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THE MONTHLY
MICROSCOPICAL JOURNAL:

TRANSACTIONS

OF THE

ROYAL MICROSCOPICAL SOCIETY,

AND

RECORD OF HISTOLOGICAL RESEARCH

AT HOME AND ABROAD.

EDITED BY

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

VOLUME XVII.

1B RAR
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we
REW YORK
BOTANICAL ~

Carpe’

LONDON:
HARDWICKE ann BOGUE, 192, PICCADILLY, W.

MDCCCLXXVII,

The MonthlyMicroscopieal Journal.Jan.1.1 877. bs & CLXV.

Foams
vt ietilt (EEL

ANN

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W West& Co lithe.

Identity of N.crassinervis. F. Saxonica and N rhomboides.

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The Monthly Microscopical Journal.Jan.1.1377. Pl Cis
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W.HDoallinger dd ad nat. 7 WWest& Co. ith. ©

Identity of N .crassinervis. F Saxonica and N rhomboides.

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REW YORK

THE BOTANICAL

MONTHLY MICROSCOPICAL JOBRNAL.

JANUARY 1, 1877.

”

I.—On “ Navicula crassinervis,” “ Frustulia Saxonica,” and
Navicula rhomboides, as Test-objects.

By Rev. W. H. Datiincer, V.P.R.M.S.
(Read before the Royvau Microscopican Society, December 6, 1876.)
Puates CLXV. anp CLXVI.

Amonest competent authorities there appears to be no longer
any dispute as to the true relations of the diatoms that have
hitherto received the separate designations in the above title.
Professor H. L. Smith of America, and Mr. Kitton of our own
country, doubtless two of the most competent living authorities,
are agreed that they are but three names for the same species ; for
both “ N. crassinervis” and “ F'. Saxonica” have no real existence,
being but forms of NV. rhomboides.* But the vicissitudes through
which opinion and conviction have passed, in less than two years,
as precursive of this valuable conclusion, are interesting. In May,
1875, Mr. Hickie, without the slightest doubt, declared F. Saxonica
and N. crassinervis to be distinct species; and his conviction was
reached not hastily, but after a study of the literature of the
subject, after a careful investigation of his own collection of
F. Sazxonicas, which was “a pretty extensive one,” and after ex-
amining it, as a form properly entitled to its name, in company
with Dr. Rabenhorst, “ both the discoverer and namer of the diatom
in question.” + Besides which, he gives evidence, then clearly
satisfactory to his own mind, that these three diatoms must be
different, from the fact that to properly resolve them, they must
be each placed differently in relation to the source of light.t
But the great end he had in view was, to correct what he held
to be a misconception on the part of Dr. Woodward as to the exist-
— ence of longitudinal strie on “F'. Saxonica”; which Dr. Woodward
© considered to be illusory, and which Mr. Hickie declared to be
Le real; and the reality of which he contended was not only assured
r+ by the evidence he brought, but by their having been perfectly
i photographed by Herr Seibert.
c» Lo this, with his usual thoroughness, and the aid of his match-

Lu]
CG * ‘M.M. J? vol. xv. pp. 278-281. + Ibid. vol. xiv. p. 33. t Ibid. p. 35.
VOL. XVII. B

2 Transactions of the Royal Microscopical Society.

less skill in micro-photography, Dr. Woodward replied ;* reaffirming
his conviction that the “longitudinal strie of Dippel,’ and, in
addition, those announced to have been seen by Mr. Hickie, were
due to diffraction and interference; the spurious lines produced by
which, he declared and proved, could be as readily photographed as
real ones. Some beautiful photographs in support of this were
sent ; and certainly to the skilled observer there can be no question
that in the case of the frustules photographed by Dr. Woodward
(and excellently reproduced in this Journal +) the lines photographed
are spurious. Further, whoever has taken note of Dr. Wood-
ward’s skill in manipulating test and other difficult objects, will
want no assurance, that in reference to the frustules in the photo-
graphs, if they could not be developed by Dr, Woodward, the
probability is that they could not be developed at all. But this
observer adds a note of extreme significance in this relation ; for he
says, “ At the same time I shall be very glad if he (Mr. Hickie)
can convince me, by satisfactory evidence, that this belief is
erroneous, for analogy inclines me towards the opinion that in both
Frustulia Saxonica and Amphiplewra pellucida the striz are
really rows of beads, as is so easily to be seen in Navicula
rhomboides, and that consequently we ought to be able to see
longitudinal strize when the illuminating pencil has the proper
direction, if only our glasses had the requisite defining power.”
The italics are mine, but they show the sound and unbiassed view
of the writer.

A rejoinder is now given by Mr. Hickie.} In this occurs a
letter from Dr. Rabenhorst, declaring the longitudinal striz of
F, Saxonica to be real, and affirming that “if Dr. Woodward main-
tains that Frustulia Saxonica is identical with Navicula eras-
sinervis we must suppose that he is ignorant of one or other of
them.” At the same time Herr Seibert’s photographs of the
longitudinal as well as the transverse striz of a reputed “ #. Saa-
onica” were presented to this Society for inspection. At the
discussion which followed the reading of this paper it was affirmed
that the photographs were simply indistinguishable from “ coarse
Rhomboides,’ § and in both the paper and the discussion Mr. Hickie
retracted “a previous erroneous statement,” and confessed that he
was unable to ‘‘ state where Frustulia Saxonica ends and ‘ small’
Rhomboides begins.” || They were in fact identical. But he still
maintained that ‘‘there was a very great difference between them
and Crassinervis.” 4]

After this, in a subsequent paper,** Dr. Woodward definitely
proved that Herr Seibert’s photograph, purporting to be “ F. Saa-

* ‘M. M. J.’ vol. xiv. pp, 274-281. f Ibid. + Ibid. vol. xy. p. 122.

§ [bid. vol. xv. p. 103, || Ibid. p. 127. | Ibid. p, 104.
** Thid. p. 209.

On “ Navicula crassinervis,” &e. By W. H. Dallinger. 3

onica,” was, what it had been by some competent judges affirmed
to be, ‘a coarse form of Rhomboides.”’ Mr. Charles Stodder then
adds a concise note,* giving reason and authority for believing that
both N. crassinervis and F. Sawonica are but forms of N. rhomb-
otdes; and Dr. H. L. Smith’s most valuable and conclusive letter
follows ;¢ and in this it is shown that not only is there identity
between the three diatoms in question, but that all important
authorities, Rabenhorst excepted, are agreed in the admission of
that identity. To this letter Mr. F. Kitton, who had been requested
by Professor H. L. Smith to revise the proofs, takes the opportunity
of stating that he fully agrees “that the genus Frustulia should
be abolished ;” and he is also of opinion “that Navicula cras-
sinervis 1s only a form of N. rhomboides.” He adds, “ I may
also state that my friend Mr. Hickie is of the same opinion.”
Clearly therefore Mr. Hickie’s conviction of the “very great dif-
ference” existing between N. rhomboides (into which F. Saxonica
had now been fused) had been overcome. The reasonings or facts
which accomplished this in Mr. Hickie’s case are not given us; but
his frankness and candour are sufficient evidence of the scientific
spirit in which his inquiries were conducted.

So far, it is clear, that these three diatoms are, on the best
authority, accepted as mere conditions of the one form, N. rhomb-
otdes. ‘The reasons for this decision have relation to morphology
and development, quite as much as to the characteristics of the
silicious skeleton with which the microscopist is more generally
concerned. With the former of these reasons I may not concern
myself, but receive them thankfully from competent authority.
But with the latter facts I will venture briefly to deal.

Nothing up to this time is finally before us, as to what kind of
“resolution ” these various conditions of Rhomboides may be
expected to yield, or what their real value, as tests, is.

My first acquaintance with this diatom was made some eight or
nine years since. It had lain in my cabinet for some years before
this: but some exquisite specimens prepared and mounted by
L. Hardman, Esq., were courteously given me by him, and I did
my best at that time with them. They were what I presume have
been called ‘‘ small Lhomboides” ; for the largest of them taxed the
power I then possessed, to develop their transverse striz sharply
and well, with a good English 1th, and the smaller of them were
so fine, as to resist all the manipulative skill I then possessed with
a ysth, and some of the minute ones, even with Powell and
Lealand’s y';th (dry).

Coming from so excellent an authority on diatoms as Mr.
Hardman, I accepted these as normal specimens of the species ;
and as my manipulative skill increased with practice, and my

* “M.M. J? vol. xv. p. 265. + Ibid. p. 279.
B 2

4 Transactions of the Royal Microscopical Society.

battery of lenses became improved, I was enabled to resolve into
hemispheres all the larger, and most of the medium-sized ones, and
eventually to consider myself master of the resolution of this
diatom ; a work which I accomplished not for its own sake, but
merely to have a given set of marked tests, of known value to
myself, for the sake of future comparison. When therefore the
value of “ F. Saxonica,” as a test for high powers, was announced,
I proceeded at once to procure it. My first specimens were got
from London ; but to my surprise the forms sent under this name
were neither more nor less than the medium-sized frustules of my
now well-worked specimens of N. rhomboides. I of course con-
cluded that there was an error in naming, and at once wrote off to
two other sources for the form I required. ‘To my great vexation,
these were merely repetitions of what I had received before, one of
them containing really coarser specimens than any I could find on
Mr. Hardman’s slides of N. rhomboides. Determined to obtain the
right frustules, I wrote to an English friend, then in Germany, —
and was favoured with specimens, slightly smaller, but in every
sense identical with those supplied from English sources. I failed
to discover a single difference between them. I could striate, or
resolve them into dots, precisely as I did my N. rhomboides. Their
midribs—a very characteristic feature—were precisely like Rhomb-
oides, and their general contour varied, as N. rhomboides varies,
some frustules having an inclination to an obtuse angle in the
centre of the margin, while others preserve in their margin a
continuous curve.

I had never made the natural history of diatoms a study; so
the inference I was obliged to make was, that there must be some
morphological or developmental difference between these diatoms
which justified the difference of name: but as tests I determined
that there was certainly no difference between them.

When I first obtained N. crassinervis, my difficulty was almost
as great; for although the frustules on the slides so named were
certainly much smaller than the majority of frustules on my speci-
mens of Lhomboides, still I could find some almost, if not quite, as
small; and I could detect, in an examination of a number of
specimens, nothing that had not its complete equivalent in the
frustules of Rhomboides. I felt therefore bound to conclude that,
as test-objects, these three separately named diatoms were merely
Rhomboides of various sizes, and therefore, generally speaking, of
greater or less difficulty in “ resolution.” I reached this conclusion
nearly three years since, but as it was an opinion formed on the
silicious frustules alone, and had no connection with the natural
history of the form, I merely set it aside for what I considered it
worth. But as competent authorities have now—fully knowing
the nature of the plant—determined that the three forms in

On “ Navicula erassinervis,’ &e. By W. H. Dallinger. 5

question are but conditions of the one form (Ahombozdes), it appears
to me that some interest attaches to the fact that proofs of this
may be obtained by a serial study of the silicious frustules, from
the smallest or most dwarfed, to the largest or most developed ; and
that such a study brings out plainly what value should be attached
to this diatom as a test-object.

I have now a very considerable collection of these forms,
gathered from many sources, and through the courtesy of many
friends; but I rarely find, amongst the very finest and minutest of
them, any frustules that will not yield complete resolution into
hemispheres, with Powell and Lealand’s “new formula” }-inch
objective (immersion), with one or other of the methods of illu-
mination I now employ; using as the source of light a broad-
wicked paraffin lamp with the flame turned edgeways to the con-
denser. Unfortunately time has never been sufficiently at my
disposal, to enable me to make micro-photography my servant in
study. But as the objects I have concerned myself with during
the greater part of my life as a microscopist, have been swiftly
moving vital ones, in the portrayal of which even photography
could have been of no service, I have been obliged for some years
to cultivate, with as much care as I could exercise, an accurate and
delicate use of the pencil, in fixing permanently the images of
objects which the microscope revealed. I believe in this instance
its aid may be called in with some service.

Having satisfied myself of the absolute similarity, in ultimate
structure, of all the modifications of what we shall hereafter know
as N. rhomboides, it appeared to me advisable to take one of the
smallest of the forms hitherto labelled “ N. crassinervis,” and find
the least magnifying power that would perfectly resolve it, and
then employ the same power, and the same mode of illumination,
on a series of the increasingly larger forms, until the extremely
coarse ones were reached. In this way the identity of the ultimate
structure in every developmental condition would be seen.

The power necessary to resolve completely the smaller forms of
the “ N. crassinervis” in my cabinet was 800 diameters (obtained
with the }th above referred to). The figure marked A, Plate CLXV.,
represents the result. The brilliant definition obtained by the lens,
rendered much more apparent the “resolution” than the most
delicate drawing or photograph could do; but the drawing given
is a careful rendering of the effect. It will be seen that some
portion of the striae (transverse) are seen on the left-hand side of
the midrib: but they are seen perfectly on the right-hand side;
and in the upper half of it, resolution into dots, or hemispheres,
placed in rectangular rows, is, in a good light, clearly visible.

Of course, it is not pretended that enumeration of striz, and
so forth, could be effected from this or the following drawings, as

6 Transactions of the Royal Microscopical Society.

from a photograph. But they accurately represent the general
facts.

I next took a frustule of the same (reputed) form (“ N. crass¢-
nervis”) which was of an average size, and placed it under the
same lens, with the same illumination. The result is given at B,
which represents the frustule magnified as before—800 diameters.
Precisely the same “resolution” is given; but faint longitudinal
lines are seen, in addition to the far more plainly visible hemispheres,
placed precisely as in A.

An average specimen of what was then labelled “ F’. Sawonica,”

was now made to replace the above, all the conditions remaining
intact. The drawing C, magnified 800 diameters, represents the
result.. I have obtained more general “ resolution” into hemi-
spheres than is here shown; but the specimen is typical, and I
preferred to retain it. Transverse striz will be seen to be uni-
versal; longitudinal striz are here and there faintly visible, and
the rectangular rows of hemispheres are unmistakably manifest.
Finally, a fair specimen of what I had long known as N. rhomb-
oides was placed on the stage of the instrument, and, everything
remaining as before, was examined. The result — magnified as
before—is given at D. What was now aimed at was not to get
the largest surface of hemispheres, but to get such a general result

as would show the exact correspondence, in ultimate structure, of

the preceding forms with this. The transverse striz, the longitu-

dinal striz, and the rectangularly placed rows of hemispheres, are

all most distinctly seen.

But during the last three years some remarkable specimens of
Rhomboides have come into my hands—specimens in which the
frustules reach an immense proportional development ; and in which
the striz, or rows of hemispheres, are very much coarser in rela-
tion to Mr. Hardman’s coarsest frustules than the -latter are in
relation to the finest and smallest of the forms so recently called
“ N. crassinervis.” The largest of these have been found by me in
some mountings received from a friend, and marked as having
come from “Cherryfield, America.” The variation in their sizes,
on the same slide, is very great, and the consequent difficulty of
resolution ; but I selected one of the larger forms, and employing
the same illumination as in the instances given above, put on the
4th immersion of Powell and Lealand (new formula) in place of the
4th, and worked up to 600 diameters. The result is given at E, Plate
CLXYVI., which may be taken at once as the interpreter of all the rest,
and the witness of their oneness. The striation in this case is every-
where resolved into rows of hemispheres, placed in rectangular
order ; and I know of few more beautiful objects in “still” micro-
scopy than this. The frustule is of exquisitely perfect form,
slightly tinted with yellow-brown : the hemispheres are everywhere

On “ Navicula crassinervis,” &e. By W. H. Dallinger. 7

sharply and clearly separate, and the continuity of this is unbroken
from end to end.

If this form be studied with a good } (dry) of an angle of
aperture of about 95°, and if the stage of the microscope be
moderately thin, and all sub-stage gear be taken away, and the light
from a good lamp condensed by a “ bull’s-eye” of about 5-inch
focus be sent in at an angle of about 30° with the under surface
of the slide, and the image of the flame be focussed on the centre
of the object, this specimen of Rhomboides can be exquisitely
resolved, on a black ground, with a third, or even a fourth eye-
piece; the frustule itself, especially if seen amongst brilliantly
white diatoms, assumes a pale sapphire tint, and the hemispheres
with skilful management are beautifully developed.

Taking these facts together, then, and guided by the decision
announced by Professor H. L. Smith and Mr. Kitton, we may
safely conclude that N. rhomboides is a diatom very permanent in
its general form and characteristics, but eatremely variable in its
size, and the tenwty of the ultimate structure of its silictous
Srustules.

But from this, a corollary inevitably follows. N. rhomboides
ig a most uncertain and unreliable test. Unless the same mount-
ing, and in many instances the same frustule, be used, in testing
the capacity of a given lens, the most incongruous issues may
result. To be told that a certain glass will resolve “ N. rhomb-
oides,” may mean that it will resolve E, Plate CLXVL., or that it
will resolve A, Plate CLX V.—quite a different result, and no guide
as to whether A’s or B’s lens 1s better or worse than mine of the
same power, unless the same slide of frustules be employed.

To those accustomed to the use and comparison of diatomaceous
test-objects for practical purposes, this is no new inference, as
Mr. Kitton has recently so profitably told us.* But it is so palpable
an instance that it may carry conviction.

DESCRIPTION OF PLATES CLXY. AND CLXVI.

Fig. A.—WNavicula crassinervis x 800 diameters, showing rectangularly placed
hemispheres.

B.—Ditto, ditto, a larger form similarly magnified.

C.—Frustulia Saxonica, magnified by the same power, and showing similar
structure.

D.—A small form of N. rhomboides, also magnified 800 diameters, revealing
the same structure. :

E. —-A very large form of NV. rhomboides from “ Cherryfield,’ America, showing
a corresponding structure, with a magnification of 600 diameters.

* <M. M. J.’ vol. xiv. p. 45.

8 Transactions of the Royal Microscopical Society.

Il.—A Stage Incubator. By H. A. Rerves, Assistant-Surgeon
and Teacher of Practical Surgery, London Hospital.

(Taken as read before the Royau Microscopicau Society, December 6, 1876.)

Ir is much to be desired that the various processes of elementary
tissue change and of development and growth should be observed
under the microscope. To this end I have devised the followmg
simple apparatus, which, as will be seen, is a modification of the
Stricker-Sanderson hot stage, with the gas-tubes omitted. The
central cell, which is larger and ovoid, is only excavated to a depth
sufficient to allow of a pigeon’s, or smaller egg, as of sparrow,
canary, &c., being admitted, and is continuous beneath the egg to
permit of the circulation of the hot water. The accompanying
woodcut, Fig. 1, represents a section of the incubator, the inter-

rupted line being the cover-glass, and E the egg with its shell and
fibrous covering removed sufficiently to expose the blastoderm.
The space between the egg and the apparatus should be packed
with cotton wool to retain the heat, and to prevent injury to the
egg. If found necessary a little sulphuric acid can be dropped on
the wool to prevent the condensation of vapour on the cover-glass.
Page’s gas regulator should be employed to keep the feeding water-
containing vessel at a constant temperature, which can be watched
by the attached thermometer. I hope that this simple instrument,
permitting, as I believe it will, of the observation of the blastoderm,
as an opaque object, for hours and days, may be of solid service in
embryology.

It is obvious that by increasing the size of the instrument, a
hen’s or duck’s egg could be accommodated ; and if the excavation
for the egg were carried quite through the centre of the incubator
—hbut not at the sides—and enough of the shell removed from the
lower side of the egg, I think the blastoderm and yolk could be

Notes on Pollen. By Worthington G. Smith. 9

studied as transparent objects, provided a strong light and a good
condenser were used,

4 inches

Fig. 2 represents the entire instrument, which is made by Mr.
Hawkesley, of Oxford Street.

III.—WNotes on Pollen. By Worruineron G. Surru, F.LS.
Puates CLXVIL., CLXVIIL., CLXIX., anp CLXX.

THE following notes on pollen have reference alone to the external
form of a few typical pollen-grains as seen under the microscope.
The formation of pollen within the mother-cells, the minute ana-
tomical structure of pollen, and the nature of the pollen-tube, will
not here be touched upon. A few words may be written on these
latter subjects on another occasion.

The accompanying illustrations are all engraved direct from
nature to one uniform scale; all the figures are enlarged 400
diameters. A mere glance will show how extremely pollen-grains
differ in size, in form, and in external marking: they also differ
greatly in colour, but from necessity on this occasion the colours
cannot be conveniently reproduced. In nearly every instance the
peculiar markings or reticulations on the cells are only partly indi-
cated in these engravings (to save labour) : for instance, in Fig. 5 the
pattern is complete, whereas in 13 and 14 the peculiar markings are
left unfinished for the reason mentioned. Pollen-grains also differ
very much from each other in their viscidity or dryness of surface,
and in their density or translucency. As a rule, pollen-grains are

10 Notes on Pollen. By Worthington G. Smith.

fairly constant in size and form in each botanical species of plant,
but in long-cultivated garden varieties and hybrids the pollen shows
a great tendency to vary.

The true form of pollen can only be seen when it is perfectly
fresh and dry, at the time when it is naturally shed from the
anther. If placed in water or glycerine for microscopical examina-
tion, the shape of the grain at once changes, commonly to a
spherical form. Sometimes on drying the grain will return to its
original shape, but more frequently it does not do so. A great
number of Bauer’s drawings, preserved in the herbarium of the
British Museum, are taken from grains which have been immersed
in fluid, and so the drawings cannot be implicitly depended upon.

Mr. A. W. Bennett suggests that plants may be roughly
divided into two classes—the class which has the pollen carried to
the stigma by the agency of the wind, and the class which receives
the pollen through the agency of insects. The first class is said, as
a rule, to have flowers without ornamental form or beauty of colour,
and unfurnished with odours ; the latter class is said to have bright
coloured and more or less scented flowers, attractive to insects.
The pollen-grain in the first class is said to be as a rule plain in
form and easily carried by the wind; in the latter spiny or fur-
nished with protuberances or furrows, to aid in its attachment to
the limbs and bodies of insects. Generalizations are always dan-
gerous, especially when made on a large scale, but in this mstance
Mr. Bennett’s suggestion is undoubtedly supported by a large
number of facts; there are, however, some striking exceptions.

It is never safe to judge of the character of pollen from a few
grains shaken out of a corolla, as sometimes the interior of flowers
will be found covered with pollen belonging to many different
flowers. This is caused by the visits of flies, bees, and other
insects, with pollen from various plants dusted over their bodies.
Numerous natural hybrids arise from the visits of these pollen-
dusted insects, and it is quite impossible to keep some garden
varieties distinct on this very account. The ornamental Gourds of
our gardens form a case in point.

In the genus Ginothera most of the pollens are large in size,
and the grains are more or less attached to each other by fine viscid
threads. The threads of necessity get entangled on the limbs
of insects, and so the pollen is carried about and transferred in
masses. One of the largest pollens known to us is that belonging
to nothera macrocarpa (Fig. 1, Plate CLXVII.). A second

member of the Onagrad family is illustrated in Godetia Whitneyi,

in Fig. 2; whilst a third, Clarkia pulchella, is shown in Fig. 3.
One of the smallest pollens seen by us in the Onagrad family is that
belonging to Circwa alpina (Fig.4). Associated with these pollens
in the anther it is common to find groups of free crystals or raphides.

Mouthly Microscopical Journal, January 1, 1877. PLATE CLXVII.

Ae
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MINI ITT

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POLLEN GRAINS x 400. Fics. 1 To 22.

Notes on Pollen. By Worthington G. Smith. 13

The four pollens just referred to may be considered quite typical of
the Onagracee. ‘The best marked species bear pollen which is
most constant in form, whilst in the long-cultivated garden plants,
as the Fuchsia, the pollen is always variable. When Fuchsia pro-
cumbens was reintroduced to our gardens a year or two ago by
Mr. F. R. Kinghorn, it was expected that many beautiful and
curious hybrids would be raised between this plant and some of the
better known Fuchsias of our gardens; but we pointed out at one
of the meetings of the Royal Horticultural Society that the pollen
of Fuchsia procumbens differed from every other Fuchsia pollen
known to us at that time.* Therefore the production of true
hybrids appeared to us, if not impossible, at least very improbable.
The statement of this fact was replied to by a famous horticulturist,
who said hybrids had already been obtained, and so our hypothesis
for a time fell to the ground. We waited for two years in doubt
as to these hybrids, and last July we wrote to Mr. Kinghorn to
know how they proceeded. In reply, Mr. Kinghorn immediately
and frankly wrote: “I have not succeeded in raising any hybrids
between F’. procumbens and the garden sorts, although I have tried
on a number with the greatest care.” Elsewhere in the same
letter Mr. Kinghorn remarked—* but I have succeeded in raising
a few seedlings from Ff. splendens crossed with F’. procumbens,
really intermediate in character.” Now in F’. splendens, which is
a good species, it is a singular fact that the pollen is of two forms ;
about one-third of the pollen is triangular in shape (like that of
most Fuchsias), whilst at least two-thirds is so exactly like the
peculiar-shaped pollen of F’. procumbens, that it can hardly be dis-
tinguished from it.

Triangular pollens are by no means confined to the Onagraces
family, as Fig. 5 represents the pollen of the common Honeysuckle,
Loniecera periclymenum ; Fig. 6 that of Erica tetralix ; and Fig. 7
that of a Rhododendron, R. Catawbiense. Another member of the
Erica family, Clethra arborea, Fig. 8, differs from the general
form.

Few pollens are more interesting than those belonging to the
Borage family. All we have seen are small, some quite minute,
and all are more or less shaped like dumb-bells. Fig. 9 represents
that of the common Comfrey, Symphytum officinale, Fig. 10 that
of Cerimthe bicolor, Fig. 11 that of Omphalodes linifolia, and
Fig. 12 that of Hchiwm vulgare. The latter pollen is remarkable
on account of its two lobes being always unequal, as shown.

Some members of the Acanthus family have beautiful pollen
with peculiar markings. Lbonia floribunda is represented at
Fig. 13, and Sericographis Ghiesbreghtiana at Fig. 14. One of

* The pollen of F. procumbens is figured in ‘ Gardeners’ Chronicle, Sept. 5,
1874, p. 291.

14 Notes on Pollen. By Worthington G. Smith.

the most peculiar and handsome of all pollens is found in Thun-
bergia, another member of the Acanthus family, T. Harrisiz, shown
in Fig. 15. .

Turning now to the Scrophularia family, Mimulus moschatus is
shown in Fig. 16. I have placed this figure exactly under the
Thunbergia pollen, to call attention to the singular error made by
Van Mohl, who, in one of his plates, figures the former pollen for
the latter. I have also thus engraved the figures to show how
errors are perpetuated, for Mohl’s illustration of Mimulus mos-
chatus is reproduced in the ‘ Micrographice Dictionary, and in two
other English works, without acknowledgment, and all wrong.
The pollen of M. moschatus (a garden plant of long cultivation) is
very variable.. The pollen of one variety will be three times the
size of another, or at times as big in size as the Thunbergia ; but,
though the same in size, it is always totally different in strue-
ture to an experienced eye. Still keeping to the Scrophularia
family, Fig. 17 represents pollen of Calceolaria Pavoni, Fig. 18
that of the Foxglove, Digitalis purpurea, and Fig. 19 that of the
Snapdragon, Antirrhinum majus.

Of the Euphorbia family, Mercwrialis annua is illustrated in
Fig. 20, Xylophylla glaucescens in Fig. 21, and Croton pictus in
Fig. 22.

siete of the finest of all pollens are to be found in the Mallow
family. Fig. 23, Plate CLXVIII., belongs to Hibiseus rosa-
sinensis, and Fig. 24 to Abutilon Darwinit. All the pollens as
seen by us in this family present the same characters. The
common Hollyhock, and the two common Mallows, M. sylvestris
and M. rotundifolia, have especially fine pollen.

Many members of the Composite family have spiny pollens ; that
of Dahlia Cervantesti is represented at Fig. 25, Erigeron Cana-
densis at Fig. 26, and Centaurea cyanus at Fig. 27. The latter,
the pollen of Gazania, and of other members of the Composite
family, considerably depart from the type, and, according as the
plants approach or recede from the Dipsacex, the Valerianea, the
Campanulacee, &c., so the pollens vary. Without doubt many
valuable hints may yet be obtained from a careful examination of
the fresh pollen of the Composite ; sometimes the spines are very
large. Mohl has represented the spines so thin as to be almost
invisible in Sonchus palustris ; and in the inaccurate, unacknow-
ledged copies published in the ‘ Micrographic Dictionary’ and in
other English books, the spines are simply omitted altogether, so
giving a very false impression of the real character of the Sonchus

ollen.
‘ The Canterbury Bell, Campanula medium, has echinulate
pollen, as shown in Fig. 28. This pollen is a good general repre-
sentative of the Campanula family.

Monthly Microscopicai Journal, January 1, 1877. PLATE CLXVIII.

POLLEN GRAINS x 400. Fics. 23 ro 37.
VOL, XVII.

Q

Notes on Pollen. By Worthington G. Smith. 17

We know no more beautiful pollen than that belonging to the
major Conyolvulus, Ipomea purpurea, Fig. 29. Convolvulus
(Calystegia) soldanella is shown at Fig. 30, and Convolvulus
arvensis at Fig.31. These three pollens, it will be seen, are very
different from each other, and they ought undoubtedly to carry
weight with those systematic botanists who are in doubt as to the
natural position of the genera in the Convolvulus family. The
Dodders (Cuscuta) are sometimes placed in the Convolvulus family,
and the pollen of Cuscuta trifoliz, Fig. 32, is certainly the same
in character with Fig. 31, Convolvulus arvensis.

The different members of the Arum family furnish beautiful and
most peculiar pollen-grains, of very diverse characters. Fig. 33
represents the pollen of Phyllotenium mirabile, Fig. 34 that of
Anthurium Patiniw; this latter is a most extraordinary pollen,
marked with projecting longitudinal ribs. Fig. 35 represents that
of Spathophyllum heliconixfolium, 36 that of Anthurium Scher-
zerianum, and Fig. 37 that of Richardia albo-maculata.

The pollen-grains of the Lily family are very characteristic.
Fig. 38, Plate CLXIX., belongs to Lilium longiflorum, and is
remarkable for its large size and its bold and beautiful reticulations.
Fig. 39 is that of L. Californicwm, where the reticulations are
very much smaller. Fig. 40 is that of Aloe Abyssinica, Fig. 41
shows that of Narthectwm ossifragum, that of Fig. 42 Conval-
laria mayalis, and Fig. 43 that of the Crown Imperial, Fritillaria
imperialis.

Passing on to the Violet family, the pollen of the Heartsease,
_ Viola tricolor, is engraved at Fig. 44, and that of the Sweet
Violet, V. odorata, at Fig. 45. Though coming under the same
genus, and possessing many characters in common, some species of
Viola are far removed from each other in nature; the pollens, as
will be seen in the engraving, are very different, and any hybridiza-
tion between the two plants last referred to would appear to be
quite hopeless, although a sweet-scented Heartsease is certainly a
plant to be desired. In answer to a letter from us on this subject,
Messrs. Dicksons and Co., of Waterloo Place, Edinburgh, a firm
noted for the production of some of the very best hybrid Violas and
Pansies now in the market, replied to us in the following terms:
“ We have tried to obtain a hybrid between Viola odorata and
V. tricolor, but have never succeeded, and we never heard of any-
one who had been more successful than ourselves.”

Fig. 46 is the pollen of the tuberous Moschatel, Adoxwa mos-
chatellina; Fig. 47 that of the Snowberry, Symphoricarpos par-
viflora ; and Fig. 48 that of the Elder, Sambucus nigra. As for
the first, it is placed in Caprifoliaceze both by Dr. Hooker and Mr.
Bentham, in Araliacez by Prof. Babington, and in Saxifragacee by
Linneus and Jussieu. Unfortunately, very little is to be learned

c 2

18 Notes on Pollen. By Worthington G. Snuith.

from the pollen in this instance, for it agrees with the Caprifoliacez
in its resemblance to Sambucus, Fig. 48 (but differs in the Snow-
berry, Fig. 47, and the Honeysuckle, Fig. 5); and it agrees with
Araliacez in resembling the Ivy, Fig. 73, and with the Saxifrages
in being very much like the typical pollens found in this genus.
Saxifraga umbrosa (which is characteristic) is shown at Fig. 49.

Fig. 50 belongs to the Cedar of Lebanon, Cedrus Lnbany,
Fig. 51 to Hcheveria secunda, Fig. 52 Arundinaria falcata (or, ac-
cording to the ‘Gardeners’ Chronicle, June 24, 1876, p. 826, the
plant in view is more correctly named Thamnocalamus Falconer),
Fig. 53 Passiflora coelestina, Fig. 54 the Nettle, Urteca wrens.

Turning now to the Gourd family, the pollen of the Melon
(Cucumis melo) is illustrated at Fig. 55, and the Cucumber
(C. sativus), Fig. 56. Judging from the plants themselves, and
the great similarity in the form and size of the pollen, it would
appear quite possible to get a hybrid between the Melon and the
Cucumber ; and a well-known instance is on record of a supposed
intermediate fruit produced naturally in Mr. Watson’s nursery at
St. Albans. For an illustration and description of this fruit,
engraved by the writer, see ‘Gardeners’ Chronicle,’ Oct. 4, 1873,
p. 1335. The fruit was genuine, and was neither grafted or
inarched, but whether or not it was a true hybrid, it certamly was
a natural growth from the Cucumber plant. We believe the fruit
illustrated damped off and rotted, and that no seeds were found
inside. Before leaving the Gourds we may say the pollen of the
Vegetable Marrow, Cucurbita ovifera, is totally different in
character from the two last named, being two or three times larger
in diameter, spherical in shape, and densely covered with spines.
The Bryony of our hedges is again different from all three, but as
large in size as the pollen of the Cucumber.

The common Bitter-sweet, Solanwm dulcamara, bears very
small pollen-grains, Fig. 57. The outline here engraved is a
common form in the Solanum family.

The Polemonium family is remarkable for its truly handsome
pollen, that belonging to Phlow decussata is illustrated at Fig. 58 ;
Cobxa scandens, belonging to the same family, has a pollen about
ten times the bulk of Phlox, and with similar elegant hexagonal
reticulations.

Fig. 59 is a typical representative of the Amaryllis family in
Crinum pratense, whilst Fig. 60 belongs to the common Snowdrop,
Galanthus nivalis, and is the only departure from the typical form
known to us in this family. Very little or nothing can be learned
from a study of the pollens found in the genus Narcissus. The
plants placed under this genus have been so often hybridized and
have been so long cultivated, that the pollens (like the plants them-
selves) vary exceedingly. One anther belonging to a Narcissus will

Monthly Microscopical Journal, January 1, 1877. PLATE CLXIX.

POLLEN GRAINS x 400. Fias. 38 10 63.

3 - - a i 4. 2
= ili art ty 1 ee Soe —- —e
ie a ee Ld a

Notes on Pollen. By Worthington G. Smith. 21

commonly produce pollen-grains of the most diverse sizes. Fig. 59
(Crinum) is typical for shape, but many grains in Narcissus are
linear, while others are triangular, and both these occur in the
same anthers with typical grains.

These latter remarks hold good with the species and varieties of
Tris as found in our gardens. Nothing can be made of the pollens
of the mere garden forms, but that something may be learned from
the study of the pollens of true species is shown by Fig. 61, which
represents the pollen of J. zberica, and Fig. 62 the very differently
formed pollen of I. Kempferi. These two forms, in good species
of Iris, are both striking and constant. Gladiolus and Freesia
have pollen similar in shape with Fig. 62. Fig. 63 belongs to
Crocus aureus.

A great deal has been written as to possible hybrids between
our wild Geraniums and our garden varieties, especially with a view
to get a blue strain of colour into the garden plants. As far as we
know, all these attempts have proved abortive ; and from a study of
the pollens in the Geranium family we are inclined to think that
no such hydrids will ever be obtained. Fig. 64, Plate CLXX., is the
pollen-grain belonging to our little wild Geraniwm sanguineum ;
G. pheum is the same in size, whilst G. pratense is much larger.
On the other hand, Fig. 65 represents the pollen of Pelargoniwm
zonale. In Mr. Turner’s fine collection of Geraniums and Pelar-
goniums the pollens are very similar with the latter. In the
genus Erodium the pollen-grains are globular. In Oxalis, Fig. 66,
O. acetosella, and Tropxolum, Fig. 67, 7. majus, the pollen-grains
agree well with the Geranium family, and in this respect they add
additional weight to the conclusions arrived at by Messrs. Hooker
and Bentham, who place these two genera in the Geraniacee.

The pollen-grains of the Umbelliferze are, as a rule, very cha-
racteristic. That of Heraclewm sphondylium is shown at Fig. 68,
Cinanthe crocata at Fig. 69, Siwm angustifolium at Fig. 70.
The curious genus Hydrocotyle has pollen similar with Fig..71 in
H. bonariensis, and with Fig. 72 in H. nitidula. The pollen of
the common Ivy, Hedera helix, is shown at Fig. 73. Dr. Berthold
Seemann proposed removing the genus Hydrocotyle from the
Umbelliferze to the Araliaceze, but the characters of the pollen as
seen In many genera and species of the two families hardly appear
to us to support Dr. Seemann’s views.

Fig. 74 is the pollen of the Bird’s-foot Trefoil, Lotus cornicu-
latus. This may be considered representative of the Leguminose.
Fig. 75 belongs to Cytisus laburnum, whilst Fig. 76 is Hrythrina
eristagallia curious departure from the usual type.

Of the Labiate family, Fig. 77 belongs to Nepeta violacea,
Fig. 78 to Salvia patens, and Fig. 79 to Scutellaria Mocciniana.

22 Notes on Pollen. By Worthington G. Smith.

As far as our observation goes, these are the three salient and
constant forms found in the Labiate.

Fig. 80 is the pollen of Epacris hyacinthiflora, and Fig. 81
a highly ornamental pollen, belonging to Fumaria officinalis.

Turning now to the Primula family, Primula viscosa is illus-
trated in Fig. 82, P. veris in Fig. 83, and P. denticulata in
Fig. 84. The latter is quite an exceptional form; the other two are
characteristic of the family. The pollen of the common Primrose
varies in size extremely, and the same fact holds good with the
Cowslip and Polyanthus; in all three plants the pollen may at
one time and place be eight times the bulk of what it is at a
different place and in a different situation. Notwithstanding these
variations, our Primula vulgaris is so different in its pollen from
P. japonica that we consider the production of a true hybrid
between the two plants to be very improbable. As far as our
knowledge goes, no one has yet secured a true hybrid between
P. vulgaris and P. japonica.

As an example of the pollens commonly found in the Plumba-
ginacee, Fig. 85 is given from Armeria maritima. Fig. 86 is
from the Holly, Ilea aquifolium ; Fig. 87 belongs to the white
Water Lily, Nymphza alba; Fig. 88 is a pollen-grain of Papaver
rheeas, and is a good representation of the Poppy family. Fig. 89
is the pollen of the Lime, Tilia Europea.

The pollens are all beautiful in the Pink family, Caryophyllacez.
Fig. 90 represents the pollen of the Corn Cockle, Agrostemma
githago, and Fig. 91 that of the Sweet William, Dianthus barbatus.
In conclusion, Fig. 92 is engraved as a representative of the
Cactee in Opuntia polyantha, the pollen-grains being flat disks
and not spheres; and Fig. 93 is from the common Teasel, Dip-
sacus sylvestris. The last pollen illustrated, Fig. 94, is from
Polygala vulgaris; two views are given of this pollen—one the
side at A, the other the top at B: this is without doubt one of the
most ¢urious of all pollens. In the red, white, and purple varieties
of Polygala vulgaris the pollen-grains also vary a little in form.
At the exact time of maturity this pollen is perfectly spherical, but
after it has fallen from the anther for about five mimutes, or at
most a quarter of an hour, it suddenly collapses into the shape
here figured, and this shape it permanently retains unless the
pollen be immersed in liquid.

We have thus hastily passed in review the external aspects
presented by some of the pollens of the common plants of our
fields, gardens, and greenhouses. Only a few families and about
a hundred species of plants have been noticed, so that readers need
not be reminded of how much there is still in the background in
reference to the mere external form alone of pollen. Sometimes

PLATE CLXX.

Monthly Microscopical Journal, January 1, 1877.

POLLEN GRAINS x 400. Fics. 64 To 94.

Microscopy at the American Exhibition. By R.H. Ward. 25

pollen will give a valuable clue to a plant’s relationships, whilst at
other times it will give no clue at all, or it points in various
contrary directions. This is because plants have not descended
one from another in a straight line, but possess complicated rela-
tionships with plants belonging to several different natural orders.
—The Gardeners’ Chronicle.

IV.—Meroscopy at the American Exhibition.
By R. H. Warp, M.D.

In briefly reviewing the microscopes exhibited at the American
Centennial Exhibition, just closing at Philadelphia, it will be con-
venient to classify them in three more or less natural groups: the
Continental, English, and American. All these classes are largely
and characteristically represented by the most interesting and in
many cases by the most distinguished examples of their kind,
affording to microscopical students the best opportunity yet fur-
nished in this country to study and compare the various types and
qualities of tools available for their work.

It will be expedient to mention first, however, a few isolated
and unclassifiable exhibits which are still of sufficient interest to
demand a passing notice, such as a very small upright educational
microscope of no well-marked character, from Switzerland ; a small
instrument from Tokio, Japan, which is evidently an early if not a
first attempt, and a not unsuccessful one, though of unpretending
form and crude workmanship, to imitate the instruments in vogue
in this country a score of years ago; and a couple of large, clumsy
instruments from Canada, one of them from Montreal and the
other in the educational exhibit from Toronto, of which it can only
be hoped that they do not fairly represent the science and art of
our Canadian friends, since they are wholly devoid of any evidence
of the spirit of that progress which has so fully and so fortunately
changed the microscope from a piece of furniture to a tool for
scientific work, and are in fact excellent illustrations of what a
microscope ought not to be for educational purposes.

The Continental microscopes are chiefly represented by the ex-
hibit of Nachet, of Paris, whose compact, ingenious, elaborate, and
thoroughly built instruments are present in large numbers and
great variety, constituting, with one exception perhaps, the most
exhaustive exhibit in our department. Besides the familiar Nachet
stands, large and small, monocular and binocular, for one observer
and for more than one, and of course the inverted microscope of
Professor J. L. Smith, which the manufacturer never should have

26 Microscopy at the American Exhibition. By R. H. Ward.

allowed to pass as his own, there are dainty pocket microscopes in
eases of wood or nickel-plated metal, clinical, tank, and dissecting
microscopes, and a few accessories, which, though not absolute
novelties, are at least not usually seen on sale in this country.
The most conspicuous and possibly the most worthless article in
this exhibit is a huge inverted microscope, as big as a small stove-
pipe, in which great amplification is gained by means of the great
distance between the ocular and the objective.

Bardou and Son, of Paris, also exhibit, in connection with a
large display of telescopes and other optical goods, one large in-
strument of the French style, having no important characteristics,
and a few inferior instruments.

Austria is represented by 8. Plossl and Co., of Vienna, whose
little case contains a compact histological microscope of excellent
design and attractive appearance. In place of a rack, a pair of
arms attaches the body to the milled heads near their circumfer-
ence, changing the rotary to a plunging motion, as if the driving
wheel of a steam-engine moved the piston-rod, and giving a very
delicate adjustment just as the body approaches a state of rest.
Accompanying this instrument is a clinical one, of the German
style, and far simpler than the French, English, or American
forms.

The handsomest case of instruments in the English department,
and indeed in the whole exhibition, is that contributed by the Ross
house, of London. Less than this could hardly be true of a finely
finished show-case well filled with their almost unequalled work-
manship. With the exception of the new Wenham adaptation of the
Jackson form of stand, and the series of new Wenham objectives
which are understood to have been entered for competition and then
permanently removed from the exhibition and the country, there is
but little in the exhibit that would be called novel, most of the forms
seen being the familiar and standard styles of several years past.
No better commendation of the new stands, whose beauty is uni-
versally conceded, could be desired than is furnished by the old
style Ross stands exhibited by their side. Notwithstanding the
solid workmanship of the latter, and the care with which they were
doubtless packed for transportation, the transverse bar which joins
the body to the rack has in nearly every case given way under
some unfortunate jar and become hopelessly though not conspi-
cuously deformed. ‘The untimely removal of the set of compara-
tively unfamiliar objectives from the exhibition could not have been
an intentional breach of courtesy or propriety, but was certainly
an unfortunate mistake on the part of both the proprietors who
desired and the officials who permitted it.

R. and J. Beck’s exhibit is perhaps the most complete in the
exhibition, but is so badly displayed as to present a scarcely

Microscopy at the American Hexhibition. By R. H. Ward. 27

attractive appearance. ‘The large number of standard forms and the
numerous and convenient accessories made by this firm have been
so extensively exhibited and sold in-this country that their’ pecu-
liarities are well known. ‘The chief novelties are a much-needed
addition of centring and rotating adjustments to the sub-stage, and
a showy introduction of aluminium mountings in some of the
stands.

Henry Crouch, of London, also exhibits a full series of instru-
ments characterized by a greatly improved quality of moderate-
priced work, a class of work for which there is an increasing
appreciation and a growing demand. His best stands of medium
size lack scarcely any advantage as compared with far more clumsy
and costly first-class stands. His variety of acsessories is large
and well selected, showing an earnest endeavour to adopt the best
novelties from every source. His manufacture of a small histological
instrument, with short body, low stage, and horge-shoe base, after
the Continental method, is one more evidence of the growing
favour with which such instruments are regarded in England and
America, especially as it is sold at a price greatly disproportionate
to its size and elegance.

Of Negretti and Zambra it need only be said that along with
other goods they display a small variety of microscopes, of which
but one, the largest, 1s notable, and that merely for its bigness. It
belongs to the furniture style of instruments, and so does its large
case of accessories. Precisely the same words may be applied,
except as to numbers, to the two huge instruments of J. H. Dall-
meyer, the smaller of which is, in the writer’s judgment, too large
for any known use.

The class of American instruments, though not as distinct a
group as the other two, is mentioned separately for local reasons as
well as on account of some peculiarities which its members have in
common. Certainly first among these is the exhibit of Joseph
Zentmayer, of Philadelphia, who offers the most elaborate and
elegant instruments as well as the largest variety of different
forms. His ingenious contrivances and excellent brasswork are
too familiar to need description. He shows the large American,
intermediate, hospital, and clinical stands, and the new student’s,
introduced a few years ago to meet the demand for histological
instruments ; also a material modification of the American, intro-
duced this summer and known as the model, having the three new
features of a fine adjustment by a long slide close behind the rack
and moved by a screw and lever nearly in the Ross position, an
interchangeable stage which can be almost instantly removed and
replaced by an extremely thin diatom stage, and a bar, which
carries the sub-stage and mirror, hinged at the level of the plane of
the stage so as to enable the illuminating apparatus to revolve with

28 Microscopy at the American Exhilition. By R. H. Ward.

facility and in an easily measured position around the object as a
centre. He also exhibits a new pocket microscope of neat and
apparently serviceable construction.

T. H. McAllister’s case, in the photographic building, exhibits
his two or three grades of instruments, with chain movements, thin
stages, and often iron bases, built with a view to both economy and
excellence ; and also a new-model physician’s microscope, which is
literally a charming little instrument, very portable and handsome,
and combining with most of the excellences of the maker's former
work the Zentmayer glass sliding stage and the diaphragm in the
stage close to the object. The objectives furnished with it vary
from fair to the best, according to the pecuniary views of the pur-
chaser. The accessories are of the usual forms.

Bausch and Lomb, of Rochester, who have lately added to the
province of the Vulcanite Optical Instrument Company, of that
city, a microscopical department, under charge of E. Gundlach,
formerly of Germany and late of Hackensack, N.J., exhibit a
large series of entirely new designs. These are all of excellent
workmanship, though of low or medium grade as to size, com-
plexity, and cost. By simplifying the designs, introducing vul-
canite into the mountings where it can be done to advantage, and
introducing the business principle of attempting to create a large
demand by production at a very low cost, the experiment of offer-
ing good instruments at a very low rate is being tried on a scale
and with facilities unprecedented in this country. The special
peculiarities of these stands, aside from the vulcanite mountings,
are the hinging of the sub-stage bar at the level of the object, con-
testing in this respect the priority with Zentmayer’s new stand ; a
new object carrier, which with some improvements may be conve-
nient ; a new fine adjustment, by means of a screw acting on the
body, which is supported at the end of two parallel horizontal
springs, which allow a peculiarly smooth motion practically in-
capable of deterioration from wear or any other probable cause ;
and a coarse adjustment, consisting of a slide at the upper part of
its course, and, below, a rapid screw which prevents pushing the
body suddenly through the slide, and, without interfering with a
prompt adjustment of low powers by sliding, gives a delicate adjust-
ment for higher powers by screwing. This method is evidently a
modification of Wale’s oblique slot.

George Wale’s new student’s microscope is exhibited by the
Stevens Institute of Technology. ‘This is indeed an educational
microscope, and not a burlesque on the claim of the instrument to
educational value. It is a small and compact stand, of the Con-
tinental style, with horse-shoe base and low stage, of most sub-
stantial workmanship, adopting the Zentmayer glass stage, and
introducing an original coarse adjustment by means of a sliding

Microscopy at the American Exhibition. By R. H. Ward. 29

tube with the addition of a pin moving in an oblique slot and
giving a rapid and very steady and safe adjustment by means of a
screwing movement, and an iris diaphragm capable of being used
after the Continental plan close to the object slide, consisting of a
thin split tube whose blades are overlapped and gradually closed by
being screwed up into a dome-shaped cavity in the bottom of the
stage plate. The instrument is furnished with Wale’s excellent
lenses.

James W. Queen and Co. exhibit their instruments, which are
of the English type, reduced and adapted to the student’s microscope
grade, and aim rather to combine well-known excellences into a
good and popular instrument, than to introduce novelties of con-
struction.

The instruments by W. Y. McAllister, in the Pennsylvania
State Educational Exhibit, do not seem to suggest any of the pro-
gress of recent years.

A set of William Wale’s exquisite lenses was exhibited by
Mr. Zentmayer, but was unfortunately allowed to be prematurely
removed from the case.

Several makers are conspicuous by their absence. All visitors
to this department would have been glad to see Hartnack, and
Powell and Lealand, and the German makers, well represented ;
and many felt disappointed at the absence of Spencer, of Tolles,
and of Grunow, having very reasonably expected that such promi-
nent American makers would, from motives of fitness and courtesy,
if not of interest, contribute their share to the completeness of the
International Exhibition. It would have been peculiarly appro-
priate, in view of their undisputed excellence and their high claims,
that the new duplex-front objectives of Tolles should have been
placed in comparison with the world’s other lenses, while the
unhandsome insinuation which is being extensively printed in
advertisements, that they are not at the exhibition because they
would not be properly examined there, must have been authorized
without serious thought by the persons responsible for it. It is
well known that President F. A. P. Barnard, who was associated
with such judges in this group as Professors Joseph Henry,
J. E. Hilgard, and others scarcely less distinguished, gave his
personal attention to the examination of the exhibits in this de-
partment.

Among the objects, other than microscopes, of special interest
to microscopists, may be classed the double-stained vegetable pre-
parations by Dr. Beatty, the large series of fine mounted objects by
W. H. Walmsley, and the far from equal set of imported objects,
both exhibited by James W. Queen and Co., and the more limited
series of pathological specimens, by Dr. H. N. Krasinski, in the
Russian department; the already famous machine for micro-ruling

30 Microscopy at the American Exhibition. By R. H. Ward.

on glass, by Professor Rogers; the hitherto unequalled photo-
micrographs, by Dr. J. J. Woodward, exhibited by the Army
Medical Museum, and the good though less pretending attempts
in the same direction, by Dr. Carl Seiler, in the photographic
building ; and the large, mteresting, and carefully prepared series
of minute fungi, with tinted drawings of the same, contributed by
Mr. Thomas Taylor to the exhibit of the department of agriculture
in that most creditable portion of the whole exhibition, the United
States Government Building.—American Naturalist, December
1876.

( 3l )

NEW BOOKS, WITH SHORT NOTICES.

The Fungus Disease of India: a Report of Observations. By T. R.
Lewis, M.B., and D. D. Cunningham, M.B., Special Assistants to
the Sanitary Commissioners of the Government of India. Calcutta:
Government Printing Office—As to the important question whether
this disease—which is not uncommon in India—is caused by the
growth of a peculiar fungus, the Chionyphe Carteri, or not, the
present work is intended to decide. It is in point of diction a clear,
readable account of the evidence pro and con on the point, and it
moreover contains an abundance of very admirable illustrations
(some of them coloured), both of the appearance of the limb in its
unmagnified state and of the different forms that are observed when
high powers are employed. And what is the result arrived at by the
two thoroughly competent observers whose labours we have now
before us? It is this, that the so-called fungus-foot of India is not a
disease produced or promoted by the growth or development of any
species of fungus whatever. And what are the arguments in favour
of this view of the matter? They are two or three. In the first
place the nature of the roe-like bodies of pink and black masses has
been made out to a certain extent. At all events, it is shown that
they are not in any shape or form a fungus growth. On the contrary,
the investigations made into the matter have shown that the first of
the peculiar morbid products is simply “ fat in various modified
forms.” The second did not display “the slightest trace of a fungus
or of other vegetable organisms” in its constitution; and the third
consists “ of degenerated tissue mixed to a greater or less extent with
black pigment and fungoid filaments.” Now, fungoid elements have
refused to grow when an attempt to cultivate them has been made.
Therefore the authors think there is no need taking them into con-
sideration. But what do they give us in their stead? On this point
it must be confessed the book is particularly barren. It is true they
cite two or three experiments which we confess do not prove very
much, and then they go on to conclude that “ taking everything into
consideration, it seems probable to us that some local degeneration
takes place in the madura-disease giving rise to a product which is
ih one of its varieties peculiarly adapted to the development of vege-
table organisms.” From which it appears to us that it would have
been better for the authors to have withheld the publication of their
researches till they had more positive evidence and less speculative
fancies to give us on such an important subject as this one un-
doubtedly is.

VOL. XVII. D

( 82 )

PROGRESS OF MICROSCOPICAL SCIENCE.

Observations on Rhizopods.—Some investigations have been recently
conducted on Rhizopods by Professor Leidy, who stated to the
Philadelphia Academy, that last July, in the sphagnum swamps of
Tobyhanna, Pocono Mt., Monroe Co., Pa., he noticed an abundance of
a Rhizopod which he thought he had not previously seen, and which
he at first supposed to be an undescribed species, but which he now
viewed as a variety of Hyalosphenia ligata. From this, as previously
described, it differs in the test being of a pale sienna colour, and per-
haps of greater thickness, but otherwise is like it. The test is com-

ressed pyriform, with the length and breadth nearly or about equal,
and the thickness one-half. The lateral borders are obtusely rounded.
The mouth is transversely oval. The sarcode is colourless, and
attached to the inside of the test by diverging threads. The pseudo-
pods are usually from two to three. Measurements -08 mm. long and
broad, and +036 thick, with the mouth +02 broad and -008 wide.
Others varied from *06 long and -08 broad, to -092 long by °064
broad. In observing the Pocono variety of Hyalosphenia ligata, and
the beautiful and well-marked species Hyalosphenia papilio, he de-
tected an important point of structure which previously had escaped
his notice. In the active condition of these, and other Difflugians,
they are seen with one or more pseudopods extended from the mouth
of the test, to the margin of which the sarcode is attached, as well as
by diverging threads to various points of the interior of the test. The
interval between the body of the sarcode and the interior of the test is
occupied with water. The extent of the interval increases with the
increase in number and extent of protrusion of the pseudopods, and
also varies according to the degree of emptiness or repletion with food
of the sarcode body. When the pseudopods are withdrawn into the
mouth of the test, the mass of the sarcode expands in a corresponding
ratio, and the threads of attachment to the inside of the test contract
in length. The intervening water appears to be displaced through
small apertures of the lateral borders and fundus of the test, which
exist in numbers usually from two to half a dozen or more.

The Early Development of the Mammalian Embryo.—Mr. E. A.
Schifer, of University College, has contributed a valuable paper on
this subject to the ‘ Proceedings of the Royal Society’ (No. 168); and
we much regret that our notice of it has been so long “ crushed out.”
The paper is upon only the early stages of development; but those
who know anything of the subject of development are aware how very
incomplete is our actual knowledge on these points. Mr. Schiifer
noticed these ova in the cornua uteri of a cat which had been just
killed. He observed five swellings in the cornua, and an equal
number of corpora lutei in the ovaries; therefore he concluded that
these swellings were ova. So removing the uterus, and placing it in
a weak solution of bichromate of potash, he proceeded carefully to slit
open the cornua under the fluid with fine scissors. As each one of the

PROGRESS OF MICROSCOPICAL SCIENCE. 30

above-mentioned dilatations was reached, a minute, beautifully clear,
vesicular body floated out into the surrounding liquid; there was no
sign of any adhesion to the uterine wall. He then goes on to say :—

“The vesicles were as nearly as possible similar in size and
appearance, and a description of any one of them will serve for all.
Their shape was oval, the long diameter measuring about + inch,
the short about 51; inch, and the outline being perfectly smooth and
even. Under a low power of the microscope, the vesicle was dis-
tinctly seen to be bounded by a primitive chorion or thinned-out
zona pellucida. No trace of villi or projections of any sort could be
detected on its surface. Besides this envelope, the wall of the vesicle
was composed of what appeared a simple layer of flattened polygonal
cells, closely lining the zona. But under a somewhat higher power a
stratum of more deeply lying cells could, in some parts at least, be
detected by focussing; moreover, a shadow at one place, midway
between the poles of the oval, appeared to point to the possibility of
the existence of a slight thickening at this part, although a well-
defined shaded area was, in no sense of the word, visible.

“T was led to imagine that the ‘ shadow’ in question, or rather the
thickening to which it was probably due, would be caused by the first
beginnings of a mesoblast at this situation. But nothing more could
be made out in the fresh condition, and the little vesicles (at least two
of them, for the others were of less value for the purpose of sections,
owing to the blastoderm having shrunk away at various places from
the zona, and presenting a crumpled, distorted aspect) were accord-
ingly hardened in the usual way in very dilute chromic acid, stained
with logwood and with carmine respectively, imbedded by the gum-
process,* with the object of filling the cavity and thus supporting
the enclosing parts and preserving them in their natural positions ;
and finally sections were made across the long axis of the oval, and
were mounted in glycerine and examined.

“A glance at the sections is sufficient to show that the blasto-
dermic vesicle is in the bilaminar condition. There exist within the
zona pellucida, or primitive chorion, two distinct layers, the section of
each forming a complete circle; the whole structure, therefore, in-
cluded by the zona being formed of two separate vesicles, one within
the other. The outer of these is of course the epiblast, the inner
doubtless representing the hypoblast; we may speak, then, of an
epiblastic and a hypoblastic vesicle. In none of the sections was
there any trace of an intermediate layer of cells or mesoblast. The
epiblast closely lines the zona throughout; but the hypoblastic vesicle
is considerably smaller, so that except at one part, where it comes
into closer proximity than elsewhere with the epiblast, it is separated
from the latter by a considerable interval, filled in the fresh condition
by a clear fluid. This fluid would seem to be of a different nature
from that which occupied the cavity of the hypoblastic vesicle, for the
coagulum produced in it by the action of the hardening liquid has a

* A bad method for embryos; but I was at the time ignorant of Kleinenberg’s
' excellent plan for effecting the same object. See Forster and Balfour, ‘ Elements
of Embryology,’ p. 249.

D2

34 PROGRESS OF MICROSCOPICAL SCIENCE.

much more granular appearance in the sections. Both epiblast and
hypoblast throughout almost the whole extent are composed of a
simple layer of flattened cells joined edge to edge. Most of the
epiblastic cells exhibit in a high degree a condition of the nucleus
which is frequently met with in epithelial cells elsewhere—a ten-
dency, namely, to become separated into a clear colourless part, and
a highly refracting and usually somewhat irregular body, which
readily becomes stained by the usual colouring reagents. This change
is no doubt a post-mortem effect, probably produced by the action of
the reagents employed. The hypoblastic cells do not for the most
part present this appearance; their nucleus remains large, round, and
clear; and the cell-substance does not become stained as much as that
of the epiblastic cells.

“Tt was mentioned above that the epiblastic and hypoblastie
vesicles come into closer proximity at one part of the circumference
than elsewhere; even here, however, they do not come into actual
contact. At this place they are no longer formed, as elsewhere, of a
single layer of cells; but their component elements, besides being
rounder in shape and smaller, are two or three deep, although not
arranged in as many definite strata. Both layers are in consequence
somewhat thickened just here, the thickening (which is mies marked
in the epiblastic vesicle) extending over an area of about 1, inch in
diameter ; not sharply defined, however, but gradually shading off
into the thin part. Both epiblast and hypoblast are, it may be
repeated, perfectly well defined and distinct from one another here as
elsewhere ; and there are no cells to be seen which do not clearly
belong to one or the other. Moreover, they are not only separated
by a small but obvious amount of the granular material (coagulated
fluid) previously mentioned, but there is in addition an exquisitely
fine pellicle, which in the sections appears as a mere line passing over
and forming a definite boundary to the upper (outer) surface of the
hypoblast at the thickened area. This membranous pellicle, for
which I would venture to propose the name of membrana limitans
hypoblastica, is, as made out in teased preparations, perfectly homo-
geneous, and continues so throughout its extent. It becomes stained
slightly by carmine, but apparently not at all by logwood, and is
probably to be looked upon as a cuticular formation produced by the
hypoblastic cells. Whether the delicate pellicle may extend around
the whole hypoblast in the natural condition, I am unable to say; in
the sections, at any rate, it appears to terminate towards the periphery
of the thickened area, and to have become curled somewhat away from
the hypoblast.

“T am not aware that a similar structure has yet been noticed in
the early blastoderm of any animal; but its importance in this case
in bounding the hypoblast is evident. Indeed, if it should be found
that the membrane in question is of general occurrence in the mam-
malian germ, and that the first appearance of the mesoblastic cells
occurs external to it, as from its proximity to the hypoblast there is
little reason to doubt, the fact of the existence of such a film between
the commencing mesoblast and hypoblast is strongly in favour of the

PROGRESS OF MICROSCOPICAL SCIENCE. 35

view which derives the former from cells of the epiblast, as against
that which would assign to it a hypoblastic origin.”

In conclusion, it may be observed that Mr. Schafer finds that
Hensen has also observed this structure.

The different Sexuality of Volvox globator and V. minor.—This im-
portant subject has been investigated by M. L. F. Henneguy, who read a
paper before the French Academy in July last. This paper is abstracted
at some length by the ‘Academy. It states that M. Henneguy de-
scribes Volvox minor as dioicous, while the V. globator is monoicous ;
and its reproduction has been recently described by Cohn.* The
dioicous volvox is a colony of unicellular alg, each member being
furnished with two vibratile cilia, and all disposed regularly in the
gelatinous wall of a hollow sphere. M.Henneguy finds four kinds of
these colonies, which he calls cenobiums: 1, containing only vege-
tative cells, and having young ccenobiums in their interiors, each
derived by division and multiplication of a vegetative cellule; 2, a
great number of these cenobiums which contain, likewise, male
elements, androgonidia, situated in the thickness of the gelatinous
wall; 3, those which exhibit only vegetative cells and androgonidia,
and not producing any daughter colonies ; 4, female ccenobiums which
contain only gynogonidia, or oospheres in the interior of their spheres.
The androgonidia are formed at the expense of a vegetative cell
which acquires a larger volume than the rest, and divides into
parallel segments, each having the form of an elongated cone with
its thickest end green, and the other one transparent with a little red
point, and two vibratile cilia. The bundle of antherozoids exhibits a
continual oscillation in the antheridium. The gynogonidia spring
likewise from a differentiation of a vegetative cellule, which grows
much larger than the androgonidia, and becomes full of starch and
chlorophyll granules, giving the oospheres a dark-green aspect. At
the moment of fecundation the bundles of antherozoids are set at
liberty by the dissolution of the antheridia wall; they move quickly
through the water, and fix themselves on the female ccenobiums, and
then separate to fecundate the oospheres, but the author was not able
to observe the exact moment of their penetration. After fecundation,
the oospheres surround themselves with a thick membrane having a
double outline, which was not previously visible, and rapidly change
colour, passing from dark green to yellow green, and then to orange.
They then contain a red oily matter and a larger quantity of starch.
This orange coloration made some observers suppose it was a separate
species, the V. aureus, Ehr. These volvocina, male, female, and
neuter, seek the light and keep near the surface of the water; but
when the female colonies are fecundated they get away from the
surface. In a glass vessel the green ones will be seen on the side of
the light: the others on the opposite side. If the vessel is turned
round they change places, and the orange ones fly from the light
quicker than the green ones seek it. When these objects first appear
in the waters where they are formed, scarcely any but neuter colonies

* « Beitrage zur Biologie der Pflanzen,’ 1875.

36 PROGRESS OF MICROSCOPICAL SCIENCE.

are seen—that is to say, only those which give rise by segmentation
to daughter colonies. After a little time the number of colonies
contained in each ccenobium diminishes, and then a great number
appear with the androgonidia, which represent aborted daughter
colonies. At this moment we find a few female groups not containing
daughter colonies. After reproduction has gone on for some time by
means of daughter colonies, we observe the number of female coeno-
biums augment, and some composed exclusively of males appear,
while the neuter sorts become very rare. M. Henneguy compares
these facts with what occurs among plant-lice, which degenerate after
the parthenogetic production has gone on for some time, and their
digestive and generative organs tend to atrophy. Males are then
produced, and, subsequently, females requiring fecundation.

The Embryology of Cucumaria doliolum.—This has been described
by Professor Selenka as follows :—After the formation of the single-
layered blastoderm, and the embryo breaks through the egg-skin, it
swims freely by means of its ciliated membrane. As the flagella
gradually disappear, its activity is reduced to a backward and forward
motion, and when the tentacles are protruded it sinks to the ground,
and moves only by crawling. After fecundation the nucleus (Kern)
diminishes, and becomes a mere drop of protoplasm, inside which a
germinal speck (Kernhof) appears in an hour or two. The segmen-
tation of the yelk goes on till 250 cylindrical flagellate cells are
formed. ‘When the embryo emerges from the egg and swims in the
open water it contracts itself in about twelve hours to about one-fifth
of its diameter. Hereupon from its hinder pole, and below a flattening
of the same, three to eight blastoderm cells project inwards. The
endoderm is formed by cells springing from the flattened pole of the
blastoderm, which rapidly multiply by fission. The mother-cells of
the mesoderm remain in their original position, while the daughter-
cells, as amoeboid bodies, or motile cells, move about in the yelk, till
at last the segmentary cavity (Furchingshéhle) appears like a loose
ageregate of stellate cells.” The author describes the formation of
what he terms the primitive intestine (Urdarm) (which begins with
an unfolding of the aboral pole), the commencement of the water-
vascular system, and other matters which could not be explained
without translating his paper in full.

The Structure of the Common Mushroom.—This has been explained
very fully by Mr. Worthington Smith, F.L.S., in a paper which he
read before the Cryptogamic Society of Scotland (September 26),
and which was illustrated by numerous drawings. He says “ that the
entire substance of the common mushroom is made up of excessively
small bladder-like cells ; these cells are so small in size and light of
weight, that no less than 1,500,000,000,000 (one and a half billion) of
cells go to every ounce of the mushroom’s weight. Mushrooms are
generally grown by dealers from spawn or mycelium; this spawn is
nothing but living matted cells in a resting condition, needing warmth,
moisture, and darkness only for vivification. Mushrooms may, how-
ever, be grown from the purple-black dust which falls from their

PROGRESS OF MICROSCOPICAL SCIENCE. 37

lower surface. This black dust again simply consists of nothing but
cells, but in this case the cells are termed spores. These latter are
of a somewhat different nature from-the simple cells of the flesh of
the mushroom, and their outer coat in this species is changed in
colour from transparent to purple-black, possibly from contact with
the air. The cells in the stem of the mushroom are sausage-shaped,
and grow vertically ; on reaching the cap these cells spread over in
an umbrella fashion, and descend into the internal substance of each
individual gill. This internal mass of cells within the gill is termed
the ‘trama’ by botanists. To understand how the mushroom pro-
duces its seeds or spores, a slice should be cut off the side of the cap
of a mushroom from the top downwards. Where the sectional part
is now exposed, the gills which are cut through will look like so
many small fine teeth of acomb. With a sharp lancet a very small
thin transparent fragment must now be sliced off from the top down-
wards, and placed upon a glass for examination under the microscope.
When magnified 250 diameters this fragment will be seen to consist
wholly of simple cells. These ‘trama’ cells are of some importance,
because certain members of the mushroom tribe have no larger cells
of this nature. As these latter cells gradually grow to the exposed
surface on each side of the gill, they get considerably smaller in size,
denser, and less and less transparent. The exposed surface of the gill
is the fruiting, spore-bearing, or hymenial surface. The spores in all
the mushroom tribe are produced in clusters of four on each basidium,
but on the common mushroom and all its varieties, as far as I have
seen, these four spores are generally produced two at a time, and as
the first two drop off the last two appear, so that it is seldom that
more than two are seen in situ at the same time. This phenomenon
teaches a valuable lesson, and one which has, as I conceive, been
quite erroneously interpreted by Professor Sachs,* who says the
common mushroom only produces two spores on each basidium,
and so illustrates the subject in his fig. 174. The cells of the
mushroom increase in number by apical growth. The last-formed
cell repeats the process continuously till the fungus is complete and
the special cells (spores) destined for the reproduction of the species
are reached. The basidium is first a simple cell, seen in two posi-
tions. This simple cell becomes potentially (but often indefinitely)
divided by a longitudinal partition ; each of these divided portions
produces a branch, and each of these branches bears a spore, which in
its turn is again cut off by cell division, this time transversely. The
basidium is now again longitudinally divided ; these portions in their
turn also produce new branches, which give rise to two more spores,
each spore again cut off by a transverse septum. As the two last-
formed spores increase in size they gradually push the two old ones
off their supports, so that unless the whole process is very carefully
watched it might be concluded that the mushroom produces only two
spores (instead of four) on each basidium, as stated by Professor
Sachs.

“'The mature spores on germination of course reproduce the species
* «HWandbook,’ p. 251.

38 PROGRESS OF MICROSCOPICAL SCIENCE.

by means of a series of new cells. All experiments prove the life of
the spore to be very short, but when the spore once germinates and
forms spawn the latter material’ has great tenacity of life, and this
mycelium is commonly, if not always, perennial.”

American Work with the Microscope.—We have been furnished by
Mr. A. 8. Packard with a valuable sketch of the work that has been
done with the microscope in America. This, however, has only to do
with zoological progress; and great though it undoubtedly is, we
cannot agree with the author in his assertion* that it is vastly superior
to the labours during the same time of those who worked at the same
subjects in either France or England. The following is part of Mr.
Packard’s paper, which includes all the American labours in zoology :—
“The epoch of embryology or the developmental study of animals
was inaugurated by Agassiz in 1846. In the publication of his
‘Contributions to the Natural History of the United States, mainly
devoted to the developmental history of the radiates and turtles,
Agassiz was assisted by H. J. Clark, who, under his training, became
the best histologist our country has yet produced. W. J. Burnett,
another histologist, was only inferior to Clark. Macrady, another of
Agassiz’s students, published some papers of importance on the
Acalephs and their mode of development. Desor and Girard wrote
on the embryology of worms. Memoirs of a high order of merit fol-
lowed, from the pen and pencil of Mr. Alexander Agassiz. His
embryology of the Echinoderms appeared between 1864 and 1874;
the memoir on the alternation of generations of the worm, Autolycus,
appeared in 1862; his paper on the early stages of Annelids in
1866; his remarkable memoir on the transformation of Tornaria
into Balanoglossus was published in 18783; and his elaborate
embryology of the Ctenophores in 1874. In 1864, Jeffries Wyman,
at the time of his death our leading American comparative anatomist
and physiologist, published a memoir on the development of the skate.
The beautiful memoir of Hyatt on the embryology of Ammonites was
a difficult research, while the brilliant papers of Morse on the early .
stages of the Brachiopod, Terebratulina, published in 1869-73, enabled
him, by embryological as well as anatomical evidence, to transfer the
Brachiopods from the Mollusca to the vicinity of the Annelidan
worms. His studies on the carpus and tarsus of embryo birds should
also be mentioned. In 1872 Packard published a memoir on the
development of Limulus, and pointed out the affinities of its young to
certain young Trilobites; and he also published papers on the embry-
ology of the Thysanourous, Neuropterous, Coleopterous, and Hymenop-
terous insects. 8. I. Smith traced the metamorphoses of certain crabs
and shrimps. Several entomologists, as Harris, L. Agassiz, Fitch,
Riley, Scudder, Packard, LeBaron, Hagen, Cabot, Walsh, Saunders,
Edwards, and others, have studied the metamorphoses of insects,
while the drawings in illustration of Abbot and Smith’s ‘ Natural
History of the Rarer Insects of Georgia’ were made by Abbot, who
lived several years in Georgia. In 1874 Emerton described the
embryology of the spider, Pholcus, and during the present year an

American Naturalist,’ October.

‘PROGRESS OF MICROSCOPICAL SCIENCE. 39

important memoir by W. K. Brooks on the anomalous mode of
development of Salpa, a Tunicate, has appeared.” We may observe,
in conclusion, that Mr. Packard’s own labours have not been surpassed
by any of those he has mentioned; and though his modesty as the
writer of the paper prevented any notice of himself, we must take
this opportunity of recording the fact of his being one of the first
comparative anatomists in the United States.

The Examination of Muscular Fibres.—The ‘American Naturalist’
(October) publishes a note, in which a mode of double staining these
structures is described. It is as follows:—Dr. Geo. D. Beatty calls
attention to the Lissotriton punctatus (the smooth-skin newt) and the
Amphiuma tridactylum as microscopical treasures, the muscular fibres,
especially of the tongue, being particularly beautiful, the transverse
striz being very well marked, and the nuclei very large in both species,
and greatly elongated in Amphiuma, stretching one-third across the
field with a ith objective and A ocular. The tissues should be
double, stained for the nuclei with carmine and with picric acid
to bring out the transverse striwe. The tissue is hardened by 95
per cent. alcohol, followed by absolute alcohol, and sections cut in a -
section machine or fibres teased out carefully with needles. The
sections or threads are placed for one minute in 25 per cent. alcohol,
soaked for five minutes in Dr. J. J. Woodward’s borax-carmine
solution, soaked about ten minutes in alcohol acidulated with 20
per cent. of hydrochloric acid until the carmine is nearly removed
from all parts except the nuclei, washed in alcohol for a few minutes,
the solution being changed until free from acid; then placed for one-
half to one minute in an alcoholic solution, one-twelfth grain to one
ounce of picric acid, washed in alcohol, and transferred through
absolute alcohol and oil of cloves to balsam for mounting.

The Matrix of Articular Cartilage—Myr. H. A. Reeves writes from
the London Hospital to the ‘ British Medical Journal’ (November 11)
as follows. He says that having “for some months past been engaged
in the study of joints, I have had occasion to apply various methods,
too numerous to mention here; but I wish to bring under the notice
of histologists some means by which the demonstration of the struc-
ture of so-called hyaline cartilage may readily be accomplished. The
perusal of Dr. Thin’s paper on the ‘Structure of Hyaline Cartilage’ *
stimulated the conviction which I have long held and taught as to the
uniformity of structure; and I have endeavoured to convince myself
of the existence of normal fibrillation in human cartilage, if it were
possible. Some weeks ago I placed the fresh articular elbow-ends of
the humerus, ulna, and radius of a woman aged 65, whose arm had
been amputated for the results of senile gangrene, in a 0°5 per cent.
silver solution for ten minutes. They were then removed and exposed
to the light in the dry state (i.e. without being placed in any liquid)
for nearly three days. I had intended to examine them at once, but
other work prevented it. On making horizontal thin sections, and
examining them first as they were and without a cover-glass, and sub-
sequently other similar sections in glycerine, I was struck with the

* ¢Quarterly Microscopical Journal, January 1876.

40 PROGRESS OF MICROSCOPICAL SCIENCE.

appearance of straight bands running in various directions and planes,
separated by bright but somewhat interrupted lines, which in some
parts appeared to be made up of minute round elements, reminding
one of the ‘elastic grains’ described and figured by Ranvier. I
must mention that the cartilages were washed in ordinary water
before immersion in the silver, and that the capitellum was rubbed
with a clean towel, in order to get rid of adhering synovia. My
object in doing this was to avoid any false appearances caused by the
deposition of silver in the synovia and the subsequent shrinking of
the latter. Thinking that this appearance might perhaps be due
either to the age of the woman or to the fact of the limb having been
so long inflamed, or to the change effected during the three days the
cartilages were exposed, I examined the cartilages of younger people
very shortly after removal, fresh and without any reagent, and also
after staining in gold, silver, and aniline dyes; also in salt solution.
I almost invariably recognized the same appearances ; but they are
not so distinct in fresh as in stained preparations. The fibres are
perfectly straight, in this respect and in others differing from those
figured by Dr. Thin of the kitten and sheep. In some of the sections,
rounded, oval, and irregular figures—probably the transverse sections
of similar fibres—were visible; but on this and other interesting
appearances I intend to dilate more fully ere long. It is important
to note that these appearances are not in any way artificial or due to
the methods used, as perhaps may be said of the methods Dr. Thin
employed, and of those of Tillmanns and Baber. The fibrillation is a
continuous right-lined one, differing much from that figured by Till-
manns and Baber. Once recognized on stained sections they are
readily made out in fresh ones. The gold method I employed was
the following. Fresh articular ends of bones were placed for twenty
minutes in a 0°5 per cent. auric chloride solution. They were then
allowed to remain all night in a 0-02 per cent. solution, and in the
morning were removed and exposed to the light in the dry way all
day. In the evening, horizontal sections were made and examined.
I may add that, after taking every possible precaution to avoid fallacy
in silver preparations, I observed figures very similar to those

represented by Tillmanns, which he deems artificial, of which more ©

anon.”

The Sporules of Seaweeds the cause of Colour in Oysters.—Mz. F.
Buckland states, in a late number of ‘Land and Water, that the
green-bearded oysters which are found not far from Southend,
Essex, owe their green colour not to any mineral pigment. This
peculiar green is imparted to them by the sporules of the seaweed
called “crow-silk,” which grows abundantly in the Roach River.
Dr. Letheby’s analysis has pronounced this pigment to be purely
vegetable, without the slightest trace of copper or other mineral.
Mr. Buckland considers that this vegetable pigment imparts a peculiar
taste and agreeable flavour to the meat of these plump little oysters.

The Anatomy of Moths.—In a work which is entitled ‘A Mono-
graph of the Phalenide or Geometrid Moths of the United States,’

PROGRESS OF MICROSCOPICAL SCIENCE. 41

by A. 8S. Packard, jun., and which forms vol. x. of the final reports of
the United States Geological Survey of the Territories, F. V. Hayden
in charge, the author has gone very minutely into the subject of the
structure of this Lepidoptera. The chapters to which the attention
of microscopists is especially directed are entitled Comparative
Anatomy of the Head, Comparative Anatomy of the Thorax, Deve-
lopment of the Thorax of the Imago, Secondary Sexual Characters of
the Imago, and to the essay on Geographical Distribution. The
imagines of about four hundred species and the early stages of some
are described and figured.

The giving of New Specific Names.—We have some faint hope that
the statement which has been published in the December number of
‘Grevillea’ may have the effect of somewhat abating the nuisance
which exists of multiplying specific names. A misconception seems
to be current amongst some botanists that a MS. name in a private
herbarium, or the description of a new species printed in a report
which is circulated privately, or printed only for the use of a public
department, is sufficient to establish priority for that species. In
order to establish any claim for priority, the gentlemen whose
names are subjoined hold that the species must be published, either
by the circulation of specimens in published fasciculi, or by de-
scription in some work accessible to the public. A privately, or
exclusively, printed report which is not sold or published, is no
security for priority of name. They say: “ We hold that unless a
name or description is so published that it is accessible to botanists,
its author cannot claim for it any other right than that of a manu-
script name. It is presumed that if a description is published it is
known, or might be known, to all botanists, but such presumption
cannot be extended to names or descriptions privately printed ; for
acquaintance with which no facilities are offered either by purchase
or otherwise. We are assured that we are only expressing the
general view of this subject which is recognized by all European
naturalists. It would be manifest injustice to expect naturalists to
respect names with which they cannot possibly become acquainted
through the ordinary channels of scientific literature. The first
published name, when accompanied by a sufficient diagnosis for the
identification of a species, has recognized priority. Had not this
plain doctrine been ignored or controverted, we should not have
considered such an explanation necessary.

“M. J. Berxetzy, J. M. Cromete,

“RR. BrarraHwaitr, F. Kirron.”
“M. C. Coors,

Cell-division studied Microscopically.—This important subject has
had a valuable paper devoted to it in a late number of the ‘ Comptes
Rendus, * by M. H. Fol, which is well abstracted, although the
language of the original is technical in style, in a late number of the
‘Academy. He has not studied the subject in the case of the Verte-
brata, but he has examined the nature of the process of cell-division

* No. 13, vol. 1xxxiii.

‘

42 PROGRESS OF MICROSCOPICAL SCIENCE.

as it occurs among sea-urchins, and he states that “ centres of attrac-
tion appear, before each division, at two opposite poles of the yet
absolutely intact nucleus, and seem to consist in a local fusion of the
substance of the nucleus with the vitelline protoplasm, or perhaps an
irruption of the protoplasm in the more fluid interior of the nucleus.
At these two little masses of sarcode soon appear rays of sarcode,
some of which extend into the interior of the nucleus from one centre
of attraction to the other, while others diverge in the vitellus.” The
author then remarks on certain points on which he differs from
M. Biitschli, and states that the medium best adapted to bring out
the true aspect is picric acid followed by glycerine. Osmic acid, he
says, usually causes the disappearance of the extra-nuclear filaments.

Researches on the Echini.—‘ Etudes sur les Hchinoidées, par
S. Loven, from Kongl. Svenska, Vetenskaps-Akad. Handligar. Vol. ii.
No. 7. 4to, with 53 plates. 1875.—The writer of the short notices
in ‘ Silliman’s Journal’ states that this very important work, although
published some time ago, has only just reached him. It is mainly
devoted to a very thorough and complete study of the skeleton and
external organs of the entire group of Echini. A few new forms are
also described and figured.

Structure and Movements of Dionea muscipula—An important
paper was published on this subject in the beginning of the year by
M. C. De Candolle, of Geneva; and in the September number of
‘Silliman’s Journal’ Dr. A. Gray, who may be considered one of the
first authorities on the subject, makes the following remarks :—‘ One
noteworthy suggestion—which has already been made here—is
that the sudden change of electrical current at the closing of the
trap, ascertained by Burdon Sanderson (and much insisted on, on
account of its accordance with what takes place in muscular motion),
may have had its importance much overrated. The electro-capillary
currents, which Becquerel long ago demonstrated in vegetable
tissues generally, would almost necessarily be influenced in some
such way by the displacements of liquid which would accompany
any such abrupt change in the turgescence of the parenchyma.
In some experiments made three years ago by Professor Trowbridge,
of Harvard University (which, unfortunately, were not followed up),
it was found that the strong bending of an internode of stem, with-
out lesion, produced a similar electrical effect. M. Casimir De Can-
dolle fairly deduces from his experiments the conclusion that animal
matter is not necessary to the development and vigour of Dionea.
He goes on to the conclusion that the animal matter of the insects
caught is not directly utilized by the leaves. This does not follow.
Very much evidence would be required to rebut the presumption that
the organic matters absorbed are somehow (and even directly)
utilized by the plant. The independent movement of the border of
the trap with its fringe of bristles is explained by the anatomical
structure, which is, as it were, distinct from that of the main body.
The glands are stated to belong to the epidermis only; but the
excitable bristles are connected by the cellular bulb with the suh-

PROGRESS OF MICROSCOPICAL SCIENCE. 43

jacent parenchyma, so that impressions upon the former may readily

-be transmitted to the latter. The closing of the trap results from
the comparatively permanent elastic tension of the largely fibrous
external part of the leaf. It opens by counter-action of the paren-
chyma of the upper or inner side, through turgescence; the closing
results from the sudden diminution of the turgescence, in some
unexplained way. In other words, the trap is held open, and at the
proper moment is let go.”

Fungi on the Bones of a Whale.—Mr. C. B. Plowright states that
about a year ago a young whale was stranded near Lynn, and in due
course the bones passed into the possession of a manure company,
They have been exposed all the time to the weather, and during the
spring and summer were covered abundantly by an orange Fusarium,
as well as by certain moulds. The skull has been sawn in two, and
from a crack in it sprang, during the autumn, a cluster of Agarics,
very near, if not identical with, A. bullaceus, Fr., the main points of
difference being the czspitose habit, and the margin of the pilei
becoming striate or even corrugated as the plants dried. A few days
ago, in the very centre of the cranium a cluster of Agaricus ostreatus,
Jacq., made its appearance, apparently luxuriantly, upon a thin
stratum of dry cerebral matter that lined the interior of the cavity.*

Specks in the Cape Diamonds.—It seems that Dr. Cohen, of Heidel-
berg, has examined the “specks” which are to be found in many of
the crystals of diamonds from the Cape. He thought at first that
they were particles of another modification of carbon. In a large
diamond, weighing eighty carats, however, he discovered a crystal
of specular iron, the larger faces of which lie parallel to the octa-
hedral face of the diamond. Lustre, colour, and form (rhombo-
hedral) all combine to identify it with specular iron, and the crystal in
its habit closely resembles those occurring at St.Gothard. His paper,
which was communicated to the Versammlung des Oberrheinschen
geologischen Vereins, 1876, and is printed in the ‘Jahrbuch fir
Mineralogie,’ 1876, contains some interesting observations on the con-
nection existing between the flawed character and the colour of Cape
diamonds.

The Microscopic Zoology of the Arctic Expedition—We of course
cannot tell when the report will be published, but we are glad to
learn from a paper by Mr. H. A. Alston in the ‘ Academy,’ Novem-
ber 11, that “every opportunity was embraced for dredging and
trawling, and a fine collection of marine invertebrates is the result.
Many of the minute pelagic forms which it is so difficult to preserve
are the subjects of beautiful drawings by Dr. Moss, and a complete
series of soundings illustrates the character of the sea-bottom from
Baffin’s Bay up to 83° 19’ N. lat. Insect life was more abundant
than could have been expected, and a good number of species were
obtained. Botany has received full attention. Our explorers were
rewarded by the discovery of between twenty and thirty species of
phanerogamic plants between the parallels of 82° and 83°—a much

* ‘Grevillea,’ Dec. 1876,

44 PROGRESS OF MICROSCOPICAL SCIENCE.

greater number than was anticipated—and Mr. Hart’s collections at
lower latitudes are both rich and interesting. The cryptogamic
flora was of course much more varied and abundant.

The Relation between Activity of Nerves and the Size of their
Sheath.—Dr. R. Saundly (‘Medical Record’) reports that Herr Dr.
K. Arnt states that a comparison of the facts derived from anatomical
observations, human and comparative, and the results of clinical and
pathological investigations, shows that the development of the
medullary sheaths stands in direct proportion to the activity of the
nerve-fibre. In the lower animals and in the embryo, many nerve-
fibres are naked, and the development of the medullary sheath takes
place by the formation of small round cells (Kugelchen), which
arrange themselves around the nerve-fibre, and finally melt together
to form a homogeneous sheath, which thickens by additional concen-
trically formed layers. He considers its formation to be due to
functional irritation.

Fungi parasitic on Corals.—Dr. Duncan, F.R.S., has given an
interesting paper on this subject to the Royal Society,* and we should
have endeavoured to obtain it for publication but for the great expense
of reproducing the plates. The following is a summary of the facts
elicited by the author’s researches: Quekett, Rose, Wedl. Kélliker, and
Moseley have noticed and described the borings of vegetable parasites
in molluscan shells, fish-scales, and corals; but no special attention has
been paid to the filaments penetrating the last-mentioned organisms.
Corals from the littoral zone down to 1095 fathoms are frequently the
seat of the parasitic growth of two kinds of Achlyew, whose horizontal
range is from Davis Straits to the tropics and 15° S. lat. Fossil
corals of Silurian age were also affected by closely allied, if not speci-
fically identical, growths. The method of investigation is by making
thin sections of the sclerenchyma, and also by dissolving out the carbo-
nate of lime. The parasites are filamentous, and fill up the canals which
they form; they resemble a mycelium, and penetrate the coral, living
upon the organic basis, and having their length, breadth, and straight-
ness, or branchings, dependent on the peculiar nature of the arrange-
ment of the spicula in the different species of the Madreporaria. The
entry is made from oospores, zoospores, and by the accidental contact
of the parasites whilst perforating alge situated on the wall of the
coral; and the penetration and growth appear to be the combined
results of the formation of a soluble bicarbonate of lime by the action
of carbonic-acid gas evolved from the growing end of the tubular
filament, of the pressure incident to growth, and of the movements of
the cytioplasm and the cell-wall. The vegetative life of the parasites
is accompanied by reproductive efforts within the corallite; for the
aggregation of granules within the viscid transparent cytioplasm can
be detected, and their formation into large conidia and into small
unciliated zoospores also. Following the peculiar physiological habit
of the Saprolegnian group of Achlyw, the reproductive elements ger-
minate and produce either large or very small tubes which, after
penetrating the parent cell-wall, get through the solid investment,

* «Proc. Roy. Soc.’ No. 174.

PROGRESS OF MICROSCOPICAL SCIENCE. 45

and become indistinguishable from the filaments derived from spores
attached to the outside. The diameter of the largest canals containing
filaments in which there is occasionally a doubtful dissepiment, and
which flourish in the organic matter between the lamin of a septum,

is ;45 inch; that of the typical and ordinary tubes is from ;31,, to

agp inch; and the finest tubes are as small as 55}5, inch in diameter.

The canals and included filaments in some instances increase in
calibre at certain spots, and even form globular expansions, but
usually the same diameter is retained ; the enlarged portions relate to
the reproductive process. The cell-wall of the filament is in close
contact with the sclerenchyma of its canal. In a littoral species
(Caryophyllia Smithi) the parasite is identical with Saprolegnia feraz,
Ktz.; but there is a manifest distinction between it and those of the
other forms. The parasite of the littoral coral greatly resembles
those of the shells of Mollusca and of the scales of fish. Although it is
quite possible that all the parasites of the corals described may be
referred to one species, their type being altered by the peculiar con-
ditions surrounding them, still it is thought advisable to regard them
as members of two species. The classificatory position of the parasites
is in the midst of a group of forms which have complicated life-cycles,
such as the Achlyans (proper), the Saprolegnie and Empusine and
Botritide, and the filamentous false-root bearing genera Codium and
Bryopsis—forms which are more or less the expressions of one or-
ganism under different conditions and age.

Phallus fetidus. — Mr. Meehan exhibited to the Phil. Acad. of
Science, at its meeting in October last, specimens of what he supposed
to be a variety of this fungus. It was very rare with him, the last
time it had appeared on his grounds was seven years ago. Its brilliant
scarlet colour and strong fetid odour would have attracted attention
had it been in existence during that time. It was doubtful if any
existed in the vicinity, and it was an interesting question whether the
spores or mycelium had been in the ground all that while, or whether
it had been recently brought as a spore in the atmosphere. But the
main point he wished to draw attention to was the attraction the fetid
plant had for meat flies. They abounded on the plants. The common
toad plant of greenhouses (Stapelia variegata) attracted these in the
same way, and it was said to be a scheme to aid the plant in cross
fertilization, the stench attracting the flies, and inducing them to
deposit eggs, under the impression that it was rotten meat; though
what benefit it was to the fly to be thus fooled had never been made
clear to him. In the case of this fungus, however, it would hardly be
contended that the flies had been deceived for the purposes of fer-
tilization, nor could he understand why “ in-and-in breeding,” if bad
for phenogams, should not be injurious to a fungus as well.

The Structure of Precious OpalAt a recent meeting of the
Academy of Science of Philadelphia, Professor Leidy stated that
Signor A. G. Arevalo, proprietor of one of the opal mines in Queretaro,
Mexico, had recently called upon him, and exhibited a large collec-
tion of cut opals of various kinds, comprising the milk-white opal
with a rich harlequin display of colours, the less valued transparent
glassy variety with rich hues, and the red fire opal of different shades,

46 PROGRESS OF MICROSCOPICAL SCIENCE.

also displaying the play of colours of the spectrum. From among
them he had selected several which he exhibited to the Academy as
illustrating in an unusually distinct manner the structure of the pre-
cious opal. One of the specimens is white opal, emitting on one side
from the free surface a brilliant display of colours. These are
reflected from facets ranging from } to 1 mm. in breadth, and of
irregular polyhedral form. The facets are distinctly separated by
fissures, which, in the polishing of the stone, have become more or less
filled with dirt, and they appear to form the surface of a mosaic pave-
ment laid on a basis of amorphous opal, of which the other side of the
specimen consists. The facets are distinctly striate; the strie being
parallel on the same facet, but changing in direction on the different
ones, though pursuing the same general course over comparatively
large areas, as represented in the same figure. The striz, or tubes as
Sir David Brewster considered them to be, vary in degree of fineness ;
some apparently being double or more the thickness of others. He
had not attempted to measure them accurately, but they appear to be
about the size of the lines in the ordinary micrometer eye-piece of the
microscope. There appeared usually to be about four or five striz in
the space of ;4, of a mm. Another specimen is a dark carnelian-
hued fire-opal, which exhibits in directly looking upon it, just beneath
the surface, a patch of round or oval spots of a deeper hue. The spots
range from 1 to 1 mm. in breadth, and are separated by interspaces
from 1 to 2 of a mm. The spots appear as lenticular disks with
finely striated surfaces; the striz being parallel, and on the different
spots pursuing nearly the same course. Viewed at a certain angle,
they mainly emit a rich golden-green hue. In another opaque white
specimen, emitting rich hues, the striated facets are more or less
isolated by amorphous opal, and vary much in size. The smaller
facets are generally irregularly oval; the larger ones appear to be
made up of an aggregate of the smaller kind. Over comparatively
large areas, the striw of the different facets pursue nearly the same
direction, but in contiguous areas they even pursue quite opposite
directions. On the larger patches, also, as I have attempted to repre-
sent them, the strie are not perfectly continuous, but appear to be
rather interrupted in bands. On another part of the same opal the
brilliant patches would appear to pertain to cylindroid or fusiform
rods of the striated opal imbedded in amorphous opal. The striz in
these rods appear to be arranged in regular parallel layers, so that
either longitudinal or transverse sections give rise to the appearance
of parallel striz. From these specimens precious opals would appear
to be constituted of an aggregation of particles of a striated or finely
tubular structure which may be imbedded in a basis of more amor-
phous opal. When isolated by the latter, the particles may appear
as lenticular disks, round or oval balls, or cylindrical rods with
rounded ends and of variable length. When closely aggregated these
particles become more or less polyhedral. The particles in section
in any direction present a striated appearance, and, according to the
varying fineness of the strie, and their inclination, emit the varied
hues for which the precious opal is so much admired.

PROGRESS OF MICROSCOPICAL SCIENCE. 47

MicroscopicaL Contents oF FoREIGN JOURNALS.

Archives de Physiologie, No. 1, 1876.—Histological Researches on
the Trachee of Hydrophilus piceus, by M. C. 8. Minot, with two plates.
In this paper the author goes into the whole subject of the trachez
and their relations to adjoining tissues. The author, by adopting the
picro-carminate mode of staining, has been able to make out the
distinction between the small cells and large ones of the external
epithelium. THe describes the structure of the traches minutely.—
Note on the Structure of certain Tubercular Granulations of the
Testicle, by M. L. Malassez. This has two good plates.—Note on a
case of Myelitis, by M. Pierret. A plate.

Archiv fiir die gesammte Physiologie, &c., Band 14, Heft 4 and 5.—
The only paper of microscopical interest, and that is only half so,
is one on the Histological Structure of the Small Intestines, by A.
Fortunatow, of the Physiological Institute of the University of St.
Petersburg.

