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te. Ho Leta

HORSES’ TEETH:

A TREATISE ON THEIR

MODE OF DEVELOPMENT, ANATOMY,
MICROSCOPY, PATHOLOGY, AND DENTISTRY ; COMPARED WITH
THE TEETH OF MANY OTHER LAND AND MARINE
ANIMALS, BOTH LIVING AND EXTINCT;

WITH A VOCABULARY AND COPI-

CUS EXTRACTS FROM
THE WORKS OF

ODONTOLOGISTS AND VETERINARIANS.

| mob \ BY y

(2 WILLIAM H. CLARKE.

* Ta Pe

\
ad
a

Zz “
(Ss ( SECOND @BDITION, REVISED.
\ . VA
a ae > :
Rae ht 8 NM A

i, 4 |
’ 4 \ L
—
SS as

Horses have very nearly the same diseases as men.— Pliny.
We ought to make not merely books, but valuable collections, and to

ackuowledge the sources whence we derive assistance.—Zdid.
— a 7 -
va oT: aR
“TRIGH, &o

Qa

‘NEW YORK: \ OCT_13 1899 °

WILLIAM R. JENKINS, \. 3666 8

SS ASHINGT
VETERINARY PUBLISHER AND BOOKSELLER,

. 850 Sixru AVENUE. oe
1884.

Copyright, 1879, by

Suirn & McDoveat, Execrroryrers,

82 Beekman St., N. Y.

OO ear

PREFACH.

HE favorable reception of the first edition of this
work by both press and public and my desire
to encourage the study of Veterinary Science and
Comparative Anatomy are the chief reasons for a
Revised Edition. 'The improvements consist in an
Appendix, numerous Illustrations, a new Index, and
the correction of errors in and the addition of fresh
matter to the text and vocabulary.

I am indebted to Mr. Jacob L. Wortman of Phil-
adelphia for the able article on fossil horses in the
Appendix, and to Prof. E. D. Cope, editor of The
American Naturalist, for a careful revision and im-
provement of it. Some of the reference notes, how-
ever, are my own.

It was not my intention originally to make the book
an exponent of the Doctrine of Evolution. The dis-
cussion of the subject, however, is justifiable, for a
work that does not embrace all the facts science
furnishes is unworthy of the age, and to shirk the re-
sponsibility of the discussion because the subject is

unpopular is cowardly. The fact. that fossil horses’

teeth are inseparably connected with those of the
modern horse renders their consideration unavoidable.
Further, in addition to being one of the most impor-
tant factors Paleontology has thus far furnished in

iv PREFACE.

elucidating the subject of Evolution, they give in-
creased scope and importance to the book itself.
Truly the late Dr. John W. Draper was right when,
at a mere glance, he said: ‘‘The subject (horses’
teeth) is so suggestive !”

So far as Evolution is concerned, I can only repeat
what I said in the first Preface, namely, that it denotes
improvement, and that Nature’s laws are immutable,
and to oppose them is as foolish as to beat the head
against a stone wall.

Again, as said in the first Preface, I think I can say
now from experience that Special Works, on account
of the thoroughness with which they are usually pre-
pared, are growing in public favor (an opinion in
which so able a journal as The Syracuse (N. Y.)
Standard concurs), and that while General Works
have their advantages, thoroughness of detail is not
usually among them.

W. i C.
NEw YORK, September, 1883.

CONTENTS.

INTRODUCTION.—Fundamental Principles of Dental Science........

CHAPTER I.

TOOTH-GERMS (ODONTOGENY).

Periods at which the Germs are visible in the Fetus.—Dentine and
Enamel Germs.—A Cement Germ in the Foal.—The Horse’s Upper
Grinders said to be developed from Five Germs, the Lower from
Four.—Similar development of the Human Teeth.—Monsieur Mag-
St SRL OII GS ay oso eo owns can vetdvre tev inee Wee tReet eet

CHAPTER II.

THE TEMPORARY DENTITION.

Twelve Incisors and Twelve Molars.—Why the Incisors are calle
‘“ Nippers.”"—The Treatment of Foals Afiects Teething.—Roots
of Milk Teeth Absorbed by the Permanent.—The Tushes..........

CHAPTER III.

THE PERMANENT DENTITION.

Distinction between Premolars and Molars._The Bow-like Incisors.—
Contrasts between the Upper and Lower Grinders, and the Rows
formed by them.—The Incisors saved from Friction.—forses’
Teeth compared with those of other Animals.—Measurements.—
Time’s Changes.—Growth during Life...... sea Sree aromeiticinte acto wae ae

CHAPTER IV.

THE CANINE TEETH OR TUSHES.

Practically Useless.—-Different in their Nature from the other Teeth.—
Were they formerly Weapons of Offense and Defense i!—Views of
Messrs. Darwin. Hunter. Bell, Youatt, and Winter.—Their time of
Cutting the most Critical Period of the Horse's GilG. vex sis cents

CHAPTER V.
THE REMNANT TEETH.

Usually regarded as Phenomenons.—The Name.—Traced to the Fossil
Horses, in which (in the Pliocene Period) they ‘‘ Ceased to be Fune-
tionaliy Developed.”—Nature’s Metamorphoses —‘‘ The Agencies
which are at work in Modeling Animal and Vegetable Forms.”—
Why Remnaft Teeth are often as it were, Prematurely Lost.—Fos-
sil Horses and a Fossil Toothed-Bird......... 2 ............ ine eae

31

47

53

7%

vl CONTENTS,

CHAPTER VI.

DENTAL CYSTS AND SUPERNUMERARY TEETH. PAGE

Teeth growing in various parts of the Body.—Some Cysts more Prolific
than others, Producing a Second, if not a Third, ‘‘ Dentition.”—
Reports and Theories of Scientific Men.—Cases of Third Dentition
TN VEPMIMAN EIN O Us Ls aiorts.o csiee e's tenis oa diac sce vlnla'es'¥-e/0: eevee re eae 115

CHAPTER VIL.

HORSES’ TEETH UNDER THE MICROSCOPE.

The Dentinal Tubes, Enamel Fibers, and Cemental Canals Described
and “COmtrasted Foch). Ss ciccewalessistocs Boece Speten wieioigs «6 sie. Wastes 130

CHAPTER VIII.

THE PATHOLOGY OF THE TEETH.

Importance of the Subject.—Caries caused by Infiamed Pulps, Blows,
Virus, and Morbid Diathesis.—Supernumerary Teeth and other
Derangements.—Trephining the Sinuses.— Gutta Percha asa Fill-
ing.—Cleaning the Teeth.— A Diseased Fossil Tooth............-«. 136

CHAPTER EX.

THE DENTISTRY OF THE TEETH.

Reports of Cases Treated by Various Surgeons.—Gutta Percha as a
Filling for Trephined Sinuses.—Teeth Pressing against the Palate.
—Passing a Probe through a Decayed Tooth.—Death of a Horse
from Swallowing a Diseased: Tooth. ........00sacacccceceescnse ome 175

CHAPTER X.

FRACTURED JAWS.

How Caused, and how to Distinguish an Abrasion of the Gums from a
Fracture of the Bone.—Replacing an Eve, Amputating part of a
Lower Jaw, taking a Fractured Tooth and Bones out through the
Wostrtl, Que... ito es te ccm ce ea kaesd ape sparen ae aie en eee 194

CHAPTER XI.

THE TEETH AS INDICATORS OF AGE.

Their various ways of Indicating Age.—The ‘‘ Mark’s” Twofold Use.—
The Dentinal Star.—Marks with too much Cement.—Tricks of the
Trade.— Crib-biting.—Signs of Age Independent of the Teeth...... 203

CHAPTER XII.

THE TRIGEMINUS OR FIFTH PAIR OF NERVES.

Its Nature and the Relation it bears to the Teeth.—Its Course in the
Hiorse: arid) baa Maga eo os ch So bee's Set or atarene wei ol welt atet ole lelars) etal otts ale nan eeapatele 216

WOCABULA RY, - Fr cncme kan zts Fave) acai opehafonete, qlatuus tors = pe vo eYatel = ea\arsiet telnet 227

APPENDIX.—Recent Discoveries of Fossil Horses.—Views of an Evo-
lutionist.—Original Home of the Horse.—Elephant Tooth-Germs.—

Filling Children’s Teeth. . 0.0... is oan sen 00 craic eee nos sein shvin sis igi eaininie 257
DINE ss, at citostic kins ile 06s ors moe hiapeieen ed eaioin ears of Ge sic niteaataereneae 279
PU DEES OP TNGOR «ir oose 'sst, Hoe an lel Pa ore od Seam snuda ate eer Pe |

INTRODUCTION,

THE following matter, which is designed to give at
least a synopsis of the fundamental princivles of dental
science, is compiled from the works of the best known
odontologists. It is somewhat heterogeneous in its
make-up, and is, moreover, considering that it is an
Introduction to a special work, anomalous, being
rather an adjunct to than an explanation of the work
itself. Its lack of coherency and the few repetitions,
the inevitable concomitants of all compilations, are
offset by the interest of its historical records and the
scope and clearness of its thoughts and deductions.
While it does not treat specially of horses’ teeth, it is
just as applicable to them as to human teeth, or to
those of any of the other animals mentioned. It is
believed that the student of dental science will find
_ the matter as useful as it is interesting.

In his work entitled “The Anatomy of Vertebrates”
(vol. i, pp. 357-8), Prof. Richard Owen says:

“A tooth is a hard body attached to the mouth or
beginning of the alimentary canal, partially exposed,
when developed. Calcified teeth are peculiar to the
vertebrates, and may be defined as bodies primarily, if
not permanently, distinct from the skeleton, consisting

vili INTRODUCTION.

of acellular and tubular basis of animal matter, con-
taining earthy particles, a fluid, and a vascular pulp.

‘In general, the earth is present in such quantity
as to render the tooth harder than bone, in which case
the animal basis is gelatinous, as in other hard parts
where a great proportion of earth is combined with
animal matter. In a very few instances, among the
vertebrate animals, the hardening material exists in a
much smaller proportion, and the animal basis is albu-
minous; the teeth here agree, in both chemical and
physical qualities, with bone.

**T propose to call the substance which forms the
main part of all teeth dentine.* The second tissue,
which is the most exterior in situation, is the cement.
The third tissue, which, when present, is situated be-
tween the dentine and cement, is the enamel.

“ Dentine consists of an organized animal basis and
of earthy particles. ‘The basis is disposed in the form

*In a reference note in the Introduction to his “‘Odontogra-
phy,” Prof. Owen says: “Besides the advantage of a substan-
tive for an unquestionably distinct tissue under al] its modifica-
tions in the animal kingdom, the term dentine may be inflected
adjectively, and the properties of this tissue described without
the necessity of periphrasis. Thus we may speak of the ‘ denti-
nal’ pulp, ‘dentinal’ tubes or cells, as distinct from the corre-
sponding properties of the other constituents of a tooth. The
term ‘dental’ will retain its ordinary sense, as relating to the
entire tooth or system of teeth.”

Note.— The particular paragraph to which the above note re-
fers is from Prof. Owen’s ‘“‘ Odontography.” ‘‘ The Anatomy of
Vertebrates ” having been written about twenty-five years sub-
sequent to the *‘Odontoeranhy,” and therefore reflecting the
Professor’s riper thoughts, the extracts made from it were sub-
stituted for very similar matter in the “ Odontography.”

TUBES WITH NOURISHING, COLORLESS FLUID. ix

of compartments or cells, and extremely minute tubes.
The earthy particles have a twofold arrangement, be-
ing either blended with the animal matter of the in-
terspaces and parietes of the tubes, or contained in a
minute granular state in their cavities. The density
of the dentine arises principally from the proportion
of earth in the first of these states of combination.
The tubes contain, near the formative pulp, filament-
ary processes of that part, and convey a colorless fluid,
prebably transuded ‘plasma.’ They thus relate not
only to the mechanical conditions of the tooth, but to
the vitality and nutrition of the dentine. This tissue
has few or no canals large enough to admit capillary
vessels with the red particles of blood, and it has been
therefore called ‘unvascular dentine.’

“ Cement always closely corresponds in texture with
the osseous tissue of the same animal; and whenever
it occurs of different thickness, as upon the teeth of
the horse, sloth, or ruminant, it is also traversed, like
bone, by vascular canals. When the osseous tissue is
excavated, as in dentigerous vertebrates above fishes,
by minute radiated cells, forming, with their contents,
the ‘corpuscles of Purkinjé,’ these are likewise present,
of similar size and form, in the cement, and are its
chief characteristic as a constituent of the tooth. The
hardening material of the cement is partly segregated
and combined with the parietes of the radiated cells
and canals, and is partly contained in disgregated
granules in the cells, which are thus rendered white
and opaque, viewed by reflected light. The relative
density of the dentine and cement varies according to
the proportion of the earthy material, and chiefly of
that part which is combined with the animal matter
in the walls of the cavities, as compared with the size

x INTRODUCTION.

and number of the cavities themselves. In the complex
grinders of the elephant, the masked boar, and the
copybara, the cement, which forms nearly half the
niass of the tooth, wears down sooner than the dentine.
“‘The enamel is the hardest constituent of a tooth,
and, consequently, the hardest of animal tissues; but
it consists, like the other denial substances, of earthy
matter arranged by organie forees in an animal matrix.
Here, however, the earth is mainly contained in the
canals of the anima! membrane, and, in mammals and
reptiles, completely fills those canals, which are com-
paratively wide, whilst their parietes are of extreme
tenuity. The hardening salts of the enamel are not
only present in far greater proportion than in the den-
tine and cement, but, in some animals, are peculiarly
distinguished by the presence of the fluate of lime.”

Again Prof. Owen says (‘ Anat. of Vert.” vol. i, pp.
359-60) :

‘Teeth vary in number, size, form, structure, modi-
fications of tissue, position, and mode of attachment
in different animals. They are principally adapted for
seizing, tearing, dividing, pounding, or grinding the
food. In some animals they are modified to serve as
weapons of offense and defense; in others, as aids in
locomotion, means of anchorage, instruments for up-
rooting or cutting down trees, or for transport and
working of building materials. They are characteristic
of age and sex, and in man they have secondary rela-
tions subservient to beauty and to speech.

“Teeth are always most intimately related to the
food and habits of the animal, and are therefore highly

{OST DURABLE OF ANIMAL SUBSTANCES, x]

interesting to the physiologist. They form for the
same reason most.important guides for the naturalist
in the classification of animals; and their value, ag
zoological characters, is enhanced by the facility with
which, from their position, they can be examined in
living or recent animals. The durability of their tis-
- sues renders them not less available to the paleontolo-
gist in the determination of the nature and affinities
of extinct species, of whose organization they are often
the sole remains discoverable in the deposits of former
periods of the earth’s history.”

Prof. A. Chauveau says (“Comparative Anatomy of
the Domesticated Animals”):

“Identical in all our domesticated animals by their
general disposition, mode of development, and struc-
ture, in their external conformation the teeth present
notable differences, the study of which offers the
greatest interest to the naturalist. For it is on the
form of its teeth that an animal depends for its mode
of alimentation; it is the régime, in its turn, which
dominates the instincts, and commands the diverse
modifications in the apparatus of the economy; and
there results from this law of harmony so striking a
correlation between the arrangement of the teeth and
the conformation of the other organs, that an anato-
mist may truly say, ‘Give me the tooth of an animal,
and I will tell you its habits and structure.’”

In a letter which I wrote to Prof. Theodore Gill, of
the Smithsonian Institution, Washington, D. C., I
asked what there was about teeth that enabled natu-
ralists to tell so much by them. In reply he said:

Xi INTRODUCTION.

“The teeth are quite constant in the same type, are
generally appreciably modified according to family, are
the most readily preserved in a fossil state, and are in
direct relation with the economy of the animal. Hence
they furnish the best indications of the relations of
the animal-to which they belonged, especially in cases
where the type was not very different from an existing *
one. In the case of the older and more aberrant types,
however, the indications furnished by the dentition
should be accepted with great caution.”

In the Introduction to his “ Odontography ” Prof.
Owen gives, besides his own and other men’s views, a
history “of the leading steps to the present knowl-
edge” of dental science (that is, up to 1844), of which
the following are extracts:

“ As regards the teeth, the principle of chief import
to the physiologist arises out of the fact, which has
been established by microscopic investigations, that the
earthy particles of dentine are not confusedly blended
with the animal basis, and the substance arranged in
superimposed layers, but that these particles are built
up with the animal basis as a cement, in the form of
tubes or hollow columns, in the predetermined arrange-
ment of which there may be discerned the same rela-
tion to the acquisition of strength and power of resist-
ance in the due direction, as in the disposition of the
columns and beams of a work of human architecture.

“ Whoever attentively observes a polished section or
a fractured surface of a human tooth may learn, even
with the naked eye, that the silky and iridescent luster .
reflected from it in certain directions is due to the
presence of a fine fibrous structure.

EARLY MICROSCOPICAL DISCOVERIES, xilt

“ Malpighi,* in whose works may be detected the
germs of many important anatomical truths that have
subsequently been matured and established, says the
teeth consist of two parts, of which the internal bony
layers (dentine) seem to be composed of fibrous and, as
it were, tendinous capillaments reticularly interwoven. .

“Leeuwenhoek,+ having applied his microscopical
observations to the structure of the teeth, discovered
that the apparent fibers were really tubes, and he com-
municated a brief but succinct account of his discovery
to the Royal Society of London, which was published,
together with a figure of the tubes, in No. 140 of their
Transactions. This figure of the dentinal tubes, with
additional observations, again appeared in the Latin
edition of Leeuwenhoek’s works, published at Leyden
in 1730.- The dentine of the human teeth, and also
that of young hogs, is described as being ‘formed of
tubuli spreading from the cavity in the center to the
circumference.’ He computed that he saw a hundred
and twenty of the tubuli within the forty-fifth part of
an inch. He was aware also of the peculiar substance
now termed the cement, or crusta petrosa, which enters
into the composition of the teeth of the horse and the
Ox.

“These discoveries may be said to have appeared
before their time. The contemporaries of Leeuwen-

* An Italian physician ; born in 1628; died in 1694. He was
the first to apply the newly-invented microscope in the study of
anatomy.

{ A Dutch naturalist and manufacturer of optical instruments.
His microscopes were said to be the best in Europe. Besides
his dental discoveries, he discovered the red globules of the
blood, the infusorial anima'cules, and that of the spermatozoa.
Born in Delft October 24, 1632; died there August 26, 1723.

XIV INTRODUCTION.

hoek were not prepared to appreciate them; besides
they could neither repeat nor confirm them, for his
means of observation were peculiarly his own; and
hence it has happened that, with the exception of the
learned Portal,* they have either escaped notice, or
have been designedly rejected by all anatomists until
the time of the confirmation of their exactness and
truth by Purkinjé in 1835.”

Continuing the subject, Prof. Owen further says of
the three constituent parts of teeth—dentine, enamel,
and cement—beginning with —

THE DENTINE.

“Purkinjé states that the dentine consists, not of
superimposed layers, but of fibers arranged in a homo-
geneous intermediate tissue, parallel with one another,
and perpendicular to the surface of the tooth, ranning
in a somewhat wavy course from the internal to the
external surface, and he believed these fibers to be
really tubular, because on bringing ink into contact
with them, it was drawn in as if by capillary attraction.

“On the publication of this discovery, it was imme-
diately put to the test by Prof. Miller, by whom the
tubular structure of the dentine was not only con-
firmed, but the nature and one of the offices of the
tubes were determined. He observed that the white
color of a tooth was confined to these tubes, which were
imbedded in a semitransparent substance, and he found
that the whiteness and opacity of the tubes were re-
moved by acids. On breaking a thin lamella of a tooth
transversely with regard to its fibers, and examining
the edge of the fracture, Miller perceived tubes pro-

* « Histoire de Anatomie et de la Chirurgie,” Paris, 1770.

WHAT THE TUBES CONTAIN. XV

jecting here and there from the surfaces. They were
white and opaque, stiff, straight, and apparently not
flexible. This appearance is well represented in the
old figure by Leeuwenhoek. If the lamellz had been
previously acted upon by acid, the projecting tubes
were flexible and transparent, and often very long.
Hence Miller inferred that the tubes have distinct
walls, consisting of an animal tissue, and tiat, besides
containing earthy matter in their interior, their tissue
is, in the natural state, impregnated with calcareous
salts.” *

THE CEMENT.

“The organized structure and microscopic character
of the cement were first determined by Purkinjé and
Faenkel, and the acquisition of these facts led to the
detection of the tissue in the simple teeth of man and
carnivorous animals, The cement is most conspicuous
where it invests the root of the tooth, and increases in
thickness as it approaches the apex of the root. The
animal constituent of this part. of the cement had been
recognized by Berzelius as a distinct investment of the
dentine long before the tissue of which it formed the
basis was clearly recognized in simple teeth. Berzelius
describes the cemental membrane as being less consist-
ent than the animal basis of the dentine, but resisting

* Tf Lord Bacon’s theory is correct, the probability is that these
tubes contain something besides earthy matter and calcareous
salts, to wit, spirit. In “Novum Organum” he says (B. Mon-
tagu, vol. xiv, p. 417): “All things abhor a sulution of their
continuity, but yet in proportion to their rarity. The more rare
the bodies be, the more they suffer themselves to be thrust into
small and narrow passages; for water will go into a passage
which dust will not go into, air which water will not go into,
and flame and spirit which air will not go into.”

xvi INTRODUCTION.

longer the solvent action of boiling water, and retain-
ing some fine particles of the earthy phosphates when
all such earth had been extracted from the dentinal
tissue. Cuvier also states that the cement is dissolved
with more difficulty in acid than the other dental tis-
sues.. Retzins,* however, states that the earth is
sooner extracted by acid from the cement than from
the dentine of the teeth of the horse.

“Tn recent mammalian cement the radiated cells, like
the dentinal tubes, owe their whiteness and opacity to
the earth which they contain. According to Retzius,
‘numerous tubes radiate from the cells, which, being
dilated at their point of beginning, give the cells the
appearance of an irregular star. These tubes form
numerous combinations with each other, partly direct
and partly by means of fine branches of z54,,th to
sots7th of an inch in diameter. The cells vary in
size. The average size of the Purkinjean cells in hu-
man cement is ;g45,th of an inch. In sections made
transversely to the axis of the tooth, it is clearly seen
that these cells are arranged in parallel or concentric
striz, of which some are more clearly and others more
faintly visible, as if the cement were deposited in fine
and coherent layers’ The layer of cament is found in

'

* Prof. Retzius, of the University of Stockholm, informs us
that he had been led by the iridescence of the fractured surface
of the substance of a tooth to conceive that that appearance was
due, as in the crystalline lens, to a fine fibrous structure, and that
he communicated his opinions as to the regular arrangement of
these fibers to some of his colleagues in 1834, In 1835, having
obtained a powerful microscope, he began a series of more exact
researches on the intimate structure of the teeth in man and
the lower animals, which he communicated to the Royal Acad-
emy of Sciences at Stockholm on January 13, 1836, being then
unacquainted with the discoveries of Purkinjé.—Owen.

-

EXOSTOSIS OF THE ROOT. xvii

the deciduous teeth, but is relatively thinner, and the
Purkinjean cells are more irregular.

“<*In growing teeth, with roots not fully formed,
the cement is so thin that the Purkinjean cells are
not visible. It looks like a fine membrane, and has
been described as the periosteum of the roots, which
are wholly composed of it; but it increases in thick-
ness with the age of the tooth, and is the seat and ori-
gin of what are called exostoses of the roots.’ These
growths are subject to the formation of abscesses, and
.all the morbid actions of true bone.

“It is the presence of this osseous substanee which
renders intelhgible many well-known experiments of
whieh human teeth have been the subjects, such as
their transplantation and adhesion into the combs of
cocks, and the establishment of a vascular connection
between the tooth and the comb.

“Under every modification the cement is the most
highly organized and most vaseular of the dental tis-
sues, and its ehief use is to form the bond of vital
union between the denser and commonly unvascular
constituents of the tooth and the bone in which the
tooth is implanted. In a few reptiles (now extinct),
and in the herbivorous mammalia, the cement not only
invests the exterior of the teeth, but penctrates their
substance in vertical folds, varying in number, form,
extent, thickness, and degree of complexity, and con-
tributing to maintain that inequality of the grinding
surface of the tooth which is essential to its function
as an instrument for the comminution of vegetable
substances.” *

* CEMENT MISTAKEN FOR TARTAR (ODONTON’ITHOS),—Sur-
geon E. Maylfew says (“The Horse’s Mouth,” &c.): “Within
the alveolar cavity, the crusta petrosa, which becames of con-

xvVill INTRODUCTION.

THE ENAMEL.

“The higher an animal is placed in the scale of or-
ganization, the more distinct and characteristic are not
only the various organs of the body, but the different
tissues which enter into their composition. This law
is well exemplified in the teeth, aithough in the com-
parison of these organs we are necessarily limited to
the range of a single primary group of animals. We
have seen, for example, that the dentine is scarcely
distinguishable from the tissue of the skeleton in the
majority of fishes; but that its peculiarly dense, un-
vascular, and resisting structure, which is the excep-
tionable condition in fishes, is its prevalent character
in the teeth of the higher vertebrates.

“So likewise with the enamel. This substance,
which under all its conditions bears a close analogy
with the dentine, is hardly distinguishable from that
tissue in the teeth of many fishes. The fine calciger-
ous* tubes are present in both substances, and undergo
similar subdivisions, the directions only of the trunks

siderable thickness around the root, is of a yellowish-white
color ; but where, as on the crown of the tooth, it is exposed to
the chemical action of food and air, it presents a darker aspect,
and resembles an accumulation of tartar, for which indeed it
has been mistaken. It fills up the infundibula of the grinders
and lines those of the incisors. It is pierced by all the vessels
which nourish the teeth.”

