REMARKS ON SPINAL GANGLIA AND NERVE-FIBRES.
377
The nuclei already stained by the haematoxylin are made of
a richer colour, while the protoplasm surrounding them is
much bluer than the nuclei themselves. In the cerebellum
the effect is particularly good, the medullary substance being
of a rich purple, and the cortical substance of a pale blue,
but showing the cells with remarkable clearness.
Some REMARKS on SPINAL GANGLIA and
NERVE-FIBRES.
By JEREMIAH MCCARTHY, F.R.C.S. Eng., Lecturer on
Physiology at the London Hospital Medical College.
(With Plate XXII.)
I HAVE recently, in examining preparations of spinal
ganglia, observed some structural details which were new to
me, and to which I wished to direct attention. But, on consulting the abundant literature on the subject, I find that
nearly all the points have been anticipated by other observers.
Still, as the mode of preparation which I have used brings
out these structural details very clearly, and as my investigations were made in ignorance of the recent discoveries, my
independent corroboration of them may not be uninteresting
to readers of this Journal.
I have used as material the spinal ganglia of dogs, and
prepared them in the following manner:—The animal having
been killed, the ganglia were at once taken out and kept in
2 per cent, solution of mono-chromate of ammonia for three
weeks, and, the solution having been changed once or twice
during that time, were then transferred to methylated
spirit. After a few days longer they were ready for section.
The sections were stained with hsematoxylin, and were finally
mounted in Canada balsam solution. Sections so prepared
form very beautiful microscopic objects, as there is no
shrinking or disturbance of the relation of the tissues.
The surface of the ganglion is covered by a thick layer of
fibrous tissue, which contains numerous blood-vessels and a
little fat. From this processes pass into the ganglion, and,
there ramifying, form a delicate meshwork for the nervefibres or blend with the capsules of the ganglion-cells. The
ganglion-cells are very unequal in size, the largest being five
or six times the size of the smallest, and between these extremes are numerous gradations.1 These cells are arranged
1
With Hartnack's No, 2 micrometer ocular, and No. 8 objective, some
of the largest cells measure OO
' SO m. in diameter, some of the smallest,
0014 m.
378
JEREMIAH Ju'CAKTllV.
in clusters and sometimes in spindle-shaped groups, the long
axis of which corresponds to the long axis of the ganglion.
Occasionally a solitary ganglion-cell may be seen, but this
does not appear to be interposed in the course of a nervefibre, as some writers describe, but rather to result from the
section having passed through a terminal cell of one of these
spindle-shaped groups. Each cell is bounded by a very
sharply denned border, in which nuclei of connective-tissue
corpuscles may be distinguished. Within this is a broad
band of apparently hyaline substance with nuclei imbedded
in it. This hyaline layer is broadest where a nucleus is
situated, in parts where there are no nuclei becoming about
one third narrower. Examined with a No. 11 immersion
Hartnack, it appears faintly fibrillated. The nuclei are
mostly round, but some are oval, and in each of them a
nucleolus and some granules may be seen. With hcematoxylin they assume a pale violet colour, thus presenting a
marked contrast to the nuclei of the outermost layer of the
capsule, which take a much deeper tint. The number and
arrangement of these nuclei are variable. In some capsules
there are only three or four such nuclei, in others of equal
size, eighteen or twenty. Again, they are sometimes isolated,
sometimes in pairs, either overlapping or barely separate, and
sometimes in groups of seven or eight; this last arrangement
being most frequently seen at the junction of a nerve with
a ganglion-cell, where the section admits of such continuity
being traced. This hyaline layer, in most cells, has no definite limit internally, but shades off into a cloudy substance,
which in turn is continuous with a molecular mass, in which
is imbedded a very large nucleus. This molecular mass is
not the same throughout. Internally it often appears faintly
fibrillated, concentrically with regard to the nucleus, while
externally it has a more granular appearance, these granules
also being concentrically arranged, and is of a darker colour.
This outer part very usually contains a large irregular group
of pigment-granules. The nucleus has a very definite membrane, and is composed of some very finely granular matter
with a few larger granules and a nucleolus. On careful examination some differences may be detected in the nuclei of
different cells. In some of the smallest ganglion cells the
nuclei have a more compact appearance, and stain of a pale
violet colour, so as, but for their larger size and sharply
denned borders, to very much resemble the nuclei of the
hyaline layer. In some of the larger cells the nuclei, on the
contrary, have an almost vesicular appearance, are quite
colourless, and the nucleoli are unstained, shrivelled, and
ltlSMARKS 01* SPINAL GAN&LIA AN']) NERvE-VimiES.
379
like pigment-granules. Between these extremes numerous
gradations can be seen, but it must be stated that the condition of the nucleus does not seem to depend upon the size
of the cell, as colourless vesicular-looking nuclei may be
found in some of the smallest cells. In cells where the
nuclei become stained the surrounding substance appears
more homogeneous, and also assumes a pale violet, tint. In
no instance have I ever seen more than one nucleus in a
ganglion-cell.
The differences in the appearance of the nuclei suggest the
conjecture that ganglion-cells may be regenerated from this
nucleated hyaline substance. This conjecture is supported
in some degree by the position of the smaller cells, which
often seem as if they had been buds growing from the larger
cells with which they are in contact. It is further supported
by some observations of Mayer, quoted in Canstatt's ' Jahresbericht' for 1874, p. 45, who states, as the result of examination of frogs, toads, and tritons, that the so-called nuclei of
Schwann's sheath of peripheral nerves are originally large
nucleated cells lying upon the inner surface of the sheath,
and that as they participate in the regeneration process of
the nerve they probably belong to the nerve-tissue. As I
have been unable to obtain the original paper, I do not know
on what ground Meyer assumes that these cells are concerned
in the regeneration of the nerve; but if his assumption be
correct it would apply equally well to the nucleated interior
of the ganglion-cell capsule, which is analogous to the cells
described by him on the interior of Schwann's sheath.
