|

Le

Adex Agassiz.
Ribrary of the Museum

OF

COMPARATIVE ZOOLOGY,

AT HARVARD COLLEGE, CAMBRIDGE, MASS.

Founded by private subscription, (n 1S6L.

LPAI

Deposited by ALEX. AGASSIZ.

e No. le ve

>

_ ¢ —, _
Be PPO 459

4 -
aa .

oF rhe
re

a

iz 1
pan a
ae ae Mi :
we Ore war rh’ of

QUARTERLY JOURNAL

MICROSCOPICAL SCIENCE.

EDITED BY

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

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

VOLUME VII.

With Allustrations on Wood and Stone.

LONDON:
JOHN CHURCHILL, NEW BURLINGTON STREET.
1859.
nissan?

‘7 7
Sishiss Behe ctl ADIT00.

c \l

PEL eOOIhels ho

r rrr ey -

Wart = a vi

Pear Ar rpies wares re we oe vs 74 ae
pa sid Oa Br Oh a AE Wok if . f 3,4 stl e et oie)

oe

ORIGINAL COMMUNICATIONS.

8

On Apparatus for Drepcine at MODERATE DePTus in the
Derr Sea, and for Carturine Fioatine Ossects from
Surppoarp. By G. C. Watuicu, M.D.

Dvxine a recent voyage from India, the success attending
the use of certain appliances contrived by me for capturing
such marine objects as came in our way, induces me to offer
the subjoined account of them to the public. I may mention
that, although familiar with the ordinary form of towing net
and sounding apparatus, it struck me that much more might
be done by resorting to some simple form of casting net,
than is possible where the chapter of accidents is relied on
for bringing within the jaws of the towing net the objects
required, and by constructing some more portable sounding
apparatus, which would at the same time prove effective at
moderate depths, and bring up a much larger quantity of
material than is attainable under the ordinary sounding lead,
or the more complicated and cumbrous contrivance of Lieu-
tenant Maury and others. I would further premise that
whoever desires to make a collection of marine floating
molluses, tunicaries, ascidians, and the like, and also. the
minuter organisms which exist in all latitudes in the open
ocean, to a greater or lesser extent, will be grievously disap-
pointed if he imagines that the trailing net ‘used astern of. a
ship will suffice for the purpose. For, to be at all successful,
constant and unremitting watchfulness is, in the first place,
essential; and what is equally important, a fitting place of
ebservation at the stern of the vessel, with ten or Ss elve feet
of the water bend. In my own case, the quarter gallery of a
1500-ton merchantman afforded the best of all look-out
-ports ; and from it I was enabled to use the casting net about
to be described with ease and certainty. In the clear blue
water of the open sea it is astonishing how rapidly the eye
accustoms itself to detect creatures of the minutest size; and
how readily it learns to distinguish, even in the small
patches of calm water between each wave when a considerable
sea is running, any object that may chance to be swimming
near the surface. Nor is this confined to the portion of sea
immediately below the observer, but it can be done at a
distance of several yards. In order to embrace this distance

VOL. VII. B

2 WALLICH, ON APPARATUS FOR DREDGING, ETC.

the following casting net was constructed, and in the course
of a short practice it became easy to pitch this net, quoit
fashion, over any object within such range.

A hoop is made of half-inch rod iron, two feet eight inches

i
co)

a. Copper cylinders, closed at lower end. 3. Valve with curved spring.
c. Stud for forcing up the valve plate on touching bottom. v. Lron rod.
gE. Weight.

Fig. 1.—Showing position of apparatus whilst sinking, the valve being
closed.

Fig. 2.—Showing position on reaching ground, the valve being opened.
Fig. 3.—Showing tilting rods, as seen from mouths of cylinders.

in diameter. At any point in this hoop a ring or eyelet-hole
is formed by a loop of the rod, for attachment of the line.
Sewn round the hoop is an oblong bag, the bottom of which
is not tapered off, but allowed to remain square, the material
called crmoline being at once the strongest, cheapest, and,
from its open web, the best adapted for the purpose. This

WALLICH, ON APPARATUS FOR DREDGING, ETC. 3

bag is about a yard or somewhat less in depth. The lne
must be stout, such as is used for deep-sea fishing, for in-
stance. A coil of this is held loosely in the left hand. The
right grasps the ring, close to the eyelet-hole, in a horizontal
position, and throws it with a twist, just as a quoit is thrown,
with the mouth of the bag downwards, over the object to be
captured ; as much line as is necessary being allowed to slip
without check out of the left hand.

The hoop instantly sinks, the pervious nature of the ma-
terial forming the bag offering little or no resistance. The
moment it has passed deep enough to embrace the object, a
sudden haul on the hne tilts the mouth of the hoop up verti-
cally, the sides of the bag at once collapse on each other, and
the enclosed object is secure. So readily does this simple
casting net answer its purpose, that at one cast in moder-
ately calm weather it brought up a couple of open-sea
mackerel, each a foot and a half long; and molluscs, tuni-
caries, ascidians, and other creatures of various kinds, were,
with ease, brought within reach. This casting net is, of
course, equally available on the shore, off a pier, rocks, &c.

In the drag net used by me, I found it of great advantage
to have the hoop made also of iron, but of a triangular shape,
instead of the ordinary round form, each angle having an
eyelet-hole or rmg, whereupon to attach the three connecting
intermediate lines. By lengthening one of these three lines
somewhat, the hoop was always kept with the same angle
downwards, and thus prevented the constant turning, and
twisting, and jerking, attendant on the use of the ordinary
circular hoop, whenever the ship’s rate exceeded four or five
knots.

For soundings, in moderate depths, up to three or four
hundred fathoms, the following apparatus is most efficient :

A half-inch rod of iron, four and a half feet long, is bent
at its centre to an angle of about 150°. At one end a loop
is formed for attachment of the line; at the other, about six
inches is reflected on itself in the same plane as the angle
referred to, and within this reflected portion is jammed the
connected band of two copper cylinders, soldered strongly
together side by side; their closed ends being of course di-
rected outwards, their open mouths towards the angular part
of the rod. In order to prevent regurgitation and loss of con-
tents, a valve is formed of a plate of metal sufficiently large to
extend right across the mouths of both cylinders. In the
centre of this is cut a slot or aperture, to admit of vertical
motion to the extent required, the plate being attached by a
curved, moderately strong, flat spring to the farthest end of

4 WALLICH, ON APPARATUS FOR DREDGING, ETC.

the rod or cylinder, and at the centre of the margin of this
plate, intended always to rest on the bottom, is attached a
stud of several inches in length, whereby the moment contact
with the surface of the ground is made the plate is made to
rise and admit whatsoever presents itself. ‘To complete the
apparatus, a twelve- or fourteen-pound lead weight is cast
round the upper portion of the knee formed at the angle
of the rod; a small rod of iron, about eighteen inches in
length, is riveted at the outside of the mouth of each cylinder.
This rod is bent somewhat backwards, its use being, in event
of the cylinders touching the bottom in a lateral direction, to
tilt them forward again. Lastly, the line being attached, the
apparatus is ready for use.

In sounding, it should be hove astern as far as possible.
Now it will be observed that, owing to the angle in the iron
rod, and the heavy weight appended to a particular part of
it, whilst in the act of sinking such weight will remain per-
pendicular, whilst the cylinders will be held out from the
perpendicular to the extent of the angle. They will never-
theless touch the bottom first at their outer closed ends,
which will then act as a fulcrum, on which the rod will turn
till it also reaches the bottom. The line bemg now hauled
upon, each cylinder acts as a scoop, and on leaving the
surface is effectually closed up by the return of the valve to
its normal position.

Of course soundings with this apparatus, or indeed with
any apparatus, can only be effected in perfectly calm weather
or at anchor, its advantage over other forms consisting in
its simplicity, its certain action, and the great quantity of
material it is capable of bringing up. No doubt it admits
of mechanical improvements in many ways, and these could
with ease be carried out; but as the organisms found at the
sea bottom are daily engrossing more attention, whilst those
procurable near the surface are not only interesting in them-
selves, but can be made to yield up the minute ‘structures
they feed upon, and from which the microscopist eliminates
many a choice repast, I trust the foregoing detail may not
prove without interest.

Norers zx Reprty to Dr. WaLKEeR-ARNOTT.
By Dr. Donxin.

Proressor Walker-Arnott having considered it proper to
attack me in the preceding number of this Journal (p. 164),
on certain facts demonstrated by me in my paper on the
‘Marine Diatomacee of Northumberland, * I consider it
my duty to offer a reply.

I confess myself at a loss to comprehend Dr. Arnott’s
reason for accusing me of having acted towards him with
want of courtesy. But J presume it is because I have pointed
out, in the postscript of my paper, that my P/. rectum, n. sp.,
is identical with that form to which he has given the cogno-
men of Apr. Ralfsii. Dr. Arnott imagines I had no right to
mention his name in the matter, because he had not then
published his description of the form in question. But he
evidently forgets that at the period when the postscript of
my paper was written, slides had been distributed amongst
observers (mounted from Mr. Ralfs’ Penzance gathering)
containing this species in abundance, with his—Dr. Arnott’s
—generic and specific name appended. + Thus, then, it is
evident that the name given by Dr. Arnott to a particular
diatomaceous form became, actually and virtually, published.
I therefore, after examining well authenticated specimens of
this same form, had a perfect right to criticise, in any becom-
ing manner, Dr. Arnott’s conclusion and synonyme; and
more especially so when I knew that I had previously de-
scribed to the Microscopical Society{ the very same species
under a different name.

Now it appears to me that Dr. Arnott would have acted
much more in that spirit which ought to guide every philo-
sophical discussion, had he, instead of accusing me of being
guilty of a grave social offence, attempted to refute the accu-
racy of my assertions, and to establish his own hypothesis on
a firmer and more indestructible basis. But since he has
declined to do so, I must, of necessity, call his attention still
more closely to the error he has committed in referring the
subject of dispute to the genus Amphiprora. On reauin,
Dr. Arnott’s description, which, he will permit me to observe,
is very vague and without anything specially diagnostic, of
Apr. Ralfsii, in the last volume of this Journal, p. 91,

* ¢Trans. Micros. Soc.,’ vol vi.

+ One of these slides was sent to me by an esteemed correspondent,

Mr. Roper, and another from Dr. Montgomery, of Penzance.
t On the 21st of October, 1857.

6 DONKIN, IN REPLY TO WALKER-ARNOTY.

and his subsequent foot-note, p. 164, it is clearly apparent,
that he supposes this form to be an Amphiprora because the
valve is carinated—the carina being constricted in the middle
—and the striz transverse. Now, on the other hand, I have
shown* that the structure of the valve (there being two sets
of strie, one long., the other ¢rans.), together with its peculiar
outline and sigmoid median line, and also the absence of
ale, or lateral plates, as seen in the F.V., prove that it is
a true Pleurosigma. I have likewise pointed out,t+ that a
carinated and constricted F.V. is not, when taken in the
abstract, a generic character, and ought not longer to be relied
upon as such. This assertion is amply proved by Pl. cari-
natum { (a genuine Pleurosigma, with oblique stri, easily
resolvable in the F.V.), which has a very strongly keeled and
constricted valve. After a careful and frequently repeated
examination of all our genuine British species, I am con-
vinced that the presence of ale,$ attached laterally to the
valve, constitute the only true generic feature of the Amphi-
prore, while the carinated and constricted F.V., though
always, more or less, present, is merely of secondary import-
ance, being possessed by several species of Pleurosigmata with
straight valves ; thus proving a close natural affinity between
the two genera. Therefore, as Dr. Arnott admits the absence
of ale in Pl. rectum (alias Apr. Ralfsii), his attempt to refer
it to the genus Amphiprora is contrary to analogy, and simply
a violation of the law, which has been observed by all compe-
tent observers, in placing new species in this latter genus.
With regard to the markings of the Amphiprore, I may fur-
ther add, that when striz are present there is only a single
set, transversely arranged. This peculiarity is of consider-
able importance in distinguishing them from their allies, the
Pleurosigmata.

Dr. Arnott, however, will probably object to these conclu-
sions, having taken upon himself to ignore the existence of
any such species as Pl. carinatum ; he denies the fact of its
having oblique striz, and observes: “I do not believe the
stri are oblique, but only appear so in consequence of the

osition of the light.”? Now, I wish to know on what grounds

r. Arnott considers himself justified in contradicting the
statements of others on any scientific subject, without
having in the first instance satisfied himself, by actual obser-

* See my description of Pd. rectum, n. sp., ‘Trans. Micros. Soe.,’ vol. vi.

+ In Op. cit., Postscript.

+ See description of this species, Op. cit.

§ The universal presence of ale in the genus Amphiprora was first pointed
out by my late lamented friend, Professor W. Gregory.

DONKIN, IN REPLY TO WALKER-ARNOTT. a

vation, that such statements are erroneous. Now, as he has
never examined a single specimen of Pl. carinatum, his ob-
jections to this form are simply imaginary, and being, there-
fore, of no importance, according to the principles which
regulate the determination of every scientific truth, they are
unworthy of refutation. It may not be amiss here to repeat,
even emphatically, that my published description of this
remarkable species is perfectly correct, both as regards the
shape of its S.V. and F.V. and as regards the nature of the
strie, of which there are two sets obliquely arranged, and
easily resolvable, with sufficient power and proper illumina-
tion, into cellules, having a quincuncial arrangement; but
owing to the valve being compressed laterally towards the
median line into a keel, these markings are most easily seen
on the F.V.

Dr. Arnott pronounces my Pl. arcuatum to be Pl. fasciola.
In reply, I must observe that whereas the former is a strictly
marine form, being only found on the open shore or in deep

“water, the latter only occurs in brackish water, in the living
state. But independent of this very important fact, the two
forms present structural differences of a specific nature, which
cannot be ignored. In the first place, the extremities of Pl.
arcuatum have each a strong double curve, that is, each is
strongly sigmoid between its base and its apex. Whereas
each extremity of Pl. fasciola has only a single curve, or in
other words, is gently arcuate between its base and apex. In
the second place, the extremities of Pl. arcuatum are much
longer than those of Pl. fasciola. In my figure of the former
species the extremities are represented much too short, a fact
kindly pointed out to me by Dr. Greville. Thirdly, the striz
are much finer than those of Pl. fasciola.

As to my Apr. duplex being the same form as Apr. palu-
dosa, as alleged by Dr. Arnott, I must observe that the very
fact of the former being a strictly marine species, while the
latter, according to the late Professor Smith, is the only
fresh-water form in the whole genus, renders such an allega-
tion simply untenable. Besides, a mere examination of
figures of the two forms cannot fail to convince any one of a
specific difference.

Dr. Arnott says my figures and descriptions lead him to
believe that my Pl. Wausbeckii and minutum, and probably also
angustum, are the same form as Pl. rectum, or, in other words,
his Apr. Ralfsii. I am, however, led to suspect that his
examinations of my descriptions, at least, must have been
exceedingly superficial, otherwise he could not have arrived
at such a conclusion. Dr. Arnott also states his belief that

8 DONKIN, IN REPLY TO WALKER-ARNOTY.

all these last mentioned species occurred in Mr. Ralfs’ Pen-
zance gathering. Repeated examinations, however, have con-
vinced me that this is an error, as Pl. rectum is the only form
T can detect. It is necessary to state that my Pl. Wausbecku
is the variety of PJ. balticum, figured by Professor Smith im
his ‘Synopsis ;’ but I am at a loss to understand why he con-
sidered it as such. There is certainly nothing more than a
generic resemblance between the two forms as regards outline,
colour, and the relation of the median line to the margin,
while the strie of Pl. Wausbeckii are considerably finer than
those of Pl. balticum.

I confess myself at a loss to understand Dr. Arnott’s
hypothesis, which enables him to look upon the two members of
my new genus Towonidea as accidental or twisted conditions of
Pl. strigosum, angulatum, and estuarii, produced by a peculiar
process. This assertion I do not credit; and nothing short
of actual observation, I feel assured, will satisfy any partial
inquirer as to its validity. It would be well, therefore, were
Dr. Arnott to state whether he has seen such a phenomenon
take place, and if so, to describe it. For undoubtedly any
physiological or pathological process which can effect so great
a change, not only in the general outline, in the relative
position of all the parts, and in the cellular structure of the
siliceous valve of the Diatome, must of necessity be a most
singular one, and its demonstration by Dr. Arnott cannot fail
to attract that interest which falls to the lot of every important
physiological discovery.

These remarks, I trust, will be amply sufficient to show that
Dr. Arnott has, on very insufficient grounds and in no liberal
manner, accused me of creating “‘swpposititious’”’ species out of
mere varieties, and thereby encumbering science with useless
and unmeaning names. As to the regret which he expresses
at what he calls “rushing into print,’ without making myself
acquainted with what others are doing, I must observe, in
reply, that while, in my paper, I have studiously avoided any
attempts at plagiarism by adopting as my own the published
discoveries of other observers in the same field, I was at the
same time unable to command the supernatural assistance of
an Asmodeus, to unveil to my observation their present
doings and cogitations. It is certainly true, as stated by Dr.
Arnott, that I had described certain species which had
previously been found by M. De Brebisson at Dines. Of
this fact, however, I was entirely ignorant until a few days
prior to its publication; when M. De Brebisson himself
sent me some slides, mounted from his gathering made in
that locality, in order to ask me whether the new species

DICKIE, ON DIATOMACEH AND MOLLUSCA. 9

contained on them have any resemblance to those discovered
by me on the Northumbrian shore. M. De Brébisson at the
same time informed me that he had not published any
description of these new forms. In January last I sent him
a copy of my paper, and after reading it he wrote to me to
say that he had adopted all my names for those particular
species, with which he was previously acquainted ; thus ex-
onerating me from all blame in the matter. On this ground,
therefore, Dr. Arnott ought not to express his disapprobation.

On a Derosit of Diatomacr® and Mouuuvsca, in the County
of Antrim. By G. Dicxiz, M.D., Professor of Natural
History, Queen’s College, Belfast.

In a field at Bellahill, a few miles from Belfast, and in the
County of Antrim,a sepulchral tumulus has existed from time
immemorial.

In the end of January last, this mound was opened, under
the superintendence of the Rev. A. J. Lee. It seems to have
had for its foundation the surface of the ground where it
was reared ; that is to say, there was but little previous exca-
vation, the ashes of the deceased having been placed on or
near the surface, and then the earth and other material heaped
over them. Mr. Grattan, of Belfast, first directed attention
to the nature of part of the material dug out from the foun-
dation of the tumulus, having recognised it as one of those
deposits, called fossil earths, now known to be of very general
occurrence.

Two varieties of the earth were found—the deepest in thin
layers among peat, pure white, and entirely siliceous; the
other more superficial, in large masses, of a buff colour, and
effervescing freely with an acid. The presence of calcareous
matter in the latter was easily accounted for, by the ex-
istence of fragments and entire shells mixed with it. Two
of these are common fresh-water mollusca, viz., Lymneus trun-
catulus and Planorbis vortex ; the former was by far the most
abundant of the two. Along with them were found four
well-known land species, Helix arbustorum, H. rotundata,
Zua lubrica, and Clausilia nigricans ; these were very rare,
compared with the fresh-water species.

After careful examination of the deposit, I found the fol-
lowing Diatomacee :

VOL. VII. c

10 DICKIE, ON DIATOMACEH AND MOLLUSCA.

Lpithemia turgida, Sm. Pinnularia viridis, Sm.
45 gibba, Wirtz. 5s divergens, Sm.
= zebra, Kitz. I radiosa, Sm.
» Hyndmanni, Sm. (very Synedra delicatissima, Sm.
rare). Cocconema cymbiforme, Khr.
Amphora ovalis, Kitz. = cistula, Eby.
Cocconeis placentula, Khy. Gomphonema vibrio, Khr.
Campylodiscus costatus, Sm. (very es olivaceum, Ehr.
rare). if capitatum, Khr.
Surirella ovata, Sm. (very rare). a tenellum, Sm.
Navicula ovalis, Sm. Odontidium mutabile, Sm.
Bs Jirma, Witz. Denticula sinuata, Sm.
es liber, Kitz. Orthosira orichalcea, Sm.
. patula, Sm. Mastogloia Grevillii, Sm.
$3 rhomboides, Khr.

Three or four of these were not at first observed by me,
but recognised by Professor G. Walker-Arnott, of Glasgow,
to whom specimens were sent.

Mr, Lee, in his notice of the tumulus,* states that its shape
was somewhat different from that of others in Ireland, “being
more flattened and less elevated ;” and further adds—“ This
may be accounted for by the continued action of the waters
of the lake, which probably surrounded it for centuries ; the
former existence of which is proved, not only by the geological
formation of the locality, but by the remains of fresh-water
shells, and lake Infusoria found in the substratum on which
the tumulus stands.” Respecting this inference, I would
remark that it is totally at variance with the facts observed.
It is obvious that a tumulus, consisting of comparatively
loose material, could not have existed for any length of time
exposed to the action of water, often more or less liable to
agitation by winds and floods. But supposing the mound
capable of resisting the action of the lake for “ centuries,”
how could peat be produced under it, and how could the
Diatomacez have lived and propagated beneath it, and much
less the fresh-water Mollusca? It is obvious, moreover, that
the shells of terrestrial species, accidentally mixed with the
others, could not possibly have been drifted to such a place
as the foundation of a heap of mould, seven feet in height
and forty-five in diameter. I visited the locality in company
with my friend, Mr. James MacAdam, and having examined
the facts above mentioned, I never doubted that the tumulus
had been raised long after the draining of the lake. Mr. Lee
states, that ‘“ the character of the remains discovered in this
tumulus incline us to fix the date of its formation anterior
to the Christian era.” Tong previous to this epoch the lake
had disappeared, and the physical conditions of the place

* © Ulster Archeological Journal,’ May, 1858.

WEBB, ON A LOOSE CARTILAGE. 1p)

been completely altered, for there seems no reason to conclude
that since the raising of the tumulus, at a time when the
surface of the field was accessible, there had been such im-
portant changes in the district as would be implied by the
accumulation of a large body of water, upwards of seven feet
in depth, and the subsequent drainage of the same.

Notes of the Microscopican Examination of a Loose
CartitacEe from the Kner Joint. By W. Woopuam
Wess, M.D., Lecturer on Histology and Minute Anatomy
at the Middlesex Hospital.

Tue cartilage on which these observations were made, was
removed from the knee-joint of an elderly man in the Norfolk
and Norwich Hospital, by my friend Mr. Cadge, surgeon to
that institution. It was of somewhat larger size than is
usual in such formations, and was of a flattened and elon-
gated shape. Its general appearance was that of a nodule of
fibro-cartilage, but the section towards the interior gave rise
to a rough gritty sensation, and showed a darker and uneven
surface. When dried, the internal parts were quite opaque,
and crumbled away if scraped.

By all the older writers it seems to have been regarded as
an established fact that the denser portions of these loose
cartilages were of true bony character; and even in Wedl
and Rokitansky, we only meet, in reference to them, with the
vague terms of ossification, cretification and calcification,
none of which convey any definite information as to the
exact histological condition of the structures, or their mode
of growth.

Before being submitted to me for examination, the spe-
cimen had been much handled and kept in dilute spirit. It
was, therefore, not in the most favorable state for ascer-
taining the nature of its superficial investment ; but I believe
that epithelium had been present on those parts least exposed
to pressure, though on the flatter portions there was no trace
ef such cells. It is only by dealing with the most delicate
preparations that any accurate knowledge of these growths can
be arrived at, and even with them a micro-chemical analysis
1s necessary.

A very thin vertical section, under a power of 220, brought
into view the following appearances. On the surface was a
condensed layer of fibrous tissue which had a_ horizontal
disposition, and swelled up and became gelatinous with acetic
acid. This gradually lost all indications of fibrillation, and

12 WEBB, ON A LOOSE CARTILAGE.

merged into a hyaline matter, studded with imnumerable
flattened and elongated nuclei, very closely applied to each
other, and arranged in strata towards the exterior, but
becoming more and more scattered and expanded as they
were traced inwards. The several stages of vacuolation and
formation of cell-spaces could now be distinguished around
these isolated nuclei, while the periplastic matter was clearer
and without any marks of definite organization. Among the
fully formed cells the usual tendency to multiplication by
division showed itself, and somewhat further in this tendency
assuming, as in ossifying cartilage, a linear direction, parallel
and perpendicular rows of cells, with but a small amount of
intervening matter, constituted the bulk of the substance.

Some of the mature cells manifested a change in the nature
of their contents. These had hitherto been clear and fluid,
with the exception of the nucleus, but now opaque granular
material began to be seen. The end-to-end cells also
coalesced with a regularity which converted them imto short
tubules, closely packed together in groups. These tubules,
or many-celled spaces, soon became filled with an amorphous
saline deposit to such an extent, that all traces of cell-wall
and periplastic matter were concealed, and the mass appeared
but one uniform solid block. The disintegrating and analytic
influence of reagents was here required to demonstrate the
actual condition of this reputed bone.

Dilute caustic soda, by expanding the intercellular matrix
disclosed the whole series of tubules or spaces originating in
the fused cells of which the part was made up, and so
isolated the casts about which the cell-walls were accurately
moulded. The addition of hydrochloric acid caused the
entire solution of these concretions, with effervescence, and
left exposed the empty and bare cell-walls, retaining their
perfect contour, with the nuclei still adhermg in their
natural position and integrity. Longitudinal irregularities
or puckerings, produced no doubt by chemical action, gave
to these walls a sort of fibrous look. The very centre of
the mass consisted of numerous stellate groups of these
elongated spaces with cretaceous contents, round the ag-
gregate of which were arranged the perpendicular rows of
cells undergoing the process of fusion, and fillimg up of
their areas.

There was no indication of nerve, vessel, bone-corpuscle,
or other structure, which could warrant the classification of
this abnormal articular growth as an osteophyte. Beyond a
certain depth from the surface, all the changes taking place
were those of retrograde metamorphosis.

SCHULTZE, ON DIATOMACL&. 13

The description follows the appearances, as seen in passing
the eye over a thin section from the circumference to the
centre.

Prenomena of InrerNaL Movemunts in Diatomacra of
the Nortn Spa, belonging to the GENERA CosciINopIscus,
DentIcELiaA, and RutzosoLtenta. With a Plate. By Pro-
fessor Max ScHuULtzeE.

THe sea around Heligoland is rich in large Diatoms,
which are frequently brought up in considerable numbers by
the fine net. Several of the species very abundant there
have been found by Ehrenberg at Cuxhaven, as Coscino-
discus, Zygoceros, Eucampia, Triceratium (‘Abhandl. d. Akad.
d. Wiss. z. Berlin,’ 1839). Others are still not known out
of that region, as Chetoceros (Brightwell, ‘Quart. Journ. of
Micr. Science,’ 1856, p. 105, tab. vii), Denticella, Rhizoso-
lenia.

By far the most numerous forms of the genus last named
occurred towards the end of the autumn. The Rhizoso-
lenia are readily to be distinguished with the naked eye, and
were wanting on no day in the excursions undertaken im com-
pany with my father and the Messrs. G. Wagener, Lieber-
kthn, and Kupfer. In a glass containing them one
perceives, by transmitted sunlight, a glittering, proceeding
from small rods of a hair-like fineness, which refract and
bend the light, like crystals of Cholesterme, but more
strongly, so that they shine in all the colours of the rainbow.
The rods not unfrequently attain the length of 2 to 3 lines.

Perfect examples of the genus Khizosolenia Khrbg., so
far as I am aware, have only been found by Brightwell up to
the present, and were first mentioned in No. XX of the
‘ Quart. Journ: of Micr. Science,’ 1857, p. 191, and were
afterwards figured in the later numbers of the same
Journal. These ‘being all procured from the stomachs of
Ascidians and Salpze, as also from Noctiluca, were seen filled
in part with organic, but not living, contents. Still, Bright-
well, in the last-mentioned place, states, from his own obser-
vation, that Rhizosolenia setigera shows a movement like
other Diatoms, in which the tubes push themselves slowly
backwards and forwards. Here also it is mentioned that
Rhizosolenize occur freely, swimming in the seas of warmer
latitudes.

Herr G. Wagener first drew my attention to the peculiar
currents of granules occurring in the Rhizosoleniz, which

14 SCHULTZE, ON DIATOMACES.

induced me then to make further researches among other
Diatoms, where they had been observed by G. Wagener, also
in Coscinodiscus, and finally I saw them in a large Denticella.
Great transparency of the siliceous coats is necessary for a
clear observation of the streams of granules. Those forms
of Coscinodiscus the sculpture of whose shells is very delicate,
as C. centralis, Ehrbg. (‘ Micro-geologie,’ tab. xxu, fig. 1),
with which a form common at Heligoland agrees, are
consequently more fitted than others, such as C. radiatus
and C. patina, Ehrbg., which are finely marked, and possess
an opaque, sharply sculptured shell. For the same reason
Triceratium, of which many species occur at Heligoland, is
not adapted for observation. In several Diatoms placed
together, whilst living, in a fluid adapted for the preservation
of Meduse,* could be observed, im addition, a radiate,
threaded arrangement of the organized contents, corre-
sponding with that in which the granular streams would have
been observed in life, as, for instance, in the large trans-
parent Navicula angulata.

The whole movements I have seen neither in Rhizosolenia,
nor in Cosinodiscus and Denticella. The internal move-
ments are of the following kind :

Coscinodiscus and Denticella (figs. 11—13) show, in the
living state, a nucleus placed almost in the centre, but still
drawing near to one of the side walls ; it 1s a round, colourless
vesicle, of the size of a human blood-corpuscle, with a large,
strongly refracting nucleolus—it might be taken for a cell
with a nucleus, but which last would then want the nucleolus.
Around this body is found an accumulation of a finely
granular colourless mass, from which radiate a multitude of
finer and coarser cords, passing through the internal space of
the Diatoms, which is of a water-like clearness, in all direc-
tions. They all come to an end at one of the surfaces
of the siliceous covering, lying closely round an exceedingly

* This fluid, consisting of common salt Ziv, alum 3ij, sublimate gr. iv,
dissolved in two quarts of distilled water, is well adapted for the preserva-
tion of small organisms, procured by fishing with the fine net in the sea.
One rinses out the corner of the net in a glass filled with this solution in-
stead of sea-water. In this manner, after several repetitions, one obtains
a sediment which may serve as a mine for the whole year. Noctiluca,
Echinoderm, and Annelid larvee, Entomostraca, Diatoms, Polythalamiz, and
Polycystiniz are admirably preserved, both in their soft parts as well as
their hard structures. To make them transparent, glycerine should be
afterwards added. In the circumnavigation of the world, glasses containing
this fluid, each filled at different places and noted, would furnish richer and
better material for the study of geographical distribution and variety of
forms than searching the stomachs of animals or the filtering of several
bottles brought back filled with sea-water.

SCHULTZE, ON DIATOMACES. 15

delicate layer of the same finely granular matter. In the
latter, as in the fine granular substance enveloping the
nucleus, and frequently in an incompletely fixed state of the
wall, entirely concealing it, are imbedded vesicles of a
coloured material. These are ochre-yellow, and round or
somewhat pointed; they are of the latter form in Denticella.
They lie close to the siliceous covering, either presenting an
entirely uniform distribution at equal distances from one
another (as m the examples delineated), or are arranged in
reticulated cords, uniting among each other, as has been
more than once seen in Coscinodiscus. In the threads and in
the finely granular external layer are found appearances of
currents. Specimens brought freshly from the sea, or kept
at most some hours in a glass, are alone fitted for the ob-
servation of these. From the finely granular mass sur-
rounding the nucleus the stream goes in, and to the, as it
appears, more homogeneous, if not structureless, mass, con-
sisting of threads at the periphery; and in the same threads,
or others, different granules return back to the centre. The
threads are thickest near the nucleus, and attenuate them-
selves on their way by division, anastomosing reticulately
with one another, till, in their finer distribution, they repre-
sent a delicate web lying close to the siliceous coat, in which,
or in a more homogeneous layer, immediately on its exterior,
the coloured vesicles are imbedded. The nucleus does not
always lie close to the siliceous covering; it may also
approach the middle of the imternal space. Coscinodiscus
possesses a form like a shallow round box, whose bottom and
top is arched like a watch-glass. If one views such a body
from the side, and the nucleus with the granular mass
enveloping it is situated in the middle, between both side
walls, there goes more frequently a stronger cord of granular
matter from it to the centre of the latter. In this way the
middle appears possessed of a darker axial cord. In such a
middle situation, the nucleus seems to increase before the
commencing propagation by division. After the appearance
of two new watch-glass-shaped walls, with their convex
surfaces turned to one another, that sprout of division
possesses a nucleus closely adhering to the newly formed wall.
So also in Denficella (as fig. 12 shows), where certainly the
situation of the nucleus is disclosed only by the accumulation
of the darker granular mass, as the centre of the radiating
threads. The coloured vesicles are omitted in this figure ;
they presented the same uniform destribution as in fig. 11,
so that a complete removal of the same seems not to interfere
with the appearance of the division.

16 SCHULTZE, ON DIATOMACEE.

Somewhat differently does the granular stream flow on in
Rhizosolenia. The long, completely transparent, very delicate
siliceous tubes possess yellow contents, as Brightwell indeed
saw; and certainly this yellow colour is dependent on
coloured vesicles of a long oval, nearly rod-shaped figure,
almost equaling in their long diameter those of Coscinodiscus
and Denticella. They lie imbedded in a colourless substance,
containing fine granules, which is again the seat of the
appearances of currents, in which here, however, departing
from the Diatoms first described, the coloured vesicles take a
lively part. A denser opaque accumulation of the granular
matter and coloured frustules, situated sometimes in the
middle, at others nearer one end of the tube, in which a
nucleus, as in Coscinodiscus and Denticella, could not be seen,
presents itself as the centre of the currents. These do not
radiate in all directions through the middle of the tube, but
confine themselves closely from the beginning to the surface
of the siliceous coat, and run off usually as fine, stretched,
parallel threads, until, in the pomted end of the tube, they
unite themselves again to a generally small expanding opaque
mass. I once counted in the circumference of the tube sixteen
such granular threads, flowing parallel and beside each other.
The current is in each of the threads double. Small
granules, flowing in a more homogeneous substance, some-
times more quickly, at others more slowly, collect them-
selves together here into a little mass; they are there seen
only singly, projecting out on the margin beyond the surface
of the thread, or apparently entirely imbedded in it. Fre-
quently one or many of the coloured frustules are laid hold
of by the current and carried far away to a distance; others
lie quietly between the streams in a perfectly undisturbed
layer. Bridge-like joiings, meltings away, and divisions also
occurred. So much I remember. Alas! more accurate
notes I did not make. It may be that the phenomenon, for
that reason, will commend itself to others for further
research.

The granular currents described, namely, those in the
interior of Coscinodiscus and Denticella, entirely resemble
those known to exist in Noctiluca. In it they proceed from
a dark mass, which eccentrically took the place on which
the spherical body possesses a heart-shaped recess, and
radiate in all directions in the interior of the hollow space of
the body, which is filled with a clear fluid, passing away into
an exceedingly fine network of streams immediately under
and surrounding the skin, and ultimately melting away with
skin itself, which (if we would transfer an idea from the

SCHULTZE, ON DIATOMACE.®. 17

plant-cell to the Noctiluca, only represents the most external
layer of the proto-plasm) is of the nature of clear albumen ;
this also appears not to be wanting m Coscinodiscus, though
in it covered by the siliceous coat, as itis m most plant-
cells by one of cellulose. The currents of granules are also
perfectly similar to those found in the extended threads of
Gromiz, Polythalamiz, and Polycystinie. Unger has briefly
(‘ Anatomie und Physiologie der Pflanzen,’ 1855, p. 282)—a
view previously more specially propounded by Cohn (‘ Nach-
trage zur Naturgeschichte des Protococcus pluvialis, Aus d.
Leopoldinischen Akademie-Shriften)—classed together the
currents in the fluid contents of plant-cells (2 8), the hairs on
the filaments of Tradescaniia, with the phenomena presented
by the threads of Ameba porrista, or the Polythalamiz, as
I describe them, and the movements of the protoplasm he
declares are exactly similar to those of the so-called sarcode
of the Rhizopoda. I have compared the frequently described
phenomena in the hairs on the filaments of Tradescantia
with the currents in the Diatoms, as well as in the threads
of the Rhizopoda, and must acknowledge their great simi-
larity. I chose for the observation Tradescantia procumbens,
the hairs of whose filaments present very transparent cell-
walls and entirely colourless contents; the latter, in Tr.
zebrina, for instance, being more or less real, detracts some-
what from the distinctness of the movement phenomena.
In the former, also, the granules are larger, and the material
of the threads apparently more homogeneous. From the layer
of protoplasm enveloping the nucleus proceed several thicker
or thinner threads, traversing the cell im all directions, more
frequently, however, lying close to the cell-wall (as in Rfi-
zosolenia). They consist clearly of a basic material, with
strongly refracting granules imbedded in it. The latter flow
in the interior, or, as it were, on the surface of the threads,
either in one direction only, or in opposite directions at the
same time in one and the same thread, as may not unfre-
quently be observed. In the broadest threads this double
direction of the current is nearly universal, but it occurs also
in the finest, which are almost imperceptible. The granules
generally pass by each other undisturbed, or it may happen
that one is taken back by the others—a proof that the double
direction of the stream is not due to two separate threads.
Individuals flowing quickly overtake others going more slowly
in the same thread, and may then, as I once saw, suddenly
turn back and proceed in company. The threads divide
themselves frequently in a forked manner, and a granule
reaching the point of division stops before committing itself

18 SCHULTZE, ON DIATOMACES.

to the one or the other way. The shape and direction of the
thread are subject to continual change. The forked division,
for instance, proceeds from the base of the threads at the
cell-nucleus to the other ends, which meet together on the
internal surface of the cell-wall. Or it forms out of the
forked division a bridge to a thread lying close beside it,
while the branch part melts away with this. The bridge then
runs upwards or downwards between both threads; it shortens
itself, while the latter draw near one another ; finally they
melt away completely with each other into one, so that now
a broader stream flows where there were formerly individual
fine threads. On the internal surface of the cell-wall is
found a thin, coherent, protoplasmic layer. So it appears
after the application of reagents, which cause it (the primor-
dial utricle) to become shrivelled. By means of syrup I
could bring out here what A. Braun arrived at in the Cha-
race (‘ Monatsberichte der Berliner Akademie d. Wiss.,’
1852, p. 225). The cell-contents, sharply circumscribed,
drew themselves back from the membrane of the cell; besides,
the appearance of currents in the interior still continued for
along time. In this way one can convince himself that the
granular currents and fluctuations (for such are here fre-
quently alone present in places), occurrmg in the mid-layer
of the protoplasm, are not related to the last layer (Haut-
schicht, Pringsheim) but only to the inner stratum of the
parietal layer (granular layer). In this way those in Nocéi-
luca are comparable with the above. In distilled water I
have seen the appearance of a stream maintain itself in indi-
vidual cells for twelve hours, and in thin syrup for twenty-
four. It would be well worth the trouble to try the influence
of a series of solutions on the movements described, perhaps
like those made by Kolliker with the spermatozoa. In this
way interesting disclosures might be expected.

The movements remarked in the protoplasm of plant-cells
ought not, in my opinion, to remain neglected, as they may
act as an explanation of the mysterious appearances of life in
the sarcode threads of the Rhizopoda, and I recommend the
comparative study of the former to those who consider the
threads in Polythalamia as possibly or probably a compound
of small cells. In Tradescantia the same phenomena occur
in undoubted cell-contents, which must, therefore, be related
to animal life.

Of Rhizosoleniz I have observed two different species.
The largest, and by far the most abundant, is undoubtedly
identical with Brightwell’s R. styliformis, described in the
‘Quarterly Journal of Microscopical Science,’ Jan., 1858,

——e— ee

SCHULTZE, ON DIATOMACE. 19

xxii, p. 94, and delineated in Plate V, fig. 5. The tubes
are cylindrical, pretty abruptly pointed at both ends, and
furnished at the extremity with a small siliceous point, ap-
parently solid, or at least with very thick walls, sharply
marked off from the cavity of the cylmder. The pointing of
the species, according to various positions of the tube ob-
tained by rolling it round, originates nearly like a cut-out
quill-pen. The length and thickness of the tubes vary
much. I have seen them from 0-4 to 0:7” Par. in length,
and 0:025 to 0:04’" in thickness. The most examples are
found in the act of division, which is in an oblique direction,
while others consist of from three to six individuals cohering
together. Of such I have measured several. A. Four co-
herent individuals, 0°68", 0:42", 0:4", 0:46" in length.
B. Three ditto, 0°7'”, 0°76, 0°68” in length. C. Three
ditto, 0°72", 0°54'”, 0°52'” in length. D. Six individuals
attached to each other, 0°52”, 0°74", 0:5", 0°52'", 0-5” in
length ; the last was broken off; the entire length of the
tube was 3’. Characteristic of R. styliformis are the ringed
markings which the shell possesses. These appear not re-
markable in water, but come out very sharply after subjec-
tion to a red heat, or desiccation after previous treatment by
acids. I have taken pains in fig. 4 to give a most correct
drawing of the same, as they appear in that position of the
Rhizosolenia which resembles a cut quill-pen, with the cut
surface turned towards the observer. ‘The upper part of the
two individuals shown in fig. 3, still hanging together after
the division, turned round in its long axis towards the left
about 90°, would then present the same view as fig. 4. The
oblique falling-off side of the young ends is presented to the
beholder. On it, im the middle, is found a design like the
tip of a lance. It is, to look at, in a manner like an impres-
sion of the once closely applied end of another individual.
Here a confinement of the shell to the very last may take
place during the division, perhaps even an aperture in the
siliceous coat remains in the dark lines, a, a, which I could
sometimes nowhere discover. The ringed markings of the
shell are made by linear incisions, therefore the shell most
commonly breaks in the rings. A wider and finer marking
of the siliceous coat could not be discovered, either in the
red-hot condition or by the use of oblique light.

The second species, which is rarer in Heligoland, I have
named R. calcaravis (figs. 5—8). It is smaller than the
first, and occurs im solitary, not in numerous, individuals
adhering together. Length 0°20'’—0°25'"; thickness, 0°025.
Specimens of 0°25" already showed the oblique division in

20 SCHULTZE, ON DIATOMACE.

the middle. Once only I saw three individuals hanging
together, and of these one was caught again in the act of
dividing. Their lengths were 0°15, 0°15, and 0°225.” On
the siliceous coat I could not perceive a rimged marking.
The poimting at the ends is waved, and the extreme point,
. sharply marked off, as in R. styliformis, is bent like a bird’s
claw. The level of the curves of these points in the two ends
of one individual are not parallel, but cut themselves at a
sharp angle. The two specimens delineated at fig. 8 present
a provisional, not clearly explicable peculiarity. They were
found without organized contents. They adhered firmly to
one another, as they are figured, being only slightly changed
that the cause of their cohesion may be shown. ‘The length
of the specimen on the left was 0°2’”, that on the right 0°25’.
In both the upper point was broken off nearly at the middle ;
but a kind of termination was again effected by a very delicate
membrane. Both contained in the interior, moderately near
one end, two spikes of new individuals made fast to each other
im an inverted direction. I suppose these examples were
caught in the act of dividing, for which purpose they had
developed the new spikes in the middle. They may be released
later from their original situation by the death and subsequent
maceration of the contents. Lastly, the young points differed
from one another. Asis evident in figs. 9 and 10 (magnified
330 diam.) the point of the former has a double, strongly
refracting contour, while that of the latter is paler and more
delicate. Fig. 9 lay in the specimen figured on the right
above, and in that on the left below, a, a. Fig. 10 was the
reverse, 0, 6. After the division in the Rhizosoleniz, as also
in Coscinodiscus and Denticella, the siliceous covering of the
parent individual still remains for a long time uninjured over
the divided place (compare figs. Gand 12). After this is cast
off, the offspring of the division always adhere for some time
to one another. So hkewise in Rhizosolenia styliformis, as in
fig. 2, where the dotted lines indicate the original union by
the siliceous covering which is here at present wanting.
Specimens are frequently seen to whose free ends still adhere
portions of the already cast-off siliceous covering of the
parent. Rhizosoleniz broken off, close the opening with a
siliceous plate arched like a watch-glass. Still they appear,
in addition, immediately after the closure to develope a new
and regular terminal process. I have seen specimens of the
species, at least, which certainly show, if it may be so some-
what artificially explained, that the broken-off point, getting
placed inside the tube, may become incarcerated by the
ensuing closure.

SCHULTZE, ON DIATOMACEZ. 21

The Diatoms shown in figs. 11 and 12 must be referred to
the genus Denticella, if we consider Ehrenberg’s D. amita
(‘ Microgeologie,’ tab. xxx, A, figs. 2, 3, 7) asthe typical form.
They agree very closely with the form named by Bailey
Zygoceros (Denticella?) mobiliensis (‘‘ Microsc. Observ. made
in South Carolina, Georgia, and Florida,” ‘Smithson Contrib.,’
vol. ii, p. 40 of the separate copies, tab. 11, figs. 84 and 35),
which cannot be, however, a Zygoceros, but is a true Denticella,
as Herr J. Miiller informed me in reply to an inquiry
respecting his opinion. One might impute the difference
from our species to the inaccuracy of Bailey’s somewhat
rough drawing. The size Bailey does not mention. The
specimen given in fig. 1] measured 0°11” in length (without
the prickles), and 0:065'” in breadth. That in fig. 12 was
0°125'” in length, and 0:098” in breadth. The lengths of the
individual sprouts of division were 0:055 and 0:065'"; it was
thus much less than their breadth, which, in connexion with
the other measurements already given, presents a great
variety in form. Young specimens, at first released by the
division, sometimes appear broader than they are long, at
others longer than they are broad. Besides, there occurred
at Heligoland much smaller Denticelle, which (either the
young of our species or of a new one) appeared to have
originated in a different manner than by division. The cross-
cutting of our Denticella is barley-corn shaped, and ends
naturally above and below in two external projections. The
spines are placed internal to the projections, not in the two
lines uniting the projections to one another, but the one to
the right and the other to the left of them. Hence the
uneven appearance the one has compared with the other in
the two individuals caught in the act of dividing (fig. 12).

In water the siliceous coat appeared destitute of all finer
structure. With great pains two cross lines can be perceived,
running parallel to each other, which are shown in our
drawings. These are always at the same distance from the
upper and under ends, and approach more closely to one
another the shorter the individual. After the application of
a red heat, and by the use of oblique light, there is brought
into view a fine hair-like marking of the surface, as seen in
Navicula angulata. Such a fine clothing D. mobiliensis of
Bailey, from the coast of Florida, shows. After all the
information given, our Denticella will be easy again to recog-
nise. I have named it Denticella regia.

22

On some Conditions of the Crtu-watL in the Prrats of
Frowers, with Remarks on some so-called ExvERNAL
Seconpary Derrosrts. By 'Turren West.

In working over microscopic subjects generally, my atten-
tion was arrested by that well-known object, the petal of the
geranium, and the attempt to reconcile the appearances found
with the descriptions in books led to investigations, some of
the results of which are embodied in the following commu-
nication. How far these agree with the opinions entertained
by previous observers will best appear in the course of my
remarks.

It may be desirable to state at the commencement the
mode of examination followed. Considering the soft and
perishable nature of the structures to be determined, it
seemed essential that they should be viewed as quickly as
possible after being gathered, before any changes from the
natural condition of the parts in life could have taken place.
Some petals, as those of Clarkia, are so exceedingly delicate,
that even the water added for their examination speedily
renders them a confused mass, in which little is discernible
save certain large Raphidian cells. So essential has it ap-
peared to have the flowers freshly gathered, that I have felt
obliged to reject some observations made on withered petals,
lest wrinkling of the cell-wall might have been thus induced,
and erroneous opinions formed—the serious nature of which
will be seen as we advance. Descriptions of appearances
brought into view in petals dried, mounted in Canada balsam,
blistered by heat (I had almost said tortured to produce false
appearances), cannot therefore but be viewed with distrust.
Were anything to be gained by it, it would not be difficult
to explain the nature of the errors induced by such modes of
examination.

Having then procured perfectly fresh flowers, a petal was
detached, and bent backwards so as to expose the outline of
the layer of cells forming the inner surface; another petal,
bent inwards upon itself, gave the outline of the external
surface ; the margin was next examined, and, finally, por-
tions torn up with needles. Glycerine was found very useful
in rendering the structures distinct, and I may mention also
that it preserves most petals in a highly satisfactory manner.

In the great majority of the plants examined, which
amounted to some hundreds, when a profile view is thus
obtained, it will be found that the cuticle is not uniformly
level, but the cells composing it are mostly elevated towards
the centre, more or less above the general surface. Such

—

WEST, ON PETALS OF FLOWERS. 23

elevation is almost invariably greatest on the imner surface
of the petals, and the descriptions here given, with only one
exception, apply to such. Between the cuticles the tissue is
generally stellate, in one or several layers.

These elevations may be formed, either by general con-
vexity of the outer cell-wall (Ranunculus aquatilis, fig. 1—iris,
fig. 2), or dome-shaped (ten-week stock, fig. 3), or a partial
elevation of the centre (featherfew, Pyrethrum parthenium,
fig. 4), mammilate (geranium, fig. 5—orchis, fig. 6), awl-
shaped, acute (sweet william, fig. 7—mimulus, calceolaria,
&e.) On the outer surface of the tubular corolla of
Comfrey, Symphytum officinale (fig. 8), they are very long,
and intermixed with undoubted hairs. In the Cruciate they
appear to be the coloured petalline hairs of Balfour. The
most rudimentary condition of these elevations is that of a
minute papilla, rising abruptly from the centre of every cell,
or nearly so; a good example of this is seen in Gladiolus
(fig. 9). That they are truly hairs in a rudimentary con-
dition, the examination of an extensive series of instances
will leave no doubt. On the lip of a brilliant little blue
lobelia every gradation may be met with, from the slightest
convexity of the cells to true hairs ;4, m. in length, and
equally so on the same part in Antirrhinum majus. 'To these
mammillate protuberances has been attributed the velvety
appearance of the surface of petals; they form truly the
“‘pile,”’ so to say, “of the velvet.” It seems probable, also,
that from their convex form, they may act as lenses in
magnifying the brillianecy of the coloured chlorophyll.
Another way in which the richness of the hues of flowers is
enhanced would, perhaps, scarcely suggest itself readily to
any but an artist. I allude to the separation of the colour
into regularly arranged symmetrical spots by the colourless
cell-walls, thus obtaining what is technically called “ air ;”
an effect that is rudely imitated by artists, according to the
substance on which they work and the facilities which their
materials may afford for its production. That this idea is
not fanciful, may be readily seen by comparing an imitation

oe
Arie
F
Ig &
Sap Wes.
ple,
CP
8.905%:
BASS
So Bait
KO
Cyory 2
CI FEL

ez.
;
2S
4,
. he rr
x
g!
BD
2,
p,
©.
Qe.

on wood of the stippling of the miniature painter (fig. 1),
who requires thus to produce the utmost degree of bright-
ness which his colours will afford with fig. 2, a diagrammatic

24 WEST, ON PETALS OF FLOWERS.

representation of part of the petal of the scarlet geranium,
under a very low power. That the radiating lines seen not
unfrequently on the cell-wall in this situation can have any
appreciable effect in producing the brilliancy of flowers, as
maintained by Schleiden, seems, however, more than
doubtful.

These papillz, or “ mammiliform protuberances,” may be
either marked with lines or dots, or smooth and destitute of
both. Good examples of these lines are presented by the
petals of geranium (fig. 5), and pelargonium (fig. 14).
When the outer cell-wall is papillate, they assume a radiate
arrangement, which is seldom distinctly perceptible in the
cells of petals, the surface of which is pla. These lines
have been considered by Schleiden and Carpenter to be
probably due to secondary deposit, and such was, up to a
recent period, my own belief. In examining the petal of
ladies’ bedstraw (Galiwm verum, fig. 10), [found an interesting
condition of the parts. The cells here are not elevated above
the general surface into papille, but are covered with large,
raised, tubercle-like spots, arranged with considerable regu-
larity, of a glassy transparency, and showing section dis-
tinctly. Some idea of their appearance may be formed by
imagining a plate of glass, whilst still soft, to be pressed out
in spots by a small blunt tool, and cooling rapidly, to retain
the impressions thus caused, which, by turning the glass over,
would become elevations on the now uppermost surface.
Similar tuberculoid dots are found on the lobelia before-
mentioned on Antirrhinum majus, &c. Schleiden long
ago described “ tubercles”’ studding hairs from the fornix of
Anchusa Italica, and figures them as if formed by layers of
successive deposit m some cases. In this he has been
followed by other authors; and Quekett represents some of
them detached, as if rubbed off, which, were they really
tubercles, might occur. At the time when this Anchusa was
in flower, I was unfortunately too much engaged to be able
to hunt after it; but hairs presenting external “elevations are
not uncommon.

The example of Galium just mentioned showed con-
clusively, however, that tubercle-like elevations might be

ee oe aa aS ee
Fig. 3 Fig. 4.

present on the walls of cells, or their prolongations, without
the presence of external secondary deposit. The cell-wall is
pretty thick, firm, of exquisite transparency, and can be

WEST, ON PETALS OF FLOWERS. 23

clearly traced as forming the tuberculoid elevation. A
diagram (fig. 3) may serve to render my meaning clear. If
the elevations were due to secondary deposit, we should see
distinctly, as in the imaginary instance (fig. 4), the cell-wall
continuous, and supporting an extraneous substance.

Having satisfied myself, from this instance, that on the
outer surface of vegetable cells, protuberances and hairs were
not necessarily owing to external secondary deposit, I made
very numerous examinations into analogous cases, the results
of which have led me to believe that the views now held on
this subject will require much modification to render them
consonant with truth. I have met with no certain example
of such, though one or two instances have occurred to me in
which there might be a degree of doubt, from the top of the
tuberculoid elevation being somewhat thicker than the sides ;
in Galium mollugo it is so. But we need not hence assume
that this is from secondary deposit, for it is certain that the
cuticular cell-walls are not of equal thickness in all parts,
and such an appearance may be easily explained without such
an hypothesis.

Hairs of much value for the purposes of our present inquiry
occur in the throat of the pansy (Viola tricolor and varieties
of V. lutea, fig. 11). They are large (35th im. long), knobbed all
over ; these knobs, clearly produced by outward bulging of
the cell-wall, are themselves irregular with lesser warty
prominences, and towards the attached end of the hairs they
subside into interrupted subspiral lines, equally due to
folding. A sectional view of hairs from the throat of verbena
(fig. 12) and petal of the musk-plant (fig. 13) shows that the
dotted markings they possess arise in the same way.

The radiating lines on the petals of geranium, &c., are
likewise caused by corrugation. In petals removed from the
scarlet geranium whilst the bud is still very immature, neither
the papille, the radiating lines, nor certain so-called
“hairs” arranged round the base of the papill, are present.
But on examining petals from flowers advanced to about
twenty-four hours from the period of opening, these are all
found pretty well developed. Being still in a soft condition,
the action of nitric acid diluted may be watched under -the
microscope, causing evolution of the cell-walls and disappear-
ance of the radiating limes or folds, with consequent
appreciable increase in size of the papilla out of which they
were formed. The petal of the larkspur shows the same
facts equally well. When the eye is thoroughly familiarised
with the objects, the optical appearances alone are almost
sufficient to enable a confident opinion to be formed.

VOL. VII. D

26 WEST, ON PETALS OF FLOWERS.

Round the margin of the cuticular petalline cells of pelar-
gonium (fig. 14), geranium, in all its species, so far as I have
had the means of ascertaining (fig. 5), periwinkle, Vinca
major (fig. 15), nemophila, aiid others, are little dentate pro-
cesses, appearing, when viewed from above, as if pointing
inwards towards the centre of the cell to which they belong.
Seen in profile, it becomes evident that they do not project
freely into the cavity of the cell, nor outwardly, but are
indeed in close apposition with the cell-wall. These are
really pats of internal secondary deposit, as is proved by
watching the progress of their development and the action of
nitric acid. Such little pats are common at the most pro-
jecting part of the curves of sinuous petalline cells; the
curves sometimes become angular, and this appearance is
much increased by the deposit. In the clove-pink (fig. 16)
this secondary deposit is laid down more irregularly; in the
petals of the white poppy (Papaver somniferum, fig. 17) and
St. John’s wort (Hypericum) they form an imperfect spiral.
Another case of what will be probably found to be due to the
same cause is met with in some petals just within the point of
the papilla; this is the case in Orchis maculata, and in Vinca
major (fig. 15).

It would be interesting to ascertain if, when papille occur,
we may expect to find them in other species of the same
genus, and in allied genera; also to what degree they retain
similar forms and markings. My observations are not suffi-
ciently numerous to found safe generalizations upon, but
they appear to favour the idea that such may be the case.

In conclusion, it may be well briefly to recapitulate the
propositions here sought to be established. They are—

lst. The prolongation of the outer cell-wall of the cuticle
of petals into mammillary protuberances as a usual con-
dition; such elevations being, with rare exceptions, most
marked on the inner surface, and being hairs in a more or
less rudimentary condition.

2d. That the markings on the parts here named (which
may be divided into two kinds, lines and dots, though
examples of an intermediate nature occur) are both caused by
corrugation of the cell-wall, and not by external secondary
deposit upon it.

Note.—The dots here spoken of on some petalline cells and many vege-
table hairs have a special interest, from the light they throw on the trae
nature of the markings of the Diatomacex. In each we have minute spots,
but in the first named they are above, in the latter below the general level of
the surface. It is as unphilosopiical then to apply the term “ cellules” to

the markings of a diatom, as it would be to give it to the tuberculoid dots
in question.

a
“tu

On the OrticaL Powers of the Microscope.
By P. G. Rytanps, Esq.

Tue period has not yet arrived when even all those who
employ the microscope methodically, as a means of scientific
investigation, possess an intelligent comprehension of the
principles on which it is constructed and the nature of its
powers as an optical instrument. There is a large region
beyond mere manipulation, into which few apparently care to
enter. The writers of our introductory treatises have been
curiously imitative in dealing with this portion of their duty.
They indulge us with nearly the same very elementary
diagrams, refer us to Ross’s capital article “ Microscope,” in
the ‘ Penny Cyclopedia,’ and then, with here and there only
a trifling exception, leave the matter pretty much as they
found it. Surely the time has arrived which calls for more
than this ; when an optical treatise on the microscope, worthy
of the name, is not only desired by the few but required for
the many. In the meantime, until this boon be granted,
your pages will continue to do good service by dealing with
these matters, and, as heretofore, in such a manner as to
secure to your readers a large store of information.

I had hoped that some more able hand than mine would
have undertaken the subject on which I now propose to occupy
a portion of your space; but it has not been so, and I there-
fore offer the following remarks on the optical powers of these
instruments to your readers, without further introduction.

The first power which I shall mention requires little
remark. It is the one which has attracted the greatest share
of attention, from being that which constitutes the most
prominent characteristic of the microscope. I mean magni-
fying power. For our present purpose it is sufficient to
remind the reader that magnifying power has to do with size,
and size only. It expresses simply the dimensions of the
enlarged image presented to the eye of observers, as compared
with the size of the natural object when viewed at the adopted
standard distance, ten inches, from the eye. Or, in other
words, it may be said to express the magnitude of the angle
subtended by the enlarged image, at the eye, as compared
with that subtended by the object itself under the circum-
stances named.

The second, or penetrating power, is a subject which
cannot be dismissed so easily. The origin of the term will
be found in the ‘ Phil. Trans.’ for 1800, in an article by Sir
William Herschel, entitled, “On the Power of Penetrating

28 RYLANDS, ON THE MICROSCOPE.

into Space possessed by Telescopes.’ In that article we are
told that when, owing to the darkness, a distant church-
steeple was invisible, a certain telescope described showed the
time by the clock upon it very clearly. This, adds Sir
William, was not owing to magnifymg power alone, for the
steeple could not be discerned by the naked eye.

Following out the suggestions of this incident in a truly
philosophic spirit, the author has given us, in the article
referred to, all that is required to apply the term correctly to
the microscope.

Unless I am mistaken, the first use of the word in con-
nexion with the microscope occurs in the ‘ Microscopic
Cabinet.’ Judging from the manner in which it is there
employed, we should perhaps define it as synonymous with
angular aperture. Most persons, I fancy, were at a loss to
see the connexion between the name and the thing signified,
for, while some few writers were content to adopt the term
with the explanation given, others, considering it an entire
misnomer, began to speak of angle of aperture, and have
since defined ‘“‘penetrating power” to mean superior definition,
thickness of field, &c. This has naturally led to confusion,
and that not amongst those only who make small pretensions.
Dr. Carpenter, in his ‘ Manual,’ tells us that the penetrating
power of an olject-glass “depends upon the degree of dis-
tinctness with which parts of the object that are a little out
of focus can be discerned,” or, in other words, longitudinal
focal range or thickness of field. The editors of the ‘ Micro-
graphic Dictionary’ mention “two distinct kinds of pene-
trating power,” one the same as defining power, and the other
angular aperture, combined with oblique illumination. They
propose that the term should be laid aside as tending to con-
fusion! I think it may be shown that the confusion is not
altogether attributable to the term, and that the whole
difficulty not only admits of an easy solution, but that the
subject is sufficiently important to warrant a careful investi-
gation.

The authors of the ‘ Microscopic Cabinet’ had in their
minds, there is no doubt, the true origin and meaning of the
term. They erred in not giving a sufficient explanation.
They borrowed it from the telescope, and, seeing that the
telescope and the microscope are essentially the same instru-
ment, but modified to adapt them to different purposes, the
use they made of it was perfectly justifiable; at the same
time it must plainly be used to mean the same thing in both
cases. Sir William Herschel has shown, in the article
already referred to, that the words penetrating power have a

RYLANDS, ON THE MICROSCOPE. 29

definite meaning, and that the amount of this power possessed
by a telescope can be obtained by calculation. This must be
true of a microscope also. This power must not be confused
with angular aperture, which has reference to the objective
alone; neither has it any connexion with either definition or
thickness of field. In one word, as magnifying power
expresses the angle subtended by an object or image at the
eye of the observer, so penetrating power is the measure of
the angle subtended by the eye at the object, or the equivalent
of that angle in the case of telescopic or microscopic vision.
The one is the measure of size, the other of brightness. This
latter, however, must not be confused with “illumination.”
The one power is neither less important nor less essential to
distinct vision than the other. There required little magni-
fying power, and there was no illumination, in the case of the
church-steeple, still the hour could be read on the dial. It is
the power by which this was accomplished that we have to
consider.*

Referring those who wish to investigate this matter fully
to the paper in the ‘ Phil. Trans.,’ I shall content myself with
making use of such portions of Sir W. Herschel’s formula as
is sufficient for our present purpose. This may be given as
follows :

Putting P for the penetrating power of a refracting tele-

scope,

« for the proportion of light which remains for
purposes of vision after passing through a
single lens,

nm for the number of lenses in the instrument,

A for the available diameter of the object-glass,

and a for the diameter of the pupil of the eye; we

have—
pa Vor

a

—

By applying this to the microscope, we shall obtain that
which alone can be correctly called “ penetrating power.”
We shall see clearly in what the value of increased angular
aperture really consists, and I think we shall come to the
conclusion that the term under consideration represents some-
thing sufficiently important to prevent its being laid aside on
account of any foregone carelessness or confusion.

The great distinction between the telescope and the micro-

* We are not told what magnifying power was employed in viewing the
church-steeple, but I gathered from something in the paper that the pene-
trating power of the telescope was about forty times that of natural vision.

30 RYLANDS, ON THE MICROSCOPE.

scope exists im the fact that while the former, practically
speaking, is suited to receive parallel rays from a distant
object, the latter has to deal with rays which are sensibly
divergent from a closely approximate pot. On this account
the formula will require some modification.

In natural vision the rays emergent from any point of an
object, which are employed for the purposes of vision, form a
cone having the area of the pupil of the eye for its base.
When the microscope is applied, the available aperture of its
anterior lens takes the place of the pupil, and a cone of very
different proportions is substituted. It is on the relative
magnitude of the angles at the vertices of these cones—
allowance being made in the latter case for the light lost im
its passage through the instrument —that penetrating power
depends. Thus the connexion with angular aperture is seen
to be sufficiently close to form some excuse, perhaps, for one
definition which has been given.

It is only necessary to premise further that the formula
may be stated in a rather more convenient form, thus :

Ale,

If A be now made to stand for half the angle of aperture
of an objective, and a half the angle subtended by the pupil
of the eye at ten inches, instead of the diameters of these
apertures as before, the formula applicable to microscopes
will be—

tan A

tan a

1s

Further, if we are content to adopt 0°2 inch as the mean
or standard diameter of the pupil, which is sufficiently exact
for general purposes, the equation becomes—

P= 100 tan A 4/3" *

* From two series of measurements of the diameter of the pupil I ob-
tained the following results :

In full daylight, near the window of a well-lighted room, 0:15 in. ; at the
most convenient distance for distinct vision from a Highley’s argand gas
lamp, 0°25 in.; the mean of the whole being 0°2 in.

As simplicity is a great matter in such calculations as the one now under
notice, it may be worth while to remark, that if the value of 2” for the in-
struments of our best English makers should be found to be sufficiently con-
stant, which is quite probable, the expression, so far as they are concerned,
may be reduced to a single operation, and the value of P taken almost at
sight from a table of tangents.

The angle of aperture of an objective should be obtained by Mr. Lister’s
method (‘ Phil. Trans.,’ vol. exxi; see also Quekett, p. 464), separately with
each eye-piece and length of draw-tube.

P=

RYLANDS, ON THE MICROSCOPE. 31

1 shall not stay here to point out the advantages of obtain-
ing the amount of penetrating power in the manner de-
scribed ; this, and all that need be said further on the sub-
ject, will, I trust, be sufficiently clear from what follows.

The third power—the visual power of microscopes—is one
which has been so rarely recognised as distinct, that probably
even the name will be new to most of your readers.

It is well known that the extent to which vision is aided
by a telescope (for we must be mdebted once more to that
instrument) is very rarely expressed by its magnifying power ;
that two instruments, equal in both magnifying and defining
power, may differ widely in their visual power; and as in the
telescope, so in the microscope, for they are essentially the
same in principle.

Perhaps an example will most easily explain what is meant
by visual power, and its connexion with the two already
described.

Some years ago, when my attention was first directed to
this subject, I made the following experiment with a common
marine “day and night glass.’ Having extemporised a
““pancratic tube,” by which the power of the instrument was
increased to 43, I directed it to a sign-board at the distance
of 489 yards. This object had the double advantage of being
readily approachable in a direct lune, and of having upon it
letters of various sizes, so that it exhibited several degrees of
legibility. Its distance, too, was ascertainable with sufficient
exactness. Having impressed upon my mind the appearance
of the board as presented by the telescope, I approached it
until it was as legible and looked the same to the naked eye.
From the peculiarity of the object, this point was ascertained
at once within the limit of three or four feet. According to
the popular idea, I ought to have been at one forty-third the
original distance, the power of the glass being 48. Instead
of this, however, I had passed over only fifteen sixteenths of
the space; that is, the visual power was only 16, although
the magnifying power was 43. This was not quite what L
expected, but the examination was not long delayed.

In order that an object shall be seen through a telescope
(or a microscope) as when viewed at one forty-third the
distance, it is necessary, not only that the angle subtended
by it at the eye—the magnifying power—but also the angle
subtended by the eye at the object—the penetrating power—
shall be increased forty-three-fold. When this is the case,
the visual power will be forty-three also. If we approach an
object bodily, these angles naturally increase in the same
proportion, but it is not so where optical instruments are

82 RYLANDS, ON THE MICROSCOPE.

used. Still, visual power must be a compound of the other
two, and calling the three powers M, P, and V respectively,
from their initials, we ought to have, im all cases—

V=vVMP

To test the experiment just related by this, the value of
P having been carefully determined at the time, we find
M = 43, P = 6, and

V=V43 x 6= 16:06

The value of V, as obtained by measurement, was 16:3,
which is as near as could be expected under the circum-
stances, although every precaution was taken to ensure cor-
rectness. Visual power is, therefore, essentially the power
of a telescope.

IT need not extend this already lengthy article to show
how entirely all this is applicable to the microscope also.
I do not say that the variation will be as great in that
instrument as in the telescope, for the construction is not
only more uniform,* but the peculiarities of microscopic
vision confine the matter in one direction, at least within
narrower limits; but I do say that the time is long gone by
for the distinctions I have pointed out to be neglected, or for
us to have important and valuable terms drifting to and fro
im our literature without any fixed meaning, threatened with
expulsion by those in high quarters, and defined by each
succeeding writer according as it seems good in his own eyes.
Neither should we suffer ourselves to be deceived by large
numbers, expressing amplification, it may be, but failing to
afford us their promised aid in our search after natural truth.
Fortunately the discoveries of the past quarter of a century
have led us in the right direction; what we seem now to
require 1s simply a correct determination of the value of x in
the foregoing formule; we shall then be able, with very little
trouble, to estimate the visual powers of our instruments,
and shall have our efforts systematically directed to the in-
crease and perfection of that upon which their value mainly
depends.

* This is more especially true of the instruments by our best English
makers. The relative value of others will probably appear in a strong light
when they are submitted to the test of visual power. The following ap-
proximate estimates, obtained from a French instrument, will not be with-
out interest :

1st combination, M = 400, V (highest estimate) 145.
2d AS M = 540, V, cannot exceed 905.
3d is M = 870, V, does not reach 320.

33

OBsERVATIONS on the DrveLopmMentT of some parts of the
SKELETON of Fisues. By Tuomas H. Huxtey, F.R.S.,
Professor of Natural History, Government School of
Mines.

Tue following observations were made principally upon
the Stickleback (Gasterosteus leiurus) i the summer of the
present year. Some of them were briefly alluded to in my
Croonian lecture “On the Theory of the Vertebrate Skull,”
delivered before the Royal Society on the 17th of June
last, and will be more fully treated of hereafter; the rest
have not yet been published.

1. On the development of the tail in Teleostean fishes.

The fact that at a certain period in the embryonic life of
Teleostean fishes, the extremity of the chorda dorsalis or noto-
chord is bent upwards, was discovered and its importance
indicated by K. E. Von Bar, in his ‘ Untersuchungen iiber
die Entwickelungs-geschichte der Fische’ (1835), where
he remarks, respecting the embryos of Cyprinus blicca—

“‘T was greatly surprised to observe, that from the fifth
day onwards, the posterior extremity of the vertebral column
bends upwards, so that the caudal fin which now begins to be
developed is not disposed symmetrically, but lies more below
the extremity of the vertebral column; a relation which is
permanent in the cartilaginous fishes.” (p. 6.)

The conception of a relation between the embryonic con-
dition of the tail in Teleostean fish and the adult state of
the same organ in Ganoidet and Elasmobranchii, thus put
forth, received a further development from Professor Vogt, the
able author of the ‘ Embryologie des Salmones’ (1842), which
forms a part of M. Agassiz’s ‘ Poissons d’Eau douce.’ At
p. 256 of this excellent monograph, Vogt says—

“The curvature of the extremity of the chorda dorsalis,
which begins to be apparent in the Coregonus a short time
before it is hatched, and attains its greatest amount about
six weeks later, is another peculiarity of the embryos which
deserves to be taken into consideration, because it subse-
quently disappears, and exists in adult fishes only in some
genera of existing Ganoids and Placoids. These relations have
not escaped the notice of observers, and M. Von Bar par-
ticularly expresses himself as follows.”

