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COMPARATIVE ZOOLOGY, 


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Founded by private subscription, tn 1861. 


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QUARTERLY JOURNAL 


MICROSCOPICAL SCLENCE: 


EDITED BY 


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


GEORGE BUSK, F.R.C.8.E.,. F.R.S., F.L.S., 


VOLUME VI. 


ith Allustrations on Good and Stone. 


LONDON: 
JOHN CHURCHILL, NEW BURLINGTON STREET. 
™ 1858, 


ORIGINAL COMMUNICATIONS. 


Description of a New Form of Naxrp-ryvep Mepvusa (Thau- 1 
mantias achroa), with Histological Details. By T. SpeNcER 
Cossoxp, M.D., F.L.S., Lecturer on Botany at St. Mary’s 
Hospital Medical School, London. 


(Communicated to Linnean Society, March, 1857.) 


On the 13th of August, 1856, after filling a marine aqua- 
rium, containing about three gallons of water, I detected a 
small naked-eyed Medusa swimming vigorously near the sur- 
face. This minute creature was immediately made the subject 
of careful study, and it turned out to be a species of Thau- 
mantias new to Britam (fig. 1, Pl. 1). So far as I can ascer- 
tain, it has not been described by any author abroad; I have 
therefore thought it worthy of a separate notice. The water 
containing the Medusa had been procured four days pre- 
viously from the shore near Leith, and had been kept in an 
earthen vessel hermetically closed. The animal was only 
preserved alive until the 16th of the same month, in conse- 
quence of injuries sustained during a prolonged and often- 
repeated microscopic examination. 

Referring to the various organs in detail, I allude in the 
first place to the umbrella. The form and general aspect of 
this structure resembles that of the more typical species, being 
hemispherical, transparent, colourless, smooth, slightly elon- 
gated vertically when in a state of rest, the transverse diame- 
ter measuring rather more than the third of an inch, and 
becoming much increased during contraction, the length of 
the disc, at the same time, being proportionately lessened. 
To remark particularly on such admeasurements may appear 
triflimg, but it is useful as an aid to diagnosis, because the 
animal bears a very marked resemblance to Thaumantias 
punctata and T. Thomsoni. These, however, present a more 
depressed umbrella. Again, it is similar, at first sight, to 
T. convexa ; but this species has the umbrella more cylindrical, 
and there are other distinguishing characters, which will be 
alluded to presently. The circumferential portion of the um- 
brella is frmged by twenty-four tentacula of extreme delicacy 
and unusual length ; also, by eight ocelli, a circular gastro- 
vascular canal, and a well-defined shelf-like veil directed 
inwards. These parts will be considered separately. Under 

VOL. V1. B 


2 COBBOLD, ON A NAKED-EYED MEDUSA. 


a quarter-inch objective, the external convex surface of the 
umbrella presented a few well-defined and sparsely scattered 
cellules, which were rather irregularly disposed beneath the 
transparent, and, in such situations, slightly elevated, epider- 
mis (fig. 2). No other indications of structure were noticed. 

The ¢entacula, while relaxed and motionless, are fully three 
times the length of the dise—a peculiarity serving to distin- 
guish this Medusa from all other British species, their peculiar 
arrangement (5 x 4+ 4) also constituting a satisfactory 
mark of identification. During the gentle agitation of the 
water it frequently happened that the tentacula stretched 
beyond this length, the trailing filaments assuming an almost 
invisible tenuity, but when violent contraction occurred, the 
threads suddenly acquired the form of minute tubercles, bor- 
dering the circumferential margin of the umbrella. A gradual 
unfolding usually commenced immediately after the contrac- 
tion—-the exciting agent bemg removed—the extension inva- 
riably originating at the base of the filament, and proceeding 
uniformly downwards to the extremity, until each succeeding 
portion was unfurled. Incompletely extended, the tentacles 
always appear clavate at the tip. Amplified 50 diameters, 
they exhibit a finely granular and ringed appearance, analo- 
gous to that of the prehensile labiate organs of hydroida (fig. 
3) ; with an ordinary pocket-lens indications of knotting may 
be seen at the extremity of the cirrhi. To the naked eye the 
tentacular bulbs appear colourless and homogeneous, but under 
a magnification of 300 diameters, the sub-epidermic tissues 
display numerous closely packed fusiform cells, identical with 
those described as lying beneath the cuticle of the umbrella 
(fig. 9). They refracted light very strongly, but the exist- 
ence of nuclei could not be demonstrated. At the bulb the 
cells are irregularly disposed ; a little further down they begin 
to assume symptoms of grouping, co-ordinate with which 
bulgings appear at the margin of the thread. Lower still, 
the fusiform particles acquire an mcompletely linear arrange- 
ment, speedily merging into a definite series of rings or 
knots, placed at regular intervals. While the cirrhus is re- 
laxed the cell-groups are separated by a transparent interspace, 
which is much constricted, but exceeds in length the paren- 
chymatous knot. Near the extremity of the thread the cells 
are more cogently developed, and being placed at a right 
angle to the axis of the filament, appear to stand out from the 
investing epidermis (fig. 4). At the upper part the tentacula 
exhibit lateral lines in their interior, denoting the presence of 
a central canal, the markings becoming more conspicuous 
near the bulb (fig. 9). This last-named structure, viewed by 


COBBOLD, ON A NAKED-EYED MEDUSA. 3 


transmitted light, appears more opaque than the filament, m 
consequence of its greater thickness, and the abundance of 
those highly refracting fusiform particles already described. 
The limitmg membrane of an otolitic vesicle was discernible, 
but there were apparently no vibratory movements within the 
cavity. 

The ocelli, eight m number (2 x 4), are placed round the 
circular margin of the disc, at intervals, between every third 
tentacle—an arrangement somewhat peculiar. The unassisted 
eye failed to detect their presence ; a very slight enlargement, 
however, rendered them visible. Magnified 60 diameters, 
each ocellus was seen to consist of a transparent vesicle con- 
taining a round nucleus at the base, and in addition, five 
bright yellow, highly refracting globules (fig. 8). The latter, 
larger than the nucleus, varied in size respectively, the diffe- 
rence being uniform and gradational. Under a quarter-inch 
lens these variations in size were more obvious, the bulk of 
the central and superior globule bemg paramount. The wall 
of the sac was now seen to be double, the ocellus bemg sup- 
ported by a cellular thickening of the ining membrane of the 
circular gastro-vascular canal (fig. 10). When under exami- 
nation, the nucleus broke up, and many of the tissues, else- 
where, disintegrated, while the animal was still living in an 
enfeebled condition. 

The marginal vessel is about the width of the filamentary 
tentacle, and to the unassisted eye its walls appear transpa- 
rent and homogeneous. Two kinds of corpuscles, large and 
small, are contained within the canal; of these we shall speak 
more particularly when referring to the circulation. 

The shelf-like veil is directed inwards at a right angle to 
the axis of the disc, and, though broad and conspicuous, offers 
no structural indications. 

The sub-umbrella is placed rather higher than midway be- 
tween the marginal ring and the convex surface of the disc. 
The depth of the concavity lessened during contraction, but 
not uniformly so, it bemg observed that the upper part re- 
mained unaffected, to the extent of a third of its area, from 
the summit downwards, the circular limit of this rigid portion 
forming, as it were, a point d@appui for the development of 
contractile action throughout the remainder of the membrane. 
No muscular tissue, properly so called, could be detected. 

The proboscidiform peduncle has all the features common 
to the genus. It is about the twentieth part of an inch in 
length, quadrangular, and provided with four simple or 
slightly fimbriated triangular lips (fig. 5). The contained 
stomachal cavity was thrown into various shapes during the 


aT COBBOLD, ON A NAKED-EYED MEDUSA. 


lateral and twisting contractile movements of the peduncle, 
but viewed from above, while empty and im a state of rest, 
the walls were symmetrically disposed in the form of a cross 
(fig. 7). With the help of a pocket-lens the lips presented a 
finely granular or ground-glass-like appearance, which was 
due to the abundance of those minute fusiform cellules form- 
ing, as we have seen, the general parenchyma of the body. 

The functionally combined respiratory and nutritive sys- 
tem of vessels, or gastro-vascular canals, are five in number— 
four radiating and one cireumferential—as in other gymnoph- 
thalmatous genera; their walls are transparent, well defined, 
and rigid. The smaller kind of the contained corpuscles are 
rather less in diameter than human blood-globules; while the 
larger, apparently mother-cells, are nearly three times greater, 
possessing nuclei of variable size, but frequently identical in 
character with the lesser globules. All are transparent and 
colourless, with the limiting membrane sharply marked (figs. 
9, 10, 11). When the circulation was active, the corpuscles 
moved in a moderately rapid and regular manner, their course 
in the radiating vessels being continuous from one half of the 
hemisphere to the other. In other words—two vessels carried 
the particles from the marginal canal, convergingly, to the 
central point of intercommunication, on the one hand, and 
two conveyed the same elements from the centre, divergingly, 
on the other (fig. 7). The behaviour of the corpuscles led me 
to conjecture the presence of cilia within the canals, though 
they were not structurally demonstrated. In regard to the 
presumed continuity of the vessels with the stomach in this 
genus, at the summit of the umbrella, let it suffice me to add, 
that I could discover no opening or any interposed channel 
of communication. The enlarged central vascular space 
formed at the crossing of the radiating canals, was the only 
indication of a supra-stomachal cavity ; through this space the 
corpuscles rolled on uninterruptedly (fig. 11). 

The reproductive glands—four in uumber, elongated or 
semiclavate—are placed on the inferior surface of the sub- 
umbrella, a short way distant from the margin, and in the 
course of the radiating canals. Their border to the naked eye 
was smooth, but under a half-inch objective the surface looked 
undulating, an appearance due to the bulging of the ovarian 
cells lying immediately beneath. Each gland was subdivided 
by one of the radiating vessels traversing its long axis (fig. 6). 
The subjacent ova at the surface severally displayed an outer 
cell-wall with its included transparent albumen, a second 
membrane surrounding the molecular yolk, and a third con- 
stituting the germinal spot, within which were three or four 


LISTER, ON INVOLUNTARY MUSCULAR FIBRE. 5 


rounded particles, beautifully distinct (fig. 12). Deeper in the 
organ were similar cells, smaller in size and imperfectly de- 
veloped, evidently destined to supply the place of those ripe 
for expulsion. The connecting tissue between and among 
these ova displayed many of the ordinary parenchymatous 
cellules within its substance. 

To facilitate identification, I subjoin in conclusion a few 
particulars gathered from Professor Forbes’s monograph, in 
which Thaumantias inconspicua, T. punctata, and T. Thomsoni 
differ from this species. The first has the dise wider and 
more flattened, also, purplish-coloured glands and twenty ten- 
tacles. The second has thirty-two tentacula, is a larger 
species, with the umbrella more depressed. The third has 
but sixteen tentacula, the bulbs and reproductive glands con- 
taming a yellow pigment. There is no other British species 
for which it can be readily mistaken. The great length of 
the tentacula forms a distinctive peculiarity. I have desig- 
nated this Medusa, Thaumantias achroa (&xpoos, colourless). 


On the Minute Srructure of Invotuntrary Muscutar 
Fisre. By Josepn Lister, Esq., F.R.C.S. Eng. and 
Edin., Assistant-Surgeon to the Royal Infirmary, Edin- 
burgh. Communicated by Dr. Curistison. 


(From the ‘Transactions of the Royal Society of Edinburgh” Read 
December ist, 1856.) 


Ir has been long known that contractile tissue presents 
itself in the human body in two forms, one composed of fibres 
of considerable magnitude, and therefore readily visible under 
a low magnifying power, and marked very characteristically 
with transverse lines at short intervals, the other consisting 
of fibres much more minute, of exceedingly soft and delicate 
aspect, and destitute of transverse striae. The former variety 
constitutes the muscles of the limbs, and of all parts whose 
movements are under the dominion of the will; while the 
latter forms the contractile element of organs, such as the 
itestines, which are placed beyond the control of volition. 
There are, however, some exceptions to this general rule, the 


B § 


6 LISTER, ON INVOLUNTARY MUSCULAY FIBRE, 


principle of which is the heart, whose fibres are a variety of 
the striped kind. 

Till within a recent period the fibres of unstriped or invo- 
luntary muscle were believed to be somewhat flattened bands 
of uniform width and indefinite length, marked here and 
there with roundish or elongated nuclei; but in the year 
1847, Professor Kélliker of Wurzburg announced that the 
tissue was resolvable into simpler elements, which he regarded 
as elongated cells, each of somewhat flattened form, with 
more or less tapering extremities, and presenting at its 
central part one of the nuclei above mentioned. These 
* contractile” or “ muscular fibre-cells,” as he termed them, 
were placed in parallel juxtaposition in the tissue, adhering 
to each other, as he supposed, by means of some viscid con- 
necting substance. In the following year the same distin- 
guished anatomist gave a fuller account of his discovery in 
the first volume of the ‘ Zeitschrift fiir Waissenschaftliche 
Zoologie,’ and described in a most elaborate manner the ap- 
pearances which the tissue presented in all parts of the body 
where unstriped muscle had been previously known to occur, 
and also in situations, such as the iris and the skin, where 
its existence had before been only matter of conjecture, but 
where the characteristic form of the fibre-cells, and of their 
“rod-shaped ” nuclei, had enabled him to recognise it with 
precision. Confirmations of this view of the structure of 
involuntary muscular fibre were afterwards received from 
various quarters, one of the most important being the obser- 
vation made in 1849 by Reichert, a German histologist, that 
dilute nitric or muriatic acid loosens the cohesion of the fibre- 
cells, and enables them to be isolated with much greater facility. 
In 1852 I wrote a paper “On the Contractile Tissue of the 
Tris,” published in the ‘ Microscopical Journal,’ in which I 
gave an account of the involuntary muscular fibre contained 
in that organ in man and some of the lower animals, stating 
that the appearances I had met with corresponded exactly 
with Kdélliker’s descriptions, and illustratmg my remarks 
with careful sketches of several fibre-cells from the human 
iris, isolated by tearing a portion of the sphincter pupille 
with needles in a drop of water. In 1853, another paper by 
myself appeared in the same Journal, “ On the Contractile 
Tissue of the Skin,” confirming Kdlliker’s recent discovery 
of the “arrectores pili,’ and describing the distribution of 
those little bundles of unstriped muscle in the scalp. These 
and other investigations into the involuntary muscular tissue 
convinced me of the correctness of Kolliker’s observations, 
and led me to regard his discovery as one of the most beau- 


LISTER, ON INVOLUNTARY MUSCULAR FIBRE. 7 


tiful ever made in anatomy; and this is now, I believe, the 
general opinion of histologists. 

Still, however, there are those who are not yet satisfied 
upon this subject. In Miiller’s ‘ Archives’ for 1854, is a 
paper by Dr. J. F. Mazonn of Kiew, in which the author 
expresses his belief that the muscular fibre-cells of Kolliker 
are created by the tearing of the tissue in preparing it, and 
denies the existence of nuclei in unstriped muscle altogether ; 
but he gives so very obscure an account of his own ideas re- 
specting the tissue, that his objections seem to me to carry 
very little weight, more especially as the appearances which 
he describes require, according to his own account, several 
days’ maceration of the muscle in acid for their development. 
In June of the present year (1856), Professor Ellis, of Uni- 
versity College, London, communicated to the Royal Society 
of London a paper entitled “ Researches into the Nature of 
Involuntary Muscular Fibre.’ In the abstract given in the 
‘ Proceedings’ of the Society, recently issued, we are in- 
formed that, “ having been unable to confirm the statements 
of Professor Kolliker respecting the cell-structure of the 
involuntary muscular fibre, the author was induced to under- 
take a series of researches into the nature of that tissue, by 
which he has been led to entertain views as to its structure 
in vertebrate animals, but more especially in man, which are 
at variance with those now generally received.” In the 
“summary of the conclusions which the author has arrived 
at,’ we find the following: “In both kinds of muscles, 
voluntary and involuntary, the fibres are long, slender, 
rounded cords of uniform width » Tn neither 
voluntary nor involuntary muscle is the fibre of the nature 
of a cell, but in both is composed of minute threads or fibrils. 
Its surface- -appearance, in both kinds of muscle, allows of the 
supposition that in both it is constructed in a similar way, 
viz., of small particles or ‘sarcous elements,’ and that a 
difference in the arrangement of these elements gives a 
dotted appearance to the involuntary, and a transverse striation 
to the voluntary fibres.” “On the addition of acetic acid, 
fusiform or rod-shaped corpuscles make their appearance in 
all muscular tissue ; these bodies, which appear to belong to 
the sheath of the fibre, approach nearest in their characters 
to the corpuscles belonging to the yellow or elastic fibres 
which pervade various other tissues; and from the apparent 
identity in nature of these corpuscles in the different textures 
in which they are found, and especially in voluntary, as com- 
pared with involuntary muscle, it is scarcely conceivable that 
in the latter case exclusively they should be the nuclei of 
oblong cells constituting the proper muscular tissue.” 

VOL. VI. c 


8 LISTER, ON INVOLUNTARY MUSCULAR FIBRE. 


Mr. Ellis, then, agrees with Mazonn in believing that the 
tapering fibre-cells of Kélliker owe their shape to tearing of 
the tissue; and he regards the nuclei as mere accidental ac- 
companiments of the proper muscular structure, probably 
belonging to the sheath of the fibres, which, according to 
him, are of rounded form and uniform width. 

The distinguished position of Mr. Ellis as an anatomist 
makes it very desirable that his opinion on this important 
subject should be either confirmed or refuted, and the object 
of the present paper is to communicate some facts which 
have recently come under my observation, and which, I hope, 
may prove to others as unequivocally as they have done to 
myself, the truth of Kolliker’s view of this question. 

In September last, being engaged in an inquiry into the 
process of inflammation in the web of the frog’s foot, I was 
desirous of ascertaining more precisely the structure of the 
minute vessels, with a view to settling a disputed point 
regarding their contractility. 

Having divided the integument along the dorsal aspect of 
two contiguous toes, I found that the imcluded flap could be 
readily raised, so as to separate the layers of skin of which 
the web consists, the principal vessels remaining attached to 
the plantar layer. Having raised with a needle as many of 
the vascular branches as possible, I found, on applying the 
microscope, that they included arteries of extreme minute- 
ness, some of them, indeed, of smaller calibre than average 
capillaries. A high magnifying power showed that these 
smallest arteries consisted of an external layer of longitu- 
dinally arranged cellular fibres in variable quantity, an 
internal exceedingly delicate membrane, and an intermediate 
circular coat, which generally constituted the chief mass of 
the vessel, but which proved to consist of neither more nor 
less than a single layer of muscular fibre-cells, each wrapped 
in a spiral manner round the internal membrane, and of 
sufficient length to encircle it from about one and a half to 
two and a half times. They are seen to have more or less 
pointed extremities, and are provided with an oval nucleus at 
their broadest part, discernible distinctly, though somewhat 
dimly, without the application of acetic acid. The tubular 
form of the vessels enables the observer, by proper adjust- 
ment of the focus, to see the fibre-cells in section; they are 
then observed to be substantial bodies, often as thick as they 
are broad, though the latter dimension generally exceeds 
the former. The section of the nucleus is in such cases 
invariably found surrounded by that of the substance of the 
fibre-cell, though occasionally placed eccentrically in it. 
From the circular form of its section the nucleus appears to 


LISTER, ON INVOLUNTARY MUSCULAR FIBRE, 9 


be cylindrical. These fibre-cells are from z}5 inch to 735 
inch in length, from 3355 inch to 3,555 inch in breadth, and 
about z3!55 inch in thickness, measurements on the whole 
rather greater than those given by Kolliker for the human 
intestine, the chief difference being that in the frog’s arteries 
they are somewhat broader and thicker. 

Now, the middle coat of the small arteries is universally 
admitted to be composed chiefly of involuntary muscular 
fibre; but in the vessels just described it consists of nothing 
whatever else than elongated, tapering bodies, corresponding 
in dimensions with Kolliker’s fibre-cells, and each provided 
with a single cylindrical nucleus imbedded in its substance. 
Considering, then, that no tearmg of the tissue had been 
practised in the preparation of the objects, but that the parts 
were seen undisturbed in their natural relations, it appeared 
to me that the simple observation above related settled the 
point at issue conclusively. 

It was, however, suggested to me by an eminent physiolo- 
gist, that the various forms in which contractile tissue occurs 
in the animal kingdom forbid our drawing any positive 
inference regarding the structure of human involuntary 
muscle from an observation made on the arteries of the frog. 
Beimg anxious to avoid all cavil, and understanding that Mr. 
Ellis’s researches had been directed chiefly to the hollow 
viscera, I thought it best to examine the tissue in some such 
organ. For this purpose I obtained a portion of the small 
intestine of a freshly killed pig, selecting that animal. on 
account of the close general resemblance between its: tis- 
sues and those of man. The piece of gut happened'to be 
tightly contracted, and on slitting it up longituglimally, the 
mucous membrane, which was thrown into loége folds, was 
very readily detached from the subjacent parts” E raised one 
of the thick, but pale and soft fasciculi of the circular coat, 
and teased it out with needles in a drop of water, reducing it 
without difficulty to extremely delicate fibrils. On examining 
the object with the microscope, I found that it was:composed 
of mvoluntary muscular fibre, almost entirely unmixed with 
other tissue, reminding me precisely of what I had seen in 
the human sphincter pupille, except that the appearances 
were more distinct, especially as regards the nuclei, which 
were clearly apparent without the application of acetic acid. 
Several of the fibre-cells were isolated in the first specimen 
I examined, each one presenting tapering extremities about 
equidistant from a single elongated nucleus. The fibre-cells 
were of soft and delicate aspect, generally homogeneous or 
faintly granular, with sometimes a slight appearance of lon- 
gitudinal strie. 


~ 


10 LISTER, ON INVOLUNTARY MUSCULAR FIBLE. 


I had now seen enough to satisfy my own mind that the 
involuntary muscular fibre of the pig’s intestine was similarly 
constituted with that of the human iris and the frog’s artery: 
but before throwing up the investigation, I thought it right 
to examine carefully some short, substantial-looking bodies 
of high refractive power, which at first sight appeared, both 
from their form and the aspect of their constituent material, 
totally different in nature from the rest of the tissue. Hach 
is seen to be of somewhat oval shape, with more or less 
pointed extremities, and presents several strongly marked, 
thick, transverse ridges upon its surface ; and each, without 
exception, possesses a roundish nucleus whose longer diameter 
lies across that of the containing mass. Yet between these 
bodies and the long and delicate homogeneous fibre-cells 
above described, every possible gradation could be traced. 

In several cells one half was short, with closely approxi- 
mated rugze, the other half long and homogeneous. Hence 
it was pretty clear that the appearances in question were 
due to contraction of the fibre-cells, and that the shortest 
of these bodies were examples of an extreme degree of 
that condition; their substantial aspect and considerable 
breadth being produced by the whole material of the long 
muscular elements being drawn together into so small a 
compass. The rounded appearance of the nuclei was ac- 
counted for by supposing either that they had themselves 
contracted, or that they had been pinched up by the con- 
tracting fibres, of which explanations the latter appears the 
more probable. 

In order to place the matter if possible beyond doubt, I 
prepared two contiguous portions of the circular coat of a 
contracted piece of imtestine in different ways; the one by 
simply cutting off a minute portion with sharp scissors, so as 
to avoid as much as possible any stretching of the tissue, the 
other by purposely drawing out a fasciculus to a very consi- 
derable length, and then teasing it with needles. In the 
former preparation, the fibre-cells appeared all of them more 
or less contracted, except in parts where the slight traction 
inseparable from any mode of preparation had stretched the 
pliant tissue, which in the fresh state appears to yield as 
readily to any extending force as does a relaxed muscle of a 
living limb. In the other object, where the tissue had been 
purposely stretched, most of the fibre-cells were extended, 
and possessed elongated nuclei. Here and there one would 
be seen of excessive tenuity, scarcely broader at its thickest 
part than the nucleus, looking, under the highest magnifying 
power, like a delicate thread of spun glass. To how great a 
length the fibre-cells admit of being drawn out in this way 


LISTER, ON INVOLUNTARY MUSCULAR FIBRE. i} 


without breaking I cannot tell. Among these extended 
fibres, however, there lay, here and there, an extremely 
contracted one, the result, I have no doubt, of the irrita- 
tion produced by the needles upon the yet living tissue. In 
order to guard against this source of fallacy, I kept a piece 
of contracted gut forty-eight hours, and then examined two 
contiguous parts of the circular coat in the way above 
described. The muscle was much less readily extended than 
in the fresh state, and I found that, where stretching of the 
tissue had been avoided as much as possible, it was composed 
entirely of fibre-cells marked with transverse ridges of vary- 
ing thickness and proximity; a minute fibril having, under 
a rather low power, the general aspect represented in fig. 17. 
But I saw no distinct examples of the extreme degree of con- 
traction so frequent in muscle from the same piece of intes- 
tine in the fresh state. This confirmed my suspicion that 
the latter had been induced by the irritation of the mode of 
preparation. On the other hand, a fully stretched fasciculus 
showed its fibres everywhere destitute of transverse rugze, so 
that the point was now distinctly proved. Kdlliker, in his 
original article in the ‘ Zeitschrift ftir Wissenschaftliche Zoo- 
logie,’ figured some long fibre-cells with transverse lnes 
upon them—“ knotty swellings,” as he termed them,—which 
he supposed probably due to contraction, and he repeats this 
hypothesis in the part of his ‘ Mikroskopische Anatomie,’ 
published in 1852. The proof of the correctness of this idea 
is now, I believe, given for the first time. 

The bearings of these observations on the main question 
respecting the structure of involuntary muscular fibre are 
obvious and important. In the first place, if the short, sub- 
stantial bodies were mere contracted fragments of rounded 
fibres of uniform width, we should expect them to be as 
thick at their extremities as at the centre, instead of which 
they are always more or less tapering, and often present a 
very regular appearance of two cones applied to each other 
by their bases. Secondly, the uniform central position of 
the nuclei in the contracted fibres, proves clearly that the 
former are no accidental appendages of the latter, to which 
it seems difficult to refuse Kolliker’s appellation of cells. 

The effect of acetic acid on the involuntary muscular 
tissue is to render the fibres indistinct, but the nuclei more 
apparent; and if this reagent be applied to a piece of con- 
tracted muscle, many of the nuclei are seen to be of more or 
less rounded form. The deviation of the nuclei from the 
“rod-shape”’ has hitherto been a puzzling appearance, but is 
now satisfactorily accounted for. 

In examining a fasciculus that had been fully stretched, 


12 LISTER, ON INVOLUNTARY MUSCULAR FIBRE. 


forty-eight hours after death, I met with several good speci- 
mens of isolated fibre-cells. Though these fibres are very 
long, yet we have no reason to believe that anything near 
the extreme degree of extension has been attained in them, 
and we cannot but contemplate with amazement the extent 
of contractility possessed by this tissue. 

In one of the drawings is represented a portion of a fibre- 
cell curled up, which has been mtroduced for the sake of the 
clear. manner in which it shows the position of the nucleus 
imbedded in it. Just as in the case of the fibres wrapped 
round the arteries of the frog’s foot, this cell might be seen 
im section by proper adjustment, and that section is observed 
to be oval; proving that the fibre is not round, but somewhat 
flattened. It happens that the nucleus appears at this point ; 
its section is circular, and is surrounded on all sides by the 
substance of the cell. 

The pig’s intestine seems to be a peculiarly favorable situa- 
tion for the investigation of unstriped muscle. Judging from 
Kolliker’s measurements, the fibres appear to be of much 
larger size there than in the same situation in the human 
body. The length of the fibre-cell 3 is 3; inch. The fibre 
2 is imperfect at one extremity; but, taking the double of the 
distance from its pointed end to the nucleus, its length is 35 
inch. These measurements are between three and four times 
greater than any which Professor Kolliker has given for the 
human intestine, and considerably exceed the length of the 
“colossal fibre-cells ”? which he describes as occurring in the 
gravid uterus. The individual fibre-cells, with their nuclei 
and transverse markings, if they have any, are quite distinctly 
to be seen with one of Smith and Beck’s 34, object-glasses. 
But in order to examine their structure minutely, a higher 
power is required: that which I use is a first-rate +,, made 
several years ago by Mr. Powell, of London. The principal 
HN arg of the fibre-cells from the pig’s intestine are as 
under 


Length of fibre-cell, 3 - yy inch. 
Breadth of ditto ‘ : - 3500. 39 
Length of nucleus of ditto Iood » 
Breadth of ditto B000 9» 
Breadth of fibre-cell, 16 ‘ - 3000 0» 
Thickness of ditto . ; : : =d00 2» 
Length of fibre-cell, 13 ‘ > Fea OD 
Breadth of ditto : . Fede 
1 


Longitudinal measurement at nueleds of ditie sB00 
Transverse ditto 


Length of fibre-cell, 15 ual 


LISTER, ON INVOLUNTARY MUSCULAR FIBRE. 13 


Hence it appears that the length of the most contracted 
fibre-cell is the same as that of the nucleus of an extended 
one. The fibres vary somewhat in breadth, independently of 
the results of contraction. Thus, one in the extended condi- 
* tion which I sketched, but which is not here shown, measured 
only 555 ich across. The nuclei of the uncontracted fibres 
are very constantly of the same length, and are good examples 
of the rod-shape to which Kolliker has directed particular 
attention. They always possess one or two nucleoli, and have 
often a slightly granular character; occasionally, as in fig. 21, 
they present an appearance of transverse markings. One 
frequently sees near the nucleus of a fibre that has been 
artificially extended from the contracted state, an appearance 
of a gap in the substance of the cell, forming a sort of exten- 
sion of the nucleus, asif the fibre generally had been stretched 
more completely than the nucleus. Mr. Ellis lays great stress 
on a dotted appearance which he considers characteristic of 
tavoluntary muscular fibre. I must say I agree with Kolliker 
in finding the fibre-cells, for the most part, homogeneous when 
extended, or faintly marked with longitudinal strie.* No 
doubt dots are present in abundance; but these, so far as I 
have observed them in the pig’s intestine, are distinctly exte- 
rior to the fibres, though adherent to their surface; and I 
suspect them to be little globules of a tenacious connecting 
fluid. 'That the fibre-cells do stick very tightly together, 
may be seen by drying a minute portion of the tissue, after 
which they will be found shrunk, and slightly separated from 
one another, but connected more or less by minute threads. 
To sum up the general results to which we are led by the 
facts above mentioned. It appears that in the arteries of the 
frog, and in the intestine of the pig, the involuntary muscular 
tissue is composed of slightly flattened elongated elements, 
with tapering extremities, each provided at its central and 


* The longitudinal stria above referred to, are probably due to a fine 
fibrous structure in the substance of the fibre-cells. When in London, last 
Christmas, I had, through the kindness of Dr. Sharpey, the opportunity of 
examining a specimen of muscle from the stomach of a rabbit; which he had 
prepared after Reichert’s method. The nitric acid had not only detached 
the fibre-cells from one another, but also brought out very distinetly in each 
muscular element the appearance of minute parallel longitudinal fibres, 
which seemed to make up the entire mass of the fibre-cell except the 
nucleus. Ina plate accompanying the paper on the Iris, before referred to, 
I gave figures of some fibre-cells with distinct granules arranged in longi- 
tudinal and transverse rows. This appearance, which, however, so far as 
my experience goes, is exceptional, and is hardly sufficiently marked to de- 
serve the appellation “dotted,” is probably caused by unequal contractions 
in the constituent material.—April 2d, 1857. 


14 RALFS, ON DIATOMACE. 


thickest part with a single cylindrical nucleus imbedded in 
its substance. 

Professor Kélliker’s account of the tissue bemg thus com- 
pletely confirmed in these two instances, and the description 
here given of its appearance in the arteries of the frog’s foot 
being an independent confirmation of the general doctrine, 
there seems no reason any longer to doubt its truth. 

It further appears, that in the pig’s intestine the muscular 
elements are, on the one hand, capable of an extraordinary 
degree of extension, and, on the other hand, are endowed 
with a marvellous faculty of contraction, by which they may 
be reduced from the condition of very long fibres to that of 
almost globular masses. In the extended state they have a 
soft, delicate, and usually homogeneous aspect, which becomes 
altered during contraction by the supervention of highly 
refractmg transverse ribs, which grow thicker and more 
approximated as the process advances. Meanwhile, the “ rod- 
shaped” nucleus appears to be pinched up by the contract- 
ing fibre till it assumes a slightly oval form, with the longer 
diameter transversely placed. 

I will only further remark, that these properties of the 
constituent elements of involuntary muscular fibre explain, in 
a very beautiful manner, the extraordinary range of contrac- 
tility which characterises the hollow viscera. 


Nores on the S1uicrous Cety of Diatomacem. 
By J. Rarrs, Esq. 


Tur few remarks now offered to the British Association, 
“upon the siliceous cell formed within the frustules of 
several Diatomaceze,” have been written rather to stimulate 
the researches of my fellow-students, and to elicit their 
opinions, than to communicate any new facts. 

I believe that in my description of Fragilaria (Himan- 
tidium) pectinalis, in 1843, I was the first to indicate the 
occurrence of these cells, in the following words: “ Within 
the frustule there is apparently another siliceous frustule, the 
lateral margins of which are rounded, having striz like the 
outer frustule. In the longer frustules it is nearly elliptic, 
but in the shorter ones appears as if truncated at the ends, 
and in both it occupies the whole interior of the frustule, 
except the corners where the puncta at the ends are situated ; 


RALPS, ON DIATOMACES. 15 


it is filled with a yellowish, granular mass, mixed with 
numerous colourless vesicles.” Subsequently, the presence 
of these internal cells has been, in two instances (Meridion 
Zinckent and Himantidium Soleirolit), adopted as part of the 
specific character. In this conclusion I could not concur, 
because I found in the same filament such frustules inter- 
spersed with others in the common state. More recently, in 
Professor Smith’s beautiful work on the British Diatomaceze, 
we have had his opinion respecting this condition of Meridien 
circulare thus stated : 

“Tn var 6. we meet with a curious modification in the 
growth of the frustule, which has been regarded by some 
observers as characteristic of a distinct species. re 
A close examination of such frustules, especially in the living 
state, has led me to the conclusion that the appearance of a 
double wall of silex is owimg to the formation within the 
original frustule of a second perfect cell, instead of the usual 
mode of division by which the original frustule is divided 
into two half-new cells. In the present case, the central 
vesicle, or cytoblast, becomes enlarged without division, and 
secretes on its extension two new valves, which are pushed 
outwards until they lie in close approximation with the 
original valves. ‘This process is not always repeated, the 
usual mode of self-division again recurs, and two valves are 
formed in the interior of this new cell according to the nor- 
mal method. This unusual method of development is not, 
however, sufficiently constant to warrant the separation of 
such frustules from the species in which it occurs, perhaps 
hardly sufficient to constitute a variety, as frustules in both 
the ordinary and abnormal states may be met with in the 
same gathering, and even in the same filament.” 

As part of the above explanation seems to me inconsistent 
with what I have observed, I am anxious briefly to state my 
own views, and to solicit a re-examination of the phenomena 
by Professor Smith himself, satisfied that it would either 
induce him to modify his opinions, or by the discovery of 
new facts dissipate the uncertainty which at present may 
reasonably be entertained of the nature of these internal 
cells. 

Although it is true that “we frequently find in the same 
filament cells thus formed, and others following the normal 
mode of growth,” as I formerly showed, yet I cannot agree 
to Professor Smith’s statement under Himantidium Soleirolii, 
that “there is no doubt of its being merely an accidental 
modification of cell-growth.” On the contrary, I believe it 
to be a reproductive state of the species, and consequently to 
have a definite and important part in their economy. 


16 RALFS, ON DIATOMACES. 


For several years I have attentively watched the circum- 
stances connected with the formation of these ner cells in 
Himantidium undulatum, by gathering specimens at short 
intervals. During great part of the winter, the filaments 
increase in bulk, by repeated division of the frustules, until 
they form large masses, filling the ditches; at length the 
inner cells make their appearance, at first sparingly, but as_ 
spring advances, it is difficult, in many situations, to obtain 
a filament without them. I have found that when these 
become abundant, the filaments cease to grow, and the entire 
mass soon breaks up and disappears. The same thing hap- 
pens in the other species of Himantidium, and in Meridion. 

I do not find that the inner cell commences in the centre, 
and pushes its valves outwards, as stated by Professor Smith. 

Vere this the case, the internal matter also would necessarily 
be pushed outwards by the advancing valves, and thus con- 
densed between them and the walls of the frustule. On the 
contrary, in the Himantidium the internal matter, before 
nearly fluid, collects within the new cell, becomes dense and 
more granular, and the new walls are formed round it in the 
situation they are to occupy, leaving an empty space between 
them and the walls of the frustule. 

The alteration and condensation of the colourmg matter, 
and the appearance, or at least great increase of vesicles, have 
a strong resemblance to what takes place previous to the 
formation of sporangia, the completion of which, as in this 
case, usually preludes the death and disappearance of the mass. 

As in most acknowledged sporangia, the cell thus formed 
always tends to assume an oval or orbicular form. It, how- 
ever, is very frequently, and perhaps generally, divided in 
halves, as in the fission of the frustules, so that the oval 
seems made up of two neighbouring frustules ; but this is not 
the case, as may readily be ascertained by noticing the mar- 
ginal puncta of the original frustule. 

Do these newly constituted cells ever continue to divide, 
as Professor Smith supposes? I believe not; at least I have 
never seen a specimen in which the semi-elliptie portions 
were separated by the interposition of other valves resembling 
either themselves or those of the ordinary frustule. For my . 
own part, I have been unable to trace the species after the 
formation of these cells, owing to the quickly succeeding 
disappearance of the mass. If, indeed, this renewed division 
does occur, the resemblance to what takes place in the 
sporangia of some species of Melosira would be increased. 

Professor Smith, in his most interesting and valuable 
account of the ‘Reproduction in the Diatomacez,’ enume- 


ROPER, ON BRITISH MARINE DIATOMACESA. 17 


rates four modes in which sporangia are formed. The third 
is thus defined : 

“The valves of a single frustule separate, the contents set 
free, rapidly increase in bulk, and finally become condensed 
into a single Sporangium.” 

As far as regards the Melosira varians, the only one in 
. this group which I have had an opportunity of noticimg, I 
believe the process is essentially the same as in the examples 
already described. The only difference is, that the new- 
formed cell being inflated, and much larger than the original 
frustule, the valves of the frustule must necessarily be either 
ruptured or pushed apart by the increasing growth of the 
sporangium, and the latter alternative happens. 

I have seen no specimen of Mr. Brightwell’s Chetoceros 
Wighamii, but from his figures I believe the goniothecia- 
like bodies constitute another example of the formation of 
internal cells. 

I have said that I consider these internal cells sporangia, 
and essentially of the same nature as the inflated ones of 
Melosira varians. At the same time we should not forget 
that Mr. Thwaites discovered the Himantidium pectinale in a 
truly conjugated state, and that it is contrary to our experi- 
ence of the economy of nature that the same result should 
be obtained in the same species in two different ways. 


Notes on some New Spectres and Varieties of Britisn 
Marine Diatomacez. By F.C.S. Rorrr, F.L.S., F.G:S. 


Tue greater part of the British fresh-water species of 
Diatomaceze, from the facility with which they are obtained, 
and the frequent opportunities for collecting them offered to 
every observer with a microscope, have probably been already 
described; but that this is not the case with the marine spe- 
cies, is shown by the great additions lately made to this class 
by the researches of Dr. Gregory, Mr. Brightwell, and others ; 
and, as they appear to have been hitherto somewhat neglected 
on our Southern coasts, I hope to draw more particular at- 
tention to this abundant field of origimal observation by 
pointing out the best means of obtaining the marine species, 
and at the same time propose to describe a few of the more 


18 ROPER, ON BRITISH MARINE DIATOMACEA. 


peculiar forms that have occurred to myself within the last 
two years. 

The mud of tidal harbours, and the creeks and pools on the 
banks of estuaries, such as occur in the Thames, Poole Har- 
bour, &ec., have been the chief source of supply of our present 
marine flora of this class. But a large number of the more 
interesting species are only to be obtaimed by dredging or 
collecting the various species of filamentous marine Algze at 
the lowest spring tides. These should be gathered in consi- 
derable quantity, thoroughly washed, and left for some short 
time in water, so that all the Diatomacez may become de- 
tached. The sediment must then be allowed to subside, a 
portion of it bemg preserved for the examination of any new 
or interesting forms in a living state, and the remainder 
treated with acid in the usual way. The sand and any re- 
mains of the Algze not dissolved by the acid may then be 
removed by subsidence, on the plan recommended by my 
friend Mr. Okeden, in the ‘ Microsc. Journal,’ vol. i, p. 158, 
which is preferable to that of Dr. Munro, described at page 
241 of the same volume, as it is impossible to prevent the 
admixture of gatherings from different localities by this 
process, though when that is not an object it has some 
advantages. 

From an examination of the species described in Professor 
Smith’s ‘Synopsis,’ I find that out of 455 species included in 
that work as indigenous to Great Britain, 231 are from fresh 
water, 82 occur in brackish water, and 142 are marine; and 
of this latter number 72 have been collected from Poole, 
Pevensey, Hull, and the Thames, whilst 10 were obtained 
from molluscs, and only 6 are described as dredged in deep 
water. That this gives a very imperfect notion of the nume- 
rous species to be found at a considerable distance from the 
shore is shown by the examination of the gatherings in 
which the greater part of the new species now to be described 
were found. 

The Caldy gathering, which was made in five to six fathoms 
water, contains many rather rare and interesting forms, in- 
cluding Coscinodiscus concinnus, Biddulphia Baileyii and 
rhombus, EHucampia zodiacus, Nitzschia spathulata, and Melo- 
sira Westii, and I have altogether met with sixty-six species 
described by Professor Smith. In the Lyme Regis gathering, 
from a depth of five to eight fathoms, Synedra undulata, 
Amphora costata, Campylodiscus Hodgsonit and Ralfsii, Na- 
vicula crabro, and Rhabdonema Adriaticum occur, and I have 
already found seventy-nine species included in the ‘ Synopsis.’ 

In addition to the new species and varieties which I now 
proceed to describe, there are numerous other forms in both 


ROPER, ON BRITISH MARINE DIATOMACES. 19 


these gatherings of which the characters are so doubtful that 
it is impossible to determine satisfactorily their specific, or, in 
some cases, even generic position. All the drawings are mag- 
nified 400 diameters. 


Eupodiscus tessetatus, n. s.—Cellular structure distinctly 
hexagonal, with a small rounded nodule at each angle of the 
hexagons. The surface of the valve slightly elevated, flat, 
with a declining margin, of about one fifth of the diameter ; 
pseudo-nodule single, submarginal.- Colour of dry valve 
brown. Diameter :002”; diameter of cellules -000066" (fig. 
i avand 6,'Pl: 111). 

Marine. Caldy, Pembrokeshire, Rev. J.Guillemard; Hum- 
ber, Mr. Norman. 

I received the first specimens of this very pretty species in 
a gathering obtained by the Rev. J. Guillemard, by washing 
a collection of small Algze, from the shore of Caldy Island, 
near Tenby, and have since met with it im some slides sent by 
Mr. Norman from dredgings in the Humber. It belongs to 
the same class as H. crassus, fulvus, and Ralfsii ; which differ 
from HE. argus, the typical species, m having merely one 
circular spot or pseudo-nodule near the margin, and not dis- 
tinct processes, as in that species. The cellular structure is 
very peculiar, and unlike any other Diatom that I am ac- 
quainted with, excepting coscinodiscus concinnus, each angle 
of the hexagons bemg marked with a small dot or boss, as 
shown in fig. 1 0, requirmg a magnifying power of 800 to 
1000 diameters to bring out distinctly. The valves, when 
seen with a low power, have so much the appearance of a 
small piece of mosaic that I have named it ¢esselatus. 

This species differs from EH. radiatus, the only form with 
hexagonal cells, placed, I thik doubtfully, in this genus by 
Professor Smith, in the peculiar arrangement of its cellules, 
and in wanting the elevated processes and spines, which would 
rather lead me to place that species with the Biddulphias 
than in its present position.* 


* Professor Smith, at p. 47 of the second volume of the ‘Synopsis,’ 
alluding to this species, states that it differs from Biddulphia ‘in the orbi- 
cular outline of the valve, and in the processes being rather projections 
from the disc than produced angles.” I have, however, specimens of B. 
turgida, which are very nearly orbicular, and I cannot agree that the pro- 
cesses simply rise from the surface of the disc, as shown in t. lxii, f. 255, 
of the ‘Synopsis,’ but are projections rising gradually from the centre of the 
valve, with cellular structure continnous nearly to their apices, exactly as in 
B. rhombus, many specimens of which are also nearly orbicular. In addi- 
tion, the processes in Eupodiscus are all similar in structure, whilst in Z. 
radiatus we have two cellular projections, and two spines, as in B. Baileyit, 
and generally in B. aurita. 


20 ROPER, ON BRITISH MARINE DIATOMACE. 


From a careful examination of the figures in Ehrenberg’s 
‘ Microgeologie,’ I consider this species may be synonymous 
with his Coscinodiscus limbatus, t. xx, f. 29, or Cos. fimbriatus, 
t. xxii, f. 2, but there is no pseudo- nodule given in the figures, 
and without authentic specimens it is impossible to refer it 
with any certainty to either of these species. 


Coscinodiscus concinnus.—‘ Synopsis,’ vol. 1, p. 85. 

Marine. Caldy, Pembrokeshire, Rev. J. Guillemard ; 
Humber, Mr. Norman (fig. 12). 

This interesting species, discovered by Professor Smith, 
and described in the Appendix to vol. 11 of the ‘ Synopsis,’ 
occurs with tolerable frequency in the Caldy gathermg, and 
I have received remarkably fine specimens, through the 
kindness of Mr. Norman, from dredgimgs in the Humber. 
Although not a new form, it has not yet been figured, and as 
the large size of the specimens enables me to add some further 
points to those already given by Professor Smith of the 
peculiarities of its structure, I may be excused for cluding 
it in these notes. 

The description given in the ‘Synopsis’ is as follows: 
“ Cellules arranged im radiating lines, equal except im centre 
of valve, where there occur three to eight larger cellules ; 
cellules 24 im 001"; diameter :0025" to -0056."” This is 
perfectly correct as far as it goes, except as to size, my 
specimens ranging from ‘004 to -013”, or nearly double 
the size of Professor Smith’s. But the larger specimens 
show plainly a point that is not easily discernible in those 
under ‘O04 in diameter, namely, a submargmal row of 
minute spines varying from ya4yoth to zo!)pth of an inch apart, 
according to the size of the disc, and from each of which 
there is a radiating line almost to the centre of the valve. 
The celiules themselves are hexagonal and formed on the 
same peculiar plan as already described im Eupodiscus 
tesselatus, and shown im fig. 1 8 The large irregularly 
formed cells in the centre havi ing hkewise dots at their a angles. 
The valve is very convex ; so much so in the larger specimens, 
that when the central cells are in focus with a high power, 
the circumference is almost invisible. It differs in this 
respect from Cose. per, foratus, to which it is most nearly 
allied, that species having much the form of a lmette watch- 
elass, flat im the centre, with a narrow sloping margin. The 
cellules are also much smaller in C. concinnus. 

With these new facts the following description might be 
given of the species: “Valves very convex, with minute 
hex xagonal cellules arranged in radiating lines, divided at 


ROPER, ON BRITISH MARINE DIATOMACE. 21 


short intervals by rays, extending from a band of submarginal 
spines almost to the centre, where there occur from three to 
eight irregularly shaped larger cellules.” Cellules 10 to 26 
in 001”; diameter 0025” to :018”. 

I figure a small specimen as the structure is precisely 
similar, and cellules vary little in size from those in the 
largest valves, those with 10 to 20 in :001 being rather rare, 
and I have only found them of this size in the specimens 
from the Humber. 


Coscinodiscus labyrinthus, un. s.—Cellules hexagonal, minute, 
arranged in quincunx in large irregular hexagonal spaces, 
divided by lines of confluent cellules or dots; valves not 
spinous at the margin, but with a ring of minute submar- 
ginal papille. Diameter :0018" to 00247” ; diameter of hexa- 
gonal spaces ‘00027" to -00038”; cellules 15 in ‘001" (fig. 2 a 
and 8). 

Marine. Caldy, Pembrokeshire, Rev. J. Guillemard. 

I have only met with four specimens of this peculiar species 
in the slides I have examined from the Caldy gathering, but 
the arrangement of the cellules is so different from any yet 
figured, that it may fairly be entitled to rank as a new 
species. It has somewhat the aspect, under a low power, of 
a finely marked specimen of C. eccentricus, but differs in the 
absence of the spmous margin, and in the peculiar arrange- 
ment of the cellules, which have somewhat the appearance of 
whorls or coils of dots, as shown in fig. 2 5, the surface of 
the valve being thus divided into large and irregularly shaped 
hexagonal spaces, without any clearly defined margin. C. 
eccentricus occurs abundantly in this gathermg; but neither 
in this nor in any other locality in which I have met with it, 
has there been any tendency to a similar arrangement of the 
cellular markings. 


Coscinodiscus (?) stellaris, n. s.—Cellular markings very 
minute, with five or six larger cells or dots arranged as a star, 
in the centre; surface slightly convex; margin not spinous ’ 
colour of dry valve, brown. Diameter -00252” (fig. 3). 

Marine. Caldy, Pembrokeshire, Rev. J. Guillemard. 

The detached frustules and single valves of this species are 
abundant in the Caldy gathermg. The markings on the 
surface of the disk are exceedingly fine, and have much the 
appearance of the transverse striz on Pleurosigma angulatum, 
even when seen with an 4-objective and oblique light. The 
star-like arrangement of cells or dots is found in the centre 
of both valves, and is readily distinguished with a magnifying 
power of 200 diameters. The strize are so inconspicuous, and 


22 ROPER, ON BRITISH MARINE DIATOMACES. 


valve so hyaline, when mounted in balsam, that it has probably 
hitherto escaped notice, from being considered a detached 
ring or connecting membrane of C. radiatus or eccentricus. 

I was at first inclined to refer this species to Podosira, but 
the slight convexity of the valve, and the absence of the appa- 
rent perforation at the apex characteristic of that genus, are, 
T consider, sufficient to preclude its bemg so classed. The 
frustules being always separate and never in filaments, distin- 
guish it from Melosira, and the want of any process or 
pseudo-nodule separate it from Eupodiscus It differs from 
the finest-marked specimens of Coscinodiscus eccentricus 1m 
the absence of the eccentric limes and spinous margin, and 
from all other species of that genus in not having distinct 
cellular markings. 


Coscinodiscus (?) ovalis,n.s.— Valves oval, with finely dotted 
striz radiating from the centre to the circumference ; of a dull 
slate colour when dry, and light brown in balsam. Length 
00158" to :0023" ; breadth -00128” to :00149” (fig. 4). 

Marine. Caldy, Pembrokeshire, and dredged off Tenby, 
Rev. J. Guillemard. 

The valves of this species occur abundantly in the Caldy 
gathering, and in the washings of Vesicularia dredged in five 
fathoms off Tenby. Professor Smith informs me that he does 
not see any satisfactory evidence for referring this species to 
the Diatomacee ; and although I differ from so high an au- 
thority with great reluctance, I still record it, though with 
some doubts as to its generic position, in the hopes that the 
attention of observers in other localities may be directed to 
it, in order to clear up the doubtful poimts in its structure. 
That it belongs to the Diatomacez I think admits of little 
doubt ; the frustules are siliceous, composed of two valves 
very slightly convex, and occur abundantly in gatherings, 
almost confined to various species of marme Diatoms. The 
radiating strize on the surface of both valves are delicate, and 
require a magnifying power of 400 diameters to make them 
out satisfactorily; but the arrangement of the dots or 
cellules is very similar to that of many other species of the 
class. 
The general outline of the valves agrees with that of some 
species of Cocconeis, but the absence of a median line and 
central nodule separate them from that genus. It is very 
probable that it may be entitled to rank as a distinct genus ; 
but as I have not had any opportunity of examining it in a 
living state, I place it provisionally in Coscinodiscus, to 
which, in general structure, it appears most closely allied. 


ROPER, ON BRITISH MARINE DIATOMACES. 23 


I have met with a few specimens of the same form in a 
gathering of M. De Brébisson’s, containing Nitzschia palpe- 
bralis, &c., from Normandy, kindly sent me by Professor Smith. 


Actinocyclus triradiatus, nu. s.—Valve with three rays, the 
surface covered with minute puncta or dots, with faint lines 
connecting them ; the rays formed by slight elevations, with 
a more closely dotted structure. Diameter -003" to ‘004 (fig. 
5 a and 0). 

Brackish water. Near Caermarthen. 

This species occurs occasionally in clay, obtamed by my 
friend, Mr. Okeden, from a brick-yard near Caermarthen, de- 
posited probably by the tidal estuary that runs up to that 
town. The general structure of the valve differs from all the 
described species of this genus, having no distinct margins to 
the segments, or any pseudo-nodule in the centre of the valve. 
I consider, however, that it must be referred to Actinocyclus 
without hesitation, and should have adopted Ehrenberg’s 
name of Ternarius, but, from the figure in the ‘Microgeologie,’ 
that species appears to have distinct cells, and the rays are 
similar to those in A. undulatus, and not elevations, or pro- 
bably thickened cell-walls, as in this species. The peculiar 
arrangement of the dots is shown in the enlarged fig. 5 6. 


Nitzschia virgata, n. s—F. V. quadrangular, linear; S.V. 
hnear-lanceolate, slightly arcuate, with produced and rather 
obtuse extremities; striz distinct, dilated at intervals into 
prominent ridges on the inner margin. Length :00405” to 
70053"; strie 26 in 001”. (Fig. 6: a, side view; 0, front 
view.) 

Marine. Dredged off Tenby, Rev. J. Guillemard. 

The outline of this species differs but slightly from that of 
Nitzschia amphioxys, w.s.; but that is decidedly a fresh-water 
species ; its extremities are more acutely lanceolate, and the 
valve more arcuate ; the striz also terminate in puncta or 
dots, stead of dilating into distinct bands, asin this species, 
which was dredged in five fathoms, at about five miles from 
the shore, and may be considered purely marine. The strongly 
curved inner margin, and slightly recurved obtuse extremities, 
as well as the peculiar thickened striz, separate it from 
N. vivax. 

The dark bands appear to arise from a thickening of the 
strie at irregular intervals, varying from the third to the 
first in succession, and extend on an average about one third 
of the breadth of the valve, being shorter at the centre 

VOL. VI. D 


24 ROPER, ON BRITISH MARINE DIATOMACE, 


and extremities, and rather above that length m the inter- 
mediate space. 


Amphora sulcata, Bréb.—Valves oblong, with truncate 
extremities; the entire surface covered with longitudinal 
bands, formed of short transverse strie. Length -00266” ; 
breadth -001”; striz 14 and 20 in ‘001” (fig. 7). 

Marine. Caldy, Pembrokeshire, Rev. J. Guillemard. 

This species differs from any figured in vol. i. of the 
‘Synopsis,’ and though it approaches in structure some of the 
peculiar forms described by Professor Gregory m vol. v. of 
the ‘ Microsc. Journal,’ I cannot refer it satisfactorily to either 
of the species he has figured. M. De Brébisson, in his 
‘Memoir on the Marine Diatomacez of Cherbourg,’ gives a 
figure and description of Amphora sulcata, which appears 
only to differ in being rather more elliptical than the present 
species. I have therefore adopted his appellation, rather than 
make a further addition to our long list of native species. It 
appears to be rare, as I have only at present met with a 
single specimen. 

It differs from A. costata in the absence of the distinct 
longitudinal coste and moniliform puncta, and from the 
extremities being truncate and not produced as in that 
species ; and from A. affinis, to which the outline of the valve 
more nearly approaches, by the peculiar structure of its longi- 
tudinal bands. 


Amphora membranacea (fig. 8 a and b). 

Brackish water. Pembroke Harbour. Barking Creek. 

This species occurs abundantly in the mud from Pembroke 
Harbour, but does not appear to be common in many other 
localities, and I meet with it but rarely in the Thames and its 
tributaries. I merely give a figure, as that in vol. i. of the 
‘Synopsis’ appears to be taken from a frustule shortly after 
self-division, and gives an erroneous impression of the full- 
grown valve. The longitudinal striz are so marked a feature, 
and the breadth between the central nodules so much greater 
than in the specimen figured by Professor Smith, that the 
form now given might readily be mistaken for a distinct 
species. Fig. 8 a@ may be considered as fairly representing 
the state in which 4. membranacea usually occurs. Fig. 8 6 
is a frustule in process of self-division. 


Cocconeis scutellum, var. y (fig. 9). 
Marine. Lyme Regis. 
I figure this species as a variety of C. scutellum, as at 


ROPER, ON BRITISH MARINE DIATOMACE. 25 


present I have only met with it in one marine gathering, in 
which, however, it is not uncommon. The valve is oval, with 
the nodule dilated into a stauros, and differs from C. scu- 
tellum, var. (3, in the fineness of the dotted striz, and peculiar 
ocelli or semi-oval markings cutting off a portion, on each 
side of the valve. Professor Smith informs me that in his 
opinion they belong to the connecting membrane, but they 
appear to be rather. a thickening on the inner surface of the 
cell-wall. This species of Cocconeis is 80 very variable in size 
and appearance, that without having specimens with the 
same peculiar structure from several localities, I think it 
better to consider it as a variety, though more extended 
observation may prove that it should be classed as a distinct 
species. 


Navicula liber, var. 3.—Valve oblong, contracted towards 
the rounded extremities ; striz faint, parallel, not reaching the 
central line. Length -0033" ; breadth -OOL” (fig. 10). 

Marine. Caldy, Pembrokeshire, Rev. J. Guillemard. 

Professor Smith having, in vol. ii of the ‘ Synopsis,’ 
Liha Ehrenberg’s Nav. amphigomphus as a cuneate variety of 

N. firma. 1 refer this species with little hesitation as a 
somewhat similar variation to the nearly allied marine form 
N. liber, from which it appears to differ only m having 
bluntly cuneate extremities, and rather larger space between 
the termination of the strize and the median line. . It is pro- 
bably synonymous with Ehrenberg’s N. dilatata of the 
‘Microgeologie,’ t. u, f. 10. 


Pleurosigma transversale, var. 3.—V alve elliptical, lanceolate, 
with acute extremities, and very slightly curved median line ; 
strice aoa Length -0032" to ‘004 ; breadth -0009” to -001” 
(ig. 11). 

Marme. Caldy, Pembrokeshire, and dredged off Tenby, 
Rev. J. Guillemard. 

The typical species of P. transversale is by no means 
uncommon in both the gatherings above alluded to, whilst 
the variety here figured is rather rare. The general outline 
and structure of the valve is, however, so similar to that 
species, that having only at present met with it in these 
gatherings from Tenby Bay, I figure it merely as a variety, 
though more extended observation may prove it to be a 
distinct species. The vaives are much broader in proportion 
to the length than in the typical species, the extremities are 
acute instead of obtuse, and the median line nearly straight 
instead of having a considerable curvature. The striation 
also is finer and more difficult to resolve, than in that species. 


26 


TRANSLATIONS. 


On the OssiricaTion of the PrrmorpIAL CARTILAGE. 
By A. Baur, of Tubingen. 


(Abstracted from Miiller’s ‘ Archiv,’ 1857, No. 4, p. 347.) 


A mricroscopicaL analysis of the changes which take place 
in the ossification of cartilage has two questions to resolve : 
First, in what way does the peculiar structure of osseous 
substance arise from the so widely different structure of car- 
tilage? and, secondly, im this process, im what relation do 
the elements of the cartilage stand towards those of the 
bone? The latter question especially, since it has become 
known that bone may be formed without any pre-existing 
cartilage, has acquired redoubled interest. 

The origin of all osseous substance, not previously car- 
tilage, must be referred to the ossification of a blastema, 
which, according to most observers, is to be regarded as of 
the same nature as that of connective tissue; it consists, 
that is to say, of a matrix as yet indistinctly fibrillated, in 
which are scattered simple rounded cells, identical with the 
primary formative cells of connective tissue—the future con- 
nective tissue corpuscles. It is easily perceived that the 
ossification of this blastema is effected simply by the deposi- 
tion of calcareous matter in its intercellular substance, owing 
to which it gradually, and without any distinct lne of limi- 
tation, assumes the character of the osseous basal substance, 
whilst the cells shoot out into the irregular bone-corpuscles. 
In this case, it is certain that no intermediation of cartilagi- 
nous elements takes place ; nor can any indication of a pre- 
vious opacity dependent upon calcareous particles be re- 
marked. The process, therefore, can only be described as a 
direct ossification of the connective tissue. 

The process of ossification in cartilage is more complex. 
In this case, a simple transformation of the substance does 
not take place, but simultaneously with it a total change of 
structure, in consequence of which it becomes difficult to 
trace the histological alterations. The most favorable objects 
for examination are, perhaps, thin transverse sections made 
in various directions through the ossifying border of the dia- 
physis of a foetal long-bone, in as fresh a condition as possible. 


BAUR, ON OSSIFICATION OF CARTILAGE. 27 


The processes, which have in part been long well known, 
which are here seen to precede the ossification, are as fol- 
lows: The cartilage-cells,.which were previously uniformly 
dispersed, assume a definite order, corresponding to the sub- 
sequent bony structure; in the cartilages of the long bones 
they dispose themselves in rows, which, in a transverse sec- 
tion, appear like rounded groups. At the same time the 
individual cells increase in size, their contents, at first opaque 
and granular, become transparent, and exhibit a large vesi- 
cular nucleated nucleus. This enlargement of the cartilage- 
cells is effected at the expense of the matrix, which is even- 
tually so much diminished in proportionate bulk, that the 
separate rows of cells are separated only by a thin layer of . 
intercellular substance, whilst the cells in each row are 
themselves in absolute contact. A deposition of earthy 
elements, in the form of an opaque, coarse- or fine-grained 
material, now takes place on the walls of these cartilaginous 
cavities or canals. This deposit of earthy matter “forms 
apparently the distinction between cartilage and bone, but 
the microscopical characters of bone are still wanting—the 
bone-corpuscles, that is to say, and a homogeneous matrix. 
The cartilage-cells as yet lie unchanged in the cartilaginous 
capsules incrusted with calcareous matter, and whose opacity, 
even, renders the tracing of their further metamorphosis 
difficult. This, however, in the next place, consists in the 
circumstance that each cartilage-cell becomes the seat of an 
endogenous cell-formation ; for in place of a single vesicular 
nucleus, which may already be regarded as a secondary cell, 
several ‘vesicles of the same kind make their appearance, 
which fill the parent-cell, and after its disappearance become 
free. It is this brood of cells thus corresponding to the 
nucleus of the cartilage-cells, which constitute the contents 
of the calcified cartilaginous cavities, and become the start- 
ing point of all the subsequent changes. The fact, that in the 
ossification of cartilage an endogenous cell-formation takes 
place in the cartilage-cells—a process which is to be essen- 
tially distinguished from the multiplication of cartilage-cells 
by division, ‘such as is noticed in the growth of the cartilage 
before the commencement of ossification—has hitherto been 
adduced by all observers only in connection with the forma- 
tion of the medullary constituents of the bone, its import- 
ance as regards the origin of the bone itself not having been 
recognised. For whilst, in fact, part of this new generation 
of cells is transformed into blood-vessels, fat-cells, or indif- 
ferent medulla-cells, the peripheral cells, in apposition with 
the calcified cartilaginous capsules, are always surrounded 


28 BAUR, ON OSSIFICATION OF CARTILAGE. 


with a layer of soft, streaked interstitial substance, which 
lines the interior of the cartilage-cavities. Of true bone- 
substance, no trace was, up to this stage, to be perceived. 
This is not formed until this time by the direct ossification 
of this blastema, that is to say, by the transformation of its 
cells into bone-corpuscles, and of its intercellular substance 
into a homogeneous, not granular, osseous matrix. Whence 
it is evident that the first bone-substance must make its 
appearance in the form of a tube imclosing these calcified 
cartilage-cavities, and which in a transverse section presents 
the appearance of a ring beset with a single series of bone- 
cells. This osseous cylinder now becomes thickened from 
within outwards, by the successive ossification of new layers 
of blastema, deposited m a similar manner to the first, so 
that each cartilage-canal is gradually more or less completely 
filled up with a system of concentric osseous lamelle. The 
uniform concentrically lamellated structure of the long bones, 
which ever exists, is thus explained by the circumstance, that 
in the interior of each medullary canaliculus, a successive 
formation of ossifying lamin takes place from the centre 
outwardly, exactly in the same way as in the formation of 
the cortical substance from the periosteum, it takes place 
from the periphery. 

From what has been said, it is apparent that the individual 
tubuli of newly formed bone-substance must at first be sur- 
rounded by calcified cartilage-substance, and be separated 
from each other. It is now generally admitted, as in fact 
appearances render probable, that the calcified matrix of car- 
tilage itself is gradually transformed into homogeneous bone- 
substance, either by the coalescence of the separate calca- 
reous particles into a homogeneous substance, or that these 
particles, being only a provisional calcareous deposit, are 
previously absorbed. Upon this point it may now be re- 
marked, that the granular earthy deposit at any rate dis- 
appears, but with it also the organic substance to which it 
belonged ; and that thus the already commenced resorption 
of the cartilaginous matrix continues also after the com- 
mencement of the deposition of calcareous matter, in order 
to make way for the new bone-substance. This may be 
proved by direct observation. If a portion of cartilage 
undergoing ossification be treated with dilute hydrochloric 
acid, and transverse sections be made at the proper place, 
parallel with the border of the ossification, on using a due mag- 
nifying power, the ring, consisting of a single layer, of yellow- 
ish, strongly refractive bone-cartilage, beset with opaque 
bone-cells, will be seen, sharply defined, and in strong con- 


BAUR, ON OSSIFICATION OF CARTILAGE. 29 


trast with the wholly colourless cartilaginous matrix sur- 
rounding it, and which has regained its transparency owing 
to the solution of the calcareous particles, a clear proof that, 
in this case, the two tissues are not in a Condition of con- 
tmuous transition, but simply in juxtaposition. Further on, 
the separate, occasionally thickened and laminated osseous 
rings are seen to become more and more closely approxi- 
mated, until, the mtervening layer of cartilage having en- 
tirely disappeared, they come into immediate contact. Thence 
it follows that the matrix of the primordial cartilage takes no 
part in the formation of the bone-substance, but that, on 
the contrary, notwithstanding the calcification, it undergoes 
absorption. This result, derived from observ ation, has been 
long rendered probable by the chemical ElnGene of these 
tissues, seeing that the diversity in chemical constitution 
between bone-cartilage and the hyaline cartilage-substance 
was opposed to the notion that the latter remained im a per- 
sistent form in bone. In explanation, therefore, of the pro- 
cess of ossification, we must assume either a chemical change 
or a molecular replacement of the one substance by the other. 
But from what has been stated, it is proved that this replace- 
ment is not one of a merely chemical, molecular nature, but 
histological. The organic basis of bone is no more anatomi- 
eally than it is chemically identical with the matrix of hya- 
line cartilage. The latter is incapable of true ossification ; 
its calcification’ is a process accompanying ossification, it is 
true, but one of an essentially different nature. 

The osseous substance which makes its appearance in car- 
tilage is a new formation in the cartilage-cavities, but it does 
not commence at once as such, its formation being preceded 
by that of a blastema, consisting of simple cells, and a soft 
intercellular substance. Now this blastema corresponds in 
every respect with the ossifying layer of the periosteum, and, 
like that, with immature connective tissue, and it should, 
therefore, be described as of the nature of connective tissue. 
Its ossification takes place by the calcification of the persis- 
tently homogeneous intercellular substance, and the transfor-’ 
mation of its cells mto bone-corpuscles. 

Thus, in cartilage also, ossification is preceded by a forma- 
tion of connective tissue—in this case effected through the 
cartilage-cells. Connective tissue is thus the only foundation 
of the formation of bone. We thus have a histogenetic 
demonstration of the chemical correspondence of the so- 
termed bone-cartilage with the collagenous tissues, and, in 
general, established the hitherto overlooked unity in the 
genesis of the osseous tissue, inasmuch as the formation of 


30 BAUR, ON OSSIFICATION OF CARTILAGE, 


the primary and secondary bone-substance is referred to one 
and the same process. 

The share taken by the cartilage-cells in the process of 
ossification, consists im this, that they are the parents of 
those cells which afterward surround the ossifying connective 
substance, and sprout out in a radiate manner to form the 
bone-corpuscles. Thus the cells of the primordial cartilage 
are never, as such, transformed into bone-colls. The num- 
ber, size, and arrangement of the two, are consequently by 
no means the same; it should rather be said, that all the 
bone-corpuscles of a lamellar system correspond to a single 
row of cartilage-cells in the bone. The bone-corpuscles do 
not make their appearance until after the cartilage cells have 
been destroyed in the production of secondary cells, so that 
any transition from one into the other will be sought for in 
vain. 

In sections, on the other hand, taken from slowly and 
imperfectly ossifying cartilage, appearances are not unfre- 
quently met with, showing the occurrence within the still 
visible contours of a cartilage-cell of only one, or of a few 
closely packed bone corpuscles. In this case, the production 
of secondary cells had been limited to a few, or of only one. 
The surrounding of the endogenous cells with ossifying con- 
nective tissue, took place while still within the parent cell; 
true bone-substance, therefore, is limited to the cireumfer- 
ence of the cartilage-cell, whilst the latter itself is surrounded 
by calcified (or, im rachitic boxes, by perfectly hyaline) car- 
tilage-substance. Appearances of this kind have given rise 
to the supposition, that the bone-corpuscles correspond to 
the nuclei of the cartilage-cells, or to the cells themselves, 
thickened by imternal deposit. This view, however, in the 
case of the ossification of fcetal cartilage, leaves us im the 
lurch, whilst the results here obtained permit us to arrive, m 
general, at a satisfactory explanation. The process of ossi- 
fication of the primordial cartilage has shown, on the one 
side, that the bone-substance is not only chemically identical 
with that of connective tissue, but can only be referred, his- 
togenetically, to the elements of that tissue; and, on the 
other, that the tissue of hyaline cartilage is incapable of direct 
ossification, smee it can be shown that neither its substance 
nor its cells, as such, remain in the synonymous elements of 
the bone. The proposition that a formation of bone is pos- 
sible out of cartilage, in the same way as it is out of con- 
nective tissue, by the deposition of calcareous salts in its 
matrix-substance, and the transformation of its morphologi- 
cal elements into bone-corpuscles, is thus contradicted, and, 


KOLLIKER, ON MUSCULAR FIBRE. 31 


at the same time, is the doctrine of the identity of cartilage 
with bone and connective tissue, deprived of one of its most 
important supports. 


K6.i1KeR on the Structure of Muscutar Fisre 
(‘Zeitsch. f. Wiss. Zool.,’ vol. viii, p. 311.) 


KOLuikeEr states in his recent examination of muscle, made 
with reference to certain observations by Leydig on the same 
subject, he has found that in recent muscular fibre, besides 
the contractile parts and the nuc/ez, an interstitial substance 
exists presenting peculiar morphological characters, and 
which would appear, in all probability, to play an important 
part in the physiological and pathological processes in muscle. 

If a portion of recent frog’s muscle be examined carefully, 
and with good glasses, in an indifferent medium, two con- 
stituents in the muscular fibre will be perceived : 

1. The contractile, transversely or longitudinally striped 
substance, and— 

2. Very pale rounded corpuscles imbedded in the con- 
tractile substance, and disposed in long linear tracts. These 
granular tracts exist throughout the entire thickness of the 
fibre, on the surface as well as more deeply, and are so nu- 
merous as apparently to constitute no inconsiderable element 
of the muscular fibre. They are most readily seen in the 
longitudinally striped fibres ; but even in these it is not easy 
to determine the true position of the particles, although it 
would seem from the appearances presented that the tracts 
are not continuous through the entire length of the muscle, 
but are subdivided into longer or shorter portions. In the 
transversely striped fibre, these molecules are rendered 
more evident on the addition of water. 

Kolliker notices also the formation of vacuolar spaces in 
the interior of muscular fibre, under the influence of dilute 
saline solutions—as for instance of sulphate of soda of 83—7 
per cent. ‘These vacuoles, which contain a clear fluid, are dis- 
posed in longitudinal series, apparently occupying the spaces 
in which the above-described granular tracts are disposed. 


SS KOLILIKER, ON MUSCULAR FIBRE. 


After other observations tending to disprove the existence 
of the minute canals supposed by Leydig to exist in muscular 
fibre, Kolliker says, “ with respect to the interstitial granu- 
lar tracts in the muscular fibre of the frog, that one thing 
in particular should be remarked,—that the opaque fat- 
granules, which are frequently noticed in frog’s muscle, origi- 
nate in a metamorphosis of the pale granules above described. 

These molecules, in chemical constitution, appear to differ 
but little from the contractile substance—they are merely 
of rather more difficult solution in caustic alkali, and more 
soluble in acetic acid. 

This interstitial granular substance would appear to exist 
in the muscular substance, perhaps, of all animals. It is 
particularly well developed in the muscles of insects, naked 
amphibia, the sturgeon, &c.; in the latter instance, however, 
the molecules in their normal condition were observed only 
in the pale-coloured muscles. In the reddish subcutaneous 
muscles they appeared to be replaced by series of fat-mole- 
cules, of far larger size, especially near the tendons, and 
giving the muscle a more peculiar character than is presented 
even in the muscles affected with the highest degree of fatty 
degeneration. 

In the mammalia and in man the interstitial granules are 
very delicate and pale; and they are distinctly recognisable 
only when in a state of fatty degeneration, in which state 
they exhibit, in a transverse section, an appearance like that 
seen in the muscles of the frog. 

As regards the physiological import of the interstitial 
granular substance, Kolliker throws out as a probable hypo- 
thesis, that the granular tracts in question originate directly 
in the disintegration of the fibrils, and represent the normal 
molecular change of the muscular substance. He admits, 
nevertheless, that this explanation is attended with many 
difficulties, and that other suppositions may be entertamed 
with apparently nearly equal justice. 

He sums up the results of his inquiries into the ultimate 
structure of muscle as follows : 

1. All muscular fibres contain a large number of well- 
marked, vesicular nuclei with nucleoli, which are either 
parietal and affixed to the sarcolemma (human), or uni- 
formly dispersed throughout the contractile substance (Am- 
phibia), or even, as in certain embryos, disposed in series in 
the centre of the primitive fasciculus (some muscular fibres 
of Amphibia.) 

2. Inthe case of the contractile substance of the muscular 
fibres, it appears to him, as regards the higher animals, most 


SCHLOSSBERGER, ON CRYSTALS IN CATERPILLARS. 33 


im accordance with nature to assume that they are composed 
of fibrils, the transverse segments of which may be recog- 
nised in the Amphibia as minute, closely approximated 
points. 

3 No amorphous connective substance between the fibrille 
can be shown to exist by the microscope; but, on the other 
hand, there exists between them, at greater or less distances, 
an interstitial substance of peculiar morphological character, 
represented by serially disposed, pale granules. 

4. These granules, which exhibit considerable power of 
resistance towards caustic alkalies and acetic acid, are seen 
in longitudinal views of recent unchanged musular fibre, or 
in fibre which has been treated with caustic alkali, in their 
natural relations; whilst, under treatment with acetic acid, 
they appear like delicate streaks not unlike nucleated fibres. 
In transverse sections of muscle, they always present the 
appearance of a closer or wider punctation. 

5. The well-known fat-granules of muscular fibre are 
manifestly genetically connected with the granular streaks ; 
and, in fact, the fat-granules in the pale muscles may often 
be at once perceived to originate in the pale granules. 

6. The lacunar system described by Leydig has no ex- 
istence. The larger lacune of Leydig are the altered nuclei 
of the muscular fibres, the smaller the changed interstitial 
substance. 

7. The physiological imports of the interstitial granules is 
at present anything but clear. Many considerations would 
show the probability of their beimg connected with. the 
normal molecular changes in the muscles, but at the same 
time other suppositions are conceivable. 


On the Crystats contained in the Ma.pPicHIaN Vesseis of 
Carrrpittars. By J. Scuiosspercer, of Tubingen. 


(From Miiller’s ‘ Archiv,’ 1857, p. 61.) 


In the Malpighian vessels of a caterpillar (Hichenspinne- 
raupe) the microscope showed the contents to consist of 
numerous, brilliant, and colourless crystalline corpuscles, of 


34 SCHLOSSBERGER ON CRYSTALS IN CATERPILLARS, 


very various sizes, although the largest were scarcely equal to 
the quadratoctahedra of oxalate of lime which occur in human 
urine. Most of these minute crystals were isolated; but 
here and there might also be remarked crystalline masses, in 
which the individual crystals were united by an amorphous 
or membranous connective material. The isolated corpuscles 
never presented more than one surface to view, which was for 
the most part quadratic, though in some cases having an 
oblong form. No octahedra could be observed. 

They were insoluble in water, alcohol, and ether, as well 
as in acetic acid, even after long standing or the application 
of heat. Treated with nitric acid, and subsequently moistened 
with ammonia, they exhibited no trace of the murexid colour. 
Dilute nitric or hydrochloric acids dissolved the greater part 
of them without effervescence ; the solution threw down a 
copious precipitate on the addition of ammonia, which was 
insoluble in acetic acid. When covered with sulphuric acid 
gas bubbles were evolved, and bundles of crystals of selenite 
shot out. When heated on platina-foil they turned brown 
without fusing, andtheneffervesced with acids. 

From the foregomg no doubt could be entertained that the 
granules consisted essentially of ovalate of lime, and it is 
certainly not without interest to find im the urme of man 
and of insects, in the latter of which the presence of uric 
acid had already been demonstrated, a second constituent 
common to both, and probably a derivative of that acid, viz., 
oxalic acid. 

