132
NOTES on
E. A. SCH£FER.
the * STRUCTURE
and
DEVELOPMENT of
OSSEOUS
TISSUE. By E. A. SCHAFER. With Plates VII and VIII.
{From the Physiological Laboratory ofUniversity College, London.)
I. The lamella of bone.—That the lamellae when stripped off
from a bone that has been softened in acid but subsequently
completely freed from all traces of the acid by long steeping in
water or spirit exhibit under the microscope an appearance of
intercrossing fibres (the reticulating fibres of Sharpey), is a
familiar fact to every student of histology in this country. But
in spite of its obvious importance and of the ease with which
the fact can be demonstrated, it has been, if not actually denied,
at least ignored by Continental writers almost without exception.
It is not, however, only in preparations of decalcified bone
that these fibres may be observed, nor does the fact of their
existence depend upon the appearances seen in a lamella when
viewed on its surface; for the assumption of the existence of
fibres in the lamella affords the only rational explanation of
what is seen in a sectiou of the bony layers made perpendicular
to their surface. In such a section, taken we will suppose for
simplicity of description across a Haversian system, we find
concentric rows of angular dots which are embedded in a homogeneous substance, an appearance of alternating granular and
clear zones being thus produced. Sections of the flattened cellcavities (lacunae) occur here and there in the clear zones, but
except where the lacunse are present the homogeneous osseous
substance is continuous throughout the Haversian system, being
only partly interrupted by the concentric rows of angular dots.
The question therefore arises, What in the section shall be taken
to represent a single lamella ?
Before endeavouring to supply the answer, it will be well to
consider the opinions of previous authors who have given special
attention to the subject. Sharpey described the appearances as
follows •}—" In a thin transverse section of hard bone the concentric lines, or rather bands, which represent the cut edges of
the lamellae, generally present with transmitted light a dark
granular-looking, and a light, transparent, and usually narrower
zone. . . . In a decalcified section the dark part shows a multitude of short bright lines running radially across it, with dark
angular particles between them . . . the appearance of dark
particles seems to be produced by the cut ends of the reticulatl Quain's 'Anatomy,' seventh edition.
ON THE STRUCTURE AND DEVELOPMENT OK BONE.
133
ing fibres of which the lamellae are made up. A longitudiual
section of the bone presents a corresponding appearance, for as
the fibres run more or less obliquely to the axis of the bone,
they present cut ends in a longitudinal section also. I t thus
appears that the animal basis of bone is made up of lamellae
composed of fine reticulating fibres. . . . "
I t would seem,
therefore, that although Sharpey notes the existence of clear
zones alternating with the granular or fibrous zones, he does
not attach sufficient importance to them to reckon them as an
integral part of the lamella.
Kanvier1 describes a section of hard bone as showing " deux
especes de lamelles qui alternent l'une avec l'autre pour former
les couches successives; les unes homogenes . . , les autres
d'aspect strie'. . . . II est facile de se convaincre que 1'aspect
strie* d'une des especes de lamelles est du a- de petits ponts 5.
bords siuueux, formes d'une matiere semblable a. celle des
lamelles homogenes.
"Oette structure des lamelles osseuses se voit aussi bien sur des
coupes longitudinales que sur des coupes transversales. 2 . . . "
I t is clear that this represents little more than a reproduction of Sharpey's original description. The facts are the same,
but the deduction as to what constitutes an osseous lamella is
different, and there would obviously be in a given thickness,
according to Ranvier, twice as many lamellae as would be
enumerated by Sharpey.
In order to arrive at a more exact definition of a lamella, it is
necessary to compare the structure of bone with that of the
other lamellated tissues to which it is most closely allied in
essential structure, especially some of the forms of connective
tissue. Of these that composing the cornea affords the most
striking analogy in structure to osseous tissue. Thus, the cornea
is composed of a number of lamellae which can be separated
from one another, and which are made up of fibrillated bundles
united together in the same lamella by a homogeneous ground
substance which also serves to bind together adjacent lamellae.
This interlamellar ground substance is partially occupied by the
1
' Traiti Technique,' p. 314.
