THREE MEMOIRS 
ON THE 
TEETH AND EPITHELIUM.  f£e r^eeZ/C 
R. C. 9. 
M'uc/m'e of Mle fffufi, emc/ ffevefo/iemcn/ of Jfjovy. 
/fuc-tut'e of Me Sname/. THREE MEMOIRS 
ON THE 
DEVELOPED!ENT AND STRUCTURE 
OF THE 
TEETH AND EPITHELIUM, 
BEAD AT THE NINTH ANNUAL MEETING OF THE BRITISH ASSOCIATION 
FOR THE ENCOURAGEMENT OP SCIENCE, HELD AT BIRMINGHAM, 
IN AUGUST, 1839; 
WITH DIAGRAMS 
EXHIBITED IN ILLUSTRATION OF THEM. 
ALEXANDER NASMYTH, F.L.S., F.G.S. 
MEMBER OF THE ROYAL COLLEGE OF SURGEONS, &C. 
LONDON: 
JOHN CHURCHILL, PRINCES STREET, SOHO. 
1841. LONDON : 
PRINTED BY G. J. PALMER , SAVOY STREET, STRAND. INTRODUCTION. 
In the early part of 1839, having the highest idea of 
the independence and utility of the British Association 
for the encouragement of science, and the fullest confi- 
dence in its protection and fostering care, I prepared 
three communications for its ninth meeting held at Bir- 
mingham, sparing no exertion to render them worthy 
of the occasion; and I have since been gratified to find 
that they have been regarded by many eminent physiolo- 
g.sts as important contributions to science, and have been 
recognized as throwing new light on the organization of 
animal tissues. As it has been, and I find from a recent 
publication, still is, industriously attempted to disseminate 
the most ridiculous errors and misrepresentations with re- 
spect to the nature of the theory of the formation of ivory 
embodied in these communications, and as many inquiries 
have been made for an authentic account of them, I think 
it best to publish the original materials of my communica- 
tions as they were delivered at Birmingham; and I ac- 
cordingly now proceed to lay before the public my papers 
as they were there read, my diagrams as they were there 
demonstrated, and the necessary remarks descriptive of 
the diagrams,—these remarks being printed within brackets 
at those parts of the papers where the diagrams were re- 
ferred to.* 
1 must premise, however, that the following papers 
were not written with a view to publication : though most 
of the facts which they contain are the results of long in- 
* The foot-notes in the following papers are, as will at once be seen, obser- 
vations which have been rendered necessary by the misrepresentations above 
mentioned. IV 
vestigation, and of frequently repeated observations; the 
papers were, nevertheless, hastily drawn up for the meet- 
ing at Birmingham, writh a full confidence in the generous 
encouragement of the body, under whose protection I sought 
to introduce them to the world. They are accordingly 
somewhat defective in style and arrangement, but the 
liberal and ingenuous reader, I have no doubt, will look 
over such defects, and also minor inaccuracies, in consi- 
deration of the nature of their origin, of the evidently 
uniform tenor of the whole, and of the spirit of candour 
iu which, notwithstanding all disadvantages, they are laid 
before the public. I need scarcely observe that the papers 
and the diagrams, taken severally, form but sections of 
the entire communication ; and that each section, having 
been prepared to accompany the other, gives necessarily 
but an incomplete idea of the whole: the diagrams are 
essential for the full comprehension of the papers, and the 
latter necessarily contain many passages embodying a de- 
scription of the diagrams. 
As Mr. Phillips, the editorial secretary of the Associa- 
tion, has informed me that ‘ I was at full liberty to publish 
elsewhere,’ (that is to say, besides in the Transactions of the 
Association,) c and at any time, the whole papers illustrated 
as I please,’ and as the Council itself has since distinctly 
confirmed the statement that the papers have always been 
and still are ray private property, the step w hich 1 at present 
take will not of course in the slightest degree affect the due 
publication of my own condensed report of these researches 
in the Transactions of the British Association—a report 
which was furnished at the request of the editorial secre- 
tary to the Association, wTas regularly approved and ac- 
cepted by him, and is thus, though it has not yet been 
delivered to them, the indefeasible property of the body 
of Associates. 
In consequence of the above-mentioned information con- 
veyed to me by Professor Phillips, I proceeded long ago to V 
make use of my original manuscripts in the prosecution 
of my researches, and prepared them for incorporation 
with the forthcoming second part of my work on Odon- 
tology, but my professional avocations have retarded its 
publication, which the proceedings of the Council of the 
British Association with regard to my communications 
have also impeded ; and indeed the retrograde movements 
of the Council in reference to the publication of a report 
of them, leave me at length no other alternative than to 
adopt the present course. 
No one can regret more than myself the necessity I am 
under of complaining of the conduct of the Council to- 
wards me in this matter; nor am I in the least disposed 
to indulge in acrimonious feelings against the enlightened 
members of that body, because I am confident that they 
had been improperly informed as to the circumstances of 
the case, when they first committed themselves to the line 
of conduct in which they have since thought it proper to 
persevere. 
Then, again, I am confident that had the official me 
chanism of the Association been in somewhat more perfect 
order, had the provinces of its respective functionaries 
been more distinctly marked out, and the communications 
of its officers with each other been more easy and frequent, 
the irregularities of which I have to complain would not 
have arisen. As it is, it appears to me that these irre- 
gularities have arisen from two steps taken in the 
first instance hy the editorial secretary, and from the 
Council itself having been induced for some reason to per- 
severe in the course thus commenced. 
The first of these irregularities was that mentioned 
above, of the editorial secretary, who, after having accepted 
the condensed report of my communications, which was 
drawn up at his request, abbreviated at his suggestion, after 
he had carefully examined it, corrected under his superintend- 
ence, and of which I afterwards received a hundred separate VI 
perfect copies, without any restriction as to the use I might 
make of them; nevertheless, without the authority qf any law > 
custom, or precedent, subsequently withheld it from pub- 
lication, merely because the accuracy of a paragraph of this 
report, which extended to eight pages and comprised a 
great variety of topics, was made the subject of ground- 
less comments by a member of the Council, he (Mr. 
Phillips) stating at the same time that he expressed no 
opinion as to the merits of those comments, though he 
was the very person whose office imposed upon him the 
obligation of doing so, were interference justifiable. 
In order to prevent him from thus abdicating his office 
in favour (or for the “ protection,” to use his own phrase) 
of an interested party, who, by inducing him to take this 
step, removed the question from the jurisdiction of the 
officer specially appointed to decide on such matters, to a 
tribunal of which he, the interested party, a member, 
and where accordingly he would sit as judge in his own case, 
I immediately offered, (although entirely released by Pro- 
fessor Phillips’own deliberate official acts just mentioned 
from any such obligation) at great inconvenience to myself j 
to carry to his residence at York, for his further satisfac- 
tion, the whole of the original materials of my communi- 
cations exactly as delivered at Birmingham ; and I may 
here state, that I have always been willing, and indeed de- 
sirous, to exhibit my communications, in an entire state, to 
any one who might wish to examine them. 
The next irregularity of which I have to complain is, 
that both Professor Phillips and the Council, which im- 
mediately afterwards took the matter into its own hands, 
not only did not accept this offer, hut never even alluded 
to it, and that the Council instantly proceeded, as if the 
offer had never been made, and without even exhibiting 
any charge, to instruct a committee to search for evidence 
on the accuracy of my own condensed report, not in the ori- 
ginal documents which I had instantly and spontaneously VII 
offered to exhibit, hut in unauthenticated reports of 
third parties in the weekly journals. Such a singular 
step evidently shows that the Council must have had at 
that time very erroneous or imperfect impressions on this 
matter; and it is quite impossible to credit that, had the 
Council been left to itself to form a deliberate judgment, 
it could have ever decided on totally disregarding my 
offer, and on committing itself at once to such an irre- 
levant course. The Council having been once induced to 
involve itself in an anomalous line of conduct, of which 
the direct tendency was to attempt to remove the question 
under consideration from its only natural sphere, and to 
place it upon altogether irrelevant grounds, no one can be 
surprised to find, that a series of objectionable and incon- 
sistent proceedings has flown out of these first measures; 
in complaining of which, as I am forced to do, my prin- 
cipal feeling is one of regret that the Council, which I 
am well aware cannot have been actuated by inimical 
feelings towards me, should, from some unfortunate causes, 
have permitted itself to be led into such a devious and 
unsatisfactory course. 
1 am hence, in proceeding to enumerate these proceed- 
ings, only influenced by a sense of duty, and have no 
wish to reproach the Council, which I am convinced has 
still the intention of doing justice to the Associates by 
restoring to them my report, which the acts of Professor 
Phillips have rendered their property, and of re-instating 
me in the enjoyment of my inalienable rights. 
In the first place, I think it very strange that though 
the authentic condensed report of my three communications 
has been withheld from publication, and an inquiry has 
been instituted with respect to it, no charge has, even to the 
present day, been exhibited against it, and no distinct 
object of inquiry recognized. Then, again, it has caused 
me no little surprise that the Council, though in the first 
place it spontaneously undertook an irregular inquiry, has viii 
since declared itself “ incompetent ” to prosecute it, owing 
to what it denominates “ the delicate physiological con- 
siderations ” which it involves. The Committee delegated 
to undertake the inquiry, and mentioned above as having 
been so singularly instructed by the Council, not only 
never availed itself of my offer to re-exhihit all my original 
documents, but had recourse, in the anomalous investiga- 
tion which it was appointed to carry on, to such evidence, 
in lieu of these original documents in their entire state, 
that it confounded, in its report to the Council, one subject 
of my investigations, viz. the formation of ivory, with 
“ dentition,” or the protrusion of the tooth through the 
gum, a topic never even hinted at in any of the three com- 
munications. 
Consistently with the impression which led to the 
declining of my offer above mentioned, both Council 
and Committee have persevered in neglecting even to 
acknowledge a mass of direct and positive evidence 
which, in my desire to assist them in obtaining a 
complete view of the case, I have been, in the course of 
our correspondence, at the trouble to submit to them. 
Several attempts have been made definitively to suppress 
the publication of my report; that is to say, to destroy 
what had been, by the deliberate, official acts of the 
Editorial Secretary, rendered the indefeasible property 
of the Associates, because the inquiry, it has been al- 
leged, could not be prosecuted to any definite result on 
the partial and limited grounds on which, in despite of my 
offer, it had been attempted to base it; though, according 
to ordinary principles of justice, such an abrupt termina- 
tion of the inquiry, without the proof of any allegation 
whatever against my report, ought instantly and indis- 
putably to ensure its publication. Finally, both Council and 
Committee, after insisting, exclusively, in the first place, 
on the unauthenticated reports of my papers published in 
the weekly journals, have, in the second place, confined IX 
themselves, in their pursuit of evidence, to intimating a 
request that certain portions only, specified by them, 
of my original communications, should be delivered up to 
them, though, as I have stated before, ray communications 
at Birmingham were threefold, consisting of papers, dia- 
grams, and observations descriptive of the latter ; though 
for these communications to be properly judged of, it is 
evidently necessary not only that all the materials should 
be present, but that each of them should be considered 
in its proper place; though I had previously volun- 
tarily offered to submit the whole of ray communications 
as evidence, without any reserve whatever, and though 
the only portions required were manuscripts, to which, as 
I have stated above, and as the Council and Committee 
have known from the very first, additions have been made, 
rendering them unfit to leave my custody. 