Vogt here gives the preceding citation from Von Bar,
and then continues :

3k HUXLEY, ON THE SKELETON OF FISHES.

“This peculiarity, together with many other features
characteristic of embryos, has naturally led me to examine
into the relations which exist between these modifications
and the characters which distinguish the fossil fishes of dif-
ferent geological epochs. . . It is a fact well
known to all anatomists, that the vertebral column of carti-
laginous fishes does not terminate in the same way as that
afi osseous fishes; in the former the bodies of the vertebrze
become successively smaller from before backwards, and
incline upwards more or less towards the end of the tail, so
that the part of the vertebral column which carries the rays
of the caudal fin forms a very open angle with the longitudi-
nal axis of the trunk. A very peculiar form of the caudal
fin results from this disposition : instead of being symmetri-
cally bifurcated, it is simply bilobed, in such a manner that
the superior lobe, situated, like the ‘inferior, under the pro-
longation of the vertebral column, extends further back than
the latter, which is produced only by an elongation of the
anterior rays of this same inferior side of the vertebra. It
results from this, that the caudal fin of the Plagiostomes has,
properly speaking, no rays* inserted in the upper face of its
vertebre.

“In osseous fishes, on the other hand, the vertebral column
terminates behind in a great expansion, whose superior
and inferior apophyses are strongly dilated, so as to form a
large vertical plate, whose posterior edge is symmetrically
truncated, so as to present. an equal surface of attachment for
the caudal fin-rays above and below the prolongation of the
vertebral column. This caudal piece may be regarded as
resulting from many vertebre soldered together, or else as a
simple dilated vertebra carrying many yertical apophyses.
The chorda dorsalis is continued in its interior, and is also a
little bent upwards, so that, neglecting the osseous vertebral
rings which surround the chord, it terminates as in the
Plagiostomes. But the apophyses of this caudal piece are
always disposed in such a way that those of the superior face
carry the upper half of the rays of the caudal fin, and the
inferior apophyses the inferior rays; and the result is a very
regular disposition of the caudal fin, which is divided imto
two equal lobes, whose rays are inserted like a fan upon the
spinous processes of the last vertebra, and arranged in such a
manner that the rays of the upper lobe correspond to the
upper apophyses, and those of the lower lobe to the lower
apophyses. The slight differences of form and size which

* This statement, however, is incorrect, as Miller had long before shown.
(Te He

HUXLEY, ON THE SKELETON OF FISHES. isi)

are sometimes remarked between the two lobes never affect
the disposition of the rays; for even when the caudal fin is
cut square or rounded, it is not less invariably divided into
two nearly equal parts, the superior of which is inserted on
to the superior apophysis of the last vertebra. We may,
then, regard this disposition as constant among osseous
fishes, despite the slight inequality which is sometimes ob-
served between the superior and inferior apophyses, and not-
withstanding the curvature of the chorda at its posterior
extremity.”

M. Vogt then goes on to point out that since, according to
M. Agassiz’s researches, all fossil fishes before the Jurassic
epoch had inequilobed or heterocercal tails, while those with
equilobed or homocercal tails only appeared subsequently,
there is a parallelism in this respect between the several
stages of the embryo of such a (Cycloid) fish as a Coregonus,
and the groups of fishes which have at successive epochs
peopled the waters of the globe. In his ‘ Recherches sur les
Poissons fossiles,’ vol. 11, p. 102, the same doctrine is thus
concisely expressed by M. Agassiz :

“© On the other hand, there is neither in the actual creation
nor in anterior epochs, any adult fish belonging to these two
last orders (Ctenoids and Cycloids) which has the vertebral
column bent up, and the caudal fin inserted below it; whilst
this arrangement is characteristic of embryos in a certain
period of their existence. There is then, as*we have said
above, a certain analogy, or rather a parallelism, to be es-
tablished between the embryological development of the
Cycloids and Ctenoids, and the genetic or paleontological
development of the whole class.”

Professor Owen (‘ Lectures on Fishes,’ 1846) describes the
caudal fin of the ordinary osseous fishes thus :

“The framework of the caudal fin is composed of the
same intercalary and dermal spines superadded to the proper
neural and hemal spines of those caudal vertebree which
have coalesced and been shortened by absorption, in the
progress of embryonic development, to form the base of the
terminal fin.” (p. 67.)

It would be very desirable to know in what fish Professor
Owen observed this singular process of coalescence and
absorption. So definite a statement must rest on some-
thing more than mere supposition, .and yet it is entirely
unsupported by any hitherto published observations with
which I am acquainted, and is, as will be seen below,
directly opposed by my own.

In the excellent ‘Lehrbuch der Vergeichenden Anatomie,’

36 HUXLEY, ON THE SKELETON OF FISHES.

by Von Siebold and Stannius (1846), the latter (‘ Wirbel-
thiere,’ p. 10) considers the vertical caudal plate to be -
produced by the coalescence of the superior and inferior
arches, interhzemal and interneural bones “ of the posterior
caudal vertebra or of many of the caudal vertebre ;” and in
a note it is added, that the commencement of the process
may be clearly traced in the pike.

Avaluable paper published bythe late eminent ichthyologist,
Heckel, in the ‘ Sitzungs-berichte der Kaiserlichen Akademie
der Wissenschaften’ for 1850 (p. 143 et seq.), contained the
first accurate and comprehensive account of the structure of
the piscine tail, and threw quite a new light on the general
doctrine of the relation between ancient and modern fishes.

“The few now-living successors of the bony Ganoids with
complete vertebra, which first appeared in the Jurassic
period—our Lepidosteus, Polypterus, and probably also Amria
(the latter of which I have had no opportunity of examining)
—still have quite imperfect terminal vertebre, behind which
a part of the chorda persists in a perfectly unossified state.
At the same time these terminal vertebree appear to be de-
veloped in quite a different way from those of ordinary
Teleosteans, for the arrested commencements of the posterior
caudal vertebre, or their first centres of ossification, appear,
not as in the latter, above and below at the base of already
formed spinous processes, but at the sides of the chorda,
before either spinous processes or vertebral arches are de-
veloped. They become thickened anteriorly, and penetrate
like wedges towards the axis of the chorda. Indeed, it would
seem, from the fact that different imdividuals of these fishes,
without distinction of size, present a considerable variation
in the number of their terminal vertebrae (which may be
even perfectly developed) as if they constantly added new
vertebree, whereby the end of the-vertebral column—that 1s to
say, the still naked chorda—must gradually, if not perfectly,
be converted into ossified bodies of vertebree. .... .

“Another group of fishes, or rather of the now-living
Teleosiei (whose origin is wrongly placed in the Cretaceous
period, since it certainly took place much earlier, in the
Jurassic epoch), also possess an imperfect vertebral column.
No inconsiderable portion of the end of the chorda remains
without developing vertebree throughout the whole life of
the fish, and becomes hidden under a roof-like arrangement
of peculiar bones, which, supported upon the penultimate
vertebral bones and projecting backwards beyond them, and
seeming to be mere upper spinous processes, or ray bearers,
unite with the broad inferior spmous processes which haye

HUXLEY, ON THE SKELETON OF FISHES. 37

coalesced so as to form a vertical fan-like plate. In these,
as well as in the bony Ganoids mentioned above, the canal
for the spinal cord, so soon as the vertebrz cease, passes
back above the undivided chorda, and both are invested by a
common case of solid cartilage, which takes the form of a
long cone. It is a further peculiarity of the Teleostei in
question, whose caudal rays, with the exception of the upper
short ones (‘stiitzen strahlen’), are altogether beneath the
vertebral column, that their terminal vertebra is biconcave.
The vertebral arches unite in pairs, and form by their proper
elongation a double spinous process. In one part of these
fishes (whose ancestors made their appearance in the Jurassic
epoch) the arches are wedged into pits in the bodies of the
vertebre (as in Thryssops, Tharsis, Leptolepis, Chirocentrites,
Elops, Butirinus, Salmo, Coregonus, Saurus, Sudis, Esoz,
Umbra). In the others, which only appear subsequently in
the Chalk, the vertebral arches, and even the roof-like bones,
are inseparably united with the bodies of the vertebre
(Clupeide, Cyprinide, Cobitis).

“In the great multitude of the remaining Teleostei, the
end of the vertebral column is far more developed. The
chorda is ossified to its extreme end, or crystallized into ver-
tebree, the last of which, therefore, possesses. only a single
funnel-shaped cavity, containing the end of the chorda, and
turned forwards. But in the greater number of these
Teleostei, whose ancestors made their appearance contempo-
raneously with the second division of the first-mentioned
roof-tailed fish in the Chalk, the spimal canal alone is pro-
longed behind the last vertebral arches, as a bivalve or
tubular bony sheath, between the fin-rays. These are the
Percide, Scorpenide, Scienide, Chromide, Sparide, Squami-
pennes, Teuthide, Labyrinthiformes, Scombrede, Pecilia,
Characine, Mormyride, Siluroidet, and others. The smaller
number began to exist an epoch later, with the tertiary forma-
tions, and in these only does the spinal marrow end at the
same time with the chorda in the last vertebral body, or at
least in an inseparable process of it (Labride, Gadide, Blen-
nide, Gobiide, Pediculoti, Pleuronectide, Lophobranchii,
Plectognathi, and others).”

I have omitted Heckel’s account of the vertebral column
of the Pycnodonts which precedes the long and important
extract here given, as less immediately germane to the present
subject. Suffice it to say, that he admits altogether three
modes of termination of the chorda dorsalis: 1. The end is
naked or unprotected by any ossification, as in Palzeozoic
Fishes and existing Ganoidei. 2. Its unossified end is pro-

38 HUXLEY, ON THE SKELETON OF FISHES.

tected to a greater or less extent by lateral roof-like plates, |
as in the Salmonide ; these Heckel calls Steguri. 3. The
end of the chorda is enclosed within the anterior cavity of the
body of the terminal vertebra, as in the Percide, &c.

I shall bring forward grounds for believing that Heckel is
mistaken as to this third mode of termination, and that in
these fishes the end of the chorda really extends far beyond
the anterior cavity of the last vertebra.

In 1854, Stannius published (as a part of the new edition
of the ‘ Handbuch’) his ‘Zootomie der Fische,’ beyond all
comparison the best and most exhaustive work on the sub-
ject which has yet appeared. The structure of the fish’s
tail is discussed at p. 29, but very unaccountably all mention
of Heckel’s researches is omitted. In the Blennide, Ophio-
dini, Tenioide, Murenoide, Fistularie, the last caudal ver-
tebra is said to end ina slight point. In Cyclopterus, Calli-
onymus, the Pleuronectide, and Plectognathi, “the end of the
last vertebra becomes flattened and slender, and is prolonged
into a vertical broad plate, consisting of two quite symme-
trical halves, an upper and an under.”

A more detailed (but otherwise essentially similar) account
to that of Heckel, of the tail of the Salmonide, is next given,
and the like structure is said to obtain throughout life in the
Ganoidei, in Esox, Hyodon, &ec., while it is transitory in
Cyprinide, Characine, and others.

In conclusion, Stannius points out that ‘ many fish which
pass for homocercal, show unmistakeable traces of original
heterocercality.”

Having verified Stannius’s account of the structure of the
caudal extremity in the salmon, but seeing no reason to
doubt—what was generally admitted—that other Teleostean
fish were truly homocercal, I pointed out, in 1855,* that the
foundation of the doctrine of Vogt and Agassiz was thereby
destroyed. For Vogt’s observations were made on a sal-
monoid fish, and a right comprehension of the structure of
the tail in such fishes showed, that so far from the heterocer-
eal tail of the embryo becoming homocercal in the adult, the
tail of the latter was extremely heterocercal, far more so than
that of many cartilaginous fishes. In fact, all that Vogt had
really shown was, that the primitively homocercal tail of the
embryo becomes gradually more and more heterocercal ; and
he and others had been misled by the apparent homocercality
of the adult fish imto supposing that the heterocercality be-
came lost again, whereas, in point of fact, it was only
disguised.

* Friday evening meetings of the Royal Institution.

HUXLEY, ON THE SKELETON OF FISHES. 39

Consequently, Vogt’s observations did not prove in the
least that a truly homocercal fish ever passed through a
heterocercal state; and as no observations respecting the
development of the tail in what were supposed to be truly
homocercal fish were extant, the doctrine that heterocercality
precedes homocercality in embryonic life, was clearly not
proven. On the other hand, until the development of some
admitted homocercal fish had been examined, it was not
disproved.

Having procured a number of very young sticklebacks
and eels, which would assuredly be admitted to be true
homocercal Teleostei, if such things exist at all, I gladly
availed myself of the opportunity of examining into this
point. I was not a little surprised to discover, not only that
these fishes are heterocercal in the embryonic state, but that
they are perfectly heterocereal in the adult condition, their
apparent homocercality being, as in the case of the salmon
and its allies, a mere disguised heterocercality.

In a Stickleback +;ths of an inch long (fig. 1), I found
the gradually tapering extremity of the notochord (ce) bent
upwards at a considerable angle with the axis of the body,
and terminating close to the superior rounded corner of the
caudal fin. In the greater part of its extent it was enclosed
neither in cartilage nor in bone—though bony rings, the
rudiments of the centra of the vertebre, were developed in
the wall of the notochord throughout the rest of the body.

The last of these rings (4) lay just where the notochord
began to bend up. It was slightly longer than the bony
ring which preceded it (a), and instead of having its posterior
margin parallel with the anterior, it sloped from above,
downwards and backwards. Two short osseous plates (e),
attached to the anterior part of the inferior surface of the
penultimate ring, or rudimentary vertebral centrum, passed
downwards and a little backwards, and abutted against a
slender elongated mass of cartilage (gy). Similar cartilagi-
nous bodies occupy the same relation to corresponding plates
of bone in the anterior vertebre in the region of the anal
fin; and it is here seen, that while the bony plates coalesce
and form the inferior arches of the caudal vertebree, the car-
tilaginous elements at their extremities become the inter-
hemal bones. The cartilage connected with the inferior
arch of the penultimate centrum is therefore an “inter-
hemal” cartilage. The anterior part of the inferior surface
of the terminal ossification likewise has its osseous inferior
arch (f), but the direction of this is nearly vertical, and
though it is connected below with an element (4) which

40 HUXLEY, ON THE SKELETON OF FISHES.

corresponds in position with the interhemal cartilage, this
cartilage is five or six times as large, and constitutes a broad
vertical plate, longer than it is deep, and having its longest
axis inclined downwards and backwards. Its superior and
inferior margins are slightly excavated, the posterior is con-
vex, the anterior deeply notched, so as to be divided into two
processes, the anterior of which abuts against the inferior
arch of the vertebra, while the posterior is applied against
the posterior moiety of its under surface. On each side of
the posterior convex edge of the cartilage (which they a little
overlap), I found five slender osseous styles (4), the rudi-
ments of the inferior caudal fin-rays.

Immediately behind and above this anterior hypural apo-
physis (as it may be termed) is another (’) very much smaller,
vertical cartilaginous plate, which may be called the poste-
rior hypural apophysis, having nearly the form of a right-
angled triangle, and closely applied by its hypothenuse to the
under surface of about the anterior two fifths of the free
portion of the chorda. On each side of the posterior edge of
this cartilage are three fin-rays (4), similar to those already
described, so that in the caudal fin im this stage there are
altogether eight double rays, and all these are imserted, not
only below the notochord, but far in front of its termination.

No neural arch is as yet developed from the terminal
osseous ring.

A great change had taken place in the tail of an embryo
Gasterosteus, =;ths of an inch long (fig. 2). All the pre-
ceding parts, however, were readily recognisable, notwith-
standing their modifications.

The penultimate centrum had become much longer in pro-
proportion to its thickness, its superior and inferior arches
were much more developed, and the latter sent down a spine
independently of the interhzemal cartilage, around which a
sheath of bone, which had coalesced above with the posterior
part of the inferior arch, was now visible. The anterior
hypural apophysis had become longer in proportion to its
breadth, and was coated with a thin layer of bone. The pos-
terior hypural apophysis had greatly enlarged both abso-
lutely and in relation to the anterior, and traces of a bony
deposit on its surface were discernible. The number of fin-
rays had increased to fourteen ; of which two, very short, lay
between the end of the interhemal cartilage of the penulti-
mate vertebra and the lower angle of the anterior hypural
apophysis ; six, gradually increasing in length, and becoming
jomted superiorly, embraced the posterior edge of the in-
ferior hypural apophysis; and six, of which the inferior were

HUXLEY, ON THE SKELETON OF FISHES. 41

long and jointed at their ends, while the superior were simple
styles, were connected with the posterior edge of the posterior
or superior hypural apophysis. The terminal osseous ring
(6) had in the meanwhile extended backwards, and now, as a
slender tube, tapering posteriorly and obliquely truncated
behind, embraced more than half the length of the previously
free part of the notochord. As a consequence, the hypothe-
nuse of the still triangular posterior hypural apophysis is
now fixed to bone throughout its whole length, for the end
of the bony sheath in question extends slightly beyond it.
The remainder of the notochord (c) has its wall still mem-
branous and unossified, and ends close to the superior and
posterior angle of the caudal fin as before. There are no fin-
rays above the notochord, nor is any neural arch developed
from the terminal centrum, but the rudimentary interneural
cartilage of the penultimate centrum had greatly elongated,
and had taken the same position relatively to its superior
arch as that occupied by the interhzmal cartilage relatively
to the inferior arch, and had become surrounded by a sheath
of bone. Behind this two other cartilages (m, n) lie parallel
with one another above the ossified sheath of the chorda, but
at present they are connected with no fin-rays. I will term
these the “‘ epiural”’ apophyses.

In a half-grown Stickleback (fig. 3) the anterior end of the
terminal centrum was dilated and cup-lke, just as if it were
the anterior half of one of the ordinary hour-glass-like ver-
tebrze, but instead of dilating again posteriorly, it is continued
into a stout style, more than twice as long as the body of the
penultimate centrum, and curved up so as to make an angle
of 45° with the rest of the vertebral column. ‘This stout style,
with its central cavity, looks not very like the previous deli-
cate sheath of the chorda; but such thickened sheath it really
is, and with care the remainder of the notochord may be traced
beyond it between two of the fin-rays into the tail-fin itself.
The rays between which it lies are the uppermost of the su-
perior set in the last-described embryo, and a new set, six in
number, which have been formed above the notochord. I shall
henceforward term this ossified chordal style the “ urostyle.”

The free part of the notochord no longer reaches, by a long
way, to the posterior superior angle of the caudal fin, for the
fin-rays attached to the hypural apophyses, the uppermost of
which supports the posterior superior angle of the caudal fin,
are now more than twice as long as the free part of the
notochord, and consequently the end of the latter is by its
whole length distant from the present superior and posterior
angle of the fin. The whole length of the free notochord,

VOL, VII. E

42 HUXLEY, ON THE SKELETON OF FISHES.

together with the elongated terminal centrum, is about 1-16th
of aninch. The hypural apophyses are attached along the
under surface of the ossified walls of the notochord. They
are nearly equal in size, and each supports, as before, six rays,
but the number in front of the anterior hypural apophysis
has increased to six or seven.

A short and rudimentary neural arch rises from the anterior
end of the urostyle, and there is an indication of a second
opposite the interval between the anterior and posterior
hypural apophyses, where I have seen traces of what seemed
to be a sutural division of the urostyle into two portions.

The anterior epiural apophysis appears greatly enlarged
and bifurcated at the extremity. Iam inclined to think that
its anterior part represents the neural spine of the anterior
neural arch of the urostyle, but it is separated from it by
a wide interval. The posterior epiural apophysis is also
enlarged and altered in form.

In the adult fish (fig. 4) the urostyle is at once recognisable
as a slender, tapering, bony process, in which an internal
cavity can be observed, and which forms as great an angle
with the axis of the vertebral column as before. The length
of this process, together with that of the terminal centrum, of
which it is a prolongation, is about 1-l4th of an inch, and
no trace of the notochord is visible beyond it, so that I doubt
not it is the result of the complete ossification of the walls
of the chorda. The posterior hypural apophysis is as nearly
as may be of the same size as the anterior, and, like the
latter, carries six large fin-rays. These almost entirely sup-
port the tail, the fin-rays above the notochord not attaining
more than one fourth their length, and constituting only a
very insignificant portion of the root of the tail. The epiural
apophyses are greatly altered, but I need not enter into a
particular description of them.

Thus it appears that Gasterosteus is in reality an excessively
heterocercal fish, the whole of its principal fin-rays being
developed below the vertebral column. It is as heterocercal
as an Accipenser, and far more so than a Scyllium ora
Squatina. Furthermore it appears that the tail of this
Acanthopteran fish has essentially the same structure as that
of the Malacopteran salmon, except that the wall of the
notochord is ossified through its whole extent, whereas in the
salmon it persists in the condition which it has in the young
Gasterosteus. I have not been able as yet to obtain so com-
plete a series of forms of the caudal extremity in the Eel,
but with some extremely interesting minor variations, which
I propose to describe at length on a future occasion, the

HUXLEY, ON THE SKELETON OF FISHES. 43

structure is similar in principle. The tail is truly heterocercal.
What answers to the urostyle is divided into two portions—
the anterior of which supports the anterior hypural apophysis,
the posterior the posterior; and the last is not only superior
to the anterior hypural apophysis, as is the case in the
Gasterosteus, but projects beyond it posteriorly. Seeing the
close resemblance in the structure of the tail which exists
among all Acanthopteri—inasmuch as the hypural apophyses
resemble more or less closely those of the stickleback, and
always bear the principal caudal fin-rays, I make no doubt that
what is true for Gasterosteus is true for all, and by a parity
of reasoning, that what is true for Anguilla and Salmo is good
for all Malacopteri; and I therefore do not hesitate to draw
the conclusion that the Ctenoidet and Cycloidei of M. Agassiz,
so far from being homocercal, are in truth excessively hetero-
cercal; that is to say, more completely heterocercal than the
great majority of Hlasmobranchit.

In the heterocercal tails of the Teleostei there are, how-
ever, at least two well-marked varieties or grades of structure
—the one, which might be called gymnochord tails, having
the end of the notochord unprotected by ossification in its
wall, asin the Steguri of Heckel; the other, which might
be termed steganochord, having the end of the notochord
enveloped in a styliform osseous coat, which there seems
reason to believe represents the centra of two vertebre.
As a common, if not universal, character of the Teleostean
heterocercal tail, by which it is distinguished from that of
Elasmobranchii, we have the peculiar development of the
epiural and hypural apophyses.

But if it be true that all Ctenoids and Cycloids are hetero-
cercal, it is clear that the ground of the argument of MM.
Agassiz and Vogt is completely cut away, so far as mere
heterocercality goes. The ancient and the modern fishes
are precisely on the same footing, and if the palzozoic
Ganoidei and Elasmobranchii really represented embryonic
conditions of existing Teleostei, they ought to be all strictly
homocercal, for it is only m the embryonic state that a
Teleostean is really homocercal.

On the other hand, however, if homocercality and hetero-
cercality are left out of the question, there can be no doubt
that such facts as those brought forward by Heckel respecting
the Pycnodonts show that in certain families of fish, at any
rate, there has been a gradual change from a quasi-embryonic
condition of the vertebral column to one more resembling
that of an adult Teleostean. So perhaps it may be admitted
that the structure of the tail in some modern Ganoids is more

44 HUXLEY, ON THE SKELETON OF FISHES.

like that of the adult Teleostei, while that which obtains m the
ancient members of the same group is more like that of
embryonic T¢Jeostei. But it has never yet been shown, either
that the approximation of a Ganoid to a Teleostean, or the
more complete ossification of the vertebral column in these
or other fishes, is a mark of an advance in general organiza~
tion. I take this occasion of repeating an opinion I have
often expressed, that no known fact justifies us in concluding
that the members of any given order of animals present, at
the present day, an organization im essential respects more
perfect (in whatever sense that word may be used) than that
which they had in the earliest period of which we have any
record of their existence.

It may be asked, in conclusion, whether the peculiar
structure of the tail of the Teleostean tribes is a modification
of the vertebral column altogether peculiar to them, or
whether some trace of it is not to be found in other Verte-
brata. I believe the latter question may be answered affir-
matively, and that just where so many remnants of piscine
characters are found, viz., in the Amphibia, there is a most
interesting representation of this structure. I refer to the
coccygeal style of the Frog and its allies, which, as Dugés origi-
nally indicated (and I have had reason lately to satisfy myself
of the fact), is formed by the coalescence of a styliform ossi-
fication of the end of the sheath of the chorda with two neural
arches. Naturally, as there are no fin-rays, there are no
epiural or hypural apophyses, but otherwise the resemblance
of the two structures is complete.

2. On the development of the palato-pterygoid arc and hyo-
mandibular suspensorium in Fishes.

On examining the region in which the complex mass of
bones comprehended under the above name eventually lies -
in an embryo Gasterosteus, about 4d of an inch long, I
found in their place a delicate imverted cartilaginous arch
attached anteriorly by a very slender pedicle to the angle of
the “facial cartilage” formed by the union of the two
trabeculz cranii, and posteriorly connected by a much thicker
crus with the anterior portion of that part of the cranial
wall which incloses the auditory organ. The crown of this in-
verted arch exhibits an articular condyle for the cartilaginous
rudiment of the mandible. Its posterior crus is not, as it ap-
pears at first sight to be, asingle continuous mass, but is com-
posed of two perfectly distinct pieces of cartilage applied
together by their respective anterior and posterior edges.
The anterior is continuous below with the condyle, but

HUXLEY, ON THE SKELETON OF FISHES. 45

ends above in a free point. The posterior is continuous
with the cranial wall above, but ends below in a free
point immediately behind the condyle. The posterior edge
of this last portion (which I shall term the hyo-mandibular
cartilage, as it is the means of suspension of both hyoid and
mandibular arcs to the skull) has, above, a rounded condyle
for the operculum, while below this, it gives attachment to
that cartilage which eventually becomes the styloid element
of the hyoidean are. That part of the cartilage which lies
above the attachment of this element becomes, by its ossifi-
cation, the “ temporal’? of Cuvier; that which lies below it
gives rise to Cuvier’s “‘ symplectique.”

The anterior division of the posterior crus, the condyle,
and the anterior crus of the inverted arch I have mentioned,
constitute a inverted V-shaped ‘ palato-quadrate” cartilage,
The anterior part of the anterior crus ossifies, and becomes
Cuvier’s “palatine; the posterior part gives rise to his
‘transverse’ and ‘ pterygoid ;” the condyloid portion, when
ossified, becomes his “jugal;” and the extremity of the
ascending process from this or the anterior division of the
posterior crus becomes his “ tympanique.”

The operculum, suboperculum, interoperculum, and pre-
operculum, are developed in the branchiostegal membrane
apart from the other bones.

These embryological facts are of great importance, as they
enable us to understand, on the one hand, the different
modifications of the palato-suspensorial apparatus in fishes,
and on the other hand, the relations of the components of
this apparatus to the corresponding parts in other Vertebrata.

They explain, in the first place, the fact to which Kostlin
first drew attention, that in the Teleostean and Ganoid fishes
there is every gradation, between the most intimate con-
nexion of the “ temporal” and “symplectic” with the other
bones, and their wide separation. They enable us to under-
stand why, in Lepidosteus, for example, the “jugal”’ remains
firmly united with the representatives of the “ pterygoid” and
“tympanic,” while it is connected with the ‘ temporal”? and
“symplectic”? only by the preoperculum; and they prove
that the suspensorial apparatus of the sturgeon answers to
the temporal and symplectic of other fishes, while the carti-
laginous arch to which its mandible is articulated corresponds
with the palato-quadrate arcade of the embryo. Again, to
my mind, they prove that Cuvier was right in denying the
homology of the so-called upper jaw of the Elasmobranchi
with the maxilla and premaxilla of a Teleostean ; for it corre-
sponds precisely with the palato-quadrate arcade of the

46 HUXLEY, ON THE SKELETON OF FISHES.

embryo, giving articulation to the lower jaw, which therefore
is, as in the embryo, only indirectly connected with the so-
called tympanic cartilage, which again is the homologue of
the temporal and symplectic. In this respect, as in so many
others where the skeleton is concerned, the Teleostean em-
bryo is typified by the adult Elasmobranch and by some
Ganoids.

With respect to the homologies of the bones of the fish’s
face in other vertebrata, the evidence of deyelopment appears
to me to be no less decisive. No one who compares the
development of the two will, I think, doubt that in the fish
Cuvier’s palatine is the homologue of the palatine of the abran-
chiate Vertebrata, that his pterygoid is the homologue of their
pterygoid (wholly or in part), and that his jugal is their
quadratum or incus. The comparison with the development
of the frog, furthermore, leayes no doubt on my mind that the
tympanic” of the fish is a dismemberment of the pterygoid,
and has not the remotest relation with the true tympanic,
I can, however, find no homologue of the temporal and
symplectic of the fish in the abranchiate Vertebrata. They
appear to me to he specially piscine elements, which are
only traceable as far as the Amphibia, where they are
represented by that part of the suspensorial cartilage
(quadrate or tympanic cartilage of authors) to which the
hyoid arch is attached, and by the “‘ temporal”? of Cuvier. In
the abranchiate Verterata, if the hyoid 1s connected with the
skull at all, its imsertion is quite distinct from that of the
mandibular arch. I believe, therefore, that the branchiate
Vertebrata, the oviparous abranchiate Vertebrata, and the
Mammalia, present a series of well-marked gradations in the
mode in which the ramus of the mandible is attached to the
skull. In the fish it is separated by the os articulare, the
quadratum, and the temporo symplectic. In the Amphibia the
latter becomes less distinct, In the abranchiate Ovipara it
disappears, but the ramus of the mandible is still separated
from the skull by the articulare and quadratum. In the
Mammata, finally, these are converted into the malleus and
incus respectively, and the ramus comes into direct contact
with the squamosal element of the skull.

47

TRANSLATIONS,

On the DeveLopMENT of Sacirta.
By Dr. C. Grcrnsavr.

(‘ Abhandl. d. Naturf. Gesellsch. in Halle,’ 1857.)

Havine in a former volume of this journal given an ac-
count of what is known respecting the structure and relations
of Sagitta bipunctata, we have thought that an abstract of
Dr. Gegenbaur’s observations on the subject of reproduction
in that genus would not be unacceptable; and the more so,
as this part of the history of Sagitta has hitherto been in-
volved in much obscurity.

In the sea at Messina three distinct species of Sagitta
came under the author’s observation. S. bipunctata, which
he appears not unfrequently to have met with of the large
size of 2” 2’ in length, and two other forms which he was
unable to refer to any known species. One of these, 9!” long,
was of slender shape, attenuated for some distance beyond
the head, and again, beyond the middle of the body, tapering
off suddenly to the caudal extremity, had two pairs of lateral
and one caudal fin; the former rounded and projecting but
little, whilst the caudal fin was very broad. The surface of
the body, moreover, was studded with warty tubercles, occa-
sionally disposed with perfect symmetry and supporting
bundles of fine sete. The head triangular, somewhat
acuminate in front. The other species was less common,
the largest individuals not more than 6’ in length, the body
almost cylindrical, very slightly constricted behind the rather
broad head, and truncated at the caudal extremity; the
whole surface of the body was covered with very numerous
bundles of set (0:08 in length), which gave it an almost
villous aspect. The anterior lateral fins, very long and nar-
row, commenced at the end of the first quarter of the length,
terminating in a projecting point about the middle of the
body. The posterior pair, wider in proportion, had a strongly
curved border. The caudal fin was abruptly rounded oft.
Both species were transparent, and had, like all their con-
geners, two brown pigment-spots behind the opening of the
vasa deferentia. No important distinction could be drawn

48 GEGENBAUR, ON SAGITTA.

from the oral hooklets. From two of these three distinct
species Gegenbaur obtaied mature ova, derived from preg-
nant individuals kept for the purpose in glass vessels,

The spawn was deposited in good-sized masses of a sub-
stance not unlike swollen sago-grains. The period at which
they were most abundantly met with extended from the end
of January to the beginning of March.

The deposited spawn always lay unattached on the bottom
of the glass vessel, and consequently when in the sea is pro-
bably pelagic, that is to say, the sport of the waves. In
confirmation of which similar masses of ova were occasionally
taken with a fine towing-net. They bere no resemblance to
the ova described by Darwin as belonging to Sagitta.

The ova were enveloped in a gelatinous substance, which,
however, did not appear to surround each ovum separately,
but to appertain to the whole mass of eggs in common. In
this respect some resemblance may be observed with the
condition presented in Terebella, Protula, and <Arenicola,
as well also as in the Hirudinee and those Lumbricina in
which several ova are associated in one capsule (e. g.,
Senuris).

The spawn of Sagitta, therefore, is closely allied to that of
Annelids, and differs essentially from that of the Mollusca,
and especially of the Gasteropoda, whose ova, besides the
general gelatinous envelope, present also an albuminous
covering surrounding each separate vitellus or several toge-
ther, when the outer layer is hardened into a membranous
case.

The size of the ova varies according to the species. Those
of the small species measure /,", and of the larger 1”. In
other respects they are alike, perfectly spherical, and almost
perfectly pellucid, with a shghtly yellowish tinge, and fur-
nished with an extremely delicate vitellme membrane.

In the centre of the yelk lies the resistant, yellowish ger-
minal vesicle (nucleus), having a diameter about th of that
of the vitellus. No germinal spots (nucleoli) were noticed.
Before segmentation has taken place, the vitellus appears to
be composed of a perfectly homogeneous substance contain-
ing minute molecules, which are more closely crowded
towards the centre than in the peripheral portion. The
segmentation of the yelk, as well as the entire process of
development, is quickly ended, occupying the space of seven
to nine days. ‘The process of development was the same in
the ova of both the species observed.

Segmentation commences with the appearance of a groove
following the equatorial line of thevitellus, but beneath the vitel-

GEGENBAUR, ON SAGITTA. 49

line membrane, which divides the yelk into two equal hemi-
spheres. This groove or depression, over which the vitelline
membrane is stretched like a bridge, penetrates more and more
deeply into the vitelline substance, until a complete separation
is effected, between the two portions which simply remain in
contact. The next division separates each hemisphere into
two segments, the yelk now appearing to be composed of
four segments of a sphere.

Where the four segments meet in the centre of the vitel-
lus, a minute hollow space may be observed, formed by the
rounding off of the contiguous angles of the four segments,
This central space is of no small importance in the further
stages of the process.

Whilst these changes are going on, the molecules above
described as surrounding the germinal vesicle, and which
are subsequently ageregated around the nucleus of each
segment derived from the division of the original vesicle,
assume a peculiar disposition. They become more densely
packed around the nucleus, from which they extend in ra-
diating lines towards the periphery.

Each of the four vitelline segments is now again sub-
divided into two equal portions in a direction perpendicular
to the middle of its longitudinal axis, so that the whole yelk
is constituted of eight equal segments. By a continuance of
a similar divisional process the number of pyramidal segments
goes on increasing, each pyramid having the apex directed to-
wards the centre of the vitellus. An arrangement owing to
which the segmentation of the ovum of Sagitta appears under
a very remarkable type. Even in these latter periods of the
process of segmentation, the segments never assume a sphe-
rical form as in the Mollusca and Annelids, as well as in
the Vertebrata, nor constitute the aggregate masses so well
known in their mulberry-like form. On the contrary, in the
present case, owing to the circumstance that certain condi-
tions, in other instances occurring only in the earliest stages
of segmentation appear to remain persistent, it happens that
a single segmentation-cell extends from the centre of the
vitellus to the surface, and at the same time, whilst multi-
plying, the contiguous segments are closely in contact by
their corresponding surfaces, in consequence of which they
become mutually flattened. Pyramidal segments of this
kind do not, so far as Gegenbaur is aware, occur in any
other case. The summit of each of these four- five- or six-
sided pyramids is truncated, and contributes to the forma-
tion of the boundaries of the vacant central space in the
vitellus above described. The basis of the pyramid does not

50 GEGENBAUR, ON SAGITTA.

correspond in its curvature with a superficial area of the same
size on the surface of the yelk, but forms the segment of a
far smaller sphere, so that on a superficial view of the ovum,
the mulberry-like stage of segmentation appears to be simu-
lated.

On the second day the whole vitellus is subdivided into
numerous pyramids which are in close contact, and form the
boundary of a central cavity which has now attained a con-
siderable size.

Before describing the subsequent formation of the embryo,
Gegenbaur refers to some particulars, only briefly noticed
before, respecting the formation of the products of the seg-
mentation and their true nature, as well as to the relations
of the primordial germinal vesicle to the nuclei of the latter,

The fact of the segmentation taking place beneath the vitel-
line membrane, which does not become involved in the process
of development, may at first sight, he says, perhaps, excite
astonishment—a proceeding of this kind appearing to be
opposed to our theory of the process of segmentation as well
as to our notions respecting the multiplication of eels in ge-
neral. It might therefore be supposed that I have regarded
some accessory structure as the vitellme membrane, whilst
the true vitelline membrane either participates im the seg-
mentary process, or, as many observers have stated, disap-
pears at the commencement of the process. In the present
case, however, Gegenbaur says, it is self-evident that he does
not, under the term vitelline membrane, intend any egg-case
(Fihiille), but only that membrane which is formed origi-
nally with the yelk, and surrounds it while still in the ovary ;
and which, in that situation, already exists at a time when
the interspace between it and the germinal vesicle scarcely
exceeds the diameter of the latter. This condition of the
vitelline membrane recalls the observations of De Quatre-
fages in Hermella, and of O. Schmidt in Amphicora, in which
cases segmentation also takes place beneath the yitelline
membrane.

The question whether the products of segmentation in the
ovum of Sagitta, after the primitive vitelline membrane has
become detached from them, be still provided with a mem-
brane, and consequently represent true cells or not, cannot
be answered until what is a ‘“cell-membrane” has been
defined ; and, in Gegenbaur’s opinion, this can be comprehen-
sively done by our regarding as a membrane the outermost
thickened layer of a cell, whatever thickness it may possess,
or in whatever physico-chemical relation it may stand
towards the cell-contents.

GEGENBAUR, ON SAGITTA, 51

Regarded in this ight a membrane may be found to exist
around the products of segmentation in the oyum of Sagitta,
which membrane in the earliest stages of the development,
it must be confessed, differs but little from the interior vitel-
hne substance, and which (physically, at any rate) bears the
same relation to the vitelline membrane that the primordial
utricle in a plant-cell does to the cellulose membrane,

Each segmentation-cell presents an oval nucleus, which at
first is situated in the thicker or outer portion of the cell,
and consequently near the surface of the ovum. What
becomes of it in the process of division has, in the most
important particular, escaped Gegenbaur’s notice; though
it is to be remarked that a stage was often noticed at
which many of the nuclei, much elongated, exhibited con-
strictions ; so that, although a division of the nucleus was not
seen, still such a division might be concluded to take place ; to
which may be added the circumstance that in no case is the
cell without a nucleus. Consequently there is nothing to
support the notion of a disappearance of the nucleus before
segmentation, and a new formation of nuclei after that pro-
cess has been gone through. That this stage of nuclear
division has escaped observation, may perhaps be explained
by the rapidity with which it takes place. The same obser-
vation holds good of the germinal vesicle, the nucleus of the
ovum, regarded as a cell from which all the nuclei of all the
tubsequent cells arise in the same way that the latter have
shemselves arisen from the ovum-cell. In the earhest stages
of segmentation the nature of the nucleus was shown In a
more precise manner, inasmuch as at that time, and before
complete diyision of the yelk, two nuclei were seen to exist.

A peculiarity of the vitellus in the ovum of Sagitta was
noticed at a later stage of segmentation. When more highly
magnified, the contents of each cell were seen to be com-
posed of spherical bodies somewhat flattened by mutual
pressure, and which, at the situation of the nucleus retreating
from it, left a cavity. From the nuclear cavity thus formed,
radiating prolongations stretched out among the neighbour-
ing vitelline granules.

The first indication of the development of the embryo is
shown in a division of the pyramidal vitelline cells, each of
which is subdiyided im the middle of its longitudinal diame-
ter, so that the central cavity of the vitellus becomes
enclosed by an internal layer composed of smaller cells,
which again is surrounded by a layer of larger cells, of
which the surface of the vitellus is also constituted. The
longitudinal axis of each of the outer cells coincides with

52 GEGENBAUR, ON SAGITTA.

that of a cell of the mner layers, and those cells whose axes
thus coincide, had constituted, in the immediately precedent
stage, a single cell. The two layers are of pretty nearly the
same thickness, and m each may be seen a long, oval, central
nucleus.

But whilst this division is goimg on, the central cavity
of the vitellus enlarges, the cells by which it is bounded
gradually becoming more and more remote from the central
point ; but at the same time its figure is so irregular, that 1%
would hardly be supposed that it could be the rudiments of
an important part. But its true nature is soon made mani-
fest from an opening which, gradually becoming more and
more evident, places the hitherto closed cavity in communi-
cation with the exterior. In this way arises a short canal
perforating the two layers of cells, so that the original cen-
tral cavity might now be regarded as the cecal termination
of an invagination or depression commencing from the
exterior, unless one had not been satisfied, from previous
observation, that its existence dated from a far earlier period,
as early even as the first stage of segmentation.

The essential nature of the process by which the canal is
formed is, for the most part, unknown; it is an act closely
connected with the innermost vital phenomena, not only of
the cells in the immediate region concerned, but which must
also result from certain changes equally affecting a// the cells
of which the embryo is composed.

Observation has shown Gegenbaur that no mere absorption
of the cells, or, at any rate, that no complete disappearance
of existing morphological elements takes place, but that the
opening of the central cavity is the immediate result of a
separation from one another of certain parts of cells (Zell-
parthien).

Were it true that a solution of the cells took place, the
products of such a process would be visible, and were the
proceeding one of simple absorption, in some way set up by
the contiguous cells, the boundary or outline of the canal
thus produced would have an appearrnce different from that
‘which it actually presents. The cells forming the boundary
of the canal are disposed somewhat differently to the rest ;
simultaneously with the formation of the canal, they have
the direction of their longitudinal axis changed in such a
way that this axis in the centre of the embryo no longer
coincides with that of the other cells which remain un- °
changed, but appears rather to be directed towards the canal
itself. At the same time these cells, both of the internal
and of the external layer, have hecome somewhat shortened.

GEGENBAUR, ON SAGITTA. 53

Viewed from the surface, the external opening of the canal
—the future mouth, since the whole cavity becomes the
intestinal canal—appears in the ova of Sagitta bipunctata,
as a round, funnel-shaped depression, whilst in the ova of
the smaller species it appears to be more elongated trans-
versely.

The whole history of comparative deveiopment offers
nothing analogous to this surprising mode of formation of
the rudimentary intestine out of a central cavity which
makes its appearance in the earliest stages of segmentation
of the vitellus ; and in this respect, again, Sagztta appears to
constitute a paradoxical form.

When this canal and the central cavity into which it leads,
and which increases in size and becomes irregular in form,
have been fully developed, the embryo still completely fills
the vitelline membrane, by which it is closely invested on
all sides, excepting at the spot where the mouth is situated,
and where the surface of the body presents a shallow de-
pression.

The two layers of cells, of which alone the body of the
embryo is, up to this time, constituted, are now broken up by
a further transverse division of the individual cells, so that
more rounded embryo cells soon become visible. —

In consequence of an increase in the length of the hitherto
spherical embryo, the body now necessarily becomes curved ;
a change which indicates a new and not less characteristic
stage. There now takes place a farther differentiation of the
layers of cells which were apparent at a former period. Of
the cells produced from the single internal layer a stratum is
formed whose clear and minute elements immediately sur-
round the intestinal canal, and are clearly distinguishable on
the outer aspect from the peripheral layer of cells formed from
the simple outer layer. These layers, therefore, composed of
numerous superimposed cells, correspond each with one of
the primitive strata, which, we have seen, were derived from
a transverse division of the simple pyramidal cells.

The central stratum Gegenbaur regards as the rudiment
of the intestinal wall, and in the peripheral he recognises the
integument of the body.

The anterior and posterior ends of the body approach each
other, so that the mouth comes to lie within the point of
incurvation. The convex surface of the embryo, therefore,
corresponds to the dorsal aspect. Of the further changes
in the embryo, nothing precise seems to have been observed.
On the ninth or tenth day the animal is completely formed,
and begins to manifest its maturity by struggling move-

54 KOLLIKER, ON MUSCULAR FIBRE.

ments, in consequence of which the enveloping membrane
is ruptured. .

The development of the greater part of the iiternal organs,
except the intestine, appears to take place after the escape of
the embryo from the egg. No trace of the nervous system
is at that time apparent, and but one pair of lateral fins
exists.

The following summary contains the main points of Gegen:.
baur’s observations. .

1. The products of segmentation of the vitellus are
elongated pyramidal cell-forms, which retain this character
even after the appearance of the rudiment of the embryo. _

2. The formation of the rudiment of the intestinal canal
accompanies the segmentation of the vitellus.

5. The intestinal canal appears at first as a central vitel-
line cavity, its opening externally being a secondary process.

4. The development takes place without any metamorphosis,
and even without the appearance of cilia on the surface of
the embryo.

After a short discussion of the views of various authors
respecting the systematic position of Sagitta, and a review
of the principal points, chiefly embryological, connected with
this still doubtful question, Gegenbaur concludes with ob-
serving that the “genus Sagitia must be regarded as the
representative of a special subdivision between the Nematoda
and Annelida, and which might be designated the “ Pfeil-
wurmer ” or “ Arrow-worms.”

The paper is accompanied with figures illustrating the
process of development.

On the DrvetopMent of the TransvERSELY STRIATED
Muscurar Fisre, in Man, from Simpte Criis. By
Professor A. KOLLIKER.

(Siebold and Kolliker’s ‘ Zeitsch. f. w. Zool.,’ vol. ix, p. 129.)

Te extensive prevalence of unicellular muscular fibres or
of contractile fibre cells in the Invertebrata having been de-
monstratively shown, I was induced to inquire whether the
mode of formation first noticed by Lebert, and afterwards
by Remak, in the transversely striated muscular fibre of the

KOLLIKER, ON MUSCULAR FIBRE. 5p

frog, that, viz., acccording to which each muscular fibre is pro-
duced from a single cell, which becomes exceedingly elon-
gated, did not apply to the case of ail transversely striated
fibres (‘ Wiirz. Verh.’ viii. p. 113). Iam now, in fact, enabled
to show that the same mode of formation also obtains in the
human subject. In a two-months embryo I found the
muscles of the rudimentary foot in so undeveloped a condi-
tion, that it was by no means difficult to exhibit their very
early conditions. The earliest forms seen by me were simple
fusiform cells, 0‘06—0°08” long containing in the middle por-
tion, which was 0:001—0'015” in breadth, one or two elongated
nuclei, and produced at either extremity into an extremely
delicate filament at most 0:0004” im diameter, presenting at
the same time no trace of transverse striation. Now from
the muscular substance of the thigh and leg a complete
series of forms, from these simple fibre-cells, which could be
nothing else than elongated primordial embryo-cells, could be
traced up to fibres 0°2—0°3” long and 0:002” wide, which were
also attenuated at each end, and containing 4—9 elongated
nuclei placed at considerable distances apart, and also pre-
senting the first faint indications of a transverse striation, so
that it could not be doubted that the future muscular fibres
are derived simply from a growth in length and breadth of
the original uninucleated fibre-cells, accompanied with an
energetic multiplication of the nuclei; to which growth is
subsequently superadded a peculiar transformation of the cell-
contents. And this conclusion was the more readily arrived
at from the circumstance that the nuclei of these elements
presented almost all the indications of an active multiplica-
tion, which I have already described.

I am convinced that in more advanced embryos the
pointed extremities of the muscular fibres will also be found ;
and it would also, as it seems to me, appear that these ob-
servations explain the recent discovery by A. Rollett of the
occurrence of numerous free, pointed extremities of the mus-
cular fibres in the adult.

If in the frog and in man the muscular fibres represent
simple vastly enlarged cells—which, it may be remarked, is a
strong proof of the active formative capacity of the animal
cells—it can no longer be doubted that the same holds good
of all transversely striated muscular fibres, nor in future can
any distinction be drawn between contractile fibre-cells and
muscular fibres as representing numerous cells. Certain
distinctions will in all cases remain, with respect to which I
would at present remark that the circumstance whether the

56 KOLLIKER, ON MUSCULAR FIBRE.

elongated muscle-cell contains only one or several nuclei,
affords a useful basis of arrangement. The degree of differ-
entiation also, as heretofore, may also be regarded, though
this is a point, which, as I have shown on a previous occa-
sion, is of less weight.

~

or

REVIEWS.

Humble Creatures.—The Earthworm and the Common House
Fly. By James SaMvuE.son, assisted by J. B. Hrexs,
M.D., F.L.S. London: Van Voorst. 1858.

THE appearance of works lke this little book affords
strong evidence of the fact that the study of natural science
is gradually becoming a general object of pursuit. The
popular mind is obviously begmning properly to appreciate
the interest and value attached to the observation and
investigation of natural phenomena, and even to perceive
that the modes of thought and methods of inquiry demanded
and promoted by such studies, constitute their real value,
urespective in great measure of the special subject of the
inquiry.

When we find that men like the authors of this book,
engaged in the active pursuit of a mercantile or of a pro-
fessional life, yet find time and inclination to employ their
rare leisure in the observation of the common objects around
them, it cannot be denied that the minds of practical men,
as they are termed, are, at any rate, alive to the advantages
and delights of scientific pursuits.

The object of studies like those undertaken by Mr.
Samuelson may be regarded as twofold. In the first place,
as conducive to the formation of habits of close observation
and comparison, they must ever be regarded as an important
element in the education of the judgment and of the mental
powers in general; whilst, as he observes, “ the pleasurable
sensations arising from the investigation of those objects, of
which the book treats, render those studies a delightful
recreation, and the most effective mode of relaxation for
those whose days are passed, and whose minds are occupied,
in the oppressive cares of business.”

To one who rightly feels the true import of such studies,
and is capable of properly appreciating the enjoyment to be
derived from them, the particular subject of investigation
will be a matter of less importance than the spirit and mode
in which the inquiry is approached and carried on.

This appears to have been the author’s idea when he

VOL. VII. F

58 SAMUELSON, ON HUMBLE CREATURES.

selected as the subject of his labours such common objects as
the earthworm and the house-fly, whose extreme vulgarity
would lead many to deem that they were beneath the notice
of the scientific student. It is, however, a very important
principle to bear in mind, that in most cases the rarity of
any object, or the difficulty of obtaining it, in no way adds
to its value as a subject for the exercise of observation and
research. In a scientific point of view, it is quite true that
the commonest objects are, in most respects, as interesting
as the rarest. The laws of biology, or the physiological and
structural relations of living beings, may be as well studied
and as profitably investigated in the commonest as in the
rarest creatures. As Mr. Samuelson’s book will serve to
show, no one need go far from his threshold, nor spend
much time and money in the search after objects upon which
to spend his leisure hours of observation. It may be
remarked also, as in the case more particularly of the earth-
worm, that it not unfrequently happens that the commonest
and apparently meanest objects are those about which least
is really known. ‘The structure of the common worm, it is
needless to say, is as perfect and beautiful as that of the
highest animal; but common as it is, and numerous as have
been the observations made with respect to it, many points
in its structure, physiology, and habits, of the utmost
importance, yet remain to be made out, a knowledge of
which would nevertheless tend to throw very considerable
light upon similar points in a great number of the annulose
class, which are far less easily procured. Nothing, for
instance, is yet really known with respect to the mode or the
situation in which, or the period when, the ova of the earth-
worm are impregnated; nor, which is perhaps still more
strange, do we know with certainty how the ova are expelled
from the parent. The most recent researches on these
points by D‘Udekem and Hering have, it is true, indicated
the true situation and some of the relations of the ovaries,
and the complicated structure of the male reproductive
organs; but further than this inquiry has not yet gone.
We cite this particular instance merely to confirm the pro-
position that, even in the commonest objects, much may yet
be left for even the best informed inquirer to complete, and
that they will at any rate always afford to the beginner
abundant materials for his research.

With respect to the mode in which Mr. Samuelson has
executed his task, we need only remark that, although he
has very properly expressed himself in an easy and popular
manner, his treatment of the subject is by no means super-

SAMUELSON, ON HUMBLE CREATURES. 59

ficial or inexact. He has obviously and successfully endea-
voured to make himself acquainted, both by direct observation
and by reference to the best and most recent authorities, with
the subjects upon which he treats. As might be expected,
the account of the fly, which occupies about two thirds of the
volume, is more lively and interesting to the general reader
than that of the worm, and in this part of his work he has
received considerable assistance from the pen and pencil of
Dr. Hicks, whose name is well known as a most careful and
skilful microscopic observer of many points in the structure
of some parts in various insects, by papers published in the
‘Proceedings and Transactions of the Linnean Society.’

We can strongly recommend Mr. Samuelson’s work to all
young naturalists, and more especially will those who employ
the microscope in the investigation of the structure of insects,
find in it many novel and interesting observations.

60

NOTES AND CORRESPONDENCE.

New Forms of Diatomacee——The following remarks are
from a paper published by Professor Gregory in the ‘ Trans-
actions of the Royal Society of Edinburgh,’ on “ New Forms
of Diatomacez found in the Firth of Clyde and in Loch
Fine.” For a description of the new species we must refer to
the paper.

““TIn two papers read before this Society, I have very fully
described the Diatomacez of the Glenshira Sand, which is
very remarkable both for the large number of species found
in it, which is certainly more than 320, and for the circum-
stances in which it must have been deposited. There can be
no doubt, from the nature of the locality, which I have
lately visited, that this bed was formed in the bottom of the
Dhu Loch, a shallow fresh-water lake, at that time extending
about two miles farther up the valley than it now does, and
being at a higher level. In consequence of a rise in the
level of the land, or a fall in that of the sea (from which—
that is, from Loch Fine—the lower end of the lake is sepa-
rated by a narrow and low barrier, through which the
waters of the lake pass to Loch Fine), the lake has long ago
been drained, till its upper end is nearly two miles from the
point it must have reached when the bed of sand was
formed. The present level of the lake is considerably lower
than it was then; the precise difference I had no means of
ascertaining, but I believe it is about 30 feet. Now, the
most interesting fact about this lake is, that its actual level
is that of half-tide, so that at low water the lake is discharged
into the sea, while at high water the tide flows upward into
the lake. Hence marine plants and animals are found in
the Dhu Loch; herring, for example, are often caught in it,
and were taken while I was in the neighbourhood. Hence
also the present deposit in the lake exhibits a mixture of
fresh-water and marine Diatomaceous forms. Now, the
older sand, the subject of my paper, deposited at a conside-
rably higher level, also contains both marine and fresh-water
Diatoms ; and while the individuals of the two classes are
both abundant, the marine species are at least twice, perhaps
thrice, as numerous as those of fresh water.

“The natural, and, I have no doubt, the true explanation

MEMORANDA. 61

of the occurrence of so many marie forms in an inland
deposit, formed in a fresh-water lake, is this: that at the
period when the sand was formed the relative levels of the
Dhu Loch and of Loch Fine were the same as now, when
similar results ensue.

“ But as the lake was then at a higher level than now, so
also must the sea have been at a level as much above its
present one. This conclusion is in accordance with those
derived from the observations made on raised beaches on the
banks of the Firth of Clyde, the level of which must always
have regulated that of Loch Fine since the present form of
the coast has existed.

«There was, however, a circumstance which at first tended
to throw some doubt on this conclusion, according to which
the marine forms of the Glenshira sand must have come
from Loch Fine. For although the known and described
marine Diatoms found in the sand occur on our coasts, yet I
was struck with the fact that out of upwards of fifty new or
undescribed forms, there seemed to be no trace in deposits
from the Firth of Clyde, examined by more than one natu-
ralist during the progress of my investigation. The fact of
these forms being undescribed was prima facie evidence that
they had not occurred on the British coasts.

“Yet it was evident that the formation of the Glenshira
sand, was, geologically speaking, very recent; so recent,
indeed, that we could not suppose.any number of species
to have since become extinct. I came, accordingly, to the
conclusion, that these undescribed forms must still exist in
the waters of Loch Fine, or, what is the same thing, of the
Firth of Clyde. I was therefore desirous to examine with
care deposits from these waters, and this, during the past six
months, I have been enabled fully to do.

“The materials which I have examined are the follow-
ing :

“1. A small quantity of dirt or sand washed from some
nests of Lima hians, dredged in Lamlash Bay on the 19th
of July last, in four fathoms, by Professor Allman. This
material, though, when cleaned, very scanty, proved the
richest of all.

2. Four dredgings, made by myself, with the kind assist-
ance of the Duke of Argyll, in Loch Fine, at different
points within two or three miles of Inverary. These were
all different, and three of them were interesting. They were
taken at dephts of from fourteen to eighteen fathoms, early
in October.

62 MEMORANDA.

“3. Three dredgings made at the same time by the Rev.
Dr. Barclay, in Loch Fine, off Strachur, at depths of fifteen,
twenty, and sixty fathoms, also in October last.

“4. Three materials: forwarded to me in October by the
Rey. Mr. Miles, of Glasgow, who was for some time on the
Holy Island, in Lamlash Bay.

“One of these was washed from the nests of the Lima
hians, as I had reported the richness of the former. These
last were from seven fathoms in Lamlash Bay. This mate-
rial, dredged, I think, in June, was not so rich in Diatoms
as Professor Allman’s, but yet contained many interesting
forms.

“The second was a coarse red sand, dredged off Invercloy,
Arran, which was rather poor.

“The third was a mass of Corallina officinalis, taken with
the hand, in rocky pools, at Corregills, Arran, when the tide
was low. ‘The Corallina, proved to have been a good
Diatom trap, and yielded a material, not remarkable for the
number of species, but rich in individuals, and these nearly
all of interesting, rare, or new species.

“| had thus eleven different materials, no two of which
were exactly alike, although im all certain prevalent forms
occurred. In each, on the other hand, some forms, few or
many were peculiar, and their presence gave a distinct cha-
racter. A careful study of the whole has yielded interesting
results; and these it is the object of the present paper to
state as briefly as may be consistent with accuracy.

“The first observation is, that these waters contain a very
large proportion of all the known and described marine
forms belonging to Britain, including a good many which
have hitherto been very rare; so scarce, indeed, in some
instances, that few observers have seen them. I may specify
the following as being by no means rare, several, indeed,
being abundant in these materials:

Coscinodiscus concinuus. Pleurosigma delicatulum.
Eupodiseus crassus. Ks transversale.
is Ralfsii. Surirella lata.
‘s sculptus. Himantidium (?) Williamsoni.
Campylodiseus Ralfsit. Amphiprora elegans.
Horologium. Podosira Montagnei.
Navicula Hennedyi. Orthosira marina.
a Granulata, Bréb. Grammatophora macilenta.
» _ Lyra, Ehr. Biddulphia Baileyi.
Pleurosigma rigidum. a turgida.
" obscurum.

“The second observation which I made was, that, as I had

MEMORANDA. ; 63

anticipated, nearly the whole of the new forms figured by
me from the Glenshira sand are found living, and generally
abundant, in these waters. The following list contains the
names of such of the marie species, figured in my former
papers, as I have found in the new materials :

“ Cocconeis distans, Navicula diuyma 6.

7 costata. 23 crassa.
RKupodiseus Ralfsii; also var. 6, sparsus. Pinnularia Pandura.
Campylodiscus simulans. 5 longa.
Surirella fastuosa, very large. 3 inflexa.
Amphiprora recta. Amphora Arcus.

~ lepidoptera. 3 crassa.

Navicula rhombica. ne elegans.

be maxima. be plicata.

i, angulosa, and var. £. f. obtusa.

x humerosa. * Grevilliana.

_ latissima. a rectangularis.

3 clavata. % lineata.

an splendida. Synedra undulata.

% incurvata. Tryblionella constricta.

e didyma, var. y, costate. # apiculata.

“TY think we can hardly doubt that all the new Glenshira
marine forms will ultimately be found in the neighbouring
waters.

*‘ Before going farther, I have to remark, that two of the
forms in the first list above given, namely, Campylodiscus
Horologium and Himantidium Williamsoni, which had only
been found by Professor Williamson, who detected them
both in a dredging made by Mr. Barlee on the coast of
Skye, im which they were very scarce indeed, have occurred
abundantly, the former in one of the Loch Fine dredgings,
and sparingly in some of the others, the latter m another of
them, and, though less abundantly, yet frequent in nearly
all the Clyde materials. We shall see Himantidium Wil-
liamsoni, which Professor Smith had referred doubtfully to
that genus, not having been able to see more than the front
view of it, is really no Himantidium ; the side view, which is
very abundant in one of my dredgings, having characters
quite incompatible with the genus Himantidium. On this
account, I shall refer to it among the new forms which I
have to mention. I have found it a matter of very great
difficulty, if not impossible, to refer it to any of the genera in
Smith’s ‘Synopsis.’ I may here add, that Synedra undulata,
which I had recognised in the Glenshira sand, but which
had never occurred entire in that deposit, is frequent in the
first material from Lamlash Bay (Professor Allman’s), where
it occurs quite entire in more than half of those I have seen,

64, MEMORANDA.

and, as I had concluded, from the imperfect specimens I had
seen, attains a length of from 0:015 to about 0°02, which,
for a Diatom, is gigantic. I had previously noticed a frag-
ment of it in arecent gathermg made by Professor Smith, and
he had himself subsequently found it frequent in Cork harbour.
The first observer, however, was Professor Bailey, of West
Pomt, New York, who had found it still larger on the
American coast, which I was not aware of till long after my
observations on the Glenshira sand were made.

*‘The third observation I shall here record is, that in these
dredgings I found, in sufficient abundance, several very
curious forms which had occurred in the Glenshira sand ;
but the description and figuring of which I had postponed,
because either they were so scarce that I could not obtain
good specimens, or, being only found in a fragmentary, de-
tached, or imperfect state, I was quite at a loss to determine
their true nature and position. I think I may say that in
every such case I have been enabled, by the study of the
new materials, to understand the nature and structure of
these obscure or doubtful forms, and to establish them as
new and distinct species. I have also been enabled to under-
stand better several of the forms which were figured in my
former papers, and to correct some errors which had crept
into these.

“J need not here give a list of the forms just alluded to,
as the will be included in that of the new forms to be de-
scribed. In that list I shall mark them with a G, to indi-
cate that they were first noticed in the Glenshira sand.

“Lastly, i the new materials I have found a large
number of entirely new and undescribed species. I may
here mention, that although a good many fresh-water
forms do occur in these dredgings, as must, indeed, be |
the case, since the Clyde and all its tributaries bring
down such forms, yet the new forms in question appear
to be all of marine origin. They are, in general, much
too abundant to have been derived from any other
quarter, whereas the fresh-water forms among them are
much scattered. It is proper also to state, that although
all these forms are, to the best of my belief, new to Britain,
yet a few of them have been described by Ehrenberg in some
of his numerous works, and also by De Brébisson. The
great majority, however, have not anywhere been figured ;
not, at least, in any works accessible to me.”

65

ZOOPHYTOLOGY.

On some MApDEIRAN Potyzoa.
Collected by J. Yatzs Jounson, Esq.

(Continued from No. XXIV, p. 263.)

We continue the account of zoophytes, brought by Mr.
J. Y. Johnson from Madeira, and to which he has made some
interesting additions in the present year, and kindly placed
at our disposal for description. In the next number of the
Journal we hope to be able to include figures of all the
remaining new or imperfectly described forms brought by
Mr. Johnson, and shall then give a general list of the known
species derived from that most interesting locality.

1. PoLtyzoa CHEILOSTOMATA.
1. Gen. Cellaria, Lamx.
1. Cellaria Johnsoni, B. Pl. XXII, figs. 4, 5.

Front cell elliptical, surface and ridges smooth ; a ridge passing from each
side of the front of the cell.

Hab. Madeira, Johnson.

Nellia Johnsont, A agg: Journ.,’ No. xxii, p. 125, Pl. XIX,
g. 2.

A figure taken from an imperfect and worn fragment was
given in the last part of the Zoophytology, and the species is
there referred to the genus Nellia. ‘The examination, how-
ever, of the beautiful and perfect specimens collected in the
present year by Mr. Johnson, necessitates its removal from
that genus, and its reference to Cellaria, Lam., used as
synonymous with Salicornaria, Cuvier and ‘B. M. Cat.’ Our
reasons for preferring the term Cellaria to Salicornaria will be
given at another opportunity. The present is an elegant and
very distinct form.

2. Gen. Serupocellaria, V. Bened.
1. Scrupocellaria Delilit, Aud. (sp.) Pl. XXII, figs. 1, 2.
Operculum entire, suboval; a marginal spine on either side above. A
small sessile avicularium on the front of each cell immediately below the
aperture. Peristome smooth.
Hab. Madeira, Johnson; Mediterranean (?), Savigny.
Crisia Delilii, Savigny, ‘ Egypt,’ pl. xii, fig. 3 ; Audouin, ‘ Expl.,’ I,
p. 242.

66 ZOOPHYTOLOGY.

A very distinct species, characterised at once by the minute
sessile avicularium, with an acute triangular avicularium
immediately below the aperture. The presence of this organ
and the smooth peristome distinguish it sufficiently from
S. Macandrei, B., the only other species with which it could
possibly be confounded. Savigny’s figure is very correct to
nature, so that no doubt whatever can be entertained of the
identity between the Madeiran and Levantine (?) forms.

3. Gen. Lepralia, Johust.
1. L. Pouilletii, Aud. Pl. XXTI, fig. 6.

Cells oval, front marked with radiating lines of minute puncta. Mouth
raised, and advanced in front, with five or six marginal spines above.

Hab. Madeira, Johnson; Mediterranean (?), Savigny.

Esch. Pouilletti, Savigny, ‘ Egypt,’ pl. xii, figs. 1—5; Audouin,
* Expl.’ p. 240.

This is another of Savigny’s species, with respect to whose
identification little or no doubt can be entertained. It is
readily distinguished from L. radiata, Moll., by the absence of
the large avicularia and the uniformity of the front of the
cell.

2. L. discoidea, nu. sp. Pl. XXII, figs. 7, 8.

Cells disposed in regular lines radiating from a centre, closely aduate,
immersed. Mouth with a raised margin, keyhole shaped. Surface pitted.

Hab. Madeira, Johnson.

4. Gen. Eschara, Linn.
l. #. distoma. Pl. XXII, figs. 10—12.

Polyzoary ligulate, subterete, branches narrow. Upper part of cell much
advanced; mouth arcuate, expanded below. Beneath the mouth, in the
centre, an acute elongated avicularium, and below that, in the front of the
cell, a depressed space, perforated at the bottom with two rows of minute
pores. Surface minutely granular or wavy.

Hab. Madeira, Johnson.

This is the species described in last part of Zoophytology,
from an imperfect fragment, as L. distoma, B. It is, however,
as there suggested, clearly an Eschara.

5. Gen. Cupularia, Lamx.

l. €. Lowei, Gray (sp.)
2. C. Canariensis, n. sp. Pl. XXIII, figs. 6—9.

Polyzoary depressed, circular, about 0:5” in diameter. Front of cell sub-
rhomboidal, expanded below the middle, aperture oval. Lamina granular,
with an entire margin. Back divided into quadrangular portions, in each of
which are from two to four perforations.

Hab. Madeira, Johnson; Canaries, McAndrew.

A distinct and well-marked form. Numerous specimens

ZOOPHYTOLOGY. 67

were bought from the Canaries by Mr. M‘Andrew two or
three years ago.

3. C. Johnsoni, n. sp.? Pl. XXIII, figs. 1—5.

Polyzoary conical, about 0°25” in diameter. Area of cell subelliptical,
widest about the middle. Raised margin surrounding the upper part or
oval portion of the cell produced downwards within the area, so as to pre-
sent a horseshoe form. Edge of lamina denticulate or jagged, surface
granular. Back of polyzoary with raised radiating ridges, each of which is
more or less distinctly carivate, with a row of minute elevations on either
side of the keel.

Hab. Madeira, Johnson.

It is not improbable that this form will tw out to be
identical with the C. denticulata of Conradi, and perhaps,
therefore, with the O. Owenii, Searles Wood, of the Crag.
It is clearly distinct from the true African C. Oweniti—
1, in the conical form of the polyzoary; 2, in the horse-
shoe shape margin to the upper part of cell; and 3,
perhaps in the row of elevations on each side of the ridges
on the back of the disc. The cells also in the centre of the
disc are always completely filled up, as shown in the figure—
a circumstance which I have not observed in any specimen of
C. Owenit.

4. C. Owenii, Gray (sp.)
Hab. Madeira, Johns. ; Coast of Africa, Gray ; Fossil, Crag (?), 8. Wood.

9, P. CYCLOSTOMATA.
1. Gen. Tudbulipora.
1. 7. druidica, n. sp. Pl. XXII, fig. 9.

Crust dense, strong, thick; tubes short, upright, placed in more or less ”
distinct circles.

Hab. Madeira, Johnson.

This appears to be an undescribed form of Tubulkpora or
Diatopora, and is named from the peculiar arrangement of
the column-like tubes. The determination of the genus
must, however, be regarded only as provisional.

ZOOPHYTOLOGY.

DESCRIPTION OF PLATES.

PLATE XXII.
Fig.
1.—Scrupocellaria Delilit, nat. size.
2,— 5 », with ovicells and opercula.
3.— ee >> in older or worn condition.
4.—Cellaria Johnsoni, younger state.
5— 4, BS older.
6.—Lepralia Pouilletii.
7.— 4, discoidea, x 25 diam.
8— 4, xt x 50d.

9.—Tubulipora druidica.
10.—Eschara distoma, x 50 d.
11.—Transverse section (diagram).
12.—Nat. size.

PLATE XXIII.

1.—Cupularia Johnsoni, nat. size.

2.—Cells near margin of disc.

3.—Cells from centre of disc.

4.—Back of disc.

5.—Single cell with cuticle and vibraculum.
6.—Cupularia Canariensis, nat. size.

7.— - FS x 50d.
8.—Back.
9.—Single cell with cuticle and vibraculum.

LY TORO GY.
Plate AXII

OO

ta
ZA

WWest imp

CGBuskdelletlith

\e

e

b

&
.
2,
a
A
2,
y
y

t

LOOP ENT TOMOCL

W West ump

CBusks dele < lith

ah ad
ane cea

ORIGINAL COMMUNICATIONS.

The Rotation of CoLtourep Discs applied to facilitate the
Study of the Laws of Harmonious Cotovurine, and to
the MuutrexicatTion of Imaczs of Ossects into KaLEerpo-
scopic ComBinations. By Joun Goruam, M.R.C.S., &e.

In this paper I purpose to show how the rotation of
coloured discs may be adapted—first, to assist in the inves-
tigation of the laws of harmonious colouring, and secondly,
to the construction of combinations of perfect symmetry of
form and colour, which result from the multiplication of
images of simple patterns used as objects. Such combina-
tions are so beautiful that they may be said to vie with, even
if not to surpass, those of the kaleidoscope; and although
the principle of multiplication is different in the two instru-
ments, yet the resemblance between the figures is sufficiently
strong to induce me to designate the apparatus which pro-
duces such forms by rotation as the Kaleidoscopic Colour-
top.