When the crystals placed on the stage of the microscope 
were brought into contact with mineral acids they exhibited 
a very peculiar condition. A dark line appeared passing 
transversely across the entire face and dividing it into two 
halves, and frequently a second would be seen perpendicular 
to the former, so that the surface would be divided into four 
areas. Ultimately they also melted down from the borders, 
but frequently were only partially dissolved, an extremely 
minute granule or very thin plate, evidently of organic ma- 
terial, being left. When the crystals were cautiously heated, 
and then submitted to the microscope, many could be seen 
retaining their original form, but deprived of their brilliancy 
and transparency, and tinged of a yellowish colour. It must 
be left undetermined whether the bodies now described are 
to be regarded as true crystals or not rather as a sort of 
secondary crystals or incrustations. With respect to this, 
the author refers to the fact that m crystals of carbonate of 
lime formed in the animal body (as, for instance, otolites), 
for the most part, when dissolved, also leave a residue of or- 


SCHLOSSBERGER, ON CRYSTALS IN CATERPILLARS. 35 


ganic matter; not unfrequently, also, they are distinguished 
from mineral calc-spar by their curved surfaces. 

Whether the crystals in the Malpighian vessels of the 
caterpillar of Sphinx convolvuli, described by H. Meckel 
(Mull. ‘ Arch.,’ 1846, p. 44), and those noticed by Leydig in 
the renal canals of Bombyx rubi and Talus (Mull. ‘ Arch.,’ 
1845, p. 466), are chemically identical with those above 
noticed, cannot be determined, since neither author has com- 
municated any chemical details. The former describes the 
crystals in Sphynx convolvuli as quadrate pyramids, sometimes 
white, and sometimes constituted of two white and an inter- 
mediate red layer. The crystals noticed by Leydig were 
octahedrous, whence it is very probable that these also con- 
sisted of oxalate of lime. 


REVIEWS. 


A Monograph of the Fresh-water Polyzoa. By Guo. J. 
Auman, M.D., F.R.S., &c., Regius Professor of Natural 
History in the University of Edimburgh. 


To the well-known and invaluable series of Monographs 
by Alder and Hancock, Forbes, Baird, and Darwin, published 
under the auspices of the Ray Society, we have to announce 
the addition of the long-expected work of Professor Allman, 
on the ‘ Fresh-water Polyzoa, including all the known species, 
both British and Foreign.’ 

In this splendid addition to their publications, the Ray 
Society, as in the former, has done excellent service to natural 
history ; for whether we regard the intrmsic interest of the 
subject itself, the complete and exhaustive way in which it has 
been treated, or the beauty and fidelity of the illustrations, 
Professor Allman’s Monograph may well take rank among 
the most important contributions to zoological science that 
have appeared for many years. 

In the preface we are informed, if that were necessary, 
that the work contains the result of many years’ careful 
study, and that in its preparation no trouble has been spared 
to render it as complete as possible, the subjects of which it 
treats having been considered under every point of view of 
which they seemed susceptible—zoographically, zootomically, 
homologically, and historically. All the figures, we further- 
more learn, upon the eleven lithographic plates, have been 
drawn from nature, and contain careful representations of 
of every species seen by the author, and in every case a 
figure is given of the species, both coloured and in its natu- 
ral size and magnified. 

As the number of known species of “ Fresh-water Polyzoa” 
is very small—not amounting to more than twenty-one, 
twelve of which belong to one genus,—it is obvious, that had 
the work been limited to a mere zoographical description of 
them, its bulk would have been very inconsiderable. But of 
the 119 pages of which it consists, 75 are occupied with con- 
siderations involving the Polyzoa in general, though more 
especially directed to those which are peculiar to fresh water. 
It is needless to insist upon the greatly-increased value given 
to the work from this large portion of its contents, for, as 
remarked by Professor Allman, “ the Polyzoa constitute an 
exceedingly natural group, and possess great uniformity of 


ALLMAN, ON POLYZOA. 37 


structure ; and as the fresh-water species afford fine typical 
examples of the class, a work devoted to the anatomy of 
these will apply in all essential points to that of the entire 
class, while such points of structure as are peculiar to the 
fresh-water forms will only tend to illustrate and explain the 
structure of the marine ones; so that the present Mono- 
graph, in its anatomical relations, may be fairly regarded as 
a general treatise on polyzoal organization.” 

After a full discussion of the anatomy, physiology, and 
homologies of the Polyzoa in general, the author proceeds 
to the zoographical part of his subject, including the history 
and biblography of the Fresh-water Polyzoa—their habits, 
geographical range, and classification. To which succeed 
the diagnoses, synonymy, and natural history of the genera 
and species; thus completely exhausting the subject, and 
bringing our knowledge of it, in most essential particulars, 
up to the present moment. 

The classification of the Polyzoa adopted by Professor 
Allman will be apparent in the following tabular view of their 
orders and sub-orders : 


Orders. Sub-orders. 
Lophophore bilateral ; (Arms of lophophore free or 
mouth with an epistome. | obsolete. j Lornorea. 


PHYLACTOLASMATA | Arms of lophophore united at } Prices mien 

the extremities. ; 

Polypide only partially re-] UrnaTeLira 
tractile P (fresh-water). 


PALUDICELLEA 


tile ; evagination of tenta- (fresh-water). 


Polypide completely vente} 
cular sheath imperfect. 

Polypide completely retrac- 
tile ; evagination perfect ; | CycLostoMaTA 
orifice of cell destitute of { (marine). 


GYMNOLAMATA. . moveable appendage. 


Polypide completely retrac- 
tile; evagination perfect ; | 
a circle of sete attached to Crenostomata 
the invertible portion, and { (marine).4 
acting as an operculum in | 
the retracted state. 2 


tile; evagination perfect ; 
orifice of the cell with a 
moveable lip. 


CHEILOSTOMATA 
(marine). 


Polypide completely at 


38 ALLMAN, ON POLYZOA. 


An arrangement which appears to us to be very natural and 
convenient. The definitions, however, of the marine gymno- 
leematous sub-orders do not include certain characters perhaps 
fully as important as those here given. The Cyclostomata are 
distinguished from the Cheilostomata, as much by the ter- 
minal position of the orifice of the cell, as by its bemg unfur- 
nished with a moveable lip or operculum; and from the 
Ctenostomata, not more by the absence of the fringed or 
setose margin to the orifice of the cell, than by the cir- 
cumstance that in them the cells arise by gemmation one 
from the other, as do those of the Cheilostomata, whilst in the 
Ctenostomata, or, as perhaps they might move appropriately 
be termed, the Crossostomata, the cells arise each separately 
from a common tubular stem, with whose cavity that of 
the cell communicates. The sub-terminal position of the 
orifice of the cell appears to be an essential characteristic 
of the important and numerous group of the Cheilo- 
stoma. 

The terminology employed by Professor Allman in the 
description of the Polyzoa, differing from that heretofore 
used, which has been very confused and unsatisfactory, 
demands attention, inasmuch as, with perhaps the exception 
of one term, it seems to us highly desirable that it should be 
generally adopted. The retractile portion or zooid, he terms 
“ nolypide ;” to the common dermal system of a colony— 
often erroneously termed ‘ polypary” and “ polypidom”’—he 
apples the term “ coencecium ;” this part consists almost 
universally of two perfectly distinct tunics — the outer 
of which is the “ ectocyst,’ whilst the internal is termed 
“endocyst.” The sort of disc or stage, which surrounds 
the mouth and bears the tentacula, is called the ‘“ lopho- 
phore,’ whilst the “epistome” is a peculiar valve-like 
organ which arches over the mouth in most of the fresh- 
water genera. The “ perigastric space” is the space included 
between the walls of the endocyst and the alimentary canal. 

The canecium is composed of the little chambers, or “cells,” 
in which the polypides are lodged, whilst that part of the ced/ 
through which they protrude is the “ orifice.” 

With reference to these terms, we would observe, that the 
term polyzoary, or in Latin, polyzoarum, which we have 
elsewhere employed, appears to us to be more likely 
to receive popular acceptation than the more recondite 
word, cenecium. 'The terms “ ectocyst” and “ endocyst,” 
though strictly applicable and highly appropriate nearly 
throughout the Polyzoa, must, when employed in the descrip- 
tion of the Ctenostomata, be somewhat strained when used to 


ALLMAN, ON POLYZOA. 39 


signify the outer and inner membranes of which the tubular 
portion of the polyzoary is composed. With respect to the 
composition of these membranes, a full description is given 
of the structure of the endocyst, which may be observed most 
favourably in Lophopus crystallinus. In this species it is com- 
posed of large, irregularly-shaped cells, filled with a colourless 
and transparent fluid. The mode of formation of these cells 
may be satisfactorily followed. 

It would seem, from some appearances noticed by Pro- 
fessor Allman, that the endocyst is pervaded by a system of 
canals of extreme delicacy, which constitute an irregular 
network in its substance; a curious and important fact, if 
confirmed by further observation. 

The ectocyst appears m every case to be absolutely struc- 
tureless, and the presence of cellulose could never be detected 
in it. The reactions of the pergamentaceous ectocysts of 
Plumatella are in favour of this tissue being composed of 
chitine. The “ ectocyst,’ therefore, it 1s observed, of the 
Polyzoa would seem to differ—at any rate, chemically—from 
the test of the Tunicata. 


In the account of the digestive system, an elaborate 
account is given of the histological structure of the alimen- 
tary canal, which is somewhat complex. <A curious peculi- 
arity appears to characterise the alimentary canal in the 
phylactoleematous Polyzoa, as distinguished from that in the 
marine gymnolemata—the absence, viz., of cilia in any part 
of its tract, except at the mouth and upper portion of the 
cesophagus. 


Ina note appended to the “Account of the Organs of Respi- 
ration and Circulation,” a full account is given of the anatomy 
of Pedicellina. This contribution to our knowledge of this 
curious and aberrant form of Polyzoa is of great mterest. 

The account given by Professor Allman of the generative 
system, reproduction, embryology, gemmation, and develop- 
ment in the Polyzoa is very complete and satisfactory. We 
have here a full description of the curious mode im which the 
different stages of the process of development of the embryo 
are carried out, and from the account given; it would appear 
that the external part of the embryonic sac becomes eventu- 
ally the ectocyst of the future adult Polyzoon. The develop- 
ment of two polypides in each embryonic sac, except in the 
case of Plumatella fruticosa, is a remarkable fact, with which 
—as, indeed, with the curious process of development alto- 
gether—we were previously unacquainted. 

VOL. VI. E 


Ad) ALLMAN, ON’ POLYZOA. 


A remarkable peculiarity, as it would seem, of the fresh- 
water phylactolematous Polyzoa, is the occurrence within the 
perigastric space, at certain seasons, of loose bodies of a 
peculiar nature. For these bodies, formerly confounded with 
ova, Professor Allman proposes the term “ statoblasts.” 
Their form is not exactly the same in the different species, 
but they may generally be described as lenticular bodies, 
varying, according to the species, from an orbicular to an 
elongated oval figure, and inclosed in a horny shell, consist- 
ing of two concavo-convex discs, united by their margins, 
where they are further strengthened by a ring which runs 
round the entire margin, and is of a different structure from 
the disc. In Cristatella and Pectinatella, the statoblast is 
furnished, when mature, with hooked spines. In all species 
the disc is of a deep brown colour, and would seem to be 
composed of a single layer of hexagonal cells. In the 
annulus the cells are larger, and filled with air, so as to sup- 
port the statoblast on or near the surface of the water. 

When placed in circumstances favouring their develop- 
ment, the statoblasts open by the separation of the two faces, 
and there then escapes from them a young Polyzoon, already 
in an advanced stage of development. 

These curious bodies have always been viewed and de- 
scribed as the ova of the Polyzoon, an error formerly partici- 
pated in by the author himself, who is now, however, and 
since the discovery of the true ovary, convinced that they 
are a peculiar form of bud, and must on no account be con- 
founded with genuine ova. 

The statoblasts, moreover, are not developed in the situa- 
tion of the true ovary, which appears in all cases to be situ- 
ated on the side and towards the upper part of the cell, 
though sometimes also connected with the stomach by means 
of a slender cord or funiculus, whilst the statoblasts are 
formed in or upon a similar funiculus or cord, which passes 
from the fundus of the stomach to the bottom of the cell, 
and upon which the testis, or male part of the generative 
system is developed. 

In two species of fresh-water Polyzoa, Plumatella emargi- 
nata and Alcyonella Benedeni, Professor Allman states that 
he has observed, besides the ordinary statoblasts, another 
kind, distinguished by some peculiarities. Whilst the ordi- 
nary statoblasts, towards the end of summer, may be observed 
lying loose in great numbers in the cavity of the cell, the 
peculiar kind in question “never lie loose in the cell, but are 
invariably attached to the internal surface of the walls, to 
which they are attached by a structureless cement.” After 


ALLMAN, ON POLYZOA. 41 


the decay of the coencecium, these attached statoblasts, which 
seem to have been noticed under similar circumstances by 
Dumortier and Van Beneden, may be seen adherent to the 
stone or other body on which the specimen had developed 
itself, and to which they are now connected in lines through 
the medium of a portion of the old cell in which they had 
been produced. The development and product of these 
attached statoblasts do not appear to have been as yet 
noticed. 

The true nature of these curious reproductive bodies is 
not very evident. Professor Allman regards them as being 
manifestly of the nature of a bud, or gemma, peculiarly 
encysted, and destined to remain for a period quiescent, or 
in a pupa-like state. 

He then proceeds to notice some points of comparison 
between these bodies and the so-termed winter-eggs in the 
Rotifera and ephippial ova of Daphnia, which, it is to be 
observed, however, have been shown by Mr. Lubbock to be, 
not gemme, but true ova, produced in the ovary, though 
possibly without the aid of male impregnation. 

It deserves remark, with respect to these bodies, that 
nothing of a similar kind has yet been noticed in any of the 
marine Polyzoa. The phenomenon, therefore, of their pro- 
duction in the fresh-water forms only, would seem to belong 
to the now long category of similar occurrences in other 
inhabitants of fresh water, whose continued existence in case 
of drought, and perhaps of extreme cold and other casualties, 
is provided for by the existence, at certain seasons, and under 
certain conditions of the so termed winter ova in the case of 
animals, and of hypnospores in the case of numerous alge. 
In this point of view, therefore, mere external resemblance, 
which would necessarily in some cases flow from their being 
destined to fulfil a similar office, need not be taken, as 
remarked by Professor Allman, in comparing the statoblasts 
of the Polyzoa with the ephippial ova of Daphnia, to indicate 
a greater share of significance in this resemblance than it 
really deserves. 

Professor Allman’s views, with respect to the whole subject 
of reproduction in the Polyzoa, are of high interest, and the 
more especially, as he states, with respect to the so termed 
“law of alternation of generation.” We will, therefore, 
transcribe what he says on this point: 


“ We have first, as the immediate result of the development of the ovum, 
a ciliated sac-like embryo, resembling in form and habit an infusorial ani- 
malcule: it is a non-sexual zooid. From this is produced subsequently, by 
a process of gemmation, another form of zooid, namely, the polypide, with 


42 ALLMAN, ON POLYZOA. 


a much more highly differentiated structure, in which the organs of diges- 
tion especially hold a dominant position, and which we may regard as sexual 
or non-sexual, according to the view we take of the relation between it and 
the testis. 

“ Now, if the formation of the ovary be attended to, it will be seen that 
this body is developed at a late period from the walls of the original sac- 
like embryo, which have undergone slight changes, and have become the 
endocyst of the more mature Polyzoon; and it will be at once perceived 
that this development of the ovary takes place in a way which may obviously 
be compared with the formation of a bud ; that, at least in Alcyonella, it 
occupies exactly the position in certain cells that the buds destined to 
become polypides do in others, and that at an early stage of polypide and 
ovary it is scarcely possible to distinguish one from the other; so that the 
idea is immediately suggested, that the body here called ovary is itself a 
distinct zooid, in which the whole organization becomes so completely sub- 
ordinate to the reproductive function as to be entirely masked, and appa- 
rently replaced by the generative organs. This would then constitute a 
third zooid, which would therefore be a sexual zooid; it is, however, 
unsexual (female). 

“Tn the next place, we find that upon the funiculus (in Aleyonella), which 
probably belongs rather to the polypide than to the endocyst, there is 
developed the mass described as a testis. Now, if we view this mass as a 
mere organ of the polypide, we must then regard the latter as the second 
sexual or male zooid; but the testis may perhaps be more correctly con- 
sidered like the ovary, as a distinct sexual bud, having the generative 
system so enormously predominant as to overrule and replace all the rest 
of the organization; this bud, like the ovary-bud, being also unsexual, but 
with a male function. In confirmation of this view, it is to be remembered 
that the funiculus has the power of giving origin to a very remarkable form 
of undoubted bud—the statodlast, which, until ulterior development is 
excited in it, has no nearer resemblance to an ordinary polypide bud than 
the testicular mass has; and to this statoblast—so far, at least, as position 
is concerned—the male bud or testis in Alcyonella would therefore be re- 
ig just as the female bud or ovary is related, to an ordinary polypide- 

ud. 

“Tf the above be the correct view, the complete comprehension of the 
Polyzoon will involve the conception of a ciliated sac-like embryo as a 
starting-point, and a series of buds, of which the last term will consist of a 
pair of sexual buds, the others being non-sexual; from the sexual buds a 
true embryo like the first is again produced, which affords the point of 
departure for another similar cycle.” 


The chapter on the “ Homologies of the Polyzoa” contains 
much matter of considerable interest, and the views, in 
many particulars original, therein advocated, are ably stated, 
whilst the entire subject is very fully and satisfactorily dis- 
cussed. Professor Allman adopts the opinion of those who 
see in the tentacular crown of the Polyzoa the represen- 
tative of the branchial sac of the Ascidians, with the im- 
portant modification, however, that it is the transverse 
and not the longitudinal bars of the branchial sac that are 
represented by the tentacles. But as his reasons for the 
adoption of this opinion, with which we are disposed to 
agree, would require to be given at considerable length to be 


BEALE, ON THE MICROSCOPE. 43 


rendered clear, we will not here detail them. Nor, with 
regard to our limits, can we enter upon several other points dis- 
cussed in this valuable chaper, which is essential to be studied 
by all who would make themselves acquainted with the va- 
rious opinions entertained upon the general homologies of the 
Mollusca. 

Having thus noticed, at considerable length, the more 
general part of Professor Allman’s work, we can further merely 
state, that it afterwards proceeds: 1. To the history and bib- 
hography of the subject ; 2. To the geographical distribution 
of the Fresh-water Polyzoa; with respect to which, it is re- 
marked as a surprising circumstance that not a single species 
has been found beyond the limits of the north temperate 
zone, not one having been recorded as occurring south of 
the Mediterranean in the old world, or of Philadelphia in the 
new. And this limited distribution is the more remarkable, 
since some species are found at an elevation of 6,500. 


The succeeding portion of the work is devoted to an 
account of the various genera and species. 


How to work with the Microscope. By Lioneu 8. Beare, 
M.B., F.R.S. London: John Churchill, 


Few men have worked more diligently and successfully 
with the microscope than Dr. Beale, and none have more 
claims to be heard on its uses and the methods of its appli- 
cation. Although we have had many works devoted to the 
microscope, to explanations of its structure, and the objects 
it investigates, we think with Dr. Beale that a book with a 
more thoroughly practical aim was really a desideratum. It 
is this hiatus in our literature which Dr. Beale has attempted 
in the present work to fill up. The imstruction conveyed is 
in the form of lectures, which were, in fact, delivered by the 
author during the winter session of 1856-7. He offers the 
following apology for his little book : 


“An earnest desire to assist in diffusing a love for microscopical inquiry, 
not less for the pleasure it affords to the student, than from a conviction of 
its real utility and increasing practical value in promoting advancement in 
various branches of art, science, and manufacture,—a wish to simplify as 
far as possible the processes for preparing microscopical specimens, and the 
methods for demonstrating the anatomy of different textures,—and the 


44: BEALE, ON THE MICROSCOPE. 


belief that many who possess microscopes are deterred from attempting any 
branch of original investigation solely by the great difficulty they experience 
in surmounting elementary detail and mere mechanical operations,—are my 
chief reasons for publishing this elementary course of lectures, which was 
delivered during the past winter.” 


We are sure many young workers, and many old ones too, 
will be glad to receive directions at Dr. Beale’s hands. The 
first lecture is devoted to that very important subject, the 
purchase of a microscope; and in future we shall refer our 
numerous correspondents on this point to Dr. Beale’s work. 
We might profitably insert the whole of this lecture, but as 
a specimen we give the author’s remarks on “ Students’ 
Microscopes :” 


“Mr. Salmon, Mr. Highley, and Mr. Matthews were, so far as I know, 
the first makers in London who brought out a really good, cheap, practical 
instrument, furmshed with foreign object-glasses. Mr. Highley’s pattern is 
now made by Mr. Ladd. 

“T would strongly recommend all who are about to purchase a student’s 
microscope to examine the instruments of these makers. I can also strongly 
recommend the educational microscope of Messrs. Smith and Beck, which, 
however, is somewhat more expensive, costing ten guineas with case. 

“The microscope made by Mr. Field, of Birmingham, which gained the 
medal at the Society of Arts, is, for the price, an exceedingly good instru- 
ment. It is provided with two eye-pieces, two object-glasses (magnifying 
from 25 to 200 diameters), bull’s-eye condenser forceps and a live box, and 
packed in mahogany case with this apparatus complete, costs only three 
guineas. 

“Those who wish for a microscope as perfect as it can be made in the 
present day I should advise to look at the beautiful instruments of Powell 
and Lealand, Ross, and Smith and Beck. I would also recommend those 
of Mr. Pillischer to attention. In alluding specially to these instruments I 
wish it to be distinctly understood that I do not in any way disparage the 
work of other and less celebrated makers, but having had some experience 
with those instruments to which I have directed your attention I feel it 
right to express an opinion upon them. 

“Tn chosing a microscope the following requirements should be borne in 
mind :— With reference to the optical part, the zzch object-glass should mag- 
nify not less than 30 diameters, and the quarter not less than 200, when the 
shallow eye-piece is applied. The field should be well lighted, and the lines 
of delicate objects submitted to examination should be sharp and well de- 
fined. The mirror should be large (at least two inches in Niamtetaed one 
side plane, the other concave, and it should be adapted to the body of the 
microscope in such a manner that very oblique rays of light may be made to 
impinge upon the object. 

** With regard to the mechanical portion of the microscope, the adjust- 
ments should work smoothly, and an object placed in the field for examina- 
tion should not appear to move or to vibrate when the screws are turned. 
The body should be provided with a joint, so that it may be inclined or 
Hices quite horizontally. The stage should be at least three inches in 
ength, by two and a half in width, and there should be a distance of at 
least an inch and a half from the centre of the opening in the stage over 
which the slide is placed, to the upright body. The motion of the slide upon 


BEALE, ON THE MICROSCOPE, 45 


the stage, and all other movements and adjustments, should be smooth and 
even, without any tendency to a jerking or irregular action. 

“ Necessary Apparatus.—Kvery student’s microscope should be provided 
with a neutral tint glass reflector for drawing and measuring objects, a 
diaphragm, to the under part of which is fitted a tube to receive an achro- 
matic condenser, or polarizing apparatus, a bull’s eye condenser, one shallow 
eye-peice, and two powers—a low one, magnifying from 20 to 40 diameters, 
and a quarter of an inch which magnifies at least 180 diameters. 

“These instruments should be conveniently packed in the case with the 
microscope. The polarizing apparatus and the achromatic condenser can be 
purchased afterwards. ‘lhe cost of the microscope without these instru- 
ments, but including the other apparatus mentioned, should not be more 
than from six to seven pounds ; and if the microscope be mounted upon a 
cast-iron foot instead of a brass one, it may be obtained for about a pound 
less, without its practical utility being in any way impaired.” 


The second lecture treats of illumination, of reflected light, 
transmitted light, and polarized light; also of artificial light 
and the drawing of microscopical specimens, and the mea- 
suring of objects. We give one extract on an important 
practical point, and which some otherwise competent obser- 
vers do not appear to have mastered : 


“* On Ascertaining the Magnifying Power of Object-glasses.—Permit me now 
to say a few words upon the magnifying power of the different lenses. 
Although the several object-glasses are termed one inch, one quarter of an 
inch, one eighth, &c., the magnifying power of each is not definite, and the 
quarters of some makers magnify many times more than those of others. 
It is well, therefore, that every observer should be able to ascertain for him- 
self the magnifying power of his different glasses. Suppose I wish to know 
how much this French quarter magnifies. The one-thousandth of an inch 
micrometer is placed in the field, and the magnified image is thrown by 
means of the neutral tint glass reflector upon this scale, divided into inches 
and tenths of inches. The magnified one-thousandth of an inch covers about 
two-tenths of an inch, and consequently this glass magnifies about 200 
diameters; for if it covered one inch, the thousandth of an inch must have been 
magnified 1,000 times, but in this case it only corresponds to the one-fifth 
of an inch, and therefore the one-thousandth is magnified 200 times. For 
lower powers the one-hundredth of an inch scale may be employed. The 
manner of ascertaining the magnifying power is therefore exceedingly sim- 
ple; but it is very important for the observer to know the magnifying 
power of every lens, and he should ascertain this before he commences te 
make any observations.” 


The third lecture is devoted to the instruments required in 
addition to the microscope in various minute investigations. 
Scissors, balsams, cements, glasses, preservative solutions, 
and other things are treated of in this lecture. The fourth 
lecture is devoted to instructions for making cells for micro- 
scopical preparations. This is a very important art, and will 
save a good deal of expense to those who keep collections of 
specimens. We would, however, warn those who have but 
little time to spare against being too anxious to make every- 


46 BEALE, ON THE MICROSCOPE. 


thing for themselves. The observation of nature accurately 
should be the great object to which all who possess micro- 
scopes and intelligence should aim. At the fifth lecture we 
get to work in earnest. The apparatus is all prepared— 
cements, preservative fluids, cells—and now the objects are to 
be examined. 

The following remarks on the importance of examining 
the same objects in various ways are sound, and the illustra- 
tions judicious : ~ 

“Many objects require examination in several distinct ways before an 
accurate idea of their general structure can be obtained. It is in many 
instances of the utmost importance to examine a body by reflected light as 
well as by transmitted light, and to observe the peculiarities of structure 
when it is surrounded with ar, or immersed in water, or in a highly refract- 
ing fluid, such as glycerine, oil, turpentine, or Canada balsam. Not less 
valuable is the information we derive from the application of certain chemical 
reagents, to the consideration of which I shall devote some time in a future 
lecture. ‘The microscopical observer must, however, feel that in order to 
make out the exact nature of any texture it is necessary to subject it to 
various different processes of observation, and to the action of certain chemi- 
cal reagents, according to the ¢ransparency or opacity, density, refractive power, 
and chemical composition of the specimen. So also he must submit the 
object to examination with high powers and low powers. 

“Appearance of the Same Olject examined in Air, Water, and Canada balsam, 
by Transmitted Light, and under the influence of Reflected Light and Polarized 
Light.—Under these five microscopes have been placed specimens of the 
same structure (spherical crystals of carbonate of lime) magnified in the 
same degree. 

“In Air,—In the first they are shown by transmitted light in air mounted 
in the dry way, and you will notice how very dark and thick their outline 
appears, and how impossible it is to make out the ultimate arrangement of 
the crystalline mass. 

“In Water.—In the second microscope the crystals are seen in water. 
The outline is still very dark and thick, but a few lines may be observed 
radiating from the centre of the crystals towards their circumference, 
although not very distinctly. 

“In Canada Balsam.—In the third microscope the crystals are shown im- 
mersed in Canada, balsam, Here the outline appears as a sharp well-defined 
line. A vast number of narrow lines are seen radiating from the centre of 
the crystals towards its circumference, which shows that it is really made 
up of a congeries of minute acicular crystals, 

“ By Reflected Light.—In the fourth microscope the crystals may be exa- 
mined by reflected light. Their globular form, and yellowish colour, are very 
distinctly seen, and you may observe that the surfaces of the crystals 
generally are slightly rough, while some appear to be covered by minute 
elevations. 

“ By Polarized Light.—Under the fifth microscope another preparation of 
the crystals is seen under the influence of polarized light. Each erystal 
exhibits a black cross which alters its position and appearance as the 
analyzer is rotated. These important points might be illustrated by a vast 
number of other substances, and I cannot advise you too strongly to subject 
various microscopical structures to exammination in air, water, and Canada 
balsam, and by direct or fais as well as under the influence of trazsmitted 
light, and in some cases by polarized light.” 


land 


BEALE, ON THE MICROSCOPE. 47 


The seventh lecture is devoted to the examination of tis- 
sues, and their preservation as permanent objects. Although 
the preservation of specimens is undoubtedly secondary to 
the accurate observation of facts, every microscopist must 
find it advantageous to keep specimens for reference, and 
where systematic teaching in histology is the object, it can 
scarcely be effected at all without a good collection of speci- 
mens. Hence the value of this lecture. The succeeding 
lecture is devoted to the same subject ; the method of pre- 
paration being that of injection. On this subject Dr. Beale 
is an authority. He has been so successful in injecting the 
ducts of the liver, that we give his experience on this subject : 


“The modes of injecting which we have just considered, although appli- 
cable to the injection of vessels, are not adapted for injecting the ducts and 
glandular structure of glands; for as these ducts usually contain a certain 
quantity of the secretion, and are always lined with epithelium, it follows 
that when we attempt to force fluid into the duct, the epithelium and 
secretion must be driven towards the secreting structure of the gland, which 
is thus effectually plugged up with a colourless material, and there is no 
possibility of making out the arrangement of the parts. In such a case it 
is obviously useless to introduce an injecting fluid, for the greatest force 
which could be employed would be insufficient to drive the contents through 
the basement membrane, and the only possible result of the attempt would 
be rupture of the thin walls of the secreting structure and extravasation of 
the contents. As I have before mentioned, partial success has been obtained 
by employing mercury, but the preparations thus made are uot adapted for 
microscopical observation. 

**T have long felt very anxious to inject the ducts of the liver in order to 
ascertain the manner in which they commenced in the lobule, and the 
precise relation which they bore to the liver cells. This has long been a 
point of dispute among microscopical observers, and many different and 
incompatible conclusions have been arrived at by different observers. In 
order to prove the point satisfactorily it was obviously necessary to inject 
the ducts to their minute extremities, which no one, as far as I was able to 
ascertain, had succeeded in doing satisfactorily. After death the minute 
ducts of the liver always contain a little bile. No force which can be em- 
ployed is sufficient to force this bile through the basement membrane, for it 
will not permeate it in this direction. When any attempt is made to inject 
the ducts, the epithelinm and mucus, in their interior, and the bile form 
an insurmountable barrier to the onward course of the injection. Hence it 
was obviously necessary to remove the bile from the ducts before one could 
hope to make a successful injection. It occurred to me, that any accumu- 
lation of fluid in the smallest branches of the portal vein or in the capillaries, 
must necessarily compress the ducts and the secreting structure of the liver 
which fill up the intervals between them. The result of such a pressure 
would be to drive the bile towards the large ducts and to promote its 
escape. Tepid water was, therefore, injected into the portal vem. The 
liver became greatly distended, and bile with much ductal epithelium flowed 
by drops from the divided extremety of the duct. The bile soon became 
thinner owing to its dilution with water which permeated the intervening 
membrane, and entered the ducts. These long, narrow, highly tortuous 
channels were thus effectually washed out from the point where they com- 


48 BEALE, ON THE MICROSCOPE. 


menced as tubes not more than 1-3000th of an inch in diameter, to their 
termination in the common duct, and much of the thick layer of epithelium 
lining their interior was washed out at the same time. The water was re- 
moved by placing the liver in cloths with sponges under pressure for twenty- 
four hours or longer. All the vessels and the duct were then perfectly 
empty and in a very favourable state for receiving injection. 'The duct was 
first. injected with a coloured material. Freshly precipitated chromate of 
lead, white lead, vermilion, or other colouring matter may be used, but for 
many reasons to which I have alluded, the Prussian blue injection is the 
one best adapted for this purpose. It is the only material which furnishes 
good results when the injected preparations are required to be submitted to 
high magnifying powers. Preparations injected in this manner should ke 
examined as transparent objects.* They may be mounted in the ordinary 
penne fluids or in Canada balsam, but glycerine forms the most satis- 
actory medium for their preservation. A specimen of the ducts injected in 
this manner has been placed under the microscope, and specimens of the 
portal vein, of the ciliary processes, of the choroid, of the kidney, and some 
other tissues injected with the Prussian blue mixture, have been arranged 
for examination.” 


The last lecture is devoted to the advantages of chemical 
reagents im microscopical investigation. Here again we 
meet Dr. Beale on ground peculiarly his own. There can be 
no doubt that the necessity for a tedious chemical investiga- 
tion may be often avoided by the application of reagents to 
microscopic objects. Indeed, in some cases, where objects are 
altogether too small for chemical analysis in the laboratory, 
their composition may be known by observing the action of 
reagents under the microscope. As an instance of the value 
of the instructions in this part of the work, take the fol- 
lowing : 


“Testing for Carbonate and Phosphate of Lime, Phosphate of Ammonia-and- 
Magnesia, Sulphates and Chlorides—Now suppose I wish to ascertain the 
nature of the substances composing this earthy matter. I take a small por- 
tion, about the size of a pin’s head, place it upon this slide, and cover it 
lightly with a peice of thin glass. Next, I expel a drop of nitric acid (by 
warming in the hand the bottle with the capillary neck) close to the thin 
glass. The acid soon reaches the sediment, and now, one may observe the 
disengagement of a few bubbles of gas, which are, as it were, temporarily 
pent up by the thin glass, and prevented from escaping. If there should be 
any doubt of the action of the acid, we may resort to examination in the 
microscope, when, if there be very few bubbles, they may be detected. In 
this deposit carbonates are present. 

“The acid solution is now neutralized with ammonia. A faint flocculent 
precipitate is produced. After this has stood still for a few minutes it is 
covered with thin glass and examined under the microscope. It will be 
seen to consist of amorphous granules (Phosphate of Lime) and small 
crystals, which, if alowed to stand long enough, will take the form of trian- 
gular prisms (Phosphate of Ammonia and Magnesia). 

“If we wish to ascertain the presence of sulphates, a little of the nitric 


* “On the Anatomy of the Liver of Man and Vertebrate Animals.’ 
London: John Churchill, 1856. 


HIS, ON THE CORNEA. 49 


acid solution is treated with zitrate of Barytes. An amorphous precipitate 
of Sulphate of Baryta, insoluble in strong acid and alkalies, takes place, if 
sulphurie acid be present. The presence of chlorides is detected by the 
addition of a little xi¢rate of silver to a drop of the solution of the deposit in 
weak nitric acid. The white precipitate of chloride of silver is insoluble in 
nitric acid, but it is dissolved by ammonia. 

“These will serve as examples of the method of detecting the presence of 
different substances in a very minute quantity of matter. The indications 
obtained in this manner are quite as valuable, and may be relied on with as 
much certainty, as if we were provided with avery large quantity of material 
to work upon; in a single drop of a composite solution, the presence of 
several different acids and bases may be detected.” 


The work concludes with a series of tables for practising 
the use of the microscope and manipulation, with a sort of 
catalogue raisonné of apparatus required in microscopical 
investigation. Dr. Beale’s book will be found an admirable 
assistant to all who have made some little progress in micro- 
scopic investigations. 


Beitrége zur normalen und pathologischen Histologie der 
Cornea. Von Dr. WitHELM His. 1856. 


Contributions to the normal and morbid Histology of the Cornea. 
By Dr. W. His. 


Ir the results arrived at by Dr. His in this unassuming 
little work are confirmed by future observers (and the whole 
style and manner of working of the author lead us to 
entertain a strong expectation that they will be), it will 
prove to be one of the most valuable ‘ Contributions’ which 
has been made for a long time, not only to normal and mor- 
bid histology, but to physiology. For one of the most im- 
portant problems presented to the physiologist at the present 
moment is, what is the influence of conditions upon nutri- 
tion? or, in other words, how far and in what manner can 
the vital activities of the elementary histological components 
of tissues be checked, excited, or otherwise modified by 
influences from without? It is from their bearing on this 
great question that Dr. His’s inquiries appear to us to de- 
rive their preponderant interest, though there are many 


50 HIS, ON THE CORNEA. 


other points of view in which they are eminently worthy of 
attention. 

The cornea is particularly well fitted for this class of inves- 
tigations, from its transparency, its thinness, and that marked 
peculiarity of structure which enables abnormal alterations 
to be so easily detected. At the same time the absence of 
any vascular network throughout the greater part of its sub- 
stance has the great advantage of freeing the mind of the 
inquirer into the essence of the earlier stages of its alteration, 
from the thraldom of that “action of the vessels” hypo- 
thesis, so long the deus ex machind of British physiologists 
and pathologists. 

The structure of the cornea has been a matter of much 
controversy among histologists. It has been affirmed to be 
composed of superimposed lamelle, the number of such 
lamelle varying, according to the describer, from four to two 
hundred. Some have supposed these lamellz to be glued 
together by an invisible cement; others have been led to 
conceive that interspaces, the “corneal tubes,” normally 
exist between the lamelle ; another school of observers has 
denied the existence of lamelle altogether, maintaining that 
the cornea is composed of interlaced fibres. Some have 
asserted that the cornea is fitted into the sclerotic as a watch- 
glass into its frame; others, on the contrary, affirm that the 
tissue of the one is continuous with that of the other. Be- 
fore giving an account of Dr, His’s view we must describe 
his mode of operation—an essential element in questions of 
this kind. 

The cornea may be examined either with or without pre- 
vious preparation. In the latter case the one thing needful 
is, that the sections, whether vertical or horizontal, be made 
with an extremely sharp scalpel, and at one draw, without 
sawing. A good vertical section should not be broader than 
the thickness of the cornea, and should be examined without 
a covering glass. Without these precautions the natural 
appearance undergoes great and immediate alteration. 

Pure and colourless dilute pyroligneous acid (Dr. His 
unfortunately does not give the precise strength) is the best 
preservative and hardening agent ; but the preparations must 
not be exposed to the sun or they become brown and opaque. 
Sections of extreme thinness can readily be cut from cornez 
hardened in this acid. 

Dilute hydrochloric and sulphuric acids (in equal propor- 
tions of acid and water) are of great service, asmuch as 
they destroy the intercellular substance, and leave the cor- 
neal cells, vessels and nerves. A drop or two of either of 


HIS, ON THE CORNEA. 51 


these acids may be added to a section after it is covered, and 
will be found, after a few hours, to have done its work with- 
out disturbing the relations of the unattacked parts. 

Pursuing these various modes of investigation, and using 
the one as a check upon the other, Dr. His has arrived at 
the following results. 

The cornea and the sclerotic are, as has for some time been 
maintained by the most trustworthy observers, perfectly con- 
tinuous ; the tissue of the latter gradually passing into that 
of the former organ, but assuming a more regular arrange- 
ment, and appearing lamellate instead of areolar. The ele- 
ments of the cornea appear to be arranged circularly at the 
margin of both its most superficial and its deepest layers, 
crossing one another towards the centre. In the interme- 
diate substance, on the other hand, or middle layer of the 
cornea, the disposition is radial. 

Anteriorly the cornea appears to be bounded by a. struc- 
tureless layer—the “anterior elastic lamine” of Bowman ; 
posteriorly is a similar but thicker stratum—the well-known 
membrane of Demours or Descemet. The latter is easily de- 
tached, but the former cannot by any procedure be cleanly 
separated from the subjacent tissue. In fact, it would appear 
that the intercellular substance of the cornea passes at 
intervals completely into the anterior elastic lamina, thus 
constituting the “fibrous cordage” of Bowman. Dr. His 
says— 


“ Approximating to Reichert’s view, I am inclined to think that the anterior 
lamina and membrane of Descemet both originate in a more abundant 
deposit of intercellular substance, which, projecting beyond the level of the 
strata of cells, subsequently becomes differentiated from the other inter- 
cellular substance. The membrane of Descemet becomes more differentiated 
than the anterior lamina; the latter constituting, as it were, a sort of 
transitional formation between the intercellular substance and Descemet’s 
membrane. As for the difference in point of separability between the 
membrana anterior and membrana Descemetii, it must be remembered, 
Ist, that the distinctness of the latter depends on circumstances, and that 
it can hardly be separated in a fresh eye without carrying away with it 
some portions of substantia propria; 2d, that the much more parallel 
lamination or cleavability of the deeper layers of the cornea, as compared 
with the superficial ones, greatly favours the more easy separation of the 
membrane of Descemet. ‘The anterior lamina becomes lost at the edge of 
the cornea, passing into a simple, sharply defined, dark line, which bounds the 
conjunctiva anteriorly. The anterior Jamina is not so universally present as 
the membrane of Descemet ; while I found it very beautifully developed in 
man, the ox, the sheep, the pig, the rabbit, and the Guinea pig, as well as 
in pigeons and rooks, I could not discover it in the horse, the goat, the 
dog, or cat. In the latter animals the epithelium lies directly upon the 
cellular substantia ropria, and the surface, when the epithelium is removed, 
appears uneven all drawn in, at those places where the ‘fibrous cordage’ 


52 HIS, ON THE CORNEA. 


is attached. In these animals vessels may run immediately beneath the 
epithelium, while in the others they are always covered by the anterior 
lamina.”’—pp. 11, 12. 


The constituents of the substantia propria are the cells and 
intercellular substance, which form a continuous whole. 
After discussing the various theories which have been enter- 
tained with regard to the normal and unaltered structure of 
the intercellular substance, Dr. His brings forward evidence, 
both embryological and histological, to show that neither 
lamelle nor fibrils, as such, exist in the cornea; but that it 
is a continuous substance which possesses a tendency to 
cleave with great readiness in particular directions—the 
planes of separation of the fibres and lamelle which are so 
readily produced artificially. The cornea, then, is laminated 
and fibrous only in the sense that wood or slate may be said 
to be so ; and it would be more proper to say that it possesses 
a lamellar or fibrous cleavage. In vertical sections of a 
fresh cornea prepared with the precautions described above, 
Dr. His asserts that “not a trace of lamellar or fibrous disin- 
tegration is visible,” p. 21. Dr. His, however, continues to 
use the word “lamelle” in the sense of “those portions of 
intercellular substance which are cleavable in one direction 
(the length of the lamella) ; and in speaking of the interlace- 
ment of lamelle all that is meant is, that at different levels 
the substance splits in different directions.” 

The corneal cells le between the lamellz, and send out 
processes between these last much as the osseous lacune send 
their processes between the lamelle of bone. Dr. His dis- 
tinguishes three forms of these cells—the stedlate cells, which 
are found throughout the greater part of the cornea ; those of 
the superficial layer of the cornea; and those of its marginal 
zone. ‘The first kind are flattened and typically quadripolar ; 
their processes branch out and anastomose abundantly, and 
they contain a single flattened “nucleus.” The superficial 
cells are like the stellate kind, much branched ; but the body 
of the cell and the nucleus are so very small that they appear 
almost like mere thickenings, and their processes form a very 
peculiar system of arched meshes, concave externally. From 
these peculiarities the superficial cells at first seem to con- 
stitute a network of curved fibres, and their true nature is 
only to be made out readily im young cornez or im those 
which are in an early stage of inflammatory alteration. 

The marginal cells lastly, are elongated and fusiform and 
their long terminal. processes commonly remain distinct and 
parallel for a great distance, so as to give rise to a false 
appearance of fibrillation in the intercellular substance. 


His, ON THE CORNEA. 53 


We must omit more than a passing reference to the chemical 
properties of the cornea; to its permeability by the aqueous 
humour ; and to its early structural condition ; on all of which 
points much valuable information is given by Dr. His. 

With regard to the nerves discovered by Schlemm, nearly 
thirty years ago, Dr. His states that, very soon after their 
entrance into the cornea they lose their dark contours and be- 
come pale and nucleated fibres. These fibres divide repeatedly, 
and at length anastomose with one another, so that their ul- 
timate termination here, at any rate, is in a nervous network. 
This is a very important fact, and one whose confirmation is 
highly desirable. The nerves are almost entirely confined to 
the anterior third of the thickness of the cornea, none at all 
apparently reaching its posterior half. In conformity with 
this anatomical fact, Dr. His found that im experimenting on 
rabbits the animals struggled violently when the heated wire 
which he employed came into contact with the cornea, and 
more especially as it entered its substance ; but that no further 
signs of pain were manifested as it passed from this point to 
the membrane of Descemet. 

Capillary vessels are commonly found to extend mto the 
human cornea for a distance of from half a line to a line from 
the margin; and it has been supposed that the corneal cells 
and their processes are hollow, and that they form a system 
of tubes communicating with one another and with these 
vessels. With regard to the first point, Dr. His decides in 
favour of the tubularity of the corneal cells and their 
processes —influenced. chiefly, as it would appear, by the 
results of touching the cornea of a rabbit or of a goat with 
nitrate of silver. The white spot which is immediately 
formed is found, on microscopic examination, to consist of 
granules of metallic silver, which are deposited only in the 
cells and their processes—the intercellular substance merely 
acquiring a slight brownish tinge. Furthermore, the deposit 
of metallic silver is not confined to those cells which are in 
the immediate vicinity of the spot touched, but is found in 
other and quite isolated ones. We cannot see in this curious 
experiment, however, any proof of the tubularity of the 
corneal cells and processes. If they were solid the same 
thing would occur, so long as they were capable of absorbing 
fiuid and contained more chlorides than the surrounding 
substance. 

On the other hand, im opposition to Coccius, Dr. His 
maintains that no communication exists between the cells 
and; the capillaries. And he conceives that the nutrition of 
the cornea is kept up not only by the vascular supply, but 


5A HIS, ON THE CORNEA. 


also by the aqueous humour, having shown experimentally 
that the cornea is permeable to the latter fluid. 

Such being the structure of the cornea, the author next 
inquires what are the changes which take place in that 
structure when some irritant adequate to produce inflam- 
matory action is applied to the part? The ordinary notion 
is, that the capillaries bordering the cornea throw out an 
exudation of plastic lymph into its substance ; and that this 
exudation, becoming more or less organized, gives rise to that 
obvious opaque substance which is the well-known ordinary 
consequence of corneal inflammation. In this, the current 
view of the inflammatory process, it will be observed that the 
tissue in which inflammatory action takes place is regarded 
as entirely passive, the inflammatory exudation being as much 
parasitic in the pre-existing tissue, as a mass of moculated 
cancer-cells would be, and wndergomg its changes as 
independently of everything but its feeders, the vessels. 

Virchow, however, has drawn attention to the circumstance 
that many so-called exudation-products are nothing but 
the local tissues metamorphosed ; and Dr. His’s investigations, 
carrying this idea further, tend to the conclusion that in 
ordinary traumatic keratitis the apparent exudation is entirely 
the product of a metamorphosis of the local tissues. 

This conclusion is so important, that it will be well to lay 
before the reader some of the details of the experiments 
on which it is based. The irritant employed by Dr. His in 
these investigations varied in character ; nitrate of silver, a 
hot wire, excision of small portions, the introduction of 
threads which were allowed to remain—but the results were 
always essentially similar. The irritant was invariably applied 
in the centre of the cornea, and at first its effects were more 
prominently visible throughout a wedge-shaped area, whose 
base was peripheral, its apex at the pomt irritated. To this 
area Dr. His applies the name of “ Reiz-bezirk,” or “ area of 
irritation.” The actual spot to which the irritant is applied 
may be termed the “ point of irritation.” 


«The cornea of a rabbit which has been subjected to intense traumatic 
irritation presents but little change to the unassisted eye halfan hour after- 
wards; but the microscope already reveals distinct histological changes. 
In the first place the superficial cells, especially those of the area of irritation, 
are obviously ene ies In contradistinction from their normal appearance, 
the body of the cell is well marked, and has remarkably granular contents. 
The nuclei are bright and sharply defined, without visible nucleoli, and are at 
once remarkable for their irregular and unusual forms. Having a general 
direction parallel with the cell, they are mostly more or less angular, instead 
of being round or oval; they are notched, or constricted, or horseshoe- 
shaped; they grow out on one side as though they would form buds, or 


HIS, ON THE CORNEA. ao 


they elongate and become dumb-bell or drumstick-shaped. Many of them 
are divided into two segments of altogether different form and size, and this 
change is found most frequently, on the one hand, in the immediate neigh- 
bourhood of the point of irritation, and on the other in the peripheral por- 
tion of the area of irritation. The superficial cells which lie external to 
the area of irritation, are far less affected than those just described; they 
are, indeed, as a general rule, more clearly visible than in the normal state, 
whence we may conclude to a widening of their cavity; but in other 
respects they exhibit no remarkable peculiarities. In like manner those 
corneal cells which are not close to the surface exhibit no perceptible 
change ; their bodies are not enlarged, and their nuclei are neither shrunken 
nor notched. 

“One hour after irritation the rabbit’s cornea exhibits an essential ad- 
vance. The dilatation of the cells, the peculiar alteration in shape, and 
partial division of the nuclei, has extended from the surface inwards; here 
also the cell-contents appear remarkably coarsely granular, and begin in a 
singular manner to retract from the cell-membrane. In fact, in the superficial 
layers, the contents have aggregated more closely around the nucleus, so as 
often completely to obscure the latter, and at the same time to leave a clear 
space between themselves and the dilated cell-membrane. The contents in 
this way form a kind of independent mass, everywhere separated from the 
cell-wall, and though repeating the form of the cell-cavity, surrounded by no 
membrane, but consisting of a mere granular conglomerate. In many of these 
masses of contents, the outlines of the nucleus are still distinguishable; but 
in others the nucleus is completely obscured, and in these cases one may 
easily be led to suppose that the contents and nucleus are the nucleus alone ; 
and this is the more easy, since after a time the nucleus in the interior, 
appears to swell and to become enlarged out of all proportion. ... . The 
withdrawal of the cell-contents from the wall is most remarkable at the 
edge of the cornea, or, in other words, in the peripheral part of the area of 
irritation ; here also the corneal cells are most enlarged, and in correspond- 
ence with the frequent divisions of the nuclei already observed in this 
region, we now meet in equal abundance with segmentation of the con- 
tent-masses agglomerated round the nuclei. These masses have in many of 
the cells broken up into two or more irregular portions of usually very 
unequal size. Under favorable circumstances a nucleus is discernible in 
each portion, and occasionally two are seen in the larger masses, so that it 
seems probable that the contents have divided in those cells only in which 
the nuclei have already multiplied. 

“The content-masses often send one or more branches inio the principal 
processes of the cells; and in the divided ones, these elongated portions 
have become separated from the rest. A process which commences, even at 
this early period, in some corneal cells, is the formation of endogenous cells. 
Among the peripheral cells with divided contents, in fact, there are some 
in which, instead of one or other of the separated masses of contents, a 
small rounded cell, with a cavity distinctly bounded by a membrane and a 
rounded, somewhat dark-contoured granular nucleus, is visible. This little 
cell, like the granular mass of contents itself, is not in immediate contact 
with the membrane of the corneal cell ; but is at first separated from it by 
a more or less broad clear space. It is frequently imbedded in a regular 
pit of the mass of contents, and so obviously fills the place of a separated 
segment of contents that it can hardly be doubtful it has arisen from such 
a segment, the granular mass surrounding the nucleus having differentiated 
itself into membrane and contents. 

“The cells about the ‘point of irritation’ (in these experiments, the centre 
of the cornea), exhibit a very different relative development, inasmuch as in 
them the process of division of the nucleus predominates, while the cells 


VOL. VI. F 


56 HIS, ON THE CORNEA. 


undergo no corresponding enlargement. This fact is worthy of particular 
attention, because, as we shall see, it lays the foundation for subsequent 
much more important differences. 

“The cells external to the area of irritation appear dilated in the superficial 
layers, but as yet without division of the nuclei and retraction of the 
contents ; in the cells of the deeper layers of the whole cornea hardly any 
change is perceptible.” —pp. 79—82. 


At two or three hours the alterations are of the same nature, 
though they have extended further both in the thickness and 
over the surface of, the cornea. At from sixteen to twenty 
hours the retraction of the cell-contents from the cell-wall 
has extended even to those corneal cells which lie close to the 
membrane of Descemet, and the same changes gradually 
take place in the deeper, as have already been described in 
the more superficial layers. Segmentation of the contents 
has but rarely taken place in the deep layers, but increases 
in frequency towards the surface throughout the whole 
cornea. 

“A complete series of stages of development is observable if we pass 
from the deep to the superficial layers. Solitary cells are seen with a single 
large granular content-mass ; in others, the contents have divided into two 
or more segments; among these are some which, together with the content- 
masses, contain one or two endogenous cells, and lastly, at the surface (in 
the peripheral part of the area of irritation), the corneal cells are changed 
into large and wide anastomosing sacs which are completely filled with a 
brood of endogenous cells, and in which no granular content-masses can any 
longer be seen. In some of these saccular corneal cells there are not more 
than two or three endogenous cells, but others contain twenty and more, 
and are many times larger than their normal size. The fundamental form 
of all the endogenous cells is round; but when aggregated in great numbers 
they frequently become polyhedral, by mutual flattening.”—p. 85. 


Dr. His remarks that in this stage the area of irritation, 
when examined with the naked eye, presents centrally and 
peripherally a turbid appearance, while the imtermediate 
portion is clearer. Now, in this intermediate space the cells 
exhibit hardly any endogenous cells, but only, as it were, 
the early changes leading to their formation. The central 
part, on the contrary, is as greatly altered as the peripheral, 
but from a different cause, namely, from the presence of 
innumerable nuclei, which have become developed by the 
subdivision of the nuclei of the corneal cells, and are now 
arranged in lines corresponding with the processes of the 
cells. The bodies of the cells, instead of bemg distended, as 
at the periphery, have commonly ceased to be distinguishable. 
Dr. His doubts whether these nuclei are surrounded by dis- 
tinct cell-walls. 

After sia days, the cornea is clouded throughout, and 
in the centre it appears yellowish and opaque, while parallel 
close-set vessels radiate from the margin over a zone of half 


H1S, ON THE CORNEA. on 


a line or a line in breadth. These vessels are developed by 
the anastomosis and coalescence with one another, and with 
the pre-existing vessels, of certain of the peripheral sacs con- 
taining cells whose origin is explained in the foregoing ex- 
tract: but for the details of these and the other changes 
which the corneal cells have undergone, we must refer to the 
original. Suffice it to say, that from first to last, every new 
histological element proceeds from the metamorphosis of 
those which pre-existed. Nothing but nutritive material is 
derived from without. 


“As the general result of the observations which have been detailed, we 
must place in the front rank the complete confirmation of the law already 
laid down by Virchow, ¢hat in inflammation of the cornea no free, indepen- 
dently distinguishable exudation exists. Neither is there an exudation into 
supposed interstices of the tissue, nor can any turbidity of the intercellular 
substance be observed, which can be regarded as the result of an exudation. 
All the changes which the cornea undergoes take place in the pre-existing 
elements of the tissue, and everyinflammatory opacity, softening, and desqua- 
mation that has hitherto been regarded as serous or fibrinous exudation ; every 
newly formed vessel and substance of a cicatrix, is the immediate product of 
altered corneal cells and their derivatives. It is only as a secondary result 
that the pre-existing intercellular substance undergoes changes, which are, 
as it were, imposed upon it by the changed energies of the cellular elements. 
Hence, in establishing a theory of corneal inflammation, our aim must be to 
study the laws of the changes of the cellular elements, their causes, and con- 
sequences, and to substitute determinate histological principles capable of 
scientific elaboration, in the place of the obscure notion of corneal exuda- 
tion.” —pp. 108-9. 


Reviewing his results with this object, Dr. His arrives at 
some singularly interesting conclusions. He conceives that 
three types may be distinguished among the modifications 
undergone by the corneal cells when subjected to inflamma- 
tory iritation—the first, in the cells about the neighbour- 
hood of the point of irritation; the second, in the superficial 
cells of the margin of the cornea; and the third, in the cells 
of all the deeper corneal layers. In all these cases the intro- 
ductory changes are the same; the cells increase in size; 
their nuclei divide, and their contents become retracted, and 
undergo segmentation; but in their further progress each 
type of cell differs from the other, not so much in the kind, 
as in the quantity and proportion, of the changes which it 
undergoes. In the deep layers the process is slow and im- 
perfect ; in the highly irritated central part, the cells increase 
but little im size, but their nuclei undergo rapid and frequent 
division ; in the periphery, on the contrary, the increase in 
size is great, and the subdivision of the nuclei falls far short of 
that observed in the central part. 


“In other words, the division of the nucleus is an activity of the cell, 
whereby the latter reacts when stimulated, quite independently of vascular 


58 HIS, ON THE CORNEA. 


influence ; while, on the other hand, the increase’ of the cell in size is in relation 
with the amount of matter supplied by the neighbouring vessels. 

“‘ We should express this at once as a law, that the vessels take no direct 
share in the origination of inflammatory histological changes, if observation 
did not furnish us with a fact in apparent contradiction therewith. If the 
influence of the irritant and that of the vessels could be regarded simply as 
two forces operating from two points on an intermediate space, with an 
intensity inversely proportional to the distance from their centres, then if the 
division of the nuclei were regarded as the effect of the stimulus—the in- 
crease of the cells as that of the vascular influence—the locality of the 
least nuclear division ought to coincide with that of the greatest cell- 
growth, and vice versé. Now observation shows that the latter is the ease, 
but not the former; for the point of least nuclear division falls, as we have 
seen, not at the margin of the cornea, but in the zone between it and the 
centre, the increase in the number of nuclei at the margin being from the 
very beginning by no means small. 

“Two possibilities offer themselves when we seek for an explanation of 
this fact; either the irritation proceeding from the centre undergoes a local 
intensification, in which case some nervous influence would suggest itself ; 
or we may assume that the peripheral cells, from the more favorable con- 
ditions of their existence, (the more ready supply of nutriment,) possess a 
greater irritability than the cells of the centre of the cornea, whence, with a 
slight irritation they react more intensely than the latter with a stronger 
irritation. 

“The last view appears to be the more unconstrained and natural—and 
we must especially completely renounce the idea of any direct influence of 
the nerves on the processes of nuclear division, since in the deep nerveless 
layers of the cornea the growth of the nuclei goes on in the same way as in 
the superficial ones, as soon as the irritant comes to act directly upon these 
more deeply seated parts.”—p. 113. 


Objections might be raised to the demonstrative force of 
the evidence on which Dr. His bases these conclusions. It is 
unfortunate that we do not know the effect of varying the posi- 
tion of the point of irritation, which would probably be very 
instructive. And it must be remarked that the direct in- 
fluence of a stimulant upon the life of the cell, or, in other 
words, in producing dilatation and nuclear division, is not 
proven; for one immediate effect of the stimulant is to alter 
through the nerves the state of the cireumcorneal vessels, and 
it is impossible to say, from Dr. His’s experiments, whether 
the earliest changes observed are the direct effect of the 
stimulant, or the indirect consequence of the modification 
produced by that stimulant on the supply of nutriment. 

Dr. His details certain observations upon the changes of 
texture exhibited by the cornea after section of the fifth nerve 
and in carcinoma melanodes ; and he concludes with some re- 
marks upon the histology of arcus senilis, whose true nature 
and connection with other forms of fatty degeneration were 
first shown by Mr. E. Canton. But into these matters we 
do not propose to enter, and we have only to add that Dr. 
His’s work is illustrated with numerous and excellent figures. 


59 


NOTES AND CORRESPONDENCE. 


A Fifty Pound Prize for Observations with the Microscope.— 
We beg to call the attention of our readers to the following 
advertisement : 


“MICROSCOPIC INVESTIGATION. 


“‘ Firry Sovererens will be given for the best Report on the Results of 
Microscopic Observation, applied to the Vegetable Physiology of Agricul- 
ture. 

“Tt is not thought desirable to confine the observer too strictly to any 
particular line of researches, the only necessary limit being, that the plants 
to be examined and reported upon shall be selected from those commonly 
cultivated ; such as the cereals, or those usually known under the names of 
pulse, root, or fodder crops. The structural formation of these plants—their 
ordinary vital processes—modifications of the above induced by climatic 
influences or the application of manure—morbid changes of their tissues 
consequent upon the attacks of insects or disease,— would all prove extensive 
and interesting fields of inquiry; and it must be left to the writers them- 
selves to select those particular branches of the subject on which they are 
able to supply the greatest amount of original iuvestigation.” 


This prize is offered by the Royal Agricultural Society of 
England, and the report is to be sent in during the month of 
March, 1858. The subject is a very interesting one, and 
some of our young vegetable physiologists could not enter 
upon a more interesting field of investigation. 


On the Stellate Bodies of Nympheacee.—The well-known 
stellate bodies met with in the intercellular spaces of the 


yi 


Satie 


a 


nN 
=} 


Ny BAe 
ps 


re 
2. 


Plan of vertical section of the leaf of Nuphar luteum. Mag. 75 diam. 


60 MEMORANDA. 


stems and petioles of the Nymphzacez, occur also as a 
noticeable feature in the leaves, as 1s well seen in a vertical 
section of the floating leaf of the common yellow water-lily. 
They are readily distinguished from the cells forming the 
parenchyma of the leaf, by their large size and tuberculated 
walls, as well as by the absence of chlorophyll in their 
interior. They lie in the compact upper layer of parenchyma, 
but as their finger-like processes pass mostly upwards and 


y : A 


a——S 
EEE =X SZE| 
EAA ja : = = ——<F Z ZZ 
©ME] ]AzZ= FB <—. 
LZ zg 


Perpendicular section 
Perpendicular section of upper layer of leaf through the leaf of Nuphar. 
of Nuphar. Mag. 300 diam. Mag. 300 diam. 


downwards, the latter project more or less into the air-spaces 
among the cells of the spongy tissue on the lower side of the 
leaf, while the superior processes reach quite to the upper 
epidermis, where, in these floating leaves, the stomata are 
situated, the lower surface, like that of submerged parts 
generally, having none. It is difficult to make out the rela- 
tion of the cell-processes to the stomata, as the latter are small 
and very indistinct in a vertical section, but, im some cases, at 
least, these pores seem to open just over the terminal points 
of the processes. In such cases, the stellate cells may serve 
the purpose of establishing an indirect communication be- 


MEMORANDA. ; 61 


tween the atmosphere and the air passages in the lower layer 
of parenchyma, through the denser tissue which lies over it, 
the more usual communication, by stomata opening immedi- 
ately into the cavaties of the spongy parenchyma, being pre- 
vented by the submersion of that side of the leaf on which it 
is situated.—Grorce Oattvisr, M.D., Lecturer on Institutes 
of Medicine and Histology, Marischal College and University, 
Aberdeen. 


62 


PROCEEDINGS OF SOCIETIES. 


Royaut Society, June 12th, 1856. 
Lord Wrottesley, President, in the chair. 


Letter from Dr. W. Brrp Herapatu to Professor Stokes, 
“ On the Detection of Strychnia by the formation of Iodo- 
strychnia.’ Communicated by Professor Stoxss, Sec. 
R.S. 

Bristol, June 7th, 1856. 

My prar Srr,—Will you do me the favour to announce 
to the Royal Society, that I have been engaged during some 
time past in the application of my discovery of the optical 
properties of iodo-strychnia to the detection of this alkaloid 
in medico-legal inquiries? I find it perfectly possible to 
recognize the 10,000th part of a grain of strychnia in pure 
solutions by this method, even when experimenting on very 
minute quantities. In one experiment I took z,55th of a 
grain only, and having produced ten crystals of nearly 
equal size, of course each one, possessing distinct and 
decided optical properties, could not represent more than the 
zodooth part of a grain; in fact, it really represents much 
less, Imasmuch as one portion of the strychnia is converted 
by substitution into a soluble hydriodate, and of course 
remains dissolved in the liquid. 

I had hoped to have been able to complete this matter 
during this summer, but I now find it impossible to do so in 
time for this session of the Royal Society. I trust to be 
able to do so before Christmas, however. Will you oblige 
me by getting this notice inserted in the ‘ Proceedings,’ as a 
new test for strychnia at this juncture possesses considerable 
interest, the colour-tests having been so dubiously spoken of 
recently by toxicologists ? 

In order to operate in this experiment, it is merely neces- 
sary to use diluted spirit of wine, about in the proportions of 
one part of spirit to three of water, as the solvent medium, 
and to employ the smallest possible quantity of the tincture 
of iodine as the reagent, and after applying heat for a short 
time, to set in repose. On spontaneous evaporation or cool- 
ing, the optical crystals deposit themselves, and may be 
recognised by the polarizing microscope, according to the 


PROCEEDINGS OF SOCIETIES. 63 


description given of this substance in a former notice to the 
Society in June last. 

You may remember that this proposition was also con- 
tained in my paper on iodo-strychnia, which was withdrawn 
from the Royal Society by me in June last, in consequence 
of a necessity for revision and the completion of experiments 
requisite to settle the formula of that peculiar substance, and 
the introduction of an abstract of the literature concerning it. 

I remain, &c., 
W. Brrpo HeErapatu. 


June 19th, 1856. 
Lord Wrottesley, President, in the chair. 


“ Researches into the nature of the Involuntary Muscular 
Fibre.’ By Gurorce Viner Ex.is, Esq., Professor of 
Anatomy in University College, London. Communicated 
by Dr. Suarpey, Sec. R.S. 


(Abstract.) 


Havine been unable to confirm the statements of Professor 
Kolliker respecting the cell-structure of the involuntary mus- 
cular fibre, the author was induced to undertake a series of 
researches into the nature of that tissue, by which he has 
been led to entertain views as to its structure in vertebrate 
animals, but more especially in man, which are at variance 
with those now generally received. The present communi- 
cation contains the results of these inquiries, which tend to 
show that the voluntary and involuntary muscles resemble 
each other very closely in the arrangement and constitution 
of their fibres. 

After adverting to the present state of opinion on the sub- 
ject, the author gives an account of his own observations, 
and treats successively of the interweaving of the fibres, their 
size, form, and ultimate structure; their mode of attach- 
ment at their extremities, their length, and the corpuscles 
connected with them. He devotes a section also to the 
question of the periodic formation and destruction of mus- 
cular fibres in the uterus, in its different conditions; and 
while he is led by his own investigations to recognise an en- 
largement in size of the individual fibres of that organ during 
pregnancy, followed by subsequent diminution, he is unable 
to confirm the doctrme of new formation. Moreover, he 
finds that durmg pregnancy a considerable amount of granu- 
lar matter, with round or oval granular-cells, is deposited 
among the fibres. He adduces reasons for believing that 


64 PROCEEDINGS OF SOCIETIES. 


this substance cannot be regarded as a blastema, nor its im- 
bedded cells as formative cells, for the production of new 
fibres ; and he is disposed to ascribe the enlargement of the 
uterus in pregnancy principally to the enlargement of the 
muscular fibres, and the addition of this new deposit. 

The following is a summary of the conclusions which the 
author has arrived at on the main subject of his inquiry :— 

In both kinds of muscles, voluntary and involuntary, there 
is an interweaving of the fibres with the formation of meshes. 

The fibres in both kinds are long, slender, rounded cords 
of uniform width, except at the ends, where they are fixed by 
tendinous tissue ; and in both, the size of the fibres in the 
same bundle varies greatly. 

In neither voluntary nor involuntary muscle is the fibre of 
the nature of a cell, but in both is composed of minute threads 
or fibrils. Its surface-appearance in both kinds of muscle 
allows of the supposition that in both it is constructed in a 
similar way, namely, of small particles or “ sarcous elements,” 
and that a difference in the arrangement of these elements 
gives a dotted appearance to the involuntary, and a transverse 
striation to the voluntary fibres. 

The length of the fibres varies in both cases with the organ 
or part examined, and the connection with tendon always 
takes place after the same manner, whether the fibre is 
dotted or striated. 

On the addition of acetic acid, fusiform or rod-shaped cor- 
puscles make their appearance in all muscular tissue; these 
bodies, which appear to belong to the sheath of the fibre, 
approach nearest in their characters to the corpuscles belong- 
ing to the yellow or elastic fibres which pervade various 
other tissues; and, from the apparent identity in nature of 
these corpuscles in the different textures in which they are 
found, and especially in voluntary as compared with mvolun- 
tary muscle, it is scarcely conceivable that m the latter case 
exclusively they should be the nuclei of oblong cells consti- 
tuting the proper muscular tissue. 

The paper concludes with a statement of the mode of pro- 
cedure which the author has found most suitable for examin- 
ing the tissue which forms the subject of his inquiry. 


Linnean Socruty, February 3d, 1857. 


On the Cultivation of Mosses. By the Rev. H. H. Hicerns. 
Communicated by N. B. Warp, Esq., F.L.S. 


| senp a few particulars respecting the cultivation of 


PROCEEDINGS OF SOCIETIES. 65 


Mosses, of which about two hundred and forty species have 
been planted in my bryarium, which is a glass case about 
4. feet 6 inches long, 22 inches from back to front, and 26 
inches in height. It is fitted with shelves, and has two doors, 
one of which is generally left only partially closed. The 
plants are in separate pots, and are never removed from the 
case, but are kept in the shade and frequently watered with 
a syringe. Care is taken to procure suitable kinds of soil ; 
but in most instances the soil is sparingly used, the pots being 
more than half filled with drainage. 

ANDREACEH.—A. rupestris flourished and fruited till the 
second season. If removed with a portion of the rock at- 
tached, it might last much longer. 

SpHaGNacez.—The pots were set in trays of water, and 
no soil was put into them. Six species, five of them in fruit, 
were planted, and did well for the first year. SS. acutiflorum 
alone fruited the second year. They are now almost extinct. 

Puascrea#.—From a fine patch of P. nitidum only one or 
two plants came up the second year. 

WetlssirE&.—Seem permanent. W. controversa fruits pro- 
fusely about a month before its usual time. 

Dicranrx.—Stylostegium cespititium from Ben Lawers 
soon perished. Dicranum polycarpum and D. virens from the 
same locality, flourish ; the former fruits vigorously. Eight 
other species, some of them Alpine, seem permanently esta- 
blished. Leucobryum glaucum does not alter in the least. 

CampyLorpopE&.—C. longipilus, from Scotland, thrives ; 
and the common species bears fruit. 

Porrizx.—P. Heimii dies rapidly. P. truncata fruits. 

TricHostomMEz.—T7ri. tophaceum and homomallum disap- 
pear. The Tortule mostly do well, but the case contains no 
Alpine species. 7. ruralis overgrows itself and dies. 

Encatyetex.—E. vulgaris fruited and disappeared. £. 
ciliata remains, but is barren. Two Alpine species from Ben 
Lawers are unhealthy. 

Hepwicirz.—H. ciliata remains, but wants attention. 

GRIMMIEH.—G. pulvinata is a charming little plant for 
cultivation, but must be kept rather dry. Several others do 
fairly. All the Racomitria, except two, flourish and are very 
ornamental. 

OrrHotricHe&.—Tied upon small blocks of wood, and 
suspended, they live, and some of them bear fruit, but do 
not appear thoroughly healthy. Zygodon Lapponicus and 
Z. Mougeotiu are on the wane. Tetraphis pellucida holds its 
own well, but does not fruit. 

PotyrRicHE®.—Pogonatum nanum is gone. P. aloides and 


66 PROCEEDINGS OF SOCIETIES. 


P. urnigerum grow, and fruit beautifully ; even P. alpinum 
does better than many. The Polytricha have not succeeded 
well. 

Bryex.—Aulacomnium palustre is most desirable for culti- 
vation; it grows freely, and the tall pseudopodia have been 
abundant and very interesting. Leptobryum pyriforme should 
be excluded if possible; it becomes a perfect pest, growing 
everywhere but in its own pot. Bryum: about twenty-four 
species of this genus grow in the case ; the best are B. nutans 
and carneum, both of them very beautiful in fruit. B. alpi- 
num retains its fine crimson colour. B.julaceum and B. Zerit 
both do well, whilst the common B. argenteum has been often 
changed, and is now given up. 8B. roseum has been disturbed 
a good deal, ¢ and 2 specimens having been planted together 
to try if fruit would be produced; but as yet there is no 
appearance of fertility. B. Marrati, B. calophyllum, and 
B. Warneum are not healthy. Mnium: all that have been 
tried do well. 

Merzrsirz.—Meesia uliginosa puts forth sete of prodigious 
length; a rather suspicious circumstance in respect of its 
congener M. longiseta. 

Funariex.—Physcomitrium pyriforme. The fruit in its 
season is so dense that not a leaf can be seen. 

BartramMie®.—Bartramia. All are included except B. 
rigida. The best and most satisfactory mosses for growing 
cultivation. Nothing of the kind can exceed them in beauty 
of colour, growth, and fruit. Catoscopium nigritum is gone. 

SPLACHNEX.—S. ampullaceum and S. sphericum have been 
only lately received ; but Tetraplodon mnioides, on the bones 
of a rabbit, has grown and fruited for two seasons most 
vigorously. 

Fiss1DENTE are gems for cultivation. F. adiantoides is a 
portion of a specimen which has been in cultivation for twenty 
years. <Antitrichia curtipendula is not healthy. 

IsornectE®.—The Pterogonia are weakly. The Jsothecia 
flourish. Climaceum dendroides has been very fine, but now 
droops. Leskea sericea and L. polycarpa are very beautiful. 
L. latebricola and pulvinata are fast disappearing. 

Hypnenz. Of Hypnum sixty species are included. They 
are not easily kept in order on account of their straggling 
habit. The vitality of the plant seems to leave the root and 
the centre, and to reside almost entirely in the extremities. 
If these be cut off, the plant will not throw up fresh shoots 
from the roots, but perishes. In some instances I have 
therefore cut off and planted in fresh and suitable soil the 
extremities of the fronds; and these have made young and 


PROCEEDINGS OF SOCIETIES. 67 


vigorous specimens. The experiment is however too recent 
to be considered conclusive. Many of the rare Alpine species 
have been tried, but most of them are in a sickly state. 
H. Crista-Castrensis seems to thrive but does not form so 
handsome a plant as H. uncinatum. H. loreum becomes in 
appearance exactly like H. squarrosum. H. atro-virens, from 
Ben Lawers, is very beautiful. No Hypna fruit with me but 
those which are commonly found fertile; H. cordifolium is 
perhaps an exception. 

Omatim.—O. trichomanoides is healthy. Neckera crispa is 
tied to a flat stone and suspended ; it is in a very satisfactory 
condition. 

Hooxerir#.—H. lucens never changes: in winter and 
summer it is alike beautiful. It is now fruiting pretty freely. 

Fontinatex.—F. antipyretica fails. 

Hepaticxz.—Riccia fluitans grows in a very interesting way. 
Targionia hypophylla is gone. The Marchantie grow too 
freely. Jungermannie: I have had twenty-seven species ; 
some of them, e. g., J. tomentella, J. ciliaris, J. spinulosa, and 
J. asplenoides are as beautiful as any plants in the case. 
Some of the species fruit profusely, pouring out a stream of 
silvery translucent fruit-stalks, tipped with little shining ebony 
heads, which, when expanded, show very remarkable hygro- 
metric properties. J. nemoralis is covered with little dark- 
coloured gemme. 

Bartramia Halleriana grew last autumn with a fringe of 
Hymenophyllum, with which it was collected near Loch Lo- 
mond, and was as round and as finely in fruit as a bush of 
mistletoe. 


Roya Institution or Great Britain, March 27th, 1857. 


The Duke of Northumberland, K.G., F.R.S, President, in 
the chair. 


On the Aquarium. By Rosert Warineton, Esq. 


Tue speaker opened the evening’s demonstration, by 
stating that he had immediately responded to the invitation 
of the managers of the Royal Institution to deliver this dis- 
course, on what they had been pleased to call his ‘‘ own sub- 
ject,” from the feeling, that as the originator of the aquarium, 
he was in duty bound to afford, to all those who had taken 
up this “‘ new pleasure,” every assistance, from the result of 
his own experience, that lay in his power, in order to render 
the undertaking more easy and pleasurable; and for this 


68 PROCKEDINGS OF SOCIETIES. 


purpose he proposed to lay before his audience, as far as was 
practicable, a demonstration of the principles on which it was 
founded, particularly as very erroneous ideas had been pro- 
mulgated on the subject, and instructions given in several 
most engaging publications, which might tend materially to 
mislead and disappoint those inclined to recreate themselves 
with this interesting subject. 

History.—After a short sketch of the several discoveries in 
the various branches of science embraced in this subject :-— 
as the experiments of Lower, Thurston, Hooke, and Mayow, 
on respiration and animal heat; the presence of air in water, 
and its necessity for supporting the life of fish, by the Hon. 
Robert Boyle; the discovery of fixed air, carbonic acid, by 
Dr. Black, and its production in respiration ; the experiments 
of Priestly, Ingenhousz, and Sennebier, on the action of sub- 
mersed aquatic vegetation exposed to light, in removing car- 
bonic acid, and restoring oxygen to the air dissolved in water, 
—all of which had been since substantiated by numerous 
experimenters. A cursoryreviewwas then given of the common 
employment of the ordinary fish-globe, the cisterns, tanks, 
pans, and tubs, with their fish and water plants, to be seen 
every day in our conservatories and green-houses, and the 
glass cylinders, used by almost every microscopist for pre- 
serving Chara, Nitella, Valisneria, and other lke plants in 
which the circulation of the sap was visible; as also for pro- 
pagating rotifers, stentors, and other microscopic animalcules ; 
the consideration of which points brought the subject up to 
modern times. Mr. Warington then proceeded to give an 
account of his own experiments, and the reasons which had 
led to their commencement, namely, the statements made for 
a series of years in our works on chemistry,* that growing 
vegetation would counterbalance the vital functions of fish. 
To test the truth of this, and its permanence,t a large twelve- 
gallon receiver was filled to about two thirds its capacity with 
river water, and some clean washed sand and gravel, with 
several large fragments of rockwork placed in it, the latter so 
arranged as to afford shelter to the fish from the sun’srays. A 
good healthy plant of Valisneria spiralis was then trans- 
planted, and as soon as it had recovered from this operation 
a pair of gold fish were introduced. The materials being 
thus arranged, all appeared to progress healthily for a short 
time, until circumstances occurred which indicated that 
another and material agent was required to perfect the adjust- 

* <Brande’s Elements of Chemistry,’ 1821, and repeated up to the 


present time. 
+ ‘Quarterly Journal of the Chemical Society,’ 1850, vol. iii, p. 52. 


