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THE MONTHLY
MICGROSCOPICAL JOURNAL:

TRANSACTIONS

OF THE

ROYAL MICROSCOPICAL SOCIETY,
RECORD OF HISTOLOGICAL RESEARCH

AT HOME AND ABROAD.

EDITED BY

HENRY LAWSON, M.D., M.R.C.P., F.R.MLS.,
Assistant Physician to, and Lecturer on Physiology in, St. Mary’s Hospital.

VOLUME XV.
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REW YORK
BOTANICAL

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HARDWICKE anv BOGUE, 192, PICCADILLY, W.

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THE

MONTHLY MICROSCOPICAL JOURNAL.

JANUARY 1, 1876.

I.—The Absorptive Glands of Carnivorous Plants.

By Aurrep W. Bennett, M.A., B.Sc., F.L.S., Lecturer on Botany
at St. Thomas’s Hospital.

(Read before the Royat Microscorrcan Society, December 1, 1875.)
Prats CXXVI.

TuoseE plants which possess the peculiar power of absorbing and
digesting nitrogenous substances presented to their leaves, have from
time to time engaged the attention of vegetable physiologists. Among
the more important papers on the subject may be mentioned those by
Gronland and Trécul, in the ‘ Annales des Sciences Naturelles’ for
1855; Nitschke, in the ‘ Botanische Zeitung’ for 1860-61; Warming,
in the Proceedings of the ‘Société d'Histoire Naturelle de Copen-
hague’ for 1873; and, above all, Darwin’s work on Insectivorous
Plants, published during the present year. These publications deal
chiefly with the insectivorous plants belonging to the genera Dro-
sera, Pinguicula, Dionxa, and Utricularia ; the “ pitcher-plants,”
Nepenthes, Sarracenia, Darlingtonia, and Cephalotus, not having at
present received so large a share of attention. As might naturally
be expected at first, observation has been up to the present time
chiefly directed to the remarkable phenomena connected with the
capture and apparent digestion of the living animals which in the
natural state are chiefly devoured by these plants ; while but little
investigation has been applied to the discovery of internal organs by
the aid of which absorption is effected ; and the assumed absence of
any such organs has indeed been brought forward as an argument

EXPLANATION OF PLATE CXXVI.

Fias. 1-5.—Drosera rotundifolia: gl, absorptive gland in various stages of deve-
lopment; pa, cellular papille; pr, processes from papille; st,
stoma.

6-8.—Pinguicula vulgaris ; gl, absorptive gland; st, stoma. Fig. 8 represents
a lateral view of a gland projecting slightly above the surface.

Fia. 9.—Callitriche verna ; gl, absorptive gland; st, stoma.

* All from nature, and x 250 diam.
VOL. XV. B

”

2 Trans ‘etions of the Royal Microscopical Society.

against the possibility of absorption by the leaves. In the case of
Dionxa, Darwin gives a very brief description of minute glands of a
reddish-purple colour which cover the upper side of the leaf, and
which he states to have the power of absorption. But in order to
find an adequate description of these bodies we must go back nearly
thirty years, when Dr. Lindley gave accurate descriptions and
figures of them in his ‘ Ladies’ Botany,’ published in 1834, and, in
the following words, showed a wonderful insight into their probable
function :—“ From the cuticle of the upper surface of the leaf of
Dionea there spring at short intervals little red glands, which grow
from minute green oval spaces, composed of two parallel green cells
and resembling stomates. They are firm fleshy bodies resembling
little convex buttons, and are composed of cells arranged in a circu-
lar manner round an axis consisting of two such cells stationed one
on the top of the other. I presume that these glands are analogous
to the curious hairs of Sundew, although we do not see that they
are possessed of any irritability ; but in the Sundew they arise from
a general expansion of the cuticle and not from spurious stomates.
- We moreover find upon the surface a prodigious number of red

glands, so minute as to be individually invisible to the naked eye,
and giving a red tinge to the leaf. Such glands are found nowhere
except upon the upper surface of the leaf in the neighbourhood of
the delicate seat of irritability. It is not improbable that these
glands are either in some way connected with the irritability,
although it is not they through which the shock is first communi-
cated to the leaf, or, as Mr. Curtis supposes, are intended to absorb
the nutriment afforded to the leaf by the decay of the insects en-
trapped in it.” Similar bodies are also known to exist in Nepenthes ;
and were likewise described by Dr. Lindley, in his ‘ Introduction to
Botany,’ edition 1848, as stomates of a peculiar construction in
contact with an internal deep brownish-red gland.

My own observations have been entirely confined to the two
most readily obtainable of our English carnivorous plants, Drosera
rotundifolia and Pinguicula vulgaris; having paid considerable
attention to the structure of the leaves in these two species during
my summer holidays for the last three years. In the summer of
1873, while staying in Westmoreland, I first observed and drew
certain bodies imbedded in the leaf of Drosera which it struck me
must be connected with the processes of absorption and digestion,
although I could find no record of them by any previous observer.
Hearing shortly afterwards that Mr. Darwin was likely soon to
bring before the public his store of long-accumulating investigations
on these plats, I refrained from publishing my observations. When,
however, Darwin’s ‘ Insectivorous Plants’ came out, in the spring
of 1875, I found no record of the existence of these bodies, notwith-
standing the otherwise full and accurate description of the structure

Absorptive Glands of Carnivorous Plants. By A. W. Bennett. 3

of the leaves in both genera.* I therefore sent to the ‘ Popular
Science Review’ for October in that year, a brief and somewhat
inadequate description and figure, which I now propose to give
somewhat more in detail, in the hope of throwing some additional
light on the processes with which they are apparently connected.

If a careful section is made of the leaf of Drosera rotundifolia,
there will be found a number of bodies which might at first sight
be easily mistaken for stomata, but which are of essentially different
structure. In Fig. 1, Pl. XXVI., one of these bodies is represented
at gl. They are, in their first origin, not superficial, but appear
to arise immediately beneath the cuticle chiefly, or perhaps exclu-
sively of the upper surface ; in one case I found one imbedded in
the tissue immediately beneath a “ tentacle” or glandular filament.
They consist of two nearly hemispherical cells, filled with a yellowish-
brown apparently protoplasmic substance, and form together a nearly
spherical body, of which the longest diameter is about *00075 (<0o0)
inch. They are more nearly circular and somewhat smaller than
the stomata, one pf which (st) is shown in the drawing. In each of
the hemispheres is a darker nucleus-like spot, and each is surrounded
by a thin-walled cell containing chlorophyll-grains, much smaller
than the ordinary cells of the mesophyll of the leaf, and which seems
subsequently to disappear. From these hemispherical bodies are
developed two papille, successive stages of which are shown by
pa in Figs. 2-5, with thin transparent walls, and containing
grains of chlorophyll. These papillae sometimes rise above the sur-
face of the leaf or of the filaments of the “tentacles.” The hairs
or papillee which result from these glands have been described and
figured by Meyen,} Trécul,t and Nitschke,§ and are referred to in
Darwin’s work, p. 8; but their origin from the glands does not
appear to have been observed, and they are described as being en-
tirely of an epidermal nature. In the gland drawn in Fig. 5, an
indication is apparent of a quadripartite division ; and there are
also a couple of minute processes (pr), one from each hemisphere,
which I have also observed in other instances springing either from
the glands themselves or the cellular papille; one such process is
again represented in Fig. 4. To the bodies now described I
gave, in the article already referred to,|| the provisional name of °
“oanglia,’ which term however I propose now to replace by
“ absorptive glands,” in allusion to their supposed function, and in
order to distinguish them from the secretive “ glands,” as they are
termed by Darwin, which form the apices of the “ tentacles.”

* T have since had the pleasure of showing my preparations to Mr. Darwin
who tells me that these bodies have not hitherto engaged his attention.

+ ‘Die Secretions-Organe der Pflanzen,’ 1837.

+ ‘Annales des Sciences Naturelles, Botanique,’ 4 series, vol. iii. p. 308.

§ ‘Botanische Zeitung,’ 1861, p. 235.

| ‘ Popular Science Review,’ 1875, p. 358.

B 2

1 Transactions of the Royal Microscopical Society.

The leaf of Pinguicula possesses similar bodies, but somewhat
different in structure. Fig. 6, gl represents their ordinary form.
They are considerably larger than in Drosera, nearly circular (but
apparently flat rather than spherical), and about -0014 inch in
diameter, divided into four quarters, filled with a similar yellowish-
brown protoplasmic substance, and each of the quarters distinctly
enclosed (in the young state of the gland) in a transparent cell-
wall. A circular transparent wall encloses the whole; but there
are no enveloping cells similar to those delineated in Fig. 1; nor
have I ever observed any papillee or other processes proceeding from
them. They sometimes, however, form slight elevations above the
surface, as seen in Fig. 8. At a later period, as shown in Fig. 7,
the number of divisions increases, sometimes amounting to as
many as eight, and the separating walls of cellulose nearly or quite
disappear. Astoma is here again represented, to show the com-
parative size.

Before commencing my investigations of Drosera, my attention
had been directed to the occurrence of bodies of a similar nature in
a corresponding position in the floating leaves of a common little
water-plant, Callitriche verna, i.e. beneath the cuticle of the upper
surface.* These bodies were described as long ago as 1850,1 by
the late Dr. Lankester, who, however, ascribed no special function
to them. The glands themselves are more minute eyen than in
Drosera, about *0005 inch in diameter, nearly spherical, and dis-
tinctly quadripartite, each division being again filled with a yellowish-
brown substance. These are surrounded by a circular border or
cell-wall of cellulose, also divided into four, and less opaquely
filled up with a similar substance. ‘hey are entirely concealed
beneath the surface,‘ and do not appear to develop into papille.
One is represented at Fig. 9, together with a stoma. From the
extreme similarity of these bodies to those already described in
Drosera and Pinguicula, the idea suggests itself whether Calli-
triche is not also carnivorous.

The question now arises, What is the purpose of these organs,
which present so similar a structure in the plants now described ? Is
it connected with the absorption and digestion of nitrogenous food
. presented to the leaves? A direct answer to this question is at-
tended with almost insurmountable difficulties. Unlike the secretive
glands of Drosera and Pinguicula, they are buried in the tissue of
the leaf, and it is impossible to place them under the microscope
without altogether destroying the surrounding tissue. It is cer-
tainly remarkable that bodies more or less analogous to these are
present in every plant which has been, down to the present time,

* [had formerly, but erroneously (/. c., p. 358, footnote), supposed the “rosulate”

appearance of the leaves to be due to these bodies.
t ‘Proc. Linn. Soc.,’ ii., 1848-55, pp. 94, 95.

Absorptive Glands of Carnivorous Plants. By A. W. Bennett. 5

certainly included under the category of carnivorous. I have already
alluded to their existence in Nepenthes and Dionwa. The bodies
described by Darwin under the name of “ quadrifids” in the bladders
of Utricularia bear a strong resemblance to the absorptive glands
of Drosera after the development of the papille ; and the drawing,
Fig. 30, at p. 448, of the similar bodies in Genlisea, a Brazilian
plant nearly allied to Utricularia, exhibits a still more striking
resemblance. No less remarkable is their absence from all plants
which do not possess this power ; the only exception to this, as far
as I am aware, being in the case of Callitriche. I have closely
examined the leaves of the British plant supposed to have the nearest
affinity to Drosera, Parnassia palustris, without detecting the
least trace of them. It is to be hoped that future researches will
throw more light on these interesting objects.

( 6

I1.—Reproduction in the Mushroom Tribe.
By Worrtueton G. Surra, F.LS.
(Coprinus radiatus, Fr.)

For the purposes of minute research into the vital phenomena
of the Mushroom tribe, Coprinus radiatus, Fr., possesses many
advantages over the other species of the large order to which it
belongs. The first great advantage peculiar to C. radiatus is that
it grows readily and abundantly on dungheaps from April to
December, and it comes up equally well in town and country. The
second point in its favour is that it is so small and transparent that
every part can be quickly examined, and an entire plant kept under
the covering glass of the microscope. The third advantage found
in C. radiatus rests in the fact of its whole life being so exceed- —
ingly short, that its entire vital functions are performed in a few
days. Having these points in view, I have, during the whole of the
present summer and autumn, kept up a large bed of fresh horse-
dung in my garden, and from this bed I have narrowly watched
the growth of many generations of the plant I am about to
describe.

A complaint is often made by persons unused to the micro-
scope, and to the appearances of objects as seen by its aid, that it
is impossible to see the real objects as they are represented in draw-
ings. Toa certain extent this is borne out by facts, for a drawing
is never meant to represent what may be accidentally seen at one
sitting, but is designed as a summing-up of all that has been seen
during many hundreds of sittings. Anyone looking for the first
time through a good telescope at Jupiter's moons, Saturn’s ring, or
the planet Mars, might be a little disappointed in the apparent
smallness and lack of strongly marked outlines in the objects seen ;
but this does not detract from the correctness of astronomical
diagrams, which are only matured after many patient observations.
No one expects to see the solar system as shown in a model, or the
country as seen on a map.

It may reasonably be premised that the facts observed in con-
nection with the life history of Coprinus radiatus will more or less
apply to all the other species belonging to the Mushroom tribe ;
but it would be impossible to make the observations here recorded
on the more fleshy species, because, instead of days, these latter
plants take months to mature. In C. radiatus generation after
generation keeps springing up in almost daily succession, but in the
more fleshy species, exclusive of Coprinus and Bolbitius, I am con-
vinced there is, as a rule, but one generation in the year. The
common Agarics of the autumn spring up from the mycelium
formed during the fall of the previous year, and this mycelium has

Reproduction in the Mushroom Tribe. By W.G. Smith. 7

rested in the ground for twelve months. In digging up old pasture
ground, or the dead leaves of an autumn which has passed, myce-
hum in a resting state is invariably found. There is no such long
rest with the mycelium of Coprinus radiatus, for so long as the
weather is not too dry, too wet, or too cold, the fungus goes on per-
fecting itself day after day without ceasing. During hot, very
wet, or frosty weather the spawn lies buried, and it rests in the
warm, moist dung for short periods of time ouly.

Coprinus radiatus, Fr., is one of the dung-borne Agarics with
a cap which measures from an eighth to one-quarter of an inch in
diameter, and this filmy pileus is supported on a stem, which on an
average measures froma quarter to three-eighths of an inch or more
in height (Figs. 1 and 2, A). The whole cap is a mere transparent
film, and the fragile stem is like an atom of gossamer thread. A
breath will totally break down and collapse every part of the plant,
whilst a heavy dew or slight shower of rain will destroy a whole
colony. These minute Agarics can only be gathered with the aid of
small forceps, for if they are taken in the fingers they at once
collapse, become liquid and vanish. So little moisture does a single
specimen contain that it is lost in the moment or two consumed in
taking it for examination from the garden to the house. The
young plants may generally be seen dotted over the dung, like in
size to so many pins’ heads (Fig. 1, B), and from this, the infant
state, to maturity, the growth of the fungus is very rapid. At
seven or eight in the evening nothing but immature plants can be
seen (Fig. 1, C, D, enlarged 20 diameters) ; about eleven or twelve
a rapid growth commences, and by two or three o'clock in the
morning the full size is reached. If the morning is moist the
plants will remain in perfection till nine or ten o'clock, but if it is
dry they will not last after five or six. On shady roadsides or in
dark places the time required for growth may probably be a little
more or less, but the present observations apply to the plants as
found growing on dung in a light and open place.

To get a good view of C. radiatus it is necessary to magnify it
at least from 50 to 100 diameters; the nature of the stem and
gills can then be made out, and all the individual component cells
be clearly seen.

Mature plants are figured at E, F (Fig. 1), enlarged 10 and 20
diameters, the first showing the nature of the outer surface of
pileus, with its furrows, and the other the lower or fruiting surface,
with the nature of the gills, and the collar formed by them near
the insertion of the stem. At G is shown the relative number of
the basidia or privileged cells, which carry the naked spores, and at
H the relative number and position of other privileged cells, termed
cystidia. ‘T’o these latter bodies I shall presently refer more fully,
and they are merely adverted to here that some idea may be formed

8 Reproduction in the Mushroom Tribe. By W. G. Smith.

of their great number. At I is shown a horizontal section through
the cap of the fungus, .a short time before expansion (when the

W.C.S, AD.NAT. SC,

Fic. 1.*—Coprinus radiatus, Fy.
A, Natural size; E, Enlarged 10 diam.; other figures, 20 diam.

* The blocks haye been kindly lent by the Editor of the ‘Gardeners’ Chronicle.’

Reproduction in the Mushroom Tribe. By W.G. Smith. 9

umbrella-like top is down), to show that the hair-like stem is
hollow, and that the plant in infancy is enveloped in a complete

W.G.S. AD. NAT. SP

Fig. 2.—Coprinus radiatus, Fr.
Enlarged 50 diam.

veil or bag, the presence of which is shown by the ring of cells and
hairs which forms the circumference of the diagram.

10 Reproduction in the Mushroom Tribe. By W. G. Smith.

For a proper comprehension, however, of this minute fungus
much more than a superficial examination is necessary, and the first
thing to be done in the way of dissection is to secure a good longi-
tudinal section of the fungus from top to bottom, as shown in
Fig. 2 (J); this enlarged 35 diameters, at once shows the immense
number of cells which go to make up one of the fugitive little
plants belonging to Coprinus radiatus. By reference to the figure
it will be seen that the stratum of flesh which forms the pileus is
only six or seven cells in thickness, and the external surface is
covered with a few hairs of different sizes (the remnants of the uni-
versal veil or wrapper), some of the smaller hairs being tipped with a
gland. Another good vertical segmental section across the cap and
gills will show the appearance of the plicato-radiate outer surface
of the pileus to be caused by a series of cracks which are brought
about by the necessarily sudden expansion of the cap, which act of
expansion tears (in these positions) the component cells of the pileus
apart, Fig. 1, E, and Fig. 2, K. <A transverse section through the
fungus when in an infant state shows the commencement of these
fissures, as at Fig. 1, I, and Fig. 2, L. The gills have no trace of
a trama, the so-called trama being the cells which form the sub-
stance between the hymenium in the gills; if present this substance
would be at MM, Fig. 2; but one of the characters of the genus
Coprinus is that the gills have no distinct immediate substance in
the gills. In the plant under examination the lamelle or gills are
free from, and form a collar round the stem (Fig. 2, N), and are
only about seven cells in thickness.

Good sections down and across this stem when young will show
it (gossamer-like as it is) to be piped or hollow from top to bottom
(Fig. 2, O), and the hairs seen at the base (PP) are the torn
remains of the veil or wrapper which once held the edge of the
pileus (Q) down to the base of the stem. In this figure several
spores may be seen at the base, carried up amongst the cells of the
stem. On looking atan entire plant of C. radiatus in this way under
a low power of the microscope it appears to be formed of a few
thousands of cells only, but if these cells are now measured and
counted, which is by no means a difficult matter, it will be found
that instead of thousands it really requires millions of individual
cells to build up one of these minute plants which a breath destroys.
The smallness and lightness of one fungus is such that it requires
150 specimens to weigh a grain, or 72,000 to weigh an ounce troy.
In the type specimen of C. radiatus now figured there were
22,560,000 cells in its structure irrespective of the spores, which .
numbered about 3,200,000 more. If all these cells and spores are
only equivalent to the hundred-and-fiftieth part of a grain, it
follows that in an ounce of fungus cells there must be no less than
one billion six hundred and twenty-four thousand millions of these

Reproduction in the Mushroom Tribe. By W.G. Smith. 11

bodies, exclusive of the spores. In a large Mushroom the cells
would number hundreds of billions. Still more wonderful is the
fact that each individual cell is furnished with a spark of life,
contains water, protoplasm, and other material, and is capable of
growth and assimilation.

The purpose of this essay is to demonstrate something of the life
history of the minute but truly wonderful fungus now before us;
and with this object in view it is not only necessary to use the
higher powers of the microscope, but to patiently watch the fungus
and its changes at every hour (almost minute) of the night and day
and for several days in succession.

In the vertical section of one of the minute gills, as shown in
Fig. 8, magnified 150 diameters, the whole fruiting and reproduc-
tive surface of the fungus is seen at a glance. The nature of the
furrows in the pileus (R) is now perfectly clear, every cell being
seen in position, and the remnants of the universal veil or wrapper
are seen on the surface of pileus at 8S. Studded amongst the cells
of the upper stratum of cap may be seen various brilliant crystals
which belong to the ammonio-phosphate of magnesia, and which
erystals are taken up by the fungus from the manure on which it
grows. Many dung-borne Agarics are covered with so-called
micacéous particles, which, in many instances, doubtlessly arise
from the manure which supports the fungus. It is a matter of
considerable difficulty to get a section like this, for if attempted
clumsily no result will follow beyond a slight discoloration of the
edge of the lancet; it is necessary to take the slice at the exact
moment of maturity, and evén then it requires the perfection of
dexterity to cut the fungus properly, as the plant is sticky in all its
parts. A fragment of the fruiting surface of a gill is shown at T.

To understand the vital phenomena of C. radiatus it is neces-
sary to comprehend the meaning of the bodies seen in Figs. 3
and 4. The whole fungus is built up of cells, which run parallel
with each other (and at maturity are very long) in the stem
(Fig. 2), and which spread laterally, and then hecome more or less
spherical in the pileus. When these cells reach the gills or fruit-
bearing surface (hymenium, U U), a certain differentiation takes
place in their functions. The majority of the cells remain simple,
but certain other cells which are spread over the gills with the
greatest regularity assume a different nature, and produce spores.
These cells are called basidia (meaning small pedestals, V V, Figs.
3 and 4), and the spores, or analogues of ovules or seeds, basidio-
spores, because they are carried on these little pedestals. The
minute threads between the spores and their pedestals are termed
spicules or sterigmata (literally props). Certain other privileged
cells (W W, Fig. 3) are termed cystidia (bladders), and around
these latter organs and their meaning the principal interest of the

12 Reproduction in the Mushroom Tribe.

subject in hand will now centre.

By W. G. Smith.

But let it be borne in mind as a

preliminary fact of the utmost importance that at first the fungus is
composed wholly of simple cells which show no differentiation ;

Fic. 3.—Coprinus radiatus, Fr.
Vertical section and surface of Gill, enlarged 150 diam. V, Basidia with spores;

W, Cystidia.

W.G.S. AD. NAT. SOy

no differentiation in the cells is seen in infancy when the gills are
first formed, but the privileged cells, known as basidia and cystidia,
come only into existence and that simultaneously as the plants
reach maturity. This differentiation I consider to be sexual, the

Reproduction in the Mushroom Tribe. By W. G. Smith. 18

basidia being female, and the cystidia the male organs. When the
contents of the basidia and cystidia are interchanged, the result is a

"W.G.S. AD. NAT. SGa

Fic. 4.—Coprinus radiatus, Fr.
V, Basidia bearing spores; W, Cystidia; X, Y, Spermatozoids.

return to another series of cells, which go to form a new plant. I
am perfectly aware of the opinions which have been expressed by
other botanists (and to which I shall return), but it is not so much

14 Reproduction in the Mushroom Tribe. By W. G. Smith.

my aim to make my observations accord with what others have
said, as to record what I have seen myself, and to give my own in-
terpretation of the phenomena seen, irrespective of what has been
said or done before.

The first sign of differentiation in the simple cells of the gills,
when the basidia and cystidia are about to be produced, is in the
privileged cells becoming glossy, crystalline, and translucent: they
both appear to secrete a material which makes them conspicuously
brilliant. Each basidium then throws out four slender branches,
the tips of which gradually swell and form spores. The cystidia
(W) are more sparingly produced (for their number in this species,
see Fig. 1, H, and Fig. 2, Q), and at first cannot-be distinguished
from the basidia, though they are frequently larger in size; they
are commonly granular within, and are in many species, as in the
one before us, crowned with granules, W (Fig. 4, X), but some-
times they bear four spicules, and this latter condition has led some
botanists to consider the cystidia to be barren basidia, but that they
are really cystidia with spicules is proved by the following fact, which
I believe to be somewhat new. In moisture, as supplied by the
expressed juice of horse-dung (or even distilled water) these spicule-
bearing cystidia germinate at the four points of the spicules, and
produce long threads, which bear at their tips the granules so fre-
quent in typical cystidia (Fig. 4, Y). The cystidia are moreover
furnished with spicules in the subgenus Pluteus. The germinating
cystidia are seen in several places at W, Figs. 3 and 4, and the
granules at X, Y. On the top of Fig. 4 is seen a section of a gill
with all the bodies in position enlarged 550 diameters, whilst on the
lower part of the cut may be seen various germinating cystidia to
the same scale as seen on the surface of a gill. The granules at Y,
which are at first not capable of movement, are really spermatozoids
possessed of a fecundative power, but to see this power brought into
operation considerable care and patience and the higher powers of
the microscope are requisite. In certain other of the Agaricini, the
protoplasmic contents of the cystidia are at times discharged from
one mouth only and that at the apex of the cystidium.

Before quitting Figs. 3 and 4, I may say that when a slice, as
represented in Fig. 3, is placed under a covering glass in a drop of
water, all the cells totally collapse and vanish, so that in three or
four hours not a vestige remains, but the same drop of water which
destroys the old cells instils life into the granules or spermatozoids,
which after the lapse of a couple of hours begin to revolve, and
ultimately swim about with great rapidity. These spermatozoids
attach themselves to the spores, pierce the coat, and discharge their
contents into the substance of the spore. From twenty-four to
forty-eight hours after this the spore discharges a cell which soon
becomes free, and this is the first cell of the pileus of a new plant

Reproduction in the Mushroom Tribe. By W. G. Smith. 15

which rapidly produces others of a like nature (Z, Fig. 3). Now
the same water which had the effect of immediately collapsing and
destroying the old cells, has quite a different effect on the new cells
as discharged from the fecundated spore, for the whole development
of the new plant depends upon the constant presence of moisture,
expressed juice of horse-dung being perhaps best. A spore un-
pierced by the spermatozoids is shown producing a mycelium
peculiar to itself, at A, Fig. 3.

A spore is commonly considered to have some analogy with a
seed, but according to my views its analogy is rather with an unfe-
cundated naked ovule without an embryo, unless the nucleus within
the spore may in some way represent the rudimentary fungus;
when the spores are formed within sacs or asci, the ascus bears
some analogy with the ovary. The cystidium, on the other hand,
represents with its granules the anther and its pollen.

The six spores represented on the top of lig. 5 are magnified
1000 diameters, and each viscid spore, which is furnished with a
nucleus lighter in colour, but with a dark outline, has been pierced
and fertilized by one or more spermatozoids, whilst the unfertilized
spore at A has burst at both ends, and produced a mycelium of its
own. At B may be seen three spermatozoids which have burst
after twelve hours in expressed juice of horse-dung, and which have
also produced branching threads peculiar to themselves, reminding
one of a pollen tube. It is quite possible that these latter threads
may help to produce a new plant if they come in contact with the
spores. The large figure at C is similar in nature to the group at
Z, Fig. 3, and represents three fertilized spores which have burst
and produced the first minute knot or groups of cells of the cap of
a new fungus. These eighteen cells took four days for their pro-
duction, and the crystals belong to the expressed juice of the horse-
dung in which they grew. The spermatozoids as here shown begin
gradually to revolve after being kept in liquid for two hours, and
the movements last for at least four days. At first these bodies are
perfectly spherical, as at D, when they merely oscillate, then they
revolve slowly, and as time goes on, a single turn of a spiral makes
itself visible, and the bodies whirl round with great rapidity. At
intervals the motion entirely ceases, and then, after a short lapse of
time, the gyration is again continued.

Judging from the presence of the eddy round these bodies
whilst whirling (E E, Fig. 5), they are possibly provided with cilia,
but from the extreme minuteness of the bodies themselves I have
not been able to satisfactorily demonstrate their presence. The
whirling of the spermatozoids is sometimes so strong that when
they attach themselves to the spores they twist them round after
the manner of the revolving oosphere in Fucus.

When the cells of the old parent fungus collapse and disappear

VOL. XV. 9

16 Reproduction in the Mushroom Tribe. By W. G. Smith.

in the water, their place isin less than two hours occupied by
innumerable quantities of bacteria, vibriones and monads, which
belong to the infusoria. In these two hours every cell of the pileus

W.C.S. AN, NAT. SC.

Fic. 5.—Coprinus radiatus, Fr.

Spores, Infant plant C, and Infusoria, enlarged 1000 diam. ; Spermatozoids at
bottom further enlarged to 3000 diam.

Reproduction in the Mushroom Tribe. By W.G. Smith, 17

has generally vanished. Where these infusoria come from, or how
they so speedily come into being, is difficult to say. They may
possibly be present in a latent state in the juices of the fungus, but
I have invariably found, when a single specimen of C. radiatus has
been placed on a slide under a covering glass with a drop of water,
and this, again, under a propagating glass, that as the milhons of
fungus cells quickly disappear, so millions of simple infusoria just
as quickly come into being. It seems almost reasonable to believe
that the fungus cells themselves become suddenly transformed, and
reappear as simple infusoria; the change would not be quicker or
more remarkable than the rapid production of the purple-black
spores from the crystalline and colourless basidia.

Be this as it may, I have here engraved the abundant infusoria
to the same scale as the cells. The tailless monads at F have a
rocking Brownian movement, whilst those with tails, G, propel
themselves rapidly about after the manner of minute tadpoles.
These monads are liable (without care) to be mistaken for the
bodies I refer to spermatozoids, from which they are, however, very
different. The bacteria are represented at H H, with their various
movements (indicated by dotted lines), either straight, zigzag, or
rapidly revolving on a central axis; when they so revolve they
cause a miniature vortex amongst the monads and atoms. I have
commonly seen one segment move from side to side, as at J, whilst
the other segment remained quiescent. I have also seen them bud
from the centre, and occasionally they occur with three limbs
instead of two, radiating from the central axis. The vibriones are like
vegetable screws, and are shown at K. ‘The spores and infusoria
neither collapse nor burst in boiling. As for the monads, vibriones,
and bacteria, it can hardly be admitted that they are generated
spontaneously from inorganic materials; my experiments rather
point in the direction that they are only differentiated forms of
already living cells. However this may be, my boiling has not
destroyed either vitality or form, and those interested in the subject
of spontaneous generation may possibly read the result of the
following experiment with interest. A dozen semi-decayed speci-
mens of OC. radiatus, swarming with minute infusoria, were boiled
in a test tube for five minutes and then hermetically sealed at the
highest point of ebullition. At the end of a month tube was
opened and a drop of its liquid contents at once placed under a
cover-glass of the microscope for examination. Spores, cells,
monads, bacteria, and vibriones were all there, but the latter
motionless and apparently dead. In fifteen minutes, however, they
showed signs of life, and began to slightly move about; in thirty
minutes the movements were decided in nearly every specimen seen ;
whilst in sixty minutes the infusoria darted about with almost the
same energy as they did before they were boiled. For a better

c 2

18 Reproduction in the Mushroom Tribe. By W. G. Smith.

appreciation of the exact form and gyrations of the spermatozoids
they are shown again at the bottom of Fig. 5, enlarged 3000
diameters. At first it requires long and patient observation to
make out the form of these bodies satisfactorily, but when the
peculiar shape is once comprehended there is little difficulty in
correctly seeing their characteristic form. The difficulty is some-
thing like that experienced by beginners in separating very small
and close double stars with a telescope; at first and sometimes for
a long period only one star can be seen, till quite suddenly the two
are made out, and they are seen as two ever afterwards.

It is not uncommon to find the spores of other dung-borne fungi
sticking to the specimens of C. radiatus, and it is quite frequent to
find not only the spores but the perfect asci of certain species of
Ascobolus sticking to the under surface, to which position they
have been projected from the plants of Ascobolus growing on the
dung. I have also seen the eggs of various mites, nematoid worms,
&c., carried up amongst the cells, which quite accounts for larve
being found within the substance of apparently sound fungi.

In the works I am acquainted with there is no mention of the
cystidia falling bodily out of the hymenium on to the ground, yet
this is the case in several Agarics 1 have examined, and is so with
CO. radiatus. The spores naturally fall to the earth, and with them
the cystidia, and it is upon the moist earth that fertilization is
generally carried out. All botanists will remember Hoffmann’s
observations, where he has indicated the passage of basidia into
cystidia, and his remarks on the upper surface of the ring which
grows round the middle of the stem in Agaricus muscarius. In this
latter position Hoffmann found a quantity of gelatinous knots, from
which projected one or more oscillating threads, terminated fre-
quently with a little head, which occasionally becomes detached.
My interpretation of these observations is, that Hoffmann lighted
upon the fallen cystidia on the upper surface of the ring, where
they were throwing out threads. Hedwig made somewhat similar
observations on the ring in Agaricus.

From the condition of the infant plant, as figured on the hyme-
nium, Fig. 8, Z, and Fig 5, ©, it is easy to trace the young fungus
through the various stages of its growth, as seen at Fig. 6, where
the figures are all enlarged 500 diameters ; the lower group of cells
shows a plant of seven days’ growth in the expressed juice of
horse-dung. In all these figures it will be seen that crystals and
spores are carried up by the cells, and the lower figure conclusively
shows that the first cells of the new plant are the large ones which
belong to the pileus; indeed the hairs of the pileus as here shown
are amongst the earliest cells produced, these hairs and the threads
of the mycelium (which is always highly granular near the plant)
are almost one and the same in character. In Fig. 6 and

Reproduction in the Mushroom Tribe. By W.G. Smith. 19

Fig. 7 the infant fungus resembles a Puff-ball, to which it indeed
bears a certain natural relationship. The whole plant in infancy

SY cen:

Ss SS

235) uv : eae

————

W.C.S, AD. NAT. SC.
Fic. 6.—Coprinus radiatus, Fr.
Enlarged 500 diam., as grown from the spores, in expressed juice of horse-dung,
under a covering glass of microscope.

is enveloped in a wrapper of cells, the fructification being entirely
concealed within. In the lower figure on Fig. 6 may be seen two
spermatozoids which have burst, and K K K shows the cells of straw.

20 Reproduction in the Mushroom Tribe. By W. G. Smith.

When the fungus has made about the number of cells repre-
sented on the bottom of Fig. 6, the growth cannot be carried any

4

[}
mare.

W.C.S. AD. NAT. SC.

Fic. 7.— Coprinus radiatus, Fr.
Enlarged 200 diam., and natural size at A A A,

further beneath a covering glass. Fig. 7 represents on one side
the elevation, and on the other the section of the very smallest
infant plant it is possible to see with a lens on the dung. The

=

Reproduction in the Mushroom Tribe. By W.G. Smith. 21

fungus represented is magnified 200 diameters, and the original was
about half the size of a pin’s head (see A A A sketch in margin).
The nature of the hairy coating, which forms the veil and the cells
which are to form the future gills, are here clearly seen. This
figure shows the fungus in its Puff-ball condition at the time when
the cells are being actively produced. It contains only a small pro-
portion of the actual cells which go to make up a perfect fungus,
and represents probably a full week’s growth from the spores. How
it is that the cells have an inherent property of building themselves
up into a particular design, no one knows any more than it is known
how the fine spark of life is kept up in these cells from one genera-
tion to another.

The mycelium now grows in a radiate manner from the base of
the young plant, just as a germinating seed throws up a plumule
and throws down a radicle. This mycelium being the produce of
fertilization is now capable, under certain conditions, of producing
new plants on certain spots on the threads. Spores are now un-
necessary, in the same way as fresh seeds are unnecessary where the
creeping root-stock of Couch-grass is present. Or the mycelium
may go to rest in the form of cords or thick threads, when it is
termed Rhizomorpha, or in the form of the knots or bulblets
known as Selerotia. A similar state of things is common in many
perennial. flowering plants, as Convolvulus sepium and Sagittaria
sagittifolia, and they both at first arise from a seed in the same way
as a Mushroom arises from a spore. In Mushroom-spawn the
grower gets a material similar in nature to the root-stock in Couch-
grass.

Fig. 8 and last represents, enlarged 120 diameters, C. radzatus
a few moments before expansion, when nearly all the cells are
present. Most of the cells here shown are, however, only about
one-half the size they reach at maturity, and they are not all and
every one produced till the exact moment of complete expansion, as
I have ascertained by counting the cells of many specimens. This
is not to be wondered at, for if the 22,500,000 cells which go to
make up one of these minute plants require fourteen days for their
production, it follows as a necessity that the cells go on multiplying
all the fortnight, night and day, at the rate of 1114 to the minute.
It takes about five hours for the spores to be gradually produced all
over the hymenium—say from 5 to 10 o’clock in the morning, and
as there are upwards of 3,000,000 spores to each plant, they as a
consequence gradually appear upon the basidia or spore-bearing
spicules at the rate of 100,000 every minute.

No sooner has the plant arrived at perfection than that very
moment it begins to perish. I have demonstrated that the cells of
the pileus and the hairs which form the veil are the first to appear,
and so they are the first to disappear. The fine matted hairs

22 Reproduction in the Mushroom Tribe. By W. G. Smith.

which form the veil in Fig. 8, B BB, are ali torn assunder during
the few moments consumed in the expansion of the cap, and at the

ys

oe

cee ee eet eee
~~

eee

—*

— one

o\\
(\ Us:e@ens
NSS Neae==

ul
—_—S—SSSSSS=—=— SS
== BSS

===

GS AU.NAT. SC,
Fic. 8.—Coprinus radiatus, Fr.
Enlarged 120 diam.

moment of maturity the hairs vanish and the pileus is naked, which
nakedness is the first sign of its decay. When the fragile little

Reproduction in the Mushroom Tribe. By W. G. Sith. 23

fungus has at length produced its fruit, and is prostrate and dying
upon the matrix from which it sprang, then, as can be seen with
patience under the microscope, the cystidia produce spermatozoids
which are at first passive and then active; these pierce the spores
and cause the discharge of the first living cell of the pileus of a
new plant. It will be seen from these observations that C. radiatus,
though one of the most minute and fugitive of all the Mushroom
tribe, is yet as completely perfect in all its parts as any of the
larger and higher species of Agaricus. It must not be supposed
that these observations can be followed without close attention and
the utmost patience. All the 3,000,000 spores of the fungus do
not grow and make new plants, or the world would soon be covered
with C. radiatus. For every spore that is fertilized and grows,
there are millions which necessarily perish.

On a dungheap which will produce C radzatus, other species,
as C. nycthemerus, &c., are sure to appear; and not only do allied
Species come up in company with C. radiatus, but every inter-
mediate form between one and the other may be gathered any
morning. These latter plants belong to no species described as
such, but are natural hybrids, doubtlessly produced by the sperma-
tozoids of one plant piercing the spores of another. Amongst the
larger species of Agaricus similar forms are quite common, and
they prove sore puzzles for those men who only want names for
the fungi they find. I am convinced that at least three-fourths of
the described species of thé higher fungi have no claim to rank as
true species, and that plants like Agaricus procerus, A, rachodes,
A. excoriatus, A. gracilentus, with others, are mere forms of one
and the same plant, and every intermediate form may be met
with.

Van Tieghem has recently been working on this species, and he
has arrived at the conclusion that the fungus produces spores of
different sexes. But to me it is quite unreasonable to imagine
seeds or spores to be of different sexes. Known facts point quite
in the opposite direction; and if sex is once allowed in seeds and
spores, then we must be prepared to allow sex in pollen and sperma-
tozoids. A spore or ovule must be considered female, whilst unfe-
cundated or still in the ovary, but when once fertilized it combines
both sexes and cannot be other than hermaphrodite. A secondary
colour, as orange (which combines the red and yellow primaries),
can never be red or yellow. In dicecious plants the seeds are
capable of producing either sex, and are not themselves male or
female ; and even the great fleshy root-stock of Bryonia dioica will
be male in one place, and if removed to a different position be
female. The Rev. M. J. Berkeley, writing of Coprinus,* says :
‘Late examinations of the spores of some Coprinus under germi-

* ‘Gardeners’ Chronicle,’ April 17, 1875, p. 503.

24 Reproduction in the Mushroom Tribe. By W. G. Smith.

nation seem to show that impregnation takes place at a very early
eriod.”’

! Now my observations show that this impregnation often actually
takes place on the hymenium itself, the product being a single cell,
which in the species now described rapidly develops into a new
individual. The spore and spermatozoid may be considered as
somewhat analogous with an oyule and a pollen grain, or with what
is seen in Chara; or like the escaped oosphere and spermatozoids
in Fucus amongst the Alge.

I cannot attach much importance to Cirsted’s teresting paper
on the fructification of the Agaricini. His notes are on Agaricus
variabilis, a plant he gathered from a Mushroom bed. Now, as
far as my experience goes, A. variabilis is peculiar to dead stems,
sticks, and leaves, and does not grow upon dung. Moreover,
(Ersted experimented upon threads of mycelium taken from dung,
and presumed only to belong to this Agaricus; but this mycelium
was quite as likely, in my opinion, to have belonged to fifty other
things. De Bary, speaking of Cirsted’s observations, says: “ It is
impossible not to perceive the similitude between the phenomena
seen by M. Cirsted and those I have described in Peziza con-
fluens.” Tt is quite doubtful whether or not Girsted had got the
mycelium of some dung-borne Peziza for his experiments, as
P. vesiculosa, which is always present on dungheaps.

In the observation of natural phenomena it is never well to
follow, without thought and original observation, in the footsteps
of others. In the case of Peronospora infestans, because De Bary
said the resting spores were not likely to be found in the Potato
plant, it was almost universally accepted as a fact that they never
could be there found. Because conidia had not been described, it
was commonly believed that no conidia existed. The mycelium of
Peronospora has till lately been described as always destitute of
suckers, but in some of the Chiswick plants the suckers were abun-
dant. The same fungus is commonly described as haying its threads
without articulations or septa, but it is equally common to see the
fungus and the figures of it too with septa in profusion.

Many botanists, as Corda, Bulliard, Klotzsch, and others, have
considered the cystidium in Agaricus to correspond in some way
with an antheridium; but as these views have not at present been
favoured by Tulasne and De Bary, many botanists seem disposed to
agree with De Bary in regarding the cystids as mere “ pilose pro-
ductions of a particular order,’ which is very indefinite, and the
granules as mere conidia (Tulasne). Klotzsch and others have con-
sidered it possible that the spores are fecundated by a lubricating
fluid given out by the cystidia. ‘This fluid is evidently the same
with the threads observed by me, and which at length gives birth
to spermatozoids. I consider it quite possible that the mere contact

Reproduction in the Mushroom Tribe. By W.G. Smith. 25

of the threads (or fiuid) from the cystidia with the threads from the
unpierced spores may be sufficient for the production of a new
plant. But De Bary, in criticising Klotzsch, says an opinion of
this nature is entirely gratuitous, and the contact and its result, if
real, would represent nutrition rather than fecundation, and, as far
as he knows, there exists, he says, no other observation on any
female organ susceptible of fecundation by the cystidia. I cannot
fall in with De Bary’s views at all, especially after the analogy
found in Fucus and in the confervoid pollen (which has no outer
coat), and which exhibits rotation in the flowering plants found
under Zostera, Phucagrostes, &c., and which are fecundated when
in a state of immersion in water.

As regards the spores of woody species of fungi, they are pro-
bably fertilized on the parent plant, and are blown away by the
wind in a condition suitable to at once form the first cells of a new
plant on any proper habitat. If Agarics were perennial and per-
sistent, instead of being annual and fugitive, we might expect to see
a new hymenium produced each year upon the lower surface of the
old one, and this state of things really does exist in many species
belonging to the perennial and persistent woody fungi of trees,
where a new stratum of tubes is every year produced underneath
the old one, so that the age of the fungus in years may be correctly
ascertained by merely counting the strata. As to the mycelium
itself, and the possibility of its producing sexual organs in Agaricus,
I have had the subject before me for many years, and have seen
many germinating spores, but no trace of any sexual organ other
than the spermatozoids as produced from the cystidia themselves,
or from the protoplasmic filaments which they throw out. I am
therefore disposed to believe that the absence of sexual organs
on the mycelium is owing to the threads being the produce of
fertilization.

As for the expressed juice of horse-dung, it abounds with nema-
toid worms, spores and infusoria of many kinds—no drop can be
examined from a dungheap after a shower of rain without seeing
large quantities of these organisms. Therefore, any uncertain
thread taken for examination from dung is sure to lead to error.
All my experiments were carried out in duplicate, one with ex-
pressed juice, and the other with distilled water, with very little
difference in result, as the new plant seemed to live principally on
the remains of the old parent.

As a proof of how much there is still to be learnt respecting
the life history of Agarics, I may say that in Sach’s recently pub-
lished ‘ Text Book of Botany,’ one of the very best and most
complete books of its class ever published, there is no mention
whatever made of cystidia in the description of Agaricus, and in La
Maout and Decaisne’s ‘ Descriptive and Analytical Botany,’ under

26 Avoiding the Use of the

fungi, it is stated that the male organs never produce anthero-
zoids, and that the cystidia are always deprived of sterigmata or
spicules.

To repeat and follow out these observations it is necessary to
take the specimens for examination exactly at the proper period of _
growth, and to exercise the greatest care in securing a uniform
moisture between the glasses. The life of the fungus is so short,
and all the characters are so evanescent, that the points to be
observed may be present one moment and all gone the next.

All the drawings have been made with a camera-lucida, and
from different specimens, so where the dimensions of the parts
slightly disagree, it is only such a disagreement (within defined
limits) as is commonly found in Nature.—Gardeners’ Chronicle,
October 16 and 23.

III. —Avoiding the Use of the Heliostat in Micro-photography.

By G. M. Girxs, M.M.MS.
Puate CXXVII.

Some time ago I commenced to make some experiments in micro-
photography. I did not wish to set aside a room to act as a camera,
as in the method of Colonel Woodward, and did not like the form
of instrument mentioned in the catalogues of the instrument makers,
as in the first place it is very top-heavy, and in the second the
disk produced, I found on inquiry, was no larger than a “ five-franc
piece.” Above all things I wished to avoid the necessity of using
a heliostat. ‘

I was therefore constrained to contrive an apparatus to meet
these requirements, which I have no doubt are those of a great
many histologists. The image produced by an ordinary condenser
of short focus is so small, that unless a heliostat be used, it is almost
impossible to replace the focussing screen by the sensitized plate
before, on account of the rotation of the earth, the image has passed
across the field of the instrument and disappeared. Now the obvious

EXPLANATION OF PLATE CXXVII.

Fias. 1 and 2, a.—Stand of camera.
Pe » 6—Mirror.
» ¢—Long-focussed condenser.
33 », @—Microscope and its slider.
5 3, @-—Grooved wheel at back.
5 » j.—Strings of horizontal movement.
FA » g-—Strings of vertical movement.
Fic. 3.—Section mode of connection of microscope with camera,
», 4.—Sectional view of “tramway.”

“em 0% SMM sm Ie ac Ly Ol de 309.0 AO AO TIA]

SO EY srs ssn

[fs

MAXX) Td ‘OL.Q] | usp peuanopeotdoosozorpy Apu; uo eg |

Heliostat in Micro-photography. By G. M. Giles. 27

remedy for this appeared to me to enlarge the disk of light that is
thrown on the object. By putting the condenser out of focus one
obtains a larger disk, but this at the expense of a great loss of light,
besides which circles of varied colours are thus produced of equal
variety of actinic power.

In order therefore to produce a sufliciently. large image, I de-
termined to make use of a telescopic objective as condenser, instead
of the usual short-focussed lenses that are used for this purpose.

The glass ultimately employed was an achromatic, photographic,
single combination of 33 inches diameter, and about 10 inches focal
length.

The employment of this condenser necessitated other changes
which have resulted in the form of apparatus I am about to
describe.

It consists of a strong base board of wood about 5 feet long by
1 foot broad. Erected along one-half of this is a sort of stage, of
sufficient height to raise the centre of the camera to a level with
the tube of the microscope when in a horizontal position.

The camera, which should be of the“ bellows” kind, capable of
being drawn out to about 2 feet, and of such a size as to take
plates of 6 inches square, is secured to this by means of binding
screws. At the opposite extremity of the instrument is the mirror ;
this is about 4} mches square, and is mounted, like an ordinary
swing-glass, on a circular base-piece about 10 inches in diameter.
This circular stand of the mirror is capable of being rotated round
a pivot fixed in the base-board, and has its edge grooved. The
part of the pivot that projects above the level of the stand, supports
a couple of pulley sheaves.

On account of the length of the instrument, it is necessary
that the mirror should be capable of being moved by strings from
behind. These are arranged as follows. One endless band passes
round the groove in the stand of the mirror, and through sheaves
let into the back part of the stand for the camera. A second cord
by which the mirror is moved on its horizontal axis is arranged
thus. One end is fastened to the upper border of the mirror ; it is
next passed through one of the sheaves on the pivot; and is then
carried back between the legs of the microscope to a grooved wheel
about 2 inches in diameter, provided with a handle, fixed at the
back of the instrument; a turn is made round this, and the cord
brought back through the remaining sheave on the pivot to be
fastened to the lower border of the mirror.

Between the mirror and the stand for the camera is a sort of
tramway, the entire breadth of which should not be more than
8 inches. Sliding easily in this is the stand of the long-focussed
condenser. This consists of two vertical wooden supports, across
the top of which is a transverse piece with an opening into which

28 Avoiding the Use of the

fits the condenser, the centre of which is elevated to such a height
as to be opposite the tube of the microscope. Behind this lens the
alum cell fits into a slit made to receive it in the upright pieces.
Behind the condenser is a firmly sliding piece of wood, in which
holes are cut to receive tightly the feet of the microscope.

The camera is.connected with the microscope as follows. To
the front of the camera is fixed a wide metal tube, which is con-
nected to a somewhat smaller one by a joint of cloth.

This smaller tube ends in one which loosely fits the tube of the
microscope, and which is lined with thick wash-leather in order to
exclude all light.

Supposing then that one wishes to photograph any part of an
object. The slide is fixed in position by means of the springs
usually attached to the stage of the microscope, and its draw-tube
pulled out. It is then inclined to a horizontal position, the mirror
turned aside, and its feet fixed in the holes cut for their reception in
the sliding piece which is then pushed back, so that the tube slips into
the collar of the camera. The draw-tube is then replaced from the
inside of the camera, the flange, with which it is generally provided,
thus effectually shutting out any light that might otherwise enter.
The alum cell which should contain a thickness of about half an
inch should next be placed in the slit and filled with a concentrated
solution of alum. ‘The apparatus should then be placed across a
table in front of an open window, out of which the mirror should
be made to project so as to be out of shadows cast by the eaves, the
base-board being so placed that the reflexion may take place at as
acute an angle as possible. The window-blind should then be let
down so that it hangs just above the condenser and turned as
dark as possible, by which means the nuisance of a focussing cloth
is avoided. Then seating oneself so as to be able to watch the
focussing screen, the light is thrown on to the object, and the con-
denser focussed so as to throw a distinct image of the sun on the
slide. After which the light is cut off by turning round the wheel
of diaphragms preparatory to inserting the sensitized plate.

Here I would remark that it is a good plan to close all the holes
in the diaphragm with pieces of nonactinic paper with the excep-
tion of one of moderate size, and to loosen the screw on which it
pivots in order that it may turn as easily as possible.

Then having replaced the focussing screen by the dark slide
and raised the shutter, the exposure is made by turning round the
diaphragm wheel so that the opening in it may pass swiftly across
the aperture in the stage; the shutter is then closed and the plate
taken to the operating room for development.

Ground glass is rather too coarse a material for the focussing
screen in micro-photography ; for this purpose a piece of patent plate
over which has been poured a film of mucilage of starch, or some

Heliostat in Micro-photography. By G. M. Giles. 29

matt varnish, is better. The instrument may be used either in its
simple or its compound form; in other words, with or without the
eye-piece.

When the eye-piece is not used, the camera must be drawn out
to a great length to obtain sufficient amplification, whereas at 10
inches distance from the eye-piece one gets the full nominal power
of the instrument.

On the whole, I prefer to use the eye-piece, though seldom at
the full 10 inches.

Almost any good objective will give good results, but micro-
photography is a very trying test to a glass.

A very essential quality is flatness of field ; should this be want-
ing, its absence will be painfully conspicuous in every impression
taken. When the sun shines clearly, the most preferable process is
the ordinary wet collodion, on account of its handiness and easiness ;
but wet plates will not bear being kept for more than five or ten
minutes before exposure, so that they are very inconvenient to use
in cloudy weather when the sun shines out only occasionally be-
tween the clouds. On such occasions it is better to use dry plates,
in the form of the gelatine-bromide process. They have the ad-
vantage too, that one may develop them at one’s leisure, but require
care In exposure, as they are more sensitive than ordinary collodion.
The gelatine process which I use is that patented by Mr. Kennett,
of Maddox Street.

By means of this process good micro-photographs may be ob-
tained by the light of a paraffin lamp. When photographing at
night by paraffin light or by the magnesium lamp, it is not neces-
sary to use the long-focussed condenser; the source of light being
stationary, it is more advantageous to use an ordinary achromatic
condenser, the mirror of the microscope being made use of as the
reflector. The exposure with paraffin light is necessarily long—
two minutes with low, and as much as fifteen with high powers.
Representations of microscopic objects obtained by photography have
this advantage over drawings, that it cannot be said that they show
merely what the observer thinks he sees. Whatever is shown must
be there, but on the other hand one plane of focus only can be
represented, so that the sharp outlines of drawings must not be
expected, especially in the case of the rounded bodies of which the
majority of tissues are composed.—Read before the Medical Micro-
scopical Socrety, November 19, 1875.

( 380 )

1V.—Improved Method of Applying the Micro-spectroseopie Test
for Blood-Stains. By Jos. G. Ricnarpson, M.D., Attending
Physician to the Presbyterian Hospital; Microscopist to the
Pennsylvania Hospital.

Tux value to medical jurisprudence of spectrum analysis as employed
for the detection of dried blood is so fully established by the re-
searches of H. G. Sorby, Dr. W. B. Herepath, Professor A. 8. Taylor,
W. Preyer, and others, that it seems unnecessary for me to do more
than state that the demonstration of the two dark bands in the
green caused by scarlet cruorine (hemoglobm), such as that con-
tained in a recent blood-stain, enables experts to discriminate
positively blood from other red colouring matters soluble in water,
whether mineral, vegetable, or animal, except an extract of the red
feathers from the Turacus adbocristatus, a bird found in the East
Indies, and quite unknown on our continent of America.

Valuable as this test is thus seen to be, there are, unfortunately,
several circumstances which limit its general application, as, for
example, the changes in the constitution of hemoglobin which
occur from prolonged and frequently from comparatively brief
exposure to the air, the modification of the absorption bands caused
by the presence of other substances, and last, but not least in many
instances, the difficulty of procuring sufficient material for experi-
ment. The insuperable nature of this latter obstacle will be at
once appreciated when I mention that whilst the smallest amount
which Sorby, Herepath, and Taylor furnish directions for testing is
a spot “one-tenth of an inch in diameter, or a quantity of the red
colouring matter amounting to no more than one thousandth part of
a grain, the important stain upon an axe-handle supposed to have
been used in a murder I am now investigating probably weighed
less than one three-thousandth of a grain when entire and uninjured.

The exigencies of this case have led me to seek out some other
method than that of Mr. Sorby, who recommends that a solution of
the suspected colouring matter should be made in a few drops of
water contained in a cell composed of a piece of barometer-tube
half an inch long and one-seventh of an inch in diameter. After
numerous experiments, I contrived the following plan, which, on
trial, proved satisfactory beyond my most sanguine expectations,
enabling me to reveal the presence of blood in a quantity of matter
only one one-hundredth the amount directed by Mr. Sorby.

Procure a glass slide, with a circular excavation in the middle,
called by dealers a ‘“ concave centre,” and moisten it around the edges
of the cavity with a small drop of diluted glycerine. Thoroughly
clean a thin glass cover about one-eighth of an inch larger than
the excavation, lay it on white paper, and upon it place the tiniest
visible fragment of a freshly-dried blood-clot (this fragment will

Micro-spectroscopic Test for Blood-Stains. By Dr. Richardson. 21

weigh from one twenty-five-thousandth to one fifty-thousandth of a
grain). Then with a cataract-needle deposit on the centre of the
cover, near your blood-spot, a drop of glycerine about the size of this
period (.), and with a dry needle gently push the blood to the
brink of your microscopic pond, so that it may be just moistened
by the fluid. Finally, mvert your slide upon the thin glass cover
in such a manner that the glycerined edges of the cavity in the
former may adhere to the margins of the latter, and, turning the
slide face upwards, transfer it to the stage of the microscope.

By this method, it is obvious, we obtain an extremely minute
quantity of strong solution of hemoglobin, whose point of greatest
density (generally in the centre of the clot) is readily found under
a 4-inch objective, and tested by the adjustment of the spectroscopic
eye-piece. After a little practice it will be found quite possible
to modify the bands by the addition of sulphuret of sodium solution,
as advised by Preyer.

In order to compare the delicacy of my plan with that of
Mr. Sorby, a spot of blood one-tenth of an inch square may be
made on a piece of white muslin, the threads of which average one
hundred to the inch. When the stain is dry, ravel out one of the
coloured threads and cut off and test a fragment as long as the
diameter of the filament, which will of course be a particle of stained
fabric measuring one one-hundredth of the minimum-sized piece
directed by Mr. Sorby. When the drop of blood is old, a larger
amount of material becomes requisite, and you may be obliged to
moisten it with aqua ammoniz, or with solution of tartrate of
ammonium and protosulphate of iron; but in the criminal case
referred to, five months after the murder, I am able from a scrap of
stained muslin one-fiftieth of an inch square to obtain well-marked
absorption bands, easily discriminated from those produced by a
solution of alkanet-root with alum and those caused by infusion of
cochineal with the same salt.

In cases of this kind, where the greatest possible economy or
even parsimony of material is needful, I would advise the following
mode of procedure for proving and corroborating your proof of the
existence of blood, so that its presence in a stain may be affirmed
with absoluie certainty.

From a suspected blood-spot upon metal, wood, leather, paper,
muslin, or cloth, scrape with a fine sharp knife two or three or
more minute particles of the reddish substance, causing them to
fall near the middle of a large thin glass cover. Apply in close
proximity to them a very small drop of three-fourths per cent. salt
solution,* bring the particles of supposed blood-clot to its edge, and
proceed as I have already directed.

* See my paper “On the Value of High Powers in the Diagnosis of Blood-
Stains,” ‘American Journal of the Medical Sciences,’ July, 1874, p. 109.

VOL. XV. D

32 Micro spectroscopic Test for Blood-Stains. By Dr. Richardson.

After thus examining the spectrum of the substance, you may
generally, by rotating the stage, cause the coloured fluid to partly
drain away from the solid portion, wherein, under favourable
circumstances, should the specimen be blood, the granular white
blood-globules become plainly visible, as do also cell-walls of the red
disks. Among the latter, if your mental and physical vision is keen
enough, you can by the aid of a =';th immersion lens and an eye-
piece micrometer measure a series of corpuscles accurately enough
to discriminate human blood from that of an ox, pig, horse, or sheep.

Lastly, to make assurance triply sure, lift up the thin glass
cover, wipe off the tiny drop of blood solution and clot you have
been examining on the folded edge of a thin piece of moistened
blotting-paper, let fall upon it a little fresh tincture of guaiacum,
and then a drop of ozonized ether, which will at once strike the
deep blue colour of the guaiacum test for blood.

In this way I have actually obtained these three kinds of
evidence, to wit, that of spectrum analysis, that of the microscope,
and that of chemical reaction, from one single particle of blood,
which, judged by a definite standard,* certainly weighed less than
one fifteen-thousandth, and probably less than one twenty-five-
thousandth, of a grain.

Although Mr. Sorby claims to be able to demonstrate the
absorption bands from a single red blood-corpuscle, yet, as his
instructions for detecting blood-stains, quoted above from the
‘Quarterly Journal of Science, vol. ii. p. 198, are reiterated in his
paper in the ‘Monthly Microscopical Journal’ of July 1871, p. 9,
and seem to be those solely relied upon by Dr. Herepath, in the
‘Chemical News,’ 1868, vol. i. p. 124, by Prof. L. S. Beale, in his
‘How to Work with the Microscope,’ London, 1868, p. 222, by
Dr. W. B. Carpenter, in ‘The Microscope and its Revelations,
5th ed., London, 1875, p. 121, and by Prof. A. S. Taylor, in Guy’s
Hospital Reports, 1809, p. 274, and in his ‘ Principles and Practice
of Medical Jurisprudence,’ 1873, vol. i. p. 542, and since W. Preyer t
advises no more delicate mode than making and examining a
solution in a watch-glass, I feel justified in offering my method to
microscopists and medical jurists, as an improvement in the ordinary
and facile application of spectrum analysis to blood-stains, by which
this important test is rendered at least one hundred times as delicate
as it has hitherto been when employed according to the directions
of the highest British or Continental authorities, thus enabling us
to detect a recent blood-spot on white muslin covering one ten-
thousandth of a square inch and forming a speck scarcely visible to
the unassisted eye.—Read before the Biological and Microscopical
Section of the Academy of Natural Sciences, Philadelphia, U.S.A.

* See ‘Handbook of Medical Microscopy,’ Phila., 1871, p. 283.
t ‘Die Blutkrystalle,’ Jena, 1871, s. 114.

PROGRESS OF MICROSCOPICAL SCIENCE.

The Spermatozoa of Petromyzon.—Mr.George Gulliver, F.R.S., says :*
“Tn my paper ‘ On certain Points in the Anatomy and Economy of the
Lampreys, published in 1870,f there is an engraving of the sperma-
tozoa of Petromyzon planert. But I know not that those of P. marinus
have ever been described or depicted ; and they differ curiously in the
two species. The spermatozoa of P. marinus, notwithstanding the
great size of the species, are much the smallest, and have a distinct
and rounded head. Their mean length is about ;,),5 inch, and their
thickness z3}55- ‘They were obtained from a fish thirty-two inches
in length and three pounds in weight, taken on May 12, 1874, in the
river Stour, near Sturry Mill, about two miles below Canterbury.
The milt, which distended the whole abdomen from the pericardium
tc the anus, was a soft pulpy mass chiefly composed of a creamy
semen, and so rich in and crowded with spermatozoa of such minute-
ness that they were with difficulty distinguishable; and it was not
before the semen had been much diluted and placed under Powell and
Lealand’s ;1,th objective that a good view of them was obtained. Under
a lower power, especially in the pure semen, nothing more than con-
geries of indistinct rounded points appeared, like those which I have
described in the ‘ Proceedings’ of this Society t as the ‘ molecules of
the semen. In short, unless great care be taken, the spermatozoa in
the ripe testis are so very faint, minute, and abundant, that they are
‘likely to escape detection. But the spermatozoa of the little Petro-
“‘myzon planeri are much larger and more easily seen. They are club-
shaped, without a distinct head, and have an average length of 355
inch, and a thickness of 353,55. They were obtained in April from
a fish six inches in length and two drachms in weight. Further
details concerning the generative organs of both sexes are given in
the paper first quoted in the present communication.”

The Leaf Glands of Saxifraga tridactylites—An addition to our list
of carnivorous plants is suggested by Mr. J.C. Druce in a letter to the
‘Pharmaceutical Journal,’ in a little early spring flower found chiefly
on the tops of walls, Saxifraga tridactylites, a plant not very distantly
allied to the Droseras. Mr. Druce states that when examined under
the microscope the leaves are seen to be covered with glands of a
similar character which exude a viscid secretion, in which he found
a midge was entrapped and held fast when placed on the leaf. On
examining a number of leaves, he found in all of them the débris of
insects which had apparently perished in this manner.

Presence of Micrococcus and Bacteria in the Walls of Hospital
Wards.—The analyses of the air, and other experiments made by
Pasteur, for the purpose of investigating the doctrine of spontaneous
generation, have demonstrated that the germs of inferior organisms
—micrococci, bacteriw, &c.—are everywhere present in the air. In

* ‘Proceedings of the Zoological Society.’ + Ibid., 1870, p. 844.
t Ibid, 1842; p.99.
p 2

34 PROGRESS OF MICROSCOPICAL SCIENCE.

a hospital the air contains a greater number of these elements,
and in addition certain special bodies, such as pus-globules, spores
of epiphytic parasites, which emanate from diseased organisms, and,
owing to their volatility after desiccation, are susceptible of hovering
in the atmosphere. In 1865, M. Broca discovered pus-globules in
the liquid expressed from the sponge with which the walls of
one of the wards of the St. Antonio Hospital had been washed. In
1860, M. Chalvet was inclined to attribute the blue coloration which
is often observed in the vicinity of wounds to the presence of micro-
scopic alge of the species Palmella. In 1861, Dr. Hiselt, of Prague,
placed an instrument, analogous to the aéroscope of Pouchet, between
two beds, in a ward occupied by thirty-three children with purulent
ophthalmia; the apparatus consisted of a glass plate coated with
glycerine, and pus-globules were distinctly seen. To the above and
analogous facts, which are recorded in the dissertation of Dr. Deville
(Strasbourg, 1860), are to be added the recent experiments of
Dr. Nepven, of Paris: One square metre of wall in the surgical ward
of La Pitié having been washed after neglect for two years, the liquid
expressed from the sponge (about thirty grammes) was examined
immediately afterward. It was black, and showed micrococcus in
large amount, several bacteria, epithelial cells in small number,
several pus-globules, several red globules, and, lastly, irregular,
blackish masses and ovoid bodies of unknown nature. The experi-
ment was conducted with all possible precautions.

Bacteria found in the Perspiration of Man.—Dr. Eberth, of
Ziirich,* has, says the ‘ Medical Record,’ found, by aid of the micro-
scope, in the sweat from the face, some corpuscles which he con-
sidered as bacteria. 'This view became confirmed when he examined
the axilla, breast, and inner side of the thigh of several persons in a
state of perspiration. The sweat of these parts contained nearly
always enormous numbers of bacteria. In most cases they originated
from minute bodies found upon the hairs in the mentioned regions,
forming little nodules on them, and giving them a greyish or a brick
colour. They were recognized by the author as accumulations of
micrococci. They may rapidly increase in number, are smaller than
the diphtherial micrococci, and are nearly indifferent to reagents
(concentrated acids, alkalies, alcohol, ether, chloroform). Iodine
colours them yellow. The vegetation of bacteria on the hairs may
be observed in cases where they are changed already, beginning in
places which have clefts between their cells. The vegetation occupies
large spaces, especially in the direction of the longest diameter of the
hair. Dr. Eberth observed a mycelium and micrococci, and thinks
that the latter are the fruits of the former. Other investigators
observed coloured sweat, red and blue, which contained micrococci.
It was difficult to decide in these cases if the colouring matter
was adherent to the micrococci, or if it was a product of the vegetation.

The Migrations of the White Corpuscles.—The ‘ Medical Record’
says that Dr. Jul. Arnold, of Heidelberg + has examined the con-

* Virchow’s ‘ Archiv,’ vol. lxii. + Ibid.

PROGRESS OF MICROSCOPICAL SCIENCE. BO .

ditions under which red blood-corpuscles emigrate, and the question
arose whether the white blood-corpuscles leave the walls of the
vessels in the same manner, or whether they penetrate the epithelial
plates themselves. To decide this question, he examined the
mesentery, the tongue and the bladder of the rana temporaria and
the rana esculenta, and found that generally the white corpuscles
leave the vessels by means of stigmata. The irritation of the organs
was caused in different ways. ‘Thus, the mesentery was exposed for
a few hours to the atmosphere, while the tongue was injured and
the bladder was injected by a weak solution of nitrate of silver.
Infusions of cinnabar into the blood were also made with the view
to colour the white blood-corpuscles. Twenty-four hours after the
operation the animals were bled to death, and then the circulatory
system was injected from the aortic bulb by a solution of nitrate of
silver from 5,55 tO z55- The examination of the preparation took
place immediately in a three-fourths per cent. solution of chloride
of soda, or after colouring with carmine in glycerine. The white
corpuscles could be observed in numerous phases of emigration,
The transmigration always took place at certain points (stigmata).
Had the process of emigration been stopped in time, the emigrated
blood-corpuscles were to be seen in the sheath of vessels, or at a
short distance from this. The form of the white corpuscles is
elongated in the state of escape. Many of them have prolonga-
tions, fixed in the stigmata. Sometimes numbers of white corpuscles
accumulate on the outer wall of the vessels, so that the lining
epithelial membrane appears to be separated from the sheath of the
vessel. The author never observed that the plates themselves were
penetrated by the white corpuscles. As a result of the disturbance in
circulation, combined with the emigration of white blood-corpuscles,
it was found that the borders of the cells forming the vessels are not
so distinct as in a normal state. Between them are a greater number
of dark spots (stigmata) than in a normal state, generally not so large
that red blood-corpuscles could pass them. Dr. Arnold observed
that granules of cinnabar, as well as colloid substances, may leave the
vessels through the stigmata. The cause of the easier penetrability
of the vessels may be found in an alteration of the condition of the
cement connecting their cells. A great number of the emigrated
white corpuscles are carried off by the lymph-vessels. The author
thinks that with the disturbance in circulation during emigration
there are connected currents directed towards the walls of the vessels,
and that they are of different strength.

The supposed Renal Organ in Crustacea.—Mr. A. 8. Packard, jun.,
in a recent paper says, that in dissecting the king crab one’s atten-
tion is directed to a large and apparently important gland, conspicuous
from its bright red colour contrasting with the dark masses of the liver
and the yellowish ovary or greenish testes, and presenting the same
appearance in either sex. “The glands are bilaterally symmetrical,
one situated on each side of the stomach and beginning of the intes-
tine, and each entirely separate from its fellow. One of these glands
consists of a stolon-like mass, running along close to the great col-

os

6 PROGRESS OF MICROSCOPICAL SCIENCE.

lective vein, and attached to it by irregular bands of connective tissue,
which also holds the gland in place. From this horizontal mass, four
vertical branches arise, and lie between and next to the partitions at
the base of the legs, dividing the sides of the body into compartments.
The posterior of these four vertical lobes accompanies the middle
hepatic vein from its origin from the great collective vein, and is sent
off opposite the insertion of the fifth pair of feet. Half-way between
the origin of the vein and the articulation of the foot to the body, it
turns at a right angle, the ends of the two other lobes passing a
little beyond it, and ends in a blind sac, less vertical than the others,
slightly ascending at the end, which lies just above the insertion of the
second pair of feet. The two middle lobes are directed to the col-
lective vein. Each lobe is flattened out somewhat and lies close to
the posterior wall of the compartment in which it is situated, as if
wedged in between the wall, and the muscles between it and the

anterior portion of the compartment. Each lobe also accompanies —

the bases of the first four tegumentary nerves. I could not by in-
jection of the gland, make out any general opening* into the cavity of
the body or any connection with the hepatic or great collective vein ;
any attempts to inject the gland from the veins failing. The four
lobes certainly end in blind sacs. The lobes are irregular in form,
appearing as if twisted and knotted, and with sheets and bands of con-
nective tissue forming the sheaths of the muscles among which the
gland les. Each lobe, when cut across, is oval, with a yellowish
interior and a small central cavity, forming, evidently, an excretory
duct. The gland externally is of a bright brick red. The glandular
mass 1s quite dense, though yielding. It is singular that this con-
spicuous gland, though it must have engaged their attention, has not
been noticed by Van der Hoeven, Owen, or A. Milne-Edwards in their
accounts of dissections of this animal. When examined under a
Hartnack’s No. 9 immersion lens and Zentmayer’s B eye-piece, the
reddish external cortical portion consists of closely aggregated irre-
gularly rounded nucleated cells of quite unequal size, and scattered
about in the interstices between the cells are dark reddish masses
which give colour to the gland. They are very irregular in size and
form, and twenty hours after a portion of the parenchyma was sub-
mitted to microscopic examination vibrated to and fro. Iam reminded
in the vibrating movements of these bodies, of Siebold’s} description of
similar bodies in the renal organs of the Lamellibranchs, i.e. the gland
of Bojanus. He says in a footnote, p. 214,} ‘If the walls of these
organs are prepared in any way for microscopic examination, a part
of their parenchyma separates into a vesiculo-granular mass, the
particles of which have a very lively dancing motion. The motions
are due to portions of ciliated epithelium adhering to the cells and
granules.’ ”

“Jn other portions of the outer reddish part of the gland, where

* Leydig (‘ Naturgeschichte der Daphniden’) states that several anatomists,
after laborious attempts, have failed to find the opening to the green gland in
any crustacean.

+ ‘Anatomy of the Invertebrates,’ { Buruett’s Translation,

a

(se)

NOTES AND MEMORANDA.

the pigment (?) masses are wanting, the mass is made up of fine
granular cells, not nucleated. Other cells have a large nucleus filled
with granules and containing nucleoli.”

ke. “In the yellowish, or, as we may for convenience call it, the me-
dullary portion, are scattered about very sparingly what are probably
the round secreting cells. The nucleus is very large and amber
coloured, with a clear nucleolus; others have no nucleolus, and the
small ones are colourless.”

“T am at a loss to think what this gland with its active secreting
cells, filled with a yellowish fluid, can be, unless it is renal in its
nature. This view is borne out by the fact of its relation with the
hepatic and great collective vein. If future examination shows some
outlet into the venous circulation, then its renal nature would seem
most probable. No other organ that can be renal in its nature exists
in Limulus. In its general position and relations it is probably
homologous with the green gland of the Decapod Crustacea, and its
homologue in the lower orders of Crustacea, which is supposed also
to be renal in its nature. It may also possibly represent the organ of
Bojanus in the Mollusca, which is said to be renal in its function. It
perhaps represents the glandular portion of the segmental organs in
worms. That so large and important a gland is an embryonic gland,
in adult life aborted and disused, is not probable, nor is there any
good reason for regarding it as analogous to the suprarenal capsule of
the vertebrates, analogues of which are said by Leydig to exist in
Paludina and Pontobdella.”

“Reasoning from their histological structure, and by exclusion, it
seems not improbable that these glands are renal in their nature and
homologous with the green glands of the normal Crustacea.”

“They seem also homologous with the organs described by M. A.
Giard in the Rhizocephala, and said by him to be ‘situated on each
side of the middle part of the animal, and generally coloured yellow
or red (primitive kidneys ?), *”

“JT may add that all these observations were made on living
Limulus Polyphemus, in the laboratory of the Anderson School of
Natural History at Penikese Island, Mass.”

NOTES AND MEMORANDA.

Browning’s Platyscopic Lens.—Mr. J. Browning has recently
produced a form of pocket lens, which he has called the platyscopic,
and which certainly for extreme flatness of field is superior to the
Codrington or any other lens that we have seen. We have given it
careful trial ere expressing our opinion, and we consider that while
lower in power it possesses advantages which make it, par eacellence,
the first in the field. It is a triple achromatic combination, in which

* ‘Annals and Mag. N. H.,’ Noy. 1874, p. 383.

38 NOTES AND MEMORANDA.

the chromatic and spherical aberrations are corrected by the central
lens of dense flint. This lens is nearly three times as thick as the
crown-glass lenses. The interior curves are almost hemispheres.
The final correction for spherical aberration is made by altering the
thickness of the dense flint-glass lens. The three lenses are united
by a transparent cement which has a refractive index corresponding
very nearly with the glass. This prevents light being lost by re-
flexion from the surface of the deep curves. High-power Stanhope or
Codrington lenses are only suitable for the examination of transparent
objects. The Platyscopic Lens focusses about three times as far from
the object as the Stanhope or Codrington lenses. This allows opaque
objects to be examined easily, as light can be conveniently allowed to
fall upon them at any required angle.

Lactate of Silver as a Colouring Agent.—It seems that M.
Alferow * advocates the use of the lactate of silver instead of the
nitrate. He recommends a solution of one part in eight hundred of
distilled water, with the addition of a few drops of a concentrated
solution of lactic acid. The presence of the free acid renders pre-
cipitation less easy, and the only formations that occur are the
chloride and albuminate of silver. The formation of several disturb-
ing precipitates is thus avoided. Alferow asserts that the pictures
are much clearer than those obtained ‘by the nitrate, and that the
lactate, if applied to the mesentery of the living frog, interferes less
with the circulation. It may be mentioned that this author denies
the existence of stomata in blood-vessels and serous membranes,
and states that solid particles traverse epithelial layers between the
cells, which move to give them passage by some mechanism not yet
understood.

Silica Films and the Structure of Diatoms.—Mr. G. W. More-
house has been following out the line of investigations begun some
time ago by our Secretary, Mr. H. J. Slack. In a paper read before
the Memphis (U.S.A.) Microscopical Society, at one of its summer
meetings, the writer remarked that he had prepared some films of
silica, after the process described by Mr. H. J. Slack.t “To facilitate
examination, some of the films were carefully washed and then
mounted in balsam; others were burned out upon the glass cover
before mounting. The latter method is much the best and quickest.
The opinion of so distinguished an observer as Mr. Slack is entitled
to great weight, and the writer is happy to be able to concur with him
in the opinion that the cellular character of some of the films is due
to bubbles of gas; and that, under the conditions to which these
experiments are necessarily confined, the deposition of the silica is
generally in the form of spherules. No one pretends that these con-
ditions approximate to those that obtain in the growth of the protec-
tive covering of the living diatom; yet, in a kind of unexplained
general way, the experiments upon these artificial films are supposed
by some to strengthen the ‘ bead theory,’ although the conditions

* © Archives de Physiologie,’ Nos. 4 and 5, 1874.
+ ‘Monthly Microscopical Journal,’ June 1, 1874, p. 238.

NOTES AND MEMORANDA. 39

under which the spherules are formed probably differ as decidedly
from those surrounding the growth of the diatom, as does the manu-
facture of shot from a natural formation of lead. As has been shown
by Mr. Slack, a very slight change in the conditions of the experi-
ments is often followed by a difference in the character of the films
produced.” After some further observations the writer advances to
describe the different preparations of diatoms examined by him:

Coscinodiscus occulus tridis. Best illumination, at a north window,
from white clouds. The specimen very large, and the two plates
separated. The inside layer perforated with circular openings; no
film detected. The plate is thickest on the border of the openings,
and the hexagonal network of the outside plate lies in the depressions
between and everywhere around these thickenings of the inside plate.
The outside plate is furnished with a thin film over each hexagonal
areola, with a fine angular branching network extending out from
the coarse hexagonal ridges into the films to strengthen them, and is
coarsest nearest the ridges, and is very fine, or, in some cases, entirely
diaphanous in the central parts of the areole. The film is seen per-
fectly along the line of fracture, which always passes through the
depressions. The thick portion next the holes, in the inside plate
described above, occasionally extends beyond the line of fracture,
owing to its greater strength. Distinct shadows of the sides of the
hexagous are observed as the mirror is thrown to one side or the
other.*

Aulacodiscus Samensis. Structure the same as Coscinodiscus.

Terpsine Americana and T. musica. The structure of both the
same. A distinct angular open network, porous almost like a sponge.
As the objective is lowered the outside markings gradually become
indistinct, as the lower and finer ones of the same general character
come into focus.

Epithemia Hyndmannii, S. and E. turgida. An outside plate with
hexagonal depressions and network, strengthened by internal trans-
verse ribs. It breaks through the depressions and leaves well-marked
projecting points.

Campylodiscus. The various species of this genus are seen with
perforated plates and the line of fracture running through the
holes.

Trinacria regina. Perforated plate, with fracture through the
holes.

Cymbella. Very large members of this genus, observed in hundreds
of specimens, with structure resembling grating, and fracturing
through the depressions, leaving the points of the grating distinctly
projecting.

Gomphonema geminatum. This shell is very instructive, for the
ribs radiate and branch, diminishing in strength toward the margin in
the best way to make the shell strong and light. The line of fracture
runs through the so-called beads in any direction.

Stauroneis Stodderii. A peculiarly and very strongly marked shell.

* Compare with the careful and very accurate observations of Mr. J. W.
Stephenson, ‘ Monthly Microscopical Journal,’ vol. x., p. 1.

40 CORRESPONDENCE.

It has coarse longitudinal ridges and furrows, and, it seems, slightly
radiating transverse ridges passing over and across the longitudinal
ones and through the furrows.

Erratum in Professor Abbe’s Paper.—Owing to a printer’s error,
the word swm in the 19th line of p. 193 in the October number has
been placed instead of sine, which it should have been. The word
sum in the preceding line is a mere surplusage. We may state also
that Dr. Fripp had nothing to do with either the reduction or repro-
duction of the article in these pages.

CORRESPONDENCE.

RESOLUTION OF AMPHIPLEURA PELLUCIDA.
To the Editor of the ‘Monthly Microscopical Journal.

Wayanp, N.Y., October 23, 1875.

Str,—That Amphipleura pellucida is “ dotted” or “beaded” can
no longer be doubted. It was so seen by Mr. J. Edwards Smith,
of Ashtabula, Ohio, and the observations published in the ‘ Lens’
(Chicago) for April, 1873. The objective used was a Tolles’ 5th.
I had at nearly the same time, and independently, reached the same
result with a Tolles’ ;4th immersion (see ‘ American Naturalist’
for May, 1873). In the ‘ Boston Journal of Chemistry’ for June,
1875, Samuel Wells, Esq., of Boston, confirms these observations,
using a Powell and Lealand jth and a Tolles’ }th and th. And
now Messrs. Dallinger and Drysdale, in the ‘ Monthly Microseopical
Journal’ for September, 1875, announce the same result, obtained
with a Powell and Lealand }th. Witnesses enough,

A word as to objectives of medium angle of aperture. Some
microscopists seem to have the impression, both in England (recent
discussions in this Journal) and in America (‘ Popular Science
Monthly, New York, November, 1875), that such glasses, of good
quality, can only be obtained from Germany and France. But the
principal makers of England and America can make, and some of
them, at least, have been making this class of objectives when re-
quired, of proportionate merit with their higher-angle immersion
lenses. Recognizing the fact that no one glass can be adapted to
‘all grades of work, they undertake to meet the requirements of
those interested in any department of microscopic study. As a case
in point, I have a Tolles’ jth inch, dry, of 70° angle of aperture,
with cover adjustment, costing $26.00 U.S. currency. After allow-
ing for depreciation of paper currency, this is about 41. 12s, (In
comparing prices with those of foreign makers, duty, exchange, &c.,
would be cozsidered.) This lens has a tapering front, permitting the
use of a bull’s-eye condenser on opaque objects, and has sufficient

CORRESPONDENCE. 4]

working distance to resolve the Pleurosigma angulatum, through a
thick slide turned over. With the slides right side up, and rising
up to j-inch eye-piece, x 1600; I resolve the angulatum either dry
or in balsam, and show both sets of lines of Navicula rhomboides
distinctly, Stawroneis phenicenteron is resolved without resorting to
oblique light. On Surirella gemma I get the transverse lines strong,
but the longitudinal are faint and unsatisfactory to one accustomed
to the complete resolution into hexagons got by objectives of higher
angle. On the whole, it is a very useful glass, but cannot take the
place of the immersion objectives of high angle on one side, nor of
4-inch to 32-inch objectives on the other.

The above work with the }th was all done without the aid of
Mr. Wenham’s Reflex Dluminator,—a very important aid in resolving
lined tests, whether used as originally intended by the inventor, on
dry mounts, with object in contact with the slide; or, as pointed out
by Samuel Wells, Esq., on balsam slides, with objectives of suf-
ficiently high angle of aperture to give a bright field. The latter
method, to me, is the most serviceable of the two, for on most of my
slides the objects adhere to the cover. Out of half-a-dozen slides of
S. gemma, I was unable to find a single frustule detached. The
Reflex Illuminator makes the medium angles approach more nearly
to the former performance of the higher, but it also enables the latter
to fully maintain their superiority over the former.

Yours truly,

Gro. W. Morenovuss,
Wayland Depét, Steuben Co., New York, U.S.A.

Mr. Hicxie anp Proressor Hasert’s newes7 OBJECTIVE.
To the Editor of the ‘ Monthly Microscopical Journal.’
Liverpoon, November 5, 1875.

Srr,—I was very anxious to hear further respecting Professor
Hasert’s newest objective, having received from a friend in London
a report of what had taken place at the October meeting of the
Royal Microscopical Society respecting the above objective, and I
must confess that I felt very much disappointed when I read
Mr. Hickie’s letter in your November number, and still more so
when I heard that the objective was not exhibited, as suggested,
at the November meeting of your Society ; possibly Mr. Hickie may
not be guilty of this mishap.