The editor of ‘“‘The Veterinarian” (1849), in a “review” of
Mr. Mayhew’s work, says: ‘‘ Both English and French veteri-
nary writers have mistaken the crusta petrosa for tartar, not be-
ing aware of its existence inside as well as outside of the tooth.”

*This word is peculiar to if not originated by Prof. Owen. It
is synonymous with the word Calciferous (limy).

THE ENAMEL’S VARIEGATED BEAUTIES. XIX

and branches being reversed, agreeably with the con-
trary course of their respective developments. The
proportion of animal matter is also greater in the
enamel of the teeth of fishes than in the higher verte-
brata, and the proportion of the calcareous salts incor-
porated with the animal constituent of the walls of
the tubes is greater as compared with the subcrystal-
line part deposited in the tubular cavities.

“The enamel may be distinguished, independently
of its microscopic and structural characters, by its
glistening, subtransparent substance, which is white
or bluish-white by reflected light, but of a gray-brown
color when viewed, under the microscope, by trans-
mitted light. * * * The enamel of the molar
tooth of a calf, which has just begun to appear above
the gum, and which ean readily be detached from the
dentine, especially near the beginning of the shine is
resolvable into apparently fine prismatic fibers. If
these fibers be separately treated with dilute shied
acid, and the residue examined with a moderate mag-
nifying power, in distilled water, or, better, in dilute
alcoho!, portions of more or less perfect membranous
sheaths or tubes will be discerned, which inclosed the
earthy matter of the minute prism, and served as the
mold in which it was deposited.

“Prof. Retzius, who obtained a small portion of *
organic or animal substance from the enamel-fibers of
an incompletely-formed tooth of a horse, conjectured
that it was a deposition of that fluid which originally
surrounds the loose enamel-fibers, and that ‘in pro-
portion as these fibers are pressed tighter together, and
additional fibers are wedged between them, the organic
deposition js forced away.’

‘“‘Retzius accurately describes the enamel-fibers of

xx INTRODUCTION.

the horse as presenting the form of angular needles,
about </;,th of an inch in diameter, which are trav-
ersed by minute and close-set transverse striz over
the whole or a part of the fiber; and he conjectures
that if the enamel-fiber be a mass of the calcareous
salts, surrounded by an organic capsule, that the stricz
may then belong to the capsule, and not to the enamel-
fiber. The later researches of Dr. Schwann add to the
probability of this conjecture; and the absence of the
minute strie in the enamel of fossil mammalian teeth,
at least in the examples which I have submitted to
microscopic investigation, may depend upon the de-
struction of the original organic constituent of the
enamel.

“The enamel-fibers are directed at nearly right
angles to the surface of the dentine, and their central
or inner extremities rest in slight but regular depres-
sions on the periphery of the coronal dentine. hus
in the human tooth, the fibers which constitute the
masticating surface are perpendicular, or nearly so, to
that surface, while those at the lower part of the crown
are transverse, and consequently have a position best
adapted for resisting the pressure of the contiguous
teeth, and for meeting the direction in which external
forces are most likely to impinge upon the exposed
crown of the tooth. The strength of the enamel-fibers
is further increased by the graceful, wavy curves in
which they are disposed. These curves are in some
places parallel, in others opposed. Their concavities
are commonly turned toward each other, where the
shorter fibers, which do not reach the exterior of the
enamel, abut by their gradually attenuated peripheral
extremities upon the longer fibers. Other shorter fibers
extend from the outer surface of the enamel toward

ENAMEL LINES PARALLEL AND WAVY. Xxi

the dentine, and are wedged into the interspaces of
the longer fibers. In the teeth of fishes, the calciger-
ous tubes or fibers of the enamel, which ramify and
subdivide like those of the dentine, have their trunks
turned in the opposite direction, or toward the periph-
ery of the tooth. So likewise in human teeth the
analogous condition may be discerned in the slightly
augmented diameter of the enamel-fibers at their pe-
ripheral as compared with their central extremities.
When the extremities of the human enamel-fibers are
examined with a magnifying power of 300 linear
dimensions, by reflected light, they are seen to be cv-
adapted, like the cells of a honey-comb, and, like these,
to be, for the most part, hexagonal.

“The internal surface of the enamel is marked by
fine transverse lines or ridges, of which Retzius counted
twenty-four in the vertical extent of one-tenth of an
English inch of the crown of a human incisor. These
lines are parallel and wavy, and, like the analogous
markings on the surface of shells, indicate the succes-
sive formation of the belts of enamel-fibers that encircle
the crowa of the tooth. They may be traced around
the whole crown, but are very faint upon its inner or
posterior surface. Retzius cites Leeuwenhoek as the
discoverer of these superficial transverse lines of the
enamel, but the older observer supposed them to be
indicative of the intervals between the successive move-
ments in the cutting of the tooth through the gum.

“The enamel, by virtue of its physical qualities of
density and durability, forms the chief mechanical
defense of the tooth, and is consequently limited in
most simple teeth to the exterior surface of the exposed
portion of the dentine, forming the crown of the tooth.
* * * In the herbivorous mammalia, with the

Xxli INTRODUCTION.

exception of the Edentata, vertical folds or processes
of the enamel are continued into the substance of the
tooth, varying in number, form, extent, and direction,
and producing, by their superior density and resistance,
the ridged inequalities of the grinding surface on which
its efficacy in the trituration of vegetable substances
depends.”

Dr. Boon Hayes’s thoughts are thus recorded in a
“Medical Circular,” extracts from which appear in
“The Veterinarian” for 1853 (pp. 585-6):

“Tn the first place, observe the pulpal cavity, which
is to the tooth what the medullary cavity is to bone.
Both originate in the same way. Into it passes an
artery, a vein, and a nerve. These ramify upon the
pulpal surface, the artery carrying blood to the denti-
nal tubuli, whence the liguor sanguinis (not blood
corpuscles) proceeds to the nourishment of this ap-
parently inorganic mass.

“Tn the teeth of some animals this cavity seems to
send off diverticula between the dentinal tubuli, as if
for the purpose of supplying them with more vascu-
larity. ‘The dentinal tubes open on the walls of the
pulpal cavity, and thence radiate to the enamel supe-
riorly and the crusta petrosa inferiorly. I think it
would not be difficult to prove that caries of the teeth
more frequently proceeds from inflammation begin-
ning in this cavity than from any other cause.

“When the tubes of the dentine are examined with a
high magnifying power, and by transmitted light, they
appear dark. They are much more minute in diameter
than the blood globules; hence the liquor sanguinis
alone can penetrate them for their nourishment; so

PRIMARY AND SECONDARY CURVES. KXUIE

that the teeth are in the same condition as bone in this
respect. ;

“The dentinal tubes, as before said, appear dark;
the lighter and apparently broader masses are the real
substance of the dentine. In this, and especially near
the layer closest to the enamel, dentinal cells are some-
times seen, which may probably be analogous to the
lacune of bone.

“Tf the dentinal curvatures are examined, it will be
seen that they are of two kinds. One set is in bold
and evident curves; the other is not so evident, but it
exists, nevertheless, and a little patience and a high
magnifying power will demonstrate the fact that its
curves are upon the curves of the first set. The former
are called the primary, the latter the secondary curves
of the dentinal tubuli (in botanical description, a
biserrated leaf). From the tubuli minute bracelets
are given off on the sides, and toward the end the tubes
terminate, either in cells, by anastomosis, or by looping
back upon themselves.

“The cement at first envelops the whole tooth, but
soon wears off the crown and as far down as the neck.
Compared with the dentine and enamel, it is very soft,
and more closely resembles bone; in fact im some ani-
mals it is continuous with the bone of the jaw, thus
proving its identity. It contains lacune and canalic-
uli, and, when there is a large mass of it, something
like Haversian canals.

“There is a great analogy between tooth and bone.
In the cement there is absolute likeness, and in the
dentine analogies too striking to be overlooked, viz.,
the tubuli, analogous to the canaliculi, the intertubular
cells, analogous to the lacune, and the intertubular
substance, analogous to the laminz of bone. In the

XXIV INTRODUCTION.

enamel the greatest departure is observable, but not
wider than its peculiar function suggests; and it must
be remembered, first, that it is the least constant tissue
of the teeth; secondly, that its chemical composition
is very much the same as that of the dentine and
cement, both of which resemble bone. Lastly, the
analogy is completed in a review of the mode of tooth
development. ‘Thus, upon a mucous papilla a large
quantity of gelatinous matter is observable, in which
certain cellsappear. The gelatinous matter resembles
the incipient cartilage in which ossification begins.
This papilla is supplied with an artery, which nour-
ishes its cells, and the cells gradually so develop that
the older ones are pushed outward and form the
dentine.”

HOW MADDER AFFECTS THE TEETH.

John Hunter, one of the most celebrated physiolo-
gists of the eighteenth century, made many experi-
ments on the teeth of different animals, one object
being to determine whether they were vascular or not.
His conclusion was that they were not vascular, and
he founded his belief partly upon the following experi-
ment (“The Human Teeth,” pp. 23-4):

“Take, for example, any young animal, as a pig, and
feed it with madder for three or four weeks; then kill
it. On examination you will find the following ap-
pearances: First, if the animal had some parts of its
teeth formed before the feeding with madder, they
will be known by their remaining of the natural color;
but such parts of the teeth as were formed while the
animal was taking the madder will be of a red color.
This shows that it is only those parts that were formed
while the animal was taking the madder that are dyed ;

RED, WHITE, GOLDEN, AND SILVER HUES. xxv

for what were already formed will not be in the least
tinged. ‘This is different in all other bones; for we
know that any part of a bone which is already formed
is capable of being dyed with madder, though not so
fast as the part that is forming. ‘Therefore, as we know
that all other bones are vascular, and are thence sus-
ceptible of the dye, we may readily suppose that the
teeth are not susceptible of it after being once formed.
But we shall carry this a step further: If you feed a
pig with madder for some time, and then leave it off
for a time before killing it, you will find the appear-
ances as above, with this addition, that all the parts of
the teeth which were formed after leaving off feeding
with the madder will be white. Here, then, in some
teeth we shall have white, then red, and then white
again; and so we shall have the red and white colors
alternately through-the whole tooth.*

“'l'his experiment shows that a tooth, once tinged,
does not lose its color. Now, as all other bones that

*In the concluding part of Moore’s “ Lalla Rookh” (“The
Light of the Harem”), the Enchantress says of an herb with the
unmusical name of ‘‘ Haschischat ed dab :”

‘* The visions, that oft to worldly eyes
The glitter of mines unfold,
Inhabit the mountain-herb, that dyes
The tooth of the fawn like gold.”

A reference note to the above is as follows: “An herb on
Mount Libanus, which is said to communicate a yellow golden
hue to the teeth of the goats and other animals that graze upon
it. Niebuhr thinks this may be the herb which the Eastern
alchemists look to as a means of making gold. ‘Most of those
alchemical enthusiasts think themselves sure of success if they
could but find out the herb which gilds the teeth and givesa yel-
low color to the flesh of the sheep that eat it. Even the oil of this
plant must be of a’go!den color. It is called Huschischat ed dab’
Father Jerome Dandini, however, asserts that the teeth of the

XXvVl1 INTRODUCTION.

have been tinged lose their color in time, when the
animal leaves off feeding with the madder (though
very slowly), and as that dye must be taken into the
constitution by the absorbents, it seems that the teeth
are without absorbents as well as other vessels.”

The editor of Hunter’s “ Treatise,’ Thomas Bell,
F.R.S., differed with Hunter about the vascularity of
the teeth. He thus concludes a note on the above
quotation :

“The truth appears to be that the teeth are organ-
ized bodies, having nerves and absorbent and circula-
ting vessels, but possessing a low degree of living
power, and so dense a structure as to exhibit phenom-
ena, both in their healthy and diseased condition,
which are very dissimilar from those which are ob-
served in true osseous structures.”

TRANSPLANTING TEETH.

The transplanting of teeth, which Dr. Hunter says
is “similar to the ingrafting of trees,” is expatiated
upon at some length. He then gives an account of a
case of transplanting which he admits “is not gener-
ally attended with success,” he having “succeeded but
once out of a great number of trials.” It is as follows
(“The Human Teeth,” pp. 100-101):

‘T took a sound tooth from a person’s head; then

goats at Mount Libanus are of a silver color, and adds: ‘This
confirms to me that which I observed in Candia, to wit, that
the animals that live on Mount Ida eat a certain herb which
renders their teeth of a golden color, which, according to my
judgment cannot otherwise proceed than from the mines which
are under ground.’—Dandini, Voyage to Mownt Libanus.”

GRAFTING GERMS OF DOGS’ TEETH. Xxvii

made a wound in a cock’s comb, pressed the root into
it, and fastened it with threads. ‘The cock was killed
some months affer, and I injected the head with a very
ininute injection. I then put the comb into a weak
acid. The tooth was softened, and I divided it longi-
tudinally. Its vessels were well injected, the external
surface adhering to the comb by vessels similar to the
union of a tooth with the gum and sockets.” *

* MM. E.Magitot, C. Legros, and C. Robin have experimented
in transplanting the follicles or germs of dogs’ teeth, an account
of which appears in “Comptes Rendus” for 1874, They say:

“Our experiments comprised 88 grafts, mostly from newly-born
dogs, but some were 22 and even 58 days old. The animals
were invariably sacrificed by the pricking of the bulbs, and
the jaws were opened at once, to lay the follicles bare. One-half
of both jaws thus served to supply the grafts, while the other
was kept for a standard of comparison. The dogs on which the
grafts were applied were usually adults, but sometimes of the
same age and bearing as those that supplied them. The germs
were rapidly isolated from the dental gutters, and introduced at
once. In some instances they were dipped for a few minutes in
the blood’s serum of the sacrificed animal, which was kept by
the bath (bain-marie) at a temperature of from 30° to 35° C.
They were introduced under the skin of the nape of the neck,
the top of the head, and the dorsal and lumbar regions. In 36
cases the process of application consisted of a simple incision and
the introduction of the graft 2 or 3 centimeters from the open-
ing, which was closed by two sutural stitches. In the other 52
cases a special trocar of an interior diameter of 7 millimeters was
used, which allowed a swifter and surer transplantation, but it
did not appear to exert an appreciable influence on the results.

“Ten grafis were made from newly-born dogs on adult guinea-
pigs, divided as follows: Whole follicles, 6; isolated enamel-
organs, 3; bulbalone,1. The results were all negative—caused
_ by resorption and suppuration—corroborating M. Bert’s experi-
ences in grafis between animals of different zoological orders.

“The 78 other grafts were made on newly-born, young, and
adult dogs, and were maintained from 13 to 54 days. The 25
grafts that remained 54 days resorbed themselves. The expeti-
ments in detail were as follows: 1. Isolated whole follicles, 26.
2. Follicles with a portion of the maxillary bone, 5. 3. Isolated

XXvili INTRODUCTION.

This appears to prove that Dr. Hunter was right
when he said that teeth “are capable of uniting with

bulbs, 16. 4. Bulbs with a cap of rudimentary dentine, 7. 5.
Isolated caps of dentine, 4. 6. Isolated enamel-organs, with a
shred of buccal mucous membrane, 19. 7. Enamel-organs, with
a cap of dentine adhering, 1. The results were: Of the first, 7
kept alive and grew steadily, except in one instance, in which a
disturbed nutrition brought on the formation of globulary den-
tine and irregular stacks of enamel prisms. The second gave 3
suppurations and 2 resorptions, again corroborating Mous. Bert’s
experiments. The third gave 3 positive results, in two of which
a new cap of dentine was produced, quite rezular, but globulous
and somewhat altered in its nutrition, The other was without
enamel. In the fourth experiment the bulbs could not be found;
they underwent resorption. When compared with the preced-
ing experiment, this result is astonishing ; but it should be un-
derstood that these grafts were maintained from 438 to 54 days,
Of the fifth a single one kept alive, but without showing any
growth, It remained stationary 43 days. The sixth invariably
ended in resorption, notwithstanding we were careful to graft
the shred of mucous membrane, which supplies the organ with
nutritive vessels. This resuit is not surprising when the exces-
sive frailty of this tissue and its lack of vascularity are consid-
ered. Some of the negative grafts were either reduced in size,
being evidently in process of resorption, or underwent the oily
transformation. Others caused abscesses, and were eliminated.
“ Conelusions.—1. The grafts gave favorable results only be-
tween animals of the same zoological order. 2. The isolated
whole follicles and bulbs may live and develop themselves. 3.
The transplanting of more or Jess voluminous portions of jaws
with the follicles failed through suppuration or resorption. 4.
The grafts of the eaamel-organ, isolated, seem invariably given
up to resorption. 5. Under certain circumstances the growth is
regular, with no other difference from that in the normal state
than a noticeable slowness in the phenomena of evolution. 6.
Under other circumstances there is trouble in the formation of
the dentine and enamel, the study of which, however, may be ap-
plied to the elucidation of the phenomena, still so dark, of tooth
development. 7. The experiments are an acquisition to the lit-
erature of and may be compared with other surgical grafts.” *

* For the translation of the above interesting article (from the Reports of
the French Academy) I am indebted to Monsieur C. Raoux, of New York.

THE TEETH LIVING ORGANISMS. XX1X

any part of a living body.” Mr. Bell thus concludes
a note on the above case of transplanting:

“The experiment has an interest attached to it far
more important than its having given rise to the tem-
porary adoption of an objectionable operation. In the
result of this experiment may be found an interesting
collateral argument in favor of the organized structure
of the teeth, and their actual living connection with
the body. The vessels of the tooth, we are told, were
well injected, and the external surface adhered every-
where to the comb by vessels. To what purpose are
these vessels formed, what object can be possibly ful-
filled by the existence of a vascular pulp in the internal
cavity, and a vascular periosteum covering the external
surface—so obviously vascular that it was wed/ injected
from the vessels of a cock’s comb, into which it had
been transplanted—unless they are intended to nourish
the bony substance of which the tooth consists, and to
form the medium of its connection with the general
system ?”

Prof. Richard Owen says (“ Odontography,” vol. i,
p- 470):

“The saving of material is the least of the benefits
gained by this tubular structure of the dentine. The
vitality of the tissue, which Hunter recognized so
forcibly, but which, being equally convinced of the
non-vascularity of the tissue, he was unable to explain
—‘willing rather to enunciate an apparent paradox or
be taunted with dilemma, than yield one iota of either
of his convictions’ *—is explicable by the possible and

* Prof. Owen quotes from Bell’s “ notes” in Hunter’s “ Human
Teeth.”

XXX INTRODUCTION.

highly probable fact of a circulation of the colorless
plasma of the blood through the dentinal tubes. That
some elementary prolongations of nerve may also be
continued into these tubes, who can confidently deny ?”

As Pref. Owen says the “teeth are always most
intimately related to the food and habits of the ani-
mal,’ it would be interesting and perhaps useful to
ascertain what effect sugar and other unusual articles
of diet would have on horses’ teeth. In the interest
of science, experiments appear to be in order. In this
connection the following paragraph, a part of which
may be found in Prof. William Youatt’s work, “The
Horse” (p. 135), the remainder in “ The Veterinarian,”
is interesting:

“Surgeon Black, of the Fourteenth Dragoons, says
that sugar was tried as an article of food during the
Peninsular War. Ten horses were selected, each of
which got eight pounds a day. They took it very
readily, and their coats became fine, smooth, and
glossy. They got no corn, and only seven pounds of
hay instead of twelve, the ordinary allowance. ‘The
sugar supplied the place of corn so well, that it would
probably have been given abroad ; but peace came, and
with it corn. The horses returned to their usual diet,
but several of them became crib-biters. The experi-
ment was made at the Brighton dépdét, during a period
of three months. To prevent the sugar from being
used for other purposes, it was scented with assafetida,
but the latter did not produce any apparent effect on
the horses.”

HORSES? -TEETH.

ChoaAtrtTE nf.
TOOTH-GERMS (ODONTOGENY).

Periods at which the Germs are visibie in the Fetus—Dentine
and Enamel Germs,—A Cement Germ in the Foal.—The
Horse’s Upper Grinders said to be developed from Five
Germs, the Lower from Four. —Similar development of the
Human Teeth.— Monsieur Magitot’s Researches.

Furrows in what is subsequently transformed into
jawbones, in which tooth-germs are, as it were, planted,
are Nature’s first visible preparation for the develop-
ment of the teeth. According to Prof. William You-
att, the germs of the temporary teeth are visible seven
or eight months before the foal is born. Three months
before its birth the germs of the permanent teeth are
also visible, a distinct partition separating them from
the temporary. At this time, according to Veterinary
Dentist C. D. House, the capsules or bags (also called |
follicles, sacs, &c.), containing the tooth-pulps* of the

* The pulp in the cavity of a ful’-grown tooth is a delicate
mass of connective tissue, containing both blood-vessels and
nerves. Its external layer consists of large nucleated cells, the
odontoblasts, provided with long branching processes which line
the dental canals. Boll thinks the nerves’ delicate terminal
fibrils accompany the processes into the canals.— Woodward.

For development of elephant tooth-germs see Appendix.

32 TOOTH-GERMS.

future temporary teeth are about the size of small peas.
They will bear some pressure between the fingers, the
indentions springing back like those of an India rub-
ber ball.

The nature of tooth-germs and the development of
teeth have been studied with some diligence by scien-
tific men—Dr. John Hunter, it is said, making the first -
imvortant discoveries in connection with the science.
The discussion of this interesting and, to students,
useful subject is left to these men. There is some
conflict in their views, but it should be remembered
that the extracts reflect the opinions of men from
Hunter’s time (over a century ago), to 1876. The de-
velopment of tooth-germs being the same in principle
(though different in detail) in all mammals, the matter
which follows (as has been said of that in the “ Intro-
duction”), is as applicable to the horse as to man.

In the Introduction to his “ Odontography ” (Lon-
don, 1844), Prof. Richard Owen says:

“In the development of a tooth a matrix of equal
complexity was first recognized to be concerned by
John Hunter, the several parts of this matrix being
first distinctly indicated in the ‘Natural History of
the Human Teeth.” * * * Hunter has been gen-
erally regarded by physiologists as being the author of
the theory that the pulp stood to the tooth-bone in the
relation of a gland to its secretion; that the formative
virtue of the puip resided in its surface; that the den-
tine was deposited upon and by the formative or secre-
tive surface in suecessive layers, and that the pulp,
exhausted, as it were, by its secretive activity, dimin-
ished in size as the formation of the tooth proceeded,
except in certain species, in which it was persistent,

JCIIN HUNTER’S DISCOVERY. 33

and maintained an equable secretion of the dentine
throughout the lifetime of the animal. This idea of
the pulp’s function has predominated in the minds of
most subsequent writers on the development of the
tecth. * ¥ " *

“'Phree formative organs are developed for the three
principal or normal dental tissues, the ‘dentinal-pulp,’
or pulp proper, for the dentine, the ‘capsule’ for the
cement, and the ‘enamel-pulp’ for the enamel. The
essential fundamental structure of each formative
organ is cellular, but the cells differ in each organ,
and derive their specific characters from the properties
and metamorphoses of their nucleus, upon which the
specific microscopical characters of the resulting calci-
fied substances depend.

“In the cells of the dentinal-pulp the nucleus fills
the parent cell with a progeny of nucleoli before the
work of calcification begins. In the enamel-pulp the
nucleus of the cell disappears, like the cytoblast of the
embryo plant in the formation of most vegetable tis-
sues. In the cells of the capsule the nucleus neither
perishes nor propagates, but retains its individuality,
and gives origin to the most characteristic feature of
the cement, viz., the radiated cells.