The possibility of forming an apparent mixture of two or
more colours distributed on contiguous surfaces, by rotating
them rapidly on a wheel, is founded on the well-known expe-
riment of whirling a stick, ignited at one end, rapidly
round in the hand, when a continuous circle of light is at
once perceived, marking out the paths described by its burn-
ing end. As the burning extremity can only be in one point
of the path at the same instant, it is manifest that the im-
pression of its light continues some time on the eye, and an
uninterrupted circle of light is seen from the duration of
successive impressions on the retina. Coloured surfaces,
when revolved, form circular areas of colours in the same
way, and if two or more differently coloured contiguous sur-
faces are used, as many circular areas of different colours are
formed, which being superposed produce the impression of
mixture. It is obvious, therefore, that if a number of
images of different colours occupy the field of vision simul-
taneously, they will be perceived as one compound colour,
just as when plates of differently coloured glass placed in
apposition are viewed by transmitted light. The rotation ot
colours may be considered, therefore, for practical purposes,
as only another mode of mixing them.

VOL. VII. G

70 GORHAM, ON THE

The facilities of mixture afforded by this process, as con-
trasted with that of ordinary mixture, by the amalgamation
of the pigments with water or oil, are as follows: The
colours used are chosen once for all from amongst the purest
of the pigments; they are laid on circular discs of card-
board in intense washes, and thus they may be used again
and again as occasion requires. They are few in number,
because few only are required ; they are mixed im all propor-
tions evenly and smoothly with perfect ease by mere rota-
tion; they are cancelled at pleasure, even during rotation,
by scales constructed for the purpose, and they are liberated
by the same process, just as the sounds from the pipes of an
organ are stopped or unstopped by touching the keys. The
relative quantities of colour entering into given compounds,
moreover, can be expressed numerically by reference to a
scale of degrees affixed to the wheel, thus enabling us to
name a colour in reference to its constituents with some de-
gree of philosophical accuracy. It is important to notice,
however, that while the results of mixture by the ordinary
process and by rotation bear on the whole a striking resem-
blance, a remarkable exception obtains with respect to the for-
mation of green. This hue is produced in the ordinary way,
as is well known, by the union of yellow and blue in almost
any proportions; not so by rotation, for by a curious
anomaly, there is not a yellow and blue in existence, com-
bined in any proportions, that will form even a tolerable
green.

With a graduated scale enabling us to express areas of
coloured space numerically, with intense washes of pure
colours, and with a given velocity, the important problem of
a nomenclature of colours would appear to be solved; but
the known impurity of every pigment, and our inability to
produce a green hue by rotation, conspire to form an insu-
perable obstacle, and the construction of a nomenclature by
this process, although possible, must be relinquished as
useless.

The combinations by rotation serve to illustrate many of
the most interesting phenomena of colour; they furnish a
clue, for instance, to the theoretical composition of the
pigments, elucidate the principles of contrast, evoke the
complementaries, and enable us to blend colours in softer
gradations than we can by the pencil. These results are
obtained indeed with so much ease and certainty, that this
mode of studying colour might, it is presumed, be adapted
with success to educational purposes.

I propose to divide this part of the subject under the fol-

ROTATION OF COLOURED DISCS. 71

lowing heads: 1. Apparent mixture of two or more different
colours, arranged contiguously, forming hues, tints, shades,
neutrals, &c.; 2. Contrast of tone; 3. The complementary
colours; 4. Contrast of colour ; and 5. Mixture by “ soften-
ing off,” or insensible gradation.

The requisites for these illustrations are simple and si in
number. They are a rotating apparatus or colour-top ;
circular discs of white, black, green, yellow, red, and hes ;
six heart-shaped scales of the same colours ; five graduated
scales of white, green, yellow, red, and blue; and a black
double semizone.*

Here I would notice, in limine, that the colour-top should
be spun upon a table placed near the window, and when in
the act of pulling the string it should be pressed firmly
down, and not allowed to drop from a height, as is com-
monly done. The darker the rest of the room the better.
The table is provided with a cloth, light or dark in colour,
according to the experiments. These should be performed
by daylight ; the ight from a white cloud is best, then the
light from the sun as seen through a white window-blind ;
that from a blue sky is the worst kind of light that can be
chosen, hence a bright cloudless day should not be taken.

A white table-cloth is used in the following experiments.

1. On the Formation of the Hues, Tints, Shades, Neutrals,
and Grays.

The discs here employed are circles of cardboard, either
white, black, or coloured (figs. 1 to 6), and which, having a
shit cut completely through from the centre to the circum-
ference, can be made mutually to overlap one another in
sectors of any magnitude.

When sectors of two or more discs of different colours are
screwed on the colour-top and rotated, the optical composi-
tion of each colour immediately vanishes, and is replaced by
an apparent wash of one single colour only, evenly distributed
on the entire surface of the disc, and which is in reality a
combination, taking place in the eye itself, of the rays re-
flected from all the coloured surfaces employed i in the experi-
ments, thus—

(Red + blue) = violet or a violet hue.

(Red + white) = light red or a ¢int of red.

(Red + black) = dark red or a shade of red.

* The whole of the apparatus necessary to these experiments, together
with the discs for producing the kaleidoscopic effects, may be procured of
the publishers, Messrs. Smith, Beck, and Beck, Opticians, 6, Coleman
Street, London, under the title of the Kaleidoscopic Colour-top.

VOL. VII. H

72 GORHAM, ON THE

(Yellow + red) = orange or an orange hue.

(Red 30° + blue 165° + yellow 165°) = neutral.

(Yellow 15° + blue 15° + red 15° + black 315°) = brown
(see fig. 8).

(White + black) = gray, &c., &c.

2. On Contrast of Tone.

Black and white are the elements of tone; a colour be-
comes shaded or of a dark tone by mixture with black, and
tinted or of a light tone by mixture with white. The mix-
ture of white and black is gray. Grays themselves are of
different tones, varying with the relative proportions of their
elements ; hence there are dark grays and light grays. A
dark gray appears still darker when viewed in juxtaposition
with a light gray, and a light gray appears still hghter when

viewed in contiguity with a dark gray; the altered ap-
pearance of both is obviously the effect of contrast. This
may be elegantly illustrated on the colour-top by append-
ing to a circular disc of black a graduated scale of
white (fig. 7), and rotating, when a series of gray bands, ar-
ranged in concentric circles, is immediately formed. The
graduated scale is composed of segments of circles, which

ROTATION OF COLOURED DISCS. 73

continually enlarge from the circumference to the centre by
the addition of a given number of degrees (50°) in arithme-
tical progression. On careful examination of the gray zones
formed by rotating this scale on a black ground, it will be
found that each gray zone appears gradually shaded from
one of its edges, bemg somewhat lighter at its inner edge
from apposition with a darker gray, and darker at its outer
edge from contiguity with a lighter gray. These remark-
able modifications have been clearly demonstrated by M.
Chevreul.*

3. Of the Complementary Colours.

The three primary colours are yellow, red, and blue.
What is wanting in a given colour to complete this triad is
called its complementary. The complementary of red, for
example, is yellow and blue (or green) ; the complementary
of blue is yellow and red (or orange) ; the complementary of
yellow is red and blue (or violet), &c. If we gaze steadily
on a colour for a minute or so, and then direct the eye to a
contiguous gray surface, the complementary becomes visible.
These conditions are fulfilled in the following well-known
and elegant experiment. Place a black wafer on the centre
of a sheet of emerald-green paper, and over both spread a
piece of white tissue paper; the wafer no longer appears
black, but red, tinged, that is, with the complementary of
the green by which it is surrounded. “In this way colours
are actually produced by contrast. Thus, a very small dull-
gray strip of paper, lying upon an extensive surface of any
bright colour, does not appear gray, but has a faint tint of
the colour which is the contrast of that of the surrounding
surface. A strip of gray paper upon a green field, for ex-
ample, often appears to have a tint of red, and when lying
upon a red surface a greenish tint; it has an orange-coloured
tint upon a bright blue surface, and a bluish tint upon an
orange-coloured surface; a yellowish colour upon a bright
violet, and a violet tint upon a bright yellow surface. The
colour excited thus, as a contrast to the exciting colour,
being wholly independent of any rays of the corresponding
colour acting from without upon the retina, must arise as an
opposite or antagonistic condition of that membrane; and
the opposite conditions, of which the retina thus becomes the

* «The Principles of Harmony and Contrast of Colours,’ by M. i.
Chevreul; translated from the French by Charles Martel. Second edition,
pp- 7—9.

74, GORHAM, ON THE

subject, would seem to balance each other by their reciprocal
action. A necessary condition for the production of the
contrasted colours is, that the part of the retina in which the
new colour is to be excited shall be in a state of comparative
repose; hence the small object itself must be gray. A
second condition is, that the colour of the surrounding sur-
face shall be very bright, that is, it shall contain much white
lieht:? *

The required conditions are fulfilled very exactly by rota-
tion in the following experiment. Take a disc composed of
equal parts (half-discs) of white and red, and rotate; during
rotation drop down upon the spindle the black double semi-
zone (fig. 9), which will quickly revolve with the same
velocity as that of the colour-top itself; now gently breathe
upon this black zone, and when one of its rings appears of a
deep red colour the other ring will present a greenish tint ;
the greenish hue which is thus evoked, and which is the
complementary of the red, is rendered visible by being thus
thrown directly upon a contiguous gray surface. Analogous
results take place with every colour by arranging them in
the above order ; the illustrations are generally chosen, how-
ever, from green and red, as the contrasts are more palpable
to the eye, and assist in educating the uninitiated in the
perception of such delicate phenomena.

4. Contrast of Colour.

If the eye sees at the same time two contiguous colours,
they will both appear modified from their contiguity. ““When
it is asserted of the phenomena of simultaneous contrast,”
says Chevreul, “that one colour placed beside another re-
ceives a modification from it, it must not be forgotten that
this manner of speaking does not mean that the two colours,
or rather the two material objects that present them to us,
have a mutual action, either physical or chemical; it is
really only applied to the modification that takes place before
us, when we perceive the simultaneous impression of these
two colours, and which reciprocally excite each other in the
retina of the eye.”

The modifications of contiguous colours result from the
addition to each of them of the complementaries of the other.
If, for example, two narrow strips of red and orange paper
are placed side by side, in contact at their edges, and gazed

* ©Hand-book of Physiology,’ by Kirkes and Paget. Second edition,
pp. 552, 553,

ROTATION OF COLOURED DISCS. 75

on for a few seconds, the red will soon incline to violet and
the orange to yellow, for—

(Red + comp. of orange) = (red + blue) = violet ;

(Orange + comp. of red) = (orange + green) = yellow-
orange.

These effects are most apparent at those parts of the
coloured bands nearest their line of contact, and become
gradually weaker at those parts most remote from it.

The means employed to illustrate these phenomena in the
colour-top are so simple that it is almost needless to indicate
them. ‘They consist of a series of rings of colours, affixed
on differently coloured grounds, and then rotated ; an orange-
coloured ring is composed of red and yellow in equal por-
tions (see fig. 10); a violet-coloured ring consists of red and
blue in the same proportions. <A green ring should result
in like manner from equal quantities of yellow and blue; but
as this hue cannot be formed by the rotation of its elements,
an entire ring of emerald-green is used instead. A yellowish-
green is formed of yellow and emerald-green in equal parts,
and a bluish-green of blue and emerald-green. For the
grounds it is sufficient to use semi-discs of those colours
which compose them ; thus, two semi-discs of red and blue
form violet (see fig. 10) ; the shades and tints are constructed
by adding black or white, as occasion requires. When a ring
of colour is thus placed on a given ground and rotated, the
modifications from contrast may be studied with advantage,
for each colour is formed so expeditiously, that a considerable
number of illustrations may be examined without trouble or
fatigue.

5. The Blending of Colours by soft or Insensible Gradation.

When a plane, bounded bytwo similar spiral curves (fig. 12),
having its surface covered with white, black, or any colour,
is affixed to a disc of a different colour, and rotated, the
two colours appear to blend in the most delicate manner
possible, imitating to perfection that kind of mixture known
by artists as “softening off,’ and exemplified in the blush of
the cheek, the imperceptible transition from white to red
seen in the petal of the rose, the bloom on many fruits, the
golden western sky at sunset losmg itself in an atmosphere
of blue through a rich neutral, &c. Such combinations are
exquisitely beautiful. The spiral curve is thus generated :—
describe a large circle, equal in size to the circumference of
any of the discs (1 to 6), and a smaller circle near the
centre (see fig. 11). Between these two circles draw eleven
segments of circles, at equal intervals, of which the first seg-

76 GORHAM, ON THE

ment, or that nearest to the circumference, is equal to 30,
the second segment to 60°, the third to 90°, and so on to
the eleventh, adding 30° to each segment. Now join the
ends of these segments by a curved line on either side, and
the curvilinear or heart-shaped appendage is completed.
When such an appendage of pure white is affixed to a disc
of black (fig. 12) and rapidly rotated, the mixture presents
a soft transition from white to black, through an atmosphere
of gray, which is most refreshing to the eye. Many agree-
able transitions may be produced by using the white scale on
grounds of blue, green, and red, in succession. A red scale
on a ground of blue presents a most gorgeous picture—a
pure red gliding imperceptibly into blue, through every
conceivable hue of violet.

MULTIPLIED FIGURES BY ROTATION.

The Kaleidoscopic Colour-top.

When two rotating discs are used in a particular manner,
and placed in a particular position relative to each other and
the eye, they constitute the Kaleidoscopic Colour-top, or an
instrument for exhibiting beautiful forms which are similar
to those of the kaleidoscope, although essentially distinct as
to the principle on which they are constructed. Let a, for
example, be a disc having the three primary colours, yellow,
red, and blue, evenly distributed in sectors of 120° on its
surface, and let this disc be fixed to the colour-top and
rotated. Let B be a second disc, blackened on its upper sur-
face, and having a central aperture somewhat larger than
the spindle of the top, as well as a pattern of six or eight
rays cut completely through and out of its substance, so that
when held vertically over the disc a it will admit of the
colours being seen through such pattern when viewed from
above. If now the wheel is set in motion, and the dise B be
allowed to drop down upon the spindle of the colour-top,
it will be held in contact with the spindle by centrifugal
force, and will revolve in a plane parallel with the wheel, in
the same direction and with the same velocity. In this case
the colours on A appear mixed, while the pattern on B
is effaced. But if the motion of B is retarded, and at the
same time broken up into a series of rapid and regular
jerks, or more properly tsochronous vibrations, while the eye
is held vertically over the spindle, each pattern is retained
for an instant before the eye, yet sufficiently long to form a

ROTATION OF COLOURED DISCS. ae

distinct image; and owing to the rapidity of the vibrations,
a whole circle of images is thus portrayed on the retina of
the eye before the image from the first vibration is effaced.
In like manner, the colours of the disc a, which are per-
ceived only as they are transmitted through the open designs
in the disc B, appear in their primitive purity or unmixed
state, the colour in one sector being reflected through a
given ray of the pattern before the arrival of the colour from
that sector by which it is immediately succeeded. Hence,
both pattern and colours appear multiplied, thus producing
the combinations.

From the construction of the instrument, about five revo-
lutions of the disc a occur to one single revolution of the
disc 8. When these relative velocities are maintained, five
groups of all the colours distributed on the colour-disc are
seen occurring in the order of their arrangement on the
disc, and repeated in perfect symmetry in the various open-
ings of the patterns (see fig. 14, which represents a non-
rotating disc, and fig. 15, the same during rotation). In
this way the most beautiful variations may be effected by
using different colours in various proportions on the disc a ;
for however numerous the colours, each colour is reflected
through its proper opening in the disc B, at a given interval
of space and time, without the slightest irregularity or confu-
s10n.

In order to retard the motion of the dise B, and, at the

78 ON THE ROTATION OF COLOURED DISCS.

same time, to produce the vibrations, the central aperture is
made sufficiently large to admit of free motion on the
spindle ; and there is appended, at or near its circumference,
a light weight, such as a piece of string or silk, which, by its
impulses on the atmosphere during rotation, both retards the
motion and produces the vibrations. The proportion of the
diameter of the central aperture of the disc B to that of the
spindle of the colour-top is about as four to three—an
aperture of four tenths of an inch, for example, to a spindle
three tenths of an inch, is very effective.

As in the kaleidoscope, so in this instrument, there is only
one position for the situation of the eye with respect to the
discs where the symmetry of the combinations is perfect,
namely, vertically over the spindle of the top, so that the
whole of the circular field can be distinctly seen.

For the purpose of giving variety to the figures formed by
the instrument, an assortment of fantastic patterns on.
separate discs may be constructed to take the place of the
disc 8; the disc a is also furnished with different colours.
A disc of pure white forms exquisite gray combinations, with
every conceivable variety of light and shade; a disc of white
and green, in equal portions, is resolved into these elements,
and their multiplication into a composite form is very agree-
able to the eye. An elegant arrangement, whereby patterns
may be coloured in the most attractive manner, is composed
of half a disc of blue, and the rest of white, green, and red,
in equal proportions.*

The pictures thus presented to the eye are very beautiful.
Their charm would appear to depend partly upon their being
reflected to the eye through a perfectly black medium,
which imparts brilliancy and illumination to the colours, and
partly upon their being exhibited in a state of motion, the
apparent and real direction of which bear no relation to one
another. While the disc is actually performing one hundred
revolutions per minute, and vibrating about thirty times
during each revolution, the combinations themselves often
appear hanging in space, trembling without progressing, or
perfectly motionless, or gliding round in a direction contrary
to that of their real motion. These frequently recurring
and illusory changes excite the curiosity, give animation to
the pictures, and confer an ethereal brightness, vivacity, and
splendour upon them, which is altogether and peculiarly
their own.

* These coloured discs, as well as the designs already prepared on a
black ground, may be procured of the publishers, Messrs. Sinith, Beck, and
Beck.

79

Descriptions of New Srecizs of British Diatomacra, chiefly
observed by the late Professor Grecory. By Roserr
Kaye Grevitie, LL.D., F.R.S.E., &c.

Towarps the close of the year 1857, my lamented friend,
the late Professor Gregory, was engaged in the examina-
tion of some Diatomaceous gatherings, the results of va-
rious dredgings made by Professor Balfour in Lamlash
Bay. He had detected a considerable number of forms
which he believed to be undescribed; and with reference to
their publication I had completed drawings of a portion of
the series, when he was attacked by his last illness. It does
not appear that he had reduced any of his observations on
these new species to writing; at least, I have not been able
to find a single memorandum onthe subject. So that, how-
ever desirous I may be to secure to the name of my late
friend the credit due to his discoveries, I fear that, even
with the aid of his collection, which has been most kindly
presented to me by his widow, I shall perform this duty
very imperfectly. It unfortunately happens that, in some
cases, the slides which contained the objects to be drawn
were returned to him for description, and I have neither
been able to find the original slides (in the absence of any
distinctive mark or label), nor additional examples of the
forms in question. The present communication consequently
does not contain a notice even of all the species of which I
had made drawings. The wonderful memory possessed by
Professor Gregory rendered him independent of temporary
notes. The careful study he bestowed upon the forms which
came under his eye, fixed every character, however minute,
in his mind, and it was not until he had completed his
investigations that he sat down to record them. By his
death Science has lost a most successful explorer, as well
as one of the most patient and indefatigable of microscopic
observers.

1. Cocconeis pinnata, Greg. MSS.

Valve oval; striz concentric with the extremities, robust,
moniliform, distant, not reaching the median line, but leaving
a narrow-elliptical blank space; length ‘0014; strize 11 in
O01" (Pl. VI, figs hh)

Marine. Lamlash Bay, in the Island of Arran. Dredged
by Professor Balfour in 1857.

Among the new forms detected by Professor Gregory in

VOL. VII. I

80 GREVILLE, ON DIATOMACE.

the Lamlash Bay gatherings, were two or three species of
Cocconeis ; and I find that, in his correspondence with our
mutual friend, Mr. Norman, of Hull, he referred to two of
them under the provisional names of pinnata and crassa.
Of the latter I have as yet discovered no trace; but, with
regard to the former, although I have no certain clue to
guide me, I think I may safely venture to assume that the
form now described is the one so named by him. It is
a beautiful little species, well distinguished by the short,
strong, moniliform, distant strie, and by the narrow-elliptical
blank space which longitudinally occupies the middle of the
valve. I have the drawing of another apparently new and
fine species, but the slide containimg it was returned, and I
have been unable to find it.

2. Cocconeis arraniensis, Grev.

Valve oval; strize concentric with the extremities, slender,
faint, moniliform, contiguous, reaching to the median line ;
length :0016” ; strie 30 in ‘001”. (Fig. 2.)

Marine. Dredged in Lamlash Bay, by Professor Balfour,
1857.

In working through some of Professor Gregory’s slides,
this minute and inconspicuous form attracted my attention.
It appears to be undescribed, and I do not know any
species with which it is at all likely to be confounded.
Under a moderate power of the microscope it is difficult to
distinguish its structure satisfactorily. Compared with other
species of the genus, the moniliform striz are slender and faint;
and,in consequence ‘of their being g placed close together, the eye
is caught as much by the sharp lines caused “by the juxta-
position of the striz, as by the striz themselves; and it is
not until a higher power is used that the structure is
cleared up.

3. Coscinodiscus Normanni, Greg. MSS.

Areolation forming numerous fasciculi of radiating lines
or rows of areole, each fasciculus composed of about six
rows ; areolz equal, except at the margin, where they become
suddenly smaller and faint; margin smooth; diameter of
dise ‘0016” to -0036” ; areole about 24 in 001”. (Fig. 3.)

Marine. In the stomach of Ascidians, Hull. George
Norman, Esq.

Professor Gregory’s attention was first directed to this
Diatom by Mr. Norman, who obtained it, as well as many
other interesting species, from the stomachs of Ascidians.
Believing it to be new, he bestowed upon it the name of its

GREVILLE, ON DIATOMACEA. 81

discoverer,—a well-merited compliment. Mr. Norman had
also, in 1856, obtained abundant specimens of a Coscinodiscus-
like Diatom, by washing the mud which adhered to the
roots and stems of Dutch rushes imported into Hull from Hol-
land. This last form was doubtfully regarded by competent
observers as Coscinodiscus subtilis of Ehrenberg; and as the
question arose, whether the two forms above referred to
were not identical, I have been necessarily led into an
examination of the history and characters of C. subtilis.
The species was first described by Ehrenberg, in his ‘ Essay on
the Microscopical Organisms of South and North America ;’
and the localities he assigns to it are Peru and Vera Cruz.
But of the two figures which he gives (tab. I, iii, fig. 18,
and tab. III, vu, fig. 4), the second, that of the Vera Cruz
form, is accompanied with a mark of doubt; and it must be
confessed that the figures are most unlike each other.
Kiitzing, in his ‘ Bacillarien,’ merely repeats Ehrenberg’s sta-
tions, and adds another representation, which, again, is too
indefinite to be depended on; nor does he afford any addi-
tional information in his ‘Species Algarum.’ The late Professor
Bailey, of New York, however, who was in direct communi-
cation with Ehrenberg, found in 1850, im various districts in
the United States, a Coscinodiscus, which he named, without
hesitation, swbtilis of that author. In the earth of the rice
fields of Georgia, particularly, he discovered it in vast
abundance, and expressed his surprise, that it, and a large
proportion of the forms which accompanied it, were such as
only inhabit salt or brackish water ; indicating the presence
of salt water much further up the rivers than it now extends.
(‘Microscopical Observations made in South Carolina, Georgia,
and Florida.’)

Lastly, Ehrenberg, in his ‘ Mikrogeologie’ (1854), extends
the geographical distribution of the species very consider-
ably, giving the following list of localities, with a figure to illus-
trate each: Canton, China, tab. XXXIV, vu, fig. 6. Sicily,
tab. XXII, fig. 4. Richmond, Virginia, tab. XVIII, fig. 35 ;
and tab. XX XIII, xvi, fig. 7. Assistance Bay, North Pole,
tab. XXXV, xxii, fig. 5. South Pole, tab. XX XV, xxii, fig. 5.
California, tab. XX XITI, xin, fig. 4. It is much to be regretted
that none of the above-mentioned illustrations are charac-
teristic ; and they appear, besides, to differ very considerably
from each other. Nevertheless, we may, I think, assume
with some confidence, that the American form is the true
C. subtilis. If we now compare this with the Coscinodiscus
discovered by Mr. Norman, in the stomach of Ascidians, we
must admit that, at first sight, the two species greatly

82 GREVILLE, ON DIATOMACEA.

resemble each other. On closer observation, however, cer-
tain differences do constantly present themselves. In both,
the most strikmg character is the beautiful radiation, which
Professor Gregory aptly compared to that exhibited in the
stars of some orders of knighthood. The lines thus formed
by the areolation are grouped into what, in the absence of a
better term, may be called fasciculi, and they appear to con-
stitute a good discriminative character. In the Hull disc,
these fasciculi, as they become well defined in their approach
towards the margin, are composed of about six rows of
areolz ; in the American disc, on the contrary, the fasciculi
contain double the number of rows, and are themselves, con-
sequently, proportionably less numerous. The line of separa-
tion between the fasciculi is also more evident, causing the
appearance, under a low power, of a slight undulation of the
surface, which effect is heightened by the straight oblique
rows of the more regular areole. If the margin be brought
into focus, the superior regularity of the areolation becomes still
more apparent in the series of little intersecting arches which
spring, as it were, from the inner edge of the border. These
differences, not very great perhaps in themselves, yet arising,
as they must do, from the structure of the valve, incline me
to regard the two forms as distinct.

With regard to the disc found on the “ Dutch rushes,” I
cannot speak with certainty. No doubt the general character
of the areolation (including the radiating fasciculi) is very
similar to that of C. Normanni. But Mr. Norman has
pointed out to me the fact (which I have also since observed
myself) that frustules in a state of union present, on the
front view, a decided undulation, indicating, in this respect,
some affinity with Cyclotella punctata. Sm. Syn. V, 2, p. 87,
a fresh-water species.

In the centre of the dise of C. Normanni may be gene-
rally perceived a small irregular, interrupted, opaque circle ;
as if there were either minute prominences of some extra-
neous matter, or as if some of the areole were filled with it.
But this appearance is not invariably present. It is most
conspicuous under a low magnifying power.

Having found it difficult to convey a correct idea of the
structure by means of a figure on the usual scale, I have
enlarged the one given in the plate x 800 diameters.

4. Nitzschia arcuata, Greg. MSS.

Front view of frustule linear, arcuate, rounded at the
ends; side view lanceolate, obtuse ; length ‘0038’; puncta,
about 20 im ‘001. (Figs, 4—-7.)

GREVILLE, ON DIATOMACE. 83

Marine. Dredged in Loch Fine, by Professor Gregory,
1856. Lamlash Bay, Professor Balfour, 1857. In a
dredging made the same year, off Invercloy, in Brodick
Bay, by the Rev. Dr. Miles; Professor Walker-Arnott.

A very characteristic species, not to be confounded with
any of the genus already known. It appears to be both
local and rare, as it occurs in only two of the numerous
Arran gatherings.

5. Nitzschia macilenta, Greg. MSS.

Frustule linear, slightly sigmoid, truncated; side view
linear, slender, gradually tapering towards the acute
extremities, keel with a single row of sub-remote puncta;
strie very obscure; length -0150” to 0190"; breadth -0004”
to 0007"; puncta about 8 in 001”. (Figs. 8, 9.)

Marine. Lamlash Bay, dredged by Professor Balfour, 1857.

A fine species, evidently allied to N. sigmoidea, but de-
cidedly less sigmoid. The side view is very narrow. The
puncta are separated from each other by irregular intervals,
and are fewer than in N. sigmoidea. The striz I have not
succeeded in resolving, nor was Professor Gregory more suc-
cessful. It is undoubtedly a marine species, and tolerably
frequent in one of the Lamlash gatherings.

6. Navicula forcipata, Grev.

Valve oval or oblong, marked by two continuous longitu-
dinal linear blank spaces, which contract opposite the nodule,
and then expand and converge concentrically towards the
extremities, where they almost meet; length -0013” to
"0030"; striz 35 im 001". (Figs. 10, 11.)

Marine. Glenshira sand, Professor Gregory. Lamlash
Bay, dredged by Professor Balfour. Cresswell, Northumber-
land, Dr. Donkin. Californian guano.

After a very careful examination of this little Diatom, I
entirely agree with Professor Gregory in regarding it as un-
described. The examples which fell under his observation
were very inferior to those which I have recently obtained,
which accounts for his bemg led to compare the form with
Navicula pygmea. The finer specimens show that it is more
nearly related to N. Lyra and N. spectabilis, as will be seen
at once by consulting the figures. It must indeed be con-
fessed that large individuals at first sight seem to approach
very near to some small varieties of N. Lyra. Iam, however,
satisfied that the two species are really distinct. Perhaps
the characters most to be depended on im our new form are
—1l. The greater number of striz, about 35 im -001”; while

84 GREVILLE, ON DIATOMACES.

in N. Lyra they are, according to Professor Smith, only 20
in*001" (rather under the mark according to my estimate).
2. The invariably converging points of the blank spaces. I
may add, in addition, that there is a striking flatness in the
value of N. forcipata ; and that the blank spaces are defined
by hard, sharp lines of contour, caused apparently by an
abrupt depression in the surface of the valve. This is so
conspicuous, that, under a moderate magnifying power, the
eye dwells rather on the two parallel dark lines than on the
blank space they enclose. The general outline, also, of the
valve is not variable, as in N. Lyra, being never, as far as I
have seen, produced at the ends, but always presenting an
uninterrupted symmetrical curve. The Northumberland
examples are the finest which have come under my notice;
those from the Clyde are, for the most part, much smaller,
—many of them even minute,—thus exhibiting a range of
size as extensive as in N. Lyra and its allies.

7. Pinnularia semiplena, Grev.

Valve linear-elliptical, subacute; cost radiate, distant,
very short in the middle, and becoming gradually longer
towards the extremities, leaving an elongate, lozenge-shaped,
centrical, blank space; length ‘0024; breadth about ‘0006" ;
coste 15 in ‘001", (Fig. 12.)

Navicula angulosa, var. B. Greg. ‘Trans. Mic. Soc.,’ v. iv,
p. 42, Plate V, fig. 8*,

Marine. Glenshira sand, Professor Gregory. Lamlash
Bay, dredged by Professor Balfour.

Having had abundant opportunities of observing this form,
especially in my recent examination of many of Professor
Gregory’s slides, I feel quite convinced that it is distinct from
Navicula angulosa. 1 have not seen any approach towards
an intermediate state. Indeed, I do not know any species
more constant in regard to size and every other character.

8. Achnanthes gregoriana, Grev.

Front view of frustule broadly linear; striz very fine ;
length -0060" to 0080"; breadth -0010" to 0015". — (Figs.
13, 14.)

Marine. Lamlash Bay; dredged by Professor Balfour,
1857.

Although a considerable number of the scattered frustules
of this species have occurred both to Professor Gregory and
myself, no other view than the one represented in the plate
has been observed. In point of size it rivals A. longipes, but

GREVILLE, ON DIATOMACES. 85

is widely separated from it in the character of the striation
alone, to perceive which, requires not only a good object-
glass, but delicate manipulation. As im many of its con-
geners the frustules vary greatly in both length and breadth.
In Canada balsam they become so transparent as to be easily
overlooked. A. gregoriana must be accounted rare, for
among the many dredgings and gatherings which have been
made in Lamlash Bay and its immediate neighbourhood, one
alone, so far as I know, contains it ; nor is it abundant even
in that, as seldom more than three or four examples are found
to occur in a slide. At the same time, there is every reason
to conclude that its habits must be similar to those of the
other species, and that a diligent search along the coast
might be rewarded by its discovery in a living state—para-
sitic probably on other Algz.

9. Podosira levis, Greg. MSS.

Filaments composed of two (?) frustules, which are pale
yellowish, transparent, glassy, somewhat compressed at the
poles, very delicately and obliquely striated, and remotely
and very finely punctate; cingulum firmly siliceous, distinctly
striated ; diameter of frustule ‘0018” to 0021". (Figs. 15,
17.)

Marine. Lamlash Bay; dredged by Professor Balfour,
1857.

This conspicuous, although minute little Diatom, was con-
sidered by my late friend, Professor Gregory, as a Podosira,
and a few specimens, I believe, were distributed by him
under the name now adopted. Like P. Montagnei, the fila-
ments are probably composed of only two or three frustules ;
but none of the numerous discs or loose valves which I have
examined, exhibit any indication of the absence of silex, or
even of imperfect siliceous structure at the apex of the valves.
Some doubt may therefore be entertained regarding its
true generic position. The structure, when carefully exa-
mined under a good objective, is very beautiful, being
singularly glassy and brilliant, and most delicately striate
and punctate; characters best seen in the dry-mounted slide.
In balsam they are not readily perceived. The puncta are
equally scattered over the whole frustule, and resemble ex-
cessively minute prominent glands. The peculiarly brilliant
manner in which the frustules transmit the light renders
them conspicuous objects in the field of the microscope. The
species appears to be scarce, having been observed, like the
preceding one, in a solitary gathering. From three to half a
dozen frustules not unfrequently occur in a slide; but very

86 ALLMAN, ON APPENDICULARIA.

rarely accompanied with the cmgulum. In this case, again,
we may look forward with some confidence to its being found
in a living state, parasitic on some of the smaller sea-weeds.

On the Pecutian Apprenpace of Apprnpicuarsa, styled
“Haus” by Mertens. By Prof. Artman, F.R.SS. L. &. E.

(Read at the Royal Society of Edinburgh, December 6th, 1858.)

WHILE using the towing-net in the Clyde, near Rothesay,
during the last week of April, 1858, I observed among the
contents of the net numerous specimens of an Appendicu-
laria, which I cannot, without some doubt, refer to any
described species, but which I shall not at present venture
to name as distinct, for my attention was at the time rather
turned to other poimts in its economy than to the determi-
nation of its specific characters.

In no one instance did any of these specimens present
traces of the remarkable appendage described by Mertens
under the name of “haus,”* an appendage hitherto never
witnessed by any naturalist save Mertens himself. The day,
however, was bright and the water smooth, and while looking
into the sea over the side of the boat, my attention was
arrested by some singular bodies swimming at the depth of
a few inches below the surface.

With these bodies I was altogether unacquainted, and my
efforts were accordingly at once directed to the capturing of
some of them. In this I soon succeeded by means of a —
basin carefully introduced beneath them, and to my great
pleasure I found that I had the identical species of Appen-
dicularia just taken in the towing-net, but now invested
with a most singular and elegant appendage, which was
easily recognised as the “haus” "described nearly thirty
years ago by Mertens as occurring in specimens of Appen-
dicularia taken by him in the neighbourhood of Behring’s
Straits, and never since seen, though thousands of indi-
viduals of different species of this genus had fallen under the
observation of such able investigators as Miller, Huxley,
Leuckart, and Gegenbaur.

There was no difficulty, however, in perceiving how it was

* »Mém. de l’Acad. Imp. des Sc. de St. Petersbourg,’ 1831.

ALLMAN, ON APPENDICULARIA. 87

that these naturalists had never got a sight of so remarkable
an object, for I soon found that it required the greatest
possible care to prevent its detaching itself; and that, even
with every precaution, it remained but a very short time after
capture in connexion with the body of the Appendicularia.
The irritation caused by transferring the contents of the
basin into a glass jar for more effective examination caused,
in most cases, its separation, and it was only in very few
instances that Isueceeded in bringing home a perfect specimen.
Even then I had generally the mortification of seeing the active
Appendicularia break away from its “haus” almost imme-
diately after arrival ; and when it is further borne in mind
that the separation of this appendage is almost instantly
followed bv its collapse, and by the consequent losing of all
its most striking characters, the difficulty attending its exami-
nation will be easily conceived.

To transfer the animal in a perfect state into a small
trough for investigation under the compound microscope was
impossible, and I was therefore obliged to keep it in a large-
sized glass jar, and content myself with such observations as
a simple hand-lens would enable me to make.

A correct idea of the “haus” of the present species of
Appendicularia may perhaps be best obtaimed by imagining
a clear gelatinous oviform body, which in full-sized specimens
has its greaterdiameter about five lines inlengthand its smaller
about four (Plate VI). That plane of the greater diameter
which passes vertically through the body of the animal will
divide the “ haus” into a right and a left half, and the
common plane of any two lesser diameters will divide it into
an anterior and posterior half.

Within the gelatinous mass, and chiefly occupying the
anterior half, are two remarkable structures, each shaped lke
a double fan, whose general form may be best understood by
imagining a semicircular membranous lamina to be folded
upon itself along a line uniting the middle points of its
curved and straight margins. There will thus be formed a
double fan, constructed of two single fans, united along one
edge, but open along the other two. The two double fans
thus constituted are situated symmetrically in the gelatinous
mass, to the right and left of its greater diameter, their bases
or convex edges being directed towards its surface, and their
apices nearly meeting one another at a point in the greater
diameter a little in front of the centre, while their axes (a
line drawn from the apex to the centre of the base) will he
nearly in the horizontal plane passing through the greater
diameter. The closed edge is directed forwards and inwards,

88 ALLMAN, ON APPENDICULARIA.

the open convex edge or base outwards, and the remaining
open edge backwards and inwards.

The convex edge of each fan nearly reaches the surface of
the gelatinous mass, to which it then runs almost parallel,
extending forwards upon each side to within a short distance
of the anterior extremity of the greater diameter, and back-
wards to a point nearly opposite to the junction of the
posterior and middle third of this diameter.

The surface of each of the double fans is marked with
numerous regular corrugations, apparently formed by folds
of the membrane, which converge from the whole of the
convex margin towards the apical angle where they gradually
die out.

Towards the convex margin the fans are colourless and
transparent, but towards the apex they lose their transpa-
rency and assume a light-yellow colour.

About midway between the apices of the fans and the
posterior extremity of the greater diameter, and in a vertical
plane passing through this diameter, is situated the body of
the Appendicularia. So far as I could make out it seems to
be simply imbedded in the gelatinous mass, having its respi-
ratory aperture directed towards the apex of the fans, while
its tail alone is free, and by the constant vibrations of the
latter the whole structure is carried about through the sur-
rounding water.

On each side of the spot in which the body of the Append-
icularia 1s imbedded the gelatinous investment presents an
elliptical superficial patch of a yellowish colour, to which
there invariably adhered Naviculze and other minute bodies,

Beyond the poits now described in this most curious
appendage I have not succeeded in detecting any other
structure ; no trace of the vascular network described by
Mertens was observed, and we must assuredly deny the
respiratory function ascribed to the appendage by its original
discoverer. I must also add that I never witnessed its re-
newal after destruction, which Mertens mentions as occurring
within so short an interval as half an. hour.

A comparison of the body described in the present com-
munication with that noticed by Mertens will show that,
besides the total absence of the vascular network, it differs
considerably in detail from the corresponding appendage of
the Behring’s Straits specimens. In these it is considerably
larger than in the specimens from the Clyde, while Mertens
describes and figures under the name of “ horns’ two pairs
of folded laminz, represented in the present species by the
single pair of fan-like structures; and the shape of these, in

WALKER-ARNOTT, IN REPLY TO DR. DONKIN. 89

Mertens’ species, differs considerably from that of the fans in
the present one. Still there can be no doubt that the
“haus” of Mertens is the exact equivalent of the body now
described, and the differences seem to be merely traceable to
a difference of species.

If I might offer an opinion as to the real import of the
“haus,” I would suggest the probability of its being a de-
finitely shaped secretion, destined to act as a nidamental cover-
ing for the ova. I do not wish, however, that this sug-
gestion should be taken for more than it is worth, for it is
chiefly based on the circumstance that it is difficult to offer
any other explanation, and on the fact that in one instance
I found numerous minute and evidently young, though nearly
fully developed, Appendicularie immersed in the gelatinous
mass of the haus. Beyond this I shall not venture even a
guess at its physiological or morphological significance.*

Dr. WaLKER-ARNoTT, in Repiy to Dr. DonkIN.

In the last number of the Journal appeared an article
purporting to be a reply to me by Dr. Donkin, but which
contains, in fact, a repetition of some observations respect-
ing Ampiphrora Ralfsii, published by him in the ‘ Transac-
tions of the Microscopical Society’ in January, 1858, p. 33.
I allude more particularly to what he erroneously states
with regard to the name of Amphiprora Ralfsti being mine
generically as well as specifically.

It might be sufficient to indicate that I communicated
the specific name to Mr. Ralfs; that Dr. Donkin’s infor-
mation was not obtained from me, but must have been
derived directly or indirectly from Mr. Ralfs; and that every
one acquainted with Mr. Ralfs’ writings knows that his

* The above account was drawn up immediately after the observations
which it records were made. I however delayed its publication under the
expectation that I might have an opportunity of obtaining fresh examples
which would enable me to supply some of the many deficiencies which exist
in it. No such opportunity has since occurred, and I have, therefore, not-
withstanding its imperfect form, thought it better to publish it as it is, with
the hope that it may be of some use in enabling other naturalists to render
more complete our knowledge of a structure which at best is highly enig-
matical. Dr. Strethill Wright, of Edinburgh, informs me that during the
autumn he obtained in the Frith of Forth specimens of an Appendicu-
aria invested with its “haus.”

90 WALKER-ARNOTT, IN REPLY TO DR, DONKIN.

sentiments are thus expressed (‘ British Desmidiacee,’ Pre-
face, p. vi): “the name appended to a species merely in-
dicates the author of the specific name, and has no reference
to its genus.” But as this would hardly be enough, I am
compelled, in self-defence, to allude to some antecedents
with which the public have otherwise no concern.

Mr. Ralfs, in September, 1857, sent me a slide, prepared
in balsam, of what he supposed to be ‘ Amphiprora
didyma” of Smith. In it I did not detect the F.V.,
nor could I observe distinctly the carmation of the valve
characteristic of Amphiprora; and, m my reply, I gave my
opinion that it was a Pleurosigma, and, if so, that it might
prove a broad variety of P. obscurum. In his next letter
(early in October), he says most justly, that “ the front view
is very unlike a Pleurosigma,’ and that he was not aware
of any Pleurosigma having the F.V. constricted, or being
as broad or broader than the 8.V. In consequence of re-
ceiving also from Mr. Ralfs some of the material in a tube,
and being thus enabled to study its F.V. as well as 8.V.,
I readily acknowledged the force of Mr. Ralfs’ objections to
its being a Pleurosigma. But while I yielded on that point, I
egaxl not consent to its being 4. didyma, unless Professor
Ssuitb or the printer had made a great mistake as to the
strie; and as I understood that Mr. Ralfs was about to
publish it as an Amphiprora in the forthcoming edition of
Pritchard’s ‘ Infusoria,’ I proposed to him to allow me to
name the species after himself.

The name of the species, therefore, was mine; the merit
(or, in Dr. Donkin’s estimation, the demerit) of its being
referred to Amphiprora rested with Mr. Ralfs, and on the
numerous accurate observations he had made on it when
recent and in motion. It was not until December, when
preparing my notice on Rhabdomena for the Journal of
January, 1858, that, having an opportunity, and wishing to
obviate the apparent indelicacy of Mr. Ralfs being the first
to publish the name Ralfsii, I revised the subject with
greater care, and drew up a diagnosis sufficiently explicit
for all who are conversant with such topics, and so general
as to include several forms. Then only could it be said that
I was responsible for the genus; but, even then, only in the
same way that Smith is responsible for the genus of Amphi-
prora alata or constricta, these having been previously
referred to that genus by others. Dr. Donkin’s remarks
appeared in the same number of the Journal, and seem to
have been penned before I myself had formed a decided opinion
on the point, and at a time when I was no way responsible

WALKER-ARNOTT, IN REPLY TO DR. DONKIN. 91

for the generic name. Had he wished to ascertain the facts
of the case, he could have applied to me previously, instead
of receiving his information second-hand from others, whether
by letters, or by slides which I had not examined or named. In
my reply to him, at p. 196, I stated my belief that, had he ap-
plied to me, the paragraph would not have been written: al-
though he has had ample time since then to obtain from me pri-
vately full information, he has preferred repeating the mistake.
He now introduces Dr. Montgomery’s name ; in consequence
of which I considered it proper to apply to that gentleman
for an explanation. His answer (6th November) is quite
satisfactory and explicit: “I am exceedingly sorry that Dr.
Donkin has made a mistake about A. Ralfsii. In my letter
many months ago, I gave him distinctly to understand that
merely ‘ Ralfsi’ had been suggested by you.” It only therefore
remains for me to state that Dr. Donkin’s attribution of the
‘generic appellation to me was without foundation ; and now
to close this very disagreeable discussion into which I have
been forced against my wishes.

On the Caucarteous Corpusciss of the TrEMatopa; and on
the GENUS Terracotyte. By HE. Cuaparepe, of Geneva.

(Siebold and Kolliker’s ‘ Zeitsch. f. w. Zool.,’ vol. ix, p. 99.)

Tuer calcareous corpuscles of different entozoa have fre-
quently attracted the attention of observers. For a long time
regarded as ova, their calcareous constitution was at length
recognized, and at present they are universally looked upon
as an earthy deposit in the integument. Siebold, for instance,
compares them with the calcareous bodies found in the in-
tegument of the Holuthuriz and in the soft parts of many
polypes. I have, however, for some time, been aware that
these corpuscles, in some Trematoda at any rate, have a cer-
tain relation to the excretory apparatus. This observation
was first made in April, 1855, in Diplostomum rachieum,
Henle, from the spinal canal of the Frog. In this instance,
it was obvious at first sight that a minute vessel proceeded
from each corpuscle. Closer examination showed that each
corpuscle is contained in a capsule fitting pretty closely
around it, and whose wall is continuous with that of the
tubule. Several of these vessels unite into a single branch,
which communicates again with one of the ramifications of
the excretory system. This system in D. rachieum is con-
stituted of a slender, gradually enlarging trunk, which runs
from behind forwards in the middle line of the body, and
is connected, at the anterior extremity of the animal, by
a branch on either side, with the lateral trunks. The latter
descend nearly parallel with the border and, gradually en-
larging, open at the hinder end into the two-pointed
contractile vesicle. From each of these three main trunks
numerous vibratile vessels are given off; and besides these
they are connected with each other by numerous transverse
branches; one of which, in particular, may always be re-
marked passing across immediately in front of the abdominal
acetabulum. As is well known, Leydig* has regarded this
excretory system as a ramified intestine, considering, on the
other hand, the true intestine as a bifureate excretory ap-
paratus.

ach ramuscule terminates ciecally, becoming expanded
ito an oviform vesicle, uniformly occupied by a calcareous
corpuscle. These bodies, however, are never met with in the

* «Zeitschrift fir Wissensch. Zool.’

CLAPAREDE, ON TREMA'TODA, ETC. 93

main trunks or in the course of the vibrating vessels. Occa-
sionally, individuals may be noticed presenting no corpuscles,
which may be owing to the circumstance either that they
were never formed, or that they had been discharged. The
oviform enlargements of the vessels, however, always exist.

Having made this observation, I had the pleasure of satis-
fying Johan. Miiller, Dr. De la Valette, Professors Weinland
and Lachmann of its correctness ; and more recently I have
had the satisfaction of showing the connexion between the
calcareous corpuscles and the excretory system to Professor
Virchow.

Dr. De la Valette thinks he has observed minute twigs
given off from the oviform sacs, but of this I have been
unable to satisfy myself.

In Diplostomum rachieum it is so easy to perceive that the
calcareous corpuscles are situated within the excretory sys-
tem, that it is surprising this relation has not been earlier
noticed; but its occurrence in this case having been esta-
blished, it naturally suggested itself to suppose that a similar
condition was not limited to D. rachieum, but would also be
found in other Trematoda. The first to be examined were of
course other species of Diplostomum. Diplostomum volvens,
and D. clavatum from the lens and vitreous humour of several
fresh-water fishes, were examined, and afforded the expected
results. The excretory system in these two species having
been sufficiently described by Nordmann,* it is only neces-
sary to remark in addition, that in them also the vessels
terminate in globular dilatations and enclose the corpuscles.
In the three species of Diplostomum examined, one particular
part of the body was found especially adapted for the exhi-
bition of the condition in question—the region, viz., behind
the hindermost acetabulum. In this situation the corpuscles
are only sparingly distributed, and the connexion between
the cavities containing the corpuscles and the vessels is
readily seen when the animal is quiescent.

The calcareous corpuscles of the Diplostomata are thus in
all respects similar to those which are found in the main
trunks of the excretory system in many Cercarie and certain
Distomata. 1 am unable therefore to agree with M. Moulinié+
in viewing the two kinds of corpuscles as distinct from each
other. According to this author, the corpuscles which occur,
as he thinks, not in the vascular system but in the paren-

* ‘Micrograph. Beitrige zur Naturgesch. der Wirbellosen Thiere,’
p. 37 ef seq.

+ ‘ De la reproduction chez les Trématodes endo-parasites.’ Genéve, 1816,
p. 223

94. CLAPAREDE, ON TREMATODA, ETC.

chyma of the animal, would appear to represent the first
stage of a process of calcification. They are regarded by
him therefore as a pathological product; but I see no reason
for looking upon them in any other light than as being alto-
gether normal.

Upon my communicating, a short time since, to Dr. G.
Wagener, my observations on the calcareous corpuscles of
the Diplostomata, he told me that he had been long acquainted
with their relation to the excretory system, but that he had
not made it known; showing me also some drawings of the
appearances he had observed. At the same time he en-
couraged me to investigate other species. The first subjects
which suggested themselves were the immature forms of
Holostoma, the Diplostomata themselves being manifestly
nothing more than Holostomatous larve. Steenstrup had
already pointed out the relationship between the Holostomata
and the Diplostomata, and propounded the view that Diplo-
stomum clavatum, Holostomum cuticola, and Diplostomum
volvens are one and the same species, of which the two
former would represent the immature, and the latter the
mature animal. But this association appears to be the less
maintainable since Diplostomum volvens is as much an im-
mature form as Diplostomum clavatum. Nevertheless, it is
indubitable that the mature forms of these various ani-
mals must belong to the genus WHolostomum. Several
immature Holostomata are, as is well known, characterised
by a network composed of calcareous corpuscles disposed in
regular order in the integument, as for instance Holostomum
cuticola. As the latter species was not at the moment ob-
tainable, I directed my attention in the first stance to some
Trematode-cysts from the peritoneum of the Stone-Perch
(Acerina cernua). The cysts, of an oval form, were about
0°50—O0°60 mm. in length, and easily lacerable. The animal
contained in them, presented in many respects an unmistake-
able resemblance to the Holostomum-type, though differing
considerably in several points. The excretory system con-
sisted of two principal trunks running down each side of the
body, and opening into a double contractile vesicle, closely
resembling that of Diplostomum volvens. These lateral
trunks were of extraordinary dimensions ; so that the internal
organs were separated by a wide interspace from the wall of
the abdomen; they presented a chambered or moniliform
appearance, owing to the circumstance that numerous bands
proceeded from the external wall of the body to the internal
organs, and served to retain them in their situation. The
lateral trunks were filled with minute calcareous particles.

CLAPAREDE, ON 'TREMATODA, ETC. 95

which were kept in continued motion backwards and forwards,
and they also gave off branches which went to form a net-
work in the anterior and lateral parts of the body. The calca-
reous corpuscles were lodged in these branches, and were not
unfrequently pushed into the lateral trunks. No ciliary move-
ment could be perceived in the vessels. In this case there-
fore no doubt can be entertained that the corpuscles are
lodged in the excretory system, and that the arrangement is
precisely lke that which is witnessed in the Holostomata
with a plexiform disposition of the calcareous corpuscles ; as,
for instance, in Holostomum cuticola. The calcareous cor-
puscles exhibited great diversity of aspect. Some were per-
fectly homogeneous ; others presented a distinct concentric
structure; whilst others again consisted in reality of several
corpuscles united by a common enveloping calcareous layer.
There were sometimes noticed in the lateral trunks, cell-like
bodies, enclosing calcareous corpuscles and minute particles.

With respect to the chemical composition of the so-termed
calcareous corpuscles of the Trematoda and Cestoda we at
present possess very insufficient information. In Echinococcus
veterinorum, Huxley* asserts that they consist at first of an
albuminous substance, but that they may afterwards become
cretified ; a statement which is disputed by Leuckart.t I
should not be disposed at once to reject Huxley’s view, seeing
that the chemical composition of the corpuscles differs im
different species, and it is very possible that it may vary
according to circumstances In one and the same species. At
any rate, the organic substance which serves as a matrix to the
inorganic constituent, greatly predominates. The corpuscles
in Diplostomum rachieum, volvens, and clavatum appear at
first sight to be dissolved by caustic potass. This appearance,
however, depends simply upon the circumstance that they
are rendered transparent by that reagent, the transparency
gradually advancing from the periphery towards the centre;
the refractive power of the corpuscles is considerably increased,
but in other respects they remain as before. This change
obviously depends upon the solution of the organic matrix
by the potass. The incrusting matter In some animals is
always carbonate of lime, as for instance in Diplostomum
rachieum, Echinococcus veterinorum, Trienophorus nodulosus,
&c.; but in others, as in Diplostomum volvens and clavatum,
I have been unable to detect any carbonate of lime in the
corpuscles, which in these cases are dissolved in acids without
effervescence. It is possible that in these instances the

* «Annals and Magazine of Nat. Hist.,’ 2d series, vol. xiv, p. 381.

+ ‘Die Blasenbandwiirmer.’ Giessen, 1856.

VOL. VII. K

95 COHN, ON NASSULA ELEGANS.

incrusting material is phosphate of lime. The concentrically
laminated corpuscles of Distoma nodulosum are soluble in
acids without effervescence; the solution, on the other hand,
being preceded by a swelling up of the substance, so that the
presence in them of phosphate of lime can hardly be supposed ;
the swelling being due solely to the organic basis. It has
already been remarked by Ktichenmeister, that the so-termed
calcareous corpuscles in Tenia solium, and denticulatum,
Bothriocephalus latus, punctatus, and claviceps, dissolve in
acids without effervescence. From this it is evident how
insufficiently the true nature of these corpuscles in the
‘Trematoda and Cestoda has been investigated. It is a point,
however, well worthy of investigation, since the accurate
knowledge of the chemical conditions of these bodies is cal-
‘culated to throw a clearer light than we yet possess upon the
function of the excretory system.

[M. Claparéde’s paper, besides his observations upon the
**Calcareous corpuscles,” contaims some upon the relations of
the animal found in the Trematode-cysts from the Stone-
Perch, ‘and which is regarded by him as belonging to the
genus Tetracotyle of Filippi—to the Distomata and Cestoid
worms. He expresses the opinion, that Tetracotyle, like
Diplostomum, represents a division of an immature Trematode,
and that it appears very probable that the corresponding
mature forms are to be sought among the Holostomata.]

On the Repropuction of Nassuta Evecans (Ehr.) By Dr.
Frerpinanp Coun, of Breslaw.

(Siebold and Kolliker’s * Zeitsch. f. w. Zool.,’ vol. ix, p. 143.)

AxutuoucH the reproduction of the Infusoria by a motile
internal progeny (schwiarmsprésslinge) is well established
m the case of several species, the number of forms in
which the production of endogenous embryos has been
observed is so limited, that we are not at present justified in
expressing a decided opinion as to the universality of this
mode of reproduction, and it remains therefore a matter of
interest still to collect new facts respecting it. In the course

COHN, ON NASSULA ELEGANS. 97

of the last summer I had an opportunity of ascertaining
the existence, besides some incompletely observed instances,
of a decided, though peculiarly modified case of embryo-
formation, in the interesting Infusorium described by
Ehrenberg as Nassula elegans.

I found this rare animalcule at the same time with
Ophryoglena atra and Bursaria truncatella, \ately investi-
gated by Lieberkiihn. In form it resembles Paramecium
Aurelia, though rather narrower, ard, like Paramecium, it is
surrounded with a lattice-marked cuticle, supporting the cilia
which are uniformly distributed over the surface. The in-
terior of the animal presents yellowish-brown and _ violet-
eoloured pigment-masses, which are sometimes few in num-
ber and isolated, and at others aggregated into masses, and so
numerous as to fill the entire body. At the posterior part
of the animal, near the anal orifice, is situated a large violet-
coloured substance, which appears to be rendered of a deeper
colour from the presence of imnumerable dark-blue granules.
And occasionally a similar substance may be observed at the
opposite end of the body. Various opmions have been en-
tertained with respect to the nature of these masses. Hhren-
berg refers them to a class of bodies, the knowledge of which
has suddenly thrown a clear light upon many hitherto
obscure and doubtful points; he sees in them, in fact, a
special system, destined for the secretion of a violet-coloured
juice, visibly subservient to digestion, and therefore of a
biliary character. He describes an aggregation of beautiful
violet-coloured vesicles on the back of the animal, from
which is prolonged a series of violet or clear and colourless
vesicles along the dorsal region towards the anus. The
mixture of the coloured secretion with the contents of the
gastric cells, takes place in the posterior third of the body ; and
both are expelled at the same time. I am not, myself, as yet
quite clear as to the nature of these pigment-masses; though
it seems to me scarcely to admit of doubt that they belong to
that class of colouring matters met with so extensively in
the microscopical Algz, and more especially in the Oscilla-
rine and Nostochinez, and named by Nageli phycochrom.

The characteristic property of this colouring matter re-
sides in the circumstance, that either in the course of the
vital processes, or during the decomposition of the tissues, it
undergoes various changes of hue, such as into bright-green,
indigo-blue, violet, purple-red, olive-green, and brownish-yel-
low. Among the Oscillatorie we meet with species exhibit-
ing all these modifications of the phycochrom. It is a pe-
cuharity also of this material, that in the living plant it

98 COHN, ON NASSULA ELEGANS.

exists apparently in a solid form (mixed with the protoplasm),
but that during the slow decomposition of the tissues it is
gradually dissolved in the water, to which it communicates
a blue colour. Whence it happens that the water in which
Oscillatorie decay assumes a violet or blue colour, and the
paper upon which specimens of these plants have been dried,
exhibits a deep-blue border. The same colourmg principle
occurs, beyond doubt, in all the Infusoria which are distin-
guished by their variegated colours, changing from blue to
bright green and yellow, as in the odontophorous genera
Nassula, Chilodon, Prorodon, and Chlamydodon. The only
doubt which can arise with respect to the occurrence of
phycochrom in these animals, is, whether it reaches their in-
terior simply as the result of the digestion and assimilation
of the Oscillatorize, which notoriously constitute the principal
aliment of these genera, and fragments of which may usually
be noticed in the cavity of the body, or whether, like the
chlorophyll-vesicles of Lowodes bursaria, Spirostomum, or
Vorticella viridis, &c., it is not formed, in part at least,
within the animal, as a peculiar pigment. At present, I re-
gard the former supposition as the more probable. However
this may be, the masses of phycochrom are, after a time, re-
moved, collecting themselves, in Nassula elegans, previous to
their ejection, into large masses close to the anal region;
constituting in fact the violet-coloured masses composed of
numerous blue globules, noticed above as being contaimed in
the posterior part of the animal. ‘That the blue globules are
only drops of fluid phycochrom, is evident from the circum-
stance that when a Nassula is allowed to liquefy, the globules
suddenly coalesce into a blue fiuid, which immediately after-
wards loses its colour. It is manifest that m this case the
water penetrates from without into the interior of the animal,
and that in this water the droplets of phycochrom are im-
mediately dissolved. The ejection of the globules of phy-
cochrom through the anus and their sudden decoloration in
the water has already been figured and described by Ehren-
berg. I can see no reason for assigning to these blue masses
any function of a special kind in the nutritive system. Nor
on the other hand do I agree with Stein in regarding them
as fragments of Oscillatorie, considering rather that they
represent fluid particles of phycochrom extracted from the
Oscillatorie which have been devoured, and are in process of
digestion. Their assemblage on the back of the animal does
not seem to me to be a constant occurrence.

Other poimts of interest in the organization of Nassula
elegans are: the reel-like, funnel-shaped dental apparatus

COHN, ON NASSULA ELEGANS. 99

long since accurately described by Ehrenberg, and in which
that observer counted twenty-six teeth; and the nucleus con-
tained in the interior of the body. This nucleus is of an
elliptical shape, is 1-40’” in length, and has a groove at
one end, in which is lodged a minute nucleolus. The entire
mass is surrounded by a closely fitting vesicle, and in struc-
ture corresponds very exactly with the nucleus formerly
described by me in Lowodes bursaria.

Three contractile vacuoles are described by Ehrenberg in
Nassula elegans, two of which are said to be situated near
the oral orifice, and the third upon the ‘central gland” or
nucleus. I have, myself, only noticed two corresponding to
the first and second thirds of the animal; the occurrence of a
rosette-form in these vacuoles, as stated by Stein, to take
place in Nassula ambigua, I have not perceived.

In the spring of the past year I met with several speci-
mens of Nassula elegans, in whose interior might be observed
a large central cavity of an elliptical form and sharply de-
fined from the rest of the contents of the body. At the
point where the cavity most nearly approached the external
wall, the body of the animal presented a flask-shaped depres-
sion, and an elongated fissure, bounded by parallel walls,
leading from within to without. In the interior of the cavity
I observed one or two large spherical bodies 0-001” in
diameter, but never more than two. These spherical bodies
slowly entered the fissure through which the cavity commu-
nicated with the outer world, and in this way escaped into the
water. Having thus escaped, the spherules appeared mo-
tionless and colourless, having a granular texture with a
central nucleus and an excentric contractile vacuole. It
is a remarkable circumstance, that in these spherical bo-
dies I observed no trace of the ciliary covering by which
the movements of the embryos of Lowodes bursaria are
effected; on the other hand, however, the short, radiating
capitate filaments figured by Stein and myself in Loxodes,
were visible. No doubt, therefore, can exist as to the mor-
phological correspondence of the Nassula-spherules with the
“swarm-offspring” of Loxvodes, notwithstanding the absence
in the former of any motion which might possibly be owing
to the circumstance of their having been prematurely born
into the cold. I have unfortunately neglected to ascertain
whether the spherules in Nassula have any relation to the
nucleus, as asserted by Stein in other cases. The formation
of the reproductive spherules might even be observed in
individuals which, having but just undergone division, had
not attained to half their normal size. It is to be remarked

100 COHN, ON NASSULA ELEGANS.

that Stein has also observed the development of endogenous
embryos in Chilodon cucullulus, a near ally of Nassula; in
this case, however, the embryos were developed in the
encysted animals, made their way through the cyst in escap-
ing, and moved with the aid of long cilia; resembling the
Cyclidium glaucoma of Ehrenberg.

At the thirty-second meeting of German naturalists at
Vienna, Stein presented a series of remarkable observations
on the Acineta-formation from the swarm-offspring of Lowodes
bursaria, Stylonychia mytilus, Urostyla grandis, and Bursaria
truncatella (“Tageblatt de Versamml.’ No.3, p. 53). With-
out any desire of forestalling Stem’s more exact exposition,
I cannot avoid remarking that the reproductive spherules of
Nassula elegans, in their tentacular processes, do, in fact,
present an Acineta-like character, and the more so that they
are also deficient in vibratile cilia.

In his interesting memoir on the process of Encysting in
the Infusoria, Cienkowsky (S. and K. ‘ Zeitsch.’ Band vi,
p- 3801) has given us the developmental history of a nearly
allied species of Nassula, which he had previously termed
N. viridis, Duj. He and Stem have both observed the
process of encysting in this species, and Cienkowsky states
that after some time the body of the encysted Infusorium
breaks up into numerous sharply defined cells, neck-like pro-
longations from which perforate the wall of the cyst; the
contents of each cell then divide into a great number of
monadiform corpuscles (microgonidia), which escape through
the neck-like prolongation, and disperse themselves into
water. Should these observations, which fully correspond
with those of Stem on Vorticella microstoma, (Stein,
“ Infusor.” tab. iv, fig. 53—56, p. 194), really indicate a
mode of reproduction in Nassula, that Infusorium would
appear, besides transverse scission, to possess two wholly
different kinds of reproductive bodies, whose further develop-
ment, however, it must be confessed, is quite unknown.

It is very remarkable how closely the microgonidia ob-
served by Cienkowsky and Stein in the cysts of Vorticella
and Nassula, together with their flask-shaped parent-cells,
resemble the parasitic Chytridia met with in the interior of
many plants. ‘These are microscopic, unicellular fungi
whose ‘‘swarm-spores” penetrate the wall of a Conferva-
Spirogyra-, or <Achlya-cell or of a Closterium, and after-
wards expand in the imterior of these plants imto spherical
vesicles, which subsequently throw out neck-like processes,
with whose aid they break through the organism in which
they are nourished, whilst the contents of the fungus are

COHN, ON NASSULA ELEGANS. 101

transformed into innumerable swarm-spores, which are
discharged through the neck-like process. The history of
the development of these parasites has been cleared up in
the course of last year, (1856), by the observations of A.
Braun, Pringsheim, Naegeli, Klos, and Cienkowsky. And
on this subject should be consulted the memoirs of Braun
on Chytridium in the ‘Reports and Memoirs of the Berlin
Academy’ for 1856, and of Cienkowsky on Rhizidium Conferve
glomerate contained in the ‘ Botanische Zeitung’ for 1857.

102

REVIEWS.

Zur kenntniss des generationswechsels und der Parthenogenesis
bei den Insecten. Von Rup. Levcxart. Mit 1 Tafel.

(From Moleschott’s ‘ Untersuchungen zur Naturlehre des Menschen und der
Thiere,’ 1858.)

Tue author commences with some general remarks on the
bibliography and history of the subject,* and proceeds to
describe the ovaries of the oviparous and viviparous Aphides.
His observations on these insects, though not carried so far,
agree very closely with those previously made by Professor
Huxley.

In the Coccide, Leuckart has examined species belong-
ing to the genera Coccus, Lecanium, and Aspidiotus. As
to the general form of the female generative organs in L.
hesperidum, he confirms the observations of Professor Leydig.
The type of egg-formation in this species much resembles
that found in Aphis, and the egg is truly agamic.

Prof. Leuckart differs in many respects from the observa-
tions made by Professor Leydig. He states that the germi-
nal vesicle, though easy to be overlooked, is really present ;
that the vitellogenous cells take no part in the formation of
the embryo; and that the ovarian product is a true egg,
which, however, when laid, contains an almost mature em-
bryo, which is very soon hatched. In C. adonidum the
embryo is less developed at the time when the egg is laid.

Prof. Leuckart concludes with some general remarks on
agamic reproduction, and proposes to restrict the term ‘ Par-
thenogenesis’ to those cases where the egg, which is capable of
spontaneous development, is also susceptible of impregnation.

It is impossible, without exceeding our limits, to do more
than glance at the interesting and valuable observations
contained in this paper, the excellence of which will be fully
appreciated by those who have made this branch of science
their peculiar study, and which will fully sustain the repu-
tation of its author.

* Tn referring to the Daphniz he uses the term ‘ agamic eggs,” as syno-
nymous with the so-called “ winter eggs.” Mr. Lubbock, however, has
shown that while the common sort of egg is in Daphnia certainly agamic,
the winter- or ephippial-eggs require impregnation.

LEUCKART, ON INSECTS. 103

As far as concerns the Hive Bee, Prof. Leuckart confirms ge-
nerally the extraordinary facts related by Professor v. Siebold.
He examined several queen-bees which only produced drone-
eggs, and found generally that they were either virgins, or that
the supply of semen was exhausted. One or two specimens,
however, still contained spermatozoa, but they were rolled
together in a compact mass, so that apparently the compres-
sion of the spermatheca did not eject any of them. Kiichen-
meister has endeavoured to show that the impregnation or
non-impregnation of any egg depends on the relative posi-
tion of the spermatheca and oviduct, at the time when the
egg is passing through the latter, and in fact that the semen
flows out of the spermatheca, as water out of a flask. In
this manner Kiichenmeister thinks that by the form of the
cell alone he can explain the impregnation or non-impreg-
nation of the egg. Thus when the queen inserts her abdo-
men into the narrow cell of a worker, the pressure of the
cell-walls alters the position of the spermatheca, some of the
semen escapes from it, and the egg is impregnated. In lay-
ing an egg in a drone-cell on the contrary, no pressure is
exerted on the abdomen of the bee, and consequently the
egg remains unimpregnated.

If this were so, however, the number of queen-bees which
only produce drones would be much larger than it is, since
there are many which could insert their abdomen into a
worker’s cell without undergoing any pressure. Moreover,
the spermatheca is so deeply seated, and so much protected
by the other organs, that very considerable pressure would
be required. Finally, the spermatheca is bound down in its
place by numerous trachez, so that it cannot alter its position
unless these are torn.

M. Kuchenmeister was led to adopt this opinion from an
indisposition to admit that the queen-bee had the power of
determining the sex of her offspring, and of deciding whether
each egg should be impregnated or not. M. Leuckart,
however, seeks for an explanation of the facts in a reflex
action of the muscles, produced by the influence of external
circumstances, rather than from any exercise of the will.

He is inclined to attribute the fertility of certain working
bees to the nature of their food. In support of this theory
he mentions an experiment made by Dr. Dondoff, who fed
certain workers on eggs in honey. M. Leuckart dissected
eighteen of these bees, and found swollen ovaries in four of
them. None contained completely developed eggs, but this
was supposed to be from the short space of time during
which this food had been continued.

104 WILLIAMSON, ON FORAMINIFERA.

Fertile workers are far more numerous in the Ants,
Wasps, and Humble Bees; so much so that one can scarcely
examine a dozen specimens without finding several in this
condition. Indeed, in one nest of V. germanica, about half
the workers were fertile. They appear also to be more
numerous in autumn than in summer,

As in the bee, so also in the ants, the ovary of the fertile
workers has much fewer egg-tubes than that of the queen ;
in the humble bees, on the contrary, there 1s no such dif-
ference. The author, however, never met with a worker wasp
or humble bee which had been impregnated.

Huber long ago observed that in the Humble Bees the
eges laid by workers always produced males. M. Leuckart
has convinced himself that the eggs of worker wasps are
fertile, and Gundelach (‘ Nachtrag zur Naturgesch. der Honig-
biene,’ § 2) has observed the same in the Hornet, but in
these two cases the sex of the offsprimg was undetermined.

In the small moths belonging to the genera Psyche and
Solenobia there seems no doubt that parthenogenesis fre-
quently occurs ; and, indeed, the male of Psyche helix is not
yet known. As, however, in the Aphides and Coccide, so
also in this group, many differences of habit occur in different
species; thus in 8S. ¢riqguetella parthenogenesis appears to
occur much less frequently than in S. lichenedla.

The generative organs of these little moths are formed on
the same type as those of other female Lepidoptera, and even
possess a spermatheca. Neither is there anything in the
mode of formation or structure, of the eggs to indicate their
agamic nature. Not only do they possess a germinal vesicle
and vitellogenous cells, but they are also provided with a
micropyle consisting of sixteen to eighteen radiating canals,
and are therefore probably capable of impregnation, lke the
pseud-ova of bees.

On the Recent Foraminifera of Great Britain. By Wiir1aM
Craurorp Wiutiamson, F.R.S. London: Ray Society.

Tue publication of Professor Williamson’s work is a
triumph for the microscope that we must not pass over
without notice. This beautiful volume, which has been pub-
lished by the Ray Society presents for the first time, to the
British naturalist a full account of the living Foraminifera

~

WILLIAMSON, ON FORAMINIFERA. 105

found on our coasts. It embraces a very accurate de-
scription of each species, with a delineation by Tuffen
West. The only complaint we could possibly make about
the book is that the Ray Society has chosen to publish it in
a quarto form, when it would have been so much more con-
venient as an octavo, or even duodecimo. In these days of
locomotion, when we pack our microscopes into the smallest
possible space, we also want our books small, if they are to
travel with us. It was all very well for our forefathers to
publish quartos and folios, for they had leisure to admire
the grandeur of their tomes; but we have the greatest
difficulty in keeping up with our day, and everything that
spares time must be accepted as a boon.