Journal de T Anatomie, par Chas. Robin. No. 1, 1876.—On the
Changes of Colour caused by the Influence of the Nerves, by G. Pouchet.
This paper is said to be illustrated by four plates, but unfortunately
they have not been placed in the present number. This is a most
important memoir, being the one selected by the Academy of Sciences
of Paris for the prize in experimental physiology. It relates many
experiments conducted over the whole range of vertebrated animals,
which prove that the changes of colour are produced by the influence
of the nerves on the so-called chromoblasts. This paper extends
to 90 pages.—The second paper is a short one, but it is of especial
interest to the microscopist. It is by M. M. Duval, and is upon
the mode of colouring sections of the nervous system. The chief
value of the method is that it gives a distinct sort of coloration to
the nerve-cells and axis-cylinders on the one hand, to the vessels on
the other, and, lastly, a distinct tint to the envelopes (the pia-mater)
of the chord. The mode consists in adding to the red colour ob-
tained from carmine the blue colour due to one of the aniline dyes.
From this there results a violet tint which differs in accordance with
the structure of the particular parts,

Zeitschrift fiir Anatomie und Entwickelungsgeschichte. Heraus-
gegeben von W. His and W. Braune. 2nd Band, Ist and 2nd Heft.
Leipsic, 1876.—The more important microscopical papers are :—On
the Lymphaties of Bone, by Professor G. Schwalbe. This paper has
not any illustrations, and we do not see that it adds much to what has
been done already by Langer and Budge.—A more valuable com-
munication is that of one of the editors, Professor W. His. It is on
the Structure of the Embryo of the Dog-fish. The author follows the
development of this creature from the time when the ovum has
begun to undergo its first changes after impregnation, until its develop-
ment is completed. The important point in the paper is its bearing
on the researches of Mr. Balfour on the development of the dogfish.

VOL. XVII. E

48 NOTES AND MEMORANDA.

That is to say, the point in this paper, as in Balfour’s, is that
relating to the caudal lobes, which are caused by a thickening of
mesoblast on each side of the hind end of the embryo at the edge
of the embryonic rim.—A paper which is partly microscopical is
on “the Anastomoses of the Hypoglossus Nerve,” by Herr M. Holl.
—The Lymphatics of the Testicle, by Dr. K. Gerster, of the Patho-
logical Institute of Bern. This is a good paper. It is illustrated
by two plates, one plain, and the other coloured. The plain plate
strikes us as a little too perfect. The staining material used was
carmine and a combination of carmine and aniline blue, which
certainly, to judge from the drawing, has acted very well.

NOTES AND MEMORANDA.

Death of David Forbes, F.R.S.— One of our great naturalists
has been taken away from us. David Forbes has died within the
past month, at the early age of forty-eight years. Most of the labour
of his life had been spent on his favourite topics, those of mineralogy
and physical geology. And on these two subjects he has left pro-
bably far more material behind him than has been already published.
But in the branch of microscopic geology he has done much good
work, and of this not the least was the set of papers, splendidly illus-
trated, which he published in the ‘ Popular Science Review,’ on the sub-
ject, then a new one, of the ‘“‘ Microscope in Geology.” These papers
were subsequently reprinted in two German periodicals, so highly
were they thought of at the time; and they may be said to have led
English geologists to the pursuit of micro-geology. Of his labours
in geological science this, of course, is not the place to speak. But
in conclusion a word may be offered on his personal characteristics.
David Forbes was, like his famous brother Edward, a man who loved
truth above all things. He was a keen critic of the scientific doings
of his fellows, but withal a generous one, and his onslaughts when
made were usually on his elder and rarely on his younger brethren.
He was invariably kind and genial in manner; one who thoroughly de-
tested hypocrisy, and admired the blunt and honest outspoken man, who
freely expressed his opinion regardless of the consequences. As a
host, those who have had the good fortune to possess his friendship
knew him best; and of them it is not too much to say, that they have
indeed lost a friend whom it will be difficult to replace, and who will

most assuredly be lovingly remembered by them all the days they
live.

Death of Von Baer.—We have much regret in announcing the
death of this veteran embryologist, the father, we may say, of the

ee

NOTES AND MEMORANDA. 49

study of development. He had reached the advanced age of eighty-
four (84) years. Karl Ernst Von Baér was, though of German
descent, yet a Russian by birth, having been born toward the close
of the last century in Esthonia. However, he studied medicine in
Germany, and in 1817 he received the appointment of Professor of
Zoology in the University of Kénigsberg, which he held till his return
to St. Petersburg in 1837. His greatest work, which will make him
famous for many centuries, is his history of the development of the
human ovum, and it, which was published at Leipzig in 1827, was of
course the result of labour executed in the celebrated German
University. This book is in Latin (4to), and bears the title ‘De Ovi
Mammalium et Hominis.’ His later essays on development were
published in the German tongue, and among the more important may
be mentioned his ‘ Ueber Entwickelungs-geschichte der Fische (4to),
and his ‘ Ueber die Gefaessverbindung zwischen Mutter und Frucht
in den Siuge-thieren’ (folio).

Van der Weyde’s Oblique Illuminator.— Dr. R. H. Ward has
sent us the following note, contributed by him to the December
number of the ‘ American Naturalist, and as it bears upon a question
as to priority of invention, it will doubtless interest our readers :—“ At
the Indianapolis meeting of the American Association for the Ad-
vancement of Science, in August, 1871, P. H. Van der Weyde, of New
York, described a contrivance, believed to be new, for oblique illumi-
nation of transparent objects. It was designed chiefly to facilitate the
resolution of lined or dotted objects, and consisted of a plane mirror
lying beneath the object-slide and parallel to it, from which mirror
light, condensed upon it from above by means of a bull’s-eye con-
denser, would be reflected back at the same angle through the object
and into the objective. These illuminators were shown in successful
operation at the meeting, working best with moderately high powers,
and were freely distributed among the members present. They were
briefly described in the ‘ American Naturalist’ for September, 1871,
being there estimated as ‘a little expedient of great practical conve-
nience. yer since that time the present writer, among others, has
used them habitually, shown them freely, and not unfrequently given
them away. The mirror may be either of silvered glass or of polished
metal. In some cases the object-slide may lie directly upon it while
it rests upon the stage; but frequently the object-slide is best ele-
vated slightly above it. The mirror is most conveniently made of the
size of a slide (8x1), and furnished with glass strips at the ends to
support the slide at any required height ; but it may be made smaller,
say one inch square or round, and sunken in a brass or wooden stage-
plate, or for stands having a sub-stage of any kind it may be madeé of
suitable size and supported from the sub-stage and adjusted for height
in the same manner as the achromatic condenser. It has the advan-
tage of great ease of manipulation and applicability to any stand, and
the drawback of being liable to be interfered with by the presence on
the slide of such obstructions as paper covers or opaque cells or rings

E 2

50 CORRESPONDENCE.

of varnish. Within a few months past it has been brought forward
by Rev. John Bramhall, of Lynn, England ; its previous use and
publication having either escaped the notice or slipped from the
memory of himself as well as of the distinguished microscopist who
has indorsed it and proposed to name it after him.”

CORRESPONDENCE.

Mr. Inapren’s STANDARD OF MEASUREMENT OF MAGNIFYING
Power.

To the Editor of the ‘ Monthly Microscopical Journal.’

Srr,—I did not think that the description of my exhibit at the
last Scientific Meeting of the Royal Microscopical Society would be
printed, or I would have stated the general principle of my proposed
standard for measuring the magnifying power of microscopes. My
note referred only to the instrument exhibited. The principle is as
follows :—A diaphragm of any convenient size is placed at a dis-
tance of ten times its diameter below the surface of a slip of glass in
the position of the object on the stage. The diameter of the dimi-
nished image of this diaphragm, as seen above the eye-piece, is

measured. Then

diam. of image ~ the magnifying power employed,
referred to a distance, or length of body equal to ten times the unit
of measurement. Thus, if the unit be an inch, the power is referred
to a standard of 10 inches; a larger or smaller unit increases or
diminishes the standard of power rateably, but is easily converted
into a 10-inch standard. The size of the diaphragm is immaterial,
provided that it is placed at ten times its diameter below the focus
of the objective, and a slit or scale can also be used. The measure-
ment of the diminished image is easily effected by means of a second
microscope, having an eye-piece micrometer of known value, placed
in a line with, and looking into the eye-piece of the first microscope,
both being horizontal.

I remain, Sir, yours obediently,

Joun E. Ineprn.

OL}

PROCEEDINGS OF SOCIETIES.

Royat MicroscopicaL Society.

Kine’s CoLttecr, December 6, 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.

The President exhibited a facsimile of the first compound micro-
scope ever constructed, made in 1590 by Zacharias Janssen, which he
had been allowed to copy from the original in the possession of the
Scientific Society of Zeeland, at Middleburgh, in Holland.

A paper by the Rev. W. H. Dallinger, “On Nawicula crassinervis,
Frustulia Saxonica, and Navicula rhomboides,” was read by the Secre-
tary, and a series of very beautifully executed drawings in illustration
was exhibited. The paper appears at p. 1.

The President, in proposing a vote of thanks to Mr. Dallinger for
his communication, considered it very interesting in more ways than
one, and that the manner in which the investigations had been carried
out was most excellent. The remark made towards the end of the
paper was worth remembering—that to say a lens would resolve a
certain kind of diatom was a statement of little value, seeing that the
varieties of the same kind were so very different in size and re-
solvability. He judged, however, from the paper that there was no
difference between the fineness of the markings of frustules of the
same species, provided that they were of the same size; so that if the
size of the specimen resolved by any lens were stated, a much more
definite opinion could be formed of its quality. With regard to some
of the statements made by Dr. Woodward, he would mention that he
wrote to him some time ago, and suggested whether there might not
be some difference observed in the number of the markings when
light of different kinds was used. Dr. Woodward had told him he
had tried some experiments in the matter, and believed there were
some such differences, but it would take much time to follow the
matter up thoroughly. He hoped that at some future time they
should hear further upon the subject. He thought, if they might
judge from the tone of what had taken place lately, there seemed to
be just now a great tendency to reverse the process adopted by
naturalists some time ago, of adding as much as possible to the
number of species into which a genus could be divided, by now
uniting all the extreme varieties.

A vote of thanks to the Rev. W. H. Dallinger was unanimously
carried.

Mr. H. J. Slack thought these drawings of Dr. Dallinger’s were
very interesting in an optical point of view. Microscopists were
often told by others that they spent their time in counting dots and
scratches; but unless, as in this case, they did give some careful atten-
tion to these dots, they would be likely to miss facts of the greatest

52 PROCEEDINGS OF SOCIETIES.

use. He knew there were some, and amongst them was Professor
Abbe, who went so far as to say that the results obtained by the use of
high powers on diatoms were entirely fallacious, and he had prepared
a number of diffraction slides to prove it. He had himself seen these
experiments at his own house, and he hoped that there would be an
opportunity for them to be shown to the Fellows of the Society. But
although it might be possible to produce very remarkable appear-
ances by means of a number of gratings ruled in particular ways,
this would not prove that they could not also get effects of similar
aspect due to real structure. Whether these appearances could be
relied on or not, was a question which a series of diatoms such as
those before them gave very great help in solving, for they saw there
a large number of specimens of the same species differing only in
what might previously have been expected from their difference in
size, and when they got this effect they might be tolerably snre that
there was some sort of reality about it. He received some time ago
a slide from Mr. Baker on which he could show in the same field of
view a valve of Rhomboides with the rows of beads running as Mr.
Dallinger showed them, and another which showed them running in
a serpentine form. It was quite certain in this case the latter were
spurious, but there was no reasonable doubt that the others were
real. He did not know whether a drawing of Dr. Pigott’s had been
shown there which had some bearing on the subject. Dr. Pigott was
making some observations upon these spurious images by directing
his telescope upon the bulb of a small mercurial thermometer, and he
found that when the sun shone upon it he could see nothing but
diffraction rings, but when a cloud came over the sun he could see
a perfect reflexion of his own house. He had himself noticed a
similar effect when trying to see with his telescope the two little com-
panions of the Pole star; when diffraction rings were seen plainly,
these small stars were invisible; but on a fortunate evening, when
there was much light in the sky, they were seen quite distinctly.

Dr. G. C. Wallich said he had observed that the size of the
diatoms depended upon the size of the first frustule which grew from
the sporangium in any given pool. He had repeatedly found this to
be the case in India, where they grow very rapidly; the result being
that all which came from the same pool were the same size. They
would find in the collection in the Society’s cabinet * some gigantic
specimens of LN. crassinervis in which the markings were very coarse.
He was excessively glad to hear what Professor Abbe has said on the
subject, because it was exactly his own opinion, for the expression of
which he had got rather severely handled some years ago.

Mr. Ingpen suggested that, after all, the question of genus and
species depended upon difference in shape, and not upon the absolute
number or fineness of the lines. He had not paid much attention to
the subject, and therefore did not speak with authority ; but in the
specimen of NV. crassinexvis there were decided nodules at the end of
the median line which the other closely allied forms did not possess.
He could hardly say that the specimens drawn by Dr. Dallinger were

* Presented to the Society by Dr. Wallich.

PROCEEDINGS OF SOCIETIES. aay

all alike in these particulars; the larger specimen had not got the
rhomboidal curve at all, and the drawings showed a distinct difference
in this respect. One had a larger nodule at one end than at the
other ; another had a nodule at each end; the small ones had no
nodules, but were of angular form; whilst another differed altogether
in having a beautifully curved outline. He mentioned these differ-
ences as bearing upon the question whether the species should not be
determined by the shape and nodules rather than by the number of
the striz.

Dr. Wallich, in reply to a question from Mr. Slack, said he quite
agreed with Mr. Ingpen that the larger specimen was distinctly
different from the others, and that it had not the rhomboidal outline.
He might also mention that in preparing these diatoms, if they were
boiled too long in acid, all the material would be boiled away except
the median column, and with a less degree of boiling they would
constantly find the lateral parts would break away in the acid.

The President said it appeared to him that it was a point well
worthy of investigation whether or not there was a series of con-
necting links between the specimens.

Mr. Slack asked if Mr. Ingpen would examine the specimens from
Cherryfield in his own collection, and see if they dittered in these
respects.

Mr. Ingpen said he would do so; the point of importance was
whether the small specimens and the large ones were the same
species. If he should be called upon to name the large one, he should
hardly call it a Rhomboides at all.

Mr. Slack suggested that if diatomists would allow Triceratium to
go up to seven angles, they need not take much notice of such slight
variations.

The President said that the question before them was not the mere
determination of species, but very important physical facts were con-
nected with and lay at the bottom of it; which had a most important
bearing on a very great number of investigations in many different
branches of science.

Donations to the Library since November 1, 1876:

From
IN GEUTOS VOC KL, fet erou diay Sai bis wee py l2etbd way nosed ‘pce pl ane ne Parton:
AUTEN co UM WIECH Yet ose ticity Medes! icy sat os che se Se Ditto.
NOCH POLEATIS S OURTIAn ese ce elec lit cs | oc) buco” yeeie ee Hicietun Nate SOCICLY/®
Verhandlungen.
Proceedings of the Literary and Philosophical Society of Liverpool.

No. 30. 1876 .. Rene Ditto.
Bulletin de la Société Royale de Botanique de © Belgique. No. 2.

NS Gr eres Ditto.
American Journal of Microscopy. i Now 1 Editor.
Transactions of the Royal Irish Academy (Science). ’ Five parts .. Academy.
Proceedings of ditto. Three parts .. Ditto.
Six sets of ats aaiens with i Pamphlet 6 &e. By Dr. J. J. Wood-

ward .. ap) vase os, isa) game Allanons

William Garrow saee Esq., was elected a Fellow.

Water W. REEVEs,
Assist.-Secretary.

I i ce as ae

= ~usm = SS

— —

54 PROCEEDINGS OF SOCIETIES.

Liverpoont MicroscopicaAL Society.

The eighth ordinary meeting of this Society was held on Friday
evening, November 3, at the Royal Institution, the President, Rev.
H. H. Higgins, in the chair.

Mr. Edward Davies, F.C.S., made a communication on the
Didymohelix ferruginea, formerly called the Gallionella, a genus of
Oscillatoriacee (confervoid alge) which is by no means common.
Through the aid of an old pupil he had found it in remarkable
quantity in drains and ditches in the neighbourhood of the Lochar
Moss, Dumfriesshire, where it accumulates ten or twelve inches in
depth. This deposit is locally called iron ore, and the careful
analysis he had made showed that it contained 33°10 per cent. of
iron, The Didymohelix is a test-object, for the general excellence
of a high-power object-glass, also of the observer’s management of
the microscope.

Mr. G. F. Chantrell, Honorary Secretary, read a paper, “ Recent
Observations on the Development of Animal Life in Vegetable Pro-
toplasm.” He stated, after referring to a recent paper in ‘ Popular
Science Review, that he had devoted some time to the careful study
of the Volvow globator, and had examined a large number during the
recent summer; that there were two kinds,—the early stage, when
they are vigorous and produce young volvoces, and a later one, in
which remarkable changes of the contained spheres are seen, a
gradual development into eggs, and finally the Rotifer; specimens of
these he had shown to members of the Society, and said that there
was no resisting the conviction that the Rotifers (animal) are de-
veloped in the Volvox (vegetable ?), or, in other words, that animal
germs are taken up in vegetable protoplasm, just, as has been said,
that Diatomacez are absorbed into the roots of plants, and are built
up unaltered into their stem substance. These germs develop in the
Volvox into eggs, and then hatch there. Mr. Chantrell said that there
was no more remarkable instance of the power of vegetable pro-
toplasm than is shown in the Oscillatoria which he had recently
under observation. The name is derived from their singular oscil-
lating movements. He had placed some in a live-box and kept them
under observation two or three days ; at first they were extremely active
and life-like, reminding him much of the Spirilla. After two days
these broke up into cells; after a time these loose cells began to
form in small clusters, which still retained a slight restless move-
ment; numbers clustered in a circular form, and these after a while
were invested with a nimbus or ring forming a complete cell. On
further investigation these cells showed movement of the contents,
and contained many nuclei. These facts have been frequently
verified. Mr. Chantrell then referred to the flow of protoplasm in
the hairs or rootlets of the Hydrocharis, or frogbit, a well-known
and common pond plant; and described three conditions of the
circulation, showing, when it became languid and almost ceased,
that living organisms are soon to be seen sporting about in the
internode; that in the hairs of the Nitella he had seen, a few nights

oe

PROCEEDINGS OF SOCIETIES. 55

ago, the same thing; that he had in one live-box the Nitella in
vigorous circulation, an internode in which the circulation had ceased,
and that this was crowded with living organisms, the majority of
which were germs, eggs of animals, and animals themselves.

In another internode he saw an egg enclosed in a large hyaline
cell, showing muscular contraction and the play of cilia, and which
subsequently proved to be a Rotifer. The dead internodes of the
NitelJa vary in their contents, as shown in the accompanying illus-
trations of the typical varieties, many of which are to be found in
Dr. Bastian’s ‘ Beginnings of Life, in his remarks on the Nitella ;
it will, however, take an immense amount of time and trouble to
collate all the living forms that are to be found therein. In the
experiment of treating wheat rootlets with carmine, to show the
protoplasm, the plant has no difficulty in drawing up the minute
fragments of colouring matter, by which the protoplasm is made
evident. The spores or germs of animals are taken up in a similar
manner, and are nourished and develop into life in the flowing pro-
toplasm of the plant; and after circulation ceases, a gradual change
goes on, until you have at last a whole menagerie of animal life,
from the Rotifer downwards.

Mr. Chantrell said, in the light of his long familiarity with these
low forms of life, that for years he had abandoned his belief in the
line of demarcation between the animal and vegetable kingdoms, the
relations are so intimate; and that many of our leading scientists
are now coming to the same conclusion. The paper was illustrated
by a number of drawings from life; and at the conversazione that
followed Mr. Chantrell exhibited. a Rotifer alive in an internode of
the Nitella which was hatched there, and which was making frantic
efforts to escape. It had been found the night before. An interesting
discussion followed, in which the President (Rey. H. H. Higgins),
Dr. Drysdale, Dr. Symes, and others took part.

Dunsink (N.Y.) Microscopican Socrety.

Special Meeting, October 31, 1876.—George E. Blackham, M.D.,
President, in the chair.

Circumstances having rendered it inconvenient for the Society to
meet in their rooms at the City Hall, Geo. P. Isham, Esq., invited
the Society to meet at his residence. The invitation was accepted,
with thanks.

The attendance of members and visitors was unusually large, and
there were present by special invitation the following gentlemen,
members of the Buffalo Microscopical Club, viz.: L. M. Kenyon,
M.D.; Henry Baethig, M.D.; Henry Mills, Esq.; Geo. E. Fell, Esq.

The President, after a few words of welcome to those present,
introduced Professor J. Edwards Smith, of Ashtabula, Ohio, who pro-
ceeded to read a long and highly interesting paper on “The Use
and Abuse of the Microscope as an Instrument of Precision.”

The paper was too long and exhaustive for justice to be done it in
asummary. It is sufficient to say that Professor Smith took a position

56 PROCEEDINGS OF SOCIETIES.

radically opposed to many of the received ideas, and in favour of
lenses of the widest angle of aperture for all kinds of work; even
going so far as to express his opinion that most of the work in histo-
logy and pathology done with the so-called “working lenses” of
narrow angle, would require further attention, and with wide-angled
objectives which recent advances of the optician have put at our
command.

After the reading of the paper, the meeting was resolved into a
conversazione for the examination of the various instruments, objec-
tives, and specimens which had been brought by the members of the
Society and their guests.

Mr. Mills, of Buffalo, exhibited a beautiful specimen of Crouch’s
large binocular stand, and various lenses, among them an immersion
No. 10 (,;th) by Hartnack. The exhibition of the circulation in
Chara, by Mr. Mills, under the binocular with a power of 75 dia-
meters, attracted much attention. Dr. Kenyon exhibited a Powell
and Lealand ;!,th of recent construction, with dry and immersion
fronts. Mr. Fell exhibited a late immersion 4th by Gundlach.
Professor Smith exhibited a Zentmayer army hospital stand with
extra thin stage of his own design, Tolles’ ~5th and }th duplex

objectives of 180° (+) air angle, Tolles’ 4 and { inch solid eye- —

pieces, amplifier, &c.; also a microscope lamp of new construction.
The flame of this lamp is only about 24 inches above the table.
Kerosene oil is burned: there is no chimney, the draught being
supplied by a small fan driven by clockwork: the lamp burns with
a perfectly steady flame of great intensity.

The President exhibited a Queen’s student’s stand with three eye-
pieces, Tolles’ l-inch objective of 30° aperture, and Tolles’ jth
duplex immersion objective of 95° balsam angle.

The following severe tests were exhibited by Professor Smith to
convince the doubting ones (of whom several were present) of the
correctness of the positions assumed in his paper.

1. Navicula (Pleurosigma) angulatum, resolved into hexagons,
direct light, central illumination being secured by a diaphragm plate
perforated with an aperture 5}, of an inch in diameter, and accu-
rately centered.

2. The transverse strie of Amphipleura pellucida (Navicula acus)
—the No. 20 of Moller’s balsamed plate, illuminated by Wenham’s
“reflex” (in this case direct) illuminator: amplification 2000 dia-
meters.

3. Nos. 18 and 19 of same probe-plate, with same amplification
and illumination.

4, Resolution of the 19th band of Nobert’s 19 band test-plate
(lines 112,600 to the English inch) with ordinary oblique illumina-
tion 75° from axis.

(All of the above with Tolles’ duplex (four-system) wet 5th
of 1875.)

5. Resolution of the 19th band of Nobert’s 19 band test-plate
with Tolles’ 1th immersion (duplex) objective of 1876, B eye-
piece : amplification 540 diameters, illumination as in No. 4.

PROCEEDINGS OF SOCIETIES. 57

6. Resolution of third band of the same Nobert plate, 22,500
lines to the inch, with Tolles’ 1-inch objective of 30° aperture,
41-inch solid eye-piece, amplifier and draw-tube: amplification 740
diameters.

In view of the unusual nature of some of these tests, and the
acknowledged difficulty of showing them by lamplight and in a
crowded room, a statement that each and all had been shown, and
that the resolution in each case was palpably strong and decisive,
was drawn up, and has been signed by all the members of the
Society, and their guests who were present.

Mr. Mills presented the Society witha beautiful slide of
Stephanodiscus Niagara and a quantity of living Chara.

After a vote of thanks to Professor Smith for his paper and demon-
strations, and to Mr. Isham for his hospitality, the Society adjourned.

San Francisco Microscopican Socrery.

The regular meeting of the Microscopical Society was held on
Thursday evening, October 5, Vice-President Hyde in the chair.

Mr. C. Mason Kinne donated a slide mounted by him with spicules
of sponge in situ, which was found, on examination, to be well adapted
to show the manner in which the acicular spicules were thrust through
the leathery portion of the animal.

Dr. Harkness sent a slide and some leaves, as set forth in the
following paper.

Dr. Harkness’ Paper.

Dear Sir,—I send to-day to your address, for the Society’s cabinet,
a few leaves of the Xanthium strumarium, a plant well known to the
stockmen under the name of “cockle burr.”

You will observe upon the under surface of the leaves many dark-
brown spots, in some instances no larger than a pin’s head, in others
exceeding in diameter one-fourth of an inch. They may be found at
the present time in the greatest profusion throughout the valley of
the Sacramento. In many localities scarcely a leaf may be gathered
which is free from them. These spots are formed by the aggregated
spores of puccinia (a coniomycetous fungus), growing parasitically
upon the plant.

The accompanying mounted slide contains a section of leaf
showing the brand spores, each septate, with a dark-brown inyest-
ment, and attached hy a short stalk. Mingled with these are a few
sub-globose bodies with yellowish contents; these are uredo spores,
indicative of one stage of development of the fungus.

C. Mason Kinng, Esoa.,
Secretary San Francisco Microscopical Society.

The regular meeting of the San Francisco Microscopical Society
was held on Thursday evening, October 19. President Ashburner
was in the chair, having returned from quite an extended tour among
the microscopists over the mountains, and during the evening gave an
interesting and full report of what he had seen and learned.

58 PROCEEDINGS OF SOCIETIES.

Mr. J. P. Moore presented the Society with two volumes of
‘Spencer’s Biology,’ and Professor Ashburner stated that he had
purchased for the Society, while Hast, one of Tolles’ jth immer-
sion objectives, one each of Tolles’ solid one-half and one-quarter
inch eye-pieces and a Wenham reflex illuminator, the latter of which
was tested during the evening for oblique illumination while resolving
some test diatoms, and it was satisfactorily proven that one of the
greatest advantages of the accessory was its use with the ordinary
thick stages, which preclude the obliquity of light necessary for tests
with high powers. While speaking of this, President Ashburner
stated that in his interview with Professor J. Edwards Smith, of
Ashtabula, Ohio, he noted the fact that his stage was of extraordinary
thinness, and was one of the apparent essentials when nothing but
illumination from the mirror was used. The Society’s duplex +,th
of Tolles’ was used, and the Society’s balsam Méller proof-plate,
and Professor Smith showed Nos. 18, 19, and 20, clear and distinct
within fifteen minutes, although he admitted that the Society’s glass
was not equal to his.

President Ashburner has proved an apt scholar in the manipu-
lation of the objective, and from a subsequent interview with Mr.
Tolles, and with the tenth overhauled and refitted, he is equal to the
emergency, being able to show members of the Society the lines on
18, 19, and 20, as plainly as the pickets on a fence. The new Tolles’
sixth also resolves in his hands the same tests without difficulty, on a
balsam plate which is just what it represents to be.

Mr. J. P. Moore made a further statement regarding the grape-
vine fungus which he had examined and reported on at a previous
meeting, to the effect that the same Erysiphe he had found since on
the native vines.

Mr. G. W. Barnes, of San Diego, sent a communication to the
Society, accompanied with a bottle of sediment obtained from the
water supplied to that city from the bed of the San Diego river, and
desired a statement as to its characteristics microscopically. It was
handed to Mr. Hanks, who promised a report at the next meeting.

Dr. Wythe exhibited a photograph of Zentmayer’s new model, and
during the evening Mr. Banks filled one of the revolving tables with
instruments just from the Centennial Exposition. Among them was
Crouch’s standard microscope, with new centering arrangement, which
was most perfect ; one of Walmsley’s binocular stands, and a Holmes’
class stand.

The regular meeting was held on Thee November 2, with
Vice-President H. C. Hyde in the chair.

Mr. H. G. Hanks donated a quantity of material for mounting in
the way of Cinnabar crystals, showing double termination, from
Sulphur Bank, Lake County, California. He also exhibited a speci-
men of beautifully crystallized Polybasite, from Austin, Nevada, which
silver mineral is rarely found so interesting.

Referring to the sample of water handed to him at last meeting,
Mr. Hanks presented a paper embodying the facts ascertained in his

PROCEEDINGS OF SOCIETIES. 59

examination, as follows {and as most of the remarks are on the subject
of chemistry, these are omitted from the ‘M. M. J.’—Ep.}:

A careful microscopic examination revealed only the lower animal
forms usually present in fresh water.

There is an absence of diatoms and other vegetable forms, which
is peculiar.

The water was filtered off and examined chemically. The only
noticeable feature was the presence of an unusually large quantity of
ammonia.

Mr. Attwood presented to the Society four slides, with the state-
ment that the alluvial gold marked ‘No. 1,” from Sea margin, Otago,
New Zealand, very closely resembles that which he had examined
from this coast, the gold presénting the same scaly and laminated
character, with a beautiful, clean and bright surface, rendering it so
easily acted upon by mercury, and apparently so well fitted for
amalgamation. No. 2. Section of Smaragdite rock from Gilroy:
an exceedingly beautiful section, the smaragdite forming a compact
matrix, in which crystals of garnet are porphyritically enclosed.
No. 3. Section of Smaragdite rock from Bavaria. No. 4. A section
of trachytic greenstone from the C. & C. Shaft, Virginia City. It
is the same character of rock as that met with in No. 4 Shaft, Sutro
Tunnel, the smaragdite having small particles of magnetite im-
bedded in it.

Mr. Attwood also exhibited nineteen specimens of alluvial gold
from New. Zealand, which had been presented to him by Dr.
Hector, Director of the Geological Survey of New Zealand. Small
portions of each specimen were mounted on slides for microscopic
examination, and were from the following localities :—No. 40. Torrent
washed, Otago. No. 14. Lake margin, Otago. No. 16. Sea margin
with iron sand, Otago. No. 3. Tertiary sea beach, Nelson. No. 39.
Tertiary lake beaches, Otago. No. 17. Tertiary river terraces, Otago.
No. 83. Re-wash of river terraces by sea, Otago. No. 29. Re-wash of
lake beach by sea, Otago. No. 23. Re-wash of lake or stream gold,
Otago. No. 34. Older gold drift of Otago: Eocene. No. 8. Older
gold drift of Westland, Pliocene, 130 feet below the sea. No. 6.
Ditto, 1700 feet above the sea. No. 15. Torrent-bed in mesozoic rocks.
No. 2. From old conglomerate (cretaceous age) coal-measures, West-
land. No. 21. Creek placers. No. 2. Silurian. No. 4. Devonian.
No. 3. Hydraulic sluicing of gravels in base of mountains. A. Native
crystals of gold alluvial from mica schist.

Dr. Harkness sent the Society some leaves with a fungus found on
them, and also a slide, mounted by him, with spores of the same,
which was accompanied by the following paper :

T have to-day sent you, for the Society’s cabinet, a slide—No. 283
—together with some willow leaves infested with a fungus. These
diseased leaves are found at the present time in the greatest pro-
fusion upon the willows skirting the Sacramento River. You will
observe that the fungus appears both upon the upper and under
surfaces of the leaves, in bright yellow heaps (sori), which are

60 PROCEEDINGS OF SOCIETIES.

formed by the aggregation of the spores. This fungus is the Melam-
psora Salicini (Lev.) belonging to the order Cemacei. The sori are
scattered, of a bright orange colour in the autumn, becoming dark
or nearly black in the winter. The mounted slide exhibits a section
of a leaf with the spores in situ. These, it will be seen, are crowded
into a dense, compact mass, of a bright orange colour. The spores
are in many instances globose, in others oblong, and are filled with
granules. The sample I send you is but one of very many varieties
of leaf-fungi to be found at the present time throughout the valleys
of California.

Apropos of funguses and the many forms assumed by them in
their development, which are noticeable to even the most casual
observer, that of the Phalloidee is, perhaps, the most marked, though
rare. Mr. Kinne exhibited one found by Dr. Wythe in Oakland,
growing in the open lawn, though their usual habitat are woods and
hedges. This fungus, which is highly poisonous, was identified as
Phallus impudicus. ‘

The regular meeting was held on November 16, and, in the
absence of the President, Mr. Chas. W. Banks was called to the
chair.

To the cabinet Mr. Ewing donated a quantity of washed Richmond
diatomaceous earth, and also a large lot of the raw Maryland dia-
tomaceous earth for mounting.

There being no written communications, the evening was devoted
to the examination of Mr. Banks’ donation and various objects.

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PL.CLXXI.

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MONTHLY MICROSCOPICAL JOURNAL.

FEBRUARY 1, 1877.

I.—On the Relation between the Development, Reproduction,
and Markings of the Diatomacee. By G. C. Watutcx, M.D.,
Surgeon-Major, Retired List, H.M. Indian Army.

(Read before the Royau Microscopical Society, January 3, 1877.)
Puates CLXXI. anp CLXXII.

Ar the close of a paper ‘‘ On the Structure and Development of the
Diatom Valve,” laid before the Royal Microscopical Society in
December 1859, I drew the following conclusions from certain
facts referred to in that and a prior paper “On Triceratiwm,” in
which the same points had been incidentally discussed by me:
“That the growth of the diatom valve ceases entirely, either at
the period of its liberation from the connecting zone of the parent
valve, or immediately afterwards.”

EXPLANATION OF PLATES CLXXI. AND CLXXII.

Puate CLXXI.

(N.B.—The figures in these Plates are, to a certain extent, diagrammatic;
all such markings and details as are calculated to obscure the parts specially
under notice having been omitted.—G. C. W.)

Fic. 1.—Two frustules of Biddulphia pulchella, in which division has just been
completed : p.v.a and p.v.b, the primary valves of the parent frustule ; s.v., s.v., the
two secondary or newly formed valves; P.c.z.a and P.c.z.b, the connecting
zones of the parent valves; d, the double or overlapping portion of the connecting
zones; x, 7, the marginal row of puncta of the connecting zones.

Fic. 2.—A frustule of same, with the connecting zone of the primary valve of
the parent frustule still adherent.

Fre. 3.—A primary or parent valve, within the connecting zone of which the
new valve is being developed by gemmation.

Fic. 4.—A similar valve and its connecting zone separated from each other:
g, the deep groove or channel encircling the free margin of the valve, into which
the inverted edge of the connecting zone dips.

Fic. 5.—A valve of same, showing the buttress-like thickenings which give
the valve of this and some allied species of Biddulphia the appearance of being
divided into Jocu/i.

Fic. 6.—A frustule of Zsthmia nervosa, in which division is about three parts
completed: p.v.a and s.v., primary or parent, and secondary valves.

Fic. 7.—A frustule of the same in which division is completed. The con-
necting zone of the parent valve still adherent, within which the secondary or
new valve s. v.b was formed. Crossing the centre of the frustule may be seen the
two new connecting zones already considerably developed. On their attaining
mature dimensions the parent connecting zone generally becomes detached.

Frc. 8.—A frustule of Biddulphia turgida, showing the shallow saucer-like valve
in this species, with its two horns and two T-shaped spines.

Fic. 9.—A detached valve of same, showing a minute but very definite

VOL. XVII. F

62 Transactions of the Royal Microscopical Society.

“That, subsequently to this period, no change of configuration
takes place in the siliceous valve, except along its margin, where
fresh secretion of silex may, under certain circumstances, be pro-
duced.”

“That the normal figure of all markings whatever is circular,
or approaches thereto.”

“That these markings are arranged on the surface of the valve

marginal rim which dips into a corresponding channel in the circumference of the
connecting zones of this species.

Fig. 10.—One of the connecting zones of B. turgida, showing the broad
bevelled margin which is received within the body of the valve; the marginal rim
of the latter fitting into the groove &, &.

Fig. 11.—The connecting zone of B. turgida seen from its upper or valvular
aspect. The sinuous outline of the bevelled portion is shown, and the two deep
notches n, 7, and recesses r,7, which correspond to the positions of the bases of the
spines and horns. (I have been quite unable hitherto to discover what purpose
is served by the notches, inasmuch as the spines do not project into the interior
of the valve. The presence of the notches would indicate, however, that there is a
communication at these points between the interior and exterior of the structure ;
this supposition being strengthened by the fact that the spines are very distinctly
tubular.—G. C. W.)

Fie. 12.—One of the T-shaped spines more largely magnified to show the two
orifices of its tubule.

Puate CLXXII.

Fie. 1.—A frustule of /sthmia enervis from the middle of a filament, showing
the great depth occasionally attained by the connecting zones of this species
even before the new valves have been developed to any considerable extent. (This
figure is copied from plate xlviii. of Professor Smith’s ‘Synopsis of the British
Diatomacee.’)

Fie. 2.—A frustule of Grammatophora serpentina, showing the two connecting
zones; the right-hand valve having become separated by accident.

Fic. 3.—A frustule of Chawtoceros (from the Indian Ocean), showing the con-
necting zones c. z., c.z.; and a, a, the alternately crossing awn-like processes
(abruptly cut off in the figure) by which the frustules are held together in fila-
ment. 5

Fic. 4.—A portion of a filamentous Desmid from Lower Bengal, viz. Onychonema
uncinatum (Wal.), showing the same kind of alternate crossing of the horn-like pro-
cesses as has just been referred to in Chetoceros. It may be said to be a common
character in certain filamentous species both of the Diatomacee and Desmidiacee.

Fic. 5.—A frond of Micrasterias pinnatifida: f, the constricted portion between
the two segments.

Fic. 5'.—a, a segment of the same which has separated from its fellow by the
ordinary process of division; the new segment n.s. being developed by gem-
mation from the constricted portion.

Fic. 6.—The two valves of a frustule of Coscinodiscus Sol (Wal.). This beautiful
diatom is figured for the purpose of showing the remarkable hyaline and mem-
brane-like ring which surrounds each valve; the ray-like processes being given
off from, and probably secreted through, the minute apertures which are present
around the margin of the valve.

Fie. 7.—T wo “ Sporangial Frustules,” a and 6, of an Hpithemia, formed by the
fusion of the endochrome of either two or four normal frustules. The empty
normal frustules and large sporangial frustules which contain the germs of the
new generation being retained within the gelatinous mass, which becomes a
nidus for the new brood as soon as it is set free from the sporangial frustules. °

Fic. 8.—The “ Sporangium” of a Cosmarium, formed, as in the case of the
Epithemia, by the fusion of the endochrome of two fronds; so that, from first to
last, it may be truly said that the processes of Multiplication and Reproduction in
the Diatomacee and the Desinidiacee are almost identical,

The Development. &c., of Diatomacer. By Dr.G C. Wallich. 63

in a determinate order, according to the inherent tendency of the
species; but that the ultimate figure of the markings is due to
forces exerted upon the young valve, whilst in a yet plastic state
and retained within the connecting zone of the parent valve.”

“And lastly, that the variation in size, and in the degree
of fineness or coarseness of the markings, is, within fixed limits,
dependent on the conditions under which the Sporangial Frustule
gives egress to the germs of the new generation; but that the
ordinary process of division is, of itself, sufficient to bring about
great variation when operating through a long succession of
individuals.”

In the course of my observations, I endeavoured to show why
variation in the size and markings of different individuals of the
same species is not only consistent with, but naturally follows
from the evidence which was adduced. That whilst the total
number of striae upon a valve may remain nearly uniform in every
valve of the same species, the number of strize upon the fractional
part of a valve (say the yooth part of an inch) admits of just as
much variation as the size of the valve, and proceeds simultaneously
with it during division, but not afterwards. That, in all likeli-
hood, the internal dimensions of the connecting zone, by which the
young or new valve is protected during its secretion and consolida-
tion, determine the size to be attained by it; and although the
valve may subsequently receive some additional siliceous deposit,
the whole of its characters, as we see them in the microscope, are
indelibly impressed upon it before or immediately after its libera-
tion. And further, that each of the two connecting zones, which
(as had been pointed out in my paper “On Triceratiwm”) enter
envariably into the formation of every diatom frustule, increases in
depth by secretion of fresh siliceous matter at its free margin only ;
being “thus enabled to slide the one within the other, telescope-
fashion, to accommodate itself, with its fellow, to the increase of
the cell-contents during division ; this feature being most strikingly
Se in such genera as Biddulphia, Amphitetras, Isthmia, and
others.”

In the observations now about to be made, and which form, as
it were, a supplement to those just cited, I propose to bring
together for critical examination any new facts and deductions on
the subject that may have been since then published. I would,
however, mention at the outset that although I still adhere, in
every material respect, to my old convictions on the question
of “markings,” it is neither my intention, nor does the scope of
this paper demand that I should, on the present occasion, allude to
it further than by indicating how far the markings are the result
of constantly or inconstantly acting forces.

The first thing to be done is to show clearly what are the

F 2

64 Transactions of the Royal Microscopical Society.

opinions at the present time entertained by the principal writers
on the Diatomacex, upon the questions about to be discussed.
This done, it shall be my endeayour—l. To denote the extent to
which the conditions invariably attending the development of every
new or “secondary” valve of a frustule that has once undergone
the process of division may operate in modifying its proportions
and its markings. 2. To supply some missing links in the history
and actual functions of the “ Sporangial Frustule.” And lastly, to
inquire briefly how far any modifications, engendered by any or all
of these combined causes, can be regarded as detracting from the
value of the diatom valve as a definite and trustworthy “test” of
the defining power of microscopic objectives.

In the 1875 edition of the ‘ Micrographie Dictionary’ (p. 238), it
is stated that the frustule of the Diatomaceex consists of two usually
symmetrical portions or valves, which are in contact at their
margins with an intermediate piece, the hoop, variable in breadth
according to age, &c., and, when very narrow, forming a mere
junction line, which is called the line of suture. In some, this hoop
is a simple filament; in others, it is broad and marked like the sur-
faces of the valves; whilst in others, again, the hoops are arranged
like the leaves of a book, each with a round or oval aperture
in the middle, so that the cavity of the frustules is divided into
loculi, and the frustules themselves are to be regarded as compound.
During division the hoop undergoes an increase of width, and thus
removes the two valves to some distance apart.* Sometimes the
hoop consists of two pieces, one overlapping the other. The valves
of Melosira and Isthmia are described as gradually separating
from each other during division, and remaining connected by the
simultaneous widening of the hoop. The history and ultimate
fate of the hoop seem to be variable. Sometimes it becomes
solidly silicified, but not much expanded in breadth, and falls off
when the two frustules are complete, allowing them to separate;
this being the case in Gyrosigma (sic), and probably in all the
allied forms. Perhaps the most remarkable development of the
silicified hoop occurs in Biddulphia, Isthmia, and similar forms ;
the new half-frustules, formed inside the hoop, slipping out from
at like the inner tubes from the outer case of a telescope. In
Melosirva, the hoops appear to keep the new frustules united for
some time.

* It will be hereafter shown that the process is strictly the converse of that
which is here described, namely, that the siliceous valves are foreed asunder by
the increase of their soft contents during the progress of division, each of the
connecting zones being of course drawn back by the valve to which it is adherent ;
but, when the separation of the two parent valves becomes extreme, the connecting
zones each increasing by the secretion of fresh siliceous matter at their free over-
lapping edges, as before described. Of course, therefore, it is an error to say that

the valves of Melosira and Isthmia, or any other genus, remain connected through
the simultaneous widening of “‘ the hoop.” —G. C. W.

The Development, &c., of Diatomacee. By Dr.G. C. Wallich. 65

In the latest (1875) edition of Dr. Carpenter’s treatise ‘ On the
Microscope’ (p. 307), the description of “the hoop” is, in every re-
spect, essentially the same as that just quoted from the ‘ Micrographiec
Dictionary.’ But the author adds that, as soon as the newly formed
frustules begin to undergo any increase, “ the valves separate from
one another, and the cell-membrane, which is thus left exposed,
immediately becomes consolidated by silex, and thus forms a sort
of hoop.” Indeed, so evidently is this portion of the structure
still regarded by Dr. Carpenter as single, that, whilst in the letter-
press describing the woodcut of Biddulphia pulchella (at p. 313),
no allusion of any kind is made to the double nature of the
connecting zone, the characteristic nature of the appearances pre-
sented by the overlapping margins have been very fairly depicted
by the artist. The same singular oversight is repeated with regard
to the distinct appearance presented by the overlapping zones in
the woodcut of Grammatophora serpentina (at p. 323), a diatom
in which, considering its comparatively small size, the true com-
position of this portion of the structure is very readily discernible.

“In Melosira,” Dr. Carpenter continues, “and perhaps in the
filamentous species generally, the hoop appears to keep the frus-
tules united for some time. This is, at first, the case in Bid-
dulphia and Isthmia, in which the continued connection of the
two frustules by its means gives rise to the appearance of two com-
plete frustules having been developed within the original; subse-
quently, however, the two new frustules slip out of the hoop, which
then becomes completely detached, and the same thing happens
with many other diatoms, so that ‘the hoops’ are to be found in
large numbers in the settlings of water in which these plants have
long been growing.”

And finally, Dr. Carpenter mentions that Professor W. H.
Smith (U.S.), in the second part of his “ Memoir on the Dia-
tomacez,” published in ‘The Lens’ (in 1872), regards the
Diatomaceze as siliceous boxes, with one portion (the cover)
slipping over another, as in Pinnulariw, or with edges simply
opposed, as in Fragillariz. In the formation of the new valve
the new part, which slips out from the older, is somewhat
smaller, . . . . the part which slips out carrying away one of the
old valves ; and by further self-division, the new valve becomes
smaller and smaller, as stated by Braun. At this period conjuga-
tion takes place, and a return to the normal condition of the
original large frustule by the formation of a Sporangial frustule
double the size of the parent frustules (op. cit. pp. 314, 315).

Thus far it has been my particular aim to quote, as nearly as
possible in the original words, the opinions expressed in two of the
most recently published standard works on microscopic subjects,
regarding conspicuous and important portions of the frustular

66 Transactions of the Royal Microscopical Society.

structure, and still more important, though certainly far less intelli-
gible, vital processes in these organisms, with a view to show how
singularly vague and unsatisfactory these opinions are. For the
purposes of my argument, it is necessary that I should now, for a
time, invite attention to the observations of a distinguished
naturalist, whose judgment on questions of this kind, based as
it invariably is on patient and conscientious research, must always
command respect, even when it does not happen to be altogether in
unison with one’s own opinions.

In a paper “On the Diatomaceous Frustule and its Genetic
Cycle” (‘ Annals and Mag. Nat. Hist.’ January 1869), Dr. J. Denis
Macdonald wrote as follows:

“ Having consulted the works of various authorities on this
subject, I find the views expressed in the writings of Dr. Wallich
(particularly in his paper ‘On Triceratium, vol. vi. ‘ Quart.
Journ. Mic. Se.’ (1858), p. 242; and ‘On the Development and
Structure of the Diatom Valve, vol. viii. ibid. (186V), p. 129),
most in accordance with my own independent researches. Dr.
Wallich appears to have been the first to set forth clearly that the
middle piece or ‘zone’ consists, while the frustule is intact, of two
distinct plates, the one received within the other; and that the
growth of such plates can only take place at the free margins, or
those which are not connected with the valves; and he has also
shown how the capacity of the frustule may be augmented, at least
in one direction, by the sliding out of the plates or ‘rings,’
telescope-fashion, to accommodate themselves to the increase of the
contents during division. . . . Dr. Wallich, I think very success-
fully. refutes the idea of a continuous growth of the diatomaceous
frustule, the fact being, as he states, that ‘ variation in the size of
the valve and the number of its striz’ (in any fractional part of
an inch) ‘ proceed pari passu during the progress of division, but
not subsequently.’ He admits that ‘growth may take place to the
extent of new siliceous matter being secreted along the margins of
the valve, its depth being thereby augmented ;’ but he considers it
highly probable ‘ that the connecting zone, by which the young valve
is protected during its secretion and consolidation, determines the
limits of the dimensions to be attained by it.’ He states, moreover,
that ‘in truth no two valves of the same frustule can be of the
same size, for the new valves, being formed within the connecting
zones of the parent frustule, must be smaller than these.’ This, I
should think, is the essential cause of the great diversity of size
observable in the frustules of the same species being constant and
universal. ... It stands to reason that as the two new half-
frustules are developed endogenously, or within their parents, the
former must be smaller than the latter by the whole thickness of
the siliceous investment; and this will continue to be the case

The Development, &c., of Diatomacez. By Dr. G.C. Wallich. 67

gradatim in the direct line of descent, though of course all the
pullulations successively taking place in the same half-frustule will
be uniformly of the same size, holding the relation of cast to mould
with respect to their developing cell. Seeing, therefore, that the
smaller the frustules of the same species are, the more endogenous
developments must have preceded them, and, therefore, as one
would naturally suppose, the nearer must be the fitness for conju-
gation to complete the genetic cycle, my great difficulty at one
time was to know how the frustules of a given species ever regained
their original size, or where this gradual diminution should end.
But Mr. Thwaites has furnished us with the solution in his im-
portant discovery that the sporangial frustule resulting from the
process of conjugation is much larger than the parent cells... .
Mr. Smith, in his work ‘The Synopsis of the British Diato-
macex, p. 26, says that ‘the increase in the new valves, though
slight, will, however, sufficiently account for the varying breadth
of the bands of the filamentous species, and the diversity in size of
the frustules of the free forms, without obliging us to suppose that
a growth or aggregation takes place in the siliceous valve when
once formed.’ Yet it is actually within the fully formed valve that
the new half-frustule is produced; and if so, it must, as before
stated, be smaller than its parent by the whole thickness of the
siliceous coat. ‘Starting from a single frustule, Mr. Smith goes
on to say, ‘it will be at once apparent that if the valves remain
unaltered in size while the cell-membrane experiences repeated self-
division, we shall have two frustules constantly retaining their
original dimensions, four slightly increased, eight somewhat larger,
and so on in a geometrical ratio.”” “I am afraid” (adds Dr.
Macdonald) “ that this doctrine of a geometrical increase in the size
of the frustules will not stand the test either of fair theoretical
induction or comparison with natural fact; for although there 1s
truth in a gradual diminution, even this does not take place in a
geometrical ratio, which, in the nature of the case, can only apply
to number, not to size.”

In my paper “On Triceratium,” to which allusion has already
been made, | pointed out that in this and many other genera the
connecting zones, which consist invariably of ¢wo pieces, at first
entirely overlap each other, but as the process of division advances,
recede from each other, and whilst receding have the appearance
of three distinct annular portions or rings, the central portion being
less diaphanous than the portion on either side, and its markings
confused, owing to its being, in reality, the overlapping double
portion under notice. This appearance has led to great uncertainty
and doubt in descriptions of the connecting zone, since, from the
transparency of the uppermost layer, the markings on it and the
one below are seen simultaneously. In those genera in which

68 Transactions of the Royal Microscopical Society.

the valves attain a great relative depth, we find not only that the
connecting zones are more largely developed, but that the valves are
furnished with a constricted rim, or groove, to which the margin
of the connecting zone belonging to each valve is attached, as if to
afford a more fixed point of resistance from which it may extend
itself. ji

In Amphitetras and certain forms of Triceratium and Biddul-
phia, I went on to say, the undeviating presence of marginal rows
of puncta on that part of the connecting zone in close proximity
to the suture between it and the valve, proves that the growth of
each half of the connecting zone takes place only at the margin
farthest from the valve to which it belongs. For, were it not so,
the rows of puncta would recede farther and farther from the
“sutures,” as the zones increase in depth, a result which never
follows. Growth takes place in both zones simultaneously, the
actual extent of the overlapping being dependent on the rate at
which the new valves, and endochrome within, happen to be de-
veloped. In the newly detached frustules (notably in such genera
as Amphitetras and Biddulphia), one valve, namely, the newly
formed one, may still be seen enveloped by the half of the connect-
ing zone of the parent frustule within which it was generated ;
this half remaining adherent sometimes for a considerable period.
I believe that a similar structure obtains in nearly all genera,
although more easily traceable in some than in others, owing to
their greater size and bolder outlines and markings. It may be
thus seen in Himantidium, Odontidium, Denticula, Eunotia,
Grammatophora, Amphitetras, Biddulphia, Isthmia, Hydrosira,
Ooscinodiscus, &c. I added, in passing, that the beautifully
executed figures in ‘The Synopsis of British Diatomacex’ show
distinctly the average appearances of all these genera, with excep-
tion of Hydrosira (which was found by me in Bengal after that
work was published) ; but that the author had evidently failed to
recognize either the true structure or important uses of this por-
tion of these organisms.*

Again, in my observations “On the Structure of the Diatom
Valve ” (1860), | dwelt on the share taken in the secretion of the
siliceous valve by the “ primordial utricle,” though admitting that
our knowledge on the subject was singularly meagre. We knew,
for instance, that the frustules of the Diatomacez, like the fronds
of the Desmidiacew, are encased sometimes in a gelatinous in-
vestiture ; and that, in some genera, this investiture is largely

* It is extremely difficult, sometimes impossible, to demonstrate the presence
of the two halves of the connecting zone in the more delicate and minute navicu-
loid and discoid forms; but I have always succeeded in assuring myself that they
are invariably present,—in other words, that there is no such thing as a ‘ hoop,”
in the sense of its being single.

a

The Development, dc., of Diatomacee. By Dr. G.C. Wallich. 69

developed, whilst in others it is not so. But, from the invariable
comparative obscurity of the more delicate markings in all, until
the siliceous surface 1s freed from its soft covering by boiling acids,
I inferred that all extra-frustular structure is secreted by the
“ primordial utricle” through the marginal apertures of the valves,
much in the same way that the epiderm of the molluscous shell is
secreted by the margin of the animal’s “ mantle.” Of its highly
elastic nature there is abundant evidence, and from its retaining its
character unimpaired, it is impossible to doubt its vitality ; and we
are thus furnished with presumptive proof that the invisibility of
the motile and prehensile filaments, whose existence I endeavoured
to demonstrate inferentially, must be due to the same causes that
enable the subtle gelatinous or membranous elastic film of some
forms, as, for example, Bacillaria paradoxa, to defy our most
perfect optical resources. *

It will have been noticed that Dr. Macdonald fully and un-
grudgingly confirmed, on the basis of his own independent observa-
tions, all the leading facts and inferences mentioned in my papers
of 1859 and 1860. Unfortunately, however, there happened to be
two points, which, though almost trivial as touched on by me at
the time I wrote, did not quite meet Dr. Macdonald’s concurrence
when he published his paper of 1869; and these at once assume
importance from the fact of his having referred to them in con-
nection with an elaborate hypothesis propounded by him in rela-
tion to the order of increase of the Diatomacee—an hypothesis
which, if sound, must of necessity have shown me to be wrong on
the points referred to; but, if unsound, would only lend them
additional corroboration.

To render the arguments more readily intelligible, I will at
once state what the two issues really amount to on which Dr.
Macdonald and myself seem so materially to differ. Put in the
shape of questions, they are:—1. Is each connecting zone, as
affirmed by Dr. Macdonald, “ not merely connected, but directly con-
tinuous with the body of its own valve, and therefore essentially a
persistent part of the valve”? Or is it, as I (in common with most
other observers) believe, so far a supplementary portion of the valve
as to become deciduous on some genera, although more or less per-
sistent in others. 2. Are the extreme differences discernible in the
size of the frustules of some species obtained from different locali-
ties, or from the same locality in differing seasons, sufficiently and
wholly accounted for by the successive diminutions in size resulting
from division, as urged by Dr. Macdonald ? Or is there sufficient

* For a detailed account of all the evidence on which these conclusions were
arrived at, I beg to refer to a paper of mine, ‘On the Distribution and Habits of
the Pelagic and Fresh-water Diatomacee,” published in the ‘Annals and Mag.
Nat. Hist’ for January 1860.

70 Transactions of the Royal Microscopical Society.

ground for maintaining, as I think we are quite justified in doing,
that the idiosyncrasy inherent in the “ Sporangial frustule,”
combined with the varying material conditions attendant on vicis-
situdes of climate to which the sporangial frustule is pre-eminently
subject, is a main cause of difference of size in the parent frustules
of these organisms ?

Now with reference to the first question. It is a singular fact
that although the connecting zone constitutes a very important
portion of the frustular structure, it has by no means received the
careful attention to which its characters and uses entitle it in any
really natural classification of the Diatomacex ; and nothing pro-
bably could show more clearly, therefore, how signally these
characters and uses must have been misunderstood.

In ‘The Microscope and its Revelations’ (p. 304) Dr. Car-
penter thus describes the Diatomacex :—“ Like the Desmidiacex,
they are simple cells having a firm external coating within which
is included a mass of endochrome whose superficial layer seems to
be consolidated into a sort of primordial utricle. ‘The eaternal coat
is consolidated by silex, the presence of which in this situation is
one of the most distinctive characters of the group. It is a mis-
take to suppose that the casing is composed of silex alone. For
a membrane bearing all the markings of the siliceous envelope
has been found by Professor Bailey to remain after the removal of
the silex by hydrofluoric acid; and although the membrane seems
to have been presumed by him, as also by Professor W. Smith, to
lie beneath the siliceous envelope and to secrete this on its suriace
like a kind of epidermis, yet the author (Dr. Carpenter) agrees with
the authors of the ‘ Micrographic Dictionary,’ in considering it
much more likely that it ¢s the proper cellulose wall interpenetrated
by sclea.”

Again :—“ The impermeability of the siliceous envelope renders
necessary” (Dr. Carpenter says) “some special aperture through
which the surrounding, water may come into relation with the
contents of the cell. Such apertures are found along the whole of
the line of suture in disk-like frustules; but when the diatom is
of an elongated form, they are found in the extremities only.
They do not appear to be absolute perforations im the envelope,
but are merely points at which the siliceous impregnation is want-
ing, and these are usually indicated by slight depressions on the
surface.”

Then referring to the error committed by Ehrenberg and
Kutzing, of considering the central and terminal expansions of the
median band as apertures, Dr. Carpenter adds:—* There can no
longer be any doubt as to the real nature of these nodules. As
Professor Smith has justly remarked, ‘the internal contents of
the frustule never escape at these points when the frustule is sub-

The Development, &c., of Diatomacee. By Dr. G. C. Wallich. 71

jected to pressure, but’ invariably at the suture, or at the extremi-
ties where the foramina already described exist’ ” (p. 308).

As thus described, but reckoning from within outwards, this so-
called “ simple cell” consists:—1, of the cell-contents or general
mass of endochrome; 2, of the superficial layer of that mass con-
solidated into “a sort of primordial utricle” ; and 3, of the “ proper
cellulose wall interpenetrated and consolidated by silex.” Whilst we
are called upon to believe that, in order to admit of an indispen-
sable interaction between the cell-contents and the medium in
which the organism lives, there actually do exist apertures in stated
parts of the discoid and elongated genera, but that these are, after
all, “not absolute perforations in the siliceous envelope, but merely
points at which the siliceous impregnation is wanting.”

It is not so stated by the author of the above description, but I
presume it is left to be inferred, that the absolutely indispensable
relation between the interior and the exterior of this “simple celi”
is maintained through the imperforate cellulose membrane at the
minute points where the siliceous material is absent, by osmotic or
dialytic action.

Such a combination of structure, mysterious as it certainly
appears, is no doubt conceivable. But I confess that to my mind
it seems so pregnant with incongruity and so incompatible with the
simplicity of Nature’s ordinary methods of going about her work, as
to force on me the conviction that it is in the highest degree impro-
bable. At all events, I venture to say that, by pining our faith to
such a doctrine, we incur the grave risk of sacrificing fact at the
altar of mere hypothesis. Nay, even assuming, for the sake of
argument, the necessity of the case, as here stated, to be met in the
manner suggested ; in other words, assuming that the maintenance
of the life of the organism may be thus provided for, it neither does,
nor can it by any means within our experience, account for all the
extra-frustular phenomena presented to us in these humble organ-
isms. It does not, and, what is more, it cannot, account for the
movements of the diatom, or the secretion of the gelatinous and, in
some instances, highly elastic membrane-like investments which in
some are patent enough to our vision, and in others we are per-
fectly warranted in believing to be present, though as yet we have
failed to render them visible. And, to say the very least of it, it is
in no small degree perplexing to have to accept as truths the exist-
ence of “apertures” that are the moment afterwards said to be no
apertures, but only the exposed points of an imperforate cell-wall!

But inasmuch as the day has long since gone by for ignoring
the logic of cause and effect, I may be allowed to point with a
sense of triumph to the closely analogous case, very recently pub-
lished in the ‘ Proceedings of the Royal Microscopical Society,
namely, that in which the long suspected but never before seen

72 Transactions of the Royal Microscopical Society.

flagellum of Bacterium was revealed to human gaze, through the
untiring perseverance and skill of Messrs. Dallinger and Drysdale ;
and to base on this a confident expectation that it is but a mere
question of time, and the proper use of the all but perfect optical
appliances which our foremost opticians now place at our disposal,
when the motile and prehensile filaments of some of the naviculoid
diatoms, and the elastic investiture of the mysterious Bacillaria
paradoxa, shall be also revealed to us.*

There is, however, another point connected with this subject
that demands careful notice. Dr. Carpenter, in common, I believe,
with every other writer on the Diatomacex, down to a very recent
period, regards the so-called “hoop” as a single solid piece formed
“ by the consolidation of the portion of the cell-membrane which is
left exposed when the valves separate from each other during the
development of the new valves.” t

Now, unless the hoop be really single (which it certainly is
not), it is evident that, in order to account for the admitted length-
ening and simultaneous increase in the overlapped parts which take
place in many of the larger filamentous genera after the new half-
frustules are fully developed, it would be necessary to assume that,
altogether externally to the exposed and consolidated surface of the
inner of the two connecting zones, there must exist, somehow, a
second exposed surface of “ proper cell-wall,” which in turn becomes
similarly interpenetrated by silex. It seems difficult to understand,
however, if this second layer were thrown out, say in the shape of
a fold or projected process of the “ proper cell-wall,’ how it could
be that when once fairly silicified, this could admit of the least
movement either backwards, forwards, or sideways, over the already
formed inner siliceous layer; unless by taking a third bold leap in
the dark, and declaring that, as soon as consolidation was secured,
it becomes a detached but nevertheless integral part of the frustular
structure.

Dr. Macdonald says (loc. cit. ante, p. 8):—“ Dr. Wallich seems
to consider the hoops of the connecting zone quite supplementary
and not essentially persistent parts of the valves themselves, though
often easily separated.” 'This—Dr. Macdonald will, I know, excuse
me for saying—is rather more than I said, and a good deal more
than I, at all events, meant. In speaking of the two zones as
deciduous, I had no intention of conveying the idea that I regarded
them as merely supplementary or other than highly important

* Moreover, if analogy goes for aught, we have analogous extra-cellular
structure ready made to hand, as it were, in the extremely delicate sarcodic
investiture of the foraminiferous shell, which was discovered some five-and-
twenty years ago by Professor Williamson, of Owen’s College, and which I have
myself detected as being invariably present in the Polycystina, Acanthometra,
Dictyochide, and other testaceous oceanic Rhizopods.

+ Carpenter ‘On the Microscope.’ 1875 ed. p. 307.

The Development, &c., of Diatomacee. By Dr. G.C. Wallich. 73

portions of the frustular structure. It has never been my view,
but Dr. Macdonald’s, that “7 is actually within the fully formed
vALVE that the new half-frustule is produced” (loc. cit. p. 4).
For then it might with perfect truth be asserted that the connect-
ing zones are a mere surplusage, which they undoubtedly are not.
What I maintain is that the new half-frustule is formed within the
connecting zone of the parent valve. There is not a whit more
reason for assuming that the new half of the frond of the just
divided Desmid is formed within the parent half from which it is
poured or budded forth, than there is for assuming that the new
half of the diatom frustule is formed actually within the fully
formed parent valve. At all events, I can unhesitatingly state that
such an anomaly has never been witnessed by me during my some-
what protracted acquaintance with both these families. And I would
therefore ask for an answer to this crucial question: If the new
half-frustule of Beddulphia pulchella or Anvphitetras antediluviana
(two diatoms just now selected by me solely as being the giants
of the race) is formed “actually within the parent valve”’—taking
into consideration the fact that, just within and around the margin
of the valves, these diatoms are deeply constricted—how does the
infant valve (after consolidation, of course) manage to squeeze
itself out of the narrow-mouthed cage? Should it be urged that it
escapes before consolidation is begun or completed, it is clear that
the fact is altogether valueless in relation to the question as to
which part of the structure—the parent connecting zone or the
parent valye—determines the dimensions of the new half-frustule.
For, in that case, the moment the young pulpy infant escaped from
its thraldom, its development could only be under the dominion of
the connecting zone; a portion of the structure in which, as will be
presently shown, certain other most interesting peculiarities are to
be found in the genera referred to.

But Dr. Macdonald expresses himself in no ambiguous language -
on the point, for he says (Joe. ez. p. 2), “ Hach of the sliding seg-
ments of the connecting zone is, moreover, not merely connected with
but directly continuous with the body of its own valve, that which is
invaginated being always the younger, having been produced within
the other or the parent valve.” ... “Whatever may be the configu-
ration of the true ends of the frustule, or, in other words, the body
of the valves, the sides or ‘ hoops’ of the two forming the so-called
‘intermediate piece, are, as it were, marginal extensions of them.”

In reply to this statement, I venture to say that few persons
who have studied the Diatomacez as a whole will dissent from the
opposite view, namely, that the “‘ hoop,” be it double or be it single,
is deciduous in the majority of the genera. Indeed, as shown in the
extracts already adduced, there does not seem to be a single autho-
rity, excepting Dr. Macdonald himself, who would maintain that

74 Transactions of the Royal Microscopical Society.

they are, as a rule, persistent throughout the entire life-cycle of
every half-frustule that has undergone the allotted number of
divisions. Moreover, I doubt the possibility of the persistence
of the “ hoop” being demonstrable at all, even were we assured of
its being a fact. But, fortunately, the determination of this point
is quite immaterial in reference to the hypothesis with which
Dr. Macdonald associates it.

His hypothesis hinges (if I interpret it aright) on the validity
of the assumption that the internal sectional] area of the valve, and
the hoop belonging to it, are identica].* My impression is that
their identity, in the sense implied, of absolute continuity, is by no
means a characteristic of the diatom structure.

With the utmost respect for Dr. Macdonald’s opinions, it appears
to me that he has based his inferences, in this instance, far too
exclusively on data supplied by a single group of diatoms; and
that, even as regards that group, he has scarcely apprehended the
structure correctly. It is true that Biddulphia and Isthmia, two
genera specially examined by him as he tells us (loc. cit. p. 1),
were amongst those singled out in my paper as offering the
greatest facilities for the detection of differences in size between
the older and younger valves of each frustule, and for showing
most readily and distinctly the overlapping telescope-tube action of
the free ends of the connecting zones; the entire frustules being
often of such magnitude as to enable us to distinguish the contrast
in the external diameters of the two halves arising from the con-
ditions described. But I stated with reference to Isthmia—and
this, let me observe, is a most important fact in relation to the
argument—that, “although we sometimes meet in that genus with
great variation in the length and breadth of the frustules growing
on the same object” (say an alga), “it would be found that these
marked differences do not always occur in the same filament, but in
' separate filaments; and that frequently the primary frustule, or
rather that valve of the primary frustule by which adhesion is
secured, does not exceed in size the smallest of any of the neigh-
bouring terminal frustules.” T

But, as my entire remarks at every turn testify, I neither sus-
pected nor did I assume the existence of an inviolable order of
decrease such as that propounded by Dr. Macdonald; and for the
best of reasons, namely, that the connecting zone of the primary
valve in Biddulphia pulchella and Amphitetras antediluviana so
often exceeds, in its diameters, the diameters of the valve itself, as
to leave no room for doubt that a secondary or new half-frustule,

* See the passage just quoted, in which Dr. Macdonald describes the perfect
eaty in substance, and in outline, of the connecting zone and its parent

t “On the Structure and Development of the Diatom Valve,” by G. C.
Wallich, M.D., ‘ Quart. Journ. Micros. Science,’ December 1859.

The Development, de., of Diatomacex. By Dr. G.C. Wallich. 75

though secreted within the connecting zone of the parent valve,
may, and actually does, occasionally, excel the latter very consider-
ably in its dimensions.* When it is mentioned (though of this
fact I did not apprehend the full significance until I had reaped the
benefit of Dr. Macdonald’s most valuable observations, eight years
after I wrote on the subject) that the diameters of the outermost
“hoop” not unfrequently exceed those of its own parent valve, by
as much as one-tenth or one-twelfth of those diameters ; whereas
the thickness of the siliceous wall of the connecting zone is so
extremely small as well-nigh to baffle the attempt to measure it at
all; it will, I submit, be conceded that there is strong prima facie
evidence against the invariable operation of such a law as Dr. Mac-
donald tries to uphold.

But this is not all. A cursory examination of a series of
specimens of the two species of diatoms above named will suffice
to explain how (I do not pretend to say why) this seemingly
exceptional character is so marked in them. In both, immediately
behind and encircling the free margin of each valve externally,
there runs a deep channel or groove, which consequently projects,
on the inner side of the valve, into the general cavity, and mate-
rially curtails its sectional outline on that plane. The connecting
zone springs, as it were, from the bottom of this channel, then rises
perpendicularly to it, until well clear of its border ; and then bends
abruptly forward at a right angle to form the true hoop in each
connecting zone. Now so little can the connecting zone in
Biddulphia be said to be “not merely connected but directly
continuous with the body of its own valve,” forming (as Dr. Mac-
donald has it) an exact marginal extension of it; and so prone are
several species of Biddulphia to ring the changes on this part of
their structure, that in b. turgida the margin of the valve, which
is generally perfectly even and defined, actually embraces and
overlaps eaternally the margin of its own connecting zone. In
this species the overlapped part of the connecting zone consists of
a gracefully bevelled and broad brim, which curtails 74s own sectional
outline by as much as one fifth or one-fourth, and abuts against the
inner side of the concave saucer-shaped valve ; the same result being
brought about in B. pulchella, by the deep constriction already
described, in the margin of the valve itself. I would, however,
specially direct attention to B. turgida, on another ground than the
presence of the constriction, which in it is very shallow; namely,
in relation to its at once disposing of Dr. Macdonald’s idea that the

* It is a noteworthy proof of how often the keen eye of the artist is keener
than-the keen mind of the scientific investigator whose researches he is illus-
trating, that in many of the figures in Smith’s ‘ Synopsis’ and in Dr. Greyille’s
papers on Diatomacee, this and other existent niceties of structure are faithfully
portrayed.

VOL. XVII. . G

76 Transactions of the Royal Microscopical Society.

newly formed half-frustule could possibly, in its case, be fully
developed within the body of the parent valve, or even that it
could be secreted in the pulpy state within it. A glance at the
admirable figure of this diatom in ‘The Synopsis’ will at once
confirm this view.*

A similar configuration, but even more conspicuous, may be
observed in B. regina and B. Tuomeyii (a variety of B. regina).
In B. Baileyii the frequent extension of the connecting zones
considerably beyond the extreme point occupied by the faces of the
newly formed valves is very marked. But in this species, as in
B. turgida, the constriction is slight, though sufficiently distinet
to be easily perceptible. Amongst the rarer filamentous genera
showing these characters strongly, may be mentioned Dicladia and
Cletoceros. Indeed, were it not that the presence of the connecting
zone in every diatom furnishes us with a character which is almost
infallible, the true affinities of these two genera might remain
doubtful. The same may be said of Ehizoselenia, in which I
detected the connecting zone, but with considerable difficulty,
owing to its extreme attenuation, and only in the uncleaned state.

As a matter of fact, there is a constriction or notch, into which
the inflected rim of the connecting zone is received, present in
probably every diatom, though much more difficult of detection
in the minute elongated and tabular forms. Hveryone who knows
the Diatomacex is acquainted with the appearance presented in the
front view of their frustules, at the four points or angles where
the connecting zones are in contact with the valvular margin.
The notch always visible in that position is in reality a profile view,
at that point, of the groove and the inflected rim of the connecting
zone that fits into it, being totally distinct from the lateral view of
the terminal nodule which holds a neighbouring position. Here
again I would invite attention to the figures in ‘ The Synopsis,’ as
admirably depicting the structure.

I must here allude incidentally to a very important fact con-
nected with the extra-frustular appendages of the diatom, viz. my
having found that the principal spines (not the cornua) on the
valves of some Biddulphiz, and the spines forming the elegant
coronet on those of Creswellia, are tubular. In this respect they
resemble sponge spicules. But it can be at once seen in B. turgida
that these spines, instead of being secreted in concentric films
around the longitudinal core or axis (which is the invariable mode
of growth in the siliceous sponges), are perfectly homogeneous,
and in this respect assimilate with the Polycystina. In B. turgida

* My observations on these big diatoms were chiefly made at Guernsey in
1858, where they are to be found at depths ranging from half low-water mark
to eighteen or twenty fathoms. I was gratified to find, whilst this paper was

being drawn up, only a few days ago, that the characters referred to are admi-
rably shown in ‘The Synopsis’; notably B. turgida, also a Guernsey diatom.

The Development, &c., of Diatomacer. By Dr.G.C. Wallich. 77

the two principal spines are T-shaped, the base of the T being
attached to the valve; and the tubule (which may be very dis-
tinctly seen in the larger specimens) having its external opening
immediately at the top of the stem of the T, and not bifurcating
so as to open at the two extremities of the cross-bar- of the T, as
would be the case in any sponge spicule. There is strong evidence
in support of the view that, through these tubules, a communication
is established either with the surrounding medium, or, in some
filamentous genera, with the corresponding spines of adjacent
frustules. Indeed, in Creswellia the extraordinary fact presents
itself that every one of the large series of spines forming the
coronary circlets is precisely in apposition with a similar number
of spines in the adjacent frustules. And from the circumstance of
the spines not being tapered but cylindrical, and, if anything,
slightly inflated at the points of union with the adjacent spines,
they very closely resemble in appearance, and are in all probability
identical in function with, the horny-looking processes met with in
some of the filamentous Desmidiacex.* I mention these morpho-
logical resemblances because the more I look into the structural
details of the Desmidiacex and Diatomacex, the more closely do I
find that they agree on all points apart from the degree of con-
solidation, and the nature of the substance producing the consoli-
dation, of their enveloping wall. By far the most important proof,
however, of the close relation between these two families has yet to
be submitted, when I come to treat of the “ sporangial frustule.”

Before passing on to the next section of my subject, I have to
draw attention to an observation of Dr. Macdonald’s, which cer-
tainly appears to me to involve more than he intended—an obser-
vation which, if correct, would form an immovable keystone to his
hypothesis; but if incorrect, as I believe it to be, cannot fail
seriously to mislead. He says (loc. cit. p. 3), “ It stands to reason
that as the two new half-frustules are developed endogenously, or
within their parent, the former must be smaller than the latter by
the whole thickness of the siliceous investment,” &e. &e. And
again (p. 4), “ Yet it is actually within the fully formed valve that
the new half-frustule is produced; and if so, it must, as before
stated, be smaller than its parent,” &e. &e.

I venture to affirm that the new half-frustule is never developed
within the fully formed or parent valve at all; and that it is
invariably developed as an outgrowth from the soft contents,
entirely beyond the free margin and plane of the parent half-
frustule; precisely as the new segment of the Desmid is developed

* The close resemblance here referred to may be well seen on comparing the
figures of Creswellia, on the one hand, and Streptonema on the other, appended to
Dr. Greville’s “ Description of New and Rare Diatoms” (‘ Q. J. M.S. Jan. 1864),

and my papers on “ The Desmidiacew of Bengal” (‘ Annals and Mag. Nat. Hist.’
ser. 3, vol. v. plate viii. fig. 1).
a 2

78 Transactions of the Royal Microscopical Society.

as an outgrowth from the parent segment. In all my experience
I have never seen a new half-frustule so developed; nor do I
believe such an occurrence to be possible ; for, from the very outset,
there is a ‘‘suture line,” and this suture line is nothing more or
less than the embryo connecting zone, which is not a subsequent
interpolation, as it were, but a simultaneous product with the
development of the new valve itself. And, if so, whenever the
parent connecting zone exceeds its own valve in diameter (as I
have shown to be the case frequently in some diatoms), there 1s, of
course, an end to Dr. Macdonald’s deduction from the premisses,
namely, “that the newly formed half-frustule must be smaller than
the parent valve, by the whole thickness of the siliceous invest-
ment, and that this will continue to be the case gradatim in the
direct line of descent, through the course of all the pullulations
taking place successively in the same half-frustule.”

Should further proof be desired of the impossibility of the
parent valve forming a “mould” within which the new valve is,
as it were, cast, it will I think be found in the significant fact
that in several well-known genera of Diatoms, the two valves con-
stituting each frustule are never symmetrical, eacept in sectional
outline where each margin is in connection with its own connecting
zone; the symmetry in this region being obviously essential to
admit of one of the connecting zones slipping accurately (as before
described) over the other. We are thus furnished with what
appears to me to be conclusive evidence that there resides in the
endochrome of these organisms, an inherent and hereditable forma-
tive power of a determinate kind, though by no means so deter-
minate as the force which governs the formation of every crystal.
At the same time it appears certain that accidentally caused devia-
tion from the normal form may be handed down, in direct descent,
from the frustule in which it first originated. But it must be
borne in mind that this does not take place unless the mechanical
or other cause has acted on the connecting zone. Thus it not
unfrequently happens that a sinuosity, or a notch, may be found
in a large number of specimens of a species of diatom collected in
one piece of water, whereas not a single example of it is to be met
with in specimens collected in another piece of water in the same
neighbourhood.

Repropuction.—In the Introduction to the second volume
of ‘The Synopsis of the British Diatomacex, the late lamented
author of that work prefaced a brief account of the “ sporangial
frustules” of certain species with the characteristically candid
admission that, during the three years which elapsed since the
publication of the former volume, no new light had been thrown
on the subject of reproduction, and that the entire process was, in
short, “ too imperfectly understood.”

The Development, &c., of Diatomacex. By Dr. G.C. Wallich. 79

Nearly twenty years have since passed, and yet, strange to
say, these words might with almost an equal amount of truth be
now re-echoed. If this fact is to be regarded as a source of regret
in one sense, it becomes, at all events, a source of congratulation
in another, since it enables me to dive at once into any new matter
that I may have to communicate on the subject.

Unless a number of significant facts, which have come under
my notice in various parts of the globe, and have one and all
seemed to point to the same conclusion, have been wrongly inter-
preted, an extraordinary misapprehension has, from the very outset,
attached to the conception of what the so-called “ Sporangial Frus-
tule” of the Diatomacez really is; and to this misapprehension
may, in all probability, be ascribed the failure on the part of
observers to detect the sequence of results which they looked for as
the natural outcome of a preconceived, but (as I with all submission
conceive it to be) a faulty theory.

If my idea is correct, the sporangial frustule, instead of being,
as heretofore assumed, the primary or parent frustule of a new
and vigorous generation, constitutes, in reality, the expiring phase
in the life-cycle of a generation that is passing away. In
short, it is nothing more or less than the homologue of the
“Sporangium,” that is to say, the Sporangial cet of the Des-
midiacez, which contains and, for a time, shelters- the germs
of the coming generation ; but is itself doomed, on the liberation of
its living contents, to death and immediate decay. So that here, as
in almost every other point, the close resemblance in organization,
and in the methods by which the Nutrition, Multiplication, and the
Reproduction of these two families of Protophytes are carried on,
seems at every step to be more and more firmly established. And I
need hardly point out that the term “sporangial frustule ” becomes
in this case only the more appropriate, since we must regard the
monster frustules, with all their palpable eccentricities of shape and
marking, not as the parent frustules of a new generation multiply-
ing directly by division from it, but as an intermediate frustular
condition, produced, of course, from the fusion of the cell-contents
of a varying number of normal frustules (as described by writers)
and, as before stated, constituting the homologue of the sporangial
cell of the Desmidiacexw. (See back, para. top p. 63.)

My limits will not admit of my now furnishing a detailed
description of the facts on which this conclusion is based. Suffice
it to say that the facts are numerous, and as conclusive as any facts
ean be which it is practically impossible for us to trace out from
first to last, as we can in the case of the Monads and Infusoria.
In these the entire reproductive processes are sometimes begun and
completed in as many hours as they oceupy days in the Diatomaceex.
Mr. Smith, in ‘ The Synopsis,’ speaks of twenty-four hours asa likely

80 Transactions of the Royal Microscopical Society.

period in the latter. According to an American writer in ‘The
Lens,’ whilst the process of fission in the soft parts of the diatom
occupies only from fifteen to twenty minutes, the development
of the valve occupies six entire days. My belief is that even this
is an under-estimate. I need hardly point out, therefore, how
greatly enhanced must be our difficulties in attempting to follow
with our eye,—1, the fusion of the endochrome of the frustules
which unite in forming the sporangial mass or masses; 2, the
gradual development out of those masses of the sporangial frustule
or frustules; 3, the investiture of the sporangial frustules with
the gelatinous nidus in which they for a while rest; and lastly,
the liberation from the sporangial frustules, whilst still retaimed
within the nédus, of the true germs which shortly become the true
parent frustules of the “ coming race.”

For the present I must content myself with stating that the
sporangial frustule is always more or less of a monster, both as
regards dimensions* and outline; rarely, if ever, presenting the
symmetrical outlines so characteristic of these graceful organisms ;
that it is rarely, if ever, perfectly silicified; that the bloated ex-
pression it exhibits is never handed down, as would inevitably be
the case, were it the model upon which the new brood is formed ;
and lastly, that I have never seen the slightest semblance of
division in it, by the formation of two new valves. On the other
hand, such incongruous characters are occasionally to be seen in the
sporangial frustule whilst still in the embrace of the siliceous valves
from which it sprung, as to engender a suspicion that it may be a
Diatomacean cuckoo that has walked into its neighbouz’s nest.

But from the contents of these giant frustules the new parents
of the race arise :—first, in the shape of minute masses of nucleated
endochrome ; these masses enlarging gradually in size till they
attain the normal (but never exaggerated) proportions and outlines
of the species to which they belong ; finally becoming endowed
with their siliceous investiture ; and then, but not till then, earning
the name of parent frustules. I leave it to Sir James Hannen to
decide how far his judgments coincide with the fact that even
before the honeymoon of the two parent valves of the diatom is
over, they part company for ever, and if by the force of fate com-
pelled to retain some bond of union, as witnessed in the fila-
mentous species, they take the precaution of at all events placing
their children and children’s children, even unto the fiftieth
generation, as buffers between them !

But although the true parent frustules are never monstrous (in
the sense of being specially created because Nature is impotent to
restrain the gradual degeneration in size, upon which so much
gtress has been laid, and to make amends for which so much brain

* It sometimes is twice or even thrice the size of the largest normal frustule !

The Development, &c., of Diatomacee. By Dr.G. C. Wallich. 81

power has been expended), there cannot be a doubt that the new
brood may vary very considerably in its dimensions. And it is
here, and here only, as I clearly pointed out (though Dr. Mac-
donald no doubt quite unwittingly misunderstood my words), that
“vicissitudes of season” come into operation. It is, I believe, true,
that mere climate has little if anything to do with the matter.
IT have found almost as exuberant growths of Desmidiacex in Green-
land and Labrador, as in the Tropics. _ It is the extreme and sudden
vicissitudes of heat and cold, of drought and deluging rain, that
are the chief modifying agents which tell upon the expectant
Sporangia. And even in the sub-arctic lands referred to, such
vicissitudes occur, for during a very few hours of the brief summer
day the heat is sometimes actually excessive.

Taking all these circumstances into due consideration, I venture
to submit that from the birth of the diatom to its death, influences
are at work which are, at all events, more than sufficient to render
that mathematical uniformity in the markings of the diatom valve
impossible, which is an essential condition if they are to be used as
test-objects. And I would therefore sum up my observations on
this portion of my subject by repeating one of the opening para-
graphs of my paper “On the Markings of the Diatomacex in
common use as Test-objects,” published in ‘The Annals and Mag.
Nat. Hist. for February 1860:

“Certain diatoms may still be advantageously employed as test-
objects, but assuredly not in the manner hitherto in vogue. In
order to ensure uniformity, or, what amounts to the same thing,
to ensure that the purchaser of a lens of a stated power shall
actually obtain what he desires, it becomes essential that each test-
slide should itself be first compared with some accredited and
universal standard, before being applied for determining the capa-
bilities of any optical combination.”

82 Transactions of the Royal Microscopical Society.

II.—Observations on Professor Abbe’s Experiments illustrating
his Theory of Microscopic Vision.

By J. W. Srepuenson, F.R.A.S., Treasurer R.M.S.

(Read before the Rovat Microscoricay Sociery, January 3, 1877.)
Pruare CLXXIII.

In my opinion, ‘the very important theory of microscopic vision
which has been enunciated by Professor Abbe,* has not received,
in this country, the attention it pre-eminently deserves. The
theory to which I refer, is, that the microscopic images produced by
certain objects of minute detail, such as diatoms, scales of insects,

EXPLANATION OF PLATE CLXXIII.

Fic. 1.—Fine grating used as the object on the stage of the microscope.

Fic. 2—A ppearance presented on removing eye-piece and looking down tube,
showing central and spectral images.

Fic. 83.—Diaphragm with tliree slits in position, shutting out certain spectral
images, and making those produced by coarse and fine lines identical.

Fic. 4.— Appearance presented on examination of object (Fig. 1) when ex-
amined under the latter condition ; fine lines in normal condition, coarser doubled
in number.

Fic. 5.—Diaphragm excluding all the spectral rays from finer lines, and all
except the two adjacent to central beam from the coarser lines.

Fic. 6.—Shows the coarse striz alone; the finer invisible in consequence of
all their spectra being excluded.

Fie. 7.—Diaphragm excluding all spectral rays.

Fig. 8.—No lines visible in consequence.

Fic. 9—Diaphragm excluding all the spectra of Fig. 2, except the fourth of
the coarse and second of fine grating.

Fic. 10.—Appearance presented; coarse lines quadrupled and fine lines
doubled in number.

Fic. 11.—Effect produced by light of extreme obliquity on parallel lines of
such fineness as to have nearly reached the limit of resolvability; the illuminating
pencil at the edge of field, and only the more refrangible rays of spectral image
remaining in the field at the opposite side.

Fic. 12.—Appearance presented in tube by single valve of P. angulatum ;
light central.

Fic. 13.—Fine crossed grating (60°) used as object on stage of microscope.

Fic. 14.—Spectral aspect produced by crossed grating; the spectra within
smaller circle identical in form with P. angulatum, Fig. 12.

Fic. 15.—Diaphragm in position admitting central beam and three spectral
rays; the imaginary lines joining them crossing each other at right angles.

Fic. 16.—Appearance of Fig. 13 under these conditions; the lines crossing
each other at right angles at distances inversely to those of the spectra (,/ 3 ¢ 1).

Fic. 17.—Square grating.

Fie. 18.—Appearance presented in tube.

Fic. 19.—Diaphragm admitting central and one spectral image.

Fic. 20.—Consequent disappearance of all real lines, and substitution of
diagonal lines at right angles to admitted rays.

* A valuable translation, by Dr. H. E. Fripp, of Professor Abbe’s “ Contribu-
tion to the Theory of the Microscope, and the Nature of Microscopie Vision,”
appeared in the ‘ Proceedings of the Bristol Naturalists’ Society,’ new series, vol. i.
part 2.

‘ A
\

C. Stewart del W West &C° tith

-

f
‘e
7

Observations on Prof. Abbe’s Haperiments. By J.W. Stephenson. 83

and other things, are not simply direct dioptrical images, such as
the mere outline of an object, but are the result, in most cases, of
the combination, or fusion together, of the central pencil with
certain secondary images, produced by the interference of those
pencils of light, into which, by diffraction, the incident beam of
light is, in passing through the object itself, resolved; in other
words, that the principal or central beam of light alone is not
sufficient truly to depict fine lines, small apertures, or other minute
structural details, but that, as far as resolution is concerned, two
or more pencils are always necessary to produce the desired effect.
These pencils may, or may not, include the principal or dioptric
beam, but where the latter is excluded the image necessarily
appears on a dark field.

. Further, his contention is, that when from any cause whatever,
whether from the angles formed by the intersection of lines or
the closeness of the lines themselves, whether from the aperture of
the object-glass, or when, by artificial means, the diffraction images,
as seen within the body of the microscope, are made similar, the
microscopic images themselves will be identical.

The diffraction images of a lined object, in focus on the
stage of the microscope, may readily be seen by removing the
eye-piece and looking down the tube-of the instrument. Here,
with the light central, and the lines on the object parallel, the
coloured spectra are distinctly visible, going off on either side at
right angles to the direction of the striz, the most refrangible rays
next to the central beam of light. The latter fact is particularly
mentioned, as it has an important bearing on the limits of visi-
bility and on the photographic reproduction of microscopic objects.

Professor Abbe has supported his views by some very striking
experiments, which appear to me to be a complete practical demon-
stration of the truth of his mathematical deductions; and by his
permission, I propose to exhibit under the microscope this evening
four or five of those which impress me as being the most important,
and therefore the most interesting.

[st Experiment.— The purport of the first experiment is to
illustrate the production of identical microscopic images by different
structures, when, by artificial means, the diffraction pencils arising
therefrom are made similar in number and position, within the tube
of the instrument, as previously mentioned. |

This experiment 1s made on a grating formed of alternately
long and short parallel lines (Fig. 1), ruled with a diamond through
a film of silver, of extreme tenuity, deposited on the under side of
a thin glass cover, and subsequently cemented with balsam to an
ordinary glass slip, the coarser lines being about 1790 to the inch,
and the finer about 3580.

This grating gives rise to two sets of diffraction spectra, when

84 Transactions of the Royal Microscopical Society.

placed beneath the objective, in the middle of the field, the set
arising from the wider portion, being eaactly half the distance
apart of that arising from the narrower, such distances between the
spectra, being inversely proportional to the distances between the
lines themselves.

On removal of the eye-piece these two rows of spectra (Fig. 2)
are visible, one above the other, as the eye is brought to see succes-
sively the air images at the upper end of the tube.

It is obvious, from the figure, that as the wider grating gives
spectra exactly half the distance apart, and therefore twice as
numerous as those arising from the narrower, that the latter may
be made to coincide with the former, in number and position (as
required), by stopping out every alternate ray from the wider
grating, beginning with the first.

This is readily accomplished by placing a stop close to the
back combination of the objective, so constructed that a central
slit will admit the central ray only, whilst another slit on each
side will admit only the second spectrum of the wider and the first
spectrum of the narrower grating (Fig. 3).

On replacing the eye-piece it will now be seen that the micro-
scopic image of the narrower lines remains unaltered, but that the
wider lines have doubled in number (Fig. 4), by an apparent pro-
longation of the shorter lines between them, making the two images
identical, the upper part being distinguishable only from the lower
by somewhat less brightness, which simply arises from the smaller
number of real lines through which the light can pass.

Again, by stopping out all the spectra, except the fourth of
the wider, and the second of the narrower (Fig. 9), the spectral
aspect is again rendered similar in the two cases, and the micro-
scopic images, though changed, will be still found to be identical,
by the doubling of the narrower and quadrupling of the coarser
lines (Fig. 10); but to see this distinctly, with so low a power as
Zeiss’ a, a, the fifth, or E, eye-piece is required.

I should state that, although in this experiment a Zeiss a, a,
with a third eye-piece, has been used, any other object-glass of
about 1 or 2 inch focus would do as well with a suitable stop;
the stop used with the objective mentioned in this experiment has
three slits, each 3, of an inch wide, with the same distance between
them.

2nd Experiment.—In this experiment the same grating is used
as before, with a diaphragm having a single central slit, so ad-
justed (parallel to the lines of the object) that one spectrum only
will be admitted on each side, from the coarser grating, and none
whatever from the finer (Fig. 5); the object of the experiment
being to show that unless one spectrum at least is admitted there
is no power to resolve the lines.

Observations on Prof. Abbe’s Experiments. By J.W. Stephenson. 85

An examination by the eye-piece shows that this is so; by the
reduction of the aperture the finer lines (the spectra of which are
excluded) have disappeared and been replaced by a plain silver
band, the coarser lines appearing in their normal condition, as
anticipated by theory (Fig. 6).

3rd EKxperiment.—This experiment, like the former, illustrates
the necessity of an amount of angular aperture sufficient to admit
some spectral rays; in it the central slit is simply reduced to 35
of an inch, which is sufficient to exclude the spectra of the coarser
as well as the finer lines (Fig. 7). The examination shows that,
- even as far as lines 1780 to the inch go, all resolving power has
departed, the two gratings being replaced by a plain silver band
without any trace of lines.

In all these experiments in which a slit has been employed, it
will have been observed that the sides of the slit are parallel to the
direction of the lines; but it will be found that if the diaphragm is
turned so that the slit is at right angles to the lines, all the spectra
will be readmitted and perfect definition result, proving that it is
the position of the stops relatively to the striz, and not their form
alone, which produces the phenomena.

The ordinary adapter used for rotating the analyzing prism of a
binocular microscope is a convenient instrument for adjusting the
stops, which may be placed at the end of a small tube of a size suit-
able for entering the objective when necessary. The same effects of
duplication or obliteration of lines may be produced on such an
object as Lepisma saccharina by using higher powers with suitable
diaphragms.

The limit of visibility is a direct consequence of the demonstra-
tion that no resolution can be effected unless at least two pencils
are admitted; and as the admission of a secondary or spectral
image is absolutely dependent on the aperture of the objective, it
follows that the resolving power is a function of such aperture, of
which we know the superior limit to be 180°; when the limit
of resolving power with oblique light has been reached, the illumi-
nating ray will be seen at the extreme edge of the back lens with
the spectral image on the opposite margin, as in Fig. 11.

The rule given by Professor Abbe for determining the greatest
number of lines per inch which can be resolved by oblique light
will be found (taking any given colour as a basis) to be equal to
twice the number of undulations in an inch multiplied by the sine
of half the angle of aperture.

As the sine of an angle can never exceed unity, the maximum
will be equal to twice the number of undulations in an inch in that
ray of the greatest refrangibility which will afford sufficient light for
the purpose. With central light, the maximum for any assigned
colour will be equal to the number of undulations in an inch.

86 Transactions of the Royal Microscopical Society.

What that colour should be is incapable of determination gene-
rally, as the capacity for appreciating light varies with different
individuals.

If, for instance, we take 43 in the spectrum as being suffi-
ciently luminous for vision, we find the maximum, as far as seeing
is concerned, to be 118,000 to the inch; but as the non-luminous
chemical rays remain in the field after the departure of the visible
spectrum, a photographic image of lines much closer together than
those named might be produced. _

How little is gained in “ resolving” power by such an excessive
aperture is at once seen when it 1s considered how slowly the
sines of the larger angles increase, a reduction of the angle from
180° to 128° causing a reduction of 10 per cent. only in the
resolving power, with an immense increase in the general utility
of the glass; or, if reduced to 1063°, we still have a resolving
power equal, on the same hypothesis, to 94,400 lines to the inch.

The next experiments are made with crossed gratings, and give
equally important results.

These gratings are prepared by ruling two sets of lines through
silver films as before, one set being ruled on the under side of a
thin glass cover and the other on the slide; the two pieces of glass
with the limes in contact at an angle of 60° are cemented together
with Canada balsam, and of course give rhomboid markings over
the entire structure (Fig. 13).

4th Hauperiment.—The object of the first experiment with
crossed gratings is to show that with a certain arrangement of the
incident light both sets of real lines disappear, and are replaced
by one set of perfectly distinct spurious lines parallel to a diagonal
of the rhombic figure (Fig. 14). This is effected by using a single
slit stop, with the slit in the direction of one of the diagonals, when
the spurious lines will appear parallel to the other diagonal, and
therefore at right angles to the slit.