“The primordial material of each constituent of the
tooth-matrix is derived from the blood, and special
arrangements of the blood-vessels preéxist to the devel-
opment and growth of the constituent substances. A
pencil of capillaries is directed to a particular spot in
the primitive dentiparous groove, and terminates there
by a looped network, from which spot a group of nu-
eleated cells begins to arise in the form of a papilla.

a ORS. % a st xk

“The primary dentinal papilla and its capsule rap-

34 TOOTH-GERMS.

idly increase by successive additions of nucleated cells,
apparently derived from material supplied by the cap-
illary plexus at the base. The capillaries now begin
to penctrate the substance of the pulp itself, where
they present a subparallel or slightly diverging pencil-
late arrangement, but preserve their looped and retic-
ulate termination near the apex of the pulp. Fine
branches of nerves accompany the capillaries, and ter-
minate also in loops. * * * The primary cells and
the capillary vessels and nerves are imbedded in and
supported by a homogeneous, minutely subgranular,
mucilaginous substance, the ‘blastema. * * * The
vascularity of the dentinal-pulp, and especially the
rich network of looped capillaries that adorns the
formative peripheral layer at the period of its func-
tional activity, have attracted general notice, and have
been described by Hunter and subsequent authors. By
most this phenomenon has been regarded as evidence
of the secreting function of the surface of the pulp,
and the dentine as an outpouring from that vascular
surface which was supposed to shrink or withdraw
from the matter exereted. iy _ *
“The enamel-pulp differs from the dentinal-pulp at
its first formation by the more fluid state of its blas-
tema, and by the fewer and more minute cells which
it contains. The source of this fluid blastema appears
to be the free inner vascular surface of the capsule.
As it approaches the dentinal-pulp the blastema ac-
quires more consistence by an increased number of its
granules, and it contains more numerous and larger
cells) Many of these show a nuclear spot, others a
nucleus and nucleolus. The spherical nucleolar cells
in the part of the blastema further from the capsule
are so numerous as to form an aggregate mass, with a

DEFINING THE BLASTEMA. 35

small quantity of the condensed blastema in the
minute iterspaces left between the cells, which are
pressed together into hexagonal or polygonal forms.
* %* * The field of the final metamorphosis of the
cells into the molds for the reception of the solidifying
salts is confined to close contiguity with the surface of
the dentinal-pulp. Here the cells increase in length,
lose all trace of their nucleus, and become converted
into long and slender cylinders, usually pointed at both
ends, and pressed by mutual contact into a prismatic
form. These cylinders have the property of imbibing
the calcareous salts of the enamel from the plasmatic
fluid, and of compacting them in a clear and almost
erystalline state im their interior. Ls * ¥
“The blastema or fundamental tissue of the capsule
is, at first, semitransparent and of a pearly or opaline
color, but 1s soon richly ornamented by the plexiform
distribution of the blood-vessels. As the period of its
calcification approaches, which 1s later than that of
the dentinal-pulp, it becomes denser, and exhibits nu-
merous nucleated cells. The blastema itself presents
more evidently a fine cellular or granular structure, in
which the calcareous salts are impacted in a compara-
tively clear state, constituting the framework of the
cemental tissue. The characteristic features of this
tissue are due to the action of the proper nucleated
cells upon the salts of the plasma diffused through the
blastema in which those cells are imbedded, the cells
being characterized by a single, large, granular nu-
cleus, which almost fills the clear area of the cell itself.
If, when the formation of the cement has begun in the
incisor or molar of a colt, one of the detached specks
of that substance, with the surrounding and adhering
part of the inner surface of the capsule in which 1t is

36 TOOTH-GERMS.

imbedded, be examined, the nucleated cells are seen,
closely aggregated around the calcified part, in con-
centric rows, the cells of which are further apart as
the rows recede from the field of calcification. ‘Those
next the cement rest in cup-shaped cavities in the
periphery of the calcified part, just as the first calcified
cells of the thick cement which covers the crown of a
complex molar are lodged in cavities on the exterior of
the enamel. These exterior cavities of the cement are
formed by centrifugal extension of the calcifying pro-
cess in the blastema in which the cells are imbedded.
The calcareous salts penetrate in a clearer and more
compact state the cavity of the cell, but their progress
is arrested apparently by the nucleus, which maintains
an irregular area, partly occupied by the salts in a sub-
granular, opake condition, but chiefly concerned in
the reception and transit of the plasmatic fluid, which
enters and escapes by the minute tubes that are sub-
sequently developed from the nucleolar cavity as calci-
fication proceeds.

“The radiated cells or cavities thus formed are the
most common characteristic of the cement, but not the
constant one. The layer of the capsule which sur-
rounds the crown of the human teeth and of the
simple teeth of quadrumana and carnivora, consists
simply of the granular blastema, without nucleated
cells, and the radiated corpuscles are, consequently, not
developed in the cement which results from its calci-
fication. In the thicker part of the inflected folds of
the capsule of the complex teeth of the herbivora,
traces of the vascularity of that part of the matrix’ are
persistent, the blastema calcifying around certain of
the capillaries, and forming the medullary canals.
The varieties of these canals are traversed by minute

PROF. TOMES’S THEORY. 37

tubules, continued from or communicating with the
radiated cells. These tubules, and the more parallel
ones which traverse the thickness of the cement in
many mammalia, are the remains of linear series of
the minute granules of the blasteema. * * = #*
“The general form of the dental matrix and its rela-
tion with its calcified product, bear a close analogy
with those of the formative organ of hairs, bristles, and
other productions of the epidermal system. In these
the papilla, or pulp, is developed from the external
skin; in the teeth, from the mucous membrane, or
internal skin.” * * * *

Prof. Charles 8. Tomes, among dentists a recognized
authority, differs with Messrs. Hunter and Owen as
to the pulp’s secretive office, claiming that a tooth is
formed by a partial metamorphosis of its pulp. He
says (“ Manual of Dental Anatomy, Human and Com-
parative,” pp. 104-5-6) :

“Prior to the beginning of any calcification, there
is always a special disposition of the soft tissues at the
spot where a tooth is destined to be formed, and the
name of ‘ tooth-germ’ is given to those portions of the
soft tissue which are thus specially arranged. All, or
a part only, of the soft structures making up a tooth-
germ become converted into the dental tissue by a
deposition of salts of lime within their own substance,
so that an actual conversion of at least some portions
of the germ into tooth takes place. The tooth is not
secreted or excreted by the germ, but an actual meta-
morphosis of the latter takes place.

“The principal tissues, namely, dentine, enamel, and
cement, are formed from different parts of the tooth-
germ; hence We are accustomed to speak of the enamel-

38. - ‘ TOOTH-GERMS.

germ and the dentine-germ. The existence of a spe-
cial cement-germ is very doubtful, some writers assert-
ing, others denying its existence. ~ " ss

“'Pooth-germs are never formed upon the surface,
but are situated a little distance beneath it, lying in
some animals at a considerable depth. Every known
tooth-germ consists in the first instance of two por-
tions, and two only, the enamel and dentine germs.
These are derived from distinct sources, the former
being a special development from the epithelium of
the mouth, the latter from the more deeply lying parts
of the mucous membrane. Other things, such as a
tooth-capsule, may be subsequently and secondarily
formed. The existence of an enamel-organ in an early
stage is independent of any subsequent formation of
enamel by its own conversion into a calcified tissue, for
I have shown it to be found in the germs of teeth
which have no enamel; in fact, in all tooth-germs
whatever.

“That part of the tooth-germ destined to become
dentine is often called the dentine papilla, having
acquired this name from its papilliform shape; and in
a certain sense it is true that the enamel-organ is the
epithelium of the dentine papilla. Yet, although not
absolutely untrue, such an expression might mislead
by implying that the enamel organ is a secondary de-
velopment, whereas its appearance is contemporaneous
with, if not antecedent to, that of the dentine-germ.
The most general account that Iam able to give of the
process is, that the deeper layer of the oral epithelium
sends down into the subjacent tissue a process, the
shape and structure of which is, in most animals, dis-
tinguishable and characteristic before the dentine-
germ has taken any definite form. This process en-

THE ORAL EPITHELIUM. 39

larges at its end, and, as seen in section, becomes
divaricated, so that it bears some resemblance to an
inverted letter Y ; or it might be better compared to a
bell-jur with a handle. This constitutes the early stage
of an enamel-germ, while beneath it, m the mucous
tissue, the dentine-germ assumes its papilliform shape.
The details of the process varying in different animals,
I will at once proceed to the description of the devel-
opment of teeth in the various groups.”

Prof. Tomes’s views of the development of tooth-
germs in mammals are thus summarized by himself
(“Philosophical Transactions Royal Society,” 1875,
part i, p. 285):

“1, There is never, at any stage, an open groove
from the bottom of which papille rise up.

«2, That the first recognizable change in the region
of a forming tooth-germ is a dipping down of a process
of the oral epithelium, looking, in section transverse
to the jaw, like a deep simple tubular gland, which
descends into the submucous tissue, and ultimately
forms the enamel-organ.

“3. That subsequently to the descent of the so-called
enamel-germ, the changes in the subjacent tissue re-
sulting in the formation of the dentine papilla take
place opposite to its end, and not at its surface.

“4. That the permanent tooth-germs first appear as
offshoots from the epithelial process concerned in the
formation of the deciduous tooth-germ (Kdlliker), the
first permanent molar being derived from a primary
dipping down (like a deciduous tooth), the second de-
riving its enamel-germ from the epithelial neck of the
first, and the third from that of the second (Legros
and Magitot).”

40 TOOTH-GERMS.

Again, in the Society’s Transactions for 1876 (p. 265),
Prof. Tomes says:

“1. It is desirable to abandon the terms ‘papillary,’
‘follicular,” and ‘eruptive’ stages, inasmuch as they
are hypothetical and arbitrary, and correspond to no
serial conditions verified by observation.

“2. In all animals a tooth-germ consists primarily
of two structures, and only two—the dentine-germ
and the enamel-germ. The simplest tooth-germ never
comprises anything more. When a capsule is devel-
oped, it is derived partly from a secondary upgrowth
of the tissue at the base of the dentine germ, and partly
from an accidental condensation of the surrounding
connective tissue.

“3. The existence of an enamel-organ is quite uni-
versal, and is in no way dependent on the presence or
absence of enamel on the completed tooth, although
the degree to which it is developed has distinct relation
to the thickness of the future enamel.

“4, So far as my researches go, a stellate reticulum,
constituting a large bulk of the enamel-organ, is a
structure confined to the mammalia. (It is absent in
the armadillo, and I should infer from Mr. Turner’s
description, in the narwhal also).

“5. As laid down by Profs. Huxley and Kolliker,
the dentine-papilla is beyond all question a dermal
structure, the enamel-organ an epithelial or epidermic
structure. As I believe it can be shown that the enamel
is formed by an actual conversion of the cells of the
enamel-organ, this makes the dentine a dermal and
the enamel an epidermic structure.

“6. In teleosts the new enamel-germs are formed
directly from the oral epithelium. They are new for-
mations, and arise quite independently of any portion

MONSIEUR CHAUVEAU’S THEORY. 41

of the germs of the teeth which preceded them. In
mammals and reptiles, and in some of the batrachia,
new tooth-germs are developed from portions of their
predecessors.

“7. In all animals examined the phenomena are very
uniform. A process dips in from the oral epithelium,
often to a great depth, its end beeoming transformed
into an enamel-organ coincidentally with the formation
of a dentine-papilla beneath it. The differences lie
rather in such minor details as the extent to which a
capsule is developed, and therefore no such generali-
zation as that the teeth of fish im their development
represent only an earher stage of the development of
the teeth of mammatlia can be drawn.”

Monsieur A. Chauveau’s theory of the development
of tooth-germs is as follows (“ Comparative Anatomy
of the Domesticated Animals,” p. 921):

“The teeth are developed in the interior of a cavity,
named the dental follicle or sac, by means of the ele-
ments of three germs, one belonging to the dentine,
another to the enamel, and a third to the eement. The
dental follicle is an oval cavity, with walls composed of
two layers. The external is fibrous and complete; the
internal, soft and gelatinous, is alhed at the bottom to
the dentine-germ. The latter is a prominence, which
is detached from the bottom of the follicle, and has
the exact shape of the tooth. Its structure eomprises,
in the center, delicate conneetive tissne, provided with
vessels and nerves, and on the surface a layer of elon-
gated cells. At the summit of the follicle, facing the
dentine-germ, is the enamel-germ. It is exaetly ap-
plied to the dentinal-pulp, which it invests like a cap,

42 TOOTH-GERMS.

and is composed of a small mass of mucous connec-
tive ttssue, covered by a layer of cylindrical cells, and
joined to the buccal epithelium by the gubernaculum
dentis.* According to Monsieur Magitot, the cement-
organ manifesily exists in the foal. ‘The base of the
dentine-germ has been found, but it disappears rapidly
after having performed its function.

“Development of the Dental Follicle—On the free
borders of the maxille, the epithelium of the buccal
mucous membrane forms an elongated eminence—the
denta! ridge. Below this ridge the epithelium consti-
tutes a bud, which develops in size, and is sunk in the
mucous membrane. This isthe enamel-germ. I¢ has
a layer of cylindrical cells on its deep surface, and in
its center are round cells. After a certain time it is
only joined to the epithelium, as already said, by a very
thin line of cells, the gubernaculum dentis. While this
enamel-germ grows downward, it covers, by its base, a
connective bud which rises from the mucous derma.
The two buds are reciprocally adapted to each other,

* Concerning the gubernaculum dentis Prof. C. 8. Tomes says
(“ Denial Anatomy,” p. 135): “ Another structure, once thought
to be important, but now known to be a mere bundle of dense
fibrous tissue, is the ‘gubernaculum.’ The permanent tooth
sacs, during their growth, have become invested by a bony shell,
which is complete, save at a point near their apices, where there
isafora’men. Through this feramen passes a thin fibrous cord,
very conspicuous when the surrounding bone is broken away,
which is called the gubernaculum, from the notion entertained
by the older anatomists that it was concerned in directing or
effecting the eruption of the tooth. The gubernacula of the
front permanent tooth sacs perforate the alveolus and blend with
the gum behind the necks of the corresponding milk teeth,
those of the bicuspids uniting with the periosteum of the alveoli
of their deciduous predecessors.”

THE DENTINE-GERM TOOTH-SHAPED. 43

and around them the connective tissue condenses and
gives rise to the walls of the follicle. 1t will therefore
be seen that the enamel-organ is a dependency of the
epithelium, and the dentine-organ a production of the
mucous derma.

“Formation of the Dentine, Hnamel, and Cement.—
As before said, the germ of the dentine has exactly the
form of the future tooth; consequently the dentine
which arises from its periphery presents the shape of
a tooth also. The dentine and enamel are developed
by the modification of the elements situated at the
surface of their germs. The dentine is constituted of
the cells of the germ, which send out ramifying and
communicating prolongations—the dentinal fibers—
and by an intercellular substance, which is impreg-
nated with caleareous matter, and which, being molded
around the fibers, forms canaliculi. The enamel is
derived from the deep cells of its germ, which are
elongated and prism-shaped, and are calcified in be-
coming applied to the surface of the dentine. Tne
cement is developed at the expense of the walls of the
follicle, according to the mode of ossification of the
connective tissue.

“Fruption—As the dentine is formed, the tooth
increases in length and presses the enamel-germ up-
ward. The latter, constantly compressed, becomes
atrophied, and finally disappears when the tooth has
reached the summit of the follicle. In the same way
the young organ pierces the dental follicle and gum
and makes its eruption externally.

“Such is the mode of the development of the tem-
porary teeth, and the permanent ones are formed in the
same manner. During the development of the germ
of the temporary tooth, a bud is seen detaching itself

44 TOOTH-GERMS.

from this germ and passing backward, to serve, at a
later period, in forming the permanent tooth.”

In another part of his work Prof. Chauveau says:

«he follicle in which the incisor teeth are devel-
oped shows only two papilla. One, for the secretion
of the dentine, 1s lodged in the internal cavity of the
tooth, and is hollowed into a cup-shape at its free ex-
tremity; the other is contained in the external cul-de-
sac.”

In describing the simplicity of the structure of the
horse’s canine teeth (tushes), Prof. Lecoq says:

«The disposition of the developing follicle is in har-
mony with the simplicity of their structure. At the
bottom there is a simple and conical papilla for the
internal cavity; on the inner wall, a double longitu-
dinal ridge, on which are molded the ridge and grooves
on the inner face of the tooth.”

Prof. William Youatt’s theory of the development
of horses’ teeth is unique. He is probably correct
about the bones or processes being separate, and his
claim that they are solidified by the cement is certainly
philosophical ; but he differs from all other authorities
about the enamel completing the formation of the
tooth, for it is a well-known fact that a virgin tooth
is enveloped by cement (its protecting varnish), which
wears off as soon as the tooth is brought into use. He
says (“The Horse,” p. 223):

“ A delicate membranous bag, containing a jelly-like
substance, is found in a little cell within the jawbone
of the unborn animal. It assumes by degrees the
shape of the tooth, and then the jelly begins to change

GREAT USE OF THE CEMENT. 45

to bony matter. A hard and beautiful crystallization
is formed on the membrane without, and so we have
the cutting tooth covered by its enamel.

“Tn the formation of the grinders there are origin-
ally five membranous bags in the upper jaw and four
in the lower. ‘The jelly in them
gives place to bony matter,
which is supplied by little ves-
sels, and which is represented
by the darker portions of the
cut with central black spots.
The crystallization of enamel
may be traced around each of the bags, and there
would be five distinct bones or teeth but for the fact
that a third substance is now secreted. (It is repre-
sented by the white spaces). It is a powerful cement,
and through its agency the bones are united into one
body, thus making one tooth of the five. This being
done, another coat of enamel spreads over the sides,
but not the top, and the tooth is completed.”

Dr. Robley Dunglison’s theory of the development
of the human teeth is in principle the same as Prof.
Youatt’s theory regarding those oi the horse. In his
“Medical Dictionary,” article “teeth,” he says:

“The incisor and canine teeth are developed by a
single point of ossification, the lesser molars by two,
and the larger by four or five.”

Surgeons M. H. Bouley and P. B. Ferguson believe
that the teeth are the combined product of the seere-
tion of the pulp and of the membrane which lines the
alveolar cavities. They say that the question as to
whether the sensibility of the teeth is inherent in the
dental substance itself, or resides exclusively in the

46 TOOZH-GERMS.

pulp, is a physiological point of which a satisfactory
solution remains to be given.* )

* Of the development of teeth in the human fetus Monsieur
E. Magitoi says (“Comtes Rendus,” 1874): “Seventh Week—
The epithelial eminence and epithelial inflection of Kolliker
only may be seen at the edge of the jaw. The superior maxil-
lary and intermaxillary bones are not united, and the inferior
maxillary arch contains Meckel’s cartilage only, without any
trace of bone. The epithelia! bands (enamel-organs) are'succes-
sively formed in the order of their designation. MNinth—The
dentine bulb appears in juxtaposition with the downward ex-
tremity of the enamel-organ. This stage occurs nearly simul-
taneously for the whole series of tempo...7 follicles. Tenti—
The wall of the follicle detaches itself from the base of the bulb
' and rises up its sides. Fifteenth—The epithelial band begins
its transformation into an enamel-organ. The enamel-germ of
the first permanent molar may now be seen springing from the
epithelial inflection. Sivteenth—The wall of the follicle is
closed. The epithelial band is broken, and the follicle thencefor-
ward has no connection with the surface epithelium. The epi-
thelial bands of the permanent teeth, which are derived from the
necks of the enamel-organ of the corresponding deciduous teeth,
appear. Svventeenth—Appearance of the cap of dentine of the
central and lateral incisors ; also the bulb of the first permanent
molar. Hiyhteenth—Appearance of the dentine caps of the first
and second molars ; also the wall of the follicle of the perma-
nent molar. Twentieth—Hight of the dentine caps of the cen-
tral incisor, lateral incisor, and canine, .059; first and second
molars, .089. Appearance of dentine organ of permanent teeth,
and inclosure of wali and rupture of band of first molar. Tiventy-
fisth—Dentine cavs, .07, .054. The permanent follicle walls,
which appeared after the twenty-first week, lave acquired a cer-
tain distinctness. Jwety-ecghth—Dentine caps, .095, .078. The
epithelial germs of the permanent follicles begin their transfor-
mation into enamel-organs; dentine cap first molar, .003 to .007.
Thirty-sccond—Dentine caps, .113, .093. The first permanent
molar cusps, which form upon the several apices of the dentine
organ, have coalesced. Thirty-siath—Dentine caps, .118, .109 ;
permanent molar, .004 to .039. Thirty-ninth—Dentine caps,
.136, 118; permanent molar, .039 to .073. The permanent follicle
walls close. The dentine caps appear one month after birth.”

CHAPTER II.
THE TEMPORARY DENTITION.

Twelve Incisors and Twelve Molars—Why the Incisors are
called “ Nippers.”—The Treatment of Foals Affects Teeth-
ing— Roots of Milk Teeth Absorbed by the Permanent.
—Tbe Tushes.

Tue foal’s temporary teeth (known also as milk or
deciduous teeth) are adapted in size and number to
the capacity of the jaws and the amount and nature
of the mastication required for its sustenance. There
are only twenty-four temporary teeth functionally de-
veloped. They consist of twelve incisors or nippers *
and twelve molars or grinders, six above and six below
of each kind. The dental formula is expressed thus:

Incisors, 3— #; molars, }—$=—24.

According to Veterinary Dentist C. D. House, who
says the care and treatment of foals will affect the
growth of their teeth as much as they will their gen-

* Horsemen call the incisor teeth “ Nippers.” The word ex-
presses the office they perform, to wit, nipping grass, as we!l as
the word “grinder” does in the case of the molars—grinding
corn. They call the first pair of incisors “central nippers,” or
“centrals,” one being on either side of the median line; the
second pair are the “dividers,” for they stand between the first
and third pairs; the third pair are called the “corners,” from
their forming the points of the crescent-lixe figure.

48 THE TEMPORARY DENTITION.

eral development, the foal has no teeth at birth, Na-
ture providing a membrane-like cover for the incisors
as well as the hoofs. In two or three days, however,
the molars are all cut. The incisors are cut in pairs,
two above and two below. The first pair protrude in
from three to eight days, and attain their growth in
about two months. The second pair are cut when the
foal is five or six weeks old. They also attain their
growth inabout two months. The time of cutting the
third pair varies. In some foals they appear as early
as the sixth month; in others as late as the ninth.
They attain their growth in about three months.*

The milk teeth are smaller and whiter and have
more distinct necks than the permanent. Their shin-
ing, milky-white color, M. Chauveau says, is due to
the thinness or absence of the cement, their crowns
being finely striated (not cannular) on the anterior
face, and their growth, unlike the permanent teeth,
ceasing when they begin to be used. t

* M. Rousseau assigns from the seventh to the tenth month
as the period of the completion of the first or colt’s mouth den-
tition. The deciduous incisors have thinner and more trenchant
crowns than the permanent.—Ovwen.

+ The absorption of the roots of the milk teeth by the per-
manent would tend to prevent the continuous growth of the
former; but the real cause appears to be that continuous growth
is contrary to their nature. As the roots are composed of
cement (except the dentine lining the pulp cavity), and as
they are absorbed, it naturally follows that much of the cement
surrounding the crowns of the permanent teeti is derived from
them (cement from cement), thus lessening the drain on the
permanent tooth pulps, which are all the better able to supply
cement for the roots of the permanent teeth. The scarcity of
cement on the crowns of the milk teeth is probably owing to
the fact that they had no cement to absorb. The evil of extract-
ing healthy milk teeth is obvious.

SHED OR ABSORBED. 49

The incisors, which stand in an almost upright
position, are smooth and rounded on the outer sur-
face, but grooved on the inner. Their average length,
including the root, is about an inch, their width
about half an inch. The molars are about an inch
and a quarter in length, and nearly an inch in long
(antero-posterior) diameter. The short (transverse)
diameter of the upper molars, which is about three-
fourths of an inch, exceeds that of the lower nearly a
half. Surgeon John Hughes says that in proportion
to their length the breadth* of the temporary teeth is
greater than the permanent. When first cut the in-
cisor teeth are very sharp; the outer edges are higher
than the inner, the slant resembling that of a chisel.
A little wear, however, dulls the teeth, and brings the
edges toa common level. The contrast between the
edges of the corner incisors, however, is distinct for
some time, the outer edge wearing off slowly.

There is a marked contrast in the appearance of the
incisors at the age of one year and about the close of
the second. At the former period they look new and
fresh, standing close together, while at the latter they
not only look old and worn, but the development of
the jaws has caused them to stand apart. ‘Their nar-
row necks are also conspicuous at two years of age.

The incisors are shed in the order in which they are
cut. Nature provides them as they are needed, and
takes them away so as to cause the least inconvenience
to the foal. During the shedding of the central inci-
sors foals have the use of the dividers and corners.
The permanent centrals are ready for use before the
dividers are shed, and the permanent dividers are

*« Breadth is ‘antero-posterior diameter; thickness is trans-
verse diameter.’”—R. Owen

3

50 THE TEMPORARY DENTITION.

ready before the corners are shed. However, during
the shedding periods, particularly that of the central
teeth, foals experience more or less difficulty in graz-
ing; but if they are given a moderate quantity of soft,
green food, their health will not be impaired, nor will
they lose much flesh.

The central incisors are shed when the foal is about
two. years and a half old, the dividers at three and
a half or four, and the corners at four and a half or
five.

The molars, which Prof. Richard Owen says sqoner
begin to develop roots than the permanent, are shed
with even less inconvenience to the foal than the in-
cisors. The fourth grinder, the first permanent tooth
cut, is ready for use before the first temporary molar
is shed, and the fifth and sixth are ready before the
second and third are shed. ‘The time of shedding the
twelve teeth varies somewhat, and the falling off of
the “caps” of the uppers will precede those of the
lower teeth several weeks. The caps are all that is
left of the temporary molars, their roots and perhaps
a small part of their bodies having been absorbed by
the permanent. In most cases fully four-fifths of
the crowns are worn off by attrition. Thus, when
Nature is let alone, the temporary teeth are absorbed
rather than shed; but when a shell is loose and in the
way, it does no harm to remove it. The first molar is
shed about the end of the second year, the second
about the end of the third, and the third about the
end of the fourth.

Surgeon W. A. Cherry says that the shedding of the
teeth usually occurs in the Spring. There is, he says,
a sufficient interval of time between the shedding of
the upper and lower molars for the new teeth in the

UNFUNCTIONALLY DEVELOPED CANINES. 51

upper jaw to meet the old ones in the lower; sometimes
the respective teeth, when the caps fall off, are not more
than the sixteenth of an inch apart. He also says that
as the temporary teeth wear down they become less
and less dense. :

While, as before said, it does no harm to remove
loose shells, the punching out of a pair of incisors,
which is sometimes done for the purpose of deception,
frequently causes serious injury to the permanent
pair (which should absorb the temporary, and fill the
space that has become too large for it), not to mention
the interference with grazing. The temporary teeth are
often broken off at the neck and the sockets injured;
this sometimes causes the permanent to grow irregu-
larly, which in the case of the horse is a very serious
matter, for if the permanent teeth do not meet, and are
consequently not worn off by attrition, their growth,
which continues throughout life, will cause trouble.
There are cases, however, such as abnormal growths,
accidents, &c., in which it is necessary to remove the
temporary tooth, but the forceps only should be used.
When the teeth have been removed for the purpose of
deception, the object is to make it appear that they
have been shed, and that the animal is older than it
really is.