Surprised at the continued neglect of my offer above 
mentioned, both by the Council and Committee, as also at 
the plea of incompetency to judge the matter set forth by 
the former, and at the singular misconception already 
alluded to in the report of the latter, I at length, in my 
earnest desire to afford the fullest satisfaction, and to 
place the whole matter on an unexceptionable and natural 
footing, offered to refer the question, whatever its precise 
nature may be, and to submit the whole of my original 
documents to the President and Council of the Royal 
College of Surgeons, the only constituted body of ana- 
tomists in this country, and therefore the best tribunal 
for the decision of any physiological point; but, strange 
to say, this proposition, like my original offer to Professor 
Phillips, has been passed over in utter silence. 
Such have been the proceedings by which this un- 
fortunate transaction between the Council and myself 
has been characterized; and I feel that it is impossible 
for any one to consider them, without coming instantly to 
the conclusion, that an explanation of the irregular course X 
which the Council has been induced to adopt, can alone 
be found in some singular misrepresentation : at all events, 
it must be perfectly evident to every impartial mind, that 
had the matter been allowed to take its natural course, that 
is to say, had the editorial secretary or the Council fortu- 
nately consented to avail themselves of my original offer 
to submit the entire evidence on the subject, instead of 
the Council referring, in the first place, exclusively, to 
unauthenticated reports, and, in the second place, ex- 
clusively confining itself to requiring as evidence isolat- 
ed portions of the original manuscripts, selected at its own 
discretion, for the behoof of an inquiry, the object of which 
was never distinctly specified—I say, had the Council or 
Committee availed itself of my original offer, I think that 
not one of the strange irregularities which I have been com- 
pelled, with pain, to enumerate, could have arisen, and that 
even if my proposal to submit this question, involving 
“ delicate physiological considerations” to the Council of 
the College of Surgeons for its decision had been ac- 
ceded to, the whole matter would have been easily, 
speedily, and satisfactorily settled, 
I may here state, however, that in fact all inquiry on 
the subject, leaving out of the question its evident irregula- 
rity, was quite superfluous, for the accuracy of my own 
condensed report had been, some time before the Council 
entertained the question, satisfactorily vindicated in the 
Lancet, Medical Gazette, and Dublin Medical Press, 
by a reference exclusively to the unauthenticated reports of 
my communications published in the Literary Gazette 
and Athenaeum. In the Lancet for 1839-40, vol, ii. p. 
644, the editor states,—“ Mr. Nasmyth has demonstrated 
“ in the clearest manner that he was acquainted with, 
“ and had published, an account of the organised nature 
“ of the teeth long before the month of December, 1839; 
u and, furthermore, that he considered the teeth to be 
“ developed ‘ by a transition of the pulp cells [at, not on XI 
“ the external surface) into the cells of the ivory.’ ” . . . . 
“ The essence of the theory evidently is a transition of 
“ pulp cells into ivory cells; and this essential element 
“ is developed in the papers of Mr. Nasmyth, which 
“ were published fourteen weeks before the presentation 
“ of Mr. Owen’s memoir to the Academy of Sciences.” 
In the Medical Gazette for 1839-40, vol, ii. p. 593, is 
the following passage. “ He (Mr. Owen) will never suc- 
“ ceed in convincing a single rational being that Mr. Nas- 
“ myth, in the papers from which we have quoted above, 
“ (viz. the reports in the Literary Gazette and Athenaeum,) 
“ teaches the old doctrine of secretion or exudation of the 
“ ivory from the bulb, in contradistinction to Mr. Owen’s 
“pretended ‘ nouvelle theorie’ that the ivory is formed 
“ by the transition of the pulp to an ossified state.” 
The Dublin Medical Press says, in its No. for August 
19, 1840, p. 121,—“ We have now given the substance of 
“ Mr. Nasmyth’s researches and discoveries, as related in 
“ the report of his papers published in the Literary Ga- 
“ zette of Sept. 21, 1839, and in the Athenaeum of Sept. 
“ 14, 1839. The most careless reader cannot cast his eyes 
“ over these reports without perceiving at once that they 
“ attempt to establish the vesicularity or cellularity of the 
“ pulp, and its conversion into the cells and fibres of the 
“ ivory by the deposition of osseous matter.” 
As a specific and direct confirmation of the above public 
testimonies to the consistency of my opinions, it was with 
great pleasure that I was able to submit to the Council the 
following documents, which contain an account of the 
nature of my communications drawn up by three eminent 
physiologists, who saw them before 1 took them to Birming- 
ham, and consequently before there could be any motive 
for misrepresentation ; but I am sorry to say that even the 
receipt of them, as was the case with the other gratuitous 
aids to inquiry which I have afforded, has never been 
acknowledged: xii 
6, Holies Street, March 17, 1841, 
As you have asked me to stale my recollections of a 
visit to your house for the purpose of seeing your diagrams, 
and hearing your demonstration of them prior to your visit 
to Birmingham in 1839, I can have no hesitation in 
complying with your wish. 
On the afternoon of the day immediately prior to your 
starting for Birmingham, where you were engaged to read 
some papers at a Meeting of the British Association, on 
the minute structure of the teeth, I availed myself of your 
invitation, and met several gentlemen, amongst whom I 
well remember to have seen the late Sir A. Cooper, 
Mr. Liston, Mr. Burrowes, Mr. Gulliver, the Rev. Mr. 
Daniell, and one or two others. On the floor of your room 
were laid a great many very beautiful diagrams on various 
subjects connected with the developement of ivory, 
enamel, the pulp of the tooth, &c., as well as some on the 
microscopic characters of epithelium. You explained your 
views of these drawings, and read various extracts from 
the papers you were about to communicate to the Asso- 
ciation, and this meeting I considered as a private view 
to your friends, none of whom I believe were able to be 
present at the Association. 
I distinctly remember being struck with one particular 
diagram, which I then considered as demonstrative of the 
views you then expressed as to the conversion of the 
cells of the reticulations of the pulp into the cells of the 
ivory. In answer to several questions of Sir A. Cooper, 
who told us he had many years before attentively studied 
this subject with Mr. Fox, you controverted his opinions 
as to the formation of the ivory being simply an ossific 
secretion from a vascular pulp, and showed him the cor- 
respondence in figure and size between the cells of the 
ivory and those of the reticulations observed on the sur- 
face of the pulp, I recollect, also, most distinctly observ- 
My Dear Sir, xiii 
ing, in the particular diagram alluded to, that there were 
several leaf-like processes, which I could not help com- 
paring, in my own mind, with some of the fan-like coral- 
lines, which were coloured partly blue and partly yellow : 
you observed that the artist had in all the diagrams pre- 
served the same colour for similar structures; thus, in 
all, the yellow represented the ivory, and the blue the 
pulp. Upon being struck with the exact resemblance be- 
tween the yellow and blue portions of this drawing, we 
were informed that in the lighter parts (yellowish) the 
pulp cells were in a transition stage of change into ivory ; 
and in those more deeply tinted yellow, that change had 
been completed; and that the original curiously-arranged 
pulp cells had been converted into bone. There were 
several other diagrams more or less demonstrative of this 
fact, but I well remember to have considered, at that 
time, that this particular diagram distinctly demonstrated 
the facts you then tried to impress upon us, because of 
its representing in one view the successive changes from 
original pulp cells into the complete ivory of the tooth. 
My memory does not serve me as to whether the drawing 
was made from the human or some animal’s tooth, but I 
satisfied myself of the correctness of the artist as to the 
arrangement of the cells and the reticulations, by an ex- 
amination of a preparation which was placed under the 
microscope in another part of the room, which I examined 
immediately after Sir Astley Cooper, who expressed him- 
self satisfied of the fidelity of your artist. 
Yours faithfully, 
(Signed) 
John Dalrymple. 
A Nasmyth, Esq. 
I have read Mr. Dalrymple’s statement, and am able 
to confirm it in every particular; indeed, my recollection XIV 
of the transactions in question coincides precisely with Mr. 
Dalrymple’s narration. 
(Signed) 
George Gulliver. 
Hyde Park Barracks, March 17, 1841. 
I recollect perfectly the meeting at Mr. Nasmyth’s 
house above referred to, and T have the same impression 
of what then passed as Mr. Dalrymple and Mr. Gulliver 
have expressed. 
(Signed) 
Rob. Liston. 
5, Clifford Street, March 17, 1841. 
In addition to all these distinct and unimpeachable pub- 
lic and private testimonies regarding the nature of my re- 
searches, I have still another witness to call, and his 
evidence cannot, like the above, be passed over in silence 
by the Council, for he is no other than its own editorial 
secretary, Professor Phillips, who himself drew up a 
report of my communications, (the proof of which was 
sent to me under cover of a note from him, and is still in 
ray possession.) This report, with which I had nothing 
whatever to do, except that, on the very morning I first 
received it, having never heard of it before, I protested, 
by letter to Professor Phillips, against its insertion in the 
Transactions, on account of its brevity and inadequacy, was 
still accurate as far as it wTent, and contained the very pas- 
sages embodying that particular theory of the formation of 
ivory, on account of the presence of which, in my own con- 
densed report, Professor Phillips, that is to say, so far as 
I am able to understand his motives, withheld the latter 
from publication in the Transactions of the Associa- 
tion. As the Council, in the course of this transac- 
tion, has sanctioned an irregular and unprecedented act 
of the editorial secretary, (viz. in withdrawing from 
publication an officially accepted report,) in favour of XV 
another party, it will not, of course, refuse to recognise one 
of his ordinary proceedings, which happens unintention- 
ally, and therefore the more unimpeachably, to establish 
the accuracy of my own report. Professor Phillips’s notice 
of ray communications is as follows, and the statements 
above alluded to I have printed in Italics. 
u On the Structure of Fossil Teeth. By Alexander 
“ Nasmyth, Esq. F.G.S. 
u During the author’s microscopic researches in the 
“ structure of the teeth, he was led to the discovery of the 
“ organized nature of the interjibrous substance of the 
“ proper dental substance, which Purkinje, Fr'dnkel, 
“ Retzius, Muller, and others, have regarded as structure- 
“ less, and which he is disposed to believe is so cha- 
“ racteristic in different animals as to be capable of 
“ affording valuable aid in the classification of the animal 
“ kingdom. This structure he first observed in a section 
“ of a fossil tooth of a rhinoceros, by the aid of a mag- 
“ nifying power of one-tenth of an inch focal distance, 
“ with an acromatic condenser of the light. The section 
“ presented the appearance of cells or compartments, their 
“ form varying in different animals. The structure also 
“ of the fibres presented an interrupted or baccated ap- 
“ pearance, the divisions differing in size and relative 
“ position in various series of animals. The laminated 
“ concentric structure of the tusk of the mammoth, the 
c; strength of ivory, when cut parallel to the axis of the 
“ tusk, and its weakness if cut at right angles, are urged 
“ in corroboration of this peculiar structure. The struc- 
“ ture of the enamel, as seen in a section parallel to the 
“ axis of a tooth, exhibits compartments of a semicircular 
“ form, the convexity of the semicircle directed upwards 
“ towards the free external part of the tooth. From recent 
“ analysis by Dr. Thomson, the proportion of animal XVI 
“ matter proper to the enamel appears to have been much 
“ underrated. The pulp is observed to he cellular 
“ throughout its internal structure, and this structure is 
“ essentially concerned in the developement of the ivory, 
“ which is neither more nor less than the ossified pulp. 