It is, however, curious that after so much fuss has been made
of Hasert’s objective, when the time came for proofs the objective was
not produced!! Mr. Hickie’s letters are very interesting because
they generally contain some outlandish disclosures, such as, “ Its
performance (No. 7, Benéché’s) on S. gemma I shall leave unrecorded,
as the truth here would seem incredible.” *

=S°ME Me Ji. Nos Ixxs, p. 208:

42 CORRESPONDENCE.

“But with regard to S. gemma itself, I attach no sort of value to
this diatom ; and I have often wondered how such a thing ever got
voted into a test.” *

“ Of course I used no condenser. I have always regarded that
article, when employed on high-power delicate tests, as a mere opti-
cian’s booby-trap. Its only use there is to disguise the optician’s
faulty workmanship and to make a bad glass pass muster for a good
one.” f

“Indeed, I seem to myself never to have known what the word
definition really meant till I saw this glass (Hasert’s), so beautifully
clear, sharp, and distinct were all the details. I certainly never saw
any objective that even approached it! ” t

After extracting the above from Mr. Hickie’s correspondence, I
do not think it necessary to trouble your readers with any comments
on Mr. Hickie’s statements, but I may just be permitted to add that,
although I do not doubt for a moment that Mr. Hickie may be a very
good mathematician, a very accurate draughtsman, or an excellent
German scholar, I do not consider his skill as a manipulator of high
powers to be such as he wishes the microscopical world to believe ;
and when next in London, Mr. Hickie will, perhaps, display before
the Royal Microscopical Society some of his extraordinary feats of
manipulative skill, giving thus a proof which will certainly be much
more convincing than the reports of Mr. H. P. Steadman § and
Mr. J. R. Leifchild. |

As to Mr. Leifchild, I know him personally: he may be a good
geologist, mathematician, or anything else, but as a judge of the
performance of high powers and of the resolution of difficult tests, I
can only say that I very much doubt whether he has ever worked
with an objective of less than half an inch focal length, or resolved
P. formosum !! ited

I have just heard from an authority who saw the celebrated
Hasert’s objective, in London, that its performance is nothing like
what it is reported to be ; and it appears to me that we, as English-
men, ought to be more careful in setting afloat reports which, when
once spread, will certainly damage the credit of the makers of the
jinest object-glasses in the world—the English.

Some time since Mr. Hickie caused a similarly startling sensation
with Benéché’s improved No. 7 objective, and the straight candle-light.
Thave seen three of these improved objectives and compared them with
similar powers by Beck, Hartnack, Powell and Lealand, and Ross—the
result being always that Benéché’s objectives were found “ moderately
bad,” and would not accomplish the feats announced by Mr. Hickie,
not only in my hands but also in those of some well-known micro-
scopists; this bad or inferior performance may have been caused
either by our lacking Mr. Hickie’s extraordinary manipulative skill—
or, rather, by the inferior quality of Benéché’s objectives.

; * ‘M.M.J.,’ No. lxxii., p. 290; vide also No. Ixxvi., p. 175 (Mr. Leifchild’s
etter).

t Ibid., No Ixxix., p. 33. t Ibid., No. lxxxiii., p. 263.
§ Ibid., No. Ixxii., p. 291. || Ibid., No. Ixxvi., p. 175.

CORRESPONDENCE. 43

Mr. Hickie does not seem to believe in anything else but German
objectives. I very much doubt if he has ever looked through some
of the fine Powell and Lealand’s objectives (we know he does not
approve of their eye-pieces), above all those made on their new
formula? !!

What feats would Mr. Hickie accomplish should he use Powell
and Lealand’s finest objectives, and their achromatic condenser ?

Perhaps he might succeed in superseding the performance of his
German object-glasses, and his straight candle-light, and favour us
with some more of his startling discoveries! ! !

I am, Sir, your obedient servant,
M. J. Gorpon.

Proressor Hasrert’s New Ossecttve.
To the Editor of the * Monthly Microscopical Journal.’

19, MonTPELIER PLAcE, Bricuton, November 10, 1875.

Srr,—Your readers will peruse with interest Mr. Hickie’s report
on the glass above referred to.

Whatever else it may do, this new glass seems calculated to cause
a reconsideration of some views very generally current. For in-
stance, Mr. Hickie, speaking of its definition, gives it his unqualified
admiration; and says, “I seem to myself never to have known what
the word definition really meant till I saw this glass, so beautifully
clear, sharp, and distinct were all the details. I certainly never saw
any objective that even approached it.”

And yet it appears that the lens will not bear deep eye-piecing!
Indeed its conduct in this respect, according to Mr. Hickie’s account,
though not in his words, is nothing less than very bad.

But if there is one thoroughly accepted idea connected with
lenses, it is that deep eye-piecing is, above all, the surest test of their
correction. So that we have here a contradiction. Mr. Hickie ex-
plains by saying that he “ came to the conclusion that there is ample
room for improvement in our eye-pieces.” No doubt; but whatever
their demerits, they are as fair a test for one lens as for another
of like power; and the fact remains that this Hasert objective, though
it defines with extraordinary precision, bears deep eye-pieces much
worse than the general run of glasses,

The facts relating to the screw-collar are very remarkable ; but
under the circumstances, I cannot think with Mr. Hickie that the
absence of that apparatus will be an insuperable objection in England ;
besides, if these glasses are really good enough to induce English
opticians to make them, they will no doubt be furnished with screw-
collars, to meet extreme cases; a great advantage, though everybody
will appreciate the comfort of not being ordinarily obliged to use
them.

On the subject of penetration, working histologists will be very
disappointed in the vagueness of Mr. Hickie’s report; hence I beg

44 CORRESPONDENCE.

permission to ask him for information as to what tissues were
examined, their thickness, how prepared, in what media mounted,
what structures were seen in them, how defined, and to what depth
were they well seen ?

If Mr. Hickie will be so good as to inform us upon these points,
and any others that may occur to him, I am sure he will confer a
favour upon all who, like myself, are looking forward anxiously to
improvements in physiological glasses.

I am, Sir, faithfully yours,

R. BRanweE.u.

A New Secrion Buape.
To the Editor of the ‘ Monthly Microscopical Journal,’

Ba.timoreg, Mp., November 14, 1875.

Str,—The qualities required in a section useful for microscopic
research are even thinness pushed as far as tissue structure demands,
and smooth surfaces, the production of a perfect knife edge. This
last is urged forward in slicing fashion, whether a holder be employed
or not; but in all cases personal equation varies or jeopardizes the
result, and the student’s end can be attained then only when this
element of failure or inconstancy shall have been minimized.

Wherefore it occurred to me to have recourse to an eacentric
knife, and I devised in the month of June last the blade which I
employ. It resembles the chisel of a plane, but its edge forms the
are of a circle of 23 inches radius, of which the centre is above and to
the left of the axis of revolution; consequently it works excen-
trically in a sweeping course, whether it be used directly upon the
glass table of the holder, or lifted from it by a very thin polished
steel washer.

The dimensions are as follow: thickness } inch, width 21 inches,
length 31 inches. It is flat beneath, but is ground away above to a
thin edge on the cutting side, and on the upper surface is a removable
button for grinding. Below the centre of the are of the cutting edge
is the excentric hole through which passes the pin that also per-
forates the glass table of the holder, and upon which it revolves.
When the blade is in place, a small washer and a short open spring
are to be slid on the pivot over it, and lastly a screw with a milled
head to make all tight. Now by withdrawing the knife to the left,
the lower edge just clears the margin of the aperture for paraffin,
but as the blade descends to the right, its edge traverses the whole of
the aperture, with which its construction corresponds.

With this arrangement it is easy to flood the object under
treatment.

I have also used a very thin steel washer, 12 inch radius, under the
blade, so that its cutting side can never be dulled by débris upon the
glass plate.

The aperture of the cylinder in the holder is seven-eighths of

CORRESPONDENCE. 45

an inch, which is traversed by the moving knife from heel to point,
and with so gentle a sway that perfect sections are readily made.
With this microtome I have produced sections as large as the
cylinder would allow, especially of nerve matter; but it answers just
as well for other tissues if properly prepared for cutting, an indis-
pensable condition.
CurIsTOPHER JoHNstTon, M.D.

CHROMATIC AND SPHERICAL ABERRATION DISTINCT.
To the Editor of the ‘ Monthly Microscopical Journal.’

16, Firzroy Squarn, W., November 20, 1875.

Str,—I fail to perceive what benefit can result to science from an
endeavour to confound two things known by distinct characteristics,
and designated by different terms: it tends (as it appears to me) to
meddle with, and muddle, rather than to elucidate scientific nomen-
clature. I allude to a paper in your last issue by Dr. Royston-
Pigott, “ On the Identical Characters of Chromatic and Spherical
Aberration.” Aberration is I take it—as its derivation implies—<a
straying away from.” Spherical aberration is a straying away from
the focus of rays not very near the axis of the pencil reflected, or of
homogeneous rays refracted, at a spherical surface; and chromatic
aberration is the straying away of all other rays from the focus of
rays of any given colour, in consequence of their unequal refrangibility.

Dr. Pigott states that the spherical aberration of a homogeneous
pencil “is for convenience called chromatic aberration:” to this
statement I must entirely demur. In the succeeding paragraph he
is startled by the statement that all chromatic aberration does not
involve spherical aberration. In a lens with proper elliptic surfaces
(if it could be constructed) there would be chromatic but no spherical
aberration; and Sir J. Herschel (I think) has given a formula by
which the spherical aberration of a lens may be corrected by a
meniscus of the same glass, but the chromatic aberration would
thereby be much increased.

It is perfectly true that in all lenses chromatic and spherical
aberrations must be coexistent, because the only practicable sur-
faces are spherical; but coexistence and identity are not synonymous
terms. ;

I remain, Sir, yours faithfully,

CuarLes Brooke.

CHROMATIC AND SPHERICAL ABERRATION.
To the Editor of the ‘ Monthly Microscopical Journal,

Sir,—I have made so many attacks against Dr. Pigott’s strange
optical announcements—for such I have considered them—that I had
determined to allow his paper—the strangest of them all—concerning
chromatic and spherical aberration to rest without comment, as its
erroneous teaching must be evident to everyone whose instruction is

46 CORRESPONDENCE.

intended. Mr. Hogg having called notice to the article, I venture to
remark that chromatic and spherical aberrations are quite distinct in
their characters. It is well known to practical opticians that a tele-
scope lens can be corrected for colour, leaving nothing but the effects
of irrationality, and yet require all the curves to be remodelled, in
order to correct spherical aberration only; and a telescope when so
corrected has the front and posterior surfaces of the object-glass of
different radii. Ifthe lenses of the object-glass are reversed in the
cell, all fine definition becomes lost.

According to Dr. Pigott’s theory, so long as achromatism is ob-
tained any form of lens will suffice; but we are far from realizing
this felicitous state of things. Photographic lenses must now be
made to work visually with perfect telescopic distinctness, in order
to meet the requirements of photographers. But as the chemical
plane of distinctness is within the visual focus, the lenses have to be
very much under-corrected, and the sharpness of picture is obtained
or the spherical aberration corrected, entirely by the curvatures given
to the combination.

I am, Sir, yours obediently,

F. H. WEnuAM.

Tue Reruex Intuminator. _
To the Editor of the * Monthly Microscopical Journal.

S1r,—As you have properly intimated that your pages must now
be closed against any further discussion with Mr. Stodder in relation
to his objectives, therefore beyond what I have already recorded I
shall make no remarks.

But, as Mr. Stodder asks me a question in his second letter, I ask
permission to reply. When I stated, “ water between the front lens,”
Lappear to have omitted the words and cover. All light being thrown
on top surface of slide, at an internal angle beyond that of total
reflexion, the field is quite dark with objectives of the largest aper-
ture—not the most extreme rays of which can admit them. All
transparent objects adherent to the total reflecting surface, cause the
rays to enter—without perhaps much deviation—and the object being
irregular in surface, or internal structure, the light is arrested and
dispersed, and the minute parts rendered visible with a dark field.

If the object is mounted in Canada balsam, no such condition
exists, as the top of the cover then becomes the total reflecting surface.
If the objective is now used as an immersion, there will be no
reflexion from the cover, for the light now enters the object-glass.
But if the object is mounted dry, and lays on the slide, then the
object-glass may be used as an immersion, with a dark field, because
the cover in fact becomes nothing more than an additional thickness
of front lens, and acts optically as part of it.

I am, Sir, yours obediently,
F. H. WENnAM.

CORRESPONDENCE. 47

Mr. Mayary’s Letter.
To the Editor of the ‘ Monthly Microscopical Journal.’

Sir,—I have no intention of discussing optical questions with
Mr. Mayall. My paper referred to (which he so genteelly denies),
demonstrating a means of obtaining full apertures on immersed
objects, was contributed by me to th» ‘ Quarterly Journal of Micro-
scopical Science,’ No. 12, July 1855, page 302. It did treat only of
immersed apertures, under the title “On the Aperture of Object-
glasses in relation to Objects in Canada Balsam.”

Tn expressing his dissent against an article that he has not read,
and saying that it has “no reference to the subject,’ Mr. Mayall
commits himself to a mere blind and senseless contradiction.

The cube of glass with which my “simple demonstration” is
tried measures three inches and one-tenth square. If an object-glass,
say a 5th, is adjusted for immersion and focussed on to surface, the
disk of light observed, and then water introduced, the disk remains
the same. If the object-glass is now raised (as it should be) so as
again to meet the surface for the immersion focus, it will of course
also slightly raise the apex of the cone in the glass; but still the
increase of the angle in the distance of the cube is too small to be
detected.

Mr. Mayall takes the air angle as shown in the glass for un-
covered objects, then adjusts the lenses for immersion, and attributes
the increase of angle always thus obtained by a nearer approximation
of the lenses, to the introduction of water, or the immersion!! This
needs no comment.

Professor Stokes would perhaps think it a profitless waste of time
to wade through the wearisome length of this controversy. Mr. Mayall
imagines that he has secured him as an ally. I need not question
the Professor’s authority, but I can only say that if he shows mathe-
matically that the principles involved in my “ simple demonstration ”
are not right, I shall have no hesitation in demonstrating practically
that he is wrong.

Finally, if Mr. Mayall, or anyone that yet believes that in ordinary
immersion object-glasses, the angle in glass is increased by a water
connection between the front lens and glass surface, I shall be happy
to give a demonstration with any object-glass that he may choose to
bring. I am in town every day, with all necessary appliances at
hand, and with due notice would have all ready, so that no time
should be lost.

Iam, Sir, yours obediently,

F. H. Wevuam.

Wl. GV: _ lk

48 CORRESPONDENCE.

Tue Surr as AN Ar In Measurina APERTURE.
To the Editor of the *‘ Monthly Microscopical Journal.’

Srr,—I do not gather from Professor Keith’s communication that
in the measurement of aperture he brings forward any argument against
the use of the slit for preventing false light frome ntering the object-
glass. This light has hitherto deceived many. Let any objective be
adjusted to uncovered, so that all aberrations at this point are cor-
rected: the outer plane of the slit is then set in the focus, in the way
that I have described. The slit need not be very narrow, but is
opened out to the full extent of the field of view: it is now absolutely
correct for uncovered aperture, from which it cannot cut off any rays
coming to the focus. It may be argued, that if the object-glass is now
closed for “ covered” and tried again with the slit in the most distinct
approximate focus, that by cutting off the aberrant rays of the pencil,
as shown in Professor Keith’s diagram, Fig. 2, it should show less
aperture, but such in reality is not the case ; the aperture has increased
in the usual ratio from uncovered to covered. But of course I do not
maintain that this is correct. If immersion apertures are to be taken
with the front lens and slit immersed, the object-glass must be adjusted
for immersion and the focus brought to the plane of slit—and this way
I have always used it. The slit does cut off false light seen up to near
the impossible angle of 180°, and in no object-glass that I have yet tried
by any maker, does the immersed angle exceed 82°, but in all cases has
fallen far short of it.

As false positions have been drawn by opponents of ways to use
the slit improperly, in order to convey the impression that after having
devised the instrument I do not know how to use it rightly, I can
see no use in arguing the question. I am always ready to prove my
case by giving a demonstration ; but in America I cannot do this for
some time to come.

I am, Sir, yours obediently,

F. H. Wenuam.

Hasert’s OBsEctivEs.
To the Editor of the ‘ Monthly Microscopical Journal,

Sir,—I have good reason for believing that even Mr. Hickie’s
guarded statements with respect to Hasert’s objectives will not be
endorsed by those who are better acquainted with their perform-
ance; no one will be inclined to accept the vague and uncertain
utterance put forth, that they “are capable of performing truly
wondrous feats :” indeed, it would appear that no very exalted opinion
is entertained of Hasert’s lenses by his own countrymen.

Dr. Dippel, in lis work ‘ Das Mikroskop,’ p. 168, 1872, tells us
“that the beauty and clearness, definition, of images when viewed by
direct illumination with Hasert’s objectives, cannot be for a moment
compared with the performances of either Hartnack or Amici’s im-
mersions. ‘They are found wanting in the resolution of lined objects

CORRESPONDENCE. 49

(diatoms), and in other departments of practical microscopy, since the
working distance is extremely small.” He further warns his readers
against the pretensions put forth in advertisements to the effect that
“ Hasert has succeeded in making objectives which render the screw-
adjustment no longer necessary ;” as he (Dr. Dippel) found that this
maker’s lenses do not work through cover-glasses, which Hartnack’s
easily do. As to the mechanical work of Hasert’s newest objective,
I may say that no tyro in our English workshops would think of
turning out anything so clumsily primitive. A point of far greater
importance to microscopists is, that the lens although alleged to be
a sixteenth is a much lower power.
I remain yours, &c.,

F.R.M.S.

—_—_—___—

Mr. BRANWELL’S PROPOSED PRIZE FOR THE BEST OBJECTIVE.
To the Editor of the ‘ Monthly Microscopical Journal.’

Sir,—I regret that any words of mine should have been con-
strued by so courteous a writer as Mr. Branwell into an implication
against the integrity of the opticians. Such an implication was far
from my thoughts. Moreover, I have reason to believe the opticians
have seen nothing invidious conveyed in my allusions to them.

The persons most interested in the award of medals—the opticians
—have little respect for amateur opinions of lenses. They know the
testing of lenses to be such essentially special and difficult work —
depending so much on the training of the eye, on manipulative skill,
on judgment in the management of the illumination—that they do
not readily believe an amateur can possess the qualifications necessary
to enable him to give a valuable opinion.

The awarding of medals for objects made for sale necessarily pro-
duces an immense amount of vexation among the unsuccessful, and, in
many cases, draws a sharp line excluding them ever after from being
fairly judged on their merits. :

Mr. Branwell sets too high a value on the security of the “ unim-
peachable ability ” of the jury in the selection of the prize lens. The
past history of competitive awards, as shown at the exhibitions since
51, teems with strange incidents scarcely known except to opticians.
If he wishes to be informed of these matters, there are two sources of
information: the fortunate exhibitors, and the unfortunate. From the
former he may learn how amateur jurymen have come to the task
lacking the main qualifications valuable in the eyes of the expert ;
how, after a mass of confused hesitation, it has happened that
judgment has been pronounced in favour of qualities which the
optician knew to be of quite inferior importance,—the real points of
excellence being seldom discoverable by the amateurs, whilst in
nearly every instance they have been indebted to the opticians for
the very terms in which to express their judgments! From the
unfortunate exhibitors he may learn that however eminent may have
been the names of jurymen, that was no security for their “ unim-

E 2

50 CORRESPONDENCE.

peachable ability ”—no guarantee on which reliance could be placed
for thoroughly careful and impartial judgments being given. That
these opticians have not, as a rule, cared.to stir up this subject, is far
more owing to apprehensions of the danger of attempting to re-argue
a verdict once given, than to any sense of weakness in their basis of
complaint. What optician dares publicly call attention to such matters
when he knows that every word he utters will be viewed with suspicion,
while, on the other hand, a few condemnatory remarks from a juryman
may do him irreparable injury ?

The appointment of a jury for the purpose of deciding on the
absolutely best histological lens would amount to an attempt to force
a general agreement, and would compel opticians either to submit to
the verdict or place themselves openly in opposition to the scheme.

Here then are some of the grounds upon which I should anticipate
that medal-awarding, annually or triennially, would produce confusion
and discord among us,—would neither attain the end sought, nor in
any manner increase the scientific status of the Royal Microscopical
Society.

In the pages of the ‘ M. M. J.’ we find expressions of very diverse
opinions as to the utility of high angles of aperture ; but this diversity
exists principally with reference to lenses of less power than+. The
reconciliation of these opinions is probably only to be attained by
microscopists being provided with both high and low angled lenses.
But if we look to high-power results—those embodying the highest
magnification and finest definition, which exhibit a marked advance on
all former results—we find the most conspicuous have been produced
with high-angled lenses,—for example: Dr. Woodward’s splendid
series of photographs of Nobert’s lines, diatoms, histological objects,
&c. The advocates for low angles have the field open to them—to
exhibit any equivalent magnifications that will bear comparison with
these photographs; if they cannot do so, they must stand aside and
no longer obstruct the onward march of the construction of high
powers.

Your obedient servant,

F.R.MS.

———

Repiy to “ Criro.”
To the Editor of the ‘Monthly Microscopical Journal.’

224, Recent STREET, Lonpon, December 4, 1875.

S1r,— With reference to the luminous field obtained with certain
immersion lenses, whilst with pneumo-lenses the field is dark, when
used on a balsam-mounted object illuminated by Wenham’s Reflex
Illuminator, it should be noted that “ Crito,” in his first letter, pro-
fessed to “ perfectly account for the phenomenon” by suggesting a
difference in the angular apertures of the lenses used. In reply, I
pointed out that the apertures in the sense implied by him do not
explain the matter ; but that the true explanation is to be found in
the fact demonstrated by Dr. Woodward and Professor Keith,—that

CORRESPONDENCE. 51

immersion lenses constructed on certain formule transmit rays of greater
angle than corresponds to the maximum air-angle.

“ Crito” now offers a totally different explanation, ignoring my
criticism, apparently unconscious that he must retract his former
fallacious explanation before he is entitled to start afresh on the same
subject.

My observation, that a certain ;!,th lens, when tried by the test
of deep oculars, did not give definition beyond about one thousand
diameters, seems to have puzzled “Crito,’—he cannot realize it.
He says the answer to such a statement is “so obvious that the dis-
cussion is puerile: the initial power is greater.”

The discussion would indeed be puerile if so obvious an answer
had been effective and had escaped my notice. But “ Crito” is again
in error: it is not true that the initial, power of a ,',th is necessarily
greater than 1000 diameters. The initial power of a lens depends on
the length of optical body and on the ocular used. ;

In the list of magnifications belonging to the particular stand and
oculars (Hartnack’s) I used to determine the limit of definition in
Zeiss’s lenses, the initial power of a 5th is given as 820 diameters !
In Zeiss’s list it is given as 680.

Your obedient servant,

Joun Mayatt, jun.

Aw Antmat-Like Diatom.
To the Editor of the ‘ Monthly Microscopical Journai.’

Sir, — The diatom figured in ‘ Nature, and reproduced in the
‘M. M. J., is a Cocconeis, probably the common C. scutellum. Pseudo-
podal-like appendages are not a new discovery or peculiar to this
form. Ehrenberg gave a figure of a Surirella, S. gemma (I think in
his ‘ Infusionsthierchen ’), afterwards reproduced by Pritchard in his
third and fourth editions of the ‘ Infusoria,’ pl. xii., fig. 4, surrounded
by a fringe of stout sete. Professor Smith remarks (see Pritchard,
third edition) that he has often seen S. gemma in this condition, but
he never detected any motion in these appendages, and considers
them to be a parasitic growth.

I once found Campylodiscus clypeus with‘similar gelatinous pro-
longations attached to the margins of the frustules; when first ob-
served they were in a very vigorous condition, but after the lapse of a
few weeks the frustules gradually died and the fringe disappeared. I
do not think the growth was parasitic, but was an abnormally large
development of the mucous envelope which all diatoms secrete in a
greater or less degree. I once saw Navicula serians in series like a
Fragilaria, the frustules being held together by a mucous envelope.
This secretion is sometimes amorphous, with the diatoms scattered in
it as in Mastogloia, or it assumes a definite form, as in Schizonema
and Encyonema, in which it forms long hair-like filaments, or it is
secreted in greater quantity at one end than the other, forming stipes
as in Cocconema (I have seen this form growing vigorously without

52 CORRESPONDENCE.

the vestiges of stipes), Gomphonema, &. Mr. Wood’s discovery! !
will therefore not do much in altering the opinions of naturalists
as to the vegetable nature of the Diatomacew, and it is probable
a few years’ study of these forms will satisfy him that they are as
much vegetable as the Desmids or any other of the simpler forms of
alges.
I remain, Sir, yours, &e.,
F. Krrron.

“ MIcROSCOPICAL SCIENCE.”
To the Editor of the ‘ Monthly Microscopical Journal.’

Sir,—F.R.MLS. says, in his remarks on Mr. Branwell’s proposed
prize for the best objective, “ I remember some years ago a large
sum of money was subscribed to the ‘ Quekett Memorial Medal Fund,’
to be given at the discretion of the Council to such member of the
Society who, in the opinion of the Council, has best promoted the in-
terest of Microscopical Science.” Like Mr. Clennam, “ I want to know”
what is “microscopical science,’ and I fear until this question is
satisfactorily answered the gold medal will not be struck. Although
ashamed of my crass ignorance, I do not hesitate to attach my name
to this inquiry.

Your obedient servant,

F. Kirton.

A New Form or Freezina Microtome.
To the Editor of the ‘ Monthly Microscopical Journal.’

PENDLEBURY, MANCHESTER.

Srr,—In all the freezing microtomes hitherto described, the
requisite degree of cold is produced by the use of a freezing mixture
of ice and salt, the preparation of which is so troublesome and the
action so tedious that the method of freezing is but little used for the
examination of tissues, except in the laboratory. A freezing micro-
tome suitable for the post-mortem room, where the immediate ex-
amination of diseased tissues and morbid growths is of extreme
importance, is still a desideratum. By substituting the ether spray
for the freezing mixture as the cold-prcoducing agent, I have arranged
an apparatus in which all the advantages of the freezing method are
secured with a minimum expenditure of time and trouble.

The apparatus consists of a rectangular brass box, through which
near to one side passes a brass cylinder provided with a screw
piston, in no way differing from that of a Stirling’s section-cutter.
In the side opposite the cylinder is an aperture in which the glass
tube of an ordinary fluid atomizer is inserted. The top of the box is
closed by a brass plate hinged in the middle, so that one half forms a
lid, through which ether is introduced when the apparatus is used.
An exit tube for the vapour is provided in the side close behind the

. PROCEEDINGS ‘OF SOCIETIES. 53

cylinder ; this tube dips down into a narrow secondary chamber, in
which the razor blade is cooled previous to making a section, thus
utilizing the waste vapour. A double elastic ball for producing a
continuous current of air is attached to the atomizer; or in the
laboratory a connection may be made with the nozzle of a gas blow-
pipe. To prepare the apparatus for use, a quantity of “ Richardson’s
compound anesthetic ether” is introduced into the box; the tissue,
imbedded or not, is placed in the cylinder, and the razor blade is
placed in its chamber; by working the elastic ball for two or three
minutes the tissue is frozen sufficient for sections to be cut with the
greatest ease.

It may be objected that the line of the hinge on the stage is an
obstruction to the free play of the razor blade; in practice I have not
found any difficulty from that source. It is necessary that the points
of the atomizer should be easy of access, to admit of their being
readily cleaned, as they are apt to become choked by small foreign
bodies, dirt, &c.; for this reason the opening to the interior of the box
must be of sufficient size. The cost of the ether is but a small item;
it is sold by Robbins, of Oxford Street, at seven shillings a pint;
three drachms are sufficient in cold weather to freeze a portion of
tissue five-eighths of an inch in diameter, and by an occasional
squeeze of the india-rubber ball to keep it frozen for several minutes.

The apparatus is arranged to stand upon four firm legs, thus having
the advantage of portability, and is covered by a coat of felt and
leather to prevent conduction. It is made by Messrs, Wood and Son,
King Street, Manchester.

Yours, &e.,

Ricuarp HucuHes.

PROCEEDINGS OF SOCIETIES.

Royat Microscorican Society.

Kine’s CoLttece, December 1, 1875.

Chairman, H. C. Sorby, Esq., F.R.S., President.

The minutes of the preceding meeting were read and confirmed.

A list of donations to the Society was read by the Secretary, and
the thanks of the Society were voted to the donors.

Mr. Beck said he had a slide to present to the Society which he
thought would be of interest, being some of the ova of the Amphiuma,
which he had described at a former meeting,* and which he then
mentioned he hoped he should on a future occasion be able to get
mounted. The specimen had been injected by one of their Fellows,
Mr. Needham, and would be placed under a microscope in the room
for exhibition at the close of the meeting. It was a rare circumstance
to get the animal at all in this country, and still more rare to get one

* Nov., 1875; see ‘M. M.J.. p. 265.

54 PROCEEDINGS OF SOCIETIES.

containing ova, so that it might be regarded as an object worth a place
in the cabinet.

The thanks of the Society were voted to Mr. Beck for the present.

The Secretary said that they were very much indebted to Mr. Baker
and Mr. How, for the loan of a number of microscope lamps for use
at their Scientific Evening on the preceding Wednesday ; the thanks
of the Society were accordingly voted to those gentlemen.

_ Dr. Lawson said he had to exhibit an invention of M. Hayem,
made by M. Nachet, of Paris, and termed a Hematimétre, for the
purpose of estimating the amount of red corpuscles in the blood. It
was not strictly speaking a novel instrument, but it was new in form.
Various apparatus had from time to time been devised for the pur-
pose, but none of them were very convenient, inasmuch as they all
required several hours’ interval for the investigation, whereas the one
before the meeting was much more simple and more easily used. It
consisted in the first place of a slide having cemented to it a piece of
glass with a hole cut in it, and then reduced to a certain level so as
to have a depth of exactly one-fifth millimeter. In the eye-piece of the
instrument there was a sort of micrometer, also arranged so as to give
a view of only the space of one-fifth millimeter, the object of this being
to procure for examination exactly the volume equal to the one-fifth of a
millimeter cubed. If, however, they were to take exactly that amount of
blood for examination, they would find such an agglomeration of cor-
puscles that it would be impossible to estimate them; but for the
purpose of being able to enumerate them, M. Hayem took a gradu-
ated tube, and having measured 2 cubic millimeters of blood and
placed this in a small vessel, he measured into another vessel half a
cubic centimeter of serum, and then having put the blood into it he
stirred them up so as to make the mixture complete. He then placed
sufficient fluid from this mixture in the cavity of the slide to exactly
fill it, and put it under the microscope. ‘Then by focussing the
instrument upon it, it was possible to readily count the number of cor-
puscles in the one-fifth of a millimeter cubed. He (Dr. Lawson) had
endeavoured to count them in that way, and found the number in the
ruled space to be 142; and by multiplying this number by 125 and
then by 251 (which corresponded to the quantity of serum employed
+1) he obtained 142 x 125 x 251 = 4,455,250, as the number of
corpuscles in an ordinary cubic millimeter of blood.

Mr. Charles Brooke said that if the amount were one-fifth cubic
millimeter, then it would not do to multiply by 125, the 142 should
be in that case multiplied by 5 instead; but if a cube of one-fifth
millimeter were intended, the result as stated would be correct.

Dr. Lawson said that he had intended it to be understood as a
cube of one-fifth millimeter.

The Secretary said they had a microscope brought for exhibition
by Mr. Crouch, the peculiarity of which was that it was furnished
with an arrangement for exactly centering the stage for the particular
objective which was being used, and he called upon Mr. Crouch to
further explain the improvement to the meeting.

Mr. Crouch thought it scarcely necessary to say anything further,

PROCEEDINGS OF SOCIETIES. Shp

but would just observe that all who were in the habit of using a
concentric stage, especially with high powers, were aware how difficult
it was always to keep the object in view, in consequence of some very
slight difference between the centering of the stage and the objective ;
even a jar would sometimes alter an objective in this respect, so that
one which was perfectly true when sent out by the maker might be
thrown out by being thrown down roughly in carriage. The addition
to the microscope exhibited was designed to enable any person to
centre the stage accurately to the object he was using.

Mr. Charles Brooke thought this was a very good idea for effecting
a very useful purpose. He had frequently met with the difficulty
which it was designed to obviate, and believed it most frequently
arose from the screw not being exactly central, and in which minute
differences—far more minute than any practical mechanism could
overcome—would be enough to cause a very appreciable error in the
case of a high power. He believed that it was a circumstance which
no ingenuity could overcome, and that no centering, however carefully
arranged, would under all circumstances be found perfect.

The thanks of the meeting were voted to Mr. Crouch for bringing
the improvement before their notice.

Mr. Alfred W. Bennett read a short paper relative to certain
organs which he had observed on the leaves of Drosera and other car-
nivorous plants, and to which he had lately drawn attention in the
‘Popular Science Review.’ The subject was illustrated by numerous
preparations exhibited under the microscope. (The paper will be
found printed at p. 1.)

The President, in proposing a vote of thanks to Professor Bennett
for his communication, inquired if there was a definite relationship
observed between the characters of the tropical plants which had
these glands, and those which were allied to Drosera.

Mr. Slack said these objects were evidently quite distinct from
those which belonged to Coleus, which seemed to be only modifi-
cations of glandular hairs. In Coleus the stems on which these
glands were erected were very short, but in others, such as Lavender,
they were long stems with knobs on the top. On Coleus there was
a distinct cross, like a hot-cross-bun mark, indicating a tendency to
divide. He happened to have a slide of a piece of Digitalis leaf
from Calcutta, in which there was a complete division, forming a
cross of four cells. The internal glandular objects described by
Professor Bennett evidently had quite another function.

Mr. Bennett said he had frequently observed these structures im-
bedded in the leaf immediately beneath the tentacles. They were not
hair structures in any sense of the term.

The President called the attention of the meeting to the fact that
a post-card had been received from Germany, addressed to Mr, Hard-
wicke, saying that Herr Moller’s proposed work on the Diatomacez
would not be published.

Mr. Beck said he had also received a communication of the same
kind, and inferred that the number of subscribers for the work was
deemed insufficient, and that therefore it would not be brought out.

56 PROCEEDINGS OF SOCIETIES.

Professor Rupert Jones then read a highly interesting paper “ On
the Foraminifera, with special reference to their Variability of Form.”
The subject was illustrated by a large number of diagrams and en-
larged models in plaster, &c., as well as by an extensive collection of
mounted specimens. (The paper will appear in the next number, not
having been received by the Editor.)

The President expressed the pleasure with which he had listened
to Professor Jones, and thought there were in the paper a great many
points which claimed their attention, the principal being of course
the remarkable variability of these little organisms. He hoped this
would be experimentally tested by keeping the creatures in confine-
ment and breeding them. It really seemed almost impossible to draw
a line in any particular part of the series between the species, and one
felt it very difficult under such circumstances to say what a species
was. Occurring as they did in such immense numbers, they supplied
the opportunity of studying the many differences of form and varia-
tions from a type that were likely to occur. He presumed that no
experiments had been tried on the subject, but it appeared to him
very interesting to keep these little creatures for the purpose of such
a study if it could be done. The question of opacity of certain forms
must be due in some degree to the ultimate molecular structure of
the shells, some allowing the light to pass through more freely than
others.

Mr. C. Stewart said that amongst so large a class of bodies there
must be a great number of intermediate forms, and not only would
the forms themselves vary, but the intermediate links would constantly
vary also. With regard to. the structure and transparency of these
shells, it would be found that they polarized light in a very marked
and definite manner. All the hyaline ones showed the “ black cross”
in the clearest way, but all the porcellanous varieties showed only
a general irregular mottling, and they did not lose that appearance
by alteration of the plane of polarization, but in any position still
appeared generally mottled.

The President thought the remarks of Mr. Stewart very im-
portant, the cause of the difference observed between the two kinds
in polarized light was no doubt due to their structure. If the car-
bonate of lime were arranged in crystals all perpendicular to the
surface of curvature, that would account for the “ black cross.” The
other appearance was analogous to what would occur if the particles
were arranged in every possible direction, the one being a regular
and the other a promiscuous arrangement.

A cordial vote of thanks to Professor Jones was unanimously
carried.

The Scientific Evening, November 24, 1875.

The attendance on this occasion was very good, and from the
subjoined list it will be seen that many objects of interest were
exhibited.

The President's apparatus for measuring the exact position of
absorption bands, and which is described and figured in the December

PROCEEDINGS OF SOCIETIES. . ne

number of ‘M. M. J., attracted great attention, and was found very
easy to work.

Mr. J. Badcock: The water-net, Hydrodictyon ulriculatum.

Messrs. R. and J. Beck: The ova of Amphiuma injected, and
crystals of pure gold.

Mr. W. H. Beeby : Leaf of Sherardia arvensis.

Mr. Thomas Bolton : Melicerta tyro (Hudson).

Mr. Charles Baker: A series of objectives, from 1 inch to ,}; inch,
by Zeiss; and a new glycerine adjustment lens by Gundlach.*

Mr. Henry Crouch: A new first-class microscope, with stage and
sub-stage of new construction.

Mr. Thomas Curties showed Aulacodisci, var. sp., obtained on the
late Congo expedition by Mr. Martin, H.MLS. ‘ Spiteful.’

Mr. Fitch: Anatomy of a spider’s head.

Dr. W. J. Gray: Teeth of leech in situ.

Messrs. How: Section of chalk; fossil wood from the London
clay, showing Tylosis ; silicified wood from a chalk flint, &e.

Mr. Thomas Howse: Antheridia and Antherozoids of a moss
' (Sphagnum), and section of the stem and leaves of a moss (Poly-
trichum).

Mr. C. L. Jackson: Glands on a leaf; and the skin of the spotted
gunnel.

Mr. W. Moginie: Selected Diatomacez from the Red Sea.

Mr. 8. J. McIntire: Some curious lepidopterous scales from a
Lyccena.

Mr. J. Needham : A series of preparations illustrating the morbid
anatomy of the human liver.

Mr. Walter W. Reeves: Young of the pea-urchin, Echinocyamus
pusillus,

Mr. Thomas Shepheard sent from Chester some specimens of
Stephanosceros and Floscularia.

Mr. H. J. Slack: Inner envelope of coffee berry, with polarized
light.

. Mr. Charles Stewart: Silicious sponge (Farrea).

Mr. H. C. Sorby: His new contrivance for measuring the position
of the absorption bands in spectra.

Dr. Millar: The tongues of some insects.

Mr. J. S. Townsend: Fructification of Lygodium.

Mr. J. R. Williams: Poison-fang of cobra de capello.

Mr. Thomas C. White: Crystals of gold; and Demodew follicu-
lorum alive.

Mr. F. H. Ward: Section of umbilical cord, with connective-
tissue corpuscles; and proboscis of Cherocampa elpenor.

Mr. J. W. Stephenson : Cocconeis from Manilla, showing the
pseudopodia-like bodies (as figured in ‘M. M. J.’), stained with
hematoxylin, and mounted in gum mastic dissolved in absolute
alcohol ; Aulacodiscus from Bolivian guano, with Zeiss’s D objective,
under Stephenson’s binocular.

* Not immersion; glycerine, the correcting element, being within the com-
bination,

+ See ‘Proceedings, Dec. 1.

58 PROCEEDINGS OF SOCIETIES,

Donations to the Library and Cabinet from November 3, 1875:

From

Nature. Weekly ee OME ee oda’ GE a Be
‘Athenssum:s/ pW eelsiy ie) cites “Tes Als fis’) 3. Biine eemer Ditto.
Society of Arts Journal. Society.
Journal of the Royal United Service Institution, four. parts,

containing Delineations of some Minute Sea-surface

Animals. By Mrs. Toynbee .. .. .. .. «. «. Institution,
The Natural History of Luglena viridis. By EH. Parfitt .. Author.
Quarterly Journal of the Geological Society. No. 124 .. Society.

Observations on the Sizes and Shapes of the Red Cor-
puscles of the Blood of Vertebrates. my George «

Gulliver, FARIS: <. -- ei Author.
Bulletin de la Société Botanique ‘de France °. Society.
Transactions of the Watford Natural History Society. Vol. Ts

part 2 .. Ditto.
Proceedings of the Literary a and Philosophical Society 0 of

Liverpool, Wey a5 = “oe Ditto.
Two Slides .. os ose oa) Cou ROCRSONs Eig
One Slide (the ova of Amphiuma injected) sis (Law! se = see BLGSSgemeEE

The following gentlemen were elected Fellows of the Society :—
Lieut. Richard Benyon Croft, R.N.; John J. Hamilton, Esq. ;
C. L. Jackson, Esq.

Watrter W. Reeves,
Assist.-Secretary.

Mepicant Microscopicau Socrery.

Friday, November 19, 1875.—Dr. Pritchard, Vice-President, in
the chair.

Micro-photography.—Mr. George Giles read a paper on and ex-
hibited an instrument for quickly connecting an ordinary microscope
with an ordinary camera, and obviating the use of the heliostat (see

26).

* At the conclusion of this paper the Chairman suggested the use of
a frosted silver mirror to supply a white light.

Dr. Matthews proposed using a paraffin lamp with double flame ;
and stated that, in order to save daylight, plates need not be de-
veloped at once, but could be put aside safely for some hours if
wetted with treacle and water. The yellow colour of the specimens,
if it were requisite, might be corrected with hematoxylin.

Mr. Giles, in reply, preferred sunlight direct if it could be
obtained, and did not find the colour of the slides any drawback.

Differential warm stage.—Mr. Golding-Bird explained and ex-
hibited in action a simple form of hot stage, heated by a spirit lamp,
capable of being kept in action for any length of time, its tempera-
ture being regulated according to the condition of pieces of solid
paraffin placed on it, and on a copper tongue connected with it. He
had found it extremely useful for purposes of demonstration, and its
simplicity allowed of its being used in the wards of an hospital
when examining blood in a morbid state.*

A discussion followed, and the meeting then resolved itself into a
conversazione.

* This stage has been already described in ‘ Quarterly Microscopical Journal’
for October, 1875, and is made by Millikin, of St. Thomas Street, Southwark, 8.E.

PROCEEDINGS OF SOCIETIES. 59

QueEKeTT MicroscopicaL Civ.
Ordinary Meeting, October 22, 1875.—Dr. Matthews, F.R.M.S.,

President, in the chair.

A communication from Mr. E. Gardner was read, suggesting the
use of gum water (to which a little syrup of loaf sugar was added to
prevent cracking) in mounting Ostracoda and similar organisms.
Cells could be filled with this substance, and afterwards surrounded
with gum dammar, and so permanently preserved.

The President stated that it was intended to obtain an album for
containing the photographs of members ; which he requested might be
sent for that purpose.

Mr. Bolton, of Stourbridge, exhibited the new rotifer, Melicerta
tyro, and communicated some particulars respecting it.

Mr. B. T. Lowne gave an address “ On some Recent Views of the
Classification of the Lower Animals,” with particular reference to the
use of the terms Protozoa and Metazoa.

Ordinary Meeting, November 25, 1875.—Dr. Matthews, F.R.MLS.,
President, in the chair.

The President announced that three albums had been presented to
the club—a large one by Mr. F. W. Gay, and two smaller ones by
Mr. J. W. Goodinge, and he requested that members would forward
their photographs for insertion in them.

Mr. R. T. Lewis described some specimens of the Edelweiss, a
rare and beautiful Alpine flower, which he had mounted for the
cabinet of the club.

Mr. B. T. Lowne gave an interesting account of the various re-
searches which had been made by Mr. Darwin and others into the
nature of Insectivorous plants. :

Mr. T. Charters White read a paper, in which he treated of the
various structures likely to be seen in an ordinary section of a tooth
by the general observer. After alluding to a short paper he read
before the club four years ago on the Dental Pulp, in which he
described the dentine-forming organs or Odontoblasts, and a remem-
brance of which would help them in understanding the histological
construction of the principal portion, he proceeded to describe the
process of development in the enamel, the dentine, and cementum.

The teeth may be regarded as dermal appendages, proofs of which
fact may be seen in the teeth studding the rostrum of the saw-fish
(Pristis antiquorum), or in the spear of the narwhal, at other times
occupying the interior of the alimentary canal, as in the crustacea, and
being periodically shed with the shells of these creatures, while in
the human subject they occupy an intermediate position in this range,
and are placed only a few inches from the external surface of the
body, but partaking largely of the character of the dermal structures.
The author did not promise the members that he could furnish them
with any new facts as the result of original work, but would fairly
represent the views of such workers in this department of histology as
Sharpey, Tomes, Kélliker, and Stricker, and referred those interested
in his subject to the works written by these gentlemen. He then pro-

60 PROCEEDINGS OF SOCIETIES.

ceeded to describe in detail the formation of the enamel, the dentine,
and the cementum in a well-developed tooth, and pointed out, secondly,
the departures from this normal condition met with in these several
structures, such as the extension of the dentinal tubuli into the
enamel, the formation of globular dentine and osteo-dentine, the
hypertrophied condition of the cementum known as dental exostosis ;
the principal object of the paper being to afford information to the
young and general observer relative to the various appearances pre-
sented to his notice in examining sections of teeth.

Mempuis (U.S.A.) Microscoprcan Society.

At the regular meeting, August 19, the annual election of officers
was held, resulting in the re-election of the old board, with 8. P. Cutler,
M.D., as President, and H. F. Dod as Secretary.

The Secretary's annual report sets forth—

The Society was organized August 28, 1874, witha list of twelve
members; and during the year twenty-three others have been added,
giving an active membership of thirty-five. A thoroughly good mi-
croscope has been purchased, fitted with all needed accessories; and a
collection of several hundred valuable and interesting objects has been
accumulated. The regular meetings have always been well attended,
and their interest well maintained. The following list embraces the
most important “papers” which have been contributed during the
year: “Light and Optics,” “Some Forms of Infusorial Life,” “ Notes
on the House-fly,” “ Tolles’ New 4},th versus his Old ;1,th,” “ Dammar
as a Mounting Medium,” “ Blue Glass Illumination for Difficult Tests,”
« A Method of Mounting Insects Entire,” “ Notes on Micro-crystallo-
graphy,” “Modern Wide-angled versus: Old Low-angled Objectives,”
* On the Examination of a Certain Pathological Specimen,” “On the
Organisms in ‘ Happy Hollow’ Water,” “ Measurements of the Strize
on the Diatoms of the Probe-Platte,” “On the Preparation of Silica
Films,” “Further Remarks on Wide versus Narrow Angles,” “ Mea-
surements of Probe-Platte,’ “The Cyclops,” ‘ Plant Crystals,”
“ Preparation of Coal Sections,” “The Water Flea,” “Silica Films
and their Bearing on the Structure of Diatoms,’ most of which have
been published in the journals of this country or England. Many
minor articles have also been presented. The Society’s indebtedness
to its corresponding members for their valuable aid was most heartily
acknowledged.

On ballot, C. B. Johnson, M.D., of Providence, and Ed. Wheeler,
Esq., of London, were elected corresponding members. Valuable
contributions of prepared objects were received from Dr. C. B. John-
son and Mr. Henry Mills, for all which a vote of thanks was passed.

The President’s annual address was then read, after which the
Society adjourned to first Thursday in September.

ee ae ey ee NN
. iN A ‘

The Monthly Microscopical Journal, FebY1 1876.

*

WWeat & Lith

THE

MONTHLY MICROSCOPICAL JOURNAL.

FEBRUARY 1, 1876.

I.—Remarks on the Foraminifera, with especial reference to their
Variability of Form, illustrated by the Cristellarians.
By Professor T. Rupert Jonus, F.R.S., F.G.S.

(Read before the Royau MicroscopicaL Society, December 1, 1875.)
Puates CXXVIIL, CXXIX.

CoNnTENTS.
Introduction.
Systematic grouping of the Foraminifera.
Shells of the Imperforata.
Shells of the Arenacea.
Shells of the Perforate or Hyaline Foraminifera.
The Hyaline Foraminifera.
Lagenida.
Lagena.
Nodosaria, @histellaria: Ke.
Cristellar ide: a.
Gradations of the Cristellaridea.
Conclusion.
Remarks on the Cristellarians figured in Plates CX XVIII. and CX XIX,
in illustration of their Variability.
Introduction.—This paper is not intended to be exhaustive; and,
with little that is novel, it aims at giving a general view of the
structure and affinities of the Foraminifera and of their extreme
variability.
As is well known to Microscopists, foraminiferal shells can’ be
obtained from numerous marine sands, silts, muds, and clays, recent

DESCRIPTION OF PLATES CXXVIII. AND CXXIX.

Pirate CXXVIII.

Fic. 1—Max von Hantken’s ‘Die Fauna der Clavulina-Szaboi-Schichten,’ 1875,
p- 23, pl. 2, fig. 5 (part). Nodosaria Beyrichi, Neuyeb.* (= Nod. radi-
cula, Lin.). a, side; 6, end, with radiate terminal orifice.

2.—v. Hantken. p- 29, pl. 3 f. 14 (part). Dentalina soluta, Reuss.

3.—y. Hantken, p. 45, pl. 4, f 12 (part). Marginulina pediformis,
Bornemann.

», 4.—v. Hantken, p. 46, pl. 5, f. 9 (part). Marginulina subbullata, Hanthk.

3.—Y. Hantken, p- 58, pl. 7, f. 1 (part). Robulina Budensis, Huntk.

6.—yv. Hantken, p. 87, pl. 4, f. 11. Marginulina splendens, Hantk. a, side;
6, inner edge.

(Fie. 7.

* “Nodosaria Neugeboreni, Reuss,” in the explanation of the Plate,
VOL. XV. F

62 Transactions of the Royal Microscopical Society.

and fossil, by careful manipulation, and very easily from the
sponges of commerce, which often become charged with them when
trodden about, in process of drying, on richly foraminiferal beaches.
Sometimes half the material of a beach-sand consists of Foramini-
fera. In some tropical islands, shoals and beaches are formed
wholly of the shells of Orbitolites, Tinoporus, Operculina, &c.
Fresh seaweeds placed in salt-water aquaria, fresh oyster-ooze and
other marine muds washed in sea-water, fine surface-nets and
under-water trailing bags, are among the means of obtaining
living specimens. In the fossil state Foraminifera constitute great
stratified masses, such as the Fusulina limestone of Russia and else-
where, the Saccamminal limestone of Northumberland, much of the
White Chalk, the Nummulitic limestone of Europe, Asia, and North
Africa, the Miliolitic limestone of Paris, Alveolina limestone of

Fic, 7.—y. Hantken, p. 87, pl. 14, f. 4. Cristellaria elegans, Hantk. a, side;
b, inner edge.

» 8.—y. Hantken, p. 49, pl. 5, f. 11. Cristellaria Schwageri, Hantk. a, side;
b, inner edge.

» 9.—yv. Hantken, p. 53, pl. 5, f. 6. Cristellaria areuata, D’Orb. a, side;
6, inner edge.

», 10.—v. Hantken, p. 49, pl. 5, f. 3. Cristellaria eymboides, D’ Orb. (= Planu-
laria crepidula, F.and M.). a, side; 5, inner edge.

», 11.—v. Hantken, p. 51, pl. 6, f. 44. Cristellaria nummulitica, Giimb. a, side;
6, inner edge.

», 12.—v. Hantken, p. 56, pl. 6, f. 7. Robulina Kubinyii, Hantk. a, side;
b, inner edge.

3, 13.—A. D’Orbigny’s ‘ Foraminiféres fossiles du Bassin tertiaire de Vienne,’
1846, p. 102, pl. 4, f. 27. Robulina simplex, D’Orb. (= Cristellaria
rotulata, Lamarck).

» 14.—y. Hantken, p. 57, pl. 6, £11. Robulina limbosa, Reuss (= Cristellaria
cultrata, De Montfort). a, side; b, inner edge.

» 15.—D’Orbigny, ‘For. foss. Vien., p. 91, pl. 4, f. 4. Cristellaria cassis,
F. and MM.

is pupae ee ‘For. foss. Vien.,’ p. 99, pl. 4, f. 18. Robulina calcar,

inné.

;, 17.—vy. Hantken, p. 58, pl. 14, f. 9. Robulina Baconiea, Hanthk.

» 18.—y. Hantken, p. 53, pl. 5, f. 7. Cristellaria Kochi, Reuss. a, side;
b, inner edge.

» 19.—v. Hantken, p. 54, pl. 13, f. 20. Cristellaria galeata, Reuss. a, side;

b, inner edge.
20.—y. Hantken, p. 53, pl. 5, f. 5a. Cristellaria arcuata, D’Orb. (= Sara-
cenaria Italica, Defrance). a, side; 6, inner edge.
» 21.—y. Hantken, p. 53, pl. 5, f. 56. Cristellaria areuata, D’Orb, (= Sara-
cenaria Italica, Defr.). a, side; b, inner edge.
», 22.—a, b, O. Terquem’s ‘ Troisieme Mémoire sur les Foraminiféres du Systeme
oolithique,’ 1870, pl. 23, f. 7. Frondicularia dentaliniformis, Terq.
(= Linguline form of Frondicularia papa, D’Orb.).
23.—Terquem, pl. 22, f. 22. Frondicularia irregularis, Terg. (= Lingulina
carinata, D’Orb., Modele, No. 26).
», 24.—Terquem, pl. 22, f.10. Frondicularia spissa, Terg.
» 25.—Terquem, pl. 24, f. 15. Flabellina ponderosa, Zerg.
», 26.—Terquem, pl. 23, f. 26. Flabellina triquetra, Terg.
» 27.—H. B. Brady’s ‘Synopsis of the Foraminifera of the Middle and Upper
Lias of Somersetshire,’ 1867, p. 110, pl. 2, f. 25. Planularia pauperata,
Jones and Parker,

TheMonthly Microscopical Journal, Feb? 1876

Remarks on the Foraminifera. By Prof. T. Rupert Jones. 63

Scinde, Loftusia rock of Persia, Orbitoidal limestones of the Alps,
India, Alabama, Jamaica, and Java, and Amphistegina limestone of
Australia; besides vastly adding to the bulk of other limestones
and many thick clays, and further, by means of their glauconitic
casts, to that of numerous sandy and other strata. Some of the
oldest rocks even are largely composed of them, in the forms of
Hozoon,* Stromatopora,t Receptaculites,t and their allies.

Some kinds of Orbulina, Globigerina, and Pulvinulina have
been taken by towing nets at and near the surface of the ocean by
Major Owen and others. These constitute also the mass of the
abyssal forms. They may have more sarcode in proportion to shell

PLATE CXXIX,

Fic. 1a.—Von Hantken, p. 24, pl. 3, f. 1 (part). Nodosaria spinicosta, D' Orb.

», 16.—v. Hantken, p. 37, pl. 4, f. 2. Dentalina Hoernesi, Hanth.

» 2.—v. Hantken, p. 48, pl. 5, f. 2 (part). Marginulina Behmi, Reuss.

», 3.—v. Hantken, p. 48, pl. 14, f. 6. Marginulina Behmi, Reuss.

» 4.—v. Hantken, p. 53, pl. 6, f. 3 (part). Cristellaria fragaria, Giimb.

» 90.—v. Hantken, p. 51, pl. 5, f. 10. Cristellaria arcuata, Pail. a, side;
6, inner edge.

», §6.—y. Hantken, p. 57, pl. 6, f.10. Robulina gutticostata, Giimb. (= Cristel-
laria papillosa, F, and M.). a, side; 6, inner edge.

», 7.—v. Hantken, p. 57, pl. 14, f. 15. Robulina granulata, Hantk.

» 8.—y. Hantken, p. 28, pk 2, f 10. Nodosaria Budensis, Hantk. (= Nodosaria
raphanus, Lin.). a, side; 6, end.

» 9— Annals Nat. Hist.,’ ser. 4, vol. viii. “Nomenclature of the Fora-
minifera,” by Parker, Jones, and Brady; ‘Species founded by
D’Orbigny on figures in Soldani’s ‘ Testaceographia,’ &e.,” 1871, p. 163,
pl. 10, f. 72. Marginulina raphanus, D’ Orb.

» 10.—D’Orbigny’s ‘ Foram. foss. Vienne, p. 95, pl. 4, f. 8, 9. Robulina
ariminensis, D’Orb. (= Cristellaria costata, ¥, and M., var.). a, side;
b, inner edge.

» 11.—D’Orbigny’s ‘For. foss. Vien.,’_p. 62, pl. 3, f. 1-3. Lingulina costata,
D Orb, a, side; 6, edge; c, end, with terminal, flexuous, slit-like
orifice.

12.—Brady’s ‘ Foram. Lias,’ p. 112, pl. 3, f. 43. Cristellaria costata, D’ Orb,
(non F. and M.), keelless subvariety.
», 13.—Brady’s ‘ Woram. Lias,’ p. 110, pl. 2, f. 30. Planularia Bronni, Rémer.
», 14.—Brady’s ‘ Foram. Lias,’ p. 111, pl. 2, f.33. Planularia reticulata, Cornuel.
(= Vaginulina).
», 15.—D’Orbigny’s ‘ For. foss. Vien.,’ p. 90, pl. 3, f. 43. Cristellaria semiluna,
D Orb. (= Planilaria auris, Defr.).
» 16.— Ann. N. Hist.,’ 1871, p. 166, pl. 10, f. 75. Planularia rostrata, D’ Orb.
», 17.—v. Hantken, p. 43, pl. 13, f. 13. Flabellina striata, Hantk. a, side;
b, edge.
18.—‘ Ann. N. Hist.” 1871, p. 243, pl. 11, f. 101 (part). Cristellaria navi-
cularis, De Montf. (= Flabelline Cristellaria cassis, F, and M.).
» 19.—D’Orbigny’s ‘ For, foss. Vienne,’ p. 104, pl. 5, f. 5. Robulina imperatoria,
D Orb. (= Cristellaria vortex, F, and M., keeled).

* Dawson’s ‘ The Dawn of Life,’ 8vo, 1875. Hodder and Co., London.

+ G. Lindstrom, ‘Kongl. Svenska Vetenskaps Akademiens Handlingar, vol.
ix., No. 6, 1870.

{ Gumbel, ‘Transact. Bavarian Acad.’ Munich, 1875.

F 2

64 Transactions of the Royal Micrescopical Society.

than the others. Like as the few butterflies rising up to
the mountain top, have left the many floating in air among
the flowers in the valley, so these float upwards in the higher
regions of the water, whilst others remain below,—making their
tests of deep-sea sand or of spicula, or of Foraminifera themselves,—
or attached to rock, shell, or seaweed,—or lying free on the bottom,
with other organisms, to be preyed on by Dentaliwm (8. P. Wood-
ward) or Ophiwra (at 1260 fathoms, Wallich),—to be used up in
the shells of some larger congeners,—to be accumulated in strata,
—or to be converted into such glauconite as coats the floor of the
Mexican Gulf with black-green sand.

The differences of depth at which these Microzoa live, and the
concomitant conditions of agitation or repose, of clear or muddy
water, much or little nourishment, of relative warmth and lght,
are easily recognizable. Thus Polystomella has a thicker shell in
shallow than in deep water; but Globigerina is thicker in deep than
in shallow; and where it most abounds in abyssal waters, the
associated Foraminifera are often few in kind, few as individuals,
and very small. Possibly the greater amount of light and warmth
that the shallow-water Polystomellx and the floating Globigerinz
enjoy, favours their growth beyond that of the more deeply seated
and the non-floating forms; but others living even in deep water
have thick sheils, either meeting with favourable conditions of
growth, or having grown thick before they sank to the bottom.

The susceptibility of variation, by relative increase of size, or
hy modification of shape and mode of growth, or by the thickening
and complexity of the shell, belongs to all the systematized groups
of Foraminifera.

Systematic Grouping of Foraminifera.—There are said to be
4000 recognizably different forms of these little Rhizopodal shells,
such as a “superticial observer can separate by words and a name ”
(Hooker), and these have been sorted according to their apparent
alliances into the several divisions of the appended Table (pages
89-92), copied by permission, with slight modifications, from
Henfrey and Griffith’s ‘ Micrographical Dictionary,’ new edition, 8vo,
Van Voorst, London, 1875. These groupings are based, primarily,
on the texture of the shell (whether “ porcellanous,” “hyaline,” or
“sandy ”), and secondarily on the arrangement of the segments of
sarcode, and the form of the shell-chambers. Neither the fixed
(parasitic) habit of shell, nor the single-chambered condition, has
weight in this classification, as neither is confined to any one group
of the Foraminifera.

Arranged on this plan many dissimilar forms are found to be
mutual allies, and even more closely akin; whilst, with some, an
external resemblance, chiefly from mode of growth, is mimetic.
only,—or, rather, a real bond of relationship, arising from the

Remarks on the Foraminifera. By Prof. T. Rupert Jones. 65

general kinship pervading the whole Foraminiferal family. Nor
does relationship end here; for there are among these Rhizopods
structures and habits analogous to, if not identical with, those of
other Protozoa. Thus the spicular contents of Carpenteria, Poly-
trema, and Stromatocerium (if not accidental), and the internal
structure of some old fossil Patelline (Orbitolinw) and Dactylo-
poride, point towards Sponges ; whilst the radial shells of Calcarina
and Tinoporus, and the basket-like or pierced shells of others not
so well known,* remind us of Polycystina, though the material be
different. Nor should we forget that the Porcellana, protruding
their sarcode from one part only of the body, are, 7m so much,
more closely allied with their shell-less representatives, than with the
Hyalina and those Rhizopods which have sarcodic processes from
the general surface. At the same time we know that it is difficult
to define the relative value of pseudopodial characters, which do
not coincide with the absence or the development of those more
important organs, the “ Nucleus” and “Contracting Vesicle,” on
which Dr. Wallich has based a natural system of classification.+
No evidence of either organ having been found in Foraminifera
and Polycystina, they stand (as Herpnemata) low in the scale of
Rhizopods. <A definite nucleus is present in the Protodermata,
comprising the Plagiacanthide, Acanthometrina, Thalassicollina,
and Dactyochidz, leading towards Spongide. Both nucleus and
contracting vesicle characterize the Proteina, as defined by Wallich,
comprising the Actinophryna (Actinophrys, Gromia, Lagynis, &c.),
and Amebina (Ameba, Difflugia, Arcella, &c.), and leading to
Infusoria.

A new link between the Foraminifera and the Polycystina
appears to be indicated in the following extract from one of Dr.
Wyville Thomson’s Reports on the ‘ Challenger’ Expedition.t Off
Japan, geing eastward (long. 167° E., lat. 35° N.], and before
turning south towards Honolulu, “on the 26th of June, we sounded
in 2800 fathoms. Several forms were met with [in the towing nets
below the surface] which apparently do not occur on the surface,
particularly a number of species of a group which is, so far as we
know, entirely undescribed. It seems to be intermediate between
the Radiolarians and the Foraminifera, resembling the former in
the condition and appearance of the sarcode and in the siliceous com-
position of the test, and the latter in external form.” The broken
tests were extremely abundant in the red clay of the bottom. §

* Such as a fenestrated, lageniform, porcellanous Foraminifer, discovered by
M. Vanden Broeck, of Brussels, and the pierced Rotalines noticed by Ehrenberg

and Joseph Wright. See ‘ Proceed. Belfast Nat. Field Club,’ ser. 2, vol. i., p. 87.
+ ‘Annals Nat. Hist.,” June 1863, p. 439; ‘Monthly Microscopical Journal,’
1865, &e.
t ‘Nature,’ November 25, 1875, vol. xiii., p. 70.
§ See also ‘ Proceed. Roy. Soc.,’ vol. xxiv., p. 35.

66 Transactions of the Royal Microscopical Society.

If the perforated Rotaline figured by Ehrenberg and Joseph
Wright should prove to be siliceous (as mdeed the Antrim speci-
men is, though possibly from pseudomorphic change), we have
already noticed analogous intermediate examples.* Ehrenberg’s
original Spirillina vivipara is described as bemg sélzceous; and is
a perfect analogue of our common Spirilline. Possibly some of
the common small Microzoa, passing for Foraminifera, under the
microscope, with transmitted light, are really siliceous, and require
careful examination with the polariscope.

“JT should rather infer,’ wrote Professor W. C. Williamson, in
1858, “ that the hard shells of the Foraminifera do not constitute a
sufficiently constant and important element in their organization
to justify our trusting to them as guides in the discrimination of
species ;” and others since then have fully agreed with him, almost,
if not quite, to the extent of regarding not only the Forami-
nifera, but even “the entire group of the Rhizopoda,” incapable of
specific division.t Still the shells have their zoological meaning ;
for, being variously formed by the sarcode, they refer to some
processes of life and some habits of body, some peculiarities of
individuals and races, which in higher and more complex animals
give specific characters,{ but here, unaccompanied by other fixed
features of superadded parts, lose their distinctiveness among imi-
tative repetitions, and are thus lost in changes due to the general
adaptability of the sarcodic creature to the varied conditions of its
watery life. Certain as it is that the shells cannot supply grounds
for specific distinction, yet their texture and form have the impress
of the vital actions of an organism of which frequently little else is
tangible; and hence they are important elements in grouping the
Foraminifera. It is difficult to appreciate the physiological value
of such apparent or presumed organization as is met with in the
soft parts of these Protozoa, alive or dead, under the microscope,
even when well seen; it is difficult to adjudge the relative value
of the several methods of producing and using the pseudopodial or
otber extensions of sarcode; their modes of existence, their indi-
vidual development and growth, are very imperfectly known. ‘The
differences in function and habit and mode ot growth may be quite
fixed in the several groups of individuals, or not: if fixed, they
give specific characters ; if interchangeable, whether by stages, by

* See ‘Proc. Belfast Nat. Hist. Field Club,’ ser. 2, vol. i., pp. 87, 88.

+ Williamson, ‘Recent Brit. Foram.,’ p. x.

+ Professor W. C. Williamson says, “Such differences in the chemical and
histological composition of these shells probably indicate correlate physiological
differences in the living sarcode, or secreting animal substance, thet have at least
a specific value” (‘Recent Brit. Foram.,’ p. xii.). The same form of shell (as
in Cornuspira, Trochammina, and Spirillinu, for instance) being represented in the
three groups (Imperforate, Arenaceous, and Perforate), should not invalidate
the a for specific distinction unless the structural differences fail to hold
good,

Remarks on the Foraminifera. By Prof. T. Rupert Jones. 67

alternations, or less regularly, there is no special grouping. Obser-
vations can now be multiplied in these directions, with the help of
good aquaria, towards the knowledge of Rhizopodal life.

Shells of the Imperforata.—In the opaque shells of the Miliolida
(see Table), an important group of the Porcellana or Imperforata,
there is only one outlet for the sarcode, whether as pseudopodia, or
sarcoblasts (Wallich), or as a stolon with new segmental growth.
The simplest forms of their adult shells are either a mere cell-like
shell (Squamulina), or a discoidal spiral tube (Cornuspira). A
similar coil forms the commencement of some Miliolx, which enlarge
with half-turns of tubular shell (investing a wire-like sarcode,
pinched at the bends), on one or three planes.* By growing out
straight, after having made a few of the alternate-sided (agathis-
tegian) turns, the shell becomes a Ceratospirulina, linking Miliola
with Vertebralina.

The tooth-like process, or obsolete septum, in the aperture, is
sometimes bifid; and by extending as a cribriform plate it becomes
the distinguishing feature of Hawerina. The inward extension of
this oral network, as labyrinthic structure, characterizes Quinquelo-
culina saworum and Fabularia. Another modification of the
Porcellana is seen in the forms typified by Orbiculina and Pene-
voplis, towards which some flat, wide-spread Hauerine seem to
lead us, whilst Fabularia and Alveolina have a similar internal
structure. Further, a Sprroloculina (from the Orbitoidal limestone
of Java) is figured by Ehrenberg,{ which “is very interesting in
having lateral stolons from segment to segment, showing a pro-
lepsis of the more complicated and closely related Orbitolites, the
outside of the quasi-annular segments being multistoloniferous.
These supernumerary stolons begin by few, and become many
in later segments.” {

Dr. Carpenter states:§ “I have lately come into possession,
through the kindness of M. Munier-Chalmas, of the Sorbonne
Museum, of a new fossil type of Foraminiferal structure belonging
to the Orbiculine group, in which a partial coalescence (or sub-
division) of chamberlets, like that of the lamellar portion of Hozoon,
is very distinctly marked, so as to establish precisely the link of
connection which was wanting between the chambers of Peneroplis
and the completely divided chamberlets of Orbiculina.”

* See Williamson’s ‘ Rec. Brit. Foram.,’ &e, 1858; and W. K. Parker, “On
Miliola,” ‘Trans. Microscop. Soce.,’ new ser., vol. vi., p. 53. Here I take the
opportunity of stating that for facts and views given in this paper I am largely
indebted to my friend Prof. W. K. Parker, F.R.S., with whom I have had the
pleasure of working on the Foraminifera for twenty years.

+ ‘Transact. R. Acad. Berlin’ (for 1855), 1856, pl. 4, fig. xx.

t ‘ Annals Nat. Hist., Oct. 1872, p. 265.

§ ‘Annals Nat. Hist.,’ ser. 4, vol, xiii., p. 467.

68 Transactions of the Royal Microscopical Society.

The now nearly extinct Dactyloporidz are far less evidently
allied to the other Porcellana above mentioned, than the latter
are amongst themselves. Their simplest form of shell (Haplo-
porella), however, consists of little sacs, or bottle-shaped chambers,
repeated in lateral apposition; and in more complex forms there
is a structure approaching that in old Orbetolites.

In these points, besides the similarity of shell-tissue, the several
groups of the Porcellana approach one another ; but the Dactylo-
poride seem to stand somewhat apart, wanting links, hidden, per-
haps lost, in the older rocks. The high-class “hyaline” Thalamo-
pora reminds us of some features in the structure of Dactylopora.

Shells of the Arenacea—The Foraminifera arenacea divide
themselves at first sight into three sets:—1. Those which always
have a sandy shell (Lituola, Trochammina, &c.); 2. Those which
have a partly perforate and partly sandy shell (Valvulina) ; and 3.
Those which are clear in the young and sandy in the old stages, as
Teatularia and Bulimina, and sometimes Spiroloculina, Quinque-
loculina, and Nubecularia.

The persistently arenaceous forms are also divisible into two
kinds:—1. Those with fine-grained sand in the shell-cement, and
mostly smooth (Trochammina, &c.); and 2. Those with coarser
grains, less cement, and a rough surface (Litwola, &c.). In some
cases sponge-spicules are partly or wholly used in the construction
of these tests. There is great difficulty, however, among the innu-
merable modifications of the arenaceous Foraminifers, in drawing a
line between relative roughness and smoothness of shell, abundance
and scarcity of cement, and coarseness and fineness of materials ;
and we are led from the rough lituate, to the smoother nautiloid
Lituole, and on to the rotalioid Trochammine, and thence to
Valvulina, until the whole series becomes apparently indivisible.*

Of the rough-cast sand-shells, with a minimum of cement,
Lituola is the leading type. It takes the well-known lituate shape ;
but frequently also it imitates Lagena, Nodosaria, Orthocerina,
Marginulina, Flabellina, Bulimina (?), Nonionina, and Globigerina
so closely that, excepting for its internal labyrinthic structure and
cribrate septa, the sandy coat would seem to belong as rightfully
to these as a hyaline shell. My friend, Mr. H. B. Brady, F-.B.S.,
tells me, indeed, that it is very difficult to say whether or no the
earliest (paleeozoic) Nodosariz had normally clear, or opaque, or
sandy shells.

In his description of Quinqueloculina fusea,t Mr. H. B. Brady,
F.R.S., points out that it differs from Q. agglutinans t im haying a
tough, flexible test with a very little amount of calcareous or earthy

* Brady, ‘Annals Nat. Hist.,’ ser. 4, vol. x., p. 261.

t+ ‘Annals Nat. Hist.,’ ser. 4, vol. vi., pp. 276, 286.
$ Op. cit., p. 48.

Remarks on the Foraminifera. By Prof. T. Rupert Jones. 69

constituents, although still of composite structure. Like Globigerina
and Orbulina, this Miliola becomes less calcareous, he remarks, in
brackish water. In similar degree, but under marine conditions,
Trochammina is less arenaceous than Lituola.

Dr. Wallich * remarks on the difference‘in test-structure between
the coarse-shelled Diéfjlugia and the chitonous Arcella, being only
of subspeczfie value, at most, in these Proteima, which he places
much higher among the Rhizopods than the Herpnematous Fora-
minifera.

My friend Mr. H. B. Brady, F.R.S., states, in a letter dated
December 25, 1875:

“ T think I have satisfactorily settled that the dentaliniform Foraminifera from
the Carboniferous rocks were all non-porous (‘ imperforate ’),—that those from the
Permian were partly true Dentaline (at Byer’s Quarry) and partly imperforate
(at Tunstall Hill); the specimens in the latter case are larger and have much
thicker shells. Many Paleozoic forms (not Dentaline) are quite thin-shelled, and,
to all appearance, imperforate—neither ‘porcellanous’ nor truly ‘ arenaceous.’
Endothyra is another case in point,—thin-shelled, never porous, and subarenaceous.
I believe some of these forms are really and truly the commencement of two series,
differentiating, on one side, into a porous (perforate),—on the other, into a truly
arenaceous (imperforate) line of organisms, The Carboniferous Valvulina is an
analogous, smooth, imperforate species.

“ Involutina (Liassic) has sometimes a perforate undershell, though arenaceous
externally. I have some specimens beautifully perforate, but not one in a hundred
of those I have worked upon. I am convinced that it runs into Zrochammina
incerta without any gap, though distinct enough in the tuberculate thickened
forms. Indeed, the key to the relationship between the Arenaceous and the Per-
forate forms is to be found in the genera Zrochammina, Valvulina, Endothyra, and
Textularia, The labyrinthie condition of some Textularie links them with the
Lituole.”

On the Abrohlos Bank occur Valvuline with coarse-grained
shells, and’ others of the usual fine-grained consistence. Whether
the coarser specimens are Lituol# imitating Valvulina, or really
Valvuline with unusually coarse shells, losing their customary
hyaline tissue altogether, it is difficult to say. So, on the con-
trary, as the older (fossil) Bulimine and Textulariz are sandy
(Ataxophragmiwm and Plecanium, of Von Reuss), it may be sur-
mised that they were at first either persistently sandy and Lituoline
forms, or at most only partially “hyaline,” as Valvulina t is now;
and that they have since produced more and more hyaline shell
(less and less sandy), until their successors have ceased to take up
sandy materials until arriving at an adult or old stage.

Of the two gigantic arenaceous Foraminifera, Parkeria and
Loftusia, it is stated that the latter, elongate and biconical,
shelled with calcareous cement and fine sand-grains, has a similar
relationship to Alveolina and Fusulina that Trochammina incerta

* ¢ Annals Nat. Hist.,’ March 1864.
+ Some of the Cretaceous Vu/yu/ing are quite Buliminoid in aspect.

70 Transactions of the Royal Microscopical Society.

has to Cornuspira and Spirillina.* With its great size, it has
considerable labyrinthic extension of its shell walls within, as in
Intuola. The great spherical Parkeria is sandy with little cement,
and, beyond the nucleus of earliest chambers, its walls (highly
labyrinthic and Lituoline) are quite concentric and enclosing, un-
like any other known Foraminifer. f

In Valvulina we have a linking between the Perforata and
the Imperforata; and if Valvulina leads to Trochammina and
Webbina, and if these, when poor in sand-grains, are but little
distinguished from Nubecularia, Cornuspira, and Miliola (most
of which also can at times take up sand into their shellsubstance),
there are evidently several points where the differentiation -of the
three great Foraminiferal groups is by no means absolute.

Shells of the Perforate or Hyaline Foraminifera—The
globular, subglobular, lageniform, and other primordial segments,
whether simple, or divided off into a secondary semilune, are seen
in the Imperforata, Arenacea, and Perforata. The straight, linear,
or “stichostegian” growth of segments occurs in all the three
groups, though rare in the first, where it is represented only by
some attenuate Articuline and Spiroline, with obsolete Milioline or
Peneroplid commencements. In the second and third groups it is
common, as in Litwole and Nodosarix. It often occurs too as a
“sport,” or wild growth, after other segmental arrangements,
giving rise to “dimorphous” Miliolew, Peneroplides, Cristellarie,
Polymorphine, Virguline, and Textularizx. Both Lituola and
Nodosaria (theoretically straight, but often bent), are so changeable
that dimorphism of curved and straight (lituate), or of square-
ness and roundness, in the same individual, is not unfrequent. The
only analogous freedom from the restraint of a regular fixed line
of growth among the Globigerinida is enjoyed by Planorbulina,
especially in its Truncatuline modifications; but here a single
straight line is never attained. The heaping up of chambers and
chamberlets, as in Orbitoides, Patellina, Hozoon, and others of the
Globigerinida, is not here in question.

The existence of “canal-system” and “intermediate skeleton ”
is characteristic of the higher Rotalina, but it has been discovered
in Planorbulina by M. Munier-Chalmas.{

The simple, tubular, coiled Cornuspira, Trochammina (T. in-
certa), and Spirillina are scarcely distinguishable except by their
shell-texture ; and though some fossil (Jurassic) Cornuspire and
Trochammine are so thin, and in the latter case so free from sand,
as to be subtranslucent, their habit of growth distinguishes them ;
whilst Spirillina is always perforate.

Alveolina, Loftusia, and Fusulina represent, in the three several

* H.B. Brady, ‘Phil. Trans,,’ 1869, pp. 741 and 751.

+ Carpenter, op. cit., p. 728.
¢ ‘Annals Nat. Hist.,’ ser. 4, vol. xiii., p. 459, note.

Remarks on the Foraminifera. By Prof. T. Rupert Jones. 71

groups, a similar form of shell, but with considerable differences of
structure.

The “agathistegian” growth of shell, so characteristic of Miliola,
is represented in the Perforata by Allomorphina and Chilostomella,
and among the sandy forms by Trochammina milioloides. On the
other hand, the nautiloid, or disco-spiral, segmented growth, so
characteristic of the Perforata, is found in Lituola (L. nautiloidea
and L. canariensis), Hndothyra, and Trochammina (T. inflata)
of the sandy group ; but it is only approached in the Imperforata
by Hauerina and Dendritina. 'The Orbiculinida (porcellanous)
correspond, in annular and subdivided chambers, with Hetero-
stegina, Cycloclypeus, &c. (hyaline).

The alternate arrangement of chambers, seen so frequently in
the Hyalina, is less common (Valvulina) in the Arenacea (unless
we include the sandy Teatularie and Buliminz), and does not
appear among the Porcellana.

Thus we see some general features of resemblance between all
the three great groups, in the style of growth and arrangement
of the segments, as represented by the shell; and occasionally still
more binding links, such as the passage from the Perforate through
Valvulina and its arenaceous allies to the Imperforate group. We
also see very close kinship between some of the so-called “ families,”
and decidedly among the members (so-called “ genera”) of these
subgroups, though we have here looked at only those of the Por-
cellana and Arenacea, and that very cursorily. It is well known
that the distinctive naming of the members of the so-called
“ genera” of Foraminifera almost amounts in some cases to naming
the individuals themselves; and that “subgenera,” “species,”
“subspecies,” and “ varieties ” are terms easily applied to specimens
differing less and less from a chosen type, the characters of which
exist for us only in the shape, ornament, and other features of a
simple shell. Doubtless the real zoological distinctions (whatever
their relative value may be) are to be found in the morphology
of these Microzoa: doubtless also their shells have the impress of
their original and successional conditions, but these characters are
obscured to a very great extent, and wait for further elucidation.

The following extract from a memoir by my friend Prof.
W. K. Parker and myself, in the ‘Quart. Journ. Geol. Soc.,’
vol. xvi, 1860, pp. 293, 294, expresses the views on this subject
we then entertained, and which we still hold, looking, however, on
“species” of Foraminifera as more comprehensive, and less easily
defined, the more exact our acquaintance with them becomes.

“ With respect to the nomenclature adopted in our Table (of fossil and recent
Foraminifera of the Mediterranean and Euxine areas, /oc. cit., p. 302), we have, in the
first place, been careful to eliminate all unnecessary binomial terms, such as dupli-

cate names, or names given to but slightly varied individuals; and at the same time
we have enumerated many well-marked varieties in each species, because of their

72 Transactions of the Royal Microscopical Society.

value as indications of peculiar conditions of habitat; and because, many of them
presenting at first sight striking differences of form, size, and ornamentation,
and being easily mistaken for types of distinct specific groups, they have acquired
an importance in the eyes of zoologist and geologist which makes it convenient to
give them a sort of subspecific value and a binomial term.

“Tt has been doubted by some whether in this, the most variable, because
simplest, family of the animal kingdom, every variety should not be distinguished
by its own binomial appellation,—a plan that has been followed almost to the
full by many naturalists. In this, however, we cannot agree, for the unlimited
multiplication of quasi-specific names, linked together by pseudo-generic titles,
can only weary the catalogue-maker, and throw obstacles in the way of the syste-
matist; for it keeps up a false notion of the value of external characters which are
rarely essential, whilst no clue is thereby obtained to the morphological law of
each real specific type. Evidences of such Jaw, however, are not wanting when
we carefully examine varietal forms as they diverge, and, as it were, radiate, from
a given central type.

“Though Linnzeus was somewhat parsimonious in giving names to the micro-
scopic shells which he knew, and though Fichtel and Moll partially indicated
their great variability, and were cautious in naming them, yet it was not until
Dujardin demonstrated the nature of the Rhizopodous sarcode and its simple,
non-differentiated character, and until Williamson and Carpenter, taking up the
study of certain species, showed what extreme forms might be connected together
by innumerable gentle intermediate gradations, that anything like a really
scientific appreciation of these Microzoa may be said to have existed. Our own
experience of the wide limits within which any specific group of the Foraminifera
multiply their varietal forms, related by some peculiar conditions of growth and
ornamentation, has led us to concur fully with those who regard nearly every
species of Foraminifera as capable of adapting itself, with endless modifications
of form and structure, to very different habitats in brackish and in salt water,—
in the several zones of shallow, deep, and abyssal seas,—and under every climate,
from the poles to the Equator. Our principles of nomenclature, and the applica-
tion of them, may be seen in our papers on Foraminifera in the ‘ Annals and Mag.
Nat. Hist.’ ”

Hyaline or. Perforate Foraminifera.—The typical shell of a
“hyaline” or “ perforate” Foraminifer 1s, in its simplest form, a
very thin, calcareous, perforated tissue, as in an Orbulina, or in
a young Globigerina, or in the primary segments of a Nummulina.
In the Lagenida this early shell is more compact than in some
other groups, but still minutely perforate. With the growth of
additional segments (whether in straight, curved, or alternate
arrangement), the chambers become coated, by the investing sar-
code, with successive layers of shell; and the primary layer,
whether soft and friable, or relatively hard and glassy, becomes
thickened ; its perforations, however, are usually kept continuous
with the tubules in the succeeding layers by the presence of the
pseudopodia, between and around which the little prism-like consti-
tuents of the simple shell are formed. According to the number
of successional layers, the chamberwalls necessarily vary in thick-
ness, either uniformly or with imequalities.

These latter originate variously; for instance, 1. From the
superabundant shellmatter laid down on spots or lines, as pimples
and prickles, or as thick and thin ridges, as in the Lagenda.
2. Thickenings over certain structures, as over the edges of septa,

Remarks on the Foraminifera. By Prof. T. Rupert Jones. 73

as in Cristellaria, &c., and of margins, as in Vaginulina, &c.
(“limbation’’) ; or over the crossing of septa, as in scabrous Num-
muline, and in umbonate Amphistegine ; also in the umbilicus
of Rotalia. 38. Local hypertrophy of the shellsubstance, with
. branching tubes, continued from the annular and other canals, in
the thicker shells; as in the radiate processes of Tinoporus, in
the umbones of Polystomella, and in the processes and umbones
of Calearina. 4. The-outward extension of the narrow walls, or
intervallation, of the tubuli, making their edges sharp and rugged,
as in old Globigerinx, and even prolonging them into thickets
of long, thin needles, as in the acerose and hispid Globigerinz and
Orbuline, rivalling Fadiolaria in their radiate growth. Other
modifications of this superficial shellgrowth among the pseudopodia
are seen in some Planorbulinew; and the shellmatter sometimes
sheaths the roots of the pseudopodia in very hirsute Calearinz, also
occasionally in Textularza and Planorbulina. In an extreme degree
it involves the terminal processes of sarcode in Polymorphina
horrida; and not unfrequently makes an apertural tube, giving a
pouting orifice to Uvigerina, &c. 5. The formation of subsidiary
flaps, tentlike projections, and chamberlets for umbilical sarcode, is
frequent, as in asterigerine Discorbinz. Such secondary segments
are neatly packed among the chambers in Amphistegina.*

Endless modifications of external appearances are brought about
by the various developments of these and other habits of growth;
and the eatremes produced by each kind of growth may seem at
first sight to have little or no relation one to another.