Veterinary authors, asa rule, do not mention the
temporary tushes. A few odontologists, however, have
described them. Prof. Owen (“ Odontography,” vol. i,
p. 580) says “the small deciduous canine” is cut about
the sixth month, at the time the third or corner inci-
sors are cut. The lower tush, owing to its diminutive
size, and its being so close to the incisor, “is shed
almost as soo as the crown of the contiguous incisor
is in full place, being carried out by the same move-

52 THE TEMPORARY DENTITION.

ment.” Bojanus,* Prof. Owen says, first “drew the
attention of. veteriary authors to it by his memoir
‘De Dentibus Caninis Caducis, &c. Bojanus never
found the lower deciduous canine retained beyond the
first year. The deciduous canine of the upper jaw,
being developed at a short distance behind the incisors,
is less disturbed by the eruption of the outer incisor,
but is nevertheless shed in the course of the second
year. The deciduous canines appear from Camper’s t
observations to retain their place longer in the zebra
than in the horse.”

Monsieur Lecoq says:

“The canine teeth are not shed, and grow but once.
Some veterinarians, and among them Horthomme and
Rigot, witnessed instances in which they were replaced ;
but the very rare exceptions cannot make us look upon
these teeth as liable to be renewed. We must not,
however, confound with these exceptionable cases the
shedding of a small spicula or point, which, in the
majority of horses, precedes the eruption of the real
tusks.”

Prof. C. 8. Tomes says:

“The milk teeth of all the ungulata are very com-
plete, and are retained late. They resemble the per-
manent teeth in general character, but the canines of
the horse, as might have been expected—their greater
development in the male being a sexual character—are
rudimentary in the milk dentition.”

* «Nova Acta Nat. Curios., tom. xii, part ii, p. 697. 1825.”
+‘ Giuvres de Pierre Camper. Paris, 1805.”

Choate ren TPT,

THE PERMANENT DENTITION.

Distinction between Premolars and Molars.—The Bow-like [n-
cisors.—Contrasts between the Upper and Lower Grinders,
and the Rows formed by taem.—The Incisors saved from
Friction.—Horses’ Teeth compared with those of other An-
imals.—Measurements.—Time’s Changes.—Growth during
Life.

THE Permanent Teeth, owing to their increased size
and number, are as well adapted to the needs of the
horse as the temporary are to the foal. In the males
forty teeth are functionally developed ;* in the females
thirty-six, the latter, as a rule, having no canine teeth.
However, their rudiments exist in the jaws, and some-
times, especially in old age, protrude. Of the forty
teeth in the male horse there are twelve incisors, four
canines or tushes (also called cannon or bridle teeth),
twelve premolars,t and twelve molars. The dental
formula is expressed thus:

I.,3—4; C.,4—4; P.M, $4; M, $-9—40.

* The teeth that are not functionally developed are treated of
in the chapter entitled ‘‘ Remnant Teeth.”

+“ Premolars are teeth in front of the molars; they usually
differ from them by being smaller and more simple in form, and
in most animals have displaced deciduous predecessors. But
they are not always smaller nor simpler in form (e. g., the

54 THE PERMANENT DENTITION.

The incisors and premolars absorb and replace the
entire temporary dentition, except the shells or caps
describéd in the preceding chapter, but the canines
and molars are cut through the gums.

In veterinary works, as a rule, no distinction is made
between a premolar and a molar, the twenty-four back
teeth being called either molars or grinders. Prof.
C. S. Tomes says the premolars and molars “ are very
similar to one another in shape, size, and in the pat-
tern of their grinding surface.” There is a difference,
however, between the respective teeth, and naturalists
make a distinction. The premolars (the three first
back teeth), which replace the temporary molars, are
slightly larger than the molars (the three last back
teeth). They have besides a backward inclination,
while the molars incline forward ; the respective teeth
are thus set foward one another. Both kinds are
properly called grinders.

The permanent teeth are cut in pairs, two in either
jaw, the upper teeth preceding the lower from one to
two weeks. In the cutting of the canines, however,
the reverse is the rule, for the lower teeth precede the
upper. About a year’s time elapses between the cut-
ting of the respective pairs of teeth ; that is, when the
central incisors are cut, it will be about a year before
the dividers will emerge. The rule is applicable to
the premolars and molars also, but the case is different,
for twenty-four of these teeth have to be cut during

horse); nor do they always displace deciduous predecessors
(e. g., they do not all do so in the marsupials) ; so that this defi-
nition is not absolutely precise. Still, as a matter of practice,
it is usually easy to distinguish the premolars, and the division
into premolars and molars is useful.”—C. S, Tomes, “Dental
Anatomy,” &¢., p. 258. )

TIME OF CUTTING. . 55

the same period of time that the twelve incisors are
eut. A permanent tooth attains its growth in about a
year.

According to the best authorities, the molar and
canine teeth are cut at the following periods: The
first molars (in veterinary works they are called the
fourth, because the three premolars come in front of
them) are the first permanent teeth cut. The time of
their cutting varies, for the foal’s jaws must be suffi-
ciently developed to afford them room, notwithstand-
ing they are usually the smallest of the six back teeth.
They are cut about the beginning of the second year,
and are generally ready for use by the time the foal is
two years old. The second molars are cut at about
the age of two years, and are therefore fully developed
by the end of the third year. The third pairs, the last
of the molars, and consequently the most posterior of
all the teeth, are sometimes cut as early as the third
year, in which case they would be developed by the end
of the third or the beginning of the fourth year. The
time, however, may be prolonged six months or more.
The canine teeth (tushes) emerge at or near the be-
ginning of the fourth vear.*

The time of the appearance of the incisors and pre-
molars has already been indicated in the preceding
chapter. However, the following extract from Prof.
Owen’s “ Odontography” is appropriate in this place,
as it throws further light on the subject, and to some
extent agrees with the dates already given:

“The first true permanent molar appears between
the eleventh and thirteenth months. The second fol-

* For further particulars concerning the tushes the reader is
referred to the succeeding chapter.

56 THE PERMANENT DENTITION.

lows between the fourteenth and twentieth months.
The crowns of the premolars and the last true molar
are now advancing in the closed sockets of reserve.
The first premolar displaces the second,* and usually
at the same time the very small deciduous molar, at
from two years to two years and a half old. The first
permanent incisor rises above the gui between two
years and a half and three years. At the same period
the second premolar pushes out the third deciduous
molar. The last premolar displaces the last deciduous
molar about the completion of the fourth year, and
the appearance above the gum of the last true molar
is usually anterior to this. The second incisor pushes
out its predecessor between three and a half and four
years. The small persistent canine or tusk, contrary
to the usual rule, next follows, its development having
received no check by the retention of its rudimental
predecessor. Its appearance indicates the age of four
years; but it sometimes appears earlier, rarely later.
The third incisor pushes out the deciduous one about
the fifth year, but is seldom completely in place before
the horse is five years and a half old. The third pre-
molars are then usually on a level with the other
grinders.”

On the completion of the fifth year a male foal is
called a horse, a female or filly foala mare. The teeth,
however, are not all fully developed before the sixth
year, and the roots of the grinders do not begin to

*To prevent confusion, it should be understood that Prof.
Owen calls the “very small deciduous molar” here referred to
the first deciduous molar, notwithstanding it is not functionally
developed. Hence, as it has no successor, the first premolar dis-
places the second d:ciduous molar, the second premolar the third
deciduous molar, and the third the fourth.

THE INCISORS ADAPTED FOR GRAZING. 57

grow till about the seventh year, being, to use Prof.
Owen’s words, “implanted in the socket by an undi-
vided base.”

The incisor teeth, which will average about two
inches and a quarter in length, are characterized by
distinct curvatures, the outer sur-
face, according to Surgeon John
Hughes, forming a third of a cir-
cle, the inner a fifth. Were a string
drawn from the crown of one of
these teeth to the apex of the
root, the figure would resemble a
bow. The upper tecth are larger
than the lower, and there is a dif.
ference in size of the respective
teeth in both jaws, the centrals
being larger than the dividers,
and the dividers larger than the
corners.

The incisors meet edge to edge,
being thus admirably adapted for
the purposes of grazing, and at aaciisa ean
the age of six years the bodies are — ‘tir face.—chawveau.
nearly perpendicular one to the other. They form
nearly semicircular figures, and, when the mouth is
closed, present a rounded outer surface.

“The incisors,” says Prof. Owen, “if found detached,
recent or fossil, are distinguishable from those of the
ruminants by their greater curvature, and from those
of all other anima's by the fold of enamel which pen-
etrates the body of the crown, from its broad, flat sum-
mit, like the inverted finger of a glove.”

The fold of enamel, which is commonly called the
“mark,” but which is also known as the infundibulum,

58 THE PERMANENT DENTITION.

central enamel, &c., according to Surgeon J. Hughes’s
measurements, penetrates the lower centrals to the
depth of from to 74 of an inch; the divid- _
ers from ;, to 4, and the corners from 4 to *
3. It penetrates the upper centrals from 1
inch and +4; to 1 and 4; the dividers from
1 and 4 to 1 and 4, and the corners from 4
to nearly 1 inch. Prof. Youatt says the
grinders have each two infundibula, which
penetrate to their roots.

The following is Prof. A. Chauveau’s description of
the incisor teeth (“The Comparative Anatomy of the
Domesticated Animals,” Fleming’s trans., p. 349):

“The general form of the incisors is that of a tri-
faced pyramid, presenting an incurvation whose con-
cavity is toward the mouth. The base of this pyra-
mid, the crown of the tooth, is flattened before and
behind. The summit or extremity of the fang, is, on
the contrary, depressed on both sides. The shaft of
the pyramid presents at different points of its hight, a
series of intermediate conformations, which are utilized
as indications of age, the continual growth of the teeth
bringing each of them in succession to the frictional
surface of the crown.

“Examined in a young tooth, but one that has com-
pleted its evolution, the free portion presents the fol-
lowing characteristics: An anterior face, indented by
a slight longitudinal groove, which is prolonged to
the root ; a posterior face, rounded from side to side;
two borders, of which the internal is always thicker
than the external; and, lastly, the surface of friction.
The latter does not exist in a tooth that has not been
used, but in its stead are two sharp margins, circum-

THE TWO RINGS OF ENAMEL. 59

scribing a cavity named the external dental cavity, or,
better, infundibulum. This cavity terminates by a
conical cv-de-sac, which descends more or less deeply
*into the substance of the tooth. The margins are
designated the anterior and posterior. ‘The latter, less
elevated than the former, is cut by one or more
notches, which are always deepest in the corner teeth.
It is by the wear of these margins that the surface of
friction is formed, and in the center of which the in-
fundibulum persists during a certain period of time.

“The root is perforated by a single aperture, through
which the pulp of the tooth penetrates into the inter-
nal cavity.

“In the composition of the incisor teeth are found
the three fundamental substances of the dental organ.
The dentine envelops the pulp cavity. Dentine is de-
posited in this cavity after the complete evolution of
the tooth to replace the atrophied pulp, the yellow tint
of which distinguishes it from the dentine of the first
formation. It forms on the table of the tooth the
mark designated by Girard the dentinal star.

“The enamel covers the dentine, not only on its free
portion, but also on the roots; it does not extend,
however, to their extremities. It is doubled into the
external dental cavity, lining it throughout; and when
the surface of friction is established, a ring of enamel
may be seen surrounding it, and an internal ring cir-
cumscribing the infundibulum. The first circle is
called the encircling enamel, the second the central
enamel. In the virgin tooth the central enamel is
continuous with the external enamel, and passes over
the border which circumscribes the entrance to the
infundibulum,

“The cement is applied over the enamel like a pro-

60 THE PERMANENT DENTITION.

tecting varnish, but is not everywhere of the same
thickness. On the salient portions it is extremely
thin, and the friction caused by the food, the lips, and
the tongue soon wears it away altogether. It is more
abundant in depressed situations, as in the longitudi-
nal groove on the anterior face of the tooth, and par-
ticularly at the bottom of the infundibulum. The
quantity accumulated in this cul-de-sac is not, how-
ever, always the same. We have seen it almost null,
and on the other hand, we possess an incisor unworn,
or nearly so, in which the cavity is almost entirely
obstructed by it. We are not aware that, up to the
present time, any account has been taken of these dif-
ferences in calculating the progress of wear; but it is
manifest that they shorten or prolong the time re-
quired for the effacement of the infundibulum.”

The grinder teeth, the horse’s millstones, present
various and interesting contrasts. They are sepa-
rated from the incisors by -a space that will average
about four inches in extent, the sharp-pointed tushes
(in males) only intervening. The space between the
grinders and tushes is called the diastema (place for
the bit). The upper grinders, except the first and
last, are nearly quadrangular in form. The first and
last, which exceed the others about a third of an inch
in antero-posterior (front to rear) diameter, terminate
in obtuse angles, which are far more pronounced on
the inner than on the outer surface, thus affording the
tongue fuller and freer play, without the danger of its
being lacerated, as would be the case were the angles
sharp. The form of the lower grinders, with the same
exceptions in the case of the first and last, is nearly
rectangular; their antero-posterior diameter is the

THE HORSE’S DINNER TABLES. 61

same as that of the upper teeth, but their transverse
diameter is nearly a half less.

The broad crowns of the upper teeth form what are
ealled by veterinarians “ tables,’ whereon the food is
ground or kneaded by the narrow-crowned opposite
grinders, the lateral movement of the lower jaw ena-
bling the latter teeth to pass over the entire extent of
the former.

The crown surfaces of the upper and lower rows are
slanting instead of level, the former slanting inward,
the latter outward. The inclined-planes are thus in
perfeet opposition, and yet in perfect harmony, for they
facilitate the lateral and semicircular movement of the
lower jaw during mastication.

The figures formed by the upper and lower rows of
grinders, aside from the difference in their thickness,
are very dissimilar. The upper rows are slightly con-
cave, and converge in conformity to the narrowing of
the jaws; the space between the sixth grinders averages
about two inches and four-fifths, while that between
the first is about two inches. The lower rows form
regular but oblique lines, which also converge, like the
sides of a hopper, in conformity to the narrowing of
the jaws, the space between the two sixth grinders and
the two first averaging respectively two inches and a
half and one inch and a half. Thus, when the mouth
is closed, the lower teeth in the region of the sixth
grinders scarcely cover a third of the crown surface of
the upper teeth, while those in the region of the first
barely lap their inner edges. This apparent structural
defect is overcome by the lateral movement of the
lower jaw, which, owing to the fact that it increases
in proportion to the distance from its hinge-like joint
in the region of the temporal bone and zygomatic

62 THE PERMANENT DENTITION.

arch,* is greater in the region of the first grinders
than in that of the sixth. Therefore it will be per-
ceived that it is only alternately that the rows are used
in the performance of the masticatory function, and
that were the grinders in exact apposition (edge to
edge), the lateral and semicircular movement of the
lower jaw would be as awkward and unnatural in the
case of the horse as the same movement would bein a
human being.

There are still other contrasts between the grinders.
According to Surgeons M. H. Bouley and P. B. Fergu-
son, the upper teeth are slightly convex, the lower
slightly concave. Again, according to Charles D.
House, the outer surface of the upper grinders is pro-
vided with a coat of enamel twice as thick as that of
the inner, while the reverse is the case with the lower
teeth. There is design in this provision of Nature
(notwithstanding Mr, House says it is inexplicable),
for the projecting edges receive that which they re-
quire, to wit, strength in proportion to their hight;
otherwise they would be easily broken off. As the

* Prof. Youatt says: “The branches of the lower jaw termi-
nate in two processes, the coracoid (beak-like), and the condy-
loid (rounded). The coracoid passes under the zygomatic arch,
the temporal muscle being inserted into it and wrapped round
it. The condyloid is received into the glenoid (shallow) cavity
of the temporal bone, at the base of the zygomatic arch, and
forms the joint on which the lower jaw moves. The joint ad-
mits of a hinge-like motion, which is the action of the jaw in
nipping the herbage and seizing the corn. The corn, however,
must be ground; bruising and champing it are not sufficient for
the purposes of digestion. It must be putintoa mill. Itds put
into a mill, and as perfect a one as imagination can conceive.
The construction of the glenoid cavity gives the required lateral
or grinding motion.”

THE GRINDERS THEIR OWN WHETSTONES. 63

lower edges have only about half the hight of the up-
_ per, they do not require more than half the quantity
of enamel to strengthen them. Another use of this
unequal disposition of enamel is its tendency, by its
wear, to preserve the slant of the respective crown sur-
faces. Further, the dentine, which fills the interspaces
between the folds or ridges of enamel, being softer
than the enamel, wears out faster, thus keeping the
ridges sharp.* The grinders are therefore, owing to
this “interblending of the dental tissues,” their own
whetstones as well as the horse’s millstones.

Some writers, even of the present day, deny that the
enamel penetrates to the interior of the grinders; but
the fact that it does was established by John Hunter
over a century ago, and a cut of a section of a horse’s
grinder (slightly magnified) showing the enamel folds,

* Prof, R. Owen illustrates the above principle in the Intro-
duction to his “Odontography,” page 26. He says: “It (the
enamel) sometimes forms only a partial investment of the crown,
as in the molar teeth of the iguanodon, the canine teeth of the
hog and hippopotamus, and the incisors of the Rodentia. In
these the enamel is placed only on the front of the tooth, but is
continued along a great part of the invested base, which is never
contracted into one or divided into more roots, SO that the char-
acter of the crown of the tooth is maintained throughout its
extent as regards both its shape and structure. The partial
application of the enamel operates in maintaining a sharp edge
upon the exposed and worn end of the tooth precisely as the
hard stecl keeps up the outer cutting edge of the chisel by being
welded against an inner plate of softer iron.”

Prof. C. §. Tomes, speaking of the grinder teeth of the horse,
says : ‘As each ridge and pillar of the tooth consists of dentine
bordered by enamel, and the arrangement of the ridges and pil-
lars is complex, and as, moreover, cementum fills up the inter-
spaces, it is obvious that an efficient rough grinding surface will
be preserved by the unequal wear of the several tissues.”

64 THE PERMANENT DENTITION.

may be found in his “ Natural History of the Human
Teeth.”

The formation of the enamel is thus described by
Prof. Bouley and Surgeon Ferguson (‘ Veterinarian,”
1844):

“Tn the grinder teeth the enamel may be said to
resemble a little ribbon, which forms, in refolding
many times upon itself in the interior of the tooth, a
succession of undulating planes, and constitutes the
hard external envelop of the cubic mass of the organ.
An idea of this disposition may be formed on examin-
ing a tooth which is not yet cut, but which is ready to
be cut. Those that have been worn, present on their
crowns, besides the undulating lines of the enamel
envelop, a succession of reliefs, salient and sinuous, of
the substance of the enamel, which are nothing else
than the free borders of, this folded ribbon. It is in
the intervals of the folds of enamel that is deposited
the ivory-colored substance (dentine), which renders
the tooth a solid mass when it has attained its full
growth.”

Prof. Richard Owen, one of the first odontologists
of the age, in whose numerous works descriptions of
many kinds of teeth may be found, has paid a fair
share of attention to the study of horses’ teeth, both
recent and fossil. His description of the grinders and
comparisons with the teeth of cther animals are too
interesting to be omitted here, and render any apology
for the few repetitions of facts already given unneces-
sary. He says (“ Odontography,” vol. 1, p. 572):

“The horse will yield us the first example of the
dentition of the hoofed quadrupeds with toes in un-

ANOPLOTHERES, RUMINANTS, AND TAPIRS. 65

even number, because it offers in this part of its organ-
ization some transitional features between the dental
characters of the typical members of the isodactyle
and of those of the anisodactyle ungulata.

“ All the kinds of teeth are retained and in almost
normal numbers in both jaws, with as little unequal
or excessive development as in the anoplothere,* but
the prolongation of the slender jaws carries the canines
and incisors to some distance from the grinders, and cre-
ates a long diastema, as in the ruminants f¢ and tapirs.{

*<«<The anoplothere was one of the earliest forms of hoofed
quadrupeds introduced upon the surface of this earth, and it is
characterized by the mast complete system of dentition. It not
only possessed incisors and eanines in both jaws, but they were
so equally developed that they formed one unbroken series with
the premolars and molars, which character is now found only
in the human species. The dental formula is: I., 8—3,3—3;
C.,1—1,1—1; P. M.,4—4, 4—4; M., 3—3,3—3=44. The An-
oplothere Commune was the size of an ass, and, with the other
species of the extinct genus, had a cloven hoof, like the Rumi-
nants, but the division extended through the metacarpus and
metatarsus. The anoplothere was an animal of aquatic habits,
and had a very long and strong tail, which Cuvier ecnjectures
to have been used like that of the otter in swimming.”—Ovwen.

+ “The ordinary dental formula of the Ruminantia is: I.
(upper jaw), 0—0, (lower jaw), 3—3; C.,0—0, 1-1; P.M., 8—3,
3—3; M., 8—3, 3—3=382. The antelopes, the sheep, and the
ox, which are collectively designated the ‘ hollow-herned ’ rumi-
nants, present this formula. It likewise characterizes many of
the ‘solid-horned’ ruminants, or the deer tribe, the exceptions
having canine teeth in the upper jaw in the male sex, and some-
times also in the female, though they are always smaller in the
latter.” —Owen.

{ “ The dental formula of the tapiris: L, 3-—3,.3—3; C.,1—1,
1—1; P. M., 4—3, 4-3; M., 3—3, 3—3=42.”—Owen.

It is noteworthy that the dentition of the tapir corresponds
precisely in number with that of the horse, provided the latter’s

66 THE PERMANENT DENTITION.

“The upper grinder teeth present a modification of
the complex structure intermediate between the ano-
plotherian and ruminant patterns. The crown is
cubical, but is impressed on the outer surface by two
wide and deep longitudinal channels. It is penetrated
from within by a valley, which enters obliquely from
behind forward. This is crossed by two crescentic
valleys, which soon become insulated, as in the camel ;*
but a large internal lobe, at the end of the oblique val-
ley, presents more of the anoplotherian proportions
than is shown by any ruminant. It is at first distinct;
but although it soon becomes confluent with the ante-
rior lobe in the existing species of the horse, it con-
tinued distinct much longer, and with more of the con-
ical or columnar form, in the primigenial horse of the
miocene tertiary period.

“The grinder teeth of the horse, Cuvier + remarks,

Remnant teeth are counted ; and, besides, the odd teeth in both
animals appear in the wpper jaw. Prof. T. H. Huxley says:
“Deepen the valley, increase the curvature of the (outer) wall
and lam’inz (transverse ridges); give the latter a more directly
backward slope; cause them to develop accessory ridges and
pillars, and the upper molars of the tapir will pass through the
structure of that of the rhinoceros to that of the horse.”

*< The dental formula of the camel is: I.,1—3,1—3; M.,
6—6, 6—6—32. The anterior molars are conical. They are
separated from the posterior molars, and are sometimes regarded
as canines. The upper incisors are also conical, compressed,
somewhat curved, resembling canines, and are used for tearing
up the hard and strong plants of the desert, on which the ani-
mal usually feeds.” — American Cyclopedia.

+ A French naturalist. Died May 13, 1882. ‘‘ He is regarded
as the founder of the science of comparative anatomy, and his
knowledge of the science was such that a bone or a small frag-
ment of a fossil animal enabled him to determine the order, and

THE HORSE AND THE RHINOCEROS. 67

have a closer analogy with those of the rhinoceros *
than might at first be supposed. The anterior cres-
centic enamel represents the termination of the prin-
cipal or oblique valley, which is cut off by a bridge of
dentine analogous to that in the leptorhine rhinoceros.
The posterior crescentic island is a further develop-
ment of the folds in the rhinoceros’ molar, but is much
earlier insulated in the horse.

“Tn the lower jaw the same analogies may be traced.
The teeth, on the outer side, are divided into two
convex lobes by a median longitudinal fissure; on the
inner side they present three principal unequal convex
ridges, and an anterior and posterior narrower ridge.
The crown of the grinder is penetrated from the inner
side by deeper and more complex folds than in the
anoplothere, and still more so than in the rhinoceros

even genus, to which it belonged. The time of Cuvier marks
the opening of a new epoch in comparative anatomy. He ap-
plied this science to natural history, physiology, and to the study
of fossils The first edition of “Lecons d’Anatomie Comparée”
appeared about the beginning of the present century, and the
second was the last work upon which Cuvier labored. For
more than thirty years he had collected an immense amount of
facts and materials, which are partly embodied in this book. It
is a monument of patient industry, a model in arrangement, and ‘
a mine of knowledge, of which all observers since have availed
themselves.” — American Cyclopedia.

*« The essential characteristics of the dentition of the genus
rhinoceros are to be found in the form and structure of the
molar teeth. They differ essentially from those of the horse by
being implanted by distinct roots. The normal dental formula
of the molar series is: P. M., 4—4, 4—4; M., 8—3, 3—3=28.
There are no canines. As to the incisors, the species vary, not
only in regard to their form and proportions, but also their ex-
istence.”—Owen.

68 THE PERMANENT DENTITION.

and paleothere.* The anterior valley between the nar-
row ridge and the first principal internal column ex-
pands into a suberescentic fold. The second is a short,
simple fold, and terminates opposite that which pene-
trates the tooth from the outer side. The third inner
fold expands in the posterior lobe of the tooth hke the
first, and two short folds partially detach a small ac-
cessory lobe at the posterior part of the crown. All
the valleys, fissures, or folds, in both the upper and the
lower grinders, are lined by enamel, which also coats
the whole exterior surface of the crown.

