Listing, of Bonn, more recently has in two papers confirmed the
value of this method of amplification quite independently. Nachr. d. hgl. Gesell.
der Wissen, 1869, No. 1, and Poggend Annalen, 1869, t. 16, p. 467 (‘ Nature,’
Jan. 27, 1870).

“Tn the first he recommended an inverted Huyghenian eye-piece, and in the
second intermediate achromatic lenses.

“ As regards intermediate lenses, the writer has ascertained (Noy. 1870) that
Dr. Goring (‘Micrographia,’ ed. 1837) has anticipated both these methods.—
Note added Noy. 1870.’

+ This term “searching the axis” was early employed by Dr. Pigott, viz. in
his first essay, received May 21, 1869. He says, “A search for the real focus or
best image should not be neglected along the axis of the instrument ” (p. 297, Dec.
No. 1869).

} “ Griffin’s ‘ Optics,” by Parkinson, p. 122,”

NEW BOOKS, WITH SHORT NOTICES. 131

in the upper plane of a complex structure, throwing the eidola of the
lower layer below that layer itself, and so leaving the upper stratum
less disguised by the false images of the lower.”

“Tn intermediate cases, where greater penetration or focal perspec-
tive is required, with a thin glass cover, the objective lenses must be
proportionately separated by an increased interval, the searcher being
traversed towards the objective ; and in general confused images of both
upper and lower strata can be obtained by opposite arrangements.*

“ A very interesting refinement upon the corrections for chromatic
effects may be accomplished by gradually traversing either way both
searching and objective lenses and closely watching the effect.

“The most brilliant definition is generally obtained when the
searcher (a little more over-corrected) is used as close to the objective
as possible. 3

“'The over-correction of the searcher is increased by separating its
component lenses according to the divisions upon the sliding tubes of
the searcher. ©

“The change in the general aberration is shown by the divided
index of the milled head actuating the movement of the searcher.

“The power obtained is in general from two and a half to four
times greater than that given with the third eye-piece C of 1-inch
focal length: with a very fine eighth of Messrs. Powell and Lealand’s
new construction, a clear and satisfactory definition of the beading of
the Pleurosigma formosum was exhibited to them, by means of the
aplanatic searcher, at a power estimated at 4000 diameters.

“This paper, perhaps, will hardly be complete if I omit to add,
that the instrument will be most effectively employed by considering
it as a conjugate portion or integral part of the objective itself, in
which the minute traversing adjustment of the objective lenses finds
its counterpart in: the more extended and therefore more delicate
adjusting traverse of the searcher itself. So that, in short, during
minute microscopical research each adjustment should be intelligently
applied, according to the nature of the research in hand. The indica-
tions of the one adjustment should be employed to verify those of the
other. Correlative movements by the aid of the searcher may intro-
duce aplanatic images, whilst a violation of their correlation will
exhibit deformity.”

It would appear from this paper, that the very finest definition
and working power is to be sought rather in the use of comparatively
low objectives, such as the 3th, }th, and 1th. In a note the author
states (p. 602) :—* That a Wray 1th made expressly, admitted of as great
amplification as an ordinary th. In fact, these researches appear to
point decisively to greater advantages to be expected from raising the

* “Such as separating the objective lenses and traversing the searcher
farther from them.

+ “With a ‘ Kelner’ two-thirds of an inch focal length, a very clear, very large
and flat field is presented to the eye, notwithstanding the increased power with
the searcher. A 13-inch objective by Ross was used generally for a condensing
illuminating apparatus more or less stopped off. “The usual power of the 1th
with a C eye-piece is 800; a power of 4000 is given by an eye-piece of one- fifth of
an inch focal length.”

132 NEW BOOKS, WITH SHORT NOTICES.

quality of the lower objectives rather than deepening focal length.
Observers are more numerous every year who prefer the 1th to the
szth and »yth.”

“‘ APPENDIX.

“The law of displacement followed by the final focal image corre-
sponding to a minute displacement of the internal lenses of a complex
objective, the front lenses or facet remaining fixed, possesses some
interest and may thus be expressed :—

“Tet F be the distance of the final focal image when the objective
lenses are closed together.

“F169 F its distance when the front sets of the objective are dis-
placed by a quantity 0 a.

“Then it will be found if f, be the distance of the virtual image
conjugate with the object as formed by the front set of lenses,

Oa RE ere Lise i?

and consequently every slight change of the screw-collar of an adjust-
ing objective produces comparatively a very large displacement in the
final focal image, and therefore of the traversing image searcher; so
that the searcher-traverse represents a movement conjugate with the
objective index. Again, since this traverse towards the objective
encounters rays of increasing divergence, an increasing breadth of
pencil is encountered by the lenses of the searcher, and its own pecu-
liar aberration receives an instantaneous increase, which introduces an
important new element in definition; it having been observed that the
glasses must be very gradually over-corrected as the image is formed
nearer the objective.”

The rage for diatom resolving microscopes requiring an enormous
angular aperture will now probably be abated in favour of instruments
long preferred by working naturalists, to whom a just display of an
object in relation to its parts, by penetration or depth of focal per-
spective, with a working distance between the object and objective
sufficiently roomy to admit manipulation, are conditions indispensable
to organic structural research. We cannot but think Dr. Royston-
Pigott’s invention a valuable one, even if it does nothing more than
substitute low eye-pieces for deep ones, and enable the half-inch power
to work at a greater distance, with a power of 800. We observe with
pleasure the paper was communicated by Professor Stokes, whose name
has so long been associated with advanced optical science.

We think it should be here intimated that Dr. Royston-Pigott
has tried a variety of convex and concave lenses for searchers. The
“ Barlow” achromatic concave lens, when not made too deep, produces
some good effects, gives an inverted image instead of erect, but also
often displays a “central ghost,’ and is incapable of producing the
automatic and differential adjustments so much prized in transcen-
dental definition. There will doubtless be many cheap imitations,
which, it may be feared, will only caricature the properly-constructed
instrument, which must be regarded as a new aid to microscopical
research.

( 183 )

PROGRESS OF MICROSCOPICAL SCIENCE.

Metamorphoses of Siredon Mexicanus.—Professor E. D. Cope has a
short but interesting paper on this subject in Silliman’s ‘ American
Journal’ for February. He states that Professor Baird was well
acquainted with the metamorphoses of this group at the time that they
were observed in the Jardin des Plantes. Even so early as 1847, in
his essay, he regarded several species as larve. He, after some general
observations, records his belief that S. Mexicanus will be found to
undergo metamorphoses sometimes, but he states that he has not
observed it.

Insects in Deep Salt-water.—Mr. A. 8. Packard, jun., gives in the
above-named journal a notice of certain insects obtained from deep sea-
water by Professor Verrill. Some of them are microscopic, and it is
puzzling enough to imagine how air-breathing animals obtain air at
20 fathoms depth in salt water. The author says the present species
was dredged by Professor Verrill in 20 fathoms, on Clark’s Ledge, in
Eastport Harbour. It was found (four or five specimens, young and
adult) “on hydroids,” &c. It will be an interesting point to determine
whether, like the other species of the genus, it also lives in the earlier
or even in the adult state among the giils of Lamellibranchs, and also
whether it lives between tide marks, thus agreeing with the distribu-
tion of Chironomus oceanicus, At any rate we have here an insect and
a mite breathing by tracheex, and extracting the oxygen from the water
at the great depth of 120 feet, and, in the case of the dipterous larva,
with no apparent variation from specimens living at low-water mark.
In this connection he notices the fact that they have on the New England
and Labrador shores several species of mites of the family Trom-
bidide, which run over seaweeds and live under stones between tide
marks, and he has observed similar species at Beaufort, N.C., and
Key West, Florida. As regards the distribution of the species of
brine insects, several questions of interest arise. How are we to
account for the origin of the Ephydra halophila in such prodigious
quantities in the vats of the Equality Salt Works of Illinois, a locality
remote from salt lakes and the ocean shores? Are the brine species
of the Salt Lakes of Utah and California remnants of an oceanic
fauna and of the tertiary period, or are they of recent and local
origin? Have these brine insects acquired their singular tastes
within a recent geological period (say the Quaternary), having lived
at first as do their allied species, in foul fresh-water, or amid decaying
matter in damp localities? Before these and other questions can be
answered, we must have analyses of the waters, and a review of the
European literature on the subject, and larger collections of brine
animals from our own country.

Infusoria and Sponges.—It does not at first appear that there is a
relationship of an intimate nature between these two. Professor H.
James-Clark, of the Kentucky University, appears to think differently
however, and imagines that there is an intimate relationship between

134 PROGRESS OF MICROSCOPICAL SCIENCE.

the two classes. He gives the following account of an intermediate
form. He says that in Schultze’s ‘ Archiv. fiir Mikroskopische Ana-
tomie,’ * Cienkowsky describes, under the name Phalansterium, a genus
which consists of monad-like bodies with a flagellum and a projecting
collar like those of Codosiga, Salpingaca and Leucosolenia. Of the two
species which he illustrates, one (P. consociatum) has monads enveloped
in a broad funnel-shaped, slimy sheath, and these sheaths are closely
packed side by side, radiatingly, so as to form a shield-like or a hemi-
spherical mass. This comes nearest to the Salpingeca. The other
species (P. intestinum) possesses similar monads, but they are im-
bedded basally in a gelatinous, intestiniform mass of slime (Schleim),
“ with their vibrating lashes extending in every direction” about the
cylindrical colony. Originally each monad is endowed with a sepa-
rate slime-sheath ; but eventually these all are fused together into one
common mass. Beyond this, to make a true Sponge we need but the
presence of spicule, and open interspaces in the slimy mass, between
the monads, leading to one common cavity. Introvert the layer of
monads, and we produce the desired effect without doing violence to
their relative positions. It is a mere matter of proportions, just as the
inverted cyathiform rose-hip is none the less an ovariferous disk than
the globular receptacle of the strawberry.

Striated Muscular Fibre in Gasteropoda.—Mr. W. H. Dall (of
America) says that in studying the radula of a species of Acmcea
(probably A. Borneénsis, Rve), obtained by Professor A. §. Bickmore

at Amboyna, he noticed, on placing the structure under a power of-

100 diameters, that certain of the muscular fibres which adhered to it
when torn from the buccal mass, had a different appearance from the
others. On increasing the power to some 800 diameters, it was at
once evident that the different aspect of these fasciculi was caused by
fine, but clearly defined, transverse striation. Suspecting that it was
an optical delusion, caused by a very regular arrangement of the
nuclei of the fibres, he subjected the muscle to various tests and to
still higher magnifying powers. He also introduced under the same
glass, some of the voluntary dorsal muscles of a small crustacean, for
comparison. The structure of the ultimate fibres in both appeared to
be similar. These seemed to be composed of a homogeneous tube or
cylindrical band of translucent matter, with nuclei interspersed at
irregular intervals. In neither was there any appearance of separa-
tion into transverse disks, as is seen in the striated muscles of verte-
brates. That the striated appearance was not due to contraction and
folding of the muscle was evident upon taking a side view of one of
the fibres, when the striz on each side, as well as the intervening
elevations, were seen to correspond exactly to each other. The only
perceptible differences between the muscles of the crustacean and the
striated muscles of the mollusk, appeared to be that the latter were
much more finely striated ; the strie being six to eight times as nume-
rous as in the former, in the same space. No difference between the
striated and non-striated muscles of the Acmcea could be observed,

* Bd. vi. 4, 1870.

PROGRESS OF MICROSCOPICAL SCIENCE. 135

except in the fact of the striation. In both the nuclei were irregu-
larly distributed. The appearance of the striated fibre reminded one
of a string of rhombic heads, which bore no relation to the position of
the true nuclei. The striated fibres appeared, after a careful dissec-
tion of the parts in a number of specimens, to be the retractors of the
radula; they were longer and in narrower bands than the non-striated
fibres, and comparatively much fewer in number. The striation was
most evident towards the middle of the fibres, and became evanescent
towards their extremities.

Are the Brachiopods Annelids ?—Mr. Edward 8. Morse replies at
some length to the views of Mr. Wm. H. Dall on the above subject,
and as his remarks extend to some length, but are of great interest,
we give them bodily to our readers. “ Mr. Dall says that the ‘ utmost
impartiality’ should be used in the discussion, and ‘due consideration
should be given to the facts, &c. This ‘utmost impartiality’ is
illustrated, by passing over in absolute silence, not only all my refer-
ences to the limited knowledge we possess of the embryology of the
Brachiopods as shown by Lacaze-Duthiers, but the dorsal and ventral
plates—the serial arrangement above and below of setz, and even the
gill lamine in Lingula, as first recognized by Savigny in the Annelids
—the bi-lobed lophophore—the cephalic collar—the thin and mus-
cular visceral walls—the singular results obtained by Gratiolet in
the chemical analysis of the shell of Lingula anatina—the presence of
the cecal prolongations of the mantle, and their relations to the poren-
kanale in the Annelids—and, above all, the remarkable existence of
one or more pairs of segmental organs, in form, character, and functions
like the segmental organs of the Annelids, the first feature that led
me to regard the Brachiopods as Annelids six months before I ever
saw living Lingule. All these points are passed over in the ‘ utmost
impartiality’ of silence. Overlooking with the same impartiality my
statement that the Brachiopods presented a comprehensive type, and
comprised certain crustacean characters, he neglects to mention the
winter egg of the Polyzoa, and similar features in the lower Crustacea,
and we might add similar features in certain Rotifers, now admitted to
be worms. So also the presence of striated muscular fibre in certain
muscles of the Brachiopoda, their absence in the Mollusca (?), and
their presence as one of the prominent characters in Crustacea. He
gives us, however, Clark’s definition of the Mollusca, which comprise
the characters of the branch as then understood, which includes, of
course, the Tunicata, Polyzoa, and Brachiopoda. In defining the
Vermes, with the same impartiality, reference is made only to those
Vermes in which the body is made up of a repetition of similar parts,
overlooking entirely the unsegmental Vermes which comprise a large
. proportion of the class; nor is reference made to the remarkable
cephalization of many Annelids, where the posterior portion of the
body has been called a caudal appendage, being without bristles. In
some, the thoracic rings, few in number, have a wide flaring mem-
brane running continuously along each side (Protula). We leave others
to judge of his conclusions respecting the character of the sete, as
also his startling homology of the peduncle of Lingula, and the

VOL. V. L

136 PROGRESS OF MICROSCOPICAL SCIENCE.

siphonal tubes of a clam (!), and call attention to his statement, that
because the sete are not found the entire length of the peduncle,
therefore they are by no.means ‘identical’ with those of the worms.
This will be a new idea to naturalists, that the confinement of appen-
dages to limited portions of the body forbids all homology with those
in which the appendages run the entire length. It indicates also that
Mr. Dall believes that all Cheetopods have sete from head to tail. He
states as a grave objection that the Brachiopods are invariably attached
by muscles to a bivalve shell. In the same breath he should have
added that worms are also invariably attached to a bivalve or multi-
valve shell, whether it be the scuta of Sternaspis, the oval plates of
Lepidonotus, or the hardened integuments of others. He lays great
stress on the presence of bristles in Chiton, as if that group were the
very embodiment of the Molluscan type; but with the same impar-
tiality he neglects to mention its embryology, so remarkably articulate,
as shown by Lovén, its dorsal vessel, the double and forward opening
of the oviducts, the anus terminal, and other features, so remarkably
articulate as to induce De Blainville to recognize their affinities with
the Annelids, to prompt Milne-Edwards to call them a Satellite
group, and to cause Jeffries to liken them, in their different stages,
to ‘Isopods, tiny trilobites, Onisci and Aphrodita.’ In mentioning
my anatomical drawing of various Brachiopods, he says, ‘Some of
them taken from life;’ he should have said, ‘Most of them taken
from life. In concluding his paper, he refers to drawings in my
collection of a ‘singular sipunculoid worm, ‘and appears from them
to have an anterior termination to the intestine, thus forming a notable
exception to the general rule among worms.’ The drawing to which
he refers is the common sipunculoid worm of the coast. Phascolosoma,
Sipunculus, and its allies claim it as a right to have an anterior termi-
nation to the intestine, a fact known to everyone who ever made them
a study. Finally, in his comparisons, with the exception of Chiton,
he confines himself to and only points out a few of the many relation-
ships between the Brachiopods and Polyzoa and Tunicates, admitted
by all. Now, since Leuckart, Gegenbaur, Haeckel, and other eminent
naturalists of Europe, have seen conclusive reasons to remove the
Polyzoa and Tunicates entirely from the Mollusca, and place them
among the Vermes, it seems that Mr. Dall’s first task should be to
whip these back to the Mollusca before commencing with the Bra-
chiopods.”

Linneus, the Originator of the Hypothesis of the Derivation of Species.
—Ludwig von Hohenbithel-Heufler contributes an article to the ‘ Bo-
tanische Zeitung’ for September 9, 1870, in which he claims for Lin-
neus the origination of the theory of the derivation of species, founding
the claim upon the paragraphs which Linnzus appended to the sixth
edition of his ‘Genera Plantarum, published in 1764, viz. :—

1. “Creator T. O. in primordio vestiit Vegetabile Medullare
principiis constitutivis diversi Corticalis, unde tot difformia
individua, quot Ordines Naturales, prognata.

2. “ Classicas has (1) plantas Omnipotens miscuit inter se, unde
tot Genera ordinum, quot inde plante.

*
~~ ee

NOTES AND MEMORANDA. 137

3. “ Genericas has (2) miscuit Natura, unde tot species congeneres,
quot hodie existunt.

4. “Species has (3) miscuit Casus, unde totidem, quot passim
occurrunt, Varietates.

5. “Suadent hee (1-4) Creatoris leges a simplicibus ad composita.
Nature leges generationis in hybridis. Hominis leges ex
observatis a posteriori.”

Whatever meaning be put upon these somewhat enigmatical pro-
positions, they certainly show that Linnzus (as a naturalist of his
turn of mind was not unlikely to do) had thought of a derivative
origin of species as not improbable, and had formed some idea of an
hypothesis concerning it,—perhaps as definite as his idea of natural
orders,—a problem he could suggest rather than solve. And it is
interesting to note the scale of operating powers,—Chance sufficing
for the production of varieties, Nature for genera, the Omnipotent
directly for the mightier work of producing orders. But in a subse-
quent number of the same journal (November, 1870), the veteran
Professor Von Mohl maintains that Linneus did not hold the theory
of the origin of species which is now becoming so general.

NOTES AND MEMORANDA.

Alteration of Day of Meeting of the Society.—The next meeting
of the Society will take place on the first day of March. In future,
the meetings will be held on the first, instead of the second, Wednesday
in the month.

Mr. Lee and the Croydon Microscopical Club.—Mr. Henry Lee,
the President and originator of the Croydon Microscopical Club,
delivered his annual address before a large and important meeting, on
Wednesday, the 18th day of January last. After the usual business had
been gone through, Mr. Lee addressed the members at some length.
After dwelling upon the advantages of such clubs, upon the field
that lay before them, and upon the success of the Society’s soirée,
he concluded as follows :— And, now, I come to a point of great
importance in its influence upon the usefulness of our studies to our-
selves and others: I refer to the systematizing of our work. I am
satisfied with what has been done during our first year, but it is time
that each of us began, in conjunction with others of similar taste, to
follow up with a distinct purpose some particular subject. The pur-
pose should be the more complete knowledge of our local natural
history ; and the subjects which I would especially indicate to you as
not difficult, are entomology, botany, and microscopic paleontology
and pond-life. On a former occasion I communicated to you my
friend Mr. Wilson Saunders’s suggestion that we should unite with the
Holmesdale Club at Reigate in the botanical section; and I shall
shortly ask those who are interested and able to help in the four

L 2

138 CORRESPONDENCE.

subjects I have named, to confer with me respecting the organization
of co-operative work upon them. I have seen so much skill and in-
genuity displayed by many of our members in preparing and mounting
objects, and so much latent talent in this direction, that I have deter-
mined to offer a prize, to be presented at our next annual meeting, for
the best series of five dozen mounted objects. The rarity, novelty,
and scientific value of the specimens, difficulty of preparation, and
neatness of manipulation will be duly considered. The competitors
must be amateurs and members of the club, the judges will be two
members of the council of the Royal Microscopical Society, and the
prize will be a cabinet designed by myself to contain all the necessary
apparatus for the mounting of microscopic objects, and of the value
of 51. I conclude with the assurance of the happiness I have expe-
rienced in associating with you all during the past year, and with the
hope that, encouraged and assisted by our fellow-members, and
stimulated by their approbation and example, we may be able, during
that which is to come, to maintain and increase the attractiveness and
usefulness of our club.

How to Mount Objects.—A good paper on this subject appears in
the ‘Journal of the Quekett Club’ (January, 1871). It is by Mr.
D. E. Goddard. It is too long for abstract, but we refer to it, as
some of our younger readers may find parts of it extremely beneficial.
In 1863, Mr. Goddard described, in the ‘ Quarterly Journal of Micro-
scopical Science,’ a peculiar table for mounting objects, which has also
an interest for the student in connection with the present subject.

Spontaneous Generation.— Dr. Bastian’s ideas are well opposed
by Mr. T. B. Lowne in a paper “On Spontaneous Generation,” pub-
lished in the ‘ Journal of the Quekett Club.’

A Neutral-Tint Selenite Stage.— Mr. W. Ackland describes, in
the ‘ Journal of the Quekett Club’ for January, a useful form of
selenite stage, which gives a tint between the violet of the second,
and indigo of the third, wave. He shows how this can be done, and
describes some excellent results.

CORRESPONDENCE.

A Commirter ror Examination oF OBJECTIVES.
To the Editor of the ‘Monthly Microscopical Journal.

2, LANSDOWNE CRESCENT, W.
Dear Sir,—It would give me great pleasure to hear of a Com-
mittee being formed for the Examination of the relative qualities and
powers of English and Foreign Microscopic Objectives, whether dry
or immersed.
[In order to prevent all suspicion of prejudice, it would perhaps be
advisable for each maker to mount the glasses in similar plane cylin-

— =.

CORRESPONDENCE. - 139

drical forms with screw-collars, the pattern of which should be pre-
viously assigned, and identification secured either by a small engraved
motto or high numbers. The motto with the maker’s name to be en-
closed in a sealed envelope, to be opened by the committee after its
final award. The definition to be tried both with full and reduced
apertures, with long and short tubes and approved eye-pieces (deep),
C, D, E, F of ascertained focal length. |

1) For Resolution.
{3} For Penetration or depth of focus.

3) For Magnifying Power.

4) For Spherical and Chromatic Aberration.
5) For Angular Aperture.

Tilumination to be entirely centrical through a 14-inch objective
condenser, limited to 10° aperture, used obliquely or directly.

I cannot but think that some such scheme would greatly benefit
microscopical science, and settle some necessary axioms about which we
are very much at sea at the present moment.

I am yours, very faithfully,

G. W. Royston-Picort.
P.S.—I propose at the next meeting to exhibit and illustrate the

little instruments alluded to in this number, should the President
approve of this suggestion.

EncuisH Microscorpists.

To the Editor of the * Monthly Micrescopical Journal,

4, Sr. Martin’s Pxace, Feb. 16, 1871.

Sir,—You have done me the honour of indirectly referring, in
your January number, to certain experiments of mine with infusions
of milk. If you had not done so, I should not have noticed the
criticisms of the anonymous writer in the American journal from
which you quote.

I quite agree with my critic that ameba is “an object about the
nature of which very little is known,” but I trust I am not so ignorant
as not to know ameba when it shows itself under the microscope. Nor
is it likely that I should mistake for infusoria the so-called oil globules
of milk, the movement of which I have watched too often to be thus
deceived. It appears to me to be very objectionable for writers to
thus broadly, and in reality without the slightest ground, endeavour
to throw discredit on the observations of others. Nor is it good
taste, to say the least, to assume that all observations but those which
agree with the notions of American microscopists are made with
‘‘ inferior instruments,” as compared with Mr. Holman’s “ good
objective.” The italics are not mine.

I am, sir, yours obediently,

C. SrantbAND WAKE.

( 140 )

PROCEEDINGS OF SOCIETIES.”

Royat MicroscopicaAL Sociery.

Kine’s Cotuece, February 8, 1871.

The Annual General Meeting of the Society was held; James
Glaisher, Esq., F.R.S., V.P., in the chair.

The minutes of the last meeting were read by the Secretary.

Mr. Ingpen said that before the confirmation of the minutes he
would move that the minute in reference to the nomination paper
sent in by Mr. Ince be expunged. By the 44th bye-law he believed
that nomination paper was informal, inasmuch as it was not signed by
three or more Fellows before it was brought before the meeting. If it
had been brought before the notice of the meeting for the purpose of
having the names of any two Fellows added to it, by the 44th bye-law
it should have remained open until the close of the meeting. Mr.
Ingpen cited the bye-law, and said it seemed to him that as the notice
stood upon the minutes it was nothing more nor less than an intended
slur upon one of the Society’s oldest members. On this account he
moved that it be expunged from the minutes.

Mr. J. Charters White seconded the motion.

The Secretary explained that no Fellow was absolutely interdicted
by the bye-laws from bringing forward a motion without notice, except
one for altering any bye-law. The notice was no doubt informal,
but out of courtesy to the gentleman who handed it in, the Chairman
put it to the meeting.

The Chairman was willing to take some blame to himself for
reading from the chair a notice which was not in strict accordance
with the rules of the Society; but the paper having been put into his
hands after he had taken the chair, out of courtesy to the gentleman
who proposed the motion he had read it. He apologized for the
infringement of the rules in the manner which had been indicated.

The ‘proposition was then put to the meeting that the minute
relating to the nomination paper handed in by Mr. Ince should be
expunged from the records of the Society, and agreed to by a large
majority.

The list of donations was then read, and the thanks of the meeting
presented to the respective donors.

Mr. Lee said some months ago he had the pleasure of mentioning
the fact that a friend had authorized him to spend 201. in the purchase
of objects for the Society’s cabinet. He had had it in contemplation
to purchase Mr. Carter’s bone sections, but Mr. Joseph Beck’s hand-
some present had forestalled his purpose. Subsequently some objects

* Secretaries of Societies will greatly oblige us by writing their reports legibly
—especially by printing the technical terms thus : H y dra—and by “ underlining ”
words, such as specific names, which must be printed in italics. They will thus
secure accuracy and enhance the value of their proceedings.—Ep. M. M. J.

ee

PROCEEDINGS OF SOCIETIES. 141

came into his possession collected by Mrs. Clarke, of Whitby, and
he now had to announce that 210 specimens of the Marine Alge of
Whitby had been presented by Mr. H. Whitling as a first instalment.

A special vote of thanks was given to Mr. Whitling for this
valuable donation, and thanks to Mr. Lee, through whom the present
had been made.

The President then appointed Messrs. Hilton and Suffolk to act
as Scrutineers of the ballot for the election of the officers of the
Society for the ensuing year.

The Chairman announced that he had received a letter from Dr.
Royston-Pigott stating {that an error had been inadvertently made in
the engraving of the woodcut on page 66 of the Journal.* The error
would be rectified in the next number.

The Secretary then read the financial statement for the year.

The Secretaries announced that the lamented illness and death of
the late President had prevented his taking any part in the preparation
of the Annual Address. Under these circumstances they had com-
piled an account of the Society’s operations during the past year, and
its present condition, to which Mr. Slack had added a résumé of some
recent investigations with minute organisms. The Society was in-
debted to Dr. Millar for preparing an Obituary Notice of the late
President. As Dr. Millar had some further additions to make, this
and similar notices would be taken as read, and would appear in the
next number of the Journal.

At the conclusion of the Address, Mr. Glaisher then moved that a
special vote of thanks be given to Mr. Slack for the admirable Address
he had given, undertaken at very short notice in consequence of the
lamented event before referred to.

The motion was unanimously agreed to; and it was also resolved
that the Address be printed in the usual way.

The Chairman having announced that the Scrutineers had reported
that the officers, as proposed by the Council, had been unanimously
elected, the meeting was adjourned to the 1st March next, the alteration
in the day of meeting commencing from this time.

Donations to the Library and Cabinet, from January 11th to
February 8th, 1871 :—

From

Land and Water. ey cay ee See cil oss, LOSLOrs
Nature. Weekly Sd ea ese) vee CLOT
Society of Arts 7 ournal, Weekly, Vsti Say Se) 2. ) Societys
Atheneum. Weekly .. ie tin te
Journal of the London Institution, Nos. land2 .. Institution.
On a New Genus of Graptolites. By John Hopkin-

son, E:G.S. .. Author.
The Annual Report of ‘the Brighton ‘and Sussex Natural

History Society .. Society.
Notes of some of the Researches i in Anatomy, Botany, & &e.

By George Gulliver, F.R.S. Pes) Lee ee Author.
J. D. Miller's Diatomaceen- probe-pli atte .. .. .. .. The Rev. R. N. Browne.
Six Slides of Copper Ore, &e. .. en 3) \Lhe Reo RN. Brawnes
Two hundred and ten Slides of Marine Ales . meee) as, He TS Wistling, see

* The Editor is by no means responsible for this error.

142 PROCEEDINGS OF SOCIETIES.

The following were elected Fellows of the Society :—

William Alfred Bevington, Esq. |
William Ackland, Esq., L.S.A. }
Charles Mostyn, Esq,
H. R. Webb, Esq.
Watter W. Retves,
Assist.-Secretary.

RicHarp Mestayer, Treasurer, in Account witH THE Roya.
Microscopican Society.

1870. £. 8. d. || 1870. foes C.
Balance brought from last | Hardwicke for Journal .. 260 6 6
year . bah Msp lou One Insurance... ee) eC
Subscriptions for 1867 -- 1 1 0j| King’s College, rent, ke, ee)
+5 1868 5a) itehen fey p Ol #3 3 refreshments 2911 9
i. 1869 aoc On ~ soirée, 1870 18 19 6
55 1870 :. 833 18 0 || Instruments and repairs .. 5 3 0
- 1871 cus I OI TRO Cabinet-maker | su;-24)0-s mon) 6
Admission fees .. .. .. 31,10 O Books .. Sep ee
Compositions : .. 5614 0 || Stationery and printing oe gv’ 9
Dividends on 1059. 6s. 2d. Petty cash” == se eee LO
Consols .. 31 3 8 Assistant- Seeretary ce Ce BESIEO! 0
Transferred from the Charter Reporter ae ae Diaoe 0
nner abe aise OO, Ui OL Diagrams... Zoe 0
| Debt due from the late Col-
} lector... ier. 0
eo
| 527 6 4
|| Balance due from Treasurer,
| 31st Dec., 1870.. ; Bey
£561 8 11 £561 8/11 |

Examined and found correct,

W. T. SUFFOLK,

JAMES HILTON, \ eS

BrigHTON AND Sussex Narurat History Socrery.

November 24th.—Microscopical Meeting. Mr. Glaisyer, Vice-
President, in the chair.

Mr. R. Glaisyer reported the receipt for the Society’s cabinet from
Mr. Hennah of three slides of tooth sections, made by the late Mr. T. |
Eden, and of two slides from Mr. Wonfor. |

Mr. Dennant reported that for the grinding sections of teeth he |
had found Water-of-Ayr stone, used in the same way as pumice stone
with ground glass, gave better results than the pumice stone. He
considered the operation quicker, and that there were fewer scratches.
He should like to know the best means of staining teeth or bone.

Dr. Hallifax recommended carmine; but Mr. Hennah preferred
magenta, a drop or two in water was quite sufficient.

In answer to an inquiry from Mr. Peto as to the office of the
lacune and canaliculi in bone, and the supposed cause of the difference

i i

PROCEEDINGS OF SOCIETIES. 143

in their size, Dr. Hallifax described the vertebrate skeleton and its
structure, pointed out its power of repairing injury, its special purposes
of leverage, &c., and discussed the haversian system, the lacune and
canaliculi, all of which he considered subservient to the purposes of
nutrition, and mentioned that by the process known as decalcification
he had been able to make three sections with his cutting instrument,
in which the haversian system was well illustrated.

Mr. Hennah stated that in the opinion of some authorities the
lacune and canaliculi differed in size, according to the relative sizes
of the blood globules.

Mr. Wonfor thought this would hardly hold good in all cases, for
in some of the Reptilia, having large blood globules, the lacune and
canaliculi were small.

The meeting then became a conversazione for the exhibition of
specimens of “Bone and Ailied Structures.”

Mr. Hennah exhibited cartilage dry and in gelatine, and sections
of bone in balsam.

Mr. Dennant exhibited sections of teeth showing ramifications of
caries, and sections of bone.

Mr. Peto exhibited sections of bone, recent and fossil, and of teeth
mounted in balsam.

Mr. Sewell exhibited human fcetal and other bone sections.

Mr. Wonfor exhibited sections of bone, bony scales, ivory, teeth
and palate teeth, dry and in balsam,

It was determined that the Microscopical Meeting for Dec. 22nd
should be on “ Shell Structure.”

December 8th.—Ordinary Meeting. Mr. Sewell, Vice-President,
in the chair.

Mr. H. Pratt was elected an ordinary member.

Mr. Wonfor, Hon. Sec., announced the receipt (from the author)
of a copy of a paper read before the Eastbourne Natural History
Society, by Mr. F. C. 8. Roper, “On the Polyzoa found at East-
bourne.”

The Rev. J. C. Walker exhibited a curious flower, commonly
called “'The Rose of Jericho,” and which, when placed in water, un-
folded itself. 'This property is possessed by several plants, viz. the
true Rose of Jericho, which belongs to another family ; by one of the
Lycopodiums, sold under the name of the Resurrection Plant ; and by
some of the lichens, as well as by the spores and seed-vessels of some
plants, notably in the case of Erodiums, one of which has been used
as a hygroscope, owing to their being acted upon by changes of
moisture and dryness. An example of the Lycopods, L. lepidophyllum,
possessing this property, was shown by Mr. Wonfor. The difference
between this plant and the Roses of Jericho is, that, after being placed
in water for twenty-four hours, the plant may be potted, and will grow
like any other lycopod.

Mr. R. Glaisyer exhibited specimens of lias, from Dudley, con-
taining fossils, among which was a perfect trilobite.

Mr. Nash exhibited shale, from which the petroleum oil is ex-
tracted, and containing fossil fish, the bones of which were distinctly

144 PROCEEDINGS OF SOCIETIES.

seen; crude petroleum; petroleum scales, or the solid extract ; puri-
fied wax, and manufactured articles from the same, illustrating the
petroleum from its crude to its manufactured form.

Mr. Hennah exhibited some very beautiful specimens of arsenite
of copper, collected by his grandfather from Cornish mines.

Mr. Wonfor exhibited three birds, lent by Messrs. Pratt—the
Iceland gull, a very rare bird in Sussex, shot recently off Brighton
by Mr. Goldsmid ; the shore lark, an occasional visitor; and the grey
phalerope, which had been somewhat abundant in the south this year ;
also a specimen of the striped hawk moth, D. livornica, caught at
Brighton this year, and varieties of the poplar hawk moth, S. populi.

Mr. Sewell exhibited a bone, obtained at a depth of 14 feet in
Norfolk Square, which resembled a human tibia more than the bone of
any of the animals,—such as the horse, ox, elephant, or deer,—asso-
ciated with the Post-Pliocene.

Mr. C. Smith exhibited and presented for the Society’s Herbarium
two mosses, new to Britain, recently discovered by Mr. Mitten in
Sussex, viz. Pottia littoralis, found near Aldrington, and Pottia asperu-
losa, near Hastings. They had not yet been described, nor had they
been seen by the Botanical world at present. He had been fortunate
enough to find one of them since Mr. Mitten’s discovery.

December 22nd.—Microscopical Meeting. Mr. Glaisyer, Vice-
President, in the chair.

Mr. R. Glaisyer announced the receipt of twelve slides from Mr.
Gwatkin, three from Mr. Wonfor, and two slides of spicula of the new
sponge Pheronema Grayi, obtained in the “ Norna Expedition,” off the
coast of Spain, from Mr. Marshall Hall, the owner of the yacht; and
a reprint from the ‘Monthly Microscopical Journal’ of a paper on
the same sponge by Mr. W. 8. Kent. Votes of thanks were given to
these gentlemen.

Mr. Hennah called attention to a series of cheap lenses by Gundlach,
very kindly lent to him by Mr. T. Curties, of the establishment of
C. Baker, 244, High Holborn, the agent for England, for exhibition
before the Society. Since the last meeting he had had an opportunity
of carefully examining, through the courtesy of Mr. Curties, a series
of Gundlach’s lenses, ranging from a} toa 4th. Thetand 1th were
not good, the }rd was a perfect lens, the same might be said of the
ysth and th. The last, which was on the immersion principle, was
especially nsefall, as giving 600 diameters with a low eye-piece, and
working through thick glass. No recent additions to the microscope
have equalled these lenses as instruments of research in minute
natural history. The +;th, though very good, yet being a dry lens,
approached nearer than the ;',th, and was in power equivalent to a
Ross’s 1th; they also worked through thick glass, and were not inferior
to any lenses he had seen, though Ross’s }th was superior on P. angu-
latum. 'They would be very valuable to those who did not possess
English lenses of this power, especially as in the whole series the
price of the objectives was about one-third that of English ones. Find-
ing the first specimens so good, he had asked Mr. Curties to send
others, so that they might be able to judge if the supply would be

——.

PROCEEDINGS OF SOCIETIES. 145

equal to the specimens first sent. As far as he had been able to judge,
they were still of the first class. He felt personally indebted to Mr.
Curties for his kindness in allowing him time for a fair judgment,
and thought the members, as microscopists, were under an obligation
to him for the opportunity he had afforded them.

Mr. Sewell, who had a 4rd out of the first batch, was well satisfied
with its performance, and could not wish for a better lens.

Mr. Wonfor expressed himself as well pleased with what he had
already seen, and doubted not the members would be delighted with
these lenses, not only as regarded their performance, but also their
cheapness. He would suggest that the objects to be shown that even-
ing should be seen with Gundlach’s lenses, and a comparison be made
with other objectives by the members present. Upon all occasions
Mr. Curties had acted in a most courteous and kindly way to the
Society, and he should have great pleasure in proposing a cordial
vote of thanks to him for this and other acts of kindness.

Mr. Sewell seconded the resolution, which was carried unanimously.

Mr. Wonfor then introduced the subject for the evening, “Shell
Structure,” by describing the structure and component parts of the shells
among the Mollusca, at one time supposed to be mere inorganic exu-
dations, cemented together by animal glue. It was now known that
their shells were composed of animal and calcareous matter, the first
constituting a membranaceous basis, forming cells, with hexagonal
walls or laminz, more or less wrinkled; some shells were traversed
by tubes, others by canals, with trumpet-shaped orifices ; in each case
the calcareous matter giving solidity to the membranaceous tissue.
The internal layer, of a nacreous nature, was in many very beautiful.
Some of the porcellaneous shells were made up of three distinct layers
of a similar structure. In the Crustacea, especially the crab, four
layers could be distinctly made out, one of which strongly resembled
dentine, except that the tubuli did not branch, but remained of the
same size throughout. It was in the cellular layer where the pig-
mentary matter, which imparted the colour to the shell, was to be
found. The membranaceous matter could best be made out by decal-
cifying the shell and cutting thin sections.

The meeting then became a conversazione, when Mr. Hennah ex-
hibited, under Gundlach’s ;,th and ,!,th, sections of crab and cowrie-
shell, mounted with thick covers. The performance was perfect.
Afterwards, for lined objects, Pleurosigma angulatum and tasselled
scales of white butterfly were shown. The ,,th gave very good
results ; but the ;',th did not equal Beck’s popular 3th.

Mr. Sewell exhibited with a 1rd, sections of pearl and crab-shell.
This lens was pronounced very good.

Mr. Peto, under a } and a 1 inch, with convex front, exhibited
sections of pinna-shell. Both lenses were excellent.

Mr. Wonfor, under a couple of irds, exhibited egg-shell of garden
snail, sections of shell of terebratula, shells of prawn, shrimps, &e.
These lenses were very good, and when compared with Mr. Sewell’s
ird to test equality of performance, were so much alike that scarcely
a difference, if any, could be detected.

146 PROCEEDINGS OF SOCIETIES.

Mr. R. Glaisyer exhibited shells of nautilus, &c., cut through to
show their chambered character.

It was resolved that the subject for the January Microscopical
Meeting should be “'T'he Use of the Polariscope in the Determination
of Structure.”

January 12th, 1871. Ordinary Meeting. Mr. F. Merrifield, Presi-
dent, in the chair.—Captain Walker and Mr. W. Saunders were
elected ordinary members.

Mr. Wonfor, Hon. Sec., reported the receipt for the library of the |
‘Third Annual Report and Proceedings of the Eastbourne Natural
History Society’ from the Secretary, and a pamphlet, by Dr. Stevens,
‘On the Flint Implements found at St. Mary Bourne,’ from the
author. Votes of thanks were passed to the donors.

Mr. J. Howell read a paper “On the Brighton Cliff Formation ”
as revealed by the Main Drainage excavations.

Reapinc Microscopican Socrery.*

January 3rd, 1871.—Captain Lang presided, and Dr. Shettle re-
sumed the reading of his paper, “ On the Action of Electricity in the
Formation of Nerve Cells and Fibres;” more particularly referring
to Lockhart Clarke’s investigations as to the structure of the spinal
cord in the foetal sheep, and from them in connection with the laws of
electrical action, deducing conclusions as to the formation of nuclei ;
the aggregation of clusters of nuclei; the aggregation of nuclei and
formation of cell walls around them; their conversion into elongated
fibres, and the formation of cells of sigmoid shape.

Mr. J. C. Simpson read a paper “On the Electrolytical Coagula-
tion of Milk.” After a few words in justification of bringing forward
(what might be considered) a physical phenomenon in connection
with a professedly Microscopical Society, the writer stated how, upon
one occasion, when testing the action of a small voltaic battery and
finding its action too strong, he was led, by accident, and as a matter
of convenience, to interpose a little slightly-milky water in the circuit,
and soon noticed a sort of ring forming round the end of one of the
immersed wires.

Having then referred to the microscopic and chemical characters
of milk, and to its coagulation by acids, he described the appearances
presented by the passage of a current of electricity, as seen under the
microscope. A drop of a watery solution of milk was placed on a
slip of glass, and under the usual thin glass cover electricity being
transmitted, gases were given off abundantly at both poles. Around
the negative pole the milk globules were thinned out, and seemed to
repel each other, while round the positive pole they seemed to coalesce.
At the same time a sort of ring or wave spread out from the positive
pole. Then suddenly, and, rather nearer to the positive pole, a
brownish line or fold appeared ; the globules quickly flowed up to it
on both sides, and it gradually lengthened and widened, until it
formed an irregular curve round the positive pole. This flow of

* Report supplied by Mr. B, J. Austin.

PROCEEDINGS OF SOCIETIES. 147

globules soon ceased upon the positive side, but continued on the
negative side. The centre of this wall of milk globules became more
and more transparent, while the wall itself grew thicker. On re-
versing the current, the transparency at once disappeared, and a line
of globules started off from both sides into the liquid, but on again
transmitting the current as before they were again attracted. On
permanently changing the direction of the current this wall was en-
tirely dispersed and reformed near the opposite pole. The wall itself
was seen as a thin transparent gelatinous tissue rising from the surface
of the slide, and was considered to be a true coagulation.

A precisely similar experiment upon a drop of water containing a
few grains of fine flour, showed the formation of a similar wall; but
in this case the wall quickly resolved itself into a spiral-shaped cloud
of very fine particles, which spread out indefinitely towards the posi-
tive pole; and soon after vortices were seen in this mass of particles,
while within them plates and rings of the particles themselves were
seen revolving with different degrees of rapidity. The motion stopped
at every break of the current.

That the flow of milk globules was not due to the flow of gaseous
bubbles (evolved by the electrolysis) was proved by repeating the ex-
periments under conditions which allowed the gas to rise at once into
the air; and also under conditions whereby no gas was evolved, when
a similar flow of particles in the same direction uniformly occurred.

The writer’s explanation was that the phenomenon arises from the
electrolysis of the water in the milk, and that the coagulation takes
place in the casein, but he believes that the experiments of Jiirgensen
and of Quincke upon the mechanical transport of fine particles from
‘one pole to another, do not account for the somewhat similar motions
observed by him in the coagulation of casein and other albuminoids.

The same methods of investigation being applied to albumen were
found to lead to different results, according to the strength of the solu-
tion; undiluted egg-albumen at once yielding a thick wall round the
positive pole. From a thinner solution the wall is strangely broken
and renewed, while from one thinner still the coagulum forms between
the two poles, but is soon broken up into dust-like particles.

The fact that albumen coagulates at the positive pole is well
known, having been observed by M. Lasaigne; and the conversion of
albumen into fibrin has been described by Mr. A. H. Smee, in a paper
published in the ‘ Proceedings of the Royal Society’ for 1863.

A watery solution of blood serum yielded a coagulum at the june-
tion of the waves from the poles, the side towards the negative pole
being of a bright scarlet colour, while that towards the positive pole
appeared green. In the case of undiluted fresh blood, coagulation
began near the positive pole, but there was no attraction of disks.

A solution of legumin from bitter almonds presented similar ap-
pearances to milk, except that the coagulum was darker and more
tenacious, but the bright median portion was wanting.

February 7th, 1871.—Dr. Shettle concluded the reading of his

paper “ On the Evidence to be obtained as to the Nature of the Vital
Force, from a minute study of Anatomy, and of the Laws which

148 BIBLIOGRAPHY.

regulate the Electro-Magnetic Force.” This last portion of the
paper more particularly referred to the action of electric currents in
the production of cell-walls and cells which, becoming polarized,
would elongate or become crescentic, and by an extension of their
lines of force would even form tubes, as in nerve-tissue. The rotation
of the frog-embryo within the egg was considered due to dextrorsal
currents. The source of this electricity was referred to a magnetic
condition of the arterial blood from its absorption of oxygen; and ex-
periments as to the magnetism of arterial and venous bloods were
cited in support of this idea. The bi-concave form of the blood
corpuscles, their adherence by their flattened surfaces, the connection
of osmosis with electricity, and finally Dr. W. B. Richardson’s experi-
ments as to the conducting power of blood, were held to establish the
theory.

Captain Lang exhibited the eggs of a parasite (order Anopleura,
genus Docophorus) found in vast numbers on the down of a kestrel
hawk lately dead. Examination after death showed that almost all
the down feathers had been eaten away, whilst on the few remaining
feathers these eggs were most abundant. They were mere empty
shells, yet but one dead parasite and no living ones could be seen. It
was presumed that the death of the bird (otherwise apparently
healthy) resulted from exposure to cold in consequence of the loss of
its downy covering.

BIBLIOGRAPHY.

Botanische Abhandlungen aus dem Gebiet der Morphologie und
Physiologie. Herausgegeben von J. Hanstein. Ist Heft. Bonn.
Marcus.

Untersuchungen iiber Bau und Entwickelung der Arthropoden.
Von Ant. Dohrn. 2nd Heft mit 8 taf. Leipzig. Engelmann.

Biologische Studien. Studien iiber Moneren und andere Protisten
nebst einer Rede iiber Entwickelungsgang und Aufgabe der Zoologie.
Von E. Haeckel. Leipzig. Engelmann.

Beitrige zur vergleichenden Neurologie der Wirbelthiere. Von
N. Miklucho-Maclay. I. Das Gehirn der Selachier. II. Das Mittel-
hern der Ganoiden und Teleostier. Leipzig. Engelmann.

Grundziige einer Spongien-F'auna des Atlantischen Gebietes. Oscar
Schmidt. Leipzig. Engelmann.

Beitrige zur Anatomie und Physiologie. V. Band. 2nd Heft.
C. Eckhard. Giessen. Roth.

Physiologisch-anatomische Untersuchungen, iiber den Uterus.
C. Friedlinder. Leipzig. Simmel & Co.

Histologie générale. Etude critique sur Virchow et la Pathologie
cellulaire. Par P. Jousset. Paris.

Beitraige zur Histologie des Gehérorganes. C. Rudinger. Munchen.

Immersion Lenses and New Refractometers. 65

V.—On the History, Refractions, Definition, and Powers of
Immersion Lenses and New Refractometers. By Roysron-
Picorr, M.A., M.D. Cantab., M.R.C.P., Fellow of the Cam-
bridge Philosophical and the Royal Astronomical and Micro-
scopical Societies of London, formerly Fellow of St. Peter’s
College, Cambridge.

(Part I.)

I.—Hisrory has handed down to us the labours of CLAUDIUS
Proremy, the Father of Optics. His celebrated experiment of ren-
dering a coin visible placed in an empty vessel by filling it with

NOTICE TO BINDER.

In consequence of an error in page 66
’

Number XXVI., a corrected leaf is now
sent for insertion.

Bent Oar in Water. Refraction from Air into Water.