The method in which the shelly coatings of successive segments
meet each other,—singly, in the simple tentlike setting-on of the
new chamber ; doubly, with more or less continuous enwrapping of
the new segment in shellmatter; or double with intermediate
canaliferous substance,—does not now immediately concern us,
though at the foundation of many modifications of form.

Lagenida.—The Cristellarians, whose variability we have
especially to illustrate, belong to the Lagenida. This large group
comprises, besides El/ipsoidina, of obscure relationship, the Lagenz,
the Nodosarine, and Orthocerine. Polymorphine and Uvigerine
have very little distinctive character to separate them from this group.

Lagena.—The very common Lagenz are mere flasklike shells,
exquisitely delicate, presenting endless and generally elegant modifi-
cations of form. Always of simple construction, Lagena, nevertheless,
has its surface occasionally beset with rough granules of shellmatter,
and even overcast with a coating t which the outer sarcode may be
said to have laid down in abortive effort to procure the “ supplemental

* The examples here offered for these inequalities of surface are not to be
regarded as exhaustive.
+ ‘Phil. Trans.,’ vol. clv., p. 420, pl. 18, fig. 7.

74 Transactions of the Royal Microscopical Society.
skeleton’ so highly perfected in some Rotalina. When elliptical
in section (compressed) Lagenz lose the roundness of their orifice,
which becomes a slit, giving the quasi-subgeneric name of Fisswrina.
The triangular and quadrangular forms of some compressed Lagene
have given rise to other such terms. Amphorina is a Lagena open at
both ends. When the apertural tube is turned inwards, the shell is
Entosolenian ; when the tube is present and protrudes as usual, it is
Ectosolenian. Some Polymorphine have an inverted tube also.
The shells of Polymorphina and Uvigerina have much in common,
one with another, and consist essentially of Lagenoid chambers
heaped alternately, with certain habits of growth, but Lagenidal in
ornament and aperture. Nor are Bulimina and its subgroups far
removed from the same series.

Nodosaria, Cristellaria, &e.—A succession of Lagenoid cham-
bers, in a straight line, constitutes a Nodosaria. ‘The chambers
being like a series of bottomless, or at least perforated, flasks, set
one on another. They differ considerably in their overlap, from
merely encircling the previous apertural tube, or neck, to investing
the whole front of the previous chamber. The terminal aperture
is either a round hole, with its border cut up into minute radial
lamine, or a produced tube, sometimes lipped, and occasionally en-
circled, as in some Lagene, with a little spiral cord. The ornament
consists essentially of either perfect or intermittent ridges of vitreous
shellmatter, rarely joined by cross lines; often produced into
prickles, or dying away in granules; sometimes represented by
diffused granulation, and sometimes reduced to very few sharp
crestlike ribs. Slight excentricity of the axis of growth, in the
setting-on of the segments, often takes place, simply curving the
shell (especially when it does not begin with a strong growth of
relatively large and equal-sized chambers), without altering the
relative position of the aperture: but this is easily shifted to one side,
generally the outer or convex side of the curve, and the chambers
become more or less oblique. ‘“ Dentalina” comprises both conditions
in these usually tapering, bent Nodosarina. ‘There is no straight
Nodosaria without its more or less bent congeners; and these are
associated with more and more curved individuals (Dentaline),
until the early chambers are not only excentric in growth, but
have a discoidal coil (Marginulinx); and other associates have
gone further in this style of growth, until the whole of their shell
is nautiloid (Cristellarta). Thus the smooth Nodosaria radicula
has Dentalina communis, Marginulina subarcuatula and Cris-
tellaria rotulata as its congeneric associates or varieties ; whilst the
ornamented Nodosaria raphanus, has D. acicula, M. raphanus, and
Cr. costata as varietal associates. N. radicula and N. raphanus,
moreover, are so closely linked by graduated individuals, that they
are really but varieties of one species of Nodosarina.

Remarks on the Foraminifera. By Prof. T. Rupert Jones. 75

As Lagena, so Nodosaria occurs in a compressed form, and is
then known as Lingulina ; and this bent and partially coiled is
Lingulinopsis. A Lingula much outspread on each side, by the
overreaching of the chambers, in stretching backwards, becomes a
Frondicularia; and if this has an excentric or coiled beginning
it is a Flabellina, which, without the backward lateral stretch of
its later chambers, would be a simple flat Oristellaria (Planularia).
If a Frondicularia ceases to have outspread chambers, and grows on
as a Nodosaria, it is Amphimorphina.

A flattened Dentalina, with oblique chambers, is Vaginulina ;
and if the aperture be a rift along the front of the chamber, instead
of a round hole at the margin, it is Rimulina; and a Vaginulina
with coiled commencement is either nearly or quite a Marginulina,
which without its straighter portion is a Cristellaria.

Trigonal or quadrilateral Nodosarix, known as Orthocerine,
usually have a thick shell; but some take on a Nodosarian or Denta-
line growth in advanced age, and are then termed Dentalinopsis.
Their relationship is indicated by this style of growth; Cristellariz,
Marginuline, and Vaginuline have the same habit.

Infinite gradations of form connect the “ genera” and “ sub-
genera” enumerated above; and the same habit of ornamentation
obtains throughout, namely, ridges and riblets, often broken up
into prickles, or dying away in granules. In the subdiscoidal
and the nautiloid forms a marginal, and often a single dorsal,
crest is the reduced, or concentrated, representative of the ridge
ornament. ‘The thickening of the septal edges, and of the um-
bones, is frequent and extremely variable. Lastly, the relative
size and proportion of the segments (and consequently their shape
in coiled shells) produce some of the greatest differences in the
aspect of Nodosarine and especially Cristellarian shells. This
variability in the size of the chambers in closely allied individuals
seems to rest on the peculiar habits of the animal,—its well- or
il-fed condition, its freedom of growth, and such like; and, if the
chambered segments are specially connected with the reproductive
processes,* other reasons for relative difference of size may exist;
but the gradational conditions are such as to preclude any idea of
the proportional size of chamber being a specific character.

Cristellaridea—The many “trivial” names and _ binomial
appellations given to Cristellarians (as indeed to all other con-
generic Foraminifera) have been sore troubles to the cataloguist,
though of some little use to the collector, and even to the paleon-
tologist, in recognizing the individual kinds of Microzoa, which
differ so much in external appearance. In reducing’ them, however,
to zoological order, to which mere external aspect is not the chief

* As Mr. Carter suggests for Operculina, Annals Nat. Hist.,’ ser. 4, vol. xiv.,
1875, p. 423.
VOL. XV. G

76 Transactions of the Royal Microscopical Society.

guide, such a multiplicity of names is a stumbling-block, or at least
useless. How the Cristellarians have fared in books, the following
Table will show, and at the same time it will help us to fix the few
rightful names which the chief varieties can claim, and whereby
they may be referred to as recognized typical forms. By “ Cristel-
larians” I mean the more or less coiled varieties of Nodosarina
raphanus (taking that as the type species), and admitting a limited
use of binomial appellations for these varieties.

In the following Table of the bibliography of the Oristellaridea
from the time of Linné to 1841, a great number of the most
important recent and fossil forms of this group are noticed. The
range of selected forms takes us from well-developed Marginuline
to Planularizw. Multitudes, however, of weak or merely Dentaline
Marginuline are passed unnoticed. The “ Robulina” of authors
is merged with Cristellaria on account of the interchangeableness
of the character of aperture in nearly all the nautiloid varieties ;
as may be seen in some of the best figures given by D’Orbigny,
Reuss, and others, the two kinds of aperture are merged in one.
Indeed, Dr. Carpenter has of late years found that both the round,
radiate aperture and the triangular orifice exist together in some
Cristellarix from the deep Atlantic. 3

Gradations of the Cristellaridea.—Taking up the partially
coiled Nodosarine (Marginuline), leading from Nodosaria to Cris-
tellaria, we find that Marginulina Webbiana, D’Orb., Cristellaria
subarcuatula (W. and J.), and Cr. gibba, D’O., are examples of
such gradation of form. Various specimens with different degrees
of ornamentation have been figured, described, and named. Cr.
rotulata is the simple, completely discoidal form. Smooth, it is
lxvigatula (W. and J.); subumbonate, depressula (Montagu) ;
limbate and umbonate, guerelans (De M.); limbate and tuberculate,
tuberculata and elegans, D’O. With but few chambers (necessarily
triangular), and limbate, it is virgata, D’O. If thick and opening
out transversely it becomes Italica, Defr., navicula, D’O., &c.,
and is liable like others to grow on straightwise and become
elongate.

If the simple Cristellaria has a marginal ridge, keel, or crest,
it is cultrata (De M.); large-chambered and umbonate, cassidata
(De M.); limbate with beads (or granulate on the septa), papdllosa
(F. and M.). If swollen, cultrata becomes acutawricularis (F. and
M.), a large and keeled Italica. If the cultrate form has many
small chambers, it is carinata, D’O.; if the many chambers be
much curved and rather vorticial, we have D’Orbigny’s (Robulina)
Soldanii (his Crist. Soldanii is a smooth, limbate cassis); if the
chambers be very close set, falciform, and vorticial, we have vortea
(Ff. and M.), and orbicularis and imperatoria, D’O., according to the
amount of keel and umbones. When the Cristellaria retains the

By Prof. T. Rupert Jones. 77

Remarks on the Foraminifera.

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Transactions of the Royal Microscopical Society.

80

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By Prof. T. Rupert Jones. 81

Remarks on the Foraminifera.

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By Prof. T. Rupert Jones. 83

Remarks on the Foraminifera.

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Transactions of the Royal Microscopical Society.

84

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Remarks on the Foraminifera. By Prof. T. Rupert Jones. 85

longitudinal ribbing of Nod. raphanus, we have the thick costata
(F. and M.), and the weaker ariminensis, D’O. In C. ornata,
D’O., this ornament is dying out.

An excessive crest, accompanied with thinness (compression) of
the chambers, gives rise to the large and elegant Crest. cassis and
its subvarieties.

When the keel is subdivided into spines, like the rowels of a
spur, cultrata becomes calcar (Lin.); and margaritacea, rosacea,
rostrata, and marginata are among the names given to subvarieties.
Granules on umbones and septa, or all over, are frequent in the
subvarieties of C. calear and C. cassis.

Some of the above-mentioned features and conditions are evi-
dently gradational ; the others are related by many similar grada-
tions not here mentioned, but some of which are indicated in the
Table.

The long, flat Cristellari, retaining something of the Marginu-
line growth, but with the posterior or downward angle of the
chambers reaching almost or quite down to the excentric umbilicus,
are known as Planularix, very delicate and pretty shells. Pl.
crepidula (F'. and M.) is little more than a Marginulina and rather
less than a Cristellaria of the rotulata group, but thin and im-
perfectly coiled; its modifications are endless; when keeled, it is
elongata, D’O.; rostrata, D’O., when mucronate also. With bolder
convexity and better development of the apertural margin, with
more numerous and neater chambers, and some trace of costate
ornament, we have Pl. awris,* Defrance, and its smaller forms
cymba and auricula, D’O.

Conclusion.— Without having exhausted the subject, I think
that these remarks may be usefully suggestive to beginners and
students. One good piece of work that promises satisfactory results
would be the careful copying and collating of all the figured forms
of each “genus” and “species” of Foraminifera, so that their
gradations and their distinctions might be seen at a glance, and the
right appellation, according to priority and worth, be awarded to
the types and subtypes. These appear to have come from very
early times, increasing their varieties under every new set of modi-
fying conditions to which they were introduced. These varieties
have sufficient fixedness to give a peculiar facies to the several local
eroups of Foraminifera, fossil or recent; and, insomuch, their chief
forms require a nomenclature for reference and identification.

The remarkable persistence of Foraminiferal types, in general
character, has been often noticed ; and their conservative tendencies,
due to their simplicity and universal adaptability, has been com-

* Batsch figured this shell, together with Frondicularia and Filabellina, calling
them all Nautilus harpa, an appropriate name, had he defined the separate form,

86 Transactions of the Royal Microscopical Society.

pared with the susceptibility of living on under very various
conditions, shown by man, the dog, &c., but, of course, the terms
of comparison are not really equal. The extreme variability of
Foraminifera, of both great groups (Porcellanous and Vitreous), is
doubtless governed by some systematic life-properties which we do
not at present recognize in their totality. A wide field for research
opens here. As far as we can see at present, as far as we understand
the nature and growth of these Microzoa, there seem to be but
relatively few links wanting to make the gradations, from one group
to another, in form and structure, so evident and so close that all
the Foraminifera might be placed in the close union of a specific
group, modified by conditions of habitat, feeding, climate, and
hereditary peculiarities of growth. But I am not yet prepared to
avow a belief in their unispecific relationship.

Remarks on the Cristellarians figured in Plates CXXVIII. and
OXXIX. in illustration of their Variability of Form and
Ornament.

Taking examples, as much as possible, from among contempo-
raneous and local groups, we have the associated forms, whether
varying from an original stock by long series of differences, in
collateral races, or showing new varieties, resulting from the
peculiar conditions of place and time.

The beautiful illustrations of Herr Max von Hantken’s Mono-
eraph* on the Foraminifera of those Tertiary strata in Central
Hungary, which he terms the “ Clavulina t Szaboi-beds,” supply us
with a fine series of variations of well-known forms from one geo-
logical deposit.

Alcide D’Orbigny’s Monograph on the Tertiary Foraminifera
of Vienna, known to all Rhizopodists, has also been applied to for
some good typical forms. Thirdly, the Liassic and Lower Oolitic
Foraminifera, with their innumerable variations of Nodosarine,
illustrated by M. O. Terquem and Mr. H. B. Brady, F.R.S., supply
us with two sets of Rhizopods living about the same time and
having similar developments.

The few figures taken from the reduced outlines of some
of Soldani’s illustrated Italian Tertiary (Pliocene) Foraminifera,
belong to forms not very far removed in time from those figured by
D’Orbigny and Von Hantken (Miocene).

Fig.1 (Pl. CXXVIIT.) is one of the simplest forms of Nodosarina
(Nodosaria proper). In Fig. 2 it is no longer quite straight, but

* From the ‘ Mittheilungen aus dem Jahrbuche der kén. ung. geologischen
Anstalt,’ vol. iv., 8vo. Budapest, 1875.

+ The term Clarvulina is here applied to the elongated Yritaxia (Reuss), or
dimorphous Verneuilina, D’Orb., allied to Clavulina communis, D’Orb,

Ttemarks on the Foraminifera.. By Prof. T. Rupert Jones, 87

is a Dentalina with excentric orifice.* In Figs. 3 and 4 it has lost
more and more of its bilateral symmetry, becoming a Marginulina ;
and its curvature becomes extreme and discoidal in Fig. 5. Here
the newest chamber is still simple, but the older part of the shell
has received a crest or keel—essentially a single, medial riblet.
Returning to the bent form of Nodosaria, in Figs. 6, 7, and 8, we
have stronger, neater, and more compact Marginuline ; the last
one with a crest. By the transverse lengthening and obliquity of
the chambers, with corresponding lateral compression, we are led to
Figs. 9, 10, and 11, which end in the flat form of elongated
Cristellaria, termed Planularia; whose close relation to the
discoidal type is beautifully shown by Fig. 12.

The coiling of early chambers (as in Fig. 7) is often succeeded,
not by linear, but by continued spiral growth (Cristellaria), leading
ultimately to Figs. 13, 14,15, and 16, with their various conditions
of keel, imbation, and umbones, and very changeable proportions
(and hence shape) of their chambers, see Pl. CXXIX., Figs. 18
and 19, besides the more ornamented forms. Fig. 17 is another
ultimate Cristellaria of the same breed; but Fig. 18 has still
an elongate shape, leading, on one hand, to the nearly discoidal,
but arrested, Fig. 19; and, on the other, to the very thick forms
(Figs. 20 and 21), which are known as Defrance’s Saracenaria
Italica.

Reterring to Fig. 1, we lose its roundness in the flatter Fig, 22
(Lingulina). The chambers, beginning to overlap at the edges in
Fig. 23, become chevron-shaped in Fig. 24 (Lrondicularia). Even
in Fig. 23, however, the early chambers are not simply linear in
growth, and this, increased in Fig. 24 to a subspiral arrange-
ment, leads through many gradations in these flat shells to a
spiral system of early chambers, as seen in Figs. 25 and 26; and
this Planularian growth remains free, without the overriding or
saddle-like chambers, in Fig. 27, essentially the same as Fig. 10
and its allies, and, excepting its relative thinness, equivalent to
Fig. 18, &. One of its ornamented colocal varieties is shown in
Pl. CXXIX., Fig. 12.

Plate CX XIX. exhibits some of the ornamented analogues of
the above-mentioned varietal forms of Nodosarina. Fig. la is a
Nodosaria with characteristic ornamental ridges, but they end
abruptly on each chamber, forming little spikes. In Fig. 1b several
small spines or prickles are produced on each ridge or riblet of the
chambers of a slightly bent (Dentaline) Nodosaria.

In Figs. 2-6 the riblets are represented by granules on some
allied Marginuline.t In some individuals (as in fig. 1, pl. 6, of
Von Hantken’s Monograph) they become gradually confined to the

* Tf the shell were flattened it would be a Vaginw/ina.
+ Marginulina Wetherellii of the London Clay is the same form.

88 Transactions of the Royal Microscopical Society.

septal lines; they are often wanting on the newer chambers of
the shell. In the further developed Cristellaria, Fig. 6, the granu-
lated septal lines continue the above-described character; and in
Fig. 7 the aspersion of shellmatter in the form of pimples or
granules over all the older portion of the shell is a character fore-
shown by the somewhat irregular granulation in some specimens of
Marginulina fragaria (Wetherelli), and in the grouped granules
on the umbo of Fig. 7. Soldani figured several highly granulate
Cristellariz of this kind.*

Fig. 8 is the common and variable Nodosaria raphanus,
with characteristic ribbing; Fig. 9 is its Marginulina, individuals
of which present gradual (though rare) passages to Cristellaria
costata (F. and M.) and its feeble representative, Fig. 10. The
flat form of N. raphanus is Lingulina ecostata, D’Orb., Fig. 11;
and its Flabellina (Fig. 17) is Fi. striata, Hantken.

Taking up Fig. 12 again, referred to above, we see its further
development in its colocal ally, Fig. 13, which may be said either
to fade away into, or to have come from, the Vaginulina, Fig. 14,
which is the flat asymmetrical, one-sided form of Nodosaria
raphanus. Fig. 15, one of the delicately elegant, flat Cristellarie
(Planulariz), is related by gradation to Fig. 11,’ &., m
Pl. CXXVIII., and wears the usual costulate ornament of the
Nodosarine. One of its extreme forms is shown in Fig. 16.

Fig. 18 is an explanate, broadly spiral Cristellaria (C. cassis,
F. and M.), putting on overriding chambers, and thus becoming
Flabellina, like Figs. 25 and 26, Pl. CXXVIII., and thousands of
similar and analogous varieties. Fig. 19, a Cristellaria, with very
narrow, curved, vorticial chambers, has been already noticed.

Besides the above selections, very many others might easily be
made. Thus, in Von Reuss’s beautiful plates of the Foraminifera of
the Westphalian Chalk,t the following might be arranged in suc-
cession :—Pl. 4, f.1; pl. 3, £6; pl. 2, £8: and pl. 1, £5; pl 5,
£6; pl. 7, £45; and pl.6, £5: also’ pli dj) Da) ope
pl. 8, £6; pl. 9,f4; pl. 10,f 3,4, 1. In Von Reuss’s Memoirt
on the ‘Tertiéren Foraminiferen-Fauna,’ &c., the following series
may be studied :—PI. 3, f. 30, 36, 33, 37, 389; pl, 4, f. 47, 49, 50,
53, 54; pl. 5, f. 59, 65. From f. 53 to pl. 5, f. 62; pl. 6, £. 68;
and pl. 8, f. 91. From f. 59 to pl. 6, f. 63, 64, and 66. Hundreds
of other gradational figures may easily be selected, but the above
are sufficient.

* See ‘ Annals Nat. Hist.,’ ser. 4, vol. viii., pl. 10 and 11, figs. 96-99, &e.
+ Sitzungsber. math.-nat. Cl.k, Akad., Wiss. Wien, vol. xl., 1860.
t Op. cit., vol. xlviii., 1863.

Remarks on the Foraminifera. By Prof. T. Rupert. Jones.

I. FORAMINIFERA IMPERFORATA VEL PORCELLANA.

I, NUBECULARIDA.

Squamulina, Schultze. Monothalamous.
Nubecularia, Defrance. Fixed.

If. Muutonima.

Vertebralina, D’Orb. Dimorphous usually.

a. Articulina, D’Orb. Dimorphous.
Cornuspira, Schultze (restricted). Monothalamous.
Miliola, Lamarck.

a. Uniloculina, D’Orb. Monothalamous.

b. Biloculina, D’Orb.

c. Triloculina, D’Orb.

d. Quinqueloculina, D’Orb.

e. Cruciloculina, D’Orb.

f. Spiroloculina, D’Orb.

g. Ceratospirulina, Ehrenberg. Dimorphous.
Hauerina, D’Orb.

Fabularia, Defrance.

III, PENEROPLIDA.
Peneroplis, De Montfort.

a, Spirolina, Lamarck (restricted). Dimorphous.
b. Dendritina, D’Orb.

TV. ORBICULINIDA.

Orbiculina, Lamarck.

Orbitolites, Lamarck.
a. Payonia, D’Orb.

Alveolina, D’Orb.

V. DacryLoPoriIDA.

Haploporella, Giimbel.

Dactyloporella, Giimb. (Dactylopora auctorum in parte.)
Thyrsoporella, Giimb.

Gryroporella, Giimb.

Cylindrella, Giimb.

Uteria, Michelin.

Acicularia, D’ Archiac.

Verticillipora (?), Mantell.

Receptaculites, Defrance.

Archezocyathus, Billings.

II, FORAMINIFERA ARENACEA,
I, PARKERIADA.

Parkeria, Carpenter.
Loftusia, Brady.

IJ. Lrrvonima.

Endothyra, Phillips.

Involutina, Terquem.

Trochammina, Parker and Jones. Monothalamous in some forms,
a. Webbina, D’Orb. (restricted). Fixed.

Valvulina, D’Orb. Sometimes dimorphous.

Tetrataxis, Ehrenberg.

Ataxophragmium, Reuss (sandy Bulimina),

Plecanium, Reuss (sandy Texrtularia).

89

90

Transactions of the Royal Microscopical Society.

Sacecammina, Sars. Monothalamous in one form.

a. Psammosphera, F. E. Schulze. Monothalamous ?

b. Storthosphera, F. E. Schulze. Monothalamous.
Pilulina, Carpenter.* Monothalamous.

Astrorbiza, Sandahl. Monothalamous.

a. Astrodiscus, F. E. Schulze. Monothalamous.
Rhabdammina, Carpenter. Monothalamous?
Botellina, Carpenter. Monothalamous.

Proteonina, Williamson. Monothalamous?
Lituola, Lamarck. Often dimorphous.

a. Placopsilina, D’Orb. Fixed.

b. Haplophragmium, Reuss. Often dimorphous.

c. Haplostiche, Reuss.

d. Hippocrepina, Parker.

e. Polyphragma, Reuss.

f. Conulina (?), D’Orb.

TI. FORAMINIFERA PERFORATA VEL HYALINA.

I, LAGENIDA.

Ellipsoidina, Seguenza.
Lagena, Walker and Jacob. Monothalamous.

a. Entosolenia, Ehrenberg.

b. Fissurina, Reuss.
Ramulina, Jones. Slightly segmented, branching.
Nodosarina, Parker and Jones.

a. Glandulina, D’Orb.

b. Nodosaria, Lamarck.

c. Dentalina, D’Orb.

d. Lingulina, D’Orb.

e. Lingulinopsis, Reuss. Dimorphous.

f. Rimulina, D’Orb.

g. Vaginulina, D’Orb. Dimorphous usually.

h. Marginulina, D’Orb. Dimorphous.

7. Psecadium, Reuss. Dimorphous.

j. Cristellaria, Lamk, Sometimes dimorphious.

k, Planularia, Defr

1. Flabellina, D’Orb. Dimorphous.

m. Frondicularia, Defrance.

n. Amphimorphina, Neugeb. Dimorphous.
Orthocerina, D’Orb.

a. Dentalinopsis, Reuss. Dimorphous.

II. PoLyMoRPHINIDA.T

Polymorphina, D’Orb.

a, Dimorphina, D’Orb. (restricted). Dimorphous.
Uvigerina, D’Orb.

a. Sagrina, D’Orb. (restricted), Dimorphous.:

Ill. Buiiminipa.

Bulimina, D’Orb.
a. Ataxophragmium (sandy), Reuss,
b. Bolivina, D’Orb.

* For this and some other allied forms, see Dr. Carpenter’s ‘ Descriptive

Catalogue of Objects from Deep-sea Dredgings exhibited at the Soirée of the
Royal Microscopical Society, King’s College, April 20th, 1870.’ 8vo. London,

1870.
+ The Polymorphinida ave separated from the Lagenida only on account of their

alternite arrangement of chambers,

Remarks on the Foraminifera. By Prof. T. Rupert Jones. 91

ce, Virgulina, D’Orb.
d, Bifarina, P. and J. Dimorphous.
e. Robertina, D’Orb.
Cassidulina, D’Orb. -
a. Ehrenbergina, Reuss. Dimorphous.

TV. TExTULARIDA.

Textularia, Defrance.
a, Plecanium (sandy), Reuss.
6. Bigenerina, D'Orb. Dimorphous.
e. Spiroplecta, Ehrenb. Dimorphous.
d, Gaudryina, D’Orb. Dimorphous.
e. Verneuilina, D’Orb.
f. Tritaxia, Reuss. Dimorphous.
g. Clavulina, D’Orb. (restricted). Dimorphous.
h. Heterostomella, Reuss. Dimorplious.
7. Vulvulina, D’Orb.
j. Venilina, Giimbel. Dimorphous.
k, Candeina, D’Orb.
/7. Cuneolina, D’Orb.

VY. GLOBIGERINIDA.
(1.) Globigerinina.

Ovulites, Lamarck. Monothalamous.
Orbulina, D’Orb. Monethalamous usually.
Globigerina, D’Orb.
Pullenia, Parker and Jones.
Spheeroidina, D’Orb.
Carpenteria, Gray. Fixed.
Allomorphina, Reuss.*
Chilostomella, Reuss.*

(2.) Rotalina.
Spirillina, Ehrenb. (restricted). Monothalamous,
Discorbina, Parker and Jones.
Planorbulina, D’Orb. Fixed in some cases.
a. Planulina, D’Orb.
b. Truneatulina, D’Orb, Fixed.
Pulvinulina, Parker and Jones.
Rotalia, Lamarck (restricted).
Cymbalopora, Von Hagenow.
Thalamopora, Reuss.
Calcarina, D’Orb.
Tinoporus, De Montfort (restricted).
Patellina, Williamson.
Conulites, Carter.
Polytrema, Risso. Fixed.

(3.) Polystomel/ina.
Polystomella, Lamarck (restricted),
a. Nonionina, D’Orb.

(4.) Nummulinina,

Nummulina, D’Orb.
a, Opereulina, D’Orb.
b. Assilina, D’Orb.
Amphistegina, D’Orb.
Heterostegina, D’Orb.

* The systematic place of these two forms is not well understood.
VOL. XY. H

92 Transactions of the Royal Microscopical Society.

Cycloclypeus, Carpenter.
Orbitoides, D’Orb.

Fusulina, Fischer.
Archeospherina (?), Dawson.
Archeediscus, Brady.

Eozoon, Dawson. Fixed.

( The systematic place of the following is not yet determined.)

Caunopora, Phillips.
Ccenostroma, Winchell.
Sparsispongia, D’Orb.
Stromatocerium, Hall.
Stromatopora, Goldfuss.

®
PROGRESS OF MICROSCOPICAL SCIENCE.

Vegetable Parasites in Corals.—In the ‘ Proceedings of the Royal
Society’ (No. 164), in a long and valuable paper by Mr. H. N.
Moseley on corals found during the ‘ Challenger’ expedition, there
appears the following note on the question of parasitism :—The
corallum of both Millepora and Pocillopora is permeated by fine
ramified canals, formed by parasitic vegetable organisms of the same
nature as those described by Dr. Carpenter and Professor K6lliker as
occurring in the shells of mollusks, &«. The organisms were found
in abundant fructification ; they are green, but otherwise appear to be
fungi, as are the parasites of shells, &c. Similar parasites are to be
found in various coralla from widely distant parts of the world.

Form and Size of the Batrachian Blood-corpuscles.—Professor Gul-
liver, F.R.S., in his recent paper before the Zoological Society makes
the following observations on the blood-globules of the Batrachia :—
On each broad surface they are generally flat or somewhat vaulted ;
and their outline is regularly a well-defined oval figure, mixed occa-
sionally with a few of a suboval or even circular shape, as indeed is
the case among all regularly elliptical blood-disks, though this is
rarer in Birds than in the lower classes and in the Camels. In
Batrachians, the short diameter of the corpuscle being taken as 1, its
long diameter would vary commonly between 1} and 13. The thick-
ness of the corpuscle is about one-third of its short diameter ; and the
nucleus may be either subrotund, or more commonly liker in shape to
the envelope. The largest red blood-corpuscles of Vertebrates occur
in the tailed Batrachians, of which Amphiuma, a cauducibranchiate
species, has the largest of all, so that these are visible to the naked
eye, and the perennibranchiate Proteus the next in size; and in
Steboldia, which has deciduous gills, the corpuscles are larger than in
Siredon, which has permanent gills. In Amphiwma and Proteus the
corpuscles are at least thrice as large as in some Frogs and Toads—
an amount of difference of which there 1s no example either in the
class of Birds or Reptiles, though it is exceeded among Apyrenemata,
The corpuscles in the anurous Batrachians are not always bigger
than, and sometimes not so long as, in a few Reptiles and in some
Sharks and Rays. The size of the corpuscles in Batrachians may
differ in the same individual at different seasons. A few more obser-
vations on the corpuscles in this class are given in the ‘ Procecdings
of the Zoological Society, February 4, 1873.

( 94 )

NOTES AND MEMORANDA.

Examining the Blood-globules.—Our readers will remember that
some time ago there was an important discussion in these pages
between Dr. Woodward and Dr. Richardson relative to the possi-
bility of distinguishing the blood-globules of man from those of
other mammalia with sufficient accuracy to determine points in
medical jurisprudence. Now Dr. Richardson sends us a micro-
photograph on which the blood of man and the pig are represented
beside each other, and asks us whether they are not quite distinct.
We answer, in the present instance they are perfectly distinct not
only in size but in form, but we question whether this is always the
case. However, the specimen is of interest.

An Improved Form of Cox’s Turn-table.— We learn from the
‘ American Naturalist’ for December 1875, that Miller Bros. of New
York have made an improved form of this excellent contrivance,
which is marked by its handsome iron stand and its careful adjust-
ment of the centering movements. “TIf,’ says the ‘A. N.,’ “the
real convenience of this table were known, its use would soon become
general.”

CORRESPONDENCE.

Herr Hasert’s Opsuctives: A Repry to F.R.M.S.
To the Editor of the *‘ Monthly Microscopical Journal.’

EIsEnaAcH, January 9, 1876.

Dear Sir,—Fair play, if you please. Having been rather wantonly
attacked by some man in your Journal, I hope you will give my reply
a place in your columns. The report given by Mr. Hickie is cer-
tainly a statement of facts, after careful investigation, while the abuse
of the Fellow R.M.S. seems to have no other foundation but ill-will.
How much credit Dr. Dippel deserves, the following will show to all
who interest themselves for truth. In two letters of Dr. Dippel, in
my possession, dated 1861, 4/5 and 7/7, he says, “your objectives
resolve in direct light from a north window, No. III. the XII., and
No. II. the XX. group of Nobert’s scale most distinctly ;’ in the
second letter he says, “used with the achromatic condenser, both
systems give very sharply defined images excellently suited for the
most subtle anatomical investigations.”

How much Dr. Dippel has since perfected himself in disregarding
facts, I do not know, not having seen his edition since 1872; but in
his first edition you will find sufficient contradictions regarding my
lenses, if you will compare pages 119 with 143 and 169, where he
gives my lenses in one place the highest resolving powers for diatoms,

QE

CORRESPONDENCE. 95

in the other puts them down again. His love of truth and fair deal-
ing is shown by the following observations :

Having advertised my objectives not needing correction, in the
year 1864 I had a microscope exhibited at our meeting of “ Natur-
forscher und Aérzte,” in Giessen, giving everyone an opportunity to
convince himself of the fact—the object-glass was j},th. After the
lovers of truth had convinced themselves of the correctness of my
statement, in comes Dr. Dippel, bringing along with him an object,
covered with a piece of looking-glass plate of at least three-quarters of
a millim. in thickness, through which he knew well enough no 7th in
the world could reach, requesting me to put it under the microscope,
to try how it would work with various thickness of covering glasses.
When I told him that such covers could not be used under any lens of
high power, he went away declining to make any trial of the lens, and
then he threw out his innuendves without any positive statements.
Whether my lenses are capable of doing service, Dr. Schumann
has shown. And in spite of the tyro-like brasswork, nearly all our
first-class microscopists have either such bad microscopes or object-
glasses of my construction, which are not made to look at, but to look
through. Hoping you will help to right a much-wronged man,

I am most truly yours,
B. Haserr.

[We have pleasure in inserting Herr Hasert’s letter. We have
not altered his modes of expression, through a desire to maintain the
exact character of his remarks.—Ebp. ‘ M. M. J.’]

THe New Powerit anp LEALAND 11H.
To the Editor of the * Monthly Microscopical Journal,’
Bristot ScHoon or CuEemistry, December 31, 1875.

Sir,—In communicating the following notes, I must premise that
I have no wish to advocate any particular interest, nor yet to take part
in the hot controversy which I regret to see raging round the peaceful
instrument which has often given me peace. My aim is solely to
endeavour to aid working microscopists by the results of my own
experience.

In your June issue, Mr. Slack published some remarks on the
“ New-formula” 1th of Messrs. Powell and Lealand which were very
discouraging to those hoping to employ it for general work. Whilst
fully admitting its exquisite resolving power on diatom tests, he
stated that its working distance was extremely small and its penetra-
tion very limited, while it was difficult to use inasmuch as it gave
a rapid, almost violent transition from perfect performance to bad
performance, or even no performance at all, This report was dis-
heartening, coming from such a well-known microscopist ; but how-
ever it might have applied to the particular glass examined by
Mr. Slack (which Iam given to understand was one of the earliest
dry ones), it is so singularly inapplicable to my more recent “ im-

96 CORRESPONDENCE.

mersion,” that it reads like a precise inversion of the real facts.
I will not enter at present on the superb defining and resolving
power of this glass (which remains clear and crisp under E ocular),
but confine myself to the question of penetration and facility of
working.

Having lately, through the kindness of Mr. Curties, had a selec-
tion for examination of Zeiss’ }ths and ;);ths, I took the opportunity
to make an exhaustive comparison of the relative penetration of these
low-angled glasses (only 105°) against the Powell and Lealand ith,
fully expecting to find the latter surpassed in this respect. I em-
ployed every kind of object which an 1th could focus. I first took
the coarser and more uneven diatoms: then spores, pollens, blood-
disks, and the like; followed by the finer sections of vegetal and
animal tissues, down to uncovered sections of rock containing crystals
or arborescences in different planes. In every case, even these last
extreme ones, the new 1th gave at least as fine a general or per-
spective “ picture,” while the definition was of course far sharper.
Hence I feel confident that every class of workers, histologists as
well as diatomists, may derive the full benefit of this improvement in
the objective, which seems to me the most important advance since
the days of Andrew Ross. It is true that the working distance of
this glass is small for an “immersion,” being about the same as
ordinary dry {ths of large angle.

I may add that some time ago Messrs. Powell and Lealand made
me a 4}-inch of 40° for binocular use, which I find invaluable from
its penetration and beauty of definition ; also a fine l-inch of 20°.
I name this because these glasses are not in their published list, and I
should have availed myself of them long before had I known they
were procurable.

Having referred to the Zeiss lenses, I ought in justice to add that
I find them (the ,,th more especially) well worthy the attention of
all who may not require the highest attainable perfection. The cor-
rections are well made, and the field flat, with plenty of light. The
magnifying power of the Zeiss }th and Powell and Lealand immer-
sion 1th is the same, and measured at 10 inches with camera lucida
on Ross’s B ocular is x 640; that of the Zeiss 4,th, x 875; the
adjusting collar being set half-way in the “run” in each case.

As a chemist, I would emphatically urge all who use immersion
glasses to employ distilled water with them. Mere exposure to air,
especially when aided by gentle warmth, causes ordinary waters to
deposit an insoluble film of carbonate of lime, and when evaporation
takes place during prolonged work, sulphate of lime may follow
suit, and this cannot be dissolved off even by acid. It is obvious
that any such coating on the front lens must sensibly impair its
efficiency.

I am yours obediently,
Freperick W. Grirrin, Ph.D,

CORRESPONDENCE. 97

Mr. WeENHAM’s DEMONSTRATIONS ON THE IMMERSION APERTURE

QUESTION.
To the Editor of the ‘ Monthly Microscopical Journuai.’
224, Recent’ Street, Lonpon, January 12, 1876.

Sir,—When Mr. Wenham asserts that the angular aperture of the
image-pencil is the same whether the lens be used dry or with immer-
sion, he seems to be unaware that this is equivalent to asserting
that the aperture is the same whether used on uncovered or covered
objects !

In his “simple demonstration,” the refutation of his position is
contained in the item,—That the lens must in both cases—e. g. wet or
dry—be accurately focussed on the surface of the cube of glass. Now,
the accurate focus cannot be obtained with a lens adjusted for immer-
sion unless immersion contact be made; the lens when so adjusted will
not give a sharp image of an uncovered object: so that when he
speaks of adjusting a certain +1,th for immersion and focussing on the
surface of the cube of glass before the water is introduced, he cannot
be describing an actual experiment. It is no valid measurement of
the aperture of the image-pencil unless the lens be so adjusted as to
give true definition of the glass surface in each trial. There is no
such thing, properly speaking, as aperture, unless the image of a point
is seen as, approximately at least, a point; and that can only be ascer-
tained either by trial or by going through a mass of laborious calcula-
tions.

Having satisfied myself that the position taken by Dr. Woodward
and Professor Keith on the immersion aperture question can be sub-
stantiated both theoretically and experimentally, I gladly availed
myself of Mr. Wenham’s invitation to witness a practical demonstra-
tion directed by himself. By the terms of his letter, I was at liberty
to have the test made with any lens in my possession. Accordingly,
as he had already published a report of his measurement of the
angular aperture of a ith immersion objective made by Tolles, of
Boston, and as this measurement did not agree with what I had
obtained with the same objective, I thought it would be more interest-
ing to have the trial made with it. The owner of the lens, Mr. Frank
Crisp, with great courtesy placed it im my hands for the purpose,
together with the semi-cylinder of glass that was described by Mr.
Wenham.

In the ‘M. M. J.,’ No. Ixiii., p. 112, Mr. Wenham gave a descrip-
tion of the method he employed; and on p. 116 he wrote that with
this identical lens and semi-cylinder, “the balsam aperture with
closed lenses was only 68°, . . . and this angle of 68° was the same
whether water was introduced or not between the plane surface of
front lens and semi-cylinder, taking care to focus (?) in either case” !
He mentions that “a minute stop of leaf metal was placed in the
centre [of the plane surface of the semi-cylinder] so as to cut off ex-
traneous rays.” On the next page he says that he had “rather over
than under estimated the aperture from using a stop too large; less
than ,1,th of an inch would have been more proper.”

98 CORRESPONDENCE.

From this it will be seen he used a stop of at least jth of an inch
diameter, and that with it he stated he measured the immersion aper-
ture as 68°!

I need not recapitulate the details of the method employed by
him in my presence. In every essential particular the conditions
stated in his paper were observed; the result was that the immersion
aperture measured not 68° only, but upwards of 90°!

And again, with the same slit and with another = ‘009 inch (less
than one-half of the one described by him), and with the lens set at
its best adjustment and accurately focussed in each case on the surface
of the semi-cylinder in water contact, the apertures shown by the
bi-section of the field of the ocular, in rotating the microscope hori-
zoutally, were also beyond 90°!

I leave Mr. Wenham to explain the discrepancy between the
result he published in March 1874 and the results here given. The
facts are plain enough: we used the same }th immersion, the same
semi-cylinder, a slit opening of the width he described, viz. ;jth of an
inch ; but instead of arriving at his former result of 68°, we measured
the immersion aperture as beyond 90°. And as, in his paper, he
suggested the measurement would be still more accurate with a
narrower slit opening, we tried ‘009 inch,—and again obtained
beyond 90°,

Professor Keith has shown in the Journal for December last that
the width of the slit opening cannot affect in any way the measure-
ment of the immersion aperture. It should, however, be observed
that the practical application of a very narrow slit on the plane sur-
face of the semi-cylinder involves considerable attention; but the
refinement of the method will only make the experimental proof more
nearly c»incide with theory.

In criticising the position assumed by Mr. Wenham on the im-
mersion aperture question, I am compelled to take his utterances
in the ‘M. M. J’ as representing the views he holds. He has ex-
pressed himself unreservedly against the possibility of an object-
glass refracting image-forming rays beyond what he terms the limit
of 82° from balsam—making that appear to be the natural limit, or
“full aperture.” * Professor Keith touched upon this point in his
letter to the Journal, No. Ixiii., p. 182, thus:

“ All see that the limit 82° depends upon the difference of refractive
power at a plane surface ; that is, upon two variables ; and, therefore,
necessarily changes with a change in either of them. If balsam is
substituted for air between the objective and the cover, the refracting
surface is practically removed from the cover to the posterior surface
of the front lens, from a plane to a curve, and the limit, which depends
upon the curvature, changes with that variable.”

Mr. Wenham’s reasonings have all appeared to ignore this most im-
portant view of the question, by which it is shown that the “ critical ”
angle for refraction into air imposes no natural limit when the rays
do not go into air at all till they reach the second surface of the front
lens, which, far from being parallel to the front, is deeply curved.

* See ‘M. M. J.,’ No. xxvi, p. 117; xxvii, 'p. 118; Ixiti., p. 1197 Ixxxy. ps:

CORRESPONDENCE, 99

That the limiting angle at which rays could be admitted into balsam
through a flat plate of glass imposes any natural limit to the angle up
to which an object-glass could collect image-forming rays, supposing
them to have got into the balsam, is absurd.

In the discussion on the immersion aperture question, the point
insisted on by Dr. Woodward, Professor Keith, and Mr. Tolles, is, that,
by means of the immersion principle, image-forming rays beyond the
angle 82° from a balsam-mounted object—or from any object under
equivalent conditions —can be transmitted into the optical image: the
question then refers only to rays from balsam beyond the angle of 82°.
Dr. Woodward’s demonstrations, supported by Professor Keith’s com-
putation, were brought forward in illustration of the fact that by a
properly devised objective such rays are transmissible. As Mr. Wen-
ham rejects Professor Keith’s diagram, he is bound to prove it erroneous,
by a graphical method if he likes, marking in the same data. It will
not do for him to reject the diagram on the ground that the data were
furnished by Mr. Tolles to “suit the proposition ;” for, since this dis-
cussion has been revived, M. Prazmowski, of the firm of Hartnack et
Prazmowski, the well-known opticians of Paris and Potsdam, has sub-
mitted for my inspection a number of his computations referring to
immersion lenses made any time during the last fourteen years, every
one of which contains distinct tracing, by the trigonometrical method,
of rays from the conjugate focus of greater angle than those trans-
missible by a dry objective. It is therefore evident that formule,
involving the transmission of an angle of image-forming rays greater
than corresponds to the maximum air-angle, have been known during
this number of years.

Mr. Wenham’s demonstrations seem to have been based on the
assumption that his diagram in the ‘M. M. J., No. xxv., p. 23, ex-
plained the ‘whole theory of the action of the immersion system.
But the rays there figured are merely the rays corresponding to those
transmitted by the dry combination,—which are not concerned in the
matter disputed. And in his so-called demonstration in No. xlvii.,
p- 281 et seq., the image-pencil belonging to the air-limit theory is the
only one with which he deals,—he takes for granted that the flat plate
limit of refraction from balsam or glass into air—82°—is the natural
limit beyond which no object-glass can collect image-forming rays.
Such an objective as the one to which he referred cannot be said to
have an immersion aperture in the proper acceptation of the term;
because, if its construction be such that its maximum aperture is ex-
pressed by the air-pencil of 170° and no more, when water is intro-
duced between the objective front and the cover-glass, the lens will
no longer render “the image of a point as, approximately at least, a
point,’—it admits of no adjustment by which a true immersion focus
can be obtained, consequently the immersion aperture cannot be deter-
mined. That demonstration does not really touch the “ balsam aper-
ture question.”

As Mr. Wenham still insists * that the angle 82° from balsam is
the natural limit, or full apertwre, “ beyond which no object-glass can

* OM: M. Ji,” No. lxxxy., p. 48:

100 CORRESPONDENCE,

collect image-forming rays,” the onus probandi rests on him. It will
not do to tell us he has repeatedly given simple demonstrations of
the truth of this proposition. I have shown that he has been lax in
testing his own demonstrations,—that with the very lens reported
upon, an immersion aperture upwards of 8° beyond the limit he
contends for has been measured by himself—with his own method—
in my presence. His former measurement must therefore be rejected,
and Dr. Woodward, Professor Keith, and Mr. Tolles may claim this
practical demonstration in proof of their position.

I would request those who are interested in the subject to observe
that in Mr. Wenham’s published account of his measurements of the
aperture of the 4th lens by 'Tolles—to which I have above referred —
several pages are devoted to an irrelevant and misleading report con-
cerning the aperture of the lens when used dry. It being admitted
that no image-forming aperture can be measured unless the lens be so
adjusted as to give a true image of the glass surface of the cube or
semi-cylinder, it is absolutely essential that means be taken to verify
whether or not this has been done. What then is the value of his
report on the air-aperture of this lens when it becomes known that at
no point of adjustment will it give a true image of an uncovered
object ? The lens was designed for immersion; it will not focus on
an uncovered object; when, therefore, he set the lens at “closed ’”’—or
maximum angle—by what process did he determine the focal distance
to be ‘013 inch, so as to enable him to state the air-aperture to be
necessarily less than 118°?

With such a front lens as that of Mr. Tolles, the aberration if used
on an uncovered object is so enormous that there is really no such
thing as an air-aperture; and by taking this or that point as the best
focal -distance, and this or that point as the best adjustment of the
lens, Mr. Wenham might have made the air-aperture anything within
180°. Apart from the question of aberration, he might have measured
the air-aperture to be any angle from about 110° to—say—175°.

‘It remains that I express my willingness to let the trial of the im-
mersion aperture of this }th lens be repeated at the Society’s rooms
—strictly according to the terms stated in Mr. Wenham’s report—on any
evening that may be appointed by the President of the Society.

T am, Sir, your obedient servant,
Joun Mayan, jun.

CourRTESY IN CORRESPONDENCE.
To the Editor of the ‘ Monthly Microscopical Journal.’

HarrLey Court, Reavine, January 14, 1876.
Dear Srr,—I doubt whether the objects of the Royal charter
granted to the Society (to which many esteem it an honour to belong)
can be said to be furthered by the style of letters sometimes commu-
nicated to the Journal.
As for those letters recently published by Messrs. Hogg, Brooke,
and Wenham, J hope and would fain believe that theset gentlemen

PROCEEDINGS OF SOCIETIES. 101

will regret on further reflection that they ever wrote them. The
time is passed when an honest search after scientific truth can be
satisfied with mere school-room versions of science. And as I enter-
tain no apprehension as to the establishment of the principles laid
down in my paper, I merely at present remark that any inquiry after
truth should be conducted with the courtesy befitting the members of
a Royally chartered Society.

I am yours faithfully,

G. W. Royston-Picorr.

Mr. Wrenuam’s EXpnanatTion oF THE ReFLex ILLUMINATOR.
To the Editor of the ‘ Monthly Microscopical Journal,

Sir,—In Mr. Wenham’s explanatory letter on the Reflex Illu-
minator in the current (January) number of the Journal, the following
passage occurs :

“ All light being thrown on top surface of slide, at an internal
angle beyond that of total reflexion, the field is quite dark with
objectives of the largest aperture—not the most extreme rays of which
can admit them.”

Will Mr. Wenham kindly explain the meaning of the phrase I
have placed in italics ?

Your obedient servant,

AKAKIA.

PROCEEDINGS OF SOCIETIES.

Royant Microscopican Soctery.

Kine’s CoLiece, January 5, 1876.

Charles Brooke, Esq., F.R.S., Vice-President, in the chair.

The minutes of the preceding meeting were read and confirmed.

A list of donations to the Society was read by the Secretary, and
the thanks of the meeting were voted to the donors.

The Secretary reminded the Fellows that the next ordinary meet-
ing would be their anniversary, at which Officers and Council for the
ensuing year would be elected; and the following list of gentlemen
nominated by the Council was then read :

As President—H. C. Sorby, Esq., F.R.8., &e.

As Vice-Presidents—Dr. W. B. Carpenter, Charles Brooke, F.R.S.,
Hugh Powell, and Rev. W. H. Dallinger.

As Treasurer—J. W. Stephenson, Esq.

As Secretaries—Messrs. H. J. Slack and Charles Stewart.

As Members of Council—Dr. Braithwaite, F. Crisp, J. E. Ingpen,
E. W. Jones, Dr. Henry Lawson, W. T. Loy, Dr. John Matthews,

102 PROCEEDINGS OF SOCIETIES,

Dr. Millar, J. R. Mummery, F. H. Ward, F. H. Wenham, C. F.
White.

The Chairman requested the meeting to appoint two gentlemen as
auditors of the Society’s accounts; when Mr. W. A. Bevington was
proposed by Mr. Curties, and seconded by Mr. Shadbolt; Mr. B. D.
Jackson was proposed by Mr. Guimaraens, and seconded by Mr.
McIntire.

The Chairman then submitted these nominations to the meeting,
and the two gentlemen named were duly elected.

The Secretary said that it would be remembered that some time
ago they received a present from Mr. Hanks, of California, consisting
for the most part of specimens of the mineral and other products of
that country. Since that time Mr. Loy had kindly mounted for the
Society a number of those specimens, and had done s0 in a very
beautiful manner, as might be seen by looking at the slides on the
table. Amongst the slides might be mentioned those of gold, silver,
various crystals, portions of fossil pine wood, a Podura, curious as
being found upon the snow of the Sierra Nevada, and also a very
beautiful polychroic substance, sesquioxide of chromium.

The thanks of the meeting were unanimously voted to Mr. Loy
for having mounted the specimens in the manner described.

Mr. Tylor said, should any of the Fellows of the Society feel
inclined to return the compliment, by sending out some objects to the
Microscopical Society of San Francisco (of which Mr. Hanks was
president) he should be very happy to take charge of them for the
purpose.

Mr. Charles Stewart called attention to some slides of Aulacodiscus
Kittoni, which had been presented to the Society by Mr. Curties,
having been obtained from matériel collected during the late Congo
expedition by Mr. Martin, of H.MS. ‘Spiteful.’ On looking at them
he found that many of the disk-like boxes were united in columns of
two or three in number, and he should like to know if this was a
merely accidental cohesion, like that which was seen in the case of
the red corpuscles of the blood, or like thin disks of cork floating
freely on water, or whether it was the result of division of the
diatoms in the process of forming two boxes out of one, after the
manner of Biddulphia. Mz. Stewart then drew the appearances he had
described upon the black-board, and observed that it would be
extremely interesting to know how this interlocking came about.

In the absence of any formal paper, Mr. Charles Stewart gave a
highly interesting description of the life history of the sponges,
showing their general structure, mode of growth and reproduction,
He illustrated his remarks by numerous drawings upon the black-
board, and concluded by explaining the probable method in which
the glass rope of the Hyalonema was formed, and also by reference to
the power of boring into hard substances possessed by some of the
smaller members of the sponge tribe.

The Vice-President expressed the great pleasure with which he—
and doubtless all present also—had listened to Mr. Stewart's remarks ;

—— yo

PROCEEDINGS OF SOCIETIES. 103

for his own part, he had not only been much interested, but had also
derived a gréat deal of information.

The thanks of the meeting were unanimously voted to Mr. Stewart
for his communication.

Mz. Hickie then exhibited to the meeting a series of photographs,
and read letters from Dr. L. Rabenhorst and Herr Seibert on the
subject of the strie of Frustulia Sazonica, with a view to prove its
complete distinction from Navicula crassinervis. (Mr. Hickie’s com-
munication will appear in our next number, having been “ crushed
out” with much other interesting matter.)

Dr. Lawson inquired if what Col. Woodward stated was correct,
viz. that the transverse strize had always a definite number, but that
the longitudinal ones varied with alteration of focus.

Mr. Hickie said that Dr. Woodward’s remark, though new, was not
true;* he could himself do exactly the same with another specimen
perfectly well known to all, and if Dr. Lawson would call upon him
he would show him exactly what Dr. Woodward had described.

Mr. Curties hoped that Mr. Hickie would succeed in throwing
some light upon the subject as to the species of this object, and
would be able to show them how Rhomboides, Crassinervis, and Frus-
tulia, when viewed by a proper and suitable glass, could be dis-
tinguished beyond the possibility of a mistake of any kind.

Mr. Hickie said the photographs marked C, D, and E, looked exactly
like Crassinervis, because in that the median line ran almost perfectly
to the end. In Saxonica it was not so, it was also pinched in at the
end, and the ratio of the diameter was greatly in excess in proportion
to the length.

Mr. Shadbolt said that when Mr. Stewart was speaking about
Aulacodiscus he was rather surprised to hear that he suggested the
probability of these shells coming together in this way accidentally.
Of course this might sometimes occur, but they could hardly expect it
to do it so as to form a whole column. In examining Arachnoidiscus
some years ago, he had not the shadow of a doubt that what he saw
there of a similar kind was the result of division. (Drawing made on
the black-board in further illustration.)

Mr. Stewart said he had intended to say that Aulacodiscus did
really increase by division, but in the particular slide in question the
fact of the columns being formed of different sized individuals led
him to suppose that in these cases it might be the result of accidental
agglomeration.

Mr. Mayall inquired what evidence there was that the objects
photographed in Germany as described by Mr. Hickie were really
Frustulia Saxonica. He had seen a great many similar objects, and
had obtained the same appearances with 1-inch or }-inch objectives,
whereas Dr. Woodward’s specimens were represented as seen by
ys-inch or ;-inch. After looking at the photographs now exhibited,
he thought they were of a coarse form of Rhomboides.

* There can be no doubt that diffraction lines can be produced as Dr. Wood-
ward states.—H. J.S.

104 PROCEEDINGS OF SOCIETIES.

Mr. Hickie thought that Prustulia Saxonica being found in
Saxony must be better known to Saxon people than others. There
really was no difference whatever between Rhomboides and Saxonica,
but there was a very great difference between them and Crassinervis.

The meeting then separated until February 2, when the anni-
versary will be held.

Donations to the Library and Cabinet since December 1, 1875:

From
Nature. Weekly La ae ee ei is LD Dalia.
Athenssum., Weekly.) prin) s cee We cutie, flames irene een Ditto.
Society of Arts Journal Society.

The Microscope in Gynecology. ‘By ‘A. Mead Edwards, M.D. Author,
Popular Science Review. No.58 .. .. .. .- . =. dior.
Transactions of the Linnean Society. Two parts.. .. .. Society.

Two Slides of Aulacodiscus Kitton’ .. .. .. .. «. «. Thomas Curties, Esq.

The following gentlemen were elected Fellows of the Society :—
The Rev. Thomas Wesley Freckelton ; William Brindley, Esq. ;
Charles William Hovenden, Esq.
Watter W. REEvEs,
Assist.-Secretary.

Mepicat MicroscopicaL Socrery.

Dec. 17, 1875.—H. Power, Esq., Vice-President, in the chair.

Dr. Pritchard exhibited in action the new freezing machine for
cutting microscopic sections, and which has already been described
in the ‘ Lancet’ for December 11, 1875. The principle upon which
its action depends is that a block of copper cooled by immersion in
ice and salt will retain its low temperature sufficiently long in water
to enable sections to be cut from a small piece of any soft tissue
placed upon it, and which by contact with it has become frozen and
adherent to its surface. If first immersed in gum water the specimens
solidified better.

In the discussion that followed, Mr. Ward suggested using a
metal plug in the same way as Dr. Pritchard recommended, only
dropping it into an ordinary microtome tube so as to obtain the addi-
tional advantage of a rest for the razor.

Mr. Groves thought that if the plug were hollowed so as to contain
some ice and salt, it would remain cold much longer.

Acari in Diabetic Urine-—Myr. Jabez Hogg showed a specimen of
urine from a case of incipient diabetes which contained large quan-
tities of the Acarus domesticus, as well as particles of indigo. 'wenty-
four hours after being voided he observed their presence, and up to
the present time they were still alive and breeding (for they were
seen in all stages of development) though six weeks had elapsed.
The mycelium of the diabetic fungus had appeared and the indigo
was increasing. It was possible that the animal fed on these two
substances. He had only examined this one specimen, and had kept
it in the bottle in which it had been sent to him, in the window
all the time. He had no doubt it was the ordinary sugar acarus,
and must have obtained access to the urine in the first instance
by accident.

THE

MONTHLY MICROSCOPICAL JOURNAL.

MARCH 1, 1876.

I.—THE PRESIDENT’S ADDRESS.
By H. C. Sorsy, F.RS., F.L.8., F.G.8., F.Z8., &c.
(Delivered before the Royau MicroscopicaL Society, Mebruary 2, 1876.)

In selecting a subject for my address, it appeared to me more
desirable to direct attention to some special questions more or less
intimately connected with branches of science which I have perhaps
studied more than most of those who are familiar with the general
applications of the microscope, rather than to pass in review the
many interesting communications that have been made to us during
the past year. These have been of that varying character which it
is so desirable for our Society to have. Several have treated on
new apparatus, and on the improvement or improved use of older
contrivances of different kinds, or on the methods to be employed
in the examination of the microscope, and in testing its perform-
ances. We have also had a number of excellent papers on single
objects of interest, both animal and vegetable, as well as others
treating on more general and wider biological subjects. On the
whole, I think we have good reason to congratulate ourselves on
what has been brought before us. Time would not allow me to
mention and discuss the various memoirs in detail, and also to lay
before you a special subject which appears to me well worthy of
consideration, viz. the relation between the limit of the powers
of the microscope and the ultimate molecules of organic and in-
organic matter. At all events, I think that this subject may lay
claim to sufficient novelty; since, so far as I have been able to
learn from consulting the index of the various volumes, no one
during the last fifteen years has treated on this question; and until
within the last few years none of the requisite data were known.
Even now many of them are so imperfect, that nothing more can
be done than to make the most probable assumptions. This
necessarily imparts more or less of a speculative character to some
parts of the subject, but I hope this will be pardoned on such an
occasion as the present. It appears to me that in his annual
address, the President of a society cannot do better than endea-
vour to point out the bearing of what is already known on some
great question ; and if in doing this the necessity of more accurate
knowledge is made apparent, there is more hope for the future.
The importance of particular classes of facts may not, and very
VOL. XV. I

106 Transactions of the Royal Microscopical Society.

often is not, apparent until their connection with some special
question is fully appreciated. It will, I am sure, be a source of
great satisfaction to me if what I shall say should lead to the more
accurate study of some of the data necessary to change my supposi-
tions into well-established conclusions, whether they agree with my
own or not.

Though fully impressed with the imperfect state of our present
knowledge of the ultimate constitution of organic matter, yet even
now the facts are sufficiently definite to indicate, if not indeed to
prove, the existence of as wide a world of structure beyond the
limit of the power of the microscope, as what has been revealed to
us by it is beyond the powers of the unassisted human eye. I
think we may very fairly conclude that the ultimate structure, even
of organic bodies, will for ever be invisible, and the only chance of
obtaining some knowledge respecting it is by indirect methods
of research. For my own part, I look forward with hope and
confidence to a great increase in our knowledge of this question by
the further study of the optical characters of both organic and in-
organic substances, that is to say, by using light so that it may
suffer changes easily appreciated by our organs of vision, though
the ultimate molecules of the object examined may be so small in
relation to the wave-length of light, that even light itself is far too
coarse a means for transmitting to our eyes any distinct impression
of actual form or magnitude. ‘There are also other branches of
physical science which serve to teach much in connection with this
subject, but as yet even these fail to satisfy all the requirements of
the case. The whole question is beset with the greatest difficulties,
and even when we make use of the best data hitherto obtained, we
see at once how very imperfect they are. One reason perhaps is
that the importance of the subject has not been sufficiently appre-
ciated, and comparatively little has been done to develop it even as
far as is possible. I think I may safely say that what has been
done relates exclusively to the elementary substances, or to the
most simple chemical compounds. Nothing, or next to nothing, is
known respecting the size and structure of the molecules of the
very complex substances met with in animals and plants, and when
we come to consider what may be their ultimate nature when form-
ing a part of living tissue, we are immediately brought face to face
with questions which have probably never once attracted the atten-
tion of physicists; since as a rule their studies do not lead them
into the consideration of biological problems.

I propose to discuss my subject under three heads:

1. The limit of the powers of the microscope.

2. The size of the ultimate molecules of organic and inorganic
matter.

3. Conclusions to be drawn from the general facts.

The President's Address. By H.C. Sorby, F.RS., &e. 107

1. Limit of the Powers of the Microscope.

In treating this question I have no intention to enter into the
consideration of the best form or arrangement of lenses to ensure
the least possible amount of spherical or chromatic aberration, nor
how far for the purposes of research it is desirable to make a com-
promise between those practical difficulties which cannot all be
entirely overcome at one time. I shall assume that the instru-
ment itself is theoretically perfect, and consider only the limit of
vision due to the organization of our own eyes, and still more that
due to the physical characters of light.

The visibility of a very minute object necessarily depends on a
number of different circumstances. If examined by transmitted
light it must either absorb sufficient to make the contrast between
it and the general field great enough for the eye to recognize, or it
must be of such a shape and of such a refractive power in relation
to the surrounding medium as to bend the light which passes near
the edges out of the general direction of the transmitted beam, so
as to give rise to a sufficiently dark and definite outline. In my
treatment of the question, I however assume that the character of
the object examined is in every respect such as would enable us to
see it, if it were not for difficulties of another kind.

The purely physiological part of the question has not attracted
much of my attention, since I did not believe that the ultimate
limit of distinct vision would be found to depend on the con-
stitution of the eye. It may, however, be well to give a short
account of some experiments made by Dr. Royston-Pigott with
the view to determine the physiological limit, which he has kindly
communicated to me, and permitted me to employ, in order to
show that the above-named conclusion is justified by experiment.
He found that the smallest visual angle that he could ever dis-
tinctly appreciate was a hole 1} inch in diameter at a distance of
1100 yards, which corresponds to about 6" of arc. This visual are
in a microscope magnifying 1000 linear would correspond to about
the three-millionth part of an inch. Some persons, however, affirm
that the smallest visible angle is 1’, or ten times the above, which
would correspond to so¢/o50 of an inch. If such be the case, the
eye could distinguish with a high magnifymg power a much
smaller interval than the physical properties of light will permit.

Taking into consideration merely the swelling out of a minute
point of light due to diffraction, Dr. Royston-Pigott thinks that the
limit of visibility must be from tsaoo00 tO socdooo of an inch.
This, however, is not what appears to be the most important cha-
racter of light in limiting the power of the microscope for separating
lines so near together that they may be obscured or their number
falsified by interference fringes.

r 2

108 Transactions of the Royal Microscopical Socrety.

This subject Has been treated of in a very complete and satis-
factory manner by Helmholtz,* whose authority on such a question
few of us would venture to dispute. In his essay he maintains
that the size of the smallest objects visible does not depend simply
on their size, but very much on the susceptibility of the eye for
faint differences in the intensity of light. For this reason the
ultimate defining power of the microscope cannot be so well deter-
mined by the examination of single bright points or lines on a dark
ground, or of single dark points or lines on a white ground, as by
the use of fine gratings, which have alternate bright and dark
stripes, as on Nobert’s test-plate, and on the frustules of Diatomaceze
and the scales of insects. He contends that in the case of such
objects the smallest distance that can be accurately defined de-
pends upon the interference of the light passing, as it were,
through the centres of the bright spaces, and that when this inter-
ference is of such a character that bright fringes are produced at
the same intervals as the dark lines, and are superimposed on
them, the lines can be no longer seen, and the normal limit of
perfect definition has been reached. He, however, points out that
by a favourable overlapping the dark portions of the fringes may
occasionally so coincide with the true lines as to make it possible to
see still smaller intervals, but that a certai and unequivocal per-
ception of such lines would scarcely be possible. He then proceeds
to show that this limit of true and distinct vision depends upon the
angle of divergence of the light. entering the object-glass of the
microscope, and on the wave-length of the hght, according to
the following relations :

d = the distance between the lines;
z = the angle of divergence ;
A = the length of the wave of the light;
then we have
A

oo : .
2 sin. a

This angle of divergence is equivalent to one-half of the true angle
of aperture, when illuminated by an equally large pencil of light ;
but at the same time one cannot but think that in actual practice
the results must be made somewhat more complex, owing to the
presence of light having a less angle of divergence than the extreme.
All the calculations are also made for true focal adjustment and
correction of the lenses, and if these be not actually correct the
combined effect of all the disturbing causes must necessarily give
rise to many appearances not easily explained. Of course these
remarks do not in any way apply to minute bright points.

The formula given by Helmholtz is entirely different from that

* Poggendorff’s ‘ Annalen,’ Jubelband, 1874, p. 573.

The President’s Address. By H. C. Sorby, F.RS., &c. 109

adopted by Nobert, which is based on the supposition that the rays
of light used for illumination are parallel, and entirely ignores the
question of aperture. As Dr. Woodward has shown,* the limit
given by Nobert’s formula is not at all borne out by observation,
since lines can be distinguished at a much smaller interval than
indicated by the manifestly incomplete theory. This remark will
not apply in the case of Helmholtz’s formula, which appears to be
fully substantiated by observation.

Adopting, then, the most simple applications of Helmholtz’s
formula as an illustration of the general question, I have calculated
what is the limit for the red and blue ends of the spectrum, and
for the mean rays, according to the following wave-lengths, given
for simplicity in fractions of an inch:

Bed ends ee cei ew, Lice yes Neeeh een See
Mean rays ——
Blue end S0s70

I have also calculated the limit for a few widely different angles
of divergence, giving double these in order to make the comparison
more simple with the angle of aperture as usually expressed,
assuming of course that the angle of divergence of the light from
the condenser is equally great.

60°, which gives the wave-length as the limit.
97°, which gives three-fourths of the wave-length as limit.
120°.
150°.
180°, or an angle so great that its sine is near unity, whether practicably
possible or not. ‘This gives for the limit half the wave-length of the
light.

The results are expressed in the following table, in which I
give the nearest round numbers:

| 60° Se | |) Saletne 150° 180°
PIT emt 1 1 1 1
Red end si ae 37000 55000 | 64000 71000 74000
ae hl 1 | 1 es pa =
Mean rays | 6000 69000 | 80000 59000 92000
| 1 1 \eener 1 1
Blueiend, | 3. - | wo000 T0000 104000 T16000 TZ0000
i
|

All these limits are calculated for dry lenses. For immersion
lenses of equal aperture the limits would in all cases be about
three-fourths of the various magnitudes here given. In order to
see such minute intervals, of course a high magnifying power is
necessary, but when the interval is less an increased power would
magnify the defects and the object equally.

* Monthly Microscopical Journal,’ vol. ii., 1869, p. 289.

110 Transactions of the Royal Microscopical Society.

An examination of the table will clearly show the value of a
large aperture in defining lines at very small intervals on flat objects
like Diatomacez, though in practice this advantage may be entirely
counterbalanced by other disadvantages in the case of a different
class of objects. The largest possible aperture would define lines
at half the distance apart that could be defined with an aperture of
only 60°. It follows from the law of the sine that there would be
a rapid increase in defining power on increasing the aperture when
small, but when large a similar increase would have no such corre-
sponding advantage. Mr. Jabez Hogg informs me that by a com-
parison of different object-glasses he has been led to conclude that
the defining power varies as the chord of the aperture, which of
course is in absolute agreement with this theory of Helmholtz. It
is the same, only expressed in different words. Of course the
defining power of different object-glasses depends on several other
circumstances ; but since we find that many of the facts may be
explained by the action of the interference fringes, depending on
the essential characters of light itself, no matter how perfect the
manufacture of the instrument or the capabilities of the eye, it
appears to me that they deserve far more consideration than has
been given to them. Their influence has been entirely over-
looked by many who have treated on this question. At all events,
since they are altogether independent of the mechanical construction
of the instrument, it appears to me that we cannot do better than
adopt these principles in forming some conclusion as to the size of
the smallest object that could be distinctly seen with a theoretically
perfect microscope. Looked at from this point of view alone, with
a dry lens this could not be less than go}o9 of an inch. Even
when zzh00 the fringes due to the extreme red rays would begin
to produce partial obscurity, and at 5sdo0 the brightest part of the
spectrum would make the obscurity more or less complete. If it
were possible to make use of the blue end alone, lines of trolooo
could still be seen, since their shorter waves would not produce
obscurity until the size was reduced to ysooo0 of an inch. The
size of the smallest bright point that could be seen depends on
entirely different considerations, and might be considerably less, as
far as the physical constitution of light 1s concerned.

The question now arises, Are these general conclusions borne
out by actual observation? As far as I am able to judge from
such evidence as I have been able to collect, they are very strongly
confirmed, if not actually established. Thus, according to Helmholtz,
Dippel* found that the limit of the true resolution of Nobert’s lines
was about sooo0 Of an inch, which is just within the limit for the
mean rays, with a very wide aperture. By theory this limit might
be considerably exceeded by the use of blue light; and, since the

* ‘Das Mikroscop und seine Anwendung,’ 1867,

The President's Address. By H. C. Sorby, F.R.S., &e. 111

rays at the blue end of the spectrum are those which are active in
photographing, it might be possible to obtain a good photograph of
lines not distinctly visible when mixed light is employed. This,
Helmholtz thinks, explains why Stinde was able to photograph lines
on Surirella gemma which were too000 Of an inch apart, and
therefore considerably within the possible limit. Helmholtz does not
appear to have seen the papers on Nobert’s bands by Stodder * and
by Dr. Woodward,} which contain many facts of great interest in
connection with this subject.

In reading these papers it is easy to perceive that the true reso-
lution of one of Nobert’s bands, which according to Dr. Woodward
contains lines at a distance of about +ys'so0 of an English inch, is
a matter of such extreme difficulty, even with the best object-
glasses, that, if the exact nature of the object and the number of
lines were not known, it would be almost impossible to decide how
many lines there were to an inch. ‘The lines due to interference
are often as distinct as. the true lines on the glass, and Dr. Wood-
ward believes that such spurious lines, and not the actual, were
seen and counted by Stodder ; since the number was not correct.
The black lines due to interference do occur beyond the limit of
the true, and at closely the same intervals as the real, as should be
the case according to Helmholtz’s theory. Now itis quite manifest
that the distinctness of definition depends on how these spurious
bands occur in relation to the true. If they exactly overlap, the
definition would be good, and the lines distinct; but, if they
occurred at the half intervals, the dark part of one series occurring
at the bright part of the other would more or less completely
obliterate both. It appears to me very probable that these facts
will in great measure explain the phenomena seen when the light
is thrown on the lines at a varying angle, since in one position the
lines cannot be defined, on increasing the obliquity false lines are
visible, and with still more oblique light the true may be seen, An
alteration in the angle of aperture of the condenser would also alter
the distance of the diffraction bands; and therefore, taking all these
facts into consideration, we may easily explain why, as Helmholtz
says, it is possible under such favourable conditions, with lines at
equal intervals, to distinguish them when closer together than what
is the normal limit of the distance at which they can be seen
without any special difficulty, even when not at equal intervals,
that is to say, when the intervals are greater than that of the bands
due to diffraction. yen then, however, they do occur in varying
numbers and position between the true lines, as may be seen in
photographed diffraction gratings.

* ‘Quart. Journ. of Micros. Science,’ 1868, vol. viii., p. 133.

+ Ibid., p. 225; ‘Monthly Microscopical Journal,’ 1871, vol. vi., p. 26; and
1872, vol. viil., p. 227.

112 Transactions of the Royal Microscopical Society.

Still, even the above-named Nobert’s band is quite within the
limits of what might be resolved by the use of blue light, and thus
there is no difficulty in understanding how it might be photographed
as done by Dr. Woodward.

Similar principles would of course apply in the case of the
very close and uniform markings on the frustules of Diatomacee.
Dr. Woodward’s paper and admirable photographs of Frustulia
Sazxonica, brought before our Society at our meeting last No-
vember,* fully bear out all Helmholtz’s conclusions, and show the
difficulty of distinguishing true structure from interference fringes
when the intervals between the real markings are of the same
order of magnitude as half the length of the waves of light. This
effect is of course altogether independent of the quality of the
lenses. It depends on the physical constitution of light itself, and
would only be the more perfectly seen with more perfect object-

lasses.

: There is also another fact mentioned by Dr. Woodward which
merits attention.t He says that for resolving very close lines or
linear markings it is a decided advantage to have the lenses some-
what under-corrected for colour. As he suggests, this may be
partly due to the possibility of making such lenses more correct
for spherical aberration, but at the same time it appears to me quite
possible that it may also to some extent be due to the fact that -
with such a correction it is possible so to have the lines in focus
for the blue rays as to take advantage of their shorter wave-length,
whilst the interference fringes due to the longer waves are suffi-
ciently modified by being out of focus as to obscure the vision less
than they otherwise would.

Taking then all these facts into consideration, it appears to me
extremely probable that for object-glasses not made on the immer-
sion principle the limit of perfectly satisfactory definition of lines .
not exactly the same distance apart must be somewhere about
zotoo Of an inch. With a dry lens having an aperture of 140°,
or an immersion of 100°, both illuminated by a condenser of equal
angle, only the extreme red rays would then serve to produce
a very slight indistinctness. Under very favourable circumstances
by varying the angle of divergence of the light passing from the
condenser, or by throwing it more from one side than from the
opposite, it would be possible to make the dark interference fringes
so coincide with dark structural lines that a considerably smaller
interval might be distinguished. ‘This, however, would be ex-
tremely difficult if not impossible, if the lines were at unequal
intervals, since any adjustment of the illumination that gave inter-
ference fringes at the proper interval and situation for one part of

* ‘Monthly Microscopical Journal,’ 1875, vol. xiv., p. 274.
+ ‘Quart. Journ. of Micros. Science,’ viii., p. 229.

The President's Address. By H. C. Sorby, F.R.S.,&ce. 118

the object would give them at such an interval and situation as
would obscure the structural lines in another part, and by no ~
single adjustment could the whole be seen correctly, but in all
cases true and spurious lines would be mixed up together. The
only chance of arriving at a true knowledge of the real structure
would be by a careful induction from the facts observed when the
illumination is made to vary; and even when a satisfactory con-
clusion could thus be drawn it would only be by acting on the
principle that the limits of simple and distinct visibility had been
passed, when light has to be treated as an agent scarcely fitted for
the requirements of the case.

When we come to the examination of single detached particles
the conditions are materially changed, but if the bright part of
the interference fringes fall on the dark boundary line of a trans-
parent particle or the bright part of a fringe on the centre of an
opaque particle, it could not be distinctly seen though its presence
might be recognized.

The limit of so}eo of an inch deduced on Helmholtz’s principle
from the physical characters of light agrees admirably with the
estimate formed independently by various great authorities on the
microscope. The mean of the estimate thus formed by Quekett,
Ross, De la Rue, and Carpenter, as quoted by Stodder, is in fact
exactly the same (sotoo of an inch), so that we cannot, I think, be
far from the truth, if we take that as the base on which to build
further conclusions. With an immersion object-glass of very large
aperture it might be possible to define an interval of somewhat less
than tooo of an inch, but probably the above-named determina-
tions were made with dry lenses. At all events, since the limit of
visibility as determined by the use of the best modern microscopes
agrees so completely with what appears to be the limit due to the
physical constitution of light, we must, I think, conclude that our
instruments do now enable us to. see intervals so small in relation
to the wave-length of light, that we can scarcely hope for improve-
ment as far as the mere visibility of minute objects 1s concerned,
whatever may remain to be done to improve their performances in
other respects.

2. The Size of the Ultimate Atoms of Matter.

Having then come to the conclusion that the limit of distinct
and unequivocal definition is somewhere about from soto0 to
rouse Of an inch, it appears to me very desirable to consider what
relation such a magnitude bears to the size of the ultimate atoms
of organic and inorganic matter. From the very nature of the
case the microscope altogether fails to throw any light on this
question, and the only course as yet open to us is to draw the best

114 Transactions of the Royal Microscopical Society.

conclusions we can from the various properties of gases. This
problem has been attacked by Stoney,* Thomson,} and Clerk-
Maxwell,t who, from various data, and by various methods of
reasoning, have endeavoured to determine the number of ultimate
atoms in a given volume of any permanent and perfect gas. In
order to avoid inconveniently long rows of figures, I have reduced
all their results to the number of ultimate atoms contained in a
space of yo of an inch cube, that is to say, IN pooodos000 Of
a cubic inch, at 0° C. and a pressure of one atmosphere. These
numbers are as follows:

Stoney’ .: ss 's- ).0 |) ee lca oe | SOI ORR One
Thomson bo ge ee, ee pas tou OS e20000 00000
Olerk-Maxwell 0. . Nes ees) get meer 311,000,000,000
Mean 4. ON. ow) ke) 20 2. 02S

As will be seen, there is a very great discrepancy between the
numbers given by Thomson and Clerk-Maxwell. This is in part
due to the fact that Thomson gives the greatest probable number,
whilst Clerk-Maxwell has endeavoured to express the true number
indicated by the phenomena of inter-diffusion of gases. The deter-
minations do to a great extent depend on the measurements of
length, and any differences are of course greatly increased when
the number of atoms in a given volume is calculated, since that
varies as the cube of the linear dimensions. Extracting the cube
root of each of the above numbers, we obtain the number of atoms
that would lie end to end in the space of yo'oo of an inch in length.
These are as follows:

Stoney wig Meckpy duly enh ece alee
THOMSON. go. ss) se, oes | Gee eta ORO
Clerk-Maxwell 2 "Us" "<. as) sen Om
Means) 3. CA tor. ee oe eee

The cube of this mean is about 10,317,000,000,000, and, taking
into consideration the various circumstances named above, it appears
to me a far more probable approximation to the truth than the
mean of the numbers in a cubic yj55 Of an inch as given by the
authors. As will be apparent from the wide differences, even this
mean result can be looked upon in no other light than a very
rough approximation; but still, when we bear in mind _ that
Thomson’s result is given as a limit, it must be admitted that
the numbers belong sufficiently to one general order of magnitude
to justify our looking upon the mean as a tolerably satisfactory
ground on which to form some provisional conclusions.

* ‘Philosophical Magazine,’ 1868, vol. xxxvi., p. 152.
+ ‘Nature,’ March 31, 1870, vol. i., p. 551.
{ Ibid., August 11, 1873, vol. vill., p. 298.

The President's Address. By H. C. Sorby, F.RS., &e. 115

Now, if the gas containing the above-named number of atoms
consisted of two volumes of hydrogen to one volume of oxygen,
when combined to form vapour of water there would be a condensa-
tion of volume from three to two, and on condensing into a liquid
a further contraction to 77> of the bulk of the vapour. Each mole-
cule of water would however consist of three atoms of gas, and hence
in order to determine the number of molecules of liquid water
iD yooo Of an inch cube, it is necessary to multiply the number in
a gas by $ x 770 x 4 = 385. ‘This gives for the number of
molecules of water in yo'5p inch cube about 3,972,000,000,000,000.
In this and all other cases I give round numbers, since any nearer
approximation is impossible.

Though living organisms contain much water, yet far more
complex substances enter into their composition. As an example
of one of these, we may take albumen. According to Lieberkiihn
its composition is expressed by the formula C,,H,,,N,.SO... It
therefore contains seventy-one times as many ultimate atoms as
water, and its atomic weight is about eighty-two times that of
water. In the condition of horn I find that its specific gravity is
about 1°31. Calculating from these data, I conclude that when
the various constituents combine they contract to ,°> of the -total
volume, and not as water to 3; and that the volume of a single
molecule of albumen is about 55°6 that of a molecule of liquid
water. If their form be similar, their diameter must therefore be
3°82 times that of a molecule of water. This would lead us to
conclude that in a cube of y)55 of an inch of horn there are about
71,000,000,000,000 molecules of albumen.

According then to these principles there would be in the
length of soto of an inch about 2000 molecules of water, or 520
of albumen, and hence, in order to see the ultimate constitution of
organic bodies, it would be necessary to use a magnifying power
of from 500 to 2000 times greater than those we now possess.
These, however, for the reasons already given, would be of no use
unless the waves of light were some 2y'59 part of the length they
are, and our eyes and instruments correspondingly perfect. It will
thus be seen that, even with our highest and best powers, we are
about as far from seeing the ultimate constitution of organic matter
as the naked eye is from seeing the smallest objects which they now
reveal to us. Nor does there appear to be much hope that we ever
shall see the ultimate constituents, since light itself is manifestly
of too coarse a nature, even if it were possible to still further
develop our optical resources. As matters now stand we are about
as far from a knowledge of the ultimate structure of organic bodieg
as we should be of the contents of a newspaper seen with the naked
eye at a distance of a third of a mile, under which circumstances
the letters of various sizes would correspond to the smaller and

116 Transactions of the Royal Microscopical Society.

larger ultimate molecules. This being the case, we may feel per-
suaded that particles of organic matter, hke the spores of many
living organisms scarcely visible with the highest magnifying
powers, and, if seen, quite undistinguishable from one another,
might yet differ in an almost infinite number of structural
characters, just as any number of different newspapers in various
languages or with varying contents would look alike at the distance
of a third of a mile.

3. General Conclusions to be deduced from the above Facts.

When we come to the application of these principles to the
study of living matter, we are immediately led to feel how very
little we know respecting some of the most important questions
that could occupy our attention—questions which certainly never
presented themselves to me, until 1 looked upon them from this
point of view, and which perhaps have not occurred to anyone
before. As illustrations of the subject now under consideration,
I do not think I can select better than the facts bearing on
the size anl character of minute germs, and on Darwin’s theory
of ultimate organized gemmules, as described in Part 1. chapter
xxvii. of his work on the variation of animals and plants under
domestication. So far as I have been able to learn, he has nowhere
given any opinion as to the probable size of such gemmules, nor
discussed the probability of some of his speculations when examined
from a numerical point of view, and in connection with the pro-
bable size of the ultimate molecules of organized matter. I there-
fore propose to do so; since, though not actually a microscopical
question, it is most intimately connected with our studies, and as
microscopists I think we have a good claim to investigate objects
that are just beyond our magnifying powers.

For the sake of simplicity I will take into consideration only
the albuminous constituents of animals, using the term albumen
in a sort of generic sense, to include many compounds, which differ
in many particulars, and yet have many in common. With slight
modifications the same principles would apply in the case of other
substances. Whatever be the special variety of this constituent, it
is so associated with water in living tissues that in most, if not in
all, cases they would cease to live if thoroughly dried. This is
exemplified by the case of hair and horn, which must contain much
water at the growing end, but are dead where hard and dry. In
living tissues much of the water is no doubt present simply as
a liquid mechanically mixed with the living particles, but it appears
to me that we ought to look upon some portion as being in a state
of molecular combination. So little attention has been directed to
this kind of weak affinity, that its very existence is almost or quite

The President's Address. By H. C. Sorby, F.R.S., dc. 117

ignored in many large and important chemical works, and yet pro-
bably many of the phenomena of life are manifested only by such
compounds. Very much light is thrown on this question by the
study of the spectra and other optical characters of coloured sub-
stances. These clearly prove that when dissolved in any liquid the
optical properties of the solution depend in part on the nature of
the solvent, and are by no means the same as they would be if
minute particles of the solid substance were diffused in the liquid.
These facts cannot, I think, be explained unless we conclude that
the solvent is to some extent in the state of molecular combination
with the substance dissolved. This molecular affinity is also in
some cases manifested by a swelling up of a solid substance when
placed in some liquids, even when perfect solution occurs to a very
limited extent. Such a condition appears to be very characteristic
of the living tissues of animals, and makes it sufficiently probable
that the ultimate living particles are molecular compounds with
water, and not molecules of free dry albuminous substances.