* Ranvier goes on : " Oela prouve que la striation est r^ellement produit
par des petits ponts, et non pas1 par des lames longitudinales, com me on
pourrait le eroire si I'a3pect strie ne se montrait que sur des coupes transversales." Is not Sharpey's explanation, that the fact of the same appearance being seen whether the section be transverse or longitudiual is owing
to the oblique direction of the intercrossing fibres, a far more reasonable
one? But M. Ranvier cannot admit the existence of such fibres: "Nous
avons essayd le proc6d6 indiqu6 par l'auteur (Sharpey), mais nous n'avons
pas rdussi a voir la texture fibreuse dont il parle!"
134
E. A. SCHAfUR.
cells of the tissue—the corneal corpuscles—contained in special
cell-cavities, which are flattened conformably with the lamellae,
and which serve in sections of the cornea to indicate the limits
of adjoining lamellae. Comparing with bone, we find in the
latter also layers of fibres united by a homogeneous groundsubstance, in which are seen between the several layers cellcavities or lacunae containing the cells of the tissue flattened
conformably with the layers between which they lie. A further
analogy of structure is to be found in those fibres which in the
cornea pass obliquely, uniting layer to layer; more especially
the almost vertical " binding" fibres which pass through the
superficial lamellae towards the outer surface; for these, from
their position and general appearance, may without much effort
of the imagination be looked upon as representing the perforating fibres of bone.
The chief point of difference, leaving out of account the
chemical constitution of the two tissues, is to be found in the
fact that in the cornea the fibres in a lamella run in the same
direction, while in bone there are two sets of fibres which intercross with one another and are generally fused together at the
places where they come in contact. There is, however, sufficient
in common in the structure of the parts to enable a clcse comparison to be made. Since in sections of the cornea therefore
we speak of the lamellae as being separated from one another by
the flattened corpuscles, and in this way define a lamella as a
layer of fibrillated bundles closely held together by a homogeneous ground-substance which also covers the surfaces of the
layer, so in bone we must similarly define a lamella as a layer of
reticulating fibres covered on both surfaces by a homogeneous
substance, which extends between the fibres. It is clear
that in each case the homogeneous substance will only be distinctly visible in sections across the lamella?; in strip-preparations in both cases the lamellae seem almost entirely composed
of fibres. Further, since the corpuscles are in neither case
epithelioid, i.e., do not fit together by their edges after the
manner of epithelium-cells, gaps are left between the adjacent
cells, and these gaps are occupied by the homogeneous groundsubstance which serves to unite the lamellae to one another.
So that apart altogether from any special fibres that may pierce
the lamellae, or that may pass across from one lamella to another,
the lamellae are never entirely distinct from one another, which they
would be were the cells actually epithelioid; as for example, is
the case with those covering the connective-tissue tunics of the
Pacinian corpuscles. They allow of being stripped away from
one another in bone, in consequence of the presence of the cellcavities (lacunae) in strata between the lamellae, in the cornea,
ON THE STRUCTURE AND DEVELOPMENT OF BONE.
135
in consequence of the soft nature of the interlamcllar groundsubstance as compared with the fibrillated bundles of which the
lamellae are mainly composed.
We are led therefore from these comparisons to the conclusion
that each lamella of bone consists of a layer of fibres crossing
obliquely iu two directions, covered on both surfaces by and
embedded in a homogeneous ground-substance, which is continuous between the fibres, and also fused with the ground substance of adjoining lamellae; the planes of separation between
the lamellee being in the fully-formed bone indicated by the
presence of the flattened lacunee.
II. Nature of the Perforating Fibres of Sharpey,—It is now
generally admitted that the perforating fibres agree in their
general appearance and intimate structure with the bundles of
tendon or ligament, with the exception, of course, that they have
undergone calcification. This view is further strengthened by
the fact that many of them are to be traced directly from the
fibrous tissue of the periosteum:' moreover, as Kanvier has
pointed out, wherever a tendon or ligament is inserted into
bone, the bundles of fibres of the tendon or ligament are continued into the bone as perforating fibres. On the other hand
it is to be remarked that the latter differ from tendon-bundles in the fact that they are. not overlaid by flattened cells. In
micro-chemical reactions also the ordinary perforating fibres of
Sharpey agree with tendon-bundles, swelling up with acids
and so on. Heinrich Miiller, however, remarked that some of
the perforating fibres were of the nature of elastic tissue, basing
this opinion chiefly upon the resistance they offered to the action
of acids. My present purpose is to show how these elastic perforating fibres can readily be distinguished in situ, and differentiated from those of the white variety.