His very ingenious mode of settling these points, as it really
involves the important principle of the MODERN IMMERSION LENS,
may not be uninteresting to those unacquainted with the experi-
ments. Observing the crooked image of an oar in water, and the
curious apparent rising of the money as the water is poured into the
vessel, he had a semi-cylinder of “pure glass” constructed, to which
he adjusted a graduated circle, so that the diameter of the cylinder
coincided precisely with the diameter of the graduated circle above
mentioned, and also with the surface of the water. A small
coloured body was placed at the centre of the circle; a second
' similarly fitted to one of the quadrants out of the water; a third.
slided on the lower part of the graduated circle immersed in the
water. Observations were then made upon the angles of incidence
and refraction of such a degree of accuracy as to excite our admira-
tion after a lapse of nearly two thousand years. The determination
of the conditions of refraction through A WATER LENS Was thus
anciently effected sufficiently exact for all the practical purposes of
modern theory.

,
*

148 BIBLIOGRAPHY.

regulate the Electro-Magnetic Force.” This last portion of the
paper more particularly referred to the action of electric currents in
the production of cell-walls and cells which, becoming polarized,
would elongate or become crescentic, and by an extension of their
lines of force would even form tubes, as in nerve-tissue. The rotation
of the frog-embryo within the egg was considered due to dextrorsal
currents. The source of this electricity was referred to a magnetic
condition of the arterial blood from its absorption of oxygen; and ex-
periments as to the magnetism of arterial and venous bloods were
cited in support of this idea. The bi-concave form of the blood
corpuscles, their adherence by their flattened surfaces, the connection
of osmosis with electricity, and finally Dr. W. B. Richardson’s experi-
ments as to the conducting power of blood, were held to establish the

avwiusvus muuandaungen aus dem Gebiet der Morphologie und
Physiologie. Herausgegeben von J. Hanstein. Ist Heft. Bonn.
Marcus.

Untersuchungen iiber Bau und Entwickelung der Arthropoden.
Von Ant. Dohrn. 2nd Heft mit 8 taf. Leipzig. Engelmann.

Biologische Studien. Studien iiber Moneren und andere Protisten
nebst einer Rede iiber Entwickelungsgang und Aufgabe der Zoologie.
Von E. Haeckel. Leipzig. Engelmann.

Beitrage zur vergleichenden Neurologie der Wirbelthiere. Von
N. Miklucho-Maclay. I. Das Gehirn der Selachier. II. Das Mittel-
hern der Ganoiden und Teleostier. Leipzig. Engelmann.

Grundziige einer Spongien-Fauna des Atlantischen Gebietes. Oscar
Schmidt. Leipzig. Engelmann.

Beitrige zur Anatomie und Physiologie. V. Band. 2nd Heft.
C. Eckhard. Giessen. Roth.

Physiologisch-anatomische Untersuchungen, tiber den Uterus.
C. Friedlinder. Leipzig. Simmel & Co.

Histologie générale. Etude critique sur Virchow et la Pathologie
cellulaire. Par P. Jousset. Paris.

Beitrage zur Histologie des Gehérorganes. C. Rudinger. Munchen.

Immersion Lenses and New Refractometers. 65

V.—On the History, Refractions, Definition, and Powers of
Immersion Lenses and New Refractomeers. By Roystoy-
Pigott, M.A., M.D. Cantab., M.R.C.P., Fellow of the Cam-
bridge Philosophical and the Royal Astronomical and Micro-
scopical Societies of London, formerly Fellow of St. Peter’s
College, Cambridge.

(Part I.)

I.—History has handed down to us the labours of Cuaupius
Protemy, the Father of Optics. His celebrated experiment of ren-
dering a coin visible placed in an empty vessel by filling it with
water, was perhaps the first scientific attempt at experimental
refraction : thence he proceeded to measure the refraction of light
passing from water into air, from air into glass, and lastly from
water into glass. He sagaciously avoided the deviation from glass
into air by taking care the rays should emerge perpendicularly to
the surface of the glass.

Bent Oar in Water. Refraction from Air into Water.

His very ingenious mode of settling these points, as it really
involves the important principle of the MODERN DDOWERSION LENS,
may not be uninteresting to those unacquainted with the experi-
ments. Observing the crooked image of an oar in water, and the
curious apparent rising of the money as the water is poured into the
vessel, he had a semi-cylinder of “pure glass” constructed, to which
he adjusted a graduated circle, so that the diameter of the cylinder
coincided precisely with the diameter of the graduated circle above
mentioned, and also with the surface of the water. A small
coloured body was placed at the centre of the circle; a second
_ sumilarly fitted to one of the quadrants out of the water; a third
slided on the lower part of the graduated circle immersed in the
water. Observations were then made upon the angles of incidence
and refraction of such a degree of accuracy as to excite our admira-
tion after a lapse of nearly two thousand years. The determination
of the conditions of refraction through 4 WATER LENS was thus
anciently effected sufficiently exact for all the practical purposes of
modern theory.

*

66 Immersion Lenses and New Refractometers.

Ptolemy observed that the refractions from water into glass
were less than any he had previously observed. The following were
some of the results he obtained :—

Ciavpius Protemy’s TABLES.

REFRACTIONS FROM GLASS INTO Arn. || REFRACTIONS FROM WATER INTO Heche

Angle of Incidence. | Angles of Refraction. || Angle of Incidence. |Angles of Refraction.

0 0) 0 v1) 0 8
20 13 30 20 18 30
60 34 30 60 49 30
80 42 0 80 62 0

The first Table on the left, for the 4 angles, gives the value of
the refractive index for Ptolemy’s “ pure glass” at 1°48, 1°53,
1°47; the mean of which is 1°49, or nearly the refractive index
for our common glass, and evidences the singular care Ptolemy must
have taken in his experiments.

For the water refractions the values of the index of refraction
between glass and water are (by the refractometer, to save the cal-
culation by logarithms), for 60° and 80° in the Table, nearly 1-500
and 1°336, a surprising approximation to the true values by this
primitive method.

Protemy’s Immersion LENS.

SEMICYLINDER

Refraction from Water into Glass.

If the glass cylinder be removed, then the ray would be turned
back by the surface of the water, and internally reflected, instead
of being refracted.

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THE

MONTHLY MICROSCOPICAL JOURNAL.

APRIL 1, 1871.

I.—On the Structure of the Podura Scale and certain other Test-
objects, and of their Representation by Photo-micrography.
By Lieut.-Col. Dr. J. J. Woopwarp, U.S. Army.
(Read before the Royau Microscorican Society, March 1, 1871.)
Puates LXXIX. anp LXXX.

Tue ‘ Monthly Microscopical Journal’ for December, 1869, contains
a paper “On High-power Definition,” by Dr. G. W. Royston-
Pigott. This essay was rapidly followed by others on allied sub-
jects, the whole constituting a remarkable series. They contain
mathematical discussions of many points connected with the optical
questions involved in the use of objectives, and especially of immer-
sion objectives ; assert the existence of “a certain residuary aberra-
tion, chiefly spherical,” in the best modern objectives ;* claim the
correction of this aberration, partly by special modes of illumina-
tion, but chiefly by means of a vaguely-described optical combina-
tion, “ the Aplanatic Searcher ;”t and finally, contain many interest-
ing and some novel statements with regard to the structure of
several test-objects, and especially the Podura scale.

These papers have provoked considerable discussion: in England,
and perhaps a few temperate remarks on the subject by a Trans-
atlantic observer will not be without interest.

My observations will relate chiefly to the structure of the
Podura scale and a few other test-objects, and to the possibility of
representing these objects photographically.

The mathematical portions of Dr. Pigott’s papers must be left
to such appreciation as the mathematicians may award; but his
general assertion that our finest objectives are not perfectly cor-
rected, is doubtless substantially true. It is well known that the
lenses sent out by the best makers continue annually to improve;
and I, for one, should be sorry to believe that we have yet reached
the limit of perfectibility. How far the “ Aplanatic Searcher” can
be regarded as a valuable addition to the optical appliances at the
disposal of the microscopist, is a question on which, perhaps, any

* «Monthly Microscopical Journal,’ vol. ii., p. 296. + Ib., vol. iv., p. 42.
VOL. V. M

150 Transactions of the

judgment of mine would be premature. Last July I wrote to
Messrs. Powell and Lealand, requesting them to make one for the
Army Medical Museum, intending to try it in connection with the
immersion ygth of these makers. They were at the time, as I
understood, constructing one for Dr. Maddox, and I asked them, so
soon as that was finished to the satisfaction of Dr. Pigott, to make
the one for the Museum. This instrument has not yet reached me,
and from the information afforded by my London correspondent, I
fear I shall not receive it at any very early day. I am, however,
not unwilling to admit that demonstration alone could lead me to
believe that any optical combination introduced into the body of
the microscope, between the eye-piece and the objective, would
result otherwise than in loss of light and impaired definition. Espe-
cially should I anticipate this result, if the optical combination was
such as to increase the magnifying power. ‘This is the result with
all the various achromatic amplifiers I have experimented with, and
I have learned nothing as yet of the “ Aplanatic Searcher ” which
would lead me to suppose it escapes from the same defects. I
would suggest to Dr. Pigott a simple practical test that would go
far towards dispelling the doubts on this subject, which, so far as I
have been able to learn, are very generally entertained. ‘This test
is afforded by an examination of Nobert’s plate with and without
the Searcher. Can an objective which with eye-pieces alone just
resolves any given band on the test-plate be made to resolve the
next higher band by the Searcher? Will not its performance
rather fall to the next band below, or even farther ? It would also
be interesting to know whether the nineteenth band of Nobert’s
plate can be resolved by any objective used with the “ Aplanatic
Searcher.”

With regard to the Podura scale, it gives me great pleasure to
express the opinion that Dr. Pigott’s observations constitute a
valuable addition to our knowledge of this test. On the coarser
Degeeria scale I have had no difficulty in making out appearances
which, so far as I can gather from Dr. Pigott’s own descriptions and
the published discussions with regard to his views, are substantially
the same as seen and shown by him. And even on the more minutely
marked and difficult Lepidocyrtus scale I have been able to develop
images which seem to be substantially similar. In arriving at these
results I have used chiefly the immersion th and ygth of Powell
and Lealand, with the ordinary eye-pieces.

When Dr. Pigott’s paper in the ‘ Monthly Microscopical Journal ’
of December, 1869, first reached me, my attention was especially
drawn to his novel views with regard to the Podura scale by the
personal allusion to myself on page 299. The paragraph is rather
indefinite, apparently owing to a misprint; but I understand the
language used as intimating that it was chiefly the examination of

Royal Microscopical Society. Ld5k

certain photographs of the Podura scale, made at the Army Medical
Museum, which induced him to publish at that time the results of
his previous, but still incomplete, studies. As these photographs
were all made with dry lenses, I took an early opportunity to re-
examine the scale with the immersion 7th of Powell and Lealand.
But although direct sunlight reflected from a plain mirror gave
glimpses of a structure distantly resembling the new descriptions,
the resolution was so unsatisfactory that I was inclined to regard
the appearances as spurious, and more convinced than ever that the
scale was properly resolved when the exclamation marks were
shown. I made the two photographs sent with my note of
April 23, 1870, to Mr. Hogg.* Copies of these photographs accom-
pany the present paper. No. I. shows the notes of exclamation as
figured by Mr. Richard Beck, in his work on the Microscope. In
No. II. there is a pretty distinct knob at the head of each note of
exclamation. Both photographs are magnified 3000 diameters by
Powell and Lealand’s immersion ,},th.

In my note to Mr. Hogg I expressed two wishes, both of which,
I am happy to state, have been gratified. The first was, that he
would obtain for me, from Dr. Pigott, one or two of the slides used
for his observations ; the second, that my friend Dr. Maddox might
be induced to photograph the Podura scale as seen by Dr. Pigott.

In response to the first of these wishes, I received from Mr.
Hogg two slides; one of the test Podura, the other labelled De-
geeria Nigro-maculata;{ the first from Dr. Pigott, the second from
Mr. 8. J. McIntire. To these gentlemen I desire to express my
sincere thanks.

The response to my second wish was not less satisfactory. Dr.
Maddox undertook the photographic representation of both Degeeria
and test Podura, and has kindly sent me copies of the interesting
series of pictures exhibited by him to the Society last June.t

Under these circumstances I renewed my observations, with the
intention of making a series of photo-micrographs representing such
appearances as I should be able to find.

And here I desire to offer a few remarks with regard to the real
significance of photo-micrography, as a means of recording honestly,
and without modifications of subjective origin, the appearances
actually seen in the case of difficult test-objects.

In his paper “On the Diatom Prism” § the late lamented Presi-
dent of the Royal Microscopical Society, the Rev. J. B. Reade,

* ‘Monthly Microscopical Journal,’ vol. iii., p. 324.

+ Sir John Lubbock, in his “ Notes on the Thysanura,” ‘ Lin. Soc. Trans.,’
vol. xxvii., p. 277, names this scaled species of Degeeria, Seira domestica (seira, a
chain), from the circumstances that it “forms a very interesting link (or chain)
between several genera, some of which approach very closely to Lepidocyrtus,”

&e.
{ ‘Monthly Microscopical Journal,’ vol. iv., pp. 51, 67. § Ib., vol. ii., p. 5.
M 2

152 Transactions of the

makes a remark which Dr. Pigott interprets as underrating this
mode of representation. After describing the arrangement of the
hemispherical elevation on Plewrosigma quadratum and P. angu-
latum, he says— Hence, under the illusion of the common methods
of illumination, which deal with shadows only, and under deep
powers, the markings of those diatoms are described and figured as
hexagons, with the sides and centres light and dark, or vice versa,
and PHOTOGRAPHY stands by as an attesting witness.”

Dr. Pigott, in his paper published last November,* quotes this
sentence and expresses himself still more strongly. Speaking of
the beading he describes on the Podura scale, he says :—“ It would
seem the actinic glasses fail at present to perfect these views.
Illumination is a vexed question for the photographer, who has
never yet succeeded in displaying the spherules of the Amphipleura
pellucida, which so many English observers have seen microscopi-
cally. Unless, therefore, the defining power of photography at least
equals the human eye armed with the microscope, no reliable argu-
ment can be drawn from its failure or approximate revelations.
Indeed, the President notices that photography indicated hexagon
forms as the correct appearance for the diatom beadings, which we
now know is false.”

I do not think the President’s remarks were intended to express
the notion they are here quoted to support, and I believe I shall be
able to show that the paragraph from Dr. Pigott’s paper is inaccurate
in every particular. Indeed I am at a loss to understand how some
of the misconceptions it contains could have arisen at this late day.

In my first essay on photo-micrography, published in the
‘American Journal of Science and Arts,’ vol. xli., September,
1866, I expressed the opinion that photography was “adequate to
the satisfactory representation of all microscopical objects that do
not depend for their value on colours.” Subsequent experience has
satisfied me of the substantial justice of this opinion.

In examining objects with the microscope with white light,
both colour and form produce impressions upon the eye, and of
course it must be freely granted that photography cannot be counted
upon as a means of representing the colour phenomena. If, how-
ever, the microscope be illuminated by monochromatic light the
colour disappears and form alone is perceived, the object appearing
black or shaded on a ground of the colour employed. A trial will
convince anyone that so far from impairing definition, this method
considerably improves it, and for mere purposes of observation it
matters little what kind of monochromatic light is employed. I find
blue or violet light most agreeable to the eye, and these are also
the colours suitable for photography ; but for mere observation any
other colour will answer. Such light may be obtained from the

* ‘Monthly Microscopical Journal,’ vol. iv., p. 254.

Royal Microseopical Society. 153

solar rays or from the electric lamp, either by means of a prism as
recommended by Count Castracane, or still more conveniently by
passing the rays through a coloured solution. I use, ordinarily, a
solution of the ammonio-sulphate of copper, which gives a bluish-
violet light approximating monochromatism sufficiently for all prac-
tical demands, whether of observation or photographic representa-
tion. When I compare the images of a difficult test as seen with
any objective by such monochromatic light, with the best attainable
with the lamp-lght illumination ordinarily employed, I must confess
to a feeling of astonishment that this simple and potent optical re-
source is not more generally employed by microscopists, aside from
all questions of photography. Not the least of its advantages is the
fact that in the case of those objects which decompose light readily,
the optical effects produced by this circumstance are at once elimi-
nated, and the observer is consequently better able to judge reasonably
with regard to the actual form.

Now, in the case of transparent objects, I do not hesitate to
assert that whatever can be discerned by “the human eye armed
with the microscope ” if monochromatic illumination is employed, can
be copied photographically in a manner that faithfully represents
every detail seen. And such representations have this superiority over
mere drawings or descriptions, that they are purely objective, and the
imagination or enthusiasm of the observer, which plays so consider-
able a ré/e in most drawings and descriptions, is wholly excluded.

I cannot, therefore, admit Dr. Pigott’s statement that ilumina-
tion is a “ vexed question for the photographer,” and his allusion to
the failures of “ the actinic glasses ” is apparently penned without a
consideration of the fact, that the immersion objectives of high
powers, which he so justly praises, require no special corrections
to fit them for photographic use, and are the very ones actually
employed. As for the Amphiplewra pellucida, there is nothing to
prevent anyone from photographing it quite as well as he may be
able to see it; to this, however, I shall recur again.

I sincerely believe that if microscopists generally would take the
trouble to master the simple steps necessary to enable them to record
their actual observations by photography, many bitter and unneces-
sary disputes would be avoided, and the solid progress of inquiry
into minute structure would be materially advanced. I am not,
however, disposed to exaggerate the just importance to be attached
to photographic representations, and must therefore add a few words
with regard to the real limitations of their usefulness.

All that can properly be claimed for photo-micrographs is, that
if the chemical work is well done, the picture will be a faithful
representation of whatever the observer is able to discern with
monochromatic light. Success in the chemical process is best and
most economically secured by employing a professional dark-room

154 Transactions of the

man, and any competent observer can judge of the quality of this
portion of the work, by examining the pictures themselves. The
microscopist who directs the work is best employed in seeing the
object, which, if he follows the simple methods I have described in
previous papers, will secure an image, of all he sees, on the sensitive
plate; but nothing more. There is no charm in photography which
can make it a touchstone of truth. If the objectives are imperfect ;
if the illumination is faulty; if the object is dirty or improperly
prepared, the photograph will tell the whole story as no drawing
or description would do. Others will be in a position to judge the
faults of the microscopist’s work, and this by the way is no doubt
one reason why so many observers shrink from the cruel sincerity
of this method of representation. When our improved objectives
first showed the markings on the Angulatum as hexagons, photo-
graphy faithfully reproduced them. When higher powers of better
definition showed the hexagons to be imperfectly seen circles,
photography had no difficulty in representing these. The hemi-
spheres rendered visible by a still further advance are shown in the
photographs which accompany this paper, and any future progress
resulting from better optical appliances will be chronicled in the
same manner. |

It is sometimes thoughtlessly objected that photo-micrography
reproduces the phenomena of interference or diffraction, as well as
the real structure. This I readily admit, and claim as an advantage,
for these phenomena are actually seen by the observer. If he merely
describes or draws, he omits all that he supposes belongs to this
category, and by so doing omits sometimes the essential; the photo-
graph omits nothing, and anyone who examines it is placed more
nearly on the plane of the original observer than he could be by any
other means, unless indeed he could sit by the observer's side and
look over his shoulder. This first limitation of the interpretation
of micro-photographs, therefore, is in fact only a guarantee of their
optical honesty.

There are other and different limitations, however, which require
mention. Thus our efforts to represent opaque objects, particularly
as seen with medium and high powers, have not as yet been crowned
with any great success. How far this results from the small amount
of labour hitherto expended in this direction, is not to the purpose ;
the success is not yet attained. So also there are certain yellow
objects, such as parts of imsects, for example, which transmit so little
violet light that as they are ordinarily prepared, photography fails
to exhibit all the details discernible by the eye. This difficulty,
however, is readily escaped by resorting to suitable bleaching pro-
cesses in the preparation of the objects, and these very processes
greatly improve the character of the objects for observation by
the eye.

Royal Microscopical Society. 155

Let me now return to the question of the structure of the
Podura scale. I began my investigation on the slide of Degeeria
Nigro-maculata sent by Mr. McIntire. The markings on these
scales were very bold, and the object was in every way a beautiful
one. As I first arranged the illumination the markings resembled
the notes of exclamation as seen on the ordinary test Podura, less
rounded at the heads, however, less pointed at the opposite extremity
of each marking, and the whole marked obliquely across by a delicate
series of transverse lines which were observed most distinctly
between the notes of exclamation, but which could readily be made
to appear to cover these also, when the fine adjustment was toyed
with. I soon found, however, that by proper management of the
illumination it was easy to make an appearance “ start into view”
which recalled at once the descriptions of Dr. Pigott, and Fig. 7 of
Plate XX XIII. accompanying his paper of December, 1869. In
that paper, it will be remembered, he asserted that the notes of
exclamation are mere optical effects produced by two sets of
beads arranged in “rouleaus” which cross each other at a small
angle.

tis says, of the beads on the surface of the scale nearest the
observer :—“ But with 2300 diameters they appear to lie on the
same plane and terminate abruptly on the basic membrane: upon
focussing for the strings of beads attached to the lower side, the
beading appears in the intercostal spaces. The upper beads are best
seen either green upon a pink ground or pink upon a greenish
ground.” And farther on :—“ By estimation, comparing these beads
with those of the P. Formosum of 35455th inch in diameter, the
observed Podura beads may be reckoned at spdoath to yspoooth of
an inch in diameter. The spines usually drawn really embrace in
general three or four beads.”

I understood, at the time, the foregoing description to be intended
for the scales of Lepidocyrtus curvicollis, and this opinion is con-
firmed by the remarks of Dr. Pigott in a subsequent paper ;* but
from the statement of Mr. McIntire that the Podura scale exhibited
by Dr. Pigott to the Microscopical Society was really a scale of
Macrotoma,t I presume that the coarser scales aided him in
arriving at his interpretation of the structure of Lepidocyrtus. In
any event, in his paper published in January, 1870, the same
structure is predicated of Macrotoma and Degeeria domestica, the
scales of which are said to “render that easy which is exceedingly
difficult in the regular test scale.” We are further told, in the same
paper, of the Degeeria,—* A lady who is now viewing the scale says,
‘the beads look just like rows of peas in a pod.’ ” t

The description given by Dr. Pigott in his first paper, as quoted

* «Monthly Microscopical Journal,’ vol. iv., p. 305. + Ib., vol. v., p. 12.
{ Ib., vol. iii., p. 13.

156 Transactions of the

above, may be taken as an approximate account of what I saw on
the Degeeria Nigro-maculata of McIntire.

The so-called beading was readily brought out with any power
above the half-inch. Immersion lenses gave more satisfactory views ;
and the very best effects being obtained by the immersion y'gth of
Powell and Lealand, I selected this lens for preparing the photo-
graphs. The appearance sought was readily obtained by oblique
light thrown lengthwise upon the scale from the concave mirror,
whether the illumination was afforded by a coal-oil lamp or by the
sun; but the best results were secured by using the achromatic con-
denser of Powell and Lealand, diaphragmed down so as to transmit
a pencil of small aperture, and obtaining obliquity by decentering
the condenser somewhat by means of the screw movements of the
secondary stage. Many other tricks of illumination were tried, but
the above gave, on the whole, results most nearly comparable with
Dr. Pigott’s description. I found the so-called beading was best
shown when the cover correction was so arranged as to show the
exclamation marks most distinctly. If, then, the illumination was
managed for the best display of the upper beading, I found on many
of the scales that a slight depression of the objective, by means of
the fine adjustment, brought the lower beading into view, and with
a still further slight depression the notes of exclamation were seen.
By slowly raising the objective in the same manner, the pheno-
mena were reproduced in reverse order. On some of the scales,
however, which I suppose to be those which le with their under-
surface towards the observer, as the objective was lowered the
exclamation points were first seen, then the two sets of beading,
one after the other. The colours of the beading appeared to me to
be alternately greenish and reddish (I should hardly choose the
word pink), according to the position of the fine adjustment. When
the upper rows of beading appeared reddish, the lower rows were
greenish, and vice versd. ‘The beading, however, at its very best,
always resembled the “rows of peas 2m a pod.” I praise the eyes
of the lady. They ran into each other; they appeared, rather, as
irregular ribbings, with alternate varicose swellings and constric-
tions, than as rows of such isolated spherules as are seen on so
many diatoms. In size they varied somewhat, but rows of five or
six seldom measured less than yo} oth, and often as much as goooth,
of an inch long. The colours were most brilliant and the approxi-
mation to the spherical form closest when the sunlight was used.
The handsomest results were obtained when the direct rays of the
sun were allowed to fall upon the mirror at such an angle that just
so much light should pass the condenser as the eye could bear with-
out being dazzled. On interpolating in the solar pencil a cell con-
taining a solution of the ammonio-sulphate of copper, the definition
was materially improved, but the varicose ribs looked now even less

Royal Microscopical Society. 157

like rows of isolated beads than before. The photographs show the
appearances attained in this manner.

Turning now to the Lepidocyrtus scale, I first examined the
one kindly sent me by Dr. Pigott. The slide was labelled as pre-
pared by Topping, and marked “ 1850, slide twenty years old.” An
accompanying note from Dr. Pigott to Mr. Hogg says :—“ The only
good scale is at the edge. The finest old-fashioned scales have
become exceedingly scarce.” Marks on the slide enabled me with-
out difficulty to identify this scale, which was of great size, being
nearly the ygoth of an inch in length. It was, however, disfigured
by two much smaller scales lying transversely beneath it, and
by granular débris which obscured a portion. Still, enough of
the scale was visible to serve for examination, and on this I had no
difficulty in observing a train of phenomena very similar to what I
saw on the Degeeria Nigro-maculata. ‘The beading, however, was
considerably smaller, though the scale was larger than any of the
Degeeria scales I selected for study. Encouraged by this result, I
worked over all the specimens. of Lepidocyrtus curvicollis in my
possession, including some slides recently received from Mr. E.
Wheeler. I was able to develop somewhat similar appearances
even in the smallest and most difficult scales. Of course, the smaller
the scale the less satisfactory the resemblance to rows of beads; but
varicose rubbing, more or less closely approximating that seen on
the Degeeria, could always be coaxed out, and the effects produced
im the Degeeria scales by raising and lowering the objective could
always be more or less distinctly obtained.

It must also be remarked that alike in the coarsest Degeeria
and the finest Lepidocyrtus scale, the beaded or varicose ribbing
appeared always to my eye less sharply defined than the exclama-
tion markings. And the photographs likewise possess this quality.
The same quality will be observed im Dr. Maddox’s photographs,
already alluded to. I am not disposed, however, to regard this cir-
cumstance as an expression of anything more than the fact, easily
recognized by the eye when monochromatic light is employed, that
the exclamation marks exhibit blacker shadows, and hence afford
images (whether to the eye or sensitive plate) possessed of greater
contrast than I have been able to give to the beaded ribbing by any
management I have yet tried. I must also freely admit that in the
smaller Lepidocyrtus scales the beaded character of the ribbing
becomes more and more indistinct to the eye, until perhaps its
existence is assumed rather on the basis of the similarity of the
appearances to those presented by the coarser scales, when these are
impertectly seen, than as an actual objective fact. I presume Dr.
Pigott also has experienced the same trouble, or he would not
lament the difficulty of finding the “ finest old-fashioned scales.”

As to the size of the beading in Lepidocyrtus I must regard

158 Transactions of the

Dr. Pigott’s estimate z5$5oth to rsc'sooth of an inch as inaccurate.
I suppose spdaath to sstooth of an inch will come much nearer the
actual truth. I have carefully measured small portions of the ribbing
and counted the number of bead-like swellings between the limits.
As the beads, if they may so be called, are in actual contact, in fact,
are continuous with each other, no allowance can be made for
imaginary interspaces. Dr. Pigott himself gives the elements for
correcting his estimate where he says, ‘“‘ The spines usually drawn ”
(z.e. the exclamation marks) “really embrace in general three or four
beads.” Now, bearing in mind that these beads are in contact, it is
only necessary to measure the length of the exclamation marks on
the finest Lepidocyrtus scale and divide the measure by four, to see
that such a figure as the yso'spoth of an inch is altogether out of
the question.

What then is the true structure of the Podura scale? Iam not
disposed to enter into any elaborate discussion: on this vexed point.
Whatever the ultimate decision shall be, we are all under many
obligations to Dr. Pigott for teaching us that with the improved
immersion objective a new series of phenomena can be observed which
had hitherto escaped attention. The true interpretation of these
phenomena lies perhaps still in the future, and probably reasonable

‘results are most likely to be attained by such investigations as have
been set on foot by Messrs. McIntire and Maddox.*

My object at the present time is simply to record in a tangible
form by photography, the actual phenomena as I am able to observe
them, in the hope that if improved objectives or other modifications
in the mode of observation should enable others to obtain more
satisfactory views, mine will at least answer the purpose of en-
couraging these more fortunate microscopists to record their results
in the same manner, and thus to expose them fairly for the instruc-
tion and honest criticism of their fellow-labourers.

Nevertheless, I do not hesitate to say that so far as I have been
able to arrive at any judgment I am disposed provisionally to agree
in the main with one of the possibilities advanced by Dr. Maddox.
I suppose the scale to be composed of two corrugated membranes,
each thrown into wavy longitudinal corrugations or ribs, and these
again crossed by transverse markings, which make the longitudinal
ribs appear varicose (or beaded), I suppose the varicose ribs of the
two opposite membranes which compose the scale to cross each other
at a small angle. In the proper position of the objective, the upper
series of varicose ribs comes into focus, while the lower ones are
imperfectly seen out of focus. By depressing the objective slightly
the lower ones come into focus, while the upper ones appear out of
focus. By depressing it still further the true ribbings are lost sight
of, and the exclamation marks, which I am disposed to think with

* ‘Monthly Microscopical Journal,’ vol. y., p. 31. ° ¢ Ib., vol. iv., p. 53, Fig. 3.

Royal Microscopical Society. 159

Dr. Pigott are a spurious appearance, come into view. That this
‘train of phenomena is reversed in certain scales would appear to
show a difference between the upper and the lower series of ribs.

I send the following photographs in illustration of the above
remarks :—

No. II. Photograph of Degeerta Nigro-maculata; 3100
diameters.—The scale was *0035 inch long and -0018 broad.

No. IV. Photograph of the same scale ; 2500 diameters.

No. V. Photograph of another scale of Degeeria Nigro-
maculata ; 2700 diameters.—The scale was ‘0034 inch long and
0013 broad.

No. VI. Photograph of the same; 2300 diameters.

No. VII. Photograph of the same; 960 diameters.

No. VIII. Photograph of the same scale, with several others
in view; 960 diameters.

No. IX. Photograph of part of the large scale of Lepidocyrtus
curvicollis on the slide sent by Dr. Pigott; 960 diameters.

No. X. Photograph of Lepidocyrtus scale s}sth of an inch long.

To the foregomg photographs of Degeeria and Lepidocyrtus I
add a few of certain diatoms. Long since Mr. Wenham arrived at
the conclusion that the markings on diatoms were in fact due to the
presence of hemispherical elevations or bosses. Fresh attention was
drawn to this view by the paper of the Rev. J. B. Reade “On the
Diatom Prism and the true form of Diatom Markings.”* Mr. Reade
appears to have attributed to his Diatom prism (which I have care-
fully tried), just as Dr. Pigott has to his “ Aplanatic Searcher,” the
superior definition, which is, in reality, ascribable to the improved
quality of the objectives, and especially of the immersion objectives
recently produced by certain makers. In point of fact, with modern
immersion objectives, and especially with the immersion {th and +,th
of Powell and Lealand, I find myself able to produce better effects
with the help of an achromatic condenser, properly managed, than
by the Diatom prism.

More important even than the paper of Mr. Reade, however,
were the experiments of Schultze on artificial diatoms, to which
Mr. H. J. Slack has recently drawn attention in his paper “ On the
Patterns of Artificial Diatoms.”t I have never experimented with
these, but have in my possession a number of photographs of them,
presented by my friend Dr. Maddox, which are of the most in-
structive character. That this view of the structure of diatoms is
substantially correct I do not now doubt. The details in the case of
each individual diatom will, however, require careful study.

No. XI. Photograph of Plewrosigma Formosum; 4500
diameters.

No. XII. Photograph of the same; 3100 diameters—The
* “Monthly Microscopical Journal,’ vol. ii., p. 4. ft Ib., vol. iv., p. 181.

160 Transactions of the

beading of this diatom is well described by Mr. Reade (loc. cit.).
I have never been able to see the six black dots surrounding each °
bead, mentioned by Dr. Pigott.

No. XIII. Photograph of Coscinodiscus ; 1100 diameters.—This
photograph shows the spherical bosses well. It is apparently an
undeveloped frustule. On one side the hemispheres are quite a
little distance apart. On the other side they are crowded together,
producing the spurious appearance of a hexagonal framework with
little spherical beads at the corners.

No. XIV. Photograph of Plewrosigma angulatum, showing
beads; 3100 diameters.

No. XV. The same; 4500 diameters.—In these pictures the
illumination has been so managed as to give a considerable degree
of perspective to the markings. For comparison, I append a
print showing the appearances produced by more central illumina-
tion, vz. :—

No. XVI. Photograph of Pleurosigma angulatum; 3000
diameters.

I conclude this paper with some brief remarks on two difficult
diatoms which have been the subject of much recent discussion,
viz. the Surirella gemma and the Amphipleura pellucida.

In the case of the Swrirella gemma, Hartnack, whose original
description I have not yet seen, observed fine longitudinal striz in
addition to the fine transverse ones, previously known to exist
between the large transverse ribs. He supposed the true markings
to have the form of elongated hexagons. These are figured by
Dr. Carpenter* and by Frey.tj ‘The mean length of this diatom is
given in the ‘ Micrographic Dictionary’ (second edition) as 349th of
an inch. A careful examination of specimens mounted dry, has
satisfied me that Hartnack’s interpretation is erroneous. The fine
strie are, I think, rows of minute hemispherical beads, and the
appearance of hexagons is the optical result of imperfect definition
or of unsuitable illumination. For photographing this object, I
have selected a frustule of somewhat less than the medium size. It
measures z}pth of an inch in length. Longitudinally, the fine
strie count at the rate of 72,000 to the inch. These striz are
resolved into beaded appearances which count laterally 84,000
to the inch.

No. XVII. Photograph of Surirella gemma; 3100 diameters.
(Portions of two frustules.)

No. XVIII. Photograph of the same; 1034 diameters. (Two
frustules and portions of a third.)

Finally, with regard to the Amphipleura pellucida or Navicula
acus. ‘The striz on this diatom were first described by Messrs.

* ¢The Microscope and its Revelations,’ 4th edition, p. 182.
+ ‘Das Mikroskop,’ 3rd edition, p. 40.

Royal Microscopical Society. 161

Harrison and Sollitt, and were estimated by them at from 120,000
to 130,000 to the inch. These measurements have been adopted in
the ‘ Micrographic Dictionary,’ and by most of the English writers.
Dr. Carpenter and Dr. Pigott are exceptions. Dr. Carpenter has
“not been able to satisfy himself, however, of the correctness of
Mr. Sollitt’s estimate of the distance of the striz, and is still disposed
to regard it as too high.”* Dr. Pigott on the other hand makes
them as fine as 150,000 to the inch.

Of the American observers, Messrs. Sullivant and Wormley
failed to make out the striae, but this was ten years ago.t

A few months since I received from Messrs. Powell and Lealand
a special stage with a small hemispherical condenser, contrived for
the purpose of showing the lines on this test. I ultimately found,
however, that a pencil of monochromatic light converged by an
achromatic condenser of high angle gave better results, provided the
condenser was thrown somewhat out of the optical axis of the mstru-
ment so as to secure sufficient obliquity. With such illumination,
the immersion -{;th of Powell and Lealand resolved the smallest
frustules ; the immersion 3th of the same makers resolved the coarser
ones, but was not adequate to resolve the finer.

The best mounted specimens at my disposal were furnished by
Messrs. Powell and Lealand a few months since. They wrote me
they were not able to obtain cleaner samples at the time. The
frustules are dry and are adherent to the lower surface of the thin
glass cover, which was disfigured by fine débris, as is only too
plainly shown in the photographs, though these were taken from
the cleanest portion of the slides. The photographs show the trans-
verse markings on the frustules as fine, somewhat beaded, striz.
The analogy of other diatoms justifies the presumption that Dr.
Pigott is right in speaking of these strie as rows of beads. I was
not able, however, to make them out as separate beads on the
specimens at my disposal. Whenever I can procure some clean
frustules, mounted on a thin cover and with thin underglass, I will
try what I can do further. Meantime I should be glad to learn
how nearly the appearances I have photographed correspond with
what is actually seen by those English observers who are most
familiar with this test.

On one point, however, I have no doubt, namely, the distance of
the beaded strize from centre to centre. As Dr. Carpenter correctly
thinks, this has been set down at too small a figure. In fact, there
exists in many quarters a disposition to underrate the actual size of
many minute objects, which is to my mind a convincing proof of
the very imperfect manner in which these must have been seen.
For measurement, with at least approximate accuracy, offers no

* <The Microscope and its Revelations,’ 4th edition, p. 182, note.
+ ‘American Journal of Science and Arts, yol. xxxi., p. 12, 1861.

162 Transactions of the

practical difficulties in the case of those objects which can be dis-
tinctly observed. Dr. Pigott seems to have fallen into this error
with regard to other objects than Amphipleura pellucida. Thus
for example, he says :*—“ It will be extremely interesting to hear
that our American brothers can resolve the strize of known diatoms,
haying them arranged from 120,000 to 150,000 lines to the inch.”
This is a rather sweeping statement, and in the absence of a list of
the “known diatoms” whose strie are estimated at this figure,
I will confine -my remarks to the Amphipleura pellucida. Prichard
states the length of this diatom at from 14th to 3$oth of an inch.
The ‘ Micrographic Dictionary’ gives the mean length at 0044. The
frustules on the two slides sent me by Powell and Lealand measured
from +4;th to z4oth of an inch.

From a number of negatives, I send prints of two.

No. XIX. Photograph of Amphiplewra pellucida; 960 dia-
meters. Frustule ;ioth of an inch long.

No. XX. Another view of the same frustule ; same power.

After making the photographs, I carefully counted the strie,
both on the glass negatives and in the microscope. The frustule
selected for the above photographs counted 91 strie to the
thousandth of an inch. Larger frustules exhibited rather coarser,
smaller ones rather finer striez. On the smallest frustules at my
disposal, several of them only 35th of an inch in length, I found
no example in which the number of striz exceeded 100 to the
thousandth of an inch. ‘The strie of these smallest frustules do
not then rival in fineness the nineteenth band of the Nobert’s plate,
the study of which I am convinced will make those microscopists
who are able to resolve it more careful in their “estimates,” with
regard to the striz of diatoms.

In conclusion, I have to add, simply, that all the photographs
forwarded with this paper were taken by the immersion yth of
Powell and Lealand, with the exception of the Coscinodiscus, for
which I employed the immersion 3th of the same makers.

Note.—Since writing the foregomg my attention has been
directed to the letter of Mr. Lobb,t from which it would appear
that Mr. Lealand, of the firm of Powell and Lealand, “has suc-
ceeded in counting the Amphipleura lines, and finds them 100 in
tooth of an inch.” -This agrees perfectly with my own results
on the smallest frustules. 1 am happy to find that my testimony
against the extravagant “estimates” which have been published, is
corroborated by such a witness.

[Plates LX XIX. and LX XX. contain selections from the photo-
graphs sent to the Society by Dr. Woodward.—Ed. M. M. J.

* ‘Monthly Microscopical Journal,’ vol. iii., p. 311. + Ib., vol. iii., p. 104.

e @eleterens

x gs

Suwrurella,

x

° Pleurosigma, Horm

Gemma

Royal Microscopical Society. . 163

IIl.—Microscopical Examination of Water for Domestic Use.
By James Betz, F.C.S.

(Read before the Roya Mricroscorican Socirery, March 1, 1871.)

Tux microscopical examination of water for domestic use is, in my
opinion, a suitable subject to bring before this Society. The
subject is essentially a practical one, and affords a wide field in
which microscopists might occasionally spend a portion of their
time with much profit.

A sample of water which is largely contaminated with sewage,
exhibits, when placed for a few days in a warm chamber, such a
mass and’ variety of life, that the mind is almost bewildered in
trying to master in detail the numerous creatures that have sprung
into existence within so short a space of time. From the diversity
of the ingredients usually composing sewage, it would, indeed, be
difficult to find a mixture so well adapted for the development of a
variety of organisms.

Mr. Heisch was, I believe, the first who attempted to point out
a possible means of detecting, by the use of the microscope, whether
water had been contaminated with sewage or not; his method
being founded upon the development therein of a distinctive
organism in the presence of sugar. |

He found that when a’small proportion of pure cane-sugar was
added to water containing sewage, and the mixture was maintained
at a temperature between 60° and 70° Fahr., and placed in a posi-
tion where plenty of light was admitted to the bottle in which the
liquid was contained, the mixture became turbid in times, varying
from twenty-four to sixty hours, and contained cells and a delicate
fungus mycelium, followed by the ultimate development of the
odour of butyric acid. From this, Mr. Heisch concluded that
sewage contained particular germs, which when brought into
contact with sugar in water immediately began to grow.

This observation was necessarily regarded as a most important
one, not only because it promised to effect a change in the present
mode of determining the presence of sewage in water; but to lead
to the discovery and identification of the germs which generate
epidemics.

Mr. Heisch deserves great credit for initiating such an im-
portant line of investigation, and the combined researches of micro-
scopists on the subject may ultimately lead to important practical
results with respect to the laws of health, by determining the
exact conditions under which the germs of various organisms are
developed.

Shortly after the subject was brought before the Chemical

VOL. V. . N

164 Transactions of the

Society, I had occasion to assist at the examination of a sample of
water obtained from a well in the neighbourhood of Drury Lane,
and suspected to contain impurities. ‘Toa portion of the water Mr.
Lewin added a small quantity of pure cane-sugar, and in less than
twenty hours the mixture became turbid, and the liquid when
submitted to a microscopical examination was found to be literally
alive with minute bacterian-like bodies in an extremely active
condition; and it was obvious that these little organisms by their
action on the cane-sugar were the immediate cause of the turbidity.
The water was bright, and there was certainly nothing in its ap-
pearance to cause any suspicion that it was contaminated with
sewage. Subsequently it was ascertained that the drain-pipes of
an urinal not far from the well were stopped up, and that the earth
around the well was saturated with urine. On being informed of
this fact, and recollecting that the characteristic fungus mycelium
had not been observed when the water was submitted to the sugar
test, I made various experiments with mixtures of urine, in different
stages of decomposition, and New River water, and in every instance
failed to discover any distinctive fungus mycelium, the field being
almost exclusively occupied by bacterian bodies.

About six weeks after this I accidentally made the observation
that water which had been passed through animal charcoal became
turbid when submitted to the sugar test, and that a large develop-
ment of bacterian bodies was produced. I had purchased a new
charcoal filter in the month of September last, and I was naturally led
to try the water by the sugar test before and after filtration, when to
my surprise I found that the filtered water became turbid, while
that which had not been filtered remained bright. This result at
first puzzled me, but as I had observed last summer, during the
course of my experiments on fungi, that phosphate of lime exercised
powerful deteriorating properties by promoting the development of
organisms, I was led to attribute the presence of the bacteria in
the water after filtration to the action in some way of the phosphate
of lime in the animal charcoal. The mystery of this action of the
animal charcoal has since been explained, as it is known to be a fact
that a portion of the phosphate of lime in the charcoal is dissolved
out by the water when passing through it.

I have made some special experiments with phosphates in pure
distilled water, under various conditions, and the results showed
that in every case when phosphate of lime was present, the liquid,
on the addition of cane-sugar thereto, became turbid and literally
alive with bacteria, in times varying from twelve to thirty hours.
The phosphates of the alkalies gave negative results, but when nitrate
of ammonia was present, a slight turbidity occurred after the lapse
of several days, and the liquid was found to contain a few bacteria.
The results of these experiments confirmed my previous observa-

Royal Microscopical Society. 165

tions, that the phosphate of lime possessed powerfully stimulating
properties in promoting the development of organisms. The phos-
phates of the alkalies, however, in the presence of pure vegetable
albumen, also promote the development of organisms, and produce
turbidity in cane-sugar solutions,

I also made various experiments with water passed through
animal charcoal, and with water to which animal charcoal had been
added, and in every instance when sugar was added, and the mix-
ture placed in a chamber maintained at a temperature between 60°
and 70° Fahr., the sample became turbid, in times varying from
twelve to forty hours.

I have since observed that animal charcoal which has been
in use for a considerable length of time ceases to possess the pro-
perty of imparting to the water the power of producing turbidity
on the addition of sugar; doubtless from all the phosphate of lime
having been dissolved out by the long and constant action of the
water.

Hitherto in the course of my experiments both with phos-
phates and urine I failed to obtain any characteristic mycelium ;
but it occurred to me that so long as the field was occupied by such
a mass of bacterian bodies, there was but a small chance of obtain-
ing the development of any other organisms, and as I had observed
that the greater the proportion of urine or phosphate of lime pre-
sent in the water, the water not only became turbid within a
shorter time, but the bacterian bodies were greatly increased in
number.

To obviate this I experimented with more dilute solutions. I
first made an experiment with one drop of fresh urine in 20 ounces
of New River water, and the result was completely successful, and
I obtained an exquisitely beautiful filamentous development corre-
sponding to the characteristic mycelium described.

Now I had observed that the bacterian bodies produced in New
River water, when a phosphate was present, were identical in appear:
ance and character with those which were produced by the addition
of fresh urine to a portion of the same water, and it was difficult
to comprehend how, when fresh urine was used, one class of the
organisms developed corresponded with those produced in the pre-
sence of phosphate ef lime, while the filament was absent.

To try and assimilate more the conditions of making the experi-
* ments with. a phosphate and the urine, I added very minute
quantities of phosphate of potash to New River water—from two
to five hundredths of a grain to 40 ownces—and with this pro-
portion of phosphate a beautiful filamentous development similar to
that which was produced by the one drop of urine, made its ap-
pearance, thus clearly indicating that phosphate of lime exercised an
_ Important part in causing the development.
nN 2

166 Transactions of the

I next largely diluted some water that had been filtered through
animal charcoal, and subjected a portion of the mixture of filtered
and unfiltered water to the sugar test, when an abundance of fine
filaments was developed. ‘These filaments were not identical with
those produced in the presence of urine; but the difference was
probably due to my not having arrived at the proper conditions.

From what has been stated it will be seen how easily by aslight
change of conditions the line of development of living things may
be modified, and this is one of the great difficulties to be contended
with in attempting to establish whether a water is impure or not,
from the development therein of any particular organism; and it is
even possible for a water under certain conditions to contain com-
bined nitrogen without producing, when submitted to the sugar test,
any turbidity.

Dr. Frankland, whose researches on this subject are full of
interest, was the first to make the observation that effluent sewage
water, when passed through a thick bed of gravel, was deprived of
its phosphates, and that although containing combined nitrogen, the
water, when submitted to the sugar test, remained bright.

I was unsuccessful until within the last few days in obtaining any
filamental growth from vegetable albumen approaching in appear-
ance the filaments that occur in water containmg sewage. A small
quantity of partially purified vegetable albumen was introduced into
New River water contained in an open glass vessel and left for nine
days, at the expiration of which time the water contained filaments,
both in strings and fragments, the latter being almost undistinguish-
able from those found in effluent sewage waters. |

While making the experiments with urine and phosphates I
also made many with sewage and effluent sewage water under
various conditions. There happens to be near me a farm on which
the sewage of Epsom is utilized, and I obtained various samples of
the sewage as it entered the farm, and of the effluent sewage water,
and also samples of the latter after it had become mixed with the
water of a brook.

In dealing with such samples as these in their normal condition,
and examining them microscopically from time to time, the first
thing that strikes an observer is their capability of producing a great
variety of life without the addition of sugar or any extraneous sub-
stance, and when, after various degrees of dilution, the samples are
submitted to the sugar test, they become less or more turbid, and
contain variable proportions of fine filaments and bacterian bodies.

In effluent sewage water, I have rarely met with the filaments
in that beautiful network form in which they are found in water
containing only urine or a phosphate; but there is no difficulty in
deciding that both filaments belong to the same class of growth.

The filaments met with are of at least two sizes; one is so fine

Royal Microscopical Society. 167

that the jomts cannot be seen when magnified 1000 diameters.
The joints in the other filament can be observed when magnified
about 400 diameters. Both descriptions of filaments are found in
water containing sewage, but in some diluted samples of effluent
sewage water I have only been able to discover the finer filaments,
while in others only the larger. In mixtures of urine or of a
minute quantity of alkaline phosphate with New River water, the
larger filaments are found, and they occur in the network form.

Both filaments soon break into pieces of various lengths and
diffuse themselves throughout the liquid. In the case. of the
filament produced in the water containing urine, I observed that
in its earlier stages of development the filament appeared to be
surrounded by a sort of soft casing, which gradually separated
from the filament, the jointed character of which was then readily
distinguishable.