Unfortunately, nothing definite is known respecting this ques-
tion, and all that can now be done by way of illustration is to make
some sort of a probable supposition. Taking everything into con-
sideration, it appears to me that, as a reasonable example, we may
assume that living albuminous tissue contains one-half of its volume
of water mechanically mixed, and one-fourth its volume of free
albumen united molecularly with an equal volume of water. On
this supposition the number of molecules in yo'oo of an inch cube
would be about

JNO So oS ce | Adoles on sob ES 18,000,000,000,000
Water in molecular combination... .. 992,000,000,000,000
1,010,000,000,000,Q00

Since, however, the form of minute living organisms more
nearly approximates to spheres than to cubes, it will be more con-
venient to give the numbers in a sphere of yoo of an inch in
diameter. or this there would be about as follows:

Abu EM) Wawel al) Pech fice hock seas econ! 21 0.000,000/000:000
Water in molecular combination .. .. 520,000,000,000,000
530,000,000,000,000

In the present state of our knowledge it is perhaps impossible
to say whether or not the essential characters of living particles are
due to the structural arrangement of the molecules of this combined
water as well as of those of the albumen, and whether or not in
considering the possible variations in structure the total number of
molecules should be taken into account. The very small relative
amount of dry matter in some living animals does, however, make

118 Transactions of the Royal Microscopical Society.

it very probable that molecularly combined water really plays a part
in their structure; and on the whole we may, I think, base our
provisional calculations on the total number of molecules given
above.

The Theory of Invisible Germs.

The relation between the size of the smallest object that can be
seen, and that of the ultimate molecules of living matter, is mani-
festly a question of great importance in connection with the theory
of germs. If the ultimate molecules were much larger than they
appear to be, there would be serious objections to the theory; but,
as far as we can judge, they are sufficiently small to make it possible
for an almost endless variety of germs to exist, each having a dis-
tinct structural character, and yet each so small that there is no
probability of our ever being able to see them, even as indefinite
points. Thus, according to the principles described above, a sphere

of organized matter one-tenth of the diameter of the smallest particle |

that could be clearly defined with our highest powers, might con-
tain a million molecules of albumen and molecularly combined
water. Variations in number, chemical character, and arrange-
ment, would in such a case admit of an almost boundless variety
of structural characters. The final velocity with which such ex-
tremely minute particles would subside in air must be so slow that
they could penetrate into almost every place to which the atmo-
sphere has access.

Darwin’s Theory of Pangenesis.

Darwin’s theory of pangenesis is an attempt to give something
like a reasonable explanation of the phenomena of inheritance, and is
not necessarily connected with the question of the evolution of new

species. A full account of the theory will be found in his work on -

the variation of animals. At p. 374 of vol. 11. he says that “he
assumes that cells before their conversion into completely passive or
formed material, throw off minute granules or atoms, which circulate
freely throughout the system, and when supplied with proper nutri-
ment multiply by self-division, subsequently becoming developed
into cells like those from which they were derived. ‘These granules
for the sake of distinctness may be called cell-gemmules, or, as the
cellular theory is not fully established, simply gemmules. They are
supposed to be transmitted from the parents to their offspring, and
are generally developed in the generation which immediately suc-
ceeds, but are often transmitted in a dormant state during many
generations, and are then developed. ‘Their development is sup-
posed to depend on their union with other partially developed cells
or gemmules which precede them in the regular course of growth.

The Presidents Address. By H. C. Sorby, F.RS. &e. 119

Gemmules are supposed to be thrown off by every cell or unit, not
only during the adult state, but during all the stages of develop-
ment. He assumes that the gemmules in their dormant state have
a mutual affinity for each other, leading to their aggregation imto
buds or into the sexual elements. ‘These assumptions constitute
the provisional hypothesis which he calls Pangenesis.”

In order to form some opinion as to whether the ultimate
molecules of organic matter are of such a size as to make this
theory possible or probable, it is necessary to form some idea as
to the number of such molecules that may be united to make
one gemmule. It must be very considerable, or else it seems
difficult to understand how they could vary enough to explain the
inheritance of many characters. Perhaps, for the sake of argument,
we may assume that on an average each contains something like
a million. Varying numbers, chemical constitution, and arrange-
ment, would in such a case allow of an almost infinite variety ; but
of course we are so profoundly ignorant of many necessary details
that this number can be looked upon only as a rough illustration of
the application of a general method of study. On this supposition
one thousand such gemmules massed together would form a sphere
just distinctly visible with our highest and best magnifying powers.
If the gemmules were of much greater or of much less magnitude,
it appears to me very probable that Darwin’s theory would break
down from two opposite causes, or would need very considerable
modification, because, if much greater, their number would be too
few to transmit sufficiently varied characters, and, if much less,
they could scarcely contain enough of the ultimate atoms of matter
to have a sufficiently varied individual character to transmit, since
of the assumed million ultimate molecules only eighteen thousand
would be of a true protoplasmic nature, the rest being of water in
molecular combination.

Adopting, then, this size as a basis for calculation, it is easy to
form some opinion as to the number of gemmules that might be
present in spermatozoa or in ova, assuming them to be their sole
or chief constituent. Thus, for example, if we take g,'y5 of an inch
as the mean diameter of a single mammalian spermatozoon, it
might contain two and a half millions of such gemmules. If these
were lost, destroyed, or fully developed at the rate of one in each
second, this number would be exhausted in about one month ;
but, since a number of spermatozoa appears to be necessary to
produce perfect fertilization, it is quite easy to understand that the
number of gemmules introduced into the ovum may be so great
that the influence of the male parent may be very marked, even
after having been, as regards particular characters, apparently
dormant for many years.

Then, again, adopting ,,'55 of an inch as the mean diameter of

VOL. XV. K

120 Transactions of the Royal Microscopical Society.

the germinal vesicle of a mammalian ovum, it might contain above
five hundred millions of gemmules. If these were lost or fully
developed at the rate of one in each second, this number would not
be exhausted until after a period of seventeen years. There would
thus be no difficulty in understanding why the characters of the
female parent might remain during life, even though apparently
dormant for many years. ‘This is still more the case if we take
into consideration the entire ovum, since calculating on the sup-
position of its being a sphere ;4, of an inch in diameter it might
contain so many gemmules that if one were lost or developed in
each second they might not all be exhausted until after 5600
years.

These calculations are made on the supposition that the entire
mass is composed of gemmules. Of this there is little probability ;
but still, even if a considerable portion of the ovum consists of
completely formed material and of mere nutritive matter, it may yet
contain a sufficient number of gemmules to explain all the facts
contemplated by the theory of pangenesis. The presence of any
considerable amount of such passive matter in the spermatozoa
would certainly be a serious difficulty in the way of the theory,
unless indeed a very considerable number are invariably concerned
in producing fertilization.

When, however, we come to apply similar reasoning to the
inheritance by the second or following generations of characters
which have remained apparently dormant in one or more previous
generations, it appears to me that the gemmule theory would fail,
unless gemmules have the power of reproducing others more or less
closely resembling themselves, and of collecting together more
especially in the sexual elements. This will, I think, be apparent
from the following considerations.

An animal weighing 8 stones would contain about 3000 cubic
inches, and thus its entire volume would be about six millions of
millions times that of the germinal vesicle of an ovum. Hence, if
the number of gemmules in a vesicle as given above were present
in the grown-up animal and equally distributed over the whole
body, there would only be enough to allow one for each thousand
ova, or only one for a much greater number of spermatozoa.

I have treated this question entirely in its physical aspect, and
made no reference to any other class of facts. The conclusions to
which I have been thus led agree remarkably well with those of
Darwin, though drawn from entirely different data. As will be
seen, the probable size of the ultimate molecules of living matter is
sufficiently minute to make the gemmule theory possible when
examined from a purely physical point of view. If there had been
good evidence to prove that. the ultimate atoms of matter are
very much larger than indicated by the properties of gases, the

The President's Address. By H. C. Sorby, F.RS., &c. 121

gemmule theory could scarcely have been maintained, since the
possible number of gemmules that could have been present in the
germinal vesicle or spermatozoa would not have been adequate to
explain the various facts of inheritance.

Conclusion.

As I have pointed out in the course of my remarks, there is
still unfortunately very much doubt respecting many most im-
portant questions connected with this subject, and therefore my
conclusions can be looked upon only as a first attempt to apply
a physical kind of argument to various biological speculations.
Even if our present knowledge is inadequate to make this attempt
satisfactory, I trust that what I have said will be sufficient to
show the need of a more complete study of the various questions
to which I have directed attention. I hope myself to study them
much more fully as soon as circumstances will permit. Such an
inquiry at all events serves to show how very little is yet known
respecting some of the most important facts connected with the
phenomena of life, and perhaps there is no more fruitful source of
knowledge than to see and feel how little is accurately known, and
how much remains to be learned.

122 Transactions of the Royal Microscopical Society.

1l.—Further Notes on Frustulia Saxonica.
By W. J. Hicxm, M.A., St. John’s College, Cambridge.

(Read before the Royau Microscopican Society, January 5, 1876.)
PuatE CXXX.*

BrrorE I make any remarks on Dr. Woodward’s paper, I would ask
permission to read a letter which I have just received from Dr. L.
Rabenhorst, late of Dresden. His letter is as follows:

“WVitta Luisa, By Mrtssen, December 27, 1875.

“ Honoured Sir,—In reply to your favour of the 11th of this
month, I must frankly acknowledge that I still faithfully remember
that you showed me one evening in Dresden, and therefore by
lamplight, Frustulia Saconica, with its distinct and sharply out-
lined striz-system; but I must also as faithfully and frankly ac-
knowledge that I subsequently, and only lately, failed myself to
resolve the longitudinal lines with one of Gundlach’s strongest
immersion lenses.t But then I must observe that I work only by
daylight, and never by lamplight, out of regard for my eyesight.

“Tf now Dr. Woodward maintains that Frustulia Saaonica is
identical with Navicula crassinervis, we must suppose that he is
ignorant of one or other of them.

“ Yours respectfully,
“Dr. L. Rasennorst.”

It will be observed here that Dr. Rabenhorst states that what
I showed him was Frustulia Sawonica, and that I showed him
both lines ; for his expression, “Streifensystem,” includes both lines.

I will now hand over Herr Seibert’s photographs for your
inspection, when I have first read his letter which accompanied
them. .

“ OpriscuEes Instirut von Serpert & Krarrr, WETZLAR,
“ December 20, 1875.

“Honoured Sir,—I herewith send you the two photographs
you wished for, and hope they will enable you to convince Dr.
Woodward that the lines do exist. They can be seen only by the
help of direct sunlight ; better, however, when the light is modified
by some blue material. Of course, very good objectives are required
for the purpose ; but it is not the strength of the objective that
conditions the visibility. One can see them with my No. 7;
better, however, with my No. 8, one of which you possess. ‘To be
sure, the stronger objectives show the strie more easily, but with ©

1 advantage.
ac = “Yours most respectfully,

“W, SErIBert.”

* This Plate represents the two separate photographs sent by Herr Seibert, and
labelled by him “ Frustulia Sachs.” The photographs have been enlarged twice
in the Plate. Only one-half of the strie of each frustule has been reproduced.

+ This is easily accounted for. Dr. Rabenhorst told me himself, that his
slides of Frustulia Saxonica were such poor things in comparison with the ones I
showed him, that he should not care to let me see them.

00:6

De

Fa

TheMonthly Microscopical ournal Mar] 1876.

W. West & Co Lith.

4

a —

Further Notes on Frustulia Saxonica. By W.J. Hickie. 1238

I may here remark that Dr. Woodward has altogether mistaken
the purport of what I said. I questioned but little the possibility
of his failing to resolve this or that series of difficult strize with a
double-nosed ,th. I also quite as little questioned the amount of
inference he might draw from so large a number as two slides,
being mindful of the old proverb,

“ But when one’s proofs are aptly chosen,
Two are as valid as two dozen.”

What I said, or intended to say, was this, that I fairly believe I
have spent more hours in the study of Frustulia Saxonica than
Dr. Woodward has spent minutes, and that, during my residence in
Germany, I had carefully gone over more than five hundred slides
of Frustulia, and out of that number had selected two so coarsely
marked, as to be easily resolved with a medium power.* And I
say now that, if any gentleman present will give himself the trouble

of calling upon me, | will undertake to show him the longitudinal

lines on either of those two slides, and that too without any sus-
picion of “diffraction phenomena.” Within the last few days
I have purchased from Mr. Wheeler a third coarsely marked slide,
which also allows its longitudinal lines to be easily resolved.

As for Dr. Woodward’s new criterion for distinguishing the
real from the visionary lines, I would observe that, though it may
be new, it certainly is not true; for I will undertake, in the sight
of the gentleman who may visit me, to play the very same tricks
with undoubtedly real lines that Dr. Woodward has with what he
considers to be spurious lines, and will select for the purpose some
diatom well known to all of us. Herr Seibert tells us that very good
objectives are required to show the longitudinal lines. Dr. Wood-
ward, on the other hand, has made it abundantly evident that very
moderate objectives suffice to play diffraction tricks.

I shall not here raise any question as to lenses employed: the
“ personal equation” also need not detain us; for we are all aware
that all microscopists have equal skill: it is only their lenses that
differ; that is to say, every man has a better one than his
neighbour.

“°-Tis with our lenses as our watches; none
Are just alike, yet each believes his own.”

Much also still remains to be learned, even about diatoms, and
it is evident that Dr. Woodward has not learned it.
It has ever been held to be a wholesome exercise for every man

* To give an instance in point: on Moller’s Probe-Platte may be found a
specimen of what Moller, with his characteristic felicity of nomenclature, calls
“ Nitzschia curvula.’ On my Moller’s Probe-Platte this diatom, either from the
awkward way in which it is placed on the cover, or from the inherent difficulty
of that particular shell, has given me more trouble than any other on that slide.
And yet, on a slide of the very same diatom, given to me by Mr. Kitton, I can
readily resolve the frustules, one after another, with an ordinary 31-inch,

124 Transactions of the Royal Microscopical Society.

to ride his own hobby, whether that be “ diffraction phenomena,”
or any other ; only he must take care that his hobby do not throw
him. But Dr. Woodward has ridden his hobby at a pace which
will hardly be salutary for his reputation. If his theories be
correct, and if the results of assisted vision be so utterly untrust-
worthy, what becomes of the microscope as an aid in scientific
research ? or is his meaning only, that microscopists on this side of
the Atlantic must not presume to publish any opinion without
licence first obtained under his broad seal, but must in all cases
telegraph their doubts to Washington, and wait in patience for the
Washington imprimatur ?

I think also that his suggestion, that men of such eminence as
Rabenhorst, Lindig and Seibert are incapable of steering clear of
so well known an obstruction as diffraction, is—to put it mildly—
in questionable taste.

Indeed, it would seem as though Dr. Woodward cared more
on which side of the Atlantic a thing is said, than for the statement
itself.

In Mr. G. W. Morehouse’s article “On Microscopic Powers,” *
we read: “ First-class 1ths to =ths are showing the transverse
striee of Amphipleura pellucida, Navicula crassinervis, Prustulia

Saxonica, and Nitzschia curvula. The =5th reveals longitudinal -

lines on all these, much finer than the transverse, and evidently
genuine. Under favourable conditions the resolution into the so-
called beading is distinctly effected on the first three named.”
And in another article, contributed to the ‘American Naturalist,’
and reprinted in the ‘M.M.J.,’} the same gentleman says: “F’rus-
tulia Saxonica. In addition to my observation of longitudinal
lines upon this test and resolution into dots, it may be worth noting

that, even with lamp illumination, the ,4,th has displayed the —

transverse much clearer than they appear in Dr. Woodward’s photo-
print.t This is one of the most difficult test diatoms thus far
studied, ranking but little easier than A. pellucida, N. crassinervis,
and Nitzschia ewrvula.” It will be seen here that Mr. Morehouse
has anticipated me in saying all I had to say in my letter
of last July, and has said it with more particularity. He has
not only seen genuine longitudinal lines on Frustulia Saaonica,
but has resolved them into dots. He further states that the longi-
tudinal lines are “much finer than the transverse.” He also,—as
do all men who know anything about the matter,—regards Prustulia
Saxonica as not identical with Navicula crassinervis; and, that
there might be no mistake as to the tendency of his remarks, he
has expressly referred to Dr. Woodward’s paper in the ‘ Lens.’

* ‘M, M. J.,’ vol. x., p. 150.
t Vol. xii., p. 23.
t ‘Lens,’ yol.1., p. 197.

Further Notes on Frustulia Sawonica. By W. J, Hickie, 125

Of the ‘ American Naturalist’ I know nothing; and even of
the ‘Lens’ itself I have seen only the small sheet forwarded by
Dr. Woodward on the 27th of last October. Mr. Morehouse’s
papers also did not come under my notice till long after my letter
was written, as I am in the habit of obtainig the back volumes of
the ‘M. M. J’ very irregularly and at uncertain intervals. It now
rests with Dr. Woodward to explain how it happens that, while he
silently acquiesced in Mr. Morehouse’s strictures, a courteous letter
from this side of the Atlantic could draw from him two such para-
graphs as those I shall proceed to quote from his present paper.

On page 274 he says: “It will be observed that I did not, in
my ‘ Note,’ speak generally, as Mr. Hickie does, of what ‘ Dippel
and others’ fancied they saw, but specifically of the longitudinal
strize of Dippel.” . . . . “In my ‘Note, then, I spoke only of the
longitudinal striz of Dippel, but now, in response to Mr. Hickie’s
letter, I willingly express my belief that the longitudinal lines
which he describes are of the same character.”

That is to say, I ought to have spoken “specifically,” as he did,
and with all fulness of knowledge, in July, about a matter of which
I neither had, nor could have, any knowledge till the 27th of the
following October, when he himself sent me the information. Of
course, the idea suggested to his readers is that I have been tamper-
ing with the text of his article by interpolating “and others,”
from a desire to make it appear that his views are opposed to those
held by microscopists in general, while they really are at variance
only with certain rash statements put forth by an obscure German
called Dippel.

Again, on page 279 he says: “ Mr. Hickie asserts that there is
a difference, but does not make clear in what the difference con-
sists. I should be happy to learn further from him on this head,
if he has anything to teach.”

Just so, in the Prussian “ Reddymadasy,” opposite the picture of
a wine glass, we find,* “This is a wine glass. Out of this folks
drink wine—when they can get it.”

Elsewhere also he has invited me to produce fresh evidence
for his consideration. This I must decline to do, as there
would be little profit in arguing with one whose fundamental
axiom seems to be, like Hume’s, that “No amount of evidence is
sufficient to prove such and such things.”

My own letter was written in all good faith and sincerity, and was
rather an indirect expression of my high estimate of Dr. Woodward
himself, than any correction of erroneous views, about which I

* See page 78 of the ‘Hand-Fibel’; fiinfundreissigste Auflage. Preis unge-
bunden 4 Sgr. Berlin, 1872. A respectable volume, though it omits the im-
portant fact recorded by Dr. Woodward, that schwach gezeichnet is the German for
“very pale.”

126 Transactions of the Royal Microscopical Society.

really did not care two pins; and I certainly did expect a different
answer; for though it is impossible not to admire the amazing
dexterity with which his has been put together, it is equally im-
possible not to perceive that its object is rather victory than any search
after truth, and that scientific truth is an object quite secondary to
his desire to bar the way against fresh evidence by the antecedent
prejudice of “ diffraction phenomena.”

It is indeed a clever paper, but its cleverness is in its attorney-
ship ; and its only effect will be to lay him open to the reproach,
that his reputation for infallibility is dearer to him than the truth.

And now, as all here have probably examined Dr. Woodward’s
photographs by this time, if any of you will take upon you to declare
that they represent to you the veritable Frustulia Saxonica, as it
is known in Germany, I will say no more.

For my own part, the more I look at them, the more I am
puzzled to make out for what purpose they were made or sent.

Only on two of them,—those marked with the letters A and F,—
can I discern any resemblance.

As for the others,—those marked with the letters B, C, D,
and E,—they may represent anything, or nothing.

And here, @ propos to their very peculiar colour, I would remark
that, if we, purely for argument’s sake, take them as Frustulias,
we shall find ourselves in something like a dilemma; for those who
are in the habit of working on Frustulia Saxoniea know well that,
of the whole number of frustules on a slide, more than two-thirds are
usually of a rusty brown colour, while the rest are of a clear French
white; and that it is only the latter which are capable of being
resolved. The rusty ones they may as well let alone.

They will also notice that, if they happen to focus too deeply,
or to set the adjustment-screw far wrong, the result will be to
convert the previous clear French white colour of the shell they
are looking at into the dingy rusty colour which is natural to the
irresoluble ones.

So that, if, as I said before, we imagine for the nonce his to be
Frustulias, we are driven to the conclusion that, either (1) he does
not know what frustules he ought to try at, or (2) that his photo-
graphs have all been made with the objective out of focus.

I niyself adopt the first.

We need not here discuss the goodness or badness of his slides :
his fault has been that he mistook one slide for another.

One gentleman has gone at once to the roct of the matter
by asking, “ But what 7s Frustulia Sawonica?” As some help
towards solving this riddle, I have brought with me two unques-
tionable slides of that diatom, which I will ask some of you to put
under the microscope and to exhibit for me. A careful examination
will show you, on the very same slide, some specimens even longer

Further Notes on Frustulia Saxonica. By W.J. Hickie. 127

and narrower than the one represented on Herr Seibert’s photo-
graphs, which he has so thoughtfully, lest we should make a mistake,
labelled “Frustulia Sachs.,” and some, again, which are much
shorter, and, comparatively, twice as plump; so that an opinion
based on an examination of one specimen may be upset by a glance
at the next. If now we remove the slide of Frustulia, and substitute
a slide of “ small Rhomboides,” that is, such a one as that presented
to me by Mr. Kitton, the observer will be somewhat puzzled to tell
which slide he is looking at; for there also he will see some as long
and as narrow as Herr Seibert’s, though—strange to say—the short
and plump ones are in a large majority, which is not the case on
the slides of Frustulia Saxonica by Rodig and Moller, which I
produce.

On “large Khomboides,” however, and especially on that known
as “ Bennis Lake Rhomboides,’ we can, indeed, see a difference ;
for here we observe a palpable angle at the broadest part, and the
median line seems to run right on to the terminal margin, while the
central knot is much more conspicuous.

But, as regards our “small Rhomboides,” a repeated comparison
of Mr. Kitton’s slide of this species with indubitable slides of Frus-
tulia Saxonica compels me to do that which Dr. Woodward has
declined to do, namely, to retract a previous erroneous statement,
and to confess that I am unable to state where “ Prustulia
Saxonica” ends and our “ small Rhomboides” begins, and that, in
spite of casual differences here and there in colour and in their
resolution, they really are the same thing under different names;
so that, if we call our small Rhomboides Frustulia Anglica, and
its Saxon congener Frustulia Saxonica, and Dr. Woodward’s Frus-
tulia, when he finds it, Frustulia Woodwardia, we shall, I suppose,
have satisfied all parties.

I will further remind you of a few simple facts. Dr. Raben-
horst discovered a certain diatom in Saxon Switzerland and named
it Frustulia Saxonica. De Brebisson also, as I understand, dis-
covered a certain diatom and named it Navicula crassinervis, and did
so under the impression that what he so named was something totally
different from what Dr. Rabenhorst had called Frustulia Saxonica.
Dr. Rabenhorst, again, in the letter I read to you, says expressly,
that he who identifies these two diatoms, must be ignorant of one
or other of them.

Now, if there be any two greater Continental authorities on
this point than Dr, Rabenhorst and the late De Brebisson, I should
like to know who they are.

I have now said all that I intended to say, and have said it at
some length, as I do not intend to revert to this subject again,
either in reply to any future remarks of Dr. Woodward’s, or in
reply to any other person who may care to reopen the question.

( 18.)

IIlI.—On the Characters of Spherical and Chromatic Aberration
arising from Eecentrical Refraction, and their relations to
Chromatic Dispersion. By Dr. Royston-Picort, M.A., F.B.S.,
FCPS.

Tuer paper which I last had the honour of submitting to the Royal
Microscopical Society treated of the characters of spherical and
chromatic aberration, which are identical. In that paper, none of
the statements of which need correction, the peculiar spherical
aberrations of red and blue light were scrutinized and their actual
spherical (i. e. their marginal) aberrations calculated approximately.*

On referring to Professor Littrow’s paper on “ Double Object-
glasses,” the reader will see at pages 240, 241, that he says,

“The principal of these properties (in a proposed double
object-glass) is that all rays, red as well as violet, incident near to
or far from the axis shall all unite after the fourth refraction in
one point of the axis.” That is to say, that these coloured rays,
whether marginal or central, shall at last have a common focal
point.

He then proceeds to test in section (7) this union of all the
rays considered, namely, violet, red, and mean rays by his formule.

He takes the case of crown glass and flint glass with indices
1:53 and 1°58 respectively and 3 for the ratio of their dispersions.
He then calculates the points at which the violet and red rays cut
the axis by means of the formula for spherical aberration depending
on the radii of the lenses and their refractive indices.

In order to find whether the dispersion of colours has been
destroyed, he determines the points at which the red and violet
rays cut the axis.

He gives several examples of determining the points at which
the red, violet, and mean rays cut the axis after refraction through
the object-glass, of which I beg to subjoin an example in which the
aperture of object-glass is 9°62 inches and focal length 5 feet
(a most extraordinary short focal length).

For this construction he says, page 249, “I found the focal
length (proportions used)

bo

For mean rays incident at an angle of 10° 803875 Chromatic

For mean rays incident near axis (i.e. geo- aberration.

metrical focus) 2°30379 4
For violet rays 2°30879 iagoae
For red rays 2°30378 ( )

* The principal focus varies with each change in the refractive index, i.e.
with the colour, and this would introduce further small changes neglected in the
Appendix to the last paper.

t Vol. iii., ‘Mem. Roy. Astr. Soc.’

~—

Spherical and Chromatic Aberration. By Dr. Royston-Pigott. 129

Professor Littrow concludes his paper by saying,

“The preceding calculations are therefore equally simple and
exact, as they leave the beaten path of finding the spherical aberra-
tion by an approximate expression, and determine this aberration
for any angle however large with perfect accuracy ... .”

It would be of no interest to the Fellows to quote the whole
formula used by Littrow as an improvement on Sir J. F. Herschel’s
method, but I may be excused for quoting another example, as it
bears very strongly on the principal feature of these papers. He
says,

“ In order to find how far the chromatic aberration has been
destroyed, we have (if B' be focal length and n,n' indices of
refraction)

n— 1

nr

5 (01

woeni(-+5)+@'- (5+5)+

when the radii of the lenses are 7 and s and r’ and s’, and d the
thickness of the first lens: and this equation is absolutely the
expression for finding the aberration of two lenses for each kind
of coloured light tested.

The same formula is employed over and over again to test the
amount of spherical and chromatic aberration introduced by the
lenses: and hence in this respect the characters of the two are
absolutely identical.

In standard works on optics, chromatic aberration and spherical
are treated for convenience as distinct things. It may be noticed,
however, that Professor Potter has discarded the term chromatic
aberration and employs the term longitudinal dispersion, also used
by Coddington in 1831.

Thus, in Art. 84, p. 113, pt. i., 8rd edition, Professor Potter’s
proposition is thus worded :

“To find the longitudinal dispersion and least circle of chro-
matic dispersion in a given lens.”

He then finds the longitudinal dispersion for rays whose
indices are different (such as red and violet), which is simply the
chromatic aberration along the axis of the coloured rays.

Further on he says the condition of achromatism is that v,
i.e. the distance of the focal point from the last lens shall remain
the same for all colours. |

Inasmuch therefore as the longitudinal dispersion or chromatic
aberration is obtained from the spherical equations, in other words,
as the particular coloured light entering a given lens is then sub-
jected to the spherical laws of refraction in precisely the same way
as homogeneous light would be—so far their chromatic and spherical
aberration are identical in character.

The question turns entirely upon the definition of the terms

130 Spherical and Chromatic Aberration. By Dr. Royston-Pigott.

used. Potter’s term, longitudinal dispersion, is precise and self-
evident. The term chromatic aberration has been so loosely em-
ployed as to give rise to sufficient confusion.

Thus chromatic dispersion is simply applied to denote the
various ways in which the colours in a solar spectrum are dispersed
over its whole length, which vary in their degree, position, and
intensity, according to the nature of the light and prisms employed.

Again, in the standard optical works the chromatic aberration,
calculated, is merely the variation of the focal length for the central
rays forming what is called the geometrical focus, which, mathe-
matically speaking, is used only for an infinitely small axial pencil
of rays passing through the exact centre of the lens in question :
but the chromatic aberration of a given coloured ray passing through
the periphery or marginal area of the lens is altogether omitted,
although implied in the fundamental formule.

Further, the popular canon in achromatics, that achromatism is
determined by the condition that the dispersions of the two achro-
matizing lenses must simply be in proportion to their focal lengths,
is a rough formula, only true for the geometrical focal lengths: for
it is entirely founded on the fundamental value of the focal lengths
of the central rays, and even the thickness of the lenses is entirely
neglected in this popular canon, and only two colours can be
united for the dispersions of the two sets of rays chosen.

Opticians have determined for themselves the fallacy of this
canon for delicate purposes, and of the two necessary evils chosen
the least. In forming a telescope of two glasses, they find minute
double stars are shown most distinctly when the secondary spectrum
or uncorrected colour is faintly purplish, or claret colour.

On referring to Brewster’s treatise on Optics,* the identical
character of chromatic and spherical aberration is well implied.
He says, p. 79,

“In treating of the progress of rays through lenses, it was
taken for granted that the light was homogeneous, and that every
ray that had the same angle of incidence had also the same angle of
refraction, or what is the same thing, that every ray which fell
upon the lens had the same index of refraction. The observations
in the preceding chapters have proved, however, that this is not
true, and that in the case of light falling upon crown glass there
are rays with every possible index of refraction from 1°5258 to
1-5466, the index of refraction for the violet rays ”

“The extreme red rays (marginal) will have their focus in r,
whilst the extreme marginal violet rays whose index of refrac-
tion is 1°5466 will have their focus in v. The distance vr ts
called the chromatic aberration.” And I may remark, there is

* Lardner’s ‘Cab. Cyclop.,’ “ Optics,” by D. Brewster, LL.D., F.R.S., after-
wards Sir David Brewster,

Spherical and Chromatic Aberration. By Dr. Royston-Pigott. 131

no way of finding this mathematically, except by the calculation
of the aberration of the red and violet rays from the spherical
formula involving their indices of refraction and radii of surfaces,
and thickness.

The chromatic aberration is finely shown by a very large
burning-glass. The author possesses one of 8 inches in diameter.
If the whole be covered up except a half-inch rim, the image of the
sun will be seen of different colours on a semi-transparent screen
held at the various foci. Each colour produces its own brilliant
focal image in order, and their exact positions measure in some
degree the dispersion of the glass. If now the whole be covered
up except an inch in the centre, the order will be the same as
before, but their former positions are altered. The difference
between the positions of the red image of the sun, for instance, is
the spherical aberration of the red for the given glass and curvature :
and the variation of the position of the violet image of the sun for
the marginal and central rays of the burning-glass is the spherical
aberration of the violet; and is absolutely identical with the
spherical aberration of the marginal rays of that kind of light
which has the same refractive power as the red or violet in
question.

The chromatic dispersion, or, much better, the dispersion, is best
shown by the spectroscope, formed of several accurately constructed
symmetrical prisms, and can only be very correctly measured by
using plane instead of spherical surfaces (very perfectly formed
to bend the rays). Barlow succeeded in determining the chro-
matic dispersive power roughly by measuring the distance to
hundredths of an inch, by which lenses of different materials
formed rude achromatic images when separated by a measurable
interval, the image of a black cross on white paper being used.
This method I take the liberty to call rough, as it cannot be com-
pared for a moment to the delicate method of measuring wave-
lengths as employed in the best spectroscopes.

The very curious laws of dispersion revealed by this modern in-
strument, depending both on the intrinsic quality of the light and
the media through which it is transmitted, can be investigated now
under circumstances of unprecedented precision and advantage. The
detection of the velocity of motion, for instance, of Sirius as re-
ceding from or approaching the sun, is an example of the most
subtle process of analysis yet exhibited to mankind. Dispersion
(and its correlations) 1s now one of the most interesting depart-
ments of modern physics.

There can be no doubt that every case of marginal aberration
in a coloured ray, though identical in the laws of its refraction with
what is called spherical aberration, has yet further qualities depen-
dent on its source. Thus the aberrations of the blue rays pro-

132 Spherical and Chromatic Aberration. By Dr. Royston-Pigott.

duced by oil of cassia enclosed between two concave lenses, will
have a very different relation to that of the red ray, as compared
with the aberrations of sulphuric acid similarly enclosed.

Indeed, the variations of the chromatic and spherical aberra-
tions go, as it were, hand in hand. Spherically considered, their
characters are identical, but their qualities depend upon the nature
of the light and the media through which it is transmitted.*

(To be continued.)

Additional Note. January 14, 1876.

I have been led to the consideration of the subject in conse-
quence of the very imperfect notions and ideas afloat regarding this
very fundamental principle in optics. The advanced student of
science in general is becoming daily better acquainted with its
general laws. It was an unfortunate circumstance that for novices
it was found convenient to employ the figment that light im optics
might be considered homogeneous for the purpose of simplifying
optical formule; this veritable scholastic sham should have been
more carefully guarded and explained. The result upon general
readers has been lamentable. Spherical aberration, the grand dif-
ficulty of opticians, is thought to belong only to a pure homo-
geneous ray. Chromatism is represented as cured by regulating
the foci of lenses; whilst chromatic error is represented as having
nothing whatever to do with spherical aberration ; spherical and
chromatic aberration being thus made distinct and as it were inde-
pendent, is pernicious to optical science, as being utterly false. In
the standard optical works chromatic aberration is only treated of
centrically: the excentrical is altogether omitted. The ques-
tion is one of the most important possible in fundamental optics.
[I may further remark to-day, February 12, that spherical aberra-
tion has no existence for the central ray, but chromatic aberration
displaces the focus of the mean central rays. But the moment a
coloured ray passes marginally or excentrically, it that instant
obeys the laws of spherical aberration: and has its identical cha-
racters. |

Dr. Parkinson says, in his preface to ‘ Optics, that the work is
a new edition of Griffin’s ‘ Optics.’ To the latter gentleman, both
the present and former paper have been submitted, and from him I

* Suppose a violet ray to pass through the margin of a lens and also through
a small central aperture, then its variation in focus is identical with its spherical
aberration; and if also.a red ray pass similarly, the resulting variation in focus is
also the aberration due to the marginal curvature, so that these variations are

identical in character as being spherically produced and spherically calculated.
—(Note added Feb. 12.)

On Staining and Mounting Wood Sections. By M. H. Stiles. 133

have received the following letter this morning in reference to the
present paper, which I am privileged to insert here :
“ OsPRINGE VICARAGE, FAVERSHAM,
12 January, 1876.

“Dear Dr. Royston-Pigott,—In the enclosed paper, on which
you encourage me to express an opinion, I see nothing to modify
or alter. I understand your view to be this. The books treat of
chromatic aberration as if there were no spherical aberration. ‘This
is hypothesis which nature does not accept. Therefore the true
and exact way is to examine an exterior ray in its entire
straggling—

“(1) From the geometrical focus in virtue of what we call

spherical aberration.

“ (2) From its fellow constituents of the unrefracted ray of

white light in consequence of chromatic aberration.

“ Both of these demand consideration as coexistent causes of a
pencil not converging exactly to a point.

“This you seem to me to have accurately expressed in the
paper which | now return.

“ Believe me to be faithfully yours,
“W. N. Grirrin.”

I have received letters from equally distinguished mathe-
maticians, approving of my first paper on this subject, which I
have placed in the hands of our Honorary Secretary, Mr. Slack. I
am allowed to add that Mr. Griffin approves the first paper also,
as containing “‘ nothing inaccurate in its statements.”

1V.—On Staining and Mounting Wood Sections.
By M. H. Srizzs.

Tue staining of sections of vegetable tissues so greatly assists the
microscopist who engages in the study of their structure, that any
improvement in the preparation and mounting of such sections will,
I feel sure, be eagerly welcomed.

During the past few months I have made many experiments in
connection with this subject, and the results obtained are so good,
and the method so simple, expeditious, and, in some respects, new,
that I think I shall be justified in publishing a short outline of it.

The cutting of sections of woody or herbaceous stems and roots
does not usually present much difficulty ; simple maceration in cold
or tepid water, or, in the case of some dried specimens, in a mix-
ture of equal volumes of spirit of wine, glycerme, and water, will

134 On Staining and Mounting Wood Sections, By M. H. Stiles.

generally be sufficient preparation for the section machine. After
cutting, soak the sections in water containing about 10 per cent. of
spirit until the tissue is freed from air, or, if convenient, put them
for a few hours under the exhausted receiver of an air-pump.

In order to get the best results with staining liquids, the sec-
tions, if at all dark-coloured, should be bleached. A very cheap and
effective bleaching liquid may be made by mixing $ ounce of chloride °
of lime with a pint of water, shaking occasionally for an hour, and
after allowing the sediment to subside, decanting the clear solution.
Unless the tissue be very dark and dense, from six to twelve hours’
immersion in this liquid will be sufficient. It is not advisable to
use a stronger solution, and in any case the process of bleaching
must be watched and arrested when complete, or the objects may
become too tender to bear the subsequent preparation for mounting.
After pouring off the bleaching solution, wash the sections by soak-
ing them for at least twelve hours in water, changing frequently,
and finishing with distilled or filtered rain water.*

Previous to staining they should be placed in spirit for about an
hour. A small beaker is a convenient vessel for this and the sub-
sequent operations, and to avoid injuring the sections, they need not
be removed from this beaker until ready for mounting.

Of the aniline colours in general use, magenta and blue give
the most pleasing results. The magenta staining liquid is made
by dissolving 1 grain of the finest cake or crystal magenta in
2 ounces of spirit; the blue dye is prepared by dissolving } grain
of pure soluble blue in 1 drachm of distilled water, then adding
10 minims of dilute nitric acid and sufficient spirit to measure
2 ounces. It is a convenient plan to prepare stock solutions eight
times the strength given here, and dilute them when wanted.

The time required to stain different tissues varies, so that no
special period can be fixed: from twenty to forty minutes will
generally be sufficient, but the objects should -be examined every
few minutes to guard against their becoming too deeply coloured.
After pouring off the staining solution, wash the sections three or
four times with spirit, drain them for a few minutes by inverting
the beaker containing them over a piece of blotting paper, and then
soak them in oil of cajuput for an hour: at the end of this time
remove the oil, drain on blotting paper as before, then immerse the
sections in turpentine; after they have remained in this liquid for
an hour remove it and add fresh. The sections are now ready for
mounting in balsam or dammar, which operation should not be
long delayed.

* The elimination of the clilorine will be much facilitated by placing the
sections, after removal from the bleaching liquid, in a solution of hyposulphite
of soda (1 drachm to 4 ounces of water) for an hour and then washing as
directed.

On Staining and Mounting Wood Sections. By M. H. Stiles. 135

Dr. Beatty has recommended the staining of-sections of wood
in two colours. This may be accomplished by macerating for
twenty to thirty minutes in the magenta solution, washing with
spirit, then treating with the blue dye for five to ten minutes, well
washing, and afterwards soaking in oil of cajuput and lastly in
turpentine.

The two kinds of tissue—vascular and cellular—seem to have
a special selective power with regard to the colours employed; the
cellular more readily taking blue than red, and the vascular to a
great extent retaining red when subsequently treated for a short
time with blue. Thus a transverse section of wood carefully
double-stained will have the vessels, wood cells, and liber tissue
more or less red, and the pith, medullary rays, and cellular tissue
of the bark blue or violet.

Independently of stained wood sections, this process of pre-
paring objects for mounting in balsam or dammar admits of exten-
sive application. It is a difficult matter to thoroughly dry a deli-
cate tissue without injuring and in some cases almost obliterating
its structure, and it is well known that an imperfectly dried speci-
men will not make a satisfactory object when mounted in balsam
or dammar.

By the method here indicated, tissues far too delicate to bear the
ordinary preparation for mounting in these media, can be success-
fully treated, and a good result obtained.

I believe the use of oil of cajuput for this purpose is entirely
new, and, as the oil is not very generally known, the following notice
of its source and properties may be interesting. Oil of cajuput is
distilled from the leaves of Melaleuca minor, a plant growing in the
Molucca Islands. It is very limpid, of a pale bluish-green colour,
and has a strong but not unpleasant odour. It is miscible with
rectified spirit* and turpentine in all proportions. This oil is
superior to the oils of cloves and aniseed in being more limpid,
considerably cheaper, and in not staining the tissue treated with it
as does oil of cloves.

* Throughout this process of staining, &c., an efficient substitute for rectified
spirit will be found in methylated spirit that had been digested with animal

charcoal and carbonate of magnesia, + ounce of each to the pint, for two or three
hours, and then filtered.

VOL. XY.

iC ESE,

V.—On a Mode of Viewing the Seconds’ Hand of a Watch
through a Beetle’s Hye. By Dr. Wurrrett.

In one of the earlier numbers of the ‘M.M. Journal’ a writer
described some interesting results produced by experiments on a
beetle’s eye as seen under the microscope. Amongst other facts he’
mentioned that the movement of the seconds’ hand of a watch could
be made visible through each of the numerous lenses of which the
eye is compounded, but as he had only read of the experiment,
he was unable to explain the mode of procedure. In looking about
for something interesting to exhibit at the late soirée of the
Adelaide Club, I made many experiments with a view to produce
the above-named result, and after numerous failures I hit upon the
following simple but effective plan, which I venture to submit,
with the hope that it may be of some use to the readers of the
Journal.

Take a watch with a white face, take out the front glass, and
remove the hour and minute hands. Paste over the face of the
watch a piece of dead-black paper with a round window cut in it,
so as to leave nothing exposed but the small circle in which the
seconds’ hand rotates. Place the watch on the front of the mirror
of the microscope, and condense the light of a strong flame on the
small white circle that has been left exposed. Reflect this light
through the beetle’s eye, previously placed on the stage, just in the
same manner as if the ordinary mirror were being employed.
Bring the eye into focus, and then gradually draw back the objec-
tive by means of the fine adjustment until the images of the watch
hand appear. At first these will probably be dim, but by varying
the inclination of the watch and careful adjustment of the light
the observer will at length obtain a bright and distinct image
through each lens of the eye. The nearer the watch can be brought
to the stage without cutting off light from the condenser, the larger
will be the image. Any power may be used from } to 4 inch, but
I prefer a ;4;th, with a No. 2 eye-piece. Under this power the
images are sufficiently enlarged, and a good number of them are
included in the field. The eye may be mounted in balsam, but I
think I have obtained better results from one specially prepared
and mounted in glycerine.

ADELAIDE, SourH AUSTRALIA.

PROGRESS OF MICROSCOPICAL SCIENCE.

Examination of Coal for Diatoms.—We have received a note from
Count Castracane, calling attention to an accidental error in the
account we gave in the last December number of this Journal *
of his method of examining coal for diatoms. The ash should be
heated with hydrochloric acid, and chlorate of potash added from time
to time—not caustic potash, since, of course, this would: only tend to
neutralize the acid, or, if added in excess, would dissolve the diatoms
themselves.

A New Phyllopodous Crustacean is described by Mr. W. Lockington,
who read a paper recently before the San Francisco Microscopical
Society on the subject.— He said that the animal, which is nearly
allied to Artemia salina, the inhabitant of the salt-pans of Lymington,
inhabits the Great Salt Lake of Utah. The inferior autenne in the
male are two-jointed. The fasal joint, with a short rounded process
(in Artemia salina this is conical); the joint itself thick and rounded ;
the second or terminal joint broad and fan-shaped, and the whole
antenne somewhat resembling the mandible of a stag-beetle in general
appearance; the inferior antennez in the male and both pairs in the
female slender and filiform ; thorax with eleven pairs of branchie eyes
on short peduncles; abdomen nine-jointed; the end joint two-lobed,
each lobe bearing a variable number of sete (4-6); colour a dark
purplish brown. From the locality in which it was collected, it is
proposed to name the species Artemia Utahensis.

The Development of Lepas fascicularis and the “ Archizoéa” of Cir-
ripedia.—Dr. R. von Willemées-Suhm sent to the Royal Society a
valuable paper on the above subject, which will doubtless be fully pub-
lished in the ‘ Vhilosophical Transactions.’ The following abstract is
given of it in the last number of the ‘Proceedings of the Royal
Society, No. 165.

I. Development of the egy and of the youngest Nauplius.

The conclusions to which an investigation into the development
of the ovum, and into the changes which occur in it after its formation
up to the time when the Nauplius comes out, has led are the fol-
lowing :—1. The youngest eggs, seen in the ceca of the ovarian tubes,
are transparent cells with nucleus and nucleolus. 2. The germinal
vesicle, as well as the ovum, grows by taking up elements of yelk.
3. All the ova found in the ovary of a barnacle are in the same stage
of development. When mature ova are to be seen in the tube, small
undeveloped ova may be seen here and there in the ceca, which act
very likely as mother-cells for further breeding purposes. 4. The
spermatozoa, when fully developed, are simple hair-like filaments.
5. The mature ovum, as contained in the breeding lamelle, shows no
trace of the vesicula germinalis nor of its nucleolus. Some highly

* Wol. xiv.) pe 291; t ‘Cincinn. Med. Journal,’ January.
L 2

138 PROGRESS OF MICROSCOPICAL SCIENCE.

refractive granules may be scen here and there among the yelk-
globules. The ovum is oval in form. 6. The segmentation is very
irregular, but seems to be complete. 7. As soon as the segmentation
begins, large transparent cells are seen separating themselves from the
yelk-globules, and increasing in number as the segmentation goes on.
8. These cells form a blastoderm round the yelk. No primitive
streak could be seen; but its presence is not denied, as the object is
not favourable for these observations. 9. The blastoderm loses its
cellular structure and gives way to a granular skin. On both sides
of a longitudinal groove three pairs of appendages begin to be visible.
10. The test of the ovum extends as the embryo develops. The latter
- is very likely still enveloped by a thin blastodermic cuticle, which is
clearly visible at the ends of tail and antennz, when it comes out.
11. The development of the Nauplius in the ovum of this Lepas shows
very much the same stages as those described by Buchholz in Balanus
improvisus,
II. The Nauplius stages.

1. The Nauplius of Lepas fascicularis has, when leaving the egg, a
length of 0:35 millim. It moults at least five times, and has before
throwing off for the last time the Nauplial appendages a length of
12 millims. 2. The first stage of the Nauplius has been seen by
Darwin, who describes it, and also by Burmeister. 38. After -the first
two moults the Nauplius gets a large dorsal spine and enters a series
of stages, one of which has been described in another Lepas by Dohrn
as Archizoéa gigas. 4. Reasons are given why Archizoéa gigas is
nearly certain to be the Nauplius of Lepas australis, a species closely
allied to Lepas fuscicularis, and representing it south of the equator.
Archizoéa gigas was caught, together with the large Cyprides of Lepas
australis, during the ‘ Challenger’s’ Antarctic cruise. 5. The tail and
the caudal spine of the newly hatched Nauplius are pushed in like the
tubes of a telescope, and covered by a thin cuticle, which may be the
blastodermic one. The same envelops also the lateral horns, but has
not been seen at the end of the appendages. The carapax is as yet
quite smooth, with the lateral horns hanging down. 6. After the
first moult the tail and its spines, which have been pushed out, have a
considerable length, and the lateral horns are erected. . Only a single
pair of small spines is to be seen on the carapax. The glands inside
are unicellular. 7. The Nawplius after the second moult has, besides
the dorsal spine, a series of processes all round the edges of the
carapax, to which the unicellular glands send their ducts. Besides
the cesophagus, two glands, which formerly were indicated by an
agglomeration of cells, become visible. These glands are very likely
those which, in the Cypris stage, terminate in the sucker of the
antennee, and are known under the name of cement-glands. Mouth
and anus are present. One pair of movable spines on the tail. First
“ Archizoéa stage.” 8. Length of Nauplius in the fourth stage
6 millims. Three or four movable spines on the tail, with the six of
the next stage shining through the chitinous coverings. The glands
of the carapax are in connection with nerves, and present a large net-
work. No nerve-terminations on the lateral horns nor on the feelers.

PROGRESS OF MICROSCOPICAL SCIENCE. 139

All the processes of the carapax, as well as the lateral horns, have
openings at the top for letting out the secretions of the glands.
9. Length of Nauplius in the fifth and last stage 12 millims. Six
movable spines on the tail. Large masses of fat are assembling in
the carapax, and the Cypris-shell is forming underneath it. The first
pair of appendages develops inside the antenne of the Cypris, the
sucker being formed in the fourth joint, the second of the future
antenna. Large compound eyes become visible on both sides of the
central eye. 10. The carapax of the Nauplius has now a diameter of
2 millims. The appendages are very much like those of Archizoéa
gigas, in which Dohrn, however, has taken the third pair of appendages
for the second, and the second for the third. 11. A specimen of the
supposed larva of Lepas australis (Dohrn’s Archizoéa gigas) is figured
in the stage just before the metamorphosis into the Cypris stage takes
place; the two large compound eyes have already developed.

III. The Cypris or pupa stage.

1. The Cypris of the Atlantic, C. fascicularis, has been already de-
scribed by Claus, who has established the homology of its parts with
the Copepods. 2. Darwin has described the very large Cypris of Lepas
australis (length 3 millims.), which is in every way similar to that of
the present species—a further proof of the probability of the sugges-
tion that Dohrn’s large Nauplii are the larve of that species. 3. Our
Cypris has a length of 1:3 millim. 4. A description is given of the

‘antenne with the suckers and their glands, the development of which
from the glands in the labrum has been mentioned already. The
parts of the mouth (small labrum and three pairs of maxille and
maxillipeds) and the natatory feet, as well as the caudal appendages
with the anus at their base, are figured and described. The organs of
sense, the digestive organs, and the shell-gland, which is now very
conspicuous, offer scarcely anything that has not been seen already
by Darwin and Claus in the Cyprides of the different species of Lepas.

IV. The metamorphosis of the Cypris into the young Lepas.

1. The pupx are chiefly caught at the very surface of the sea,
where they swarm round the dead Velelle, on which they settle. They
rarely take to a colony of old barnacles. 2. Soon after settling the
new cirri are formed underneath the natatory feet, the head grows out,
the eyes are absorbed, and under the Cypris-shell the primordial
valves of the young Lepas appear, which persist during its whole life.
The Cypris-shell, with the old natatory feet, is then thrown off.
3. The young Lepas begins to form the complete shell, and fastens
itself more and more by the copious secretions of its glands, which
run through the outdrawn and enlarged head into the fixing antenne.
4, The cirri of the young Lepas develop a larger number of joints,
the shell begins to lose its transparency, the body inside turns over a
little, as has been described by Darwin, and the young Lepas is com-
plete.

The Minute Structure of Lucernaria octoradiata has been very
fully made out and published befere the French Academy (No-

140 PROGRESS OF MICROSCOPICAL SCIENCE.

vember 8, 1875) by M. Korotneff, an abstract of whose essay appears
in the ‘ Academy’ (January 1876). He finds the body of these crea-
tures composed of four layers: (1) an ectoderm covered by a cuticle ;
(2) a gelatinous layer; (3) an elastic membrane ; (4) the endoderm.
At the base of both endoderm and ectoderm are cells which transform
themselves into nematocysts, or gland-cells. The gelatinous layer
and the membrana propria are traversed by elastic fibrils which are
prolongations of endodermic cells. Two sorts of muscles are found,
longitudinal and circular, the latter always forming an external layer.
The longitudinal muscles are represented by four trunks, which com-
mence at the bottom of the foot. In the middle of the body each
trunk divides itself into two branches, and each branch enters a
bundle of tentacles. A layer of muscular fibres is also found in the
walls of the peristome, and buccal tube. The circular muscles are
found round the mouth, along the margin of the body, and in the
tentacles. ach fibre is a simple cell, containing a highly refrin-
gent fibril. A single fibril sometimes traverses a series of connected
cells.

Schultze regarded the bristles of the urticating organs (cnidocils)
as instruments of touch. M. Korotneff finds the tops of the tentacles
covered with the urticating nematocysts, each one placed in a cell
which carries its bristle (soie). The cellule is extended into a long
fibril, which traverses a bipolar or a multipolar cell, and terminates
in a little peduncle that penetrates the membrana propria. These
multipolar cells the author regards as nerve-cells, and states that the
analogy between the tactile organs of lucernaria and those of the
arthropoda is complete.

The digestive cavity contains a stomach, and four large radiating
canals, and its walls are coated with a layer of endodermie cells,
ciliated on the peristome, and single on the external walls of the
body. Among these endodermie cells are unicellular glands secreting
a digestive liquid. The surface of the cavity is enlarged by mesen-
teric filaments, one side of each filament being composed of gland-
cells, the other ciliated. The author supposes the gland-cells produce
a circulation in the cavity, and that the simple endodermic cells
absorb the nutritive fluid. He states that the sexual elements are
developed in special capsules of endodermic origin. Each capsule is
composed of the endoderm, and of an elastic membrane (membrana
propria), and is filled with ovigerous cells. A young egg has a large
germinating vesicle, which disappears in proportion as it grows. The
developed egg is surrounded by a strong membrane, and has a large
micropyle. The ripe capsule is furnished, near its base, with a canal
which serves for the exit of the sexual products. The elasticity of
the membrana propria keeps this canal shut except when the internal
pressure of the mature eggs forces it open, after which it again
closes.

The Embryogeny of the Flea——In a recent number of the ‘Academy’
there is a capital abstract of a paper lately read before the French
Academy by M. Balbiani. It states that M. Balbiani finds the ovum
of Pulex felis better adapted to researches than that of other species,

So eee

‘

PROGRESS OF MICROSCOPIOAL SCIENCE. 145

such as canis and irritans. It is more transparent, and permits the
various stages of development to be better observed. As the flea’s egg
has been described by former observers, and especially by Leuckart,
M. Balbiani merely observes concerning its envelopes, that they con-
sist in a chorion and vitelline membrane, both very thin, transparent,
and colourless. The chorion is homogeneous, without sculpture, or
superficial reticulations. The rugose shell-like aspect its surface
presents does not arise from this membrane, as Leuckart thought, but
is caused by a coating the egg receives at the moment of its expul-
sion. The micropyle openings of the chorion are numerous, and are
found at the anterior as well as at the posterior pole. In these two
regions they are grouped in circular spaces, larger in the former,
where the micropyle holes number forty-five to fifty, while in the
latter there are only twenty-five to thirty. In the anterior group only
has M. Balbiani seen spermatic filaments engaged. One or two days
after laying, the formation of the embryon begins by a thickening of
a portion of the blastodern, in the form of a band, at first broad and
diffuse, but which gradually concentres on the ventral line of the egg.
The embryonary bandelet continues to grow at its posterior part,
whence it makes a fold which penetrates the vitellus, and bends round
to the dorsal, or opposite, side of the egg. This replicated, or caudal,
extremity of the embryo thus has for its origin a veritable invagina-
tion of the blastoderm at the posterior pole, while throughout the rest
of its length the embryo results from a local transformation of the
blastodermic vesicle, and consequently remains external to the vitellus.
This mode of formation of the embryo of the Pulicids presents a type
intermediate between that of the Dipters, in which the whole embryo
is exterior, and that of the Hemipters, in which it is chiefly, and some-
times entirely, formed at the expense of a portion of the blastoderm
invaginated in the vitellus. After remarking that the egg of the flea
is too small to make sections to exhibit the embryonic layers, and the
part they play in the process of development, M. Balbiani observes,
there is no difficulty in following the development of the two mem-
branes which have received the names of the amnios and serous
envelope. With their formation, the first period of development
terminates, and at this early stage of evolution, the organ of repro-
duction is already visible in the form of a small cluster of clear
cells on the internal surface of the abdomen, immediately below
the posterior margin of the vitellus. No envelope surrounds this
mass of germinal cells, and the author formerly mentioned a similarly
precocious appearance of reproductive elements in Aphidians and
Lepidopters. The commencement of the second development period
is marked by the appearance of the rudiments of cephalic appendages
—antenne and mouth-organs—which last, by progress of evolutior,
come to be organized as in maxillary or abrading insects (broyeurs).
We know that the larva of the flea feeds on solid matters, while the
perfect insect has a mouth adapted to suction. Another peculiarity
is the appearance of the rudiments of thoracic members, though the
larva is born in an apodal state. “This tendency to produce append-
ages like the legs of other insects, and which are destined to abort in

142 PROGRESS OF MICROSCOPICAL SCIENCE.

the embryo itself, is a very interesting fact for the partisans of the
doctrine of evolution, while it is inexplicable to those who believe in
the invariability of species.” Among the phenomena of the third and
last evolution period, M. Balbiani mentions “the rupture of the serous
or external envelope of the cephalic region of the embryo, its concen-
tration on the dorsal surface as a crumpled mass, and, finally, its
penetration in the vitelline sac, or mid intestine, by an opening in the
back of the embryo. At the close of this period, a little horny plate
is found on the head of the larva, which enables it to split the mem-
brane at the time of hatching. M. Kiinckel has described and figured
this in P. felis, but M. Balbiani claims priority.

The Circulation of the Blood in the Frogq’s Lung.—The following
mode of observing this phenomenon is thus described by Herr F.
Holmgren :*—The frog (Rana esculenta is the preferable species)
is poisoned by several small doses of curare, so as to be paralyzed
for two or three days. A broad fold of the skin is taken up near
the armpit, and a curved needle, armed with a silk thread, is carried
through the basis of this fold, whereupon the thread is tied. In the
same manner a ligature is applied to the skin near the hind
legs. Between both ligatures a sufficient portion of the skin and
the thin muscular layer is removed, when the inflated lung will
protrude through the wound, and soon collapse. The frog securely
fastened upon a board in the well-known manner, the lung is put into
a chamber which fits over the hole in the table of the microscope and
is closed at both ends by glass, to allow the light to pass from the
reflector through the chamber into the tube of the microscope. If now
the lung is inflated again through a rubber tube, a most beautiful view
of the circulation can be witnessed.

Microscopic Examination of the Intestines in cases of Cholera.—A
valuable report which deals with the above subject has been recently
presented to the public by the U.S. Government. In this Dr. Danforth,
who has had to do with the microscopical portion of the inquiry, says
that “under a power of about eighty diameters, the following appear-
ances are noted: the mucous and muscular layers seemed to have been
much disturbed in their relations, and separated widely apart ; between
them a very beautiful, loosely-woven web of areolar or connective tissue
is seen sending its delicate filaments across the intervening space,
with here and there a little vessel, making its way toward the mucous
layer; the latter is unusually thin and unusually smooth on its free
surface; not a single perfect villus can be seen, but a few ‘stumps’
of villi are easily made out, as though the missing portion had been
rudely torn away. Under a power of 260, the surface of the mucous
layer is seen to be almost, in fact quite denuded of epithelium, since
not a single normal club-shaped cell can be seen. The mucous
membrane seems to have passed through some scene of violence, during
which its villi have been wrenched from their attachments, and its
clothing of epithelium stripped from its surface and carried away. It
seems almost beyond belief that.a few short hours could have so totally

* ¢Centralbl. fiir Chir.,’ No. 39,

PROGRESS OF MICROSCOPICAL SCIENCE. 143

changed the intestinal surface, but every section which I have examined
from the specimen of intestine now under consideration, presents pre-
cisely the same appearances. Peyer’s glands do not seem to be much
altered, quite to my surprise. Possibly they are slightly swollen, but
not otherwise perceptibly altered. But, after all, this is not so sur-
prising; the storm is too brief to affect tissues beneath the surface to
any great extent. It is rather like a terrible tornado desolating
everything within its reach, but limited in its ravages to objects pre-
senting salient points of attack. The submucous connective tissue
and the muscular layer are both beautifully displayed, but neither
present any evidence of disease, unless the unusual separation of the
mucous and muscular layers be regarded as such.”

Unicellular Alge Parasitic within Fossil Corals.—A capital paper on
this subject was recently presented to the Geological Society of London,
by Professor Martin Duncan, F.R.S., of which the following abstract
has been given. After noticing the works of Quekett, Rose, Wed], and
Kolliker, which refer to the existence of minute parasitic borings in
recent corals, recent shells, and a few fossil mollusca, the author de-
scribes the appearance presented by a great system of branching canals
of about 0°003 millim.in diameter, ina Thamnastrean from the Lower
Cainozoic of Tasmania. He then proceeds to examine the correspond-
ing tubes in Goniophyllum pyramidale from the Upper Silurian forma-
tion. In sections of that coral one set of tubes runs far into the hard
structure ; these are straight, cylindrical, and contain the remains of
vegetable matter. Neither these tubes, nor any others of the same
parasite, have a proper wall: they are simply excavations, the filiform.
alga replacing the organic and calcareous matter abstracted. In some
places the dark carbonaceous matter is absent, and the lumen of the
tube is distinguishable by the ready passage of transmitted light.
Other tubes run parallel to the wall, and enter by openings not larger
than their common calibre. But there are others which have a
larger diameter, and in which the cytioplasm appears to have collected
in masses resembling conidia ; and where fossilization has destroyed
much of the continuity of a tube a series of dark and more or less
spherical bodies may be seen. In some places, especially in the spaces
between the minute curved dissepiments and tabule, hosts of globular
spores, with or without tubes emanating from them, may be seen.
In Calceola sandalina corresponding structures exist sometimes, and
the method of entry of the parasite can be examined. The author
gave two instances, one of which was seen in section. A decided
flask-shaped cavity existed in the wall of the shell, opening outwards
aud rounded and closed inwards. It was crowded with globular spores
(oospores), and these, where near the sides, had penetrated the hard
shell, and thus gave a rugged and hairy appearance to the outline
of the flask-shaped cavity. After noticing minute structures in a
brachiopod included in a Silurian coral, and in a Lower Silurian
foraminifer, the author asserted, from the results of his late researches
upon the alge parasitic in corals out of his own aquarium, that the
fossil and recent forms are analogous in shape, size, and distribution.
He considers that the old parasite resembles Saprolegnia ferox in its

144 PROGRESS OF MICROSCOPICAL SCIENCE.

habit; and as he considers that Empusina, Saprolegnia, and Achlya—
members of the Protista—are the same organisms, living under
different physical conditions, he names the old form Palwachlya
penetrans ; and he believes that it entered the wall by the spores
fixing on to the organic matter, and growing by its assimilation, and
that carbonic anhydride was evolved. He considers that this acid,
assisted by the force of growth and the movement of the cytioplasm,
are sufficient to account for the presence of the tubes. Finally, the
author draws attention to the probable similarity of external conditions
in the Silurian and present times, and to the wonderful persistence of
form of this low member of the Protista.

Dr. Woodward on the Spurious Lines of Diatoms.—The ‘ American
Naturalist,’ in its January number (which is the first of a new series,
and is really an admirable number), states, that at the Philosophical
Society of Washington recently Dr. Woodward, of the Army Medical
Museum, gave an account, illustrated by photographs and illuminated
photographic pictures thrown upon a screen, of spurious lines, noticed
by Dippel, and more lately in a British periodical, as genuine, seen on
certain diatoms. The species Frustulia Saxonica has transverse lines
of extreme fineness, and longitudinal lines had been described by Dippel
and others, some asserting that the latter were coarser, and others that
they were finer than the transverse ones. Dr. Woodward showed very
clearly by his illuminated slides, enlarged on the screen 45,000
diameters, that the longitudinal lines appeared not only on the diatom,
but also on the space external to it, and similar lines appeared about
specks of dirt on the plate. These could be varied in coarseness b
different illuminations of the object. Hence he concluded that they
were spurious, and caused by diffraction of light from the midriff, or
the edge of the diatom, or any other object in the field. He remarked
that the existence of real lines could be determined by the fact
that they did not vary in number under varying illuminations or
focussing ; they were either seen uniformly or not seen at all.

Relations between Plants and Animals.——This subject has been
recently lectured on by Prof. Huxley at the Royal Institution. A
full report of the Professor’s remarks will be found in ‘ Macmillan’s
Magazine’ for February. After describing very fully some remark-
able monads which were found in an infusion made by Prof. Tyndall,
and referring in most complimentary terms to the papers published in
this Journal by Mr. Dallinger and Dr. Drysdale, the Professor con-
cluded by observing that keen and patient research induces the belief
that such an insensible series of gradations leads to the monad that it
is impossible to say at any stage of the progress—Here the line
between the animal and the plant must be drawn. It is therefore a
fair and probable speculation, though only a speculation, that as there
are some plants which can manufacture protein out of such apparently
intractable matters as carbonic acid, water, nitrate of ammonia, and
metallic salts, while others need to be supplied with their carbon and
nitrogen in the somewhat less raw form of tartrate of ammonia
and allied compounds, so there may be yet others, as is possibly the

PROGRESS OF MICROSCOPICAL SCIENCE. 145

case with the true parasitic plants, which can only manage to put
together materials still better prepared, still more nearly approximating
to protein, until such organisms are arrived at which are as much
animal as vegetable in structure, but are animal in their dependence
on other organisms for their food. The singular circumstance observed
by Meyer, that the torula of yeast, though an indubitable plant, still
flourishes most vigorously when supplied with the complex nitro-
genous substance, pepsin; the probability that the potato disease is
nourished directly by the protoplasm of the potato plant; and the
wonderful facts which have recently been brought to light respecting
insectivorous plants, all favour this view ; and tend to the conclusion
that the difference between animal and plant is one of degree rather .
than of kind, and that the problem, whether in a given case an
organism is an animal or a plant, may be essentially insoluble.

Prickle-cells in the Wall of the Stomach of certain Animals.—In
1864 M. Schultze discovered the so-called “ prickle-cells” in the
mucous membrane of the mouth and conjunctiva, and in the rete
Malpighi. A few years later these peculiar cells were found by
F. E. Schultze, in the epithelial covering of the lip, of the tongue of
the sturgeon, in the skin of Triton niger, Rana esculenta, &e. Now,
according to the ‘ Medical Record, Joh. Briimmer* has found these
cells in the first or muscle-stomach, and in the cesophagus of the
dolphin, in the stomach of the ox, in the left part of the stomach of
the horse, in the stomach of the common rat, house-mouse, water-rat,
and field-mouse. The author is of opinion that these cells occur
wherever the epithelium of the stomach is hard and like horn, and
their formation is proportional to the extent of the corneous process.
They seem by their firm attachment to form a firm tough epithelium
which serves in one place for protection—e. g. in the skin ; in another
for breaking up the food—e. g. in the wall of the stomach.

The Seeds of Collomia coccinea—A writer, who signs himself
P.J.C., writes as follows to ‘ Hardwicke’s Science Gossip’ (February
1876) :—“I have received from a friend a few of these very interest-
ing seeds; he gave me these directions to obtain a most curious
sight: ‘Having obtained your seeds, take a sharp pocket-knife, and
cut off as small a quantity as possible of the outer skin, then place it
upon your fluid slide, and cover it with a small square glass slip; at
first use your l-inch object-glass, and it looks like a small piece of
dirt, but directly you put the smallest quantity of water in at the top
of the slip, so as to touch the seed, myriads of spiracles will start
away from it, and continue so to do for nearly ten minutes. I have
tried this experiment a great many times, and always with success.’ ”

The Production of the Prothallus from the Spore of the Chara.—
Herr A. De Bary has published a recent paper on this subject in the
‘Botanische Zeitung, in which he gives a detailed account of the
manner in which the prothallus is produced from the spore in
the Chare. That the new Chara-plant does not spring directly from

* ‘Centralblatt,’ No. 28, 1875.

146 PROGRESS OF MICROSCOPICAL SCIENCE.

the spore was first shown by Pringsheim, who noticed that the plant
is a lateral outgrowth from an intermediary filamentous structure,
the vorkeim (prothallus).. De Bary finds that a lenticular portion of
the spore projects beyond the mass of the spore, from which it is soon
separated by a wall. The lenticular portion is then divided into por-
tions, one of which develops into the prothallus proper, while the
other becomes what is known as the primary root in Chara, although
it does not correspond to the structure of the same name in phane-
rogams. In passing, reference is made to parthenogenesis in Chara
crinita, which fact is confirmed by De Bary, who finds that female
plants isolated in closed glass vessels fruit abundantly.

Egg and Bud Development of Salpa spinosa.—It appears from the
January number of the ‘American Naturalist’ that Mr. W. K. Brooks
recently read a paper before the Boston Natural History Society on
the egg and bud development of Salpa spinosa (Otto). The life
history of Salpa may be stated in outline as follows: the solitary
Salpa is the female, which produces a chain of males by budding,
discharging an egg into each before birth. These eggs are impreg-
nated while the zodids of the chain are small and sexually immature,
and develop into females, which give rise to other males by budding.
After the embryo has been discharged from the body of the male, the
latter grows up, becomes sexually mature, and discharges its seminal
fluid into the water, by means of which it is carried to the eggs
within the bodies of younger chains.

The Primordial Utricle-——Herr Professor Pfeffer has lately studied
the so-called primordial utricle, with the following results, which are
given in the ‘ Botanische Zeitung,’ October 1, from ‘ Kélnische Zeitung,’
1875, 248. Protoplasm placed in contact with aqueous solutions
becomes clothed on all sides with a delicate membrane caused by
precipitation. This is the so-called primordial utricle. In proto-
plasm, certain albuminoids are dissolved, which separate out in water
because their solvent is withdrawn. But this is limited to the surface
of contact, because the membrane formed by precipitation does not
allow the solvent to pass through. What this solvent is, has not been
ascertained positively, but it is believed to be something besides the
inorganic salts which, in egg-albumen, hold a protein substance in
solution.

The Tyndall and Bastian Controversy—To attempt to give an
abstract of this is well-nigh as feasible as draining Niagara with a
teaspoon. But we shall make the effort; at the same time we may
state that our readers will find all the information that has been
published since Dr. Tyndall’s lecture was delivered, in the ‘ British
Medical Journal,’ Jan. 29, Feb. 5 and 12; ‘ Nature,’ Feb. 10 and 17;
the ‘ Lancet, Feb. 5 and 12. Dr. Tyndall's lecture contained many
points of interest, but one passage from it will give the substance of
his conclusions. After describing at some length the form of box
which he had selected for his experiment, he says :—“ On Sept. 10 the
first case of this kind was closed. The passage of a concentrated
beam across it through its two side windows then showed the air

PROGRESS OF MICROSCOPICAL SCIENCE. 147

within it to be laden with floating matter. On the 13th it was again
examined, Before the beam entered, and after it quitted the case, its
track was vivid in the air, but within the case it vanished. Three
days of quiet sufficed to cause all the floating matter to be deposited
on the sides and bottom, where it was retained by a coating of
glycerine, with which the interior surface of the case had been pur-
posely varnished. The test-tubes were then filled through the pipette,
boiled for five minutes in a bath of brine or oil, and abandoned to the
action of the moteless air. During ebullition aqueous vapour rose
from the liquid into the chamber, where it was for the most part
condensed, the uncondensed portion escaping, at a low temperature,
through the bent tubes at the top. Before the brine was removed
little stoppers of cotton-wool were inserted in the bent tubes, lest the
entrance of the air into the cooling chamber should at first be forcible
enough to carry motes along with it. As soon, however, as the
ambient temperature was assumed by the air within the case, the
cotton-wool stoppers were removed. We have here the oxygen,
nitrogen, carbonic acid, ammonia, aqueous vapour, and all the other
gaseous matters which mingle more or less with the air of a great
city. We have them, moreover, ‘ untortured’ by calcination and
unchanged even by filtration or manipulation of any kind. The
question now before us is, Can air thus retaining all its gaseous mix-
tures, but self-cleansed from mechanically suspended matter, produce
putrefaction ? To this question both the animal and vegetable
worlds return a decided negative. Among vegetables experiments
have been made with hay, turnips, tea, coffee, hops, repeated in
various ways with both acid and alkaline infusions. Among animal
substances are to be mentioned many experiments with urine ; while
beef, mutton, hare, rabbit, kidney, liver, fowl, pheasant, grouse, had-
dock, sole, salmon, cod, turbot, mullet, herring, whiting, eel, oyster,
have been all subjected to experiment.. The result is that infusions
of these substances exposed to the common air of the Royal Insti-
tution laboratory, maintained at a temperature of from 60° to 70°
Fahr., all fell into putrefaction in the course of from two to four
days. No matter where the infusions were placed, they were infallibly
smitten. The number of the tubes containing the infusions was
multiplied till it reached six hundred, but not one of them escaped
infection. In no single instance, on the other hand, did the air,
which had been proved moteless by the searching beam, show itself
to possess the least power of producing Bacterial life or the associated
phenomena of putrefaction. The power of developing such life in
atmospheric air, and the power of scattering light, are thus proved to
be indissolubly united.”

Now to this lecture Dr. Bastian published a very intemperate
reply, couched in language entirely unbefitting a follower of truth
alone.* In this he cites at length the names of a series of authors
who agree with him, among whom we find those of Schwann and-
Pasteur. He alleges that Professor Tyndall used infusions which
were not strong enough, and that he did not boil them long

* ¢ Brit. Med. Journal,’ Feb. 5.

148 PROGRESS OF MICROSCOPICAL SCIENCE.

enough (!!). He also cites an experiment performed by Dr. Burdon
Sanderson, which, according to Dr. Bastian, is proof of the develop-
ment of bacteria, not from pre-existing germs, but by spontaneous
generation. However, Professor Sanderson recognizes the fact that
they may have been developed from bacteria germs which main-
tained a power of resisting the influence of the boiling.

Now, in answer to these arguments of Dr. Bastian, Dr. Tyndall
firstly shows that the very first of Dr. Bastian’s asserted supporters—
Schwann—is a direct opponent, and that it was because Dr. Bastian
neglected to read the whole of his remarks that he came to his false
conclusions. Schwann’s statement, as Dr. Tyndall shows, is directly
opposed to Dr. Bastian ; for in Poggendorff’s ‘ Annalen’* he writes:
“At the last meeting of naturalists in Jena, I communicated experi-
ments on spontaneous generation, by which it was proved that, when
a closed glass globe containing a small quantity of an infusion of
muscle, and filled with air, is exposed to the temperature of boiling
water, so that both the liquid and the air are heated to 80° Réaumur,
then, even after a period of several months, no infusoria are generated,
and no putrefaction occurs.”

In regard to the second point, the adhesion of M. Pasteur to Dr.
Bastian’s arguments, we may give the following quotation from a
letter by M. Pasteur, published in ‘ Nature’ (Feb. 17), which shows
clearly enough, if it was not stated so in the beginning of the letter,
that he is a decided opponent of spontaneous generation :—“ Le docteur
Bastian me permettra de placer dans sa bouche ces paroles: ‘C’est
bien vrai, les expériences de M. Pasteur et celles de M. Tyndall m’ont
acculé, moi Docteur Bastian, partisan de Ja génération spontanée, dans
cette déclaration. Oui, je préfére recourir sans motif sérieux, 4 la —
croyance 4 une force résidant dans la partie amorphe des poussiéres ~
en suspension dans lair, plutdt que de la placer cette force dans la
partie organisée formée de corpuscules identiques d’aspect 4 ceux des
germes des organismes des infusions.’ Parler ainsi n’est-ce pas ayouer
sa défaite ?”

The most temperate letter which has been written on this subject
is that which appeared in ‘ Nature’ (Feb. 10), signed “Inquirer.” In
this the writer points to the difference between the results obtained
by Dr. Tyndall and Dr. B. Sanderson (differences which are more
apparent than real as regards the conclusion to which both lead), and
asks Professor Tyndall to explain the apparent contradiction. To this
letter Professor Tyndall replies by pointing out that he will leave
the repetition of such experiments to Dr. Sanderson himself, “ with
the full confidence that the ability and candour for which he is so
distinguished will lead him to a right result.” At the same time he
most fairly invites “ Inquirer” to see his infusions, and observes that
“it will give me great pleasure to show them to him.”

There is one other point in reference to this controversy, it is that
Professor Wanklyn states} that Professor Tyndall “has forgotten that
the resistance of the atmosphere retards the gravitation of infini-
tesimally small particles, and that particles too small for the highest

* Vol. xli., 1837. + ‘Brit. Med, Journal,’ Feb. 12.

PROGRESS OF MICROSCOPICAL SCIENCE. 149

microscopic power would not sink to the bottom of his boxes in three
days, and perhaps not even in three years. Furthermore the boxes
are not at all air-tight, as everyone who has studied Pettenkofer’s
classical researches will know, and Dr. Tyndall’s boxes are simply
wooden filters.” But as he further admits that the boxes will at least
act as powerfully as cotton-wool in excluding particles, there is of
course nothing more to be said.

Our conclusion cannot be drawn yet, as both sides are preparing
further experiments. But we think that Professor Tyndall has
thrown much light on the subject, and unquestionably he has come
out of the controversy with all the weight of scientific evidence and
philosophic gravity of discussion on his side, while Dr. Bastian has
done injury to his cause by adopting the well- known pbk of
defeat, “abuse of the plaintiff’s attorney.”

The Evolution of Hemoglobin.—Mr. Sorby, F.R.S., in a letter to
‘Nature’ (Feb. 17) states that the principal results of his recently
published paper* are contrary to what ‘ Nature’ stated, that hematin
is first met with in the bile of many pulmoniferous molluscs in an
abnormal state, quite unfit to serve the purposes of respiration, but
easily changed into the normal, which could, and probably does in
some cases, perform that function. Then in the blood of Planorbis we
have a solution of a herfioglobin, in which the hematin is combined
with an albuminous constituent coagulating at the low temperature of
45° C., and finally we come to the normal hemoglobin existing as red
corpuscles, containing an entirely different albuminous constituent,
coagulated at about 65°C. In all these changes in the condition of
the same fundamental radical, the oxygen carrier becomes of more and
more unstable character, and more fitted for the purposes of respira-
tion, as we advance from lower to higher types, as though advantage
had been taken of every improvement due to modified chemical or
physical constitution.

Action of certain Colouring Matters on the Tissues.—It seems that
this subject. has been recently investigated by Herr L. Gerlach, of
Erlangen, an abstract of whose paper is given by the ‘ Medical
Record’ (Jan. 15). It states that Herr Gerlach adopted the method
of saturating the tissues with this substance for days and even weeks
together ; the former experimenters, Heidenhain, Kupfer, Von Wittich,
and Thoma, only injected such a quantity of indigo carmine as re-
mained in the body for a comparatively short time. The author
injected indigo carmine into the lymph-sac of several frogs, and killed
them at intervals of two days, always renewing the injections. The
microscopic examination showed that the white blood-corpuscles are
capable of taking up indigo carmine.

1. The first traces of this action appear on the third day after the
introduction of the colouring matter. After this time, both the
number of cells which contain the pigment and the quantity of pig-
ment in the individual cells increase.

2. The cells of the connective tissue, e.g. of the tendons, take

* «Quarterly Journal of Microscopical Science.’

150 NOTES AND MEMORANDA.

up the colouring matter. This is to be observed from the fourth
day. é
"3. No indigo pigment is deposited in the bone-cells.

4, The pigment is found in the cartilaginous tissue, e.g. the
articular cartilage of the hip-joint, from the fifth day onwards. None
is found in the ground-substance or matrix.

5. The nerve-cells never contain the indigo; only in a few cases
was it found in the sympathetic ganglion-cells between the cell-
contents and the sheath.

6. The blue coloration of the epithelial cement pointed out by
Thoma and Kiittner is also true for that of the so-called endothelium,

NOTES AND MEMORANDA.

Mounting Ostracoda in a Permanent Manner.—Mr. E. Gardner
gives the following mode, in the January number of the ‘ Journal of
the Quekett Club.’ He says:—“I have been trying for a long time
to mount the Ostracoda and allied genera in a permanent manner, and
having at last fancied that I have succeeded, as my slides show no
alteration after some months, I beg to communicate my method, in the
hope that other young microscopists will improve upon it, and give
the results of their experience. I found that fluid media were of no
use, as endosmose, sooner or later, destroyed the objects, which do not
admit of being dried for mounting in resinous media. I therefore
tried a mixture of two-thirds gum arabic and one-third syrup, made
with loaf-sugar with a few drops of alcohol and creosote, and a little
corrosive sublimate. I found that a drop of this mixture hardened
sufficiently in about two days to imbed and preserve the object, and
to admit of the cell being filled up with gum dammar in benzole. I
use that prepared by White, of Litcham, in collapsible tubes. Should
the object show above, or project through the first coat of gum when
hardened, more must be dropped in, until it is quite imbedded. The
object is then covered with thin glass. My reason for mixing the
syrup with the gum arabic is merely to prevent the gum from cracking
or contracting too much when dry.”

Officers of the American Microscopical Society.—We are re-
quested to state that at-the annual meeting of the American Micro-
scopical Society of the City of New York, held Tuesday evening,
January 25, 1876, the following officers were elected for the ensuing
year :--President, John B, Rich, M.D.; Vice-President, Wm. H.
Atkinson, M.D.; Secretary, C. F. Cox; Treasurer, T. d’Orémieulx ;
Curator, O. G. Mason.

An American Adjustable Concentric Stage for the Microscope.
—We have received a letter from Mr. W. H. Bullock, a microscope-
maker of Chicago, U.S.A., in which he asserts that “the exhibition of
Mr. Crouch of the microscope with adjustable concentric stage, at the

CORRESPONDENCE. 151

December meeting of the Royal Microscopical Society, is considerably
behind the times. I exhibited a stand with the same attachment
before the Illinois Microscopical Society in December, 1870. It had
three milled screws, so that it was not necessary to use a screw-driver.
Dr. H. A. Johnson, of this city, has a stand that is central with jth
objective, and there is not a so-called concentric rotating stand of
English make that I have seen in this country that is central with 2.”
Mr. Bullock has sent us an illustrated description, which certainly
bears out some of his ideas.

A Concentrated Mode of Mounting.—The ‘ American Naturalist’
states that Mr. C. H. Robinson, of Cleveland, contributes to the
* Postal Micro-cabinet Club” a slide illustrating a method of
mounting where the space under a single large cover-glass is occupied
by a considerable number of small circles with an object in each. He
makes the circles of white zine varnish, and sometimes adds a circle
to the edge of the cover-glass as a finish. This method of mounting,
the appearance of which is decidedly handsome, is particularly appli-
cable to displaying several varieties of one species (as of selected
diatoms or of Foraminifera) on one slide, or to presenting in contrast
different methods of preparing the same species.

CORRESPONDENCE.

On tHE ImmeRsED APERTURE QUESTION.
To the Editor of the ‘ Monthly Microscopical Journal.’

Smr,—I can by no means acquiesce in the statement made by
Mr. Mayall in the last Journal. I will make a brief remark only on
the first paragraph.