“ There exists a great analogy between the internal or 
“ productive surface of the capsule and the external or 
“ productive surface of the pulp. The membranous in- 
“ vestment of the enamel in human teeth (lately discovered 
“ by the author) displays a similar arrangement. The 
“ crusia petrosa is provided with a membranous invest- 
“ ment. The whole of this paper was illustrated by 
“ numerous interesting diagrams. 
“ The subject of the developement of the ivory was 
“ treated by Mr. Nasmyth in a separate paper read before 
“ the Medical Section.” 
I now wdth confidence leave the reader to form his own 
judgment of the consistency of my opinions from the fol- 
lowing documents, the original materials of my communi- 
cations at Birmingham, and after an examination of the 
whole, he will learn with surprise, I think, that the only 
plea, so far as I can guess, for withholding my own con- 
densed report from publication in the Transactions of 
the Association, has been, that it contains the theory of the 
formation of ivory by ossific transition instead of by “ exu- 
dation,” which latter theory it has been ridiculously at- 
tempted to show that I supported at Birmingham ; and I 
think it must be evident that the Council, in indirectly 
favouring this attempt, by neglecting my original offer to 
afford full satisfaction in the only possible manner, as wrell 
as by totally disregarding all the unexceptionable evidence 
quoted above, has shown that it has been unconsciously 
biassed in its proceedings ; but I have no doubt that it 
will yet restore me to my rights, and deliver to the asso- 
ciates my authentic report, which is their indefeasible 
property. THREE MEMOIRS. **# The subjoined extracts from the correspondence of Pro- 
fessor Phillips, the Editorial Secretary of the British Association 
for the Encouragement of Science, contain the instructions in strict 
conformity with which I drew up a report of the following commu- 
nications for insertion in the Transactions of the Association. The 
passages to which I wish more particularly to call attention, I have 
placed in Italics. 
On the 10th of Febuary, 1840, I received from the Editorial 
Secretary the following note 
“ Professor Phillips begs to inform Mr. Nasmyth, that the ar- 
rangements for printing the volume of the British Association re- 
quire the very earliest possible transmission of abstracts of Memoirs 
read, to Professor Phillips. There can only be an abstract of Mr. 
Nasmyth’s paper, not requiring plates, but Mr. N. is at full liberty 
to publish elsewhere, and at any time, the whole paper illustrated as 
he pleases. Professor Phillips encloses the MS. as read in the Geo- 
logical Section, for Mr. Nasmyth’s guidance in making his abstract. 
“ There will he, of course, only one abstract, though the subject of 
the paper was treated in two sections.” 
In a subsequent letter, dated Launceston, Cornwall, April 4, 
1840, written after I had transmitted to him my own report, he in- 
formed me, that this report “ is to appear in the Proceedings of the 
Medical Section. On looking carefully over it,” he continues, “there 
seem to be a few parts capable of abbreviation; and as our rule 
of publication requires very close condensation of the communications 
to the sections, I return you the MS. with pencil-marks, proposing 
to you the omission of these few passages, to save space. They do 
not ajFect the substance of the Memoir.” <Z/iraofate o///e See/£ 
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London,, John, CkurchUL, Princes Street, Soh. MEMOIR No. 1. 
Investigations into the Structure of Fossil Teeth, Sfc. 
presented to the Geological Section of the British 
Association for the Encouragement of Science, at 
the Meeting held at Birmingham in August, 1839. 
By Alexander Nasmyth, Member of the Royal 
College of Surgeons, London, &c. &c. 
The modern science of Geology may be consi- 
dered the most comprehensive of all the branches 
into which human knowledge resolves itself. No 
progress can be made in any department of physical 
philosophy, which does not throw light upon its 
vast and wondrous domain, and exalt the brilliancy 
of its truths. Though it exacts a knowledge of the 
perishable portions of the animal frame, it is ob- 
vious that its advance chiefly depends on accessions 
of information respecting permanent animal relics 
which remain embedded in the crust of our globe, 
unaffected by the powerful chemical agents con- 
tained in the laboratory of nature. The skeleton, 2 
scales, and teeth of animals being the only parts 
which are found in a fossil state, it is evidently of 
paramount importance that the general character 
and internal structure of these should be clearly 
understood. Their external forms have already 
been well established, and the combined labours of 
eminent naturalists have left little to be desired in 
this department of science;—but natural revolu- 
tions, slowly but surely taking place, during the long 
march of time, whose steps the geologist is sum- 
moned to trace back to a period incalculably re- 
mote, have occasionally so mutilated these other- 
wise permanent remains of animals, that they retain 
none of the characteristic peculiarities of the species 
to which they belong. Here micrography comes 
to our aid ; and its able application to odontology 
by Retzius and others, so ably described to you last 
year by Professor Owen, has opened a new field of 
inquiry, which already promises the most brilliant 
results. Presuming that any additional researches 
in this direction cannot but be of interest to the 
members of this section of the Association, I hasten 
to lay before you a succinct account of my recent 
researches on the microscopic structure of the teeth. 
In endeavouring to form a classification of the 
animal kingdom, having for its basis the peculiar 
disposition and arrangement of the internal orga- 
nization of the teeth, I was led to the discovery of 
a structure, which has hitherto not been noticed. 
Purkinje and Frankel state that “ the proper dental 
substance consists of a uniform structureless sub- 3 
stance, and of fibres passing through it.” The 
writings on the subject by Retzius, Muller, and 
others, leave us to conclude that the interfibrous 
substance does not present any traces of peculiar 
conformation :—but I am disposed to believe that 
it is not only organized, but so differently and cha- 
racteristically so in different animals, as to be ca- 
pable of affording valuable aid to the naturalist in 
classifying the animal kingdom.# 
[In illustration of this subject, I beg to refer to 
the drawings, showing the characteristic varie- 
ties of this conformation [two of which, marked 
Fossil Ivory, No. 8 and 10, are engraved in PL 
C. 5, at the end of the present papers]. The beau- 
tiful characteristic varieties of this cellular confor- 
mation in different classes of animals, show the de- 
licate nature of the process of transition by which it 
is produced.] 
* It has been absurdly attempted to show that, in my papers 
delivered at Birmingham, I supported the old theory of the for- 
mation of ivory by “ excretion,” or “ exudation,” from the pulp. 
Neither of those words, however, occurs at all in my papers; 
and the corresponding ideas were equally absent from my 
mind. Moreover, the slightest reflection will convince even a 
tyro in anatomy, that the above simple announcement of a 
characteristic and in every case beautiful cellular organiza- 
tion of the interfibrous substance of ivory, is diametrically op- 
posed to such a theory. How could this organization be the result 
of a process of exudation or excretion ? In short, to speak of the 
excretion or exudation of ossified cells, is a ridiculous absurdity. 
When, on first entering upon my researches into the structure and 
formation of ivory, I discovered, by an examination of extreme!}' 
thin sections of the latter, the cellular arrangement of its inter- 4 
My attention was first drawn to the structure of 
the interfibrous substance on examining a delicate 
section of the fossil tooth of a rhinoceros, by the 
aid of a very high magnifying power; and I must 
here remark, that those who repeat these investiga- 
fibrous substance, I was compelled to conclude that this could 
only be prod uced by a process of transition which I then proceeded 
to trace. The results of my further inquiries will be given in the 
course of this memoir, but at greater length in the next. In 
connection with this subject may be examined PI.- A. 3, Fig 6, 
at the end of the appended series of plates: it is copied from 
Retzius, and shows in a tooth, which he says is that of the adult 
horse, the corpuscles, or cells, as he calls them, in which, and 
on which, according to him, the dental tubes terminate. These 
corpuscles or cells are the dark spots with lines radiating from 
them, in a manner similar to the corpuscles of true bone. They 
are only to be found, he states, towards the periphery of the 
tooth. It will be seen at once that they are altogether distinct 
from the interfibrous cells which I have described, though one 
writer on Odontography has, from unaccountable ignorance of 
the subject, or from some other cause, confounded them with 
each other; and has accused me of announcing, as my own dis- 
covery, that which had been previously published by the distin- 
guished Swedish anatomist. Neither in connexion with this plate, 
nor in any other part of his work, does Retzius ascribe any 
structure to the proper interfibrous substance : he only alludes 
to the corpuscles above mentioned, which he says are extremely 
minute, and scarcely demonstrable in human teeth, and to what 
he terms the ramifications of the tubes, as occupying a portion 
of the interfibrous spaces. How the corpuscles of Retzius can 
have been mistaken for the cells of the interfibrous substance 
which I have described, I think any one who compares the 
former, as delineated in PI. A. 3, Figs. 4 and 6, at the end of the 
series appended, with the latter as represented in Figs 8 and 
10 of PI. C. 5, will be at a loss to imagine. 5 
tions, the results of which I am about to detail, 
will find it necessary to make use of a magnifying 
power of one tenth of an inch focal distance, and 
of the most perfect kind, with an achromatic con- 
denser of the light. The instrument with which 
I have conducted my researches, and upon the 
accuracy of which I place the greatest reliance, 
is that of Mr. Powell.* 
In the section of the tooth of the rhinoceros 
to which I have just alluded, will be observed 
an appearance of cells or compartments. This 
I at first imagined might arise from fractures 
of the material, but on examining other sections 
of fossil teeth, examples of which are now ex- 
hibited, and at the same time seeking whether this 
cellular appearance could be observed in recent 
teeth, I was enabled to demonstrate that in every 
case this peculiar appearance was that of real struc- 
ture. 
The examples of this appearance in the ivory, 
both of fossil and recent teeth, which I now place 
* All the anatomical observations detailed in these memoirs 
were frequently repeated, were verified by the eyes of others, 
and the preparations were faithfully copied by my talented 
artist. It may require some practice, and a certain degree of 
proficiency in manipulation, to produce and examine such pre- 
parations of the pulp and ivory in the human subject; and some 
persons may perhaps be found, who, having been unsuccessful in 
making them, at once deny that it is possible for others to be 
more expert or fortunate ; but the fallacy of this will soon be 
evident to all persons of tact and perseverance who devote 
themselves to the subject. 6 
before you, are brought forward merely with a view 
to establish the general principle, that the organiza- 
tion of the dental bone is cellular, and they have 
been selected more from convenience at the mo- 
ment, and as demonstrating the variety of cellular 
conformation existing in the teeth throughout the 
wide range of the animal kingdom, than with any 
intention of establishing at once a complete and 
systematic view of the subject. 