While dealing with the subject, it is proper to point out that
when some descriptions of ditch and other dirty water are submitted
to the test, filaments similar in character are developed, and after
these break up and become diffused throughout the liquid, they
are hardly distinguishable from those produced in water containing
sewage ; in fact the only difference apparently observable is that the
broken filaments are much less numerous than in samples of effluent
sewage waters, which undoubtedly produce the filamentous growths
in great abundance. ‘The dirty waters upon which I operated
became turbid, and were found to contain bacterian bodies.

The rapid growth of the filaments in the presence of phosphate
of lime and cane-sugar is very curious and interesting, and the
interest in their development is somewhat heightened by the fact
that the filaments will, I think, be found to belong to a higher
order of vegetation than fungi, viz. to the Algz and probably to
the class Oscillatoriaceze.

' In samples of water containing sewage a large proportion of
the bacterian-like bodies partake more of the character of vibrios
than the corresponding organisms in water containing phosphate of
lime, and free from organic matter; but the line of distinction is so
fine that I could not undertake at present to define the difference.
Those bacterian bodies which are produced in water containing a
large proportion of sewage, and especially urinary sewage, appear
to be more flexible than those developed in the presence of sugar
in effluent sewage water, or in water containing phosphate of lime
only. The most active condition in which they are found, is when
they consist apparently of two cells or divisions, and in this form
they are extremely rapid in their motions, and are seen darting
constantly across the field, and occasionally stopping and performing
a revolving motion. I cannot help thinking that these bodies,
which multiply with such extreme rapidity and produce such rapid

168 Transactions of the

changes in solutions of organic matter, are a dangerous form of
organism to be taken into the human system.

Finally, the results of my experiments are in accordance with
the theory, now almost universally accepted, of the general diffusion
of germs; and once a suitable soil is produced for any class of
these germs they will soon find it out and begin to grow, just as
bacterian bodies develop in New River water immediately after a
small proportion is added thereto of phosphate of potash and cane-
sugar respectively.

Iil.—On the Winter Habits of the Rotatoria.
By Cuartes Cusirt, C.E., F.R.MS.

(Read before the Royau Microscopicay Society, March 1, 1871.)
Puate LXXXI,.

Every step we take in the investigation of the habits and functions
of this interesting Class of the animal kingdom leads us to the con-
clusion that while a reliable classification is still wanting, facts are
being daily established on many hitherto doubtful points in their
economy which are tending towards the establishment of a reliable
basis for such a desirable end.

I have for some successive winter seasons directed my attention
to these particulars as far as the tube-builders are concerned; and
as it appears from the published records of kindred societies that
much misapprehension still obtains on certain points in the eco-
nomy of this interesting CLASS, I beg leave to preface the consi-
' deration of the subject proper by a few prelusory remarks on the
points in question.

It will consequently be necessary for our purpose to distinguish
the members of the Loricated Families of SECTION I. of the
CLASS ROTATORIA of Ehrenberg’s SYSTEM under two Drv1-
sions,—the Sonrrary Fixep, which include Melicerta, Limnias,
(:eistes, Tubicolaria, Stephanoceros, and Floscularia; and the
CiusrereD Tree, which contain only Lacinularia and Conochilus ;
for while these disagree in points of habit they are identical in an
important point in their anatomy, which by careful and persistent
investigation I have proved and recorded.* They, one and all,
whether ciliated or setigerous, possess a secondary range of vibra-
tile cilia situated anteriorly to the mouth, the marginal wreath
being constituted to act as a foraging organ, in collecting a hetero-
geneous mass of particles about the disk; but the secondary range,
acting in conjunction with certain ciliated lobular process, exercise
a discriminating function in selecting from the heterogeneous mass,

* ‘M. M. Journal,’ May, 1870.

Royal Microscopical Soccety. 169

and in separating therefrom, and severally disposing of the particles
so selected for alimentary or building purposes, and in rejecting
others for the time being, which are brought again and again under
the influence of the marginal wreath by means of the cements which
that creates.

Dujardin’s classification embraces each of the members of the
foregoing Division, both Fixep and F res, but it includes a form
which is not loricated, viz. Ptygura; this, however, could not be
admitted, as its identity as a mature animal is doubtful.

We find, however, that abnormal conditions obtain with certain
members of the Sonirary Fixep Drvistoy, which normally are
permanently attached, particular instances occurring in respect to
Floscularia and Cicistes, which under such conditions occasionally
forsake their first-selected habitats, and resort to foreign ground,
where they re-establish themselves, and construct anew their so-
called lorications, stmply gelatinous or floccose, according to their
respective characters; but whether these abnormal conditions are
accidental or natural I have some hesitation in declaring ; I consider
it, however, worthy of note, for we shall see as we proceed that
such a capacity in these forms associates them closer than hitherto
acknowledged with certain members of SECTION II.

Each individual of the Firxep Drviston is furnished with two
setigerous antenna, situated bilaterally, but not diametrically oppo-
site ; hence the great difficulty in arranging animals for observation
precisely in such a position that they can be viewed without the
interposition of some other part of the body, and not even then
with inferior appliances, either mechanical or optical; but with
good apparatus and patient application they are to be found in one
and all: they are clearly apparent in F’. coronetta (mhz), as also in
Stephanoceros, and familar to all observers in Melicerta. It must
therefore be distinctly understood and accepted that no Rotifer
exhibiting a single setigerous antenna can be admitted as a member
of the Fixrp or of the Frex Drviston of the Loricated Families of
the Roraroria.

It now becomes necessary to distinguish certain members of
SECTION II. of the CLASS ROTATORIA, the so-called Mlori-
cated Family Pumopinma, which by their peculiar habits and
structure form a connecting link, hitherto unrecognized between
this Family and those of SECTION I. previously referred to; for
our present purpose, therefore, we must separate these also into
two Drvistons, which may be designated the 'TpmporaRILy F'Ixep
and the AzsorureLy Frees, this last being only represented by
Hydrias, Typhlina, and Monolabis, which under « new classification
should be included with the numerous members of the following
Families,—Hydaliniea, Euclanidota, and Brachionea, the Flexible
Creepers of Gosse.

170 Transactions of the

Now, this Temporarmy Frxep Drviston is represented by
Callidina, Rotifer, Actinurus, and Philodina, which though
nominally FREE are specially organized to permit them to assume
at will, either a FREE or a Fixep position, and of maintaining these ,
positions respectively for periods of indefinite extent. The foot of
each individual of this Drviston is furnished with a sucker extending
beyond the toes of the telescopic footstalk, which together constitute
a mechanical support that may be exercised or released at will.

This Temporarity Frxep Drviston, while it assimilates through
certain members of SECTION I. by reason of the vagrant habits
of the foscules already referred to, differs, moreover, still further
from the AnsonuTELY Free Drvision in one most important par-
ticular, viz. the possession of a single setigerous antenna which
distinctly removes it not only from the Free Division possessing no
such appendage, but furthermore from the Soxrrary Frxep forms
of SECTION IL, which possess unexceptionally two antenna; so
that the pseudo genus Cephalosiphon with its specific title Limnias
of Ehrenberg’s Classification (Plate LXXX1., Figs. 1 and 2), should
not be admitted into the Family in which it is unwittingly placed.
It belongs indisputably to this Tremporarity Firxep Drvision, and
is generically a Philodine under conditions which at first might
appear abnormal, but which prove on a more intimate acquaintance
to be natural functions.

The Philodines, moreover, are provided not only with the
secondary range of cilia which characterize the Frxep Drviston, but
also with a ciliated rudimentary pellect-cup im conjunction, which
they employ in building a floccose covermg round about them, and
this conclusively associates them with this Division. With regard,
however, to the remaining members of the Fammy Pumopinma
according to this proposed Division, I am not at this time prepared
to speak, and can only suggest it as a point for investigation worthy
of the attention of my fellow-workers.

I have had numerous examples under observation throughout
the winter months for some years past, having broken the ice to
obtain them. Placed in a cool situation, they invariably remained
some hours and even days in this completely loricated condition ;
but as the warmth of the room, and-that of the lamp while under
observation, began to be appreciated, palpable movements were first
manifested within the floccose covering, the orifice of which is
closed by a coalescence of the materials composing it, such as de-
scribed by Mr. Henry Davis, in reference to Cicistes longicornis :
they eventually, after shorter or longer periods of repose, wriggled
out of these temporary dwellings, declared themselves bona fide
Philodines, and swam freely and buoyantly around the field,
exhibiting distinctly their bilobed rotary organs, supplemented with
the secondary range of appropriating cilia, with the conspicuous

onthe Monthly Microscopical Journal April 1.1871 PL LXXX,

Pee

“of

CEPHALOSIPHON Limmnics
(Pseudo Species) ; he

WAL cornuta. go
Vee of

ma

fs

Vy, Flosculartia$

CGubitt del?

Winter Habits of the Rotatoria «100.

Royal Microscopical Society. 171

single setigerous antenna, practising as is found on closer exami-
nation an incessant protrusion and retraction, and thus manifest-
ing the same general construction as that so lucidly described by
Professor Williamson in his elaborate description of Melicerta
ringens in 1853, and it is seen in the instance of Philodine
that when the tentacle is protruded it is terminated by a tuft of
fine divergent setee (Plate LXXXI., Fig. 3), implanted on a pear-
shaped body, “ from the under-side of which there proceeds a delicate
muscular band” which in contracting draws this pear-shaped body
downwards, thus inverting the extremity of the tube, and forming a
double sheath protecting the sete (Fig. 4). And such I must submit
to the process followed in the instance of CZ. longicornis. It is
opposed to the facts of animal physiology that a vascular structure
like the tube, should support a palpable diaphragm pierced with an
orifice presenting a sharp edge such as would result from drilling a
hole in a metal plate. .

From the opportunities I have had of examining many examples
of the building propensities of the genus Philodina, 1 can confi-
dently assert that these temporary dwellings are more frequently
of the consistent form shown by Fig. 5, with the enclosed occupant
indistinctly indicated, and in outline by Fig. 6, which is offered as
a portrait of this vagrant occupier in her expanded condition ; and
I am prepared to affirm that these forms do not abstain altogether
from this habit of building, even during the warmer months; they
perform the same operations under conditions of greater activity,
not remaining on one spot for periods of sufficient duration to perfect
the work, as shown by Fig. 5, but only to produce effects similar to
those shown by Figs. 1 and 2, which are reproductions of Mr.
Tatem’s sketches.

The Floscules also give conclusive evidence of this adoption of a
winter protection. I find numerous instances of every species in
which they have invariably selected the fork of the weed for the
purpose, affording as it does additional security and stability for
such a retreat. The inhabitants are generally accompanied by
several eggs, and these, from the effects of the artificial warmth of a
living room, are rapidly hatched, two or three at one time being
frequently seen struggling for ascendency to attain freedom, so that
I have had a numerous juvenile population of F. cornuta, which
species happens this year to predominate in my collections. I have
consequently selected this charming little creature, with its ova and
family, as an appropriate illustration of a Floscule in its winter habi-
tation, through which it has emerged under the effects of artificial
warmth (Fig. 7).

This same class of protection is adopted by F’. campanulata and
F. ornata to a proportionate extent ; and my new species, F coro-
netta, which is the most sensitive and timid of them all, carries out

172 Transactions of the

this earthwork system to a much greater extent proportionately
with its size. Stephanoceros takes similar precautions, though on
the other hand inversely proportionate with its creased dimen-
sions in comparison with its smaller compeers. Melicerta and
Limmas simply draw a mass of flocculent particles into the mouths
of their tubes.

There obtains amongst the Floscules a particular member, and so
far as I am informed is nameless, with which I have had similar
evidence of its winter habitation. It is somewhat rare, and is
smaller than any one of the other members. The first specimen
that came under my notice gave me the erroneous impression, from
the undeveloped disk, the almost total absence of sete, and its
diminutive proportions, that this was the male, as I had on the
first occasion failed to notice any ova either deposited or contained
in what proved subsequently to be the ovary and not the testes
as I had at first assumed, the contained matrix of finely granulate
matter exhibiting on higher magnification the well-known nucleated
nuclei. It is needless to add that they soon declared themselves in
their true nature, by collecting at the foot from three to five fully-
developed ova, as shown by Fig. 8.

It is satisfactory to find corroborative evidence in support of
these views on the winter habits of the Rotatoria from facts which
have lately been brought to light, showimg that reverse conditions
produce adverse effects—Mr. Chantrell, of the Liverpool Micro-
scopical Society, having recorded instances in which with the Flos-
culariz found in the Windsor ponds which contain warm water,
that “the tubes disappear in the mature animals.” This statement
in its entirety must, however, be received with due caution, for,
unable to detect the secondary wreath of cilia on the lobes of the
tube dwellers, which is an indispensable attribute in their special
organization, he may, with the same appliances, optical or mecha-
nical, be equally incompetent to detect the transparent tubes, which,
while devoid of foreign accessions, may nevertheless be present.

Royal Microscopical Society. 173

IV.—The Magnifying Power of the Microscope.
By Count Castracave.

“ Surirella gemma may truly be called a touchstone for a high-power
objective. I do not think that it has been clearly defined as yet.’—
Joun Mayan, ‘Q. J. M.S8.,’ July, 1869.

The following paper, which I have just received from Fano (Italy),
will answer, I hope satisfactorily, the above-quoted remark. It is an
original, yet unpublished, MS. of Count Castracane. I did my best
to translate it faithfully from the Italian. That being my native
language, it may easily be presumed I understood it right enough,
though it might be a quite different case with my not home-made
English. However, the benevolent reader will easily overlook any
un-English phrase for the sake of the valuable matter.

P. J. GAGLIARDI.

Count CASTRACANE’S PAPER.

(Read before the Royat Microscopican Society, March 1, 1871.)

Far from wishing to sit down as judge on the controversy, which
lately sprung up between the illustrious American micrographer,
Charles Stodder, and Dr. Hagen, of Cambridge College, U.S., about
American microscopes and their respective value, I simply beg to
offer them some suggestions, whilst I shall bring forward a few
facts, wherewith I am perfectly acquainted by my own experience ;
these I hope will serve, better than any other argument, to clear
up the mooted question.

Mr. Stodder* maintains against Dr. Hagen:—1. That the
Surirella gemma given by Hartnack with flat hexagonal markings
is simply a theoretical diagram of the said diatom. 2. That the
hexagons were not probably seen, but with Tolles’ ~,th by Mr.
Bicknell. 3. That Mr. Hartnack himself did not see those
hexagons but with his No. 10 (,';th), and did not succeed in show-
ing it to more than two distinguished micrographers. 4. That Dr.
Kulenstein failed to see those hexagons with Nos. 10, 11, and 12,
nay, even with the best of Ross, and the most powerfully con-
structed up to this time, the th of Powell and Lealand.

In regard to the Surirella represented by Mr. Hartnack, in
his special memoir on this subject, with oblong hexagons (oblong
I think is a more exact expression in this case, than flat), I may
say that since the 7th March, 1869, I had myself the occasion of
treating this subject, in a short memoir, where I tried to set right
what I deemed wrong. ‘There, speaking of the difference between

* See ‘Monthly Microscopical Journal, Nov., 1870.

t See ‘Atti dell’ Academia dei Nuovi Lincei,’ §iv. Su l’uso delle Linee
dr Nobert, ete.

174 Transactions of the

preparations made on balsam and without it, I observed that in the
first case the stvix, or better, the longitudinal divisions of S. gemma,
when observed in an oblique, monochromatic light, present a
wicker-basket texture, and make us believe that Hartnack was
right when he interpreted and sketched them like oblong hexagons.
But in the second case in which, for Moller’s test-plate prepared on
balsam, I substituted dry shells, simply covered with a thin glass,
they presented immediately nice moniliform striz, or rows of small
spheroids, so disposed, that the polar axis of each of them was equal
to rds of the equatorial. I may add, moreover, that, although the
difficulty of distinguishing the most minute particularities of a
diatom prepared on balsam be far greater than that of seeing it in
its dry condition, I did even succeed, after a little pain and trouble,
in perfectly making out the spheroids in Moller’s own preparation.
And more than that, under a properly arranged monochromatic
light, their appearance did turn out so evidently clear, as to leave
not the least doubt or perplexity about the right interpretation of
such wonderfully minute details. This I could not see perfectly
till late, except with’a good No. 10, of Hartnack; but this year
I obtained the very same result with another No. 10, which Mr.
Nachet was kind enough to construct purposely for my trial.

The nature and form of the structural details of that interesting
diatom being thus set aright, it is plain at the same time that Mr.
Bicknell was not the only one who could witness the structural
features of the Swrirella in question. His perception, besides,
haying been not quite true to the fact, though his shortcoming was
very excusable, as some of the most distinguished micrographers
were liable to the same mistake for several years, taking for hexa-
gonal the spheric markings of Plewrosigma angulatum. I had
thought so myself at first, decerved by imperfect photographs, and
backed, as I was, by the authority of first-rate micrographers who
had preceded me in such trials. But I was soon put right, first by
better photographs, which I obtained more clear ‘and accurate with
the exquisite ' objective of C. Zeiss, of Jena; and then again by
wonderfully increasing powers which Colonel Woodward was kind
enough to send me, for which I publicly express my gratitude,
waiting the first opportunity to return it by some of the best photo-
graphs of my own collection.

Thus my successful studies were happily performed by means
of Hartnack and Nachet’s No. 10. Yet whoever does make use of
these valuable objectives with a simply white light cannot expect to
obtain more than the mentioned wicker-basket appearance, not the
precisely moniliform structure of Swrdrella gemma. More than
once Hartnack himself showed me the said diatom under this sort
of light, not only with his No. 10, but even with Nos. 9 and 8,
holding as his private opinion that with his 7 merely he might have

Royal Microscopical Society. 175

had the same result. After this I can hardly understand how Mr.
Hartnack, so skilful as he is in managing his own objectives, and so
familiar with the diatom in question, could have failed to show two
distinguished micrographers the very same details, unless we assume
that one person’s eye is more apt than another to descry such
utterly minute features.

Neither could I think otherwise in regard of Stodder’s assertion
that the most distinguished German diatomologist, Dr. T. Eulen-
stein, failed in making out the same details with Hartnack’s Nos.
10, 11, and 12; nay, with the strongest objectives of Ross, even
with the highest at present known, the wonderful th of Powell
and Lealand. Such negative result does evidently contrast with
my own experience. If it might not be pleaded that more urgent
business perhaps prevented the great microscopist from giving his
precious time to the troublesome and not very easy task of examin-
ing so finely minute structures, which, though they do not consi-
derably advance our diatomological science, have certainly a great
importance for testing the relative value of our microscopes; the
increasing power of which prompts us to even more delicate re-
searches, by which the sphere of our knowledge is more and more
enlarged.

On this subject I read in the Monthly Microscopical Journal
(Nov., 1870) that the illustrious Professor Huxley, at the meeting
of the R. M.8. (Oct. 12 that year), lamented the actual insufficiency
of our microscopes for histological researches, saying that “ practically
the nature of the question just now is whether, in an organic tissue,
one could truly define a point not more than spdooth of an inch in
diameter ;” adding again, “ Histologists, I fear, are at the end of
their work unless .... they could obtain microscopes which would
enable them to separate two points the 100,000th of an inch apart.”

To this I might confidently answer that what the illustrious
Professor thinks to be future has been attained already. In proof
that this is no vain presumption of mine, I adduce the following
reasoning :— Whoever takes any interest in the improvements which
are daily made in the microscope will surely have read of the various
articles and memoirs that, during these last three years particularly,
have been published in both the Quarterly and Monthly Micro-
scopical Journals by the most active and zealous microscopists.
Nobert’s wonderful incisions upon a glass plate, disposed in thirty
graduated bands, till the last reaches 344th of a millimétre apart,
seemed at the beginning to baffle the highest powers of the most
perfect microscopes. Yet at the very beginning of 1867 I had the
satisfaction of resolving those minute striz to the very last. I know
that Mr. Nobert, after he heard that the microscope had met his
challenge, increased his divisions till he reached the z)ysth. I
have not had the opportunity of putting my microscope to this new

176 Transactions of the

test, though I feel confident to reach it also. However, we have
heard that in America Drs. Woodward and Curtis did already suc-
ceed in resolving those minutissime strix; and to prove that what
they have seen was no delusion or hallucination, they have got
exact photographs of them, copies of which they sent over to
Europe.

After this, I think we may safely assert that, even as it is now,
the microscope has fairly reached—nay, we might say has passed—
the line which Professor Huxley deemed indispensable for his histo-
logical purpose.

Another proof I might adduce in confirmation of what I have
stated—that is a photograph, which I have obtained last year, of
Amphipleura pellucida, out of Moéller’s graduated test-plate, not-
withstanding the difficulties which attended that preparation on
balsam. Unfortunately my negative was blurred and rather faintish,
so that it could not give good positive images. Nevertheless, the
strie are there so finely and so distinctly drawn out, that they may
be perceived clearly enough, though the magnifying power of the
microscope was not higher than 640 diameters. The matrix gives
without any doubt 4000 in a millimetre, which answers completely
Huxley’s desideratum of one hundred thousandth of an inch. It
was Hartnack’s No. 10 that gave me at first that photograph, the
illumination being taken from a decomposed sunbeam. But I had
afterwards the same result with the same number of Nachet; both,
doubtless, first-rate objectives, since they stood the most difficult
trials. However, as I am desirous to advance scientific inquiries,
rather than to boast of my own instruments, I dare say that, should —
Professor Huxley or any other student of the secrets of nature, try
the same thing with microscopes of the best make, either European
or American, using the same precautions which I did, they would -
hardly fail to obtain the very same results.

My practice is this: whenever I want to make out some of the
minutest details of any organism, or to get over any difficult test,
and I see that my microscope, after all due preparation, and with
the best prospect of light, fails to answer my expectation, I refer,
as a last resource, to my prism, and get from it a coloured sunbeam.
Blue or green are the colours which I prefer; they are the most
suitable for the purpose.

The elimination of every, even the slightest, chromatic aberra-
tion obtained by this means increases, in my opinion, the defining and
penetrating power of the microscope, and enlarges its dominion on
the field of observation. Different other means have been now and
then suggested, such as an alcohol light saturated with chlorine of
iodine, or a light passed through a stratum of cupro-aremoniacal solu-
tion, or even through a glass of cobalt: all these lights may be very
useful and for some special purpose even preferable to any other, as

Royal Microscopical Society. Lah

Dr. Woodward observed, speaking of photography ; but for direct
observations with the microscope, the effects obtained by them are
by no means to be compared with the marvellous results of a mono-
chromatic illumination.

And I do not think it absolutely necessary for this purpose to
have recourse to a beam of the sun, which in many countries less
favoured than Italy is not rarely a mere desideratum, and very
often a dim, cloudy thing.

A brilliant luminous point of electric light—a light obtained
from oxhydrogenic flame—acting upon lime, magnesium, or zirco-
nium, perhaps also the magnesium-wire lamp, may supply the
deficiency of the sunbeam. Lach of these, simply white lights,
decomposed through a prism, will give a monochromatic illumina-
tion sufficient to reveal the best structural details, which up to
this day baffled the keenest researches of the student.

[The following note has been sent to us by Professor Joseph
Gagliardi, who received it from Count Castracane, and we print it
here because it has reference to the foregoing paper. |

“As I am now settled in my new residence (near the Capitole),
I began three days ago to work in earnest. My newly self-imposed
task is to examine the Pinnularia genus, in order to ascertain if the
ribs (coste) or pinnules of the different species be not truly con-
tinuous, but rather a series of dots close pressed together, in which
case the distinction between the two genera Navicula and Pinnularia
ought to be superseded. From this very moment I may say, without
fear of mistake, that P. oblonga is distinguished with riblets (costole)
made up of a series of small lines (lineette) parallel one to the other,
and extremely minute—I was able to value their number to 4160 to
a millimétre. Nevertheless, I cannot yet say I have recognized any
discontinuity in the pinnules of P. nobilis. As soon as I shall have
leisure to study with due attention, and with the monochromatic
illumination, the principal types of the said genus, I shall publish the
result in a special article. .. .

“Yours affectionately,

“ WRancis CASTRACANE.
“Rome, 18th February.”

178 A Few Experiments

V.—A Few Experiments bearing on Spontaneous Generation.
By Mercatre Jounson, M.R.C.8.E., Lancaster.

Srvce Professor Frankland’s careful repetition of Dr. Bastian’s
experiment on spontaneous generation still leaves the matter more
decidedly in favour of the “ab ovo” theory, which I attempted to
support in ‘M. M.J.,’ November, 1870, I am inclined to hope that
the following experiments will still seem to point in the same direc-
tion. The practical importance which the subject is takmg m
reference not only to the preservation of commercial products, as
meat, preserves, fish, wines, drugs, &c., but in its bearing upon
epidemic disease, render acceptable any communications that can in
any way throw light upon the subject. I therefore trust this may
not be devoid of interest.

One wine merchant of my acquaintance tells me that he washes
his bottles out with Condy’s fluid and water, and finds his wines
(especially claret) to keep better for it. He also tells me that when
opening a bottle of light wine, such as hock, claret, or sauterne,
which is not to be consumed on the day of opening, that he burns
a small sulphur-tipped match in the neck of the bottle, by which
means the wine is preserved from acetous fermentation for about a
week.

Aug. 12th, 1870.—I boiled a pint of distilled water in a Florence
flask, and whilst at boiling heat inserted 20 grains of tartar emetic.
This caused a new ebullition, as if some change was taking place
either in the water or the salt. The bottle being quite full, I inserted
a conical cork, and sealed it tight.

Aug. 13th.—In a wide-mouth stoppered bottle contaiming 23 oz.
of air, I put 8 oz. water and two cubic centimétres of a solution of
potassic permanganate, containing 1 grain to every 10 centimétres
of water. After shaking for a few minutes, I inverted the stoppered
neck into a cup containing water and permanganate. The bottle was
afterwards frequently shaken.

Aug. 19th.—I filled some 2-0z. clear glass bottles with the liq.
antim. tart. made Aug. 12th. I then displaced half the contents of
the bottle (1 oz.) by the air washed with permanganate, and marked
the bottle A. The second bottle, B, was served in the same way. In
C, I burned a small piece of sulphur in the air contained in the upper
half of the bottle.

D had 10 drachms displaced by air which had been washed with
carbolic acid.

In E, 1 oz. was displaced by air in which carbolic acid had been
volatilized.

In F, 1 oz. was displaced by air which had been washed with an
aqucous solution of sulphurous acid.

These bottles were all corked tightly, and sealed over, so as to
prevent access of air.

a

bearing on Spontaneous Generation. 179

I find in my notes, Sept. 25th, 1870 :—

A has a sediment of leptothrix (?) at bottom. This did not form
so soon as the others.

B, several leptothrix plants (?) formed early.

C has a plant of mucedo, eruEn, floating on the top; a dense white
sediment at bottom. This liquid was quite clear for ten days after it
was put up.

D, copious deposit of filaments.

HK, a plant of leptothrix (?) at bottom.

F, a small plant at bottom.

I subsequently examined them under the microscope, and found
in A, branching leptothrix filaments containing spores in many of
the tubules, but surrounded by innumerable spores séill. B the
same asA. O, beaded filaments (green to the naked eye) on a mags
of white leptothrix filaments.

Feb. 5th, 1871.—A and B contain leptothrix filaments and spores.
The bottles have no smell.

C is a mass of beaded filaments on a plant of leptothrix. The
bottle smells musty.

D, no smell; small filaments; few spores.

._ Evhas not been opened since Aug. 12th. It now contains a white
film at bottom, composed of small filaments, not containing spores in
tubules, but a few composed of larger beads, bifurcating to form two
larger heads.

F, like E, but smaller in quantity.

For comparison, 1 oz. of the liq. ant. tart., made Aug. 12th, was
put into a 2-oz. bottle, and corked up—half air; and on Aug. 17th
leptothrix filaments began to appear.

Oct. 6th, 1870.—Dissolved 50 grains of bichloride of mercury in
10 oz. of distilled water.

Prepared a solution of iodide of potassium, of which 10 cubic
centimétres precipitated the red iodide of mercury from 1 oz. of the
above solution.

Dissolved 5 grains of tartar emetic in 1 oz. of the liq. hyd. bi-
chlorid. Then added 10 ce. of the solution of iodide of potassium,
filled the bottle up to 14 oz. with distilled water. Corked the bottle,
leaving a small bubble of air. Tied the cork down very tight, and
covered the whole of the cork and neck of the bottle with sealing-wax.
The red precipitate soon settled down to the bottom of the bottle. On
opening it, Feb. 5th, 1871, for examination, no trace of filament or
spore could be found.

At the same time an ounce and half of water, warm from the still,
was put into a bottle with 5 grains of tartar emetic. It was corked
and sealed as before; and on Feb. 5th, 1871, when opened for exami-
nation, no trace of any filament or spore could be discovered. _

Feb. Tth, 1871.—Examined the solutions, and found in the distilled
water several globular spores, one elongated so as to form a filament,
and a small bunch of four filaments with a few spores attached. The
bottles have been placed, open, in air and light.

VOL. V. Oo

180 A Few Experiments

T examined also the bottles containing the iodide of mercury, but
found no traces of organisms.

Feb. 11th.— Examined the solutions again. There is no decided
leptothrix formed in any of them. In the distilled water I found a
few spores, all round—one composed of three attached in a line.

In the liquid containing iodide of mercury I found some oval
angulated bodies, the nature of which I could not decide. They were
soon obscured by the crystals of tartar emetic forming by evapora-
tion.

Feb. 16th.— Found a large plant of leptothrix at bottom of bottle
containing antim. tart. in distilled water.

No leptothrix or spores in the bottles with iodide of mercury.

Oct. 6th, 1870.—Put some tartar emetic into a bottle with spring
water, and a second with distilled water, half air. In both cases
leptothrix filaments were soon formed.

In a bottle of precipitated bichloride, with iodide of potassium,
some tartar emetic was dissolved, half the bottle was filled with air,
and lightly corked. In this case, on Feb. 5th, 1871, no change has
occurred.

Two drachms of citric acid were dissolved in 6 oz. of water, to
which was added about a drachm of Condy’s fluid. The colour soon
disappeared, and in course of time (10 days or so) leptothrix
appeared.

Oct. 17th.—Placed the liver of a rat (fresh, and washed in distilled
water) in a 2-oz. bottle of distilled water ; inserted a cork, and covered
the whole with cotton-wool. I then placed it in a dark cupboard. In
seven hours the water below it was red with blood globules.

Oct. 28th.— Removed the cotton-wool, and found a proligerous
pellicle, consisting entirely of small paramcecia, or monads, in an
elongated condition.

Oct. 29th. Examined the proligerous pellicle, and found a few
paramcecia, but the mass consists of millions of moving pin-point
monads.

These experiments point to certain questions of interest relating
to spontaneous evolution from inorganic matter.

The first, in which air washed with disinfectants of various kinds
was introduced to bottles containing a solution of tartar emetic. In
none of them was the growth of Mucedine prevented, though in all
it was longer in making its appearance than in unwashed air. (If
this were the fitting place I could show how this is borne out by
my experience in the sick room with regard to the use of disin-
fectants.)

A second point to be noticed is the formation of the green
mucedo in the bottle to which sulphur vapour had been introduced,
which seems to me to have an important bearing on the question
of Xenogenesis. In all the cases, I conclude the germs must have
been in the liquid, but not in the air above.

In the second experiment with bichloride of mercury, if germs

bearing on Spontaneous Generation. 181

are living they would be destroyed by this corrosive, and if pro-
duced out of the morganic CHOWN of the tartarate, they might
still arise by spontaneous evolution ; as all the corrosive sublimate
was again removed by precipitation by the iodide.

In the case of the distilled water solution, if the filaments arise
out of the inorganic CH ON, here was an opportunity for that to
take place. But we find no change, as there were no germs in the
water, none in the salt, and no air for them to arise from.

In the experiment with citric acid, the mucedo is formed in
spite of the Condy’s fluid; which at once indicates that this disin-
fectant is not fatal to all forms of protozoal life. In 1866 I found
that neither Daphnia pulex, the larve of gnats, nor minnows, were
at all inconvenienced by Condy’s fluid, while carbolic acid speedily
killed them all.

The experiment with the liver of a rat seems to show that
cotton-wool is not a safe protector against “germs” !!

As one who has looked anxiously for motion as a sign of life in
the “‘ pin-point ” monads, especially as distinct from the current and
Brownian movements of inorganic particles, | cannot but feel much
sympathy with the remarks in this Journal of Feb., 1871, pp. 81-2,
“On Motion in Microscopic Granules,’ quoted from C.8., in the
Boston Journal of Chemistry. The remarks in Professor Frank-
land’s paper in ‘ Nature,’ Jan. 19, 1871, “On the Movements of the
Dumb-bell,” particles of glass (which might have led to error in less
experienced hands than those with whom he was associated) show
how necessary it is to be cautious in minute examinations. I have
myself called attention, in a note, ‘M. M. J.,’ April, 1870, p. 200, to
the movements of sodium on water when ignited, which resemble
those of some forms of monads. I would venture to suggest that
when movements of a particle or object are referred to as a proof of
vitality, some detail of description should be given as to the modes
in which such movements occur.

As a rule there is much difference between the cyclical move-
ment of a small monad, and the slow, irregular, jerking movement
of particles, which is due to evaporation of the liquid, and the
regular, synchronous, and similar-direction-movements of particles
in a current, or those movements which are seen in examining
infusions, and produced by the action of some moving animalcule

‘ which is outside the field of view.

( 182 )

NEW BOOKS, WITH SHORT NOTICES.

Microscopic Objects Figured and Described. By John H. Martin,
Honorary Secretary to the Maidstone and Mid-Kent Natural History
Society. London: Van Voorst. 1870.—Apart altogether from our
desire that Mr. Martin had not written this work, we must express
our regret that the publisher has sent it to us for review. We say
this because we suppose he insists on a notice, and it is not in our
power to say a single syllable in praise of the volume. It is without
any aim; it can serve no purpose; and it is altogether the worst
thing of the kind that we have ever seen. There is not, in the whole
collection of plates any one which is even fairly passable, and there
are many which are as truly execrable as it is possible to conceive.
There are 194 drawings of various objects without one that we can
say is fairly executed, and indeed some of them are so abominably
handled that it is a matter of surprise to us that the author—be he
possessed of the smallest possible experience—should have allowed
them to appear. But, apart from this, the book is altogether aimless.
Every one, or nearly so, of the objects (with the exception of some of
Mr. Forbes’s specimens at the end) have been done, and exceedingly
well done, before, in various treatises on Natural History and Histology.
And even the rock specimens have been in part done, and very admi-
rably so, in an article some years ago by Mr. Forbes, in the ‘ Popular
Science Review’ We have never beheld such abominable misrepre-
sentations as the plates, for indeed there is not the faintest depth in
them ; there is a horrible flatness about them which gives one the idea
of an ordinary drawing crushed out flat, so as to effectually remove
any traces of perspective. We should gladly have avoided saying
anything about the work at all, but it would be unfair to our readers
to pass any but a most unfavourable critique upon work which has
been so execrably handled.

The Natural History of the British Diatomacee. By Arthur Scott
Donkin, M.D., Lecturer in Medical Jurisprudence to the University
of Durham. London: Van Voorst. 1870. Part I.—This is the first
part of what, when it is completed, will be an extremely useful book.
But we fear it will not be finished within the time that the author first
proposed. The plates are by Tuffen West, and of course are good ;
but somehow or other they do not appear to be the best work of that
skilful artist. It may be that, as we judge from the cheaper edition,
which alone the publisher has sent us, we may do the artist an injus-
tice, but certainly the specimens which we have seen do not convey
the idea that they are worthy of Mr. West’s hands; still, they are very
fair plates, and as they contain no less than forty-one figures, they are
good, considering the price at which each part is sold. The author's
work is, so far as we can see, well done, though he has not modified
his statements in correspondence with the modern idea of a diatom.
For example, he still describes the navicule as being striated, instead
of being composed of a series of hemispherical nodules. He considers

PROGRESS OF MICROSCOPICAL SCIENCE. 183

that he is justified in maintaining the old description, because the
microscopes employed by “naturalists” do not exhibit the peculiar
spheres of silica!! This is, it seems to us, a mistake, but of course
it is a trivial one. The synonyms appear to be fairly stated; but
we fancy that the distribution might in some cases be a little more
fully given. On the whole, we may fairly say that the work is well
done, and we may hope that the future parts will, if anything, exceed
in value the present one.

PROGRESS OF MICROSCOPICAL SCIENCE.

The Microscopic Characters of certain Rocks.—Geologists are gradu-
ally becoming more accustomed to the microscope in the practice of
their profession. It is becoming essential for every geologist to use
this instrument when possible in the examination of rocks. We have
before us a reprint from the ‘ Philosophical Magazine’ (February) of a
paper by Mr. J. Arthur Phillips, F.C.S., on the microscopic character
of certain Cornish rocks, which affords ample testimony of the value of
the instrument. The microscopical specimens on which the author
speaks have been prepared in the usual way, but the softer varieties of
killas have received exceedingly careful manipulation. In the case of
the more fissile specimens, it was often found very difficult to obtain
satisfactory sections at right angles to the cleavage-planes; and even
when procured, great care was required in mounting, to prevent their
entire disintegration in the balsam employed for that purpose. Hach
section was examined by the aid of two different arrangements of the
instrument. The first, spoken of as “a low power,” magnified 60, and
the second, mentioned as “a high power,” about 400 linear. The
polariscope could be conveniently used with both. Higher powers
were sometimes, but not often, employed. The author says that thin
sections of the “killas from Polgooth Mine,” when examined by
transmitted light under a low power, exhibit no decided evidence of
structure, but appear as a milky-white mass in which are disseminated
numerous moss-like semi-crystalline markings of a brownish-green
colour. They are also observed to be traversed by various fissures,
which have become filled by crystalline transparent quartz. When
examined by a higher power this rock is found to consist of an aggre-
gate of minute granules intimately blended together, and without
definite outlines. There were also some grains of oxide of iron and
_ other dark markings not sufficiently opaque for this substance, some
are apparently hornblende, and others are probably patches of a
chloride mineral. This slate has undergone so great a change that
the original grains of which it is composed can only be made out with
the polariscope. Speaking of killas from Polmear Mine, 40 fathoms
below the surface, the author having: first given the chemical composi-
tion, says that sections prepared from this rock do not differ materi-
ally from those obtained from the Polgooth specimens. The ultimate

184 PROGRESS OF MICROSCOPICAL SCIENCE.

fragments of which it is composed are exceedingly minute; but
granules of quartz of an appreciable size, and affording colours with
polarized light, are disseminated throughout the fine-grained matrix.
A greenish tint is also imparted to it by chlorite ; and it is minutely
divided by a system of markings made up of pairs of nearly parallel
lines, each about >,)59th of an inch in length and zj55th of an inch
apart. These cross each other so thickly as to form a kind of close
network, and give no colours by polarized light; they were at first
taken for amorphozoa; but his friend Mr. R. Etheridge, who kindly
examined them for him, is of opinion that they are “certainly not
organic.” In regard to the “ Roofing-slate, Delabole,”’ the author,
unable to arrive at a decisive opinion, sent a specimen to Mr. Sorby,
F.R.S., who says:—“ The dark crystals in the slate from Delabole are
similar to what I have seen in many others. As far as I can make out,
they are imperfect hexagonal plates; and since the general character
clearly shows that they must at all events contain much iron, it seems
very probable that they may be more or less altered specular iron.
This, of course, would well agree with the fact of its containing titanic
acid.” The author gives several other examples; but for further
information we must refer our readers to the journal in which the
paper originally appeared.

Species of Atax Parasitic on Fresh-water Mussels——M. Emil Bessels
has written a paper on the above subject in the ‘ Wirtembergische
Naturwissenschaftliche Jahrrshefte’ for 1867, which has been trans-
lated by Mr. Dallas into the ‘ Annals of Natural History’ for January.
The paper is of some little length, and will well repay perusal. His
observations have been especially made on the development of Atax
ypsilophorus, and as far as originality is concerned refer to the forma-
tion of the blastoderm. How long, for instance, after the deposition
of the eggs the blastoderm makes its appearance no one can say with
certainty, inasmuch as the deposition itself cannot be observed, In
eggs which were taken from the branchie of the Unio or Anodonta,
and apparently had undergone no change after deposition, he usually
detected the first traces of the blastoderm in from two to three days.
It is formed insularly, as may be easily proved by opening an egg
carefully in a solution of 1 per cent. of bichromate of potash. It is
impossible to ascertain the process of formation by the direct observa-
tion of the uninjured egg, on account of the dark colour of the yelk.
After the blastoderm has grown round the whole of the yelk, the em-
bryonal envelope which Claparéde describes as the deutovwm separates
from it. This is produced in exactly the same manner as the larval
membrane of the Crustacea, as observed by Van Beneden and myself
in various species of Gammarus.* Claparéde was at first inclined to
regard this envelope as the homologue of the} structure which in
insects has received the unfortunate name of the “amnion ;” but he
soon gave up this comparison. M. Bessels, on the other hand,

* J, van Beneden and E. Bessels, ‘ Résumé d’un Mémoire sur le Mode de For-
mation du Blastoderme dans quelques groups de Crustacés,” ‘ Bull. Acad. Roy.
Belg.,’ 2° sér., XXv., p. 443. ;

PROGRESS OF MICROSCOPICAL SCIENCE. 185

regarded the membrane in question in the Mites as homologous with
the larval membrane of the Crustacea, and the latter as homologous
with the “insect-amnion,” for which he has elsewhere proposed the
better name of “protoderm.” Shortly after the formation of the em-
bryonal envelope, we see, between it and the blastoderm, the first
amoeboid cells (hamamebcee of Claparéde). He remarked that these
cells “are blood corpuscles of quite abnormal derivation.” In using
this expression he had the circumstance in his mind that they are
formed from separated blastodermic cells, which, at the time of their
production, are the sole cellular structures that are found in the egg.
He did not then feel it necessary to say anything more upon this
point, as the publication of his original memoir was to be expected.
He thought at first that the blood corpuscles were all developed from
separated blastodermic cells, and only afterwards, perhaps after the
formation of the buccal orifice, passed through this into the embryo.
As, however, he never saw any such migration of the cells, even after
observing them for hours, he has given up this view, and now thinks
that there is a further formative focus for them in the interior of the
embryo. His present opinion as to the hemameebz is, that they really
agree perfectly in form and behaviour with blood corpuscles, but
nevertheless cannot be regarded as blood corpuscles. He sees in
them appurtenances of the embryonal envelope which Claparéde
denominates the deutovwm. Whilst at the commencement of embry-
onal development of many insects a cellular envelope separates from
the blastoderm, and in some crustacea a larval skin, which is usually
structureless, in Atax a larviform structure first separates from the
blastoderm, and shortly afterwards the contractile cells. This state
of things, when regarded in this manner, furnishes an additional
reason for regarding the embryonal envelope of Atax as the homo-
logue of the protoderm of insects.

Observations of Pachytragous Sponges.—Some observations of an
interesting character have recently been made by Mr. H. J. Carter,
F.RS., on certain sponges from the south coast of Devon. The chief
point of interest in these sponges—Dercitus niger, Stelletta aspera, and
S. lactea—is the presence of peculiar cells in Dercitus niger and Stel-
letta aspera, corresponding in multiplicity, position, and general dis-
tribution, though not in composition, to the globular crystalloids or
little silicious balls in the crust and body of the Geodide ; add to
this their contents, which render them so much like reproductive
agents, and, lastly, their occurrence in the two sponges mentioned,
and not at all in the third, viz. Stelletta lactea. Nor do they exist in
Pachymatisma Johnstonia ; but in the dried specimens of Geodia gigas,
presented to the British Museum by Dr. Oscar Schmidt, there are
similar cells in abundance, together with the globular crystalloids.
Although analogous in multiplicity, position, and distribution to the
globular crystalloids in the Geodide, they not only differ from them,
as just stated, in composition, by the former being cellular and albu-
minous, while the latter are solid and silicious throughout,* but also in

* «Annals of Natural History,’ 1869, vol. iv., p. 16, &c., pls. 1 and 2, figs, 12
and 14.

186 PROGRESS OF MICROSCOPICAL SCIENCE.

size; for the largest crystalloids are three or four times as large as the
largest cells, and the latter much larger than the smallest or youngest
crystalloids, so that in these respects, viz. in composition and size, they
cannot be confounded. Formerly Mr. Carter thought that the colour
of the sponges might be always sought for in the ampullaceous sacs
(“ Wimperkérbe,” Schdt.), and therefore that the black cells of Dercitus
niger might be ampullaceous sacs ;* but the result of more particular
examination subsequently, as given above, has caused him now to
regard the latter more as reproductive agents. He has also alluded
to the presence of ampullaceous sacs in Geodia gigas, Schdt.; but on
examining these also again, now that he has become more intimately
acquainted with the composition of the cells in Dercitus niger, &e., he is
led to conjecture that they also may be of the same kind as the latter,
in which case, should he be right, we shall have an instance in this
sponge where both the globular crystalloids and the cells occur to-
gether, and thence have to seek for the ampullaceous sac under some
other form than that in Halichondria simulans, not only in Geodia
gigas, but in Pachymatisma Johnstonia and in Stelletta lactea, &e.,
where there is nothing of the kind like the ampullaceous sac of the
Halichondria mentioned, so far as the larger size of its cellules and
peculiar grouping go. The ampullaceous sac with smaller and thus
less-marked cellules may exist in all; but as yet he has not been able
to substantiate this. Of course, after having been dried, it is impos-
sible to make out anything in these cells so satisfactorily as in living
ones; and hence, although such cells are present in great abundance
in their contracted state in the dried specimens of Geodia gigas men-
tioned (measuring about 1000th of an inch in diameter and filled with
a number of cellules), liquor potasse, although it causes the cellules
to run together into one homogeneous mass, does not yield any satis-
factory demonstration of a nucleus under the addition of nitric acid,
nor is the cell-wall well marked—two points in which the cell of
Dercitus niger differs distinctly from the ampullaceous sac.

Cancer of the Kidneys in Children —Dr. P. M. Braidwood, who has
contributed an excellent article on this point to the ‘ Liverpool Medi-
cal and Surgical Reports’ (vol. iv.), gives the following as his experience
of the structural degeneration seen in the gland :—The firm yellowish,
and the whitish less consistent portions of a cancerous kidney are
found to be composed of delicate fibres enclosing in their meshes
fusiform, round, oval, or irregular cells. The fibres are observed to
be extremely delicate, distributed sparsely, and enclosing cancer-cells,
which are small, oval, or round. Among the fluid contents of the
cysts are seen large, oval, round, or irregularly-shaped, multinuclear
cancer-cells. Generally at one part in the circumference of such a
cancerous mass is to be seen a reddish edge of seemingly normal
tissue, which on microscopical examination is discovered to consist of
tubuli uriniferi and their malpighian terminations undergoing can-
cerous degeneration. The urinary tubules at such a point appear to
be lined by very minute, round cancer-cells, which, on being detached,

* ¢ Annals,’ 1870, vol. vi., p. 332.

CORRESPONDENCE. 187

or when submitted to the action of dilute acetic acid, exhibit their
multinuclear character and granular contents. At certain turns in
the tubules the cancer-cells are accumulated in heaps, while in the
malpighian corpuscles they are large, subdivided, and contain numer-
ous nuclei. It seems probable, then, that the connective tissue cells
of the cortical and inter-pyramidal portions, and likewise the epithelial
cells of the proper renal tissue, are transformed into or replaced by
cancer-cells.

A New Genus of Graptolites—Mr. J. Hopkinson, F.R.M.S., F.GS.,
who gives a very interesting paper on Dicellograpsus in the ‘ Geolo-
gical Magazine’ (vol. viii., No. 1), has used the microscope in his
investigations. The author’s remarks, which extend to the descrip-
tion of five new species, are too long for abstract; but the paper is
full of interesting facts, which show how valuable the microscope is in
geology.

CORRESPONDENCE.

Tue Errors or Lenses—Mr. Wenuam anp Dr. Picort.
Yo the Editor of the ‘ Monthly Microscopical Journal.

BALLINAMALLARD REcTORY,
Co. Frrmanacu, Feb. 15, 1871.

Sir,—A. well-known philosopher of former times, Scaliger, used to
teach that for getting at the truth in a difficulty there was nothing
like controversy ; “for as ight,” he says, “ from the collision of flints,
so truth is struck out from the collision of minds.” Whether this be
so or not in general, in the present controversy in your pages it seems
in some danger of failing; for in the last paper of Dr. Pigott the
point at issue had been so obscured by things not relevant, that,
except to very watchful readers, it may seem doubtful whether any-
thing at all has really resulted from the discussion. As, however, the
question has in fact been reduced to a very narrow and a very definite
issue, it would be a thing to be regretted if this result should be lost
sight of. I would, therefore, with your permission, point out how it
now stands.

Immersion lenses being admitted to be superior to the others, Dr.
Pigott claims to have discovered the cause of this superiority, the
object supposed mounted in a medium like balsam. His theory is
that they have a greater aperture. For with the other object-glasses
the more oblique rays are lost by total reflexion at the cover; but
with the water-lens a much wider pencil is transmitted to the eye.
And in token of this he constructs the elaborate diagram, Plate LX.,
to show how much exactly is the difference in the angle. By this he
claims to have cleared up “the mystery of the water-lens.”