The adjustment seems to be a stumbling-block for those advo-
cating an extra immersion theory. We have now in use thousands
of serviceable immersion object-glasses capable of defining most tests,
and which have no adjustment, as they are set for an average thick-
ness of cover. They answer well, because in the immersion system
the errors of cover-aberrations are nearly eliminated, and with a
balsam intermedium they would be inappreciable. The apertures of
these lenses are, I presume, taken by the usual sector method. Place
a slide with object in focus mounted dry with fluid intermedium, and
measure the aperture through the glass slip. Take another with an
object in balsam and again measure the aperture the same way. The
measurements will be similar. The balsam has given no increase. It
was known when most of us were children that a close position of
the lenses gave increase of aperture, but I cannot allow that this is
attributable to any immersion principle. I have before given this
answer. :

VOL. XV. M

152 CORRESPONDENCE.

Mr. Mayall in describing the “demonstration” overlooks, and makes
no mention of certain facts that were shown, of vital importance to the
truth of my statements regarding the Tolles’ 4th. When Mr. Mayall
unexpectedly brought this objective, I could not at the time call to
mind all the particulars of trials made two years ago, and needed re-
ference to my notes. However, I told him that the slit in the semi-
cylinder was formed by placing two strips of tinfoil across the centre,
with their edges approximating, having been set in position under a
low power by the aid of Canada balsam. I presented Mr. Mayall with
a semi-cylinder better polished and finished ; he brought the original
one, having put a slit in place, and asked about the width. I said
that it was far too wide, and so it proved, as it gave about the same
immersion apertures stated by Mr. Tolles. I then made a slit nar-
rower and with a water contact and proper adjustment ; the result was
an immersion aperture—tless than the 68° I had formerly given.
Mr. Mayall then protested that the thickness of the foil perhaps cut
off oblique rays. Thinking that there might be some reason in this
(though I did not ascertain if it was so by light coming through at
over 100°), the remedy at once occurred to me. I covered the plane
of the semi-cylinder with opaque black varnish, through which with
a steel point I made a fine clean cut exactly midway across the semi-
cylinder. The test now repeated with water again gave an angle of
less than 68°! Mr. Mayall then strongly contested that the slit was
“too narrow.” I replied that it would bear to be made wider and still
bring the angle within 82°. I wished to do this, but it was not tried,
nor can I tell the actual width of the slit as the varnish was imme-
diately wiped off, and thus the “ demonstration” ended, Mr. Mayall
only allowing such a width of slit as would support his statements,
and bring the aperture up to near what Mr. Tolles had asserted, and
I adopting a slit that would cut off lateral pencils and show the aper-
ture I had formerly stated! As we could not agree upon this point,
I concluded that it was useless to call Mr. Mayall’s notice to any
other measurements to prove my position.

From recent experiments I maintain that the narrower the slit,
the more accurate the results; I mean, of course, a slit with thin
edges, that will not cut off rays within the aperture to be tested.
It is obvious that the slit may be opened so wide as to be practically
without effect. I leave it to even the most inexperienced to judge
which direction is most conducive to accuracy, for the object of the
slit is to obtain a mere line, or film of light in the focus of the
object-glass.

The ith object-glass being out of my possession, I was unable
to make any further verifications free from impediment. I there-
fore requested Mr, Crisp to again favour me with the loan of it,
and with his usual courtesy and impartiality he has done so. I now
repeat the measurements with a semi-cylinder having in its centre a
clear line cut through black varnish, and a thin glass cover cemented
over the slit with Canada balsam. On looking through the slit it
admitted rays through beyond an angle of 130, the object-glass was
focussed to slit and carcfully adjusted for best definition, and though

CORRESPONDENCE. 153

now exactly under the conditions of an object mounted in balsam, and
thus somewhat differing from my trial of two years ago, yet the aper-
ture came out the same, viz. 68°.

Next the polished surface of front lens was again measured by
micrometer ; it was found, as before, ‘043 inch. The distance of the
immersion focus on an object in Canada balsam was now carefully
ascertained ; the object-glass being properly adjusted for aberration,
it was found to be ‘025 inch; taking the front lens for a base line,
with this height the angle is 813°, showing that an immersion angle
of 98° is simply impossible. But the utilized portion of the front lens,
through which all the rays or aperture emerge or enter, is much
within the diameter; the spot can be ascertained with the greatest
precision. With the lenses closed so as to give the largest area, the
working diameter through which the rays passed was found to be
only °033 inch.

Mr. Mayall says that he is “compelled to take my utterances
in the ‘M.M.J.’ as representing the views I hold.’ I believe he
has no alternative. I am conscious of some omissions and obscurities
in description, but had I described everything that I have tried,
this already excessively tedious controversy would have become quite
intolerable. At page 117 of this Journal for March, 1874, in ex-
plaining the use of the semi-cylinder, I say, “ And the focal front
(meaning point) of object-glass a, Fig. 4, brought to the centre of the
semi-cylinder c, at which there is a thin metal slit or stop of suitable
diameter.” Then follows this sentence: “ In this measurement I have
rather over than under estimated the aperture from using a stop too
large ; less than th of an inch would have been more proper.” There
is certainly a mistake here, carelessly written. This misplaced sen-
tence might have been left out, as the main strength of Mr. Mayall’s
argument is based upon it. I told him positively, and now repeat,
that in the conical front cap with the ;1, inch front opening I never
used either water or balsam, and that all the immersions were tried
with a slit, as I had a lively recollection of the trouble of adjusting
slits of different widths tacked on with Canada balsam, and set parallel
in place under a low power.

The conical aperture of 4, inch was adopted merely as one means
of showing that in the 1th the preposterous aperture of 180° did not
exist. I had not then discovered the slit. The idea of this, and its
adoption, was suggested by the conical aperture.

Tam very glad that Mr. Mayall, after the publication of such a
statement, suggests a trial before competent judges. I accept the
challenge with much pleasure, and hope he will form an unprejudiced
committee who will not, at all events, wade back through all the
length of this miserable controversy to seek only for dubious sentences
or anomalies of description. The simple facts before them would be,
Does this glass give an immersion angle beyond 82°, or does it not?
on the items of the immersed aperture taken with the slit and the
semi-cylinder, and also on the measurement of the diameter of the
front lens, and the length of the corrected immersion focus, on an
object in Canada balsam. The last alone will suffice to show that the

M 2

154 CORRESPONDENCE.

immersion aperture claimed by Mr. Tolles is utterly impossible in
this case. ;

Many regret the reappearance of this miserable controversy con-
cerning Mr. Tolles’ 1th, occupying as it has done over two years in
time; but, like an ill-healed sore, it breaks out again. My experi-
ments and discoveries relating to the microscope have been made for
the love of the science, they have been fully explained and freely
given at my own cost without a thought of pecuniary interest. Can
some of my opponents declare the same? Confessedly haying a
purpose, they never tire of bringing the name prominently forward.
I cannot blame the motive, although it is a quaint method of adver-
tising.* But let me express my belief that Col. Woodward and
Professor Keith are far above this, and I do not doubt for a moment
that they have discussed the question with strict integrity in accord-
ance with the purport of their ideas concerning the optics of the
microscope, and if I have not shown that deference for their opinions
that some would fain exact,} it is not for want of respect; but having
carried on experimental and practical inquiries on these subjects more
or less for twenty-five years, I consider that the experience that I
have gained entitles me to an opinion and some authority in these
questions.

And what does all this wearisome controversy, with its bickerings
and misquotations, tend to? Merely a desire to show that I deny that
a greater angle than 82° can be obtained with the immersion lens on
a balsam-mounted object. I do not make any such contradiction ;
my assertion is, that not only Mr. Tolles’ object-glasses, but all others
that I have yet scen, do not give near an angle of 82° in balsam.

I myself claim to be the first that suggested and made a practical
combination or doublet front that would give undiminished angles
thus mounted. The principle was described by me in the ‘ Quarterly
Journal of Microscopical Science, No. .xii, July, 1855. Had this
been suggested by anyone else, it would have been eagerly quoted
against me in controversy, to show that angles beyond 82° could be
got in balsam. This was a special adaptation for that very purpose ;
I have referred to it several times in evidence of my position, and
called Mr. Mayall’s attention to it particularly, but it is simply
ignored. I here reproduce the diagram. The lens (nearly a hemi-
sphere) is connected by Canada balsam to the covering glass of a
balsam-mounted object situated in the centre ata. “It will be seen

* “His (Mr. Wenham’s) recent papers have drawn the attention of micro-
scopists throughout Europe and America to the work of a brother optician, more
effectually than anything else could have done, and have exhibited more con-
clusively the difficulties overcome, and illustrated more strongly the skill mani-
fested in so overcoming them, than anything the other would have ventured to
say for himself.”—Charles Stodder, ‘M. M.J.,’ Feb. 1, 1874.

“ And now feel under great obligations to him for originating the discussion
or controversy, which has done so much to bring into notice, both in America
and Europe, the merits of American workmanship.”—Ibid., Dec. 1, 1875.

+ “While the other (Mr. Tolles), not content with having the splendid testi-
mony of Dr. Woodward and Professor Keith in his favour, must needs venture te
speak in his own behalf, with almost disastrous effect to his own lucidity.”—
J. Mayall, ‘M.M.J.,’ Aug. 1875, page 93.

CORRESPONDENCE. 155

from the position of the object, that each ray of light passing from
that point through the surface of the hemisphere will be transmitted in
straight lines in a radial direction without undergoing any refraction ;
the consequence of this is that the full and undiminished aperture of
the object-glass is made to bear upon the object.”

In this there is no need of abstruse calculations, or diagrams from
high mathematical authorities ; for such if they do not correspond with
actual results only tend to confusion, for by this diagram it can be
seen at a glance that any aperture existing in the back combination is
directly transmitted to the object in balsam without loss from refrac-
tion. If the radius of the immersion front is lengthened or falls
beyond the object, then the angle of the back combination being re-
fracted by a flatter surface, will become diminished.

As it may be argued that this only suggests a principle and is not
a practicable object-glass, inasmuch as the front lens even though
set in place was not attached to the cell as part of the system, I have
therefore just finished a cell-adapter with a front lens of this descrip-
tion, applied to a combined immersion and dry ith of fine quality, and
the result confirms the high opinion that I formed of it when the idea
first occurred to me.* When used as an ordinary water immersion
object-glass, I have yet seen nothing that equals it on tests in balsam.
It also acts perfectly as an immersion on objects mounted dry ; and,

* “When an object is seen under these circumstances, it at once shows the
great increase of distinctness that is to be obtained in the structure of the more
difficult diatomaceous tests when they are thus viewed in Canada balsam, with
the full aperture of the object-glass: markings which in the neighbouring dry
objects of the same character are scarcely discernible, are sharply and distinctly
visible under the hemisphere with the same illumination.’— Quarterly Journal
of Microscopical Science,’ July 1855, No. xii., p. 304.

156 CORRESPONDENCE.

further, it is still quite achromatic, and performs as a dry or non-
immersion objective in a highly satisfactory manner—of course, with
suitable adjustment in each case.*

I am, Sir, yours obediently,
F. H. Wenpam.

ARE THE GLANDULAR BODIES DESCRIBED BY Prorrssorn BENNETT
REALLY BENEATH THE CUTICLE ?

To the Editor of the ‘ Monthly Microscopical Journal.

OATLANDS VILLA, HarroGate, January 12, 1876.

Dear Sm,—I am ignorant of your regulations respecting the
papers published in the ‘M. M. J.,’ but, if it be allowed, I should
like to make a few remarks on a portion of Mr. Bennett's paper in
the January number, with a view to their publication in the next.

It is there stated that on the leaves of Callitriche verna there are
a number of glandular bodies, similar in many respects to those found
on the leaves of Drosera and Pinguicula, They are said to be “nearly
spherical, and distinctly quadripartite, each division being again filled
with a yellowish-brown substance,” and to be “entirely concealed
beneath the surface,”—that is “ beneath the cuticle.”

Now I have often had these bodies under observation, and from
what [have seen I am quite convinced that they are above the surface
of the leaves, and are indeed epidermal structures. They are found
not only on the leaves, both floating and submerged, but also on the
stem. Many of them are “ distinctly quadripartite,” but others are as
commonly met with in which the number of cells is larger—seven and
eight-celled ones being especially frequent. In none of them do I
discover any “ yellowish-brown substance,’ even with a ith and ith
Hartnack. Their contents have the appearance of ordinary proto-
plasm, though some of them seem empty. By focussing downwards, an
inner and smaller circle becomes visible, which I take to be the line
of union with the epidermis; and my observations seem to show that
in some instances the cells separate at.the apex, so as to form an open-
ing into the interior, similar to that seen at the summit of the arche-
gonia on the prothallia of Ferns.

* It is due to Col. Woodward to state that I have received a most friendly
letter from him disayowing all sympathy with the personalities of some who
have written in this controversy, in a non-scientific spirit. I have more than once
acknowledged that Mr. Tolles (though his interest lay in the construction of
object-glasses) has maintained his good humour, and I believe has argued the
point with an indefinite idea that he is right. I do not read the American
journals, and anything appearing in them concerning myself must remain un-
unswered. A recent one has been sent to me by a friend, which contains an
anonymous letter “from an eminent (so termed) microscopist of England who has
written much on the subject to a friend in this country” (America). The person
so sheltered to effect a stab in the dark, displays towards myself a petty baths
quite unparalleled, which I trust everyone else has been free from.

—————

PROCEEDINGS OF SOCIETIES. 157

My reasons for regarding these bodies as epidermal appendages
are:—1. They certainly appear naked and uncovered by any epidermal
membrane, the focus for the epidermis being lower than that for the
glands, but agreeing with that for the small inner circle referred to.
2. A favourable preparation will sometimes show them projecting over
the edge of the section, and provided with a short peduncle. 3. On
several occasions I have dissected out the growing point of a young
bud, on which were leaves in different stages of development. On these
I find a few projecting unicellular bodies, whose protoplasm was dis-
tinctly vacuolated, in a manner that seemed to foreshadow the sub-
sequent division into two, four, or more cells.

If these observations are correct—and, having repeated them so
often, I have no doubt that they are—it appears to me that Mr.
Bennett’s statements will require to be modified.

I may add further, that if the bodies under notice have any
physiological relations with the glands of “insectivorous plants,”
with which they are compared, analogy would lead us to expect them
on, rather than beneath the epidermis, as is the case with those of
Drosera, Dionea, Pinguicula, &e.

IT am, Sir, yours most respectfully,
Tuos. Hick, B.A., B.Sc.

PROCEEDINGS OF SOCIETIES.

Royat MicroscoprcaL Socrery.

; Kine’s Con.ecs, February 2, 1876.

Anniversary Meeting.—H. C. Sorby, F.R.S., President, in the
chair.

The minutes of the preceding meeting were read and confirmed.

A list of donations to the Society was read by the Secretary, and
the thanks of the meeting were voted to the donors.

The Treasurer read his Annual Statement of the accounts of the
Society for the past year, duly audited and found correct.

The President having put the motion from the chair, “That the
report of the Treasurer be received and adopted,” declared it to be
unanimously carried.

The Secretary read the Annual Report of the Council, which was
in like manner received and adopted by the meeting.

The Secretary said he had an announcement to make, which he
felt sure would be received by the Fellows with great gratification.
They had received from the President a very kind and handsome offer
to give a soirée to the Fellows of the Society on the evening of Friday,
the 21st of April. He thought this a very handsome offer on the part
of the President, who had undertaken to defray the entire expense of

158 PROCEEDINGS OF SOCIETIES,

the entertainment (which they knew the Society itself could not
afford to do), and he might add that the authorities of King’s College
had granted the use of the building for that occasion. He felt sure
that all present would show their appreciation of this offer by express-
ing their hearty thanks to the President for his kindness. He wished
also to remark that it was most desirable that as large a number of
objects as possible should be exhibited by Fellows of the Society on
that occasion. They would perhaps remember that at the old soirées
of the Society they were chiefly indebted to the makers, but it was
hoped they would personally exert themselves on the next occasion.
The evening was that of the Friday in Easter week.

The cordial thanks of the meeting to the President for his liberal
offer were then unanimously voted by acclamation.

Mr. Jas. Glaisher, F.R.S., said it gave him great pleasure to have
the opportunity of moving the hearty thanks of the Society to the
President and Officers of the Society for their services rendered to it
during the past year. As an old officer of the Society, and one who
had been intimately connected with its working in former times, as one
who knew so well the qualifications of the gentleman who now presided
over it, and as one who had so long known and worked with its
honoured Secretary (Mr. Slack) and the genial gentleman to his right
(Mr. C. Stewart), he felt that there was no better person in the room
to make this motion than himself. When they considered the result
of the Treasurer’s report, and the position in which it showed the
Society to be, that alone told them how faithful these gentlemen had
been to the trust reposed in them, and it was only those who had
similarly acted who could tell how much time and attention and care
had been given for the Society’s advantage. But it had been a painful
thing to him to see in the Journal which contained their Proceedings
the kind of correspondence which had lately appeared there, and of
which he thought they might justly feel ashamed. In all parts of the
country he had been spoken to about it, and it filled him with regret
and pain that this should be the case. Were they not all searchers
after truth? Were they not all fellow-workers for the same ends?
And could they not, therefore, carry on their correspondence in a
friendly and kindly way ? Let him go where he would—to the British
Association, or Royal Society, or elsewhere—this matter was spoken
of to him with surprise and regret, and he would urge upon them as
a Society that they should by any means, at any cost, keep from that
Journal that bore their name every letter that showed the spirit
which he had so deeply deplored. He would further only call to mind
the many hours which the Council devoted to the Society’s interests
when he asked that their services might be remembered, and that the
best and warmest thanks of the Fellows should be to their President,
to their Secretaries, and to the Council generally for their conduct of
the Society’s affairs during the past year.

Mr. B. D. Jackson seconded the motion.

Mr. Glaisher having put it to the meeting, and declared it to be
unanimously carried, expressed the great pleasure which he had

PROCEEDINGS OF SOCIETIES. 159

in presenting the cordial and unanimous thanks of the Society to the
President and Council, and in offering his best wishes to them for
the future.

The President said he had great pleasure in expressing on behalf
of the Officers and Council, as well as for himself, their thanks to the
Fellows for the kind way in which this vote of thanks had been
received. He could only say that they were always happy to do all
they could for the Society, and only wished that they could do more.

Mr. Suffolk and Mr. Palmer having been appointed scrutineers,
proceeded to the ballot of Officers and Council for the ensuing year,
and having handed in the result, the following gentlemen were declared
by the President to be duly elected:

As President.—H. C. Sorby, Esq., F.R.S.

As Vice-Presidents.—Chas. Brooke, M.A., F.R.S.; W. B. Carpenter,
M.D., F.R.S.; Rev. W. H. Dallinger; Hugh Powell, Esq.

As Treasurer.—J. W. Stephenson, F.R.A.S.

As Secretaries.—H. J. Slack, F.G.8S.; Chas. Stewart, M.R.CS.,
F.L.S.

As Council.—* Robert Braithwaite, M.D., F.L.S.; Frank Crisp,
LL.B., B.A.; John E. Ingpen, Esq.; *Emanuel Wilkins Jones,
F.R.A.S.; William T. Loy, Esq.; Henry Lawson, M.D.; *John
Millar, L.R.C.P.E., F.L.S.; *John Rigden Mummery, F.L.S.; John
Matthews, M.D.; Frederic H. Ward, M.R.C.S.; Francis H. Wenham,
C.E.; Charles F. White, Esq.

The President then delivered the Annual Address to the Society,
the subject of which was the probable limit of the powers of the
microscope consequent upon the properties of light, considered with
reference to the ultimate constitution of matter. The Address, which
was of considerable length and deep interest, was listened to with
close attention, the speaker being loudly applauded at its conclusion.
(The Address is printed at p. 105.)

Mr. Charles Brooke felt sure that all present must have listened
with great interest to the very extraordinary speculations which the
President had brought under their notice. Many of them were
speculations upon speculations, so that it was absolutely impossible in
the present state of knowledge to arrive at any definite conclusion. It
was only to be hoped that many persons might be induced to bring
their attention to this subject. He begged to move a vote of thanks to
the President for his Address, and to ask that it might be printed and
circulated in the usual way.

Dr. Matthews said he had listened with the greatest interest to the
address, in the course of which it appeared that they had been taken
upon ground hitherto absolutely untrodden, and he did not suppose it
possible that any living man could have gone much further. He had
great pleasure in seconding the vote of thanks.

Mr. H. J. Slack believed that no Society had been favoured with
an address of greater importance, from the interest of the facts and
the wide range of the suggestions, than the one to which they had

* Those with an asterisk before their names are new members.

160 PROCEEDINGS OF SOCIETIES.

listened that evening. The President could not put the motion to the
meeting himself, therefore he (Mr. Slack) would do so, and felt sure
they would pass it with acclamation. The motion was then put to the
meeting, and unanimously carried amidst hearty applause.

Annual Report of the Royal Microscopical Society.

Feb, 2, 1876.
JoHn WarE STEPHENSON IN ACCOUNT WITH THE RoyaL
Dr. MicroscoPicaL Society. Cr.
1875. £ s. d, || 1875. od a.
To Balance brought from By Cash paid for Journal 240 3 0
Bist-Dee, Asi x. 2 a lode ie G », Rent and Attendance at
,, One Year’s Dividend on King’s College Ae Ge, 13 LO
1104/7. 13s. 4d. Consols 32 17 2 » Reporter ee Dio 0
,, Composition Subscription 1010 0 » Mr. Reeves’ Salar oe coe. 0
,, Annual Subscriptions,&e. 518 18 0 » Ditto Commission ieee | ©
,, screw-tools sold .. .. 0:*2- /0 », Ray Society for 1875 .. a AL Q
, Journals sold canttak 210 0 » Fire Insurance .. .. Leet. 0
», Stationery and Printing 24 4 1
» Books’ <e. tev Seeares 8 110
5) Letty Cashy seer O) a0) 10
» Stamped Cheques... 0 4 2
», Balance remaining 31st
Dec:, 1875) awe Sede e 9
£718 4 8 £718 4 8
Jan. 29, 1876. Examined and found correct,

B. DAYDON JACKSON.
W. A. BEVINGTON.

Liprary, APPARATUS, AND COLLECTIONS.

The library, apparatus, and collections of the Society have received
during the past year a few additions specified below, and the usual
attention has been paid to their good preservation. Additional shelves
have been provided for books, but the Council have still to regret the
want of adequate space for the utilization of the library and apparatus.

The following are some of the more important books presented
during the past year.

Transactions of the Natural History Society of Northumberland and Durham.

Transactions of the Linnean Society.

Transactions of the Woolhope Club.

Transactions of the Royal Irish Academy.

Proceedings of the Royal Irish Academy.

10 Micro-photographs of Sections of Teeth, from Chas. Stodder, Esq.

Several pamphlets and papers, as well as the journals of other societies in
exchange for our own, have been announced in the Journal.

PROCEEDINGS OF SOCIETIES. 161

Boorxs PURCHASED.

Quarterly Journal of Microscopical Science.
Annals of Natural History.

Proceedings of the Royal Society.
Micrographic Dictionary. Third Edition.
Mycographia Icones Fungorum. Part 1.

APPARATUS, SLIDES, &c.

Turn-table, from C. F. Cox, Esq., U.S.A.
Hight Slides.
Box of Minerals, &c., from Mr. Hanks, of San Francisco.

A selection of these last objects have been beautifully mounted
by W. T. Loy, Esq., and placed in the Society’s cabinet.

PapPERS OF THE Session 1875-6.

The papers read before the Society during the past year will by
reason of their variety and importance bear favourable comparison
with those of any previous period. Arranging them according to
subjects, we find

Natural History.

“ Further Researches into the Life History of the Monads,” by
W. H. Dallinger and J. Drysdale, M.D., read May Ist, and con-
cluding the series commenced in 1873.

Paper on “ Bog Mosses,” by Dr. Braithwaite, finishing the series
commenced in July, 1871, the whole supplying descriptions and
figures of all the known European species.

“ A Rotifer named Melicerta (Tyro)” was described and figured
by Dr. Hudson, October 6th.

The imperfectly known “Entozoon Bucephalus polymorphus,” was
the subject of remarks by Mr. Badcock, in April, to which Mr. Slack
appended notes translated from Von Baer and other observers; and
Mr. Stewart contributed further information in the July number.
The “ Absorptive Glands of Carnivorous Plants” were described and
figured by Professor A. W. Bennett, on December 1st.

“ Perforating Proboscis Moths” were brought under the notice of
the Society by Mr. Slack (on October 6th), calling attention to a
paper read before the French Academy on certain Australian species,
throwing light upon a slide presented to the Society in April, 1874,
by Mr. McIntire, the first European observer of a perforating organ
belonging to a lepidopter.

The “ Markings of Frustulia Saxonica” formed the subject of a
note by Dr. Woodward, read on November 3rd.

The “ Variability of Form of the Forminifera, and especially of
the Cristellarians,” was elaborately illustrated in a paper by Professor
Rupert Jones, read on December Ist, and published in the ‘M. M. J.’
for February.

Apparatus and Optics.

The President (H. C. Sorby, Esq.) described “A New and Im-
proved Microscope Spectrum Apparatus, and its Applications to

162 PROCEEDINGS OF SOCIETIES.

various purposes of Research ;” on November 3rd, “ A New Method
of Measuring the Position of the Bands in Spectra,” so as to secure
uniformity of standard and accuracy of result.

“On the Principles of Testing Object-glasses by Miniatures of
Illuminated Objects examined under the Microscope,” by Dr. G. W.
Royston-Pigott, F.R.S., November 38rd; by the same author, “On
the Identical Characters of Chromatic and Spherical Aberrations,”
October 6th.

“ On the Method of obtaining Oblique Vision of Surface Structure
under the Highest Powers of the Microscope,” by F. H. Wenham,
March 3rd.

“On the Measurement of Angular Aperture,” by J. W. Stephen-
son, June 2nd.

“On Angle of Aperture in Relation to Surface Markings,” by H.
J. Slack; and by the same, May 5th, “ Notes on the Use of Mr.
Wenham’s Reflex Illuminator,” June 2nd. :

Screntiric EvEnrnes.

During the past year the Society has held two Scientific Evenings,
which have been well attended, and remarkable for the number of
interesting objects exhibited. They have also been successful in
promoting the friendly intercourse of Fellows.

Eleven gentlemen have been elected Fellows during the year, and
the Society has to regret the loss of nine ordinary and one honorary

Fellow by death.
OBITUARY.

Danret Hansury, eldest son of Daniel Bell Hanbury, of the well-
known firm of Allen, Hanburys, and Barry, was born Sept. 11,
1825. He was best known in connection with the Pharmaceutical and
Linnean Societies, of which latter he was the treasurer at the time of
his death, having performed the duties of that office for some years.
As is well known, he had assiduously and successfully directed him-
self to the study of the various vegetable products used as drugs. No
trouble, or expense, was thought by him too much to clear up the
obscurity which did, and which still does, exist respecting the origin
of many of these products. No less than sixty papers by him on such
subjects are contained in the ‘ Pharmaceutical Journal.’ His great
work was the ‘ Pharmacographia, written in conjunction with Pro-
fessor Fliickiger, published in 1874; but he was also the author of
various other essays connected with his favourite subject. He was a
valuable friend of the Pharmaceutical Society, and his exertions and
example contributed effectively to the improvement of the education
and status of chemists and druggists.

Mr. Hanbury made a very important collection of drugs and phar-
maceutical preparations. He was acquainted with several European
languages and skilful in water-colour drawing. He belonged to the
Society of Friends. He was a Fellow of the Royal and Chemical

PROCEEDINGS OF SOCIETIES. 163

Societies, and was on the Council of the former at the time of his
death, which took place at Clapham on the 4th March, 1875, from
typhoid fever supervening on an attack of inflammation. He was elected
a Fellow of this Society on the 12th June, 1867.

Henry TuRBERVILLE joined this Society on the 14th November,
1866, and died August, 1875. He devoted much time and money to
the collection of object-glasses best adapted to display lined objects,
and up to his death exhibited great interest in every optical contrivance
likely to facilitate this result.

Tuomas Henry Hennau was the eldest son of Mr. Thomas
Hennah, of the H.E.LC., and was at the time of his death, January
8th, 1876, in his fiftieth year.

He took up his residence in Brighton about twenty-five years since,
and turned his attention to photography, then in its infancy. After
carrying on a series of experiments, he entered into partnership with
Mr. Kent, and founded the firm of “ Hennah and Kent,” which from
the excellence of their productions attained a European reputation.
He was the first to introduce to Brighton the Talbotype process, and
to improve upon it so much that at the request of the Photographic
Society of London, of which he was a Council member, he detailed
his improvements in printing. A small manual on the Negative
Process, published by Mr. Hennah, is still a text-book. About twenty
years ago he became a member of the Brighton and Sussex Natural
History Society, and in 1861 was elected on the Committee, and in
1869 was made President of the Society ; in accordance with the rules
of the Society, on retiring from the Presidency he became a Vice-Presi-
dent, and held that office up to his death. The first paper communi-
cated to that Society was in April, 1870, on “Soundings made by Sir
Edward Parry in the Arctic Seas, in 1818.” During his year of office,
and mainly through his exertions, a Microscopical Section, “ which
should provide further study of objects connected with the use of the
microscope,” was added to the Society, and in September, 1870, it was
determined to continue its meetings once a month, but as a part of
the organization of the Society. (They have continued since, and the
Society meetings are bi-monthly instead of monthly.) The inaugural
address to the Microscopical Section was delivered by Mr. Hennah,
May 26, 1870, on “Systematic recent Examinations with Moderate
Powers.” So long as health and strength would allow he was a
regular attendant at the microscopical meetings, and read before the
Society papers on the following subjects: “ Gundlach’s Lenses,” Dec.
22, 1870; “ Animal Parasites—-Entozoa,’ Nov. 23, 1871; “ Palates
of Mollusca,” Feb. 22, 1872; “ Minute Crustaceans,” June 27, 1872 ;
“New Series of Lenses, by Wenham,” Sept. 26, 1872; “Scales of
Fish,” April 24, 1873; “ Illumination,” March 26, 1874.

In addition to the foregoing papers, he gave practical lessons to
the members in mounting and section cutting, and the preparation of
objects for the microscope, and contributed to the Society’s cabinet
many fine preparations made and mounted by himself.

In conjunction with Dr. Addison, F.R.S., he formed, in 1860,
a small Microscopical Club, the members of which met at each

164 PROCEEDINGS OF SOCIETIES.

other’s houses for fourteen years, during which time many interesting
subjects were discussed and worked out. His opinion on all matters
relating to the microscope was held in such esteem that almost every-
one who had worked with that instrument in Brighton during the last
twenty years is indebted to him for advice, assistance, or instruction,
which he was always ready and willing to give, even though at times
suffering from great physical debility, to the mere tyro equally with the
advanced student. In private life all who came in contact with him
speak of his uniformly affable and gentlemanly bearing, and of the
genial way in which he conveyed information to others.

He was elected a Fellow of this Society on 13th June, 1866.

The Secretaries have not been able to obtain any biographical
information concerning the following:

St. Thomas Baker, elected Dec. 11, 1867, died Oct. 14, 1875.
Frederick Barber, elected June 20, 1849, died ;
Benjamin Miller, M.R.C.8., elected Dec. 11, 1867, died
James Robinson, elected Jan. 10, 1866, died s
Robert S. Stedman, M.R.C.S., elected Jan. 14, 1857, died
William Wright, elected May 11, 1864, died April 28, 1875.

M. Mouchet, elected an Hon. Fellow Jan. 12, 1870, died ——.

Donations to the Library since January 5, 1876:

; From
Nature! + “Weekly. 2. s047 sts ge tes) a ee eee eT
Athenzoumn Weekly} si58 Gt Je PS Ae eee ee Ditto.
Society of Arts Jone sha .. Society.
Transactions of the Northumberland ‘and. Durham Natural
History society. . Vol. Viebart 2) sta | ¢. eee nee Ditto.
Journal of the Quekett Club. No. 30 sect) gel Mp aie | Hanae aaa RL LOR

The Rey. Lewis G. Mills, LL.D., was elected a Fellow of the
Society.
Watter W. REeEvEs,
Assist.-Secretary.

The Monthly Microscopical ournal, April | 1876
Fig. 1 Fig a: Fig. 3.

f :
ww

SSS
i " TO TO d
(Mh

GOO OOo

CHUIMUTANLATARUAGTAUEO AANA VANTO TATA ATTEN EATAT

MY Dallinger’s new microscope. lamp.

THE

MONTHLY MICROSCOPICAL JOURNAL.

APRIL 1, 1876.

I.—On a New Arrangement for Illuminating and Centering
with High Powers. By Rev. W. H. Daturnesr, V.P.R.MS.

(Read before the Royan Microscopican Society, March 1, 1876.)
Pirate CXXXI.

Aut who have been engaged in prolonged research, with the highest
powers at the present disposal of the microscopist, will have dis-
covered the practical value, not only of a delicate adjustment of the
Uluminating pencil, but also of an accwrate incidence of the axis
of the sub-stage combination, employed as a condenser, with that of
the object-glass itself. The value of this was very amply demon-
strated to Dr. Drysdale and myself in our protracted employment
of high powers in our Researches on the Monads. .

On the subject of delicate centering, our best text-books say but
little, and for powers beyond the y';th the methods in common use
appear to me to fail,—at least in obtaining the delicacy of result
which we have found to be possible.

Of course the theory of “centering” is that the optical axis of
the microscope should, by being prolonged, become accurately the
optical axis of the condenser. For this, in the first place, when high
powers are employed, there can be no “centering of the instrument”
in preparation for the successive reception of two or three different
powers. However delicate the workmanship, there is a displace-
ment in the transfer of powers, which, although of no moment in
the use of the th, oth, or sth, is, im practice, when the best
results are sought, of the utmost moment when a change is made
from the yjth to the s';th, or from that to the oth. Hach glass
must be centered for itself.

For such centering, a simple cap pierced with a central hole of
about the one-twentieth of an inch, and placed upon the optical com-
bination of the condenser, is often employed. But it fails wholly to
accomplish the desired end; while, as we shall presently see, the use
of a “centering glass” can only result in the accomplishment of
part of the end we know to be desirable, even if the apertures of the
diaphragms be made small enough for the highest powers.

We now employ a very accurately centered diaphragm, under
the optical combination of the condenser; this is pierced with great
care centrally, the aperture having a diameter of not more than the

VOL. XV. N

166 Transactions of the Royal Microscopical Society.

ninetieth or the hundredth of an inch. By means of the centering
screws, this is brought carefully to the centre of the field of a
moderate power. If the illuminating pencil be now carefully
manipulated, and the ;\;th objective put on, it will be found that
the image of this aperture can be brought to a focus, presenting a
central disk of light with a margin of the black diaphragm as
seen in Fig. 1, Pl. CXXXI., which presents the aspect of the
“field.”* This appears like centering, and is what we have been
usually led to consider, from the methods employed, would be such.

Now with this very minute aperture in the field take off
the jjth objective, and put on a well-corrected 3th. In all pro-
bability the disk of light will now be very eccentric, and it must be
adjusted again to the centre. This being done, we are led again
to suppose that the instrument is centered. But if now the mirror,
or still better the rectangular prism be moved to a greater or less
angle than that which gives a mere disk, a shaft of light will strike
up in the opposite direction ; and by changing the position of the
mirror, the direction of this shaft will of course be changed as in
Figs. 2 and 3, where the beam a, b is directed from opposite sides
of the mirror. This pencil of light is of course at an angle with
the plane of the diaphragm, but this effect is not readily produced
in a drawing. Now if fortune favours, by some happy movement
in the position of the lamp or prism, or both, we may change this
beam or shaft of light into an exquisite illumination extending over
half (or even more) of the field, as shown in Fig. 4; and we found,
in some measure by accident, that this minute aperture could be
made to illuminate the whole field. In this condition it presents
the appearance of a minute intensely bright sun in the exact centre
of the field, with an equal diffusion of rays all round, except that
the intensity of the light grows uniformly less as it reaches the
margin of the field. Fig. 5 is scarcely more than a diagrammatic
rendering of the effect.

Now when we had obtained this light, and used it with the 35th
and ;\5th, we were simply astonished at the beautiful results we ob-
tained—results certainly not to be secured by any other means. It
opened up structure, and displayed detail in the minute organisms
we were studying in a way which gave us hope and pleasure.

For many of our purposes—such as ‘working out the interior
structure of a monad, or studying the changes in a nucleus, or dis-
covering the earliest internal evidence of self-division—nothing was
equal to this absolutely central illumination, which gave (properly
managed) a wealth of light, a delicious field to work with, and
simply incomparable results. We found that, however it was to be
accounted for, we had fallen upon a fortunate method. But, alas!

* Of course it will be understood that the centering screws will be brought
again into requisition to perfectly centre the disk when the 25th is put on.

Illuminating, &e., with High Powers. By Rev.W.H. Dallinger. 167

its repetition was the difficulty. We had seen it—both of us—nay,
we had spent hours in the enjoyment of the profit of the light
it gave. But manipulate as we would, we could not repeat it. So
we gave it up; and then, by comparative accident, we secured it
again! What could be the secret of its appearance? It was not
the centering as usually employed, that was palpable; to all appear-
ances it was not wholly dependent upon the angle of the mirror,
for that was moved to every conceivable angle scores of times, and
for hours together, on different occasions, without result. The
amount of difficulty in securing this illumination may easily be
tested. Some of the most accomplished microscopists, who have
seen it, or to whom it has been described, have failed entirely by
ordinary means to reproduce it. At length, however, we saw
clearly that the whole secret was, after the ordinary centering was
complete, dependent upon the position of the image of the flame
upon the prism or mirror. We invariably use the flame edgeways
to the instrument, and employ a broad wick, so as to get depth of
flame; and the effect was always secured, although with great
difficulty, by minute alterations in the height, or lateral position of
the light, so that, as it appeared, a certain point in the image of the
flame was eaactly under the optical axis of the condenser. This
was so manifest to both of us, that Dr. Drysdale devised a small
piece of apparatus that would specially apply to our needs—but
only to them. We had to work always with the instrument per-
pendicular; so he had a small plane silver speculum placed under
the condenser at an angle of 45°, but so narrow that it was easy in
comparison to direct the image of the flame to the right place. But
this was nevertheless difficult of adjustment, and involved alteration
every time; for even the different height of the wick, or the least
change in the position of the lamp, was fatal to the result.

It was thus quite clear that what was needed was a lamp, with
delicate motions in all directions ; and such a lamp I have devised,
with the most satisfactory results as to the accomplishment of the
special end in view—the central illumination already described.

In Fig. 6 the lamp is figured so as to present its general
aspect. A is the reservoir and lamp; B the chimney; C the
bull’s-eye condenser; D is the pillar which carries the lamp and
condenser, separately, up and down, by means of the milled heads
E, F (which are better seen in Fig. 7) and the racks. The racks
are placed on either side of the pillar, back and front. The front
ones are indicated at G and H, Fig. 6, and by means of these the
lamp, which is fastened by an arm to a piece of metal J which
works in grooves, is carried up and down by the milled head E,
At the back of the pillar is another pair of racks, seen at K, L,
Fig. 8, which by the milled head F carry up and down a piece of
metal M, to which the arm of the bull’s-eye N is attached. By

N 2

168 Transactions of the Royal Microscopical Society.

these means the lamp and condenser have separate vertical motions.
But to accomplish the desired end we now want to be able to move
the whole pillar, Jamp, and condenser, from side to side. To accom-
plish this the pillar is fixed to a solid piece of metal O (Fig. 6),
which fits accurately into the grooves P, Q in the solid base of the
lamp T; and by means of an endless screw motion the entire pillar
and lamp and condenser are carried horizontally to the right and
left, by the milled heads R, 8, precisely as the mechanical stage of
a microscope is moved in the same directions. Thus a rectangular
motion of a delicate kind is given to the source of light; and it is
easy to find the spot on the prism or mirror where the image of
the flame best secures the central illumination desired, and shown
in Fig. 5; for the illuminating apparatus can be worked while
the eyes are engaged with the microscope. Thus instead of the
uncertainty and weariness, often ending at last in failure, of pushing
the lamp from place to place, we can with comparative ease get the
central light we need, which as a rule I find it best to get with the
ith first, and then in putting on the sth or 5th, a very slight
readjustment secures with these powers the same result.

The drawing of the apparatus is made to a seale of one-fourth,
and the letters in each point to identical parts of the instrument.

What the explanation of this illumination may be I do not
attempt to consider. The fact that this light can be got, the fact
that it can only be got with the utmost difficulty with an ordinary
lamp, and the fact of the immense value of such light in all
delicate biological investigations with high powers, every expert
microscopist may demonstrate for himself.

The value of the method is not, however, confined to the use of
absolutely central rays, although it is in this that its supreme
value consists; but it has a demonstrable value when we use larger
apertures, and the stops, for the resolution of test-objects. I have
invariably secured the finest results with the most difficult tests
by means of Powell and Lealand’s supplementary stage and small
plano-convex condenser, which sends in the beam at as large an
angle as may be desired, only from one point; therefore securing
shadows if they exist at all, or are within the compass of the power
used. But if the usual condenser* be centered and illuminated as
before described, and then the stops and apertures be carefully
employed, and. the mirror gently manipulated, and at times the
lamp altered the minutest fraction, as experience will teach, the
very best attainable results may be secured. In this way I have
resolyed with Powell and Lealand’s new immersion th Frustulia
Saaonica,t Amphipleura pellucida, Navicula rhomboides (the dots

* Tt may be well to say that it is Powell and Lealand’s sub-stage condenser
that we have used throughout.

+ Two specimens from Germany and two specimens supplied by Mr. Wheeler ;
but only the transverse stries were scen.

Illuminating, &c., with High Powers. By Rev.W.H. Dallinger. 169

beautifully clear in the part best in focus, and cross lines all over
the remainder), and Swrirella gemma (the dots being sharply
separated). These results are not given as extraordinary in them-
selves, as I believe they have been accomplished with the same
power by ordinary methods. But so far as my own experience is
concerned, the ease with which they are secured with this apparatus,
is scarcely to be compared.

I have also found this lamp of great service in the use of that
difficult piece of apparatus a vertical illuminator for opaque illu-
mination with high powers, the command possessed over the
position of the flame tending to give results not otherwise attaim-
able. ‘This is specially the case when examining dry bacteria or
monads opaquely with a 75th or y/;th.

The same to some extent will apply to the use of the szlver
side reflector. The power to dispose of the image of the flame as
may be desirable, as easily as the position of the object on the
stage of the instrument, greatly facilitates richness of illumination.

But it will be seen that all but the first result claimed for this
piece of apparatus and the method of using it, are more matters of
convenience or luxury than anything else. They can be accom-
plished without it. But to get the particular central illumination
referred to, some such apparatus must be employed ; and the value
of that illumination, in minute investigations on organic structures
with the highest powers, cannot well be over-estimated.

The instrument has been beautifully made, first for myself, and
then for Dr. Drysdale, by Mr. G. §. Wood, of the firm of (late)
Abraham and Co., Liverpool.

170 Transactions of the Royal Microscopical Society.

IIl.—The Identification of Liquid Carbonic Acid in Mineral
Cavities.

By Watrer Nort Harttey, F.C.S. (King’s College, London).
(Read before the Royau Microscoricat Sociery, March 1, 1876.)
Puate CXXXII.

In 1822 Sir Humphry Davy * investigated the contents of fluid
cavities in rock-crystals from different localities. His researches
showed that in almost every case the liquid was nearly pure water.
About four years ago [ bought from Mr. Norman, of the City
Road, a microscopic slide of quartz with fluid cavities. One good
sized cavity was readily seen with a 2-inch objective ; it exhibited
when under the microscope the shape and appearance of Fig. 1,
Pl. CXXXII. Its entire length was ='; of an inch, and its average
breadth 54; inch. The liquid at once recognized is indicated by b.
Being acquainted with the experiments of Cagniard de la Tour,
I resolved to repeat them with this specimen, and therefore,
proceeding cautiously, warmed the slide over a lamp, until it was
just too hot to be touched with comfort. On examination, the
liquid, to my surprise, was not to be seen, and the cavity under
these circumstances appeared like Fig. 2._ As the temperature to
which the fluid had been subjected was but little above that of
boiling water, I concluded that it had escaped from some minute
and invisible opening; continuing, however, to observe the object
until it became cold, I was gratified to see a sort of flickering
movement within the apparently empty space of the cavity, followed
by the replacement of the liquid, as at first. The extremely
low temperature at which only the substance assumes the liquid
state, made me at once desirous of ascertaining the exact conditions
under which the liquid is dissipated and reproduced; for the re-
searches of Professor Andrews,t “ On the Continuity of the Gaseous
and Liquid States of Matter,” have told us that at a temperature
of 88° F., or 30°-92 C., liquid carbonic acid becomes a gas, and a
pressure of even 300 or 400 atmospheres will fail to condense it to
liquidity. This temperature is called the critical point. To deter-
mine the critical point of the new fluid, immersing the slide in water
of known temperature, removing, wiping it hastily, placing it on the
microscope stage, and instantly examining it, seemed preferable to
any other mode of operating, and although other more promising
methods have been tried, the results obtained have been less
accurate.
1st Experiment. The liquid in the two cavities had disappeared
completely at 36° C.; the cavities appeared empty, but the liquid
* ‘Phil, Trans.,’ 1822, p. 367. + ‘Chem. Soc. Journ.,’ 1870, p. 74.

i
i

The Monthly Microscopical Journal, April 1.1876. PL, COT.

b

a
OO

ie

Liquid Carbonic acibin micral Cavities.

~~ 3 ann .
* n x ‘\
4 1
au -
~ ‘ ;
dea
wes j

Carbonic Acid in Mineral Cavities. By Walter N. Hartley. 171

returned after a short interval. 2nd. The liquid had totally dis-
appeared at 31°°5, and returned on cooling. 3rd. The liquid was
invisible at 31°, but returned almost immediately after contact with
the microscope stage. 4th. At 31° there was no liquid to be seen,
but it was observed to be filling in immediately afterwards. 5th.
Again at 31° did the liquid vanish. 6th. At 30°°75 the margin
of the liquid was visible, but was not so sharply defined or so high
up in the cavity as it afterwards became. 7th and 8th. On
being warmed almost to 31°, the liquid was still visible, but the
margin became more distinct: immediately afterwards. 9th. At
31°°5, liquid invisible. 10th. At 31°, upper portion of the
liquid invisible ; lower one not. 11th. The liquid invisible at 31°,
im the upper cavity, but not in the lower. 12th. At 30°-75 the
liquid was seen in the larger cavity ; the quantity, however, in-
creased to treble immediately afterwards. 13th. At 31° the upper
cavity appeared empty; the lower one full. It is evident, then,
that the critical point lies between 3U°:75 and 31° C. The critical
point of pure carbonic acid, as determined very precisely by
Andrews, lies at 30°°92 C., or very nearly 87°°7 F. Hence I
conclude that the identity of this liquid with carbonic acid is
established in a most convincing manner. It was noticeable that
in whatever position the slide was placed, the liquid generally con-
densed on the same spot. Varying the method of heating the
liquid by applying a hot wire to the surface of the quartz, I dis-
covered what was at first by no means apparent, namely, that the
upper and lower cavities were connected by a small fissure, and that
water occupied the intervening space; the upper cavity was then
seen to have the shape drawn in Fig. 3, and marked a. This
presence of water, no doubt, determined the place of condensation,
so that no matter what the position of the specimen, the carbon
dioxide always condensed on the surface of the water, because of its
adhesion to this fluid being greater than to the quartz. The
concayely curved surface of the carbon dioxide is due to adhesion to
the moist sides of the cell; the convex curvature indicating where
the two liquids are in contact is caused by the greater adhesion of
the water to the same surface. Before the specimen had been
heated in such a way as to drive the liquid from the smaller into
the larger cavity, it contained more of the carbonic acid than has
collected in it since, and it was noticed on two or three occasions,
that the action of heat was to diminish the gas-bubble very rapidly,
by expansion of the liquid, until it had the appearance shown in
Fig. 4; the bubble then as quickly increased in size, by contraction
of the liquid to its original dimensions, when the source of heat was
removed ; likewise, when the heat was continued, the gas-bubble
increased by vaporization of the liquid, as in Fig. 2. The appear-
ance caused by the expansion and contraction resembled the dilata-

172 Transactions of the Royal Microscopical Society.

tion and contraction of the pupil of the eye. Since the connection
between the cavities has been made by excessive heating, the
expansion and contraction cannot be shown; the liquid at once
begins to vaporize, when warmed, and even boils, as is shown in
Fig. 4. The following observation of Thilorier explains this.
When a tube containing liquid carbonic acid is one-third full, at
0° C., it constitutes a retrograde thermometer, in which increase of
temperature is shown by diminished volume, consequent on the
vaporization of the liquid, and vice versi; while if the tube be
two-thirds full, a normal thermometer of great sensitiveness is the
result, the liquid expanding by heat in this case.*

Very careful observation several times repeated has shown that
on the approach of a warm substance, causing the liquid in the
larger cavity to be vaporized gradually, the curvature of the surface
in contact with the gas becomes reduced very much, and at the
same time rendered less plainly visible, as shown by 8, Fig. 3.

There was also noticed a faint flickering shadow in the point
of the cavity, when the liquid was about to condense. Professor
Andrews has noticed such effects during the vaporization and con-
densation of liquid carbonic acid. In the same section of quartz
there were observed upwards of fourteen smaller cavities, containing
liquid carbonic acid, together with water in different proportions.
There are two such cayities shown in Fig. 1; in each case the space
marked @ contains carbonic acid as gas; b, the same substance
liquefied and floating on the water, which, being indicated by «, is
seen to be occupying the remaining space.

According to Thilorier, the specific gravity of liquid carbonic
acid is 0°83 at 0° C.,, and 0°6 at 30° C., water bemg taken as
unity. The constant position of this liquid in the cells being
uppermost is in accordance with this.

Volatile fluids have been noticed in mineral cavities by Sir
David Brewster,t by the late Mr. Alexander Bryson,{ and by
Messrs. Sorby and Butler, who came to the conclusion that the
liquid in a particular cavity in a sapphire was really liquid carbonic
acid, because it possessed a remarkable rate of expansion between
0° and 80°C. Thilorier has shown that the expansion of liquid
carbon dioxide between 0° and 30° C. is such, that 100 volumes
become 145. Sorby found that 100 volumes of the liquid he ex-
amined became 150 at 30°C., 174 at 31°C., and 217 at 32° C.§

Through the kindness of Mr. Butler, I have had the advantage
of examining some of the best specimens from his unique collection
of stones with fluid cavities, and I have no doubt that the con-

* ‘Ann. Chim. Phys. [2], lx. 249.
+ ‘Trans. Royal Society of Edinburgh,’ vol. x., p. 1, 1823.
t ‘Proceedings of the Royal Society of Edinburgh,’ 1860-1.

§ ‘Proce. Royal Society,’ vol. xvii., p. 299; also ‘Transactions of the Royal
Microscopical Society,’ vol. i., p. 222.

TS ee ee ee HS ae

Carbonic Acid in Mineral Cavities. By Walter N. Hartley. 173

clusion which he and Mr. Sorby arrived at was a just one. By a
very simple contrivance I have been enabled to detect the presence
of liquid carbonic acid in many very small cavities containing water.
This consists of a glass tube about three-eighths of an inch in dia-
meter and twelve inches long ; it is drawn out to a jet at one end of
about one-sixteenth of an inch aperture, the jet being bent at an
obtuse angle. To prevent the glass being softened and bending
when heated, it is covered for four inches in its central part by a
piece of brass tube which slides on not too easily. The straight
end of the tube is somewhat pointed, and passes through an india-
rubber cork fitting into a universal joint upon a stand having a
sliding motion in the upright so that it may be raised or lowered
at will. This end of the glass tube which has passed through the
cork has a piece of india-rubber tube slipped over it fifteen inches
long, and to this is attached a ball syringe whereby air may be
drawn in and discharged again. By heating the metal tube with
a spirit lamp or Bunsen burner, the air discharged will be heated
and may be directed on to the object while undergoing examination
beneath the microscope without any displacement whatever, by
which means a high power may be used for the examination of
small cavities. By noticing the number of ballfuls of air necessary
to vaporize a known specimen of carbonic acid, one may, if these be
sufficient to vaporize the liquid in small cavities, be certain that
the temperature is not greatly different. It is easy to demonstrate
the presence of small quantities of carbonic acid mixed with water
in cavities no larger that 759 of an inch in their greatest dia-
meter.

After carbonic acid has passed its critical temperature, if it be
cooled suddenly it condenses with a motion resembling ebullition.
This is best seen-in deep cavities. Messrs. Sorby and Butler have
observed this phenomenon.* Having attentively studied it in dif-
ferent cavities, I have come to conclusions as to the meaning of it.
When the gas is chilled, a sort of mist forms throughout the space;
the individual spherules of this mist grow so large that they begin
to touch each other, to coalesce, and to gravitate. They of course
at the same time entangle gas, and as they descend to the lower
part of the cavity the spherules of gas (bubbles) take an opposite
direction ; consequently when a portion of the liquid has collected
at the lower end and gas at the upper, there are showers of liquid
descending into and streams of bubbles rising out of the liquid.
In two or three seconds the movements have ceased. In Figs. 5
and 6 are given representations of a fluid cavity im topaz belong-
ing to Mr. James Bryson, of Edinburgh, to whom I am much
indebted for allowing me to examine some of his valuable speci-
mens. When at a temperature two or three degrees below the

* ‘Monthly Microscopical Journal,’ yol. i., p. 222.

174 Transactions of the Royal Microscopical Society.

critical point, the liquid has the appearance seen in Fig. 5, but the
boiling is shown in Fig. 6—the spherules called gas and liquid are
passing in the direction of the arrows nearest them. ‘The drawing,
Fig. 7, represents a cavity seen in one of my specimens of quartz ;
the contents are undergoing the apparent boiling. The conditions
favouring this singular mode of condensation seem to be, first, that
the greater part of the carbonic acid shall be in the liquefied state
at ordinary temperatures so that the liquid expands greatly on
approaching the critical point; second, that the cooling shall be
sudden.

Cavities containing liquefied carbonic acid may be divided into
two classes, wet and dry cavities, according to the absence or presence
of water. The appearance of the liquid in a dry cavity differs much
from that in a wet one. ‘Thus in a dry cavity the liquid presents
a convexly curved surface to the gas, in a moist one a concave
surface. While the carbonic acid in sapphires and rubies seems
generally to be dry, that met with in quartz and other minerals is
more frequently wet.

Another means of ascertaining the critical temperature of the
liquid in fluid cavities was resorted to. It consisted in making a
water-tight cell with glass sides, which would contain besides the
mineral under examination the bulb of a small thermometer three
inches in length and graduated into one-tenths of a degree Centi-
grade, between 29° and 35° C. An inlet and outlet tube of india-
rubber conveyed a stream of warm water, forced through the cell
from a small flask by means of the pressure of a large india-rubber
finger-pump or syringe. The entrance and exit for air to and from
the syringe was by valves in different branches of a T tube.

The walls of the cell were made by boring a hole an inch in
diameter through an india-rubber cork of the diameter of 1} inch.
Two perforations one-eighth of an inch in diameter were made in
the side of this to admit the water tubes, and a third for fixing the
thermometer in. The glass slides placed top and bottom of the
ring were firmly fixed by passing stout india-rubber bands over
them. When the cell was placed on the microscope stage, a power-
ful Coddington lens was so arranged in position near the thermo-
meter that without the slightest movement the cavities could be
watched through the microscope with the left eye, and simulta-
neously the mercury in the thermometer with the right. The
cavity under examination was so arranged that it appeared just
upon the edge of the lens. Admirable though this arrangement
seems, it does not answer quite so well as one might expect. ‘The
volume of water in the cell is so small, that it changes temperature
more readily than the slowly conducting mineral.

My original plan of immersing the mineral in a considerable
volume of water at temperatures just above and below the critical

Carbonic Acid in Mineral Cavities. By Walter N. Hartley. 175

point, may be improved upon by placing the specimen in a glass
cell with parallel sides and immersing this in water of known tem-
perature; on removing this for examination, the sides of the cell
may be wiped dry without fear of the mineral losing an appreciable
amount of heat. Being now engaged in the study of other rocks
and minerals, details regarding these had better be left for another
communication. I have elsewhere shown* the nature of the chemi-
eal reaction which would most probably yield quartz crystals with
carbonic acid cavities, but this explanation could not be applied to
the formation of topaz and sapphire.

* “Journal of the Chemical Society,’ February 1876.

176 Transactions of the Royal Microscopical Society.

Ill.—On some Structures in Obsidian, Perlite, and Leucite.
By Frank Rurtzy, F.G.8. (H.M. Geological Survey).
(Read before the Royau Microscorican Socrery, March 1, 1876.)

Piates CX XXIII. anp CXXXIYV.

In this paper I shall eudeavour to demonstrate certain peculiar
structures in spherulitic obsidian and leucite which appear to be,
in some respects, analogous; and an explanation will also be
attempted of the spheroidal structure wach characterizes the
vitreous rocks known as Perlites.

So far back as 1857 your President, Mr. Sorby, was at work
with his microscope upon the pitchstones of Arran. Since that
time Vogelsang, Zirkel, Allport, and others have made very con-
siderable additions to our knowledge of the minute structures
which rocks of this class contain.

The section of obsidian which I am about to describe was cut
from a specimen collected by my friend, Mr. J. W. Judd, from a
lava flow in the Isle of Lipari. The mode of occurrence of this
lava stream is described in his “ Contributions to the Study of
Volcanos,” published in the ‘Geological Magazine, 1875. The
specimen is a grey glass, but when seen in moderately thick pieces
by reflected light it appears black. Through this glass run parallel
bands of white spherules, which are often elongated, and in most
cases have coalesced so as to form either continuous parallel-sided
bands (approximately cylindrical) or moniliform strings. Isolated
spherules also occur in the specimen, and sometimes adhere to the
sides of the spherulitic bands, as shown in Fig. 8, Pl. CXXXIII.
The isolated spherules have a distinctly radiate structure, which in
the bands formed of coalesced spherules is almost absent. Both
the isolated spherules and the spherulitic batids are surrounded by
a broad external crust, which by transmitted light appears of a
reddish-brown colour, and is but feebly translucent, while by
reflected light it looks almost snow-white. Within this lies
granular or crystalline, and in some cases radiately fibrous matter,
which in many instances exhibits a reddish, rusty colour, both by
reflected and by transmitted light ; while in others, although rust-
coloured by transmitted light, it appears white or greyish white
when viewed as an opaque object. At times this inner substance is
sharply separated from the cortical layer by a thin, transparent,
vitreous band. In the spherulitic bands there are usually other
innermost bands which are more translucent and less rusty in appear-
ance than the intermediate ones, and along these inner cores there
frequently run lines of almost opaque bodies, giving, as a rule,

The Monthly Microscopical Journal Aprl.1876. Pl .CXXXIL.:

4 R

Structuresin Obsidian and Leucite.

z

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MEN ot , i Ee
1 OR be ;

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Structures in Obsidian, Perlite, and Leucite. By F. Rutley. 177

sections similar to those which an octahedron would yield (Fig. 8).
They are often feebly translucent towards their margins. This
probably results from peroxidation of the protoxide of iron which
the mineral, if magnetite, would contain. I believe that these
crystals are magnetite altered at their margins into limonite
or possibly in some cases hematite. Lasaulx has noted the occur-
rence, in the altered lavas of Auvergne, of microscopic pseudomorphs
of hydrated oxide of iron after magnetite, in distinct octahedra of
a brownish-red colour and translucent.* I merely record this point
because, from the slight marginal translucency of these crystals,
some doubt might be experienced as to whether or not they
really represent magnetite. The hand specimen, from which the
section was cut, attracts the magnetic needle, and seems, at certain
spots, to repel it also to a very slight extent. Fig. 12 shows
similar, but much smaller crystals, which are plentifully dissemi-
nated in the crystal of leucite, presently to be described, but they
are so minute, as a rule, that unless magnified five or six hundred
diameters they appear to be mere amorphous specks. At various
points along the spherulitic bands in the obsidian, minute tube-like
bodies may be seen under the microscope, with a quite low magni-
fying power (such as 20 diameters). ‘The tube-like bodies appear
to emanate from sometimes one, sometimes the other, of the inner
layers of the spherulitic bands, pass through the outer zone, and
protrude, often for a considerable distance, into the glassy, colour-
less obsidian. Sometimes they are seen to terminate in a rounded
end, like the end of a test-tube (Figs. 4 and 5), but they are
often cut off by the planes of section, which in some cases gives
them the appearance of ending abruptly. After a careful examina-
tion of these forms, I have come to the conclusion that they are
not tubes, but solid rods of glass. An inspection of the form shown
in Fig. 6 may serve to render this point more apparent. Here,
one of these rods is seen to pass through the cortical zone of
a spherulitic band, and to completely surround an outlying, isolated
spherule. Now there is no reason to doubt that this clear, glassy
ring, which appears as a mere girdle in the section, is in reality a
slice through a vitreous envelope which completely encased the
spherule. Had this rod been a tube, and the envelope of the
spherule merely a bulbous continuation of that tube, it is manifest
that, whether vacuous or filled with a gas or a liquid, the enyeloped
spherule would infallibly have stripped out during the process of
grinding the section ; and even assuming that a vacuum existed
between the cup and the piece of the spherule, and that by atmo-
spheric pressure or by some accident it had remained 7 situ, there
is little doubt but that some small amount of emery mud would have
* “Neues Jahrb. f, Min.,’ 1870, p. 695.

178 Transactions of the Royal Microscopical Society.

worked into the line of contact, and thus attest the presence of a
vacuity. Of this there is not the slightest trace, the cincture of the
spherule being perfectly clear and glassy. Some of these glass
rods issue at right angles from the spherulitic bands, others
obliquely ; some are more or less bent, occasionally almost at a
right angle, as in Fig. 5. Here and there two rods may be
seen to anastomose and pass out into the surrounding obsidian as
a single rod. Fig. 7 represents a stream of granular matter
projected through the cortical zone of a spherulitic band into the
surrounding glass. Fig. 1 is a straight cylinder or elongated
glass rod magnified 225 diameters. It has apparently been
severed at two points equidistant from the ends, thus giving
rise to three cylindrical forms, the two terminal ones being some-
what thicker than that in the middle. It is, however, possible
that this supposition is incorrect, and that they are three elongated
lacune of glass. If so, why do they lie in a perfectly straight
line? a line parallel in direction with the larger spherulitic bands,
i.e. in the direction of the lava flow. ‘The tension in the direction
of, and consequent upon, the flow of the molten matter, may even
have sufficed to elongate and sever this rod. Has not this tension,
coupled with strain necessarily more or less rectangularly situated
to the direction of flow, also caused the cylindrical extrusions of
glass from the spherulitic bands, or do the latter phenomena
depend upon the contraction of the bands themselves, caused by an
imperfect attempt at crystallization ? Although, from the fact that
these extruded glass rods are often curved in opposite directions, it
may be assumed that they were uninfluenced by the direction of
the lava flow, we must also bear in mind that they pass through
the outer zones of the spherulitic bands in diverse directions, and
consequently often issued more or less obliquely into the surround-
ing obsidian, and equal pressure upon an overlying surface would
tend to curve them still more in the directions in which they
respectively issued. It is probable that their solidification was
‘ very rapid. The innermost core in the spherulitic bands is usually
doubly refracting ; hence we may assume that devitrification was
set up at certain points or along certain lines, these points being
determined by the presence of some trifling impurity, such as a
minute granule or crystal of magnetite. This devitrification results
from the development of crystalline structure; the crystalline
bands probably enveloped minute lacune of molten glass, and upon
solidification contraction of the cryptocrystalline mass ensued, the
outer crust of the bands became fissured, and the lacunze of glass
finding an outlet from the internal pressure of the band, escaped
through the cracks in the rod-like forms in which we now see
them. Finally, solidification of the magma ensued; but it is
probable that these different processes took place almost syn-

Oe

eh at ae

Structures in Obsidian, Perlite, and Leucite. By F. Rutley. 179

chronously. This appears to me to be the most plausible way in
which to account for the phenomena which occur in the section
which we have been considering.

The following translation from Zirkel’s ‘Mikroskopische Bes-
chaffenheit der Mineralian u. Gesteine’ (p. 75) may here prove
interesting, as indicating the existence of structures somewhat similar
to those described, but due to a different cause :

“Some of the more rare enclosures of glass which occur within
a glass mass are peculiar. They may be recognized from the fact
that a tolerably concentric circle usually surrounds a dark, mostly
spherical cavity, but lies at some distance around it, the intermediate
part also consisting of glass which is as a rule identical with the
surrounding glass; it is, however, at times clearer or darker. These
glass enclosures in glass are probably due to a gas-bubble, sur-
rounded by a thin envelope of molten matter, having broken loose
from some spot and after reaching an adjacent part of the magma
becoming fixed. That this is in fact the case, is proved by the
circumstance that at times the matter surrounding the bubble has
developed a finely fibrous structure to a certain extent around its
zone of attachment in a somewhat radial manner.”

A few points will now be noticed in connection with the micro-
scopic structure so characteristic of Perlites: rocks which are closely
related to pitchstone and obsidian. In these rocks a very peculiar,
concentric, shaly structure exists, which has been described by Zirkel,
Rosenbtisch, and other observers. In some perlites, microliths,
trichites, crystals of magnesian mica and felspars, and also small
spherules, very similar to those just described, occur. Some of the
latter are surrounded by a clear girdle, like that shown in the
Lipari obsidian, Fig. 6. It is possible that the glassy girdles of
these isolated spherules may merely represent a structural differen-
tiation, and that their union with the cylindrical processes may only
. be an accidental circumstance ; their probably identical constitution
and synchronous development having favoured their coalescence,
so that no perceptible demarcation exists between them. Under
the microscope a distinct fluxion texture is seen in many of
the perlites, being rendered evident by granular matter and micro-
liths lying in more or less continuous streams. These streams,
which thus apparently represent fluxion planes, are traversed at
all angles by fine fissures, which often intersect one another, and in
thin sections I have not yet been able to find any instances in
which these fissures traverse the perlitic spheroids, although the
fluxion structure cuts across them in a very marked manner. On
the contrary, I find that the spheroids are packed between these
fissures, and there is even evidence that in places their forms have
been affected or modified by the fissures, since they sometimes
appear to be more or less compressed where they come in contact

VOL. XV. i)

180 Transactions of the Royal Microscopical Society.

with one of these cracks (Pl. CXXXIV.). Have we not here a struc-
ture analogous to the spheroidal structure sometimes seen in prisms
of basalt ? The divisional planes in the basalt, which by their inter-
sections give rise to the prismatic forms, are assumed to result from
shrinkage or contraction consequent upon solidification. These less
regular little cracks in the perlites are unquestionably due to the
same cause. In a paper, read the other day, by the Rey. T. G.
Bonney, before the Geological Society, it was pointed out in a very
clear manner that the spheroidal structure in basalt results also
from contraction on cooling. Surely then if these spheroidal forms
in basalt are not intersected by the planes which divide the basaltic
prisms, but are enclosed by those planes, the prism-planes were the
first formed, while the spheroidal structure resulted from subsequent
cooling taking place along those planes. If this be a right inter-
pretation, I believe that we have here, in these perlites, a clearly
parallel case, and that the explanation of the spheroidal structure
in basalt is equally applicable to this, hitherto unexplained, structure
in perlite.

I shall now point out those structures which seem most worthy of
remark in the section of a crystal of leucite which I have recently
examined. It is imbedded in a somewhat opaque lava which also

contains crystals of plagioclase, &c., and was procured from one of —

the lava streams of Vesuvius. Fig. 2 represents a few of many
minute enclosures, some of which are of very irregular form;
they have broad, dark margins, and seem to be devoid of bubbles,
so that I think they may possibly be glass lacune. Fig. 3 is
approximately a straight cylinder, and either contains a plug of
granular matter or else is incrusted with it. Fig. 10 is a ball
of granular matter apparently perforated by a microlith or small
eylinder (similar figures are given in Zirkel’s ‘Mik. Beschaff.
d. Min. u. Gest., p. 75). Fig. 11 is a similar cylinder free from
granular matter. I speak of these bodies as cylinders, because
I am uncertain whether they are hollow or solid, but I think that
they are solid. Now the question arises whether Fig. 3 is simply
a version of Fig. 11, but containing a plug of granular ma-
terial, and if so, is Fig. 10 a similar cylinder to Fig. 3, but with
a bulb blown in its centre, just as we might heat a piece of
glass tubing and blow a bulb at that point? If merely an
incrustation around a rod, why is it that the rod is not equably
incrusted throughout its entire length? Fig. 10 is not an ex-
ceptional example, there are others precisely similar, lying close
by it.in the same section. If this be an instance of capricious
incrustation, we need hardly be surprised at it, when we consider
the singular way in which we sometimes find chlorite investing one

particular face of a quartz crystal in preference to the others.

Probably, however, there is no caprice in. nature, and phenomena

ne ee re

Structures in Obsidian, Perlite, and Leucite. By F. Rutley. 181

of this class may be governed by laws or brought about by con-
ditions of which we are yet ignorant. It may be that Fig. 10
represents an originally spherical evvity, around which granular
matter segregated, and that, from pressure, .the spherical cavity
has become elongated and has been protruded through the gra-
nular envelope as a straight cylinder. Figs. 9, 13°and 14 are
straight filiform cylinders, which have this peculiarity, that they
appear invariably to terminate in little nodes cf granular matter.*
In Fig. 9 this granular matter either lies within or inerusts the
cylinder. Are these nodes of granular matter discharges which
have taken place from the ends of the cylinders? (if so, the
cylinders are hollow)—or are they merely segregations which have
formed on the ends of the rods? I submit these questions to
the members of this Society, in the hope that they may be able to
solve them. é

Having now described these structures, it may be well tosum ap
the conclusions to be derived from them.

i. That the cylindrical processes extruded from the spherulitic
bands in the obsidian of Lipari are solid rods of glass.

ii. That the spherules in this obsidian have resulted from the
development of imperfect crystallization around minute foreign
bodies, such as granules of magnetite &c., causing devitrification of
the otherwise clear glass of the obsidian.

i. That upon the contraction of this cryptocrystalline mass
pressure was exerted upon small lacune of molten glass which were
enveloped in it, and that fissures, produced in the outer crust of the
spherulitic bands by the same contractile force, afforded channels
of egress for this still fluid matter which after extrusion rapidly
solidified.

iv. That the main glassy magma of the obsidian solidified last,
but that the interval which elapsed between crystallization around
nuclei, extrusion of glass rods, and solidification of the magma, was
a very brief one.

v. That in the crystal of leucite described, there are structures
which bear some analogy to those in the spherulitic obsidian.

vi. That the zoned spheroids in perlite are never, so far as
I have ascertained, traversed by any fissures of even microscopic
importance, but that, on the contrary, the spheroids always lie
between these planes of fission.

vi. That the foregoing fact indicates a close relationship be-
tween this structure and the spheroidal structure sometimes seen
in basalt, and that the two structures are probably due to the same
cause.

* So much has already been done by Vom Rath, Wedding, Zirkel, Des Cloiseaux,
and others, in the examination of leucite, that it is quite possible that they may
have observed similar structures; but of this I have seen no record.

o 2

182 Transactions of the Royal Microscopical Society.

One or two analyses of obsidian and leucite are appended, to-
gether with a few remarks thereon.

ANALYSIS OF OBSIDIAN FROM LIPARI.
Abich, ‘ Vulk. Ersch.,’ 1841, 62 and 84,

Silica .. SN cs hese Se eae 26: 4 50h ee OD
Alumina “ees - 1k kG eek ann een eT
Sesquioxide’ofiiron’ §.. 9 <2 G0)..." ee
Protoxide of iron si RSaP.. ace) dg see —
WaAmMe:, on). Gite co ees, . ie holy ae ae ae 0°12
Maienesia 8. ee ere
Potashiiiy 20a suk, Oe) OS DO ee oral:
Sod a ince) clelemetsnily Es led pebceecicccene 3°88
Waterjand loss' -<:. «ps. c.) Jos, sche Senne Cee 0°22
Chlorine wage 20 AEE ORO Oe eee Ova

99-67

- Although this analysis indicates that protoxide of iron is absent,
yet one of an Indian obsidian, by Damour, shows 10°52 of the
protoxide, but an absence of sesquioxide of iron.

When we consider that the protoxide of iron present in magne-
tite does not amount to more than about 30 per cent., and when
we also consider that the crystals in the spherulitic obsidian from
Lipari are partly altered or entirely altered into peroxide, either as
hematite or limonite, we need not be surprised that the above
analysis yields no protoxide of iron ; and even if the magnetite were
only slightly decomposed, its sparse dissemination in this rock
would render the presence of protoxide of iron merely discernible

in traces.
ANALYSES OF LEUCITE FROM VESUVIUS.

Klaproth. Bischof.
Silica 25. “ss so, ake se tee | OO TO
Alumina we ew ted |S ORS 24620 Ta ese
WGimMes eyes ss pede Yh tet face —_ co eNO
Soda Nc yate-e uee the Eel ads Gaulinste — ais, epee
Potash 2-2. 2s es se) pet OL SOL Been ned
Sesquioxide ofiron .. .. .. — aa nO ALE
Watery sd )t:artectasiy iiagie — iat wae ROHS

Comparing these with the foregoing analysis of obsidian, it will
be seen that the chief constituents of leucite and of obsidian are the
same, but that the mineral and the rock vary somewhat in their per-
centage composition. Surely this identity of qualitative composition
may to some extent account for the similarity which appears to
exist between the structures described in this paper.

Before we finally quit this subject, let me once more direct
your attention to the section of spherulitic obsidian. To my mind,
we have here not merely a microscopic section, but a geological
section of considerable significance. Let us suppose that the
cortical zone of our spherulitic band is about 25 miles in thickness ;

Structures in Obsidian, Perlite, and Leucite. By F. Rutley. 183

let us suppose that the underlying cryptocrystalline layer repre-
sents a mass of granite or other rock matter, once in a state of
fusion, and which upon solidification shrank nearly 10 per cent. of
its original bulk, as Bischof has shown that trachytic rocks do in
passing from a vitreous to a crystalline state; let us also imagine
that the little lacune of molten vitreous matter enveloped within
this cryptocrystalline mass represent reservoirs of molten matter
of considerable size, and that the glass rods extruded through the
cortical portion of the spherulitic crust are dykes, which have been
forced through pre-existing fissures by the contractile force of
matter passing from the molten to the solid state ; and we have here
a somewhat correct rendering, I believe, of the way in which many
great geological phenomena have taken place. Nature makes no
difference between the most colossal and the most minute portions
of her work. The contraction which takes place upon the solidifica-
tion of a cubic inch of rock from the molten state is but a fraction,
which if multiplied, will give the contraction of cubic miles of
similar rock solidifymg under like circumstances. The cubic inch
is but the cubic mile in miniature, and we may even hold within
our hands a small fragment of stone whose minute structure
represents more truly than books can tell, or than diagrams can
depict, the nature of some of those changes which are ever going
on beneath our feet; of which, indeed, we should know but little,
save for volcanic eruptions and those hardened weather-beaten
wrecks of once deep-seated molten masses of rock, which are now
exposed by denudation and within the reach of our hammers.

() 1tyy

IV.—On the Aperture of Object-glasses. By F. H. Wennam.

Tue number of degrees that include a pencil of light radiating
from one single point from the focus of a microscope object-glass,
represents the true angle of aperture.

In order to obtain accurate results, the light indicating the
admitted degrees should be confined to a mere point or line situated
in that focus.

In the diagram the angles are the result of ascertained dimensions
from a known immersion object-glass, as follows :—Acting diameter
of front lens, -033; focal distance from the front surface, 025,
with a width of field of ‘020, or 35 inch. With correction adjusted,
the resulting angle from central focal point is 663°, each ray giving
a distinct image. In order to determine the direction of the outer
rays by the usual sector method, a narrow slit must be set in the focus:
the extreme light of the true aperture will pass through from a.

Let the slit now be opened out to ;'5 of an inch, so as to admit
the effective oblique pencils embracing the entire field of view.
Light will then enter from direction b. This ray will also show a
distinct image, and an aperture of 93° will now be indicated instead

On Zeiss’ 3's5th Immersion. By W. J. Hickie. 185

of the former 663. This excess of angle is a false quantity,
because it does not come as a radiant from one single position in the
axial focal point, but from other lateral rays of the marginal foci.

From this it may be inferred that unless precautions have been
taken to exclude these lateral pencils, all measurements for ascer-
taining large apertures have hitherto been erroneous, and far in
excess of the true pencil from a single radiant point ; and this source
of error will exist from the same cause, whether the measurement
is taken by means of the usual convenient sector, or what may be
termed the telescope method, of obtaining distinct distant images
with a suitable eye-piece arrangement.

I disclaim invidious intentions in putting forth the expression,
that the apertures of high-power object-glasses published in the lists
of opticians are all wrong, and shall not quote any particular one
as an example. If this is a scientific fact, let it be fairly discussed
as such, without rancour or personality. The question is a simple
one, and I cannot at present see that I am in error in a theory
clearly proved by point of fact measurement.

The result may always be verified by the measurement of the
focal distance (suitably corrected by the adjustment) and size of
the working portion of the front lens, through which rays are
admitted. Many will be surprised to find how small this portion
is. In high powers it may be defined by screwing the object-glass
in the place of the achromatic condenser, and the diameter of the
spot measured with a micrometer, used with a low power. The
front of the object-glass should have a drop of milk dried upon it
to serve as a screen, or if the lens is flush with the setting, a piece
of thin covering glass, greyed on one side, may be laid upon it, by
means of which the proper light area can be determined having
a definite margin.

V.—On Zeiss’ 33th Immersion. By W. J. Hicxts, M.A.

Axout the 18th of last October I obtained from Zeiss, of Jena, one
of his ssths (No. 3 immersion), and during the first week in
January the same maker forwarded two others, which he had
completed only a few days before. On the evening of the same
day all three were submitted to a trial of their capabilities. In the
account I am about to give, I shall indicate the three »'sths then
examined by the letters A, B, C, where A denotes the objective
first sent, while those sent in January are denoted by the letters
B and C. As A had been in constant use for more than two
months, I had had ample opportunity of making myself acquainted
with all the peculiarities of this description of lens, as also with the

186 On Zeiss’ 3'3th Immersion. By W. J. Hickie.

_ exact adjustment of the correction-screw required for a considerable
number of the most trying tests. Having carefully compared these
glasses, one with another, and likewise with Seibert’s sth and
Schieck’s (so-called) 5th, both immersions, I left off with a strong
impression that the one I have called C was markedly superior to
the other two, reserving the more rigid scrutiny for the following
morning. As my habit is, when I have any task of this kind
requiring more than ordinary carefulness, to work during the
morning hours, and in a darkened room, it gave rise in this
instance to a somewhat curious accident. Having arranged the
lenses on a sideboard, and, as I thought, in the order in which I
have named them, i.e. A, B, C, I renewed the examination of the
preceding evening, but this time with the utmost care and exaet-
ness. On this occasion, however, to my great disgust, the decidedly
best glass appeared to be B; and repeated trials only made its
superiority more and more evident. Unwilling to believe that I
could have been so maladroit the night before in a matter so

straightforward as this, I proceeded to light a candle, and the

mystery was solved at once. The glass I had taken up second on
each occasion turned out to be C, which had somehow got placed
second in order instead of third. As a matter of course, I tried
them all again the morning after that; but the result remained
the same, and C again proved itself to be the best glass all through.
A came next in order of merit, and then, but at a considerable
interval, B. It is therefore of C that I shall have to speak in this
present paper, as the other two passed immediately afterwards into
other hands. I may add, that the maker had himself compared
them very carefully, and had been unable, as he declared to me, to
detect any difference whatever. Before proceeding further, I will

mention briefly the most salient features of this class of objective..

The workmanship is conspicuous above all German objectives which
I have seen for its extreme neatness, and may be examined all over
with a hand-magnifier. There is no extravagant disparity between
the breadth of the front lens and the breadth of the hindermost
lens ; upon which point I shall have something to say later on. Its
working distance is remarkably great. But this is characteristic of
all Zeiss’ objectives. It has abundance of light, even with deep
eye-pieces. This C now in my possession bears Ross’ EK eye-piece,
with very little ill effect beyond becoming more difficult to manipu-
late. It also has complete flatness of field, and is wondrously
sensitive to the slightest ehange of the correction-screw. The
following instance will suffice to show this. On Stauroneis spicula,
when placed vertical, and with the correction-screw set at 113, the
transverse striz are altogether invisible; but when the correction-
screw is at 124, the same striz are brought into view with perfect
clearness! The serew-collar, instead of moving the front lens, as

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:

On Zeiss’ J,th Immersion. By W. J. Hickie. 187

is usually the case, moves the hindermost combination; in which
arrangement there are certain advantages: it decentres the com-
binations much less, as is plainly apparent when this species of
objective is compared with objectives on the old plan; the object .
also remains in sight while the adjustment is being altered, and
there is at the same time less danger of smashing the covering
glass of the slide. It is also well seen how carefully it has been
corrected generally, and through all the divisions of the adjust-
ment, from 5 to 16 inclusive; and that even at 15,—and I have
only two slides (duplicates) that require so extravagant an adjust-
ment,—its definition is both clear and beautiful. Beyond that it
begins to show a little colour. This range, however, is amply
sufficient for all reasonable purposes.

I must not omit to mention that certain mechanical alterations
have been introduced into his objectives of this year, which did not
appear in his earlier issues. The figures and division-lines con-
nected with the correction-screw have been enlarged in size, to suit
those who work by lamplight. In his earlier objectives these were
so minute, as to make it often a difficult task to discover what was
the precise adjustment one had fixed upon as best suited for the
particular object under examination. The part containing the
figuring and correction-screw has been slightly depressed, so as to
keep it more out of the way of one’s fingers; and the screw-collar
itself has been made to move more stiffly. In his older objectives
this part was sometimes so loose, that the proper adjustment often
got shifted in handling, which made the glass appear to work
badly. These alterations I cannot but regard as improvements,
the more so as they were introduced at my suggestion. |

I am here reminded of certain recent statements respecting the
magnification of Zeiss’ objectives, which seem to require some
notice. Dr. Griffin*® states the magnification of Zeiss’ } inch, with
a B eye-piece, to be x 640, and the magnification of his +; inch
(dry), with the same eye-piece, to be x 875; whereas, if we turn to
Zeiss’ catalogue, we find the magnification of the 3th, with the
second eye-piece, set down at x 330, and that of his dryt ~,th
set down at x 500. So, again, one writer in the ‘M.M. J.’ states
the initial magnification of Zeiss’ z's inch to be x 1250, and is
contradicted by another, who appeals to Zeiss’ own catalogue in
proof that its initial magnification is only x 680. ~ In both cases

* *M.M.J.,’ No. Ixxxvi., p. 96.

+ Iam sure so dispassionate a writer as Dr. Griffin will excuse me for remind-
ing him, that to compare a dry lens with an immersion lens, is not usually
considered a fair proceeding; and that he would have done better to have made
the comparison with Zeiss’ No. 2 immersion (1; inch): not that I expect the
result would have been much different, if the th had been matched against so
unique a glass as Powell and Lealand’s new 2 inch, but it would have been a
fairer course to adopt.

188 On Zeiss’ 35th Immersion. By W. J. Hickie.

the statement has been made in good faith, and the contrariety is
more seeming than real. Magnification is the product of objective,
length of tube, and focal length of eye-piece. Now, Zeiss’ figures
are based on a length of tube of only 6 inches (while the length in
England is about 10 inches), and on a focal length of eye-piece
somewhat more than 2 inches, while our A eye-piece is, I believe,
about 14 inch focal length.

One quality in this glass (designated as C) which attracted my
notice very strongly is its extraordinary resolving power. Its
“rip” of an object is something enormous. And, as regards its
definition, I may here briefly say, that I am perfectly contented
with it; which is saying a good deal; as few are so hard to
satisfy in this respect. This I infer from having observed the (in
my opinion) very moderate performance which has satisfied my
microscopical friends. Indeed, I have often been called upon to
admire what (in my own work) I should call a failure. In this
connection, a very singular remark is put forward by Otto Miller : *
“The resolving power of Zeiss’ objectives is nothing specially
great. On the other hand, their definition is surpassed by none
of the objectives I have examined, and only equalled by few: the
clearness and repose of the picture is a perfect pattern.”

While accepting Miiller’s happily-chosen words “ Klarheit ”
and “ Ruhe,” as exactly conveying my impression of the per-
formance of my own glass (C), under which the object appears, as
I have heard it described, like a sunlit landscape, with all the
details vividly delineated, and the edge of the striz, to the outer-
most margin, as sharp as a knife, I consider the former sentence so
singularly in conflict with fact, that I must confess my inability to
understand it as having been written by him, unless | am at liberty
to suppose that he wanted to see how facts look when turned topsy-
turvy. Here in this country, if anyone were asked to mention the
most noticeable feature in Zeiss’ objectives, he would unhesitatingly
single out precisely this resolving power, as the one that struck him
most. Or may Miiller’s remark find its explanation in the fact,
that he knew only Zeiss’ older issues? He himself adds in his
Preface: “I ought to mention further, that Zeiss’ objectives have
in these latest times [i.e. subsequently to the year 1870] been
considerably improved, in consequence of which the results I have
recorded no longer correspond to the present standard of perform-
ance of Zeiss’ objectives.” I notice also that his list mentions no
higher power of Zeiss’ than his ;'; inch (dry). Some, indeed,
among ourselves profess to have detected in Zeiss’ objectives a
lower scale of definition when compared with those of Hartnack ;
but, as they omit to mention what lenses of each maker were com-
pared, the remark need not detain us. On one occasion I spent

* “Modern Objectives Compared,’ p. 4.