Mr. Williamson has given an interesting history of the
discovery of the Foraminifera. From this we learn that
Hooke, the father of microscopical science, was the first
to describe a species of this family. In his “ Micro-
graphia” there is figured apparently a Rotalia, which had
been found in some sea sand. This was in 1665. There
it remained in solitary grandeur, the only representative of
this extensive family, for upwards of a century. About this
time, Mr. Boys published his ‘ Testacea minuta rariora,”
in which he gave drawings of twenty-two supposed species.
it was not, however, till Montague published his “ Testacea
Britannica,” in 1803, that the Foraminifera began to receive
that attention which their varied forms and curious nature
claimed. Still the group remained chaotic and misunderstood,
until D’Orbigny, in 1826, attempted to reduce it to something
hke order; who, however, committed the great error of refer-
ring these simple creatures to the group of Cephalopodous
Mollusks. In 1835, Dujardin showed the absurdity of this
classification, and placed the Foraminifera in his order Rhizo-
poda. The labours of Professor Williamson himself and of Dr.
Carpenter, and particularly of Schultze, have more recently
added much to our knowledge of them. Their position is no
longer a matter of doubt, and they are placed by the zoologist
amongst the lowest groups of the animal series.

The Introduction contains much matter of interest that
we might present to our readers, but we must content our-
selves with one extract on the method of collecting the
Foraminifera :

“ Localities and Modes of Collection.—A pocket-lens of moderate power
usually enables us to discover Foraminifera in shel/y sand from any part of
our coasts, but these are usually worn and imperfect specimens. The
common sand of our beaches is rarely productive in any degree. The home

of these objects is in the deeper parts of the ocean, commencing with the
Coralline zone of Forbes, where there is always a few fathoms of water,

106 WILLIAMSON, ON FORAMINIYFERA.

though a few occur in the shallower Laminarian zone, especially towards
its outer border. In the latter instance they are to be found amongst the
interlacing roots of the Laminariz, and especially amongst the tufts of
corallines with which those roots are so frequently surrounded. How far
their habitat extends into deeper water we have as yet no means of deter-
mining, since it is difficult to say whether the shells brought up from such vast
depths in the middle of the Atlantic* were living or dead at the time they
were collected. The same remark applies to the majority of the specimens
that have been forwarded to me by my dredging friends. I have found such
numerous examples of corallines with the sessile Foraminifera abounding
upon them as clearly prove that they both lived on the same ground. The
Foraminifera do not appear to affect districts where the ocean bed consists
of gravel or coarse clean sand, but preter localities where there is much
fine-grained oozy sediment. ‘This especially applies to the more delicate,
minuter varieties.

“The method of obtaining specimens must vary according to the object
in view; if the collector merely seeks dried shells for his cabinet, indifferent
whether living or dead, the process of floating them is by far the most
productive. A few pints of the sand must be collected from beneath, at
least, two or three fathoms depth of water, and thoroughly dried ; it should
then be passed through a coarse conchologist’s-sieve, or tlirough a piece of
coarse net, so as to eliminate all the rough material. ‘The finer portions
passed through the sieve must be poured into a bowl containing cold
water, and well stirred up, so that the whole may become saturated. On
being allowed to stand a few moments the more delicate of the concame-
rated shells, rendered buoyant by the air contained within their chambers,
readily float to the surface, whilst the sand and mud settle to the bottom.t
A little manipulation enables the collector to blow off this scum, so rich in
treasures, into an empty vessel, and the addition of fresh water further
cleanses the objects from impurity ; the creaming of the bowl being repeated
so long as any sediment or impurity remains. ‘The water may now be
drawn off by means of a syphon, and the objects dried, when they are
easily collected for examination. J have found it desirable to carry the
process a stage further before drying the shells, in order to obtain the
cleanest specimens: sweeping them off the moist sides of the bowl by means
of the forefiuger, I transfer them to a small evaporating dish containing a
solution of caustic potass,t in which I allow them to boil over a spirit-lamp
for some moments, thus dissolving the organic matter and leaving the cal-
careous shells free from impurity. The moment the lamp is removed the
shells settle to the bottom of the vessel, since the fluid has filled all the
chambers of each shell, displacing the air. The solution must now be
poured off, and the shelly residue be well washed in clean water; otherwise
drying will leave an efflorescence of alkaline matter on the specimens, mar-
ring their beauty. After washing they may be dried, when they are ready
for examination. :

“The advantage of the process here recommended lies in the facility with
which very unproductive sands are made to yield their tribute of specimens.
I have often obtained but a few hundreds of shells from several pints of
sand. It is obvious that the examination of such large quantities of ma-

* See Dr. Bailey’s Memoir in the ‘Smithsonian Contributions,’ vol. ii,
1851.

+ Care must be taken at this stage to break up the air-bubbles floating
on the surface, since these buoy up numerous inorganic particles which
require to be precipitated.

t The Lig. Potasse, P.L., is a convenient form for this purpose.

CLARKE, ON OBJECTS FOR THE MICROSCOPE. 107

terial under the microscope would involve a labour which the results would
not repay; but the above operation effects the purpose in a few minutes.
At the same time it is only the smaller and more delicate objects that can
be thus collected. The larger and heavier ones sink to the bottom of the
water along with the refuse sediment: by placing the weé sand on a flat
plate or dish, and gently shaking it, the shells rise to its surface, where
they are readily discovered by means of a pocket-lens. The superfluous
water should first be drawn off, with as little disturbance as possible, and
the sand dried, otherwise the glistening moisture interferes with the search.

“When specimens are wanted in a living state an entirely different pro-
cess must be adopted. On parts of the coast where the sand is coarse and
gravelly there is nothing for it but dredging up the smaller corallines and
seaweeds, and picking out the specimens one by one; but where the sea-
bottom is muddy and fine-grained the process applied by Mr. Warrington
to the oyster-ooze of Feversham is the best. It is just the reverse of the
floating process just recommended, since the chambers of the shells are
occupied with animal sarcode ; consequently they cannot be rendered buoy-
ant. The mud is put into a vessel containing water and well stirred up.
The fine inorganic particles are floated off, whilst the shells, from their
greater density and larger size, sink to the bottom; a repetition of the
washings leaves them perfectly clean.” (Pp. xii, xii.)

We cannot close our notice of this book without recom-
mending the Ray Society and its publications to our readers.
This Society has been the means of giving to the public
some of the most important works on natural history that
have been published during the present century. Its
labours are only limited by its want of funds; and we hope
that, if it be only for the sake of encouraging the publication
of such valuable works as this, that our microscopic friends
will be induced to join its ranks. The present work is to be
followed by one from Dr. Carpenter, on the physiology and
general history and arrangement of the Foraminifera.

We may also add that Dr. Bowerbank is now engaged in
the preparation of a work on the British Sponges, to be
published by the same Society ; and that little will then be
left to complete the history of the British Protozoa.

A Descriptive Catalogue of the most instructive and beautiful
oljects for the Microscope. By L. Lane Cuarke. London:
Routledge.

Tue idea of this book is a good one; and, on the whole,
it is very well carried out. It is, as the title-page indicates,
a description of microscopic objects. It supposes the reader
possessed of a microscope, and that he has access to

108 CLARKE, ON OBJECTS FOR THE MICROSCOPE.

microscopic objects by purchase or preparation. These
objects are arranged in something like a systematic manner,
beginning with general “objects from the vegetable king-
dom.” Then follows “sections of wood” and “ infusorial
earths.” After these come objects from the animal king-
dom, in which the author commences with spiders, and goes
through groups of insects capable of affording interesting
matter for the microscope, and leaves off with the “ spicules
of sponges.” “Slides of crystallization” finish the work.
The remarks under these different heads might have been
shorter, with advantage. The author has rather a tendency
to write, which is a damaging propensity where conciseness
is of value. Nevertheless, we think it will be found a useful
book.

A very short chapter “On the Use of the Microscope,”
introduces this instrument to the reader, and as the author
has here fallen into an error we must correct it. He
recommends to the reader “the Society of Arts Micro-
scopes,”’ and says—

“They are.made by Mr. Baker, 244, High Holborn, and
only cost £3 3s., complete in a neat mahogany cabinet.
They are excellent working imstruments, and, for their
utility and cheapness combined, were awarded a prize medal
by the Society from which they derive their name” (page 2).

Now we think most people would gather from this that
Mr. Baker gained the prize of the Society of Arts for his
microscopes, and they will perhaps be astonished when we
tell them he did not do so. The microscope to which the
Society of Arts gave their prize medal was one manufactured
by Mr. Field, of Birmingham, to whom the public is in-
debted for this cheap and efficient instrument. We know
that Mr. Baker may reply that his microscopes are of the same
pattern as the one which obtained the Society of Arts’ prize,
but we hardly think that this justifies him and his friends
in speaking of any instrument he makes as the “ Society of
Arts Microscope,” much less in claiming for him the award
of a medal which was given to another microscope-maker.
We do not say this to depreciate Mr. Baker’s microscopes,
—for aught we know they may be better than Mr. Field’s,—
but we think that the public ought, in fairness, to know who
is really the inventor and original maker of the “ Society of
Arts Microscopes.”

109

On the Mode of Formation of Shells of Animals, of Bone, and
of several other Structures, by a process of Molecular
Coalescence, demonstrable in certain artificially formed
products. By Grorce Ratney, M.R.C.S. London:
John Churchill.

Most of our readers will recollect a paper read by Mr.
Rainey before the Microscopical Society, and which appeared
in the ‘ Transactions,’ on the subject of this work. In that
paper Mr. Rainey pointed out the remarkable fact that
many of the appearances presented by the hard structures of
animals, and which had been usually referred to cell-deve-
lopment, were really produced by the physical laws which
govern the aggregation of certain salts when exposed to the
action of vegetable and animal substances im a state of solu-
tion. The paper to which we allude succeeded one which
he had previously published in the ‘ British and Foreign
Medico-Chirurgical Review,’ and the present work consists
of the observations contamed in these two papers, with
much new matter, both physical and anatomical. We need
not repeat or discuss here Mr. Rainey’s views, but we give
an extract from his Preface :

* What in this treatise I consider to have entirely originated with myself,
are—First, a process by which carbonate of lime can be made to assume
a globular form, and the explanation of the nature of the process, ‘ mole-
cular coalescence,’ by which that form is produced. Secondly, the explana-
tion of the probable cause of erystallization, and the manner in which the
rectilinear form of crystals is effected. Thirdly, the discovery of a process
of ‘molecular disintegration’ of the globules of carbonate of lime by invert-
ing the mechanical conditions upon which their previous globular form had
depended. Fourthly, the recognition, in animal tissues, of forms of earthy
matter analogous to those produced artificially. And fifthly, the deduction
from the above fact, and considerations of the dependence of the rounded
forms of organized bodies on physical and not on vital agencies. Being
anxious to present the results of my experiments and observations to the
public in as demonstrable a form as possible, I have, for the convenience of
those who wish to repeat and to extend them, given in detail all my pro-
cesses and formule ; and in the Physiological Section of this work I have
indicated the animals and parts best fitted for displaying the facts here de-
scribed, with the best way of preparing them for microscopical examination.
And in conclusion I may add, that I shall be glad to show, to such as are
interested in the subject, those preparations in my possession which have
been frequently referred to in the body of this work.” (Pp. vi, vii.)

The importance and interest of this subject can hardly be
over-rated. Mr. Raimey’s conclusions are directly opposed
to the views of many of our most distinguished histologists,
and they demand further investigation. The subject is one

110 BEALE, ON THE MICROSCOPE.

with which the microscopic observer alone can deal, and we
shall be glad to find it exciting the attention of our contri-
butors.

The Microscope in its application to Clinical Medicine. By
Lionet Beate, M.B. Second edition. London: John
Churchill.

On the appearance of the first edition of this work (vol. i,
p. 267) we gave it our highest commendation; and the
fact of its having so soon reached a second edition shows
that our high estimation of its value was correct. Short,
however, as has been the time since the publication of the
first edition, it has been one of great advaneement in the
direction of microscopical research. Hasty generalizations
have been corrected, incorrect observations have been ex-
posed, increased facilities for investigation, by the improve-
ment of the microscope, have been introduced, new methods
of research have been employed, and a large addition has
been made to our knowledge of minute structure, during the
last four years. For many of these results we are not a little
indebted to Dr. Beale’s book, and to the unwearied industry
and singleness of purpose with which Dr. Beale has worked
with the microscope. When we see how much work Dr.
Beale has done the last four years, and recollect that during
that time he has performed the duties of Physician to King’s
College Hospital, and Professor of Physiology in the College,
we cannot but marvel at the extent of his labours, and hope
that he is not taxing his physical powers to an extent which
he or his friends may have occasion to lament.

This second edition has been everywhere improved and
brought up to the time. Many new observations of impor-
tance, and much matter entirely new are added. Many
new woodcuts are given. We must also offer our thanks
to Dr. Beale for another improvement, and that is, a
copious quotation of authorities. This is done not only in
the text, but at the end of every chapter there is a list of the
works to which either the author is indebted for his informa-
tion, or which the student may consult for a more complete
knowledge of the subject.

The whole work has been re-cast, the arrangement is new,
the type is larger, and the volume bigger than the last. We

JONES S AQUARIAN NATURALIST. 1EE

can only repeat what we said of the first edition, with greater
emphasis, that ‘ we should be glad to see a copy in the hands
of every medical student and every medical practitioner in
the kingdom.”

The Aquarian Naturalist ; a Manual for the Sea-side. By
Tuomas Rymer Jones. London: Van Voorst.

Havine been indebted to the politeness of the publisher
for a copy of this elegant drawing-room volume, we have
pleasure in directing the attention of those for whose benefit
it is intended to its numerous attractions, though unable to
perceive that the Author has made much use of the micro-
scope in any researches which can be regarded as novel
in it.

From anything contained in the volume we should be
taclined to suppose that the greater part of the more recent
results of microscopic research has remained unknown or
unnoticed by Professor R. Jones. We regret, also, to have
to remark a general absence of that due acknowledgment of
the source whence much of his matter and many of his
illustrations are drawn, which should always be made even
in a popular work. Sir J. G. Dalzell’s name, though occa-
sionally noticed, certainly does not occur so frequently as it
ought, nor, as it seems to us, have his figures been much
improved in their transference to Professor Jones’s pages,
effected, though it has been, by the usually very skilful hand
of Tuffen West.

It is “splitting straws” to cavil about the title of a pro-
fessedly popular work like the present; but we may, at least,
be allowed to remark, that even Professor Jones is paying his
“lady friends” a poor compliment, in supposing that they
will not be sufficiently alive to the fact, that the ‘ Aquarian
Naturalist’ does not contain what might at least be expected
in it, some instructions as to the proper way of treating the in-
habitants of a marine Aquarium ; and that his book, in fact,
contains merely a series of remarks upon certain creatures
selected apparently at random among the numerous tribes
which inhabit the ocean; some of which are more or less
fitted to become the pets of an Aquarium, whilst others
are wholly incapable of such domestication. But those

VOL. VII. L

112 ' PAUL’S TECHNICAL ANALYSIS.

who covet only an amusing book, prettily illustrated, on sea-
side animals, will find this volume to their taste. Professor
Jones is a charming writer, and few men have a greater gift
of conveying information in a clearer or more graceful
style.

Manual of Technical Analysis, a guide for the testing and
valuation of the various natural and artificial substances
employed in the Arts and Domestic Economy, founded upon
the ‘Handbuch’ of Dr. P. A. Bolley. By Brnsamin
Pavt, Ph.D. London: Bohn.

In the examination of the structure and composition of
the various natural substances used by man in the Arts and
Domestic Economy, it is frequently necessary to use more
than one instrument of investigation. Where chemical
analysis fails the microscope succeeds, and where the micro-
scope is valueless the chemical reagents will frequently esta-
blsh facts of the first importance. It not uncommonly
happens that these two means of investigation are necessary
to arrive at correct conclusions. Substances which cannot
be obtained in sufficient quantities to be analysed with the
naked eye may be chemically manipulated with the greatest
success under the microscope. It is on this ground that the
microscope and chemical experiment frequently meet, and
the investigator of nature and the man of business must
appeal to both.

This volume deals principally with the application of che-
mistry to the testing of natural substances, but in doubtful
cases the aid of the microscope is called in. Thus, in giving
directions for the examination of milk, starch, vegetable
and animal fibres, the results of microscopic research are
presented. It is not, however, from this side of the question
that the principal facts of the book are presented, but from
the chemical side ; and we call the attention of our readers to
it, as a volume full of information on facts which they will
find of great service in those researches with the microscope
which have an immediately practical end in view.

113

NOTES AND CORRESPONDENCE.

Description of a Trough for exhibiting the Circulation of the
Blood in a Fish’s Tail.—During the meeting of the British
Association in Leeds last September there was an exhibition
of microscopes and microscopic objects at one of the soirées, »
when | showed the circulation of the blood in the tail of a
small gold fish, using for that purpose a trough invented
and made by Mr. T. Walker, a surgeon of this town.

The trough appeared at the time to excite some attention
from its convenience and efficiency, and as I have since
received several applications on the subject, I am induced
to think that a description of it may be of service to some of
the readers of the Journal.

As a proof of its efficiency, I may mention, that only one
fish was used during the evening, and that, although it was
kept for more than three hours under observation, it sus-
tained no injury, and is still living. The trough consists
of a piece of plate glass (a B c p), about six inches long,
and two inches wide ; upon this three pieces of plate glass,
about half an inch wide (£ B, B Dp), and pH, are cemented

EE:

with marine glue. Three pieces of strong covering glass;
about a quarter of an inch wide ( F, FG), and eG 4H, are also
cemented on to the plate. A piece of moderately strong
covering glass (E, F, G, H,) is then cemented on to the top of
the thin slips, and a piece of plate glass (2 H) cemented to
the top of the thin glass( z r @ u), and abutting on the ends of
the slips E B, H D.

The whole then forms an bpen trough (ru B H D), termi-
nating in a cell (e FG H), which is closed everywhere except
where it communicates with the bottom of the trough at the
line £ H. eek os

The fish, wrapped in a little wet linen, is placed iif the

114 MEMORANDA.

trough, so that the tail les im the cell © Fr G H, a small
quantity of water is placed in the trough, and the fish kept
in its place by one or two elastic bands or strips of thin sheet
lead passing round the glass, and over the body of the fish.

The advantages of this arrangement are—

Ist. The fish cannot throw up his tail and splash the
object-glass with water.

2d. In consequence of the tail being kept flat in the
cell the view is very good, and there is little risk of the object
getting out of focus.

3d. If the tail is not pushed too far into the cell the
vessels at its root are not compressed, and the circulation
goes on very freely.

4th. The fish may be kept on the stage of the microscope
for two or three hours without injury.

Mr. Macaulay, a philosophical instrument-maker in Leeds,
has suggested, as an improvement, that the three sides E B,
BD, and pH, should be made of a single slip of plate glass
bent to the shape required.—W. R. Miner, Wakefield.

On a mode of Illumination for High Powers.— Making pretty
frequent use of a one-quarter-inch objective by artificial
illumination, I found it a point of some importance, to
be able to get rid of the glaring fog, which often occurs,
in a ready and expeditious manner. The ground-glass
screen for use with the lower powers seemed to me to
be the readiest cure for the evil complained of; but, as
usually mounted beneath the stage of the microscope, it
is inapplicable in the case of the higher powers, from its dimi-
nishing the light too much; and the only plan seemed to be to
place it immediately under the glass slip carrying the object.
I accordingly ground, with fine emery and water, the surface
of a polished slip of glass 8x1 inches, and placed it on the
stage of the imstrument, throwing a moderately strong
light up from the mirror in the usual way. I then tested
the arrangement with several mounted slides of objects cal-
culated to try its efficiency, and I am glad to say that it
succeeded perfectly. Besides the freedom from glare, and
the rendering of the light very pleasant to work by, the
thorough dispersion of the rays imparts a very valuable pro-
perty to this method of illumination, which is at once
apparent in the manner in which it shows objects of high
refractive power. The sheathing scales on hair and wool, for
instance, are brought out remarkably well; the discoid
Diatoms in guano, sponge-spiculz, starch-granules, spiral and
scalariform tissue, the cell-contents-in Algz, are also shown

MEMORANDA. 115

very well. The action of the roughened glass is similar to that
of the paraboloid, but not to the same degree. The screens
are prepared in a few minutes, by rubbing two glass slips
together with emery powder and water between them. It is
well to have two screens, one finely, and the other more
roughly ground, so as to vary the effect according to the
subject under examination. The instrument used is one
of Smith and Beck’s largest size; the objective by Ross.—
Joun Keares, Liverpool.

Notes on the Calcareous Corpuscles of Tricuspidaria.—By T.
Srencer Cossoip, M.D., F.L.S8., Lecturer on Botany, St.
Mary’s Hospital, London.

The clear manner in which Claparéde appears to have de-
monstrated a relation subsisting between the calcareous
corpuscles and the excretory system of vessels in the Trema-
toda, induces me to call attention to these bodies in the
Cestoda, and especially in Tricuspidaria nodulosa. It would
seem that Dr. Guido Wagener had long ago discerned this
connexion in the Flukes; but as he had not published his
views on that point, it is to the former observer that we are
mainly indebted for this interesting discovery.

In the Cestode Tricuspidaria—often synonymised Trieno-
phorus nodulosus—narrow vessels may be easily recognised,
passing off continuously from the membranous capsules
investing the sclerous corpuscles; these vascular prolonga-
tions, however, instead of forming inosculations, as in Tre-
matodes, are single, and have their very limited course
directed outwards towards the clear structureless epidermis.
It is highly probable that they open at the surface, but I
have never been able to detect the slightest indication of
such an aperture.

Portion from the margin of the head of Pricuspidaria nodulosa. The vas-
cular prolongations connected with those corpuscles which are not in focus
are either only partially seen or cannot be observed at all. This specimen
was removed with others from theintestine of a Pike. Drawn with the
aid of a camera; X 300 diameters.

Dr. Wagener figures a structure precisely analogous to this
in plate xxix, attached to his Haarlem Prize Essay, the

116 MEMORANDA.

interest of the phenomenon being enhanced by the cireum-
stance of its occurring in the tail of a larval Trematode—
Cercaria macrocerca of Filippi. I do not find any explana-
tion of this structure in the essay itself, nor in Wagener’s
more recent ‘ Helminthologische Bemerkungen,’ published
in the same number of Siebold and Kolliker’s ‘ Zeitschrift,’ as
that in which Claparéde’s memoir is contained.* In Professor
Van Beneden’s ‘ Vers Cestoides’ mention is made of these
tubular extensions, in the detailed and accurate description of
this Cestode there given; and I have not yet received (De-
cember Ist) his great Prize volume—only a few copies having
at present crossed the Channel.

Although I have elsewhere expressed my adhesion to the
views of Siebold and others as to the dermo-skelctal cha-
racter of the calcareous bodies, I suppose we must—if Clapa-
réde’s observations are correct—henceforth regard these flask-
shaped capsules, with their contained sclerous particles, as
excretory organs, notwithstanding that they do not appear to
have any connexion with the water-vascular system.

Note on a Structure observed in Surirella—In the course of a
recent examination of some slides of Californian guano, the
material of which was communicated to me by Mr. J. T.
Norman, I observed an example of a species of Surirella,
exhibiting an appearance of considerable interest. The
frustule (which presents the side view) is injured, a consider-
able portion of the valve nearest to the eye being removed ;
the result is the exposure of a structure which, so far as I

Length -0040”. Breadth :0019”.
001”. Strie of median line 25 in 001”.

know, has not hitherto been noticed. This structure is a
strong, areolated septum or valve of a yellowish colour,
stretching across the entire frustule, distinct from, and

* See Translation, in another part of the present number of this
Journal,

MEMORANDA. 117

separating the two external valves. The areole are by no
means very minute, being only about 15 in -001", and they
are regularly hexagonal. The portion of the valve which
remains entire exhibits part of a narrow transversely striated
median line; and, arising from it, canaliculi, as in S. lata
and fastuosa, very couspicuous at the base, but suddenly
becoming inflated and faint. These characters are strictly
confined to the valve; for on accurately focussing the interior
organ, nothing whatever is perceptible but the beautiful and
uniform areolation. On slightly changing the focus, the
median line and canaliculi of the valve beneath are then
shadowed through. What is this interior organ? It does
not appear to have any intimate connexion with the valves,
for if that were the case, some trace of so marked a structure
would be visible by means of a strong transmitted lght.
Like the valves, it is highly siliceous. At first sight, this
remarkable arrangement would appear to be irreconcileable
with the views at present entertained relative to the character
of the Diatomaceous cell, and the process of self-division.
I must content myself at the present moment in merely
recording the fact, and in drawing the attention of students
of the Diatomacee towards it.

The larger figure is x 400. The smaller one, more highly
magnified, represents the areolated structure. — R.
Grevit_z, Edinburgh, Noy. 24th.

Microscopic Hints from Australia.— I have only lately re-
ceived the number of this Journal (No. XVI, p. 299), in
which appears an extract from a paper read by me before the
Victoria Institute, on some microscopic contrivances ; and the
new edition of Mr. Hogg’s excellent work, in which some of
my processes are noticed; and beg now to supply two or
three memoranda necessary to make them more intelligible.
In the description of my steam-bath, the word “ earth” ap-
pears instead of “ cork,” and is rendered by Mr. Hogg “ clay
or luting.” The escape-pipe for the steam is simply fitted in
a wide cork, which is more cleanly and convenient than
luting would be. I seem to have omitted mention of the
uses of this bath. It is designed to soften objects which have
been long kept in a dry state, or which are naturally too hard
to be readily mounted; also to prepare woods for cutting
sections, and to flatten the sections themselves when they
have curled in drying. The word “ eventually,” in the men-
tion of cyanide of potassium as a killing agent, should be
“eminently ;” but this is a trivial error, as the sense is eyi-
dent. I have, since that paper was written, used the cyanide

118 MEMORANDA.

of potassium with success. My plan is to expose the animals
to the vapour. I take a wide-mouthed glass jar, or a close
box with a glass lid, and introduce a false bottom of perfo-
rated card; below this I place a fragment of the cyanide,
which soon fills the chamber with its vapour. The jar or box
being kept closed, is always ready for the imtroduction of
insects, which immediately yield to its influence. Even the
Tarantula, which is remarkably tenacious of life, dies in a
few minutes. The animal is thus protected from the injury
which would be caused by contact with the deliquescent and
corrosive salt.

The animalcule-nets are round instead of pointed as figured,
they are thus both handier and more easily made.—W. 8.
Gipsons, Melbourne, Australia.

Microscopic Society of Victoria—The Melbourne papers
notice the formation of a Microscopie Society on the propo-
sition of Mr. W. 8. Gibbons, the honorary secretary. Of
course, in a new country, where all are absorbed in money-
getting, or, in the present critical times, in money-keeping,
there is considerable difficulty in getting people to work to-
gether in scientific pursuits. The number of members is
therefore small, and the desired limitation of membership to
workers can hardly be strictly adhered to. Microscopists
there are few, and need to supplement their forces by the
training of observers; this is being done. The Society
numbers about fifteen members, of which several are pro-
vided with good instruments, and are “doing.” Several
interesting objects, many of them new, have already been
forwarded to England. The Society meets monthly at the
residences of members. <A register is kept of colonial micro-
scopists, their instruments, libraries, collections, and pursuits.
The subscriptions are devoted to the importation of books
and appliances for the use of members. The honorary
secretary invites communications from all sources, and will
gladly reciprocate with observers elsewhere.

Communication from Frankfort-on-the-Main.—You will know
already from my letter I sent you some time ago, that in
Germany a mutual wish exists amongst microscopists, to
establish an interchange of preparations. For this purpose,
however, it is above all things desirable that one and the
same shape of making and getting up the preparations ought
to be agreed upon. In the enclosed paper you will find the
shape, as proposed by the Microscopical Society of Giessen,

MEMORANDA. 119

and the other as thought best by our Society. You will see
why we ascribe a great value to it, and why we desire that
our shape should be adopted. We consider it very desirable
that you should become well acquainted with the subject
concerning the interchange of preparations, as we hope it
might be possible that one day or the other we should see
realised our much felt wish—to establish in this way a close
communication between the microscopists of Great Britain
and Germany.

T am commissioned by our Society, to beg of you to insert
the paper in one of the next numbers of the ‘ Microscopical
Journal’—F, Funcx, M.D., Frankfort-on-the-Main.

“The Microscopical Society of Frankfort-on-the-Main is
fully aware of the paramount importance of establishing a
mutual interchange of microscopical preparations, as proposed
by the Microscopical Society of Giessen, and are very de-
sirous of participating in it. Every one interested in the
subject will feel much indebted for the great activity dis-
played by that society, and we do not doubt that the same
will lead to the best results for science.

“ Above all, we acknowledge how necessary it is for the
different societies to adopt the same form for the object-
glasses. Our society, however, is not of opinion that the
shape proposed at Giessen (37 to 28 millim), is a fortunate
one, as it does not answer general requirements; we, there-
fore, doubt whether it will be universally adopted, especially
in England, where, up to this moment, the greatest amount
of microscopical preparations exist. For this reason we have
deemed it advisable to employ every possible effort to intro-
duce a more useful shape, and we propose the object-glasses,
as introduced in our collection (55 to 25 millim, with pro-
tecting side glasses of 12 millim). At the same time,
however, we declare ourselves prepared to adopt any shape
proposed by the majority of microscopists. But, before the
interchange begins,is the most favourable moment to in-
stitute with the different societies inquiries upon this subject ;
this would be almost impossible when once any particular
shape has found an extensive general adoption. The reasons
against the shape proposed by the Giessen Society, as well as
an accurate description of ours, will be found in a. paper by
one of our members, Dr. Adolfus Schmidt, published in the
‘ Archiv fiir gemeinschaftliche Arbeiten, iii, 2. It may be
of some utility to annex a short extract from it, as, perhaps,
many a microscopist, especially botanists and zoologists, may
not have seen it.

120 MEMORANDA.

“1. The shape proposed by the Giessen Society is neither
convenient nor pleasing.

«2. The object-glasses are somewhat too large to be used
conveniently on the tables of the small microscopes of Ober-
hauser, Schiek, &c., most commonly in use (at least in
Germany).

«<3. The space for the label is too small.

«4. They require very small side-glasses, which are difficult
to be made in the thickness required by many preparations.

«5, The main objection to this shape is, that it requires
object-glasses of twofold size, one for marking purposes and
one for the preparations. Dr. Welker, who first introduced
and recommended this shape, mentions himself this deficiency
in his well-known pamphlet, ‘Ueber Aufbewahrung mikro-
scopischer Praeparate,’ &c., von Dr. Herrmann Welker,
Giessen, 1856, T. Riekersche Buchhandlung (page 7, note).”

“The shape, as proposed by us, does not, in our opinion,
possess any of these inconveniences; it is of the smallest
size possible for every use, is easily managed, and has suffi-
cient space for the label. The reasons alleged against the
use of long-shaped object-glasses (including ours), as men-
tioned in the paper published by the Giessen Society, are not
applicable to the shape proposed by us.

“1, They do not protrude over the margin of the tables in
any of the microscopes known by us.

“2. Neither our object-glasses, nor those of the Giessen
Society, can be turned round upon the small microscopes
in most common use; in this respect both have indeed the
same defect.

“3. The Giessen Society itself agrees that the labels used
by them are very{small ; at the same time, they say, that they
can be read while in the boxes. It is exactly the same with
our collection, as anybody may find in the description given
in the above-mentioned paper.

“4, The fourth objection fails of itself, as there are two
protecting borders in our object-glasses.

“5. With respect to the space left for the preparation
itself, ours is more than 100 5 millim larger than the Giessen
one, and it is a great advantage that it has one longer dia-
meter, in order to preserve longer preparations.

“‘ We, therefore, solicit every microscopist taking an interest
in the mutual imterchange, to decide for one of the above-
mentioned shapes, after having carefully examined every-
thing in their favour, or against them ; and we should deem it
advisable for him to give his opinion, when sending in his
first preparations. As for the present, we cannot deviate

MEMORANDA. L328

from the shape which we have found most to answer the
purpose.

“Dr. MreTTENHEIMER, President.

“ Dr. Getz, Secretary.

“ Frankfort-on-the-Main, 26th January, 1857.”

[We have inserted this communication at the request of
Dr. Funck, but we cannot but feel that it is too late to make
any alteration in the size or form of the slips used in England.
The Microscopical Society have decided that the size of three
inches by one is the simplest and most convenient. And as
already thousands of preparations exist m this form, and
thousands of slides are in daily use, both in England and in
France, it is to be hoped that German microscopists will see
the advantage of conforming to the same standard. Their
doing so would much facilitate the international exchange of
specimens, which is obviously so desirable.-—Eps. ]

122

PROCEEDINGS OF SOCIETIES.

Microscoricat Society, October 28th, 1858.
Dr. Lanxester, President, in the chair.

Eighteen presents of books were announced, and the thanks
of the Society returned to their respective donors.

Mr. Jackson presented eleven microscopical photographic
portraits, with the accompanying letter :

Sir,—Some of the learned and scientific societies of this
metropolis have ornamented the walls of their meeting rooms
with portraits of their distinguished members.

The Microscopical Society, having neither walls to orna-
ment nor funds to expend, cannot in this way follow the
example of their more opulent and longer established brethren;
and the next generation of members would seem to be pre-
cluded from the pleasure of contemplating the countenances
of the eminent persons who founded the Society, and watched
over its infancy.

Thanks, however, to the researches of one of our body, this
pleasure may still be secured to them; for, although we can-
not hang our rooms with portraits, these may be so reduced
as to occupy but a small space in our cabinet, and our micro-
scopes will always render them available for examination.

I therefore propose that one of our drawers be appropriated
to the reception of likenesses of our past and present mem-
bers; and as the art of taking these portraits, of a microscopic
size, is now practised by several persons, I do not despair of
seeing a respectable collection formed in a short time. As a
commencement I beg to present eleven of these photographs,
and I only regret that the number is so small. I have made
no invidious selection, not having omitted a single member
that has favoured me with a sitting; and if Mr. Shadbolt,
Mr. Hislop, Mr. White, and any other of our friends who
have taken up this branch of photography, will each do his
best, we may expect to see in our possession, within the next
twelve months, a larger number of authentic portraits than
most other societies can boast of.

PROCEEDINGS OF SOCIETIES. 123

In contemplating the progress and possible results of
microscopical investigation, one may be allowed to indulge in
a little speculation on the purpose which this collection may
serve.

While some microscopists are endeavouring to determine
the exact boundary between the animal and vegetable king-
doms, and are classifying with rigid accuracy the minute
organisms which border each side of that line, others, who
probably think with the poet, that

“The proper study of mankind is man,”

are carefully investigating the structure of the nervous system
in the higher animals. Should their researches ultimately
afford some insight into the operation of matter upon mind,
they may be disposed to carry them still farther, and, study-
ing the reflex action of mind upon matter, may reconstruct
the science of Lavater on a microscopic basis.

It is generally agreed that the physiognomy is modified by
the prevailing habits of thought. If this be true, there should
be found in every one of the portraits m our cabinet some
trait which would indicate a propensity to pry ito minute
matters, for that tendency may fairly be presumed to exist in
all of us. To discover this general trait will be the first object
of inquiry, and will probably occupy the attention of observers
for a long time before it is clearly determined.

Some of these members have contributed papers to our
‘Transactions,’ and have thus afforded particular indications
of their peculiar mental operations. The subjects they have
taken up, the manner of treating them, and even the style of
composition, show so many points of character, as to render
the study of these individual cases highly interesting to the
scientific investigator; and the circumstance that the minute
size of the pictures will oblige him to pursue it by the aid
of his favorite instrument, cannot fail to make it peculiarly
pleasing to the microscopist.

To pursue this speculation further would be a very unpro-
fitable occupation of your time, and I think I have already
said enough to give some idea of the immense field of research
which a single drawer of our cabinet may perchance afford,
when filled with objects which most of us will be inclined to
regard merely as amusing curiosities.—I am, &c.

GEORGE JACKSON.

A report from the Library Committee was read and ap-
proved.

124

PROCEEDINGS OF SOCIETIES.

A paper on “ Chlorosphera,” by A. Henfrey, Esq., was

read (Trans. p. 25.)

November 24th, 1858.

Dr. Lanxester, President, in the chair.

The followimg presents and purchases were announced,

and the thanks of the Society voted to
donors :

PRESENTATIONS.
Books.

Proceedings of the Academy of Natural Sciences of
Philadelphia

Journal of the Proceedings of the Linnean Society,
Vol. II, Nos. 8—10. : 3

Annuaire de Academie Royale .

Bulletins ditto ditto .

Notice of Remains of Extinct Vertebrata from the
Valley of the Niobrata River. By Joseph Leidy, M.D.

Report of Natural Sciences of Philadelphia, 14 :

Quarterly Journal of Geological Society, Nos. 55, 56

Proceedings of the Literary and Philosophical Society
of Liverpool, No. 12

Transactions of the Tyneside Naturalists’ Field Club,
Vol. III, Part4

The Canadian Journal of Industry, Science, and Art,
Nos. 15—17, New Series

The Microscope ; being a Popular Description of the
most Instructive and Beautiful Objects for Exhibi-
tion. By J. Lane Clarke

Notice of some Remarks by the late Mr. Hugh Miller,

Philadelphia :

Traité Pratique du Microscope et de son Employ
dans |’ Etude des Corps Organises. Par le Doctour
L. Mandl; suive de Recherches sur ]’Organisation
des Animaux Infusoires, par D. C. G. Ehrenberg .

An Account of some New Microscopical Discoveries,
founded on an Examination of the Calamay

Des Microscopes et de leur Usage—Manuel Complet
du Micrographie. Par Carles “Chevalier

Microscopic Objects, Animal, Vegetable, and Mineral ;
with Instructions for Viewing and Preparing them.
By A. Pritchard.

Micrographia_ Illustrata; _ or, the Microscope Ex-
nage By George Adams .

Dissertations relative to the Natural History of Ani-
mals and Vegetables. ‘Translated from the Italian
of the Abbé Spallanzani. 2 vols. ;

Nervous System of the ie oo Linn. By
George Newport :

their respective

Presented by
The Society.
Ditto.

The Editor.
The Society.
Ditto.
Ditto.
The Editors.

Ditto.

Jabez Hogg, Esq.

F.C.8. Roper, Esq.
Ditto.
Ditto.

Ditto.
Ditto.

Ditto.
The Author.

PROCEEDINGS OF SOCIETIES. 125

Presented by

Journal of Photographie Society, Nos. 66—73 . The Society.
Journal of the Society of Arts, 28 Nos. . The Editor.
Micrographia: containing Practical Essays on Reflect-

ing, Solar, Oxyhydrogen Gas, Microscopes, Micro-

meters, Eye-pieces, &e. : , - Geo. Jackson, Esq.
Schleiden’s Principles of Botany . Dr. Lankester.
Kiichenmeister’s Manual of Parasites, Vols. rs

Sydenham Society, 1856-57. Ditto.
Mémoires pour servir 4 |’Histoire @un genre de Poly-

Be d’eau douce & bras en forme de cores. Par

A. Trembley, de la Société Roiale ; . G. Busk, Esq.
Dr. Carpenter on the Microscope : . The Author.
Microscoric OxseEcts.

Two slides of Polycystina, from the bottom of the

Indian Ocean at 2200 fathoms . James Hilton, Esq.

Microscopic Portraits. Presented by Geo. Jackson, Esq.

Joseph Gratton, Esq. J. Shuter, Esq. J. Luke, Esq.

R. J. Farrants, "Esq. J. N. Furze, Esq. Rev. W. Quekett.

C. Varley, Esq. R. Warrington, Esq. G. E. Blenkins, Esq.

H. Peragal, Esq. G. Jackson, Esq.

PURCHASES.

A Monograph of the Cirripedia. Darwin. Ray Society, 1851. S8vo.
Bibliographia Zoologie. Agassiz. Vols. II], IV. Ray Society, 1852,
1854. 8vo.

A Monograph of the Cirripedia—Balanide. Darwin. Ray Society,
1853. 8vo.

Botanical and Physiological Memoirs. Ray Society, 1853. 8vo.

Alder and Hancock. ,Nudibranchiate Mollusca. Parts 6, 7. Ray
Society, 1855. 4to.

Microscopic Illustrations of Living Objects, with Researches concerning

the Methods of constructing Microscopes, and Instructions for using them.
dd edition. By Andrew Pritchard. Syo.

T. T. Gray, Esq., Bedford ; T. Thompson, Esq. Wakefield;
and P. Gray, Esq. St. Paul’s Villas, Camden Town, were
balloted for, and duly elected members of the Society.

Two papers, by W. 8. Gibbon, Esq., Melbourne, Australia,
were read—one on the Infusoria of the water of Tan Teen,
a large artificial reservoir in Australia, and the other on a new
method of Micrometry.

126 PROCEEDINGS OF SOCIETIES.

Britisu AssociaATION FOR THE ADVANCEMENT OF SCIENCE.
Leeds Meeting.
September 23d, 1858.
Section D.

On the Death of the Common Hive Bee, supposed to be
occasioned by a Parasitic Fungus. By the Rev. H. H.
Hieeins.*

On the 18th of March last a gentleman of Liverpool
communicated to me some circumstances respecting the
death of a hive of bees in his possession, which induced me
to request from him a full statement of particulars. He
gave me the following account: “In October last I had
three hives of bees, which I received into my house. The
doorway of each hive was closed, and the hive was placed
upon a piece of calico; the corners were brought over the
top, leaving a loop, by which the hive was suspended from
the ceiling. The hives were taken down about the 14th of
March ; two were healthy, but all the bees in the third were
dead. There was a gallon of bees. The two hives contain-
ing live bees were much smaller; but in each there were
dead ones. Under whatever circumstances you preserve
bees through the winter, dead ones are found at the bottom
of the hive in the spring. The room, an attic, was dry ;
and I had preserved the same hives in the same way during
the winter of 1856. In what I may call the dead hive
there was abundance of honey when it was opened ; and itis
clear that its inmates did not die from want. It is not a
frequent occurrence for bees so to die; but I have known
another instance. In that case the hive was left out in the
ordinary way, and probably cold was the cause of death. I
think it probable that my bees died about a month before the
14th of March, merely from the circumstance that some one
remarked about that time that there was no noise in the
hive. They might have died earlier, but there were certainly
live bees in the hive in January. I understand there was an
appearance of mould on some of the comb. There was, I .
think, ample ventilation, indeed, as the hives were suspended
they had more air than through the summer when placed on
a stand. When the occurrence was first made known to me
I suggested that the bees might probably have died from the
growth of a fungus, and requested some of the dead bees

* This paper was printed in the ‘ Proceedings of the Linnean Society,’
vol, ili, p. 29, August 20th, 1858.

PROCEEDINGS OF SOCIETIES. 127

might be sent to me for examination. They were trans-
mitted to me in avery dry state, and a careful imspection
with a lens afforded no indication of vegetable growth. I
then broke up a specimen and examined the portions with a
compound microscope, using a Nachet No. 4. The head and
thorax were clean, but on a portion of the sternum were
innumerable very minute linear slightly curved bodies,
which, when immersed in water, showed the well-known
oscillating or swarming motion. Notwithstanding the agree-
ment of these minute bodies with the characters of the
genus Bacterium of the Vibrionia, I regarded them as sper-
matia, having frequently seen others indistinguishable from
them under circumstances inconsistent with the presence of
conferve, as in the immature peridia and sporangia of
Fungi. In the specimen first examined were no other indi-
cations of the growth of any parasite ; but from the interior
of the abdomen of another bee I obtained an abundance of
well-defined globular bodies resembling the spores of a
fungus, ‘00012—00016 inch in diameter. Three out of four
specimens subsequently examined, contained within the
abdomen similar spores. No traces of mycelium were visi-
ble; the plants apparently had come to maturity and
withered, leaving only the spores. The chief question then
remaining to be solved was, as to the time when the spores
were developed, whether before or after the death of the
bees. In order, if possible, to determine this, I placed four
of the dead bees im circumstances fayorable for the ger-
mination of the spores, and in about ten days I submitted
them again to examination. They were covered with mould
consisting chiefly of a species of mucor, and one also of
Botrytis or Botryosporium. These fungi were clearly extra-
neous, covering indifferently all parts of the imsects, and
spreading on the wood on which they were lymg. On the
abdomen of all the specimens, and on the clypeus of one of
them grew a fungus, wholly unlike the surrounding mould.
It was white and very short, and apparently consisted wholly
of spores arranged in a moniliform manner like the filaments
of a Penicilium. These spores resembled those first found in
the abdomen of the bees, and did, I think, proceed from
them. The filaments were most numerous at the junction of
the segments of the abdomen. The spores did not resemble
the globules in Sporendonema musce. The Rey. M. T.
Berkeley, to whom I sent some of the bees, found, by
scraping the interior of the abdomen with a lancet, very
minute curved linear bodies, which he compared to vibrios.
He found mixed with them globular bodies, but no visible
VOL. II. M

128 PROCEEDINGS OF SOCIETIES.

stratum of mould. From the peculiar position of the
sphores within the abdomen of the bees, and from the
growth of a fungus from them unlike any of our common
forms of Mucedines, I think it probable that the death of

the bees was occasioned by the presence of a_ parasitic
fungus.

On the Liability of Shells to Injury from the Growth of «
Fungus. By the Rev. H. H. Hieerns.

Ir has often been observed that shells kept for a consider-
able time in cabinets are apt to lose much of their original
freshness and beauty of appearance. This kind of injury
chiefly affects such specimens as have a bright, enamelled
surface, which at length becomes dull and less pleasant to
the touch. Several suggestions have been made with refer-
ence to the probable cause of the change, which has often
been attributed to the efflorescence of saline matter absorbed
by the shell. But, so far as I have observed, the specimens
most lable to injury from saline incrustation belong to
genera im which the shells are without enamel, as Littorina,
Turritella, &c., and many collectors are in the habit of
steeping their specimens in fresh water for some days before
placing them in their cabinets—a process which is said to be
an effectual preservative from injury by saline efflorescence.
Mr. Denison, of Woolton, attributed the loss of lustre in
enamelled shells to the ravages of a minute insect, but had
not been able to detect the depredator. ‘ Many of the
shells in my own cabinet suffered such serious injury during
last winter that I was led to investigate the cause, which,
indeed, became obvious enough by the use of a microscope.
An ordinary lens showed the enamel of the shell to be beset
with small bristly pomts, and when a portion of the surface
was scraped off and submitted toa higher magnifying power,
the forms of at least two species of Fungi became ap-
parent, one resembling an ordinary Mucor with a globose
sporangium, the other and much more common form, exhi-
bited both simple and moniliform filaments, with an abun-
dance of minute spores, seemingly quite free. After having
been carefully washed, the surface of the shell was found to
be as if it were engraved in some places with stellular
marks, in others with striz forming irregular ‘reticulations,
caused no doubt in each instance by the spreading mycelium
of the fungus. It is scarcely necessary to add, that attacks
of this nature need not be apprehended where shells are
kept in a perfectly dry or well-ventilated place. A slight

PROCEEDINGS OF SOCIETIES. 129

deposition of moisture does, however, frequently occur upon
their surfaces whilst shells are undergoing examination, in
which case it would be a safe precaution to allow them for
awhile to remain exposed to the air before returning the
drawer to the cabinet.”

September 25th, 1858.

On the Anatomy of the Spinning Organs of the Araneide.
By Mr. R. H. Means:

Tue tegumentary covering of the abdomen in true spiders
consists of three layers, viz.: Ist, an external, horny, trans-
parent membrane, more or less densely clothed with hairs ;
2d, an intermediate soft stratum of pigmentary matter; and
3d, an expanded network of muscular fibres, which will
enable the spider to compress the contents of the cavity.
The spinnarets, seated near the apex of the abdomen, at the
under side, are mostly six in number, placed in three pairs—
an anterior, a posterior, and an intermediate pair. The pos-
terior pair is often prolonged and tri-articulate, when the
spinners composing it have been called anal palpi. There is
a fourth pair of spimnarets in Mr. Blackwall’s family of the
“ Cinifloride,”’ situate in front of the ordinary anterior pair.
They are short, compressed, and imarticulate. The spin-
narets are connected with the surrounding integument by
means of diverging bands of muscular fibres, which enable
them to move in various directions. In the interior of the
abdomen, nearer the base than the apex, there is a point
(opposite the orifice of the oviduct in the female), from
which several muscular bands radiate im various direc-
tions, keepmg the different abdominal organs in their
places. Some are inserted into the integument on both the
dorsal and ventral surfaces of the abdomen; others run
backwards in straight parallel bundles, and pass into the in-
terior of the spinnarets. These last bundles have their fibres
strongly striated, like the strong muscles connecting the legs
with the cephalo-thorax. The other muscles mentioned are
only faintly marked. The interstices between the organs
in the abdomen are filled with adipose matter, connected
into lobules by fine cellular tissue. This serves as a reservoir
of nutriment, and enables spiders to bear very long absti-
nence. The glandular organs, which secrete the silk, con-
sist of a number of sacsor bags and convoluted or branched
tubes, of various sizes and shapes—cach furnished with a dis-
tinct exeretory duct, which terminates separately on the sur-

1380 PROCEEDINGS OF SOCIETIES.

face of the spinnaret, so that there is no communication
between one and anether. The spmning glands may be di-
vided into four varieties. The first consists of a large
number of exceedingly minute cells, each containing a kind
of nucleus, and furnished with a very fine duct. These are
only found in the family of the Cinifloride, and are placed
immediately beneath the imtegument, near the supplemen-
tary spinnarets, with which they are connected. These
glands evidently secrete the fine silk, which forms the floc-
culus in the web of Ciniflo_(Clubiona) atrox and ferox. The
next group of spinning glands is the most numerous and
most constant of all the varieties. It consists of an immense
collection of small oval, or fusiform, cells, with fine elastic
ducts, which terminate principally in the anterior and pos-
terior pairs of spinners. These probably secrete the fine
threads, which weave the more delicate parts of the webs,
and construct the cocoons in which the eggs are deposited.
The third variety of silk glands contains several cartilaginous
sacs, or convoluted tubes, of a firm or even hard consistence,
but brittle and transparent. ‘These are often of a large size,
especially in the different species of Epeira. They have fine
inelastic ducts. Perhaps these secrete the adhesive lines
which are placed on the geometric webs of spiders. The last
and most interesting kind of glands are membranous sacs
and tubes, some vermiform, others clavate, others furnished
with branched cca. ‘They vary in size, some being very
large. All have thickened and apparently fibrous walls, and
they are all furnished with elastic ducts, having a fibrous ex-
ternal coat, composed of distinct rings, which break up into
separate pieces when the duct is stretched. From their con-
struction, these sacs and ducts must possess a strong contrac-
tile and expulsive power. They probably secrete the stronger
threads, which are stretched between distant points, and
form the framework of the webs; and they must also pro-
duce the gossamer of the aeronautic spiders, for they are
exceedingly large and numerous in Lycosa saccata and
Thomisus cristatus—common aérial species—which require
them for no other purpose, as they do not spin ordinary
webs, being erratic in their habits. In most other species of
Lycosa, also, the spinning organs are very slightly developed.
The ducts from both the cartilaginous and membranous
glands terminate in all the three ordinary pairs of spinnarets ;
several from the latter may be traced into the long triar-
ticulate spinnarets of Agelena labyrinthica.

PROCEEDINGS OF SOCIETIES. 131

September 27th, 1858.

On a new Species of Laomedea; with Remarks on the Genera
Campanularia and Laomedea. By the Rev. T. Hincxs, B.A.

A new British species of Laomedea was described under
the name of L. angulata, which is remarkable as being the only
member of this genus yet discovered in which the reproduc-
tive capsules are not axillary, but originate from the creep-
ing fibres. Mr. Hincks also described a remarkable variety
of Campanularia Johnstoni (Alder), which is branched, and
bears capsules on the pedicel as well as on the fibre. In
these two forms, the supposed distinctive characters of
Laomedea avd Campanularia are intermingled. There was
not, indeed, a single constant character that could be
relied upon for the separation of the two genera, and he
therefore proposed, with Van Beneden, to range both
branched and simple forms under Campanularia, abandoning
the genus Laomedea. One section, however, of Campanu-
Jaria seemed to him entitled to distinct generic rank, that
which includes the small and (for the most part) Sessile spe-
cles, and for this he proposed the name Calicella.

On some new and interesting Forms of British Zoophytes.
By the Rev. T. Hincxs, B.A.

A new species of Plumudaria was characterised under the
name of P. similis, closely allied to the P. echinulata of
Peach. Two new species of Polyzoa were also described,
one as Avenella dilatata, the other, which exhibits a new
generic type, as Arachnidia hippothdoides, a delicate ctenos-
tomatous Polyzoon, curiously resembling in general appear-
ance the well-known Hippothoa. Mr. Hincks also drew
attention to the remarkable difference in the form of the male
and female capsule in Halecinum Beanti and H. halecinum.

The Rev. W. Hincxs read a paper from Mr. Alder of
Newcastle-on-Tyne, “‘On three New Species of Sertularian
Zoophytes.” The first, taken on the Durham coast, was
Campanularia halecioides ; the second, taken off the North-
umberland coast, Halecium labrosum; the third, a foreign.
species, Halecium nanum, found amongst the Gulf weed.

Mr. Warrneton read a paper “On the Multiplication of
Actiniz in his Aquaria.” He described a process of repro-
duction occurring amongst these creatures, in which a portion
of the base becoming separated from the Actinia, split up
into three or four portions, each giving rise to anew Actinia.

132 PROCEEDINGS OF SOCIETIES.

Mr. Warineton described some additions which he had
made to his portable microscope, by which living objects
contained in glass bottles or small aquaria could be examined
with greater ease.

Mr. C. Brooks exhibited a microscope and case very com-
pletely fitted up, but having a stand of so simple and light a
character as to render it very portable and easily worked, even
in the open air, at the seaside or elsewhere.

Mr. Lapp exhibited a microscope with an improved mag-
netic stage. The improvements in the structure of the
microscope exhibited by these instruments were commented
on by several speakers. The facility of moving objects deli-
cately by the hand, afforded by the magnetic stage, was
remarked upon as a great advantage. Mr. Brooke’s imstru-
ment was fitted with a double lens, so that the power could
be changed from a high to a low one without unscrewing the
glass, and was regarded as an improvement that ought to be
more frequently employed in the construction of microscopes.

September 28th, 1858.
Section A.

On a New Law of Binocular Vision.
By the Rev. J. Drnexz.

Tue object of the law in question is to obviate the imper-
fect vision which would sometimes arise from the difference
of the pictures in the two eyes. In some cases this difference
would lead to great inconvenience and confusion. It some-
times happens, for instance, that m looking at a field of view
at some distance, objects considerably nearer are so interposed
as to present themselves in the picture formed in one eye and
not in the other. Thus, in looking at a landscape, if the
finger or any other object is held before one eye, the image
of it from the one retina is superposed in the sensoriwm on a
part of the landscape formed in the other eye. On mere
physical principles, this might be expected to blot out or
greatly confuse that part of the landscape upon which it was
placed; but upon trial this is not found to be the case, as
that part is merely a little dimmer than the rest from being
seen only with one eye, but is equally distinct and as truly
coloured. By various experiments the author had ascertained
that this was the result of a peculiar power of the will, by
means of which the mind is enabled, when two different
images are superposed in the sensorium, to select whichever
it pleases, to bring that object into view, and entirely to

PROCEEDINGS OF SOCIETIES. 133

obliterate the other; it sees, in fact, whichever it wills
to see, and the other image, simply by being neglected,
becomes invisible. In ordinary vision, the determination of
the image to be seen is effected by the same act of the will
which determines the position of the optic axes; but by
certain arrangements which were indicated both images may
be made to have the same relation to the optic axes; and as
the predisposition to select one or the other is thus obviated,
it is made indifferent to the mind which of the two images
that occupy the same place in the sensoriwm it shall see.
When these arrangements are made, it is found that mere
efforts of the will can easily bring either the one or the other
into view. The importance of the law, which enables the
mind to select its image, was pointed out in different cases of
ordinary vision. It obviates the difficulty already adverted
to, of haying two different pictures on the same spot; it has
not improbably an important influence in producing the
general stereoscopic effect ; it also, to some extent, remedies
the effect of squinting, by obliterating the picture in the
imperfect eye, which could not be else done without shutting
it. The effect of the law, in some extraordinary cases, was
also noticed, especially in the power of the will to fix images
on the sight, as Sir Isaac Newton instances in his own
ease (see his ‘ Life,’ by Sir David Brewster). The author
pointed out the great interest of the subject, not only in its
practical aspect, but also as having an important bearmg on
the connexion between mind and matter.

Dustin University ZooLtoGicaL AND BoTaNIcAL
ASSOCIATION.

April 16th, 1858.

Supplementary Catalogue of Desmidiacee found in the neigh-
bourhood of Dublin, with Description and Figures of a
proposed New Genus, ang of Four New Species. By
Wiiram Arcuer, M.R.D.S.

Class.—ALG i.
Order.—CHLoRosPORE or CoNFERVOIDER.
Family.—DesMmipiace2.
LEPTOCYSTINEMA, 0. g.

Plant an elongated jointed filament (often separating) ;

joints straight, much elongated and slender, without a

134 PROCEEDINGS OF SOCIETIES.

central constriction or inflation, entire, ends simply truncate,
or dilated and truncate (no evident gelatinous sheath).

1.—Leptocystinema Kinahani, n. sp.

Filaments attached, frequently breaking up into separate
joimts, which are slender, extremely elongate, linear, cylin-
drical, and smooth, their ends abruptly truncate; the junc-
tion of the halves marked by a pale transverse interruption
of the cell-contents; endochrome forming a compressed
longitudinal band, its broader diameter extending the entire
width of the jomt—the narrower not filling more than one
third, and presenting an undulating outline—-at the extrem-
ities of the joint more or less retracted from the end of the
primordial utricle, leaving a clear space, in which are active
granules; the endochrome also having immersed within it a
single longitudinal central series of light-coloured, well-
defined, globular, dense corpuscles, one of these bodies
occupying the centre of the transverse pale space.

Length of jomt varyimg from 33, to 34 of an inch
(averaging about ;4,5 in.); diameter of joint +7155 in.

It affords me much gratification to have it i my power to
connect the name of my friend Dr. Kinahan with this
species, while I feel it a privilege to be permitted to employ
this slight tribute of regard, and very unworthy recognition,
on my part, of many marks of consideration.

2.—Leptocystinema asperum = Docidium asperum. Bréb.

Filaments fragile ; jomts “ slender, cylindrical, rough with
minute scattered granules ;” “ends dilated ;” endochrome
disposed in an irregularly narrowed, somewhat undulatory, or
sub-spiral manner, sometimes bifid at the extremities, (or
“scattered” ?), and having immersed in it a single median
series of globular corpuscles, and usually with a pale space
at the centre.

Length of joint, 3, to & of an inch; breadth, z3;;;
breadth at end, 545. (These are the measurements given
by Ralfs, “ British Desmidie,” p. 159, with which my own
have agreed very closely.)

3. —Leptocystinema Portii, n. sp.

Filaments very fragile ; joints very slender, fusiform, very
gradually tapermg to the ends, where they become dilated,
giving to the apex a sub-capitate appearance, rough with
minute scattered granules ; endochrome disposed in an irre-
gularly contracted manner, having immersed in it a single

PROCEEDINGS OF SOCIETIES. 135

median series of globular corpuscles, and usually with a pale
space at the centre.

Length of joint varying from ;}5 to zs mch; diameter
at the middle of the joint, 3/55; just under the dilated
extremity, z,';5 ; and of the extremity itself, <3'55 m.

Although the compliment may be but an unpretending
one, it affords me great pleasure to have the opportunity of
associating the name of my friend, George Porte, Esq., with
this species—a gentleman whose manipulative skill in its
use is only equalled by his admiration of the many beautiful
objects brought to view by the microscope—while it will be
commemorative, too, of the origination and initiation by
him of a series of pleasant re-unions, at once scientific and
social, on the part of a limited little circle, in the number of
whom it is my own esteemed privilege to be counted a unit.

Another form to which I would next direct attention is
one in which I find a single, but important, difficulty, in
referring it to the genus Spherozosma, and it is the following :
I cannot find either one or two “glandular processes”
between the joints of the filament, the presence of which is
one of the characters of the genus Sphzrozosma (Corda).
The filament, which is very minute, is, however, plane and
fragile; while the joints, which are about as broad as long,
are constricted by a sharp, not deep notch at each side
between the projecting lateral inflations at the base of the
segments, giving a pinnatifid appearance to the margin of
the filament, which thus possesses all the characteristics of
Spheerozosma, save the one above noticed. Surrounding this
form I do not think there exists a gelatinous sheath; but I
am not able to affirm this at all confidently. The ends of
the segments are straight and abruptly truncate, each in
close apposition to the truncate end of the neighbouring
joint, without the apparent intervention of any “ glandular
processes.”, This form is very minute, and is very
fragile; hence seldom found having more than fifteen or
twenty joints in the filament, generally less; often one single
cell only is met with. The endochrome is light green, and
possesses a single “ vesicle’ (or corpuscle) at the centre of
each segment. Its minute size, the absence of the conspi-
cuous central solitary “ gland,” its truncate and square-
angled (not rounded) ends, and the lateral pouting projections
of each joint at the base of the segments, readily distinguish
this form from Spherozosma vertebratum. It differs from
Spherozosma excavatum, which it more nearly approaches in
size, by its square ends and lateral protuberant inflations,
with a sharp notch at the constriction at each side, and in

136 PROCEEDINGS OF SOCIETIES.

being wider at the basal inflation of the segments than at
the ends, not, as in Spherozosma excavatum, with rounded
ends wider there than at the centre, and having a deep, wide
sinus at both sides of the jomt. I may add that, so far as
my humble experience goes, the “junction-glands” of
Spherozosma excavatum are often very obscure. The sepa-
rated jomts of the form of which I have tried to convey
a conception, closely resemble a minute form of Cos-
marium, and such I thought a single joint was till I met it
in lengthened filaments. 'To obviate the difficulty here met
with, two courses may appear to be open: either to allow
this plant to remain as an aberrant member of the genus
Sphzrozosma—an unadvisable course if it could be avoided
—or else to alter the characters of the genus by omitting the
“junction-glands” as essential to it, for it appears, I think,
that the plane or compressed filament is itself enough to
distinguish Sphzrozosma from the cylindrical or angular
filamentous genera, except, perhaps, Aptogonum desmidium,
/, which, however, is distinguished by the foramina between
the joints. This view I would, then, very submissively put
forward. In any ease Ido not see I have an alternative but
to describe this form as a Spherozosma, as follows :—

Spherozosma pulchellum, n. sp.

Filament very minute and fragile; joints (including infla-
tions) about as broad as long; ends truncate, with square
angles; segments suddenly inflated at the base, and separated
from each other by a shallow acute notch, thus giving to the
margin, at each side, a pouting appearance at the central
constriction, each segment of the joints containing a single
central light-coloured fs SL)

Lea of joint, z5'55 n.; diameter of fea at the end,
assy 3 diameter at widest part of inflation, zasp IM.

I have also to bring to notice a species of Stawrastrum,
which, though minute, and not very striking in appear-
ance, there can be no doubt is undescribed. In the front
view this little organism might possibly be taken for a
small form of Arthrodesmus incus; but the central con-
striction is not so deep, nor is the constricted portion so
narrow, nor are the segments comparatively so dilated at the
ends, nor is the gibbous appearance at the base of the seg-
ments often seen in Arthrodesmus incus present in the form
in question; however, an end view, showing its four, or
frequently three angles, dispels all doubt, and at once pro-
claims the plant a Staurastrum. It differs from Stau-
rastrum dejectum (Bréb.) by its much smaller size and

PROCEEDINGS OF SOCIETIES. 137

less deep constriction, and angles not inflated in the end
view ; from Staurastrum cuspidatum (Bréb.), the end view of
which the triangular variety most approaches, by its much
smaller size, straight sides in end view, and non-inflated
angles, and by the want of a connecting band in the front
view. It resembles more nearly Staurastrum minus (Kiitz.),
an end view of which is figured in Ralfs’ Monograph, but
which has not yet (I believe) been found in Britain; but that
species presents five angles, not three or four, as in this
species. Ido not think I need contrast it with any other
species. The angles in the end view of the quadrangular form
are right angles, and the sides straight; in the triangular
form the end view is equilateral and straight-sided, both forms
possessing a single awn or acute spine at each angle. The
awns are a little longer in the triangular variety than those of
the quadrangular. I was fortunate enough to meet with the
Sporangium of this species; it is spherical and acutely
spinous; in fact, very like that of <Arthrodesmus incus.
That this form is a sort of connecting link, as it were, be-
tween Arthrodesmus and Staurastrum seems probable, from
the remote likeness in the front view to Arth. incus, as well
as from the similarity of the sporangium in each. I would,
therefore, venture to put forward the following to serve as a
description of this species :

Staurastrum O’ Meari, n. sp.

Frond very minute; segments smooth, ends truncate (in
the quadrangular variety slightly convex) ; central constric-
tion not deep, forming an obtuse angle; constricted portion
very short; a single awn at each angle; awns diverging in the
front view, acute.

End view quadrangular or triangular; sides straight ; angles
not inflated.

Sporangium orbicular, spinous; spines at first subulate,
afterwards slightly inflated at the base, acute.

Length of frond of quadrangular ata SEE6
br eadth at end (exclusive of Soe zso03
isthmus, 37'+5; length of spine, s¢'o0-

Length of frond of triangular variety, 755th of an inch;
breadth au end (exclusive of ey, aza07; diameter at
isthmus, 52455; length of spme, 3755:

Diameter of sporangium, vee including spines, 7759 of
an inch; including spines, 37th of an inch.

It is with very great pleasure I am permitted to call this
species after my friend, the Rey. Eugene O’ Meara, to whom I

of an inch;
diameter i

138 PROCEEDINGS OF SOCIETIES.

trust it may afford some gratification to have his name asso-
ciated with this species of a group kindred to his favorite
and beautiful Diatomacecze.

Penium Berginii, n. sp.

Frond minute, about three or four times longer than
broad, smooth, fusiform; segments cuneate; ends roundly
pointed; endochrome irregular, or sometimes with more or
less evident longitudinal fillets, also with a transverse pale
band, and having close to each end of the frond a con-
spicuous, well-defined circular cavity, containing moving
granules, and each half usually having immersed in the rest
of the endochrome a single central spherical corpuscle.

Length of frond, ,+, to 345 of an inch; greatest breadth,
sy Of an inch; diameter at the ends, ..¢, of an inch.

1 feel very happy in being accorded the privilege of naming
this species after the well-known microscopist, Thomas F.
Bergin, Esq., M.R.I.A, President of the late Microscopical
Society of Dublin; while I trust that gentleman may look
upon this trifling compliment as a mark of unaffected, but
sincere respect for his numerous scientific attamments, and
more especially in regard to microscopy, the active pursuit of
which has been interrupted owing to delicate health, at once
greatly to be lamented for his own sake, as well as much to
be regretted for the cause of science.

The following is the Supplementary Catalogue of Desmi-
diaceze found near Dublin (for preceding one vide ‘ Natural
History Review,’ ‘ Proceedings of Societies, vol. iv, p. 36) :”

Didymoprium Grevillit (A7v/z.), rather rare; though (like other filamentous
species) when met with, sometimes plentiful.
Leptocystinema Kinahani (mz), n. g., very rare.

[Hitherto met with but in a single pond on the Shank-

hill road, about a mile beyond Ballinascorney Bridge. |
asperum = Docidium asperum (Bréd.), not rare.
as Portil (mihi), not rare.
Spheerozosma vertebratum (Bréb.), rare.

i pulchellum (mhz), very rare.
Micrasterias Jenneri (2a/fs), rare.
Huastrum cuneatum (Jenner), rare.

ke insigne (//ass.), not uncommon.

Cosmarium Ralfsii (Bréb.), not uncommon.
3 tinctum (2a//s), rare.
Staurastrum O’Mearii (m7Az), rare.
brevispina (Bréb.), rare.
monticulosum (B7¢b.), rare.

[Of this rare and preity species, I have found a quadran-
gular variety (plate xi, tig. 16, exhibits an end view), as
well as the triangular form recorded in Ralfs. The former
differs from the latter only in possessing an additional side

”

2

27

PROCEEDINGS OF SOCIETIES. 139

and angle, and in the gatherings in which it occurred the
quadrangular variety was rather the more numerous; both
are rare, however. I do not think there can be any doubt
as to the form of which the end view is figured (fig. 16),
being the Staurastrum monticulosum (Bréb.), yet as the draw-
ing after M. de Brébisson in Ralfs appeared to me as not
quite characteristic, especially as to the end view, at least so
far as my plant was concerned, having the opportunity, I have
thought it might be worth while to introduce a sketch. The
diameter of end view is 1-700th of an inch; extreme length

of front view, 1-500th of an inch. |

AS gracile (Ralfs), rare.

4 tetracerum (K7/z.), rare.

- eyrtocerum (Bréb.), rare.

~s asperum (Bréb.), rare.

3 enorme (fa//s), very rare.

$s spongiosum (Bré6.), very rare.
rs aculeatum (Meneghinc), rare.
i spinosum (87ré6.), common.

oe vestitum (Ra/fs), rare.

Tetmemorus levis (Av¢z.), not rare.
Penium interruptum (Bréé.), rare.
» Berginii (mzhz), very rare.

{Sparingly, ina dyke above the Devil’s Glen, between the Water-
fall and the high road ; also in a pond on the “ Piperstown road,”
rather more than a mile beyond Ballinascorney chapel. |

Closterium Ehrenbergii (Mezegh.), not uncommon.

3 moniliferum (//7.), not uncommon.
a Jenneri (Ral/s), rare.

a intermedium (Aa/fs), rare.

A angustatum (A7zé¢z.), not uncommon.
" lineatum (Zhr.), not uncommon.

3 setaceum (Hhr.), not rare.

= acutum (Bréb.), not rare.

a juncidum 6 (Ralfs), rare,
Spirotenia obscura (Ra/fs), rare.
Pediastrum pertusum (A7z.), rare.
Scenedesmus acutus (Meyer), not rare.

ROYAL SOCIETY.
June 18th, 1857.

On the Early Stages of Inflammation.
By Josern Lister, Esq., F.R.C.S.

(Adbstract.)

In this communication the author gives an account of an
investigation with which he has been recently occupied, into
the process of inflammation in the Frog’s foot. The paper
is divided into four sections, with an introduction and con-
clusion.

140 PROCEEDINGS OF SOCIETIES.

The first section of the paper is devoted to the discussion
of the aggregation of the corpuscles of the blood. It is
shown by the author that the rouleaur “are simply the re-
sult of the disc-form of the corpuscles, together with a cer-
tain, though slight degree of adhesiveness, which retains
them pretty firmly attached together when in the position
most favorable for its operation, namely, when flat surface is
applied to flat surface, but otherwise allows them to slip very
readily upon one another.” The aggregating tendency of
the red discs is thus regarded as a phenomenon similar in
kind, though inferior in degree, to the well-known adhesive-
ness of the white corpuscles. It is further shown, from
numerous experiments, that the red corpuscles vary remark-
ably in adhesiveness, in consequence of changes in physical
circumstances, or very slight chemical action.

Section II is on the structure and functions of the blood-
vessels.

The thinness of the capillary wall is believed to favour the
mutual interchanges between the blood and the tissues, but
the consideration of some facts of physiology leads the author
to the conclusion, that notwithstanding the distending force
of the current of blood, the liquor sanguinis is not effused as
a whole among the tissues in a state of health; and this is
thought to imply that there subsists a mutual repulsion be-
tween the materials of the capillary wall and the elements of
the liquor sanguinis, preventing the passage of the latter into
the pores of the former, except in so far as they are attracted
by the tissues for the purposes of nutrition.