To the first assertion—viz. that with the common lens the angle
cannot exceed 82°-—Mr. Wenham replies, this is true; but it is not

188 CORRESPONDENCE.

new, haying been pointed out long ago by others, himself among the
number.

To the second part—that the more oblique rays can enter with
the water—he replies, true they can enter the front lens; but to what
purpose? From this lens they emerge too oblique to enter the back
combinations, and therefore they do not reach the eye. If the reader
will turn back to the upper of the two figures in Plate LX., this will
be very plain. Take one of the more oblique rays, e.g. that num-
bered 6 or 7, and produce it straight on (there is no change here by
refraction), then it is at once seen that such a ray will pass outside
the back combinations and be lost.

This is, as we might say, checkmate,—in one moye. Dr. Pigott
committed the oversight of forgetting that the back lenses must be
taken account of. Having seen his rays safely into the front glass,
he takes no thought for the rest of their journey, assuming that if
they can enter the front they will also enter the eye.

In strictness, no more is required so far as Dr. Pigott’s discovery
is concerned. His theory is shown to fail in its proof, and this quite
independently of anything that may be put in its place. Mr. Wenham,
however, goes farther than this. He supplies a correct figure, with
the rays projected through a real object-glass, to take the place of
Dr. Pigott’s imaginary one; and he points out how to determine pre-
cisely the limit of the aperture which the immersion lens does admit
of. The reasoning by which he fixes this, which is somewhat close
and concentrated in form, is given in the second paragraph of p. 17,
and may require some slight attention from the reader to follow it.
It may be paraphrased as follows :—Taking a dry object-glass, the
pencil issuing from the object cannot exceed 180°. This being re-
fracted by the flat surface, is converged to a pencil, which cannot
exceed 82°. This is again refracted at the second surface of the front
to a narrower pencil, whose angle determines the figure of the back
lenses and the pencil they admit. Remove now the dry front, and
substitute the immersion, other things the same. To find the extreme
ray of our new objective, we must begin to trace its course in the place
where it is known; that is, we trace it inversely from the back com-
binations, for which we have already fixed the maximum limit. This
we have found to be such that, tracing inversely to the inside of the
front, the rays will there be found converging at an angle not exceed-
ing 82°, These we trace thence into the balsam (without change) till
they converge at the focus, thus determining a maximum aperture of
82°, the same precisely as for the dry lens.

Unfortunately, Dr. Pigott has omitted to read this, or else has
failed to understand it. That something is wrong in his diagram he
has indeed become conscious after seeing Mr. Wenham’s figures; and
in a foot-note to p. 70 he admits that his own diagram will not work,
but curiously he regards this as of no consequence. He accounts for the
mistake, and expects it should be allowed to pass on the very remark-
able plea that when he made it he was thinking only of the front.
Precisely so; his mistake was that he thought only of the front when
he ought to have thought of the rest as well. The aperture of an

CORRESPONDENCE. 189

object-glass is measured not by what reaches the front but by what
reaches the eye.

Having in this way disposed of his own mistake, he points out one
of Mr. Wenham’s, which he fancies he has discovered—a mistake which
seems to him so odd that it affords him a good deal of amusement, and
is in his opinion a legitimate subject for “chaff.” In determining the
immersion aperture, it seems that Mr. Wenham immerses the front of
the glass not in water but in balsam; thus, as his critic pleasantly
says, “demonstrating the principle of the water-lens by applying it
without the water to prove its action with it (save the mark!).’ Here
Dr. Pigott is amused only because he does not understand. In the
water-lens there is glass, water, then glass again, the last in contact
with balsam. Mr. Wenham, when tracing backwards the course of
the ray, to avoid complications not essential, treats the water as if it
were a continuation of the glass, properly neglecting the effect of the
water on the obliquity because it has no effect, since the ray after
leaving the water film recovers its former direction.

The other parts of Dr. Pigott’s paper do not touch the question.
The aquariums, the gold fish, Claudius Ptolemy, the bent oar, and the
laws of refraction, are nothing to the purpose, though brought in as if
they were decisive. It is for this reason I have said that the question
was obscured by the introduction of things irrelevant. The history of
Claudius Ptolemy is no more to the point than the history of Claudius
Cesar or Claudius Lysias. No more are the laws of refraction and
reflexion, repeated (for about the twentieth time,) because these laws
are “first truths” and are known to everyone, and never are nor ever
have been denied by anyone great or small. There is, no doubt, a
sense in which this or any other optical question may be said to depend
upon them; the same sense in which we may say that a question about
the nutation of the earth’s axis or the motion of the moon’s apse
depends upon the multiplication table.

These laws are brought in on every occasion with much arithmetic,
and mathematics done with Greek. This display of learning seems
to have impressed his readers so much that even skilful observers fear
to trust their own faculties against mathematics so original and pro-
found. In a former letter I pointed out that those who looked into it
might find there was some slight misapprehension about this. No
doubt it is very hard for non-mathematical microscopists to think.so,—
to believe that so much mysterious mathematics can have nothing in
it, especially after their nerves have been shaken by meeting such
words as Pneumo-spherical and Hydro-spherical, Aberrameters, Krato-
meters, Refractometers, Hidola, and all the rest. But so it is. The
whole of this “original” learning from beginning to end, the picture
of the bent oar not excepted, is simply copied out of the first pages of
the little books for beginners, the primers and horn-books of optics.
Examples are given in the primers to be worked out, and Dr. Pigott
works out other examples with the numbers changed,—that is all.
The “original” part is that he works them with infinitely more
trouble than is needed ;* which explains his statement that they have

* As an example typical of this superfluous work, we may take the ease of the
mercury globule in pp. 265, 266 (vol. iv.). Beginning, as he does, with the primary

190 CORRESPONDENCE.

cost him, as evidently they have, “ immense labour.” What is not so
easy to explain is his not having discovered that what costs him so
much trouble, costs others neither trouble nor time. , And when they
are put forth month after month as “original researches,” we can do
nothing but look on in silent wonder.

. Your obedient servant,
S. Lustre Braxry.*

A Proposat as to Diaroms.
To the Editor of the ‘Monthly Microscopical Journal.’

Dear Sir,—I think the thanks of all amateur microscopists who
are interested in making classified collections of diatoms are decidedly
due to Captain Lang, the President of the Reading Microscopical
Society, for his generosity in making public his method of selecting
and mounting diatoms, and for the very interesting paper on the
subject which appeared in the December number of your excellent
Journal, It is as a rider to his paper that I venture to trouble you
with these few lines, in the hope you will publish them, as I am of
opinion that if by a discussion of the subject some mode could be
discovered or agreed on by which amateurs might be able to purchase
prepared or unprepared diatomaceous material, or to interchange
small quantities—say even a single dip evaporated on a glass slide—
of gatherings containing dissimilar forms, great benefit would accrue
therefrom. I have had the pleasure of conversing and corresponding
with Captain Lang on these points, and I know that his ideas and
mine on the matter are very similar; therefore I have the less hesita-
tion in asking you to ventilate the subject.

At present, among amateurs, there exists much difficulty in
getting material which shall contain a great variety of species and

equation, writing it in numbers instead of symbols we get at sight, without caleu-
lation, the value of q, and the required diameter is, at sight, one-fifth of it. This
is the whole work. Not a cipher nor a letter has to be added. The reader can
now turn to p. 266, and, if he likes, improve himself in algebraic fractions, the
Binomial Theorem, and Infinite Series, by working through Dr. Pigott’s “ caleu-
lation.” As for the equation itself, this and the method to be followed, and the
figure, everything except the wonderful workmanship, are copied out of the
manuals,—a circumstance which Dr, Pigott did not think it necessary to
mention.

* P.S.—Since this was written some prominence has been given in the last

Number to the instrument introduced, or revised, under the name of the _

“ Aplanatic Searcher.” I ought, therefore, perhaps to add that none cf the above
remarks have any reference to it: as its principle or construction has not formed
the subject of any one of the papers contributed by Dr. Pigott to this Journal.
Time and the sure test of experiment will determine its practical value ; mean-
time those outside a certain circle, knowing nothing, have of course nothing to
say. My criticisms apply only to the Mathematical Optics in this series of
papers, about the merit of which there has grown up, as it seems to me, so very
remarkable a misconception; remarkable as showing the incredibly low level at
which the scientific knowledge of optics exists among English observers, when
many of them—so skilful and accurate in observation as every part of this Journal
proves them to be—can yet believe these papers to be an accession to the stock of
our knowledge.—Warch 8th.

an

Te” ”™ClO eee

CORRESPONDENCE. 191

genera, You may make gathering after gathering in your own neigh-
bourhood, but though you may make a large collection of material,
which you could not use up in your lifetime, your gatherings would
very likely contain but multitudinous repetitions of the same class of
diatoms. It would probably be the same with the gatherings you
might make in your sea-side trips, and still more probably so in your
preparations of guanos from different localities. The consequence is
that you would in all likelihood get tired of making gatherings, and
having the trouble of preparing and cleaning them.

Diatomaceous material, either prepared or unprepared, cannot, as
far as I am aware, be bought unmounted, whether it be of British or
foreign genera; and the present mode of exchanges amongst amateurs,
carried out through the exchange columns of different journals, is
unsatisfactory in the extreme, as one can never know what kind of
rubbish he may have sent him in the way of barter.

The professional preparers will not sell material in even the
smallest quantities. It seems almost incredible, but let the following
statement, which I vouch for as fact, speak for itself, and you will
see, that though to prepare a mixed slide for the market the preparer
has to put a certain sized dip of material on a glass slide and evapo-
rate it, if you ask him to stop the process there, and sell you that
slide for a shilling—the same price, mind you, that he will ask for it
when it is completely mounted and ready for the market—he will not
sell it you. No! He will cover it with Canada balsam and a glass,
he will clean off the superfluous material, and perhaps take the trouble
of putting on a ring of cement, and when he has thus spoilt it for the
purposes for which you want it, he will offer it you for a shilling.
This is precisely what happened to me. I offered to a well-known
preparer of microscopic objects, whose name I will not mention, a
shilling a-piece for a single dip—the ordinary quantity put on a slide
—each of certain deposits from which I wanted to select forms myself
for my own cabinet, and he refused to let me have them. I thought I
should succeed in my object: by ordering some of these preparations
mounted dry, and by melting the cement and removing the cover I
could get what I wanted. But do you think I was allowed to have
them? No! Itis usual to mount them in balsam, and in balsam I
must take them, or go without. There is a certain class of diatoms
only, that the mounters put up dry for the market, and from these only
are you allowed to select. Foiled in my first attempt, I made appli-
cation to another equally well-known mounter, and I should like to
publish his name, because he did at any rate write me a very civil
letter in reply, showing me that it was not his fault that he could not
comply with my request, but as I have not his authority to do so, and
he might not like it, I refrain from doing so; but I give the text of
his letter, as I think it may be interesting. He says:—

“ Str,—I beg to assure you that I have not forgotten or neglected
to notice your letter of the 14th instant, but have given to it frequent
thought. I regret that I cannot comply with your wish, from various
causes. Many of those diatoms are not my own mounting, and those
who have the material would not listen to your wishes, I am sure,

192 CORRESPONDENCE.

however reasonable they may seem. If I were to try, it would take
me immense labour to write a long letter to each of twenty persons,
perhaps, which ten out of twenty would not understand, and would
not reply to; and the few who might comply would be almost sure to
send something not pleasing to you. If you go one inch out of the
daily beaten track every obstacle is thrown in the way, and everything
that is possible is done wrong. If I could get you twenty dips the
time alone would be worth 20s. “ With thanks, I am, &e.”

Now, I should think something might be done to make these
vendors more reasonable, who thus attempt to force amateurs who
want to make a systematic collection of selected slides, to purchase
only their selections, at from eighteenpence upwards; or if they
cannot be brought to reason, we have the remedy in our own hands if
we choose to apply it. In London, or in such a town as Liverpool,
where ships are daily coming in from all parts of the world, I am sure
it would pay an optician, as a business speculation, to order a quantity
of diatomaceous deposits and foraminiferous sands, &c., &c. The
localities where they are to be obtained are perfectly well known; the
price of the raw material in those places is little more than the cost
of labour in collecting them. The freight of a few hundredweights
would be trifling, and they could be sold, either prepared or unpre-
pared, at two or three hundred per cent. profit, and if properly adver-
tised, and if notification of the fact of their being on sale were sent to
all the Secretaries of Microscopical Societies in England, I venture
to say the deposits would not remain long on hand.

It may be said that it is difficult, if not impossible, to find out
what towns possess Microscopical Societies. I think this difficulty
might be met by proposing that any provincial association might be
affiliated to the Royal Microscopical Society by paying a yearly fee
of, say, half-a-crown to have its title and the names of its President
and Secretary registered ; and if lists of such societies were periodi-
cally issued, sufficient publicity would be obtained.

With regard to British species, nothing could be easier than to
facilitate their dissemination by the following plan. It is astonishing
what a very small quantity from any gathering is amply sufficient for
a man’s own use. Suppose that every member of a Microscopical
Society who made a gathering or preparation, whether marine or
fresh-water, after carefully examining it, and noting the particular
diatoms it contained, should present what he did not require for his
own use to the society to which he belonged, of all of which prepara-
tions the Secretary should make a list. Now, although the individual
might not like to sell his preparation, I can see no reason why the
society might not sell it, at so much a dip, according to its plentifulness
or scarcity, and the trouble and expense of cleaning it; but I should
think from 2d. to 6d. a dip would be ample, anda common medium for
advertising these could easily be found. Such a mode of proceeding
would, of course, not interfere with gentlemen exchanging their
mounted slides as they do at present.

Can you or any of your readers suggest a better mode of obtaining
material, by which so many more of us might be able to profit by

CORRESPONDENCE. 193

Captain Lang’s happy discovery? If not, can you assist in carrying
this out ?

.It is strange that microscopists should not generally show a
greater readiness to assist each other than we usually find. I met
with a singular case of want of courtesy a short time ago. The Presi-
dent of a Microscopical Society having informed me that fine speci-
mens of foreign diatoms were to be found among the Californian shell-
washings, which shells were bought by the dealers in Liverpool, who
sold the washings, but that he could not give me the address of a
dealer, I wrote to the Secretary of the ‘Liverpool Microscopical
Society, asking for the information, and enclosing a stamped envelope
for reply. My letter never came back to me, so I presume it was
delivered; but I have never been favoured with a reply. If any of
your readers could furnish the information, in a letter addressed to
Captain Knight, Claremont Villa, Leamington, I would gladly pay
the postage.

Yours faithfully,

R. D. Kyieur.

A FRAUDULENT CoLLECTION OF SUBSCRIPTIONS.
To the Editor of the ‘ Monthly Microscopical Journal.’

Roya Microscorican Soctery, Kiye’s Conuece, Varch 20.

Dear Sir,—It has just come to my knowledge that some one has
been sending out the collecting cards of our late collector, Charles
Low, and is endeavouring to obtain subscriptions by this means.

Will you allow me to caution and inform our Fellows that no one
is authorized to collect subscriptions for this Society besides the Trea-
surer and myself, and that receipts are not valid unless signed by either
of us.

I am, Sir, yours truly,

Wattrer W. Reeves,
Assistant-Secretary.

Errata: Toe Fiaures or CrystaLs witH Smica.
To the Editor of the ‘ Monthly Microscopical Journal,
AsHDown CorracEr, Forest Row, Sussex,
March 6, 1871.

Str,—An unlucky accident delayed my receiving and returning
proofs ‘of Plates LX XVII. and LXXVIII. in March number of the
Journal, and led to the omission of correct numbers referring to the
paper.

If your readers will begin with Plate LX XVIII, and number the
figures in horizontal lines from 1 to 6, and in Plate LX XVII. from 7
to 13, they will find descriptions and figures coincide.

I am, &c.,
Henry J. Sack.

( 194 )

PROCEEDINGS OF SOCIETIES.*

Royat MicroscoricaL Socrery.
Kine’s Coiuece, March 1, 1871.

James Glaisher, Esq., F.R.S., took the chair.

The minutes of the last meeting were read and doiifteea

The Secretary announced that in. consequence of certain losses
which the Society had had the misfortune to sustain through the
illness of the Collector, and of the fact that there was a considerable
amount of subscriptions in arrear, the Council had felt themselves
compelled to advise that the usual soirée and evening party should not
be held this year. Many Fellows of the Society had expressed the
wish that in addition to their ordinary meetings there should be a
social gathering of a scientific character, where opportunities for
examining objects and discussing points of interest would be afforded.
The Council therefore would advise that the Fellows should consent to
forego the expensive evening party for the current year, and that some
convenient evening in the month of April (say the latter part—about
the 26th) should be fixed upon for holding, not a soirée, but a scientific
meeting, limited to the Fellows and a few scientific visitors. The
Council wished to take the opinion of the meeting on the question of
providing refreshment during this meeting. If the Fellows should
decide not to incur that expense (say 7/.), the amount thus saved could
be devoted to the purpose of defraying the expense of another scientific
meeting later in the year.

The Chairman in putting the proposition with regard to refresh-
ment to the meeting, said that the proposal which had been made was
to be considered not in the light of a precedent, but merely as relating
to arrangements for the present year. The vote of the Fellows was
then taken on the question of refreshment, and it was decided by a
large majority that none should be provided.

Mr. Wm. Kitchen Parker, F.R.S., F.Z.S., the newly-elected Pre-
sident, who had been detained by a professional engagement, appeared
at the table at this period of the proceedings, and was installed into
the Presidential Chair amidst the cheers of the meeting.

A list of donations was then read, and the thanks of the meeting
given to the respective donors.

Mr. Jabez Hogg (Secretary) stated that in addition to the list already
read he had received a small series of photographs from Mr. Hennah,
of Brighton, showing some illusory appearances which have oceupied
the attention of the Fellows lately in regard to the beadings on the
Podura scale. By a simple arrangement of small cylinders of glass
placed at right angles to each other and illuminated in different
directions, as they revolved curious and illusory appearances might

* Secretaries of Societies will greatly oblige us by writing their reports legibly
—especially by printing the technical terms thus: H y dra—and by “ underlining ”
words, such as specific names, which must be printed in italics. They will thus
secure accuracy and enhance the value of their proceedings.—Ep. M. M. J.

PROCEEDINGS OF SOCIETIES. 195

be obtained. The illusion is due to the glass cylinders virtually
becoming lenses when crossed, and is still further enhanced by the
focus of objects behind being within or upon the surface of the rods.
Mr. Hennah would not be understood to maintain that because in
these photographs he had obtained pseudo-beads no beaded structures
existed. He believed in some cases they might exist, although in
the majority he was of opinion that they were phantoms of refraction
and reflexion arising from special illumination of transparent structures
by transmitted light. The photographs must fulfil a mission of cau-
tion, and he (Mr. Hennah) hoped would lead to more careful exami-
nation of debatable things.

The effects photographed were obtained in the following manner:

1. Sheet of ground glass close to rods; illuminated a little
obliquely.

2. Sheet of ground glass 16 inches square about 1 foot behind
rods; slightly oblique illumination.

3. Same as 2, but with a 6-inch paper cross on ground glass, about
6 inches from rods.

4, Common “ knobbed” water-bottle close to rods.

5. Rods obliquely ; a window with curtains.

6. Rods more oblique than 5; an open window quite in focus.

7. Rods same as last; same arrangement, but out of focus.

8. A photograph behind two rods; placed at right angles, showing
distortion.

It was announced that as there were more papers in the hands of
the Secretaries than could be read during the evening, the following
would be taken as read.

A communication from the Rey. Professor Gagliardi, “ On Views of
Surirella gemma,” and another by Mr. Cubitt, “On the Winter Habits
of Rotatoria,’ would be taken as read.

In alluding to a paper contributed by Lieut.-Col. Dr. Woodward,
of the U.S. Army, the Secretary called attention to a series of beautiful
photographs of the Podura and other test-objects which Dr. Woodward
had presented to the Society.

Mr. J. Bell then read a paper “On the Microscopic Examination
of Water for Domestic Use.”

Dr. Lawson inquired under what powers Mr. Bell had made his
examination.

Mr. Bell said he had used a }th object-glass and B eye-piece, and
a s'.th and B eye-piece.

Mr. Slack attached great value to Mr. Bell’s researches. He
thought that it would require a very large body of experiments before
it would be safe to infer the composition of a solution from the pre-
sence of particular forms of fungi. In comparing some specimens of
fungi given to him by Mr. Greenish in solutions of arsenic and strych-
nia, with some in silica which he (Mr. Slack) had in dialysed solutions
in distilled water, he thought that though the appearances differed to
some extent, the plants were of the same kind. As regarded filtering
through sand, part of the action was chemical and part mechanical.
Passing water through a mass of sand was a very good mode of oxidiz- ©

VOL Ve 12

196 PROCEEDINGS OF SOCIETIES.

ing, as well as of filtering. How far chemical action operated in the
case of Mr. Bell’s experiments it would be impossible to say without
further investigation. With regard to the different sorts of fermen-
tations, he thought it would be found that more than one fungus con-
tributed to vinous fermentation, and when vinous passed to acetous
fermentation it. would be found due to the action of other sets of
fungi, and the same with butyric fermentation. If a piece of vinegar-
plant be taken and separated into successive sheets, and dried in the
oven, it would be reduced very much to the appearance of prepared
gelatine, and will even “chink” when thrown down on a plate. This
dried vinegar-plant would often excite butyric fermentation, and he
noticed a slight odour of butyric acid in one of Mr. Bell’s bottles.

Dr. Millar thought that Mr. Bell had established one remarkable
fact, namely, that old filters were better than new ones.

The thanks of the meeting were presented to Mr. Bell.

Mr. Slack then read a communication from Lieut.-Col. Dr. Wood-
ward “On the Structure of the Podura Scale, and certain other Test-
objects, and of their Representation by Photo-micrography.”

Dr. Pigott said he should be very glad if this vexed question of
the Podura markings could be agreed upon in some way; it had been
such a valuable scale in the construction of object-glasses that it could
not be prized too much. He would say, in reference to Dr. Woodward's
remarks, that before anyone depended upon the photograph of an
object as indicating real structure, they should be intimately acquainted
with its various aspects under the microscope, and decide which could
be relied upon. In photographing any object, the operator should
remember that the photographic lines show the actinic rays which
appear at the moment, and if the photographs were to give unbiassed
evidence they ought to be made under every possible condition of
focussing and correction. Dr. Woodward does not appear to have
borne this sufficiently in mind. He was, nevertheless, extremely
obliged to him for his paper, for, having placed himself at the head of
photographic science in reference to the microscope, it was satisfactory
to know that he had brought his great practical power to bear on the
solution of this subject.

The thanks of the meeting were given to Dr. Woodward.

The President then said: The honour which the Society had
conferred upon him by their election of him to the chair was quite
unexpected. He was not a professed microscopist, but a microscopic
observer, and one who felt very thankful to the ingenious and talented
men who from time to time had made improvements in the instrument.
He thanked the Fellows for his election, and should take great plea-
sure in rendering the Society any service that lay in his power. His
first visit to a scientific society was made to the Microscopical,
eighteen years ago, and for years he had attended its meetings until
allured therefrom chiefly by his devotion to the study of a gigantic
form of boatbill (Balaniceps) which had been brought over to this
country. He had also worked largely at the Foraminifera. He had
intended that evening, if time had permitted, to read a short paper
illustrating the use of the microscope in developing the embryology of

PROCEEDINGS OF SOCIETIES. 197

the skull. His work had not direct reference to the subject of
teleology, nor to the structure of the tissues; but his object had been
to work out the metamorphosis of the skull, and to see the tissues as
they begin to differentiate and modify to form the embryo. The subject
was a very large one, and had been principally laboured at by the
great German embryologists. He had spent the last two years in
studying the development of the frog’s skull, in watching the different
and numerous stages which that creature undergoes, and the relations
it bears to other creatures of the vertebrate type, always remembering
that the frog was essentially a fish. He had been in some degree un-
prepared for the extent of the metamorphic changes that the frog
underwent. He had worked out this subject into ten artificial stages,
the first of which he had obtained when the frog was in the egg. In
the first stage of its morphological development the animal was two
stages below the youngest described embryo of the lowest kind of fish,
but one. The larva of the lamprey was the earliest condition of a
fish’s skull with which we are acquainted. He had succeeded in
getting two stages below the larva of the lamprey. From this stage
he had worked up the development of the frog until he came to the
tadpole, which is the representation of the types of rays and sharks,
As he ascended in the various stages the likeness to the other verte-
brata became very apparent. In an adult frog (Rana temporaria) he
had obtained a metamorphic development of such height that it
bordered upon our own class, the Mammalia. At the same time it
should be stated that other parts of that frog’s skull retained the
simplicity of the adult lamprey. In the frog we had a ereature who
had run across the whole circle of types, creeping gradually up to the
Mammalia, and yet never losing his relation to the original type, but
retaining its structure and relation to the very end, although sub-
dividing and metamorphosing certain of the facial arches into the
very number of parts that we have in our own inner ear. The
chain of bones in the human ear (the hammer, the anvil, the round
bone, and the stirrup) had caused a great deal of trouble to anato-
mists in their attempts to trace the series of metamorphic changes.
He had, however, made this clear by tracing the history of the
facial bones of a frog, a creature which was but a fish in respect
of its earliest embryonic conditions. Supposing the doctrine of
development to be true, it would seem that we ourselves have come
originally in some line sub-parallel to the frog (he would not say
from the frog itself, although man had repeated the form tail-less).
Even in the highest oviparous vertebrates no subdivision of a facial
bar to form that tiny but really important part of the human skull,

the os orbiculare, ever obtained. In this respect the frog comes nearer
' to the Mammalia than any bird. Birds have branched out in a direc-
tion quite away from the ordinary line, and have culminated in their
own glorious types. If it is desired to trace the development of the
Mammalia, inquiries must commence with the Batrachia; and in such
inquiries the thought constantly occurs that between us and the
Batrachia there have been lost whole groups of creatures. We were
only just beginning to see the manner in which the work of tracing

198 PROCEEDINGS OF SOCIETIES,

the development of the higher forms of animal life was to be earried
on. He hoped at the next meeting to bring a paper on this subject.

Mr. Ahrens exhibited a new binocular microscope of ingenious
construction, which could be worked with the highest powers.

Dr. Pigott gave a brief description of an instrument for in-
creasing (?) angular refraction.

Mr. Richards exhibited a cheap form of pocket microscope.

The President will read a paper “On the Mode of working out
the Morphology of the Skull” at the next meeting, April the 6th, to
which day the meeting was adjourned.

Orricers AND Councit oF THE RoyaL Microscopicat Soctrery,
Exectep 8TH Frsruary, 1871.

President.—* William Kitchen Parker, F.R.S.

Vice-Presidents—Charles Brooke, M.A., F.R.S.; *John Edward
Gray, Ph.D., F.R.S., F.L.S., &c. ; *John Millar, L.R.C.P.Ed., F.L.S. ;
Francis Herbert Wenham, C.E.

Treasurer.—Richard Mestayer, F.L.S.

Secretaries.—Henry J. Slack, F.G.8S.; Jabez Hogg, F.L.S.

Council.—Robert Braithwaite, M.D., F.L.S.; *John Berney, Esq. ;
*James Glaisher, F.R.S.; *William John Gray, M.D.; Henry Lawson,
M.D.; Henry Lee, F.L.S., F.G.8.; James Murie, M.D., F.L.S. ;
*G. W. Royston-Pigott, M.A., M.D. Cantab., &c.; John Ware
Stephenson, F.R.A.S.; Charles Stewart, M.R.C.S., F.L.S.; Charles
Tyler, F.L.S., F.G.S.; *Thomas Charters White, M.R.C.S.

Donations to the Library from February 8 to March 1, 1871 :—

From

Jand:and Water. Weekly... ©... .» \s« ‘cs ieeeeeeee
Society of Arts Journal. Macs Ga So, (ate, (Lye) | ators ene Rao
Nature. Weekly .. .. oe ise’ yee, host | aR meat
Atheneum. Weekly : so, oer Wee eee
Quarterly Journal of the Geological Society, No: 105.580 .. Society.
Journal of the Quekett Club .. . Club.
On the Claims of Science to Public Recognition and d Support

By Dr. Guy, F.R.S. .. yee Author.
Journal of the Linnean Society, No50 ... «.' =e Society.
A set of photographs. By Mr. Hennah PR eo. ilies ARPT.
A set of photographs. By Dr. Woodward .. .. Dr. Woodward.

John Ligertwood, M.A., M.D., was lected a “Fellox of the
Society.

WALTER Ww. REEVES,
Assist,-Secretary.

BriGHToN AND Sussex Natrurat History Soocrery.

January 26th, 1871.—Microscopical Meeting. Mr. 'T. H. Hennah,
Vice-President, in the chair.

Mr. R. Glaisyer announced the receipt of three slides from Mr.
Wonfor for the cabinet.

Mr. Sewell, who had proposed the subject for the evening,—the
use of the Polariscope in the determination of Structure,—remarked

* Those with the asterisk placed before their names are newly elected.

PROCEEDINGS OF SOCIETIES. 199

that with most microscopists the polariscope was merely a toy to
show pretty objects, whereas he believed it ought to be applied more

. than it was to the making out of structure. Having inquired of Mr.

Curties respecting Hislop’s selenite stage, he was informed that Mr.
Ackland had contrived a very simple one, which he thought he could
borrow ; but he had done better, for he had induced Mr. Ackland to
come down to exhibit and explain his selenite stage.

Mr. Wonfor considered a large number of microscopists used the
polariscope as a scientific instrument in making out structures.

Mr. Ackland was sure the majority used it as a toy, he might say
fifteen out of twenty. Scarcely any had a selenite plate with the axis
marked. He did not think once in twenty years had he been asked to
mark the axis.

Mr. Wonfor thought that a ie amount of work was done by
microscopists without using the selenite at all, and then only with
objects possessing slight depolarizing power. They would all feel
obliged by Mr. Ackland’s pointing out the advantages of marking the
axis.

Mr. Ackland said, if the axis of the selenite film was marked,
it was possible to determine the tension of any object, especially, say,
in the examination of muscular fibre, did it point out the direction of
the tension. The Germans, who were greatly in advance of us in
minute anatomy, always used marked selenites. One of the only
persons he knew using one in London, was Mr. Stewart, of St.
Bartholomew’s Hospital. Selenite films, giving the various tints, blue,
green, yellow, red and purple, were commonly used; but all must
have noticed, when examining an object which did not fill the field of
view, that the colour of the background did not harmonize with the
colours of the object. It occurred to him that a neutral tint, cor-
responding to the tint occurring in Newton’s rings, midway between
the violet of the second wave and the indigo of the third wave, was
the one required. In a parcel of 500 films he only found one giving
this tint; using it with an object he was delighted with the effect ;
happening to put a duplicate object, which, with an ordinary film,
gave exactly the same colours, he was struck with its comparative
poorness. Trying the first slide again, he obtained the same good
result. This difference, he thought, was either owing to the thin
glass cover being at the right axis for the colour, or the glycerine in
which it was mounted exerting an influence. As the neutral films
were so difficult to obtain, he had tried a plan of rotating two films,
the one over the other, and thus obtained the neutral tint, so delicate
in action that its colour varied by the slightest depolarizing influ-
ence of the object examined; and, in addition, gave a display of *
colours more varied and gorgeous than could be obtained by any of the
usual colours employed. At the same time, the rotation of one or
other of the films gave a succession of nearly all the prismatic colours,
so that, if dissatisfied with the neutral tint, a multiplicity of others
could be produced. He had brought with him several selenite stages
which could be tested by the gentlemen present.

Mr. Wonfor, in moving a vote of thanks, said they were not only

200 BIBLIOGRAPHY.

deeply indebted to Mr. Ackland for coming among them, but also for
the valuable information he had afforded them.

Mr. Sewell seconded the resolution, which was carried unanimously:

A very large number of polarizing objects of a varied character
were then exhibited, with and without the selenite stages, by Messrs.
Sewell, Turner, Ackland, C. Smith, Glaisyer, and Wonfor; and general
satisfaction was expressed at the results and the increased beauty with
the neutral background.

Mr. Hennah also exhibited Dr. Pigott’s Aplanatic Searcher,
kindly lent by Mr. Curties, and Dr. Maddox’s photo-casts of diatoms,
ranging from 900 to 3000 diameters, kindly lent by Gen. Worcester.

Mr. Wonfor exhibited a Searcher suggested by Mr. McIntire, con-
sisting of an objective arranged in the draw-tube, with its observing
end turned to the eye-piece, and a simple mode of mounting an
objective under the stage to be used as a condenser, at any angle, as
suggested by Dr. Matthews, and the new slide with movable brass
cover for dry objects.

BIBLIOGRAPHY.

Berichte ueber die Verhandlungen der naturforschenden Gesell-
schaft zu Freiburg von Professor Maier. Freiburg. Troemer.

Untersuchungen ueber die Entwicklung der Empusa musce und
Empusa radicans und die durch sie verursachten Epidemien der
Stubenfliegen und Raupen. Von Dr. Oscar Brefeld. Halle.
Schmidt.

Beitraige zue Anatomie und Histologie des mittleren Ohres. Von
Dr. Gustay Brunner. Leipzig. Engelmann.

Die Sculptur und die feineren Struckturverhaltnisse der Diatoma-
ceen. Von Dr. Gustav Fritsch und Otto Miller. 12 Taf. Mikro-
photogr. Berlin. G. F. O. Miller.

Sitzungsberichte der naturwissenschaftlichen Gesellschaft Isis in
Dresden. Hrsg. Von Carl Bley. Dresden. Schépff.

Sitzungsberichte der Konigl. bayer. Akademie der Wissen-
schaften zu Miinchen, 1870. Miinchen. Franz.

Beitrige zur Theorie der natiirlichen Zuchtwahl von Alfred
Russell Wallace. Translated by Adf. Bernh Meyer. Erlangen.
Besold.

The Monthly Microscopical Journal May11871. PL. LXXXT.

Dorvillia agaricitormas Spiculam

x ON Tin
ALY LL?AL 9

Fig. 4
=
= 5 * ie: | :
=— (Beistes mtermedius * /30 lin. =e eT
Form. of Diso, resulting
Dorsal Ventral Lateral ? trom fig.7.
ELE. Fig.6. Poe: Figce.
| C. Gubité del.

Linear Projection.

THE

MONTHLY MICROSCOPICAL JOURNAL.

MAY 1, 1871.

I.—On the Mode of Working-out the Morphology of the Skull.
By W. Kircuen Parxer, I’.R.S., President R.MLS.

(Read before the Roya Microscopica Society, April 5, 1871.)

A very large amount of information with regard to the structure
of the vertebrate skull may be obtained by the use of the ordinary
methods, maceration, dissection, &c., with the aid of the pocket-
lens. A huge mass of anatomical literature exists in which the
development of the skull has been thus traced, say half-way down-
ward. ‘The value of all this is greatly depreciated by the fact that
the first half of the development processes have not been traced.

Thus we are reading a language only the last twelve of the
letters of which have been seen by us. Even as to mere ossific
centres, a very secondary matter in the structure of the skull, only
about two-thirds of those which may be found in the bird have,
until very lately, been described. In my paper “On the Fowl’s
Skull,” published in the ‘ Philosophical Transactions’ last year, the
skull is traced back to a stage answering to Professor Huxley’s
fig. 57, F' and F’, in his ‘Elements of Comparative Anatomy’
(see p. 138). Later researches on the growth of the skull of the
common frog have shown me that my earliest stage of the fowl’s
skull had already undergone a large amount of metamorphic change.
I can now understand what those changes were, but to make them
plain a series of less mature embryos must be worked out.

For many years my embryonic subjects had been prepared by
being hardened in strong methylated spirit; but this never was
sufficient in the earlier conditions, and I suffered much loss of time
and specimens. Spirit specimens, when examined in section, require
. tobe treated with caustic potass or soda, and then put into glycerine.
In this way fine razor slices can be examined with the quarter-inch
object-glass, and even with the highest eye-piece. 1 generally,
however, use the middle eye-piece. Transverse sections show most ;
and slices passing from before backwards, and thooughly illus-
trated and tinted, show very much indeed. I refer again to my
paper “On the Fowl’s Skull,” in which the original figures have

VOL. V. Q

202 Transactions of the

been copied in a reduced form and tinted by Mr. Geo. West, for
illustration of this remark. But objects hardened by spirit cost
much trouble when they have to be used as solid specimens, and
examined by reflected light; the tissues are not half hard enough,
and they have lost all colour ; so that it is no easy work to make a
dissection from the outside agree, in the mind, with the various
sections that have been made of other specimens at the same stage.
Some tadpoles hardened in dilute chromic acid were given me by
Professor Michael Foster two years ago; these opened my eyes to
the immense advantage of this hardening material. The objects
thus procured are very brittle, but with care the most exquisite solid
preparations can be made by tearing away the skin, and teasing out
the dry, stick-like muscular fibres from amongst the gelatinous tissue
which abounds in the tadpole between the skin and flesh. Then
the colour is so rich ; the deep amber tint makes such objects come
out in reflected light in a way that leaves the mind quite at ease as
to what the eye beholds. Such solid dissections can be made of the
skulls of embryos altogether no larger than a mustard-seed, and
solid sections made both vertically and transversely come out with
exquisite distinctness, corroborating quite what had been determined
from the outside. An embryo thus hardened can be held between
the finger and the thumb, and then the whole creature can be
cloven through, “ from the nave to the chops,” with a sharp razor.
Such vertical sections are easily made by “ an old hand,’ and so are
the transverse slices, to make which I begin at the nose and cut
away rapidly as large a number as possible from the same specimen ;
these are soon valued under the inch lens, and the good ones pre-
served in glycerine between glass, the thick glass receiving a pen-
and-ink mark at the time, which saves time whilst investigation is
going on. Some of these sections are thin enough for transmitted
light ; others of almost equal value show well by reflected light.

I do not examine the sections and dissections which take the
reflected light in glycerine: I preserve them in it, but always wash
it away and put them into water, which allows the reflected rays to
pass through much more easily, and gives therefore a much clearer
view of the object. I nearly forgot to mention that one most de-
hghtful effect of the chromic acid is to give not only the tissues
generally an amber colour, but also the abominable, impenetrable -
“pigmentum nigrum.” Often, in olden times, with spirit prepara-
tions, have I been almost exhausted with attempts to decipher parts
imbedded in this hateful pigment.

A figure in my “Shoulder-girdle” paper, which shows the two
halves of the embryo frog’s sternum,* cost a week’s labour, and
but for chromic acid I should have given up Frog-morphology in
disgust :—how often have I wished that these little savages—

* See plate 5, fig. 4, of that work.

Royal Microscopical Society. 208

cannibals they really are at times—would not lay on their paint to
such a degree. That the tissues which go to form the skeleton
may be well understood, it is very important that a morphologist
should be a good histologist: he not only has to diagnose between
tissue and tissue, he has also to depict other structures than the
connective-tissue series in their general anatomical relations. Brain,
nerves, muscle, glands, skin, mucous membrane—all and every of
their various parts have to be seen, pictured, and described in re-
lation. The skull, above all other parts, is the great warehouse
and factory where all sorts of materials and all kinds of machinery
have to be placed. The skull in its adult form is the most perfect
morphological enigma that can be imagined. Luckily the eyes can
be gouged out, yet they are fastened to the skull by a pedicel in
the sharks and rays; but the ear-sac is always in the way, now
loose, now combined, then loose again: it does what it likes amongst
the real cranial structures, and never is at one stay amongst the
yarious tribes of the vertebrata.

But the nose is the real difficulty and trouble. The ear pos-
sesses its own cartilaginous sac, and although it now marries itself
to this and then to the other, yet its ways and domgs can be found
out with patience; the nasal sacs have nothing to begin with but
membrane, and they borrow this and use that; creeping along one
part and burrowing into another, so that their very earliest fancy
must be known if any account of them is to be given. Thus the
skull itself is largely made up of parts having a diverse origin.
Essentially, in its first membranous condition, it is a “bleb” blown
on to the end of the spinal canal to hold the little sacs that grow
out of the front end of the cerebro-spinal axis.

The vesicles of the brain are superadded to the spinal cord, and
they have to be lodged in a cavity that grows with their growth
and strengthens with their strength. But the upper part of the
axis of the vertebrate animal, after subdividing to form the ver-
tebre, has only an unused piece left, reaching as far as to the
pituitary body: about the posterior third of the skull is thus related
to the vertebree, but as an unsegmented piece. From the vertebrae
rays grow downwards tending to enclose all the thoracico-abdominal
viscera ; but under the head free bars are found belonging to quite
another category of skeletal organs. These carry the gills behind,
and become the face, palate, and forepart of the skull, anteriorly.
The foremost pair of these bars are called the “ trabecule,” or
rafters; they lie above and in front of the mouth, and coalescing
after a time with the vertebral remnant at the back of the head,
form much of the skull.

The second pair form the arch of the lower jaw, and, sending a
secondary bar across to the trabeculx, form what is called the
‘‘ pterygo-palatine” arcade. The third pair of bars are related to the

Q 2

204 Transactions of the

tongue, forming the hyoid arch, and undergoing much metamorphic
change, giving rise on their upper part to the httle chain of ear-
bones—they are only partly bony—whilst a “bung” cut out of
the ear-sac, and running to the “stapes” or stirrup of each ear, is
articulated with this chain. A free process of this chain is attached
to the membrana tympani, or drum-parchment. The four remain-
ing arches of the frog’s face and throat carry their exquisite tufted
gills at first quite free, they then coalesce with each other, and below
also to the third or hyoid arch.

All this is microscopic work; step by step everything has to be
made out by the most delicate microscopical manipulation, and but
for that instrument the whole matter must have been kept secret to
the end of the world. It is impossible to overrate the value of
such means that lead to such researches, for now we begin to see
the absolute Unity of the Vertebrate Series—to say nothing of the
other primary groups of animals. The highest type—the human—
passes through every stage of morphological structure seen in the
series beneath: it does not stop at these stages; it does not utilize,
so to say, the incipient structures that are ready to be so used, but

runs rapidly along its own line, choosing as it were and refusing, -

until at length the perfect man is attained. Yet this perfection of
parts, this production of a creature who in his lowest attributes is
the ‘‘ paragon of animals,” is not brought about irrelatively to the
rest of creation ; it is merely an elected consummation of all that is
highest and best in morphological structure. Does this exclude
“ Teleology,” or the fitness of every part to other parts and to the
rest of the world? I think not.

Royal Microscopical Society. 205

II.—Linear Projection considered in tts Application to the
Delineation of Objects under Microscopie Observation.

By Cuarzes Cusirt, C.E., F.R.M.S.
(Read before the Roya Microscoricat Soctery, April 5, 1871.)
Puates LXXXII., LXXXII., anp LXXXIV.

I wave frequently encountered some difficulty in the endeavour to
interpret many illustrations of objects “drawn under the microscope,”
and this difficulty has arisen from a want of coincidence in the
representation of different views of the same subject under the
varying conditions imposed by a dorsal, a ventral, a lateral view,
a view taken from above or from beneath, and stated to have been
drawn to the same scale. It has been impossible, with the par-
ticulars thus defectively indicated, to interpret the details with
sufficient perspicuity to enable me to arrange them in a consistent
whole, and to construct a correct drawing therefrom, the one view
having proved to be an incorrect representation of another in its
altered position; so that while appreciating the exquisite finish in
the execution of the works in question, I have been disappointed
to find that the drawings have not accurately represented the forms
they were intended to portray; and in selecting particular instances
as examples of such inconsistencies, I desire sincerely to express to
the authors of the same that my sole object is to assist them as
fellow-workers, and not to provoke their animosity.

I beg permission therefore first to refer to two figures illus-
trating Mr. Saville Kent's instructive paper “On a New Anchoring
Sponge,” Dorvillia agariciformis, read at a meeting of this Society
on Noy. 19th, 1870, of which Figs. 1 and 2, Plate LXXXII., are
reproductions; Fig. 1 being a plan, that is to say “ viewed from
above,” and Fig. 2 an elevation of a large bi-ternately terminating
spiculum x 20 linear ; and accepting the plan as correct, we find,
by placing the elevation immediately beneath it, that in this view,
two points only, ¢ and c’, are identical with the positions of their
coincident points on the plan, which will be made manifest by
following the vertical lines projected from the one view to the
other, Figs. 1 and 2.

The extremities of the branches ¢ and a Fig. 2 could, in
their normal state, only assume the positions shown on this figure
under the condition of the axis of the spiculum being considerably
inclined; and accepting the distance indicated by a’ Fig. 2 as a
datum or starting point, it represents the horizontal distance be-
tween these points indicated by # on Fig. 1, and by setting off this
distance x, between parallel lines as at Fig. 4, we get the angle at
which a plane bounding the said points must necessarily assume,

206 Transactions of the

c, a, and a', as well as the angles of the arms and crutches, d, e,
and f, and also the inclination of the axis imposed by such a
position, when by projecting horizontal lines from these points to
intersect the coincident vertical lines continued from Fig. 1, we see
in Fig. 2 where the extremities and bifurcations disagree, and on
Fig. 3, as projected, where they are identical with the several points
on the plan above, which last is submitted as a correct representation
of the spiculum in the position assumed.

The displacement of the several arms and points in Fig. 2 is
just such as would be produced by the employment of a compressor
for the purpose of examination, and under such circumstances I
presume it has been traced by the aid of a camera lucida; and
admitting this to be a correct drawing of the form which was seen
“under the microscope,” I must beg to submit that it is not a
correct representation of that which exists in the tissues of the
animal,

In the next place, 1 have to refer to a rotifer, Gicistes inter-
medius, discovered by Mr. Henry Davis, and described in a paper
communicated by him to this Society in the year 1866, of which
Plate LXXXII., Figs. 5, 6, and 7, are reproductions of the
drawings illustrating the subject ; and a comparison of the several
views will show that some licence has been taken in creating the
figure representing the lateral view of the disk, Fig. 7, for it will
be seen that this is just twice as deep as it is shown to be in the
other two views, Figs. 5 and 6, which are consistent the one with
the other, and that to accommodate such an inconsistency it has been
found necessary to scamp the length of the tube at the top. Such
a lateral view as that of Fig. 7 must necessarily impose in the
others an outline somewhat of the form shown by Fig. 8. This
discrepancy will fully account for the fact of a drawing of the
animal by Mr. Slack having, when placed beside it at the reading
of the paper, “differed widely” from the drawing furnished by the
author. And I must beg, with all due respect, to dispute the
assertion that “both portraits are correct.”

On the other hand, we have examples in which the authors
manifest a precognition of the principles I desire to inculcate, in
the exquisite drawings of Mr. Gosse, illustrating his ‘ History of
the British Sea Anemones and Corals ;’ and in those of another
order illustrating Mr. Hincks’s ‘ History of the British Hydroid
Zoophytes, and even in this last the particular delineation of
Cladonema radiatum, plate XI. of that work, from the pencil of
Mr. EK. W. Holdsworth, elevates it in my humble estimation far
above any one of the other numerous illustrations of that valuable
and highly interesting work.

I do not presume myself to emulate the refinements of the
latter examples, but with the view to avoid the inconsistencies

The Monthly Microscopical Journal, May, 1.1871. Pl: LXXXTUL

Development
OT ae
Melticerta PLTLg ens. RO.

8.

C. Cubitt, del, Tuffen West, so. W. West, amp.

inakersine Proj ection.

Royal Microscopical Society. 207

of the former, I have employed a system of Linear Projection, on
which I now beg to offer the following explanatory suggestions, ~
not however to those my seniors in the service, but more particularly
to younger workers as hints for their guidance, who, while pos-
sessing instruments furnished with good powers, and such accessory
apparatus as the camera lucida or other reflecting media, invaluable
in the case of mounted objects, will nevertheless meet with instances
in which such useful accessories fail to afford the assistance required
for the correct delineation of certain objects ; and I trust that these
suggestions as to the process I employ may, under such circum-
stances, be found acceptable.

In the special instances of tube-dwelling rotifers the difficulty
with a camera is insurmountable, inasmuch as the restraint neces-
sarily imposed upon animals under observation at once obstructs
that freedom of action which is necessary for their assumption of
the expanded state, in which, with their constantly varying atti-
tudes, the employment of any reflector would be wholly inefficient ;
and with the indifferent aptitude which I possess, regarded from an
artist’s point of view, I have had recourse to this system as being
the most expedient to employ. I first make hand-sketches of the
object under observation, and, with the micrometer inserted, measwre
up the work, and then set it out to scale, so to speak, and in so
speaking I must beg permission to use these shop terms somewhat
freely in the followimg remarks as the most expressive that suggest
themselves to a mechanic impressed with an intuitive predilection
for the wheel animalcules in treating a subject which is not sczen-
tific. Should, however, these and other technical expressions, such
as may hereafter be applied, meet the objection of scientific savants
as being mal a propos and indefinite, I can only excuse them on
the ground of their being most convenient terms, as here employed,
to distinguish the different views of an object, and I only trust that
with the working members their adoption may be accepted, the
process understood, and that their employment will not interpose in
elevating the results to a position somewhat higher than that of the
mere mechanical.