“The character by which horses’ grinders may best
be distinguished from the teeth of other herbivora cor-
responding with them in size, is the great length of
the tooth before it divides into roots. This division,
indeed, does not begin to take place until much of
the crown has been worn away. Thus, except in old
horses, a considerable proportion of the whole of the
tooth is implanted in the socket by an undivided base.
This is slightly curved in the upper grinders.

“The deciduous molars have shorter bodies than the
permanent, and sooner begin to develop roots. They
may be distinguished from the rooted molar of a rumi-
nant, as may also their permanent successors with
roots, by their form and the pattern of their grinding
surface. The latter may be a little changed by the
partial obliteration of its enamel folds, but it gen-
erally retains enough of its character to show the
distinction.”

*« The species of paleotherium, which appear to have accom-
panied the anoplotheres in the first introduction of hoofed quad-
rupeds upon this planet, were characterized by the same com-
plete dental formula, namely, forty-four functionally ios
teeth.”— Owen.

ARISTOTLE’S MISTAKE. 69

Monsieur Lecoq’s description of the grinder teeth,
like the one just quoted, is a contribution to dental
science. The repetition of facts already given is off-
set by its additional facts, and its historical informa-
tion is as interesting as are Prof. Owen’s comparisons.
It is as follows (“ Traité de l’Exterieur du Cheval et des
Principaux Animaux Domestiques”) :

“Tt was believed for a long time that the grinders of
Solipeds were all persistent teeth. This error, founded
on the authority of Aristotle, was so deeply rooted that,
although Ruini, toward the end of the Sixteenth cen-
tury, had discovered the existence of two temporary
molars, Bourgelat did not believe it when he founded
the French veterinary schools, and was only convinced
when Tenon proved by specimens, in 1770, that the
first three are deciduous.

“ Generally considered, the grinder arcades have not
the same disposition in both jaws. Wider apart in the
superior one, they form a slight curve, whose convexity
is outward. In the inferior jaw, on the contrary, the
two arcades separate in the form of a V toward the back
of the mouth. Instead of coming in contact by level
surfaces, the grinders meet by inclined-planes. In the
lower jaw the internal border is higher than the exter-
nal, while the reverse is the rule in the upper. This
circumstance prevents the lateral movement of the
lower-jaw taking place without separation of the inci-
sors, and thus saves them from friction.

“ Like the incisors, each grinder presents for study
a free and a fixed portion. The free portion (the body),
nearly square in the upper grinders, broader than
thick in thé lower, shows at the external surface of the
former two longitudinal grooves, the anterior of which

70 THE PERMANENT DENTITION.

is the deeper, both being continued on the incased
portion. This is not the case with the lower grinders,
which have but one narrow and frequently indistinet
groove. ‘The internal surface, in both jaws, presents
only one groove, and that but little marked. It is
placed backward in the upper teeth, and is most ap-
parent toward the root. The anterior and posterior
faces of the respective teeth, which are in contact with
each other, are nearly level, but at the extremities of
the arcades the isolated faces are converted into a nar-
row border.

“The grinders are separated from each other by their
imbedded portion, particularly at the extremities of
the arcades, an arrangement which strengthens them
by throwing the strain put upon the terminal teeth
toward the middle of the line. They exhibit a variety
of roots. In the first and last, either above or below,
there are three, while the intermediate teeth have four
in the upper jaw, and only two in the lower. The
root, if examined a short time after the eruption of
the free portion, looks only like the shaft of the latter,
without fangs,* but a wide internal cavity. The roots
form when the teeth begin to be pushed from their
sockets ; they cease to grow as soon as their cavities
are filled with new dentine, but the tooth, constantly
growing, causes the walls inclosing it to contract; so
that in extreme age the shaft, basnpletcly worn away,
leaves several stumps formed by tie roots.

“'The replacement of the twelve molars is not at all
like what happens with the incisors. They grow im-

* Fang for root is obsolete. Fang signifies crown—especially
the pointed teeth of animals of prey and the poison-fang of ser-
pents. Fang for both root and crown causes confusion.

RELATIVE SIZE OF THE GRINDERS. ve §

mediately below the temporary teeth, and divide their
two roots into four, the absorbing process continuing
until the bodies are reduced to simple plates and fall
off”

In measuring the teeth in a large-sized head the
following facets and figures were elicited: Length of
grinder rows, 7 inches. Space between the sixth
grinders, upper rows, measuring from the inner sur-
faces, but not including the angles, 3 inches; center of
rows, 213; first grinders, not including the space of
the angles, 274. Lower rows: Between the sixth
grinders, 24; center of rows, 14%; first grinders, 13.
Upper tush from first grinder, 24; from third incisor,
13. Lower tush from grinder, 34; from incisor, %.
Space between the upper tushes, 2; between the lower,
13. Space between the upper corner incisors, measur-
ing from center of teeth, 2; lower, 14%; between the
upper dividers, 14; lower, 13. Distance around semi-
circle of upper incisors, 444; around lower, 344.

As a supplement to the above, the following extract
is made from “An Essay on the Teeth” by Surgeon
John Hughes (“ Veterinarian,’ 1841, “ Proceedings
Vet. Med. Ass.,” p. 22):

“The upper and lower grinders will measure from
24 to 3 inches in length. In transverse diameter the
former exceed the latter in the proportion of 7 to 4.
The aggregate measurement of the sockets of the up-
per grinders is about 7 inches. The first tooth occu-
pies one inch and a half of this space, the second 14,
the third 14, the fourth 1, the fifth 1, and the sixth 14.
The breadth of the corresponding lower teeth is about
the same as that of the upper.”

"2 THE PERMANENT DENTITION.

There is a difference in the structure of all the teeth,
and an efpert can tell to which socket each belongs.
They fit their sockets accurately,* are braced all round
by the jawbone processes, and receive besides support

aad protection from the gums, which adhere to them _

tenaciously and are almost as hard as cartilage. Use
and time, however, work changes, the teeth all wearing
down, the incisors in particular changing shape and
projecting outward. At the age of twelve years the
gums begin to slacken, causing the teeth to look
longer. ‘The change from the upright position of the
incisors, and the increased space between them and
the canines, is caused by the elongation of the jaws,
which carries the incisors outward. The canines do
not change their position, but they become mere stubs.

*«The manner of attachment of the human teeth is that
termed ‘ gomphosis,’ 7. €., an attachment comparable to the fit-
ting of a peg into a hole. The bony sockets, however, allow of
a considerable degree of motion, as may be seen by examining
the teeth in a dried skull, the fitting being in the fresh state
completed by the interposition of the dense periosteum of the
socket. This latter, by its elasticity, allows of a small degree
of motion in the tooth, and so doubtless diminishes the shock
which would be occasioned by mastication were the teeth per-
fectly immovable and without a yielding lining within their
sockets.” —C. S. Tomes, “Dental Anatomy,” &e, p. 23.

John Hunter says (“Human Teeth”): “The roots of the
teeth are fixed in the gum and alveolar processes by that species
of articulation called gomphosis, which in some measure resem-
bles a nail driven into a piece of wood. ‘They are not, however,
firmly united with the processes, for every tooth has some de-
gree of motion; and in heads which have been boiled cr macer-
ated in water, so as to destroy the periosteum and adhesion of
the teeth, we find them so loosely connected with their sockets
that the incisors are ready to drop out, the grinders remaining,
as it were, hooked, from the number and shape of their roots.”

ae

THE HORSE AS A MILLER. 13

Notwithstanding all these changes it is a rare thing to
see a missing incisor‘or grinder. The canines, how-
ever, owing perhaps to their sharp points, not only
wear out, but now and then, in extreme old age, fall
out.

The permanent teeth agree with the temporary in
but few respects, though the general appearance of the
respective teeth is nearly the same. They differ in
many respects. Their bodies are larger and denser,
and their roots longer and stronger. ‘The grooving of
the incisors is the reverse; the outer surface is usually
double grooved, the inner smooth, both being slightly
rounded. ‘They are less upright in position, and less
sharp, but are more discolored, and the “marks” (in-
fundibula) are wider and deeper and wear out more
slowly. ‘They attain their growth more slowly, and a
healthy tooth continues to grow throughout life.

In proof of the last assertion many authorities could
be cited, but those that follow must suffice. It is a
wise provision of Nature, as but for it a horse’s teeth,
particularly the grinders, would be worn to stubs in
two or three years after their development. Prof.
M. H. Bouley and Surgeon P. B. Ferguson say (“ Vet-
erinarian,” 1844) :

“The growth throughout life is a compensation for
the enormous wear of the teeth, the horse having to
perform for himself that which the miller performs for
man; and thus during a very long time the teeth pre-
serve, if not their form, at least their length.”

Prof. A. Chauyeau, referring to the horse, says:

“The permanent tecth present in their development
a common but very remarkable characteristic, rarely
4

94 THE PERMANENT DENTITION.

met with in other animals. They are thrust up from
the alveoli during the entire life of the animal to re-
place the surface worn by friction.”

The activity of the growth of the grinders is re-
markable about the seventh year, for at this time
their roots begin to develop; growth is thus going on
at both ends at the same time. A 4@&
third movement is now at least // eZine
apparent, for the undivided base [lm A
in the socket appears to be slowly BU
pushed out, which may partly ac- FW
count for the shrinkage of the ea
gums. The tenacity of the adhe- Left upper molar.
sion of the periostewm would not wholly prevent this
movement, for it acts as a cushion, its elasticity pre-
venting concussions. The undivided base resembles
a post set in the ground, except that the implanted
part is smaller than the crown.

Up to about the sixteenth year, the growth of the
teeth results chiefly from vitality transmitted through
the medium of the pulp. After the pulp has become
converted into dentine, however, the tooth “ draws its
nourishment from the blood-vessels of the socket.” *

Surgeon Louis Brandt (“ The Age of Horses,” In-
dianola, Texas, 1860) says of the incisors :

‘‘The length of the teeth is constantly decreasing,
and often quite regularly, so that in extreme old age
they will sometimes not exceed half an inch in length,
while at their prime they were 24 to 3 inches long.
Their breadth decreases nearly in proportion to the
decrease in length.”

* See pages 169-70.

CHAPTER IV.
THE CANINE TEETH OR TUSHES.

Practically Useless——Different in their Nature from the other
Teeth.—Were they formerly Weapons of Offense and De-
fense?—Views of Messrs. Darwin, Hunter, Bell, Youatt, and
Winter.—Their time of Cutting the most Critical Period of
the Horse’s Life.

THE Canine Teeth (laniarti dentes), comparatively
speaking, are of little practical use; at least they are
of little use to the modern horse. ‘They have been
much reduced in size during the evolution of the horse,
and, if Mr. C. R. Darwin’s theory is correct, are prob-
ably “in the course of ultimate extinction.” They
distinguish the sex, it is true, but their loss would not
be felt on that account. The horse sometimes uses
them in tearing bark from trees, for he is by instinct
his own (botanical) doctor, and the bark is his medi-
cine. The sharp points of the tushes penetrate the
bark more readily than the incisors, and apparently
the horse wishes to save his incisors, thus showing his
horse-sense. Their nature is different from that of
the other teeth, for the incisors and grinders grow till
old age. This is not the case with the tushes, and,
further, they are never in apposition (superposed), and
consequently do not wear one another.

The lower tushes, as before said, are about three-
fourths of an inch from the corner incisors, and about
three inches and a half from the first grinders. The

"6 THE CANINE TEETH.

space between the upper tushes and the corner incisors
is double that of the lower, and they are consequently
three-fourths of an inch nearer the grinders. The dis-
tances may vary a half an inch or more. ‘The space
between the tushes and grinders is, as already said,
called the diastema.

The average hight of the tushes when full grown is
about three-fourths of an inch. They resemble tri-
angles, having broad bases and sharp crowns, the latter
being remarkable, says Prof. Owen, “for the folding in
of the anterior and posterior margins of enamel, which
here includes an extremely thin layer of dentine.”
They have a slight outward inclination, that of the
lower teeth exceeding that of the upper. Their outer
surface is oval, the inner (in the young horse) being
deeply grooved. As age advances the inner surface
becomes oval also, and the crowns more or less blunt.
The root of a tush, which is longer than its body,
has a distinct backward curvature, rendering the ex-
traction of these teeth almost impossible. The tushes
have no “marks” (infundibula), the nerve cavity ex-
tending through nearly the entire length of the tooth.

Monsieur Lecoq says:

“The free portion of the tusk, slightly curved and
thrown outward, particularly in the lower jaw, presents
two faces (internal and external), separated from one
another by two sharp borders, which incline to the
inner side, and meet in a point at the extremity of the
tooth. The external face, slightly rounded, presents a
series of fine strie, longitudinal and parallel. The
internal has a conical eminence in its middle, whose
point is directed toward that of the tooth, and is sep-
arated from each border by a deep groove.

SIMPLICITY OF THEIR STRUCTURE. 7

“The root of the tusk, more curved than the free
portion, bears internally a cavity analogous to that of
the root of the incisors, and, like it, diminishes in size
and finally disappears as age advances; but it is always
relatively larger, because of the absence of the infun-
dibulum in the canine teeth.

“The structure of these teeth is much simpler than
that of the incisors, consisting, as they do, of a central
mass of dentine, hollowed by the pulp cavity, and coy-
ered by an external layer of enamel, on which is de-
posited a little cement.”

As there is more or less mystery about the tushes,
and as they are important factors in the consideration
of thé problem of the evolution of the horse as well as
other animals, a few extracts from the works of well-
known scientific men, giving their views on the sub-
ject, will prove interesting if not instructive.

Mr. Charles R. Darwin gives the following interest-
ing account of tushes and their uses in certain animals,
among them the horse (“ Descent of Man,” vol. ii, pp.
245-6-7) :

“ Male quadrupeds which are furnished with tusks
use them in various ways, as in the case of horns.
The boar strikes laterally and upward, the musk-deer
with serious effect downward. The walrus, though
having a short neck and unwieldy body, ‘can strike
upward, downward, or sideways with equal dexterity.’
The Indian elephant fights, as I was informed by the
late Dr. Falconer, in a different manner according to
the position and curvature of his tusks. When they
are directed forward and upward, he is able to fling a
tiger to a great distance—it is said to even thirty feet;

78 THE CANINE TEETH.

when they are short and turned downward, he en-
deavors suddenly to pin the tiger to the ground, and
in consequence is dangerous to the rider, who is liable
to be dismounted.

“Very few male quadrupeds possess weapons of two
distinct kinds specially adapted for fighting with rival
males. The male muntjac-deer (Cervulus), however,
offers an exception, as he is provided with horns and
exserted canine teeth. But one form of weapon has
often been replaced in the course of ages by another
form, as we may infer from what follows. With rumi-
nants the development of horns generally stands in an
inverse relation with that of even moderately well-
developed canine teeth. Thus camels, guanacoes,
chevrotains, and musk-deer are hornless, and they
have efficient canines, these teeth being ‘always of
smaller size in the females than in the males.’ Male
deer and antelopes, on the other hand, possess horns,
and they rarely have canine teeth, and these when
present are always of smaller size, so that it is doubt-
ful whether they are of any service in their battles.
With Antelope montana they exist only as rudiments
in the young male, disappearing as he grows old.
Stallions have small canine teeth, but they do not
appear to be used in fighting, for stallions bite with
their incisors, and do not open their mouths widely
like camels and guanacoes. Whenever the adult male
possesses canines now in an inefficient state, while the
female has either none or mere rudiments, we may
conclude that the early male progenitor of the species
was provided with efficient canines, which had been
partially transferred to the females. The reduction of
these teeth in the males seems to have followed from
some change in their manner of fighting, often caused

TUSHES TEN FEET LONG. 79

(but not in the case of the horse) by the development
of new weapons.”

In the first volume of the “Descent of Man,” page
139, Mr. Darwin attributes the reduction in size of the
tushes in horses to their “ habit of fighting with their
incisor teeth and hoofs,” and on page 231, of the sec-
ond volume, he continues the discussion of canines in
different animals as follows:

“In the male dugong the upper incisors form offen-
sive weapons. In the male narwhal one of the upper
teeth is developed into the well-known, spirally-twisted,
so-called horn, which is sometimes from nine to ten
feet long. It is believed that the males use these horns
for fighting together, for ‘an unbroken one can hardly
be got, and occasionally one may be found with the
point of another jammed into the broken place.’ The
tooth on the opposite side of the head in the male con-
sists of a rudiment about ten inches in length, which
is imbedded in the jaw. It is not, however, very un-
common to find double-horned male narwhals in which
both teeth are well developed. In the females both
teeth are rudimentary. The male cach’alot* has a

* “Sperm-whale or cachalot (Physeter macrocephalus). My
friend Mr. Broderip possesses a tooth of a male Physeter, with
the base open and uncontracted, which measures nine inches
and a half in length, nine inches in circumference, and weighs
three pounds. An ingenious whale-fisher has carved the chief
incidents of his exciting and dangerous occupation on one side
of this very fine tooth. The other side bears the following in-
scription: ‘The tooth of a sperm-whale, that was caught by the
ship Adam’s crew, off Albemarle Point, and made 100 bbls. of oil,
in the year 1817.’ Below the inscription are two excellent
figures of the cAchalot, one spouting, the other dead and marked
for flensing.” —Owen’s “Odontography,” Vol. I, pp 353-4.

80 THE CANINE TEETH.

larger head than the female, and it no doubt aids these
animals in their aquatic battles. Lastly, the adult
male ornithorhyn’chus is provided with a remarkable
apparatus, namely, a spur on the foreleg, closely re-
sembling the poison fang of a venomous snake. Its
use is not known, but we may suspect it serves as a
weapon of offense. It is represented by a mere rudi-
ment in the female.” *

The foregoing extracts would not be complete with-
out giving the views of this great disciple of evolution
concerning the same teeth inman. He says (“ Descent
of Man,” vol. 1, p. 198):

“We have thus far endeavored rudely to trace the
genealogy of the vertebrata by the aid of their mutual
affinities. We will now look to man as he exists, and
we shall, I think, be able partially to restore during
successive periods, but not in due order of time, the
structure of our early progenitors. This can be effected
by means of the rudiments which man still retains, by
the characters which occasionally make their appear-
ance in him through reversion,+ and by the aid of the
principles of morphology and embryology.{ The early

* For further information concerning this strange animal see
the ‘‘ Vocabulary.”

+“ The occasional appearance at the present day of canine
teeth which project above the others, with traces of a diastema
or open space for the reception of the opposite canines, is in all
probability a case of reversion to a former state, when the pro-
genitors of man were provided with these weapons.” —‘‘Descent
of Man,” Vol. IL, p. 309.

t “The human em’bryo resembles in various points of struc-
ture certain low forms when adult. For instance, the heart at
first exists as a simple pulsating vessel; the excreta are voided
through a cloacal passage, and the os coccyx projects like a true

walk

=_—=

THE EARLY PROGINITORS OF MAN, 81

progenitors of man were no doubt once covered with
hair, both sexes having beards. ‘Their ears were
pointed and capable of movement, and their bodies
were provided with a tail, having the proper muscles.
Their limbs and bodies were also acted on by muscles
which now only occasionally reappear, but are normally
present in the quadrumana. ‘The great artery and

tail, ‘extending considerably beyond the rudimentary legs.’
The great-toe, as Prof. Owen remarks, ‘which forms the ful-
crum when standing or walking, is perhaps the most character-
istic peculiarity in the human structure; but in an embryo
about an inch in length, Prof. Wyman found that the great-toe
was shorter than the others, and instead of being parallel to
them, ‘ projected at an angle from the side of the foot, thus cor-
responding with the permanent condition of this part in the
quadrumana” * * * When the extremities are developed,
‘the feet of lizards and mammals, the wings and feet of birds,
no less than the hands and feet of man, all arise from the same
fundamental form.’ (Von Baer).”—‘‘Descent of Man,” Vol. I, pp.
LU-16.

“Each human individual is developed from an egg, and this
egg is a simple cell, like that of any animal or plant. The em-
bryo, in the early stages of development, is not at all different
from those of cther animals. At a certain period it has essen-
tially the anatomical structure of a lancelet (the lowest verte-
brate), later of a fish, and in subsequent stages those of am-
phibian and mammal forms. In the further evolution of these
mammal forms, those first appear which stand Jowest in the
series, namely, forms allied to beaked animals (ornithorhyn-
chus); then those allied to pouched animals (marsupials), which
are followed by forms most resembling apes, till at last the
peculiar human form is produced as the final result. Every one
knows that the butterfly proceeds from a pupa, the pupa from a
caterpillar, to which it bears no resemblance, and again the cat-
erpillar from the egg of the butterfly. But few, except those of
the medical profession, are aware that man, in the course of his
individual evolution, passes through a series of transformations

82 THE CANINE TEETH.

nerve of the humerus ran through a supra-condyloid
fora’men. At this or some earlier period the intestine
gave forth a much larger diverticulum or cecum than
that now existing. The foot, judging from the con-
dition of the great-toe in the fetus, was then prehen-
sile, and our early progenitors were no doubt arboreal
in their habits, frequenting some warm, forest-clad
land. The males were provided with great canine
teeth, which served them as formidable weapons.” *

no less astonishing and remarkable than the well known meta-
morphoses of the butterfly. * * * An examination of the
human embryo in the third or fourth week of its evolution
shows it to be altogether different from the fully developed
man, and that it exactly corresponds to the undeveloped em-
bryo-form presented by the ape, the dog, the rabbit, the horse,
and other mammals, at the same stage of their ontog’eny (germ
history), which may be demonstrated by placing the respective
embryos side by side. At this stage it is a bean-shaped body of
very simple structure, with a tail behind, and two pairs of pad-
dles, resembling the fins of fish, and totally dissimilar at the
sides to the limbs of man and other mammals. Nearly the
whole of the front half of the body consists of a shapeless head,
without a face, on the sides of which are seen gill-fissures and
gill-arches, as in fishes. * * * The human embryo passes
through a stage in which it possesses no head, no brain, no
skull; in which the trunk is still entirely simple and undivided
into head, neck, breast, and abdomen, and in which there is no
trace of arms or legs.”—Hrnst Heinrich Haeckel, “The Evolution
of Man,” Vol. I, pp. 3, 18, 253.

* Mr, Darwin continues: “ At a much earlier time the uterus
was double; the excreta were voided through a cloaca, and the
eye was protected by a third eyelid or nictitating membrane.
At a still earlier period the progenitors of man must have been
aquatic in their habits, for morphology plainly tells us that our
lungs consist of a modified swim-bladder, which once served as
a float. The clefts on the neck in the embryo of man show
where the branchiz once existed,” &c., &c.

DARWIN ONLY CORROBORATES IUNTER. 83

Again, on page 138 of the same volume, Mr. Darwin
says: ;

“The early progenitors of man were, as previously
stated, probably furnished with great canine teeth; but
as they gradually acquired the habit of using stones,
clubs, or other weapons for fighting with their enemies,
they would have used their jaws and teeth less and
less. In this case the jaws and the teeth would have
become reduced in size, as we may feel sure from nu-
merous analogous cases.” *

"Dr. John Hunter, writing nearly one hundred years
before Mr. Darwin’s time, says (“The Human Teeth,”
p- 29):

«The use of the cuspidati would seem to be to lay
hold of substances, perhaps even living animals. They
are not formed for dividing, as the incisors are, nor
are they fit for grinding. We may trace in these teeth
a similarity in shape, situation, and use, from the most
imperfectly carnivorous animal—which we believe to
be the human species—to the most perfectly carnivo-
rous, namely, the lion.”

The editor of Dr. Hunter’s work, Mr. Thomas Bell,
F.R.S., comments as follows on the above extract:

«That our conclusions as to the functions of an
organ as it exists in man, when drawn exclusively from
analogous structures in the lower animals, will fre-

*«The jaws, together with their muscles, would then have
become reduced through disuse, as would the teeth, through the
not well understood principles of correlation and the economy of
growth; for we everywhere see that parts which are no longer
of service are reduced in size.” —‘‘Descent of Mun.”

84 THE CANINE TEETH.

quently prove erroneous, is strikingly shown in these
observations on the use of the cuspidatus. The simple
and obvious use of this tooth, in the human species, is
to tear such portions of food as are too hard or tough
to be divided by the incisors; and we frequently find
it far more developed in animals which are known to
be exclusively frugivorous. Not only is its structure
wholly unadapted for such an object as that assigned
to it in the text, but there is no analogous or other
ground for supposing that man was originally con-
structed for the pursuit and capture of living prey.
His naturally erect position and the structure of the
mouth would render this impossible by the means in-
ferred by Hunter; and the possession of so perfect an
instrument as the hand obviates the necessity of his
ever employing any other organ for the purpose of
seizing or holding food of whatever description.”

Prof. William Youatt says (‘The Horse,” p. 226):

“ At the age now under consideration (the fourth
. year) the tushes are almost peculiar to the horse, and
castration does not appear to prevent or retard their
development. All mares, however, have the germs of
them in the chambers of the jaws, and they appear
externally in the majority of old mares. Their use is
not evident. Perhaps in the wild state of the horse
they are weapons of offense, and he is enabled by
them to more firmly seize and more deeply wound his
enemy.” *

* Prof. C. S. Tomes says: ‘In the domestic races the tusks of
boars are much smaller than in the wild animal, and it is a curi-
ous fact that in domestic races which have become wild, the
tusks increase in size at the same time that the bristles become
more pronounced. Mr. Darwin suggests that the renewed

THEIR PHYSIOLOGICAL RELATIONS, 85

Surgeon J. H. Winter, the author of a work entitled
“On the Horse,” says:

“Tt is difficult to assign their use. Their position
precludes the possibility of their being used as weapons
of offense or defense. They may be viewed as a link
of uniformity so commonly traced in the animated
world.”