The heart is believed by the author to be the sole cause of
the circulation of the blood im the frog’s foot, and it is proved
experimentally that other sources of movement cannot have
more than a very trivial influence, and that their cessation,
supposing them to exist at all, does not give rise to arrest of
the blood or accumulation of corpuscles in the capillaries.

Distinct evidences of muscularity and contractility have
been detected in the veins of the frog’s foot, but compared
with the arteries, the veins show very little spontaneous con-
traction.

Regarding the influence of changes in arterial calibre upon
the blood in the capillaries, the author is led to conclude
that “the arteries regulate by their contractility the amount
of blood transmitted in a given time through the capillaries,
but neither full dilatation, extreme constriction, nor any in-
termediate state of the former is capable per se of inducing
accumulation of corpuscles in the latter.”

The influence of the nervous system upon the arteries has

PROCEEDINGS OF SOCIETIES. 141

formed the subject of a special experimental inquiry, the re-
sults of which are given in a supplement to the paper. It is
there shown that the contraction of the arteries of the frog’s
web are regulated by a part of the spinal cord, the irritation
of which induces complete constriction of the vessels, while
its destruction is followed by permanent dilatation. Neither
stimulation nor removal of the nervous centre for the arteries
produces any perceptible change in the quality of the blood,
as respects adhesiveness of its corpuscles or otherwise.

Section III. “On the Effects of Irritants upon the Circu-
lation in the Frog’s Web,” commences with an account of
some experiments performed with tepid water applied for a
brief period to the foot.

Subsequent experiments with a variety of other irritating
agents showed that the corpuscles, both red and white, were
obstructed in their progress through the irritated part m
consequence of their tending to adhere in an abnormal degree
to one another and to the walls of the vessels. The effects
upon the blood were always similar, although the means em-
ployed to produce irritation were exceedingly various, such
as solutions of salts, mustard, essential oils, chloroform, heat,
galvanic shock, mechanical violence, &c.

The well-known adhesiveness of the white corpuscles within
the vessels does not occur, according to the author, unless
some degree of irritation is present, and never exceeds that
which is always seen in blood outside the body. Hence the
inference is drawn, that the tissues of a healthy part exert an
influence on the blood in their vicinity, by means of which
the corpuscles, both red and white, are preserved free from
adhesiveness ; but that in an inflamed part this influence is
more or less in abeyance.

At the commencement of Section IV, “On the State of
the Tissues in Inflammation,” it is stated that “ the conclu-
sion arrived at in the latter part of the last section, that
blood flowing through an inflamed part, behaves itself in the
same way as when separated from the living body, naturally
leads us to infer that the tissues of the inflamed part are in
some degree approximated to the condition of dead matter, or;
in other words, have suffered a diminution of power to dis-
charge the offices peculiar to them as components of the
healthy animal frame. This inference is strongly supported
by considermg what common effect is likely to be produced
upon the tissues of the frog’s web by all the various agents
known to cause inflammatory disturbance of the circulation.”
It is then pointed out that all these agents, though differing
greatly in their nature, agree in their tendency to inflict a

142 PROCEEDINGS OF SOCIETIES.

lesion on the part to which they are applied, and impair the
functional activity of the tissues. ‘But strong as are the ar-
guments thus obtained by inference, it would be very de-
sirable to confirm them by direct observation of the tissues.
It fortunately happens that the pigmentary system of the
frog is a tissue which, from its peculiar form and colour, is
very apparent to the eye, so that it is easy to trace the re-
markably active functions with which it is endowed, and their
modifications under the influence of irritation.”

The author concludes: ‘‘Thus, direct observation of the
structures of the frog’s web which dischargefunctions apparent
to the eye, furnishes unequivocal support to the inference de-
rived from other considerations, that in inflammation the
tissues of the part, the primary seat of the affection, are in a
state of diminished functional activity.”

ZOOPHYTOLOGY.

In the ‘ Dublin Natural History Review,’ for July, 1858,
Professor Wyville Thomson has described several new genera
and species of Marine Polyzoa, collected for the most part by
Professor W. B. Harvey in the Australian seas, but with
which, with a view to the important subject of geographical
distribution, Professor W. Thomson has incorporated one or
two smaller collections sent to Professor Harvey with Algz
from various parts of the world.

Of this valuable contribution to Zoophytology we proceed
to give the following abstract, containing the description of
the new genera and species established by Professor Thom-
son; premising that the arrangement followed by him is
pretty nearly the same as that adopted by ourselves in the
British Museum Catalogue.

The new species are all figured, and of them we hope
shortly to be able also to give representations from original
drawings from specimens kindly furnished by Professor W.
Thomson.

Class —POLYZOA.

Order 1. P. INFUNDIBULATA.
Sub-order 1. CHxrILOSTOMATA.

Sect. 1. Articulata.
Subsect. 1. Uniserialaria.
1. Fam. CatENIcELLIDA, Busk.
1. Gen. Cutenicella, Blainville.

As usual in collections from the other side of the equator,
the Catenicelle are prominent and abundant. Most of the
species in the “ Rattlesnake” collection are repeated, and
seven undescribed forms occur. One new species belongs to
the fenestrate division ; the second differs so completely from
every described form as scarcely to be referable to any
of the formerly characterised groups, though occupying a
position to a certain extent intermediate between the two

VOL. VII. N

144, ZOOPHYTOLOGY.

first: four are vittate; and the seventh, though distinctly a
Catenicella, and closely allied to C. aurita (Busk), simulates
to a certain extent the structure of the remarkable genus
Calpidium.

in this genus, notwithstanding the numerous additions to
it, Mr. Busk’s original subdivisions retain their natural in-
tegrity. C. alata fraternises with the typical Fenestratze.
Busk’s specimen of C. aurita must have been poor. <A good
example differs so much from the Fenestrate group, and so
closely approaches C. geminata, which could not possibly be
associated with them, that it has been deemed advisable to
put the two species provisionally at the end of the list, thus
indicating the tendency of C. geminata towards the structure
of the next genus.

C. Harveyi stands alone a representative of the ‘ Fas-
ciate.” The position of the ovicell is very characteristic.

The new “ Vittate” are all normal. In this group there
are two modifications of the ovicell: in the greater number
it is galeriform and superior, encroaching on the cavity of the
cell above it, which is sessile, by a broad base on the ovicelli-
gerous one. ‘Two, C. ¢taurina and C. perforata, have a globu-
lar vesicle sessile on the older cell of a geminate pair.

a.—Catenicelie@ fenestrata, Busk.

. C. lorica, Busk.

. C. ventricosa, Busk.
. C. hastata, Busk.

. C. cribraria, Busk.
. C. alata, n. sp.

ore co tS

Cells pyriform. Fenestre 5—7.

Irregular grooves pass inwards from the fenestrae, giving the space within
a somewhat granular appearance. Lateral processes enormous, consisting
of a large hollow conical ascending process, with a pyriform opening in
front, a nearly tubular ‘“‘avicularian chamber” passing outwards opposite
the upper third of the cell-mouth, and ending in a minute avicularium; and
a wide hollow friuge continued down to the base of the cell, and iregularly
perforated in front. Ovicell (?).

The specimen figured is somewhat smaller and more
delicate than usual. The ccencecium does not appear to
attain a great size. All the specimens in the collection are
parasitical on other Polyzoa, and on red Algee. Old speci-
mens have often lost their large ascending processes, which
gives them a very different appearance.

Bass’s Strait; Dr. Harvey. Port Fairy; J. Dawson, Esq.

6. C. plagiostoma, Busk.
7. C.margaritacea, Busk. a

ZOOPHYTOLOGY. 145

B.—Catenicelle fasciate, Wyv. T.
8. C. Harvey, n. sp.

Ccencecium forming loose, handsome, curling, brown tufts. Cells large,
purely horny, vase-shaped ; expanded superiorly by moderately large lateral
processes, usually bearing large sublateral avicularia. External membrane
thin, loosely investing the inner, and raised into conical papille on the front
of the cell. Inner membrane strengthened by a raised strap of chitine,
continuous with the thickened rim of the cell-mouth, dividing immediately
below the lower lip, and forming a ring, again uniting and passing down the
middle of the front of its cell to its base; and by similar straps spreading,
apparently irregularly, over the avicularian processes, aud over the back of
the cell. Ovicell calyptriform; sessile by a broad base in the position of
one of the avicularian processes of a cell, which it replaces. Back of ovi-
cell furnished with a very large sessile avicularium.

Bass’s Strait; Dr. Harvey. A single tuft. This is a
remarkable and most distinct species. The cells are nearly
as large as, and resemble in form, those of C. amphora.

The cell-walls are very evidently formed of two mem-
branes, which remain distinct.

In dried specimens the inner and stronger coat retains its
form, while the outer appears to invest it in loose, wrinkled
folds, expanding into an irregular projecting frill round the
mouth. When the coencecium is boiled, to expel the air and
expand the tissues, the water passes freely between the two
layers, raising the outer wall into distinct papille, and show-
‘Ing it loosely hung round the cell.

The true avicularian chamber is a continuation of the
inner cell-wall, but the hollow lateral processes, whether
cups or spines, are formed of the thin outer membrane alone.

y.—Cuatenicelle vitiatea, Busk.

9. C. formosa, Busk.
10. C. elegans, Busk.
ll. C. Dawsoni, n. sp.

Cells rounded, gibbous ; lateral processes large, curved forwards and out-
wards, blunt, with usually a little depression, apparently an abortive
avicularium at the apex. Cell-mouth rather small, rounded; operculum
fe Surface of cell irregularly dotted with minute papillae. Vitte

road and short, sublateral near the base of the cell. Ovicell (?).

This species does not seem to attain a large size. There
appear to be two varieties, a broader and a narrower, but
agreeing in all essential characters.

The broad form occurs of a fine yellow-brown colour, and
in great beauty on Alge from the Freemantle district,
Western Australia (Harvey) ; and the narrower is abundant,
of a cinereous gray, on Bailia sent from Port Fairy by James

Dawson, Esq., of Kangatong, to whom I am indebted for

146 ZOOPHYTOLOGY.

many Australian rarities, and for much curious imforma-
tion.

12. C. castanea, nu. sp.

Cells ovate, elongated. Superior lateral processes small and rounded ;
united above the cell-aperture by a smooth prominent ridge; the lateral
processes continued round the lower angles of the mouth, so as almost to
form a corresponding ridge beneath.

Cell-mouth small and round. Operculum very thick. Avicularia small,
lateral; vitte linear, lateral, extending nearly the whole length of the cell.
Ovicell (?).

Coencecium forming graceful curling tufts. Cells of a rich
chestnut hue, contrasting well with the bright red of the
fibrous compound stem. Allied to C. gibbosa (Busk), which
does not occur in the collection.

Bass’s Strait ; Dr. Harvey.

13. C. umbonata, Busk.
14. C. crystallina, n. sp.

Cells subglobular, pyriform, fringed on either side by a wide hollow bor-
der, spreading upwards, outwards, and slightly forwards, into large lateral
processes, frequently furnished with small lateral avicularia, seated in cup-
like depressions.

Two arched markings, very constant in form, traverse this wide portion
of the lateral process, which is continued downwards in a hollow fringe to
the base of the cell.

Cell-aperture large; rim slightly prominent. Vittz long and well marked,
sublateral, and extending nearly to the level of the lower lip. Front of cell
studded with elevated papille, and whole surface ornamented with delicate
diverging lines, which give the ceencecium a beautiful glistening appearance.
An elevated ridge runs down the middle of the back, the lateral portions
falling off like the roof of a house, giving the transverse section of the cell
a somewhat triangular outline. Ovicell unknown.

Parasitical in delicate glassy tufts on Polyzoa.

Bass’s Strait ; Dr. Harvey.

A very distinct and beautiful form. The arches in the
hollow wings seem to be lines along whose course the mem-
branes of which the opposite walls of the wings are composed
are in contact. In the Vittatz generally the double cell-
wall is by no means so distinct as in the fenestrate group.
There are, however, frequent indications that the structure
is the same.

The vittee seem to be rows of bead-like spaces between the
layers.

15. C. Buskii, n. sp.

Cells almost cylindrical, slightly contracted towards the truncated base.
Connecting horny tube very short. Superior lateral avicularian processes
represented by longer or shorter slightly retrocedent spines, or by open
lacerated cups usually bearing small avicularia at the base. Spines longer

ZOOPHYTOLOGY. 147

in the newer cells towards the ends of the branches. Cell-mouth small
and round. Vitte linear, sublateral, extending nearly the whole length of
the cell. Front of cell slightly tubercular. Ovicell galeriform, superior ;
anterior surface slightly concave, bordered above by a projecting crescentic
beaded rim ; posterior surface convex, encroaching on the cavity of the next
oa against which it is cemented, and which is sessile on the ovicelligerous
cell.

Probably allied in habit to C. tawrina (Busk), as its resem-
blance to Thuiaria thuia is remarkable. Ccencecium very
calcareous.

Bass’s Strait; abundant; Dr. Harvey.

16. C. perforata, Busk.

Bass’s Strait; abundant; Dr. Harvey.

The ovicell of this pretty species resembles that of C. tau-
rina (Busk). It is galeate, tuberculate, sessile on the apex
of one of the cells of a germinate pair.

6.—Catenicelle simplices, Busk.
17. C. carinata, Busk.
New Zealand; Dr. Joliffe.

&.—Cutenicelle auritea, Wyv. T.
18. C. aurita, Busk.

Bass’s Strait and Fremantle; Dr. Harvey. Port Fairy;
J. Dawson, Esq. New Zealand; Dr. Joliffe.

Fine specimens have the front richly tuberculated. Three
or four tubercles below the mouth are perforate ; but there
is no approach to the true fenestrate character.

19. C. geminata, un. sp.

Axial cell geminate. The secondary cell developed alternately on either
side of the axis. Axial cells pyriform; a large gaping avicularium on the
angle opposite the secondary cell. Secondary cell giving off by a terminal
horny tube a single wedge-shaped peripheral cell. Cell-mouth large; a
deep notch in the centre of the lower lip. In the primary and secondary
axial cell four or five blunt spines surround the upper margin of the mouth,
which is surmounted in the peripheral cells by two longer ear-like processes.
Front of cell tuberculated. Ovicell unknown.

A small species, apparently generally distributed in the
Australian seas. Epiphytic on red Alge.

Bass’s Strait and Fremantle; Dr. Harvey. Port Fairy ;
Mr. Dawson. New Zealand; Mr. Joliffe.

Had it not been for its close resemblance to C. aurita
(Busk), evidently a true Catenicella, and with which it often
grows associated, one might have almost been inclined to
consider this curious little form the type of a new generic

148 ZOOPHYTOLOGY.

group, or an aberrant species of the genus Calpidium. As
in Calpidium, the cells have two “ key-holes;” but a sigle
glance must satisfy us that the cell consists of a primary and
a secondary chamber, bearmg the same relation to one
another that the two cells of a germinate cell bear at a bifur-
cation in any of the other species of the genus. C. geminata
bifurcates at every cell, so that all the axial cells are germi-
nate. The septum between the cells is traced on the back
of the cell by a deep groove in the usual position. The back
of the primary cell, both in this species and in C. aurita, is
frequently perforated to give origm to a horny, tubular
tendril. The secondary cell sometimes gives off a secondary
axis, but more usually only a single wedge-shaped cell,
apparently partially abortive. The ccenccium is very cal-
careous, and becomes very thick with age, a calcareous
deposit obliterating all the markings. The horny connecting
tubes between the cells are unusually long.

2.—CoTHURNICELLA, 0. g.

Cells in simple rows, each row arising from the side of a joint of an arti-
culated stem, each cell springing from the upper and back part of another
by a short horny tube. Cells all facing the same way.

Cell-mouth provided with a moveable operculum. Ovicell an ordinary
cell of a series, much enlarged, but scarcely modified in fori.

C. dedala, un. sp.

The only known species.

This genus seems to have a sufficient number of characters
in common with Catenicella to warrant its admission into
the same family. It is, however, at once distinguished from
the rest of the Catenicellide by its simple rows of cells
arising regularly from the joints of an articulated stem. The
joimts of this stem appear to be abortive cells. The last
joint of one branch is often dilated into a cell, while the
other branch ends in a single or double tendril of narrow
joints, and the final cell of a row is frequently capped by a
similar tendril, representing a continuation of the series. In
C. dedala the stem is at first simple, then makes a single
bifurcation, and the cells start in straight rows, a row from
the inner aspect of each joint of each branch, so that the
triangular space within the fork is closely strung, like a harp,
with parallel strings of cells. The anterior aspect of the
cellis narrow and slipper-shaped.

The mouth is placed near the top of the cell, large and
crescentic, with a thin projecting upper rim. A movable
semicircular operculum, with a raised edge, covers, or hangs
below, the cell-mouth. The operculum has at its base on

ZOOPHYTOLOGY. 149

either side a projecting triangular catch, which fits into a
notch in the lip. One would almost expect this apparatus
to shut with a snap like the clasp of a purse, it is so nicely
fitted, and so eminently mechanical-looking.

Below the cell-aperture a long, depressed area stretches
nearly to the base of the cell. The cell is much compressed
laterally ; the side view is much broader, and almost reni-
form. The cell-wall is double throughout, with a wide space
between the layers, thus forming two distinct chambers, the
inner not even resembling the outer in form. The anterior
depressed area is formed by the outer layer alone, so that
beneath there is still another space before reaching the inner
wall. In the centre of the area a tube passes through this
space, uniting two corresponding apertures, one in either
membrane, and thus communicating directly with the interior
of the cell. The side view shows the inner chamber as a
doubly bent expansion of the common tube of the ccnc-
cium.

Here and there one of the cells of a row is about double
the size of the rest. These large cells have their opercula
always closely shut. They are slightly more gibbous than
the others, but scarcely differ from them in form. They are,
doubtless, the ovicells.

The ccencecium is small and delicate, very calcareous, with
a beautiful pearly lustre. Parasitical on Fucoids.

Fremantle District, Western Australia (Dr. Harvey).

Subsect. 2 Bi-Multiserialaria.
2. Fam. SaricornariaAD, Busk.
1. Salicornaria, Cuv.
1. S. cenuirostris, Busk.

2. Nellia, Busk.
1. WV. oculata, Busk.

3. Onchopora, Busk.
1. O. hirsuta, Lamx. sp. ?

3. Fam. CrELLuLariap#, Busk.

1. Cellularia, Pallas.
1. C. cuspidata, Busk.

Abundant; Bass’s Strait; Dr. Harvey. New Zealand ;
Dr. Joliffe.

A very variable species. In one form the spine on the
median cell at the bifurcation is absent, and in another there
are two to three orifices in the back of the cell.

150 ZOOPHYTOLOGY.

2. Menipea, Lamx.

Cells oblong, abbreviated, or elongated and attenuated downwards ; im-
perforate behind with a sessile lateral avicularium (frequently absent), and
with one or two sessile avicularia (also frequently absent) on the front of
the cell. Ovicell globular, immersed in the internode.

This genus requires careful revision. It is said to be
distinguished from Emma (Gray) by the structure of the
cell-mouth, which is subtriangular in the latter genus, the
opening being partially filled up by a tubercular calcareous
plate ; and by the position of the lateral avicularium, which
in Emma is entirely below the cell-aperture; while in Me-
nipea it is seated, when present, on the upper and outer angle
of the cell.

The two new species are so completely intermediate that I
believe I am justified in unitnmg the Emme with the true
Menipez into what I conceive to be a most natural generic
group. MM. ternata (Ellis) may be taken as a type of the
genus thus constituted. MM. Fuegensis (Busk) approaches it
closely. The avicularia are still at the upper angle of the
cell, and the cell-lip is still simple. The operculum, however,
is reduced to a curved spine. In M. Buskii the lip is more
projecting, and the calcareous plate which partially covers
the cell-mouth is tuberculated. The lateral avicularium is
slightly depressed, though still opposite the upper third of
the aperture. The opercular spine is again expanded.

M. tricellota closely resembles the last in habit, but the
tuberculated plate round the mouth is still more fully deve-
loped, the lip is more elevated, and the much smaller lateral
avicularium is below the cell-mouth. The operculum is
again reduced to a rudimentary spine.

M. cyathus is binate, the cell-mouth large and simple, as
in M. ternata; the lateral avicularium very large half way
down the cell-mouth. The operculum once more expanded and
branched. It almost requires a microscope to distinguish M.
crystallina (Gray) from the last—they are so similar in habit
and general appearance; but in M. crystallina the expanded
operculum is again absent, the lateral avicularia are reduced
in size, and seated near the base of the cell, and the cell-
mouth is again contracted by a granular calcareous plate.

The right of this genus to the name of Menipea depends
upon the retention in it of the six-celled species, MW. cirrata
(Lamx.), of the propriety of which I think there can be
little doubt. The general character is still remarkably the
same. In M. cirrata a smooth plate covers the cell aperture,
the lower part calcareous and fixed, the upper portion a
movable, crescentic, horny operculum, closing over the true

ZOOPHYTOLOGY. 151

opening. I have not seen M. Patagonica (Busk), and from
the figure Iam more doubtful as to its position. All the
species are distinguished by the presence of one or more
sessile avicularia on the front of the cells, and by the re-
markable hollow curved spines attached round the upper lip
of the cell-mouth by horny joints.

This group does not seem to “fruit” freely. I do not
know the ovicell even in our common British species, M,
ternata (Ellis) ; but fortunately Dr. Harvey’s collection con-
tains a branch of M. Buskii from Bass’s Strait, bearing
several; globular, the surface granulated, immersed among
the cells in the middle of the internode. One can scarcely
doubt that all these closely allied forms have similar repro-
ductive organs, and, if so, the ovicells will give an excellent
generic character.

M. triseriata (Busk) and M. multiseriata (Busk), which
have their ovicells galeate and superior, like those of Scru-
pocellaria, must seek other congeners. é

I do not consider it necessary to subdivide the genus.

1. MW. cyathus, n. sp.

Cells very short and round; two in each internode, one a little above the
other; cell-mouth large, oyal, oblique; rim slightly thickened, five to six
spines round the upper and outer margin; the lower three, large, curved,
hollow, and pod-like, attached by a horny joint to the thickened lip.
Opercular spine expanded, branched, spreading downwards and outwards
from the upper and inner lip of the cell-mouth. A large sessile lateral
avicularium opposite the centre of the cell-aperture. Frequently an ante-
rior sessile avicularium between the two cells of the internode. Internodes
distant, a connecting horny tube extending from the apex of a pair of cells,
upwards and backwards, and slightly dilating as it enters the lower cell of
the succeeding pair by its anterior aspect.

There is constantly on the front of the upper of the two cells a ring-like
marking, usually filled up with a calcareous plate, but frequently giving off
a horny, tubular tendril. Ata bifurcation of the ccencecium a third cell is
introduced into the primary internode between the two secondary branches.
Ovicell unknown.

A delicate parasitical species, twining its long tendril-like
branches round zoophytes and red sea-weeds.
Bass’s Strait; Dr. Harvey. Port Fairy; Mr. Dawson.

2. M. crystallina, Gray.
3. M. Fuegensis, Busk.
4, M. Buskii, n. sp.

Cells elongated, attenuated downwards, three in each internode. Cell-
mouth large, oval, oblique, the lower third filled up by a tuberculated calca-
reous plate; upper lip prolonged, and fringed with from four to five spines,
attached to the lip by horny joints, and one of them, usually the second
from the outer edge, very long, curved, and pod-like. There is often an
additional spine on the upper and inner margin of the cell-mouth. Oper-

152 ZOOPHYTOLOGY.

culum spine strong and clavate, stretching upwards and outwards from the
lower and inner lip of the cell-aperture. Connecting horny tube between
the internodes double. Ovicell spherical, with a richly granular surface,
imbedded among the cells, on the cavities of two of which it encroaches.

Van Dieman’s Land; rather abundant, and in fine con-
dition: Dr. Harvey. New Zealand; abundant; Dr. Joliffe.

5. M. tricellata, Busk.

3. Serupocellaria, Van Beneden.

a,—Operculate.
1. §&. serupea, Busk.

Frequent on Algze and Polyzoa.
Bass’s Strait; Dr. Harvey. New Zealand; Dr. Joliffe.

2. 8. ornithorhyncus, n. sp.

Cell-mouth rather small, oblique, a tuberculated crescentic plate below
the lower lip. Upper margin fringed with four to five long spines; pedun-
culate operculum prolonged upwards into a spine, which, with the superior
spines, almost completes the circle round the true opening of the cell.
Lateral avicularia very large. Vibracula small and obscure. Ovicell
smooth.

A delicate transparent species, frequent, in small tufts, on
sea-weeds and Polyzoa.
Bass’s Strait; Dr. Harvey.
4. Canda, Lamouroux.
l. C. arachnoides, Lamx.

Sect. 2. Continua.
Subsect. 1. Uniserialaria.
4, Fam. Scrupartap#, Gray.

1. Scruparia, Oken.
1. §. chelata, L.

2. Hippothoa, Lamouroux.
l. H. Patagonica, Busk.

3. Altea, Lamouroux.
1. A. anguina, L.
2. A. ligulata, Busk.

Subsect. 2. Bi-Multiserialaria.
5. Fam. Fanrciminarrapm, Busk.

1. Farciminaria, Busk.
2. F. aculeata, Busk.

ZOOPHYTOLOGY. 158

6. Fam. GremeLnartap#, Busk.

1. Didymia, Busk.
1. D. simplex, Busk.

2. Dimetopia, Busk.
]. D. spicata, Busk.
2. D. cornuta, Busk.
3. Calwellia, n. g.

Cells in pairs, joined back to back. ach pair of cells arising by tubular
prolongations from the pair next but one below it. ach pair having a
direction at right angles to the next. At a bifurcation each cell of the
primary pair giving off a secondary pair. Ovicell subglobular, placed im-
mediately above and behind the posterior margin of the cell-aperture.

l. C. bicornis, n. sp.

The only known species.

This genus supplies another link in the beautiful chain of
modifications in the arrangement of cells in pairs furnished
by the Gemellariade. By combining one of the peculiar
characters of Notamia with a genera, appearance closely re-
sembling Dimetopia, it affords another reason for retaining
Notamia in the group, bearing, in fact, with the exception of
the total absence of avicularia, the same structural relation
to Notamia which Dimetopia bears to Gemellaria. The
lower half of each pair is contracted and tube-like, the two
lobes of which it is composed separating and curving over
the walls of the inflated triangular upper half of the pair im-
mediately beneath it. The coencecium is thus formed of
two incorporated, independent rows of pairs of cells, all the
cells of each row being in the same plane, but at right
angles to all the cells of the other row. This somewhat
complicated structure might be better understood, as the
author states, if the reader would imagine another exactly
similar double-stem incorporated at right angles with fig. 2a,
Plate IX of the original memoir.

The cell-mouth is small, nearly horizontal on the upper
surface of the cell. The margin is thickened, rising at the
outer angles of the nearly straight lower lip into a pair of
strong, incurved, blunt spines. The cell-wall seems to con-
sist of two membranes, and round the lower lip and at the
base of the spines there are a few small, oval and round,
fenestre, passing apparently through one layer only. <A
small, granular, perforated papilla rises immediately below
the cell-mouth, the oval aperture passing right through the
cell-wall.

The ovicell is immediately above and behind the m oh of
the cell, cemented against the triangular side of the pair of

154 ZOOPHYTOLOGY.

cells above, subspherical, slightly compressed, and beautifully
marked, as if stamped with a miniature clam-shell.

The coencecium is very calcareous, forming delicate pure
white, bushy tufts, about half an inch high.

It occurs sparingly with Cellularia cuspidata and Dime-
topia cornuta, parasitical on Catenicella ventricosa.

Bass’s Strait; Dr. Harvey. And on Catenicella hastata.
New Zealand ; Dr. Joliffe.

155

ORIGINAL COMMUNICATIONS.

Descriptions of Diatomacrex observed in CaLirorNiaNn Guano.
By R. K. Grevitxz, LL.D., F.R.S.E., &e.

Ir is well known that in studying Diatomacee as they
occur in guano and in deposits, the observer labours under
great disadvantages. The materials he has to work upon
are often scanty, and forms which attract his attention are
sometimes so scarce that he is obliged to review with the
utmost care a multitude of preparations before he can arrive
at a satisfactory conclusion regarding them. The conditions
so well laid down by Professor Smith, as requisite for the
determination of species, are in such cases, to a considerable
extent, beyond his reach. It has consequently been a ques-
tion whether any Diatom ought to be described except trom
recent, and, in some genera, actually lving individuals.
Undoubtedly it would be always desirable to conform to
such a rule when practicable ; but so many justifiable excep-
tions present themselves, that it can never be enforced as a
positive law. The best writers on this most interesting
order, even Professor Smith himself, occasionally deviate
from it. Witness his description of Himantidium (?) William-
sonit, made from specimens insufficient to determine even
the genus; for he had only the front view of the frustules
before him. Professor Gregory supplied the deficiency by
figuring the side view, and still the genus is not settled.
Nevertheless, it was unquestionably desirable that we
should possess good representations of so very curious a
production. Were we rigidly to confine ourselves to
those species only, whose history as living vegetables we
have the means of tracing, many of the most curious and
beautiful forms on record—even entire genera—would have
to be expunged from our books; such, for example as
Heliopelta, Asteromphalus, Asterolampra, &c. The truth
is, that while many frustules occurring in deposits require
to be described—if described at all—with extreme caution,
numerous others, especially of disciform genera, exhivit at
least sufficiently marked distinctive characters. All that
can be said, I apprehend, against the description of such
diatoms is that from the very nature of the case we are un-

VOL. VII. fe)

156 GREVILLE, ON.DIATOMACES.

acquainted with their history. Something, nevertheless, it
must be admitted, is gained by the publication of accurate
figures; for even if they fail in some cases to establish
species, they will at least assist to indicate the range of
variation, a point in itself of no small importance.

The prepared material of the Californian guano— the
richest in diatomaceous forms which has come under my
notice, and which has yielded, among many others, the
species described in this paper—was kindly supplied to me
by Mr. J. T. Norman, of Fountain Place, City Road,
London

Cocconets, KAr.

C. regalis, n. sp., Grev.—Frustule orbicular ; striz monili-
form, 5 in ‘001", occupying an elliptical space in diameter
about a third of the entire valve, the rest of the valve filled
with several rows of large granules concentric with both the
sides and extremities ; diameter 0030". (Pl. VII, fig. 1.)

In Californian guano.

The most splendid species perhaps of the beautiful genus
to which it belongs. The elliptical space occupied by the
few coarse striz stops considerably short of the margin of
the valve at each end, so as to admit of the rows of granules,
which diminish in size as they approach the extremities,
being continued round the whole valve. The granules are
very large and prominent, and have much the effect as if
they were the terminations of successive series of striz
curving up from below to the surface. Some of the granules
in the outer row are double and occasionally irregular.
This fine species seems to be most nearly allied to C.
Grevillii, a cosmopolitan Diatom, to which, in the structure
of the upper valve, it bears a considerable general re-
semblance.

Avtacopiscus, Hhr.

A. Oreganus (fig. 2), Harv. and Bail., ‘ Proceed. of Acad.
Nat. Se. of Philadelphia,’ vol. vi. p. 430.

At Puget’s Sound, Oregon, U.S., Exploring Expedition
under Captain Wilkes. In Californian guano.

Of this exquisite disc no figurehasbeen published. The single
example I have found in Californian guano agrees minutely
with specimens received from Professor Bailey in 1856, ex-
cept in the number of radiating lines and nodules. Professor
Bailey, in the specific character given in the work above
quoted, fixes the number at thirteen. But of the two specimens

GREVILLE, ON DIATOMACEZ. 157

which occur in the slide he sent me, one has nine nodules,
the other fifteen ; while the individual I have drawn contains
twelve, a striking instance how little dependence can be placed
on this character. Some species whose normal number of
nodules is four, occasionally show, as is well known, three or
five. Professor Bailey defines the structure in the present
Species as “ minute punctata;” but when magnified to the
scale adopted in the accompanying illustration, it is, although
minute, distinctly areolate to the eye. The diameter of the
‘valve is about ‘0045”".

Campytopiscwus, HAr.

C. stellaius, n. sp., Grev.—Valve orbicular; canaliculi
numerous, forming a narrow marginal band; strie radiating
in fasciculi from the centre, and interrupted about half-way
to the margin by an angular ridge and a row of very minute
puncta ; diameter ‘0044”; canaliculi 10 in ‘001”. (Fig. 3.)

In Californian guano.

Few genera exhibit more varied sculpture than Campylo-
discus ; as may be seen by glancing at the species figured in
the ‘ Synopsis of the British Diatomacez,’ at those described
by Professor Gregory in the 21st volume of the ‘ Transactions
of the Royal Society of Edinburgh,’ and at the two very
remarkable ones given by myself in Pl. III of the 5th volume
of this journal. The present species differs from them all in
the peculiar ornamentation of the centre of the valve. I
have called the centrical radiating lines strie, as they seem
to be of a different nature from the canaliculi which form
the external border; it must be admitted at the same time
that they appear to pass into the broad band intermediate
between them and the border. As the striz proceed from
the centre others originate at irregular intervals between
them; and at about half-way between the centre and the
circumference an interruption occurs in the shape of a rather
sharp ridge, on which is disposed an irregular row of very
minute puncta, which require careful focussing to bring out.
The more definite strive (canaliculi?) which compose the
intermediate broad band, are transversely undulated, giving
them a semi-moniliform character, in this respect resembling
the corresponding band in C. limbatus. Indeed, were the
central radiating strize absent, the frustule would approach
very near to that species.

AsTERoMPHALUs, Ehr.

‘The genus Asteromphalus was described by Ehrenberg in
‘Berlin Monatsberichte,’ 1844, p. 198, where he defines seven

158 GREVILLE, ON DIATOMACE. °

species, all collected in the Antarctic regions during the
voyage of H.M. Discovery ships Erebus and Terror, by Dr.
Joseph Hooker, the talented and imdefatigable naturalist of
the expedition. The specific differences are founded by
Ehrenberg, and subsequently by Kutzing (‘Sp. Alg., 1849),
on the number of “marginal rays” and on the straight or
crooked direction of the ‘‘ umbilical rays.” In 1856 another
species was described by the late Professor Bailey (‘ Amer.
Journ. of Science and Arts,’ vol. xxii, p. 1), and named
by him Brooket in compliment to Lieutenant Brooke of the
U.S. Navy, who obtained it from a depth of 1700 fathoms
in the Sea of Kamtschatka. Professor Bailey derives his
specific character from the ‘umbilical rays,” placing no
dependence whatever on number, either in the present genus or
in the “allied forms of Asterolampra, Heliopelta, Actinoptychus,
Actinocyclus, &e.”

If this view regarding number be correct, and it is now
being very generally adopted, the Antarctic species of
Asteromphalus will probably have to be reduced ; but in the
absence of authentic specimens it is impossible to speak with
any certainty. In his ‘ Mikrogeologie,’ tab. xxxv (xxi),
Ehrenberg has figured four out of his seven species, and it
is remarkable that in every instance the ‘“ umbilical rays”
are represented as all given off from the very extremity of
the ‘‘ base of the median line,” or, if De Brébisson’s view be
received, who does not recognise ‘umbilical rays,” the
enlarged bases of the rays meet at one point, however
numerous they may be, and are not planted along the sides
as well as on the apex of the base of the median ray, as is the
case in every species more recently discovered. It would be
interesting to know whether, in all the Antarctic species, the
apex of the base of the median ray is precisely centrical as
represented in the ‘ Mikrogeologie ;? and whether the “ um-
bilical rays’ invariably arise from that point.

Early in 1857 De Brébisson proposed his new genus
Spatangidum (‘ Bulletin de la Société Linnéene de Norman-
die,’ vol. 11), for the reception of certain forms nearly allied
to Asteromphalus, which he had observed in Peruvian guano.
His character is in the following terms:

“ SpatancipuM, Bréb.—Lorica simplex, bivalvis, suborbi-
cularis, valvula una convexiore. Discus cellulosus vel gran-
ulosus, uterque stelle excentrice radiantis notatus, radiis
(ambulacris) levibus.”

His great mark of distinction is the excentrical position of
the rays; but I fear that this character cannot in every case
be relied on. I have seen various discs where it was scarcely

GREVILLE, ON DIATOMACES. 159

possible to determine whether the rays were centrical or ex-
centrical. The outline also of the valve is subject to varia-
tion. When it is more or less ovate, the rays are excentrical ;
but when the valve (in the same species) becomes more
nearly orbicular, the rays then become more centrical. I
am now speaking more particularly of those species which
have a granulated structure and general diaphanous ap-
pearance. In Spatangidum Arachne and 8S. heptactis of
Brébisson, the rays are always more or less excentrical, and
seem to constitute a really permanent character, which,
taken in connexion with the more important difference of
structure, viz., the distinct areolation, will justify, I think,
the separation of these two species from Asteromphalus.

With regard to the parts of the valve on which specific
value may be placed in the two genera, we must be guided
by the results of extended observation. I am inclined to
believe that, closely as these genera are allied, the same parts
are not of equal value in both. In Spatangidum, as I pro-
pose to restrict that genus, the number of the rays in the
several species seem to be constant. The rays themselves
afford good characters, as well as the lines of the hyaline
area (umbilical rays of authors). In Asteromphalus, on the
other hand, the radiating lines of the hyaline area (including
their insertion on the nucleal line) seem alone to furnish
reliable distinctions. In studying the composition of these
beautiful discs, of both Asteromphalus and Spatangidum, I
have been led to take the view of Kiitzing, who considers these
radiating lines as ‘‘ sepimenta imperfecta.” They terminate
abruptly, precisely as in Asterolampra. The true rays may
be said to commence from the outer edge of the hyaline area,
for they are merely blank spaces in the areolation or granu-
lation of the disc. It is true that as the intervals between
the lines of the hyaline area are a sort of continuation of
these blank spaces, they may, in this point of view, be con-
sidered as the ‘“ enlarged bases” of the rays, and thus, ac-
cording to De Brébisson’s idea, be directly imposed on the
“base” of the median ray, or, as I prefer to call that part,
the nucleus or nucleal line. In A. Brookei, however, such
an arrangement can take place to a very partial extent, as
Professor Bailey describes the “ umbilical rays” as “ flexuose,
some simple, others branched, or two or more uniting before
reaching the centre.” These lines are also occasionally
forked in a species I have found in South African guano.
It seems to me, therefore, advisable to take such characters
as the lines of the hyaline area afford independently of the
rays.

160 GREVILLE, ON DIATOMACKEA.

In accordance with the views which I have expressed, I
now propose the following modification of the generic charae-
ter of Asteromphalus.

AstrrompPHaLus, Ehr.—Frustules simple, two-valved, disci-
form, finely granulated; each valve marked with acuminated ©
rays, proceeding from a centrical or excentrical hyaline area,
the median ray very narrow.

I would here place the species described by Ehrenberg and
Bailey, and also Spatangidum flabellatum and S. peliatum
of De Brébisson. ‘There is, in fact, no character what-
ever to separate the last two from this genus, except the
excentrical hyaline area, which, as I have already stated, is
sometimes an extremely ambiguous distinction. The Aste-
romphali are very hyaline and delicate, the rays acuminate,
and the structure minutely granulate. In natural hahit
they all agree. I have detected in Californian guano cer-
tainly two species; one new, the other possibly a variety of
A. flabellatus; but I speak on this point with considerable
hesitation. Indeed, I find it difficult to draw a satisfactory
line between A. flabellatus and A. peltatus. The former,
according to De Brébisson, has some of the rays subarcuate.
The specimen (fig. 4) appears to be identical, only the
rays are all straight. I have also represented, at fig. 5,
another more perplexing form. It will be perceived that it
is nearly quite orbicular, and that the hyaline area is very
nearly centrical, and, as in the last illustration, the rays are
all straight. I cannot, however, see how this can be sepa-
rated from A. flabellatus, because the previous variety seems
to form the connecting link. I may here mention, that I
have a beautiful frustule, origm unknown, ovate in outline,
with a very excentrical hyaline area, and eight rays, one of
them short, and opposite to the median ray, as in A. peltatus ;
the rest decidedly arcuate. If the number of rays be imma-
terial, this will also have to be referred to A. flabeliatus, as
well as another now before me with nine rays. In two spe-
cimens of a fine species obtained from South African guano,
the frustules of which are very nearly orbicular, and the
hyaline area not far from being centrical, there are ten rays, all
of which are straight; but the two lower lateral lines of the
hyaline area on each side are arched downwards (the median
line being directed towards the spectator). The granulation
of the disc is also larger. This is probably a distinct species.
I would not venture, im the absence of authentic examples,
to say anything further regarding A. peltatus. ‘The short
ray being in the same direction with the median ray and

GREVILLE, ON DIATOMACEZ. 161

nucleal line, contributes to give the “subpinnate” character
to the four pairs of lateral rays which De Brébisson has
noticed; but we must keep in mind that, if instead of the
short middle ray, two were introduced, as in figs. 4 and 5,
the subpinnate character would be lost.

A. elegans, n. sp., Grev.—Radiating lines of the hyaline
area with an angular bend in the middle, and inserted on the
end and sides of the nucleal line; diameter of disc -0030’.
(Fig. 6.)

In Californian guano.

I have only seen one example of this most beautiful spe-
cies. It is very nearly, though not quite perfectly orbicular,
and the hyaline area is almost centrical. The rays, thirteen
in number, are equidistant. As, however, all these features
are liable to variation, I have not introduced any of them
into the specific character.

Spatancipum, Bréb.

It is with no trifling degree of hesitation that I venture to
dissent, in some measure, from so eminent an authority as
De Brébisson ; and it will afford me much satisfaction if, on
a revision of the subject, he shall approve of the manner in
which I have modified his genus.

SpaTancipum, Bréb.—Frustules simple, two-valved, disci-
form, distinctly areolated; the valves marked with rays pro-
ceeding from an excentric hyaline area, the median ray very
narrow.

In this genus I retain S. Arachne and S. heptactis of De
Brébisson, both having a distinctly areolated structure. The
former has a broadly ovate form, the rays five, and very
excentric ; the latter, according to De Brébisson’s figure,
beirg slightly larger, more orbicular, but still somewhat ovate,
with seven rays, ‘‘ subarcuatis obtusis,”’ which are as decidedly
excentric as those of the other species.

I have now to describe an additional species of great
beauty which I find not unfrequently in Californian guano ;
it has also been obtained from Peruvian (Bolivian) guano by
Mr. George Norman, and it also exists in slides of Peruvian
guano kindly communicated by Professor Walker-Arnott.
Mr. Norman having named it in MS. in honour of our
mutual friend Mr. Ralfs, I gladly give him due precedence.

S. Ralfsianum, n. sp., Norman.—Greatest diameter of the

162 GREVILLE, ON DIATOMACEZ.

valve transversely to the median ray; rays seven, six of them
broad linear, terminating at the margin in a narrow, lunate
fold of the valve. Diameter ‘0018’ to 0070". (Figs. 7, 8.)

In Casifornian and Peruvian guanos.

This noble Diatom is of a pale-yellowish colour, somewhat
variable in outline, but, as a general rule, the transverse
diameter is the greatest, so that one pair at least of the
lateral rays are longer than the median ray, the length of
the latter, as well as the former, being calculated from the
edge of the hyaline area to the margin of thedisc. The rays
are uniformly seven in number, and (excluding the median
ray) of equal width to the very ends, where they terminate
abruptly under a narrow lunate fold of the valve. The
median ray, before reaching the margin, passes along a broad
shallow groove or channel, and terminates in a similar, though
deeper fold of the valve. The rays, though typically some-
what arcuate, are occasionally straight; and although their
excentrical position can always be traced, the fine individual
I have drawn at fig. 7 will serve to show how nearly centrical
they sometimes become, and how nearly the valve may
approach to an orbicular outline. Each ray is bordered
with a row of areole larger than the rest, especially the
median ray, where they increase in size towards its extremity.
The areolation is very distinct, coming out strong and
hexagonal under a sufficiently magnifying power.

In certain characters this species comes near to S. heptac-
tis, viz., in the number of rays, in their being linear and
subarcuate, and in the “angular sinuosity ” of the lines of
the hyaline area; a character referred to by De Brébisson,
although not introduced into his figure. On the other hand
the form of the valve is the reverse of that of S. heptactis ;
as I have never seen it otherwise than broadest in the trans-
verse direction and consequently with the median ray not
the longest. Fig. 8 represents this typical form. A more
important differential character lies in the singular termina-
tion of the rays in a marginal recess or fold of the valve,
which would scarcely have escaped so acute an observer as
De Brébisson had it existed in 8. heptactis. It will be seen
from the figures that the radiating lines of the hyaline area
are curiously ramified; the main lines being sharp and
strong, while an obscure branch proceeds from each angle to
the base of the ray next to it. In bringing these remarks to
a close, I may state that, although size is of little conse-
quence in a rigid diagnosis of Diatomacee, S. Ralfsianum is
a gigantic form as compared with S. heptactis.

GREVILLE, ON DIATOMACEA. 163

AcuNnaNntTHES, Bory.

A. angustata, n. sp., Grev.—Front view of valve very
narrow ; length 0060"; breadth -O001”; striz 24 in :001”.
(PIV ILI, fig. 9.)

In Californian guano.

I regret that I have had no opportunity of examining the
side view of the frustule; but there can be, nevertheless,
little doubt of the species being distinct from any of those
previously described. The striz agree in number with those
of A. subsessilis ; the relative length and breadth, however,
of the valve, as seen in the front view, is so widely different
from the proportions of the species above mentioned, that
the possibility of its being a variety cannot be entertained.

Bippurentia, Gray.

B. longicruris, n. sp., Grev.—Valve on front view with a
central inflation, bearing a solitary, very long spine; angular
processes very long, awl-shaped ; structure minutely granu-
late. (Fig. 10.)

In Californian guano.

After the warning contained in the admirable Monograph
of Biddulphia so recently published by Mr. Roper, not to
multiply species without having seen the frustule under its
various aspects, how shall I venture to transgress so whole-
some a rule in the present instance? All I can say is, that
the frustule of which I now offer a figure is so far removed
from any of the species now established, that I find it quite
impossible to refer it to any of them. B. aurita is its nearest
ally ; but if we adopt the character of that species as laid
down by Professor Smith and Mr. Roper, we find the valve
to possess a central elevation or inflation, on which are
situated two or three or more spines. The angular processes,
according to Smith, are “ horn-like, obtuse, inflated at the
base.’ In the frustule now before me, the central elevation
bears only a single spine, and that much longer and stronger
than it ever occurs in B. aurita ; in fact, it is as long as the
diameter of the entire frustule. Then the angular processes
are also very long, somewhat acute, awl-shaped, without any
inflation at their base. These distinctive marks, which, being
as well seen in the front as in the side view, will, I trust,
justify me in giving it at least a provisional place until ma-
terials for a more perfect description shall be obtained.

B. Roperiana, n. sp., Grev.—Valve elliptical-oval, with a
central elevation, which, as seen in the front view, is depressed

164 GREVILLE, ON DIATOMACESE.

or sometimes bilobed, punctate, unarmed ; angular processes
very short and obtuse, largely inflated at the base; con-
necting membrane with rows of minute dots parallel with
the suture of the valve. (Figs. 11—13.)

Monterey, California ; Gear ge Norman, Esq. In Cali.
fornian guano.

This species appears to be removed from all the varieties of
B. aurita by the absence of spines, and by the very depressed,
often two-lobed central elevation of the valve. It differs also
in the more distinctly punctate structure; in the more con-
spicuous rows of dots in the connecting membrane, and in
the angular processes being much shorter and more obtuse or
rounded ; they are, indeed, sometimes so short, as to scarcely
rise above the level of the central elevation, in which case
the process and its inflated base appear almost like two
lobes of the same organ (see fig. 12). The species has,
like some of its congeners, a large range with regard to
size, and the punctate structure is fine or coarse in proportion
to the development of the frustule. Fragments of indivi-
duals have occurred to me considerably larger than those I
have represented. At all times it appears to be a much
larger form than B. aurita.

Since these observations were written, Mr. George Norman
has kindly sent me a shde of Diatomacee, from Monterey,
which he believes to have been collected from sea-weed. It
contains, besides Biddulphia turgida and other things, several
frustules of B. Roperiana, agreeing minutely with those I had
found in the guano.

I have much pleasure in dedicating to the acute and judi-
clous expositor of the genus Biddulphia this very beautiful
new species.

CRrESSWELLIA, Arn. and Grev.

In the ‘ Transactions of the Royal Society of Edinburgh,’
vol. xxi, I have assigned the reasons which led my friend
Professor Walker-Arnott and myself to propose a new genus
for the reception of the Diatom we there described and figured
under the name of Cresswellia turris. I may here briefly
state that Ehrenberg, having found that his original definition
of the genus Py«idicula (‘ Die Infusionsthierchen,’ p. 165)
required revision, constituted three sub-genera, Diciyopyzis,
Stephanopywis, and Xanthopyxis (‘ Bericht. der Berl. Akad.,’
1844, p. 262, et seq.) It must be admitted, however, that
so very litthé was known of the forms thus associated, that
these sub-genera resembled artificial sections, adopted for
mere convenience, rather than well-defined genera; and

GREVILLE, ON DIATOMACES. 165

Kiitzing seems to have been under this impression, when he
reunited the whole under the old name (‘Sp. Alg.,’ 1849).
But this proceeding had only the effect of perpetuating for a
time the union of a number of objects whose history and
habits continued to be enveloped in mystery, and many of
which had manifestly no real affinity with each other. Were
we now constrained to select one of Ehrenberg’s sub-genera
as aresting-place for Cresswellia turris, and another species to
be immediately described, we should have to take Stephano-
pyxis, of which the author gives the following character :

“ Pyxidicule generis bivalves turgid aut subglobosz
forme, que valvularum teste structura cellulosa msignes
sunt et denticulorum, aculeorum aut membrane coronam in
media quavis valvula gerunt in hoc Pywidicule subgenere
colliguntur.”

Now this character was prepared with special reference to
certain existing forms; and if we examine these forms, we
shall perceive how indefinite the character becomes. Sz.
appendiculata (‘ Mikrogeol.,’ tab. xviii, fig. 4) is distinguished
by the valves being furnished with only a single short blunt
horn “extra medium posito.” St. cristata (l. c., tab. xvii,
fig. 6) appears to have a sort of limbus surrounding the
whole frustule,—nothing in the shape of a “corona” of
any kind. St. aculeata is said to be “undique parvis
aculeis hispida, nec cellulosa.”” With regard to the only
remaining species, St. diadema, of which no figure has ever
been published, it would appear to come generically nearer
to our Cresswellia turris, but we are not aware that it has
been seen in a perfect state or whether the frustules are
united in chains. Kiitzing, in his generic character, says
positively of all the Pywidicule that they are “ non-con-
catenata,”’ thereby excluding Cresswellia. Upon the whole,
therefore, seeing how ill the species of Stephanopyxis agree
generically among themselves, and that we do not even know
which of them was regarded as the type, we think that by
establishing the genus Cresswellia we have adopted the only
course open to us. It was impossible for us to place our
new Diatom in Stephanopyxis without altering the character
to such an extent, that while the new species was admitted,
all those for which it was actually constituted would be
either excluded, or at best doubtfully retained. Such a
proceeding would have been, of course, inadmissible.

C. turgida, n. sp., Grev.—Frustules cylindrical oblong,
obtusely truncate; connecting processes dilated ; length about
0032”; breadth :0021”; areolee 11 in ‘001”. (Fig. 14.)

166 GREVILLE, ON DIATOMACE.

In Californian guano.

This very interesting species is nearly related to C. turris,
but differs in the larger, more truly cylindrical and truncate
frustules, and in the considerably smaller areolation; the
areolz in C. turris being 7, in C. turgida 11 in 001”. In
both they are beautifully hexagonal. At the time my
drawing was made I had only met with isolated frustules,
but I have since seen them in union. The colour (in balsam-
mounted slides) is very pale yellowish-brown; and the
substance is so transparent, that it 1s easily overlooked.

C.? ferox, n. sp., Grev.—Frustules oblong; valves sub-
globose, campanulate, thin and hyaline at the suture;
connecting processes spine-like; areolation large, hyaline,
walls of the areole passing at the angles into short spinous
processes, so as to give a hispid character to the frustules ;
length :0020” to :0025"; breadth -0012” to -0015”"; areole 5
im, OU (hice: loro.)

In Californian guano.

Single valves of this species are common, generally pre-
senting themselves in a vertical position, in the form of a dise,
when the connecting processes are lost sight of, but the
campanulate or expanding margin is well seen. Occasionally
entire frustules are observed ; but I have only twice had an
opportunity of examining them in connexion. The species
is so very different in habit from the other Cresswellie that
it may eventually prove to belong to a distinct genus. The
comparatively very large and strong areolation, suggestive of
Polycystinee rather than Diatomacee,—the spine-hke con-
necting processes, and the expanded margin of the valves
forming a sharp keel at the line of suture, indicate other
affinities. There seems also to be a striking difference in
the substance. C. turris and turgida have a more flexible
appearance, the latter especially; while the present form
is hyaline, and rigid, as if it would be readily fractured
under pressure. The most remarkable feature about it,
however, is the hispid character of the frustule when seen in
profile, and which at first sight is exceedingly difficult to
account for, as there are no traces of genuine spines. A
minute examination has brought me to the conclusion that
the effect is owing to the walls of the hexagonal areolz being
produced at the angles into spine-like processes.

After a careful study of the very brief characters given of
the Pyzidicule by Ehrenberg and Kiitzing, Iam quite unable
to identify the species now described with any one of them.

167

Metuop of Creanine Diatomaces.
By Artuur M. Epwarps, New York, U. S.

Tuovucuthere are many methods that have been devised for
cleaning deposits of Diatomacez, none has proved to be per-
fect in all its details; that one that appears nearest so being
that which I give below: It is well known that the ordinary
method given in the books, of boiling in nitric acid alone, is
extremely unsatisfactory, as it does not remove all the or-
ganic matter that may be present in the deposit, and this
is more particularly apparent when treating guanos for the
purpose of obtaining the forms contained in them. Some
few years back Bailey published, in the ‘ American Journal
of Science,’ a plan which seemed to meet all the wants of
microscopists. ‘This method was by removing all the organic
matter through the agency of sulphuric acid and chlorate of
potassa. In this process, however, at first a bisulphate of
potassa is formed, which, when we attempt to wash it out
with water, is converted into neutral sulphate and free sul-
phuric acid. The neutral sulphate of potassais a salt soluble
only with difficulty, so that it becomes almost impossible to
remove it entirely and leave the Diatomacez perfectly clean.
It is to obviate this trouble that the following method has
been devised, and, as it has beenin constant use for over two
years, with invariable success, it can be confidently recom-
mended to microscopists.

It was first used in the case of guano, about the most
difficultly manageable of all Diatomaceous deposits, and,
therefore, will be given here as used for that substance, the
difference of manipulation necessary to be used when it is
required to clean earths or tidal muds being very slight and
sufficiently apparent without mentioning them here.

The guano is freely exposed to the action of the air during
several days or weeks, according to whether it be rich in
moisture and organic matters or otherwise, and also according
to the amount of dampness present in the atmosphere; thus,
in summer it requires but little exposure to bring the guano
to a proper state, whilst, in winter, it will require several
weeks. It is thus exposed until it has become perfectly dry,
and crumbles to a fine light fawn-coloured powder. It is
then washed several times in water that has been carefully
filtered through chemists’ filtering paper. This filtered, is

i
68 EDWARDS, ON CLEANING DIATOMACES.

found to answer all the purposes of distilled, water, which is
much more troublesome to procure, and then only by a
tediously slow process. Every time it is washed, the water
is allowed to stand on it for at least twenty-four hours. It is
thus washed until the water takes up no more salts and runs
off perfectly clear. The two or three last washings may be,
with advantage, made with boiling water.

After every washing, we must make sure that all the guano
has settled, that none of the finer forms may be carried over
with the water, when it is poured off, and lost. When the
washing is complete the guano is intreduced into a capacious
chemists’ beaker-glass, and there is poured on it sufficient
chlorohydric acid to cover it to the depth of an imch and
a half, when it is boiled for about an hour. It is then well
washed with filtered water, and nitric acid made to replace
the chlorohydric. The boiling of the nitric acid is now kept
up until no more red fumes are given off, and the deposit is
again well washed several times. ‘Thus far this process is the
same as that recommended in the books, but the undissolved
portion is not colourless; we have, therefore, to proceed with
the following manipulations.

- The deposit which now remains, after the boiling in acid,

is well washed until the water comes off perfectly clear and
almost free from acid; it is then covered to about the depth
of an inch with sulphuric acid, and boiled until all the organic
matter contained in it is charred, which is known by its
turning black. Sometimes, however, the organic matter is
in such small quantity that it hardly shows signs of colora-
tion. When such is the case, it is always better to boil the
acid for a short time before proceeding to the next step in the
operation. The fumes given off in this and the next stage of
the process are extremely unpleasant in odour and effects, so
that care should be taken not to inhale any more of them
than can possibly be helped, as they are apt to inflame the
air-passages and cause severe sore throat. The best method
is to conduct this portion of the process in the open air, or
under a chimney haying a good draught.

Whilst the sulphuric acid is undergoing ebullition, finely
pulverized chlorate of potassa in very small quantities is
added from time to time, always allowing the violent action
resulting from the introduction of one portion to completely
subside before another is introduced. During this portion
of the process the hand should not be exposed to the vapours
given off, as they will act on and ‘corrode the skin; the
chlorate may be introduced by means of an ivory spatula—a
metal one would be corroded. The heat is kept up all the

EDWARDS, ON CLWANING DIATOMACES. 169

time until sufficient chlorate is supposed to have been used,
which is generally known from the deposit becoming per-
fectly white. Great care must be taken to add the chlorate
only in small quantities and at distant intervals, or a violent
explosion will result, shattering the vessel and throwing the
boiling acid over the clothes and person of the operator.

A quantity of filtered water in a boiling state is now pro-
cured, and the sulphuric acid and deposit poured into it in
small portions. If the water were poured into the acid, the
heat generated would be so intense that there would be
danger of rupturing the vessel. After all the deposit has
been introduced into the water, the boiling is kept up for a
short time, and then it is allowed to settle. Thus far this
process is the same as that proposed by Bailey, but is, as I
have before remarked, incomplete, from the formation of sul-
phate of potassa, which cannot be entirely removed by water
alone.

To complete the cleaning, we allow the deposit to settle,
and then pour off the supernatant liquid. Sufficient nitric
or chlorohydrie acid is then introduced to cover the deposit
to the depth of about an inch, and it is boiled. ‘This acid
decomposes the sulphate, and forms avery soluble salt, which
is easily removed by frequent washings with filtered water.
Phe remaining deposit is washed with filtered water until a
drop of the liquid does not leave any crystals om evaporation
on a plate of glass.

It now consists of sand and Diatomacez only, and should
be preserved in a mixture of alcohol and water, which prevents
the Diatoms matting together, as they are apt to do, and
also will not allow of the formation of Confervz, which form
in most quiet water.

170

What are Marine Diatoms? By G. A. Watxer-Arnort,
LL.D.

In the Preface to the late Professor Smith’s second volume
of ‘British Diatomacee,’ at p. 25, we find—“I feel per-
suaded that a marine species will not flourish under fluviatile
influences, nor a fresh-water form long survive when trans-
ferred to a marine habitat. Still further, I believe that
certain species are far more special in their tastes, some
selecting mountain-torrents, and others fixing their habitation
in boggy pools or alpine lakes; some being exclusively
littoral, and others found only in the deeper parts of the
sea.” As a mere speculation, this statement is of little con-
sequence, but Smith applies it to the determination of
species, when other means fail; thereby employing it, not as
a theory, but as an ascertained fact.

In general, the result at which I have arrived corroborates
the theory in many particulars, but by no means to the full
extent. A truly fresh-water species may be carried down
to brackish water, and survive there; but the circulation is
more languid, and consequently the amount of silex deposited
smaller, so that, although the distance of the striz may be
much the same, they become more faint. If the same
species be carried into pools still more of a marine character,
it is either killed or grows; but, in the latter case, the
circulation is very languid, the silex almost or wholly absent,
and the formerly conspicuous striation is now extremely
obscure. I have very great doubts if Fragilaria striatula be
not, on that account, a degenerated form of F. capucina.
In the same way, truly marine species, when in brackish
water, have their silex less in quantity and striz less visible,
and in fresh water are either killed or grow very languidly,
and become scarcely siliceous. But there are Diatoms which
are peculiar to brackish water, and are not found in a good
state either in the open sea or in fresh water. Epithemia
musculus may be cited as one of these, and unquestionably
there are others, as Navicula amphisbena and Nitzschia dubia,
which flourish as well in brackish water as in fresh water
remote from the sea.

As to Diatoms occurring in the deeper parts of the sea, that
is no doubt true; but it does not appear to me that any
species can increase much without access to more atmo-
spheric air and solar ight than can be obtained there; and,
consequently, that most of what are found in dredging have
been conveyed there by the receding tide from our own, or

WALKER-ARNOTT, ON MARINE DIATOMS. 171

by ocean currents from a very remote, shore. Even fresh-
water species are deposited in that way. I have found,
while dredging in fifteen or twenty fathoms, off the coast of
Arran, at the mouth of the Clyde, Eunotia triodon, Himan-
tidium pectinale, and Navicula rhomboides; and frustules
of the last two have also occurred to me in rocky pools near
low-water mark. Dr. Dickie* has given a list of several
fresh-water species which he met with m Aberdeen Bay, in
the stomachs of Ascidia, in from twenty-five to thirty fathoms,
and at five to six miles from land: among these are Himan-
tidium pectinale, Tabellaria flocculosa, Cocconeis pediculus,
&e. I have occasionally seen detached valves of Orthosira
arenaria in dredgings; but, deceived probably by the
locality, Dr. Gregory, in his paper on ‘ Clyde Diatoms,’ fig.
44, has reproduced it as a new species of Melosira (?) or
Coscinodiscus (?), he is uncertain which.

The mere finding of a species in the sea is therefore no proof
of its having grown there; so that other means must be resorted
to before asserting that such specimens must form a species
distinct from an analogous one occurring in Alpine streams,
or elsewhere in fresh water.

Lewes, in Sussex, where Smith principally made his
observations, is peculiarly unsuited to solve these difficulties.
The influence of the tide is there conspicuous, and when a
species is rare, and confined to only one locality, it is quite
impossible to deduce whether it is a brackish-water one, or
a marine form carried there by the tide, or a fresh-water
one swept down from the higher grounds. When, therefore,
only one or two localities are indicated by Smith, and
these entirely about Lewes, or in a similar place, the pecu-
liarity of the water most congenial to that Diatom must be
held to be still m doubt. A few instances of this may be
mentioned.

Nitzschia dubia is stated by Smith to occur only in brack-
ish water. I have it from the Queen’s Park, Edinburgh, and
from several places about Glasgow, South Wales, &c., at a
considerable altitude above the level of the sea; so that,
although seemingly to grow equally well where the water is
partly saline, it certainly affects truly fresh water. Nitzschia
Brebissoni is stated by Smith to be found in fresh water (he
. found it only at Lewes) ; but his slides contain many marine
species (as Nitzschia sigma, Navicula minutula, Tryblion. scu-
tellum, gracilis and punctata, Bacillaria paradoxa, &c.) as well
as fresh-water ones (as Nitzschia sigmoidea, Navicula cuspidata,
Nav. ambigua, &c.) Smith drew his conclusions from a.

; * « Annals of Nat. Hist.’ for 1848, vol. i, p. 324.
VOL. VII. he

172 WALKER-ARNOTT, ON MARINE DIATOMS.

different source: he had obtained from M. De Brébisson
Sigmatella Brébissoni of Kiitzing, a truly fresh-water spe-
cies; and on the supposition that this was the same, he
applied the name Brébissoni to his species from Lewes,
assigning it a fresh-water habitat; but De Brébisson’s (and
as it was he who discovered it at Falaise, and sent it to
Kiitzing, so his specimens form a correct index to both Syne-
dra armoricana and Sigmatella Brébissoni of Kiitzing) proves
to be a mere variety of Nitzschia sigmoidea; while Smith’s
N. Brébissoni was actually quite unknown to De Brébisson
or Kiitzing. That it isa truly brackish-water species is further
proved by its having been found in such situations at Hull by
Mr. Norman. I have the same, unquestionably, in a slide
got from the drip from the walls at Chester; but it is very
scarce there, and may have been carried inland by spray and
storms, in the same way as Navicula pusilla, and even N.
Jenneri, are sometimes conveyed to a distance from the sea,
and found among mosses on trees with a corky or cracked
bark. Nitzschia Tenia is said to be from “ brackish water :”
I have it from several such localities; but I have collected
it also from clay-pools in brick-yards, near the Botanic
Garden of Glasgow, at an elevation of about 80 feet above
the sea. On the other hand, I have found N. acicularis
sometimes in brackish water; so that both are probably
fresh-water species, and carried down by streams.

Cyclotella punctata, Sm., is stated to inhabit fresh water
at Wisbeach. In his slide are chiefly fresh-water species,
and amongst them Synedra minutissima, for which Smith
assigns a fresh-water locality only, but which I uniformly
find within the influence of the tide. Swriredla ovata is here
copious, but that Diatom is more abundant in brackish than
in truly fresh water. The same species has occurred to me,
but very rarely, in a preparation from Breydon, Norfolk
(collected by the late Mr. Wigham), along with Cyclotella
Kitzingiana, Pleurosigma strigilis, Amphora affinis, and some
others not found in fresh water; there are, however, some
fresh-water species mixed. This has been more recently
and copiously found by Mr. Norman, of Hull, in the
Market Weighton Canal, at the end near the sea, and which
is occasionally supplied from the sea. Here, although the
fresh-water species predominate, there are other forms also,
as Synedra acicularis, &e., which indicate its brackish
tendency. This species appears to me to be a genuine
Coscinodiscus, very closely allied to C. subtilis, and probably
with C. Normani, Grev., and some others, forming only one
species, varying according to the saline nature of the water,
and other incidental circumstances. It is the middle of the

WALKER-ARNOTT, ON MARINE DIATOMS. 173

valve only which is undulated, a character which often dis-
appears after the valves have been separated from the con-
necting zone by beimg boiled in acid; the margin and the
connecting zone itself is not undulated, as in several genuine
species of Cyclotella.

Amphiprora paludosa is said by Smith to be found “in
fresh or slightly brackish water ;’ and here I shall suppose
his figure to indicate the form intended ; this has a peculiar
indentation on each half of the valve at the place where the
ala or keel meets the body of the valve; but this indentation
is not noticed in the text, and does not seem to have been
considered of any importance by Smith. I have no slide
from him; but I have examined the same form from Wool-
wich, Hull, the coast of Norfolk, Ayrshire, &c., and invaria-
bly accompanied by marine Diatoms. I therefore consider
it, like all others of the genus, as peculiar to salt or at most
brackish water. I have before me also a form without the
indentation, and with striz (sometimes very obscure) on the
body of the valve; which is thus intermediate between the
figured A. paludosa and A. alata on the one hand, and between
it and A. duplex on the other: so that I cannot avoid drawing
the conclusion that these four forms belong to one natural spe-
cies, recognised by the alate carina, and tendency to twist when
the valves are separated and either dried or put into balsam. A.
Ralfsit has the same tendency to twist, but the keel is not alate.
In the same way A. lepidoptera represents those that have an
ala but do not twist, while A. vitrea and elegans conjoined form
a fourth species, without an ala, and with no tendency to
twist. All other species of the genus may, as appears to me,
be reduced to one or other of these.

Amphora minutissima is said to be always parasitic and from
fresh water ; but Mr. Okeden has found, in South Wales, two
forms of apparently the same species: one in a salt-water
marsh, parasitic on Nitzschia sigma ; the other in fresh water,
and not attached to anything.

Coscinodiscus minor of Smith is stated to be from fresh
water; but what he had described he afterwards satisfied
himself was only the detached valves of Melosira nivalis.
Kiitzing’s (and I believe Ehrenberg’s) species of the same
name is from the sea or brackish water, and is not uncommon
at the mouth of the Clyde, and on many parts of the east
coast of England: it is figured in Gregory’s paper on ‘ Clyde
Diatoms,’ as the 8.V. of his Orthosira angulata ; but certainly
does not belong to it, for Orth. angulata in no respect differs
from Orth. marina. I have one or two gatherings of Cose.
minor from Cumbrae (from Mr. Hennedy), with the valves
copious, but no trace of any Orthosira.

174 WALKER-ARNOTT, ON MARINE DIATOMS.

Eunotia is strictly a fresh-water genus. I may here
remark that recent observations on HE. diadema has convinced
me that the character I proposed (‘ Micr. Journ.,’ vi, p. 202)
for distinguishing Hunotia from Himantidium is not tenable :
I must have been deceived by examining specimens at the
period when the connecting zone was at its minimum, and
inconspicuous. I am now quite satisfied that specimens may
be found in perfect accordance with Smith’s figures.

Epithemia is chiefly a fresh-water genus, although most of
the species grow equally well im brackish water. It is also
a truly parasitical one. Some species are no doubt found,
not on filiform alge, but among the gelatine of Hemato-
coccus and others of the Protococcee, to which they seem to
attach themselves. H. musculus I have never seen, except:
in salt marshes to which fresh water has access. . rupestris
is said to be from fresh, and H. Westermanni from brackish,
water; but this is lable to doubt, for EL. Westermanni of
Smith can scarcely be distinguished from short forms of #.
rupestris, and may have been carried down by streams, or be
one of those that grow in both places. Thisis not H. Wester-
manni of Kiitzing, a species which I have seen parasitic on the
leaves of Zostera from the Baltic. E. musculus of Smith
appears to be composed of two species, one which he has
described in the text as having “striz 40 m ‘001,” and
which I have in the same slide with H. Westermanni, Kutzg.,
and is the EH. musculus of Smith’s slides from the 8. of France
(May, 1854); the other, or true EL. musculus, has distinct
moniliform striz, and is that figured by Smith. The
synonyms of the whole species are much confused in the
‘Synopsis.’ H. constricta of Smith is certainly not that of De
Brébisson, which is a much smaller species, destitute of the
anterior keel to the valves (by which Smith’s is distinguished),
and more allied to H. Westermanni of Smith. LE. alpestris of
Smith’s ‘Synopsis,’ from Katefield, is not the species of that
name distributed in slides by Smith, which latter wants the
large foramina, and is that form of L. zebra called EL. librile by
Ehrenberg. E. argus, EF. ocellata, and E. alpestris of the
‘Synopsis’ are three varieties of H. ocellata (such is the
oldest name), while E. longicornu is the sporangial state of
the same. KH. Hyndmanni, Sm., and Eunotia Luna of
Ehrenberg’s ‘ Mikr.,’ tab. xv a, fig. 58, are obviously one
species; but Ehr. ‘ Mikr.” tab. xxxiii, xii, fig. 15, from
Oregon, appears very different. The specific character given
of HK. Luna by Kiitzing refers to the Oregon species only.
In justice to Mr. T. Comber, of Liverpool, I ought to state
that the preceding observations on this genus are the
combined deductions arrived at by him and myself. I know

WALKER-ARNOTT, ON MARINE DIATOMS. 175

of no one who has paid more attention to the species of Hpi-
themia than Mr. Comber, and much wish that he would give
to the public a monograph of them. He is the only one who
has studied with care, not merely the F.V. and S.V., but
also the vertical view, corresponding to a transverse section
of the frustule, which yields characters of some importance.