PROCEEDINGS OF SOCIETIES. 69 


ment, and render it at all permanent, and which at the com- 
mencement of the experiment had not been foreseen. 'The 
circumstances alluded to arose from the natural decay of the 
leaves of the Valisneria, the increase of which rendered the 
water turbid, and caused a rapid growth of green confervoid 
mucus on the surface of the water, and upon the sides of the 
receiver; the fish also assumed a sickly appearance, and had 
this been allowed to progress they must have speedily perished. 
The removal of this decaying vegetation from the water as 
fast as it was formed became, therefore, a point of paramount 
importance, and to effect this, recourse was had to a very use- 
ful little scavenger,—whose highly important and beneficial 
functions throughout all nature have been too much over- 
looked, and its indispensable uses in the economy of animal 
life not well understood,—the water snail, whose natural food 
consists of decaying and confervoid: vegetation. Five or six 
of these little creatures, the Limnea stagnalis, were conse- 
quently introduced, and by their extraordinary voracity and 
continued and rapid locomotion, soon removed the cause of 
interference, and restored the whole to a healthy state. 

Thus then was established that wondrous and admirable 
balance between the animal and vegetable kingdoms, and by 
a lmk so mean and insignificant as almost to have escaped 
observation, in its most important functions. The principles 
which are here called into action are, that the water, holding 
atmospheric air in solution, is a healthy medium for the 
respiration of the fish, which thus converts the oxygen con- 
stituent into carbonic acid. The plant, by its vital functions, 
absorbs the carbonic acid, and appropriating and solidifying 
the carbon of the gaseous compound for the construction of 
its proper tissues, eliminates the oxygen ready again to sus- 
tain the health of the fish. While the slimy snail, finding 
its proper nutriment in the decomposing vegetation and con- 
fervoid mucus, by its voracity prevents their accumulation, 
and by its vital powers converts that which would otherwise 
act as a poisonous agent into a rich and fruitful pabulum for 
the vegetable growth. Reasoning from analogy, it was 
evident that the same balance should be capable of being 
permanently maintained in sea water, and thus a vast and 
unexplored field for investigation opened to the research of 
the naturalist ; and this proved on trial to be the case. 

Principles of the Aquarium: the Air contained dissolved in 
Water.—The ordinary atmospheric air is found to be com- 
posed of 79 volumes of nitrogen gas and 21 volumes of 
oxygen ; and water has the power of absorbing gaseous bodies 
in varying proportions, thus: 100 volumes of water, at a 


70° PROCEEDINGS OF SOCIETIES. 


temperature of 60° Fahr., and under ordinary barometric 
pressure, will absorb— 


1:56 volumes of nitrogen gas, 
3°70 AS oxygen gas, 
100:00 if carbonic acid gas ; 

and hence we find that the air absorbed by water, and existent 
in rivers to the extent of from 2 to 3 per cent., consists of 
about 29 of oxygen and 71 of nitrogen. In fresh-fallen rain 
and melted snow it ranges from 30 to 35 per cent. of oxygen, 
and in some spring waters it has reached as high as 88 per 
cent. This oxygen, by the process of respiration, is converted 
into carbonic acid gas, or mephitic air, the choke damp of the 
coal-pit, a gas highly poisonous to animal hfe; but here 
comes into play that beautiful and wonderful provision which, 
by the action of growing vegetation under the influence of 
the sun’s light, converts this baneful agent into vital oxygen, 
the ‘ breath of life.” 

Water, fresh and marine.—The water used for the aquarium 
should be clean, and taken direct from a river, or from a soft 
spring, and should not have been purified by means of lime. 

As regards sea water, it should, if possible, be taken at a 
distance from shore, and at the period of high water. If 
artificial sea water is employed, it should be made either 
from the saline matter obtained by the evaporation of sea 
water,* or by the following formula: 


Sulphate of Magnesia . . 71 07. 

ES inane)? ay See 
Chloride of Sodium . . . 484 ,, 

7 Magnesium. . 6 ,, 

2 Potassium’ a 
Bromide of Magnesium. . 21 grains. 
Carbonate of Lime . . . 21 


+) 


These quantities will make ten gallons. The specific gravity 
of sea water averages about 1-025 ; and when from evaporation 
it reaches above this, a little rain or distilled should be added, 
to restore it to the original density. 

Vegetation —The plants best fitted for fresh water are the 
Valisneria spiralis, the Myriophyllum, Ceratophyllum, and 
the Anacharis, all of them submersed plants, and fulfilling 
the purposes required most admirably. From the great sup- 
ply of food in the aquarium, the growth of the Valisneria is 
very rapid, and it requires, therefore, to be thinned by weed- 


* This is prepared by Messrs. Brew and Schweitzer, of 71, East Street, 
Brighton. 


~ 


PROCEEDINGS OF SOCIETIES. 71 


ing; this should never be done until late in the spring, and 
on no account in the autumn, as it leaves the tank with a 
weakened vegetation at the very time that its healthy func- 
tions are most required. 

The vegetation of the ocean is of a totally different cha- 
racter and composition, being very rich in nitrogenous con- 
stituents. There are three distinct coloured growths—the 
brown or olive, the green, and the red. For the purposes of 
the aquarium, where shallow water subjects are to be kept, 
the best variety is the green, as the Ulve, the Enteromorpha, 
Vaucheriz, Cladophora, &c. These should be in a healthy 
state, and attached to rock or shingle when introduced. We 
shall have occasion to notice the rhodosperms under the head 
of light. 

Scavengers —A most important element in establishing 
and maintaining the permanent balance between the animal 
and vegetable life; without which no healthy functions can 
be secured, and the aquarium must become a continued 
source of trouble, annoyance, and expense. The mollusc 
which was first employed, the Limnea stagnalis, was found to 
be so voracious, as it increased in size, that it had to be 
replaced by smaller varieties of Limnez, by Planorbis, and 
other species of fresh-water snail. The number of these should 
be adjusted to the quantity of work they are required to per- 
form. In the marme aquarium, the common periwinkle 
fulfils the required duties most efficiently, and is generally 
pretty active in his movements. The varieties of trochus are 
also most admirable scavengers ; but it must be borne in mind 
that they are accustomed to mild temperatures, and will not 
live long im a tank lable to much exposure to cold. The 
nassa reticulata not only feeds on the decaying matters ex- 
posed on the surface of the rockwork and shingle, but bur- 
rows below the sand and pebbles with the long proboscis 
erected in a vertical position, like the trunk of the elephant 
when crossing a river. But in the ocean there are innu- 
merable scavengers of a totally differmg class, as the anne- 
lids, chitons, starfish, nudibranch molluscs, &c.; thus afford- 
img a most beautiful provision for the removal of decaying 
animal matter, and converting it imto food for both fish 
and man. 

Light.—It is most probable that the greater amount of 
failures with the aquarium have arisen from the want of a 
proper adjustment of this most important agent; the ten- 
dency being generally to afford as much sun’s light as pos- 
sible ; but, on consideration, it will be found that this is an 
erroneous impression, When the rays of light strike the 

VOL. VI. G 


72 PROCEEDINGS OF SOCIETIES. 


glassy surface of the water, the greater part of them are 
reflected, and those which permeate are refracted and twisted 
in various directions by the currents of the water; and where 
the depth is considerable, it would be few rays which would 
penetrate to the bottom: but let the surface become ruffled 
by the passing wind, and it is little light that can be trans- 
mitted; and when this same disturbing cause lashes into 
waves and foam, not a ray can pass, and all below must be 
dark as night. Too much light should therefore be avoided ; 
and the direct action of the sun prevented by means of blinds, 
stipling, or the like. It is a great desideratum to preserve the 
growth of the lovely red alge in all their natural beauty, and 
prevent their becoming covered with a parasitic growth of 
green or brown coloured plants; this can be effected by 
modifying the light which illuminates the aquarium by the 
intervention of a blue medium, either of stained glass, of 
tinted varnish, coloured blinds, &c. The tint should be that 
of the deep sea, a blue free from pink, and having a tendency 
rather to a green hue. This modified light affects also the 
health of those creatures which are confined to shallow waters, 
so that a selection of the inhabitants must be made. 

Heat.—The proper control of this agent is also most 
material to the well-being of these tanks, for experience has 
proved that an increase or diminution of temperature beyond 
certain limits acts most fatally on many of the creatures 
usually kept. These limits appear to be from 45° to 75° 
Fahrenheit. The mean temperature of the ocean is estimated 
to be about 56°; and this does not vary more than 12° through- 
out the varying seasons of the year, showing the extreme 
limits to be from 44° to 68°. Great care should therefore be 
taken to afford as much protection as possible, by the arrange- 
ment of the rockwork, both from the sun’s rays by day, and 
the effects of radiation at night, as from the small volume of 
water contained in the aquarium these effects are rapidly 
produced. 

Food.—As many persons, to whom those interested in 
these matters have naturally looked for instruction, have 
decried the idea of feeding, it will be necessary to offer a few 
remarks on that point. How creatures so voracious as most 
of the denizens of the water are, both fresh and marine, are 
to thrive without food, is a question it would be difficult to 
solve; common sense would say they must gradually decrease 
in size, and ultimately die from starvation. The food em- 
ployed should be in accordance with the habits of the fish, 
xe. For the vegetable and mud feeders, vermicelli, crushed 
small, with now and then a little animal food, as worms, 


PROCEEDINGS OF SOCIETIES. 73 


small shreds of meat, rasped boiled liver, and the like. For 
the marine creatures, raw meat dried in the sun and moist- 
ened when used, answers very well. Oyster, mussel, cockle, 
raw fish, shrimps, and the like matters may be employed ; 
these should be cut or pulled into very small pieces, and 
never more given than they can at once appropriate ; and if 
rejected by one, it should be transferred to another, or re- 
moved from the tank. In the case of Actinia, they require, 
from their fixed position, that the food should be guided to 
their tentacles ; and if the animal food, of whatever kind, is 
soaked in a little water, and the water thus impregnated with 
animal fluids be dropped in moderate quantity into the tank, 
it will afford food for the small Entomostraca and smaller 
creatures with which the water abounds, and which constitute 
the food for many of them. 


A few observations were also made on the construction of 
a microscope for the purpose of employment in connection 
with the aquarium, and the method in which such an instru- 
ment could be used.—R. W. 


Dustin University ZooLocicaL AND BoTanicaL ASsocIATION, 
January 16th, 1857. 


R. Ball, LL.D., President, in the chair. 
Catalogue of Desmidiacee. By Wm. Arcuer, Esq. 


Tue following list of the Desmidiaceze which I have found 
about the “ Feather-bed”’ and “ Seechon” mountains, near 
Dublin, is not, of course assumed to be a complete list. It 
is, however, a perfect one (with, perhaps, the exception of the 
genus Pediastrum) of the species I have met with in my 
limited experience; and I have no doubt but subsequent 
search will very much extend it. I have ventured to append 
to each species an opinion as to its frequency or rarity, which, 
I need hardly state, is to be interpreted as the result of my 
own experience only in a limited district. Some of those I 
have marked as rare may ultimately prove frequent. I am 
inclined to corroborate an observation made in Mr. Ralfs’ 
beautiful ‘ Monograph,’ as to the non-occurrence of the same 
species in the same pools from year to year. For instance, 
in the year 1855, a certain pool produced Didymoprium Bor- 
reri in great abundance. During 1856 I could not find a 
single specimen of that species; but its place was taken by 
a considerably less abundant development of AHyalotheca 
mucosa. 


74. PROCEEDINGS OF SOCIETIES. 


The “ swarming” movement of the contents of the fronds 
of many species I have found to be very frequent. Mr. 
Ralfs suggests these moving granules may be analogous to 
the zoospores of other algee, and perform a similar function. 
The movement resembles somewhat that observable in the 
fovilla of pollen. If these granules be zoospores, and even 
a moderate proportion of the same should prove productive, 
should we not expect to find the Desmidiacez in greater 
myriads in the waters they frequent than they really are? I 
have noticed the movement equally active in both the old 
and newly formed segments, and while even yet undergoing 
the process of division. I regret I have only been suffi- 
ciently fortunate to meet with the true reproduction of the 
sporangia in these species. 

Perhaps it may not be out of place if I add, with regard to 
the collection of the Desmidiacez, that I have found the 
most expeditious method of gathering the smaller species 
(which adhere, forming a cloud-like mass round the leaves of 
plants or similar foreign objects) to be, to bring a small phial 
under the water, gently to push the blade of grass or sedge, 
or other such object, into it, snip it off, and thus retain the 
Desmids adhering, rather than to strip the plants with the 
hands, frequently rather a tedious and difficult process. The 
larger species I have found more abundant, not in the deeper 
pools, but rather in shallow water, an inch or two in depth, 
and in which there exists a very slight trickle of water per- 
manently throughout the summer. 

In regard to precise localities for the species mentioned in 
the list, I regret I cannot be more definite. Along the 
“ Piperstown Road to Glencree,” there are a number of 
pools, as well as on each side of the “ Military Road” over 
the “ Feather-bed Mountain,” and these, with the few excep- 
tions mentioned in the list, produced all the species which I 
have had the pleasure to meet with. Most ponds and streams 
produce some species, especially of the genera Closterium, 
Cosmarium, Scenedesmus, Ankistrodesmus, and others. 


LIST OF DESMIDIACEA FOUND IN THE NEIGHBOURHOOD OF 
DUBLIN. 


Hyalotheca dissiliens (Smith), abundant. 

‘4 mucosa (Mert), * 
Didymoprium Borreri (2a/fs), not uneommon. 
Desmidium Swartzii (4y.), rare. 

Spherozosma excavatum (Ral/s), rare. 
Miorasterias denticulata (Bred.), common. 
Fs rotata (Grev.), bs 
4 papillifera (Bred.), not uncommon. 
Americana 6 (Hhr.), rare. 


PROCEEDINGS OF SOCIETIES. 79 


Micrasterias oscitans (2a/f), rare. 


a crenata (Bred.), not wwcommon. 
5 truncata (Corda), 
Kuastrum verrucosum (H/r.), rare ; base of “Seechon” mouutain. 
5 crassum (Bred.), not uncommon. 
4 oblovgum (Grev.), common. 
A affine (Ra//s), not uncommon. 
3 ampullaceum ( ), rare. 


s didelta (Zurp.), Tete 

” ansatum (£.), 

A pectinatum (Bred. ys not rare. 

Sc rostratum (Ra/fs), rare. 

cf elegans a (Bred.), frequent. 

A, binale (Zurp.), not uncommon. 
sublobatum (Bred.), rare. 

Cosinarium cucumis (Corda), not common. 
3 pyramidatum (Bred.), 


: bioculatum (Bred.), © 

3 granatum (Greb.), rare. 

= Meneghinii (Bred.), not uncommon. 

- crenatum (Ra/fs), rare. 

ie tetraophthalmum (A‘wfz.), rare. 

3 botrytis (Bory), not uncommon. [I met with in the canal water 


a form, probably a variety of C. botrytis, which, like it, is 
rough with pearly granules, but differimg in having the deep 
constriction not forming a linear notch on each side in the 
front view; but wider at the outside, causing the angles at 
the base of the segments to be more rounded; the segments 
broadest at the hase, and gradually narrowing towards the 
abruptly truncate ends in a concave manner, thus somewhat 
pointing away from each other at the lower angles of each, 
while the angles at the ends are more acute and “defined than 
in C. botrytis. The end view is narrow elliptic. | 


Ae margaritiferum a and 6 (Turp.), frequent. 
S Brebissonii (Menegh.), not unfrequent. 

a celatum ( ), rare. 

i: eylindricum (Ra/fs), rare. 

a5 cucurbita (Bred.), B 


phaseolus (Bred.), 7 
Xanthidium armatum (Breb.), frequent. 


A aculeatum (Hhr.), not uncommon. 
c cristatum a and 6 (Bred.), rare. 
%y fasciculatum a (Hhr.), 


= octocorne a (Hhr.), frequent. [My opinion is that Xanthidium 
octocorne (var. a), so called, should more properly come under 
the genus Arthrodesmus, slightly extending the characters of 
the latter, so as to embrace the organism in question. 
Xanthidium appears a very natural genus; but 1. octocorne 
seems out of place in it. Its affinity to some forms of /r- 
throdesmus incus cannot but be apparent. I have met with 
both species mixed in abundance. | 
Arthrodesmus convergens (Z/r.), not uncommon. 
incus a and B (Breb.), not uncommon. 
Stantastrum dejectum, a, 8, and y (Bred.), frequent. 
3 cuspidatum (Bred.), not unfrequent. 
3 Dickiei (Ra/fs), rare. 
1 muticum (Breb.), not rare. 


76 PROCEEDINGS OF SOCIETIES. 


Staurastrum orbiculare (Hhr.), not common. 


ui tumidum (Bred.), rare [“‘ Seechon” mountain ]. 
.. margaritaceum (/.), rare. 

E punctulatum (Bred.), not uncommon. 
cs hirsutum (Z/r.), common. 

55 teliferum ( ), rare. 

¥ polymorphum (Sred.), not uncommon. 
Se tricorne (Bred.), common. 

A controversum (Sved.), not uncommon. 
hh paradoxum (Meyen), Bs 

f6 brachiatum ( ), rare. 

os alternans (Breb.), ,, 


a asperum 6 (Breé.), ,, 

[I have met with a form of Staurastrum bearing some 
resemblance to S. spinosuwm, or rather between that species 
and §. avicula. 'The spines at the angles are forked to the 
base, and not merely at the extremities, and the intermediate 
spines are smaller than S. spizosum. The form agrees much 
better with the figure of S. avicula, provided that species 
had intermediate spines, than with that of S. spizosum. It 
is not uncommon, according to my experience, in the district 
to which this list appertains. | 

Didymocladon furcigerus a (Bred.), rare. [Slow stream between Round- 

wood and Devil’s Glen. May be more common, however. | 

Tetmemorus Brebissonii (M/exegh.), common. 

5 granulatus (Breb.), very common, 

Penium margaritaceum (Z/7.) not uncommon. 

»  eylindrus (Zhr.), ” 
»  digitus (Zhr.), very common. 
»  Brebissonii (Menegh.) ,, 

»  Closterioides ( ), rare. 

Docidium nodulosum (Bred.), not uncommon. 

is truncatum (Bred.), 

2 clavatum (Kutz.), a 

Ehrenbergii ( ), common. 

» asperum (Bveb.), rare. [Should a master-hand ever propose the 
erection of a new genus for the reception of this species, or its 
removal from Docidium, the step would meet with my approval. 
To my mind it is zo¢ a Docidium: it entirely wants the charac- 
teristic constriction of that genus, and I have looked carefully, 
but in vain, as Mr. Ralfs did, for terminal moving globules. I 
have found occasionally three or more individuals adhering end 
to end, like a filamentous conferva, with extremely long cells. 
The specimens I have met with were rather more dilated at the 
ends than is represented in Ralfs’ figures. ] 

Closterium lunula (Mziller), common. [This is a favorable species for 
observing the circulation. It is not, however, like that phe- 
nomenon in other vegetable cells, the current being here of 
a very fitful and irregular character. It possibly bears some 
relation to the movement of the free granules at the ends of 


the frond. I have scarcely ever found any difficulty in de- 
tecting it. ] 


3? 


* lanceolatum (Aw¢z.), not common. 
3 acerosum (Schrank), not uncommon. 
i turgidum (Z.), ‘5 

Bs Leibleinii (Awéz.), common. 


” Diane (Hhr.), 


22 


PROCEEDINGS OF SOCIETIKS. Al 


Closterium didymotocum (Corda), not uncommon. 


59 striolatum (#.), very common, 
a attenuatum (#.), rare. 

se juncidum ( Neh ss 

. rostratum (Zhr), ,, 


Spirotenia condensata (Bredb.), common, 
Ankistrodesmus faleatus (Corda), very common. 
Pediastrum tetras (#/r.), not uncommon. 
- heptactis (Zhr.), mn 
= Boryanum (Zurp.), ,, [I have met (rarely) in two or three 
of the cells the contents receded from the walls, and massed 
together into a single, globular, green body in the centre, so 
as to leave the remainder of the otlierwise normally formed 
cell quite empty. This took place in the outside row of, and 
not in neighbouring, cells. This body is possibly a gonidium 
destined for the propagation of the organism. I have seen 
somewhat similar bodies in the cells of a species of Spirogyra, 
not the result of conjugation. | 


i ellipticum (Z/r.), common. 
Scenedesmus quadricauda (7wrp.), very common. 
fp obliquus (Zzrp.), not uncommon. 


5 obtusus (Meyer), 


39 


Britiso AssociaTION FOR THE ADVANCEMENT OF SCIENCE. 
Dublin Meeting. 


Saturday, August 29th, 1857. 
Section D.—ZOOLOGY anp BOTANY, tnctuptne PHYSIOLOGY. 


Dr. Reprern described a method of applying the com- 
pound microscope to the sides or top of aquaria less than 
two feet in height. The arrangement consists of a vertical 
stem, supported by a heavy foot. On the stem a short trans- 
verse tube slides vertically and rotates on the axis of the 
stem, as well as on an axis at right angles to the direction of 
the stem. This transverse tube carries a long sliding arm, 
made use of as a lever, with arms of very unequal length. 
The short arm of the lever terminates in the cup of a ball- 
and-socket jomt. A short stem attaches a tube to the ball, 
and this tube allows that which carries the objective and 
ocular to slide through it in coarse adjustment; whilst a 
fine adjustment is made by acting on the long arm of the 
lever. The body of the microscope may thus be placed 
either vertically or horizontally, and placed either over an 
aquarium or applied to its side with equal ease in the use of 
the two-inch, the one-inch, and the half-inch objectives. 
For the purpose of illumimation, Dr. Redfern employs a 
small mirror, which is let down into the fluid, and is capable 
of being moved in any direction by a simple arrangement of 
brass wires shown to the Section. 


78 PROCEEDINGS OF SOCIETIES. 


Further Report on the Vitality of the Spongiade. 
By Mr. BowErBank. 


Tue author stated, that in his former Report he had 
detailed a series of observations on the inhalation through 
the pores and the exhalation of water through the oscula of 
a marine sponge, Hymenacidon caruncula, and that he was 
enabled to determine with certainty the capability which 
that sponge possesses of opening and closing the oscula at its 
pleasure, but that he could not in that series of observations 
satisfactorily determine the nature and powers of the imbi- 
bing pores, as those organs can only be seen distinctly in ope- 
‘ation Im very young and transparent specimens; he there- 
fore commenced a series of observations on the action of 
the pores in young specimens of Spongilla fluviatilis on 
the 3d of October, 1856. He found that in a specimen 
about half an inch in diameter, which had attached itself to 
a watch-glass, there was at the summit of a large oval infla- 
tion, which varied its form remarkably within a very short 
time, a single osculum which opened or closed in accordance 
with the necessities of the animal, and from which when in 
full action a powerful stream of water was poured forth. 
The inhalation of the water by the porous system presented 
some remarkable peculiarities. When in a state of repose 
the dermal membrane appeared to be completely imperforate. 
but when about to commence vigorous inhalent action, a 
slight perforation appeared here and there over its surface, 
the orifices gradually creased in size until the full diameter 
of the pores were attained, and their margin then became 
thickened and rounded. And if a little indigo be infused in 
the water, it is seen to be absorbed with avidity, and the 
inhalent action continued for a considerable period, the inte- 
rior of the sponge becoming strongly coloured by the indigo. 
After a time the rapid inhalent process ceased, either 
abruptly or gradually, and a very languid action only re- 
mained, and nearly the whole of the pores were closed ; 
when this operation was about to take place, the rounded 
margin of the orifice lost its form and became thin and 
sharp, and the circumference gradually melted inwards until 
the orifice was entirely closed, and not the slightest indica- 
tion of the organ previously existing remained,—the opera- 
tion of closing occupying rather less than a minute. When 
once closed these orifices do not appear to be re-opened, but 
fresh pores are produced in accordance with the necessities 
of the animal. The colouring matter absorbed during the 
period of active inhalation was apparent in the sponge from 
twelve to eighteen hours, and during this period the stream 


PROCEEDINGS OF -SOCIETIES. 79 


from the osculum when partially expanded was extremely 
languid. The author concluded by observing, that the 
structure and habits of the fresh-water sponges were in 
perfect accordance with those of the marie species. 


On Flustrella hispida. By Dr. Reprern. 


Tue author pomted out numerous inaccuracies in the 
existing descriptions of Flustrella hispida, under the names 
of Flustra hispida and Flustra carnosa—veferring especially 
to the facts that no spimes are ever to be found on that side 
of the ‘aperture of the cell next its base; and that whilst in 
specimens gathered in Kincardineshire the spines are placed 
on the septa all round the cells, in those gathered in Dublin 
Bay the spines for the most part form a semicircle over the 
aperture, two or three only being found on the sides of the 
cell in rare instances. The Doctor then described the struc- 
ture of the polypide after its removal from the cell, and its 
development by germination, describing its various stages 
from day to day, as it grew from a mere projection on the 
wall of the original cell, up to a complete cell with its spines 
and fully protruded polypide. The various characters of the 
perfectly formed zoophyte, with its cells set with spines; the 
most prominent features of its anatomical structure, and the 
growth of the new being from day to day by germination, 
were illustrated by a series of coloured drawings made by 
the author with the camera lucida; and microscopical 
preparations exhibited to the Section showed the characters 
of the cell, and of the polypide after its removal. 


Monday, August 31st, 1857. 
PHYSIOLOGICAL Svun-section. 


On the Alternation of Generations and Parthenogenesis in 
Plants and Animals. By Dr. LanKestER. 


Arter alluding to the phenomena of “ Alternation,” as 
described by Steenstrup in the Entozoa, Meduse, and Sertu- 
larian polyps, and to the phenomena of Parthenogenesis, 
described by Owen and Von Siebold, the author concluded 
his paper as follows: “ If we turn now to the vegetable king- 
dom, we find perfectly analogous phenomena presenting 
themselves. In fact, the modifications of the reproductive 
function, which have recently excited so much surprise, in 
the animal kingdom, are the normal forms of the function 
among plants. In the roots and branches of a tree we have 
a gigantic ‘ nurse,’ and the buds are its progeny. Just as we 
find the same secondary products called ‘gemmez,’ in animals 


80 PROCEEDINGS OF SOCIETIES. 


either remaining adherent to their parent-stocks, as in the 
Sertularian and other Zoophytes, or floating off, as in Hydra 
and many others, so we find the buds of plants remaining 
attached to the tree, or becoming separated from it. Just 
too as we find a different form assumed by the secondary 
offspring of the ‘ nurse,’ as in the scolex-head of the cystic- 
worm, so we find in such cases as those presented by the 
‘bulbillus,’ the ‘bulb,’ and the ‘sporule, different forms 
assumed by parts having the same relations in the plant as 
in the animal. So likewise in the plant we find a greater 
change of the secondary offspring taking place, when sexes 
are developed and flowers are produced, and the hermaphro- 
dite flower with its stamens and pistils is the representative 
of the segments (proglottides) of the tape-worm, with its 
male and female apparatus in a common envelope. We may 
go yet further with our analogies in the vegetable kingdom. 
Here also we have numerous cases in which the germ-cell, 
the ovule, is produced, and develops within itself an embryo, 
quite independent of the influence of the sperm-cell—the 
pollen. The cases seem to me to have a strict analogy, and 
no more simple way could be found of mastering the details 
of the reproductive phenomena of animals than by studying 
those in plants.” 
The paper was illustrated by the followimg diagram : 


GENESIS. 


Growth—Reproduction— Generation. 


HoMocENEsis. HETEROGENESIS. 
(Reproductive force acting through (Reproductive force acting through 
similar cells.) dissimilar cells, sperm-cells and 
germ-cells.) 
It is represented in— It is represented in— 
A. Plants by Phytoids. A. Plants by 
1. Isophytoids. 1. Gynophytoids. 
Buds. Female flowers. 
Pistillidia, &e. 
2. Allophytoids. 2. Androphytoids. 
Bulbilli. Male flowers. 
Bulbs. Antheridia, &e. 
Sporules, &c. 3. Androgynophytoids. 
> Hermaphrodite flowers. 
B. Animals by Zooids. B. In Animals. 
J. Isozooids. 1. Gynozooids. 
Gems, or buds. Females. 
2. Allozooids. Fi) Oe 
* Nurses ” (Steenstrup). 2. A nay suit 
** Avamozooids”’ (Huxley). oy 
“Virgin Aphides”’? (Owen). 3. Androgynozooids. 
“ Agamic eggs” (Lubbock), Hermaphrodites. 


“Drone bees” (Siebold). 


PROCEEDINGS OF SOCIETIES. 81 


On certain Pathological Characters of the Blood-corpuscles. 
By Mr. J. B. Hennessy. 


He stated the results of his microscopical observations on, 
first, healthy blood, and on, secondly, inflamed blood. The 
result to which he directed particular attention was, that in 
infiamed blood the corpuscles were smaller and darker than 
in healthy blood. In corroboration of his views, he quoted 
the remarks of M. Donne, of Mr. Wharton Jones, Mr. 
Gulliver, and many others, upon this change of size. Mr. 
Hennessy founded a theory of inflammation through increase 
of temperature, the occurrence of the buffy coat and the 
other phenomena being satisfactorily explained. 


On the importance of introducing a New and Uniform Standard 
of Micrometric Measurement. By Professor Lyons. 


He alluded to the great difficulties experienced by observers 
in enumerating, rendering, and even remembering the various 
kinds of measures now in use in these countries and on the 
Continent, portions of the English, Irish, and French inch 
and line, and decimal parts of the French millimetre. The 
high figure in the denominator and the number of decimal 
plans were exceedingly cumbrous. He (Dr. Lyons) would 
propose that some definite micrometric integer should be 
assumed, being a determinate part of unity. He proposed 
that this measure should be denominated a microline. He 
did not mean definitely to bind himself to the adoption of 
any standard, but would propose provisionally that the one 
ten-thousandth part of the English inch should be assumed 
and denominated the standard microline pro tem. He would, 
however, have his hearers bear in mind the present tendency 
of scientific men towards a decimal system. For his own 
part he would prefer the French decimal scale. 


Observations on the Flow of the Lacteal Fluid in the Me- 
sentery of the Mouse. By Josrry Lister, Esq., F.R.C.S. 


Eng. and Edin., Assistant-Surgeon to the Royal Infirmary 
of Edinburgh. 


Tuer experiments of which a short account will be given in 
the present communication, were performed in the summer 
of 1853, but have not been hitherto published. The objects 
for which they were undertaken were, in the first place, to 
observe the character of the flow of the chyle through the 
lacteals, a thing which, as far as I know, had never been 
satisfactorily done; and in the second place, to throw some 
light if possible upon the debated question whether or not the 


82 PROCEEDINGS OF SOCIETIES. 


lacteals possess the power of absorbing solid matter in the 
form of granules visible to the human eye. 

In the experiments made for the former purpose, a mouse 
having been put under the influence of chloroform about two 
hours after partaking of a full meal of bread and milk, the 
abdominal cavity was laid open by a median longitudinal 
incision, and the animal having been placed on its side upon 
a plate of glass, a coil of intestine was drawn out gently, 
sufficiently far to admit of the microscope being applied to 
the mesentery, which was kept moistened with water of about 
100° F. Under a ;4,-inch object-glass the lacteals were readily 
recognised as beautiful transparent beaded cords; the beads 
corresponding to the situations of the valves which were 
observed to be standing open while the chyle-corpuscles moved 
along through the tubes with a perfectly equable flow, at a 
rate of about a quarter of that at which the blood passes 
through the capillaries. There was nothing like rhythmical 
contraction to be observed in the vessels, and it was evident 
that the source of the movement of the fluid was some cause 
in constant and steady operation. Chyle-corpuscles, appa- 
rently fully formed, to judge from their size, were observed 
constantly passing along, even in parts very near to the intes- 
tine, the scene of absorption showing the rapidity with which 
those corpuscles are elaborated. These observations were 
repeated several times. 

The other set of experiments were conducted in the same 
manner, except that some insoluble coloured granular mate- 
rial, such as indigo, carmine, or flower of sulphur, was mixed 
with the bread and milk. The animals partook freely of the 
mixture, which also passed on into the intestines, yet none of 
the colouring particles were ever to be seen in the lacteals by 
aid of the microscope, although had they been present in the 
granular form in the chyle they would have been certainly 
detected, being quite different in appearance from the normal 
constituents of the fluid. It may be imagined that the colour- 
ing substances exercised a poisoning influence and paralysed 
the function of absorption. There was, however, no appear- 
ance of any such thing, the chyle presenting the same cha- 
racters both as to its constitution and rate of flow, as when 
simple bread and milk had been alone administered. 

These facts, though not perhaps absolutely conclusive, 
appear to throw great doubt upon the interpretation which 
has been given of alleged cases of absorption of indigo and 
some other granular substances, and render it probable that 
the lacteals are incapable of admitting visible solid particles 
through their parictes. 


ORIGINAL COMMUNICATIONS. 


Investication of a Stmete Rute for Finpine the Numer of 
Entrre Hexaconat Facets contained in a Given Crrcre. 


By H. M. 
I. Tue area of a hexagonal facet (the diameter bisecting 


3 
the sides bemg = 6) = ss 6? = & X *866025. 


II. The area of a circle whose diameter = N6d is N26? 
x 7854. 
Ilt. Then the number of areas in the circle, each equal 


N28? x -7854 eee 
to that of a facet, 1s  §2 x 866025 == IN? x 90691 = N?2 x 9 


oe 2 : 
or 7 oN nearly 


——— 


——<——— 
2 EX 
= \ 


VOL, VI. H 


84 ON HEXAGONAL FACETS 1N A CIRCLE. 


IV. But this does not represent the number of entire facets 
in the circle, for many of these facets will be cut through by 
the circle, and the fractional parts must be rejected (by the 
question). We must therefore seek a more accurate method 
of calculation. 


V. Take now, as Casr I, that of N an odd number, the 
centre of the circle containing the facets, comciding with the 
centre of one of the facets. 

It is evident from fig. 1 that hexagonal facets must be 
arranged on any surface, plane or curved, in the following 
order : 


Ist. A facet in the centre. 

2d. Six facets round this central one. 

3d. Twelve round those. 

Ath. Eighteen round the last ; and so on, increasing by six 
in each term of the series. 


Hence the whole number of facets in the hexagonal ar- 
rangement, whose diameter N = 2n + 1, may be thus found. 


Let H be the number required, then H, = 3x.» +1+1. 


EXAMPLE. 
N = 35 
2n = 34 

n=17 


~. H,=51 x 18+1=919. 


Case II. 


VI. If N be even, the centre of a circumscribing circle 
will fall in the bisection (A) of a side of a facet (fig. 2). 

Here, therefore, we must find, by the rule for Case I, the 
number of the facets in the half hexagon whose centre is the 
centre of the facet next to A (observing that if n be the 
number of facets in AB, n—1 will be the number of terms 
in the arithmetical series), twice the number so found will be 
the number in the whole hexagonal arrangement, less by the 
row of facets on the diameter AC(= 2n). 


“. Hy, =3n.n—1+2n +1. 


It has now been shown how to find the exact number of 


ON HEXAGONAL FACETS IN A CIRCLE. 85 


hexagonal facets in a given hexagonal arrangement of the 
same. 

This is a necessary step towards finding the number of 
such facets contained in a circle described about this hexago- 
nal group. 


VII. We know indeed that the number required must be 
(by § II) less than N? x ‘9 (=C) and not less than H, or H, 
(or H). 

The question therefore is,—Can we find a proportion of the 


difference C — H, which being subtracted from C, would give 
a remainder equal to the number required ? 

Now proportion, in the case of N = 164, is found, viz., by 
actually calculating all the ordimates in the segment of the 
circle beyond each side of the hexagonal figure, erected, on 
the versed sine, at intervals equal to the diameter of a facet, 
and then finding the number of facets that may be arranged 
between each pair of ordinates in succession to be so nearly 


L C — H) that we may well be contented with this approzi- 
4 y p 


mate rule for finding the number (8) of entire hexagonal facets 


contained in the given circle, viz., 
1 9 1y9 7 

=C — -(C—H) = — N?—-4 —N?— Her. 

ah (Cc H) rie era J 


86 ON HEXAGONAL FACETS IN A CIRCLE. 


ExaMPLe 1. 
N = 164 
9 
—N?= 24206 
10 : 
H = 20091 
9 
C=—N?—H = 4115 
io 1 


(c-H) (aN De are 


1 
.-S=C a (C — H) =24206 — 1028 = 23178. 


S as found by § (VII) = 23228. 
Error == 50. 
EXAMPLE 2. 
N=" 10 
C= /90 
ise 
4|19 
il 
2 Ek 
{(¢—) 


S=H+4=75. 
Which number will be found correct by mspection of fig. 2. 


EXAMPLE 3. 
ee Oe eos 
n = 34 
38n = 102 


H =8n.n+1+1= 8571 
1 
C—H = 4284 — 8571 = 718... 7(C — H) = 178 


gy “(C — H) = 4284 — 178 = 4106 =S. 


87 


On Ruasponema, and a New ALuiep GrENvs. 
By G. A. Warxer-Arnort, LL.D. 


Tue late Professor Smith was justly entitled to be placed 
at the head of those whose attention was directed to the 
Diatomacez. Possessed of excellent instruments, and of a 
mind clear and discriminating as to what the limits of a 
genus or species were, he was alone qualified, if he had ob- 
tained access to authentic perfect specimens, to correct the 
unavoidable errors of Kutzing, or extract what is valuable 
from the chaotic writings of Ehrenberg; the latter of whom, 
by his figures of numerous forms of which he had only seen 
very imperfect specimens, unaccompanied by precise, suffi- 
cient diagnostical characters, has done more to cumber the 
science with a load of useless names than can be rectified 
for many years to come. 

So long as Smith survived, I preferred committing my 
notes to him to dispose of as he thought proper, his senti- 
ments being in accordance with my own,—that it is better 
not to publish a new species, or give it a name, than to do 
so from scanty or imperfect materials which leave both genus 
and species doubtful. Even now I have some hesitation in 
writing on the subject, as my views are diametrically opposed 
to those who consider it necessary to give names to forms 
which, to the eye, appear distinct, but which have not struc- 
tural differences sufficient for a specific character; and this 
alone entitles them to be acknowledged or referred to by 
others. 

In the following I shall endeavour to make the characters 
as clear as possible. 

Smith has first correctly defined and explained the struc- 
ture of Rhabdonema. Each frustule of this genus has two 
valves or ends, which are alike, and marked with moniliform 
strie; these valves are separated by several annuli, which 
are cellulate; the annuli project into the interior septa, 
which are open in the middle. These septa are sometimes 
projected from the whole imner surface of the annulus; 
sometimes from one half only, and consequently do not then 
pass beyond the central aperture: the first are called oppo- 
site, the last alternate, septa; in either case, each septum is 
supposed to terminate at the middle; they may be entire, or 
with openings when they are said to be perforate. 

As many merely consult figures, it is necessary that I 
request my readers to keep the above in recollection ; or, if they 
possess Smith’s second volume of the ‘ Synopsis of British 


88 WALKER-ARNOTT, ON RHABDONEMA. 


Diatomacez,’ to peruse what he says, otherwise my present 
observations may not be understood. It will be also neces- 
sary to bear in mind that, in some other genera, as Achnanthes, 
where there is a dissimilarity between the two valves of the 
frustule, the one next the point of attachment is termed the 
inferior valve, the other the superior. These terms I shall 
have occasion to employ. 

Having received lately from Professor Harvey, of Dublin, 
some Algze of the group called Corallinacee, from New 
Zealand, I washed these thoroughly, in case of any diatoms 
being mixed with the sand and mud that accumulate about 
such, and obtained a few only; but two interesting and 
closely allied forms presented themselves, along with several 
of Kutzing’s species of Grammatophora, &c. Both had a 
resemblance to what I have found m the coarse or sandy 
portions of Ichaboe guano (imported about two years ago), 
and of which I distributed some slides under the fanciful 
but only provisional name of Gephyria, as I had not then 
sufficient materials to clear up its affinities. Of the two 
from New Zealand, one exhibited a side view which some- 
what resembled a species of Swrirella ; the second was elliptic- 
linear (as if one had compressed a ring), and apparently 
pierced with numerous pentagonal holes in a double row. 
These markings sometimes extended to the end of the valve, 
sometimes stopped half way from the middle. There were 
also two forms of front views, which it was difficult to con- 
nect with the side view peculiar to it. 

On afterwards examining the Corallines, I detected a small 
specimen of Ballia callitricha, and creeping on Corallina offici- 
nalis a little piece of Polyzonia Harveyana; on both of these 
I observed a diatom which resembled closely the genus Rhab- 
donema, but of which the thread was composed of not more 
than three frustules ; this, however, might have arisen from the 
remainder being broken off, although my present impression 
is that such an appearance was not accidental. From the 
scantiness of the materials I succeeded in obtaiming only a 
very small preparation of each; and although I kept them 
separate, still, in consequence of the previous washing along 
with the Corallines, a few frustules in both instances had 
been deposited on, or caught by the Alga, on which the 
other was parasitical. At first, then, I had some doubts if 
these two were distinct, as, in both, the valves were furnished 
with coste; but the front views exhibited a different ap- 
pearance, from the septa in the one being rudimentary, 
while in the other those nearest the valves were marked 
similarly to these, and scarcely distinguishable from them. 


WALKER-ARNOTT, ON RHABDONEMA. 89 


Doubts may arise whether what I have described as costz 
on the valve, are not strongly developed septa projected by 
the adjacent annulus and seen through the valve; and this 
hypothesis would increase the affinity of the first and third 
species to the second one. But a careful examination of the 
first species to be described, where observations can be more 
easily made than on the other two, leads to a contrary 
opinion: Ist, the striz are never seen on the valve except 
between the costz; on the lower valve they terminate where 
the costz terminate: 2d, I have not been able to detach a 
single valve so as to exhibit striz without the cost, or septa 
without striez. The two formations are thus dependent on 
each other, and the one is indissolubly united to the other; 
whereas in Rhabdonema and Grammatophora the septa can 
be separated, leaving the striated valve by itself. 

In all the three species the valve varies considerably in 
form; so that had I not obtained them in a tolerably 
separate state, I should have been puzzled whether to 
combine all imto one, or to constitute of them many more 
species than I have proposed. Indeed, when species of the 
same genus are much mixed and only known from deposits 
or dredgings, it is quite impossible to draw any satisfactory 
conclusions. 

Perhaps it might have been sufficient to unite the species 
I have to notice to Rhabdonema ; but the valves are not only 
furnished with costz, but these costz are differently ar- 
ranged on the two valves; whereas in all true species of 
Rhabdonema, the two valves are precisely similar to each 
other, and without coste. If the two genera be combined, 
the character must be enlarged, and then it will be no easy 
matter to exclude by it other genera which all agree are dis- 
tinct. I have therefore thought it preferable to separate the 
new one under the name of 


EUPLEURIA. 


Filaments compressed or arcuate, continuous, attached. 
Frustules annulate, indefinite; annuli plane, cellulete or striate 
on their circumference; septa opposite or alternate, rudi- 
mentary or perforate. Valves ovate, elliptical, or arcuate, 
with one median and several lateral costs; inferior with the 
coste and striz disappearing below the extremities of the 
valve, superior with them reaching to the extremity: striz 
moniliform, oblique. 

1. Eu. pulchella ; annuli as broad as the flat valves, cellu- 
late ; septa all rudimentary. 

Hab. New Zealand, on Polyzonia Harveyana. 


90 WALKER-ARNOTT, ON RHABDONEMA. 


Annuli numerous, about 11 in ‘001, with about 15 cells in 
‘001. Septa apparently wanting, but from the external ap- 
pearance of the frustule, they seem to exist, although in a 
very rudimentary state, and to be alternate; they have con- 
sequently no perforations. Valves the breadth of the annuli, 
flat, usually more or less ovate and acuminate, sometimes 
linear-oblong. Strize only between the costz, oblique, about 
30 in ‘001, easily seen with a quarter-inch object-glass. 

2. Eu. ocellata; annuli as broad as the nearly flat valves, 
finely striate ; the septa contiguous to the valves, perforate. 

Hab. New Zealand, on Ballia callitricha. 

Annuli numerous, about 13 in ‘001, with about 40 striz 
in ‘001. Septa opposite, those nearest the valves composed of 
coste similar to what are seen on the valves, but with the 
interstices open ; the rays on the front view (formed by the 
subjacent septa) diverging from the lower valve, and con- 
verging from the upper one, indicate that these openings 
enlarge, while the septa themselves become narrower and 
fainter as they approach the middle of the frustule, where 
they are evanescent or rudimentary. All the annuli do not 
project the septa simultaneously ; those next the valves do so 
first, the last projected being the most remote: a frustule, 
therefore, may present itself which has only the annulus 
next the valve provided with septa, and one solitary example 
occurred where even then they had not been formed or were 
wanting; when this takes place, the species can scarcely be 
distinguished from the followmg one, except by the flatness 
of the valve, the coarser striz on the annuli, and the breadth 
of the annuli as compared with the valve. Valves nearly flat, 
not perceptibly broader than the annuli, elliptic linear or 
sometimes slightly lunate, rounded at each extremity. The 
striz are so faint that I have not been able to observe 
them satisfactorily. 

Mixed with this, and parasitical along with it, are seve- 
ral frustules of what at first sight resembles a minute 
Himantidium ; but 1 have not yet ascertained its side view, 
and as its genus is as yet doubtful, it is unnecessary to allude 
to it further. 

3. Eu. incurvata ; annuli conspicuously narrower than the 
very convex valves, delicately striate ; septa entire. 

Hab. West coast of Africa (among guano from Ichaboe, 
1855).* 


* T would not have introduced this species had I not seen many front as 
well as side views of it, as it is seldom that any certain conclusion can be 
obtained from deposits, dredgings, or guanoes. As an instance of a mis- 
take occurring in that way, I may allude to Pleurosigma compactum, Grev., 


WALKER-ARNOTT, ON RHABDONEMA. 91 


Annuli few, about 5 in ‘001, with about 50 striz in ‘001. 
Septa apparently opposite and rudimentary, or if present are 
not marked by coste or perforations. Valves very convex, 
arcuate, or somewhat linear and lunate, considerably broader 
than the annuli, the entire frustule presenting the appear- 
ance of a little bridge (Gephyria) with a low parapet on each 
side. Striz oblique, only between the costz, very much 
fainter than in Hu. pulchella, but not seemingly much more 
numerous (from 36 to 40 in :001), although requiring careful 
illumination and an object-glass of high power (3-inch) to 
exhibit them. 

In all these the median line or costa is not quite straight, but 
shghtly bent in a zigzag manner, the lateral ones being gene- 
rally alternate and proceeding from the angles of the median 
one. In the inferior valve the median line projects slightly 
beyond the lateral ones, and there usually forms a little 
knob. 

I have not attempted to measure the distances of the strize 
or annuli with accuracy; the numbers I have assigned are 
therefore more to be considered as relative, and probably are 
very different from what others may determine them to be. 


I shall now give the generic character of Rhabdonema 
slightly restricted from what is given by Smith, with abridged 
characters of all the known species. 


RuABpONEMA, Kutz. 


Filaments compressed, continuous, attached, or stipitate. 
Frustules annulate, indefinite ; annuli plane, cellulate on their 
circumference ; septa opposite or alternate. Valves similar, 


which is a genuine species of Amphiprora. This was first found copiously 
in the living state, and properly understood by Mr. Ralfs, of Penzance; and 
as the specific name given by Dr. Greville is quite inapplicable to an AmpAi- 
prora, \ have no hesitation in changing it to 4. Ralfsic. 

A. Ralfsii; F. V. narrow, elliptical, deeply constricted; V. twisted 
equally from end to end; striz about 53 in ‘001.—A. didyma, Sm. Brit. 
Diat., t. 15, f. 125? (excl. the name and char.)—Plewr. compactum, Grev., 
M. J. V., t. 3, f. 9 (mame and char. erroneous). 

Hab. Penzance; J. Ralfs. Cumbrae; R. Hennedy. Dredged also in 
various places in the Clyde by Mr. Hennedy and Rev. Mr. Miles. 

The figure given by Sinith is equally characteristic of this species, and 
of what Dr. Gregory calls 4. Lepidoptera; but if the number of strie, 72 
in 001, be not an error of the press for 52, it can be neither. Dr. Gre- 
ville describes the strize as “ obscure,” which they are under a bad object- 
glass; but they are as conspicuous and as few in ‘001 as in Pleur. istuarit, 
which usually in this country accompanies it, both in the normal and dis- 
torted shells; the latter of which has both ends bent in the same direction, 
a structure that occurs in some other species of that genius, 


92 WALKER-ARNOTT, ON RIABDONEMA. 


elliptical, ecostate, with a median line, striate. Stric trans- 
verse, moniliform. 


Sect. I. Septa entire. 


1. Rh. arcuatum, Kutz. ; septa opposite; striz not reaching 
to the end of the valves. 

Hab. Shores of Europe, Africa, and North America. 

To this belongs Tessel/a catena of Ehrenberg. 

2. Rh. minutum, Kutz.; septa alternate; strize reaching to 
the extremities of the valves. 

Hab. Shores of Europe and North America. 

To this belongs Tessella catena of Ralfs. 


Secr. II. Septa alternate, with perforations along the middle 
between the margin and central aperture. 


3. Rh. Adriaticum, Kutz.; septa with one oval perforation. 

Hab. Shores of Europe, North America, Asia Minor, 
Mauritius, and Ceylon. 

Probably more diffused than any other species. To it 
belongs Tessella catena of Bailey. 

4. Rh. mirificum, W. Sm.; septa with several (3 to 12) 
irregular perforations. 

Hab. Shores of Ceylon and Mauritius. 

In this species the openings in the septa are irregular in 
form, and reach from the upper to the lower margin of the 
annulus ; while the portions of the septa that separate these 
are narrow, and resemble bars which are either straight 
across or slightly oblique. When two such septa cohere, the 
perforations seem to extend from the one end to the other, 
and are then in no instance, as far as I have seen, fewer than 
seven, including the central opening, but usually are much 
more numerous (20 to 25). 


In my preliminary remarks I have alluded to Achnanthes. 
I may here take this opportunity of stating that A. brevipes 
of Kutzing, which has a rather short stipes and valves with 
acute extremities, has been found lately (November, 1857), 
by Mr. Okeden, at Neyland, in South Wales. This is re- 
ferred by Smith to A. longipes, on account of the presence of 
costz on the valves, along with moniliform striz: to this 
there is no valid objection; but, in that case, it ought to be 
noticed as a well-marked variety, and the word “ obtuse,” in 
reference to the valves, deleted from the specific character, 
as by no means applicable to this form of the species. Mr. 
Okeden has also found (March, 1857) at Neyland the A. 
parvula of Kutzing! a species which must be removed from 


BRIGHTWELL, ON RHIZOSOLENIA. 93 


the section in which Kutzing has placed it (from using an 
inferior microscope), as the striz are very conspicuous with a 
good lens, being as few as 33 or 34 in ‘001. It differs from 
the true A. brevipes of Agardh, by the elliptic-oblong obtuse 
valves ; from A. subsessilis by the usually numerous frustules 
and the distinct and somewhat elongated stipes; and from 
both by the much finer striz. 


Remarks on the Genus “ RuizosoLventa” of EHRENBERG. 
By Tuomas Bricutwe.t, Esq., F.L.S., Norwich. 


Amone the remarkable forms lately detected in Ascidie 
and Noctiluce, specimens have been found of some which 
appear to belong to the genus Rhizosolenia, of Ehrenberg. 

Having had, in this case, as in that of Chetoceros, an op- 
portunity of examining the species in a tolerably perfect 
state, we hope to be able to exhibit the true character of 
several more of those fragmentary and unsatisfactory forms 
which Ehrenberg, mm his various works, and particularly his 
‘ Microgeologie,’ has, as we conceive, too hastily and inju- 
riously to science, erected into genera and species. 

The characters given by him of the genus Rhizosolenia 
are “lorica tubular, with one extremity rounded and closed, 
while the other is attenuate and multifid, as if termimatimg 
in little roots.” He describes five species, some of which 
do not at all agree with the above characters; and the late 
Professor Bailey added a sixth under the name of R. hebe- 
tata. The greater part of these supposed species are, as we 
believe, only fragments of the silicious organisms we are 
about to describe, or of kindred species, and to enable the 
reader to judge of the correctness of our views, we have 
given copies of several of Ehrenberg’s published figures, as 
well as figures of all our newly-discovered perfect forms. 

Ehrenberg’s five species are* 

1. Rh. Americana, from Virginian earth. Of this he 
gives no less than eleven figures, most of them certainly not 
belonging to this genus. 


* These species (and a sixth clearly not belonging to it) are described in 
Kutzing’s ‘Species Algarum,’ p. 24, where the references to Ehrenberg’s 
works or papers, in which they first appeared, are to be found. 


D4: BRIGHTWELL, ON RHIZOSOLENIA. 


2. Rh. pileolus. A doubtful species. 

3. Rh. campana, Bermuda. No figure is given of this; but 
from the description it appears to be a terminal section of a 
Rhizosolenia. 

4, Rh. calyptra, South Sea. This is clearly the calyptri- 
form terminal process of a Rhizosolenia, very like our Rh. 
styliformis. 

5. Rh. ornithoglossa. The terminal process of the same 
species. Of Bailey’s Rh. hebetata we were favoured with 
specimens by the late lamented professor. It is clearly dis- 
tinct from any of the above, and from any of our species. — 

We present the following as a synopsis of the species 
which have come under our observation. 


RHIZOSOLENIA. 


Filamentous, frustules subcylindrical, greatly elongated, 
silicious, marked by transverse lines, extremities calyptri- 
form, pointed with a bristle. 


Species. 


1. Rh. styhiformis——Frustules from six to twenty times 
longer than broad ; transverse lines obvious ; terminal process 
at the base spathulate and bifid; straw colour to chestnut 
brown. 

“Found in the stomach of an Ascidia taken from oyster 
shells, dredged twenty or thirty miles from the Yorkshire 
coast, at a place a little to the north of the Humber, known 
as the ‘Silver Pit?” (Mr. Norman, of Hull, in ‘ Annals 
Nat. Hist.,’? vol. xx, p. 158). In Noctiluce, Gorleston, 
Suffolk. (Col. Baddeley.) In guano, Callao, often in 
little bundles of fragments. In Salpe. (Dr. Wallick). 

The base of the calyptriform process is carried out into a 
spatula-formed elongation, bifid at the end; the lines of the 
bifid division run upward on either side, with a stout nerve, 
to nearly the apex of the cone. Boiled in acid, the frustules 
break up, and the calyptriform processes in an isolated but 
perfect state, and detached imperfect rings are only to be 
found. (Pl. V, fig. 5.) 

2. Rh. imbricata.—Frustules four to seven times longer 
than broad, punctated; terminal process subulate, entire; 
pale straw colour. 

In Ascidiz with the former. (Mr. Norman.) In Nocti- 
lucee. (Col. Baddeley.) 

The direction of the transverse lines and puncta give this 
species an imbricated appearance. (Pl. V. fig. 6.) 


BRIGHTWELL, ON RHIZOSOLENIA. 95 


3. Rh. setigera.— Frustule five to fifteen times longer than 
broad ; transverse lines obscure ; terminal bristle as long as 
the frustule ; colourless, of glassy transparency. 

In Ascidize with the two former species. (Mr. Norman.) 
In Noctiluce. (Col. Baddeley.) In Salpz. (Dr. Wallick.) 

This species is distinguished by its extreme delicacy, and 
by the great length of the terminal bristle. (Pl. V, fig. 7). 

4. Rh. alata—Terminal process alate, recurved, blunt; 
colour chestnut brown. 

In Ascidize with Rh. styliformis. (Mr. Norman.) 

This delicate little species, which bears some resemblance to 
a pipe fish, and might have been called “ sygnathoides ” differs 
frout all the others by its blunt, turned-up nose, and its small 
but conspicuous appendages to the terminal process (Pl. V, 
fig. 8). 

In most of the above species, self-division has been ob- 
served. It takes place in or near the centre of the frustule, 
and has the same indefinite character as in Rhabdonema and 
Striatella. The rings of the Rhizosoleniz appear equivalent 
to the annuli in these genera, but, instead of being perfect 
and united by flat surfaces, they are united at acute angles, 
and carry out the frustule to an almost indefinite length. 
The process of self-division is therefore truly diatomaceous. 
Two new calyptriform valves are gradually formed within a 
connecting membrane, as is seen in our PI. V, figs. 6, 7, a, 6. 
These eventually separate, when the old frustule becomes 
two, each division having a new calyptriform end. 

In the genus Isthmia, the frustules of which are trapezoi- 
dal, one valve having a produced angle, we see some resem- 
blance to the Rhizosoleniew, and this would be much 
increased by supposing an Isthmia carried out to ten times 
its normal length, and self-division taking place in the 
centre, as seen in the central fig. in pl. xlvii, ‘ Smith’s 
Brit. Diatom.’ 

In specimens of Rh. setigera a motion has been observed 
resembling that of many of the Diatomacez, the frustule 
proceeding forward in a jerking, tremulous manner, and then 
retrograding. 

Large numbers of Rhizosolenia have been detected in the 
stomachs of Salpze, and they have also been observed floating 
free in the ocean in warm latitudes, their appearance being 
that of little confervoid flakes of exquisite delicacy, but of a 
sufficient aggregation of filaments to be seen by the naked 
eye. The mass appeared (probably from the endochrome) 
of a faint, evanescent, ochraceous colour. 


96 


FiustreLta HispipaA and its DrvreLopMEeNnT. By Prver 
Reprern, M.D. Lond., Lecturer on Anatomy and Phy- 
siology, and on Histology, in the University and King’s 
College, Aberdeen. 


(Read before the Natural History Section of the British Association, at 
Dublin, in August, 1857.) 


Tue Flustrella hispida of Dr. Gray is the Flustra hispida 
of Fleming, and the Plustra carnosa of Dalyell and Johnston. 
It seems to have been overlooked by Mr. Gosse, in his ‘ Marine 
Zoology,’ and to have attracted much less attention than it 
deserves, when its beauty and general distribution are con- 
sidered. 

I have found it abundant on the rocky coast of Kincardine- 
shire, for eleven miles south from Aberdeen; on the Irish 
coast at Howth, Dalkey, and Bray, in the Bay of Dublin, 
and at Wicklow; also in North Wales, at Llandudno. It 
usually grows on the fronds of /ucus serratus, but in the im- 
mediate vicinity of Aberdeen, it is excessively rare on that 
Fucus, but abundant on Chondrus mamiilosus. It forms 
round or oblong, brown, hairy patches, about a line thick, 
which extend completely round narrow fronds, but are con- 
fined to one side of broad ones. It is mvariably encrusting. 
The extent of the coeneecium rarely exceeds an inch on the 
Kincardineshire specimens, but it extends for three or four 
inches on those gathered in Dublin Bay and North Wales. It 
occurs on the Fucus, together with the Alcyonidium hexa- 
gonum (Hinks) and the Cyclowm papillosum (Hassall) ; on the 
specimens of Chondrus the Flustrella occurs with Alcyonidium 
hirsutum. 

The ccoencecium is thick in the centre ; thin, and composed 
of the last-formed individuals at the edges. The cells radiate 
from the centre, and they are imbricated in various degrees 
in different parts, the whole length of the cell, or merely its 
summit, being visible on the surface. The arrangement of 
the cells is variable, but generally alternating. When 
allowed to dry on the plant, the ccencecium presents the 
appearance of a wrinkled, hairy membrane; when it is sliced 
from the plant, and dissected with needles, a large quantity 
of viscid matter escapes from its cells. 

The wall of each cell is set with rigid, reddish-brown, 
pointed and slightly curved hairs, very numerous, and, for 
the most part, occupying the whole circumference in the 
Kincardineshire specimens, but very few in number, and set 


REDFERN, ON FLUSTRELLA HISPIDA. 97 


in a semicircle over the summit of the cells, in the specimens 
from Dublin, Wicklow, and North Wales. 

In the Kincardineshire specimens, the young cells have 
five to seven or nine hairs in a semicircle over their summits, 
and two or three only on each side. The older cells have 
hairs distributed uniformly over their whole circumference, 
their lateral septa often presenting eight to twelve or more 
hairs with their roots closely packed together, one half 
haying their points directed over the cell to the right of the 
group, the other half having theirs turned over that to its 
left. One of the lateral hairs on each side often reaches 
across the cell at the lower margin of its aperture, but no 
hair of any kind grows in any other position than those above 
indicated.* 

In the specimens from the Irish and Welsh coasts, the 
summit of the cell has often no more than three hairs upon 
it, the usual number being five to seven; the sides and base 
of the cells are often entirely devoid of hairs, the lateral 
septa occasionally presenting a patch of two or three. So 
far as I am able to judge from the examination of a large 
number of specimens, there is always a wide difference in the 
number of hairs on the Kincardineshire specimens and those 
gathered further south, this difference being the more re- 
markable, because an inverse ratio maintains between the 
number of hairs and the extent of the coencecium in the two 
series of specimens. JI am anxious that the attention of 
naturalists should be directed to this occurrence, because it is 
possible that the functions of the hairs may be determined 
by observations of the number and character of the hairs of 
the same species, growing under different circumstances. 

The aperture of the cell is somewhat quadrangular—dis- 
tinctly so during the protrusion of the polypide. The charac- 
ters of the cells, their hair sand apertures, are shown in Pl. 
IV, figs. 1, 2, 3, and 3 dis.+ 

The polypide, when healthy, is easily removed from the 
cell with its digestive viscera entire, as in fig. 4. The number 
of tentacles I found to be twenty-eight in all but one of a 
large number of instances, in which I counted them with 


* Tn old and mech imbricated specimens the hairs on the sides and base 
of the cells are best shown by slicing the ccencecium from the plant, and 
dissecting the cells asunder by needles. By this method the polypide may 
also be easily removed from its cell in so perfect a state that it will live for 
many hours, showing the effects of ciliary motion more beautifully perhaps 
than in any other instance whatever. : hed. ; 

+ The subsequent observations were all made on Kincardineshire speci- 
mens. 


98 REDFERN, ON FLUSTRELLA HISPIDA. 


great care, by the aid of the camera lucida; in the single 
instance there were twenty-seven. Each tentacle is hollow, 
covered by a thick layer of ciliated epithelium, easily de- 
tached. It is quite remarkable how rapidly these epithelial 
cells become distended and destroyed when fresh water is 
added; and as this is the case also with the cells of other 
parts of the animal, it is not surprising that fresh water 
instantly destroys it. Fig. 5 represents a portion of a 
tentacle with its epithelium in the natural state; fig. 6 
the tentacle divested of its epithelial covering ; and fig. 7 
shows the action of fresh water upon the epithelial cells. 

The pharynx and cesophagus are lined throughout by 
ciliated and columnar epithelium. The stomach is separated 
from the oesophagus by a distinct and complete valve which 
never allows the alimentary matters to regurgitate. The 
cesophageal portion of the organ is cylindriform, the body is 
greatly dilated having a pouch-like dilatation on its great 
curvature, and being gradually narrowed towards the pyloric 
aperture, where the stomach can be shut off from the intes- 
tine, apparently by a contraction of its muscular wall (py- 
loric valve). Over the whole of the stomach, the epithelial 
cells contain a nucleus and deep-red, granular contents. 
Those of the cul-de-sac, and in the great curvature, and those 
at the pyloric end, are ciliated; but no cilia are observable 
in the other parts, nor in any portion of the intestine. The 
action of the cilia of the stomach is remarkably beautiful 
when viewed under the microscope, and produces a rapid 
rotatory motion of the contents of the cul-de-sac, or of the 
pyloric end, in the axis of these parts respectively. 

To the stomach succeeds a dilated portion of the intestine, 
where the alimentary matters are retained for some time, and 
converted into elongated consistent pellets. The wall of this 
portion of the canal has an epithelium, the cells of which 
contain deep-red granules like those in the stomach-cells, 
but much fewer in number. Beyond this the intestine is 
considerably contracted, and its wall becomes so thin that it 
is often torn during the dissection, in tearing away the tu- 
bular sheath of the tentacles, formed of the soft, protrusible 
portion of the cell. Through this membrane the anus opens 
externally. I have never noticed the discharge of alimentary 
matters, except at the moment of protrusion of the tentacles, 
when the pellet to be discharged escapes from within the 
crown of tentacles, and commonly falls through between two 
of them to the exterior. 

Muscular system.—The retractor muscular fibres are best 
seen, im situ, in preparations which have been preserved in 


REDFERN, ON FLUSTRELLA HISPIDA. 99 


spirit, in which they are remarkably distinct. The insertion 
of the great retractor into the lophophore, the pharynx, and 
cesophagus, is beautifully seen in the animal removed from 
its cell by dissection, as in fig. 4. 

The great retractor muscle consists of a long ecylindriform 
bundle of fibres, stretching from the deepest part of the cell 
over the stomach, to reach the cesophagus, pharynx, and 
lophophore, into which the fibres are inserted. Another 
bundle of much shorter fibres extends from the side of the 
cell, near its bottom, to the cul-de-sac of the stomach, into 
which it appears to be inserted, drawing this part of the 
organ downwards and towards one side when in action, and 
thus assisting i folding the parts of the alimentary canal 
upon each other, that they may be easily accommodated in the 
interior of the cell. Yet neither these fibres nor any of 
those of the great retractor muscle remain attached to 
the stomach of the polypide withdrawn from its cell. I 
have examined the perfect stomach thus removed in at 
least twenty instances, and in none have I seen a single 
fibre attached to the wall of the stomach, whilst, in every 
case, the torn pharyngeal fibres remain connected with 
it. Four or five distinct bundles of muscular fibre stretch 
from the interior of the cell, at different points, to the 
polypide; passing transversely to the axis of the cell. 
Other bundles of at least two different muscles extend from 
the upper part of the interior of the cell to the mvaginated 
portion, which forms the sheath of the tentacles during the 
retraction of the polypide. The longer of these bundles is so 
much relaxed durig complete retraction, that it is bent upon 
itself. 

During retraction, the csophageal end of the stomach is 
rapidly drawn down to the bottom of the cell on one side, 
the cul-de-sac of the organ to the bottom on the other side ; 
the pyloric end of the stomach is folded upon the upper cur- 
vature, the pyloric orifice being brought very close to the 
cesophageal; the intestine is bent upon the pyloric end 
until the two lie parallel; and the tentacles are folded in a 
somewhat spiral manner, close to the intestine which lies by 
their side. Thus the cesophageal and pyloric ends of the 
stomach, and the dilated commencement of the intestine, are 
folded and lie parallel to each other directly across the axis 
of the cell, in the state of retraction, whilst they lie with their 
axes parallel to that of the cell, in the state of protrusion of 
the polypide. The act of retraction is sudden and rapidly 
completed, like that of voluntary muscles in general; the 
act of protrusion is performed very slowly, as if the tenta- 

VOL. VI. I 


100 REDFERN, ON FLUSTRELLA HISPIDA. 


cles were gradually distended with fluid, and the body slowly 
pressed out of the cavity of the cell. 

By dissection, ova or statoblasts are obtained in great 
numbers, presenting the appearances represented in figs. 8 
and 10, and consisting of an outer envelope, contaming a 
number of clear and highly refractive nucleated cells, and an 
opaque, reddish, spherical mass, composed of cells with red 
granular contents. When some of the contents of these 
bodies have escaped, their structure is much more easily ex- 
amined, as in fig. 9. None of those figured possessed cilia. 
The cilia belong to a membrane, which is placed outside the 
two capsules figured, and separated from the outer of these 
by a finely granular mass. Only one of these bodies was 
observed to have cilia, amongst twenty or thirty carefully ex- 
amined to determine their presence or absence. 

Development.—My reasons for believing that the animal 
whose development has been examined is the same as the one 
just described are :—lst, that it grew on the wall of an 
aquarium, in which there were numbers of specimens of 
Flustrella growing on Chondrus mamillosus, and, so far as 
I could judge, no other which could be mistaken for it ; 
2d, that on the cell of the second polypide hairs grew of 
a similar character to those shown in figs. 1, 2, and 3; 3d, 
the character of the tentacular crown, and the number of 
the tentacles, as far as it could be determined in a bad posi- 
tion for counting them, and the appearance of the digestive 
organs, were exactly such as occurred in the creature figured 
from 1 to 10. 

On the 3d of July, 1857, I first observed a solitary poly- 
pide in its cell, on the wall of an aquarium. It was appa- 
rently in perfect health, alternately protruding and with- 
drawing its beautiful, bell-shaped crown of tentacles. The 
elegance of the form of the bell, and the number of its 
tentacles, led me to compare it with the specimens growing 
on Chondrus in the same vessel, and the result was, that I 
could find no difference between them. On this occasion I 
did not notice any projection of the wall of the cell for the 
formation of a gemma. 

On the 4th of July, a definite projection of the wall was 
observed (fig. 11) ; two days later the projection had imcreased 
in size considerably, and it presented externally a protruded 
portion of the wall of the original cell, and in its interior a 
striation slightly radiating towards the surface, the striz 
being produced of rows of highly refractive globules (fig. 21.) 
On the evening of this second day, the body of the polypide 
was. visible, as a small cone, at the deepest part of the 


REDFERN, ON FLUSTRELLA HISPIDA. 101 


striated mass, and on the third day it had become much 
more distinct, whilst the gemma appeared to be encroaching 
on the old cell, and the striated mass had approached the 
surface (fig. 13). Witha view of facilitating the examination, 
a small mirror, the framework of which had been recently 
coated with gold size, was introduced into the aquarium. 
Shortly afterwards, the tentacles of the polypide (fig. 11) 
were observed to be bent at various angles, and to hang 
loosely, as if they had been broken, resuming thei natural 
appearance at intervals. The polypide protruded itself but 
rarely, and never recovered its healthy characters, dying four 
days subsequently. I believe that it was injured by the 
gold size. 

On the fourth day of the formation of the gemma, it pre- 
sented a yellowish striated band at its deepest part, appa- 
rently the first trace of its retractor muscle. On the same 
day, traces of the formation of three other gemmee were seen, 
as in fig. 14, but their development was speedily arrested, and 
they were not again observed. 

On the seventh day, the new polypide presented the form 
of a bent tube, the striation near the surface remained, and 
between it and the bent canal, representing the body of the 
animal, there was a clear space faintly separated into bands 
by indistinct striz (fig. 15). These ultimately became the 
tentacles. On this day, four distinct and blunt hairs were 
observed to have formed on the wall of the cell of the new 
polypide. 

On the eleventh day, the gemma had considerably in- 
creased in size, and presented a nipple-like membranous 
prominence. The polypide was observed shrinking in its 
cell on the application of a bright light. The hairs, which 
were blunt at their ends on the seventh day, had become 
pointed. The perigastric space was quite distinct. The re- 
fractive globules, producing the striation near the surface 
had gradually diminished in number, and formed a thin 
layer between the tentacles and the surface. This state was 
figured on the twelfth day, as in fig. 16. 

On the thirteenth day, the apex of the cell had become 
much thinner, and presented the appearances represented in 
the drawings (figs. 17 and 18), sketched by the aid of the 
camera lucida, when the polypide was retracted and protruded. 
The tentacles were much longer and more distinct, the rows 
of highly refractive globules between the tentacles and the 
surface were greatly diminished in number and size, and the 
perigastric space was clearer. The condition of the polypide 
at this timeis so graphically described by the Rev. T. Hincks, 


102 REDFERN, ON FLUSTRELLA HISPIDA. | 

in a paper in the eighth volume of the‘ Annals and Magazine of 
Natural History,’ that I can add nothing to his account of it. 
I regret that I was not aware of the existence of this paper 
until after my opportunity of observing the creature had 
passed away. Mr. Hincks says :—“ Imperceptibly the body 
of the polype shapes itself within the mass. The tentacles . 
are first visible.* Soon violent convulsive movements are 
seen within. The front part of the cell is frequently pushed 
out with much apparent force, so as to form a neck of con- 
siderable length, and then suddenly retracted. There is no 
appearance of an opening at this time. The tentacles become 
very restless, and bend themselves about as if trying their 
powers, and impatient of confinement. Gradually the parts 
become more defined ; the elongation and retraction of the 
fore part of the cell contimue, and, at length, the polype 
breaks from its captivity.” 

On the fifteenth day, the polypide protruded fully, and its. 
tentacles expanded freely. The wall of its cell was beauti- 
fully transparent, and admitted a full examination of the 
viscera, now receiving the alimentary matters. On the 
seventeenth day, the drawings 19 and 20 were made. In the 
state of protrusion, the lophophore and anus were carried 
outwards, and the alimentary canal stretched, owing to the 
stomach being drawn but little away from the bottom of the 
cell, whilst the other parts were shifted extensively. Ciliary 
motion was distinct on all the parts on which it is observed 
on the adult polypide. In the state of retraction, the qua- 
drangular state of the aperture of the cell was distinctly ob- 
served ; the tentacles were folded somewhat spirally upon 
each other; the cesophageal end of the stomach was drawn 
down to the bottom and side of the cell, and the pyloric end 
folded over it, the pyloric orifice being carried towards the 
same side, together with the dilated commencement of the 
intestine, which was laid parallel to the pyloric end of the 
stomach, and directly across the direction of the cell. 

Some appearance of the formation of a gemma occurred on 
the wall of this second cell, as in fig. 20, but it became no 
further developed, and the second polypide itself was found 


dead on the twenty-seventh day of its existence, to my very 
great regret. 


* When I first saw the striated mass beneath the surface of the gemma 
I supposed that it was the early stage of the formation of the tentacles, but 
I subsequently found that they formed beneath it, and that they were not 


distinct until after the body of the polypide had assumed the decided form 
of a bent tube. 


103 


TRANSLATIONS. 


Abstract of Remarks on the Marernat Bontzs of the Mepus2. 
j By Professor C. GEGENBAUR. 


(Miiller’s ‘Archiv,’ 1856, p. 230.) 


“ Tuxse bodies,” the author observes, “ afford better syste- 
matic characters for the classification of these animals than 
can be derived from the form of their bodies or the relations. 
of their tentacles.” 


He describes:—A. Marginal corpuscles of the lower 
Medusz. 


This class includes the forms termed by Forbes “ naked- 
eyed,” embracing the Aiquoride, Alginide, &c., all probably 
medusoid forms of polypes. In these Medusze two kinds of 
marginal bodies are met with. Both are placed at the border 
of the disc, and are either in intimate relation with the base 
of the tentacles, or constitute small eminences between those 
organs,—in one case supported on long peduncles. One form 
presents the appearance of vesicles containing earthy con- 
cretions, whilst the other represents merely a deposit of 
colouring matter, sometimes enclosing a refractive body. 


a. Vesicular marginal bodies. 


These are found, first, in all the Geryonidz and Aiginide— 
probably also in the Auquoride ; and secondly in some of the 
medusoid forms at present included under the genus 
Thaumaniias. 


Tn all the true Oceanide, as well as in the Thaumantiadze— 
both of which families appear to be characterised by the 
presence of pigment-spots at the base of the tentacles—no 
trace of vesicular marginal bodies is found to exist. 

The vesicles are of a rounded, elliptical or elongated shape, 
and always have thin walls, apparently continuous with the 
integument of the Medusa, and enclosing the cavity on all 
sides. Internally this wall is ined with an epithelium, com- 
posed of smooth polygonal cells, which are not visible, how- 
ever, except upon the addition of acetic acid. The vesicle 
contains one or several spherical or oval, motionless concre- 
tions, surrounded with a transparent fluid. The concretions, 
to judge from the effect upon them of acetic acid, consist in 
part of carbonate of lime; and after this is dissolved, an 


104 GEGENBAUR, ON MEDUS. 


organic residue is left retaining the original form of the 
concretion. Gegenbaur has never observed crystalline forms 
or crystals. 

The number of these marginal vesicles is constant in the 
Geryonide, and also in the minute medusoid forms resembling 
Thaumantias, and which should probably form a distinct 
family from the true Thaumantiade. In the Auginidze their 
number is very variable, and in this group the maximum in 
this respect is probably reached, viz., about 60; though even 
in this family exceptions exist. 

The position of these bodies always indicates an intimate 
relation to the gastro-vascular system, although the cavity of 
the vesicles does not, as might be supposed, communicate 
with the interior of the gastric canals. This relation is 
especially evident in the Cuninide, in which the marginal 
vesicles are always sittiated at the extremities of the gastric 
sac, and never in the interspaces. 

In the Geryonide a marginal vesicle is seated at the base 
of each tentacle. In some species of the family Aiginide 
the vesicle is seated in a depression at the summit of a conical 
eminence, composed of distinct cells, each of which, in a form 
allied to gina, supports a long descending ciliwm. 

Gegenbaur has never witnessed ciliary movement within 
the vesicles, nor in fact motion of any kind, except what 
might be referred to endosmotic action. In this he agrees, 
he says, with all his predecessors, except Kolliker, who 
describes in a species of Oceania the existence of cilia in the 
marginal bodies,—an observation the correctness of which 
Gegenbaur does not doubt, but supposes it to refer to Oceania 
marsupialis (Carybdea marsupialis, Peron), whose marginal 
bodies present very remarkable peculiarities, which he after- 
wards discusses. 