On Zeiss’ 3;th Immersion. By W. J. Hickie. 189

the better part of a long summer's day at Hartnack’s establish-
ment in Potsdam, and that particular superiority in definition was
just what I failed to discover! Chacun a son gout. But it is of
this definition, and its supposed dependence on perfect centering,
that | now wish to speak.

The popular persuasion with regard to definition would seem
to be, that an objective’s ability to bear deep eye-piecing is a sure
proof of good definition ; and, vice versd, that good definition is a
sure proot of its ability to bear deep eye-piecing ; and, that failure
in these respects is a sure proof of bad centering; and this is the
belief of many, of whose opinions I may not speak otherwise than
with respect.

It may be briefly formulated as follows: “ There can be no
more certain test of good definition * than that a glass bear deep
eye-pieves exceedingly well.”

These I believe to be the prevalent views with respect to the
intimate connection between imperfect centering and imperfect
definition; so that it becomes an interesting point to inquire
‘ What are the real effects of bad centering ?”

Let me first give an illustration. I have in my possession one
of Gundlach’s earliest {ths, brought out when he had his reputation
still to make, the definition of which (with a low eye-piece) has
always been greatly admired. Now, according to the above theory,
this glass ought, by virtue of its excellent definition, to bear deep
eye-plecing extremely well; whereas it breaks down utterly even
under the light burden of a C eye-piece. Nor will the logic of
results be bettered, if we say, that the inability of this glass to
bear a C eye-piece is a plain proof that it can have no pretensions
whatever to fine definition; for “ facts are stubborn chiels, and
winna ding.”

If definition were possible only under the condition of abso-
lutely perfect centering, then definition would be something still
unknown to us; for absolute perfection in this respect is a physical
impossibility.

Nageli and Schwendener ¢ have gone into this matter at some
length.

They remark: “ With regard to perfect centering, the highest
that can be attained by the optician in this direction is at best only
an approximation ; and it is especially in the stronger objectives
that he comes farther short of perfection.”

“ According to common opinion, exact centering is the con-
dition of aplanatism; and this is the view taken by Harting and
Mohl ; and yet it is contradicted both by theory and observation.”

* Dr. Branwell expresses himself (‘M. M. J., Ixxxv., p. 43) more cautiously :
“Deep eye-piecing is, above all, the surest test of correction.”
+ ‘Das Mikroskop,’ p. 69.

ee eee

we eee ae a ee oe

190 On Zeiss’ sth Immersion. By W. J. Hickie

“Let us then inquire what will be the effect of a slight
displacement of the combinations, whereby these, though remaining
in the same plane, are pushed aside laterally in any direction.”

The reader will see on pp. 70-74 of the work referred to how
the editors have carried out their demonstration.

They further remark: “ With every increase of displacement a
corresponding marginal portion of the object is effaced, until at
length the entire margin suffers more or less, leaving only a
central portion of the field still retaining its original clearness,
which portion, however, may take any eccentric position.”

Their final summing up is: “ That imperfect centering does,
indeed, exert an injurious effect upon the optical image, but that
this injurious effect limits itself (if we except the case where the
axes of the combinations are not coincident with the axis of the
tube), to the margin of the field, and only reaches the centre when
the defects of centering are abnormally excessive.”

Therefore the effects of imperfect centering are “to limit the
area of definition,” not to materially affect its absolute quality.

But this perfect centering is the product of several factors, and
depends upon the fulfilment of more conditions than one. Granted
that the axes of all the combinations are exactly coincident, there
will still remain the exact coincidence of these with the axis of the
tube,—which may be affected by the form of the tube itself, or even

by the screw of the adapters,—and next, the coincidence of all the ~

above with the axis of the eye-piece employed,—which latter, again,
may be affected by looseness of fit or indifferent workmanship.

It may, indeed, happen that displacement in one direction
is balanced by displacement in another direction; but these are
elements that cannot generally be taken into account. Where the
second defect comes into operation the injurious effects increase

proportionately with the lengthening of the tube. As this defect —

sets the optical axes of the combinations at a slight angle with the
axis of the tube, its immediate result is to introduce “ want of
parallelism,” which is infinitely more destructive of good definition
than imperfect centering. Anyone may demonstrate this to him-
self by looking at an object with a hand-magnifier, and holding the
instrument slightly tilted. It will be noticed that I have omitted
a case of possible occurrence ; that is, where the lenses themselves
are tilted in the setting. This, however, is not what is commonly
included in the popular idea of “bad centering,” but approximates
to “ want of parallelism. What is tested, then, by deep eye-piecing
is “ want of parallelism” plus chromatic and spherical aberration.
Nageli and Schwendener (p. 139) remark, in reference to this, that
“coarse, blurred outlines, and coloured rims, which do not belong
to the object, invariably point to defective correction of chromatic
and spherical aberration ;” and that “defective centering is betrayed

—

On Zeiss’ 35th Immersion. By W. J. Hickie. 191

by the shifting position of the object when the objective is turned
round” (p. 163). This operation, however, as it depends for its
success upon the precision of the brasswork and the accuracy of
the screw of the adapters, is seldom to be relied on. But the
common practice of turning round the eye-piece in the tube is
altogether illusory.

These considerations have suggested to me that possibly, where
a foreign objective is tested on a microscope for which it was not
constructed, and gets suspected of imperfect centering, the blame
may be more justly apportioned between the maker of the micro-
scope and the maker of the adapter. The chances, then, of perfect
centering, as the phrase is popularly understood, are something
infinitesimally small; and the generality of French and German
opticians do not seem to distress themselves to any great extent
about its attainment. Their modus operandi is pretty much as fol-
lows :—The back combinations are fixtures, put together and placed
as fairly as is compatible with a moderate expenditure of labour. The
workman then addresses himself to what he regards as the real
business of the day, that is, to “ marrying lenses,” as he calls it. In
other words, he tries on front after front, taken almost at random
out of a great number, till he hits upon that one which exactly ac-
commodates itself to the previous combinations, these fronts being,
as an optician expressed himself to me, ‘‘made in bushels; yes,
sir ; made in bushels by girls.” I could give, if it were desirable
to do so, a goodly list of French and German opticians who follow
this facile plan of manufacturing “ first-class objectives.” On the
other hand, I could only mention two with any confidence, who, to
judge by their workmanship, appear to follow a better advised
- method, and these two are Zeiss and Seibert. Glasses made on the
first plan are easily recognized. Let the intending purchaser only
hold them up to the light, and he cannot fail to notice the enormous
disproportion between the breadth of the front lens and the breadth
of the hindermost lens. There is, of course, a trick in this. As
spherical abertation turns upon the fact that the focus of the peri-
pheral rays is always shorter * than that of the central rays, which
disparity increases, part passu, with the distance from the axis, t
it is quite conceivable that the adaptation of an extremely minute
front lens to wide back combinations may shorten the labour of
correction very considerably. Such glasses, when used with a low
eye-piece, sometimes exhibit very brilliant definition ; but then it is
only within a certain limited range of the correction-screw. They
will also generally be found, in spite of their good definition, to

* Thus, if we divide the periphery into a number of zones, the rays of the outer
zone will have a shorter focus than those of the next zone, and the rays of the
second zone a shorter focus than those of the third zone. See Nageli, /.c.

t+ Nageli and Schwendener, p. 43.

192 On Zeiss asth Immersion. By W. J. Hickie.

break down under deep eye-pieces, which popular theory says they
ought not to do, and are further characterized by having almost
no working distance, while their real magnification is always vastly
below the nominal amount. :

I propose to give now a tabular statement of the estimated
performance of the three lenses I have mentioned ; namely,
Zeiss’ 3's inch (C), Seibert’s »'¢ inch, and Schieck’s #5 inch. My
manner of procedure has been as follows: I have taken 1000 as
the highest number of marks that could be assigned to any objec-
tive for its performance, and have made my estimate in each case
with this number as the maximum. In some instances I have
given the average of three different trials.

Stauroneis spicula (horizontal).

OpgicTrvES COMPARED. Marks.
Zeiss’ 3. inch Fe Pree Ao no!) | SAY
Seibert’s 3, moh.) ie Ge a
Schiecek’s 2h. inch s,.) hoor soci ae (hoe arash ee ODD

Stauroneis spicula (vertical). °
Zeiss’ 3. inch wed EA eS ak eee
Neibertia.ip inch. a: ad yatly ts ieee 0)
Schiegk's'5 meh ap os, ech - tee fda) Deena 0

Frustulia Saxonica (transverse lines).

Zeiss’ 3. inch ere fre TY

Seilbert’s => Inch 35) 20. pes pct ese heuer ete

Schieck’s' inchs. as oa ee ee

Frustulia Saxonica (longitudinal lines).

Zeiss’ 3; inch oo ee ite nih o.5y = gid ae gee eS

Seiberts 3, neh..." 2.) °:. 0. ska ene

Schieck’s5 imehiis “Lyi" (Ae. 60 ae
Navicula crassinervis A (transverse lines).

Feiss’ Se neh. wie adily ced aie Cee en OE

Seibert's 3, inch. UA a ee

Schieck’s; 2 inchy’ «if »1¢) +4) iive() tag) | cee
Navicula crassinervis B (transverse lines).

Zeiss’ =~ inch PR MELD We ec Ol an 2heid)

Seibert’ gp inch... (> sia) 2. Deb hae Bae Oe

Schieck’s 3, inch... ... 20 ne ae AD)

Two of these were examined, the second somewhat finer than the first.

Amphipleura pellucida (transverse lines).

Zeiss’ - inch weg] coe (Loscee sey lov git tes) (A LO
Reiberts.g 7 ICR 5s al, ses ny ligt) Jip See
Behiedks smn eee le Se So

Lamplight was employed on each occasion.

One word here about testing objectives. I have repeatedly
heard it asserted, that the only proper course to pursue is to try
them all, whatever their number be, under conditions exactly the
same ; that is, on the same object and with precisely the same

eS eae ee

On Zeiss’ y'5th Immersion. By W. J. Hickie. 193

kind of illumination ; and at first sight such a course appears to
recommend itself to the judgment of all. But it will require no
great amount of consideration to convince any reasonable being
that no method could be more unfair or more productive of false
results. Every high power has its own peculiar idiosyncrasy, has
its own particular way in which alone it can be induced to do its
best ; and the illumination which is admirably suited for one glass
may be very unsuitable for another. Or are we to expect all
objectives to do equally well under all possible conditions of illumi-
nation? for that is pretty much what it amounts to, seeing that
almost every microscopist has his own pet mode of illumination.
To take an instance from the objectives in my own possession :
Schieck’s (so-called) 4 inch immersion works best with an
Abraham’s prism, brought up as close as possible to the stage, the
top edge of the prism being half an inch higher than the object,
and set at a particular angle. Zeiss’ y';th (C) is at its best when
the angle formed by a line drawn from the object and one drawn
along the bar of the mirror is exactly two degrees less than a right
angle ; and it shows itself very sensitive to any departure from
this precise arrangement. Seibert’s =;th, again, exhibits its best
performance when the above-mentioned angle is some three degrees
greater than a right angle. My plan therefore has been to find
out under what conditions each lens performs best, and to let each
be tried in its own way, and then to estimate the results: a
troublesome plan, no doubt, but, as I think, the only fair one.

I may now briefly state what I have been able to do with this
C lens.

(1) Resolved Méller’s (so-called) Nitzschia eurvula into dots,
and that too with the greatest prominence.

(2) Resolved every three out of five frustules of Amphipleura
pellucida.
~ (8) Resolved the transverse lines of Stawroneis spicula, with
the frustule lying vertical; that is, with the lines in the same
direction as the illumination.

The first, I dare say, does not amount to much; and the
second, perhaps, is not more than people usually expect from a
first-class objective ; but that there are many glasses able to do
the third, and with the same means, is what I shall believe—when
I see them do it.

I wish also to have it distinctly understood, that by “resolved ”
I do not mean “a wheen o’ skarts” dimly visible through a dirty
mist, but a complete resolution.

In doing the second I employed a silver mirror, with bright
sunlight modified by blue glass. For the first and third I had
merely a Bockett lamp, with a silver mirror assisted by certain
paper shutters.

194 Corrections in the President's Address.

On the evening of the 7th of March I also saw with this lens,
clearly and distinctly, the longitudinal lines of Nav. crassinervis,
for the first time in my life. Did the same again on the 13th.

It will be inferred from the prominent place I, have given to
Stawroneis spicula throughout this trial, that I attach very great
value to it as a test for high powers. And such, indeed, is the
case. Of its extreme flatness, which recommends it for use with
objectives of the very finest and most delicate construction, I need
say little. There are other specialities connected with it. While
a good +'sth may be able to show the strie pretty fairly, a still
better ~;th will reveal still more; and the best glass now in
existence will probably leave something, either in matter or degree,
to be shown by the still better objectives which may be used by
our aftercomers. Or to put it thus: if a person possess half-a-dozen
yeths, such that the second surpass the first, and the third the
second, and so on, each surpassing its predecessor by a specific
degree of excellence, and he try them upon it in the ascending
order, beginning with the lowest, he will hardly, when he has tried
his last and best glass upon it, rise up with the persuasion that he
has completely exhausted his test. ‘To be sure, the same might be
said, in a certain sense, of almost any test, but of none so truly, so
emphatically as of the one here mentioned.

But after all it really does not matter very much what the
particular test is, if the operator only observe these three con-
ditions: (1) that the test employed be one that ought to be just
within the capacity of the class of objective he is trying; (2) that
the operator be sufficiently exacting as to what constitutes the
best possible image ; (3) that he recollect with sufficient keenness
what that best possible image is.

Corrections in the President's Address.

By some unaccountable oversight, in copying out the data for
calculating the number of molecules in liquid water, the factor
expressing the specific gravity of the vapour of water was omitted,
and afterwards overlooked. The number of atoms of a gas should
really be multiplied by $ x 770 x =s x .4°= OFT ear
moreover, on reflecting on the relative reliability of the determi-
nations by the various authors of the number of the atoms in gases,
it appears that in taking the mean, greater weight ought to be
allowed to that by Clerk-Maxwell, since founded on more recent
and accurate data. If his results be considered to be equal in value
to those of Stoney and Thomson combined, the mean would be

SE

Oorrections in the President's Address. 195

reduced to so nearly the same extent as the number of the mole-
cules of liquid water is increased by the above-named correction,
that the numbers given in the Address may be considered to be as
good an approximation to the truth as can be determined in the
present state of the question, and all the general conclusions need
not be in any way modified.

In order to avoid any misunderstanding, it may however be
well to give the corrected numbers, which are as follows:

The contraction of the vapour of water in condensing into a
liquid should be to y's.

The number of atoms and molecules in a cubic roy

should be—

oI
B
ie)
a

1 iviis€2) {22151 se aR IO Oe A 6,000,000,000,000
In liquid water Sse ee we | ee eTOOLOOO 000000000
Tnphorneg S40. Oise OTe ee at 65,000,000,000,000
In living albumen—
Albumen .. es. 17,000,000,000,000
Water in molecular combination .. 923,000,000,000,000

940,000,000,000,000

In a sphere of =, inch diameter—
Albnmen .. = 10,000,000,000,000

Water in molecular combination be 490,000,000,000,000

500,000,000,600,000

In the length of ss¢55 inch there would be about 2000 mole-
cules of water and 500 of albumen, which were the numbers
previously adopted, so that the general conclusions are not at all
modified by the corrections.

VOL, XV. . 1

( 196 )

PROGRESS OF MICROSCOPICAL SCIENCE.

The Development of Hoematococcus lacustris—An account of re-
searches upon this microscopic plant, and upon the foundations of a
natural classification of the Chlorosporous Algz, are just published
by Rostafinski—lately a pupil of De Bary—in the ‘Memoirs of the
Academy of Sciences of Cherbourg,’ * which are thus abstracted by
Professor Asa Gray in ‘Silliman’s American Journal ’:—The identity
of Protococcus, Heematococcus, or Chlamydicoccus nivalis and pluvialis
is made out; at least it is shown that the latter can live upon snow
and ice, and that the development is identical. For the generic name
of the Red-snow plant, &c., Agardh’s name of Hematococcus is
preferred, on good grounds: the specific name adopted is lacustris,
Girod-Chantrans having well investigated the plant and figured and
described it, under the name of Volvo lacustris, so long ago as the
end of the last and the beginning of the present century (1797, 1802).
Hematococcus propagates by two kinds of zoospores ; i. e. sometimes
by large and ordinary ones, resulting from the division of the con-
tents of the cell or plant into four daughter-cells, each of which is
transformed into a zoospore of somewhat complicated structure ;
while other individuals transform their contents into about thirty-two
microzoospores. The development of both kinds of zoospores into
the plant has been observed by Rostafinski. The development is
non-sexual. Velter’s supposed discovery of the copulation of the
large zoospores is discredited and explained away. Rostafinski con-
cludes that Hematococcus is devoid of sexual reproduction. Following
up Decaisne’s early hint that the reproductive organs of Algz should
furnish the characters for their natural arrangement, he indicates the
principal groups or tribes of the Chlorosporee which have thus far
been made out, by De Bary and others, with some reorganization.
Thus, after the Conjugate, in which fecundation takes place by the
conjunction of two immobile cells of the same value (i.e. with no
distinction of male or female), he proposes to place a parallel tribe,
Isosporex, in which there is a copulation of zoospores, the sex of
which is equally indeterminate (Hydrodictyon, Botrydium, &c.).
The third is Oophoresw of De Bary (Spheroplea, Vaucheria, Gidogo-
nium, &c., to which Rostafinski adds Volvyox and Eudorina); here
the fecundation is by antherozoids and oospores. And he is disposed
to take Hematococcus as the type of a fourth tribe, Agamer, pro-
pagating non-sexually by spores.

New Colouring Agents in the Examination of the Tissues—In a
memoir devoted to the subject of amyloid degeneration of the kidney,
liver, and spleen, which appears in a recent part of the ‘Archives de
Physiologie,’ M. Cornil, of La Charité, gives the results of his experi-
ments with several new colouring matters. Two of these, according
to the ‘ Lancet,’ were methyl-anilin violets discovered by M Lauth,
the third was a. violet discovered by M. Hoffmann, of Berlin. The

* Tom. xix., pp. 137-154, 8vo, 1875.

NOTES AND MEMORANDA. 197
.

preparations can be stained with these violets either when fresh or
after being hardened in spirit (Miiller’s fluid or picric acid); and the
colouring agents have this peculiarity, that certain tissues, as cartilage,
decompose them into a violet-red and a blue-violet, each of which
becomes fixed in different elements of the tissue; the hyaline matrix,
for example, assuming a red colour, whilst the nuclei and cellules, as
well as the cartilaginous capsules, become of a blue-violet tint. The
normal tissues of the liver, kidney, and spleen, however, do not de-
compose the violets, but when amyloid degeneration is present, the
degenerated and semi-transparent parts resembling colloid become of
a violet-red, whilst the normal elements are tinted of a violet-blue,
and thus a means equal, if not superior, to that of iodine, is afforded
by which the changes may be followed.

NOTES AND MEMORANDA.

An Improved Method of Numbering Objectives.—The ‘ American
Journal of Microscopy ’—a new venture—states that two methods
have been hitherto in use for numbering objectives—that is to say, for
expressing their focal value. The custom adopted on the continent of
Europe is to use an arbitrary series of letters or numbers, the different
series adopted by various makers having entirely independent values.
In England and in this country, the general practice is to state the
focal value of the objectives in parts of an inch; thus a 1-inch
objective is supposed to be equivalent to a simple lens of one-fourth of
an inch focus. This is a very simple, obvious, and accurate method,
provided the makers adhere strictly to it. But it frequently happens
that a 1th is more nearly a 1th or }th than a jth. A celebrated so-
called ;4,th is in reality more nearly a }th, while a famous },th of a
well-known English firm is rated by our best microscopists as a 51,th.
Mr. George Wale (U.S.A.), whose objectives are deservedly attaining
great favour, has adopted the system of marking his objectives and
eye-pieces with their magnifying power, taken at the standard distance
of ten inches, Thus a 1th is rated at 40 diameters, and a 4th at 120
diameters. ‘Two important advantages result from this. In the first
place, the owner of the microscope is enabled to calculate accurately
the exact magnifying power of every combination of the different
parts of his instrument; and secondly, objectives may in this way be
accurately rated, which is sometimes difficult, or rather inconvenient,
on the other systems. Thus it would be awkward to assign to a lens
magnifying 113 diameters, its exact focal value, but 113 diameters is
not a very unmanageable number.

Best: Cement with Glycerine—Mr. W. H. Walmsley, of Phila-
delphia, writes to ‘Science Gossip’ of February, to say that he has
used glycerine for many years in the mounting of vegetable and insect
preparations, and has very rarely lost a slide from leakage. “I have
used every description of cement with which I am acquainted that

pe 2

198 NOTES AND MEMORANDA.

could be employed with such a medium, and have found the white
zinc cement, when properly prepared, to be by all odds the most
satisfactory, on account of the facility with which it can be used, and
its permanence. I usually keep a supply of cells ready made, with
one or more coats of the cement, according to the thickness of the
specimen to be mounted. A thin coat of the zinc is then to be applied
by means of the tin table, the cell filled with glycerine, and the
object placed therein as usual ; the cover is then applied at one edge
to the ring of cement, and gently loosened until it touches all around
its circumference, when, being slightly pressed, it will be found to
adhere quite firmly. A delicate spring compress is then to be
applied, to prevent possible displacement of the cover, and the whole
slide thoroughly washed in cold water with a brush, to remove every
trace of glycerine. Then remove the compressor, and replace upon
the tin table, and apply a thin coat of the cement to the edge of the
cover, to be repeated until the slide is finished. The same process is
applicable to deep glass cells.”

A Growing Cell adapted for supplying Moist Air.—A cell of this
kind, which promises to be of use in experiments on living fungi, has
just been described :by Drs. Lewis and Cunningham in their recently
published work on the fungus disease of India. It consists of an
ordinary glass slide 3” x 1”, with a ring of beeswax (softened by
the addition of a little oil) pressed on its surface towards the middle. ~
Intervening between the wax and slide—clamped by it—is a narrow
slip of blotting-paper ; and above the wax a thin cover-glass is placed
with a drop of fluid containing the spore or germ to be watched. The
preparation will now be hermetically sealed except at the spot where
the blotting-paper is inserted, the latter serving as an excellent
channel for the air and moisture necessary to the perfect growth of
the object under cultivation. There is no danger of dust being intro-
duced, and the gases which the nutritive fluid may generate can
readily escape.

New Formula Objectives of Seibert—The editor of the ‘ Cin-
cinnati Medical News’ says, in his February number, that “several
months ago we noticed in the ‘ Medical News’ an objective, No. 5
1th) immersion made by Seibert, of Seibert and Krafft, of Germany.
We spoke of it as a fine glass, comparing very favourably with the
work of the best English makes. Quite recently we have received
from the same firm two other objectives, a No. 5 and a No. 6 immer-
sions, made on a new formula, either one of which is very superior to
the No. 5 we before described. We have subjected them to the
severest tests, and have always found their performance admirable.
We do not like to make invidious comparisons, but we will state that
in comparing them with a recent 4th by R. and J. Beck, we in-
variably found their resolving power quite superior, and so markedly
so as to preclude any doubt.”

( 199° 7)

CORRESPONDENCE.

Mr. Wenuam’s Criticism on Proressor Kerra’s DIAGRAM AND
CoMPUTATION.

To the Editor of the ‘ Monthly Microscopical Journal,

ALEXANDRIA, VIRGINIA, January 15, 1876.

Sir,—It seems to me desirable to reply to some of Mr. Wenham’s
remarks * in relation to my computation of the angular aperture of
the Museum ,},th, lest his errors should prevent some from seeing the
full force of the result.

With regard to Mr. Crisp’s ith, it was perfectly immaterial to me
which of the objectives, having the aperture ridiculed by Mr. Wenham,
was taken up. And I am now perfectly willing to take up Mr.
Crisp’s, if anyone desires it, and have no doubt that it would also
illustrate the same statement, viz. “that the so-called theoretical limit”
to the amount of light that can pass out of glass into air, has nothing
whatever te do with the aperture of immersion lenses.

My diagram, which Mr. Wenham dismisses in a sentence quoted
by Mr. Mayall, jun., represents correctly (as stated in the papers
accompanying it) the lenses of the Museum ,),th, an objective which
is not known at the Museum to have been surpassed by any other of
the same power. Mr. Wenham’s guess, that it could not be focussed
upon a dry object, is directly contrary to Dr. Woodward’s statement
in his accompanying paper,f viz. “it performs admirably as a dry
lens.” The diagram further represents the path of a ray of light,
which is of course “drawn in accordance with the computed results.”
Tt however fails to satisfy Mr. Wenham for the very curious reason
that it “suits the proposition,” whatever that may mean. The result of
the computation is sufficient evidence that the curves, distances, and
refractive indices were correctly given by the maker, otherwise, the
objective could not have been found free from spherical aberra-
tion. But in addition to this the lenses were unscrewed by Dr.
Woodward and myself and the maker’s elements verified by measure-
ment, as far as it was possible to do so, before the computation was
undertaken.

The fact that the diagram represents correctly the well-known
Museum ,},th, the photographs taken by which have given such
general satisfaction, adds interest to the paper. But if elements had
been guessed out, free from spherical aberration, the force of the result
would have been the same.

Mr. Wenham’s attempt to fix the limit of mathematical computa-
tion is quite as amusing as his attempt to fix the limit of aperture. I
can assure him that it is perfectly possible to compute the spherical
aberration of any combination of lenses however complicated and with

* *M. M. J.,’ Nov. 1874, p. 221. + ‘M.M.J., Sept. 1874, p. 127,

200 CORRESPONDENCE.

any degree of accuracy, and not only possible but not difficult. Mr.
Wenham’s remark is the more amusing in that it comes from one
who professes to measure on paper the variation due to chromatic
dispersion !

Respectfully, &e.,

R. Kerrs.

Notes on Pror. Rupert Jones’ Memoir oN THE VARIABILITY
or FoRAMINIFERA.

To the Editor of the ‘ Monthly Microscopical Journal.’
YorKTOWN, SuRReEY, February 23, 1876.

Dear Srr,—Permit me to point out a few corrigenda in my paper
“On the Variability of Foraminifera,” in the ‘Monthly Microscopical
Journal’ for February, No. lxxxvi., p. 61, &e.

1. My friend, Mr. H. B. Brady, whose works are quoted in the
memoir, reminds me that, with regard to Squamulina, described by
Schultze as calcareous and pore-less, and arranged in the Table, at
p. 89, as a “porcellanous” form, Mr. H. J. Carter has referred two
‘“‘arenaceous” species to this genus; one monothalamous or sub-
multilocular, the other polythalamous. See his memoir “On Two
New Species of the Foraminiferous Genus Squamulina,” &c.*

2. Mr. Brady also assures me that the quadriserial arrangement of
the chambers’in Tetratawis (Table, p. 89) is not sufficient to distin-
guish it from Valvulina. He can only say that in the Carboniferous
strata there are more quadriserial than triserial Valvuline, and vice
versd in the Tertiary deposits and recent seas.

3. He adds that Ellipsoidina (see the Table, p. 90) has its nearest
ally in Chilostomella, and both should closely follow Polymorphina,
though almost as much related to Bulimina ; and that Allomorphina
goes with the first two in Reuss’s group of the “* Cryptostegia.”

4, Archeospherina (in Table, p. 92) is now regarded by Dr. Daw-
son as being probably separated germ-like portions of the acervuline
variety of Hozoén. fT

5. Errata et Addenda. Page 62, line 34, for 18 read 20.

P. 65, first footnote, add Dr. Wallich also has figured a similar
Planorbulina (?) with symmetrically perforated chamber-walls, in
‘The North-Atlantic Sea-bed,’ 1862, pl. 6, f. 20; and in his memoir
entitled ‘Deep-sea Researches on the Biology of Globigerina, 1876,
fig. 20.

P. 73, last line, for procure read produce.

P. 87, third line from bottom, for 2-6 read 2-5.

P. 88, line 8, for 7 read 6.

P. 89, line 32, for Gryroporella read Gyroporella.

Pp. 90 and 91, Ataxophragmium and Plecanium occur twice over
on account of the double character (both sandy and smooth) of the
types to which they belong.

* “Ann. Mag. Nat. Hist.,’ ser. 4, vol. v., pp. 309-326, pl. 4 and 5.
+ See ‘Quart, Journ. Geol, Soc.,’ yol. xxxil., p. 73.

oa ety A il

CORRESPONDENCE. 201

Lastly, observing that varieties among Foraminifera are of equal
value to species and even genera in higher animals, as far as concerns
bathymetrical and geographical distribution, I would refer the reader
to Dr. Carpenter’s “ Researches on the Foraminifera,’ ‘ Phil. Trans.’
for 1860, p. 584, &c., for valuable remarks on the Variability and
Persistence of Foraminifera. See also Lyell’s ‘ Antiquity of Man,’
4th edit., p. 494, &e.

I am yours truly,

T. Rupert JONES.

P.S.—With regard to the spicular contents of Carpenteria and
Polytrema, mentioned at p. 65 (fifth line), Mr. H. J. Carter has
convinced himself by extended and close observation that the Sponge
spicules found in these Foraminifera have been chiefly taken in by the
sarcode during life, together with diatoms and other organic par-
ticles. In some instances the broken walls have allowed the entrance
of such strange bodies into the cavities; and sometimes parasitic
Sponges wholly or partially invest the shells. Occasionally the
spicules are incorporated in the wall-tissue. Lastly, Mr. Carter
recognizes a close similarity in structure and features between Car-
penteria and Polytrema, leading him to combine the two under the
latter (older) name. See his memoir “On the Polytremata,” &c.,
‘Ann. Mag.N. H., ser. 4, vol. xvii., March 1876, p. 185, &e., pl. 13.
—T. R. J., March 11, 1876.

CHROMATIC AND SPHERICAL ABERRATION.
To the Editor of the ‘ Monthly Microscopical Journal.’

16, Firzroy Square, W., March 10, 1876.

Smr,—In p. 232 of your November issue, Dr. Royston-Pigott
states that the spherical aberration of a monochromatic ray “is for
convenience called chromatic aberration,’ of which I maintain a
monochromatic ray to be destitute.

In p. 129 of your last issue he admits that “in standard works on
Optics, chromatic aberration and spherical are treated for convenience
as distinct things.” When we are in possession of Dr. Royston-Pigott’s
“standard work on Optics,” in which, I presume, these optical condi-
tions will be treated as identical, we shall be enabled to form an
opinion on the relative convenience of these very opposite modes of
treating the subject.

In your February number he expresses a hope that I and others
who have addressed to you our dissent from his opinions, will on
further reflection regret having done so. I can only assure him that
I do not, nor am I likely to, regret this or any other steps that I
may have taken in furtherance of the logical accuracy of scientific
nomenclature.

I remain yours faithfully,

Cuas. Brooxe.

202 CORRESPONDENCE.

CHROMATIC AND SPHERICAL ABERRATION.
To the Editor of the ‘ Monthly Microscopical Journal,’

CHISLEHURST, March 15, 1876.

Sir,— May I, as a very old member of the Microscopical Society,
be permitted a few remarks on the two papers by Dr. Royston-Pigott
which appeared in the ‘M.M.J., No. Ixxxiii., p. 232, and No. lxxxvii.,
p. 128, which in my opinion are highly pernicious, as being calculated
to produce in the minds of the uninformed a hopeless confusion of ideas
between two things utterly distinct, and which the author himself
incidentally shows to be distinct in the course of his illustrations.

I would premise, that in mathematical attainments I do not
presume for one moment to compare myself with this gentleman ; but
as a veteran worker with the microscope, who believes that an inti-
mate acquaintance with the theoretical and practical construction of
all the optical parts of the instrument is a necessity to an accurate
observer, I have for over five-and-thirty years studied the science of
optics with a special view to its practical application; and I trust
that I may, without offence, express my strong dissent from the con-
clusions at which Dr. Royston-Pigott appears to have arrived, and to
express my conviction that, from some unexplained cause, he applies
another meaning to the term “chromatic aberration” than that gene-
rally accepted.

At p. 181, No. Ixxxvii., of the ‘M. M. J.,’ some well-known experi-
ments illustrative of chromatic and spherical aberrations are described ;
but oddly enough, instead of pointing out that the differing positions
of the foci of the red and violet images of the sun, as formed by the
marginal rays only, or by the central rays only, illustrate the
chromatic aberration, and nothing else, the author dilates upon the fact,
that the different positions of the foci for the red image of the sun
when formed by the marginal or central part of the lens respectively,
and the same with the violet image, show, that both the red and
violet rays are subject to spherical aberration ; and the foot-note in
p- 182 of the same number is to the same effect.

But this is a fact about which, so far as I know, there has never
been any dispute. Of course the rays of light of all colours are
subject to spherical aberration when transmitted through lenses with
spherical surfaces ; but that has nothing whatever to do.with chromatic
aberration, which arises solely from the various degrees of refrangi-
bility of the differently coloured rays. In point of fact, chromatic
aberration is due to the compound character of the light employed,
and has no existence with homogeneous light; while spherical aberra-
tion is due only to the form of the lens employed, whether the light is
simple or compound ; and these facts are abundantly demonstrated by
the experiments detailed by Dr. Royston-Pigott himself.

“ Chromatic aberration” requires for its correction the use of at
least two refracting media (besides the air) of varying dispersive
powers, and cannot exist with monochromatic light. “ Spherical
aberration” can be corrected or balanced for monochromatic light

PROCEEDINGS OF SOCIETIES. 203

with two lenses of the same refracting medium, by combining a bi-
convex and a meniscus lens, as shown by Herschel.

Lastly, a reflecting telescope has its principal reflector worked to
a parabolic curve,.to avoid the spherical aberration that would be
introduced were the reflecting surface spherical ; but though compound
light is used, there is no chromatic aberration to correct, whether the
reflecting surface is spherical or parabolic in its curve. How then
these two errors can be regarded as “ identical in character,” is to me
simply incomprehensible.

Dr. Royston-Pigott complains, and with reason, of the scant
courtesy of tone in some of the correspondence which has appeared in
this Journal upon optical questions ; but surely he should not include
in his condemnation the letter of our old friend Mr. Chas. Brooke
which appeared in No. lxxxy., p. 45, in which I can perceive nothing
but a temperate and legitimate protest against what the writer regards
as erroneous doctrine upon a scientific matter.

I shall be very sorry if Dr. Royston-Pigott regards my letter in
the same light, as nothing can be farther from my thoughts than
offering him any offence; but unless adverse criticism of novel
theories can be freely indulged, scientific progress must be impeded.

I am, Sir, your obedient servant,
Gro, SHADBOLT.

PROCEEDINGS OF SOCIETIES.

Royat MicroscopicaL Socrety.

Kine’s CoLiece, March 1, 1876.

H. C. Sorby, Esq., President, in the chair.

The minutes of the preceding meeting were read and confirmed.

A list of donations to the Society was read by the Secretary, and
the thanks of the meeting were voted to the donors.

The Secretary said they had received a paper “ On the Measurements
of the Diatoms of Méller’s Probe-Platten,” by Professor Morley, which
would be printed in the Journal. The paper was accompanied by
a number of tables, copies of which had also been sent for distribution
amongst the Fellows present.

Mr. W. N. Hartley, F.C.S., read a paper “On the Identification of
Liquid Carbonic Acid in- Mineral Cavities,” illustrating the subject
by drawings upon the slate, and by specimens exhibited under the
microscopes in the room. Two specimens were so arranged that a jet
of hot air could be impinged upon them whilst under observation, and
the sudden vaporization and subsequent condensation of the liquid
enclosed in the cavities was in this manner clearly demonstrated. An
ingenious contrivance was also exhibited by means of which the
critical point of a liquid could be readily determined.

The President felt sure that the Fellows would give a very hearty
vote of thanks to Mr. Hartley for the very interesting paper which he
had just read to them. He was very much gratified to find that

204 PROCEEDINGS OF SOCIETIES.

Mr. Butler’s experiments led up to the same results as those which
had been arrived at by Mr. Hartley. At the time his own experi-
ments were made, it was not known that liquid carbonic acid occupied
any place in the mineral world ; but from the conclusive observations
which had been made since that date, they could not now doubt its
existence there as a natural product. Mr. Hartley had enjoyed the
advantage of the experiments of Professor Andrews upon the subject,
which of course he (the President) had not the opportunity of referring
to at the time his own experiments were made. At the present time
an observer knew exactly what to look for, and they knew very well
how much more easy it was to find a thing when we knew just
exactly what it was that we ought to look for. Some of the effects
which had been mentioned by Mr. Hartley were very remarkable; the
peculiar effect at the time of boiling was very so, but then it was
so quickly done and the changes took place so rapidly that it was
quite a matter of astonishment to anyone seeing the experiment for
the first time. In sapphires he could never detect any water in the
cavities ; they appeared in all cases to be filled purely with carbonic
acid ; and he believed that it was a fact that the sapphire was always
found in connection with limestone. Any gentleman who had not yet
seen these effects would be very much surprised at them. In their
bearing upon theoretical geology they were of course of very great
importance. :

Mr. Hartley said he had observed in the case of nearly all
his specimens that the surface of the fluid in the cavities had a
concave curvature, showing that the sides were wet, and thus in-
dicating the presence of water as well as carbonic acid; but in the
specimens of sapphire the curvature of the surface of the contained
fluid was convex, and the sides seemed to be perfectly dry, from which
he judged that the fluid in these instances was pure carbonic acid.

The President said that it gave him much pleasure to announce
that Mr. Butler had kindly promised to exhibit his specimens at their
approaching conversazione. Mr. Hartley also signified his willingness
to exhibit his apparatus, &c., on that occasion.

Mr. Rutley mentioned that the President had referred to the
circumstance of the sapphire being usually found in limestone ; there
was, however, an instance occurring in some mines in Carolina, U.S.A.,
in which corundum occurred in gneissic rock.

The President said that the cavities were very rare in the case of
the ruby ; Mr. Butler had only found one or two specimens containing
liquid, out of many hundreds which he had examined.

The Secretary said they had received a paper from Mr. Dallinger,
one of their Vice-Presidents, “Ona New Arrangement for I]luminating
and Centering with High Powers.” The paper was too technical to
be readily understood unless it were in the hands of every Fellow.
Mr. Dallinger had found that the precise position of the lamp was of -
great importance as well as the exact centering of the illuminating
apparatus, and he had devised a lamp for the purpose with a screw
motion, by means of which the exact position required could be
obtained. The paper without the diagrams would, he feared, be quite
unintelligible to the meeting; it would therefore be “taken as read,”

PROCEEDINGS OF SOCIETIES. 205

and would be printed in the next number of the Journal, together with
the illustrations.

The thanks of the Society were unanimously voted to Mr. Dallinger
for his communication.

Mr. F. Rutley read a paper “On the Structure of certain Rocks—
Obsidian and Leucite, with Notes on the Spheroidal Structure of
Perlite.’ The paper was illustrated by a number of coloured
diagrams and by specimens exhibited in the room.

The President felt sure it would be the pleasure of the Fellows to
return their best thanks to Mr. Rutley for his paper, for papers of this
kind were extremely rare, and were of great interest and value.
Miecroscopists who did not know the wonderful things to be found in
rocks, would be greatly astonished at what was to be seen there, if they
would take up the examination as a study. Even in slags which had
without any question been melted, they might find things which they
would be sure to say at first sight were organic, and when they came
to the study of the minute crystals found in some of these rocks,
it was surprising to find how very little there appeared to be of
the ordinary character of crystals about them. They would often
meet with structures which were extremely curious, and suggested
many of the ideas which they usually connected with living bodies.
He mentioned this as showing that they should be very cautious
in coming to conclusions upon mere resemblances. He quite agreed
with Mr. Rutley that the structure of the cavities was very re-
markable. He had not examined the Perlites, but fully agreed with
Mr. Rutley that the facts were exceedingly curious, and that they
represented on a small scale what went on in nature ona large one.

The Rey. T. W. Freckelton was introduced by the Secretary as a
new Fellow, and formally admitted by the President.

The President reminded the Fellows of the Society that the
conversazione to which reference had been made at the previous
meeting would be held on the 21st of April, and asked that all would
assist in bringing objects of interest on that occasion. The Council
had formed themselves into a committee to carry out the arrangements,
and they were very anxious to bring together a good collection of
objects of real interest.

The proceedings then terminated, the meeting standing adjourned
to April.

Donations to the Library since February 2, 1876:

From
Iisa CANCE Nee hoe Vesa meMncne sacle SE nGi Fae Naan eee radar
RiOnceUTisee WV CELL yee a oe Leas) asa el oe eels 1 eta Ditto.
Society of Arts J ournal.. ou Deed sac) ese eOCKaeI
Quarterly Journal of the Geological Society. “No. 125 oc Ditto.
Journal of the Linnean Society a Wn oes Fase Ditto.
The Cincinnati Medical News.
Bulletin de la Société Botanique de France. Two parts .. Ditto.

El Microscopio en Litologia. Par Don Francisco Q.G. Rodriguez Author.
Dioptrica Nova: a Treatise of Dioptricks. In two parts.
By William Molyneux, Esq., F.R.S... .. .. .. -. B.D. Jackson, Esq.

Dr. Thomas Partridge was elected a Fellow of the Society.

Water W. REEVES,
Assist.-Secretary.

206 PROCEEDINGS OF SOCIETIES.

QuEeKett MicroscoricaL CLUB.

Ordinary Meeting, December 17, 1875.—Dr. Matthews, F.R.M.S.,
President, in the chair.

Mr. Ingpen gave a description of the various methods employed
from time to time for measuring the angular apertures of objectives.
Commencing with that of Mr. Lister, which was the only one in
general use prior to 1854, he gave a detailed account of the improve-
ments effected by Mr. Wenham, Mr. Gillett, Dr. Robinson, and others;
and concluded with some remarks upon angular aperture generally,
with reference to the various opinions held upon this somewhat vexed
subject.

Ordinary Meeting, January 28, 1876.—Dr. Matthews, F.R.M.S.,
President, in the chair.

Mr. Ingpen described a portable binocular microscope recently
constructed by Mr. Swift. This instrument not only packed in an
extremely small space, but also comprised. several contrivances of
great convenience. The binocular body, when not in use, could be
turned in front, so as to be quite out of the way. The rack was of
sufficient range for the lowest powers. The stage was extremely thin,
and had a countersunk rotating ring, into which an extra selenite or
mica film could be introduced, or it could be used for the examina-
tion of diatoms, &c., by oblique light. The compound achromatic
condenser was focussed by means of a diagonal slot instead of rack-
work ; and the analysing prism moved in a slot above the binocular
prism, and was thus always ready for use. These and sundry other
arrangements made the instrument very complete and effective as well
as extremely portable.

Mr. T. Curties read a paper by Mr. Henry Davis, F.R.M.S., “On
a Larval Cirripede,” a specimen. of which was found by him on a
feather of a sea bird shot about 500 miles N.W. of the Cape of Good
Hope. It was at first supposed to be the egg of a parasite, but closer
examination proved it to be a crustacean, an advanced larval form of
Lepas pectinata. The paper contained a minute description, and
details of the development of this interesting Cirripede, and was
illustrated by drawings and specimens.

Mr. A. Hammond read a paper “On a Comparison of the Meta-
morphoses of the Crane-fly and the Blow-fly,” in which he endeavoured
to show that the former insect forms an exception to the rule enun-
ciated by Dr. Weismann, wherein he expresses his belief that “in all
those insects in which the anterior larval segments are unprovided
with appendages (legs) the head and thorax of the imago are entirely
re-developed.” Mr. Hammond stated his belief that in this insect the
imaginal disks, if such they were entitled to be called, were to be
regarded rather as invaginations of the newly forming pupa skin than
as independent centres of growth, commencing in separate closed cap-
sules. He described eight pairs of these disks as occurring in the
crane-fly, and particularly adverted to the superior pro-thoracic disks
as being concerned in the formation of corresponding appendages,

.
ty

ll

PROCEEDINGS OF SOCIETIES. 207

whose development, though arrested in the imago, was very con-
spicuous in the preceding pupal stage; and from thence passed to the
corresponding disks and appendages in the blow-fly, to the observa-
tion of which he had been led by the study of the former insect. The
disks in question, which Mr. Lowne had somewhat doubtfully located
in front of the supra-cesophageal ganglia, were described as surround-
ing the anterior terminations of the trachez of the larva. After some
allusion to the apparently anomalous situation of the posterior leg
disks of the blow-fly, as being attached to the trachez instead of the

- nerve centres, as is the case with the anterior and intermediate legs,

Mr. Hammond concluded by contrasting the mode of development of
the tissues in the two insects; calling attention to the complete and
sudden character of the changes in the blow-fly, as compared with the
more gradual processes followed in the development of the crane-fly.

Souta Lonpon MicroscopicaL AND Naturat History Cuvup.

An ordinary meeting of this club was held on October 19, 1875,
at the Angell Town Institution, Brixton. Charles Stewart, Esq.,
M.R.C.S., F.L.S., presided.

An address was delivered by Mr. James Reeves, on “Oysters.”
The lecturer commenced by describing the oyster-beds, and then gave
an account of the spawn of oysters. Tracing the growth of the young
oyster from its birth, when it is lively and swims about the surface of
the water, to the time when, as it becomes heavier, it sinks to the
bottom of the sea, Mr. Reeves gave a long account of the various
enemies of the oyster; the sea-anemone, the “borer,” the dog-whelk,
and the star-fish, attacking the oyster in turn. The various kinds of
oysters were then described; “Natives,” “Channel” oysters, “Jersey”
oysters, and many other varieties. The Report of the Commissioners
appointed to inquire into the oyster fisheries was then criticised, and
the theory that oysters were rendered scarce by over-dredging was
confuted. The important points—how to catch, how to keep, how to
open, and how to eat oysters—were then considered; and various
specimens of oysters were exhibited in illustration of the last two

oints.
A discussion ensued, in which Messrs. Stewart, Hovenden, and
Reeves took part.

At the ordinary meeting held on November 16, a paper was

-read by Mr. G. F. Linney, of Croydon, on “Conchology.” After

describing the method of prosecuting the search for shells, and the
necessary equipments, Mr. Linney gave an account of the method of
killing the animals, cleansing the specimens, storing them, and arrang-
ing them for exhibition. The classification of the Mollusca was next
considered, and the various families of the classes Conchifera and
Gasteropoda described in detail. Mr. Linney then gave various in-
stances of the peculiar localization of certain shells, and of the effect
of heat, weather, &c., upon their growth. In conclusion, the micro-
scopical examination of some of the animals was described, their

208 PROCEEDINGS OF SOCIETIES.

digestion and respiration being easily observed; and the Zonites
nitidulus was mentioned as an especially good specimen.

An interesting discussion followed the reading of this paper, and
the President then gave an account of the reproduction and develop-
ment of snails.

A meeting of the club was held on December 21, which was some-
what special, ladies being admitted, and a large number of microscopes
exhibited. An address was delivered by William Carruthers, Esq.,
F.RS., F.L.S., F.G.S., on “ The Earliest Fruit Remains of the Earth.”
The lecturer restricted his remarks to the vegetation of the Palzozoic
or primary rocks, and described in detail the gymnospermous plants
found in these rocks, and also the coniferous trunks found in sand-
stone beds near Edinburgh, a specimen of which, 4 feet in diameter,
and 40 feet in length, is preserved at the British Museum. Fruits
found in the quartzose rocks at St. Etienne, near Paris, were also
described; these belong to the Taxineous group of trees, and are
allied to the fruit of the Salisburia adiantumfolium—a tree common in
London, but a native of Japan. Passing now to the consideration of
the eryptogamous plants found in the coal-measures, Mr. Carruthers
described the cones which are the fruit of a tree called Lepidodendron,
and compared them, by the aid of diagrams, with the Lycopodium and
Selaginella of the present day. Other fossil cones were compared with
the Equisetum, or horse-tails, to which they are allied in structure.
The ferns found in the coal-measures were then described, and Mr.
Carruthers alluded to his discovery of a specimen exhibiting the
peculiar structure of the fruit. The fossil ferns were compared with
the modern Polypody and the Tunbridge filmy fern. In conclusion,
the lecturer gave an account of a fern found by Professor Edward
Forbes in the Devonian rocks of Ireland, which agrees exactly with
living ferns.

The address of Mr. Carruthers was throughout listened to with the
closest attention; and at its close the audience displayed great interest
in the various objects illustrative of the subject, which were arranged
systematically and exhibited under the microscopes of the members.

The Monthly Microscopical Journal, May 1.1876. Pl. CXXXV

A | | B
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THE

MONTHLY MICROSCOPICAL JOURNAL.

MAY 1, 1876.

I.—Note on the Markings of Navicula Rhomboides.
By Dr. J. J. Woopwarp, U. 8. Army.
(Read before the Roya Microscoricat Society, April 5, 1876.)
Puates CXXXV, anp CXXXVI.

Mr. Hioxte’s reply to my “ Note on the Markings of Frustulia
Saxonica” * was unfortunately crowded out of the February num-
ber of the Journal, and I will therefore postpone any discussion of
the views I am informed he has expressed until I see his paper. I
have, however, received through the politeness of Mr. John Mayall,
jun., copies of Herr Seibert’s photographs, which Mr. Hickie
exhibited as photographs of Frustulia Saxonica at the meeting of
the Royal Microscopical Society, January 5, 1876, and I desire to
offer a few remarks with regard to them.

In the first place, I must compliment Herr Seibert on his suc-
cess in photographing what he saw; and his willingness to exhibit
the photographs is a proof of his sincerity. Next, I desire to point
out the convenience and accuracy of photography for the purpose
of such a discussion as this. Without it I should have been unable
to form any definite opinion as to what Herr Seibert had seen.
Lastly, I must express my conviction that the remark attributed to
Mr. Mayall in the report of the proceedings of the meeting men-
tioned,t that the diatom photographed by Herr Seibert was “a
coarse form of Khomboides,” is quite correct.

This conviction is forced upon me by a consideration of the dis-
tance of the striz apart, in connection with the size and shape of
the diatom as shown in Herr Seibert’s photographs. These make
the diatom four inches long. The length of Frustulia Saxonica
varies from -0012 to °0030 of an inch. (On a slide labelled
Frustulia Saxonica, loaned by Mr. Hickie to Mr. Mayall as
authentic—to which I assented—and loaned by Mr. Mayall to me,
I found none any longer than ‘003 of an inch.) If, then, Herr
Seibert’ has photographed even the coarsest of these forms, his
pictures are taken with over thirteen hundred and thirty diameters.
But his photcgraph of the transverse markings gives 110 lines to

* Monthly Microseopical Journal,’ Dec. 1875, p. 274.
+ Ibid., Feb. 1876, p. 103,
WOOL.) XV. Q

210 Transactions of the Royal Microscopical Society.

the inch. The original diatom then must have had over 146 trans-
verse strie to the y¢o> of an English inch, and it is not reflecting
on their skill as microscopists to assert that neither Herr Seibert
nor Mr. Hickie could have even glimpsed striz so fine as this, for
the objectives which would enable anyone to do so have yet to be
constructed.

It is quite evident, then, that Herr Seibert must have photo-
graphed some diatom much larger than Frustulia Saxonica, and
that this larger diatom was a coarse specimen of Navicula Rhom-
boides, I hope to convince those who will examine the accompany-
ing photographs marked A and B [or their representations in the
accompanying Plates].

On the Moller’s type-plate (specially arranged) belonging to
the Army Medical Museum, there is a specimen of Navicula Rhom-
boides -0069 of an inch long, with 60 “transverse striz ” (really
rows of beads) to the ty's5o of an inch. When this is photographed
so as to give an image of the same size as the diatom photographed
by Herr Seibert, it appears so similar to it in form, and, when the
light is suitably managed, in the character and fineness of the
strie, as to leave no reasonable doubt that it is of the same species
and very nearly of the same size.

In order to approximate as closely as possible to the conditions
indicated by Herr Seibert’s photographs, I used an immersion
No. 9 of Hartnack, and throwing the light lengthwise to the
frustule, obtained the photograph marked A, showing the transverse
strie. I intended to make my picture of the frustule the same size
as Herr Seibert’s ; and, in fact, on my negative it is the same size,
as on the print from his in my possession; but as prints spread
more or less when rolled, and shrink sometimes when not rolled, of
course the frustule on my negative is not precisely of the same size
as on his, though it must be very nearly so. My negative proved
to be magnified 580 diameters, and the striz counted 103 to the
inch on the negative—(on the paper prints they vary of course).
Next, throwing the light transversely to the length of the scale
I obtained the photograph marked B, which shows the longitudinal
lines quite like those in Herr Seibert’s second picture.

I think no candid observer who compares these pictures with
Herr Seibert’s, will hesitate to admit that the two diatoms repre-
sented are very similar frustules of the same species. The small
difference in the number of strie might have been somewhat
reduced had I been able to make the diatom in my pictures of
exactly the same size as that in Herr Seibert’s; and the resem-
blance would have been still further increased if I had stopped out
the background with some opaque paint, as he has done. Instead,
I preferred to stop it out with tissue paper, which, while giving
prominence to the central diatom, permits all the other objects in

Markings of Navicula Rhomboides. By Dr. Woodward. 211

the field to print. Among these objects are several other diatoms,
of which the one indicated with a cross (thus x ) is described by
Moller, in the catalogue accompanying the Museum plate, as
“ Navicula crassinervis” ; in its size, the character of its markings,
and all essential points, it resembles the specimens of Prustulia
Saxonica, which are represented as seen with a higher power in
the photographs accompanying my former paper. A comparison of
these pictures with those is therefore respectfully solicited.

Thus far to convince those who examine these pictures that I
have really before me substantially what Herr Seibert’s pictures
represent. But I have next to observe that, even with the Conti-
nental lenses which I suppose that gentleman to have used, he
ought to have been able both to see and to photograph the hemi-
spherical heads which are the true markings of this diatom. I
retract the error into which I fell when, misled by the imperfect
descriptions of Mr. Hickie, I supposed the longitudinal lines photo-
graphed by Herr Seibert to be diffraction phenomena. They are
merely the result of imperfect definition. I send herewith a photo-
graph of the same frustule, marked C, magnified 870 diameters by
the same Hartnack immersion 9. I have simply increased the
distance from the object to the screen to gain the increased power,
and taken a little more care with the adjustments than in the
former picture. ‘The true markings are, however, much more bril-
hantly shown by a good English or American immersion objective.
I send herewith a photograph (marked D) of a part of the same
frustule, magnified 1550 diam. by Powell and Lealand’s immer-
sion ysth, without eye-piece ; and another (marked E) of the same,
magnified 2700 diameters by the same objective with eye-piece,
which may serve to demonstrate the truth of this statement.

In conclusion, I may remark that while Mr. Hickie argues that
there are valid distinctions between I’. Saxonica and N. cras-
sinervis, several gentlemen with whom I am acquainted go to the
other extreme, and hold not only that there are none between these
two, but even that there is none between them and Navicula Rhom-
boides. I prefer not to discuss either of these points at present ;
but may, perhaps, do so after I have read Mr. Hickie’s paper.

212 Transactions of the Royal Microscopical Society.

II1.—Some Results of a Microscopical Study of the Belgian
Plutome Rocks. By A. Renarp, 8.J.

(Read before the Roya Microscoricau Society, April 5, 1876.)
Puate CXXXVII.

Tis paper is a very brief and comprehensive statement of a few
of the results obtained by applying the microscope to the study
of some Belgian rocks; they are developed more at length in
the Mémoire which I made together with the Prof. de la Vallée
Poussin.*

The most important of the Belgian plutonic rocks is the quartzi-
ferous diorite, found at Lessines and Quenast in the Silurian layers
of Brabant. Delesse, who has made a chemical study of it, con-
sidered the base of that rock as a residue from crystallization, 1. e.
as a silicate whose variable elements are silicic acid, and all the
bases which are found in the various minerals porphyrically de-
veloped in this rock. This eminent lithologist extended therefore
to the rock in question his opinion concerning the constitution of
the base of porphyries in general. But the microscope enables us
to see that in the rock of Lessines and Quenast the base is com-
posed of grains of quartz and feldspar forming a micro-granitoid
agglomeration. As for the oligoclase which, together with quartz
and more or less altered hornblende, makes up the essential elements
of this rock, it presents a structure already observed in the plagio-
clases of trachytes and andesites. This structure is remarked in
lines which are parallel to the outlines of the crystals. With
ordinary light, these lines are of a feeble brownish colour; their

EXPLANATION OF PLATE CXXXVII.

Fic. 1—Oligoclase in the diorite of Quenast, showing a concentric structure.
Polarized light. x 40.

2.—Epidote and calespar, Quenast, x 40.

3.—Liquid cavities containing crystals of Na Cl enclosed in quartz, Quenast.
The prismatic crystals are tourmaline. x 450.

4.—Crystal of labrador fractured and bent by fluidal structure in gabbro,
Hozémont, x 40.

5.—Diallage in gabbro, Hozémont, showing the cleavages of that mineral,
x 28,

6.—Diallage surrounded by fibrous hornblende, x 40.

,, 7 and 8.—Ilmenite, covered in some parts by its characteristic white coating,
in gabbro of Hozémont, x 25.

9.—Fragments of crystals of plagioclase and quartz, surrounded by Sericite
in the elastic Porphyroid of Pitet. Polarized light. x 120.

* “Mem. sur les Caracteres Minéralogiques et Stratigraphiques des Roches dites
Plutoniennes de la Belgique et de l’Ardenne Frangaise,” par Ch. de la Vallee
Poussin et A. Rénard, §.J., t. xl. des ‘Mém. Couronnés de l’Académie de Belgique.’
This work, which is now in the Press, will soon appear.

W.West & C2 Lith.

Microscopical Study of the Belgian Rocks. By A. Rénard. 213

angles are not perfectly sharp ; and, what is very remarkable, the
lines which lie perpendicular to the polysynthetic lamelle run
clear through, without any break at the point where they intersect
the strie (Fig. 1).

In this diorit the microscope has enabled us to prove the pre-
sence of orthoklas, a result to which we have been led by the phe-
nomena of polarized light, just as is observed in the twin crystals of
Carlsbad. We need not stop to describe the microscopic details of
the hornblende, which is generally much altered and often sur-
rounded by an opaque zone in a state of decomposition, which has
also obliterated the cleavages. This mineral often contains apatite,
and this we consider to have been formed simultaneously with the
hornblende; it is also intimately associated with chlorite, ilmenite,
magnetic iron, biotite, epidote (Fig. 2), calespar, and quartz;
minerals which we believe to have been formed for the most part
by the decomposition of the hornblende. Notwithstanding its
state of decomposition, the sections of this mineral are still
dichroic. We have also found in this rock uralite, augite, and
diallage; and by means of the microscope we have proved the
presence of crystals of apatite and ilmenite. ‘These two minerals,
which play an important part in the Belgian plutonic rocks, are
always of microscopical dimensions, and had not been remarked
in that country before we examined them under the microscope.

The microscopic study of the quartz of this rock is of the
greatest interest, since it allows us to determine to a certain point
the conditions in which this diorit was formed. Mineralogists
have long been engaged in the study of the numerous minerals con-
tained in quartz, and of the liquids enclosed in the cavities of this
mineral; but it is especially Sorby, who by opening the way to a
new method in petrography, has shown the geological importance
of these phenomena. Following his example, and relying on the
facts revealed by the microscope in the cavities of the quartz of
this rock, we will endeavour to determine the temperature and the
pressure at the moment of the crystallization of this rock.

The sections of the quartz of Quenast are rich in liquid
cavities, but many of them, besides the bubble and the liquid,
contain little cubic crystals (Fig. 3). An ellipsoidal cavity has
enabled us to measure with great precision by means of the micro-
meter the dimensions of the cavity, those of the bubble and of the
cubic crystal.

Major axis of the cavity .. .. .. .. O,mm00964
Minor axis of the cavity .. .. .. .. 0,00660
Side of the cube af, oo is eo, , ae ODOZT4
Diameter of the bubble .. .. .. ~~... + 0,00187

Of all the rocks subjected to microscopic examination, that of
Quenast is perhaps, after the syenite of Laurvig, the one which

214 Transactions of the Royal Microscopical Society.

presents the greatest number of cavities with these little cubic
crystals, whose faces are sometimes covered with parallel striations
answering to the cleavage p(a0Qo). It would be easy to prove
that these cavities were formed and filled with the substances now
found in them at the very moment of the crystallization of the
quartz. By raising the temperature to about 100° C. we did not
succeed in expanding the liquid; so that it is not liqiid carbonic
acid, but rather a saturated aqueous solution, as Sorby showed.
The little cubic crystals gave rise naturally to the idea that the
cavities are filled with a supersaturated solution of sodium chloride ;
their form and the parallel strize which cover their faces call at once
to mind the crystals of this same salt. .

Following the example of Zirkel, Vogelsang, and Behrens, we
investigated the nature of these microscopic crystals by spectral
analysis. We carefully removed from the grains of quartz ex-
tracted from the diorite all the feldspar which could possibly remain
attached to them. They were hardly put in the Bunsen flame
when they slightly decrepitated, the cavities broke open, and the
ray D appeared; this experiment repeated several times always
gave us the same result. However, in order to be more assured of
the exactness of our research, we wished to confirm it by an entirely
different method. Some fragments of quartz reduced to a fine
powder were put in a test tube of distilled water; when the grains
of quartz had subsided we poured in a few drops of silver nitrate,
the water became slightly milky, and presented the opalescent tint
which characterizes the silver chloride.

Thus we think we can affirm that our experiments demonstrate —
that these cubes are crystals of sodium chloride, and the liquid in
the cavities is a saturated aqueous solution of this salt. This result
is not astonishing, if we reflect upon the analogy existing between
the plutonic and volcanic rocks. The latter almost always, as is
well known, show traces of this salt, and often are impregnated
with it. We will now endeavour to find the temperature at which
this water was enclosed, and therefore that of the rock at the very
moment of its crystallization. We take as the ground of our calcula-
tion the experiments made on the solubility of sodium chloride in
water. It has been observed that the solubility of this salt in-
creases directly as the temperature. The cubic crystals contained
in the cavity having been deposited by the liquid while it was
cooling.

The micrometric measurements of the cavity, of which we have
just spoken, furnished the elements for our calculation. The
volume of the water was found 0,0000002198687 mm., that of
the salt 0,000000098003. We had then only to ascertain to
what temperature we should raise the volume of water to make
it dissolve this volume of salt. On calculation we obtained for our

Microscopical Study of the Belgian Rocks. By A.Rénard. 215

result a temperature of 307° C.* By studying the rate of ex-
pansion of the liquid, Sorby concluded that the quartz in the
trachyte of Ponza must have been formed at about 356° C., which
may be looked upon as a very similar temperature. The number

* Tho volume of the liquid cavity (an ellipsoid of revolution) is 4 7a 0’.
a = 0;mm,00482
b = 0,mm,00330
b? = 0,00001089
ab? = 0,0000000524898

4
3 7 = 41887901

E= ama b? = Ommce,0000002198687

Bubble formula, : ars
r = 0,00093
b= amr = Omme,000000003429
Volume of the cube, ¢ = 0mmc,0000000098003

For the relation of the weight to the volume, we have the following formula:
Water, P = V x 1000; for any given body, P = V x 1000 x specific gravity.
In these formule, when V represents cubic metres, P denotes kilogrammes. Conse-
quently if V denotes cubic millimétres, P represents thousandths of milligrammes,
Hence -

~ {000 x specific weight

p denoting the weight of water contained in the cavity, w the weight of the salt
(without the cube), we have at the temperature of these micrometric determina-
tions, and admitting that in the solution of salt there is neither augmentation nor
diminution of the total volume,

nes w =
1000 * 1000 + 2,26 —

2,26 is the density of salt at 0°; at 20°, the temperature at which the micrometric
measurements were made, this density is less than the zero-value by some
thousandths. We have neglected this slight variation. A similar allowance
must also be made for the water. According to Regnault (‘Chimie,’ t. i. p. 456,
table), at 0°, 100 grammes of water contain, when saturated, 35,5 grammes of
salt; at 120°, 100 grammes of water, when saturated, 40,5 grammes of salt.

Moreover, the solubility increases in proportion to the variation of temperature;
this gives an increase of ,&, grammes of salt for a variation of 1°. Consequently,
at 20°, 100 grammes of water contain 35,5 grammes of salt +22; that is, 36,33
grammes.

We have then the equation,

v

EK — (L+ C) = 0,000000206644 [a]

w» 36,33
ae b
p 100 (]

By representing the weight of the cube by q, and the temperature at which
the cavity was formed by ¢,

: t
phan einer

po SP 100 (¢]
*p’ The

216 Transactions of the Royal Microscopical Society.

307° C. would be exact if the law of solubility of salt in water
already referred to, was well established for high temperatures.
Unfortunately experiments are wanted here. The law of solubility
of sodie chloride remains constant to 120° C.; above this we
are ignorant of its behaviour. Considering that superheated water
becomes a powerful dissolvent of artificial glass in the experiments
of MM. Daubrée and Sorby, we are led to believe that its action
upon sodic chloride is greatly augmented at 200° or 300°. The
doubt upon this fundamental point permits us to assign to our
number 307° only an approximative value. Accepting this as
such, we will continue our examination of the physical conditions
under which the crystallization of this rock has taken place.
This is an example of calculation which will hereafter doubtless
give results on which we can confidently rely. Knowing the
temperature at which the cavity was formed, we can determine
the pressure necessary to prevent, at this temperature, the com-
plete evaporation of the water. It suffices to apply the formula of
M. Roche.*

@

The equation [a] pives p + 296 = 0,000206644
?
” [5] 5, w = 0,3633 p
10
Hilda Tel oa) Bente 24{ Or bs 35,5}
p = 0,000178
w = 0,000064
q = 0,000022
“= = 0,488.
Hence t = 24 (48,3 — 35,5) = 24 x 12,8
i SUiles

* The theoretical formula of M. Roche is the same as that found by Clapeyron,
August, De Vrede, Holtzmann. ‘This formula,” says M. Regnault, “represents
the elastic force of aqueous vapour for a great extent of temperature with remark-
able accuracy; it, indeed, between 100° and 220°, gives a result for the elastic
force too great, but the greatest error only amounts to 35 millimétres. It is
applicable perfectly to the vapour of water, and also to the vapours of alcohol
and ether.” M. Roche’s formula is as follows:

zx

F=aaitm

In this formula w represents ¢ + 20°, t being the Centigrade temperature
counted from the melting point of ice as zero, and according to Regnault’s
calculations :

m = 0,004884085

log. a = 0,0386182275
log. a = 1,9590414

Microscopical Study of the Belgian Rocks. By A. Rénard. 217

We obtain for our result a pressure of 66291 mm., or 87
atmospheres.

Another very interesting rock on account of its microscopical
constitution is that which was designated by Dumont as hyper-
sthenite of Hozémont ; having found that it contains diallage instead
of hypersthene, this rock should be called Gabbro. Chemical analysis
has demonstrated that here the feldspar is labrador feldspar. In
certain cases the thin sections of this gabbro show us the crystals
of labrador broken; the broken parts are slightly separated from
one another; and, what is important for our interpretation, the
surrounding minerals and the base present the aspect of a mass
bent, as is seen in the rocks of true volcanic character which have
a fluidal structure (Fig. 4). The diallage such as we have found
here should not be confounded with hypersthene, on account of its
want of dichroism and because we find frequently the cleavage cor-
responding to h' (cP) associated with another cleavage per-
pendicular to the former. This second cleavage is indicated merely
by irregular and interrupted strize which correspond to the plan g'
(oP) (Fig.5). This second cleavage, as is well known, is less
easy than the other. Hence we never have the regular reticulated
structure which should be found in augite. This diallage is fre-
quently surrounded by little fibres of hornblende 0,3 mm. in length
(Fig. 6). This fibrous hornblende is colourless, perfectly trans-
parent, and dichroic. The minerals which constitute this rock
are imbedded ina greenish substance, which under the Nicol prisms
appears in some places monorefringent, and in others presents a
sky-blue colour. Upon close examination this substance is found
to be of a fibrous structure and offers an irregular network similar
to that which is well known in the case of serpentine; although we
have not met with olivine whose decomposition would have given
the explanation of the presence of serpentine. Besides apatite we
have also detected ilmenite, remarkable on account of its decomposi-
tion products, and which we will now briefly describe.

The sections of this titanic iron are surrounded and covered in
some cases with coatings of an opaline substance perfectly homo-

for b= 307 1 + ma = 2,597095795
m
ra 129,91
x
log. F = log. a + i ares, a

log. F = 1,9590414 + 125,91 x 0,38618275
= 1,9590414 + 4,86241700
= 4,82145840

F = 66291m = 87 atmospheres.

218 Transactions of the Royal Microscopical Society.

geneous, which seems a result of the decomposition of ilmenite.
The first stage of this decomposition is represented by the appear-
ance of whitish veins running through the mineral ; a second stage
exhibits it enclosed in the opaline substance ; finally, the metamor-
phosis can be pushed so far that nothing more is visible except a
few black specks (Figs. 7 and 8). Its chemical composition has
not been determined, but we have ascertained that it is unalterable
by the action of hydrochloric acid, and therefore it is not carbonate
of iron, as has been taught by some. We are, however, persuaded
that the opinion of Giimbel, who admits that it is not a decom-
position product, cannot be sustained.

In the Cambrian and Silurian beds of Belgium and of the
Ardennes we meet with feldspathic rocks having at the same time a
schistoid and a porphyritic texture, and which appear to be regularly
imbedded in quartzites, slates, and schists. Dumont interpreted
this feldspathic rocks as so many dykes injected between the adja-
cent layers; other geologists have admitted that these schisto-
porphyric rocks were the result of a metamorphic action exerted
at certain points. The stratigraphic study of these rocks in the
Silurian of Brabant and their examination both with the naked eye
and under the microscope have led us to admit for them an elastic
origin. ‘The microscopic characters on which we rely to demon-
strate this fact are that the numerous feldspars in the thin sections
are all without distinction broken or their angles blunted, and
present at both extremities the appearance of fracture. In the
same way the grains of quartz are not terminated by crystalline
lines which have their regular form (Fig. 9). © However, in other
places in the same schisto-porphyric rocks we found indications that
a part of the quartz has crystallized in situ. This latter mineral
with sericite and triclinic feldspar constitute the essential elements
of this rock. Hence we arrive at the same conclusion as Sorby,
who considers some sericitschiefer of the neighbourhood of Wiesbaden
as elastic, and we know besides that the rocks of which we are now
speaking have the same identical schisto-porphyric structure and
the same composition as those described by Sorby.

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( 221 )

III.—A New Microscopie Slide. By M. Ennest VanpEn Broxck.

Communicated by Professor Rupert Jonss, F.R.S.

(Read before the Roya Microscoptcan Sociery, April 5, 1876.)
Piate CXXXVIII.

Tue great inconvenience with the ordinary slides is that in general
there is no possibility, without breaking or squeezing the prepara-
tions, or at least damaging the label and glass cover, of adding to
the mounted specimens or altering the preparation at all.

With the slides uncovered with glass there are the inconveniences
of dust and damage to the specimens.

For good results the observer ought to be able to study the
preparation by both transmitted and reflected light, and to be able
to apply the object-glass at very short distances.

The following plan of preparing slides meets these difficulties.

Seen from above (Fig. I.), the new slide does not differ from
ordinary slides; but turned over (Fig. V.) it shows a different
principle of construction altogether.

Figure II. represents a piece of cardboard, or thin wood, B, of
the size a, b, ¢, d, perforated in the middle. On the edges of this
opening (which may be either round or square) is gummed a glass
cover (Fig. L., 1, m, n, 0), and over its edge is gummed a strip of
paper (red or blue), A, which is folded over below, Fig. Il. Under-
neath the card B is gummed the card C, with its opening @, b’,¢’, d,
Fig. II. Slips of ordinary microscopic glass are cut a little smaller
than the opening a’, U’", c’, d'; see Fig. UI., D. With a little brush
I then coat the glass slips with a thin layer of gum-arabic
mucilage mixed with a little glycerine. Afterwards I cover the glass
D with the paper D’, which has an opening corresponding with
that of the glass cover. (The frame of paper D’ is to prevent the
glass D sticking to the surface B when the glass slide is placed,
with its Foraminifera, or other objects fixed on D, in the cavity
a’, b,c, d’, of Fig. II.) Then I have little oblong frames of very
thin paper, gummed, Fig. IV., E, which are to fasten down the
glass D, and keep it in the cavity a’, b’, ¢, d', and exclude dust.
When finished, the slide has the appearance of Fig. I. above, and
Fig. V. on its under side; and it can be used with either trans-
mitted or reflected light under different circumstances. For extra
large specimens, the perforated cardboard or wooden slips B may
be doubled. To rearrange or add to the specimens, wet with a
small brush the thin silver or tissue paper HK, which is then readily
detached. With the nail, for which a notch is left at a in Fig. I1.,
the glass can then be lifted, and changes made in the preparation ;

222 Transactions of the Royal Microscopical Society.

after which, by replacing the glass D in its cavity a’, b’, ¢’, d’, and
gumming on a new frame of thin paper, the slide is renewed, by
this really simple, though apparently complex method.

The pieces of cardboard and wood, as well as the little frames
of thin paper, can be obtained ready made, and already gummed as
far as necessary, so that numbers may be put together in a little
time.

Gh 22an}

IV.—Measuremenéts of Moller’s Diatomaceen-Probe-Platten.
By Epwarp W. Morusy, Hudson, Ohio, U.S.A.
(Read before the Roya Microscoricat Society, March 1, 1876.)

Since Moéller’s Diatomaceen-Probe-Platte has to some extent become
a standard of reference among microscopists, an estimate of the
variability of the fineness of striation on its series of diatoms may
have a certain interest for those who own or who have occasion to
use the Probe-Platte.

It is obvious that the fineness of striation on an individual
frustule of a given species of diatom mounted in balsam is by no
means the only circumstance which influences the ease of its resolu-
tion with a given optical power and a given manipulative skill.
Even if the same frustule be supposed to be remounted under
different circumstances, differences in the refractive power of the
balsam used may occasion slight differences in what may be called
absolute resolvability ; and different thicknesses of covering glass
and of overlying balsam, by permitting a given objective to work
under circumstances more or less favourable to its best performance,
may occasion slight differences in relative resolvability. Further,
if two frustules of the same species and of the same fineness of
striation are compared under the same circumstances, their resolva-
bility may be greatly affected by differences in the abruptness of
the elevations and depressions which appear as strize. The effect
of causes like those now mentioned is obviously little capable of
numerical statement.

Another cause which affects the resolvability of a given diatom
by a given optical power, is the variation in the fineness of striation
of different frustules of the same species. In the case of prepara-
tions like the one under consideration, where the refracting power
of the balsam used may be assumed to be the same, where the
thickness of the covering glass and overlying balsam is found to
vary but slightly, and where it may be fairly assumed that the
frustules of the same species on different Platten are selected from
a somewhat homogeneous stock possessed of common characteristics
and differing chiefly in the size obtained before growth was stopped,
the difference in the fineness of striation will correspond tolerably
with differences in the distinctness of individual striz, and will be
a better index of relative resolvability than if diatoms from widely
different sources were compared.

For these reasons, as well as for the reason that the fineness of
striation of the diatoms under consideration has a certain intrinsic
interest, the writer has measured the striz on the diatoms of ten
of Moller’s Probe-Platten. ‘The measurements were all made with

VOL. XV. R

224 Transactions of the Royal Microscopical Society.

the same objective; they were made as nearly as was convenient
under the same circumstances; corresponding parts of the different
frustules of the same species were selected for measurement; and
the part selected was noted, so that, if the matter were worth the
trouble, reference could be again made to the identical frustule and
the identical part of it which was the subject of the present measure-
ment. The objective used was an immersion ;'gth made by Tolles ;
when used under the conditions of these measurements, its focal
length was found to be sixty-two thousandths of an inch. The
micrometer used was a cobweb micrometer by Troughton and Sims,
of London ;. the value of a revolution under the conditions obtaining
during these measurements was determined by the mean of twenty-
seven comparisons with a millimeter divided into a hundred parts
by Hartnack, and by a larger number of comparisons with a Paris
line divided into a hundred parts whose author is not known. Care
was taken to make the comparisons include the whole line and the
whole millimeter in such a way as to eliminate the effect of
inequalities in division.

For the first thirteen diatoms of the Probe-Platte, lamplight
was employed except for Platte No. 258; for Platten Nos. 481,
535, 572, 586, and for the unnumbered Platte marked A, lamp-
light was also employed for diatom No. 14; for all others, sunlight
was reflected by a heliostat through cobalt glass upon the concave
mirror of the microscope. In measuring Platte No. 258, the
micrometer was almost always in the tube of the microscope;
with Platten A and 572, it-was always mounted in a separate
holder so that the micrometer could be manipulated without
communicating tremors to the image of the object measured ;
in the case of the rest, the micrometer was mounted separately
whenever sunlight was used for the illumination. When the
micrometer was in the tube of the microscope, its wires were made
to coincide with two striz and the number intervening was counted
two or three times; when it was in a separate holder, the wires
were commonly made to coincide with the same stria, and one of
them was then moved over a certain number of striae which were
thus counted.

Of the somewhat more than five hundred measurements thus
made, three have been suppressed because they did not agree with
other concordant results ; some measurements it seemed superfluous
to communicate, in which case the extremes have been given.

In the case of the diatoms from No. 2 to No. 10 inclusive, mea-
surements were made on two specified parts of each frustule. It is
thought that these measurements are mostly correct to within one
or two units in the first decimal place. In the case of the re-
maining diatoms, two or more measurements were made as nearly

Moller’s Diatomaceen-Probe-Platten. By E. W. Morley. 225

in the same place as was permitted by the fact that the number
of striz counted was usually varied. Here the variations in the
numbers given for the same diatom frustule are mostly due to
errors of observation. These errors were kept as small as seemed
necessary for the purpose; that they could be made much smaller
if required was proved by the result of extra care taken with diatoms
Nos. 19 and 20 on Platte No. 258, where the variations from the
mean were all very small. More time was taken for these two
than for any others of the whole two hundred ; an hour and a half
of lamplight and an hour of sunlight were commonly sufficient for
measuring the diatoms of one Platte.

In the table following, the first column gives the name of the
diatom with its number; the second describes briefly the part of
the diatom where the measurement was made; at the end of the
table certain notes specify this part more accurately in certain cases.
The other columns give the measurements for the Platten named at
the head of each column; the first number gives the number of
strize counted in that measurement, and the second gives the number
of strize in the thousandth of an English inch. Under the names of
the diatoms in this table are given the extremes for each one of the
twenty in the series. In this statement of the extremes, it is
assumed that the measurements for Nos. 1 and 2 are trustworthy
to a unit in the first decimal place, those for the diatoms from
No. 3 to No. 9 inclusive are considered trustworthy to half a unit;
for the remaining diatoms the whole numbers corresponding most
nearly to the fractional results of measurement are given with no
expression of opinion as to the limit within which they are trust-
worthy. It may be stated that the widely divergent result for
Cymatopleura elliptica on Platte A is not due to error; the
result was re-examined after it was noticed that it was thus
divergent.

Of course the amount of variation shown by these measurements
is no index of the extreme variation in diatoms of any one of these
species from different sources. But the variations found may be
fairly assumed to show the order of magnitude of the variation to
be expected among diatoms selected with care from the same source.
It may be expected, for example, that samples of Amphiplewra
pellucida, carefully selected from the same stock, may vary as the
numbers 92 and 95; while it could not fairly be expected that
under these conditions there should be any such variation as from
80 to 110 or 120. ‘The results to be obtained by the use of those
diatoms on the Platte which are shown by the table to vary least
when selected as Moller selects them, may be compared with no very
wide limits of error, as far as such results depend on the fineness
of striation of the diatoms in question. 5

R

B

Transactions of the Royal Microscopical Society.

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227

By E. W. Morley.

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( 228 )

PROGRESS OF MICROSCOPICAL SCIENCE.

A New Mode of Colouring Sections of the Nervous System.—
M. Mathias Duval describes the following method recently pursued
by himself, detailed in M. Robin’s ‘Journal de l’Anatomie ’ (Feb-
ruary 1876). He states that whilst it is generally applicable, it is
especially so with sections of the cerebro-spinal axis. The process
consists of two methods, one of which is very old. It is, in fact, the
addition of the blue coloration of aniline to the red colour of
carmine, from which there results a violet tint more or less intense,
and according to the nature of the parts of very varying degrees of
tinting. Sections thus prepared should be mounted in Canada balsam
or dammar resin. This is how the author proceeds: The section is at
first coloured with carmine, according to the ordinary process; it
should then, to be dehydrated, be submitted to the successive action
of alcohol of thirty-six degrees, and of absolute alcohol. After the
action of the latter it is plunged for a few minutes (from five to
twenty minutes) into an alcoholic solution of aniline blue (aniline
blue soluble in alcohol). In taking it from this bath it is placed
in turpentine to be mounted in the ordinary way. Thus obtained,
the pieces present a fine violet colour, which one would think
too deep, but which present an extreme transparency beneath the
microscope. ‘The nerve-cells and axis-cylinders are indicated with
the most marvellous distinctness. In fact, the author characterizes
this method as compared with the simple preparation with car-
mine, by stating that the new preparation is compared with the old
as a neat water-colour painting is as contrasted with a badly worked
lithograph. The principal advantages of this method may be judged
by what the author says may be seen in the sections: (1) The nerve-
cells and axis-cylinders are of a violet, bordering on red. (2) The
vessels are of a violet, bordering on blue, and are very distinct.
(3) The envelopes (pia mater) which proceed from the pia mater and
penetrate into the nervous centres, are all coloured a pure blue, so
that they are readily distinguished from the rest. The author
promises, in a future number, to express more at length the great
advantages of this method.

Relations of Nerves to Ganglia—A note on this subject has been
recently presented to the French Academy by M. Ranvier, who states
that minute experiments made by the writer have demonstrated to him
that almost all the nerve-tubes which set out from the ganglion-cells,
instead of preserving their individuality in directing themselves
towards the centre or towards the periphery, presented T-shaped
anastomoses with the tubes coming from the posterior roots.

Structure of the Pancreatic Cells, observed during Digestion.—It is said
in a paper by Herr A. Heidenhain, which appears in Pfliiger’s ‘ Archiv’
(vol. x.), that the following appearances were successively presented by
the cells of the pancreas at the different stages of digestion :—1. During
hunger the granular inner zone occupies the larger, the homogeneous

PROGRESS OF MICROSCOPICAL SCIENCE. 229

outer zone the smaller part of the cells. 2. In the first period of
digestion, during which a plentiful secretion occurs, there is diminution
of the entire cells by using up of the granular inner zone, then addition
of new materials to the outer zone, so that this becomes enlarged. 3. In
the second period of digestion, during which the secretion diminishes
and comes to a standstill, there is a new formation of the granular
inner zone at the expense of the homogeneous outer zone, most pro-
nounced diminution of the latter, increase of all the cells. 4. With
long-continued hunger there is gradual increase of the latter to their
original dimensions, and therewith slight diminution of the inner zone.
During the state of physiological activity there is a continual change
in the cells—metamorphosis internally, addition of matters externally.
Internally there is conversion of the granules into secretory constituents,
externally employment of the nutrient materials for the formation of
the homogeneous substance, which again becomesconverted into granular
masses. The average appearance of the cells depends upon the relative
rapidity with which this process occurs. In the first period of change
there is a more rapid consumption internally and more rapid addition
externally: in the second period, the most rapid changes occur at the
limit bet:veen the outer and inner zones, in that the substance of the
former becomes conyerted into that of the latter.

The Development and Succession of the Poison-fangs of Snakes.—A paper
was read at a late meeting of the Royal Society which had been written
by Mr. Charles S. Tomes, M.A., and which is published in the follow-
ing abstract in the last number of ‘ Proceedings of the Royal Society.’

At the conclusion of a paper upon the development of the teeth of
Ophidia, published in the first part of the ‘ Philosophical Transactions’
for 1875, I noted that there were peculiarities, which I had not then
been able to understand, in the succession and development of the
poison-fangs. Having reviewed the literature of the subject in that
and in a preceding paper on the development of Amphibian teeth, I will
pass at once to the description of the special features which distinguish
the development of poison-fangs. Poisonous snakes are divided into
two groups—those which have a shortened movable maxillary bone,
which carries the poison-fang and another tooth ; and those which have
the maxillary bone longer, immovable, and often carrying other teeth
behind the poison-fang.