Tryblionella gracilis is stated to be from fresh and brackish.
water. It usually occurs in the latter, and these specimens
are much larger and finer than the others; but it certainly
is found in various localities at a considerable elevation above
the sea. Indeed at one time Smith considered this form dis-
tinct, and named it 7. minor ; it is more oval than the littoral
form, and is scarcely distinguishable from T. levidensis, except
by the finer striation. Dr. Gregory has published a 7. apicu-
lata,* which he had from Cumbrae, and felt doubtful whether
to consider a marine or fresh-water species. This is very
common on all the coasts of Scotland and England, and was
considered by Smith, when sent to him by me several years
ago, a slate of Nitzchia dubia, var. 3. It is alluded to in
‘Micr. Journ.,’ mi, p. 809. It is certainly a brackish-water
or marine species.

Navicula Smith (elliptica, Sm. ‘Syn.’) and N. elliptica,
K. (ovalis, Sm. ‘Syn.’) are very closely allied, and would
have been probably united, were the one not peculiar to
fresh water, the other to the sea; the striation of the
former is coarser. Now, taking striation as our guide (and
here I regret to differ from Smith, and think striation, or
any microscopic difference, unsupported by more natural
characters, as a very fallible one), 1 have been supplied by
Dr. Dickie with a series of gatherings made last December
in acave at Skateraw, on the Kincardine coast, which are
very puzzling. I understand the cave to be far beyond the
reach of the tide, although during great storms the spray
may be carried to it. Near the entrance of the cave is
N. Smithii, accompanied by Orthosira spinosa and Himan-
tidium gracile. A little further in are N. Smithit and
N. elliptica, much mixed, and Orthos. spinosa; further in, a
gathering was made composed of N. elliptica, Epithemia ru-
pestris, and E. Westermannit, Sm., so varied and mixed as to
be undistinguishable ; Cocconeis Thwaitesii, Denticula obtusa,
Odontidium Tadellaria and mutabile (both small). I believe
that the third sample was got on the opposite side of the cave
from the second, but am not quite certain; I have not ob-
served in it either N. Smithii or Orth. spinosa. At the
further extremity of the cave Orth. spinosa was got quite

* «Trans. Micr. Soc.,’ vol. v, p. 79, tab. i, fig. 43.

176 WALKER-ARNOTT, ON MARINE DIATOMS.

pure. Doubts are thus thrown on the distinction of the
species, or on the fresh- and salt-water localities assigned.

Nav. amphisbena occurs in fresh water, brackish water, and
in the sea. The first has the extremities capitate, and con-
spicuously produced ; the second much less so (it is 3 of
Smith). The third is smaller, with the ends scarcely at all
produced, and is N. brevis of Greg.; it was named in March,
1854, by Smith, WN. retusa, n. sp. (before De Brébisson’s
other species of that name was published), but I afterwards
satisfied him that it was a mere variety of N. amphisbena, and
it is therefore not described in the ‘ Appendix.’

Pinnularia gracilis has a fresh-water habitat given; but
a form of it, with a shorter beak, is not uncommon in
brackish water. This was at one time considered by Smith
a new species, and called by him P. curta; it is, however,
omitted in the ‘ Appendix.’

Stauroneis pulchella is beyond doubt marine ; but there are
two forms so different that some think them different species,
and even refer them to different genera. St. pulchella,
properly so-called, is got in all our rocky pools, and has the
stauros (by the way, I wish some more correct name were
devised, for stauros is not the transverse beam of a cross, as
is here intended, but the whole cross itself) cuneate, or
“ dilated towards the margin ;” and the frustule on a F.V. has
the angles rounded. On the other hand the second form
occurs in sand-gatherings, has the angles on a front view
sharp, the ends of the frustule appearing truncate; and the
stauros (?) is a large circular blank spot around the nodule.
The striation in both is much the same, and different from
what is usually observed in this or the allied genera; but St.
pulchella is of atawny colour ; the other ofa dark bluish green.
This latter form De Brébisson wrote me (February 21st, 1858),
he proposed to call Navicula angulata : he had first found it in
1852, and considered it, with N. pectinalis and retusa, as a
group very distinct from the other species. As this group is in
great confusion, the following observations may not be unin-
teresting. It is not to me quite clear on what De Brébisson
originally bestowed the name of N. pectinalis ; what Smith
received from him, and supposed to be so, I have reason to
think was N. retusa, of which Smith only knew the F.V.,
and in that state it is almost undistinguishable from JN.
pectinalis of Smith’s ‘ Synopsis.” On February 12th, 1858, De
Brébisson was disposed to consider the above N. angulata to
be his N. pectinalis ; but a few days after relinquished that
view, and formed the opinion that a curious and very distinct
species (which he since had called Amphora? quadrata)

WALKER-ARNOTT, ON MARINE DIATOMS. 177

might have been intended; this, which has two striz at the
central nodule, much stronger and more distinct than the
others, had certainly not been seen by Smith on the piece
of mica he had received, if there at all. When Smith got
the specimen from Saltcoats, he found the F.V. to accord
with what he was led to think N. pectinalis, and as the valve
was linear-elliptical, he has so described it in the 2d vol. of
the ‘ Synopsis,’ p. 92; but his N. pectinalis was unknown to
De Brébisson; it is a rare species, and as yet known to me
only from the coast of Ayrshire and island of Cumbrae.
Unfortunately he has there conjoined with it another form
which I first found in Ayrshire (but soon after in Arran,
and I have since got it from the west coast of England) ; this
is much smaller, with broadly linear truncate valves, and
radiating central strie. De Brébisson, in 1854, published
his N. retusa, a species with linear valves, and which I feel
certain, as already stated, was the one which was sent to
Smith, in 1852, as N. pectinalis of De Brébisson ; this is very
common in the mouth of the Clyde, and has been sent me
from several other places considerably distant from each
other ; itis adopted by Smith in his ‘ Synopsis.’ There results
from this, if my views be correct, that N. pectinalis, Sm., is
not that to which De Brébisson first gave the name;
and that the one intended by De Brébisson is probably that
which he afterwards published as N. retusa. The other two
species (viz., the small one confounded with N. pectinalis by
Smith, and the one at one time called Amphora ? quadrata by
De Brébisson) are as yet undescribed ; the latter was first, in
this country, found on the Northumberland coast by Dr.
Donkin, and afterwards copiously at Tynemouth by the Rev.
R. Taylor; I have since got it from Cumbrae in the Clyde,
and I have seen it from Teignmouth in S. Devon, but very
sparingly in both these localities. To this group also belongs
Pinnularia rostellata, Greg. (the F.V. can scarcely be dis-
tinguished from that of Nav. retusa) ; I do not see how this
differs from Nav. apiculata, De Bréb.

Synedra pulchella and minutissima are said to grow in fresh
water, S. gracilis and acicularis m brackish. I find no
difference in that respect ; all when in fresh water are got in the
mouth of streams ; I never met with any of these at a consider-
able elevation, nor, indeed, beyond the occasional if not con-
stant rise of the tide ; between these four reputed species I find
no certain marks of distinction. 8S. fasciculata is said by
Smith to grow only in fresh water; while Agardh,
Kiitzing, Greville, and others make it marine; both parties
are correct, because they do not mean the same species.

178 WALKER-ARNOTT, ON MARINE DIATOMS.

What Smith had in view is S. parvula, Kiitz. (from which
S. parva, Kiitz., from De Brébisson, scarcely differs; while
S. parva from the Gulf of Venice appears to be S. énvestiens,
Sm.) The S. fasciculata of Kiitzing seems to be a common
variety of S. affinis with blunt valves; Agardh’s Diatoma
fasciculatum is partly S. affinis and partly S. arcus of Sm.
(not Kiitz., which seems to be a state of S. Gailloni) ; while
Exilaria fasciculata, var. a, of Greville, is S. radians, and his
var. (3 a mixture of S. arcus, S. affinis, and S. pulchella.

Doryphora Boeckii is stated to be marine; but Smith wrote
me afterwards that he had doubts on the subject ; when I
have found it in Arran, it was growing intermingled with
Synedra pulchella, S. minutissima, and Eunotia (also a species
of Synedra) arcus, Sm., all of which were reputed fresh-
water species. I have just mentioned that the first two are
found at the mouths of rivers or streams, but not beyond
high-water mark, and D. Boeckit is probably in the same
predicament; I have, however, specimens from Norway
(from Mr. Norman, of Hull) in which it is mixed only with
marine species.

The last to which I shall at present allude is Homeocladia
filiformis: this is said to be from brackish water, and it is occa-
sionally found there; but it grows abundantly on fresh-water
algeze in the Monkland Canal, near Glasgow, a canal which
is at the elevation of about 165 feet above the level of the sea,
and to which sea-water cannot possibly have access. I cannot
call the water there either sweet or fresh, for it is both dirty
and offensive to the nasal organs; but it contains no salt.

It thus appears that although the statement made by
Smith, and quoted at the commencement of this paper, may,
on the whole, be correct in theory, it is of very little prac-
tical value, and may lead incautious observers to very in-
accurate conclusions in the distinction of species. At pre-
sent, and until more facts are collected, it may be held a
safe rule that when a whole genus is peculiar to fresh water
with the exception of a single species, and that exceptional
species is accompanied by some fresh-water forms, it ought
to be held also as belonging to fresh water, or at most to
brackish water; and that when the genus is marine, with
the exception of one species, this, if accompanied by any
properly ascertained marine or brackish-water Diatoms, may
be regarded also as a marine or brackish-water species: and
although a mere gathering may not clear up the point when
ditches, canals, and sluggish streams are in question, a slight
inquiry as to how these are fed may contribute much
towards it.

179

On some of the Rarer or Unprscripep Species of Dtaro-
MAcEm. Part I. By T. Brieurwe tt, F.L:S.

Iv is my purpose to give in this and some following papers
descriptions of some of the many undescribed or unfigured
species of Diatomaceze, chiefly marie, which still are found
in our cabinets ; illustrated by Mr. Tuffen West’s excellent
figures, they will, I trust, be acceptable and useful to algo-
logists.

1. Kunotia eruca.—vValve slightly arcuate, from three to
five or six flexures or undulations above and below; extre-
mities slightly produced, striated. Varies in length from ‘0018,
with three flexures, to ‘004 with five flexures. Strize 20 in
001. Amphicampa eruca (Ehr., ‘ Mikr.,’ Pl. xxxi, F. vii).
Fresh-water lagoon, near Melbourne, New South Wales ;
Mackie. (Pl. IX, fig. 1, and fig. 1a.)

2. Cocconeis coronata, n. sp.—Valve oval, slightly con-
stricted at the extremities, stout marginal band, with from
thirty to thirty-two transverse canaliculi; disc striated,
moniliform ; strie 15 m -001. Valves 002 long by -0014
broad. Shell cleanings. West Indies. (Pl. IX, fig. 2.)

3. Cocconeis fimbriatus, n. sp.—Oval, margin fringed with
a band indented internally, disc striated, with lines of dotted
strie. Corsican Alge. (PI. IX, fig. 3.)

4. Campylodiscus striatus, Ehrenb.—Disc in the middle
part smooth, with a double series of parallel canaliculi on
each side, eleven in the smaller to twenty in the larger spe-
cimens. Kitzing, Species ‘ Alg.’ p. 33, No. 11. Vera Cruz.
(Pl. IX, fig. 4.)

5. Surirella limosa, Bailey.—V. broadly ovate, acuminate,
faintly punctato-striate. Canaliculi seventy-five to eighty,
short and indistinct, not reaching more than 1-6th across the
valve, leaving a large blank centre. Length ‘01 by -045 in
breadth. Strize very indistinct, 22 in -O01.

Professor Bailey, MS.? Thisspecies was, Mr. Tuffen West
thinks, sent to Professor Smith, with this name.

New Zealand, Mackie. Mud, Hudson River, New York,

180 BRIGHTWELL, ON DIATOMACES.

N.A., Professor Bailey. Mr. T. West has seen a specimen
from Thames mud. (PI. IX, fig. 5.)

6. Stauroneis fulmen, n. sp.—F. V. oblong; V. lanceolate
acute. Margin with a marked double inflexion on each side.
Stauros very slightly, if at all, dilated towards the margin of
the valve. Striz fine and sharp, 22 in ‘001. Length from
"008 to -015.

Fresh water, Melbourne, N. 8. W., Mackie. (Plate IX,
ne=.60, V.; 60, F. V.)

7. Pleurosigma longina, P. Smith.—V. lanceolate, flexure
moderate, extremities greatly elongated; acute; colour faint
straw ; striz transverse, 36 in ‘001; length from -02 to ‘025.

Arctic Regions, Dr. Sutherland. (Pl. IX, fig. 7.)

8. Odontidium speciosum, n. sp.—Valve subcruciform or
rhomboidal, angles rounded, naked, costz short, distinct,
sixteen on each side. (Pl. IX, fig. 8, a, side view; 4, front
view.) Shell cleanings.

9. Odontidium punctatum, n. sp.—Valve subrhomboidal,
angles pointed, cellular, obscurely punctato-striate, without
cost. (Pl. IX, fig. 9.) Shell cleanings.

10. Odontidium Baldjickii, n. sp.—Valve ovately rhom-
boidal. Costz about twenty on each side the median line,
distinct, reaching nearly to, but leaving a linear open space
down the centre. (Pl. IX, fig. 10).

From a clay or earthy deposit found on bones imported
from Baldjick, near Varna, Mr. Norman.

The species last described are allied to O. Harrisonii of
Professor Smith, and we refer to his observations (‘S. B. D.,’
vol. i, p. 18), as to their true position in a systematic arrange-
ment.

11. Rhabdonema mirificum, Professor Smith.—“ Septa
with three to twelve irregular perforations.”

See Dr. Walker Arnott’s observations, ‘Mic. Journal,’
vol. va, p..92. (Pl. IX, fig. 11)

12. Triceratium (?) dubium, n. sp.—Valve clypeate, punc-
tate, with six rounded projections, the lower one elongate.

Mauritius. (Pl. IX, fig. 12, a, side view; 6, front view.)

We place this species (which is not of unfrequent occur-
rence) provisionally among the Triceratia. It probably
forms the type of a new genus.

BRIGHTWELL ON DIATOMACE. 181

13. Amphitetras crux, n. sp.—Valve cruciform, with the
extremities widely rounded, cellular punctate. (Pl. IX, fig.
13, a, front view; 4, side view.)

14, Amphitetras antediluviana (?) (Pl. IX, fig. 14.) —Mr.
T. West believes this to be a valve of a sporangial frustule,
of this species. Its unusuaily large size, imperfect shape
and thinness, the cellular appearance of its punctation, and
its occurrence among a large number of valves of the regular
form lead to this conclusion.

15. Biddulphia Balena.—V. ovate, elongated at the extre-
mities; F. V. quadrate. Frustule punctato-striate.

Zygoceros Balena, Ehr.—See Roper, on Biddulphia,
‘Trans. Micr. Soc.’ vol. vii, p. 20.

Arctic Regions, Cornwall Island, N. Lat. 75°, Dr. Suther-
Jand,

TRANSLATIONS.

FurtHer Oxsservations on the DrveLopmMent of PEntas-
TOMUM THNIOIDES. By Rup. Levucxarr.

(Henle and Pfeufer’s ‘ Zeitsch. f. rat. Medicin,’ 3 ser., Bd. iv, p. 78, 1858.)

Tue readers of this Journal will remember from my first
paper* that I had commenced a series of experiments, m
order to decide the question whether the Pentastomum den-
ticulatum, which occasionally occurs as a parasite im man,
be a fully developed animal, or whether, as might be con-
cluded from certain reasons, it merely represents the larval
condition of the well-known Pentastomum tenioides which is
found infesting the nasal cavity of dogs. To this end I had
infected three dogs with P. denticulatum, not more than a
few millimetres in size, by the introduction directly into
their nostrils of several dozen of these parasites, procured
from the abdomen of a rabbit.

The results of these experiments have been as yet only
partially made known. It has been stated that I detected
in one of those dogs, killed six weeks after infection (on the
17th February, 1857), three examples of a Pentastomum,
which, notwithstanding its insignificant size (8—10 mm.)
and incomplete development, could be recognised as Penta-
stomum tenioides. As I stated in a supplement to that com-
munication, a far more convincing result was obtained in a
second dog. In this case there were found (on the 20th of
June, about seventeen weeks after the commencement of the
experiment) not less than thirty-nine Pentastomata, of whose
agreement with the usual P. tenioides the smallest doubt
could not be entertained. About the half of these examples
were males; they were fully developed (15—16 mm. long),
and had also to a certain extent accomplished the copulative
function, as might be concluded from the circumstance of the
seminal pouches of some of the females being filled with
semen. The females were larger than the males (up to
26 mm.), though they had neither attained full growth, nor

* <Jahrg.,’ 1857, s. 48—60. “ Pentastomum denticulatum, der Jugend-
zustand yon Pent. tentoides.”

LEUCKART, ON PENTASTOMUM TENIOIDES. 183

arrived at sexual maturity. Their ovaries only just showed
the commencement of the formation of ova, and the vagina
(which at the same time serves as a uterus, and fills the
entire cavity of the body with its innumerable convolutions
in the fully developed female) was as yet not only empty, but
quite straight and of inconsiderable length (about 12 mm.)

The question has several times arisen as to the mode in
which the two spermatic pouches attached to the upper end
of the vagina can, in the fully formed Pentastomum, be filled
from without. In order to get over the difficulties of the
case, and to reconcile the fact with the enormous length and
impermeability of the vagina when filled with ova, it has
often been suggested that the statements respecting the sepa-
ration of the sexes in these parasites may be founded in error.
The foregoing observation affords the most complete ex-
planation respecting these conditions. It shows us that the
vagina of the female is still short and empty at the time of
copulation, and not longer than the two protrusile tubes
which represent, according to Van Beneden’s discovery,* the
truth of which is readily proved, the male copulative appa-
ratus, and which are variously twisted together and concealed
in a special muscular sac while in a state of rest. It is,
indeed, remarkable that the females are not sexually mature
at the time of copulation, but this peculiarity is not un-
frequent in the lower animals (which have spermatic recep-
tacles), especially among insects.

Of course it cannot at present be my intention to enlarge
in detail on the structure of the sexual organs of these animals,
—lI reserve this, as well as the explanation of the organiza-
tion of the Pentastomata, for a future opportunity,—but I
may perhaps be here permitted to say thus much, namely,
that the ovaries are situated on the dorsal, while the sexual
orifices are on the ventral surface, 7.¢., at the hinder part
of the body, close before the anal aperture in the females; in
the male the sexual orifices are placed (and this is the same
for both the cirrhus-pouches) much further forward, near the
oral opening.

The examination of the third dog, which was undertaken
on the 25th of August, 7.e., about six months after the
infection with P. denticulatum, gave the same positive
result as had been derived from the two preceding experi-
ments. The nasal cavity and the frontal sinuses also har-
boured a number of P. tenioides, and on this occasion
individuals of both kinds fully developed. In respect of

* ‘Recherches sur le developpement des Linguatules.’ Bruxelles, 1849,
p. 16.

184 LEUCKART, ON PENTASTOMUM TANIOIDES.

size and formation, the males, only two of which were found,
showed an entire agreement with the male Pentastomata
of the second dog; they had evidently gone through their
whole development two months before. But this was not
the case with the three females found with them, which
since that time had grown to more than double their
former length (up to 65 mm.), and had also arrived in the
mean time at complete sexual maturity. Not only were
their ovaries full of ova in various stages of development,
but the vagina, which measured nearly one millimetre, was
filled with them; and to such an extent was this the case,
that, according to a very moderate estimate, their number
could be calculated at fully half a million. As might be
expected, the ova in the vagina were all mature—nay, more,
they were even all fertilised, as might be concluded not only
from the circumstance that, before their entrance into the
vagina, they must pass the openings of the two seminal
pouches above mentioned, but especially from the considera-
tion that they already exhibited unmistakeable signs of a
commencing development of the embryo at a small distance
from the upper end of the vagina. ‘The lower fifth of the
vagina even contained ova with fully mature embryos.

The embryos of these Pentastomata were examined and
described several years ago, in Utrecht, by the late helmin-
thologist Schubart.* In all essential points they exhibit the
same structure which Van Beneden had previously found
in the embryos of Pentastomum proboscideum parasitic in
several species of snakes. They are so strikingly different
from the fully formed Pentastomata, that, in examining
them, we are reminded of certain Acarina and allied forms,
far rather than of the vermiform parasites now under consi-
deration.

The body of the embryo consists of two distinctly sepa-
rate parts—a short and broad, egg shaped anterior part
(0:07 mm. long, 0°05 mm. broad, and about the same in
height), and a rather long, slender tail (measuring 0°056 mm.
long and 0:010 broad), which, during its stay in the ovum, is
invariably folded on the ventral surface. On the contrary,
in the embryo of Pentastomum proboscideum—and I observe
the same in a second species discovered by Professor Harley
in London, from the lung of an African snake, the P. multi-
cinctum, Harl., the embryos of which also in other respects
agree almost entirely with those of P. proboscideum—the tail
is much shorter, and separated from the rest of the body in a

* ¢Zeits. fiir wissenschaft. Zool.,’ 1852, Band iv, s. 117.

LEUCKART, ON PENTASTOMUM TANIOIDES. 185

very marked manner, so that the similarity with a Mite above
referred to here shows itself still more conspicuously. The
anterior extremity of the body exhibits a tolerably large,
gaping oral aperture, whose lower margin especially is indi-
cated by a crescent-shaped eversion of the external chitinous
coverings, which are elsewhere generally very soft. Close
above this opening lies a boring apparatus, which is very
much stronger in the embryos of P. proboscideum and P.
multicinctum, and consists of a dagger-like aciculum, placed
in the middle and directed straight forwards, and two smaller
sete curved like a hook. The most characteristic feature of
this preabdomen consists in the presence of two pair of claw-
feet, which project laterally from the body and occupy nearly
the whole of the middle third.

Van Beneden and Schubart describe these feet as con-
sisting of two joints, and remark that the two claws form a
prehensile apparatus. I must dispute, however, the correct-
ness of these statements, and may do so the more decidedly,
as I have subjected this matter to a careful examination.

The embryonal pedal tubercle of P. tenioides forms a
simple, short, and conical process, which throughout its entire
breadth projects from the substance of the body, and exhi-
bits no distinct articulation ; it supports two curved claws at
its extremity, which are placed, not one behind the other,
but sede by side, and both are curved backwards at their tips.
The end of the tubercle supporting these claws is truncate,
and provided at the margin with a strong, hard, chitinous
ring. I scarcely doubt that the claws are possessed of inde-
pendent motion.

In addition to the above-mentioned chitinous ring, we
may distinguish other solid deposits of rod-shaped bodies in
the coverings of the pedal tubercles. In certain positions
these appear under the form of a two-pronged fork, the
prongs of which, diverging from the place of origin, run
downwards, and may be traced up to the extremity of the
tubercles. A nearer examination shows that in such an
aspect, the anterior surface of the pedal tubercles is always
that which is brought into view. I especially recommend
the profile aspect, in order fully to comprehend this forma-
tion, by the imvestigation of which one arrives at the con-
viction that only the two diverging prongs of these rods
belong, properly speaking, to the chitinous covering of the
foot, while the stem, which is a continuation from them, has
no other connexion with the chitinous covering, and projects
freely into the contractile parenchyma of the body. Evi-
dently this stem forms a lever, by means of which the motion

186 LEUCKART, ON PENTASTOMUM TZNIOIDES.

of the short and stump-like foot is rendered considerably
easier. ‘This description apples not only to the embryos of
Pentastomum tenioides, but also to those of P. proboscideum
and P. multicinctum ; nay, in the latter the structural con-
ditions of the foot are still more distinct, because the ap-
pendages in question, with their separate parts, are nearly
twice as large.

When former investigators regarded the legs of the em-
bryo of Pentastomum as made up of two successive segments,
they were probably deceived by the inclosed chitinous rods,
and, in particular, looked upon the peduncular process of
the foot-coverings as the anterior contour of a separate
segment. But although such a deception is quite possible
in certain positions, the true state of the case will soon be
ascertained when the parts are viewed in other and more de-
terminate directions.

Many zoologists appear to entertain the opinion that these
pedal tubercles of the Pentastomum-embryo gradually change
into the well-known claw-like appendages of the perfect
animal in the course of its development. To such an
assumption I was myself inclined at first, and the more so as
the chitinous fork of the pedal tubercles really bears some
resemblance to the subsequently developed organs of sup-
port; and the two embryonic claws might be readily com-
pared with the two hooks of P. denticulatum. I have, how-
ever, by later examinations, ascertained the incorrectness of
this hypothesis, and arrived at the conviction that the claw-
feet of the embryos, with all their separate parts, represent an
apparatus which vanishes entirely during the later metamor-
phoses. In a physiological point of view, however, one may
well compare these structures with the claw-apparatus of
the adult animal. The coronets of spines of Pentastomum
denticulatum are in a similar manner represented in the
embryos by some small and delicate sete, which are found
arranged symmetrically, but varying in number, at the pos-
terior extremity of the caudal appendage.

Besides the structures hitherto described, there also exists
a roundish sucker-like indentation in the centre of the
dorsal surface of the embryo, the bottom of which rises in
the shape of a cross. The embryos of P. proboscidewm and
P. multicinctum are likewise possessed of these dorsal depres-
sions, but here they are less considerable and without the
cross. Internal organs are not perceptible, nor can even any
intestine be discovered, although the oral aperture is of con-
siderable size. (I am uncertain whether there be an anus.)
The entire parenchyma of the body consists of a tolerably

LEUCKART, ON PENTASTOMUM TANIOIDES. 187

homogeneous granular material, in which, especially at the
lower part, are distributed numerous fat-like corpuscles.

The embryos here described are never found free in the
sexual passages, but always remain surrounded, even in the
lowest portions of the tract, by the coverings of the ovum,
which are three in number, as has been quite correctly stated
by Schubart and Van Beneden. The most exterior forms a
clear, transparent coat, with many folds in P. tenioides,
which is separated from the two internal tunics by a wide
intervening space; and it is possessed of a glutinous cha-
racter, by means of which the eggs adhere to foreign objects
with great facility, a circumstance which in a high degree
favours their dispersion and transplantation. In P. tenioides,
the substance of this exterior covering is converted by the
addition of caustic potass into a gelatinous material, which is
dissolved under the continued action of the reagent, while
the two interior envelopes, which are closely approximated
to one another, remain unaltered. These two latter have a
very delicate and brittle consistence, so as to be readily rup-
tured by the application of pressure. This is especially the
case with the middle covering, which is also distinguished
from the inner by its greater thickness and yellow colour.
Schubart says, in regard to the latter, that it is constantly
“provided with a little opening or facet.”” According to our
present knowledge of the mode of fertilization of animal ova,
we might perhaps interpret this statement to imply that the
ova of Pentastomum are provided with a micropyle; but the
apparent opening is in reality anything but a micropyle. An
investigation of the previous stages of development soon
shows that the entire innermost coat, together with the
structure under consideration, only makes its appearance a
long time after the fertilizing act, and in such a peculiar
manner, that it might perhaps with perfect justice be re-
garded as an embryonic membrane. Only the ova contained
in the last fourth of the vagina permit us to recognise the
three coats above described, while the others present only
two of them, which subsequently become the middle and
internal coverings. In the first or anterior part of the
vagina the coats are moreover only thin and extensible, and
lie closely upon one another, the exterior one also presenting
a different granular character. All these are circumstances
which render the process of fertilization intelligible even
without a micropyle.

The first signs of the commencing development of the
embryo consist in a segmentation of the yelk, which, how-
ever, at an early stage, generally immediately after the first

VOL. VII. Q

188 LEUCKART, ON PENTASTOMUM TENIOIDES.

division, becomes irregular and is on the whole not very
conspicuous, since the yelk-masses never separate from each
other into distinct globular forms. After the segmentation
is completed, the yelk resumes pretty much its former fine-
granular appearance, only that it is now become more trans-
parent. A distinctly cellular structure is scarcely to be
observed in this case, but no doubt, not so much because it
is wanting, as on account of the cells having only a very
small size and a tolerably homogeneous character.

While the yelk of the Pentastomum originally fills the
whole internal cavity of the oval egg, it subsequently con-
tracts after the segmentation 1s completed, so that an inter-
mediate space is formed between it and the contiguous coat.
(The character of these coats is now what it will be afterwards,
and the external is likewise already transparent and distant.)
At the same time the surface of the yelk exhibits a well-
defined, almost membranous border. In the middle of the
part which subsequently becomes the dorsal surface, there
appears a shallow saddle-shaped indentation. Where this
depression is deepest, the membranous surface of the yelk
thickens into a clear conical process, which projects, com-
paratively speaking, to a considerable depth into the sub-
stance of the granular yelk.

At this stage of development the ovum of the Penta-
stomum remains for a long time, as we may conclude at least
from the circumstance that more than two fifths of the
vagina are filled with ova in this stage. (In P. oxycephalum,
from the lung of the Kaiman, investigated by myself, the de-
velopment of the ova does not appear to make any further pro-
gress in the vagina of the parent; at least, no later stages of
growth could be observed in a dozen of these animals.) At
the commencement of the last third of the vagina, the dorsal
process just described assumes an hour-glass form; it is
divided by a circular groove into an upper and lower half,
the former of which, with its margins, passes directly over
into the limiting surface of the yelk, which in the mean time
is becoming more and more distinctly membranous. At the
same time may be observed opposite the dorsal process, in
the middle of the part that afterwards becomes the ventral
surface, a transverse groove, by which it is divided into an
anterior and posterior zone. The membranous boundary of
the yelk-mass does not take part in the formation of this
groove, on the contrary it extends across it like an arch, so
that in the place in question a little intervening space is
formed between. the yelk-mass and the previously closely

LEUCKART, ON PENTASTOMUM TANIOIDES. 189

applied membrane. ‘This groove, however, only remains for
a short time in its primitive form; it very soon deepens
into a cleft, which penetrates into the yelk-mass towards the
posterior pole in a diagonal direction. The yelk-segment
which is separated by this notch, and coheres with the re-
maining yelk, only on the dorsal surface of the egg, is the
first indication of the tail, of which we have already stated
above, that it is constantly folded upon itself forwards under-
neath the abdomen whilst the embryo remains within the
egg-coverings.

After the yelk has thus in general assumed the morpho-
logical conditions of the future embryonic body, it likewise
commences to retreat at other points from the membranous
layer with which it is coated, and to clothe itself, with a new
cuticular covering, the future chitinous shield. The former
vitelline membrane in this manner becomes a capsular
covering of the embryo, in the same way as the two primi-
tive egg-envelopes formed a long time previous; it becomes
the innermost coat of the ovum. It is true that, on the
dorsal process, this envelope is for a time connected with the
embryonic body inclosed within. But this connexion is like-
wise gradually dissolved, from the circumstance, that the
grooving in the centre of the dorsal process above mentioned,
deepens more and more, and finally separates the structure in
question into two isolated parts. The upper part remains
seated on the internal coat of the ovum, forming the “ facet”
seen by Schubart, while the lower portion becomes the dorsal
depression of the embryo, the margins having in the mean-
while become continuous with its chitinous covering. After
the separation an alteration often takes place in the relative
position of the embryonic body and the internal egg-shell,
and on this account, as Schubart has also remarked, we
often find the facet placed laterally or even on the ventral
surface of the embryo.

Even before the separation of the future dorsal depression
is completed from the facet of the interior embryonic cover-
ing, the pedal tubercles, with their claws, have also made
their appearance. They arise at a time in which the rudi-
ment of the tail has but just been formed and the dermis still
appears extremely thin, and in the form of two elevations at
the sides of the anterior body. The claws are formed earlier
than the chitinous ridges, and in respect of the latter again
the prongs of the fork earlier than the stem. At the same
time there arises along with the claws, at the anterior extre-
mity of the embryonic body, a roundish depression, consti-

190 LEUCKART, ON PENTASTOMUM TAENIOIDES.

tuting the mouth, the chitmous margin of which, however,
does not thicken till a later period, when the organs of
support become visible on the legs.

Of late it has been the fashion to regard the Pentasto-
mata as belongmg to the Acarina or Crustacea. But
the above observations respecting their embryonic develop-
ment would scarcely be in favour of this hypothesis, and
might perhaps be adduced against it. It has hitherto been
considered a general law, that the Arthropoda, to which the
Acari and Crustacea belong, are developed by means of a
primitive streak, while the Pentastomata present us with
the mstance of a universal development, such as is usually
observed in the Annelida. That the formation of the embry-
onal legs is also by no means to such an extent mite-like or
crustacean, as was formerly assumed when an articulation
was assigned to them, has been demonstrated above in detail.
According to the present state of our knowledge respecting
the Pentastomata, it would scarcely be at once considered
erroneous and unnatural, if some one undertook to defend
the old view of the worm-nature of these animals. Although
a further and more exact imvestigation of these relations
would be here inappropriate, I have referred to them because
many modern helminthologists, well known to the medical
public, have probably set too much weight on the presumed
crustacean and acarime character of these parasites. Again,
on the other hand, notwithstanding the doubts I have here
expressed, we must not forget, that im various respects (such
as the general form of the embryo, the formation of the
chitinous covering, and transverse striation of the muscles,
&e.) the Pentastomata do really exhibit a greater approxima-
tion to the higher articulated animals, than we are elsewhere
accustomed to see in a worm.

After these remarks let us return to our proper subject,
z.é., to the life-history of the Pentastomata.

The three dogs into which I had introduced the Pentastomum
denticulatum were thus, on examination, without exception
found to be infested with P. tenioides, and some of them
even with very numerous individuals of that rare parasite.
It was also apparent that the various states of development of
these animals corresponded accurately with the differences
and duration of the experiments—that is to say, their deve-
lopment was always the more complete, the longer the
interval since the period of introduction.

From these results we are fully justified in concluding that
the Pentastomata found in the infected-dogs were descended-
from the introduced P. denticulatum. In other words, that

LEUCKART, ON PENTASTOMUM TANIOIDES. 191

that species represents the young condition of Pentastomum
tenioides.

With the establishment of this fact, our knowledge of the
life-history of the parasites in question has certainly been con-
siderably advanced, though by no means brought to a con-
clusion. Before we can boast of this, the question of the
developmental history of Pent. denticulatum must be first
fully solved.

The embryos of P. tenioides exhibited structural condi-
tions which are remarkably different from those of Pent.
denticulatum, but in what manner and under what conditions
these differences are equalised, is as yet completely unknown.

In my first communication respecting Pentastomum den-
ticulatum, I have suggested that, aceording to older observa-
tions incidentally made, the ova of P. tenioides, which are
ejected with the nasal mucus, might be accidentally in-
troduced into the food of rabbits, and then swallowed by
these animals. It was further assumed that the egg-shells
are dissolved in the cavity of the stomach by the influence
of the gastric juice; that the embryos being set free, pierce
the intestinal walls, enter the various organs, and are there
developed, under favorable circumstances, into the well-
known form of P. denticulatum. This hypothesis was partly
founded on the organization of the embryo and the cha-
racter of its egg-coverings, partly also upon the analogy
with other helminths, especially the Tzeniz, whose eggs and
embryos exhibit similar relations. Besides this, I had on a
previous occasion tried in vain to make the embryos of these
animals escape from the egg by keeping them for some time
in water.

The correctness of this hypothesis had now to be tested
experimentally. For this purpose, on the very first day of
the last investigation (August 25th), I fed eight rabbits with
ova containing mature embryos taken from my three female
Pentastomata.

Two of these rabbits were destroyed within the next few
days. I had hoped to surprise the young embryos in the act
of migrating in the interior of their host, but my experiments
in this direction unfortunately failed; partly, perhaps, be-
cause, being still uncertain of a favorable result, I did not
devote myself with that perseverance which is necessary in
such delicate matters. Nevertheless, I scarcely doubt that a
repetition of these researches will repay the trouble, for the
discovery of the embryonic Pentastomata is certainly less dif-
ficult than that of the six-hooked embryos of the tape-worm,
which are much smaller. The differences of size between
the two kinds of embryo are so marked that they perhaps

192 LEUCKART, ON PENTASTOMUM TZAENIOIDES.

influence the direction which the wanderers select in the
body. This much at least is certain, that if the embryos of
the Pentastomata follow the circulation of the blood, like
those of the Tzenioid worms, it can only be when they obtain
access to the larger vessels.

[Here follows in the original the detailed account of several
observations on the earliest condition of the larval Pentusto-
mum, which it seems hardly necessary to give at length; and
we shall therefore conclude with the author’s summary of
the results of his experiments and researches.

These, he says, may be comprehended under some such
laws as the following:

1. That the entozoon known under the name of Penta-
stomum tenioides from the nasal cavity of the dog and wolf,
passes the early stage of its existence in the interior of the
rabbit and other mammals, especially in the lungs and liver
(occasionally also in man).

2. The development of Pentastomum tenioides takes place
under a simple metamorphosis, and presents four successive
phases :

(a) The condition of the Pentastomum-embryo, furnished
with a boring apparatus and claw-feet.

(2) The condition of the encysted and immotile Pentasto-
mum (the pupa state).

(c) The condition of the so-termed Pentastomum denticu-
latum, with a crown of spines and double hooks, one of which
is moveable (the larval condition).

(d) The condition of the sexually mature Pentastomum
tenioides, with simple moveable hooks and without a crown
of spines.

3. The time occupied in the development of Pentastomum
tenioides is nearly a year—the larger portion of the period
being taken up in the formation of the larval form (Pent.
denticulatum), and the remainder devoted to the trans-
formation into the sexually mature animal (P, tenioides).
The male reaches maturity earlier than the female.

4, The embryo and larva, possessing special provisional
motile organs, are organized for an active migration; and
consequently are in a condition either to change their posi-
tion in the interior of their host, or to pass from one host to
another.

5. The first migration of these parasites is passive, mas-
much as the ova containing mature embryos issued into the
outer world contaminate the food of other animals in com-
pany with which they are conveyed into the stomach,

LEUCKART, ON PENTASTOMUM TANIOIDES. 193

The observations contained in the foregoing paper, and the
conclusions summed up im the five propositions just stated,
immediately apply, it should be observed, only to the Pen-
tastomum tenioides of the dog; although in all essential points
they might be equally applied to the other species of Pen-
tastomum as well. This the author believes he will be able
to show in a further series of experiments.

In the course of the last year he had an opportunity, besides
P. tenioides, of examining a large number of other Penta-
stomata, some in a condition of ‘sexual maturity and some
in an immature state. Of the former, he notices P. pro-
boscideum from the lungs of Lachesis and Boa constrictor ;
P. multicinctum, Harl., from the lungs of the Cobra di Ma-
rocco; and P. oxycephalum from the lungs of the Cayman.
All these forms agree with each other and with Pent.
tenioides in the circumstance that they are without the crown
of spines and accessory hooks; and further, that they live
free in the interior of certain organs filled with air.

The sexually undeveloped Pentastomata examined by him,
on the other hand, presented, without exception, accessory
hooks and a crown of spines, although they exhibited con-
siderable diversities in size and form, more especially in the
latter. These forms, therefore, associate themselves with P.
denticulatum. This analogy is the more important, since
one of these undeveloped forms in all probability belongs to
the P. oxycephalum noticed above, which, in the fully deve-
loped condition, possesses none of the organs in question.

From these observations, it seems to the author not too
bold to conclude that the second species of Pentastomum
(P. constrictum, V. Sieb.), found by Pruner and Bilharz, in
Egypt, in man, may also represent an immature young form.
He is inclined to adopt this opinion, not only because the
form in question occurs encysted in the liver, but more espe-
cially because Bilharz (‘ Zeitsch. f. wissen. Zoolog.,’ Bd. iv,
p- 68) says respecting it, that the hooks corresponded with
those of P. denticulatum, and consequently were furnished
with accessory hooklets. It is true that V. Siebold (op. cit.,
vil, p. 831) expressly states a particular, hardly reconcileable
with this view, viz., the absence of the circlet of spines; but
this perhaps merely proves that the apparatus is exceedingly
minute, and discoverable only by microscopic examination.
The presence also of the sexual organs in the encysted Pen-
tastomata, which has been adduced by some (Van Beneden)
as a proof of their independence and perfect development,
ean now of itself be regarded as proving nothing, since the
author’s researches have established the fact that these organs,
with all their essential parts, are present during the pupa state. |

194,

REVIEWS.

Das Mikroskop ; Theorie, Gebrauch, Geschichte, und gegen-
wartige Zustand desselben. |The Microscope; its theory,
use, history, and present state.| By Prof. P. Harrine.

(Translated from the Dutch in German, by Dr. F. W. Tu1Ez.)

Proressor Hartine’s work on the ‘ Microscope,’ origi-
nally written in the Dutch language, and consequently a
sealed book to all but a very few, appeared in three distinct
portions or volumes, to which a voluminous appendix was
added last year. The whole was thus brought up to the
present time.

These volumes and the appendix are now brought together,
and constitute a goodly tome of nearly 1000 pages, illus-
trated with about half as many excellent woodcuts, illustrating
almost every subject connected with the microscope and its
adjuncts.

The present edition, moreover, has been excellently trans-
lated, under the author’s immediate supervision, by a very
competent microscopist, into a language which will render it
generally available, and it may therefore be almost regarded
in the light of an original work.

It is, undoubtedly, the most complete and _ satisfactory
treatise on the microscope that has yet appeared, containing,
in fact, a compendium of all that can be said, or nearly so,
on that instrument and its use, and nothing more. For,
notwithstanding its considerable size, the book contains very
little matter not having immediate reference in some way to
the instrument itself or its use. The only exceptions to this
are the descriptions and figures of crystals, &c., belonging to
the department of micro-chemistry. It does not include, as
do most other works on the microscope, copious observations
and representations of all kinds of so-termed microscopic
objects, which, though interesting and useful in themselves,
are scarcely properly placed in the pages of a work pro-
fessedly upon the instrument by which they are viewed.

Professor Harting’s treatise is divided into three parts or
books, of which the first relates to the theory and general
description of the microscope, including of course its optical

HALF-HOURS WITH THE MICROSCOPE. 195

arrangements. In the second book, the use of the micro-
scope is described, and copious details given respecting the
making of microscopical preparations; whilst in the third,
we have a lengthened historical account of the instrument in
all its forms, and of the state of comparative perfection at
which it has now arrived. Every kind of accessory appa-
ratus is also here described, and the utmost pains appear to
have been taken to render this part of the work complete,
and so far as we can perceive with success.

The subjects of micro-chemical analysis, micrometry,
microgoniometry, &c., the estimation of the absolute and
specific weights of microscopic objects, their refractive and
polarizing properties, &c., are fully and ably treated.

Microscopic drawing and micro-photography also find a
place.

In fact, nothing seems to have been omitted to render the
present one of the most complete and useful works yet pub-
lished on the subject of the microscope—and as such we
recommend it to our readers.

Half-hours with the Microscope ; being a popular guide to the
use of the microscope as a means of amusement and
instruction. Illustrated from Nature, by Turren West.
Pp. 83.

Tus unpretending little book is really one of considerable
worth, and will be found interesting to a large class of
Incipient microscopic observers, who use their instrument
more for the purposes of rational amusement than with any
actual scientific object. Its great value depends upon the
plates, which are filled to repletion with accurate and well-
drawn figures of a vast number of objects culled with much
discrimination, from almost every department of natural
history. To say that the figures have been executed by
Tuffen West is to say that they are good and faithful
representations of what they profess to delineate—and as we
presume the objects were themselves selected by that gentle-
man, his judgment appears to have been as well exerted in
that selection as his skill in the representation of the things
selected.

The text is succinct and clear, giving in as few words as
possible a description of the various objects represented in

196 WEST, ON THE MICROSCOPE.

the figures, preceded by some brief and judicious remarks as
to the mode of using and nature of the instrument.

We give an extract as an illustration of the style in which
this little volume is written :

“There is considerable difficulty in at once distinguishing between the
lowest forms of animals and plants. Although the animal generally pos-
sesses a mouth, and a stomach in which to digest its vegetable food, there
are some forms of animal life so simple as not to possess either of these
organs. In the sediment from ponds and rivers there will frequently be
found small irregular masses of living, moving matter. If these are
watched, they will be found to move about and change their form constantly.
As they press themselves slowly along, small portions of vegetable matter,
or occasionally a diatom, mix apparently with their substance, Cells are

roduced in their interior, which bud off from the parent, and lead the same
ife. These creatures are called amebas; and though they have no mouth
or stomach, they are referred to the animal kingdom. They appear to be
masses of protein (sarcode) without any cell-wall. If we suppose an ameba
to assume the form of a disc, and to send forth tentacles, or minute elon-
gated processes from all sides, we should have the sun animalcule (Aetino-
phrys Sol). This curious creature bas the power, apparently, of suddenly
contracting its tentacles, and leaping about in the water. It can also con-
tract its tentacles over particles of starch and animalcules, and press them
into the fleshy substance in its centre. ‘This is undoubtedly an animal, but
it has no mouth or stomach. A large number of such forms present them-
selves under the microscope. Some of them are covered with an external
envelope, which they make artificially, by attaching small stones and other
substances to their external surface, as in the case of the Diflugia ; or they
may form a regular case, or carapace, of cellulose, as is seen in Arcella. We
shall meet again with forms resembling these when we take our microscope
to the sea-side,

“One of the most common animalcules met with in fresh water, and
whose presence can easily be ensured by steeping a few stalks of hay in a
glass of water, is the bell-shaped animalcule. These animalcules, which are
called Vorticella, are of various sizes. Some are so large that their presence
can easily be detected by the naked eye, whilst others require the highest
powers of the microseope. ‘They are all distinguished by having a little
cup-shaped body, which is placed upon a long stalk. The stalk has the
peculiar power of contracting in a spiral manner, which the creature does
when anything disturbs it in the slightest manner. In some species these
stalks are branched, so that hundreds of these creatures are found on a
single stem, forming an exceedingly beautiful object with the microscope.
The stalks of these compound Vorticelle are contracted together, so that
a large mass, expanding over the whole field of the microseope, suddenly
disappears, and, ‘like the baseless fabric of a vision leaves not a wreck
behind. A little patience, however, and the fearful ereatures will onee
more be seen to expand themselves in all their beauty. The mouth of
their little cup is surrounded by cilia, which are ia constant movement ;
and when examined minutely, they will be found to possess two apertures,
through one of which currents of water pass into the body, and from the
other pass out. Not unfrequently the cup breaks off its stalk. Jt then
contracts its mouth, and proceeds to roll about free in the water. Many
other curious changes in form and condition have been observed in these
wonderful bell-shaped animalcules.”

There is also an Appendix, on the Preparation and Mounting

WEST, ON THE MICROSCOPE. 197

of Objects, by Mr. Thomas Ketteringham, which will be
found very useful to beginners. he following is the intro-
ductory passage to this portion of the work :

“The majority of objects exhibited by the microscope require some kind
of preparation before they can be satisfactorily shown, or their form and
structure properly made out. To convince tlie beginner of this, let him
take the leg of any insect, and, without previous preparation, place it under
his Microscope, and what does he see? A dark opaque body, fringed with
hair, and exceedingly indistinct. But let him view the same object pre-
pared and permanently mounted, and he will now regard it with delight.
That beautiful limb, rendered transparent by the process it has undergone,
now lies before him, rich in colour, wonderful in the delicate articulation of
its joints, exquisite in its finish, armed at its extremities with two sharp
claws equally serviceable for progression or aggression, and furnished, in
many instances, with pads (pz/vill/), which enable the insect to walk with
ease and safety on the smoothest surface. If the beginner has a true love
for the study of the microscope, he will be glad of information respecting
the method pursued in dissecting and preserving microscopic objects, nor
will he rest satisfied until he has acquired some knowledge of the art. We
will briefly point out a few of the advantages possessed by those who are
able to prepare specimens for themselves.

‘Objects well mounted will remain uninjured for years, and will con-
tinue to retain their colour and structure in all their original freshness.

“They can be exhibited at all times to one’s friends, and may be studied
with advantage whenever an opportunity occurs.

‘By the practice of dissection such a knowledge is gained of the varied
forms and internal organization of minute creatures as can be obtained in no
other way.

“There are doubtless many who, possessing a small microscope, are
unable by reason of their limited means to expend money in the purchase of
ready-prepared specimens. ‘To such a few plain directions, if followed, will
be of service, and will enable them to prepare their own.

“The materials necessary for the beginner are few, and not expensive.
Tn fact, the fewer the better; for a multiplicity is apt only to cause con-
fusion. The following will be found sufficient for all ordinary purposes, and
may be obtained at any optician’s :

“ Bottle of new Canada balsam.

“ Bottle of gold size.

“Bottle of Brunswick black.

Spirits of turpentine—small quantity.

* Spirits of wine—small quantity.

‘Solution of caustic potash (diguor potasse).

* Ether—a small bottle.

“Empty pomatum-pots, with covers, for holding objects while in pickle.

“ Half a dozen needles mounted in handles of camel-hair brushes.

“Pair of brass forceps.

«Two small scalpels.

“ Pair of fine-pointed scissors.

«* Camel-hair pencils—half a dozen.

“Slips of plate-glass, one inch by three inches—two dozen.

“Thin glass covers, cut into squares and circles—half an ounce.

“We will suppose that the beginner, having purchased the necessary
materials, is about to make his first attempt. Let him attend to the fol-
lowing advice, and he will escape many failures.

“He must bring to his work a mind cool and collected; hands clean and

193 WEST, ON THE MICROSCOPE.

free from grease. Let him place everything he may require close at hand,
or within his reach. A stock of clean slides and covers must always be
ready for use. He must keep his needles, scissors, and scalpels serupu-
lously clean. An ingenious youth will readily construct for himself a box
to contain all his tools. Cleanliness is so essential to success, that too
much stress cannot be laid upon it. All fluids should be filtered and kept
in well-corked phials. A bell-glass, which may be purchased for a few
pence, will be found exceedingly useful in covering an object when any
delay takes place in the mounting. For want. of it many specimens have
been spoilt by the intrusion of particles of dust, soot, and other foreign
substances. Let the table on which the operator is at work be steady, and
placed in a good light, and, if possible, in a room free from intrusion.”

From these extracts and the known excellence of Mr.
West as a delineator of microscopic objects, our readers will
be able to form a judgment of the merits of this little
introduction to the use of the microscope.

199

NOTES AND CORRESPONDENCE.

Mr. Warington’s Portable Aquarium Microscope.—There is,
perhaps, no department of microscopic investigation so inter-
esting to most observers as the development, growth, and
habits of vital organisms. The aquarium has now become
popular, and thrives in the homes of many who do not pre-
tend to cultivate science; but how often do we find that it
is unaccompanied with any adjunct for assisting the eye to
scrutinise the form and structure of its living tenants. Much
of the interest and mental recreation which a study of the
details of these remarkable beings will afford is lost, for
want of that indispensable appendage, a simple form of
microscope easy of application. To the ingenuity of Mr.
Warington we are indebted for an instrument (described in the
present ‘ Journal’) which meets all the requirements of the
case, being cheap, simple, and not lable to get out of order.

By reason of the position and other conditions under
which the objects to be observed are situated, there will
oftentimes be much difficulty in throwing light upon them,
particularly when object-glasses of the shortest practicable
focus are employed; for most frequently they require to be
viewed as opaque objects. I therefore offer some suggestions,
which I trust may lead to others of greater value.

If the aquarium, glass tank, or live-box, with its fluid
contents, be considered as a square prism, it will be seen that
aray of light incident upon any one of its four plane sur-
faces, may be thrown back again from the adjoining plane in
various directions, within the angle of total reflection. We
may sometimes avail ourselves of this fact for the illumination
of an object in a peculiar position. Leta aa represent the
glass sides of an aquarium, 6 the surface of the water. The
object to be viewed at c, with the object-glass (d). If the
rays from a lamp be thrown in the direction shown, by means
of the condensing-lens (e), after passing through the first
surface they will be refracted more towards the perpendicular,
and on reaching the glass wall of the tank will be reflected
back again on the object at c. It may be mentioned that
the total reflection of the rays takes place from the outer
surface of the plate glass; therefore, if a small specimen is
situated in close contact with the imner surface, it may be
found that there is ample space in the thickness. of the plate

200 MEMORANDA.

for light to pass over the object and be reflected back again
to the point of adhesion with the glass. If the aquarium
has glass sides the same rule will apply, which the diagram
will illustrate, by considering the tank, condensing lens, &c.,
to be in plan and placed at the side instead of the top.

|

e. is not a lens as shown, but a short thick line representing the place
of the object.
Of course, at a proper incidence, total internal reflection will
also take place from the top surface of the water alone, but
I do not see how this can be made available.

Object-glasses of a focus as short as half an inch may be
used in the aquarium by the following method: <A tube is
to be made to slide over the front of the object-glass, and
extending back for two or three inches over the body of the
microscope. A very small glass prism, either right angled or
equilateral, is cemented or otherwise fixed water-tight in
the end of the tube, with one of its faces nearly in contact
with the front lens. The microscope may be immersed in
the water, and used either vertically or inclined, as deep as
the “ water-boot” will allow. The diagram will explain the
arrangement. If the work is neatly put together, consider-
able focal distance may be obtained in front of the prism,
as for a half-inch object-glass it need not be more than
one eighth of an inch square, on its faces. The water
must not be allowed to get to the back of the prism, as
it will prevent total reflection therefrom, except at very
oblique incidences. For a direct forward view under water,
the prism may be replaced by a small disc of thin glass at
right angles to the ae axis ; this is an old suggestion br
Dr. Goring. —F. H. Wennam.

MEMORANDA. 201

Substitute for the Rack-and-Pinion movement of Microscopes.—
I have found the following application of the “ frictional
gearing” (sometimes used in cotton-spimning machinery)
answer perfectly well in lieu of the ordimary rack-and-pinion
movement of the body and stage of microscopes. It is quite
free from the unpleasant drop consequent upon a worn rack
and pinion, and is exceedingly strong, it beg impossible to
injure or fracture the movement, by any undue violence, in
turning the milled head, for beyond a certain amount of strain
it will slip.

Fig. 1 is a plan and fig. 2 side view of a microscope body
with this movement attached. The same letters of reference
apply to both figures ; a is the body of an ordinary microscope;
6 a strip of brass in the position of the usual rack—this is
planed out longitudinally into three or four angular furrows,
slightly truncated, as shown; c is a turned cylinder of steel
with milled heads, in place of the pinion—this has furrows and

Fig. 1. Fig. 2.

grooves of the same angle exactly corresponding with those of
the strip.

The pinion or roller is pressed into the strip by means of
a hammered brass spring (d), which serves to ensure a uniform
pressure, needful to obtain sufficient bite between the roller
and strip, to overcome the resistance of the work, and also
gives accommodation to any irregularities of construction.

The lifting power or bite depends upon the acuteness of the
angle given to the ridges and furrows, which must not be too
obtuse, or not exceeding 30°.

I have made a friction rack of this description which works
very smoothly, and lifts a weight of 16 lbs. without slipping ;
this force is amply sufficient for most optical purposes.—F.
H. Wenuam. .

202 MEMORANDA.

Notes on Tricuspidaria and Pentastoma.—In the preceding
number of this ‘ Journal’ (p. 115), a series of clearly defined
vascular prolongations are describea by me in connexion with
the calcareous corpuscles of Tricus,.daria. These tubular
extensions of membrane, though not previously recorded by
any observer, I have there represented to have been known
to Professor Van Beneden—an error unintentionally caused
by the omission of the monosyllable “no” in my MS. It
should have run thus: “In Professor Van Beneden’s ‘ Vers
Cestoides’ no mention is made of these tubular extensions in
the detailed and accurate description of this Cestode there

iven.’

. Since the memorandum referred to was published, I have
received Van Beneden’s great prize essay, entitled ‘ Mémoire
sur les Vers Intestinaux ; but the structure of the species
in question is not there treated at any further length.

As amore fitting opportunity could not occur, I will also
mention a peculiarity in respect of the hooks of Tricuspidaria
which has hkewise escaped notice. I allude to the presence
of thin chitinous lamin connecting the two lateral horns of
each hook to the central apophysis. The object of this ar-
rangement is probably to afford additional security to the
prong-like processes, thereby rendermg them capable of

One of the four cephalic hooks of Z'ricuspidaria nodulosa. x 280 diam.

greater resistance; but whatever other signification or use
they may possess, their general aspect inevitably reminds one
of the aortic semilunar valves in the human subject. Van
Beneden appears to think it an error that the cusps of the
hooks should have been figured in the ‘Régne Animal’ as
directed forwards, and has himself, consequently, drawn the
hooks with the points downwards (‘ Vers Cestoides,’ pl. xxii).
On referring to the edition of Cuvier’s work, edited by his
pupils, I find Blanchard’s figure (‘Intestinaux,’ pl. xxxix)
to indicate an arrangement of the hooks precisely such as I
have myself seen and figured more than once with the aid of
a camera; in these cases the cusps were directed forwards.
It can scarcely be doubted, therefore, that under different
circumstances the same animal may display the hooks in
either direction, most probably by inverting and everting

MEMORANDA. 203

the head, the performance of this function having perhaps
escaped observation.

In regard to Pentastoma, I am greatly indebted to Professor
Busk for having placed in my hands a memoir on the develop-
ment of this genus by Professor R. Leuckart,* the perusal of
which has induced me to commence a repetition of that dis-
tinguished entozoologist’s experiments. The Council of the
Zoological Society having liberally accorded me an oppor-
tunity of examining the carcases of certain animals dying at
the Society’s Gardens, Regent’s Park, the evisceration of a
Bubale (Antilope Budalis, Pallas), on the 10th ultimo
(February), fortunately supplied me with fourteen individuals
of the so-called Pentastomum denticulatum. Nine of these
entozoa were the next day introduced into the nostril of a
hound ten months old, and four mto the nasal cavity of an older
dog—the other solitary parasite being retained for careful
microscopic examination.

On the 4th of the present month (March), 7.e., three
weeks after infection, the first hound was destroyed, but the
most rigid inspection of the entire nasal, frontal, and facial
cavities failed to detect a single specimen of our young
Pentastomata. The second dog has not yet been killed.

I have thought it right to: place on record this first,
although a negative, result. Those only who comprehend
the saving value, in respect of checking the superabundance
of these and other allied parasites, by obtainmg an accurate
knowledge of their early wanderings and transformations,
will understand the reasonableness of continuing these
helminthological inquiries, in spite of the seeming destruc-
tion of life which they at present involve-—T. Spencer
Cosson, London.

* See Translation, in another part of the present number of this
‘ Journal.’

VOL. VII. R

204,

PROCEEDINGS OF SOCIETIES.

MicroscoricaL Society, December 22d, 1858.
Dr. LanxesteER, President, in the chair.

A paper by Lieut. Mitchell, of Madras, “ On anew form
of Circulating Apparatus observed in a species of Nepadee”’
(‘ Trans.,’ p. 36), and also one by Dr. F. Cohn, “ On Nassula
elegans,” were read (‘ Journal,’ p. 96).

January 26th, 1859.
Dr. Lanxester, President, in the chair.

J. H. Stewart, Esq., Royal College of Surgeons, and J.
Pullman, Esq., 17, Greek Street, Soho, were balloted for, and
duly elected members of the Society.

The following papers were read :

1. “On Parasitic Fungi of the Human Skin,” by Jabez
Hogg, Esq. (‘Trans.,’ p. 39).

2. “Ona new Instrument for observing Diatomacere,” by
J. N. Tomkins, Esq. (‘Trans.,’ p. 57).

Mr. Warington described certain improvements in his
Portable Microscope (‘ Trans.,’ p. 58).

February 16th, 1859,
ANNUAL GENERAL MEETING.

Dr. LanxesteErR, President, in the chair.

Reports from the Council, on the progress and present
state of the Society, and from the Auditors of the Treasurer’s
account, were read.

The President delivered an address, giving an account of
the proceedings of the Society and of the*progress of micro-
scopical science during the past year.

Resolved that the Reports now read be received and
adopted, and that they be printed and circulated in the usual
manner, with the President’s address.

PROCEEDINGS OF SOCIETIES. 205

The following donations have been made to the Society :

December 22d, 1858. Presented by
Journal of Royal Dublin Society . The Society.
On the Arrangement of Cutaneous Muscles of the Larva
of Pygera : . J. Lubbock, Esq.
Journal of Society of Arts, Nos, 814323 . The Society.
Journal of Photographic Society,.3 Nos. .
Pritchard’s Animalcules ; . J. Hogg, Esq.
Bailey on Infusoria : A 3 . Ditto.
Bailey on Navicula Spencerii : E . Ditto.
Bailey on a New Animalcule : ; . Ditto.
Bailey on Deep-sea Soundings .. j . Ditto.
Rainey on Shells ; F : . The Author.
January 26th, 1859.
Dr. Guy on Crystals of Arsenious Acid 5 : Dr! Guy:
Adams on the Microscope : . Mr. Williams.
Brewster’s Treatise on the Microscope : . A. Brady, Esq.
February 16th.
Half Hours with the Microscope . . Mr. Hardwick.

The Canadian Journal of Industry, Science, and Art . The Editor.
Zur Kenntuiss des Generationswechsels und der Par-

thenogenesis s . Dr. Harley.
Beale on tie Microscope i in Medicine . Dr. Beale.
Beale on Urine, Urinary Deposits, and Caleuli . Ditto.
How to Work with the Microscope - Ditto.
Hight Microscopic Slides of Shell Development . . Mr. Rainey.

Hutt MicroscoricaL Sociey.

Tue members of the Hull Microscopical Society gave an
evening dress soirée to about one hundred and fifty ladies
and gentlemen, in the Philosophical Rooms and Museum of
the Royal Institution.

A brief opening address was delivered in the lecture hall,
by Mr. Sollitt, at eight o’clock, explanatory of the great im-
provements which had of late years been made in the micro-
scope, through the discoveries and researches of the members
of the Hull Microscopical Society. He referred also to the
great advantages which had been realised by the making of
object-glasses of a large angle of aperture, which increase of
angle was in a great measure owing to the importance
attached by the Hull microscopists to viewing the lines of
Diatomacee. He also spoke of the indisputable pre-emi-
nence of the microscope in the detection of adulteration of
food.

206 PROCEEDINGS OF SOCIETIES.

After Mr. Sollitt’s address the company adjourned to the
side room, where tea and coffee and refreshments were amply
provided.

The company then assembled in the museum, where, at
different tables, the following class of objects was exhibited
by the members of the Microscopical Society, each micro-
scope being accompanied with a card containmg the names
of the objects exhibited: 1, Spicula and Gemmules of various
Sponges, J. D. Sollitt; 2, Sections of Spmes from the Echi-
nodermata (Sea Urchins), J. D. Sollitt; 8, Vegetable Struc-
tures, Sir Henry Cooper; 4, Sections of Agates, &c., viewed
by Polarized Light, B. Jacobs; 5, Vascular Structures of
Animal Bodies, J. H. Gibson ; 6, Micro-Photographs, Hy.
Munroe; 7, Crystallized Salts, viewed by Polarized Light,
Hy. Munroe; 8, Anatomical Preparations (Human), Hy.
Munroe; 9, Shells of Diatomaceze, Foraminifera, Polycis-
tine, Dr. Bell; 10, Dissections of Insects, R. Harrison;
11, Ciliary Movement in the Mussel—Circulation in Plants
(Valisneria spiralis), R. Harrison; 12, A variety of Acari
(Mites), F. W. Casson; 138, Preparations of Marine Algz
(Sea Weeds), W. Parker; 14, Parasites of various Animals,
W. Parker; 15, Scales from the Wings of Butterflies, Moths,
&e., Dr. Lunn; 16, Injected Physiological Preparations, Dr.
Daly ; 17, Sections of Teeth, S. Moseley; 18, Micro-Photo-
graphs, J. Malam.

At nine o’clock the company again assembled in the lec-
ture hall, when Mr. Munroe, surgeon, gave a short lecture
on the ‘ Revelations of the Microscope.” The screen was
filled with a great number of large and beautifully executed
diagrams illustrative of Acari, Diatomacez, blood-dises,
Desmidie, &c. Mr. Munroe gave a short description of
each diagram, and referred the audience to the original
slides, which were shown in the museum by the different
members of the Society.— Hull Paper.

207

ORIGINAL COMMUNICATIONS.

On PLacioGRAMMA, @ NEW Genus of DiaTomacrEa.
By R. K. Grevitxiz, LL.D., F.R.S.E., &e.

Tur only known species of the new genus of Diatomacez,
which I propose to establish in this communication, was
published by my late friend, Professor Gregory, in 1857, in
his paper “On the Marine Diatomacez of the Clyde”’ (‘ Trans.
Roy. Soe. Ed.,’ vol. xxi), under the name of Denticula stau-
rophora. Soon afterwards, two or three other evidently
nearly allied diatoms were observed by Professor Walker-
Arnott and myself in Californian guano; and my attention
having been thus attracted to these remarkable forms, I lost
no subsequent opportunity of searching for them, both in
guano preparations and recent gatherings. Some I have de-
tected in a gathering obtained by washing small alge picked
up on the coast of Jamaica; and several very interesting
species occurred in the scrapings of conch shells from Nassau,
New Providence, kindly sent to me by Mr. Norman, of Hull.
The Caribbean Sea appears to be particularly rich in Diato-.
macee; and there can be no doubt that this curious little
group will be further enlarged when observers shall have been
supplied with additional materials from its shores.*

With regard to the affinities of this genus, it seems to be
most nearly allied to Odontidiwm and Denticula; but the
presence of vittze constitutes an important difference. In the
place of costz, also, the species are furnished in almost every
instance with conspicuous moniliform striz. There is, how-
ever, in P. ornata an approach towards the coste of Odonii-
dium. The striz are generally interrupted. The vitte are
composed sometimes of a centrical pair; sometimes with the
addition of a solitary one at each extremity of the valve; in
one case of a centrical pair, with an indefinite additional
number.

* T take the opportunity of recommending that those who are interested
in this subject, and have friends in the West Indies, should endeavour to
prevail upon them to collect the smaller sea-weeds, especially such as are
cast ashore in quiet bays and creeks. It should be explained to them that
the ubject is not the sea-weeds themselves, but the diatoms to be obtained
from them, and that those sea-weeds are to be preferred which are covered

VOL. VII. 8

208 GREVILLE, ON PLAGIOGRAMMA.

PLAGIOGRAMMA, Grev.

Frustules quadrangular, direct, two or more united into a
filament; valves linear or elliptical; strize moniliform ; vitte
two or more, pervious, parallel with the strie.

Section I.—Vittz 2, centrical.

1. P. gregorianum, Grev.—Valve elliptical, obtuse ; strize
pervious, 18 in ‘001; frustule in front view somewhat dilated
in the middle; length -0014” to :0030."” (Pl. X, figs. 1, 2.)

Denticula staurophora, Greg., ‘'Trans. Roy. Soc. Ed.,’ vol.
xxl, p. 496, pl. x, fig. 37.

Dredged in Loch Fine, by Dr. Gregory. LLamlash Bay,
Island of Arran.

This was justly regarded by the late Professor Gregory as
a very curious little diatom, nothing similar to it having been
previously noticed. As far as I have had an opportunity of
examining the side views of the different species, this is the
only one which possesses pervious strie. It is scarcely
necessary to remark that, as the centrical vitte which
Dr. Gregory regarded as a stauros, are characteristic of all
the species, I have been under the necessity of changing the
specific name.

2. P. gamaicense, nu. sp., Grev.— Valve ..... ? frustule
in front view with the sides straight; length 0024”; striz
continued almost quite up to the angle, 16 in ‘001. (Fig. 3.)

Jamaica, in washings of alge.

As I have not succeeded in obtaining a side view of the
frustule, I am unable to give a satisfactory definition of this
species. The vitte, however, are only centrical, and it is
certainly distinct from the preceding. The strize can scarcely
be termed strictly moniliform, but rather moniliform costate.
I have another form belonging to this section, also from
Jamaica, the frustules of which are ‘0020" in length, and the
band of striz considerably narrower; the striz themselves
21 in 001". It may be a different species, but having only
seen the front view, I dare not venture to introduce it as
such.

3. P.? tessellatum, n. sp., Grev.—Valve narrow-elliptical ;

with parasites and entangled with zoopbytes, forming what the mere col-
lector of algee would call unsightly tufts. They must on no account be washed,
but dried in the rough, just as picked up, and then packed in coarse paper.
Small parcels of this kind (a few ounces in weight), from the coasts of the
different islands (and from different localities of the same island), could not
fail to produce objects of the highest interest to the diatomist.

GREVILLE, ON PLAGIOGRAMMA. 209

strie interrupted, composed of large subquadrate granules,
8 in ‘001"; length of frustule 0040”. (Fig. 7.)

In Californian guano.

A single example of this most remarkable diatom is all
that I have seen; and I introduce it with considerable hesi-
tation, for I am by no means satisfied that it belongs to the
present genus.

Section II.—Vittz 2, centrical, and one at each end of the
valve.

4. P. pulchellum, un. sp., Grev.—Valve linear-elliptical,
obtuse ; striz interrupted, robust, conspicuously moniliform,
11 in -001”; length of frustule -0025"” to -0057”. (Figs.
4—6.)

In Californian guano; Jamaica, in washings of alge ;
Nassau, New Providence, in scrapings of conch shells.

Of this fine species I have seen as many as five frustules
united in a chain, but this is extremely rare; for their cohe-
rence in the whole genus seems to be very slight. The
terminal vitte are rather distant from the extremities of the
valve, and two or three faint and short striz are seen on the
side of the vitta next the apex. The striz are very strong,
and conspicuously moniliform. It will be perceived how
greatly this species varies with regard to size; but I can-
not detect any real difference between the large frustule
represented at fig. 6 and the smaller ones forming the chain
at fig. 5. There is another form, of which I have only seen
the front view, which differs in the striz being shorter and
slightly more numerous (13 in ‘001"). It occurs in Califor-
nian guano and in the West Indies.

5. P. validum, un. sp., Grev.—Valve linear, slightly di-
lated in the middle, rounded at the ends; striz interrupted,
conspicuously moniliform, 12 in ‘001"; length of frustule
"0055", breadth -0007”. (Fig. 8.)

In Californian guano.

As in the preceding species, I have only seen the side view
of this diatom, the character of which is abundantly dis-
tinct. The valve maintains its breadth to the extremities.

6. P. ornatum, u. sp., Grev.—Valve ...? striz in front
view of frustule broad, moniliform-costate, 8 or 9 in ‘001";
connecting membrane with longitudinal rows of dots 15 in
001"; length of frustule -0052". (Fig. 9.)

In Californian guano.

210 GREVILLE, ON PLAGIOGRAMMA,

An exquisitely beautiful object, first pomted out to me by
my friend Professor Walker-Arnott. I have not seen the
side view ; the specific character must consequently remain
for the present imperfect. ‘The front view, however, is amply
sufficient to separate it from any of the species described in
this paper. The striz are very peculiar, broad, and appear-
ing almost like flat plates to the eye; indeed, at first sight,
they might be taken for costz, but they are in reality com-
posed of two or three pieces, two only being often visible.
Two abbreviated striae are situated between the terminal
vittee and the angle of the frustule, the last one being a
mere spherical granule. What importance may be attached
to the beautiful rows of dots, analogous to those which
occur in the connecting membrane of some Biddulphia, I
am quite unable to say. As they are not present in any of
the other species where I have been able to examine the
front view, it is reasonable to conclude that they are cha-
racteristic of the present form. It can scarcely be assumed
that they have any connexion with the striz, as they do not
correspond numerically. The terminal vitte in this species
are liable to be overlooked in a hasty examination, but they
come out quite distinctly with careful adjustment.