If the rather large marginal vesicles of Geryonia be ex- 
amined, it will at once be seen that the concretion is not free 
in the vesicle, but connected to the wall by means of a short 
peduncle, from which, in fact, a delicate membrane extends 
over and encloses the concretion entirely. Repeated obser- 
vation will occasionally detect a much thicker investment, 
within which, besides the concretion, are contained minute 
molecules, and an oval or rounded corpuscle, resembling a 
nucleus. In fact, there is nothing opposed to the notion that 
the concretion is formed in the secreting cavity of a parietal 
cell which projects into the interior of the vesicle, m the 
same way that other concretions are formed in the lower 


animals, as for instance the renal concretions of the Gastero- 
poda, &e. 


GEGENBAUR, ON MEDUSZ. 105 


If this be the true state of things, there can be no question 
as to the non-existence of motion in the concretions, and in 
great measure the analogy fails, which would place the 
marginal bodies of the Meduse in the same category with 
the auditory organs of the Acephala and Cephalopoda. 


6. Pigment-spots (ocelli). 


Coloured spots on the base of the tentacles occur only in 
the Oceanidz and Thaumantiad, both of which families 
(certainly the former) are medusoid forms of polypes. Con- 
sequently, except in Oceania turrita, coloured spots and mar- 
ginal vesicles are not found to coexist. 

The spots themselves consist of dense agglomerations of 
yellow, red, brownish-red, or black pigment-cells, placed upon 
a more or less prominent elevation on the base of the 
tentacle. Except in Tiaropsis, their number corresponds 
with that of the tentacles. 

In Lizzia, Bougainvillea,—Oceanide, with the tentacles 
disposed in groups,—the ocelli are always situated on the 
under side of the tentacles in the form of a crescent. 

In Cladonema and the allied Eleutheria of Quatrefages, a 
spherical, highly refractive corpuscle is lodged in the midst 
of the pigment. In Eleutheria this body is of considerable 
size, and projects above the surface. 


B. Marginal bodies of the higher Meduse. 


In the lower Meduse we have seen the two forms of 
marginal bodies existing in distinct families, but in the 
higher or steganophthalmatous group we see indications of 
the union of the two into a single organ. 

In the simplest form of these bodies, as in Pelagia and 
Cassiopeia, they constitute vesicles of an oval form, somewhat 
acuminate at the free end, and wider at the opposite, sup- 
ported on a short stem in the incision and between the lobes 
of the disc. Immediately above the notch in which the 
marginal body is lodged, runs a canal communicating with 
the contiguous prolongation of the gastric cavity. The canal 
at this point is slightly dilated and furnished with distinct 
walls. It enters the stem of the marginal body, running 
downwards in it for more than one third of its length, ulti- 
mately curving round nearly at a right angle with the longi- 
tudinal axis of the marginal vesicle. 

The marginal body itself encloses an oval cavity also 
surrounded by a well-defined layer of tissue. The curved 
canal of the peduncle opens into this space, which would, in 
fact, represent a sudden dilatation of it. Thus, in the 


106 GEGENBAUR, ON MEDUS&. 


higher Medusze, there is a communication between the 
marginal vesicle and the gastro-vascular system, a fact dis- 
puted by Kélliker. The interior of the vesicle, like that of 
the canal, of which it is, as it were, a derivation, is lned 
with a very delicate ciliary investment, by means of which a 
constant circulation of the contained fluid is maintained. 
Kolliker and others have described an opening on the upper 
side of each marginal vesicle, through which the ampulla 
above described would communicate with the surrounding 
medium; but Gegenbaur denies altogether the existence of 
any openings of the kind. 

At the free end of the marginal body, and constituting 
nearly its whole apex, is placed an oval sacculus, 0°14’ long 
by 0:09’ broad, closely filled with prismatic crystals, and 
which probably represents the most important physiological 
portion of the organ. The membrane of this sacculus is 
indeed thin, though possessing a certain resistance. At the 
sides and distal end it is enclosed by the walls of the marginal 
body itself, which are here somewhat thinned, whilst the 
part corresponding to the ampulla is covered with the ciliary 
lining of the latter. There is no communication between the 
ampulla and the crystalline sacculus. Gegenbaur has never 
perceived any movement in the crystals, and denies the 
existence of cilia in the sacculus containing them. The 
crystals themselves are six-sided prisms, obliquely truncated 
at each end; in length and number they vary very much. 
The longest measure 0:02'". They appear to be insoluble in 
acetic acid. 

Gegenbaur then proceeds to describe the unusual forms of 
marginal bodies which exist in species termed by him 
Ephyropsis,* and probably belonging to the genus Nausitho, 
of Kolliker,+ and in Carybdea marsupialis, in both of which 
Meduse, moreover, the ocelli contain sperical, refractive 
bodies. 

After discussing the question concerning the function of 
these bodies, Gegenbaur inclines to the opinion, that the 
coloured spots, especially when furnished with a spherical 
refractive corpuscle, are of the nature of visual organs, whilst 
he throws out the supposition that the other kind may be 
excretory. Relying chiefly upon the absence of motility in 
the concretions or crystals, and of cilia in the cavities in 
which these bodies are lodged, he attempts to show the im- 
probability of their being auditory organs. 


* “Comptes rendus,’ t. xxxviii. 
+ ‘Zeits. f. Wiss. Zool.,’ Bd. iv, p. 323. 


107 


Mopes of Dretrerminine, by the Use of the Microscorz, the 
Rerracrive Inpex of Fiurps. 


(Freely translated from the Dutch of Professor Hartine, of Utrecht. 
By Wixtiam Rosertson, M.D., F.R.C.P.E. See ‘ Het Mikroskoop,’ 
Tweede Deel, b. 200.) 


A KNOWLEDGE of the laws which the rays of light observe 
in their course through refracting media enables us, with the 
help of the microscope, to determine the index of refraction 
of certain substances, to which, on account either of their 
small quantity or of their insufficient transparency except 
when in layers of extreme thinness, the ordinary methods are 
inapplicable. 


I. Sir David Brewster’s Method. 


It is many years since Brewster first used the microscope 
for this purpose. His mode of procedure is described in his 
‘ Treatise on Philosophical Instruments,’ Edinb., 1813, p. 240. 
He uses a compound microscope, the object-glass of which is 
a biconvex lens, with sides of equal curvature, and of consi- 
derable focal length. This lens is firmly fixed in the lower 
extremity of a brass ring, which is to be filled with the fluid 
whose refractive power is the subject of examination. The 
upper opening of the brass ring is then to be closed by laying 
on it a circular glass plate with parallel surfaces. The con- 
tained fluid now forms a plano-concave lens, the concavity of 
which rests on the upper side of the biconvex glass lens. 
The object-glass is thus converted into a plano-convex com- 
pound lens, resembling an achromatic combination of flint- 
and crown-glass, but with this difference, that in the former 
the convex surface is directed downwards and the flat surface 
upwards. 

When the biconvex is thus converted into a plano-convex 
lens, its focal length becomes of course considerably aug- 
mented ; and in like manner the distance at which an object 
must be placed in order to be clearly seen through the mi- 
croscope becomes greater. 

That the eye may in the course of a series of observations 
be as nearly as possible in the same state of accommodation, 
Brewster recommends the use of an eye-piece with a wire 
or glass fibre crossing its field, to form a distinct image on 
the retina at the commencement of each observation, and 


108 ON THE REFRACTIVE INDEX OF FLUIDS. 


thus secure the uniform exercise of the same amount of 
accommodating power. 

For the calculation of the index of refraction we must have 
the following data: 

lst. The radius of curvature of the biconvex lens = 7. 

2d. The distance between the biconvex lens and the object, 
when the latter is best seen, and air only is interpo.ag 
between the lens and its covering-plate. This distance = 

3d. The distance between the biconvex lens and theob. ~ 
when the latter is best seen, and the space between lens!&¢ts 
glass covering-plate is filled with the substance under ex and 
nation. This distance = 6. 

If now we make the required index of refraction =n, we 
have the following equation : 


eee pee (C— or ! 

ab 
This formula has been communicated to me by my colleague, 
Van Rees, and I have substituted it for that given by 
Brewster, in which the index of refraction of the biconvex 
lens is assumed as known, which, however, can be the case 
only when such a lens has been made for this express purpose 
of glass whose index of refraction is ascertained before grind- 
ing. 

The advantages of Brewster’s method are, that it is not 
only applicable to fluid bodies, but to such as are so soft as 
to admit of being pressed into the lenticular form, even when 
their degree of transparency is but feeble—a case for which 
we can provide by causing the light to traverse a thinner 
layer of the substance under examination. Different bodies, 
such as wax, pitch, opium, &c., which are in mass absolutely 
opaque, become, when pressed into a thin layer, transparent 
enough to admit of the determination of their indices of 
refraction by this method. 

The disadvantages of the procedure are the following. In 
the first place it requires the adaptation to the microscope of 
a special apparatus, consisting of an object-piece constructed 
for the purpose, and of a very accurate micrometric movement 
for measuring the distance at which the object is seen sharply 
defined. In the second place, the radius of curvature of the 
biconvex lens must be exactly known—one of the most diffi- 
cult of requirements in the case of microscopic lenses. 
Iinally, in the third place, the question arises—‘ from what 
point is the distance of the object to be measured ?” 
Brewster seems to have used the lowest point of the lens as 
his ‘‘ point de départ ”?—but this is not correct, for the true 


ON THE REFRACTIVE INDEX OF FLUIDS. 109 


point, the optical centre, is in the compound lens, and at a 
depth varying with the thickness of the layer and refracting 
power of the fluid which constitutes a part of the plano-con- 
vex lens. Henceit is hardly possible to measure the distance 
of the object with the degree of accuracy required for the 
subsequent calculation. 


Il. Harting’s Method. 


The following method may be followed with any micro- 
scope and without the addition of special apparatus ; and 
although comparatively limited in its application, which is _ 
restricted to certain fluids, it affords indications of extreme 
exactitude when due attention is paid to the manipulation. 
It is free from the above-mentioned disadvantages of 
Brewster’s method, and has the further recommendation that 
a very small quantity of fluid is required for each observation, 
even a few milligrammes amply sufficing for the determination 
of the index of refraction. 

This method is founded upon the different dimensions of 
images of the same object placed at like distances from air- 
bells of like size in fluids of different refractive power. That 
this difference in the size of the images is rather considerable, 
the following examples will show: 


Water . n=1:336 Diameter of image = 1000 
Sulph. acid . > L416 ah 3 =e fo 
Canada balsam ,, 1°504 95 es == 5o2 


To enable us to calculate the index of refraction, it is 
necessary that there should be— 

Ist. A thin layer of the fluid between two plates of glass 
with parallel surfaces ; also some air-bells in the fluid to act 
as dispersing lenses and form images of objects situated 
beneath them. To prepare the fluid for the observation, let 
a drop be placed on a thin glass plate, and some air-bells 
formed by blowing air into the fluid through a small glass 
tube drawn out very fine in the blowpipe flame. <A small 
ring of paper is next laid round the drop, and on its surface 
a thin glass covering-plate is placed. It will then be found 
that some of the air-bells have lost their spherical form and 
are consequently useless for the purpose in hand. This will 
be quickly seen from the distortion of the images which they 
form—there wi!l, however, always be present a few which will 
exhibit correct and sharply defined images. The thickness 
of the glass object-plate should not exceed 3th of a milli- 
metre = ;45th of an inch nearly: for a thicker plate would 
exercise on the course of the rays an influence which in the 


110 ON THE REFRACTIVE INDEX OF FLUIDS. 


subsequent calculation could not be neglected. An ordinary 
thin glass covering-plate may be conveniently used. 

2d. It is necessary to provide an object, the diameter of 
which is very exactly known—the most suitable is a strip of 
metal coloured white. This strip should be placed beneath, and 
parallel with, the stage of the microscope, and should be so 
arranged on a proper holder that its middle point shall coin- 
cide precisely with the prolongation of the optical axis of the 
instrument. 

3d. It is necessary to know, as nearly as possible, the dis- 
tance between the upper surface of the object and the air-b>ll. 
In my investigations, I prefer a fixed distance of 100 milli- 
metres, on account of the convenience of this round number 
in calculation. The construction of most microscopes also 
renders this aconvenient distance. Between the distance and 
the diameter of the object a certain ratio should be observed. 
If the latter be more than one fifth of the former a correction 
of the final result becomes necessary, for in consequence of 
the excessive obliquity of the rays proceeding from the 
margins of the object, the difference between their angles of 
incidence and of refraction becomes too sensible to be neg- 
lected. 

4th. The microscope being so arranged that the object is 
brought distinctly into view, the diameter of the air-bell and 
of the image of the object below it are to be successively 
measured; and in doing so it will be of course necessary to 
alter the focus of the instrument slightly, the margins of the 
air-bell and the image lying in different planes. 

As the accuracy of the result in great measure depends 
upon these two measurements, it 1s scarcely possible to bestow 
too much care in taking them. For the methods to be 
followed in this stage of the observation, I refer to the 
chapter on Micrometry.* I must not neglect to add that 
these measurements should be made by reflected light—if 
transmitted light be used, the influence of diffraction causes 
the results to be somewhat too small. It is also advisable 
that the strip of metal used as an object should be of a white 
colour. 

It is essential that the successive measurements of air-bell 
and image should be made rapidly, both in order to obviate 
the influence of changes of temperature, and because the 
gradual absorption of air by most fluids, and especially by 


* In the ‘Monthly Journal of Medical Science,’ May, 1852, p. 453, a 
very full abstract of this chapter will be found. The most exact methods 
are those in which the screw-micrometer eye-piece or the plan of “ double 
vision” are used. (T.) 


ON THE REFRACTIVE INDEX OF FLUIDS. lil 


those of organic origin, causes the diameter of the air-bell 
after a certain time to become notably diminished. We 
must not therefore rest satisfied with a smgle measurement, 
but take each set of dimensions again and again, and use in 
the final calculation the mean results of all. 

Let us now suppose : 


Distance between object and air-bell 
Diameter of the object 

Diameter of image > 

Diameter of the air-bell 


I fl Wl 


a 
b. 
c. 
d 


The index of refraction will then be obtained by means 
of the following formula, for which I am indebted to my col- 


league, Van Rees: 
i b—c)d 
= = + Ae ee 


4ac 


But as c may be regarded as infinitely small when com- 


pared with 4, 
1 1 bd 
as Vv; * Fae 


The use of this formula enables us to deduce the refractive 
index with certainty to the third decimal place, but only 
when the above-mentioned conditions are attended to, and 
the final mean of several measurements is used as the basis 
of calculation. When a thicker object-plate, and especially 
when a larger object is used, there arises the necessity for 
different corrections, which cannot be neglected, and which 
render the computation troublesome and its result less 
exact. 

If, as in the arrangement which I have recommended, 


a =100, b= 20, or, in general, if 4 3 then, 


n=5 a: Vite 20 


Some results obtained by this method may be here sub- 
joined, in order that the reader may form an estimate of the 
degree of accuracy of which it is susceptible.* 


* The first two examples taken from Harting are all that we give 
here. (T.) 


112 ON THE REFRACTIVE INDEX OF FLUIDS. 


1. Aqueous Humour from Cow’s Eye. 


By measurement No. l - m=1°3495 

” » ify \eapaleaam 
» 13494 
», 1°3496 
3, 1°38465 


OE ) 


By mean ..,. + *osto-gf=-djoaen 


Extreme difference of measures . . = 0:0039 
Probable error of mean = 0:0005 


2. Vitreous Humour of same Eye. 


By measurement No.1] . n=13412 

5B) » 2 »” 13421 

” » O 5B) 13474 

” be ig Fite, Wes 

»” »” 5 ” 1°3426 

By mi¢an:) © 92) Sy sed Sy a date 
Extreme difference of measures . . = 0:0062 
Probable errorofmean. . . . . == 00-0007 


III. Moser’s Method. 


An account of this method is contained in the ‘ Reper- 
torium der Physik,’ v, p. 395. Moser uses an object-piece 
of long focus, taken from a common reading-microscope, and 
fixed at one end of a tube of at least fourteen inches in 
length, to the other extremity of which an eye-piece is 
adapted. The refractive index of a transparent plate with 
parallel surfaces, or of a layer of fluid, is then found by the 


] 
following formula: x=? (1 —*), When an object is 


brought into focus, and the refractive medium then inter- 
posed, the tube must be lengthened, or rather the object- 
glass withdrawn to a certain distance, in order that a distinct 
view of the object may be obtained. The difference between 
these two focal distances is then called 2, the thickness of 
the interposed refractive medium is termed 7, and the index 
of refraction = 7. 


IV. Bertin’s Method. 


This method was communicated to the French Academy, 
through Regnault, in April, 1849, and a full account of it 


ON THE REFRACTIVE INDEX OF FLUIDS. Lis 


was published by Bertin himself in the ‘Ann. de Chimie et 
de Physique,’ 1849, xxvi, p. 288. To determine the refrac- 
tive index of a plate of glass, he proceeds as follows. A 
micrometer is used as an object, and its amplifications ob- 
served—first, as it lies on the glass plate; second, as it lies 
beneath it; and, third, as it rests on the stage without the 
interposition of the plate. In the course of these observa- 
tions the olject-piece must remain a fixed point, and the 
necessary motion be given to the eye-piece only. The suc- 
cessive amplifications, in the above order, are termed G, y, g, 
and the formula for finding the index of refraction is 


ene od 

meet Gly 

When the plate is very thick, it is better to compare it with 
another whose index is already known. Then, 


( -) i 1 
Saleh Sse eee 


This method, like all the others which we have had occasion 
to describe, is also applicable to fluids. It is said, that its 
possible error cannot exceed 1 in the second place of deci- 
mals. 


®_ 
| 
aaa 
py 

| 

Sle 
ea 
S 1 
| 

be 


Note.—Of the comparative value of these four methods 
I have had no opportunity of judging; but on applying 
the second to the determination of the refractive power of 
water, turpentine, castor oil, and other fluids, I have found 
its results very uniform and satisfactory. (Trans.) 


114 


REVIEWS. 


Archives of Medicine. Edited by Lionrt Bears, M.B. 
London: Churchill. 


Tis is the first number of a new medical periodical, but 
how often it is to appear the editor does not inform us. ‘The 
object of the editor is to publish papers of a more thoroughly 
scientific character than are usually found in medical perio- 
dical literature, and to have these papers freely illustrated. 
The subjects on which he wishes to receive papers are as 
follows : 


1. Practical clinical observations. 

2. Original researches in Physiology and Pathology. 

3. Chemical and Microscopical examination of the solids 
and fluids of the body. 

4. Descriptions of scientific processes. 

5. Condensed reports of researches published elsewhere. 


The distinguishing features of this first number are the 
papers devoted to chemical and microscopical research and 
the accompanying lithographic plates. Of course microsco- 
pical examination is only one means pursued in the investiga- 
tion of healthy or diseased structures, and in most of the 
papers in this first number we have observations recorded by 
the use of the microscope. As an example of the papers we 
republish one by the editor. 


“On the Manner in which the Drawings illustrating the Papers have been 
made, and of obtaining Lithographs from Microscopical Drawings. 


“JT have always felt it very desirable that the description of scientific 
observations should be curtailed as far as is consistent with accuracy and 
perspicuity in the statement of the results, and it is my desire, as far as 
possible, to see drawings take the place of long and necessarily tedious 
descriptions of observations. Instead of alluding to the dimensions of an 
object in the text, the reader will be referred to the scales appended to every 
plate, and with the aid of very little trouble, the diameter of every object 
depicted may be readily ascertained. For all ordinary purposes it is only 
necessary to compare roughly the size of the drawing with the scale magni- 
fied in the same degree as the specimen itself, but in those instances where 
great accuracy is important, a pair of compasses nay be used. 

“In comparing the representation of the same object delineated by different 
observers, it will be often found that great confusion has been produced in 


BEALE, ON OBTAINING LITHOGRAPHS. 115 


consequence of the magnifying power of the object-glass not having been 
accurately ascertained, and an object said to be magnified in the same degree 
by two authorities is not unfrequeutly represented much larger by one than 
by the other. This arises from the magnifying power of the glasses not 
having been accurately ascertained. 

“1 cannot too strongly recommend all microscopic observers to ascertain 
for themselves the magnifying power of every object-glass, aud to prepare, in 
the manuer presently to be described, @ scale of measurement by which the 
dimensions of every object can be at once ascertained. 

“The inconvenience of not being acquainted with the number of diameters 
which any object represented in a drawing is magnified, has been often felt ; 
for without this it is impossible to judge of its real size. And, on the other 
hand, the annoyance of reading a long description of minute objects, differ- 
ing slightly in size from one another, the dimensions of which have been 
accurately noted, is very great; while no corresponding advantage is de- 
rived from such minute measurements. The text becomes occupied with a 
multitude of figures of but little interest to the reader. At the same time, 
it is very desirable that the careful observations of different persons should 
be readily comparable with each other. Elaborate researches are not un- 
frequently deprived of much of their value in consequence of measurements 
having been carelessly taken, or the magnifying power of the glasses 
wrongly expressed. 

“The plan of appending to every microscopical drawing a scale magnified 
in the same degree as the object represented, supersedes the necessity of 
giving measurements in the text, while it is free from any of the objections 
above referred to. I propose to describe briefly a very exact, and at the 
same time a very simple, method of applying scales to microscopical drawings. 
All the drawings illustrating the editor’s papers may be measured by the 
scales at the bottom of the page, and he strongly recommends all contri- 
butors to follow the same plan. 

“To carry out this it is necessary to ascertain the magnifying power of 
every object-glass, and to be provided with a stage micrometer divided into 
LO0ths and 1000ths of an inch. 

“ Mode of ascertaining the magnifying power of the object-glass.*—A glass 
micrometer divided into 100ths of -an mch is placed in the focus of the ob- 
ject-glass of the microscope, which is arranged horizontally. The neutral 
tint glass-reflector is fitted to the extremity of the eye-piece, and the light 
carefully arranged so as to render the micrometer lines distinctly visible. 
Care must, however, be taken that the distance from the object-glass to the 
reflector is the same as from the latter to the paper beneath it, upon which 
the magnified micrometer lines may now be traced. A four- or six-inch 
scale accurately divided into 10ths of an inch is now applied to the magnified 
LOOths of an inch, and the magnifying power of the glass is at once ascer- 
tained. Suppose each magnified 100th of an inch covers 1 inch, the mag- 
nifying power will be 100 diameters, if an inch and 3 tenths 130 diameters, 
if 4 tenths of an inch 40 diameters, and so on, each 10th of an inch corre- 
sponding to a magnifying power of ten times. 

“Tf we wish to ascertain the magnifying power of one of the higher object- 
glasses, a micrometer divided into 1000ths of an inch should be employed 
instead of the one just alluded to. In»this last case, each tenth of an inch 


* «This mode of measuring is alluded to in several works on the micro- 
scope, but the editor considers it sufficiently important to repeat here, 
especially as the drawings illustrating papers published in the ‘ Archives’ 
have been copied in this manner.” 

VO Vil. K 


116 BEALE, ON OBTAINING LITHOGRAPHS. 


upon the scale corresponds to a magnifying power of one hundred, instead 
of ten diameters. Any fractional parts can be readily estimated if we have 
a very accurately divided scale. This process must be repeated for every 
object-glass, as well as for each different eye-piece employed with the several 
objectives. 

“1 ascertain the Diameter of an Object.—If an object be substituted for 
the micrometer, and its outline carefully traced upon paper, its dimensions 
may of course be easily ascertained by comparison with the micrometer lines, 
The magnified power used being the same in both cases. 

“Tn order to apply this plan to microscopical drawings generally, the fol- 
lowing seems to be the simplest method of proceeding, and saves mucli 
trouble. Scales are carefully drawn upou gummed paper; the magnifying 
power, and the micrometer employed, being written against them as repre- 
sented in the plates. If a number are drawn together one of the rows can 
be cut off and appended to the paper upon which the drawing, magnified of 
course to the same degree, has been made. This is the plan | have followed 
in all the drawings which illustrate my observations, and the scales have 
been copied in the lithographs. All magnifying glasses of the same focus 
do not magnify in precisely the same degree, so that it is necessary for every 
observer to ascertain for himself the magnifying power of his lenses, and he 
may construct little tables in the manner I have described. 

“In order to make an accurate microscopical drawing, the image of the 
object is carefully traced on paper with the aid of the glass-reflector, and 
afterwards finished by the aid of the eye alone. In order to obtain the size 
accurately, care must be taken that the distance between the reflector and 
the paper is the same as that between the former and the object-glass. The 
drawing having been finished, one of the scales made as above described may 
be gummed on in one corner of the paper. 

“Of Drawing Objects in the Microscope, from which it is intended to take 
Lithographs.—The lithographs illustrating the papers in the present number 
have been made by copying the image, with the aid of the reflector, on trans- 
fer-paper, with lithographic ink or chalk.* 

“The drawing on the transfer-paper being complete, is transferred to a 


finely grained lithographic stone and properly fixed; impressions may then 
be taken off.’ 


All the papers in this number have greater or less merit, 
and we can cordially recommend Dr. Beale’s ‘ Archives’ to 
the patronage of our medical readers. 


* “The best transfer-paper for this purpose is made of India paper. The 
ink and chalk can be purchased at any lithographer’s. Fluid lithographic 
ink answers very well, and was used in making the drawings.” 

t “The drawings have all been carefully copied from the objects them- 
selves on transfer-paper in my house, and then transferred to the stone. 
The transfers have been made and the impressions printed off by Messrs. 
Harrison and Sons, of St. Martin’s Lane, and it is only right that I should 
thank those gentlemen for the trouble and interest they have taken, and for 
the kindness which they and their workmen have always shown in carrying 


out this plan of producing the drawings, as well as other suggestions which . 
have been rade.” 


CARPENTER, ON ZOOLOGY. 117 


The Microscope: its History, Construction, and Application. 
By Jasez Hoee. Third Edition. London: Routledge. 


Wuewn Mr. Hogg’s work first appeared, we predicted for 
it a large sale, on account of its excellent illustrations and 
low price. He tells us, in his preface to this, the third 
edition, that two editions, of five thousand each, have been 
sold, thus fulfillimg our prophecy. We know, also, that other 
works have been equally successful, affording a gratifying 
proot of the extended interest taken in microscopic researches. 
In this third edition, Mr. Hogg has taken the opportunity 
of adding much new matter, and bringing up the information 
it contains to the time of publication. 


Zoology ; being a systematic account of the General Structure, 
Habits, Instincts, and Uses of the principal families of the 
Animal Kingdom. By W. B. Carpenter, M.D. Vol. I. 
A new Edition, edited by W. S. Datuas. London: 
Bohn. 


WE call attention to this new and cheap edition of Dr. 
Carpenter’s work on Zoology. It is now published in Mr. 
Bohn’s series of standard scientific works, and has been 
brought up to the present requirements of the science of 
zoology by the aid of Mr. Dallas, whose scientific labours as 
a zoologist are well known. 


118 


PROCEEDINGS OF SOCIETIES. 


Microscoricau Society, October 21st, 1857. 
Grorce Suapsort, Esq., President, in the chair. 


A paper was read by Dr. Donkin, “On the Marine Diato- 
mace of Northumberland, with a description of twenty new 
species. (‘Trans.,’ p. 12.) 

Another paper, by T. 8S. Ralph, Esq., “On a Mode of Iila- 
minating Objects,” was read. 


November 11th, 1857. 
Grorce SuHapzott, Esq., President, in the chair. 


H. W. Lobb, Esq.; Samuel Mason, Esq.; John May, 
Esq.; Thomas Spencer, Esq.; and G. Y. Sharpe, Esq., were 
balloted for, and duly elected members of the Society. 

A paper, by T. 8. Ralph, Esq., “On a Mode of Perforating 
Glass Slides for Mounting Objects, and on various methods 
of Mounting Objects in them,” was read. (‘Trans.,’ p. 34.) 

Mr. R. J. Farrants made the following remarks : 

‘“‘The author of the paper just read has noticed the want of 
a-medium in which moist specimens could be mounted and 
preserved, the requisite properties being that it should ‘ vis- 
cify, and be readily miscible with glycerme and with water. 
This want is, in part at least, supplied by the gelatine me- 
dium of Mr. H. Deane, the formula for which was given in 
the third volume of the ‘Transactions’ of this Society, but 
which the author seems to have overlooked. This medium is 
rendered fluid by heat, the necessity for which in many cases 
precludes its use. In its stead I have for some time used a 
mixture of gum and glycerine, which I find suitable im all 
cases where the gelatine medium is proper, while it may also 
be used for mounting some other delicate structures for 
which the gelatine would be unsuitable. Gum in solution 
was, some years ago, extensively tried as a medium for 
mounting microscopic objects; but its tendency to crack 
when dry (by which it frequently happened that the object 
immersed in it was spoiled) was found to be an imsuperable 
objection to its use, and it was, I believe, entirely super- 
seded by Canada balsam. Now the tendency of the gum 
to crack on drying, may be altogether prevented by the 


PROCKEDINGS OF SOCIETIES. 119 


addition of glycerine to the solution: the proportions I have 
used are equal parts of gum, distilled water, and glycerine ; 
to prevent the growth of minute alge or fungi in the 
mixture I have added a little arsenic. The following is 
the formula I would recommend: Boil together, in a Flo- 
rence flask or porcelain capsule, 3 grains of arsenious acid 
and 2 fluid ounces of distilled water ; when cold filter through 
paper. ‘Take of this arsenical solution 1 fluid ounce, of pure 
glycerine 1 fluid ounce, of pure gum acacia 1 ounce (Troy). 
The gum should be dissolved without heat; a fortnight or 
longer will be required for its complete solution: in the 
mean time the mixture should be occasionally stirred with 
a glass rod ; it will be well not»to shake the bottle so as to 
froth the mixture, for air introduced is retained with great 
tenacity, and many days elapse before it entirely disappears. 
If due care be taken in selecting pieces of gum transparent, 
bright, and free from impurities, the mixture will not need 
filtering ; if, however, foreign matters have accidentally 
gained admission, the best substance through which to strain 
the mixture is fine cambric, through which a considerable 
quantity of clean, cold water has been made to flow, so as to 
wash away any dust or loose fibres of the fabric which might 
find their way mto the mixture. This is an almost saturated 
solution of gum; it has nearly the consistence and appear- 
ance of fresh, pale Canada balsam, and is to be used in the 
same way, but without heat. The portion of the liquid 
which extends beyond the thin glass cover, soon dries (the 
water rapidly evaporating), the residue being a tough elastic 
compound of gum and glycerine, strongly adhering to the 
glass, and with no tendency to crack. The superfluity may 
be cut away with a knife, and any remaining smear be.re- 
moved by a piece of soft rag moistened with clean cold 
water. The specimen may be left in this state like an ordi- 
nary ‘ balsam-mounted’ object; or the edges of the thin 
glass cover may be coated with any of the cements commonly 
used for that purpose, or (which I prefer) a piece of tinfoil, 
with a hole of appropriate size, may be placed over the cover 
and be cemented to the slide with a solution of Canada balsam 
in ether. The most delicate structures are well shown and 
preserved in this medium—such as thin sections of recent 
vegetables, starch corpuscles, mycelium, and sporules of fungi; 
cells, vegetable or animal; the thm, delicate membrane of 
small hydatid cysts, &e. Pathological specimens, so difficult to 
keep unchanged for more than a short time, have been better 
preserved in this medium than in any other with which I am 
acquainted ; cancer cells, for example, have been kept unal- 


120 PROCEEDINGS OF SOCIETIES. 


tered in their optical characters for a period of two years : 
beyond this my experience does not extend. I imdeed have 
no reason for supposing that specimens which have remained 
so long unchanged should not continue well preserved ; fur- 
ther experience will, however, afford the surest means of 
determining the sufficiency of the medium as a preservative. 
Some recent and moist structures, animal and vegetable, 
admit of bemg mounted in Canada balsam without being 
previously dried ; the advantage of this is, that the parts of 
an object are not distorted, as must, to a greater or less ex- 
tent, always happen when a specimen is completely desic 
cated. The manner of proceeding is as follows: Take the 
specimen from the water or other liquid in which it has been 
prepared, let it drain a little, and then immerse it in rectified 
spirits of wine; after a short time (varying from one or two 
to ten or fifteen minutes, according to the size and thickness 
of the specimen), remove it from the alcohol, and, after 
draining, place it in methylic alcohol, otherwise known as 
pyroxilic spirit, pyro-acetic spirit, &c. After allowing it to 
remain a few minutes in this liquid, it may be removed, 
drained, and immersed in spirits of turpentine, on being 
taken from which, after a few minutes, it may be placed in 
balsam, and be proceeded with in the usual manner; the 
balsam ought to be sufficiently fluid not to need the employ- 
ment of heat. It is recommended to pass the specimen 
from common to methylic alcohol, and thence to spirits of 
turpentine, because the turpentine mixes more readily with 
the latter than with the former; observe, however, that 
the spirit referred to is TRuE methylic alcohol, or pyroxilic 
spirit, not what is commonly known as methylated spirit, which 
is common alcohol contaminated with wood-naphtha, &c. 
Injected preparations are well preserved and displayed in 
this way: there is no displacement or distortion of parts, and 
while the vessels are shown in their true position and rela- 
tions, the object is more securely and permanently preserved 
than if mounted in a cell with liquid in the ordinary manner ; 
for, notwithstanding the greatest care cells will leak, and 
there are I believe few collections which after a lapse of four 
or five years will not contain cells into which air has passed, 
and from which a corresponding quantity of the original 
liquid has escaped. It has been said that this way of 
mounting objects in Canada balsam is neither original nor 
new, and in order that merit may be given where, it is 
said, merit is justly due, reference has been made to some 
beautiful preparations of the nerves, &c., by Dr. Andrew 
Clark, put up in this way a year and a half or two years ago. 


PROCEEDINGS OF SOCIETIES. 121 


I reply that I do not claim any merit either for originality 
in proposing, or for priority in using this plan, which indeed 
is likely enough to have occurred to many persons who have 
been much occupied in preparing and mounting objects for 
the microscope; as, however, I thought it not unlikely that 
this method might be unknown to some persons present, and 
judged also that the place and the occasion were proper, I 
ventured to mention it. Perhaps I may be allowed to add 
that I have specimens of injections prepared and mounted in 
this way as long ago as 1850, and though at first I had 
recourse to this method but rarely, being uncertain about its 
permanence, | have now for several years mounted ‘ injec- 
tions’ almost exclusively in this way, either in cells or 
without them, as the thickness of the specimen required. I 
have also a pretty extensive series of sections of the roots, 
woods, and barks of the Materia Medica, prepared and 
mounted in this way, with the advantage of well-secured ob- 
jects, without falsification of the optical characters of the 
. structures.” 

Mr. Wenham said—“ Having had considerable expe- 
rience in working glass, for optical purposes, I may state, 
that I frequently make use of hard steel with turpentine for 
rapidly reducing to form pieces of glass chucked in the lathe. 
I take a three-square saw-file, and grind away one of the 
faces as it loses its keenness and becomes worn; this con- 
stantly leaves two sharp serrated edges, which are applied to 
the revolving piece of glass, ‘ overhand’ or in the way that 
a spoke-shave is used, supporting the file on the T rest, 
which is raised nearly level with the top of the work. 
I also employ turpentine for drilling glass. If the drill is 
made of the hardest cast steel, and hardened by quenching 
in dilute sulphuric acid, without being afterwards tempered, 
I can drill an eighth-inch hole through a plate of glass one 
inch thick in about one minute. The dmill should be 
sharpened on both sides, so as to cut either backwards or 
forwards, and is best worked by the Archimedean drill-stock. 
Most glass is somewhat softer than hardened steel, but if 
the attempt be made to drill glass dry, a very intense heat is 
generated on the cutting edge, which destroys the temper 
and softens a very minute superficial film of the steel, which 
is then rubbed away, leaving a round edge unsuitable for 
cutting. The turpentine does not act in any peculiar way 
upon the glass itself, but its extreme fluidity and penetrating 
quality enables it to bathe the end of the drill during its 
rapid rotation, and by thus keeping it cool its hardness is 
maintained. For glass-turning I prefer old turpentine, as 


128 PROCEEDINGS OF SOCIETIES. 


it does not evaporate quite so readily. There is another 
point that I may notice in the paper that has just been 
read. The author mentions that by cutting off the heads 
of flies and grasping one of them between the finger and 
thumb the proboscis with all its apparatus will be pro- 
truded in the symmetrical arrangement proper for mounting. 
I invariably make use of this method. Take the proboscis of 
the blowfly for example. The flies are best when very young, 
having been hatched in’ a dark box, otherwise their probosces 
will be opaque and more intractable than when they have not 
been hardened by exposure to air and light. Having cut off 
the heads, they should be macerated for some hours in water, 
then on grasping the head between the finger and thumb, the 
proboscis will become highly inflated (indeed if the pressure 
is too great it will burst), then nip it between two slips of 
glass, having a small elastic band around them, to spring 
them together, now cut off the head, and leave the proboscis 
under pressure until it is dry; it will then retain its form, 
which will be quite symmetrical, and may be finally mounted - 
in Canada balsam in the usual way.” 

After some remarks from Mr. Brooke the discussion closed. 

The final Report of the Committee “ On the best uniform 
method of attaching Object-Glasses to Microscopes,” was 
read. Resolved that it be received and adopted. (‘'Trans,’ p. 
39.) 

December 9th, 1857. 
Grorcr SHapsott, Esq., President, in the chair, 


Captain John ‘Peel, 14, Ulster Place ; Geoffrey Bevington, 
Esq., Wandsworth Common; J. J. Harding, Esq., 1, Barns- 
bury Park; J. W. Harker, Esq., 24, Upper Barnsbury Street, 
were balloted for, and duly elected members of the Society. 

A short paper by Mr. B. J. Nowell was read, ‘ On the 
Menai Straits as a locality for the Collection of Diatomacez.”’ 
The author adverts to the fact that the mud of which some 
portion of the shore is composed is particularly rich in Dia- 
tomacere, and states that the gathering is best pursued be- 
tween high and low water mark, the surface and the bottoms 
of the little pools being skimmed in the usual manner. The 
united proceeds of these skimmings are to be placed in a 
shallow vessel and exposed to the sun for some time and then 
re-skimmed. It is then recommended that the usual manipu- 
lations with hydrochloric and nitric acids, assisted by heat, 
should be performed, the “ result being a collection replete 
- with beautiful forms.” Some slides containing the forms 
collected in this way having been transmitted by the author 


PROCEEDINGS OF SOCIETIES. 123 


to the President, that gentleman furnished the meeting with 
the following list of species observed by- him on the in- 
spection (cursory) of a few slides, and from which the rich- 
ness of the locality may be judged of. 


List oF SPecrIEs oF DIATOMS NOTICED IN Mupb FROM THE MENAI STRAITS 


Coscinodiscus radiatus. Pleurosigma angulatum. 
4a minor. Fe decorum. 
ne excentricus. 3 litorale. 
Eupodiscus sculptus. 5) distortum. 
3 Sulous. a ? 1. sp. 
45 CVASSUS. Grammatophora marinu. 

2 ee radiatus. pS serpentind. 
Actinocyclus undulatus. Melosira maculata. 
Actinophenia splendens. Orthosira arenaria. 
Triceratium favus. Biddulphia rhombus, 

> elliptica. 95 aurita. 
ie amphisbenda. ES turgida. 


Pleurosigma balticum. 


“On a peculiar Larve Form resembling Pluteus,” by Dr. 
Cobbold. (‘Trans.,’ p. 50.) 
~ “Directions for Making Spherules of Calcareous Salts, with 
some Observations on Molecular Coalescence,” by G. Rainey, 
Esq. (‘ Trans.,’ p. 41.) 

A discussion followed the reading of this paper. 

Professor Quekett stated that he had observed crystalline 
spherules in the urme of the horse, in a specimen which had 
been kept for many years in the Museum of the Royal Col- 
lege of Surgeons. 

Dr. Carpenter thought Mr. Rainey’s observations very 
important ; but he believed that in shells there was a true 
cellular structure. 

Dr. Lankester said that Mr. Rainey’s observations were 
interesting in connection with those made by Mr. Sorby 
on the physical causes producing the Oolitic structure in 
rocks. 

Professor Busk referred to an oolitic deposit in the lake of 
Mexico, which was produced, not by physical causes or spheru- 
lation, but by the deposit of caleareous matter on the surface 
of the ova of an insect which lived in the lake. The ova, 
when recent, were eaten by the natives; but those which 
were not taken for this purpose became cemented into a true 
oolitic petrifaction. 


124 


ZOOPHYTOLOGY. 


For the interesting additions to the Zoophytological 
Fauna of Madeira, contained in the following list, we have been 
indebted to Mr. J. Yates Johnson, so well known as an 
assiduous cultivator of the natural history of that island, 
and more especially of its marine productions. It is needless 
to insist upon the importance of contributions from such a 
locality towards a more complete knowledge than we as yet 
possess of the geographical disposition of species; but the 
consideration simply of such a short list as the present 
suffices to indicate that, so far as its Zoophytology is con- 
cerned, Madeira forms a connecting link between the Medi- 
terranean, on the one hand, and with the Western and 
astern shores of Africa and of South America respectively, 
on the other ; connected with the latter, perhaps, through the 
intervention of the Gulf-weed. 

The number of species comprised in the collection is about 
twenty-four, of which twenty belong to the Polyzoa, and four 
to the class of Sertularian Hydrozoa. 


The Polyzoa are arranged in the following families, with the 
characters given in the ‘ B. M. Cat. ’ 


. Scrupariade. 

. Salicornariade. 

. Bicellariadee. 

. Membraniporide. 

. Celleporide. 
Selenariadee. 

. Idmoneade. 

. Crisiade. 


DIA or Rw TO 


Class. Potyzoa. 
1. Sub-order. CHErLostoMaTa. 


1, Fam. Scrurariap#, Gray. 
1. Gen. Hucratea, Lamx. 
Unicellaria, Blainville. 
1. #. Lafontii, Andouin, ‘ Expl.,’ p, 242; Savigny, ‘ Egypt,’ pl. xii, 
fig. 2. 
This beautiful and very remarkable species belongs to the 
Mediterranean Fauna, occurring on the coast of Syria. It 


ZOOPHYTOLOGY. 125 


probably deserves to be raised to the rank of a distinct 
generic type, in which case the name of Kucratea (Aud.) 
might be retained for it and the &. Cordiert of the same 
author. 


2. Fam. Saticornariap#, Busk (‘B. M. C.,’ p. 15). 


2. Gen. Nellia, Busk (‘ B. M. C.,’ p. 18). 
Ll! W. Johnsoni, nu. sp. Pl. XIX, fig. 2. 
Front of cell pyriform, pointed at bottom; margin raised, thick, smooth. 
Mouth semi-orbicular, lower lip straight. Ovicell (?). 
Hab. Madeira, Johnson. 


Two small fragments only occur of this apparently distinct 
form. The natural size is shown in the plate. 


3. Fam. Bicertariap#, Busk (‘B. M. C.,’ p. 41). 


3. Gen. Bugula, Oken. 
1. B. gracilis, n. sp. Pl. XIX, fig. 1. 
Cells biserial, elongated, of nearly uniform width throughout ; a short spine 


on each angle of the aperture. Aperture not extending below the middle of 
the cell. Avicularia capitate, blunt (?), of uniform size. 


Hab. Madeira, Johnson. 


Although, in the character of the cell, this species ap- 
proaches in some respects near to B. plumosa, and in the 
number of spines to B. turbinata (Alder), the comparative 
shortness of the aperture and, above all, the extremely dif- 
ferent habit, so far as that can be judged of from the small 
specimen seen by us, appear to afford sufficient grounds for 
‘its being regarded as distinct from either. . 


3. B. flabellata ? Thompson. 
a. var, biseriata s. Ditrupe. 


Although we have named the form as above, it will 
probably have to be regarded as a distinct species. Its 
habitat is very peculiar, and as in the very numerous 
specimens shown to us by Mr. Johnson, the most remark- 
able uniformity was exhibited, both in this respect, and in 
general size and habit, and no indication whatever existed of 
a nearer approach to the usual form of B. flabellata, this 
supposition is rendered the more probable. The Bugula 
always grows in a small tuft, about half an inch in height, 
and consisting of three to four narrow branches, close to the 
mouth of a species of Ditrupa (D. acuminata). It might on 
this account, perhaps, be denominated B. Ditrupe. A figure 
and fuller description of it will be given in a future number 
of the ‘ Journal.’ 


126 ZOOPHYTOLOGY. 


4. Fam. Mempranirorip®, Busk (‘B. M. C.,’ p. 55). | 
4. Gen. Membranipora, Blainville. 
1. M. tuberculata, Bose. Pl. XVIII, fig. 4. 


Cells oval; margin granular; aperture partially filled in all round by an 
irregular jagged calcareous expansion ; two to four blunt spines or tubercles 
above the cell, often united into a single bifid knob. 


Hab, Madeira, Johnson; Rio de Janeiro, M‘gillivray; Gulf-weed wbique; 
on fuel. * 


Flustra tuberculata, Bose, ‘ Vers.,’ 2d ed., t. iii, p. 143 (ex. syz.) 
Flustra membranacea, Esper, ‘ Flustra,’ pl. v. 


_ This very abundant and extensively spread species we had 
formerly confounded with M. membranacea (‘ B. M. Cat.,’ 
p- 56, pl. lxvin, fig. 2), with which, on superficial inspection, 
we regarded it as identical, until our attention was directed 
to it by Mr. Alder, who was inelined to consider it as dis- 
tinct from that well-known form. We are inclined to regard 
this opinion as correct. The way in which it covers the air- 
vesicles of Fucus natans with its. beautiful calcareous network, 
and spreads over the surface of other Fuci, closely resembling 
the habit of WM. membranacea, taken with the circumstance of 
each cell being crowned with two short tubercular spines, on 
a cursory glance naturally induced the supposition that the 
two forms were identical. They differ, however, in several 
important particulars. MM. tuberculata appears to be far more 
caleareous than M. membranacea, The front of the cell is 
not oblong and angular, as is usually the case in the other 
species. The margin in M. membranacea is thin and smooth, 
and the area is not encroached upon by a calcareous ex- 
pansion. The spines, also, as Mr. Alder points out, in M. 
membranacea are usually, in part at least, flexible or corneous 
(though this is not always the case), whilst in M. tuberculata 
they appear to be invariably calcareous, short, thick, and 
blunt; and in the older cells usually united, so as to form a 
transversely elongated tubercle, thicker and more elevated at 
the sides. The form appears to be confined to the South 
Atlantic, and it is very generally met with on the Gulf-weed. 
With respect to the appellation, it seems quite clear that this 
is the form intended by Bose under the name of Flustra 
tuberculata, and there is no reason, therefore, that his desig- 
nation should not be retained. LEsper’s plate (we have not 
been.able to refer to the text) is a very good representation 
of the species as it occurs on Fucus natans. 

Our figure gives a bad idea of the M. tuberculata, and a 
better will be given in a subsequent number. 


2. M. trichophora, n. sp. Pl. XVIII, fig. 2. 
Front of ecll oval, expanded below and contracted above ; margin smooth 


ZOOPHYTOLOGY. 127 


or very faintly granular; no calcareous expansion; one or two very long, 
slender, hair-like marginal spines on either side of the upper part of the 
cell. Ovicell small, immersed ? 


Hab. Madeira, Johnson (on shell). 


The only form with which this can be confounded is M. 
Flemingii, Busk (‘ B. M. Cat.,’ p. 58, pl. Ixi, fig. 2, and_ pl. 
Ixxxiv, figs. 4—6), but from which it is clearly distinguished 
by the characters above given, and especially by the absence 
of any calcareous expansion, and the extraordinary length and 
slenderness of the hair-like spines. 


3. M. , i. sp. 
A figure and description of this species will be given here- 
after. 
5. Gen. Lepralia, Johnson. 
l. LZ. distoma,n. sp. Pl. XVIII, fig. 1. 


Cells pyriform, attenuated below. Mouth semi-orbicular, with a straight 
lower lip, separated only by a narrow bar from an avicularium, the opening 
of which is nearly as large as the mouth, the two openings being encircled 
by a raised border common to both. A depressed space on the front of the 
cell, the bottom of which is perforated with six or seven pores. A row of 
distant pores around the border of the cell. 


Hab. Madeira (on fucus ?), Johnson. 


From the form of the small fragments in our possession 
they would seem to be growing all round the slender 
branches of a fucus, but the species may turn out to belong 
to the hgulate Eschare. 


2. L. vulgaris, Moll. Pl. XVIII, fig. 3. 


Cells oval, convex ; surface subgranular. Mouth semi-orbicular, lower lip 
straight, with a median notch. Three or four superior marginal spines. 
Ovicell small rounded. A slender vibraculum on each side of the cell about 
the middle. 


Hab. Madeira, Johnson ; Mediterranean, Moll. 
Eschara vulgaris, Moll., ‘ Eschara,’ p. 55, pl. iii, fig. 10. 
Escharina vulgaris, Lamarck, ‘H.n. d.s. V.,’ 2d ed., t. ii, p. 281 (ex. 
syn. L. Dutertret). 
Cellepora vulgaris, Lamx., ‘ Hist.,’ p. 94. 
From Moll’s account, and the name he has given to this 
species, it would seem to be very common in the Mediterra- 
nean. 


3. L. P n. sp. 

This species will be afterwards described and figured. 
4. L. , a. sp.? resembling Z. ventricosa. 

This species will be afterwards described and figured. 
5. L. sceletos, n. sp. 

This species will be afterwards described and figured. 


128 ZOOPHYTOLOGY. 


6. L. radiata, Moll. 


Cells sub-oval, marked in front with radiating lines of pores, in a circum- 
scribed, nearly circular, raised space, usually not occupying the entire front 
of the cell. Mouth semi-orbicular. Four to six marginal spines. Nume- 
rous long intercellular blunt avicularia scattered over the polyzoary. 


Hab. Madeira (on shell?), Johnson; Mediterranean, Moll; Zschara 
radiata, Moll, ‘ Eschara,’ p. 68, pl. iv, fig. 17. 


It does not seem quite clear whether this species should 
be referred to Lepralia or Eschara, inasmuch as in one, of 
the small specimens brought under our notice, it seemed as 
if the growth sometimes rose up in an independent frond 
from the surface upon which the rest of the polyzoary was 
spread. We have followed Moll, however, in regarding it, at 
any rate provisionally, as a Lepralia. He states that this very 
elegant species covers other zoophytes and shells with a sin- 
gle layer of cells. The cells, as he observes, are much crowded, 
and consequently not unfrequently deformed and irregular 
in their disposition. He describes the radiating line of 
puncta as constituted of granules, but they are clearly rows 
of minute pores. His description of the avicularia is very 
good. 


5. Fam. CeLtLerorip#, Busk (‘ B. M. C.,’ p. 85). 
6. Gen. Cellepora, O. Fabricius. 
1. C. Hassallii (?), Johnst. 
This name is only given provisionally, though it will pro- 
bably prove to be correctly applied. A figure and descrip- 
tion of the form will be given hereafter. 


2. C. ramulosa, Vinn. 


6. Fam. Spvenartap#, Busk (‘ B. M. C.,’ p. 97). 
7. Gen. Cupularia, Lamx. 
1. C. Lowei, Busk (‘B. M. C.,’ p. 99, pl exvi). 
2B Bs ,. sp.? 
3. C. sSpen 
Figures and descriptions of these two apparently new 
species of Cupularia will be given hereafter. 


2. Sub-order. CycLostomata. 
1. Fam. Ipmonrap#, Busk. 


1. Gen. Zdmonea, Lamx. 
1. I. Adlantica, H. Forbes. Pl. XVIII, fig. 5. 
Except, perhaps, in its comparatively greater size and 
more robust habit, this form does not appear to differ in any 
material respect from that which occurs in the Northern 


ZOOPHYTOLOGY. 129 


seas. (Vid. ‘ Annals Nat. Hist.,’ 2d ser., vol. xviil., p. 34, 
pl. i., fig. 6.) 


2. Fam. Cristapm. 


Two species of Crisia, one of which appears to correspond 
with C. dentata in a dwarf state, and the other to be as yet 
undescribed, will be figured and described in a subsequent 
number. 


HypDkRozoa. 


Fam. SERTULARIAD. 
1. Gen. Sertularia, Linn. 
1. S. disticha, Bose. 
Hab. Madeira (on fucus), Johnson. 
S. disticha, Bosc., ‘Vers,’ 2d ed., t. iii, p. 121, pl, xxi, fig. 2; La- 
marck, ‘ Hist. d. An. s. V.,’ p. 154. 
Dynamena disticha, Audouin, ‘Expl.’ I, p. 244; Savigny, ‘ Egypt,’ 
pl. xiv, fig. 2; Lamouroux, ‘ Hist. d. Cor. flex.,’ 
p- 181; Blainville, ‘ Act.,’ p. 484. 
Dynamena distans, Bose, op. cit., p. 121; Audouin, ‘ Expl.,’ p. 243 ; 
Savigny, ‘ Egypt,’ pl. xiv, fig. 1. 

There appears to be no sufficient reason, from anything 
which appears in the excellent figures of Savigny, why 
D. disticha and distans should be separated. They both 
occur on the Gulf-weed. 


2. S. polyzonias, Linn. (in part). (Ellis, ‘ Corallines,’ pl. ii, fig. B. ; 
S. Ellisiit, M. Edw. in Lamarck’s ‘ Hist. d. An. 
s. V.,’ 2d ed., £. ili, p. 142.) 

We are indebted to Mr. Alder for the distinction from 
S. polyzonias (Linn. et Auct.) of a species having only three 
denticles or angles on the mouth of the cell, in place of four 
which may almost always be distinguished in S. polyzonias. 
This species, under the name of S. tricuspidata, is described 
and figured in his Catalogue of Zooph. of: Northumb. and 
Durham’ (p. 21, pl. ui, figs. 1, 2). An additional character, 
however, might perhaps be appended to those there given 
as distinguishing S. tricuspidata from S. polyzonias, the 
absence, viz., of four denticles from the mouth of the ovicell, 
both male and female, which always exist in S. polyzonias. 

Besides this, however, there seems reason to believe, not- 
withstanding Dr. Johnston’s weighty authority on the other 
side, that M. Edwards was right in suggesting that S. 
polyzonias should be divided into two species, also distin- 
cuished by the presence and absence of the denticles at the 
mouth of the ovicell. In the form for which he proposes the 
name S. Ellisit, the ovicell is clearly represented by Ellis 


130 ZOOPHYTOLOGY. 


(fig. B,) as it is in nature, with four denticles, whilst in that 
marked a in the same plate, the ovicell is represented very 
like that of S. tricuspidata. In the ventricose form of the 
cells, however, Ellis’s fig. a differs so widely from Mr. Alder’s 
S. tricuspidata, that it cannot be referred to that species ; 
so that it is not improbable a third species, for which M. 
Edwards would retain the term 8S. polyzonias, may be in- 
cluded in the Linnean species. 

The differences in the mouth of the ovicell do not depend 
upon sex, for although,a considerable difference may be per- 
ceived between the small white male cell and the larger 
yellow female capsule, in S. polyzonias, the mouth has the 
same conformation in both. 


2. Gen. Cryptolaria, Busk (Micros. Journ., Vol. V, p. 173). 
1. C. exserta, un. sp. Pl. XIX, fig. 3. 


Mouth of cells exserted. Poljaion pinnate or bipinnate; branches 
straight, rigid. Ovicell 


Hab, vente Johnson. 

This appears to constitute a second species of the genus 
Cryptolaria, the other belonging to New Zealand, and in 
which the mouth of the cell is completely immersed. 


3. Plumularia. 
A new species, belonging to the P. pinnata-group, will be 
described subsequently. 


ORIGINAL COMMUNICATIONS. 


On STEPHANOSPHERA PLUVIALIS. Condensed from the Ger- 
man of Professors Coun and Wicuura, in ‘ Nova Acta,’ 
vol. xxvi, Part 1. By Freprerick Currey, Esq., M.A., 
F.L.S. 


Stephanosphera pluvialis was first observed by Cohn, in 
1850, near Hirschberg, and described in Siebold and Kolliker’s 
‘ Zeitschrift,’* vol.iv, part 1. It consists of a hyaline globe, 
containing eight green primordial cells, arranged in a circle 
in its equator. The globe rotates upon an axis perpendicular 
to the plane in which the primordial cells are arranged, and 
moves actively in space by the aid of cilia, two of which pro- 
ceed from each of the primordial cells, and pierce the hyaline 
envelope. 

The primordial cells divide first into two, then four, and 
lastly into eight portions ; these portions separate from each 
other in a tangential direction, thus forming a dise round 
which a cellular membrane is developed. Two cilia are pro- 
duced upon each segment, and thus eventually eight young 
Stephanospherze are formed, which eventually escape by 
fissure of the parent-globe. This process was observed to 
occupy about twelve hours. Dr. Cohn has also observed the 
division of each of the eight primordial cells into a great 
number of microgonidia, which swarm within the globe and 
escape from it. 

Under certain circumstances each of the eight cells secretes 
a cellular covering, and swims about in the interior of the 
globe in the form of free Chlamydomonas-like cells. Even- 
tually they escape, either by fissure of the globe or by its 
gradual dissolution, lose their cilia, form a thicker membrane, 
become motionless, and accumulate at the bottom of the 
vessel. If the vessel be then permitted to become thoroughly 
dry, and afterwards be again filled with water, motile Stepha- 
nospherz reappear, from which it seems probable that the 
green globes are the resting-spores of the plant. 

In the Hirschberg habitat the Stephanospherze occurred in 
company with Chlamydococcus pluvialis, the resting-cells of 
which are with difficulty, if at all, distinguishable from those 


* Translated in ‘ Annals of Nat. Hist.,’ vol. x, pp. 321, 401. 
VOL. VI. i 


182  CURREY, ON STEPHANOSPHERA PLUVIALIS. 


of Stephanosphera. In the county of Glatz, however, Cohn 
found another habitat where the Stephanosphera was pro- 
duced without Chlamydococcus, and accompanied only by 
the red Rotifer, Philodina roseola. 

About the same time Wichura found a dark red crust 
covering some depressions on the surface of the mica- 
schist rocks at Quickjock, in Lapland. Upon moistening this 
crust Stephanospherz were produced, mixed, however, with 
Chlamydococcus. 

Afterwards Cohn and Wichura joined in a series of obser- 
vations on the water from Heuscheuer (county Glatz), the 
results of which form the subject of their paper. 

This water was placed (at the end of August) m vessels 
of common glass, green glass, &c., so as to test the effect 
of light. Im the darker vessels the primordial cells re- 
mained delicate, small, and distant from one another, whilst 
in the transparent vessels they grew much larger; and as the 
hyaline enveloping membrane did not extend in proportion, 
the green cells eventually came in contact with one another, 
and became spindle-shaped, with protoplasmic elongations. 
(Ply TN, fis...) 

After eight days the specimens grown in the transparent 
and dark vessels respectively, differed so much from one 
another that they might have been taken for different 
species. 

The size of the resting-spores varies very much, and it 
seems probable that they grow considerably after attaining a 
state of rest. Their colour is deep green (occasionally 
yellowish or olive), and they have a nucleus, and frequently 
a nucleolus. 

When the water is permitted to evaporate gradually, the 
resting-cells become yellow, and afterwards orange or red, 
aud their contents have a more oily appearance. The authors 
found that if the water was not permitted to evaporate, the 
resting-spores, although continuing to live, did not become 
developed into Stephanosphzerz, but when fresh water was 
poured upon desiccated resting-spores twenty-four hours 
sufficed for the production of motile Stephanospheeree. — 

The followmg is the process of transformation from the 
state of rest into the motile form. 

The dried resting-spores take up the water, and their 
contents (hitherto somewhat misshapen) gradually fill up the 
cavity of the containing membrane, and become cloudy and. 
granular (fig. 2); the border becomes yellowish, and the red 
colouring matter is concentrated in the centre. The cells 
then begin to divide, and the successive forms assumed in 


CURREY, ON STEPHANOSPH HRA PLUVIALIS. 133 


this process will be better understood by reference to figs. 3, 
4, 5, 6, and 7, than by description. In passing from the 
state shown in fig. 3 to that shown im fig. 4, the outer mem- 
brane has gradually become invisible. Up to fig. 7 the pro- 
cess has occupied about two hours. The four daughter-cells 
(fig. 8) begin to quiver, and to endeavour to separate from 
one another. ‘Two cilia are now perceptible at the pointed 
extremity of each of the four cells (fig. 9), by the action of 
which the group begins to move as a whole, and in a laboured 
manner, in the water; ultimately, however, all trace of the 
enveloping membrane and of the glutinous connecting sub- 
stance disappears, and one by one the daughter-cells escape 
and become free. Figs. 10, 11, and 12 exhibit different 
forms of these free daughter-cells, which contain two, three, 
or several granules (amylon?) and sometimes also vacuoles. 
The sharp end is often prolonged into a colourless beak, as 
in fig. 12. At this period there is no proper cellulose mem- 
brane. At the moment of escaping their diameter never 
exceeds 0'010 m.m., but they soon enlarge and attain a 
diameter of 0:013 to 0°015 m.m. 

Their form and the length of the beak is variable, the 
latter being sometimes altogether wanting. In form and 
motion they resemble exactly the naked primordial cells, 
. which are produced by division from the resting-cells of 
Chlamydococcus pluvialis. The authors have never seen the 
resting-cells of Stephanosphera divide into more than four 
parts, but think it not improbable that division into a greater 
number (eight or possibly sixteen) sometimes occurs. 

The length of time which elapsed between the immersion 
of the dried resting-spores and the first appearance of the 
motile cells varied from nine to twenty-four hours. It was 
noticed that those resting-spores which did not produce 
zoospores within six days never did so afterwards, although 
they continued to live and were perfectly healthy. 

Zoospores, produced in the month of November, did not 
advance beyond the first stage. (Figs. 10, 11, and 12.) 
Others, however, produced in March, remained only a few 
hours in that condition, after which time a delicate membrane 
was formed round the body of the primordial cell; this mem- 
brane was at first closely attached to the primordial cell, but 
became gradually enlarged by absorption of water into a 
colourless enveloping vesicle (figs. 13 and 14), usually globular 
but sometimes oval, having two openings, through which the 
cilia penetrate. In this condition they attain a diameter of 
0-017—0:022 m.m., and are not distinguishable from encysted 
forms of Chlamydococcus pluvialis. Other zoospores, produced 


134 CURREY, ON STEPHANOSPHARA PLUVIALIS. 


on the Ist of April, 1857, attained a larger size, and the 
protoplasm of the primordial cell, instead of retaining its 
continuous outline, became elongated here and there into 
simple or forked mucilaginous rays, which were either colour- 
less or green from the presence of chlorophyll (fig. 15). 
These rays are probably produced by the protoplasm adhering 
at certain points to the surrounding membrane, and being 
carried outwards by its growth. The Chlamydococcus-like 
form only lasted a few hours: towards the evening the 
zoospores mostly began to divide. In the first place, the 
protoplasmic rays are drawn in, and the primordial cell be- 
comes round; it then elongates itself in the direction of an 
axis passing through the point of origin of the cilia, and by 
the process of division assumes the forms shown in figs. 16 
and 17. This state is usually attained by about nine o’clock 
in the evening, and about eleven o’clock a constriction com- 
mences in a plane at right angles to the former plane of 
division, and eventually the primordial cell is divided imto 
quadrants (fig. 18), each containmg a nucleus and a portion 
of the red substance. The two cilia, which have retained 
their activity, originate in the interspace between two 
quadrants (fig. 18). About midnight usually, but sometimes 
earlier, constriction recommences, and the form in fig. 19 is 
attained. This constriction proceeds towards the middle . 
point of the spheroid, by which the quadrants are bisected, 
and ultimately divided into eight wedge-shaped portions, 
whose contour lines, like the spokes of a wheel, meet in the 
middle. 

And now commences a further process of development, 
which forms the ground of the generic distinction between 
Stephanospheera and Chlamydococcus. For, whilst in Chla- 
mydococcus the individual portions of a primordial cell sepa- 
rate entirely from one another, each developing its own 
enveloping membrane, and ultimately escaping as a uni- 
cellular individual; in Stephanosphzera, on the other hand, 
the eight portions remain united as a family. The coloured 
contents of the individual portions become drawn back towards 
the periphery in a centrifugal direction, a colourless plasma 
remaining about the central point; this disappears at first in 
the centre; a cavity is formed in the middle of the dise, and 
as this enlarges the eight portions assume the form of a 
wreath, consisting of eight globular or ellipsoidal bodies in 
close contact (fig. 20), and usually not exactly in one plane, 
owing to the outer membrane not having expanded in pro- 
portion to the enlargement of the plasma. The original 
cilia continue active, causing the motion of the whole 


CURREY, ON STEPHANOSPH ERA PLUVIALIS. 135 


organism, until the eight portions are completely individual- 
ised, and then their motion ceases. But at this period each 
of the eight parts may be seen to be provided with two cilia, 
which are in motion so far as their limited space allows. 
(Compare fig. 21, which represents an instance in which the 
division has only extended to four portions.) The separate 
parts of the plasma now form eight independent but closely 
packed membraneless primordial cells. Shortly afterwards 
it is seen that a delicate membrane, common to them all, has 
been secreted beneath the mother-cell-membrane, round the 
disc formed by the primordial cells; this membrane at first 
lies in close contact with the latter cells, following the con- 
strictions of the disc, but afterwards becomes further and 
further removed as it swells and tends to assume a globular 
form (figs. 22, 23). By the motion of the cilia the mother- 
cell-membrane is gradually thrown off, and the young family 
escapes into the water (fig. 24). Its eight green primordial 
cells still enclose the last traces of the red substance, which 
gradually disappears, and instead of which are seen two 
granules (fig. 25); the primordial cells are in immediate con- 
tact at the sides, and are of an oval or globular shape; their 
common enveloping membrane is at first constricted at the 
border following the outline of the primordial cells; it even- 
tually becomes globular, although continuing for a long time 
much flattened at the poles, in the form of a disc-shaped 
spheroid (fig. 24). When the Chlamydococcus-like unicel- 
lular Stephanosphzera has commenced its division early in the 
evening, the division into eight is perfected during the night, 
and early in the morning the young family quits its cast-off 
mother-cell-membrane. 

In the course of the day the individual primordial cells, 
and their common enveloping membrane, grow until the latter 
attains a diameter of 0:°040—O0:048 m.m. During this growth 
the shape of the primordial cells is changed by the formation 
of various prolongations in the manner above described (fig. 
1); but in the course of the afternoon the primordial cells 
again become round, and during the evening division com- 
mences in them precisely similar to the process in the uni- 
cellular Stephanosphera; on the following morning we find 
eight young families, with the common enveloping membrane, 
which soon escape and go through the same process. It is 
calculated that in eight days, under favorable circumstances, 
16,777,216 families may be formed from one resting-cell of 
Stephanosphera. It is remarkable that the division of the 
primordial cells in Stephanosphera is confined to a certain 
time of day ; it begins towards evening, and is completed the 


136 NUNNELEY, ON THE CRYSTALLINE LENS. 


following morning. The observations made in Lapland, at a 
time when the daylight there lasted during the whole night, 
the beginning and end of the division were observed to take 
place at almost the same hours as in the observations made at 
Breslau in the spring, when the day and night were almost of 
equal length. Sometimes the division ceases after the forma- 
tion of only four primordial cells (fig. 21). On one occasion 
the authors observed a family with only three cells, one only 
of the two halves first formed having undergone a second 
division. In Lapland a family with sixteen cells was once 
observed. 

The authors then proceed to discuss the nature of the 
resting-cells in Stephanosphera and Chlamydococcus, and 
come to the conclusion that they are not spores; 7.e., that 
they are not of the same nature as the red cells of Gidogo- 
nium, Bulbochete, Draparnaldia, Chzetophora, Spheeroplea, 
Volvox, &c. 

They come to this conclusion upon two grounds: Ist, that 
the resting-cells in question continue to grow after becoming 
quiescent ; and, secondly, that it is probable (although not 
yet proved) that the resting-cells increase by self-division, 
thus producing new generations of resting-cells. These two 
characteristics the authors consider inconsistent with the 
idea of a spore. 

In conclusion the authors notice the formation of mi- 
erogonidia in Stephanosphzera, which takes place by the 
division of the primordial cells into numberless small por- 
tions. Fig. 26 shows a Stephanosphera, in which all the | 
eight primordial cells have formed microgonidia; the indi- 
vidual microgonidia (fig. 27 a, 6, c) become free by the dis- 
integration of these eight groups into their constituent 
portions. The authors think it not improbable that th 
microgonidia exercise an impregnative influence in spore- 
formation, but admit that there is no evidence to prove it. 


On the Form, Density, and Strucruret of the CRYSTALLINE 
Lens. By Tuomas Nunne ry, F.R.C.S.E., Lecturer on 
Surgery in the Leeds School of Medicine, Surgeon to the 
Leeds General Eye and Har Infirmary. 


Tue Lens, as its name implies, is the most important por- 
tion of the dioptical ocular apparatus. It is at the same time 
the most perfect of its kind in the world. It has hitherto 
(and probably will continue so to do,) defied the efforts of 


NUNNELEY, ON THE CRYSTALLINE LENS. 137 


human ingenuity to imitate. Hence, while its importance in 
health, the great changes which it undergoes in disease, and 
the skill and knowledge requisite for its treatment and 
removal, have always rendered it an object of great interest 
to the anatomist and surgeon—its perfect action in con- 
verging the rays of light to a focus upon the retina, so as 
practically, if not absolutely, to overcome the aberration of 
sphericity, has caused its form, structure, and density to be 
matters of the closest investigation and calculation by op- 
ticians and mathematicians. The difficulties of the inquiry 
have been at least equal to their importance, so that as much, 
if not more, controversy and difference of opinion have 
existed as to the structure of the crystalline lens, as of any 
part of the eye. 

As is well known, the lens is partially imbedded in the 
anterior surface of the vitreous humour, where it is held in 
situ by the elastic suspensory ligament. It lies immediately 
behind the iris at the juncture of the anterior with the middle 
third of the globe. In man, mammalia, birds, and reptiles it 
is a double convex lens, of which the posterior surface is con- 
siderably the more convex, particularly i the two former 
classes. To the exact proportions which the curves of the two 
surfaces bear to each other, opticians have necessarily at- 
tached great importance. Many experiments have been made, 
and far more numerous elaborate calculations entered upon 
for determing it. Such inquiries are perhaps of more 
interest and importance to the optician than to the anatomist 
and surgeon; and from the nature and structure of the lens, 
when made experimentally, are not susceptible of absolute 
accuracy ; for it is almost impossible to measure, with mathe- 
matical precision, the curves of a small, delicate, yielding 
substance, like the lens. Moreover, it is beyond doubt, that 
not only do the two surfaces differ somewhat in different im- 
dividuals, but they vary very much in the same person at 
different periods of life. There is a gradual flattenmg of the 
surfaces, with an increasing density of the substance of the 
lens, as age advances. In the new-born infant the lens is as 
soft as rather thin jelly ; in old age as firm as suet. In infancy 
the lens is comparatively convex to its form in the aged. 
Fig. 1 (plate) shows their varymg forms—a in infancy, 6 in 
the adult, ¢c inoldage. However, notwithstanding these diffi- 
culties and changes, much interest and importance is attached 
to the determining, with as much precision as the nature of the 
case admits of, the form of the curves and the density of the 
material forming the lens. So far as I am aware, Petit, in the 
earlier half of the last century, is the only person who has care- 

VOL. VI. M 


138 NUNNELLY, ON THE CRYSTALLINE LENS. 


fully and extensively experimentally investigated the first of 
these problems ; for though many persons have since then, and 
particularly Dr. Porterfield and Dr. Thomas Young, written 
elaborately on the subject, it would appear their investiga- 
tions have rather been theoretical and calculative, based upon 
Petit’s measurements, than upon original experiment, except 
perhaps Dr. Young; and from his statement I am unable to 
determine whether he exclusively depended upon Petit’s 
figures or not.* According to Petit the diameter of the lens 
is about four or four and a half lines, and its axis two lines. 
“The diameter of the sphere of which the anterior segment 
is a part being from six to twelve lines, but most commonly 
about seven and a quarter or eight lines; whereas the dia- 
meter of the sphere of which its posterior segment is a part 
is commonly only about five or six lines.’”+ According to 
the calculations of Dr. Young the radius of the anterior 
surface of the lens is ‘30, of the posterior surface *22 of an inch. 

The following table will show the result of my measure- 
ments of the lenses of different creatures. I give them only 
as approximations to accuracy; for though I have taken every 
care that I could exercise to ensure as much correctness as 
possible, as I before said, I believe it to be impossible to 
measure any single lens with absolute precision ; the result of 
the whole must be looked at, and this, I think, will not be 
far from the truth. One proof I think of the general cor- 
rectness of the measurements, is the curious fact shown by 
them, that the proportion of the curve of the posterior 
surface to the diameter of the lens, is far more uniform than 
that of the anterior surface. The radius of the posterior 
curve differs very little in any of the creatures from the half 
of the diameter of the lens, so that in fact the posterior 
surface of the lens is nearly, but not absolutely, a hemisphere, 
while the anterior is a segment of a much larger sphere, it 
being on this surface that the variations at different ages in 
the individual, and different creatures, take place much more 
than in the posterior surface of the lens—a point of no little 
importance to the ophthalmic surgeon. The table also shows, 
that as we descend from man to fish, there is a gradual in- 
crease in the convexity of the lens until in them it is a true 
sphere, and that this increase in the sphericity is not neces- 
sarily accompanied by an increase in the density of the lens, 
as a reference to the table of the specifie gravities of the lens 
will show. The measurements are given in parts of an English 
inch. 


* «Miscellaneous Works of Dr. Thomas Young.’ By Dr. Peacock. 
Vol. i, Nos. 1, 2. 
+ Porterfield’s ‘Treatise on the Hye,’ vol. i, p. 231. 


NUNNELEY, ON THE CRYSTALLINE LENS. 


HUMAN CRYSTALLINE LENS. 


1. Large-sized adult male, one eye. : 

2,3. Adult male (et. 25), died after accident, 
both eyes exactly alike 

4,5. Adult female (zt. 40), died from heart dis- 
ae and albuminuria, both ones — 
alike 

6. Adult male (eet. about 50), one eye 

7. Male (et. 65), died from softening of brain, 


one eye . 
8. Small female, one eye ‘ 
Average diameter of eight eyes . 3500 
Average axis of eight eyes : "2000 
Average radius of posterior curve of 
lens of five eyes "1906 
Average radius of anterior curve of 
lens of five eyes . : 2551 


Six months’ feetus 
Nos. 4 and 5 were immersed for a few minutes 
in water at 160° F., the measurements 
were altered to— 

In No. 4 

No. 5 


MONKEY. 


1. Probably Jens somewhat too convex from 
being a short time in dilute spirit 


2. Ditto ditto 
PIG. 
1. Large, more than twelve months old 
9. Smaller, about four months old 
3. Of small breed 
4, Ditto B : 
Average diameter of lens : "4700 
Average axis of lens . : "3500 
CAT. 
Adult male cat just killed, both eyes exactly 
alike : : : 
BULLOCK. 
le é 
2. 
3. 
4. 
5. 
G 
(fe ; : 
Average diameter of lens : Tih 
Average axis of lens . 4.914 
Average radius of posterior curve e of 
lens. 3.483 


Average radius of anterior curve of 
lens). : é 4350 


33 
36 
“36 
“36 


36 
“OL 


"25 


ro3) 


Dia- 
meter 


139 


Radius of|Radius of 
ani, Pomtrionantero 
21 |-1697 |:2101L 
“18 |°2022 | 2664 
20 |°1896 | 2664 
29 = 4 
| = = 
20 = po 
14/)/ — we 
*22 11614 | -2000 
22 |°1503 |°1806 
94); — | pes 
90; — eee 
4,4 — ae 
32 we 
82 |°2011 |:2128 
"a2 |-2001 |-2198 


“50 
“50 
“50 
“50 
.50 
AT 
“47 


ale 


"3483 
3483 


: «700-300-2417 |-2720 


bel eles 


"4350 
"4350 


140 NUNNELEY, ON THE CRYSTALLINE LENS. 


SHEEP. 
: Radius of|Radius of 
Die | ani (oa 

1. 57 |°40 |-2892 |-3338 
2. 57 1°40 |-2892 |-3338 
3. “57 1°40 |:2892 |:3338 
4. 57 |°40 |:2892 |:3338 
is 60 |°40 |°38075 |°3612 
6. p . |°58 |°40 |°2952 |-3498 

Ager. age diameter of lens Fi 5766 

Average axis of lens . *4000 

Average radius of posterior curve 2932 

Average radius of anterior curve 3398 

HARE AND RABBIT. 

J. Hare , : ‘ . 1°46 1°37 1°2809 |°9453 
9. Ditto : , ‘ . 1°46 1°37 1°2809 | °2453 
3. Ditto, very large : : . 150 |38 | — — 
4,, Rabbit, rather ‘small ‘ 4 . {43 1°32 1-2184 |°2350 
5. Ditto, ditto 7 » 1:42 1539 | QOS 2275 

Average diameter of lens i 4.540 

Average axis of lens . *3520 

Average radius of posterior curve 2231 

Average radius of anterior curve "2382 

BIRDS.—COMMON FOWL AND DUCK. 

1. Very large cock, both eyes alike . » [32 |°22 |°1634 |:1872 
2. Ditto, ditto : . {27 [21 |:1850 |-1539 
DE Smaller cock, ditto : . {28 }:18 | — a 
4. Hen, ditto F . 1°26 1:17 Wls4ab essa 
5. Duck, ditto 5 . |°32 1:24 — ane, 
6. Ditto, ditto 2 . {26 |°20 |°13804 |°1456 

Average diameter of lens x *3850 

Average axis of lens . : 2033 

Average radius of posterior curve 1408 

Average radius of anterior curve “1606 


(Twelve lenses measured.) 
The lens of No. 2 was immersed in water at 


160° F. : » 1°26 | 23 11813 | 1456 
REPTILES. 