In the former, or viperine poisonous snakes, the poison-fang is very
long, and, when out of use, lies recumbent ; in the latter, or colubrine
poisonous snakes, it is, from the maxillary bone being fixed, constantly
erect,*

As fresh specimens are indispensable for a complete investigation
of developmental peculiarities, I have only been able to examine one
of the colubrine group, viz. the Indian cobra.

Of it one may say, roughly speaking, that the poison-fangs are
developed just like any other Ophidian teeth, for a description of
which I must refer to my former paper, save only that the tooth-germs
are necessarily individually modified so as to produce the characteristic
canaliculated poison-tooth.

* Giinther’s ‘ Reptiles of British India,’ p. 165.

230 PROGRESS OF MICROSCOPICAL SCIENCE.

But in all the viperine poisonous snakes which I have examined, a
strikingly different arrangement is displayed. Upon the movable
maxillary bone there is room for two poison-fangs, side by side; and
in amacerated skull the tooth in use occupies an extreme position, some-
times on one side, sometimes on the other. In sections displaying all
the soft part in situ, the remaining space is generally occupied by a
tooth which is in process of becoming attached; and, in whatever part
of the area of tooth-development the section be taken, the suecessional
teeth are arranged in pairs, in two parallel series. Thus there will
be a right-hand series, consisting of the tooth in place and of four
successors, and a left-hand series, consisting of the tooth next about to
be in place and four successors.

When a tooth of the right-hand series has finished its period of
work and is about to be shed, it is succeeded by a tooth of the left-
hand series, which comes up by its side, and vice versa. A septum of
connective tissue separates the two parallel series, and is continued
out into the pouch, which conceals the poison-fangs when at rest, as a
free hanging fold: its use appears to be to keep the long axis of the
tooth in the right direction prior to its becoming firmly attached, and
to prevent a right-hand tooth from getting into the place of one of the
left-hand series, and vice versa.

It is obvious that this manner of succession is well adapted to avoid
loss of time in the changing of the poison-fangs, for much can be done
towards the fixation of a new tooth before the old one is detached.
That the succession is both rapid and regular would appear to be in-
dicated by the fact that the successional tooth-sacs are very numerous
(often as many as ten), and that they are arranged in pairs, the two
being almost absolutely alike in size and stage of development. Now
as any given tooth of the one series is succeeded or preceded by its
fellow in the other series, one might expect, if any great interval of
time were to elapse, that the one would be materially more advanced
than the other. When such is not the case, one is led to the inference
that the succession is rapid and also regular.

In the cobra, the new tooth has to come into place and become
attached after the loss of the old one; and this, it may be inferred,
would take much more time. May this not be the explanation of the
feat performed by Indian jugglers with the cobra, and their selection
of this snake for such purposes? A cobra disarmed would remain
harmless for some considerable period ; a rattlesnake similarly treated
would be furnished with a new weapon very speedily.

I have examined specimens in spirit of a few other colubrine
snakes ; and although such examinations are less satisfactory than the
methods which may be pursued with fresh specimens, I believe it will
be found to hold good that in those snakes which have a movable
maxilla carrying but one tooth, the successional teeth are developed
in two parallel series, this being the highest specialization of the poison
apparatus.

On the other hand, in the colubrine poisonous snakes, approxi-
mating more nearly to the harmiess snakes in having a fixed maxilla,
sometimes carrying other teeth in addition to the poison-fang, the

PROGRESS OF MICROSCOPICAL SCIENCE. 231

successional poison-fangs are developed in a single series, like any
other Ophidian teeth.

The development of the individual tooth-germ presents one feature
of very great interest. A poison-fang tooth-germ is first formed, like
any other, of an extinguisher-shaped enamel-organ (derived from an
ingrowth of epithelium, which winds in and out amongst the tooth-sacs)
and of a simple conical dentine-pulp.

As it elongates, a groove appears on one side, which, by deepening
and by the approximation of its lips, becomes ultimately converted into
the poison-canal. The enamel-organ, with its characteristic enamel-
cells, passes without break or alteration into this groove; but still
lower down is the tooth-germ, where the groove has become very deep ;
instead of the prismatic enamel-cells constituting a regular pavement
epithelium, we have a reticulum of stellate cells, just like that gelatinous
stellate tissue which forms so large a part of a mammalian enamel-
organ. That the stellate reticulum is a non-essential structure I have
previously shown; but the occurrence of such a tissue within the
poison-canal, which it wholly occupies, and in which it represents the
prismatic enamel-cells found higher up, strongly suggests the idea
that it is a sort of retrograde metamorphosis of an active enamel-
forming tissue into one which simply fills up a void.

It need hardly be added that a thin layer of enamel is developed
upon the outside of the poison-fang; but none is formed on the interior
of the poison-canal.

The base of a poison-fang is fluted (this is not the case with other
Ophidian teeth), the dentine being convoluted as it is in the base of
the tooth of Varanus, or in a labyrinthodont tooth ; and it is attached
to the bone through the medium of an opaque, ill-defined, calcified
material, beyond which again comes a coarse bone. The fixation of a
tooth is effected (alike in cobra and in viperine snakes) by a sort of
scaffolding of coarse-textured bone, which is very rapidly thrown out
from the surface of its finer textural maxillary bone. This “bone of
attachment,” met with, as I have elsewhere pointed out, in greater or
less quantity wherever teeth are attached by ankylosis, is entirely
removed with the fall of a tooth, and is developed afresh for its
successor.

Nerve-supply to the Thyroid Gland.—In the last published part of
the volume for 1875, of Robin’s ‘ Journal de Anatomie,’ M. Poincaré
states that he has been struck with the great richness of this gland in
nervous filaments of all sizes. This is the more curious, since the
gland presents no remarkable indications either of sensibility or
motility. No doubt the gland contains a large number of vessels,
which require, consequently, many vaso-motor fibres, but the nervous
supply is out of proportion to what may be supposed requisite for this
purpose, and M. Poincaré thinks this peculiarity accounts in some
measure for the close relationship known to exist between the thyroid
gland and the generative organs, and believes that many of them are
of a sensory nature. The nerves form close plexuses surrounding
small islets of the substance of the gland, and the branches passing
to and from the gland stand (as he expresses it) in the relation of

252 PROGRESS OF MICROSCOPICAL SOIENCE.

telegraphic cables between the thyroidean colony and the metropolitan
cerebro-spinal axis. To continue the simile, the colony has itself an
autonomous system of telegraphy, the stations being represented by
numerous microscopic ganglia, with connecting branches which do not
pass outside the gland. The best means of examining the nerves of
the gland he finds to be, not hardening agents such as osmic acid, but
softening and disintegrating agents, and he has obtained good results
from maceration in water acidulated with acetic acid, and slightly
coloured with fuchsine.

The Minute Anatomy of the Thyroid Gland has been very care-
fully worked out by Dr. E. C. Baber, who has been carrying on
investigations on this subject in Dr. Klein’s laboratory. It seems
from an abstract of his paper, published in the ‘Proceedings of
the Royal Society,’ No. 166, that on injecting the lymphatics of this
organ with Berlin blue, by the method of puncture, they present
the following characters: Traversing the gland, chiefly in a longi-
tudinal direction, are large lymphatic vessels provided with valves. In
direct connection with these, and permeating the gland in all
directions, is a dense meshwork of lymphatic tubes and spaces. The
smaller lymphatic tubes run between individual gland-vesicles, the
larger between groups of the same. They accommodate themselves
accurately to the intervals left between the vesicles, and where the
intervals are larger they expand into irregularly shaped lymphatic
spaces. They present no appearance of terminating in blind extremi-
ties, as stated by some authors. Injections with nitrate of silver show
the lymphatic vessels, tubes, and spaces to be all lined with a
continuous layer of endothelial plates. During this investigation it
became necessary to study more carefully the interalveolar tissues.
This led to the discovery in them of a tissue which does not appear to
have yet been described. This tissue, which is designated by the
author by the name of “ parenchyma,” consists of large rounded cells,
each provided with an oval nucleus, found either singly or in groups
amongst the epithelial cells. From appearances presented by the
parenchymatous cells, the author concludes that they originate ex-
ternal to the vesicles by exerting pressure on the epithelial wall of the
vesicles ; they then produce a flattening and absorption of the same,
and finally make their way through it into the interior of the vesicle.

The Structure and Development of Antedon rosaceus.—A very
splendid memoir on the anatomy and physiology of this Echinoderm has
- been contributed to the Royal Society by Dr. Carpenter, and must be
referred to now by our readers, from the utter impossibility of abstract-
ing it without the plates which accompany the paper.* The paragraph
on the mode in which its food is digested may, however, be given.
Dr. Carpenter says that the food of Antedon consists, not of the large
bodies grasped and swallowed by ordinary Starfish, but of minute and
even microscopic organisms; and that the so-called “tentacles” are
entirely destitute of prehensile power was long since affirmed by

* ‘Proceedings of the Royal Society,’ Jan. 20.

PROGRESS OF MICROSCOPICAL SCIENCE. 233

Dujardin, on the basis of observation of the habits of the living animal
and of microscopic examination of the matters ejected from the
vent.

“These statements are entirely borne out by my own careful ob-
servation of the actions of the brachial and tentacular apparatus, alike
in the Pentacrinoid and in the adult condition, and by the microscopic
examination I have repeatedly made of the contents of the alimentary
canal. These consist of minute Entomostraca, diatoms, spores of
alge, &e., but especially, in my Lamlash specimens, of Peridiniwm
tripos (Ehr.), which was usually very abundant in that locality. A
powerful indraught current towards the mouth is maintained by the
action of the large cilia that fringe the villous folds of the alimentary
canal; but this does not extend to any considerable distance; and it is
clear that minute particles are transmitted from the peripheral ex-
tremities of the arms and pinnules, along the brachial furrows and the
radial furrows of the disk, to the neighbourhood of the mouth, where
they come within the reach of the oral indraught. This I have re-
peatedly seen when I have had young Pentacrinoids alive under the
microscope; and although I have been prevented, by the peculiarity
of their position, from detecting the cilia to which the transmission is
attributable, I can scarcely doubt that they belong to the epithelial
floor of the furrows. And when I have detached small pieces of the
soft parts from the arms of the living adult, I have found currents to
be produced in the water surrounding them, which could only be
accounted for by ciliary action. Thus the brachial apparatus may be
regarded, in the first place, as an extended food-trap.”

Blood-globules in Typhoid Fever—M. Cornil has found, in the
blood of the spleen of patients who have died in the third week of
typhoid fever, large numbers of white globules, enclosing red globules
to the number of five, six, or even more in a single cell. Other cells
enclosed granules of hematosine. Although the existence in the blood
of these large cells containing red globules is nothing new, neverthe-
less Cornil is the first to insist upon their multiplication in typhoid
fever. The mesenteric glands, according to Cornil, are always in-
flamed in typhoid fever, in a manner analogous to the acute or sub-
acute inflammation due to suppurative lymphangitis.

Course of the Fibres in the Spinal Chord.—Dr. Schieffendecker gives
the following summary in Schultze’s ‘ Archiv,’ Band x. Heft 4:

I. Fibres passing out in different directions from the white sub-
stance into the grey regions.

A. Fibres, which originate at the same point, and pass over into
the grey substance at different heights. Fs

B. Fibres, which originate at different points of the white sub-
stance, and pass over, at the same point, into the grey substance.

C. Fibres, which belong to the same vertically extending bundles,
and which, at the same height, bend over to the grey substance, often
divide during their horizontal course in the white substance, towards
the right and left, terminating in the grey substance, as bundles of
different character.

234 PROGRESS OF MICROSCOPICAL SCIENCE.

il. Fibres passing in different directions, through the grey sub-
stance, for the purpose of connecting fibres.

A. Simple networks, ea sunt: 1, primary networks at the border
of the white substance, combining the single bundles which have
passed out; or 2, secondary networks, which, situated more in the
middle parts of the grey substance, combine those bundles of fibres
which have formed networks once before.

B. Courses of fibres which combine different large parts of the
chord ; these are:

I. The fibres of the posterior and the anterior commissures which
combine the two halves of the chord.

II. The vertically running fibres of the grey substance which
combine parts of different heights in the course of the chord.

III. Peculiar formations, probably for the purpose of connecting
fibres of different character: the ganglion-cells with the delicate net-
work involving the same.

The Structure of the Stomach.—Mr. H. Watney gives the following
summary of his researches, which will soon be published in the
‘Philosophical Transactions. It relates to the anatomy of the
pyloric end.

1. The surface is seen to present somewhat parallel folds; the
stomach-tubes opening on the summits of these folds are longer than
those which open in the depressions between the folds.

2. The epithelium is described as being closed during inanition,
but open at its free extremity during secretion.

3. The germination of the epithelium is next described. The
conclusions arrived at are :—that the epithelial cells divide ; that the
small rounded cells (other than the lymph-corpuscles) are the pro-
ducts of their division ; that these small cells, increasing in size, rise
up among the older cells, push them to one side and become short
broad cells; that the short broad cells divide longitudinally, and form
groups of two or three, or even more cells, which the author calls
“ epithelial buds.”

4, A reticulum among the epithelial cells is described ; it is found
to be very delicate, and does not extend to the surface.

5. The membrana propria is found to be composed of large cells.

6. The muscle-endings in the plice villose are similar to those in
the colon of the rabbit, already described.

7. Perivascular spaces are found in the upper part of the plica
villose ; these spaces are bordered by endothelial cells: the mem-
brana propria forms the upper wall of the space.

8.:The proper gland-tubes. A fine reticulum is described as
occurring among the epithelium of these glands. The nuclei are
found usually as flattened disks lying at the base of the cells. The
nuclei are, however, during digestion occasionally found to be spherical
in form. A third kind of nucleus was also found, which was possibly
intermediate between the two other forms.

Lignin in Plants.—Herr A. Burgenstein contributed a paper on
this subject to the Academy of Vienna. He states that experiments

PROGRESS OF MICROSCOPICAL SCIENCE. "ae

were made with aniline sulphate, by which he determined the absence
of lignin in fungi and alge. It is found in a very few plant-hairs,
in all wood-cells, but never in cambium. Many bast-cells have
considerable lignin, but the sieve-cells hardly any. The most curious
observation was that the walls of pith-cells in many plants are
lignified, and the medullary rays also.*

The Roots of the Spinal Nerves in Elasmobranch Fishes.—This
subject, which is one of great difficulty, has been lately worked out
by Mr. F. M. Balfour, B.A. It seems that the posterior and anterior
roots of the spinal nerves arise as independent outgrowths from the
involuted epiblast of the neural canal. The outgrowths for the two
roots are at first quite independent of each other, and only unite at a
late period of development. The posterior roots are the first to
develop. An outgrowth arises on each side from the dorsal summit
of the neural canal, which the author believes to be unbroken
throughout its whole length. The outgrowths on the two sides are
at first in contact with each other; and from each there springs a
series of processes equal in number to the muscle-plates.

These processes are the rudiments of the posterior nerve-roots.

They grow ventralwards in contact with the side of the spinal
chord. .
After the formation of the posterior rudiments, the original out-
growths from the spinal chord cease to be attached to it along its
whole length, and remain in connection with it at a series of points
only, each of which corresponds to a posterior root.

The result of these changes is the formation of a series of nerve-
roots, each attached to the dorsal summit of the neural canal, and all
of them united together dorsally by a continuous commissure, which
is the remnant of the primitive outgrowth from the summit of the
neural canal.

Subsequently the points of attachment of the posterior roots
travel down the sides of the spinal chord, and finally remain fixed at
about one-third of the distance from its dorsal summit.

The Placentation of Hyrax.—On account of the differences of
opinion which have been expressed on this point, the subject has been
minutely investigated by Professor W. Turner, who, in a paper pre-
sented to the Royal Society in December last, goes minutely into the
anatomy of this organ. He concludes that as “the placenta of Hyrax,
both in the form of its villi and in the mode in which they are inter-
locked between the intraplacental maternal lamin, so closely resem-
bles that of the domestic cat, and as these laminz remain in situ after
the membrane, which I have named the serotina, is peeled off the
placenta, there can be no doubt that they are shed at the time of
separation of the placenta. Hence Hyrax, in its placentation, is one
of the Deciduata. Whether the membrane just referred to is also
shed during parturition is more difficult to say. The fact that it
peels off the uterus along with the placenta, when they are artificially

* Vide ‘Sitzungsb. der kaiser. Akad. der Wissen.,’ Ixx, i.
+ See ‘Proceedings of the Royal Society,’ No, 165.

236 PROGRESS OF MICROSCOPICAL SCIENCE.

separated, is not of itself sufficient evidence. In the cat the whole
thickness of the mucosa in the placental zone peels off along with the
placenta when that organ is artificially separated ; whilst in normal
parturition the deeper part of the connective tissue of the mucosa,
with the remains of the blood-vessels and tubular glands, persists as
a covering for the muscular coat, and forms a non-deciduous serotina.
It may be that in Hyrax, as in the cat, only the superficial part of
this membrane is shed with the placenta, whilst the rest remains on
the zone of the uterus; but this can only be determined by the
examination of a uterus immediately after parturition.”

The Rotifer within the Volvox.—The following observations are
taken from a new American periodical devoted to microscopical
science. The writer says that having watched the above phenomenon
on one or two occasions, “and being desirous of keeping a few volvoces
for future examination, and having formerly had very poor luck with
such attempts, I took especial pains this time. I scalded two bottles
thoroughly, and partially filled them with boiled water. When quite
cold I placed a dozen volvoces in one bottle, taking them up with as
little of the original fluid as possible. After an hour or two I trans-
ferred them, one by one, from the first bottle to the second, where
they are now probably alone, and are thus far doing well. I examined
each one carefully when first caught, and what was my astonishment
to find several with rotifers in ‘their interior, the rotifers being ap-
parently very busy making a meal. That the inhabitants of these
volvoces were rotifers, there can be no doubt. Carpenter describes
the presence of amcebz in the volvox, and explains it by stating that
the endochrome-mass of one of the ordinary cells has assumed this
condition. The phenomena which I have just seen certainly can-
not be thus explained, and I feel puzzled to know how the rotifer got
inside the volvox, while the latter appears to be unbroken and con-
tinues to swim about in the usual manner, carrying the strange
‘entozoon’ with it. That the rotifer is inside is easily shown by
focussing down through the volvox. First we see the upper surface
of the volvox, then the rotifer, and lastly the under surface of the
globe.”

How to Measure the Angular Aperture of Object-glasses.—There are
many who possess the microscope with most of its accessories to
whom the above question would prove a very formidable one in-
deed. We think therefore that the following condensed account, which
has been given by Mr. Ingpen in the ‘Journal of the Quekett Club’
(January), which very briefly and clearly defines the various methods
employed will not be without interest :—Down to the year 1854 the
method of measuring angular apertures devised by Mr. Lister seems
to have been the only one employed. This is described in the ‘ Phil.
Trans.,’ vol. cxxi., p. 191, and will be found in ‘ Quekett on the
Microscope,’ ed. 1855, p. 497. The microscope, with its objective and
eye-piece as in ordinary use, is placed horizontally, a candle is set on
a level with it, a few yards distant; the microscope is then turned,
till, on looking through the eye-piece, the field of view is bisected,

PROGRESS OF MICROSCOPICAL SCIENCE. 2a7

half being light and half dark. The microscope is then turned
round, with the focus of the objective as a pivot, until the opposite
half of the field is illuminated. The angle can be measured by lines
drawn on a suitable part of the instrument, or, preferably, by a
divided semicircle. This method answers very well up to 90° or 100°,
but for larger angles is not nearly so accurate as that devised by Mr.
Wenham, and described in the ‘ Quart. Journ. Mie. Sce.,’ 1854, p. 134.
A lens of about a} in. focus being placed centrally, in a sliding cap,
above the eye-piece, the image of the flame can be observed, and the
angle measured with great accuracy ; also the condition of the defini-
tion at the margin of the field can be ascertained, sometimes suggesting
the utility of reducing the angle of the objective. This plan appears
to have been used some years earlier by Amici. In the ‘ Quart.
Journ, Mic. Se., 1854, p. 293, Mr. Gillett’s method is described :
this was communicated to the Royal Society on March 9, 1854. The
cye-piece is replaced by a cone having a small aperture, through which
light is sent. The objective is focussed on an object which forms the
centre upon which a second, or examining microscope, attached to a
divided are, turns. This plan is described in Mr. Hoge’s ‘ Treatise
on the Microscope,’ 1871, p. 45, as “a very perfect instrument,” but
there seems to be some source of error connected with the employ-
ment of a second microscope. Professor Robinson’s method was first
brought before the Royal Irish Academy in 1854, and is described in
the ‘Quart. Journ. Mic. Sc.,’ 1854, p. 295. Rays nearly parallel
are sent through the eye-piece and objective, and intercepted by a
screen at a distance greater than the focus. This distance, and the
diameter of the base of the cone of rays so formed being known, the
angle is easily calculated. This is a very elegant method, and likely
to be valuable in certain disputed cases as to the true angle of immer-
sion lenses. Mr. Sollitt describes a method, in the third volume of the
‘Quart. Journ. Mic. Sc.” 1855, p. 85, which he considers simpler
than Mr. Wenham’s. He does not use the Huygenian eye-piece, but
a lens of 14 inch focus, “as the eye-piece of a diminishing telescope.”
Two candles are employed, and moved till their images are seen at
the extreme edges of the field. This is described in ‘Carpenter on
the Microséope, 5th ed., 1875, p. 202. It is open to the objection
that if the observing lens is held obliquely, a distorted image of
the candle may be seen at a greater angle than that which is engaged
in forming the image of the object, and probably the angle is over-
stated. Mr. Wenham’s (or Amici’s) method seems to have been again
re-invented, as it is attributed by Mr. Brooke (‘ Quart. Journ. Mie.
Sc., 1864, p. 84.) to Professor Govin, of Turin. It was used in the
examination of objectives at the International Exhibition of 1862;
the only differences were the employment of a combination of two
lenses instead of a single lens, the instrument being placed in a
vertical instead of a horizontal position, and strips of white paper on
a dark cloth used instead of candles. In the ‘Quart. Journ. Mie. Sc.
vol. vii., p. 256, Mr. Peter Gray examines the images of two flames in
the objective without an eye-piece, which amounts to a re-invention of
Mr. Sollitt’s method. Mr. Stephenson, adopting the same system,

238 PROGRESS OF MICROSCOPICAL SCIENCE.

places two flames, such as night-lights, at known distances apart, and
using the objective alone without any tube, has a very convenient
scale of tangents engraved upon paper, thus showing the angle by
inspection. This is described in the ‘Month. Mic. Journ., July,
1875, p. 3. In the ‘Month. Mic. Journ.’ for May, 1874, p. 178,
Mr. Wenham describes an adjustable slit formed by two slips of very
thin platina foil, which can be separated to the exact diameter of any
field of view, thus excluding all but “ image-forming rays.” This is
a very valuable adjunct, and greatly conduces to accuracy ; and when
used with a divided circle, with small flames at a suitable distance, or
white crosses on a black ground, and with a lens or lenses centered
and sliding above the eye-piece, it forms a very suitable and accurate
combination.

The Development of Gasteropod Mollusks.—We learn from a note in
the ‘ American Naturalist’ for March, that at a meeting of the Boston
Society of Natural History on February 2, Dr. W. K. Brooks read a
paper on the development of Astyris (Columbella) lunata. This, that
journal states, is the first siphonated gasteropod whose embryological
history has been followed. Some general views on the molluscan
pedigree were added.

State of Chord in Death from Paresis.—Dr. C. E. Mann says * that
in a recent case of death which occurred in a person who suffered from
Paresis, upon hardening the spinal chord and making thin sections, and
employing carminal staining to demonstrate the structural relation
more clearly, there were found to be, upon microscopical examination,
atrophy and degeneration of the nerve elements of the posterior
columns, with increase of connective tissue. Sections of hardened
brain-tissue being made, there was observable, in the cerebral cells of
the frontal convolutions, a diffused granular degeneration. No change
could be detected in the cerv'cal sympathetic, which was carefully
examined,

Difficulties of Classification of the Spongida.—Mr. H. J. Carter, who
has recently written upon this subject, says, in a report published in
the ‘Annals of Nat. Hist.,’ that in the general classifieation of the
Spongida there is not much difficulty, as the skeleton (which too often
is the only part that reaches us, from the inaccessible places in which
many of them grow and the accidental circumstances under which
they reach the shore) consists of durable material which, in structure
and composition, admits of very easy arrangement; while where there
is no skeleton at all, this alone for such sponges is sufficiently
characteristic of the order. But in the more particular classification
there are peculiar difficulties, inasmuch as there is no expression in
sponges as in other animals and in plants; that is, there is nothing
like a calice, as in the coral, and nothing like a flower, as in the plant,
to guide us—what there is in this respect, viz. the spongozoon, being
microscopic in size, undistinguishably alike and so’protean in form as
only in its active living state in situ, or just after it has been eliminated

* “New York Med. Journal,’ February.

PROGRESS OF MICROSCOPICAL SCIENCE. 239

from the sponge, distinguishable from a common amceban animal.
Again, as regards the general form of the sponge itself, there are
many instances where the same form may be assumed by totally
different species, and the same species assume different forms, so that
a microscopical examination of the “proper spicule” can alone
determine the species; thus a fan-shaped and a vase-like form re-
spectively may have at one time the same, and at another a different
form of spicule. And yet again the aid derived from the form of the
“proper spicule” is confined to sponges so provided, while those
which have nothing but foreign objects instead of the “proper
spicule” are even without this aid. So that, after all, we may be
thrown back upon structural peculiarities in combination with
general form, and perhaps sometimes colour, for ultimate distinction.
(This will be found to be particularly the case with the Hircinida.)

Still there are many instances where the same species may be
hastily recognized by its outward features; but as this can only be
done after much experience, it is of no use toa beginner. At the
same time, from what has been above stated, it would always remain
uncertain, even to the experienced, without a microscopical examin-
ation.

A fresh sponge, too, described in its natural state (that is, with the
sarcode on), differs greatly from that in which the sarcode is off, or
where the skeleton only remains. As, however, by far the greater
number of sponges come to us in the latter state, and, indeed, all must
be divested of the sarcode before they can be usefully described for
classification, seeing that, as before stated, there is no animal ex-
pression (so to term it) externally or internally that can be made use
of for this purpose, it seems best to describe the skeleton naked,
rather than under cover of the sarcode—that is, to describe the
skeleton only, although, of course, where this can be done with the
sarcode on as well as off it is best of all. But there is no doubt that
a description of the sponge with the sarcode on will never serve to
recognize its skeleton, which is at once the most charactcristic and
frequently the only part that we can or are ever likely to obtain from
the inaccessible localities in which many grow; so after all we. are
not so badly off with the skeleton only, provided it has not been worn
away by much attrition. Hence the fundamental divisions of my
arrangement will be based on the characteristic features presented by
the elementary composition of the skeleton or organ of support. It
should not be forgotten, however, that with the sarcode of course the
flesh-spicules disappear, falling through the skeleton, as before stated,
like small pebbles through the meshes of a fishing net, when the
sarcode passes into dissolution. Nor should it be forgotten that
there may be a great difference between a sponge in its “fresh” and
in its dried state, in size, colour, and general appearance. As the
sarcode in all assumes the character of glue when dry, those which,
like the Carnosa, are without horny skeletons can only be described
when fresh or preserved in some aqueous solution. Also sponges
possessing a skeleton sink down in many instances to half their
original size by the shrinking up of the sarcode, which, clinging

VOL. XY. 8

240 NOTES AND MEMORANDA.

round the skeleton, destroys the original plumpness of the sponge,
and thus alters considerably its general appearance externally as well
as the structure internally. Lastly, the colour under drying, as
before stated, may fade in part or altogether. Still there are some
things in a sponge which are seen better when dry than when fresh.
Such difficulties beset no other classification in natural history. But
what is to be expected otherwise, when, in addition to this, the
protean character of the sponge, whose transformations are endless in
the soft parts, and only approached in number by being stereotyped
in the harder ones, is considered ?

w

NOTES AND MEMORANDA.

Soiree of the Royal Microscopical Society.—On the 21st of
April, through the courtesy of the President, H. C. Sorby, Esq., F.R.S.,
was held one of the most brilliant evenings that the Royal Micro-
scopical Society has enjoyed for many years. Ladies as well as
gentlemen were admitted, and it is but just to say that the microscopic
specimens exhibited were both vast in number and exceedingly original
in character. All the arrangements were of the most consummate
excellence, and the whole affair will be fully reported in our next
number.

American Postal Micro-Cabinet Club.—We learn that a year’s
experience in the working of this organization has already given it
the position of a useful and well-sustained institution. The first an-
nouncement of the formation of the club was so favourably received,
that an unexpectedly large number of members was enrolled, since
which time its membership has steadily increased until it now numbers
twelve circuits of members, distributed over tae whole country east of
the Rocky Mountains. With the exception of a remarkably small
number of accidents to objects while in transit by the mails, which it
is believed will be still fewer in the future, the club has met with no
practical difficulties or disappointments. The general excellence as
well as the variety of objects contributed has been conspicuous; and
those members, if there are any, who can learn but little from the
work of others in various departments of the science, must at least feel
that they have contributed widely to the advantage of others at very
little trouble to themselves. In addition to the circulation and study
of mounted objects, critical notes upon the same, questions and
answers, and announcement of duplicates for exchange, it is proposed
to add during the present year the exchange of microscopic objects
and material, whether mounted or unmounted, not necessarily con-
nected with the slide contributed ; any member adding at the bottom

CORRESPONDENCE. 241

of his note a statement of offers or wants, and other members
addressing him directly by mail, in regard to the same.

Instructions for Cleaning Foraminifera of the Chalk—
Mr. C. J. Muller kindly sends us the following note :—Having obtained
a quantity of the shells by the usual process of elutriation, mix it with
four or five times its bulk of silver sand which has previously been
well washed, and put the mixture in a long 2 or 3 ounce phial with a
sufficiency of water. Shake up the whole (not violently) for ten or
fifteen minutes. Let it rest for three or four minutes, and then pour off
the turbid water. Renew this operation as many times as you like. The
Foraminifera will always settle down last, and form a distinct stratum
upon the surface of the deposited sand. The sand when shaken up
with the shells will act as a gentle rasp, and remove from their
surface most of the hard granular particles which injure their appear-
ance. When the cleansing operation is completed, the water will
rapidly clear upon the mixture being set aside for three or four
minutes.

There is no difficulty in separating the shells from the sand. Let
the whole quietly settle down; pour off the clear water, and allow
the whole to rest for a few minutes. Now add a fresh supply of
water rather forcibly, when the shells will immediately rise, leaving
the sand below. The water with the shells must now be poured off,
before they have time to settle down, into another vessel where they
may subside. The deposit may then be dried and mounted in
dammar or Canada balsam in the usual way.

CORRESPONDENCE.

Proressor Kerrn’s CRIvicisM.
To the Editor of the ‘ Monthly Microscopical Journal.’

Sir,—I am quite willing to meet fair discussion relating to the
principle on which I have asserted that the measured apertures of
all object-glasses have hitherto been greatly in excess of the true
angle.

pectin Keith’s letter in your last issue appears somewhat
superfluous, as it does not in any way help to elucidate the point.
First, merely on his own judgment, he attributes “ errors” to me—
not considering that such have yet to be proved.

The remainder of the letter resolves itself into the assertion that
it is “possible to compute the spherical aberration of any com-
bination of lenses, and with any degree of accuracy.” Very well; I
‘shall be glad if this can be done, so that the tedious trial and error

ee

242 CORRESPONDENCE.

method still carried on in the workshops for effecting new com-
binations may be dispensed with, by a previous computation “ not
difficult.”

Of course there is but little use in such a calculation if anticipated
by the practical result to which it is applied.

Yours very truly,
F. H. Wennam.

ZEIss’ OBJECTIVES.

To the Editor of the ‘ Monthly Microscopical Journal.’

66, KinespowN ParabDE, Bristou, April 10, 1876.

Srr,—If in the note published in your February number (p. 96) I
had invidiously pitted the Zeiss dry objectives against Powell and
Lealand’s new immersion, I must have acknowledged myself open to
Mr. Hickie’s courteously expressed strictures. As, however, my remarks
can hardly be so interpreted, I demur to the indictment. I went, in- ©
deed, a little out of the way to do justice to the Zeiss lenses (as I
considered they fully deserved), for my concern was to vindicate the
new 3th from an unmerited charge of want of penetration, which is
practically tantamount to limited usefulness. Now penetrative power
is usually considered to increase as the angular aperture is lessened ;
a belief which these Zeiss glasses of remarkably small angle seemed
capable of putting to a severe test. It was in the one quality of
penetration that I compared the 1th with the Zeiss lenses, and these
were bound to be dry ones, as no low-angled immersions are made
either by him or others. That the Powell and Lealand glass should
fully equal them in penetrative power was, I confess, an agreeable sur-
prise, which I think few would have anticipated. I made no com-
parison between the relative resolving powers, as this would have
been manifestly unfair towards glasses of little more than half the
angular aperture of the new ith; but I may say that even in this the
dry Zeiss lenses appear to be satisfactory. I have not tested them
very critically myself, but while I was at Sidmouth last aitumn, the
Rey. Lord 8. G. Osborne showed me fine “resolutions” with a dry
Zeiss 1th skilfully manipulated, and he writes me that he has since
greatly surpassed them by the aid of some newly-devised arrange-
ments.

I was led to mention the amplification of the Zeiss glasses, not only
because, as Mr. Hickie indicates, the foreign numbers convey no in-
formation to us, being taken at a much shorter distance than our stan-
dard 10 inches and with lower eye-pieces, but also because my figures
do not agree with those given by Zeiss. He states the diameters
yielded by his }th and jth to be x 330 and x 500, whereas I
found them as x 330: x 451, showing that one must have been con-
siderably over- or the other as much under-estimated. Possibly
different specimens of his lenses, nominally the same, may vary in

CORRESPONDENCE. 243

power between themselves, which is, I am sorry to say, not unknown
amongst our own makers. This never tends to inspire confidence in
the accuracy of the rest of the work, and that it is by no means un-
avoidable is proved by the closeness of Messrs. Powell and Lealand’s
working. These gentlemen made me a special 1 inch of 20° and
4 inch of 40°, and I found the power to be (with their No. 1 ocular)
x 52 and x 105 respectively; their catalogue giving the round
numbers x 50 and x 100.

Undue discrepancies in amplifying power may cause confusion in
purchasing lenses. I may name a case in point. Through the kind-
ness of Mr. Wenham I became the fortunate possessor of the original
3th which he had worked up to 120° on his new principle. The ex-
quisite defining and resolving power of this particular glass rendered it
a most valuable acquisition, but it fell short in one respect. I
imagined that in it I was adding to my series a power a step higher
than my Andrew Ross }th (1854), but I found it, in fact, very much
lower. With Ross’ B ocular at 10 inches, and with the screw-collars
set half-way, the 1th gave x 406,and the }th x 360 only. This could
not have been surmised from any published list, since A. Ross’s
catalogue of 1853 gives his 1th with B = x 350, while Ross and
Co. in 1872 set down their 1th as x 425 and in 1875 as x 400.

While on the subject of amplification I may be excused for alluding
toa point which I have reason to know is occasionally misappre-
hended, however trite it may appear to the bulk of your readers. The
published lists of magnifying power in the opticians’ catalogues must
not be supposed to furnish even a rough approximation to the amplifi-
cation with which an object will be seen in the microscope with those
objectives. To admit of comparison, these lists are compiled on the
conventional assumption that the distance from the eye-lens to the
stage is always uniformly 10 inches; whereas with low powers and
long bodies it may really reach 16 or 18 inches, with a proportionate
increase in magnifying power. Hence every microscopist should work
out for himself two tables of the power of each of his objectives with
his various oculars; one at 10 inches to compare with published lists,
and the other, and by far the more important one, at the working distance
in each case. It is almost superfluous to hint how this is done. The
microscope being set horizontally, the paper on which the images of
the stage-micrometer lines are to be marked, is placed in the first case
exactly 10 inches below the centre of the reflecting surface of the
camera, and in the second, exactly as far from it as that is from the
surface of the micrometer, when the images of the lines (or the out-
line of any object) will be traced of precisely the same size as they
would appear to the eye on looking through the instrument in ordinary
work. “Personal equation,” however, comes into play here. The
magnifying power as determined by a long-sighted and a short-sighted
observer will vary by a very notable constant difference. In all such
trials the screw-collars (if any) should be set to the same point in
each case, or serious discrepancies may arise, perhaps not always
unintentionally,

Such elaborate comparisons between different objectives as those

244 PROCEEDINGS OF SOCIETIES,

given by Mr. Hickie are very valuable to workers if thoroughly per-
formed and conscientiously reported ; but I may be pardoned for sug-
gesting that in future cases they would be still more useful if a typical
glass of some English maker were included in the trial. Many who
may be hesitating between investing in, say a Powell and Lealand
and a cheaper Zeiss or Gundlach, would be glad to gain some notion
as to how much they would lose in quality by choosing the latter,
though they might be supremely indifferent as to the precise relative
value of the work of Seibert or Schieck—names almost unknown
here. Moreover, if Zeiss were paramount among his compatriot
makers, we must not forget that the one-eyed would be king among
the blind.

I presume Mr. Hickie* means the ordinary silvered mirror, and
not a silver speculum.

Mr. Dallinger doubtless (though he does not name it) has some
arrangement for constantly placing his new lamp and the microscope in
the same relative position, as by dropping them into sockets in a base-
board, since that would greatly facilitate adjustment. The supple-
mentary stage he speaks of is probably similar in principle to that
which I described in ‘M. M. J.’ six or seven years ago in connection
with Reade’s diatom-prism, and which I find eminently serviceable.

I am, Sir, yours obediently,

FrepDErIck W. GRIFFIN.

PROCEEDINGS OF SOCIETIES.

Royau MicroscoricaL Society.

Kine’s CoLieee, April 5, 1876.

H. C. Sorby, Esq., F.R.S., President, in the chair.

The minutes of the preceding meeting were read and confirmed.

A list of donations to the Society since the last meeting was read
by the Secretary, and the thanks of the meeting were voted to the
donors.

The President said they were favoured that evening by the
presence of M. Rénard, of Louvain, who was the author of the paper
to be read on that occasion; he had, however, preferred rather to —
have his paper read than to read it himself, therefore Mr. Charles
Stewart would kindly undertake to do this.

Mr. Charles Stewart then read the paper by M. Rénard, “ On Some
Results from a Microscopical Study of the Plutonic and Stratified
Rocks of Belgium.” The paper was illustrated by an explanatory
drawing made on the black-board by the President, and by a series of

* Foot of p. 193.

PROCEEDINGS OF SOCIETIES. 245

beautifully executed chromo-lithographs, which were handed round
for the inspection of the Fellows. (The paper is printed at p. 212.)

The President felt quite sure that it would be the pleasure of all
who were present to return their thanks to M. Rénard for his
admirable paper ; and they would do so with the greater satisfaction,
seeing that it was not often they had the advantage of a paper from
a distinguished foreign gentleman. The subject was one of much
importance in geology ; indeed, there were few considerations of more
importance than the temperature at which these rocks were formed ;
and he thought they might well congratulate themselves upon having
brought before them the first paper which had been written upon the
subject of a new method of obtaining this temperature. He felt
personally much gratified to find that the results arrived at by
M. Rénard agreed so nearly with those which he had himself obtained
some time ago by a totally different process, his calculations being
based entirely upon the ratio of expansion of liquids, making the
cavities, in fact, act as self-registering thermometers. (Diagram
drawn on board.) When now examined, the cavities were found to be
only partially filled with fiuid, and he had proceeded to find the
temperature necessary to expand the fluid sufficiently to make it fill
the cavity entirely. He thought it worth noting that M. Rénard’s
temperatures may not be the actual temperatures at which the rocks
were formed, because he assumed that the liquid was in a state of
saturation ; but if this were not actually the case, then M. Rénard’s
calculation may be really less than the true temperature, though it
was clear that whatever that might be, it could not be less than that
assigned by M. Rénard. Considering the nature of the two methods
employed, that they were conducted upon entirely different bases, and
were independently arrived at, he thought the results were very
remarkable, M. Rénard having found the temperature to be 807° C.,
whilst he had himself placed it at 356° C., or a difference of only 49° C.
These figures seemed to show that those rocks had not been formed at
‘such a high temperature as some geologists had thought possible.
It was, in fact, not more than a dull red heat—a heat so dull as to
give out scarcely any light in the dark. He thought they must
certainly congratulate themselves upon having such a paper, and upon
having it brought before them for the first time.

The cordial thanks of the Society were unanimously voted to
M. Rénard for his paper.

The Secretary called the attention of the Fellows to an improved
form of microscope and mounting lamp, designed by Mr. Sear and
manufactured by the Silber Light Company, which was placed on the
table for exhibition. It gave a very powerful light from a silber burner ;
and in addition to this advantage it had a heating table placed over
the lamp, on which slides might be warmed or dried as required.

The Secretary said they had received a short paper from Professor
Rupert Jones—written by M. E. von Broeck—describing a new kind of
slip for mounting opaque objects. It was a contrivance for fastening on
the glass cover by means of tissue paper, in such a way that it might
easily be removed if it became necessary to get at the specimen,

246 PROCEEDINGS OF SOCIETIES.

which could not be done if the cover were cemented down in the usual
way. The paper would be taken as read, and of course it would appear
in the Journal, (See p. 221.)

The thanks of the Society were voted to Professor Rupert Jones for
his communicaticn.

The Secretary then read a paper which had been received from
Dr. J. J. Woodward, of the United States’ Army Medical Department,
“On the Markings of Navicula Rhomboides.” 'The paper had special
reference to the remarks made by Mr. Hickie at a former meeting of
the Society, and some very beautifully executed photographs in
illustration had been forwarded with the MS.

The President felt sure all would unite in voting their cordial
thanks to Dr. Woodward for his paper. He was for his own part
extremely glad to have an opportunity of seeing these very beautiful
photographs; he only wished that in this country they could photo-
graph these things as well.

The thanks of the meeting were unanimously voted to Dr. Wood-
ward for his paper and the accompanying illustrations.

In answer to the President's request, Mr. John Mayall, jun., said :—
I think it is perfectly evident from the reasoning in Dr. Woodward's
paper, that the diatom which Mr. Hickie calls Frustulia Saxonica is
identical with the Rhomboides which Dr. Woodward has photo-
graphed from Moller’s Typen-Platte, copies of which are before us.
The photographic evidence here adduced is of a novel character, so
far as I know, in deciding a question of identity of form and definition
in a microscopic object. Mr. Hickie exhibits photographs of a diatom
which he calls Frustulia Saxonica ; Dr. Woodward examines copies
of them, and finding the strie— or rows of hemispherical beads—to be
of just about the same degree of fineness with those on the Rhomboides
when the whole diatom is magnified so as to be of the same length,
he comes to the conclusion that the objects photographed must have
been practically the same. So far as similarity of outline and
definition can make out a clear case for the identity of two diatoms, I
consider Dr. Woodward has succeeded in proving that Mr. Hickie’s
Frustulia Saxonica is simply a coarse form of Rhomboides. Every-
one who is familiar with the Frustulia Saxonica— photographs of
which Dr. Woodward sent in illustration of his paper in December—
knows it to be one of the most difficult test-objects, a diatom that
ranks next to Amphipleura pellucida. That particular form of
Frustulia is one that I have rarely seen resolved except by lenses of
the highest excellence. I considered Dr. Woodward’s photographs
of it as in every way most remarkable, evincing first-rate skill brought
to bear on one of the finest known lenses. I am unable to com-
prehend the grounds on which Mr. Hickie seeks to depreciate those
photographs. That he should for an instant appeal to Seibert’s
photographs of Rhomboides—or as he chooses to call the diatom,
Frustulia Saxonica—as being finer examples of manipulative skill,
proves to my mind that he knows little or nothing of the difference
between obtaining clear images of an easily resolved diatom, and
similar images of a really difficult object—one that taxes the lens to

PROCEEDINGS OF SOCIETIES. 247

very nearly the limit of its power. In Seibert’s photographs of
Rhomboides, the diatom was of quite easy resolution, and yet by
mismanagement of the illumination an imperfect definition was
obtained. This is clearly seen by comparison with Dr. Woodward’s
photographs. Here Dr. Woodward has taken in hand a Rhomboides
in every respect corresponding to Mr. Hickie’s diatom, but instead of
mere transverse and longitudinal lines which are not the true resolu-
tion, he exhibits rows of hemispherical beads with a clearness and
definition that unmistakably show that he stands unrivalled in the
work he has made peculiarly his own. With these photographs before
me, I can only conclude that Mr. Hickie has meddled with a problem
for which he is incompetent, and his criticisms on Dr. Woodward
appear to me utterly worthless.

The Council gave notice of their intention to propose the Count
Castracane for election as an Honorary Fellow of the Society.

The meeting was then adjourned to May 3. ~

Donations to the Library and Cabinet since March 1, 1876:

From

Nature. Weekly OE i tA tlh UR aM oad A AL ICN sae
Atheneum. Weekly Bh Mhefehd ASet RS | aeUS. SPPESE LEER Ditto.
SogiehysotpAnts iJ ounmelur yp st ssp tiawik sn itech wroshberaom lasses emepSOCtely/e
Journal of the Linnean Societ Ae Wee Ditto.
Transactions of the Watford Natural History Society .. : Ditto.
An Account of certain Organisms occurring in the Liquor

Sanguinis. By William Osler, M.D. .. . Author.
On the Pathology of Miner’s Lung By William Osler, M.D.: Ditto.
Le Diatomacée in Tunisia observate Dal Dot. Matteo Lanzi .. Ditto.
Structure and Development of Pareira Stem (Chondodendron

LOMENLOSU) Se OY, SORMIVMOSS = '5. se ace ee, an) sa) eae Ditto.
Popular Science Review.. No. 59) 2... ...8 2. ss.» + DPaditor.
Smithsonian Report, 1874 Ree hs Institution,
Istruzioni per chi Voglia Raccogliere ‘Di: atomee memoria ab

Francesco Castracane, WS) 9 Se Author.
Contribuzione alla Florula delle Diatomee del Mediterraneo ab

Mranecesco Castracanerl Gyo lc enc tose Male cet ene ens Ditto.
Three Slides of Minerals .. .... . F, Rutley, Esq.

C. 8. Bentley, Esq., and Philip J J. Butler, ae: were elected
Fellows of the Society.
Watter W. Reeves,
Assist.-Secretary,

Mepicat Microscoricant Society.

Friday, March 17, 1876.—Dr. F. Payne, President, in the chair.

Hints on the Systematic Study of Histology—Dr. Bathurst Wood-
man read a paper on this subject, one great object of it being to
recommend medical students and practitioners to study the micro-
scope broadly ; in other words, not to confine their studies to the
dead-house or the dissecting room, or to the medical uses of the
instrument, but to examine botanical specimens, furs, seaside objects,
anatomical and pathological specimens from the lower animals, and
in fact anything and everything they came across. Three or four
fresh objects a day would make nearly a thousand a year.

248 ! PROCEEDINGS OF SOCIETIES.

The next point was an earnest recommendation to make a sketch
or drawing (no matter how rough) of every object seen, either by the
camera lucida or otherwise, and to preserve these drawings.

Thirdly, to study micrometry. A cheap micrometer made by
ruling lines on paper was shown by the author, whose fourth recom-
mendation was, Work economically. Some cheap forms of apparatus
were mentioned in the paper. The use of low powers as a means of
training the eye, not to supersede, but to precede, high powers; and
the regular but systematic use of a few reagents were other matters
insisted upon in the paper. Dr. Woodman concluded by strongly
urging the formation of a library in connection with the Medical
Microscopical Society, for reference, and perhaps loan. Towards this
he would be happy to contribute a small sum, or some books, as a
nucleus. The desirability of such a library was almost self-evident,
since books on histology are for the most part either expensive, if
recent, or comparatively scarce and inaccessible.

The President regretted the too little general use of the micro-
scope, and that medical students had too little previous knowledge of
natural history ; and then—as in botany—high systematic work was
often commenced at once, and the smaller but equally important
plants neglected. Measuring and drawing he thought could not be
too much insisted upon, and he fervently wished that instrument
makers would provide a micrometer in lieu of much of the un-
necessary apparatus usually placed in microscope cases.

After some further remarks from various members, the meeting
resolved itself into a conversazione.

QvuEKETT MicroscopicaL Cuvus.

Ordinary Meeting, February 25, 1876.—T. Charters White, Esq.,
M.R.C.S., Vice-President, in the chair.

Mr. R. Packenham Williams described an improved form of
freezing microtome, consisting of a wooden chamber, to the bottom
of which is securely screwed a pillar with a spreading base and
curved sides; to the chamber is fitted a turned lid with a plate-glass
top, having a hole large enough to allow the end of the pillar to pass
through ; on the top of this pillar is placed the tissue in gum-water.
The lid is removed, and the cavity of the chamber surrounding the
pillar filled with ice and salt; the lid is then replaced, and in a
short time the tissue, together with the gum-water surrounding it, is
sufficiently frozen for making sections. The cutting is effected by a
straight-edged razor attached to a triangular frame, supported by
three screws ; a delicate adjustment is effected by means of the screw
at the apex of the triangle, instead of moving all the three screws, as
in the American instrument. Means are provided for placing the
razor parallel with the plate glass over which it moves, rendering
the instrument efficient and easily managed.

Ordinary Meeting, March 24, 1876.—Dr. Matthews, F.R.MS.,
President, in the chair.

Mr. N. E. Green made a further communication with reference to

PROCEEDINGS OF SOCIETIES. 249

his method of illumination by extremely oblique light, and exhibited
some specimens of Triceratium, in which the small disks at the angles
of the hexagons, usually seen as beads, were shown to be really
depressions or “ craters.”

Mr. M. Hawkins Johnson, F.G.S., read a paper “On Silicified
Structures in Pyritized Wood.’ A description was given of the
fossil wood-stems found, at low water, on the north coast of the Isle
of Sheppey, having been washed up out of the London clay. These
consist principally of iron pyrites, and are used in the manufacture
of sulphuric acid. On dissolving the iron pyrites by nitric acid,
acting upon a smooth section, the woody structure, which appears to
have become silicified, is left in relief. 'The conclusions drawn were
that the silicification was due to the replacement of the carbonaceous
walls of the wood-cells by silicon, and that the pyritous infiltration
subsequently filled the pores of the structure.

Mr. Charles Stewart, M.R.C.S., &c., at the invitation of the
President, gave a very interesting description of the hard parts of
Echinoderms, which he considered to rank amongst the most beautiful
objects claiming the attention of the microscopist. He enumerated
the various groups into which the class was divided, and described
their general characteristics. He then gave a detailed account of the
Echini, figuring the typical forms, and minutely describing their
anatomy, and the structure and arrangements of the spines, ambulacral
disks, and pedicellarie. Numerous specimens of the hard structures
of Echinoderms were exhibited under several microscopes in illustra-
tion of the subject.

ADELAIDE MicroscopicaL Cius, SoutH AUSTRALIA.*

The monthly meeting was held on August 20, 1875, Mr. Young in
the chair. Mr. Babbage exhibited objects for polariscope. Dr. Whittell
exhibited a thin section of a cancer of breast removed four weeks ago.
The section had been cut so as to include a portion of the adipose
tissue, and the interest of the preparation lay in the fact that the can-
cerous cells were just beginning to invade the fatty tissue. It was
determined to hold a conversazione in September or early in October.
Several members promised to assist, and it was recommended that, as
far as possible, the members exhibit objects prepared by themselves,
and of local interest. The Chairman then gave a short address on
Pond-life, which he illustrated by objects brought from ponds near
his residence. He said these would have been more numerous, but
he found the season was not so far advanced as in former years, and
many confervoid growths had not yet made their appearance. Among
the objects of interest were several specimens of the Desmidiacee,
a beautiful specimen of Volvox resembling the Volvow globator of
England, but differing from it in a few minor details. A specimen
of Nitella in which the circulation could be distinctly seen was also
exhibited. This attracted the attention of members because many
of them had failed to find in South Australia a plant in which the

* Report supplied by Dr. Whittell.

250 PROCEEDINGS OF SOCIETIES.

circulation could be clearly observed. After the Chairman’s address
a few minutes were spent in comparing the scales of the Lepisma
found in Australian houses with those of the Lepisma saccharina.
The Australian Lepisma is commonly known as the silver eel, and is
about an inch long. The scales are of precisely the same form and
structure as those from England, but are from two to three times
their size, and the markings on them are much more distinct.

The monthly meeting was held on September 17, 1875,
Mr. T. D. Smeaton in the chair.

It was decided to hold a conversazione during October, instead
of the usual monthly meeting. Several gentlemen promised to lend
their assistance.

Mr. G. Francis exhibited crystals of aphidine, a fat he had
succeeded in extracting from the Aphis. This when melted on a hot
slide and allowed to cool formed a beautiful polariscopic object.
Mr. Francis also exhibited diatoms from Turkey sponge, and a
‘* Polar clock.”

Mr. Young exhibited specimens of Floscularia.

The Chairman then gave a short address on the Polyzoa, dwelling
chiefly on their characteristics and classification of such as are found
along the South Australian coast. Numerous specimens were ex-
hibited ; amongst these were several varieties of Catenicella. The
Chairman said he had met with at least ten varieties on the Australian
coast.

The first public soirée given by this club was held on the evening
of November 6, 1875, in the rooms of the Institute, which were
kindly lent for the occasion. His Excellency Sir A. Musgrave,
Governor-in-Chief, Lady Musgrave, several members of the ministry,
and a large company of ladies and gentlemen, honoured the club with
their presence, and manifested great interest in the instruments and
objects placed on the tables for their inspection. The following is
the list of exhibits :—Rev. J. Jefferis: Smith and Beck’s binocular,
with Darker’s triple selenites ; Field’s dissecting and mounting micro-
scope ; and Highley’s field microscope. Tissue and spicules of sponge
(South Australian) ; skin and spicules of holothuria (Northern Terri-
tory Trepang).—Dr. Whittell: Powell and Lealand’s large micro-
scope, with binocular prism for high powers; Beck’s large binocular ;
Nachet’s portable microscope ; Highley’s hospital microscope. Im-
mersion objectives: Powell and Lealand’s j}; inch; Carl Zeiss’s
gy inch; Moller’s Probe-Platte; and suitable test-objects. Eye of
beetle, showing through each of its lenses a separate image of the
seconds’ hand of a watch in motion; poison fang and duct of centi-
pede (to illustrate new mode of preparing insect structures) ; anato-
mical and pathological specimens— muscular fibre; hard cancer,
showing its earliest stage; epithelial cancer; glioma; Trichophyton
tonsurans (from ringworm in scalp); scales of lepisma (Australian
“silver eel”), shown by Wenham’s method of reflex illumination.—
Dr. Gardner: Beck’s student’s microscope; Moéller’s Diatomaceen
Typen-Platte, containing 409 different diatoms, arranged in order in

PROCEEDINGS OF SOCIETIES. 251

a space of less than + inch square.—Mr. B. H. Babbage: Monocular
microscope, with Collins’ objectives. Crystals of salt; sulphates of
iron, nickel, cobalt, copper, zinc, potash, and magnesia; acetate,
nitrate, and superoxalate of potash ; iodide of potassium: borate and
muriate of soda; muriate of ammonia; alum; sugar ; citric, tartaric,
and oxalic acids.—Mr. Mais: Collins’ Al Harley binocular, with
circular goniometer stage, revolving sub-stage, with centering adjust-
ments; immersion lens, j'5 inch; Webster’s achromatic condenser ;
Brown’s iris diaphragm; Abraham’s achromatic prism ; Maltwood’s
finder ; Darker’s revolving selenites ; Jackson’s micrometer eye-piece ;
and other fittings. In Blackwood cabinet of colonial manufacture.
Fiddian’s lamp; Horne and Thornthwaite’s mounting table. Polarizing
objects; salts of quinine ; starch from Calabar bean; embryo oysters ;
human skin; plaited horsehair; gun-cotton muslin; mummy cloth ;
whisker of lioness; palates of whelk, limpet, snail, chiton, and ear-
shell; gizzard of cricket. Modller’s Diatomaceen Typen-Platte, No. 2;
elaborate groups of diatoms, transparent and opaque.—Mr. G. Francis :
Smith and Beck’s educational; Browning’s spectroscope ; micro-spec-
troscope ; direct-vision spectroscope. Tubes of fluids, showing ab-
sorption bands—didymium; uranium; cobalt; blood; chlorophyll ;
aniline dyes ; cineraria ; indigo; bile pigment; fish pigment. Metals
in combustion, showing bright lmes—potassium ; sodium ; lithium ;
thallium; barium; strontian; calcium; indium; cesium; rubidium.
Absorption bands of selenite under polarized light.—Mr. J. R.
Gurner: Powell and Lealand’s monocular; Hartnack and Ober-
hauser’s monocular. Insects and insect structures found on the
Eucalyptus.—Mr. J. G. Young: Harley’s binocular, by Collins, with
sliding objectives. Botanical specimens: cuticle of wheat, oats, &c. ;
spiral vessels; raphides; hairs of leaves; leaf of sphagnum; seed of
Paulownia imperialis ; seaweed.—Mr. C. W. Babbage: Smith, Beck,
and Beck’s binocular. Wings of butterflies; hairs of elephant,
mouse, rat, human hair; feathers of humming-bird, goldfinch; wing-
cases of diamond beetles ; skin of sole; scales of eel, sole-—Mr. Calf :
Beck’s popular binocular, with Webster's condenser and Collins’
parabolic reflector. Insect preparations: proboscis of butterfly,
drone-fly, and blow-fly ; antennz of moth and blow-fly ; foot of tabanus,
blow-fly, and spider ; wing of house-fly, mosquito, and lace-wing fly ;
epidermis of beetle; oar of water-boatman.—Mr. Holmes: Crouch’s
student’s histological monocular, with glass revolving stage. Poly-
cystina ; foraminifera ; micro-photographs ; sections of sugar-cane,
gutta-percha, birch, lemon, Monstera deliciosa ; sori of ferns ; leaves;
pollen; young oysters in situu—Mr. Smeaton: Smith and Beck’s
_ popular binocular. Diatoms from ‘ Challenger’; parasites of native
companion, canary, pheasant, bat, horse, pig; South Australian
polyzoa, as opaque objects and by polarized light; blood-disks from
mammals, reptiles, and fish; wings of South Australian butterflies
and moths.

252 PROCEEDINGS OF SOCIETIES.

San Francisco Microscorican Soctery.

Annual Meeting, February 3, 1876.—Election of officers resulted
in the re-election of the old board of management, as follows :—Pre-
sident, Wm. Ashburner (who delivered an excellent address on the
work done by the Society, and who deprecated the notion of publishing
‘ Transactions, in the present state of the Society); Vice-President,
Henry C. Hyde; Corresponding Secretary, Charles W. Banks ; Re-
cording Secretary, C. Mason Kinne ; Treasurer, Charles G. Ewing.

Mr. Arthur Cottam read a paper upon a new Aulacodiscus, which
had been brought from the west coast of Africa by Mr. Martin, an
officer of H.M.S. ‘Spiteful.’ It had been considered to be a variety
either of A. Kittoni or A. Johnsoni ; and after describing the charac-
teristic features of each of these species and of the new diatom,
Mr. Cottam expressed an opinion that the new form was in some
respects so distinct from either, that it might well be made a distinct
species, for which he suggested the name of Aulacodiscus Africanus.

Mr. N. E. Green read a paper upon a new stage arrangement for
the examination of objects either by reflected or transmitted light,
and exhibited a slide of P. angulatum under a ;';th by Zeiss, illu-
minated entirely by side light. The silvery appearance of the object,
contrasted with the grey background, was very beautiful, and the
definition extremely sharp. Mr. Green also remarked upon the
advantages of side illumination in the observation of the surface
markings of diatoms; and exhibited Triceratium and Isthmia under a
yisth by the limelight, as examples of very oblique reflected illu-
mination.

Fatrmount MicroscopicaL Sociery oF PHILADELPHIA.

The regular monthly meeting was held May 20, in West Green
Street. The subject of the evening was Micro-fungi. The Secretary,
Mr. Stevenson, read a paper on the subject, and illustrated it with a
series of slides of ecidium, puccinia, aregma, triphrogmium, uredo,
ustilago, tuchobasis, &e. Drs. Griffith and Shakespeare opened a
very interesting debate on the subject of “the fungoid origin of
disease,” which was freely discussed by Dr. James, Mr. Gray, and the
other members present. The evening was spent very profitably to
those present, and was pronounced by all to be one of the most enjoy-
able held during the year. A vote of thanks was unanimously tendered
Mr. D. 8. Holman for his fine exhibition of the gas microscope at the
meeting in February.

This Society grows in interest and numbers, and is fast becoming ,
a permanent organization.

3 Af

Monthly Macroscopical Journal, Junel 1876 Pl .CXXXIX.

Gnats Body Scale

from a drawing by

—s Dr. Anthony

A. Grats Body Scale
from a photograph by
Dr. Woodward. 1350

=e —— * <= ts :

ibs oe bye
Seeded os
SHUM SELENE SAS seats o — =

= —s
ee chil anal
alan i ae
SAMMI ae
— z G. ta
ee AER a
Beye Tek t: METS Cee anee eee yet oe ma
Sipe. _— moro d ee
itebilarity ee

W West & C° imp.

Sp resenrsstrr
raiSbeasances

Mosquito Sca

Bros 2 photogr ath

by D? Woodward.

eee

THE

MONTHLY MICROSCOPICAL JOURNAL.

JUNE 1, 1876.

I.—On the Markings of the Body-scale of the English Gnat and
the American Mosquito.

By Dr. J. J. Woopwarp, U. 8. Army.
(Read before the Roya Microscorican Society, May 3, 1876.)
Puates CXXXIX. anp CXL.

My attention was first directed to the markings on the body-scales
of the English gnat bya letter received last summer from Mr. John
Mayall, jun., enclosing a mounted slide of these scales, and a photo-
graph of a drawing of one of them by Dr. John Anthony, of Bir-
mingham, representing the scale as marked by longitudinal beaded
ribs, having three uniform parallel rows of smaller beads in every
interspace between two adjoining ribs. (See Pl. CXXXIX.)

Mr. Mayall stated that Dr. Anthony had made the drawing to
represent an appearance of the scale glimpsed by central light, but
had not been able to show this appearance to him in the microscope
as definitely as it appears in the drawing, and requested me to
undertake to photograph the scale as seen under the microscope.
This I did at such leisure hours as I was able to command during
the latter part of last year, and in so doing arrived at results which
may perhaps be of interest to some of your Fellows.

I at once observed the very great similarity between the scales
of the English gnat and those of the American mosquito, with
which I had been familiar for a number of years; a similarity
which relates to all the details of surface markings, as well as
to the size and general outlines of the scales. In the case of the
mosquito, I had seen that the scales are crossed transversely by fine
markings, probably ridge-like corrugations of the thin double mem-
brane composing them, and that these transverse markings crossing
the longitudinal ribs at recular intervals, gave to the latter a beaded
appearance; but I had not believed that the transverse markings
were also beaded. I must add that the ribs and transverse mark-
ings exist on both surfaces of the scale, though much more boldly
on one than on the other, and that the longitudinal ribs of the
opposite sides unite at the broad end of the scale, where they
generally project as bristle-like appendages beyond the general
contour.

My examination of the slide received from Mr. Mayall has led

VOL. XV. i

254 Transactions of the Royal Microseopical Society.

me to the opinion that this description applies to the gnat scale as
well as to the mosquito. Nevertheless, on examining a gnat scale,
as requested by the donor of the slide, with the immersion y¢th of
Powell and Lealand, by central illumination, I succeeded, after
some trying with the right-angled screws of the achromatic con-
denser, in obtaining, as I suppose, the very appearance Dr.
Anthony’s drawing is intended to represent, and the three parallel
rows of minute intereostal beads started out suddenly into view
between each pair of longitudinal ribs over the whole surface of
the scale.

This appearance was so realistic that at first I clined to the
opinion that it represented truly the actual markings of the scale,
and accordingly I endeavoured to photograph it as requested, with
the objective named, by monochromatic sunlight, and after several
failures succeeded in obtaining a fair representation of what I saw.
I send herewith a print (marked A) from the resulting negative.

I have, however, since then been led to form the opinion that
these clearly seen beads are a spurious appearance, produced by
longitudinal diffraction lines, conditioned by the longitudinal ribs
and parallel to them, which cross the true transverse markings
at right angles, and thus give rise to the optical appearance of
beads at the point of intersection ; the whole series of phenomena
being similar in character and origin to the diffraction phenomena
observable in many diatoms, &c., as described by me in my “ Note
on the Markings of Frustulia Saxonica ” in this Journal, December
1875, p. 274.

My chief reasons for this opinion in the present case are—
firstly, that the longitudinal diffraction lines are clearly seen, both
in the microscope illuminated by lamp or sunlight, and in the
photographs (as, for example, in the print A) to extend into empty
space beyond the contour of the scales almost as far as the ends of
the bristles in which the parallel ribs terminate; and secondly, that
they vary in number with varying obliquity of illumination, so that
in the same scale two, three, four, or five rows of beads can be seen,
and photographed at pleasure, in each intercostal space.

Since arriving at this conclusion I have had no difficulty in
producing at will, either the beaded appearance, or that which I
conceive to represent correctly the surface markings, on any scale
I have tried, whether of the gnat or mosquito.

If the selected scale is illuminated with the light thrown per-
pendicularly to the transverse markings, by means of an Abraham’s
prism, the beaded ribs and smooth transverse markings will be
clearly shown ; and if now the stage be rotated so as to turn the
long diameter of the scale more and more obliquely to the illumi-
nating pencil, the spurious lines, and with them the beads, will!
start into view; the number of spurious lines, and consequently

Markings of the English Gnat, &c. By Dr. Woodward. 255

the number of rows of beads, varying with the angle of the illumi-
nating pencil. Or the true appearance may be produced by the
achromatic condenser adjusted so that the light is either truly
central, or slightly oblique in the direction of the length of the
scale ; and then a very moderate degree of obliquity in the illumina-
tion transversely to the scale, obtained by means of the right-angled
screws of the condenser, will bring out the rows of beads, varying
in number as in the former case, in accordance with the degree of
obliquity attained.

I submit these results without further comment at the present
time, with a few additional photographs intended to represent some
of the chief appearances obtained. ‘Two of these pictures, in addi-
tion to that mentioned above, are from the slide of gnat scales sent
by Mr. Mayall, and are taken with the immersion 7gth of Powell
and Lealand ; the others represent a mosquito scale as seen with an
immersion sth, constructed for the Museum by Mr. Tolles, of
Boston. I selected for this series a different lens from that used
for the gnat scales to show that the diffraction appearances dis-
cussed in this paper result from the optical conditions under which
the scales are viewed, and not from any peculiarity in the objectives
of any particular maker. |

In conclusion, I would refer those who desire preliminary
information as to the character and distribution of the gnat scales
to the paper by Mr. Jabez Hogg, “On Gnat Scales,’ in this
Journal for October, 1871, p. 192; or to his work on the Micro-
scope, the first edition of which was published in 1854. The
description there given of the various forms of gnat scales, and of
their distribution on the insect, is very nearly accurate for the
mosquito also.

List of Photographs.

A.—Gnat scale, showing three rows of intercostal beads. Magnified 1350 dia-
meters by Powell and Lealand’s immersion ~;th. (Neg. 771.) See Pl.
CXXXIX., Fig. A.

B.—A_ smaller gnat scale, showing smooth transverse markings. Magnified
1500 diameters; same objective. Achromatic condenser; central light.
(Neg. 781.) See id., Fig. B.

C.—The same scale, with same objective and power, but moderate obliquity of
illumination obtained by means of the right-angled screws of the con-
denser. (Neg. 782.) See id., Fig. C.

D.—Mosquito scale, showing smooth transverse markings. Magnified 1350 dia-
meters by an immersion {th of Tolles. Achromatic condenser; nearly
central light. (Neg. 765.) See Pl. CXL., Fig. D.

E.—Same scale, same objective, but light oblique laterally as well as trans-
versely, showing two rows of beads in each intercostal space. 1350 dia-
meters. (Neg. 768.) See id., Fig. E.

F.—Same scale, &e., showing three rows of beads in each intercostal space.
1300 diameters. (Neg. 778.) See id., Fig. F.

G,.—Same scale, &c., showing four rows of beads in each intercostal space.
1350 diameters. (Neg. 766.) See id., Fig. G.

Tt 2

256 Transactions of the Royal Microscopical Society.

Note by John Anthony, M.D.

Having read Dr. Woodward's paper on the gnat and mosquito
scales, and looked carefully at the set of photographs in illustration,
which that gentleman has had the kind courtesy to forward to me,
I can come to no other conclusion but that what I have hitherto
regarded as real bead markings on the membrane in the intercostal
spaces on the scales from the body of the gnat are really and truly
spurious Images, or, in the words of Dr. Woodward, “ diffraction
appearances.’

Some two years ago, in the examination of a large number
of gnat scales, principally with the fine }th and y¢th objectives of
Messrs. Powell and Lealand, such results were ‘erat that I
thought I had found in the scale from the bods y of the gnat an
excellent test for the “ definition” of high-power objectives, inas-
much as there seemed, with moderately oblique and well-corrected
light, what appeared to me triple rows of clearly defined beads
between the beaded longitudinal ribs of the scale ; and, as the same
appearances of beads were always manifest, and as those beads
always seemed to come out clearer when viewed with objectives
of well-known excellence, I trust to be pardoned for believing that
what I saw were not only real appearances, but that such objects as
the gnat scales might be of the greatest service to the microscopist
as tests for the defining qualities of high-power objectives. Under
such impression I made a careful drawing of the markings on the
gnat’s scale under the most favourable conditions, and that drawing
I copied by means of photography; the photograph would have
been made directly from the scale of the gnat itself, but I had no
heliostat. These photographic copies of the drawing have gradually
passed into the hands of one or other of my microscopical friends
until the specimen forwarded with this paper is the only one left
to me. However, I have the negative, and if possible impressions
shall be printed for distribution among the members present at the
next meeting of the Society.* (Pl. CXXXIX.)

Taking the H, F, and G photographs of Dr. Woodward to be
the most characteristic, inasmuch as they show respectively two,
three, and four rows of beads as seeming to exist upon the same
scale under different conditions of illumination, I think one can
only look upon my drawing as a representation of very clearly seen
spurious beads. Of course it is not very flattering to one’s amour
propre to have it shown so convincingly that one has taken the
shadow for the substance ; but I am assured that I shall have erred
in good company, inasmuch as the analysis of these diffraction
images will strike at the root of a vast number of descriptions of

* Some were sent by Dr. Anthony to the meeting.

Markings of the English Gnat, &e. By Dr. Woodward. 257

quasi beaded tissue seen in all sorts of objects examined with high-
power lenses.

This brings me naturally to the observation that I think micro-
scopists, who are not too proud to learn, owe to Dr. Woodward a
debt of gratitude for the trouble he has taken, and the skill he has
displayed, in teaching us the precautions we ought to take in high-
power investigations to distinguish between the false and the true.
I have worked long enough at the microscope to feel that as a rule
one ought, like the late Lord Eldon, to “doubt ” everything; and
have often amused myself in producing, on well-known diatoms, a
series of permutations of “diffraction phenomena,” and therefore
can appreciate most fully the truthful excellence of Dr. Woodward’s
article and illustrations in the December number of the ‘ Micro-
scopical Journal.’ I regard these papers on spurious appearances as
among the most valuable contributions to microscopical literature.
Dr. Woodward points out that detail, however clearly seen upon a
scale, may be more than suspected of being unreal if it seems not to
be confined to the limits of the scale or shell itself, but to “ pass
off into space.” A question arises as to how you are to deal with
the appearances, such as a fairly careful observer might get, and
such as I myself observed on the gnat’s scale, where there was no
projection of the image into space; a phenomenon with which, as 1
stated, I am very familiar. The only suspicious point noticed
was an apparent alteration in the character of the detail on revo-
lution of the object, but the employment of light more or less
oblique has in most cases, and particularly in very diaphanous
objects, accustomed one to look at certain scales.always m the
same position with respect to the plane of the illumination as being
“best seen”; and it is to be feared that very many of us, in our
employment of the microscope, are apt to be led away by beauty
of image.

It appears to be clear that no perfection of “condenser,” and no
superior quality in the objective, can save us from acquiring erro-
neous impressions of what we see in the microscope, if we have not
a very distinct notion of the “ pitfalls” which await us in the shape
of diffraction images. Dr. Woodward evidently has grasped this
difficult subject with a master hand; he has used photography as a
witness—which to me is most satisfactory ; he has given us a most
valuable lesson, and I for one beg to thank him for it.

Wasuwoop Hratu, BrrMincHAm,
April 3, 1876.

258 Transactions of the Royal Microscopical Society.

I.— Notes on Micro-photography.

By Surgeon-Major Epwarp J. Gaver, H.M. Indian Army, now
Professor of Surgery, Medical College, Calcutta.

(Read before the Royvau Micrescortcan Sociery, May 3, 1876.)
Puates CXLI. anp CXLIL

Tae best micro-photographs can of course only be produced by
the best objectives ; but besides this many things are required, and
as much as anything else, good manipulation. You may have a
very good light and the most perfect form of apparatus, and yet,
from want of sufficient control over all, really good work may not
be the result of the expenditure of much labour and time. It is
manifest that the best position for the operator during the whole
manipulative process (except of course the photographic part of
it) is near the microscope condenser, mirror and source of light,
and not far away from all this apparatus at the focussing screen
and dark slide. To be able to stand in a comfortable position
within easy reach of your microscope and the other apparatus, and
to be able to view your focussing screen and sensitive plate, watch-
ing the light, and altering it if you wish it at any time during the
process, affords great facility to the worker. All this can be readily
accomplished by the use of a small telescope, and with its help a
very small quantity of special apparatus is required. The writer
has worked for many years with the form of apparatus figured in
Pl. CXLI., which consists of a common, heavy, strong table A,
about 12 feet long and 2 feet wide. At one end of this table the
mirror D is placed near enough to the source of light B and the
cell for cutting off heat rays C, to allow of all being easily
reached even when the eye is applied to the telescope N. The
condenser E, the microscope F, with its condenser H, its object-
glass G, its stage and fine and coarse adjustments, are all close
together within easy reach of both hands all through the pro-
cess. The focussing screen L and dark slide are at the other end
of the table, and are made movable so as to slide up and down on the
ledge O, in order that the distance between them and the micro-

EXPLANATION OF PLATE CXLI.

A. Strong heavy table. | I. Mirror of microscope turned aside.
B. Round hole for light. | J. Cone connecting microscope with
C. Cell for abstracting heat rays. camera.

D. Mirror and stand. K. Camera.

E. Condenser and stand. L. Dark slide. we

F. Microscope. | M. Piece of thick white cardboard.

G. Object-glass. | N. Telescope.

H. Achromatic condenser of micro- | O. Slide for back of camera,

scope. | P,P. Diaphragms.

The Monthly Microscopical dournal,dune 1.1876. PLOXLI

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Notes on Miero-photography. By Edward J. Gayer. 259

scope may be altered at pleasure. The mode of procedure is as
follows. Uncover the round hole B, the source of light (if sun-
light is used, this hole, together with the rest of the apparatus
attached to it, should have a vertical movement to allow for the
changing position of the sun), and place in front of it either an
ammonio-sulphate of copper or alum cell, or a piece of blue glass,
according to the work you are going to do. Adjust the mirror D, which
is best made of silvered glass with the polished silvered side up, and
connected with a ball-and-socket joint to a firm but movable stand
on the table. Place the large condenser in the path of the rays as
close to the mirror as may be convenient, and at such a distance
from the microscope that the rays of light shall cross before enter-
ing the achromatic condenser of the microscope. This large con-
denser EK should be an achromatic lens, of moderate focus, and as
large as possible, not less than 3 inches in diameter, and not more
than 10 or 12 inches focus. A photographic landscape lens
answers well. Adjust the achromatic condenser of your microscope,
the object, stage, and objective. Place your dark slide open in the
holder at the other end of the table with an unprepared plate
in it, on which you have previously evenly pasted a piece of white
albumenized paper, and on which you have drawn two diagonal
lines from corner to corner of the plate, in order to show its centre,
and on which at the centre you have either neatly written or
pasted a word in small type. Adjust your telescope N so as to
view this word in perfect focus, and then leave it so. This tele-
scope is best made out of the object-glass of a large opera-glass
and the eye-pieces of your microscope, by connecting the two with
tubes of sufficient length to allow of considerable throwing back of
the conjugate focus of the object-glass, a necessary result of your
viewing the plate at a distance of a few feet and your telescope
object-glass receiving divergent instead of parallel rays. Then still
looking through the telescope, which is a fixture, being made to
slide stiffly through a hole in the fixed front of the camera K,
focus with the fine and coarse adjustments of your microscope, and
bring the object into its proper place on the screen of albumenized
paper, the centre of which is abundantly apparent owing to the
word and the cross lines, and is a very easy substance to focus on.
Having made all adjustments, remove your dark slide with the
focussing screen in it, shut the hole B by a shutter from outside
the window worked by cords. Prepare your sensitive photographic
plate, with which you replace the plate covered with albumenized
paper, and put the closed dark slide into the place where you took it
from, and put a piece of white cardboard M into the groove close in
front of the dark slide; open the shutter and arrange the light finally
on the cardboard. Place a book or other shield in front of the
large condenser E in the path of the rays, so as to shut off the

260 Transactions of the Royal Microscopical Society.

light ; remove the cardboard M, lift the shutter of the dark slide
and expose the plate, watching the process through the telescope,
and if the exposure isa long one altering anything that may appear
necessary, for many beautiful results may be obtained at this stage
of the proceedings by altering the light during the exposure. For
instance, to mention one which will be at once self-obvious, an
object can be exposed first as an opaque specimen and then as a
transparent one on the same part of the plate, thus bringing out
the surface markings as well as the transparent outlines. The
microscope tube and the eye-pieces may be used with the telescope
as they should never be used with the microscope in micro-photo-
graphy as they contract the field and blur the image, magnifying
power being better obtained by distance, which with this apparatus
may be anything from 2 feet to 8 feet or more if the table is made
long enough. ‘The microscope should be connected to the camera
by a cone J, which may be made of tin, paper, or any suitable
material. The camera is best made quite open, as shown in the
Plate, a cloth being thrown over it supported by the ends and the
diaphragms P, P, which are very useful to cut off light not required
to form the picture. They should be so arranged as not to inter-
fere with the telescope, and may have holes cut in them for this
purpose if necessary. A sufficiently strong eye-piece should be
used in the telescope to give a clear view of the minutiz of the
specimen, so that a very perfect focus may be obtained. Your
hands are the best heliostat, as the mirror is within your easy
reach the whole time. Instantaneous micro-photography should
be attempted with no objective of a higher power than half an inch,
and the large condenser only should be used. ‘The alum or other
cell should also be removed at the time of exposure. A special
shutter will also be required between the large condenser and the
object to be photographed. This shutter should have no connection
with the table, as it would communicate a vibration to the whole of
the apparatus at the moment when everything should be perfectly
still except the movements of the animalcule you wish to photo-
graph. A good shutter for this purpose can be made with two
boards having round holes cut in them and made to slide one over
the other, an india-rubber band being the motive power. In
this way one hole may be made to pass the other with such speed
that the exposure is absolutely instantaneous, and the portraiture
of rapidly moving subjects rendered perfectly easy with a good light.
The writer has done many in this way.* When the higher objec-
tives are used, such as the ;',th, they are generally better used on
the immersion principle, and glycerine or oil of cassia may be used
instead of water. When substances with a higher refractive index

* Copies of some of these instantancous micro-photographs may be seen in
the Indian Museum, London.

Notes on Micro-photography. By Edward J. Gayer. 261

than water are used, the focal distance between the objective and the
glass cover will be increased, and the screw-collar must be adjusted
accordingly to suit the more refractive medium in which the objec-
tive has been immersed. When oil of cassia is used (the substance
chiefly used by the writer), which has a refractive index as high as
1-405, the screw-collar should be used so as to close the combina-
tion completely ; with this latter substance it will be found quite
possible to focus through rather thick covering glass. The view I
- have obtained, with the help of the oil of cassia, of various objects
has been very satisfactory. Both the longitudinal as well as the
transverse strie on Frustulia Saxonica may be made out fairly.
(Pl. CXLIL.) The longitudinal strize are at the same distance
apart as the transverse. I think, from the help I have obtained
in this way, and from various experiments I have made, that the
markings on at least most of the diatoms are neither elevations or
depressions, but are holes, the line of fracture always passing
through these holes in the same way as it does through the per-
forations round a postage stamp. Diffraction and interference
phenomena are so deceiving and perplexing, and look so real, that
even photographic proof, as it is sometimes called, goes for very
little ; but I hope on some future occasion to be able to offer
satisfactory proofs of the statements I have here made, and regret
much that press of time prevents my doing so now.

262 Transactions of the Royal Microscopical Society.

IIL.—On Renulina Sorbyana. By J. F. Buaxu, F.GS.
(Read before the Roya Microscoricat Socrety, May 3, 1876.)

Twenty years ago Mr. Sorby noticed some remarkable bodies in
the lower calcareous grit of Scarborough, which he described in a
paper read before the Geological Society. These bodies were for the
most part agatized, as are most of the shells in the same deposit.
He described them as reniform viewed on the side, and oval as seen
behind, their size being on the average 53> inch. In spite of their
metamorphosed state, some gave signs of having been originally
hollow, because a line of dirt parallel to the outside surface could
be traced within. He sums up his observations thus: ‘These
facts, I think, indicate that these bodies were small shells. ... .
Nevertheless, I will not insist on this view, for I have found cases
where the impurities were not arranged as if there had been a shell,
though not in a manner irreconcilable with that supposition... .
They may perhaps have been Foraminifera, although I have not
been able to detect any internal divisions into chambers, nor any-
thing to indicate that they are detached foraminiferous cells.”

Since that time no such bodies have been observed elsewhere,
and no further light has been thrown upon their nature.

On examining the washings from some rubbly clay beds asso-
ciated with pisolite occurring at Sturminster Newton, in Dorsetshire,
near the base of a series of strata representing the coralline oolite
in time, and a little more recent than the lower calcareous grit of
Scarborough, I was surprised to find the material crowded with
such minute reniform bodies, which a comparison with Mr. Sorby’s
description and afterwards with his specimens themselves, left no

Renulina Sorbyana x 100 diam.

Fig. 1.—View from behind.

2.—Side view of a specimen, showing in parts an outer layer on the surface
with areolate ornament.

»» 3.—Side view of another, in which small perforations of the shell appear.

» 4—A broken specimen, showing the shells are hollow.

”

On Renulina Sorbyana. By J. F. Blake. 263

doubt of their being the same. These new examples settled one
question with certainty. ‘There could be no longer any doubt
that they were originally hollow, for these were easily broken by
pressure, and then presented their two empty halves, like a broken
egg-shell, as plainly as possible.