The process consists in staining sections of the softened bone
with magenta. This dye has a singular affinity for elastic tissue,
and it suffices to mount the sections, after every trace of the
acid which has been used to decalcify the bone has been washed
away, in a solution of magenta in glycerine and water. The fluid
should be only slightly coloured, and the edges of the coverglass
must be at once cemented so as to prevent evaporation of the
water. This is necessary, because concentrated glycerine redissolves any of the colouriug matter that has been deposited in
the tissue, and for a similar reason it is not possible to use an
alcoholic solution.
1
This by no means applies universally, for groups are often to be found
which commence near the medullary canal, generally close to the circumference of a Haversian system, and the Bbres of which taper off before
reaching the periosteum. Vide Plate VII., fig. 1, pf.
136
•
E. A.
If any of the elastic perforating fibres are present in the
section they are brought very clearly into view, being stained of
a dark-red colour;1 whereas the general substance of the bone
is merely tinted of a rosy-red, and the white perforating fibres
are hardly coloured at all. It is not difficult in this way to
make out the number and disposition of those of the elastic
variety.
It is seen, in the first place, that they vary considerably in
number in different parts. In some sections it is difficult to
make out any, in others they are more frequent but run singly,
and can only be traced for short distances, whilst in some other
sections, as for instance in the one from which fig. 1 Plate VII,
is taken, they are very numerous, and run both singly and in
groups, generally but not always distinct from those of the white
variety, and, like these,2 being always found piercing the circumferential and interstitial lamellae, never those of a Haversian
system. They are also often traceable directly from elastic fibres
in the periosteum.
The groups, like those of the white bundles (Gegenbaur),
often run alongside blood-vessels (Haversian canals), which pass
in from the surface of the bone, and some may even appear to
pass into or emerge from such a canal. This may have given
rise to the idea that the perforating fibres were to be found
piercing the lamellae of Haversian systems. It should be noticed,
however, that these canals near the periphery of the bone are
frequently not encircled by systems of concentric lamellae, but
merely lie between the circumferential lamellae.
The individual elastic fibres are always, in the human subject
at least, very much finer than the white perforating fibres.
Like the elasticfibresin connective tissue elsewhere, they constantly tend to branch and to unite by their branches with
neighbouring fibres. Their course is never straight but wavy
and often irregular through the bony substance; indeed, they
are sometimes singularly curled and contorted. This fact with
regard to the elastic fibres in bone casts doubt upon the notion
that in ordinary connective tissue the elastic fibres in their
natural condition always pursue a straight course, an opinion
which seems to have been based chiefly upon the examination
of stretched specimens.
III. Origin of the Intercrossing Fibres and of the Perforating
1
My attention was first drawn to this by Mr. W. Rushton Parker, oue
of 1the students in my class at University College.
lianvier, ' Trait6 Technique. So far as my observations have gone they
lead to an entire disagreement with Gegenbaur's statements aud figures as
to the relation of the perforating fibres to the lamellte of the Haversian
systems and to the lacunae.
ON THK STRUCTURE AND DEVELOPMENT OF BONE.
137
Fibres.—I am not aware that it has hitherto heen attempted to
identify the intercrossing fibres which are seen in the developed
osseous tissue with any of the appearances exhibited by bone
which is in progress of development. And this is scarcely to
be wondered at, considering that most writers have ignored the
very existence of those fibres. It. seems nevertheless surprising
that no one should have, at least so far as my knowledge
of the matter extends, offered any conjecture respecting
the destination of the osteogenic fibres, which are so characteristic of the true intra-connective ossific process. It is
generally assumed that by the extension of the calcific deposit
into them and by a deposit of a material similar to that of
which they are composed, upon and between them, they
become altogether blended, and that as distinct fibres they
are entirely obliterated. On the contrary, I would venture to
conclude that so far from this being the case the osteogenic fibres
persist as the intercrossingfibresof Sharpey}
In order to make clear the reasons upon which this opinion
is based, it is desirable that the mode of advance of the ossific
process into a connective-tissue membrane should be exactly
understood. We will therefore first of all consider the details
of the process as it proceeds in the membrane-skull and in the
perichondrium of the long bones respectively.