Alligator, both eyes alike . - . | 48 Ec _— | — 
Small frog, ditto ; . . |°20 | 16 0509 0532 
FISH. 

Cod, large, both eyes . : . 1°58 1-58 Equal. 
Haddock, ditto : : » |[°53, 1-63 | ise 
Holibut, ‘eft eye ; ; . |°52 |°52 Ditto. 
Ditto, right eye . 1°60. 1°50 Ditto. 


In this fish the right eye, in all its measure- 
ments, was smaller than the left, and it is a 
curious fact, that though the right lens was 
smaller than the left, yet its specific gravity was 
somewhat greater. 


NUNNELEY; ON THE CRYSTALLINE LENS. 141 


The axis of the lens is a line drawn from the centre of its 
anterior surface to that of its posterior. This in the human 
adult measures from the *18 to ‘22 of aninch. The diameter 
is a line drawn across from one point of the margin to the 
opposite, so as to divide the junction of the two surfaces. It 
measures from *31] to ‘36 of an inch in every direction, so 
that the lens is circular in its outline. This it is commonly 
regarded as being, not only in man, but in all animals. I am 
not, however, quite certain that some, which have the 
pupillary aperture very much extended horizontally, have 
not the lens also slightly broader in the horizontal than in 
the vertical direction. I have thought the measurements in 
some instances have been so. The axis of the lens is supposed 
to eorrespond exactly with the centre of the pupil. Now, as 
this is in most persons somewhat, and in some considerably, 
inclined towards the nasal side of the eye, were it so the axis 
of the lens would not correspond with that of the eyeball, 
but lie to its inner side. It is, however, far more probable 
that the axes of the lens and of the eyeball exactly cor- 
respond. 

The lens consists of its proper structure and its containing 
capsule. These are of totally dissimilar tissues. 

It is curious to note the very exaggerated notions which 
formerly were entertained as to the great density of the crystal- 
ine lens. Thus Matrejean concluded, from some experiments 
he made, that it is heavier than sulphuric acid or aqua 
fortis. But Dr. Porterfield informs us that Dr. Robertson 
weighed five crystalline lumens of the oxen’s eye and three 
of the sheep’s, and found the mean of the oxen 1°1134, of the 
sheep 1:1033, and of the eight to be 1:1083, from which he 
presumes that of the human to be the same. Chevenix 
states the sp. gr. of the human lens to be 1:079; of the sheep 
1:180.* These experiments are too few in number to be relied 
upon. ‘To determine the density of the lens in various crea- 
tures I have taken the specific gravity of a great number. 
The following tables will perhaps be thought sufficiently 
extensive ,to enable a fair estimate to be arrived at; more 
especially as these figures are not like those in the former 
tables. They may be taken without hesitation as correct, 
there being no difficulty in taking the sp. gr. of the lens. It 
will be seen that Porterfield in his conjecture was not far 
wrong as to the human lens, and that the average weight of 
Dr. Robertson and mine, for bullock and sheep, wonder- 
fully correspond, considering the individual lenses do not 


* Simon’s ‘ Animal Chemistry,’ vol. ii, p. 419. 


142 NUNNELEY, ON THE CRYSTALLINE LENS. 


weigh alike, a fact which I was not aware of until after all 
my experiments had been made. The tables show that, 
while there is a general agreement in the sp. gr. of the lens 
in animals of the same genus, there is a perceptible individual 
difference, which age alone will not entirely account for. In 
some few instances I have found the curious fact, that the 
sp. gr. of the two lenses, from the same creature, are not 
identical,* and the still more interesting one, that in such 
cases the size of the denser lens has been somewhat less than 
that of the lighter. This was well marked in the holibut, 
Nos. 6 and 7. They also show that in true land-creatures 
the sp. gr. of the lens is less than it is in water-creatures— 
the density of the lens of the duck, for instance, is decidedly 
greater than that of the common fowl—while the difference 
in that of the fish and the bullock and pig is very marked. 
The first table also shows that the lens is the densest of all 
the ocular tissues—and particularly so in the fish—where, 
from the density of the element from which it receives the 
rays of light, we should @ priori expect to find it so. 


Specific gravity. 


Bullock, entire eye ‘ : . 10411 
Lens taken from the same eye a2 5 . 11046 
Pig, No. 1, entire eye : : . 10803 
Lens taken from the same pig’s eye 11060 
Pig, No. 2, eyeball, with portion of optic nerve ‘attached . 11-0710 
Same eyeball without any optic nerve : . 105238 
Portion of optic nerve alone. ; - 1:0578 
Haddock, entire eyeball : ; - 1:0324 
Lens taken from the same eye . ; 11684 


The lens itself is also heavier than its capsule. The sp. gr. 
of a pig’s lens, without capsule, was 1:1015 ; with the capsule, 
1:0985. The average sp. gr. of four sheep lenses, with cap- 
sule, was 1:1152; of two lenses, without capsule, 1°1584. 


HUMAN LENS. 


1. Young adult man . 5 ; : : 11304 
2. Ditto : ; : : : 11304 
3. Adult woman : é , : 1:0909 
4. Ditto, : > . . 10967 
4) 44484 

Average ; : 11121 


o 


. Lens removed with anterior part of eyeball for disease of 
cornea of more than two years’ standing, which resulted in 


* Can this account for the fact of the focus of the two eyes differing, as is 
certainly the case in some persons, there being no perceptible difference in 
the appearance of the two eyes. 


NUNNELEY, ON THE CRYSTALLINE LENS. 


143 


the first instance from granular disease of conjunctiva at 
the gold-diggings. The sight was quite gone, and the other 
eye painfully involved; the iris adhered to the opaque cor- 


nea, but the lens appeared to be perfectly natural. 
weight, however, was increased to 


Its 
} : 11960 


Coagulation by water at 160° F. mereases the density of the 


lens, thus— 


No. 1, so treated, weighed 11666 
2, ditto, ditto 11739 
CAT. PIG (38 lenses). 

Both lenses exactly alike . 11491 = ; : ; ae 
3. 10864 
BULLOCK (7 lenses). 3)3-2909 

fr 1-107] 
2. 11078 Average 10969 
3. 11114 | HARE AND RABBIT (5 lenses). 
4. 1:1046 | 1. Hare : . 11248 
5. 1J111 | 2. Ditto 11065 
6. TNOSF V3. WhO! 5 11234 
‘i 11079 | 4. Rabbit. 11232 
5. Ditto 11232 

7)7°7596 
5)5°6011 

Average 11085 
Average 11202 

: COMMON FOWL (5 lenses). 
PERE AG lenses): 1. Large cock Eis els | 
Li 1:1143 | 2. Ditto 11366 
2. 11178 | 3. Ditto 10975 
3. VeTLIL. |, 4... Ditto 1:0975 
4. TET76. ) 5.) Hen, 11250 
4) 44.608 5)5°5697 
Average 11152 Average 11189 
COMMON DUCK (4 lenses). 
5. Lens without capsule 11562 | 1. : : . 11600 
6. Ditto 11607 | 2. 11600 
3. ? 10952 
9)2°3169 | 4. ° eeFLOS? 
i" 4.) 4°5204 
oe — Average 11301 
REPTILES. 


I have weighed the lens of the alligator, turtle, chameleon, toad, and 
frog, but as the three former had been in spirit or Goadby’s solution, and, 
from the time of year, I could only procure one small frog and toad, I 
abstain at present from giving the figures, as I am doubtful of their absolute 
accuracy ; but they are sufficiently so as to leave little or no doubt that the 
specific gravity of the lens in these creatures is intermediate between mam- 


malia and fish. 


144 NUNNELEY, ON THE CRYSTALLINE LENS. 


FISH (7 lenses). 


1. Cod . : . Lotte 
2. Ditto : : . Lalye 
3. Haddock . ; oe bel toy 
4. Ditto ° , . 11684 
5. Ditto . 5 - Life 
6. Holibut , : , iise3 
7. Ditto . ‘ . 11645 
7y8°2817 

Average ; », d:188l 


In estimating the sp. gr. of the lens it 1s essential that the 
eye should be perfectly fresh. If the animal has been dead 
any length of time the size of the lens is increased, but its 
sp. gr. lessened. If it has been preserved in dilute spirit its 
sp. gr. is diminished, while it is increased if it has been kept 
in Goadby’s solution, which answers so well for many tissues. 
The action of water at and above 160° F. is very uncertain. 
In the hard lens of the fish it scarcely alters the sp. gr., but 
commonly that of the softer lenses of birds and mammalia is 
increased. I have therefore rejected all the calculations 
made from lens which were not fresh—they include the lion, 
several monkeys, many reptiles, many human, and other 
creatures. 

The same remark, as to the necessity of employing only 
the lens of animals very recently dead, holds good in taking 
the measurement of its curves. It soon becomes too convex 
by imbibition of fluid; when preserved in spirit it also swells 
out; if kept in Goadby’s solution it shrinks in size and be- 
comes too flat. 

Reagents act upon the lens almost as they do upon 
albumen, yet not entirely, for though by boiling the lens its 
outer portion at once becomes opaque, the inner does not, as 
is best seen in the solid lens of a large fish, the centre of 
which becomes like transparent horn, while the outer is like 
coagulated white of egg. 

The composition of the lens is given by Berzelius as— 


Water . j ‘ ; . 58:0 
Peculiar matter (protein compounds) . ¢ oor" 
Hydrochlorates, lactates, and alcoholic extracts . 2-4 
Phosphates and watery extracts : Bi tegen 
Insoluble membranous residue : i yee 

100°0 


Simon (‘ Animal Chemistry,’ vol. ii) says, besides albumen 
there is in the lens a peculiar substance resembling casein. 


NUNNELEY, ON THE CRYSTALLINE LENS. 145 


This he calls crystalline. He gives the composition of the 
lens. 
In the ox. In the horse. 


Water ‘ - : » 165°762 60-000 
Albumen : : , « ,28:290 25°531 
Crystalline , : : - 10°480 14-200 
1 eK Te f ss : . 0:045 0°142 
Extractive matter, with chloride of sodium and 

lactates . ; f - 0495 0:426 


That the lens consists of fibres arranged side by side, in 
concentric layers, superimposed upon each other, com- 
mencing at the axis and passing from one surface or pole to 
the other, has long been known, particularly through the 
labours of Leeuwenhock, Derham, and Dr. Young; and that 
the human lens has a tendency to split at first into three 
sections, and then again into smaller, ordinary decomposition 
or immersion in weak spirit, boiling water, and other coagu- 
lating agents, readily shows; but the exact nature and 
arrangement of these fibres were much debated and disputed 
until a recent date. We are indebted to Sir D. Brewster for 
the first accurate account of the microscopic anatomy of 
this body,* and though in all particulars his description may 
not be fully borne out, yet his investigations did much to 
reveal the wonderful complicity of the minute anatomy of 
the lens. 

In order to examine the lens microscopically it should be 
rendered opaque, and hardened by alcohol, chromic acid, or 
hot water. If boiled for any length of time the fibres be- 
come irregular. I find immersing the lens for three or four 
minutes in water at 160°, and then adding to the morsel on 
the object-glass a drop of very dilute chromic acid, to 
develope the structure well. Acetic acid renders the fibres 
beautifully transparent and clear, but does not harden them 
so much as chromic, and soon acts upon them destructively. 
Liq. potassz destroys them immediately, ammonia more 
slowly. 

The lens of a large fish, the cod or haddock for instance, 
or of the frog or toad, should be selected for first observa- 
tions, as the fibres are stronger and their markings coarser 
than they are in birds, mammalia, or man; and of these 
lenses the middle portion should be selected, as upon the 
outer surface or margin the fibrous character is not well 
developed, and near the axis the fibres are so attenuated and 
delicate that their serrations are not so distinct. In other 
respects, in all orders of animals, the fibres appear to be 


* ¢Phil. Trans., for 1833 and 1836. 


146 NUNNELEY, ON THE CRYSTALLINE LENS. 


essentially of the same character, flattened, ribbon-like’ 
filaments, arranged side by side, so as to make a continuous 
layer, and connected, or interlocked together at their sides 
by serrations, which pass mutually into each other, just as 
the cranial bones do at the coronal and sagittal sutures. 
These serrations are by no means usually so uniform in size 
or number as they have been figured by Sir D. Brewster,* 
and they appear to me to be produced much in the same way 
as those in the cranial bones are, by the development and 
pressure of the fibres laterally against each other, and to 
result from the granules, of which the fibres are ultimately 
made up, pressing into the interstices of each neighbouring 
fibre ; for they are most distinct in the fibres of the hardest 
lens, and the serrations are largest and boldest where the 
granules are the largest. They are better marked where the 
filiform character is best developed, as in the middle rather 
than at the axis or margin of the lens, and the serrations 
become particularly developed by those reagents, which have 
a corrugating effect upon the fibres, as chromic acid and 
sulphuric ether. 

The fibres pass from one surface of the lens to the other, 
but whether every individual fibre does so, as stated by 
Brewster, is, I think, very doubtful; indeed, it is scarcely 
possible that all those near to the axis should do so, and, I 
think, many may be seen towards either pole becoming so 
attenuated as to be lost in, and amalgamated with, neigh- 
bouring fibres, the serrated edges and individual character 
being entirely lost. Each fibre is considerably broader at its 
middle than at its ends, towards which it gradually tapers, so 
that the greater width of the diameter of the lens over that 
of the axis is rather caused by the increase laterally in the 
middle of the fibres than by an additional number of fibres at 
this part. The depth or thickness of the fibres does not vary 
like the width, it appears pretty uniform in all the layers; 
hence, while the outer fibres are broad and ribbon-lke, the 
inner are almost cylindrical when separated, and when seen 
closely packed together in a bundle they appear hexagonal. 
This has doubtless led some observers into the error of de- 
scribing them as hollow tubes. Leeuwenhock described the 
number of layers as 2000 in the lens of a cod, and Sir D. 
Brewster calculated the number of fibres in each layer of the 
lens of a cod at 2500, and of the serrations in each fibre as 


* If a lens (of the cod, for instance) be strongly coagulated and then 
well dried, and a layer of the fibres be seen, the serrations are more uniform 
and regular than if a single detached fibre be seen or they are in the recent 
state. 


NUNNELEY, ON THE CRYSTALLINE LENS. 147 


12,500, which is, however, by no means certain. He assumes 
that the breadth of all the fibres in each layer is uniform, 
that the breadth of the fibres throughout the whole of the 
layers is five times the thickness, and that the serrations 
uniformly equal the thickness of the fibre, all of which 
assumptions are incorrect, for, while the thickness is tolera- 
bly uniform throughout all the layers, the breadth of the 
fibres not only varies very much in the different layers, but 
the fibres in the same layer vary very considerably im their 
breadth, and the serrations are irregular in number and 
boldness ; some being scarcely perceptible, while others pass 
boldly and deeply, even bifurcating, into the adjoining fibre. 

In the haddock and the cod I found a fibre, taken from 
near the middle layer (equidistant from the margin and axis), 
to measure in breadth 3:5 of an inch, of which the ser- 
rations on each side measured z;355, or the two together 
ss09, Or just equal to the breadth of the solid part of the 
fibre. In this part of the lens I found 2700 fibres to the 
inch linear, while close to the axis there were 5500 to the 
inch; while at the extreme surface the fibres were so indis- 
tinct as hardly to be formed; where they were, they measured 
at least twice, or more, as much as in the middle layers. 
(PL V1, Fie. 3.) 

In the frog, from the middle layer of the lens, I found the 
fibres to be about ;j5, thick and 3,55 wide, but by no 
means uniform in size. The ribbon-shape of these is well 
shown in fig. 4, where two fibres are twisted over upon 
themselves. In the turtle and the alligator there is a 
great difference in the size of the fibres, the outer being very 
broad and flat as compared with those near the axis. (Fig. 5.) 

In the fowl the fibres of the outer layers are very wide, as 
much as 7755 of an inch, as compared with WES from near 
the axis, most of which are not more than ;;155 of an inch, 
but some are considerably broader. The smaller are eylin- 
drical or slightly hexagonal, from pressure against each 
other, while the larger are ribbon-shaped (fie. 65), Ani 
the al the serrations are very sight, and the granules 
composing the fibres are very minute. 

In rodents, as the rat, squirrel, Bere and rabbit, the fas 
measure at the oe of the lens sso, Im the middle 30009 
near the axis sp/95 of an inch; the first bemg deeply serrated, 
the latter very slightly so. 

In a lens taken from a sheep just Sed I found its fibres 
from outer EEGs to be oes z000 tO +345 wide; in the 
ae layer z7s5p Wide, z3'55 thick; at the axis ,75. wide, 
and sz!55 thick. In the ox the Sere vary as we proceed 


148 NUNNELEY, ON THE CRYSTALLINE LENS. 


from the circumference to the axis from 555 to ; of an 
inch wide; and, as in all mammalia, the serrations are 
small. Fig. 8, shows a transverse section of a bundle of 
fibres from near the middle of the lens, in which the hexago- 
nal form of the fibres is seen. 

In the cat the fibres do not differ materially from those of 
other mammalia, but are very easily rendered irregular the | 
edge (fig. 9). 

In man the fibres differ but little from those of other 
mammalia. They are shown in fig. 10. 

The fibres are very flexible when in a natural condition, 
but after coagulation very easily broken ; hence they are re- 
presented by Arnold as made up of short portions ; but they 
are certainly long filaments, most of them passing from one 
surface of the lens to the other. The broader surfaces of the 
fibres appear to merely he in close apposition, where the 
layers are superimposed upon each other, and to adhere as 
all soft moist membranes do when in close contact, or, at 
most, to be weakly connected by mucus ; hence the lens far 
more readily separates into concentric layers than do the 
fibres from each other laterally. 

Kolliker describes the fibres to be thin-walled tubes filled 
with a clear viscid albuminous fiuid. In this, I think, he is 
in error, for though I have in some instances examined 
lenses where the central cylindrical filaments appeared to be 
tubular (particularly in the rat), they have been few and 
some days after death; and though sometimes the edges of 
the larger flat fibres present a darker lme, almost like a 
double wall, this is never seen sideways, and is probably only 
the effect of the edge of the fibres upon the hight when not 
fully in focus; while in every instance, whether of mam- 
malia, birds, reptiles, or fish, where the lens has been examined 
immediately after death, the appearance has been so constant 
that I think there can scarcely be a doubt that the filaments 
are really solid fibres—uniformly clear, transparent, and ho- 
mogeneous at first; but by heat, reagents, or decomposition 
soon becoming granular, then separating into granules and 
disappearing. These granules are smaller in birds and mam- 
malia than in reptiles and fish. The whole substance of the 
lens is harder and more dense in the latter classes than in the 
former, particularly in the fish as compared with the bird. 
In the latter the lens is soft and jelly-like throughout; the 
central portion, though more dense than the outer, is not so 
in anything like the same degree as it is in fish, where not 
only is the whole lens more firm, but the central part is m 
many genera of almost stony hardness, bemg difficult to cut 


NUNNELEY, ON THE CRYSTALLINE LENS. 149 


with a knife; the difference in the density of the two ele- 
ments from which the rays of light pass in enterimg the eyes 
of fish and birds being doubtless the cause of this difference 
in the solidity of the lens in these creatures. 

The arrangement of these fibres to make up the entire lens 
is not less curious than the structure and connection of the 
individual fibres. 

Four principal types have been described by Sir David 
Brewster, to one of which, or its subdivisions, the lens of 
every aninial may be referred. 

Ist. The first is the most simple, in which a single pole 
passes through the axis of the lens to the opposite point, to 
which all the fibres converge like the meridians of a globe. 
Upon this plan is constructed the lens of all birds, of most 
fish, and of some reptiles—the frog, for instance. Sir D. 
Brewster names the frog as probably possessing the next 
form of lens, that with two septa; but I have found it dis- 
tinctly with one pole. 

2d. The second type is found, amongst mammalia, in the 
hare, rabbit, and porpoise only; in some reptiles, and in 
several fish, of which the genus Salmo affords a good illus- 
tration. In this arrangement there is a short straight lmne 
passing through the pole from which the fibres symmetrically 
diverge, and passing over the margin of the lens, reach a 
similar line on the opposite surface, but which line is placed 
at right angles to the first, so that every fibre in‘each layer 
except four have their different parts lying in different planes ; 
thus, instead of passing directly from one surface to the other, 
they proceed in a curved direction round the lens. Such a 
lens is said to have two septa at each pole. 

3d. The third type is that of all mammalia except those 
just named. In it there are three septa, diverging at angles 
of 120° from each po'e, the septa of the posterior surface 
bisecting the angles formed by the septa of the anterior sur- 
face, thus making with them angles of 60°. “There are 
three fibres having their origin in the anterior pole and ter- 
minating at the extremity of the posterior septa, and other 
three having their origin in the posterior pole and terminating 
in the extremities of the anterior septa, which have their 
parts all lying in one plane, while every other fibre of the 
lens forms a curye of contrary flexure in order to carry it to 
its proper termination in the opposite septum. Hence it 
follows, that with the exception of the six fibres originating 
in the poles, the parts of all the other fibres which constitute 
the margin or rim of the lens are not parallel to its axis.”* 

* Brewster, ‘ Phil. Trans.,’ 1836. 


150 NUNNELEY, ON THE CRYSTALLINE LENS. 


This form is readily seen in the lens of almost any adult 
animal by the three sections into which it spontaneously 
separates. I think I have observed the septa to be always 
more regularly and distinctly marked on the posterior than 
on the anterior surface, probably on account of its greater 
convexity. 

4th. The fourth type is when there are four septa placed 
at right angles to one another, and being inclined at the two 
surfaces at angles of 45° to each other ; were the lens trans- 
parent and the septa seen at the same time, they would 
appear like the eight radii of an octagon, inclined 45° to one 
another. Few animals possess this arrangement ; the whale, 
seal, and bear being all that Brewster has found it in. 
Leeuwenhock described the whale has possessing five septa. 
In other lenses of the same animals there are two, or even 
three, centres of divergence, when there will be six radiations 
of fibres. 

In the human lens the arrangement of the fibres is the 
most complicated of any, for while the type is the mammalian 
tripod, and is best seen in the foetus, in the adult the planes 
are more numerous, In consequence of the primary planes 
immediately branching into secondary, so that a very com- 
plicated curvature of fibres exists; the septa upon the two 
surfaces frequently not being equal, those of the posterior 
being more numerous than those of the anterior. In the 
anterior nine septa and radiations are often found, in the 
posterior surface twelve, which Arnold regards as the more 
common arrangement in man. This complicity, however, is 
only in the more superficial layers, for towards the axis the 
normal mammalian triseptal division is preserved. 

The general arrangement of the fibres of the lens in dif- 
ferent creatures is most easily seen by immersing it for a few 
minutes in water at 180° F., then allowing it to dry in a 
warm room. In two or three days it will be found to have 
split into different sections, according to the direction of its 
septa, while the fibres then form good microscopic objects 
and are easily preserved by simple mounting in glycerine, 
but if kept im water they soon swell, the edges become very 
irregular, the substance granular, and then breaks up. 

Of the reason for these varying planes, or why they should 
differ so much in different animals, we are in complete 
ignorance ; no plausible conjecture has been offered. It has 
been suggested they are for the purpose of enabling the 
curves of the two surfaces of the lens to be modified so as to 
adjust the eye to vision at different distances. It for long 
has been a favorite idea with some anatomists and opticians, 
particularly with the latter, that this power of the eye to 


NUNNELEY, ON THE CRYSTALLINE LENS. 151 


overcome the aberration of parallax, resides in the lens itself. 
It was this preconceived notion that led Sir E. Home, to 
describe the structureless suspensory ligament of the lens as 
muscular, and determined the celebrated Dr. Young to see 
true muscle in the serrated albuminous fibres of the lens 
itself, and Porterfield to assert the contractile property of 
the ciliary processes ; but that the complicated interlockings 
of millions of serrated fibres, arranged in planes of varying 
curvature and number, should conduce to easy and constant 
modifications in the form of the lens is not a very probable 
supposition. The contrary idea, that they are for the purpose 
of preserving under every circumstance an unchanging sur- 
face would seem the more plausible notion. 

The capsule of lens is a perfectly transparent structure, 
which, though apparently so dense, is very permeable, and, 
like most animal membranes, allows exosmose and endosmose 
very readily to go on. If placed in air the lens soon desic- 
cates ; if put in water the capsule in a short time becomes 
swollen and ultimately bursts from the fluid which passes 
through it; if then punctured, its elasticity forces the water 
in a jet through the aperture. Doubtless it is through its 
pores the lens receives nutriment, as it is non-vascular. In 
structure the capsule differs 7m toto from the lens; none of 
the agents which render the lens opaque affect in the least 
the transparency of the capsule, which it retains for long 
after death. It is highly elastic, and closely embraces the 
lens, whose form, I imagine, it tends most importantly to 
preserve by an equable pressure. It is hard, dense, and 
strong; yet it is readily torn, and is cut with a grating noise. 
Itis so elastic that when divided it at once curls up, and that 
always in a plane opposite to what it is laid down in. If 
injured in the living eye, by even a very small wound, it 
often forces the lens to escape into the aqueous chamber. In 
its physical and chemical characters it appears to be identical 
with the inner elastic layer of the cornea. It is quite struc- 
tureless, and like it has a single layer of epithelial cells upon 
its inner surface. Though when in a normal condition it 
long remains unchanged by either reagents or decomposition, 
very slight injury during life, as the least puncture, at once 
renders it opaque, its elasticity is then lost, and it frequently 
becomes a source of great annoyance to the surgeon by the 
persistency with which it will remain expanded across the 
pupil. 

The inner surface is lined throughout by a single layer of 
cells, similar to those found on the inner aspect of the cornea. 
The cells are very transparent, are nucleated, and polygonal 


152 NUNNELEY, ON THE CRYSTALLINE LENS. 


figs. 11 and 12), but this I think results from mutual 
pressure, for when detached and allowed to expand by 
immersion in water they become circular, or nearly so. 
These cells appear to form the connecting medium between 
the capsule and the lens itself. Were it not that similar cells 
are found in Petit’s canal, I should feel inclined to think they 
are not merely the means of nutrition to the lens, but that 
they are lens-fibres in process of development. Any wound, 
however small, in the capsule during life, almost invariably 
leads to opacity and absorption of the lens. The anterior por- 
tion of the capsule is considerably, three or four times, thicker 
than the posterior half of it. ‘This probably arises from the ex- 
pansion of the suspensory ligament over it; or, if we suppose 
the latter to be an extension from the capsule, from it passing 
off from the capsule, just anterior to the margin of the lens, 
to form the anterior wall of Petit’s canal, where it is striated, 
from the continuation of the folds, which are received be- 
tween the ciliary processes (zone of Zinn). At this point of 
the capsule, just anterior to the margin of the lens, there is a 
sudden thinning of it, and after turning over the edge of the 
lens, the posterior capsule, though in other respects identical 
with the anterior, is much thinner and weaker. 

In a few hours or days after death the capsule is found 
separated from the lens by one or two drops of interposed fiuid. 
This is the Aguor Morgagni, and until very lately has been 
considered as a normal condition of the living eye. This, 
however, it certainly is not, for if the lens of any creature be 
examined immediately after death no fluid whatever is found; 
indeed, we can hardly understand how the vitality of the lens 
could be maintained, or the lens be kept steadily in situ, which 
for the purpose of vision would appear to be absolutely neces- 
sary, were it surrounded by a bath of aqueous fluid, however 
small. The least pressure of the muscles of the eyeball would 
induce an oscillatory motion of the lens. The fluid is a post- 
mortem effect; it is derived from the breaking down of the 
epithehal cells, and by endosmose,from the aqueous and 
vitreous humours. 

In the adult neither vessels nor nerves can be traced in the 
lens or its capsule; they are therefore regarded as extra- 
vascular; but during foetal life, up to the period of birth, 
and even some little time aftérwards, both contain vessels ; 
indeed, the capsule is then covered with a beautiful network 
of blood-vessels, derived, principally, from the central artery 
of the retina, by means of a considerable branch, which 
passes directly through the vitreous humour to the centre of 
the posterior capsule, where it minutely subdivides, the 


BRIGHTWELL, ON TRICERATIUM, ETC. 153 


vessels forming a very free inosculation with each other. As 
they approach the edge of the lens, which at this period does 
not fully reach the margin of the capsule, and is somewhat 
irregular at its cireumference, they have a tendency to run in 
pairs, and pass directly straight over the edge on to the 
anterior surface of the capsule, where they again spread out 
and form a stellate network ; but at the period of birth not 
so free as upon the posterior capsule; here they imosculate 
with other branches derived from the ciliary processes and 
iris, which at this period of life is in contact with the lens, 


FurtHER Opservations on the Genera Tricreratium and 
Cuatocreros. By T. Bricurwent, F.L.S. 


My former papers on these Genera have been chiefly 
confined to the description of species, and are necessarily 
imperfect, and to that extent unsatisfactory, in consequence 
of the difficulty of obtaining specimens in a living state. 
The species being all marine, very few opportunities occur of 
seeing them alive, and it is doubtful whether any one of 
them has been seen in a state of conjugation. If, as one of 
our highest authorities (the late lamented author of the 
‘Synopsis of the British Diatomacez’) says, “neither size 
nor outline can be wholly relied on, and striation is the best 
guide for specific character and, when this fails, the arrange- 
ment of the endochrome, or the habitat of the living 
frustule,” it is obvious how few of the described species can 
have been sufficiently known to warrant us in deeming them 
finally established, and how important is every step towards 
attaining a knowledge of the living diatom, and especially of 
its modes of increase. 

The recent discovery that the Diatomacez abound in most, 
if not all, the Tunicata, and even in animals so small as the 
Noctiluez, and that they are often found in those situations 
in a living state, promises to add greatly to our knowledge 
of the marine species. It was from sources of this kind that 
I derived materials for my paper on the Rhizosolenia, and it 
is from gatherings made from Noctilucee, and the stomachs 
of Sulpe, that materials have been obtained, which will, I 
trust, enable us to advance a step further in our knowledge 
of the genera mentioned at the head of this paper. 

VOL. VI. N 


154 BRIGHTWELL, ON 


I have already (vol. v, p. 191) explamed the origin 
of the pseudo-nodule in Triceratium undulatum, and shown 
that it is only the stump of a long cylindrical horn 
proceeding from the centre of the triangular end of the 
frustule, and further investigation has resulted in the dis- 
covery that this and another species, about to be described, 
and which we propose to name Triceratium malleus, are m 
their living and perfect state, filamentous. 

Triceratium undulatum has also presented itself under an 
aspect different, I believe, from any hitherto observed among 
the Diatomacee, and the character of which cannot at 
present be satisfactorily determined. In this state the frustules 
are placed one at each end of a mucous envelope, and are 
separated from each other by the exact length of the horn 
before described, and which proceeds from the inner end of 
each frustule. The frustules themselves are surrounded by 
siliceous bands united together lengthwise, having at each end 
a thick fringe or comb of short bristles or setze. A horn also 
proceeds from the external end of each frustule of equal 
length with that from the internal, the whole presenting a 
very abnormal and puzzling appearance. Further investiga- 
tion may, and I think probably will, show that it is one of 
what P. Smith terms “ the phenomena attending the forma- 
tion of the reproductive body” in this genus, and which are 
at present so imperfectly understood. In the state above 
described, the frustules not unfrequently present on an end 
view, a four-sided form, either square, or with the sides 
deeply indented, confirming what we have before stated as to 
varieties of this kind in several other species. 

In the filamentous state these appearances are consider- 
ably modified, the bands of silex beg more absorbed into 
each other, the horns shorter, and the combs or fringes of 
bristles or sete not apparent. In this state the sutural 
division seems effected in the normal mode, resembling 
somewhat, in the individual frustules, that of Biddulphia 
Bailey. The end view of the frustules generally presents 
the appearance of a triangular valve of silex imbedded 
in a softer siliceous cushion, the sides of the valve having 
each three undulations or indentations, evidently produced 
by the bands before mentioned; but variations of this_ 
structure are not uncommon, and there is one variety in 
which all the sides of the valve are perfectly straight. 

The other filamentous species, called by us Triceratium 
malleus from its resemblance to Malleus vulgaris, is larger 
than Triceratium undulatum, is without horns, and has no 
bands of silex surrounding the valves as in that species. On 


TRICERATIUM AND CHATOCEROS. 155 


an end view, the frustules are trilobed, the sides of the 
lobes are irregularly indented, and the valve exhibits the 
appearance of being composed of a series of thin layers of 
silex. In the filamentous state, the frustules are narrower 
than those of Triceratium undulatum ; and there is an ellip- 
tical opening between them on each side. 

Triceratium radiatum and Tr. Marylandicum (described by 
me, ‘Quart. Journ. Microsc. Soc.,’ vol. iv), present in 
the centre of the triangular end the appearance of a pseudo- 
nodule, and are probably filamentous, and of the same habit 
_as the two species already described. These species form a 
section or sub-genus. 


TRICERATIUM. 


§ Filamentous. 


—_ 


. T. undulatum.  Frustules with a horn running from the 
eentre of each end. 

T. malleus, n. sp. Valves three-lobed; the lobes of 
unequal length. 

T. radiatuin ? 

. LT. Marylandicum ? 


ee 


op 


CHA&TOCEROS. 


By the kindness of Dr. Wallich, I have been favoured with 
perfect specimens of the species of Chztoceros named by me 
Ch. Peruvianum (see vol. 11. p. 5), and which I had before 
only seen in fragments detected in guano from the Chinca 
Islands. Dr. Wallich’s specimens were taken from the sto- 
machs of Salpz found in the Indian Ocean, and they afford 
the only opportunity hitherto presenting itself of studying 
any species of this genus in a perfect state. 

The body, if 1 may so call it, of Ch. Peruvianum is com- 
posed of two segments which are not symmetrical, the anterior 
segment being (as described in the former paper) semicircular 
at the end, and furnished with two horns, which take their 
origin from two stout shoulders bending towards each other, 
leaving a hollow space between them, and then recurve at a 
right angle, and run tapering out to a very great length. 
This anterior section may properly be called the head, the 
other or posterior section being truncate, and terminating 
also in two long horns proceeding from the inner part of the 
segment. All four horns are of equal length, stoutly sili- 
ceous, spinous, and tapering. 


156 


On a Simpite Metuopn of applying the Compounp MicroscoPE 
to the Urrer or Lateran Surraces of Aquaria. By 
Perer Reprern, M.D., London University, and King’s 
College, Aberdeen. 


(Read at the Dublin Meeting of the British Association, in August, 1857.) 


Iv is important and convenient to have some simple 
method of examining objects in Aquaria with the compound 
microscope without disturbing them from day to day. The 
plan adopted by Mr. Warrington, and described in the 
‘Microscopical Journal,’ admits of the instrument being 
adapted to a limited surface with facility; but it is often 
desirable to be able to apply it to any part of a surface 
measuring two feet or more in extent. This end is gained 
by the arrangement described below. 

The woodcut shows the instrument in the position requisite 


( 


for examining the contents of a bowl standing on the table, 
or objects near the upper suriace of the fluid of an aquarium. 
a is a heavy cast-iron foot, seven inches in diameter, into 
which a vertical stem, 6, made of ordinary one-inch brass 
tubing, two feet long, is firmly screwed or soldered. c is a 


REDFERN, ON AQUARIA. esi 


narrow ring sliding easily on the vertical stem, and composed 
of two short sections of tube, one within the other. The 
inner piece is cut entirely through at the spot d; and at the 
opposite side, e, it is soldered to the outer one. Through the 
outer of these pieces the screw, f, works upon the inner one, 
tightening it and fixing the ring, c, at any height upon the 
vertical stem. 


g is a piece of tube three inches long, and split at the ends 
so as to slide and rotate easily on the vertical stem, 4, on 
which it can be supported at any height by the ring, c, which 
is below and unconnected with it. # is another piece of 
the same tube as g, placed at right angles across it, and 
rotating upon it. The joint between g and / is the only 
part of the apparatus which requires a brass casting to be 
made specially for it; all the other parts should be made of ~ 
such materials as are used for gas fittings. It consists of a 
thick circular dise of brass, an inch and a half in diameter, 
soldered to the tube, g, on one surface, and accurately turned 
in a lathe on its edge and the other surface, so that it may 
fit very tightly imto a cap turned like itself, but soldered to 
the tube, 2. These two parts fit each other like two of a 
series of nested apothecaries’ weights. Between them a 
leather washer is placed im a turned groove, and they are 
then screwed firmly together by a large screw inserted and 
turned through the hole, 7, cut in the front of the tube, h. 
I found that however tightly this screw might be turned, 
the joint, in which there is an exceedingly smooth motion, 
was too loose, and I therefore got the pinching screw, 4, 


158 REDFERN, ON AQUARIA. 


adapted to tighten it by a contrivance similar to that in the 
case of the rmg, c. A piece of the rim of the cap was cut 
out to the extent of five-eighths of an inch at /, and a thinner 
piece of brass, soldered only at one edge, was substituted for 
it. A ring of thin brass, n, having a projecting piece, 9, 
fixed to it by hard solder, was then applied and soldered 
around the rim, with its projection, 0, over the space, /, from 
which the edge of the cap had been removed. The screw, 
k, working through 0, presses the thin plate of brass, m, upon 
the edge of the brass disc, and without injuring the smooth- 
ness of its surface, tightens the joint to any required extent. 
p is a lever or arm of one-inch brass tube, twenty inches 
long, sliding through the tube, A, and rotating within it. One 
end of this lever is left open to receive a cylindrical piece of 
lead, which is sometimes useful to balance the lever when 
used with its arms of very unequal length; the other end is 
closed by the cup of a large ball-and-socket joint soldered 
into it. Loosening of this joint is prevented by the pinching 
screw, 7”. To the ball is attached a short arm, carrying the 
piece of tube, s, three inches long, sawn through lengthwise 
at the part most distant from the ball, and cut away as re- 
presented on the figure, so as to hold the tube of the body 
of the microscope loosely enough to allow of easy sliding and 
rotation for focal adjustment. I have the stem attached to 
ball made of two pieces screwed together, so that I can sub- 
stitute a cell holding a single lens or a doublet, to be used as 
a simple microscope, for the split-tube carrying the body of 
the compound instrument. To diminish the weight of the 
body of the compound microscope, I make it of paper pasted 
to form a thick tube, which is lined with black velvet. An 
adapter, carrying the lenses, slides into it tightly at one end 
and the eye-piece into the other. 

When in use, the most favorable position for the transverse 
arm, p, is near that represented in the woodcut, where it 
forms a lever with arms of unequal length. After coarse 
adjustment, by sliding the body of the microscope through 
the split tube, s, a very convenient fine adjustment is made by 
acting on the long arm of the lever. 

It will easily be understood that a considerable range of 
movement of the body of the microscope is allowed by the 
ball-and-socket jomt—by the movements forwards and back- 
wards, and of elevation and depression of the arm or lever, 
p, without shifting the place of the foot, a; whilst by chang- 
ing the position of the foot, and that of the ring, c, on the 
vertical stem, the whole of a surface not higher than two 
feet may be examined with readiness. When the transverse 


WALKER-ARNOTT, ON ARACHNOIDISCUS. 159 


arm has been carried up to the highest point of the vertical 
stem, and the body of the microscope placed vertically, it 
may be used on the surface of the fluid of an aquarium 
standing two feet high; the upward and downward move- 
ments of the transverse arm being then used for fine adjust- 
ment. 

This arrangement was made for me by Messrs. Farquhar 
and Gill, plumbers and gas-fitters, of this city, for less than 
thirty shillmgs ; but it must be borne in mind, that for cheap- 
ness it is essential that selected pieces of ordinary brass 
tubing be made use of, that the vertical stem and the trans- 
verse arm be pieces of the same tube, and the pieces, g and 
h, parts of another tube; also, that the ball-and-socket joint 
be the one ordinarily used by gas-fitters. Many of the de- 
tails of the arrangement, especially those connected with the 
various pinching screws, may appear tedious in description, 
but it will be found that these are poimts of great conse- 
quence for securing comfort and facility in making any obser- 
vation, and therefore I have described them at length. The 
application of a good rack-and-pinion for the movement of 
the body of the microscope would be a valuable addition, but 
it would increase the expense considerably. 


On AracuNoipiscus. By G. Warxer-Arnort, LL.D. 


Before having a complete knowledge of the natural history 
of Diatoms, it is necessary that we know—lst, where, when, 
and by whom any object was first observed and brought 
under the notice of naturalists, whether by name, descrip- 
tion, or a figure: 2d, where, when, and by whom it was first 
correctly named and defined by a precise differential (generic 
or specific) character, the latter of these alone giving a 
claim of priority. 

It is not twenty years since the genus Arachnoidiscus was 
known. Short as that period is, I have not been able to trace 
its history with satisfaction. I shall, however, indicate here 
the information I have obtained, and hope that those connected 
with its discovery and description will complete the sketch 
before it be too late: already one (Dr. Bailey) has been 
removed. 

It is generally said, and I believe with justice, that 


160 WALKER-ARNOTT, ON ARACHNOIDISCUS. 


Mr. Topping, and others in London, first observed these 
disks in Ichaboe guano. This guano was discovered in 1843, 
and was nearly all removed in the course of 1844.* Although 
guano was long known on the west coast of South America, 
I do not find that it was noticed for its diatoms until after 
that of Ichaboe was examined. 

Ehrenberg describes this genus under the name of Hemi- 
ptychus ornatus: when and where that name was given I have 
not traced, but believe it is in the ‘ Berl. Acad. Trans.’ for 
1848 or 1849. The description given in Pritchard’s ‘ Infus.,’ 
2d. ed., p. 382, shows that it is the form with transverse 
cost, and it is said to have occurred in “ Patagonian 
guano.” But here let me state that there is great difficulty 
in tracing the origin of guanos, not only from their being 
adulterated or mixed by the guano merchants, but by the 
preparers of objects for the microscope mixing what they got 
from different ships, under the impression that they were 
brought from the same place. Thus, some years ago, I pur- 
chased a slide of Diatoms from guano understood to be from 
Africa (Ichaboe); this contains the usual blue dises of that 
guano, but besides these is a valve (broken by pressing down 
the cover) of Hupodiscus (Aulacodiscus) formosus,+ which is 
peculiar to Bolivian guano. Here some guano from Arica had 
been mixed with that from Africa, the similarity of name pro- 
bably leading to the supposition that the two samples had come 
from the same locality. In Ehrenberg’s ‘ Mikrog.,’ tab. 35, 
he gives a representation of “ Peruvian” guano. In the 
description of the plate, however, it is stated to be from 
Arica, which is in Bolivia or Upper Peru, not in Peru as now 
limited. In the same work he exhibits the diatoms of two 
samples of guano from Saldanha Bay. The sample A. ap- 
pears correctly designed; but in B. all the species noticed 
(Endyctia oceanica, &c.) are so copious in Peruvian guano 
(called also Callao or Chinca), that I have no hesitation in 
saying that Ehrenberg must have misplaced the labels of the 
samples. 

I therefore doubt if the Hemiptychus ornatus was derived 
from Patagonian guano; but as the same form does occur in 
Californian guano, I dare not say that Ehrenberg’s was not 
from South America. 


* Whrenberg’s earliest notice of guano diatoms was in 1844, and his 
sample appears to have been obtained from London, and probably was 
derived from Ichaboe. 

+ Lu. (A.) formosus cupulis quatuor submarginalibus oblique mammeefor- 
mibus apice papillo instructis, granulis in 1-1000 parte septem (sive in 
1-100” parte sex) subaqualibus. — 


WALKER-ARNOTT, ON ARACHNOIDISCUS. 161 


In Smith’s ‘Synopsis of British Diatomacezx,’ p. 25, the 
genus Arachnoidiscus is said to have been proposed by Bailey. 
But I have before me the following extract of a letter from 
Dr. Bailey, of date July 27th, 1853 :—“I see that Smith, in 
his ‘ Brit. Diat.,’ gives me as the founder of the genus. This 
is not correct, but the species is mine, and it is very different 
from the A. Japonicus with which Smith confounds it.” The 
founder of the genus was Mr. H. Deane, of Clapham, and it 
was first noticed in a paper read by him before the Micro- 
scopical Society on 17th March, 1847. This paper was not 
published, and although it contained a general description of 
the disk, no distinguishing character was given. Mr. Shad- 
bolt, on 14th November, 1849, read a paper “On the Struc- 
ture of the Siliceous Lorica of the genus Arachnoidiscus,”’ 
and confirmed the generic appellation. In Pritchard’s ‘ In- 
fusoria,’ 2d. ed. (1852), the generic character will be found, 
and there also the name is correctly ascribed to Mr. Deane. 
In the ‘ Micrographical Dictionary’ it is said that Ehrenberg 
had now withdrawn the name Hemiptychus, as there was 
already a Hemipticha, a genus of Hemipterous insects. 

I now come to the species. In Pritchard’s ‘ Infusoria,’ 
page 700, the species there figured is called A. Japonicus of 
Shadbolt. Now Shadbolt’s specimens (figured im the ‘ Micr. 
Soc. Trans.,’ 11.) were from South Africa, and (if there be 
really more than one species) are not the same as the Japan 
form, and consequently not entitled to that name. Then 
again Bailey, as already said, gave the name of A. Ehren- 
bergi to a species from California (Puget Sound), which he 
supposed to be quite distinct from ‘A. Japonicus.”’ I cannot 
find that Bailey ever published this species; but Smith, in 
his ‘ Brit. Diat.,’ adopted it on the authority of De Brébisson, 
quoting A. Japonicus of Pritchard as a synonym. It 1s not 
very clear to me which Dr. Bailey meant. I have examined 
a slide prepared in 1853 from the Puget Sound form (got off 
an alga), and find it identical with the Japan one, but not 
with what is figured by Shadbolt or Pritchard; and another 
prepared by the late Professor Smith, and marked by him as 
obtained by Professor Bailey from California, and sent on 
22d October, 1856: but this is the African form figured by 
Shadbolt ; so that, if there be no mistake on the part of Dr. 
Bailey or Professor Smith, Dr. Bailey at first called the 
Japan form A. Ehrenbergii, and afterwards applied that name 
to the “A. Japonicus, Shadb.,” or African form. ~Smith has 
certainly not shown his usual sagacity in the elucidation of 
this genus; his generic character is nearly the same as Shad- 
bolt’s and Pritchard’s, but does not apply to the figure given 


162 WALKER-ARNOTT, ON ARACHNOIDISCUS. 


in his plate 31. I can only explain this by supposing that 
Mr. Tuffen West, in making the drawing had employed a 
specimen of the true Japan form, perhaps from Mr. Deane; 
while Smith had derived his generic character solely from 
African specimens, aided, perhaps, by Mr. Shadbolt’s figure, 
which he praises. In the African form there are irregular 
costee or lines connecting the radiating lines, in addition to the 
granules, and the granules are small; in the Japan form the 
granules are large, and placed in transverse rows, but there 
are no transverse costa. A slight comparison of Smith’s 
figure with Shadbolt’s or Pritchard’s will make this difference 
obvious. 

In the ‘ Mikro-geologie,’ Ehrenberg figures two species, 
both from earth, from the Island of Camorta, one of the 
Nicobar group. His 4. Jndicus is quite the same as the 
Japan one, having no transverse cost, while the A. Nico- 
baricus seems the same as the African form. 

If there be two distinct species, as is probable, the one 
may be called A. Ehrenbergii, to comprehend the Japan 
species, and that obtained by Dr. Bailey from California 
prior to 1853, as also A. Indicus of Ehrenberg: the other, A. 
formosus, to contain Hemiptychus formosus, Ehr., A. Japoni- 
cus, Shadb., and A. Nicobaricus, Ehr. I have already pointed 
out how these are easily distinguished. For A. Ehrenbergit 
I can only indicate the Japan seas, California, and the 
Nicobar islands, as the localities whence obtained. For A. 
formosus may be assigned a much wider range, as South 
Africa, Nicobar Islands, and West Coast of America. Which 
the British one is I cannot say; I fear there is a mistake 
about its occurring In our seas. 

It is not improbable that of 4. formosus there are several 
varieties ; in some, I find the transverse cost quite simple, 
in others, much and irregularly branched, like the vems of 
the leaf of a dicotyledonous plant, and in a form which I 
have from Mauritius (growing upon Plocamium Telfairia) , the 
radiating coste frequently (if not always with a good light) 
pass between the double row of puncta around the pseudo- 
nodule, and reach the pseudo-nodule itself; this structure 
requires to be verified from other localities ; it seems intended 
by Ehrenberg in his figure of A. Nicobaricus. 

In all that I have examined, taken from off the Alga, the 
lower valve is thinner, and sometimes differently marked 
from the upper one; the characters I have indicated are 
taken from the upper valve only. 

There can be no doubt that these dises have (as said by 
Shadbolt) a horny vegetable outer covering in addition to 


. 


WALKER-ARNOTT, ON ARACHNOIDISCUS. 163 


the siliceous one, and that by too long boiling in acid, as is 
necessary for guano, the marks are much obliterated, or en- 
tirely removed. This, however, is not peculiar to the present 
genus, but may be observed, more or less, in all diatoms, 
although sometimes the vegetable pellicle is very thin, and 
may be removed by a few seconds’ immersion in boiling nitric 
acid. Itis this circumstance which gives a quite different 
appearance to the same species, according as the preparafion 
is made. Thus, in Actinocyclus the vegetable epidermis is 
cellular, while the siliceous part is striated like a Pleurosigma ; 
and when the vegetable part is removed, we often find nodules 
or knobs along the margin (forming, then, the genus Ompha- 
lopelta), not previously visible. ‘Those who describe diatoms 
from slides are thus hable to commit great errors, and indeed 
no certainty can be obtained, except by getting the recent or 
growing diatom and examining it—lst, after being im- 
mersed for a short time im cold acid, or simply washed in 
boiling water; 2dly, after beimg boiled im acid for about half 
a minute, or a whole minute at most; and 3dly, after being 
boiled for a considerable time. We shall then see that many 
of the supposed distinct species of authors are the same, pre- 
pared in a different way. Of course deposits or guanos can 
yield little or no information; although once a species has 
been determined by the way I have indicated, we may be 
able to refer forms occurring in guano or deposits to it, with 
tolerable certainty. 

In my paper on Rhabdonema, in the last number of this 
Journal, I described the genus Eupleuria: since then I have 
found E. pulchella, not uncommon on Ballia, from Cape North- 
umberland, in South Australia. In that paper I noticed that 
E. incurvata differed from the others by the annuli not being 
cellular ; it is therefore probable, that it will have to be re- 
moved from the genus, particularly if the supposed annuli in 
that species prove to be only the siliceous connecting zone 
split, as it occasionally does in various other genera, into thin 
lamina. That this may be its true structure is rendered pos- 
sible by the discovery of a new genus from Mauritius, growing 
on Plocamium Telfairie (along with the Arachnoidiscus). This 
new genus has certainly no annuli: the upper and lower 
valves are as described in Hupleuria, and consequently it is 
intermediate between that genus and Achnanthes; differing 
from this last by the want of a stauros to the lower valve; 
by the costze not proceeding to the extremities, at least, on 
the lower valve; and by the valves being merely arched, 
and not geniculate; it has no stipes, and seems attached by 
the side, as in Kupleuria. To this genus the name Gephyria 


164 WALKER-ARNOTT, ON ARACHNOIDISCUS. 


may be given, the more especially that Hupleuria incurvata 
(my original Gephyria) may be removed here. The costi 
are about 6 in ‘001 in the Ichaboe species, while in the 
Mauritius one they are much closer, 15 im ‘001. This last 
may be called Geplyria Telfairie, after the late Mrs. Telfair, 
who discovered the Alga in which it occurs. In this the ex- 
tremities of the frustules are sharp; but I have, apparently, 
the same species from the West Coast of Australia (obtained 
by washing some Alge collected by Mrs. Drummond, and 
sent me by Dr. Harvey), but in that the frustules are more 
obtuse. 

In my former paper I described Amphiprora Ralfsit ; mm the 
same number (‘Trans.’) is a paper by Dr. Donkin, to which 
I find it necessary to allude, on account of the want of 
courtesy there shown (p. 33). When I transmitted my notes 
to Professor Smith, Mr. Ralfs, or others, they were to be 
held as mere notes ; and although any gentleman is at liberty 
to see them, or to use them, after verifying them, all that I do 
not myself publish must be regarded as private communica- 
tions, and with which my name is not to be connected, if 
published by others. Dr. Donkin gets some information 
from Mr. Roper, and Mr. Roper gets his from Dr. Mont- 
gomery, and Dr. Montgomery gets his from Mr. Ralfs, who 
gave a slide, with a name attached, which name I have now 
published. But I beg to say that Mr. Ralfs’ side was not 
from material discovered by me, as Dr. Donkin asserts, and 
that the identification of Dr. Donkin’s Plewrosigma rectum 
with my Amphiprora Ralfsii, was not made by me. If Dr. 
Donkin wishes to know what my species is, he must not 
go to a slide named by others, or by myself, containing 
several objects, but to my specific character,* for in drawing 
it up I had reference to several forms, both in Mr. Ralfs’ 
gathering and found elsewhere; and any one may see from 
it that several of Dr. Donkin’s supposititious species are 
combined under that character; im fact, Mr. Ralfs’ gathering 
contained, so far as I can comprehend his descriptions and 
figures, Pleur. rectum, Wansbeckii, minutum, and probably 
also angustum, which I consider one and the same species of 
Amphiprora. Pleur. carinatum I ought perhaps to add to the 
list, for I believe that the striz only appear oblique in con- 
sequence of the position of the light; if a true Pleurosigma it 
may be Pleur. obscurum, the only one with that peculiar ap- 


* T might have made the diagnosis more precise by saying the valves, 
although carinate, are not alate. This, however, is implied by not. noticing 
an ala. 


WALKER-ARNOTT, ON ARACHNOIDISCUS. 165 


pearance. Dr. Donkin will allow me also to add, that his 
S. V. and F. V. of Pleur. lanceolatum, belong not only to dif- 
ferent species, but to distinct genera; that his Plewr. arcuatum 
is only Pleur. fasciola: his Toxonidea insignis, the well- 
known distorted state of Pleur. estuart ; his Tox. Gregoriana 
the same of either Pleur. strigosum, or angulatum (I have 
seen both distorted), but which I cannot say from his imper- 
fect diagnosis of the species. His Cocconeis excentrica was 
discovered by De Brébisson, in 1852, and was then called by 
him C. orbicularis ; and his Epithemia marina, the HE, Radula 
of the same French gentleman, afterwards distributed in slides 
by Professor Smith as Nitzschia Radula ; this I have long had 
from the Clyde, and also Teignmouth. His Amphiprora 
duplex, judging from the figure and diagnosis, scarcely differs 
from A. paludosa. It is to be regretted that Dr. Donkin did 
not make himself acquamted with what others are doimg, 
before rushing into type; and that, stead of giving the long 
descriptions and figures, and multiplying species unneces- 
sarily, he had limited his species by a short, concise character, 
as every ¢rue naturalist must do who wishes his species to be 
adopted or considered by others. 


166 


TRANSLATIONS. 


Pretiminary Osservations on the Luminous Oreans of 
Lampyris. By A. KOuuixker. 


(From the ‘ Verhandl. d. Wurzb Phys. Med. Ges.,’ 130, VIII, 1857.) 


I. ANATOMICAL. 


1. Tur luminous organs of the various species of Lampyris 
are of a special nature and well defined ; not to be confounded 
with the adipose substance, and presenting a determinate 
form, size, and position. 

2. The males of Lampyris spendidula have two flattened 
luminous organs, appearing white to the naked eye, on the 
ventral aspect of the sixth and seventh abdominal rings; 
to which corresponds an uncoloured spot in the chitinous 
integument. The females have similar organs in the same 
situation, but in them the one situated in the sixth ring is 
double. Besides these, I find in the female Lampyris, four 
to five pairs of lateral organs, which are not always disposed 
symmetrically, and presenting the form of flattened globules, 
situated on the sides of the abdominal segments from the 
first to the sixth rg. The luminosity of these lateral organs 
is brightest when they are viewed from above. When not in 
a luminous condition, their pale transparent colour and deep 
position render them difficult of detection without careful 
dissection. 

The females of L. noctiluca have two larger, yellowish- 
white luminous plates on the ventral aspect of the sixth and 
seventh abdominal rings, and besides these, two minute 
organs on the eighth or caudal rmg. ‘The latter only, and 
these of a smaller size and grayish transparent hue by day- 
light, are present in the males of this species. 

3. All the luminous organs, both ventral and lateral, pre- 
sent essentially the same structure, consisting of an in- 
vesting membrane, enclosing a parenchyma composed of 
cells, trachee, and nerves. 

4. The envelope is a delicate, structureless pellicle, on the 
inner surface of which may be seen minute, very widely 
scattered nuclei. 

5. The cells of the parenchyma constitute a compact mass, 
occupying the whole interior. They are of a rounded poly- 


KOLLIKER, ON LAMPYRIS. 167 


gonal form, and from 0:01” to 0°02” in size. With respect 
to their contents, they may be divided into two groups,— 
the pale and the ‘white, between which, however, transitional 
forms may be observed. The former, or pale cells, contain 
pale, delicate granules, and in them may be perceived a 
minute, rounded nucleus; whilst the latter, or white cells, 
are so densely filled with white, spherical, minute eranules, 
having an oily aspect when viewed by transmitted light, that 
no other constituent can be seen in them. 

The disposition of these cells is such, that in the ventral 
luminous organs of the female of both species, and of the 
male in L. splendidula, the outer portion contiguous to the 
chitinous integument consists of the pale cells, whilst the 
inner or deeper part is constituted of the white. No very 
definite line of demarcation, however, can be drawn between 
the two. In the lateral, more detached, organs of the female 
L. splendidula, and in the luminous organs of the male of 
L. noctiluca the white cells occupy the entire surface. Al- 
though, as it appears to me, in the former the dorsal, and in 
the latter the ventral, aspect of the organs is less thickly 
covered with them. In certain cases, also, the white cells 
may be wholly wanting, or are represented by bodies con- 
taining only a few white granules. 

6. The numerous trachee enter from the upper, or, in the 
lateral organs, from the inner, side, forming the most abund- 
ant and elegant ramifications among the pale cells. The 
finest twigs of these vessels which appear to form loops were 
visible everywhere among the pale cells; but im the ventral 
organs they are the most numerous on that surface of the 
organ which is turned towards the external world, whilst in 
the others they exist all over the superficies. The chitinous 
integument of the larger tracheal trunks supplying these 
organs supports, as elsewhere in Lampyris, fine hairs. 

7. The nerves, which were not found except after prolonged 
and troublesome resear ch, enter the organs in company with 
the trachez and ramify among the pale cells, though by no 
means so abundantly as the trachez. They are of a pale 
aspect, here and there furnished with nuclei, and at the 
points of division also with nucleated enlargements, from 
which two to five branches are given off. The resemblance 
between the pale cells of the parenchyma and nerve-cells, 
suggested the possibility of some connection between the 
former and the nerves, but hitherto I have not succeeded 
in observing anything confirmatory of this supposition. 
The ultimate termination of the nerves, also, remained 
altogether in the dark. 


168 KOLLIKER, ON LAMPYRIS. 


II. PuystoLoGicaL. 


8. The proper luminous substance does not consist in the 
granules of the white cells, or the so-termed “ luminous 
granules” of Leydig, under which that author also includes 
some larger, radiated, opaque granules in the cells of the 
adipose body in the female of L. splendidula, but in the con- 
tents of the pale cells, as may be readily proved by direct 
observation of the luminous organs under the microscope by 
night, when the light of the lamp is shut off. 

9. The contents of these luminous cells correspond, in all 
their microscopical reactions, with an albuminous material ; 
although, owing to the extremely minute quantity of the 
substance which can be obtained, it has been impossible to 
subject it to a more satisfactory chemical examination. 

10. With respect to the granules contained in the white 
cells, as well as to the larger radiated globules in the cells of 
the adipose body described by Leydig, not merely and erro- 
neously as luminous granules, but also as composed of an 
inorganic matter, probably phosphorus! the simplest mi- 
cro-chemical examination shows, that they consist of a uric 
acid salt, which, so far as my experiments have hitherto 
shown, represents urate of ammonia (NH,O, Ur). On the 
addition of acetic or hydrochloric acid, the characteristic 
crystals of uric acid are very speedily formed; whilst with 
caustic soda and potass beautiful acicular bundles of the cor- 
responding urate are produced. In fact, if two or three of 
the luminous organs in L. splendidula are isolated by simple 
dissection, the murexid-test, by means of nitric acid and 
ammonia, may be directly applied, and will supply the most 
convincing proof of the true nature of their contents ; and on 
the subsequent addition of potass the characteristic purple- 
blue colour. will be obtained. The production of the arbo- 
rescent crystallization of sal ammoniac on the addition of 
hydrochloric acid, and the circumstance that no residue is 
left when the white substance is heated to redness, determine 
that the base of the uric acid salt in question is ammonia._ 

11. All endeavours to detect the presence of phosphorus 
in the luminous organs were fruitless. The organs of thirty 
males of L. splendidula were treated with sulphuret of carbon, 
and when this was allowed to evaporate on blotting paper, 
no luminosity was evident, nor was the paper charred. When 
organs which have been isolated by dissection are treated 
with nitrate of silver, no black precipitate is formed. The 
same was the case when a number of the insects were placed 


KOLLIKER, ON LAMPYRIS. 169 


in a small glass vessel and covered with a shallow dish, con- 
taining a drop of a solution of the same salt. 

12. The luminosity of Lampyris is dependent upon the 
will of the animal, and exists by day as well as at night, 
though very frequently absent in the day time; a circum- 
stance evidently depending simply upon the fact that these 
insects are, for the most part, nocturnal in their habits, and 
usually lie concealed in the dark during the day. Movements 
alone have no influence upon the production of light; and 
even in the night time, individuals may be noticed performing 
the most active movements, and yet showing no luminosity 
whatever. Nor, also, has the concentration of light upon 
the animals any effect; whilst they exhibit luminosity even 
when they have been kept for days together in the dark. 

13. Many irritants exercise an influence upon the produc- 
tion of light, amongst which the following may be noticed : 

(1.) Mechanical irritation —The crushing of the luminous 
organs, or even a slight pressure upon them, from without, 
invariably causes brilliant illumination. When the organs 
are divided into small portions, or torn in pieces, the lumi- 
nosity soon ceases. The light is also frequently manifested 
when the head or thorax of the insect is cut off or slowly 
crushed. 

(2.) Electrical irritation—If the whole insect, or even 
only its abdomen, when the luminosity is not present, is 
excited longitudinally by a powerful induction-current, the 
most brilliant illumination is instantaneously produced, which 
usually quickly disappears again when the current is inter- 
rupted. The same effect is produced when the poles are ap- 
plied directly to the organs, and very frequently also when 
the head alone is excited. 

(3.) Temperatures—From the experiments of Kunde and 
myself, which agree pretty nearly with those of former 
observers, a temperature of +40° to + 60° R., always excites 
a bright luminosity; and the same effect is produced, though 
more rarely and with less certainty, by a temperature of 
from — 3° to — 5° R. Under variations, also, of temperature 
amounting to about 30° C., the luminosity is produced, as it is 
almost always when the animal is transferred from a freezing 
temperature to the warmth of the hand. 

(4.) Chemical irritants.—In these experiments, the sepa- 
rated abdomen only was always submitted to the reagent, with 
which the part was in all cases kept completely moistened. 

a. Caustic alkalies are powerful excitants of the luminous 
organs—caustie potass, in fact, acting im all degrees of con- 
centration, from 0°7 to 50 per cent. 

VOL. VI. ) 


170 KOLLIKER, ON LAMPYRIS. 


b. Acids —Very beautiful luminosity is produced by sul- 
phuric, nitric, and hydrochloric acids, and in the case of 
sulphuric acid, solutions containing from 75 to 75} per cent. are 
efficient for the purpose ; hydrochloric acid acted in solutions 
containing from 3 to 25 per cent.; mitric acid was tried, with the 
same result, in a solution containing 22 per cent., which was 
the only strength tried. The vapours, also, of the two latter 
acids act as excitants of the luminous organs. Besides these, 
a similar effect is produced by phosphoric, concentrated 
acetic, tartaric, citric, oxalic, and a five per cent. solution of 
chromic acid. 

(5.) Solutions of indifferent substances, in certain degrees 
of concentration, are also excitants of the luminous organs, 
such as the haloid salts and the neutral salts of the alkalies and 
earths, as well as sugar. Common salt acted as an excitant 
in solutions containing 3 per cent. and upwards, phosphate 
and sulphate of soda, in solutions of 4 to 5 per cent. 

d. Other excitants are alcohol of 45 per cent. and upward, 
anhydrous ether, creosote, lunar caustic, chloroform, and 
chlorine. 

e. No effect is produced by water, saliva, strychnia, dilute 
solutions of salts and acids, oils, sulphuret of carbon, and 
many metallic salts. Oxygen, also, from a single experi- 
ment, would not appear to be a true excitant, for separate 
abdomens, and entire insects not in a luminous state, fre- 
quently do not exhibit any luminosity until after one or 
several hours; but then, it is true, they shine long and 
brilliantly. 

14, The luminous property is destroyed by a great many 
influences, although it always exhibits great tenacity. It is 
always and speedily annihilated bythe mineral acids and caustic 
alkalies ; and also—a circumstance that appears to me of 
especial interest—by narcotics, which paralyse the nervous 
power, as by the fumes of hydrocyanic acid and of conein 
(experiments with the urara poison were unsuccessful). 

In the experiments made with these poisons, the 
animals under proper precautions for the protection of 
the experimentalist, were placed in a small watch-glass, 
and moistened with saliva; the watch-glass was then 
introduced into a larger vessel containing the poisonous 
vapour, so that the atmospheric air had free access. If 
the insects experimented on were in a luminous condition, 
the light was extinguished in from three to five minutes, and 
at the end of five to ten minutes the luminous organs were 
quite dead, and incapable of excitation by any means— 
crushing, electricity, and caustic alkalies. The same effect was 


KOLLIKER, ON LAMPYRIS. 171 


produced when non-luminous individuals were exposed to the 
poisonous vapours in question. The luminous organs were 
in like manner destroyed by a powerful electric current, 
alcohol, ether, organic acids, &c. 

Of other injurious agents, many, at any rate, do not neces- 
sarily annihilate the luminous property for ever. ‘Thus 
animals which have been dried, are resuscitated when mois- 
tened with water, and exhibit luminosity ; and, in the same 
way, individuals benumbed by cold (0° to — 5°) are revived 
by the warmth of the hand. Moreover, I have succeeded in 
restoring the luminous property of entire insects, and of 
isolated organs, which had been deprived of it by a solution 
of salt containing 12 to 20 per cent.—that is to say, by the 
forcible abstraction of water, by immersing them again in 
water. There is thus no doubt that further experiments will 
show, that, in the case of these organs, pretty nearly the 
same phenomena of revivification take place as in the sper- 
matic filaments and nerve-fibres. 

Under favorable circumstances, the length of time during 
which the excitability of the luminous organs is maintained, 
and the light itself may be produced, is very considerable. 
In moist atmospheres, as well as in diluted solutions of 
salt, sugar, and albumen, the separated abdomen will often 
continue in a luminous condition for twenty-four to thirty- 
six hours. The greatest length of time during which I have 
noticed the luminosity to continue, viz., forty-nine hours, 
was in a moist atmosphere of oxygen. In water, that is to 
say, when the animal is moistened all over, the luminous 
property ceases to be manifested in a rather short time— 
usually in one to three hours. 

15. When insects moistened with a solution of salt were 
placed with the cephalic and caudal extremities on the 
cushions of Du Bois’s current apparatus, those in a luminous 
condition, and especially females, deflected the needle of the 
multiplier from 3° to 7°, the head at the same time appearing 
to be positive. This result, however, was not quite constant, 
and further experiments will be necessary before any further 
conclusions can be safely drawn from it. 

Non-luminous animals, even when they moved on the 
cushions, usually afforded, with my multiplier of 16,000 
turns, no indication whatever of a current, or, at most, did 
not deflect the needle more than 1° or 2’. 

16. I was very desirous of determining whether there was 
any difference of temperature between the luminous and non- 
luminous animals, but owing to the circumstance that the 
experiments were delayed till quite the close of the season in 


172 KOLLIKER, ON LAMPYRIS. 


which the insects appear, the only result at which I arrived 
was, with the aid of the thermo-electrical apparatus, to 
determine that the temperature of the non-luminous females 
was 17°C., in a room at the temperature of 20° C. 


Results. 


From the foregoing experiments, coupled with the anato- 
mical facts, I conclude that the luminous organs are a ner- 
vous apparatus, whose nearest analogues might be sought 
in the electrical organs. All excitants of the nerves excite 
the luminosity, and the agents which annihilate the nervous 
functions, act injuriously in their case also. My experiments 
wholly subvert the theory hitherto current, which assumes 
the existence of a luminous material, secreted and deposited 
in the organs, a sort of phosphorus, which, on the addition of 
oxygen through the respiratory movements, becomes oxy- 
dized, and consequently luminous. It must, indeed, be a 
strange material which may be rendered luminous by acids 
and alkalies, alcohol and creosote, salts and sugar, and has 
its luminosity destroyed by prussic acid and conein. It 
seems to me that the observations above detailed are capable 
of but one explanation, viz., that the light is produced under 
the influence of the nervous system, and in all cases is main- 
tained only for such a period, whether long or short, as the 
nerves, stimulated by the will or otherwise, act upon the 
organs. With respect to the proximate causes of the light, 
I have thought of the electrical light, and on light produced 
by chemical action. Whether the former supposition be 
worth further investigation, or whether it be at all possible— 
by analysis of the greenish light of Lampyris, which micro- 
scopical examination shows to consist of minute sparks—to 
determine whether it be electrical or not, I will not 
venture to decide. I am at present inclined to prefer 
the second hypothesis, which also seems to be sup- 
ported by the fact of the presence of urate of ammonia 
in the luminous organs, as my experiments have shown. 
Admitting that these deposits, from their position and their 
being composed of very minute granules, may add to the 
light of the luminous substance itself, still, seeing that 
their number is very variable, it appears more probable to 
refer their production to molecular changes in the luminous 
matter, and to assume that the latter, which manifestly con- 
sists chiefly of an albuminous substance, and is abundantly 
supphed with oxygen by its numerous trachez, undergoes 
during life a decomposition, one of the ultimate results of 
which is urate of ammonia (NH,O, Ur). 


PRINGSHEIM, ON ALG. 173 


The evolution of light, therefore, would be an accompani- 
ment of this decomposition (oxydation) of the albuminous 
material, though it must of course be assumed that the de- 
composition takes place under the immediate influence of 
the nervous system ; in fact, even, it may be said that this 
decomposition takes place so actively as actually to be 
attended with the luminous phenomena, only in consequence 
of its imtensity derived from the nervous influence, whilst, 
under ordinary circumstances, albuminous substance, under- 
going oxydation, is not luminous. If this explanation be 
correct, we are here presented with another remarkable 
instance of a direct influence exerted by the nervous system 
on molecular changes, and which, although ina certain sense 
analogous to what we know of the influence of the nerves 
upon the electrical organs and salivary glands, as well as in 
the action of the nerves upon the muscles, still at present 
appears to be suit generis. 

So much for the present. I hope next winter to be able 
to publish my experiments more in detail, with the requisite 
illustrations, although I may wait for another glow-worm - 
season, in order to supply many existing deficiencies in my 
observations. In any case, I shall then make due reference 
to the numerous previous researches on the subject of the 
luminosity of Lampyris, amongst which, as [ will at once 
remark, the most satisfactory are those of my countryman, 
Macaire, of Geneva (‘ Bibl. univers. d. Genéve,’ 1821, and 
Gilbert’s ‘Annalen, 1822, p. 265), and endeavour, at the 
same time, to bring into one view the physiological relations 
of luminous animals in general. 


PrincsuerM’s Researches on the Fecunparton of the Aucam. 
By M. Monraenzt. 


Tue following résumé, by M. Montagne, of Pringsheim’s 
later researches on the fecundation of the Alge, appears 
in ‘ L’ Institut’ for August 20th, 1856, and may be regarded 
as a continuation of what has already appeared on the subject 
in this journal. 

“The second memoir of M. Pringsheim,” observes M. 
Montagne, “is full of curious facts, leading to unexpected 
results, and well deserves the attention of naturalists. It 
contains, in fact, the establishment of the existence of the 


174 PRINGSHEIM, ON ALG. 


two sexes in some fresh-water Algee—the Conferve, in which 
their existence had previously been scarcely suspected. It is 
true that the motions of certain spores (zoospores) at matu- 
rity had been remarked, and that this motion was caused 
by the action of vibratile cilia, with which they are fur- 
nished. Their germination even had been traced. But as to 
antherogoids, or male organs, I know of no observer before 
M. Pringsheim who had noticed them in the lower Alge, 
and particularly in Cidogonium, one of the subdivisions of the 
genus Conferva of Linnzus. 

“Nothing is more marvellous than the phenomena attend- 
ing the act of fecundation of these plants. The sexual appa- 
ratus, the metamorphoses that the androspore or male organ 
undergoes, and the act of fecundation itself, seem so many 
facts contrived on purpose to excite our utmost wonder and 
admiration. 

“The species of Gidogonium are simple, filamentous Alge, 
living in fresh water, and composed of cylindrical cells placed 
end to end in a single series. They present this peculiarity, 
that. the greatest number of species are marked by annular 
striz placed on certain special cells. In one of these cells, 
at the time of reproduction, the contents accumulate, become 
condensed and distended, and sometimes produce zoospores ; 
sometimes a single spore, which is detached, and falls to the 
bottom of the water, when mature, to perpetuate the plant. 

“This is all that was formerly known. We were completely 
ignorant of what indueed the successive changes that the spore 
underwent before it was detached. This is what M. Pring- 
sheim has observed. In the same filament which produces 
the female cells destined to propagate the plant, others may 
be observed, generally shorter, in which bodies are developed 
which might be compared to antheridia, since they enclose 
the antherozoids. These bodies, ovoid, crowned with vibra- 
tile cilia, and called by the author androspores* (Andro- 
sporen), very closely resemble zoospores, but are very 
differently organized. Escaping from the vesicle which in- 
closes them, these androspores attach themselves at a deter- 
minate moment firmly on the female cell. The filament, 
whole and unbroken until now, opens its joints at the level 
of one of the striz like a soap-box, to allow of the protrusion 
of the membrane containing the gonimic matter or the 
potential spore. This protruding portion, which the author 
calls fecundating tube (Befruchtungschlauch), is perforated 
by a round opening at the spot where the androspore had 


s, * These are the organs which have been termed Microgonidia by Alex. 
raun, 


PRINGSHEIM, ON ALGZ. 175 


implanted itself, a sort of ambulatory testicle for which I can 
find no comparison. The act of fecundation takes place, 
after the fall of a little operculum from the androspore, by 
the introduction of a spermatozoon, or Saamenkirper, as it is 
called by M. Pringsheim, into the mass of endochrome 
(chromule) of the female cell. This introduction is effected 
through the lateral opening existing at the summit of the 
fecundating tube, and which performs the part of a micro- 
pyle. Before this act, the female cell, in order to permit the 
entrance and action of the spermatozoon destined to com- 
municate the germinating faculty to the spore, remains open, 
but no sooner is the act accomplished, than the cell surrounds 
itself with a second membrane which prevents any further 
intrusion.” 

Such are the facts observed by M. Pringsheim. But, adds 
M. Montagne, “we must not forget that it is to French 
naturalists we are indebted for the first information on these 
interesting questions. It was a member of this Academy, 
the illustrious Reaumur,* who first thought of seeking for 
the two sexes in the Algze, and but little more would have 
given the honour of this discovery to him. It was nearly a 
century and a half after his fruitless researches, that two 
botanists more fortunate, M. Decaisne and M. Thuret, suc- 
ceeded in establishing the existence of antherozoids in the 
same receptacles of the Fuci where Reaumur had vainly 
sought for and thought he had found male fiowers. Since 
then, the Academy of Sciences, in proposing as the subject 
for the grand prize in natural history, in 1847, the study of 
the zoospores and the antheridia of the Algae, excited 
renewed efforts on the part of M. Thuret, and of MM. Derbés 
and Solier—efforts which have been rewarded, and which 
have given a new impulse to these studies, the effect of 
which we now see in the observations of many phytologists, 
amongst others of M. Pringsheim, and of which it is as im- 
possible to calculate the consequences as to limit the term. 

“J will add, in conclusion, that all observations published 
up to this time on those families of the vegetable kingdom 
in which species of the most simple organization are met 
with, goes to prove that the law which governs the function 
of reproduction is becoming more and more generalised, and 
that, with some modifications dependent on special conditions, 
it is common alike in plants and animals.” 


* Reaumur, “ Description de fleurs et de graines de divers Fucus,” &e., 
‘Mém. de l’Acad. des Sc.,’ 1711, p. 381, and 1712, p. 21. 


176 


REVIEWS. 


Introduction to Cryptogamic Botany. By the Rey. M. Te. 
Berkexey, M.A., F.L.S. London: H. Bailliere. 