Another point less doubtful before was also proved, namely,
that they had been originally calcareous, because these are so.
Silex may replace carbonate of lime, as it had done in the specimens
from Filey, but the process cannot well be reversed. I conclude
therefore that these Sturminster specimens are in their original
condition. Acidulated water appears, however, to have had access to
them, as their surfaces are eaten away and more or less rugged.
This perhaps suggested the idea which my friend Professor Rupert
Jones kindly favoured me with, that if Foraminifera, they might
belong to the Saccanuvina group. ‘Treated with hydrochloric acid,
they certainly leave a small residue, which, however, appears to be
structural silex and not grains of sand. The presence of such a
residue would certainly not prove them to be arenaceous Foramini-
fera, for the undoubted Dentalines, Marginulines, &c., of the same
deposit also leave a small residue, while the true arenaceous forms
are almost if not entirely untouched. I have been fortunate,
however, in being able to obtain what I think to be further evidence
of their structure and nature. In a deposit of clay at Hilmarton,
near Calne, Wilts, belonging to the uppermost portion of the
corallian beds, and therefore of very similar age to the former
deposit, I found a few among the ordinary Foraminifera of the
washing which appear to have undergone but little change. These,
however, do not make up the bulk of the microzoan fauna as at
Sturminster and Scarborough, but are rare im comparison. Like the
others, they are hollow and dissolve in hydrochloric acid, but their
surface is less destroyed. As they now are, they appear to have
two layers, an external one more opaque, which is mostly broken
away, and an internal one more transparent. The external coat
appears to me not to belong to the original shell, but to be a sub-
sequent deposit. However, in some it presents in places an areo-
_lated structure, that is to say, is dotted over quincuncially by little
pits. ‘The internal layer shows, as I think, a foraminated structure
like the shells of Rotalines ; but as the appearance is by no means
distinct and cannot often be seen, I confess it might be more satis-
factorily demonstrated. In some these foramina seem to be limited
to the neighbourhood of certain lines forming a pattern on the
shell, and not to be uniformly scattered over the surface. The areo-
lation of the external layer when present is more certain, and m
idea of its meaning is that the calcareous matter has collected
on the interspaces between the true foramina below, making these
latter more conspicuous, though in some places it has covered foramina

264 Transactions of the Royal Microscopical Society.

and all. If I have rightly interpreted the appearances to indicate
foramina at all, then of course the nature of these bodies is settled.
What else can the appearances be due to? ‘The action of polarized
light has something to say about this. Seen in this way, the shell
is divided into a number of compartments separated by irregular
lines. These lines, then, seem to be cracks, or the boundaries of
irregular crystallization ; at least there is nothing in the appearances
to prove they are not, and the whole shell seems so altered by meta-
morphic crystallization as to render it doubtful how far any speci-
men shows the original structure. One specimen, in which the
whole interior was filled with black dust, showed little perforations
of the shell, but they were so irregular and of such various sizes
as to make it as likely as not they were due to metamorphism
rather than structure. We are therefore cautioned that anything
but what cannot possibly be other than true structure may possibly
be due to some subsequent alterations, and therefore be deceptive.
Nevertheless, their behaviour under polarized light is very similar
to that of Foraminifera, and it would be, I think, difficult to prove
most of the fossil Foraminifera such by the demonstration of their
foramina, only we do not attempt it because we recognize them by
their shape.

In the present case we do not recognize the shape, but there
is nothing in it to prevent their being Foraminifera. They
have only one cell, no partition occurring inside. ‘They have no
large aperture, but neither has the Orbulina or the Globigerina in the
majority of cases. The general resemblance, in fact, of these shells
in point of structure to that represented by the fossil Orbulinz in
similar strata, inclines me strongly to the belief that the foramini-
feral interpretation is the right one, that they belong to the per-
forate group, and should be placed near the last-named genus.
They have a general resemblance in shape to the Noctiluca, and
the lines on their surface which are distinguishable in most, if they
be not due to crystallization renders the similarity greater; but
besides this, no organism that I can think of gives any example of
such a form.

I take them, therefore, to be a peculiar form of Foraminifer, _

very characteristic of corallian strata, and would propose to name
them Renulina from their shape, and for a specific name Sorbyana
from their original discoverer.

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“2 Ket

( 265 )

1V.—Remarks on Frustulia Saxonica, Navicula rhomboides, and
Navicula crassinervis. By Cuartes Stopper, U.S.A.

(Read before the Roya Microscoricat Socrery, May 3, 1876.)

As there seems to be much uncertainty prevailing in regard to the
three species named above, I will attempt to clear the matter up.
To do this it is needful to refer to the original descriptions, aided
by the light of the most recent classification. Ralfs—Pritchard’s
‘Infusoria,’ p. 924, 1862—gives the generic character of Frustulia
(Ag.), “ Bacillar immersed in an amorphous gelatinous substance ; ”
fF. torfacea (Braun), “ Rhomboid lanceolate, with obtuse apices,
stout median rib, and small central nodule ;” F. Saxonica, “Slen-
derer than I’. torfacea, valves more acute, front view linear, with
broadly rounded ends.” ‘These are unquestionably the original
descriptions of the authors. But Professor H. L. Smith (thaw
whom there is no better living authority), “ Conspectus of the
Families and Genera of the Diatomacez,” ‘The Lens,’ Chicago,
1872, rejects as a generic distinction the mode of growth, and con-
sequently the whole genus Frustulia. Except the mode of growth
there is no one character or combination of characters to distin-
guish Frustulia from Navicula. Mr. Hickie, this Journal, p. 127,
No. lxxxvu., confesses “ that he is unable to state where Frustulia
Saaonica ends and our small rhomboides begins.” In this he only
confirms what diatomists have known for the last ten years. Now
what is NV. crass.?- Wim. Smith, ‘ British Diatomacez,’ 1852, gives
N. crassinervia Breb., “ Valve elliptic lanceolate, extremities pro-
duced, strize obscure, length -0013" to -0026".” N. rhombordes,
Ehr., “V. nearly quadrangular, strize very faint parallel, -85”
to :001"."* There is nothing to distinguish one from the other,
except the produced extremities of N. crass. Now that is such a
trivial distinction, so far within all known and all but universally
acknowledged variations of other species, that probably no student of
these plants would at this time make use of it as a specific character.

But: this is not all; Prof. H. L. Smith now owns all of De
Brebisson’s material. Since this discussion commenced Prof. S.
has sent to me prepared from that material a slide of ‘* Nav. rhom-
boides,’ and one of “ N. crassinervia,” with the comment that he
could ‘‘see no difference between them.” After a careful study of
both slides I fully concur with Prof. Smith’s conclusion. Neither
Dr. Woodward’s photographs nor the lithograph copy of Seibert’s
photograph show any specific distinction.

* Navicula rhomboides in all its varieties is found throughout New England,
but its head-quarters seem to be in the little ponds and streams among the white
mountains of New Hampshire. There is one deposit on the bottom of Bennis Lake
(see Lewis, in ‘ Proc. Phila. Acad. Nat. Sciences,’ 1865), every slide of which will
contain hundreds of frustules of all sizes. I have measured them from +0007”
to ‘0017”, varying in closeness of striation nearly in proportion to the size. Of
course, as I consider the three names belong to but one species, I must believe
that all of them will show longitudinal striation.

( 266 )

V.—On the Measurement of the Angular Apertures of Obyject-
glasses. By Japnz Hoae, Surgeon to the Royal Westminster
Ophthalmic Hospital, F.R.MLS., &.

I am led to infer from what has recently transpired that consider-
able misapprehension prevails with regard to the measurement of
the angular aperture of object-glasses. An article contributed by
Mr. Ingpen to the Journal of the Quekett Club, and quoted in the
‘M.M.J.,’* though of some interest, only very briefly alludes to
the various methods employed during the last quarter of a century,
and does not touch upon any method that would be considered
valid in the determination of the apertures of immersion lenses.
Mr. Ingpen makes particular mention of Professor Robinson’s
method, and though he speaks of it as “a very elegant method, and
likely to be valuable, in certain disputed cases, as to the true angle
of immersion lenses,” it would appear that he thinks immersion
apertures can be measured by this method without any modifica-
tion. It is, however, quite evident that Professor Robinson had
solely in view the measuring of the apertures of dry lenses—such
as have a true air-focus ; and Mr. Ingpen offers no evidence what-
ever that he realizes what modification is necessary in Professor
Robinson’s method to render it applicable to immersion lenses.

In the Journal,t Mr. Wenham unhesitatingly affirms that Pro-
fessor Robinson’s method is by far the best. These are his words:
“JT consider that the most correct of all [methods of measuring
apertures] is that proposed by Professor Robinson, which consists
in passing the parallel rays of the sun through the back of the
objective, and then by means of a white screen in a dark room
intercepting the rays as a disk of light. The angle taken from the
diameter of this to the focal point will give the true aperture.”
Mr. Wenham also appears to think that the aperture of immersion
lenses can be accurately determined by the same method, and
without modification of any kind. On the other hand, it is held
by competent authorities who have given the subject special atten-
tion, that the only possible way of measuring immersion apertures
with accuracy is to measure the angle of the cone of rays while
they are in the condition of immersion. This view is entertained
by Dr. Woodward, Professor Keith, Professor Abbe, Messrs. Hart-
nack and Prazmowski, Messrs. Powell and Lealand, Mr. Dallmeyer,
Mr. Tolles, and Professor G. G. Stokes, whose authoritative utter-
ances on the subject are of the highest importance.

The modification required in Professor Robinson’s method to
enable anyone to measure immersion apertures is an extremely simple
one, and can be readily put into practice. In place of the white

* Page 236, May 1876. + ¢M, M. Ji’ vol. viit., p: 2d:
) »~P

Angular Apertures of Olject-glasses. By Jabez Hogg. 267

screen, a cube of glass greyed on the under surface should be so
placed that the lens may be accurately adjusted and focussed on
the upper surface in water contact, or still better, in glycerine.
The angle can then be read off the luminous disk on the greyed
surface, by applying a suitable tangent scale. I have some idea
that Mr. Wenham first proposed a cube of glass for measuring
apertures, but have been unable to verify this, although I feel sure
that the lenses so measured were dry lenses only. No true aperture
can be measured unless the lens is so adjusted as to give its best
and finest definition ; it is therefore utterly fallacious to attempt to
measure the aperture of an immersion lens unless it is adjusted for
and actually measured in immersion contact. It would be quite as
fallacious to attempt to measure the aperture of a dry lens unless
adjusted for and measured as a dry lens. If the lens is so
contrived that it can be used either wet or dry, then the aperture
will necessarily be greater when used wet than dry. I possess a
Dallmeyer’s }th, which can, by suitable adjustment, be used either
wet or dry. The angle when used wet is 70° measured in the
cube of glass, and 55° when accurately adjusted and used dry.

It may give increased weight to what I have said to add that
the modification of Professor Robinson’s method spoken of has been
submitted to Professor Stokes by Mr. J. Mayall, jun., and he
admits its validity ; and furthermore, Mr. Mayall has employed it
in my presence for measuring the aperture of various immersion
lenses ; amongst others, Tolles’ jth, belonging to Mr. Crisp, and
the measurements so made confirm Mr. Tolles’, that is, the
aperture of the lens in question was found to be nearly 100° in
the cube of glass. It is but right I should state that the aperture
of the same lens was measured by Mr. Wenham in my presence,
by his semi-cylinder and turn-table method, and with a metal stop
of = of an inch in diameter fixed in the focal plane, and the
measurement very nearly approached 100°.

I shall not enter upon the question of the utility of slits or
metal stops for measuring immersion apertures, as I believe Pro-
fessor Keith’s criticism in the Journal for December last* effec-
tually disposes of this part of the subject. I will, however, direct
attention to the fact that Mr. Ingpen appears to think the slit is
properly used when “separated to the exact diameter of any field
of view, thus excluding all but ‘image-forming rays.’” Those
microscopists who have followed Mr. Wenham’s more recent state-
ments as to the right use of the slit will at once perceive that
whilst he insists the slit should admit only the merest line of light,
Mr. Ingpen thinks it should not encroach on the field of view. It
is to be presumed that Mr. Ingpen has given the subject due con-
sideration, and I hope he will at some future time favour the

* Page 284,
VOL. XV. U

268 Angular Apertures of Object-glasses. By Jabez Hogg.

readers of the Journal with a more detailed exposition of his
reasons for considering the slit “a valuable adjunct,” while the
method in which he would employ it is so entirely at variance with
Mr. Wenham’s. I am perfectly aware that when Mr. Wenham
first brought forward his slit method he wrote, “it is preferable to
open the slit till the edges appear in the margin of the field ;”*
but in a later paper vindicating his report on the aperture of
Tolles’ ith, he appears to have abandoned this specific direction as
to the size of the slit, and he now relies on some infinitesimally
narrow slit, which he says should “cut off all lateral pencils”;
however, with Professor Robinson’s modified method no slit is
required, and most conclusive and reliable results will be obtained.

* (M.M.J., vol. xi, 1874, p. 118.

( 269 )

PROGRESS OF MICROSCOPICAL SCIENCE.

The Potato Disease.—Mr. Berkeley, writing to the ‘Gardeners’
Chronicle, says:—Since the meeting of the Linnean Society, of
which a report was given in the ‘Gardeners’ Chronicle, March 25,
1876, Mr. Smith has forwarded to me several slides containing
specimens of the organisms he found at Chiswick in 1875. Having
examined them very carefully, I think it but justice to state what I
have observed. 1. The oogonia seated on thick, often flexuous threads,
with a septum beneath the oogonium which is sometimes carried far
down the thread. 2. Many instances in which the oogonium is pro-
duced. in the middle of the thread, with a septum at either end, calling
to mind the figure of Montagne’s Artotrogus. In several instances
a process terminated the oogonia, as if the thread was to be produced
so as to leave the oogonium in the centre. 3. In one oogonium I
found an echinulate body, quite as strongly echinulate as in the best
specimens of Artotrogus. 4. The so-called antheridia produced on
delicate threads, quite distinct from those of the oogonia, and not
separated bya septum. The form of the antheridia is exactly what
Smith has figured. 5. The antheridia in contact with the oogonia, in
one instance the wall of the oogonium being perforated, as if by the
act of impregnation. I cannot, however, speak more positively on
this point. 6. Abundant Peronospora; threads and spores mixed
with the oogonia and antheridia. Of course Mr. Smith’s interpreta-
tion of what he has seen is subject to criticism, but his good faith is
so far confirmed by his specimens that criticism should be very
guarded and gentle. If I may express my own opinion, I believe
that all these objects belong to one category, and if so, I should be
ready to receive De Bary’s Phytophthora (plant pestilence) as a good
genus, differing in several respects from Peronospora.—From the
‘Gardeners’ Chronicle,’ p. 486, 1876.

The Secreting Organs of the Alimentary Canal in Insects.—In Blatta
orientalis, the common cockroach, M. Jousset has recently been
following out the course of the digestive system,* and the following
are the principal results at which he has arrived. The secretion of
the salivary glands, and this alone, is able to convert starchy matters
into glucose. The gastric ceca secrete a yellowish liquid, feebly but
distinctly acid, which dissolves coagulated albumen, casein, and fibrin.
The albuminoids are not merely dissolved, but actually converted into
peptones. In addition to this solvent property, the liquid in question
is capable of emulsifying fatty matters. It seems, in short, to
combine the properties of the gastric juice of the higher vertebrates
with those of the pancreatic fluid. The intestinal portion of the tube
does not appear to take any part in the digestive function; the pep-
tones, oily matters, and sugar, undergoing absorption before the food

* See ‘Comptes Rendus,’ Jan. 3; and ‘ Acad.,’ Feb, 12.
w2Z

270 PROGRESS OF MICROSCOPICAL SCIENCE.

leaves the stomach. The secretion of the Malpighian tubes exerts no
action on the albuminoid, starchy, or fatty matters. It contains uric
acid and urates, and is, in all likelihood, wholly excrementitious.

A New Classification of Cryptogams has been proposed by Professor
J. Sachs, and is partly given in the botanical notes of the ‘ American
Naturalist ’ (March ).—Professor Sachs proposes a new classification of
the lowest section of eryptogams, which he distinguishes as Thallo-
phytes, including the classes, hitherto considered distinct, of Algz,
Fungi, Lichens, and Characew. He divides the section into four
classes, each consisting of two parallel series, the one containing
chlorophyll and commonly known as Alge (including Characez) ;
the other destitute of chlorophyll and commonly known as Fungi
(including Lichens). The classes are as follows:—Class 1. Prorto-
puyTa. This class comprises the simplest known forms of vegetable
life, unicellular, or the cells connected into filaments, rarely into
more complicated tissues; no mode of sexual reproduction is known.
To the chlorophyll-containing series belong the Chroococcacee, Nosto-
cacece, Oscillatoriee, Rivulariacee, Scytonemee, and the Palmellacee (in
part); to that destitute of chlorophyll the Schizomycetes (bacteria) and
Saccharomyces (yeast). Class 2. Zycosporem. Asexual propagation
various ; sexual propagation by means of zygospores, the result of a
process of conjugation. This is divided into two sections. In the
first the conjugating cells are locomotive, as in the Volvocinee and
Hydrodictyee (containing chlorophyll), and the Myxomycetes (destitute
of chlorophyll) ; the second section includes the forms in which the
conjugating cells are stationary, namely, in the first series the
Conjugate (comprising the Mesocarpee, Zygnemee, Desmidiee, and
Diatomacee); in the second series the Zygomycetes (comprising the
‘Mucorini and Piptocephalide). Class 3. Oosporrm, Reproduction by
oogonia, containing an oosphore or embryonic cell, becoming an
oospore or resting spore by the act of impregnation. Im the series
containing chlorophyll are Spheroplee, Vaucheyia, the Gidogoniee, and
Fucacee ; in the series destitute of chlorophyll the Saprolegniew and
Peronosporee. Class 4. Carposporrem. A distinct organ, or “ sporo-
carp,’ results from the process of the fertilization of the female organ,
or carpogonium. In the first series are the Coleochetewe, Floridew, and
Characee ; in the second, the Ascomycetes (including Lichens), Aici-
diomycetes, and Basidiomycetes. 'This classification of the lower eryp-
togams appears to be founded on sounder principles and a more
thorough knowledge of their structure, and especially their mode of
reproduction, than any hitherto proposed.

Characters of the Slime of Phosphorescent Fish.—It is stated by
K. F. Pfliiger,* after giving some observations on the relative phos-
phorescence of fresh-water and salt-water fish, that the microscopic
structure of the slime covering the bodies of phosphorescent fish
was then investigated. It was found to consist of lower organisms, the
so-called schizomycetes, which are the proper luminous materials.

* Pfliiger’s ‘ Archiv,’ xi.

PROGRESS OF MICROSCOPICAL SCIENCE. 271

This was shown by a filtration experiment, where the organisms were
retained upon the filter (fine thick non-sized printing paper; Swedish
filtering paper does not do) which remained luminous, while the
perfectly clear filtrate was absolutely non-luminous, this clearly
showing that the small living cells of the schizomycetes are the cause
of the luminosity; and further, the author’s experiments furnish
strong proofs that the schizomycetes do not arise “ spontaneously,” but
from spores.

On the Development of Spindle-cells in Nested Sarcomas. —
Dr. Gowers read an able and interesting paper on this subject before
the Pathological Society, which has been thus reported by the
‘Lancet’ of April 22:—The tumours thus designated consisted of
spindle-cells with a few round cells, and had, further, this pecu-
larity, viz. that the spindle-cells were in part arranged concentrically
in nests, resembling very closely the nests of epithelioma. The
microscopical characters of the cellular elements were fully detailed.
The nuclei of the cells were larger in proportion to the size of the
cell in the softer and more rapidly growing parts of the tumour,
while in the denser portions the cells were finer and more like fibres.
In some parts, round cells were observed in process of development
into the spindle-shaped varieties. The “ cell-nests” varied from ,35
of an inch to 5}, of an inch in diameter, and were distinctly seen to
be composed of concentric layers of fusiform cells, the outermost
layers being in many specimens partly detached. These observations
were founded upon three examples of the tumour which sprang from
the inner surface of the cranial dura mater: they were globular and
nodulated, and had displaced the brain-substance in their vicinity.
They varied in consistency, but the older portions of the growths
were firmer than the more recent parts, and in one specimen the
whole tumour was soft throughout. In colour the growths were of
a reddish grey, the softer parts resembling in tint and consistency
grey cerebral substance. In these tumours the origin of their con-
stituent spindle-cells could be readily traced; the process being
found to consist in an endogenous development from round cells,
the process described as vacuolation by Dr. Creighton. The fol-
lowing is a brief outline of the changes as observed in different
stages of progress in different parts of the growth. The nucleus
of the small delicate-walled round or oval cell, which is at first in
or near the middle of the cell, becomes excentric in situation, whilst
a clear space occurs in that part of the cell which is away from
the nucleus; and as the cell increases in size its granular proto-
plasmic contents become more and more confined to the periphery,
till at length the “ crescentic” or “ signet-ring” form of cell is
produced: The nucleus now lies imbedded in the protoplasm where
this is thickest. Gradually the inner margin of the crescent-shaped
body becomes more defined, until at length there is produced a
spindle-cell, which gradually separates from the central mass of the
original cell-body. Many were seen in process of separation, and in
those recently detached their crescentic shape denoted the manner in
which they had arisen. When the original nucleus remains single

272 PROGRESS OF MICROSCOPICAL SCIENCE.

the spherical cell only gives rise to a single fusiform cell; and if
the nucleus divides after it has acquired its lateral position, the
resulting spindle-cell contains two nuclei. But occasionally the
division of the nucleus takes place before or soon after the process
of vacuolation commences, and in this case one nucleus remains
behind within the hyaline area, and is often surrounded by some
granular protoplasm. It may here be developed into another cell,
thus lying within the first spindle-cell. The repetition of this
process by repeated multiplication of the nuclei produced the con-
centric nests. This process of vacuolation can only be distinctly
seen in the rapidly growing portions of the tumour, and it was only
distinct in fresh specimens. The exact nature of the process and of
the hyaline contents of the vacuoli is uncertain. It would appear
that these contents are composed of some new, delicate material, at
first protoplasmic. The process may be regarded as a simple move-
ment of the nucleus and granular protoplasm to the periphery of the
cell, but the sharp outline of the vacuoli and the tenuity of the peri-
phery suggest that there is an active distending force concerned in
the process. Vacuolation in most cases terminates the active life of
the original cell; and division of the nucleus only leads to multipli-
cation of the cell if it precede or accompany, not if it succeed, the
vacuolation process. The paper concluded with a reference to various
descriptions and drawings of the process by different writers, who
have, however, for the most part misinterpreted its nature. The
examples show how various is the part played by the process in tissue
changes. The paper was illustrated by a series of well-executed
drawings.

Mr. Knowsley Thornton had recently examined carefully some spe-
cimens of peritoneal cancer, and had found numerous vacuolated cells
surrounded by rings of protoplasm. He had never seen anything like
an intrusion of other cells into the vacuoli; and concurred with the
view maintained by Dr. Gowers as to the endogenous formation of the
new cells. In some specimens a round cell presented central vacuola-
tion, an excentric nucleus surrounded by granular protoplasm, within
which a development of small cells appeared to be taking place.
Staining reagents brought clearly into view the darker granular mass
bounding the cell, and this mass seemed to be undergoing a process of
cleavage. He had not been able to trace, as Dr. Thin had, the cells
to their original starting place; but in the peritoneum he had noticed
projections of oval or round masses of granular material from the
stomata, surrounded by germinating endothelium. He could not
satisfy himself as to the origin of this material.

Dr. Thin agreed with Dr. Gowers that the process of vacuolation
was not a new discovery. He had, however, never heard it so expli-
citly stated as on the present occasion. Had Dr. Gowers disintegrated
any of the large “ nested cells,” and did he believe that division of the
nucleus was essential to the formation of the second cell? With
regard to Mr. Thornton’s remarks, he was surprised that the ideas of
stomata and lymph-canalicular systems should be so generally adopted.
Many able histologists, including Ranvier, had denied the existence of

PROGRESS OF MICROSCOPICAL SCIENCE. 273

these stomata. Nor did he (the speaker) believe in the germination
of epithelium. With regard to endogenous cell-formation, all its
appearances were explained by the entrance into the cells of leuco-
cytes, a process which he was convinced did occur. He had devoted
much time and labour to enable him to recognize lymph-corpuscles,
and he thought he could recognize in the drawings accompanying
Dr. Gowers’s paper evidence in support of his view.

Mr. Hulke said that he would receive with very much hesitation
the statement that leucocytes have such a remarkable tendency for
wandering into the tissues and into other cells. In a leucorrheal dis-
charge one found numerous large definite squamous cells, containing
not one, but two, three, or four definite rounded bodies, which cer-
tainly were not leucocytes. He instanced also the case of suppuration
of the vitreous humour, enclosed in its definite hyaloid membrane,
and separated from the choroidal capillaries by the membrana limitans
and the whole thickness of the retina and the pigmentary epithelium
and elastic lamina of the choroid, and thought that the travelling
powers required by the leucocytes to penetrate all these structures
were more than could be granted. On the other hand, the vitreous
possesees traces of foetal structure, vestiges of embryonic cell-tissue,
which can be seen distinctly to be enlarged and replaced by bodies
indistinguishable from pus-cells. He was then very sceptical about
the enormous powers which were attributed to the white blood-cells.

Dr. Gowers, in reply, remarked that Mr. Knowsley Thornton’s
observations on the multiplication of nuclei in the peripheral zone of
vacuolated cells were interesting. He had not observed such multi-
plication after vacuolation, and asked whether they might not have
been formed before vacuolation, and pushed to the periphery by the
process. In reply to Dr. Thin, the character of the outer cells of the
nests could be seen readily, since one or two were often half detached ;
they were simple spindle-cells curved according to the shape of the
globe. He could not accept Dr. Thin’s view that the second nucleus
within a vacuolated cell was a leucocyte which had wandered in. The
nucleus resembled closely the original nucleus of the cell. Ifa
nucleus were seen in a certain position, he thought that the first
inference suggested was that it had been formed there, not that it had
wandered in. This inference was strongly supported by observation
of the nests of cells, since there was a simultaneous increase in the
number of nuclei in the centre and of spindle-cells in the outer part
of the nest. But the more numerous the circumferential cells, the
greater the obstruction to the entrance of cells from without; and it
was therefore probable that simultaneous increase in the nuclei within
was due to their formation at the spot, and not to their migration from
without.

Measurement of Nobert’s Bands.—A very valuable paper on this
subject was some time since laid before the Royal Society, and we had
hoped to have had an opportunity of reproducing it in full in these
pages. As the opportunity has not offered, we think it better to
give a portion of the essay, that relating to Nobert’s bands, and to
give the general conclusions at which the author arrives. The paper ~

274 PROGRESS OF MICROSCOPICAL SCIENCE.

in question will be found in the ‘ Proceedings of the Royal Society,’
No. 163, and it is by Mr. J. A. Brown, F.R.S.
The following table contains the results of the observations of

Nobert’s test-lines.

Measures oF Nopert’s Test-Lines.

Width of Number to the Inch,
Band of Ratio.

! Lines. Line Space Band. Lines. Spaces. Both.

Teh % 18°52 / 1 SRPRT 553 35,000 | 17,040 | 11,460 1:00
II.| 10 | 35°10 23°00 560 28,500 | 43,450 | 17,210 1°68
It.| 13 | 27°85 | 14°85 555 35,910 | 67,340 | 23,420 | 2:11
Vo to ie ts oy, 505 52,270 | 64,230 | 28,820 | 3:10
V.| 17 =| 14°10 | 15°20 480 71,430 | 65,790 | 34,250 | 3°87
WE. | 20%) 55 6 1 13790 495 86,580 | 71,940 | 39,290] 4:23

VIL| 23 | 12°64 9°14 | 505 79,110 | 109,410 | 45,910 | 4:65
VuL| 25 | 8-71 | 10-71 | 475 1114810 | 93,370 | 51,390] 5-49
EX, ||" 28 T-47 9-95 478 133,870 | 100,700 | 57,470 5°92

X.}| 30 8°11 7°44 460 123,300 | 134,410 | 64,310} 7°25

MI | 34 |} 8°10 6°90 500 | 123,300 | 144,930 | 66,670 | 7-25
XIL| 37 | 6-81 | 7-28 | 503 |146,840 | 137,360 | 70,970 | 8-08
XIII 40 6°62 6°00 500 151,060 | 166,670 | 79,240 8°89
XIV 43 6:00 6-00 510 166,670 | 166,670 | 83,330 9°81
Ve. IS A |) Oso 9°56 495 179,860 | 179,860 | 89,930 | 10°50
VEE G40) 9. ; 522 u3 77,280
—_ 503
XVIL| (40) |. ¥ (aiat 77,880
XVHI.| (40) |. . eri} bi -aeroe (oD
MEX, |/¢40y|/ 4 u 540 . .. | "75,760?

| | i

Notes.—These measures are frequently mere approximations; and in several
hands the graying-point has made a wonderful approach to an equality of width
of lines and spaces; indeed, these lines are marvels of mechanical skill. If, in
the case of each band, the first and last lines had been drawn longer than the
rest, it would have been possible to measure the width of a line with considerable
accuracy, since, as has been shown, the visibility of a single line is nearly twenty
times that for the series.

The oa of the lines and spaces are those taken from the photographs, the
unit being —,, inch. The photographs are magnified to 1000 times. In bands
XVII. and XVIII. second measures are given from photographs magnifying to
1600 times (but reduced to the same unit). The number of lines in ( ) are the
numbers counted for which the total width was measured. The number for the
XIXth is deduced from the measure of a few where the lines were most distinct.
‘The numbers of lines and spaces to an inch are the numbers which could be put
in an inch laid side by side (without interval). Under “Both” is given the
number of lines to the inch (with interspaces), as in the bands. The “ Ratio”
is that of the number for the widest space (17,000 to the inch) to the number for
the widest line or space in the following bands.

It will be seen that the least width of the — which can be
counted and measured on the photographs is about of an inch
(XIIIth band). We have seen (5th observation) fa dark parallel
lines on glass can be seen with transmitted light when their width
subtends an angle of 20" to 26”; so that lines stopping the light
moderately (7th observation) of +g gy55, of an inch wide should be

PROGRESS OF MIGROSCOPICAL SCIENCE. 275

seen with a power of 125, and counted with a power of 160 (the
distance for the unaided eye being considered 8 inches). We have,
however, obviously in the high bands to include the case of observa-
tion 7, the lines on the photographs being excessively faint. When
we add to this fact (a most important one when such lines are sup-
posed to give some measure of the power of the microscope) that it
appears that separate lines canndt be drawn of a less width than
about +s oop of an inch under the diminished pressure of Mr.
Nobert’s machine without the graving-point sliding into previous
grooves, we have a sufficient explanation why the power of the micro-
scope cannot be measured by these lines,

The following are the conclusions of this note:

1st. That lines can be seen by the naked eye with transmitted
light the width of which subtends an angle of about 1”.

2nd. That the visibility of a line, or the distance at which it can
be seen, depends on the logarithm of its length, the product of the
angle subtended by the width and the cube root of that subtended by
the length being nearly constant.

8rd. Short parallel lines could be seen by transmitted light when
the angle formed by the width of the spaces and intervals was 20".

4th. The visibility of lines of the same width increases as the
distance between them decreases.

5th. The visibility of parallel lines depends on the darkness of the
shade or tint of the lines up to a certain feeble tint, after which no
blacking of the lines increases the visibility ; the distance to which
the lines can be seen depends on c’, where ¢ is a constant and ¢ is the
number of the tint or shade (the number of coats of a weak tint).

6th. The visibility of dark parallel lines lighted with a candle
depends on the logarithm of the distance of the candle from the lines ;
and they can be seen as well with a candle placed quite near as-with
the strongest daylight. This results from Tobias Mayer’s observations.

7th. The visibility of parallel lines depends on the logarithm
of their length, as in the case of single lines, the variation being
much greater for short parallel lines than for long ones. Also for
short parallel lines the product a </ 8 is nearly constant, as for single
lines.

8th. Parallel lines are least visible when there are only two, and
increase in visibility with their number.

9th. Nobert’s test-lines fail as a test for the microscope, especially
in the highest bands, from the incapacity of the machine to make
separate lines at less intervals and of less width than ygop95 of an
inch ; they also fail, in all probability, on account of the faintness of
the tint or shade of the lines made on the retina.

A peculiar Process of Development in certain Fungi has been
recently recorded before the French Academy, and has been well ab-
stracted by the ‘ Academy, which says that M. Ph. van Tieghem has
_ made fresh observations on the development of agarics of the genus
Coprinus, and on the supposed sexuality of Basidiomycetes, which differ
from the conclusions lately arrived at. He finds that certain rods
(batonnets) which appeared to be male organs, and to act as fecun-

276 PROGRESS OF MICROSCOPICAL SCIENCE.

dators, are capable of independent germination. “These organs,”
he says, “are therefore not male fecundating corpuscles (spermatia
or pollinides), but a particular kind of spore, usually alterable and
ephemeral.” He also states that he has seen the fruits of C. plicatilis,
radiatus, and filiformis develop and ripen in a cell, or a mycelium,
under conditions in which no rods were produced or introduced.
The incapacity to germinate, alleged on the part of the rods, was,
M. van Tieghem says, only a negative argument, which falls before
the fact of their germination, which has been ascertained. If some
of the rods are placed in a drop of manure water they are seen in a
few hours to become oval, and even spherical, after which they push
forth vigorous mycelium tubes, which branch and anastomose. Two
days later, the mycelium produces more groups of baguettes, which
disjoint themselves into the rods. This is their normal generation.
If, however, they are sown in great numbers, so that they are close
together in the nutritive fluid, the conidia do not enlarge sensibly,
but emit very narrow tubes perpendicular to their axes, which ana-
stomose like the letter H. If the rods are transferred to a drop of
fluid, in which a mycelium of the same species is already developed,
they behave in an analogous manner, and anastomose with the myce-
lium. If at the point of union the mycelium branch is somewhat
exhausted, they pour their protoplasm into it, and renew its activity.
After supplying further details, M. van Tieghem says: “The various
copulations of the rods we now know are vegetative phenomena, begin-
nings of germinations under conditions in which normal germination
cannot be accomplished, and with manifestations of the general pro-
perty of anastomosing and grafting, which all the cells of these plants
possess in a high degree. ... The theory of the sexuality of the
basidiomyeetes, apparently based upon the most demonstrative of pro-
cesses, cannot resist a more profound study. Will it be so with the
basiomycetes? This will be treated in another paper.”

Emigration of Blood-corpuscles——Herr J. Arnold has been investi-
gating this subject, especially with regard to the conditions of the
walls of the blood-vessels during the passage of the corpuscles. He
states* that he injected a weak solution of silver into the blood-vessels
of frogs, in which single parts of the body had been inflamed twenty-
four hours previously. The appearances of the so-called endothelial
figures varied considerably from the normal. The “cement lines” ap-
peared as broad, strong, zigzag lines, or were only indicated by rows of
granules. There are large dark points in them, the stigmata ; and in
the cement substance as well as in the stigmata are to be found white
corpuscles in the act of passing out of the vessels, and this in various.
stages of their passage. Not unfrequently several colourless corpuscles
are to be seen attached to one part of the cement substance, or to one of
the stigmata ; thus, two corpuscles may be lying within the vessel, and
fixed by short processes in a stigma, whilst a third one for the most
part has penetrated and only remains in connection with the vessel
by means of a short process. Sometimes the accumulation of the
white corpuscles on the outer side of the vessel, in the neighbourhood

* Virchow’s ‘ Archiv,’ Bd. Ixii., p, 47; and ‘Med. Record,’ Feb. 15.

NOTES AND MEMORANDA. 277

of the stigmata, is so considerable, that the sheath of the vessel, at the
corresponding spot, stands out like a little hump from the epithelial
layer. From this the author concludes that the white blood-corpuscles
in inflammation pass through the wall at the cement substance, i. e.
the stigmata; whilst, on the contrary, he never saw that other parts
of the wall of the vessel, e.g. the epithelium, was permeable to the
white blood-corpuscles. From experiments made with gelatine and
fine vermilion injections, it seems that, in addition to the pronounced
wandering out of colourless blood-corpuscles connected with disturb-
ances in the circulation, other corpuscles also pass through the wall
of the vessel ; and apparently this also happens at the portion of the
stigmata and cement substance. When blue-coloured gelatine instead
of the vermilion was employed, the inflamed vessels at numerous
spots here seemed to be covered with small roundish blue protube-
rances, or with more elongated blue processes. From this it results
that the wall of the vessel permits not only substances in solution
to pass through it at the position of the stigmata and cement substance,
but also a colloid body (gelatine) and other elements (vermilion).
The masses which have passed through the vascular walls, penetrate in
the direction of the “juice canals” (“ Sa/tcanalsystem”) in the tissue, and
under certain circumstances these can be completely filled laterally
with the injection mass. Still the configuration of this system of
spaces when injected is variable, according to the disturbances of the
circulation which have occurred in the tissues. Whilst the juice-
canals during venous stasis possess a broad and ampullated form, they
appear smaller, and more zigzag in those disturbances of the circu-
lation which are specially characterized by the exit of white blood-
corpuscles.

NOTES AND MEMORANDA.

A New Form of the Phylloxera.—M. Balbiani, the distinguished
entomologist, has addressed to M. Dumas a letter on the egg of the
phylloxera, from which the following passages are gleaned as being
of importance :—“I have to inform you that on examining, this
morning, April 9, through the magnifying glass, a certain quantity
of winter eggs I had collected a few days ago (there were some
twenty of them on the same bit of vine shoot, 19 centimeters long),
my attention was suddenly attracted to a yellow point there was
among these eggs. It turned out to be a young phylloxera just
hatched, for the little parasite still carried the egg-shell about with
him. For more than two hours it remained perfectly motionless,
but all its appendages, feet and antenne, were entirely spread out and
well visible. At lergth it began to move, and soon grew rather
lively on the lamella of bark on which it stood. By microscopic
inspection I acquired the conviction that the offspring of yesterday’s
egg, which, according to all analogy, represents the fundamental
progenitor of the subterranean colonies, really constitutes a fourth

278 CORRESPONDENCE.

specific form of the vine phylloxera; for it has characteristies that
distinguish it from all other shapes hitherto known. . . . Its size is
;'2, of a millimeter in length by 16 in breadth. It has long and
slender antenne, a fusiform terminal article attenuated at its base
and a well-developed rostrum, the point of which advances down to
the middle of the abdomen. . . . The individual I have been de-
scribing is the only one of its generation I have yet obtained; I
cannot therefore give any information as to its habits; but among the
eggs that were on the same vine shoot there are several containing a
well-developed embryo, which is recognizable by its two red ocular
points, visible through the teguments of the egg. I hope, therefore,
to be able to make some further observations.”

Microscopy at the American Association. — This, which has
hitherto been feebly developed, bids fair to become a prominent part
of the Association in future years. This Section, which was formed at
the last meeting, is now undergoing favourable development. The
club which has been started for the purpose, now invites all persons
interested in the microscope, and desirous of joining such an organiza-
tion as is now proposed, to be present and co-operate, whether at
present members of the Association or not, and they are requested
to bring to the meeting original papers of scientific interest upon
subjects connected with the microscope and its work, and also to
bring instruments, accessories, and objects, especially those illus-
trating new or unfamiliar inventions, contrivances, and discoveries.
It is hoped that the participation of microscopists in this movement
will be prompt and cordial.

CORRESPONDENCE.

To the Editor of the ‘ Monthly Microscopical Journal.’
Hogart CotLece, GenEvA, N.Y., April 10, 1876.

Sir,—Mr. Hickie in his reply to Dr. Woodward, in the March
number of the ‘Monthly Microscopical Journal,’ makes two distinct
issues: First, Frustulia Sawonica has true longitudinal lines; and
second, Frustulia Saxonica is not Navicula crassinervis. I do not
intend to discuss the first; Dr. Woodward and Mr. Hickie must settle
that for themselves; but the second statement is, in my opinion,
erroneous; and I am sure Mr. Hickie, when he has made more com-
plete study of the Diatomaces, especially as to what is to be con-
sidered of value in establishing species and genera, will agree with
me. Let him read Mr. Kitton’s article on “the publication of new
Genera and Species from insufficient material.” *

Mr. Hickie sums up the evidence in favour of his assertion

* « Journal Quekett Microscopical Club,’ Feb. 1867, and published in ‘Q. M. J.,’
vol. vii., N.S.

CORRESPONDENCE. 279

that Frustulia Saxonica and Navicula crassinervis are not the same
diatom, as follows.* “Dr. Rabenhorst discovered a certain diatom in
Saxon Switzerland and named it Frustulia Saxonica. De Brebisson
also, as I understand, discovered a certain diatom and named it
Navicula crassinervis, and did so under the impression that what he
so named was something totally different from what Dr. Rabenhorst
had called Frustulia Saxonica. Dr. Rabenhorst, again, in the letter I
read to you, says expressly, that he who identifies these two diatoms,
must be ignorant of one or other of them

“ Now, if there be any two greater Continental authorities than
Dr. Rabenhorst and the late De Brebisson, I should like to know
who they are.”

So far good. I accept the position. Let us see what these two
great Continental authorities really do say—not by letter, now when
they have forgotten what they have really said before (which indeed
is not remarkable for Dr. Rabenhorst, who is a most industrious com-
piler), but what they published, when the subject was under fresh inves-
tigation. First, Dr. Rabenhorst. In his latest publication on the
Diatomacez, as a whole, ‘Flora Europea Algarum, Sectio I, Algas
Diatomaceas Complectans,’ p. 227, he says, “ Frustulia Saxonica, var.
c, forma aquatica (Navicula crassinervia Bréb. 1852! in Sm. Diat.
p- 47, tat. xxxi. f. 271).” Observe, this has the botanical mark of iden-
tification! and, curiously enough, he says, “ striis obsoletis, longitudina-
libus distinctioribus.’ How about the ignorance of the Doctor himself ?
But now, second; the other “ great Continental authority,” and justly
so called. Ina paper published in ‘ Annales de la Société Phytolo-
gique et Micrographique de Belgique, 1868, upon Vanheurckia, a new
genus of the Diatomacex, Brébisson says, “ V. crassinervia Bréb.—
Nav. crassinervia Bréb. MSS. W. Smith, Brit. Diat. i. p. 47, pl. xxxi.
f, 271—Frustulia torfacea Braun, et Nav. Saxonica (Frustulia) Raben.
Diat. 50, t. 7.” How about De Brebisson’s ignorance ?

Here, then, each of Mr. Hickie’s authorities states that N. crassi-
nervis and Frustulia Saxonica are the same; moreover, in Rabenhorst’s
Algen, as stated by Grunow, Navicula crassinervis Bréb. occurs in his
No. 48, as Frustulia Saxonica, and Grunow himself, quite as good an
authority, to say the very least, as Dr. Rabenhorst, states explicitly, in
“‘ Ueber neve oder ungentigend gekannte Algen,” ‘ Verhandl. der K.k.
Zool. Bot. Ges.’ x. B. 1860, p. 573, “ Frustulia Saxonica Rabenhorst,
ist Navicula crassinervis Bréb.,” &e. Mr. Ralfs, who does not seem
to have examined any authentic specimens of N. crassinervis, but
gives Rabenhorst’s description, remarks, in Pritchd. Infs. p. 924,
“ F, Saxonica (Rab.) slenderer than F’. torfacea,” but the latter, he says,
“from an authentic specimen appears to be identical with Navicula
rhomboides.” I have already noted that De Brébisson considers F,
torfacea and F’. Saxonica the same. Again, W. Smith, in the British
Diatomaceex, vol. ii. p. 69, suggests that Nav. crassinervia (this was
the original name, it should be “crassinervis”) is the free state of
Colletonema vulgare, and in this he was undoubtedly right; and Donkin,

* See ‘M. M. J.,’ March 1876, p. 127.

280 CORRESPONDENCE.

in Brit. Diat. pt. ii. pl. v. f. 3, has figured a small specimen of this as
Nav. dirhynchus E. Again, N. G. W. Lagerstedt, in his ‘ Fresh-water
Diatomacee from Spitzbergen and Behring Island,’ gives the following
list of synonyms, p. 832: “N. Saxonica Rabenh.—Frustulia Saxonica
Rabenh. Bac. Sachs, No. 42 (1851) (see Rabenh. Fl. Eur. Alg.
Diat.). Grun. in Rabenh. Beitr. H. 1i. p. 10, t.i. f.13. N. crassi-
nervia Bréb. in Wm. Sm. Syn. Brit. Diat. v. i. p. 47, p. xxxi. f. 271.
Grun. in Wien Verh. 1860, p. 548, t. 3, f. 12.”

But once more. Mr. Hickie has expressed a very high opinion of
Schumann’s ‘ Diatomeen der hohen Tatra.’ In this remarkable ! work,
p. 79, I find “ Frustulia Saxonica Rabenh..... Sie tritt in folgenden
Formen auf. 1. Nav. crassinervia Bréb. Syn. (Brit. Diat.) s. 47, xxxi.
271.” Dr. Pfitzer, in his ‘Untersuchen iiber Bau und Entwick-
lung der Bacillariaceen, Bonn, 1871, p. 61, enumerates the particu-
lars in which Colletonema vulgare and Frustulia Saxonica agree, so that
if W. Smith, Brit. Diat. vol. ii. p. 69, is right, we have here another
evidence of identity between Navicula crassinervis and Frustulia
Saxonica. Suppose now we tabulate results, naming only authorities.

In favour of the identity. Against it.
Rabenhorst, in 1864. | Rabenhorst, 1875.
De Brébisson.
A. Grunow.
Ralfs, by inference. |
W. Smith, ditto.
Lagerstedt.
Schumann.

Pfitzer, by inference.

It is true that Mr. Hickie quotes Mr. Morehouse; but with all
credit to the skill of this gentleman in resolving test-objects, I do not
think he claims to be an ‘authority,’ and I presume knows the
diatoms in question only as named by Moller, and other dealers.

Finally, the genus Frustulia should be abolished ; and I am quite
sure that Mr. Kitton, who is, I suppose, at the present time, one of the
best, if not the best of English authorities, will agree with me. It
was constituted to receive species of Diatomacez imbedded in amorphous
gelatinous substance. I have repeatedly observed Colletonema vulgare,
which in running water is found in tubes, when transferred to quiet
water, and exposed to good light, to lose all traces of tubular structure,
developing only an amorphous gelatinous mass ; and the little Navicula
atomus = Frustulia pelliculosa is very remarkable in this respect. Mr.
Hickie is right in mniting Frustulia (Nav.) Saxonica with Navicula
rhomboides. The latter often occurs in tubes, and De Brébisson’s
Frustulia (Vanheurckia) viridula is identical with Navicula rhomboides,
and also with his Nav. crassinervis. I have specimens of all these
direct from him, and the difference is too slight to warrant, with our
present views as to what is sufficient for such a purpose, the establish-
ment of new species; they merge into each other by almost imper-
ceptible gradation. Everyone who has studied the Diatomacezx, except
as curiosities, or as test-objects, nay, even in this latter case, is aware

CORRESPONDENCE. 281

of the great variation in outline and striation in the same species,
and this, not only when contrasting sporangial forms, and their im-
mediate successors with the parent frustules, but as dependent upon
surroundings. Disregarding, then, thei fleeting characteristics, and
looking at the subject from a somewhat higher plane, and with broader
views, simplifying rather than confusing the study of these interesting
organisms, I cannot but consider them all as varieties of Ehrenberg’s
Navicula rhomboides.

Most of the group to which the so-called Frustulias belong still
retain an investing sheath or cuticle, enveloping the frustule when it
is separated from the gelatinous mass, or the tubes, and which becomes
dark brown upon burning, and often wrinkled. If the burning is in-
sufficient, the colour still remains: as most of the dry preparations are
now made by incineration, this may account for the colour noticed by
Mr. Hickie. In the closely allied Amphipleurece, the wrinkled sheath
gives an appearance of resolvability to some frustules even with very
low powers; and I have often noticed this with Colletonema vulgare.

H. L. Smita.

| Professor H. L. Smith having requested me to revise the proof
of the above letter, I take the opportunity of stating that I fully
agree with him that the genus Frustulia should be abolished; and I
am also of opinion that Navicula crassinervis is only a form of N. rhom-

boides. I may also state that my friend Mr. Hickie is of the same
opinion.—F,, Kirton. |

Mr. Tonues’ 37TH acain! *

To the Editor of the ‘ Monthly Microscopical Journal.’

Boston, May 2, 1876.

Sir,—We have the authority of Mr. Wenham, found on p. 225 of
‘M.M.J. for May last, that a certain 1th objective did work through
a plate of glass -018” thick, and this is given as the thickest it would
penetrate and come to a focus on the under surface thereof. This

distance in glass he has repeatedly said is practically the same as in
balsam.

* Mr. Tolles has sent us besides the above, another communication on the
same subject, which, however, we decline inserting. We must positively refuse
publication to any other letters relating to Mr. Tolles’ particular apertures, which
‘we are sure our readers are heartily weary of.

By comparing the figures on the above diagrams with the dimensions given
by Mr. Wenham on page 153 of this Journal for March, and at page 184 for
April, it will be seen that Mr. Tolles in both of them, in order to make out his
case, has taken different dimensions of working diameter and focal distance from
those of Mr, Wenham. This is mere contradiction, and no argument.

Mr. Wenham in his article in this Journal for April last, page 185, now stands
responsible for the statement that “all measurements for ascertaining large aper-
tures have hitherto been erroneous, and far in excess of the true pencil.” As this
is of importance, we shall be glad to afford space in our pages for a proper dis-
cussion as a pure question of science. If it is taken up as a personal one, letters
having this tendency will not appear in our pages.

282 PROCEEDINGS OF SOCIETIES.

The diagram, Fig. 1, is his own (except the dotted lines), showing
118° to be the utmost possible for the lens, on the assumption that
the whole diameter, -043", is used, and that all the rays cross at the
focal distance of -013" in air. The dotted lines added by me cross
at *018" distance from the face of the lens, and show an angle of

Hires.
: Fig. 2.

100°. Were the whole exposed front surface used, this would be the
balsam, i.e. glass angle of the objective, provided the cover thickness
is given correctly.

Fig. 2 shows the same diameter, -043”, and the same focus
through covering glass, = -018", and a used diameter of -036"; thus
twice the focal distance (= +036") represents the used diameter
giving a right-angled triangle with 90° at the focus.

His own later “utilized diameter”? makes the balsam angle some-
what less, closely to 88°, but leaves the argument conclusive against
his assertions of small angle in the objective.

By my own measurement the working distance of the objective
through glass cover is less than *018”’, and accordingly the balsam
angle I claimed and claim is more than his data afford, but either
exceed the equivalent (82°) of 180° in air.

Yours respectfully,
R. B. Toutes.

PROCEEDINGS OF SOCIETIES.

Royat MicroscopicAL Society.

Kine’s Cotiece, Vay 3, 1876.

H. C. Sorby, Esq., F.R.S., President, in the chair.

The minutes of the preceding meeting were read and confirmed.

A list of donations to the Society was read by the Secretary, and
the thanks of the meeting were voted to the donors.

Mr. Charles Brooke said he had a very pleasing duty to perform
before proceeding to the business of the evening, and that was to
propose that the best thanks of the Fellows of the Society be given

to their President, Mr. Sorby, for the soirée which he gave to them
‘

PROCEEDINGS OF SOCIETIES. 283

and to their friends on the 21st of April. He felt sure they must all
have felt highly gratified at the very admirable manner in which the
arrangements were conducted, and must have been extremely pleased
with the interesting entertainment provided for them on that occasion.

The motion having been seconded by Mr. Fitzgerald, was put to
the meeting by Mr. Brooke, and carried unanimously.

The President expressed himself as much obliged to the Fellows
of the Society for the kind manner in which this vote of thanks had
been proposed and carried. In making arrangements for a conversa-
zione of that kind, it happened sometimes that many things might
turn up to interfere with success, and which it was not possible to
foresee or to provide against, but in this case he was glad to find that
everything went off as well as could be expected. For his own part,
he could only now wish to thank those Fellows of the Society who
assisted on the occasion by the exhibition of so many beautiful and
very interesting objects.

Mr. Blake read a paper “ On what appeared to be Foraminifera in
the Coralline Oolite.” Specimens in illustration were exhibited under
several microscopes in the room. (The paper is printed at p. 262.

The President, in proposing a vote of thanks to Mr. Blake for his
paper, said that personally he felt exceedingly pleased that Mr. Blake
had succeeded in finding these things in the condition in which he
had described them, and there would now appear to be good evidence
for deciding that they were Foraminifera, a matter which it had been
extremely difficult to decide before. He called attention to a diagram
suspended in the room, and which represented the results of some of
his own observations upon the same subject made many years ago;
and said that in a majority of cases he was unable to find any evidence
that these little bodies were, or had been, shells, but in a few instances
there was some indication round the margin as if it had resulted from
dirt getting into the shell, and although he had found this several
times, he doubted whether he could rely upon that sort of evidence
alone, although his own opinion was that they had been shells. The
position in which Mr. Blake had found them was also a matter of
interest, as rendering it probable that they were also to be found in
calcareous grit, and coralline oolite over a very wide area.

The thanks of the Society were voted to Mr. Blake for his paper.

Mr. Jas. Glaisher said that about a year since, he had the pleasure
of introducing to the Society Dr. Gayer; that gentleman had then
some experience in micro-photography, and he had urged him to
persevere in it, and to communicate the results to the Society. This
he had done, and judging by the specimens which were placed upon
the table that evening, he had not done so without success.

A number of beautiful photo-micrographs were then handed round
for the inspection of the Fellows, and a paper by Dr. Gayer describing
the apparatus employed and the process of manipulation was read to
the meeting by Mr. Glaisher. (Paper printed at p. 258.)

The President proposed a vote of thanks to Dr. Gayer for his
paper, and also to Mr. Glaisher for persuading him to go on with
that kind of study, and for reading the paper to them on that occasion.

VOL. XV. x

284 PROCEEDINGS OF SOCIETIES.

The photographs were certainly very fine, and although it would be
invidious to say they were the finest they had seen, remembering how
many beautiful specimens they had received from Dr. Woodward, yet
he was sure all would agree with him that these photographs of
Dr. Gayer were very fine ones, and if he went on with that kind
of work they should be very glad indeed to hear of his further success,
and to see the results at some future time. He had not himself
attempted photography of this kind, except with powers of 9 or 10
linear, but he knew quite enough of it to enable him to admire the
very excellent work which Dr. Gayer had produced.

Mr. Glaisher said that the President had touched upon rather a
delicate point in mentioning what had been done by others, and he
had himself made use of this in urging Dr. Gayer to persevere ; he
had told him that Mr. Woodward was going so far ahead of us in this
respect, that he was bound to do his utmost to produce work of the
highest merit, especially as he was going to a clearer atmosphere and
brighter sun than we possessed at home.

Mr. Slack said there was one feature about these photographs.
which appeared to him very remarkable. If they considered the extent
of power to which the objects were magnified, it was surprising how
very small the beads appeared, even when looked at with a magnifying
glass. This he thought showed in a high degree the excellence of
the work, as any defect in the objective or method exaggerated the
size of such objects. These were taken with Powell and Lealand’s
yth. With regard to the holes mentioned by Dr. Gayer, and the
existence of which was said to be confirmed by the appearance of the
fractures, he could but observe that wherever a fracture was seen to
have taken place, it clearly occurred between the rows of beads, and
in each case the beads were seen to form projections all along the
terminal portion of the fracture; so that it was only necessary to look
at Dr: Gayer’s own very beautiful photographs to see that what he
said about the holes was not confirmed.

Mr. Charles Brooke had noticed that wherever a fracture was
shown in the photographs, the row of beads on either side, and between
which the fracture had taken place, was most conspicuous.

Mr. Glaisher, in reply to the President’s inquiry as to the disposal
of the photographs, said that he had no limit in the matter, and he
should be happy to hand them over to the keeping of the Society.

The thanks of the meeting were unanimously voted to Dr. Gayer
and Mr. Glaisher.

A paper by Dr. J. J. Woodward, “On the Markings of the Body-
scale of the English Gnat and the American Mosquito,” was read by
the Secretary, and some photographs in illustration of the subject
were handed round for the inspection of the Fellows. Some notes
upon Dr. Woodward’s remarks, by Dr. Anthony, were also read to the
meeting. (See pp. 253 and 256.)

The President proposed the thanks of the Society to Dr. Wood-
ward and Dr. Anthony for their papers, and remarked that the more
they looked into these questions, the more they began to doubt the
existence of some of the objects which they saw, and when they used

PROCEEDINGS OF SOCIETIES. 285

high powers it became a question of great difficulty how to interpret
appearances. In the instance before them the drawings of Dr. Anthony
really seemed to show the scale as they imagined it ought to be, but
on turning to the photographs they found that these notions were not
borne out. Extreme caution was necessary in deciding what really
existed. Accurate knowledge of the laws of light and careful induc-
tion alone could enable them rightly to approach the subject.

Mr. Slack said he should like to ask how far they might rely upon
these appearances? If he understood Dr. Woodward rightly, a longi-
tudinal section of the scale would give a wavy line, and if they sent
a ray of light across a number of the ridges they would certainly get
diffraction lines. But such diffraction lines would not absolutely dis-
prove the existence of beads. The questions of structure might be
approached by their comparative anatomy, beginning with the easiest
scales and working up towards the more difficult ones. He thought
that if Dr. Woodward could make two, three, or four rows appear, by
letting the light fall at different slants, there would be strong
evidence in support of his idea; but when they looked at his photo-
graphs they did not find there that exact arithmetical proportion
which his paper seemed to indicate.

Mr. Charles Brooke remarked that none of the photographs
appeared to present anything like it.

Mr. Blake inquired if Mr. Slack could explain how the cross lines
could be produced by diffraction ?

Mr. Slack said that Dr. Woodward assumed that there were cross
ridges, but that they were not beaded.

The Secretary said they had also received a short communication
from Mr. Stodder on the subject of Frustulia Sawonica, Navicula
rhomboides, and Navicula crassinervis. This was read to the meeting,
and upon the motion of the President the thanks of the Society were
voted to the writer. (See p. 265.)

Mr. Charles Stewart called the attention of the Fellows to an
exceedingly remarkable little organism which was exhibited in the
room by Mr. Badcock, who would be very glad to know what it was.
It was an oval thing of considerable size, microscopically speaking—
about as large as a small pin’s head—and looked something like a
gigantic Paramecium, covered with cilia; and the question was
whether it was a bond fide adult, or only the larval form of some
creature. Possibly some of the Fellows of the Society might be able
to identify it.

The President's Soirée.

On the 21st ult. H. C. Sorby, Esq., F.R.S., President of the Royal
Microscopical Society, gave an admirable soirée to the Fellows of
the Society and other invited guests, including a numerous gathering
of ladies. The authorities of King’s College kindly threw open the
great hall and an extensive suite of rooms and galleries, one on the
first floor being devoted by Mr. Sorby to a very liberal commissariat,
arranged with the manciple. The entrance hall and staircase were
decorated with fine specimens of palms and flowers; the large hall

bare

286 PROCEEDINGS OF SOCIETIES.

and libraries wére supplied with microscopes, and a lecture theatre
occupied at intervals by Dr. Hudson, Mr. Tisley, and Messrs. How.
This soirée differed from ordinary entertainments of a similar
character, by the unusual care taken to secure objects of scientific
interest as well as of beauty. The President contributed a remarkably
fine collection of slides of minerals, rocks, and meteorites, exhibited
by Messrs. Ross, Beck, and Crouch, as mentioned in the following
synopsis; also a number of micro-spectroscope objects, exhibited by

Mr. Browning.
SYNOPSIS.

ANIMAL KINGDOM.

Renuline, &c., from the Coralline Oolite
Polyeystine ; and spines of Starfish
Hunting Spider with large eyes
Ovarian tubes of Cidaris ; re
Sponge spicules; Labaria hemispheri ica ..
Forms of Arenaceous Foraminifera
Larva of Orgyia antiqua

Microscope and apparatus illustrating Nachet and Hayem’s
mode of estimating the number of red blood- thee in
the blood SS

Anatomy of Octopus vuly gar is—Young Octopus in “the eg; ;
young Octopus just hatched ; palate of Octopus; pigment
cells in skin of Octopus ; crystalline lens of eye of Octopus ;
section of arm and sucker of Octopus .. :

A series of preparations of insect anatomy, including “Musca
vomitorea (Blow-fly); Nepa cinerea ci has Scorpion); 5
larvee of Lepidoptera, &e. Sec mentale a3) ae

Elytron of Pachyrinchus, &e.

Pigment in tail of Poggé

Blood of Congo Snake ;

Vertical section of human cerebellum, injected ..

Section of Ammonite, seen with polarized light ..

Section of liuman muscle

Section of eye of Moth;

Frog, ditto ;

Ascidian Tadpoles ; transverse section of Doris gracilis 5 see
mental organs of embryo of Torpedo

Slide of 100 Foraminifera from the Dee

Sections of eyes of Tiger Beetle and Moth.. ..

Renuline from the Calcareous Grit, shown along “with Mr.
Blake’s specimens :

Young Echinus; eggs of insect on a “feather ; ‘shells of Fora-
minifera ; section of Echinus spine, &e.

Section of sciatic nerve, stained

Numerous forms of Itch Mites

Various mounted objects

Section of bone of Elephant be

Section of Seychelle Cocas de Mer

e

lung of Frog, ‘injected ; “drum of ear of

VEGETABLE KinGpom.
Crystals in plants
Fruit of marine Algze
Moss capsules .. =. .
Sections of various woods
Specimens illustrating the potato disease
Pleurosigma angulatum, sth objective ..
Batrachospermum moniliforme AG
Valisneria, circulation in, with ath

Blake, J. F.
Crisp, J. S.
Fitch, F.

Fox, C. J.

Gray, Dr. W. J.
Hailes, H.
Harris, E.

Lawson, Dr.

Lee, Henry.

Loy, W. T.
Melntire, 8. J.
Manners, G.

Matthews, Dr. J.
Richards, E.
Roberts, J. H.

Sanders, Alfred.
Shepheard, T.
Smith, J.

Sorby, H. C.

Stewart, Charles.
Ward, F. H.
West, Tuffen.
Wheeler, Edmund.
Williams, J. R.

”

Beeby, W. H.
Carpenter, Dr. A.
George, E.
Sigsworth, J. C.

A aes Smith, Worthington G.

Swift, Mr.
Vinen, P. H.
Lealand, P. H.

PROCEEDINGS OF SOCIETIES.

Livine OBJECTS.
Macinularia;and: Meli¢erta;>” 2.1) 28) ae Sets aloe Pees
Volvox globator ..
Conochilus volvox

Pond. fo Re eh Ta ae
Medusayee ee arid: TOA OR Wes) REL ese
Planaria .. Sepa 5 Geese tA gd ies

Conochilus volvor

Corethra plumicornis larva; and Lophopus cr ystalins
EOpROpus erystalunus.. o. «s -*ts ** ee See
Fredricella 56806

Pond life

MINERALS, ETC.

Boiling of carbonic acid in fluid cavities of rubies and sapphires

Fluid cavities in quartz, topaz, and tourmaline, showing the
alternate pene of carbonic acid into a liquid and into
agas .. se 5 -

Organic remains in a diamond

Crystals of gold 2

Hypersthene, seen with polarized light

Carbonate of lime in carapace of Prawn

Microscopical sections of rocks

Various specimens of minerals, rocks, and meteorites, shown
with 12 microscopes lent by Ross .._..

Specimens illustrating the application of the microscope to
blow-pipe chemistry, shown with 12 microscopes lent a
Crouch

Microscopical sections of iron and steel, shown with 12 micro-
scopes lent by R. and J. Beck meh aed bats

Large specimen of Iceland spar

Coal nodule Bie ete -

New APPARATUS, ETC.

Detached lever eeeeentont in motion under Binocular Micro-
scope ..

New fern of Stephenson’ 3 Erecting Binocular Microscope -

Ditto ditto ditto adapting the
principle to the Jackson model

Binocular Microscope, the stage fitted ‘with mechanical adjust-
ment, and provided with new centering adjustments by
which the rotation of the stage can be instantly rendered
perfectly concentric with any objective

New form of apparatus and transparencies for showing drawings
of microscopical objects in a dark room :

New apparatus for measuring the wave-length position of
pelporpmon bands in spectra ..

A {oth object-glass, by Hoviee, shown with a highly magnity-

“Sng eye-piece .. Sc

SPecTRUM APPARATUS, ETC.
Diffraction Spectroscope
Various specimens illustrating the ‘application of the Spectrum
Microscope to mineralogy, biology, De shown with 12
instruments lent by Browning 1G te Bre:

DRAWINGS, ETC.
Drawings of Rotifers, &e., &e. .
Enlarged drawings of Foraminifera.
Diagrams illustrating the microscopical structure of rocks and
eC Ve le A eC ES We tr I in

287

Badcock, John.
Cocks, Mr.

Hainworth, W., jun.

Hembry, F. W.
Ingpen, J.
Lewis, R. T.
Miller, Dr.
Oxley, Mr.
Shepheard, T.

Wight, J. F.

Butler, P. J.

Hartley," W. N.
Hunt, H. B.
Makins, G. H.
Matthews, Dr. J.

Rutley, Frank.
Sorby, H, C.

”
aah ennant, Professor.

Williams, J. R.

Bate, Dr. G. P.
Bevington, W. A.

Brouning, J.

Crouch, Henry.
Hudson, Dr.
Sorby, H. C.

Tupman, Capt.

Browning, J.

Sorby, H. C.

Hudson, Dr.
Jones, T. R,

Rutley, Frank,

288 PROCEEDINGS OF SOCIETIES.

Drawings of 100 Foraminifera from the Dee .. .. «.. «. Shepheard, T.
Photographs and drawings illustrating the potato disease, and
the growth of Agarics Smith, Worthington G.

Lithographs of the microscopical structure of limestones, &e. .. Sorby, H. C.
Microscopical photographs of iron and steel oe oe eee =
Drawing made with the pigments extracted from human hair. a

Series of large diagrams illustrating the structure of various
rocks, meteorites, &c. ee ee Is BS re

Drawings of microscopic objects .. .. .. +. «1 «+ «+ West, Tuffen.

Cryptogamic studies BE lhe idle Seg oops White, C. F.

A series of photographs of the Holy Land, &. .. .. .. .. R.and J. Beck.

A series of objects exhibited by Mr. C. Stewart under the
Society’s microscopes. (See “‘ Animal Kingdom.”)

The Martin Microscope, belonging to the Society, by Mr. Slack ;
and a Reflecting Microscope on Amici’s plan, by Cuth-
bertson; also the spectacles and other apparatus used by
Robert Brown in his botanical researches.

Mr. F. H. Ward has kindly supplied the following description
of Mr. Bevington’s microscope :—The microscope exhibited by Mr.
Bevington is a modified form of stand to be used with the binocular
arrangement of Mr. Stephenson. As this binocular is always used
in one position, the axis for inclination has been done away with,
and the instrument is supported by three legs ‘firmly attached to
the rectangular casting carrying the pinion of the coarse adjust-
ment. The fine adjustment has been obtained by chasing a fine
screw on the outside of the tube which receives the objectives, and
this is acted on by a milled collar of large diameter immediately
above them. The transverse arm, which usually contains the lever
for the fine adjustment, has been done away with, and instead of
it the upright piece with the rack of the coarse adjustment ter-
minates in a cradle, in which the centres of the bodies are balanced
and secured. This cradle revolves upon a cone, which in its turn
revolves upon the conical extremity of the upright, and as the
inside of the cone is turned excentric to the outside, by causing it
to revolve the objective is carried either backwards or forwards over
the stage, by revolving the cradle itself lateral movement of the
objective is obtained, and by these means the rotating stage may be
made perfectly concentric at any time, and then fixed by means of a
screw. In the binocular of Mr. Stephenson with the usual stand
oblique illumination cannot be obtained by moving the mirror to
either side of the instrument, as the light would then fall on the
prisms at different angles, and the fields of the eye-pieces would be
unequally illuminated. Mr. Bevington has obtained the requisite
obliquity by mounting the mirror on two brass rods which slide in
two tubes, one on either side of the ring that slides up and down the
main axis. The mirror has thus a range of about two inches in an
antero-posterior direction. For centering, Mr. Bevington substitutes
a cone terminating in a fine steel point for the objective, and secures
on the stage a piece of smoked glass, or chalked wood, then revolving
the stage a fine circle is described by this point, and after adjustment
a dot only, and he believes that this is a better arrangement than any
stage adjustment. There is also a lever which is made to embrace

PROCEEDINGS OF SOCIETIES. 289

the prism box, by which a very small movement may be imparted to
it for the accurate adjustment of the prisms. There are minor details,
but these are the principal features of the stand, which is particularly
steady and free from vibration.

Mr. Browning’s adaptation of the Stephenson instrument to the
Jackson model renders it available for those who wish to use it with
a stand of that pattern. The images of the object are reflected to the
eye-pieces by two silvered flats, so carefully worked as not to injure

the definition.

Dr. Hudson’s transparencies, consisting of beautifully executed
drawings of rotifers, were illuminated from behind, and produced an
excellent effect, which was enhanced by eloquent verbal descriptions
that attracted large audiences. Mr. Tisley exhibited in the same theatre
Mr. Spottiswoode’s splendid polariscope apparatus, and Messrs. How
and Co. showed fine micro-photographs with the oxy-hydrogen
microscope.

Donations to the Library since April 5, 1876:

From
INatunessuWiceklyck Petts... sar cep ce. ae) oo eee oe eee uClELOns
Jinnah: S\\Gal ab Ate eet poe sen Mekopas Sob, bo) adn 9 ac Ditto.
Society of Arts Journal. Weekly ... Society.

The Twenty-first and Twenty-second Annual Report of the
Brighton and Sussex Natural History Society, 1874-75. Ditto.
Water-colour Drawing of Bowerbankia .. .. .. «.. « W. IT. Suffolk, Esq.

Mon. Rénard and Dr. William Osler were elected Fellows, and
Count Castracane an Honorary Fellow of the Society.

Water W. REEVEs,
Assist.-Secretary.

Warrorp Naturat History Society.

Ordinary Meeting, March 9, 1876.—Dr. A. T. Brett, Vice-
President, in the chair.

Mr. Arthur Cottam, F.R.A.S., delivered a lecture “On some of
the Simpler Methods of Microscopical Mounting,” which he illus-
trated practically by mounting objects dry and in Canada balsam,

In treating of the cements employed in dry mounting, he stated
that gum-water should be made with perfectly cold water, with a
small quantity of alcohol and a little glycerine added; that a mixture
of india-rubber, asphalte, and mineral naphtha formed the best cement ;
and that Canada balsam was not to be relied on at all, becoming
brittle.

As an illustration of mounting in Canada balsam, he mounted
some diatoms, taking a glass slide, subjecting the diatoms to a dull
red heat, placing them in a medium consisting of two parts of balsam
to one of benzole, slightly heated, and dropping on the thin glass
cover, having previously warmed the slide to prevent its cooling the
balsam suddenly, and so producing air-bubbles.

290 PROCEEDINGS OF SOCIETIES.

He stated that the chief difficulties in these simple methods of
mounting were to get rid of moisture and air-bubbles; it was more
necessary to get rid of moisture when mounting in balsam than dry,
and more difficult to get rid of air-bubbles in glycerine jelly—a
favourite and very useful medium—than in balsam.

He recommended Mr. Davies’ work, in the Society’s library, as the
best guide to microscopical mounting.

Tt was announced that field meetings had been arranged, in con-
junction with the Quekett Microscopical Club, for June 3 at Bricket
Wood, and for July 1 at Elstree Reservoir and Stanmore Heath.

San Francisco MicroscopicAL Society.

The regular meeting of the San Francisco Microscopical Society
was held on Thursday evening, April 6.

Dr. Blake placed on the stage a slide mounted temporarily with
some living specimens of phylloxera taken from the root of a vine in
Sonoma county. In addition to the smaller type of insect, which
does the injury to the vines, there was one specimen of what he stated
was the nymph form of the same, and to which he called special
attention, from the fact that in Europe this stage in the life history
of the pest is not met with till as late as July or August. He
remarked that he could detect no wings or sucker, but found several
large ova in the body, which in Europe developed into the sexual
insect, which lays a single egg, hibernating till spring. Whether the
one before the Society would have produced the mother lice, under
favourable circumstances, he was not prepared to say. Some of the
remedies suggested to the vine-growers by Dr. Blake had been tried,
but unfortunately had proved of no avail in staying the development
or ravages of this troublesome insect. It would seem from the above
that our vine-dressers must prepare for a vigorous prosecution of the
war, and that the spring campaign will open early.

In this connection it may be well to state that it appears, from
reports supplied to the French Academy, that the most efficacious
remedies for vines attacked with the phylloxera are alkaline sulpho-
carbonates, that of soda being the most effective. It is applied in
solution, and destroys the insects without injuring the vine. :

Dr. Wythe referred to the amplifiers he exhibited at the last
meeting, and stated that he had succeeded in getting excellent defini-
tion with them, when used with very high powers; and further, that
he had adapted the same to his Crouch binocular. A new illuminator
was described by him, and which he had constructed with a right-
angled prism, a plano-convex lens cemented to one face, and an ordi-
nary French triplet attached to the other side, at a-point near the
angle. This gave him, by the slightest tilt out of a line perpendicular
to the object, an extreme obliquity of light, and which was at the
same time entirely achromatic.

Mr. Charles Stodder, of Boston, wrote the Society some facts con-
cerning the ,},th objective of Tolles.

(. o>)

INDEX TO VOLUME XV.

A.

ABERRATION, on the Characters of Sphe-
rical and Chromatic, arising from
Excentrical Refraction, and their re-
lations to Chromatic Dispersion. By
Dr. Royston-Pigort, F.R.S., 128.

Address, the President’s. By H. C.
Sorsy, F.R.S., 105.

Algee, Unicellular, parasitic within
Fossil Corals. By Prof. M. Duncan,
143.

Angular Apertures of Object-glasses, on

the Measurement of the. By Jabnz
Hoae, M.R.C.S., &e., 266.
AntHony, Dr. Joun, Note on Dr.

Woodward’s paper on the Markings
of the Body-scale of the Gnat and
Mosquito, 256.

B.

Bacteria, Presence of, in the Walls of
Hospital Wards, 33.
found in the Perspiration of Man,

34,

Basiant, M., on the Embryogeny of
the Flea, 140.

Beetle’s Eye, on a Mode of viewing the
Seconds’ Hand of a Watch through a
By Dr. Wuirret1, 136.

BEnnetT, ALFRED W., M.A., the
Absorptive Glands of Carnivorous
Plants, 1

Buake, J. F., on Renulina Sorbyana,
262.

Blood, the Circulation of, in the Frog’s
Lung, 142.

Corpuscles, Form and Size of the

Batrachian, 93.

Examining the, 94.

the Emigration of, 276.

— Globules in Typhoid Fever, 233.

—— Stains, Improved Method of ap-
plying the Micro-spectroscopic Test
for. By Jos. G. Ricuarpson, M.D., 30.

Brorck, M. Ernest VANDEN, on a New
Microscopic Slide, 221.

Brown, Mr. J. A., on the Measurement
of Nobert? 8 Bands, 273.

C.

Carbonic Acid, the Identification of
Liquid in Mineral Cavities. By
WatteR Nort Harriny, F.CS.,
170.

Carter, Mr. H. J., on the Difficulties
of Classification of the Spongida, 238.

Cell, a Growing, adapted for supplying
Moist Air, 198.

Cells, Structure of the Pancreatic,
observed during Digestion, 228.

Chara, Production of the Prothallus
from the Spore of, 145.

Cholera, Microscopic Examination of

® the Intestines in cases of, 142.

Collomia coccinea, the Seeds of, 145.

re by Tyndall and Bastian,

146,

Corals, Vegetable Parasites in, 93.
Unicellular Algze parasitic within
Fossil. By Prof. M. Duncan, 143.
Corpuscles, the Migrations of the White.

By Dr. Jun. Arnoxp, 34.
Correspondence :—
AxKAk&IA, 101.
BRANWELL, R., 43.
Brooke, CHARLES, 45, 201.
F.R.M. S., 48, 49.
GorDon, M. a 41,
GRIrrin, F, Ww. M.D., 95, 242.
Haserr, 18%, 95.
Hick, THOMAS, B.A., 156.
Houeues, Ricwarp, 52.
JOHNSTON, CHRISTOPHER, M.D., 44.
JONES, Professor R., 200.
Kern, R., 199.
Krrron, EF, 51, 52.
Mayatt, J., jun., 51, 97.
Morenovse, G. W., 40.
Picort, G. W. Roysron-, 100.
SHADBOLT, GEORGE, 202.
Surry, H. L., 278.
Toutes, R. B., 281.
WenuaM, F. H., 45, 46, 47, 48, 151,
241.
Crustacea,.the supposed Renal Organ
in. By Mr. A. 8. Packarp, jun.,
35.

292

Crustacean, a New Phyllopodous, 137.
Cryptogams, a New Classification of.
By Professor J. Sacus, 270.

1D

DauuincEerR, Rev. W. H., on a New
Arrangement for Centering and
Illuminating with High Powers, 165.

Diatomaceen-Probe-Platten, the Mea-
surements of Moller’s. By E. W.
Mortry, 223.

Diatoms, the Examination of Coal for,
137.

Dr. Woopwarp on the Spurious

Lines of, 144.

F.

Fish, Characters of the Slime of Phos-
phorescent, 270.

Fishes: the Roots of the Spinal Nerves
in Elasmobranch Fishes, 235.

Flea, the Embryogeny of the.
Ba sBianl, 140.

Foraminifera, Remarks on the, with
especial reference to their Varia-
bility of Form, illustrated by the
Cristellarians. By Professor RuPERT
Jongs, F.R.S., 61, 200.

of the Chalk, Instructions for
Cleaning, 241.

Frustulia Saxonica, Navicula rhom-
boides, and Navicula crassinervis.
By Cuarues Stopper, U.S.A., 265.

— —— H. L. Smita on, 278.

—— —— Further Notes on.
J. Hicks, M.A., 122.

By M.

By W.

G.

Ganglia, Relations of Nerves to, 228.

Gaver, Surgeon-Major E. J., Notes on
Micro-photography, 258.

Gites, G. M., Avoiding the Heliostat
in Micro-photography, 26.

Gland, Nerve-supply to the Thyroid,
231.

—— the Minute Anatomy of the Thy-
roid, 232.

Glands, the Absorptive, of Carnivorous
Plants. By A.trrep W. BENNETT,
MA. Ie .

Glycerine, the best Cement with, 197.

Gnat, on the Markings of the Body-
scale of the English, and the

INDEX,

American Mosquito.
WoopwakpD, 253.
Gututver, Mr. G., on the Spermatozoa

of the Petromyzon, 33.

By Dr. J. J.

Jal

Heematococcus lacustris, the Develop-
ment of, 196.

Hemoglobin, the Evolution of, 149.

HArtTLEY, WALTER Nosgt, on the Iden-
tification of Liquid Carbonic Acid in
Mineral Cavities, 170.

Heliostat in Micro-photography, avoid-
ing the use of the. By G. M. Gites,
26.

Hicxrs, W. J., M.A., Further Notes on
Frustulia Saxonica, 122.

on Zeiss’ jth Immersion,

185.

Hoae, Japez, on the Measurement of
the Angular Apertures of Object-
glasses, 266.

Hyrax, the Placentation of, 235.

If

Illuminating and Centering with High
Powers, a New Arrangement for.
By Rev. W. H. DauuineEr, 165.

Insects, the Secreting Organs of the
Alimentary Canal in, 269.

J.

JoneEs, Professor Rupert, F.R.S., Re-
marks on the Foraminifera, with
especial reference to their Variability
of Form, illustrated by the Cristel-
larians, 61, 200.

L.

Lactate of Silver as a Colouring Agent.
By M. Arrrow, 38.

Lens, Browning’s Platyscopic, 37.

Lepas fascicularis, the Development of,
and the ‘‘ Archizoéa” of Cirripedia.
By Dr. R. von WILLEMOES-SvuuM, 137.

M.

Micrococcus and Bacteria, Presence of,
in the Walls of Hospital Wards, 33.

Micro-photography, Notes on. By Sur-
geon-Major E, J. Gaymr, 258.

INDEX.

Microscopy at the American Associa-
tion, 278.

Mollusks, the Development of Gaste-
ropod, 238.

Morenovss, Mr. G. W., on Silica Films
and the Structure of Diatoms, 38.
Morty, E. W., of Hudson, Ohio, the
Measurements of Moller’s Diatoma-

ceen-Probe-Platten, 223.

Mosquito, on the Markings of the Body-
scale of the American. By Dr. J. J.
Woopwarp, 253.

Mounting, a Concentrated Mode of,
151.

Mushroom Tribe, Reproduction in the.
By Wortuineton G. Suiru, F.L.S., 6.

N.

Navicula rhomboides, Note on the
Markings of. By Dr. J. J. Woop-
WARD, 209.

Nervous System, a New Mode of
Colouring Sections of the, 228.

Nobert’s Bands, the Measurement of.
By Mr. J. A. Brown, F.B.S., 273.

O.

Object-glasses, on the Aperture of.
By F. H. Wenuam, 184.

How to Measure the An-
gular Aperture of, 236.

Objectives, an Improved Method of
Numbering, 197.

— of Seibert, New Formula, 198.

Obsidian, Perlite, and Leucite, on
some Structures in. By Frank
Ruttey, F.G.S., 176.

Ostracoda, to Mount, in a Permanent
Manner, 150.

P.

PackarpD, Mr. A.S., jun., on the sup-
posed Renal Organ in Crustacea,

Paresis, State of Chord in Death from,
238

Petromyzon, the Spermatozoa of. “By
Mr. G. GULLIVER, 33.

Phylloxera, a New Form of the, 277.

Piegort, Dr. Royston-, F.R.S., on
the Characters of Spherical and
Chromatic Aberration arising from
Excentrical Refraction, and their
relations to Chromatic Dispersion,
128,

293

Plants, the Absorptive Glands of Car-
nivorous. By A. W. Brennert, M.A.,
1

— and Animals, the Relations be-
tween, 144,
— Lignin in, 234.
Postal Micro-Cabinet Club, the Ame-
rican, 240.
Potato Disease, the, 269.
Prickle-cells in the Wall of the Stomach
of certain Animals, 145,
Proceepines oF Socreries :—
Adelaide Microscopical Club, 249.
Fairmount Microscopical Society, 252.
Medical Microscopical Society, 58,
104, 247.
Memphis Microscopical Society, 60.
Quekett Microscopical Club, 59, 206,
248.
Royal Microscopical Society, 53, 56,
101, 157, 203, 244, 282, 285.
San Francisco Microscopical Society,
252, 290.
South London Microscopical and
Natural History Society, 207.
Watford Natural History Society,
289.
Prothallus from the Spore of Chara,
the Production of, 145.

R.

Ruwarp, Mons. A., 8.J., some Results of
a Microscopical Study of the Belgian
Plutonic Rocks, 212.

Renulina Sorbyana, on.
Buakg, 262.

Ricwarpson, Jos. G., M.D., Improved
Method of applying the Micro-
spectroscopic Test for Blood-stains,
30.

Rocks, some Results of a Microscopical
Study of the Belgian Plutonic. By
A, Renarp, 8.J., 212.

Ruttry, Franz, F.G.S., on some
Structures in Obsidian, Perlite, and
‘Leucite, 176.

By roeee

8.

Salpa spinosa, Egg and Bud Develop-
ment of, 146.

Sarcomas, on the Development of
Spindle-cells in Nested. By Dr.
Gowers, 271.

Saxifraga tridactylites, the Leaf
Glands of. By Mr. J. C. Drucs, 33.

Sections, on Staining and Mounting
Wood. By M. H, Srinzs, 133,

294

Silica Films and the Structure of
Diatoms. By Mr. G. W. Morenovse,
38.

Slide, a New Microscopic. By M.
Ernest VANDEN BROECK, 221.

Smiru, Worruineron G., F.LS., Re-
production in the Mushroom Tribe, 6.

Snakes, the Development .and Succes-
sion of the Poison-fangs of, 229.

Soirée, the President of the Royal
Microscopical Society’s, 285.

Sorsy, H. C., F.R.S., &., the Presi-
dent’s Address, 105.

Spongida, Difficulties of Classification
of the, 238.

Stage, an American Adjustable Con-
centric, for the Microscope, 150.

Srizzs, M. H., on Staining and Mount-
ing Wood Sections, 133.

SropvER, Cuartes, U.S.A., Remarks
on Frustulia Saxonica, Navicula
rhomboides, and N avicula crassi-
nervis, 265.

db

Tissues, New Colouring Agents in the
Examination of the, 196.

— the Action of certain Colouring
Matters on the, 149.

Tomes, Mr. Cuares, on the Develop-
ment and Succession of the Poison-
fangs of Snakes, 229.

Turn-table, an Improved Form of Cox’s,
94.

INDEX.

U.
Utricle, the Primordial, 146.

Wz:
Volvox, the Rotifer within the, 236.

Ws

Wenuam, F. H., on the Aperture of
Object-glasses, 184.

WuitteE., Dr., on a Mode of viewing
the Seconds’ Hand of a Watchthrough
the Eye of a Beetle, 136.

WILLEMOEs-SuHmM, Dr. yon, on thie
Development of Lepas fascicularis
and the “ Archizoéa” of Cirripedia,
137.

Woopwarp, Dr. J. J., Note on the
Markings of Navicula rhomboides,
209.

on the Markings of the Body-
scale of the English Gnat and the
American Mosquito, 253.

ihe

Zeiss’ th Immersion, on,
Hick1e, M.A., 185.

By W. J.

END OF VOLUME XY.

LONDON:

PKINTED BY WM. CLOWES AND SONS, STAMFOKD STREET AND CHARING CKOb5.

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