If a crossed slit, as in Fig. 15, is used, two sets of spurious
lines willappear at right angles to each other (Fig. 16), although
the real lines, from which they originate, are at an angle of 60°.
The reason of this will be at once understood, from the previous
experiments, to arise from the admission of two sets of spectra,
the directions of which are parallel to the diagonals.

An experiment identical in principle is shown on a rectangular
grating, Fig. 17, in which with a slit admitting one spectrum, such
as is seen in Fig. 19, both sets of lines (vertical and horizontal)
disappear, and are replaced by one set (Fig. 20) intersecting the
squares formed by the real lines, and therefore closer in the pro-
portion 1 : 4/2.

5th Eaperiment.—The object of this experiment, which is per-
haps the most important of all, is to show that with only one row

Observations on Prof. Abbe’s Kxperiments. By J.W. Stephenson. 87

of spectra, the structure of such an object as that under consideration
is absolutely indeterminate.

In this experiment the slit diaphragms are entirely discarded,
and the crossed grating is examined with a simple circular stop,
which is used merely for the purpose of so reducing the angle of
aperture that the first row of spectra only shall be admitted.

The illumination is central, and an examination of the interior
of the tube shows seven pencils of light, the bright dioptric beam
being in the centre of the field, with six equidistant spectral rays
around the margin.

Let it now be clearly borne in mind that we are about to
examine a structure which we know to be entirely composed of
distinct rhombic markings.

On replacing the eye-piece for this purpose, we see hexagonal
markings over the entire field, as in Plewrosigma angulatum, and
this effect has been produced by simply so reducing the aperture
relatively to the fineness of the object, that the first spectra only
are admitted.

From this microscopic image we can infer nothing as to the
real structure of the object under examination; we know it to be
rhombic, but it appears to be hexagonal.

But the bright central beam and six coloured spectra which
have produced this result, are identical in aspect with that pre-
sented by a single valve of P. angulatum with central light.
Compare Fig. 12 and the inner ring of Fig. 14.

This diatom with central light, under the highest powers and
with the largest apertures, necessarily presents the same spectral
appearance, in consequence of the fineness of the striz, or holes
(whichever they may be), the dispersion being too great to admit
the second row of spectra.

It has now been proved that, with the means employed, no
definite inference could be drawn of the real structure of the arti-
ficial object, and it is equally certain that this demonstration will
apply with equal force to the valve of P. angulatum, the hexagonal
markings of which may, to use the words of Professor Abbe, arise
from “two sets of lines, or three sets of lines or isolated apertures
of any shape in the object itself.”

If it were possible to admit the second row of spectra, a nearer
approach to a knowledge of the true structure would be obtained,
as the larger the number of diffracted rays admitted, the greater
the similarity between the image and the object, the keystone
of the theory being that “the interference of atu the diffracted
pencils, which come from the olject, produces a copy of the real
structure,’ as in a dioptrical image; but this, as has been abun-
dantly shown, is rendered impossible by the great dispersive power
of many fine structures.

88 Transactions of the Royal Microscopical Society.

Further illustrations of the formation of hexagonal markings
may be found on the same diatom.

On bringing into focus a good specimen of P. angulatum flat
and with distinct-looking lines, using a broad beam of central light,
the six diffraction spectra before alluded to may be distinctly seen
within the margin of the back lens of the objective (Fig. 12). Any
two adjacent spectra combined with the central cone of light will
form an equilateral triangle, and produce the well-known hexagonal
markings; but as any other pencils forming an equilateral tri-
angle will also produce hexagonal markings, a new set on a dark
field may be formed by excluding the central and each alternate
diffraction ray: the sides of this triangle being longer than in the
common figure, in the proportion of ,/3: 1, the new hexagons
will be three times as numerous as those usually seen, and with
their sides at a different angle to the median line. The three
pencils producing the interference in this case are g, ¢, e, or b, d, f,
and the hexagons will have their sides normal to the axis of the
scale, not parallel as in the common image. Not only is this so,
but it follows from the theory that there must be visible three
other sets of lines, bisecting the angles between the common lines,
and corresponding to the combinations of the spectra, g, ¢, or f, d—
b, f, or c,e—b, d, or g,e. All these phenomena may be observed
by stopping off the pencils which are to be excluded. It is easy to
get the lines bisecting the angles of the common rows, one after
the other, and of these one set parallel to the axis of the scale.
For that purpose oblique light must be used, and the central beam
and one of the peripheral rays must be stopped out, leaving for
instance b and f, or ¢ and e (i. e. two spectra parallel to the median
line).

In conclusion, I can only express my sincere regret that Pro-
fessor Abbe’s recent visit to London took place during our recess.
Had it been otherwise, the Society would have been gratified by
an account of his most important investigations and experiments
from his own lips, very much more perfectly than I can possibly
have done. But my object has been accomplished if, in bringing
before the Society this wonderful contribution to microscopic science,
I have induced the Fellows to appreciate the important considera-
tions to which it necessarily gives rise.

(82a)

NEW BOOKS, WITH SHORT NOTICES.

How to Choose a Microscope. By a Demonstrator. With eighty
illustrations. London: Hardwicke and Bogue, 1877.—The author of
the pamphlet now before us is highly to be admired for his modesty
in concealing his name from the public, the more so as he has really
done good work. We have read all the advice he has given, and we
are perfectly satisfied with it. It is plain and matter-of-fact in its
dealing with the instrument, and, moreover—a circumstance of great
importance—no one man’s manufacture is paraded before the reader ;
in fact, no allusion is throughout made to any maker’s name. But
what is of importance is the fact that we have the opinion of one who
is evidently practically experienced with the instrument he is describing
on subjects which are of immense significance in the selection of a
microscope, and which are nevertheless almost entirely unknown to
the junior student who has to purchase a microscope. Advice is
given in regard to the instrument itself, to its eye-pieces and
objectives, and then to the various additional apparatus, such, for
example, as the condenser, various illuminators, spectroscope, polari-
scope, micrometer, compressorium, dissecting knives, &c. Finally,
some sensible remarks are contained in the last chapter, entitled,
“What ought I to give for a Microscope?” All this matter is nearly
faultless. And especially would we commend the writer’s opinions
on the subject of binocular microscopes. We know that on this point
numbers will be against him, but we still think there is considerable
truth in his objections to these instruments.

And now we have a word to say in a depreciating tone. In the
first place, the illustrations are abominable; in the second, they are
most objectionably situated, half of the eighty being placed on a plate
as the frontispiece, and half similarly situate on an end page of the
pamphlet. Then, again, the system of employing different forms of
type throughout the pages, is a habit for which we must take the
author alone to task, and we must say we think it painful to anyone
who possesses a sensitive vision. In conclusion, we can honestly
recommend the pamphlet to intending workers at the microscope.

PROGRESS OF MICROSCOPICAL SCIENCE.

“ On certain Amebe.’—This is a paper by Professor Leidy, read
in October last before the Philadelphia Academy. He said that one
of the species of Amceba which he had most commonly seen, he took
to be the Ameba verrucosa of Ehrenberg, with which the A. natans of
Perty, and the A, terricola of Greef, appeared to him to be synonymous.
This species he had found in many places: in the crevices of the
brick pavement in the yard attached to his residence, in brick ponds,

90 PROGRESS OF MICROSCOPICAL SCIENCE.

in the ooze of the rocky shores of the Schuylkill River, in sphagnum
swamps, in marsh mud, &c. It is remarkable for its sluggish character ;
and in appearance reminds one of a little pile of epithelial scales, or
fragment of dandruff from the head. Appearing quadrately oval or
rounded, transparent, and more or less wrinkled, or marked with deli-
cate wavy lines; the pseudopods rise in short obtuse mammillary
eminences or wave-like ridges, the summits of which are composed of
transparent ectosarc, while the central portion of the body is occupied
by a thin, pale, diffused, and finely granular entosare. This contains
one or more vesicles, usually one, which very slowly enlarges, and
then less slowly collapses. In addition, as part of the structure, an
oval granular nucleus is sometimes visible. The food contents gene-
rally appear not to be abundant, and often the creature appears to be
empty of food altogether. The character of its food is the same as
with other species of Amceba. It not unfrequently feeds on Dif-
flugians. In a specimen from sphagnum water, from Vineland, N.J.,
last August, he observed an individual, about the 5 of a millimeter,
containing a Difflugia and a Trinema together. As observed by him,
the species ranges from ,', to 4 of a millimeter in diameter. On
the morning of August 27, from some mud adhering to the roots of
Sparganium, obtained the day previously in a nearly dried-up marsh,
at Bristol, Pa., he obtained a drop of material for examination with
the microscope. After a few moments he observed an Ameba verru-
cosa, nearly motionless, empty of food, with a large central contractile
vesicle, and measuring =), of a millimeter in diameter. Within a
short distance of it, and moving directly towards it, was another and
more active Amceba, the species of which he was not positive. It was,
perhaps, the one described by Dujardin as A. limax, by which name,
for the present purpose, it may be called. As first noticed, this Amoeba
was limaciform, 1 of a millimeter long, with a number of conical
pseudopods projecting from the front broader end, which was y', of a
millimeter wide. The creature contained a number of spherical food
vacuoles with sienna-coloured contents, a large diatom filled with
endochrome, besides several clear vacuoles, a posterior contractile
vesicle, and the usual granular entosare. The A. limaz approached
and came into contact with the motionless A. verrucosa. Moving to the
right, it left a long finger-like pseudopod curved around its lower
half, and then extended a similar one around the upper half until it
met the first pseudopod. After a few moments the ends of the two
pseudopods actually became connate (the second time he had observed
this phenomenon), and the A. verrucosa was enclosed in the embrace of
the A. limaz. The latter assumed a perfectly circular outline, and after
awhile a uniformly smooth surface ; but the central contractile vesicle
remained in the same condition, nor did he once observe it enlarge or
collapse. The A. limax now moved away with its new capture, and
after a short time what had been the head end contracted, became
wrinkled and villous in appearance, while from what had been the tail
end a number (ten) of conical pseudopods projected. The A. verrucosa
assumed an oval form, and the contractile vesicle became indistinct,
without collapsing. Moving on, the A. limaaw became more slug-like in

PROGRESS OF MICROSCOPICAL SCIENCE. 91

shape, measuring about } mm. long, by zy mm. broad. The A. verrucosa
now appeared enclosed ina large oval clear vacuole, was constricted so
as to be gourd-shaped, and had lost all traces of its contractile vesicle.
Subsequently, the A. verrucosa was doubled upon itself; and at this
period, the A. limax discharged from one side of the tail end, the
siliceous case of the diatom, which now contained only a shrivelled
cord of endochrome. Later the A. verrucosa was broken up into five
spherical granular balls, and these gradually became obscured and
apparently diffused among the granular contents of the entosare of
the A. limaw. At one moment the five granular balls derived from
the A. verrucosa appeared to be contained in three vacuoles, and the
A, limax had a more contracted and radiate form, and then measured
z's IMm.in diameter. The observation, from the time of the seizure of
the A. verrucosa to its digestion, or disappearance among the granular
matter of the entosare of the A. limax, occupied seven hours. From
naked Amcebe, the test-protected rhizopods were no doubt evolved,
and it is a curious sight to observe them swallowed, home and all, to
be digested out of their home, just as the contents of diatoms are
digested. It was also interesting to obgerve the cannibal Amceba
swallowing another, and appropriating its structure to its own, just as
we might do a piece of flesh, completely, without there being any
excrementitious matter to be voided.

Microscopic Organisms in the Blood of Patients suffering from
Typhus.—The ‘ Academy ’* states that in connection with Obermeier’s
remarkable discovery that the blood in relapsing fever is infested by
a species of Spirochete, it is worthy of note that the same organism
has lately been found in considerable numbers by Manassein f in the
liquid exuding from a fistulous passage communicating with the
antrum of Highmore; pus-cells and crystals of cholesterin were also
present. The patient was in good health ; examination of the saliva
and the blood yielded negative results.

Microscopic Investigation of the Campagna Marsh Poison.—A series
of researches that have recently been made upon this subject is of
intense interest, although we cannot be certain as to the correctness
of the results. The experiments have been conducted by Signori
Lanzi and Terrigi.t “In the endochrome of alge growing in the
Campagna and Pontine Marshes, the former observer has discovered
certain minute dark granules, which increase in number as the alge
die and pass into decomposition. They belong to Cohn’s group of
pigmented spherobacteria (Bacterium brunneum of Schroter), and
yield Monilia penicillata of Fries on cultivation. The so-called
‘pigment granules’ present in the liver, spleen, and blood of
persons who have suffered from malarial diseases are identical with
the above germs. By cultivating such granules from a human liver,
Lanzi succeeded in obtaining a Zooglea. On the basis of these
observations, the writers construct a theory to account for the pre-

* December 9, 1876. :
+ ‘Centralblatt fiir die Med. Wiss.’ October 21, 1876.
¢ Vide Abstract in ‘ Centralblatt, No. 40, 1876.
VOL. XVII. i

92 PROGRESS OF MICROSCOPICAL SCIENCE.

valence of malaria at certain seasons. The marshy pools formed
in the Campagna during the winter months are found to swarm with
alge, both green and colourless, in early spring. As summer ap-
proaches, the level of the water in these pools sinks, owing to
evaporation, and great sheets of dead and decaying alge are exposed
to the air. In these, the spherobacteria grow and multiply; they
may be found in vast numbers in the air to a height of fifty centi-
meters above the surface of the marsh. Swept hither and thither by
the wind, they excite malarial disease whenever they happen to pene-
trate into the human body.”

How Nerves end in Tendon.—The terminations of nerves in muscle
has been carefully studied by Dr. Beale, F.R.S., and also by certain
French and German observers. Their terminations in tendon is a
subject of more novelty. It seems, according to a notice in the
‘ Academy’ (December 9), that the tendon of the sternoradialis muscle
in the frog receives a nerve-trunk of some size near its point of
insertion; the fibres form a network, and end in the tendon. By
employing special methods of examination, Rollett * has sueceeded in
demonstrating that the ultimate fibres terminate in structures which
he terms “ nerve-flakes,” and which present many points of similarity
to the motor end-plates in striated muscle. Their functional signi-
ficance is doubtful. No reflex movement can be produced by stimu-
lating the tendon; hence Rollett concludes that the nerve must
consist of centrifugal fibres.

The Structure of the Optic Baton in Crustacea.—This part, which
may generally be described as that portion of the eye — whether
simple or compound —which extends from the cornea in front to the
optic nerve behind, and which to some extent corresponds to our
aqueous humour, has been fully described in a paper which has just
been read before the French Academy of Sciences by M. J. Chatin.
The author states that extending in the directions already indicated
its appearance is filiform, and it may readily be divided into two
distinct parts; the one external and hyaline—the cone, the other
internal and notably elongated, and to this is given the special name
of baton. Sometimes this latter is of the same diameter throughout ;
at others it is wider at its terminal part, and often is subdivided into
a series of prolongations over the surface of the cone. A pigmentary
matrix surrounds the bdton, and communicates a deep tint to it, a tint
which it is necessary not to confound, as is sometimes done, with the
proper colour of the béton. This in many crustacea shows a series
of transverse stri# and intermediate spaces which have led to the belief
that it had a distinct muscular tunic. This idea the author thinks
originated with the German school, which has generalized too much,
and hence has established as facts what are mere suppositions.
Besides, the work carried on by Germans, to which he refers, has been
chiefly on insects alone, and he believes that he can mention certain
facts which render a belief in the muscular filaments impossible. If

* ‘Centralblatt,’ October 21, 1876.
+ ‘Comptes Rendus,’ No. 22, t. 83.

PROGRESS OF MICROSCOPICAL SCIENCE. 93

we study in the fresh condition the bdtons of various species—of
the crayfish, for instance—and placing them in a drop of the liquid
serum of the body, we very soon find that the brownish colour which
is usually attributed to them belongs to the pigmentary cells with
which they had been surrounded; their colour is absolutely of a very
elegant roseate hue. And this observation is completed by the
following: on the surface of each bdton may be seen lines which
appear to divide it into equal segments, and, prepared in the manner
described above, it may be seen that it separates into discoidal
lamelle. The author records the same facts as having been observed
by M. Schultze in his researches on Batrachians and Fish, but there
must be no homology between the eyes of fish and crustacea. Neither
can we [ Ep.‘ M. M. J.’] conclude with M. Chatin that there is no trace
of muscular tissue in either the eyes of crustacea or fishes, though of
course we admit the former part of the statement.

The cone, which corresponds to the crystalline lens of various
writers, seems to be of a variable appearance (ovoid, prismatic, or
club-shaped), and presents a characteristically refractive power. At
its upper part may be seen the cells of Semper, the importance
of which Claparéde has shown. In some cases one may see towards
the central region a line which has been styled the “ filament of
Ritter.” He thinks that the axile line of the cone should be gene-
rally regarded as indicating the plane of intersection of pieces
originally distinct. The author thus classifies the Crustacea in ac-
cordance with the development of the eye: Astacus, Homarus, Squilla,
Eupagurus, Pagurus, Paguristes, &c., possess batons of a decidedly
superior form, and also may be added Cypridina. But in Typton
Lysianassa and Iscea one observes a manifest simplicity in the batons,
which is still more evident in Notopterophorus and Caprella. It
shows itself more completely still in Hpimeria, and, above all, in
Lichomolgus, where the eye is reduced to a small number of elements
that show hardly any relation to the foregoing.

A Contest as to Priority of Discovery—Those who read the
‘American Naturalist’ will have observed in a recent paper that
Mr. A. 8. Packard, jun., makes a claim which appears to us so just
that we have no hesitation in calling attention to it. In a review
of Dr. Paul Mayer’s recent essay on the “Ontogeny and Phylogeny
of Insects,” Mr. Packard very ably attacks the German writer. He
Says :

“ ‘Ontogeny’ is a term devised by Haeckel, and means the
development or embryonic and post-embryonic changes of the indi-
vidual; ‘phylogeny’ corresponds to its English equivalent, ‘an-
cestry, while the present essay is an attempt to explain the origin
and ancestry of the six-footed insects (Hexapoda) from embryological
and anatomical data. No new facts, as far as we are aware, are pre-
sented by the author, whose essay has, apparently, contrary to usage
in German universities, been crowned not for the original work it
contains, but for the ideas suggested by the labours of preceding
authors.

“ In trying to reconstruct the form of the primitive insect, Mayer

H 2

94 PROGRESS OF MICROSCOPICAL SCIENCE.

insists that it should be done from a study of the winged adult or
tmago, ‘ since a priori we cannot know how far the form of the larva
is original or secondary.’ Other authors have with better reasons
derived the ancestral form from the larva.

“ Mayer’s ancestral insect, then, which he calls Protentomon, had
a body divided into a head, thorax, and abdomen, the latter consisting
of eleven segments, while there were six thoracic feet with five-
jointed tarsi, and two pairs of wings, nine (and perhaps eleven) pairs
of stigmata, a pair of salivary glands, and four excretory organs or
Malpighian vessels, besides a well-developed nervous system, heart,
and an aorta, as usual in existing insects.

“ This hypothetical Protentomon is derived by Mayer from the
worms,* in opposition to the suggestions of Fritz Miller and Brauer
that the insects originated from the Crustacea. This worm, the
parent of the half a million species of insects which have peopled
the globe during the present and past ages, was ‘an unjointed worm,
a common starting-point for the Tracheata and higher worms, and
also a near relation of the ancestral form of the Crustacea.’ This
worm then (1) transformed into a higher organism, with eighteen
joints to its body and at least fourteen pairs of segmental organs,
with perhaps also a masticatory apparatus in the form of jaws; and
was perhaps nearly related to the existing Annelids. (2) A third
step towards the insects was a form similar to the second, but with
ventral and perhaps also dorsal appendages on all the segments; it
was still aquatic. It transformed (3) into a worm with trachee and
with dissimilar segments (the appendages in part beginning to dis-
appear). It lived in fresh water, and is called by our author Pro-
totracheas. (4) This Prototracheas became an Archentomon, still
aquatic, with six feet, and clearly defined head, thorax, and abdomen.
Finally, this fifth form acquired two pairs of wings, was terrestrial in
its habits, and became (5) a Protentomon.

“The author then discusses the ancestry of the different orders
of insects. It is noticeable that in treating of them he begins with
the Hymenoptera and ends with the Neuroptera, following in fact,
unconsciously, the reviewer's classification proposed in 1863. The
Linnean Neuroptera are, however, broken up into several orders, the
author following the usual German system; but Mayer is the first
German author, so far as we are aware, who places the Hymenoptera
at the head of the insects, and the Celeoptera in the neighbour-
hood of the Hemiptera and Orthoptera, where they unquestionably
belong.

‘“‘ Mayer adopts the suggestions of Biitschli and Semper that the
air-tubes of insects originated from the segmental organs of worms,
and, discarding Gegenbaur’s view that the air-tubes were at first
internal, closed air-sacs, he believes that the stigmata or breathing
holes were the first to be formed. It may be objected that as insects
are already provided with renal vessels, it is not necessary to suppose

* This view was advocated by Mr. Packard (though Mayer does not mention
it) in ‘Our Common Insects,’ chap. xiii., entitled ‘‘ Ancestry of Insects ” (1878).
This is the more inexcusable since Dr. Mayer quotes from the essay.

PROGRESS OF MICROSCOPICAL SCIENCE. 95

that segmental organs (also in part excretory) survived in them, and
the inquiry arises whether the air-tubes of insects may not have
arisen from the water-vascular system of the lower worms, which
communicates with two or more external openings. In framing
hypotheses like these, one guess may be as good as another.

“ The author, in a footnote, combats with considerable unction
our suggestion, made in 1867, that the head of insects consisted of
seven segments. It may be observed that at that time we were
influenced by the prevailing views of Agassiz, Dana, and others, who
regarded the ocelli and eyes as homologues of the limbs. This view
was corrected in the ‘Memoirs of the Peabody Academy of Science,’
u. 21, 1871 (a work from which our author quotes), and also in
several other places, including the ‘Guide to the Study of Insects,’
third edition, 1872; and the view that the normal number of cephalic
segments is four was at the same time and in the same places insisted
upon.

“ Dr. Mayer also quotes us as believing that the parts of the
ovipositor are not homologous with the legs, a view we suggested in
1866, but after fresh embryological studies retracted in the above-
mentioned Memoir in 1871 (which the author seems to have read),
and also in other places, notably the essay on the “ Ancestry of
Insects,’ quoted by Mayer, where the view that the ovipositor of the
Hymenoptera, Hemiptera (Cicada), and Orthoptera, as well as the
spring of the Thysanura and the spinnerets of spiders, are homo-
logues of the legs is emphasized.

“ As regards the position of the primitive band of insects, Mayer
ignores the remarks of Dr. Dohrn on its significance in classification,
and considers that the circumstance whether the primitive band is
external or floats within the yolk is of much importance, laying down
the law that ‘insects with an external primitive streak are in general
older than those with an inner. We have previously * objected to
Dohrn’s classification of insects into ‘ ectoblasts’ and ‘ entoblasts, and
would make a similar objection to Mayer’s views, since in weevils
(Attelabus), abundantly proved by Dr. Le Conte to be the oldest of
Coleoptera (a fact ignored by Dr. Mayer, whose genealogical tree of
Coleoptera represents the antiquated classification of this order), we
demonstrated that the primitive band is external, while in Telephorus
it is internal, though our observations are called in question by
Dr. Mayer, who, however, so far as we know, has never published
any observations on the embryology of this or any other animal, the
entire essay being based on facts observed by previous writers.

“ While the essay is interesting and suggestive, the leading idea,
that hexapodous insects first appeared as winged organisms and not
as larval forms, will, we think, be found to have no valid foundation.
We should with as much reason derive the acalephs from an ancestral
free-swimming medusa, and not from a hydra-like form, or the
Amphibia from the tailless rather than the tailed forms, views with
which we imagine few zoologists would agree.”

* “Embryological Studies on Hexapodous Insects,” ‘Memoirs of the Peabody
Academy of Science,’ 1872, p. 15.

96 PROGRESS OF MICROSCOPICAL SCIENCE.

Bacteria of Denmark.—A Danish naturalist, Dr. Eug. Warming,
has been devoting himself to this subject, and has published a paper,
which is given in an abstract of some length in the ‘ Journal of
Botany’ (December 1876). We can, however, only find space for a
portion of this notice. It seems that all along the Danish coast there
is found, during calm weather in the summer months, a red coloration
of the water close to the shore. The cause of this singular phe-
nomenon is referred to Bacterioid masses which cling to Zostera and
seaweeds, and, as might be expected, lose their hold when a storm or
a high tide supervenes, and do not regain their position and appear in
sufficient quantity to colour the water until calm has been restored.
The wet weather of autumn also breaks up the masses, but during the
whole winter it is possible to find plants covered with Bacteria
capable of ready revival, even if their habitat be frozen over. Pro-
fessor Warming has made a study of this subject with his usual care
and success, the results of which—the discovery of several new
specific and varietal forms, and the broaching of theories as to struc-
ture, reproduction, and classification—are noticed in a brief manner.
Sometimes floating masses composed of Clathrocystis roseo-persicina
oceur, but most Bacterioid life is found below the surface; here,
when decomposition has only slightly advanced, one sees principally
small individuals of Monas vinosa, but at further stages many other
red-coloured forms as well as various colourless ones are developed.
A common species is Monas Okenii, of which the Danish examples are
not so deeply coloured as are those figured by Cohn ; marine specimens
are oval or cylindric and straight, fresh-water ones somewhat spiral
in form ; smaller individuals have a single posterior cilium, the larger
one at each end. As to division, Professor Warming believes that
only the small ones exhibit it ; occasionally very long cells were found,
but they were not constricted in the middle, and showed no sign of
division. This does not appear to exhibit a “ zooglea” state. ‘Then
follow various other species, till we come to Bacterium sulphuratum,
under which name are united a number of forms, which together
make up the chief part of the red coloration. The states in which
this appears are:—1. As spheres (Monas vinosa, Ehrbg). 2. As
roundish bodies, usually with a constriction and with granules
grouped at the ends (Monas Warmingii, Cohn). 3. Like Monas vinosa,
but crowded with sulphur-grains (Monas erubescens, Ehrbg.). 4. Long,
narrow, cylindrical, and filled with sulphur-grains (Ahabdomonas
rosea, Cohn). Finally, the series is brought to a close by a spiral
form, the amount of torsion varying from scarcely anything to more
than one complete turn. Professor Warming is at a loss to know
what becomes of the large forms ; he thinks it possible that they form
a sort of spore like Ascococcus. He then describes various other
species, which are pretty fully given by the ‘ Journal of Botany,’
which concludes as follows :—Professor Warming did not succeed in
directly making out the cell-membrane; in the true Bacteria he has
never seen the plasma shrink from the cell-membrane by the action of
reagents, neither has he observed any internal molecular or granular
movement. Sometimes, however, vacuoles are formed round the

~— ee

PROGRESS OF MICROSCOPICAL SCIENCE. 97

periphery, and then the membrane is shown very distinctly. The
grains of the plasma are of two kinds:—1. Strongly refringent, with-
out a well-defined bounding circle; these are merely compacted
masses of the plasma. 2. The ordinary sulphur-grains resemble oil-
drops, and are surrounded by a dark circle. The only form of mul-
tiplication observed was by division. Moreover, the “ zooglea” state
was never seen in salt-water infusions.

Ganglion-cells in the Heart of the Crawfish—A paper has been
read on this subject recently before the Royal Academy of Sciences at
Vienna, by Herr Emil Berger. However, as merely the title is given
in the weekly reports of the ‘ Academy,’ we merely announce the fact
of its publication.

The Seaual Organs of Squilla mantis—This subject, similarly to
the preceding one, has had a communication on it read before the
Royal Academy of Sciences at Vienna, but merely the title is given
in the ‘ Proceedings.’ The author of the memoir was Herr Carl
Grobben.

Dr. Braithwaite’s Book on British Sphagnacee.—Dr. Braithwaite
announces the intended issue to subscribers of ‘ Sphagnacez Britannic
exsiccate,’ which will include about fifty forms, illustrating his recent
monograph, in the choicest dried specimens, both mounted and loose
for microscopic examination. Three Continental species not found in
Britain will also be included. Only fifty copies will be prepared,
in imperial quarto size, price 25s., and the author will be glad to have
the names of those desiring to possess the work. Address, The Ferns,
Clapham Rise, London.

Eriksson on the Dicotyledonous Root.—The December number of
the ‘Journal of Botany, quoting from the ‘ Botanische Zeitung,’ says
that Herr Eriksson’s views on the above subject differ from those of
Herr Holle, which the ‘ Journal of Botany’ gives at some length. It
says that he admits four types of structure:—1. The root-end has
three separate Meristem-tissues, of which the Plerom gives origin to
pericambium, fibro-vascular bundles, and pith; the Periblem acts as
the Meristem of the primary bark-layers, and the Dermatogen or
Dermatokalyptrogen produces the epidermis and root-tip (Haube).
The Periblem of this type arises either from a single cell-row
(Initialenreihe), or from two or from three or more cell-rows.
2. Two Meristem-tissues are present in the root-end ; a Plerom and
a single tissue for the production of primary bark-layers, epidermis,
and root-tip. 38. Only a single Meristem-tissue is found. 4. This
shows Plerom and Periblem, but the latter is external, and builds up
the root-tip from without inwards. Numerous instances of the
occurrence of each type are given, and a fuller treatment is pro-
mised at some future time.

The Ambiguous Position of the Monads.—We have additional dis-
coveries regarding the nature of monads by the Russian naturalist,
Cienkowski. These organisms are on the border-land of the plant
world, and in some cases form protoplasmic nets (plasmodia) like the

98 _ PROGRESS OF MICROSCOPICAL SCIENCE.

plant Myxomycetes. These plasmodia have the function of falling
apart into amceba-like forms, which have hitherto been regarded as
independent animal organisms; hence he thinks that many Amebe
do not represent independent forms, but belong to the developmental
cycle of other and plant-like organisms. Among the monads,
Cienkowski, according to a German correspondent of ‘ Nature,’ has
observed forms in various stages of encystment, self-division, and
formation of colonies. But the most remarkable series of changes
were observed in Diplophrys stercorea, an extremely small cell-like
organism with a yellow spot and pseudopodia at two opposite ends of
the body. These little bodies, observed in moist horse-dung, multiply
by division, and form by union of the pseudopodia long strings in
which separate individuals can glide to and fro. “Thus the boundary
lines which it has so long been usual to draw between plant and
animal organisms, and between the individual groups of those lowest
forms of life, appear more and more illusory, and the supposition is
recommended of a common lowest kingdom of organisms, that of
Protista (Haeckel), out of which animals and plants have by degrees
been differentiated.”

The Life-history of the Salpe.—Mr. W. K. Brooks has published a
very interesting paper on the subject of the development of the Salpe.
In this he traces out their entire life-history, and by the aid of several
euts which he has borrowed from Professor Agassiz fully illustrates
this subject. The paper is in the ‘American Naturalist’ for November ;
and although it contains nothing new, still the following paragraph is
worthy of quotation :—“ The life-history of Salpa may then be briefly
stated in outline as follows: The solitary Salpa is the female, and pro-
duces a chain of males by budding, and discharges a single egg into
the body of each of these before birth. These eggs are impregnated
while the chain-salpe are very small and sexually immature, and
develop into females which give rise to males by budding. After the
foetus has been discharged from the body of the male, the latter attains
its full size, becomes sexually mature, and discharges its spermatic
fluid into the water to gain access to the eggs carried by other
immature chains.”

Microscortcan Contents oF FoREIGN JOURNALS.

Archives de Physiologie, publies par Brown-Sequard, &e. No. 2,
Mars, Avril, 1876.—The first paper is partly a microscopical one, and
is of great physiological importance. It is on “ The Condition of the
Persistence of Sensibility in the Peripheric Ends of Divided Nerves.”
It is illustrated by a series of five coloured plates. This is the only
paper of histological interest.

Journal of Anatomy and Physiology, vol. xi. part 1. Edited by
Messrs. Humphrey, Turner, &c.—This contains several papers of
interest to the microscopist. Among the more important are the
following: “On the Development of the Mamma,” by C. Creighton,
with a plate; “On the Stomach of the Fresh-water Crayfish,’ by
T. J. Parker, with a plate; the second part of the paper “On the

NOTES AND MEMORANDA. 99

Anatomy of the Arms of the Crinoids,” by P. H. Carpenter; “On
the Structure of the Retina,” by Dr. J. C. Ewart and Dr. G. Thin.
This is a most valuable paper, and we regret that it has had to be
reduced in length to meet certain editorial requirements, for it was
before its reduction a useful summary—besides the author’s own
investigations—of the progress that has up to Max Schultze’s time
been made in this direction of microscopic work.

Archives de Zoologie Expérimentale et Generale, publiées sous la
direction de H. de Lacaze-Duthiers. Tome 5. 1876. No. 1.—This
number is much taken up with a zoological paper which has no
microscopical interest. Still it has one important communication on
the development of Mollusks, by Dr. Hermann Fol. This paper,
which is one of a series, is upon the embryonic and larval develop-
ment of the Heteropoda, and is admirably illustrated by four well-
executed and some of them coloured plates. Some of the terms used
seem to be peculiar in their application. ‘Thus the word lecith, and
its compounds proto-lecith and deuto-lecith. Of this the author says:
“ With me the term lecith is synonymous with vitellus; the proto-
lecith is the nutritive substance which the ovule possesses as it leaves
the genital gland; the deuto-lecith is the nutritive material that the
vitellus absorbs only after fecundation and even after division of the
yelk” (apres le fractionnement). This is a long paper (over 30 pp.),
and it follows out the development of certain genera of Heteropods
with much minutiz.—Another paper of considerable value is a review
of Herr R. Hertwig’s paper, “A Contribution to the History of
Acineta-forms.’ The author describes at some length a fine species,
Podophrya gemmipera, which is found in Heligoland on the stems and
branches of almost all the hydroid polyps of the shore. The paper
has an especial importance, from the fact that it combats with
Cienkowski the idea that all the species have a special wall or
envelope enclosing them. He shows that some of them remain naked
through their entire life.

NOTES AND MEMORANDA.

An Objective of Mr. Spencer’s.—Mr. Spenger is an American
maker whose glasses from various circumstances are not likely to come
into the English market. We may therefore quote the following
passage descriptive of one of his objectives which the editor of the
‘ Cincinnati Medical News’ (December 1876) has had in his possession :
—‘ For several weeks we have had in our possession an immersion
zyth, made by Mr. Spencer, marked 160° angle of aperture. In re-
solving power, brilliancy, and sharpness of definition, flatness of field,
and in all the essentials of a pre-eminently fine glass, we have
certainly never met its superior, and very few its equal. All of the
most difficult tests yield to it without the slightest difficulty, and pre-

100 NOTES AND MEMORANDA.

sent a beauty in their resolution that excites the highest admiration.
In comparing its capabilities with a number of the objectives of the
most distinguished makers, it certainly had the advantage. Its focal
length is quite short, and consequently requires very thin covering
glass.”

The Fossil Earth of Richmond, U.S.A.—This appears to be an
exceedingly rich deposit, and it may be worthy of examination by
some of our readers who may have the opportunity of possessing
specimens. The ‘ American Naturalist, of December last, says of it
that the recent excavation of a tunnel by the Chesapeake and
Ohio Railroad Company, through that part of the city of Richmond,
Va., known as Church Hill, has intersected this famous deposit for a
distance of three-fourths of a mile, and afforded rare facilities for
study and the collection of material. C. L. Peticolas, of Richmond,
who has given great attention to the work of obtaining this interesting
material and preparing it for use, describes the stratum as from forty
to sixty feet thick, and situated, nearly level, about fifteen to twenty-
five féet below the level of the city, and one hundred feet above tide
water. Before exposure to the air it is tough and hard, having the
colour and solidity of bituminous coal and requiring to be removed
from the tunnel by means of blasting; but after exposure for some
time it crumbles to a fine powder of almost snowy whiteness, con-
sisting in general of about one-half fine pure clay, one-fourth fine
white sand, and one-fourth fossil diatoms interspersed with many
sponge spicules and a few Polycystina. The abundance and variety
of the fossil forms vary greatly in different parts of the stratum, the
lower levels being the richer.

The Blood-stain Controversy.—We have received a copy of the
‘ American Medical Times’ from Dr. Richardson, with a request that
we would notice a discussion, that it reports, in the Academy of
Natural Sciences of Philadelphia, on the subject of the microscopic
detection of human blood-corpuscles. But it seems to us that Dr.
Richardson is unquestionably wrong in this matter. We have gone
carefully into the subject, with the aid of the magnificent photographs
taken from micrometer slides with blood drops on them, which Dr.
Woodward sent us, and we have not the slightest hesitation in saying
that the blood of man is absolutely indistinguishable, by our present
means, from the blood of the dog or guinea-pig.

The ‘Science-Gossip’ Section Machine bids fair to have a great
reputation. The ‘American Journal of Microscopy’ (January 1877)
reprints the paper with the cut which recently appeared on the
subject in ‘ Science-Gossip ’ itself.

Typical Specimens of the Diatomaceze.—The ‘ American Journal
of Microscopy’ (January 1877) has an important article on this sub-
ject, from which we may quote as follows :—“ We have just received
from Professor Hamilton L. Smith, of Hobart College, Geneva, N.Y.,
the first century of his ‘ Diatomacearum Species Typicex,’ and have
rarely had a greater treat than was afforded by the examination of this
collection. Most microscopists are familiar with the celebrated
‘Typen Platte’ of Méller, an exquisite production of artistic skill.

ee ee ee

NOTES AND MEMORANDA. 101

The collection before us is an effort in the same direction, but is of a
different kind, and in many respects far more efficient and satisfactory.
It consists of one hundred slides (the entire collection will probably
reach five hundred), each containing typical specimens of a species.
With the exception of a few diatoms, such as Arachnoidiscus Ehren-
bergu and Aulacodiscus formosus, there are a large number of frustules
on each slide, and in general there are several genera or species
present. Thus, on the slide before us, marked Aulacodiscus Oregonus, we
find several beautiful specimens of a Hyalodiscus. The value of this
collection, therefore, does not depend upon the mere manual dexterity
exercised (which is the most remarkable feature of the ‘Typen
Platte’), but upon the authoritative’ character of the identifications,
and in respect to this point, we have no hesitation in saying that
Professor Smith stands at the head of living diatomists. Instead of -
a single frustule of each species, carefully reduced to its mere
siliceous elements, we have here a number of frustules; and these,
although perfectly clean, are mounted as nearly as possible in the
condition which they presented while living, unless this should render
them unfit for study. Thus the curious Bacillaria paradoza, instead
of being mounted as a mere assemblage of striated rods, is put up in
that singular, connected condition from which it obtains its name.
From all this it will be seen that these slides are put up to be studied,
not to be merely looked at. 'They are not intended for those who
have never seen a diatom; but, on the other hand, to those who have
even the most elementary knowledge of the subject, they cannot fail
to prove a reliable and easily followed guide in the determination of
species.

ae To gather the material for this collection has been the work of
many years, and has involved the expenditure of much labour and
considerable money. The famous collection of De Brebisson has
been transferred entire to Professor Smith’s laboratory, and has
furnished many rare species, and it might perhaps be safe to say that,
in addition to the Professor’s own gatherings, there are few diatomists
of note that have not furnished him with contributions, either by way
of exchange or otherwise.

“The manner in which the collection before us is put up is worthy
of notice. Each century, or collection of one hundred slides, is
arranged in five pasteboard trays, each slide having a compartment
for itself, and the whole being enclosed in a simple but convenient
pasteboard box. To the lid of this box is pasted a catalogue of the
Species, which are arranged in alphabetical order and numbered.
Hach slide is, of course, labelled, and the label is numbered to corre-
spond with the catalogue. But to prevent any danger of confusion, if
the slides should accidentally lose their labels by exposure to moisture
or otherwise, each slide has its proper number written in with a
diamond, The compartments for receiving the slides are also labelled
and numbered, thus affording the most perfect security against mis-
placement.”

A forth of Collecting Bottle, which appears to be useful, though
we hardly think novel, is thus described by an American journal :—
“Tt consists of a bag or net of some light material, to the bottom of

102 NOTES AND MEMORANDA.

which is attached, by means of a rubber ring, a wide-mouthed bottle.
Any quantity of water may be poured into the bag, and all the objects
which it contains will roll down the sides of the bag and fall into the
bottle, while the fluid escapes through the sides. Delicate objects
are consequently not exposed to pressure, rubbing, or any other
violence, as they would be in an ordinary filter or bag, and the whole
affair is so simple that anyone can make it.”

How to resolve Test-diatoms without any Special Apparatus.—
The Rev. J. Bramhall writes as follows to ‘ Science-Gossip ’ (January
1877), and as he is an authority on the subject, we think his remarks
worthy of quotation :—“ Turn the instrument at right angles to the
sun; close the diaphragm so as to cut off all light below the stage ; or,
if that cannot be done, place a piece of black paper behind the slide.
Bring the light on to the object at the angle which suits it best. This
is easily done by moving the microscope to the right or left. If
necessary, increase the light by the use of the stage or stand bull’s-
eye condenser. That is all. A black ring round the covering glass
is an objection when the cover is small, as it interferes with the light.
To carry out this plan successfully, only two things are necessary—
viz. the sun, and an object-glass, capable of resolving the test, just
before it. It is not intended to supersede the use of the apparatus,
for the sun is far too uncertain an illuminator to be depended upon,
and most men work by night; but it may be useful to those who
cannot afford to purchase any apparatus—not even an oblique illu-
minator, the cheapest of all. I must justify this allusion to my pet
child by stating that I have not, and never have had, any pecuniary
interest in its sale. Having been asked questions as to its capabilities,
I can only repeat what I have before stated, viz. that by its help I
can resolve tests which I never could touch before, though possessing
achromatic condensers, spot lens, &c.”

A new Locality for Amphitetras antediluviana.—Mr. E. D. Mar-
quand states that in the number of ‘Science-Gossip’ for December
1867,* Mr. F. Kitton contributed a valuable paper on the genus
Amphitetras, and amongst others, described this species, together with
two varieties of it: 8, with sides deeply incurved, and angles much
produced ; and y, with five incurved sides. Of the latter (which is
figured) Mr, Kitton remarks: “ This variety appears to be rare, as I
know of only one locality in which it has been found, viz. Hayling
Island, Hants, in which it was rare.” Mr. Marquand has seen no
record of the occurrence of this beautiful diatom elsewhere, and
therefore has much pleasure in adding a second locality, also in
Hampshire, viz. Lymington. A few weeks ago he collected material
from two places, the shore of the Solent below South Baddesley,
exactly opposite Yarmouth; and the bank of the river facing Lym-
ington. The first gathering yielded Amphi. antediluviana, var. B, in
great abundance, but without the typical form; the second produced
var. 6 in less numbers, sparingly intermixed with var. y.

* Vol. iii. p. 271.

Tee

CORRESPONDENCE.

Proressors HELMHOLTZ AND ABBE ON THE OPTICAL
Powers oF THE Microscope.

To the Editor of the ‘ Monthly Microscopical Jowrnal.’

Currron, December 20, 1876.

Sir,—The writings of Professor Abbe, of Jena, on various subjects
connected with optical instruments,* are little or scarcely at all
known in England. But a translation of his essay on the optical
capacity of the microscope appeared, in 1875, in vol. i. N.S. of the
‘ Proceedings of the Bristol Naturalists’ Society’; extracts from which
were also published in the ‘Monthly Microscopical Journal’ of the
same year. An essay of Professor Helmholtz, on the optical capacity
of the microscope, also appeared in the Bristol Naturalists’ Society’s
‘ Proceedings’; and subsequently in the ‘ Monthly Microscopical
Journal,’ in 1876.

In the new edition of Niageli and Schwendener’s excellent mono-
graph on the theory of the microscope and its practical application,
Professor Abbe’s investigations are mentioned in various chapters as
introducing a new phase in the solution of many difficult questions
connected with the optics of this instrument and with the theory of
the limits of the visible. The researches of Professor Abbe are
therein estimated as an important contribution, and a decided step in
advance.

Amongst many instructive discussions I may refer to a particular
result obtained by Professor Abbe, which is dwelt upon with much
force in his essay,f namely, that a large class of objects when placed
under the microscope and illuminated in the usual way not only
transmit ordinary pencils which follow their regular and unaltered
course, but also in virtue of some speciality of internal structure
diffract other rays, so that a mixture of ordinary and diffracted rays
is transmitted to the objective. If then the objective have sufficient
aperture to take in some of the diffracted as well as the ordinary rays,
two sets of images are produced. The general outlines and larger
detail of the object are geometrically delineated by the ordinary rays,
while images of the finer details which caused ditiraction of the illu-
minating rays as they passed through the object, are reproduced by the
reunion of the diffracted rays on the same focal plane as that in
which the geometrical image is formed. And consequently the per-
fection of the complete image would depend in such cases upon large
aperture and perfect focussing function of the system of lenses. If

* For example. His long article in the ‘Jenaische Zeitschrift,’ vol. viii.
1874, on “New Apparatus for Determining the Refracting and Dispersing
Powers of Solids and Fluids,” in which the mathematical principles are discussed
on which his refractometer and spectrometer are constructed.

t+ See ‘Archives fiir Mikroscop. Anatomie,’ vol. ix. 1874; ‘ Beitrige zur

Theorie des Mikroscopes;’ or Bristol Naturalists’ Society’s ‘ Proceedings,’ vol. i.
N.S. 1875.

104 CORRESPONDENCE.

the aperture is not sufficient to admit diffracted rays, the objective
image is devoid of all details minute enough to cause this diffraction,
and which are therefore ipso facto thrown out of the picture. On this
fact is based a number of deductions of the utmost importance to the
theory of the microscope and the limits of visibility, a careful study
of which cannot but greatly tend to clear up our ideas of “ pene-
trating” and “ resolving” powers, and the true significance of angular
aperture.

It is scarcely necessary to remark that the above-mentioned results
have no connection with that theory of diffraction occurring in the
microscope which takes its starting point from the well-known case of
the passage of bright pencils of light through pin-hole apertures,
a case which occurs when an objective of great amplifying power is
employed whose optical aperture is necessarily very minute.

Professor Helmholtz’s essay deals with the question of light as it
passes into, through, and out of the instrument, and the law formu-
larized by La Grange is referred to as a law potentially carrying in
itself many yet unknown applications. La Grange himself only pro-
posed to apply a particular deduction from this law as a means of
determining the amplification effected by the object-glass of a tele-
scope; whilst Helmholtz employed the formula to demonstrate the
relation between brightness of image and amplification in the case of
objectives used in the microscope. The optical law of La Grange
undoubtedly applies to the focussing function by which an image is
geometrically delineated, so that each point in the object is pictured
on the focal plane in an exactly corresponding position, that is, in
symmetrical disposition round its axis; and Professor Helmholtz has
shown that the peculiar photometric relations of the microscope image,
i.e. the relation between amplification and brightness of image
(which, as he expressly states, is not necessarily the same in the tele-
scope), are demonstrable from this law. But it is only when am-
plification is increased and more light needed that the conditions of
diffraction in the microscope are brought into play, so as to present
obstacles to further increase of amplifying power. In a letter pub-
lished in your December number, Dr. Pigott has quoted a passage
from my translation in support of a statement which scarcely needs
refutation. I will, however, quote another, in which Helmholtz ex-
pressly states that “if, perhaps, occasional allusion has been made
to diffraction as a cause of deterioration of the microscopic image, I have
nowhere found any methodical investigation into the nature and amount of
its influence.”

It seems hardly worth while to notice Dr. Pigott’s allusion to
the investigations of the German Professors as a mere attempt to
“popularize” a law of La Grange. No one who has made himself
acquainted with Professor Abbe’s experimental demonstration of the
modes in which objectives of wide-angled aperture form images of
particles in an object which diffract light when placed under the
microscope, will fail to see that the reference to La Grange’s law is
entirely irrelevant; and in regard to Professor Helmholtz’s essay the
demonstration of diffraction of light in its passage through the lenses

CORRESPONDENCE. 105

forms a separate chapter at the end of his essay, in which Helmholtz
makes no reference to the formula discussed in the first part. More-
over, the altered expression of this formula is in no sense a “ popular-
ization.” For to change the terms of a formula, as in the present
case, is not to make it less recondite, but to give it a more subtle
expression, and a more precise definition. Such formule are yet
remote from popular thought !

The cases of diffraction caused by interception of light by close-
drawn lines (as in ruled test-plates) or minute particles in an object
(as in all substances exhibiting minute details of structure) have been
specially discussed by Professors Helmholtz and Abbe, and the con-
sideration of such cases led the latter named gentleman to an experi-
mental verification of the formule worked out by the Professors
separately. This experimental verification I have myself, through
the kindness of Professor Abbe, witnessed, and I propose to give a
short account of the method adopted and its result in the course of a
few weeks.

Finally, it may be remarked that Fraunhofer’s conjecture “ that
an object of less linear diameter than a wave-length can never be dis-
cerned by microscopes as consisting of parts,” which is doubted by
Sir J. Herschel, as not being a necessary conclusion from the pre-
mises, is fairly met by the mathematical formula which places the
limit of visibility at half the wave-length, «= A,, when the divergence
angle a, is equal to 90° (that is, with employment of immersion
objectives). See Helmholtz ‘On the Limits of Optical Capacity of
the Microscope.’

I am, Sir, yours faithfully,

H. E. Fripp.

VARIATION IN NAvICULA RHOMBOIDES.
To the Editor of the ‘ Monthly Microscopical Journal.’

Sir,—On reading the excellent paper by the Rev. W. H. Dallinger
ou the forms and striation of N. rhomboides in last month’s Journal,
one is struck with the evident pains the author has taken to make
distinct and generous reference to those writers on his subject who
preceded him. It is therefore most certain that only by an oversight—
perfectly excusable by reason of the voluminous literature of the
diatom—he has omitted to notice the work of Mr. William Hendry, of
Hull, who, some fifteen years ago, carefully examined and measured
many varieties of N. rhomboides, and came to the conclusion that the
species “is the most variable in its dimensions, irregular in its form

. and possesses a striation more extended in its range than any
other known diatom, thus totally unfitting it to take rank, under any
circumstances, as a test-object.’ * In one direction he even went a
step beyond later writers, by showing, in his tabulated measurements,
that “the numerical striation bears no definite relation to the magni-

* ‘Quarterly Journal of Microscopical Science’ for 1861, p. 231.

106 CORRESPONDENCE.

tude of the shell,”—that it is no uncommon thing to find large valves
with fine markings, and small valves with coarse markings.

It should be understood that in quoting my friend Mr. Hendry,
there is no wish to underrate the very necessary labours of Mr. Dal-
linger : many observers were in doubt concerning the identity of
certain diatoms, and these doubts, I suppose, he has dispelled ; more-
over, there was much, both in matter and manner, to make his paper a
welcome contribution to our Transactions.

In agreeing with Mr. Dallinger that “the microscopist is more
generally concerned with the characteristics of the silicious skeleton
than with the morphology and development” of the diatom, he will
perhaps pardon me for regretting the fact as a misfortune and a mis-
take. I believe that most of us waste too much time in testing our
tools, to the neglect of the useful work which even the worst of them
would enable us to do; while there is a certain large class among us
who really seem equal to nothing else but testing their instruments ;
their highest ambition is bounded by the desire to exhibit dots and
“beads” in competition with their neighbour. These gentlemen only
can answer Mr. Kitton’s question, “ What is microscopical science ?”
It is buying many objectives, measuring and comparing them, boasting
of them, testing, re-testing, and yet again testing them, but never, by
any chance, making an original observation with them.

Yours obediently,
Hewry Davis.

THe Osiigue ILLuMrINaTor.
To the Editor of the ‘ Monthly Microscopical Journal.’

Srr,—The oblique illuminator, which I proposed to name after
my friend the Rev. J. Bramhall, was, I know, a new thing, so far as
he is concerned. On discovering the effective performance of a
reflector parallel to the slide, he at once wrote to me to ask my
opinion of its value, and also to ask whether it was new. I made a
rough trial, and found, with every disadvantage, it resolved strize with
ease, that had formerly taken me some time to bring out; and as I
was not aware that this method of illumination had previously been
described, I wrote a short description of it for ‘Science-Gossip’ and
this Journal, calling it the “ Bramhall Illuminator.”

On June 30, 1876, I received a letter from the Secretary of the
Microscopical Department of the Providence Franklin Society (Mr.
John Peirce), in which he tells me that “Mr. Norman Mason, of Pro-
vidence, R.1., accidentally discovered some time ago identically the
same thing as you describe as ‘ Bramhall’s Oblique Illuminator.’ He
was endeavouring to find a piece of plate glass of uniform thickness.
He used pieces of broken mirrors, strewed wit? Lycopodium, for the
purpose of focussing, and was astonished at the illumination. He
afterwards made use of this illumination for diatoms, and found, as
you state, that the distance of the mirror from the object made quite
a difference. Yours respectfully, John Peirce.”

PROCEEDINGS OF SOCIETIES. 107

On July 10, 1876, I received a letter from my friend Professor
H. L. Smith, of Hobart College, N.Y., from which I quote the fol-
lowing remarks :—“ I have just noticed your account of Mr. Bramhall’s
oblique light illuminator. It is an old dodge over here. I have one,
made over ten years ago; a piece of looking-glass plate with a
ledge.’ It thus appears that this method of illumination has had
several discoverers. It seems to have been known in New York five
or six years before Mr. Van der Weyde of that city described it in
August 1871, as probably a new contrivance; Mr.- Mason, of Pro-
vidence, discovered it “‘ some time ago” (this may mean six or
seven years); and lastly, Mr. Bramhall “discovers” the same thing
about twelve months ago. But leaving the discoverer out of the
question, it is the best and easiest plan for the resolution of striz I
am acquainted with.

Yours very truly,

F. Kirron, Hon. F.R.M.S.

PROCEEDINGS OF SOCIETIES.

Royat Microscopican Society.

Krne’s Cotuece, January 3, 1877.

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 since the last meeting was read
by the Secretary, and the thanks of the meeting were voted to the
donors.

The Chairman gave notice that the next meeting would be made
special in order to vote the suspension of Bye-law No. 27 so far as
related to the office of President. By the law no person should
occupy the office of President for more than two consecutive years,
but in accordance with the unanimous recommendation of the Council
it was resolved to re-elect H. C. Sorby, Esq., to the office for a third
year. To enable this to be done, it would be necessary fur the bye-law
to be suspended.

The Chairman further reminded the Fellows that the next meeting
would be their anniversary, at which the election of officers and
Council for the ensuing year would take place; and the following
“House List” was submitted, it being competent for any Fellow to
propose additional names to be printed with those proposed by the
Council :

As President—H. C. Sorby, Esq.

As Vice-Presidents—Sir John Lubbock, Dr. Lionel S. Beale, Rey.
W. H. Dallinger, and Mr. Hugh Powell.

As Treasurer—Mr. J. W. Stephenson.

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

As Members of the Council—Drs. Braithwaite, Lawson, and Millar ;

VOL. XVII. I

108 PROCEEDINGS OF SOCIETIES.

Messrs. Crisp, Ingpen, Jones, Loy, Ward, Brooke, Bevington, McIntire,
and Palmer.

The Chairman announced that it was necessary to elect two gentle-
men as auditors of the Society’s accounts, and requested the Fellows
to nominate them accordingly. Mr. B. D. Jackson was then proposed
by Mr. Bevington, and seconded by Mr. Thomas Palmer; Mr. Gay
was also proposed by Dr. Gray, and seconded by Mr. Curties.

The Chairman having put it to the meeting, declared Mr. Jackson
and Mr. Gay to be duly elected auditors.

Dr. Wallich read a paper “On the Development, Reproduction,
and Surface Markings of Diatoms,” the subject being illustrated by
large drawings upon the black-board. (The paper will be found
printed at p. 61.)

The thanks of the meeting were unanimously voted to Dr. Wallich
for his paper.

Mr. J. W. Stephenson read a paper “ On some Experiments Illus-
trating Professor Abbe’s Theory of Microscopic Vision.” ‘The experi-
ments were exhibited under the microscope, and illustrated by drawings.
(The paper is printed at p. 82.)

The Chairman, in proposing a vote of thanks to Mr. Stephenson
for his paper, said that it appeared to him that these experiments
clearly showed that diffraction spectra might be produced which
presented all the appearances which they were accustomed to see
when looking at a diatom; but it did not appear to be a conclusive
argument that these appearances might not also be real when pro-
duced by diatoms, and certainly it did not appear to be a necessary
consequence that therefore the diatom’s appearance falsely represented
its structure.

Mr. Stephenson said that Professor Abbe would quite agree with the
Chairman’s remarks; the appearances might be true, or might not;
they left the matter quite undetermined.

Dr. Wallich said there was only one point on which he should
like to make an observation. He thought the first thing to be decided
was what these diffraction images really were. When a diatom was
properly illuminated, and when they could show it and show it again
just as they ought to sce it with different powers, it seemed to him like
reality. The first thing he should like to know would be what
amount of diffraction was sufficient to define a line ?

Mr. Stephenson said that the diffraction images of which Professor
Abbe spoke were produced by the structure examined, and appeared
in the tube above the back combination of the object-glass.

Dr. Wallich said he was taken some years ago, by their dear friend
the late Rev. J. B. Reade, to Dr. Pigott’s to see some diffraction
images, but they all seemed to him like a confused mass of things,
and not at all clearly defined or in any way resembling lines.

Mr. Ingpen mentioned that in the case of Nobert’s bands, the
diffraction lines were as perfectly clear and sharp as those of the
bands themselves.

Dr. Lettsom said that the images shown by Professor Abbe were
perfectly clear, and those lines could be seen as distinctly and clearly

PROCEEDINGS OF SOCIETIES. 109

as any lines produced by angulatum. If Dr. Wallich would favour
him with a call, he should be most happy to show him these effects.

Mr. Stephenson said they had only to drop a piece of card with a
hole in it sufficiently small to exclude the spectra over the back com-
bination, and they would instantly shut out all the lines; the out-
line would be seen, but nothing else. If an ordinary Podura scale
is viewed through a slit placed in a direction parallel with that of
the markings, and afterwards through one placed at right angles
to them, totally different effects would be obtained, and when under
different conditions so many different effects took place it was rather
difficult to say which was correct.

Mr. Stephenson exhibited for Mr. Slack (who was unfortunately
unable to be present from indisposition) a slide containing mercury
globules mounted in balsam, the balsam having been previously
thinned with benzoline and boiled in mounting, there being a pro-
bability that the contraction of the globules in cooling had left a
vacant space round each. Viewed through a micro-polariscope with
prisms crossed, each globule appeared to be semi-transparent (like
horn), and to be marked with a more or less defined black cross.

Donations to the Library since December 6, 1876:

From

Natures Weekliyt nc Mess lua! Poche Pr) east eet Mea te ell oak eee itor:
ANANST EDIE NCEA pee) Ga. coe cat eps sob Me odmaborne Urq l'ae Ditto.
Society of Arts Journal . c Ditto,
Transactions of the Watfor d Natural History Society. " Parts 4 and 5 Society.
Journals of the Linnean Society .. Be Ditto.
Mémoire sur les Caracteres Mineralogiques et Str: itigraphiques, &e.

Par MM. Ch. De La Vallée Poussin et A. Renard .. .. .. M.A. Rénard.
Abstract of Proceedings and Transactions of the Bedfordshire

Natural History Society, 1875-6 .. .. .. «+. «. «. « Society.

The following gentlemen were elected Fellows of the Society :—
Dr. John A. Tulk, M.A.; J. T. Redmayne, Esq., L.C.P.E.; Matthew
Hawkins Johnson, Esq.; and James Spencer, Esq.

Water W. Rzevss,
Assist.-Secretary,

Mepicat Microscoricat Society.

Friday, December 15, 1876.—F. H. Ward, Esq., Vice-President,
in the chair.

Rodent Ulcer.— Mr. Golding-Bird read a paper, illustrated by
drawings and specimens, upon this subject. Having reminded his
hearers of the generally accepted clinical characters ‘ascribed to the
disease, he proceeded to analyze the cases published by the principal
writers upon the subject from the time (1827) of Dr. Jacob, of Dublin.
Referring only briefly to their clinical aspect, he dwelt upon the
descriptions given of the histological appearances, but it was much
to be regretted that so very few of the large number of cases reported
had any thoroughly reliable microscopic analysis.

From this he, however, concluded that the principal English

Re

110 PROCEEDINGS OF SOCIETIES.

authorities are agreed now upon the disease being non-cancerous and
non-epithelial, but a small-celled growth comparable to the edge of
an ulcer rather than to anything else. Some observers make a
special arrangement of the cells into columns or circular aggre-
gations, considering this latter essential: with this the author of the
paper did not agree; he did not think such a precise arrangement
essential, but rather accidental; or if essential to some varieties of
the disease, we did not know yet what clinical distinctions cor-
responded to them. Dr. Warren, of America, Billroth in Germany,
and Ranvier in France, all class the disease under cancers, and
describe the presence in greater or less degree of epithelial infil-
tration, Such a view the writer had from microscopic investigation
not been able to uphold ; and he thought that everything—at least
from the clinical aspect—militated against it. Dr, Warren was the
only writer, as far as he knew, that had insisted upon a peculiar
arrangement of the fibrous tissue. This he had also noticed,

The writer then gave a detailed account of three cases, in one of
which there were two returns of the growth after extirpation, and in
these he had found an excessive infiltration of small round cells,
similar to those of ordinary inflammation rather than to true epithe-
lium; no definite arrangement of the cells; no transition between
them and the epidermis, and no projection unduly of the latter down
into the cellular tissue ; a great abundance of fibrous tissue, formed
apparently from the intercellular material; it lay as much under the
granulating part of the ulcer as under the skin around ; its direction
was mostly ascending towards and at right angles to the free surface.
It seemed to come from bundles, that threw out bold curves of the
tissue on either side, so that under a low power, almost a tree-like
appearance was seen. It is this that is referred to and figured by
Warren. In all cases the great excess of fibrous tissue making its
way where the induration extends, even close under the free surface
of the granulations, was remarkable,

In fine, the author agreed with English observers generally, in
the non-epitheliomatous character of rodent ulcer, but thought that
the great excess and peculiar situation of fibrous tissue as much a
distinctive mark as any peculiar grouping of the cells, and ventured
to suggest that the so-called nests of epithelium described by some
may only have been normal epithelium, e. g. of hair follicles, very
obliquely cut.

Mr. Fred. Durham expressed his belief in rodent ulcer being
a small-celled growth and non-epitheliomatous,

Mr. Giles quoted an instance of normal epithelium having been
mistaken for nests of epithelium in a sarcomatous growth.

Mr. Henry Morris, rather from the clinical aspect of the disease,
considered rodent ulcer as quite distinct from epithelioma, though
not able to say what microscopic diagnostic character it might
possess. He had only that day examined a case of thirteen years’
duration that had excavated the face, and he had found a markedly
tubular arrangement of the cells, similar to the cases described by
Mr. Hulke and referred to in the paper.

PROCEEDINGS OF SOCIETIES. 1

Quexerr MicroscopicaL Crus.

Ordinary Meeting, November 24, 1876.—Henry Lee, Esq., F.L.S.,
President, in the chair.

A paper by Mr. C. F. George, “On a Species of Argas found in
the Roof of Blyborough Church,” was read by Mr. Curties. This was
at first considered to be Argas reflecus, specimens of which had been
found in Canterbury Cathedral, but it was finally determined to be
Argas Fischerii. Its mode of introduction was doubtful, as it might
have been brought in the pine timber with which the roof had been
repaired, or by the bats which sometimes frequented the church. It
was suggested that much interesting information on the subject might
be obtained by the examination of old roofs that were being taken to
pieces. The paper was well illustrated by drawings and specimens.

Mr. Charles Stewart gave a lecture “ On the Histology of Skin,”
in which he traced its development from the simple cell and the
growth and structure of the dermal membrane of sponges, through its
various modifications in echinoderms, mollusks, fish, reptiles, birds,
and mammals. Mr. Stewart’s admirable diagrams in coloured chalks
upon the black-board added to the interest of the lecture, which was
highly appreciated by the members.

Ordinary Meeting, December 22, 1876.—Henry Lee, Esq., F.L.S.,
President, in the chair.

Mr. Henry Crouch read a paper “On Microscopy in the United
States of America,” giving some interesting details of a recent tour in
that country, and of the microscopes, &c., exhibited at the Centennial
Exhibition at Philadelphia. He also exhibited some beautiful speci-
mens of vegetable tissues prepared by Dr. J. G. Hunt, of Philadelphia.
Some of these showed the structure remarkably well by the aid of
double staining with aniline dyes.

San Francisco MicroscoricaL Society.

The semi-monthly meeting of the Microscopical Society was held
in the new rooms, December 7, with Professor Wiliam Ashburner in
the chair.

Mr. H. C. Hyde donated one of Zentmayer’s amplifiers, for
doubling the magnifying power of any combination of eye-pieces and
object-glasses, which was adjusted by him during the evening, and its
capabilities favourably tested.

A letter was read from Mr. Charles Stodder, of Boston, giving
further information relating to the use of Wenham’s reflex illu-
minator; and Dr. F. H. Engels also addressed the Society concerning
a sample of fresh-water diatoms obtained by him in a stream near
American Flat, Nevada, which he sent, asking for an exchange in the
way of marine diatoms, &e.

Mr. G. A. Raymond produced some considerable interest in a
somewhat common curiosity known as jumping beans, which came
from Alamos, Sonora, Mexico, from the fact that he had been fortu-
nate enough to get not only the chrysalis of the insect, the larva of

112 PROCEEDINGS OF SOCIETIES.

which, within the bean, causes the motion, but the perfect insect
itself. Mr. H. Edwards, who was present, stated that he had never seen
the insect before, as they had failed to arrive at such perfection in his
hands, and his idea that it was a coleopterous insect was dispelled, for
the little-winged, moth-like body was one of the Lepidoptera, without
question. The matter was referred to Mr. Edwards for examination
and report.

Mr. Hanks was asked to report on a sample of so-called silver
mud, presented by Mr. G. L. Murdock, and obtained from the silver
springs lately discovered in Wasco County, Oregon. The sample
gives a chemical assay of over $3000 to the ton, and it will be
interesting to see what the microscope has to say about it.

Mr. Hanks presented two specimens of minerals, being gold in
hematite and talcose rock, from the Black Hills, Wyoming, a
peculiarity being noted in the extreme fineness of the gold.

Mr. Hanks also called attention to an interesting mineral which is
only known to occur on the Pacific coast. It resembles scheelite, in
which a part of the lime is replaced by oxide of copper. Professor
Whitney, who first described it, has named it cupro scheelite. This
mineral affords an example of the importance of the microscope in
determinative mineralogy. When first discovered it was thought to
be a mechanical mixture of scheelite with some copper mineral ; but
upon a careful examination under the microscope it was found to be
perfectly homogeneous. Subsequent discovery of crystals of cupro
scheelite proved it to be a distinct and new species, as shown by the
microscope. One peculiarity of this mineral is the ease with which
the tungstic acid it contains can be isolated. Tungstic acid, combined
with soda, forms tungstate of soda, the solution of which renders cotton
cloth incombustible. It was suggested by Mr. Hanks that if tungstic
acid could be produced cheaply, the theatrical managers could afford
to prepare the cotton upon which their scenery is painted, and thus
greatly lessen the danger from fire. Cupro scheelite is said to occur
in considerable quantities both in Upper and Lower California.

Mr. J. P. Moore exhibited a number of sheets covered with dupli-
cate impressions of a drawing made from the microscope, with a new
device, known as Zuccato’s papyrograph. He explained the simple
process of the manipulation of the pen, ink, and peculiar paper on
which the drawing is made, and suggested that scientific and other
papers could be rendered more valuable by this system of multiplying
the drawings of objects which might be referred to in any paper read
before the Society.

voscopical Journal. Marl 1877. P1.CLXXIV.

Try ee yeaa iy fy sy
| heMonth LY iIVi1Cr
——_——__—_—_

Grains of sand,clay &e.
Magratied varvusly from 30 to 3O00CO linear.

THE

MONTHLY MICROSCOPICAL JOURNAL.

MARCH 1, 1877.

I.—ANNIVERSARY ADDRESS OF THE PRESIDENT,
H. C. Sorsy, F.R.S., &.

(Delivered before the Roya Microscorican Society, February 7, 1877.)
PuaTeE CLXXTIV.

TABLE OF CONTENTS,

Introduction.
The Application of the Microscope to Geology.
Structure of Stratified Rocks.
Preparation of the Objects.
Mounting Deposits in Balsam.
Visibility of the Objects.
Object-glasses used.
On the Microscopical Character of Sands and Clays.
Origin of the Material, viz. :

Quartz.

Quartz in Granite.

Quartz in Schists.

Mica, &e.

Hornblende and Schorl.

Felspars.

Pumice.

Tron Oxides.
General Conclusions,
Sorting of the Material.
Practical Application of the above-described General Principles.
Identification of the constituent Minerals, viz. :

Quartz.

Calcite, &e.

Mica.

Hornblende, &e.

Felspars.

Kaolin, &e.
Application of similar Principles to thin Sections of Rocks.
Application of the above-described Principles to Special Cases, viz. :

Millstone Grit of South Yorkshire.

Sand of the Egyptian Desert.

Sand derived from Schists, Clays, &c.

Volcanic Ash Beds in British Strata.
Conclusion.

Introduction.

BeE¥ForE commencing the special portion of my address, I think I

may venture to congratulate the Fellows on the general condition

of our Society, and on the proceedings of the past year. We have

had a considerable number of valuable communications, followed by

very satisfactory discussions. For my own part, I have been
VoL. XVII. K

114 Transactions of the Royal Microscopical Society.

eratified with the fact that so many of these papers were devoted
to important general questions, and were not confined to individual
observations, having no apparent bearing on any of our great
scientific theories. After the reading of these papers I in most
cases endeavoured to express my own opinion on the various sub-
jects, and I therefore think it less desirable to again pass them in
review, than to direct your attention to a special branch of research
with which I have been occupied during the last half year.

The Application of the Microscope to Geology.

Our late distinguished Honorary Fellow, Ehrenberg, was the
first to apply the microscope to any considerable extent to the
study of geological questions. He, however, directed his attention
mainly to the organic constituents of rocks. The general structure
of hard stony masses has lately been much studied both in England
and on the Continent, especially that of various igneous rocks, or of
highly altered strata which more or less closely resemble some
of them. So far as I am aware, very little has been done in the
application of the microscope to the investigation of the nature and
origin of loose and unconsolidated sands and clays. I was led to
study these in full detail, because it appeared to me desirable to
thoroughly understand the characters of the raw material before
attempting to speculate too freely on the nature, extent, and
cause of the changes which have subsequently occurred during
consolidation or metamorphism. I was also led to examine cer-
tain questions more fully on account of having undertaken to
investigate and describe the mineral constituents of the deep ocean
deposits brought back by the ‘ Challenger.’

Seeing, then, that this great subject had hitherto been so much
neglected, and is yet the very foundation of our knowledge of the
history of those rocks, which constitute a large part of the acces-
sible framework of our globe, it appeared to me desirable in my
address this evening to attempt to treat this subject in a systematic
manner, combining together some well-known facts with others
that have perhaps attracted little or no attention, in order to make
the whole more continuous and complete. Time will not, however,
allow of my entering into full detail, and will compel me to confine
my remarks to one principal question.

Structure of Stratified Rocks.

The study of the microscopical structure of stratified rocks is
very naturally divisible into two very distinct questions, viz. the
nature and origin of the materials which were deposited, and
the changes which have occurred since deposition; but on the
present occasion I must confine myself almost entirely to the former
of these two divisions.

Anniversary Address of the President, H.C. Sorby, F.R.S. 115

In examining each particular deposit two different questions
present themselves. It is necessary, in the first instance, to
identify as accurately as possible the mineral nature of the various
large or smaller particles, and in the second place to determine as
far as is possible the true nature of the rock from which they were
originally derived. Thus, for example, if we were studying some
modern sandy mud, it would be necessary to identify the grains of
quartz, felspar, mica, and hornblende, and the minute granules
derived from more or less completely decomposed felspar; but
after this preliminary step another important question presents
itself. It is very desirable to determine the nature of the pre-
viously existing rocks, which, when decomposed and broken up by
various chemical and mechanical actions, gave rise to the particles
of the mud under examination. When this can be successfully
accomplished, the history of a comparatively modern deposit may
be indefinitely extended into remote past epochs. In a similar
manner the study of the ultimate constituents of the very oldest
stratified rocks might enable us to form some opinion respecting
the nature of still earlier rocks, of which no other record may
remain. If this could be done successfully we might, as it were,
sometimes trace back the genealogy of our globe a generation or
more earlier than by other means. This appears to me a question
of so much interest, and its solution so dependent on microscopical
investigations, that I venture to bring it before you in some detail,
even although the conclusions have a more direct bearing on
geology than on those branches of science which usually claim the
attention of this Society.

Preparation of the Objects.

When stratified rocks are sufficiently hard and consolidated to
be made into thin and partially transparent sections, many facts
may be better seen in slices cut perpendicular to the stratification
than by attempting to disintegrate the rock and examine the
detached particles. It would, however, often be difficult or almost
impossible to prepare satisfactory thin sections of many modern or
ancient deposits, and it thus becomes necessary to study them in
another manner. If the particles are firmly held together by
calcic or ferrous carbonate, or by any of the oxides of iron, they
may be set free by the action of cold dilute hydrochloric acid, or by
a stronger hot solution; but if, as often happens, the rock is con-
solidated by means of silex, this cannot be accomplished. Violent
mechanical crushing must be avoided, since it would give rise to
false results by fracturing the constituent grains. Such an amount
of crushing as can be effected with a small stiff brush made with
bristles does, however, appear to be admissible, since it could
scarcely break the separate fragments. Even in the case of

K 2

116 Transactions of the Royal Microscopical Society.

modern unconsolidated clays and muds it is very often difficult
to completely separate the ultimate particles when the material has
been dried. The finer granules cohere together and form compound
larger granules, which might easily be confounded with objects of
a different nature. It is therefore often desirable to mix up small
quantities of such material with a little water by means of a small
and somewhat stiff brush, so as to separate the detached granules
without breaking up any truly compound grains. A portion of
this may then be sufficiently diluted with more water, placed on a
glass slip with a projecting ledge, and covered with a piece of the
usual thin glass. By this means the larger particles are seen
separate, but the smaller have a very great tendency to mass
themselves together by a sort of mutual cohesion. Since the index
of refraction of the various grains is in all cases considerably greater
than that of the surrounding water, the outline of even the most
transparent constituents is well seen, but at the same time this
difference in refractive power may make it impossible to study the
internal structure or optical characters of the larger grains. This
difficulty is overcome by mounting in Canada balsam, which has so
nearly the same index of refraction as that of many of the consti-
tuent grains that, even when their outline is as irregular as possible,
light passes through them almost as though they were thin slices
with parallel polished surfaces. This enables us to study the
external staining, internal structure, and optical characters to
great advantage, since they are not interfered with by any dark
shading due to the bending of the light out of the line of vision.
When examined in water there is no difficulty in recognizing
extremely minute granules of the kaolin of clays, whereas when
mounted in balsam they may be almost or quite invisible: but
this very circumstance is of great advantage in observing certain
facts, since by making them invisible other objects may be dis-
tinctly seen which otherwise would be completely hid by the sur-
rounding granules. ;

Though, in order to obtain a knowledge of the general cha-
racter of the deposit and the variation in size and relative
abundance of the different constituents, it is best thus to examine
deposits as a whole, a mixture of very coarse and very fine par-
ticles makes it difficult to study in detail either to perfection. It
is therefore often desirable to separate the coarse or finer sand
from the still finer granules of clay, which may be effected by sus-
ending the material in water, and allowing the sand to subside,
whilst the whole is gently agitated so as to prevent the cohesion of
the particles into the compound grains described in a subsequent
part of this address.

Anniversary Address of the President, H.C. Sorby, F.R.S. 117

Mounting Deposits in Balsam.

In mounting the loose sandy deposits in Canada balsam I have
found it a great advantage to adopt the following plan :—Having
placed a very small quantity of dissolved gum on the glass plate,
the requisite amount of the deposit is taken and mixed with the
gum and sufficient water to make it easy to separate the grains
and spread them uniformly over the space which will afterwards
be covered by the thin glass. The water is then allowed to
evaporate slowly, and though much of the gum collects round the
margin, by properly regulating the quantity originally added
enough remains under the larger grains to hold them so fast that
they are not squeezed out with the excess of balsam. More gum
than is sufficient for this purpose should not be used, since it may
make itself too conspicuous in the object. When the proper quan-
tity has been used, its presence can be detected only at the under
surface of the grains, and in that situation does not in any way
interfere with the study of the object. Independent of the conve-
nience in mounting, this method prevents the grains from settling
to one side of the object, even when soft balsam is used, which is
desirable, since it penetrates more completely at a lower tempera-
ture into irregularities of the surface and into the interior of
compound grains than when harder.

Visibility of the Objects.

Some of the separate grains, or those enclosed in transparent
minerals, do actually absorb a considerable part of the light trans-
mitted through the object, and are therefore visible as black or
coloured particles, quite independent of the angle of convergence
of the light, and of the aperture of the condenser or object-glass.
Many of the particles are, however, composed of quartz, mica,
felspar, or other colourless and transparent ininerals, and when in
water or balsam are made visible mainly by a portion of the light
transmitted through them being so bent out of its course that it
does not pass up to the eye-piece. ‘This is especially the case with
the more or less curved edges of the grains, and with suitable
illumination they thus show a dark outline. The same principles
apply to fluid cavities in minerals, and to the accompanying bubbles.
The width of the dark margin depends on the difference in the
refractive power of the particle and of the surrounding medium,
and if this difference be small, no such outline may be seen, if the
angle of convergence of the light be at all considerable. Thus, if
the aperture of both the object-glass and condenser is large, and
the grains are mounted in Canada balsam, little or no trace of them
may be visible, but by reducing the aperture their outline becomes
more and more distinct, and the shading greater and greater, until

118 Transactions of the Royal Microscopical Society.

in certain cases it may become so dark as to obscure certain cha-
racters. It is therefore of the very greatest importance to have
the means of varying the angle of deviation from a direct line,
which in ordinary microscope apparatus is the most readily effected
by a diaphragm below the condenser. In the case of very fine
particles of such substances as pumice, which play an important
part in the material obtained from great depths in the Atlantic ,
and Pacific oceans, the outline can scarcely be seen with an
object-glass of even moderate aperture, when they are mounted
in balsam, if the light use] for illumination be convergent, but
is seen to very great advantage when illuminated by the divergent
light obtained by using a concave lens instead of the usual convex
condenser, that is to say, following out the usual nomenclature,
when the aperture of the condenser has a negative value, or, so to
say, is considerably less than nothing. We are, however, limited
to low powers, by the light being made too feeble for high.

Object-giasses used.

The facts just described will make it very obvious that in study-
ing deposits there is no advantage in having object-glasses of large
aperture, but a positive disadvantage. When the light transmitted
is so convergent that the full aperture is utilized, the object becomes
almost, or quite, invisible from the absence of any dark outline,
and the focal point of such lenses being so near to their front
surface it is quite impossible to penetrate sufficiently deep down to
see the minute fluid cavities in the centre of grains of sand, or to
reach the fine particles lying on the surface of the glass slip, below
the thickness of balsam necessitated by the presence of large grains
of sand. For these researches Messrs. Beck have made for me a
1th of only 75° of aperture, constructed, however, with all possible
care, and I find it extremely useful, since I can easily reach all
parts of the object, and can obtain perfect definition with the power
of about 600 linear requisite to identify the extremely minute
fluid and glass cavities. I can also see the form of grains as small
as sy¢o00 Of an inch in diameter. Such cavities and particles are
excellent tests for those qualities in object-glasses necessary for the
present inquiry, since we know what we ought to see. Very few
objects occur less than those named, and even at that size we seem
to have arrived at the limit allowed to us in such cases by the pro-
perties of light itself. If this were not the case, we ought to see
a bright speck in the centre of the bubbles in the minutest fluid
cavities; but none can be seen when, calculating from the diameter
of the bubble, the central bright speck ought to be less than
evooo Of an inch in diameter. A 3th, with an aperture of 120°,

Anniversary Address of the President, H. C. Sorby, F.R.S. 119

does not enable us to exceed this limit, for reasons already
explained. The value of the larger aperture in studying an
entirely different kind of object is another question altogether.

On the Microscopical Character of Sands and Clays.

In studying loose and unconsolidated sands and clays little or
nothing can be learned respecting the structural arrangement of
the particles. Our attention must be almost entirely confined to
their mineral nature, external form, and internal structure. The
determination of some facts is certainly facilitated by our being
able to study detached particles ; but the observation of other facts
is made more difficult by our not being able to examine transverse
sections of the individual grains. In any case we are obliged to
make use of materially different methods of study, and must rely
on different classes of facts. I feel very strongly how imperfect
the whole subject still is. I have had great difficulty in obtaining
suitable material, since, as a rule, such specimens as are of the
greatest interest in connection with this investigation are seldom
collected, and I have been obliged to rely almost entirely on what I
collected for myself some years ago for this special purpose.

Origin of the Material.

In studying any particular stratified rock it would usually
much assist us in forming a true opinion respecting its formation,
if we could ascertain the previous history of the material of which
it is composed. Thus in the case of limestones it is desirable that
we should know the exact nature of the calcareous organisms,
which, by being broken up or decayed, yielded calcareous sands or
muds, since consolidated into hard rock. Very often this may to
a great extent be learned from the organic structure characteristic
of various groups of shells or corals. In some of our stratified
rocks we meet with larger or smaller fragments of previously
existing rocks, and even some of the oldest slates in Wales are seen
with the microscope to be, as it were, museums of specimens of the
rocks existing at the time of their deposition. The further study
of this branch of my subject may probably enable us to prove that
these ancient Welsh slates were in part derived from previously
existing strata, which were themselves derived from still earlier
rocks; but time will not allow of my entering into this question.
I purpose to limit myself to those facts which show the nature of
the rocks which, when decomposed and broken up, yielded the
detached grains of sand or other mineral particles subsequently de-
posited and consolidated. So very little attention has been paid to

120 Transactions of the Royal Microscopical Society.

this question that perhaps some geologists may be disposed to
doubt the possibility of determining it in a satisfactory manner ;
but, though we cannot learn all that we could wish, the form and
the internal structure of the individual grains of sand or finer par-
ticles of mud are often sufficiently characteristic to enable us to
draw several important conclusions. We may thus ascertain
whether the greater part of the deposit was derived from the
decomposition of slates, schists, or granitic rocks; and in the latter
case we may sometimes form a very satisfactory opinion respecting
the general characters of the parent granite. In order to show how
it is possible to learn these particulars, it will be necessary to
describe in detail the various characters of the principal minera.
constituents of the rocks now under consideration.

Quartz.—The grains of quartz, which are the chief constituent
of most sandstones, and occur in greater or less number in nearly
all shales and slates, have been derived principally from granitic or
schistose rocks, broken up by the action of currents of water, after
having been more or less decomposed by the action of the atmo-
sphere. The form and internal structure of those derived from
granite may be learned by studying thoroughly decomposed speci-
mens of that rock. By washing and sieving it is easy to separate
from the decomposed felspar the sand of coarser or finer grain,
which in addition to quartz contains mica, and more or less imper-
fectly decomposed felspar.

Quarta in Granite.—The form of the quartz grains is extremely
irregular ; but in most cases they are not much longer in any one
direction than in another, which is due to the structure of the
eranite itself being nearly the same in all directions. Usually the
grains are very angular, but some have such a rounded outline,
that, if their origin were not known, they might be supposed to
have been much worn by the action of water. The general
character will be better understood by referring to Plate CLXXIYV.,
which in Figs. 1 and 3 gives examples of the extreme types, and
in Fig. 2 a more common shape.

The irregular angular outline is due to the mutual interference of
the individual imperfectly grown crystals, which could not develop
true crystalline planes of any considerable extent. The effect of
this ‘interference of growth 1s, however, often visible as small sur-
face ridges, even when the general outline is scarcely at all angular ;
which thus proves that this exceptional rounded form is due to the
peculiar conditions of the growth, and not to mechanical wearing ;
since in that case all such surface irregularities would have been
removed. That each of these more or less irregular grains is a
single imperfectly developed crystal can be easily proved by means
of polarized light. When they are mounted in Canada balsam,

Anniversary Address of the President, H.C. Sorby, F.RS. 121

since its index of refraction is almost exactly the same as that of
quartz, light passes through them almost as though they were thin
flat sections, polished on both sides. Each grain then shows a
simple optical structure, and the colours round the circumference
are usually of low orders, which gradually or more suddenly rise to
higher orders towards the centre ; which proves that the grains are
not flat, but thickest in the centre, and more or less angular in
their outline, even in a plane parallel to the line of vision.

The internal microscopical structure is also easily seen when the
grains are mounted in Canada balsam, and there is no difficulty in
using sufficiently high powers. Amongst the more striking cha-
racters are the larger or smaller fluid cavities ; the hair-like crystals
of schorl ; and the extremely minute granules or crystals which can
scarcely be defined individually, but give rise to a general white
milkiness, when the illumination is of such a kind that they appear
white on a black background, and is to a great extent due to a vast
number of very minute bright specks, many of which are out of
focus. The chief variations in the character of different specimens
depend upon the size and amount of these various inclosures in
relation to one another and to the general mass of clear quartz;
but, as in the case of the granites themselves, these variations may
be sufficient to distinguish more or less completely those of par-
ticular districts, as, for example, the granites of Cornwall from
those of Norway or the Highlands of Scotland.

Quartz in Schists—I have not been able to detect any micro-
scopical character which enables us to distinguish between massive,
thick foliated gneiss and granite. There is a most perfect and
gradual passage from true and characteristic metamorphic schists
to typical granite, in the external form, internal structure, and
optical properties of all the constituent minerals. In certain dis-
tricts where the schistose rocks have undergone extreme meta-
morphism it thus appears probable that the granite has to some
extent been formed im situ, by the still further metamorphism
of the sedimentary rocks. There is, however, no difficulty
whatever in distinguishing between the less highly metamorphic
schists and granite, and more especially when the latter rock is
undoubtedly intrusive and no longer in the place where it was
formed. There is also a gradual passage from schistose to slaty
rocks which have undergone very little change since deposition.
It is therefore impossible to draw any absolute line of division
between rocks which on the whole have a very different struc-
ture, and have been formed under very different conditions, and
thus the only course open to us is to deduce general laws from
the study of characteristic specimens, fairly representing the
main masses of each particular class of rocks. This is more

122 Transactions of the Royal Microscopical Society.

especially desirable in connection with the subject now before us,
since in general the more doubtful passage beds would not have
a very great influence on the nature of the material derived from
the denudation of a large tract of country.

If, then, we compare the microscopical structure of granite with
that of a thin foliated mica-schist, cut perpendicular to the lamine,
we find that the difference is very great, independent of the more
or less complete absence of felspar. The schist is made up of flat
plates of mica, not as in granite lying in every possible plane, but
on the whole more or less closely parallel to one particular plane.
In the case of rocks having stratification-foliation this plane cor-
responds to the layer of different mineral character, and thus the
thin layers of quartz are often bounded on both sides by layers of
flat plates of mica. Hyen when the amount of this latter mineral
is not sufficient to constitute a continuous layer, the detached flakes
lie in one plane. The result of this is that the presence of so many
parallel flat plates of mica has to such a great extent interfered with
the growth of the crystals of quartz, that a very large proportion
of them are bounded by flat parallel planes of interference, and thus,
instead of having the extremely irregular form of those in granite,
they are on the whole characterized by having two surfaces
more or less flat and parallel. Fig. 4 will show the general cha-
racter of the transverse section of the forms thus produced, which
thus differ much from those derived from granite shown in Figs. 1,
2, and 3.

When detached and lying flat on glass, their characteristic
shape might easily be overlooked, but their flattened form is
revealed by using polarized light and an analyzer; since we
obtain comparatively uniform tints over their whole surface, instead
of tints rising rapidly from the margin towards the centre.

If the foliation be thin, much of the quartz may occur in such
flat plates ; but if the foliation of the rock be thick, more than one
crystalline particle may be and often is developed between the
layers of mica, and thus the grains of quartz may more or less
completely cease to be of a flattened shape. This is especially the
case if the schist possess cleavage-foliation, since then those grains
of quartz alone are flat which lie in the layers of mica. Those
that lie between the layers may be of an altogether irregular form,
and therefore, if the crystallization be coarse-grained, it might be
impossible to distinguish such quartz from that of some granites.
It is also impossible in the case of the quartz of the coarse-grained
quartzose layers of schists possessing stratification foliation. The
result of this is that even in sand derived exclusively from schists
a few grains of quartz may be expected to occur which could not
be distinguished from grains derived from granite.

Anniversary Address of the Presodent, H.C. Sorby, F.BR.S. 123

Though as far as mere form is concerned, the grains of quartz
in schist may thus sometimes be very similar to those in granite,
yet, on comparing the more common types of these rocks, there is
a well-marked difference in other respects. Usually the size of the
separate crystalline particles of the quartz in granite is much
larger than in the case of schists. Those in granite are also
usually bounded on most sides by felspar or mica, and thus, when
the rock is broken up by decomposition, each of the detached
quartz grains is, as it were, part of one single crystal, as already
named. On the contrary, those in schist being much smaller and
often bounded by similar crystals of quartz, firmly cohering to
them on all sides, when the rock is broken up there is only an
imperfect separation of the crystalline particles, and many of the
resulting grains of sand are of complex character. This dif-
ference can be detected by using polarized ight with an analyzer.
Thus, assuming that the general outline was the same in both
cases, in certain positions of the plane of polarization the grain
derived from granite would be uniformly dark or coloured over its
whole area, as shown by Fig. 5; whereas, if derived from schist, it
would present a tesselated appearance like Fig. 6, the detail varying
on rotating the plane of polarization. ‘The separate portions may
be in such perfect optical contact that this complex structure may
be quite invisible if polarized light be not used.

I have not been able to recognize any well-marked difference in
the ultimate microscopical structure of the quartz of granite and
schists. Minute needles of schorl are on the whole more common
in the quartz of granite, but they do also occur in that of many
schists. The quartz of some granites also contain a much greater
number of fluid cavities than that of most schists, but in the quartz
of other granites they are quite as rare as in the purest quartz of
any schists ; and thus the only safe conclusion is that the presence
of many needle-shaped crystals of schorl, or of many fluid cavities,
makes it more probable that the quartz was derived from granite
than from schists.

Mica, &e.—In comparing the mica from different specimens of
schists and granites, there is a similar difficulty in drawing any abso-
lute line as in the case of the quartz. The extremes are distinct
enough; but there is every connecting link in passing from mode-
rately altered to very much altered schists, to gneiss and to granite,
If it were possible to determine the true chemical and mineral cha-
racter of the mica in every case, even where two or more different
kinds are mixed together, much more could probably be learned ;
but in the practical study of the microscopical structure of stratified
rocks we are almost compelled to content ourselves with what can
be learned by means of the microscope alone, and to rely on general

124 Transactions of the Royal Microscopical Society.

facts, even though they are more or less affected by exceptional
differences. For this reason, in studying the micaceous con-
stituents, we are compelled to place far more reliance on mere
colour than would be admissible in accurate mineralogy ; but still
the difference of colour is often so well marked, that it does appear
to be characteristic, even although probably the same mineral
species may be thus separated and different species united together.
It must also be borne in mind that when I speak of mica I do so in
a very general sense for micaceous minerals, which may or may not
be true mica, and may often be more closely allied to chlorite. I
use it in fact in such a sense as is convenient for the purpose now
in hand. If we were to be content with nothing short of minera-
logical accuracy, it would be necessary to abandon the study in
despair. or this reason it is convenient to classify the micaceous
constituents as colourless, brown dichroic, and green dichroic.

The colourless varieties appear to occur both in granites and
schists, and no reliance can be placed in them to establish any
difference. On the whole, the dark brown-red or nearly black
dichroic varieties are characteristic of granites or very highly
altered schists, whereas the more or less green dichroic are charac-
teristic of less altered schists and slates.

Hornblende and Schorl.—The hornblende of schistose rocks
usually occurs in crystals considerably longer than broad, and
when broken up gives rise to fragments bounded by parallel sides,
with more or less rectangular ends, as shown by Fig. 7.

The colour is usually different shades of green, varying with
the position of the crystal, and showing blue-green and yellow-
ereen dichroism. Though sometimes occurring in granitic rocks,
hornblende is far more abundant as a constituent of schists in
those districts of England and Scotland which I have more par-
ticularly examined, and its presence in the associated stratified
rocks of more recent date must be regarded as indicating that they
were derived more from the decomposition of schists than of
granites.

Schorl not having a well-marked cleavage does not break up
into such regular shaped fragments as hornblende. The intense
dichroism of the coloured varieties is a most important character.
On the whole, it may be looked upon as more characteristic of
granitic than of schistose rocks, though it is probably in some
cases more abundant in the latter than is commonly supposed, and
thus no very definite conclusion can be drawn from the presence of
detached fragments in sandy deposits.

Felspars.—Except in a few cases where grains of the original
felspar sand can still be seen in mica schist, felspars are almost or
quite absent from this class of rocks. For the purposes of our pre-

Anniversary Address of the President, H.C. Sorby, F.R.S. 125

sent subject orthoclase may be looked upon as eminently character-
istic of granite and the associated gneiss, and labradorite of the
basic erupted rocks. When only very slightly decomposed, frag-
ments may usually be recognized by showing more or less distinct
evidence of a well-marked cleavage, like Fig. 8, or, in the case of
some species, by the compound banded structure seen with
polarized light and an analyzer, as shown by Fig. 9.

When very considerably decomposed, both these characters are
lost, and the fragments may be of irregular form, and show only a
very fine granular structure, appearing more or less dark and
opaque by transmitted light, and white with a more or less red
tint by reflected light. Fig. 10 is an example of such a fragment.
When completely decomposed, felspar easily breaks up into granules
of kaolin. These granules are usually very minute. From ;,; to
roooo Of an inch in diameter is a common size, but many occur
as small as soo0o- ‘Their refractive power is so nearly that of
Canada balsam as to make it difficult to distinguish them when
mounted in that substance, and they are seen to the greatest
advantage when examined in water. It requires some care to
clearly make out their form, but, as far as I have been able to
ascertain it by making them turn about, they are not, strictly
speaking, amorphous, nor yet minute crystals, but somewhat flat-
tened and elongated particles, very similar to those obtained on
reducing undecomposed felspar to a fine powder, as though the
original crystalline structure had had a very powerful influence in
determining the shape of the particles of the more or less pure
hydrous silicate of alumina produced by decomposition. As an
example of the shape of the particles, I refer to Fig. 11, which is
supposed to show an average example of a highly magnified
particle seen in various directions. There is, however, a consider-
able variation in the relative length, breadth, and thickness.

The depolarizing power of kaolin is high, and can be easily
recognized in particles as small as y2too of an inch in diameter.
Amongst the granules of decomposed felspar often occur small
needle-shaped crystals, the nature of which remains to be deter-
mined.

The glassy sanidin of modern volcanic rocks differs very much
from the felspars met with in granite ; but I must forbear to enter
at length into such volcanic products, since they have so little
direct bearing on British geology, to which I must chiefly confine
my remarks this evening.

Pumice.—For the same reason I need not say much respecting
pumice, although it plays such an important part in deep ocean
deposits. It has often no action on polarized light, being a true
felspathic glass, in the midst of which gas or steam has been given

126 Transactions of the Royal Microscopical Society.

off, so as to make it consist of little more than a mass of irregular
cells with thin dividing walls—a sort of glassy froth. As an
example of a fragment, I refer to Fig. 12, in which the shaded
parts represent the thin cell-walls seen edgewise.