a. Ossification of one of the Membrane Bones of the Skull.—
The advancingedge of the growing bone is jagged in outline (Plate
VIII, fig. 1), the bony matter shooting out into the contiguous
membrane in the form of pointed processes, the so-called
" spicules," to which the deposit of earthy salts in the form of
minute globules gives a coarse granular appearance. Each
spicule is prolonged into the adjoining connective tissue by a
bunch of long, straight, unbranched delicate fibres, the osteogenic fibres. These themselves show an indication of fibrillation, and on this account and because of the similarity in
chemical constitution, they are regarded by Gegenbaur as
simply connective-tissue bundles of the fibrous membrane. It
is possible that they may pass into true connective-tissue
bundles at their further extremity, but this is by no means
certain, nor do I think that it has been ever clearly made out.
At any rate here, close to the advancing calcification, they are
quite different in general appearance from the connective-tissue
1
Not as the perforating fibres, as Clementi (in a paper which he has
published lately, and which he makes an ill-supported claim of priority of the
d
criticism of Kanvier's views as to the origin of the perforating fibres.
138
E. A. SCHAFEK..
bundles which overlie them, being in fact of a very characteristic aspect (Plate VIII, fig. 2). Their straight course and
their stiffness of aspect are alike remarkable; in these respects I
can only compare them to the fibres of which the basilar membrane of the cochlea is composed, and which are possibly of a
similar nature.
The osteogenic fibres of a bunch diverge from one other, the
intervals between them are occupied by the irregularly-shaped
osteoblasts. The fibres appear to be angular in shape, and the
ends of the osteoblasts are flattened and are applied to tlie
fibres which they lie between.
Since the osteogenic fibres diverge from the end of a spicule,
those which are situated laterally come in contact with the
similarly divergent fibres of the neighbouring bunches. When
this is the case their extremities may meet and blend, and
some of the fibres from one spicule may thus pass continuously
into those from another spicule (see fig. 2, Plate VIII). Bat
the majority do not thus blend, but pass across one another's
direction at a more or less acute angle, and thus present an
appearance of lattice-work like that of the intercrossing fibres
of perfect bone, except that in their present condition the fibres
are more distinct one from another. Meanwhile the calciuc
deposit gradually extends from the already calcified spicule into
the clear and soft osteogenic fibres and also into the osteogenic
substance which here cements the fibres together. The earthy
deposit may also make its appearance in isolated patches on the
fibres, a little in advance of the general area of ossification, but
these are soon united to the rest by an extension of the calcification along those parts of the osteogenic fibres which bridge
across the intervening space. In this way the first bony
lamella becomes formed, and while it is thus becoming extended
peripherally it undergoes a process of thickness pari passu at
its central part by a formation of other lamellae upon its surface.
These, like the first, are preceded by osteogenic fibres which
shoot out at numerous points from the surface of the bone
which is already calcified; they form in a similar way systems of
intercrossing fibres, and the earthy deposit gradually extends
itself along them and in the intervening soft osteogenic substance. While in this manner layer upon layer of the flat bone
becomes formed, two kinds of spaces are left, those which are to
become respectively the lacunse and the Haversian canals of the
bone. The mode in which these are produced has been so often
and so carefully described that it is unnecessary to dwell upon
it here. It is sufficient to remark that the Haversian canals,
large at first and enclosing besides a blood-vessel a quantity of
osteoblastic tissue, become gradually narrowed by the deposit of
ON THE STRUCTURE AND DEVKLOFMENT OP BONE.
139
layer after layer of osteogenic fibres in a concentric manner
upoa the wall of the space. Some of the osteoblasts, in their
containing lacunae, remain between tlie lamellae as the corpuscles
of the future bone, and since the lacunje are at first of considerable size they give the appearance of distinct gaps in the
osteogenic substance, which thus appears to form a network
upon the walls of the spaces which are to become the vertical
Haversian canals. This concentric deposit and the corresponding appearances just noticed commence already upon the sides
of the advancing spicule. Hence the osteogenic substance was
described by Sharpey as "spreading out at the sides of the
trabeculae and encroaching on the intervening space in form of a
bright trellis-work." In reality it is formed here in the same
way as elsewhere, namely, in the form of straight or curved,
stiff fibres applied to each other layer upon layer, and their
interstices occupied by a homogeneous substance which, as
well as the fibres, soon becomes infiltrated with calcareous
deposit.1
b. Periosteal Ossification of a Long Bone.—The mode of
advance of the ossific process in the periosteum of a long bone
is precisely similar to that seen in the skull-membranes. The
Part of section of developing tooth of young rat, showing the mode of
deposition of the dentine. Highly magnified, a. Outer layer of fully
formed dentine; b, uncalcifled matrix {odontogeri) with a few nodules
of calcareous deposit; c, odontoblasts, with processes extending into
the dentine; d, pulp. The section was stained with carmine, which
colours the uncalcified matrix, but not the calcified part.