TuereE is no department of natural history that has been 
more indebted for its progress to the employment of the 
microscope than that of the structure of Cryptogamic Plants. 
So little was the nature and structure of these plants known, 
that Linnezus applied to them the term Cryptogamia, on 
the supposition that no process of reproduction existed in 
them analogous to that which occurred in the stamens and 
pistils of higher plants. The history of the discovery of the 
reproduction of these plants, by the agency of sperm-cells 
and germ-cells, is one of the most brilliant pages in the re- 
cords of microscopic research. Although their structure has 
been well described and illustrated in the works and papers 
of Lindley, the Hookers, Henfrey, Berkeley, Broome, 
Thwaites, Ralfs, and the late William Smith; till the publi- 
cation of the present work by the Rev. M. J. Berkeley, we 
had no book in our language especially devoted to the con- 
sideration of their structure and affinities. Few persons could 
bring to this task more qualifications than Mr. Berkeley. He 
has devoted unusual powers of observation and careful re- 
search to the study of the Fungi, and is known for his work 
on the British forms of this family, wherever the science of 
botany is cultivated. In this work he has devoted the same 
qualities of mind to the revision and criticism of all that has 
been done by other observers in the remaining families of the 
Cryptogamia, and has produced a volume that will be valued 
by all who are engaged in the study of this most interesting 
and important branch of scientific vestigation. Not only 
does Mr. Berkeley’s work give a very complete account of the 
various families of Cryptogamic plants, but it contains a large 
amount of philosophical reflection and sound advice, which 
cannot but be useful to the young student. In his introduc- 
tory chapter he especially draws attention to the value of 
researches on the lower plants ; and points out the errors those 
are likely to fall into, who, whilst skilful in the use of the 
microscope, have neglected the first principles of scientific 
inquiry. We give the following extract as an example. 


“T shall not dwell upon the extreme and manifold interest of the several 


BERKELEY, ON CRYPTOGAMIC BOTANY. 177 


objects which come within the view of the Cryptogamist. If variety and 
delicacy of structure, beauty of form and colour, and the nicest transitions 
from group to group, from genus to genus, besides a host of curious ques- 
tions of {physiology and adaptation of means to particular ends, are worthy 
to engage attention, Cryptogams most surely will not be amongst the 
most unprofitable objects of study. There will be scope, too, for the acutest 
powers of thought and observation, unless he is content merely to skim the 
surface of things. Even independently of the necessity of using optical 
instruments, a point often much exaggerated, for if the minutest points of 
physiology in Phenogams are deeply studied, no less an amplifying power is 
necessary, and perhaps even greater tact and skill in manipulation, the dif- 
ficulties which arise from the wide limits within which not merely species 
but aceredited genera are capable of varying, are sufficient to exercise the 
highest mental qualifications. It does not follow, however, that the end 
obtained should be at all proportional to the necessary labour. The objects 
which the accomplished Cryptogamist has in view are not comprised within 
the mere determination of species or the admiration of the exquisite forms 
and combinations which meet him at every turn. If he aims at nothing 
higher than the first, he may indeed be useful in his generation, provided he 
be cautious enough, and possessed of sufficient self-denial to prevent his 
striving to glorify himself, rather than to clear the road for investigators of 
higher pretensions. If beauty of form and singularity of structure be alone 
his object, his time may be passed agreeably enough, but in most cases, like 
ten thousand microscopists of the present day, he will be but a mere trifler, 
without any better aim than innocent amusement; or if he be a dabbler in 
science, with some wish to attain a reputation which he has not the patience 
to seek after by a continued course of study and mental discipline, he will 
be deriving general inferences from isolated half-understood facts to the 
detriment and confusion of real science. Perhaps, of all literary dissipation, 
the desultory observations of the mere microscopist are the most delusive. 
And even where the objects are higher, it is well that every one whose 
attention is much directed to this greatly abused instrument, should remember 
that if he wishes to penetrate the secrets of nature he must look beyond his 
microscope, a fact of which some microscopists of considerable reputation do 
not seem at all aware. The paramount importance of the subject is to be 
seen in far different matters. 

“The first great point is that the physiologist is able, in the simpler 
Cryptogams, to study the several organs of which the higher vegetables are 
composed, isolated and altogether removed from other structures which may 
impede the view, or by their rupture cause confusion. If, for instance, it is 
desired to ascertain the mode of growth in cells, he will be able to appeal to 
the simpler Alge, whether grumous or filamentous. In the one he will be 
able to trace step by step the division of the primitive mother-cell, with 
nothing to prevent his view in consequence of the great transparency of the 
walls; or if he take one of the simple or branched Conferve, he will be able 
to assist at the origination not merely of two new cells from the subdivision 
of one, but the formation of a new cell by pullulation from the walls. 
Meanwhile he can ascertain exactly what changes the endochrome is under- 
going, he can watch the part which the cytoblast bears in the process, and 
can sometimes trace its partition. He can investigate in many cases, as in 
Zygnema and its allies, or much more in Chara and Nitella, the currents 
which traverse the length and breadth of the cells; he can trace thickening 
of the walls by the deposit of new coats, and in some cases the shelling off 
of those which are effete and have performed their office. He can observe, 
moreover, the wonderful union of separate filaments, the formation of a vital 
spore from the union of the contents of neighbouring cells, and many other 


178 BERKELEY, ON CRYPLOGAMIC BOTANY. 


points of interest, which throw more or less light on the processes which 
occupy the attention of the investigator of the vital processes of the higher 
vegetables. Amongst the lowest vegetables he will find many facts wliich 
will give him points of comparison with inmates of the animal kingdom; he 
will see apparent Infusoria existing as mere vegetable organs, and will find 
them performing functions under a form which he will in vain hunt for 
amongst the higher vegetables, and if his attention be turned to those 
Cryptogams which more closely resemble these in outward appearance, he 
will find a form of spermatozoid so closely resembling the impregnatory 
bodies of the higher animals, as to open his mind more strongly than ever to 
a conviction of the intimate bond by which all the members of the organized 
world are bound, though he may not subscribe to those theories which deny 
the existence of definite groups. There can be no question in these cases of 
the spermatozoids being developed in perfect freedom within the mother- 
cells, and not mere appendages separated from their walls, and endowed. 
with a vital action, similar to that of the cilia, so common to mucous sur- 
faces, as many animal physiologists assert. Such investigations will come 
in aid then of those relative to the development of spermatozoa in animals, 
and similar advantages will be presented in many other instances, and con- 
sequently the cryptogamic student will be able to form more exact notions 
as to vital action in the animal and vegetable kingdoms than are usually held 
by those who confine their investigations to either division of the organized 
world. Again, though spiral vessels are comparatively rare in Cryptogams, 
opportunities of studying their development and nature are nowhere more 
available than amongst the Hepatice, where they occur without the inter- 
vention or attachment of any other issue, while in Zyguzema the curious and 
multiplied spiral bands may with ease be traced from the first formation of 
the cells in which they are developed. 

“There is another point of immense importance, which the cryptogamic 
observer has in a peculiar degree the power of studying successfully. Ques- 
tions often arise as to the point whether cellular structure can originate 
without the presence of a previous mother-cell. It is a question, for in- 
stance, whether cells are ever formed in Phanogams from mere organizable 
sap, as presumed by Mirbel in his paper on the Date Palm; or again, 
whether, in what is called organizable lymph in the animal world, cells can 
originate freely without pullulation from the neighbouring tissue with which 
the lymph is in contact. In the blood, once more, are blood-globules, or in 
unhealthy conditions, pus-globules, ever formed simply from the constituents 
of the blood itself, without the concurrence of previously formed organisms ? 
Now in those fungi in which, as in Spheria and Peziza, the reproductive 
bodies are generated by the endochrome of the fructifying cells, the Cryp- 
togamist has the power of watching the development of the spores from 
the very moment when the endochrome commences to be organized, 
and he can with confidence assert that they are not the creatures of pre- 
viously existing cells, but the produce of the endochrome itself. He 
will be able to compare with this what takes place in the embryo sac of 
Pheenogams, and will be better prepared to appreciate all the arguments 
which bear upon the Schleidenian Theory of the formation of the embryo. 
Both the formation of the albumen and of the embryo itself will then be 
studied with greater zest, and he will certainly, after watching the origin of 
spores within an ascus, be able to judge better of what takes place or does 
not take place within the pollen tube. It is true that many of the points [ 
have mentioned may be examined profitably in Phenogams, but always 
with more difficulty, and seldom with such precision or with such satisfac- 
tion and conviction to the observer, and there is one point which must 
always be borne in mind, that the objects in question grow and are developed 


BERKELEY, ON CRYPTOGAMIC BOTANY. 179 


under his eyes, if he possesses proper powers of manipulation, which will 
searcely ever be the case with Pheaogams, if the parts be freed ever so 
neatly from the surrounding tissues. Nay, the examination of the develop- 
ment of cells in such genera as Hematococcus and Gleocapsa will help even 
the Zoologist, for nothing ean be more close than the mode of development 
in these, and of the vitellus in the eggs of certain Mollusca. 

“The bodies, indeed, which are so much alike, or in other words, are 
homologous, identical, that is, in structure and genesis, though not in func- 
tion, may not always be of equal value; but the student will learn as much, 
perhaps, from the observance of their differences, as if they were in every 
respect perfectly accordant.” 


Some of the earlier of these remarks may perhaps be 
regarded as seyere, but they are the result of the observation 
and reflection of one who has entitled himself to be regarded 
as a master of the subject on which he writes, and must be 
received with all due respect. The following passage is on 
a subject which has recently undergone discussion in our 
pages, and will be read with interest. 


“Nor will a few words on this subject of species be completely out of 
place, though we have incidentally touched on it before. It is one which 
the cryptogamic student will meet with at every turn. It is a common 
opinion that cryptogamic species are so variable, that it is impossible to cir- 
cumscribe them with specific characters; and, to be studied with certainty, 
they must be studied in the herbarium. ‘The practised eye will there detect 
similitudes between widely different forms which no definition could convey. 
Now there is certainly much truth in this notion, but more perhaps, from 
the wrong conception of authors than from the intrinsic difficulty of the 
case. So long as essential characters are neglected, and fleeting external 
characters put in their place, difficulty must needs exist, and the student 
will never be certain that he has come to a correct decision till he has seen 
an authentic specimen, or compared his own decision with that of other 
botanists as manifested in extensive herbariums. A state of uncertainty is 
always one of more or less pain, and the temptation to a solution of the dif- 
ficulty by the supposition that he has made some new discovery, will often 
present such attractions as to prove insurmountable. Nor will he find it 
possible, without that mental discipline which arises from a patient study of 
every detail of structure, and of the various shapes which organs may assume 
under different circumstances. Without such discipline, like certain German 
authors of some repute amongst persons uninstructed in the subjects they 
profess to handle, he will propose a new name for every difference, even such 
as are manifestly merely temporal and accidental, and, on the contrary, he 
will unite whole groups which belong to entirely different categories. It 
would be easy to point out glaring examples, both amongst algologists and 
mycologists. One of the worst amongst Phenogamists, perhaps, is the 
erection of that state of the inflorescence of several species of Cissws, in 
which the peduncles are deformed by the presence of an internal parasite 
(Puccinia incarcerata, Lév.), into a distinct genus of Phenogams; though 
this is not worse than referring the same Alga received from different 
sources to two or more distinct genera, and that not among the lower or 
more obscure species, where there might be some excuse for such a pro- 
ceeding, or the association of plants so totally different, as Puccinia and 
Trichothecium. Nor is the correct appreciation of species of so little 
consequence as is sometimes vainly supposed. ‘The only way in which 


180 BERKELEY, ON CRYPIOGAMIC BOTANY. 


we can arrive at anything like accurate views of geographic botany, 
or the distribution of plants over the globe, is by a correct estima- 
tion of species. If two Floras be formed on different principles—while 
in the one the species are accurately limited, and forms which vary only in 
some subordinate point, and not in essential characters, are grouped under 
one common name; in the other, not only every marked variety, but even 
accidental variation, is elevated to the rank of a species,—it is impossible 
to form any correct comparison, and this is the more necessary in Crypto- 
gains than elsewhere, because the species have notoriously such a wide 
diffusion, and because their technical, though not their essential characters, 
are so very variable. The great point in all these cases is never to describe 
from single or imperfect specimens, where there is some form evidently very 
closely allied. It may not be possible, perhaps, always to avoid error, but 
a little caution will be most advantageous, both as to one’s own individual 
character as a botanist, and to science in general. And if species are once 
accurately characterised, there will be far less difficulty than may be imagined 
as to genera. Nothing is more vain than to run down botanists as mere 
makers of species, as though it did not take as much knowledge and tact to 
limit species well, as to ascertain a few detached microscopical facts without 
deriving any general views from such study, or ever seeing the relative 
bearing of such observations. ‘The physiologists of the present day, at 
least too many who have some name in science, are absolutely doing the 
very thing which they profess to despise in species-makers. A proposer of 
bad, ill-defined species is no promoter of science; still less is the so-called 
physiologist who draws from isolated half-observed facts, conclusions which 
the very next observation may entirely destroy. We may regret, indeed, 
sometimes the over-caution of the prince of physiologists, but such over- 
caution is ten thousand fold more praiseworthy, and tends more to the 
advancement of science, than crude, hasty, and ill-considered theories founded 
on imperfect observations, because what it does bring forth is essentially a 
KTnpa €¢ ae, and, even when incomplete, is a sure stepping-stone for the 
acquirement of some further eminence.” 


As we at first stated, it is in the structure of the repro- 
ductive organs in Cryptogamic plants that most has been 
done by the aid of the microscope. On this subject we 
extract the followimg passage from Mr. Berkeley’s luminous 
introductory chapter. 


“ Tt is desirable, again, before entering further on this argument, to say 
a few words on the reproductive organs of Cryptogams, at least on the 
female organs, for there is little or no similarity between the male organs of 
Cryptogams and Phenogams. There are no proper pollen globules, no 
germinating of a cell to bring the walls in contact with the embryo-sac; nor 
is there any agreement between the mode of generation of the grumous 
matter or fovilla and the spermatozoids. 

“In the more simple cases there is nothing at all analogous to flower, but 
certain privileged cells are separated from the threads or compact tissue of 
the matrix, whether naked, or produced within a special tube or sac, and 
constitute the fruit. ‘These germinate almost exactly like pollen grains, and 
reproduce the species. ‘There are, sometimes, several kinds of spores upon 
a plant, all capable of reproduction, though differing in appearance. These 
spores, then, are homologues of the individual cells of Phaenogams, which, 
at times, are equally capable of reproduction in the shape of buds. 

“The spores, or what have the appearance of spores, do not always 
reproduce the plant immediately, even in plants of such a low grade as 


BERKELEY, ON CRYPTOGAMIC BOTANY. 181 


Fungi. In the higher Fungi, certain cells swell and become clavate, pro- 
ducing on their surface a number of little points, each of which is terminated 
by a spore. In remella, this clavate swelling has much the appearance of 
fruit, but the points upon its surface are greatly elongated, and true fruit at 
last is produced. In certain cases, these spores produce from their surface 
minute processes, supposed by Tulasne to be male organs. These can only 
be seen with a nice adjustment of the light. Their existence has been 
verified by myself and Mr. Broome; their functions, however, at present 
must be considered doubtful. In the gelatinous fungus, which is so 
comnion on Juniper (Podisoma), the bodies I have represented are very like 
these sporophores in Tremella, but they germinate truly like other spores, 
and are remarkable for germinating at definite points. The threads they put 
out produce in fact the true fruit. This holds good equally of all the blight 
or rust-like Fungi, such as affect corn and other living plants. 

‘A different order of things prevails amongst the higher Cryptogams. 
The spores germinate and produce a more or less foliaceous mass, which 
after impregnation bears fruit containing bodies like the original spores, or 
a plant capable of bearing such spores, in which case it is called a prothallus. 
After a time, certain pitcher-like processes project from it, or are sunk in 
its substance. A cell at the base of these urns, when impregnated, grows 
after the fashion of the first cell of the embryo in Phenogams. In some 
cases, then, the cells which arise from germination are developed, as in 
mosses, into a plant directly, reproducing spores by which the cycle is again 
accomplished ; in others, as in Ferns and Club-mosses, an embryo more or 
less resembling those of Phznogams is first generated, which strikes root 
and sends out an ascending stem, which sometimes grows into an enormous 
tree, producing every year a crop of spores. The spores, then, in these 
different plants are of very different values, and in no respect homologous 
with the seeds of plants. Cryptogams have, in fact, no true separable 
seeds, though, in the highest forms which they assume, they generate an 
innate embryo. Without some such notion, though I am obliged to antici- 
pate matters to be described more fully hereafter, 1t is scarcely possible to 
estimate the true relations of Cryptogams to Phenogams.” 


In gomg through this work we had marked several 
passages as adapted for introduction into our pages, but 
these are so many, that we can only recommend our readers 
to purchase the volume, in order to become acquainted with 
them. We must, however, give one more illustration from 
the details of the work, and this one we take from Mr. 
Berkeley’s account of the Hyphomycetous Fungi. To this 
group belong that very interesting series of organisms known 
by the name of moulds. 


“The species contained in the division Hyphomycetes, consist of Fungi 
which, like Mucorini, are known under the common name of moulds. All 
organized matter is soon compelled by their agency to undergo chemical 
change, or when chemical change has taken place supplies a fitting matrix 
for their development. ‘The common blue mould of cheese, the brick-red 
cheese mould, and the scarlet or orange strata which grow on tubers or 
roots stored up for use, when commencing to decay, are familiar examples. 
Nothing, however, escapes their ravages. The silk or cloth stored up in 
our wardrobes, the meal and sugar of our kitchens, nay, the very glass of 
our windows, suffer in greater or in less degree. Ina few cases, as in cheese, 


182 BERKELEY, ON CRYPTOGAMIC BOTANY. 


their growth is encouraged, and steps are even taken to inoculate untainted 
cheeses; but in other instances they are a destructive poison, unless, indeed, 
the evil effects which have arisen from the use of certain mouldy provisions 
are to be ascribed to the decomposition of the matrix, rather than to the 
mould itself. Some of the species are developed with extreme rapidity, and 
a few years since, when the barrack bread was so much affected at Paris by 
a species of Penicillium, a very few hours were sufficient for its development, 
and the mould was in active growth almost before the bread was cold. 
Indeed, it was proved satisfactorily that the spores of this species are 
capable of enduring a temperature at least equal to that of boiling water, 
without losing their power of germination: Such facts, then, are no proof 
of spontaneous or equivocal generation. Dutrochet found, indeed, that the 
chemical nature of substances had great influence on the species which grow 
upon them, and that albumen was almost a perfective preventive. This, 
however, is simply in accordance with facts relative to the distribution of 
Phenogams over the surface of the earth. The chemical composition of the 
soil has a great deal to do with that distribution. The occurrence of 
moulds in closed eavities has been mentioned above, and the extent to which 
the spores or other reproductive bodies insinuate themselves in the most 
deeply tissues. Dutrochet professes to have seen milk-globules changed 
into the spores of moulds, or at any rate developed into moulds. Certain it 
is, that when milk is arrested for a long time in the udder of the cow, and 
forms clots there, moulds are frequently found, and that they find their way 
into cavities which are almost closed to external influences, as in the urinary 
bladder of man, and that under more than one form. Such anomalies may 
at first surprise us, but they may, nevertheless, admit of explanation, as the 
presence of the larvee of tape-worms in deep-seated organs, and even in the 
brain, which was so long a stumbling-block of science. On surfaces freely 
exposed to the air, as the pulmonary cavity, or communicating with it occa- 
sionally, as the walls of the stomach, they are not unfrequently developed, 
under peculiar conditions of disease. 

“One of the most remarkable qualities possessed by certain moulds is 
the power they have of producing or accelerating fermentation. Yeast is, 
in fact, nothing more than a peculiar condition of a*species of Penicillium, 
which is capable of almost endless propagation, without ever bearing perfect 
fruit. Attempts have been made to show that the structure of yeast- 
globules is different from that of ordinary moulds, but without success. 
It appears that wherever exosmose and endosmose take place, there is 
chemical action; and thus, when yeast is mixed with any saccharine matter, 
a multitude of points are presented at which an active interchange is going 
on between the contents of the globules and the external fluid, and at 
which chemical action can take place. ‘The process is only accelerated by 
the presence of the ferment, or rather the fermentation is regulated, and 
the putrefactive and acetous fermentation which might otherwise be esta- 
blished, effectually controlled. Under proper conditions of temperature, 
the acetic fermentation will take place on the application of yeast, but not 
so surely or speedily as by the mycelium of the Penicillium, which is known 
under the name of the Vinegar plant, a filamentous condition instead of 
vesicular, 

“The production of yeast depends upon the extreme facility with which 
moulds adapt themselves to peculiar circumstances. The proper position of 
such moulds is upon the surface of decaying substances ; but several species 
are capable of sustaining life when completely immerged. In such a con- 
dition they cannot produce any real fruit, but they are propagated by means 
of shoots from the mycelium. Substances, which rani prove fatal to many 
other vegetables, as solutions of arsenic, opium, and many other poisonous 


BERKELEY, ON CRYPTOGAMIC BOTANY. 183 


chemical substances, do not prevent the growth of moulds. One form 
proves an intolerable nuisance in electrotyping, being developed in the 
solution of copper used in that process, and becoming itself eventually 
thoroughly electrotyped. Under such circumstances, they have the power 
of separating the metal or other noxious principle, while they avail them- 
selves of any nutritive matter with which it may be combined. ‘These fluid- 
born states of Penicillium, and other more or less allied Mycelia, are often 
regarded as Alge, but they have no affinity with those vegetable pro- 
ductions. 

“One genus of moulds was long considered as peculiarly destructive to 
living vegetable tissues, and the grape mildew, peach mildew, blane de 
rosier, &c., are all attributable to it; but it has already been shown that 
these supposed species of Oidiwm are not true moulds, but merely states of 
different species of Zrysiphe. This is, however, not the case with that class 
of moulds which belong to the old genus Botrytis, or to Corda’s genus or 
subgenus, whichever may be the more correct term, Peronospora. These 
moulds run, by means of their mycelium, amongst the loose tissue of the 
leaves, and at length protrude fertile branches through the stomates. 
Tulasne, Caspary, and others, have lately discovered that there is another 
form of fruit, with far more complicated and larger spores developed at the 
base of the fronds. The genus Artotrogus of Montagne very probably in- 
cludes such forms of fruit. But not only are they destructive to vegetable 
tissues. Where they penetrate into the intimate organs, as in the case of 
the silkworm and several other insects, they soon produce death. The 
muscardine, which is caused by Betrytis Bussiana, is capable of being pro- 
pagated by inoculation, or even without any injury of the tissues the mere 
ae of rubbing a few spores upon the body is sufficient to propagate the 

isease.” 


Our long extracts will afford a good example of the style and 
matter of the book. They also indicate the value we attach to 
its contents. However much we might be tempted to criticise 
some of Mr. Berkeley’s views, the present general notice of 
the work is not the place. Our estimate of his labours will be 
found in our most cordial and earnest recommendation of it 
to all who are engaged in the study of the lower forms of 
plants. Every one who possesses a microscope, and wishes to 
make his observations upon the innumerable forms of vege- 
table organisms by which he is surrounded available for the 
purposes of science, cannot do so more effectually than by 
making himself master of the contents of this valuable intro- 
duction to Cryptogamic Botany. 


184: 


NOTES AND CORRESPONDENCE. 


On the Structure of Amphora, a genus of Diatomacesz, and the 
Diagnosis of its Species—-When Linnzeus said that all objects 
of natural history must have a specific name, he did not mean 
a trivial name (which was not then invented), but what is called 
a short, distinctive character, otherwise it is not imperative on 
others to adopt the trivial name imposed, or recognise it in any 
way. The want of short characters (intended to place clearly 
before the mind the few essential points of difference between 
supposed new and already known forms or species) cannot be 
supplied by figures or diffuse descriptions of the entire object, 
as these leave quite in the dark the precise marks of dis- 
tinction observed by the writer, if such actually existed. In 
composing either a defining character or a detailed descrip- 
tion, it is also necessary to use the technical language of that 
science. Recently, in referrmg to Dr. Gregory’s paper on 
the Diatomacez of the Clyde, published in the last part of 
the ‘Transactions of the Royal Society of Edinburgh,’ I 
regretted that this patient observer had neglected these 
rules, and thus enveloped his whole memoir in an almost 
impenetrable cloud; thus not only precluding himself from 
claiming any right of priority of names, in the event of 
the same form being afterwards correctly characterised by 
another under a different name, but depriving the paper 
itself of its claims to be considered a scientific one. The 
same unfortunate cloud renders it difficult to understand 
what Dr. Gregory’s actual views of the structure of Am- 
phora are; although, from expressions used by him, he 
appears to enunciate the theory, that what other writers call 
a simple frustule, ought to be considered as a double one. 

To make this more intelligible to those not generally 
interested in such pursuits, I would refer to the structure 
of a diatom, as explained by Smith in his ‘Synopsis of 
British Diatomacee ;’? and recommend the mode of proving, 
by Canada balsam, whether the frustule is single or double. 
When tested in this way, what is commonly called a simple 
frustule is found to be actually so, and of one cell, so 
that Dr. Gregory’s hypothesis is untenable. The struc- 
ture of the genus Amphora appears to have been also 
slightly misunderstood by Kutzing and Smith. The real 
form of the frustule is not a spheroid, as they must have 
considered it, but rather like that of a coffee-bean, rounded 
at the back and hollowed out in front, the line connecting 


MEMORANDA. 185 


the two terminal and central nodules of each valve being the 
median line; this line and the central nodule are thus not 
marginal, as hitherto described, but exactly as in other 
diatoms in which such are found. An Amphora would thus 
chiefly differ, by the half of the valve on the one side of the 
median line being concave, while the other was convex; 
whereas, in most genera of the group the two halves of the 
valve are precisely alike. 

The form and structure of the frustule being established, 
the parts capable of affording good distinctive marks for species 
next require to be examined. All naturalists agree, that if these 
are taken from variable parts, they must be of less importance 
than if derived from those that are subject to little or no 
variation; and that no observation can be relied on, of a 
permanent kind, when taken from parts known to change 
their appearance rapidly. Thus, the zone connecting the two 
valves of a diatom, which, from being a mere line, is under- 
stood to attain the whole breadth of the frustule in the course 
of twenty-four hours, has been deservedly rejected; and 
hence it is to be feared that few or none of Dr. Gregory’s 
species of “Complex Amphore,’ which owe their peculiar 
appearance to it, will stand the test of diagnostic characters. 
As the striz, costz, or furrows, are the same on both sides of - 
the median line, and as the valve is folded, those at the back 
of the frustule must be seen through the medium of the sur- 
face nearer the eye, and crossing those belonging to it, so that 
observations on these relate entirely to the accidental position 
the frustule happens to be in. This compels one to depend 
chiefly for essential characters—Ist, on the small portion that 
is seen between the median line and the apparent outline of 
the frustule; and 2d, on the form of the frustule itself, pre- 
vious to the siliceous connecting zone commencing the process 
of self-division. 

No certain conclusions can be drawn as to what is a new 
form or species from deposits or dredgings, on account of the 
impossibility of procuring the species in an isolated state, and 
consequently of studying them independently; the same 
species putting on very different aspects, and different species 
assuming the same aspect at particular stages of self-division. 

Some species of diatoms have both an habitual and an 
accidental appearance. Thus the whole genus Pleurosigma is 
- habitually sigmoid; but P. estuarii, P. strigosum, and some 
others occasionally appear reversed or twisted, both extremi- 
ties being on the same side of the median line; P. reversum, 
fig. 105 of Dr. Gregory’s paper, will illustrate an accidental 
state; the whole supposed new genus Toxonidea of Donkin 


VOL, VI. If 


186 MEMORANDA. 


is formed of species of Plewrosigma in the same predicament. 
On the otber hand, the entire genus Cyméella is habitually 
reversed, although specimens may occur assuming accidentally 
the appearance of a Pleurosigma. 'These accidental appear- 
ances are sometimes caused by actual resupination, some- 
times from preparing to form spores, and sometimes by a 
mere change of position. 

Microscopical differences are by themselves of little im- 
portance. To see is one thing; to understand and combine 
what we see, another : the eye must be subservient to the mind. 
Every supposed new species requires to be separated from its 
allies, and then subjected toa series of careful observations 
and critical comparisons. To indicate many apparently new 
species is the work of an hour, to establish only one on a sure 
foundation is sometimes the labour of months or years. In 
microscopical natural history as much scrutiny is required to 
prove a new form to be distinct from its allies as in chemistry 
to discover a new alkaloid, or in astronomy to demonstrate 
the identity of two comets. A naturalist cannot be too 
cautious. It is better to allow diatoms to remain in the 
depths of the sea, or in their native pools, than, from imper- 
fect materials, to elevate them to the rank of distinct species, 
and encumber our catalogue with a load of new names so ill 
defined, if defined at all, that others are unable to recognise 
them; the same object can be more easily attamed by attach- 
ing them, in the mean time, to some already recorded species, 
with the specific character of which they sufficiently accord. 
In all such cases the question to be solved for the advantage 
of naturalists is not, whether the object noticed be a new 
species, but whether it has been proved such, and clearly 
characterised.—E. Watker-Arnort, Dowanhill, near Glas- 
gow. 


On the Structure of Rhabdonema and other Diatomaces 
with compound frustules.—It is with much reluctance I take 
up my pen to make the following remarks on this subject. 
During the progress of the ‘ Synopsis of British Diatomacee,’ 
by the late Professor W. Smith, a frequent correspondence was 
maintained between us, in which he constantly acknowledges 
the value of my assistance in his investigations, and promised 
to give me due credit for it in the work. 

The difficulties attendant on a clear comprehension of the 
structure of the frustule in the genera in question were con- 
siderable ; like nearly all the Diatomacez they are too minute 
for actual dissection, and whilst very opaque dry, the appear- 
ances presented in this state, so far as they could be made out, 


MEMORANDA. 187 


did not altogether harmonise readily with those in balsam. 
Professor Smith, in several letters to me (May to October, 
1853), expressed his inability to form clear conceptions of 
their structure, and begged me to pay particular attention to 
them, and try if I could make it out when engraving them, 
At one time, in the course of correspondence, he writes, ‘“ I 
do not quite understand your views ;” at another, ‘I believe 
you will prove eventually in the right.” 

The subject occupied my thoughts much, and many an 
hour of patient labour was spent in the examination of speci- 
mens. <A mounting of Rhabdonema arcuatum, burnt on talc, 
dry, at length furnished me with the long sought for key to the 
difficulty. Some of the frustules had been burst into their 
components by expansion of the contained air, the pieces, 
however, being left nearly in their relative position. From 
this the analytical figure (‘S. B. D.,’ pl. xxxviu, fig. 305+) 
was engraved, and on receipt of the proof Professor Smith 
expressed in warm terms his satisfaction with the result, and 
as we laughed over it we wondered it could ever have ap- 
peared difficult. Had the briefest acknowledgment been made 
in the ‘Synopsis’ that the discovery was mine I had been 
amply repaid the trouble and time spent over it, and should 
have been spared the very unpleasant task of writing as I 
have felt obliged to. The appearance of the second volume of 
the ‘ Synopsis’ without the promised acknowledgment pained 
me much, but the friendship that had existed between Pro- 
fessor Smith and myself prevented open mention of the in- 
justice done me, on which, as I hope at a future day to write 
on the Diatomacez, I should not have made the present 
remarks, but that the subject was mentioned in the last part 
of the ‘Journal’ in amanner which compels me to do so with- 
out further delay. The interesting specimen which furnished 
the clue to the mystery is still in my possession, and I shall 
be happy to show it to any who take an interest in the sub- 
ject. Striatella, Tabellaria, Tetracyclus, and Grammato- 
phora, after the light thus afforded, no longer presented any 
difficulties. 

It was with great satisfaction I succeeded, after much time 
and patient thought, in resolving the structure of Rhizoso- 
lenia, so neatly and pithily described by Mr. Brightwell, in 
the last part of the ‘ Journal.’ In the possession of “ annuli,” 
and in the indefinite increase of the frustule before self- 
division, this genus must undoubtedly in a natural classifica- 
tion be placed near Rhabdonema, &e. From all which, 
however, it differs in the non-possession of septa, in any of 
the several modifications now known. The extreme obliquity 


188 MEMORANDA. 


of the sides of the incomplete annuli, forming, when in 
juxtaposition, the zigzag appearance which first strikes the 
attention of an observer directed to the Rhizosoleniz, is no 
bar to the accuracy of the proposed union, for it is only a 
more developed state of a similar condition met with in 
Striatella, as will be seen by reference to the figure of the 
latter in the ‘Synopsis B. D.,’ vol. 11, pl. xxxix. 

The advantages of burning Diatomacez on tale are hardly 
yet sufficiently known or appreciated. In the more delicate 
the use of this mode of investigation is especially apparent. 
Viewed dry in this way, markings which balsam obliterates, 
are then clear and sharp, but it is especially in the making 
out of difficult points of structure, as we have just seen, and 
the exact appreciation of minute differences between allied 
species, that its value will be most felt. 

Very pretty specimens of Diatoma, Grammatophora, and 
the other forms of Diatomacee in which the frustules sepa- 
rate and cohere at alternate angles, have been obtained by 
lightly burning specimens placed on the slide, over the flame 
of a lamp. The admirable medium of Mr. Farrants pro- 
mises, however, to render the preservation of such specimens 
less difficult and uncertain. It will also, I expect, enable us 
to mount permanently specimens in conjugation, which have 
hitherto baffled every attempt made with this view, and if so 
we may confidently hope, by the diffusion of such mountings, 
to awaken further interest in this intricate subject.—TUuFFEN 
West, 8, Hemblington Cottages, Queen’s Road, Dalston. 


On the History of Arachnoidiscus—In reply to your note 
of this date I can say little beyond the fact that, on March 
17th, 1847 (just eleven years last Wednesday), I read a short 
unscientific notice “On the occurrence of Arachnoidiscus 
on an edible fucus from Japan,” at the end of which, on a 
question put by our friend John Quekett, I said, “ From 
the circumstance of these discs presenting a reticulated 
appearance, similar to the webs of some species of spiders, I 
propose to call the genus Arachnoidiscus, and the species 
above mentioned Japonicus. My notice did not give a 
scientific description of the genus intelligible to any one, and 
therefore, as I have since learned, I have no claim to it. It 
might have been otherwise had any one kindly suggested to 
my greenness the right course to render my notice of a new 
thing perfect. 

Dr. Walker-Arnott lately wrote to me on the subject at 
the suggestion of Dr. Harvey, who knew what I had done, 
and to whom I was indebted for species from Mauritius. He 


MEMORANDA. 189 


wished to know who was the author of the genus, and where 
Bailey’s description was to be found, &c.; and I sent him a 
copy of my notice. Bailey gets the credit, perhaps properly 
according to rule, but I cannot help feeling waiving my 
having sug egested the name—that Shadbolt has the prior 
claim, as he read a paper on the subject, November 14th, 
1849 (‘Trans. Micr. Soc.,’ vol. ii, p. 49). I have an im- 
pression that the first specimens Bailey ever had were mine, 
forwarded to him by Mr. Marshall, who I am sure would 
have named to him the whole history. A matter of this kind 
is so trivial and insignificant that it is not worth discussion 
except on principle, and I cannot help thinking that it would 
be well if men advanced in scientific knowledge, and holding 
a deservedly high position im consequence, would encourage 
the smaller fry, by giving them every credit for their small 
but earnest labours and good intentions in the common 
cause. 

I suspect Mr. Tuffen West has done more with this genus 
than any other man in this country. 

At the time I wrote my notice all the Diatomacez were 
generally presumed to be animal, their anatomical structure 
was little known and seldom was any given, the name being 
supposed to convey a tolerably correct idea of the object.— 
Hy. Dranz, Clapham Common. 


Physical Influences exerted by living Organic and Inorganic 
Membranes upon Chemical Substances.—In a paper published 
in the ‘American Journal of the Medical Sciences,’ by Mr. 
Joseph Jones, he gives the following results of a series of 
experiments upon living animals and plants. 

“1. Cell-walls, like animal membranes, exert a physical 
influence upon the chemical substances held in solution pass- 
ing through them. This physical influence is capable of 
altermg the arrangement of the molecules of the precipitate 
formed within the cells, so that the precipitate which under 
ordinary circumstances consists of irregular granules, under 
the influence of the endosmotic action assumes a regular 
crystalline form. 

“2. The cells of different vegetables, like different animal 
membranes, change in different manners the arrangement 
of the molecules of the same substance. 

“It may yet be demonstrated, by experiment, that cells in 
the same plant, having different offices, elaborating different 
products, exert a different physical influence upon the same 
chemical substance. Or, in other words, the crystalline 
deposit of the same substance will vary in physical properties 
with different cells.” 


190 


PROCEEDINGS OF SOCIETIES. 


GrotocicaL Society, December 2d, 1857. 


On some peculiarities in the Microscopical Structure of 
Crystals, applicable to the determination of the Aqueous or 
Igneous Origin of Minerals and Rocks. By H. C. Sorsy, 
Ksq., F.R.S., F.G.S. 


In this paper the author showed that when artificial crys- 
tals are examined with the microscope, it is seen that they 
have often caught up and inclosed within their solid substance 
portions of the material surrounding them at the time when 
they were being formed. Thus, if they are produced by 
sublimation, small portions of air or vapour are caught up, so 
as to form apparently empty cavities ; or, if they are deposited 
from solution in water, small quantities of water are inclosed, 
so as to form fluid-cavities. In a similar manner, if crystals 
are formed from a state of igneous fusion, erystallizing out 
from a fused-stone solvent, portions of this fused stone be- 
come entangled, which, on cooling, remain in a glassy condi- 
tion, or become stony, so as to produce what may be called 
glass- or stone-cavities. All these kinds of cavities can readily 
be seen with suitable magnifying powers, and distinguished 
from each other by various definite peculiarities. 

From these and other facts, the following conclusions were 
deduced : 

1. Crystals containing only cavities with water were formed 
from solution. 

2. Crystals contaiming only stone- or glass-cavities were 
formed from a state of igneous fusion. 

3. Crystals containing both water- and stone- or glass- 
cavities were formed, under great pressure, by the combined 
influence of highly heated water and melted rock. 

4. That the relative amount of water present in the cavities 
may, in some cases, be employed to deduce the temperature 
at which the crystals were formed, since the accompanying 
vacuity is due to the contraction of the fluid on cooling. 

5. Crystals containing only empty cavities were formed by 
sublimation, unless the cavities are fluid-cavities that have 
lost their fluid, or are bubbles of gas given off from a sub- 
stance which was fused. 


PROCEEDINGS OF SOCINTIES. - 191 


6. Crystals contaiming few cavities were formed slowly, in 
comparison with those of the same material that contain 
many. 

7. Crystals that contain no cavities were formed very 
slowly, or by the cooling from fusion of a pure, homogeneous 
substance. 

Applying these general principles to the study of natural 
crystalline minerals and rocks, it was shown that the fluid- 
cavities m rock-salt—in the calcareous spar of modern tufa- 
ceous deposits, of veins, and of ordinary limestone—and in 
the gypsum of gypseous marls, indicate that these minerals 
were formed by deposition from solution in water at a tem- 
perature not materially different from the ordinary. The 
same conclusions apply to a number of other minerals in 
veins in various rocks, and to many zeolites. The constituent 
minerals of mica-schist and the associated rocks contain 
many fluid cavities, indicating that they were metamorphosed 
by the action of heated water, and not by mere dry heat and 
partial fusion. 

The structure of the minerals in erupted lava proves that 
they were deposited from a mass in the state of igneous 
fusion like the crystals in the slags of furnaces; but, in some 
of those found in blocks ejected from volcanos (for example, 
in nepheline and meionite), there are, besides stone- and 
glass-cavities, many containing water, the relative amount of 
which indicates that they were formed, under great pressure, 
at a dull red heat, when both liquid water and melted rock 
were present. The fluid cavities in these aqueo-igneous 
minerals very generally contain minute crystals, as if they 
had been deposited on cooling from solution in the highly 
heated water. The minerals in trappean rocks have also 
such a structure as proves them to be of genuine igneous 
origin, but they have been much altered by the subsequent 
action of water, and many minerals formed in the minute 
cavities by deposition from solution in water. 

The quartz of quartz-veins has a structure proving that it 
has been rapidly deposited from solution in water; and in 
some instances the relative amount of water in the fluid- 
cavities indicates that the heat was considerable. In one 
good case the temperature thus deduced was 165° C. (829° F.) ; 
and apparently, when the heat was still greater, mica and 
tinstone were deposited, and in some cases probably even 
felspar. There is, then, as has been argued by M. Elie de 
Beaumont, a gradual passage from quartz-veins to those of 
granite, and to granite itself; and there is no such distinct 
line of division between them as might be expected if one was 


192 PROCEEDINGS OF SOCIETIES. 


a deposit from water, and the other a rock that had been in 
such a state of pure igneous fusion as the slags of our 
furnaces or the erupted lavas. When the constituent 
minerals of solid granite, far from contact with the stratified 
rocks, are examined, it is seen that they also contain fluid- 
cavities. This is especially the case with the quartz of coarse- 
grained, highly quartzose granites, in which there are so 
many, that the proportion of a thousand millions in a cubic 
inch is not at all unusual; and the inclosed water constitutes 
from one to two per cent. of the volume of the quartz. 
However, besides these fluid cavities, the felspar and quartz 
contain excellent stone cavities, precisely analogous to those 
in the crystals of slag, or erupted lavas; and thus the 
characteristic structure of granite is seen to be the same as 
that of those minerals formed under aqueo-igneous con- 
ditions in the blocks which are ejected from modern 
voleanos; and the very common occurrence of minute 
crystals inside the fluid-cavities still further strengthens this 
analogy. 

The conclusion to which these facts appear to lead, is that 
granite is not a simple igneous rock, like a furnace-slag, or 
erupted lava, but is rather an aqueo-igneous rock, produced 
by the combined influence of liquid water and igneous fusion, 
under similar physical conditions to those existing far below 
the surface at the base of modern volcanos. 

These deductions of the author, therefore, strongly confirm 
the views of Scrope, Scheerer, and Elie de Beaumont; and 
he agrees with them in considering it probable that the 
presence of the water during the consolidation of the granite 
was an instrumental, if not the actual cause of the difference 
between granite and erupted trachytic rocks. 


MicroscopicaL Socigty, January 13th, 1857. 
Grorce SHapsott, Esq., President, in the chair. 


W.S. Gibbons, Esq., Melbourne, South Australia; Henry 
Blanchard, Esq., 5, Upper Bedford Place ; and T. Maltwood, 
Esq., 130, Fenchurch Street, were balloted for, and duly 
elected members of the Society. 

The following papers were read— 

“ On a New Object-finder,” by T. Maltwood, Esq. (‘ Trans.,’ 

. 59.) 
. A discussion followed, in which Mr. W. Histor said— 
I beg to remark that I have for some time been making 
experiments, having for their object the production of mi- 
nutely divided scales by photography, such scales to be used 


PROCEEDINGS OF SOCIETIES. 193 


as micrometers for the microscope, intending eventually to 
bring the subject before this Society. I employ for the pur- 
pose an apparatus of my own, which has been described in 
the ‘ Photographic Journal,’ as adapted to the production of 
micro-photographs generally. I think that the method of 
printing these scales, recommended in the paper just read, 
will not give sufficiently fine results for the purpose proposed, 
namely, the construction of a photographed scale whereby 
the distance of some part of a slide may be measured from a 
fixed point. I very much prefer wet collodion for these 
minute lines, and reduce the scale from a large one by two 
operations—one in the camera, to obtain a negative, and 
another in the apparatus just mentioned, using a microscopic 
object-glass as the reducing lens. The beautifully perfect 
minute pictures which have already been produced on wet col- 
-lodion prove that we can thus get all we want in sharpness and 
distinctness. With regard to this plan for the production of di- 
vided scales by photography, I am disposed to think that it has 
many advantages. One very important one is that any error 
in the large scale will be reduced in direct proportion to the 
reduction of the whole. Thus, an original error of, say, the 
50th of an inch, reduced 100 times, becomes the 50,000th of 
aninch. For use on the stage, however, these photographed 
scales, whether as finders or micrometers, would not be good 
under high powers, inasmuch as the silver deposit would be 
so much magnified as to separate its particles. Measuring by 
the stage micrometer is scarcely possible except with a low 
power, but is perfectly easy when the divided scale is placed 
in the eyepiece, in which position this objection to a photo- 
graph would scarcely apply. 

Mr. Jackson remarked that if the squares were only the 
100th of an inch on the side, it might be difficult to print 
the figures with sufficient distinctness from a negative of the 
same size by contact ; and suggested that a negative of three 
or four inches square should first be taken, and the finders 
should be reduced to the exact size and printed on wet collo- 
dion by means of a small fixed camera, much in the same 
manner as he had adopted for printing the microscopic por- 
traits. He also recommended that the figures should be 
written in what has been termed Egyptian type, that is, with 
the up strokes and down of the same thickness ; and he ex- 
hibited the photograph of a card, taken in the above manner, 
in which such letters were quite plain when reduced to 
1000th of an inch in height. 

“On the Miliolitide of the East Indian Seas,” by W. K. 
Parker, Esq. (‘Trans.,’ p. 53.) 


194, PROCKEDINGS OF SOCIETIES. 


February 10th, 1858. 


ANNIVERSARY MEETING. 
Grorce Snapzott, Esq., President, in the chair. 


The minutes of the preceding meeting were read and con- 
firmed. 

Reports from the Council and Auditors of the Treasurer’s 
accounts were read and ordered to be received and printed. 

The President delivered an address. (‘Trans.,’ p. 65.) 

It was resolved that the President’s address be received, 
printed, and circulated in the usual manner with the pre- 
ceding reports. 

J. Bolton, Esq., 6, Regent’s Park Terrace ; George Guyon, 
Esq., Richmond; and F. Brodie, Esq., Eastbourne, were 
balloted for, and duly elected members of the Society. 

The Society then proceeded to ballot for officers and four 
members of Council for the ensuing year. (‘Trans.,’ p. 77.) 


March 17th, 1858. 
Dr. Lankerster, President, in the chair. 


W. Harkness, Esq., London Hospital; James Temple, Esq., 
Bruntsfield House, Finchley Road; Charles Tyler, Esq., 23, 
Holloway Road; Dr. Woodman, Courtenay Terrace, Kings- 
land; and Dr. Dempsey, 145, Goswell Street, were balloted 
for, and duly elected members of the Society. 


A paper on the luminous organs of the Glow-worm, by 
Professor Kolliker, was read. 


ORIGINAL COMMUNICATIONS. 


Norrs on Aracunorpiscus, Pxievrosigma, AMPHIPRORA, 
Eunotia, and Ampnora. By G. A. Watkrer-Arnott, 
{ih 


ARACHNOIDIscUS.—Since my observations on this genus 
were published in the last number of this Journal, at p. 160, 
my attention has been called to the ‘Annals and Mag. of 
Nat. Hist.,’ for 1848, vol. 1, p. 393, in which there is a 
translation of Ehrenberg’s paper on Hemipiychus. I am 
likewise informed by another correspondent that it was 
published in the ‘ Berlin Proceedings’ for 1848, p.7. I have 
not access to the original, but from what is said in the trans- 
lation, it is clear that Ehrenberg got his specimens from Mr. 
Topping, of London; and as it is generally well understood 
that the Arachnoidiscus was obtained by Mr. Topping from 
Ichaboe guano, the suspicion I threw out is verified. Whe- 
ther it was certainly from Patagonia, that the Danish vessel 
Waldemar (spoken of by Ehrenberg) brought its cargo of 
guano, I know not ; Ehrenberg understood this, and his infor- 
mation may have been correct, although doubts arise from 
the following considerations. From that guano Ehrenberg 
obtained the diatom which he has called Hntopyla australis, 
for which he quotes as a synonym his former Swriredla (?) 
australis ; now my impression, from studying attentively his 
generic character, is that the Entopyla australis is the same as 
my Eupleuria (or Gephyria) incurvata, which is from Ichaboe 
and Saldanha Bay guano; while his Sur. australis, from the 
Falkland Islands, and not, I believe, from guano at all, is 
probably my fu. ocellata. But it is almost impossible to 
determine this point without seeing perfect specimens. 

I may add, that I am now informed by M. De Brebisson, 
that the single frustule of Arachnoidiscus, which he detected on 
Sphacellaria olivacea, sent him by Myr. Ralfs, and which is the 
authority for that genus being British, belongs to A. ornatus,* 
and is therefore the same as from Ichaboe and the Cape. As 
the species of this genus, like other diatoms, are gregarious, the 
discovery of only one frustule seems to indicate some error 
about its title to a place in the catalogue of British genera. 


* Threnberg’s specific appellation was orvatus ; such (and not formosus) 
is the name which I obviously intended to give to the second Arachuoidiscus 
at page 162, about the middie. This readers will please to correct. 

VOL. VI. Q 


196 WALKER-ARNOTT, ON ARACHNOIDISCUS, ETC. 


Prevrosicma.—I find from some correspondents that the 
remarks I made in the last number of the ‘ Microsc. Journ.,’ 
p- 164, have conveyed more than one erroneous impression. 
I had no intention to find fault with any gentlemen supply- 
ing Dr. Donkin with the information they gave; they got 
the information from friends in a perfectly legitimate way, 
and furnished it as legitimately, although from not coming 
directly from myself, it was partly meorrect and partly mis- 
understood. Had Dr. D. applied to me, I would have at 
once explained to him how the diatom in question came to 
be referred to Amphiprora; and then, I have no doubt, the 
paragraph at p. 33, which appeared to me uncourteous, would 
not have been written. Mere MS. trivial names are, by 
common consent, referred to every day; but unless the 
giver has himself published his reasons for such names, 
whether generic or specific, they are quoted without note 
or comment, and solely as provisional ones or synonyms ; 
a departure from this would imply a right to give to the 
public information not imtended for it, and which was ob- 
tained privately. This right, however, happily does not 
exist ;* for if it did, it would destroy all friendly intercourse 
by letters. 

The synonyms I gave were less with the intention to criti- 
cise Dr. Donkin’s new forms, as to show that others had 
been engaged also on several of the same; and that in the 
present dislocated state of this branch of science, (now that 
we have lost Professor Smith as a common bond of connec- 
tion,) it is desirable that before any one publishes new or 
supposed new British species, he should make extensive 
inquiries among diatom collectors, so as to discover if the 
same have not previously occurred to them, but perhaps under 
a slightly different form, and if the difference cannot be 
explained by extrinsic causes. By submitting the diagnosis, 
and taking the opinions of several, naturalists as well as 
microscopists, students of cause as well as those of effect, a 
person is more likely to come to a correct conclusion than 
by trusting to oneself, or consulting those only who are likely 
to agree with him; at all events, the species is thus amply 
discussed before publication, and not left to after-criticism. 
Some of the synonyms I adduced (at p. 165) are not pub- 
lished, and although the species have been long known and 
in many of our cabinets, and although probably Dr. Donkin 
would have adopted such MS. names, so far as they were 


* See, in regard to private correspondence, ‘Notes and Queries,’ 2d 
series, vol. v, pp. 47, 76. 


WALKER-ARNOTT, ON ARACHNOIDISCUS, ETC. 197 


eligible, had he been aware of them, still those names which 
he has given, that are accompanied by a clear diagnosis, have 
now the right of priority. 

In my remarks I mentioned that the figure of the F.V. of 
Pleurosigma lanceolatum could not belong to it ; I have since 
received a specimen of this through the kindness of Dr. D., 
and to me the striz appear horizontal, while those of P. lan- 
ceolatum (S.V.) are diagonal. As to what P. lanceolatum 
itself is, different observers are entitled to hold different 
opinions; Mr. Roper’s P. transversale (3 is, I believe, allowed 
by all to be identical; and if I do not coincide with him, it 
is solely because there seems to me more points of dissimi- 
larity from, than of resemblance to, P. transversale. Taking 
into consideration that P. estuarii is “frequently direct,” 
and that what Professor Smith would have called the “ type” 
of that species has the ends “ somewhat produced ” or api- 
culate, and also the striation, I am almost satisfied that 
P. lanceolatum is a form of it peculiar to clean sand; but 
as yet neither P. danceolatum* nor the apiculate state of 
P. estuarii have occurred, so far as I know, sufficiently 
isolated to allow of any positive deduction being drawn. 
What is considered the non-apiculate state of P. estuarii, 
has been got copiously in some gatherings; but that chiefly 
differs from a small form of P. angulatum by the slightly 
more difficult striz, and may be considered one of a nume- 
rous group of intermediate diatoms, none of which can be 
referred with certainty to any species as at present (too 
stringently) limited, and yet are destitute of any marked 
peculiarity to permit of a separation,—a group that will 
ultimately cause the union of several “ fest species’ of that 
genus. The P. lanceolatum of Dr. Donkin must not be 
confounded with Mr. Norman’s species of the same name, 
(noticed, but not defined, in the ‘Ann. of Nat. Hist.’ for 
1857, vol. xx, p. 159); this last does not seem to me distinct 
from small forms of P. strigosum, Sm.+ I referred P. 

* Thave the same form from Cumbrae in the Clyde, accompanied by Tozxo- 
nidea insignis and Gregoriana, and Pleur. angulatum. If P. lanceolutum be 
distinct from P. estuariz, it is to it that Zor. insignis may be referred; but I 
cannot indicate any marks by which the anomalous state of each is to be re- 
cognised, except by the normal form which accompanies it. Zor. Gregoriana 
I refer to the sand form of Pl. angulatum. 

+ I may here mention that “ P. s¢rigosum” seems to have been adopted 
by Smith on the supposition that the Hull Wav. strigosa, of Harrison, was 
the same; this, however, I have ascertained, is not the case. WJ. strigosa 
of Harrison and Sollitt (‘ Micr. Journ.,’ ii, p. 62), is P. angulatum, Sm.; 
while their V. angulata is P. quadratum, Sm. ; their N. lineata is P. elonga- 
tum, Sm. It is not, however, improbable that these and some others form 
a single species. 


198 WALKER-ARNOTT, ON ARACHNOIDISCUS, ETC. 


Wansbeckii, Donk., to Amphiprora Ralfsii; the examination 
of a specimen from Dr. Donkin satisfies me that I was 
wrong, and that it is a true Pleurosigma, and the same 
which Smith has called P. Balticum 8; I learn from Mr. 
Roper that his opinion quite coincides with my own. This 
also is the same which is called Navicula scalprum by Kutzing, 
as far at least as regards the form found by De Brébisson 
(see ‘ Kutz. Sp. Alg.,’ p. 85); and it may be the same as 
that figured by Kutzing (Bac. tab. 30, fig. 13), from Trinidad, 
and since called by him N. Scalpellum, but it scarcely agrees 
with the figure of N. scalprum given by Gaillon and Turpin 
(who first gave the name), in the ‘ Mem. du Mus.,’ xv, t. 10, 
fig. 3, and which figure is copied by Kutzing (Bae. tab. 4, 
fig. 25), and appears rather to indicate P. Hippocampus, 
Sm. In P. Balticum, B and y of Smith, the strie are as 
numerous as 64 or 65 in ‘001; and from notes before me 
I find that some others raise that number to 85; this 
creates a doubt if these two varieties ought not to be 
separated from a species which has only about 38. I believe 
that the usual state of P. Balticum is scarcely or not at all 
found at Hull, whilst the var. y occurs copiously at Hessle, 
and sparingly in several other places in that neighbour- 
hood; this, however, by itself, affords no valid reason for 
the separation, any more than that the mixture of all the 
three would prove them only to be varieties of the same 
species. 


AmpuHiprora.—The verbal distinction between this genus 
and its cognates Navicula and Pleurosigma is so slight as 
to be easily passed over. It is unnecessary to refer to 
Kutzing’s generic character of Amphiprora, which is obtained 
from the Front View only, while that of Navicula (including 
Pleurosigma) is derived from the Side View; “the so-called 
wings (a/@), or projections (as has been remarked by Mene- 
ghini), belong to the secondary surfaces (S. V.) and consti- 
tute the only distinctive character of the Amphiprore.” B 
comparing Smith’s analytical table at p. 9 of vol. i. of his 
‘Synopsis of Br. Diat.,’ with the characters given at pp. 43, 46, 
and 61, it will be seen that his views are that in Amphiprora 
the F. V. of the frustule and valves is deeply constricted late- 
rally, while the valves, or S. V., are furnished at the median line 
with a ridge or keel; in the two others, on the other hand, 
the F. V. is without a conspicuous constriction, and the valve 
is plane or convex merely, and the median line destitute of 
a keel. There is thus a double character, and when the one 
is not very decided the other may be taken asa guide. I 


WALKER-ARNOTT, ON ARACHNOIDISCUS, ETC. 199 


believe that Smith’s views are now almost universally 
adopted; at the same time there are some cases which re- 
quire careful consideration. 

Pleurosigma is said to have sigmoid valves, that is, flat, but 
bent laterally in the same plane, at the one end, in a differ- 
ent direction from what they are at the other. In Navicula 
the opposite character is not given, but is implied. In XN. 
Jenneri and N. convexa the valves, at first sight, appear to be 
sigmoid; but the cause of this is easily understood by 
examining the F. V.; from it, it will be seen that the eutire 
frustule is not simply bent to the right or left, but has a 
slight spiral twist ; so that when the valves are separated they 
do not lie flat, and the result is the apparent sigmoid median 
line: had the valve not been twisted, the median line would 
have been perfectly straight and central. In Pleurosigma 
I have seen no instance in which the living frustule is 
twisted ;* “the F. V. is either of a linear, or linear-lan- 
ceolate, form” (Sm.), and the 8. V. is sigmoid, with the 
median line nearly equidistant from the two sides; but after 
the valves are detached from the connecting zone they often 
become slightly twisted, and as they cannot then present a 
flat surface to the eye, the median line appears to approach 
nearer to the one margin than to the other. How far the 
amount of this mequality can be relied on for the distinction 
of species is doubtful; P. decorum is principally separated by 
Smith from P. formosum by such an appearance. I am not 
aware that this twist has been seen except in those species 
which have oblique striz, and it may be dependent on that 
structure. 

In Amphiprora the median line in the entire frustule is 
usually straight, and when not so this arises from the torsion 
of the frustule; in A. alata and A. paludosa the frustule 
presents both appearances, as shown at fig. 124 6, and 0’, 
and fig. 260 6, and 0’, of ‘Smith’s Diat.2. I have not, how- 
ever, myself detected the twisted form in these while the 
diatom was alive, and it is often not so even after being 
dried, or maceration in weak acid. When the valves are 
separated from the connecting zone, their tendency to assume 
the spiral form is much more striking, as exhibited by Smith 


* T have not myself the F.V. observed of the living frustule of any 
of the anomalous or distorted states which form the genus Zoxonidea of 
Donkin ; of these states I have seen five, one I would refer to Pleus. estuarii, 
a second, if distinct, to P. danceolatum, a third to P. transversale, a fourth 
to P. angulatum, and the fifth to P. strigosum. The third of these I have 
detected lately, but of it only one frustule; the others I have already 
noticed (p. 165). 


200 WALKER-ARNOTT, ON ARACHNOIDISCUS, ETC. 


in his fig. 124 a, and a’; when this occurs the median line, 
formerly straight, becomes also spirally twisted.* 

The genus Amphiprora, as appears to me, may be readily 
distinguished from Pleurosigma by attending to these con- 
siderations. The extreme thinness of the connecting zone in 
the latter renders it almost impossible to obtain a F. V., 
unless in fluid agitated by a drop of spirit of wine, while in 
the former the F. V. is readily detected, the connecting zone 
being of considerable breadth; in Pleurosigma the F. VY. is 
less in breadth than the breadth of the valve, while in Amphi- 
prora it is generally the reverse. 

I have not seen any Amphiprora with the principal or 
coarser striz oblique, although, from the facility of torsion 
in its valves such instances may occur. But as all diatoms, 
with striz composed of dots, have four rows of striz, two 
diagonal, one horizontal, and one longitudinal; and as the 
visibility of each depends, when delicate, on the position the 
valve presents to the illuminating oblique pencil of light, 
the closer or more difficult striz are sometimes seen when 
the others are not, and thus may be occasionally mistaken 
for the predominating or coarser ones, which alone are made 
use of in specific characters. I may here remark that when 
the dots are placed so as to form rectangles, the transverse 
and longitudinal lines are always the most remote, and there- 
fore predominate; and it is generally supposed that, when 
the dots are quincuncial, the diagonal lines are always most 
apparent ; but this conclusion is not correct, for when the 
diagonal lines make, with the transverse, an angle greater 
than 60°, the transverse rows are more remote than the 
diagonal, and when the angle is less than 30°, the longitudi- 
nal rows are the more remote and easily detected. In the 
quincuncial structure, therefore, the diagonal lines predomi- 
nate only when the angle of inclination is more than 30° and 
less than 60°; but the transverse and longitudinal cannot 
both preponderate in the same species. 

To distinguish Navicula from those species of Amphiprora 
which have the frustule straight and no ale, is considerably 
more difficult, and I doubt if there be any characters more 
readily available than those mentioned by Smith, viz., the con- 

* The facility of twisting and the amount seem to depend on the smaller 
or greater quantity of silex assimilated by the frustule; and this again, in 
all diatoms, varies in the same species according to the vigour of its growth, 
arising from locality, season of the year, and other incidental causes. Our 
whole knowledge of these beings is as yet in an embryo state, and will be 
best promoted by extensive morphological observations on species about 


which all are agreed ; till then the limiting characters of species, and the 
species themselves, must be very unsatisfactory. 


WALKER-ARNOTY, ON ARACHNOIDISCUS, ETC. 201 


stricted frustule and carinate valve or median line; the first 
of these is not to be much relied on, as it is exhibited slightly 
in some species of Navicula, while it is observed only in a 
modified manner in A. vitrea. In this species, and also in 
A, elegans, there seem to be frequently four valves to the 
frustule ; I have seen the same structure in Schizonema cruci- 
gerum, Pinnularia major, lata, alpina, and some others, but 
it is accidental and not characteristic of such species. 

Dr. Gregory, in his paper on ‘ Clyde Diatoms,’ introduces 
into the descriptions of some of his forms, a notice of a “ plate” 
which is said to be above the valves; he does not seem 
to consider its occurrence as universal in the genus, but 
characteristic of certain species only. How these plates 
are formed or attached I do not understand. I am not 
aware that they have been seen separated from the valves, 
and if a peculiarity of structure of the valves, they ought to 
be traced in these. Although, however, I have attempted to 
model in clay or putty a frustule with the valves as figured 
and described, connected by a zone, I have not succeeded in 
constructing anything like these plates. That there is such an 
appearance is unquestionable, so that a suspicion arises that 
such plates do not lie above the valves, and indeed have no 
actual existence, but that the whole arises from our seeing 
the margin, or the surface outline of the valve, through the 
medium of part of the frustule. If proved to be actually 
external and above the valves, or to be caused by any 
other difference of structure from what is usual in the genus, 
its importance as a specific distinction will be readily allowed. 

I exclude, at present, from the genus the curious and perfectly 
distinct A. complexa of Dr. Gregory. As the slices are not per- 
forated, they cannot be annuli, such as occur in Rhabdonema ; 
and if entire lamina of the connecting zone,* an obscure affinity 
with Rhipidophora would be established. The true structure of 
this diatom, and therefore its genus, is however quite uncertain. 


* In various species, particularly marine ones, of different genera of 
diatoms, as Navieula, Amphora, Amphiprora, and Schizonema, the connecting 
zone exhibits frequently a lamellar structure, the number and appearance 
of the lamellze varying much in the same species according to circumstances. 
Navicula Libellus of Dr. Gregory, on that account, seems to be the well-known 
and not uncommon state of Schizonema Grevillii. When these lamelle are 
perfect, the frustule is necessarily divided by them into two cells, a proof 
that it is then undergoing self-division; but the cause of this appearance, 
or why it is not to be detected at all times in the same species, is unknown 
to me. Several, if not all, of Dr. Gregory’s group of *‘ complex Amphoras” 
are in this predicament ; at least in these the lamelle are not described and 
figured as annular or with a perforation, as would be were the zone not in 
the variable or transition stage, and thus unsuited for specific distinctions. 


202 WALKER-ARNOTT, ON ARACHNOIDISCUS, ETC. 


Evunorra.—To define this genus appears to have caused 
Professor Smith some trouble; at first his intention seems to 
have been chiefly to distinguish it from Epithemia, with which 
it was combined by Ehrenberg; but in his second volume, 
under Himantidium, he proposes to introduce the radiating 
strize as a character. One of his species (£. arcus) may be 
left out of consideration, as this grows attached to small 
algze, by the end, by means of a “ cushion-like pedicel,” as in 
Synedra, to which genus it belongs; indeed, when I met with 
it,im that state, near Brodick, in Arran (July 1854), it was 
so closely intermingled with S. pulchella and S. gracilis that 
I then felt disposed to consider it a deformity of one of these. 
In all the genuine species of Hunotia which I have examined 
previous to or after a very slight maceration in acid, I find 
the portion called the valve by Smith to be more composite 
than can be inferred from his figures, each being made up of 
parallel slices or lamina, easily observed in the F. V.; and I 
have been so unfortunate as never to see the connecting zone 
as represented: indeed, had Mr. West’s accuracy not been 
beyond suspicion, I should say, as the result of my own 
observations on recent gatherings, that this broad zone did 
not exist, and that the supposed single valve was composed 
of several valves, each separated by a very slender and almost 
invisible zone. I therefore, at present, consider each sup- 
posed valve to be formed of a series of frustules, and that the 
connecting zone figured in Smith’s work is some accidental 
enlargement of one of the slender connecting zones. Be 
that as it may, the divisibility of the supposed valve into 
several is perfectly different from what has been seen in the 
genus Himantidium, where the valves are incapable of dividing 
and are separated by a siliceous zone of considerable breadth. 
This structure at once enables us to remove &. gracilis, Sm., 
(although the frustules are often solitary) to Himantidium, 
under which genus the small state of it had been previously 
described by Kutzing as H. exiguum of De Brébisson. 


Ampnora.—Some friends having expressed a wish that I 
should explain my views of the structure of the genus 
Amphora more fully than given at p. 184 of this volume of 
the ‘ Micr. Journ.,’ I subjoin the following extract from the 
paper as originally prepared. 

Kutzing’s ideas of the structure of this genus are not 
very clear. If we compare his description of it with that of 
Navicula, and swppose that in the former he has mistaken the 
Front for the Side view of the frustule, the characters of both 
will scarcely differ, and his views would thus be much the same 


WALKER-ARNOTT, ON ARACHNOIDISCUS, ETC. 203 


as my own, which, indeed, occurred to me from supposing 
Kutzing’s observations to have been misprinted. If, on the 
other hand, he has not inverted these, he must have looked 
on the frustule as a hollow spheroid, and that planes passing 
longitudinally through the central nodules and the eye, 
would cut off the valves. Smith has obviously understood 
Kutzing in this sense, and although some expressions and 
his figures would seem to indicate that he was not altogether 
satisfied on the subject, he adapted his generic character to 
it, and described each valve with the central nodule mar- 
ginal; in this way the whole portion between the median 
lines must be considered as the connecting zone. But that 
such cannot be its real structure is obvious: Ist, from there 
being a deep groove or hollow in front: 2nd, from the sides of 
this groove, nearly up to the median line, being striated 
precisely as on the other side: 3rd, from the median line, 
forming a ridge; the first of these is best seen by putting the 
entire frustule, before being macerated, into balsam; the two 
last require us to examine it obliquely when not in balsam. 
The anterior margin of the valves, where they are attached 
to the connecting membrane, is thus not close to or on a 
level with the nodule, but considerably farther from the eye, 
closer to and more directly above the posterior margin. 

The form of the frustule of Amphora may thus be com- 
pared to that of a coffee-bean, rounded on the back and 
hollowed out in front, a transverse section being somewhat 
reniform or lunate. If we take two circular pieces of paper, 
gum them together by their edges, and mark this disk on the 
margin, with two dots of ink at the extremities of a diameter 
which is at right angles to another which may be supposed 
the axis or line of self-division ; the dots will represent the 
central nodules, and the edge of the disk the median line; a 
diatom lke that would only differ from the genus Navicula by 
the valves being much folded or compressed, while in Navicula 
they are usually nearly flat or depressed. If we now bend 
up the sides of the disk, so that the central nodules approach 
each other, this will in some degree represent an Amphora, 
the only difference being that in the disk the curves of both 
surfaces are almost parallel, the one concave, the other con- 
vex, while in Amphora the anterior or concave one is usually 
smaller than and of a different kind from the posterior. In 
Amphora, then, the median line, as that ought to be called 
which connects the central with the subterminal nodules, 
although apparently marginal, is similar to what is observed 
in other Diatomacez in which nodules exist; indeed, this 
genus only differs by the portion of each valve on the one 


204 WALKER-ARNOTT, ON ARACHNOIDISCUS, ETC. 


side of the central nodule being smaller and differently 
curved from that on the other, whereas, in most genera of 
the group, these two portions are alike. 

The incurvation of the valves is at its minimum when they 
are in the incipient state, at its maximum when the frustules 
have separated after self-division. The proximate cause is 
the contraction of that half of the valves which in the disk of 
paper is next the eye, and its consequent thickening, for the 
quantity of silex is probably the same on both sides; but the 
cause of the contraction I cannot explain. By this bending 
in of the valves the central nodule, which was apparently 
marginal, now assumes a position sometimes nearly vertical 
to the line of fission, but sometimes reaching to only one 
fourth of that distance. The maximum incurvation and also 
the projection of the median line on the plane of the field of 
view (a line of double curvature) vary in the same species, 
although generally within certain limits. The true form of 
the valve would be nearly got by completing the apparent 
outline by the addition of the incurved part; but the apparent 
outline of the frustule itself, at the maximum incurvation of 
the valves, is found to be more easily observed and con- 
venient for description ; and to this, there is no objection, if 
those frustules only be used in which the connecting mem- 
brane is at its minimum breadth. The strize on the valve are 
precisely alike on each side of the median line, but from 
some being seen through the medium of the valves, and 
others presenting themselves directly to the eye, the former 
appear faint and hazy; the latter, between the median 
line and the outline, are therefore alone referred to, in 
their definitions, by the more eminent diatomists. From 
the minuteness of the object, its inequality of surface, the 
necessity of using high powers and these with a large angle 
of aperture, it is impossible to bring all the parts into view, 
without altering the focus, or to give a perfectly accurate 
representation of the structure except by models. 

The portion separating the two valves, or the connecting 
zone, varies much in all diatoms, but more so in Amphora than 
in most other genera. At first it is narrow, then it becomes 
broader and broader, but is in most species striated very 
differently from the valves, if striated at all.* The new or 
intermediate valves, which it projects, are at first destitute of 


* The circumstance of the structure of the connecting zone being the 
same, or very different from that of the valves, indicates two groups or 
sections of the genus. As this is quite independent of self-division, it is 
of more importance than the splitting of the connecting zone into several 
plates, at least until the cause of this be ascertained. 


WALKER-ARNOTT, ON ARACHNOIDISCUS, ETC, 205 


silex and imperfectly seen, then they become more and more 
conspicuous and siliceous, rapidly altermg in shape and_posi- 
tion ; the primary valves also alter in position, but not im 
form. The central nodules of the two new valves appear 
now at the back, nearly where the connecting zone formerly 
was, while the back of each half of the double frustule is re- 
moved to the side, or is placed right and left of the spectator’s 
eye, instead of directly before him; thus each half of the 
twin frustule occupies a position at right angles to what the 
parent frustule did, and which the perfect separated one 
ought to do. Finally, the two portions of the double frus- 
tule separate from each other in front like the two valves of 
a mussel-shell ; the amount of separation depending on the 
strength of the remains of the siliceous band that connects 
them, and causing the general outline to vary extremely. 
In characterising or figuring the forms of this genus, it 1s 
therefore necessary, for the sake of comparison, that each be 
viewed under precisely the same circumstances ; moreover, so 
many changes take place whilst the process of self-division 
goes on, that no descriptions or figures are of much use in 
the identification of permanent forms or species, unless when 
taken from the simple but perfect frustule before self-divi- 
sion commences, or from its valves. 

Although the structure of the genus adopted by Kutzing 
and Smith be not what I conceive the correct one, no practical 
inconvenience arises, as their specific characters have been 
selected from the same parts on which they must otherwise have 
relied. It is, however, somewhat different with that given by 
the late Dr. Gregory in his paper in vol. xxi of the “Trans. of the 
Royal Soe. of Edinb.’ p. 510; but here I experience consider- 
able difficulty from his having introduced into his descriptions 
several terms, neither employed by any other writer, nor ex- 
plained by himself, the meaning of which the reader is left 
to discover. From a careful comparison of the figures, I 
presume that by “ventral margin” he intends sometimes 
both the anterior and posterior margin of the folded valve, 
and sometimes the irregular margin of a portion of the still 
adhering connecting membrane; by “ dorsal margin,” the 
outline of the frustule; and by “inner curve line,” the 
median line of the valve ; most of which vary in appearance 
according to the position presented to the eye by the frustule 
during self-division. There are other terms, however, about 
which I am more doubtful; as “inner margin,” “outer 
margin,” and inner or outer “‘ compartments of the valves ;” 
although it is probable that all, im some way, refer to the 
connecting zone. Dr. Gregory’s theory is, that “ what is 


206 WALKER-ARNOTT, ON ARACHNOIDISCUS, ETC. 


usually called the entire frustule” consists of “two frustules 
in the act of self-division,” and consequently of four valves, 
and it results from this that what is commonly called a 
single frustule is composed of two new valves, forming or 
formed, in addition to the two primary ones ; in short, that 
the small portion seen in front alone belongs to the original 
frustule. If we now take what is usually called a double 
frustule (as in Smith’s fig. 28 d), which by Dr. Gregory’s 
theory must consist of four frustules or eight valves, three- 
fourths of the whole must be either in the transition state, or 
represent six valves, each identical with the two original ones, 
but in a different position. As I cannot suppose that Dr. 
Gregory intended to take distinctive marks from the connect- 
ing zone in its variable state, or from more valves than one, 
or from their accidental relative position, it appears to me 
that his hypothesis, if correct, would much increase the 
difficulty of finding constant characters, and cause the rejec- 
tion of several on which he depends, as well as the annihila- 
tion of many of his new forms. 

I may here mention that A. marina of Smith, alluded to 
by Dr. Gregory under his No. 76, is precisely what Dr. 
Gregory calls 4. Proteus. Smith’s figure (‘ Ann. of Nat. Hist.’ 
for 1857, vol. xix, tab. i, f. 2) is far from good, and represents 
the double frustule towards the close of the self-dividing 
process. Some years ago Smith gave it the MS. provisional 
name of A. Scotica, from its having been first detected on 
the west coast of Scotland by Mr. Hennedy of Glasgow ; he 
omitted it in the second volume of his ‘ Synopsis,’ being not 
quite satisfied with its claims to be specifically distinguished 
from A. affinis ; but these doubts were removed by afterwards 
finding it in the summer of 1856 near Havre and Biarritz, on 
the French coast, and thus having an opportunity of study- 
ing it in the living state, and drawing up a specific character. 


207 


On some Britisu FresH-waTter ALG. 
By Freperick Currey, Hsq., M.A., F.R.S. 


Tue observations to which this paper relates were made in 
the year 1856, and have since been laid by under a doubt 
as to their being of sufficient importance to be made public ; 
but some recent observations inGermany have induced me to 
think that they may not be without value, especially if they 
should have the effect of directing the attention of some of 
the numerous microscopists of the present day to the abund- 
ance of material for interesting and important microscopical 
inquiries afforded by the fresh-water Alge. 

The first matter to which I wish to direct attention is a pecu- 
har condition of fructification of the common Draparnaldia 
glomerata. When this plant is taken from the water, it pre- 
sents, as 1s well known, a shiny gelatinous mass of a uniform 
yellowish green colour, and without the aid of the microscope it 
is impossible to trace its structure. In the month of April, 
1856, I found, in a pool of water in a gravel-pit in Cobham Park, 
a quantity of Draparnaldia glomerata, in which the jelly 
was traversed by multitudes of dark-coloured feathery-look- 
ing lines, clearly visible to the naked eye, and upon examin- 
ing it with the microscope, it appeared that almost all the 
side shoots of- the Alga had become transformed into rows of 
globular brown cells, arranged in a moniliform manner. 
These cells were, in most instances, in close contact with 
one another, but here and there single cells were to be seen, 
which, although isolated, clearly belonged to the same con- 
geries. It was obvious that these brown cells had been 
originally formed in the interior of the joints of the side 
shoots of the Alga, and were, at the time of the observation, 
gradually becoming free by the dissolution of the walls of 
the parent cells, the debris of which helped to form the ge- 
latinous medium in which they were immersed. Fig. 1 
represents the general appearance of a portion of the plant 
under a power of 200 diameters. It will be seen that at one 
point, at the extremity of one of the shoots, the formation 
of the brown cells is not complete, the three terminal cells, 
retaining still their primary oblong form and their original 
pale green colour. I am not aware that this state of fructi- 
fication in Draparnaldia has ever been described. The or- 
dinary mode of reproduction of this Alga is by zoospores, 
which are emitted from the cells of the ramuli, and which 
are of a sub-globose or elliptical shape, and furnished with 


208 CURREY, ON FRESH-WATER ALGA. 


four cilia. I find in the ‘ Regensburg Flora’ for 1855, a de- 
scription of the fruit of a Draparnaldia, published in Ra- 
benhorst’s collection, which is probably of the same nature 
as that which I have described above; the notice in the 
‘Flora’ is very short, and speaks of the specimen as being a 
curiosity on account of its fruit. 

There can, I think, be little doubt that these brown globu- 
lar cells are of a nature similar to that of the orange-coloured 
cells of Volvox, and the red cells of Bulbochete, Chlamydo- 
coccus, and other Algz; that is, that they are the resting 
cells, or, as they are sometimes called, winter spores, capable, 
as all such spores are, of undergoing desiccation for a 
lengthened period, and reviving again when circumstances 
become favorable to their development. 

I kept the bottle containing the Draparnaldia byme for some 
weeks, at the end of which time most of the brown cells had 
disappeared, and the water contained a mass of green Alge, 
which, at first sight, might have been supposed to belong to 
the genus Gleocapsa, but which appeared to me to have 
originated from the division of the contents, and from the 
softening and consequent enlargement of the outer mem- 
brane of the brown cells of the Draparnaldia. 