I have also made researches into the structure 
and composition of the fibres of different teeth, and 
have generally found that these present an in- 
terrupted or baccated appearance, as if they were 
made up of different compartments,—an obvious 
concomitant of the cellular structure of the inter- 
fibrous material. The size and relative position of 
these portions or divisions of a fibre differ in va- 
rious series of animals. In the human subject, for 
instance, each compartment of the fibre is of an 
oval shape, and its long small extremity is in ap- 
position to the one next adjoining. The long axis 
of the oval corresponds with the course of the fibre. 
In some species of the monkey tribe the fibre ap- 
pears to be composed of two rows of compartments 
parallel to each other. In the orang utan the fibre 
is composed of rhomboidal divisions, and in the 
baboon they are oval like those of the human 
subject, and the surfaces of the long axes are in 
apposition. In fact, each class of animals seems to 
have a distinct characteristic appearance, but all 
are similar in respect to the general baccated 7 
appearance. A few examples of this structural 
arrangement are seen [at PI. C. 6,] in the 
diagrams marked “ Ivory deprived of earth,” 
Nos. 1 to 4, showing its appearance after the 
earthy matter has been removed. 
Among the gigantic remains which are brought 
under the consideration of the geologist, there is 
one which to me is particularly interesting—I 
allude to the tusk of the mammoth. As found in 
our museums, it will be observed to present a lami- 
nated, concentric structure, being apparently com- 
posed of layers gradually increasing in size from 
the centre to the circumference. These layers in 
numerous instances are separated from each other 
by considerable spaces. The experiments of Hunter 
on animals fed on madder also lead to the con- 
clusion that the structure of the teeth is actually 
laminated ; and the workshop of the mechanic, 
called by Professor Leslie the School for Philoso- 
phers, furnishes numerous facts in support of the 
same position ; for instance, the circumstance that 
ivory is found to possess considerable strength if 
cut parallel to the long axis of the tooth, and that 
it is weak if cut at right angles. If we suppose 
that ivory consists only of fibres surrounded by 
a structureless material, .passing from the centre 
to the circumference, we must conclude that at 
right angles to their course it would be most diffi- 
cult of fracture ; but the contrary is the fact, as is 
exemplified by the natural separation of the 
lamellse of the tusk of the mammoth in a direction 8 
contrary to the course of these fibres, as well as 
by the mode adopted by ivory cutters of making 
sections corresponding to the vertical, and not to 
the transverse diameter of the tooth. Many other 
facts might be here adduced, as well as phenomena 
accompanying the decay of these organs, were this 
necessary or relevant to the business of this section. 
All systems of dental structure which have hitherto 
been propounded have failed, I think, to explain 
facts of daily occurrence, but they may be accounted 
for, I venture to assert, by the cellular organiza- 
tion of the interfibrous substance which has been 
improperly termed structureless, and by the pecu- 
liar baccated arrangement of the fibres. 
According to the views of Retzius, Purkinje, and 
the recent investigators of the structure of the teeth 
by the aid of the miscroscope, the enamel consists 
of fibres running in a direction from the centre to 
the circumference of the tooth. Both Retzius and 
Purkinje have given delineations of the course of 
these fibres. On making a section of the enamel, 
in a direction parallel to the transverse diameter of 
the tooth, the appearance as described by these 
writers is observed, and they are said to be seen 
to terminate in an hexagonal form beneath the 
investing crusta petrosa. • If, however, a different 
section of the enamel of the human tooth be made; 
for instance, one near the surface, parallel to the 
vertical direction or long axis of the tooth, an 
appearance presents itself which has induced me 
to take a different view of the nature of the struc- 9 
ture of the enamel. The appearance to which I 
now allude is represented at [Plate C. 9,] figure 
marked Structure of the enamel, No. 1. It will 
there be found that the section of the enamel pre- 
sents compartments or divisions, but of a different 
character from those I have already spoken of as 
existing in the interfibrous substance of the ivory. 
Each compartment of the enamel is of a semicircu- 
lar form, and the convexity of the semicircle or 
arch looks upwards towards the free external por- 
tion of the tooth. The vertical section, [Plate C. 9,] 
enamel No. 2, gives the appearance of these cells as 
seen in that direction. 
In the sections both of enamel and ivory, there 
will be always observed near the margins isolated 
cells, which admit of their form and appearance 
being carefully studied. 
All the anatyses hitherto made of the chemical 
composition of the enamel lead to the conclusion 
that the structure contains only a very small por- 
tion of animal matter. But when I detected the 
cells or compartments just mentioned, I could not 
but infer that each of these had for its basis and 
support a frame-work of animal tissue; and I im- 
mediately requested my friend Dr. Thomson of 
Glasgow to favour me with a complete analysis of 
the teeth, and their different component structures, 
in their various states of health and disease. The 
results of this analysis, so far as it has been pro- 
ceeded with, are highly interesting; I present them 
to you in a tabular form, and you will observe how 10 
fully accordant they are with the position that the 
enamel is provided with an animal basis—a view 
my microscopic investigations had already corro- 
borated by various appearances.* 
Having thus uniformly found appearances de- 
noting cells or compartments in all these states and 
stages, I became doubly eager to investigate the 
structure of the pulp, with a view to discover the 
nature of the process by which this cellular struc- 
ture is produced, and the source from which it is 
derived. I might now enter upon a description of 
the organization of the pulp, and its relation to the 
process in question ; but as this is a subject of 
purely anatomical detail, I consider that it falls 
more particularly under the cognizance of the me- 
dical section of the association. Suffice it here to 
state, that the pulp is cellular throughout its en- 
tire structure, as may be seen from the series of 
diagrams placed before you, marked Structure of 
the Pulp, and Developement of Ivory, Nos. 1 to 16, 
(and contained in Plates C. 6, C. 7, C. 8, & C. 9.)f 
I at first experienced great difficulty in sub- 
mitting to minute examination the surface of the 
pulp; that is to say, that portion of it where its 
transition into ivory takes place; but I at length 
* To this table considerable additions have since been made, 
which are not yet completed; and I therefore, in justice to its 
eminent author, withhold it, until I am enabled to publish it 
in a perfect state. 
■f To avoid repetition, I beg to refer to the next Memoir, 
p. 27, for a description of these diagrams. 11 
succeeded in obtaining a clear view of it, and found 
it to present the beautifully interesting reticulated cel- 
lular appearance which is represented in the series 
of drawings marked Pulp, Nos. 6 to 16, [PI. C. 7, 8, 
and 9,] where the cells of the pulp in a state of tran- 
sition are coloured blue, and those ossified are co- 
loured yellow. 
Having ascertained that this reticular conforma- 
tion was gonstant in all the pulps which I examined, 
I proceeded to study it with confidence, and soon 
found that it was essentially concerned in the pro- 
cess of the developement of the ivory, and in the 
production of the fibres of the latter, as well as of 
the interfibrous substance. Of this part of ray 
subject I intend to treat more at length before the 
medical section, but some idea of the different stages 
of the formation of dental bone may be gained from 
an examination of the series of diagrams above 
alluded to, showing the transition of the cells of 
this reticular surface into the cells of the ivory. 
Conceiving that there existed a great analogy in 
the productions of the capsule and the pulp, I 
searched for the appearances displayed by the in- 
ternal or productive surface of that membrane, and 
found them analogous to the external or productive 
surface of the pulp, as shown in the drawing, [PI. 
C. 11,] No. 6. 
The membranous investment which I lately dis- 
covered as investing the enamel of the teeth of man 
and other simple teeth, displays a similar arrange- 
ment. 12 
Thus, there is a remarkable uniformity in the 
structure of the formative tissues of the tooth, and 
of the dental substance itself; for not only is the in- 
terfibrous material cellular, but the surface of the 
pulp, which is the organ for the production of the 
ivory, and the internal or productive surface of the 
capsule, also uniformly present a reticulated or cel- 
lular appearance. 
My researches have, I venture to hope, also 
established a new and beautiful instance of the har- 
mony of the laws of nature in demonstrating the fact 
of the uniformity of the products of the capsule ; 
for not only is the enamel uniformly provided with 
an external covering, but there is also a membran- 
ous investment of the crusta petrosa itself. I think, 
also, that we must be compelled to allow the uni- 
form presence of a fourth tooth-bone substance, the 
existence of which is more constant in all animals, 
either normally or anormally, than any of the other 
three hitherto recognized textures. But as all these 
subjects belong properly to the province of the me- 
dical section of the Association, I think it unneces- 
sary to allude to them more fully here. 13 
MEMOIR No. II. 
Investigations into the Developement and Organiza- 
tion of the Dental Tissues, Sfc., presented to the 
Medical Section of the British Association for 
the Encouragement of Science, at its Meeting held 
at Birmingham, in August, 1839. By Alexan- 
der Nasmyth, M.R.C.S., &c. kc. 
At the last meeting of this Association, the sub- 
ject of the structure of the teeth was entered into by 
Professor Owen, who detailed before this section 
more especially the investigations which have of 
late years been conducted in this branch of science. 
I must confess that I felt dissatisfied with some of the 
results of these investigations, contained in the writ- 
ings of Retzius, Purkinje, and Miiller ; and at the 
time that paper was read, I was endeavouring to 
arrive at a confident conclusion on the subject, by 
prosecuting a series of researches which I had 
commenced several years before, and which I have 
pursued uninterruptedly to the present time. 
I will in the first place briefly place before you 
the conclusions to which I have arrived on the fol- 14 
lowing subjects : 1st. on the Covering of the 
Enamel : 2ndly, I will communicate my own views 
on the Structure of Teeth; and 3rdly, I will treat 
succinctly of the Structure of the Pulp, and its rela- 
tion to the developement of the ivor}T. 
The researches of Retzius and Purkinje, so faith- 
fully detailed to you last year, have established that 
there enters into the composition of the simple and 
compound teeth of man and mammalia generally, 
not only ivory and enamel, but a third substance, 
the crusta petrosa, which had been noticed pre- 
viously on the free surface of the compound teeth 
of graminivorous animals. The crusta petrosa, as 
existing on simple teeth, was described to you, after 
Retzius, Purkinje, and Frankel, as a layer external 
to the ivory of the fang, but as not present on 
these simple teeth as a covering to the enamel. I 
should here mention, howrever, that Purkinje and 
Frankel state, that they had once noticed it coating 
partially the enamel on the tooth of an old man. 