Tron Oxides.—As a general rule the oxide of iron derived from
the decomposition of rocks is the hydrous peroxide. Sometimes the
separate granules can be recognized, but it often occurs as a mere
staining over the surface or in the interior of the larger fragments,
made up of granules too small to be separately defined. We thus
obtain various tints of red and yellow, made more or less brown by
the presence of the magnetic oxide. In some cases we also have
larger grains derived from crystals of this latter mineral which
were present in the original rock previous to its decomposition.
Changes taking place after deposition may soon alter the amount
of combined water, or give rise to ferrous compounds, or to pyrites,
and completely alter the colour of the rock, and may thus greatly
obscure the relation between modern and more ancient deposits.

General Conclusions.

Taking into consideration all the facts described above, I think
we are able to draw the following general conclusions. On the
whole, the particles derived from the decomposition and breaking up
of granitic rocks are sufficiently different from those derived from
schists to make it possible to decide to which of the more usual types
of those two classes of rocks they should be referred. When we
come to study individual particles, many may be found which show
the characteristic differences so very imperfectly that it may be
impossible to determine their origin in a satisfactory manner. In
examining any particular deposit, we must consider whether the
relative amount of such doubtful cases is greater than would
correspond with the amount of those clearly indicating that they
were derived from granite or from schists. Thus, for example, if
the great bulk of the material is like particles derived from schists,
the presence of a few grains of quartz which might have been
derived from granite may safely be attributed to the thicker folia
or quartzose aggregations in the schists ; whereas, if the great bulk
is made up of particles like those derived from granite, the pre-
sence of a few doubtful grains may be ascribed to exceptional
variations. We must, however, of course be prepared to find that
many stratified rocks have been formed from material derived from
both sources ; and, on the whole, the only safe conclusion is to say
that they have been mainly derived from one or the other, or from
both in some simple proportion, which can be only approximately
known.

Anniversary Address of the President, H. C. Sorby, F.RS. 127

In order to assist such determinations, it will be well to express
the necessary data in the following tabular form :

Granite. | Schists,
Larger grains .. .. | Some may show felspar | Some may show quartz
attached to the quartz. | enclosing plates of
mica lying parallel to
the external surfaces.
Quartz—
General form .. .. | More or less equiaxed .. | More or less flattened.
Optical structure .. Simple) 79.8) ) i) 2.0) Oftenicomplex:
Mica Spr) pdoselas a Hee Brown dichroic .. .. Green dichroic.
Felspar .. .. .. .. | Unaltered or decom- | Absent.
posed into kaolin. |
Hornblende .._ .. .. | Comparatively rare .. Comparatively abun-
dant.
Needles of schorl en- | Common.. .. .. .. | Much more rare.
closed in the quartz. |

Sorting of the Material.

In studying stratified rocks it is most essential to understand
the general laws concerned in the sorting of material suspended in
water, or drifted along the bottom by currents. When a grain of
sand or a flake of mica subsides in water, the accelerating force
of gravitation soon becomes equal to the resistance, and then the
particle subsides at an uniform rate, called its final velocity. The
actual amount of this final rate varies directly as the density of
the material, and inversely as the size of the grains; but the law is
made somewhat complicated by a variety of circumstances, amongst
which may be named the shape of the grains. In accordance
with this law very minute and perfectly detached particles subside
very slowly, and I find that the smallest granules of kaolin in
clay subside at the rate of about one foot in five days, whereas
grains of sand +35 of an inch in diameter subside a foot in about
ten seconds. If then there were nothing to interfere with this
law, the very fine particles of clay would seldom occur mixed
with grains of sand. Such a complete separation is, however,
very unusual, and as a general rule clays consist of particles of
extremely various size. ‘This can be easily explained by the very
peculiar physical characters of kaolin. When suspended in water,
the particles have a very great tendency to stick together and
collect into complex granules, somewhat like mist collects into
drops of rain, and in so doing may enclose grains of sand. The
rate of subsidence ig therefore not that of the separate indi-
vidual particles, but that of the complex granules, which is
tolerably uniform for all of them. It is much more rapid than
that of the separate minute particles would be, since, compared
with the surface, the weight of large particles is greater than that

VOL. XVII. Ti

128 Transactions of the Royal Microscopical Society.

of small; whilst at the same time the rate of subsidence is less
than that of the separate grains of sand would be, since the resist-
ance of the water is necessarily greater for such unconsolidated
granules.

This collecting together of compound granules depends very
much on the amount of material held in suspension, and also on
whether the water be quite still or agitated; and we can, I
think, thus easily explain why in some cases so much sand is
mixed with the clay, whilst in others the separation is far more
complete ; and can also explain the transport of material containing
fine sand over very wide oceanic areas, to places far removed from
the source of supply.

Practical Application of the above-described General Principles.

In studying loose deposits of sand or clay, whether in water or
in Canada balsam, we must bear in mind that the particles will
almost invariably rest with their flattest surfaces on the glass,
The result of this is that their flattened character might very
easily be overlooked. When examined in water much may be
learned by observing the effect of change of focus, and also by
making the grains turn round by slightly moving the covering
glass; but when mounted in balsam the difference is best shown by
the action of polarized hight, with an analyzer. If a grain of quartz
or any other doubly refracting mineral be thick and of irregular
form, the tints will rise rapidly and irregularly from the margin
towards the centre, whereas if it be flat there will be an almost
uniform tint over the whole surface.

Identification of the Constituent Minerals.

Quartz.—This may be best recognized by means of its irregular
outline and the absence of anything like cleavage planes ; by its
index of refraction being so nearly the same as that of Canada
balsam, that, when mounted in this substance, there is scarcely a
trace of shading round the exterior outline; and by the general
intensity of its action on polarized light. ‘This of course varies
with the inclination of the principal axis, but when in the ordinary
average position in which the grains are seen, those of moderately
uniform diameter in all directions give the following results :

Grains of s'¢ of an inch in diameter or upwards seldom show
bright colours except at the edges, the tint of the centres beimg
pale reds and greens.

Grains of about +}9 of an inch in diameter show the brightest
orders of colours.

Anniversary Address of the President, H. C. Sorby, FBS. 129

Grains yoloo Of an inch in diameter show only the pale bluish
white of the first order, or the complementary brown.

Calcite, &e.—Crystallized calcite may be at once distinguished
from quartz by the more or less conspicuous planes of cleavage.
This will not, however, apply in the case of fragments of calcareous
organic bodies. Since the index of refraction is considerably greater
than that of Canada balsam, their outlines are tolerably well marked,
when mounted in that substance. ‘he action of calcite and arragonite
on polarized light being so powerful, the bright orders of colours
are best seen when the fragments are about go'o> of an inch in
diameter, and when more than yoyo we usually obtain the faint
reds and greens of high orders or merely white light, distinguished
from the bluish white of the first order by not giving the comple-
mentary brown. When examined in water all doubt can be re-
moved by observing the action of dilute hydrochloric acid, which
dissolves calcite and arragonite with effervescence, and leaves quartz
and many other minerals unchanged.

Mica.—tThis is best recognized by its occurring as thin plates
haying a laminar structure. When in water or mounted in balsam
the flat surfaces lie parallel to the supporting glass, and it may be
somewhat difficult to appreciate their thickness and to distinguish
them from flat plates of quartz. If they cannot be made to turn
round, so that their edges may ‘be seen, the only course that can be
adopted is to illuminate carefully and observe the efiects of slight
changes in focal adjustment, which may suffice to prove that the
fragments are flat and have a laminar structure, with no cleavage
in any other direction. The occurrence of small granules or crystals
of red oxide of iron between the lamin may sometimes greatly
assist in forming a satisfactory conclusion, since a perfectly flat
thin layer of any such material is not at all likely to occur in
quartz. Advantage may also be taken of the difference in refractive
power, as described below when treating on glassy felspar.

Hornblende, &e.—What I have said when describing the horn-
blende and schorl in decomposed rocks will, I think, sufficiently
explain the methods I have employed in identifying them in
deposits. Perhaps the most decided difference between coloured
hornblende and schorl is the intense dichroism of the latter, so
that in certain positions no light passes through it.

Felspars.—As a general rule the difference between the felspars
in granitic and in volcanic rocks is so great that it may be con-
venient to consider them separately. Those in granitic rocks are
almost or quite free from cavities, or at most contains only a few
fluid cavities, whereas the glassy sanidin of volcanic rocks often con-
tains many well-marked glass cavities. It also differs greatly from
other felspars in various ways. Thus, whilst the orthoclase oj

L 2

130 Transactions of the Royal Microscopical Society.

granitic rocks shows with polarized light coloured bands due to
twin plates, and abite, oligoclase, and labradorite give more or less
well-marked evidence of their cleavage, the sanidin of modern
voleanic rocks often occurs as clear transparent fragments, having
a simple optical structure, and showing no more lines of cleavage
than a piece of glass.

On the whole, fragments of unaltered felspar constitute but a
very small part of our British stratified rocks, and glassy felspar is
probably almost or quite absent; but when we come to study the
modern deposits formed at great depths in the Atlantic and Pacific
oceans, we find that it plays a most important part. For some
time I feared that no ready means could be discovered to distinguish
between it and quartz. Both break up into irregular transparent
fragments, having a vitreous fracture, and, when of the same size,
give with polarized light the same tints, so that these minerals
cannot be distinguished by that means. At length, however, it
occurred to me that perhaps there might be sufficient difference in
their refractive power to cause them to appear different with
suitable illumination. As previously named, the refractive power of
quartz is almost absolutely the same as that of moderately fresh
Canada balsam, but I find that it is decidedly less than that of very
hard balsam. On the contrary, the refractive power of glassy
felspar is equal to that of this very hard balsam, and greater than
that of new and soft. Hence when both minerals are mounted in
soft balsam, transmitted light passes so evenly through the quartz
as to show little or no dark outline, whereas in passing through the
glassy felspar it is somewhat bent, and if the apertures of both the
condenser and object-glass are sufficiently small, the fragments
show a dark outline. The difference is, however, scarcely so well
marked as is desirable, and it is therefore better to make use of a
different illumination. By using a condenser with a central stop,
so as to get a black background, the oblique rays pass through the
quartz without there being any light reflected, and the outline is
invisible, or only shown by means of any superficial coating of some
other material which may be present. There is, however, seldom
any difficulty in distinguishing this from true surface reflexion.
On the contrary, the glassy felspar having a somewhat higher
refractive power than the soft balsam, reflects part of the light,
and causes the fragment to show a well-marked bright outline.
As far as I have been able to judge, this method gives satisfactory
results, which are confirmed by other facts. Thus, for example, on
examining some of the sandy matter washed from the deep ocean
clays brought back by the ‘ Challenger,’ I came to the conclusion
that certain particles were quartz and others glassy felspar, and
on examining these with a much higher power I saw that what

Anniversary Address of the President, H. C. Sorby, F.RS. 131

I had thus found to be quartz contained the usual fluid cavities,
with moving bubbles, whilst what I had concluded must be
felspar contained the well-marked glass cavities of modern volcanic
rocks.

There is little chance of confounding felspar and quartz in
studying British stratified rocks. The only fear is of mistaking
for one another fragments of decomposed felspar and portions of
stratified rocks formed of thoroughly decomposed felspar, consoli-
dated after deposition as separate granules.

Kaolin, &e.—The principal characters of this substance have
been already described. It may in general be identified by the more
or less elongated and flattened shape of the particles, and by its
strong depolarizing action, which, with crossed Nicols, suffices to
give a pale bluish white, even when the particles are p3}o5 of an
inch in diameter. There is no chance of confounding them with
minute particles of quartz, which to give such a tint must be about
four times that diameter. There is also no difficulty in distin-
guishing kaolin from decomposed or comminuted pumice and
some other analogous modern volcanic products, since the form of
these particles is very different, and they have little or no action on
polarized light. There is also no difficulty in distinguishing be-
tween true kaolin and the minute short needle-like crystals met
with abundantly in some decomposed volcanic rocks, since their
shape is so different.

Application of similar Principles to thin Sections of Rocks.

As an almost universal rule thin sections of stratified rocks
should be cut in a plane perpendicular to the stratification. In
this case the thin flat plates of quartz or mica are almost always
seen in transverse section, and the fact of their being thin and flat
is at once apparent. There is also little difficulty in distinguishing
between the thinnest pieces of quartz and the flakes of mica.
These latter are usually thinner and of more uniform thickness,
and with proper illumination and a sufficiently high magnifying
power the laminar structure of the mica may be easily seen. Its
colour and dichroism are also important characters, and observed to
the greatest advantage in transverse sections. The identification
of the various other minerals may be accomplished in the manner
already described, and the only point that needs special attention
is the recognition of the very minute granules of kaolin or micaceous
substances disseminated amongst the larger fragments, which may,
however, be accomplished by carefully regulating the aperture of
the condenser, which must be small.

132 Transactions of the Royal Microscopical Society.

Application of the above-described Principles to Special Cases.

The practical application of the general principles already
explained will, I think, be more readily understood if I describe a
few characteristic examples of various uatural deposits.

Millstone Grit of South Yorkshire.—It would be difficult to
find a better example of a coarse-grained sandstone, almost entirely
derived from granite, than the above-named rock. Some of the
beds can easily be broken up into loose sand, and the structure
of the grains observed when mounted in balsam. With very
few exceptions they are extremely angular, as shown by Fig. 13,
and in every respect identical with grains of quartz derived from
decomposed granite. Grains of unchanged felspar do sometimes
occur, but the greater part has been decomposed into clay, which
has been squeezed into the spaces between the grains of quartz.
In some few cases portions of felspar may still be seen adhering
to quartz, as shown by Fig. 14, which may therefore be said
to be actual grains of granite. The quartz is on the whole very
free from fluid cavities, and more like that from the granites of
Norway than from any British variety which 1 have examined,
and certainly very unlike that from the Cornish granites. These
conclusions agree admirably with other facts. In the associated
pebble beds portions of undoubted granite may be found. It is
of coarse grain, with comparatively clear felspar, quite unlike the
usual varieties met with in Scotland or Cornwall, but closely like
those from Norway. ‘The current structures of the rock clearly
show that the material was drifted from the north-east, and it was
probably derived from granitic rocks lying at no great distance in
that direction. Even the much finer grained quartzose sand beds,
like the gaunister, have apparently been mainly derived from
granitic rocks. We need not go far.to find the other constituents
of the granite. Mica abounds in some beds, and the decomposed
felspar has no doubt largely contributed to the material of the
associated shales and indurated clays. Nearly all the grains of
quartz are as angular as if never subjected to attrition ; but a few
are so much worn that they may have had a different history—
they may have been exposed longer to wear, or may have been de-
rived from dunes of blown sands.

Sand of the Egyptian Desert,—This is a splendid example
of a sand which has been very much worn by attrition, as shown
by Fig. 15, all angles being removed. Ordinary dune sand shows
the same kind of wearing in a less degree. When blown about
by the wind the friction of the grains one on another is necessarily
much greater than when they are to a considerable extent buoyed
up in water, and there is thus no difficulty in understanding

Anniversary Address of the President, H. C. Sorby, F. B.S. 138

why so many have been far more worn and rounded than the
grains met with in subaqueous deposits. Both in them and the
sand of the Desert, other things being equal, the amount of
wearing is greater in the case of the larger than in the case of the
smaller grains, which is easily explained, since their weight and
the amount of friction would necessarily increase in higher pro-
portion than their diameters. The contrast between this sand of
the Desert and equally coarse sand from the Millstone Grit is most
striking, as will be seen on comparing Figs. 13 and 15, and points
most clearly to a very different history, although the materiak
was in both cases originally derived from granite.

Sand derived from Schists—On the sides of the valley of
the Tay, north of Dunkeld, occur terraces of sand at some eleva-
tion above the river. This sand is fine-grained, the common
size of the grains being about st> of an inch. ‘There is no
difficulty whatever in seeing that a very large proportion are
flat plates, either by making them turn round in water, by care-
fully studying their appearance when the focus is slightly changed,
or by examining their action on polarized light, when mounted
in balsam. Fragments of dark green hornblende are common.
Since we cannot examine sections of the mica in the proper
direction, its dichroism cannot be observed, but some of the
darker flakes may have been derived from granitic rocks or
highly altered schists. On the whole, the microscopical characters
clearly indicate that the great bulk of the deposit was derived
from schists; and, considering the geological character of the
surrounding country, there can be little doubt about the accuracy
of this conclusion.

In the neighbourhood of Moffat and of Bangor occur hard slate
rocks without cleavage, which can easily be cut into thin sections
perpendicular to stratification. These show alternating layers of
coarser and finer grain, and of red or pale green colour. The
erains of quartz sand in the coarser layers are seldom y}5 of an
inch in diameter. Those of 335 to s}y are common, and many
are yoyo or less. A large proportion of these are flat plates, like
those derived from schists, and in some cases they enclose plates
of mica parallel to their longer axis, as shown by Fig. 16,
the shaded part being the mica. Such a grain may be looked
upon as a fragment of mica schist. The quartz is usually
broken up into such small fragments that only a few show
complex structure. Well-marked grains of green hornblende
occur, and a good deal of green dichroic mica. ‘There are,
however, a few which are dark dichroic, and in the very fine-
grained layers are many minute granules, having all the characters
of those derived from felspar or other minerals of granite rocks

134 Transactions of the Royal Microscopical Society.

which decompose into similar material. Taking all these facts
into consideration, there can be no reasonable doubt that a very
large portion of these rocks has been derived from schists, which
has been deposited along with a little mica and many very fine
granules, derived from perhaps more distant granitic rocks.

lt appears to me scarcely necessary to describe any other
special cases. As far as I have been able to ascertain from an
examination of sandy deposits belonging to nearly every period of
our British stratified rocks, I think we may conclude that, as a
general rule, the coarser-grained sands are mainly derived from
granitic, and the finer from schistose rocks; which is no doubt
because the separate solid fragments of quartz in granite are
usually much larger than those in schists. Even the oldest slates
which I have examined thus furnish evidence of the existence of
still earlier strata, subsequently metamorphosed. One thing which
may appear somewhat surprising is that on the whole the grains of
sand are very little worn, and hence the finer-grained sands have
not resulted from the wearing down of larger grains, but consist of
particles which were originally small, separated from the larger by
the action of currents. That part of the quartz worn off from the
rounded grains is probably met with in the clays mixed with
the true kaolin. It seems scarcely possible that the larger solid
grains could be reduced to smaller by simple fracture, by the action
of currents.

The microscopical structure of the quartz enables us to form
some idea of the general character of the granitic rocks which have
yielded so large a part of the coarser sands met with in British
strata. They must certainly have been very unlike the Cornish
granites, since the quartz of these latter contains a far greater
number of fluid cavities. They must have been much more like the
granites of the Scotch Highlands or those of Norway, and perhaps
we should not be far wrong if we were to conclude that they be-
longed to a type intermediate between these, which formerly
occurred in an area now no longer dry land.

The difference in the colour of different sands depends on the
amount and condition of the oxide of iron, forming as it were a
superficial varnish. This is easily seen when the grains are
mounted in balsam. ‘The quartz itself is the same, and since the
state of the oxide might be so soon changed, there is no difficulty
in understanding why sands of such very different colours may be
associated together.

The green grains of glauconite cannot as a general rule have
been derived from pre-existing rocks, and ought rather to be
attributed to chemical action occurring either during or soon after
deposition, like the minute crystals of gypsum met with in some of
the dredgings from the Pacific Ocean.

Anniversary Address of the President, H. C. Sorby, F.R.S. 135

Clays, &e.—The chief portion of the fine-grained clays cannot
be distinguished from the products of the decomposition of felspars
and other minerals which can be changed in a similar manner;
but mixed with this is a very variable amount of fine sand, in
all probability transported in the compound granules already de-
scribed. Since the sorting of the material depends upon its
amount, and on the conditions of the current, there seems reason
to hope that a further study of the ultimate character of clays
may throw much light on these questions. Some of these indicate
that they were rapidly deposited from very muddy, shallow water,
and others that they were deposited from much clearer and deeper
water.

Volcanie Ash Beds in British Strata.—Extensive masses of
rock have been often described as ash beds, but, when we come to
examine the detailed structure, their true nature becomes very
doubtful. Some of them may really have been true ashes, but
they have undergone so much subsequent change that they are
now totally unlike the ashes of modern volcanoes. The whole
question requires much more examination, and the study of the
subsequent alterations becomes the principal consideration, and
it would lead me into far too wide a field of inquiry to enter
upon it now. ‘That true but much altered ashes do exist is,
however, clearly shown by some beds found at Bathgate, near
Linlithgow. These show a structure which seems to indicate
that they were originally a pumice ash, but the vesicles have
been filled with infiltered mineral matter, and the whole greatly
altered by chemical changes taking place after deposition.

Conclusion.

Leaving then out of consideration such cases, and confining our
attention to by far the greater bulk of our British non-calcareous
stratified rocks, we see that a most careful microscopical investiga-
tion shows that the material was originally derived mainly from the
chemical decomposition and mechanical breaking up of various
granitic and schistose rocks, the products having been afterwards
separated and sorted by the action of currents, and more or less con-
solidated and changed by subsequent mechanical and chemical action.
When we come to study the detail, it is also possible to form a satis-
factory conclusion respecting the share which each of the above-
named classes of rocks contributed to the formation of each particular
stratum, and also to answer several questions of great interest in
connection with the geological history of a very important group of
stratified rocks, which hitherto have not been supposed capable
of yielding any such information. Though these conclusions are

136 Transactions of the Royal Microscopical Society.

in perfect harmony with well-known geological facts of an entirely
independent character, yet some at least could not have been
established in a satisfactory manner without tasking the utmost
powers of the microscope, which are often required to see and
identify the extremely small or larger particles of which the rocks
are composed.

EXPLANATION OF PLATE CLXXIV.

Fics. 1, 2, 3—Grains of quartz from decomposed granite.
Fic. 4.—Grain of quartz from schist.
Fies. 5, 6.—Grains showing the contrast between simple and complex structure
when seen with polarized light.
Fic. 7.—Fragment of hornblende.
» 8.—Fragment of felspar.
,, 9—Fragment of felspar seen with polarized light.
, 10.—Fragment of decomposed felspar.
,, 11.—Granule of kaolin in various positions, very highly magnified.
,, 12.—Fragment of pumice.
,, 13.—Grain of quartz sand from Millstone Grit.
, 14.—Fragment of granite from the Millstone Grit.
,, 15.—Grain of sand from the Desert.
,, 16.—Fragment of mica schist from the slate rocks near Moffat.

GoLeia)

Il.—Measurements of Rulings on Glass.

By Evwarp W. Mortey, Western Reserve College,
Hudson, Ohio, U.S.A.

Puate CLXXV.

In November 1875, Mr. Rogers, while employed in perfecting the
details of his engine for ruling lines on glass, asked me to measure
the intervals between the lines on a plate which he ruled for the
purpose and sent to me. It contained a hundred heavy lines ruled
twenty-four hundred to the inch, forty heavy lines ruled four
hundred and eighty to the inch, forty light lines ruled like the last,
ten lines ruled twenty-four to the inch, and a hundred light lines
ruled twenty-four hundred to the inch. My attention was given
to the detecting and measuring any periodic errors occasioned by
periodic errors in the screw of the ruling engine, by eccentricity of
the screw head, and by other causes producing similar results. To
determine this kind of inequality with the smallest probable error,
it was obviously proper to measure, not intervals produced by a
hundredth of a revolution of the screw, but intervals ten or twenty
times as large. ‘Twenty-three intervals of the hundred and twen-
tieth of an inch as nearly consecutive as possible were therefore
measured. After several preliminary trials with objectives of foci
ranging from two inches to the sixteenth of an inch, a nominal
inch objective, whose focal length is really eight-tenths of an inch,
was selected for the work. It had been found that the same care
with this objective gave results with a less probable error than any
other tried. Mr. Rogers afterwards suggested that even a quarter-
inch objective was too low a power to afford the required accuracy.
While I cannot undertake to say what instrumental appliances are
best suited to the habits, methods, and predilections of another ob-
server, the fact remains that for myself the work in hand could be
done with this objective so that a given amount of care made the
probable error of results less than when the work was done with
either a half, quarter, eighth, or sixteenth. The fine adjustment
of the stand was screwed hard down and left untouched throughout
the measurements. ‘The micrometer employed was a cobweb mi-
crometer by Troughton, having two movable wires. The screw
heads have each a hundred divisions; the fourth part of a division
was read by estimation. Two readings were taken for each interval
measured, between which the screw heads were both moved several
divisions. ‘The wires were brought to the edges of the images of
the lines of the glass plate, till the minimum visible bright line
between the image and the wire was the same for each wire. As
each interval was measured only twice, one can hardly compute the

0 Ee ee

=

, s

=—

138 Measurements of Rulings on Glass. By E. W. Morley.

Upper Curve: Upper Curve: Lower Curve: Lower Curve:
Abscisse. Ordinates. Abscisse. Ordinates.
Millim. Millim. | Millim. Millim.

0 — 4:2 0 + 0:8

5 + 5:1 6 +08
10 + 2:4 | 12 — 12
15 — 6°7 18 + 1:4
20 — 1:0 24 — 14
25 — 0°3 30 + 0°2
30 + 8°6 36 — 0°2
35 + 0°8 | 42 a
40 - 6:1 | 48 — 07
473 — 78 | 54 + 2°0
523 413 | 60 ah,
574 + 3°6 66 — 0°3
623 — 5°8 72 — 1-2
673 — 4:2 78 + 0'7
764 + 4:1 84 — 1:7
814 + 5:1 90 + 1:4
864 + 0:5 96 — 07
912 — 4:7 102 + 0:2
964 + 1:2
1014 + 5:8 |
1062 + 5°4 |
1112 + 0:3 |
1164 — 4:1

Horizontal scale, 10 millim. = ;}, inch.

Vertical scale, 10 millim. = z5355 inch.

Monthly Microscopical Journal, March 1, 1877. PLATE CLXXV.

WACK
VA
oe

3/100,000 77,

Y/10,000 tn.

i)
B)

Luilinitiuitui! fila

Measurements of Rulings on Glass. By E.W. Morley. 141

probable error of a mean. But the probable difference of the two
measurements of one and the same interval will afford a convenient
and, for the purpose, sufficient means of estimating the degree of
confidence which may be felt in the result. The differences between
two measurements of the same interval were one-fourth of a diyi-
sion in seven cases, two-fourths in five cases, three-fourths in three
cases, one division in two cases, one division and one-fourth in four
cases, and one division and two-fourths in two cases. From this it
appears that the probable difference of the two measurements of the
same interval is fifty-six hundredths of a division of the screw head.
Now the value of one revolution of the screw in the given circum-
stances was the fourteen hundred and seventy-sixth of an inch, or
0-0006775. Hence the probable difference of two measurements
for the same interval was the two hundred and sixty-one thousandth
of an inch. It will be seen that this degree of accuracy was amply
sufficient for the purpose. It will be noticed that twelve of the
actual differences were smaller than the probable difference, and
eleven were larger.

In Figure a, Plate CLXXV., the measurements are plotted by
making the abscissze proportional to the distance of the initial line
of each measurement from the line where the measurements began,
while the ordinates are proportional to the differences between the
successive measurements and a constant subtrahend. It will be
seen that an error whose period is five times the measured interval
is clearly indicated.

If the shortest interval of each of these five cycles is subtracted
from the longest, the differences are successively seventy, eighty-
six, fifty-five, fifty-eight, and fifty-eight: the unit being the four
hundredth part of the revolution of the micrometer screw. Half
of the mean of these differences is that part of the periodic error
which corresponds to the fifth part of the circumference of the screw
of the ruling engine, or to an are of seventy-two degrees. This
quantity is eight and seventeen hundredths divisions of the screw
head of the micrometer. If this be multiplied by the ratio of the
diameter of the circle to the chord of the arc or seventy-two degrees,
we have a tolerable approximation to the whole periodic error of
those threads of the screw which produced these lines, as the screw
was at the time adjusted. This quantity is the ten thousand six
hundredth of an inch, or 0000094 inch. This quantity represents
the greatest possible displacement of a line from its true place, as
far as the displacement is periodic and not accidental; the greatest
possible difference between two professedly equal intervals is double
this quantity. '

If doubt is felt as to the propriety of assuming that the errors
for a fifth ofa revolution and for a half revolution are proportional
to the chords of the ares, the total displacement of a line by periodic

142 Measurements of Rulings on Glass. By EH. W. Morley.

error may be computed in another way. If we subtract the mean
of the whole twenty-three measurements from the successive mea-
surements, we get the following column of residuals. If now we
add all the successive residuals which have the same sign, we get
the total measured displacement of the last line before the change
of sign. In this way we obtain the column of displacements.

ate Mean. Residuals. Displacements,
12,237 12,299 =) (92
12,375 a ae. ae
12,335 . + 36 i se os
12,200 _ Log
12,285 ” - U4 — 117
12,295 e He
12 425 ” + 126 |
12,312 f ti. i} +389
12,210 ~ merce)
12,185 < = ANd i = ae
12,320 99 + .21 |
12,352 m1 Eee: \ + 74
12,215 Pa me |
12.237 | ee
12,360 a5 + 61 |
12,375 + + 76 |$ +4 145
12,307 if 4a
12,230 % =; S| dae
12,317 a BY ati | hm
12,385 » + 86 |

| 12,880 z + 8i + 191
12,305 | - eer
12,240 » — 59 | — 121

aT

The mean displacement, without regard to sign, is thirteen
divisions and two-tenths ; this quantity is the eleven thousand two
hundredth of an inch, or 0°000089 inch. This quantity is twenty-
four times as large as the probable difference of two measurements
of the same interval. It is identical with the previous value.
This agreement shows that the error is proportional to the chord
of the arc of the screw which corresponds to the measured
interval. It may be said that since the measured intervals were
not all absolutely consecutive, the first method probably is the
more accurate.

Mr. Rogers, who did not for a time admit the conclusiveness
of the foregoing measurements, thought that the periodicity shown
in my results was most probably due to periodicity in the micro-
meter screw employed. But it is obviously impossible to suppose
that to such a cause could be due inequalities amounting to a fifth
part of its pitch. And further, the measurements were so made
that the effect of periodic errors in the micrometer could per-

Measurements of Rulings on Glass. By EH. W. Morley. 1438

ceptibly affect only the accuracy of the reduction of the differences
to fractions of an inch, while such errors could not affect the relative
magnitudes of these differences except by quantities which may be
neglected.

A plate ruled by Mr. Rutherford, of New York, was afterwards
measured in the same way, but with less care in making contacts.
Kighteen intervals were measured ; the differences of the two mea-
surements of the same interval were nothing in two cases, one in
five cases, two in three cases, three in three cases, four in one case,
seven in one case, and eight in three cases; the unit is the four
hundredth of a revolution of the screw head. The probable differ-
ence of the two measurements of the same interval is sixty-seven
hundredths of a division. If the measurements be plotted, as in the
former case, the result is seen in Figure b. If the shorter interval
in each cycle is subtracted from the longer, half the mean of these
remainders is the greatest observed displacement of a line by
periodic error. This quantity is the seventy-six thousandth of an
inch. This is but four and one-half times as large as the probable
difference of the two measures of the same interval. The measure-
ments therefore cannot be used to give the amount of periodic error
in Mr. Rutherford’s screw, while they conclusively show that it is
much smaller than in the former case-—Lead before the American
Association for the Advancement of Science, August 1876,

VOL. XVII. M

(1444)

NEW BOOKS, WITH SHORT NOTICES.

The Microscope and its Application.*—The appearance of a second
edition of Professors Nigeli and Schwendener’s Handbook of the
Microscope (on the merits of which there is but one opinion abroad)
will be hailed with interest by many in thi& country. Nor will this
interest be diminished by the circumstance that the text-books
which respectively represent foreign and English micrography differ
so widely in subject, plan, and treatment. Our English manuals
scarcely enter. upon that optical ground which is supposed to be
specially reserved for the practical optician, whose authority as the
designer and constructor of microscope combinations is accepted
without question. On the other hand, they give full play to the
fancy which dictates preferences for variety in size, shape, and
mechanical arrangement of the instrument; in which respects the
only gujding principle of any value—namely, that the instrument
should be as little as possible encumbered with mechanical appliances,
and that as much as possible should be left to the skilled manipu-
lation of the observer—is too often neglected. But the English
manual is chiefly distinguished by its fullness of detailed directions
“how to work with the microscope,” and naturally blends with these
directions a great amount of information regarding the various sub-
jects of microscopic research as well as their technical manipulation.
And thus it happens that the most important chapters of the English
treatise are not those in which the optical construction of the micro-
scope is explained, but rather such as treat of “its revelations.”

But in the foreign handbooks, treating professedly of the theory
and construction of the microscope, no place is made for disquisitions
upon subjects of natural history, histology, or the special sciences of
anatomy, pathology, &e. Firstly, because the theory of the micro-
scope is treated in Germany as a physico-mathematical problem, in
the demonstration of which the physicist and mathematician have
equal if not superior rank with the mechanical constructor. And
secondly, because the establishment of various schools of microscopy
in the several university towns, and the issue of various scientific
journals by professors connected therewith, as well as the frequent
publication of special monographs, render every facility for micro-
graphic literature, without trenching upon the volume specially
devoted to the theory of the microscope and its manipulation.

In the present phase of microscopic science another motive to
study of the optical conditions under which appearances seen through
the microscope must be interpreted, comes strongly into play: a
motive which ought to be felt equally by all who profess to look
a step or two beyond the mere amusement found in observing toy

* ‘Tas Mikroscop: Theorie und:Anwendung desselben,’ von Carl Nageli, Pro-
fessor in Miinchen, und 8S. Schwendener, Professor in Basel. Zweite verbesserte
Auflage, mit 302 Holzschnitten, Leipzig: Verlag von Wilhelm Engelmann.
1877.

NEW BOOKS, WITH SHORT NOTICES. 145

objects. For the surprising diversity—not to say antagonism—of
view entertained by different observers who have over and over again
examined the same object and yet have interpreted so differently the
appearances observed, could not but lead to the conclusion that the
microscopic image itself is not always the same unaltered transcript
of the same light and shadow picture. The more difficult therefore
the problem placed before the microscope for solution, the more
needful should it seem that the theory of the compound microscope
.be again strictly revised, if the difficulties of interpretation which
increase with every fresh strain put upon the instrument are to be
overcome. By Teutonic minds the relegation of so congenial a labour
into the hands of the optician was not likely to be tolerated ! and as
little would they be content that such knowledge should lie outside
the recognized sphere of scientific investigation.

The physico-mathematical investigation of the theory of the micro-
scope has thus naturally fallen into the hands of those for whom this
subject possessed special attraction. But it may also be fairly expected
that all who are interested in microscopic research generally, should
desire to hear of any new discovery that might come to light, or of
any fresh aspect in which what was already known might appear after
renewed examination. A second edition of a well-accredited work has
therefore real significance, and appears opportunely for the lovers of
microscopic science at a period when the limit of the powers of the
microscope seems to have been reached, and, in default of adequate
explanation and rational guidance, a certain misdirection of energy in
any further efforts to add to its powers becomes imminent.

The work of Professors Nigeli and Schwendener, of which we
here propose to give a short account, brings down to the end of the
year 1875 the latest summary of the optical questions connected with
the theory of the microscope and of the conditions under which the
various objects submitted to microscopic analysis are seen. <A glance
at the table of contents will best show the German method of handling
a rather complicated theme, and the space occupied by each section
will roughly indicate the relative importance of each.

Section 1.—103 pages are devoted to the theory of the microscope
and the demonstration of optical problems therewith connected.

Section 2.—6 pages containing remarks and recommendations
relating to mechanical arrangements, with 15 pages of description
and woodcut illustration of foreign stands of various makers.

_ Section 3.—60 pages occupied with discussion of modes of pro-
cedure for testing the accuracy of optical construction and the relative
values of lens combinations.

Section 4.—50 pages. The theory of microscopic vision, including
the phenomena of “interference”; the effect of illumination upon
various objects seen by transmitted light direct and oblique; and the
effects produced by objects in motion, and by changes of level (in
focussing different planes).

Section 5.—15 pages on the simple micr sroscope.

Section 6.—35 pages on technical manipulation.

Section 7,—62 pages on phenomena of polarization.

Mw 2

146 NEW BOOKS, WITH SHORT NOTICES.

Section 8.—104 pages on micro-physics.

Section 9.—62 pages on micro-chemistry.

Section 10.—113 pages on the morphology of vegetable or-
ganisms.

The purely technical character of this handbook will be at once
inferred from the brief abstract of contents here given. For even in
the concluding chapter on vegetable morphology the physico-mathe-
matical method is as equally predominant as in the rest of the work.
It is not possible to convey by any condensation or analysis an
adequate idea of the profound research and practical knowledge
displayed by the authors in their treatment of the several sections ;
but it may interest our readers if we touch upon a few points which
are either new to the majority of English microscopists, or on which
the judgment of competent experts, whose opinion derives weight
from their special experience, is opposed to the general belief and
practice in this country.

1. Binocular microscopes do not find favour in Germany. A
stereoscopic arrangement must of course produce the same appearance
of solid dimensions of objects which other instruments of the kind
effect ; but whether, say our authors, any aid is thereby afforded to
scientific observation — for example, whether the discrimination of
actual differences of form and density is thus facilitated—we must take
leave to doubt.

The authors’ explanation of the stereoscopic effect, so far as it
depends upon physical grounds, is as follows. Each of the two pic-
tures formed by the two halves of the objective shows an altered
distribution of light and shadow as compared with the light and shade
of the picture ordinarily transmitted through the whole area of the
objective, the shadow prevailing on the side of the excluded half area,
so that a shift of light and shade in opposite directions in the two
pictures is effected. Which of the two sides is presented to the right
or left eye depends on the particular arrangement of prisms, but this
makes no difference in the causation of the stereoscopic effect.

How far the depth of field (apparent difference of level of different
points of the objective image) modifies the stereoscopic effect is again
matter of contention; no one doubts that a certain depth exists, but it
is certain that its influence in completing the stereoscopic effect is
unimportant, and by no means necessary. For just as the superficial
photograph impressions on the ordinary stereoscopic slide unite in a
picture giving perspective effects, so must the images of the binocular
cause an impression of corporeality, even if there were no depth of
field. Helmholtz explains* the production of stereoscopic effect by
referring to the position of the dispersion circles caused by points in
the object lying in front of or behind the focal plane of the objective
image: that is to say, that depth of field is an essential condition of
stereoscopic effect. But our authors object that, independently of
this supposed action of dispersion circles, the pictures formed by the
two half areas of the objective are already differentiated by altered
distribution of light and shade, and therefore of themselves bring the

* ©Handbook of Phys. Optik.’

NEW BOOKS, WITH SHORT NOTICES. 147

stereoscopic effect to pass. And, finally, say our authors, “ We must
call attention to a fact that seems hitherto to have been overlooked.
The idea of projections and depressions may be caused by mere dif-
ferences of density, which, when an object is examined by transmitted
light, must produce exactly the same optical effect. If we suppose a
membrane equally thick throughout, but containing in its substance
parts of greater and less density, the denser spots will appear in the
stereoscopic picture convex, and the less dense spots concave, and
so produce an illusory effect on the senses. For this reason we con-
sider it more prudent, under present circumstances, to prosecute
scientific researches with the ordinary monocular instrument.”

2. We pass on now to another subject of general interest, upon
which our authors have expressed a decided opinion, namely, the
significance of aperture of objectives.

Referring to the distinction originally made by Herschel in the
case of the telescope between defining and penetrating power as one
which applies equally to all optical instruments, not excepting the eye
itself, our authors say, “ Let it not be forgotten that penetrating
power rises or falls not with the aperture of the refracting lens, but
with the aperture of the cones of light which proceed from the object
to the lens. It is self-evident that when incident pencils of light
occupy only a part of the aperture of an objective the whole of the
unoccupied portion is inactive.” When, however, a parallel is drawn
(as has been done by Goring and others) between penetrating power
as understood in the telescope, and that which is termed penetrating
power in the case of the microscope, it becomes necessary to examine
in what sense this transference of idea is to be explained. Now in the
telescope its entire aperture is occupied by beams of light which come
from the object seen (as if they were self-luminous), and an increase of
its aperture (just as the widening of the pupil of the eye) has only one
purpose, namely, increase of light when the objects to be seen are
weakly illuminated. If this light be too strong, wide aperture exer-
cises only a disturbing influence, as lenses of wide aperture are mostly
affected with serious aberration. But, say our authors, the illumination
can be intensified at will in the case of the microscope (up to applica-
tion of direct sunlight), so that the need of large aperture for illu-
mination does not come into consideration. Further, it is well known
that the cones of light admitted through the diaphragm openings are
so small that the rays converging on the focal plane form cones which
have not commonly a greater aperture than 23°-30°, and these, after
undergoing a change of course in the objective, again group them-
selves into cones which appear as if they severally came from separate
points of the object to form an image of that object in the microscope.
The apertures of these pencils are approximatively the same as those
of the incident pencils. Supposing therefore an objective to have
60° to 80° of aperture, the separate pencils only partly occupy this
aperture, so that the sense in which penetrating power has been used
as a term applicable to the telescope (i.e. the power of penetrating
space gained by additional admission of light) is altogether mis-
applied in the microscope. The large object-glass of the telescope

148 NEW BOOKS, WITH SHORT NOTICES.

collects light from a distance, but the resolving of distant points of
light (as double stars) is more dependent upon the freedom of lenses
from aberration than upon their size, and thus in the microscope
likewise the capacity to “bring out” lines, points, and minute details
of structure must be associated with similar resolving power of the
telescope, not with its “ penetration.” *

In seeking to determine the significance of aperture our authors
show that the dioptric function of the lens depends just as much upon
the aperture of pencils incident from the object (this being itself
governed by the size of the openings in the diaphragm or screen
which marks the boundary of the illuminating cones) as upon its own
aperture, and that it is theoretically unimportant whether with an
objective of 60° aperture a diaphragm opening giving 30° aperture
of incident pencil is used, or vice versd, so that the advantage of wide-
angled aperture does not relate to the image-forming function, except
in so far as middle and peripheral zones of a wide-angled lens offer
the possibility of a correction of aberrations which shall affect each
area separately, and therefore the optician may make the peripheral
zone work well with oblique illumination, leaving the central zone
less perfect. The authors fully accept Professor Abbe’s demon-
stration, that the value of aperture consists in the admission of the
diffraction pencils which arise in objects containing details minute
enough to cause diffraction of the illuminating pencils, and that all
minute structure can only be transmitted as interference images by
pencils which a small-angled objective cannot take in. The following
extract contains an expression of opinion respecting this particular
item of Professor Abbe’s work, which, coming from experts ranking
amongst the highest authorities on a subject which they have made
their own, is honourable to themselves while giving the place of
honour to another.

“ It may not be superfluous to note here with emphasis, that up to
the present time the precise effect of aperture has not been established
as a scientific fact in any work on micrography known to us, much
less has it been explained. Nor do we find in the experiments de-
scribed by Harting (the second edition of whose treatise has but
lately appeared) any decisive result beyond the proof that in a given
case (experiment with two microscopes) the peripheral zone of the
object determined the issue. Indeed, from the time of Goring up to
our own day the whole question of aperture and its effect has been
altogether devoid of any satisfactory and sound basis. It is the great
merit of Abbe that he has filled up the void by a clear and well-
grounded exposition.”

In concluding this notice of Professors Nageli and Schwendener’s
Handbook we must remark that the chapters 3 3, 4, 7, 8, 9, and 10
are worthy of the closest attention. 'The last chapter i in particular i 1s

* The same conclusion is arrived at by Helmholtz, and the whole subject of
delineation of the objective image by pencils of light whose aperture is regulated
by diaphragm openings is fully demonstrated in the essay ‘On the Optical
Capacity of the Microscope, a translation of which appeared recently in the
‘M.M.J.’

PROGRESS OF MICROSCOPICAL SCIENCE. 149

specially worthy of study, the exposition of vegetable morphology
therein given being such as only the expert botanist, who is at the
same time deeply versed in physical science and minute anatomy,
could have written. The whole work is a mine whose treasures
might occupy many workers in developing.

PROGRESS OF MICROSCOPICAL SCIENCE.

The Structure of Centropyxis.—Professor Leidy, of U.S.A., who has
been publishing a series of papers on the structure of Rhizopods and
their cogeners before the Academy of Sciences of Philadelphia, gives
the following description of this interesting genus :—“ Centropyxis is
a nearly allied generic form to Arcella, and is so polymorphous that I
have been puzzled to define varieties. The test or basis of the test is
membranous, and appears not to exhibit the hexagonal structural
elements of that of Arcella. The shape is a modification of that of the
latter; the mouth and the summit of the dome being eccentric in
opposite directions. The dome varies in degree of prominence, and is
always convex. The mouth varies in proportionate size, and is more
frequently sinuous at the border than completely circular. The test
presents all the variations of colour presented by Arcella vulgaris. It
is frequently provided with from two to five or more hollow, conical
spines diverging from the wider border or that most distant from the
mouth. Sometimes the test is clean or devoid of all adherent matters
and appears homogeneous; mostly, however, it is more or less covered
with mineral particles. Sometimes it is as completely covered with
quartzose particles as an ordinary Difflugia, and frequently it is loaded
with larger stones along the deeper border. In some specimens the
test appears to be wholly composed of a single species of diatom
shells. I have observed a peculiar point of structure in most tests of
Centropyxis, which appears heretofore to have escaped notice. From
the sinuous border of the mouth a number of processes extend upward
to the dome. These are expanded at the end, and look as if intended
to support the roof of the test, though I have not been able to satisfy
myself that they actually reach it. Nor have I been able to ascertain
whether the number of processes is constant, but they have appeared
to me to vary in number from four to seven. They are not visible
looking directly into the mouth of the test, but a glimpse of one or
two may be detected when the mouth is aslant, as the test is made to
turn towards one side. From the usual discoid form of the test it is
not easy to retain it in position on edge to conveniently examine the
processes, and when the test is observed with adherent sand they
cannot be seen at all.”

Bathybius come to life again !—This singular, at one time supposed
animal organism, and which has since been relegated by Professor
Huxley to the mineral world, has been, so to speak, resuscitated by

150 PROGRESS OF MICROSCOPICAL SCIENCE.

the American zoologists. A writer says, as regards Bathybius, which
is now again attracting notice, more however in clerical than in
scientific circles, it may be said that while Professors Wyville Thom-
son and Huxley have been inclined to doubt whether this is an organ-
ism, Dr. Bessels, of the ‘Polaris’ expedition, discovered in Smith’s
Sound a form almost exactly like Bathybius, which, however, he judged
to be still simpler than” Bathybius, and accordingly named Proto-
bathybius. A description and a figure of it are given from drawings
and notes furnished by the author in Packard’s ‘Life Histories of
Animals.’ Even if Bathybius should prove to be inorganic, we have
Protobathybius Robesonii left, and several allied forms of simple
Monera, such as Protameba protegenes, and others, which are simple
drop-like masses of protoplasm, even without a nucleus. All these
animals or plants, it matters not which, but most probably the former,
are placed by Haeckel in his Monera, a division of organisms adopted
by Huxley in a recent paper.

A novel form of Epithelioma is described in an article on the sub-
ject in the ‘Cincinnati Medical News’ for December. The writer,
Dr. W. C. Dabney, says that there can be no doubt that the great
majority of physicians engaged in general practice, who use the
microscope at all, look upon the nest-like arrangement of epithelial
cells as characteristic of cancer, and generally of the ‘“ epithelial ”
variety, so-called. This is the teaching of those works on patholo-
gical histology which are most used in America, and such were the
views which he had been led to adopt in consequence, till a few
months ago, when, on examination of an ordinary wart removed
from the penis, he found a nest of cells, which he could in no way
distinguish from those known to occur so commonly in epithelial
cancer. The little growth was about the size of a large English pea,
and was attached to the prepuce by a broad pedicle. On removing it,
and making a section parallel with the little papilla of which it
seemed to consist, he found it to be composed of epithelial cells,
which had, in most parts of the section, no definite arrangement, but
at quite a number of points they were arranged in nests which were
composed generally of flattened cells on the outside, with globular
ones in the centre, while beyond the limits of these nest-like arrange-
ments the cells were of irregular shape, and had, as previously stated,
no definite arrangement. The whole tumour seemed to be composed
of cells, and there were no cylinders to be found—it being, in this
respect, entirely unlike the generality of epithelial cancers. A careful
examination of a number of sections taken from this papillary new
formation, and a comparison instituted between them and sections
from an epithelial cancer of the lip, has not enabled him to observe
any difference in the structure of the “nests” in the two growths;
and the chief difference, so far as he could determine, was the absence
of the “ cylinders” so frequently found in epithelioma.

How the two eyes of a flounder come to the same side—Mr. Alexander
Agassiz has just published a most interesting fact in natural science.
He thus describes the process by which the young flounder which first

PROGRESS OF MICROSCOPICAL SCIENCE. 15F

has its eyes in the ordinary position, comes to have both organs at the
same side of the body :—*“I captured one day a number of flounders
(about an inch in length) closely allied to the Plagusiz of Steenstrup,
the so-called Bascania of Schiédte ; they were so perfectly transparent
that they seemed the merest film on the bottom of the glass vessel in
which they were kept. They were still entirely symmetrical, the
eyes well removed from the snout, with a dorsal fin extending almost
to the nostril, far in advance of the anterior edge of the orbits of the
eyes. They were of course at once set down (from their size) as be-
longing to a species of flounder in which the eyes probably remained
always symmetrical, and I prepared to watch its future development.
It was therefore with considerable interest that I noticed, after a few
days, that one eye, the right, moved its place somewhat towards the
upper part of the body, so that when the young fish was laid on its
side, the upper-_half of the right eye could be plainly seen, through
the perfectly transparent body, to project above the left eye. The
right eye (as is the case with the eyes of all flounders), being capable
of very extensive vertical movements, through an arc of nearly 180°,
could thus readily turn to look through the body, above the left eye,
and see what was passing on the left side, the right eye being of
course useless on its own side as long as the fish lay on its side. I
may mention here that this young flounder, until long after the right
eye came out on the left side, continued frequently to swim vertically,
and that for a considerable length of time. This slight upward
tendency of the right eye was continued in connection with a motion
of translation towards the anterior part of the head till the eye, when
seen through the body from the left side, was entirely clear of the left
eye, and was thus placed somewhat in advance and above it, but still
entirely in the rear of the base of the dorsal fin extending to the end
of the snout. What was my astonishnient on the following day, on
turning over the young flounder on its left side, to find that the right
eye had actually sunk into the tissues of the head, penetrating into
the space between the base of the dorsal fin and the frontal bone, to
such an extent that the tissues adjoining the orbit had slowly closed
over a part of the eye, leaving only a small elliptical opening, smaller
than the pupil, through which the right eye could look when the fish
was swimming vertically. While the young flounder lay on its side,
the right eye was constantly used in looking through the body, and
could evidently see extremely well all that took place on the left side.
On the following day the eye had pushed its way still farther through,
so that a small opening now appeared opposite it, on the left side,
through which the right eye could now see directly, the original
opening on the right side being almost entirely closed. Soon after,
this new opening on the left increased gradually in size, the right
eye pushing its way more and more to the surface and finally looking
outward on the left side with as much freedom as the eye originally
on the left; the opening of the right side having permanently closed.
I have thus in one and the same specimen been able to follow the
passage of the eye from the right side to the left through the integu-
ments of the head, between the base of the dorsal fin and the frontal

152 PROGRESS OF MICROSCOPICAL SCIENCE.

bone.” The author adds :—“ This observation leads to somewhat dif-
ferent conclusions from those of Steenstrup, who thought he could
prove (from an examination of alcoholic specimens) that the eye from
the right side passed under the frontal bone. This is evidently not
the case here, the eye passing round it, there being only a very slight
torsion of the frontal in this young stage. Although at first glance
this appears so radically a different method of transfer of the eye
from the one described above, yet if the dorsal fin had not extended
beyond the posterior edge of the right orbit the process would have
been the same, as is readily seen. I hope soon to give full details,
with illustrations, of the process of transfer of the eye in its different
stages, in a paper I am preparing on the young stages of a few of our
bony marine fishes.”

The Development of Alge.—This subject promises to be well con-
sidered in the ‘Notes Algologiques, of which the first part has
appeared in Paris by MM. Bornet and Thuret. W. G. F. says of it,
in ‘Silliman’s Journal’ (December 1876), that “the plates of this
fascicule are twenty-five in number, and, in point of execution, are
unequalled by any relating to alge, excepting those which illustrated
Thuret’s articles on zoospores amd antheridia in the ‘ Annales. The
work is to algology what the ‘Carpologia Fungorum Selecta’ of the
Tulasne Brothers is to fungology. The text is no less rich and com-
plete than the plates. A general description of the reproduction
and reproductive organs of different genera precedes the detailed
description of the plates, which, in the present fascicule, represent
species referred to by Bornet in his ‘ Deuxiéme Note sur les Gonidies
des Lichens, or which were collected by Schousboe in Morocco and
determined by Thuret. The notes are a masterly exposition of the
reproduction in the Nostochinee and Floridee, and are so replete
with facts that a single reading barely suffices to give a general
notion of the contents. Particularly interesting are the description
of the reproduction of Calothrix confervicola, and the comparative
description of the fruit of the different genera included by older
writers under Callithamnion. The fertilization of Polyides, similar
to Dudresnaya, is referred to, but will probably be figured later. The
work of Agardh is an encyclopedia in which one may find the name
of any Floridez more easily perhaps than in any other. The work
of Bornet and Thuret has a different object. Determination of names
by a somewhat artificial grouping is subordinated to a true knowledge
of the relations of alge through a study of their minute anatomy and
development.”

The Lymphatics of the Liver.—Dr. W. Stirling says* that Herr A.
Budge,{ from his injection experiments, draws the following conclu-
sions regarding the perivascular spaces of the liver. A closed system
of lymphatics exists in the liver, and is in most intimate relation to
the venous blood-vessels. Within the lobules there are simple lym-
phatic sheaths around the blood-capillaries, which prevent the direct
contact of the hepatic cells with the blood, so that any exchange

* ‘Medical Record,’ December 15. t+ Ludwig’s ‘ Arbeiten,’ Band x.

PROGRESS OF MICROSCOPICAL SCIENCE. 153

between these can only take place through the medium of the lymph.
Just as the blood-capillaries at the margin of the lobules unite into
larger trunks, so the lymph-sheaths pass into lymphatics, which are
placed in the walls of the veins, and by means of the interlobular
vessels pour their contents upwards into the lymphatics of the dia-
phragm, and downwards into those of the hilus.

Microscopic Examination of Hospital Walls.—The ‘Medical Record’
(December 15) says that some interesting facts tending to confirm
previous observations by others have recently been communicated to
the Société de Biologie, by M. Nepveu, of the Laboratory of La
Pitié. A square metre of the wall of a surgery-ward having been
washed after two years, the liquid pressed from the sponge was
examined immediately. It was somewhat dark throughout, and con-
tained micrococcus in very great quantity (fifty to sixty in the field of
the microscope), some micro-bacteria, a small number of epithelial
cells, a few globules of pus, some red blood-corpuscles, and lastly a
few irregular dark masses and ovoid bodies of unknown nature. The
experiment was made with all necessary precautions; the sponge
employed was new, and carefully washed in water that was newly
distilled.

Microscopical Researches on the Growth and Change of the Hair.—
Professor Von Ebner sent in to the Vienna Academy a paper on the
above subject, on the basis of the anatomical facts. Professor Ebner
seeks to elucidate as far as possible the mechanical processes of the
growth and change of the hair. Especially it is proved that the inner
root-sheath is of the utmost importance for the hair formation, and
that the same, notwithstanding its being broken through by the hair,
continues to grow during the whole hair vegetation, and in the under
part of the hair even with greater rapidity than the hair itself. This
information leads to important conclusions, of which one may be
mentioned, viz. that the doctrines laid down by Goétte and Unna are
untenable. Respecting the changes of the hair, the writer defends
the doctrine of Langer, that the new hairs are formed in the old
derma and on the old papilla. The objections to this doctrine are
met by the fact which has been up to the present ignored, that
the papilla, at the expelling of the hair, most regularly advances in
height. The mechanism of this process is circumstantially entered
into. During the upward rising the papilla gets smaller, and beneath
the same is formed constantly from the outer and middle hair-skin-
line a filament which is identical with the hair-stem described by
Wertheim. On the same papilla is formed the new hair. The
papilla by-and-by gets gradually larger again and advances, whilst
the hair-stem disappears.*

Cranial Morphology in the Urodelous Amphibia——The philosophic
anatomy of the skull in these animals has been carefully worked out
by Professor W. K. Parker, F.R.S., who lately read a paper on the

* Weekly Reports of the Royal Academy of Vienna, Natural History Section,
July 20, 1876.

154 PROGRESS OF MICROSCOPICAL SCIENCE.

subject before the Royal Society.* This paper must be read by those
interested in the subject, but we may quote the following passages as
being of special interest :—“ Then, as I am spending my life not to
illustrate the cranial morphology of this type or of that, but as
digging down to find one common root, I have made an incipient
attempt at showing what is common to the whole series of the Verte-
brates—of the brain-bearing Vertebrates at any rate. It is evident
that beneath the neural axis, which arises in ‘ epiblast, there is
a foundation, laid in ‘mesoblast,’ of the whole animal, from its snout

to the end of its tail. This foundation, or rather root-stock, is double, |

and each moiety lies right and left of a truly azygous structure, the
notochord—a structure which, according to some, arises in the meso-
blast also, but which, according to the latest and best observations
(namely, those of Mr. Balfour), arises, in the Selachians at least, in
the lowest layer, the ‘ hypoblast.’ Whether the notochord is meso-
blastic or hypoblastic, at present is not of vital moment to the
morphology of a vertebrated animal: the important points are that
the notochord is universal, and that it always passes some distance
into the skull, There are several important modifications in the
region of the head, as compared with the body generally, that make
the problem of cranial morphology an extremely difficult one. To
mention some, there are: (1) the swelling of the neural axis into
three vesicles ; (2) the flexure of the head upon itself; (8) the de-
velopment of three pairs of sense-capsules, that press upon its sides
and mingle with its structures; (4) the union of a palatal diver-
ticulum with the brain to form the pituitary body, thus arresting
the median notochord ; and (5) the dying out of the pleuro-peritoneal
space in the region of the throat. Thus the modifying causes are
manifold in the head of a vertebrated animal,—some of them showing
their effects very early in the life of the embryo; whilst others, that
relate to the specializations of the parts of the cranium and of the
parts of the face, the parts that encircle the mouth and sense-
capsules and that form the basket-work of the branchial apparatus—
these appear later.”

The Embryonic Membranes in Plants.—Professor Famintzin has
published a valuable paper on this subject in the ‘ Botanische
Zeitung,’ which is thus abstracted in the ‘ Academy’ (December 30) :—
‘“«'The main purpose of the paper is to furnish the proofs of his theory
of the development of the initial layers, or embryonic membranes, in
plants. Hanstem had previously pointed out the existence of three
distinct layers in the developing embryo of Capsella bursa-pastoris,
and several Composite. The further development of these ‘ three
systems of tissues,’ Famintzin asserts, has proved to be perfectly
identical with the formation of the embryonic membranes in animals.
While the embryo is still quite small, and before there is any trace
of the cotyledons, the plerome forms an axile cylindrical cord,
sheathed in two layers of cells, the periblem and the dermatogen.
Soon divisions appear in the dermatogen at the lower end of the

* «Proceedings of the Royal Society,’ vol. xxv. No, 175.

.
a a

PROGRESS OF MICROSCOPICAL SCIENCE. 155

embryo (near the suspensor), and the periblem increases to several
layers on the sides of the embryo, but remains one-layered at both
ends. As Hanstein has already shown, the root-cap and the primary
bark are the result of these cell-divisions. Taking a more fully deve-
loped embryo in which the cotyledons are present as two symmetrical
projections, and rendering it transparent by Hanstein’s method, three
membranes or layers of tissue are as clearly distinguishable in the
cotyledons as in the axile portion of the embryo ; they appear as out-
growths of the corresponding tissues of the axis of the embryo, and
subsequently undergo the same changes. Briefly, says Famintzin,
the principal results of my investigations may be thus expressed.
‘In the earliest stages of the formation of the vegetable embryo three

morphologically distinct layers of tissue appear, which during the ©

complete development of the embryo, and most likely during the whole
life of the plant, retain, with few rare exceptions (the embryonic
vesicle, for instance), their independence, and only certain defined
tissues are formed from them. In other words, they correspond
exactly to the embryonic membranes of the animal kingdom.’ ”

Structure and Function of the Leaves of Dionea.—Two botanists
have been lately engaged in studying these subjects, and their re-
searches have been made perfectly independently of each other—
M. Casimir de Candolle, in the ‘ Archives des Sciences Physiques et
Naturelles, April 1876, and Dr. Fraustadt, in the first part of the
second volume of Cohn’s ‘ Beitrige. As might be expected, in regard
to the anatomy of the leaves they are in almost perfect accord, but in
other respects their conclusions are somewhat different. De Can-
dolle’s experiments extended over a period of only six weeks, and, in
addition to the question of nutrition, he investigated the mechanism
of the leaves. Briefly, his conclusions are these. Animal substances
absorbed by the leaves are not directly utilized by the plant, nor
necessary to its development. The marginal teeth and edge of the
blade of the leaf form a member (organ) distinct from the rest of the
leaf, which explains the reason why their movement is not simul-
taneous with that of the valves of the blade. The stellate hairs and
the glands are epidermal structures, whereas the excitable hairs on
the surface of the valves are outgrowths of the fundamental tissue
beneath the epidermis. The anatomical structure, as well as the
development of the different parts of the leaf, favours the hypothesis
that the movements of the two valves of the leaf depend upon variations
in the turgescence of the parenchyma of the upper surface only of the
leaf. According to both observers, no stomates are present on the
upper surface of the leaf. Dr. Fraustadt’s investigations were of a
somewhat different character. Without entering into them in detail,
we may give the results of his experiments bearing upon the question
of nutrition. The cells of the leaves of Dionza exhibit, in many
respects, an unusual behaviour towards chemical reagents, which
seems to point to the presence of a peculiar substance, the nature of
which, however, nobody has yet succeeded in making out. Appa-
rently it exists in the living cells in acid solution ; consequently it is
precipitated by bases and redissolved by acids. Ammonia colours

156 PROGRESS OF MICROSCOPICAL SCIENCE.

the red glands on the upper surface of the lamina greenish, and pre-
cipitates, in the cells containing starch, a fine-grained substance.
And if the ammonia is neutralized by acetic acid the red colour of
the glands is re-established, and the granules in the cells are dis-
solved and disappear. Adding potassium again removes the colour
and causes the starch-granules to swell up and become transparent.
Finally, the green granules are again precipitated. After carefully
washing out the potassium, and then treating the tissue with iodine
(as iodide of potassium), the cells are uniformly coloured blue or
violet. Dr. Fraustadt also found that the cells of those leaves which
had caught little animals, or had been fed with albumen, contained
no starch, or very much less than those which had access to no
organic food, after these substances had been enclosed a few days.
When dyed albumen was presented to the plant, the colour was
absorbed even into the vascular bundle of the midrib.

On the Eyes of Worms.— A paper of some interest is that of
M. J. Chatin, which was presented to the French Academy (December
18) by M. Milne Edwards. In a previous paper—of which we
have given an abstract—the author described pretty fully the minute
structure of the bdtonnets of crustacea. In the present paper he in-
dicates a series of analogies between the eyes of the annelids and
those of crustacea. The eyes of worms present three distinct types:
(1) In Torrea the eye is extremely perfect, and comprises all the
parts that one sees in the eye of Vertebrates. (2) In the various
Serpule the eye is formed by one or more refractive parts placed
in a generally elongated matrix. (3) In the Polyophthalmie the
organ consists of one or more analogous pieces, but they are sur-
rounded by a pigmentary mass whose limits are undecided. Now
M. Chatin finds that the second group, that of the Serpule, presents a
marked resemblance between its eyes and those of crustacea. Some
genera, as, for instance, Psygmobranchus, show the analogy very
distinctly. Their eyes are, in fact, formed by a piece in which it is
easy to recognize two parts: one superior, refractive, corresponding to
the crystalline lens of authors ; the other inferior, elongated, coloured
reddish orange (P. protensus), and thinning out toward its initial
end. If now we compare this with the arrangement in certain of the
lower crustacea (Epimeria), we easily recognize the complete analogy
between the crystalline lens and the cone, and between the bdtonnet
properly so called, and the lower part brilliantly decorated as above.
The author gives several other instances which support his views.

Examination of the Air—The French Government has set about a
thorough examination of the air of Paris by the Meteorological Depart-
ment. This investigation began on the 1st of January, 1877; and it
is described by M. Marié-Davy, in the ‘Comptes Rendus,’* somewhat in
advance. He states that the reason of this was to seek out if he could
discover the cause of an epidemic which has raged for some time in
their various barracks. Especially was this the case in the barrack of
Prince Eugene, which the War Department at last evacuated. On

* December 27, 1876.

PROGRESS OF MICROSCOPICAL SCIENCE. iy!

examining the water in this place, it was found quite pure. But on
scraping the floor and walls, and placing the dust in the water, a
myriad of moving octrios were seen under the microscope. The pro-
duct in this way obtained from room No. 400 smelt very badly, and
by microscopic examination numerous alge were found, especially
Coccochloris Brébissonii, and also vibrious bacteria and monads. After
twelve hours there were numerous Amebe found. He thinks that
these several bodies have had much to do with the unhealthiness of
the locality. However, more observations will be required ere this
idea is established.

Development of the Heart in the Chicken.—M. Dareste, who is well
known in France for his researches in development, has recently
presented a paper on the above subject to the Academy.* It is to
form part of a work on development, which he is about to publish,
but which will not be out for six or eight months. After describing
the results obtained on this subject by Hensen, Kélliker, and Jusser,
the author passes on to his own results. And he shows very clearly,
by a series of arguments which we must refer the reader to the paper
itself for, that in the development of the heart the two ventricles
are at first completely separated one from the other. Indeed in an
abnormal case he found the two ventricles did not contract simul-
taneously, but one twice as fast as the other. This is wonderful, for
unless the contents of the two cavities differed we do not see how
the circulation could have been carried on. We may observe that the
separation of the ventricles is a permanent affair in the case of the
Sirenia.

Researches on Filaria hematica have been recently made by
MM. Galeb and Pourquier on this subject, and have been published
before the French Academy.t These, however, have done little that
has not been already.done by Dr. Cunningham, of India, whose
work our readers are familiar with. The French authors found
Filariz in the blood of a foetus of a bitch whose heart was filled
with these organisms, but they do not explain how they traversed the
double walls of the placenta in order to pass from parent to offspring.
Of course we do not imagine that these worms were spontaneously
developed, but it is as yet unexplained how they passed through the
placental walls.

A New Nematoid Worm has been found by Dr. Normand in the
bodies of those who have suffered from diarrhoea in Cochin China.

Tape-worms in Rabbits.—Some short time since a letter appeared
in ‘Nature, from Mr. G. J. Romanes, to the effect that, in dissecting
some wild rabbits, he found the intestine full of tape-worms. This,
of course, was an extraordinary fact, for the rabbit is purely an
herbivorous animal. How, then, could the tape-worm have passed
through its cystic stage? The difficulty is now removed by a letter
to ‘Nature’ (February 15) from Mr. R. D. Turner, in which he says:
“JT would suggest that the tape-worm referred to by Mr. G.J. Romanes

* ‘Comptes Rendus,’ December 27, 1876. + February 5, 1877.

158 PROGRESS OF MICROSCOPICAL SCIENCE.

is like the Bothriocephalus of man—perhaps a species of the same
genus. This is not supposed to have a cystic state, but to be deve-
loped from a ciliated embryo taken into the system on raw or badly-
cooked vegetables, which have been watered by sewage from cesspools,
in which the eggs will remain alive for months. In the same way the
eges of the rabbit's tape-worm probably remain in the animal’s drop-
pings till set free in rain as ciliated embryos. As the rabbit feeds on
the vegetation watered by such rain, there is no difficulty in under-
standing how the embryos would reach his alimentary canal.”

Some of the ‘ Challenger’s’ Diatoms.—In the ‘Annals of Natural
History’ for February there is an important paper on “ The Type of
Foraminiferal Structure,” in which the author, Dr. G. C. Wallich,
points out, among other important items, the circumstance that certain
of the so-called diatoms found by the ‘ Challenger’ expedition are
not diatoms at all. He says:—“In the report of the ‘Challenger’
expedition, published in the ‘Proceedings of the Royal Society,’
1876, vol. xxiv. pl. 21, there are three figures which are described as
representing ‘true diatoms, to which the generic name of Pyrocystis
has been given by the discoverers. I am, indeed, grievously mistaken
if these structures bear the slightest affinity to diatoms, or are any-
thing else than true oceanic Noctiluce. It would be just as irrational
to separate the testaceous from the naked Rhizopods, because the
former have hard coverings and the latter have none, as to regard
these new forms as distinct from Noctiluca, because they present a
delicate siliceous wall. The figures of the elongate form, if accurate
representations, as they doubtless are, show at a glance that the
structure is not that of any diatom.”

Gigantic Thread-cells—In a paper read before the Linnean Society,
February 15, Mr. H. N. Moseley described the thread-cells of some
Actinozoa found by the ‘ Challenger’ expedition, which, he said, were
the longest existing forms, being as long as 5 or 6 millimeters, if we
remember rightly.

The Tyndall and Bastian Controversy.—Dr. Tyndall recently, de-
livered a Friday evening lecture before the Royal Institution, in
which we think, contrary to the views held by the ‘ Lancet, February
17, that he once more proved his case. Dr. Tyndall had been un-
lucky in many of his last year’s experiments, and this he clearly
showed to be due to the atmosphere of the Institution being laden
with germs from a quantity of hay which was virtually “teeming”
with them. He then went to Kew, where there is now one of the
finest laboratories in the kingdom, and there all his experiments were
perfectly successful. In every case but one the specimens showed no
trace of life. In that one the experiment broke down and life was
very freely developed. But why was this? simply because there was
a small aperture like a pin-hole in the side of the test-tube. A
perusal of Dr. Roberts’s and Dr. Tyndall’s paper, in the last number of
the ‘ Proceedings of the Royal Society’ (No. 176), will show the reader
that the ‘ Lancet’s’ view of the matter is hardly a justifiable one.

PROGRESS OF MICROSCOPIOAL SCIENCE. 159

MicroscoprcaL Contents oF Foreicn JOURNALS.

Zeitschrift fiir Anatomie und Entwickelungsgeschichte, von W. His
und W. Braune, Band 2, 3rd and 4th Heft. Leipzig, 1876.—A good
paper is that on the Architecture of Bone Tissue, illustrated by a
plate, by Dr. Karl Schulin. In this the author tries to show how the
bone structure between the Haversian canals is arranged. He sup-
poses a certain plan which would give the greatest amount of power
of resistance to the bones, and he endeavours to show that this is
carried out in the structure of certain bones, especially of the skull.—
A paper on “The Aqueductus Vestibuli of Man and of Phyllodactylus
Europeus,” by Professor Dr. Riidinger, of Munich, is for the most
part purely anatomical in the coarser sense of the word. Still the
author refers to the microscopical characters of the lining epithelium,
so that it deserves mention.—A very valuable contribution is that by
Herr G. Schwalbe, “On the Structure of Elastic Connective Tissue,”
illustrated by a beautifully delineated plate. This paper deals ex-
haustively with the subject, extending as it does to nearly forty pages.
The chief fact of importance is that relating to some of the fibres,
which it would seem have a peculiar structure, which appears to endow
them with elasticity. There seems to be a division of the fibre
transversely into a series of particles, with lens-shaped spaces between
them, and it is possibly in this way that their elasticity is provided.—
The Structure of the Hair-glands (sebaceous) and their Muscles is a
good paper by Herr Dr. F. Hesse, Prosector at Leipzig. This is of
interest simply from the fact that the author describes minutely
(from a magnifying power of 600 diameters) the structure of the
peculiar muscles which are connected with the hair-sac. He dwells
at some length on the researches, published in 1875, of W. Stirling.—
On Bone Lymph Canals is a brief note by Dr. A. Budge, of Greifs-
wald.

Archives de Zoologie Expérimentale. Fdited by H. de Lacaze-
Duthiers, Année 1876, No. 2.—This number contains a series of
valuable papers :—“ On the Development of Mollusks,” second paper,
by M. H. Fol, deals with the He‘eropoda; “On a Species of
Infusoria Parasitic on Fresh-water Fishes,’ by M. Fouquet; and
“On the Organs of Sense in the Actiniz,’ by M. Korotneff, which is
illustrated by a splendid series of drawings, which we commend to
Dr. Duncan’s notice. The notes and reviews are also of microscopical
interest, more especially that on the development of Holathuriade,
which is by M. E. Selenka.

VOL. XVII. N

( 160 )

NOTES AND MEMORANDA.

Microscopical Vision.—In the present aspect of this important
question, which is being inquired into by Abbe, Sorby, and others,
the following remarks are of interest. They are made by the Presi-
dent of the Dunkirk Microscopical Society (U.S.A.), Mr. G. E. Black-
ham, in a letter—part of which is private—to the Editor. He says,
speaking of one of the reports of his Society :—“I am well aware
that some of the work done by Professor Smith at this meeting will
not meet with ready credence, especially among those who have on
a priori grounds set the limit of microscopical vision at 80,000 lines
to the inch ; the facts are, however, just as stated in the report, and
I may say that, in the quiet of my own parlour, Professor Smith
showed me the lines of the 19th band on one of Nobert’s recent 19th-
band plates, clearly resolved, with my own ‘ duplex’ 4th objective,
‘ A’—2-inch—eye-piece, on Zentmayer’s army hospital stand, fitted
with thin revolving stage—the illumination being lamp—bull’s-eye
and concave mirror, without achromatic condenser, or other light
modifier whatever.”

Dr. J. E. Smith on Wenham’s Reflex Iluminator.—This Ame-
rican microscopist gives an opinion of Wenham’s illuminator as
follows :—“ My first attempt with the illuminator in the histological
line was over a balsam slide of pavement epithelium from my own
mouth. The first field, as given by the illuminator, reminded me of a
painting depicting the Arctic regions in a gale of wind! I saw
scores of icebergs projecting their long black shadows over the field in
inextricable confusion—any attempt to correct the objective at that
stage of my experience would have been folly. I was very far from
being discouraged, for it was palpable that the very power that caused
the havoc in my field, would, when properly harnessed into the traces,
do yeoman service. Removing the illuminator, I selected the smallest
nucleated scale, and one which was far distant from the larger
organisms, bringing it to the centre of the field and clamping the
object carrier. Again, trying the effect of the illuminator, the result
was similar to that of the initiatory trial. But now, knowing the
exact locality of the scale beyond a doubt, I soon managed to identify
it, and, after correcting the objective, was rewarded by a display of
surface markings that amply repaid all costs. The details of this and
similar investigations with the Wenham illuminator I hope before
long to submit. Those who use the illuminator have noticed the
ease with which blue, red, green, and the intermediate tints are
obtained in the field. Some ten days ago it occurred to me to try
unmodified sunlight with the instrument, presuming that the blue field
due to the reflex might have the same effect as the intervening pane
of blue glass which I had before used and recommended in the ‘ News.’
The experiment was a perfect success, and I saw No. 20 of the
Moller plate, not exactly as coarse ‘as the pickets on a fence,’ but
more like the teeth of a fine-toothed comb. The }th inch solid eye-

NOTES AND MEMORANDA. 161

piece was used and amplified, still I had oceans of spare light, nor was
the definition of the objective at all taxed. These results, it seems to
me, are valuable, in that we can now get rid of the cupro-ammonia
cell, and of the blue glass: neither of these could be successfully used
receiving the solar beam through a closed window. With the Wenham
illuminator I could discover no sensible difference in the definition,
whether the window was open or closed. This alone, in the winter
season, will be a great boon to the microscopist.” *

Cleaning Diatoms with Glycerine.—The ‘ American Naturalist’
(February 1877) says that Mr. James Neil, of Cleveland, uses gly-
cerine as an easy and efficacious means of separating diatom shells
from the foreign matter with which they are naturally mixed. He
fills a 2-ounce graduated measuring glass three-quarters full of
glycerine and water mixed in equal parts. The diatoms, after being
treated with acid and thoroughly washed, are then shaken up in some
pure water and poured gently over the diluted glycerine. If care-
fully done the water and diatoms do not at first sink into the glyce-
rine, but gradually the diatoms sink through the water, and into the
glycerine, preceding the light flocculent matter held in the water.
After a few minutes, a pipe introduced closed through the water and
into the glycerine will bring up remarkably clean diatoms, which are
to be afterward freed from glycerine by repeated washing and
decanting.

Eosin: a New Staining Fluid.—Dr. Dreschfeld states in the
‘Journal of Anatomy’ (vol. xi. part 2) that a solution of eosin, of
1 part to 1000 of water, forms an admirable staining fluid. The
sections to be stained, having been immersed in this fluid for one
minute to a minute and a half, are put for a very short time into
water slightly acidulated with acetic acid, and can then be mounted
in glycerine or in Canada balsam. The advantages claimed for this
fluid by the author are these:—1. The time required for perfect
staining does not exceed one to one and a half minute. 2. The solu-
tion can be kept without altering, and remains perfectly clear for any
length of time. 38. Hosin has the property (probably owing to its
fluorescence) of clearing tissues. 4. It differentiates the component
parts of a tissue, which renders it particularly applicable to com-
plicated structures, as tumours. Dr. Dreschfeld finds it particularly
useful in the examination of nervous tissue. The nuclei, nucleoli,
and processes of the ganglion-cells, and the axis-cylinder of nerve-
fibres, are stained light pink; the areolar tissue takes a much deeper
colour; the medulla of the nerve-fibres, on the other hand, is not
stained at all.

* See ‘ Cincinnati Medical News,’ January 1877.

( 162 )

CORRESPONDENCE.

Mr. Braman oN THE BramuaLL ILLUMINATOR.
To the Editor of the * Monthly Microscopical Journai,’

Sr. Joun’s VicaraGe, near Lynn, February 2, 1877.

Sr1r,—Allow me to say, in answer to the concluding paragraph of
Dr. Ward’s letter on Mr. Van der Weyde’s claim to the invention,
which goes by the name of the Bramhall Oblique Illuminator, that,
so far as I am concerned, it is original, as I had never heard of Mr.
Van der Weyde, or of that other American microscopist who claims
to have used the same form more than ten yearsago. I believe I may
say the same on behalf of Mr. Kitton.

I am, Sir, yours faithfully,
JoHN BRAMHALL.

PROCEEDINGS OF SOCIETIES.

Royan Microscorican Society.
Krine’s Cotiece, February 7, 1877.

Anniversary Meeting.—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.

Mr. Charles Brooke said that, in accordance with notice given at
the last meeting, and in order that the printed list might stand good
for election, it would be necessary to suspend one of the bye-laws ;
and he, therefore, rose to move that Bye-law No. 27, Section 6, be
suspended on that occasion, so far as related to the words “that no
person shall fill the office of President for more than two years in
succession,” in order to enable the Fellows, if they thought fit, to
elect H. C. Sorby, Esq., to the office of President for a second term.

Dr. Millar had much pleasure in seconding the motion.

Mr. Charles Brooke having put the resolution to the meeting, it
was declared to be unanimously carried.

Mr. J. W. Stephenson, Treasurer, read the Annual Statement of
Accounts, which had been duly audited and certified as correct.

Mr. H. J. Slack, Hon. Sec., then read the Annual Report of the
Council.

Dr. W. J. Gray moved “That the Reports now read be received
and adopted, and that they be printed and circulated in the usual
way.”

PROCEEDINGS OF SOCIETIES. 1638

Mr. Frank Crisp seconded the adoption of the Reports.

The President having put the motion to the meeting, declared it
to be carried unanimously.

On the motion of Mr. J. W. Stephenson, seconded by Mr. Thomas
Palmer, Mr. J. Spencer and Mr. T. C. White were appointed Scru-
tineers, and the ballot for the election of Officers and Council for the
ensuing year was proceeded with. At its conclusion the following
gentlemen were declared to be unanimously elected :

As President—My. H. C. Sorby, F.R.S.

As Vice-Presidents—Dr. Lionel S. Beale, Sir John Lubbock, Rev.
W. H. Dallinger, and Mr. Hugh Powell.

As Treasurer—Mr. J. W. Stephenson.

As Hon. Secretaries—Mr. H. J. Slack and Mr. Charles Stewart.

As Council—Messrs. W. A. Bevington, Dr. Braithwaite, Charles
Brooke, Frank Crisp, J. E. Ingpen, E. W. Jones, W. T. Loy, Dr.
Henry Lawson, 8. J. McIntire, Dr. Millar, Thomas Palmer, and
F. H. Ward.

The President, rising to deliver the Annual Address, took the
opportunity of thanking the Fellows for the honour which they had
conferred upon him by again electing him President of the Society,
especially as his election on that occasion required a suspension of the
bye-laws to enable it to take place. He hoped to be able properly to
fulfil the duties of the office, and that he should be able to do, during
the next year, even more than he had done in the previous one. After
reference to those Fellows of the Society deceased during the past
year, the President gave a résumé of his Address, upon the investi
gations which he had recently made into the nature and components
of the loose materials forming the sands and clays, as well as some
sandstones and stratified rocks of Great Britain. The subject was
illustrated by drawings upon the board. (‘The Address will be found
printed in extenso at p. 1138.)

Mr. Charles Brooke rose to propose a vote of thanks to the Presi-
dent for the very able Address to which they had just listened. He
was sure they must all feel that a line of inquiry had been pointed
out which was altogether new, and which was also one which must
certainly lead to some very important results. He had much pleasure
in asking that the Address might be printed and circulated in the
usual way.

The vote of thanks was then seconded by Dr. Millar, and, having
been put to the meeting by the proposer, was carried by acclamation.

The President expressed his thanks for the kind way in which the
vote of thanks had been proposed and received. He did not see why
a Microscopical Society should not deal with all subjects which the
microscope could throw light upon. Some persons might perhaps
look upon the subject which had occupied their attention that
evening as one suited only for a Geological Society, but he begged
to differ from that opinion, and to say that he thought the subject
was one which came strictly within their province, and he believed
that, not only in the field of geological research, but in others also,
there was a great deal to be done by means of the microscope, and

164 PROCEEDINGS OF SOCIETIES.

which therefore came fully within their scope as a Microscopical
Society.

The President announced that, at their next meeting, a paper by
the Rey. W. H. Dallinger would be read, entitled “ Additional Note on
the Identity of Navicula crassiner vis, N. rhomboides, and Frustulia
Saxonica.”

Annual Report of the Royal Microscopical Society.
February 7, 1877.

JoHN Warr STEPHENSON IN ACCOUNT WITH THE RoyAL

Dr. Microscopicat Society. Cr.
1876. £8, d,"|| W876. “3G eee
To Balance brought from By Cash paid for Journal 240 0 0
3lst Dec. 1875 .. .. 247 2 9 || », Rent and Attendance at
» Half-year’s Dividend on | King’s College se yf eS
11027. 13s. 4d. Consols 16 8 7 5 Reporter ve aoe AU 0
» Ditto on 1124/7. 18s. 11d. 16 13 11 | ” Mr. Reeves’ Salary .. 80 0 0
,, Composition Subscription 42 0 0) ;, Commission .. HIG; 0
,, Annual Subscriptions, &e. 418 2 0 » Ray Society for 1876 . feel ve=aN)
sy SOuIMAIS SOG. ee oe) ues S050 , Fire Insurance .. 1 4 0
| », Stationery and | Printing 15 18 9
5) DOOKS neers fe se ys)
> Petty: Cash) 20 Wa. acceso m0 mn
», Soiree Expenses .. 914 6
», Cash paid for 227. 5s. 7d.
Consols... ae Ol 10)
», Book Shelves a5. se Hye alias 5 (0)
» Slate and Stand .. 212 6
| » Instruments and Repairs 819 0
| »» Stamped Cheque-book Oye: (2 |
|| » Balance remaining 31st
| Dec. 1876 os joe) mao emo O ,
£41 17 3) £741 17 3

Jan. 29, 1877. Examined and found correct,

CHARLES JAMES FOX.
F. W. GAY.

Liprary, APPARATUS, AND COLLECTIONS.

The additions made to the library, apparatus, &., since the last
Report are given below.

The Council had much pleasure in responding to the request made
by the Government for aid to the Loan Collection at South Ken-
sington, and sent thereto a selection of instruments of historical
interest.

The books and collections are in as satisfactory a condition as
the limited space and means at the disposal of the Society have
permitted.

PROCEEDINGS OF SOCIETIES. 165

The following are the more important works presented during
the year:

Transactions of the Linnean Society.

Transactions of the Royal Irish Academy.

The Application of Photography to Micrometry, with special reference to the
Micrometry of Blood in Criminal Cases. Illustrated with Photographs. By
Dr. J. J. Woodward.

Medical and Surgical History of the War of the Rebellion, Part 2. From the
Surgeon-General, U.S.A.

Quinology of the East Indian Plantations. By John E. Howard.

Memoire sur les Caracteres Mineralogiques et Stratigraphiques, &e. Par MM.
Poussin et A. Rénard.

Six sets of Photographs, with Pamphlets. By Dr. J. J. Woodward.

Books PuRCcHASED,

Quarterly Journal of Microscopical Science.
Annals of Natural History.

Proceedings of the Royal Society.

Mycographia [cones Fungorum. Parts 2 and 3.

APPARATUS, SLIDES, &C., PRESENTED.

Three Slides of Minerals, from F. Rutley, Esq.
Four Sections of Coal Fossils, from Mr. Norman.
Three Slides of Diatoms, from Mr. F. Kitton.

PAPERS READ BEFORE THE SOCIETY DURING THE PAST SESSION.

Optical, Instrumental, and Technical.

“ On the Characters of Spherical and Chromatic Aberration arising
from Excentrical Refraction, and their Relations to Chromatic Dis-
persion,” by Dr. Royston-Pigott.

“ Ona New Arrangement for Illuminating and Centering with High
Powers,” by Rev. W. H. Dallinger, March Ist, 1876.

“Measurements of Méller’s Diatomaceen-Probe-Platten,’ by E. W.
Morley, March 1st, 1876.

“ A New Microscopic Slide,” by HE. V. Broeck, April 5th, 1876.

“On a New Form of Pocket Spectroscope,” by H. C. Sorby.

“ A Stage Incubator,” by H. A. Reeves, December 6th, 1876.

“ Notes on Micro-photography,’ by Surgeon-Major Gayer, May
drd, 1876.

“On a New Process of Preparing and Staining Fresh Brain for
Microscopical Examination,” by Bevan Lewis.

“ Observation on Professor Abbe’s Experiments illustrating his
Theory of Microscopic Vision,” by J. W. Stephenson, January 3rd,
LST.

Observations upon Mr. William Rogers’ Paper on a Possible
Explanation of the Method employed by Nobert in Ruling his Test-
Plates,” by W. Webb.

“On the Present Limits of Vision,” by Dr. Royston-Pigott, October
4th, 1876.

“On a New Method of Measuring and Recording the Bands of
the Spectrum,” by Thomas Palmer, B.Se., October 4th, 1876.

166 PROCEEDINGS OF SOCIETIES.

“On the Measurements of the Angle of Aperture of Object-
glasses,” by F. H. Wenham, November Ist, 1876.

Natural History and Mineralogy.

“The Identification of Liquid Carbonic Acid in Mineral Cavities,”
by W. N. Hartley, F.C.S., March Ist, 1876.

“On some Structures in Obsidian, Perlite, and Leucite,” by Frank
Rutley, F.G.S., March Ist, 1876. -

“Note on the Markings of Navicula rhomboides,” by Dr. J. J.
Woodward, April 5th, 1876.

“Some Results of a Microscopical Study of the Belgian Plutonic
Rocks,” by A. Rénard, §.J., April 5th, 1876.

“ On the Markings of the Body-scale of the English Gnat and the
American Mosquito,” by Dr. J. J. Woodward, May 3rd, 1876.

“On Remulina Sorbyana,” by J. F. Blake, May 3rd, 1876.

“On the Rotifer Conochilus volvox,” by Henry Davis, June 7th,
1876.

“On the Microscopical Structure of Amber,’ by H. C. Sorby and
P. J. Butler, October 4th, 1876.

“ A Curious Fact in connection with certain Cells in the Leaves
of Hypericum Androsemum,” by W. Hinds, M.D.

“ Experiments with a Sterile Putrescible Fluid exposed alternately
to an Optically Pure Atmosphere,” &c., &c., by Rev. W. H. Dallinger,
November Ist, 1876.

“ Bastian and Pasteur on Spontaneous Generation” (translation),
by H. J. Slack.

“The Markings of Frustulia Saxonica,’ by Samuel Wells.

“Qn Navicula crassinervis, Frustulia Saxonica, and Navicula
rhomboides, as Test-Objects,” by Rev. W. H. Dallinger, December
6th, 1876.

“On the Relations between the Development, Reproduction, and
Markings of the Diatomacee,” by Dr. G. C. Wallich, January 38rd,
1877,

Twelve gentlemen have been elected Fellows, and two have been
elected Honorary Fellows of the Society during the year, and the
Society have to regret the loss of seven ordinary and one Honorary
Fellow.

OBITUARY.

CuristTIAN Gorrrreip Eprensere was born on the 19th of April,
1795, at Delitzsch, in Saxony, of which town his father was what we
may perhaps call “town regent” (Stadtrichter), Even at the early
age of fifteen he evinced a strong taste for the study of natural .
history; but being destined by his father for the Church, he was sent
to study theology at the University of Leipzig. He, however, soon
resolved to devote himself to a profession more closely connected with
his favourite subject, and applied himself to the study of medicine,
thinking it impossible to earn his living by devotion to pure science.
In 1819 he commenced practice, but abandoned it in the course of a

PROCEEDINGS OF SOCIETIES. 167

year, and fairly commenced a career of scientific research, which was
continued uninterruptedly for more than half a century. His early
papers were chiefly on botanical subjects, and his first great discovery,
made in 1820, was that fungi are developed from spores, and not by
spontaneous generation. The minute anatomy of animal tissues also
attracted his attention, but his fame chiefly rests on the many brilliant
discoveries which he made in connection with living and fossil Fora-
minifera, Polycistine, and Infusoria, using this term in the sense
employed by him, which included many organisms now regarded as
plants.

The earliest paper connected with these subjects was published in
1829, and from that date until 1875 there appeared a constant suc-
cession of valuable papers, or separate works, relating to minute
animal or vegetable forms. His last was on marine and fresh-water
dredgings from all countries, published in 1875, when eighty years
of age.

At the commencement of Ehrenberg’s splendid researches the
achromatic microscope was quite in its infancy ; and, if we may rely
on the conclusions to be drawn from a careful examination of the
older microscopes in the late Loan Collection at South Kensington,
something like one-half of Ehrenberg’s work must have been done
with microscopes which nowadays would be looked upon as scarcely
good enough for toys, much less for research. When we reflect on
what he did with such imperfect instruments, and what many of
our present microscopists do with their splendid apparatus, one cannot
but feel that the eye at one end of the tube is, after all, the most
important part of the whole optical arrangement. We all know very
well that Ehrenberg was led into many errors, but, considering the
means at his command and the extreme novelty and difficulty of some
of his investigations, we may be surprised more by the truths dis-
covered than by the mistakes made.

What strikes us most is the vast extent and continuance of Ehren-
berg’s researches. Independent of his great works on the Infusoria,
on Microscopic Geology, and other kindred subjects, the number of
separate memoirs published between 1820 and 1873 was no less than
293; being, therefore, an average of five or six, continued over a
period of no less than fifty-three years. We must forbear to notice in
detail even a mere fraction of these publications. We can scarcely
over-estimate the effect of all this work on the advancement of micro-
scepical science. Perhaps one of the most important conclusions was
that minute organisms have contributed very much to the formation of
thick masses of stratified rocks, and that such deposits as our chalk
are—or, perhaps, still more correctly, were originally—most closely
similar to deposits now being formed in modern oceans. He was
elected an Honorary Fellow of our Society in 1840, and died on June
27, 1876, at the age of eighty-one years.

Epwarp Newmay, F.L.S., &c., was born at Hampstead, on May 13,
1801. At a very early age he evinced a taste for natural history,
which was fostered and encouraged by both his father and mother.
After his school days were passed he resided with his father at

168 PROCEEDINGS OF SOCIETIES.

Godalming, carrying on the business of a wool-stapler, but all the
while devoting himself to the study of his favourite subject. In 1826
he removed to Deptford, where he engaged in the business of a rope
manufacturer. It is said that in his garden there he specially culti-
vated such flowers as attract many insects, and devoted much time to
the study of their habits. He was one of the original members of the
Entomological Club; and when this club started the ‘ Entomological
Magazine, he was chosen to be its first editor; and for upwards of
forty years the collection of the club was under his personal care.
Towards the end of 1840 he became connected with a publishing firm,
and conducted the business until 1870, during which interval were
brought out several valuable works on insects and ferns, to the study
of which plants he had devoted much attention. Amongst other pub-
lications may be mentioned the ‘ Zoologist, of which no less than
thirty-three annual volumes were published under Mr. Newman’s
supervision.

In 1858 he became the natural history editor of the ‘ Field,
and continued to fill that post until his death. Amongst his papers
in this periodical may be specially named those on economic entomo-
logy, being perhaps the first to point out to agriculturists the true
way to deal with their insect enemies. Mention may also be made of
his two valuable works on British Moths and British Butterflies,
which latter was written by him when in his seventieth year. He
died on the 12th of June, 1876, at the age of seventy-five, having by
his many separate works and very numerous original memoirs, and by
means of the Journals published under his editorship, largely contri-
buted to advance and disseminate a knowledge of various important
branches of natural history. He was elected a Fellow of our Society
in 1840.

Though Dr. Francis Srpson, F.R.S., was elected a Fellow of the
Microscopical Society in 1853, his scientific investigations were only
indirectly connected with microscopical research, and had more special
reference to general human anatomy and to the practical application of
remedial measures. He was born in 1815, near Maryport, in Cum-
berland, and received his medical education in Edinburgh and London.
For thirteen years he was resident surgeon to the Nottingham Hos-
pital, after which he removed to London. The subjects to which he
directed his attention were chiefly more or less closely connected
with the physiology and pathology of respiration ; but he was also the
author of a valuable work on medical anatomy. He died suddenly at
Geneva, on the 7th of September, 1876, aged about sixty, from the
bursting of an aneurism, when almost in the act of telegraphing to
say when he would arrive at his residence in London.

Wuttram Detrertier, born December 23, 1800, died July 15, 1876.
Joined the Microscopical Society in 1847. For more than twenty-five
years he was an enthusiastic worker with the microscope, and in-
terested himself in its optical and mechanical improvement. He
acquired great skill in the display of difficult objects and in testing
glasses, and when Messrs. Powell and Lealand contemplated the im-
provements carried out in their first-class microscope, he entered

OO ee ee eee

PROCEEDINGS OF SOCIETIES. 169

warmly into their plans, and the first instrument of the new pattern
was made for him.

Joun Newton Tomurns, born 1812, died 1876. Joined the Society
in 1857. He studied surgery under Joseph Henry Green, and passed
with distinction through the medical curriculum of St. Thomas’s
Hospital. He was for many years Inspector of the National Vaccine
Institution, and was a Fellow of the Royal College of Surgeons, and
of the Royal Botanical and Zoological Societies. He formed an ex-
tensive collection of microscopes, apparatus, and objects, and for many
years promoted microscopical pursuits by scientific gatherings at his
house in Fitzroy Street, which afforded opportunities for examining
novelties and for friendly discussion.

The Secretaries have not been able to obtain any biographical
information concerning the following :

Chas. Gilbertson, elected Feb. 13, 1861, died Dec. 10, 1876.

Henry Hopley White, elected April 1841, died Dec. 10, 1876.
Andrew Yeates, elected March 1854, died Feb. 16, 1876.

Donations to the Library since January 3, 1877:

From
Nextt Camm WV COKLY iia, oi, chi nacam occu atone! adem Manu Rae eamora! nced idan aoe nen Mantors
JANe Tei, ACCA 55a oot Comme nog ior mcd EHOmy tam neo Ditto.
Society of Arts Journal . «es, SOCIELY.