Prof. William Percivall says that the cutting of the
tushes causes the constitution more derangement than
all the other teeth, and Prof. Youatt and other high
authorities entertain similar views. ‘The present chap-
ter, therefore, is a proper one in which to discuss “ the
effects of dentition on the system generally.” The
discussion of the subject is left to well-known men.
Messrs. Youatt and Percivall were many years ago the
editors of “The Veterinarian,” but their books are
probably the best monuments to their memory. Prof.
William Williams is the President of the Edinburgh
Veterinary College. Prof. Youatt says (“ The Horse,”
p- 230):

“This is the proper place to speak of the effect of
dentition on the system generally. Horsemen in gen-
eral think too lightly of it, and they scarcely dream of
the animal suffering to any considerable degree, or

growth of the teeth may perhaps be accounted for on the prin-
ciple of correlation of growth, external agencies acting on the
skin, and so indirectly influencing the teeth.”

A strictly analogous result might or might not follow in the
case of the horse. If so, the tushes would probably be used as
weapons of offense and defense. It is reasonable to suppose that
they were so used by the early progenitors of the horse, whose
large tushes aye described in the succeeding chapter by Prof
Marsh.

86 THE CANINE TEETH.

absolute illness being produced. Yet he who has to
do with young horses will occasionally discover a con-
siderable degree of febrile affection which he can refer
to this cause alone. Fever, cough, catarrhal and cuta-
neous affections, diseases of the eyes, diarrhea, dysen-
tery, loss of appetite, and general derangement will
frequently be traced to irritation from teething. It is
a rule scarcely admitting ef the slightest deviation,
that, when young horses are laboring under febrile
affection, the mouth should be examined, and if the
tushes are prominent and pushing against the gums, a
crucial incision should be made over them.” *

Prof. Percivall says (“ Hippopathology,” vol. ii, p.
225):

“There was a time when I treated the subject of
dentition so lightly as to think that horses never suf-
fered from such a cause. Experience, however, has
altered my opinion. I now frequently discover young
horses with disorders or febrile irritations the produc-
tion of which I hesitate not to ascribe to teething.
Many years ago I was consulted concerning a horse
which had fed sparingly for a fortnight and lost rap-
idly in condition. His owner, a veterinary surgeon,
was apprehensive about his life. Another surgeon was
of opinion that the ‘cudding’ arose from preternatural

* Prof. Youatt’s real sentiments are doubtless here expressed,
but, unfortunately for his consistency, on page 227 of the same
work, in speaking of the derangement caused by teething in
children and dogs, he says: “The horse appears to feel little
inconvenience. The gums and palate are occasionally some-
what hot and swollen, but the slightest scarification will remove
this.” Perhaps Prof. Youatt, like Prof. Percivail, changed his
opinion late in life, and neglected to remove the blemish from
his book,

WHAT CHANGED PROF. PERCIVALL’S MIND. 87

bluntness of the molar teeth, which were filed. It
was after this that I saw the horse, and I must confess
I was at first quite as much at a loss to offer a satisfac-
tory interpretation of the case as others had been.
While meditating, however, after my inspection of the
horse, On the apparently extraordinary nature of the
case, it struck me that I had not seen the tushes. I
went back into the stable and discovered two little
tumors, red and hard, in the situation of the inferior
tusks, which, when pressed, gave the animal insuffer-
able pain. I instantly took out my pocket-knife and
made crucial incisions through them both, from which
moment the horse recovered his appetite, and by de-
grees his wonted condition. ‘This case was the turn-
ing point in my practice, and caused me to look more
closely into dentition. |

“'The cutting of the tushes, which may be likened
to the eye-teeth of children, costs the constitution
more derangement than all the other teeth put to-
gether; on which account, no doubt, it is that the
period from the fourth to the fifth year proves so crit-
ical to the horse. Any disease, pulmonary in particu-
lar, setting in at this period, is doubly dangerous. In
fact, teething is one cause of the fatality among young
horses at this period.

“D’Arboval tells us to observe how the vital energy
becomes augmented about the head, and upon the
mucous surfaces in particular. He says: ‘A local
fever originates in the alveolar cavities. The gums
become stretched from the pressure of the teeth against
them. They dilate, sometimes split, and are red, hot,
and painful. The roots compress the dental nerves
and irritate the periosteal linings of the alveolar cayi-
ties. These causes will enable us to explain many

88 THE CANINE TEETH.

morbid phenomena in horses about this, the most crit-
ical period of their lives.’

“ When young horses are brought to me now for
treatment,” continues Prof. Percivall, “1 invariably
examine the teeth. Should the tusks be pushing
against the gums, I let them through by incisions
over their summits, and I extract any of the tempo- —
rary teeth that appear to be obstructing the growth of
the permanent. In this way I feel assnred I have seen
catarrhal and bronchial inflammations abated, coughs
relieved, lymphatic and other glandular tumors about
the head reduced, cutaneous eruptions got rid of, de-
ranged bowels and urinary organs restored, appetite
returned, and lost condition repaired.

“Tam quite sure too little attention has been paid
to the teeth in the treatment of young horses, and I
would counsel those who have such charges by no
means to disregard this remark, trifling as it may
appear. The pathognomonic symptoms calling our
attention, whether in young or old horses, if not to
the teeth themselves, to the mouth in general, are
large discharges of saliva from the mouth, with occa-
sional slobbering; cudding of the food; difficulty of
mastication or deglutition, or both, and stench of buc-
cal secretion, perhaps of the breath as well.”

Prof. Percivall continues the discussion of the sub-
ject of dentition and its effect on the health of the
horse, dwelling more particularly on the disorder
known as lampas. He says:

“There is connected with dentition another pecu-
liarity in the horse which we must not allow to pass
unnoticed. Although the period of teething, properly

LAMPAS CAUSED BY TEETHING. 89

speaking, may be said to terminate at the fifth year,
yet we must recollect it has been satisfactorily demon-
strated that there is a process of growth going on in
the teeth throughout the remainder of life; so that, in
fact, at no period may the animal be said to be free
from the influence of dentition. This accounts for
lampas occurring in old as well as young horses, and
furnishes my mind with strong proof that the tumidity
of the bars of the mouth is dependent on operations
going on in the teeth, and on that cause alone.

“What we nowadays understand by lampas is an
unnatural prominence or tumidity of the cartilaginous
bars forming the roof of the mouth. Naturally, the
bars are pale-colored, whereas in a mouth affected with
lampas they become red and tumid, losing their eir-
eumflecture, and swelling to a level with the crowns of
the incisor teeth, and in some cases even beyond them.
This apparent augmentation of substance is ascribable
to congestion of blood-vessels, but not to that alone.
I believe that in many cases there will be found to be
some serous and albuminous infiltration into the cel-
lular membrane attaching the bars to the hard palate,
and that this will account for the length of time the
swelling sometimes continues, as well as for the little
relief, in regard to their diminution, which in such
cases attends lancing of the gums.

“ Although in young horses it is, I believe, admitted
that lampas is caused by the cutting of the teeth, yet
in old horses there are those who ascribe its produc-
tion to other causes, and imagine it has a great deal to
do with a horse’s health, or rather with his feeding.
That lampas may in some cases be the cause of tender-
ness in mastieation, I do not deny; but, at the same
time, I think I may safely affirm that in nine cases out

90 THE CANINE TEETH. ~

of ten the cause of loss of appetite will be found else-
where. The reason why lampas appears in aged horses
is, in my opinion, as before stated, on account of the
continuance of the process of growth in the teeth
throughout life, with the nature and laws of which we
are, in our present state of knowledge, too little ac-
quainted to pretend to say why it should exist in one
horse and not in another, or why it should only at
times appear in the same horse.

“Ts lampas a disease? The complaints which daily
reach our ears persuade us it is. Every groom having
an unthriving horse, or one that does not feed, is sure
to search for lampas. If he finds it, in his mind the
cause of lack of thrift is detected, and the remedy
obvious—burning. Many a horse has been subjected
to this torturing operation, and has thereby got added
to his other ailments a foul, stouan ys carious sore on
the roof of his mouth.

“Supposing that lampas be owing to the teeth, do
not the teeth require removal, and not the bars of the
mouth? In cutting or burning away lampas we mis-
take the effect for the cause. If lampas is not produced
by the irritation of teething, then I would like to be
informed what does cause it.”

Prof. Youatt says of lampas (“The Horse,” p. 219):

“Tt may arise from inflammation of the gums,
propagated to the bars when the colt is shedding his
teeth—young horses being more subject to it than
others—or from some febrile tendency in the consti-
tution generally, as when a young horse has lately
been taken from grass, and has been over-fed or insuf-
ficiently exercised. It is well to examine the grinders,

eS

a”

MASHES AND LANCING RECOMMENDED. 91

and more particularly the tushes, in order to ascertain
whether they are making their way through the gums.
If so, incisions should be made across the swollen
gums, and immediate relief will follow. At times it

‘ appears in aged horses, the process of growth in the

teeth of the horse continuing during life.

“'T’he brutal custom of farriers, who sear and burn
the bars with a red hot iron, is most objectionable. It
is torturing the horse to no purpose, and may do seri-
ous injury. In a majority of cases the swelling will
subside without medical treatment. A few mashes
and gentle alteratives will give relief, but sometimes
slight incisions across the bars with a lancet or pen-
knife may be necessary. Indeed, scarification of the
bars in lampas will seldom do harm, though it is not
as necessary as is generally supposed.”

Concerning “ Diseases occurring during Dentition”
Prof. William Williams says (“ Principles and Practice
of Veterinary Surgery,” p. 476):

“In the horse the temporary grinders are replaced
by permanent ones when he is from three to four years
old, and in the ox at from two years and six months
to two years and nine months. In cattle the cutting
of the permanent molars is occasionally a matter of -
some difficulty owing to the unshed crowns of the
temporary teeth becoming entangled with the new

teeth, and thus proving a source of irritation and pre-

venting the animal from feeding. In some parts of
the country such animals are called ‘rotten,’ from their
emaciated condition, and perhaps from the fetor ema-
nating from thé mouth. When cattle of this age stop
feeding, lose condition, or drivel from the mouth, the

92 - HE CANINE TEETH.

teeth should be examined, and if the unshed molars
are causing irritation, they should be removed with
the forceps. Hundreds of young cattle have been sac-
rificed from this cause—actually dying of starvation.
In the horse the same condition of the grinders may
exist, but it is very unusual. The corner incisors,
however, may present the same anomalous condition.
Horses from four years to four years and six months
old should have their teeth examined occasionally to
see if all is going on well.

“ Horses at four years old are subject to a distressing
cough. At this age the third temporary grinder is
replaced by its permanent successor, and at the same
time the sixth grinder is being cut. Some irritation
exists in the gums during the eruption of all the teeth,
and in some instances it is excessive, extending from
the gums to the fauces and larynx. ‘This 1s particu-
larly the case with the sixth grinder, and as a result of
the extension of the irritation, cough is excited, usually
in the morning, when the animal begins to feed. It
is loud, sonorous, and prolonged, the horse frequently
coughing twenty, thirty, or even forty times without
ceasing. It is a throat cough, originating in laryngeal
irritation.

“'The treatment for this, which may be truly said to
be a tooth-cough, is careful dieting on crushed food;
hay, not much bran; grass, if in season, or roots if
grass 1s not obtainable; alkaline medicines, more par-
ticularly the bicarbonate of soda; gentle aperients
occasionally, if the bowels be irregular. If the feeces
are fetid the fetor will be much diminished by a few
doses of the hyposulphite of soda, the mouth to be gar-
gled with some cooling mixture, such as the borate of
soda or alum.”

DENTITION FEVER. 93

Of “Dentition Fever” Prof. Williams says (“ Prin-
ciples and Practice of Veterinary Surgery,” p. 479):

“ Horses from three to four years old are more sub-
ject to this species of dental irritation than those of a
more tender age, and it is well known among horsemen
that they will stand more fatigue at a more tender age
than they will at this. The reason is because teething
is now at the hight of its activity. When the animal
is three years-old, eight permanent grinders are being
cut, and four permanent incisors are in active growth
within the jaws. At four years of age the same num-
ber of grinders are out, and the same number of inci-
sors are at a more advanced stage of growth within the
jaws, in addition to the canine teeth, which make
their appearance about this time.

“ No wonder then that the eruption of so many teeth
is a source of irritation and fever. The best treatment
is to throw the animal off work, turn him to grass if
the weather permits, or into a loose box in a well ven-
tilated spot, and give him rest until the process of den-
tition is completed. Ifthe gums are red and swollen,
lancing them will prove a source of great relief.”

On page 505 Prof. Williams, in speaking of crib-
biting and wind-sucking, says: “Want of work and
the irritation of teething are generally the causes of
these vices.”

CHAPTER ¥.

THE REMNANT TEETH.

Usually regarded as Phenomenons.—The Name.—Traced to
the Fossil Horses, in which (in the Pliocene Period) they
“Ceased to be Functionally Developed.”—Nature’s Meta-
morphoses.—* The Agencies which are at work in Modeling
Animal and Vegetable Forms.’”—Why Remnant Teeth are
often, as it were, Prematurely Lost.—Fossil Horses and a
Fossil Toothed-Bird.

THE Remnant or “so-called wolf-teeth” are one of
the most interesting features of the horse’s dental sys-
tem. They are generally regarded as phenomenons,
but their line of descent is as direct as that of the first
premolars (grinders), which have, as it were, almost
absorbed them, and have increased in bulk nearly in
proportion to the decrease in bulk of the Remnant
teeth.

As the word “ wolf” is another name for that which
is hurtful or destructive, and as these teeth as well as
supernumerary teeth, with which, however, they should
never be confounded, sometimes do injury, the generic
name, “ wolf-teeth,” is not a bad one. But, since these
particular teeth are hereditary, being beyond doubt the
remains of teeth that were once functionally developed,
they require a specific name; I have therefore adopted
the name ReMNANT TEETH. :

PROF. MARSH’S RESEARCHES. 95

In the evolution of the horse from an animal of
about the size of a fox to bis present proportions, it is
not strange that radical physical changes, of the teeth
as well as other organs, should have oceurred, or that
they are in harmony with his bodily requirements as
well as his usefulness to man. Small, four-toed limbs
would support the body of an animal no larger than a
fox or a sheep, but they would require additional size
and strength to support the small horse (Hipparion)
of the Pliocene period, or the large horse of the present
period (Equus). This additional strength was gradu-
ally acquired by the enlargement of the limbs and the
solidification, as it were, of four toes into one, it being
as natural, in conformity to the law of adaptation, for
a line of suceeeding animal forms to undergo podaly
changes as for an individual form to do so.

During these metamorphoses equally varied and
interesting changes occurred in the horse’s dental sys-
tem, which are described by Prof. O. C. Marsh, of Yale
College, in the article “ Horse, Fossil,” in “ Johnson’s
New Universal Cyclopedia (vol. ii, p. 996). He givesa
general description of the changes that have occurred
in species of three geological periods, namely, the
Pliocene, Miocene, and Eocene, those of the two last
named having forty-four functionally developed teeth.
The part of the article which refers to the teeth is as
follows:

“Tn the Pliocene tertiary period the horse was rep-
resented by several extinct genera, the best known be-
ing Hipparion (or Hippotherium). The species are
small, as the name implies, Hipparion being a dimin-
utive from the Greek hippos, a ‘horse.’ In the upper
molar teeth there is in Hipparion, on the anterior por-

96 THE REMNANT TEETH.

tion of the inner side, an isolated ellipse of enamel
inclosing dentine, and not joined with the main body
of the tooth by an isthmus of dentine, as in Lguus, at
least until the teeth are nearly worn out. Anchippus,
also from the Pliocene, resembled in its teeth Anchi-
therium of the Miocene, a genus now considered as
typical of a family distinct from that of the horse. In
Anchitherium the molars have short crowns, devoid of
cement, and are inserted by distinct roots. The Mio-
cene species were not larger than a sheep. The Hocene
representatives of the group were still smaller, the
largest hardly exceeding a fox in size. They belong
to the genus Orohippus. ‘The dentition is very simi-
lar to that of Anchitherium, but the first upper pre-
molar is larger and the succeeding ones smalier than
in that genus. The diastema, or ‘ place for the bit, is
distinct. ‘The canines are large, and near the incisors.
The crowns of the molars are short and destitute of
cement, and the skeleton is decidedly equine in its
gencral features.

“The gradual elongation of the head and neck may
be said to have already begun in Orohippus, if we
compare that form with other most nearly allied mam-
mals. The diastema wags well developed even then, but
increased materially in succeeding genera. The num-
ber of teeth remained the same until the Pliocene,
when the front lower premolar was lost, and subse-
quently the corresponding upper tooth ceased to be fune-
tionally developed.* 'The next upper premolar, which
in Orohippus was the smallest of the six posterior

* The italics are mine. This ‘corresponding upper tooth
that ceased to be functionally developed,” is the identical tooth
that now appears as a mere remnant.

THE LARGE TUSHES OF OROHIPPUS. 9%

teeth, rapidly increased in size, and finally became the
largest of the series.. The grinding teeth had at first
very snort crowns, without cement, and were inserted
by distinct roots. In Plocene species the molars be-
came longer, and were more or less coated with cement.
The modern horse has very long grinders, without
true roots, which are covered with a thick external
layer of cement. The large canines of Orohippus be-
eame gradually reduced in the later genera, and the
characteristic ‘mark’ upon the incisors is found only
in the later forms. It is an interesting fact that the
peculiarly equine features acquired by Orohippus are
retained persistently throughout the entire series of
succeeding forms.” *

* «The ancient Orohippus had all four digits of the fore-feet
well developed. In Mesohippus, of the next period, the fifth
toe is only represented by a rudiment, and the limb is supported
by the second, third, and fourth, the middle one being the
largest. Hipparion of the Later Tertiary still has three digits,
but the third is much stouter, and the outer toes have ceased to
be of use, as they do not touch the ground. In Equus the lat-
eral hoofs are gone, and the digits themselves are represented
only by the rudimentary splint-bones. The middle or third
digit supports the limb, and its size has increased accordingly.
Tue corresponding changes in the posterior limb of these genera
are very similar but not so striking, as the oldest type (Orohip-
pus) had but three toes behind. The earlier ancestor of the
group, perhaps in the lowest Eocene, probably had four on this
foot and five in front. Sucha predecessor is as clearly indicated
by the feet of Orohippus as the latter is by its Miocene relative.
A still older ancestor, possibly in the Cretaceous, doubtless had
five toes on each foot, the typical number in mammals. This
reduction in the number of toes may perhaps have been due. to
elevation of the region inhabited, which gradually led the ani-
mals to live on higher ground, instead of the soft lowlands,
where a many-t6ed foot would be most useful.”—Prof. 0. 0.
Marsh.

5

98 HE REMNANT TEETH.

The article closes as follows:

“Such is, in brief, a general outline of the more
marked changes that appear to have produced in
America the highly specialized modern Equus from
its diminutive, four-toed predecessor, the Hocene Oro-
hippus. The line of descent appears to have been
direct, and the remains now known supply every im-
portant intermediate form. Considering the remark-
able development of the group throughout the entire
tertiary period, and its existence even later, it seems
very strange that none of the species should have sur-
vived, and that we are indebted for our present horse
to the Old World.” *

* The following extracts from Prof. C. 8. Tomes’s “ Dental
Anatomy, Human and Comparative” (pp. 247-8, 254-5), explain
some of the causes of the metamorphoses described by Prof.
Marsh: ‘He would indeed be a rash man who ventured to as-
sert that we had recognized all the agencies which are at work
in the modeling of animal and vegetable forms; but it is safe to
say that, at the present time, we are acquainted with several
agencies which are in constant operation, and which are com-
petent to profoundly modify animals in successive generations.
We know of ‘natural selection,’ or ‘survival of the fittest,’ an
agency by which variations beneficial to their possessors will be
preserved and intensified in successive generations; of ‘sexual
selection,’ which operates principally by enabling those pos-
sessed of certain characters to propagate their race, while others
Jess favored do not get the opportunity of so doing; of ‘ con-
comitant variation’ between different parts of the body, an
agency much more recondite in its operations, but by which
agencies affecting one part may secondarily bring about altera-
tions in some other part.

“The doctrine of natural selection, or survival of the fittest,
is as applicable to the teeth of an animal as to any part of its
organization, and the operation of this natural law will be con-
stantly tending to produce advantages or ‘adaptive’ differences.
On the other hand, the strong power of inheritance is tending to

a

NOT RARE, BUT EASILY LOST. $9

Remnant teeth are not rare, but it is rare for them
to persist in the jaws till even middie age. However,

preserve even that which, in the altering conditions of life, has
become of very little use, Thus we may understand rudimentary
teeth to be teeth which are in process of disappearance, having
ceased to be useful to their possessors, but still for a time,
through the influence of inheritance, lingering upon the scene.
Some teeth have disappeared utterly. Thus the upper incisors
of ruminants are gone, and no rudiments exist at any stage;
others still remain in a stunted form, and do not persist through-
out the iifetime of the animal, as, for instance, the first premo-
lars of the horse, or two out of the four premolars of most bears,

“Teeth are profoundly susceptible of modification, but amid
all their varied forms, the evidences of descent from ancestors
whose teeth departed jess from the typical mammalian dentition
are clearly traceable by the existence of rudimentary teeth and

. other such characters. * * * The power of inheritance is
onstantly asserting itself by the retention, for a time at least,
of parts which have become useless, and by the occasional reap-
pearance of characters which have been lost. * * * Things
that are rudimentary often teach us most; for being of no pres-
ent use, they are not undergoing that rapid change in adaptation
to the animal’s habits which may be going on in organs that
are actively employed.”

Horses are not the only animals that have bad or are having
changes in their dentition. Mr. C. R. Darwin says (“ Descent of
Man,” vol, i, p. 25): “It appears as if the posterior molar or
wisdom-teeth were tending to become rudimentary in the more
civilized races of men. They are rather smailer than the other
teeth. In the Melanian races, on the other hand, the wisdom-
teeth are usually furnished with three separate fangs, are gen-
erally sound, and differ in size from the other molars less than
in the Caucasian races. Prof. Schaaffhausen accounts for this
difference between the races by ‘the posterior dental portion of
thé jaw being always shortened’ in those that are civilized, and
this shortening may, I presume, be safely attributed to civilized
men habitually feeding on soft, cooked food, and thus using
their jaws less. Iam informed by Mr. Brace that it is becoming
quite a common practice in the United States to remove some

100 THE REMNANT TEETH.

there may be cases where they never appear; but it
hy no means follows that because a horse is not im pos-
session of them that he never had any. There are
rarious causes for their frequent absence, but the chicf
cause is their small size. Remnant
teeth of the lower jaw, which are
very rare, are probably cases of “re-
version to a former state.” * If these
latter teeth were not expelled in the
manner explained below by Mons.
Leecoq, the probability 1s that they would not long
withstand the friction of the bit. The upper teeth,
however, while they may sometimes be expelled by the
bit, are comparatively little disturbed by it, which
probably accounts for their now and then remaining
in the jaws for years. Another reason for their per-
sistence is that their roots are long in proportion to
their bodies. The reason why these teeth should not
be confounded with supernumerary or abnormal teeth
will appear in the succeeding chapter, which is devoted
to the consideration of the latter.

Monsieur Lecoq gives cogent reasons for the fre-
quent absence of Remnant teeth. He says:

Rem. iant teeth ; natural
size.— Original.

“Supplementary molars are sometimes met with in
front of the true ones, and there may be four of them,
two in either jaw, above and below. They are small
teeth, having but little resemblance to the others, are
frequently shed with the first deciduous molar, and
are not replaced. The first replacing (permanent)
molar is always a little more elongated than that

of the molar teeth of children, as the jaw does not grow large
enough for the perfect development of the normal number.”

* See the second reference note, page 80.

= = %
Pa

HOW THEY MAY BE LOST. 101

which it succeeds, and it frequently expels at the same
time the supplementary molar; so that if forty-four
teeth be developed in the male horse, it is very rare
that they are all present at the same time.”

That Remnant teeth are usually regarded as phe-
nomenons is abundantly proved by some of the ex-
tracts that follow. In “Johnson’s New Universal
Cyclopedia” (p. 995), article ““ Horse,” it is said:

“An additional small tooth is occasionally found in
advance of the upper molar series. ‘his tooth, when
present, is the smallest of all the teeth, and, as it has
neither predecessor nor successor, its nature is in
doubt.”

As the nature of these teeth appeared to be clearly
explained in the article “ Horse, Fossil,” which imme-
diately follows that on the “ Horse,” I wrote to Prof.
Joseph Leidy, telling him I believed the “ wolf-teeth”
were the remnants of the teeth that “ceased to be
functionally developed,” and asked his opinion about
the matter. Writing under date of “Philadelphia,
Novy. 26, 1878,” he said:

es Oe

“I think you are right in supposing that
the little premolars referred to by Prof. Marsh as the
‘corresponding upper teeth,’ which ‘ceased to be func-
tionally developed,’ are the so-called ‘wolf-teeth.’ ”

Another letter, addressed to Prof. Theodore Gill,
elicited the following reply, which was dated “Smith-
sonian Institution, Washington, D. C., Nov. 25, 1878:

* * * “The complete dentition of the adult

horse is represented by the formula: L, $; C., 4;
D.,4; P.M.,3; M. 2x2=42. The ‘small wolf or

102 THE REMNANT TEETH.

supernumerary tooth that appears in front of the first
upper premolar,’ is the more or less persistent first
deciduous molar (d 1) of the first series, which is not
succeeded by a first premolar. The premolars are con-
sequently P. M., 2, 3, and 4 of the typical educabilian
dentition.”