My researches, however, have led me to the convic- 
tion, that the enamel itself possesses in all instances 
a distinct envelope or coating. On the incisor of 
the calf and several other simple teeth, I have also 
distinctly traced in this layer of crusta petrosa, 
superimposed on the enamel, the corpuscles of 
Purkinje, analogous to those found in bone. I 
possess preparations of teeth of the human subject, 
and simple teeth of the herbivora and carnivora, 
showing this structure in a clear and unequivocal 
form. The details of its discovery and of its anato- 15 
mical description may be found, by those who feel 
anxious to inquire further into the subject, in a 
paper of mine in the forthcoming volume of the 
Transactions of the Med. and Chir. Society, accom- 
panied by drawings. * 
At present, in order not to make inordinate 
demands on your limited time, I hasten to the 
next branch of my subject. In a paper which I 
have had the honour of submitting to the notice 
of the geological section of the Association, I have 
treated of the structure of the substance which in the 
dental ivory occupies the space between the fibres. 
I have proved, by a careful examination both of 
fossil and recent teeth, that the interfibrous sub- 
stance is not structureless, but that it presents a 
character so remarkably well defined as to furnish 
a most important and interesting accession to the 
odontographic basis for a classification of the ani- 
mal kingdom. 
I have selected specimens of these appearances, 
(seen in the diagrams, marked Recent and Fossil 
Ivory, two of which I have given at [PI. C. 5,] Nos. 8 
and 10,) not with any reference to the individual 
peculiarity of their arrangement, but merely be- 
cause the drawings of them are in a more con- 
venient and advanced state. 
I have also made researches into the structure 
and composition of the fibres of different teeth. 1 
have generally found that these present an in- 
* Here were exhibited and described the drawings contained 
in PI. C. 11 and 12 of the appended series. 16 
terrupted or baccated appearance, as if they were 
made up of different compartments. The size and 
relative positions of these portions or divisions of 
a fibre differ in various series of animals. In the 
human subject, for instance, each compartment of 
the fibre is of an oval shape, and its long, small 
extremity is in apposition to the one next adjoin- 
ing. The long axis of the oval corresponds with 
the course of the fibre. In some species of the 
monkey tribe the fibre appears to be composed of 
two rows of compartments parallel to each other, 
and a trace of the same appearance is evident even 
in some of the principal ramifications of the fibres. 
In the orang utan the fibre is composed of rhom- 
boidal divisions, and in the baboon they are oval 
like those of the human subject, and the surfaces 
of the long axis are in apposition. Some of the ap- 
pearances are seen in the diagrams [PI. C. 5,] 
marked ivory fibres, Nos. 3 to 6, where the ap- 
pearances of the fibres of the orang utan, loris, 
mandril, and cynocephalus, are shown. 
When teeth are submitted to the action of acid, 
for a period long enough to allow the earthy 
matter to be all taken up, I find that the animal 
residue consists of solid fibres, and if the decom- 
position be allowed to continue, these fibres present 
a peculiar baccated appearance. The drawings 
marked, Ivory deprived of Earth, [PI. C. 6,] Nos. 1 
to 4, show these appearances. 
[No. 1 shows the appearance of the ivory when 
the earthy matter has been almost entirely re- 17 
moved by acid, but where the cells still retain 
their position, general appearance, and connexion 
with each other. 
Diagram No. 2, represents a more advanced 
stage of decomposition, where there seem to be 
attached to each fibre minute lateral filaments, 
which I presume to be the remaining portions of 
the emptied cells. 
Diagrams No. 3, and No. 4, depict the appear- 
ances presented when decomposition has so far 
advanced as to have rendered the fibre interrupted 
or baccated. No. 3, represents the fibre of a 
human tooth, and No. 4, that of the elephant in 
this state. 
It may be useful to compare these cells in No. 1, 
after they have been deprived of their earthy con- 
tents, with their state previous to the reception of the 
earthy matter as delineated in pulp No. 6, A. 
&c. [PI. C. 7 and 8.] In the reticulations they are 
collapsed, lying one above another, but after having 
been deprived of earth, they will be observed to be 
rigid, and to retain the erect distended form which 
they acquired by the deposition within them of 
ossific matter.*] 
* To indicate the true theory of the formation of ivory, nothing 
more is required than the display of these appearances. No “ ex- 
creted” or “ exuded” substance can possibly present an animal 
tissue arranged in regular connected cells. It is quite evident that 
these cells, whilst receiving a supply of earthy matter during the 
process of transition, must remain in connection with, and in- 
deed continue to form part of, the pulp. It would be absurd to 
suppose that a regularly cellular structure can be “ excreted 18 
The general appearance of the fibres thus treated 
is exactly similar to that of the fibres of cellular tissue 
generally, and the diameter of each corresponds 
exactly to the diameter of the calibre of the tube, 
which, according to Retzius, is pervious, although 
at the same time he says that it is always more or 
less filled with earthy matter. In fact, the tubes 
have been said to be principally visible by means 
of their contents, the reason of which appears to 
me obviously to be, that these contents are the 
only part of them which actually exist. 
In order to separate the animal matter from the 
osseous substance of the tooth, I submitted thin 
slices of many different kinds of dental bone to the 
action of a solution of caustic potash, for a period 
sufficient to dissolve and remove the organic tissue ; 
but the brittle nature of the residue, the difficulty 
of washing it without breaking down its structure, 
and the great opacity of the sections which had 
been thus treated, deprived this experiment of any 
striking results illustrative of the internal orga- 
nization of teeth : but the appearances presented in 
its progress were all such as to favour the con- 
clusion that the structure of the ivory is essentially 
cellular. 
but it would be still more ludicrous to maintain, that after such 
cells have been excreted, that is to say, after all connexion 
between them and the pulp has ceased, they still possess the 
power or means of deriving from the blood the materials requi- 
site for their transition into ivory, and of carrying on that 
process in their isolated state. 19 
Having convinced myself of the existence of the 
peculiar cellular structure of the tooth, I entered 
with great interest on an examination of the organ 
by which it is produced, viz. the pulp. 
On examining the internal structure of the pulp 
generally, the number of minute cells presenting 
themselves in a vesicular form is very remarkable ; 
they seem to constitute indeed the principal por- 
tion of its bulk. These vesicles vary in size from 
the smallest perceptible microscopic appearance, 
probably the ten-thousandth part of an inch in 
diameter, to one-eighth of an inch, and are evi- 
dently disposed in different layers throughout the 
body of the pulp. They are of various shapes, as 
is shown at [PI. C. 6], Pulp Nos. 1 and 2. 
[No comparison can properly be instituted be- 
tween these vesicles and the cells of the ivory, for 
it is only at the surface of the pulp that these 
vesicles are prepared by some peculiar change in 
their form and arrangement for the reception of 
earthy matter.] 
When thin layers of macerated pulp are ex- 
amined, they present an irregular reticular appear- 
ance, and are found to be interspersed with 
granules. The parenchyma is traversed by vessels 
of which the direction is generally vertical, as seen 
in [PI. C. 7], Pulp No. 5. Pulp Nos. 3 and 4, 
[PI. C. 7], show the appearance of these cells in 
sections of the pulp which have been thus mace- 
rated. 
I have frequently been struck with the rapidity 20 
with which the pulp diminishes in volume, and 
with the extent of this diminution. Sometimes, 
indeed, it would appear in a short space of time to 
be almost annihilated, and this seems to take place 
more decidedly when the tooth has been in a 
healthy state, and more frequently in adult than 
in temporary teeth. This shrinking, or almost 
total disappearance, may, I think, be accounted 
for by a peculiar collapse or change in the con- 
geries of cells of which we find the pulp to be 
made up. The use of this peculiar arrangement, 
and the purpose which it serves in the economy of 
the part, will furnish curious subjects for future 
inquiry. A subject also highly worthy of inves- 
tigation is the nature of the contents of these cells. 
They must evidently be filled either with air or 
fluid, but they are so extremely minute that I have 
not yet been able to ascertain which. 
After repeated and careful investigation, I have 
convinced myself that they constantly exist on the 
surface of the pulp which is in apposition to the 
ivory, and which is essentially concerned in its 
developement. 
[By comparing, however, the diagram, Pulp 
No. 4, with Pulp No. 6 B, it will be seen that 
these vesicles are present on the surface of the 
pulp in a modified, more regular, and more dis- 
tinctly cellular form than in its interior ; and with 
this additional difference, that throughout the sub- 
stance of the pulp they present ill-defined layers, 
whereas, at its surface, they are arranged in reti- 
cular leaflets, to be hereafter described.] 21 
Much diversity of opinion has always existed 
respecting the connexion of the pulp with the 
ivory of the tooth ; and as to whether the ivory be 
simply a product of the pulp, or a transformation of 
its substance. Although this is by far the most 
interesting point in dental physiology, and involves 
the grand question of the manner in which the 
tooth is formed, as well as that of its arrangement 
and conformation, it is notwithstanding less under- 
stood, has been less studied, and is consequently 
more obscure, than any other part of the subject. 
The vague style in which authors discuss, or rather 
dismiss this topic, shows how little has been really 
done to elucidate it. I must confess that I devoted 
myself to its examination for a long time before I 
was fortunate enough to obtain any light where- 
with to guide my steps to the discovery of its true 
bearings, nor am I yet certain to what extent this 
knowledge of the structure of the transition surface 
of the pulp will be found to facilitate our compre- 
hension of the whole complicated process by which 
the ivory is developed.* 
* Although, from an examination of the diagrams, Pulp No. 
6 A. and No. 6 B., PI. C. 7, of all the diagrams in PI. C. 8, and 
of the first three in PI. C. 9, it is distinctly demonstrated that 
the interfibrous substance of the ivory is formed by the depo- 
sition of osseous matter in the cells of the reticular surface of 
the pulp, I cannot boast of being able fully to unveil that inter- 
esting process. The cells for the reception of the earthy 
matter are displayed, but—how is this matter arranged in those 
cells ? How is it, in the first place, derived from the blood and 
ntroduced into them ? What are the causes of the character- 
istic varieties of the interfibrous cellular substance in different 22 
The formative surface of the pulp displays a 
regular cellular arrangement, which I have deno- 
minated reticular, and which may be described as 
resembling a series of skeletons of desiccated leaves. 
(See [PI. C. 7], Pulp No. 6 A. and B.) It is not 
easy to obtain a preparation where the appearance 
is so perfect as to allow of a clear sketch of the 
consecutive parts of it being taken. The drawing 
I now present to your notice is the most perfect I 
have been able to obtain, and is from the tooth of 
a calf. The compartments of the reticulation are 
seen to be oval, and overlap one another. On in- 
sulating one of these compartments or leaves, (see 
[PI. C. 7], Pulp No. 6, B,) we find that its structure 
is curious and regular. These beautiful reticula- 
tions have peculiar diversities in different animals. 
I first observed them in the human pulp, and soon 
found them in all other animals which 1 had an op- 
portunity of examining, varying, as 1 have said, in 
size and arrangement in different cases. I next 
extended my observations to the capsule, and to the 
capsular investment of the enamel, and found in 
classes of animals? What is the precise degree of importance 
of the reticular cellular organization observed on the surface of 
the pulp with regard to the process of transition, besides the 
fact that it presents cells into which the earth is deposited ? 