1
It is interesting in comparing the development of dentine with that of
bone to note that in this case also the hard substance is preceded by a soft
material deposited in layers, and becoming subsequently infiltrated by calcareous deposit in the form of globules (much larger than those of osseous
development), which for the most part disappear as the intermediate
ground-substance becomes calcified. The main difference in the two processes is to be found in the fact, that in dentine there are no fibres developed in the ground-substance.
Since the soft material in which the
calcareous deposit of bone takes place is termed " osteogen," that in which
the calcification of dentine proceeds might be termed " odontogen."
140
E. A. SCHAFER.
periosteal bone is quite different in structural appearance and in
its behaviour to many staining reagents from the subjacent cartilage-bone, beyond which it is prolonged at either end of the
shaft for a little distance over the surface of the cartilage, so
that the formation of the periosteal membrane-bone always
slightly precedes the extension of the calcification of the cartilage
within.
This advanced part of the ossifying periosteum generally lies
embedded in a groove on the surface of the cartilage (Plate VII,
fig. 2)—the " encoche d'ossification " of Ranvier; and when
the ossification has progressed nearly to the end of the bone,
the advanced part becomes very much thickened and extends
deeply into the cartilaginous head. The appearance presented
i3 as if the periosteal thickening were eating its way into the
cartilage which is becoming absorbed before it; but it is possible that it may be produced by the lateral expansion of the
cartilaginous head over the end of the ossifying periosteal
tube.
Whatever may be the precise mode of its production the
appearance is very striking, as exhibited in the longitudinal
section of a bone the- shaft of which is far advanced in the
process of ossification like the one represented in fig. 2. The
groove formed by the advancing periosteal ossification is represented more highly magnified in fig. 3. It is here seen that the
tissue which occupies the groove is sharply marked off and
totally distinct from the cartilage itself. It includes no cartilage-cells at any part, but is chiefly occupied by rounded or
irregular granular cells (osteoblasts) amongst which are seen
a number of straight tapering fibres, which can be traced below
from the already formed periosteal bone. The tissue in question
is obviously not fibro-cartilage, as described and figured by
Ranvier.1 It encroaches on the cartilage and may possibly
be formed at the expense of the cartilage, but even if this be so,
there is no trace of the latter remaining in it. A few of the
fibres above mentioned may apparently be traced for a short
distance into the matrix of the cartilage, but these are exceptional, and are mostly met with in the superficial parts near the
fibrous perichondrium, the fibres of which, it is well known, are
generally traceable for a short distance into the subjacent
cartilage.
Respecting the delicate straight fibres which are seen in this
tissue, it has been observed that they are directly continued
from the bony matter which is already formed under the periosteum. .From this circumstance, as well as on account of their
general appearance and their osteoblast surroundings, it is im1
'Traits Technique,'fig.159, p. 450.
ON TflE STRUCTURE AND DEVELOPMENT OF BONE.
141
possible to regard them as any other than osteogenic fibres.
This was the view taken by Sharpey, who was the first to
describe the tissue in question, and who was led to the conclusion from the study of preparations torn or sliced from the
surface of the ossifying cartilage. In fact, in preparations so
made the appearance of the advancing ossification is almost precisely the same as that of the advance of ossification in the
parietal bone.1
Nevertheless, Ranvier has seen fit to re-christen these subperiosteal osteogenic fibres of the " encoche d'ossification"
with the name of " fibres arciformes." Moreover, he describes
them as being developed at the expense of the matrix of the
cartilage, and curving back from this to abut against the
surface of the newly formed periosteal bone, some even becoming embedded in the osseous substance and transformed into the
perforating fibres of Sharpey.