Annuaire de L’Observatoire de Montsouris pour ‘VAn 1877 7.
Memoir of the Life and Works of Edward Newman. By his Son.. Author.

Bulletin de la Societé Botanique de France, 1876 .. .. .. «. Society,
Annales de la Société Belge de Microscopie, 1875-6 Ae x Ditto.
Bulletin des Seances de la Société Belge de Microscopie, 1874-5 oa, 1 Detto:
Transactions of the Linnean cugre: “Two parts: ) <6) Uae ney a aitos

Set of Photographs .. pegs Se dls Rit RT Oliver, Chicago.
Popular Science Review. "No. 1 ' Now Gericd =. Mas! i. 20Rs .. Publisher.

Dr. John Habirshaw, and Frederick Habirshaw, Esq., of New
York, were elected Fellows of the Society.

Water W. Reeves,
Assist.-Secretary.

Mepicat Microscopicant Society.

Annual General Meeting, January 19,1877. Dr. J. F. Payne,
President, in the chair.

This was the first meeting held in the new rooms of the Society,
6, Pall Mall Place, W.; and the additional comforts and advantages
offered over the old room seemed to be fully appreciated by those
present.

The Secretary’s Report for the year 1876 was read.

The following are the names of the communications read before
the Society during the past year :—President’s Address, Dr. Payne.
Development of New Blood-vessels, Dr. Thin. Browning’s Triplet
Mr. Jabez Hogg. Modification of Pritchard’s Microtome, Mr. Giles.
Hints on the Systematic Study of Histology, Dr. Woodman. Cirr-
hosis of Liver in Child, Mr. Needham. Freezing Microtome, Mr. R.

170 PROCEEDINGS OF SOCIETIES.

Williams. Microscope for Viewing Circulation in the Frenum
Lingue, Dr. U. Pritchard. Carcinonia of Liver simulating Cirrhosis,
Dr. Goodhart. Myeloid Sarcoma, Mr. Needham. Organ of Corti in
Mammals, Dr. U. Pritchard. Rodent Ulcer, Mr. Golding-Bird.

The soirée of the Society was held on June 80. Of the fifty-four
microscopes exhibited, twenty-four were devoted to a series of typical
tumours ; besides these, a variety of instruments and photographs
was shown.

The number of members of the Society in December 1876 was 129.

Several presents during the past year both of books and specimens
were received ; and upwards of seventy different preparations besides
apparatus were exhibited at the close of the meetings, in the same
period.

The Treasurer’s Report showed on December 31, 1876, a balance
of 301. 9s. 3d. against one of 201. 9s. at the same time in the previous
year. The soirée expenses amounted to 197. The actual increase in
the income of the Society was therefore nearly 301.

The retiring President then delivered his address.

He congratulated the Society upon its numbering 122 paying
members, and thought that just at this time it might be said to be
passing through a crisis; it had outgrown its developmental stage,
and now hoped for something better. Originally designed to be of
service to medical students, it soon found its sphere of action among
those far senior to students; and he would say that in his opinion
this Society offered a more congenial field for the investigation of
histological pathology than any other in London.

One function he deemed specially belonging to the Society, i.e. to
study the influence of histology—normal or pathological—in every-
day medical practice; this included a very large but very important
field if we include its relation to hygiene.

A clearer knowledge of tissues had helped us to understand more
of pathological conditions ; gave also a clearer precision in diagnosis,
and sometimes even a general hint as to prognosis and treatment,
Such a subject as “ degeneration,” how different was its aspect now
to that of the prehistological period! Fatty infiltration was now
easily distinguished from “ fatty degeneration,’ while the practical
bearing of this was found in the recognition now of sudden death
from a fatty heart—a condition proved by histological investigation,
and even admitted sound in courts of law. Again, with regard to
tumours, what numbers of varieties were classed under the one head
malignant or even cancer, now known to be perfectly distinct from
each other, and how usual was it to appeal to the microscope ere the
surgeon gave an opinion as to the recurrence of the disease.

Several other instances of the use rendered to practice by the
microscope were quoted, particular stress being laid upon the help it
had been in elucidating the intricacies of Bright’s disease. Chorea
was brought forward as showing what yet remained to be done, for
till its histological pathology were determined, who could say that it
was not the expression of several diseases ?

PROCEEDINGS OF SOOIETIES. 1 ipa

In conclusion, the President remarked that this anatomical know-
ledge was after all but the beginning of medicine. Still it was an
improvement upon the time when the physician walked on air, so
to speak—having nothing but symptoms to guide him—and given an
anatomical basis, it would for most diseases at least be a histological
one. The difficulties of investigation were great, and the slowness
of discovery was not the fault but the misfortune of the histologist.

LIvERPOOL Microscoproan Soctrety.

The ninth ordinary meeting of this Society was held at the Royal
Institution, Friday, December 1, the Rev. H. H. Higgins, A.M.,, in
the chair.

Captain Jno. H. Mortimer, of the U.S. ship ‘ Hamilton Fish,’ an
associate member of the Society, exhibited a number of marine
specimens which he had presented to the Free Public Museum. He
also communicated some interesting facts in connection with the
Physalia pelagica, known as the Portuguese man-of-war, the tentacles
of which are of great length, consisting of a muscular band studded
on its margin by rows of beads, each bead being a mass of small
spherical cells, each of which contains a small spiral stinging thread,
coiled up inside. Portions of the tentacles had been mounted for
microscopic examination, and under a power of 500 diameters the
cells and spiral contents were easily seen. Captain Mortimer stated
that he had frequently witnessed the discharge of the stinging threads
from the cells, and that the stinging power was perceptible some days
after the death of the animal. He believed that the above facts were
new to science.

The paper for the evening was on “ Lines of Animal Life,” by
the Rev. H. H. Higgins. The paper was illustrated by diagrams,
especially by one of large size representing a Stammbaum des Thier-
reichs, or genealogical tree of animals, enlarged from ‘ Grundriss der
Zoologie, by Professor G. v. Koch, published in part, during the
present year. \

A short and interesting discussion followed, after which the
meeting concluded with the usual conversazione.

San Francisco Microscorican Society,

A meeting of the San Francisco Microscopical Society was held
December 21.

Mr. Isaac Lea donated to the cabinet a sheet of Phlogopite Mica
from Canada, and another of Muscovite Mica from Chester County,
Pennsylvania. Mr. Lea also exhibited a new micaceous mineral
known as Hallite, a film of which he placed on the stage of the
microscope and called attention to its characteristics,

Mr. Hanks presented a sample of diatomaceous earth from a
newly discovered deposit in Ione Valley, Amador County, California,

172 PROCEEDINGS OF SOCIETIES.

A small portion hastily prepared showed several forms, mostly Dia-
toma and Navicula.

Four slides, being sections made in different directions of a hard
deposit showing woody structure, found in the body of the Mount
Diablo coal vein, and termed “Nigger Head” by the miners, were
donated by Mr. 8. B. Christy. On examination, the wood fibres were
clearly shown, and their general appearance was that of the oak.

Mr. Hanks handed in a report on a sample of (so-called) silver
mud from Oregon.

Mr. Kinne exhibited several slides of diatoms mounted by Professor
H. L. Smith, of Hobart College, Geneva, New York, which had been
received in the way of exchange, and called the especial attention of
the members to the preparations of Professor Smith and his authentic
series of diatoms. -

Mr. J. P. Moore handed in a new fungus, which he described at
length, and has named Lentinus aurantius.

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THE

MONTHLY MICROSCOPICAL JOURNAL.

APRIL 1, 1877.

1.—Additional Note on the Identity of Navicula crassinervis,
Frustulia Saxonica, and N. rhomboides.

By Rev. W. H. Dauuinearr, V.P.R.M.S.
(Read before the Royau Microscopican Society, March 7, 1877.)
PuaTE CLXXVI.

Ir would have been a matter of much interest to me to have been
present at the discussion which followed upon the reading of my
paper upon the above subject in December last. I might have
been able to afford or to evoke explanation that would have served
to further elucidate the subject.

it The only report of the discussion I have access to is that given
in the January number of the ‘M. M. J.,’ which doubtless is sub-
stantially correct. In the interests of science, and with a simple
desire to elicit truth, | may be permitted the privilege of this note
upon some of the statements it contains.

And first, of course my paper did not aim at proving, or, on
my own authority, even asserting, the ¢dentity of the diatoms in
question. I simply accepted this on the authority of Professor
H. L. Smith and Mr. Kitton, which to myself was, and still is, per-
fectly competent. But accepting the identity of these forms thus
established, I sought to augment its value by a fact—in itself of
some optical interest—that all these forms were in ultimate struc-
ture precisely alike; so that, using the lowest power that would
reveal the beaded arrangement on the surface of the smallest forms,
we could, by using successively larger forms, with the same power,
see precisely the same arrangement with increasing clearness and

ease.

DESCRIPTION OF PLATE CLXXVI.
Fic. 1, A, B, C, D.—Four forms of NV. rhomboides in a gathering from “ Cherry-
field,” showing modifications of outline, with the existence of the links uniting the
two extremes (A and D). @ in A shows that the striation was that belonging to

N. rhomboides.
Fic. 2.Similar examples from specimens taken in the living state at Llyn-

cum-Bychan. — ‘ ;
Fic. 3.—Similar evidences of change of form in the smaller frustules known

as IV. crassinervis. en
Fic. 4.—Different modifications occurring in the apexes A, B, C, of the mid-

ribs of these diatoms.

VOL. XVII. O

174 Transactions of the Royal Microscopical Society.

Now the report of the discussion affirms that “ Mr. Ingpen
suggested that, after all, the question of genus and species depended
upon difference in shape, and not upon the absolute number or
fineness of the lines.”* From which I should gather that the
identity of ultimate structure which I pointed out, taken together
with the opinion of the authorities named, had left the speaker
unconvinced of the identity of the forms in question; since
there were palpable though minute differences of shape in the
drawings submitted. Now I have not the slightest desire to
defend or seek to sustain the identity. This is in far better hands;
and the facts I presented remain the same, whether the three
forms be identical or not. But the position taken by Mr. Ingpen
involves a biological question of large importance. Every possessor
of a microscope knows that if there be one thing that is permanent
in Navicula and Pleurosigma, it is not necessarily the tenuity or
coarseness of the striation, but its arrangement; and it was to
this that I specially called attention in the forms in question. On
the other hand, I am prepared amply to prove that the “ shape”
of these diatoms is subject to almost infinite variation: small in
any given case, doubtless, but occurring in every conceivable
direction. Nor am I alone in this affirmation. I number amongst
my friends and acquaintances many amateur, and several profes-
sional, mounters of diatoms; through whose hands, and under
whose eyes, millions of certain forms pass every year; and with-
out a single exception they assure me that between any two con-
trasted and comparatively unlike forms of the “same species” they
can find almost every intermediate grade or link.

Now the point in question is, are we to establish a species upon
a variable or an invariable characteristic ? Is specific identifica-
tion to depend upon that which is always changing in indefinite
ways, or upon that which practically never changes ?

My first great lesson in biology was learned, incidentally, many
years ago, from Professor W. K. Parker, who dispelled for ever my
hard-and-fast view of species in Foraminifera by showing me every
conceivable link between two species. The meaning of it never left
me; and supplied by him with a rich store of foraminiferal material
from almost every part of the world, I quietly worked over hun-
dreds of thousands of forms; and, so far as the mere shell was con-
cerned, proved to myself clearly that many so-called species were
merely extreme modifications of the “species ” to their right or left,
and that every intermediate modification could be found; a truth
which has had ample illustration from Professor Rupert Jones in
our recent ‘ Transactions.’ +

But years of study have convinced me further, that this
mutability is not confined to this group of the Protozoa. It is

* (M.M. J.’ January 1, 1877, pp. 52, 53. + ‘M.M. J.’ vol. xy. 61.

Identity of Navicula crassinervis, &e. By W.H. Dallinger. 175

everywhere manifest, where from their extreme minuteness and
multitude, large numbers of microscopic organisms can be con-
stantly compared.

It is pre-eminently true, for example, of the desmids and the
diatoms. Of course I need not remark that the mere study of
mounted specimens is utterly incompetent for proof in such an
investigation. One might as well attempt to generalize upon the
osteological characteristics of a given skeleton by the observation
of a limited number of specimens seen through the glass fronts of
museum cases. It can only be done, as the Fellows of this Society
well know, by the careful examination of unmounted material in
every variety of condition.

I have already said that my knowledge of the Diatomaceze does
not extend much beyond the silicious frustules ; whilst I have spent
comparatively little time in endeavouring to accomplish difficult
feats with test-objects. But a working microscopist must have a
set of crucial standards, thoroughly known to himself, to serve for
comparison ; and N. rhomboides in its several varieties was very
early adopted as mine: hence I have had an interest in this frus-
tule which has extended over years ; and especially since the pro-
minence given to “F', Saxonica” and “N. crassinervis” I have
examined very large quantities of material derived from both
England and America. It is my habit to make a drawing of any
fact of moment in any of my observations; and I invariably
do this in relation to variations of form in any well-known object
or objects. Since reading the rule given by Mr. Ingpen, on which
the determination of genera and species is said to depend, I have
turned over the leaves of my folio, and have found some singularly
suitable cases of variation in the “shape” of N. rhomboides (of
course including F. Saw. and N. crass.), which are of considerable
service; all the more indeed that some of them have been drawn
for years, and all were drawn in entire independence of the question
in hand.

In Fig. 1, Plate CLXXVI., are the outlines of four frustules
taken from a gathering of “ Cherryfield” rhomboides. They were
of course drawn at different times, and from different “dips” of the
material, and are doubtless not commonly to be found ; but whoever
is supplied with sufficient material and patience might, I am con-
vinced, select and arrange frustules precisely in the order in which
they stand in the Plate. Apart then from the general symmetry,
if the ends of the frustules drawn be examined, it will be seen that
between A and D there is a remarkable difference; but if B and C
be inserted in order between them, we have comparatively easy
steps from the one to the other.

Now the only diatom that I know of that in all respects comes
near to A and B is Navicula cuspidata; but (1) as a rule the

02

176 Transactions of the Royal Microscopical Society.

apexes of the frustules of this form have no constrictions as seen in
A and B, and never, so far as my knowledge goes, a constriction so
great as in A; and (2) although the striation is, in a general
sense, the same as in N. rhomboides, anyone thoroughly familiar
with both could never mistake the one for the other; and to show
that the character of the beading is distinctively that of rhomboides,
a portion has been carefully drawn at 8, A, Fig. 1. This was done
with a magnification of 450 diams., and reduced; while the same
nature and arrangement precisely of hemispheres or beads were
demonstrated in each of the other three forms in Fig. 1.

The point is, if “shape” be the characteristic on which the
determination of “ genus and species” depends, then surely A, B, C,
and D are each of them separate species! Moreover, at times it
happens that the two ends of a given frustule are not absolutely
like each other. In Plate CLXV., belonging to my paper published
in the last Journal,* it will be seen that in Fig. C the right end of
the frustule is not like the left one. This is strictly true to nature.
A constriction is found at one end and not at the other ; does this
make it, and similar forms, specifically different? It was stated in
the discussion that the drawing of the large specimen which I had
sent to the Society had not the “rhomboidal outline”; but if I
had considered that “outline” of the slightest moment, it would
have been an easy matter to find one that had. Do I rightly
understand that such a specimen, if found and presented, would
have to be considered a distinct species from the one drawn ; and
which one of the speakers (Mr. Ingpen) declared “he should hardly
eall a rhomboides at all”? If this be true, I can only say that
there is, in what is now known as N. rhomboides, plenty of work
for those who desire to engage in the labour of describing and
naming species,

But it appears to me that this canon for determining the
generic and specifie differences of diatoms cannot hold good. It
certainly must be rejected by the biologist. The differences be-
tween A and D, Fig. 1, are not greater than those seen in many of
the varieties of several species of fern ; nay, they certainly are not
greater than the difference existing between a bulldog and a grey-
hound, or between a “ pouter” and a rock-pigeon. And I think
that we should therefore have no right to consider them specifically
different, even 2f the intermediate links could not be found; which
they certainly can.

But whilst we have all this variation in form, there is one
characteristic that is practically unchangeable; it is the character
of the “striation.” It is perfectly true that, although it is the
rule that the smallest frustules have the most delicate striation, it
ig not (so far as my experience goes) invariably so. Small frustules

* The present paper was sent to the Secretary in January, but could not be
read until March, the Presidential Address intervening.

Identity of Navicula crassinervis, &e. By W.H. Dallinger. 177

may have relatively coarse striation. But the arrangement of the
hemispheres is, in frustules of all sizes, unalterably the same.

Now as we do not select the variable but the invariable
characteristics of the dog to define it specifically, on what principle
should we ignore an énvariable characteristic of N. rhomboides
(and all other Naviculz), and attempt to determine it specifically
upon characteristics which are found, when large numbers are
examined, to be constant only in their variability ?

That this variation is ever recurring, I may further illustrate.

I have lately been examining a fine gathering of N. rhomboides
from Llyn-cum-Bychan, North Wales. The frustules are very
large, and the beading or striation comparatively coarse. They
were taken in the living state, and only cleaned for examination,
and not for mounting. Fig. 2, A, B, C, gives the outlines of forms
of frustules found repeatedly. I need not point out the varieties
of form or “shape” which they present; they are sufficiently
obvious. But I may remark that in all the “striation” was
identical. Now I would ask, do these varieties of “shape” con-
stitute specific differences? or rather, are they held to do so?
Because, if they are, we should have a distinct and scientific method
for their detection.

Again. In an examination of a good-sized pocket-collecting
bottle full of “ material,” in a well-cleaned state, of smaller forms,
such as have been called F. Saxonica and N. crassinervis, I have
detected and drawn the forms seen in Fig. 3, A, B, C, no less than
five times, quite independently of each other ; but the striation was
alike in all.

Finally, the “nodules” were commented on as exhibiting
variety, In my drawings; and this was taken as, apparently,
important, and the form of the nodule combined with the “ shape ”
of the whole frustule was suggested as the basis of specdfic de-
markation. I can only say that it would have been by no means
impossible to have selected “nodules,” in every case, alike; and
however unlike any two frustules may be, it would be possible to
find the intermediate links. In Fig. 4 are the midribs of three
forms, occurring in the Llyn-cum-Bychan and “ Cherryfield ”
gatherings not infrequently; and the same are also to be found
in “Lancashire” and “Bennis Lake” cleaned material. These
special varieties were drawn from the Llyn-cum-Bychan speci-
mens, and it will be seen that B is simply a link between the
extremes A and ©. And whilst it is not invariably so, I find a
tendency towards the association, in the frustules, of such a nodule
as C, Fig. 4, and such a termination or apex as A, Fig.1; whilst a
midrib terminating as in A, Fig. 4, is associated with such an apex
as C, Fig. 1. This tendency is (quite accidentally) depicted in the
drawings sent with my last paper, and still preserved in the Plates.

So far am I from seeing the need of multiplying species on

178 Transactions of the Royal Microscopical Society.

what, in the light of the facts I submit, appear mistaken grounds,
that I am the rather inclined to see how very many of them might
be shown to glide insensibly into each other, having no rigid line
between. But this of course would not be enough, unless the
developmental history in all the said cases were coincident or nearly
approximate—a matter on which I cannot speak. But when, on
good authority, three Navicule, called separately by specific names,
are affirmed to be capable of being considered one species, so far as
their life-history is concerned; and when it is further shown that
the “striation”—a permanent feature—is the same in each; in
consideration of the fact that both the “shape” of the outline of
the frustule and the form of the “nodules” are constantly subject
to minute variations, it appears to be a case, fairly made out, of
specific identity. This, however, is, comparatively speaking, a side
issue ; the great point is, whether it is possible to make what are
shown to be the variable features of a diatom—taken in entire
independence of its life-history—the elements for determining its
species ?

There are three things in most Navicule that vary: (1) the
general outline of the frustule, (2) the midrib as a whole (although,
so far as my examination goes, it is much less variable than the
outline of the frustule), and (3) the tenwity of the beading or
striation. There is one thing (broadly speaking) which is in-
variable—it is the character or arrangement of the beading.*

* T write thus guardedly because I am convinced, as I have already hinted,
that with a complete knowledge of the life-histories of all the forms of the Navi-
cules there might be an immense reduction of what are now known as specific
forms. ‘Take, for example, such a prominent form as NV. granulata and compare
with it WV. latissima, N. humerosa, and N, brevis on one side, and NV, marina, N. pusilla,
and J, carassivs on the other side, and I suspect that complete search would find
all the intermediate forms. In like manner there can be but little question that
in either old or living forms the intermediate steps between JV. rhomboides and
N. cuspidata might, although perhaps with difficulty, be found.

The transition forms between Pleurosigma fasciola and P, macrum and P. pro-
longatum are almost at hand without searching; and I imagine that many of us
who have examined a large number of slides or “ material” of the forms P. angu-
latum, P. quadratum, and P. elongatum have often wondered at what point the one
ceased and the other began. Of course if their life-histories are essentially different
from each other, then their remarkable similarity and blending into each other
must be regarded merely as coincidence, or in some sense “mimicry.” But if
their developmental histories only differ enough to account for their differences
of form, then I think such forms extremely instructive and well worthy the care-
ful study of those who seek for direct and living proof of developmental changes
in existing organisms: a matter much more readily discovered in minute forms,
seen together in enormous numbers, and subject to critical investigation in their
entirety, than in the larger and more complex organisms, which, when taken in
the greatest numbers in which they can be found, for critical examination, are
but, relatively, few indeed.

In fact, therefore, in saying that even the arrangement of the beading in the
diatoms, chiefly discussed in the above “ Note,” is permanent, I merely mean
that it is so relatively to the other parts; but in all probability this permanence
is only, in reality, an indefinite persistence, a feature, that is to say, immensely
jess liable to change or vary than others.

Gu, 1798")

I—The Exhibitor: a Novel Apparatus for showing Diatoms, &e.
By the Hon. and Rey. the Lord 8. G. Osnornz, B.A., F.R.M.S.

Witx you kindly permit me to introduce to your readers a little
addition to the apparatus of a microscope, which I am sure will
well repay its cost, and the little practice in its manipulation,
required for its perfect success.

In nearly thirty years’ enjoyment of the microscope—using it
for many hours on the greater proportion of my days, applying it
to all kinds of investigation—I always coveted some simple means
of getting a good oblique light for illuminating, under the higher
powers. I have bought and borrowed a good many ingenious in-
ventions for the purpose, and have generally succeeded in getting
fair results, but always with more trouble than was quite agree-
able, to say nothing of the expensive nature of the means used.

After a great deal of experiment, and much hard work, with very
indifferent tools, I am at last quite satisfied. I have for the last
few months had more enjoyment from the microscope than I ever
had before, and this from a very simple contrivance. The Dia-
tomacez I had observed under other modern inventions, but until
now I never saw their real beauty, or got such satisfactory informa-
tion as to their construction.

I will now give the plainest description I can of “ the Exhibitor.”
I take a “Darker” stage, as used for polarizing. I have two
counter-sinkings made on its stage front in the revolving ring;
one, the top one, rather larger in circumference and shallower than
the lower one. Into the lower “sinking” I drop a disk of
blackened metal with a small kettledrum lens mounted in the
centre. Into the upper “sinking” I place metal disks with certain
apertures made in them; the front of these disks is just level with
the face of the stage, the back close to the front of the disk holding
the small lens.

I have a fine screw-worm cut into the back part of the re-
volving ring, coming up just below the lower counter-sinking. Into
this screws a ring of brass carrying a bull’s-eye or kettledrum lens,
of about the diameter of a shilling. The screw movement having
a milled edge, it can thus be focussed as required with the small
upper one.

It will be at once seen that the Exhibitor is thus nothing more
complex than a Darker stage with two kettledrums, the larger
receiving the light from the lamp, transmitting it to the small
one, which latter then delivers it at the back of the metal disk
which is flush with the front of the stage, the screw movement
enabling the observer to focus the two drums.

As to the apertures to be cut in the metal disks, after a great

180 The Exhibitor. By the Hon. and Rev. the Lord 8. G. Osborne.

deal of study I have arrived at the conclusion four such apertures
will meet all that can be desired. No. 1, a fine “slit,” in length
about the diameter of the upper “drum,” i the centre. No. 2,a
similar aperture, a little way, say not quite its own length, from
the centre. Nos. 3 and 4, a pin-hole and triangle, also a little out
of the centre; these may all be cut in one disk.

On the stage I have two steel springs for holding the slides,
giving the means of shifting them in any direction.

. Now for the modus operandi. Having screwed the lower drum
home to the extent of the screw, drop in the disk with small drum
(I have three of different diameters and projection); on this place
the aperture disk; place and cramp the Darker on the stage; turn
the mirror, and place the lamp so as to get the aperture lighted up,
but not with the brightness as with direct illumination ; put on a
slide, say of Angulatum (I prefer those of “ Moller”); adjust the
mirror until you get a rather red appearance on the slide at the side
farthest from the lamp. Focus down on this: when you come on
a bright clear light, like that obtained from ordinary sub-stage
illumination, by moving the stage laterally you will arrive at a
portion of the slide with darker and darker background as you con-
tinue to move it. It will now depend upon manipulation of the
mirror to bring the object on this ground to its best definition. A
little practice soon makes this easy. Supposing you have got an
“ Angulatum” well shown—i.e. on dark ground—clear and erisp ;
turn the milled head of the Darker stage and you will thus
intensify or moderate the light. Having found with any one
aperture good definition of any one object in a slide, with your
fingers you can bring any specimen in the slide over this spot.
I have thus brought every single object in the Typen-Platte of
Moller successively in view, developing their respective beauty in
a way I had hardly thought possible.

I rarely use a mirror, infinitely preferring the Abraham’s achro-
matic prism adjusted to the mirror bar; I can by my hand so
alter the direction and amount of light with this, 1 desire nothing
better.

I use the ordinary Bockett lamp and condenser, with a small
flame edgeways to the prism.

I have worked of late chiefly with a },th of Zeiss, which I find
quite capable of resolving almost every test on which I have tried
it: it brings out both sets of lines on the Rhomboides, showing
where they intersect. A 4 inch of Andrew Ross also gives me
wonderful definition. The 4 and 1 inch of the same maker, with
binocular, the objects on pitch-black ground, bring out many with a
distinctness I have failed to get any other way.

I prefer objects mounted dry, but seldom fail with any; asa
proof of the way I now get definition; having dissected and
mounted the gizzards of the Rotifers, 1 thought I knew their

The Phytoptus of the Vine. By Prof. Giovanni Briosi. 181

mechanism well; I now find I had never before seen a row of
teeth, shown clearly under the Exhibitor. I use it now for white-
light illumination ; indeed, I scarcely use any other illuminator.

It requires practice and patience to master its manipulation, but
well repays it. p

I have placed my models in the hands of Mr. Baker, of High
Holborn, Mr. Curties having been here to see me work the instru-
ment, and having lent me great assistance in getting lenses, &c.,
made for me. He has fitted one for me exactly as described
above, and I find it perfect in use. I have no doubt but he will
have them constructed at a moderate price, and show their use to
anyone who may apply to him.

I shall be more than satisfied if any of our Fellows get a tenth
part of the pleasure I have had in the use of this little affair.
That it may be capable of improvement I can conceive, and shall
be most glad if it is so improved. by those who are more scientific
than myself.

SIDMOUTH.

III.—On the Phytoptus of the Vine (Phytoptus vitis, Landois).*

By Professor Giovanni Briost, of Palermo.

Pirates CLXXVII. anp CLXXYVIII.

Marcetio Matpieut has been the first to investigate scientifically
this evil, which attacks many other plants besides the vine.

This disease consists in a kind of protuberance which is formed
on the leaves, which in consequence assume a characteristic speckled
aspect.

These protuberances, galls, or cecidii,t have, for the most part, a
roundish or oblong, sometimes an irregular form, especially when
through spreading they run one into another, assuming in conse-
quence various sizes, so that leaves are found (at least at Favara)

* Translated from the Italian by W. R.

+ Professor Targioni Tozzetti proposes for this disease the name of Zrinosy
(it was he at least who did, I believe), but to me the name of Phytoptosy seems
more appropriate from the moment that it has been proved not to be due to a
fungus (Zrinewn), as it was once thought, but to a mite (acarus), the Phytoptus.

t{ As the word gal/ could probably be only applied to pathological products
of more or less roundish form, Thomas, to whom we are indebted for most accurate
researches about this disease, proposed ultimately to designate by the Greek
word cecidium every abnormal formation (in which the plant takes part) of the plants,
caused by parasites; hence diptera-cecidium, acaro-cecidium, myco-cecidium, &e.,
according to whether the galls are due to diptera, acari, or fungi, &e. Besides
grouping in two large categories all these varieties, viz. those caused by attacks
of parasites with negative cones, and those due to attacks in other parts of the
plants, he called the first acrocecidii and the second pleurocecidii, and lastly
ceecidozoids the animals, cecidophyti the plants producing parasitism. Beitrige z,
Kennt. d. Milbg. n.d. Gallm. in Giebel’s Zeitsch. f. d. gesammten Naturwissen-
schaften, vol. xlii. p. 517.

182 The Phytoptus of the Vine. By Prof. Giovanni Briosi.

which, thus attacked, have not a single spot left healthy and
uncovered.

Convex on the upper and concave on the under side of the
leaves, these parasites present themselves covered with minute
hairs, whitish in spring, later on reddish, or of a more or less dark
tobacco colour.

Fig. 1 represents a vine leaf slightly diseased, seen from
beneath where the galls appear concave. :

On the upper side the galls retain in the beginning the green
colour of the leaf, turn yellowish later on, and become even brown,
according to the force of the disease or the variety of the vine.
Malpighi thought that the galls were caused by the drops of
a liquid which he saw deposited by insects on the leaves together
with eggs, and to which liquid he ascribed a fermenting action.
Afterwards Malpighi’s explanation did not seem satisfactory, and
many naturalists studied the phenomenon of the galls of the
plants, amongst whom Persoon, Fries, Réaumur, Unger, Schlech-
tendal, Fée, Lacaze-Duthiers, Vallot, Pagenstecher, &c.; and also,
in the past few years, Landois, Thomas, and Sorauer published
most important works on this subject.*

Most of them at first saw in the contents of the galls parasitic
fungi, and thus were created the genera Taphrina, Hrinewm, and
Phyllerium.

Palissot de Beauvais believed them algx, and Unger enlarge-
ments of the leaf cells; others, directly enlarged hairs.

* Publications —Malpighi, On the Excrescences and Tumours in Plants;
Persoon, Sinops fungor, 1809; Fries, Observat. mycolog. 1815; Idem, Syst.
mycologicum, 1825; Schlechtendal, Denkschrift der botan. Gesellsch. in Regens-
burg, t. ii. 1822; Idem, Botan. Zeitung, t. xxiv.; Réaumur, Mémoires pour servir
a 'Histoire des Insectes, 11. Mem. ix.; Vallot, Med. Acad. Dijon, 1832, part. d.
scienc.; Unger, Die Exantheme der Pflanzen, 1833; Duges, Annales des Sciences
naturelles, 2™¢ série, t. ii. 1834; Fée, Mémoire sur la Groupe des Phylleriées de
Fries, 1834; Lacaze-Duthiers, Recherches pour servir 4 Histoire des Galles,
Annales des Science. nat. 3° série, Bot. t. xix. 1853 ; Dujardin, Annales des Sciences
nat. 8° série, t. xv. 1857; A. Scheuter, Troschl’s Archiv fir Naturgeschichte,
Jahreang 23, t. i. p. 104, 1857; Pagenstecher, H. A., Ueber Milben, besonders
die Gattung Phytoptus, in Verhandl. d. nat.-med. Vereins zu Heidelberg, t. i.
1857-59 ; Landois, H., Eine Milbe (Phytoptus vitis mihi) als Ursache des Trau-
benmisswachses, in Zeitschrift fiir wissenschaftliche Zoologie von Siebold und
Kolliker, t. xiv. p. 353, and following ones, 1864; Landois and Roese, Bot. Zeit.
1866, No. 38, p. 293; Thomas, Fr., Ueber Phytoptus Duj. und seine grossere
Anzahl neuer und wenig gekannter Missbildungen, welche diese Milben an
Pflanzen hervorbringen, con. I. Tay. in Prog. d. Realschule zu Ohrdurf, 1869 ;
Idem, Schweizerische Milbengallen, Verhandlungen der St. Gallischen naturw.
Gesellschaft, 1870-71; Idem, Milbengallen und verwandte Pflanzenauswiichse,
in Bot. Zeit. 1872, No. 17, p. 282, and following ones; Idem, Entwicklungs-
geschichte zweier Phytoptus-Gallen an Prunus, in Giebel’s Zeitschr. f.d. ge-
sammten Naturwissenschaften, t. xxxix. p. 193, and following ones, 1872; Idem,
Beitriige zur Kenntniss der Milbengallen und der Gallmilben; Idem, Die
Stellung der Blattgallen an den Holzgewachsen und die Lebensweise von Phy-
toptus (Zeitschrift f.d. gesammt. Naturwiss. t. xlii. pp. 513-537, 1873) ; T. Moritz,
in Frauendorfer Blatter, p. 30, 1873; Sorauer, P., Handbuch der Pflanzenkrank-
heiten, Berlin, 1874, p. 165, and following ones,

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The Phytoptus of the Vine. By Prof. Giovanni Briosi. 183

At present, however, after the observations of Fée, and the
researches of Landois, Sorauer, Thomas, and others, it is ascer-
tained beyond doubt that these cecidia are due to the punctures
and irritation produced in the texture by the acarz, who lodge in
it and live on the leaves.

Cutting a very thin lamina across a gall of a vine leaf, and
placing it under the microscope, there presents itself, as nearly as
possible, a picture such as drawn in Fig. 14, viz. a forest of hairs
of various sizes and shapes, and between these minute animals with
elongated bodies, with four legs above, with small antenne, and
segments precisely as Fée saw them in 1833.*

These are mites (acar?), of which there has been formed a
species for itself, called Phytoptus, which name was given to them
in 1851 by Dujardin (who observed them on the linden and hazel),
in order to express that they are really and solely parasites of
living plants. These pathological plagues are thus produced.

When the animal has found a favourable spot in the leaf,
it pricks its texture, and sucks the moisture of the perforated
cells. The plant now remedies on its part these punctures and
prolonged irritation by supplying the wounded spot with fresh
nourishment ; hence an afilux of substance (which can be ascer-
tained under the microscope), and consequently an increase in the
wounded cell or cells, which in consequence swell and extend
externally and cause the formation of elevations. This process is
clearly shown in Fig. 14, where f, e, d, are cells in various stages
of such transformation.

The cells participating in this work are solely the epidermoid
cells. Professor Landois, of Heidelberg, to whom we are indebted
for the most important and complete work on the Phytoptus vitis,t
however, attributes these projections to the underlymg parenchy-
matic cells, and says that the epidermoid cells are never trans-
formed into projections (f), which is inexact.t

These hairs or projections can attain a length four or five times
the size of the leaf to which they belong; in fact, I found some
of 0°85mm., 0°90 mm. (the average diameter of which was
0:03 mm.), on a leaf which only had a thickness of 0°20 mm.
They are generally club-shaped, that is, are thicker towards the
upper end, especially when young ; they are more or less irregular,
often crooked or curved in various ways, presenting protuberances

* Feée attributed the formation of the galls “ to an elongated larva with four legs
terminating in little tufts of hair, attached to the upper and fore part of the body,
which has transverse rings, and is covered with hairs.” See Targioni Tozzetti, in the
Bulletin of the Entomological Society of Italy, 1870, p. 283, and following ones.

+ Summing up of Targioni in the Bulletin of the Italian Entomological
Society, 1870, p. 283.

t “ Die Epidermiszellen des Blattes wachsen nie zu Féden aus, sondern die Milbe
sticht mit thren stiletartigen Mandibeln durch die Oberhaut die Parenchymzellen des
Blattes an.’—Landois’ work, cited amongst the Publications,

184 The Phytoptus of the Vine. By Prof. Giovanni Briosi.

and angles. ‘They are unicellular, that is, not presenting divisions,
of which I at least saw none. Landois, on the contrary, found
them to be formed of a row of elongated cells, which, to my mind,
seems a mistake; and fig. 7 of his plate xxxi.* must probably
have been taken from a normal hair of the vine (just as one of the
hairs of my Fig. 14, which owing to a lithographic error in some
plates doesnot reach out of the parenchyma), and not one of those
pathological hairs of which we are speaking.

These hairs contain a granulated transparent protoplasm,
colourless or slightly yellowish when young, and more or less
opaque or yellowish-brown when old. ‘Towards their base there is
almost invariably found (toward the end of summer) an abundant
quantity of starch, in form of very fine granules, similar to that
gathered by me in the vessels of the higher plants.

Now and then (not always, as Landois says) I also found small -
crystals in the hairs, but not in the needle form of the raphides, so
abundant in almost all the normal textures of the vine.

These hair crystals are in such small quantity that it does not
bear out what Landois says of the great waste of tartrate of potash
caused by it. The same may be said of the chlorophyll, which I
found very rarely even in the young hairs, where, on the other
hand, he found it in abundance. Starch I found often abundant in
the primary parenchymic strata lying beneath the hairs, which
unusual accumulation of material in those cells is due to the
abnormal and extraordinary development of organic substance
required for the formation of the hairs. The texture of the parts
of the leaf corresponding with the galls (harder than the surround- .
ing healthy one) is seen more or less changed; the protoplasma of
the cells frequently lost its transparency and became dark, either
orange or brown. .

These changes extend frequently, with various interruptions,
throughout the thickness of the lamina up to the cellular stratum,
which is bordered off by the opposite side of the leaf (g, Fig. 14).

The plant loses, therefore, not only a considerable quantity of
plastic substance which produces the pathological texture, but also
organs which should produce this matter, grains of chlorophyll, of
which the cells, whose protoplasm changes, are full; and it is easily
understood that the harm done to the respiration organs must be
hardly less than that done at the same time to the assimilation ones.

The raising of the texture towards the upper side of the
leaf, that is, on the opposite one to the wounded spot, Thomas +

* Landois, Eine Milbe (Phytoptus vitis), &c., see Publications.

+ He says, verbatim: “ Der Intracellulardruck wird dadurch einseitig vermindert
werden und muss folglich eine Riichwirkung ausiiben. Der nicht compensirte Druck,
welchen der fliissige Zelleninhalt auf die der ausgesogenen Stelle diametral gegentiber-

liegende Wand ausiibt, bewirkt die Forthewegung der Zelle selbst und des thr im Wege
stehenden Theiles, der Blattspreite.’—Bot. Zeit. 1872, No. 17, p. 286.

The Phytoptus of the Vine. By Prof. Giovanni Briosi. 185

explains by a partial diminution of the intercellular pressure, in the
wounded and emptied cells, and Sorauer * by a hardening and
perhaps a cuticularization of the cells due to the action of the
atmosphere, which penetrates into the structure of the wounded
cells. Now, without wishing to set these causes entirely aside, I
think that the same forces which produce the hairs also cause this
phenomenon. In fact, the afflux of the substance which takes
place towards that spot of the leaf, where a gall begins to be
formed, must extend by endosmosis and exosmosis more or less
to all the strata of the texture lying in the thickness of the leaf,
thus offering to all the cells of the lamina in the region correspond-
ing with the wounded spot a more than usual nourishment. Whilst
therefore the cells of the under side of the leaf discharge so much
material, owing to the hair production, those underlying, up to the
epidermis growth of the upper side, participating in this increased
nourishment must of course grow and swell, which they (to my
mind at least) cannot do without producing an incurvement of the
lamina of the leaf, since the texture which compasses the gall in
its normal state cannot grow with the same force and rapidity on
account of the lesser nourishment.

We now come to the mite, or acarus, the cause of the disease,
This animal, belonging to the species Phytoptus Dujardin
(Phytoptus vitis, Landois), is invisible to the naked eye, and its
extreme smallness renders the study of the same, even with the
microscope, most difficult. This explains why, notwithstanding
the most painstaking researches of distinguished scientific men,
there is still some doubt about its formation. The body is long,
flexible, almost cylindrical, tapering off at the two extremitiés,
which are slightly inclined towards the belly (Figs. 2, 3, 11, 12).
In front it has two pairs of legs, which, when extended, project
a little (about 0°01 mm.) beyond the extremity of the head. It
is covered with transversal rings, which extend on one side to the
insertion of the hinder pair of legs, and on the other to within
a short distance of the anal opening. The cephalo-thoracic region
is smooth, viz. without rings, whilst a very small depression, which,
however, can always be distinctly recognized, separates it from
the abdominal region. Above, nothing distinguishes the head from
the thorax (which is common indeed to all arachnida, they having
a cephalo-thorax), one superficies continues on both the segments,
and the front part, which is turned down, terminates in a conical
trunk.

The proboscis communicating with the head is hollow, open in
front (Fig. 12, m), and behind terminating at the cesophagus
(Fig. 5, 2). On the abdominal side, that is, the one opposite to
the dorsal, this cavity opens longitudinally, and shows an almost

* Handbuch der Pflanzenkrankheiten, p. 171.

186 The Phytoptus of the Vine. By Prof. Giovanni Briosi.

triangular fissure ; the smaller and hindmost side is represented by
the under and triangular lip (Fig. 12, 2) of the mouth. © This
opening is not always open, as the animal can bring the lateral
sides so near as almost to touch one another, and also the sides of
the angle projecting from the lower lip (Fig. 3), thus forming a
tube which it uses for sucking, This cavity seems to enclose two
very small mandibles &, 7, lamellary, and terminating in a pointed
manner, which sometimes are placed on one another in such a
manner as almost to resemble a single point (Fig. 5). The animal
can draw in or lengthen these mandibles at pleasure (indeed they
are seen in various lengths, and sometimes not even the smallest
point of them projects or can be distinguished), and they can reach
up to the front end of the opening, and perhaps even beyond.
With these the mite must prick the leaves in order to suck the
juice afterwards with the cephalic or buccal extremity which is
transformed into a tube. The length of the thoracic region, from
the point where the rings end to the extremity of the head,
measured on the average 0°0265 mm., in animals whose whole
length was 0°09 mm., viz. about one quarter of the total length
of the body. ‘The development, however, of the curved upper or
dorsal line of the cephalo-thorax of the same animals, from the
spot where the dorsal bristles are inserted up to the top of the
head, was on the average 0°0306 mm.

‘The skin of the abdomen, as said before, is externally covered
with ring-like elevations, which are found flat and nearly level with
the axis of the body, and cease all of a sudden at a short distance
from the anal opening, leaving a small part of the belly (about
0-0085 mm.) perfectly smooth. I never counted more than seventy
rings, generally only from sixty to sixty-six; their size in already
developed animals varies from 0°00111 mm. to 0°0017 mm.
Sorauer in the Phytoptus piri found, however, from fifty to
eighty rings; and Landois in the Phytoptus vitis counted from
120 to 180, each measuring 0°0013mm. But as, according to
Landois, the average size of the longest (female) animals is
0°13 mm., with a diameter of 0°035mm., the numbers of the
rings must necessarily be a mistake, as otherwise the length of
that part of the body which is covered with rings would exceed that
of the whole body. Under great enlargement I observed that these
rings are not smooth or uniform, but that each of them result from
a series of raised corpuscles, just as Sorauer saw them in the
Phytoptus piri.

The anal opening is placed at the lower end, in the middle of a
kind of disk which is a little hollowed out, in which the body
terminates.

On the body I found six pairs of bristles, two on the dorsal
surface (one on the first, the other on the last ring), and four on

The Phytoptus of the Vine. By Prof. Giovanni Briost. 187

the belly. The first pair of the latter are placed between the ninth
and twelfth ring (counting from the side where the head is), the
second pair between the twentieth and twenty-second, the third
pair towards the thirty-eighth ring, and the last pair invariably at
the last but five rings. The hairs of the first dorsal pair are
generally upright, diverging, and turned down at the end. The
hairs of the last pair are nearly parallel with the axis of the body,
turned towards the anus, the shortest and the closest placed towards
one another (f, in Figs. 2,5). Landois, however, counts on the
belly only six or seven large bristles; and Sorauer on the Phytoptus
pert counts also six pairs, only slightly differently placed, as I
found them on the Phytoptus vitis.

The legs, colourless and nearly transparent, seem to be com-
posed of six joints; the first, by which the leg is inserted on the
thorax, corresponding with the coaa of insects, carries always a
long bristle (Fig. 18); the second, which is the longest and most
robust of all, shows two ring-like elevations, on the side of one of
them being attached a second bristle; then follow three rather
short divisions, the second last having a third bristle or hair
pointed forward, and of such length as almost to reach to the
extremity of the joint, which forms the fifth division, and on this is
_ Seen a kind of strong and pointed style in the centre, bearing five

appendixes or lateral bristles, so as nearly to resemble the form of
a feather. There is also a small cylinder (through a lithographic
error in the Plate ending in a point) bent forward and downward,
which covers, so to say, the feather or thorn, and seems to protect it.
The small cylinder is a little longer than the feather, and larger
(the average of three which were measured was 0° 0066 mm. length,
0-00085 mm. diameter). The length of the legs in animals whose
bodies measured on the average 0°90 mm. was 0°025 mm., and the
diameter 0: 00225 mm. at the coxa.

Neither description nor drawing given by Sorauer of the tarsus
of the Phytoptus pir correspond with those of the Phytoptus vitis
described in the foregoing, and also drawn by Landois, who, how-
ever, changes the small cylinder into a bristle. The legs are
compressed at the sides, and therefore if seen sideways appear
larger than seen in front.

Landois distinguishes in the legs three divisions only, but says
that there are in the middle one (corresponding to our second one)
two slight elevations, and in the third, two or three kind of loops
or ring-like indentures. I agree that the first ones may be simple
elevations, but the second ones appear to me true divisions of parts,
and because of them I count five, which added to the tarsus, form
therefore six parts or divisions for each leg.

The animal walks very quickly notwithstanding the distribution
of the moving organs, which is little suited to the shape of the

VOL. XVII. P

188 The Phytoptus of the Vine. By Prof. Giovanni Briosi.

body. It generally moves (raises or lowers) two legs at once, the
right fore leg and left hind leg, or wice versd, and sometimes (for
instance, when tired) it assists with its body, putting on the ground
the anal extremity, which seems to act as a venthole (ventosa). In
this case the body, bending semicircularly, shortens itself by draw-
ing in as a leech, and the anus, whilst now nearly approaching the
head, becomes fixed to the ground (or leaf), whilst the animal,
using it as a support, lengthens itself by advancing the fore part of
its body, and repeating the manceuvre.

This cecidozoid when walking seems to put on the ground
first the tarsus with its small cylinder, which, contrary to what
Sorauer assumes (who believes it to be immovable), appears to me
to be articulated and endowed with vertical motion, which allows
the animal to assume a quasi normal position in that part on
which the tarsus itself is inserted, and it is on this that the animal
supports itself. The feather-like process too is articulated, and
endowed with a lateral motion. The legs as well as the hind part
of the body must be furnished with, relatively speaking, very
strong muscles in order to allow of such a rapid motion.

Under the line of insertion of the second pair of legs at the
beginning of the abdomen, exactly after the second or third ring,
are the genital organs, which outwardly appear as a kind of valve
or sucker, whichever you may call it, smooth, attached to the skin
of the body, above, and free below, and terminating in a (circular)
arc-like curve.

This valve, sometimes shut, sometimes open, covers the genital
organs, hiding them almost always from the observer's eye. Once
only, out of thousands of observations, I happened to see under it
an oblong slit, around which ran a strong muscular ring, which
had the aspect of a vagina.

This detail has not been drawn, because the preparation was
spoiled ; however, it resembled nearly fig. 6 of Sorauer.*

In one pair of animals I saw in the region of the genital
organs a fissure turned upwards. Of the male organs I know
nothing whatever, outwardly the sexual organs present one and the
same form in all animals.

The male, however, appears to be smaller than the female, I
having several times found two animals closely stretched together
on their bellies, which I retained in state of copulation (in alcohol),
of which one invariably was smaller than the other. If, however,
one does not wish to take into account this difference in size, a
very uncertain distinction, since even amongst the small animals
there are some found with eggs, then I would presume to say that
the male cannot be distinguished from the female with certainty,

* Handbuch der Pflanzenkrankheiten, Tay. 1%, p. 122,

The Phytoptus of the Vine. By Prof. Giovanni Briosi. 189

unless pronouncing males all animals in which no eggs can be
discovered.

Sorauer, and before him Scheuten, found in the Phytoptus pore
animals of two distinct forms, that is, besides those cylindrical ones
described here, others larger in front and round like egg ‘tops
(Spitzeirunde), which were supposed to represent the male form in
complete development. On the vine, however, I never could see
any other but the variety of the cylindrical form, and Landois too
seems only to have found this one, as he does not speak of an
other. The animal of Figs. 11, 12 (laterally and in front), with
valve entirely shut, may be to my mind either male or female, in
which no eggs can be discovered.

Once I had the opportunity of observing very closely the
esophagus, the beginning of which is seen in n, Fig. 5; it is a
tube with a very thin coat, which, as it descends, is enlarged to a
kind of small bladder or bag, which is seen at the back part,
towards the dorsal (at the same height about as the genital organs),
which must take the place of the stomach. The intestines, how-
ever, are lost below the stomach, and sometimes only the last part,
ending at the anus, reappears.

In the abdominal region there are often found oval corpuscles
of various sizes, the largest in front, the smallest behind ; all con-
tained in an oblong tube or bag, which ends in the genital valve
on one side, and extends towards the anus on the other. The first
are eggs in various stages of development, the second the ovary.
The eggs are discharged by the opening of the valve (a, Figs. 2, 3),
and I believe I have caught an animal in the very act of ex-
pelling matured eggs, pretty far out already, as seen in Figs. 2, 3,
representing the said animal laterally and in front.

The ovary occupies the abdominal region, viz. nearer the
abdominal surface than the dorsal (contrary to the intestines), and
in the fore part, where the most developed eggs are, it seems to fill
up nearly all the internal cavity of the animal.

In the cecidozoid of Figs. 4, 5, the ovary was seen partly
hanging out of the body, which was torn from above. The eggs
when leaving the body are covered with a glutinous substance, on
account of which they adhere to the objects on which they fall.
Thus they are often found laterally suspended from the hairs C,
where the mother must have deposited them. The egg has a
somewhat elongated shape, and its contents when leaving the body
of the mother appear uniform and finely granulated (Fig. 6). As it
increases in volume one begins to distinguish in the interior a
centre line (Fig. 8), afterwards the roundish shape of the outline
of the embryo (Fig. 7); and even before breaking the vitelline
membrane one can perceive inside already the animal rolled up in

p 2

190 The Phytoptus of the Vine. By Prof. Giovanni Briosi.

itself, with the outlines of the head already sketched and distinct,
and with the traces of the rings on the body (Fig. 9). In Fig. 10
an animal is represented which scarcely left the vitelline mem-
brane a, to which it is still adhering (attached). In this stage no
hair could be seen as yet, neither were the legs all formed.

The smallest animals I found measured 0°045 mm., and there
I saw already the posterior dorsal hairs (which seem to be formed
first) and the small cylinders of the ¢ars¢. The largest animals I
found reached 0:1513 mm. in length, and between these two limits
I found every size.

I have said that this mite (acarus) has four legs only.
Landois, however, found under these well-developed legs, two
other rudimentary pairs. He relates that these acari, before
they have reached their complete development and are fit to
generate, pass through at least four changes: the first taking place
when they leave the egg and get the tarsus projections; in the
second they become simply larger; in the third they get the first
pair, and in the fourth the second pair of rudimentary legs. Thus,
he adds, the general rule, that all the acarzi when fully developed
possess four pairs of legs, is fully confirmed.* I believe that
Landois is mistaken; the four rudimentary legs, represented by
four small appendixes, each terminating with a bristle, I have
been unable to perceive. ‘There are, it is true, sometimes found
animals who might easily give rise to such an idea, because on the
spot where he puts the rudimentary legs there is an elevation
terminating in a bristle; but under close observation one sees
that this is due to the genital valve, which is found more or less
raised by the action of the body under it, which seems to prepare
itself for the expulsion of eggs. ‘Thus the bristles do not form part
of the raised appendixes, but are attached to the hairs of the body,
nearly at the margin of the genital aperture, as seen in Figs. 2
and 3, from which I conclude that these animals do really constitute
a special genus of acart, which have only four legs.

These arachnida seem to possess a most extraordinary tenacity
of life. Sorauer saw them moving the legs after being twenty, and
Landois after twenty-four hours in glycerine.t From the fact of
their being able to live so long in a liquid like glycerine, Landois
argues that their respiration is neither pulmonary nor tracheal,
that it cannot even be cutaneous, and concludes that they must
breathe through the anal opening.

These acart are found on the vine at whatever season of the
year it is examined, and Landois is in error when he affirms that
they all die at the first diminution of temperature, that the eggs
only remain between the hairs of the leaves, which fall in autumn,

* Kine Milbe als Urs. d. Traubenmiss, p. 357.
+ Frauendorfer Blatter, 1873, No. 30. (Sorauer.)

The Phytoptus of the Vine. By Prof. Giovanni Briosi. 191

eggs destined to produce in spring the young phytoptus, who climb
up upon the new vine shoots. In autumn, on the contrary, these
animals emigrate from the leaves, in order to nestle under the
bracts which cover the winter buds, and perhaps to the roots
where Moritz found them in the months of January and February,
and on which they would cause the same alterations similar to
those caused by the Phylloxera vastatriz. Between buds, gathered
in January (in the midst of the cylindrical and very long hairs
which are found under the scales or exterior bracts for the pro-
tection of the buds), I found a large number of these cecidozoids,
a little lethargic, but alive, and disposed to activity when exposed
to heat.

In one bud I counted more than 200 animals, in another 212,
in a third 112, and in a fourth 72, and I do not think I have seen
them all. Analogous observations have been made by Thomas *
on the buds of Pirus communis, Prunus domestica, Sorbus aucu-
paria, Tilia grandifolia, Alnus glutinosa, Acer campestre, &c. ;
and Sorauert found them alive between buds of trees which
shortly before had been exposed to a cold of —18° R.

At the first mild breezes in spring, and the swelling of the
buds, the animals regain breath, and begin again to lay eggs,
which they deposit direct on the young leaves of the developing
bud; thus the young ones are scarcely born, when they find
already within reach the food which nourishes them. With the
first young leaves of the vine, indeed, are discovered the first
galls under the form of small spots of a colour little different from
the parenchyma of the leaf, scarcely raised on the upper sides, and
which can be specially well discovered by examining the young
vine leaf by holding it between you and the sun.

The distribution of the galls on the plant is also regulated
by certain rules, which particularly depend on the conditions
of nourishment of the animal, that is to say, on the one hand, of
the faculty and force of the organs taking the nourishment, and
on the other, of the mode of production and development of
the latter. Thus it is that one can observe in May, on the
stems attacked by the Phytoptus (when the vines are in full
force of development), 1st, shoots which only present galls on
the original and exterior leaf of the bud, which produced the
branch and remained at its base; 2nd, shoots in which the galls,
besides on the base leaf, reappear along the branch in two or
three spots, leaving long intermediate spaces with perfectly un-
hurt leaves; 3rd, shoots at last, in which the galls have left unhurt
almost all the principal leaves, that is, those directly attached to

* Beitrage z. Kennt. d. Milbg. u, Gallm. Giebel’s Zeitschr., &c., vol. xlii,
p. 517, and following ones.
+ Hand. d, Pflanzky. p. 177.

192 The Phytoptus of the Vine. By Prof. Giovanni Briosi.

the branch, and are found instead on the small leaves of the lateral
small branches, growing out of the axils of the principal leaves,
besides on the extreme end-bud of the shoot itself. This proves
that the animal goes to lodge on the young textures which are
still growing, probably because when the leaves are fully developed,
their texture hardens so much, that the animal’s mandibles can
pierce it no longer.

And we owe probably to this circumstance, taken together with
the other that the development of the plant in spring particularly
seems to proceed more rapidly than the multiplication of the
animal, that the disease does not cause all the harm to the vine
which might be expected. In fact, we see that before the animal has
multiplied to such a degree as to have to emigrate, for instance, to a
lateral bud, the principal leaves of the stem are already developed
in such a manner and way as no longer to allow the animal to rest
thereon, and it leaves them, in fact, untouched, and goes higher up
in search of a new bud.

The invasion must be very strong if the plant cannot save
a good part of its leaves.

Thus, in fact, whilst in some vineyards in Favara the number
of stems attacked by the galls was very large, there were very few
in which the disease had spread to all the leaves. And where the
evil was compassed within a certain limit, the plant did not seem
to suffer much from it, whilst, however, on the stems which were
almost totally invaded, the damage was so serious as to check the
development of the fruit, the fruit buds having always remained
so small that they could not arrive at maturity. The fundamental
functions of the vine plant, as shown, that is, ass¢milation and
respiration, are disturbed, and the sad consequences can, of course,
not astonish us.

However, the assertion of Landois,* that this disease is not less
damaging to the vine than the renowned fungoid growth Ozdiwm
Tuckeri, Berk., appears to me exaggerated. Certainly, if in one
vineyard every year this disease should extend and augment in
intensity, the products would be not a little dimimished. However,
it is a fact in Italy (at least) where the disease is old, that (as far
as I know) there are few examples of excessive damage.

With regard to the remedies, Landois, assuming that at the
end of autumn the animals die, suggests collecting and burning
the leaves which fall in autumn and get dry under the plants,
which leaves harboured the eggs from which are produced the
animals in next spring; but after what has been said before, this
remedy is insufficient, and perhaps is not worth anything (in dry
leaves, gathered in December, I did not find any eggs, but only
husks and dead animals, deformed and shrivelled in every case),

* Memoir cited, p. 353.

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The Phytoptus of the Vine. By Prof. Giovanni Briosi. 193

since these cecidozoids not only do not die, but take their winter
quarters on the plant itself, and develop with it.

If the animals are in the buds, a large number will then be
taken away with the pruning, and therefore the stems which
showed the disease in the preceding summer should be kept as
short as possible, the cut twigs carefully gathered, carried away
out of the vineyard, and burnt. As to those portions of the
branch which remain on the stem, as the remaining buds cannot
be cut away under pain of almost losing the whole of the next
harvest, one should in spring, when the first shoots have reached
a certain length, and the galls have become apparent, cut off the
leaves which are attacked most, and also the top of the most
infested branches, carry them out of the vineyard, and throw all in
the fire. This operation should be undertaken during the sunny
hours, walking towards the sun, because the galls which at that
epoch are still very small and almost green, can be easier seen by
light which comes through the leaves. And this operation—easily
carried out in the majority of the vineyards, where the vine is low
and within reach of hand—repeated, conjointly with the short
pruning, for some time, would, in my opinion, in a few years result
in the destruction of this unwelcome visitor.

EXPLANATION OF PLATES CLXXVII. AND CLXXVIII,

Fic. 1.—A slightly attacked leaf seen from beneath.

Fies. 2, 3.—Phytoptus laterally and belly upward, with genital valve a raised,
and eggs b, which are about to emerge. (Enlargement 850 diameters.)

Fiaes. 4, 5.—Phytoptus same position as above, with eggs, and part of ovary m,
which projects out of the body torn above. (Enlargement 850 diameters.)

Fies. 6, 7, 8.—Eggs in various stages of development. (Hnlargement 850
diameters.)

Fig. 9.—An egg, much developed, which shows the embryo, with the traces
of rings and the appendages of the head and the legs already distinct. The
embryo detached itself from the vitelline membrane under repeated treatment
with solution of potash and acetic acid. (Enlargement 850 diameters.)

Fic. 10.—Phytoptus scarcely come out of the egg a. (Enlargement 850
diameters.)

Fas. 11, 12.—Phytoptus lateral and front views, with genital valve lowered
and shut, mandibles, &c. (Enlargement 850 diameters.)

Fic. 13.—A leg much enlarged.

Fic. 14.—Section across a gall, b; Phytoptus and eggs; f,e,d,A, hairs in
various stages of development.

Fic. 15.—Head of Phytoptus, seen across.

( aere9

IV.—On the Extrusion of the Seminal Products in Limpets.
By W. H. Datz, Smithsonian Institution, U.S.A.

In a paper published in the American Journal of Conchology,
Part 3, 1871, I brought together a summary of the various
details published from time to time by various naturalists, upon the
anatomy and physiology of this group. In that paper it was
shown that the manner in which the seminal products were freed
from the ovary and testis, and the passage by which they reached
the exterior, were unknown, and from the investigations of
Lankester and myself, that the existence of the oviduct figured
by Cuvier,* if not actually disproved, was at least a matter
of grave doubt, and had not been confirmed by any subsequent
examination. Lankestert had suggested that the passage of
the ova to the exterior was made through two orifices first de-
scribed by him and termed “capitopedal orifices.” These were
said to open, “one on each side of the head in the angle formed
by its junction with the muscular foot, and (internally) opening
into the blood sinus surrounding the pharyngeal viscera. He
also described an opening communicating between the “ peri-
cardium and the supra-anal articulated sac,’ or accessory renal
organ. The latter I have never been able to demonstrate to my
own satisfaction, but I do not assume to dispute its possible exist-
ence. Instead of opening externally in the angle formed by the
head and the foot, the “capitopedal orifices,” if I have correctly
identified them, are situated on the back of the neck, so to speak,
or more properly on the transverse portion of the integument above
the head and in front of the main pericardial chamber in the angle
formed by the neck and the inferior surface of the mantle over the
head. Mr. Lankester found them in Patella vulgata, but I have
never been able to detect them in the few alcoholic specimens of
that species which I have been able toexamine. In fresh specimens
of Acmexa patina and testudinalis, I have generally been able to
find them, and in the living animal they are of an orange colour.
In Ancistromesus Mezxicanus they are quite prominent in some
cases and almost imperceptible in others. They also differ in
character. In Ancistromesus (one of the Patellide), they appear as
true orifices, in the acmaas they present the appearance of an
elongate, narrow, glandular mass, from which, internally, a duct
is not always traceable. In some individuals they appear entirely
absent or abortive. My own opinion of their function is, that they
are aquiferous pores, such as are common to many mollusks,
through which water passes into the circulation directly in the

* “Mem. sur Jes Moll.’ 15, 1817. + ‘Ann. Mag. N. H.’ xx, p. 334, 1867.

Seminal Products in Limpets. By W. H. Dall. 195

Patellide and by a process of straining through the glandular mass
in the Acmeide. Whatever their office, it can hardly be of
fundamental importance, or they would not be so frequently found
in an abortive condition. Whether in some cases they may be
indirectly in communication with the renal sac is of little conse-
quence, as, in the paper alluded to, I have shown that in some
genera the pericardium is so situated that there can hardly be any
such communication, and in so homogeneous a group as the limpets
it is unlikely that such an anatomical character, if important,
should be inconstant.

Moreover, through the intricate channels alluded to, the ova
which are of considerable size could hardly be propelled without
some special muscular arrangement which does not seem to be
present in any case examined. Anxious to set at rest a question
of so much interest, and which for so many years had puzzled
anatomists, I have lost no opportunity of dissecting animals of this
group, especially the large species in which the characters might
be supposed to be more evident. The opacity of the shell and the
impossibility of getting at even the external orifices of the viscera
without destroying the life of the individual, proved effectual
obstacles to the study of these functions in the living animal.
While in the field, from 1871 to 1874 inclusive, I made dissections
of many hundreds of acmzeas with no definite result, except that of
finding that the sexual products appeared ripe in only a small
portion of the ovary at any one time, and in the acmeas the
portion most usually in that condition was the extreme right-hand
part of the anterior end, immediately below the floor of the larger
renal sac. No oviduct or opening was in any case demonstrated.

Somewhat discouraged by repeated failure, on leaving the field-
work in which I had been engaged, the matter was deferred until
a better opportunity should arise. Some time since, a large number
of specimens of the giant limpet of Central America, Ancistromesus
Mewicanus, were obtained by the Museum of Comparative Zoology
from the naturalists of the ‘Hassler’ expedition. By the courtesy
of Professor Alex. Agassiz a number of these were turned over to
me for dissection.

In this species the right supra-renal sac is quite large, covering
the entire superior surface of the animal between the muscular
attachments.. The viscera are coiled below it in the usual manner,
except that in ripe individuals the upper outer edge of the ovary
or testis extends rather more beyond the peripheral coil of the
intestine than in most species. A section then discloses the mem-
branes in the following order from above.

First, the external delicate layer of the mantle covering every-
thing else, and very intimately bound together by tough connective
tissue, with

196 Seminal Products in Limpets. By W. H. Dail.

Second, the superior wall of the right-hand (and only fully
developed) renal sac. By means of delicate, but tough columnar
walls of tissue, forming connected cellular cavities, overlaid with
semi-glandular tissue for the elimination of the renal secretions, the
upper wall of this sac is connected with,

_ Third, the floor of the sae, of similar constitution and tough-
ness. ‘The two are readily separated owing to the greater delicacy
of the connecting tissues, but the upper wall and the mantle, and the
lower wall and the tissues below it, are very intimately connected
by membranous fibres of such toughness as to render their separa-
tion without injury very difficult.

A muscular band or mesentery of considerable strength, having,
in the specimens of Ancistromesus examined, a width equal to
nearly one-twenty-fifth of its length; extends completely around
the internal viscera which are compactly bound together by similar
tissue.

From the floor of the renal sac similar but short mesenteric
bands extend downward to the peripheral band, radiating from the
apex of the shell, and having, when in their natural position, a
somewhat triangular form; the short sides of the triangles cor-
responding to the distal ends of the radii, and their plane surfaces
being nearly vertical to the horizontal plane of the visceral mass.
In the specimen under consideration there were one posterior and
ten lateral bands of this nature, five on each side. In details of
form and dimensions these vary in different individuals. They
widen at their junction with the tissues above and below, and send
off numerous fibres in all directions, and especially to the peripheral
band. We thus have as it were the entire visceral mass suspended
in the perivisceral cavity, free of the floor and sides of the latter
(except a delicate anchoring membrane, lying vertically in the
median line and connecting the median line of the visceral mass
with that of the muscles of the foot), but in contact or close con-
nection with its roof which is composed of the floor of the larger
renal sac. This sac opens externally by a prominent papilla to
the right of the anal papilla, while the smaller (and usually almost
abortive) left renal sac, opens by a proportionally smaller papilla to
the left of the anal.

The specimens were examined by cutting away the solid mus-
cular foot, and thus exposing the perivisceral cavity without in
any way lacerating its contents, sides, or upper surface. A number
of individuals were dissected without coming any nearer to the
object in view. At last, however, a specimen was taken up which
appeared to solve the difficulties and afford the long-sought-for
explanation. It wasa male. The surface of the viscera with one
exception was perfectly normal. On the right-hand posterior
portion of the periphery of the testis, covered with its usual delicate

Seminal Products in Limpets. By W. H. Dall. LOT

investing membrane, for the space of an inch from the posterior
end of the median line, forward, the ducts were swollen and
enlarged. They projected in a marked manner from the smooth
and evenly rounded normal surface, like “‘ varicose veins,” except
that the ducts are nearly parallel. In the ripest portions the
delicate investing membrane of the testis had become ruptured or
perforated, and the seminal matter exuding from these punctures
had been solidified by the alcohol in little rounded grains or
particles, which had not been disturbed by the careful manipulation
of dissection.

At those points where the congested or enlarged ducts were in
mechanical contact with the roof of the perivisceral cavity, that
is to say, the floor of the renal sac, numerous minute, but plainly
visible, oval perforations appeared. These were oblique to the
general plane of the membrane, the opening on the side adjacent
to the testis being usually directed somewhat backward instead of
vertically downward. They had also something of a funnel shape,
being larger on the side toward the testis, and some of them
were twice as large as others. The largest had a diameter of ‘015
inches, and would admit the passage of a fine bristle into the renal
sac. On applying slight pressure from above, the fluids contained
in the renal sac passed through in a minute jet. They were
irregularly distributed, corresponding in locality to the ripeness of
the ducts of the testis. Except where the testis in its ripe con-
dition was in immediate proximity or actual contact with the
membranes of the renal sac, no such orifices or pores were to be
found. In the other specimens in which the testis or ovary showed
none of these signs of maturity, no such orifices could be detected.
The membranes in such cases presented a smooth and practically
impervious surface in every part.

It would seem as if these facts gave a final solution to the diffi-
culty as follows:

When the ovary or testis is ready to discharge its products,
that portion of it which is ripe evinces its condition by an en-
largement of the ducts, continuing until dehiscence takes place.
Coincidently, the superincumbent membranes of the renal sac
(whether by sympathy with the congestion of the seminal organ
or otherwise) become lax and perforations make their appearance
immediately adjacent to the dehiscent ducts. Through these
orifices the seminal products make their way. A contraction of
the pedal muscles would be sufficient to cause the ejection. After
reaching the renal sac, the question of the extrusion of the ova or
semen presents no difficulties. ‘The same agency which empties
the sac of its secretions through the renal papilla would suffice to
eject the seminal products, which floating in the water would cause
the fertilization of the ova as in the case of Chiton.

198 Notes on “ Inclusions” in Gems, &e. By Isaae Lea.

The rarity of individuals in a ripe condition in collections may
be due to their repairing below tide marks at such times, and
hence avoiding the collector.

The method above suggested is paralleled in numerous other in-
vertebrates, and even some fishes, with non-essential differences of
detail. ‘The specimen referred to has been submitted to several
naturalists who agree as to the facts.

While additional evidence is desirable in corroboration, I feel
tolerably confident of the correctness of the inferences drawn from
the above facts, which furnish an explanation at once simple and
in accordance with experience in other cases, of a very puzzling
question.

I may add, that the localized turgidity or swelling of the ripe
seminal ducts had been previously observed by me on other occa-
sions among specimens of Acmxa patina; but having dissected
them in most cases from above, removing the membranes not con-
nected by tissue with the ovary, and looking more particularly for
a permanent duct or passage, the perforations of the renal mem-
branes were likely to, and did, entirely escape my notice.—Proceed-
ings of the Academy of Natural Sciences of Philadelphia.

V.—Notes on “ Inclusions” in Gems, &e. By Isaac Lua, LL.D.

In a communication on microscopic crystals contained in gems,
which the Academy of Sciences of Philadelphia did me the favour
to publish in its ‘ Proceedings’ * a few years since, I gave some
figures of these crystals, which I have frequently since verified. I
then observed that, beside these intercrystalline forms, there were
in most gems cavities frequently so numerous that they amounted
to tens of thousands.

Since the period of the publication of my paper, I have made
very large additions to my cabinet of gems, and particularly those
of the Corundum group, sapphires, rubies, and the so-called
Oriental topaz, Oriental amethyst, Asteria, &c. In the numerous
fine blue sapphires of my collection, I have rarely explored one
without finding numerous cavities, and ordinarily also finding the
beautiful microscopic acicular crystals, which, when the specimen is
cut cabochon, cause the three bands, and these by crossing form the
star in Asteria. The cuneate microscopic crystals are also quite
common.

Cavities, with or without the fluids, are so frequent in crystals,
from the soft calcite to the hard corundum, that little may be said
as to their occurrence, as they are so common.

* February and May 1869.

Notes on “ Inclusions” in Gems, &e. By Isaac Lea, 199

Cavities in quartz crystals enclosing fluids have been observed
by the older mineralogists, but the kind of fluid, and gas or air,
was not ascertained by them. Sir Humphry Davy, in 1822,*
investigated the contents of these cavities, and found them generally
pure water. The gas-bubbles were sometimes found to be “ azote.”
Sir David Brewster, in 1823, + published a memoir of great research
and value. He first had his attention called to the examination of
fluid in cavities by the explosion of a crystal of topaz when heating
it. He found cavities and air-bubbles in nearly twenty different
substances, and these inclusions were carefully examined by him.
In some of these cavities he observed two fluids { and crystals, and
these are figured in his plates. Subsequently, Mr. Sorby pub-
lished a long and admirable paper § on fluid cavities and crystals
in minerals, with numerous and interesting figures. He con-
sidered that the cubic crystals were probably chloride of sodium.
In his investigation he proved, by forming artificial crystals, that,
in a natural state, the fluid cavities, with their “ inclusions,” must
have been formed by aqueo-igneous forces. He gives a figure of
fluid in mica, but I have never seen any in that mineral, although
many hundreds have passed under my microscope in looking after
crystals of magnetite, &c. Mr. Sorby also published a paper on
cavities in quartz in the ‘ Phil. Mag.’ vol. xv. p. 158; also with
Mr. Butler in ‘ Proc. Roy. Soc. London,’ vol. xvu. p. 299. Kirkel
on “ Microscopic Minerals,” Neues Jahrbuch, 1870, p. 80, mentions
bubbles and cubic crystals in quartz. He found iron glance and
fluid in Eleeolite = Nephelite. In emery, from Naxos, he found
fluid in cavities.

In 1872, || Mr. Sang published an account of water in cavities
of calcite.

Very recently, Professor Hartley, King’s College, London, has
published a very able paper on the subject of the fluid in
quartz, &c.4] He says that Simmler in 1858, offering an inter-
pretation of Brewster's observations, concluded that the expansible
liquid was carbon dioxide. Professor Hartley states that in many
cases the liquid in quartz is water, but that in some cases he found
the two fluids; and his very satisfactory and careful experiments
show conclusively that the most volatile of the two fluids is car-
bonic dioxide. He found in every experiment that the fiuid dis-
appeared when exposed to 31° C., and reappeared on cooling.
Professor Hartley accords with Mr. Sorby in his reasoning that

* ¢Phil. Trans.’ 1822.

+ ‘Trans. Roy. Soc. Edin.’ 1823.

$ These two fluids Professor Dana without any analysis has called Brewster-
linite and Cryptolinite.

§ ‘Journ. Geol. Soe.’ vol. xiv., 1858, “‘ Micro-structure of Crystals,”

|| ‘ Proc. Roy. Soc. Edin.’ p. 126.

q ‘Journ, of the Chem, Soc. London,’ February 1876.

200 Notes on “ Inclusions” in Gems, &e. By Isaae Lea.

“at the time of its assuming the solid state, the solution endured a
high temperature.”

Calcite has been found to contain nearly a quart of this fluid,*
but it is not as common to be found in small cavities as it is in
quartz.

Fluorite.—Cavities in this mineral are rarely found, but they
are sometimes seen with fluid and air-bubbles.

Apatite.—I have never observed cavities in this mineral, but I
have not given it much attention in microscopic examinations.

Feldspar Growp.—In a former papert I gave the result of the
examination of many specimens of various species. Since then I
have examined numerous specimens of Labradorite, and found no
cavities, but the black crystals were very numerous. In the moon-
stone of this country I have not observed cavities or crystals; but
in two specimens, out of about one hundred from Ceylon, I have
seen a series of very regular quadrate cavities or crystals which do
not appear to have any fluid.

Tourmaline-—This interesting mineral is found beautifully
crystallized, and of almost all colours, white, brown, green, red,
black, &c. The finest are found at Mount Mica, near Paris,
Maine.t Some of these specimens have small internal elongate
crystals, which are terminated. A red specimen (Rubellite) in my
collection has many irregular cavities. One green one from Ceylon
has cavities with fluid, and another has very minute black acicular
crystals in one direction. In brown crystals from Lower Dianburg,
Carinthia, there are rough objects in the interior, evidently another
mineral enclosed, which do not require the microscope to detect
them.

Cyanite.—Of the white and the blue varieties I have not ob-
served any well-defined cavities or crystals; but in the grey-bladed
cyanite, found at Cope’s Mills, near West Chester, Pennsylvania,
there are always, I believe, small black masses which do not take
a regular form, but are usually elongate. These may easily be
detected by splitting a crystal along its eminent cleavage, and
examining the cleavage face with a lens of small power; but a
higher power is preferable.

Quartz takes upon itself many colours. In it are found cavities
in very great numbers, particularly in the clear fine crystals.
Those which exist in such an abundance in Herkimer County, New
York, and which are so limpid, and finely and doubly terminated,
are sometimes furnished with thousands of cavities, even in small
specimens, and these are of many various forms, frequently con-

* Specimen in the collection of the late Dr. Chilton, of New York.

+ ‘Proc. Acad. Nat. Sci.’ May 11, 1869.

} Dr. Hamlin has published a beautiful little work on the Tourmaline, with
illustrations,

Notes on “ Inclusions” in Gems, &c. By Isaae Lea. 201

taining fluid. In some cases the fluid may be seen to move by the
unaided eye. In these Herkimer crystals, carbon in the form of
anthracite is of very common occurrence, and in one of my speci-
mens a small portion moves in the fluid of a cavity. These cavities
often exist in an entire sheet, almost across the prism of a crystal. *
In smoky quartz these cavities are much rarer, as also in
~ amethyst and wine-colour and green quartz. The amethyst is
frequently penetrated with crystals of rutile, and these are often
very large, sometimes one to four inches long. The Chester
County specimens usually have numerous curved filamentous crys-
tals, easily detected with a common lens. In Way’s Feldspar
Quarry, near Dixon’s, Delaware, there is a very peculiar form of
quartz, which is nearly transparent, but somewhat clouded. The
fragments of all sizes, from that of a pin’s head to that of a small
walnut, are enclosed in a mass of Deweylite. These fractured
pieces are of indefinite forms. They are evidently cryptocrystal-
line, and look as if they may have been heated and suddenly
cooled, and thus fractured. When these pieces are subjected to a
high power, there may be detected in them very minute oval
cavities in great numbers, and the major axes usually placed in one
direction I have never seen cavities in milky quartz or blue
quartz. Sir David Brewster found many cavities in rock crystal
from Quebec with “ water and mineral oil.” t

Topaz.—tIn the various beautiful crystals which this mineral
presents, there are frequently found cavities with fluid, and some-
times in this fluid may be seen the cuboid crystals described by
Sir David Brewster. He found a single fiuid in some cavities, and
in others two fluids with “air-bubbles.” He says the fluid does not
expand with heat. The Saxony transparent white crystals some-
times have cavities, as well as those of pale wine-colour. The Bra-
zilian gold-yellow specimens have these cavities very frequently.
The clear pinkish are more free from them. I have never observed
any microscopic acicular crystals in topaz.

Emerald, Aquamarine, and Beryl—constitutionally the same—
differ very much in regard to their possession of cavities and their
commercial value. So far as I have been able to examine fine
specimens of emerald, it is rare to see one without cavities. One
which I have, of very fine colour, has many cavities of various
forms, in which are included a fluid enveloping generally two per-
fect cubic crystals of an unknown mineral. In all cases in this
specimen, the second crystal is much the smaller.

In aquamarine, cavities are not frequent, and in beryl I have

* Sorby, ‘Journ. Geol. Soc.’ 1858, found many cavities, and thinks that the
cubic crystals enclosed are probably chloride of sodium, as mentioned above.

+ The smoky quartz of Pike’s Peak has hexagonal spangles, which may be

mica.
t ‘ Trans. Roy. Soc. Edin.’ vol. x.

202 Notes on “ Inclusions” in Gems, &c. By Isaae Lea.

detected them only in a specimen from Unionville, Penn. In
this there is a biangular cavity with a small cubic crystal at
an inner angle. Throughout the mass there are small suboval
cavities.

Garnet.—As a precious stone this is by no means rare, but it
is lustrous, and of a fine colour. Cavities and microscopic crystals
are very common in this gem.* The cavities are usually irregular
and rough, and never to my knowledge have fiuid. On a polished
surface of a piece of garnet from North Carolina, nearly an inch
long, the reflexion of these crystals covered the whole surface with
prismatic colours.

Cinnamon Stone.—This beautiful variety of garnet, from
Ceylon, as far as I have been able to observe it, and I have some
twenty cut specimens, and numerous rolled pieces, has irregular
cavities and some crystals, as I have stated in a former paper.

Zircon.— With its high refractory power, this is used frequently
as a gem, and sometimes sold as a diamond when white and per-
fectly transparent. One of the numerous specimens which I have
examined has cavities t and microscopic crystals, and a specimen
from Ceylon has remarkable dark brown, elongate, fusiform spots,
with numerous dotted ones intervening.

Chrysoberyl.—The few specimens I have of this beautiful gem
have neither cavities nor microscopic crystals, but Brewster ob-
served “strata of cavities and both the fluids.”

Chrysolite = Olivine.—In some of my specimens I have
observed small cavities with fluid. Brewster met with them con-
taining “ fluid and bubbles of air.”

Spinel.—This gem occurs of several colours. The Spinel ruby,
so called, sometimes is very close in colour to the true ruby, but it
has not by any means the depth nor brilliancy of the true ruby.
In a pale-green specimen of great beauty which I have received
recently from Ceylon, I have not been able to detect cavities or
crystals. In my former papers I have expressed uncertainty in
this matter.f

Jolite—This gem is inferior in hardness, colour, and specific
gravity to sapphire, but is valued for its peculiar change of colour,
being dichroic. One of my specimens is without any inclusions.
The other is filled with blue four-sided prismatic crystals, which are
long, and enclosed in a nearly white subtransparent mass, These
erystals are sometimes broken and their parts prolonged in the
mass, and they are all lying in nearly the same direction.

Turquoise, with its peculiar and agreeable blue, is never trans-
parent, and neither cavities nor microscopic crystals are found in it,

* ¢Proc. Acad. Nat. Sci.” February and May 1869.
+ In a specimen in Dr. Leidy’s fine cabinet there are anastomosing cavities.
+ ‘Proc. Acad. Nat. Sci.’ February and May 1869,

Notes on “ Inelusions” in Gems, &e. By Isaac Lea. 203

Opal.—This exquisite gem, which displays such brilliant colours,
is very highly valued. It is but little harder than glass, and is
indeed considered as volcanic glass. Its remarkable flashes of
colour are attributed to fissures, in accordance with the theory of
Newton’s coloured rings. I have never been able to detect either
cavities or minute crystals in this beautiful gem, except in two
cases. One of my specimens has a brown, terminated crystal, a
six-sided prism of an unknown substance, about one-fifth of an
inch long, and terminated by a single oblique plane; the other has
several smaller ones.

Lapis-lazuwli.—This was used by the ancients as a favourite gem,
but it 1s not now valued as such. I have not been able to detect
cavities or minute crystals in any specimen in my possession.

Corundum.—This very interesting mineral, when in perfect
transparent crystals, is highly valued as a gem, under the name
of sapphire, ruby, &c., according to colour. When yellow, it is
called Oriental topaz; when purple, Oriental amethyst. When
purely white it is sometimes sold as a diamond. In this country
we have two localities only of corundum where any large quantity
has been found, that of Chester County, Pennsylvania, and Frank-
lin County, North Carolina. From the mines in Chester County,
several hundred tons have been taken, but no transparent crystals.
Some opaque ones are bluish and some pinkish. The North
Carolina locality has produced some very large crystals, and nu-
merous small ones. Of the latter there have been found many
quite pure and transparent, and these are sometimes blue and
sometimes red. But none of them yet found are of value as
gems. The fine sapphires and rubies are chiefly from Ceylon,
and they form some of the most beautiful objects in nature. I
have many of these in the form of worn pebbles, and some in fine
hexagonal form, as well as hundreds of cut specimens. I have
examined carefully more than one thousand specimens, with a
view to discover whatever “ inclusions” they might possess. In
a communication to the Academy* I described and figured some
microscopic crystals in these and other gems. Since then I have
added a very large number to my collection, and among these
several hundred large and small transparent crystals. In a careful
microscopic examination of these, I found a large number which
contain cavities and minute crystals, the former sometimes scat-
tered irregularly through the mass, and sometimes forming a
sheet or film. These cavities are of all forms, but usually sub-
elliptical ; sometimes tubular, and these tubes frequently anasto-
mose in a very beautiful manner. ‘These cavities are so numerous
that they frequently give a cloudiness to the specimen, which is
less valuable as a gem, but most interesting in a scientific point of

* «Proc, Acad. Nat. Sci.’ 1869,
VOL. XVII. Q

204 Notes on “ Inclusions” in Gems, &e. By Isaac Lea.

view. In some specimens these cavities exist by tens of thousands,
and Sir David Brewster stated that in a specimen under his obser-
vation there were about 37,000 of these cavities. I am sure that
in one of my large cut specimens there must be more than double
that number. It is a very common thing to see hundreds at a
time of these cavities in the Ceylon specimens, partly filled with
the fluids previously alluded to in these notes. But it is quite
rare that they are found in the specimens from North Carolina.
Still I have seen them in the transparent small fragments of deep
blue crystals, and sometimes in the transparent light-coloured
ones. In one specimen of the latter I discovered some most in-
teresting cavities, which contained, beside the fluid, each a single
cubic crystal. I had never observed an included crystal in any
eavity in the numerous Ceylon specimens which I have examined.
These cubic crystals have the exact form and appearance of those
in the emerald described herein.

In regard to the microscopic crystals in sapphire, having
described and figured them in the papers before alluded to, I have
little to add now. Further observation has confirmed what I then
stated regarding the radii of Asteria. Very recently I have
received a number of these Asteria of various colours, blue, purple,
white, red, and dove colour ; several three-quarters of an imch in
diameter. ‘The red and purple specimens are of peculiar beauty,
and when examined in the sun, or any strong light, they both
exhibit the microscopic acicular crystals with peculiar beauty, dis-
played as they are in hexagonal form, and reflecting the spectral
colours. The ruby Asteria is certainly among the most beautiful

objects in nature, and the purple are very little less so.

In some crystals of corundum there is a strong bronze reflexion,
and this is the case with some of the large hexagonal crystals which
were imported by Mr. 8. 8. White from India for commercial pur-
poses, and which he distributed with so much liberality to our
mineralogists. These bronze crystals have also been found at the
Black Horse and Village Green localities in Delaware County,
Pennsylvania. When examined with a good power, these bronze
reflexions are at once seen to be caused by minute acicular crystals,
and these may sometimes be seen in bunches.

A pale ruby, “ Rubicelle,” which I lately received from my
friend Hugh Nevill, Esq., Ceylon, about three carats, is a most
interesting and beautiful gem. It has the depth and brilliancy
almost of the diamond. It is nearly of a rose colour, and is per-
fectly transparent. It is cut with a top table and not entirely
symmetrical. Its refractive power is unusually great. Yet when
this brilliant transparent gem is examined with a high power and
strong light, the whole mass may be seen to be filled with long
acicular crystals in three directions, parallel to the prismatic

A Mode of altering the Focus of a Microscope. By M.Govi. 205

planes, and interspersed are numbers of very minute and delicate
cuneiform crystals.* It has also a small cloud of exceedingly
small cavities.

Another remarkable specimen may be mentioned here, which
has small cavities and minute microscopic crystals. It is of a pale
yellow or straw colour, and of a depth and brilliancy scarcely
exceeded by the diamond.

During the examination, about two years since, of some hun-
dreds of small crystals of sapphire, perfectly transparent to dark
blue, I discovered one which had very singular plumose impressions
on the planes of the prism. This induced me to examine carefully
all those which I subsequently procured, and I have now over
a dozen specimens which exhibit this very singular character. I
am entirely at a loss to discover the cause of this form of minute
impressions on so hard a substance. It evidently has been formed
by some collateral mineral substance, against which the molecules
in crystallization have been arranged.

Diamond.—The hardest of all substances stands first among
gems. It has not, however, much interest to the microscopist, as
no cavities with fluid have been, so far as known, observed; nor
has it included crystals of foreign substances. They are often very
imperfect, containing rifts and discolorations. Some of my speci-
mens have beautiful triangular impressions on the surface of the
planes. My friend Dr. Hamlin, of Bangor, Maine, is engaged on
an extended work on the diamond. Such a work is much needed,
and I know no one as capable as he to accomplish it. This gem
sometimes occurs of various colours. In my cabinet I have six
different colours.—Proceedings of the Academy of Natural
Sciences, Philadelphia,

VI—A Mode of altering the Focus of a Microscope without
altering the Position of either the Objective or the Object.

By M. Govt.

In working with the microscope, above all when we utilize it for
comparing measures of length, it often happens that after having
focussed it upon the first object, it is necessary to apply it to the
observation of a second one, which is not absolutely at the same
distance from the objective as the first. Then it becomes necessary
to alter the focus of the instrument in order to have a clear image
of the object, and this is done either by a movement of the whole
microscope (i. e. the tube), or by an alteration of the eye-piece or the
objective, or by a movement forwards or backwards of an inter-
* Proc. Acad, Nat. Sci” May 11, 1869.
Q 2

206 A Mode of altering the Focus of a Microscope. By M. Govi.

mediate lens (as in the parfocal meroscope of Porro). In all these
cases, no matter how much care may have been taken in the con-
struction of the apparatus necessary for these alterations, it is
almost impossible to avoid very slight deviations of the optical axis
of the microscope, and hence we cannot count on the perfect exacti-
tude of comparisons which demand an absolute invariability of the
direction of this same axis. If instead of changing the focus by
means of altering the optical apparatus we obtain the alteration
by elevating or depressing the object itself, it may happen, and it
does occur often enough, that the masses to be displaced being con-
siderable, the displacements occur irregularly by a series of jerks,
with flexion of the object, and hence with an uncertainty or an
alteration of the length to be measured. Moreover, one can hardly
focus one of the extremities of a scale without at the same time
altering the focus of the other end, which causes a loss of time, and
prolongs beyond measure operations which ought to be rapidly
performed.

It was therefore desired to find a means of altermg promptly
the vertical focus of the microscope within certain limits, without
having to fear either a change of direction of the optical axis of the
instrument or any alteration whatever in the length to be measured.
It was then necessary to consider how this could be done without
interfering either with the optical part of the instrument or with
the object. And it seemed almost impossible.

But on reflecting, it appeared that the interposition between
objective and object of a medium more refractive than air, bounded
by plane and parallel faces normal with the axis of the microscope,
would affect the object. Thus there is an apparent raising of
the object :

where d is the amount of elevation produced, e the thickness of the
medium introduced, and n its index of refraction compared either
with the air or a vacuum.

It will suffice in fact to place beneath the objective a plate with
plane and parallel surfaces, and of variable thickness, to bring
readily into the focal plane of the eye-piece the image of objects
situated at different distances in front of the object-glass without
altering the position of either the objective or the object. But it
was, if not impossible, at least extremely difficult to obtain solid
plates with plane and parallel faces and with a thickness which
could be altered at will, which withal were perfectly homogeneous
throughout, and maintained their perpendicularity in their initial
inclination in relation to the optical axis of the microscope.

Fortunately a well-known property of liquids—that of leaving
their surface during equilibrium perfectly horizontal—permits us

A Mode of altering the Focus of a Microscope. By M. Govi. 207

to obtain with them what we could hardly hope to get with solids.
Hence it is only necessary to employ a liquid layer placed, in a
sort of cup with a transparent bottom, beneath the objective. or
here we have a refractive plate whose thickness we can increase or
diminish, and whose surfaces keep up constantly the same relation
with each other and with the optical axis of the microscope.

If then one establishes between the objective and the object
a reservoir sufficiently large (in order to avoid capillary attrac-
tion), closed below by a plate of glass with horizontal surfaces
sufficiently parallel, and if then one introduces a liquid of the index
m, which one may vary the level of at will by aid ofa plongewr, or
by means of a communicating vessel filled with the same liquid,
one may always by variations in the weight of the refractive layer
bring to the same vertical distance objects whose real distances
differ by quantities more or less considerable. The limit of these
accommodations is given by the value of d, calculated from the
formula already given. And as one hardly has recourse to liquids
whose index of refraction is less than 1+3335 or more than 2°000
this limit would always be comprised between about a quarter and
a half of the maaimum thickness of the liquid contained in the cup.

It must be understood that it is not requisite to take account,
in this valuation of d, of the constant displacement produced by the
layer of glass and by a layer of liquid which it is well to have
above it in order that the variations of thickness may take place in
the same refractive substance.

In cases where the objects to be observed are directly plunged
in a liquid, this liquid might be made to serve the focalization of
their images.

The extreme mobility of most liquids demands great steadiness
in the “cup” which carries them; without this the agitation of
their surfaces would prevent the proper formation of images, just as
it not unfrequently happens in the mercury baths that are used for
astronomical purposes. If there are no trepidations, the observation
of transparent or opaque objects is conducted as easily through the
liquid layers as through the air, and the loss of light which results
from successive reflexions does not materially affect the clearness of
the images.

A slight defect of parallelism between the inferior surface of
the “cup” and the upper surface of the liquid should not affect the
exactitude of the focus, whilst perfect horizontality of this latter
gives this slight defect a constant value, whatever be the thickness
of the liquid layer interposed. It produces only in this case a
slight lateral displacement of the images, which, being the same for
all, alters in nothing the value of their relative distances.—A Paper
read before the French Academy, February 19, 1877.

( 208 )

PROGRESS OF MICROSCOPICAL SCIENCE.

The Structure of the Echinoids,—It seems that M. 8. Lovén has
published at Stockholm an essay on the above subject, which is of
some importance. It is illustrated by fifty-three plates, and is likely
to be of interest not only to the naturalist, but also to the paleon-
tologist. The ‘ American Naturalist’ (February) says that it is chiefly
zoological in its character, the text and plates are mostly devoted to a
discussion of the homologies of the shell of the sea-urchins, parti-
cularly those forms related to extinct genera of Echinoids. Com-
parisons are also instituted with the classes of Asteroids (star-fish)
and Crinoids, which will, if we mistake not, be found of much use
to paleontologists. Especial attention is devoted to certain organs
called Spherides, grouped around the mouth of sea-urchins, for the
discovery of which naturalists are indebted to Professor Lovén.
But the most interesting portions of the work are the exquisite
drawings illustrating the anatomy and distribution of the nervous
system and the water system of vessels. We have here for the first
time, clearly shown, the more intimate relations of these organs. The
plates are abundant and beautifully executed, the lithographs rivalling
in clearness and delicacy the best steel engravings.

The Position of Sponges.—Professor A. Hyatt, who lately read a
paper on this subject before the Boston Society of Natural History,
stated that he considered they formed the type of a new sub-kingdom
of animals. He treated at some length on their mode of development.
The paper will be published in the Society’s ‘ Transactions.’

The Oscillatoria and Bacteria formed the subject of a recent paper
before the Boston Natural History Society, by Professor W. G. Farlow.

Development of Scleroderma verrucosum.—In the ‘Annales des
Sciences’ (1876, p. 30) an important memoir is published on the
above subject by M. N. Sorokine, which is thus well abstracted by
the ‘Journal of Botany’ (January). It says that attention is first
directed to the two states, thread-like and lash-like, of the mycelium,
upon which no organs of fecundation were discovered. In a very
early state the mycelium consists of a cushion of short interlaced
dichotomous filaments, which afterwards become still more interlaced,
so that it has somewhat of a spongy structure consisting of masses of
interlacing fibres with frequent cavities. Fine branches are now given
off from the filaments which direct themselves into the nearest cavity,
and when there bifurcate at their extremity, one of the bifurcations
twining round its fellow; this is the commencement of the hymenium,
which increases quickly by the formation of other filaments from the
original one, and the young plantule now consists of a great number
of hymenial masses contained in a darker-coloured common envelope,
the intervals between the former being occupied by filaments which
give origin to the capillitium. The filaments of the capillitium become
transversely partitioned, and some of the segments are thickened, while

PROGRESS OF MICROSGOPICAL SCIENCE. 209

others remain thin and transparent, and during the time the spores
are ripening the latter are converted into mucilage, the simple or
branched thickened segments remaining. The origin of the basidia
is as follows: Immediately after the development of the hymenial
masses, some of the filaments of which they are composed bear
branches which direct themselves towards the centre of the mass;
these branches divide transversely, and the terminal cell becomes
elongated and is soon seen to carry four round pedicellate spores, the
nucleus of the basidium disappearing before the spores make their
appearance, as Woronine has already observed in Exobasidium.
M. Sorokine cannot share the opinion of Berkeley and Tulasne that
the spores do not arrive at their full development while attached to
the basidia, but that they fall off and draw elements of nutrition
from the nidus in which, when free, they find themselves. On the
contrary, he thinks that the spores do not fall until their development
is complete. He believes also that, contrary to what has already been
held, there is no regularity in the order of local maturation of the
hymenial masses. ‘I'he so-called “nucleus” of the spores is shown to
be of oleaginous nature, since it dissolves in alcohol.