But, before proceeding to describe the process, I must beg per-
mission to specify some of the necessary tools and appliances which
—in addition to a good set of drawing instruments—will be found
necessary for the due performance of the work; and these should
consist of a carefully-made drawing-board, a T square provided with
an adjusting stock, for the purpose of producing a repetition of
parallel lines at any other than a right angle, a couple of vulcanite
set-squares, one at an angle of 45° and another at 60°, which also
affords its complement of 30°, to which may be added a few para-
bolic curves; but as to these last it will generally be found more
expedient to set owt on cardboard, and to cut therefrom, such par-

208 Transactions of the

ticular curves as may severally be induced by the projection of any
particular lines in the subject in hand where a repetition of that
curve becomes necessary.

I have selected the delineation of Melicerta ringens as an
appropriate subject for the illustration of this system for several
reasons: the First, from the fact of its being such a general
favourite in the hands of all observers, it may invest the matter
under consideration with an interest that will relieve it of what
otherwise would have assumed a prosaic character. Secondly, that,
notwithstanding the complete and elaborate descriptions, which have
been published on the history of this rotifer, the illustrations accom-
panying the same are all, so far as I am able to compare, wanting.
in that perspicuity necessary to convey an accurate impression of
the appearance of the animal in its natural condition. Thirdly, it
will afford a variety of points in the projection of its several details
that require a very careful application of this system from the
diverse positions assumed by the expanded animal and from the
varying angles to which it is prone to subject the different append-
ages of its head.

The tube, moreover, is a study in itself; and as the several points
in reference to the composition, fabrication, form, and disposition of
the pellets during the process of construction require to be under-
stood, I beg briefly to recount the most prominent of these points
before proceeding to set out the details.

The preliminary act in the formation of the tube of the young
animal is the secretion of a hyaline gelatinous cylinder round about
the body, to which the first crudely-formed pellets are attached at
some distance above the foot; these are subsequently forced by
sudden contractions of the young animal down upon the support to
which the tube becomes permanently fixed, and in some instances
these contractions, by reason of the pressure they create, cause a
departure from the circular form of the pellets in several of the
first laid cowrses, the outlines of which are rendered hexagonal. I
find them, however, more frequently to be indefinitely distorted.

The operation of building is carried on thenceforward to the
completion of the tube, but on many occasions it may be noticed
that the animal having attained its full development persists in
lengthening the tube to an extraordinary extent beyond the limits
actually required by the animal in its adult condition.. Instances
of this I have frequently had under observation, in which the tube
has reached a height of fully twice that absolutely required by
the full-grown animal; and on such occasions Melicerta manifests
that same capacity for inordinately extending the footstalk which
obtains with the floscules, remarkably so in F. campanulata, in-
stances of which have attained the extraordinary height of s5th
inch from the foot-attachment to the incurved summit of the dorsal

Royal Microscopical Society. 209

lobe, the tube at the same time reaching fully up to the neck.
Similar instances occur with F’. cornuta; and that this inordinate
extension with Melicerta is also confined to the footstalk we receive
confirmation in the fact, that during acts of evacuation when the
cloacal orifice is brought to the verge of the lengthened tube, the
body of the animal retains its normal proportions; this abnormal
attenuation being consequently confined to the footstalk.

Much discrimination is exercised by these clever artificers in
the several processes they adopt in the acts of brick-making and
brick-laying ; the heterogeneous mass that is first brought about
the disk by the force of the ciliary currents is seen to pass beneath
a pair of small ciliated processes, which exercise a rapid discrimi-
nation in the selection of those specially adapted for alimentary
purposes and others for the formation of these pelletoid bricks,
which particles, when so selected, are seen to emerge from beneath
the two ciliated processes which conduct this operation, and to
course along the chases beneath the lateral margins of the dorsal
lobe downwards into the pellet chuck or mould, where this granular
matter becomes blended with a cement, secreted during the process
of manufacture, and are moulded by the action of the contained
cilia, by which they are also shaped and finished off in the peculiar
form, resembling somewhat that of the pellets of the Minié rifle,
with this difference, that the sides forming their bedding surfaces
are not parallel, but radiate with their axes from their shoulders to
the centre of the tube.

The pellets are not formed of one homogeneous consistency, but
preserve a central core through the granulate matter of which they
are composed, this core is perfectly transparent on an end view as
represented by Plate LXXXIII., Fig. 14, and a side view which,
by careful adjustment of focus, presents a horizontal section such
as shown by Fig. 15. The bedding surface maintains a tolerably
constant form and proportion, while the more abruptly tapering
outer ends are seen at times to deviate considerably from their usual
shape, and frequently to assume an extraordinary degree of attenua-
tion.

These pelletoid bricks are laid in a peculiar manner, they are
bonded in their horizontal beds, and break joint the one with its
neighbour, so that while there are thirty-two pellets in the whole
circumference, there are sixteen only in each horizontal cowrse,
presenting in elevation perfectly straight and unbroken lines, in-
ducing by such a disposition a series of helices around the periphery
of the tube when the tube is viewed vertically, but any departure
from that position modifies the character of the curve more or less,
according to the degree of inclination, as in the instance before us.

This particular disposition of the pellets in the construction of
the tube ensures great strength, and is eminently calculated to

210 Transactions of the

resist the strains to which it is so frequently subjected from the
concussions of her roving compeers, which horizontal cowrses would
be less competent to withstand, and the first formed portion of the
tube, bemg more densely blended with the gelatinous cement,
assists it, by reason of the resilience so afforded, to yield somewhat
to such shocks, which at this particular pot produce the greatest
effect in tending to rupture the tube.

It will be readily comprehended that the foregoing particulars
impose very delicate manipulation in the several processes involved
in setting out the tube, more especially as it is intended in the
present instance that the top of the tube shall incline somewhat
towards the observer, and as this condition governs the outlines of
every individual pellet of each and every cowrse throughout its
whole length both of the parallel and tapering portions, it demands
our special and attentive consideration; and as the preliminary
operations require to be clearly defined, I will take as a first example
a single pellet more highly magnified, lying on the plane imposed
by the inclination of the tube, and inclined at an angle of 45°.

First draw the pellet in outline on plan at the required angle,
Fig. 1, Plate LXX XIII. Next describe circles representing the
diameters of the shoulder and small end, Fig. 2; then divide one-
half the circumferences into any convenient number of points,
taking six in this instance, of a regular form, which will be given
by the set-square of 30° and 60° (but varying in number and dis-
position in irregular forms according to circumstances), identify
these points on Fig. 2 by numbers from the central point 0 to 6
consecutively, and from each point draw parallel lines extending
indefinitely in the direction in which it is desired to show the
finished view ; then project the points 1, 2, 3, vertically on to any
horizontal line for each end a, b; prick them off on the edge of
a slip of paper and transfer them on to the plan, Fig. 1, when by
projecting vertical lines from each of these numbers from Fig. 1,
their respective intersections with the coincident lines from Fig. 2
will give certain points that limit the outline of the upper half of
Fig. 3, and the lower half being simply the reverse of this, the
continuance of these vertical lines, at right angles with the axis, to
their intersections with the horizontal lines 4, 5, and 6, will com-
plete the figure of the shoulder of the pellet; the small end and
tapering point being set out in a similar manner.

The projection of the complete tube now claims our attention,
and this should be proceeded with by drawing half plans of the
top and bottom, Figs. 4 and 8, at convenient distances from the
position to be taken by the elevation, Fig. 7, first by describing
semicircles cutting the shoulders of the pellets, and to set out
accurately on each of these their radiating axes, when for the sake
of distinction it will be advisable to indicate the positions of the

Royal Microscopical Society. 211

horizontal row by full lines and those of the other by dotted
lines; number them consecutively from the central point 0, and
project these data severally on to planes bounding the top and
bottom of the elevation required, Fig. 7, when by connecting the
points of the top with the corresponding points at the foot, we
arrive at the central positions of each vertical row along the whole
length, Fig. 7.

As the transverse disposition involves a duplicate system, it
will be necessary to set owt a diagram of each layer separately,
Figs. 5 and 6, by constructing the curve these transverse courses
assume from the inclination to be given to the tube, which will be
determined by projecting them horizontally from Fig. 4, ¢ and d,
and transferring the same, each on to a plane representing the top
of the tube at the angle induced by the stipulated inclination, as
shown on the right of Figs. 5 and 6, when the intersections of the
horizontal lines from each of these points, 0 to 8 for the upper, and
1 to 7 for the lower row, with their coincident vertical Imes from
the plan, Fig. 4, will give their central positions taken at their
shoulders, forming the limits of the said curve assumed by the
horizontal layers; then by striking radii from the centres e and /
in each individual instance, we obtain the axial angles of the pellets,
upon which the several outlines for one-half of the elevation have
now to be individually projected, as shown on the left of Figs. 5 and 6.

On the careful execution of the foregoing preliminary operations,
as well as on the accurate projection of every individual pellet on
each axis, must depend the integrity of the finished work. It will
be seen that while the outlines of those of the central row are
circular, those of every row beyond depart by minute but definite
gradations from the outline of a circle to that of the forms inscribed
on the plan, Fig. 4, and although those next adjacent to the central
row may pardonably be represented by circles also, it leaves no less
than seven different and distinct forms, each at a different angle, to
be individually projected for one-half the elevation, in the same
manner, though not necessarily with the same minutiz, as described
for the enlarged view, Figs. 1, 2, 3.

The pellets of the three central rows having been described by
circles, those of the next adjacent have to be alternately depicted
by repeating the several radiating axes obtained on Figs. 5 and 6,
down the whole length of the tube; their points may be determined
by means of vertical lines from the plan, and their shoulders being
at right angles with their radiating axes should be set off at the
several intersections of these axes, with the vertical lines first pro-
jected from the plan, when their diameters may be squared off from
the central line of pellets, by which means we obtain the points
which limit the several outlines all down the tube; the centres in
the one row, and the peripheries in the other, answering as data for

212 Transactions of the

this purpose without involving any measurement whatever, when it
only requires the operator to fill in at his discretion their respective
varying outlines. And here the shifting stock of the T square
comes to our assistance.

The varying proportions of the pellets in the tapering portion
of the tube would at a glance seem to impose the necessity for a
tedious repetition of all the foregoing operations; but ni despe-
vandum, the central positions of any two pellets in their peculiar
disposition are precisely equidistant from their neighbours right
and left, as they also are from each other vertically, or would be so
on a plane surface, the difference due to the circular outline of the
tube being in this instance inappreciable, so that the centres of
the vertical and horizontal courses of the pellets form together a
double series of equilateral triangles all down the tube, whether
parallel or tapering, and by the employment of the set-square of
30° we obtain their correct central positions and resulting diameters
all down the whole length of the tube, thus determining the data
from which all the others have to be projected and set off more
accurately than could be attained by any method of scaling.

The projection of the trochal disk embracing the four frontal —
lobes with their marginal cilia and supporting lgaments, the
secondary range of decumbent cilia terminating in the pellet cup
beneath the dorsal lobe, and the two conspicuous antenne though
less complicated, necessitate an equally careful application of this
system, especially where, as in this particular instance, it is intended
to show the animal at the same inclination as its investing tube, and
inclined also in its horizontal position, so as to relieve it of the too
formal and diagramatic character imposed by parallelism, and hay-
ing selected such an attitude, the several diagrams which have been
constructed from actual measurements, are arranged in the several
positions shown in Plate LXXXIII., which are necessary to produce
the finished form ; Fig. 9 being a dorsal view, Fig. 10 a plan of the
superior lobes, Fig. 11 a plan of the inferior lobes, and Fig. 12 a
lateral view; and it only requires the several intersections of the
coincident points from the different views to be followed, to trace
the outline and prominent features in Fig. 13, which is a rough
outline of the finished drawing, Plate LXXXIYV.

ERRATA IN LAST PAPER.

Owing to certain exigencies which obstructed the proper correction
of the proofs of my paper “On the Winter Habits of the Rotatoria,”
I desire here to explain that page 168 line 10 from the bottom should
read CiustrreD Free; and line 4 on page 169; by means of the
currents it creates.

The Monthly Microscopical Journal Mayllé7l. Pl. LXXXIV.

— Melicerta ringens * 90 —

C.Cubizé del. W. West & Ci se.et op.

—————

Royal Microscopical Society. 213

I1I.—Optical Appearances of Cut Lines in Glass.
By Henry J. Suacg, F.G.S., Sec. R M.S.

(Read before the Royar Microscopican Sociery, April 5, 1871.)

Tue use of high powers in delicate investigations renders it neces-
sary that the microscopist should study the character of appearances
which arise from optical laws, and which can only be rightly inter-
preted by referring them to forms and structures to which they bear
no real or exact resemblance. A short time since the writer called
the attention of the Society to the deceptive nature of the appear-
ances presented by fine cracks in silica films; and further observa-
tions show that if the finest or narrowest of such marks are selected
for examination, the chances of obtaining perfect illusions are in-
creased by the amount of magnification and the perfection of the
objectives employed. Delicate interference bands, pseudo-beading,
&c., iook more real with well-corrected object-glasses than with bad ;
and careful illumination will often add to the structural aspect of
mere optical effects.

The edges of silica cracks, obtained as mentioned in a former
paper, differ from the edges of minute furrows cut in glass, by being
smooth instead of jagged. The latter as well as the former are well
worth study. Preparatory to examining such furrows as are cut
with diamonds in glass for micrometers or diffraction gratings, it is
well to notice the edges of thin glass cut for slide-covers. If half-
a-dozen or more thin glass squares are held close together,* and
viewed, edges upward, as transparent objects, a variety of curious
optical effects will be seen, arising from interfering reflexions and
refractions. The examination should begin with an inch or 2rds,
after which } inch, and } or 3th will be advantageously employed.
It is easy to focus parts of the glasses’ edges, so as to show their
true form; but portions a little in or out of focus will show beads,
appearances like columns of Egyptian architecture, &c. Most of
these optical appearances are sufficiently hazy or confused to give
warning of their true nature; but generally some will be found
so sharp and clear that, if viewed separately, they might easily
mislead a practised observer. In making these experiments, it is
best to have handy a box containing at least several dozens of the
thin glasses, as some sets will prove much more interesting than
' others. They should be viewed with their edges parallel to the
plane of the objective, and also at various angles. ‘The corners of
the squares should also be looked at.

Lines cut in glass for micrometers or diffraction-gratings are

* The stage vice made for me by the late Mr. Thomas Ross. is very handy for

this and many other purposes, as the blades approach each other in a parallel
direction, aud can be fixed at any distance with great nicety.

214 Transactions of the

usually filled up with finely-divided black-lead, and the same mate-
rial has been employed in the writings and patterns made with the
Peter's machine. This substance of course modifies the appear-
ances. ‘To see them in a simpler form recourse was had to Mr.
Ackland (Horne and Thornthwaite), who ruled several sets of fine
lines, each on glass slides, at varying distances, 1—2000”, 1—3000",
and 1—4000", and mounted them with Canada balsam, so that
they could be.safely used with immersion lenses. One set was not
covered or mounted in any way.

Those who have examined very minute writing done by the
late Mr. Farrants with the Peter’s machine will be aware that even
when a very fine diamond-point is used, the incision partakes more
of the character of a scratch than a clean cut. It seems impossible
to cut glass with a smooth, clear edge, such as certain metals readily
give with a sharp tool. A line cut in glass is thus a furrow, more
or less rough at the bottom and sides, and when viewed correctly
under the microscope, has the appearance of a narrow depression
less transparent than the adjacent spaces. It is difficult to get a
really correct view. Even under favourable circumstances of illu-
mination and correction, the edges of a cut are apt to appear as two
raised lines.

Many instructive optical appearances, which might bewilder the
observer if the true character of the object were not known, may be
easily produced, as the following notes will show. The observations
were made with Powell and Lealand’s immersion 3th and Ross’s
y‘jths, condenser aperture 109°. Using central stop A, and vary-
ing inclinations of mirror. Paraffine lamp.

(1a). Cuts as rounded bands ; interspaces flattish furrows. The
bands illuminated on right side, shaded on left. Tint
of lightest part of furrows bluish.

(2a). Flattish bands and rounded furrows, the former slightly
shaded on left; tint of shading bluish.

(8a). Oblique rounded furrows with narrow blue ridges ;
broadish bands with narrower elevated bands up their
centres, light on right side, shaded deeply down the
furrowed side on left.

Same condenser 109°, two radial slots forming obtuse angle.
Angle of mirror varying.

(1b). Broad, flat spaces, narrow, shaded, and elevated ridges.
(2b). Ridges four times as wide as No. 1, with rounded tops.
(3b). Narrowish grooves, something like actual object.

(4b). False ridges, puzzling to count, and hollow.

Same condenser 109°, two rectangular radial slots. Angle of
mirror varied.

Royal Microscopical Society. 215

(1c). Half-round hollows, with rod-like ridges in the middle ;
rounded interspace elevations somewhat lower than
ridges and between them.

(2c). Narrower ridges; nearly flat spaces.

(3c). Appearance of additional ridges, strongly shaded on left.

(4c). Narrow ridges, shaded on right ; flattish spaces, and low
ridges, with narrower shelving shade-spaces down to
ridges, &e., &.

Same condenser 109°; one radial slot, which was rotated to
various angles. Angle of mirror varied.

(1d). Each ent made into a flattish space, with two narrow,
raised edges, shaded on left.

(2d). Cuts made into flattish, ribbon-like elevations, with raised
edges.

(3d). Interspaces raised, with rounded edges; cuts made to
look flattish, and at lower level.

(4d). Appearance of additional and imperfect ridges.

(5d). Series of imbricated and shaded bands.

In the lines cut by Mr. Ackland no attempt was made to pro-
duce the narrowest possible furrows. The width of furrows found
practically convenient for micrometers was only slightly deviated
from, as some cuts were a little deeper than others, and thus caused
the wedge-shaped diamond-point to open the top of the furrows a
little wider. The interspaces of the narrowest were much wider
than the cuts. It is obvious that a cut wide enough to be distinctly
seen, under given magnification, will present to view ¢wo linear
edges, and thus be reckoned as two lines if its true character is not
considered. Cuts very close together may, if the cohesion of the
glass and the perfection of the cutting tool permit, be wider than
their interspaces.

It will be seen that in the preceding statements only one
instance is mentioned of appearances agreeing tolerably well with
the real facts. It must not be inferred from this that it is not easy
to exhibit moderately-fine cuts correctly, or very nearly so. The
object of this paper was to select a number of appearances all look-
ing as if they might correspond with the facts, and all differing
more or less from them.

Those who study the most vexatious diatoms or Nobert’s test-
lines must, it appears to the writer, not only take into account
what they do see, but what they ought to see, provided the object
has a certain definite structure, and certain powers of producing
optical images under given conditions.

VOL. V. R

( 216 )

IV.—Object-glasses and their Definition.
By F. H. Wennam, Vice-President R.M.S.

Unper this title I have no wish to trespass on the patience of the
readers of this Journal. I must, however, remind microscopists
that until quite recently they have been kept in ag ignorance
of the tools they have been working with. uch valuable in-
formation has been hitherto exclusively in the hands of the principal
makers of object-glasses, who years ago, under an implied con-
fidence that I had no immediate intention of divulging any point
that they held as a secret, did not hesitate at a mutual exchange of
information. ‘This time has passed away, and the number of
makers that have since appeared render it no longer possible or
desirable that such knowledge should be confined to the few, but,.
in order to extend the march of improvement, that the question of
object-glasses should now be thoroughly discussed in all its optical
conditions and practical bearings.

From its recent controversial character, some of the information
has been adduced in rather a desultory manner ; at present this
can scarcely be avoided, as a few of the questions mooted still
remain unanswered. The first relates to the Podura. The return
of temperate weather has brought out the insects, and I have now
no difficulty in finding various specimens. I have torrefied some
of the scales for the purpose of gaining some further evidence of
their structure. The method is as follows: the insect is placed on
a piece of velvet, and the thin-glass cover laid on its back. In its
struggles to escape, a quantity of scales will be detached and adhere
to the glass. This is then laid (scales uppermost) on the end of a
piece of thin bright steel (an old worn table-knife will answer well),
and held over a candle till the steel turns to a very dark blue or
purple. The scales will at this heat be completely scorched. Of
course every time the operation is repeated the knife must be re-
polished, in order again to see the right temperature by colour.
After this treatment the scales in a great measure lose their trans-
parency, so that we are far less liable to form erroneous opinions of
structure arising from false refractive figures.

Viewed by the dark field illumination, as obtained by the
parabolic condenser, they no longer appear of the characteristic
blue colour, but are of a reddish-brown tint. The markings are
most decidedly plainer as seen thus opaquely. Most of the scales
have become more or less distorted and curled, like parings of horn
or dried-up leaves. Both at the longitudinal bendings and inclined
sides most satisfactory perspective and profile views may be obtained
of the ribbings or markings, all of which, on both sides of the
scale, run longitudinally without any oblique crossing, and still

Object-glasses and their Definition. 217

retaining their clubbed form; and from the greater distinctness
that is now given to the membrane by the destruction of its trans-
parency, the ribs or markings can be plainly distinguished as surface
elevations. From the brittleness of the burnt scales (which have
been heated nearly to ignition), they are easily fractured. When
this happens longitudinally, it takes place close to the markings, and
follows thew shape, showing that they form a ridge or material
barrier for the line of direction. When the fracture is transverse,
the ridges again offer an impediment as the parting is not a
straight one, part of the markings projecting over and leaving
a corresponding notch in the separated portion. In fact Podura
scales treated in this way leave so little doubt of their structure,
that I think that no one that will take the trouble to try this
simple experiment will admit Dr. Pigott’s interpretation. The
scales can be seen in every possible position; some of them even
curled up point and quill almost together, thus affording an end
view.

That remarkable Podura scale, the Secra Buskii, alone appears
to afford the key to their structure. The ribbings are somewhat
prominent, and the !!! markings so much elongated that only
three or four of them occupy the length of the scale, which is also
very convex, and the intercostal spaces much wider than in other
specimens. By no means of illumination, or any stretch of imagina-
tion, can these markings appear to be caused by the oblique crossing
of ribs on opposite sides. There are some coarse transverse mem-
brane corrugations similar to those which in the finer specimens
give rise to illusory beadings.

Let us not forget how deeply we are indebted to Dr. Pigott for
promoting these researches, who, by the power of negative in-
ferences, has elicited so much practical information, and who first
discovered a waved structure in certain Podura scales, and repeatedly
demonstrated that this might be resolved into ghost beads ap-
pearing as substantial as “ peas in a pod.”

“Tilumination is a vexed question for the photographer, who
has never yet succeeded in displaying the spherules of the Am-
phiplewra pellucida, which so many English observers have seen
microscopically. Unless, therefore, the defining power of photo-
graphy at least equals the human eye armed with the microscope,
no reliable argument can be drawn from its failure or approximate
revelations.” Thus again did the dictum go forth, and shortly
after its echo had crossed the Atlantic, the genius of truth was
invoked, and with the sun for a limner, the desired result achieved,
and so exquisitely sharp and distinct are the lines on the photo-

graph, thus skilfully obtained by Dr. Woodward, that I am tempted
R 2

218 Object-glasses and their Definition.

to ask the question, Has anyone ever seen them directly through
the microscope as plainly as this ? *

Again was the immersion lens delineated in the region of fancy
and romance, and then, by the application of a few commonplace
measurements taken from the real thing, it became known that it
had no property for collecting from a balsam-mounted object a
greater number of rays, but that the limit is the same as in the dry
lens.

“ As it seems right in the eyes of some of the old lovers of dry
objectives to dispute a number of things that they did not learn in
their youth, it may not be out of place to quote a principle at which
advanced optical students are quite aw fait * * * * It would
seem that these writers must be unacquainted with the standard
works on optics, and so of course could not be expected to know
that the angle of total internal reflexion,” &c., &c.

These have been noticed by others as specimens of good taste and
literary courtesy ; I, to whom they were applied, record them but to
forgive them, with the desire that their integrity may rest upon the
merits of work past or to come.

I have carefully examined the aplanatic searcher made under
Dr. Pigott’s directions, and * * * * but avoiding all expression
of disappointment at the result, I add my voice to those that take
the will for the deed, and exclaim, Let us be thankful! +

* T have again to thank Colonel Dr. Woodward for a series of twenty photo-
graphs, which are very remarkable specimens of cleyer manipulation. Ten of the
Podura are illuminated to obtain the beaded appearance, which is most plainly
shown in the scale known under the titles of “ Black Podura,” “Speckled
Podura,” Degeeria domestica, Seira domestica, Degeeria nigromaculata; but, as I
have before remarked, the ‘‘ beads” are developed at the sacrifice of that sharp-
ness and distinctness of outline associated with the note of exclamation
markings. No. VIII. is most distinct, in which the !!! appear with the
“headings,” or, rather, corrugations, not on but between them.

+ “Great things for science have been achieved by means of the microscope,
but these will now be outdone by the aid of an apparatus which the inventor calls
‘An Aplanatic Searcher, and which, when applied to the microscope, increases
its power, its penetration, and capability of definition to an almost incredible
degree. Objects, which under the best of ordinary microscopes appear as black
patches, are seen to be full of beads, or lines, or grooves, or possessed of a fashion
of some sort, with the aplanatic searcher. Some theories of vital organization are
built on discoveries made by the microscope; and if these discoveries now prove
to be delusions, the theories will have to be abandoned or re-written. This is
especially the case with the ‘germ theory” and the theory of spontaneous gene-
ration. The minute disk of jelly in which the germ was supposed to lie is now
proved by tle aplanatic searcher to be a delusion—a false image—due to nothing
more than the imperfection of the object-glass. From this it will be understeod
that a revolution in microscopical science may be looked for. The inventor of this
new and searching apparatus is Dr. Royston-Pigott. A full account thereof will
shortly appear in the ‘ Philosophical Transactions.” Meanwhile, some particulars
have already been published in the ‘ Proceedings of the Royal Society.””—
Chambers’s Journal, Dec. 31, 1870.

Object-glasses and their Definition. 219

I have been trying a number of experiments with various forms
and combinations of lenses in different positions between the eye-
piece and object-glass, but I may state that I do not profess to
have got exactly a similar arrangement to the noted searcher. I
cannot arrive at this without incurring the risk of making a spu-
rious imitation.* But, before entering upon the land of promise, it
will be ag well to note something of what has already been done in
this direction.

At the time when the first achromatics were introduced, Dr.
Goring attempted to obtain achromatism by various combinations
and forms of lenses, intended to act as correctives, placed at intervals
between the object-glass and eye-piece. He admits that he failed ;
nor was success possible, as the arrangement is faulty in its very
principle. From an uncorrected lens or object-glass an immediate
divergence takes place between the most and least refrangible rays
or the violet and red end of the spectrum, the angular separation of
the two rays of course increases with distance, and at length any
form of concave lens will be quite incapable of re-combining them.
It is for this reason that small concave lenses of dense flint have
never been successful when placed half-way down a telescope, having
a single object-glass of crown. The reason for attempting this plan
was to avoid the expense and difficulty of obtaining large disks of
flint glass free from imperfection. Even an excess of thickness in
the back lenses of a microscope will show an appreciable amount of
uncorrected colour, and they are worked as thin as possible in order
to avoid this error ; for artificial achromatism can only be obtained
by the abrupt refraction between two adjoining surfaces. We cannot
imitate the perfection of nature in the eyes of animals, wherein
colour is. corrected by a gradual increase of density. Dr. Goring’s
last achievement was a low-power form of microscope, a description
of which was not published till after his decease; this he termed the
“ Megaloscope.” The instrument was arranged for the purpose of
obtaining a large and flat field; the eye-piece was the ordinary
Huygenian, of low power, and the object-glass proper was composed
of two similar achromatics; but the peculiar feature consisted in a
third achromatic of shorter focus than the others, set in a racked
tube. By separating this, or bringing it quite close to the others,
the power of the instrument could be instantly doubled. About the
same time Mr. Lister made a series of experiments in this direction,
which resulted in the well-known “ erecting glass.” This consists
of two single plano-convex lenses of 14 and 2% focus, with an
interval of three inches; the shorter focus and flat sides are next

* Should a demand render it worth while for any leading optician to construct
the searcher, for his own credit’s sake he would do it properly. But how is this
possible, when no illustrative description has been given from which it can be
made ?

220 Object-glasses and their Definition.

the object-glass. By means of the 2rds object-glass and draw-tube
a power from 5 to 150 may be obtained. From the crossing of the
rays and the formation of an intermediate image, colour correction
was not impaired throughout, though for the best definition Mr.
Lister recommended an increase of distance between the two lenses
in proportion as the draw-tube was extended, and a means was pro-
vided for effecting this. With a 14-inch object-glass, as the tube is
closed the anterior focus becomes lengthened till its distance is
infinite, giving all the grades between a microscope and telescope,
and distant objects may be drawn with the camera lucida. A form
of dissecting microscope was manufactured by Smith and Beck on a
modification of this plan. The draw-tube was moved by a rack and
pinion. On viewing some injections with this instrument I was
struck by its extreme handiness; for, by keeping one hand on the
lengthening and the other on the focussing pinion, all the ranges
from a low to a high power could be instantly made with one
object-glass, and the extent of field gave a great advantage over the
plan of changing the eye-pieces, and the images were sufficiently
“ aristokratic” to make it well worth while to attempt to improve
the arrangement, and to ascertain how far one object-glass of large
aperture may be made to do the work of several powers, for a cheap
form of instrument.

Since the revival of this question I have made a number of
trials of the effects of intermediate lenses, either under or over-
corrected, in neutralizing any errors in the object-glass. Chromatic
correction cannot be obtained this way for the reasons stated, and
out of the numerous combinations that I have tried none have any
material influence in improving the oblique pencils; a 1th with
outward coma had outward coma still with all. If the object-glass
is carefully corrected by the adjusting collar on a covered object,
and any intermediate lens or lenses are then introduced, that cor-
rection will no longer serve, but has to be altered, as the searcher
(so to term it) itself induces an error of correction in the object-
glass, by shortening the posterior or conjugate focus and extending
the anterior one, and the aperture or angle of rays for which it was
specially corrected entering at different incidences to those previous
to the introduction of the intermediate lenses, positive aberration *
is caused; this requires for every difference in their position another
alteration of the adjusting collar. Sometimes the range of this is
not sufficient to produce the required correction—the “ searcher ”
may find a position with an object-glass improperly corrected or
adjusted, or with no means of adjustment at all, in which the defi-
nition may be improved; but in cases where a good object-glass

* Dr. Pigott defines positive and negative aberration as over and under cor-
rection. Fact is the reverse. This may, perhaps, be attributed to a printer’s
error.

Object-glasses and their Definition. 221

has to be thrown out of adjustment for the sake of accommodating
errors from superadded lenses, the investigation does not hold out
much promise, and I regret that in no instance have I been able to .
define any description of error in object-glasses that may lead to their
practical improvement, by the aid of such intermediate lenses, as these
derange the very corrections that the optician has been striving to
make perfect. Hnormous magnifying power may be gained by such
lenses, but in effect this is far inferior to that obtained directly by
high power objectives, and may give rise to illusory appearances.
The inquiry is by no means exhausted, and something may yet
come of it im the shape of an universal microscope, as an improve-
ment upon that manufactured by Smith and Beck. This was almost
exclusively used with a $rds object-glass, rather differently corrected
with an oblique-cut adjusting collar which gave a considerable range
(near 1th of an inch, if I recollect right) between the lenses, which
were to be separated in degree as the draw-tube was extended.

In arecent trial I have found that witha ;4,ths or }th, an erect-
ing glass or intermediate combination consisting of two achromatics of
linch or 1} inch focus with an interval of about 14inch between
them has given the best result. The shorter focus or one nearest
the object-glass should be considerably under-corrected, and the other
over-corrected to a counteracting degree. By altering the distances
between them, the second image formed by the arrangement can be
improved for the aberrations, which vary for every position that
they occupy in the body of the microscope.

The foregoing was written previous to the appearance of the
last number. In reference to actinic glasses, I may state that when
I practised micro-photography some eighteen years ago, I found it
necessary to use object-glasses in which the visual and chemical foci
were coincident in one plane: this I accomplished by adding another
single lens set close behind the others, of a focus suitable for obtain-
ing the result. Colonel Dr. Woodward in using the dry lens,
replaced one of the combinations by another, giving an identical
visual and actinic focus. He states in his recent paper “that the
immersion objectives of high power require no special corrections to
fit them for photographic use, and are the very ones actually
employed.” This is a valuable property of the immersion lens that
has not before been noticed and is correct in theory, for the adjust-
able thickness in the front, which the water film permits, is self-
compensating, and will at once produce the required under-correction
for coincident foci, so that no photographic lines are separate from
the visual ones, and Dr. Pigott’s authority that errors may arise
from this cause cannot be accepted.

( 222 )

V.—Transmutation of Form im certain Protozoa.

By Mercatre Jounson, M.R.C.S.E., Lancaster.
Prate LXXXV.

In the ‘M. M. J.’ for April, 1870, I have ventured to remark
that “ Monas and its congeners became at once important as agents
in removing dead cells, and in their place supplying us with green
verdure which is springing up around us on every side.” Everyone
must have observed that universal greenness which, after the lapse
of a few weeks, spreads more or less over every weather-exposed
surface, large or small. Sir Humphry Davy, writing forty years
ago, says, “ A polished surface of a building or a statue is no sooner
rough than the seeds of lichens and mosses which are constantly
floating in the atmosphere make it a place of repose, grow and
increase.” If we examine a few of the green growths upon these
surfaces differmg from one another in their surroundings, or
“ choses extérieures,” such as moisture, light, temperature, &., we
shall find one composed of a green dust, to which the name of
Chlorococcus has been applied; another, a green scum upon the
surface of a liquid, which has received the name of Euglena; a
third, forming patches of dark green slime upon old walls, and
called Oseillatoria ; a fourth, Lyngbya; a fifth, Vaucherta; a
sixth, Schidzonema, and so on. A more detailed examination of
these separately-named products, and a study of their life-history,
leads to the opinion that they are all (more or less) stages of de-
velopment of some one common source, which it is the object of the
present remarks to identify as the monad, or pin-point source of
life, which has been pointed out by Dr. Bastian and others as the
earliest form in which we recognize living matter.

In a review of nature we are insensibly led to observe an
apparent unity of all its parts into a continuous whole. Thus, in
tracing black to white, we find no point of divergence perceptible
to the senses. Positive electricity only differs relatively from
negative. The animal differs from the vegetable, but the difference
is insensible. In order to establish a view of nature such as is
here proposed, it will be necessary to inquire what evidence we
have before us—first, of a general, and, secondly, of a particular
kind.

Professor Graham, in his ‘Liquid Diffusion applied to Analysis,’
asks, “Can any fact more strikingly illustrate the maxim that in
nature there are no abrupt transitions, and that distinctions of class
are never absolute ?”

In an article called “Higher and Lower Animals,” already re-
ferred to in this Journal, it is said, “Rather may animal life be
likened to a great tree with countless branches spreading widely

The Monthly Microscopical. Journal May 1 1871. Mm Tye

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“

Transmutation of Form in certain Protozoa. 223

from a common trunk, and drawing their origin from a common
root, branches bearing all manner of flowers, every fashion of leaves,
and all kinds of fruit, and these for every use.

“Professor Haeckel looks upon the causes which have led to
the present diversity of living nature as twofold. Living matter,
he tells us, is urged by two impulses—a centripetal, which tends to
preserve and transmit the specific form, and which he identifies with
HEREDITY, and a centrifugal, which results from the tendency of
external conditions to modify the organism and affect its adaptation
to themselves.”* According to M. Famitzen, the gonidia of
lichens, if maintained in a condition of humidity on the surface of
bits of bark for several months, will give rise in their interior to
zoospores, that is, to uniform corpuscles provided with definite move-
ments by vibratile cilia like the zoospores of Algee.t

Mr. Browning? says, “ Many of those who are still sceptical as
to heterogeny admit that they have watched the conversion of bac-
teria into fungoid growths, and some have even alleged that they
have witnessed the conversion of bacteria into infusoria.”

We find in the natural history of Protococcus pluvialis,§ “The
motions of the various forms of Heematococcus are there described,
and appear to be very like those of Euglena viridis; in fact, so
much so that Flotow himself compares them with those of Astasia
pluvialis.”

Griffith and Henfrey say,|| “The forms included under the
family thus characterized are still very imperfectly understood, and
it is probable that some of them, separated generically by Ehren-
berg, are only transitional conditions of others.”

Harvey says,{] ‘We might readily take for a Protococcus or
other simple Alga what are only the spores of a conferva.

“The granules of which the green matter is composed detach
themselves from the mass one after another, and having thus become
free they move about in the vacant space of the joint with an
extreme rapidity.”

Professor Williamson, speaking on Spherosira volvox,** says,
“Tn this stage of its development each protoplasm bears the closest
possible resemblance to an Euglena. The motile condition of the
Protococcus pluvialis, I am convinced that if one of the gemma of
Spheerosira and an individual Euglena viridis were placed side by
side they would be wholly indistinguishable.”

In order to commence this investigation I will append a few
observations I have made on various forms of Paramecium, and I
shall endeavour to show that it constantly transforms to Vorticella,

* Huxley, ‘Academy,’ Oct 9, 1869.
t ‘Quart. Journal of Science,’ Oct., 1869. t ‘M. M. J.,’ July, 1869.
§ Ray Soc., 1853, p. 522. || ‘Micrographie Dictionary,’ p. 75.

{| ‘ Harvey’s Manual,’ p. 29. ** ¢ Pop. Sci. Review,’ July, 1870.

224 Transmutation of Form in certain Protozoa.

and thence passes to Callidina elegans, thus tracing one of the
phases of growth by development from the simple form of Monas to
some of the more complicated animalcule or Entomostraca. I shall
hope in a future communication not only to trace the Paramaciwm
from the monad, but also to show that the “choses extérieures ”
being altered the monad may become a Chlorococcus, an Oscillatoria,
a Lyngbya, a moss, a lichen, an Amceba, or a Mucedo.

There may be many other forms which it may be developed to,
but for the present I must content myself with the changes in
Paramecium to introduce this vast subject fraught with so much
importance to our knowledge of the Darwinian hypothesis, the
question of epidemic disease, and the formation of the green sub-
stratum of Protophyta.

May 20th, 1868, in a liquid containing Oscillatoria and Lyngbya
(May 11th) I observed a Paramecium first divide itself mto two
portions, one globular and the other elongated. They then became
attached, and finally the globular was absorbed by the elongated
portion. The operation was completed in about three or four minutes
(see Figs. 1, 2, 3, 4, 5 and 6).

On May 9th, 1869, I watched a Paramecium divide, as in Figs. 7
and 8, and then swim away, one globular, the other oval (see
Fig. 9).

on the same day I watched two Paramecia, a globular and elon-
gated, become one pyriform body.

Sept. 17th, 1869, I saw the Fig. 10 separate into Fig. 11.

May 9th, 1869, I watched the spot on Fig. 12 slowly disappear,
and the Paramecium become Fig. 13. In further proof that this spot
is caused by contraction of the cell wall, I saw on July 25th, 1869,
the Fig. 14, in which the contraction at the bottom shows the
situation of this spot; but as conclusive evidence I saw the Fig. 15
change its situation, and the contracted spot became visible at a side
aspect, as seen in Fig. 16; and on 9th May I saw several green cells
protrude ameeboid pouches or globules of sarcode from the side, but
more especially the Paramecium represented in Fig. 17.* But now
to come to the proof of what I desire to show in this paper, namely,
that Vorticella is only a stage of Paramecium, and that Callidina
elegans is a developed form of Vorticella, I must refer to Figs. 18
to 21.

Sept. 18th, 1869, I watched Fig. 18 change into Fig. 19, then
throw out cilia at one end, as in Fig. 20, and finally swim away as a
perfect Vorticella, as Fig. 21, with a telescopic stem.f On the same
day I again watched the fissation of a single Paramecium, with two
germinal spots, slowly into two perfect globular bodies, neither of
them having any spot. At the same time, under the influence of
opium, Fig. 22 changed its spot from its position there represented

* See pl. xxv. (fig. 2a), ‘ Micrographie Dictionary,’ by Griffith and Henfrey.
+ I have often in previous observations seen the telescopic tail protruded by
objects having all the appearance of a detached Vorticella nebulifera.

Transmutation of Form in certain Protozoa. 225

to that indicated in Fig. 23; at the same time the film represented
appeared as a perfect membrane, quite transparent outside the cilia—
a globule of sarcode.

Sept. 22nd, 1869, I watched Fig. 24 become Fig. 25, with cilia
at each end; subsequently it assumed the appearance at Fig. 26, and
finally ‘swam away as a perfect Paramecium as Fig. 27.

July 3rd, 1870, I watched Fig. 28 become Fig. 29, and sub-
sequently Fig. 30. In the same liquid I found Figs. 31, 32 and 33,
all of which I believe to be modified forms, transitional from some
forms of Paramecium, such as Kolpoda eucullus to Vorticella. During
the same observation I saw a Vorticella contracting its investing
membrane in all directions like an Ameba, and a change which gave
me much pleasure, a decided Paramecium (Fig. 34) change to an
equally decided Vorticella (Fig. 35). I also saw Fig. 36 change the
end at which the cilia were working and become Fig. 37, and Fig. 38
working cilia at each end successively: also a transparent body
resembling a colourless Euglena change shape as Figs. 39, 40, 41 and
42, as if to become a Vorticella.

July 26th, 1870, I found Figs. 48 and 44 among a number of other
forms in the pellicle formed on a liquid containing Vaucheria clavata.

July 24th, 1870, I found a Vorticella, apparently intermediate be-
tween Paramecium and Callidina elegans, closely resembling Fig. 47.
But on July 26th I watched Fig. 47 change first to Fig. 48, then to
Fig. 49, and finally swim out of the field as Fig. 50. Fig. 51 repre-
sents a Paramecium, with a tail like Vorticella—this I saw on
April 26th, 1868. On Aug. 13th, 1870, I watched Fig. 45, a decided
Paramecium, change to Fig. 46, an equally decided Kerona.

Some few years ago, during my early observations, before a date
was affixed, I made the drawing, Figs. 60, 61, 62, 63 and 64, from
Vorticellee, which I had watched.

It now simply remains for me to give my reasons for thinking
Callidina elegans as merely a developed form of Paramecium.

March 26th, I saw Fig. 52, which from former observations I am
sure is only the closed form of Figs. 58 and 59.

July 23rd, 1870, I saw Fig. 53 change to Fig. 54, both of which I
believe to be closed form of the same animal, But on March 26th I
saw Fig. 55 unfold itself and become Fig. 56. I watched it assuming
all the shapes of Callidina elegans, for about five minutes. Fig. 57 is
only another shape which the creature assumes, as also Fig. 58. I
have made numerous drawings of these creatures, and in some cases
I have drawn undoubted Paramecia ; but the shape and movements
are so similar that I have no doubt that subsequent research will
show these various animalcule and Infusoria to be simply stages of
development of one and the same thing, and that is the monad con-
dition which owes its origin to the chlorophyll of vegetables and the
germinal matter of animal cells.

The plate which I have attached not: only contains no new
forms, but the markings are in many cases indefinite ; but feeling
convineed, as I do, that many if not most of the body-markings are

226 Microscopical Examination of Two Minerals.

the temporary contraction of sarcode, I have purposely avoided
drawing them. Moreover, in such a class of researches as the
present, where changes were almost momentary, it was only pos-
sible to draw from the best memory, as the lifting the eye from the
lens to make the drawing on the spot would have been to forfeit the
more important information—the change which might take place
whilst engaged in the act of drawing.

It has been chosen to draw attention to this subject of trans-—
formation through the agency of Parameeciwm for several reasons :
Ist. It is a common subject of observation, and may be readily ob-
tained. 2nd. It is larger than Monas, and the changes are more
easily observed and less liable to mistake. 3rd. I have more
drawings of changes observed in this than any other infusorium.
Moreover, if the principle is allowed, one stage of transformation is
as good as another.

It would, no doubt, have been more systematic to trace the
subject at once from Monas along the line up to Paramecium; but
here, until the principle is allowed, much difficulty would have
beset our inquiry, which is obviated by the use of Paramecium to
endeavour to establish the rule.

In observing on the unity of nature, which seems to be pointed
at by this and other facts especially noticeable, while making our
investigations on that debatable ground—the margin of Protozoa—
we are insensibly led to feel that the orb at least in which we dwell
is in an especial manner—

“Totus teres atque rotundus.”

VI.— Microscopical Examination of Two Minerals.
By Prof. A. M. Epwarps.

THERE was exhibited, at the last meeting of the Lyceum of Natural
History of New York, two specimens of minerals which, on account
of their peculiar characters, seeming to indicate that an examination
by means of the microscope would reveal facts of interest connected
with their source and origin, were referred to me for investigation
in that manner. I have viewed them by means of the microscope,
and now report upon them as follows :—

The first is a specimen of marble reported to come from a spot
‘on the Adirondack and Lake George Railroad, near Thurman’
Station, Warren County, and about twenty-five miles from Saratoga
in this State, New York, and was polished so as to show its texture
very well. In colour it is white, mottled with light green, and

Microscopical Examination of Two Minerals. 227

having scattered through its mass large patches of transparent, so-
called, Noble Serpentine. Mr. G. M. Wilber, who contributed the
specimen, was not acquainted with the exact locality, but Prof.
D.S. Martin recognized it to be identical with some in his posses-
sion, from that portion of New York State indicated.

Without any special preparation and examination, by means of
a simple lens alone, the whole mass was seen to consist of Hozdon
Canadense in a remarkably fine state of preservation. Subsequently
I cut slices from it and ground them thin enough to permit suffi-
cient light to pass through, so that the microscope with higher-
power lenses could be employed in studying it. Some specimens I
acted upon by means of dilute hydrogen chloride (muriatic acid),
and compared with very beautiful specimens of the original Hozdon
Canadense from Canada, and for which I am indebted to my fellow-
member, Dr. L. Feuchtwanger. These specimens from both locali-
ties, as well as illustrative plates, I exhibited, so that all might see
and confirm my discovery, which must be considered as one of con-
siderable importance, when viewed from a geological point of view.
It may be observed that the New York specimens are very much
finer than the Canadian ones, that is to say, they show the structure
of this foraminifer in a strikingly-clear manner, and this the more
particularly after the action of the acid. At some future time I
may take an opportunity of entering into a consideration of some
points connected with the structure and affinities of Hozion Cana-
dense, for in this material thus fortunately brought to light, we have
extremely favourable opportunities of studying its intimate anatomy.
This I will have a better opportunity of doing when I receive
further supplies of the material, which I am endeavouring to pro-
cure, and which is said to occur in large quantities at the point
from which this was brought.

It is well known that the presence of this fossil is considered to
indicate that the rocks containing it bélong to the Laurentian
group or period, and the bringing of them over the border and down
thus far into New York State is of great geological importance.
This is the more so, as the members of the Canadian Geological
Survey have only lately traced these rocks down into New England,
as far, at least, as Salem, Massachusetts.

The other specimen referred to me for examination by means of
the microscope, and chemically if found necessary, is the lump of
nearly white material exhibited by Mr. J. W. Ward, and thought
by him to be finely-pulverized mica, and said to come from a bed of
clay in the State of Delaware. At the time of its exhibition I
expressed my strong conviction that it consisted of the silicious
skeletons of Diatomacez, and my suspicions have been confirmed.
In fact, strange to say, it proves to be a mass from the now well-
known deposit existing at Six-mile Caiion, near Virginia City, in

228 Microscopical Examination of Two Minerals.

the state of Nevada, and some of which, under the name of “ Electro-
Silicon” was exhibited by another member at the same time. At
this locality this remarkable material is reported to occur in the
form of a stratum several hundred feet in thickness. It is rather
hard and stony, so it is ground down to a fine powder, and then
comes into commerce as a polishing material, and has been rather
fancifully christened “ Electro-Silicon.” It is an example of the
kind of deposit I have had already to allude to as Sub-Plutonic,
examples of which are so common all through our Pacific States.
At some future time I will have something to say concerning the
genesis of these deposits.

We have in these two examinations, which I have been enabled
to make, further evidence, if it were necessary, which fortunately it
is not, of the value of a knowledge of the means of employing the
microscope to the geologist; for, using it, facts have been thus
readily and in a few minutes settled, which no chemical or other
analysis, taking perhaps hours to perform, would indicate.— From
Proceedings of Lyceum of Natural History, New York, U.S.

( 229 )

PROGRESS OF MICROSCOPICAL SCIENCE.