Do these reticular cells form a system containing circulating 
fluids, from which the osseous material of the tooth is elimi- 
nated ? How are these cells connected together, both in their 
transition state and in the pulp, as well as when they have 
passed into the state of ivory ? These, and many other similar 
questions, remain to be solved before our comprehension of the 
process of the formation of ivory can be said to be complete. 23 
these the same reticular disposition, though with 
characteristic variations, as seen in diagrams marked 
“ Capsule” and “ Enamel Investment,” [One of 
these is seen at PL C. 11, No. 6,] 
These leaves of reticulation are surrounded by a 
well-defined scolloped border, from which occasion- 
ally processes are observed to project at regular 
intervals, (as may be seen at [PL C. 7] Pulp, No. 
6 B.) 
Having thus demonstrated the cellular texture of 
the pulp, throughout its entire extent, I next pro- 
ceeded to inquire how its transition into ivory is 
effected. The researches which I have made on 
this point are as yet imperfect, and I approach the 
subject with diffidence, knowing the deceptive re- 
sults to which novel experiments are liable; and 
well aware of the necessity of long study and de- 
liberation, before judgment be positively given on 
a point hitherto undecided. 
How does the fibre of the tooth originate ? and 
how is the interfibrous substance, which must form 
the main bulk of the tooth, deposited ? I will state 
how far my own observations allow me to answer 
these difficult questions. If I cannot at once satisfy 
the querist entirely on this subject, which has been 
seldom even approached, much less frankly entered 
upon, I may at least hope, by a few facts which I 
think my investigations have placed beyond doubt, 
to pave the way for a satisfactory explanation of the 
formation of dental bone. 
On the surface of the pulp are found innumerable 24 
detached cells, with central points. Generally, 
these cells form a regular and complete coating, 
studded with points, which are placed at intervals, 
corresponding in extent to those between the fibres. 
[PI. C. 8], Pulp, Nos. 10, 16, 12, and [PL C. 9] 
Nos. 13 and 14, show the appearances of these ossi- 
fied cells. 
These points are rendered visible from the greater 
opacity of the intermediate material, .and will be 
seen to reflect or absorb the light, according to the 
difference in the focal distance. A comparison 
between the superincumbent perfect ivory, and the 
formative surface of the pulp beneath, is always 
easy, because portions of the former, at an early 
stage at any rate, remain adherent to the latter, 
and fragments of the dental bone are found strewn 
over it, more especially in human teeth, as seen in 
the drawings alluded to above.* 
* It is almost unnecessary to state that it is impossible to 
obtain a clear view of the surface of the pulp after the process 
of the formation of ivory has commenced, without breaking 
away, or forcibly separating in some manner, the superin- 
cumbent crust of ivory from the pulp beneath; and in this dis- 
ruption the ivory is always somewhat shattered, and the surface 
of the pulp is found with separate cells and cellular fragments of 
all shapes, and in every stage of transition, strewn over it. In 
the diagrams marked Pulp No. 10, Pulp No. 16, Pulp No. 11, 
and Pulp No. 12 and No. 13, are seen fragments of this kind, 
coloured yellow. In No. 14, on the other hand, which is of 
a very young tooth, the pulp is shown at the period of the 
formation of the first layers of ivory; no disruption, conse- 
quently, was necessary in order to exhibit it, and hence the 
pulp is seen with its two superior layers in successive stages 
of transition into ivory. The fragments above alluded to can 25 
The cellular conformation of these fragments is 
always evident, and in size and appearance they 
never be too minute for the purposes of study. Indeed, there 
is no more satisfactory and interesting method of examining 
all hard organized bodies, than by pounding them in a mortar; 
fragments thus produced present themselves under an infinite 
variety of aspects, and display, in the most various and com- 
plete manner, the structure of these tissues. Such particles 
will never be too small for observation in the focus of the 
instruments of the present day. With respect to the pre- 
paration of anatomical specimens like the above-mentioned, 
where the formative surface of the pulp is shown by the re- 
moval of the ivory, I may observe that considerable patience 
and perseverance, and an abundant supply of subjects of in- 
vestigation, are indispensable before they can be properly made; 
and that even great proficiency and experience will not always 
insure success, which necessarily depends, to a certain extent, 
on fortuitous circumstances, such as the nature and state of the 
subject, the direction and degree of the fracture, &c. It some- 
times happens that out of a great number of fresh-drawn teeth, 
not one available preparation of this kind can be made. The 
pulp and the ivory being in positive union, the separation at the 
proper point seldom occurs. When, however, the industry of 
the inquirer is at length rewarded by a successful preparation, 
he will be gratified by a view of phenomena of the highest ge- 
neral physiological interest, the importance and full bearings of 
which could only be glanced at in the present memoir. 
It has been asserted that no preparations can be made from 
mammalia showing the transition of the pulp into ivory. Such 
a statement can only have originated in inexperience or in ill 
success, arising from causes hinted at above; but the number 
of such preparations of the most satisfactory kind which are in 
my possession, and which I am always glad to exhibit to any 
person who may feel a wish to see them, precludes the necessity 
for my wasting any of my own or my reader’s time, by refuting 
such an inconsiderate and groundless assertion. 26 
are perfectly accordant with the cells of the pulp. 
(See [PL C. 8] Pulp, 9 to 16, where the yellow 
colour shows the ossified cells or ivory.) 
At an early stage of dental developement, the re- 
ticulated or cellular appearance of the pulp is par- 
ticularly beautiful. When merely a thin layer of 
ossific matter has been deposited on its surface,* 
it may with great facility be drawn out entire, 
* I am ready to allow that there is a certain degree of 
vagueness in this phrase, which, had the paper been intended 
for publication, I should have rendered more definite and 
precise. It contains, however, not the slightest contradiction 
or incongruity; and it is only the most unfair and malevolent 
criticism which could avail itself of passages of this kind, 
written as they were for oral delivery, with the accompaniment 
of illustrative diagrams, and not for the press, to impugn the 
general tenor of my communications, written and graphic. 
“ The fact is,” as I have elsewhere observed, “ that when the 
“ external layer of the pulp becomes ossified, it can no longer be 
“ regarded as pulp. It is then spoken of as a layer of ivory in 
“ apposition to and connexion with the surface of the pulp be- 
“ neath. Thus the deposition of ossific matter on the surface of 
“ the pulp, simply means its deposition in the cells of the reticular 
“ formative surface, which is undergoing the process of dentifica- 
“ tion. That the idea of exudation could not even have been 
“ floating before my mind, is proved by a subsequent passage, 
“ where I state that the manner in which the osseous matter is 
“ deposited in the cells of the interfibrous substance I had not been 
“ able to discoverthe concluding portion of even the above 
paragraph proves the same: but it is useless to waste more time 
in demonstrating the monstrous absurdity of the assertion that 
my two papers on the structure of the teeth, and the diagrams 
exhibited in illustration of them, were in support of the theory 
of excretion or exudation ! 27 
together with the former, laid on a glass, compressed 
a little, and then examined with the high powers 
of the microscope. The different layers of cells 
will be seen, and the transition into ivory may be 
observed, (as shown in [PI, C. 9] Pulp No. 14, 
where the different gradations of ossification are 
marked by the shade of colour.) 
[The diagram marked Pulp, No. 6 A. [at 
plate C. 7] represents the general arrangement of 
the reticular leaflets of the surface of the pulp. In 
No. 6 B. is seen a beautifully-organized single 
leaflet of this reticular surface, in the pre-existing 
cells of which the earthy matter is in course of depo- 
sition, and the process of ossification is seen to be 
gradually extending from its centre towards its cir- 
cumference. No. 8 [plate C. 8] shows the blood-ves- 
sels coursing beneath the reticular formative sur- 
face. This drawing is an exact copy of the pre- 
paration, in which, as is seen, the blood-vessels 
have been ruptured in two places, in separating 
the ivory from the pulp, owing to the close con- 
nexion between the reticular surface and the ivory 
already formed. Pulp No. 9, with the title, Ossi- 
fication, or Developement of Ivory, and the following 
drawings, [see Plates C. 8 and 9,] are a selection 
from the interesting preparations which I have 
made for the purpose of elucidating the process of 
the formation of ivory. They display under vari- 
ous aspects the different appearances, some con- 
stant, the others incidental, which present them- 
selves on the removal of the superincumbent ivory 28 
from the surface of the pulp beneath. The portions 
coloured blue are cells of the pulp as yet unossified, 
and the parts coloured yellow are either entire lay- 
ers of ossified pulp-cells, or fragments of ivory which 
have remained adherent to the pulp, or extravasated 
fluid, containing probably osseous matter, (See 
[PL C. 8.] Nos. 11 and 12.) The whole appear- 
ances denote the existence of a peculiar system of 
cells external to the peripheral ramifications of the 
blood-vessels, the functions of which are highly 
interesting, and the study of which will ultimately 
lead, I think, to the unveiling of many vital pro- 
cesses connected with the growth of animal tissues, 
which are at present shrouded in obscurity, besides 
that which is rendered so clearly evident in the 
diagrams, marked [PI. C. 7] Pulp No. 6, B. ; [PI. 
C. 8] Pulp, Ossification, or Developement of ivory, 
Nos. 9, 10, 16, 11, 12 ; [PI. C. 9,j Pulp, Ossifica- 
tion or Devdopement of Ivory, Nos. 13 and 14, and 
which is plainly neither more nor less than a pro- 
cess of ossification ;—a view of it totally opposed to 
that which has been taken by previous inquirers 
into the formation of ivory.#] 
* To enter into a full description of the details of these 
drawings was impossible on an occasion like the meeting at 
Birmingham, and I was therefore compelled to trust in some 
measure to the ocular demonstration they alford for conveying 
to the audience an impression of the nature of the interesting 
process by which ivory is formed. Aware of the limited extent 
of time which could be granted me for the exposition of this 
complicated and comparatively uninvestigated subject, I, as far 
was possible, made it speak for itself in the drawings above 
mentioned. 29 
It appears to me that the framework of the reti- 
culation, or cells of the pulp, constitutes the fibres 
of the tooth, which, while in this state, are spirally 
coiled, and fit into one another. At all events, the 
diameter of these fibres of the reticulations is pre- 
cisely that of the fibres of the ivory; the points or 
projections rising from the framework correspond 
to the centres of the cells, and may be traced to 
belong to their structure. [The fibres composed of 
granules of animal matter, and which I describe as 
the framework of the reticulations, become, upon 
the deposition of ossific matter within the cellules 
of those reticulations, the fibres of the ivory. The 
only change which they appear to undergo during 
the process of transition, is, that they are then 
drawn out from the coiled-up state in which they 
exist between the collapsed cells of the reticulations 
into the more longitudinal but still spiral form in 
which they are found in the ivory. This will be 
fully understood by an examination of the dia- 
gram [PI. C. 9.] No. 15.] The fibres of the ivory 
are frequently very spirally curved, like those of 
the pulp, and as we should conclude they must be 
from the manner of their evolution, as seen in 
diagram, Ivory, No. 8.# Pulp No. 15, [PL C. 9], 
shows the appearances presented by a portion of a 
recent tooth, which has been submitted to the 
action of acid. Part of the pulp is visible in con- 
* This I cannot give in the present publication : it is of no 
essential importance. 30 
nexion with the ivory, and the spiral fibres are seen 
as they are evolved on the surface of the former. 