Haperimental Observations on Mosses.—Some experiments of a very
interesting nature were conducted lately at Strasburg in regard to the
“artificial production of a protonema on the sporogonium of Mosses,”
by Professor Dr. Stahl. They are described at some length in the
‘Journal of Botany’ for January, by a writer who signs himself
G. R. M. M. He says, among other things, that as Brefeld’s views on
the alternation of generations of the Ascomycetes take the relations
existing in Vascular Cryptogams as a point of departure, it was first
of all the question whether the production of the sexual generation
was necessarily bound up with the formation of spores, or whether
perhaps, under normal conditions, other parts of the spore-bearing
plant were not in a position to produce the sexual plant. To settle
this question by experiment no better object could be found than the
sporogonium of Mosses, and after much searching Dr. Stahl found —
that of Ceratodon purpureus to be the most suitable for conducting
the necessary investigations. The experiments were instituted thus.
The sporogonia were partly extracted from their mother-plants—a
process which can usually be effected without injury—and partly cut
off directly above the point of their connection; all were placed on
damp earth under a bell-jar, and exposed to diffused daylight. Nota
few soon showed clear signs of decay; others again remained green
and unaltered in shape, with the exception of some deformations of
the capsule. After two or three months, however, dense protonema-
formations, on which leaf-bearing Moss-plants were already formed,
proceeding from the cut surface of the seta, extended over the earthy
substratum. From microscopic examination it appeared that the
protonema-threads owed their origin to the chlorophyll-containing
cells within the seta, longitudinal sections of which showed the way
they arise. After a lapse of three months the contents of most of the
seta-cells had died in both the forms of cultivation, but here and
there were found, extending along the whole length of the seta,

210 PROGRESS OF MICROSCOPICAL SCIENCE.

between the dead thin-walled cells of the fundamental tissue, cells
which not only retained their protoplasm and chlorophyll, but had
increased the volume of the latter in particular in a striking degree.
These occurred in the decayed tissue, sometimes isolated and some-
times in groups, the individual cells arranged beside or above each
other. Even from cells in the wall of the capsule Dr. Stahl found
protonema filaments to proceed. From Pringsheim’s observations, as
well as from those here communicated, the conclusion is clearly
arrived at that the transition from the spore-bearing generation to
the sexual generation is not necessarily bound up with the formation
of spores, but that, under conditions injurious to the formation of
spores, different cells, both of the seta and the capsule, are capable
of producing a protonema.

The Origin of Pycnidia.—A difficult research is that which has
been made by Dr. H. Bauke, and which is recorded in the ‘ Nova
Acta’ (Band 36), Dresden, 1876. The original paper is abstracted at
considerable length in the ‘ Journal of Botany’ (January), from which
the following conclusions may be taken as stated by the author :—“ As
to the question whether the Pycnidia are independent organisms, or
whether they belong to the Ascomycetes, these researches prove the
second of these alternatives to be correct. The cultivation of the
Ascospores of Pleospora polytricha, Cucurbitaria elongata, and Lepto-
spheeria (Pleospora) Doliolum regularly yielded Pycnidia—in the first
of the three species named such bodies were up till now unknown; in
this case the direct connection between the sown Ascospores and the
Pycnidia was each time established. From Pleospora herbarwm, in
spite of numerous cultivations instituted for the purpose of studying
specially the development of the Perithecia and the Pleomorphism of
this fungus, I obtained only twice Pyenidia. . . . In the cultivation
of Melanomma (Spheria) Pulvis-Pyrius and of Pleospora pellita a dense
mycelium was regularly produced, on which in the latter species the
Conidia drawn by Tulasne appeared in masses, but no Pyenidia, which
were indeed never found on either, &c. From Cucurbitaria Laburni
and Pleospora Clematidis the same results were obtained, namely, no
Pyenidia. Pycnidia appear as parasites on other Ascomycetes (as in
the case of Cincinnobolus and Erysiphe) only as distinct exceptions.”

Tubular Degeneration of the Medullary Nerve Sheath. — The
‘American Journal of Insanity’ (January 1877) says that in partial
softening of the spinal cord, and in grey degeneration, Professor
Arndt observed—by examining transverse sections, coloured with car-
mine—the medullary sheath to consist of concentric layers. As the
medullary substance showed an inflated condition, there was no doubt
of a pathological alteration; but still, Arndt believes that it also
establishes the true structure of the sheath, which normally, very
probably, grows by forming concentric layers.

Are Volvox globator and Sphcerosira volvox distinct Species ?—This
question has at length been answered in the negative by Mr. W. H.
Gilburt, who has a short but important paper on this question in the
‘Journal of the Quekett Club’ (February 1877). The relationship

PROGRESS OF MICROSCOPICAL SCIENCE. 211

was suspected years ago by Mr. Busk, but it is now clearly defined.
Mr. Gilburt says that he lately obtained some water from a pond in
Epping Forest, near Walthamstow, containing Volvox globator in great
numbers. On first looking at them, nothing particular was observed,
save that many were decaying, and were occupied by one or more
rotifers and their eggs. Making a more careful examination, he found
that in some of the vigorous and more active ones, a difference between
the macro-gonidia existed—some of them being smaller in size, lighter
in colour, and the disposition of their gonidia less regular. Using a
higher power, the difference became more marked, and under a power of
350 diameters those which departed from the supposed normal character
appeared as the author has represented them in the drawing which
accompanies the paper, a sphere as an ordinary Volvowx, but that some
of the gonidia were missing, and their places occupied by compound
bodies, in this and every other respect agreeing with the figures of
Spherosira as given both by Ehrenberg and Busk. Submitting them
to pressure so as to rnpture the cell-wall, he found that the compound
bodies referred to escaped; and then appeared discoid in form, and
composed of about thirty cells, flask-shaped, having a nucleus, being
attached to each other by the smaller end, and furnished with abundant
vibratile cilia, which can be seen in both aspects as figured. The
action of the cilia imparts a slow, revolving, wheel-like motion to the
group, but with very little progression. This motion can sometimes
be seen while they are still within the containing sphere. In a single
Spherosira as many as fifty-five of these compound bodies have been
found. One most remarkable feature is, that while the Volvow globator
may contain from two to seven macro-gonidia, yet in only two instances
has he found more than one Spherosiva among them; though a very
large number have been examined for this special purpose.

The Formation of Spores in Lichens and Fungi.—A valuable essay
on this subject has been translated from the French of M. Strasburger
into ‘Grevillea’ for March. We can only abstract a few of the
observations, more especially with reference to Physica ciliaris. The
author says with regard to this species his own special researches
show that the primitive nucleus really exists, and is found in the
upper portion of the claviform ascus before the production of the
spores. The ascus is filled with a protoplasm nearly uniform in
density, and possesses a thick and very turgescent wall. The nucleus
is spherical, especially dense and refractive in its upper part, as the
examination of preparations preserved in alcohol demonstrates. The
ascus augments in volume, the primitive nucleus disappears, and eight
spores simultaneously arise in the superior part of the ascus. These
spores approach each other closely, and absorb for their formation
nearly all the superior protoplasm of the ascus. The spores appear
complete. In the centre of each of them we observe a denser, although
badly circumscribed spot. The young spores are at first solid, and
surround themselves very rapidly with a colourless membrane of
cellulose, which quickly increases in thickness. At the same time
they increase in size, and their protoplasmic contents retire towards
their walls. The denser, and at first central portion, which is an

212 PROGRESS OF MICROSCOPICAL SCIENCE.

irregular or stellate granule, becomes equally parietal, and appears to
be equivalent to a nucleus, for it immediately doubles itself, and
displays between its two moieties a partition of protoplasm, by means
of which the spore, which has become ellipsoid, is divided along its
smaller axis, into two equal parts. But this nucleus is so small that
we are unable to observe the details of its division. In the partition
of protoplasm, there is formed at the same time a new wall of cellu-
lose, which speedily acquires a great thickness. The two small nuclei
which generally are at first fixed near the new wall, cannot be dis-
tinguished from the other granular contents of the spores, until these
acquire a greater age. Finally, the membranes of the spores which
have become bicellular, rapidly acquire a colour, which becomes
deeper and deeper, from grey to brown. The small quantity of pro-
toplasm which surrounds the spores becomes tinted always, by iodine,
of a yellow-brown.

The Blood-globules of different Races of Man.—Dr. J. G. Richardson,
of Philadelphia, has sent us an important paper which he has published
on this subject in the ‘American Journal of Medical Sciences.’ He
determined to obtain from the several individuals of different parts
of the world who went to the American Exhibition last autumn,
specimens of their blood. And he thus describes the results :—“ The
samples were each procured by myself from the individuals mentioned
(sometimes only through much persuasion), by puncturing a finger
with the quick stab of a cataract needle, pressing out a small amount
of blood, applying a clean slide to the apex of the drop, and then
spreading out the portion of fluid which adhered to the glass, with the
end of another slide, according to Professor Christopher Johnson’s ex-
cellent method. The measurements were all made with a ,';th immer-
sion objective and by the aid of a cobweb micrometer eye-piece, giving
when thus combined a power of 1800 diameters. The value of the
degrees of the eye-piece micrometer with this objective, at the cover
correction employed, was determined by a stage micrometer kindly com-
pared for me by my friend Col. J. J. Woodward, of Washington, D.C.,
with one carefully tested by the standard in the U.S. Coast Survey
Office, and which he has pronounced practically correct. Instead of
measuring all corpuscles, deformed or otherwise, in two directions, as
proposed by Dr. Woodward,* I prefer to determine the size of un-
altered, i.e. circular corpuscles only. By this plan, which I believe
is that of our highest authority upon the subject, Professor Gulliver,
we obtain the dimensions of nearly normal cell elements, such as are
exhibited in Dr. Woodward’s beautiful photograph of fresh blood,}
where, as in fluid preparations, but little variation in size exists among
the corpuscles; and escape being misled by pathological specimens
similar to those displayed in photograph No. 836, of the same in-
valuable series. Since the chief cause of marked variation in magni-
tude as well as of distortion in shape among blood-disks spread out
upon glass is, I think, their mutual attraction and repulsion during

* ¢ Phila. Med. Times,’ vol. vi. p. 457.
+ ‘Army Med. Museum,’ No. 861, New Series.

PROGRESS OF MICROSCOPICAL SCIENCE. 213

the process of drying, my investigations were made upon portions of
. slides where the corpuscles were very sparsely disseminated, and then,
to secure the most infallible accuracy for my deductions, as the pre-
paration was moved along, I measured every isolated circular red
disk which came into the field of the microscope. In doing this I
cautiously avoided recording those which manifested even slight
departures toward an oval form, and by several experiments learned
that the deviation corresponding to a transverse diameter of 5,),, and
a conjugate of 5,!;, of an inch was recognizable by a single glance.
One hundred corpuscles in each specimen were measured and the
dimensions as I read them off in millionths of an inch noted down
generally by an assistant. These memoranda, with the preparations
to which they refer, are carefully preserved for examination by any
experts who may desire to convince themselves respecting the sub-
stantial foundation of fact whereon I base my conclusions.” Here
follow the several results, which have been put in a more convenient
form by the editor of the ‘American Naturalist’ (March 1877) than
they have in the original paper :

~ if re aga 2 3/8
& tS) = ra og SEs od
NATIONALITY OF & | Le SE | Ag Az leu8| sto lecs
SUBJECT. oa og oe g B g& | e888] on8| 088
S | tel i irshies a5 = | wo | wa
Gilat, (ee: tars lalieo. ue suns S eae el
sare F sinlgtl oe 4 vines | g57| 33
e GeaPnes cpaer stank
Japanese Sel LOO Esa eon e 23787) eS ele so ag
Spanish .. .. | 30| 100 |1-3296/1-2777|1-3571/ 6 | 89 5
Belgian .. .. | 88] 100 | 1-8203/1-2777|1-3846| 7 | 88 5
Swiss .. .. .. | 40 | 100 | 1-3203/1-2857|1-4000| 7 | 82 | 11
Turkish .. .. | 29 | 100 |1-8197|1-2777|1-3846| 4 | 80 | 16
Danish .. .. | 25| 100 | 1-3257|1-2857|1-4000; 12 | 82 6
RUSstane ee altel On I—St9Oy 1 ~2857 | 1-3971 Ae oy 7
Norwegian .. .. | 35 | 100 | 1-8252 | 1-2857| 1-4000; 10 | 86 4
Swedish .. .. | 33| 100 | 1-8254/1-2777/1-8737/ 13 | 82 5
Italian .. .. | 35 100 |1-3272|1-2777|1-4000| 10 | 83 7
French .. 67 | 100 | 1-3239 | 1-2777| 1-8737| 12 | 80 8
al 52 | 100 |1-3229|1-2857|1-3856| 11 | 83 | 6
Cherokee Indian;\) 4g | 400 | 1-3215|1-2857/1-4000/ 10 | 83 | 7
born in U.S. .. f| |
English parent- 9791 | 1.9777 | 1_294@ |
Le ere | 40 | 100 |1-8191|1-2777|1-3846| 6 | 85 9
Total .. | .. | 1400 | 1-3224 | 1-2777|1-4000} 8 83 9

“ Combining these deductions, we find that of the wae 1400 cor-
puscles each separately measured, the SEE Was s5'sy (°007878
mm.), the maximum ;,/,,, and the Sen FO00, of an inch; 1158
or 83 per cent. measured between 7,5 and x9 of an inch in
diameter, and consequently under a power of 200 would appear about

214 PROGRESS OF MICROSCOPICAL SCIENCE.

the same magnitude; 118 or about 8 per cent. were less than 34x,
and 124 or nearly 9 per cent. were more than .,),, of an inch in
diameter. The total number of corpuscles ;,5 of an inch across
was 6, or less than one-half of 1 per cent. The total number 57,7
of an inch in diameter was 10, or less than 1 per cent. 'The somewhat
smaller averages of the Italian, Swedish, and Norwegian specimens
are perhaps due to slight accidental variations in spreading out the
layers of blood for examination, and cannot be accepted, at least
without further research, as indicative of either personal or national
peculiarities.”

MicroscoricAL Contents oF ForEIGN JOURNALS.

The following brief notices of foreign journals of interest to the
microscopist are taken partly from ‘Nature’ and the ‘Journal of
Botany’ (for March) :

Morphologisches Jahrbuch, vol. ii. part 4.—On the Development of
the Auriculo-ventricular Valves of the Heart, by A. C. Bernays.—On
the Segmentation of the Ovum and Formation of the Blastoderm in
Calyptrea, by A. Stecker.—On the Primitive Groove in the Chick, by
A. Rauber.

Revue des Sciences Naturelles, vol. v.. No. 8, December 1876.—
Contributions to the Natural History and Anatomy of the Ephemeride,
by N. and E. Joly; an important paper.—On Parthenogenesis in
Bombyx mori, by Carl von Siebold.—On the Histology of the Egg, by
A. Villot, dealing with theoretical views on the germinal vesicle and
its history.

Bot. Zeitung, January 1877.—H. de Vries, “On the Expansion of
Growing Cells from Turgescence.”—M. W. Beyernick, “On Plant-
galls.”

Flora, January.—L. Celakovsky, “On the Morphological Struc-
ture of Vincetoxicum and Asclepias” (tab. 1).— C. Kraus, “ On
Relations of Turgescence to Growth-phenomena.’—A. Batalin, “ Me-
chanism of Movements of Insect-eating Plants.’—V. A. Poulsen, “A
New Locality for Rosanoff’s Crystals.”

(Esterr. Bot. Zeitschr.—* On the Occurrence and Origin of Etiolin
and Chlorophyll in the Potato.”

Bull. Bot. Soc. France, 1873, pt. 8.—E. Mer, “ Vegetative Pheno-
mena preceding and accompanying the fall of Leaves.’— Ripart,
“On New or Rare Cryptogams for Centre of France.’—E. Prillieux,
* Formation and Development of some Galls.”—E. Mer, “ Nature and
Functions of Evergreen Leaves.”—Id., “ Effect of Immersion on
Aérial Leaves.” .

Nuovo Giorn. Bot. Ital.—G. Briosi, “ On the Phytoptus Disease of
the Vine” (tab. 1). [This article we have had translated, and repro-
duced in the present number of the ‘ M. M, J.’ |—Id., ‘‘ On the Function

=

NOTES AND MEMORANDA. 205

of Chlorophyll in the Vine.’—G. Archangeli, “Ona Disease of the
Vine ” (tab. 3).—G. Cugini, “ On the Hairs of Species of Plantago”
(tab. 4—6).

Zeitschrift fiir Wissenschaftliche Zoologie, vol. xxvii. part 4, 1876.—
On the Anatomy of the Ophiuroid, Ophiactis virens, by H. Simroth,
seventy pages, five plates.—On the Structure of the Brain in Arthro-
pods, a Memoir describing the brains of Apis mellifica, Gryllus cam-
pestris, Gryllotalpa vulgaris, Carabus viol., and Astacus fluviatilis, by
M. J. Dietl, of Innsbruck, thirty pages, three plates.

Reale Istituto Lombardo di Scienze e Lettere, Rendiconti, vol. x.
fasc. 1—On Helminthosporium vitis (Lev.), a Parasite of the Leaves of
the Vine, by M. Pirotta.—On the Phenomena which accompany the
Expansion of Liquid Drops, by M. Cintolesi.

Ofversigt of the Stockholm Acad. of Sciences, 1876, No. 6.—
Dr. Nordstedt and Dr. Wittrock have published a paper in this on the
Desmidice and Afdogonia of the Tyrol and Italy. Two excellent plates
display the several novelties.

In Naturforscher (January 1877) we note the following papers :—
On the Germination of the Fruits of Mosses, by P. Magnus.—On the
Preparation of Pure Alcohol Yeast, by Moritz Traube.—New Re-
searches on Bacteria, by E. v. M.—On the Exhalation of Carbonic Acid
and the Growth of Plants, by L. Rischawi.i—Researches on Assimila-
tion in Plants, by A. Stutzer.

The Memoirs of the St. Petersburg Society of Naturalists, vol. vii.,
contains a series of valuable physiological contributions, the most im-
portant of which are :—On the Comparative Anatomy and Metamor-
phology of the Nervous System of the Hymenoptera, by E. K. Brandt.
—QOn Changes in the Hye produced by the Section of the nervus
trigeminus, by M. Chistoserdotf.—On the Nucleus of the Red Globules
of the Blood, by A. F. Brandt.

NOTES AND MEMORANDA.

Death of Dr. Bowerbank.—It is with great regret that we have
to announce the death of one of our most distinguished Fellows,
J. S. Bowerbank, LL.D., F.R.S., which occurred at his residence at
St. Leonards-on-Sea, on March 8, and which we believe was caused
by an attack of bronchitis. He had lived beyond the time that is
generally allotted to us; that is to say, he had more than completed
his threescore and ten years, being in fact eighty at the period of his
death. He has not of late communicated anything to the Society, but
he was not on that account idle. On the contrary, he was at work almost
till his decease. Indeed, it is but a few months since a paper of his
on the Spongiade was read before the Zoological Society. Besides his

216 NOTES AND MEMORANDA.

various papers on zoology, communicated from time to time to the
different associations, the great work by which his name will be
remembered is the ‘ Monograph of the British Spongiadex, a book
published in 1864 by the Ray Society, and which has been admirably
illustrated by Mr. Lens Aldous.

Mr. Bridgman’s Mode of Polishing a Speculum. — In a paper
published in the February number of the ‘Quekett Club, Mr. Bridg-
man gave an interesting account of a new universal reflecting illu-
minator, which we regret that we cannot condense, as without the
illustrations our remarks would be unintelligible. However, he also
appended some observations on the above subject which are worthy of
being recorded here. He says :—Having obtained the silver plate,
and had it soft-soldered to a brass back and cut to the size, let a piece
of sealing-wax or a small block of thick plate glass be attached to its
back as a handle and to prevent flexure. Now procure a common
writing-slate with a flat and smooth surface, and grind the silver with
water until all scratches have disappeared, and a level face has been
produced. If the surface be now well burnished with a straight
burnisher it will add greatly to the brilliancy and durability of the
polish. Next, take two pieces of thick plate glass, not less than three
or four inches square, and upon the surface of one melt some pieces of
clean pitch until soft enough to be spread evenly with a hot knife to
about the thickness of a sixpence. Let the surface of the other glass
be smeared with soap and water, and then pressed upon the soft pitch
until the latter shall have acquired a flat and highly polished surface,
when it may be slid off, and the pitch left to harden. Obtain at the
chemist’s a pennyworth of “ precipitated carbonate of iron” (the softest
and finest “rouge” possible), and mix with a few drops of water to the
consistence of cream, and let the metal be lightly worked with this
over all parts of the pitch in small circles, carefully avoiding all dirt
or grit until the polish, commencing in the centre, shall have spread
to the edges, and have a deep and brilliant lustre that will reflect
objects with the utmost sharpness of definition.

A New Microtome for cutting a series of sections was recently
described to the Boston Society of Natural History, by Mr. C. 8.
Minot. We have not yet seen any description of the instrument.

Mr. Spencer’s Objective.—In our last number we described an
objective of Mr. Charles A. Spencer, on the authority of the ‘Cin-
cinnati Medical Journal.’ We now learn from that Journal that
the object-glass referred to was not made by the veteran Spencer,
but by his son, who, it states, with his father, and brother-in-law,
O. T. May, is engaged in the manufacture of microscopes, under the
“firm name” of Charles A. Spencer and Sons, in connection with the
Geneva Optical Company. The immediate work of making these
fine lenses is done by Mr. Herbert R. Spencer. The glass alluded to
is a three-system lens, and is of 170° angle of aperture, instead of
160° as stated.

CORRESPONDENCE.

MicroscoprcaAL CENTENNIAL HixHIBITIon.
To the Editor of the ‘ Monthly Microscopical Journal.
7, WiemMorr STREET, CAVENDISH SQUARE,
February 20, 1877.

Sirn,—The January number of the ‘ Monthly Microscopical
Journal’ contains a review of the microscopes in the Centennial
Exhibition at Philadelphia, in which the writer, Dr. Ward, while
giving a most favourable notice of our exhibit, and expressing himself
in a handsome manner as to the style and finish of our instruments,
makes a remark which we fear may possibly bear a wrong inter-
pretation. Referring to our objectives on Wenham’s new formula,
Dr. Ward states that they were “ understood to have been entered
for competition and then permanently removed from the Exhibition
and the country.” This would imply that they were taken away
before being examined, but this was not the case, as the judges tested
the whole series critically on several occasions, and it was not until
they informed our representative that their examinations were com-
pleted that the glasses were removed from the building. We may
add, that the judge’s Report is now in our possession, and that it is
highly commendatory to both our microscopes and new objectives.

We are, Sir, yours obediently,
Ross anp Oo.

ON THE MEANS OF CENTRING OBJECTIVES AND Roratina
STAGES.
To the Editor of the * Monthly Microscopical Journal.’
February 28, 1877.

Si1r,— All who work with high powers, and use high-angled achro-
matic condensers, have, no doubt, felt the inconvenience of the con-
centric rotating stage being eccentric, not only with different objectives,
but even, very often, with the one to which it may have been adjusted;
and they may also have observed that the achromatic condenser, not-
withstanding that it may have been carefully centred, will sometimes
become eccentric.

These defects are, of course, much less apparent in the very best
workmanship.

The means of “accurately centring the stage to the highest power
objective” was introduced in 1875,* and later in the same year {+ the
“concentric rotating stage having rectangular mechanical adjust-
ments” was brought before the Royal Microscopical Society. Both
these plans are based on nearly the same principle, and the result
aimed at is to render the rotation of the stage concentric with any

* «Science-Gossip, September 1875, p. lxvii.; and ‘M. M. J.’ No, Ixxxi.

September 1875 (cover).
+ ‘M.M. J.’ No, Ixxxv. p. 54, January 1876.

218 CORRESPONDENCE.

objective that the observer may wish to employ. But neither plan is
of any use for centring objectives to the achromatic condenser when it
is eccentric; moreover, the above-adjustments are cumbersome, because
they must be fixtures, and their use is limited.

The “new centring nose-piece” is, in my opinion, a great boon
to observers who work with high powers on ¢est objects. Test work
may not be very instructive, but it is undoubtedly the cause of the
great improvements made on some of the modern objectives; it is also
fashionable, not only among amateurs, but even among savants; and
therefore any new apparatus that facilitates the attainment of accuracy
should be welcomed.

The centring nose-piece is made by Mr. Swift, and it figures in
‘Science-Gossip’ for February, page xv. The rectangular adjust-
ments act in the same manner as those of the sub-stage, and the
objective is thereby adjusted to the optical axis of the instrument.
This nose-piece has the following advantages, namely: Ist, it is not a
fixture, and it works with any microscope fitted with the “ universal
screw”: 2nd, it may be used to rectify the eccentricity of the achro-
matic condenser caused either by the “spring” of the fine adjustment
when moving the screw-collar of the objective, or by the unsteadiness
of the sub-stage; and also to centre any objective to the achromatic
condenser fitted to a microscope without any under-stage adjustments:
8rd, it may also be used to render the rotating stage concentric with
any objective. The only drawback is that this nose-piece may slightly
strain the fine adjustment.

It must be taken into consideration that neither the centring of
the stage, nor that of the objective, is obtained “instantaneously ”
nor “with the greatest facility ”: in either case the adjustments must
be made very carefully.

I am, Sir, yours obediently,

A. DE SouzA GUIMARAENS.

Nore ON THE STRUCTURE oF THE TEest IN ARCELLA.
To the Editor of the ‘ Monthly Microscopical Journal.

Sir,—In the ‘ Quarterly Journal of Microscopical Science’ for
January last, p. 79, the following statement appeared :

“For the first time seemingly a correct description of the structure
of the peculiar test of the somewhat variously and otherwise pretty
well known and at least common species Arcella vulgaris (Ehr.), is
given by Hertwig and Lesser. Two plates, an outer forming the
superficies of the test, an inner applied to the body of Arcella, are
united in a honeycomb-like structure, whose hexagonal cavities form
prismatic spaces standing vertically on the surface. Hertwig and
Lesser conclude that the appearance of the markings on the Arcella
test is not due to granulation as Dujardin supposed, or Claparéde and
Lackmann as well as Carter assumed. Wallich indeed spoke of
symmetrical reticulation and of hexagonal interspaces ; still Hertwig
and Lesser doubt if he altogether correctly appreciated the structure,

PROCEEDINGS OF SOCIETIES. 219

as how otherwise could he come to the conclusion that Arcella vulgaris
could be but a sub species or even a species of Difflugia ?”

What on earth my conclusions regarding the limitation of species
in these lower forms of animal life have to do with the correctness or
incorrectness of my published description and figures of the structure
of the Arcelline test I am at a loss to conceive. The one is a matter
of opinion ; the other a matter of fact. I am quite ready, however, to
allow that in my humble opinion our knowledge of the biological re-
lations of the Protozoa and Protophyta is much more likely to be
increased by taking into due consideration the causes on which
divergence is mainly dependent, than by seizing upon every trivial
variation from an assumed type as evidence of specific distinctness.

How far it is admissible to say that “a correct description ” of the
structure of the test of Arcella was given “for the first time) by
Messrs. Hertwig and Lesser,” and that I merely “spoke of sym-
metrical reticulation and hexagonal interspaces,” the subjoined extract
will at once show. I may mention that it is taken from the explana-
tory references which accompany the plates illustrating my memoir
‘On the Extent and Causes of Structural Variation among the Dif-
flugian Rhizopods;’ and that a detailed figure is there furnished of
the structure as it exists in Arcella.

“Fig, 87. Front view of D. arcella. Fig. a shows the invariably
hexagonal pitting or reticulation of D. arcella (Arcella vulgaris). This
can only be made out, however, in a mounted and crushed test, under
a high power.” *

I remain, Sir, your obedient servant,

G. C. Watuico, M.D., &c.

PROCEEDINGS OF SOCIETIES.

Royat Microscorican Society.

Kine’s Coutuece, March 7, 1877.

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 previous meeting was
ie by the Secretary, and the thanks of the Society were voted to the

onors.

The President had great pleasure in announcing that there was
every reason to believe that arrangements would be made with Sir
John Lubbock to deliver the first Quekett lecture to the Society on
May 2. The subject would in all probability be “The Microscopie
Characters of Ants in connection with their Habits and Instincts.”
The Quekett medal, which had recently been struck for the purpose,
would be presented to Sir John Lubbock at the close of the lecture.
F eee and Mag. Nat. Hist.’ March 1864. Explanation to plate xvi-

g- .
VOL. XVII. R

220 PROCEEDINGS OF SOCIETIES.

Tickets would be issued to the Fellows for the admission of them-
selves and one friend, and the use of the large theatre of the College
had been obtained for the purpose. He added, the Council had
arranged to have another scientific evening meeting on Wednesday,
April 18, of which due notice would be given.

The Secretary read a letter which had been received from Mr.
Frederick Ebsworth, of Australia, describing a method of estimating
and recording the dimensions of small objects, or the fineness of
wool. An explanatory diagram accompanied the letter.

The thanks of the meeting were voted to the writer for his com-
munication.

A paper by the Rev. W. H. Dallinger was read by the Secretary,
entitled “ Additional Note on the Identity of Navicula crassinervis,
Navicula rhomboides, and Frustulia Saxonica.” (The paper will be
found at p. 173.)

The President, in proposing a vote of thanks to Mr. Dallinger,
said that the subject was one to which he had himself paid little or no
attention, and therefore it would be out of place for him to say any-
thing about it; but he thought it must be plain to everybody present
that the method adopted by Mr. Dallinger could not fail to be the
right one. He was sure that they would all be very glad to hear that
Mr. Dallinger was about to receive considerable help in making his
very interesting and important investigations—the sum of 100/. having
been voted to him by the Royal Society from the Government Grant
Fund of 40002. in order to further the progress of the observations
upon which he was engaged.

A vote of thanks to the Rev. W. H. Dallinger for his paper was
unanimously carried.

Mr. Ingpen said he was hardly in a position at a moment’s notice
to make remarks upon the subject of the paper which were of sufficient
value to be worth their attention. The points of his former observa-
tions were directed to the use that should be made of generic names
rather than to the identity or otherwise of the forms themselves,
and the question of making use of one name for a large number of
apparently different forms. He could not help fancying, however,
that in a certain group there were collected together a number of
diatoms in which, although there was the same arrangement of mark-
ings, and therefore a good generic character, there were differences in
other respects, and that these differences had been made use of for
purposes which were not legitimate. For instance, the Rhomboides
was put forward by one maker as a test for a particular objective, and
another maker would produce a glass which would resolve a coarser
form, also called Rhomboides. This would not be a fair test. He
quite agreed with Mr. Dallinger that out of a great number of slides
it was possible to find every intermediate variety between two forms,
but what they really wanted was the establishment of something
like type species. In the case before them they had three distinct
forms and many varieties between them, and he quite agreed that
the generic term of Frustulia was totally unnecessary. Yet which
were they to take as their type form—as a test? He thought they had

PROCEEDINGS OF SOCIETIES. 221

something like a starting point in the original Navicula rhomboides
—they had its shape, its markings, and its median line, it was figured
in “Smith,” and would be a very good one to start from. Then in
the same book they had also N. crassinervis, or crassinervia, which had
distinctly different ends, was round at the sides, and had the ends of
the median line terminating in distinct nodules, compared with which
N. rhomboides had its sides straighter, was more generally rhomboidal,
and its median line terminated in blunted lancet-shaped points.
Between these two they could easily get every variation leading
from one to the other, and he thought it was most important from
amongst these varieties to get a well-established typical Rhomboides
and a typical Crassinervis. What had happened was that for some
time they had one form only, after that a coarser form was brought
forward as a test for a+ inch; it was much rounder at the sides, and
there was a difference in the centre and ends of its median line,
which were flattened and battledore-shaped; and then after this
they got another form from the Cherryfield diatoms. On the same
slide they might see the original Rhomboides and the new specimen.
He thought that in this respect Moller had done a great deal towards
creating this confusion, for on his type slide they found Rhomboides;
but it was the big form, and nothing at all like the Rhomboides of
Smith, whilst next to it was what he called Crassinervis—exactly
the same as the original Rhomboides, but nothing at all like the
Crassinervia of Smith. He should be one of the last to increase the
number of genera and species upon insufficient data, but thought they
ought not to group together forms which differed so greatly from
the type given as that of the species. They wanted at least to know
what they were talking about, instead of getting one so mixed up
with another that as test-objects they might be used for what might
be called illegitimate purposes and so became of little value.

Mr. Slack said the paper raised a very wide practical question,
and one which was not confined to diatoms. When a botanist was
able to show that certain extreme forms were connected by a series of
intermediate gradations, he was justified in placing them together in the
same group notwithstanding their differences, just as a greyhound and
a bulldog were both classed as dogs. In order to know what they
were talking about, where there were a great number of so-called
species in the question, it was well to retain distinctive names for
them for purposes of identity even long after it had been shown that
they had no claim to be spoken of as belonging to different genera or
species.

Mr. Charles Brooke said it appeared to him as a general question
that it was quite impossible to assign two individuals to different
genera when there was a series of intermediate forms which might be
found passing from one to the other. It might be desirable to know
the various forms by different names—as in the case of dogs already
mentioned—but they should not be known as distinct species, and this
should never be done where such gradations existed. This gradation
of form had been traced throughout the whole class of the Foramini-
fera to a far greater extent than amongst the diatoms, and amongst

R 2

222, PROCEEDINGS OF SOCIETIES.

them they found immense differences out of all proportion to those of
the diatoms, but all unquestionably belonging to the same species,
and amongst which it would be impossible to draw any lines if they
tried to make them into distinct species.

The President said the subject was one which certainly was not
confined merely to diatoms, but which equally belonged to every
department of science, only that it happened in the case of diatoms
that they had the opportunity of examining so great a number of
individuals that the variety would be in a measure proportionately

great.

Donations to the Library and Cabinet since February 7, 1877:

From

Nature. “Weekly 2.) 5 se Gee ee sib ny ae oie ret
Atheneum. Weekly .. SE tale he Voom oc Ditto,
Society of Arts Journal. Weekly POI osc) pp) SECU
Quarterly Journal of the Gealbaical Society val | (lea a emperor nO
Bulletin de la Société Botanique de France... Teloysh hou MRED CRE
Enumeracion de los Vertebra dos Fosiles de Espatia. “Par Don

C. Calderon, 1877 .. toe ane Cnn .. Author,
Journal of the Quekett Club. No. 33 : .. «= Chub.
Micro-photographs from the Diatomaceze. ‘By x Redmayne .. Author.
Some Remarkable Forms of Animal Life from the Great Deeps off

the Norwegian Coast. Part 2. By George O.Sars .. .. Ditto.
On the Practical Application of Autography in Zoology, and ona

New Autographic Method. By G.O.Sars_.. Ditto.
Eleven Stained Preparations, &c., peer abe: Dr. Christopher

Johnstone, of Baltimore ae we — Ditto,
Twelve Slides ‘of whole Insects .... va aes cele) ER EEEDC ee REESC «

G. H. Jones, Esq., was elected a ‘Fellows of the Society.

Watrer W. ReEevss,
Assist.-Secretary.

Meprioat Mioroscorioan Soolety.

February 16, 1877.—Henry Power, Esq., President, in the chair.
Hyperemia of the Brain from Hanging.—Dr. Browning exhibited
some interesting specimens illustrative of this subject. Two were
taken from executed criminals, and were prepared by Surgeon-Major
Roth, of Berlin, and one was from one of the lower animals that had

been hanged for experiment. The brains were, in all cases, injected

with carmine. In his remarks upon these specimens Dr. Browning
stated that whereas most medico-legal writers describe only a medium
amount of vascularity in the brain and that of venous character, and
extravasations as very rare, he had found the congestion most intense :
the capillaries being so distended in some parts that scarcely any
nerve substance was to be seen: however, he had not found any extra-
vasations of blood. As cause for the vascularity, the speaker suggested
that the knowledge of his fate might, in the case of the criminal,
cause some hypercemia at last, though this could not hold with the
lower animals.

The cerebellum he had found more vascular than the cerebrum.

The President suggested that the vascularity was owing to pressure

PROCEEDINGS OF SOCIETIES. 723

on the veins, while the arteries could, from not being so compressed,
still force up more blood, He thought that the knowledge of his fate
would rather make the criminal’s brain ancemic than hypercemic. The
lower part of the spinal cord was undoubtedly congested, as shown by
the frequency of priapism in these cases.

After some further remarks from various members, the meeting
resolved itself into a conversazione to exemine the specimens.

Liverroot MicroscoricaL Society.

The annual meeting of this Society was held on Friday, January
19, at the Royal Institution, the Rev. H. H. Higgins, M.A., in the
chair. The annual report of the Committee stated that the number
of members on the books of the Society was much the same as last
year, and that the financial position of the Society was satisfactory.
Important donations have been made of valuable slides to the So-
ciety’s cabinet during the session; and also a further number of
books have been added by donations and purchase to the library.

The Committee congratulated the Society on the fact of the Presi-
dent, the Rev. H. H. Higgins, having consented to retain the office of
president for another year, in consequence of his prolonged absence,
occasioned by his having, on the nomination of the Library, Museum,
and Arts Committee of the Town Council, joined the ‘Argo’ scien-
tific expedition to the West Indies, which has resulted in some very
valuable additions to our local collections.

The President delivered his inaugural address. In the course of
it he said: Your kind reception of my paper on “Lines of Animal
Life,’ consisting chiefly of remarks on the Stammbaum des Thier-
reichs of Professor Koch, induces me to hope that a similar attempt
to illustrate the vegetable kingdom may be acceptable, and the sub-
ject of my address this evening is “Lines of Vegetable Life.”

Thanking you for the favour of occupying during the second year
the honourable position which I hold as your President, my best
apology for so very brief a preface may be the interest and magnitude
of my subject.” In concluding the address, the President said:
“To appreciate these facts in nature it is not necessary to regard
the theory of evolution as if evolution were unconditioned or of
universal application ; at the same time it must, I think, be admitted
that in the absence of that theory the facts themselves would be in-
comprehensible, or would possess comparatively little interest.”

The second ordinary meeting of the ninth session was held on
Friday, February 2, at the Royal Institution, Colquett Street; the
Rev. H. H. Higgins, M.A., President, in the chair. The Hon. See.
(Mr. Chantrell), in announcing the donations, read a letter he had
received from Mr. G. B. Rothera, of Nottingham, who was present as
a visitor at the annual meeting, and heard the President’s inaugural
address, the subject of which was “Lines of Vegetable Life.” To
show his appreciation of the address, and his desire to see it pub-
lished, he enclosed 5/. as a donation to the Society’s funds. Mr,

224 PROCEEDINGS OF SOCIETIES.

Joseph Birdsale Jones and Dr. J. Birkbeck Nevins were elected
ordinary members.

The Rev. W. H. Dallinger, F.R.MLS., gave a practical “ Note on
the Ultimate Limit of Vision,” as applied to our modern micro-
scopical lenses. Reasoning on certain data more or less theoretical,
mathematicians of the first order, notably Helmholtz, had concluded
that the limit of vision had been reached; that the optician could
practically aid us no further; that, in short, the limits of possibility
had been arrived at, since light itself is too coarse to reveal objects
smaller than those visible to our finest and most powerful lenses.
The limit marked out was about the one hundred and eighty
thousandth of an inch. But Mr. Dallinger gave instances of a re-
markable kind—the result of his personal investigation—directed
specially to this point, which were proved by a method of measure-
meut employed specially for the purpose to carry the power of our
most delicately constructed lenses considerably further than the
mathematician considered possible ; revealing, indeed, smaller objects
than those mathematically indicated ; and Mr. Dallinger did not by
any means believe that he had wholly exhausted the utmost power of
visibility by these experiments. A discussion followed, which was
chiefly concerned in eliciting more in detail the method employed in
these delicate measurements. The meeting concluded with the usual
conversazione, at which there was a good display of microscopes
and many interesting objects exhibited.

Ml BRUROsnteen
i

|
H q No

pyr

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THE

MONTHLY MICROSCOPICAL JOURNAL.

MAY-1, 1877.

I.—The various Changes caused on the Spectrum by different
Vegetable Colowring Matters. By Taos. Patumr, B.Sc.

(Read before the Royau Microscoricau Society, April 4, 1877.)
Puate CLXXIX.

Tue kind reception that I met at your hands on a former occasion
has encouraged me to trespass this evening for a short time on
your forbearance, while I lay before you the result of some observa-
tions that I have lately been making on the variability of the
chlorophyll band in the spectrum.

Chlorophyll, Fxcula viridis, or leaf green, is the name gene-
rally given to the green colouring matter of vegetables ; it is found
in nearly all plants growing in the light, with the exception of
fungi and the true parasites, covering either the cell-walls or the
spiral bands, as in Spirogyra, or the granular contents of the cells,
which are composed of starch, or other similar bodies. If plants
that have been grown in the light are placed in the dark, the
leaves fall; and if others are produced, they have a whitish colour :
again, if the plants that have been thus grown in the dark are
removed to the light, the leaves soon lose their white hue, and
eventually assume their natural colour; the rapidity with which
they become green, and the intensity of their colour, will be in
proportion to the amount of light to which they are exposed. The
different rays of the spectrum have a varying influence in pro-
moting the formation of chlorophyll, and some difference of opinion
exists as to which rays are the most active in this respect, but the
majority of experimenters agree that the yellow rays are those
which are the most essential, because they have the greatest effect
in promoting the decomposition of carbonic acid.

EXPLANATION OF PLATE CLXXIX.

Fic. 1.—Chlorophyl!1 normal. Fic. 7.—Petals of red Cineraria.
», 2.—Chlorophyll acid. Hil 8!
»» 3.—Leaves of Lobelia. » 9. ¢ Litmus. (Figs. in text.)
» +4.—Petals of blue Cineraria. syn LOE
», 0.—Leaves of Shumac. », 11.—Hypericene normal.
» 6.—Tradescantia. 5, 12.—Hypericene acid:

Note.—Class 1 isa symmetrical band. Class 2 is an unsymmetrical band.
VOL, . XVII. g

226 Transactions of the Royal Microscopical Society.

Mr. Fremy investigated the nature of this agent, and has
ascertained that it is composed of two colouring principles, one a
yellow, the other a blue; the former he has called phylloxanthin,
and the latter phyllocyanin. Both these principles have been
isolated by Mr. Fremy, who has also endeavoured to show that the
yellow colour of blanched and very young leaves is due to the
presence of a body which he has termed phylloxanthein, and which
is coloured blue by the vapour of acids. The same result occurs in
the discoloration of phyllocyanin; hence it would seem that this
phyllocyanin is not an immediate principle, but that it is formed
by the alteration of phylloxanthein, and indeed the spectroscopic
observations that have of late years been carried on in relation to
this subject, I am sure I may say by Mr. Sorby, tend to show that
chlorophyll is more complex than Mr. Fremy considered, as the
substances he treats of were probably only products of decomposi-
tion by acids.

The various shades of green seen in the organs of plants depend
upon very different causes; partly upon the nature of the chlor-
ophyll, whether it is pure, or more or less mixed with the yellow,
blue, or brown products of its decomposition—see Mr. Sorby’s
paper “On the Colours of Leaves at different Seasons of the
Year;” partly upon the quantity of chlorophyll in the individual
cells, partly on the thicker or looser arrangement of those cells, as
on the under sides of leaves, which are generally of a lighter green,
depending on the intercellular spaces which are there present, and
which reflecting the light, white, thus mix with and diminish the
intensity of the green.

When any form of chlorophyll is treated with ether or alcohol,
the colour is abstracted, while the organized forms, the corpuscles,
&e., remain, so that true chlorophyll is really only a soluble sub-
stance, dyeing the bodies called chlorophyll granules, &.; but the
various degrees of solubility depend greatly on the presence of
other substances, for instance, in the case of such evergreens as
laurel, ether takes hardly any effect, but alcohol thoroughly dis-
colours the leaves, whilst pyrethrum, a perennial, is hardly acted
upon at all by alcohol, but ether takes great effect.

If these solutions are evaporated to dryness, under the ex-
hausted receiver of an air-pump, a green fatty matter is left, which
forms soaps in combination with the alkalies. If this is again dis-
solved in ether, and mixed with water, and the ether evaporated,
small greasy globules are obtained, and similar globules are sepa-
rated from the alcoholic solution at a freezing temperature. If the
alcoholic tincture be mixed with water, and the alcohol evaporated
by heat, part of the fatty substance is precipitated; the remaining
solution is coloured a brown yellow, and has a characteristic smell,
like that of black tea. It is soluble in the volatile and fixed oils,

Changes caused on the Spectrum, &e. By T. Palmer. 227

but when treated with sulphuric acid it is either not changed or
else carbonized.

With regard to the second point or the colouring matter of
plants, the green colour, which forms the most extensive class, has
been treated upon in our primary consideration on chlorophyll; the
red and yellow colours, as assumed by the leaves in autumn, are due
to a chemical metamorphosis of the chlorophyll, and consequently
the discoloration of the cellular tissue: see also Mr. Sorby’s paper
“On the Various Tints of Autumnal Foliage.”* But independent
of all this, there are the colours of the red cabbage, copper beech,
and similar plants, all of which depend upon the existence of a
special colouring liquid in the usually colourless epidermal cells,
obscuring the chlorophyll which lies beneath. The bright colours
of plants, and other parts of the inflorescence, as also on the lower
surface of many leaves, Begonix Victoriz, for instance, as well as
numerous herbaceous shoots, arise from the presence of matters of a
different kind, almost always dissolved in the watery cell-sap. The
colour of petals is ordinarily found to depend upon a certain
number of the cells subjacent to the epidermal layer being filled
with a coloured fluid, and the depth of the colour is proportionate
to the number of superimposed layers of such cells, which act like
so many layers of a pigment: each cell is usually filled with one
colour when fully developed, but adjacent cells are often seen in
variegated petals to contain distinct colours, the line of demarcation
being accurately fixed by the cell-walls, through which the colours
do not transude unless injured by pressure. In young tissues the
colour has often a granular appearance in the cells, but this is a
deception, arising from the mode in which it is developed. The
colourless protoplasm, originally filling the cells, becomes excavated
as it were by water bubbles, and the watery contents of the
excavations become coloured ; they gradually enlarge, as the proto-
plasm applies itself more completely to the walls of the cell, until
they become confluent, and the coloared liquid fills the whole cell-
cavity. ‘The isolation of the coloured juice in each particular cell
seems to depend upon the primordial utricle, or parietal layer of
protoplasm ; when this is injured by pressure or other external
causes, endosmose is set up, and the integrity of the cell destroyed.
In some cases the liquid colouring matter of flowers has been
found to contain solid corpuscles; the red-colour cells of Salvia
splendens and the blue ones of Strelitzia regina contain globules,
and according to Von Mohl this is still more commonly the case
with the yellow colours. In the yellow, perigonal leaves of
Strelitzia regina, the colour is said to depend on the presence of
crescentic filaments, floating in the cell-sap ; the white patches also
on variegated and spotted leaves, such as those of Aucuba, Holly,

* “Quart. Journal Se.’ vol. i. p. 64. 9
8

228 Transactions of the Royal Microscopical Society.

variegated mint, Begonia, Argyro stigma, &c., arise from the
absence of chlorophyll in the cells subjacent to the epidermis at
those parts, which produces the same effect as we see in leaves that
have been mined by caterpillars.

Now it follows that the colouring agent which is found in
vegetables is in several states of combination; first, with the
extractive principle; secondly, with the resinous principle ; and
thirdly, with a starchy or gummy principle, and it is these states
which indicate the means of extracting them.

Firstly, when, as in the case of logwood, madder, &c., the
receptacle of the colour is of the nature of extracts, water is
capable of dissolving it.

Secondly, certain of the resinous colouring matters are soluble
in alcohol, spirits of wine, or ether, and form in many cases the
pharmaceutical tinctures: the other principle will be left, as it is
hardly in connection with our subject.

We will take as a standard the two solutions of chlorophyll,
viz. that in oil normal, and that also in oil acid.

In chlorophyll No. 1 we have a spectrum made up of four
bands, two of which are definite, and one shaded, while the other
is a general absorption of the blue end. Compared with this, we
have chlorophyll No. 2, or that to which a small quantity of acid
has been added ; we find on examination that a general displacement
towards the blue end has taken place, which result, as shown by
Mr. Sorby,* is due to a true decomposition of the original sub-
stance, obtained when acid is added,{ though it is not regained
when the acid is neutralized, as the normal action has gone too far
for subsequent recovery; a material transformation has, however,
taken place in the whole spectrum, the bands are constant though
displaced, while their ratios are almost identical; this will be more
clearly seen on reference to Fig. 2.

We deduce that the acid has transformed an original sub-
stance, which had the power of absorbing the rays of light, beyond
» 652°0; still another band is produced at » 662-0, and though
the bands 2 and 8 are proportionately shifted towards the blue,
and have likewise gained in intensity, the general absorption is
constant, and has sustained no apparent change: does it not
appear possible that, in the case of solutions contaiming more
acidity, this general absorption might be carried still farther into
the blue, as, for instance, in other of the colouring agents of plants ?
and if so, then in the event of an alkaloid form being also present in
combination, the same spectrum as Fig. 2 may be still maintained,
while the general absorption, &c., will be more nearly approached

* ‘Roy. Micro. Jour.’ vol. xiii.

+ See Mr, Sorby’s paper “On Comparative Vegetable Chromatology,” ‘ Royal
Society Proceedings,’ vol, xxi. p. 406,

‘Changes caused on the Spectrum, &c. By T. Palmer. 229
towards the red: take, for example, two vegetable colouring
matter spectra; first, leaves of Lobelia; secondly, petals of blue
Cineraria, for which I must refer you to Figs. 3 and 4.

Fig. 1.—CHLOROPHYLL IN O1L NoRMAL.

M. A. Observations.
1 | 23°955 | Centre .. .. | 652°0 | Class 1. Very black; size -510.
2 | 22-700 59 car pedal O0GrO » 1. Centre dark, ends shaded;
size * 200.
3 | 21°700 x ob on ae 7(OPar » 1. Very shaded ; size °400.
4 | 20°500 | Commencement | 515°5 | Shaded at first, terminating in a very
black absorption.
Fic. 2.—CHLOROPHYLL IN Orn AcID.
|
1 | 23°85 | Centre 662°0 | Class 1. Very black; size °5.
NOSES Sete een | OUSwe » 1. Shaded; size 3.
Si 295 a vo co | BBL » 1. Black; ends shaded; size °3.
4 | 20°5 Commencement | 515°5 | Shaded at first, terminating in a very
| black absorption.
Condition. | A. | A. | A. | Ratio.4
IharGybl Vac be 652°0 598°5 547-25 if 8 OGL
ET ACIGY tere 662°0 608°0 537°0 Ios) °9188

Fic. 3.—LEAVES OF LOBELIA IN ETHER.

M. A. Observations.
1 | 23:892 | Centre .. .. | 658°0 | Class 1. Very black; size °415.
2 | 22-650 5 sco, |) CULE », 1. Centre dark, ends shaded ;
size °3.
3 | 21:450 os Bo no | Eawe 3, 1. Very shaded; size °3.
4 | 20°050 s oe, | aa2rO » 1. Black; size °3.
5D | 26°6 Commencement | 512°0 | Very black; general absorption.

Fic. 4.—Buivur CINERARIA IN OIL.

1 | 22°44 | Centre .. .. | 615°0 | Class 1. Centre dark, shaded at ends;
size *435.

2 | 21°135 = co io || ore » 1. Centre dark, shaded at ends;
size 630.

3 | 20°0 + ss Ooo: O » 1. Very shady; size °4.

4 | 19°25 = «» « | 490°0 | Same as No. 1; size °d.

D> | 16°0 Commencement | 426°0 | General absorption.

a

230 Transactions of the Royal Microscopical Society.

In the former specimen, which is prepared in ether, we have
almost a facsimile of Fig. 2, though band No. 4 has disappeared ;
where it began however, a general absorption is evident, bands 1
and 2 are brought nearer the blue end, while No. 3 is farther from
it. The spectrum from the petals of blue Cineraria, Fig. 4, is
perhaps more striking, as the bands are all nearer the blue end,
while their symmetry with the preceding spectra is considerably
altered, still owing, no doubt, to the presence of an acid, though
comparison is hardly admissible, as the former specimens are
prepared from the green leaves, while the latter is extracted from
the blue petals of the flower.

We will now pass on to consider the spectrum of Shumac. This
substance contains a considerable percentage of tannic acid ; Mul-
ligan and Downing give 24°37 per cent. Having procured some
of the leaves of this plant from Palermo, I pulverized them, and
after due preparation the following solution in oil was the result ;
the spectrum, which will be seen on reference to Fig. 5, 18
curious enough to attract our notice, inasmuch as it almost agrees
with Fig. 2, though the bands are all more or less nearer the
blue end, yet the general absorption is increased towards the red.
In this case we have a distinct proof of an existing acid in con-
nection with the fluid; still there are differences, though to a less
extent than in the previously considered specimens; may we not
assume from this that the chlorophyll in the case of specimens
Nos. 3 and 5 is in combination with some alkaline base, while the
colour which is predominant in the case of No. 4, is of an acid
construction? At the same time I must acknowledge there is
every reason to think that an alkaline form is also present, though
to a much less extent. It must, however, be borne in mind that
this solution of Shumac is prepared from the dried leaves, and
therefore I doubt whether the spectrum from living leaves would
not be rather different from the one I have brought before your

notice.
Fic. 5.—SHumac.

M. A. Observations.
1 | 23°857 | Centre .. .. | 661-0 Class 1. Very black; size °485.
2 | 22°60 _ sey ae | 0000 » 1. Centre shaded, ends very
shaded ; size *20.
SWOT Bad, San ee ees DoOND 5, 1. Indistinct; size °3.
4 | 20-005 is .. .. | 5385°0 | Same as band No. 2; size 33.
5 | 20°465 | Commencement | 517°0 | Very black; general absorption.

But before leaving a subject which appears of some importance,
there is one more solution, that of Tradescantia, Fig. 6, which is
well worthy of our attention, as I think it bears especially on a

Changes caused on the Spectrum, &c. By T. Palmer. 231

point which I wish to make quite clear. You will notice in this
instance that band No. 1 is considerably more shaded than those
hitherto mentioned, besides being nearer the blue end; this same
effect occurs with bands Nos. 2 and 3, but unlike the other spectra
they are dark and well defined, though of Class 2, or unsymmetri-
cal, their terminations towards the blue being shaded,

Fic. 6.—TRADESCANTIA.

M. A. Observations.

iL || Bets} Centre .. .. | 611:0 | Class 1. Shaded; size -3.

2 | 21-175 a go on) || BLEW » 2. Black, shaded to the left;
size *7.

3 | 20°05 ‘5 532°0 » 2 Same as No. 2, though
lighter; size °5.

4 | 19:2 Bs SH ob. | eke nlots » 1. Shaded as No. 1, centre
darker ; size °6.

Band No. 4 will be seen to agree with the corresponding one
in Fig. 4, while the general absorption, which we have noticed
forms so characteristic a feature in all the previous spectra, is
entirely absent. Now it is just this fact which appears to me so
curious, for here we have a spectrum which, if I may use the
term, includes the whole of the other spectra, and yet it is so dif-
ferent, though to an extent. it is accounted for I think, when con-
sidered in connection with blue Cineraria, another part also of the
inflorescence, in which the chlorophyll is only disseminated in a
small degree, as compared with the leaves, &c.: then, with regard
to the comparison of blue Cineraria, Tradescantia is certainly more
astringent, but time and experience alone will answer these ques-
tions, and we will now pass on to consider the second part of my

subject. ;
. Part IT.

You will doubtless have perceived that hitherto I have only
taken those forms of plants which have some similarity to the
chlorophyll itself; we will now proceed to consider briefly the
totally different colours, such as red and yellow.

First we have red Cineraria, which for the sake of comparison
is prepared in the same way as the blue, and it is to this Jatter, as
compared with the former, that I wish to call your special atten-
tion. The spectrum, as will be seen on reference to Fig. 7,
differs from Fig. 4 in a notable degree; but as most present, no
doubt, recollect the inference our worthy President, in vol. xiii,
of our researches, drew between this colouring matter and that of
Lobelia speciosa, | need hardly pursue my investigation further, ag
the change here is almost identical, though the general absorption,

232 Transactions of the Royal Microscopical Society.

which to a degree is evident in the blue specimen, is entirely
wanting in the red. I annex the ratios of Mr. Sorby’s two read-
ings and my own, to show how nearly they agree, and Mr. Sorby
has since told me that his specimens were dissolved in a strong
solution of sugar, which quite accounts for the slight displacement

I have recorded.
Fic. 7.—Rep Crneraria.

)
M. A. | Observations.
|
1 | 22-95 | Centre =. «. 585° | Class 1. Ends shaded, centre dark;
size *5.

2 | 21°86 + aac 541° », 1. Same as No. 1; size *465.
Bi e2029> 45 a ee 499° », 1. Shaded evenly ; size -455.
Condition, A. Ae} |r A. Ratio.
Blue Cineraria.. 615: 575° 535° 490°1 9265
Red ¥, es 585° 541° 499° a 1 3. -9234
55 59 % 594° 550° 509° is £29258
Lobelia speciosa 619° 573° 529° DS 29257

There may, I think, be found in this alteration of colour some
similarity to the chemical effect caused in litmus, when that sub-
stance has, through the intervention of an acid or alkali, been
turned red or blue, as the case may be; and perhaps I may be per-
mitted to add that I have employed the spectroscope in many
cases where the determination of an acid or alkaline base has
been necessary in chemical analysis. A glance at Figs. 8, 9,
and 10 will suffice to show what takes place when the litmus is no
more alkaline or acid, as the case may be: the moment at which the
change occurs is the saturating point, and it is at times extremely
curious to observe the sort of conflict which takes place between
the two agents, till,.when subsidence occurs, we have either a
normal, acid, or alkaline result ; the only point necessary is, that the
original solution of litmus be made of a definite strength, and must
naturally represent the normal state; that employed in these ex-
periments is of 1 per cent.

Now this seems to imply that the red colour of a fresh plant is
more especially acid than the blue ; still the conditions of variation
are so exceedingly numerous, that to fix anything like a definite
why or wherefore as to the cause is quite out of the question, at
least so far as my own short experience of nature and natural
selection is concerned, I therefore must be pardoned if I shade
myself under the following extract, taken from Mr. Darwin's
admirable work, entitled ‘The Origin of Species.’ He there says:
“ When a variation is of the slightest use to any being, we cannot

Changes caused on the Spectrum, &e. By T. Palmer. 233

tell how much to attribute to the accumulative action of natural
selection, and how much to the definite action of the conditions of
life.” But to pursue the point somewhat further, and still to
keep to our author, Mr. Darwin, in his new work, under the
heading of “ Uniform colour of the flowers on plants self-fertilized,

22 el 20 19 Ey es a / 16 15 14 13

23

Fic. 8.

Litmus
normal.

=|

Fra. 10.

Litmus
ilkaline,

Fic. 8.—Lirmus NorMau.

M. | | A. Observations, °
21°3 Centre 25). 565°5 | Class 2. Very black.
20°7 indies cctin ats 509°0 | Shaded to this point; size 2:5.

Fic. 9,—Lirmvus Acrp.

21°2 Commencement a0} Shaded gradually to very black,
20°0 3 % 039°0 general absorption of blue, &c.

Fic. 10.—Lirmus ALKALINE.

|

some \e@entrel ss ia 570°0 ‘. : . pice .on
a Ta ee Re 5190 \ Same as in Fig. 8; size 2°25.

NRE

and grown under similar conditions for several generations.”
‘Time will not, however, permit me to give you his exact words,
but I should strongly advise all my hearers to invest in that charm-
ing book, which has now been out for some time, and is entitled
‘Cross and Self Fertilization of Plants.’ Mr. Darwin, after-having

234 Transactions of the Royal Microscopical Society.

quoted a few cases of experiments, performed with Mimulus luteus,
LIpomeea purpurea, Dianthus caryophyllus, and Petunia violacea,
says :—‘‘ These few cases seem to me to possess much interest. We
learn from them that new and slight shades of colour may be
quickly and firmly fixed, independently of any selection, if the
conditions are kept as nearly uniform as possible, and no inter-
crossing be permitted. With Mimulus, not only a grotesque style
of colouring, but a larger corolla and increased height of the whole
plant were thus fixed; whereas with most plants which have been
long cultivated for the flower garden, no character is more variable
than that of colour, excepting perhaps that of height. From the
consideration of these cases we may infer that the variability of
cultivated plants in the above respects is due, firstly, to their being
subjected to somewhat diversified conditions, and secondly, to their
being often intercrossed, as would follow from the free access of
insects.” “I,” says Mr. Darwin, ‘‘ do not see how this inference
can be avoided, as when the above plants were cultivated for several
generations, under closely similar conditions, and were intercrossed
in each generation, the colour of their flowers tended in some
degree to change, and to become uniform. When no intercrossing
with other plants of the same stock was allowed, that is, when the
flowers were fertilized with their own pollen in each generation,
their colour in the later generations became as uniform as that of
plants growing in a state of nature, accompanied at least m one
instance by much uniformity in the height of the plants. But in
saying that the diversified tints of the flowers on cultivated plants,
treated in the ordinary manner, are due to differences in the soil,
climate, &c., to which they are exposed, I do not wish to imply
that such variations are caused by these agencies in any more
direct manner than that in which the most diversified illnesses may
be said to be caused by exposure to cold. In both cases the con-
stitution of the being which is acted on is of preponderant im-
portance.”

In this last example, viz. Hypericene, I think you will see this
verified ; the juice obtained from Hypericum is, as you know, of a
reddish orange colour, turning red when treated with acid, but
retaining its natural colour to a certain extent when prepared with
oil. Our first spectrum, as shown in Fig. 11, represents this latter
form.

Fic. 11.—HYPERICENE IN OIL.

| M. A. Observations.
1 | D8. entros | 2.4 wa. 590° Class 1. Shaded; size °5.
2 | 21°55 os ao) 60 554° Same as No. 1; size °5.
3 | 19°00 | Commencement | 498- | General absorption.
|

Changes caused on the Spectrum, &e. By T. Palmer. 235

On examination it will be found to be not unlike that of red
Cineraria, though the blue end in this case is absorbed. I now
added a few drops of acid to the solution, stopping immediately
that the change of colour took place. This addition has, as will be
Seen on reference to Fig. 12, had a contrary effect on the first
two bands; they are, however, increased in definition, though their
shapes are of Class 2 or unsymmetrical, while in the case of
Fig. 11 they are of Class 1 or symmetrical, and the general ab-
sorption in Fig. 12 has advanced towards the red.

Fig. 12.—Hyprricense Actp.

M. | Ar. Observations.
Bsa Riek) Sa 8 .
l 22°92 | Centres a, see: aay Class 2. Very black, shaded to the
Peeks iy Bind v2 ai" §La0 |) S6b 5's right,
mec set | entre: .toeee || 4320 : ‘
2 { 90:2 Bates (et noe \ » 2. Black, shaded to the right.
3 | 20°6 | Commencement | 512:0 | General absorption.

Through the kindness of Mr. Sorby, whom I now take the
opportunity of most sincerely thanking, I am enabled to say that
the first of these two spectra is not the usual one given by the
colouring matter of normal hypericene. He lent me a tube of
pure hypericene, the spectrum of which nearly accorded with that
of my acid form, though the centres of the bands were different.
My first solution, Fig. 11, we are therefore inclined to think is due
to the presence of a yellow substance very common in plants, which
is made deeper by the addition of an alkali, and much paler by an
acid, in which latter case the intensity of the absorption would be
increased ; the effect of this is that my solution is yellower than
Mr. Sorby’s, and would be made more red by acid. Perhaps it
would interest you to know the coloured oil is not unlike that of
the solution in water, and like this has no fluorescence.

This example now closes my remarks. I think I have brought
suffiaent evidence, if not of proof, to substantiate what I have said,
at least enough to open up a field for an immense amount of
research. The conclusion which I draw from these few specimens
is, that any plant, colouring matter, or substance may be so acid
that the limit of the band of total absorption may be extended
beyond one’s vision into the violet, or that the contrary effect ma
be produced on the red by an alkali in excess. That both these
states may be present, and that they both may affect the spectrum
in their own particular way at the same time, is evident.

236 Transactions of the Royal Microscopical Society.

IIl.—Microscopic Aspects of Krupp’s Silicate Cotton.
By H. J. Stack, F.G.8., Sec. R.M.S.
(Read before the Royau Microscoricat Soctery, April 4, 1877.)
Pratrs CLXXX. anp CLXXXI. |

SizicaTE cotton is the name under which blast-furnace slag
reduced to a fibrous condition is now sold as a non-conducting
substance for covering steam boilers, pipes, ice-houses, safes, &e.
It is manufactured at the works of Herr Krupp, at Sayn, in
Germany, by forcing a blast of steam, water, or air through
molten slag, in the viscous state in which it runs from the furnace.

Having obtained a specimen through the kindness of Messrs.
Jones, Dade, and Co., the English agents, it was found when lightly
compressed to be much like cotton wool, but of finer fibre.
Amongst the fibres are to be seen a number of bulbs of various
forms and sizes, seldom, however, exceeding the magnitude of an
ordinary pin’s head, and usually less. The fibres vary in thick-
ness from that of common spun glass to an extreme tenuity repre-
sented by fractions of a thousandth of an inch. They are easily
blown about as a fine dust, and from their material, and forms,
as shown in some of the sketches, Figs. 1 to 4, must be very mis-
chievous if introduced into the lungs. It is said that special pre-
cautions have to be taken to prevent workmen engaged in the
manufacture from being seriously, or fatally, injured.

- The bulbs present some interesting appearances. They vary in
shape and size as Figs. 5 to 17 show, and also in internal structure,
though they may be generally described as solid bodies containing
more or less numerous vesicles and hollows.

Considering the sudden and violent explosive action by which
they are formed, little regularity might be expected in their
markings, but a considerable number exhibit a very beautiful
and symmetrical ornamentation. A spherule, for example, one-
thirtieth of an inch in diameter is thickly covered with compound
vesicles (see Fig. 18), consisting of a central clear glass film sur-
rounded by numerous minute bubbles, the whole when lit up under
the microscope having an elegant jewelled appearance.

When broken, the bulbs exhibit a conchoidal fracture diversified
with small cavities and vesicles. In some cases the symmetrical
arrangement last mentioned is found in the vesicles occupying the
centre of a bulb. In some spherules obtained from a Yorkshire
furnace by Mr. Sorby, numerous groups of crystals could be seen
composed of minute prisms arranged in rectangular patterns.

To test the mode in which such regular patterns as in Fig. 18
could be formed by explosive action upon a viscous substance, an

The Monthly Mierc
ee

|

x 300

| '
|
|
i

,

18

|

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i "Wiest Selo lth

Silicate Cotton bulbs.

Microscopie Aspects of Silicate Cotton. By H. J. Slack. 237

ounce or two of common rosin was melted in an iron ladle, and
when it began to boil suddenly thrown into cold water. An
irregular brittle mass was obtained, exhibiting here and there
small white patches. These when examined with 3-inch power
showed some compound vesicles like Fig. 18, and others as it were
in process of formation. It seemed as if the first action of the
explosive steam was to produce an immense number of minute
vesicles, and that those in the centre had a greater tendency to
coalesce than those at the margin. Some centres were composed of
a single clear vesicle, others of two, three, and so on.

The general character of the silica cotton threads is much like
the volcanic product known as “ Pele’s hair”; the bulbs resemble
volcanic bombs.

In some specimens the bulbs are like common white glass; in
others they glow with the iridescent tints of Venetian work, and
constitute objects of considerable beauty when illuminated with a
side silver reflector.

Iron slags producing this material are compounds of silica,
alumina, &c.

The following analysis from Percy’s ‘ Metallurgy’ may be taken
as an illustration of their composition. The specimen was from
South Staffordshire, and crystallized in well-defined translucent
square prisms * :

SHUIET ip? ok se eG pp ede ce LCOS
NOMINARy Osho. so ssha- sl) Gaee sce LAUT
IDTTIREN Rod as) Soles ote gas eo orl!
Miatonesine gag cas ea as se ea RSG
Protoxide of manganese .. .. .. 0°40
Protoxide of iron Se 0 ee as) ICH
Potash@ «as. tee a Ga ee Se OSD
Sulphide ofcaleium.. .. .. .. 0°82

99°81

The spun glass condition of slag is mentioned by Percy, who
says,t “owing to some accidental condition the melted slag has
actually been spun as it were by the blast, just as glass is spun by
a wheel. I have received beautiful specimens of this kind from my
friend Mr. Levick of the Blaina and Cwm Celyn Iron Works, and
also from Prussia.”

The fine threads of silicate cotton fuse readily into beads in
the flame of a spirit lamp, but they are unchanged by a full red
heat.

The substance is not a pleasant one to handle, and no doubt
numbers of sharp, and often curved and barbed particles entering the
skin would produce great irritation. On this account it is supplied

* Percy’s ‘ Metallurgy,’ vol. i. p. 23. t Ibid, p. 27.

238 Transactions of the Royal Microscopical Society.

in the form of mattresses 2} inches thick, made up ready for use.
Those who must handle it ought certainly to be provided with
thick gloves, and great care should be taken not to inhale its fine
dust.

The rapid cooling of this silicate cotton in its process of forma-
tion might be expected to give it polarizing properties, but it only
possesses them in a feeble degree.

TheMonthlyMicroseopical Journal Mayl.1877. lilt CLXXT.
|

( 239 )

TII.—On the Lower Silurian Lavas of Eycott Hill, Cumberland

By J. Currron Warp, Assoc. R.S.M., F.G.S., of Her Majesty's
Geological Survey.
(Read before the Royau Microscoricau Society, April 4, 1877.)
PLaTE CLXXXYVII.

CONTENTS.

Introduction.
1. Examination in the Field.
2. Microscopical Examination.
3. Chemical Examination.

Introduction.

Tue series of lavas which I propose to describe belong to the
northern extension of the volcanic series of Borrowdale, Cumber-
land. This series has been treated of in my memoir on the
Keswick district, and touched upon in various papers communi-
cated to the Geological Society. My object in the present paper
is to point out the value of microscopic research to the field-
geologist both from a practical and a theoretic point of view, and
at the same time to illustrate somewhat in detail the microscopic
structure of a fine succession of ancient Silurian lava-flows.

Eycott Hill lies in the north-eastern part of the Lake district,
just outside the range of the mountains, and a mile and a half
north of Troutbeck station on the line of railway from Penrith to
Keswick. The hill is often locally known by the name of Berrier
Nittles, and its highest point, through which the section (Plate
CLXXXII.) runs, is 1131 feet above the sea.

1. Hxamination in the Field.

The horizontal section, on the scale of six inches to a mile,
Plate CLXXXIL., shows the series now to be described, dipping at
a tolerably regular angle of from 35° to 40°. The interstratifica-
tion of a thin band of Skiddaw slate (No. 4), near the base, would
indicate that these are some of the lowest beds of the whole
volcanic series, and although at this particular spot the junction
between the Skiddaw slate and the volcanic rocks is a faulted one,
there is abundant evidence farther north (given in Survey Reports)
of the gradual passage from the one series into the other, or, in
other words, of the submarine character of the earlier volcanic
deposits, though at a later period the volcanoes became wholly or
almost wholly sub-aérial. Whether the entire thickness of more
than 2500 feet, shown in the section, represents submarine volcanic
deposits is doubtful; from analogy with other parts of the district
this is probably noé the case.

VOL. XVII. v

240 Transactions of the Royal Microscopical Society.

With the exception of four or five thin bands of bedded ash,
the whole thickness here given is made up of a succession of lava-
flows. The thickness of the highest bed of ash is uncertain, since the
ground is obscured by superficial deposits and the unconformably
overlapping carboniferous limestone soon hides any further suc-
cession eastwards.

It is not always easy to determine the thickness of the separate
lava-flows, though in many cases they differ somewhat in character
from each other, and are frequently highly vesicular in their upper
and lower portions. In some cases the vesicles have been most
markedly drawn out in the direction of flow. On the whole, the
varying character of the beds has given rise, by weathering, to a
general step-like form of the hill side, reminding one of the origin
of the word trap (¢appa, Swedish, a stair).

The ash varies in character from a very fine close fragmentary
rock to one made up of large angular fragments, and therefore
more properly called a breccia. The colour is often a fine purple,
though sometimes the finer ash has the same grey-blue colour as
the lava. The latter is also sometimes of a rich purple, but is
more generally some shade of green or dark blue. The various
lava-flows are of all degrees of texture, from a very compact flinty
rock to a finely crystalline and porphyritic one, in which the
crystals of plagioclase are sometimes an inch in length. The band
of Skiddaw slate interstratified among these lavas, and lying imme-
diately beneath a finely porphyritic flow, is not more than six or
eight feet thick, and is considerably hardened.

2. Microscopie Examination.

Perhaps the most satisfactory method of treating this part of
my subject will be to take the various beds in succession, as given
in the section, and describe the microscopic structure of each, where
necessary.

(1) Purple Ash.—This rock calls for no especial microscopic
notice, being clearly fragmentary, and sometimes coarsely so. Such
ashes when viewed under the microscope, in a thin slice, frequently
show broken crystals and fragments of lava or previously formed
ash-rocks imbedded in a fine dusty base, which last, under polarized
light, with crossed prisms, usually appears dark with scattered
points of light.

(2) Lava.—Lithologically this rock presents a compact green
base with yellowish or greenish tinge and small dark spots. It
probably represents more than one flow, as it is about 300 feet
thick, and has vesicular portions.

Microscopically, the base consists of a mesh-work of minute
felspar needles mingled with chlorite and magnetite, and a good

Lower Silurian Lavas of Eycott Hill. By J.C. Ward. 241

deal of quartz in cavities. There seems to be scarce any unaltered
augite, but, to judge from analogy, much of the chlorite must re-
present that mineral. Some of the green mineral has a trans-
versely fibrous structure when seen with crossed prisms.

(8) Skiddaw Slate Band.

(4) Lava (porphyritic) —This highly interesting and beautiful
bed is about 100 feet in thickness, and in lithological structure
shows a compact greenish-blue base containing dark-green spots of
a soft mineral, and large porphyritically imbedded felspar crystals,
many of them an inch long.

Its microscopic character I have already described in the
‘Keswick Memoir’ (p. 20), and in my paper on “The Microscopic
Structure of some Ancient and Modern Volcanic Rocks.” * In
both cases coloured drawings are given. That in the ‘Survey
Memoir,’ fig. 10, plate ii, shows a fine augite twin imbedded in
the base of acicular felspar prisms, the spaces between which are
filled up with a dirty green and brown pseudomorphic mineral
(chlorite and chlorophzite) and numerous crystals of magnetite.
The figure in the Quarterly Journal (fig. 6, pl. xvii.) shows a part
of the same more highly magnified, and that in the Plate illustrating
this paper (Fig. 1) shows the character of the crystalline base, one
of the green pseudomorphs, and a portion of one of the large
plagioclase crystals. These last are much cracked, and contain
glass cavities, portions of the base, and grains of magnetite; they
present very finely the banded structure peculiar to this group of
felspars when viewed with polarized light.

Augite, in crystals and grains, occurs pretty plentifully; much is
in the form of pseudomorphs however (the soft dark spots before
mentioned). The large twin spoken of above as figured else-
where, contains an interesting example of a glass cavity with a
bubble and two magnetite grains, with the following dimensions :

Glass cavity +525, of an inch in diameter.
Bubble =, of an inch in diameter.

Tao i 21 1 1 i
Magnetite grains the 3,5 and ~53¢5 Of au inch.

Some of the green pseudomorphs seem to be after olivine, pre-
senting the form and much-fissured appearance of that mineral. I
have detected grains of olivine in an unaltered condition in some of
these lavas, and therefore I think there can be no doubt that both
it and augite were common constituents at one time, though both
have been so much replaced by pseudomorphic minerals through
subsequent alteration. The top of this lava is beautifully vesicular
in parts, the vesicles being drawn out along the line of flow, and
filled with chlorite, chalcedony, and calcite.

* “Quart. Journ. Geol. Soc.’ vol. xxxi. p. 406.

7 2

242 Transactions of the Royal Microscopical Society.

(5) Ash (100 to 120 feet thick).—This bed serves as a good
instance of the value of microscopic examination. It is of so
fine-grained a texture that I had originally taken it to be one of
the more compact lava-flows, and had no suspicion of its ashy
character until examining it under the microscope together with
the other rocks in the same series. Unlike most of the fine ash-
beds it is free from bedding, and evidently consists of closely com-
pacted fine volcanic dust. Microscopic examination shows that the
fragments are pretty uniform in size, and that many consist of
lava.

Next above this ash comes a great thickness of lava-flows,
between 700 and 800 feet. They are numbered on the section
6 to 13. A little farther north than our line of section a band of
ash and breccia occurs among these flows, but dies out southwards.

(6) Lava.—Lithological: a very compact and dark base, with
small felspar crystals.

Microscopically the base is minutely crystalline, with small
felspar needles, very small magnetite grains, and disseminated
chloritic matter. Larger crystals of plagioclase felspar very much
altered. Very little unaltered augite. Some pseudomorphs, ap-
parently after olivine. ‘Small vesicles filled with calespar and
chlorite.

(7) Lava.—Lithological: compact greenish-grey base, with
small felspar crystals and dark spots; breaking with conchoidal
fracture.

The microscopic structure of this bed is shown in Fig. 2, Plate
CLXXXII. The base consists of the usual mesh-work of minute
felspar prisms with chlorite and magnetite, and in it are larger
imbedded crystals of felspar, all highly altered. There are many
chloritic pseudomorphs, but no unaltered augite.

(8) Lava.—tLithological: fine-grained base, with a reddish
tinge, and containing small crystals and spots.

Microscopical: a crystalline mixture of small felspar prisms and
small grains and crystals of altered augite (?), with sparsely scattered
magnetite. Some larger, but highly altered, felspar crystals, and
many small vesicles filled with chlorite and calcite and haying a
crystalline edging.

(9) Lava—A compact form.

(10) Lava.—Lithological: a compact greenish base, with
small felspar crystals.

Microscopical: fine crystalline base of felspar needles, mag-
netite, and chloritic (altered augitic) matter, with porphyritically
imbedded crystals of plagioclase felspar, and perhaps some ortho-
clase pseudomorphs, after augite and olivine.

(11) Lava.—-On the whole, similar to the preceding, but very
vesicular.

Lower Silurian Lavas of Eycott Hill. By J.C. Ward. 243

(12) Lava.—Lithological: purplish crystalline base, with many
small porphyritically imbedded crystals.

Microscopical: plagioclase crystals of various sizes imbedded in
minutely crystalline base. Magnetite and chlorite, and many
brownish-red specks of iron peroxide. Many of the larger crystals
of felspar, besides having numerous reddish specks and _ lines
scattered throughout them, are permeated by slender veins filled
with chlorite. Portions of the base are also sometimes enclosed (or
partially so) within the large crystals. No unaltered augite is dis-
cernible, but in other respects the general crystalline appearance is
quite that of the basaltic class of rocks.

For a chemical analysis of this rock, see p. 246, No. 3.

(13) Lava.—Lithological: compact dark-blue base.

Microscopical: consists wholly of a minutely crystalline mixture
of felspar needles, augite grains (a good deal altered), and mag-
netite, together with chlorite.

For a chemical analysis of this rock, see p. 246, No. 4.

A thin band of ash and breccia parts this thick series of lavas
just described from the following.

(14) Lava.—A vesicular form; small vesicles in a compact
greenish base.

(15) Lava.—Lithological: grey-blue and highly crystalline
base, slightly effervescing with acid.

Microscopical: highly crystalline ; plagioclase crystals from the
size of the ordinary needles up to those of + inch in length, show-
ing the banded structure remarkably well. The larger crystals
frequently enclose portions of the base. Magnetite, chlorite, and
calcareous matter disseminated.

For a chemical analysis of this rock, see p. 246, No. 5,

(16) Lava.—Much the same as the last.

(17) Lava.—Lithological: compact grey base, with small
obscurely-defined crystals and wavy reticulated lines.

Microscopically this is perhaps one of the most interesting
rocks of the whole series. ‘The base is minutely crystalline, in-
numerable small felspar needles all setting parallel to one another,
and having a well-marked flow around larger and porphyritically
imbedded crystals, much altered. Among the needles is much
chloritic matter, and magnetite in fine grains. The crystalline flow
is shown in plain light in Fig. 3, and under polarized light in
Fig. 4. There are also certain darker bands, roughly parallel to
one another, along which the chloritic matter seems to have been
converted into a dark-brown or reddish product; these bands
sometimes slightly cross the direction of flow.

In the example shown in Fig. 3, the porphyritically imbedded
plagioclase crystals often contain parts of the base enclosed within
them, and portions of their outline are very indistinct, with

244 Transactions of the Royal Micrescopical Society.

margins frequently indented by the base running far into the
crystals, The quantity of magnetite grains in this sliced specimen
is unusually large, and imparts a very dark character to the
base.

General Remarks on Microscopic Structure.

The examination of this series of lavas, and the lavas of the
district in general, proves conclusively that the minutely crystalline
base of small felspar needles is the prevalent form, though fre-
quently much obscured by subsequent alteration. These needles
are undoubtedly in many cases triclinic felspar, but in some they
may be orthoclase twins of the Carlsbad type. The larger crystals
are generally plagioclase, though orthoclase seems to occur some-
times. ‘They are replaced both by chlorite and serpentine, but
owing to the great number of pseudomorphs of green minerals
after both augite and felspar, it is by no means always easy—unless
distinctly aided by the crystalline form—to distinguish between the
various original constituents. Some of the chloritic pseudomorphs
have curious little yellowish granules disposed in irregular lines
along them, as seen in Fig. 2. In yet other cases the replacement
has been such that in polarized light the whole of the crystal
shows a mosaic of different colours, as seen in one case in Fig. 4.

The many examples in which the porphyritically imbedded
crystals either contain portions of the base shut up within them, or
show it running far into their sides, like inlets and bays, clearly
indicate that such crystals were formed previously to the consolida-
tion of the base. The frequent enclosure of grains of magnetite
within the glass cavities of the augite also points to the same fact,
and to the very early crystallization of the magnetite. Indeed, the
order of formation would seem to be, first the magnetite, next the
larger crystals of augite and felspar, and lastly the base, so largely
composed of minute needles of felspar, which frequently assume a
well-marked flow around the larger crystalline masses.

With regard to the augite crystals, it is striking how many
slices may be examined, and yet none but pseudomorphs after the
mineral be met with, while in other cases—though rather ex-
ceptional— most of the larger crystals appear almost unaltered, and
frequently exhibit well-marked twins. If this alteration be so
prevalent among the larger crystals, there is but little wonder that
the finer augitic matter which probably once existed throughout
the base, in many or most cases should have been all completely
changed, its place being taken by chloritic minerals. In Fig. 4
examples may be seen of partially altered augite crystals, under
polarized light.

The great quantity of pseudomorphic chloritic matter which
prevails among these old lavas entitles many of them to be classed

Lower Silurian Lavas of Eycott Hill. By J.C. Ward. 245

as diabases, and it becomes a question whether the term diabase
may not thus be best employed to denote a rock belonging to the
doleritic or basaltic class, in which the doleritie characters are much
obscured by the presence of chlorite, or its more unstable ally
delessite or chloropheite, changing to a brownish colour on ex-
posure. Zirkel remarks, under the head of diabase,* that the
diffused greenish mineral seems to be chlorite, and probably a
decomposition product of augite.

With regard to the accidental minerals, as they may be called,
of these ancient lavas, it should be remarked that excessive altera-
tion carried on through such exons of time could scarcely leave
them untouched, when the prevailing constituents have undergone
so much change; nevertheless both olivine and apatite may be
occasionally observed, and there are few characters common to
modern basalt which may not be recognized either in full or in
part among some of these ancient Lower Silurian lava-flows. It
now remains to be seen how far chemical analysis supports the
idea of the basaltic character of some of these rocks.

3. Chemical Examination.

Having previously had several analyses made of the lavas
occurring in the Keswick district, and found their composition to
agree with those of a generally intermediate group between the
basic and acidic series, I became anxious to test some of these more
northern lavas in the same way, and especially some of those which
both lithologically and microscopically appeared more truly basaltic
in character. I therefore selected three samples from the series
described in this paper, of varying texture and appearance, and
Mr. John Hughes, F.C.S., has made me the careful analyses which
will be found in the table on next page under the third, fourth,
and fifth columns. No. 3 analysis is that of the lava described as
(12) in our series, and is microporphyritic in character. No. 4 is
a very compact variety, and described as (13) in our section, and
No. 5 answers to (15), and igs more like a modern basalt both
lithologically, and in some respects microscopically, than any
others.

A comparison of these analyses with a mean analysis of rocks
of the doleritic class shows clearly a general correspondence, so that
chemically there can be no reason against considering some at any
rate of these old lavas as representing ancient basalts.

On comparing these three analyses with two of lava from the
Keswick neighbourhood, it is seen that the latter are markedly less
basic. In my previous papers I have stated my belief that many of
the old Cumberland lavas represent the intermediate group answer-

* *Mikroskopiche Beschaftenheit,’ p. 407.

246 Transactions of the Royal Microscopical Society.

ing to the modern “ greystones” of Scrope or trachy-dolerites, and
now I think there is equal reason to believe that at that very
remote geological period, the Lower Silurian, there were erupted some
lavas also of a basaltic type, and therefore that the idea formerly
held of the specific distinctness of the ancient from the modern
voleanic rocks is one that cannot be sustained. Mr. Allport has
already shown the specific identity of Carboniferous dolerites and
basalts with those of modern date, and I think that the microscopic,
chemical, and field evidence which I have been able to collect among
the volcanic rocks of the Lake district almost as clearly proves the
existence of doleritic and trachy-doleritic lavas among the Lower

Silurians. '
ANALYSES OF CUMBERLAND LAVAS.

(1) (2) (3) (4) (5) ‘
Brown | tron Cr ag Dolerite.
Knotts (Keswick Eycott Eycott Eycott Mean
Sortie District). Hill. Hill. Hill. Analysis.
Silica... .. .. «. | 60°718 | 59°511-| 53°300 | 52°600 | 51-100 | 51-00
Alumina .. .. .. | 14°894 | 17°460 | 20°990 | 17°315 | 22-051 | 16°06
OLA ies! ess ieee 2°354 | 3°705 °926 | 1°486 | 1-022 “84
Soda .. ; 2°843 | 3°093 | 2°456 | 2-622) 2-216 2°66
1 LTC Le rae Pe Oe 6°048 | 5°376 | 8°512 | 7-728 | 11:424 9°53
Magnesia... <5 0% 1:909 |} 1°801 | 3°964 | 3°252 | 2°346 5°18
Ferrous oxide .. 6°426 | 4°926 | 6°343 | 12-043} 5-885 14°75
Ferric oxide .. .. | 1°405 | 1°271| 1:°660| 1°722| 1-210 \ ?
Bisulphide of iron .. *395 “604
Phosphoric acid ., "281 "115 *102 +153 “179
Subphuricacid.. .. 103 "086 | trace trace trace
Carbonic acid .. .. 1-660 | 1°569 *320 -140 | 1:°820
Loss on ignition .. 964 °483 | 1-120} 1-160 -710 1-42

100°000 |100°000 |£00-000 |100-000 |100-000

Nos. 1 and 2 have been already published in the memoir on the Keswick dis-
trict (sheet 101 8. E). Nos. 3, 4, and 5 are new, and unpublished in any paper
or memoir.

7
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The Monthly Microscopical Journal, May 1.1877

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( 247 )

IV.—The Modifications which the Egg of the | Hooded-eyed|
~ Medusa undergoes before Fecundation. By M. A. Grarp.

WE may take as a type the egg of Rhizostoma Cuviert. This
medusa is found in great abundance, during autumn, along the
shore of Wimereux, along with Chrysaora hyoscella and some
other Acalephs.

The smallest eggs in the ovary are formed of a transparent
vitellus, enclosing a germinal vesicle and a nucleolus. One does
not recognize any enveloping membrane at this stage. In pro-
portion as the ovum increases in size, its transparency diminishes.
The vitellus is charged with deutoplasm, and the germinal vesicle
becomes more indistinct; at the same time one may distinguish on
the periphery a very delicate vitelline membrane closely applied
,against the vitellus. At a further stage the egg presents on its
surface a series of spherules equally spread over the whole. These
are filled with a perfectly transparent substance, and are separated
from the external membrane by a thin layer of granular proto-
plasm, identical with that which occupies the centre and covers
over the germinal vesicle. An optical section of the egg may then
be compared roughly with that of a young vegetable stem at the
moment the first circle of vascular bundles appears, which then
divides the parenchyma into three parts: one central, one peri-
pheral, and a third radial, uniting the two. The hyaline spherules
rapidly increase till they touch each other, and at the same. time
they attack the vitellne membrane. With a slight magnification
it seems as if the vitellus was surrounded by a layer of cells which
projected from its surface at right angles. More highly magnified
one sees that the central granular protoplasmic mass is connected
with the vitelline membrane by an immense series of little columns
widened at both their extremities like the stalactitic columns we
sometimes find in a cavern, uniting the two masses of stalagmite,
that of the ceiling and that of the floor. These columns are con-
stituted of a protoplasm less granular than that of the interior of
the ovum. Finally, at the moment when the egg arrives at matu-
rity, the columns break and leave only very slight thicknesses of
the vitelline membrane at their former points of attachment. Then
we have a central granular mass in which the germinal vesicle is
not directly observable, and around this mass a transparent zone,
which separates it from the vitelline membrane.

Professor Harting has seen in the eggs of Cyanea Lamarekii
and C. capillata the stage in which the columns appear,* but not

* Harting, “Notices Zoologiques” (‘ Niederlandisches Archiv,’ Band [r,
Heft IIL).

248 Modifications in Egg of the Medusa, &c. By M. A. Giard.

having completely followed the preliminary phases he has given a
false interpretation of the appearances observed. He considered
that the ova of Cyanea were provided with a vitelline membrane of
a considerable thickness, and pierced by a very large number of
pores leading from without inwards, such, said he, as we find in
the ovum of certain mammals—perhaps in all—and also in the
ovum of many Teleostean fishes, where these pores have a much
more considerable dimension. It is evident that these pretended
pores are nothing else than columns of a clearer protoplasm to
which we have already referred. Thus equally fall to the ground
Harting’s supposition regarding the physiological function of these
pores, that they may serve as channels for the respiration of the
ovum, and also perhaps for the passage of the spermatozoa
inwards.

The preceding observations were conducted at Wimereux during
September 1875. They were part of a series of researches not
yet completed on the development of Medusz, and I decided to”
publish them now because they seem to me to acquire a generality
and an importance much greater than I at first supposed, thanks to
the magnificent investigations of Weismann upon the ovum of the
Daphnoidz (Clodocera).*

Weismann has observed a process very like that which we have
described, in the formation of what he calls the shell (schale) of the
winter egg, in the genera Polyphemus Sida and Daphnella. It
is remarkable that in this case, as in that of the Meduse, the egg
underwent a tolerably long incubation in a special medium fur-
nished by the maternal organism.

The excretion of hyaline vesicles, which takes place from the
entire surface of the vitellus in the ovum of Rhizostoma, may in
other animals be limited to a portion of the surface. The pheno-
menon then will have the appearance of a sort of excreted globules.
One may—in the presence of this process—ask if the phenomena
frequently pointed out, of rejection of a certain part of the vitellus
at the moment of the maturation of the egg, should be regarded
as equivalents in all animals in which they have been observed.
Biitschli has in the clearest manner shown that the corpuscles de
direction of the egg of Lymnzxus, Succinea, Nephelis vulgaris,
and of Cucullanus elegans, arise by the process of cellular division.
I may add that it is the same in Sulmacina Dysteri and in
Spirorbis. In these various animals the excreted corpuscles have
the value of rudimentary cells, having an atavic signification, and
cannot be suitably styled refuse corpuscles (corpuscles de rebut).
This term may, on the other hand, be applied to non-cellular

* Weismann, “ Zur Naturgesch. der Daphnoiden” (‘ Zeitschrift fiir Wiss.
Zoologie,’ XX VILL. Band, 1 and 2 Heft).

Modifications in Egg of the Medusa, &c. By M.A. Giard. 249

materials, which, rejected by the vitellus, serve in the formation of
accessory organs of the egg, for example of the shell (a coque) or
the vitelline membrane. Such are the hyaline vesicles of the ovum
of Rhizostoma Cuvieri.

Errata in the President’s Address.—At page 129, in the bottom line, for orthoclase
read oligoclase. At page 130, in the second line from the top, for abite read albite,
and for oligoclase read orthoclase. At page 134, in second line from bottom, omit
the words of gypsum.

( 250 )

PROGRESS OF MICROSCOPICAL SCIENCE.

" Recent Researches on Kélliker’s Dieyema.—Professor Van Beneden
has made some very important researches recently on the peculiar
worms that bear the above name, and which appear to be parasitic on
the renal (?) organs of various Cephalopods. These researches have
been fully reported by (we suppose) the. younger Packard in the
‘American Naturalist. He says that Van Beneden claims of these
species that they have no general body-cavity. The body is formed
(1) of a large axial cylindrical or fusiform cell, which extends from
the anterior extremity of the body, enlarged into a head, to the caudal
extremity ; (2) of a single row of flat cells forming around the axial
cell a sort of simple pavement epithelium. All these cells are placed
in juxtaposition like the constituent elements of a vegetable tissue.
There is no trace of a homogeneous layer, of connective tissue, of
muscular fibre, of nervous elements, nor of intercellular substance.
There is only between the cells a homogeneous substance, as between
epithelial cells. The axial cell is regarded as homologous with the
endoderm of the higher animals. He designates as the ectodermic
layer the cells surrounding the large, single axial cell. There exists
no trace of a middle layer of cells. We discover no differentiated
apparatus; all the animal and vegetative functions are accomplished
by the activity of the ectodermic cells and of the axial cell. On
account of these characteristics Van Beneden regards these organisms
as forming the type of a new branch of the animal kingdom which he
distinguishes as Mesozoa. Hach species of Dicyema comprises two
sorts of individuals differing externally, one (the Nemuatogene) pro-
ducing vermiform embryos, the other (Rhombogene) infusoriform
young. The Nematogenes produce germs which undergo total seg-
mentation, and assume a gastrula condition. After the closure of the
blastopore the body elongates, and the worm-like form of the adult is
finally attained, as they pass through the body-walls of the parent.
The germs of the Rhombogenes arise endogenously in special cells
lodged in the axial cell and called “germigenes.’ The germ-like
cells undergo segmentation, and then form small spheres which
become infusoriform embryos. The worm-like young is destined to
be developed and live in the Cephalopod where it has been born,
while the infusorian-like young probably performs the office of dis-
seminating the species; it transmits the parasite of one Cephalopod to
another. This work is also an important contribution to histology,
particularly to the subject of cell-division. Says Van Beneden, “ the
recent researches of Auerbach, of Biitschli, of Strasburger, of Hert-
wich, and those that I have published, have established the fact that
the division of a cellule, that is to say, the multiplication of the cellular
individuality, is the resultant of a long series of complex phenomena,
accomplished in a determinate order, and having their seat as much in
the nucleus as in the substance of the cell.” Finally, Van Beneden
places in his branch of Mesozoa the hypothetical Gastreades, which

PROGRESS OF MICROSCOPICAL SCIENCE, 251

term he applies to (gastrula-like) organisms formed of two kinds of
cellules, some ectodermic, others endodermic, in which the endoderm
is formed by invagination. He calls Planulades, those hypothetical
Mesozoa which are formed from a many-celled sphere constituted like
a Magosphera (Haeckel) and in which the two cellular layers are
developed by delamination. He therefore divides the animal kingdom
into three primary groups, that is, the Protozoa, the Mesozoa, and the
Metazoa. i

A curious New Sponge, Kallispongia.—Professor E. Perceval Wright
describes * a beautiful little sponge found growing on the fronds of
some species of red seaweeds from the coasts of Australia. _ The
largest specimens measure not three millimeters in height. The
sponge consists of three distinct and well-marked portions: firstly, a
small basal disk; secondly, an elongated stem, on the summit -of
which expands the third portion, or capitulum. The disk is button-
shaped, flat, and is formed of an irregular horny framework, twice to
three times as broad as the stem. The stem varies in height, and
presents the appearance, in some cases, of a series of margined rings,
some twenty in number, fastened together one on the top of the other;
in others the margins of the rings will be more prominent, and the
bodies of the rings will be, as it were, more deeply sunk. In both
these cases the horny framework is of a more or less evenly latticed
character, the longitudinal lines of the lattice being very prominent.
The head portion, in its natural state, probably presents a more or less
spherical form, perhaps slightly flattened on the summit, with an in-
dication of being divided into four nearly equal parts, the open space
between these leading into the body-cavity of the sponge. In some of
the specimens the head portion nearest to the stem seems to have been
formed of a somewhat denser framework than the upper portion, so
that while being pressed this upper portion has been fractured across.
The framework here is of a densely reticulated kind, in appearance
reminding one of the reticulated network of the intracapsular sarcode
in Thalassolampe, or of the tissues met with in some Echinoderms.
This sponge has been called Kallispongia Archeri. The wonderful
mimetic resemblance which it bears to some Crinoid forms can
scarcely be overlooked. Leaving the texture and composition of the
skeleton mass for the moment out of view, and simply looking at its
outline—the circular disk-like base, the stem—the profile of which is
absolutely the same, except as to size, as that of the pentacrinoid stage
of Antedon rosaceus, and the slightly cleft head, the resemblance is
very great.