Prof. Richard Owen, who, like Drs. Gill and Leidy,
has a clear conception of the subject, says:

“The second incisor appears between the twentieth
and fortieth days, and about this time the first small,

deciduous premolar takes its place * * * The

representative of the first premolar is a very small and
simple rudiment, and is soon shed.”

Surgeon Charles Parnell, in a letter to the editor of
“The Veterinarian” (1867, p. 287), says:

“Tn reading Prof. George Varnell’s articles on some
of the diseases affecting the facial region of the horse’s
head, I notice a description of wolf-teeth. He says:
‘They have been supposed to be the cause of disease in
the eyes of horses. This idea, however, is quite erro-
neous; therefore I shall not occupy any space in dis-
cussing this traditional error. Well, I can safely say
that I have in my time extracted a great many of these
teeth, and not merely because they existed, but because
there was a weeping from both eyes, the cause of which
was attributed to wolf-teeth, and generally in the
course of a few weeks the weeping has ceased. But
what convinces me that they do affect the eye is that
in several cases where there were weeping and weak-
ness of one eye only, I have found a wolf-tooth on the
affected side only, and the recovery of the eye has in-
variably followed the extraction of the tooth. The

HORSES WITHOUT EARS. 103

mucous membranes and lachrymal glands appear to
be the parts affected, undoubtedly from some connec-
tion through the nerves. If these teeth are allowed to
remain in the horse’s mouth, the sight will become
more or less impaired.”

Might not this plan (extracting the teeth), if adopted
by ali surgeons, eventually rid horses of the so-called
wolf-teeth? Nature may be aided or injured. The
effect of interfering with nature is illustrated by the
following extract from Prof. W. Youatt's | work, “ The
Horse” (p- 154):

“The custom of cropping the ears of the horse orig-
inated, to its shame, in Great Britain, and for many
years was a practice not only cruel to the animal, but
deprived it of much of its beauty. It was so obsti-
nately persisted in that at length the deformity be-
came in some hereditary, and a breed of horses born
without ears was produced.”

Extracting the Remnant teeth appears to aid rather
than injure nature. The practice is therefore as com-
mendable as the cropping of the ears is reprehensible,
and if the same result should follow that Prof. Youatt
says followed the cropping of the ears, it ought to be
adopted.

C. D. House, an American veterinary dentist, like
Surgeon Parnell, invariably extracts the Remnant
teeth. He not only claims that they sometimes injure
the eyes, but that in some cases, when they encroach
on the maxillary branch of the fifth pair of nerves,
they cause the horse to act as if insane. He says he
has more than once extracted these teeth when the
“insane” horse was in an open field. When the tooth

104 THE REMNANT TEETH.

is drawn and the animal is relieved, it looks around
and stares and acts as if wondering where it is and how
it got there. Not more than one horse in twenty pos-
sessing these teeth, he says, ever suffers injury to its
eves.

Surgeon R. Jennings of Detroit has examined many
fetuses and always found Remnant teeth germs; dur-
ing 37 years’ practice, in more than 100 deaths under
two years, not a single instance occurred where these
teeth, or the germs which produce them, were not
found. They will be found usually at the age of two
years.

Veterinary Dentist J. Ramsey of Boston treated a
{-year-old horse in 1881 that had been “out of con-
dition” for several years, and consequently had had
several owners. He discovered a long Remnant tooth
with such a vicious inclination toward the roof of the
mouth as to interfere with the use of the tongue. As
soon as the tooth was extracted the horse began to eat.

Prof. Williams says of Remnant teeth (“ Principles
and Practice of Veterinary Surgery,” p. 479):

“ Small supernumerary teeth are often met with in
front of the grinders, called ‘wolf-teeth.’ They have
been supposed to be a cause of ophthalmia, but this is
doubtful. They can produce no inconvenience; but
if requested to extract them a practitioner can hardly
refuse. The best method is to remove them with the
tooth-forceps.

“The question as to the influence of the teeth on
the eyes might perhaps be deemed worthy of discus-
sion, inasmuch as the dental nerve is a branch of that
which supplies the eyes with common sensibility,
namely, the fifth. The older writers maintained that

MOON-BLINDNESS. 105

¢moon-blindness’ was due to wolf-teeth, and the first
procedure in the treatment was their removal. Now-
adays, however, the supposition is not carried quite so
far, and the utmost that can be said is that the irrita-
tion of teething may be an exciting cause of ophthal-
mia in animals whose constitutions are hereditarily or
otherwise predisposed to the disease, and the removal
of supernumerary teeth, or lancing the gums, may pos-
sibly be followed by some remission of the ophthalmic
symptoms.” :

Prof. Youatt thus accounts for Remnant teeth:

“Tn a few instances the permanent teeth do not rise
immediately under the temporary, but somewhat by
their side. Then, instead of the gradual process of ab-
sorption, the root, being compressed sideways, dimin-
ishes throughout its whole bulk. The crown dimin-
ishes also, and the tooth is pushed out of its place to
the forepart of the first grinder, and remains for a con-
siderable time under the name of a wolf-tooth, causing
swelling and soreness of the gums, and frequently
wounding the cheeks. They would be gradually quite
absorbed, but the process might be slow and the an-
noyance great; therefore they are extracted.”

Prof. Youatt’s theory is unique, but it fails to give
a satisfactory explanation of the “ so-called wolf-teeth.”
That a tooth should be pushed out of its place is sim-
ple enough; but why would the first upper temporary
grinder remain in the gum and take root and the first
lower not? That “they would be gradually quite ab-
sorbed,” is disproved by the fact that they sometimes
persist tillold age; and this fact also disproves the
assertion that “they are extracted.” Some surgeons

106 FOS3IL HORSES’ TEETH.

do not extract them. Prof. Youatt doubtless meant
to say they should be extracted.

As Remnant teeth are found functionally devel-
oped in the jaws of fossil horses—in which they were
the largest of all the teeth—a few extracts from the
works of well-known men concerning fossil horses and
their teeth will be appropriate as a conclusion to this
chapter. Prof. Richard Owen says (“ Odontography,”
vol. i, p. 575):

“ Ouvier was unable, from the materials at his com-
mand, to detect any characters in the bones or teeth
of the different existing species of Hguus, or in the
fossil remains of the same genus, by which he could
distinguish them, save by their difference of size.
Among the numerous teeth of a species of Hguus as
large as a horse fourteen and a half hands high, col-
lected from the Oreston eavernous fissures, 1 have
found specimens clearly indicating two distinct spe-
cies, so far as specific differences may be founded on
well-marked modifications of the teeth.

“One of these, like the ordinary Hqguus fossilis of
the drift and pleistocene formations, differs from the
existing Hguus caballus by the minor transverse diam-
eter of the molar teeth; the other, in the more com-
plex and elegant plication of the enamel,* and in the

*In Prof. Gwen’s “ History of British Fossil Mammals and
Birds” (pp. 393-4), the “elegant plication of the enamel” on
the crown of this tooth is illustrated. Prof. Owen says: “Fig.
153 illustrates the character, above adverted to, of the complex
plication of the enamel, as it appears on the grinding surface of
a partially worn upper molar tooth, the second of the right side.
The length of this tooth is three inches four lines, and the fangs
had not begun to be formed. One cannot view the elegant fold-
ings of the enamel in the present fossil teeth, and in those of

TEETH UNEARTHED AT ORESTON, ENG. 107

bilobed posterior termination of the grinding surface
of tue last upper molar, more closely approximates to
the extinct horse of the Miocene period, which Herr
von Meyer has characterized under the name of Lguus
caballus primigenius. The Oreston fossil teeth differ,
however, from this in the form of the fifth or internal
prism of dentine in the upper molars, aud in its con-
tinuation with the anterior lobe of the teeth, the fifth
prism being oval and insulated in the Lguus primi-
genius of Von Meyer.

«The Oreston fossil teeth, which in their principal
characters manifest so close a relationship with the
Miocene Equus primigenius, differ, like the later drift
species (7. fossilis), from the recent horse in a greater
proportional antero-posterior diameter of the crown,
and also in a less produced anterior angle of the first
premolar. I have named this British fossil horse
Equus plicidens. he fossil horse (Zy. ewrvidens) of
South America, which coexisted with the megathe-
rium,+ and, like it, became extinct apparently before

the more ancient primigenial species (Hippotheria) of the conti-
nental Miocene deposits, without being reminded of the peculiar
character of the enamel of the molars of the Elasmotherium, in
which it is folded in elegant festoons. This extinct pachyderm,
which surpassed the rhinoceros in size, resembled that genus
very closely in the general disposition of the folds of enamel in
the grinding teeth, but agreed with the modern horse in the
deep implantation of those teeth by an undivided base. The
Elasmothere appears, therefore, to have formed one of the links,
now lost, which connected the horse with tue rhinoceros ; and
it is interesting to observe that some of the extinct species of
horse, in the analogous complexity of the enamel folds, more
closely resembled the Elasmothere than do the present species.”

+ “ The teetiv of this most gigantic of the extinct quadrupeds
of the sloth tribe are small in proportion to the size of the ani-

108 FOSSIL HORSES’ TEETH.

the introduction of the human race, differs from the
existing horse by the greater degree of curvature of
the upper molars.”

The following account of two fossil molar teeth of an
extinct species of horse, discovered in South America,
may be found in Prof. Owen’s “ Fossil Mammalia and
-Mammalia,” (pp. 108-9) :

“ Notice of the remains of a species of Equus, found
associated with the extinct Hdentals and Toxodon at
Punta Alta, in Bahia Blanca, and with the Mastodon
and Toxodon at Santa Fé, in Entre Rios—The first of
these remains is a superior molar tooth of the right
side. It was imbedded in the quartz shingle, formed
of pebbles strongly cemented together with calcareous
matter, which adhered as closely to it as the corre-
sponding matrix did to the associated fossil remains.
The tooth was as completely fossilized as the remains
of the mylodon, megatherium, and scelidothere, and
was so far decomposed that in the attempt to detach
the adherent matrix it became partially resolved into
its component curved lamellae. Every point of com-
parison that could be established proved it to differ
from the tooth of the common Zyguus caballus only in
a slight inferiority of size.

“The second evidence of the coexistence of the
horse with the extinct mammals of the tertiary epoch
of South America reposes on a more perfect tooth,
likewise of the upper jaw, from the red argillaceous

mal. They are five in number on each side of the upper jaw,
and, probably, four on each side of the lower. They present a
more or less tetragonal figure, and have the grinding surface
traversed by two transverse angular ridges.” —Owen.,

il

IN SOUTH AMERICA. 109

earth of the Pampas at Bojada de Santa Fé, in the
Province of Entre Rios. This tooth agreed so closel y
in color and condition with the remains of the masto-
don and toxodon, from the same locality, that I have
no doubt respecting the contemporaneous existence of
the individual horse of which it once formed part.
This tooth is figured at Plate xxxii, F igs. 13 and 14,
from which the anatomist can judge of its close corre-
spondence with a middle molar of the left side of the
upper jaw.

“This evidence of the former existence of a genus
which, as regards South America, had become extinct,
and has a second time been introduced into that conti.
nent, is not one of the least interesting points of Mr.
Darwin’s paleontological discoveries.” *

* Mr. Darwin, in his work on “The Descent of Man” (vol. i,
pp. 280-1), says: “ Although the gradual decrease and final ex-
tinction of the races of man is an obscure problem, we can see
that it depends on many causes, differing in different places and
at different times. It is the same difficult problem as that pre-
sented by the extinction of one of the higher animals—of the
fossil horse, for instance—which disappeared from South Amer-
ica, soon to be replaced, within the same districts, by countless
herds of the Spanish horse.”

In his “Journal of Researches” (pp. 180-1-2), Mr. Darwin
gives further information concerning the fossil teeth described
by Prof. Owen, and advances a theory of the introduction of the
horse into the “so-called New World.” He says: “In the Pam-
pean deposit of the Bojada I found the osseous armor of a gigan-
tic, armadillo-like animal, the inside of which, when the earth
was removed, was like a great cauldron. I also found teeth of
the toxodon and mastodon, and one of a horse, in the same
stained and decayed state. The latter greatiy interested me, and
I took scrupulous care in ascertaining that it had been im-
bedded contemporaneously with the other remains ; for I was
not then aware that among the fossils from Bahia Blanca there

110 FOSSIL HORSES’ TEETH.

Prof. Thomas H. Huxley says (“Critiques and Ad-
dresses,” pp. 191-5):

“Let us endeavor to find some cases of true linear
types, or forms which are intermediate between others,
because they stand in a direct genetic relation to them.
It is no easy matter to find clear and unmistakable
evidence of filiation among fossil animals. After much

was a horse’s tooth hidden in the matrix; nor was it then known
with certainty that the remains of horses were common in North
America. Mr. Lyell has lately brought fr6m the United States
a tooth of a horse; and it is an interesting fact that Prof. Owen
could find in no species, either fossil or recent, a slight but pecu-
liar curvature characterizing it, until he thought of comparing
it with my specimen found here. Certainly it is a marvelous
fact in the history of the Mammalia, that in South America a
native horse should have lived and disappeared, to be succeeded
in after ages by the countless herds descended from the few in-
troduced by the Spanish colonists! (1 need hardly state here
that there is good evidence against any horse living in America
at the time of Columbus).

“When America, and especially North America, possessed its
elephants, mastodons, horse, and hollow-horned ruminants, it
was much more closely related in its zodlogical characters to the
temperate parts of Europe and Asia than it now is. As the
remains of these genera are found on both sides of Behring’s
Straits and on the plains of Siberia, we are led to look to the
northwestern side of North America as the former point of com-
munication between the Old and the so-called New World. And
as so many species, both living and extinct, of these same genera
inhabit and have inhabited the Old World, it seems most prob-
able that the North American elephants, mastodons, horse, and
hollow-horned ruminants migrated—on land since submerged
near Behring’s Straits—from Siberia into North America, and
thence—on land since submerged in the West Indies—into
South America, where for a time they mingled with the forms
characteristic of that southern continent, and have since become
extinct.”

y - .
|

HIPPARION AND ANCHITHERIUM. lil

search, however, I think that such a case is to be made
out in favor of the ‘horses. The modern horse is rep-
resented as far back as the latter part of the Miocene
epoch; but in deposits belonging to the middle of that
epoch its place is taken by two other genera, Hipparion
and Anchitherium. <A species of Anchitherium was
referred by Cuvier to the Paleotheria. The grinding
teeth are in fact very similar in shape and in pattern,
and in the absence of any thick layer of cement, to
those of some species of Paleotherium. But in the
fact that tlrere are only six full-sized grinders in the
lower jaw, the first premolar being very small; that the
anterior grinders are as large as or rather larger than
the posterior ones; that the second premolar has an
anterior prolongation, and that the posterior molar of
the lower jaw has, as Cuvier pointed out, a posterior
lobe of much smaller size and different form, the den-
tition of Anchitherium departs from the type of the
Paleotherium and approaches that of the horse. The
skeleton of Anchitherium is extremely equine.

“Tn the Hipparion the teeth nearly resemble those
of the horse, though the crowns of the grinders are not
so long. Like those of the herse, they are abundantly
coated with cement. In the modern horse, finally, the
crowns of the grinding teeth become longer, and their
patterns are slightly modified.”

Alfred Russel Wallace, F.R.G.S., &c., says (“The
Geographical Distribution of Animals,” New York
edition, vol. i, p. 135):

“OUngulata.—The animals belonging to this order
being usually of large size and Seoactiacd to feed and
travel in herds, are “fable to wholesale destruction by
floods, bogs, precipices, drought, or hunger. It is for

112 FOSSIL HORSES.

these reasons, probably, that their remains are almost
always more numerous than those of other orders of
mammalia. In America they are especially abundant.

“The true horses are represented in the Pliocene by
several ancestral forms. ‘ihe most nearly allied to the
modern horse is Phohippus, consisting of animals
about the size of an ass, with lateral toes not exter-
nally developed, but with some differences of dentition.
Next come Protohippus and, Hipparion, in which the
lateral toes are developed, but are small and function-
less, Protohippus being only two feet and a half high.
Then we have the allied genera, Anchippus, Merychip-
pus, and Hyohippus, which were still smaller animals.
In the older deposits we come to a series of forms, still
unmistakably equine, but with three or more toes used
for locomotion, and with numerous differentiations in
form, proportions, and dentition. In the Miocene we
have the genera Anchitherium, Miohippus, and Meso-
hippus, with three tees on each foot, and about the
size of a sheep or large goat. In the Eocene of Utah
and Wyoming we get a step further back, several spe-
cies having been discovered about the size of a fox,
with four toes in front and three behind. ‘These form
the genus Orohippus, and are the oldest ancestral
horse known.”

The following account of a horse’s tooth that was
found while digging a well is from Zhe Popular Science
feview: ’

“Tn a paper read before the St. Louis Academy of
Science, and reported in The American Naturalist for
March, 1871, Mr. G. C. Broadhead records some in-
teresting facts about fossil horses. Alluding to the
fact that horse remains have been found in the altered

7) te
~$ .
-

A TOOTH FOUND IN DIGGING A WELL. 113

drift of Kansas, he says he is now able to announce
that similar remains have been discovered in a well at
Papinville, Bates County, Mo. Mr. O. P. Ohlinger,
while digging a well, unearthed a tooth at a depth of
thirty-one feet from the surface; it was resting in a
bed of sand beneath a 4-inch stratum of bluish clay
and gravel. Beneath the sand containing the tooth
was a gravel-bed five feet in thickness. He sent the
tooth to Prof. Joseph Leidy, of Philadelphia, who pro-
nounced it to be the last upper molar of a horse, prob-
: ably an extinct species.”

In various volumes of the “ Proceedings of the Acad-
emy of Natural Sciences of Philadelphia,” accounts of
many other fossil horses’ teeth may be found, of which
the following is a specimen (“ Proceedings,” &e., 1871,
p. 113):

“Prof. Joseph Leidy exhibited a specimen of an
upper molar tooth, which Mr. Timothy Conrad had
picked up from a pile of Miocene mar! at Greenville,
Pitt County, N.C. He believed, from its size and the
intricacy in the folding of the enamel of the islets at
the middle of the triturating surface, that the tooth
belonged to the Post-Pliocene Eques complicatus, and
was an accidental occrpant of the Miocene marl. It
might, however, belong to a Hipparion of the Miocene
period, but the imperfection of the specimen at its in-
ner part prevented its positive generic determination.”

The discoveries of horse remains since 1880 by Prof.
E. D. Cope, one of the editors ef The American
Naturalist,.are of an extraordinary character, and an
interesting account of them appears in the APPENDIX
to this work. Truly the Americas are rich in fossil

114 BIRDS WITH TRUE TEETH.

remains, and it is becoming a common thing to hear
of the unearthing of mastodons, elephants, ete.

Note.—The birds of the present epoch are entirely desti-
tute of true teeth, and the mandibles have generally more or
less trenchant, unarmed linear edges; but sometimes they are
armed with processes of bone simulating teeth, but in no other
respect entitled to that name. In former epochs, however,
there existed types actually provided with true teeth, having
all the structural characteristics of those organs, and fitting in
sockets in the jaws. These have been combined by Marsh
under the general term Odontornithes (toothed birds).— Gill.

The teeth of Hesperornis were covered with smooth enamel,
terminating upward in conical pointed crowns and downward
in stout roots. The young tooth probably formed on the inner
side of the root of the tooth in use, a pit for its reception being
gradually made by absorption. The old tooth, being progres-
sively undermined, was finally expelled by its successor, the
number of teeth thus remaining unchanged. The teeth were
implanted in a common alveolar groove, as in lchthyosaurus.
The skeleton measures about 6 feet from the point of the tail to
the end of the bill. Hesperornis regalis appears to have had 14
functional teeth in the upper and 33 in the lower jaw.— Warsi.

A fossil is the body or any known part or trace of an animal
or plant buried by natural causes in the earth. The molds of
shells, the impressions left by the feet of animals in walking,
implements of stone or metal, and other works of human art
which have been accumulated naturally into rubbish-heaps,
are thus strictly fossils. Perhaps the marks of rain, wind,
waves, and shrinkage through heat should be included. * * *
Fossils indicate the former existence of organic races now
entirely extinct ; that, as a whole, each successive period con-
tained more highly organized structures than its predecessor ;
that tropical forms once flourished in the polar regions; that
each epoch was ¢haracterized by peculiar groups. Hence, for-
mations are identified in new countries by means of fossils.—
C. H. Hitchcock.

For interesting articles on Fossil Botany, Fossil Fishes,
Fossil Footprinis, and Fossil Forests, the reader is referred to
Johnson’s ‘‘ New Universal Cyclopedia,” vol. ii, pp. 281-9.

CHAPTER. VI.

DENTAL CYSTS AND SUPERNUMERARY TEETH.

Teeth growing in various parts of the Body.—Some Cysts more
Prolific than others, Producing a Second, if not a Third,
“Dentition.”—Reports and Theories of Scientific Men.—
Cases of Third Dentition in Human Beings.

THE development of abnormal teeth in different
parts of the body (the human body as well as those of
the lower animals, particularly the horse), is not the
least interesting feature in the study of dental science.
To judge from the reports that follow, one would think
the tooth-substance im some horses was an unknown
quantity. It would be interesting and useful to know
whether in such cases the natural teeth are jn a per-
fectly healthy state, and whether the temperature is
natural, instead of being increased, as during certain
periods of teething. While the study of these teeth
may not be of paramount importance, it serves to
further illustrate the physiological relations of the den-
tal system, and ought to assist the surgeon in more
correctly diagnosing diseases.

Surgeon George Fleming, of the Royal Engineers,
contributed a valuable paper entitled “ Dental Cysts,
or Tooth-Bearing Tumors,” to “The Veterinarian” for
1874 (p. 692), the substance of which is as follows:

“In The*Gazetta Medico- Veterinaria of Milan for
1873 (p. 274), Profs. Lanzillotti-Buonsanti and Gui-

116 DENTAL OYSTS.

seppe Generali, of the Veterinary School of that city,
published a most complete and interesting contribu-
tion to our knowledge of the pathology of dental cysts
in the horse, well illustrated with wood-cuts, and in-
cluding a full bibliographical record and synoptical
table of these morbid productions, From their re-
searches it would appear that dental cysts were first
described by Mage Grouillé, in 1811.*

«These teeth- bearing tumors have received different
names. Thus they have been designated ‘erratic’ or
‘misplaced teeth, ‘dental neoplasies,’ ‘odontocysts,’

‘dental deena of the temporal bone,’ ‘ temporal
fistula,’ AN eee development of teeth in unusual
places, ‘auricular teeth,’ ‘odontocele,’ and ‘dentiger-
ous cysts’ or ‘teeth tumors.” They may be developed
in unusual places, such as the temporal region, the
frontal bones, the base of the ear, the space between
the branches of the lower jaw, the lumbar region, the
testicles, and the ovaries. Coleman stands alone in his
case of a cyst found beneath the right kidney, in which
were two small molars and an incisor, attached to a
bone that resembled a jaw, though the Milan profes-
sors believe the teeth in this instance may have been
developed in a testicle retained in the abdominal cay-
ity. The most common situation is undoubtedly in
the temporal region, as in seventy-five recorded Cases
sixty-eight were observed there. These cases all refer
to the horse. Berger-Perriere, however, found a tem-
porary incisor in a fistulous wound near the right ear

* “No mention is made of the Aldoryevouévoi év totic yvadoic, or
maxillary exostoses of Apsyrtus (‘ Hipp. Gr.’ p. 64), who recom-
mends that these tumors should be carefully and completely
removed, or they will return of a larger size.”

The reference note is aiso Surgeon Fleming’s.

~~ ae i

A CYST MISTAKEN FOR GLANDERS. 117

of a lamb two months and a half old (‘Recueil de
Méd. VétérinMire,’ 1835, p. 586).

“Tn most instances only one tooth is found. Gurlt
was the first to find, on the mastoid process of the
temporal bone, a mass of molar teeth fused, as it were,
together. The tumor was three inches and a half
high, and about two in its largest diameter. The horse
had been destroyed for glanders. Goubaux found two
at the posterior portion of the sphenoid bone, and Bay
four. In a cyst of the testicle Gurlt discovered six
teeth, three separate and three in a mass. Bay at-
tended a horse in 1860 that appeared to be suffering
with encephalitis. It died twenty-four hours after his
visit. It had always shown, on the right temporal re-
gion, a tumor without.a fistula, but it did not attract
notice, as it apparently caused no inconvenience. Nine
years afterward, when Bay was preparing the head as
a pathological specimen, he discovered this supposed
exostosis to be constituted by the union of four molar
teeth. The two superior teeth projected from the
temporal articulation, and the inferior two were situ-
ated in the petrous portion of the temporal bone, in-
clining obliquely from within outward. The posterior
portion of the latter projected in a very salient manner
at the se’la turcica, and must have produced much
pressure on important parts of the brain.

“ Age does not appear to have any influence on the
development of these cysts, the animals in which they
have been observed ranging in age from eight or nine
months to fifteen years. The period of formation also
varied greatly. In regard to the side of the body in
which they were developed, in seventeen cases they
were on the left, and in thirteen on the right. In
fourteen cases observed by Macrops, they were indiffer-

118 DENTAL CYSTS.

ently on both sides. In this respect clinical observa-
tion has not yielded any fact of practicak importance.

“ Sometimes, after the extraction of a tooth, it hap-
pens that the cavity of the cyst or the bottom of the
fistula does not cicatrize. This is a sure indication
that a new tooth isforming. Rodet noted this fact as
long ago as 1827. Macrops has observed a case of this
kind. He was compelled to operate twice within three
months, each time removing a molar tooth; and when
he made his report, in 1860, it was probable that a
third tooth was being developed, as the fistula had not
closed.”