7. P. inequale, n. sp., Grev.—Valve ...? terminal vitte
in front view longer than the centrical ones, and inflected at
the apices; length -0014” to :0016"; striz moniliform, 16 in
001. . (Fig. 10:)

Jamaica, in washings of alge; Nassau, New Providence,
in scrapings of conch shells.

It is fortunate that although, as in several of the preced-
ing species, the side view is unknown, the front view should
possess such well-marked features. At the first glance the
eye is struck with the arrangement of the striz into, as it
were, two distinct groups, caused by the centrical and terminal
vittee being somewhat approximated, and the intervals be-
tween them being filled up with the strie. The inflected
apices of the terminal vitte, and the blank space between the
centrical vittee, contribute to produce this effect. Another
remarkable peculiarity is caused by the unequal length
of the vittze; the terminal ones are the longest, their points
being inflected inwards; so that the ends of the striz form
an oblique line, descending from the points of the terminal
to those of the centrical vitte. Then, again, the boundary
line of the connecting membrane follows on each side the
direction of the outline formed by the ends of the striz, and
the result is more or less of a rhomboidal figure, of little

GREVILLE, ON PLAGIOGRAMMA, 211

value in the diagnosis, but adding to the singular aspect of
the frustule. It seems to be ver y rare in both stations.

8. P. pygmeum, n. sp., Grev.— Minute ; valve narrow-ob-
long; length -0012"; strie moniliform, 21 in -001”. (Fig.
11. y

Nassau, New Providence, in scrapings of conch shells.

This diatom is distinguished among its congeners for its
minute size, its shape, and the small number of striz ;
for although they are, in the relative proportion assigned
above, there are, in fact, but few in the entire frustule.
The valve is not unlike the lower valves of some small
Achnanthes, but the decided terminal vitte serve at once
to indicate other affinities.

9. P. obesum, n. sp., Grev.—Minute; valve broadly di-
lated in the middle, the ends rounded; length -0022”,
breadth -0009"; strize 11 im -001". (Figs. 12, 13.)

In scrapings of conch shells, Nassau, New Providence.

The inflated appearance of the valve and the small number
of strize render this a well-marked species.

10. P. lyratum, n. sp., Grev.—Valve contracted in the
middle, then dilated and narrowly lyriform, linear and
rounded at the extremities; length 0042”; strie 18 in ‘001”.
(Fig. 14.)

In scrapings of conch shells, Nassau, New Providence.

The variety of contour exhibited in the valve of this and
_ the preceding species is a striking illustration of the neces-
sity of obtaining a side view of the frustule in order to
make up a complete character, although a sufficient pro-
visional character may sometimes be furnished by the front
view. ‘The present diatom, the most beautiful and remark-
able of its genus, seems very rare, as I have only met with
one example.

Section I1I.—Number of vittze between the two centrical
ones and the ends of the valve indefinite.

ll. P. californicum, un. sp., Grev.—Valve linear, rounded at
the ends; vittze between the centre and apices 3—5 ; length
"0030" to -0038"; strie 18 im 001”. (Figs. 15—17.)

In Californian guano.

The only species which has come under my notice belong-
ing to this section.

212

On the Structure and Movs of Formation of the Drentar
Tissues, according to the PrincipLe of ‘ MoLecuLaR
CoaLescENce.” By Grorce Rainey, M.R.C.S., and Lec-
turer and Demonstrator of Surgical and Microscopical
Anatomy at St. Thomas’s Hospital.

In a paper contained in the ‘ British and Foreign Medico-
Chirurgical Review,’ for October, 1857, “On the Elementary
Formation of the Skeleton,’ I have intimated that the
globular form of dentine noticed by some of the later
writers on the dental-tissues, is the result of the same
process of molecular coalescence as that by which bone
and shell are formed; and that the so-called ‘ dentinal
tubules” are merely spaces bounded directly by the den-
tine-fibres, and the partially coalesced dentine - globules.
As, at that time, I was not aware that a similar view of the
nature of these passages had been published by M. Rasch-
kow, any observations of mine, however demonstrative of
the fact, can only be regarded as confirmatory of his. This
view of the nature of these passages had, to my knowledge,
no supporters among those who had written upon the subject
in this country, being supposed to have its origin entirely in
the fibrous appearance presented by dentine under a low
magnifying power, and thus Raschkow’s view was passed over
as incorrect. I may remark, that as there are few structures
which have been so minutely and carefully examined as the
dental tissues, it must follow, that so far as microscopical
appearances are concerned, it will be impossible to add much
to what has, with more or less minuteness and accuracy,
been described, and therefore I shall have but little to com-
municate strictly of an anatomical character which will be
new. But originality in this respect is not, im this commu-
nication, my object, which is to give the proper interpretation
of appearances already described, and to show that they
admit of being accounted for, and their mode of formation
demonstrated on the same principle of molecular coalescence
as has been applied to the formation of shell-tissues. I
may further notice, that as this article must be as brief as
possible, only such details of the structure of the dental
tissues, and the organs concerned in forming them, will be in-
troduced, as are absolutely necessary to render the physiolo-
gical observations and explanations intelligible.

In discussing the subject, two descriptions of parts will
require to be considered; namely, the tooth itself, and the

RAINEY, ON DENTAL TISSUES. 213

organs concerned in its formation. The latter comprises the
dentine-pulp, the enamel-pulp, and the osteo-dentine or
bone-pulp. These are all composed of areolar tissue, vessels,
and nerves, and are provided each with an epithelium. The
former consists of a hard part, made up of dentine and
enamel, and a soft part. This latter is limited to the im-
mature organ, and, having the same relation to the calcified
portion of a young cusp that the membranous edge of a
flat bone has to the ossified part, I shall call it the mem-
branous matrix of the cusp. This being the part where the
process of calcification commences, and on which the pro-
gressive stages of that process admit of being easily ex-
amined, it will require to be described with some degree of
minuteness. And to make this perfectly intelligible, a general
view must first be taken of all the parts concerned in the
formation of a cusp, and of the cusp itself. This will be
best done by referring to the following diagram (fig. 1),
which is intended to represent all the parts as they are
found in the ossifying cusp of a mammal before the tooth has
passed through the gum. °

c, capsule ; e-p, enamel-pulp; d-p, dentine-pulp; m, matrix, undulated,
and dividing into e-m, enamel-matrix, as the external, and d-m, dentine-
matrix, as the internal layer; e, enamel; d, dentine.

A cusp, in which the process of calcification has made but
little progress, is best adapted for this examination. In
such a cusp, when seen by a low magnifying power, a mere
shell of tooth-substance, with a membranous border ex-
tending from its lower margin—the membranous matrix—is
distinguishable. (Pl. XI, fig. 4). The relative proportions
of the hard and soft parts will vary as a cusp approaches the

214 RAINEY, ON DENTAL TISSUES.

state of a perfect tooth, the latter retaining nearly the same
width until the process of calcification is completed. How-
ever, I may notice, that in a cusp about one eighth of an
inch in length, taken from a feetal calf, the membranous
border constituted at least a tenth part. This structure,
when all the parts of an uncut tooth are in situ, is situated
between the enamel and dentine pulps, its surfaces bemg
respectively in contact with the corpuscles of each and its
free margin lodged in the groove formed by their union, to
which groove it is united by exceedingly fine connective
tissue. The surface of the membranous matrix is not smooth,
but pitted, and the lateral borders appear to be undulating,
these presenting the same irregularity of form as that pre-
sented by the surface of dentine which is in contact with the
rods of enamel. Before calcareous particles begin to be de-
posited on the membranous matrix, it has no appearance of
being divisible into layers; but afterwards its division into
two layers can be demonstrated, one layer following the lower
surface of the layer of enamel in progress of formation, and
the other the corresponding surface of the incipient layer of
dentine. Its presence in these situations after a time be-
comes obscured by its intimate connexion with these tissues.

In fact, one layer may be regarded as the membranous
matrix of the dentine, and the other as the membranous
matrix of the enamel. But this will be better understood
when the process of calcification is considered. As respects
the structure of this part, it seems to me to be more allied
to cartilage than to any other description of tissue, although,
in its anatomical characters, it differs materially from it.
The membranous matrix appears to be made up of very
delicate flattened corpuscles of different shapes and sizes,
but generally longer in the vertical than in the transverse
direction of the cusp. Near its lower part these corpuscles
are imperfectly defined, and in all parts of it they are
partially separated by spaces more or less distinct in different
cusps, and in different parts of the same matrix. The matrix,
when in situ, bemg contiguous to the dentine and enamel
organs, has, after its removal, frequently patches of their
corpuscles left upon it, which, from their distinctness, and the
regularity of their form, cannot be mistaken for those of the
matrix itself.

Having now described this part with some degree of
minuteness—though not, I conceive, more so than is com-
mensurate with its physiological importance, inasmuch that
it not only presents the earliest conditions both of dentine
and enamel, but is also the part on which the process of

RAINEY, ON DENTAL TISSUES. 215

calcification can be examined with the greatest facility—I
shall proceed to consider the process of calcification and the
mode of formation of the hard parts of a cusp; and shall
first speak of the structure of dentine and its mode of
formation.

As the structure of this tissue owes its histological
characters to the manner in which it is formed, the account
of the mode of its formation will best precede that of its
structure ; and, therefore, I shall give first the process by
which it is formed. The first microscopic indication of the
presence of dentine is the appearance of very minute, and
more or less scattered, bright particles on the inferior surface
of the membranous matrix, a short distance from its lower
border. They are far too minute to admit of accurate
measurement, appearing merely like very fine particles of
dust (fig. 3 6). Examined nearer to the hard part of the
cusp the dentine-particles are seen to be larger, and of a
more or less rounded form, and, in the cusp of the feetal calf,
to be arranged in lines of partially coalesced globules (fig.
8c), but at the free border of a half-ossified fang of human
tooth they are collected into globular masses. The com-
ponent globules of which being, as in the lines, only imper-
fectly coalesced, spaces, generally considered as tubules,
are left between them. Afterwards, a still further coa-
lescence taking place, the lines, which before consisted of
strings of globules, are now become long fibres, or rods of
dentine. Now this process, in point of principle, is exactly
the same as that which takes place in the calcification of the
claw of the lobster, of which any one can convince himself
who will take the trouble to examine that part in the proper
manner. The intervals between the rods, if traced back-
wards, will be seen to end in, or rather to become continuous
with, those between the larger rounded portions of dentine,
and these, with the interstices between the smaller granules ;
and thus these spaces diminish in size, but increase in number,
until they are lost among the dusty-looking particles first
described. These spaces, severally situated either between the
rods of dentine or between the partially coalesced dentine-
elobules or granules, are the so-called “dentinal tubules,”
which, by writers upon the dental tissues, are said to have
appreciable walls or parietes. As I believe that the intervals
im question are merely spaces between the uncoalesced rods
of dentine, exactly like those between the rods of enamel, I
shall proceed to give my reasons for entertaining this view.

And this being the negative side of the question, I may
adduce the following argument. Now, as during the entire

216 RAINEY, ON DENTAL TISSUES.

progress of formation of all the so-called “ dentinal tubules,”
a portion of dusty-looking material—incipient dentine—
always intervenes between the partially formed tubules and
the dental pulp, all the fluid which is contained in their
interior, must have first passed through mere interstices
or spaces. Hence if at this, the most important epoch of a
tooth’s formation, mere spaces have sufficed for the con-
veyance and supply of interstitial fluid to its substance, I
do not see why parietes should be afterwards added to those
spaces; as by such an addition a complex form of structure
would be superadded to a simple one, after the tooth-tissues
had ceased to perform any obvious organic function, their
office being purely mechanical; and thus this substitu-
tion of tubes with parietes for mere spaces would come
too late to serve any obvious purpose. In other parts where
tubes exist, as in the tracheze of insects, or ducts of glandular
organs, a function is performed entirely distinct from that
which was required to build up these parts—and one obviously
requiring such a system of tubules. But the spaces between
the dentine-fibres and between the dentine-globules do not
come under this category, but appear to be merely a form of
interstice, suited to the character and form of the tissue in
which they exist, and so to be strictly analogous to the spaces
between the rods of enamel.

As respects the proofs resting upon facts apparent from the
examination of dentine by the microscope, I am convinced
they are sufficient to satisfy any one who will examine the
subject with impartiality. It may not be out of place here
to state that the microscopic examination of the dental tissues
is far more easy than is generally supposed. For the
successful investigation of this subject foetal teeth, perfectly
fresh, are indispensably necessary, and these can be obtained
almost at any time. I have especially examined those of the
calf as being most easily procurable. It will not be necessary
that the investigator should grind and polish sections of all
the teeth which he examines; however, it will be advisable
that he should possess two perfect sections, which can be
easily procured from the opticians. I make these remarks
rather to encourage those who are afraid to undertake the
subject from the supposed difficulty of making suitable pre-
parations, than to dissuade any one from using his own fingers.
Sections of decalcified dentine, examined in glycerine, are
very useful, and can be made without any difficulty. It has
been stated, that even and regular sections cannot be made of
teeth softened by an acid. This does not in the least agree
with my experience. A very convenient way of decalcifying

RAINEY, ON DENTAL TISSUES. Pay

teeth in the shortest space of time, and with the feeblest acid,
is to suspend them by a thread in a moderately large quantity
of the acidified fluid. One part, by measure, of hydrochloric
acid, with twelve of water, will serve very well for this
purpose; but the solution may be weaker if preferred.
Globular dentine of the human tooth, as observed by Mr.
Salter, may be easily obtained by introducing the point of a
penknife into the hollow of a half-grown fang and scraping
its inner surface ; or, which is better, by chipping off the free
edge of the opening into the fang.

The previous decalcification will not be applicable to
enaniel, which, containing so little soft material, 1s lacerated
and torn into pieces by the effervescence occasioned by the
action of the hydrochloric acid upon the carbonate of lime it
contains. However, this tissue is well seen in young cusps, as
will be shown hereafter. For the examination of the true
nature of the so-called dentinal tubules, the sections of the
decalcified dentine must be of different kinds; some being
parallel with the pulp-cavity, and others at right angles to it.
In such sections, when compared with similar ones of teeth
not decalcified, it will be seen that the form and bulk of the
decalcified dentine-rods and -globules are not altered, and that
they are only distinguishable from those of the perfect
dentine by an inferior degree of brightness. This gives an
advantage to the decalcified specimens when employed for
microscopic purposes. The exact form, extent, and precise
situation of the dentinal interspaces are best defined in these,
in consequence of the lower refractive power of the material
by which they are surrounded interfering less with accurate
definition. By such a mode of procedure it will be seen that
dentine is made up of solid rods or fibres of a quadrilateral
figure (fig. 6) running in different directions from the pulp-
cavity towards the external surface, some being parallel with,
others at right angles to that cavity, and a third set passing
in all the directions intermediate between these extremes. At
each of the four angles of all these rods a space, or so-called
tubule, exists (fig. 6 6), being formed by the meeting of the
four adjacent angles of the four contiguous rods (fig. 6 a).
This interval is more or less limited to the pomt of conflux
of these rods in different parts of a tooth, the difference
depending upon the degree of coalescence of contiguous rods.
Sometimes it extends some distance between each two adja-
cent rods, whence the appearance of a dichotomous division
of a space is produced. On the contrary, in other parts the
coalescence of the adjoining fibres or rods is so complete,
that not only the spaces between the apposed surfaces of the

218 RAINEY, ON DENTAL TISSUES.

rods, but also the intervals at the junction of their angles, are
obliterated. In such cases dentinal tubules are said not to be
present. Now when a thin section is made through such an
assemblage of fibres and passages as above described, and as
represented in Pl. XII, fig. 6, the cut rods will present
sections of various forms, some will be nearly square, others
diamond shaped, and a third set linear ; these forms depending
upon their several directions —and from what has been
before stated concerning the directions of these fibres, it
is obvious that the forms will gradually pass one into the
other. /
The subjoined diagram (fig. 2) representing a vertical sec-
tion of a tooth at a more advanced stage than the former

Fig. 2.

e, enamel; d, dentine; o-d, osteo-dentine; g-d, globular dentine ; m, ma-
trix. The horizontal line represents the part from which the section, a
portion of which is figured in Pl. XI, fig. 6, was taken.

one, will illustrate the various points spoken of, as well as
the reason for the different forms on section of dentine-rods.

Now if these rods had inclosed tubes of the form repre-
sented in plates intended to show them, their sections must
have presented first circular areas, and then ovals, becoming
gradually more and more excentric until they ended in straight
lines. But such is not the case; the sections of these spaces,
at first more or less circular, become angular or arrow-shaped,
the before-mentioned lines diverging from the angular point
losing themselves between the contiguous rods, the depths to
which these lines extend depending upon the amount of their

RAINEY, ON DENTAL TISSUES. 219

coalescence. Where the rods are imperfectly formed, being
made up partly of globular portions, then the passages run-
ning between them will partake of the same form, and an
appearance of anastomosis will result. If the fibres should
take a flexuous course, then the contour of the quadrilateral
areas will be more or less curvilinear. In fact, it is certain
that, if a body were made up of square rods placed side by side,
and so inclined towards one another as to assure all directions
between a vertical and horizontal axis, ani if, at the conflux
of every four, there was a minute space, which passed more or
less deeply between each adjoining pair, such sections made
through this body, as have been directed to be made through
the decalcified dentine, would exhibit the same appearances.
The appearance presented in transverse sections of dentine,
of rings with a dark point im the centre, has been too exclu-
sively regarded as satisfactory proof of the existence of dis-
tinct tubes. It is well known, however, that this appearance
is delusive, and not to be depended upon. In proof of this I
have only to adduce the structure of the silicious cuticle of
the common cane, and the appearance which it presents under
the microscope. This is best seen in cuticle which has been
boiled in nitric acid. The structure is made up of hexagonal
blocks of silica (fig. 1 a, 6), each block having within it a
flask-shaped cavity, with the narrow part uppermost (fig. 1 ¢) ;
and at the conflux of every three such blocks there is a space
extending from its superficial surface down to the layer of
cellular tissue upon which the portions of silica rest. Now
these spaces, of the true nature of which no one who has
examined them can entertain a doubt, present exactly the
same forms and appearances as have been described in the
dentine, namely, the annular, arrow-shaped, and linear forms,
according to the direction and position in which they are
viewed. Also a too great anxiety to account for all appear-
ances on the cell-hypothesis has contributed much to the
idea of the tubular nature of dentine, and thus these imagi-
nary tubules have been attributed to “ certain filiform pro-
longations of dentinal cells,’ or to their elongated nuclei.
For between cells and tubes there is considerable analogy, so
that an erroneous idea originating in the one is easily propa-
gated to the other. In this manner, probably, the fibres of
the crystalline lens have been thought to acquire a tubular
form, and hence these also are now described by Professor
Kolliker as tubes—an error which will be seen to be corrected
in my account of the structure and development of that
organ. But the chief cause of fallacy on this point is to be
traced to the erroneous notion generally entertained of the
VOL. VII. T

220 RAINEY, ON DENTAL TISSUES.

supposed physiological importance of the soft material which
is left after the action of acids on hard structures; these
residua having been regarded as the formative organs and
receptacles of the removed earthy matter. Hence has origi-
nated the idea of different kinds of dentine, as “ well-
formed consistent dentine,” “secondary dentine,” “ tubeless
and uncalcified dentine,” according to the relative quantities
of earthy matter thought to exist in combination with the
soft tissue.

Now I have no doubt but that the whole of this is erro-
neous, and that there is only one kind of dentine which,
even in its molecular state, is as perfect as it is in the so-
called tubular dentine, the latter being formed by the
coalescence of the particles of the former, exactly im the
same way as the larger globules of earthy matter occurring
in the deep layers of the shells of Crustaceans are formed by
the coalescence of the smaller ones.

As for “ uncalcified dentine,’ I know no other part of a
calcifying tooth which could be taken for such a form of
dentine but that which I have designated “ matrix’’—that
‘upon which the primary particles of dentine are precipitated ;
but it seems to me that this has no more right to be consi-
dered as dentine than the membranous border of the bones
of a foetal cranium has a right to be considered as bone.

Having now described the formation and structure of den-
tine, I will proceed to the consideration of enamel. The
membranous matrix (see fig. 8m) was described as at first
single, but soon dividing into two layers—one the dentine, the
other the enamel layer. The examination of the mode of
formation of the enamel must be commenced from the same
point, and followed in the same direction as that of dentine.
The enamel is first perceptible as extremely minute bright
particles, lying so near to the primary particles of dentine,
and so similar in appearance, as not to be distinguishable
from them (fig. 7). Soon, however, the particles of these two
substances assume their characteristic differences ; the den-
tine particles bemg known by their coalescing into rows of
globules, or congregating in spherical masses, as has been
explamed—the enamel particles by their parallel linear ar-
rangement. Sometimes the matrix is seen to divide suffi-
ciently near to its lower border to enable the enamel particles
to be distinguished from those of dentine prior to their as-
sumption of the linear disposition, as shown in fig. 8.

The particles of enamel, after becoming disposed in dotted
lines, lose much of their brightness, having coalesced into oval
flat portions, which are at first separated, but which afterwards

RAINEY, ON DENTAL TISSUES. 221

join to form continuous wavy lines. These lines, after getting
more defined and sharper, coalesce into the ordinary formsof |
enamel, in which all appearance of the antecedent stages be-
comes more or less completely effaced, or, in some cases, totally
obliterated. The verification of these facts can be easily made
by a careful examination of the cusps of the foetal calf in the
earliest stages of calcification ; and for this purpose the portion
of cusp examined should be split longitudinally into two equal
pieces, one presenting the enamel and the other the dentine
surface to the observer, so that they may be seen together
side by side. Several cusps should be split up for this pur-
pose, and the examination will be facilitated by the employ-
ment of glycerine.* It is scarcely necessary to say that this
examination requires good illumination and great nicety of
adjustment. At the commencement itwill be made more easily
by tracing the film of enamel backwards from the point of the
cusp towards the edge of the matrix. The matrix receiving the
enamel particles can generally be seen for some distance, but
it gradually disappears, becoming blended with and concealed
by the contiguous layers of enamel. The films of newly formed
enamel soon show a disposition to break up into irregularly
quadrilateral forms; but in no instance have I met with re-
gular hexagons, as described by some authors. The laminated
character of dentine and enamel will, from the explanation
just given of their mode of formation, admit of being easily
accounted for; the degree of its distinctness depending upon
the completeness or incompleteness of the coalescence of the
dentine and enamel particles, will vary in different teeth.
Some occasional appearances also, such as very distinct inter-
globular spaces about the extremities of the laminz ; and the
lines called contour lines or markings, will be explicable on
the same principle ; as well as the homogeneous form of
enamel found in some animals, and the absence of any appre-
ciable spaces in some parts of all teeth, the dentine being in
these parts said to have no tubules, as before noticed.

The next dental tissue is the osteo-dentine or “ crusta
petrosa.”” The mode of formation of this structure can be
beautifully seen in the molar teeth of the foetal calf at the
free margin of the pulp-cavity, where a thin scale of this sub-

* T have not had an opportunity of judging whether these would preserve
their natural appearance if kept in glycerine for many months. But I may
observe that 1 had a piece of oyster-shell which showed beautifully the
coalescing carbonate of lime by polarized light; of which I put one piece into

, Canada balsam, and the other into thick glycerine—the former remains now
as when first. put up, but the latter, after some months, began to lose its
natural appearance, and now the large globules of carbonate have altogether
disappeared.

222 RAINEY, ON DENTAL TISSUES.

stance is found partially filling up the opening in the fang.
This, which resembles ordinary bone, is formed on a me n-
branous matrix, directly contmuous with and similar in strue-
ture to that of the dentine; and the primary particles are
so like dentine-particles, as only to be distinguished from
them by the manner in which they afterwards become
arranged. These particles appear to coalesce in the same
manner, but in the place of taking a rectilinear arrange-
ment, they have somewhat of an arborescent form, the
small spicular branchings of which anastomose, and inclose
areole of a more or less circular form. These may be re-
garded either as Haversian canals, lacune, or canaliculi,
according to their size and shape, and the circumstance of
their containing, or not, vessels; in which case they must
of course be regarded as Haversian canals. As I have else-
where described the structure and mode of formation of
bone, I do not think it necessary to go further into this sub-
ject. The crusta petrosa being considered by all anatomists
as bone, I have called the vessels and epithelial corpuscles in
contact with its matrix “the bone-pulp,’ and thus the
analogy between bone and dentine is preserved; the pulp-
cavity of a tooth corresponding to a true Haversian canal,
the spaces between the dentine rods to the lacunz, and the
extensions of these spaces between uncoalesced portions of
dentine to the canaliculi of common bone. The enamel pre-
sents similar analogies, but these are much less obvious
and striking.

In this paper I have, so far as I have gone, confined
my observations to matters of rational inference, and such
facts as can easily be verified by any one who will take
the trouble, but my observations would be incomplete if
something were not said of the functions of those parts which
are indirectly concerned in the formation of the several
structures which have been described. These are the dentine-,
the enamel-, and the bone-pulps, and the part which has
been designated membranous matrix. What I shall advance
upon these points must of course be theoretical, and there-
fore to be valued only according to its degree of probability.
These pulps being composed of epithelial corpuscles (I prefer
the term corpuscle to cell, as there is nothing hypothetical
in its meaning), and abundantly supplied with vessels, as
well as containing nerves, are doubtless the organs by which
the materials composing the dental tissues are elaborated.
Tt is observed in Kolliker’s ‘ Manual of Histology,’ that the
reticulated connective tissue of the enamel-pulp contains
in its meshes a great quantity of fluid rich in albumen
and mucus. This fact I have myself noticed. And I have

RAINEY, ON DENTAL TISSUES. 223

further found, when the jaw of the foetal calf with the tooth-
sacs entire within it, had been kept until decomposition
commenced, that on opening these sacs the cusps were
coated in parts with phosphate-crystals sufficiently large to
be visible without the aid of the microscope. This circum-
stance is most probably due to the decomposition of some
animal substance required to keep the phosphates in solution,
and the subsequent dissipation of its elements in the condi-
tion of carbonate of ammonia, &c. Now, if we suppose that
this albuminous fluid, holding in solution phosphates and
some of the other constituents of enamel, elaborated by the
enamel-organ, be applied by the ends of the enamel-cor-
puscles, to the external surface of the previously formed
layer of enamel-matrix ; and that this matrix is moistened
by a fluid containing in solution a salt or salts capable of
decomposing those furnished by the enamel-organ, and so
combining with them as to precipitate coalescing particles of
enamel such as have been described, we shall have, in
principle, exactly what takes place in the formation of shell-
tissue. (See this demonstrated in my work ‘ On the Forma-
tion of Shell and other hard structures.’) As to the manner
in which these organs act in elaborating their respective
substances with the albumen necessary to give them their
globular coalescing property is not at present known, and
a more refined chemistry than has yet been applied to this
branch of physiology would be required to throw light upon
the subject. What has been stated in reference to enamel
and the enamel-pulp will apply equally to dentine and its
pulp, as also to bone, as has been shown in the article
“Bone,” in the volume before alluded to. As in the preced-
ing explanation of the mode of formation of the dental
tissues, no mention is made of any influence but what is
chemical and mechanical, it is probable that if this paper
were thus to conclude, it would be inferred that I had no
belief in the participation of vitality in the several processes
concerned in the production of these tissues; and thus an
opportunity would be afforded of representing all that has been
stated as absurd and ridiculous. Consequently a few remarks
on the influence of vitality in the processes above explained
will be necessary. Now, it is certain, from the foregoing
account of the formation of the dental tissues, as observed
in tracing their development from the condition in which
they are found on first assuming a visible existence up to
their completion, that both chemical and physical effects
have been produced,—that new compounds have been formed
is a proof of the one, and the definite forms which have

224 RAINEY, ON DENTAL TISSUES.

been taken up by their aggregated molecules are a proof of
the other. Hence, the probable questions which will arise
are,—whether these effects are entirely due, to the direct
and sole influence of vitality, or to the exclusive operation of
physical forces? In my opinion neither of these views is
correct, and one is just as untenable as the other. I am not
aware that the latter has any advocates, but I believe that
the former is the view generally entertained by physiologists,
and that the strictly physiological part of the cytoblast 'theory
is based upon it. To me the truth seems to be between the two
extremes, the above-mentioned chemical and mechanical effects
being, in my opinion, produced directly by physical and mecha-
nical agency, but under the control of a general vital principle.
According to this view, the function performed by the nu-
cleated corpuscles of enamel-, dentine-, and bone-pulp, is
chemical, each individual corpuscle being designed to ela-
borate a material whose elements are brought to it by the
blood-vessels. Now, it is no more improbable that there
should be in the bodies of animals a strictly chemical appa-
ratus than an electric one, as in the Torpedo, or an optical
one, as exemplified by the dioptrical parts of the eye.
Indeed, not only animal, but vegetable structures perform
an endless variety of chemical operations, and ought, there-
fore, likewise to abound in chemical apparatus. And it is
in no way inconsistent with analogy to suppose that the
nucleated particle found in the earlier states of vegetable
cells is strictly an organ of this kind, and analogous to a
nucleated corpuscle of the enamel-organ, and not a mere tran-
sitional form of vegetable tissue, as some suppose. ‘This sub-
ject I hope to consider more fully in another communication
in a subsequent number of the journal, showing the applica-
tion of the principle of molecular coalescence to the formation
and structure of starch-granules. It may be further observed
concerning the influence of vitality, that if the form of a
perfectly developed tooth be considered in reference to its
adaptation to the place and circumstances under which
it is designed and required to act, it will be at once obvious
that not only a vital, but an intelligent principle has been
concerned in originating and directing the chemical and
mechanical forces to which it owes its construction. And
further, as the size and shape of an entire tooth depends
upon the number, form, and arrangement of the several
parts composing it, it is a fair inference that the same design
and intelligence which originate and direct the construction
of the whole, also originate and direct the physical pro-
cesses concerned in the formation of the parts ; and that,

CURREY——-MYCOLOGICAL NOTES. 225

not indirectly, and with the co-operation of deputed and
hypothetically endowed material particles, called “nuclei or
cell-germs,” but by a direct exercise of power and wisdom.

MycouoeicaL Notes.

By Freperick Currey, Esq., M.A., ESR:S:) FLE.S.

Tue contents of the following pages are strictly in accord-
ance with the above title, consisting of a number of detached
observations which have been entered from time to time in
my note-book, and which are here brought together in the
hope that they may prove interesting to those botanists whose
attention has been directed to the Fungi.

Graphiola Phenicis, Poit.—By the kindness of Sir William
Hooker I have had an opportunity of examining good
specimens of this fungus, the history and systematic position
of which have hitherto been somewhat obscure. Graphiola
Phenicis is a fungus which affects the leaves of Palms, and
which at first sight presents the appearance of a small flat
disc, of a yellowish colour, surrounded by a black border,
strongly resembling a Peziza or Patellaria. From the surface
of the disc threads or fibres are frequently seen protruding,
but these are by no means always to be found. A vertical
section of the fungus, when magnified, shows clearly that the
yellow disc is not imbedded in a cup, but is only surrounded by
a ring of black carbonaceous matter. Fig. 2, Pl. X1, shows a
vertical section slightly magnified, and fig. 1 a similar section
of a much more open disc more highly magnified. In this
latter figure, a represents the black outer crust, which, as
has been stated, is aring and not acup. This black ring I
suspect to be formed of the disorganized tissue of the leaf,
and not to belong to the fungus itself. 61s a grumous layer,
formed either of very minute cells or of granular matter; c,
elongated cells of the tissue of the leaf; d, inner roundish
cells of the tissue of the leaf; e, delicate, closely packed
threads, springing from the granular layer and marked with
very faint transverse lines or septa; f, a mass of yellowish
small spores resting on the threads, and doubtless formed by
the breaking off of the terminal cells of the threads. The

226 CURREY——MYCOLOGICAL NOTES.

threads or fibres, which, as | have mentioned, are often seen
protruding from the surface of the yellow disc, are, I am
satisfied, portions of the tissue of the leaf carried upwards by
the growth of the fungus, and have no real connection with
the parasite. Fig. 3 represents a specimen of the fungus
deprived of its outer black ring, and in which these fibres
are very numerous, traversing the vast heap of conglomerated
loose spores which form the dise in every direction. This
figure is magnified about fifty diameters. If the above view
of the structure of the plant be correct there can be little
doubt, I think, that its proper place is in the tribe of the
Uredinez ; and in this view I am fortified by the opinion of
M. Tulasne, who, in speaking of Graphiola, says—‘‘ Si eum
Uredinei nostrates admiserint, sibi, ut opinor, socium maxime
abnormem ac de specie vix consentaneum, licet fortassis
revera legitimum adsciscent.” At the same time I cannot
but feel doubtful as to the systematic position of a plant
which by different botanists has been associated with such
various genera as Lycogala, Cicidium, Hypoxylon, and
Phacidium; and the more so since I know that Dr. Montagne’s
observations (which I hope will shortly be made public) have
led him to different conclusions.

Phragmidium bulbosum.—In the fifth volume of the ‘ Mi-
croscopical Journal’ I have recorded some observations upon
the structure and germination of the spores of this fungus,
and have also noticed a peculiar mode of germination which
took place in a closely allied plant, viz., Triphragmium
Ulmarie. In the germination of the Phragmidium a fila-
ment proceeds from each (so-called) joint of the spore, which
filament becomes divided by septa at the extremity into
several cells, and from these cells secondary filaments are
protruded, which are crowned by small globular vesicles of a
brilliant orange colour, as shown in Plate VIII of vol. vy,
figs. 18, 19; and I have now to notice (what perhaps might
have been anticipated) that it is not necessary, in order to
produce germination, that the spores of the Phragmidium
should be perfect. Fig. 4 represents a spore torn from its
stalk, im which the upper joint has thrown out its germ-
filament, and the latter, although it has not attained the usual
length, has become septate, and produced the orange-
coloured vesicles in the regular manner. Fig. 5 represents a
fragment of a spore from which two at least, if not three
joints, have been separated; but which, nevertheless, has
germinated in the usual way, and at the extremity of the
germ one of the orange-coloured vesicles is still attached.

CURREY——-MYCOLOGICAL NOTES. 22

These observations, if they do not tend to support my view of
the ascoid nature of the spores of Phragmidium, at least
show that each individual jomt of the spore has a separate
vitality, and is physiologically an independent embryo.

Fig. 6 shows a peculiar (perhaps imperfect) mode of ger-
mination in Phragmidium bulbosum, which is almost exactly
similar to that noticed in vol. v, as having occurred in
Triphragmium Ulmarie. In this instance, however, the ter-
minal cell, instead of being oblong and rectangular, has
assumed an ovoid form, and the last cell but one has thrown
out a secondary filament, upon which, however, no vesicle is
seen.

Mucor fusiger, Lk.—This mould is parasitic upon the gills
of Agarics, and is easily recognised by its large dark-brown
or greenish-brown, almond-shaped spores, which are repre-
sented in fig. 7. These spores are accompanied by a mass of
minute granules, endowed with movements considerably more
active than ordinary molecular motion. I did not observe
any ciliary appendages which would account for this motile
power ; indeed, if any such existed, they would probably not
be visible without a considerably higher power than I am in
the habit of using. It is not impossible that these granules
may be of the same nature as the spermatozoa observed in
Vaucheria and other fresh-water alge, but without further
observation this can only be suggested as a speculation, and
as a point deserving of further inquiry. Mr. Berkeley has
noticed similar motions in Endodromia. (See Hooker’s
‘Journal,’ vol. in, p. 78.)

Patellaria clavispora, B. and Br., ‘ Annals of Nat. Hist.,’
1854.—I have met with a Patellaria, growing near Tunbridge
Wells on a dead oak branch, which is, I think, identical with
the above plant, although differing slightly in the colour of
the hymenium and in the length of the sporidia. No figure
of the fructification of P. clavispora is given by Messrs.
Berkeley and Broome, and the nature of it is sufficiently pe-
culiar to merit illustration. The peculiarity consists in the
fact of the same hymenium producing sporidia contained in
asci, and also another kind of fruit which would come under
the denomination of stylospores or conidia. It is now well
known that such an occurrence is by no means uncommon in
fungi, and the existence of the double fruit in this case did
not escape the observation of Messrs. Berkeley and Broome.
Figures, however, convey much more definite ideas than
verbal description, and I have therefore thought it worth

228 CURREY— MYCOLOGICAL NOTES.

while to record these supplementary observations. The hy-
menium of Patellaria clavispora is stated im the ‘ Annals’ to
be of a brown colour. My specimens appear quite black to
the naked eye, assuming, however, a brown tinge when the
hymenium is wetted. A thin vertical section shows that
this brown colour is entirely owing to the small brown stylo-
spores or conidia which are attached to the tips of the para-
physes, and which bear some resemblance to the spores ofa
Cladosporium. ‘These bodies are represented in Pl. XJ, fig.
8 a—e, all magnified 325 diameters, except 4, which is mag-
nified 450 diameters. They are, as I have mentioned, of a
brown colour, and consist of two, sometimes three, cells; the
cells sometimes exhibiting a nucleus, as in J, d, e, sometimes
not, as in a, c. The paraphyses not unfrequently produce
two stylospores at the apex, as is seen in fig. 8 a, and are
occasionally furcate at a distance from the apex. The other
kind of fruit consists of asci containing sporidia. The
asci are linear, and the sporidia, two of which are drawn in
fig. 8 f, g, are somewhat clavate, exhibiting, when young, a
row of nuclei, as shown at f; but when more advanced they
become three- or four-septate, and have a granular endo-
chrome. The length of these sporidia I found to be 0:0014
to 0:0016 inch, a measurement exceeding that of Messrs.
Berkeley and Broome, who state the length of the fruit in
their plants to be 0°0010 inch. Mere difference of size in
the sporidia is, however, not sufficient for the separation of
species which agree in other particulars, and I therefore do
not doubt that the Patellaria here figured must be considered
the same species as that described in the ‘ Annals of Nat.
History.’

Patellaria atrata, ¥r.—I find growing very commonly upon
worked wood a species of Patellaria which I believe to be P.
atrata, of Fries, and which, if I mistake not, exhibits two
different sorts of fructification. The ordinary or perfect
fruit of the species in question is drawn in fig. 9, and consists
of asci containing eight rather’ long, fusiform, slightly-
curved, multi-septate sporidia. The specimens in which I
find the other sort of fruit do not differ materially from the
ascigerous specimens, except in being of a very much smaller
size. ‘The hymenium of these smaller plants produces no
asci, but is formed of a mass of cylindrical or clavate, septate
spores, such as are shown in fig. 10 a, b,c. If we imagine
the asci above mentioned to bear only one sporidium each,
the result would be the production of a number of bodies not
very dissimilar from the septate spores. I do not mean to

CURREY——MYCOLOGICAL NOTES. 229

say that the identity of the two plants can be considered to
be established, but there is at least good ground for the suts-
picion of a relationship between them, and it is desirable that
all such cases should be noticed, with the view of inducing
further observations.

Cenangium Cerasi, Pers.—The reproductive organs of this
and several other Cenangia have been commented on by
M. Tulasne in a paper in the last volume of the 3d series of
the ‘ Ann. des Sciences.’ He describes the pycnidia as tu-
bular processes, generally czespitose, confluent at their base,
their cavities communicating with one another. The pycnidia
contain large curved stylospores, and sometimes also (aecord-
ing to M. Tulasne) delicate curved spermatia, but the latter
I have not seen. In some specimens of Cenangium Cerasi
which I met with at Eltham, in Kent, I have observed the
pycnidia to be somewhat different from those described by
M. Tulasne, approximating, in fact, very closely to his de-
scription of those organs in Cenangium fuliginosum. The
pycnidia in my specimens formed irregular tubercles, the
substance of which was hollowed out here and there into
simple cavities, filled with stylospores growing from short
basidia which lined the walls of the cavities. Thin vertical
sections of the tubercles are represented in Pl. XI, figs. 11,
12, which show also the cavities and the contained stylo-
spores, the latter being colourless, fusiform, curved, and when
ripe (I think) triseptate. There was no appearance of the
commencement of the formation of any ostiolum or opening
for the exit of the stylospores, which I have little ‘doubt
would escape by irregular apertures, as has been observed in
Cenangium fuliginosum. There is, in fact, hardly any diffe-
rence between the pycnidia just described and those of C.
fuliginosum, except that im the Jatter they are said to be of a
dark colour, whereas in Cenangium Cerasi they are pale. It
may be that the pyenidiaof C.Cerasi, described by M. Tulasne,
were in a more advanced state than those above mentioned,
it beig quite possible that at a later period than that
shown in figs. 11, 12, the cavities might become confluent
at the bottom, and tubular by the opening of the apex. As,
however, the stylospores in my specimens were perfect, the
pycnidia must be considered as fully developed, and I have
therefore thought it worth while to notice the form of them,
as presenting a marked departure from those hitherto de-
scribed, and at the same time an approximation to those of
a nearly allied species.

230 CURREY——MYCOLOGICAL NOTES.

Spheria Zobelii, Tul., ‘ Fungi Hyp.,’ p. 186, tab. xi, fig. 1.
—The Rev. Henry H. Higgins, of Rainhill, near Prescot,
lately forwarded to me a specimen of Peziza sepulta, calling
my attention at the same time to a small parasitic fungus
growing on its hymenium. Upon examining it, I found the
parasite to be the above-mentioned Spheria, which forms a
very interesting addition to the list of British fungi. Spheria
Zobelii was first observed by Corda, growing in the flesh of
the white truffle, Cheromyces meandriformis, Vittad., and he
described it, in the fifth volume of the ‘ Icones Fungorum,’
under the name of Microthecium Zobelii. It has since been
transferred to Spheria, there being obviously no sufficient
grounds for creating a new genus for it. It was subsequently
observed by Tulasne growing over the inner surface of
Hydnocystis arenaria, a plant which was at one time supposed
to be a Peziza, but which is now placed with the Tuberacei.
Hydnocystis is, in fact, as has been remarked by Mr.
Berkeley, a mouthless Peziza, forming a passage from that
genus to the genus Tuber.

Peziza sepulta belongs to a small group of Pezize which
grow in sand or on loose earth, in which the cups are more or
less buried, and which are hardly distinguishable from
Hydnocystis.

The occurrence of Spheria Zobelii upon the hymenium of
the above Peziza might seem to indicate a further affinity
between the latter plant and Hydnocystis, in addition to that
derived from similarity (almost identity) of structure; but as
the Spheria grows also upon Cheromyces, it 1s not impro-
bable that any fungus of subterranean habit might afford
an equally fitting nidus.

In fig. 13 I have drawn the sporidia of the Spheria under
a magnifying power of 325 diameters. The sporidia are bi-
seriate, elliptical, shghtly drawn out and truncate at the
extremities, very dark brown, margined, 0:001 inch long.
Beautiful and elaborate figures of the plant and of its micro-
scopical structure are contained in the ‘ Fungi Hypogei’ of
M. Tulasne, tab. xiii.

Iam informed by Mr. Higgins that Peziza sepulta with the
Spheria occurred ‘abundantly on the sand-hills at Crosby,
near Liverpool, in November, 1857, in low and moist places,
about 300 yards from high-water mark. The Peziza was
growing in company with Agaricus maritimus, a species not
hitherto recorded as British. Mr. Higgins adds that, although
Peziza sepulta was also abundant in 1858, he did not then
see the Spheria.

CURREY——-MYCOLOGICAL NOTES. 231

Spheria Tiliaginea, Currey.—Under this name I have de-
scribed, in the ‘ Philosophical Transactions’ for 1857 (p. 545),
a Spheeria which occurs in the neighbourhood of Blackheath
upon Lime. I stated it to belong to the division Circinate,
but observed that the perithecia were more deeply immersed
in the inner bark than is usual in that division. In the spe-
cimens there described the sporidia, although fully formed,
appeared to be hardly quite ripe; in fact, the plants had not
attained their full age. I have since found, also upon Lime,
a Spheeria not distinguishable in its perithecia or sporidia
from S. Tiliaginea, and which, I do not doubt, is the same
species in a more advanced stage of growth. This latter
Spheria belongs, however, to the Circumscripte, the peri-
thecia being imbedded in a white woody stroma, and the
stroma itself surrounded by a manifest conceptaculum. The
existence of the conceptaculum would afford no ground for
separating the species from S. Tiliaginea, for it may well be
that the conceptaculum does not appear until the plants
have attained some age; and besides this, I suspect that
other species of Spheeria occur, in which the conceptaculum
is sometimes present, and sometimes not. I have referred to
this circumstance in my Synopsis of the Kew Spherie, in
the last part of the ‘Transactions of the Linnean Society,’
under S. éaleola, and need not dwell upon it here.

Within the conceptaculum above alluded to were con-
tained a number of perithecia, and the interest of the plants
consisted in the fact that some of the perithecia were
ascigerous and others stylosporous. The ascigerous peri-
thecia produced asci and sporidia exactly resembling those of
Spheria Tiliaginea, as figured in the volume of the ‘ Phil.
Trans.’ above-mentioned, pl. xxv, fig. 12. The stylo-
sporous perithecia, or pycnidia, as they ought, perhaps, to
be called, produced oblong or elliptic stylospores, sometimes
slightly incurved on each side in the middle, with a granular
endochrome, of a greenish colour, and with usually a very
distinct double outline. ‘These stylospores are drawn highly
magnified; in fig. 14 their length varies from 0:0005 to
0:0007 inch. My former observations showed that this
Spheria produced spermatia and naked stylospores, besides
the normal sporidia, and it now appears (if the species
in discussion be identical with S. Tiliaginea, of which I
have no doubt) that there is also a fourth kind of fruit, viz.,
stylospores contained within perithecia.

Spheria ciliaris, n. sp.—This Spheeria occurred on branches
of ash at Weybridge, in October, 1857, and is particularly

«
252 . CURREY—MYCOLOGICAL NOTES.

interesting, from its intimate connexion with a species of
Helminthosporium, which latter, it is probable, may be a
second form of fruit of the Spheria. In a paper in the fifth
volume of the fourth series of the ‘Annales des Sciences,’
Tulasne states in effect that Helminthosporium is not a
true genus, but only a state of Spheria, and if this be cor-
rect, there would, I think, be no doubt of the relationship
between Spheria ciliaris and the Helminthosporium to be
presently mentioned: Some botanists, however, are not dis-
posed to admit so general a view, and are inclined to look
upon cases like the present as instances of parasitism. The
question is one not yet ripe for decision, the evidence being
at present insufficient. very case bearmg upon it, how-
ever, is worth recording, if only with the view of bringing it
‘to the notice of other observers.

The ash-branches above mentioned were covered with
perithecia, concealed (with the exception of the ostiola) by
the cuticle, and many parts of them aiso were rough with
the erect hairs or threads of a species of Helminthosporium.
By removing the cuticle,with great care, I found that the
threads of the Helminthosporium proceeded from the apices
of the perithecia, breaking out through the cuticle in little
tufts. Under an inch glass the spores of the Helmintho-
sporium were easily seen attached to the tips and sides of the
threads. These spores are drawn in fig. 15 5, and are not,
I think, distinguishable from those of Helminthosporium
macrocarpum, “rev. The perithecia of the Spheria are
small and subglobose; and it is a fact worthy of notice that
the perithecia diminish in size in proportion as the hairs of
the Helminthosporium are more developed, becoming in
places almost obsolete. The sporidia are biseriate, colour-
less, narrow, pointed at the extremities, sometimes almost
almond-shaped, sometimes strongly constricted in the middle,
always (or almost always) with four nuclei, varying in size
from 0:0005 to 0:0009 inch in length. They are drawn in
the ascus, in fig. 15 a, x 315 diameters. I have called the
Spheria, Spheria ciliaris, the name applied by Sowerby to
Greville’s Helminthosporium macrocarpum. If the above
observations are sufficient, as I thik they are, to show that
the sporiferous threads and the perithecia are the produce of
one plant, the Helminthosporium will merge in the Spheria,
and Sowerby’s name should, I think, be adopted.

Spheria obtecta, n. sp.—I have in my herbarium a Spheria
(for which I am indebted to Mr. Broome) which is closely
associated with a species of Helminthosporium, the spores of

CURREY—MYCOLOGICAL NOTES. 200

which, although too far advanced for very accurate observa-
tion, did not appear to differ from those of Helminthosporium
macrocarpum. In fig. 16 b,c, I have drawn the spores of
the Helminthosporium in question, and in fig. 16 a, the
fruit of the Sphzeria, which is very handsome. The following
is the description of the Sphzeria, which, as far as I know, is
new :

Spheria obtecta, nu. sp. (Obtecte).— Perithecia round,
with a short, somewhat flat, sometimes rather gaping ostio-
lum, solitary, or in small groups, mostly quite concealed by
the bark. Sporidia biseriate, dark rich brown, oblong,
usually slightly constricted in the middle, 0:0012 to 0:0015
inch long. On Wych elm.

Spheria macrospora, Desm.—Mr. Broome has called my
attention to the frequent association of this Spheria with
Coryneum macrosporium, Berk. Ido not know whether the
fruit of this Spheria has ever been figured. In fig. 19 a,
I have drawn the sporidia, which are colourless at first,
and eventually become of an olive-green tinge. They are
3-partite or 3-septate, and surrounded by a narrow gela-
tinous envelope. The Sphzeria itself is described in the
‘ Annales des Sciences,’ series 3, vol. x, p.390; it belongs to
the Ceespitose. The spores of the Coryneum are drawn in
fig. 19 6. It seems to me not at all improbable that the
Spheeria and the Coryneum may be the produce of the same
mycelium.

Spheria stercoraria, Sow.—In this species I have ob-
served a curious process of germination, which seems worthy
of notice. It consists in the protrusion from one end of
the sporidia of an oblong or fan-shaped expansion, forming
a sort of crown at the apex of the sporidium, whilst from the
other extremity the usual elongated germ-filament proceeded.
In fig. 17 I have drawn two of the sporidia, which are still
attached to the fragment of an ascus, and both of which have
thrown out the crown from one extremity, and the filament
from the other, the former of which appears to consist of four
short colourless threads or cells compacted together. The
sporidia of S. sfercoraria are at first colourless, then of a sort
of olive-green, and eventually almost black. They germinate
as actively in the hyaline state as they do after having attained
the black colour of their full age. Their length is very
variable, sometimes reaching to 0°0010 of an inch. In the
figure the remains of the inner membrane of the ascus are
seen collapsed upon the tips of the sporidia.

234 CURREY—MYCOLOGICAL NOTES.

Spheria Spartii, Nees, ‘Fr. Syst. Myc., uu, p. 124.—
The mention of the inner membrane of the ascus leads me
to notice an instance of extreme elasticity in this membrane,
which I have seen in Sph. Spartii, Nees. This species
(which, by the way, is identical with S. elongata, Fr.) has
oblong or elliptical multicellular sporidia, of a dark yellowish-
brown colour. Fig. 18 a@ represents the ordinary state of
an ascus, with the eight contained sporidia. Fig. 18 6
shows an ascus of the same species in which the outer mem-
brane has been ruptured at the point (x), and an exit has thus
been afforded for the inner membrane, which has not, as I
think is usually the case, itself burst in the act of egress.
It will be seen, by referring to the figure, that the length of
the expanded inner membrane is at least twice that of the
outer one, whilst the breadth of each is the same. One of
the sporidia remains imprisoned at the base of the ascus, the
rest having been carried upwards by the escape of the inner
membrane. An account of the elasticity of the inner mem-
brane of the ascus in Spheria Scirpi is given by Pringsheim, in
the first volume of the ‘Jahrbiicher fiir wissenschaftliche
Botanik,’ but I cannot help thinking that his observations
require confirmation.

Phlebia mesenterica, Dicks.—M. Tulasne, in his paper on
the ‘Tremellini,’ published in the ‘Ann. des Sciences’ for
1853, mentions that he has observed the parenchyma of Nema-
telia nucleata to contain a number of calcareous concretions
of a round, ovoid, flattened, or irregular shape. These con-
cretions were very large, being about the size of a cabbage-
seed. He noticed, moreover, in 7remella recisa, Dittm., both
on its surface and in its substance, a vast quantity of very
short linear crystals. I do not know whether these bodies
have been observed in other fungi, but I am able to state
that raphides occur also in Phlebia mesenterica, Dicks. I
have found the hymenium of the latter plant covered with a
mass of crystalline bodies intermixed with the spores of the
fungus. The crystals were quite microscopic, requiring a
power of 200 diameters to exhibit them with any clearness.
Some appeared to be in the form of octahedrons, and others
of dodecahedrons. M. Tulasne speaks of the raphides of
Nematelia nucleata beg brought to the surface and exposed
by the gradual decay of the tissue, but I do not understand
him to mean that their number increased with the decom-
position of the plant. I have seen, however, an instance in
a pheenogamic plant (a species of Myriophyllum), where the
raphides increased in number prodigiously as the tissue de-

LANKESTER, ON A MUSEUM MICROSCOPE. 235

cayed. These raphides were of the stellate kind, and occurred
in the intercellular passages of the stem of the Myriophyllum.
It has been alleged,* that raphides are always contained in
cells, in contradiction to the opinion of Raspail, who stated
that they were also met with in the intercellular passages, a
statement which I am enabled to confirm from my observa-
tions on the above Myriophyllum. An account of these
raphides, with a figure, will be found in the ‘ Phytologist’
for April, 1859.

BLackHEATH Park, 8.E.;
June, 1859.

Description of a Museum Microscope.
By Epwin Lanxester, M.D., F.R.S.

In the annual address to the Microscopical Society I
drew attention to the importance of familiarising the public
with the use of the microscope, in order that they may
become acquainted with its applications. One great barrier
to its use in museums has been that, as usually constructed,
it has been easily displaced, put out of order when adjusted,
or its parts could be removed fraudulently. These evils
could only be remedied by the constant presence of a skilful
and watchful attendant. In order to obviate these difficulties
I have had a microscope constructed, of which the accom-
panying figures will give a good idea. The first object
to be secured was that of the fixity of the whole instrument.
This has been effected by attaching the stand, e (figs. 1 and 2),
to a block of wood. Fig. 1 is intended for viewing trans-
parent objects, and the stand is fixed at an angle of about
59°. Fig. 2 is intended for viewing opaque objects, and the
stand is made upright. The block, h, to which the stand is
affixed, may be screwed to a table, shelf, or other fixed
object, where there is a good light, by a couple of screws
from the bottom. This arrangement secures the instrument
from being knocked over. The eye-piece, a, is placed in the
tube in the ordinary way, but by means of a slit at the back
of the tube, which admits of the movement up and down of
a screw attached to the eye-piece, it is fixed at any point
which may be thought desirable. This screw, 6, is only

* See Quekett’s ‘ Lectures on Histology,’ p. 43.
VOL. VII. v

236 LANKESTER, ON A MUSLUM MICROSCOPE.

moved by the aid of a screw-driver. This secures the
immovability of the eye-piece. As a matter of experience,
I may state that the screw needs to be very strong, as persons
having a little knowledge of the microscope, and wishing
to display it, have made violent efforts to remove the eye-
piece, which of course 1s intended to be fixed. The object-
glass, d, is attached to the tube, and is also secured by the
aid of ascrew. Thus the only movement permitted to the

Fig. 1.

tube of the instrument is performed by a screw, e, which
moves the tube in the way of the fine-adjustment of the
ordinary microscope. As moveable slides would be liable to
accident or to be purloined, two forms of slide which are
not removeable from the microscope have been supplied.
These are fixed in the position usually occupied by the stage, f.
The slide for transparent objects is circular, and is made of
wood, and has holes bored for the reception of eight pieces
of glass on which the object is placed. A piece of thin
glass is then put over this, and the whole kept in position by
an elastic metallic ring. The slide revolyes on a metal

LANKESTER, ON A MUSEUM MICROSCOPE. 207

screw, which is attached to the holder, i, and which occupies
the place of the stage. By this means eight, ten, or more
objects may be mounted at the same time, and brought
under the object-glass by merely moving the circular slide.
The compound slide for viewing opaque objects (fig. 2 f)
is constructed on a somewhat different plan. It is a frame
into which the common glass slides, three inches by one, can
be pushed, and when it is filled up they are secured by means
of the screws, &. . The slides in their frame are then made
to move backwards and forwards in a frame attached to the
arm, 7, which is situated in the place of the ordinary stage.

Fig. 2.

Although this slide was made for mounting opaque objects
upon the upright stand, it can be equally applied to trans-
parent objects and the oblique stand.

Two of these microscopes, constructed by Mr. Ladd,
of Chancery Lane, have been at work for some weeks
in the Food collection of the South Kensington Museum,
and have excited great interest amongst those who have
visited the Museum. A list of the objects exhibited, as
numbered on the slides, is placed on the table, and
every one seeing the object can thus obtain some know-

238 LANKESTER, ON A MUSEUM MICROSCOPE.

ledge of its nature. It has also been found necessary
to write out a short label, giving directions how to adjust
the focus of the microscope by the aid of the screw on the
tube. Strangers to the instrument do not generally under-
stand the way of throwing light on the object from the
mirror below, and this should be done occasionally by an
attendant. When it is known, however, exactly where the
microscope is to be placed, the mirror might be fixed so as
to require no further adjustment. With these precautions
the instrument seems to have worked as well as I anti-
cipated, and I hope that they may be erected in other
museums; as there are, undoubtedly, a large range of objects
equally interesting to the general public, as those seen by the
naked eye, which can only be viewed by the aid of the
microscope.

The instrument described above is far from being as com-
plete and convenient as it might be; but I have been
encouraged to draw attention to it, in the hope that the
directors of museums and instrument-makers may take up
the subject, and thus render the microscope more available
for popular teaching in science than it has hitherto been. I
ought also to add that I understand instruments have been
constructed to carry out the above objects, and that I hope
this notice will serve to draw attention more generally to
their construction and use.

239

TRANSLATIONS.

Notice of the OccurreNcr of a NEMATOID Parasite in the
Ovum of Limax griseus. By M. A. Barruitemy.

(From the ‘ Comptes rendus,’ Jan. 24th, 1859.)

In studying the development of Limax griseus, I was not
a little surprised to discover in the first ovum submitted to
microscopic examination a minute Nematoid worm, in which
might still be observed some vitelline granules. In other
ova, more advanced in development, I have noticed similar
vermicules, often to the number of three or four, and which
had apparently undergone a development corresponding to
that of the creature whose domicile they had invaded. At
this stage they were large enough to be readily seen with a
simple lens, performing tolerably active movements. In most
cases they remain at some distance from the embryo, though
occasionally I have noticed one of them attached to the
vesicle which surmounts the head of the future mollusc.
Lastly, in some ova still further advanced, the parasite had
destroyed its host, the walls of the ovum were collapsed, and
the Nematoid worms might be observed in the interior
arrived at their full development—that is to say, furnished
with the reproductive organs.

The transparency of the worm renders a precise knowledge
of its anatomical constitution easily attainable by simple
microscopic examination. Its conformation appears to me to
remove this worm so far from all known types, as to autho-
rise the establishment for its reception of a new genus, for
which I propose the name Ascaroides. The species I propose
to term A. limacis.

In the first place, I had to investigate the mode of origin
of the worm. The presence of this animalcule within an
ovum, to all appearance so efficiently protected against such
Invasions, was an embarrassing fact. Having ascertained,
by direct experiments, that the worm is present in the ovum
at the time of oviposition, I subjected to anatomical inspec-
tion under the microscope those slugs whose ova were thus
infested. In several of these, I found in the alimentary canal
and in the ovaries the parasitic vermicule still distended with
vitelline granules, and always accompanied by a very minute
monadiform Infusorium. I have seen and drawn two of
these vermicules already installed in the ova in process of
formation, and have thus discovered the complete vital cycle
of the new parasite.

240

On the Measurement of the Vertican Tuickness of
Microscopic Ossects ; and on the DETERMINATION of the
Cuemicat Propertiss from their REFRACTIVE Powrr. By
Dr. H. Wetcxer, of Giessen.

In the ‘ Zeitschrift f. Rat. Medicin,’ N. F., vi, p. 172, and
vill, p. 241, the author endeavoured to show, that when
by a methodical raismg or depression of the tube of the
microscope the relief of microscopic objects has been ascer-
tained,—the question, especially as respects the more difficult
class of objects, may be decided, as to whether they are
hollow or solid, depressed or convex. If a microscopic
object be of such a size as to allow of its near and distant
surfaces being each distinctly and separately brought *into
view by the proper adjustment of the tube of the instrument,
the determination of this question is usually unattended with
any difficulty ; the proceeding, in fact, beg one commonly
practised. The author, however, has endeavoured to show,
that in the smaller or even in the most minute microscopic
formations—so small even that they appear only as simple
dark points—a bright flash or gleam ensues upon the eleva-
tion of the tube, in those cases that is to say in which the
bodies in question are convex; and a similar flash on the
depression of the tube, when they are concave. “I have
shown,” he says, “that in the former case the convex
corpuscles act like minute convex lenses, and in the latter
like concave lenses. Oil-drops contained in water or air,
albuminous and many other sorts of particles,—in short, all
such as in regard to their optical property are referable to
the perfectly spheroidal form, show the brilhant appearance
on the elevation of the tube; whilst minute air-bubbles, the
cavities in bone, teeth, &c., containing air or fluid, &e., pre-
sent the same phenomenon when the tube is lowered.

Since in by far the greater number of cases the fluids of
the animal or vegetable organism have less refractive power
than the solid constituents suspended in them, or which, on.
the other hand, may lodge the fluids in question in internal
cavities, it is apparent as a rule that when an object exhibits
its utmost briliancy on the elevation of the tube, a con-
vexity must exist; and again, that it must be concave when.
the brilliancy is witnessed on the depression of the tube.
But I haye lastly remarked, that for the determination of the:
relief of a microscopic object it is of essential importance:
also to regard the refractive property of the surrounding
medium. For under certain circumstances, even perfectly

WELCKER, ON MICROSCOPIC MEASUREMENTS. 241

spheroidal bodies or convex solid corpuscles—as, for instance,
a particle of glass—may exhibit the brilliancy on the depres-
sion of the tube when such bodies are contained in a medium
possessing stronger refractive power than themselves. Thus
particles of glass contained in oil of aniseed, appear brilliant
on the depression of the tube, exhibiting, in fact, precisely
the same optical conditions as a cavity in glass or an air-
bubble in water.

The following observations are intended to point out the
further applicability of a methodical elevation or depression of
the object-glass.

1. Measurement of the vertical diameter of microscopic
objects.

The idea readily suggests itself, that the height of micro-
scopic objects may be estimated under the microscope by the
determination of the distance passed through by the object-
glass, when focussed on the apex and base of the object.
When the value of a turn of the screw of the fine-adjustment
is known, and can be estimated by proper graduation of the
head of the screw, it is very easy to determine how much
the tube has been raised or depressed in this operation.
This mode of determining the altitudinal diameter is given
by Harting,* and several authors have stated the values of
vertical diameters obtained in this way. But the vertical
diameter of microscopic objects cannot be thus immediately
determined by the amount of movement of the tube, which
movement gives us the vertical diameter of the object, as
affected by the difference between the refractive power of the
air and that of the object under view.

The correctness of this statement is obvious, from the
simple consideration, as first pointed out by V. Mohl,+ that
the rays of hght proceeding from an object covered with
glass enter the objective in a different direction, and
consequently require a different (more elevated) position of
the tube, than do those of an uncovered object. When
layers of equal thickness of various highly refracting
substances are examined, it will be found that the distance
traversed by the tube when adjusted to the upper and lower
surfaces respectively, is less in proportion to the greater
refractibility of the substance examined. The length of
‘movement. of the tube, therefore, employed immediately as a
measure of the vertical thickness, would lead to an under-

* ©Das Mikroskop.’—Germ. Transl.
+ ‘Mikrographie,’ p. 159.

242 WELCKER, ON MICROSCOPIC MEASUREMENTS.

estimation of it in proportion to the degree in which the
refractive power of the substance exceeded that of the air.*

I give, in the first place, a very generally applicable method
of determining the refractive power, or of the “ apparent
height” of microscopic objects, together with some numbers
by which, from the “apparent height” thus determined, the
“true height” of the object may be calculated.

If the microscope, like the instruments of Kellner, Belthle,
Oberhauser, &c., is furnished with a fine-adjustment screw,
having a horizontal head, this will be readily made into a
micrometer, by marking off each fifth or tenth groove on its
edge by a fine line, to be numbered accordingly. The index
may be formed by a small point suspended from any fixed
part of the microscope immediately above the screw-head, and
just touching it. Lastly, the value of a turn of the screw is
ascertained, as well as of parts of a turn.t

In my microscope, made by Kellner, whose screw-head is
accurately divided at the edge into 205 parts, I obtained the
following figures :

30 turns of the screw depress the tube about 11‘Omm.
1 turn consequently = 0°3667mm.
1 notch at the edge (=z3, turn) = 0°0018mm. ”

By means of the screw of this microscope I then estimated
the refractive power of numerous substances, selecting in
fact, for the purpose, the most important. fluids and trans-
parent tissues of the animal body, as well as some of the
substances used in the examination and preservation of mi-
croscopic objects.

Two narrow strips of glass, not quite 1mm. thick, were
glued upon the object-bearer, a few millimetres apart, and
upon these was laid thin covering glass. The two glass slips
inclosed between them a stratum of air, whose thickness,
by accurate measurement, was found to be 0°9873mm.
On the under surface of the covering glass, as well as on the
upper surface of the object-bearer, very fine lines were
scratched with a diamond ; the upper ones in a vertical, and
the under in a horizontal direction. The accurate micro-
scopic definition of these two sets of lines required a move-
ment of the tube corresponding to two turns of the screw
and 142 notches, in all 552 notches.t When the stratum

* This wxder-value, according to the author’s investigations, amounts, in
substances possessing slight refractive power, to about one third, and in
those of very considerable power to nearly one half of the true value.

+ It is scarcely necessary, perhaps, to remark that a properly divided
screw-head accompanies the fine-adjustment of most English microscopes.

+ In all cases the upper set of lines were first viewed, and then, by a

WELCKER, ON MICROSCOPIC MEASUREMENTS. 243

of air was replaced by a fluid,—for instance, by glycerine
introduced between the two plates of glass—the accurate de-
finition of the two surfaces now required a movement of the
tube corresponding to 372 notches. The real thickness,
therefore, of the layer of glycerine, was to the apparent
thickness as 552 to 372, or as 148 to 100. To ensure cor-
rectness, I prepared a second glass cell, within which the
stratum of air measured 1002 notches, and that of glycerine
678,—7. e., in the same proportion to each other of 148 to
100. The fluids enumerated in the following collection were
all proved in this double way. The refractive power of solid
substances was estimated in a similar manner,—that is to say,
by measuring the apparent thickness of a section compared
with the thickness of a stratum of air of the same actual
thickness.

TABLE,
Showing the ¢rwe thickness of various substances whose apparent thick-
ness = 100.

pA nee A : ; : . 100
Distilled water . : : : . 138
Spring water : 4 : : == Tos
Human blood-serum : : oy 139
Albumen of Hen’s egg (fresh) , ‘ #2189
Blood-serum of Lacerta muralis « A LAO
Human corpus vitreum (eighteen hours after death) . 140
Sulphuric ether. : : : 24d
Alcohol, 87° : : af ; . 142
Recent muscle of frog > : : . 1426
Water-glass of Batka (fluid) . 145
Mucilage of gum (1 centigram. water ; ; 0-5 gramm, gum-

arabic) : : : : . 147
Glycerine . 148
Thicker mucilage. of gum a centigram, water 5 1 gramm.

gum-arabic) . «yl
Water-glass of Batka (dry) . J an JDO
Marrow (knochenfett) blenclied i in the sun : «1 bel
Oil of turpentine . : : : >. au
Oil of lemons ; : : : ~ 1515
Human fat : : : ; a Lb?
Rape oil : : : » 152°5
Canada balsam (fresh) é , , « Lb4°5
Common crown glass ; : : 155, 156
Copal varnish (fresh) : : : 22156
Oil of aniseed : , : . 158
Dry albumen : ’ Q : - 165
Gelatine (dry). . : : » 70
Bone . ; é : : ee
Ivory . ; : b pl lits
Enamel of Horse’s tooth : : ae |

downward rnovement of the screw, the under ones ; because if the contrary
direction had been followed, the spiral elevating spring might possibly not
be exerted uniformly, and a dead turn of the screw-head be made,

244 WELCKER, ON MICROSCOPIC MEASUREMENTS.

From these figures the true thickness of numerous objects
may be readily estimated from the apparent thickness as
shown by the focussing of the tube.

The conditions of bodies having even horizontal surfaces
present the problem in its simplest form, and bodies of this
kind may in the first place be considered. For instance, an
albuminous investing layer of a microscopic object requires
for the definition of its upper and under surfaces a movement
equal to 12 notches. For albumen the above table gives the
number 139. Consequently we have 100:139 = 12:2, and
obtain the value of 16°6 notches, that is to say (according to
the value of the division of the screw-head given above),
0:0297 mm. as the thickness of the investing layer, whose
apparent thickness (12 notches) would be 0°0215 mm.

In this way I have several times estimated the thickness
of horizontal layers in cases where the preparation of verti-
cal sections and the common mode of measurement were
inapplicable.

If it be asked what is the certainty of the above method, and
to what extent it is applicable, it should be remarked that the
certainty of the optical focussing is far greater than it would
at first sight appear to be. The movement of the tube, in de-
fining the upper and under surfaces of a very thin lamella
may amount to less than a notch ; but it will be pretty nearly
the same in repetitions of the experiment. In the hands of
any one practised in the. precise definition of microscopic
objects, the results do not readily vary more than a half per
cent. The uncertainty of the method, however, diminishes
in proportion to the minuteness of the objects. In the ease
of a stratum of albumen of the same density as the saliva,
the depression of the tube amounts to 1:5 to 2°5 notches, as
may be ascertained with sufficient certainty, and for which
apparent thicknesses, instead of 0°0027—0:0045 mm. may
be properly substituted 0:00837—0:0062 mm. If the thick-
ness to be measured be less than that of a human blood-cor-
puscle (00020 mm.), the movement is so little, and the num-
bers denoting the apparent and the true thickness so nearly
the same, that the method (at any rate with the common
magnifying powers and the simple apparatus here described)
appears to be no longer applicable.

If the refractive power of a body, whose thickness it is
sought to determine, is not contained in our Table, an
approximate estimate of it is always possible.

This arises from the circumstance, that from the optical
relation which the body in question exhibits with respect to
the medium surrounding it, and whose’ refractive power is

WELCKER, ON MICROSCOPIC MEASUREMENTS. 245

known, it may be deduced whether the apparent thickness of
the body under examination should be corrected to the
refractive power of aqueous media (100—142), fluid fat
(100—150), or the most strongly refractive substances (100
—160—180). If a substance (e.g. glass) lying in Canada
balsam exhibit the bright spot when the tube is elevated, and
in oil of aniseed when it is depressed, it may at once be con-
cluded that the refractive power of the body lies between
154 and 158.*

In the case of a spherical or cylindrical body, it is obvious
that the determination of the horizontal diameter by com-
mon linear measurement will be preferred to the estimation
of the vertical thickness. But the question is different when
it is doubtful whether the figure be really spherical or cylin-
drical, or not rather of some other rounded form.t In the
determination of the vertical diameter, which (if the object
does not admit of rotation) may in cases of this kind be
desirable, it is assumed that the refractive power of the
surrounding medium is known.