How M. Ranvier could have arrived at these conclusions I
am unable to conceive, unless he were misled by the examination of
sections winch did not happen to pass in or near the axis of the
b.)ne. The figure (fig. 3, PI. VII) represents with the utmost
fidelity the " encoche d'ossification " of the humerus of a catembryo, and it in no way corresponds to Ranvier's description.
Moreover, I have seen similar appearances in scores of sections
from growing bones of a number of different species of animals.
Sometimes bundles of connective-tissue fibres may be seen in
the encoche passing from the periosteum and crossing the direction of the osteogenic fibres (see fig. 2, PI. VIIjoy). It would
seem to he these that become the perforating fibres; the others,
I have no doubt, form here, as in the parietal, the reticulating
fibres of the perfect bone.
The extension of the bony substance by osteogenic fibres
which pass in bunches from the ends of the osseous points or
spicules and intercross with those from adjacent points can also
be seen in the transverse section of a growing bone (Plate VII,
fig. 5). Here the fibres spread out in all directions in the
osteoblastic tissue; they are totally distinct from the connectivetissue [fibres of the periosteum, which occur chiefly near the
outer surface of that membrane.
I am indebted for the careful and elaborate drawings from
which most of the figures which serve to illustrate this note
have been executed to the facile pencil of Mr. John Lawrence,
one of the students in my class of histology. To the faithfulness of the drawings as copies of the preparations I can testify ;
as artistic productions they speak for themselves.
1
See Quain's 'Anatomy,'fifthedition.
VOL. XVIII.
NEW SBB.
K
142
E. A SCHAFER.
Postscript by Dr. Bharpey.
DEAR SCHATER,—As I know you are about to publish the
results of inquiries you have lately been making into the structure and growth of bone, I am induced to ask you to give a
place at the end of your communication to the following remarks
which I desire to make on a note addressed to the Accademia
Gioenia of Catania by Dr. Clementi, professor in the university
of that city, purporting to show that the " perforating fibres of
bone," to which I drew attention in 1856, had been previously
described by two Italian writers on the structure of bone,
Domenico Gagliardi and Michael Troja.1
Gagliardi's work, entitled ' Anatomes Ossium, Pars prima'
(no second part followed), was published at Rome in 1689, and
his views on the structure of bone have often been referred to by
anatomists since his time. He considered that the compact
tissue of bone has a foliated structure, which becomes apparent
in bones—especially the tabular bones of the skull—which have
undergone desquamatiou by long exposure to the weather. The
layers into which they are thus resolved," squamulse or bractese,"
are coarse and rugged, and not to be confounded with the fine
lamellae now recognised by aid of the microscope, and Gagliardi
describes them as traversed by little osseous nails or pegs—
" claviculi"—which pin them together. These nails are held by
Dr. Clementi to be identical with the perforating fibres which I
have described.
Now, it is not easy to say what these claviculi really are;
probably, as suggested by Sappey, they may be little rolls of
concentric Haversian lamellae, which become dislodged from their
place; but, whatever be their nature, it is to be noted that they
are comparatively large objects, represented by Gagliardi as
visible to the naked eye in a figure he gives of a cranium (Tab. i,
fig. 1), reduced to a third of the natural size, and no more comparable to the perforating fibres than a broomstick is to a
bristle.
With greater justice, however inconsistent with his notion
concerning Gagliardi's nails, Dr. Clementi next refers to passages
to be found in a work of the Neapolitan surgeon, Michael Troja,
which really prove that the perforating fibres had been recognised
by that eminent Italian professor. Troja, in the last centurv,
acquired well-merited distinction on account of his admirable
experimental ' Essay on the Regeneration of Bone/ published
at Paris, in Latin, in 1775, and afterwards in Italian, with important additions, at Naples in 1779. After having been many
1
La Sooperta delle fibre dello Sbarpey rivendicata all' Italia. Nota
del Dottor Gesualdo Clementi, Professore pariggiate di Patologia speciale
chirurgia, &c, nella R. Uuiversita di Catania, 1875.
ON THE STRUCTURE AND DEVELOPMENT OF BONE.