The Microscopic Anatomy of Vaccination.—Messrs. Braidwood and
Vacher have published a very lengthy report on this subject in the
‘British Medical Journal.’ In this they state the following con-
clusions :—a. The principal local changes excited by the vaccine
contagium affect the rete mucosum, and consequently the hair-
follicles. 6b. They consist in corpuscular infiltration of this tissue.
c. The corpuscles to be most distinctly seen during the earlier days

* ¢ Proc. R. Irish Acad.’ vol. ii. ser. 2, part 7.

252 PROGRESS OF MICROSCOPICAL SCIENCE.

after inoculation, infiltrating this tissue, are oval or round nucleated
cclls, deeply tinged by carmine. d. On successive days, these cor-
puscles are to be seen in the crypts or hair-follicles budding or
throwing off minute, round, highly refractive bodies. e. During the
later stages, when the pock has nearly matured, these corpuscles
elongate into fibres, or shrink up. jf. In becoming fibres, they
encroach on the hair-shafts and hair-follicles. In none of the pre-
parations examined by us have we observed any bacteria, fungoid
forms, or allied organisms.

Dr. Klein’s Observation on Small-pox.—We regret that this has
not been noticed earlier, but it is of so much importance that we
cannot allow it to remain absolutely nnnoticed. It is this. Dr. Klein
has been convinced by Dr. Charles Creighton that his observations
published in the ‘ Philosophical Transactions’ (vol. 165, part 1) are
in part incorrect. He there described certain structures in the
lymphatics of the skin as the mycelium of a fungus which he termed
Oidium variole. He has, since Dr. Creighton published his paper, re-
called his former observations. With an honesty of purpose for which
it is hard to praise him too much, Dr. Klein says:—“ A comparison
of the two kinds of specimens convinced me that the appearances re-
presented in my figs. 18 and 19 are not due, as I supposed, to a
mycelium in the cavities of the primary pustules, but are products of
coagulation of some albuminous or kindred material by the reagent
that had been employed for hardening the object in question (dilute
chromic acid and spirit). The vegetable nature of the other structures
—viz. those represented in figs. 9, 10, and 11 (i.e. the supposed
mycelium in the lymphatics of the skin of the pock), as well as those
in figs. 16 and 17 (i. e. the mycelium in the cavities of the secondary
pustules)—becomes therefore very doubtful. My doubt as to these
being also produced by coagulation is based partly on the similarity
between the last-named features and those undoubtedly non-vegetable
objects in Dr. Creighton’s specimens and also in my figs. 18 and 19,
and partly on the following circumstances :—(1) I have lately ascer-
tained that blood, especially in febrile conditions, which is contained
in blood-vessels of tissues that had been subjected, in a fresh con-
dition, to the hardening fluid (e. g.c hromic acid), presents appearances
very similar to branched mycei:ium-threads to which are attached
numerous conidia; the presence of more or less unaltered blood-
corpuscles proves their true character. (2) I have likewise seen that
blood-plasma containing globulin or parts of blood-corpuscles, when
in lymphatic vessels or kindred spaces, show sometimes in the course
of coagulation similar appearances. Whether the greater number of
the thread-like structures is due to fibrin or to blood-corpuscles I
cannot determine as yet; but it seems to me that both is the case.”

Mr. Sorby on the Red Clays of the Ocean-bottom.—The President of
the Royal Society, in his late address, makes the following observa-
tions on this subject :—‘“ Before leaving this subject, I must mention
the endeavour of our Fellow, Mr. Sorby, to determine the nature of
the Red Clays of the ocean-bottom, of which we have heard so much.

PROGRESS OF MICROSCOPICAL SCIENCE. 253

He informs me that, though any conclusions now to be drawn from his
observations must be provisional, it is safe to consider that many
specimens of the Red Clay are so entirely analogous to what the
Gault must originally have been, that those specimens might almost
be looked upon as being as truly modern Gault as the Globigerina-ooze
is modern Chalk. In the Gault the grains of fine sand are chiefly
quartz derived from the decomposition of schistose rocks. But the
Pacific and Atlantic muds from great depths contain, besides quartz
fragments, others of glassy felspar, pumice, and other volcanic pro-
ducts; and Mr. Sorby has not been able to detect any difference
between the main mass of the Gault and other rocks which are com-
posed of very minute granules like those derived from felspar or other
minerals which, in a similar manner, easily undergo complete chemical
decomposition. Independent, therefore, of the presence of different
organic remains, and of the modern volcanic products, there is little or
no difference between the Red-Clay deposits and some of the earlier
stratified rocks.”

Empusca musce.—On this subject a paper was lately read before
the Quekett Club, and appears in the last number of the Journal,
by Mr. T. Charters White. He said, among other things, that the
characteristic appearance of a fly affected with this disease is best
detected when the fly, in its last moments, settles on a window; it
then may be recognized by a zone of white deposit surrounding the
fly like a halo—the fly maintains its living attitude, and will be found
attached solely by the lips of its proboscis. Its legs are not crossed
under it as is the case with all dead insects, but distended, as in the
live state. Examining the fly now externally, you will find the hairs
covered with minute white globules. These are the spores of the
fungus, and are scattered also round the fly for some distance, in a
very curious manner; in some cases almost as if they had been
squirted out of regular points of the body. ‘The abdominal rings are
separated by about their own breadth from each other, while they seem
bursting from over-distension. 'The thorax and head do not seem so
much affected as the abdomen. On opening the fly in a little glycerine
and water, the cause of this over-distension is soon discovered by the
appearance of a dense mass of mycelium threads, that emerge as soon
as an opening is made in the abdomen, On the termination of Mr,
White’s paper, a few very sensible observations on it were made by
Mr. W. W. Reeves, which we quote as follows. He suggested that
Mr. White might have carried the subject further with greater ad-
vantage, for if they wished to follow up the growth of this fungus
they must not be content merely to watch it as found upon dead flies,
this being only half its history. Let them drop the fly into water,
and then see what would take place. In a short time they would see
the fungus grow out and develop in a very beautiful manner. It never
fully developed upon a window pane for want of sufficient moisture,
but if this were supplied much more could be seen of its history.
Very little was known about it, but if anyone wanted to become
better acquainted with it, by placing a fly thus attacked in a little
water its further growth might be readily studied. Like many of this

254 PROGRESS OF MICROSCOPICAL SCIENCE.

class of fungi it assumed different forms under different cireum-
stances. It might be that the fly got into a diseased state, and
settled upon the moist window pane—for it was only to be observed
in damp weather. In the fifth volume of the ‘Quarterly Journal of
Microscopical Science,’ p. 154, some account of it would be found ;
and in vol. iii. p. 55, of the early Transactions of the Microscopical
Society, it was described and figured by Mr. Cornelius Varley. Mr.
Reeves added that the fungus was not confined to the house-fly—it
was found also on the blow-fly and several other insects.

Early Development of Sponges.—In a recent report of a meeting of
the Société Vaudoise des Sciences Naturelles, ‘ Nature’ says that Pro-
fessor Forel spoke on an interesting occurrence of an early develop-
ment of sponges in the Lake of Geneva, due to the unusually mild
winter of this year. The fluviatile sponge of the lake consists of
a horny skeleton with very fine siliceous spiculs, covered with a
sheet of soft, perforated animal matter. Usually, in autumn, this
soft matter leaves the exterior ramifications and condenses under the
form of small gemmule, half a millimeter in diameter, in the deepest
interior parts of the horny skeleton. There it remains until the
spring, when it expands anew upon the ramifications, and covers them
with a sheet of living animal matter. But this year M. Forel observed
on February 2, besides many sponges in their hibernal state, a colony
of other sponges which had already reached their full summer de-
velopment, differing only by a somewhat paler colour from the usual
summer appearance. The occurrence is perfectly explained by the
circumstance that the temperature of water in the Lake of Geneva was
this year higher by two degrees than the average temperature for
many years, which is 6°°3 Cels. for December and 4°°9 for January.

The Structure of Itacolumite has been recently described to the
Academy of Natural Sciences of Philadelphia,* by Professor W. P.
Blake. The specimens, which were obtained in California, were un-
usually fine, some being over 30 inches in length, and only 2 square
inches in section. The colour and the structure appear to be the
same as in flexible sandstone from other localities.. Thin and
small scales of silver mica are abundant. It bends with little re-
sistance up to a certain point, and without elasticity, but is rigid
beyond that point. When held up by one end and shaken, the motion
is transmitted in wave-like vibrations as in a cord, but the limit of
movement is sensibly felt like a blow or shock. A specimen 32
inches in length may be bent 73 inches to one side or the other of
a straight line. The freedom of movement is greatest at right angles
to the plane of lamination. The specimens are also capable of being
sensibly extended when pulled. In a specimen 82 inches long the
extension amounted to about half an inch. The freedom of movement
up to a certain point and the rigidity beyond that point indicate that
there is a tolerably uniform distance between the grains of sand and a
certain amount of movement possible among them, and that by bend-
ing, the grains are brought into contact with each other. The theory

* December 3, 1876,

PROGRESS OF MICROSCOPICAL SCIENCE. 255

of the late Professor C. M. Wetherill that the grains of sand are
shaped like dumb-bells was referred to with a doubt of its correct-
nes. The part which the scales of mica play can only be shown by
the examination under a microscope of carefully ground sections of
the stone, which might perhaps be prepared for cutting by solutions
of soluble glass. On concluding his remarks, Professor Blake was
followed by Professor Leidy, who stated that he had examined Itacolu-
mite microscopically without being able to detect anything like the
dumb-bell structure described by Dr. Wetherill. He supposed that
the intermingling of grains, differing in translucency and colour, gave
rise to the impression of a dumb-bell arrangement. Thus a pair of
adherent translucent grains surrounded with smaller coloured ones
would give rise to such an impression.

Circulation in a Fungus.—Mr. A. Lister recently exhibited a very
interesting microscopic object at the Linnean Society. It was a bit of
a lowly organized fungus known as Oldhamia utricularis, and there
was seen to be a definite current running along spaces which had
certainly the appearance of vessels. This current was of a clearish
liquid, having numerous corpuscular elements in it. It was kept up
for a considerable space of time. Mr. Lister promised to exhibit it at
the Royal Microscopical Society, but unfortunately the approach of
cold weather absolutely destroyed it.

Botanischer Jahresbericht—We learn that the first part of the third
volume of this admirable work has appeared, and we take this oppor-
tunity of recording the fact. We received the two earlier volumes
some years since, and we have found them very valuable résumés of
the work done in previous years, not only in general botany, but in
physiological and microscopical work.

The Reproduction of Ulothrix zonata.—An important memoir of
considerable length has been published on this subject in ‘ Prings-
heim’s Jahrbiicher’ (vol. x. part 4), by Dr. Arnold Dodel, and there
is an abstract of it as follows in ‘Silliman’s Journal’ for February.
The genus Ulothrix belongs to the order Zoosporez, in which the re-
production takes place by means of the macrozoospores and micro-
zoospores, the former having four cilia and one germinative spot (the
name given to the reddish-coloured dot found on one side), the latter
having only two. The former bodies have for some time been con-
sidered non-sexual, while the latter have been supposed to represent
sexual organs which by their union form a body with four cilia, and
distinguished from the macrozoospores by having two germinative
spots instead of one. This body, which is called the zygospore, cor-_
responds to the organ of the same name in the Desmidez and Con-
jugate proper. Dodel confirms the views of Areschoug, Cramer, and
others, that the macrozoospores do not conjugate, but, after losing
their cilia and coming to rest, grow at once into a new plant. He also
agrees, in the main, with Areschoug as to the conjugation of the
microzoospores, aud besides has been able to give a more exact ac-
count of what becomes of the zygospores. He finds that they remain
for a considerable time unchanged, and finally divide into a number

VOL. XVII. U

256 PROGRESS OF MICROSCOPICAL SCIENCE.

of zoospores, which soon come to rest and grow into new plants, as
in the case of the macrozoospores. The latter it appears are more
common in winter and spring, and were produced abundantly on
thawing tufts which had been frozen, while the microzoospores are
more common in summer. The most curious fact observed by Dodel
is that those microzoospores which, for any reason, do not succeed
in conjugating, grow at once into new plants just as in the case of
the macrozoospores. In other words, the sexual process is reduced to
the direct union of two bodies so similar that it is impossible to dis-
tinguish one as male and the other as female, and furthermore these
bodies, if not placed in conditions favourable for conjugating, can at
once grow into new plants. It would be difficult to find sexuality of
a lower grade than this, where each sexual organ is also capable of re-
producing the plant by non-sexual growth. We would recall the case
of Eurotium herbariorum mentioned by De Bary, where, of the several
male organs (pollinodia) only one succeeds in coming in contact with
the female organ, yet all, after the fertilization has taken place,
continue to grow and take part in the formation of the sac which
eventually encloses the spores. With very rare exceptions in the
Thallogens, the male organ at once atrophies after fertilization has
been accomplished.

A New Parasitic Green Alga.— Nature, of March 8, says that not
very long since it was thought that the want of chlorophyll deter-
mined the parasitism of plants, and it is still true that the want of
this green colouring substance serves to distinguish between fungi
and alge. It is also true that the former need already-formed carbon
compounds, but it is still thought that chlorophyll-bearing plants not
only do not require to find these compounds ready formed, but that
they are absolutely unable to assimilate them. It was therefore a fact
of great interest when Professor Cohn described some years since
(1872) a perfectly new chlorophyllaceous alga,* which he found
living as a bright emerald green parasite in the thallus of duck-weed
gathered at Breslau. For this the genus Chlorochytrium was esta-
blished, and C. lemne was the only species until at a late meeting of
the Dublin Microscopical Club, Professor E. Perceval Wright ex-
hibited and described a second species found growing and developing
itself in the mucilaginous tubes of a species of Schizonema, collected
on rocks at Howth, near Dublin, between high and low water marks.
There can be no question as to the parasite on the diatom bein
different from that on the duck-weed, while there is but little difficulty
in placing it in Cohn’s genus. Smaller in size its emerald lustre is
scarcely if at all less than the fresh-water species, and like it its
development has not been traced farther than the production of
ZOOSpores.

The Structure of Distoma sinense.—This is very fully given in a
paper by Dr. W. Macgregor, of Fiji, which appears in the ‘ Glasgow
Medical Journal’ (January 1877), and to which is appended a note by

* “ Ueber parasitische Algen,” in ‘ Beit. zur Biol. der Pflanzen,’ Bd. I. Heft 2.

PROGRESS OF MICROSCOPICAL SCIENCE. ZT

Dr. Spencer Cobbold, fully confirming the author’s views. There is an
excellent plate too, representing the natural size (half-inch), and
also showing its minute anatomy, of which the following is an
abstract :—1. Oral extremity. There is a deep, circular, cup-shaped
cavity, having the proper opening of the mouth at its base. From
the mouth proceeds a tube that dilates almost immediately to form a
pharynx, directly beyond which the tube bifurcates, sending a division
along each side to the caudal extremity, where they terminate in
ceecal ends without any branching or subdivision. These tubes are
no doubt the stomach. The contents are small, granular, usually
refractive particles. 3. The water-vascular system. It commences
at the extremity of the broad or caudal end, and after coming nearly
in a line with the blind extremities of the stomach tubes, it dilates a
little, and proceeds onwards in a slightly crooked course as far as
nearly one-third the length of the animal. It then divides into two
branches, which proceed one to each side until they traverse the
stomach tubes, when they subdivide into two branches, one of which
proceeds forwards and the other backwards, just external to the
stomach. The contents are small, highly refractive particles. The
organs concerned in reproduction occupy the greater part of the
animal. 4. The ovary —a dark oval-shaped body lying obliquely
with regard to the long axis of the parasite, and almost entirely to
one side of the median line, from a little beyond which it extends to
the stomach tube. It varies in size and shape according to the
quantity of its contents. Attached to its end next to the oral extremity
of the animal, is an irregular saculated pouch. It would appear to
retain the miniature eggs until they are sufficiently developed for
extrusion into the uterus. 6. Ducts of the yelk-forming glands.
They proceed straight from the uterine pouch one to each side of the
animal, and spread out into two beautifully formed bodies, the yelk-
forming glands, situated between the stomach tube and the outer
edge of the animal, on both sides, as far forwards as the neutral
acetabulum and as far backwards as the ovary. Their contents are of
a dark brown, but after being treated for some time with a solution
of caustic soda, they become of a light red colour. 8. The uterus.
A long irregularly branched tube occupying nearly the whole space
between the gastric tubes from the uterine pouch behind to the
neutral sucker in front. In every specimen it has a dark brown
colour from the multitudes of contained eggs. It opens externally
upon the surface of a small papilla. 10. The two testes. They are
situated the one behind the other in the posterior third of the animal.
They present a beautiful dendritic appearance that varies in its
details of form in different individuals. It is very difficult to trace
the course of the vasa deferentia. They seem to form a common duct,
the end of which is modified to serve as an intromittant organ; but
my observations on this point are not quite satisfactory. The eggs
are very small; they have a brown colour, which is due not to the
shell or covering of the egg, but to the yelk-granules. The operculum
of the egg is colourless. It is situated at one end of the egg, and
seems to be easily detached, as it is not seen on many eggs, even

u 2

258 PROGRESS OF MICROSCOPICAL SCIENCE.

before extrusion from the uterus. The secretions of the ovary, testes,
and yelk-glands seem to meet in the uterine pouch, and to form
by their union a fully developed egg, which passes thence into the
uterus. The outer covering of the animal has a tuberculated appear-
ance under the microscope, but has no cellular formation.

Microscopic Changes in the Brain of the Insane-—This is not a
subj:ct from which we can hope for much results at present. Still it
is necessary to record any results that are arrived at. Therefore a
paper that originally appeared in the ‘Dublin Journal of Medical
Science, and which has been abstracted in the ‘Medical Record’
(March 15, 1877), is of interest. The author, Dr. Atkins, after
referring to the elementary histology of the cortex of the brain, em-
braces under three heads the morbid changes he observed in insanity,
affecting—Ilst, the nerve-cells; 2nd, the neurogla; 3rd, the nerve-
fibres. With regard to the former, the writer first alludes to the
fuscous degeneration, and apparently does not hesitate to regard it as
identical in its nature with the fatty degeneration of Blandford, and
the granular degeneration of Major. The stages of pathogenesis are
grouped under the heads of infiltration, precipitation, and disintegra-
tion. The chemical nature of the change is regarded as pigmentary
rather than fatty. To the pathology of simple atrophy Dr. Atkins
adds nothing fresh, and he does not appear to appreciate the fact that
the so-called “ giant-cells” are found, when searched for, in all brains.
Under the morbid changes of the neuroglia, the coarse fibrillar ap-
pearance seen often in epilepsy is regarded as a form of sclerosis.
Disseminated and miliary sclerosis are then dealt with, and the pre-
sence of colloid and amyloid bodies referred to. With regard to the
nerve-fibres, Dr. Atkins appears dubious upon the significance of
appearance, which (from his description) must be regarded as the
varicose condition artificially produced, and which certainly does
not approach the description of Mr. Hamilton’s artificially induced
myelitis.

The Circulatory System in Magelona.—The anatomy of this curious
annelid has been gone into very carefully by Dr. McIntosh, who says
of the circulatory system that the blood is a densely corpusculated
fluid, the corpuscles having a pinkish colour. There are two large
dorsal vessels which arise, near the tip of the tail, from the bifurca-
tion of the ventral trunk. They pass forward along the dorsal arch
of the alimentary canal, receiving in each segment a large branch
from the ventral trunk and numerous capillaries from the intestinal
wall, until the posterior border of the tenth segment is reached. At
this part their dilated walls are supplied with powerful muscles,
which, on the relaxation of the great muscles of the ninth segment,
enable them to perform the functions of contractile chambers or
“hearts,” and by vigorous systole send the blood forward in a swift
stream along the single dorsal vessel of the anterior region. On
arriving at the base of the snout the vessel ends in the efferent branch
to the tentacle on each side. The current rushes along the latter
(nearly at right angles to the dorsal trunk) to the tips, sending off in

_

—— a a ee

PROGRESS OF MICROSCOPICAL SCIENCE. 259

each a web of circumferential capillaries throughout the greater part
of its length, and terminating in the afferent vessel, which proceeds
backward, collecting, as it goes, the capillary streams, and then ends
by turning forward at the base of the snout as the efferent cephalic
vessel. The latter has no evident capillaries, but bends round at the
tip of the flattened organ to terminate in the afferent cephalic vessel.
A curious change takes. place in the majority of those Magelons
which are provided with convoluted lateral organs of the body, in
autumn. The cephalic vessels are much abbreviated, and the direc-
tion of the current at the base of the snout is somewhat modified.
The blood from the head and anterior region collects into a series of
large vascular meshes which occur in the anterior region of the body,
and in which the current is for the most part under the control of the
greatly developed muscles of the body-wali. Thus it happens that
the contraction of the latter, and of the special muscular apparatus
which closes the communication with the posterior region at the
ninth segment, drives the blood forward to unroll the proboscis. This
niuscular arrangement in the anterior region and the muscular walls
of the vessels themselves at the posterior part of the same division of
the body send the current through the relaxed barrier at the ninth
segment into the muscular ventral blood-vessel of the posterior region,
and onward to the tail, where the trunk ends by bifurcating into the
two dorsal vessels. In each segment a lateral branch leaves the ven-
tral trunk at the anterior dissepiment, turns round and _ proceeds
backward to the next dissepiment, and terminates in the branch to the
dorsal vessel. Further, as first observed by Dr. Fritz Miiller, a sac-
like dilatation takes place shortly after the commencement of the
latter, and it fills at intervals, the distention being followed by a
contraction which sends the blood onward by the branch to the dorsal
vessel. In vigorous specimens, the currents of the blood are as swift
and beautiful as in the tails of young salmon and other translucent
vertebrates. When examined in the liquor sanguinis of the living
animal a distinct nucleus can be seen in the blood-corpuscle.

Professor Leidy on Rhizopods.—Professor Leidy, whose observa-
tions on those animals we have from time to time recorded in these
pages, has lately read a paper containing further results, before the
Philadelphia Academy. This paper is abstracted in ‘Silliman’s
Journal’ for March. It seems that Professor Leidy stated that last
July, in the sphagnum swamps of Tobyhanna, Pocono Mt., Monroe
Co., Pa., he noticed an abundance of a Rhizopod which he thought he
had not previously seen, and which he at first supposed to be an un-
described species, but which he now viewed as a variety of Hyalo-
sphenia ligata. From this, as previously described, it differs in the
test being of a pale sienna colour, and perhaps of greater thickness,
but otherwise is like it. The test is compressed pyriform, with the
length and breadth nearly or about equal, and the thickness one-half.
The lateral borders are obtusely rounded. The mouth is transversely
oval. The sarcode is colourless, and attached to the inside of the
test by diverging threads. The pseudopods are usually from two to
three. Measurements, ‘08 mm. long and broad, and ‘036 thick, with

260 PROGRESS OF MICROSCOPIOAL SCIENCE.

the mouth ‘02 broad and ‘008. Others varied from ‘06 long and ‘08
broad, to 092 long by :064 broad.

In observing the Pocono variety of Hyalosphenia ligata, and the
beautiful and well-marked species Hyalosphenia papilio, he detected
an important point of structure which previously had escaped his
notice. In the active condition of these, and other Difflugians, they
are seen with one or more pseudopods extended from the mouth of
the test, to the margin of which the sarcode is attached, as well as
by diverging threads to various points of the interior of the test.
The interval between the body of the sarcode and the interior of the
test is occupied with water. The extent of the interval increases with
the increase in number and extent of protrusion of the pseudopods,
and also varies according to the degree of emptiness or repletion with
food of the sarcode body. When the pseudopods are withdrawn into
the mouth of the test, the mass of the sarcode expands in a corre-
sponding ratio, and the threads of attachment to the inside of the
test contract in length. The intervening water appears to be dis-
placed through small apertures of the lateral borders and fundus of
the test, which exist in numbers usually from two to half a dozen
or more.

While speaking of Rhizopods, he would ask the attention of the
Academy to some remarks on recent observations on the habits of
several species of Amceba.

One of the species of Amceba which he had most commonly seen,
he took to be the Ameba verrucosa of Ehrenberg, with which the
A. natans of Perty, and the A. terricola of Greef, appeared to him to
be synonymous. ‘This species he had found in many places: in the
crevices of the brick pavement in the yard attached to his residence,
in brick ponds, in the ooze of the rocky shores of the Schuylkill
River, in sphagnum swamps, in marsh mud, &e. It is remarkable
for its sluggish character ; and in appearance reminds one of a little
pile of epithelial scales, or fragment of dandruff from the head.
Appearing quadrately oval or rounded, transparent, and more or less
wrinkled, or marked with delicate wavy lines; the pseudopods rise
in short obtuse mammillary eminences or wave-like ridges, the sum-
mits of which are composed of transparent ectosare, while the central
portion of the body is occupied by a thin, pale, diffused, and finely
granular entosare. This contains one or more vesicles, usually one,
which very slowly enlarges, and then less slowly collapses. In
addition, as part of the structure, an oval granular nucleus is some-
times visible. The food contents generally appear not to be abundant,
and often the creature appears to be empty of food altogether. The
character of its food is the same as with other species of Amceba.
It not unfrequently feeds on Difflugians. In a specimen from
sphagnum water, from Vineland, N.J., last August, he observed an
individual, about the 1, of a millimeter, containing a Difflugia and a
Trinema together. As observed by him, the species ranges from 51; to
1 of a millimeter in diameter.

On the morning of August 27, from some mud adhering to the roots
of Sparganium, obtained the day previously in a nearly dried-up

PROGRESS OF MICROSCOPICAL SCIENCE. 261

marsh, at Bristol, Pa., he obtained a drop of material for examination
with the microscope. After a few moments he observed an Ameba
verrucosa, nearly motionless, empty of food, with a large central con-
tractile vesicle, and measuring ;!; of a millimeter in diameter. Within
a short distance of it, and moving directly towards it, was another
and more active Amceba, the species of which he was not positive.
It was perhaps the one described by Dujardin as A. limax, by which
name, for the present purpose, it may be called. As first noticed, this
Amoeba was limaciform, } of a millimeter long, with a number of
conical pseudopods projecting from the front broader end, which was
zg of a mm. wide. The creature contained a number of spherical
food vacuoles with sienna-coloured contents, a large diatom filled
with endochrome, besides several clear vacuoles, a posterior con-
tractile vesicle, and the usual granular entosarc. The A. limax
approached and came into contact with the motionless A. verrucosa.
Moving to the right, it left a long finger-like pseudopod curved
around its lower half, and then extended a similar one around the
upper half until it met the first pseudopod. After a few moments
the ends of the two pseudopods actually became connate (the second
time he had observed this phenomenon), and the A. verrucosa was
enclosed in the embrace of the A. limax. The latter assumed a per-
fectly circular outline, and after awhile a uniformly smooth surface ;
but the central contractile vesicle remained in the same condition, nor
did he once observe it enlarge or collapse. The A. limax now moved
away with its new capture, and after a short time what had been the
head end contracted, became wrinkled and villous in appearance,
while from what had been the tail end a number (ten) of conical
pseudopods projected. The A. verrucosa assumed an oval form, and
the contractile vesicle became indistinct, without collapsing. Moving
on, the A. limax became more slug-like in shape, measuring about 4
mm. long, by = mm. broad. The A. verrucosa now appeared enclosed
in a large oval clear vacuole, was constricted so as to be gourd-
shaped, and had lost all traces of its contractile vesicle. Subsequently,
the A. verrucosa was doubled upon itself; and at this period the
A. limax discharged from one side of the tail end, the siliceous case of
the diatom, which now contained only a shrivelled cord of endochrome.
Later the A. verrucosa was broken up into five spherical granular
balls, and these gradually became obscured and apparently diffused
among the granular contents of the entosare of the A. limaz. At
one moment the five granular balls derived from the A.° verrucosa
appeared to be contained in three vacuoles, and the A. limax had
amore contracted and radiate form, and then measured 5 mm. in
diameter.

The observation, from the time of the seizure of the A. verrucosa
to its digestion, or disappearance among the granular matter of the
entosare of the A. limax, occupied seven hours.

From naked Amcebe, the test-protected Rhizopods were no doubt
evolved, and it is a curious sight to observe them swallowed, home
and all, to be digested out of their home, just as the contents of dia-
toms are digested. It was also interesting to observe the cannibal

262 PROGRESS OF MICROSCOPICAL SCIENCE.

Amceba swallowing another, and appropriating its structure to its
own, just as we might do a piece of flesh, completely, without there
being any excrementitious matter to be voided.

The Pollen of the Conifere.—The ‘Journal of Botany’ (Feb-
ruary) states that in the recently published ‘Atti del Congresso
Internazionale Botanico tenuto in Firenze, there is an interesting
paper by M. Tchistiakoff on Coniferous pollen, illustrated by two
plates. Whether the grains be deprived of or provided with an air-
chamber, in both cases the extine is composed of two layers, which
are formed simultaneously, by transformation of the two-layered pri-
mordial utricle, where the air-chamber is absent; while in the other
condition the layers appear successively, the primordial utricle being
here very thin, and the inner portion of the extine being laid down
from a peripheral layer of plasma which appears after the formation
of the thin outer portion. At each point where an air-chamber is
destined to appear is seen an interspace between the two layers of the
extine, filled with a small quantity of a gelatinous hygroscopic sub-
stance. By expansion of the elastic outer extine-layer the interspaces
are converted into vesicles; these are seen to be filled with a watery
fluid which soon disappears, and the air-chamber is complete. Mean-
while the several-layered intine has been formed by a secretion of
cellulose. ‘he internal changes are precluded by the dissolution
of the starch, the contents of the grain becoming transformed into
the fovilla; at this time the outer and inner layers of the intine
appear more pronounced, and the intermediate ones more or less
hygroscopic. The periphery of the fovilla then becomes organized as
a new primordial utricle, composed sometimes of a dense, shining,
prismatic, pavement-like plasma (of a number of crystalloids, in fact),
which is very well seen in Sequoia, Cryptomeria, and Cunninghamia ;
but in other cases the prismatic structure is less pronounced, or
is found only locally on the circumference of the uncrystallized
plasma.

MicroscoricAL ConTENTS oF FOREIGN JOURNALS.

The Journal de l Anatomie, publié par MM. Robin et Pouchet.
No. 2, 1877. Paris: Germer Baillicre.—The first paper in this
number of the Journal is one of considerable length, on a subject known
to most of us. It is on the Demodex folliculorum, and is by M. Megnin.
It deals -very exhaustively with the subject, going into the minute
anatomy of the different forms of Demodex, of which four distinct
woodeuts are given. The plate which accompanies the paper gives
the entire structure, the magnification used varying from 300 to 1200.
diameters. In one case a hair-follicle of a dog is represented which
displays the hair, and almost within the hair-sac are to be seen more
than twenty Demodices. The author traces the complete development
of the animal through three of its larval stages, from the condition in
which it is footless to its regular eight-footed stage. He also describes
the different species of Demodex, and deals at some length with their
habits. The article is specially remarkable for the attack which it

NOTES AND MEMORANDA. 263

makes on Mr. Erasmus Wilson, who wrote a paper on the subject of
this arachnid, which is published in the ‘ Philosophical Transactions of
the Royal Society ’ for 1842. It is pointed out that Mr. Wilson has
fallen into the most terrible errors in his description of the animal.
—A paper by M. Poincarré is also of interest to the histologist.
It is upon the “ History of the Thyroid Body.” The author states
that he has examined more than seventy glands, and these have been
in all vertebrate animals, and he states that there is a general resem-
blance of all to each other. But he remarks that while the presence
of closed vesicular spaces is undoubtedly a characteristic feature in
most thyroids, yet that man’s thyroid body is to some extent an excep-
tion. He found that in human glands cysts were extremely common.
Out of 106 specimens examined, no less than forty-three bore cysts
within them.—Another paper, which is of some interest to the micro-
scopic anatomist, is that upon “ The Origin of the Cranial Nerves,”
by M. Duval. This is the conclusion of a series. The magnifying
power employed is, of course, extremely low.

Archiv fiir Mikroskopische Anatomie, herausgegeben von La Valette
St. George und W. Waldeyer. 13 Band, 4 Heft. Bonn, 1877.—
This number contains some very valuable and exquisitely illustrated
papers. First in order is a long disquisition on the general structure
of glands, by Dr. M. Nussbaum. This paper is illustrated by a plate
containing many magnified representations of sub-maxillary and other
salivary glands, of the glands of the pyloric end of the stomach, of
the cesophageal glands, &c., &e. The most interesting paper in the
entire number is that of Herr F. E. Schultze, on Spongicola fistularis.
This is illustrated by three plates, in which we see the difficulty
that the author must have had in referring the animal either to the
Spongiade or to the Hydrozoa. It is exceedingly like the animals of
both classes, and is really a connecting link of an extraordinary kind.
We shall notice the rest of the contents in our next number.

NOTES AND MEMORANDA.

Angle of Aperture, Increase or Diminution of.—On this point
there appears to be a considerable divergence of opinion at the present
moment. We therefore publish a portion of a letter which has been
addressed by Mr. Carl Reddots to the editor of the ‘ American
_ Journal of Microscopy.’ He says :—* I find the following in the report
of proceedings of the Dunkirk Microscopical Society, in this Journal
for January 1877:

«“¢ Professor Smith took a position radically opposed to many
of the received ideas, and in favour of lenses of the widest angle of
aperture for all kinds of work, even going so far as to express his
* opinion that most of the work in histology and pathology done with
the so-called ‘ working lenses’ of narrow angle, would require further

264 CORRESPONDENCE.

attention, and with wide-angled objectives, which recent advances of
the optician had put at our command,’

“This question about the comparative utility of lenses of wide or
narrow angle is one of the greatest importance to all engaged in, or
intending to engage in, any of the branches of the study of pathology,
histology, or biology; to all who own lenses, or who are intending
to own more... . Now, as is said in the report, there is a wide
divergence of opinion among microscopists on this subject. While
a few support Professor Smith, the great majority advocate and
recommend the use only of small-angle lenses. . . . Dr. W. B.
Carpenter has the credit of being one of the most influential advocates
of the small angles. The writer of this is in possession of informa-
tion that, within a few months, an objective of the highest possible
air-angle was shown to Dr. Carpenter at his own house, and he
asserted that he saw a certain histological subject better than ever
before. Rev. Mr. Dallinger, of Liverpool, and his associate, Dr.
Drysdale, have been for some years making the most important con-
tribution to biology ever made. The writer has seen a letter from
Mr. Dallinger that the flagella of a certain monad had been invisible
to all objectives save two, both of the highest attainable angular air-
aperture. Here we have one case of more and one of better. Will
our American histologists contribute their facts ? ”

Death of Professor Pancerii—We have to announce the death of
this distinguished anatomist, which occurred quite recently. He was
suddenly attacked whilst in the act of addressing his class at the
University of Naples, and died in a few moments. It is supposed that
the cause was disease of the heart.

CORRESPONDENCE.

Ture MicroscoricAL EXAMINATION OF Bioop STAINs.

To the Editor of the ‘ Monthly Microscopical Journal.’

No. 1835, CurstNutT STREET, PHILADELPHIA, PENN.,
March 14, 1877.

Dear Sir,—I fear you and your readers are almost as tired of the
blood question as you are of the angle of aperture controversy ; yet I
hope you will, in simple justice, allow me to make one remark, in
reply to your severe editorial comment, in your February number,
upon my views.

Permit me to say, that you have been entirely misinformed
respecting the claim I advance, which is not that we can distinguish
human blood from that of the guinea-pig or dog, as photographed by
Dr. Woodward, but only that in regard to stains containing cor-
puscles within the range of human blood-dises (3359 to g¢op), and

PROCEEDINGS OF SOCIETIES. 265

falsely alleged by a criminal to be those of some domestic animal
slaughtered for food, we can aid the cause of justice, by testifying
positively that the blood never came from an ox, pig, or sheep, the
corpuscles of which, unfortunately for rogues, measure less than
avo Of an inch in average diameter. In this respect I am so far
from being “unquestionably wrong,” that I will undertake to prove
my position, to the satisfaction of any honest inquirer of good stand-
ing, who desires to test the question, by sending me unmarked fair
specimens of blood-stains, under the conditions mentioned above.*

Very respectfully yours, &ce.,
Jos. G. RicHARDSON,

PROCEEDINGS OF SOCIETIES.

Royat Mrioroscopican Society.

Kina’s CoL.ece, April 4, 1877.

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, and the thanks of the
meeting were voted to the donors. The attention of the Fellows was
particularly called to a donation of 150 slides of various objects,
included in the list, presented by the Rev. R. H. Nisbett Browne, and
a special vote of thanks to that gentleman was unanimously passed.

The President announced that arrangements had been made to
hold a scientific evening meeting on the 18th inst.; also that leave
had been obtained to use the lecture theatre for the first Quekett
lecture by Sir John Lubbock on May 2. That being an ordinary
meeting day, there would be a little formal business to transact at the
commencement of the proceedings, and when this had been done, the
remainder of the evening would be occupied by Sir John Lubbock.
At the end of the meeting the Quekett medal would be presented to
the lecturer. Tickets of admission would be issued in due course,
when every Fellow would receive one personal ticket, not transferable,
and one transferable ticket for the admission of a friend. He had also
been requested to intimate that a new list of Fellows of the Society
was in course of preparation, and to ask that any alterations or cor-
rections might be at once forwarded to the Assistant-Secretary,
Mr. W. W. Reeves.

Mr. Thomas Palmer read a paper “On the Variability of the

* We do not doubt the accuracy of Dr. Richardson’s remarks in his new and
qualified position. But so long as it is impossible to distinguish human blood
from that of the dog, we think that the medical jurist cannot place much reliance
on the microscope in his investigations. Still we think Dr, Richardson must be
complimented upon the importance of bis researches.

266 PROCEEDINGS OF SOCIETIES.

Chlorophyll Bands in the Spectrum.” The subject was illustrated by
drawings, and the paper will be found printed at p. 225,

The President, in proposing a vote of thanks to Mr. Palmer, said
he was very glad to find that others beside himself had taken up the
question of the spectra of the colouring matters of plants. The
subject was one which he had worked at for some years, and it had
proved so extensive that he felt he was only just beginning the in-
quiry. These colouring matters are much more complex than is
generally supposed, most of them are undoubtedly mixtures of two or
three kinds of matters, and even the chlorophyll—the green colouring
matter alone, is composed generally of two green matters, which exist
separately in certain plants, and yet these facts had been overlooked
by all observers excepting Professor Stokes and himself, and certainly
they had been entirely ignored by all the Continental observers. The
line it would be most important to carry out would be what were the
chemical differences which gave rise to these changes in the spectra ?
This was a line of inquiry which would necessarily take a very long
time, and would involve an immense amount of work on the part of
an observer. There was a great deal yet remaining to be done, and
he was extremely pleased to find that the subject was being now
taken up.

The thanks of the meeting were unanimously voted to Mr. Palmer
for his paper.

Mr. Palmer said he had noticed a curious effect some time ago
when examining a red solution of litmus; he found that when very
bright light was obtained by using an angular prism as the reflector,
instead of the spectrum going off quite black towards the violet end,
he could see the line H, through the dark band.

Mr. Hawkins Johnson inquired whether the absorption bands
shown by a fluid under the spectroscope indicated any more than the
difference in the colours of fluids, and whether the instrument was
capable of distinguishing between colourless solutions, for example,
between chloride of potassium and carbonate of soda ?

The President said that though there might be in some cases dif-
ferences observed between solutions which appeared to have scarcely
any colour, the spectroscope was not competent to distinguish the
difference in the chemical qualities of two such solutions as those
named. He had, however, little doubt that there were many sub-
stances which appear colourless, which would give definite spectra
if our eyes enabled us to see farther into the red or the blue ends of
the spectrum than they are able to do.

The President said they had a paper that evening by the Abbé
Rénard, which was of much interest in a geological point of view.
The Abbé was present, but although he spoke English well, he felt he
would rather not read the paper himself, though he was quite willing
to address them in French. That course, however, being unusual, at
his request Mr. Ingpen had kindly undertaken to read a résumé of the
paper, the whole of which would be printed in the Journal.

Mr. Ingpen then read a résumé of a paper by M. ’ Abbé Rénard,
of Louvain, “ On the Mineralogical Constitution and Microscopical
Characters of the Whetstones of Belgium.”

land

PROCEEDINGS OF SOCIETIES. 26/

A vote of thanks to the Abbé Rénard for his communication was
carried by acclamation.

The President said that the subject of the mineralogical consti-
tution of these rocks was most important, and they were of much
interest to English geologists, seeing that there were none at all like
them to be found in this country. The occurrence of garnets in them,
however, need not surprise, because they were frequently found in the
slate rocks of our own lake districts, though perhaps not quite in so
great a quantity. He thought that the slates of this character must
be looked upon as thoroughly metamorphic, although they were not
generally considered so; and therefore he regarded it as highly
desirable to work out the subject in order to make out if possible
what changes had taken place in the substances composing them.
He might mention that the Abbé Rénard was the author of some
of the very beautiful illustrations of the microscopical structure of rocks
which were exhibited at the Loan Collection at South Kensington.

A paper by Mr. H. J. Slack (who was unfortunately prevented by
indisposition from being present at the meeting), “On Krupp’s Silica
Cotton,” was taken as read, the President giving a summary of the
general results, and explaining that it referred to the minute fibrous
particles produced when a powerful blast was directed upon a quantity
of melted glassy furnace-slag. Many of the little particles so pro-
duced were like small shots, with one or more fine thread-like tails
attached to them, and when the process was carried on in the open air,
the whole place became filled with these minute particles, which were,
from their hardness and sharpness, extremely detrimental to the lungs
of persons who inhaled them. Mr. Slack’s paper had reference to the
various shapes of the little spheres, and to the remarkable regularity
which existed amongst them, as well as their curious markings. The
President said that these spheres are of great interest in connection
with the structure of meteorites, and might explain the formation of a
number of round glassy particles which he had often found in those
bodies. Nearly all the peculiarities of the artificial product may be
referred to the tendency of a liquid to collect into spheres and of a
viscuous glass to be drawn out into fibres. Mr. Slack’s paper was
accompanied by some illustrative drawings; and a slide, in further
illustration of the subject, was exhibited in the room.

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

The President said that they had received another paper to be read
that evening ; 1t was from Mr. Clifton Ward, “ On the Lower Silurian
Lavas of Eycott Hill, Cumberland.” The paper was rather too long
to read in extenso at that late hour of the evening, but Mr. Stewart
would read the introduction and the general conclusions. The whole
paper would be printed in the Journal (at p. 239).

Mr. Charles Stewart then read so much of the paper as explained
the leading results.

The President proposed a vote of thanks to Mr. Clifton Ward for
his paper. The subject was one of considerable importance, because
at one time it was thought that there was a great deal of difference
between the composition of the ancient and modern lavas. This was

268 PROCEEDINGS OF SOCIETIES.

due, in part, to the fact that these old lavas had undergone a great
change since their first formation; in fact they were really meta-
morphic in a very legitimate sense ‘of the term. Mr. Ward’s paper
showed that originally they were in composition very much the same
as some modern lavas. Mr. Ward had worked out the subject in a
most admirable manner, and the results of his investigations would
be found to be set out in his paper in a very complete and satisfactory
way. He thought the Fellows might congratulate themselves in having
such a subject, so ably treated, in the course of their transactions.

A vote of thanks to Mr. Ward was then unanimously carried, and
the meeting was adjourned to May 2.

Donations to the Library and Cabinet since March 7, 1877:

From

Nature. “Weekly eis. °F 7 63° ce! eer 2 ea
Athenzsums > Weekly :)i..)) sot) 2220 Os.> (aS. en cee Ditto.
Society,of Arts Journal <;- 2; <a) <5 | we (as | so OCI
American Journal of Microscopy ae PP eeerr mess nn lai
The Directory of American Naturalists. By Saml. E. Cassino.

NS Tiieera ‘ . Ff. Habirshaw, Esq.
Transactions of the Natural History Society ‘of Northumberland

and Durham. Vol. V. Part 3 a . « Society.
Journals of the Linnean Society .._. > ) as lpetoy SeeeeOptips
Archivos do Museu Nacional do Rio de ‘Janeiro... .. Le Directeur-Général,
Reports of the Juries, Exhibition 1851 Be .. Frank Crisp, Esq.
Micro-Chemistry of "Poisons. By Theo. G. Wormley, M.D.

New York, 1867 a ; Ditto.
One hundred and fifty slides (various) ... we) deo oe oe tops DRO eels eiemNesp ele

Browne, M.A,

Dayid Bogue, Esq., was elected a Fellow of the Society.

Watter W. REEvEs,
Assist.-Secretary.

Scientific Evening of the Royal Microscopical Society.

A scientific evening was held at King’s College on Wednesday,
April 18, of which a detailed account, too late for the present number,
will be given in the next one. We may mention that the upper set
of rooms of this Institution were thrown open, and were filled by
members who exhibited a vast variety of objects—many of them living
—and apparatus of novelty. Tea and coffee were served in an ad-
joining apartment, and altogether the meeting was a most pleasant
and successful one.

THE

MONTHLY MICROSCOPICAL JOURNAL,

JUNE 1, 1877.

I.—On the Mineralogical Composition and the Microscopical
Structure of the Belgian Whetstones.

By Rev. A. Rénarp, 8.J., F.R.MLS.
(Read before the Royau Microscopicau Soctety, April 4, 1877.)

Amone the rocks used as fine whetstones, there are none, I think,
more justly celebrated in Europe than those found in the neigh-
bourhood of Viel-Salm, in the province of Liege, Belgium. They
are in shape parallelopipeds, composed of a stratum more or less
deeply coloured yellow, and of a stratum coloured blue-violet ; and
are exported to every country in Europe and the Orient.

Although I intend to direct attention chiefly to their constitu-
tion as found from their study under the microscope, and to the
light which this method of study throws upon the origin of those
rocks and upon their physico-chemical constitution, yet I shall
briefly notice some of the interesting geological considerations
relative to their bearing and to their relations with the adjacent
strata.

The hones of the neighbourhood of Viel-Salm are found among
the rocks which Dumont called Salmien, but which seem to resemble
very much the English Cambrian, and to be the equivalent of the
schist of Tremadoc.

They form veins in the Cambrian slate of from one to two
centimeters thick, but whose direction is so irregular, and whose
composing strata are so winding and tortuous, that many geologists
have mistaken them, and they have been not seldom described as
real veins; whilst I have shown, supported, moreover, by Baur and
Dumont, that they are regularly intercalated in the stratification,
and form real strata in the slate, with which it is intimately united.

The facts upon which I base my deductions and the macro-
scopical descriptions, are given at length in a memoir which I
devoted to this question.

Before touching upon the microscopical study, let me say a
word or two on the relations between the whetstone and slate, as
by that means I may be more readily understood in the description
of the whetstone as it appears under the microscope.

When one sees a hone haying one layer of a yellowish white

VOL. XVII. %

270 Transactions of the Royal Microscopical Society.

material, and another of bluish slate distinctly separated by a
straight line, sometimes of perfect regularity, there is a tendency
to suppose that they are two fragments of different rocks fastened
together one above the other, the juxtaposition being due rather to
art than to nature; but when these stones are seen in the place
which they occupy in the strata, one readily observes that the vein
of whetstone is intimately united to the slate, and that the work-
man has nothing else to do than to square the fragments. In
certain exceptional cases, however, art is made to imitate nature ;
and the workman sometimes, by fastening together fragments of
different colours, gives to the market a hone that differs not in
appearance from those formed by nature.

Although this line of demarcation is usually found very distinct
between the two layers and marking the direction of stratification,
it also happens frequently that the whetstone passes imperceptibly
into the slate, in such a way that at a certain point it is no longer
possible to distinguish whether slate or whetstone is in question.
It might be said there was a sort of mutual penetration of the two
layers.

: There is one character, common to the veins and the incasing
layers, to which special attention should be given. It is this: the
foliation, oblique to the stratification, is prolonged from the slate
into the whetstone. Sometimes this foliation is but faintly charac-
terized in the compact varieties, but it is always present in a latent
state, and if the slate be broken, the lamina comes off, passing across
the whetstone, and the fissure is prolonged with a regularity and
constancy of angle which shows evidently that the two rocks have
a common cleavage. I have proved that there is also present in
these two rocks a second cleavage, not so easy, but, like the first,
clearly distinct from the stratification. The existence of this
cleavage shows, first, that the layers of whetstone existed before
the uplifting of the strata; and the coexistence of the two
cleavages obliges us to admit that the rocks of this group have
been subjected on two different occasions to a pressure, brought to
bear in two different directions, as contended in similar cases by
Mr. Sorby. The easier cleavage must have been produced while
the rocks were still in the plastic state, the second when they were
already more solidified. I have dwelt upon the characters common
to the two rocks, because they are in close relationship with the
details of microscopical analysis which follow. To sum up, the
whetstones are contemporary layers with the incasing slates, and
have been subjected to the same mechanical actions as all of the
phylladic rocks of this group.

After this exposition, belonging rather to geology, let us inquire
what are the minerals that constitute the whetstone of the neigh-
bourhood of Salm. It should be remarked that this question cannot

a

On the Belgian Whetstones. By Rev. A. Rénard. 271

be answered by macroscopical examination alone, since the compact-
ness of the rock and the fineness of its grain is such that, even with
the aid of the magnifying glass, it is impossible to individualize the
mineral species which make up the whetstone. It appears in
general as a homogeneous substance of clear colour, and the geolo-
gists who have occupied themselves with this rock have limited
themselves to giving the description of some of its physical pro-
perties and the details relative to its bearing, touching only inci-
dentally on its composition. This, however, is not surprising when
it is remembered that these skilful observers had not at their
disposal microscopical analysis, which I have been able to use.

Still, on examining with attention the lamine or the fractures,
peculiarities may be seen at their surface which give a glimpse of
the elements that microscopical analysis makes known. With the
naked eye phylladic plates, closely aggregated, may be perceived.
This phyllite has not the silvery or pearly aspect of sericite ;
neither has its pyrognostic characters. It is these lamella which
make up the fundamental mass of the rock. By the reflexion of a
strong light there may be seen on these phylladic membranes
a glistening due to crystalline granules of infinitesimal dimensions.
These shining grains would naturally be attributed to quartz, were
it not that study at the microscope discovers in them optical properties
and crystalline forms which put aside this supposition. The micro-
scopical dimensions of the elements mingled with the phyllite never
determine the structure which we have called by the name of
gneissic in our study of the rocks of the French Ardennes; at
least, it does not appear to the naked eye nor under the magni-
fying glass. Among the accidental elements visible to the naked
eye should be counted iron glance, hydroxid of manganese, which
often impregnates whetstone, quartz, and pyrophyllite.

Let us pass now to the study of the ultimate constitution
of the whetstone, as shown by microscopical analysis. In order
to come at the results given in this paper, I have cut and polished
more than seventy thin sections of this rock. ‘To have a general
idea of the ultimate structure of the whetstone, we should study
it first with the help of weak magnifying powers. There is
then perceived a colourless micaceous substance which seems to
make up in great measure the fundamental mass. These phylladie
fibres, generally elongated and colourless, appear peppered with a
black dotting, owing to a numberless quantity of granules which
have the appearance of opaque points. There are seen also in-
numerable microliths, some like simple dashes, and others of larger
dimensions, but much more rare, showing a light bluish tint.
Finally, with the help of a polarizing apparatus, it may be seen
that one part of the mass belongs to an isotropic substance.

Commonly the phyllite is completely covered by the prodigious

x 2

272 Transactions of the Royal Microscopical Society.

number of particles, more or less circular, scattered along the surface
of the filaments. The elongated microliths are in line, and grouped
with their greater axis parallel to the direction of the micaceous
lamine. Clearer regions are also remarked in this mass, almost
without interpositions, the arrangement of which contrasts with the
general disposition of the elements. These veins, having a thickness
of less than a millimeter, advance irregularly across the rock. They
are made up chiefly of micaceous substance, and do not seem to be
fissures filled up later on, but rather to have been formed at the
same time that the rock took its distinctive petrographic character.
They are found to contain, though in small proportions, all the
elements which we discover as constituent parts of the whetstone.
A fissure, filled later on, would not be filled with all the substances
identical with those which form the rock. This kind of micro-
scopical primary veins does not cross the whole of the thin section.
They often form lenticular regions in it, of the same structure and
composition as the little veins of which we have just spoken.

None of the microscopical characters by themselves allow of a cer-
tain identification of the lamelle with a determined phyllite. I give
up, however, the opinion of Dumont, who considered, without sufli-
cient proof, pyrophyllite to be the constituent principle of the phyllas
of the Ardennes ; and I would bring these phyllitous fibres into con-
nection with Damourite, a mineral which the chemical analyses
of Messrs. Davreux and de Koninck, jun., have shown to exist
in a garnet-bearing rock of Salm, that presents, as will be seen,
many analogies with the whetstone. Still it is very difficult to
decide this point with certainty, since it is impossible to isolate
the lamellae for a separate analysis, and they are dotted with foreign
minerals. On the other hand, the optical reactions are unsatis-
factory ; for, as is known, one of the problems the most difficult of
solution in the microscopical analysis of rocks is the specific deter-
mination of the different micas, especially when they are found
without distinguishable crystalline forms, and with extremely small
filaments, as is here the case.

Let us now pass to a more minute study of the different elements
contained in that rock. For this we must use a magnifying power
of from 400 to 600 diameters. With such aid we may perceive
the innumerable granules, scattered over the surface of the lamine,
become clearly and distinctly individualized, and the rock, at certain
points, appears to be composed of globular forms whose agglomera-
tion almost completely veils the micaceous element. The mean
dimensions of these circular forms rarely exceed 0°02 mm. ; and,
according to an approximative calculation, some parts are so beset
with them, that a millimeter cube of rock contains over 100,000.
These globules, for the most part rounded, sometimes also elongated,
are, in some cases, terminated by crystallographic forms. They

Se —

On the Belgian Whetstones. By Rev. A. Rénard. 273

may be perceived to be bounded by regular lines, and one may dis-
cover their lozenge-shaped faces, which are to be referred to the
rhombo= dodecahedron. The dimensions of these crystals are ordi-
narily so minute that they are not attacked in the polishing
process, and thus they are preserved to us in the integrity of their
form. They are therefore, in general, complete on all sides. It
is difficult to judge of their optical properties, as they are set in
a double refractive substance ; but by observing those of larger
size that protrude on both sides of the micaceous lamin, or those
isolated at the extremities of the thin sections where the thickness
is least, they may be seen to be dark between the Nicols’ crossed
risms.

i Their perfect isotropism and their crystalline form place them
amongst the minerals of the first crystallographic system. Seen by
transmitted light they appear completely devoid of colour, bordered
by zones of deep black, which diminish in intensity toward the
centre of the crystal, where the colourless part sparkles with ex-
ceeding briliancy. I have found these crystals in great numbers
in all the various kinds of whetstones of the Salm formation. At
one time they are gathered together at one point, at another they
form lines or chaplets, and again they are isolated.

With this ensemble of characteristics one may ask to what
mineral species we are to refer these globular-formed crystals.
However strange the conclusion may appear, I refer them to the
garnet. In support of this I may show that the interpretation
making it a garnetiferous rock is in no way opposed to any of the
details of the micrographic description I have given, that it explains
naturally all the facts that I have mentioned as well as the physical
properties of the whetstone of Salm.

The rhombo = dodecahedral forms, or globular crystals, which,
however, now and then present a rhombic face, point out a mineral
of the first system. The single refraction on which I before
insisted now comes to support my interpretation. The high index
of refraction of the garnet (4 = 1°772) shows itself by the unusual
brilliancy displayed by the crystals when observed by trans-
parency. *

The high specific gravity of the rock (= 3°223) is also
explained by the density of the garnet, which forms a great part of
it. The specific gravity of garnet, as is known, reaches to 3°4 and
even 4°3. Hitherto it has been frequently asked what the sub-
stance could be that enabled these whetstones to wear even steel,
and it was the supposition up to the present time that the element

* To explain this fact, it is to be remembered that luminous rays penetrating
a refracting body by a point, and forming at the point of incidence a hemispheric
pencil, form in refraction a cone whose angle at summit is given by the equation

sin. 7 =—- This angle diminishes in proportion as n increases.
n

274 Transactions of the Royal Microscopical Society.

was no other than quartz finely divided and dispersed through
the stone. My researches prove, however, that they contain
scarcely any quartz. Hence it is to the garnets that we are to
attribute this hardness of the rock, for we know that the specific
hardness of garnets is comprised between 6°5 and 7°5 of the scale
of Mohs. The discovery of garnets in the slates of Recht by my
friend Dr. Zirkel, Professor at the University of Leipsic, is another
support of this interpretation, as the slates of Recht belong to the
same formation as the rocks of Salm, of which they are the con-
tinuation in Germany.

The largest garnets of our preparations show inclusions which
are found so often in this mineral when studied under the micro-
scope; we observe also in the largest those irregular fissures which
are so characteristic of garnet.

But how is the yellow colour of the whetstone explained if we
admit that this rock is, as we have said, almost exclusively com-
posed of garnet? In our endeavours to explain this colouring, we
have succeeded in determining the sort of garnet to which this mineral
belongs. We place it in the variety called Spessartine, and we shall
soon see that another kind of proof confirms us in this classification.

In considering spessartine as the principal element of the
whetstone, we see that the union of a very great number of
infinitely small crystals of this mineral should produce, when
regarded ‘ ensemble,” a yellowish-white tint; for the purest
spessartine is in little transparent crystals of a pale yellow, im the
island of Elba, at St. Marcel, in the diamond sands of Brazil,
and in Maine in the United States. We thus easily understand,
in admitting that spessartine is present here, how an agglo-
meration of small garnets of this variety can produce the yellow
tint of the whetstone. But what indicates still more certainly the
manganese garnet is chemical analysis. M. von-der-Mark has found
as much as 21-71 per cent. of MnO, and M. Pufal has found
17°54 per cent. in a specimen he has had the kindness to analyze
for us. This large quantity of manganese should not cause sur-
prise, since it is known that the spessartine of Haddam, in Connec-
ticut, analyzed by Rammelsberg, gave 33 per cent. of MnO. Let
us also bear in mind that the presence of manganese manifests
itself in a remarkable manner when tested by a bead of borax.
Let us also remark that all the surrounding rocks are as it were
impregnated with manganese; it is found in the form of veins, or
combined in the remarkable metamorphic minerals (ottrelite, de-
walquite, &c.) of that region.

And it is near veins of whetstone that MM. de Koninck and
Davreux discovered the beautiful little garnet crystals of which they
have given the description,* and whose composition approaches

* *Bulletins de PAcadémie Royale de Belgique, 1873.

On the Belgian Whetstones. By Rev. A. Rénard. 275

more nearly that of the typical variety of spessartine than that of
any specimen of which an analysis has been published up to the
present. I may add, that some specimens of whetstone have lost
their colour through an impregnation of hydroxid of manganese.
These became completely black, but in thin sections there imme-
diately appeared all the essential elements of the rock, coloured,
however, a faint brown by the foreign matter.

A third element of the whetstone of Salm is schorl. This
mineral is far less widely spread than the two which I have just
made known. ‘The principal microscopic characters which this
mineral offers in the rock are the following: the form of the
sections is that of a parallelogram whose great axis may have on an
average from 0:07 mm.to 0'08mm. In width it reaches 0°01 mm.
Ordinarily the sections of the mineral are terminated at one extre-
mity by planes intersecting each other at an angle more or less
open; the opposite side being terminated by an almost straight
line. They are traversed by crevices which are sensibly parallel to
the base, and often appear notched. Their tint is not homogeneous ;
it is pale green, blue, greyish, sometimes growing stronger at one
extremity of the section. ‘This mineral is birefringent, and is
strongly dicroscopic. The sections are often filled with black and
opaque little spots. It is known, moreover, that M. Angor has
discovered this mineral in a great number of slates and schists.
We find again in our thin section a most perfect resemblance
between the mineral he considers to be schorl and those which
we have been led to consider as the same. The forms of that
mineral, we have said, show a difference of development for
the two extremities: this difference is the very same as that
which affects schorl; which presents us so frequently with the
most classic examples of enantiomorphism. We have said that
certain sections show two different tints at the two extremities;
this difference of tint is a well-known fact in the case of this
mineral. Indeed, we know that the transparency of the tourmaline
varies in the same crystal with the direction relative to the axis of
the rhombohedron. It is more sensible in a perpendicular, and
feebler in a parallel section, a fact which must be referred to its
dicroscopism. But besides this phenomenon it is not uncommon
to find that the same crystal presents different colours at the two
extremities, or at least a tint of unequal intensity. According to
M. von Lasaulx, the same thing is noticeable in the microscopic
tourmalines enclosed in the garnets of the granulites of Saxony.
We have just said that these crystals of schorl sometimes appeared
as if broken; that they had undergone certain deformations. We
remark, indeed, that these small sections of schorl appear broken,
and that their various fragments lie at a short distance. M. Rosen-
busch observes that those which are seen by the microscope are

276 Transactions of the Royal Microscopical Society.

ordinarily curved, a fact we have remarked ourselves. As we have
said, it is not rare to find the sections of schorl furrowed by fissures
more or less parallel to the base. It was believed by some micro-
scopists that this fissure represented a cleavage. Now, the best
mineralogical works make no mention of a cleavage in this direction.
Dana, Naumanm, and Des Cloizeaux mention cleavages only follow-
ing R, o P2; besides this, these cleavages are not easy. We are
therefore inclined to admit that these ruptures are the effect of
mechanical action, as, for example, the stretching of the beds at the
moment of foliation. The rupture in these little prisms must neces-
sarily be made parallel to the base, where the points of more feeble
resistance are found. I add that M. Zirkel and myself have been
able to prove that these prisms belong to the hexagonal system.
Tn a research that I made with him, we have found that in a
thin section of a schist of the Ardennes a hexagonal section of this
dicroscopic mineral was dark between the crossed Nicols’ prisms.
This fact wholly confirms our interpretation as to the crystalline
system of these little prisms.

In the few pages devoted by M. Zirkel to a microscopic de-
scription of the slates of Recht, he pointed out the presence of a
prismatic mineral of a greenish yellow colour. High powers of
the microscope are needed to observe this mineral, the prisms not
being more than 0°03 mm. in length and 0°005 mm. in thickness,
so that it is difficult to determine all the faces of the crystals, which,
though complete, have not very well defined edges. Irregular
aggregations are often found composed, sometimes of one or two
individuals, sometimes of twins in the form of a knee. As none of
the characteristics of these small crystals are opposed to those of
augite,* M. Zirkel believed that he could class it with that mineral.
Such are, in brief, the micrographic details he gives upon these
microliths.

We find them again in great abundance in the whetstone, and
there under a great variety of very interesting crystalline forms,
which have not as yet been pointed out by any micrographer.
These prisms, which are identical with those remarked by M. Zirkel,
are scattered through the whetstone sporadically, and are dis-
tinguished from the prisms of schorl by their form, by the way
they are grouped, by their tint, and also by their exiguity. At
different times these prisms are ranged in lines, verge towards each
other, and interlace, maintaining the while almost constant angles
in their superposition. In some sections it is remarked that the
prisms follow the undulations of the micaceous substance. We
shall add nothing to the excellent description which M. Zirkel has

* On this subject M. Zirkel remarks that our friend C. A. Lossen, of
Berlin, has found in inferior Devonian, near Winterburg, some crystalline schists
in which the macroscopic augite appears as an essential element.

On the Belgian Whetstones. By Rev. A. Rénard. 277

given of the simple crystals of this kind. We find, however, in our
sections, remarkable examples of grouping and of twins, of which
we shall speak more in detail.

When there is a certain quantity of these microliths gathered
together, one is sure to remark, for some among them, a certain
manner of adhesion or of superposition, which is too regular and
constant in its repetition not to be subject to some crystallographic
law (Fig. a).

Wy

ha

Among these little crystals those of simpler form show the
geniculated twins with an angle of about 60°, and in general it is
with this angle that the crossings or superpositions of the minute
prisms take “place. Oftentimes it isa granule of spessartine that
serves asa point of attachment. The prisms do not preserve the
same thickness through their entire length. In the upper part, for
example, they appear a simple line, and toward the middle they
suddenly bulge or swell out. Finally, im many cases they give
rise, by their ramified disposition, to forms that may be considered
as the skeletons of crystals that I have discovered in the whetstone
of Sart, and of which I am now about to speak.

In the thin sections of this whetstone there are to be observed
triangular compound crystals, yellow, less transparent, and whose
dimensions reach even to 0-05 mm. (Fig. b). These groups may be
reduced to a single fundamental type, namely, a heart-shaped twin
haying an angle of 60° at the summit. These crystals are formed
of minute prisms that adhere to one another very perfectly, of
which I have spoken above. ‘These sections are covered with
parallel striz on both sides of the triangles, producing very dis-

278 Transactions of the Royal Microscopical Society.

tinctly those striae which erystallographers generally call osec/-
latory.

it is not the microliths of Sart, however, that show the most
remarkable crystalline forms. Some specimens of the whetstone of
Ottrez exhibit, with a microscope of 600 or 700 diameters magni-
fying power, a multitude of minute triangular crystals of the
utmost delicacy and perfection (Fig. ¢). It has been shown that these
little geometric solids are to be classed, on account of their angular
measure and their form, with the geometrically disposed microliths
of Sart and with the geniculated twins. But, on the other hand,
inasmuch as the fundamental character seems to point them out as
belonging to those regular aggregations, even in so much do they
differ from them by their perfect transparency. They are not
formed by the gathering together of a number of minute prisms, as
is the case in the specimens from Sart, and are perfectly colourless.
‘They are exceedingly small, the base often not measuring more
than the thousandth of a millimeter. That some idea may be had
of their delicacy, it may suffice to state that it is not rare to find
two or three of them superposed. If the observer turn the micro-
metric screw he can readily convince himself that they occupy
different planes even in the extremely minute thickness of the thin
sections. Thanks to the delicacy and the perfection of their forms,
one may attempt, with some chance of success, to determine the
crystalline type in which the mineral is to be classed. The
minuteness, however, of its dimensions, and the impossibility of
isolating it, impose the necessity of pronouncing with great reserve
‘on the mineralogical nature of these remarkable microscopic twins
to which I now for the first time call attention.

By the inspection of the outline and of the extremely delicate
line that joins the summit with the obtuse angle opposed the ob-
server may readily recognize hemitropical forms; and the two
halves polarizing with complementary colours prove in their turn
that these two parts have their optical axes placed as they should
be in the case of a hemitropy similar to that which we find in the
ereater number of these twins.

This mineral constitutes, in the great majority of cases, twins by
juxtaposition ; however, some are found which are twins by pene-
tration ; those, for example, which cling together by their summits,
recalling what one sees in certain twins of tridymite, mentioned by
Vom Rath. The angles of these rhomboids, to judge them by
approximate valuations, such as can be made by the microscope, are
of 60°, 90°, and 120°. In other terms, these are the angles given
by the hemitropies of the crystals of the rhombic system which
have an edge of about 120°, and for which the hemitropy is made
following the rule = Plane of hemitropy = a face of the prism of
about 120°, that is to say, a dome, 3 P oo for example, the principal
axis of the two individuals forming together an angle of about 60°.

On the Belgian Whetstones. By Rev. A. Rénard. 279

This interpretation explains the heart, or geniculated, twins which
are presented to us in the little prisms contained in almost every
thin section of the whetstone, and of the regular groupings of the
rocks of Sart.

In spite of all the details resulting from a minute study of
these remarkable crystals, we must, however, confess that they are
not sufficient to determine to what species of mineral they belong.
We are here before one of the most difficult problems of petro-
graphy, that of identifying with a macroscopic species, crystals of
such small dimensions as those which we have discovered, and
which besides show characteristics which seem to bring them near
to known minerals. Yet there is nothing to prove that these
microliths are not a new species. The abundance of material
that we have at hand, and the extraordinary development of these
forms in certain specimens that we have endeavoured to analyze
with a scrupulous care, authorize us to think that they ought not to
be referred to augite ; in truth, epidote offers points of resemblance
for the colour and the twin; for we know that Kokscharow has
found hemitropies of epidote resembling these we have here ; but
the other characteristics of epidote are too different to permit us to
ascribe to it these little twinned prisms.

In order to dissipate the doubts raised on this point, I have
examined the analogous forms given us by the mineralogists for
the minerals of the class of silicates, and I have been struck with
the resemblance between the twins of chrysoberyl and our little
twin crystals. What, besides, adds a certain value to this con-
sideration is, that chrysoberyl is found in crystalline schist, as, for
example, at Tarakoja in the Ural Mountains, and Marschen in
Moravia. Stratigraphical and petrographical studies, moreover,
lead us in like manner to consider the whetstone that we are
describing as belonging to the series that we designate as crystal-
line schists.

In terminating this micrographical part of the article relative
to the whetstone, let me remark that the oligiste iron appears
but rarely, and even then sporadically, in this rock, and that it
appears more generally, and especially, in contact with oligistiferous
slate, whose relations with the rock we have just described we will
now briefly study.

At the commencement of this paper I drew attention to the
fact that the whetstone appears almost constantly associated with
the oligistiferous phyllade, in which it forms regularly intercalated
strata. We have seen that these two rocks are perfectly adherent,
as also that the foliation of the one is common to the other; now
it remains to inquire whether their mineralogical composition and
micro-structure cannot throw some light on the relations that exist
between them.

Let us see therefore what data the microscopical analysis gives

280 Transactions of the Royal Microscopical Society.

us for the oligistiferous phyllades. Here we have as guide
M. Zirkel, who examined some thin sections of the phyllade of
Recht, which is definitively the same as that associated with the
Belgian whetstones. My observations on the oligistiferous phyllade
of Ottrez, Bihain, Viel-Salm, &c., agree in every point with those
of M. Zirkel.

. M. Zirkel finds that the red grains scattered throughout this
rock are in fact, as Dumont had admitted, oligiste iron; that under
the microscope they appear of a red colour, and the sections, though
generally irregular, are, however, sometimes hexagonal. M. Zirkel
attributes the red colour of the phyllade to the accumulation of
lamellz of this mineral. These lamella, as well as the other con-
stituents of this rock, are enclosed in a micaceous substance, which
constitutes the fundamental mass of the schist. The third con-
stituent recognized by M. Zirkel is garnet, which appears in his
preparations with the same characteristic marks that we have
already seen in the whetstone. We would remark, however, that
this mineral is far more abundant in this rock than in the slate.
He makes mention besides of prismatic microscopical crystals, some
of which are geniculated twins, and a fifth mmeral composed of
granules generally flattened, black and opaque, irregularly termi-
nated, and which are less than 0°'015 mm. He is inelined to
regard them as carbonaceous particles so often found in black or
blue schist. .

We have but little to add to this excellent description of oligis-
tiferous slate; the only additional element that we have yet recog-
nized in plates of this rock is schorl, whose sections appear here
like the sections of this mineral which we have examined in
describing the whetstone of Salm.

If now we compare the results which M. Zirkel has obtained for
the composition of the oligistiferous slate and those which we have
noted in this communication, we shall remark striking analogies in
these two rocks, which we were far from suspecting, but which per-
fectly explain the phenomena presented by their microscopic study.
In both cases a micaceous substance constitutes the fundamental
mass; there is the same structure, both contain garnet and small
prisms quite identical, and in both schorl is present. The difference
consists only in the fact that the slate contains lamelle of oligiste
iron and carbonaceous granules, while these two minerals are rare
in the whetstone.

There yet remains an important geological question to be dis-
cussed: it has reference to the origin itself of the rocks. Let it
suffice to renrark that I have not met there any elements with
traces of clasticity. On the contrary, everything seems to show
that its essential elements are crystalline, formed cn situ. Resting
on the ensemble of facts which I have observed, stratigraphic as

On the Belgian Whetstones. By Rev. A. Rénard. 281

well as petrographic, I am inclined to admit that the bands or
zones of the whetstone are real layers imbedded in the Cambrian
formation of the province of Liege, and that they were deposited in
the same way as the adjoining slates, in the Cambrian sea, with the
proper characteristics that make them differ, from the very moment
of their deposition, from the sediments that furnish phyllades.
Without denying that a metamorphic action has affected this mass,
in a general way, I am inclined to think that this phenomenon
alone has not been able to effect the concentration of the mineralo-
gical elements that constitute the whetstone.

In conclusion, I add that this rare rock of Salm and the neigh-
bourhood presents a mineralogical composition such as I have never
found in any of the rocks ordinarily designated as razor-stones. I
may be permitted here to thank MM. Richter and Dana for the
information and specimens of whetstones they have forwarded to me.

( 282 )

II.—Observations on the Structure of the Red Blood-corpuseles of
a young Trout. By W. H. Hammonp, Esq.

THe circulation of the blood in a young trout may be so plainly
viewed under the microscope, owing to the great transparency of
the fish, that it occurred to me it would be a very good subject for
experimenting on to ascertain if the red blood-corpuscles contain a
nucleus in their living state as they flow in the vessels. By get-
ting the little fish in a suitable position, as it swam in a cell full of
water, I was able to use an objective giving an amplification of
over 300 diameters; with this power I could see the corpuscles
where they flow, slowly and singly, very distinctly in the smallest
veins. When the red corpuscles presented their broad surfaces,
they had the appearance represented in Fig. 1, a central spot or
nucleus, and a rim round the margin. I also had good side views
of the corpuscles in the small veins, just at the point where they
branch out of the larger ones; here the corpuscles were continu-
ally turning over, and at times one remained stationary for a little
while ; when the edge was exactly opposite to me, they had the
appearance shown in Fig. 2, the central spot or nucleus clearly
projecting on both sides of the blood-disk. I could also see, as the
corpuscles rolled over, that their outer part is a cylindrical ring; a
section of one would have the appearance shown in Fig. 3. These
observations were repeated many times on young trout varying
from a day to three weeks old.

Fiaq. 1. Fig. 2. Fig. 3.

The question is\ important, for Professor Gulliver, F.R.S.,
in his paper entitled “Observations on the Sizes and Shapes
of the Ked Corpuscles of the Blood of Vertebrates,” * says, “In
every animal, without any known exception, of this great divi-
sion (Pyrenemata), the red blood-corpuscle is characterized by
the presence of a nucleus, which is plainly demonstrable in the
majority of the corpuscles when examined on the object-plate under
the microscope. Nor is the taxonomic value of this fact at all

* «Proc. Zool. Soc., June 15, 1875.

S < Poe

Le), a
ALDorsucdir ad nee bet

Heterotrichus inzequarmetus, Donn.

A New Acarite. By M. A. L. Donnadieu, DSc. 283

affected by the old and still vexed question, as to whether the
nucleus exists distinctly or at all in the corpuscle while it circu-
lates within the living blood-vessels, or is formed only after its
exposure to the atmosphere or chemical reagents. Many years
ago De Blainville, Valentin, Henle, and others, and more recently
Savory, supported the latter view; and the former was adopted by
Mayer and Kolliker, to which Brunke has lately conformed. The
subject cannot be entertained here ; only it may be noted that I
have satisfied myself of the substantial accuracy of Mr. Savory’s
observations on the blood-disks of some British Batrachians, but
not of the validity of his conclusions therefrom, and that I have
plainly seen in certain fishes the projections on the corpuscles,
indicative of a nucleus, while they were flowing within the living
blood-vessels.”

The facts, described above, were shown in the living fish at a
late scientific meeting, at Canterbury, of the East Kent Natural
History Society, and were regarded with much interest by the
members present.

IIL—A New Acarite. By M. A. L. Donnaninv, D.Sce., Professor
at the Lyceum of Lyons.

Puate CLXXXIILI.

In the month of April, 1873, in emptying into a plate full of weak
acetic acid * the contents of a collection from a sweeping net, I
found an acarite which appeared to me to be quite new. It is diffi-
cult for me to give any exact idea as to its origm. The glass was
full of acarites of all kinds, Scirus, Trombidium, Gamasus, &e., and
with them a great many insects, among which the Diptera were
most numerous, more especially those allied to the common fly.
With regard to the specimen which I found, which, in spite of

EXPLANATION OF PLATE CLXXXIII.

Fic. 1.—AHeterotrichus inequarmatus. Entire animal seen from behind. The
left half is represented without the numerous hairs which cover the body, in order
to show the tubercles which support these hairs.

Fic. 2.—A tubercle very much enlarged, and showing the two kinds of hairs.
a. Long and pointed hairs divided into segments. 6. Short hairs with the
peculiar spherical swelling.

Fic. 3.—Extremity of one of the feet. a. Tarsus. 6. Edge of the cupuliform
membrane deprived of hooklets. c. Two large internal hooklets. d. Nine small
spatuliform hooklets. jf. The three large external hooklets. g. hairs,

Fic. 4.—Acarite magnified twice.

* See, for an explanation of this process of research, ‘ Recherches sur les
Tétramiques,’ par A. L, Donnadieu, 1875, p. 27.

VOL. XVII. Y

284 A New Acarite. By M. A. L. Donnadieu, D.Se.

all my search for others, was but that of a single individual, I
believe that it is an undeveloped form (hypopiale) of Gamasus,
which might very well have proceeded from one of the Diptera
which I shall refer to. ‘The mouth, too badly defined to have any
significant value, the general form of the body, and, above all, the
absence of reproductive organs, seem to me to confirm this idea.

I would observe that my description refers to the actual form of
the individual, without in the slightest degree indicating what the
ultimate appearances may be. I have called it Heterotrichus
inequarmatus, which name can be applied to the complete form
when I am fortunate enough to obtain it.

The body, which is very transparent, is ovate; the rostrum
makes a very slight bend forwards, through which one distinguishes

only that which should be the palpx. The inferior surface is,

flattened, the upper one is swelled out (bombée). ‘The skin on the
entire region of the body is granular, and presents grooves in
the neighbourhood of the feet and rostrum.

On the dorsal face one sees a series of rounded elevations like
little tubercles. At their level the skin is slightly brownish ; they
serve to support the hairs which by their nature justify the generic
name that I have given the animal.

These hairs are, in fact, of two kinds. The one spiny at their
ends seem formed of a series of joints, which fit one into the
other. They are twice to three times the length of the body.
They are comparatively slender, but are nevertheless rigid enough
to give the animal the appearance of a body covered with sharp
spines. ‘The others are short, and terminate in a slender point;
almost in the middle they present a very large vesicular swelling
filled with a mucous-like fimd, which by its transparence contrasts
vividly with the brownish tint which fills the rest of the hair.

The disposition and number of each of these hair-like processes
on their little elevations of the surface are unimportant; but these
latter are so abundant that the whole body disappears beneath the
mass of hairs which cover it.

The feet, eight in number, are short and decidedly conoid.
They differ very slightly in length, the anterior pair being slightly
shorter than the others. ‘Two pairs are directed in front, and two
Betas At the point of origin they sensibly approach each
other.

Their mode of termination is the most remarkable point about
them. The conical tarsus is terminated by a wide membrane
capable of forming a cupuliform caruncula, on the lower border of
which are placed hooklets. The latter are of two forms, and their
appearance led me to give the specific qualification to the animal of
imequarmatus. The first are freely bent, as is the case in the
majority of the species. They thin away from base to extremity,

The Action of Chlorophyll in the Vine. By Giovanni Briosi. 285

and their curvature forms a more or less marked semicircle. Two
are directed to the front and the external border (le bond externe).
Three others are seen in the outer border, but they are directed
backwards. Between these two series are placed the hooklets of
the second form (les crochets de la deuaieme forme). The latter
are placed regularly upon the inferior borders of the tarsal ex-
tremity, and are nine in number. They are short, and their initial
part assumes up to the point of its insertion a more or less spatular
form. Towards their summit they curve brusquely upwards, and
terminate in a very short conical point. They are all equal in
their length, which does not exceed a third of the preceding ones.

Finally, the feet are covered with hairs analogous to the long
ones on the body, but much shorter and more transparent.

By all the characters that I have pointed out, this acarite
appears to belong to the Gamasidx, to which certainly belong the
adult forms represented in the present state of our knowledge by
the undeveloped stage of certain Gadflies—Journal de l Anatomie,
December 1876.

1V.—On the Action of Chlorophyll in the Vine.

By Giovanni Briost, Engineer and Director of the Agricultural
Station in Palermo.*

One of the grandest conquests in the realm of modern botanical
physiology, since it concerns the most fundamental phenomenon
of life, is, without doubt, the discovery of the assimilating function
of chlorophyll by which it forms starch out of the carbonic acid
of the atmosphere and water, under the action of the light. As
is known, it was the work of Mohl, Gris, Bohm, Sachs, Nageli,
Kramer, Kraus, &¢., which led to this discovery, which has often
since been confirmed. Consequently it is at present generally
admitted that the starch is, at least amongst the vegetable sub-
stances which are known to us, the primary form of the organic
material of plants, out of which the laboratory of nature derives by
transformations partly understood, and partly unknown to the
chemist, all other physiological allied substances, as sugar, dextrine,
inulin, cellulose, fat, &e.

In another work,j I have pointed out that the product of the
assimilation process of chlorophyll in some plants cannot be starch,

* Translated from the Italian by W. R.
+ Briosi, “ Ueber normale Bildung von fettartiger substanz im Chlorophyll”
(‘ Botanische Zeitung,’ 1873, No. 20 and following ones); also ‘ Nuovo Giornale
Botanico,’ April 1875.
eta

286 The Action of Chlorophyll in the Vine. By Giovanni Briosi.

and demonstrated in fact that in the chlorophyll of the Strelitziz and
Musce, instead of starch, oil or fat is constantly formed, and that in
these plants afterwards, out of those substances, the cellulose, and
the starch itself (which, too, is found in some of their organs), &c.,
originate.

And these Musacex and the Allium cepa, in whose chlorophyll-
grains Sachs could never detect starch, and where it is suspected
that glucose is formed, are the only plants in which (to my know-
ledge at least) it is certain that no hydrocarbon is formed.

Since 1872, whilst studying what substances are formed in the
vine, and what transformations they undergo, I often had occasion
to observe, that in the chlorophyll-grains of this plant no starch is
found, but the knowledge that this well-known and important plant
had already formed the subject of the researches of the most dis-
tinguished scientific men deterred me from prosecuting my labours;
and since then I had no opportunity of taking them up again, as
during the last few years [ have almost been taken away entirely
from my studies.

Having been called upon towards the end of last autumn, by
His Excellency the Minister of Agriculture, to oceupy myself with a
new disease of which we were warned in some vineyards at Favara
(which disease has shown itself at present in the neighbourhood of
Palermo as well, in a vineyard of Count Tasca, and which seems to
threaten serious disaster to our wild vine), I recommenced my re-
searches on the vine, of which, for the moment, I will state the
following facts :

Up to the present, I have never been able to detect even the
slightest trace of starch in all the vine leaves I have examined,
either young or old, in different vineyards and different varieties.

The chlorophyll-grains of the vine, when treated with alcohol,
potash, acetic acid, or iodine (usual method), appear more or less
with hollows, but there never is the slightest indication of a starch
reaction.

Holes and little gutters are also formed in the chlorophyll-
grains, either under treatment with alcohol, or even with distilled
water. When dry, and without applying any reagent, the chloro-
phyll-grains appear (uniform) without any holes or cavities.

The chlorophyll-grains, which are for several days placed in a
saturated solution of bichromate of potash, appear mostly without
holes, but have lost their homogeneousness, and often show in their
interior more or less dark spots. On the other hand, I never found
starch in the mesophyll of the vine leaves hitherto examined by me,
with exception of the enclosure-cells of the stomata, where it is
never wanting. A small quantity of starch only is found in the
vast crivellati and in the strati amilacei of Sachs, and in the
ordinary fibro-vascular bundles.

*

—————

The Action of Chlorophyll in the Vine. By Giovanni Briost. 287

Glucose, too, I have been unable up to the present to ascertain
microscopically in the vine leaves, since I, once only, had precipi-
tated some red grains of oxide of copper in but two cells; if
afterwards there was found glucose, it was in such small quantity
as to be totally insignificant. Of oil or fatty matter, either nothing,
or an insignificant proportion, is found.

The only substance, however, amongst those determinable by
the microscope, which is met with in abundance in the vine leaves,
is tannin. It is found not only in the epidermal cells without
chlorophyll, on both sides of the leaf, but also in all the cells with
chlorophyll ; nay, in the substance of the palissade (palizzata) cells
of the upper part of the leaf, where, by the direct action of the
light, the influence of the chlorophyll must be more energetic than
anywhere else, tannin is most abundant.

From this, and other observations, I will not conclude as yet
that tannin is formed in the chlorophyll-grains of the vine leaf,
well knowing how daring such a conclusion might appear, in-
asmuch as the greater number of researches made with regard to
the share held by the tannin substances in the vegetable economy,
lead us to regard the tannin more than anything else as a secondary
and lesser product, and one of those which, when once formed,
change no more, and remain as inert substances in the cells in
which they originated, without having any share in the formation
of fresh organic substance. At any rate, from researches now
undertaken, I hope soon to be able to say something more positive
on this subject.

One more observation: It is at present generally admitted that
the libro tenero is made up of the texture which is destined for the
carriage of the protein substances, whilst the hydrocarbons and the
fatty matters would be conducted through the parenchyma. This
theory originated with Professor Sachs (to whom vegetable physio-
logy owes so much), and rests mainly on the fact that in the
elements of the first texture only albuminoid substances are found,
and because chemists never have been able to find starch, other-
wise than in an exceptional manner, notwithstanding that the
degree of these triple (threefold) substances can be so very easily
ascertained.

On another occasion * I have shown that in the libro tenero,
and specially in the cribriform vessels, starch scarcely ever is want-
ing, and even that this starch, on account of its most minute
formation, and of the peculiar construction of the said organs,
seems well adapted to be carried from one part of the plant to
another. At present, it is not without interest to know that, in

* Briosi, “Ueber allgemeines Vorkommen yon Starke in den Siebréhren”
(‘ Botanische Zeitung,’ 1873, No. 15 and following ones); also ‘ Nuovo Giornale
Botanico Italiano, April 1875.

288 On Corpuscles of the Cornea, de. By G. I. Dowdeswell.

the libro tenero of the vine, and particularly in the cribriform
vessels, there is undoubtedly found besides starch, also tannin, and
this in great abundance; this fact will help also to account for
the physiological action exercised by this substance in the plant.

I shall soon publish the particulars of the researches alluded to
in the present preliminary communication.

V.—On the Changes of the Fixed Corpuscles of the Cornea in the
Process of Inflammation. By G. F. Dowprswent, B.A.

Puiate CLXXXIV.

Srvce the discovery by Von Recklinghausen of the immigration of
pus-corpuscles into the substance of the cornea in inflammation,
several observers have alleged that proliferation of the fixed cor-
puscles of that tissue also occurs; in other words, that the so-
termed leucocytes are not entirely immigrant, but that some of
them are formed in the inflamed tissues. It is stated by those who
take this view of the process, that in a few hours after the establish-
ment of inflammation the fixed corpuscles begin to alter, that their
processes are partially retracted and thickened, their outline be-
coming more distinct, and that at a later period small spherical
bodies appear in their substance by a process of endogenous cell-

EXPLANATION OF PLATE CLXXXIV.

Group I.
Corpuscles of the Normal Cornea.

Fic. 1.—T wo corpuscles, isolated, of a vacuolated appearance; nucleus indis-
tinct, processes much anastomosing.

Fic. 2.—Two similar corpuscles.

Fic. 3.—A single corpuscle, showing reduplication of nucleus and nucleolus,
and what might be taken for segmentation of its substance.

Fic. 4.—T wo typical normal forms.

Fic. 5.—A single corpuscle, with very large and strongly defined nucleus.

Group II.

Corpuscles of a Cornea forty-eight hours after commencement of inflammation by
application of Nitrate of Silver.

Fia. 6—A group of fixed corpuscles (c) and wander cells (wv). The latter are
seen to be of diversified form and in an active state of cell-division. ‘The appear-
ances which the fixed corpuscles present are all paralleled in the figures of normal
pene and, notwithstanding the activity of the inflammation, as evidenced

y the state of the wander cells, there is no appearance of proliferation nor of any-
thing abnormal in these.

Fic. 7.—A corpuscle with conspicuous nucleus and two wander cells (~) cling-
ing to its processes,

Fic. 8.—Two corpuscles, the one vacuolated and with nucleus distinct, the
other similar to Fig. 3, Group I.

On Corpuscles of the Cornea, de. By G. F. Dowdeswell. 289

formation ; that with the progress of inflammation these changes
increase, the corpuscles losing their stellate form, and assuming the
character of endogenous mother-cells which divide by fission.

These observations have all apparently been made upon corneas
excised and examined in serum or other fluid, or upon lamine of
corneas prepared by the gold method.

Cohnheim and others have denied that the changes are objective,
and attribute all the appearances to an active immigration of leuco-
cytes. A principal objection to this conclusion has been founded
on the grounds that the observations commenced too late, when the
asserted changes had already occurred.

In the ordinary methods of preparation, the appearances pre-
sented during the second and third day of the inflammation are
such as might readily be conceived to arise from proliferation of
the elements of the tissue ; and it is unquestionably matter of great
difficulty to determine with certainty whether this does occur or
not. ‘The purpose of the present note is to describe a mode of in-
vestigating these appearances, by the employment of which satis-
factory evidence may be obtained that the process essentially
consists in the penetration of colourless corpuscles (migratory cells),
in a state of active cell-division, into the cell-spaces of the cornea,
where they overlie and obscure the cornea-cells in such a way that,
in preparations made by the usual methods, they appear to be
incorporated with them. If, however, a method is employed by
which the ground-substance can be destroyed (as e. g. by potash)
and the corpuscles separated by teasing, it is shown that they are
perfectly unaltered, the migratory or wander cells only undergoing
cell-division ; so that it is by the presence of the latter alone that
the difference between a normal and an inflamed cornea can be
recognized.

The appearances presented by these corpuscles in corneas pre-
pared by the ordinary methods, when supposed to be undergoing
proliferation, have been so often described and figured that they
need not be further referred to here.

Methods adopted in these Haperiments.—Inflammation was
induced either by touching the surface with a fine point of nitrate
of silver in the usual way (in which case the ensuing process arrives
at its height in about forty-eight hours,.and then gradually sub-
sides, so that by the fourth or fifth day its effects have disappeared),
or (when it was desired that the process should be of longer dura-
tion) by a seton of silk thread. The animal having been killed at
the proper period, and its cornea excised and immersed in half per
cent. solution of gold chloride for sixty minutes, and exposed in a
light warm place, when sufficiently coloured a small portion of the
inflamed part is placed in a solution of potash till the ground-
substance 1s completely dissolved. Care is requisite to hit off the

290 On Corpuscles of the Cornea, de. By G. F. Dowdeswell.

exact point for this, a few minutes too much or too little rendering
the preparation useless. If the time of exposure is too short,
obviously the ground-substance is not wholly dissolved, and nothing
is seen; if it is too long, the potash begins to act upon the pro-
toplasm, and the corpuscles cannot be separated nor distinguished.
It was found that, if the cornea was put into a 20 per cent.
solution of pure potash cold, and then subjected to a temperature
of 40° C., fifty minutes was the proper time required for the action
of the potash.

When sufficiently acted upon, the cornea is transferred to
slightly acidulated water, to stop any further action of the potash,
then placed on a slide, if necessary teased out lightly, and pre-
served in glycerine.

Ina preparation made by the above methods, a number of migra-
tory cells will be apparent under the microscope, some of which
are entangled amongst the processes of the fixed corpuscles. All
these are in a state of active cell-division and assuming diversified
forms, but are very readily distinguished from the fixed corpuscles
by their being devoid of processes, of somewhat darker colour, and
by their presenting a more opaque and solid appearance.* The
fixed corpuscles, with their processes, show no alteration whatever.
As may be seen from the Figures (Plate CLXXXIV., Group II.),
the processes radiate from the bodies in a natural and symmetrical
manner, and the ramifications are as perfect as ever. This would
certainly not be so if segmentation had occurred; for in that case
one side at least of each newly divided corpuscle would be devoid
of processes. Nothing approaching to such a condition is ever
seen. In inflamed preparations, as in normal ones, fixed corpuscles
are occasionally met with containing two nuclei or a double.
nucleus; but this appearance is not often seen, and not more fre-
quently in later than in earlier stages.

In conclusion, it may be stated that in the whole number of
successful preparations of corneas which have been examined
(amounting to upwards of twenty), no single instance has occurred
in which any distinct appearance of segmentation can be made out.
The most careful scrutiny of the preparations fails to detect any
difference whatever, as regards their forms or aspects, between the
fixed corpuscles of inflamed corneas and those of normal corneas —
prepared in a similar way; nor would it be possible to distinguish
preparations of the two classes from each other, were it not for the
presence of migratory cells in the inflamed structure.

In the drawings representations are given both of normal pre-
parations (Plate CLXXXIV., Group I.) and of others at the most
active period of inflammation (Group IJ.). These have all been
most carefully drawn under the camera, each fibre and line being

* This is not adequately shown in the drawings.

TheMonthlyMicroscopical Journal June 1.1877. Pl. CLXXXIV.

Group I

~~ West & Co lith,

Corneal corpuscles.

Group],normal,— group Zintlammatory.

“

On the Teeth of certain Ruminants. By M. V. Pietkiewicz. 291

actually copied as they appeared in setw in the field of view of the
microscope, some processes and other bodies being omitted for
the sake of clearness, and the peripheral members of the group
sometimes brought nearer to the centre to save space. Numerous
other preparations were made at all stages of inflammation, com-
mencing with five hours, when little or no change was observable,
up to five and seven days, when, in the case of inflammation
induced by nitrate of silver, the effects had passed off, leaving no
recognizable traces.—Proceedings of the Royal Society, No. 177.*

VI.—Goodsir’s Arguments on the Development of the Teeth of
certain Ruminants. By M. Y. Prerximewicz.

In a communication made to the British Association in 1839
Goodsir announced that he had discovered in the jaw of the calf
and sheep the germs of incisor and canine teeth, and even of a
molar, intermediate between an abortive canine and the ordinary
molars which exist in these animals. Geoffroy Saint-Hilaire had
already described abortive dental germs in the lower jaw of the
baleen whale (Balena mysticetus). Naturalists, partisans of the
theory of Lamarck, and of Evolution, Darwin particularly, seized
hold of this idea; and thus associating the discoveries of compara-
tive anatomy and paleontology, this embryological discovery per-
mitted the association of groups of animals which had before been
separated.