In the experiments above detailed, in which the object was
a horizontal plate, the objective, when focussed upon the two
surfaces, travelled in one and the same direction, dependent
upon the thickness and refractive power of the particular
object, and communicated one and the same thickness, whe-
ther the object were placed in air and exhibited a great
degree of briliiancy, or in oil and wholly without any. If
the object, however, be a sphere (and precisely analogous
phenomena are exhibited im other bodies having rounded
surfaces) the microscope will afford a view of the upper and
of the lower surfaces only when the refractive power of the
object and that of the surrounding medium are equal or
nearly so. When the object possesses a considerably greater
refractive power than the surrounding medium, the focussing
of the objective will afford, not the “ optical transverse dia-

* Conclusions of this kind are inadmissible when the surrounding fluid
exerts any kind of chemical or physical influence upon the object of such a
kind as may alter its refractive power. Thus, in glycerine the striped mus-
cular fibre shows brightness on the elevation of the tube, because its refrac-
tive power is increased (probably by imbibition of water), and it thus appears
to possess a stronger refractive power than glycerine. But the refractive
power of unaltered muscular fibre is by no means higher than that of gly-
cerine, but far less, being little greater than that of blood-serum.

+ With respect to this, it is well known that our vision may be deceived
in very many ways by refraction. Thus, in the case of perfectly cylindrical
objects, the appearance of flattening is always produced when the refractive
power of the surrounding medium is but little less than that of the inclosed

object. Thus a cylindrical thread of glass in Canada balsam appears’ as a
flattened band-like streak of little brilliancy.

246 WELCKER, ON MICROSCOPIC MEASUREMEN'S.

meter,” as it is said, more particularly in such instances, by
the majority of authors, to do, but only of that part of the
spherical surface which lies above the equator; the under
hemisphere exhibiting only very faint images. If the object
possess less refractive power, or be a hollow sphere, the optical
focussing reaches only the lower half of the hollow sphere.
If the distance traversed in the focussing of the objective
between the apex (or base) and the equator be now mea-~
sured, we obtain a reciprocal value according to the quality
of the surrounding medium. We measure, in fact, the
apparent depth of a layer of the surrounding medium, which,
corrected for its true depth, is nearly equivalent to the semi-
diameter of the sphere. In exactly the same way, in the
case of rounded objects not of a spherical figure, the focus-
sing of the objective embraces that part of the surface of the
object which rises above the greatest horizontal section,
when that portion of the object refracts the light lke a
convex lens, and the under portion when it acts like a concave
lens. In this case the movement of the tube bearing the
objective corresponds to the apparent thickness of a stratum
of the surrounding substance, whose true thickness is nearly
equal to the height of the rotundity to be measured.

2. The determination of the chemical quality of micro-
scopic objects from their refractive power.

The optical relations of objects have hitherto been em-
ployed only to a very limited extent as a means of diagnosis
in microscopic researches. Leaving out of account the
application of the polarizing apparatus, observers have hitherto
confined themselves almost entirely to speaking of the greater
or less refractive powers of objects according to the greater or
less brilliancy of the light proceeding from them. But not
only is this mode of description in itself vague, but in addi-
tion, so long as the refractive power is estimated simply
from the impression made upon our eyes by the object—
that is to say, from its greater or less brilliancy—our judg-
ment is exposed to great deceptions. For, as has been shown
above, it depends wholly and solely upon the refractive
power of the medium surrounding the body under investiga-
tion, whether the refractive power of the body can be esti-
mated from the phenomenon of its brilliancy or not. Thus
in the case of microscopic fatty particles, the strong bril-
lianey of the fat affords one of the most useful means of
recognition; but it must be remembered, that fat injected
into the canaliculi of a bone, owing to the greater refractive
power of the bone, does not exhibit its usual brilliancy.

WELCKER, ON MICROSCOPIC MEASUREMENTS. 247

It occasionally happens in microscopic investigations, that
minute morphological elements of unknown chemical nature
occur within a tissue, but which are too minute or too
difficult of isolation to be subjected to chemical analysis. May
it not, in such a case, when the “ true” and the “ apparent’
thickness of the corpuscles are known, perhaps be possible
to arrive at some conclusion as to their chemical constitu-
tion? Let us, by way of example, take a case in which it is
doubtful whether an inclosed corpuscle be albuminous or fatty.
Let the apparent thickness of the corpuscle = 0:0030 mm.,
and the true thickness (ascertained by common measure-
ment of it in profile) = 0°:0042mm. The object in this case
cannot be fat,—for in fat the true diameter stands to the
apparent in the proportion of 0:0045 to 0°0030. But this
ascertained refractive power would correspond with that of
albumen (0:0030 : 0:0042 = 100: 140).

But, although considerations of this kind maylead to the pro-
spect of a new, and not altogether useless method of diagnosis,
its application will be found to be much limited by the fol-
lowing conditions. In the first place, the method would
become more and more uncertain, and ultimately wholly
useless, in proportion to the greater minuteness of the ob-
jects. And, also, when the object has rounded sur-
faces, it is not, for the reasons already adduced, at all
adapted to determine the refractive power or the apparent
thickness of the object.

From the above exposition, I am by no means of opinion
the mode of measuring by the vertical movement of the tube
of the microscope, for either of the purposes proposed, is
capable of any extensive application. My object has rather
been to test the applicability of such a mode of measurement
in the general method, and to establish it in some particular,
may be rare instances.

248

REVIEWS.

Evenings at the Microscope ; or, Researches among the Minuter
Organs and Forms of Animal Life. By Puiir Henry
Gosss, F.R.S. London: Society for Promoting Christian
Knowledge.

Ir is always a pleasant thing to meet Mr. Gosse in print,
whether he ushers himself into the world from the Red Lion
press in Paternoster Row, or obtains the sanction of “ the
Committee of General Literature and Education appointed
by the Society for Promoting Christian Knowledge.” Why
Mr. Gosse publishes his books under the direction of a
Society for promoting Christian knowledge at all we are at
a loss to perceive, for we find nothing in this book that
might not have been published by Mr. Van Voorst, or the
most sceptical publisher in the Row. We are, in fact, a
little jealous of religious societies publishing books of this
sort, both on the grounds that such. books are not strictly
Christian, and that funds are appropriated to their produc-
tion to the injury of the regular publisher which were not
intended for this object. It is true that this does not in any
way interfere with the quality of the work, and this iswith what
we have more particularly to do. As its name would imply,
Mr. Gosse’s book is a popular introduction to working with
the microscope. It differs, however, from other introduc-
tions to the microscope, that it contains no account of the
structure of the microscope at all. This is really a feature,
albeit a negative one, in the book. As reviewers bound to
read every word of every book we notice, we are glad for
once to deal with one on the microscope without anything
about the microscope at all.

Turning to Mr. Gosse’s work, and conscientious re-
viewers as we are, we miss a chapter of contents which
would be particularly useful to us just now; we find
that he treats of the usual objects examined under the
microscope. He begins with human hairs, and _ this
naturally enough brings him to hogs’ bristles and cats’
hairs. From hairs we proceed in morphological order
to the feathers of birds and the scales of fishes. Here
we are arrested, not in any scientific or consecutive order, by a
chapter on the blood. Then come the shells of mollusca,
with descriptions of the tongues, teeth, and eyes of the same

GOSSE, ON THE MICROSCOPE. 249

animals. From these we are taken to a general survey of
the structure of insects, with interesting dissertations on the
functions of their microscopical organs. All this time we
feel the author is doing himself violence. He longs to get to
the sea-shore. There he has used his microscope with most
success, and on the microscopic objects of the sea he dwells
with more than usual wonder and eloquence. Crabs, the
structure and transformation of Crabs, Sea-acorns and
Barnacles, the hooks of Serpula, the movements of Pedicel-
lariz, the spines of Echini, the anchors of Synapta, and the
transparent wonders of Sarsia, Thaumantias, Cydippe, and
Turris, all pass before us. Polypes and sponges finish the
history of sea-animals, and the volume closes with accounts
of infusory animalcules. Such isa brief outline of Mr. Gosse’s
book. ‘To say there is nothmg new in it would be wrong,
for Mr. Gosse always looks at things for himself, and the
Gossean view is frequently a new one.

But it is for no scientific novelty that this work will be
valued. Mr. Gosse is a writer, and a very agreeable one
too, and im all this work he succeeds in throwing a charm
over his subject which can but lead his reader on, whether
they ever looked into a microscope or not. We shall not,
therefore, transfer to our pages any of his more technical
descriptions of microscopic objects, but give one or two pas-
sages to illustrate the style of the book. His chapters are
more like lecturettes or demonstrations than anything else.
We may fancy him sitting at a table with his microscope
before him, and discoursing quite at his ease to a few
friends invited expressly to hear what he has to say. The
party being seated, he thus begins:

“Not many years ago an eminent microscopist received a communication
inquiring whether, if a minute portion of dried skin were submitted to him,
he could determine it to be Awman skin or not. He replied that he thought
he could. Accordingly a very minute fragment was forwarded to him,
somewhat resembling what might be torn from the surface of an old trunk,
with all the hair rubbed off.

“The professor brought his microscope to bear upon it, and presently
found some fine hairs scattered over the surface ; after carefully examining
which, he pronounced with confidence that they were Auman hairs, and such
as grew on the naked parts of the body; and still further, that the person
who had owned them was of a fair complexion.

“This was a very interesting decision, because the fragment of skin was
taken from the door of an old church in Yorkshire ;* in the vicinity of which

* “T am writing from memory, having no means of referring to the original
record, which will be found in the first (or second) volume of the ‘ Transac-
tions of the Microscopical Society of London.’ The general facts, however,
may be depended on,” a

250 GOSSE, ON THE MICROSCOPE.

a tradition is preserved, that about a thousand years ago a Danish robber
had violated this church, and having been taken, was condemned to be
flayed, and his skin nailed to the church door, as a terror to evil-doers. The
action of the weather and other causes had long ago removed all traces of
the stretched and dried skin, except that from under the edges of the broad-
headed nails, with which the door was studded, fragments still peeped out.
It was one of these atoms, obtained by drawing one of the old nails, that
was subjected to microscopical scrutiny; and it was interesting to find that
the wonder-showing tube could contirm the tradition with the utmost cer-
tainty ; not only in the general fact, that it was really the skin of man, but
in the special one of the race to which that man belonged, yiz., one with
fair complexion and light hair, such as the Danes are well known to possess.
‘Tt is evident from this anecdote that the human hair presents characters
so indelible that centuries of exposure have not availed to obliterate them,
and which readily distinguish it from the hair of any other creature. Let
us then begin our evening’s entertainment by an examination of a human
hair, aud a comparison of it with that which belongs to various animals.”

Thus pleasantly does the author lead us on to the structure
of a hair from his own head—we are afraid it is getting
grey,—and from this to all other hairs. At his next sitting
he takes up the blood, and thus prepares us for an interest in
this important fluid :

‘The microscope is daily becoming a more and more important aid to
legal investigation. An illustration of this occurred not long ago, in which
a murder was brought home to the criminal by means of this instrument.
Much circumstantial evidence had been adduced against him, among which
was the fact, that a knife in his possession was smeared with blood, which
had dried both on the blade and on the handle. ‘The prisoner strove to turn
aside the force of this circumstance by asserting that he had cut some raw
beef with the knife and had omitted to wipe it.

“The knife was submitted to an eminent professor of microscopy, who
immediately discovered the following facts:—1l. The stain was certainly
blood. 2. It was not the blood of a piece of dead flesh, but that of a
living body; for it had coagulated where it was found. 3. It was not the
blood of an ox, sheep, or hog. 4. It was human blood. Besides these
facts, however, other important ones were revealed by the same mode of
investigation. 5. Among the blood were found some vegetable fibres.
6. These were proved to be cotéon fibres,—agreeing with those of the mur-
dered man’s shirt and neck-kerchief. 7. There were present also numerous
tesselated epithelial cells. In order to understand the meaning and the
bearing of this last fact, I must explain that the whole of the internal sur-
face of the body is lined with a delicate membrane (a continuation of the
external skin), which discharges mucus, and is hence termed mucous mem-
brane. Now this is composed of loose ceils, which very easily separate,
called epithelial cells ; they are in fact constantly in process of being de-
tached (in which state they constitute the mucus), and of being replaced
from the tissues beneath. Now microscopical anatomists have learned that
these epithelial scales or cells, which are so minute as to be undiscernible
by the unaided eye, differ in appearance and arrangement in different parts
of the body. Thus, those which line the gullet and the lower part of the
throat are ¢esselated, or resemble the stones of a pavement; those that
cover the root of the tongue are arranged in cylinders or tall cones, and
are known as co/ummar; while those that line some of the viscera of the’

PRESCOTT, ON TOBACCO. 251

abdomen carry little waving hairs (ci/éa) at their tips, and are known as
ciliated epithelium.

“The result of the investigation left no doubt remaining that with that
knife the ¢hroat of a living human being, which throat had been protected
by some coéfoz fabric, had been cut. The accumulation of evidence was
fatal to the prisoner, who without the microscopic testimony might have

escaped.
* But what was there in the dried brown stain that determined it to be
blood? And, particularly, how was it proved not to be the blood of an ox,

as the prisoner averred? ‘To these points we will now give a moment’s
attention.”

_ We might add a large number of extracts such as these,
but enough has been given to show the way in which Mr.
Gosse treats his subject. The work is copiously illustrated
with woodcuts, the majority of which are from Mr. Gosse’s
own drawings. The woodcuts are perhaps a little coarse,
but they appear to be faithful representations of the objects
described. We can recommend Mr. Gosse’s book as a very
pleasant companion to the microscope.

Tobacco and its Adulterations. With illustrations, drawn and
etched by Henry P. Prescott, of the Inland Revenue
Department. London: Van Voorst.

Many substances used for the adulteration of articles of
commerce, which formerly defied all kinds of investigation,
are now easily discovered by the aid of the microscope. The
medical man was the first to apply this instrument in the
detection of fraudulent adulterations of food and medicine.
The Government has been slow to appreciate its use in the
cases where it might have been employed to detect fraud on
taxed articles of consumption. We are, however, glad to
be able to congratulate the Inland Revenue department on
the possession of an officer who is so capable of appreciating
the value of microscopic aid in the detection of adulterations
as Mr. Prescott appears to be. It has been long known
that chemistry is of little service in detecting the adulteration
of tobacco. In fact, for many years, it seems, that instead
of chemistry detecting frauds in the adulteration of tobacco,
it was the unintentional source of fraud by the Government,
who fined tobacconists for having tobacco in their possession
which contained sugar, when it afterwards turned out that
all tobacco naturally contains a certain quantity of sugar.

VOL. VIT. ¥

252 PRESCOTT, ON TOBACCO.

Dr. Hassall, in his report on the adulterations of tobacco,
says that he could not discover, in forty specimens of
tobacco he had examined, the admixture of any foreign leaf.
Mr. Prescott, however, states, that from time to time there
have been discovered with the leaf of the genuine “ weed,”
the leaves of rhubarb, dock, burdock, coltsfoot, beech,
plantain, oak, and elm. Also peat, earth, bran, saw-dust,
malt-worts, barley-meal, oatmeal, bean-meal, pea-meal,
potato-starch, and chicory leaves steeped in tar-oil. Now
this is a list that would surely arrest the most inveterate
smoker in his course, provided he was not assured that, by
the aid of the microscope, all these substances may be
detected. This is the object of Mr. Prescott’s book ; not to
enable smokers to detect adulterated tobacco, but to enable
Government officers to prevent the sale of adulterated
tobaccos to smokers at all. In order to do this, Mr. Prescott
thinks that two things are necessary; first, that Government
officers should know what leaves are; and second, that they
should know what a microscope is. So that his book is not
so much an account of tobacco, as it is of the things with
which it is adulterated, and the instrument by means of
which they are detected. It is somewhat humiliating to
find that people who have been to school within the last
twenty-five years should have to be taught what leaves are,
and what a microscope is; but such is the fact, and very
thankful such people ought to be to those who write for
their instruction and benefit. But Mr. Prescott has not
only written on these elementary subjects, but he has given
in this work a series of original researches upon the structure
of the tobacco leaf, and the leaves of several other plants,
very useful for the Inland department, and highly interest-
ing to all engaged in botanical pursuits. He has very
modestly put his observations into the form of illustrations
of the objects investigated, with descriptions of the plates.
He first describes, minutely, the structure of the tobacco
leaf, giving its tissues, vascular and cellular, their distribu-
tion in the petiole, the ribs, and the blade. The epidermis
and its appendages are especially described, and it is on
this point that Mr. Prescott dwells as affording the greatest
amount of evidence in judging of the purity of specimens of
tobacco.

Of course, all our microscopic friends who smoke know
that the hair of the tobacco leaf is a knobbed hair. Three
or four long cells grow up straight from the epidermis, and at
the end of these is a compound cell, composed of five or six
cellules. Such a hair does not seem to occur in any other

PRESCOTT, ON TOBACCO. 253

plant. Now, if in the examination of a particular specimen,
any other kind of hair occurs than this identical mace-like
hair, then it may be at once concluded that the tobacco has
been adulterated. But adulterated with what? That is the
next question to which Mr. Prescott addresses himself. A
large series of the leaves of plants are examined for the pur-
pose of showing the forms and nature of their hairs. Not
only are those plants described which are used for the adultera-
tion of tobacco, but many others. Mr. Prescott feels that he
has struck upon a vein that will reward the working, and with
perhaps more love for science than regard for the revenue, he
gives us a series of descriptions of the hairs of other plants than
are used by fraudulent tobacconists. In this work will be
found beautiful and truthful delineations of the epidermis and
hairs of the thorn-apple, the potato, the dandelion, the sun-
flower, the elecampane, the comfrey, the foxglove, the mullein,
the hellebore, and the plantain, besides those employed for
adulterating tobacco. He has also given representations of
the starches contained in these plants, so that should the hairs
fail, the form of the starch itself may in some cases lead to
the detection of adulteration.

Whilst going over Mr. Prescott’s book, we have been
struck with the fact that a closer attention than has yet
been generally given, to what might be termed the special
microscopic characters of plants, would be advisable, and
likely to prove advantageous in diagnosis. Mr. Prescott’s
observations, for instance, on the “ Hairs of Plants,” will
suffice to show what may readily be done in this direction.
The subject, at any rate, is one deserving of notice by
younger microscopical observers who may be in want of a
subject, and to them we cordially recommend the present
volume.

NOTES AND CORRESPONDENCE.

Bermuda Tripoli—tThis material is in great request among
students of Diatomaceze, but its history requires to be cleared
up. The general belief is that it was obtained from the
Bermudas, and Ehrenberg states this in express terms; his
sample, however, was received from the late Dr. Bailey,
who himself speaks more cautiously. He mentions, in
his account of this deposit, in ‘Silliman’s Journal,’ vol.
xlviui, that he had received it from Mr. Tuomey; and that
Mr. Tuomey had obtained it from a mimeral collector, as
tripol, from Bermuda; but Dr. Bailey states that this
tripol is not calcareous, whereas other fossil remains oc-
curring in Bermuda Islands contain abundance of calcareous
Polythalamia. He, therefore, when he distributed portions
of the sample, added “locality doubtful.’ Although some
of the diatoms in this deposit are peculiar to it, there are
others which occur also in the Virginian and Maryland earths,
a circumstance which indicates that 1t was more probably col-
lected in the United States. The Richmond deposit, in-
cluding that from Schuckoe Hill (on which part of the city
of Richmond is built), is well known to be very extensive.
Petersburgh, about twenty-six miles to the south, also yields
diatomaceous earth scarcely differing from that of Richmond.
Both these are elevated several feet above the level of the sea,
although the earth be full of marine productions.

On the north bank of the James River, where it begins to
widen into an estuary or bay, is the plantation or “ hundred ”
called Bermuda, about twenty miles below Richmond. It
seems perfectly clear that, although unknown to Dr. Bailey,
this is the place from whence the mineral collector had re-
ceived the tripoli. The deposit may be more recent than
those of Richmond and Petersburgh; and, if so, all the
species of Heliopelta, for which it is celebrated, may yet be
found recent along the shores of the estuary. The Bermuda
in Virginia appears, then, to be the Bermuda of Diatomists,
and is situated nearly in N. Lat. 37° 18’, and W. Long.
76° 26’. The confusion seems to have arisen from Long
Island, one of the Bermudas or Somer’s Islands, being
also sometimes called Bermuda.—G. A. Warxker-ARNOTT?T,
Glasgow. )

MEMORANDA. 255

The Diagonal Scale.—Among the greatly increased and
continually increasing number of microscopists, there may be
some to whom remarks even of a somewhat elementary cha-
racter may be acceptable. To such I would offer some sug-
gestions on what, from my own experience, I conceive to be a
very great desideratum. ‘This is a more extended know ledge
of and practical agreement in microscopical mensuration.

The various quantities used in defining the magnifying
powers of lenses, as well as in speaking of the magnitude
of images of objects, are to the uninitiated somewhat perplex-
ing; but when the mind is trained to a just appreciation of
standard measures, a moment’s consideration clears up what
otherwise presents an apparently mystical and indeterminate
aspect.

On this account I would suggest to microscopists the general
use of the diagonal scale, that is, of a scale of 12 inches,
with the terminal inch divided both ways (ends and sides),
the vertical lines being diagonal—a common Gunter’s scale
at once provides the requirement. Why I suggest one
of 12 inches is because it is portable and supplies a measure
also for the determination of a 10-inch or other elevation in
using the camera, Se.

The inch being usually divided into 100th or 1000ths, I
shall refer to these as the 100th or 1000th scales.

If, therefore, the 100th scale is implied, the numbers on
the line a B will indicate the parts of a hundred in tens for each
line, and the numbers on the line Bc will indicate units.
Thus, supposing I wished to know the exact measure of a mag-
nifying power of 95, by placing one leg of the compass on the
point a, and extending the other to the figure 9 on line aB,
the space equals 90; then, by following down the lines dia-
gonally towards c, until opposite the figure 5 on the unit
line, I have a standard measure corresponding to a power of
95. Every deviation from this must be accounted erroneous.

If, again, I wished to know the measure of space on the
1000th scale of a magnifying power of 450; then, what were
before considered tens and units are now regarded 100ths
and tens; thus, from the point a, to figure 4 on the line a B,
equals 400, andi as in the former example, the distance on the
diagonal to opposite the figure 5 on line Bc, equals 50, or
450, the measure required.

It will also frequently occur, that ten times this quantity
may be needed, or ten spaces of 1000 inch scale, magni-
fied in the same ratio; then, taking as above 450, add a
cipher making 4500,—the 4 will then indicate clear inches ;
the 5 on line 4B will equal hundreds; and, if tens are wanted,

256 MEMORANDA.

they will correspond to some figure on line pc, being now
tens of the 1000 scale, as they were units of the 100 scale.
Thus have we a ready means of fulfilling several important
requirements ; first, of measuring the elevation for the camera ;
secondly, of accommodating or adjusting one power with
another; thirdly, of proving the reputed powers of different

lenses ; fourthly, of proving the precision of micrometers ;
fifthly, of drawing the images of objects in exact numerical
terms; and lastly, of detecting errors of observation.

The accompanying scale is only half the size of that re-
quired. Gunter’s scale represents a fullinch.— Wn. Henpry,
Surgeon, Hull.

Angular Aperture.—I beg to submit an account of a simple
method by which any one may easily measure the angular
aperture of his object-glasses. I can hardly suppose it is
original; but as I have met with no account of it, and as it
dispenses with the use of the protractor, and of the appa-
ratus described in the books for the purpose (without which
some, I know, are not aware that the object in view can be
effected), I venture to send it, in the hope that it may be of
use.

Place the microscope horizontally, with the eye-piece
removed, and the object-glass attached whose aperture is to
be measured. On a line (which may be conveniently in-
dicated by a piece of string stretched across the table on
which the microscope stands) at any moderate distance from
the object-glass, and at right angles to the axis of the in-
strument produced, place two candles, having their fiames, as
nearly as may be (which may be easily managed by the aid
of a few books), on a level with the axis of the instrument.
Now, with the eye applied to the ocular end of the micro-
scope, make an assistant slowly move first one candle and
then the other along the line on which they are placed, till
the images of the two flames are just seen at opposite edges
of the object-glass. Measure carefully, with a bit of string,
first the distance between the two flames, and secondly the
distance from the object-glass of the line joining them. The

MEMORANDA. 257.

former of these distances divided by twice the latter will
give the tangent of half the angle of aperture. The angle
corresponding to this tangent, therefore, being found by the
aid of the ordinary trigonometrical tables, the double of it
will be the angle required.

Thus, with an excellent quarter by Ross, I find the dis-
tances between the flames 214 inches, and the distance of
the line joining them from the object-glass 123 inches.
Hence, dividing 21:5 by 24°5, I obtain 8775, which I find
to be the natural tangent of 41° 16’; consequently the angular
aperture is 824 degrees.—P. Gray, 7, St. Paul’s Villas,
Camden Town.

Glycerine Jelly.—In most of the works on the microscope,
gelatine is mentioned as a medium for the mounting of certain
objects, and several mixtures of gelatine with other sub-
stances have been suggested, but none of these have suc-
ceeded so well in my hands as the following, which I am
induced to publish, because all my friends to whom I have
communicated it have tried and approved it.

It is the only medium which will preserve the natural
colour of vegetable substances.

The beautiful green of some mosses, I mounted two years
ago, is still as fresh as on the day they were gathered.

My formula is as follows:

Take any quantity of Nelson’s gelatine, and let it soak
for two or three hours in cold water—pour off the super-
fluous water, and heat the soaked gelatine until melted. To
each fluid ounce of the gelatine add one drachm of alcohol,
and mix well; then add a fluid drachm of the white of an
egg. Mix well (whilst the gelatine is fluid, but cool). Now
boil, ‘until the albumen coagulates, and the gelatine is quite
clear.

Filter, through fine flannel, and, to each fluid ounce of the
clarified gelatine, add six fluid drachms of Price’s pure
glycerine, and mix well.

The objects intended to be mounted in this medium are
best prepared by being immersed, for some time, in a mixture
of glycerine, one part, and dilute alcohol (six of water to one
of alcohol), one part. The bottle of glycerine jelly is put
intoa cup of hot water, until liquefied, where it is used in the
same way as Canada balsam, excepting that it does not require,
and must not be subjected to, the same amount of heat. A
ring of asphaltum varnish round the cover completes the
mounting.

As I have found lately, that in mounting Conferve and

258 MEMORANDA.

other delicate fresh-water Algz in my glycerine jelly, that the
glycerine, although it preserves the beautiful green colour,
contracts and alters the position of the endochrome,-—to
remedy this evil I propose, énstead of six fluid drachms of pure
glycerine, to add to each fluid ounce of the clarified gelatine
six fluid drachms of a mixture composed of one part of
gelatine to two parts of camphor water, as recommended by
Dr. Carpenter, at p. 245 of ‘The Microscope’ (1856).—Joun
Wiriiam Lawrancz, Peterborough.

On a Method of Preparing and Mounting Hard Tissues for the
Microscope.*— Having for several years occupied my leisure
moments with what are usually denominated “ microscopical
studies,’ I beg leave to offer, as the result of successful ex-
perience, a simple and certain method of preparing and
mounting hard tissues, such as bone, teeth, shells, fossilized
wood, &ce.

I am aware that treatises upon the microscope give a few
indications for the making of sections and embalming them in
Canada balsam ; but they are unsatisfactory either by reason
of their brevity or their want of precision. Specimens may be
procured ready-made from the hands of Topping, Bourgogne,
and others, but while they are expensive, persons in remote
situations are obliged to purchase by catalogue without the
opportunity of selection. Besides, it is oftentimes difficult
or else impossible to obtain series of particular objects, so
that the student must either limit his researches or “ pre-
pare” for himself; in the latter case he may increase his
number of objects indefinitely, and supply himself with many
such as are not attainable from abroad, and divided in any
direction he may require.

A microscopic section should be as thin as the structure of
the object will allow, of uniform thickness, and polished on
both sides, whether it be mounted in the dry way or in
balsam. To meet these requirements, I proceed as follows:

Being provided with—

1. A coarse and fine ’Kansas hone, kept dressed flat with
fine emery ;

2. A long fine Stub’s dentist’s file ;

3. A thin dividing file and fine saw;

4. Some Russian isinglass boiled, stvained, and mixed with
alcohol sufficient to form a ¢olerably thick jelly when cold;

5. A small quantity of Canada balsam ;

6. Slides ;

7. Cover glass ;

* From ‘ Silliman’s Journal.’

MEMORANDA, 259

8. One ounce of chloroform ;

9. One of F.F. aqua ammonie ;

10. Some fragments of thick plate (mirror) glass 1 inch
square, or 1 by 2 inches; and finally,

11. An ounce of “ dentist’s silex,’”” and—

12. Thin French letter paper, of which 500 or more leaves
are required to fill up the space of an inch: I examine the
object and decide upon the plane of the proposed section.

Coarse approximative sections may be obtained with the saw
or dividing file (excepting silicified substances), but these
instruments are not applicable to longitudinal sections of
small human or other teeth, small bones, &c. ‘Take now the
object in the fingers if sufficiently large, and grind it upon
the coarse hone with water, to which add “ silex’”’ if neces-
sary, until the surface coincides with the intended plane.
Wash carefully: finish upon the finer hone; and polish
upon soft linen stretched upon a smooth block.

If the object be too small to admit of immediate mani-
pulation it should be fastened upon a piece of glass with
isinglass—or what is better, upon thin paper well glued with
the same substance upon glass; and a piece of thick paper or
visiting card, perforated with a free aperture for the object,
must be attached to the first paper. This is the guard,
down to which the specimen must be ground with oil; and
its thickness and the disposal of the object require the exercise
of good judgment. Hot water will release everything; and
chloroform remove the grease from the specimen; which,
like that ground with water, is ready for the second part of
the process.

2d. Carefully cover the surface of a piece of the plate glass
with thin French letter paper; next apply a paper guard, as
before stated, but not thicker, for teeth and bone, than
stoth inch; then trace a few lines with a lead pencil upon
the first paper in the little space left in the guard so that the
increasing transparency of a specimen being prepared may be
appreciated ; and finally moisten the “space” with isinglass
to the extent of the object, which must be delicately brushed
over on the ground surface and at the edges with tolerably
thin isinglass before it is cemented in its place. Gentle
pressure should now be employed, and maintained with a wire
spring, or thread wound round about.

In two or three hours the second side may be ground in
oil; silex may be employed at first, or even a file; but these
means must not be persevered in, and the operation must be
completed upon the bare hone. When the second side shall
have been wiped with chloroform it may be polished with a

260 MEMORANDA.

bit of silk upon the finger; and after spontaneous separation
from the paper in hot water the specimen ought to be well
washed on both sides with a camel’s-hair pencil and soap
water, dropped into cold water, and thence extracted to dry.
After immersion in chloroform for a moment, and examination
for the removal of possibly adherent particles, the section
may be declared suitable for mounting.

Before proceeding to this step, a few precautions are neces-
sary about particular sections. Transverse sections of teeth
or bone should be dried, after the preliminary washing,
between glass, in order to avoid the disadvantage of warp-
ing. Very porous parts, such as cancellated bone, or fragile
bodies, such as the poison fang of serpents, require that the
whole structure, or the canals, be saturated with glue and
dried. Sections may now be cut with a saw, ground in oil,
and cemented to the holding-glass subsequent to immersion in
chloroform.

Mounting —Spread a sufficient quantity of old Canada
balsam, or of that thickened by heat (not boiling), upon a slide,
and,when cold, place the section upon it. Have ready a spatula
bearing a quantity of equally inspissated balsam warmed
uatil it flows, with which cover the specimen, and then
immediately warm the slide, being careful to employ the least
possible heat. Now carefully depress the section, and with-
draw every air bubble with a stout needle set in a handle
towards the ends of the slide: put on the cover glass, slightly
warmed, not flat, but allowing one edge to touch the balsam
first, press out superfluous balsam, and the specimen is safe.
The slide may now be cleaned with a warm knife, spirits of
wine, and ammonia.

This communication would be incomplete without some
very important hints concerning “ cover glass.” It is easy to
clean small covers, but very thin glasses or large ones, one or
two inches in length, are not so safely handled. All danger of
breaking is, however, avoided by placing a cover upon a large
clean slide, and wiping one side only with a bit of men damp
with aqua ammonie, and then with a dry piece. The other side
may be cleaned after the mounting.

In the next place, all preparers are aware of the difficulty
attending the use and application of large covers. I beg
leave to assure the inexpert that the following method will
ensure success. Having prepared the cover glass, and super-
imposed it, let it first be gently pressed downwards at many
points, with the flat end of a lead pencil; it will be found,
however, almost impossible to flatten it without breaking,
consequently too much balsam will overlie and underlie the

MEMORANDA. 261

section. Let now a piece of thin paper be laid over the
cover, and upon this a thick slide; if a moderate heat be
applied to both the slides, over and beneath the specimen,
direct pressure, evenly exerted with the finger (or spring
clothes-pins), will force out all unnecessary balsam, and leave
the section and the protecting cover perfectly flat and
unbroken.

The reader will not deem me too prolix when he attempts
his first preparation, or when, after having followed the plans
so scantily given in the books, he feels the need of something
precisely definite. It is certam that neither Canada balsam
nor gum mastic will retain the first ground side of a specimen
upon a slide long enough to enable the preparer to reduce it
to the requisite thinness, and with both these substances
heat must be employed, which is objectionable, because most
objects are thereby warped or cracked ; and, furthermore, the
paper guard, which I hold to be indispensable for limiting
and equalizing the thinness of a section, is not mentioned in
treatises, in which, if known to the author, such a measure
should be noticed. But it is possible to fasten agate, fossil
wood, &c., with hot gum shellac, so that they may be ground
upon both sides with a water stone; but even in these
instances invidious cracks may endanger or destroy the
beauty of a choice preparation.

I am confident that my specimens are second to none in
any respect; and the highly creditable performances of
friends, to whom I have given the method, forming the sub-
ject of this communication, lead me to believe, that with the
facilities it affords, the observers of our country will need no
Topping for objects within their reach, and I beg leave to
add that the profitable pleasure I have enjoyed induces me,
through the ‘ American Journal of Science,’ to invite parti-
cipation.—CuristorHeR Jounston, M.D.

On Actinocyclus and Eupodiscus.— Mr. Edwards, in a paper
“On American Diatomacee,”’ read on the 3d March, states
that he considers the Actinocyclus triradiatus, described by
me in the ‘ Micr. Journ.,’ vol. vi, p. 23, to belong to the genus
Coscinodiscus. I have, however, good evidence that this is
not the case; and that, in fact, it is merely an internal plate,
or perhaps an imperfectly formed valve, of the common
Actinocylus radiaius of Smith. In some gatherings kindly
forwarded to me by Colonel Baddeley, this species is very
abundant, and the peculiar valves, which I had found pre-
viously always in a detached state, occur on many of the
perfect frustules, and I imagine are the newly formed valves,

262 MEMORANDA.

not fully silicified, of frustules undergoing self-division.
Actinocyclus triradiatus must therefore be cancelled entirely.
Mr. Edwards afterwards refers to some remarks on Eupo-
discus, 11 the ‘ Micr. Transactions,’ vol. vu, p. 19, m a way
J do not exactly understand; but my intention there was to
show that the form called Eupodiscus radiatus by Professor
Smith, was distinct from Professor Bailey’s species of the same
name, and in fact a Biddulphia. At |that time I had not
seen Professor Bailey’s species, but having since received
authentic specimens, my opinion is fully confirmed; Bailey’s
species is a true Eupodiscus, with projecting processes or
“feet,” all similar in form, as in FE. argus, and quite
distinct in structure from the form which occurs in the
Thames, and elsewhere on our coasts. The processes are
merely hyaline projections, without any markings, and there
are no spines. I consider, therefore, that Eupodiscus radiatus,
Smith, should be cancelled, and Biddulphia radiata be sub-
stituted for our English species; whilst Hupodiscus radiatus of
Bailey may be considered as a good species, known, however,
at present, only in America.—F. C. 8. Rorrr.

263

PROCEEDINGS OF SOCIETIES.

Microscoricat Socinty, March 30th, 1859.
Dr. Lanxester, President, in the chair.

F. E. Webb, Esq., J. O. Dix, Esq., and Joseph Beck, Esq.,
were balloted for, and duly elected members of the Society.

Dr. Bowerbank read a paper on Grantia ciliata (‘ Trans.,
p- 79).

A paper by Mr. Edwards, ‘On Diatomacez,’ was read
by Mr. Roper (‘ Trans.,’ p. 84).

It was resolved, “That the microscope-makers who adopt
the standard screw be requested to ascertain that one of the
gauge-taps, recommended by the Society, May 19th, 1858,
will enter the bodies of their microscopes to the extent of
three tenths of an inch.”

* For this purpose it will be necessary to omit the cylindrical
fitting beyond the inside screw recommended by the sub-
committee (‘ Trans.,’ Jan., 1858, p. 39) ; retaining, however,
the plain collar on the object-glass to facilitate its attachment.”

“‘N.B.—A supply of taps and screw-tools is now in the
hands of Mr. Williams, the Assistant-Secretary of the
Society.”

The President announced that in consequence of the
soirée on May 5th, the ordinary meeting of April 27th would
not be held.

May 5th, 1859.

The annual soirée was held this evening at the South
Kensington Museum. Although somewhat removed from
the centre of the metropolis, the rooms of the South
Kensington Museum offer so many advantages for a large
gathering, that from the time the Council had obtained the
permission of the Committee of Council on Education to hold
their annual soirée in this magnificent suite of apartments,
they lost no time in making arrangements for a display of
microscopes such as had not been seen in the metropolis

264 PROCEEDINGS OF SOCIETIES.

before. The Council divided itself into committees, each of
which took up certain departments of preparation. One
section of the members saw to the lighting by oil and gas
lamps. Another collected together diagrams illustrative of
microscopic objects. The invitations to country members,
correspondence with exhibitors of microscopes and objects,
were also thus carried on. It was soon found that the large
preparations necessary for the exhibition of the number of
microscopes which were promised would be so expensive that
the funds of the Society would not bear it without bankruptcy.
One of two plans offered, either to collect subscriptions from
members, or to charge a sum on extra tickets required by
members for their friends. The latter seemed the preferable
plan, and, accordingly, each member was allowed, as on
previous occasions, two tickets, and as many others as he
wished for by paying for them. In this way the Council
hoped to defray the expenses of the soirée without making a
demand upon the funds of the Society, which ought to be
devoted to strictly scientific purposes. It is gratifying to
know that this arrangement so far succeeded, that the
Society’s funds have suffered less by it than at any previous
soirée. The fact of the members having become lable for
the tickets they presented to their friends has been mis-
understood, and has led to the report that the tickets were
sold by the Council. This is only true in the sense that
membership is paid for, as the distribution of tickets was
entirely confined to the members of the Society.

In the arrangement of the tables for the exhibition of the
microscopes the committee received the greatest possible
assistance and attention from the officers of the South
Kensington Museum, who contributed all the help that
lay in their power to the preparations necessary for the
reception of the large party expected.

Although nearly 5000 invitations were issued, it was not
anticipated, till the evening of the soirée, that so large a
number of persons would assemble. Long before the hour of
eight o’clock, at which time the company was invited, they
began to assemble, and from this time till eleven o’clock a
continuous stream of visitors passed through the doors. The
next morning it was found that 2847 tickets had been taken
at the doors, so that there can be little doubt that con-
siderably above 3000 persons were present.

The display of microscopes—the great object of the
evening’s assemblage—took place in the new galleries erected
for the reception of the Turner and Vernon pictures. Along
the whole length of these splendid galleries 1000 feet of

PROCEEDINGS OF SOCIETIES. 265

tables were erected for the reception of the microscopes. As
these galleries are not supplied with gas the whole of the
microscopes were lighted with oil lamps, spirit not being
allowed to be burned in the building.

The following is an imperfect list of those who exhibited
microscopes, but as those mentioned were known to have
exhibited, it was thought better to publish their names:

Beale, Dr. 1 Lankester, Dr. 2
Lobb, Henry ll Blenkins . 2
Lege . 2 Roberts . 3
Carpenter, Dr. 2 Hogg 2
Du Pasquier 1 Knight 2
Furze 1 = Farmer 1
Tomkins . 2 Williams 1
Pavy, Dr. 1 = _ Hislop 1
Varley 4 Walford . i
Peel : 2 Mestayer 1
Hopgood . 1 Garnham iL
Millar, Dr. i. sShuter: a
Deane ] Smith I
Ladd, Dr. 3 eB ourr 1
Roper 1 Penkit J)
Mummery 2 | dicks, Dr. 1
Hassall, Dr. dy i ope 1
MAKERS AND OTHERS.

Ross ? ; .16 Topping . 2
Powell and Lealand . 12 Darker 4
Smith and Beck . . 20 #£Society . 4
Ladd A ; . l3 _ Pitehford 2
Pillischer : : Protlieroe 2
Baker . : . 20 Rainey , ee
Salmon . 5 . 16 College of Surgeons and Mr.

Horne and Thornthwaite 5 (¢ Quekett , . 14
Amadio . ‘ . 4 Brodie : rel
Field : j .12 Prendergast 1

The number of microscopes really exhibited amounted to
about 300.

It would be impossible here to enumerate either the forms
of microscopes exhibited, or of the objects by which their
powers were tested. It must suffice to say, that every form
of instrument was present, from the cheap and efficient
instruments of Messrs. Field and Son, of Birmingham; Baker,
Salmon, and Ladd, of London; to the magnificently equipped
instruments which are turned out from the establishments
of Messrs. Powell and Lealand, Ross and Son, and Smith
and Beck. Not only were there lenses of great power
and accurate definition exhibited, but almost every possible

266 PROCEEDINGS OF SOCIETIES.

variety of accessory apparatus. To those who looked upon the
exhibition with an instructed eye, it was a perfect museum of
microscopical apparatus.

As for objects, it would be much easier to indicate things
which were not exhibited than those that were. The
Council had hoped to have arranged the objects in a
classified form, but it was found quite impossible to do this
for so short a space as the evening’s exhibition. It might,
however, be a subject of thought for the Council of the
Microscopical Society, as to whether, at some future period,
they could not organize an exhibition of microscopes, which,
instead of exteuding over a few hours, should extend to a
few days, and thus present a more permanent means of
studying the instruments and their improvements.

May 26th, 1859.
Dr. Lanxester, President, in the chair.

Dr. Eve, James Murray, Esq., and E. J. Meeres, Esq.,
were balloted for, and duly elected members of the Society.

Mr. Beck read a paper “On the Uniform Screw for
Microscopes.”” (‘ Trans.,’ p. 92.)

Mr. Smith exhibited and described a model of a new form
of microscope, remarkable for the smallness of the space in
which the whole of the necessary apparatus was contained.

West Kent Microscoricau Society.

Under this title a society has been formed in the neigh-
bourhood of Blackheath, Lee, and Lewisham, having for
its object the encouragement and promotion of micro-
scopical science, and, although the officers were only
elected on the 2d of June, it already numbers nearly forty
members, many of whom are practical microscopists. Its
officers for the ensuing year are—

President.—John Penn, Esq.

Vice-President.—John F. South, Esq.

Treasurer.— Dr. Noyes.

Secretary.—My. Clift.

Members of Council.—W. Brown, Esq., W. Groves, Esq.,
R. Hicks, jun., Esq., Rev. G. F. Lacey, Rev. R. H. Marten.

INDEX TO

JOURNAL.

VO DU MEP YEE:

A.

Achnanthes (Bory.), 163.
. gregoriana, 84.

Actiniz, On the multiplication of, in
aquaria, 131.

Agelena labyrinthica, 130.

Alder, Josh., On Three New Species of
Sertularian Zoophytes, 131.

Allman, Prof., On the peculiar appen-
dage of <Appendicularia, styled
“ Haus,” 86.

Alternation of Generations and Parthe-
nogenesis in insects, 102.

Amphiprora, 173.

Amphitetras, 181.

Amphora, 173.

Appendiculuria, On a_ peculiar ap-
pendage of, 86.

Aperture, angular, 256.

Aquarium, Mr. Warington’s portable
microscope for the, 199.

Arachnidia hippothooides, 131.

Araneidz, On the Anatomy of the
spinning organs in the, 129.

Archer, W., supplementary catalogue of
Desmidiacee found in the neigh-
bourhood of Dublin, with descrip-
tions, and figures of a proposed new
genus, and four new species, 133.

Ascaroides, n. gen., 239.

Asteromphalus (Ehr.), 157.

Avenella dilatata, 131.

Aulacodiscus (Ehr.), 156.

B.

Barthélemy, M. A., On the occurrence
of a Nematoid Parasite in the ovum
of Limax griseus, 239.

Beale, Lionel, the Microscope in its
application to Clinical Medicine,
Review of, 110.

Bee, On reproduction in the Hive-, 103. |

&

Bermuda tripoli, Dr. G. A. Walker-
Arnott on, 254.

Biddulphia (Gray), 163, 181.

Binocular Vision, On a new law of,
132.

Brightwell, T., On some of the rarer or
undescribed species of Diatomacez,
179.

British Association, Proceedings of,
September, 23d, 1858, 126.

“3 25th, 1858, 129.

C.

Calwellia bicornis, 153.
Campanularia halecioides, 131.
Johnstoni, 131.

Campylodiscus (Ehr.), 157, 179.

Cartilage, Loose, from the knee-joint,
microscopical examination of a, 11.

Catenicellide, 143.
ellaria (Salicornaria) Johnsoni (B.),
65.

Cellulariade, 149.

Cell-wall in petals of flowers, on some
conditions of the, 22.

Cenangium, 239.

Circulation of blood in a fish’s tail,
description of a trough for exhibiting
the, 113.

Claparéde, E., On the calcareous cor-
puscles of the Trematoda, 92.

Clubiona atrox, &c., 130.

Cobbold, T. Spencer, Notes on the
calcareous corpuscles of Tricuspi-
daria, 115.

os Notes on Tricuspidaria
and Pentastoma, 202.
Cocconeis (Ehr.), 156, 171, 179.
5 arraniensis, 80.
rr pinnata, 79.
Coccus adonidum, 102.
» hesperidum, 102.

Cohn, F., On the reproduction of

Nassula elegans, 96.

268 INDEX TO

Coloured discs, John Gorham on the

rotation of, 69.
Corpuscles, calcareous, of Tricuspidaria,

115.
Coscinodiseus, 13, 173.

Fr Normanni, 80.
Cothurnicella, 148.
Creswellia (Arn. and Grev.), 164.
Cupularia canariensis (n. sp.), 66.
is Johnsoni (n. sp.), 67.

Currey, Fred. F.R.S., Mycological notes

by, 225.
Cyclotella, 172.

D.

Dental Tissues, Rainey on the struc-
ture and mode of formation of the,
Zee

Denticella, 13.

Denticula, 207.

Desmidiacez, supplementary Catalogue
of the, found in the neighbourhood
of Dublin, 133.

Diatomaceze in Californian Guano, 155.

internal movements in, 18.

method of cleaning, 167.

35 and Mollusca in the County
of Antrim, On a deposit of, 9.

re new forms of in Firth of
Clyde and in Loch Fine, 60.

new species of British, on,

by R. K. Greville, 79.

2 on some of the rarer or un-
described species of, 179.

Diatoms, marine, on the nature of,
170.

Dickie, Dr. G., on a deposit of Diato-
mace and Mollusca, in the County
of Antrim, 9.

Dingle, the Rev. T., on a new law of
Binocular Vision, 132.

Diplostomum rachieum, 92.

volvens, 92.

Donkin, Dr., notes in reply to Dr.
Walker-Arnott, 5.

Doryphora, 178.

Dredging, an apparatus for, 1

EK.

Edwards, A. M., on a method of clean-
ing Diatomacez, 167.

Epeira, 130.

Epithemia, 176.

Eschara distoma (un. sp.), 66.

Eunotia, 171, 174,179.

F.
Fishes, On the development’ of some
parts of the skeleton of, 33.

”

”

JOURNAL.

Foraminifera, Recent, of Great Britain,
104.

Frankfort, Communication from the
Microscopic Society of, on the inter-
change of specimens, 119.

G.

Gegenbaur, Dr. C., on the development
of Sagitta, 47.
Gibbons, W. S., Microscopic Hints
from Australia, 117.
Glycerine jelly, 257.
Gorham, John, on the rotation of
coloured discs, 69.
Gosse, P. H., Evenings at the Micro-
scope, Review of, 248.
Graphila, 225.
Gray, P., on angular aperture, 256.
Greville, Dr. R. K., on Diatomaceze in
Californian Guano, 155.
on new species of
British Diatomacee, 49.
* note on a structure
observed in Surirella, 116.
on Plagiogramma, a
new genus of Diatomacez, 207.
Guano, Californian, on Diatomaceze
in, 155.

H.

Halecium Beanii and halecinum, 131.

48 labrosum, 131.

D nanum, 131.

Half-hours with the Microscope, &c.,
Notice of, 195.

Harting, Professor, on the Microscope,
Review of, 194.

Hendry, W., on the diagonal scale, 255.
Higgins, the Rev. H. H., on the death
of the common hive-bee, &c., 126.

» on the liability of shells to in-
jury from the growth of a Fungus,
128.

Himantidium, 171.

Hincks, the Rev. T., on a new species of
Laomedea, with remarks on the
genera Campanularia and Laomedea,
131.

5» On some new and interesting
forms of British Zoophytes, 131.

Hive-bee, On the death of the, sup-
posed to be occasioned by a Parasitic
Fungus, 126.

Holostoma cuticola, 94.

Homeocladia, 178.

Humble creatures, “The Earthworm
and the Common House Fly,” Notice
of, 57.

INDEX TO JOURNAL.

Huxley, T. H., Observations on the
development of some parts of the
skeleton of fishes, 33.

I.

Illumination for high powers, Ona mode
of, 114.

Inflammation, On the early stages of, by
Joseph Lister, 139.

J.

Jackson, Geo., On micro-photographic
portraits, 122.

Johnston, Christopher, On a method of
preparing and mounting hard tissues
for the microscope, 258.

Jones, T. R., ‘The Aquarian Naturalist,
&c.’ Review of, 111.

K.

Keates, John, On a mode of illumination
for high powers, 114.

Kolliker, Prof. A., On the development
of the transversely striated muscular
fibre from simple cells, 54.

L.

Laomedea angulata, 131.
oy on a new species of, by the
Rev. T. Hincks, 131.

Lankester, Dr., Description of a Museum
Microscope, 235.

Lawrance, W., on glycerine jelly, 257.

Lepralia discoidea (n. sp.), 66.

Leptocystinema Kinahani, 134.

Portii, 134.

Leuckart, Prof. R., On Alternation of
Genertions. al Parthenogenesis in
insects, 102

on the develop-
ment of Pentastomum tenioides, 182.

Limax griseus, On the occurrence of a
nematoid parasite in the ovum of, 239.

Lister, Joseph, On the early stages of
inflammation, 139.

Lycosa saccata, 130,

M.

Meade, R. H., On the anatomy of the
spinning organs of the Araneide,
129%

Measurement of the vertical thickness
of microscopic objects; and on the
determination of the chemical pro-
perties from their refractive powers,
240.

Menipea, 150.

269

Micro-photographic portraits, Mr. G.
Jackson on, 122.

Microscope, On the optical powers of
the, 27. 7

rs Description of a Museum,

235.

Mr. Warington’s portable aquarium,
199.

Microscopical Society of London, Pro-

ceedings of,122,
204, 263, 266.
3 » of Frankfort,
communication
from, 119.
cn ci of Hull, Pro-

ceedings of,205.
55 - of Victoria, 118.
3 West Kent, 266.

Microscopic hints from Australia, 117.

Milner, W. R., description of a trough
for exhibiting the circulation of the
blood in a fish’s tail, 113.

Mucor, 227.

Muscular fibre, On the development of
the transversely striated, from simple
cells, 54. :

Mycological notes, by Fred. Currey,
BR: 2206

N.
Nassula elegans, On the reproduction of,
6

Navicula, 175.
5 Sorcipata, 83.
Nematoid parasite, On the occurrence
of, inthe ovum of Limaz griseus, 239.
Nitzschia, 171.

PA arcuata, 82.
- macilenta, 83.
O.

Odontidium, 180.
1B

Paul, Benjamin, manual of technical
analysis, &c., notice of, 112.

Patellaria, 227, 228.

Penium Berginii, 138.

Petals of flowers, On some conditions of
the cell-wall in, 22.

Pentastomum tenioides, On the deve-
lopment of, 182.

Pentastoma and Tricuspidaria, Notes
on, 202.

Peziza, 230.

Phlebia, 234.

Phragmidium, 226.

Pinnularia semiplena, 84.

270 INDEX TO

Plagiogramma, a new genus of Diato-
macez, Dr. R. K. Greville on, 207.

Pleurosigma, 180.

Plumularis similis, 131.

Podosira levis, 85.

Polyzoa, Australian, 143.

ep Madeiran, on some collected

by Mr. J. Y. Johnson, 65.

Preparing and mounting of hard tissues,
a method of, 258.

Prescott, H. P., Tobacco and
Adulterations, review of, 251.

its

R.

Rainey, Geo., On the Structure and
mode of Formation of the dental
tissues, 212.

re On the mode of Formation
of Shells of animals, of Bone, and of
several other structures, by a process
of molecular coalescence, &c., review
of, 109.

Rhabdonema, 180.

Rhizosolenia, 13.

Rylands, T. G., On the Epticat powers
of tle microscope, 27.

S.

Sagitta, On the development of, 47.

Salicornariade, 149.

Sertularian Zoopltytes, Mr.
three new species of, 131.

Scale, On the use of the diagonal, 259.

Schultze, Prof. Max., On the phenomena
of internal movements in Diatomacez
of the North Sea, &c., 13.

Scrupocellaria Delilii (Aup. sp.), 65.

Shells, On the liability of, to injury
from the growth of a Fungus, 128.

Spatangidum (Brét.), 161.

Spheria, 230, 231, 232, 233, 234.

Spherozosma pulchellum, 136.

Spinning organs of the Araneide, On
the anatomy of, 129.

Staurastrum O Mearii, 137.

Stauroneis, 176, 180.

Surirella, 179.

on a structure observed in,

Alder on

116.
Synedra, 177.

JOURNAL.

|

Tabellaria, 171.

Tetracotyle, 96.

Thomisus cristatus, 130.

Tobacco and its Adulterations, Notice
of, 251.

Trematoda,On the calcareous corpuscles
of the, 92.

Triceratium, 180.

Tricuspidaria, On the calcareous cor-
puscles of, 115.

- and Pentastoma, Notes

on, 202.

Tryhlionella, 175.

Tubulipora druidica (n. sp.), 67.

Ve
Victoria, Microscopic Society of, 118.

Ww.

Walker-Arnott, Dr. G. A., Reply to
Dr. Donkin, 89.

i; What are Marine
Diatoms? 170.

Wallich, Dr. G. C., an Apparatus for
dredging at moderate depths in the
deep sea; and for capturing floating
objects from shipboard, 1.

Warington, Mr., on the multiplication
of Actiniz in his aquaria, 131.

% R., on a portable aquarium
microscope, 199.

Webb, Dr. W. W., notes of the micro-
scopical examination of a Loose Carti-
lage from the knee-joint, 11.

Welcker, Dr. H., On the measurement
of the vertical thickness of micro-
scopic objects, and on the determi-
nation of the chemical properties
from their refractive powers, 240.

West, Tuffen, On some conditions of the
cell-wall in the petals of flowers, 22.

Williamson, Prof. W. C., On the reecnt
Foraminifera of Great Britain, Review
of, 104.

Z.

Zoophytes, British, the Rev. T. Hincks
on some new and interesting forms
of, 131.

Zoophytology, 65, 143.

JOURNAL.
ERRATUM IN Vot. VII.

Page 27, for ‘ P. G, Rylands,” read “ T. G. Rylands.”

PRINTED BY J. EF.

ADLARD, BARTHOLOMEW CLOSE.

Nea a HAM ie “Wh

a ruby ia ee

i

Nur Journ Vol VL _

Fig.3

Big 4a

AU AIS es
ye ‘

: i « fs a © :
Dean ec
AN Cees

\
os Saray
oS

{

JOURNAL OF MICROSCOPICAL SCIENCE.

DESCRIPTION OF PLATE T,

Illustrating Mr. West’s paper on the Structure of Flowers, &c.

Fig.

eines aquatilis, profile view, inner surface of petal.

2.—Iris, ditto, ditto.

3.—Ten weeks’ Stock, ditto, ditto.

4.—Pyrethrum parthenium, ditto, ditto.

5.—Scarlet Geranium, ditto, ditto.

6.—Orchis pyramidalis, ditto, ditto.

7.—Sweet William, ditto, ditto.

8.—Comfrey, ditto, ditto.

9.—Gladiolus ; a, profile, inner surface; 4, cells of same, as seen from

above.
10.—Galium verum ; a and 4, as seen from above ; c¢, sectional view of same.

11-—Pansy, knotted hair from the throat: 4, portion of same more highly
magnified.

12.—Verbena; a, hair from the throat of; 4, portion of same more highly
magnified, showing section ; ¢, one cell of petal, from above, showing
angular sinuosities, with small pats of secondary deposit at the pro-
jecting angles.

13.—Musk-plant, large hair from the petal, accidentally bent over near the
tip. x 400 diameters.

14.—Pelargonium ; a, profile view of inner surface of petal; 4, two cells of
same from above, showing the folds radiating from the centre, and
the little teeth-like patches of secondary deposit.

15.—Periwinkle, one cell of petal of, in profile.

16.—Clove-pink, small portion of petal in profile.

17.—White poppy, ditto.

JOURNAL OF MICROSCOPICAL SCIENCE.

DESCRIPTION OF PLATE II,

Illustrating Prof. Max. Schultze’s paper on the Phenomena of
Internal Movements in Diatomacex of the North Sea.

Fig.
14, ehielsiohis styliformis, Brightwell.

1. A perfect living specimen. x 72 diam.

2, 3. The ends of two specimens still adhering to one another
after the division in different positions. x 180 diam.

4. The end of a specimen which had been made red-hot, showing
the characteristic surface marking. At a, a, are places which
possibly are apertures in the shell. x 180 diam.

5—10.—Rhizosolenia calcar avis, mihi.

5. A living example. x 72.

6. A similar one in the act of division. x 72.

7. The two ends of aspecimen. x 330.

8. The inferior ends of two examples adhering to each other, in
the interior of which newly developed points lie. x 180.

9a. One of the newly developed points shown in fig. 8, at a, a.
x 330.

10 a. One of the points shown at 4, 4, in fig. 8. x 330.

11, 12.—Denticella regia, mihi.

The former is shown alivey the latter without its organized con-
tents, and caught whilst dividing. The position of the
nucleus is only indicated by the dark granular masses extend-
ing themselves in a radiate manner. Both x 180 diam.

13.—€oscinodiscus centralis, Ehrenberg. Alive. X 180 diam. The sculp-

ture of the shell is so fine that it is not visible with so low a

power. It is adapted also in its organized contents to the other

Coscinodisci occurring at Heligoland.

These figures are all drawn with Nobert’s camera lucida.

ee EE rl Or !™DLUCCl eeeemrmrtltC TC

~

oo a

ro eo a
Wy 8 Ven 4

Mucr- Sourn. Vi VI Pt If.

TH H.ad nat.del. Tuffen. West sc

JOURNAL OF MICROSCOPICAL SCIENCE.

DESCRIPTION OF PLATE III,

Illustrating Mr. Huxley’s paper on the Development of the
Caudal Skeleton in the Stickleback (Gasterosteus Ciurus.)

Fig.

1.—tThe tail of a young fish, 5-16th of an inch long.
2.—The tail of a young fish, 7-16th of an inch long.
3.—The tail of a half-grown specimen.
4.—The tail of a full-grown Gasterosteus.
The two last figures are drawn in their proper relative proportions, while
figs. 1 and 2 are on a much larger scale than figs. 3 and 4.
The letters have the same signification throughout.

“Pes BPRS VASO XR

= §

. Centrum of the last distinct vertebra.
. Urostyle.

. Notochord.

. Neural arch of the last distinct vertebra.

. Interior arch of the same vertebra.

. Inter-hemal cartilage or bone of the last ordinary vertebra.
. Anterior hypural apophysis.

Posterior hypural apophysis.

. Principal caudal fin-rays.

Interneural cartilage or bone of last ordinary vertebra.

. Anterior epiural apophysis.
. Posterior epiural apophysis.

o. Superior accessory fin-rays.

. Inferior accessory fin-rays.

JOURNAL OF MICROSCOPICAL SCIENCE.

DESCRIPTION OF PLATE VI,

Illustrating Dr. Greville’s paper on New British Diatomacez.

Fig.
1.—Cocconeis pinnata, Greg.
2—- 45 Arraniensis, Grey.

3.—Coscinodiscus Normanni, Greg.

4—7.—Nitzschia arcuata, Greg.

8, 9.— z macilenta, Greg.
10, 11.—Navicula forcipata, Grev.
12.—Pinnularia semiplena, Grev.

18, 14.—Achnanthes Gregoriana, Grev.
15—17.—Podosira levis, Greg.

All the figures are x 400 diameters, except that of Coscinodiscus Normanni,
which is x 800.

ry “re nth Pot

Mf f 1 7 7 / o F
MO SOW Vol. VIL Pvt}

‘ - of

“i

—__

Pereeseriiiereeet
PARAL AAA aN gael

Sen

WWest imp.

°.
(er

00K

aha ty Coe OUTTUE TN SY AE ITETT NT I VV ET

EEE yawn

SERAP AAA A ese maniehdad 4414 hide anoannnn ret?”

=1 on

ee

youn 7A

fio fone OU

a CY

Goo Hanon

calp.

Tuffen West s

iy PL id Ai Ole a) A : Meal ud ANT > ye v4 RRA ¥ bal
a fr) rane owt Na ae at 4
; ; ix pre’ oa ‘ < hie
7 ma f Ar). uit v ae, Re tl ’
Os i

sie A

‘
j
a
i a
4 “4
aoe?) pcan
ina)
®
' Rete,
®
“- .
¥
A
4
. x
’
“a
{
igs?
:
be
=
és
"
5
~
;
+
> ”
vf yi)
AS
‘ ‘

*, Te sek ae

a bese” 36
an od

|
"ye.
“?

Nucr Journ Vi Vi Pt VIL

W.West imp.

Vest sc.

1 6 Toffen V

ile de

Grevi

RK

=je:
ax eae
ae

UGE

09000084

809500500

20000000 9020050005000 008 anions
exe

\opoeenpcd0000e 000009 20%

W West ump.

R.EGreville del. Tuffen West sc

JOURNAL OF MICROSCOPICAL SCIENCE.

DESCRIPTION OF PLATES VII, VIII,

Illustrating Dr. Greville’s paper on Diatomacez in
Californian Guano.

PLATE VII.
Fig.
1.—Cocconeis regalis.*
2.—Aulacodiscus Oreganus.
3.—Campylodiscus stellatus.
4.—Asteromphalus flabellatus ? with straight rays.
5.—The same? with the hyaline area nearly centrical and the rays straight.
6.—Asteromphalus elegans.
7.—Spatangidum Ralfsianum, very large ; the hyaline area nearly centrical,
and the rays nearly straight.
3.—The same ; typical in its characters.

PLATE VIII.

9.—Achnanthes angustata.
10.— Biddulphia longicruris.
1l.— Y Roperiana ; side view.
12.—The same; front view.
13.—The same ; front view, approaching self-division.
14.— Cresswellia turgida.
15.—Cresswellia (?) ferox ; frustules in union.
16.—The same ; a valve seen vertically.

The figures are x 400 diameters.

* Since this paper was written I have seen a species much resembling this,
in guano from Algoa Bay, in which I find it had also been previously
detected by several friends. It has been suggested that it may be only the
sporangial state of Cocconeis Grevillit. It remains to be seen, however,
whether it be really identical with the one I have figured. The view of the
upper valve from within has not occurred to me in Californian guano ; nor
the view represented in the plate, in Algoa Bay guano.

JOURNAL OF MICROSCOPICAL SCIENCE.

DESCRIPTION OF PLATE IX,

Illustrating Mr. Brightwell’s paper on various Diatomacez.
Fig.
1.—Zunotia eruca, Khr.
2.—Cocconeis coronata, Nn. sp.
3.— , jfimbriata,n. sp.
4.—Campylodiscus striatus, Bhr.
5.—Surirella limosa, Bail.
6.—Stauroneis Fulmen, n. sp.
7.—Pleurosigma longina, W. Sm.
8.—Odontidium speciosum, n. sp.
9.— o punctatum, n. sp.
10.— rf Baldjickii, n. sp.
11.—Rhabdonema mirificum, W. Sm.
12.—Triceratium (2) dubium, un. sp.
13.—Amphitetras cruz, 0. sp.
14.— + antediluviana (?), probably a valve from a sporangial
frustule.
15. Biddulphia Balena, Uhr.

Figures 5, 6, 7, 11, 14, 15 x 300 diamete rs; the remainder 400.

MNior Journ. VU VL Pb,

ees.

Bose Gi
O95 969059! >

0 8Bo5 85 Pogo to seo ca:
ogatopepogo5 0a Cag Sou:

1095 2a S62 0n920080)

3
+208 i ,
Seo Reo
Cogene Socezagss suave ceoMctagoe 223500 Coy osocuGo Oe,
99009026 909 cateascuao Sever Leocata gd soucan GG
905050505005 99, cage 8 °o2afCo,
ROB ESOL Oop CS gcacoeeSo%s Seca Seo sje h0E 8:

FONE,
cS SUI|NSS

ery

1 sit

i ea

W.West immo

Tuffen West sc.adnat

at

“i > et

Ny
i us

apt

si

nm)

we wae

At

ef op F id
ids he Me AMA Ors

o
~

4999098 a

i

=
ayadaadaner
ae a II

BE vavccucc caguapaauie avavnuncyarersroncpe nnccgsrase
pe essans wane ® .

err etoc ones ce esagmasotenae BUTT T9

pd eae eo DOo DA Ose OtT

Eros oinnsen pia ee gnobi seem anree ce
REA eT

. Sree es genie e foaas ant

Hea i aK

| ra NPAT

O80 coseres pace
eae 8.009 SP 920070080000 070 SS OROMINTAN? ® aes

sana aaagadada
GA EEAEGEEUAUEERRLEANE

Sule agen nananasoge Bae eg ena nia
ST NGREEL TD acLTUEEeo

0 oe 9000009999000 09550905050708299 80 ODonDeIA NS 24H)
eee oD wba Sema aedasedadd sow eben so atid ss. eam

opasaddagadagagadaunasodoosanasadaannano:

6009520059995. :
999590999 a9 98895909
99999999 9999999990
oo905099909 99909999900

992009 O,000 an
SEER EE Jo 0g000999

THVT ATITY YTNTTTYTTT

16

Lt}

=C He

a4

Nest

i

+ Tors
ei. iuiien V

RKG d

JOURNAL OF MICROSCOPICAL SCIENCE.

DESCRIPTION OF PLATE X,

Illustrating Dr. Greville’s paper on Plagiogramma, a new
genus of Diatomacez.

Fie.
Te Dis ageationd Gregorianum ; side view.
2.—The same; front view.
3.—P. Jumaicense ; front view.
4.—P. pulchellum ; side view.
5.—The same; front view; chain of five frustules.
6.—The same; a large example ; front view.
7.—BP. tessellatum ; side view.
8.—P. validum ; side view.
9.—P. ornatum ; front view.

10.—P. inequale ; front view.

11.—P. pygmeum ; side view.

12.—P. obesum ; side view.

13.—The same; front view.

14.—P. lyratum ; side view.

15.—P. Californicum ; side view.

16.—The same ; front view.

17.—The same; front view, with fewer vitta.

All the figures are x 400 diameters.

JOURNAL OF MICROSCOPICAL SCIENCH.

DESCRIPTION OF PLATE XI,
Illustrating Mr. Currey’s Mycological Notes.

Fig.
i, 2, and 3.—Graphiola Phenicis, Poit.
1—A vertical section of the fungus highly magnified.

a. The black outer crust (which is a ring, zo¢ @ cup), apparently
formed of the disorganized tissue of the leaf.

6. A layer, formed either of very minute cells or of granular matter.

c. Elongated cells of the tissue of the leaf.

d, Inner roundish cells of the tissue of the leaf.

eé. Delicate, closely packed threads, springing from the granular
layer, and marked with very faint transverse lines on septa.

J. A mass of yellowish, small spores, resting on the threads, and
probably formed from the breaking off of the terminal cells of
the threads.

2.—Vertical section of another specimen, less highly magnified.
3.—Vertical section of the fungus deprived of its outer carbonaceous coat,
and showing the threads or fibres (? formed from the tissue of the
leaf) traversing the mass of spores. x about 50 diameters.
4.—Fruit of Phragmidium bulbosum, deprived of its stalk, and germinating
from one of its joints.
5.—Two joints of a broken fruit of Phragmidium bulbosum germinating
from the upper joint.
6.—A germ-filament of Phragmidium bulbosum differing from the usual
form, as pointed out in the text.
7.—Spores of Mucor fusiger, Lk. x 220.
8.—Fruit of Patellaria clavispora, B. and Br.; a—e, stylospores; f and I
sporidia. x 325, except 6, whichis x 450.
9.—Patellaria atrata, Fr.; a, ascus, with unripe sporidia; 8, ¢, d, ripe
sporidia.
10.—Stylospores of Patellaria atrata, ¥r.
11, 12.—Vertical sections of pycnidia of Cenangium Cerost. x highly.
13.—Sporidia of Spheria Zobelii, Tul.
14.—Stylospores of Spheria Tiliaginea, Currey. X highly. :
15.—Fruit of Spheria ciliaris, Sow.; a, ascus, with sporidia; 4, secondary
fruit.
16.—Spheria obtecta, n. sp.; a, ascus, with sporidia; 4, c, secondary fruit
17.—Germinating sporidia of Spheria stercoraria, Sow.
18.—Spheria Spartii, Nees; a, ascus of the usual form; 4, ascus ruptured
at the apex («), and with the inner membrane protruding,
19.—a, sporidia of Spheria macrospora, Desm.; 4, fruit of Coryneum
macrosporium, Berk.

All the figures are X 325 diameters, except where otherwise stated.

MAG hk ly

X

Nae

i

a
YT TOMA
HY wind aie
Ri

SOSA,

BBs keS:

P3493

30 Ge

JOURNAL OF MICROSCOPICAL SCIENCE.

DESCRIPTION OF PLATE XII,

Illustrating Mr. Rainey’s paper on the Formation of Dental
Tissues.
Fig.
' 1.—a. Portion of silicious cuticle from sugar-cane, as seen from above.
é. The same, from below.
ce. Vertical section.
2.—Undulated margin of entirely uncalcified dentine-matrix, fom the
specimen given in outline at fig. 4.
3.—Dentine in different stages of development; from fetal calf. The
lines in the engraving necessary to indicate the spaces between the
dentine fibres and globules, do not exist in the specimen from which
the drawing was taken.
4.—Tooth from foetal calf in very early stage, gently removed from the
subjacent pulp; ¢, tooth; p, dental pulp.
5.—Globular dentine; from human tooth.
6.—Horizontal section of dentine; from human tooth decalcified.
7.—Enamel in different stages of development; from foetal calf.
8.—Matrix dividing into two layers; m, matrix before dividing; e, m,

enamel matrix, with particles of enamel; d, m, dentine matrix.

IPN

3 2044