The Lymphatics of the Lungs.—An investigation into these struc-
tures has been recently undertaken in M. Chrzonszezewsky’s labora-
tory at Kiew, by Herr J. Sikorsky. The results have been published
in the ‘Centralblatt’ of December 3rd, 1870, and are abstracted in
a recent number of the ‘Lancet’:—The method adopted consisted
in the injection of a watery solution of ammonia into the lungs of
living cats and dogs, and the subsequent examination of the paths
pursued by the tinted fluid, the lungs being at once removed from the
body and frozen, and the "plood-vessels being in most cases injected
with a solution of gelatine tinted blue. In such experiments it was
found that, in opposition to the effect produced in dead animals,
neither the intercellular substance, nor the cell formations, not even
the columnar epithelium of the bronchia, with which the carmine
solution must have been in direct contact, became tinted. The com-
mencement of the lymphatic system was not exactly the same in the
bronchia and the alveoli of the lungs. In the bronchia the epithelium
generally remained uncoloured ; but between the columnar cells were
special structures, very similar in form to theso cells, and staining
strongly with carmine. From these structures minute canals pene-
trated perpendicularly to the surface of the mucous membrane, and
formed a close plexus in the submucosa, and partly also in the
mucosa, from which larger trunks originate, which accompany the
bronchia to the roots of the lungs. In the alveoli of the lungs, on
the other hand, a peculiar plexus, composed of tubes and nodal dilata-
tions, is found; the latter are triangular, stellate, or irregular cavities,
which are again connected with the lumen of the alveoli by means
of very fine tubules. The lymphatic plexus of the alveoli gives
origin to larger vessels, which accompany the veins to the roots of
the lungs. This system constitutes the so-called deep plexus of
lymphatics of the lungs. The superficial plexus arises from the
subpleural alveoli. The trunks pass into the pleura, and then into
the pulmonary ligaments.

The Origin and Nature of Fat.—In the ‘ Transactions of the Vienna
Royal Academy,’ Herr Toldt has recently published some very interest-
ing observations: In opposition to the statements of Virchow, who
maintains that fat-cells are to be regarded as the cells of connective
tissue filled with an oily fluid, and are therefore constantly associated
with this tissue, Toldt gives as the general results. of his inquiries
upon the intra-spinal fatty tissue that this, at least, is an organ of a
peculiar nature, which neither in regard to its structure nor function
can be included amongst the connective tissue formations. In order
further to demonstrate that adipose tissue is independent of connective
tissue, he refers to the characters and relations of fatin the Batrachia.
The masses of fat that surround the uro-genital apparatus of these
animals in the larval state consist of large, round, transparent nu-
cleated cells, not separated by any intervening substance except blood-

230 PROGRESS OF MIOROSCOPICAL SCIENCE.

vessels. Passing to the Mammalia (says the ‘ Lancet, from which we
quote), he points out that the first formation of fat in the embryo
occurs round the kidneys, and thence gradually extends into the con-
nective tissue of the mesentery after birth. He considers a strong
argument in favour of the independency of the adipose tissue to be the
fact that it always has, down to its smallest lobules, its own proper
and closed system of blood-vessels, which, it is curious to observe,
very closely resembles that of the acinous glands. These researches
of Toldt enable us to explain the absence of fat in regions where
everything appears to favour its formation, as in the sub-muscular con-
nective tissue of the intestinal canal. It explains also the persistence
of the tissue, with its characteristic features, even when all the oily
matter has been removed by absorption. Whilst fully concurring in
the general statement that fat-cells possess in mature adipose tissue a
distinct membrane, he differs from Czajewicz in maintaining that
when first formed they are destitute of a membrane, this only becom-
ing visible in the later embryonal periods. The minute masses of
protoplasm they contain, however, remain throughout life. He makes
an interesting observation to the effect that spring frogs that have
fasted through the winter, and are excessively lean, present fat drops
in which no membrane is distinguishable, but which, reduced to their
protoplasmic primary mass, possess the power of amceboid movements.
From the consideration of these facts, M. Toldt has arrived at the
conclusion that the protoplasm of the fat-cells, when supplied with
sufficient nutriment, is capable, like a gland-cell, of forming fat as a
kind of secretion; and, inversely, when the consumption of oxidizable
material exceeds the supply, it possesses the power of using up the
stored-up fat and discharging it into the blood. The mode in which
fat is laid up has also been investigated by Fleischer, with a view of
determining whether, in accordance with Liebig’s idea, the amylaceous
compounds ingested are converted into fat directly ; or whether, as
Voit thinks, the fat consumed in the economy is derived from the fat
of the food, and that the amylaceous compounds are only serviceable
as readily combustible ‘compounds, by means of which the fat de-
veloped from albuminous compounds, and already present in the
body, are preserved. 'The results of his investigations on cows, which
were both numerous and extended over a long period of time, were on
the whole unfavourable to Voit’s views.

Presence of Fungi in the Kar.—Dr. Karsten has a paper on this sub-
ject, accompanied by numerous illustrations, in the ‘ Bulletin de la
Société Impériale’ of Moscow (No. I., 1870). The author confirms
the statements of Hallier and other previous observers, that when the
spores of these parasitic fungi are sown elsewhere, the plants which
result from them assume very different forms, according as the sub-
stance on which they are sown is rich or poor in material for nutri-
tion ; and that fungi described as distinct species, or even as belong-
ing to different genera, are merely different genetic forms of the same
plant.

The Ovipositor in Bristle-tails and Spring-tails.—The last number
of the ‘American Naturalist’ contains an extremely able though

PROGRESS OF MIOROSCOPICAL SCIENCE. 231

popular paper on the subject of Bristle-tails and Spring-tails. Mr.
L. 8. Packard, jun., the author, describes among other structures one
which appears novel. He is disposed to consider it an ovipositor.
In the genus Achorutes, it may be found in the segment just behind
the spring-bearing segment, and situated on the median line of the
body. It consists of two squarish valves, from between which project
a pair of minute tubercles, or blades, with four rounded teeth on the
under side. This pair of infinitesimal saws remind one of the blades
of the saw-fly, and he is at a loss what their use can be unless to cut
and pierce so as to scoop out a place in which to deposit an egg. It
is homologous in situation with tne middle pair of blades which com-
pose the ovipositor of higher insects, and if it should prove to be used
by the creature in laying its eggs, we should then have with the
spring an additional point of resemblance to the Neuroptera and
higher insects, and instead of this spring being an important differen-
tial character, separating the Thysanura from other insects, it binds
them still closer, though still differing greatly in representing only a
part of the ovipositor of the higher insects.

Photo-micrographs for the Stereoscope.—Dr. R. H. Ward has been
reading an important paper on this subject before the Troy (N. Y.)
Scientific Association. Certainly stereoscopic views of microscopic
objects ought to be very popular, and would, if properly taken, prove
most valuable to the student. Hence we think Mr. Ward’s instruc-
tions worthy of note. He states that in order to photograph, without
delay, any field of view which a working microscopist deems worthy of
preservation, he should have a camera mounted on a plank which is
blocked at one end for the feet of the stand used as a “ working instru-
ment.” Then, whenever desired, the eye-piece is removed, the instru-
ment levelled into a horizontal position and placed accurately on the
plank, and the magnified image instantly thrown upon the focussing
plate of the camera. Finding the usual band, passing around pulleys
and over the fine-adjustment wheel, to be a slight annoyance in carrying
out this plan with the stand he ordinarily uses (a large stand of the
“ Jackson” model), he makes the fine-adjustment by a somewhat soft
cylinder of india-rubber lying upon the wheel. This cylinder is
rather more than three inches long, is an inch and a half in diameter,
and weighs about four ounces. It is open through its centre, like
a tube with thick walls and small bore, and is mounted upon one
end of a straight, light, wooden rod, the other end of which is sup-
ported on or near the top of the camera. Itis prevented from rolling
off from the fine-adjustment wheel by a horizontal wire, transverse to the
axis of the apparatus, attached by a hinge-joint to a post at the side of
the plank, and to a pin in the end of the wooden rod which just passes
through. the cylinder; and being retained not over the e¢entre, but
somewhat to one side of the wheel, loss of motion is simply impossible,
and an extremely fine and manageable motion is secured. The un-
equalled facility and certainty with which this apparatus can be
instantly laid upon the fine-adjustment wheel, or turned back from it,
is sufficiently evident.

VOL. V. 8

232 PROGRESS OF MICROSCOPICAL SCIENCE.

Approval of Col. Woodward's efforts—The Medical Society of New
York has recently passed a resolution expressing its interest in, and
appreciation of, the microscopical work of the United States Army
Medical Museum at Washington. The Society approves, with some
degree of enthusiasm, the methods of investigation and of disseminating
results, employed at the Museum, especially in regard to the study of
healthy and diseased tissues; believing that the progress attained is
of material use to the profession, and that it would be unattainable at
present without the unusual facilities furnished by the Government.
We regret that America is so far ahead of this country in this respect,
but we cannot avoid thanking Dr. Woodward for the great value of
his labours and for the courtesy with which he treats all micro-
scopists in his own country and in this.

Parthenogenesis in the Pupe of Insects—There appears on this
subject an able paper, by M. O. Von Grimm, in vol. xv., No. 8, of
the ‘Memoirs of the Academy of St. Petersburgh.’ It is a curious
instance of Parthenogenesis in a species of the dipterous genus Chiro-
nomus. Like the well-known case of Miastor, discovered by Prof.
Waener, this is an example of reproduction by an insect in one of its
preparatory, and therefore sexless stages, called Peedogenesis, by Von
Baer. The formation of the egg-like reproductive bodies commences
in the larve; but the eggs are not extruded until the insect has
passed into the pupa state. It appears that in the spring the larve,
produced in the ordinary way from eggs, grow rapidly, and after the
third change of skin attain their full size and show distinct traces of
the pupa within them. The eggs are produced direct from the pupa
in this condition. In the autumn the course of development during
the preparatory changes is precisely the same; the pupa, however,
changes into the imago, which deposits the eggs, probably after copu-
lation, in the ordinary manner. The mode of development of the
eggs and ovaries, and that of the embryo in the egg, are described
by the author at considerable length, and illustrated by good figures.
The eggs are developed in the same way, both in the spring and in
the autumn, although in the one case they will be deposited by the
pupa, and in the other by the imago; and as they present no differ-
ence in their structure, the author regards them all as eggs, and
rejects the distinction into ova and pseudova. He seems inclined
to adopt the notion that the supposed cases of Parthenogenesis may
be due to self-fecundation.

The Regeneration of Epithelial Formations has been lately investi-
gated by Herr Julius Arnold. He has sought to establish experimen-
tally the source of epithelium in the formation of new skin from
granulating wounds. His observations were made upon the cornea,
the tongues and the epidermis (web) of the living frog, and upon the
mucous membrane of the hard palate, and upon the scalp of the dog.
Arnold failed to confirm the prevailing notions regarding the forma-
tion of these cells, by scission of pre-existing epithelial cells, or by
genesis from connective-tissue structures. In precisely those points
in which the regeneration of epithelium was most active, epithelial

PROGRESS OF MICROSCOPICAL SCIENCE. Doe

cells with multiple nuclei, or in the act of division, were most rare.
When the wound was left to itself, the formation of epithelium took
place at the periphery, thence advancing toward the centre. Yet,
when this was prevented by the removal, in a granulating wound of
the hard palate of the dog, of all the peripheral tissue, including the
periosteum, the formation of central islets of epithelium was not pre-
vented. The same results were obtained in wounds upon the scalp of
the dog.—Virchow’s Archiv, Vol. XLVIL, Part IT.

What is the Use of the Spleen ?—This question is, we fear, yet un-
answered, though Signor Bacelli has attempted its solution. He
observes that in the intermissions of the first attacks of malarial fever
there is frequently a great increase of appetite, which, however, is
soon followed by a gastric catarrh, leading to a very complete loss of
digestive power (known even to Celsus) for albuminous compounds.
His researches have led him to believe that the increase of appetite at
the commencement of the disease is due to simple hyperemia of the
spleen; whilst the disturbance of digestive power, occurring after
repeated attacks, was attributable to the persistent hyperemia of the
organ producing physiological disturbance of its functions. The large
veins of the spleen, he points out, are destitute of valves, and pass,
imbedded in the pancreas, and therefore imbedded in the stomach,
and in front of the spinal column, to the liver, so that the blood only
traverses them unimpeded when the stomach is empty; whilst, when
the stomach is full, the blood current is more or less completely
arrested. During digestion, physiological enlargement of the spleen
occurs; and, partly owing to the contractility of the organ, and partly
to the pressure by the stomach on its veins, its blood is returned by
the vasa brevia and coronary veins. But he has found that from the
splenic pulp, and from its venous blood, a juice can be obtained con-
taining pepsine, and capable of digesting coagulated albumen. The
spleen, he is therefore disposed to think, prepares from the disinte-
grated albuminates of the blood-corpuscles the pepsine that is after-
wards secreted by the glands of the stomach. The hyperemia of the
spleen occurring at the commencement of the malarial intoxication
occasions an increased secretory activity of the gastric peptic glands,
and thus accounts for the increased appetite observed at this period;
but, at a later stage of the disease, the persistence of the hyperemia
causes stasis of the blood in the swollen spleen, accompanied by a
kind of paralysis or functional disturbance, and the patient is no
longer capable of digesting albuminoid food.

The Range in Time of the Foraminifera.—At a late meeting of the
Geologists’ Association (March 3rd, 1871) Professor T. Rupert Jones,
F.G.8., read a paper on the above subject. The paper (says the
‘ Geological Magazine’ for April) was preceded by an interesting viva
voce recapitulation of the more noticeable features of the Porcellanous
(imperforate), the Hyaline (perforate), and the Arenaceous, Foramini-
fera, the more important genera of which groups were illustrated by
a fine series of diagrams. The variations of form of the Foraminifera
are innumerable, and it is extremely difficult to construct satisfactory

s 2

234 NOTES AND MEMORANDA.

species and genera. In a strict zoological sense, indeed, a Forami-
niferal genus has but the value of a species of a higher class. The
tables and lists of genera prepared by the Professor might therefore
be compared with lists of species of the higher divisions of the animal
kingdom. Of the Porcellanous group, Miliola, Nubicularia, and Cornu-
spira appear to have the longest range, being found in Triassic and
Rheetic strata, and living in our present seas. The Arenaceous are
older, five genera occurring in Carboniferous formations. Of the
Hyaline Foraminifera, seven genera are Paleozoic. Fusulina, Stroma-
topora, and Hozoon appear to be essentially Paleozoic forms. The
essentially abyssal genera are Arbulina, Globigerina, Pulloenia, and
Spheroidina, all Hyaline. The Globigerina, as is well known, being
abundant both fossil in the Chalk and living in the bed of the At-
lantic. Contrary to the general impression, there are very few forms
common to the Atlantic ooze and the Chalk, and this leads the author
to doubt some conclusions which have recently been drawn. Pro-
fessor Morris exhibited some of the Foraminiferal mud from the
bottom of the Atlantic, and pointed out the important part the class
has played in the formation of the globe, reminding the Association
that Hozoon forms masses of rock covering a vast area in North Ame-
rica, that Russian Mountain Limestone is made up of Fusulina, that
the Nummulitic Limestone, of which the Pyramids are built, is found
over a very great extent of the earth’s surface, and, as Lonsdale was
the first to show, our world-famous chalk cliffs are chiefly composed
of the remains of this curious group of the animal kingdom. Finally,
Prof. Jones explained the method of successive boilings and siftings
of obtaining the fossil Foraminifera from clays.

NOTES AND MEMORANDA.

The Library of the late Professor von Grafe is in the possession
of Hirschwald, the well-known Berlin publisher and bookseller, who
is about to publish a catalogue of it. There are doubtless books on
histological matters among the series.

Another District for Eozoon.—At a late meeting of the Lyceum
of Nat. Hist. of New York, Mr. G. M. Wilber exhibited a specimen of
green and white mottled marble, from near Saratoga, New York,
which was recognized by Prof. Edwards, as consisting of Hozdon
Canadense. The specimen was referred to Prof. Edwards for exami-
nation and report.

Fresh-water Diatomacee or Infusorial Earths.—Prof. A. M.
Edwards recently read a paper on this subject before the New York
Lyceum of Natural History. The earths are either of marine origin
or lacustrine. Such deposits, says the writer, are extremely common
in this country, as well as in Europe, and are generally of a light

NOTES AND MEMORANDA. Bao

grey colour, or perfectly white, and extremely light and pulverulent
in texture. On the Western coast, through California, Oregon,
Washington territory and Nevada, there exist vast tracts covered by
fresh-water deposits of Diatomacez, which are hard and stony. They
have become so by the action of superimposed lava and basalt. Now,
it is a remarkable fact that there have come to light two deposits
from the Atlantic coast, possessing very much the same physical cha-
racters as these Western strata; that is to say, they are hard and
stony, and almost white in colour. One of these was presented at a
meeting of the Lyceum some time since, by Dr. L. W. Feuchtwanger, but
unfortunately its exact locality has not been ascertained. The other is
from New Hampshire, and all of the facts connected with its manner
of occurrence, doubtless will be brought to light, as Prof. Edwards is
at present engaged on the microscopical department of the geological
survey of that state, now being prosecuted under the superintendence
of Prof. C. H. Hitchcock. A very extensive lacustrine sedimentary
deposit of the pulverulent kind, and almost white in tint, has been
discovered on the shores of Lake Umbagog, in New Hampshire, and
there were indications that it extends beneath the waters of the lake,
perhaps over the whole bottom. These deposits are of interest, geolo-
gically and microscopically, but at the same time commercially, as they
have been used to some extent, not only as polishing powders, but as
a source of very finely divided silica, of which the skeletons of the
Diatomacee they contain are made up, for the manufacture of soluble
silicates, or “soluble glass” as it has been called, which is now a
considerable article of trade. Although existing for the most part in
strata of no very great thickness, or usually covering no more than a
few acres of ground, yet, as the number of localities from which they
have already been procured in the Atlantic states is over a hundred,
the supply for commercial purposes is amply sufficient, without having
to draw upon the vast tracts covered by the lake deposits of the
Pacific coast, or the marine strata of California and Virginia. In a
forthcoming volume of the Report on the Geology of California, the
whole subject of these deposits, their mode of formation, with descrip-
tions and figures of the organisms found in them, will be published,
when will be cleared up several points of interest with regard to
them.

‘The History of Zoology,’ by Victor Carus, is already in great
part printed.

Rocks and Dredgings from the Gulf Stream.— These have re-
cently been chemically examined by Mr. 8. P. Sharples. From a
. Inicroscopic examination of some of the bones, he says that there was

little but fibrous structure remaining. They were of a Manatee.

Monochromatic Light.—A correspondent, who does not give his
name, and whose letter we therefore cannot insert, inquires what is
meant by this term. We really did not think there was any difficulty
about the matter. It simply means light of a single colour: thus,
red, blue, or yellow light, would be monochromatic. We think Col.
Woodward explains the matter sufficiently. At page 153 he says,

236 CORRESPONDENCE.

“ T use ordinarily a solution of the ammonio-sulphate of copper, which
gives a bluish-violet light, approximating monochromatism sufficiently
for all practical demands.” If the rays of ight which fall on the
mirror of the microscope are previously sent through this solution
the whole thing will be achieved. We trust we have rendered this
sufficiently clear to an “ Amateur.”

CORRESPONDENCE.

Portion AnD Numer or THE Cruia In Cicisres.
To the Editor of the ‘Monthly Microscopical Journal,

Sr. James’s Mount, LivErpoot,
April 15, 1871.

Srr,— Will you allow me to correct Mr. Charles Cubitt’s statement,
made in the concluding paragraph of his recent paper “ On the Winter
Habits of the Rotatoria,’ reported in your last number.

As to the charge that I was “unable to detect the second wreath
of cilia on the lobes of the tube-dwellers,” it is most singular that he
could overlook the following paragraph (page 42 of the Journal for
January last) :—

“ Mr. Chantrell pointed out a marked characteristic in the mature
specimens of the Aicistes crystallinus, which is the second row of cilia,
carrying the food in right and left currents to the gullet or mouth:
this does not show in the young specimens, which are always in tubes,
but as they get larger the tube gradually disappears.”

Further, I exhibited at that time a large drawing I had made of
the Cicistes crystallinus, contrasting the illustrations of this animal,
copied from Pritchard’s ‘ Infusoria,’ the ‘ Microscopical Dictionary,’
Slack’s ‘ Marvels of Pond Life,’ and from the drawing of Cicistes inter-
medias accompanying Mr. Henry Davis’s (F.R.MS.) paper “On icistes”
(published in the Royal Microscopical Society’s ‘ Transactions’), with
my drawings from life of old and young Hicistes, showing in Fig. 1 a
well-defined second wreath of cilia, and none in the others. This draw-
ing I have had photographed, and I herewith send you a copy.

Some months ago I sent Mr. Davis several specimens of icistes,
as also of Floscularia, from the Windsor pond. We were both clear
about the second row of cilia, but differed in opinion as to whether the
cilia were inside or outside the disk, I believing the former.

Mr. Davis (whom Mr. Cubitt quotes as an authority on tube-
dwellers) quite agrees with me that there is an entire absence of the
transparent tubes in the Floscularia I sent him.

I am, Sir, yours truly,

G. 'T. CHANTRELL.

[Mr. Chantrell has sent a series of photographs, which, however,
it is quite unnecessary to reproduce.—Eb. ‘M. M. J.’]

PROCEEDINGS OF SOCIETIES. Fat

Tur ‘AMERICAN JOURNAL OF Microscopy.’
44, Lake Street, Cuicaco, March 20, 1871.

Henry Lawson, M.D., F.R.MS. ;

Dear Sir,—After some labour I have obtained a copy of the
‘American Journal of Microscopy,’ published in this city, and noticed
in your February issue.

It is only fair to say that it is estimated at its true value by micro-
scopists here, being understood as a mere advertising circular for the
introduction of a toy microscope; to this date no second number has
appeared.

For a knowledge of its existence our Society is indebted to your
notice of it.*

Very truly yours,

Cuar.es Biaes, Cor. Sec.
Stare MicroscoricaL Society or ILLqNols.

PROCEEDINGS OF SOCIETIES.+

Royat Microscorrcat Socrery.

Kine’s Coutece, April 5, 1871.

W. Kitchen Parker, Esq., F.R.S., F.Z.S., President, in the chair.

The minutes of the last meeting were read and confirmed.

The Secretary stated in reference to the scientific evening which
it had been contemplated should be held on the 26th inst., that the
Council had been reminded that this date would be inconvenient,
inasmuch as the Linnean Society held their soirée on the same even-
ing, and it was therefore thought better to alter the date of our
meeting to the 10th of May next, and a circular notifying the same
would be forwarded to each Fellow. Any Fellow who had any object
or instrument of novelty or remarkable interest to exhibit, would
oblige the Council by communicating the nature of it to the Assistant-
Secretary as early as possible before 10th May.

Referring to the omission in the Obituary Notices of the name of

* We have just received the second number of this journal. Itis for April. A
rather lame excuse is offered for the fact that no number has appeared since the
first, published in November. The present is 8vo in size, and is really no better
than the first attempt—Ep. ‘M. M. J,’

+ Secretaries of Societies will greatly oblige us by writing their reports legibly
—especially by printing the technical terms thus: H y dra—and by “ underlining ”
words, such as specific names, which must be printed in italics. They will thus
secure accuracy and enhance the value of their proceedings.—Ep. ‘ M. M. J.’

238 PROCEEDINGS OF SOCIETIES.

the late Mr. Thomas Ross, the Secretary stated that the officers of the
Society were in no way to blame, or wanting in respect for the memory
of that gentleman. It was by the request of his widow to the Editor
that no such notice appeared in the Journal.

The list of donations to the cabinet and library was read, and a
vote of thanks given to the respective donors.

The Secretary announced that the Society was indebted to the
good offices cf Mr. Ladd for a very handsome present from Sir John
Sebright, consisting of an Amici microscope and apparatus constructed

by Chevalier, of Paris. Along with the microscope was an autograph ~

letter of Amici, with a long description of the instrument in Italian.
The instrument would be exhibited ‘at the forthcoming scientific
meeting.

A special vote of thanks was passed to Sir John Sebright and Mr.
Ladd.

It was also stated that, through Mr. McIntire, Mr. C. Maplestone,
of Victoria, had presented the Society with thirty-six slides of palates
of the Victorian Mollusca.

The following letter was then read from the Microscopical Society
of the State of New York :—

“ AveRICAN Microscopical Society oF THE City or New York,
64, Mapison AVENUE, Feb. 17, 1871.

“ My pEAR S1r,—It becomes my duty to inform you that at a recent
meeting of the American Microscopical Society the following resolu-
tion was unanimously passed :—

“ Resolved, that the American Microscopical Society have learned
with pain of the death of the Rev. J. B. Reade, President of the
Royal Microscopical Society of London; and feeling the great loss
that microscopical science has sustained by his death, they offer to
their fellow-workers in England their sincere regrets and sympathy.

“Yours very truly,

“8S. G. Perry, Cor. Sec.

“To THE PRESIDENT OF THE Roya Mic. Society,
Lonpon, ENGLAND.”

The President announced that Dr. Harkness, of California, was
present as a visitor.

The President then read a paper “On the Mode of Working-out
the Morphology of the Skull.”

Mr. C. Brooke proposed a vote of thanks to the President for his
communication.

Dr. Lawson: It was impossible to make any observations on the
extremely valuable paper just read by the President. It had laid
before the Fellows the results of years of toil, and when he (Dr. Law-
son) remembered, in the days when he was a student, how the views
of Owen, Melville, and many others who had gone into the cranial
theory had been presented to him, he was astonished to see Mr. Parker

PROCEEDINGS OF SOCIETIES. 239

coming forward with new views, based upon the most elaborate re-
searches. And concerning such views, he felt that he could do just
then little more than admire them, and sit down and follow them out,
and be content therewith. He considered, as he had said, that it was
a most valuable paper which had been read to the meeting, and he was
astounded at the immense amount of painstaking research which it dis-
layed.

: "The President inquired whether any Fellow could inform him which
was the best reagent to use in the researches he was making. He
had been made acquainted with the value of chromic acid by Mr.
Power, of St. Bartholomew’s Hospital; but he thought that there were
some who used now a solution of bichromate of potash with some-
thing else in it, and which, while it produced the same effect as
chromic acid, did not render the objects with which they were dealing
so brittle as that substance.

Mr. Stevenson suggested that the complement to the solution
mentioned by the President was sulphate of soda.

Mr. Slack said, that though he could not pretend to discuss the
merits of the President’s paper on the grounds of comparative anatomy,
he wished to make a remark on the allusion made by the President as
to the importance of uniting the teleological idea with the morpho-
logical, He had paid a good deal of attention to the controversies
arising out of that mode of viewing natural objects, and had been
strongly impressed with the truth of the statement that there was
really no contradiction between the distinct recognition of teleology
and that method of science which traced morphological changes from
their lowest to their highest types. It was often found that the two
schools were in deadly hostility to each other; but tracing, according
to the modern principle of morphology, the various steps in the
development of an organ did not preclude the belief that such organ
was designed for particular use.

The President said that in working out a subject morphologically,
the morphological and teleological ideas should be kept perfectly dis-
tinct, but the inquirer should be able to give a purely morphological
reason for the results obtained, for if he were a true morphologist he
had no right to come in with teleology whatever., It would be seen
in the order of nature why certain subdivisions had taken place. A
remark in reference to the lower part of the cartilage on which the
tongue of the sturgeon hung would illustrate this. The sturgeon did
not subdivide its hyoid arch in the same manner as osseous fishes, but
the subdivisions take place much higher up. He had repeatedly said
that the lower portion of the arch was the “ symplectic,” to which Prof.
Huxley had demurred, and his objection had proved to be valid;
for when he (the President) had weighed and worked out that sub-
division of the hyoid arch in the sturgeon, he had ultimately come by
anticipation to that peculiar subdivision of the second post-oral arch
which takes place in the frog to form the incus. Here was an ex-
planation of certain morphological changes without going to teleology
at all.

240 PROCEEDINGS OF SOCIETIES.

Mr. Slack handed in, and described briefly, the contents of a paper
he had written “ On the Optical Appearances of Cut Lines on Glass.”

A paper by Mr. Chas, Cubitt, C.E., was then read, “On Linear
Projection considered in its Application to the Delineation of Objects
under the Microscope.”

Mr. Hogg said the Society was much indebted to Mr. Cubitt for
bringing before them the subject of his paper. It was hardly necessary
to say that to pursue the subject as he (Mr. Cubitt) had pursued it, re-
quired the special training of his profession to carry it on successfully.
His labours would certainly tend to correct the imperfect drawings of
objects such as he had represented, and which imperfection he (Mr.
Hogg) considered to be due in a measure to the objects being viewed
under compressoriums. It was nevertheless almost impossible to
make accurate drawings of living objects unless the movements of the
animal were somewhat restricted. He might refer to the drawings made
by Mr. Topping of the fly’s tongue, and to the representations of many
other objects as an illustration of the effects of compression. So far as
his experience had gone, he had always been unable to use the camera
lucida for drawing microscopic objects; and having had no training,
such as Mr. Cubitt had enjoyed in mathematical drawing, the repre-
sentations he had made he knew to be often imperfect. He had
also found, after repeated trials, that the ingenious instrument devised
by Mr. Cooke for making better drawings of living objects was of
very little use to him. He thought Mr. Cubitt would admit that not
only in the case of Melicerta ringens, but also of Cicistes, the disk of
these very interesting animals, consisting of a hollow sarcode or pro-
toplasmic structure, which was constantly undergoing changes of form,
made the work of drawing them very difficult, and accounted for some
of the inaccuracies of published drawings.

Mr. Slack said, with reference to the observation as to the change
of form which living objects displayed, if the creature, viewed under
the microscope, altered its dimensions, the fact should be mentioned,
and a front view or side view should be given on the principles of
perspective.

A vote of thanks was then given to Mr. Cubitt.

It was announced that at the next meeting a paper would be read
from Dr. Maddox, “On the Structure of Lepidopterous Scales, as
bearing on the Structure of Lepidocyrtus curvicollis;” and also a
paper by Mr. B. T. Lowne, “On the Foot of Dytiscus.”

The Secretaries announced that some persons had been making
use of the late collector’s card and name for the purpose of obtaining
subscriptions from the Fellows. The act was wholly unauthorized.
The only persons appointed to receive money on behalf of the Society
were Mr. Reeves, and the Treasurer (Mr. Mestayer); and their
receipts alone were valid. This statement was not made for the pur-
pose of casting any reflection whatever upon Mr. Low, as the Secre-
taries did not believe that he would in any way give his consent to
such a proceeding as that which had been referred to.

The meeting was then adjourned to the 3rd May next.

PROCEEDINGS OF SOCIETIES. 241

Donations to the Library and Cabinet from March Ist to April
5th, 1871 :—

From
Land and Water. Weekly Rol ot no) Sthioe None Mra wee aare:
Society of Arts Journal. Weekly .. .. «.. «. .. Society.
Nature. Weekly .. .. SMa. cae eras Editor.
Athenzum. Weekly .. . W. W. BR.

Journal of the London Institution, No.4... .. .. .. Lnstitution.
Popular Science Review, No. 39 ae divch delist) Asep eBdtiors
Thirty-six Slides of Palates of Victorian Mollusca,
collected and presented by C. Maplestone, Esq., of
Williamstown, Australia. Mounted by S. J.
Melntine.: S200 ANG ea) Gao ea OCs 2 AC Maplestone,: Bish:
A Microscope and quantity of Apparatus. By M. Che-
vellien, OP LeME 5 ea Ae) bq Ao a0 Ge Sir John Sebright.

Francis Alfred Bedwell, M.A., Cantab., was elected a Fellow of
the Society.
Water W. REEVES,
Assist.-Secretary.

Briguron anp Sussex Naturan History Socrmry.

February 9th. Ordinary Meeting. Mr. F. Merrifield, President,
in the chair—The Secretary of the Eastbourne Natural History
Society (the Rev. A. K. Cherrill), and Mr. T. Curties, of 244, High
Holborn, London, were elected Honorary Members.

Mr. Wonfor announced the receipt, from the Secretary of the East-
bourne Natural History Society, of copies of papers read at the last
two meetings of that Society. The thanks of the Society were passed
for the donation.

Mr. T. Hennah exhibited photographs of parallel cylindrical glass
rods, rotated over similar parallel rods, to illustrate the effects of
illumination. The results were very curious, some exactly resembling
the hemispherical markings ascribed to some diatoms, and the “note
of admiration ” marks of the Podura scale.

Mr. C. Smith then read a paper “On Lichens,” in which their nature,
the differences between them and Alga@ on the one hand, and Fungi
on the other; their mode of development, component parts, mode of
propagation, their uses and applications, habitats, and other interesting
points, were well described; and illustrated by a large collection of
specimens, drawings, and microscopic preparations.

A vote of thanks was given to Mr. Smith for his paper.

Mr. H. Goss exhibited a series of British moths whose larve feed
on different species of lichens, which many of them resemble in colour
and markings.

February 23rd. Microscopical Meeting. Mr. T. Hennah, Vice-
President, in the chair.—Mr. R. Glaisyer announced the receipt for
the cabinet of two slides from Mr. Wonfor; and eighteen slides of
vegetable hairs and six illusion photographs, to which reference was
made at the last meeting, from Mr. Hennah.

242 PROCEEDINGS OF SOCIETIES.

Mr. Hennah, alluding to these photographs of parallel cylindrical
rods rotating over other parallel rods, remarked they were intended
to show how careful we must be in referring markings to the objects
themselves, and not to the mode of illumination, which he believed
was the case with some of the markings and “ spectral” dots seen and
described by Dr. Pigott.

Mr. Wonfor exhibited Beck’s illusive photographs of a small
tumbler partly covered with hemispheres, and which appeared, according
to the way in which the light fell on them, either hemispherical eleva-
tions or hexagonal depressions. In illustration of Mr. Hennah’s
remarks, he would exhibit a slide in which the fibres in plants crossing
each other, produced the illusion of hemispherical dots.

Mr. Hennah, inquiring whether any gentleman had any special
object to exhibit, said he had brought down some slides prepared by
Dr. Addison to illustrate the absorption vessels in plants referred to
by Herbert Spencer in the Linnean Society’s ‘ Transactions, and
eighteen slides of vegetable hairs prepared from specimens supplied to
him by Mr. D’Alquen.

Mr. C. Smith said he had brought slides of alge and lichens to
illustrate the moniliform gonidiac layer, common to some species of
both lichens and alge, and to which he had referred in his paper
* On Lichens.”

Mr. Wonfor then called attention to a method of preparing coal
sections described in the last number of the ‘ Quekett Club Journal,’
and said he was prepared to show vegetable scales and hairs and
fibro-cellular tissue from different species of Oncidium, Arides, Pleuro-
thallus, &e.

The meeting then became a conversazione, when, in addition to the
objects mentioned above, Mr. Glaisyer exhibited raphides in American
aloes, and cuticle of pea in situ. Mr. R. Glaisyer exhibited fern scale
and sections of coal showing woody tissues.

Mr. Hennah showed a ready manner of making a cell for dry
objects with a brass ring and electric cement.

It was determined that the next Microscopical Meeting, March
28rd, would be on “ Spores.”

March 9th.—Mr. F. Merrifield, President, in the chair.

Messrs. Marshall Hall and T. Francis, jun., were elected ordinary
members.

Mr. Wonfor announced the receipt of the January number of the
‘Quekett Club Journal’ from the Secretary, and of eight reprints of
papers on microscopical subjects by Dr. G. C. Wallich, from the
author.

Votes of thanks were given to the donors.

The President then read a paper “On Tree Planting in Brighton—
Suggested Improvements,” in which, after disproving the oft-made
assertion that trees would not grow at Brighton, he called attention
to many trees and shrubs other than those which had been already
tried which might be got to grow to the manifest improvement of the
town.

In concluding his paper, he said there was something in the cul-

PROCEEDINGS OF SOCIETIES. 243

ture of the beautiful, whether in nature or art, which tended to soften
the asperities of life and render it more tolerable to those with whom
it was a continuous round of toil. The local authorities would de-
serve well of the town if they enabled those who were confined to a
region of smoke and of bricks and mortar, to taste, in the course of
their daily avocations, some of those refreshing and pure delights
which lead those more happily circumstanced to yearn with an in-
describable longing for the “ greenwood,” and to lavish on the enjoy-
ments of a country residence the hard earnings of the counter or the
desk—such delights as the bursting of the leaves and flowers in spring,
the sunlight shining through the green luxuriant foliage of summer,
or the glorious hues of the woods in autumn, and even the graceful
sweep of branches silvered with the frosts of winter.

March 23rd.—Microscopical Meeting. Dr. Dawson in the chair.

Mr. R. Glaisyer announced the receipt of five slides of starches
for the cabinet from Mr. Wonfor.

Dr. Dawson, in introducing his subject for the evening —“ Spores”
—said he considered the spore of a fern was really a seed, and wished
the members to pay a little attention to the determining a point not
yet sufficiently made out, viz. “What a spore really was?” If this
were settled it would materially help in unravelling the assumed
extraordinary generation of ferns, as held by some authorities.

A seed contained all that was necessary for the development of the
future plant, except air and water. With this idea, he boiled powdered
asbestos in fuming nitric acid and then washed it carefully with dis-
tilled water until all trace of acid was removed. In this he planted
mustard seed, which was excluded from the surrounding air by placing ,
it in a closed glass vessel. The seed, it would be observed, had grown
and produced cotyledons, from what he called the innate power of
growth.

The size of a seed was immaterial; for, however small, it con-
tained within itself material to sustain the plant until it could derive
nutriment by the root and plumule. He believed the same held true
of the spore, and that it was this active innate principle which gave
rise to the prothallus.

As from the axis of the cotyledons the plant grows, so always from
one point on the prothallus the fern grows. It would, therefore, be
seen that the great point to be determined was the relative position of
the spore to the seed. The spore, he conceived, had sufficient innate
power to start a prothallus, from which, when formed, the future plant
grew, and not by a generation on the surface of the prothallus.

Mr. C. Smith considered the spore simply a cell containing plasma,
which formed a chain of cells, from which sprang the future plant.

Mr. Wonfor thought the accepted generation of ferns so contrary
to everything else in nature, that it required more than the mere
authority of names to be believed, because, by this theory, the sexual
organs were described as being developed in the earliest, and not,
as in the rest of nature, in the highest state of the individual.

Dr. Dawson wished the members to grow and observe fern spores

244 BIBLIOGRAPHY.

during the next few weeks, and intimated that he would read a paper
in May “On the Fern Spore and Seed Compared.”

The meeting then became a conversazione, at which

Mr. Smith exhibited Ephemerum serratum, with prothallus and
germinating spores of Pteris serrulata and Funaria twelve and twenty-
one days old.

Mr. Ardley exhibited spores of ferns and elaters of Equisetum.

Mr. Davies exhibited specimens of the rare lichen—Collema derma-
tinum, which appears to be a form of C. fervum; a fertile specimen of
the little-understood Collema ceranoides, from West’ Sussex; Lepto-
gium Schraderi, from Woolstonbury Hill; and a fertile Brywm Donia-
num, from near Chichester. This latter plant is seldom found fertile
in this country. It is common in Italy, and appears to wander along
the shores of the Atlantic, always being found near the coast.

Mr. Wonfor exhibited spores of leaf fungi, ferns and seaweed,
spores and elaters of Equisetum and Marchantia, prothallus of fern,
and the potato fungus.

It was resolved that the subject for the April Microscopical Meet-
ing should be “ Vegetable Cells.”

BIBLIOGRAPHY.

Sitzungs-Berichte der naturwissenschaftlichen Gesellschaft Isis in
Dresden, Herausgegeben von Carl Bley. Jahrgang, 1870. No. 4—6.
- Dresden. Schépff.

Die chemisch mikrokopische Untersuchung d. Harns. auf Seine
wichtigsten Krankhaften Verdinderungen. Von Dr. O. Puhlmann.
Berlin. Hirschwald.

Abhandlungen der Konig]. Akademie der Wissenschaften zu Berlin.
Aus. d. J. 1869. Berlin. Dumler.

Untersuchungen iitber Blasenbildung und Epithelregeneration
an der Schwimmhaut d. Frosches. Von Prof. Biesiadecki. Wien.
Gerolds Sohn.

Beitrage zur Kenntniss der Gattung. Najas. L. Botanissche In-
augural-Dissertation. Von P. Magnus. Berlin. Calvary.

Bryozoi fossili italiani. 4 contribuzioni. Dr. A. Manzoni.
Wien. Gerolds Sohn.

The Beginning, its When and its How. By Mungo Ponton,
F.R.S.E. London. Longmans.

The Mystery-of Life. An essay in reply to Dr. Gull’s attack on
the theory of vitality in his Harveian Oration for 1870. By Lionel
S. Beale, M.B., F.R.S. London. Churchill.

i
)

Journal, Faun

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icroscopica!

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Way

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Lepidoptera Seales § fragments.

THE

MONTHLY MICROSCOPICAL JOURNAL.

JUNE 1, 1871.

I.—Additional Observations concerning the Podura Scale.
By Dr. J. J. Woopwarp, U.S. Army.
(Read before the Roya Microscopicau Society, May 3, 1871.)

Frsruary 7th, 1871, I had the honour to forward to the Royal
Microscopical Society a paper “On the Structure of the Podura
Scale, and certain other Test-objects, and of their representation by
Photo-micrography.” This paper was accompanied by a number of
photo-micrographs, one of which (No. X.) was not as satisfactory, in
the paper prints, as I could have wished. Subsequent experience
has increased my confidence in the opinions expressed in that paper
with regard to the scales of the test Podura (Lepidocyrtus eurvi-
collis), and a fortunate circumstance has given me the opportunity
of representing these views in a more convincing manner.

Shortly after my paper had been forwarded, I received a visit
from Mr. Joseph Beck, who is spending a few months in the United
States. Mr. Beck had with him an excellent microscope, the work-
manship of the well-known firm of which he is a member, and a
number of fine high-power objectives by the same house. With
these objectives he exhibited to me several slides of the scales of the
Lepidocyrtus curvicollis, collected by himself from carefully-identi-
fied insects. He aimed at the exhibition of the exclamation marks
as such, using a right-angled prism, achromatic condenser, and
small coal-oil lamp. Before leaving Washington he was so good as
to give me one of these slides, indicating on it a scale which appeared
particularly adapted to the display of the exclamation marks.

Certainly this scale, which was yoth of an inch in length, and
zooth of an inch broad at its widest portion, surpassed in the dis-
tinctness of its markings any of the scales of this species which have
~ hitherto come into my possession. With central monochromatic
light, the immersion y'sth, and amplifier, I obtained a negative
showing the exclamation marks better than any representation of
the kind I have yet been able to obtain. I send herewith a paper
print. The magnifying power is 3200 diameters.

But immediately afterwards, with the same optical combination

VOL. V. T

246 Transactions of the

and magnifying power, without any change in the cover correction,
by simply rendering the illuminating pencil oblique, and slightly
withdrawing the objective from its first focal position, I obtained a
negative which displays the “bead-like” or varicose appearance of
the ribbing more satisfactorily than I had previously been able to
do. A print of this negative is also forwarded herewith, and I beg
that the two may be compared with each other and with those sent
with the former paper.

I must add that, since writing the foregoing remarks, I have
received from Mr. 8. J. McIntire a very interesting letter, in which
he explains to me that I was in error in designating the specimen
of Degeeria described in my recent paper as Degeeria Nigro-macu-
lata. It seems it is really the Degeeria or Seira domestica. I was
misled by Mr. McIntire’s label on the slide, which I supposed to be
correct. I have never seen either of the insects. This inadvert-
ence, however, does not affect the question of structure.

Royal Microscopical Society. 247

I1.—Remarks on the General and Particular Construction of the
Scales of some of the Lepidoptera, as bearing on the Structure
of the “ Test Scale” of Lepidocyrtus curvicollis. By BR. L.
Mappox, M.D.
(Read before the Royau Microscorican Society, May 3, 1871.)
TE investigation of the intimate structure of some minute objects
with which the microscopist is quite familiar, whether for the pur-
pose of demonstrating their integral beauty and exquisite design, or
for exhibiting and testing the optician’s skill, is a source so replete
with difficulty, that the opinions of trustworthy observers are pre-

EXPLANATION OF PLATES LXXXVI., LXXXVIL, anp LXXXVIII.
Lepidoptera Scales and Fragments.

Fic. 1.—Part of a China butterfly seale—Tanonia Cnone, Ind. China—showing
the outer transparent membrane : to the left, a beaded appearance of
the framework, out of focus; to the right, various chromatic effects in-
duced by change of focus and direction of the incident light. x 1600.

2.—The same portion of the scale, showing the structural framework of the
ribs and transverse bars, x 1600.

8.—Part of the same scale seen reversed, indicating on the ribs what is
believed to be the vertical attachments to the outer or middle mem-
brane when three exist, x 1600.

4.—Part of another scale of the same insect, showing the outer membrane
and the framework with chromatic interference and pseudo-beading,
x 1600.

5.—Part of a large yellowish-white scale from a China butterfly wing—
Papilio Erithonius (Cram.), Ind, China, At one side is seen the violent
chromatic effect of interference caused by the longitudinal ribs and
oblique attachments—“ strize”; also the markings of the transverse
bars on the (middle or?) outer membrane, for it appears to consist of
two layers. x 1000.

6.—An injured dark scale from P. Lrithonius (Cram.), Ind, China, with
a portion of the inner pigmentary membrane turned over, and the
middle showing the vertical attachments of the ribs, and the outer
membrane, X 1000.

7.—An injured dull-grey scale from the same butterfly, indicating the inner
ribbed membrane with its pale, granular, pigmentary deposit, and
the oblique framing of the middle or outer layer (“‘striee”), x 1000.

8.—Irregular fragments of the external pigmentary deposit from a dark scale
of P. Erithonius, x 1000.

9.—Part of a scale from the wing of the same butterfly as Fig. 1, showing
three membranes—the outer, the middle retaining a part of the frame-
work, and the inner with the heavier portion: also two fragments ;
outer membrane, a; ribs, b. x 950.

10.—Fragment of a foreign butterfly scale, received from Mr, McIntire (upper
surface of wing and scale), showing the membrane and delicate frame-
work, with indications of a beaded appearance due to thickening at the
junctions of the bars and ribs, x 1600.

11.—Fragment of a scale from the same insect, showing a marked pseudo-
beaded appearance in the ribs. The scale is remarkably free of pig-
ment. % 1600.

12.—Part of a scale from the same butterfly (under surface of wing, upper
surface of scale). The transverse bars are rare, except at the edge;
the longitudinal ribs, which show the supposed vertical attachments
atone or both sides of several, producing when in place the pseudo-
beaded appearance, well seen in the rib, x 1600. (Fie. 13.

12

”

248 Transactions of the

ferred rather than undertake the examination for ourselves ; or else
we are disposed to rest satisfied with their general aspects.
Occasionally, however, startled by something overlooked, or by
new and imposing views, there is risk of being carried away by
the stream of novelty while waiting for extended evidence. Hence

Fic. 13.—Fragment of a scale of an Indian butterfly—Terias Hecuba, Ind. China—
slightly charred, showing the outer framework and membrane, x 1600.

14,—Beaded chromatic appearance of part of Fig. 17, well charred, x 1600.

15.—Part of the same scale as Fig. 18, showing the longitudinal ribs, the
transverse bars and the oblique attachments, which give rise to the
marked wavy “Test scale” aspect. This figure has been roughly
enlarged for showing artificially the production of beads by inter-
ference.— Vide photographs. x 1600.

16.—The direction of the incident light altered, the scale now furnishing the
pseudo-beaded appearance at the junctions and interspaces, x 1600.

17.—A torrefied scale from the body of the same insect, 7. Hecuba, showing 2
marked resemblance to some of the scales of Lepidocyrtus curvicollis,
x 500. ;

,, 18.—A long scale from the body of the same butterfly, well charred, showing

the “notes” and transverse bars (‘‘strie”) simulating the “Test
scale,” x 500.

» 19.—A body scale from the same insect still more torrefied, throwing the
longitudinal ribs into somewhat irregular lines, very much resembling
Mr. McIntire’s figure, Dr. Woodward’s and my own photographs of
Degeeria domestica (Seira domestica, Lubbock), x 500.

» 20.—A scale highly iridescent and of some substance from near the shoulder
of the wing of the large China moth (? Attacus cynthia), x 230.

,, 21.—A portion of the same scale, showing pseudo-beads in the longitudinal

ribs and interspaces, x 1000.

22—From the same scale near the tip, showing the framework and mem-
branes, X 1000.

23.—A fragment from a similar scale of the large China moth producing two
sets of pseudo-beads, one on either side of the long rib, with a dark
shadow on one side, x 1000.

24.—The same portion of the scale as Fig. 23, showing the framework of longi-
tudinal ribs and transverse bars, x 1000.

» 25.—A fragment of a scale from the wing of the same moth, showing the
inner membrane and pigmentary deposit, the transverse bars (“‘strize”’)
and (middle or) outer membrane with a portion of the oblique at-
tachments, x 2625.

ay some scales the pigment layer apparently covered the transverse
bars.

» 26,—A coarse scale of Lepidocyrtus curvicollis, seen under different aspects.

a, The under surface, first ocus, showing the longitudinal ribs somewhat
bent and depressed, marked faintly with transverse markings.

b, The same focussed rather more deeply, producing the beaded
appearance of the rib.

c, The same part, the focus carried a little deeper, giving rise to
apparently elongated depressions, with the shadows on the same
side as in a.

d, The same portion under a still deeper focus, producing a dark,
cellular arrangement with bright edges.