Everyone knows the difference which exists between the dental
formula of ordinary ruminants, as the ox and sheep, whose formula
is 1} C$ M &, and the formula of the omnivorous pachyderms, the
hippopotamus and the wild boar (le Sanglier),I13C1Mz. But
all authors have found the presence of superior canines in two or
three genera of ruminants, the deer and the goat, which have a
formula of I$ C+ M €, and the existence of a pair of very distinct
upper incisors in the camel (chameau) and lama (Jamas), giving the
formula 1} C} M&. According to M. Paul Gervais these latter
had even two pairs of upper incisors, one of which disappeared in
the adult, but was present in young animals, so that they would
have this formula 1? C+ M&; this author does not doubt either ~
that if the animal was examined at a younger age stili, one would
find a third pair of incisors in them, and thus that their dental
formula would be related to that of pachyderms minus one molar:
I3C{}Mé&. Then, on the other side, the study of fossil species
has shown that the Dinotheriwms and the Amphitragalus, con-
sidered as ruminants of the group of Chevrotins, have seven molars

* Professor Huxley has kindly given permission for its reproduction here.—
Ep. ‘M.M.J.’

292 On the Teeth of certain Ruminants. By M. V. Pietkiewiez.

as the wild boars (Sangliers) have, that is to say the same number
as the pachyderms. Thus, among the ruminants, we already know
of fossil species having the same dental formula as the pachyderms,
and of living species whose formula is almost identical; the dis-
covery of Goodsir, by giving to ordinary ruminants, such as the ox
and sheep, at a certain period at least of their lives, the same for-
mula as that of pachyderms, permits us to associate these two
groups. One set of naturalists sees in this one of the results of
their hypothesis upon the unity of plan in nature. Another set
sees in it a confirmation of their transformist theories, and explains
the abortion of these organs by their non-usage, and the successive
confirmation of this anomaly by “ adaptation” and “ heredity.”

I was therefore surprised when, in endeavouring to verify an
opinion which was so creditable to science, I found nothing what-
ever to justify it. In a long series of preparations made upon the
embryos of the ox and the sheep from the earliest period of em-
bryonic life to the period when the foetus is 30 centimeters long in
the sheep, not only have I never found the presence of follicles,
but I have not even found a trace of the epithelial lamina, the
beginning of all follicular development.

Goodsir’s error was conceived through the false notion he had
formed of the development of the follicles, and in the commence-
ment of my investigations I had the same idea. In sections made
properly at the anterior part of the upper jaw of the ox or sheep
one finds in fact on each side of the median line an epithelial sac,
which detaches itself from the buccal mucous membrane to bury
itself in the jaw. The mucous layer of Malpighi uninterrupted forms
itself an external lamina, whilst on its interior is found a polyhedric
epithelium like that of the middle layers of the buccal epithelium.
Thus formed this little sac appears to constitute the commencement
of the follicle as Goodsir imagined it. But in continuing to make
on the same jaw a series of sections going farther and farther from
the anterior part, one sees the little sac lose its relations with the
buccal mucus, and take the form of a circular canal for the mucus
of the nasal fosse. Soon appears around this canal a cartilaginous
belt, then at its upper part is a pad (bourrelet) containing vessels,
and then one has before him Jacobson’s organ as Gratiolet
described it. There is then nothing that can be compared even
distantly to the germs of canines and incisors. If it is possible to
conceive of Goodsir’s error in face of the little epithelial sae pro-
duced by section of the buccal extremity of Jacobson’s organ, one
finds nothing to justify him in affirming the presence of three
incisors, of one canine, and of one molar tooth in this region.—
Comptes Rendus, March 12, 1877.

PROGRESS OF MICROSCOPICAL SCIENCE.

The Structure and Origin of Meteorites—It may perhaps seem very
strange to speak of the microscopical structure of the sun; but if
meteorites have been formed in the manner suggested in Mr. Sorby’s
lecture, published in ‘Nature’ for April 5, such an expression may
not be unreasonable. He there shows that the microscopical structure
of meteorites, though in some cases analogous to that of melted lavas,
is yet in a greater number of cases more like that of consolidated vol-
canic ashes. They have, however, some remarkable characters not yet
found in any terrestrial rock, which indicate that they were formed
under very special conditions. They frequently contain what were
apparently originally small glassy spherules, which subsequently be-
came more or less crystalline and devitrified. A large portion of some
of these spherules is, however, still a true glass. The author shows
that they are analogous to certain artificial furnace-products, but differ
in such a way as to indicate that a melted glassy spray was projected
into an atmosphere heated so nearly to its melting point that the par-
ticles could collect into spheres without being drawn out into long
fibres, as happens when the spray is blown into a cool atmosphere, so
as to form the natural Pele’s Hair, or the analogous artificial furnace-
product. Many other remarkable structures occur in meteorites, some
requiring high magnifying powers ; and the general conclusion deduced
from them is, that meteorites were formed when the surrounding at-
mosphere was highly heated and subject to intense mechanical dis-
turbances. Nearly all these remarkable peculiarities could be explained
if they were formed under conditions like those now proved to cecur
near the surface of the sun, and the chief question is whether they are
portions of solid matter, perhaps now projected into space during the
intense disturbances known to occur on the surface of the sun, or are
remnants of matter subjected to similar influences at a remote epoch
when the conditions now met with only near the sun extended much
farther out into planetary space. If this be the case, it is perhaps not
too much to say that the microscope was never applied to a question
of greater magnitude, and the important bearing of very minute on
immensely great objects made more apparent.

Mr. Dallinger’s Lecture on Monads at the Royal Institution—On
the first Friday evening of last month (May), the Rev. W. Dallinger,
V.P.R.M.S., delivered a most important lecture on monads before the
Royal Institution. The illustrations were given by means of the
electric lamp so familiar to those who go to the Albemarle theatre,
and they were in every respect admirable. The lecture, however, was
in substance similar to Mr. Dallinger’s excellent article in one of last
year’s numbers of the ‘ Popular Science Review.’ He proved the mar-
vellous changes of form seen in some of these species of monads to be
continuous alterations which invariably ended in the production of
the original type. This he did by the most wonderfully patient
observations. He also proved—a most important poit—that there

294 PROGRESS OF MICROSCOPICAL SCIENCE.

was a difference in the power of resisting high temperatures exhibited
between the mature and young forms of monads. This fact is of in-
finite importance, as it tends to overthrow Bastian’s notions.

The Diatom Earth of Richmond, U.S.A.—This subject has been
discussed in an opening article (by Mr. C. L. Peticolas) in a late
number of the ‘ American Journal of Microscopy.’ It says that to the
microscopist this deposit is a source of unfailing interest, whilst the
most inexperienced in such matters, upon being shown the wonderful
forms found in it, are struck with surprise and delight. In looking
at these different forms, one is struck with the wonderful resemblance
which they bear to things of every-day use, as among them may
be found models of almost all the implements used by savages,
whether for war, the chase, or in domestic life; witness, for instance,
his stone hatchets, arrow and spear heads, knotted clubs, boomerangs,
&c.; a catalogue of such matters used by civilized people would
embrace plates, dishes, cups, saucers, gridirons, pins, balls, tops,
spectacles, watches, anchors, dumb-bells, cannon, coin, musical notes,
and many other articles—the investigator being constantly startled
by the strange resemblance which hundreds of these ancient natural
forms bear to articles used in our houses and workshops. Certain
varieties, however, predominate, and their distribution varies with
level and locality, the upper portion of the stratum being compa-
ratively poor in forms, while they increase in number and variety as
we descend to the middle, falling off again towards the bottom. The
genus Coscinodiscus seems to characterize this earth, and of it there
are dozens of varieties varying from the (microscopically) enormous
C. gigas to the minute and elegant C. subtilis, which resembles closely
a finely polished opal, requiring a lens of wide aperture and consider-
able power to show its revelations. Orthosira marina is abundant,
whilst many beautiful forms of Navicula are found in every gathering.
Amongst these we may note two kinds of Pleurosigma, one of which,
P. angulatum, is a favourite test-diatom, and the other, which it is pro-
posed to call P. Virginica (as it is the most common form of Plewrosigma
in the Virginia earths), is remarkable for the beauty of its contour,
which exactly copies a willow leaf, and the want of uniformity in its
strie, which are much coarser in the middle than at the ends of the
valves. It is easily resolved with a }-inch objective, without the aid
of oblique light. The genus Triceratium is also well represented by
many beautiful varieties, the most interesting of which is T. obtusum,
which can be resolved as easily as P. Virginica. Isthmia enervis, Bid-
dulphia Turmegti, Terpsinoe, Musica, Aulacodiscus crux, Navicula lyra,
Gonphonema, Heliopelta, Asterolampra concinna, Asteromphalus Brooketi
and Synedra are comparatively rare. From the great variety of its
species, and the wide range in the character of their markings, the
Richmond earth forms one of the best and most interesting tests
for the performance of objectives of almost every power. On some,
for instance, the areolations may be seen with a simple triplet, magni-
fying 25 linear; on others a first-class twelfth or sixteenth of wide
angular aperture, aided by all the modern refinements of illumination,
is needed to show them.

PROGRESS OF MICROSCOPICAL SCIENCE. 295

Starch in Granules of Chlorophyll.—According to a contemporary,
Bohm asserts that if light is sufficiently intense to induce assimilation
in green leaves, it has the power to cause an immediate transfer of
starch from the stem, where elaborated matters may be stored, to the
chlorophyll granules. For this reason he believes that many observa-
tions hitherto made in regard to the immediate production of starch
from carbonic dioxide in chlorophyll are untrustworthy. Such experi-
ments should be made upon plants which have no starch already stored
up, or upon detached leaves which contain no starch.

Reproduction in the Ascomycetes Fungi.—A paper on this subject has
been contributed by M. Maxima Cornu to the ‘ Annales des Sciences’
(1876, page 53), and it is given in lengthy abstract in a recent
number of the ‘Journal of Botany.’ It states that the term “ sper-
matia” has hitherto been applied to conidia-like bodies collected in
special cavities, and thought to be incapable of germination. Tulasne
had in some instances observed germination of bodies similar to sper-
matia, but where budding did not result, instead of doubting the
perfection of his cultural methods, he believed he had to do with
sexual elements, and to these he applied the special term. By adopt-
ing a system of culture somewhat similar to that made use of by
Van Tieghem and Le Monnier in their researches on Mucorini,
M. Cornu has succeeded in causing germination of many spermatia.
The most satisfactory results were obtained when the nutritive liquid
consisted of distilled water with 1 per cent. of sugar and 0-4 per cent.
of tannin, though in a few instances simple water was the most ad-
vantageous medium of growth. With these results in hand, M. Cornu
thinks it permissible to suppose that all spermatia are capable of
germination if a suitable liquid can be found for each case ; it becomes
necessary, therefore, to consider the relations of spermatia to the
similar reproductive bodies known as stylospores and conidia. Their
main point of difference from stylospores resides in the fact that the
membrane of the latter is usually double, while, unlike conidia,
spermatia are collected in special cavities. MM. Cornu thinks that
terminology is here too exuberant, and he proposes the elimination
of the term “ conidium,” referring thick-membraned conidia to a
place among stylospores, and thin-membraned to spermatia. He also,
following out Bonorden’s suggestions, expresses his belief that certain
Mucedines—e. g. Verticillium, Acrostalagmus, Dendrochium, &c.—are
spermatia-bearing forms of Ascomycetous genera near Hypomyces ;
other Mucedines he would refer to Peronosporeee and Mucorini. With
regard to the function of spermatia, M. Cornu shows that, being very
small and produced in great numbers, they are capable of causing
wide diffusion of the species, the difficulty of germination being an
additional advantage in diffusion, since the chances are considerable
that before they reach a suitable nidus some time must elapse, during
which they may be transported by the agency of winds, birds, &e.

The Lymphatics of the Joints.—Dr. Stirling states in the ‘ Medical
Record’ that Herr H. Tilimanns contributes an essay on this subject
to the ‘ Archiv. fiir Mikros. Anat.’ (Band xii.) It would seem that

296 PROGRESS OF MICROSCOPICAL SCIENCE.

the lymphatics of tendons, fascie, and serous membranes can very
conveniently be injected by flexing and extending these parts. The
joint of a newly killed dog was filled with a coloured fiuid, and
the limb flexed and extended, but no colouring matter entered the
lymphatics. This would seem to show that absorption from the
synovial surface takes place in a way different from that which
obtains in the case of serous membrane. By the puncture method,
however, Tillmanns easily succeeded in injecting with a 0°5 per cent.
solution of silver or soluble Berlin blue, a very rich network of
lymphatics lying immediately under the epithelium and also in the
subsynovial connective tissue. This he did in the large joints of
the ox and horse. The superficial lymphatics lie directly under the
epithelioid layer, deeper than the finest capillaries, but superficially
to the large arterial and venous branches. The author finds that the
blood-capillaries do not project bare into the joint, but are covered
by the epithelioid layer. No lymphatics were found in the villi of
the joints. The superficial subepithelioid lymphatics communicate
with very wide vessels lying in the subsynovial tissue, where the
lymph-vessels are very numerous and not unfrequently surround
the blood-vessels. The vessels can be most easily injected where the
synovial membrane joins the base or cartilage. No lymphatics pass
from the synovial membrane, either into the subjacent bone or carti-
lage. The microscopic structure of the lymphatics was studied by
Stirling’s method, viz. digestion in artificial gastric juice. It seems
that the epithelioid lining of the lymphatics is directly continuous
with the elastic tissue of the adjacent tissue, thus fixing the lym-
phatics. The lumen of the vessels will thus be kept patent by the
elastic fibres, and may even be dilated when the fibrous tissue becomes
swollen. This bears out some suggestions already made by Ludwig
under normal circumstances.

Remarks on the Structure of Precious Opal.—Professor Leidy,
according to ‘Silliman’s American Journal’ for April, has an article
in the ‘ Proceedings of the Academy of Natural Sciences of Phila-
delphia’ for 1876, p. 195, on the microscopic structure of the opal of
Queretaro, Mexico.

Structure of the Red Blood-corpuscle of Ovipara.—Mr. Gulliver
sent a note on this subject to a late meeting of the Hast Kent Natural
History Society. It is conceivable, he wrote, that there may be an
essential difference between the corpuscles of batrachians and fishes ;
so that, granting the truth of his own and Mr. Hammond’s obser-
vations on the presence of the nucleus in the living corpuscles of this
class, the validity of Professor Savory’s observations on the absence
of the nucleus of the living corpuscles of frogs and newts would not
be necessarily destroyed. And then the question would only be like
that which was so much agitated upwards of a quarter of a century
ago, concerning the structure of these corpuscles throughout the ver-
tebrate sub-kingdom. At that time one party, following Hewson,
declared that the nucleus is quite distinct; while another party, with

PROGRESS OF MICROSCOPICAL SCIENCE. 297

Dr. Young, Dr. Hodgkin, and Mr. Lister, maintained that there is no
nucleus. But the subsequent researches of Mr. Gulliver had proved
that the disputants on both sides were, as in the fable of the chame-
leon, both right and wrong; for the regular blood-disks of mammals
are destitute of a nucleus, while those of the lower vertebrates are
regularly nucleated. And hence his two great divisions of vertebrates
—Apyrenemata and Pyrenemata.

The Blyborough Tick.—At the above Society, referring to the plates
and engravings of this tick, lately published with descriptions in the
‘Journal of the Quekett Microscopical Club,’ and in ‘ Science-Gossip,’
it was stated that specimens received from Blyborough had been for-
warded from Canterbury to Oxford, and declared at that University to
be identical with a species described and named Argas pipistrelle, by
Professor Westwood, in the ‘ Proceedings of the Entomological Society
of London,’ for the year 1872.

The Microscopical Active Principle of the Cobra Poison.—An inter-
esting paper in which the chemistry of cobra poison is exhaustively
dealt with, appeared lately in a paper termed the ‘ Analyst, from the
editor of which we have obtained the blocks used to print the figures
over leaf. These representations are figures magnified 250 diameters
of cobric acid, of which the following account is taken from an essay by
Mr. W. Blyth, M.R.C.S., that appeared in the ‘ Analyst’:—“On the
1st of January of this year, I succeeded in obtaining a crystalline, acid,
extremely poisonous substance, which appears to be contained in the
venom to the extent of 10 per cent.; this substance, there is every
reason to believe, is the sole and only active principle. It may be
obtained by coagulating the albumen with alcohol, filtering, driving
off the alcohol at a gentle heat, concentrating the liquid to a small
bulk, precipitating with basic acetate of lead, collecting the precipi-
tate, washing it, and subsequently decomposing it in the usual way by
SH.,, removing the sulphide of lead, evaporating to a small bulk at
a gentle heat, and finishing the evaporation spontaneously or in a
vacuum, or it may~be obtained by coagulating and separating the
albumen as before, shaking up in a tube with ether, removing the
ether in the usual way, evaporating the ether off, redissolving in
water and passing through a wet filter to separate fat, and evaporating
as-before; in either case the result is microscopic needles, dissolving
in water with an acid reaction and possessing highly poisonous pro-
perties; they appear to be identical with the needles obtained by
sublimation.

“For this substance I provisionally propose the name of cobric acid.
I have not been able to go as yet any farther in the investigation of
this interesting substance, for the simple reason that my two very
small supplies are now exhausted, and I must wait for a third packet,
but it will not be uninteresting to pause for a moment to consider
what a terribly active substance this cobric acid must be, for sup-
posing Nicholson’s data are correct, and that the whole of the average
quantity of the venom (that is 6 grains, containing 2 grains of solids)

298 PROGRESS OF MICROSCOPICAL SCIENCE.

is injected into a man, it t!:en follows, since the solid residue contains
10 per cent. of cobric acid, that one-fifth of a grain would be fatal, so
that we have here a rival to aconitia weight for weight in its power
of destruction.”

t
\i |

Cobric Acid magnified 250 diameters.

The Blood-vessels of Muscle under the Microscope.—Mr. W. H.
Gaskell has recently presented a paper on this subject to the Royal
Society, in which he describes the results of observations made on the
living blood-vessels of the mylohyoid of the frog. He says he found
that the mylohyoid muscle was the most suitable one for his purpose,
it being easy to prepare it for microscopic observation without da-
maging the circulation through it, and, in fact, without even touching
the muscle; whilst, owing to its thinness, the small amount of con-
nective tissue in the neighbourhood of the vessels, and the absence of
pigment-cells, it is possible here to measure with a micrometer eye-

PROGRESS OF MICROSCOPICAL SCIENCE. 299

piece the diameter of vessels more accurately and easily than in any
other preparation. Upon placing this muscle under the microscope,
without having previously touched the nerve, it is seen that the cir-
culation presents much the same character as in the web, the median
red-corpuscle stream with an inert layer on each side being plainly
visible, although, perhaps owing to the manipulation, the arteries at
first are slightly fuller and more dilated than the corresponding vessels
in the web. The calibre of the smaller arteries does nof, as a rule,
remain for any length of time the same, variations taking place some-
what similar to what has often been described in the vessels of the
web, but with this difference, that whereas in the so-called “rhythmic
contractions” of the arteries in the web the artery appears to contract
to a certain point and then to return to its original calibre or beyond
it, in the arteries of the muscle the vessel appears to dilate from
the normal calibre, and then gradually to return to that calibre or
below it. These dilatations vary considerably in extent and are abso-
lutely irregular in time, being much less marked both in frequency
and extent in some frogs than in others, and depend, so it seems
to him, probably upon some chance stimulation of the vessels, such as
exposure to the air, &e. Upon direct stimulation of the web by means
of the interrupted current there occurs a most marked constriction,
not only of the arteries between the electrodes, but extending over the
whole web, both during the stimulation and for some little time after
the stimulation is over. He goes on to say, ‘“ Whether the arteries
immediately between the electrodes contract, I cannot yet say; I can,
however, affirm positively that there is no contraction of the smaller
arteries situated but a slight distance from the electrodes, or if there
is, it must take place in the very short space of time necessary for
refocussing on the artery under observation, as in every Case, as soon
as I have been able to measure the calibre again, I have found it con-
siderably dilated. Here, then, is a marked difference between the web
and mylohyoid on direct stimulation. As to the effect of section of the
nerve, I have always noticed that it is followed by a decided reddening
of the corresponding muscle, the difference of colour being manifest, as
previous to the section the two mylohyoid muscles are always equally
pale. Upon closer examination, by first putting the muscle in position
under the microscope and then cutting the nerve, it is seen that about
five to six seconds after section the arteries dilate very rapidly, the dila-
tation soon reaching a maximum, in perhaps twenty or thirty seconds,
and then gradually diminishing until the original calibre is reached,
some four or five minutes after section—that is, the dilatation caused by
section of the nerve is not a lasting one, but is exceedingly similar to
that caused by slight mechanical stimulation of the nerve ; for whether
its peripheral extremity is pinched by a pair of forceps, or dipped into
concentrated salt solution, or still more markedly when cut and torn
by scissors and forceps, there always occurs after a brief latent period
of a few seconds, during which there is no trace of constriction, a con-
siderable rapid dilatation of the artery, which lasts but a short time,
and then gradually gives way to a return to the original calibre, and
is always accompanied by a more active very full stream, the inert
VOL. XVII. Z

3800 PROGRESS OF MICROSCOPICAL SCIENCE.

layer having wholly disappeared, and the red corpuscles being crowded
together to the very edge of the vessel. Here, then, is another marked
difference between the web and the muscle.” *

Mr. Lewis’ Freezing Microtome.—The adjacent cut represents this
instrument, which Mr. Bevan Lewis, F.R.M.S., has described at some
length in the ‘Journal of Anatomy’ (vol. xi.), and which is not so
novel as he seemed to think at first. In fact, he states at the conclu-
sion of his paper that he then became aware of a previously described
instrument by Mr. Hughes; but he says that in his (Mr. H.’s) micro-
tome, the spray is not so directly brought to bear upon the tissue,
which consequently requires from five to eight times as long a period
to freeze, with, of course, a corresponding increase in the loss of ether :
this is of material import when absolute anesthetic ether is em-
ployed. He states that “the instrument consists of three portions:
(1) an ordinary Stirling’s microtome; (2) a section plate; (3) a
freezing and condensing chamber. The simplicity of the arrange-
ment will, I trust, recommend its use amongst my fellow-workers in
the department of cerebral histology. Reference to the accompanying
woodcut will place the reader in possession of the plan upon which

H

this instrument has been constructed. The section plate (a) is riveted
by a brass arm to the microtome (b). The freezing compartment (c)
consists of a cylinder (d) and a condensing chamber (e), the latter
being formed of brass with a sloping floor leading to the exit-tube,
which is provided with a stop-cock (f). The cylinder is capped with
tin-foil stretched across it, and has an orifice (d) through which the
nozzle of the spray apparatus is introduced. In using this instru-
ment it is only necessary to bring down the cap of the cylinder from
one-fourth to three-eighths of an inch below the level surface of the
section plate, and to place in it a section of brain of about the same
thickness. The spray instrument is inserted at the orifice,and by the
ordinary double elastic balls a free play of ether beneath the cap
freezes the tissue in from twenty to thirty seconds or less. On with-
drawing the spray instrument, the slight play of ether, still continuing
from the remaining tension of the elastic ball, is utilized by being

* “Proceedings of the Royal Society,’ No. 176.

PROGRESS OF MICROSCOPICAL SCIENCE. 301

carried rapidly along the surfaces of the section blade, and then the
finest possible sections may be cut with great ease. The consistence
of nervous structures, when thus frozen, is really exquisite for section
cutting, and the tissue remains rigidly adherent to the capped top of
the cylinder. Perfect steadiness of the freezing chamber is ensured
by soldering it to the microtome plug, and it can be readily removed
from its position by throwing back the section plate, a movement
allowed for by the hinge-joint (#).”

The Siliceous-shelled Bacillarie in Diatomacee.—These are being
described in the ‘American Journal of Microscopy’ (March and
April),* from papers which originally appeared in the ‘ Lens,’ and
which were translations by Professor Smith, of Kiitzing’s work on the
Bacillarie. Strange to say, however, there is no notice of either
author or translator attached to the paper itself. But in another
part an editorial note explains this fact. To those who are unfamiliar
with the original work, this translation must prove of interest. The
last passages in the April number contain a very decided but well-
merited attack on Ehrenberg for his habit of disregarding the work
of others in establishing species.

Reproduction of Rotifer vulgaris—An American, Mr. C. F. Cox,
has been studying this subject with some success. He says that
“My attention was called to the process of reproduction by seeing,
in the larger rotifers, an extra ‘gizzard’ below the one to which
each individual seemed properly entitled, and by observing the in-
dependent movements of the imprisoned embryos. But a simple
egg-shaped vacuole-like ovum is to be seen in every rotifer, even at
its birth, I believe. Subsequently the embryo develops its ciliated
lobes, its proboscis, its eyes, and its foot or leg, and for a short
period before birth a slight ciliary movement may be seen, and
a slow working of the gizzard. At this time its head is close to
the gizzard of the parent, and the appearance is as if the fetal
rotifer were actually sharing the food of the mother and remas-
ticating it. This, however, finally ceases, and the foetus, generally
with some difficulty, turns itself within the parent, in order to present
its head first at the time of parturition. If the operation is inter-
rupted, or the parent much disturbed, the foetus may turn back again,
and this vacillation is in many cases repeated several times before
birth is effected. Some writers state that the nascent rotifers ‘creep
out of their envelopes, extend themselves, and put their wheels in
motion, while within the ovary, but I am convinced that motion of
the ‘ wheels’ is impossible at this time, both from the size and from
the position of the young, and the rest of the statement quoted seems
to me highly imaginary. The slight ciliary motion observable at this
time is produced, I think, not by the large cilia upon the infolding
head-lobes, but by a ciliary system lining the throat of the animalcule,
analogous to the ciliary system which I have discerned in the throat

* By the way, there appears to be some irregularity of publication about this
journal. We have only to-day, May 8, received the number dated April. Is it
published at the end instead of the beginning of the month?

a2,

302 PROGRESS OF MICROSCOPICAL SCIENCE.

of Floscularia. From this motion’s being seen so plainly in the
nascent rotifer, I am inclined to believe that it is by this means that
food is taken from the parent’s supply, as already suggested. The
movements of the foetus do not seem to trouble the parent in the least
degree, although she is, as usual, extremely sensitive to any external
motion. The whirling of her cilia and the working of her gizzard
are interrupted by the reproductive process only at the very instant
of parturition. The ovarian sac opens into the cloaca, or rectum, of
the rotifer, and the young is extruded from the anus, which is just at
the lower edge of the upper segment of the foot-stalk or leg, and is what
is rather indefinitely fermed, by some authors, the ‘ contractile vesicle.’
At the critical moment the parent draws herself violently together,
so as to force the head of the young rotifer through the anus, and
then the latter actively liberates itself and crawls away. At first it
is somewhat awkward and undetermined in its movements, but, after
creeping about for a few minutes, it attaches itself to some fixed
object and opens out its ciliary wreaths, which it whirls as accurately
and as gracefully as any old animalcule could do. Frequently a
mother rotifer, containing a well-advanced embryo, also contains
several partially developed ova, one of which may be seen to be
' undergoing a sort of segmentation or differentiation, the gizzard
being about the first organ to make its appearance. I have several
times seen a large rotifer, which had been killed in some way, lying
drawn up into a rounded mass, in which a lively young one was
making frantic but ineffectual efforts to break through the envelop-
ing corpse and escape. This suggests the conclusion that the de-
velopment of the foetus, after it has reached a certain point, is
dependent upon the parent only for food; and this supports my
belief, already expressed, that the foetal rotifer actually and actively
feeds, and does not merely passively imbibe. On seeing so many
rotifers containing young as I have happened upon in the last few
days, I am astonished that their reproductive process has not been
oftener the subject of observation and description than it seems to
have been. All the rotifers I now see are in the interesting con-
dition described, and yet, according to ‘ the authorities,’ no males of
Rotifer vulgaris have ever been discovered. Analogy, however, seems
to indicate that this rotifer, like Hydatina, Brachionus, Melicerta,
Floscularia, &c., is dicecious. The earlier steps in its mode of repro-
duction are, therefore, an inviting subject for investigation. By the
way, why do Pritchard, Carpenter, and others, persistently describe
and draw Rotifer vulgaris with spined or hooked margins to the
segments of the foot-stalk or leg? I think I have never seen it with
such segments. The foot-stalk, as far as I have observed, is simply
telescopic, like that of Acéinurus, and consists of more segments than
are usually drawn or described—probably six. Can it be that there
is a difference in these respects between the common rotifer of
England and that of this country ?”

A Tape-worm in a Cucumber (/).—It is stated that at a recent
meeting of the Academy of Sciences, at Philadelphia, Dr. Leidy
exhibited a specimen of a tape-worm said to havé been taken from the

ee

PROGRESS OF MICROSCOPICAL SOIENCE. 303

inside of a large cucumber. This was the first time he had heard of
one of these worms haying been found in a vegetable. It had all the
characteristics of a true tape-worm, but belonged apparently to an
unknown species. The ovaries, containing round yellow eggs, were
confined to the anterior extremity of the segment. [The ova of the
mature worm may have been deposited in the manure with which
these plants are so freely surrounded, and it is remotely possible that
some one of them may have got in through some crevice in the plant,
and may then have begun its development as though it had got into
a mammal’s stomach, It is certainly difficult to understand. |

The Structure of the Brachiopoda.—This is very well given in a
series of papers in the April and May numbers of the ‘ Geological
Magazine, by our most distinguished Brachiopodist, Mr. Thomas
Davidson, F.R.S. King’s, Hancock’s, Owen’s, Morse’s, Gratiolet’s,
and Deslongchamps’ views are fully discussed by the author.

Carboniferous and Permian Foraminifera.—The volume of the
Monographs of the Paleontographical Society for 1876 contains an
important essay by H. B. Brady, entitled “A Monograph of Car-
boniferous and Permian Foraminifera,’ the genus Fusulina being
excepted. This has been well reviewed by a most distinguished
Foraminifer authority, Professor T. R. Jones, F.R.S., in the
May number of the ‘Geological Magazine. We give here the
portion of interest to the microscopist :—‘ The ‘ Zoological Con-
siderations,’ of especial interest to the Rhizopodist, comprise a critical
review of von Reuss’ and Carpenter's classifications of Foraminifera,
and a general comparison of the generic forms known in the Car-
boniferous strata with those now living. The conclusions arrived at
are—l,. The prevalent forms (except Fusulina) in the Carboniferous
and Permian limestones do not belong strictly to either of the two
sub-orders (Imperforata and Perforata) into which Foraminifera have
been divided, but to intermediate types (especially Trochammina,
Valeulina, Endothyra, Nodosinella, and Stacheia), neither invariably
arenaceous nor uniformly perforate in their shell-texture. 2. In the
modifications of these primitive intermediate types there are some
varieties conspicuously sandy and imperforate, others essentially
hyaline and porous; and these varietal peculiarities seem to have
been transmitted as permanent characters, thereby originating the
two parallel isomorphic series. 38. The porcellanous imperforate
group (Miliolida) is of later creation, judging from negative evidence.
4, The Permian Rhizopod-fauna is much more limited than the Car-
boniferous, being confined to five generic types (Trochammina, Nodo-
sinella, Nodosaria, Textularia, and Fusulina), representing, however,
at least four distinct families of Foraminifera, which in the Car-
boniferous rocks are represented by fifteen genera.” More than
twenty genera and many species are described and figured, and after
naming them in their order, Professor Jones concludes as follows :—
“The exposition of the structure of Valvulina and Endothyra and their
interesting subarenaceous allies, already noticed, and the discovery of
the Rotaline (Truncatulina, Pulvinulina, Calcarina), and of the Num-

3804 PROGRESS OF MICROSCOPICAL SCIENCE.

mulinide (Archediscus, Amphistegina, and Nummulina), m the Car-
boniferous limestones, are some of the most important points in this
excellent Monograph; and its value is greatly enhanced by eight
elaborate Tables, special and general, showing in great detail the
geological and geographical distribution of the fifty-eight species,
according to their localities and stratal horizons in the many districts
whence they were obtained. A perfect index for genera and species
and their synonyms completes the volume.”

British Fossil Bivalved Entomostraca of Post-Tertiary and Car-
boniferous Dates.—These have been thoroughly worked out and figured
in sixteen plates in the ‘ Monographs of British Fossils, * by Dr. G. 8.
Brady and Messrs. H. W. Crosskey and Dr. Robertson. Of it the
‘ Geological Magazine’ (May) says:—‘ The classification of the
Ostracoda (the special group of Bivalved Entomostraca treated of in
this Monograph), according to the shape, texture, markings, and hinge-
ment of the valves, and the synopsis of their genera, based upon the
anatomical characters of the animal, will be highly acceptable to the
students both of recent and of fossil specimens ; and indeed these
admirable synopses are full of the latest information, derived from
the researches chiefly of Dr. G. O. Sars, of Norway, and Dr. Brady
himself. ‘Of the 182 species of Ostracoda described in this Mono-
graph, 24 may be considered to have been inhabitants of fresh or
slightly brackish water, the remaining 108 being strictly marine
species. All except Limnicythere antiqua are known in the living
state. Of the marine forms found in the Post-Tertiary beds there are
lists given,—1. Of those now known as characterizing the Arctic seas
and the northern coasts of Norway, Scotland, and America. 2. Those
now extinct, or unknown in the living state. 3. Those found in the
Glacial and Post-Glacial deposits of Norway. 4. Those found in
the Glacial (and Post-Glacial ?) deposits of Canada.”

The Carboniferous Entomostraca have been handled by Professor
Rupert Jones, J. W. Kirkby, and G. 8. Brady, in the same volume,
and their observations extend only to “the Cypridinade and their
Allies.” “Some parts of the Mountain Limestones of various countries
seem to abound in subglobular bivalve carapaces, and their loose
valves, which approximate in character to various members of the
Cypridinad group; some are also found in the Coal-measures; and
others in the older Devonian, and even in the Silurian rocks. They
are associated frequently with other Ostracodous valves, such as
Beyrichia, Leperditia, Cytheride, and Cypride of various alliances.
In this part of the Monograph we find 183 Cypridine (directly related
to the existing Cypridina); 7 Cypridinelle, 9 Cypridellinee, 6 Cypri-
delle, and 2 Sulcune, which are genera arranged artificially to
receive several forms of carapace varying by gradational differences
from the valves of the known Cypridina ; 2 Cyprelle ; 1 Bradycinetus ;
1 Philomedes ; and 2 Rhombine, of which much the same may be said
as of the foregoing ; also 4 Entomoconchi, 1 Offa, and 3 Polycopes.
The definition of the true Cypridine,—the true allocation of the

* Published by the Paleeontographical Society, vol. xxviii.

PROGRESS OF MICROSCOPICAL SCIENCE. 305

several species placed by De Koninck under Cyprella, Cypridella, and
Cypridina,—and a more exact interpretation of M‘Coy’s Entomoconchus,
are (besides many new species) the chief novelties of this memoir,
which is illustrated by five plates (by George West) very full of
excellent figures of these small fossils.”

Reproduction of Ulothrix zonata.—In a series of most valuable
abstracts of German botanical papers that Mr. 8. Le M. Moore is
giving in the ‘ Journal of Botany’ (May), appears the following, which
is taken from a paper by Dr. Arnold Dodel in ‘ Pringsheim’s Jahr-
bucher fiir Wissenschaft. Botanik’ (vol. x. p.417):—Ulothrix zonata has
spores of two kinds—viz. 4-ciliated macrozoospores produced either
singly or two together in the mother-cell, and 2-ciliated microzoo-
spores arising several together in each mother-cell. Sometimes the
two spore-forms are found in neighbouring cells of a thread, but they
usually have distinct periods of activity, autumn and winter being
favourable to the formation of macrozoospores, and spring and summer
to that of microzoospores. The latter copulate and form resting zygo-
zoospores, a fact which sets Areschoug’s position beyond cavil; but
the strangest thing of all is that those individuals which fail to
copulate are like the macrozoospores in having the power of imme-
diate asexual reproduction. This most remarkable observation, which
its discoverer regards as furnishing a transition state between sexual
and asexual generation, comes to some extent to the timely support of
the Strassburg school, who deny that the fact of germination is suffi-
cient proof of the asexuality of spermatia. Several figures are given
showing polymorphism of the threads and of the zoospores; between
the two forms of the latter there are all kinds of transition, the only
absolute distinction being based on the number of cilia. Further, it
has long been known that microzoospores sometimes germinate while
still in the mother-cell, and Dr. Dodel has seen some of them dege-
nerate in this position without budding. Dr. Dodel agrees with
Pringsheim that copulation of microzoospores is the morphological
type of sexual reproduction. As for the zygozoospore, which, germi-
nating after its period of rest, produces, not a thread of cells but a
variable number of zoospores from which the threads arise, it is
regarded as an independent new sexual generation, so that we have in
Ulothriz true alternation of generation. Dr. Dodel points out the
affinity of Ulothrichee to Volvocinee and Hydrodictyee, but he is too
prudent to dogmatize on the subject of classification. He holds,
however, that the facts he has discovered afford strong support to the
theory of evolution, as they show how (morphologically, of course) an
asexual cell may become endowed with sexual properties.

MicroscopicAL Contents oF ForEIGN JOURNALS.

Archiv fiir Mikroskopische Anatomie, 13 Band, 4 Heft (continued
from last number of ‘M. M. J.’)—On the Cell-formation which
occurs in the Connective Tissue of Muscles, by Walther Flemming,
This is a paper illustrated by three very good plates. It treats

306 NOTES AND MEMORANDA.

exhaustively of the subject of the structure of the connective tissue.
The author deals principally with molluscan structures, giving those
of Mytillus edulis and Anodonta piscinalis very fully. He makes out
connective tissue to be a far more complex structure than it is gene-
rally believed to be, and his preparations, which are capitally drawn,
bear him out. The preparations have been mounted in various ways.
He has used, for example, alcohol, bichromate of potass, turpentine,
glycerine, and osmium. For injections he has used Prussian blue and
picro-carmine. The most important point he shows is that of the
relation of the so-called schleim-cells. The memoir covers fifty pages.
—There is also a short paper, by Herr Fr. Meyer, on preservative
fluids for microscopic objects.

Reichert and Du Bois-Reymond’s Archiv (January).—Carl Sachs
describes and figures the terminations of nerve-fibres in certain ten-
dons.—F. Boll’s article on the Savian vesicles found in the torpedo
about the nasal orifices and between the external edges of the elec-
trical organs and the limb-cartilages, is very interesting, because he
demonstrates the existence in their epithelium of spindle-shaped cells
corresponding in character to those so commonly found in special
sense organs.

The Zeitschrift fiir Wissenschaftliche Zoologie, vol. xxvi. part 2.—In
this Herr Repiachoff continues his contributions on the Chilostomous
Bryozoa, giving many interesting particulars about the development
of the amphiblastic ovum of Lepralia and Tendra.—Herr Ludwig Graff
describes the anatomy of the Sipunculoid Chetoderma nitidulum.—
Dr. Hubert Ludwig writes on the interesting Gastrotrichous Rotifers,
established as a separate order by Metschnikoff.

NOTES AND MEMORANDA.

Is Vision with the Microscope Finite or Unlimited 2—A paper on
this subject appears in the ‘ Boston Journal of Chemistry, and is
evidently written by one who is accustomed to microscopical re-
search. We give it in full as follows:—The question of the limits
of visibility is an eminently practical one, of great interest to all
microscopists and physicists. On this question Mr. Sorby says: “ The
highest powers of our best modern microscopes, he {Helmholtz ?]
assumes, will enable us to see objects an eighty-thousandth part of an
inch in diameter.” This sentence hardly represents Mr. Sorby’s posi-
tion. After referring to Helmholtz’s principles of interference fringes,
or diffraction, he says, “ It appears to me that we cannot do better than
to adopt these principles in forming some conclusion as to the size of
the smallest object that could be seen with a theoretically perfect
microscope. Looked at from this point of view alone, with a dry
lens this could not be less than one 80,000th of an inch.” This

NOTES AND MEMORANDA. 307

passage, it will be at once seen, is limited to the “dry lens,” and
while he says the “smallest object,” the context shows that he means
the separation of lines, and nota single object, for he at once goes on to
show that closer lines may be separated by the use of blue light and
immersion objectives, and also says, “ The size of the smallest bright
point that can be seen depends on entirely different considerations,
and might be considerably less.” All these speculations of Sorby
and Helmholtz (and Abbe may be included) are based on theoretically
perfect microscopes. (In this case the ‘ microscope” means the
objective, the all-important part of the instrument.) Now who ever
saw a “theoretically perfect” microscope? Who can ascertain, that
one is theoretically perfect? How can it be ascertained that one is
perfect? The only possible way of measuring the approximation
towards perfection is by the performance. So long as the per-
formance of the best microscopes falls short of what a theory says is
possible, the theory may be accepted as correct; but when the micro-
scope has done more than theory says is possible, theory must be in
fault. For years microscopes have been made, and are in use, that
do more than Helmholtz’s theory will allow. The difficulty with
Helmholtz and Abbe is that they had not seen and experimented, in
1872, 1875, and 1874, with all the microscopes that had been made
at that time, but only with such German instruments as came in their
way; and that made their theories to agree with the performance of
those instruments. That the theories are wrong is proved by the fact
that Nobert’s lines, finer than 112,000 to the English inch, have been
seen repeatedly by numerous observers, whereas Helmholtz fixes the
theoretical limit at 110,000. On the other hand, as yet no lines so
fine as 114,000 to the inch have been seen. Nobert has ruled lines
that he claims are 224,000 to the inch. Until something finer than
112,000 is actually seen, it must be an open question whether the
failure is the fault of the microscope or of the ruling. Nobert him-
self has not seen his own finer lines, and always pronounced it im-
possible to see any finer than 80,000 to the inch, until he saw 95,000
to the inch with a Tolles’ immersion lens. The writer saw 90,000 to
the inch with a dry lens more than ten years ago. As to the size of
a single object which may be seen, there is but little known. The
limit is undoubtedly in the perfection, or rather want of perfection,
in the microscope. The best experiments in this direction have been
made by Mr. W. A. Rogers, of the Cambridge observatory. Various
writers have assigned different values to the angle at which an object
can be seen, varying from 6” to 120”. This is, of course, a physio-
logical matter. Mr. Rogers says, “ Even the smallest value named is
much too large. I will at any time undertake to rule a single line
one 30,000th of an inch in breadth, which can be seen the distance
of seven inches from the eye. This corresponds to an angle of about
1”. Comparing minute particles of matter which can be seen under
a Tolles’ ,1,th objective with those that can be measured, in the
way indicated above, there is every reason to suppose that the limit
of visibility falls beyond one 400,000th of an inch. But that light
is of ‘too coarse a nature’ to enable us to see particles of matter as

308 CORRESPONDENCE,

small as one 200,000th of an inch is a conclusion which can be re-
futed without the slightest difficulty.” A few years ago Mr. Huxley
said in substance, at a meeting of the London Microscopical Society,
that if the opticians could not supply microscopes that would enable
one to see spaces between objects one 100,000th of an inch apart,
naturalists were at the end in that direction of their work. It was
replied that American and London opticians had already supplied
instruments that had separated lines but one 224,000th of an inch
apart.

CORRESPONDENCE.

THe LATE Proressor Cu. G. Enrenpera’s RESEARCHES ON THE
Recent AND Foss, FoRAMINIFERA.

To the Editor of the ‘ Monthly Microscopical Journal.’

Srr,—The following observations on Dr. Ehrenberg’s researches
may not be uninteresting to your readers.*

Amongst the most enthusiastic observers and voluminous writers
on microscopic organisms, Dr. Ehrenberg stands pre-eminent. By
the end of the year 1838 he had reduced to order the multitudinous
specimens of recent and fossil Microphytes and Microzoa which he
had either collected, with Dr. Hemprich, in the East (Egypt, Dongola,
Syria, Arabia, and Abyssinia), or had received from numerous corre-
spondents.

In the ‘Transactions of the Berlin Academy of Sciences’ for 1831,
1832, and 1838, Dr. Ehrenberg published the results of the researches
made on Corals and associated animals by Dr. Hemprich and himself
in 1823-25 among the islands and coral-banks, and along the coasts
of the Red Sea. In this memoir, after reviewing the systems of
classification adopted by his predecessors, he separated the Coral
animals into Anthozoa (flower-animals) and Bryozoa (moss-animals) ;
and the former he divided into Zoocorallia (comprising Polyactinia,
Octactinia, and Oligactinia), and the Phytocorallia (comprising Poly-
actinia, Dodecactinia, Octactinia, and Oligactinia). Altogether he
enumerated 386 living species, of which 110 he had himself observed
in the Red Sea. The range of Corals and their occurrence in the
fossil were also noticed.

The classification here alluded to has been superseded by others
based on a still more intimate knowledge of the structure and phy-
siology of the Celenterate groups—Hydrozoa and Actinozoa; whilst
the classification of his “ Bryozoa” (Polythalamia,t Gymnocore,
Thallopoda, and Scleropodia), mingling Foraminifera and Polyzoa,

* These remarks are based on some critical notes on Ehrenberg’s species of
Foraminifera in the ‘Annals and Mag. Nat. Hist.’ Ser. 4, vols. ix. and x.

+ Ebrenberg’s “ Polythalamia” (divided into Monosomatia and Polysomatia)
consist of Forumimifera with some Polyzoa.

CORRESPONDENCE. 309

could not greatly assist zoological investigation. Some interesting
conclusions, however, were arrived at, valuable and true in the main,—
namely, that the same kinds of Foraminifera occur both recent and
fossil ; that, nevertheless, each set of strata has more or less decidedly
its own special group of Microzoa ; and that Chalk in particular, and
probably most limestones and calcareous marls, are largely composed
of Foraminifera (Polythalamia, Ehrenb.). Thus these minute or-
ganisms, with Coccoliths (Morpholites, Ehrenb., in part), appear to be
the main constituents of the White Chalk. Although even recent forms
of Microzoa are found in the Chalk, Ehrenberg warns us that these
lowly creatures only go to prove that this, like many other calcareous
rocks, is a “ Halibiolith,’ or marine deposit of organic origin; and
not that the Cretaceous and Recent periods have been closely linked
by identity and continuity of high grades of life.*

Amplifying with his own increased knowledge the already published
observations on the persistence of low orders of life, Dr. Ehrenberg,
having studied some living Foraminifera of the North Sea, at Cuxhaven,
contributed in 1839 an interesting memoir to the Berlin Academy,
figuring two living species (Polystomella striato-punctata and Nonionina
umbilicata) with great exactness, as well as some obscure forms, which
he found in both the living and the fossil state} This memoir is
given in English, with the original plates, in Taylor’s ‘Scientific
Memoirs,’ vol. iii., art. xiii.

In 1843 several highly magnified figures of minute recent Forami-
nifera from America were treated of and illustrated by Ehrenberg in
the Berlin Academy Transactions for 1841.

Dr. Ehrenberg’s memoir “ On the muddy deposits at the mouths and
deltas of various rivers in Northern Europe, and the Animalcules found
in these deposits” { was noticed at large in the ‘ Quart. Journ. Geol.
Soe.’ vol. i. p. 251, &c., as illustrative of the influence of microscopic
life (chiefly Diatomacez) on recent and fossil stratified accumulations.
Few can now recollect the astonishment with which geologists received
in 1836 the assertion that large masses of rock, and even whole strata,
are composed of the remains of microscopic animals and plants ;§ but
this assertion has been confirmed and extended, largely by Ehrenberg’s
further labours, and we now recognize many “ Halibiolithic” deposits
and Diatomaceous earths.

In the ‘ Abhandl. Berlin Akad.’ for 1847, many extremely minute
Foraminifera, occurring in wind-dust on different occasions, in several
parts of Europe, are described and figured. They form part of the
curious gatherings of invisible things that wind-storms make and dis-
perse in their whirlings over the surface of the earth,—sweeping the
sea-shore, sand-bank, and dry river-bed, the volcano, the desert, and

* ¢ Quart. Journ. Geol. Soc.’ vol. xxviii. pp. 122-124.

+ The late Mr. Thomas Weaver, F.R.S., in the ‘ Annals and Mag. Nat. Hist.’
1841, and in the ‘ Philos. Mag.’ of the same year, gave a full abstract of two of
Ehrenberg’s memoirs (read in 1838 and 1840) above mentioned, together with an
appendix touching the researches of Alcide d’Orbigny on the Foraminifera of the
Chalk of Paris.

t From the ‘ Abhandl. k. preuss. Akad. Wissenschaft. Berlin’ for 1843.

§ ‘Proceed. Geol. Soc.’ vol. iii. p. 62.

310 CORRESPONDENCE.

the ploughed field, for organic and inorganic particles, and winnowing
its dusty harvest over distant and far different areas. These tiny
Foraminiferal waifs, potent witnesses of the path and doings of the
wind-storm, being figured by transmitted light only, like those of 1841,
teach little as to genera and species.

In these memoirs, and in shorter collateral notices in the ‘ Monats-
berichte’ of the Berlin Academy of Sciences (namely, for 1838, 1840,
1844, 1858, &e.), Ehrenberg treated of numerous Diatomacee (“ Poly-
gastrica”’*), Polycystina,} Foraminifera (“ Polythalamia”), Spongoliths,
Geoliths, Phytoliths, and other microscopic organisms, which he had
found, either recent (especially in the Red Sea, the Mediterranean, and
the North Sea), or fossil in numerous deposits of various ages, such as the
Mountain-Limestone, Oolite, Chalk, Tertiary, and Post-Tertiary strata.
Some few of the recent and fossil species referred to in these memoirs
were figured by him in the ‘ Abhandlungen’ for 1838 and 1839 ; but it
was not until 1854 that Ehrenberg was enabled to fulfil his earnest and
laudable desire to give to the world faithful and manifold portraits of
the well-prepared and almost innumerable microscopic objects on which
his published opinions had been founded. In 1854 the crowning of
his favourite labour was accomplished in the publication of the ‘Mikro-
geologie, with the recognition and aid of the State. In this grand
work, beside multitudes of fossil Diatomacee, Polycystina, Spongoliths,
&e., the long-looked-for Foraminifera were depicted, from his own
drawings, with the best artistic skill, with loving care and right royal
liberality. There are 4000 figures, in great part coloured, and all,
except plate 40, magnified at least 300 times linear.

With regard to the zoological determinations of Foraminifera,
there is a great discordance between Ehrenberg and other Rhizo-
podists; nevertheless, taking a broad view of the results of his labori-
ous, if not accurately discriminative, work among the fossil and recent
Foraminifera, we may fully acknowledge his having shown that several
living species are also to be found fossil in Tertiary and Cretaceous
deposits. Throughout the ‘Mikrogeologie’ there appear numerous
persistent forms, belonging to the Cretaceous, Tertiary, and Recent
periods, These his experienced eye readily detected; and in many
instances his lists show their relationship ; but, for some occult reason,
he failed generally to characterize them by description and nomencla-
ture, though often grouped naturally on his plates. As with his
classification of the Foraminifera among his “ Bryozoa” (1839), so
with his ‘Mikrogeologie’ (1854), he failed to seize the clue to the
right understanding and disentanglement of these many-featured
Rhizopods. Ehrenberg’s truthful plates, however, supply the rhizo-
podist with a storehouse of beautifully prepared specimens, mostly
seen by transmitted light; and from these, for by far the most part,
good and useful conclusions can be drawn, as from fresh specimens,
except that, being viewed only as transparent objects, with but little

* The “Polygastrica” of Ehrenberg, or “Infusoria,” comprise Jnfusoria,
Diatomacee, Desmidiacee, and some Gromide.

t+ Ebrenberg’s Polyeystina comprehend the Polycystina, Acanthometrina, and
Thalassicollida of later authors, by whom the whole group is termed Radiolaria.

CORRESPONDENCE. 311

perspective, and rarely with both faces of the shell, they too often fail
to satisfy the student, though the artistic labour bestowed on them has
been exact and conscientious.

( To be continued.)
I remain, Sir, yours, &c.,
T. Rupgrr Jones.

Mr. Arcuer’s Genus HyaLospHENta.
To the Editor of the ‘ Monthly Microscopical Journal,
READING, May 5, 1877.

Sir,—Mr. Archer, in his “ Résumé of Recent Contributions to our
Knowledge of Fresh-water Rhizopoda” in the current number of the
‘ Quarterly Microscopical Journal,’ refers “a lobose, monothalamian
sarcodine” to the genus Hyalosphenia, instituted, with questionable
propriety, by Stein, and accepted by Mr. Archer, though with obvious
hesitation.

Permit me to say that the so-called Hyalosphenia lata recently
detected by E. Schultze is neither good as a genus nor new as a species,
having been briefly described and correctly figured in your own Journal
so far back as December 1870, under the name of Difflugia ligata by

Yours truly,

J. G. Tate.

Lorp 8. G. Ossorne’s Exursrror.
To the Editor of the ‘ Monthly Microscopical Journal.’

SIDMOUTH.

Sir,—As I find that my former letter to you on the subject of
an instrument to facilitate the exhibition of the Diatomacex, and other
objects, requiring very oblique light when examined with high powers,
has attracted the attention of some good observers, will you kindly
permit me to offer a few more words on the subject, as I am anxious
to prevent any disappointment to those who may try it.

I find, and have informed Mr. Curteis, that all the apertures
necessary, may be with ease cut on one disk. If a line is drawn
through the centre of a disk, crossed by another at right angles, a
good workman will with ease cut four apertures, one on each of these
lines. They should be one-tenth of an inch from the point at which
the lines intersect. If so cut, when the disk is revolved, each aperture
will in turn come to the same position as regards the slide on the
stage; they will not in any way interfere with each other. This
plan saves a great deal of trouble, and enables the observer to try the
effect of each aperture on any object, with the greatest ease, and no
disturbance of any part of the instrument.

I always now use four apertures so cut—a fine slit, and three
triangles punched in different positions as regards the centre of the
disk; in the case of each, taking care that their illuminated edge
should be the one-tenth of an inch from the centre.

It much facilitates the use of the Exhibitor, if, before this disk is

313 CORRESPONDENCE.

put in over the small drum lens, the mirror is worked until it gives a
reflexion of the lamp—strong on the edge of its diameter farthest from
the lamp.

I use as lamp, and most strongly recommend the following simple
plan. On the sliding tube which carries the shade of an Acland
lamp, I slide a tin shade blackened, covering the whole chimney. In
this shade is a circular aperture opposite the flame, against which I
fix an ordinary condensing lens; a tin cap slips over this with an
aperture } inch in diameter, at the base of a cone projecting 2? inches ;
at the mouth 1} inch in diameter. I have two small cones to pass
into this, as diaphragms;-one with small circular aperture, the
other a slit the size of the flame. I find it best to blacken all parts
of the tinwork. I have given Mr. Curteis a drawing of the arrange-
ment.

I have, since I wrote to you, tested the power of the instrument in
every possible way; it has never failed me. I can get diatoms bril-
liantly illuminated on perfect black ground, and on any shade up to
a soft grey light. With the 4 inch of Ross, the Type-Platten is a
most beautiful study. With the highest objectives, I, with ease, get
all the definition of which they are capable, with very little trouble.

Let me add, I have arrived at the conclusion there are some—
daily I read of more—individuals whose eyes must be constructed
after a fashion very different from my own, and that of anyone I ever
met with. Their crystalline lenses must have been by nature gifted
with a power of correction which counteracts any and every short-
coming in any object-glass. To them “the screw-collar” is a super-
fluity ; they have a special visual power which adapts itself to the
thickness of any covering glass. They have a peculiar power of
penetration by their own eye-piece which supplements in the most
extraordinary way the eye-pieces of the best opticians; to resolve a
Pellucida into hemispheres with a + inch of Ross is an easy thing!

IT must confess I envy these most highly gifted men. I have
worked hard at Diatomacese with the best powers of the best makers.
I have used good, expensive sub-stage illumination, as well as some
months’ work with my own contrivance, I can make nothing of
Pellucida beyond the beauty of its outline; I can with ease make out
the longitudinal and transverse lines of the larger Rhomboides, with
their intersection ; the small Rhomboides with some care gives me one
set of lines well, the other faintly ; Crassinervis beats me.

The best tests of good magnifying power with penetration for high
powers, are, to my mind, good specimens of Versicolor and A. trilin-
gulatus ; an object-glass which shows the full structure of these beautiful
objects, I hold to be next to perfect, especially when seen on a black
background. I shall be most glad if any of my brother microscopists
are more successful than I have been with the Exhibitor; I shall be
quite content if they meet with my own success. Nature has only
given me the ordinary eye, now old; younger men of gifted eyes,
may, for all I know, spot Pellucida with the Exhibitor; I shall hear
of it with satisfaction, yet with envy.

S. G. Osporne.

Gezis.-)

PROCEEDINGS OF SOCIETIES.

Royat Microscorican Society.

Kine’s CoLiece, May 2, 1877.
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.
The Secretary read the following letter, which had been received
from C. J. Lambert, Esq.

3, QurEN SrreeT Puace, Upper Tuames STReet,
Lonpon, April 24, 1877.

Sir,—My father, by his will, left a sum of 25,0001, which he
requested me to distribute among persons in his employ, and in gifts
to scientific societies, in such manner as I should think fit.

I have the pleasure to inform you that I propose appropriating
to you, out of the legacy, a sum of 500/., and I enclose a legacy receipt,
which I will thank you to sign and return to me, and I will then
forward you a cheque for the amount.

I remain, yours, &e.,
The Royal Microscopical Society, C. J. Lampert.

King’s College, Strand, W.C.

P.S.—I have been induced to appropriate this sum to your society
at the suggestion of one of your Fellows, Mr. John Badcock.

Co da

He also stated that the money had been received by their Treasurer,
and would be invested with the other property of the Society. He
had only further to propose a special vote of thanks to Mr. Lambert
for his munificent donation, and all would agree that their thanks
were also due to Mr. Badcock for his very useful intervention.

Votes of thanks were then put to the meeting, and carried by
acclamation.

The President said, that before proceeding to that for which they
were more particularly assembled, it would be well for him to say a
few words as to the origin of the series of lectures which they were
about to inaugurate. It was something like two years ago that the
Council of the Society resolved to institute a lecture, to be called
the Quekett lecture, in honour of the late Professor John Quekett,
and to be delivered from time to time by eminent microscopists;
and it was thought that in memory of these occasions it would be

“well to present to the lecturer the Quekett medal of the Society, for
which dies had been some time ago prepared, but which had not
hitherto been utilized. Various circumstances had intervened to pre-
vent this arrangement from being carried out; but at length they
were met together to hear the first Quekett lecture, which was to be

314 PROCEEDINGS OF SOCIETIES.

delivered to them that evening by Sir John Lubbock, on whom he
had great pleasure in calling.

Sir John Lubbock, Bart., M.P., F.RS., &c., who was received with
hearty applause, having expressed his sense of the honour conferred
on him by the Council in selecting him as the first Quekett lecturer,
proceeded to deliver his lecture “On some points in the Anatomy of
Ants.” The subject was well illustrated by a number of coloured
diagrams enlarged from microscopic sections and preparations, and
also by a series of beautifully executed drawings, which were placed
upon the table. The lecture will be printed in a future number.

The President was quite sure he should express the wish of every
one present in proposing a hearty vote of thanks to Sir John Lubbock
for his very interesting and instructive lecture. He had himself
listened to it with very great pleasure, and had no doubt that it had
been listened to with equal pleasure by all who were present. He
therefore proposed that they should all join in a vote of thanks for the
very able lecture which they had been privileged to hear.

Mr. Charles Brooke said that he also had been very much inter-
ested by the lecture, and greatly pleased with the very able manner
in which the anatomical structure of so minute an animal had been
described. He hoped that, as time went on, their learned lecturer
would be able still further to follow out his interesting subject, and
that they might hope to hear some more of the results of his inves-
tigations at a future date. He had very great pleasure in seconding
the vote of thanks to Sir John Lubbock.

The vote of thanks was then formally put to the meeting by the
President, and carried by acclamation.

The President said that he had now the pleasing duty to perform
of presenting the Quekett medal to the lecturer of that evening ; and,
addressing Sir John Lubbock, he expressed the very great pleasure
he had in presenting it to him in the name of the Council and of the
Fellows of the Society; and he could not help expressing also his
gratification at the opportunity thus afforded of doing honour to one
whom it was his privilege to regard both as a personal friend and as a
man of science.

Sir John Lubbock, in reply, assured the Council and the Fellows
that he felt very highly the honour conferred upon him in having
been requested to deliver this lecture. He should preserve the medal
with some degree of pride, and his family would preserve it as a
much-prized memorial of the proceedings of that evening; and he
would further say, that if anything could enhance its value in his esti-
mation, it would be the fact of his having received it from the
hands of his highly esteemed friend, the honoured President of their
Society.

Scientific Evening, April 3, 1877.

Exhibitors and Objects.

The President, H. C. Sorby, Esq.: Specimens showing the appli-
cation of the microscope to the determination of the index of refraction
of minerals. Remarkable characters of double refracting crystals.

PROCEEDINGS OF SOCIETIES. 315

Mr. J. W. Bailey: A folding microscope of new pattern.

Mr. Charles Baker: Lord G. 8. Osborne’s new diatom exhibitor.

Messrs. R. and J. Beck: Pleurosigma formosum upon a black
ground, with an achromatic eye-piece and patent achromatic con-
denser. Surirella gemma, with ;4, immersion with central stop and
patent condenser. New form of small microscope, with concentric
rotating stage, &c. Large portable microscope, with apparatus and
objectives complete.

Mr. Badcock: Megalotrocha albo-flavicans, &c.

Mr. John Browning: Absorption spectrum of bromine.

Mr. Charles Collins: Young hippocampi in four stages of develop-
ment.

Mr. Henry Crouch: Vegetable preparations double stained by
Dr. J. G. Hunt, of Philadelphia.

Mr. Encch: British trap-door spider, Atypus sulzeri, and spinnerets
of spider.

Mr. F. Fitch: Some very beautiful natural mounts of insects.

Mr. W. H. Gilburt: Asplemium bulbiferum, stained.

Mr. J. W. Goodinge: Pleurosigma angulatum, with ..

Dr. Gray: Rare diatoms from Santa Monica.

Mr. H. Hailes: Foraminifera, Spirillina vivipera var. Magaritifera
and Chilostomella ozizeki, &e.

Messrs. J. How and Co.: Dolerite intrusive in granite, trachytic
lava, and carboniferous limestone.

Mr. Thomas Howse: Peziza bicolor alive, and a section of the seed
of Oollomia grandiflora, showing delicate spiral threads which surround
the testa.

Dr. Lawson: Transverse section of human spinal cord, and Mi-
crosporon furfurans, a fungus that attacks the hair and skin.

Mr. W. G. Lettsom: Decomposed glass from Pompeii, mounted
by Sir David Brewster ; and a section of a Cornish mineral which
shows the bands due to Didymium.

Mr. R. T. Lewis: Rheea fibre under the microscope.

Mr. 8. J. McIntire: Eye of drone-fly.

Dr. Millar: Mylinsia Zittelli and M. Grayii, recent representations
of ventriculites.

Mr. Moginie: Living organisms.

Mr. 8. Norman: Spicula of Dendrospongia Sturii, human brain, and
precious opal.

Mr. Thomas Palmer: Micro-spectroscope and chemical changes
in substances.

Mr. W. W. Reeves: Young crinoid larve of Antedon on Bugula
flabellata from Torbay, lent by Major Lang.

Mr. Sigsworth: Section of hoof of the horse, showing the papille.

Mr. H. J. Slack: Section of fossil bone from Tilgate Forest, and
bulbs of Krupp’s silicate cotton.

Mr. Charles Stewart: Ovary of Dorocidaris papillata and Asper-
gillus glaucus.

Mr. Amos Topping: Injected drum of ear of frog ; ditto lung of
frog; and ova of ditto, in different stages of development.

VOL. XVII. Qa

316 PROCEEDINGS OF SOCIETIES.

Mr. F. H. Ward: Section of corn from toe, cornea of pig, and
Toenia grandis, stained.

Mr. Tuffen West sent some very beautiful drawings of the fol-
lowing objects.

List of Drawings.

Zoea, from Indian Ocean. Sarcopsylla, from fowl, Ceylon. Nyc-
teribia, vampyre bat. Nycteribia, details. Nycteribia, winged, from
Ceylon. Larva, Meloée. Acadus destructor. Acadus plumosus. <Aca-
dus from Hydrometra. Pachygnathasp. Acarus (new?) from moss.
Tetranychus from rosebush. Acarus from chaffinch. Acarus from
tropic bird. Listrophorus. Uropoda, miniature. Uropoda, mature.
Uropoda from bat. Hypopus from bee. Gamasus from fly, sheep,
ferncase, English snake. Pteroptus, Ceylonese bat. Argas foliaceus.
Argas Fischerii. Iaodes from tortoise, boa constrictor, Indian snake,
black bear, dog (I. Dugesii?), elk, ferret (I. ricinus), Indian goat-
herd, ox, South America (I. nigua), ‘unknown tortoise (rostrum).

Donations to the Library and Cabinet since April 4, 1877:

From

Nature. Weekly . 2s se: (es [issn piss. ce ss) ts eee peepee
FATheRenmM; eWeekly os. 6 scy de" ates as, Wes) eee Ditto.
Society of Arts Journal .. Society.
Report and Abstract of Proceedings of the Croydon Mieroscopi-

cal Society, 1876 ae Ditto.
Bulletin de la Société Botanique de France. 2 parts he Ditto.
Description of Selected Specimens sent to the International

Exhibition at a eo 1876, ib, the Medical mete

ment, U.S. Army .. . Department.
Smithsonian Report, 1875 Institution.

3 Slides prepared by Dr. Christopher J ohnstone, “of Baltimore Dr. Johnstone.

Watter W. REeEvEs,
Assist.-Secretary.

Mepicat MicroscopicaL Society.

Friday, March 16, 1877.—Henry Power, Esq., President, in the
chair.

Adeno-Sarcoma from Nose.—Mr. Crook exhibited a specimen of
this disease, removed on two occasions from the nose of a girl. The
growth itself presented glandular structure, small cell growth, and a
very large quantity of blood-vessels. He remarked upon its peculiar
situation, viz. on the floor of the nose, at its junction with the
septum.

Cochlea in Birds.—Dr. Urban Pritchard described and exhibited
specimens of the cochlea in birds, particularly that of the magpie.
He described it as a short straight tube, ending in a cul-de-sac, and
not spiral as in mammals; and when examined in transverse section
it presented on one side a quadrilateral cartilage and on the other
a triangular one (= the ligament of the cochlea in mammals).
Stretched between them were the Membrana tectoria, and M. Basi-
laris, enclosing the organ of Corti.

The auditory nerve ran up the length of the cochlea, adherent to
one wall; on section, the ganglion-cells could be seen in between the

PROCEEDINGS OF SOCIETIES. 317

nerve-bundles. The ultimate nerve-fibres were given off at right
angles, and piercing the quadrilateral cartilage en masse, ended in
fine fibres between the hair-cells in the organ of Corti.

The very end of the cul-de-sac was lined with “ vestibular cells,”
showing thus a marked difference between the birds’ and mammalian
cochlez.

On the triangular cartilage were columnar epithelial cells, going
on over the Membrana Basilaris, while on the quadrilateral cartilage
were hyaline cells, that filled the sulcus on its border, and corre-
sponded to the limbus in the mammalian cochlea. In answer to
several questions, Dr. Pritchard described his mode of preparing the
cochlea. Taking a small one, as a bird’s, he thus proceeds:

1. Place at once in methylated spirit.

2. In alcoholic solution of chromic acid (4rd per cent.) for five to
ten days.

3. In 1 per cent. solution of nitric acid, constantly agitating the
liquid, for one to four days.

4, Wash: transfer to gum and water for some hours.

5. In methylated spirit till wanted.

6. Imbed: cut section: stain: mount in glycerine.

April 20, 1877.—Henry Power, Esq., President, in the chair.

Double Staining with Indigo Carmine and Carmine.—Mr. Golding-
Bird read a paper upon this subject. He referred to an account of it
in the ‘ American Journal of the Medical Sciences’ for January 1877,
though it was originated by F. Merkel in Germany in 1874.

He described the dye as consisting of two fluids made separately,
but mixed before use; one was a boracic solution of carmine (carmine,
38s; borax, 3ij; distilled water, Ziv); the other, a similar solution of
indigo carmine (indigo carmine, 3ij; borax, 31); distilled water, Ziv).
Indigo carmine is the trade name for sulphindigotate of potassium,
and is the same dye as used by Chrzonszezewsky in his researches
upon the commencement of the portal duct.

The specimens to be stained, if hardened in chromic acid, must be
deprived of it by washing, and then immersed in the mixed dyes for a
quarter of an hour. After that they must be transferred to a saturated
solution of oxalic acid, both to “set” the blue colour as well as to
lighten the general tint, and then, having been washed in distilled
water, mounted in Canada balsam in the usual way.

The results obtained by this process, when successful, were both
instructive and beautiful, but unfortunately the same results did not
always follow, a great number of specimens showing often nothing
but a general purple tint resembling a successful logwood stain.

The author showed, however, several slides in which he had
obtained the double stain more or less perfectly. One specimen of
liver showed the portal canal remarkably well; the blood-disks in the
portal vein were of a brilliant apple-green; the hepatic artery, reddish
purple; the process of Glisson’s capsule, blue or blue purple ; and the
portal duct had its wall of the same colour but of a different tint, the
columnar cells lining it being just tinged a brownish purple with blue
nuclei. Another specimen of ossifying cartilage showed the various
component parts sharply picked out in blue, purple, red, and light green.

2 A

318 PROCEEDINGS OF SOCIETIES.

The cause that the author suggested for the failure of the dye on
some occasions was the imperfect action of the oxalic acid ; for while
it was necessary to fix the indigo blue, it effectually destroyed the
carmine by either precipitating it or turning it into a straw colour.

He did not consider the process as yet perfected, but hoped that by
finding some other reagent than oxalic acid, that would possess its
good without its deleterious properties, a more uniform and certain
result might in all cases be ensured.

From what he had seen, he thought that there was every promise
of obtaining important and instructive results from this new dye; as,
when successful in its action, it was a true physiological stain and not
merely a general one.

He also recommended, as a general dye, the use of the blue boracic
solution of indigo carmine by itself; it stained rapidly, was sufficiently
well fixed by the oxalic acid pr ocess, and was a colour most agreeable
to work with. He had employed it as an injection, but though it ran
well along the vessels, it was very difficult to fix in them, as it rapidly
transuded and stained the surrounding tissues.

Mr. Crook had tried the double dye, but not sufficiently extensively
to speak positively as to its action.

Mr. Needham, though he thought a double dye, in one fluid, most
valuable, had been disappointed in double dyes generally. Picro-
carmine was not constant in its action.

Mr. Ward spoke of double staining with two aniline dyes, especially
for vegetable substances. He had found the colour permanent if the
specimen were immersed in benzine after being in oil of cloves.

Fibroma of hard Palate—Mr. White showed a specimen of this
tumour under the microscope. He also exhibited a cast showing the
tumour in situ. It was about the size of a pea, and grew from the hard
palate just behind the incisor teeth. He especially remarked upon
its unusual situation.

Tumour of Conjunctiva (?small-celled sarcoma).—The President
related a case, illustrated by drawings and specimens, of a tumour of
the conjunctiva. It occurred in a patient over sixty years of age, and
first appeared at the edge of the cornea, which structure it involved
later on. Though removed several times, it still recurred, and even
appeared again on the stump of the optic nerve after enucleation of
the globe.

QuEKETT MicroscopicaL Cuus.

Ordinary Meeting, March 23, 1877.—Dr. John Matthews, F.R.MS.,
Vice-President, in the chair.

Three new members were elected, four gentlemen were proposed for
membership, and numerous donations were announced and acknow-
ledged.

“A letter relating to the “‘ Blyborough Tick” was read ; and in reply
to inquiries from the writer, Dr. M. C. Cooke mentioned that most of
the creatures of that family possessed six legs only in their early
stages, but afterwards had eight ; and he named several works to which
reference might be made for further information.

Mr. W. H. Gilburt read a paper “On the absence of Stomata from

PROCEEDINGS OF SOCIETIES. 319

certain Ferns,” and gave an account of his examination of many species
of the Filmy Ferns—Hymenophyllacee, Trichomanes, and Todea; in
each of which these organs were wanting. The specimens had been
prepared by both bleaching and double staining, and a selection from
them were exhibited in the room in illustration of the paper.

Mr. T. C. White called attention to a curious organ which he had
frequently observed to be attached to the third segment from the tail
of a species of marine Cyclops, and which until lately had been ex-
amined without success as to the discovery of its use or nature. Re-
cently, however, Mr. White had been fortunate in determining it to be
a spermatophore, and had seen under a }-inch objective spermatozoa in
active motion, which had just escaped from a crushed specimen under
examination.

The attention of the members was particularly requested to the
arrangements made for the soirée of the club to be held on April 13,
and the meeting closed with the usual conversazione.

Ordinary Meeting, April 27, 1877.— Henry Lee, Esq., F.LS.,
President, in the chair.

Four new members were elected, ten gentlemen were proposed for
membership, and a number of valuable additions to the library and
cabinet were announced.

Communications were read—from Mr. Bridgman respecting a new
tinted glass which he had been successful in obtaining, and concerning
which it was hoped that additional particulars would be furnished at
a future date; also from members of the Excursion Committee, giving
short and interesting reports of the field excursions of the club to
Barnes on March 24, and to Snaresbrook on April 7.

Mr. T. C. White read a paper on Botryllus, in which, after briefly
enumerating the characteristics of the Tunicates, he gave the results
of his personal observations on the life-history of specimens developed
in his marine aquarium, the chief point of interest being the discovery
of a method of progression which did not appear to have been previously
noticed. The subject was well illustrated by drawings.

Mr. Charles Stewart added some useful information as to the best
methods of preparation, preservation, and mounting these organisms,
and

The President expressed a hope that Mr. White would continue his
very useful investigations, and promised him such supplies of material
from the Brighton Aquarium as his influence could procure.

The proceedings terminated as usual with a conversazione, at which
a number of interesting objects were exhibited.

Microscoricant Section, Roya Socrety,* New Sourn WALEs.

The above Section, in conjunction with others of the Royal Society,
each having for its object some specific branch of scientific inquiry,
held its first meeting on June 28, 1876, and during the rest of the

* If the Secretary will send us brief records of the papers read we shall
gladly insert them, but we have not space for a general discussion of the subject
of societies in general, which he has sent us at present, and which we eannot
insert.

320 PROCEEDINGS OF SOCIETIES.

year regular monthly meetings have been held, with large attendances
of members. A large cabinet has been purchased, and many valuable
contributions of slides have already been received. A first-class
microscope stand, to be placed in the Society’s room, has been or-
dered, and members belonging to the Section will have the privilege
of using it for any special branch of investigation for which their
own means might prove inadequate. During the session the following
papers have been read :—On the Action of Alkali on Wood Fibres,
by Mr. G. D. Hirst; The Starch of the Macrozamin spiralis, Dr. Mil-
ford ; On Exostosis of the Human Tooth, Mr. H. Paterson ; Note ona
Species of Chelifer, Mr. G. D. Hirst; On two Species of Insectivorous
Plants indigenous to the Colony, Mr. J. N. C. Colyer; The Milky
Juice of the Climbing Fig, Mr. H. J. Brown.

San Francisco Microscopican Soctery.

The regular meeting of the San Franciseo Microscopical Society
was held January 4.

The Society will soon have in its cabinet a complete series of
Professor H. L. Smith’s diatom slides, including the five “centuries”
issued by him, which will be a valuable acquisition.

The feature of the evening was a lecture by Dr. Gustaf Hisen,
Professor of Zoology, University of Upsala, Sweden, one of the
Society’s corresponding members, who called attention to a collection
of worms of the family Enchytreide, order Oligocheta, sent to him by
the eminent Arctic explorer, Professor A. E. Nordenskiold, in Sweden.
The worms were collected during the last Swedish expedition to
Siberia and Nova Zembla, and especially from the neighbourhood of
the river Jenissej. Dr. Eisen exhibited some twenty plates of draw-
ings, containing about one hundred and fifty different figures of the
various organs of said worms, and illustrated his descriptions by
various microscopical slides. The principal points of interest were
the following:

The collection contained about eighteen species, or perhaps more,
as the whole of the material was not as yet worked up. Of those
species, none were previously known or elsewhere described. From
Germany three or four species of the same genus have been suffi-
ciently well described to be identified, but none of them have been
identified with any in the collection from Siberia.

In the course of his remarks, Dr. Eisen stated that the inner
organs of said worms differed very much in size and shape, and fur-
nished the only characteristics by which the species could be distin-
guished from each other, as no external characters of sufficient value
existed. One of the best characteristics is furnished by the size and
shape of the nervous system, and especially by the foremost part of
the supra-cesophagial ganglion or brain. By studying the organiza-
tion of the different species, one could guess at or even form an idea
of the development of the whole genus. For instance: the brain of
said worms must originally have consisted of only a slight swelling
of the ventral ganglia or nerves, of which the two parts had not as

PROCEEDINGS OF SOCIETIES. - 321

yet grown perfectly together or been differentiated to any higher
degree. In such a state of development was yet one of the exhibited
species called Enchytreus primevus. In fact, by looking at the
different species, a perfect series could be seen of the different states
of the development of said ganglion or brain. In Enchytreus
nasutus the differentiation was larger, as the two halves of the brain
here were wholly grown together, but still leaving some traces of
their former state by being concave both in front and behind. In
Enchytreus Stuxberguvi the differentiation was perfect, as the brain here
was convex in front. Said worm was also considered to be more
highly developed and organized than any of the other species of the
same genus and family. Accordingly, he separated the many species
into three tribes, of which the first or lowest had the brain concave
in front and behind ; the second had the brain concave behind, but
even in front; and again, the third or highest standing tribe had the
brain convex both in front and behind.

In the worms which were hermaphrodites were found organs of
generation of two kinds—male and female. The female organs con-
sisted of, first, ovaries containing eggs in different states of develop-
ment, and second, of a pair of receptacles for the spermatozoa,
peculiarly shaped, and varying in size and form in different species.
The ovaries were generally found in the twelfth segment, the recep-
tacles again always in the fourth segment of the worm counted from
the head or the mouth. The male organs consisted of first, testes
producing the spermatozoa, and second, of a pair of efferent ducts
through which the spermatozoa were carried to the outside of the body
and from there to the receptacles in the front part of the worm, where
they were stored up in large quantities for future use. The testes
were situated in or near the eleventh or twelfth segments, the efferent
duct was always found in the eleventh segment.

The minute anatomy and histology of said organs were shown
partly by drawings, partly by microscopical slides previously pre-
pared. The shape and development of the receptacles for the sper-
matozoa furnished good characters by which the different species
could be recognized.

The system of circulation was very simple, and consisted only of
a single ventral vessel uniting itself with a dorsal one in the front
part of the body. The blood was either red or white, the last the
most frequent. The lymphatic system was simpler yet, as here no
vessels at all occurred, the lympha floating free in the perivisceral
cavities of the body. The lymphatic fluid contained corpuscles re-
sembling the blood-corpuscles of the higher animals, and in each
species a different form of said corpuscles existed, giving good cha-
racters for the distinction of the species.

Dr. Hisen stated that he had also found several species of the
same genus Enchytreus in California, and called the attention of the
members of the Society to the value of even the smallest contribu-
tions to a collection of California Hnchytrei, which he was forming
and soon intended to work up. The said worms were frequently
found in moist earth, in flower-pots, under decayed seaweeds, &c.,

322 PROCEEDINGS OF SOCIETIES.

and were generally of a pale whitish colour, and in size seldom ex-
ceeding that of a common pin. The worms could best be preserved
in alcohol.

A meeting of the Society was held on Thursday evening, January
18, with President Ashburner in the chair,

Mr. J. R. Scupham presented a quantity of diatomaceous earth,
obtained by him from Fort Hill, Los Angelos, which was examined
somewhat hastily during the evening, and found to contain great
quantities of fragments of Coscinodiscus.

Mr. A. Burdick exhibited a slide motnted by him, showing a
minute portion of the thallus of a marine Alge from Monterey Bay,
to which was attached four species of diatoms. One of them, a Hyalo-
discus, would not reveal its beautiful markings till quite a high power
and proper illumination were brought to bear, when it surrendered,
and its fine and well-defined lines reminded the observer of the lathe
work on the back of a watch-case.

Colonel Kinne exhibited several slides from his box of duplicates,
one of antelope hair in balsam, showing the peculiar cellular structure
of the investing membrane and enlarged medullary portion, which,
though not new, attracted considerable attention.

The annual meeting of the San Francisco Microscopical Society
was held on Thursday evening, February 1, President Ashburner in
the chair.

As the only business of the evening was properly that pertaining
to reports from retiring officers and the election of officers for the
ensuing year, of course there was but little of scientific interest aside
from that gathered in the report of the President, which was of con-
siderable length, and furnished a very full and intelligent abstract of
the doings of the Society for the past twelve months.

Dr. A. M. Edwards was called upon, and, after some remarks of
general interest, he spoke of the scourge now visiting our city in the
shape of diphtheria, and after some extended remarks, which interested
all present, particularly Doctors Mouser, Whitney and Burgess, he
alluded to the great satisfaction with which he had treated many cases
in the East, with a solution of salicylic acid, applied in the shape of a
spray. He exhibited a series of drawings from the microscope, which
faithfully portrayed fungoid organisms, illustrative of diphtheric
growth. _ The salicylic acid invariably caused the disappearance of
fungal matter, and ultimately the disease was checked.

Mr. J. P. Moore, in this connection, spoke of the use, by himself,
of the same acid as a remedy for poison oak, and though he had here-
tofore been tortured by the poison on many occasions, by the use of
salicylic acid he now could cure the disease without trouble, while,
applied as a preventive, he was able to pursue the agile agaric, even
under the protecting branches of the poisonous shrub itself, without
fear of the consequences.

( 323 )

INDEX TO VOLUME XVII.

A.

Asse’s, Professor, Experiments illus-
trating his Theory of Microscopic
Vision, Observations on. By J. W.
STEPHENSON, 82.

Acarite, a New. By M. A. L. Donna-
DIEU, 283.

Address of the President, H. C. Sorsy,
Esq., 113.

Agassiz, Mr. A., How the two Eyes of a
Flounder come to the same side, 150.

Air, Examination of the, 156.

Alga, a new Parasitic Green, 256.

Alge, the Development of, 152.

Amcebe, on certain. By Professor
Lewy, 89.

Amphitetras antediluviana,
locality for, 102.

Angle of Aperture, increase or diminu-
tion of, 263.

Arctic Expedition, the Microscopic
Zoology of, 43.

a new

B.

Bacillariz, the Siliceous-shelled, 301.

Bacteria of Denmark, 96.

Baer, the Death of Von, 48.

Bathybius come to life again! 149.

Berke ey, M. J., &c., on the giving of
new Specific Names, 41.

Blood-corpuscles of a young Trout, Ob-
servations on the Structure of the.
By W. H. Hammuonp, Esq., 282.

of Ovipara, Structure of the
Red, 296.

Blood-globules of different Races of
Man, 212.

Blood-vessels of Muscle under the Mi-
croscope, 298.

Bottle, a Form of Collecting, 101.

Bowerbank, the Death of Dr., 215.

Brachiopoda, the Structure of the, 303.

Brain of the Insane, Microscopic
Changes in the, 258.

Briost, Professor G., on Phytoptus
vitis, 181.

G., on the Action of Chlorophyll

in the Vine, 285.

C.

Cartilage, the Matrix of Articular.
By Mr. H. A. Reeves, 39.
Cell-division studied Microscopically,

Centropyxis, the Structure of. By
Professor Lerpy, 149.

Chlorophyll, on the Action of, in the
Vine. By G. Briost, 285.

Starch in Granules of, 295.

Cobra Poison, the Microscopical Active
Principle of the, 297.

Coniferz, the Pollen of the, 262.

Controversy, the Blood-stain, 100.

the Tyndall and Bastian, 158.

Corals, Fungi Parasitic on. By Dr.
Duncan, 44.

Corpuscles of the Cornea in the Process
of Inflammation, on the Changes of
the Fixed. By G. F, Dowpeswet.,
B.A., 288.

Correspondence :—

BRAMHALL, JOHN, 162.
Davis, Henry, 105.
Frirp, H. E., 103.
GuIMARAENS, A. DE Souza, 217.
InGPEN, Joun E., 50.
Jones, T. RuPert, 308.
Kirton, FREDERICK, 106.
OspornE, Lord §S. G., 311.
RicHaRpson, J. G., 265.
Ross AnD Company, 217.
TateM, J. G., 311.
Watticu, Dr., 218.

elena Ganglion-cells in the Heart
of, 97.

Crustacea, the Structure of the Optic
Baton in. By M. J. Cuarti, 92.

Cucumaria doliolum, the Embryology
of, 36.

324

D.

Dat, W. H., on the Extrusion of the
Seminal Products in Limpets, 194.
DautwceEr, the Rey. W. H., on Frus-
tulia Saxonica and Navicula rhom-

boides as Test-objects, 1.

Additional Note on the
Identity of Frustulia Saxonica and
Navicula rhomboides, &c., 173.

Diamonds, Specks in the Cape, 43.

Diatomacee: on the Relation between
the Development, Reproduction, and
Markings of. By G. C. WALLIcH,
M.D., 61.

—— Typical Specimens of the, 100+

Diatom Earth of Richmond, US.A.,,
294.

Diatoms, some of the ‘Challenger’s,’ 158.

Cleaning with Glycerine, 161.

Dicotyledonous Root, Eriksson on the,
97.

Dicyema, Recent
Kolliker’s, 250.
Dionzea muscipula, the Structure and

Movements of, 42, 155.

Researches on

Distoma sinense, the Structure of, 256.

Donnanviev, M. A. L., ona New Acarite,
283.

DowpbeEswELL, G. F., on the Changes of
the Fixed Corpuscles of the Cornea
in the Process of Inflammation, 288.

E.

Echini, Researches on the, 42.

Echinoids, the Structure of the, 208.

Embryo, the Early Development of the
Mammalian. By Mr. E. A. ScHAFER,
32.

Empusa muse, Mr. T. C. WHITE on,
253.

Entomostraca, British Fossil Bivalved,
304.

Eosin: a New Staining Fluid, 161.

Epithelioma, a Novel Form of, 150.

Errata in the President’s Address, 249.

Exhibitor, The: a Novel Apparatus for
Showing Diatoms, &e. By the Hon.
and Rey. Lord 8. G. OsBorne, B.A.,
179, 311.

F.

Filaria heematica, Researches on, 157.

Flounder, How the two Eyes of, come
to the same side. By Mr. A. AassizZ,
150.

Focus of a Microscope, a Mode of alter-
ing the, without altering the Position
of either the Objective or the Object.
By M. Govt, 205.

INDEX.

Foraminifera, Carboniferous and Per-
mian, 303.

— the late Professor Ehrenberg’s
Researches on the Recent and Fossil.
By T. Rurert Jones, 308.

Forbes, the Death of David, F.R.S., 48.
Foreign Journals, the Microscopical
Contents of, 47, 98, 159, 214, 305. °
Fossil Earth of Richmond, U.S.A,

100.

Frustulia Saxonica, &c., 1, 173.

Fungi on the Bones of a Whale, 43.

Parasitic on Corals. By Dr.
Duncan, 44.

——— Reproduction in the Ascomycetes.
By M. Cornt, 295.

Fungus, Circulation in a, 255.

G.

Gems, Notes on “Inclusions” in. By
Isaac Lea, LL.D., 198.

GiarD, M. A., on the Modifications
which the Egg of the (Hooded-
eyed) Medusa undergoes before
Fecundation, 247.

Giieurt, Mr. W. H., on Volvox glo-
bator and Spheerosira volyox, 210.
Goopsir’s Arguments on the Develop-
ment of the Teeth of certain Rumi-

nants, 291.

Govi, M., a Mode of altering the
Focus of a Microscope without
altering the Position of either the
Objective or the Object, 205.

5.

Hair, Microscopical Researches on the
Growth and Change of the, 153.

Hammonp, W. H., Esq., Observations
on the Structure of the Blood-cor-
puscles of the young Trout, 282.

Heart in Chicken, Development of the,
157.

Hennecuy, M., on the different Sex-
uality of Volvox globator and VY.
minor, 35.

Heterotrichus inequarmatus, 283.

Hospital Walls, Microscopic Examina-
tion of, 153.

Hyalosphenia lata. By J. G. TaTem,
311.

I.

Illuminator, the, Van der Weyde’s
Oblique, 49.

Incubator, a Stage. By H. A. Rerves, 8.

Ttacolumite, the Structure of, 254.

INDEX.

K,

Kallispongia, a curious new Sponge,
251.

L.

Lavas, on the Lower Silurian, of Eycott
Hill, Cumberland. By J. Cuirron
Warp, 239.

Lea, Isaac, LL.D., Notes on “ Inclu-
sions” in Gems, 198.

Lerpy, Professor, Observations on Rhi-
zopods, 32, 259.

on Certain Ameoebe, 89.

— — on the Structure of Centro-
pyxis, 149.

Lichens and Fungi, the Formation of
Spores in, 211.

Limpets, on the Extrusion of the
Seminal Products in. By W. H.
Dat, 194.

Liver, the Lymphaties of the, 152.

Lymphatics of the Joints, 295.

M.

Magelona, the Circulatory System in,
258.

Marsh Poison of the Campagna, Micro-
scopic Investigation of the, 91.

Medullary Nerve Sheath, Tubular
Degeneration of the, 210.

Medusa, the Modifications which the
Egg of the (Hooded-eyed) undergoes
before Fecundation. By M. A. Grarp,
247.

Meteorites, the Structure and Origin of,
293.

Microscope, American Work with the, 38.

Professors Helmholtz and Abbe
on the Optical Powers of the. By
H. E. Fripp, 103.

— ls Vision with it Finite or Un-
limited ? 306.

Microscopic Vision, 160.

Microscopy at the American Exhibi-
tion, By R. H. Warp, M.D., 25.

Microtome, a New, 216.

Mr. Lewis’ Freezing, 300.

Monads, the ambiguous Position of
the, 97.

Mr. Dallinger’s Lecture on, at the
Royal Institution, 293.

Moriey, Epwarp W., Measurements
of Rulings on Glass, 137.

Mosses, Experimental Observations on,
209.

Moths, the Anatomy of, 40.

Muscular Fibres, the Examination
of, 39.

Mushroom, the Structure of the
Common. By Mr, Worruineron

Smivu, 36.

325

N

Navicula crassinervis, N. rhomboides,
and Frustulia Saxonica, as Test-
objects. By Rev. W. H. Dat-
LINGER, 1.

— Additional Note on the
Identity of. By Rev. W. H. Dat-
LINGER, 173.

Nerves, the Relation between Activity
of, and the Size of their Sheath, 44.

New Books, wirn SHort Norices :—
The Fungus Disease of India: a

Report of Observations, 31.
How to choose a Microscope, 89.
The Microscope and its Applica-
tion, 144.

O.

Objectives, Mr. Spencer’s, 99, 216, 262.

Opal, the Structure of Precious, 45.

Remarks on the Structure of
Precious, 296.

OspornE, Lord S. G., B.A., the Ex-
hibitor: a Novel Apparatus for
showing Diatoms, &c., 179, 311.

Oscillatoria and Bacteria, 208.

Oysters, the Sporules of Seaweeds the
cause of Colour in, 40.

P;

Packarp, Mr. A. §., jun., a Contest
as to Priority of Discovery, 93.

PALMER, Tuomas, B.Sec., on the
various Changes caused on the
Spectrum by different Vegetable
Colouring Matters, 225,

Panceri, Death of Professor, 264.

Phallus fcetidus, 45.

Phytoptus of the Vine, on the. By
Professor G. Brrost, 181.

Plants, the Embryonic Membranes in,
154.

Pollen, Notes on.
G. Suita, 9.
Priority of Discovery, a Contest as to.

By Mr. A. 8. Packarn, jun., 93.
PROCEEDINGS OF SucIETIES :—
Dunkirk (N.Y.) Microscopical So-
ciety, 55.
Liverpool Microscopical Society, 54,
171, 223.
Medical Microscopical Society, 109,
169, 222, 316.
Quekett Microscopical Club, 111,
318.
Royal Microscopical Society, 51, 107,
162, 219, 265, 268, 313, 314.
Royal Society, New South Wales,
319.
San Francisco Microscopical Society,
Of, LES M7 320:
Pyenidia, the Origin ef, 210,

By Worruineton

326

R

Red Clays of the Ocean-bottom, Mr.
Sorsy on the, 252.

Reeves, H. A., on a Stage Incubator, 8.

Reflex Illuminator, Dr. J. E. Smrrx on
Wenham’s, 160.

Renarp, Rey. A., on the Mineralogical
Composition and the Microscopical
Structure of the Belgian Whetstones,
269.

Rhizopods, Observations on.
fessor Lrrpy, 32, 259.

Rotifer vulgaris, Reproduction of, 301.

Rulings on Glass, Measurements of.
By E. W. Morey, 137.

8

Salpz, the Life-history of the, 98.

Scuirer, Mr. E. A., on the Early De-
velopment of the Mammalian Em-
bryo, 32.

Scleroderma verrucosum, the Develop-
ment of. By M. N. Soroxrng, 208.
Section Machine, the ‘ Science-Gossip,’

100.

Silicate Cotton, Microscopic Aspects of
Krupp’s. By H. J. Suack, F.GS.,
&e., 236.

Stack, H. J., F.G.8., Microscopic
Aspects of Krupp’s Silicate Cotton,
236.

Small-pox, Dr. Kurm’s Observations
on, 252.

SurrH, WortTuincton G., Notes on
Pollen, 9.

on the Structure of the
Common Mushroom, 36.

Sorsy, H. C., Esq., Anniversary Ad-
dress delivered before the Royal
Microscopical Society, Feb. 7, 1877,
113.

Specific Names, the giving of New, 41.

Spectrum, on the various Changes
caused on the, by different Vege-
table Colouring Matters. By THus.
PaumeEr, B.Sc., 225.

Speculum, Mr. Bridgman’s Mode of
Polishing a, 216.

Sphagnacez, Dr. Braithwaite’s Book
on, 97.

Sponges, the Position of the, 208.

Early Development of, 254.

Squilla mantis, the Sexual Organs of, 97.

STEPHENSON, J. W., Observations on
Professor Abbe’s Experiments illus-
trating his Theory of Microscopic
Vision, 82.

By Pro-_

INDEX.

1 ie

Tape-worm in a Cucumber (!), 302.

Tape-worms in Rabbits, 157.

Tatem, J. G., on Hyalosphenia, 311.

Teeth of certain Ruminants, Goonpsir’s
Arguments on the Development of
the, 291.

Tendon, how Nerves end in, 92.

Test-diatoms, how to .resolve, without
any special Apparatus, 102.

Thread-cells, gigantic, 158.

Tick, the Blyborough, 297.

Typhus, Microscopic Organisms in the
Blood of Patients suffering from, 91.

U.

Ulothrix zonata, the Reproduction of,
255, 305.

Urodelous Amphibia, Cranial Morpho-
logy in the, 153.

Af

Vaccination, the Microscopic Anatomy
of, 251.

Vision with the Microscope, is it Finite
or Unlimited? 306,

Volvyox globator and V. minor, the
different Sexuality of. By M. Hrn-
NEGUY, 35.

and Spheerosira volyox, are

they distinct Species? By Mr. W.

H. Gitsurt, 210.

W.

Wa uicu, G. C., M.D., on the Relation
between the Development, Repro-
duction, and Markings of the Diato-
maces, 61.

Warp, Dr. R. H., Microscopy at the
American Exhibition, 25.

J. Cuirron, on the Lower Silu-
rian Lavas of Bycott Hill, Cumber-
land, 239.

Whetstones, on the Mineralogical
Composition and the Microscopical
Structure of the Belgian. By Rev.
A. RENARD, 269.

Wuirte, THomas C., and W. W. Rrnves
on Empusa musce, 253.

Worm, a Nematoid, 157.

Worms, on the Eyes of, 156.

END OF VOLUME XVII.

LONDON: PRINTED BY WM. CLOWES AND SONS, STAMFORD STREET AND CHARING CROSS.

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