If these Gleocapse originated in the manner I suppose, 
the contents of the brown cells must have changed their 
colour during the process, but this, as is well known, is by 
no means an uncommon occurrence in the fresh-water Alge, 
when entering upon a new phase of vegetation. Not having 
had leisure at the time to follow out the process from day to 
day, I cannot state positively that the Gleocapsa-like Algze 
originated in the manner above mentioned, but it can hardly 
be doubted that such was the case, and the point is one which 
may afford matter for interesting mvestigation to any micro- 
scopist who may happen to meet with the Draparnaldia in the 
state of what may be called its winter fructification. 

The Gleocapsz, if I may so call them, which resulted from 
the division of the contents of these resting cells of Drapar- 
naldia, consisted each of a gelatinous envelope enclosing a 
number of small motionless green cells, or gonidia. In 
the oospores, or spores formed after copulation, of Spirogyra, 
I have seen the cell-contents divide into a number of 
round motionless cells, guite devoid of colour, and I have seen 
a similar process in one of the large orange-coloured spores of 
the so-called Volvoxw aureus, which is only the resting form 
of Volvox globator, where the contents divided into five 
globular colourless cells, which floated in a mass of reddish 
plasma, being apparently the remains of so much of the original 


CURREY, ON FRESH-WATER ALG. 209 


contents of the cell as had not been absorbed in the forma- 
tion of the secondary cells. 

There is, however, another mode of self-division where the 
spore, or resting cell, divides first into two and then into four 
segments, each segment being the counterpart of the original, 
which thus produces a new generation of resting cells. This 
latter mode of division has been supposed to take place 
in the red resting cells of Chlamydococcus; but it has 
been recently stated by Professors Cohn and Wichura that 
this case requires further proof. I am enabled to furnish 
some evidence on the point, for I have distinctly observed 
the process of self-division in some red resting-cells, which 
were probably those of Chlamydococcus. I say prodably, 
because the red resting-cells of Chlamydococcus are quite un- 
distinguishable from those of another of the Volvocinez, viz., 
Stephanosphera pluvialis, so that without following out the 
development it is impossible to predicate whether such red 
cells belong to the one or the otlier. 

Pl. IX, fig. 2 shows an instance in which one of these cells 
has become divided into two parts; and Fig. 3, an instance in 
which the self-division has gone further, andthe original cell 
has become separated into four secondary cells, each precisely 
similar to the primary one. 

In a recent paper by Cohn and Wichura, published in the 
Transactions of the Bonn Academy, and an abstract of which 
appeared in the last number of this Journal, a question of 
some physiological interest has been raised with regard to 
the nature of these red resting cells. They observed that 
these cells in Slephanosphera pluvialis, which are at first of 
‘a green colour, and furnished with cilia, increase in growth 
after the green colour and the cilia have disappeared, #. e., 
after they have assumed a state of rest, a fact which they 
consider to militate against their character as spores. 

“We have seen,” they say, “ that these resting cells, after 
they have been formed by the metamorphosis of a motile 
primordial cell, increase in growth considerably ; that they 
go through a further vegetative development, and have, 
therefore, not reached the termination of their vital process.” 
And they then add: “It is contrary to the idea of a spore, 
that it should continue to grow after having assumed the 
character of a resting cell, and the fact has never yet been 
observed in any single case.” It would seem that these re- 
marks are intended to be limited to the Alge; but it is 
worthy of observation, that the spores of the ascigerous Fungi 
frequently increase in growth, after escaping from the asci, 
and if this circumstance is not to be looked upon as affect- 

VOL. VI. R 


210 CURREY, ON FRESH-WATER ALGAE. 


ing their character as spores, it 1s difficult to see why a dif- 
ferent rule should be applied to the Alge. 

Cohn and Wichura moreover consider that the increase 
by self-division is irreconcileable with the idea of a spore. 
In speaking of the red cells of Chlamydococcus pluvialis 
they express a doubt whether, in those cells, imcrease by 
self-division takes place, but assert, that if such should prove 
to be the case, it would be conclusive against their being 
spores, considering self-division (if I understand them right) 
to be a process of vegetative development distinct from 
germination. ‘These observations are worthy of the careful 
attention of microscopists, and without venturing an opinion 
as to their correctness, I would only remark, that if the rest- 
ing cells of Chlamydococcus and Stephanosphera are not 
to be considered spores, that character must also be denied 
to the resting cells of idogonium, Bulbocheete, Draparnaldia, 
Spheroplea, and Volvox, if, as is more than probable, there 
should be detected in these latter cells,—1st, an increase in 
growth, after becoming quiescent, or, 2dly, increase by self- 
division. 

2. I now proceed to notice some minute parasitic organisms, 
which will be best dealt with by simply describing them, 
inasmuch as it is impossible, with any certainty at least, to 
assign them a definite place amongst the fresh-water Algze. 
Their form is that of small globular vesicles, furnished with 
a stalk, the length of which is sometimes about equal to the 
diameter of the vesicle, sometimes considerably greater. I 
have observed them growing upon zoospores, and also upon 
the large oval resting spores of a species of Spirogyra. The 
zoospores were of a bright green colour, and of rather a small 
size, as will be seen by refering to fig. 4, which represents one of 
them magnified 220 diameters, and withthe parasites attached. 
The latter are quite colourless, and the globular head ex- 
hibits a well-defined nucleus. The zoospores upon which they 
grew were in the most active motion, revolving first in one 
direction and then in another, looking and as if they were 
attempting, by the rapid changes of their movements, to 
shake off and rid themselves of the incubus of the parasites. 
Not having seen the zoospores in their parent cell, I am 
quite unable to say from what plant they were produced. 
The number of the parasites on the zoospores was variable, 
not, I think, exceeding five or six on any one zoospore ; but, in 
the case of the Spirogyra (fig. 5), they grew so thickly as 
almost to conceal the spore, the individuals being precisely 
similar in form and appearance to those on the zoospore. 
Should these bodies come under the notice of any of the 


CURREY, ON FRESH=-WATER ALG. 211 


readers of this Journal, I would venture to express a hope 
that they may be carefully watched. It is not, I think, im- 
probable that they may prove to be undeveloped forms 
either of some species of Chytridium or Rhizidium, or of the 
genus Pythium; but without following out their develop- 
ment, this point cannot be decided. The only plant I know 
which at all resembles them is Chytr idium apiculatum 
described in Dr. Braun’s monograph of the genus Chytridium, 
and figured by him in Pl. V , fig. 10, of that monograph ; but 
it will be seen, by comparing his ‘ficures with fig. 4, above 
referred to, that there is a marked diffe erence In fori between 
his species and the present organisms. 

Pythium is a genus separated from Achlya and Saproleg- 
nia, by Dr. Pr inesheim, in his paper on the Saprolegniez, 
in the last part of the ‘ Jahrbiicher ftir wissenschaftliche 
Botanik.’ The distinctive features of the genus are—l1st; 
that the contents of the sporangium are ejected before the 
formation of the zoospores, and out of the mass thus ejected, 
but which adheres to the sporangium, the zoospores are 
subsequently developed; 2dly, that the oogonia, or spore 
cases, produce only one resting spore, instead of several, as is 
the case in Saprolegnia and Achlya. 

I have stated that the parasitic Alge just described weré 
attached to a species of Spirogyra, and I may mention (as it 
has not been often seen), that several of the resting spores 
of the Spirogyra, to which the parasites were not attached, 
commenced germination during my observations. The ger- 
mination of these spores is a matter of some interest. It 
was first mentioned by Vaucher fifty years ago; afterwards 
Dr. Hassall, in his ‘ British Fresh-water Algze,’ considered 
Vaucher to have been altogether mistaken; but some years 
later the germination was again noticed by Dr. Pringsheim 
and by the late Professor Smith, and the correctness of 
Vaucher’s observations placed beyond doubt. In figs. 6; 7, 8; 
and 9, Pl. IX, [have drawn some of these germinating spores. 
At the period of germination they consist of three membranes, 
the imner one enclosing the cell contents, which become 
green just before the germ breaks forth. In fig. 7; the outer 
membrane, which is seen loosely attached, was colourless ; 
the second membrane, which (see figs. 7 and 8), has opened; 
to give exit to the germ, was at this period of a pale brown 
colour, and transparent. In fig. 8 the young germ has be- 
come three- celled, and there is a slight tendency in the 
endochrome to assume a spiral form, and the remnant of the 
spore is still attached. In fig. 9 the germ has become free, 
and the endochrome more visibly spiral. 


212 CURREY, ON FRESH-WATER ALGH. 


3. The next plant which I have to mention, is one which 
has not hitherto been observed in this country.* I have only 
found a single specimen, and that in a young state, but 
there is no difficulty in identifying it with the species de- 
scribed by Dr. Braun, in his ‘ Algz unicellulares,’ under the 
name of Sciadium arbuscula. 'This Sciadium arbuscula is an 
Alga of very singular growth. It consists, in its first stage, 
of an erect cylindrical elongated cell, furnished with a very 
short narrow stem at the base. ‘The endochrome of this cell 
breaks up into separate portions and forms, from five to ten, 
usually eight, gonidia, arranged at first in a single row. 
Afterwards the apex of the cell opens by a circumscissile fissure, 
and the gonidia protrude through the orifice and form an umbel 
of cells. The cells forming this umbel grow into elongated 
cylindrical cells, precisely similar to the parent-cell. Their 
stems are united into a fascicle just mside the mouth of the 
tube of the mother-cell, but are not long visible, owing to a 
dark-coloured secretion, which forms round the bases of the 
cells at an early period of their growth and completely ob- 
scures the stems. The branches of the primary umbel pro- 
duce gonidia, which go through the same process, and thus 
secondary umbels are formed, from which, in process of 
time, tertiary umbels are produced. ‘The gonidia which are 
formed in the branches of the tertiary umbels, instead of 
remaining united at the apices of the branches, escape from 
their mother-cells, but it is not certain whether they emerge 
in the form of zoospores, or as motionless cells. Dr. Braun 
has not observed their actual escape, but has seen zoospores 
agreeing in size and form with the gonidia of Sciadium 
moving about, amongst the specimens of that plant, and 
which, in his opinion, had their origin im the cylindrical 
cells. 

Fig. 10 represents the British specimen which occurred in 
a pool on Paul’s Cray Common, in Kent, in the spring of 
1856. The cylindrical cell was colourless for the greater 
part of its length, but the tip was almost black, having, how- 
ever, a reddish tinge, the colour being so dark as quite to 
obscure the stems of the transparent green gonidia, which 
protruded, eight in number, from the apex of the mother- 
cell. I did not see the short filiform stem noticed by Dr. 
Braun ;+ but, on referring to his figures, it will be seen that 


* I have this spring observed two more specimens in water from the 


same locality, both in the same stage of growth as the one described in the 
text. 


t This stem was plainly visible in the specimens which occurred this year. 


CURRKEY, ON FRESH-WATER ALG. 213 


this stem is very short, in comparison with the length of the 
cell which it supports, and might easily be concealed by the 
body to which the Sciadium was attached. Sciadium arbuscula 
forms an interesting addition to our British fresh-water Algee. 

4. Pandorina Morum, Ehr.—-This plant was described, with 
some other Confervoid Alge, by Mr. Henfrey, in the fourth 
volume of the ‘Transactions of the Microscopical Society.’ 
It had been previously seen by Mr. Shadbolt, and probably by 
many other observers; but, notwithstanding Mr. Shadbolt’s 
remarks in his presidential address for 1856, it is clear that 
Mr. Henfrey was right in describing it as new to England, 
the test of novelty being, not whether it had been previously 
seen, but whether it had been published as a British Alga. 
In speaking of the reproduction of Pandorina, Mr. Henfrey 
mentions two processes—1, the conversion of each gonidium 
into a new frond within the parent mass; and 2,.the conver- 
sion of the gonidia into encysted resting spores, which are 
set free, and subsequently germinate to produce new fronds. 
Upon this I may remark, that the process of becoming 
encysted does not invariably take place within the parent 
frond, for I have seen the gonidia of Pandorma escape from 
the parent frond in the form of membraneless active zoo- 
spores ; and although I was not fortunate enough to trace the 
subsequent fate of these zoospores, the probability is that, like 
those of Chlamydococcus and Gonium, they would become 
encysted at a subsequent period, as without undergoing this 
process it is difficult to see how they could produce new 
fronds. This mode of escape of the zoospores seems to throw 
some doubt upon the suggestion of Mr. Henfrey, with re- 
gard to the nature of the frond of Pandorina, which he con- 
siders to be solid, inasmuch as it does not give way or be- 
come indented by pressure, as is the case with the hollow 
frond of Volvox. If, however, the frond were sold, the 
zoospores could not well escape except by its gradual dis- 
solution, but, in the instance I have mentioned the escape 
certainly took place by a rupture (as may often be seen 
with Volvox), and not by a gradual process of dissolu- 
tion. In a paper on some Volvocinee, by Dr. Fresenius, in 
the second volume of the Transactions of the Senckenberg 
Natural History Society, he speaks of the easy escape of 
the cells of Goniwm pectorale, as bemg evidence against 
the existence in that Alga of any firm covering, and he 
draws a distinction in this respect between Gonium and 
Pandorima. My observation, however, leads me to think 
that Pandorina, as far as relates to its coat, does not sub- 
stantially differ from Volvox and Gonium. Besides the na- 


214 CURREY, ON FRESH-WATER ALG. 


ture of its coat, there are some other points of structure in 
Pandorina requiring further examination and elucidation. 
Ehrenberg stated that the gonidia of Pandorina have one 
cilium, and no eye-spot, a view adopted by Fresenius, in the 
paper I have alluded to. Focke and Dr. Braun considered 
Ehrenberg’s observations inaccurate, and Mr. Henfrey agrees 
with them. As far as my observations go, I should say that 
the gonidia have usually two cilia, but that they frequently 
have no eye-spot. Mr. Henfrey has never been able to observe 
a pulsating vacuole, nor was any such vacuole visible in my 
specimens. Dr. Fresenius, on the other hand, has observed 
one, sometimes two, such vacuoles; and he remarks, that 
cilia and red spots are subject to considerable variation, and 
suggests that Stephanosphera and Volvox are probably the 
only distinct forms to be met with in the Volvocinee. I 
should protest against including Goniwm pectorale in the 
same genus as Stephanosphera; but, with this exception, 
Dr. Fresenius’s suggestion is probably correct. If, however, 
Stephanosphera and Pandorina are only forms of the same 
plant, the generic name ‘ Stephanosphera’. must give place to 
‘Pandorina,’ the latter bemg of much earlier date. 

A reference to Mr. Henfrey’s figures will show how much 
variety exists in different specimens of Pandorina. In figs. 
11—17 I have drawn several forms, all probably referable 
to Pandorina, which came under my own observation. Fig. 
12 is a large globe, filled with encysted berry-like masses, 
the membrane standing out a considerable distance from the 
gonidia. ‘This form was not in motion, although the cilia of 
the internal fronds (some of which are, from the size of the 
object, out of focus) were most clearly perceptible. Fig. 16 
shows a similar but much smaller frond, in which the cilia 
were not visible. Fig. 15, a frond in which only one ailium 
was apparent, but I cannot state positively that two did not 
exist. 

5. Monostroma roseum, n. sp.—This Alga, a species not 
hitherto described, seems to unite the characters of a Mono- 
stroma and a Palmella. It is to be found, usually in some 
quantity, in a stagnant pool at the conduit-head in the fields 
between Eltham, in Kent, and Halfway Street, and I have 
met with isolated specimens in two other pools near Shooter’s 
Hill. All three of these pools are lined at the bottom with 
particularly fetid black mud, but the water itself is clear. 
The fronds are of a bright pink, or sometimes lilac colour, 
and consist in their early stage of a hollow globular mem- 
brane, formed of closely approximated cells. Figs. 18 and 
19 represent two young fronds magnified fifty diameters ; 


CURREY, ON FRESH-WATER ALG. 215 


of which fig. 19, by the rupture at the apex, clearly shows 
that the interior is hollow and not solid. A power of fifty 
diameters is quite insufficient to show the constituent cells, but 
their nature is clearly seen in fig. 22, which shows a portion of 
a more advanced frond magnified nearly 700 diameters. It is 
but rarely that specimens such as those in figs. 18 and 19 
are obtainable. The membrane, instead of remaining of a 
globular shape, very soon becomes bent and crumpled into a 
variety of forms, as shown in figs. 20 and 21. The fronds 
are very delicate, and are apt to be put out of shape even 
by the pressure of the thin glass cover, and it is advisable, 
therefore, to examine them in a thin cell, or at all events to 
prevent the direct pressure of the glass cover upon them. 
In process of time the fronds lose altogether their mem- 
branous nature, and when full grown they consist of a gelatin- 
ous mass, with multitudes of small cells imbeddedin it. By 
bringing the margin of a frond into focus, it is seen that the 
gelatinous mass extends considerably beyond the outermost 
cells, and a very slight pressure disperses the jelly and sets 
free the minute imbedded cells. The full-grown fronds are 
usually of irregular shape, but with a length or diameter 
sometimes as great as one fifteenth of an inch or even more. 

It will be seen, therefore, that the Alga just described 
might, at one period, be classed with Monostroma, at a 
later with Palmella. The gelatinous mass doubtless arises 
from the partial dissolution, as well of the walls of the pri- 
mary cells constituting the original membranous fronds, as 
of the walls of the cells produced by the self-division of such 
primary cells. 

6. Clathrocystis @ruginosa, Henfrey.—In figs. 23 and 
24 I have drawn an Alga, which seems to be identical with 
Mr. Henfrey’s Clathrocystis eruginosa, figured im ‘ Trans. 
Mier. Soc.,’ vol. iv, figs. 28—36. It differs somewhat in the 
much greater number of reticulations. In this case, as in 
that of Monostroma roseum, there seems to be a transition 
from hollowness to solidity. In fig. 23 the frond has a re- 
ticulated structure, and having been split open by a clean 
fissure, has the appearance of being hollow in the interior. In 
fig. 24, on the other hand, the green cells seem to be im- 
bedded in solid, soft, and colourless gelatinous matter. Fig. 
25 shows a mass of the component green cells; and fig. 26, 
some of the same cells detached. They vary much in size ; 
the secondary cells in the interior of the larger ones being 
similar to the smaller free cells. ‘The mass of cells was much 
grown over with small colourless Spirilla, as shown in fig. 25; 
this was the case in very many, if not most, of the fronds. 


216 CURREY, ON FRESH-WATER ALG#. 


Nostoc minimum (? n. sp.) —Frond ellipsoidal, very minute, 
about1-120th inch, cells of the filaments somewhat square, but 
constricted in the middle on two sides, giving the filaments 
a crenate outline; vesicular cells globular and colourless. Had. 
In a pool (which dries up in hot weather) on Paul’s Cray 
Common, Kent, June, 1856. 

Fig. 27 represents this species, which, as far as I know, is 
undescribed. I have named it for convenience of reference, 
although new species of Nostoc should be admitted with 
caution, the genus even being of doubtful validity.* 

In conclusion, I have only to notice shortly the plants 
drawn in figs. 28 and 29. Fig. 28 I take to be a state of 
Chlamydococcus. The outer membrane was colourless, and 
the two internal globular cells of a clear bright ruby crimson. 
The pecularity of the plant consisted in the fact of the 
cell being filled with mimute staff-like subcylindrical bodies 
in active motion, precisely similar to the Spermatozoa of 
Vaucheria.t I watched these bodies at intervals for about 
twenty-four hours, and the motion was incessant. At the 
end of that time the cell slipped amongst some other Algze 
on the same side and was lost. Whether these little active 
organisms were really Spermatozoa, or whether they belonged 
to the mysterious bodies which, in some way or another, are 
supposed to find their way from without into the cells of 
Algz, it is impossible to say. 

The other figure (fig. 29) represents, no doubt, the 
final stage of some Volvocine$ in which the gonidia have 
become encysted. 

I notice it because the encysted cells were of a pale yellowish- 
brown colour, and covered with minute pits or depressions, 
and were altogether different from those of any other Alga 
with which I am acquainted. In Pandorina and Stephano- 
spheera, the resting spores are red, in Volvox bright orange, 
and in neither case are there any such markings as those in 
the membranes of the cells shown in fig. 29. 


* See Bayrhoffer, Entwickelung, &c.; von Thrombium Nostoe, Bo- 
tanische Zeitung, 1857, p. 137; and Itzigsohn, ‘ Phykologische Studien,’ 
Nova Acta, vol. xxiv, pp. 1839—156. 

+ See ‘ Micros. Journ.,’ Vol. 1V, Pl. III. 

t As to these bodies, see ‘ Bot. Ziet.,’ 1857, No. 14, and Pringsheim’s 
‘ Jahrbiicher,’ Part i, p. 371. 

§ I have coined this substantive to avoid the periphrasis of “one of the 
Volvocinex,” or “a Volvocineous Alga.” 


BLACKHEATH Park, 8.E., 
June 1, 1858. 


217 


On the Srructure of the Retina. By Tuomas NunnzE ey, 
F.R.C.S.E., Lecturer on Surgery in Leeds School of 
Medicine, Surgeon to the Leeds General Eye and Har 
Infirmary, &e. 


Tue retina is the sentient part of the eye, for which all 
the other textures are formed, and to which they may be said 
to be subservient. It is coextensive with the choroid proper ; 
it covers the whole of the convex portion of the vitreous 
humour, and is covered by the choroid. It terminates in a 
serrated line, ora serrata, which is readily seen with an inch 
lens, just where the ciliary processes are continuous with the 
choroid. There is, according to some anatomists, a circular 
blood-vessel running near to this edge, if so, it is probably 
a vein, but it rather appears as a series of capillary loops of 
the central artery. Some of the older anatomists and opti- 
cians described the retina as being continuous over the 
anterior surface of the crystalline lens, an opinion which has 
been adopted to a great extent by Arnold, who describes and 
figures the retina as being continuous with the ciliary body 
and processes to the edge of the lens,*—wpars ciliaris retine 
and processus ciliaris retine. This, however, is, without 
doubt, an error ; though the retina does not terminate wholly 
and absolutely at the ora serrata, as is commonly described. 
The nervous structure here ends, but there is, contimuous 
with the suspensory ligament of the lens, a cellular layer, as 
far as the edge of the lens: this is best seen after the eye 
has been kept for some time in spirit or Goadby’s solution, 
by which the layer is rendered opaque and white. Its con- 
tinuity with the retina may then be readily traced, and, 
indeed, in some eyes it looks so hke a continuation of the 
whole retina as to render the microscope essential to prove 
that the nerve-structure is not so prolonged.t The retina 
has, until very recently, been described as the terminal ex- 
pansion of the fibres of the optic nerve into a membrane. 
It is, however, much more than this; it is one of the 
most complex, perhaps the most complex, structure to be 


* ¢ Tcones organ. sen.,’ tab. 3, fig. 2. 

{ In one instance of an alligator, I find a memorandum I made at the 
time of the dissection, to the effect that the retina was traceable to the 
edge of the lens; but as this was made before I was so well acquainted 
with the different structures in the retina, and the eye was not very fresh, 
I should not rely upon this apparent exception, but look carefully at these 
parts when opportunity again offers a similar creature. 


218 NUNNELEY, ON THE RETINA. 


found in the body, and instead of being thought of as simply 
a terminal nervous expansion, it should be regarded as in 
itself a nervous centre; having the fibres of the nerve ex- 
panded it is true in it, and by “which it is connected with the 
brain, but possessed itself of structures and properties 
peculiar to it, and altogether different from those of the 
optic fibres, which are expanded in and make part of it. 
These fibres are for the purpose of conveying to the sensorium 
the impressions excited in the retina, but are not for receiving 
the impression, while the other complex structures of the 
retina receive and appreciate the impressions of external 
objects. 

The inner surface of the retina is not merely superimposed 
upon the vitreous body, but is organically connected with it, 
by a series of clear, perfectly transparent cells ; while the 
outer surface is most intimately united with the cells forming 
the mner layer of the choroid. It is an extremely delicate, 
thin structure, thickest at its junction with the optic nerve, 
and gradually becomes thinner as it reaches the ora serrata, 
where it is not more than a quarter the thickness it possesses 
at the back part of the eye.* 

In the living condition the retina is as nearly transparent 
as possible, and of a slight pmk tinge, but in a very short 
time after death it becomes translucent, then opaque: by 
immersion in water it very soon becomes so; and by spinit, 
heat, and all chemicals which coagulate albumen, it 1s Im- 
mediately rendered quite opaque and white. In the fresh 
eye it is perfectly smooth, but, in consequence of evaporation 
from the eye, it is at the period when human eyes are com- 
monly dissected found in irregular folds. |The pink tinge of 
the fresh retina is due to the blood which it contains. It is 
a very vascular structure, deriving its supply of blood from 
the central artery of the retina, and, not improbably, some 
of its nutriment, though no vessels, from the choroid coat. 

So numerous and complex, so minute and fragile, so 
transparent and changeable, so intimately connected and 
mingled together, so quickly altering after death, and yet, 
at least in man, so difficult to obtain immediately after death, 
so instantly and most importantly altering on the addition 
of almost every agent that may be employed i in assisting Mm 
the examination of other tissues, that it is no wonder almost 
every description of these structures is different from others ; 


* Kolliker says, ‘“ Its thickness is at first 0°1 of a line, but as it extends 
acai it soon diminishes to 0:06 of a line, until ultimately close to the 
anterior border of the retina it is not. more than 0:04 of a line in thick- 
ness.” (‘ KOlliker’s Human Histology,’ by Busk and Huxley, vol. ii, p. 369.) 


NUNNELEY, ON THE RETINA. 219 


and that one microscopist should find appearances which 
others have not. Hence, notwithstanding the careful labours 
of many of the most eminent anatomists and observers, it is 
very doubtful if we are yet in possession of the real living 
structure of all the parts in this wonderful tissue. Certain 
I am that many statements are incorrect, that post-mortem 
changes have been confounded with normal living forms, 
and alterations effected by reagents have been described as 
natural conditions. Thus, while it is easy to say that some 
of the descriptions are certainly not correct, it is by no 
means so easy to feel certain that one’s own observations, 
however carefully and repeatedly made, are not also open to 
error. While, therefore, I have taken all the care I can, and 
spent much time upon the investigation, I would wish to be 
understood where differmg from other anatomists in the 
description of these parts, as doing so with the greatest 
deference, and with the full recognition of the weight 
attached to their skill and experience in the use of the 
microscope, and as only stating that which I believe to be 
the forms during life of these minute structures, and not as 
asserting dogmatically what is incapable of dispute.* 

The retina consists of several layers superimposed upon 
each other ; commencing externally, these are— 


* | believe the only way to examine the retina unchanged is to do so 
immediately after death, and without the addition of axy substance whatever. 
So rapidly do the rods undergo change, that in a few hours they are com- 
pletely altered; and not unfrequently even when taken from the living eye, 
they are seen to alter while under examination. IL know of no fluid which 
does not more or less change them. Even chromic acid, which Kolliker so 
extols, is not without greatly modifying influence upon the true retinal 
elements; and water émmcediately materially alters, and soon quite destroys 
the rods, and alters the granules and bulbs. It is extremely difficult pur- 
posely to make a section sufficiently thin in the fresh retina to examine it 
im profile; and, if expanded and dried, it requires maceration to render it 
fit for examination, by which the structures swell and alter irregularly, 
whatever fluid be used, so that the natural forms are not obtained; but 
these examinations are important as helping the inquiry, and by employing 
different fluids the one error may to some extent correct the other. The 
fluid which I have found to preserve the retina in the most natural condition 
for the longest time, is Goadby’s solution, No. 1, diluted by one half. My 
experience Of chromic acid is much less favorable than | had been led to 
expect by the statement of Kolliker and others. It is true it renders the 
cerebral elements of the retina, the nerve-fibres, the nucleated cells, and the 
granules or granular cells, more distinct; but its action upon the rods and 
conoidal bodies is very considerable—if strong, there is one confused fibrous 
mass, coloured yellow by the acid; if much diluted, the rods break up into 
dises and granwes, and the cones soon swell and disintegrate as with water. 
I doubt if its action be greatly superior to that of diluted acetic acid, which 
has the advantage of being colourless. 


\D 
we 
= 


NUNNELEY, ON THE RETINA. 


1. The columnar or bacillar layer, rods, Jacob’s mem- 
brane. 

2. Bulbous or conoidal bodies. 

3. Granular layers. 

4, Nucleated vesicular layer. 

5. Vascular layer. 

6. Fibrous layer. 

7. Hyaloidal cellular layer. 


1. The outermost layer of the retina is really a wonderous 
structure. It is quite peculiar to the retina, but is found 
in all animals where there is a retina, even in the eye-dot of - 
the “blind mole.” It consists of mimute cylindrical bodies as 
innumerable as the sand upon the seashore. ‘They are Rops 
or COLUMNS, arranged side by side, and stand perpendicularly 
to the centre of the eye; the outer ends are in close con- 
nexion with the choroid coat, the inner ends rest among the 
granules which form the third layer; they consequently 
stand at right angles to the fibrous expansion of the optic 
nerve. They may be traced uninterruptedly from the expan- 
sion of the optic nerve to the ora serrata; they are consider- 
ably the longest at the former situation, and appear gradually 
to decrease in length towards the fore part of the retina. 
They are so closely arranged as to constitute a complete coat. 
In man, mammalia generally, reptiles (except the chelonian,) 
and fish, they appear to be perfect cylinders, with clear, dis- 
tinct, straight, transverse ends. In chelonians and birds, 
there are a few cylindrical, but they are for the most part 
bulbous or conoidal; the larger end bemg outmost. They 
have been sometimes described as six-sided prisms; un- 
doubtedly not unfrequently they appear hexagonal—this, 
however, merely arises from their being compressed against 
each other, where not so they are perfectly round. In the 
frog and the toad by far the greater number are perfect 
cylinders, but I have seen some few amongst the mass with 
one end broader than the other. They are solid, perfectly 
transparent, highly refractive rods, quite straight in_ the 
living eye, but they very soon become variably distorted, as 
bent at right angles, particularly towards one extremity, the 
outer, or curled up at one end, like the hook of a walking- 
stick, as represented as the normal condition by Hassall ; 
but of which not a trace is to be found in the eye of an 
animal just killed. They then curl up into oval or circular 
rings, so as to look very much like cells, and may easily be 
mistaken for blood-cells; occasionally they split longitudi- 
nally, but far more commonly they become marked by 


NUNNELEY, ON THE RETINA. 221 


transverse striz and look like connected discs, then granular, 
and ultimately break up into transparent granules, and alto- 
gether disappear, so that in six, twelve, or twenty-four hours 
after death, hardly a straight, clear cylindrical rod is to be 
seen, and frequently in forty-eight hours or less not a trace 
of them is left. 

They are very flexible, and may be seen to bend on en- 
countering any obstacle—as when detached from each other 
they float about—and immediately this is passed, to again 
become straight ; but I do not think they are elastic, that is, 
compressible. They are at the same time, very brittle, and 
most easily break. They appear neither to attract nor repel 
each other, but when brought imto contact they often adhere 
by the parts which actually touch, so that if they happen to 
come end to end, two may easily be mistaken for a single long 
rod. They are largest in reptiles generally, and of these 
in the frog; next in fish, and smallest in man and mamma- 
lia. Though their size varies in different creatures, it bears 
very little proportion to the size of the animal or of the eye- 
ball. Thus the rods of the frog, toad, and water-newt are 
as large or larger than those of the alligator; of the sparrow 
and canary bird as those of the fowl or turkey; of the 
duck as those of the swan; of the carp, trout, eel, and 
herring as those of the halibut, salmon, haddock, and cod. 
Those of the rat, mouse, and mole are nearly as large as 
those of the sheep, ox, and horse; of the monkey as those 
of man; indeed those of man, if anything, are smaller, 
and, I think, more numerous than in almost any other 
creature. 

I have stated that I believe these in the living eye to be 
straight cylinders, but this is not the usual description. 
Hassall has described and figured them as curled into a 
knob at the outer extremity. This is a very common ap- 
pearance when the eye has not been examined until the 
animal has been dead a short time, but certainly does not 
exist in the living eye; and may often enough be seen to 
form while the examination is going on; especially on the 
addition of dilute spirit, or after the unopened eye has been 
immersed in it for a short time. On the other hand, Han- 
nover, in his beautiful plates (‘ Recherches microscopiques sur 
le Systeme nerveux’) has described and figured all the rods 
as terminating outwardly in a conical extremity; this being 
in some animals prolonged into a long delicate filament, 
which is, he says, received into a minute sheath formed in 
the choroid coat, whereby the two tissues are organically 
connected together. In this he is followed to some extent 
by Mr. Bowman. 


222 NUNNELEY, ON THE RETINA, 


For this cone at the outer extremity of the rods, and its 
surmounting filament, I have searched most diligently, 
indeed I may almost say wishfully, as desiring to see what two 
such authorities have described as the true form, but I must 
confess to have failed. True, a short conical appearance is 
often to be seen at one or other extremity of the rod, but I 
have never been able to satisfy myself that it is not an optical 
effect, from the end not being in focus, for almost invariably 
I have found that by focusing the conical appearance disap- 
pears, when the rods are single, and while they are in situ ; 
supposing them to be conical, and the cone enclosed in a 
sheath of the choroid, I do not see how it is to be observed, 
at least I have failed in the fresh eye, and so distorted do 
these smali bodies become by drying the retina, and subse- 
quently moistening it, or by the addition of any reagents, 
that I place very little reliance upon appearance then pre- 
sented; nor do I think the statement of these observers, that 
the great disposition there is for the rod to break at the pre- 
cise point where it becomes conical, is sufficient to account 
for the difficulty of finding the cone; for in this case the 
cones ought to be found separate in some abundance, consi- 
dering the enormous multitude of rods; which they are not. 
Besides which, while they state that the inner end of the rod 
is perfectly straight, and the outer is conical and pointed, im- 
bedded in the choroid, Hassall describes the outer ends of 
the rods as of a globular or oval shape, and Kollker declares 
the opinion of the conical form of the outer end to be a mis- 
take—that, in reality, it is perfectly flat and straight, while 
the inner end is not only conical, but sends a filament so 
prolonged as to pass entirely through the outer layers of the 
retina to the inner surface, where it terminates in radiating 
fibres as first described by H. Miller. Kolliker would ap- 
pear to regard the rods as cells filled with fluid, for he says, 
that on breaking up, “ they allow clear drops to exude, which 
are often met with on the external surface of the retina in 
vast quantity.’ This is contrary to the observations of most 
others, and does not correspond with what the rods appear 
to my eye, as above stated. By some the rods are described 
as cylinders, terminating in an expanded head like a nail; 
very often rods may be seen of this shape. I have seen this 
particularly in the rat ; but it simply arises from the granule 
to which the inner end of the rod is attached still adhering to 
it; by watching for a while, it will be seen to become de- 
tached ; often too they appear conical or swelled out, from a 
granule adhering to some other part of them. 

In all birds, and in the turtle, the straight cylindrical rods 


NUNNELEY, ON THIS RETINA. 223 


are comparatively few in number, the greater part of them 
are conoidal or fusiform in shape, the base being without, 
and they are surmounted by a highly transparent coloured 
globule, which is clesely attached to and partly imbedded in 
the end of the rod. The number of the true cylindrical rods 
in aquatic birds, as the duck, goose, or swan, appears to be 
very much less than in land-birds; indeed, in some it is 
questionable if all the rods are not more or less conoidal in 
shape, but they are so to a less extent than are those of land- 
birds. The globules are evidently cells filled with a coloured 
fluid, which reflects light almost like oil, but is not oil; for 
the cells are not soluble in either spirit of wine, or dilute 
potash, ammonia, acetic or chromic acids; and when the 
globules are crushed, and the coloured fluid has run together 
and dried, it is soluble in water, while the dried globule, by 
immersion in water, swells out to even a greater than its 
normal size. They are unaffected by immersion in boiling 
water; they are well seen by the addition of chromic acid ; 
and then, if liq. potassee be added, the colour is destroyed, 
but their shape and size are well shown; the rods are dis- 
solved, and thus they are left free. Many of the globules are 
of a beautiful ruby red; others, and the greater number, 
three or four to one, of a canary yellow, some approaching to 
a green tinge ; some few I have seen of a decided green colour, 
and in some the colour is so pale, as to be hardly perceptible. 
Though the yellow are the most numerous, the ruby are for the 
most part the largest. There is no fixed relation either in 
number or size, nor are those of the same colour always of the 
same size, varying in the bird from 5,'55 to psboo of an inch; 
and I think the size, number, and relative proportion 
of the two colours differ in different parts of the same 
retina. In a guinea fowl, I found the globules very nearly 
uniform in size, about the 5-55, of an imch, and the 
globules of pretty nearly the same tints of ruby and canary 
colours. I have found there is more variation in size and 
colour of the globules in young fowls than in old. Though 
closely imbedded in the rods, they easily become detached 
and float about; they are also attached to the choroid coat, 
but not so intimately as to the retina, for in separating it 
from the retina they always adhere to the latter. They are 
much more persistent than most of the other elements of the 
retina, and may be preserved, when dry, for some time. 
Hannover, who was the first to describe these bodies, has 
fizured the ruby as attached to what he calls cones jumeaua, 
and each of these as surrounded by six rods, surmounted 
each by a yellow globule, forming a setting for the ruby. I 


224 NUNNELEY, ON THE RETINA. 


do not think any such precise relation in number or position 
exists. 

I know of no more beautiful object under the microscope 
than the outer surface of the retina of a Cochin cock, guinea 
fowl, or turkey, and particularly of a turtle. Could a lady 
deck herself in jewels so brilhant and beautiful, she would 
esteem herself the gayest in a ball-room. I know of nothing 
except the corneal facets of a coleoptera to compare with it. 
In some birds the colours are much more intense than in 
others. I thought it possible the colour of the feathers 
might have some connexion with this, but it does not ap- 
pear to have; for instance, the yellow globules of the canary 
bird are not more numerous or intense than those in the 
sparrow; the ruby in the brilliant game cock than in the 
gray guinea fowl: nor does there appear to be any difference 
in two similar birds of different plumages, as in a white and a 
variegated fowl. However, I do not think, in aquatic birds, 
they are so brilhant m tint as in land-birds, nor is there 
altogether so much difference in the size of the two-coloured 
globules. But, of all creatures which I have examined, the 
coloured globules are the largest and most distinct in the 
green turtle. ‘The ruby are, as in birds as a whole, larger 
than the yellow, and are more uniform in colour; whereas 
the tint of the yellow, like their size, varies very much, from 
a full canary, to nearly or completely colourless white. 

Similar, but not nearly so perfect globules, are found in 
some other reptiles. I have seen them in the toad and the 
frog; in the latter of which they are most distinct; and in 
some fish, the eel for mstance, globules of the same general 
size and appearance, but of a brown colour, more like those 
of the choroid, but larger, are to be found. So in some mam- 
malia brown globules of the same size and general characters 
are to be sometimes sparingly met with. In viewing these 
coloured cells they often appear as containing-a circular 
nucleus, which is, however, only an optical effect, for by 
adjusting the focus it always disappears. Hannover describes 
this appearance as resulting from the cells bemg conoidal, 
and both ends being seen at the same time. In some few 
eases I have thought the detached cells conoidal, but this is 
so very rare compared with the frequency in which no doubt 
can exist of the generally perfectly globular character of 
both ruby and yellow cells, that I rather incline to attri- 
bute it to the end of the rod in which the cell is partially 
imbedded being seen, than to the cause mentioned by 
Hannover. In one bird, the common fowl I believe, the 
globules had a short projecting spur, which was received into 


NUNNELEY, ON THE RETINA. 229 


the end of the rod, and which might give rise to the appear- 
ance; and in the turtle I have seen a few of the globules 
with a similar minute projection on one side, as though it 
had been imbedded in the conical rod; in the swan, where 
the globules are not particularly well developed, I have found 
some few fusiform in shape. 

The use of these globules I can offer no conjecture upon. 

Internally the rods pass in amongst the granules, and the 
end of each rod appears to rest upon and be connected with 
one or more granules. Externally the end of the rod is, I 
think, implanted upon the cellular or epithelial, as it has 
properly been called, layer of the choroid; the clear portion, 
which has been regarded as the choroidal cell, being that 
where the rods have adhered; for there can, I think, be no 
doubt that the retina and choroid are organically connected 
together, the rods probably deriving their nutriment from 
the choroidal vessels ; no blood-vessels are to be found in the 
columnar layer itself. 

The rods are evidently a nervous structure, sui generis, 
their whole appearance indicates this, and probably they are 
intimately connected with the sense of vision; but in what 
way they act, whether as independently perceiving the image, 
which the nervous fibres only place in relation with the 
sensorium, which then intelligibly appreciates the informa- 
tion, or only as affording a suitable surface for the im- 
printing the image upon, which the nerve-fibres then convey 
to the sensorium to be there perceived, it is premature to 
discuss; but their complex character would rather point to 
their possessing some independent function, than to their 
being the mere recipient surface for an image, to be thence 
conveyed to the brain as the sole sentient part. Whether 
they are the real terminal expanse of the optic fibres, as 
Kolliker seems to suppose that Miiller’s and his own 
observations indicate, is, to say the least, unproved; nor 
does it appear to be necessary for our estimate of the im- 
portance of their functions. That they are in connexion 
direct or indirect is more than probable, but that they are to 
be regarded as the expanded nerve-ends does not seem so 
probable as their being peculiar nervous structures, having 
separate and individual power. Where there is the greatest 
amount of intelligence they appear to be the smallest and 
most numerous. 

This is the structure which was first pointed out as a 
distinct layer of the retina by Dr. Jacob, and has since been 
known as the membrane of Jacob; though its nature was 
not, indeed could not have been, known by him. He 

VOL. VI. a 


226 NUNNELEY, ON THE RETINA. 


regarded it as a protecting membrane, imterposed between 
the nervous retina and the choroid. This notion became 
commonly adopted, and was much extended by other anato- 
mists, some of whom, particularly the late Mr. Dalrymple, 
argued very strenuously for its being a true serous membrane, 
constituting a shut sac like the pleura or arachnoid, a view 
he supported by arguments, drawn from analogy and patho- 
logical conditions, which he thought satisfactory. Of course, 
now that its structure is so far known, this idea must be 
altogether dismissed. It is most easily detached in trans- 
lucent shreds from the other elements of the retina as soon 
as decomposition begins, or on immersion in water. When 
this occurs it is evident that the structure has undergone a 
change ; the rods are then altered. (Plate X, fig. 3.) 

2. The cones or bulbs constitute the second layer of the 
retina; however, as these bodies when found are always placed 
amongst the rods towards their inner end, they are hardly to 
be considered as forming a distinct layer, though for con- 
venience of description it is necessary to speak of them 
separately. Regarding them there is even more difficulty 
and uncertainty than with the rods. As to the latter no one 
can doubt their existence in the whole of the vertebrate 
division, whatever differences of opinion may be entertained 
as to their form and connexion, but the very existence of the 
bulbs, in by far the greater number of animals, is open to 
considerable doubt; and of their form, number, and con- 
nexion, to much more. Hannover, who has given the most 
elaborate description and figures of them, from their form, 
denominates them cones jumeaux, coni gemini—twin cones, 
and says they consist in the fish, where they are most 
developed, of double cylindrical bodies, two or three times as 
large as the rods, placed side by side: that each of these 
cylinders is divided into two equal parts; an internal one, 
smooth and round, as though enclosed in a delicate capsule, 
separated from the external half by two transverse lines ; 
and an external moiety, composed of a mass of minute 
granules, and terminating outwardly in two conical points. 
That after a time, or on the addition of a liquid, the inner 
cylindrical portion becomes larger and fusiform, bilobate like 
a coffee-berry and granular, while the conical points fall off, 
curve themselves into hooks, and often altogether disappear. 
That the cones jumeauex, like the rods, are planted perpen- 
dicularly to the other elements of the retina and choroid, 
that each cone jumeau is completely surrounded by a regular 
number of the rods, and that each of the two conical points 
is, like the filaments of the rods, received into a membranous 


NUNNELEY, ON THE RETINA. 227 


sheath of the choroid, as the corolla of a tubular-shaped 
flower is surrounded by its calyx, but that the sheath without 
colour in reality encloses the entire cone. That the cones 
are wanting in all reptiles except the chelonian. 

In birds Hannover considers bodies very different in form 
as the cones jumeaux (those which I have called conoidal or 
fusiform rods); because they are sometimes surmounted by 
two coloured globules and are surrounded by the rods. He 
states, as already mentioned, that the citrine-coloured 
globules are situated at the outer end of these cones.* In 
mammalia he describes the cones jumeaux as being shorter 
than the rods, with their external ends terminating in two 
short and abrupt points. 

Mr. Bowman was the first to describe the bulbs in the 
human retina. He says they are solitary, globular, or egg- 
shaped, transparent bodies, sometimes having a small blunt 
spur upon them, turned towards the choroid, placed at 
regular intervals amongst the rods, much less numerous than 
the rods, of larger size, but not so long, and sessile upon the 
granules. Unlike Hannover, who believes these bodies not 
to exist in reptiles except the chelonian, Mr. Bowman thinks 
they not only do exist, but that in the frog they are nearly 
as numerous as the rods. 

Hassall, in his description of the microscopic anatomy of 
the eye, makes no allusion to the existence of such bodies as 
cones or bulbs, which evidently he had not detected. 

KOlliker’s figures and descriptions of the cones are al- 
together at variance with those of both Hannover and. 
Bowman. He states that the cones are rods, which instead 
of a filament at their inner extremity, are furnished with a 
conical or pyriform body. That each cone consists of an 
external, thicker and longer finely granular extremity, more 
or less ventricose, and which passes into a common rod ; and. 
an inner, shorter portion, in which an elongated or pyriform, 
more opaque and brilliant body, is enclosed ; the cones being, 
like the rods, continued by fine filaments into the deeper 
layers of the retina. 

I have searched most carefully for these bodies in the eyes 
of many animals, but I cannot say that I have satisfied my- 
self of the existence of any bodies such as have been 
described in the perfectly fresh eyes of any creature, except 


* In the text Hannover states that the cones jumeaur are surmounted 
by. the citrine-coloured globules, while in his figures of these parts, and in 
the description of them, he represents the cones as surmounted by the 
ruby-coloured globules. (‘Recherchés microscopiques sur le Systéme 
nerveux. ) ; 


228 NUNNELEY, ON THE RETINA. 


fish, and even here, they do not, so far as I can ascertain, 
exactly correspond with the description given by Hannover ; 
and in the turtle, where the bulb is distinct. In sections of 
retina from the higher animals, which have been dried and 
moistened by various reagents, or even fresh retina treated 
with dilute chromic or acetic acids, it is not difficult to find 
various-shaped particles, which may be supposed to be these 
bodies, but inasmuch as they are not to be detected, so far 
as I can ascertain, in the perfectly fresh eye where its retina 
alone is examined, I am doubtful of their actual existence 
as distinct bodies. There is no difficulty whatever, when 
regarding the undisturbed external surface of the retina of 
either reptiles or mammalia, of recognising the forms figured 
by Hannover and Bowman, which they consider the cones 
or bulbs not in focus, but I have always failed in detecting 
the appearances represented by them im profile, and I am 
more inclined to think the bodies seen at a deeper level, and 
out of focus, when the outer ends of the rods are in focus, 
not as cones or bulbs, but as the outer portions of the 
granular layer to be presently described, and upon which the 
ends of the rods rest, indeed are closely attached to; or as 
the inner ends of the rods themselves, not in focus. 

That coffee-shaped granular bodies, often more or less 
bilobated, are to be seen in the retina of many animals is 
certain, but I have so commonly seen rods to assume this 
form while under the microscope, that I strongly suspect 
many of the forms which have been described as cones are 
really only modified rods. That bodies at all resembling 
the cones jumeaux of fish, which may be regarded as the 
type of these cones, exist in mammalia or most reptiles, I 
am persuaded is incorrect. I have examined the eyes of the 
alligator, the chameleon, the newt, the frog, and toad, the 
last three over and over again, both young and old, fresh and 
dried eyes, without being able to detect any. Moreover, 
Hannover’s own account of what he calls these bodies in 
birds shows them to be altogether different structures from 
what he describes under the same name in fish. In birds 
there are, as has already been stated, numerous conoidal 
bodies surmounted by a brilliant coloured globule, but they 
appear to differ very little from rods, and their broader end 
is external, while they are in no respect double, nor have 
they any sharp conical points, either single or double.* 


* To describe bodies which differ so esscntially as the cones jumeaur of 
fish, and the elongated bodies which are surmounted by a coloured globule 
in birds, as the same structures, appears rather as a predetermination to 
find an uniformity of structures, than a simple representation of what 


NUNNELEY, ON THE RETINA. 229 


In fish there certainly exist imbedded between the deeper 
ends of the rods, and like them, resting upon the granular 
layer, a number of conoidal bodies of larger diameter than 
the rods; each consists of two portions; an oval bulbous 
part when two are pressed together, globular when they are 
single ; and a conical one of about equal length. The point 
of junciion is marked by a very fine transverse line, and where, 
commonly, but not invariably, a separation takes place. They 
reflect the light strongly, and are at first perfectly trans- 
parent, solid, and homogeneous. The conical end breaks up 
into discs, and then granules, exactly like the rods, while the 
bulb swells and becomes less transparent, then granular, often 
irregular in shape, not unfrequently it splits more or less 
completely into two portions, and then disappears in granules. 
When the conical leg has become detached and the bulb 
somewhat split, it resembles much a coffee-berry. These 
changes occur within a very short time after death. I have 
seen them take place while the part was under examination, 
within fifteen minutes after the fish had been swimming in 
the water. They occur immediately on the addition of water, 
and many other reagents. These cones lie with the bulbous end 
resting upon, and connected with, one or more granules, the 
narrow end always being outwards. They are closely con- 
nected with the rods. There does not appear to me to be 
any such regular relation in number and arrangement between 
them and the rods as is described by Hannover ; they often 
are solitary, but very commonly two are side by side, when 
they may closely adhere by their sides, which are flattened as 
by pressure, and which has probably given rise to the idea 
of their being double, but they may be separated without 
any division of structure in the greater number of fish, though 

erhaps not in all. The cones are, I believe, commonly 
single, and 1 do not think they are enclosed by any sheath 
from the choroid; indeed, in some fish they do not appear to 
reach the outer surface of the retina, being shorter than the 
rods, as in the golden carp; while in others they are quite as 
long or even longer, asin the cod and whiting. The relative 
proportion of them and the rods appears to differ in different 
fish. In the sand-dab, Platessa limanda, and the Ballen- 
wrasse, Labius maculatus the cones are comparatively few; 
while in the whiting, Merlangus vulgaris, and the little 
weaver, or venom fish, Trachinus vipera, they are much more 
numerous ; in the mackerel, Scomber scomber, they are very 
really is seen—an attempt to generalise than a record of what actually 


exists—the small ovoid bodies more resemble the coves jumeaux of fish than 
do the conoidal rods. 


230 NUNNELEY, ON THE RETINA. 


large. In some portions of the same retina they also appear 
more plentiful than in others, and in some fish, as the golden 
carp, Cyprinus auratus, the venom fish, and the cod, they ap-. 
pear more distinctly as single bulbous bodies, often two lying 
close together, having each a singleconicalprojecting part; while 
in others, as the whiting, the bulb more commonly appears as 
single at first, with two conical ‘projecting parts, and subse- 
quently to split into two portions. The conical portion very 
closely resembles in character the rods, while the bulbous 
part more nearly approaches the granules. Can they be re- 
garded as rods in the process of development? By water 
they are immediately broken up; by ether much distorted, 
and then destroyed ; by ammonia they are instantly (as are 
the rods) dissolved ; by acetic acid they are also destroyed, and 
only a clear globule left. Chromic acid also acts upon them, 
if strong it distorts them much, if dilute it acts as water; 
acetic acid has a similar action. 

The retina of the turtle, if examined instantly the animal 
is killed (for like all others it changes in few hours), is a very 
interesting sight. The outer surface is composed of conoidal 
rods, in shape very like those of a bird, and lke them 
surmounted by brilliantly coloured globules, partially im- 
bedded in the rods. These rods are of large size with the nar- 
row portion inwards, and between them lie a number of oval 
bodies, which are clearly the bulbs of Bowman. They do not 
reach the outer surface of the retina; they are clear, trans- 
parent bodies, exactly in texture like the conoidal rods, and 
hike them, after the lapse of a short time, or immediately on 
the addition of almost any substance, becoming granular. 
There are also to be seen a great number of ovoid bodies of 
nearly the same size as the bulbs, surmounted by coloured 
globules like the conical rods; whether these are bulbs with 
coloured globules attached, or whether they are altered rods, 
with the inner narrow part detached, I am not able to satisfy 
myself, but I incline to the latter opinion, for they cannot be 
seen tn situ; and certainly in many instances, the conoidal 
rod appears with the outer part swelled out into a granular 
bulb, while the inner part is detached and breaks up into 
small discs and granules before disappearing, but, on the 
other hand, the end of many of the bulbs as they float about 
appears perfect. They carry ruby and canary coloured glo- 
bules of various sizes indifferently. I have never seen two 
globules attached to either one rod or one bulb (as Hannover 
says occurs), but I have often seen a loose coloured globule 
accidentally become attached, or the globules of two neigh- 
bouring bodies so lying as to require great care to distinguish 


NUNNELEY, ON THE RETINA. 231 


as belonging to two different bodies. There are a few cylin- 
drical rods, some of these are long and narrow, and appear to 
lie intermingled with the conoidal rods, while there are more 
which are shorter and thicker, and appear to be the inner 
ends of the altered conoidal rods broken off, and would thus 
resemble the conical portion of the cones jumeaux of fish— 
except that in fish the ends certainly are external, while in 
the turtle these portions as certainly he internally; and in 
fish the bulb breaks longitudinally into a coffee-berry shape, 
in the turtle it does not. There are few of the larger granular 
cells in the turtle as in fish; but the inner finely granular 
layer of cells is seen, as are the nerve fibres. (See Pl. X, 
where these bodies in the natural and altered condition are 
shown.) 

3. The granular, as it is called, forms the third layer of 
the retina. The name is not a very correct one, for these 
bodies are certainly not granules, as they have been described, 
but are cells filled with highly refractive, solid, granular nuclei. 
The walls are so thin and easily ruptured, that, after a time, or 
when reagents are applied, or insufficient power is employed, 
only granular matter is to be found; but when a perfectly fresh 
eye is examined with an eighth glass, or still better a twelfth 
and an achromatic condenser (see Pl. X,) not the least 
doubt can be felt as to their being cells filled with granules. 
They are usually irregular in outline, probably from com- 
pression against each other. They are found in all animals 
who possess a retina, but very far less in number in fish and 
reptiles than in man and mammalia, where they exist in 
enormous multitudes. They appear of pretty much the same 
size and character in most animals as seen on the slide by 
transmitted light. They are ofa pale yellow colour, and re- 
fract the light strongly like oil, their size varies considerably, 
some measuring z355, while many are not nearly half this 
size, some not more thanz5;55 of an inch. They bear a 
strong resemblance to, and are probably identical with, the 
cells found in the cineritious matter of the cerebral convolu- 
tions. They lie between the rods, which rest upon their 
outer surface, and the fibres of the optic nerve, and con- 
stitute in mammalia a considerable portion of the thickness 
of the retina, though not so much as the rods do. 

Bowman and Kolliker, both describe the granules as con- 
sisting of two layers, separated from each other by an indis- 
tinct fibrous layer, the outer of the layers being the thickest; 
but they are opposed to each other as to the size and shape 
of the globules forming them. Thus Bowman describes the 
granules forming the inner layer as smaller than the outer, 


232 NUNNELEY, ON THK. RETINA. 


of a flattened form, like pieces of money (hence named by 
him nummular layer), with the flat surfaces corresponding with 
the thickness of the retina; while Kolliker says the inner 
are larger than the granules of the outer layer, and arranged 
with their long axes in the direction of the thickness of the 
retina. Ifa section of the dried retina of man, the sheep, or 
the ox, be examined with water or dilute spirit, there is 
no difficulty in perceiving this irregular line of very minute 
granular matter and indistinct fibres with flattened globules 
arranged horizontally in the length of the retina, as described 
by Bowman, and not vertically in the direction of the thick- 
ness, as figured by Kolliker; but it is by no means so easy to 
detect this separation into two layers in the perfectly fresh 
retina. I have sometimes fancied it was to be seen in the 
bullock and sheep, but I have so often not been able to find 
it, that, knowing how greatly every portion of the retina is 
changed by all fluids, and how little dependence is to be 
placed im appearances there found, I feel doubtful if there 
really be two layers. The globules placed most internally 
are smaller than the external. It is, I think, in the inner- 
most part of this and the next layer that the capillaries of the 
blood-vessels are principally situated, though Bowman says, 
they have no blood-vessels, and certainly none appear to be dis- 
tributed in the mass or thickness of the layer. On the addition 
of water and many other fluids, the globules separate from 
each other, float about, dilate, rupture, and disappear, leaving 
only fine granules, which also dissolve. They are rendered 
more distinct and refractive by dilute acetic and chromic 
acids, in which they are well seen. 

The rods rest upon and are imbedded amongst them, each 
rod being intimately connected with one globule, which often 
remains attached to the end of the rod when the rods are 
detached from each other. This has given rise to the im- 
pression of the rod having a head like a nail, but in a few 
minutes it usually becomes detached, and is then seen to 
resemble the other globules. It may be doubted how far 
the connexion is organic or not, as the same globule may be 
seen, 1f it happen to come in contact with another rod, to 
adhere to any part of its surface. 

4. On the inner surface of the granular or nuclear layer 
is the vesicular layer—“ gray vesicular matter of retina’”— 
“ cineritious cerebral substance,” which is a very thin layer, 
composed of finely granular or cellular matter, of apparently 
the same nature as the last, and probably more correctly to 
be regarded as its commencing portion than as a distinct 
structure, in which also are numerous larger and clear trans- 


NUNNELEY, ON THE RETINA. 233 


parent cells with large eccentric nuclei and nucleoli, identical 
with those found in the cerebral convolutions. It is very 
difficult to see these brain-cells in situ in the fresh eye, but 
floating about they are readily seen; and in a successful 
examination they may be seen forming a layer in which the 
fibres of the optic nerve are imbedded and expanded. Plate X. 

In this layer, Bowman, Kélliker, and Hassall all describe, 
as being found, besides the circular brain-cells, caudate gan- 
glionic cells. Hassell says only to be found in man; Bow- 
man in man and the horse, amongst mammalia, but parti- 
cularly well developed in the turtle; while Kolliker figures 
those from the ox with very long processes, and his descrip- 
tion would inferentially lead to the supposition of their being 
generally distributed. Bowman says they do not contain any 
pigment, while Hassall represents them as altogether dark, 
and Kolliker as containing pigment in the body of the cells, 
with the large central nucleus transparent. Hannover, in 
his elaborate account of the retina, makes no allusion to any 
such cells, yet he was perfectly familiar with the character of 
caudate nerve-cells, for he has figured them as seen in dif- 
ferent parts of the brain and spinal marrow, and therefore 
we may conclude he either had not found them or does not 
believe in their existence. 

I have searched most carefully, over and over again, for 
these long caudate cells in the eyes of man, many mammalia, 
various birds, reptiles, and fish, and particularly in the almost 
living eye of the turtle, and must confess, ike Hannover, have 
failed to find them in the perfectly recent eyes. When reagents 
are employed, when the retina has been dried and moistened 
with water, or the retina examined is not from an animal just 
dead, not the same difficulty exists; large, irregular, more 
or less caudiform celis are then abundant enough. I am 
therefore, unwilling as I am not to see what such competent 
observers speak unhesitatingly of, constrained to doubt if 
cells such as figured and described, with many long caudate 
processes, continuous with the nerve-fibres, do really exist in 
the living eye. 

There are, however, constantly found, particularly in the 
eyes of mammalia, cells of various sizes ; some large, very much 
resembling in form, only perfectly transparent, epithelial cells. 
They are tiat, irregular, contain nuclei and fine granules, le 
singly or in groups overlapping each other, and are in con- 
nexion with, if not imbedded in, as I believe, the granular 
layer, which they so much resemble, that unless caught de- 
tached from it, at first, until the eye is familiar with their 
indistinct outline, they are very difficult to recognise. I give 
figures of these cells from the retina of the human feetus, the 


234 NUNNELEY, ON THE RETINA. 


pig, the ox, and the sheep, all just dead. (Pl. X, fig. 7.) They 
are, probably, in composition, similar to the granular cells, and 
like them break up and disappear. There is, certainly, no 
pigment matter in them; and whether they are the cells 
described by Bowman, Kélliker, and Hassall as the caudate 
ganglionic, I am uncertain, but believe them to be. In 
which case, either I am wrong in being unable to see the 
prolongations, or the cells described by them are modifica- 
tions produced by the reagent employed, which I am in- 
clined to suspect to be the case, seeing that I have often 
found the angles much prolonged when reagents, particularly 
chromic acid, have been employed. 

5. The fibrous layer is composed of the filaments of the 
optic nerve. This nerve, which consists of nerve-tubes and 
cerebral cells, enters the ball of the eye through the eribri- 
form plate of the sclerotic coat, with which the fibrous sheath 
of the nerve- fibres becomes confounded, and then through a 
narrow single aperture in the choroid coat, which is closely, 
but not organically, connected to the nerve. This entrance 
varies in its relative situation in different animals; in man, 
being to the inner side, and below the axis of the ball. The 
nerve here forms a slight mammillary projection, in the 
middle of which the central artery of the retina is seen. 
From this spot the nerve-fibres expand in every direction, 
forming a complete layer upon the outer surface of the 
hyaloid membrane. 

The fibres pass as far forwards as the ora serrata, but as 
yet the exact mode in which they terminate is unknown ; 
some observers have asserted that they form loops and return 
upon themselves, others that they are lost in the other ele- 
ments; but I believe no one has demonstrated their termi- 
nation. My own impression is, that these fibres are of 
different lengths, and successively terminate as they pass 
forwards, by being lost or continuated into the true retinal 
elements, the granules being the connecting medium between 
the nerve-fibres and the rods: and that the number of the 
fibres at the anterior part of the retina is much less than at 
the posterior, not merely because in forming a continuous 
expansion over a larger area necessarily there must be fewer 
fibres in any given space than there is in the smaller, but 
because the fibres are continually terminating, so that they 
are really fewer in number in the anterior than in the pos- 
terior part of the retina. * 

The fibres lie to the inner side of the granular layer, which 

* Instead of speaking of the fibres as terminating in any of the retinal 


elements, it would doubtless be more correct to speak of them as arising 
from or being continuous with them, the optic being an afferent nerve. 


NUNNELKY, ON THE RETINA. 235 


separates them from the rods, and they are, as it were, im- 
bedded in the vesicular layer, which, without care, always 
renders the fibres indistinct. These may be seen in man, 
animals, birds, reptiles, and fish, on both sides of the fibres. 
(See Pls. X and XI.) 

Much discrepancy of opinion prevails as to the exact 
nature of these fibres. Hassall and Bowman assert that 
they are flattened solid fibres of gray matter, not tubular, 
the white nerve-matter ceasing as the nerve passes through 
the sclerotic coat, or almost immediately after it has entered 
the eye, and that in passing forwards they anastomose, so 
as to form elongated meshes, in which nucleated vesicles 
appear. Hannover states that the fibres in the retina appear 
to possess greater consistency than they do in the trunk of 
the nerve itself, but otherwise have the same character. That 
they proceed forwards in straight lines, without subdividing 
or anastomosing, and never become varicose. (The latter 
statement he modifies in a note, and allows that they do, 
when not in a natural state, become varicose.) Kolliker 
says, each fibre enters the eye without its sheath of con- 
nective tissue, independent of the others ; that, radiating in 
all directions, they constitute a continuous membrane as far 
forwards as the ora serrata, running parallel to each other, 
or inosculating at very acute angles, are without nuclei, and 
form frequent varicosities. He styles them the horizontal 
fibre system, in contradistinction to the rods and cones, 
which he calls the radiating fibre system. My own observa- 
tions agree more nearly with those of Hannover and Kolliker, 
than with Hassall and Bowman, though not exactly with 
either. If the formation of varicosities is to be regarded as 
showing the tubular character of nerve fibres, I can enter- 
tain no doubt that those of the retina are as much tubes as 
those in the optic nerve, with which I believe they are directly 
continuous, and also possess the same characters. I have 
seen the fibres in the retina in man, sheep, oxen, birds, rep- 
tiles, and fish become varicose while under examination ; 
the addition of a little water, dilute acetic acid, or mere 
variation in the pressure, will make them so at once, and often 
after being in weak spirit for a short time they are found so, 
particularly when the cerebral cells are gently removed 
before examination. When a particle of the optic nerve, and 
another of the retina, of perfectly fresh eyes of almost any 
mammal or fish, are examined with the assistance of either 
very dilute ammonia or chromic acid, it would be very diffi- 
cult to point out the difference in the fibres of the two; 
their size is the same; and with those from the retina, per- 
fectly clear cells with double walls, different from the nu- 


236 NUNNELEY, ON THE RETINA. 


cleated cerebral cells forming the fourth layer of the retina, 
but perfectly like those in the optic nerve, may be found. 
In the retina the fibres are somewhat wavyeas they pass 
forwards, they reflect the light strongly, and at times, though, 
I think, not very frequently, they ferm anastomoses with each 
other; or at any rate appear to do so, at long intervals, and 
at acute angles; and my impression is, they terminate in the 
granular layer, though this is by no means demonstrated. 

In the fish these fibres are larger than in mammalia, not 
so distinctly tubular, run straighter, are not seen to moscu- 
late, and do not, so far as I have observed, so readily become 
varicose, though they sometimes do, as in in the cod (PI. XI, 
fig. 10), altogether presenting more the character of gray 
fibres, without the white tissue, than in higher animals. The 
optic nerve projects further into the eye of fish than it does 
inthem. As the retinal fibres appear to me to be identical in 
structure with the nerve-fibres, so I believe them to be in 
function, and to merely convey the impressions to the senso- 
rium which the true retinal elements perceive. ‘This would 
satisfactorily explain why the part of the eyeball where the 
nerve enters it, and where only nerve-fibres exist, must neces- 
sarily be insensible to visual impressions. 

6. Hyaloidal cells—On the inner surface of the fibrous 
layer, interposed between it and the vitreous humour, is a layer 
of perfectly clear, transparent cells, having very thin walls, free 
from nuclei, but which after a time become very delicately gra- 
nular. Hassell describes them as situated on the outer surface 
of the fibrous layer, and thus in the texture of the retina, 
which is certainly wrong, while Bowman considers them as 
part of the hyaloid membrane. Whether they should be 
regarded as part of this or of the retina is doubtful, though, 
as they appear to be more intimately connected with it than 
with the hyaloid membrane, I incline to think them a part 
of it. They appear to be the medium of connexion between 
the two, and serve to organically unite them. When detached 
they are perfectly globular, but when én situ, and particularly 
when somewhat Ealan ged by imbibition, as they become if 
the eye be immersed in fluid for awhile, or by the action of 
its own fluids, they are irregular in outline and overlap each. 
other from disten sion. T hey appear to form a single layer 
of cells. Their size varies much in different animals, the 
size of the creature being no guide to the size of the cells. 
They, however, appear to bear some relation to the size of the 
rods and blood-discs, as these do to each other. They are larger 
in birds than in mammalia, the largest I ever saw being in 
the turkey and in a canary bird, (Pls. X and XI), ; aa these 
are probably enlarged by endosmose. 


NUNNELEY, ON THE RETINA. 237 


The retina is much more easily separated from the vitreous 
humour after a time than it is immediately after the death of 
the animal, which may arise from the change these cells 
undergo. 

7. Vascular layer.—The retina is a very vascular structure ; 
it is supplied by the central artery of the retina, which almost 
as soon as it enters the eye divides into two or three branches, 
which immediately subdivide and form a series of inoscula~ 
tions; the branches pass forwards and form a complete vascular 
network, until the vessels become capillary, which they do sud- 
denly from vessels of comparatively large size. At first the 
larger branches are on the inner side of the fibrous layer, but 
as they pass forwards they gradually penetrate this, some of 
the branches running parallel with the nerve fibres for a con- 
siderable distance, (Pl. X, fig. 4) ; but the smaller branches 
and capillaries, which form beautiful loops with each other, 
appear to be exclusively distributed in the vesicular and 
granular layers, on the outer surface of the fibrous, (Pl. XJ, 
fig. 7) ; none, so far as can be detected, passing into the 
bacillar layer. Many of them form terminal loops at some 
distance from the anterior termination of the retina, (Pl. XI, 
fig. 8). Near the ora serrata there is described to be a cir- 
cular vessel, into which many others pass; this is regarded 
by some anatomists as a vein. 

It is necessary in injecting these vessels to do so from the 
ophthalmic or carotid arteries ; but the larger branches are so 
commonly found congested after death, that they may be 
readily seen, and not unfrequently the smaller ones are so 
filled with blood, that.their minute ramifications may be 
examined with great facility, particularly where cerebral 
congestion has existed during life, or immediately after death 
the animal has been placed with the head in a depending 
position. (Pl. XI, fig. 7), is taken from the retina of a 
woman who died of cerebral congestion. In the other eye 
a small apoplectic clot was found, and several patches of con- 
voluted highly congested vessels. 

This communication has already occupied so much space, 
that I must reserve until another opportunity a description 
of the punctum centrale of Soémmerring. I append the size 
of the rods and granular cells in some mammalia, and of the 
rods, cones, and bulbs in some birds, reptiles, and fish, in 
parts of an English inch. I would, however, wish the mea- 
surement to be regarded as no more than an approximation 
to the absolute size of these bodies, which certainly differs 
in different parts of the same retina. 


NUNNELEY, ON THE RETINA. 


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VOL. VI. 


242 


On Triceratium and some New Aiiep Forms, with figures. 
of the same. By Surgeon G. C. Watticu, M. D., Bengal 
Army. (Plates Xi, Si: 


«Tir want of short characters,’ observes Professor Walker- 
Arnott, “ (intended to place clearly before the mind the few 
essential points of difference between supposed new and 
already known forms or species) cannot be supplied by figures 
or diffuse descriptions of the entire object, as these leave quite 
in the dark the precise marks of distinction observed by the 
writer, if such actually existed.” 

Toa certain extent this remark is true. But in the present 
state of our knowledge of that class of microscopic organisms 
to which Professor Walker-Arnott refers, its application 1s 
attended with so much difficulty, that, in the absence of 
somewhat detailed description, or accurate figures, the task 
of establishing clear views of special differences of structure 
becomes well nigh hopeless. Theoretically, it may be a 
matter of perfect simplicity to lay down definitions; and 
rules may be offered whereby, in the ordinary researches of 
natural history, such definitions shall be limited to a given 
number of words. But great obstacles present themselves in 
practice, where the microscope stands between the observer 
and the object he is analysing. ‘To describe clearly and con- 
cisely what is seen by the unaided vision, may be an easy 
matter; but, in the case of organisms visible only under a 
high magnifying power, and which demand an experienced 
eye for their interpretation, the case becomes very different. 
It is here that illustrations afford the greatest possible assist- 
ance, and frequently accomplish in a moment what would 
otherwise demand hours of anxious and tedious labour. Good 
definitions are indispensable ; but, under every circumstance, 
their value is much enhanced by well-executed figures. 

We see this exemplified strikingly in the ‘Synopsis of 
British Diatomaceze.’ Nothing can surpass the general con- 
ciseness of the definitions there given; but few will, I pre- 
sume, deny that a number of instances might readily be cited, 
where those definitions would fail to convey the clear com- 
prehension imparted by the masterly figures appended to 
them. 

There is another reason why accurate illustrations are of 
the highest value. As the number of new forms increases, and 
data are thus afforded for revising errors of classification, 


WALLICH, ON TRICERATIUM. 243 


those figures become landmarks, and th-ough them are 
afforded the means of ready comparison and reclassification. 

In no family, perhaps, is the remodelling of characters, and, 
in this particular ease, even of generic nam2, more necessary 
than in Triceratium. Recent additions to it clearly showing 
that outline, the character upon which it was originally, and, 
I may say, almost entirely, instituted by Ehrenberg, is not to 
be relied on; and that mere form may vary to a very great 
extent, whilst other characters, derived from important struc- 
tural analogies, at once point out how little value is, in reality, 
to be attached to it. Two of the species I am now about to 
describe exhibit this circumstance in a remarkable degree; 
the one a normally four-sided, the other a normally five- sided 
form; but both, nevertheless, distinct Triceraiia. 

The first of these, to which I propose giving the specific 
name of 7’. serratum, was obtained by me at St. Helena, 
along with numerous other new and highly interesting forms 
of living Diatoms, in dredging at oon twenty to thirty 
fathoms. Its characters are as follows 

Frustule free, constituting a ped prism. Valves 
quadrilateral, quadrangular—furnished with a_horn-like 
process at each angle ; and from four to six elongated spines 
furcate at their extremities. Connecting band composed of 
four quadrangular plates, joined together “by regularly ‘ dove- 
tailed”’ margins. These plates, in common with the valves 
_themselves, “marked with a delicate but well-defined hexa- 
gonal cellulation. 

This form is remarkable chiefly for the very peculiar struc- 
ture of its connecting membrane, which exhibits four distinct 
plates, having their communicating margins serrated, so as 
to fit into each other with accuracy. From this character the 
name is borrowed. The notches, or serre, are rectangular. 
Across each plate, during division, there is to be seen an 
arcuate narrow band, along which the cellulation is inter- 
rupted. ‘This band is expanded at its extremities. As divi- 
sion advances, each plate may be observed to consist of fwo 
layers, on the concave aspect of the arcuate band; which 
recede from each other; the upper one exhibiting the nor- 
mal cellulation ; whereas the lower (which is, in reality, a 
continuation of the other half of this plate) presents only a 
number of dots, the cellulation being imperfectly developed. 

In a memoir by Mr. Brightwell, “of Norwich, to which I 
shall again have occasion to refer, he mentions that the 
siliceous plates, forming the connecting membrane of the 
Triceratia generally, “are formed of several distinct layers 
of silex, dividing like the thin divisions of talc.” These 


244: WALLICH, ON TRICERATIUM. 


layers, I believe, with all deference to so deservedly high an 
authority, are, however, rarely more than two, and arise from 
the plates, during the commencement of division, in the frus- 
tules of this and many other genera, always consisting of two 
pieces, which, at first, entirely overlap each other; but, as 
the process advances, recede from each other, and whilst so 
receding, appear like three distinct parallel annuli, the centre 
being less diaphanous, and its markings more confused, in 
consequence of its being, in reality, the overlapping and 
double portion referred to. This appearance has led to much 
uncertainty and doubt in descriptions of the connecting mem- 
brane, inasmuch as, from its transparent structure, markings 
when they exist in the lower plates, are seen through those 
in the upper. In those genera in which the valves assume 
at times a great relative depth, we find not only that the 
connecting membrane is more largely developed, but that 
the valves are furnished with a constricted rim, to which the 
margin of the annular plate is attached, as if to afford a more 
powerful point of resistance from whence it can extend itself. 
In Amphitetras, and certain species of Triceratium and Bid- 
dulphia, the existence of marginal rows of puncta on the 
annulus, in close proximity to the markings on its surface 
generally, proves that the growth of each plate of the con- 
necting membrane takes place at the margin furthest off 
from the valve to which it is attached. Were it not so, the 
rows of marginal puncta would recede from the central mark- 
ings, an effect opposed to what in reality occurs. Growth 
thus takes place in both plates at once—the overlapping, to a 
greater or lesser extent, being dependent on the rate at which 
the new valves within happen to be developed. In the newly 
separated frustule, one end may constantly be seen imbedded 
in its own half of the connecting membrane, which, for a 
time, remains attached to it. The same structure exists, I 
believe, in nearly all the genera, although more readily discern- 
ible in some than in others, from the greater facilities they 
afford as regards size and figure. It may be thus seen in 
Mimantidium, Odontidum, Denticula, Eunotia, Grammatophora, 
Amphitetras, Biddulphia, Isthmia, Melosira, Coscinodiscus, 
Hydrosera, &c. I may observe, in passing, that the figures 
given in the ‘ Synopsis of British Diatomacee’ of Biddulphia, 
Amphitetras, and Isthmia, show the general aspect of the 
connecting membrane—but without any allusion, on the 
part of the author, to the striking mode of development now 
described. 

The arcuate bands are always arranged in the same direc- 
tion, that is, their concave or convex aspects always face 


WALLICH, ON TRICERATIUM. 245 


towards the same extremity of the frustule on all four sides. 
Valve slightly convex on its surface; cornua well defined, and 
projecting in both front and end views ; spines elongate, not 
marginally disposed; valve deeply constricted between the 
bases of the cornua and its free margin, which is everted ; 
connecting membrane projecting boldly. Length -0094; 
breadth ‘0063 ; diameter of each side of valve ‘0059 to ‘0070. 
Cellulation 9 to 11 in ‘001. Taking the characters given 
in the ‘ Synopsis’ as our guide, it would be more easy to recon- 
cile this form with Amp/hitetras than with Triceratium, inas- 
much as “the cubical outline,’ to quote the text, “ distin- 
guishes it from all other forms.” - But in Amphitetras, the 
frustules cohere into a zigzag filament ; the connecting mem- 
brane is imperfectly annulate and indefinite; the cellules are 
circular and inconspicuous at the angles of the valve. 
Whereas in the St. Helena species, the frustules never form 
a filament: the connecting membrane is definite and consists 
of four distinct plates; the cells on both the valves and con- 
necting bands are similarly marked with a conspicuous and 
regular hexagonal cellulation ; and lastly there exist the well- 
developed cornua and spines not seen in Amphitetras. 

Again, viewed as a Triceratium, the chief distinguishing 
type of that genus falls to the ground; for whilst the species 
under notice occurs abundantly in the locality named, in no 
instance has a three-sided frustule presented itself. There 
must be some limit to type, and therefore when the character 
fails, as it is here shown to do, upon which the individuality 
of a genus in a great measure rests, the alternative remains 
of either cancelling that character, or of separating the form 
in which so constant an anomaly exists. In this instance it 
must be borne in mind that the four-sided form is therefore 
the typical one, and yet that analogies of structure clearly 
indicate its position amongst the Triceratia. 