The illumination remained unchanged in these four figures.

e, The scale, incident light and focus altered from a, }, c, d, pro-
ducing the bent, short, clumsy, pin appearance, slightly marked,
and with a greenish shadow on one side, resting apparently on a
dark-grey membrane, the points of the pins shading off obliquely.
(Vide Pl. XXXVII., Fig. 5, of Mr. MeIntire’s Templetonia
nitida, ‘M. M. J.’) :

”

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Royal Microscopical Society. 249

caution is especially necessary ere embracing new opinions on the
structure of minute more or less transparent bodies, however refined
may have been the method of investigation, if they be not fully sup-
ported by analogy in objects of the same nature, which permit of
more easy examination, and certainly it becomes imperative when
fresh research tends to opposite conclusions.

By these preliminary remarks it is not intended to convey
the idea anyone should remain satisfied with the knowledge already
gained, but simply not to be too ready to accept evidence on a scanty
basis which for various reasons is open to considerable doubt.

All acknowledge the manifold difficulties that supervene on at-
tempting to decide the structural nature of minute transparent
objects, when they are replete with optical effects, resulting from the
transmission of light, at varying angles, through irregular surfaces

f, The focus, only, altered, giving rise to dark, elongated areas—
“notes,” supported on a pale membrane marked transversely ;
the heads not rounded, but somewhat acute at one corner, very
like the appearance figured in *‘ Quekett on the Microscope,’
plate viii., fig. 4,a; and some of the notes in Dr. Woodward’s
photographs just received.

g, The position of the scale and incident light altered ; an appearance
approaching the first focus, but with two dark shadows, inter-
rupted, either side of the long rib; the transverse markings
still seen.

i, The scale and direction of the light slightly changed, furnishing
dark shadows and highly chromatic effects (seen in the coloured
drawing), with universal faint striation.

h, The appearance of a framework similar to the Lepidoptera scales,
seen with difficulty, and when the light is not thrown sufficiently
obliquely to produce colour—all magnified 2625 diam.

The central portion of the figure gives the optician’s view,
but showing oblique lines faintly.

[The remaining figures refer to some exquisite photographs and
figures which have been placed by Dr. Maddox in the Society’s
Collection.—Ed. ‘M. M. J.’|

Fic. 27.—A photograph of interference image of Fig. 31, produced by artificial
means; simulating beads.

28.—A photograph of the same artificial construction, using + plate lenses;
simulating Degeeria domestica scale.

29.—A photograph furnishing bright beaded spots, dark shadow and coales’
cence of the ribs.

30.—A photograph showing faintly to the left (very distinctly in the negative)
a chain of dots (? beads) and the general image as a composed or
intermediate one between Figs. 28 and 29.

» 31.—The rough pencil sketch of Fig. 15, used to construct the artificial framing,

»» 32.—Pencil sketch of injured scale of Humming-bird Sphinx (recent).

’ a, The edge bars are rubbed into wavy lines.
b, The external coat removed.
c, The little round particles of which the coat consists are rubbed
into a confused mass.
d, The surface seen in its natural state; the round particles are most
clearly seen on the bars, but they entirely cover the surface.
e, The quill is seen as a hollow tube.

(Fig. and description by Dr. A. Southby, Italy.)

”

”?

”

@e

250 Transactions of the

of different thicknesses and refractive powers, or internally stopped,
reflected or dispersed. The more the structure retains this charac-
teristic, the greater the difficulty to traverse with confidence the
shoals of conjecture.

In venturing to bring before the notice of the Fellows of the
Royal Microscopical Society, the subject of the general and particu-
lar construction of some of the scales of the Lepidoptera, after the
recent and valuable contributions by Mr. McIntire, Mr. Jos. Beck,
Mr. Wenham, and Dr. Woodward, as well as the very interesting
article by one of your secretaries, Mr. Slack, contributed to the
pages of ‘The Student, No. 1, February, 1870, some apology is
necessary ; but the minute construction of the scales of the Lepi-
doptera being, so far as I can judge, still open to inquiry, and the
subject so full of interest in reference to the views advanced by Dr.
Pigott, &c., let me ask your indulgence to be permitted to lay before
you the results of a careful, if not very extended, examination, ac-
companied by coloured drawings of such portions as touch upon the
question of beads or beaded structure, as well as the general ar-
rangement of parts in relation to the same, in the “ Test scale” of
Lepidocyrtus. .

If these researches have led me to differ from some authorities
in various particulars, the results are stated with diffidence, and
with the desire further observations may be undertaken by those far
more able than myself to compass the inquiry; but if the evidence
can, in any way, tend to place the subject in a more satisfactory con-
dition, or increase the testimony of others, it will amply repay for
the trouble and time it has taken. Mr. Slack in the before-mentioned
pages of ‘The Student’ has furnished the opinions of many observers:
not to lengthen unnecessarily this article, I shall allude but briefly
to them in passing, and refer to his pages for particulars.

The announcement made by Dr. Pigott, in the pages of the
Society’s Journal for December, 1869, on the structure of the Podura
scale, “Test scale,” Lepidocyrtus cwrvicollis,* took many of us by
surprise—and naturally so, considering this scale to have for years
been so continually under observation, and the special study of
that accurate observer and artist, the late Richard beck ; therefore
to him our thanks are due for rousing us from our wonted apathy,
and for pointing out fresh methods for obtaining increased magnifi-
cation, claiming some advantages over high-power objectives and deep
eye-pleces.

To such a contrivance he has given the name “ Aplanatic .
Searcher,” and by its means has obtained results which abound with
interest ; though, to the minds of many observers, they are received
with considerable doubt, or referred to optical effects of an illusory
nature.

* Vide p. 300.

Lepidoptera Scales & fragments.

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el ek oh oe OS GN Sa a

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Royal Microscopical Society. 251

Unfortunately, the information regarding the structure of the
optical part of the instrument is of such a conservative character,
both in the original paper, published in the ‘ Philosophical Trans-
actions, and in the ‘Journal of the Royal Microscopical Society,
that it does not furnish data sufficient for its perfect construction ;
and as it appears to have resulted from “error and trial” rather
than from computation, hence one reason why others may not be as
successful as he appears to have been. I can well understand the
tediousness of the research and the patience necessitated to bring
such a method to so successful a phase, without losing defini-
tion. Doubtless it will stimulate both opticians and amateurs to
renewed efforts to cover the “ residuary aberration”; but if we do
not also get rid of the secondary spectrum, there is something more
to be achieved than is yet accomplished. Possibly some refracting
cement, as Mr. Grove’s purified resin and castor-oil, or Canada
balsam and castor-oil, if made one of the components of an achro-
matic ‘‘ concave” or “corrector,” may furnish some help.

By no means do I wish to detract from the advantages of the
“aplanatic searcher” in other hands, but in mine it did not fulfil
the expectations entertained. It certainly furnished great facility
for bringing out colour in lined objects of different refractive power,
and thus perhaps it may have a wide claim to our fayour, provided
we are not carried away by the influence, by reason, as Mr. McIntire
so aptly expresses it in his note of Jan. 20, which I take the liberty
to quote, that “the colour invests some objects with a new charm.”
It was not found to increase the defining power of the objective, but
this may have been due to want of ability on my part.

It seemed questionable whether three “ over-corrected ” bodies,
compound lenses, eye-pieces, searcher, and objective,* and the addi-
tional over-correction furnished by the thin covering glass, would
provide, by one traversing between the two others, perfect achro-
matism.

It may perhaps be as well to point out the error in the original
paper, ‘ Phil. Trans.,’ and the appended note in p. 129, where, in the
definition of the aberrations, positive and negative aberration have
been confounded. The same error is repeated in the present
‘Quart. Journal of Micros. Science,’ evidently having escaped the
notice of the author.

Whatever may be its value as regards depth of focus, &c., of this
I feel confident, that at the same time that it furnishes a very ready
means for increased amplification, so it also facilitates optical errors
in observations. The limitation as relates to light, the length of
tube needed, though inconvenient, are quite, if not more than,
balanced by the erect image and the use of low powers and eye-

* Vide editorial remarks on Dr. Pigott’s paper in the ‘ Phil. Trans.,’ in the
‘M. M. J,’ No. XXVIL., p.. 129.

252 Transactions of the

pieces instead of high ones. The depth of focus, in many ways, is
very valuable, yet when oblique light is employed, and the object
develops colour, is a constant source of danger to correct interpre-
tation of structure. This, it is believed, will be acknowledged by
those accustomed to examine objects structurally.

When more is learnt of its optical combinations, or some secure
method discovered for furnishing a combination as “ corrector” and
“amplifier,” we shall all feel deeply thankful to Dr. Pigott that the
employment, long since adopted and rejected by opticians, of inter-
vening lenses, has found a permanent place in the addenda to the
ordinary instrument.

The object of this paper being to deal with the general and par-
ticular structure of Lepidoptera scales, and their relationship to the
structure of the “ Test scale,” the “aplanatic searcher” would not
have been alluded to, had not some of the observations and draw-
ings been made with the form found by “ error and trial” conve-
nient, viz. a triple and double achromatic, adapted to the proper
searcher, racked tube, and employed with a Gundlach’s immersion
No. 7* (7eth), Wales’ 4th, and Smith and Beck's jth, with a No. 1
eye-piece and the equilateral prism, proposed by your much-
esteemed late President, used with a bright north daylight, without
achromatic condenser, except for the central portion of the Fig. 26
—the object being to simplify as much as possible the mode of
observation. :

All extraneous light was shut off from the object by a limiting
aperture in a thin brass slide, on which the objects between two
thin covers, for reversal, were fixed by springs attached to the sup-
port; or if the object were on one of the ordinary slides, it was
surrounded by an opaque ring or slit, besides other precautions
alluded to farther on. :

After describing the general appearance with low powers, the
waviness of the scale according to the illumination giving place to
“yibbing, shaded very darkly,” &c., Dr. Pigott states,* “ with 1200
these ribs have divided themselves into a string of longitudinal
beads. But with 2300 they appear to lie in the same plane, and
terminate abruptly on the basic membrane. Upon focussing for the
strings of beads attached to the lower side, the beading appears in
the intercostal spaces.” Also, with “more oblique, yet achromatic”
illumination, “the intervening spaces showing fine traces of inter-
secting lines.”

Now, if these remarks be understood correctly, the structure of
the “Test scale” would be as if composed of a (flat) membrane
having on each side rows of beads external to its surfaces; rows of
beads longitudinal on the one surface and oblique on the other.
Again, “synthetically,” the same observer finds proofs of his views

* P. 300, No. XIL, 1869.

Royal Microscopical Society. 253
in the “finest and most transparent scales of ‘azure blue,” hence
we must consider, whatever be the true structure of the “Test
scale,” the Lepidoptera scale is of the same nature. This admitted,
it becomes easy to show that the Lepidoptera scale, though furnish-
ing more or less all the optical appearances of the “ Test scale,” is
in reality not constructed after this method. ‘Thus a doubt is at
once raised as to the correctness of the view entertaimed of the
structure of the scale of Lepidocyrtus ewrvicollis, and its congeners.

Before touching the microscopical investigation of the Lepidop-
tera scale, it may be as well to ask if we have in any dermic struc-
ture of the animal series one composed of beads lying either side of
a basic membrane? I know of none, though of course it does not
follow such may not exist ; therefore these remarks are open to cor-
rection. But what possibly is the function of so elaborate a struc-
ture as found in the scales of the Lepidoptera and Thysanuradeze
generally ?

Surely little can be founded on such a beaded structure, whether
for strength in the arrangements, or function, beyond a covering
and the power to intensify their iris hues; though if we admit that
the generally-received opinion respecting the scale of the Lepi-
doptera is more correct, as I shall show farther on, then by the
substitution of a true framework for beads, we obtain strength, and
from its position may eventually find some greater purpose to be
effected in the economy, beyond contributing to those wonderful
iridescent qualities and common tegumentary relations ; and which,
possibly, is one effecting a change in their semi-fluids by the action
of the external air through delicate investing membranes.

All recent scales that have been examined gave more or less
evidence of containing some greasy semi-solid material within the
membranes; and possibly it will be found the more the body of the
bearer partakes of this fatty nature, the more also the scales partici-
pate. Such seems to be the case in the large fatty-bodied moths.
This, doubtless, largely facilitates the resistance to wet, which in
the case of the Lepidoptera would otherwise be almost fatal to their
flight.

3 In my micro-chemical investigations of some of the common
butterfly scales, and which Mr. McIntire did me the honour to
insert as a note to his paper “On the Minute Structure of the
Scales of certain Insects,’ * it was found the contents of the scale
could be in part removed by various solvents. In addition to
those experiments, to which reference is made, strong sulphuric
and nitric acids, &c., have been tried, with the hope of obtaining
better characteristics of the internal structure; but perhaps the
most satisfactory plan has been to char the scales,—a suggestion
taken from one of my friend Mr. Wenham’s letters, to hand some

* <M. M. Journal,’ No. XXV., p. 3.

254 Transactions of the

time since, when speaking of the structure of the “Test scale,” and
to which he alludes in his remarks on that object in the ‘M. M.
Journal,’ No. XXL, p. 124, but which happy idea he had not, it
appears, then carried out, for want of the coarse scales; but I learn
from him, April 6, that he has done so since with much success.*
This will claim notice farther on.

Hitherto, with the generality of observers, I had regarded the
scales of the Lepidoptera as composed of two distinct membranes
with their longitudinal ribs (often showing a very beaded look) and
cross-bars; but in addition considered these parts, which have been
rather too vaguely defined, formed a framework of union between
themselves and the membranes, converting the interspace into more
or less minute areas, and hence fallmg towards Dr. Bowerbank’s
views, though somewhat differing from them in one or two parti-
culars. He makes them to consist of three distinct layers, viz. “ the
upper membrane, which contains the colouring matter; the striz,
which constitute the frame; the under membrane, which is nearly
colourless ; and finally, the ribs, which are in reality tubes.” Where
we are at variance will be seen when the special relations of the
parts are considered. It has been only after much trouble I could
find a solution to the many appearances, old and new (¢.e. with
aplanatic searcher), in conformity with such arrangement. It was
at last to injured, dried and charred specimens more particularly,
attention was directed. Without detailing the trouble in attempt-
ing to break up scales in particular directions—in fact, to dissect
them in various ways, and for convenience—the following remarks
will apply to scales of two common characters—though not natu-
rally divided, for some scales partake of both, viz. the simple and
the wavy scale—derived from their appearance under low powers.

The simple scale, as alluded to by others—as Quekett, De la Rue,
Dujardin, Carpenter, Beck, Gosse, Slack, McIntire, &e.—is undoubt-
edly composed of two or moremembranes. The outer, as so beau-
tifully shown by Mr. Jos. Beck’s simple experiment, on Thysanu--
radeze scales, and which he kindly made before me, and enabled me
to repeat myself, is composed of an almost structureless membrane
(Dr. Bowerbank’s under membrane?), in most scales exceedingly
thin and transparent, in others thicker and coloured (possibly
capable of being split into two layers or lamine, though I have
only met with a few examples, and these might have consisted of
three distinct membranes), occasionally marked on the inner surface.
with faint indications of attachments of the opposite surface of the
ribs and bars, or of oblique lines, “strize” of others, and sometimes
containing fine pigment granules (Fig. 9).

The inner one, as made up of a coarser and darker material,

* Now published, vide ‘M. M. Journal,’ No. XXIX., p. 216.
+ ‘M. M. Journal,’ No. XXIII, p. 253.

K

Royal Microscopical Society. - 205

with also pigmentary deposit, in the substance of which the frame-
work of the longitudinal ribs is fixed, projecting somewhat on the
free surface, and in which the minute cross-bars running between
the longitudinal ones at right angles are imbedded, projecting on
the surface of the membrane facing the opposite one—the “ trans-
verse striz” of others (Fig. 6); but besides this, the longitudinal
ribs especially, if not the crogs-bars, appear to be attached to the
opposing surface of the outer or next membrane—if three, by minute
more or less wider or narrower vertical projections or septa (Fig. 12) ;
so that the ribs are bound to each other by cross-bars, and to the
opposite membrane by short columns or attachments at very dif-
ferent points; hence, where these draw the two surfaces of the
scale so closely together, that they are virtually in contact, a de-
pression at that point occurs in the rib, giving it a lobed, if not
twisted appearance, and much increasing the difficulty to separate
the membranes from each other. Where they alternate to either
side of the long rib, giving it a furrowed figure, and the scale is
illuminated in a particular direction, the rib seems irregularly bent,
and on either side, a little to the right or left, we see the illusory
appearance of a twin row of beads, caused by the vertical parti-
tions or framing at the junctions, refracting the light at those
points more than at the adjoining ; whilst a trifling alteration made
in the direction of the illuminating pencil divides the rib itself between
those rows, and one or two sharp dark shadows start out on either
side of the rib, according to focus, and possibly caused by interference
(Figs. 23-26). The transverse bars are most likely also slightly
attached by their under surfaces to the opposing membrane where
we have indications of a beaded character under ordinary observa-
tion; at any rate, the spaces embraced between them are occasion-
ally indicated on the opposite surface under some conditions of the
incident light (Fig. 5); or they appear capable of being split
(Fig. 9).

‘In the wavy scales the same parts exist; but instead of the
vertical attachments being only close on either side of the long
rib alternately right and left, and those of the transverse bars, the
attachment takes place also obliquely across the scale, from the
quill both sides towards the centre, and maps out the interval be-
tween the ribs into rhomboidal areas or beads, according to the
illumination, and which are under other positions, &., nevertheless
seen crossed by the minute transverse bars belonging to the longi-
tudinal framing (Figs. 15, 16).

When the membranes of the scale so attached can be separated,
the lines of junction on the opposing surface of the opposite mem-
brane are easily seen in some, and give the ordinary appearance of
faint yet bright lines, or ribs, or bars, resting on that membrane,
at varying angles in relation to the length of the scale (Fig. 7);

256 Transactions of the

and where the attachment has also taken place beneath the longi-
tudinal rib, often a corresponding interval is noted, so that the
oblique markings appear to follow one another in a series of broken
lines: sometimes the lines or streaks seem to pass towards the
central rib, as though no union had taken place when crossing the
long and transverse bars, though this is rarely the case. The long
ribs have a somewhat puckered look at those oblique junctions
(Fig. 19). In many scales the strong portions of the framework
contract towards each other, or no longer continue a parallel course ;
and where the rib gets a strongly-twisted look, supposed to be due
to the vertical partitions, a strong shadow is cast on one or other
side, according to the incident light and position of the scale, the
rib itself seeming to shade off towards the oblique attachments. If
the transverse bars be continued, as it were, far into the substance
of the long rib, they give a markedly beaded arrangement.

It is here, I think, we geta clue to the construction of the “ Test
scale.” For a very fine example of this object, I am greatly indebted
to the kindness of Mr. McIntire, and from which slide the drawings
on Fig. 26 have been made, in the following order, after carefully
studying different scales.

The Lepidocyrtus scale, in the strongly-marked examples, when
first focussed upon at its inner surface with high powers, shows
according to the illumination a series of ribs as stated by the late
Richard Beck, more or less continuous in their length, with faint
cross striz, first directly pointed out, I believe, by Dr. Pigott (Fig.
26,a); the ribs seem bent somewhat to one or other side, due it is
considered to the vertical attachments, so getting depressed and
rather twisted or narrowed as they emerge on either side, towards
what is seen to be with other illumination the oblique junctions
(“strie”) to the transparent membrane, assuming an outer and inner
membrane at least to exist; while these form, as it were, a broken
or interrupted septum between them, and thus being repeated at the
opposite side of the rib, but at a higher or lower position, we get
the boundary of the opposite ends, so as to embrace the heads of
what at a little deeper focus forms an elongated, more highly re-
fracting part of the scale, in which the transverse markings, which
correspond to the transverse bars of the Lepidoptera scale, are readily
seen, and forcibly figured by Dr. Pigott (wide Fig. 26,b). The fine
transverse “striae” which appear at the first focus, I am inclined
to regard as arising from the refractions occasioned at the junctions
of the vertical septa, and where these alternate to right and. left,
they give rise, as in some examples of the Lepidoptera scale
(Fig. 23), to a doubly-beaded appearance of the rib, with a dark in-
tervening shadow, seen under another focus and direction of the
incident light, as at 2, Fig. 26.

Still deepening the focus but retaining the same illumination as in

Royal Microscopical Society. 257

a, b, the refracting portions of the ribs appear like elongated depres-
sions, c, having the shadows brought to the same side as ina. Again
deepening the focus without any other change, the elongated de-
pressed areas seem to interrupt the light in every direction, except
at their edges and oblique junctions, and thus map out the surface
into illusory dark cells with light borders, d.

Changing the position of the scale and incident light, we find
the rib more highly refracting the light at one end than the other,
furnishing the appearance of a clumsily-made bent pin, with faint
transverse markings still visible,e. The knobbed look is un-
doubtedly due, in part, to the rib being rather more elevated there
than in the other portions of its course, and corresponds to Mr.
Wenham’s figure,* which is very truthful when an oblique view can
be obtained of the scale, and to the knobbed appearance of the notes
in Dr. Woodward’s magnificent photographs ; also in Mr. McIntire’s
figure of Templetonia nitida.}

The interruption of the points of the pins seems to be chiefly
due to the depression of the rib at those parts from closer contact
with the opposite membrane, causing it also to bend a little off to
one side.

Retaining the illumination, but deepening the focus, we pro-
duce the figure f, still showing the transverse markings, the shape
closely corresponding with the figure 4a, x 1250, pl. 7, engraved
in Quekett’s work on the Microscope, second edition, where it will
be noticed the heads of the “ notes” are rather notched than rounded,
as likewise with very many of the “notes” in the beautiful recent
photographs, No. 346, new series, by Dr. Woodward, of the “ Test
scale,” x 3200, received from him the 7th of this month (April),
and to whom I feel deeply indebted for the charming picture; also
for a stereoscopic picture of the same scale, to hand somewhat later.
Although I can easily combine most stereoscopic pictures without
the use of any stereoscope, I find it difficult to converge the eyes
sufficiently to close these images perfectly, yet when obtained,
though the “notes” form somewhat elevated areas above the other
surface, they have not the appearance of solidity one would at first
sight have expected ; but this leads me still more to hold the opinion
that their production is an optical effect and not the structural ar-
rangement. The photo-micrographs are wonderful results of skill
in focussing the two different views, which scarcely depart perhaps
sufficiently from the optician’s view,— to furnish a strong stereoscopic
image of the structure. The shadows also are more on one side,
and the central light is long and narrow.

Still shifting the direction of the scale and the illuminating rays,
we produce much the appearance of the first focus, but with two

* “M. M. Journal,’ No. XXT., p. 125.
+ Ibid., No. XIIL, Plate XXXVII._

258 Transactions of the

dark shadows on either side of the bright part of the rib; these
have been noted by Dr. Pigott (g, Fig. 26). The slightest touch
of the fine adjustment or prism displaces them, and by a fair
appliance of patience, “ toying” with the focus and the adjustment
of the prism, the image is converted into the appearance at 7, when
the chromatic effects are at their highest ; as on either side we have
blue and yellow, faint purple and orange, interrupted spaces, crossed
by a fine striation, which I believe are the representatives of Dr.
Pigott’s fine set of beads, if not those brought out on the upper
surface in my photographs,* yet caused by the same internal dispo-
sition of the parts as in the Lepidoptera waved scales, and giving
rise to similar illusory effects. Still, it occurred to me if this were
the case, some such structure which is so evident in the Lepidoptera
scale as a supporting framework ought to be present. Much time
was spent in seeking this, as a friend who seeing me at work
naively said, with the head in a bag, as a black velvet covering was
so arranged as to shut off all extraneous light from the stage of the
microscope, and made to envelop the head; for without such help,
and which was constantly used in these examinations, I could not
satisfy myself of the reality of Fig. 26, h. Fearful prejudice towards
this view might influence the interpretation, after being well seen
the slide and prism were shifted, and the scale examined at another
time with similar success. If the daylight were not very bright,
the transverse markings or bars were not seen with sufficient clear-
ness to draw them with the camera lucida, which has been used for
all the figures. It is here that monochromatic light, employed
after the method of Count Castracane, would, it is deemed, be highly
advantageous.

These are some of the appearances seen under varying arrange-
ments, and have been made the subject of the Fig. 26, as they are
not generally given by others, and may help towards a better
understanding of the nature of the scale, and its similarity to the
wavy scales of the Lepidoptera. The centre portion of the Fig. 26
represents the optician’s view; and here an achromatic condenser
was employed, because it brought out the (faintly seen) oblique
lines in many parts. ‘This view, so valuable to the optician, I have
never regarded, since attempting to photograph the scale long since,
as any indication of the real structure; and I should scarcely have
dared to figure it, after the beautiful drawings by the late Richard
Beck, and the splendid photographs of Dr. Woodward, save, as they
are so well known to microscopists, such a figure might, if placed in
the centre of the others, tend to the knowledge of the general struc-
ture, and facilitate the recognition of the different views given. I
may here mention that the scales were examined as opaque objects

* ‘M. M. Journal,’ No. XX., p. 67, and No. XXIIL., p. 261.

Royal Microscopical Society. 259

with the parabolic condenser, but without apparent advantage in
any respect.

It will be gathered from the foregoing and the figures that,
like some others (Drs. Pigott and Woodward, &c.), the spines
—“notes”!! are not regarded as having any existence as separable
bodies, but as due to the refractive nature of the rib at that part,
its thickness and solidity, and the direction of the incident light,
which opticians know so well how to arrange to the greatest advan-
tage in testing the general “performance” of their objectives—a
charming object, doubtless, yet not the whole truth! To quote the
words of one of our most skilled observers, the late Richard Beck,
when concluding his paper on the photographic appearance of the
section of the bossed tumbler, “ How can any reasoning be sound
when based merely on the appearances of the markings under the
microscope, which, as I have endeavoured to show, may be entirely
due to the peculiarity of the illumination, and may give not the
least indication whatever of the true structure ?” *

Nor are Dr. Pigott’s views considered as any way indicative of
the correct structure of the scale. The beads are regarded as marked
optical effects of refraction and interference where the junctions of
the longitudinal “ribs” by transverse and vertical septa take place
with the opposite membrane, by which we obtain, with the assistance
of the oblique attachments, the joint effect of short rods applied to
the long ones, and hence illusory, an opinion largely shared by
others. In relation to which, I may cite the optical effects pro-
cured by crossed glass cylinders, shown so beautifully in Mr.
Hennah’s photographs,; and which he very kindly sent me. The
pseudo-beads are 0 well represented as real beaded structure, that
the appearance would puzzle the most practised eye, and prove
how necessary to be guarded in the term beads as components or
definite parts of minute structure. {

Amongst other experiments, an attempt was made, in a rough
way, to try and split the scales of the wing of Pontia brassica. It
was cemented on one side to a glass slide by coloured turpentine
cement; then the wing was suddenly torn from the glass, trusting
to split some of the scales into thin layers. The scales were left
entire. The adherent scales were now subjected to the same violent
treatment, by attaching a slide to their exposed surfaces, but from
the scale bemg rendered so transparent by the cement, it was un-

* ‘Tntellectual Observer,’ vol. vii., p. 95.

+ See Report of Proceedings of Societies, M. M. Journ.,’ No. XXVIIL, p. 195.

t Several years since I made photographs of spun-glass hair cut into lengths,
then laid on thin glass covers, and attached to them by heat only ; next arranged
so as to cross or rotate over each other, either with the little rods touching, or
with one set resting on the free surface of the other thin cover, or with the free
surfaces of both covers in contact. The effects occasioned by interference were

highly curious and instructive. Unfortunately, the prints have been mislaid, or
they should have been added to the others.

VOL. Y. U

260 Transactions of the

certain whether one or two membranes were under view, though
evidently some were torn apart; nor was it possible to find with
the necessary certainty the corresponding portion of the scale on
the opposite glass. Perhaps if tried using only a few scales on a
thinly-varnished slide, employing a solution of wax in benzole or
chloroform, and covering them with a similarly-prepared stout
cover; when separated by force, the scales might be split. This is
only a suggestion arising from the previous experiment.

The examinations have been most fruitful on highly-dried or
old specimens from hot climates, when anatomized scales were
sought. The torrefying alluded to in the previous part has been
managed in the following way:—A clean cover had some scales
spread out on the centre and examined to see if it contained both
the simple and wavy kinds; then covered by a rather smaller thin
cover, and both carefully placed on a flat thin piece of iron plate
(the iron frame of the large linen-covered buttons answered well).
This was held by the forceps at one side, and gradually introduced
at its edge into the flame of a spirit-lamp. In a short time the
scales were seen to suddenly change colour, and become almost lost
to the naked eye. At this moment the support was withdrawn
from the flame, but kept at a greater distance from the source
of heat, to thoroughly dry the scales. Without the precaution of
covering the scales by a second thin glass, they were generally found
so contorted as to be useless. Much care is required, or they become
fused. The ribs sometimes separated unequally, the imterspaces
often giving rise to the optical effect of the “ notes”! ! (vide Fig. 18) ;
others shrivelled in various directions, and produced, with some
illuminations, most charming chromatic effects; others appeared
melted on to the surface, so that a needle could be made to divide
them or traverse them in any direction, without displacing the
scale. In some, nothing could exceed the beauty of the illusory
beaded appearance, both longitudinal and oblique. An attempt has
been made to figure the effect (Figs. 13 to 19); and in others the
transparent membrane was shown with a portion of the framework
attached. On bruising a thoroughly-roasted scale, there was no
evidence whatever of any beads being in or separable from the
scales. The particles of pigment that became detached in every
case, most likely from the pigmentary deposit, were very irregular
in size and shape (vide Fig. 8, from an untorrefied scale).

As regards the nature of the pigment, so called, it is feared
the views now offered may not quite correspond with the usually-
received opinions. A careful examination with reagents is needed.
I have not been able to separate it in quantity sufficient for this
purpose, though my friend, Dr. Southby, writes me from Italy,
where the Humming-bird Sphinx Moth (Macroglossa stellatarwm)
was plentiful, that he had been enabled to displace it from the sur-

Royal Microscopical Society. 261

face of the recent scale, so as to denude the ribs. Fig. 32 accom-
panied his remarks of date J anuary 1, 1871.* This would place a
pigmentary deposit outside the scale, and this portion I feel dis-
posed to regard either as an exudation of the material within,
through the scale membranes, or as the remains of the moisture
with which the wings are clothed at the time of emergence from
the chrysalis state, rather than as possessing any cellular structure
outside the scale. Hence the term here, “ pigment cells,” seems to
be objectionable. Where it existed in a finely eranular condition
within the substance of the scale, or on the boundaries of the areas
produced by the framework, the term “cell” seems less suited ;
but when in particular spots, or patches of any size, it may seem
more applicable, though by transmitted light it becomes most diffi-
cult to determine what is due to interference and what to accumu-
lation of coloured material. By the term “ pigment cells” we
virtually admit their cellular nature; thus it seems open to ob-
jection, seeing the term beads is also sub judice. Perhaps it would
be better to ‘speak of pigment granules where they can be seen as
so many separate fine dark or coloured specks in the membranes
and edges of the framework of the dark or coloured scales, and pig-
mentary deposit where a coloured irregular layer can be found in or
on the normal free surfaces. My. McIntire, in his correspondence,
which I take the liberty to quote, sugcests “this material never
thoroughly dries, and rough usage would modify its appearance ”

hence perhaps it "could be better studied as an opaque object, ten
a very tedious process with high powers; certainly torrefaction does
not much aid in its displacement, and finding this, | hoped more
from the use of strong sulphuric and nitric acids, but was disap-
pointed: other reagents may eventually aid in its study, for opti-
cally it is feared we shall not arrive at anything very definite.
For those scales which are nearly transparent, and where pigment,
as such, not necessarily of a dark colour, exists in a highly granular
condition, I would suggest that it should in such scales pass by the
name of pale granular pigment, or short, pale granules, and where
external, pale granular deposit, which would embrace those scales
which are of a silvery or pearly-opaque aspect, or which may be of
a dead white, varying to any tint of a light colour, even to brick

* “T enclose you a pencil sketch of part of a scale of the Humming-bird Sphinx.
I took the scales with my finger made quite dry from the living insect, then placed
them ona clean piece of glass, and took another piece and pressed it upon the first,
and gave it a roughish slide on the other; then examined the ill-used scales with
my ith object-glass, corrected for uncovered objects. The scale from which I took
the sketch was from the first, therefore the surface seen was the upper surface:
you will see that the rough treatment has luckily abraded the cuticle, if we may
so call it, on both sides, leaving the internal bars in places quite clean. The
under side is the same as the upper as seen in another scale.” My views make
the outer membrane or surface as the most transparent, and the inner as the chief
pigmentary membrane.

u 2

262 Transactions of the

red. This would not bind us to any theory, and give more de-
cision to our studies, yet quite open to improvements.

It is at the moment of emergence from the chrysalis the study of
this substance may be best undertaken, when perhaps the external
deposit may be made to adhere to the slide or thin cover. Or the
scale from the living insect taken for the examination of the gra-
nules within the substance. Possibly it is in the nature of the
pigment we may find the function of the scale, if endowed with the
property previously suggested.

Whether individually and collectively the pigmented scales may
share in the inherent power of “ mimicry” described by Bates and
Wallace, by which the bearer establishes a close but false resem-
blance to some of the creatures of its own kind, to avoid personal
detection, or to a different order or division of the organic kingdom,
as in the simulation of leaves by the leaf butterfly, not only im the
healthy condition, but also in “every stage of decay, blotched,
mildewed, pierced with holes, and in many cases irregularly covered
with powdery black dots, gathered into patches and spots, so closely
resembling the various kinds of minute fungi that grow on dead
leaves, that it is impossible to avoid thinking at first sight that the
butterflies themselves have been attached by real fungi ; *—

Or whether, as in the Heliconide, any power be shared by them
in common with other organs, of furnishing a disagreeable odour,
are questions bearing on the subject, but which, for want of speci-
mens, have not been examined ;—

Or again, whether the scales harmonizing beauty and utility
may not more directly than is generally suspected enter into rela-
tionship with the little amatory episodes of these insect creatures,
by adding increased brilliancy and splendour to the already highly-
attractive nuptial vestments of both sexes ;—

Or whether they may be individually or collectively wanting in
these endowments, and only modified by the local influences of
climate or food, must not be overlooked in their study. Of the
variability in Kallima paralekta, the under surface is described as
so “ variable in colour, that out of fifty specimens no two can be
found exactly alike, but every one of them will be of some shade of
ash or brown or ochre, such as we find among dead, dry, or decaying
leaves.”

My friend Mr. McIntire, who has given us such valuable par-
ticulars of the life and habits of some of the Thysanuradex, points
out that the change of skin takes place at the time when the scales
are in all stages of development, that the growth of the scales is
arrested, that they dry up and form a somewhat thick layer of
elastic corrugated plates on the delicate skin of the owner ; whereas

* See also Wallace’s “ Natural Selection,” “Malay Archipelago.”

Se

Royal Microscopical Society. 263

I suspect them to retain their freshness and be capable of effecting
such changes on the semi-solid material within, as shall keep the
scale in its normal state, especially as relates to the pigmented scales
in Lepidoptera. Mr. Wenham notices the scales of Lepidocyrtus
are limp as wet paper, and certainly it is difficult to unbend them
without damage when folded.

I would willingly cede these points, was it not deemed that the
pigmented scales require a fuller examination than they have yet
received at our hands.

How much of the iridescence of the scale may be due to light
reflected from a finely-ribbed surface, or from interference and
diffraction in its passage through irregularly-refracting portions,
occasioned by the inner framework, or to the fine pigment granules
in the substance of the scale, or to the pigmentary granular deposit
on the free surface, is doubtful ; but we must not overlook the fact
that where the pigmentary layer has been accidentally or purposely
removed, the chromatic effects are yet very perfect under oblique
illumination. It is assumed the pigment material largely determines
the general colour of the scale, as yellow, green, brown, blues, reds,
&c., of all shades, and the pearly or opaque white by reflected light,
perhaps by absorption.

For it was noticed, heat in charring the scale altered its colour
to the naked eye, most completely in the very iridescent scales,
while under the microscope their structure was not proportionately
changed, unless the torrefying had been carried to extremes when
parts were often displaced.

How much of the colour may be due to interference or the pas-
sage of the light through the object traversing substances capable
of affecting the velocities, bending them out of their course, more or
less diffracting or breaking them up into prismatic rays, and these
again suffering refraction and reflexion in various ways; to at last
meet with rays of certain velocities, which either swell their amount
of colour, or interfere by want of harmony in their undulations, and
either reduce them or modify them, so as to furnish several com-
pound colours in all parts of the object, of more or less corresponding
power over the original light, and with interference shadows in
addition, is a question open to considerable doubt, if not defying
human skill.

And when the phenomena of colour in its complementary cha-
racters embrace more than two colours, due in part to the nature
of the object and in part to the final corrections given to the ob-
jective by the optician, the subject becomes much confused by
furnishing a mixture of interference spectra, very charming to the
eye, as in Figs. 5 and 267, but useless in the analysis of structure.
Yet if the adjacent parts be not sacrificed in definition, an additional
aid may be found for increasing our knowledge of intimate struc-

264 Transactions of the

ture, as with polarized light, though, if we disregard the appearances
produced by other methods of observation and illumination, which
furnish a better clue to the real structure, without marked chro-
matic effects, we shall be in constant danger of accepting illusory
appearances.

To the terms “ ribs,” “ cross-bars,” at first sight there may ap-
pear some objection ; but when the figures are examined where the
rib and its attachments are seen together stripped from the scale
(Fig. 2), the terms seem to me less objectionable than “ corruga-
tions” “ folds,” or “strie.” Now, Mr. Slack sees in the ribs “ only
corrugations or wrinkles” in the butterfly scales, and I think Mr.
McIntire and others prefer these terms to “ribs”; hence it is with dif-
fidence the former are employed, for terms used to convey appearances
under the microscope are seldom quite satisfactory. Mr. Slack says,
“the beads more or less distinct, or coalescent, as the case may be,
I take to be formed by exudations, in drops, from the membranes,
consolidating, so far as they do consolidate, in a definite form.”*
This view appears open to considerable doubt, though a kind of com-
promise of different theories and contrary to the one adopted in this
article, which is perhaps more advanced in particulars than sug-
gested by my friend Dr. Woodward in the recent pages of the
‘Monthly Microscopical Journal,’ No. XXVIII., p. 158, or than
pointed out by that careful observer Mr. McIntire. Theinner mem-
brane appears slightly extensible, the ribs can be compressed out of
shape in some scales, and in none did they appear to me hollow, as
Dr. Bowerbank suggests: a communication through the quill to the
inner surfaces is suspected to exist in all scales, and in relation with
the membranes of the wing or dermiec support.

Whether the butterfly would show any change in the general
colouring of the wing, by the transmission of feeble electric shocks
through the living insect, is doubtful, though perhaps worth an
experiment It will be seen that I am disposed to give to these
flattened bladder-like bodies some function, higher than is usually
supposed, though the transition from hairs “ protective” and
“ornamental” is so gradual towards their own varied shape and
substance, that they appear more naturally to accord with those
ordinary dermic structures. Possibly they may be expended tegu-
mentary organs, which passed their active phase in the chrysalis
state, and merely preserved a common attachment upon emerging
from this condition. Mr. McIntire points out + the moment they
become external appendages they cease to grow; yet does it follow
that all changes in the material within the membranes of a semi-solid
greasy nature are checked, or are not kept in a normal condition
fcr the benefit of the scale? To some alteration in this material

* ‘Student,’ No. 1, p. 54. + ‘M. M. Journal,’ No. XXYV., p. 6.

Royal Microscopical Society. 265

the pigment seems -due, and should be referred. It is a point for
further investigation and quite open to inquiry.*

It seemed to me some attempt might be made on a large scale
to ascertain whether if two artificial arrangements based on the
figures given of the Lepidoptera scale, which also furnished when
charred the appearance of the “notes”! ! and of “beads,” would, when
placed facing each other, furnish an image of beading after the views
of Dr. Pigott, when direct sunlight was allowed to traverse them.
Hence a large very rude pencil sketch (Fig. 31) was made of
Fig. 15 ; over this was laid a clean piece of glass ; the “ ribs and cross-
bars” were then followed roughly with a composition consisting of
mastic dissolved in chloroform and just tinged with aureolin (ground
for oil painting), and laid on very thickly in the course of the ribs,
lightly over the bars. When dry the plate was reversed, and on
this was placed another piece of glass; the ribbings and cross-bars
showing through, were then followed in the same manner with a
sable pencil charged with a mixture of mastic, wax, and chloroform,
untinged and laid on thickly over the ribs, less so over the trans-
verse and oblique bars. When dry these glasses were placed oppo-
site each other at apertures cut in a narrow box, all the light being
excluded from beyond the outer edges of the figures, and then held
up to sunlight, the image being received on glass dulled (by amber
varnish used cold and allowed to chill), placed at variable distances.
After a little patience and manceuvring a beautiful dotted or beaded
image was shown on the glass, all trace of ribs and cross-bars had
disappeared. 'This was several times shown to others, and finally
received on a sensitized collodion plate which furnished the negative
from which the photograph (Fig. 27) is printed: the lenses were
removed from the camera, so that the effect of diffused light through
the transparent spaces has given a rather weak image.

The camera was shifted, the lenses inserted (4 plate, Voight-
lander) and eight negatives were taken of different appearances; un-
fortunately in varnishing them the collodion cracked, and too sadly
marred the image to be of any use, but the figures of three are added,
as also the coarse pencil sketch of Fig. 15. In Fig. 28 a resem-
blance exists to one view of Degeeria domestica. In Vig. 29 several
bright-beaded spots will be noticed on the “ ribs” and their generally
beaded aspect; a dark shadow between the “ribs” and their
coalescence.

In Fig. 30, to the left of the figure in the negative are two
lines composed of distinct small dark spots (“ beads” ?), but so much
more delicate than the rest of the image, that they are almost lost
by printing the detail of the other parts, which, before injury by the
action of the varnish on an old collodion, gave a medium image

* Vide Watson “On Plumules,” ‘M. M. Journal, No. VIIL, p. 77, and
No. XII.

266 Transactions of the

between Figs. 28 and 29, partaking of both. Of course the repre-
sentation was too rude to positively assert that the beaded structure
of the insect scale arises from interference and diffraction, &e.; but
it has its value as bearing on the opinions and figures contaimed
in this imperfect sketch.

Photography would have been used more largely, had I not learnt
from experience that some of the appearances would not have been
easy to record without very considerable trouble, especially as the
season was not sufficiently advanced to undertake the experiment
with either comfort or certainty.

Every care has been taken to render the objects as seen, but to
obtain the prismatic effects with all their charm and vigour was
hopeless. ‘To quote Mr. Slack’s words, “It is only by combining
all the appearances which seem to give real information, that we can
expect to arrive at a true conception of structure ;” as aids there-

fore to others, rather than as dogmatic assertions, it is hoped the ©

foregoing remarks will be received by the Fellows of the Society,
to whom I beg to offer every apology for such “dry as dust” de-
tails, in venturing to attempt some explanation of the wondrous
contrivances, endowed by the Creator with the property that sheds
a lustre, both on the gay and gaudy visitor of the hour, or the
silent and agile tenant of the dreary cellar.

——

ee ee a r

The Monthly Mieroscovical Journal. Jane 11871. PL LARA

| | in | |
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7

Royal Microscopical Society. 267

Il1.—On the so-called Suckers of Dytiscus and the Pulvilli of
Insects. By B. T. Lownz, M.R.CS.

(Read before the Rovau Mrcroscoricat Society, May 3, 1871.)

Tue anterior pair of feet, in the males of the Genus Dytiscus and
its allies, are remarkable for their widely-dilated tarsi. These are
well known to microscopists on account of the sucker-like disks
with which their under surfaces are furnished. The middle pair of
tarsi, in these insects, are also furnished with disks on all their joints,
in the males only. The function of the disks in both cases is to
assist the male during the act of sexual union. They are entirely
absent in the female.

The disks are nothing more than remarkably-developed pulvilli,
although their adhesive power is usually attributed to atmospheric
pressure; hence they are frequently spoken of as the suckers of
Dytiscus.

The simplest form of pulvillus is seen on the tarsus of some
plant-loving beetles, and especially amongst weevils. I have
selected the beautiful foot-pad of the Australian diamond beetle as
an example.

The under side of the tarsus of this insect is densely clothed
with a velvet-like pile of golden yellow hairs. Fig. 11 represents
two of these hairs seen with a quarter-inch objective and C eye-
piece by Ross. They are seen to be tubular, with slightly bulbous
extremities. The wall of the bulb is thinner than the rest of the
hair. The bases of the hairs are connected with and open into a
large gland occupying the interior of the tarsus. This secretes
a viscid tenacious fluid which fills the cavity of the hair and exudes
through the walls of the bulb, thus enabling the insect to obtain a

EXPLANATION OF PLATE LXXXIX.

Fic. 1.—The anterior tarsus of a male Dytiscus, with the integument of the upper
surface removed to show the gland which secretes a viscid fluid for
the supply of the disks. a, tendon of claw; b, main tracheal vessel
and sac. A portion of the sac is removed above to show the openings
into the disk-bearing hairs.

2.—One of the smaller suckers.

3.—Vertical section of the large sucker. a, c’, a, under side of the tarsal joint ;
6, external elastic membrane; c, columella; ec’, opening into gland;
d, e, f, membrane of disk; g, chitinous cone in the centre of the disk;
h, h, membrane of the gland.

4.—Disk of the large sucker; a, ovate space without radiating fibres.

», 9—TInternal orifice of the columella of the large sucker seen from the interior

of the gland.

,,. 6.—Tranégverse section of the disk of the same near the pedicle.

., 7.—Section of the disk near the margin.

,, 8.—A portion of the margin of the large sucker.

,» 9.—Tuft from the same.

, 10.—Gland hairs from the foot of the blowfly.
, 11.—Gland hairs from the foot of the Australian diamond beetle.

268 Transactions of the

firm hold on the vertical surfaces of trees and the under sides of ©

their branches.

In flies we find an exactly similar arrangement, except that the
hairs are extremely minute and delicate, and that they have their
bulbous extremities flattened into disks. I have already drawn
attention to these structures, and to the manner in which the discoid
hairs are detached, in my work on the Fly. I may now repeat,
however, that although when all the hairs have the strain put upon
them equally they suffice to support the insect, each row may be
very readily removed separately. This is done by the manner in
which the tarsus is raised. The same seems to be the case in other
insects.

In Dytiscus the pulvillus, or sucker as it is sometimes called,
consists of much larger and more complicated hairs. I think, how-
ever, there can be no doubt it is a mere modification of the usual
form of pulvillus, found on the feet of other beetles, flies, and a host
of insects.

There are about 200 disk-bearing hairs on the anterior dilated
tarsus of Dytiscus marginatus, punctulatus, or cirewmfleaus, the
three common British species. ‘Iwo of the disks on each tarsus
are of remarkable size, and differ in several points beside size from
the remainder. The largest of the large disks is situated on the
posterior portion of the proximal tarsal joint, close to the tibia, and
usually measures ;/;th of au inch in diameter. The smaller is about
half this diameter, and is situated in front of the larger. The other
disks cover the remainder of the dilated portion of the tarsus, and
are not more than about +}5th of an inch in diameter. The middle
pair of tarsi have their under side clothed with a dense pad of disk-
bearing hairs similar to the latter.

If the integument of the upper surface of one of the anterior
dilated tarsi be carefully removed, the cavity of the tarsus will be
found to be occupied, in great part, by a large but delicate sac. ‘Lhe
main trachea with its sacculus and the tendon of the last tarsal
joint will be seen lying upon it, and these occupy all the remaining
space in the cavity of the tarsus. The sac will be found full of a
gelatinous viscid substance, the same as that which exudes from the
hairs. It is well supplied with tracheal vessels from the main
tracheal trunk, indicating that it is an active secreting gland. If
a portion of the upper part of the sac be removed, and its contents
cleared away with a camel’s-hair pencil, the internal orifices of the
disk-bearing hairs of the pulvillus will be seen distinctly in the
centre of nipple-shaped projections of the integument which project
into the sac. Such a preparation, with a portion of the walls and
contents of the sac removed, is represented in Fig. 1.

The largest disk is most easily examined ; and a vertical section
through its centre is the best mode of showing its structure. Such

Ee eeEEE———EE——K= Se ee eee

Royal Microscopical Society. 269

a one is represented in Fig. 3. It consists of a pedicle, b, attached
to a dome-like depression on the under side of the tarsal joint,
a,c’, a, and a disk, d,e, f. The upper surface of the dome-like
depression forms the elevation already alluded to as a nipple-shaped
projection into the interior of the tarsus. The secreting sac is
closely united to its margin and is represented at h, h; its apex is
perforated at ¢’.