143
years engaged in the practice of his profession, Troja resumed
his early work, and in 1814 published a quarto volume, entitled
' Osservazioni ed Esperimenti sulle Ossa, in Supplemento ad ua
Opera sulla Rigenerazione delle Ossa, iinpressa nel 1775 e nel
1779/ This volume contains the results of further inquiries on
the reparation of bone and observations on various diseases of
the osseous system, with finely executed figures, preceded by an
account of the intimate structure of bone in general, as studied
in the growing bones of the foetal cranium at different stages,
and in adult bones decalcified by means of phosphoric or nitric
acid; but no figures are given in explanation of the author's
histological descriptions.
Although aware that his distinguished countryman, Scarpa,
denied the lamellar structure of bone, Troja maintained its
reality as generally understood by preceding and contemporary
anatomists, inasmuch as he could split the compact tissue, after
decalcification, into layers—" piani fibrosi"—of greater or less
thickness, but not identical with the fine lamellae since recognised. The layers he describes as made up of fibrous bundles,
which he distinguishes into two orders—first, those of larger size
" fascifibrosidi prim' ordine"—which run longitudinally in some
bones, as the tibia, or radially, as in those of the calvaria, where
they form meshes by oblique lateral junction and by lateral offsets, " appendici," an appearance especially well seen in the
foetal head; and, secondly, finer bundles—" fascetti fibrosi di
second' ordine." These last cross the larger bundles in the same
plane or dip down into deeper strata, an arrangement which he
compares to the warp and woof of a web, and describes as visible
in the growing parietal of a foetus of three months, in which the
larger bundles appear as if encircled by fine transparent rings
formed by those of the second order. Clementi considers these
to be undoubtedly the perforating fibres, but to me this is by no
means clear. On the other hand, I cannot doubt that Troja did
truly recognise the perforating fibres, for he makes unequivocal
reference to them in the account he gives (p. 37) of the bands—
" legamentr"—by which the different layers are held together.
He explains that the different fibrous bundles already described
not only join each other laterally in the same layer, but serve to
bind together different layers, and thus describes the arrangement. In forcing asunder, he says, with the aid of a probe
flattened at one end, the concentric layers in a softened bone, the
offsets or appendices of the large fasciculi are seen crossing the
probe, and on introducing a finger between a partially detached
layer and the bone to which it belongs these appendices, still
entire, are seen passing from one surface to the other, but on
lurther pressure with the probe they break across with a faint
144
SYDNEY H. VINES.
crackling noise.
The fasciculi of the first order are distinguished by their aspect as well as by the great resistance they
offer to the probe, which may need to be aided by a few strokes
of a knife. The fasciculi of the second order are distinguishable by their fineness and the readiness with which they break.
They may be further recognised on membranous layers which
have been entirely detached, and which, though apparently
smooth, give to the finger when lightly passed over the surface
the sensation of numberless points so closely set together as to
feel like a fine brush. Moreover, when viewed with a magnifying power of 40 diameters, they are seen to be perpendicular to
the surface of the detached layer, whereas the broken ends of the
first order of fasciculi are not only larger, but lie flat on the
fibrous layer.
I cannot doubt, that the objects here described are really the
perforating fibres; at the same time, I cannot well conceive that
those I have met with, small and soft as they are, should feel
under the finger like the hairs of a brush, however fine.
Respecting Dr. dementi's note, I have further only to point
out that he is in error when he asserts, as he does (p. 12), that
I did not notice the existence of the, fibres in question in flat or
tabular bones; and, in conclusion, I cannot help saying that
when I first observed these fibres I had no idea that they bad
been recognized before, still less did I imagine that the subject of
my observation would ever acquire such importance as to lead to
a formal claim of priority on the part of Italian science.—Yours
faithfully,
E. A. Schafer, Esq.,
Dec. 1, 1877.
W. SHABEEY.
RECENT RESEARCHES into the NATURE of LICHENS. By SYDNEY
H. VINES, B.A., B.Sc, Fellow and Lecturer of Christ's College,
Cambridge.
IN previous volumes of this Journal,1 Mr. Archer has traced
the history of the discussion upon Schwendener's theory from its
commencement in 1868 down to the end of the year 1873. I
will endeavour to maintain the continuity by briefly alluding to
the principal papers which have appeared upon the subject during
the intervening years, reserving the more recent publications for
a somewhat detailed account.
1
Vols. xiii and xiv.