The existence of nucleated cells on the interior of the
capsule of ganglion cells has long been known. Kemak,
quoted by Scliwalbe in Max Schultze's ' ArchivJ for 1868,
p. 58, describes these capsules as composed of a soft celllayer and of a firm membrane; Wagner and Hobin, quoted
by Fraentzel in Virchow's ' Archiv' for 1867, p. 557 ; Valentin, in Mtiller's 'Archiv,' 1839, p. 139; Henle, in his
'General Anatomy;' and Kblliker, in his ' Gewebelehre,'
1867, p. 250, describe and figure such cells; but the illustrations poorly represent what the appearance is as seen in
preparations made in the manner above described. Fraentzel
(loc. cit.) has by nitrate of silver demonstrated that this layer
is composed of epithelial (? endothelial) plates, and in this he
is corroborated by Schwalbe (loc. cit.) and Arndt (Max
Schultze's 'Archiv,' 1874, p. 140). The difference as to
the number of nuclei in the corpuscles of different cells has
been noticed by both Schwalbe and Arndt. The latter
regards the greater number of nuclei as the result of the
3$0
MCCARTHY ON SPINAL GANGLIA.
persistence of an embryonal condition, and that where there
are few nuclei the embryonal cells have become transformed
into connective tissue of a fibrillar character. To me, on the
contrary, it appears more probable that the larger number of
nuclei are the result of proliferation of previous nuclei. See
figs. 1 and 11.
The nerve-fibres run in a very irregular manner through the
ganglion, so that a section of the ganglion shows the fibres
cut, some transversely, some obliquely, and some longitudinally. Ranvier's constrictions in the sheath of Schwann
can be very distinctly seen, and the nuclei often appear more
within than in this sheath (cf. Mayer's observations). The
medullary sheath appears to be composed of small rods
radiating from the axis cylinder to the sheath of Schwann.
The arrangement of these rods, as seen in transversely cut
nerve-fibres, is not always the same. In some the entire
space between the axis cylinder and the sheath of Schwann
is occupied by these rods, while in others the rods appear
shortened, and also compressed laterally into bundles imbedded in some homogeneous substance. Again, in longitudinal sections, the appearance varies according to the place
of section. If the section has passed exactly through the
centre of the fibre these rods appear in a regular line and at
right angles to the axis cylinder; but if the section has
not passed through the centre, then these rods, being cut at
various angles, produce a cloudy or stippled appearance.
Reference to the accompanying illustrations, for the very
beautiful and accurate drawing of which I am indebted to
the kindness of Dr. Klein, will enable the reader to better
understand my description.
The regularity of the arrangement of these rods, as seen in
some longitudinal sections of nerve-fibres, is very suggestive
of the appearance of striated muscle. In the Sydenham
translation of Strieker's ' Histology,' vol. i, p. 161, Dr.
Grandry is said to have observed in naked axis cylinders, as
well as in those enclosed in a medullary sheath after treatment
with nitrate of silver, fine transverse striations of such regularity as to remind' the observer of the structure of striated
muscle. If this description be correct, it cannot refer to the
structure which I describe, which is most unquestionably in
the medullary sheath. Lautermann (' Centralbl., f. d. Med.
Wissensch.,' No. xlv, p. 706, 1874) is inclined to agree with
Stilling in regarding the medullary sheath as composed of
small tubulesj and then makes very brief allusion to rod-like
bodies, such as I describe, seen by him in osmic acid
preparations. Reference to the descriptions and illustrations
ON A PINK-COLOURED SFIRlLLVM.
381
in Stilling's elaborate work (r Untersuchungen ii. d. feineren
Bau. d. Nervenprimitivfaser,'&c.,1856) will, I think, convince
the reader that there cannot be any possibility of confounding
these rod-like bodies with the interwoven and anastomosing
tubules described by Stilling. He makes numerous quotations, proving that Fontana, Valentin, Ehrenberg, Kb'lliker,
and many others have remarked in the coagulated medulla
irregular masses, which with various reagents showed rods
either single or united in a retiform manner ; but in no publication have I been able to find anything corresponding
to what I have described and figured as the arrangement
of these structures.
I t may be objected that this striation is artificial and the
result of the reagents employed. To this I would reply (1)
that the great regularity of the appearance is opposed to t h i s ;
(2) that Heidenhain, who was the first to employ monochromate of ammonia, discovered the very similar condition
of the protoplasm of the epithelium of the convoluted portion
of the renal tubules, so that if the striation be artificial in the
one case, it must be artificial in the other case also; and (3)
the fibrillation of the mass of the ganglion-cells seen in these
preparations has hitherto been observed chiefly in fresh
ganglion-cells treated with iodized serum; so that the preservation of this, which seems to be the natural unaltered
state of the ganglion-cell, would be a strong presumption m
favour of the described striation also being non-artificial.
I am still, however, investigating the matter, and publish
this in order to direct the attention of histologists to the
point in question, and to the advantages of this mode of
preparing spinal ganglia.
N O T E on a P I N K - C O L O U K E D S P I R I L L U M
roxaceum).
{Spirillum
By Dr. E . K L E I N , F.R.S.
O N the 26th December of last year Dr. Mackellar, of the
Fever Hospital at Stockwell, placed for me a small quantity
—about half a drachm—of fresh faecal matter, obtained from
a recent case of enteric fever, in a bottle containing about
four ounces of water. The sediment, which was of a yellowishwhite colour, contained, when examined under the microscope, very numerous, bright, highly refractive, large (spherical) Micrococci, either isolated or in dumb-bells, or forming
smaller or larger masses of Zooglcea.