The nearest approach to its characters, I find in the 
‘Smithsonian Contributions, entitled ‘Notes of New Species 
and Localities of Microscopic Organisms,’ by Professor 
Bailey, of New York. A plate is there given of a frustule 
of Triceratium setigerum which, on a cursory examination, 
might be considered identical with the St. Helena Diatom. 
But, in the first place, it is to be inferred that the connecting 
band in that species offers no peculiarity, inasmuch as no 
allusion is made to such ; and, in the next, the characters given 
indicate its distinctness, the “bases,” as they are termed, 
‘being triangular, bearing three large obtuse projections or 
horns, at the base of each of which is placed a setiform 
process.” 


246 WALILICH, ON TRICURATIUM. 


Professor Bailey states that this form is allied to 7. spino- 
sum, which has been found in the fossil state in Virginia ; 
but the same reasons that s separates the St. Helena species 
from the Triceratia, of course apply equally to this. 

In the valuable paper on Triceraiium contributed to the 
‘Journal of Microscopical Science’ for July, 1856, by Mr. 
Brightwell, three forms demand notice as being at first sight 
allied to the one under discussion, namely, 7. sedigerum of 
Bailey, T. orbiculatum of Mr. Shadbolt, and T. formosum of 
Brightwell, the last being the 7. armatum of Mr. Roper. 

Before noticing Mr. Brightwell’s characters, 1 would draw 
your attention to a remark he makes on Professor Bailey 
having referred a four-sided form of Triceratium to the genus 
Amphitetr as, namely, that “the projection of a connecting 
membrane beyond the suture of the valve, which is one of 
the characters of Amphitetras, is not seen in these square 
forms.” A remark, if strictly accurate, at once fatal to any 
alliance between the St. Helena Diatom and those four-sided 
varieties, referred by Mr. Brightwell and others to the three- 
sided typical form. 

In a former paper on the same genus, in the ‘ Journal’ for 
July, 1853, Mr. Brightwell gives figures of three-, four-, and 
five-sided varieties of 7. striolatum, a name he alters in the 
recently published memoir into 7. formosum, already alluded 
to. Now in none of these does the connecting membrane 
project in the slightest degree. The colour of the frustule is 
moreover pale brown, indicative of very minute cellular struc- 
ture, whilst the horns are simple projections, and no spines 
exist on the surface of the valves; and lastly it is very much 
smaller than 7”. serratum. 

Amongst Mr. Brightwell’s species, 7. armatum comes 
nearer to the St. Helena form than any of the others. Mr. 
Roper, to whom we are indebted for a description of this 
species, thus characterises it in the ‘ Microscopical Journal’ 
for July, 1854: 

“ Frustules large, with straight or slightly convex sides. 
Angles produced into horn-like processes, with rounded ex- 
tremities ; cellular structure minute, partially radiating to- 
wards the sides and angles; six or more spurious processes 
projecting from the surface of the valve.” Mr. Roper’s 
specimens are described as approaching closely to 7. tri- 
daciylon, of Ehrenberg, a form also figured by Mr. Brightwell. 
But he states that 7. armatwn is deficient in the siliceous 
plate that is shown to exist around the sides of T. tridactylon. 
Mr. Roper thinks his specimens are not identical with Pro- 
fessor Bailey’s T. spinosum, whereas the spines are shown, 


WALLICH, ON TRICERATIUM. 247 


both in Mr. Roper’s and Mr. Brightwell’s figures, to be sub- 
marginal. 

Mr. Brightwell again figures several varieties of 7. armatum. 
The first being the only one that in the least resembles the 
St. Helena form. But his figure is represented as being the 
front view of that described by Mr. Roper, which has already 
been shown to be distinct, and is clearly proved to be so, 
from the other figure given of a front view of a four-sided 
specimen, in which the cells are circular; the connecting 
membrane is marked as in Amphitetras, and its margin ex- 
hibits a bold fimbriated border. 

The next form to which I shall refer is a very large and 
beautiful Triceratium, obtained by dredging at St. Helena, in 
form thirty-five to forty fathoms, and to which I propose to 
give the specific name of T. fimbriatum. 

Its characters are as follows : 

Frustule three-, rarely four-sided; sides convex; angles 
furnished with short cornua; cells large, hexagonal; mar- 
ginal border between horns furnished with a series of two- 
lobed flabelliform and pedunculated fimbriz; connecting 
membrane marked with diamond-shaped striation. 

The circlet of remarkable fimbrize at once serves to distin- 
guish this species. These arise from the outer edge of the 
marginal row of cells, by delicate pedicles, which immediately 
expand into broad filabelliform discs, having their flat 
surfaces parallel to the margin of the valve, and divided 
down their centre by a deep notch. These fimbriz are very 
similar in outline to the architectural decoration called “ Greek 
tiles,’ which are small separate mouldings, placed at intervals 
on the cornice of a building, along the side of the roof, and 
serve to conceal the ridge formed by the overlapping of the 
roof tiles. In some frustules there exist also, at each angle 
of each hexagonal cell, minute dot-like processes (recently 
figured by Mr. Roper as existing in Hupodiscus tesselatus), 
which, seen in profile when a portion of the valve is broken 
up, prove to be minute discs of similar character to the fimbriz 
just alluded to. 

This species has, however, another peculiarity which would 
render the specific name of favus especially applicable, had 
it not been already assigned to the typical species, to denote 
the similarity, in superficial aspect only, of the hexagonal 
markings to the honey-comb. Each hexagon in the St. 
Helen form being, not merely a simple depression dependent 
on the mode in which the siliceous element is secreted by the 
inner cell-membrane on its own surface, but a deep hollow 
cell, with perpendicular sides, of sufficient depth to be 


248 WALLICH, ON TRICERATIUM. 


readily measured, when seen in fragment and in profile; and 
which, a priori, indicates the presence throughout each cell of 
the membranous structure from which it is thus deposited. 
The floor of these cells is also minutely punctate, the puncta 
being arranged in quincunx.* The minute puncta only re- 
quire careful illumination and a power of 400 diameters to 
render them quite distinct. At first sight the double out- 
line visible in the hexagonal cells, as seen in certain positions, 
might be considered as due to refraction. But, on obtaining 
a fragment in an oblique position, the perspective view of 
the receding cells leaves no doubt of their true character. I 
would observe that similar cellulation appears to me to exist 
in other discoid forms, although too minute to be as readily 
interpreted. 

On a side view of the valve, below the outer series of cells, 
a single row of small rectangular markings is observable. 
The valve is slightly constricted around the margin. The 
horn-like processes are directed upwards, as in 7. favus, but 
do not project beyond the angles. The constant character of 
the outline of the valves in this species is remarkable, imas- 
much as it answers to the figure formed by describing an arc of 
a circle, with a radius equal to the magnified diameter of one 
side of the valve; taking off, on that are, the same radius, 
and describing a second and like are; and, lastly, making the 
point of intersection thus obtained the centre wherefrom to 
complete, with still the same radius, the third arc, or side of 
the figure required. 

The measurements are— 

Diameter of each side of valve, from ‘0047 to ‘0175; dia- 
meter of each cell ‘00034; cells 3$in°001; depth of hexagonal- 
cell-walls -00026; length of fimbriz :00046; breadth the 
same ; striation on connecting band 48 in ‘001. 

Although, m general character, this species is no doubt 
closely allied to 7. favus, the remarkable cell-structure and 
fimbriated border sufficiently distinguishes it. 

Mr. Brightwell, in the ‘ Journal of Microscopical Science’ 
for July, 1853, p. 249, describes a new species by the name 
of T. grande and to this a figure is appended which, in the 
end view, is very similar to T. fimbriatum. But T. grande 
has no border, whereas 7. comptum, also described and 


* This basal plate, when the valve is fractured, presents a remarkable 
and somewhat obscure feature, inasmuch as its line of fracture does not 
always correspond with that of the valve generally, and would thus appear 
in some measure distinct—a fact which I cannot help thinking has led to 


such lower plate in some of the discoid forms being looked upon as distinct 
species, 


WALLICH, ON TRICERATIUM. 249 


figured in the same place, under the sub-tribe with “angles 
spinose,” is much smaller, has nearly straight sides, but ex- 
hibits “a projecting fringe, stated to consist of oval depres- 
sions.’ Specimens of T. comptum in my possession, obtained 
from Californian guano, clearly correspond with Mr. Bright- 
well’s, and corroborate the distinctions from T. fimbriatum. 

Mr. Roper, in the Journal of the Society for July, 1854, 
p- 283, gives a figure also of T. comptum,'Ehr., which he 
states as having “a row of cells projecting above the margin 
of the valve ; sides straight or slightly convex, the horn-like 
processes short and obtuse; and cellular structure large.” 
But although Mr. Roper is doubtful whether his specimen 
may not be a young form of 7. favus, he leans to the opinion 
that the length of the angular processes and fringe-lke row 
of cells appear to give it a distinctive character. 

The next form is from brackish water in the Delta of the 
Ganges, and is undoubtedly new. I propose to call it 7. an- 
nulatum. The characters are—Valve minute, triangular ; 
angles slightly produced, rounded; sides shghtly concave ; 
tri-radiate, and having its surface covered with minute 
puncta; the more close aggregation of which, in concentric 
rings around the common centre, gives the valve an un- 
dulated appearance. 

The rays are thickenings of the siliceous epiderm which 
pass from the centre of the valve outwards in the direction 
of each angle, gradually becoming fainter as they approach 
the latter. In lke manner the puncta are more numerous 
and are more closely aggregated as they approach the central 
portion; whilst, at the extreme angles, the markings are 
almost entirely wanting. 

Diameter of each side -002. 

The next species, which I propose to call T. pentacrinus, 
although normally a five-sided form, is also distinctly refera- 
ble to that genus. It was obtained off St. Helena, in thirty 
fathoms water, in a living condition. The characters are 
as follows : 

Frustule free, constitutmg a pentangular prism; valves 
somewhat convex, pentangular, each side deeply convex ; with 
short stout cornua at each angle. Surface spinous; divided 
into compartments, by interrupted bands, which radiate 
irregularly from the centre, and inosculate laterally with 
each other. Cellular structure minute, consisting of circular 
dots. Connecting membrane annulate, indefinite, marked 
with dots arranged in quincunx, and which become more 
minute as they advance from the margin towards the median 
line of the annulus, and are partially interrupted at the 


250 WALLICH, ON TRICERATIUM. 


angles. Around the margin a row of oblong cells, placed 
side by side. 

The peculiar ribbed character here seen is conformable to 
that shown, in a modified degree, in several already described 
species. For instance, in the J uly number of the Society’s 
Journal for 1856, Mr. Brightwell characterises and figures 
no less than nine forms, all of which present the ribbed 
structure more or less. ‘To these markings, in some of the 
forms, Mr. Brightwell applies the term of “ canaliculi’? In 
the form under notice now, the ribs are, however, simple 
thickenings of the siliceous epiderm, which are neither 
tubular, nor dip down at all into the cavity of the frustule, 
so as to form pseudo-septa. The puncta are arranged im rows 
following the radiate direction of the ribbed partitions 
referred to. The horn-like processes appearmg more like 
inflated prolongations of the angles of the valve, the apices 
being minute and capitate. Valve constricted deeply between 
the bases of the horns and its margin. Spines numerous, 
irregularly placed, short and furcate. Connecting membrane 
projecting boldly, hyaline, with the undulating outline given 
by the form of valve, and its concave margins Anflecteds 

Diameter of frustule -0023; depth about -0020. 

T have met both with four- and six- angled varieties of this 
species; but these are rare. ‘The first is not unlike that 
figured by Mr. Shadbolt in the Society’s Journal for October, 
1853, p- 17; but as the front view is not given, it is 
difficult. to say positively whether the two are identical. 
Mr. Shadbolt describes his species as ‘‘ having the margins of 
the valves considerably hollowed out or emarginate, and 
folded over so that each valve is not unlike in form to a 
collegian’s cap. The surface being elegantly but somewhat 
irregularly ornamented with delicate markings.” 

Two remarkable Diatoms remain to be described in this 
paper, the characters of which, I believe, are essentially new. 
For although, at first sight, one of the species appears allied 
to the filamentous T7riceratia, its marked identity in structural 
peculiarities with the second, which is obviously distinct, 
leaves no reasonable doubt on the subject. 

Again, the second form, under a cursory examination, 
might be referred to Biddulphia, but its ‘unquestionable 
affinity, as I apprehend, to the first, would, with equal force, 
separate it from that genus. In both cases another and ver y 
conclusive example being afforded of the small real value 
that attaches to definitions based on mere outline. 

The species to which I allude were obtained by me from 
the Gangetic Sunderbunds, in brackish water, well within 


WALLICH, ON TRICERATIUM. 251 


influence of the tides; and were found growing attached as 

a soft mossy stratum upon submerged Alew or tree stems. 
Been the beautiful jointed-looking filaments, I have desig- 
nated the eee by the name of Hi ydrosera. The characters 
are as follows 

Frustules attached, forming elongated direct filaments. 
Frustules either triangular prisms or compressed cylinders, 
attached to each other at each angle by a mucous cushion. 
Valve cellular, furnished with perfect septa; and, on one side 
only, with a remarkable series of aperture-like appendages. 
Connecting membrane quite plain; hyaline. 

Although the association of the triangular with the com- 
pressed form may, at first sight, appear untenable, the 
other characters common to both, and more especially the 
remarkable processes observable on one side only of each 
valve, appear conclusively to establish the fact of their ranking 
under the same genus. The two species I have named 
respectively H. triquetra and H. compressa. 

The specifie characters of the first are as follows: Frustule 
athree-sided prism, having a portion of each angle partitioned 
off by a septate process, which is partly given off from the 
inner wall of the valve itself, and partly, as in Rhabdonema 
‘and Mastogloia, from the connecting membrane. Valve 
triangular, sides undulated, surface reticulated. Angles 
rounde d, obtuse, and smooth, but furnished with two or three 
stout minute spines. On one side only of each valve, at the 
central portion of its outer margin, from two to five minute 
punctate appendages exist. Connecting membrane compound, 
its outer annulus exhibiting a continuation of the valvular 
septa, plain, annulate and undulate. Front view of frustule 
a parallelogram, rather longer than broad when not under- 
going division. F.V. length, from ‘0017 to ‘0050 Breadth, 
the same. KE.V. diamicter: the same. Cellulation from 
Sto Ldn 001.. 

The punctate appendages are visible also in F.V. on both 
valves on same side of the frustule; and in the filament, on 
the same side throughout. Around them the siliceous 
epidermis thickened. Free ends of the septa of valve 
hollowed out, the cusps resting on imperfect septate pro- 
cesses given off from the connecting membrane. The outer 
margin of the latter much thickened, and giving to the 
F.V. the appearance of a siliceous hcop encircling the margin 
of each valve. Connecting membrane, of two plates or hoops, 
during division, as mentioned in Tuceratium. The spines at 
the angles very minute, and requiring careful illumination, 
with a power of from 300 to 400 diameters, to bring them 


252 WALLICH, ON TRICERATIUM. 


out clearly. They are probably of use in strengthening the - 
mucous cushion whereby the angles are held together; the 
filaments being remarkably tenacious. Frequently composed 
of from thirty to forty frustules. 

The frustules vary greatly in size, but never in general 
contour, although the sides are at times more inflated than 
at others. The side exhibiting the punctate processes being 
generally the most convex. In lke manner the angles are 
sometimes acute, sometimes subacute; an angular bend 
existing in the end view, where the septa coalesce with the 
margin. Cellular structure thickest at centre of valve, and 
varying to a limited extent in coarseness, although always 
large and easily seen in this species. Under a power of 200 
diameters, the marking seems minutely cellular; but ampli- 
fied to 400 diameters, it is shown to consist of a number of 
large reticulated polygonal spaces, having a tendency to the 
hexagonal character, and divided by narrow lines or ribs, 
which coalesce with each other. Entire frustule perfectly 
siliceous. Endochrome equally distributed, granular, and of a 
pale but rich green. 

In H. compressa the characters are : 

Frustule, a compressed cylinder, forming lengthened fila- 
ments, as in H. ¢triguetra. Valve elliptical, sides undulated. 
Angles subacute. Valve in E.V. divided into three compart- 
ments by two septa thrown across it. Angles smooth and 
occasionally exhibiting two or three very minute spines, as in 
the former species. ‘The punctate appendages on one side 
only. Connecting band plain, annulate, undulate, imdefi- 
nite. F.V. as in H. triqueira, a parallelogram, with subacute 
angles. 

In the front view the three compartments are inflated ; the 
central one being the largest. Ends full, rounded, and hyaline, 
with no trace of cellulation. 

F.V. Length of frustule, ‘0017 to 0048; breadth, :0017 
to ‘0048. §.V. length, from ‘0017 to :0048; breadth, -0006 
to ‘0014. E.V. length, from -0017 to ‘0048. Breadth of 
central compartment, ‘0017 to ‘0084. Breadth of terminal 
compartment, ‘00086 to ‘0014. ; 

It is difficult to suggest, with any approach to certainty, 
the purposes subserved by the unsymmetrically placed lateral 
processes alluded to. But, in all probability, they are ana- 
logues of the central and terminal nodules of other diatoms. 
On a future occasion, I hope to offer some remarks on the 
peculiarity they present, and to poimt out more particularly 
their resemblance to the unsymmetrically placed puncta in 
Gomphonema geminatum, and in two new Indian species of 


WALLICH, ON TRICERATIUM. 253 


Cocconema and Gomphonema, which are, in like manner 
distinguished by these remarkable appendages. 

The only genera with which Hydrosera can at all be con- 
founded, are—Terpsinoé of Ehrenberg, Anaulus of the same 
author, and Tetragramma of Professor Bailey ; the last being 
in reality, however, nothing more than a variety of Terpsinoé 
musica, and therefore not demanding further notice. 

In Terpsinoé the frustules are described as “ tabular and 
obsoletely stipitate,’ a character which might apply to 
H. compressa, but which at once fails in H. triquetra. The 
filaments, however, assume a “ zig zag”’ form, and the cellular 
structure is “ very minutely punctate,’ with no appearance of 
reticulation. 

I admit that it was a question resting chiefly on how far 
H. triquetra can be safely separated from [7. compressa, that 
induced one to remove the latter species from Terpsinoé, to 
which it bears a strong resemblance in its “tabular” or 
rather compressed form, but from which it differs materially 
in the presence of the lateral appendages, the spinous angles, 
and the direct nature of its filament. 

In Lithodesmium the valves are described as triangular, but 
they are distinguished from those of the present genus by 
their “extreme smoothness,” transparency, and their not 
being cellulate. Two sides only beimg symmetrical and 
“ undulated,” whilst the third “is doubly excised or notched.” 

Lastly, in Anaulus “the frustules never form a filament, but 
are single, and neither furnished with tubular processes, 
nodules or apertures.* The separation of Hydrosera is how- 
ever completed, I submit, by the presence of the very re- 
markable appendages I have described, and which afford a 
character so very distinct from what is to be seen in any 
other alluded genera. 


* Vide ‘Micrographic Dictionary,’ and Kiitzing, “Species Algar.” 


254 


REVIEWS. 


Clinical Lectures on the Principles and Practice of Medicine. 
By Joun Hucues Bennert, M.D., F.R.S.E. Edinburgh: 
Adami aiid Charles Black. 


A.tHovcH this is a second edition of a work well known, 
and its main purpose beyond the sphere of our criticism, we 
think it right to bring it before the notice of our readers, 
because it contains a large amount of matter bearing directly 
on microscopic research. Dr. Bennett is one of those teachers 
of medicine, who has, from an early period of his career, 
recognised the importance of conducting pathological re- 
searches by the aid of the microscope, “and in this work 
abundant evidence is afforded of the value and necessity of 
this instrument to the practitioner of medicine. In an early 
number of this Journal (volume I, page 223), we reviewed Dr. 
Bennett’s ‘ Introduction to Clinical Medicine, and recom- 
mended it to the notice of our medical readers, as conveying a 
just estimate of the value of the microscope in pathological re- 
search. In the present work the practieal application of this 
instrument to the various forms of disease in which it may be 
employed is fully brought out. In fact, with regard to a large 
number of the forms of disease no true theory of their 
nature can be formed independent of an investigation by the 
aid of the microscope. It is in the section devoted to the 
principles of medicine that Dr. Bennett handles the facts 
supplied by microscopic research in the most masterly 
manner. This section should be studied by all those who 
are anxious to understand the intimate causes engaged in the 
production of disease, and what are the changes which are 
necessary to the establishment of health. We should not 
pretend, even had we space here, to criticise Dr. Bennett’s 
theoretical or practical conclusions from the observations he 
records, but we draw attention to them, as showing the com- 
parative valuelessness of any observations or deductions on the 
intimate nature of organic disease without microscopic in- 
vestigation. 

We select two passages from this section of the work on 
exudation and degeneration, not on account of any novelty 
they present, but as illustrations of the manner in which the 
subject of pathology is treated. 


“Tubercular exudation has been spoken of as presenting a miliary infil- 


BENNETT'S CLINICAL LECTURES. 255 


trated or encysted form; but these distinctions have no reference to struc- 
ture, but merely to the extent and age of the exudation. It generally 
presents a yellowish or dirty-white colour, and varies in consistence from a 
substance resembling tough cheese to that of cream. Sometimes it is soft 
at one place, and indurated at another. On section, when tough, it pre- 
sents a smooth or waxy, and when soft, a slightly granular surface. On 
pressure if is friable, and may break down into a pulpy matter, but never 
yields a milky juice. 

* A small portion squeezed between glasses, and examined under the 
inicroscope, presents a number of irregular shaped bodies approaching a 
round, oval, or triangular form, varying in their longest diameters from the 
1-2000th to 1-1200th of an inch. These bodies contain from one to seven 
granules, are unaffected by water, but rendered very transparent by acetic 
acid. ‘They are what have been called tubercular corpuscles. Tiey are 
always mingled with a multitude of molecules and granules, which are more 
numerous as the tubercle is more soft. Occasionally, when softened tu- 
bercle resembles pus, constituting scrofulous purulent matter, we find the 
corpuscles more rounded, avd approaching the character of pus-cells. They 
do not always, however, on the addition of acetic acid, exhibit the peculiar 
granular nuclei of these bodies. 

“The gray granulations described by Bayle may be seen on careful ma- 
nagemnent of the light, after the addition of acetic acid, to contain similar 
bodies to those described as tubercle corpuscles, closely aggregated toge- 
ther, with their edges indistinct, and containing few granules. 

“Cretaceous and calcareous tubercles, on the other hand, contain very 
few of these bodies, their substance being principally made up of numerous 
irregular masses of phosphate of lime, and a greater or less number of 
erystals of cholestrine. 

“Tubercle corpuscles may be associated with pus and granular cells, as 
well as those peculiar to glandular organs or mucous surfaces in various 
stages of fatty transformation and disintegration. With all these they 
have frequently been confounded.” (pp. 1438, 144.) 

Futly Degeneration of Muscle.—“There can be no doubt that the fibro- 
albuminous substance constituting flesh is capable of undergoing a trans- 
formation into fat. Of the exact chemical nature of that transformation 
we have yet to be informed; but it may not only be observed in the dead 
body, but may be produced artificially, by exposing muscle to a running 
stream of water, whereby it is changed into adipocere. In voluntary muscle, 
we observe that the degeneration commences with diminished distinctness 
of the transverse strie, especially at the circumference of the fasciculus. 
As this extends inwards, minute molecules of fat occupy the position of the 
stri, and at length obliterate them; gradually these coalesce, globules of 
various sizes are formed within the sarcolemma, and the normal structure of 
voluntary muscle disappears. During the early changes the fasciculus be- 
comes soft, exhibits a tendency to crack crossways, and ultimately is so 
pulpy as to be capable of being squeezed easily into an amorphous mass, 
from which large oil-drops exude. To the naked eye, the muscular sub- 
stance becomes paler, and more and more fawn-coloured, and at length 
yel.ow, whilst its normal density is greatly diminished. These changes are 
easily observed in the heart, in which organ they have been made the sub- 
ject of special research by Ormerod, Paget, Quain, and others. The histo- 
logical and clinical researches of Dr. Quain on this subject are of the 
greatest importance. 

* Allthe voluntary muscles, however, are susceptible of undergoing a si ni- 
lar lesion, and it may be not unfrequently seen in those of the lower ex- 
tremity after long-continued paralysis, disease of the hip-joint, or other 


256 BEALE, ON URINE, ETC. 


lesions which necessitate immobility of the parts. In this case, and occa- 
sionally in the heart itself, in addition to the transformation of the muscular 
fasciculi above described, adipose tissue accumulates between them, and by 
compressing their substance adds to the rapidity and completeness of the 
transformation. In such cases the muscles are of a pale yellow colour, 
yielding on section large quantities of oil, while they preserve their usual 
form and fibrous look. J have seen all the muscles of the lower extremities 
so affected. Occasionally, while some muscles exhibit this transformation 
in its last stage, others close beside them present their normal red colour, 
so that the limb on dissection resembles the alternate red and fatty streaks 
of bacon. In this case the degenerated muscle has the whole of its fasci- 
culi transformed into adipose cells, with nuclei. 

“Tn involuntary muscles fatty degeneration may also be observed, al- 
though it is by no means so common as in voluntary ones. In this case, 
oily molecules are deposited in the elongated fusiform cells of which the 
texture is composed, which by their pressure on the nucleus cause its disap- 
pearance. Whether the distended pregnant uterus shrinks to its normal 
proportions after delivery wholly in consequence of such a degeneration 
(Heschl) is a point not yet determined in pathology. But there can be no 
doubt that many of the greatly enlarged fusiform cells of the organ, do be- 
come more or less crowded with fatty granules.” (pp. 226-228.) 

In his preface, Dr. Bennett states that he has “been long 
persuaded that mere description of morbid appearances, and 
especially of those that are made visible by means of the 
microscope, communicate only feeble or imperfect ideas to 
others.” He has accordingly abundantly illustrated his work 
with wood-engravings, of which there are nearly five hundred 
in the volume, mostly devoted to microscopic appearances. 
This work will, we are sure, greatly enhance the reputation 
of Dr. Bennett as a practical pathologist, and find its way to 
the study of every scientific practitioner of medicine. 


Illustrations of the Constituents of Urine, Urinary Deposits, and 
Calculi. By Lionet 8S. Beatz, M.B., F.R.S. London: 
Churchill. 


Tue object of Dr. Beale in preparing these illustrations 
has been to place in the hands of medical students and prac- 
titioners of medicine, at a moderate price, a series of correct 
representations of the various deposits found in healthy and 
morbid urine, as well as of salts held in solution, or formed 
by chemical re-agents in this secretion. The work contains 
thirty-seven plates, with upwards of one hundred and seventy 
figures and accompanying letter-press, and seems well 
adapted to secure the object Dr. Beale had in view in its 
publication. It embraces almost all possible forms of objects 
that could be presented to the student in connexion with the 
urine. It is also accompanied by a frontispiece and wood- 
cut, illustrating the anatomy of the kidney, 


PROCEEDINGS OF SOCIETIES. 


MicroscoricaL Society, April 21st, 1858. 
Dr. Lanxesrer, President, in the chair. 


General Alexander, Henry Carr, Esq., and Dr. G. Walker 
were balloted for, and duly elected members of the Society. 

The following papers were read : 

“On some Diatomaceze found in Noctiluca miliaris, with 
the best means of obtaining them,’ by Colonel H. H. C. 
Baddeley. 

“ Note on Campylodiscus Hodgsonii,” by Dr. G. A. Walker- 
Arnott. 

“ Account of Microscopical Observations and Collections 
made during a residence in India, and the voyage home,” by 
Dr. Wallich, illustrated by a large collection of drawings and 
objects. 


May 19th, 1858. 
Grorcr Jackson, Esq., in the chair. 


Dr. Wallich, W. T. Rickard, Esq., Rev. R. S. Bower, and 
Dr. F. Bossy were balloted for, and duly elected members of 
the Society. 

Mr. Roper read a paper “On the Genus Biddulphia and 
its Affinities.” 


June 16th, 1858. 
Dr. Lanxester, President, in the chair. 


Thomas Leonard, Esq., and John Smith, Esq., were bal- 
loted for, and duly elected members of the Society. 

H. W. Lobb, Esq., read a paper “ On the connecting link 
between the Animal and Vegetable Kingdoms.” 

Papers by W. Hislop, Esq., “ On anew Secondary Stage;’’ 
and by Captain Mortimer Slater, ‘‘ On certain new forms 
of Butterfiy Scales from India,” were read. 

The President made some remarks on the occurrence of 

VOL. Vi: U 


258 PROCEEDINGS OF SOCIETIES. 


Protococcus pluvialis in large numbers in a pond near 
Harleston, Norfolk, and exhibited specimens. 

A paper by Fitzmaurice Okeden, Esq., “On the Diato- 
mace of the South of Wales,” was read, illustrated by 214 
mounted specimens of Diatomaceze, which were presented to 
the Society. The special thanks of the Society were returned 
to Mr. Okeden for his valuable present. 

The meetings of the Society were then adjourned until 
October next. : 


Some difficulties having occurred in the practical applica- 
tion of Whitworth’s gauges recently recommended by the 
Society for the purpose of establishing an uniform screw for 
object-glasses, it was resolved, at the meeting of the Society on 
May 19, that ‘“'Two dozen steel taps be made for the use of 
makers of microscopes, wishing to adopt the universal attach- 
ment for object-glasses recommended by the Society.” 

If one of these taps be made to. enter the body of the 
microscope, it will receive any object-glass having a screw of 
the dimensions recommended, and the cylindrical gauges will 
not be required. 

The set of taps is in course of construction, and may in a 
few days be obtained of Mr. Williams, the Assistant-Se- 
cretary to the Astronomical Society, Somerset House, at the 
price of 5s. each. 


Dusiin Naturat History Socrety, May 7th, 1858. 
The President in the chair. 


The Rev. Eugene O’Meara read the following paper, “ On 
the occurrence of Anthozoids in Pleurosigma Spencerii.” 

“On Friday evening, April 30th, I was engaged in the 
examination of a gathering I had made two days previous 
from a running stream. On looking into the microscope I 
was much struck with the peculiar appearance of one of the 
forms that first presented itself in the field, a Plewrosigma 
Spencerii. The usual colour of the endochrome in this 
species is pale brown, but in the present instance it was a 
beautiful green. A number of granules of a bluish-green 
colour were distributed through the cell. In a few minutes 
I observed that the greater portion of the granules, at least 


PROCEEDINGS OF SOCIETIES. 259 


two thirds, moved with a sudden jerk to the lower part of 
the cell. Some of the granules passed out of the valve, and 
immediately after an anthozoid issued from the cell. Shortly 
after another made its appearance, and another, until six or 
eight had been extruded. All these organisms proceeded in 
the same manner from the valve, and exhibited themselves in 
the same spot, within, what appeared under a quarter-inch 
objective with No. 2 eye-piece, about one sixteenth of an inch 
from the extremity of the valve. In form the anthozoids, if 
at rest, would have presented very much the appearance of a 
spike of thistle-down. The head was of a pale-green colour, 
and round it the tail was lashed from side to side with great 
activity. On the same occasion several forms were observed 
presenting similar appearances, with anthozoids moving 
rapidly about in their immediate neighbourhood. Among 
these were two or three of the species named Cymatopleura 
Solea, but in no case, except the one just alluded to, did I 
observe them issuing from the valve. On the evening fol- 
lowing that in which the preceding observation was made, I 
examined a drop from the same gathering, when a great 
change was noticed to have taken place in the appearance of 
such Diatomaceous forms as occurred, compared with that 
which they presented the evening before. But few granules 
were seen. The endochrome also had changed its colour 
from green to olive, and instead of being diffused through the 
cell, was, in many instances, collected to a narrow band along 
each side of the cell, or at the opposite ends of it. In some 
cases these bands had broken up into isolated portions, and 
in others the valve was as free from endochrome as if it had 
been treated with acid.” 

The President dwelt on the necessity for repeating this 
observation, and suggested whether these were anthozoids 
or spermatozoids. In either case the observation was per- 
fectly new, aud would therefore most probably be disputed ; 
and therefore there was the greater necessity for repeating, 
and, if possible, confirming the observation, and the more 
glory should this discovery be confirmed.—Dudlin Paper. 


260 


ZOOPHYTOLOGY. 


Notes on two New Britisu Potyzoa. 
By Frep. D. Dyster, F.1.5. 


Sub-class. P. GyYMNOLAMATA. 
Order. CHEILOSTOMATA. 
1. Fam. Bicrttariap#&, Busk (‘ B. M. C.,’ Part I, p. 41). 
1. Gen. Huzleya, nov. gen., mihi. 

Polyzoary flexible, corneous or sub-calcareous. Cells biserial, pyriform, 
alternate. Aperture sinall, sub-terminal, unarmed. No avicularia or 
vibracula. 

1. Sp. #. fragilis, n. sp. Pl. XXI, figs. 1, 2. Sp. unica. 

Hab. Tenby, Dyster. 


The polyzoary, in this species, is from half an inch to one 
inch high, flexible, and white. The cells wider and rounded 
above, attenuated below; the upper portion of one being 
closely appressed to the slender lower part of the cell above. 
The dichotomous branches usually spring from the upper 
and back part of a cell, and occasionally, though rarely, 
from the middle or side. The aperture is small, rounded or 
semicircular above, and straight below. The margin is 
wholly unarmed, and not thickened. No vibracular or avi- 
cularian organs exist in any part. The ovicells have not 
been observed. The polypide i is ten-armed. 'The species was 
first noticed by me in a marine aquarium. 


2. Fam. Scrupariap®, Busk (‘ B. M. C.,’ Part I, p. 28). 
2. Gen. Brettia, nov. geu., mihi. 
Polyzoary erect, free, corneous, flexible. Branches given off behind and 
above the aperture of a cell. 
2. Sp. B. pellucida, n. sp. Pl. XXI, figs. 3—5. 
Hab. Tenby, Mrs. Brett ; Dyster. 


The polyzoary, about half an inch high, is perfectly trans- 
parent ; the cells are much elongated, fistular, with an oval 
aperture, rounded above, pointed below, and furnished with 
from five to nie marginal spines, irregularly placed. The 
polypide has ten arms; and the ovicells haye not been ob- 
served. This species was also first noticed in a marine aqua- 
rium by Mrs. Brett. 

It is singular that neither of the foregoing forms should 


ZOOPHYTOLOGY. 261 


have been detected in their natural habitat. The Huzleya 
grew in a tank of my own filled, of course, with water from 
the Bay, which had not been changed for many months. The 
other beautiful Polyzoan was found by my friend Mrs. Brett, 
in a tank devoted to Actinie, but of which the water was 
changed pretty frequently. 

I had long observed the presence of the Huxleya in my 
tank, but fully believing it to be Eucratea chelata, had never 
taken the trouble to examine it, and, unfortunately, when I 
did so, the polypides were dead, and nearly decomposed. 
They appear to communicate very freely with the general 
sarcode of the polyzoary, as much so as in Laomedea and 
other hydroid Polypes. The retractor muscles are very long. 
The nearest form to Huxleya would probably be Halophila, 
Gray (‘B. M. Cat.,’ p. 43, pl. xxx). 

In the case of Bretiia, its discoverer laid it aside after 
gathering it, and it was not examined till after death; but 
there is no reason to suppose that there is anything dis- 
tinctive about the polypide. 


On some MAavEIRAN Potyzoa. 
Collected by J. Yates Jonnson, Esq. 


(Continued from No. XXII, p. 129.) 


We here give figures and descriptions of some species of 
Madeiran Polyzoa, additional to those contained in a former 
part of the Journal. 


]. Fam. BriceLtiartap#, Busk. 
1. Gen. Bugula, Oken. 
1. B. ditrupe, n. sp., Busk. Pl. XX, figs. 7, S. 

Cells biserial, elongate, fusiform. Aperture wide, elongated, with two 
or three marginal spines on the outer and one on the inner side of the 
aperture above. Avicularia capitate, attached to the side of the cell below 
the middle. 

Hab. Madeira, Johnson. On the shell of Ditrupa acuminata. 


The present species is distinguished from B. flabellata by 
the biserial arrangement of the cells, and from B. dentata 
by their elongated and fusiform shape. Independently, how- 
ever, of these characters, the general habit and very peculiar 
site of growth of B. ditrupe, formeriy noticed, would alone 
suffice to indicate its specific independence. 


262 ZOOPHYTOLOGY. 


2. Fam. Mrmpraniponip&, Busk. 
2. Gen. Membranipora, Blainville. 
1. M. antiqua, n. sp., Busk. Pl. XX, figs. 1, 2. 

Area of cell pyriform, irregular, arched above, and either pointed or 
truncate below. Aperture sub-trifoliate, or somewhat contracted on the 
sides below the middle. Septa simple, not grooved. Numerous vibracular 
cells irregularly scattered throughout the polyzoary among the others, of an 
eusiform or falciform figure. 

Hab. Madeira, Johnson (on shell). 


A considerable number of fossil species of Membranipora, 
ard several of Hschara, are characterised by the presence in 
various points of the polyzoary of cells differmg in form and 
size from the common polypide-cells. From analogy with 
similar cells in several species of Lunulites, which are known 
to be vibracular organs, there is little or no doubt that the 
cells in question in the Membranipore and Eschare are of 
the same kind. And this supposition is further confirmed 
bythe circumstance, that in MW. stenostoma, Busk (‘ B. M. Cat.,’ 
p- 60, pl. c, fig. 1), avicularian cells are present, similarly 
disposed with relation to the polypide-cells. 

This peculiar character in the present species, by which it 
is distinguished from all other recent Membranipore with 
which I am acquainted, with the single exception above no- 
ticed, renders it a form of particular interest, when compared 
with many fossil species, occurring as it would seem in the 
Cretaceous formation. Instances of these will be found in 
the ‘Paléontologie Frangaise’ of M. D’Orbigny, and more 
especially in the forms described and figured as— 

Cellepora Xiphia, p\.dcexiii, figs. 3, 4. 
ee Xanthe, ib., figs. 5—7. 


A Michaudiana, pl. decxii, figs. 3, 4. 
= Xelimia, ib., figs. 15, 16. 
3 Parisiensis, ib., figs. 13, 14. 
Semieschara simplex, pl. decix, figs. 1—4. 
55 excavata, dccx, figs. 6—9. 


As well as in Hagenow’s ‘ Bryozoen der Maastrichter 
Kreidebildung,’ in the forms denominated— 
Cellepora Koninckiana, pl. xi, fig. 10, 


, depressa, ib., fig. 13, 
3 camerata, ib., fig. 9, 


and others. 


3. Gen. Lepralia, Johnston. 
1. L. sceletos,n. sp. Busk. Pl. XX, fig. 3. 


Outline of cell oval; anterior wall constituted of rib-like spines, six or 
seven on each side, which meet and interdigitate on the median line. An 


ZOOPHYTOLOGY. 263 


ascending spine at each lower angle of the aperture. Avicularia of a blunt, 
rounded, elliptical form, scattered over the polyzoary among the cells. 


Hab. Madeira, Johnson. 


A very peculiar and well-marked species, characterised not 
only by the skeleton-like appearance of the cells, some re- 
semblance to which may be occasionally observed in L. nitida, 
but more especially by the large blunt avicularia scattered 
wregularly among the cells, as in L. monoceros, Busk, and 
L. margaritifera, Quoy and Gaim (‘ B. M. Cat.,’ pl. ci), in 
which latter the avicularia, though far smaller, are of pretty 
nearly the same shape as those of L. sceletos. 


2. L. radiata, Moll. Pl. XX, figs. 4,5. (‘ Quart. Journ. Micros. 
Sc.,’ vol. vi, p. 128.) 


3. Fam. CELLEPORID2. 
4. Gen. Cellepora, Fab. 
l. C. Hassallii (var. a). Pl. XX, fig. 6. 


The only difference apparent between the present form, 
and that taken as the typical species in the ‘B. M. Cat.,’ 
p. 86, pl. cix, figs. 4, 5, 6, is the absence in it of the punctures 
in the ovicell. Whether this is alone sufficient to constitute 
a specific distmection, may be considered doubtful. For the 
present, I am inclined to regard the Madeiran form simply as 
a variety of the British. 


ZOOPHYTOLOGY. 


s 


DESCRIPTION OF PLATES. 


PLATE XX. ~ ‘ 
Fig. yO 
— 1—Membranipora antiqua, x 25 diam. 
oa : ry) ” Xx 50 d. 


3.—Lepralia sceletos, x 50 d. 
4— ,, radiata, x 50d. 
5.—An avicularium of LZ. radiata. 
6.—Cellepora Hassalii (var. a). 
—7.—Bugula ditrupe, nat. size. 
8.— ,, as x 50d. 


PLATE XXI. 


1, 2.—Aualeya fragilis. 
3—5.—Brettia pellucida. 


PND RX oO) JOURNAL, 


VOLUME VIL. 


A. 


Achnanthes brevipes and parvula, 92. 
Actinocyclus triradiatus, 23. 
Allman, Dr. G. J., ‘On Fresh-water 
Polyzoa,’ reviewed, 36. 
Alge, fecundation of, by Pringsheim, 
173. 
# Fresh-water, 
207. 
Alternation of generations and parthe- 
nogenesis, 79. 
Amphiprora, notes on the genus 198. 
e complexa, 201. 
is duplex and paludosa, 165. 
- Ralfsii, 91, 164, 198. 
Amphora, structure of the genus, 184, 
202. 
55 marina, 206. 
pS membranacea, 24. 
5 Proteus, 206. 
suleata, 24. 
Aquarium, Dr. P. Redfern on applying 
the microscope to the, 77, 156. 
» R. Warington on the, 67. 
Arachnoidiscus, history of the genus, 
159, 188. 
Ehrenbergii and Japo- 
nicus, 161. 
yy Indicus and Nicobari- 
cus, 162. 


F. Currey on, 


ornatus, 162, 195. 
Archer, ‘William, catalogue of Desmi- 
diacee, 73. 
Archives of Medicine, Review of, 114. 
Association, British, Proceedings of, 77. 
Aulacodiscus formosus, 160. 


B. 


Baur, A., on ossification of primordial] 
cartilage, 26. 


» 


Beale’s ‘ Constituents of Urine,’ 256. 
» ‘How to work with the Micro- 
scope,’ reviewed, 43. 
Bennett, Dr., ‘ Principles and Practice 
of Medicine,’ reviewed, 254. 
Berkeley’s ‘Introduction to Cryptoga- 
mic Botany,’ reviewed, 176. 
Biddulphia aurita, Baileyi, rhombus, 
and turgida, 19. 
Blood-corpuscles, J. B. Hennessy, on, 
81. 
Bowerbank, Dr. J. S., on the vitality of 
the Spongiade, 78. 
Brightwell, T., on Rhizosolenia, 93. 
op on Triceratium and 
Chetoceras, 153. 
British Association for the Advance- 
ment of Science, 77. 
Beale’s ‘Archives of Medicine,’ re- 
viewed, 43. 
C. 
Carpenter’s ‘ Zoology,’ reviewed, 117. 
Cartilage, primordial, on the ensiieanigy 
of, by A. Baur, 26. 
Caterpillars, on the crystals contained in 
the Malpighian vessels of, 33. 
Chetoceras Peruvianum, 155. 
Cobbold, Dr. T. S., on a naked-eyed 
Medusa, 1 
Cocconeis excentricus and orbicularis, 
165. 
»  Seutellum, y, 24. 
Cohn and Wichura, Professors, on Ste- 
phanosphera pluvialis, 131. 
Cornea, on the normal and morbid, 49. 
Coscinodiscus concinnus, jimbriatus, 
limbatus, and perforatus, 20. 
= excentricus, labyrinthus, 
and stellaris, 21. 
cs ovalis, 22. 


266 INDEX TO 


Cryptogamic Botany, Berkeley’s Intro- 
duction to, reviewed, 167. 
Crystalline lens, T. Nunneley on the, 
136. 
Crystals, H. OC. Sorby on the 
microscopical structure of, 190. 
Currey, F., on Stephanosphera pluvialis, 
13]. 
o on Fresh-water Alge, 207. 


DD: 


Deane, Henry, on the history of Arach- 
noidiscus, 188. 
Desmidiacee, Archer’s Catalogue of, 73. 
Diatomacee, from the Menai Straits, 
123. 
3 marine species of Northum- 
berland, 118. 
an new species of, by F.C. S. 
Roper, 17. 
ay with four valves, 201. 
Ap with lamellar zones, 201. 
Donkin, Dr. A.S., on the marine Diato- 
macez of Northumberland, 118. 
Drilling holes in glass slides, 121. 
Dublin University Zoological and Bota- 
nical Association, Proceedings of, 73. 


E. 


Ellis, G. Viner, on involuntary muscular 
fibre, 63. 
Entopyla australis, 195. 
Epithemia marina and Radula, 165. 
Eunotia, notes on the genus, 202. 
Eupleuria incurvata and ocellata, 195. 
0 species of, 89, 163. 
Eupodiscus formosus, 160. 
i radiatus and tesselatus, 19. 


F. 


Facets, hexagonal, on finding the number 
of, in a given circle, by H. M., 83. 
Farrants, R. J., on a medium for 
mounting objects, 118. 

Fecundation of Alge, by Pringsheim, 
Wey. 

Frustrella hispida, Dr. Redfern on, 79, 
96. 


G. 


Gegenbaur, on marginal bodies of the 
Meduse, 103. 

Generations, alternations of, Dr. Lan- 
kester on, 79. 

Geological Society, Proceedings of, 190. 

Gephyria incurvata, &c., 91, 164, 


JOURNAL. 


H. 


Harting, Prof., on the refractive ndex 
of fluids, 107. 

Hemiptychus ornatus, 160, 195. 

Hennessy, J. B., on blood-corpuscles, 
81. 

Herapath, Dr., on the detection of 
strychnia, 62. 

Hexagonal facets in a circle, 83. 

Higgins, Rev. H. H., on the cultivation 
of mosses, 64. 

Himantidium, notes on the genus, 202. 

His, Dr., on the cornea, 49. 

Hislop, W., on object-finders, 192. 

Hogg on the Microscope,reviewed, 117. 


I. 


Inflammation of cornea, Dr. W. His on, 
54. 
Involuntary muscular fibre, G. V. Ellis 
on, 63. 
” ” Jos. Lister 


on, 5. 


nN 


Ue 


Jackson, Mr., on object-finders, 192. 

Johnson, J. V., on the zoophyto- 
logical fauna of Madeira, 124. 

Jones, Joseph, on physical influences 
exerted. by living membranes upon 
chemical substances, 189. 


K. 


K6lliker on muscular fibre, 31. 
» on the luminous organs of 
Lampyris, 166. 


L. 


Lacteal fluid, on the flow of, by Jos. 
Lister, 81. 

Lampyris, Kolliker on the luminous 
organs of, 166. 

Lankester, Dr. E., on the alternation of 
generations and parthenogenesis in 
plants and animals, 79. 

Linnean Society, Proceedings of, 64. 

Lister, Joseph, on involuntary muscular 
fibre, 5. 

5, on the flow of the lacteal fluid 
in the mesentery of the mouse, 81. 

Lithographs, Lionel Beale on obtaining, 
115. 

Lyons, Prof., on micrometric measure- 
ments, 81. 


M. 


Malpighian vessels of caterpillars, crys- 
tals in, 33. 


INDEX TO 


Maltwood, T., on a new object-finder, 
192. 

Medicine Archives, by Lionel Beale, 
MGS 

Medium for mounting objects, R. T. 
Farrants on a, 118. 

ie Dr. Cobbold on a naked-eyed, 


ae Gegenbaur on, 103. 
Membranes, - organic and inorganic, 
their physical influences on chemical 
substances, 189. 
Micrometric measurement, Prof. Lyons 
on, 81. 
Microscope, Jabez Hogg on, 117. 
i fifty-pound prize for obser- 
vations with the, 59. 
how to work with the, by 
Lionel S. Beale, 43. 
Microscopes, compound, on the applica- 
tion of, to aquaria, 77. 
Microscopical Society, Proceedings of, 
118, 192, 257. 
Miliolitide, W. 
Indian, 193. 
Mosses, Rey. H. H. Higgins on the 
cultivation of, 64. 
Mounting flies, 122. 
+ objects, 118. 
Muscular fibre, Kolliker on, 31. 


K. Parker on East 


N. 


Naked-eyed Medusa, Dr. Cobbold on a, 
ule 
Navicula, notes on the genus, 200. 
a dilatata, 25. 
Fr Libellus, 201. 
a Liber (3, 25. 
% palpebralis, 23. 
* Scalpellum and Scalprum, 
198. 
Nitzschia Radula, 23, 165. 
> virgata, 23. 
Nowell, B. J., list of Diatomacee from 
the Menai Straits, 123. 
Nunneley, T., on the crystalline lens, 
136. 
on the retina, 217. 
Nympheeacez, Dr. Ogilvie on the stel- 
late bodies of the, 59. 


O. 


Object-finders, on new, 192. 

Ogilvie, Dr. G., on the stellate bodies 
of the Nymphzacee, 59. 

Ossification of primordial cartilage, by 
A. Baur, 26. 


JOURNAL. 267 


Lets 


Parker, W. K., on East Indian Milio- 
litide, 193. 

Parthenogenesis, Dr. Lankester on, 79. 

Pleurosigma, notes on the genus, 196, 
200. 


» . @estuarii and angulatum, 
197: 

os angustum, 164. 

oF arcuatum, 165. 

3 Balticum 8, 197. 

5 carinatum, 164. 

5 compactum, 91. 


ae elongatum, 197. 
> lanceolatum, 165, 197. 


PP minutum, 164. 

Pe guadratum, 197. 

ee rectum, 164, 197. 

sy transversale 3, 25, 197. 


PA Wansbeckii, 197. 
Polyzoa, Review of Dr. Allman on 
Fresh- water, 36. 
Pringsheim on the 
Alge, 173. 

Prize of £50 for observations with the 
microscope, 59. 

Publication of private correspondence, 
196. 


fecundation of 


R. 


Ralfs, J., on the siliceous cell of 
Diatomacez, 14. 
Ralph, T. S., on illuminating objects, 
118. 
Ae on mounting objects, 
118. 
Redfern’s, Dr. P., method of applying 
the microscope to aquaria, 77, 156. 
* on Frustrella his- 
pida, 79, 196. 
Retina, structure of, 217. 
» rods of, 238. 
Refractive index of fluids, Professor 
Harting on, 107. 
Rhabdonema, species of, 91. 
+p structure of, by T. West, 
186. 
Rhizosolenia, T. Brigltwell on, 93. 
Roper, F. C. S., on new species of 
Diatomacee, 17. 
Royal Society, Proceedings of, 62. 
Royal Institution, Proceedings of, 67. 


S. 


Schlossberger on crystals in Malpighian 
vessels of caterpillars, 33. ; 


268 INDEX TO 


Siliceous cell of Diatomacee, by J. 
Ralfs, 14. 

Sorby, H. C., on the microscopic 
structure of crystals, 190. 

Spongiade, Mr. Bowerbank on the 
vitality of the, 78. 

Stellate bodies of Nympheacez, by Dr. 
G. Ogilvie, 59. 

Stephanosphera pluvialis, 
on, 131. 

Strie of Diatoms; relation between 
their direction and the arrangement 
of their dots, 200. 

. vary in appearance according 
to the mode of preparation, 163. 

Strychnia, Dr. Herapath on the detec- 
tion of, 62. 

Surirella australis, 195. 

Synonyms, reference to unpublished, 
196. 


F. Currey 


ite 


Thaumantias achroa, 1. 
Toxonidea, notes on the genus, 199. 
, Gregoriana and insignis, 
165, 197. 
Triceratium, filamentous 


species of, 
1595. 


JOURNAL. 


U. 


Urine, illustrations of constituents of, 
by Dr. Beale, 256. 


V. 
Vessels, minute, in web of frog’s foot, 
structure of, 8. j 
W. 


Walker-Arnott, Dr. G. A., on Am- 
phora, 184. 
7 on Arachnoidiscus, 159. 
7 on Arachnoidiscus, Pleu- 
rosigma, Amphiprora, Eunotia, and 
Amphora, 195. 


0 on Rhabdonema and Eu- - 
pleuria, 87. 
Warington, R., on the aquarium, 


67. 

Wenham, F.H.,on drilling glass slides, 
and mounting portions of flies, 121 
West, Tuffen, on the structure of 

Rhabdonema, 186. 


Z. 


Zoophytological fauna of Madeira, by 
J. Yates Johnson, 124. 

Zoology, by W. B. Carpenter, 117. 

Zoophytology, 124, 260. 


PRINTED BY J. BE. ADLARD, BARTHOLOMEW CLOSE. 


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ZOOPHYTOLOGY. 


DESCRIPTION OF PLATES. 


PLATE XVIII. 

Fig. 
1.—Lepralia distoma, X 25 d. 

Tas 50:d" 
2.—Membranipora trichophora, X 25 d. 

2a. x 50d. 
3.—L. vulgaris, X 25 d. 

3a. xX 50d. 

3 6.—Ovicell, x 25 d. 
4..—Membranipora tuberculata, x 50 da, 
5.—-Ldmonea Atlantica, x 25 d. 


PLATE XIX. 


1.—B. gracilis, x 50d. 
2.—Nellia Johnsont, n. sp. 


2a. x 50d. 
3.—Cryptolaria exserta, n. sp. 
oS a. - xt Sued: 


35. . © 50d. 


JOURNAL OF MICROSCOPICAL SCIENCE. 


DESCRIPTION. OF PLATE III, 


Illustrating Mr. Roper’s paper on some New British 


Diatomacecz. 
Fig. 
1.—Lupodiscus tesselatus. 
db. Ditto, structure highly magnified, 
2.—Coscinodiscus labyrinthus. 
b. Ditto, structure highly magnified. 


3.—C. (?) stellaris. 
4.—C. (?) ovalis. 
5.—<Actiuocyclus triradiatus. 
b. Ditto, structure highly magnified. 
6.—WNitzchia virgataab. 
a. Side view. 
b. Front view. 
7.--Amphora sulcata, 
8.—d, membranaced. 
6. Ditto, — represents self-division. 
9.—Cocconeis seutellum, var. y. 
10.—Navicula liber, var. B. 
11.—Pleurosigma transversale, var. p. 
12.—Coscinodiscus concinnus. 
a. Ditto, structure highly magnified. 


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JOURNAL OF MICROSCOPICAL SCIENCE. 


DESCRIPTION OF PLATE I, 


Illustrating Dr. Cobbold’s paper on Thaumantias achroa. 
Fig. 
1.—Thaumantias achroa, natural size. 
2.—Part of the convex surface of the umbrella, magnified 250 diameters. 
3.—Free extremity of a tentacle, magnified 40 diameters. 
4.—Portion of the same, magnified 250 diameters. 
5.—Proboscidiform peduncle, magnified 40 diameters. 
6.—Reproductive gland, magnified 40 diameters. 
7.—Radiating vessels and peduncle, viewed from above; showing more 
particularly the direction of the circulation and the form of the 
digestive cavity. The central vascular space is out of focus. Mag- 
nified 80 diameters. 
8.—Margin of the disc, with an ocellus between two tentacular bulbs, 
magnified 60 diameters. 
9 —Tentacular bulb and marginal vessel, magnified 250 diameters. 
10.—Ocellus and marginal vessel, magnified 250 diameters. 
11.—Central vascular space, magnified 250 diameters. The last three 
figures exhibit the circulating corpuscles. 
12.—Marginal portion of a reproductive gland, showing the ova and paren- 
chymatous cellules, magnified 250 **~ters, 


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JOURNAL OF MICROSCOPICAL SCIENCE. 


DESCRIPTION OF PLATE IV, 


Illustrating Dr. Redfern’s paper on Flustrella hispida. 


Fig. 

1.—Ceenecium of Flustrella hispida removed by horizontal section from 
the frond of Chondrus mamillosus. 

2.—Ditto, ditto, showing cells with fewer hairs on their sides and a more 
imbricated arrangement. 

3.—A single cell of the same separated from those which surrounded it. 
Figs. 1, 2, and 3 magnified. 

3 dis.— Cencecium of a specimen gathered on the coast of North Wales. 

4.—Polypide removed from its cell, showing its digestive viscera. 

5.—Portion of a tentacle, showing the natural state of its investing ciliated 
epithelium. 

6.—Ditto, denuded of its epithelium. 

7.—Ditto, showing its epithelial cells distended by fresh water. Figs. 
5, 6, and 7 magnified. 

8 to 10.—Unciliated ova or statoblasts densely filled with cells. 

9.—Ditto, from which some of the cells have escaped, showing the remain- 
ing contents more distinctly cellular. Figs. 4, 8,9, and 10 magnified. 

11.—A single polypide in its cell, with a gemma forming on its wall. 

12.—The same after two days, showing a striation produced by rows of 
highly refractive corpuscles. 

13.—Ditto, on the third day, showing the polypide like a bud at the bottom 
of the new cell. 

14.—Ditto, on the fourth day, showing traces of the formation of three 
other gemmee. , 

15.—Ditto, on the seventh day. The polypide has assumed the form of a 
bent tube; the cell has four well-marked hairs formed on it; one 
only of the other gemme is now distinctly seen. 

16.—Ditto, on the twelfth day. The projecting part of the cell has become 
flexible and greatly more prominent; the wall of the perigastric 
space and the tentacles are quite distinctly seen; no other gemma 
is distinctly visible. 

17 and 18.—Ditto, on the thirteenth day, showing states of retraction and 
protrusion. The movements are now remarkably distinct, the ten- 
tacles much longer, the perigastric space clearer, the rows of refrac- 
tive globules greatly diminished in number and size. 

19 and 20.—Ditto, on the seventeenth day, showing the whole digestive 
system beautiful ly distinct, as well in the state of retraction as of 
protrusion; a gemma appears to be forming on the side of the 
‘newly developed cell. 


JOURNAL OF MICROSCOPICAL SCIENCE. 


DESCRIPTION OF PLATE V, 


Tilustrating Mr. Brightwell’s paper on Rhizosolenia. 


‘ig. 

Te aniensdlonis ornithoglossa, copied from Ehrenberg. 

2.— Fe Calyptra, ditto. 

3.— A Americana, ditto. 

4.— hebetata, Bailey. Original figure. 

5.— 1 styliformis, n. sp. A very small entire frustule. 
Aes i calyptriform valve, detached, seen on the 

ventral aspect. 

Dieah53 4 calyptriform valve, dorsal aspect, and proximal 


portion of a frustule, breaking up. 
calyptriform valve, lateral aspect, aud portion 
of a frustule attached. 
ible A portion of one of the slenderest frustules, 
lengthening ‘of intermediate portion, and 
formation of new “ annuli.” 
portion of the broadest frustule yet found, 
-0053 in diameter. 
6.—Rhizosolenia imbricata, n. sp., in self-division. 
7.—a. 5; setigera, u. sp., self-division just commenced. 

Be lis » the same state, further advanced; the trans- 
parent portion above the dotted line was seen by Col. Bad- 
deley (to whom we are indebted for the drawings from 
which figs. 7 a, 7 6, 7 c, were taken) to become detached and 
thrown off. 

c. R. seligera, showing the very faint markings on the intervalvular 
portion of the frustule. 

9.---Rhizosolenia alata, nu. sp., from a sketch by Mr. G. Norman, of Hull. 
a. . portion of another frustule, original sketch. 


C. >) 23 


é. 39 29 


The figures all magnified 400 diameters, except those taken from Khrenberg. 


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JOURNAL OF MICROSCOPICAL SCIENCE. 


DESCRIPTION OF PLATE VI, 
Illustrating Mr. Currey’s paper on Stephanosphera pluvialis. 
Fig. 
1.—A full-grown Stephanosphera in which the germ-cells have become 
spindle-shaped with protoplasmic elongations. 
2.—Full-grown resting-cells. 
3.—The beginning of division in a resting-cell. 
4,—A resting-cell in which division has advanced further. The outer 
membrane is no longer perceptible. 
5, 6, 7, 8, 9.—Subsequent successive stages of division, showing (in 9) 
the formation of cilia. 
10, 11, 12.—Naked zoospores. 
13, 14.—Encysted zoospores. 
15.—An encysted zoospore with protoplasmic elongations of the primor- 
dial cell. 
16, 17.—Division of encysted zoospores. 
18, 19.—More advanced stages of the same. 
20,—A young eight-celled Stephanosphera family. 
21.—A family of only four cells. 
22, 23.—Young Stephanosphere with the cellular envelope still visible 
within the membrane of the mother-cell. 
24.—Young Stephanosphera with the cellular envelope somewhat flattened. 
25.—Young Stephanosphera viewed equatorially. The outer membrane is 
constricted between the primordial cells, and the latter exhibits 
chlorophyll-granules. 
26.—Formation of microgonidia from the primordial cells of a young 
Stephanosphera family. 
27.—Free microgonidia. 


All the figures x 500. 


JOURNAL OF MICROSCOPICAL SCIENCE. 


DESCRIPTION OF PLATE VII, 


Tllustrating Mr. Nunneley’s paper on the Crystalline Lens. 


Fig. 
ee Lens of infant. 64. Of young adult. c. Of old person. 
2.—Enlarged lens, to show the different curves of its two surfaces and the 
arrangement of its layers of fibres. 

' 3.—a. Two fibres from the middle part (midway from margin and axis) of 
lens of haddock. 4. Of cod, after being in boiling water and 
well dried, when the fibres are very clear and transparent. 

' 4.—a. Three fibres from middle part of lens of frog. Two are shown 
completely twisted over, by which their flat riband-like form is 
well seen. 4. A group of fibres seen on the edge. 

5.—From turtle. a. Two fibres from near the surface of lens. 6. A 
fibre from the same layer in ether, to show the serrations more 
developed by this agent. c. Four fibres from near the axis, where 
many are almost cylindrical, and marked with longitudinal lines as 
though made up of smaller filaments. 

6.—From lens of a cock. a. Cells filled with granules from quite the 
outer surface of lens close to the capsule. 6. Other of these cells 
elongated, as though changing into fibres. c. Fibres from outer 
layers of lens. d. Fibres from tear the axis of lens, nearly 
cylindrical, but some, as on right, are larger and flat, and at e a 

broad one is shown curved over. 

7.—Fibres from the lens of rat, squirrel, and hare. a@. From middle. 4. 
From near axis of lens of rat. c. From near outer part of lens of 
squirrel. d. Four fibres from middle of lens of hare after coagu- 
lation and being dried, two are seen flat, and two on edges. 

8.—From lens of ox. a. Fibres from near surface. 8. From near middle. 
c. From near axis of lens. d. Bundle of fibres broken transversely 
from near middle of lens. e. Bundle of fibres seen edgeways. 

9.—From cat. a. Two fibres from outer layer showing how very irregular 
in outline they become from the effect of water at 212°F. &. 
Fibres from near the middle of lens (midway between axis and 
margin) of other eye of same animal. 

10.—From human lens. a. Fibre from outer layer seen on the flat surface. 
6. Another fibre from same layer curved over. c. Fibre seen on 
its edge. d. Fibres from near the middle of Jens. 

11.—Epithelial cells from inner surface of capsule of lens. a. From anterior 
capsule. 0%. From posterior, where I have found them arranged 
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ance. From sheep. 

12.—Cells from inner surface of anterior wall of Petit’s canal or suspensory 
ligament, in some animals they are more or less oval, and contain 
a nucleus with nucleoli, from sheep. All these cells are rendered 
more distinct by acetic acid. 

13.—Cells from inner surface of capsule of lens of duck. 


The figures are magnified 450 diameters. 


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JOURNAL OF MICROSCOPICAL SCIENCE. 


DESCRIPTION OF PLATE VIII, 


Illustrating Mr. Brightwell’s paper on Triceratium and 
Cheetoceros. 


Fig. 
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2.—The same, front view. ‘The frustules are united often in a filament of 
six to eight frustules. 
3.—Tr. undulatum in the doubtful state, with endochrome. 
4.—The same without the endochrome, showing the banded and fringed 
frustules. 
5.—The same, a four-sided end. 
6.—Tr. malleus, end view. 
7.—The same, in filament. 
8.—Var. of Zr. undulatum, Monterey earth. 
9.—Chetoceros Peruvianum. 
10.—The same. 


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JOURNAL OF MICROSCOPICAL SCIENCE. 


DESCRIPTION OF PLATES X, XI, 


Illustrating Mr. Nunneley’s paper on the Structure of the 
Retina. 


PLATE X. 
Fig. : 
1.—Vertical section of human retina, to show the relative position of its ele- 
ments—(plau of). 1, choroid coat ; 2, rods ; 8, outer layer of granular 
cells; 4, indiseinct fibrous layer; 5, inner layer of granular cells, 
in which are imbedded larger vesicular cells, and towards the inner 
surface is found, 6, the vascular layer, which consists of delicate 
vessels derived from the larger branches of the central artery of 
retina, which run on the inner surface of 7, which is the layer 
formed by the fibres of the optic nerve; 8, transparent cells 
attaching the retina to the hyaloid membrane. 
9.—Human rods, x 4:50 linear. 
3.—Rods in various stages of alteration. a@. By the addition of water, or 
after the eye has been in dilute spirit, or a short time after death. 
6. After being treated with dilute chromie acid. ec. After twenty- 
four hours’ immersion in Goadby’s solution. x 450. 
4.—Inmer surface of posterior portion of human retina, to show the 
granular layer with larger circular cells amoagst which the nerve- 
fibres run; to thé left is seen an artery dividing into two branches. 
x 450. ‘ 
5.—Same surface with 1-12 object-glass, and achromatic condenser, x 600, 
without nerve-fibres, to show the clear transparent cells (probably 
enlarged by endosmose), and the cellular character of the so-called 
granular layer, which consists of true cells containing very refractive 
nuclei. 
6.—Nerve- fibres from posterior part of human retina; they appear to 
bifureate and to join each other again. x 450. 
7.—Ilvregular fiat cells found in the eyes of most, if not ail, animals. 
a. Krom human feetus. 6. From pig. ¢. From sheep. d. From 
bullock. Alijust dead. x 450. Are they caudate gangliform cells ? 
8.—Turkey. @. Conoidal rods surmounted by coloured globules. 6. 
Coloured globules of various sizes detached. ¢. Cylindrical rods. 
d. Qvoid bodies with coloured globules. x 450. ¥ 
9.—Retina of birds. @. Conoidal rod with coloured globule from canary 
bird. 6. Conoidal rods with ecloured globules from various breeds of 
domestic fowls; in the same bird the size and exact shape varies, 
perhaps, at least to some extent, depending upon varying pressure 
against each other. ¢. Cylindrical rods not surmounted by coloured 
globules. d. Ovoid bodies (bulbs, cones) with coloured globules. 
e. Coloured globules seen on outer surface of retina as though with 
anucleus, which they do not possess. / Coloured globules seen in 


PLATE X (continued). 


Fig. 
profile, showing a small spur, by which possibly they adhere to the 
conoidal rods, though in the great majority this spur cannot be 
seen; they appear to be true globules. g. Conoidal rods and ovoid 
bodies become granular. 

10.—From duck. a@. Cylindrical rods, which are larger and more numerous 
than in the fowl; in one duck all the rods were cylindrical, aud many 
of them were surmounted by the ruby- and canary-coloured globules : 
there were none conoidal, except such as shewnate. 46. Conoidal 
rods from another duck. ¢. Ovoid bodies without coloured globules. 
d. Ovoid bodies with coloured globules. e. Ovoid bodies with a 
conoidal leg attached at the zzzer side ; this process becomes detached 
and breaks up into dises, as do the cylinders, while the more globular 
portion becomes granular; so that it is difficult to say whether 
these are ovoid bodies with a portion of rod and globule accidentally 
attached, or whether the ovoid bodies are not really altered conical 
rods deprived of the inner process. jf. Cylindrical rods and ovoid 
body with coloured globules accidentally attached. x 450. 

1].—From swan and goose. a. Conoidal rods with coloured globules. 4. 
Ovoid bodies with similar globules. c. Three of the rods altered. 
d. Coloured globules fusiform in shape. e. Strong cylindrical nerve- 
fibres in retina from swan, jf. Cylindrical and conoidal rods. gy. Ovoid 
bodies. %. Rods curled round so as closely to resemble ovoid bodies. 
2. Rod curled into hook at one extremity. x 450. 

12.—From Guinea fowl. a. Outer surface of retina with rods and globules 
in situ. 6. Coloured globules detached. x 450. 

13.—From green turtle. a. Long and short cylindrical rods, neither of 
which are very numerous. &. Conoidal rods, for the most part sur- 
mounted by a coloured globule. c. Ovoid bodies surmounted by 
coloured globules. d. Very nearly similar bodies without coloured 
globules. e. Ovoid bodies with a short cylindrical leg attached at 
inner side, intwo of them it is seen breaking off; they are surmounted 
by coloured globules. f These different bodies after the lapse of 
a few hours; immediately on the addition of water; and also from 
another turtle, which, before being killed, was in a very languid and 
feeble condition. g. Average size of ruby globules. 4%. Of canary 
globules. ¢. Three of these globules in profile to show spur which 
some appear to possess, but by far the greater number seem to be 
true globes; when not exactly in focus, as the globules of birds, 
they appear to have a nucleus, which, however, they have not. 7. 
Nerve- fibres forming a layer in retina. 4. Finely granular cells. 
x 450. 

14.—Turtle; form, size, and position of elements of outer coat of retina, 
showing the cylindrical and conoidal rods with the coloured globules, 
and at their base the ovoid bodies. x 450. 

15.—Section of retina of turtle. a. Rods. 8. Coloured globules. c. Ovoid 
bodies. d. Granular cells. e¢. Nerve-fibres and blood-vessels. (7. 
Transparent cells between last and the hyaloid surface. x 450, 


PLATE XI. 


Fig. 

1 —Portion of back part of retina of bullock seen from the inner surface, 
to show nerve-fibres and layer of granular cells, which have been 
partially removed the better to show the fibres forming a layer, with 
1-12. x 600. 

2.—Fibrous layer of retina, showing varicose enlargements in the nerve- 
fibres, and also double-walled cerebral cells. x 450. From back 
part of retina of rabbit. L haye seen the same structures in the ox 
and the sheep, but not quite so distinctly. 

3.—Varicose fibres and clear oii-like cerebral cells from optic nerve in the 
pig, at its entrance into the eyeball. 

4,—ILayer of cells attaching retina to hyaloid membrane ; at first they are 
perfectly transparent, but soon become very finely granular. They 
are found in most animals, and are very distinct in the rabbit. 

5.—From turtle. ‘There are a few large flat cells with large irregular 
granular nuclei. x 450. Are they the caudate gangliform cells ? 

6.—From birds. a. Conoidal rods after some hours’ immersion in dilute 
spirit, showing, towards the czwer end, a conical process with a 
transverse mark as though breaking off here. &. Nerve-fibres from 
anterior part of retina of Cochin cock; after being forty-eight 
hours in dilute spirit, they formed a complete layer imbedded in the 
granular ceils; many of the fibres could be traced for a considerable 
distance, others were much shorter as though terminating at various 
points, all were more or less varicose ; the dilations showing double 
walls, and with them were some double-walled cells. c. Delicate 
cells, which are during life, or immediately after death become, 
minutely granular; they are very abundant in all birds. d. Perfectly 
transparent cells, which soon become very large and irregular in size 
and shape, probably from pressure and overlapping each other; they 
appear to form a layer between the retina and hyaloid; these are 
from the canary bird; they are not larger in the goose or turkey 
than in this little bird. x 450. 

7.—Capillary vessels of human retina; the artery from which they are 
given off measured 1-100 of an inch in diameter; the capillaries 
not more than 1-4000; washed with dilute liquor potasse, which, by 
erie the nerve-structures, renders the congested vessels very 

istinct. 

8,—Terminal vessels in human retina. They form a series of loops a little 
distance from the ora serrata. a. Ciliary processes. 0. Loops of 
capillaries joining to form trunk, e. 

9.—From frog. a. Very large cylindrical rods ; most, however, are of size 
seen at 6. Some of these are rather broader at their inner extremity 
than at the outer; many, but not all, are surmounted with a light- 
brown coloured globule, like those of birds and the turtle, but with 
much less colour; these are shown detached at c. They should not 
be shown with nuclei. d. Rods changed by the addition of water ; 
they curl up, become granular, and look like coffee-berries. e. Rods 
after addition of salt and water, which induces much less change than 
water. jf. In one frog I found three rods with conical inner ends, 
and transverse marks as here shown. g. A few large cells with 


pigment-granules, not much unlike some found in the brain, are seen. 
«K 450. ; 


PLATE XI (continued). 


Fig. 

trom toad. a. Three rods; the majority are not so long as the 
longest. &. Size of pale yellowish globules attached to some of the 
rods. xX 450. 

11.—From alligator. a. Rods. 4. Fibrous layer of retina when fresh. 
c. Same layer with granular cells after six hours’ immersion in dilute 
spirit; the nerves have become varicose. xX 450. . 

12.—From chameleon. a. Rods. 4, Granular cells, with which are some 
larger-brain cells. ce. Nerve-fibres of retina. x 450. 

13.—From golden carp, Cyprinus auratus. a. Cylindrical rods. 6. Conoidal 
bodies, cones jumeaux, at first perfectly transparent. c. These same 
bodies, after a short time, or immediately on the addition of water, 
the lower bulbous portion swells, becomes granular, irregular, splits 
in the middle, forming the coffee-berry body, breaks up, and 
disappears, while the surmounting conical leg breaks off, splits into 
dises, as do the cylindrical rods, and disappears. d. Ovoid ceils of 
various sizes, of a dark fuscous colour; they resemble brain-cells. 
e. Nerve-fibres of retina. x 450. 

14.—From sand-dab, Platessa limanda. In this fish the cones are not 
numerous, the rods and granular cells are far more so. a. Rods. 
b. Conoidal bodies. x 450. 

15.—From litile weaver, Trichinus vipera. In this fish the cones are very 
distinct, and far more numerous than in the last, but very few have 
the clear conical leg, and for the most part they lie singly and not 
in pairs as is common in fish. The rods are neither numerous nor 
well developed. «@. Rods. 4. Cones, which in this and the last fish, 
if not in life granular, become so before they can be examined. x 450. 

16.—From whiting, Merlangus vulgaris, which is a good fish for examination, 
the cones being well developed, a. Small rods. 4. Cones with 
single bulbs and double conical legs, at first perfectly transparent 
and homogeneous, but in a very short time immersion in dilute spirit, 
or instantly on the addition of water, the changes shown at ¢ occur, 
and they disappear in granules. x 450. 

17.—From eel. a. Rods, which are numerous. &. Cones, which are not so 
numerous. c¢. Brownish red transparent cells, in character not unlike 
the coloured globules of birds, except that they contain a nucleus. 
They are not more than half the size of the blood-globules, and they 
are circular; on the other hand, they are much too large for the pig- 
ment-cells of the choroid, which in colour they resemble. d. Com- 
mencing change in rods or cones, which now (with 1-8) resemble, in 
size and form, au oatcorn. xX 450. 

18.—From cod, Gadus morrhua, where the retina is very thick and its ele- 
ments simple. @. Normal form and size of cone, the bulb is perfectly 
transparent and homogeneous; the conical process is single and has two 
transverse strix, where it soon breaks. 6. Cones altered a few hours 
after death. ¢. A cone seen to alter while under examination, a large 
granular vesicle formed in the middle, and at each end was a long fibre ; 
these subsequently swelled out, became granular, and disappeared. 
d. Inner surface of retina, some hours after death, showing the large 
flat nerve-flbres become greatly varicose; they are imbedded in a 
layer of granular cells, with which are also found many large traus- 
parent cells. x 450. 


rat =. 


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WWest Lips 


JOURNAL OF MICROSCOPICAL SCIENCE. 


DESCRIPTION OF PLATES XII, XIII, 


Illustrating Dr. Wallich’s paper on Triceratium and 
Hydrosera. 


PLATE XII. 
Fig. 
1.—Front view of 7riceratium serratum. 
2.—Valve of ditto. 
3.—More highly magnified view of one of the connecting plates during 
division, showing serrated edge and arcuate band. 
4.—T.. jimbriatum, front view. 
5.—Valve of ditto. 
6.—Fragment of valve exhibiting cellular structure. 
7.—Profile of a fragment, showing depth of cells. 
8.—Profile of fimbriz. 
9.—Three of the fimbrize, seen under a power of 600 diameters. 

10.—7. pentacrinus, front view. 

11.—Valve of ditto. 

12.—Connecting membrane of ditto. 

13.—Portion of ditto. 

14.—7", pentacrinus, four-sided variety. 

15.—T. annulatum. 

16, 17.—Two newly separated frustules, showing the supersistent counect- 
ing band, formed of the siliceous plates of their halves of the parent 
frustule ; the other or second layer having receded from these, and 
remained attached to the other newly liberated frustules. 


PLATE XIII. 


1.—Portion of Hydrosera triquetra in natural state. 
2.—Frustule of ditto, seen from above, as laid on one of its sides, the 
central angular ridge only being in focus. 
3.—Connecting membrane of same, showing one of the plates forming the 
annulus, with its imperfect septa. The other plate behind it out of 
focus. 
4.—End view of valve of same, showing cellulation under a power of 
950 diameters, the spines at the angles, and processes on one 
side. 
5.—Broken valve, showing one of septa. 
6 —Portion of same valve under power of 350 diameters, showing reticu- 
lated structure. 
7.—Portion of filament of H. compressa in natural state. 
8.—Frustules of same undergoing division, and exhibiting the lateral 
appendages. 
9.—Connecting membrane of same. 
10.—End view of ditto. 
11.—Side view of ditto. 
12.—Enlarged view of lateral processes. 


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