The pedicle consists of an elastic external membrane, b, thick-
ened into a chitinous ring around its junction with the disk, and
lined with epithelium. It is hollow, and strengthened by a hollow
columella, c, which is open along one side of its whole length. The
disk is a flattened membranous sac, continuous with the outer
membrane of the pedicle above, and in this it differs only in size
from the hairs already described from the fly. The disk is strength-
ened, however, by numerous radiating fibres between its layers,
which arise from the columella. This consists of a hollow bundle
of chitinous fibres, which are attached above around the opening in
the dome, c’, and below by a speckled cone of chitine, g, to the
centre of the disk. ‘The fibres pass over or through this cone in a
radiating direction, and become applied closely to the lower mem-
brane of the disk. Here they branch dichotomously, and ultimately
unite, at about one-third the diameter of the disk from its centre,
with both membranes. They then run straight to the margin of
the disk, leaving channels between them, through which the viscid
secretion from the tarsal sac passes. This secretion fills the cavity
of the hair, which it enters through the columella. The extremi-
ties of the radiating fibres on the margin of the disk, invested by
a prolongation of its wall, form a dense fringe of brush-like tufts
around its circumference. An ovate space on the surface of the
disk (Fig. 4, a) may be observed destitute or nearly destitute of
radiating fibres: it corresponds to the open side of the columella.

I have been unable to discover how the secretion is prevented
from flowing from the disks when they are not in use, but I suspect
this is effected in the following manner. When the disks are at.
rest they are cup-shaped ; when they are applied to any flat surface
they become flattened out. The cup-shaped, form of the disk is
maintained by the elasticity of the outer wall of the pedicle. This
keeps the columella stretched, and I suspect keeps the slit in its side
closed. As soon as the disk is flattened the tension is taken off
the columella, and I suspect its slit gapes just as a bundle of strings
kept together by tension upon their ends separate when held loosely.

The smaller of the large disks is exactly like the larger, except
in size. The small disks differ, however, from the large ones in
haying no columella and no fringe. The pedicle is differently
shaped, being pointed at its junction with the disk. The radii of
the disk are very delicate, and terminate in the centre of the

270 Transactions of the

internal surface of its inferior membrane. The small disks are’

cup-shaped when at rest, and are not placed at right angles to the
pedicle, but obliquely to it. When in use they are flattened and
brought at right angles to the pedicle. This opens a communica-
tion between the cavity of the disk and that of the pedicle, and so
with the secreting sac.

If we compare the structure of the smaller disks with that of
an ordinary insect’s hair, we shall find they differ only in form.
Each consists of an external structureless layer, an internal cellular
one, and a cavity. The gland connected with the base of the hairs
of the pulvillus is also represented in other hairs. Several cater-
pillars have a hollow poison gland at the base of certain hairs,
which is very similar to the tarsal sac of perfect insects. Both are
probably a mere modification of the internal cellular layer of the
hair, which is itself only a modification of the internal cellular layer
of the integument. For hairs in insects are mere processes of the in-
tegument itself. In the larger disks we have the columella added to
these structures ; but this is clearly only a modification of the cellular
layer, which becomes fibrous in all the larger hairs of insects. ‘The
differentiation of the cellular layer of a hair into a fibrous and cel-
lular layer, separated by a large space, is a very remarkable modifi-
cation of the ordinary structure: it is, however, in my opinion
nothing more. The structure of the gland in the tarsus is so deli-
cate, and its contents coagulate so readily, that I have been unable
to make out whether there is a single locculus for each disk, or
whether the cavity of the gland is single. In either case I look upon
it as a mere modification of the internal cellular layer of the integu-
ment, and identical with the poison glands connected with the
hairs of caterpillars already alluded to.

With regard to the functions of these hairs, Mr. Blackwall, in
a paper “On the Pulvilli of Insects,” as long ago as 1816, showed
so completely that most insects climb vertical surfaces or walk on
inverted ones by the aid of a viscid fluid exuding from the hairs on
the under side of the tarsus, that I feel some apology is needed in
reviving the subject. ‘The opinion is, however, very prevalent that
the phenomenon is due to atmospheric pressure acting on vacuum
suckers. This has been repeated so often by good observers in the
case of the fly, and more especially in the case of Dytiscus, that I
shall venture to give the evidence we possess upon the subject with
regard to the adhesion of the latter. For so far as I know, no one
has hitherto denied that this insect adheres by means of atmospheric
pressure.

I will now repeat before you an experiment upon Dytiscus first
suggested by Mr. Blackwall, and made by him upon the fly, with
certain slight modifications made necessary by the nature of the
insect. I have here a male Dytiscus rendered insensible by the

ee

Royal Microscopical Society. 271

action of chloroform. I apply its four anterior tarsi to the interior
of an air-pump receiver. By pressing these slightly with the side
of a needle they adhere firmly to the glass, and the insect remains
suspended in its interior. I now exhaust the air, and the insect
still remains suspended. It is necessary to render the insect insen-
sible, otherwise it voluntarily detaches itself. To my mind this
experiment is quite conclusive.

The evidence afforded by the print of the foot of Dytiseus upon
a clean glass slide is very conclusive, as every hair leaves an im-
pression in a viscid semi-fluid material upon the glass. The fringes
on the large disks are usually loaded with an abundant supply of
this viscid glue.

Again, if the suckers be examined whilst in action, they will be
found either to contain air or fluid, or to be applied quite evenly to
the surface on which the insect is holding. This may easily be
done with an aquarium microscope, or by enclosing the insect in a
large live-box, with its feet upwards.

It will probably be argued that a partial vacuum may be
formed by the elasticity of the suckers themselves ; but, admitting
this to be the case, its only effect would be to cause an increased
flow of viscid fluid from the surface of the disk, and hence it could
not aid the insect in adhering to any surface.

The nature of the adhesive fluid has not yet been ascertained,
but it coagulates rapidly, is insoluble in water, and solidified under
that fluid. Its surface is slightly greasy, so that water runs off
from it, and it cannot be wetted. I have been unable to find any
solvent that will dissolve it.

In conclusion, I may remark, that I have several times found
beetles which have lost many of the tarsal disks, their places being
marked by dark-brown chitinous cicatrices. I think this is due to
the insects having become too firmly glued to their mates during
copulation, so that they have been unable to escape without leaving
their disks behind them. This closely resembles the adhesion of
flies to our window-panes in autumn ; the tarsi becoming so firmly
fixed in enfeebled insects that they are unable to escape.

(5978.9

PROGRESS OF MICROSCOPICAL SCIENCE.

Embryology of Insects —Mr. A. 8. Packard, jun., has furnished the
Peabody Academy of Science with a very valuable series of papers on
Diplax, Perithemis, and the Thysanurous genus Isotoma, which have
just been published. The author enters fully on the development of
each insect, and illustrates his observations both by several woodcuts
and by a series of most valuable and carefully-drawn plates. He
states that in certain mites, as Hydrachna, Pontarachna, Thalassa-
rachna, and probably all the Hydrachnide, the ocelliare situated over
the second pair of legs at a considerable distance behind the head. In
a genus of Annelids (Polyopthalmus) organs of sight are developed
on each ring of the body, or, as in certain Planarians, scattered irre-
gularly over the body. In the embryo of Isotoma and Diplax the
ocelli are evidently developed on the antennary segment, as they are
epithelial cells primarily situated on the cephalic lobes, which seem
to form the tergite of the antennary segments. With this view, the
supposition he has expressed (led thereto by the generally-received
opinion of Milne-Edwards, Dana, and others, that the eyes of insects
and Crustacea represent limbs and therefore demand separate segments)
seems incorrect. Accordingly, he thinks we are forced to the belief
that the head of the hexapodous insects consists of but four segments,
i.e. the second maxillary, first maxillary, and mandibular segments,
situated behind the mouth-opening, and the antennary, or first and
preoral segment, situated in front of the mouth. The cephalic plates,
which fold back upon the head, forming the main expansion of the
insectean head, is apparently the tergum of the antennary segment.
The clypeus and labrum are apparently differentiated from the cephalic
lobes, and thus seem to form a portion, or fold, of the antennary seg-
ment. These cephalic lobes in the Arachnids are described and figured
by Claparéde as folding back on the top of the mandibular and maxil-
lary segments, bearing ocelli and forming the anterior wall of the
mouth. The upper part of the head of an insect is, then, largely
tergal, rather than pleural as previously stated by him.

Structure of the Bat’s Wing.—This, which has long been a mystery,
has now been solved in an able paper by Dr. Joseph Schobl, of Prague.
According to him, the bat’s wing membrane consists of two sheets of
skin, the upper derived from that of the back, the lower from that of
the belly. The epidermic and Malpighian layers in each sheet remain
separate, whilst the true skin is inseparably fused. In this fused
medium layer are imbedded the muscles, nerves, vessels, &c., of the
wing. A complicated arrangement of delicate muscles is described,
which have their tendons formed of elastic tissue instead of the usual
white fibrous tissue. There are also present numerous long elastic
bundles stretched in different directions in different regions of the
wing. The arteries are each accompanied by a single vein and a
nerve, the three keeping company as far as the commencement of the

PROGRESS OF MICROSCOPICAL SCIENCE. Na

capillary system. With regard to the pulsation in the wing, Dr. Schébl
has nothing new to add to the observations of Wharton Jones and
Leydig. The whole wing is covered, both on the upper and under
surface, with extremely fine, sparsely-scattered hairs. These hairs
are most numerous on the inner third of the hinder part of the wing,
and they gradually decrease in number towards the tip. The two
wings, taken together, contain from eight thousand to ten thousand
of them. They have a general resemblance to those on the body, but
are simpler inform. Their length is about 0:2500™™ in Vesperugo
serotinus, the species principally made use of in these investigations.
Each hair sac has from two to seven sebaceous glands, according to
the species, and one sweat gland opening into its sac. The two outer
fibrous layers of the hair sac have no sharp line of demarcation to
separate them from the surrounding connective tissue, but the inner
or hyaline coat is highly developed, and, after being constructed
beneath the hair bulb, widens out and encloses the sense-bodies
(Tastkérperchen), one of which organs is connected with each hair.
The nerves of the wing may be considered to consist of five layers,
i.e. there is one occupying the centre of a transverse section of the
wing, which gives off on each side of it four others, and these are
successively finer and finer as they approach the opposite surfaces.
The inner layer and the one immediately on each side of it, consist
of nerve fibres with dark borders, the other layers of pale fibres only.
The tastkérperchen are connected with the second layer. The fifth
layer of finest fibres ends as a network between the innermost layer of
cells of the Malpighian layer of the epidermis. The tastkérperchen
are shaped like a fir-cone with a rounded apex turned inwards. They
lie immediately below the root of the hair; and their core or central
substance is formed of a prolongation of the cells forming the two
root sheaths of the hair. Their length is 0°0259 and their breadth
0:0175"". A nerve containing about six dark-edged fibres is distri-
buted to each kérperchen. Just before the nerve reaches this organ
it splits into two, and three fibres pass to one side of it, three to the
other. The fibres are then wound round the body so as to sheathe its
cellular core. Dr. Schébl thinks it probable that the fibres on one
side are continuous with those on the opposite side, and that there is
thus a bipolar arrangement here. He attributes to the fine network
of pale nerve fibres belonging to the fifth layer the appreciation of
temperature, pain, &c.; to the tastkérperchen the highly-exalted sense
of touch. It is curious that both kinds of nerve endings are connected
with the Malpighian layer of the skin. In conclusion, the author
states that he believes he has found similar bodies in peculiarly
sensitive places in other mammals, and promises an early account of
them.

The Structure of Chitons is being investigated by Dr. P. P. Car-
penter, who, we understand, lately communicated a paper upon the
subject to the Boston Natural History Society. The paper will be
published soon by the Smithsonian Institution.

Microscopy at the American Association.—This Association, which
will hold its next meeting on the 16th of August next, will continue

274 NOTES AND MEMORANDA.

its formation of a separate section for microscopy, and we haye no
doubt that the results will even excel those which we have long since
reported from the last session. The ‘ American Naturalist’ suggests
to the local committee the propriety of supplying a room with proper
light and substantial tables for the occasion. We hope this recommen-
dation will be attended to.

Colossal Fossil Sea-weed.-From the microscopic examination of
the structure of specimens of the fossil trunks described under the
name of Prototaxites Logani, and which Principal Dawson affirmed, in
his Bakerian lecture before the Royal Society, to be the oldest known
instance of coniferous wood, Mr. Carruthers has (says ‘ The Academy ’)
discovered that they are really the stems of huge Algz, belonging to
at least more than one genus. They are very gigantic when contrasted
with the ordinary Alge of our existing seas; nevertheless, some
approach to them in size is made in the huge and tree-like Lessonias
which Dr. Hooker found in the Antarctic seas, and which have stems
about twenty feet high, and with a diameter so great that they have
been collected by mariners in those regions for fuel, under the belief
that they were drift-wood. They are as thick as a man’s thigh.

NOTES AND MEMORANDA.

On Bleaching Diatomacee, &c.—Dr. R. L. Maddox sends us the
following valuable note :—The structure of the silicious valves of the
Diatomacee, so largely engaging the attention of many microscopists—
though seldom before the entire destruction of the endochrome by
nitric acid or other agents—I beg to offer for their notice, from some
experiments conducted lately in bleaching both marine and fresh-
water forms, the use of chlorate of potash and hydrochloric acid as
likely to prove very useful in the examination, not only of the skeleton,
but the disposition of the endochrome; and it seems probable the
same may be employed with success on the minute Alge and minute
forms of organic life commonly accompanying them in the collection.
The proportions used have been varied, but about 40 grains of the
crushed chlorate to 13 drachm of the acid in 1 ounce of water, placed
in a 2 or 3 ounce phial, closed with a waxed cork, may be taken as
the average proportions: the action of the evolved chlorine com-
mences after a short period, and can be watched or modified as re-
quired. The use of this mixture for the examination of chitinous
structures in insects was advocated by Dr. Hicks; but I am not aware
of its having been extended to the Diatomacee; therefore the sug-
gestion is made in the hope it may be found useful by those engaged _
in the examination of the organization of these very interesting
objects.

CORRESPONDENCE. 275

Extra Meeting of the Royal Microscopical Society. — We are
happy to say that the R. M. S. has determined to give an extra meet-
ing this year in July, and if found convenient, to continue it every
year for the future. We hope, therefore, that a good assemblage of
Fellows will prove to the Council that they are not mistaken in be-
lieving that the vacation is too long at present. The extra meeting
this year will be held on the second Wednesday instead of the first,
owing to the College being unable to spare the rooms on the first
Wednesday.

Committee for Testing Objectives. —'This, which has been pro-
posed in a letter to us by Dr. Pigott, is favourably noticed in the
‘American Naturalist’ (May). We think that the writer’s suggestion
is a good one. It is as follows :—As this subject is largely an inter-
national one, though not of sufficient importance to call for the meet-
ing of a committee representing the different countries chiefly inter-
ested, any movement, if made at all, in reference to it, should be a
concerted movement in England, Germany, France, if practicable, and
this country, the same lenses being sent for study from one country to
the other. Microscopists might thus be informed, n6t as to which
objectives are the “ best,’ but as to which desirable qualities are pos-
sessed in an eminent degree by the lenses of the various makers.

Eyesight and the Microscope. — Under this title there is a short
but useful paper in the ‘ American Naturalist’ for May. We merely
direct our readers’ attention to it, as it is too long for quotation.

Spore-cases in Coals is the title of a very valuable paper by Pro-
fessor Dawson, in the ‘American Journal of Science’ (April). He
adds to his lectures, delivered in London, and to Professor Huxley’s
well-known researches, some facts of interest. It is well to point out
that this subject was almost first investigated in this country by Pro-
fessor Morris, to whom the writer gives credit for his researches.

CORRESPONDENCE.

Movntine Diatoms.
To the Editor of the * Monthly Microscopical Journal,’

Sir,—In the number 24 of the ‘Monthly Microscopical Journal’

Captain Knight exposes the difficulties which may be encountered by

‘those who wish to avail themselves of the method for selecting and
arranging symmetrically diatoms, as exposed by Captain Lang.

If diatoms are rare, I should try butterfly’s scales; I may presume
to affirm they are very good substitutes as objects, which being equally
interesting, permit one to acquire the greatest dexterity. I have
been successful beyond the most sanguine expectations, and I work
very easily with ** power (x 55 linear).

VOL Ve x

276 CORRESPONDENCE.

But I do not want chloroform, nor benzole, as suggested by
Captain Lang; and I dispose the scales, not upon the cover, but upon
the slip of glass itself.

As to the Canada balsam, I take great care to use that quantity
which will spread under the cover, and no more.

Thence no washing or cleaning, which is always a very tedious if
not a very dangerous process.

Your obedient servant,
Cuev*. F. Huyrrens pz Trrseca.
Brussexs, April 22, 1871.

On CELLS.

To the Editor of the ‘ Monthly Microscopical Journal.’
RocHEFORT-SUR-MeEr, April 14, 1871.

Sir,—I read with interest in last December’s number of your
excellent Journal a note on the method of selecting and mounting
Diatomacee, written by Captain Lang, President of the Reading Micro-
scopical Society. Certain cells made of gold size by. Captain Haig, a
very skilful micrographer, are described in it. He states that cells of
gold size may be exposed to intense and prolonged heat, through the
action of which they become perfectly black and carbonized, while
the Canada balsam is unable to alter them. The process which he
describes for calcining such cells requires a great deal of time and
some trouble, and I see no need for its adoption. Excellent cells for
microscopical preparations may be made of Bitwme de Judée (which is
naturally black), of asphalte, or of marine glue dissolved in spirit of
turpentine or in benzine. If the smoke, or rather the vapour, dis-
engaged from gold size, already calcined, and heated again, is apt to
form crystals, much more strongly must this effect take place when
bitumen, not previously heated to excess, is used. In order to remedy
this inconvenience, I have been accustomed to prepare beforehand a
number of cells, and so to have always at hand some dozens of slides
ready for use; but at the moment of using them I do not expose them
to heat. Formerly, in order to make the cover adhere, I used to apply
a second layer of varnish over the first. This sometimes caused an
inconvenience more serious than the one already pointed out. The
new bitumen spread itself gradually into the preparation, and at last
altered it completely. There is a very simple means of avoiding this
danger, and I will now describe it. A circle of bitumen, about one-
third smaller than the covering glass, is drawn beforehand on my
slides. When I wish to make a preparation, instead of coating, as
formerly, the first circle with a second layer of bitumen, I form a
second circle of it outside the first, and as near as possible to it, and
each of the two circles has its own advantage; the first, in fact, while
forming the cell, serves as a support for the covering glass, and thus
preserves the Diatomacez from any breakage ; it offers besides a serious
obstacle to the spreading of the more liquid bitumen of which the out-
side circle is composed, and the latter closes the cell by fixing the cover,

PROCEEDINGS OF SOCIETIES. 2G

which, when the preparation is dry, may be covered with a final circle
of bitumen. It is of course understood that I am speaking of prepa-
rations made in the dry way only, and not with balsam.
T hope this communication may be useful to your readers, and enable
them to escape many a failure.
I remain, Sir, yours,

Movcuet, H.F.R.M3S.

An Error.
To the Editor of the ‘ Monthly Microscopical Journal.’

Mosrecm or Comparative Zoo.oey,
CampripcE, Mass., April 10, 1871.
Dear Srr,—In my letter to Mr. Charles Stodder, published in your
March number, there is a misprint. In the fifth line, the word “spe-
cial” should be “spectral” ; it should read, “ with no spectral lines.”
By making the above correction you will oblige

Yours truly,
K. Bicknext.

PROCEEDINGS OF SOCIETIES.*

Royan Microscopican Socrery.
Kine’s Contece, May 3, 1871.

Dr. Braithwaite, F.L.S., in the chair.

The minutes of the last meeting were read and confirmed.

A list of donations to the Society was read, and a vote of thanks
given to the respective donors.

It was announced that the Council had been advised that it would
be convenient to many of the Fellows to have one more meeting
during the session than it had been the custom to hold. The session
had usually terminated in June; but as many Fellows would be in
town in July, the Council had thought it practicable to hold a further
meeting, subject to permission from the College authorities, on the
second Wednesday of July, the College being occupied on the first
Wednesday, which otherwise would have been chosen. If the expe-
riment should succeed, and a desire were expressed for its repetition,
the Council would take the bye-law relating to the subject into con-
sideration, with a view to its alteration, in order that the session may
close in July instead of June.

* Secretaries of Societies will greatly oblige us by writing their reports legibly
—especially by printing the technical terms thus: H y dra—and by “ underlining ”
words, such as specific names, which must be printed in italics. They will thus
secure accuracy and enhance the value of their proceedings.—Ep. ‘ M. M. J.’

we

278 PROCEEDINGS OF SOCIETIES.

Mr. Ladd described an addition he had made to the microscope,
which he had found very useful in examining double axial crystals
with polarized light. Generally speaking of the apparatus employed,
the polariscope was a very expensive instrument. The little appa-
ratus he had devised could be applied to any microscope with very
little trouble and cost. In the construction of it no new principle
was involved, although the application was new. Under the stage
of the microscope is placed a deep lens, beneath this another lens
not quite so deep, the ordinary Nichols’ prism being added in the
usual manner. Above the stage this arrangement of lenses is re-
peated. The draw-tube of the microscope must have another lens;
it is useful to focus the object of the draw-tube. The eye-piece used
was the ordinary A eye-piece, with the Nichols’ prism over it in the
usual way. The advantage of having these lenses was that a wider
range of field was obtained, for by the arrangement described the two
axes of sugar could be brought into the field ; and it was well known
that it required a large view to take in those two axes. The arrange-
ment works better by daylight than by lamplight. He had seen
another instrument that day at Mr. Powell’s, but it would not be
possible with that to bring in the two axes of sugar.

The following note was read from Mr. Suffolk :—

““CLEREMONT LopeE, PARK STREET, CAMBERWELL,
April 27, 1871.

‘“‘ GuNTLEMEN,—I forward herewith preparations of vegetable fibres,
and chiefly from specimens supplied by Dr. John Forbes Watson,
Reporter on the Produce of India, and by whose kind permission I
am enabled to present the accompanying specimens. ‘To these I have
added one or two received from Kew, and two slides of recent fibres
grown by myself.

“The chief value of the whole is as a trade collection rather than
as a botanical one; they are arranged as the duplicate series is in my
own cabinet.—Manufactured materials, not only including spun and
woven fabrics, but also fibres obtained therefrom.

“T hope during the winter session to give the Society a paper in
explanation.

“Yours truly,

“ W. T. Surrouk.

‘To THE SECRETARIES OF THE ROYAL
MIcROSCOPICAL SOCIETY.”

Dr. Braithwaite said, that as the number of fibres produced by the
vegetable kingdom useful for textile fabrics was increasing every year,
it was a very great advantage to have the actual notion of the nature
of the fibres produced by certain plants as objects of comparison when
working in that department. He proposed a vote of thanks to Mr.
Suffolk, which was unanimously passed.

A paper by Dr. Maddox, “On the Structure of Lepidopterous
Scales, as bearing on the Structure of Lepidocyrtus curvicollis,” was
then read.

Mr, Slack said, if Dr. Maddox had found the pigment in the scales

fad

PROCEEDINGS OF SOCIETIES. 279

disposed in the form of beads, the appearances were a confirmation of
his own views on the matter of dispute.

Mr. Hogg said the effects produced by Dr. Maddox were obtained
while the scales were in a torrefied condition. He (Mr. Hogg) had
also made experiments on the torrefied scales in the way proposed by
Mr. Wenham. The pigment seemed to run up the longitudinal
markings, giving a continuous effect, and under the th immersion
lens, which showed them remarkably well, the notes of exclamation! !
were quite destroyed. No doubt the structural characteristics of
scales can be better studied in the larger species of the Lepidoptera,
as Dr. Maddox has pointed out in his valuable paper, when it is found
that they are not inserted “as tiles are in the roof of a house,” but
are as much of an outgrowth of the dermal structures as are the hairs
of animals or the feathers of birds. Their bulbous extremities, being
firmly imbedded in the membranous wing, and filled with an albu-
minous or fatty colouring matter, this flows up the shaft, permeates
the tubules, or series of longitudinal folds, for the purpose of nou-
rishing the scales, in precisely the same manner as the epidermal
structures covering animal bodies derive nourishment and are main-
tained in health. These closely-placed tubules filled with colouring
matter give the iridescent hues and colour so much admired in the
wings of Lepidoptera: as soon as death takes place the pigment
shrivels up, leaving certain interspaces, which, when viewed above
transverse or irregular markings in the basement membrane, height-
ened by an oblique pencil of light, produce false appearances of “ rows
of beads.” The beautiful drawings sent with Dr. Maddox’s paper
show this to be the explanation of the structure of scales, while his
photographs, and also those of Dr. Woodward, prove that pseudo-beads
can as easily be produced by artificial means.

Mr. Slack said, that Mr. Hoge’s experiments on Lepidopterous
scales showed that their structure was analogous to that of the feathers
of birds. He had noticed the bulbs described by Mr. Hogg, and he
apprehended that the pigment matter was either conveyed through
the quill or by exudation from the membrane; and as it shrunk it
tended to divide into portions more or less beaded. Mr. Hoge’s
experiments seemed to him to lead to conclusions which he (Mr.
Slack) had previously ventured to bring before the Society.

A short communication was also read from Dr. Woodward, en-
titled, “‘ Additional Observations concerning the Podura Scale.”

Votes of thanks to Drs. Maddox and Woodward were then given.

Mr. Lowne read a paper “On the so-called Suckers of Dytiscus
and the Pulvilli of Insects.”

Dr. Braithwaite said, the sucker of the Dytiscus was one of the
stock objects of a microscopical cabinet, and the functions it had been
supposed to perform had been copied from book to book, without any
test being applied as te the correctness of the descriptions. He had
no doubt that Mr. Lowne had that evening explained the true func-
tions, and he believed the explanation would carry conviction to the
minds of all who had heard it. He proposed that a vote of thanks
should be given to Mr. Lowne.

280 PROCEEDINGS OF SOCIETIES.

Dr. Lawson inquired whether Mr. Lowne had found these suckers
on the female as well as the male insect.

Mr. Lowne said he had found them only on the male, and that
they were chiefly used for purposes of copulation. Sometimes the
glue they contained became so hard by drying during copulation that
the suckers were left behind by the insects, and in other cases cica-
trices were produced by the hardened glue.

Mr. Slack thought that Mr. Lowne’s hydrostatics should be ac-
cepted with some limitation; and he explained that it was theoreti-
cally possible to have a film of water so thin that the capillary at-
traction between two pieces of glass would completely counteract the
atmospheric pressure.

Mr. Lowne said, the principle he contended for was that two
bodies would be kept together under the conditions mentioned by him
by the attraction of cohesion and not of atmospheric pressure.

A vote of thanks was then giver. to Mr. Lowne; and the meeting
adjourned until the 7th of June.

Scientific Evening.

On the 10th May the Society held a scientific meeting for the
purpose of examining new or remarkable objects and apparatus,
and conversing thereupon. To avoid crowding, the admission was
restricted to Fellows, and to a very few visitors contributing to the
exhibition. About 150 persons attended, and from the subjoined list
of the principal objects displayed, it will be seen that matters of great
scientific interest were brought forward, and those present were much
gratified by the opportunity of viewing them, and obtaining informa-
tion as to the latest results. It was especially satisfactory to find tbe
arrangements thoroughly appreciated by Fellows residing in the
country, several of whom came from great distances.

The Society exhibited two of the most recent instrumental dona-
tions,—a very curious reflecting microscope by Cuthbertson, the gift
of Dr. Miller, and an elaborate microscope by Chevallier, on Amici’s
plan, presented by Sir J. Sebright.

Mr. Stephenson’s new binocular, in two forms, one having the
stage horizontal and the tubes sloping at an angle convenient to the
observer, and the other having the prisms inserted in the cell of the
objective and fitted to an ordinary instrument by an adapter, attracted
special attention, as did the immersion lenses by English and Con-
tinental makers.

Mr. J. W. Stephenson: The new binocular microscope, with safety
stage and 1th objective ; Stephenson’s erecting binocular 2-inch object-
glass, protected by a glass tube, forming a cap with thin glass end
plunged in sea water. Living Terebella and Balanus.

Dr. Millar: A slide of very rare Polycystine under Stephenson’s
erecting binocular microscope. :

Mr. 8. J. McIntire: Cheyletus eruditus, alive; Podura scale, Seira
Buskii.

Mr. Delferier: Nav. rhombvides, &e., with Powell and Lealand’s

new immersion }th.

PROCEEDINGS OF SOCIETIES. 281

Mr. Curties: Podura scale illuminated as an opaque object by
Wenham’s truncated lens and paraboloid, with a =, objective of
Gundlach.*

Dr. Braithwaite : Marchantia-like prothallium of Sphagnum cym-
bifolium, showing how it differs from the true mosses.

Dr. Gray: Section of horse’s hoof, showing the papillae.

Mr. G. H. Makins: Crystallized gold, silver, &e.

Mr. E. Richards: Apparatus for the more scientific working with
Darker’s selenites.

Mr. E. Wheeler: Aulocodiscus Kittonti, &e.

Messrs. Powell and Lealand: Amphipleura pellucida and N.
rhomboides, shown with new +),th inch objectives ; and Podura scale
shown under a }th inch with a new adjustment for correcting the
colour with different thicknesses of covering glass.

Mr. Hailes: Some slides of Foraminifera, from the ‘Norna’
expedition.

Mr. Fielding exhibited for Mr. Marshall Hall a fine specimen of
the new sponge, Pheronema Grayii, and slides of the spicules.

Messrs. Ross : Some beautiful injected preparations, and their new
immersion glasses.

Mr. Walter W. Reeves: ‘Glochidium,’ the embryo state of
Anodonta Cygnea, the large fresh-water mussel.

Mr. Blankley: New portable microscope, with fine adjustment,
and sufficient rack for a 5-inch object-glass.

Mr. How: A new lamp.

Mr. Norman: A portable cabinet to hold 141 slides in the space
of 7 inches by 5 inches.

Mr. Browning exhibited a series of diffraction spectra of magne-
sium, aluminium, and other metals, the metals being burnt by a
powerful induction coil, with a new spark condenser, the grating being
a series of fine lines, 6480 to the English inch, exquisitely ruled by
Mr. Lewis Rutherford, of New York.

Mr. Browning also exhibited one of his improved micro-spectro-
scopes, with bright line micrometer, and showed in this instrument
the absorption bands in the spectra of the following substances,—chal-
colite, salt of didymium, uranus oxide, &c., &e.

Dr. Pigott exhibited the false images and distortions of a gas
flame produced by what has been considered a fine 1th objective, and
at a later period Plewrosigma formosum, seen with a 4 inch by Wray,
brought by his aplanatic searcher to a power of 1200 linear, with
excellent definition. It was found impossible to show this properly
while the floor was in vibration from persons walking in the vicinity.

Mr. Fitzgerald: Crystals of silver formed by electric decomposi-
tion of a silver salt under the microscope. :

Mr. Ladd: His new arrangement, adapted to ordinary microscopes,
for displaying the polarizing effects of double axial crystals, the field
wide enough to take in both axes of sugar.

Mr. Slack: A series of crystals, sulphate of copper, salicine, hip-
puric acid, chlorate of potash, &c., obtained from solutions containing

* See ‘M. M. J.,’ No. VIL., p. 25.

282 PROCEEDINGS OF SOCIETIES.

colloid silica, which modifies the ordinary forms, and affords fine effects
with the polariscope.

Messrs. Beck and Beck: The Podura scale, shown under their
new +/;th immersion object-glass. It was found that by a very slight
change of focus one of Dr. Pigott’s series of beads was clearly dis-

layed.
= Wr. Suffolk: Splinter of lucifer match, ,4,ths objective. Parabolic
Lieberkihn.

Mr. C. J. Fox: A figure produced by grinding selenite, and pola-
rizing apparatus rotating by clockwork.

Mr. Hogg: Merz’s immersion ,th, exhibiting its penetration
through thick covering glass, and its capability of being used with
Wenham’s binocular, with equal iJlumination of field three-fourths
of each field space. Volvox and Closterium were shown in a cell
deep enough to allow the rolling motion of the former, and yet not
preventing the circulation in the latter, being displayed. Also scales
of azure blue, attached to membrane by bulbous extremity, and
torrefied Podura.

Mr. Charles Stewart: Injected bile ducts, showing terminal
plexuses, from the liver of a cat; and larva case of some Trichopterous
insect, interesting for so closely resembling a Hydra as to be readily
taken for that animal. It is found in great abundance in Devonshire
streams.

Mr. B. T. Lowne: Injected tissues from the frog, and dissections
from the nervous system of the fly.

Donations to the Library and Cabinet from April 5th to May 8rd,
1871:—

From

Land and Water. Weekly ae A der ka sey tele Sen ACRE Inet
Society of Arts Journal. Weekly PANGAN AS 465. SIA
Nature. Weekly . ie on ae ee lOntOms
Athenzeum, Weekly : ae) Spiel” oe - Sone ee epeeoe
Journal of the Quekett Club, No. 14 tip Aste GES
Journal of the London Institution, No. 5.. Institution.
Mikrographische Beitrage von Alexander Stuart in

Odessa... Author,
Uber den Bau der Gregarit inen ; ‘yon Alexander Stuart

in Odessa... Author.
Verhandlungen der Kaiserlich-koniglichen Zoologisch-

Botanischen Gesellschaft, 1870.
Klimatologische Notizen iiber den Winter in Hochgeberge.

By Arthur W. Waters, F.R.S. .. oo ee Antone
Traité du Microscope. Par Chas. Robin, “1871+. 44 Aare
Report on Barracks and Hospitals in America... Surgeon-General, U.S.
100 Slides of Vegetable Fibres .... os, oo, on » WellnuSerpouam enn

The Rev. W. H. Dallinger and Baganth Thompson Lowne, Esq.,
M.R.C.S., were elected Fellows of the Society.

Watter W. Reeves,
Assist,-Secretary.

(aes

INDEX TO VOLUME V.

+ ——

iN.

APROCONISCOPE, or Air-dust Collecting
Apparatus, Observations on the Use
of the. By Dr. Manpox, 45.

Aurens, C. D., on a New Form of
Binocular Eye-piece and Binocular
Microscope for High Powers, 113.

American Association, Microscopy at
the, 273.

ARNOLD, Herr J., on the Regeneration
of Epithelial Formations, 232.

Atax, a Species of, Parasitic on Fresh-
water Mussels. By M. Emin BrssEzs,
184.

iB:

Baceuuir, Signor, What is the Use of
the Spleen? 233.

Barnard, F. A., on a New Form of

Binocular Microscope, 32.

BEL, James, F.C.S., on the Microsco-
pical Examination of Water for
Domestic Use, 163.

Bessets, M. Emit, on a Species of Atax
Parasitic on Fresh-water Mussels,
184.

Bibliography, 44, 200, 244.

BickNELL, Mr. E., on Diatoms thrown
up by the Sea, 34.

Blood-stains, 84.

Brachiopods, Are they Annelids? By
Mr. Epw. S. Morss, 135.

Bratpwoop, Dr. P. M., on Cancer of
the Kidneys in Children, 186.

Bristle-tails and Spring-tails, the Ovi-
positor of. By Mr. L. S. Packarp,
jun., 231.

(Oy

Cancer of the Lymphatics, Microsco-
pical Appearances of. By Dr. Wurr-
ALL, 31.

CarpPENTER, Dr. P. P., on the Struc-
ture of Chitons, 273.

Carter, Mr. H. J., Observations of
Pachytragous Sponges, 185.

CASTRACANE, Count, on the Magnifying
Power of the Microscope, 173.

Cells, on. By M. Movcuet, H.F.R.MLS.,
276.

Chitons, on the Structure of. By Dr.
P. P. CARPENTER, 273

Coals, Spore-cases in, 275.

Colloid Silica, on the Employment of,
in the Preparation of Crystals for
the Polariscope. By H. J. Suack,
F.G.S., 50.

——, on Crystalline Forms Modi-
fied by. By H.J. Stack, F.R.S., 115.

Compressor, a Clinical. By Dr. Warp, 35.

Consumption, Detection of, with the
Microscope. By Dr. RicHarpson, 30.

Corg, Professor E. D., on the Metamor-
phoses of Siredon Mexicanus, 133

CORRESPONDENCE :—

BaRNakD, F. A. P., 123.
BIcKNELL, Epw1y, 121, 277.
Brees, CHARLES, 237,
Brakey, 8S. Lesiie, 187.
CHANTRELL, G. F., 236.
Curtis, Jostan, 123.

Gipss, WALcorT, 122.
Knicut, R. D., 190
McIntirz, 8S. J., 38.
Movcuet, M., 276.

Reeves, W. W., 193.
Roystron-Picort, 138.
Sack, H. J., 193.

TERBECQ, CHEV®. F. H. Dr, 276.
Wake, C. STANILAND, 139.

Cunirr, CHArLEs, C.E., on the Winter
Habits of the Rotatoria, 168.

, on Linear Projection in its Appli-
cation to the Delineation of Objects
under Microscopie Observation, 205.

C. S. on the Motion of Microscopic
Granules, 81.

Cut Lines in Glass, the Optical Ap-
pearances of. By H. J. Stack, 213.

D.

Datt, W. H., on Striated Muscular
Fibre in Gasteropoda, 134.

Diatomacee, &c., on Bleaching. By
Dr. Mappox, 274.

or Infusorial Earths.
A. M. Epwarps, 234.

Diatom-prism, on the Mounting of the.
By F. W. Grirrin, 24.

Diatoms, on Mounting.
H. De TERBECQ, 276.

— thrown up by the Sea.
EK. BIcKNELL, 34.

Dytiscus, on the so-called Suckers of,
and the Pulvilli of Insects. By B.
T. Lowne, M.R.C.S., 267.

By Prof.

By Chev". F.
By Mr.

284

E.

Ear, Fungi in the, 230.

Epwarps, Prof. A. M., on the Micro-
scopical Examination of Two Mine-
rals, 226.

on Fresh-water Diatomaceze or
Infusorial Earths, 234.

Eozoon, another District for, 234.

Epithelial Formations, the Regenera-
tion of. By Herr J. ARNoLD, 232.

Exhibition, the Microscope at the, 85.

Eyesight and the Microscope, 275.

iy

Fat, the Origin and Nature of. By
Herr Toupt, 229.

Fluorescence v, Pseudo-Dichroism, Note
on. By the late Rev. J. B. Reaves,
F.R.S., 1.

Foraminifera, the Range in time of the.
By Prof. T. R. Joyzs, F.G.S., 233.

G

Gasteropoda, Striated Muscular Fibre
in. By W. H. Dat, 134.

Glass, Cut Lines in, on the Optical
Appearances of. By H.J. Siack, 213.

Grare, Von, the Library of the late
Professor, 234.

Granules, Microscopic, the Motion of.
By C.§., 81.

Graptolites, a new Genus of.
J. Hopkinson, 187.

Grirrin, F. W., on the Mounting of
the Diatom-prism, 24.

Gulf Stream, Rocks and Dredgings
from the, 235.

By Mr.

131

Hupson, ©. T., on Pterodina valvata,
a new Species, 20.

I.

Immersion Lenses, on the History, Re-
fractions, Definition, and Powers of.
By Dr. Roysron-Picorr, M.A., 65.

Infusoria and Sponges, 133.

Insects, Notes on the Minute Structure
of the Scales of Certain. By S. J.
McIntirp, 3.

— , the Abdominal Antenne of, are
Sense Organs. By A. S. Packarp,
jun., 81.

, Parthenogenesis in the Pupz of,

232.

, the Pulvilli of, and the so-called
Suckers of Dytiscus, 267.

——, the Embryology of. By Mr. A.
S. PackaRD, jun., 272.

INDEX.

J.

Jounson, Mrrcaurs, a few Experiments
bearing on Spontaneous Generation,
178.

on the Transmutation of Form in
Certain Protozoa, 222.

Jones, Professor Rupert, on the Range
in Time of the Foraminifera, 233.

K.

Kidneys, Cancer of, in Children, By
Dr. P. M. Braipwoop, 186.

iby

Lamp, a New Microscope.
37, 84.

Ler, Mr. Henry, a New Locality for
Trocheta subviridis, 36.

Lepidocyrtus, the Scales of. By 8S. J.
McIntire, 38.

Lepidoptera, Scales of some of the,
Remarks on the General and Par-
ticular Construction, By R. L.
Manppox, M.D., 247.

Lewis, T. R., a Report on the Micro.
scopic Objects found in Cholera Eva-
cuations, 128.

Light, Monochromatic, 235.

Limulus Polyphemus, Embryology of.
By Dr. A. 8. Packarp, jun., 31.

Linear Projection considered in its Ap-
plication to the Delineation of Objects
under Microscopie Observation. By
Cuares Cusirt, C.E., 205.

Linnezus, the Originator of the Hypo-
thesis of the Derivation of Species,
136.

Lowne, B. T., on the Anatomy of the
Round - worm (Ascaris lumbricoides),
55.

Brownie,

on the so-called Suckers of
Dytiscus and the Pulvilli of Insects,
267.

Lungs, the Lymphaties of the, 229.

M.

Manppox, Dr., Observations on the Use
of the Aéroconiscope, or <Air-dust
Collecting Apparatus, 45.

— on Bleaching Diatomacex, &c.,
274.

— R. L., M.D., Remarks on the
General and Particular Construction
of the Seales of some of the Lepi-
doptera, as bearing on the Structure
of the ‘‘ Test-Scale,” 247.

Mappox’s Photographs of the Podura
Scale, 33.

INDEX,

McIntirg, 8. J., Notes on the Minute
Structure of the Scales of Certain
Insects, 3.

on the Scales of Lepidocyrtus, 38.

Microscope, the Magnifying Power of.
By Count Casrracane, 173.

, a New Form of Binocular. By

F, A. BaRnarD, 32.

for High Powers, on a New
Form of Binocular Hye-piece and
Binocular. By C. D. Aurens, 113.

——, Gundlach’s, 36.

Microscopes, on the Illumination of
Binocular. By Dr. R. H. Warp,

Je

Microscopical Society, Extra Meeting
of the Royal, 275.

Microscopy at the American Associ-
ation, 273.

, the American Journal of, 84.

Micro-Telescope, A. By Dr. Curtis,

ov.

Minerals, Microscopical Examination
of Two. By Prof. A. M. Epwarps,
226.

Morsr, Mr. Epwarp §., Are the Bra-
chiopods Annelids? 135.

Movcurt, M., H.F.R.MS., on Cells,
276.

N.

New Books, witH Suort Notices :—

A Report on the Microscopie Objects
found in Cholera Evacuations. By
Timotuy Ricuarvs Lewis, M.B.,
128.

Microscopic Objects Figured and
Described. By Joun H. Martin,
182.

The Natural History of the British
Diatomacese. By ArtHur S. Don-
Kin, M.D., 182.

Nobert’s Test-plate, Photographs of.

By Dr. Woopwanp, 34.

— Nineteenth Band, 85.
Nineteenth Band and its Ob-
servers. By Cuaries Sropper, 118.

O.

Object-glasses and their Definition. By
F. H. Wenuay, C.E., 16, 117, 216.
Objectives, on Mounting very Low.

By Mr. Totes, 35.
——, Committee for Testing, 275.
Organisms, on some Recent Investiga-
tions into Minute. By H. J. Siacx,
G3) 99:

285

Vee

Packarp, Dr, A. §., jun., on the Em-
bryology of Limulus Polyphemus, 31.

, the Abdominal Antenne of In-
sects are Sense Organs, 81.

—— on Insects in Deep Salt-water,
133.

—— oa the Embryology of Insects,
272.

, Mr. L. §., on the Ovipositor of
the Bristle-tails and Spring-tails,
231,

Parritt, Mr. Epwarp, on the Struc-
ture of Crustacean Shells, 83.

Parker, W. Krrcuen, F.R.S., on the
Mode of Working-out the Morpho-
logy of the Skull, 201.

Parthenogenesis in the Pup of In-
sects, 232.

Purures, J. A., on the Microscopical
Characters of Certain Rocks, 183.
Photo-micrographs for the Stereo-

scope, 231.
Phycocyan, the Development of. By
T. C. Wart, M.R.CS., &., 83.
Podura Scale, Photographs of. By Dr.
Mavppox, 33.
, Additional Observations
concerning the. By Dr. J. J. Woop-
WARD, U. 8. Army, 245.
and certain other Test-
objects, on the Structure of, and their
Representation by Photography. By
Lieut.-Colonel Dr, J. J. Woopwarp,
U.S. Army, 245.
PROCEEDINGS OF SOCIETIES :—
Brighton and Sussex Natural History
Society, 43, 142, 198, 241.
Bristol Microscopical Society, 40.
Croydon Microscopical Society, 137.
Liverpool Microscopical Society, 40.
Reading Microscopical Society, 44,
146.
Royal Microscopical Society, 39, 86,
140, 194, 237, 277, 280.
Tunbridge Wells Microscopical So-
ciety, 40.
Prototaxites Logani, a Colossal Fossil
Seaweed, 274.
Protozoa, Transmutation of Form in
Certain. By Mercatre Jounson, 222.
Pterodina valvata, on. By CO. T.
Hupson, LL.D., 25.

R.

Reape, Rev. J. B., F.R.S., Note on
Fluorescence v, Pseudo-Dichroism, 1.

Ricuarpson, Dr. J. G., on the Detec-
tion of Consumption with the Micro-
scope, 30.

286

Rocks, the Microscopical Characters of
Certain. By J. A. Purmuirs, F.CS.,
183.

Rotatoria, on the Winter Habits of the.
By Cuarues Cusirt, C.E., 168.

Round-worm (Ascaris /umbricoides), on
the Anatomy of. By B. T. Lownz,
M.R.C.S., 55.

Royal Microscopical Society, the An-
nual Address, 89.

——, Obituary Notices, 92.

——, Extra Meeting of the, 275.

Royston-Pigort, Dr., on the History,
Refractions, Definitions, and Powers
of Immersion Lenses, 69.

on Microscopical Appliances, 79.

— on a Searcher for Aplanatic
Images applied to Microscopes, and
its Effects in increasing Power aud
Improving Definition, 129.

Ss.

Salt-water, Insects in Deep. By A.S.
PaAcKARD, jun., 133.

Scales of Insects, Notes on the Minute
Structure of. By S. J. McInrirg, 3.

Searcher, the Aplanatic. By Dr.
Royston-Picorr, M.A., 129.

Seaweed Colossal Fossil (Prototaxites
Logani), 274.

Shells, on the Structure of Crustacean.
By Mr. Epwarp Parrirt, 83.

Silica Films, Cracks in. By H. J.
Sack, 14.

Siredon Mexicanus, Metamorphoses of.
By Prof. E. D. Corr, 133.

Skull, on the Mode of Working-out the
Morphology of. By W. KircHEen
Parker, F.R.S., 201.

Siack, H. J., F.G.S., &., on an Optical
Illusion Slide: Cracks in Silica Films,
14.

— on the Employment of Colloid
Silica in the Preparation of Crystals
for the Polariscope, 50.

on some Recent Investigations

into Minute Organisms, 99.

, on Crystalline Forms Modified by

Colloid Silica, 115.

on the Optical Appearances of
Cut Lines in Glass, 213.

Slide, on an Optical Illusion.
J. SLACK, 14.

Soirée, the Croydon Microscopical
Club’s, 37.

By H.

INDEX.

Spleen: What is the Use of the? By
Signor Bace tt, 233.

Sponges, Pachytragous, Observations
of. By Mr. H. J. Carrer, F.R.S., 185.

Spontaneous Generation, a few Expe-
riments bearing on, By Merrca.re
JouNson, 178.

Stains, Blood, 84.

Bisroere Photo-micrographs for the,

31.

SroppER, CHARLES, on Nobert’s Nine-

teenth Band and its Observers, 118.

A I

Terseca, Chevalier F'. H. pr, on Mount-
ing Diatoms, 276.

Test Scale, Lepidocyrtus curvicollis, Re-
marks on the General and Particular
Construction of the Scales of some of
the Lepidoptera, as bearing on the
Structure of the. By R. L. Mappox,
M.D., 247. —

Toxp, Herr, on the Origin and Nature
of Fat, 229,

Totes, Mr., on Mounting very Low
Objectives, 35.

Trocheta subviridis, a New Locality
for. By Mr. Henry Lez, 36.

We

Warp, Dr. R. H., on the Illumination
of Binocular Microscopes, 33.

, Dr., on a Clinical Compressor, 35.

Water, the Microscopical Examination
of, for Domestic Use. By JAmes
Bett, F.C.8., 163.

Wenuaw, F. H., C.E., Object-glasses
and their Definition, 16, 117, 216.
Waray, Dr., on the Microscopical
Appearances of Cancer of the Lym-

phaties, 31,

Wurrt, T. C., on the Development of
Phycocyan, 53.

Woopwarp, Dr., Photographs of No-
bert’s Test-plate, 34.

——,, Lieut.-Col., on the Structure of
the Podura Seale and other Test-
objects, 149.

—,, Col., Approval of his Efforts, 232.

Dr. J. J., U. S. Army, Addi-

tional Observations concerning the

Podura Scale, 245.

Z.
Zoology, the History of, 235.

END OF VOLUME V. f }

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

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