It appears to me, on microscopic examination, that 
this convoluted fibre is made up of single successive 
granules, which are developed one after the other 
from the body of the pulp, until the fibre is com- 
plete. I have, moreover, already shown that the 
fibre of decomposed teeth is resolved into separate 
granules or compartments, as is seen in the dia- 
grams marked “ Ivory deprived of Earth,” [PI. 
C. 6], Nos. 1 to 4. 
The manner in which the osseous matter is de- 
posited in the cells of the interfibrous substance, I 
have not been able to discover. It would appear, 
however, that these cells are subdivided into minute 
cellules, for they present the appearance of being 
filled with granules in certain progressive stages of 
developement, as is shown in diagrams [at PI. C. 8], 
Pulp Nos. 9, 10, 11, 12, [and C. 9], No. 13. 
In whatever aspect we view the formative organs 
of the tooth, and the dental tissues themselves, and 
whether we examine the latter during the process of 
their developement, or after their formation has been 
completed, we are everywhere met by appearances 
which denote a cellular or reticular arrangement. 
I must allow that these views of the formation 
and structure of the teeth are both bold and novel, 
but I do not claim for them infallibility; I simply 
submit them to the Association as the results of 
actual observation. I fully recognize and respect 
the authorities ranged in support of very different 31 
theories, though I still venture to think that, were 
not my limits confined, I could easily show how 
what I hold to be fallacies and incongruities have 
arisen. As, for instance, from want of practice in 
the manipulation of materials, the precise nature of 
which has not been attended to : want of familiarity 
with microscopic appearances; ocular deception; 
the want of a well-defined magnifying power, and 
imperfect light in the microscope used, have been 
doubtless, also, causes of many of the conflicting 
conclusions to which almost all inquiries in this 
region of anatomy have arrived. I think that the 
view I have taken of the subject more satisfactorily 
explains than any other, facts of daily experience. 
The laminated arrangement of the osseous cells 
explains the concentric fracture of the tusks of the 
mammoth, and of other teeth, when left to decom- 
pose spontaneously. The cells being in imbricated 
apposition, and held together by earthy salts, being 
moreover arranged in layers conformably with the 
periphery of the pulp, must be regarded as concen- 
trically laminated. The existence of this structure 
explains the phenomena daily noticed by ivory- 
cutters, and also Mr. Hunter’s experiments of 
feeding animals with madder, the result of which 
is incompatible with any other theory of the struc- 
ture of dental bone. 
No view hitherto taken of the structure of dental 
bone has afforded a satisfactory explanation of the 
ordinary morbid appearances of the tooth, but 
many of these I think may be explained, if we 32 
regard the latter as cellular. Still I do not con- 
ceive that I have in any way exhausted the subject; 
far from it; I am quite alive to the imperfect nature 
of my researches, and am prepared for cor- 
rection on many points, when more extended 
and varied investigations shall have been under- 
taken. 
I find that Schwann, in a recent work, teaches 
that all the primary tissues of the animal frame are 
cellular, and has given to the world some remark- 
ably interesting details on this subject. He says 
that he has remarked the characteristic “ cellular 
nuclei,” or elementary cells, on the enamel-mem- 
brane, that they are continued in minute fibres, 
and that these are similar to the epithelium cylin- 
ders in mucous membranes. He notices what he 
calls cylindrical cells on the surface of the pulp, 
and he supposes that these cylindrical cells of the 
pulp are the fibres of the tooth in their first stage, 
which does not at all coincide with my observa- 
tions. He regards the dental substance simply 
as the ossified pulp, whilst my observations lead 
me to conclude that the cells of the ivory are alto- 
ther a distinct formation.* He acknowledges, 
* To show the unwarrantable means which have been had 
recourse to in order to misrepresent my views of the formation 
of ivory, I beg to quote from an article in the Medical Gazette 
the following passage, exposing the manner in which the above 
statement has been tampered with and misrepresented : 
“ At p. 507, of the last week’s number of this journal, he (Mr. 
Owen) manufactures what he is pleased to call Mr. Nasmyth’s 33 
however, that he is ignorant of the process of tran- 
sition, and he regards the dental pulp as a simple 
cartilage. In fact, he starts with a ready-made 
hypothesis, and founds his opinion rather on the 
observations of others, and on the inferences he 
draws from them, than on his own actual re- 
searches : with respect to what he himself gives as 
his own, it accords for the most part with the 
details I have just communicated. 
The following is the account contained in his 
work on the structure and function of the pulp. 
“ According to Purkinje and Raschkow, the 
pulp consists at first of nearly uniform globules, 
without vessels and nerves; afterwards, vessels 
emphatic statement of September 1839, ‘that so far from being 
the ossified pulp, it (the dental substance) was altogether a dis- 
tinct formation.’ Now of this passage, which he gives as 
quoted from the Literary Gazette, p. 598, only the four last 
words will be found, on reference to that journal,” (and to the ori- 
ginal paragraph itself in the paper above,) “ to be correctly 
copied : all the first part of the passage is the composition of Mr. 
Owen. Mr. Nasmyth, by this perversion of his report, is made 
to say that the dental substance is altogether a distinct forma- 
tion : whereas he never mentions the dental substance at all, 
and his real meaning evidently is, as we have shown above 
that the cells of the ivory have undergone a distinct formative 
process in their transition from the cells of the pulp. Such 
unfair and unworthy tactics must inevitably defeat the purpose 
for which they were adopted. Mr. Owen’s unscrupulous vio- 
lence, far from concealing, as he seems to calculate it may do, 
the weakness of his arguments, will only still further damage 
his cause, in the eyes of every dispassionate reader.”—Medical 
Gazette for July 3, 1840. 34 
arise in it, and at last nerves also. On the surface 
the globules are more regularly arranged, and 
more longitudinally extended, and turned in an 
external direction under right or slightly acute 
angles. 
“ These longitudinally drawn out globules are 
plainly cylindrical cells. They contain very evidently 
in recent (fresh) teeth the characteristic cellular 
nucleus with its nucleus-corpuscles, and are very 
sirftilar to the prisms of the enamel membrane. The 
interior of the pulp consists of round cells, also with 
a nucleus, and between these cells run vessels and 
nerves. If we draw the pulp of a young tooth out 
of its cavity, and then examine the dental sub- 
stance, whether deprived or not of its calcareous 
salts by muriatic acid, we shall find on its internal 
surface, at any rate inferiorly, where the already 
formed dental substance is still thin and soft,a layer 
of the cylindrical cells of the pulp. These have 
about the same thickness as the solid fibres of the 
dental substance, and also the same course; and 
inasmuch as they, on the one hand, plainly belong 
to the pulp, on account of their conformity with 
the cylindrical cells adhering to the remaining 
surface of the pulp, and, on the other hand, as 
they cohere more firmly with the dental substance 
than with the pulp, and remain attached to the 
former, I presume that here a transition takes 
place, and that the cylindric cells of the pulp are 
only the fibres of the tooth in their first stage, and 
change into the latter by filling with organic 35 
substance, becoming solid and ossifying’. Some- 
times these cylindrical! are not found on the dental 
substance, but then in their place are found a 
number of cellular nuclei. These are of a very 
pale colour, and are intimately connected with the 
dental substance, so that they are easily over- 
looked ; but when the attention is once directed 
to them, it is impossible not to recognize them : 
the spaces between them are very narrow. Against 
the theory that the dental substance is the ossified 
portion of the pulp, the facility with which the one 
is separated from the other has been adduced ; and 
I allow the force of this objection. Nevertheless 
it is at any rate weakened by the circumstance that 
a portion of the pulp actually remains attached to 
the dental substance, and by the fact that in half 
ossified ribs, for instance, the cartilage can be 
easily separated from the ossified portion, and it 
must be remembered that in the tooth the separa- 
tion must be easy in proportion to the difference 
between the consistence of the pulp and of the 
dental bone.”* 
* I consider it a duty to acknowledge with gratitude the 
obligation I am under to the editor of the Literary Gazette for 
the extended report of my communications which he inserted 
in his excellent journal. hen I placed in that gentleman s 
hands a rough draft of my papers to assist him in oraw- 
ing up his report of them, I did not expect that he would 
have given me the benefit of so extensive a report as that 
which made its appearance. 1 was not able, however, to see a 
proof of it, or I should certainly have endeavoured to explain 
more fully the allusions to the diagrams, and to introduce a few 
D 2 36 
of the oral observations in explanation of the latter, without 
which it is possible that some portions of the paper, referring as 
they do exclusively to the diagrams, may appear rather incom- 
plete. An omission which was made in the Literary Gazette 
with respect to my account of Schwann’s researches, has given 
rise to some ridiculous observations. The mistake consisted in 
the editor’s omitting in his report the sentence immediately 
preceding my account of Schwann’s researches. 37 
MEMOIR No. III. 
Investigations into the Structure of the Epithelium, 
presented to the Medical Section of the British 
Association for the Encouragement of Science, at 
its Meeting held at Birmingham in August, 1839. 
By Alexander Nasmyth, M.R.C.B., &c. &c. 
In a former part of this communication I have 
endeavoured to prove that the pulp, the formative 
organ of the tooth, is composed of cells. I have 
also shown, that the character of the teeth them- 
selves is more or less cellular ; and the observations 
which I have made on the structure of the epithe- 
lium have led me to a conviction, that it also is 
composed of cells. Although some of the facts 
which I am about to relate, have, since the prosecu- 
tion of my researches, been noticed by Henle and 
Schwann in Germany, I think it right, neverthe- 38 
less, to state concisely all the results of my investi- 
gations. 
Leeuwenhoek, who did so much towards the ad- 
vancement of structural anatomy, was the first to 
give an accurate account of the structure of the 
epithelium. His researches on this subject are con- 
tained in letters to the Royal Society in the years 
1674, 1684-85, which will be found in the third 
and fourth volumes of his collected works. He 
there states, that the human epidermis and epithe- 
lium are composed of scales, and of these he has 
left very accurate descriptions and delineations. 
He spoke of the scales of the epithelium as existing' 
upon the mucous membrane of the mouth. The 
researches of subsequent observers tend to prove 
that these scales or cells exist in various forms upon 
the surface of all mucous and serous membranes, 
upon the inner membrane of the vascular system, 
&c. With respect to the existence of these scales on 
almost all these membranes, I agree with the autho- 
rities whom I have just quoted; and having pre- 
mised thus much, I shall now proceed to treat, 
firstly, of the structure of the epithelium generally ; 
and, secondly, of the epithelium as existing in the 
cavity of the mouth. 
Structure of the Epithelium generally. — The 
epithelium is a layer of substance destitute of 
vessels, which covers the vascular surface of mu- 
cous membranes. Though destitute of vessels, it 
cannot, however, be considered as inorganic, as I 
shall presently show. If the surface of a mucous 39 
membrane (for instance, the conjunctiva or the 
buccal) of a living animal be slightly rubbed, it 
will be found, on microscopic examination, ‘that 
numerous small particles have been detached from it. 
At the first glance they present precisely the ap- 
pearance of scales, for they are flat bodies with a 
thick portion or nucleus in their centre, and with 
very thin and transparent margins. It was Leeu- 
wenhoek who first gave to these bodies the name 
of scales. They are found not unfrequently with 
a curved margin and without a central spot or 
nucleus, and their surface often presents numer- 
ous transparent points, with very fine lines. The 
nucleus of the scale generally contains a small 
body which has been termed the nucleus-corpus- 
cle. But by this simple method of observa- 
tion we do not obtain an insight into their true 
structure. If we remove the secretion from the 
surface of an irritated mucous membrane, we shall 
find another class of bodies which differ from these 
first mentioned, in being smaller and more globular. 
They have a nucleus of the same size as those of 
the so-called scales, and also a nucleus-corpuscle, 
but the surrounding structure is in the form of a cell, 
and is much smaller. Here and there may also 
be observed a nucleus with its accompanying cor- 
puscle, lying in substance which presents no ap- 
pearance of a cell. The structures here described 
may also be seen on a careful examination oi 
a section of the epithelium and mucous mem- 
brane of a young subject. On the surface of, and 40 
in immediate apposition to, the mucous membrane, 
are seen numerous nuclei, which more externally 
are surrounded by a cell; and on approaching still 
nearer to the surface, we find this cell, from having 
increased considerably in size, and become com- 
pressed, assuming the appearance of a scale, which 
retains the nucleus, and its corpuscle of primitive 
size. The various stages of the developement of 
the epithelium may be satisfactorily traced, by re- 
moving, after a short maceration, the layer of epi- 
thelium from the under surface of the tongue of a 
young calf, and placing it upon a piece of glass, 
when, if the external surface of the object be 
brought into focal distance, large scales only with 
their central nuclei are observable ; but if the ob- 
ject be approximated to the glass so as to bring the 
internal part of it into the proper focal distance, 
numerous small scales are brought into view; and 
if the object be still more approximated to the lens, 
so as to bring its internal surface into the proper 
focal distance, numerous rounded cells become ap- 
parent. 
In the foetus, the defined and well-formed scales 
of the epidermis are not unfrequently distinctly 
seen externally ; the rete Malpighii consists of 
newly-formed cells, and between the two may be 
observed other cells in a state of progressive deve- 
lopement. On the surface of the vascular mucous 
membrane minute cells are found with a nucleus in 
their interior, round which the cells grow ; and this, 
in short, is the process of developement of the mi- 41 
nute bodies which constitute the epithelium. An 
interesting subject of investigation, and one which 
I believe has not been entered upon by those who 
have hitherto treated of this department of anato- 
mical science, is the manner in which the compo- 
nent parts of the epithelium are connected. The 
cells on the surface of the mucous membrane are 
separated from each other by considerable spaces, 
which are occupied by a gelatinous substance, in- 
terspersed with minute granular bodies. But the 
scales forming superficial layers of the epithelium 
are separated by very minute linear spaces, but are 
still connected together by a translucent, gelatinous 
substance. 
This latter displays considerable elasticity, as is 
easily rendered evident by an attempt to lacerate 
the epithelium in a moist state, if the latter be ex- 
amined at the same time by the aid of a mag- 
nifying power. Each time that the laceration is 
attempted, the membrane yields, and the scales 
separate to a certain extent; but regain their ori- 
ginal position, on the cessation of the effort to draw 
them apart. In some instances a fibrous structure 
is evident in the gelatinous substance between the 
scales, See Diagram, No. 3. (PI. C. 10.) 
The scales towards the free surface are distinctly 
observed to overlap. The gelatinous substance 
above alluded to, presents distinct granular bodies, 
which give to the epithelium, en masse, a rather 
dense aspect, the individual scales being sometimes 
covered by these granules; the latter can, however, 42 
be separated from the scales by compression; by 
which means, indeed, the granules themselves may be 
made entirely to disappear. In certain parts of the 
epithelium of the calf, distinct fibres are observed, 
which pass over the surface of the scales, and con- 
nect them together, thus forming a very delicate 
net-work. This appearance is most evident upon 
compression of the thick epithelium on the anterior 
part of the alveolar arch of the upper jaw. 
In these cases, where the small scales, or small 
clusters of scales, are being continually thrown off, 
as on the surface of the body, and of the mucous 
membranes of man and animals generally, the 
scales composing the external layer will be found 
to overlap each other, and thus the gradual pres- 
sure of scales below, which are increasing in size, 
is the cause of the throwing off of these cuticular 
lamellae. After these have been detached, their 
place is occupied by newly-formed scales. But 
there is another form in which the external layer 
of cuticle is removed, viz. in a continuous layer. 
The cuticle of the frog is composed of minute scales, 
the borders of which do not overlap, but are held 
in direct apposition, so as to form one lamina, 
which has a beautiful continuous tesselated appear- 
ance. This layer, of which I here display consi- 
derable portions covering the whole body, is thrown 
off* entire by frogs and efts; and I am disposed 
to believe that it is this covering which, according 
to naturalists, is swallowed by the animal after 
having been thrown off*. As soon as this layer is 43 
removed, another lamina of scales is seen on the 
surface of the animal’s skin. If after the death of 
a frog it be immersed in water, this thin external 
translucent layer generally separates; but upon 
prolonging the maceration, another lamina is found 
to be gradually separating from the cutis, which is 
dense, and sometimes measures a quarter of a line 
in thickness. Internally it will be found to be com- 
posed of very numerous cells, while externally the 
regular series of scales is evident. The tesselated 
lamina alluded to above evidently takes its origin 
from this layer of cuticle. An examination of the 
specimens which I here present to your notice, and 
a consideration of the facts which I have related, 
cannot, I think, lead to any other conclusion than 
that the cuticle and epithelium are organised tis- 
sues. It would appear that they are formed from a 
fluid secretion on the surface of the vascular corion. 
The various stages of developement being, 1, the 
formation of nuclei and corpuscles; 2, that of 
cells ; 3, the growth of the latter effected by vital 
imbibition ; 4, their compression and gradual 
conversion into minute lamellae or scales. [See 
PL C. 10. Nos. 2 and 3.] In short, it appears 
a rational conclusion that the component parts of 
the cuticle and epithelium have within them- 
selves a power of growth; and it remains for 
pathologists to determine what share the derange- 
ment of this function has in the production of 
cutaneous diseases. Another argument in favour 
of the organic nature of the epithelium is derived 44 
from the circumstance, that under certain modifi- 
cations it presents various vital phenomena, among 
which may be mentioned the ciliary motions. 
I now proceed to describe my researches on the 
structure and developement o£ that portion of the 
epithelium which lines the cavity of the mouth. 
In the foetal subject, previous to the extrusion of 
the teeth, it forms on the alveolar arch a dense, 
projecting layer, distinguishable from the sur- 
rounding membrane by its whiteness, and by the 
existence on its surface of ridges and sulci, having 
a waving course and a variable direction. The 
alveolar epithelium is thicker in proportion to the 
youth of the subject examined. It is most promi- 
nent where it corresponds with the molar teeth : 
its internal surface is concave, receiving the pro- 
jecting mucous membrane. This portion presents 
various objects for investigation. 
Firstly, as regards its composition :—It is made 
up of a mass of scales, lying one on the surface of 
the other. This disposition shows that the terms 
“ dental cartilage/’ or the “ cartilage of the gum,” 
which have hitherto been applied to this structure, 
give an erroneous idea of its true nature, for car- 
tilage always presents the corpuscle discovered 
and described by Purkinje. As in other portions 
of the epithelium, the external scales here are the 
larger, and this holds good generally, until we 
come to the surface of the vascular mucous mem- 
brane, which presents simple cells with their cor- 
puscles. 45 
In the interior of this alveolar epithelium, where 
it corresponds to the molar teeth, small vesicles 
may be frequently observed, varying in size from 
one quarter to one-eighth of a line in diameter. 
They appear to the naked eye to be transparent; 
under the microscope their parietes are found to 
consist of attenuated scales, and their cavity to 
contain a fluid abounding in minute granules and 
cells.* The internal surface of the epithelium 
covering the alveolar arch frequently presents con- 
cavities or indentations which are from a line and 
a half to three or four lines in circumference : they 
correspond to projections from the mucous mem- 
brane formed by a larger species of vesicle. The 
latter is deeply implanted in the vascular mucous 
membrane. The parietes of these vesicles are 
composed of a very delicate membrane ; they con- 
tain a transparent fluid which coagulates on the 
application of heat, or acid, or on immersion in 
spirit, and in this fluid float numerous globules 
and scales similar to those of the epithelium gene- 
rally. The internal or attached surface of the 
alveolar epithelium also presents numerous fringed 
processes measuring from one line to one and a 
half lines in length, and half a line in breadth, 
which sink into the substance of the subjacent 
mucous membrane. Under the microscope these 
* The vesicles here alluded to are most probably those which 
Serres describes as glands for the secretion of tartar: they are 
very numerous even after the extrusion of the incisor teeth of 
the calf, and are seen with great facility internally. 46 
fringes are found to be composed of elongated 
scales connected together, forming masses which 
divide and subdivide until they attain such an ex- 
treme tenuity that the most minute terminations 
consist but of two scales in marginal apposition. 
If the epithelium be carefully separated from the 
surface of the mucous membrane corresponding 
to the unextruded molar teeth, and placed in water 
or in diluted spirit of wine for some little time, 
its internal or attached surface presents these 
fringes much enlarged and forming a mass more 
considerable in size than the dense epithelium 
itself. 
The epithelium covering the mucous membrane 
of the palate presents transverse rugae, correspond- 
ing to those of the mucous membrane. If these 
palatal rugae of the epithelium of the calf be care- 
fully examined from the internal surface with a 
magnifying power of one inch focal distance, each 
will be found to consist, or to be composed of, 
numerous depressions or cul de sacs which receive 
prolongations or pointed processes of the subjacent 
mucous membrane. 
They are of extreme tenuity, and, wThen viewed 
by the aid of high magnifying powers, are observed 
to consist of distinct scales. 
A question of much interest, and one to which 
I have paid considerable attention, is whether 
recent investigators are warranted in considering 
mucus and epithelium as identical; I am disposed 
to think that they are formations quite inde- 47 
pendent of each other; but my reasons for arriving 
at this conclusion are numerous, and the details of 
my investigations upon this part of the subject 
I propose to treat of at length elsewhere. 
LONDON: 
PRINTED BY G J. PALMER, SAVOY STREET, STRAND.