Surgeon Fleming also mentions cases that were ob-
served by Surgeons Perosino, Martin, Harold, Gamgee,
Coclet, Lafosse, and others. He continues:

“Profs. Lanzillotti-Buonsanti and Generali made
minute inspection of a specimen of tooth taken from
the bas2 of the ear of a foal twenty months old, and
they report that microscopically the structure of such
teeth does not differ much from natural teeth. The
same constituents—dentine, enamel, and cement—
were found, the only difference being that they were
arranged in an unusual manner. In the tooth they
examined, for instance, the cement was abundant in
the central part, while in that studied by Oreste and
Falconio, the dentine was most abundant and the
cement least in quantity.” ;

Surgeon Fleming next refers to and gives a sum-
mary of the views of scientific men, who say that “A
certain number of teeth may sometimes be developed
as parasitic productions in a cavity similar to and situ-
ated near the mouth (in which category is included

r ‘ae
=

A FETUS WITHIN A FETUS. 119

the excellent case occurring in a woman, and de-
scribed, in 1862, by Prof. Generali—an observation
unique in the teratology of mankind—namely, a
case of parasitic monstrosity, in which, bowever, the
designation ‘dental cyst, so inexact in itself, 1s in-
appropriate and false);” that “tbe ovarian cysts in
women, in which have been found pieces of bone and
cartilage, teeth, and a lower jaw, more or less de-
formed, ought to be considered as probable cases of
ovarian impregnation with an incompletely developed
fetus, and in young girls as examples of the intra-
uterine formation of a fetus within a fetus;” that
“only in this way can be explained the lipomatous
and sarcomatous congenital masses contained in cysts,
with the teeth and fragments of bone simulating an
incomplete jaw, which have been obseryed on the
human orbit (Lobstein and Travers), on the palate
(Otto), on the tongue (Stansky), on the side of the
jaw, in the cheek, and on the neck, but which Schultze
and Panum consider as the simple proliferation of em-
bryonic plasmatic cells;” that “some dental cysts are
true dermoid cysts, containing hair and teeth,” Xc.,
and closes his paper with the following common-sense
suggestion :

“Perhaps direct researches, which have not yet been
made, carried out in favorable circumstances, will bet-
ter serve in deciding their real nature than all the
more or less brilliant academical reasoning.”

John Gamgee, Professor of Anatomy and Physiology
in the Edinburgh Veterinary College, in the course of
a series of articles on various subjects in “The Veter-
inarian” for 1856, thus comments on a case of dentig-
erous cyst, the history of which was originally written

120 DENTAL CYSTS.

by Monsieur Lafosse and published in the “Journal
des Vétérinaire du Midi:”

“MM. Lafosse, Professor of Clinical Medicine in the
Veterinary School of Toulouse, had under his treat-
ment a four-year-old mare that for two months before
admission into the infirmary was affected with a phleg-
monous tumor in the region of the left ear. This was
opened. The wound that resulted rapidly contracted,
but a fistula remained. When Lafosse first saw the
case, he found a painful tumor, with a granulating
wound just behind the scutiform cartilage, and near
the upper part of the parotid gland. By probing he
ascertained that ab the bottom of the fistulous tract
was some hard substance, which he supposed to be the
seutiform cartilage in an ossified state, or a portion of
the temporal bone exfoliating. A severe operation
was performed, end the solid substance extracted. It
was double, deeply seated, and firmly adherent to sur-
rounding textures. Slight hemorrhage ensued from

he division of the anterior auricular, but was easily
stopped. The wound. was dressed, and the animal
soon recovered, having shown only a few symptoms of
sore throat after the operation.

“J shall not translate M. Lafosse’s description of
the products he extracted. They were composed of
tooth-substance, and although it has been questioned
whether it is real teoth that is developed in the shape
of accidental growths in the region of the ear, still the
fact is now well established, however puzzling to the
minds of some it may be to comprehend their origin.

“Tafosse attempts a teratological explanation, but
asks: ‘If teeth are looked on as arising from the tegu-
mentary system, considering them in most animals ag

TEETH EMANATING FROM OSSEOUS SYSTEM. 121

emanating from papillee and mucous membrane, where
was the dermoid papilla that constituted the basis of
development of this tooth, deeply seated and close to
the ear, especially as what might be taken as the
crown looked toward the inner surface of the skin ?’

“Further on Lafosse shows that in certain animals
teeth absolutely emanate from the osseous system, as
in the colwber scaber and other serpents, in which true
osseous eminences, coated by enamel, pierce the esoph-
agean tunics, and project into the tube; they are at-
tached to about thirty vertebrae, of which they form
the inferior spinous process. These are intended to
crush the eggs that the serpents feed upon.

“ Having established the fact that teeth may spring
from bone as well as mucous membrane, Lafosse leads
us, where we never suspected, to consider the dental
tumors above spoken of as congenital, and he looks
on them as having sprung from some rudiment of a
maxillary bone. In a word, he looks on the abnormal
tooth in question—without offering any plausible ex-
planation—as an aberration in development. He does
not class such teeth with the teeth formed in the
ovary, &c., but rather with those instances where an
extra limb or portion of an extremity is to be met with.
It is an accidental excess of parts in an otherwise well-
formed body. ‘It cannot,’ says Lafosse, ‘be looked on
as an osseous transformation of certain tissues.’

“T have spoken of the case at length, for surgically
it is of the very greatest interest. As pathological
anatomists, it is our duty to study the laws of disease
as well as health. It is praiseworthy to dive into the
mysteries of the origin of monsters, but it is essential
to adhere to facts and not sacrifice them to theoretical
explanations.

6

122 DENTAL CYSTS.

“Tn common with others, I have studied several of
these dental tumors. They may spring from several
of the bones of the head, but especially from the region
of the petrous temporal bone. ‘They may project to-
ward the interior of the cranium, but they more fre-
quently project outwardly. They may be strongly
implanted in the bone, or get separated; then they
are maintained in their situation by the soft textures
around. Their development is not more extraordinary
than that of other osseous growths that spring from
the cranial or maxillary bones; and their tooth-formed
structure (teeth in the region of teeth), is not more
wonderful than bony tumors in other parts of the sys-
tem, whether connected or not with the skeleton.”

Prof. William Sewell, President of the British Vet-
erinary Medical Association, at the meeting of that
body on May 15, 1838, advanced an interesting theory
of the growth of abnormal teeth. It may be true, for
after the teeth have attained their full growth, it is
reasonable that the dental arteries are less active. But
as the teeth continue to grow throughout life, a fact
Prof. Sewell does not mention, it is not so reasonable
that they even “in a manner cease” to act. The pro-
fessor’s remarks are thus reported (“ Veterinarian,”
1838, “ Proceedings Vet. Med. Ass.,” p. 199):

“'The President begged leave to direct the attention
of the meeting to a horse’s tooth that had been pre-
sented to him. It was a fine specimen of the anomaly
occasionally observed in the dental system of the horse
—the production of teeth in other places than the
alveolar cavities, after the natural teeth had been per-
fected. The situations which Nature in her wander-
ings selected were occasionally very singular. He had

TEETH LIKE A CALF’S YOUNG HORN. 123

seen a tooth which grew from the petrous portion of
the temporal bone, like a young horn frum the fore-
head of a calf. It formed a hard and seemingly very
painful tumor, which was ultimately opened, and the
bony substance, which proved to be an alinost perfect
tooth, extracted. He had seen three or four similar
cases in which teeth had been thus produced. When
the dental arteries in a manner cease to act—the teeth
having attained their full growth—there was a singu-
lar predisposition in the neighboring arteries to take
on the same action, and teeth, more or less perfect,
were formed in parts altogether unconnected with den-
tition. In this case there were two, one on either side
of the forehead.”

Surgeon F. Denenbourg makes a detailed report in
“The Veterinarian” for 1869 (p. 533) of six cases of
dental cyst, five of which he operated on successfully.
The first case he treated was in 1837. He confesses
that he believed them to be mucous tumors till 1851,
when he found a molar tooth perfectly formed. This
tooth, which was deposited in an anatomical museum,
was as large as a pigeon’s egg, and had three roots.

Surgeon C. C. Grice, of New York, makes the fol-
lowing report (“ Veterinarian,” 1867, p. 392):

“ Whether the case the facts of which I am about to
communicate will prove of sufficient interest to be pre-
sented to the notice of the veterinary profession, or
will add anything to the advancement of veterinary
pathology, I know not; yet I would be glad to see it
inserted in our respectable old journal, ‘'The Veteri-
narian,’ for d hold it to be the duty of every member
of the profession to advance its interests to the best of

124 DENTAL CYSTS.

his ability. I send it because to me it is a very rare
case. I have now been in practice more than forty
years, and I have not met with anything of the kind
before.

“ At the request of Mr. Barnum, a merchant of our
city and the owner of a breeding-farm in Westchester
County, I attended a two-year-old colt, considered to
be very valuable, as he comes from trotting stock. Mr.
Barnum merely said the colt had a discharge from the
base of the near ear, and that it had existed for ten
months.

“T found the animal so very shy on account. of the
previous torturing of his attendants, that I could not
approach him; therefore I had to cast him. The in-
troduction of the probe failed to satisfy me that any
foreign body existed there; but on dilating the orifice
and introducing the most reliable of all probes, my
forefinger, I discovered a hard substance, which was
firmly attached to the temporal bone and surrounding
parts. I could not grasp the substance with the for-
ceps, therefore I used the handle of the instrument as
a lever, and after using great force dislodged it. Mr.
Barnum picked up something in the grass four or five
yards from me, and it proved to bea molar tooth. On
examining the wound afterward I found some loose
fragments of bone, and on removing them they ap-
peared to be the socket of the tooth.

“J would have sent you a report of this case earlier,
but I was desirous of seeing its termination. Mr. Bar-
num says the parts have entirely healed and left no
blemish.”

Prof. William Williams advances an interesting the-
ory regarding the cause of dental cysts, and also the

as ae se ae
= +. Pe
.

AMAUROSIS AND ATROPHY OF THE EYES. 125

manner of their formation. He says (“ Principles and
Practice of Veterinary Surgery,” p. 412):

“Cysts containing teeth have been found in the tes-
ticles and other parts of the body, but those which are
of importance to practical men are found within the
antrum. I have seen several cases of this kind, and
have extracted teeth from cysts even so high as the
base of the ear.

“During life these tumors are distinguishable by
more or less disfigurement of the face, by a bulging out
of the superior maxillary bone, accompanied in some
cases by amaurosis of one eye, succeeded by atrophy
of the eye from the pressure of the growing tumor.
In other cases these complications are not present, but
now and then an abscess forms in the post-orbital re-
gion, wnich will be found on examination to contain a
hard body—an imperfect tooth.

“To understand the process by which these tumors
are formed, it is necessary to remember that the teeth
of all animals belong to and arise from the membran-
ous portion of the digestive canal, and that at a very
early period of fetal life a provision is made for the
development of- the permanent teeth as well as the
temporary. ‘This provision, according to Goodsir, is
as follows: ‘ As early as the sixth week of intra-uteral
life (human), a groove appears along the border of the
future jaws, called the primitive dental groove, which
is lined by the membrane of the mouth. At the bot-
tom of this groove projections—papille—spring up,
corresponding in number with the temporary teeth.
While the growth of the papille is going on, partitions
are formed across the grooves, by which they become
separated from each other. These partitions subse-

126 DENTAL CYSTS.

quently form the bony sockets, thus placing each
papilla in a separate cavity. Concurrent with this
process, small growths take place upon the membrane
of the mouth, just as they dip into the papillary cavity
or follicle, which finally, by union with other growths,
form a lid which covers the papillz in a closed sac or
bag. Before the final closing of the follicle, a slight
folding inward of its liming membrane takes place.
This inward folding of the membrane of the primitive
groove is for the purpose of forming a new cavity—the
cavity of reserve—which furnishes a delicate mucous
membrane for the future formation of the permanent
teeth. The cavity in which the permanent tooth is
developed is a mere detachment from the lining of the
primitive groove, and in it a papilla is formed in the
Same way as that of a temporary tooth.’ *

“ Now, I look on the formation of these tumors as
being due to some irregularity in this folding of the
lining membrane, by which the ‘cavity of reserve’ is
made up of several folds; that these folds eventually
become separated, forming separate cavities of reserve,
and that a papilla similar to those of the natural teeth
is developed in each cavity. These irregular papille
are converted into irregular teeth, which, for want of
space in the mouth, are forced into the antrum, and
may completely block it up, as well as the posterior
nasal opening.

“T have classified them as cystic tumors, as at first
they are inclosed in sacs or cysts. They soon burst
through their investing membrane, however, and form
a large tumor, composed entirely of teeth, having a

* Compare Professor Goodsir’s theory with those advanced
by Messrs. Owen, Tomes, Chauveau, and others in the first
chapter.

a .

A BULL WITH AN UPPER INCISOR. 127

great variety of shapes, and running in different direc-
tions. The teeth vary in size, some being very small,
while others are nearly as large as a permanent grinder.
Hach tooth has a pulp cavity, and is composed of the
same substances as the natural teeth. Should their
removal be desirable, it will be necessary to trephine
the superior maxillary sinus and detach them with the
forceps.” '

In the chapter entitled “The Pathology of the
Teeth” (the VIII.), Surgeons Bouley and Ferguson,
in the course of their memoir on horses’ teeth, record
some important facts about supernumerary teeth. In
one animal the rows of grinders are said to appear
double. The facts are given in that particular chap- -
ter in preference to the present one in order that the
memoir may have a connected reading.

M. Roche Lubin gives the following account of a
tooth that he extracted from the upper jaw of a young
bull (“ Le Zooiatre du Midi,” February, 1838):

“On the 14th of April, 1837, I was requested by M.
Bonhome, who lives near Rhodez, to extract a tooth
which was growing in the middle of the palate of his
young bull. The novelty of the thing made me hasten
to comply with his request. The animal being secured,
T removed the tooth in the usual way. <A very consid-
erable hemorrhage followed its extraction, which was
performed with some difficulty on account of the tooth
being firmly implanted in the palatine arch. It was
situated at the middle of the median line, and was of
precisely the same character as that of the usual incisor
tooth of the ox. This is, I believe, the only case on
record, the incisor teeth being wanting in the upper
jaw of cattle.”

128 SUPERNUMERARY TEETH.

Human beings, like the lower animals, are now and
then afilicted with a superfluity of tooth-substance, or
at least they have supernumerary teeth. John Hunter
says (“The Human Teeth,” p. 53):

“We often meet with supernumerary teeth, and this,
as well as some other variations, happens oftener in
the upper than in the lower jaw, and, I believe, always
in the incisors and cuspidati. I have only met with
one case of this kind, and it was in the upper jaw of a
child about nine months old. The bodies of two
teeth, in shape like the cuspidati, were placed directly
behind the bodies of the two first permanent incisors;
so that there were three teeth in a row, placed behind
one another, namely, the temporary incisor, the body
of the permanent incisor, and that supernumerary
tooth. The most remarkable circumstance was that
these teeth were inverted, their points being turned
upward and bent, caused by the bone which was above
them not giving way to their growth, as the alveolar
process does.”

The following account of cases of third dentition in
‘human beings is from “ Bond’s Dental Medicine”
(p. 216):

“Third Dentition.—A number of well authenticated
cases of partial and even complete dentition, occurring
in very old persons, are recorded in the books. In one
instance, given in the ‘Edinburgh Medical Com.’ (vol.
iii.), the patient, who was sixty years old and entirely
toothless, suffered very severely. At the end of twenty-
one days from the beginning of his sufferings, however,
he was compensated by the appearance of a complete
set of new teeth.

> an ee
{Ss -

i

THIRD DENTITIONS FATAL. 129

“With regard to the constitutional effects of this
abnormal dentition, Prof. Harris, who relates two
cases as having occurred under his own observation,
says: ‘It seems that the efforts made by nature for the
prcduction of a third complete set of teeth are usually
so great that they exhaust the remaining energies of
the system, for occurrences of this kind are generally
soon followed by death.’ ”

RETENTION OF Decipuots TEETH.—Miss A. B.,
aged twenty years, has never shed her deciduous
second molars. ‘They are sound and healthy, except
one. The first bicuspids have been erupted; the
second have not. Would it be proper to extract the
temporary teeth?—M. A.

In answer to M. A., in the November, 1881, num-
ber of the Dental Cosmos, I would reply that from
my experience it would be poor practice to extract
healthy deciduous molars at that age, merely because
they were deciduous, and when nothing else indicated
such treatment. I have met with many such cases.
Sometimes only one or two of the molars are retained ;
at other times three or four. I know of two sisters,
over forty years of age, who have each their four
deciduous second molars, and every one perfectly
health y.— Stormont.

CHAPTER VII.
HORSES’ TEETH UNDER THE MICROSCOPE.

The Dentinal Tubes, Enamel Fibers, and Cemental Canals De-
scribed and Contrasted.

Pror. RrcHARD OWEN’Ss description of the micro-
scopical appearance of horses’ teeth, like the extracts
already made from his works, is both interesting and
profound. The teeth described are illustrated in the
second volume of the “ Odontography,” the section of
the molar being magnified three hundred linear diam-
eters; that of the incisor, however, is not magnified.
In the first volume (pp. 576-7-8) Prof. Owen says:

“The body of the long molar teeth of the horse.
consists of columns of fine-tubed, unvascular dentine,
coated by enamel, which descends in deep folds into
the substance of the teeth. The enamel is covered
by cement, thickest in the interspaces of the inflected
enamel-folds and upon the crowns of the molars, where
it is permeated by vascular canals, thinnest on the
crowns of the canines and incisors. At the roots of
these teeth, and on those developed from the worn-
down molars, the dentine is immediately invested by
cement.

“In a vertical section of the incisor, as in Plate 136,
Fig. 11, the pulp-cayity, contracting as it approaches

TUBES DICHOTOMOUSLY BRANCZIED. 151

the vertical enamel-fold, divides near the end of that
fold, and extends a little way between it and the
periphery cf the incisor, or leaves a few medullary
canals and a modified thin tract of irregularly formed
dentine between the reflected and the outer coat of
enamel, but rather nearer the former. Above this
tract, near the summit of the crown, the dentinal tubes
proceed in a nearly vertical direction, with a gentle
sigmoid primary fiexure, where they diverge from the
perpendicular. Lower down they diverge in opposite
directions, curving from the remains of the pulp-
fissure toward the outer and the inner enamel, and are
described by Retzius as being in the form of the Greek
€; but the course of two distinct series of dentinal
tubes, and not of a single tube, is illustrated by this
comparison. When the pulp-cavity comes single and
central, as at the lower half of the tooth, the tubes
diverge to the periphery, with one principal primary
curve, convex toward the crown. Each tube is bent
in minute secondary gyrations to within a short dis-
tance of its peripheral termination, where it is much
diminished in size, and is dichotomously branched.
The tubes at their beginning form the upper calcified
tracts of the pulp-cavity, which usually retain some
remnants of that vascular receptacle in the form of
medullary canals, and are strongly and irregularly
flexuous before they fall into the ordinary primary
curves. These tubes, proceeding toward the inner
reflected folds of enamel, are more vertical than the
tubes going to the periphery.

“ A transverse section of the incisor of a young horse
or ass, taken across the part marked a in Fig. 11, shows
a long ovak island of vascular cement in the center,
bounded by a border of enamel, with an irregular cre-

132 HORSES’ TEETH UNDER THE MICROSCOPE.

nate edge next the cement, and an even edge next the
dentine, which is here clearly seen to be divided into
an inner and an outer tract by an irregular series of
the vascular canals continued from the summit of the
pulp-cavity, and by the irregularly tortuous dentinal
tubes, which, with tie canals, indicate the last con:
verted remnant of the pulp in this part of the crown.
The inner tract of dentine next the island of enamel
is well defined, and a little broader than the secretion
of the enamel itself, and shows the extremities of the
tubes cut transversely, which, as before observed, were
at this point directed chiefly in the axis of the incisor
toward the working surface of the crown. The tubes-
in the outer tract of dentine, inclining more toward
the sides of the tooth, are more obliquely divided, and
at the ends of the section they are seen lengthwise, ele-
gantly diverging toward the sides of the section. This
tract of dentine is bounded externally by a layer of
enamel, one-sixth part thicker than that forming the
-central island; and the enamel is coated by an outer
layer of cement, of its own thickness at the sides, but
thinning off at the two ends of the section. The den-
tinal tubes proceeding from the residuary pulp-tract
make strong and irregular curvatures, diverging to
include the divided areas of the vascular canals, and
in the outer layer, at one side of the section, they de-
scribe strong zigzag curves at the middle of the outer
division of the dentine.

“The diameter of the dentinal tubes at their central
and larger ends is pretty regular, about gj45th of an
inch; at the middle of their course, zJ5;th of an inch,
thence decreasing, and very rapidly, after the terminal
bifurcations begin. The tubes are separated from one
another by intervals varying between once and twice

— %
: , To? ‘ .
ft -

‘.

-

THE CURVES OF THE DENTINAL TUBES. 133

their thickness. In some parts of the dentine of the
incisor they are more closely crowded together, espe-
cially near their origin from the pulp-cavity. Their
secondary gyrations describe a curve of about 345th
of an inch in length. These subside in the slender
terminations of the tubes, which bifurcate dichoto-
mously once or twice, and send off small lateral
branches near the enamel. The small lateral branches
are chiefly visible in the peripheral third part of the
tubes, and are sent off at very acute angles, except in
the strongly and irregularly bent origins from the
pulp-tract. I have never seen these small branches of
the dentinal tubes terminating in radiated cells, like
those of cement and bone, as Retzius describes; but
the peripheral smallest branches near the enamel occa-
sionally dilate into corpuscles much more minute
than the radiated cells, as they do in the teeth of most
quadrupeds. }

“The dentine, as seen in a longitudinal section of
the crown of a molar, by a magnifying power of three
hundred linear dimensions, is figured at a, Plate 137.
The tubes are here separated by rather wider inter-
spaces than those of the incisor, and do not decrease
in size so rapidly. The convexity of the terminal bend
of the tubes is turned toward the summit of the crown.
In the incisor, the clear dentinal cells are very small
near the peripheral part of the dentine, but increase in
size as they approach the pulp-cayity. ‘They are of a
sub-circular figure, with bright, transparent lines.

“The central cement in the crown of the incisor is
permeated by vascular canals, separated by intervals of
from two to three times their own diameter, directed
in the middle of the substance in the axis of the tooth,
but diverging like rays obliquely toward its periphery.

134 HORSES’ TEETH UNDER THE MICROSCOPE.

The clear substance forming the walls of the canals is
arranged in concentric layers, the thickness of the
walls being about equal or rather less than the area of
the canal. The radiated cells, generally of a full oval,
sometimes of an angular form, are chiefly dispersed in
the interspaces of the vascular canals, and with their
‘long axis parallel with the plane of the layers of the
coats. The finer system of tubes radiating from the
cells, and corresponding by minute branches from the
vascular canals, freely intercommunicate. In the
peripheral cement of the incisors examined by me, I
found no vascular canals, but only the radiated cells,
and the fine tubuli which I have ealled ‘cemental,’
and which traverse the cement at right angles to its
plane, and communicate with the tubes radiating from
the cells. These are more usually elliptical than in
the thicker central cement, their long axis being par-
allel with the borders of the cement. They are most
abundant next the enamel, and rarely encroach upon
the clear peripheral border of the cement. The exte-
rior coronal cement of the molars (Plate 137, ¢), is as
richly permeated by vascular canals (v v), as is the
central cement of the incisor.

“The enamel-fibers of the horse’s incisor are very
slender, not exceeding twice the diameter of the denti-
nal tubes. They extend, with a single sigmoid curve,
through the entire thickness of the layer, contiguous
fibers curving in opposite directions. The peripheral
border, or that next the cement, is everywhere indented
with hemispherical pits from s$,5th to zggqth of an
inch in diameter, from four to six of the radiated cells
of the cement being often clustered together in the
larger depressions. The inner or dentinal border is
nearly even and straight; here are seen the short

— Hew,
7

CLEARNESS OF THE ENAMEL-FIBERS. 135

cracks or fissures extending into the enamel. The
fibers are rather more wavy in the thicker enamel of
the molar teeth (Plate 137, 4).

“If the enamel is viewed in sufficiently thin sec-
tions it is free from those wavy, dusky markings which
are produced by the more tortuous fibers of the human
enamel; and I have been unable to distinguish any
transverse strie in the fine fibers of that tissue in the
horse. The appearance of such is given by thicker
sections of the enamel-fibers taken obliquely across
them, and is produced by the cut ends of the fibers.”

a

CTA Pere ints ¥ a4.
THE PATHOLOGY OF THE TEETH.

Importance of the Subject.—Caries caused by Inflamed Pulps,
Blows, Virus, and Morbid Diathesis —Supernumerary Teeth
and other Derangements.—Trephining the Sinuses.—Gutta
Percha as a Filling.—Cleaning the Teeth.—A Diseased Fos-
sil Tooth.

THE importance of the study of the pathology of
the teeth is self-evident, for they not only bear impor-
tant relations to the general system, but, like all other
parts of it, are subject to disease and derangement.
The fact that disease of the teeth is involved in more
or less mystery, is an argument in favor of the study
of the subject, for, to use Surgeon Gamgee’s words,
it is a “duty to study the laws of disease as well as
health,” and “it is praiseworthy to dive into the mys-
teries of the origin of” diseases as well as monsters. It
is probably not too much to say that, to the successful
surgeon, knowledge of the diseases and derangements
of the teeth is indispensable.

In order to facilitate the study of and cast light on
the subject, I have brought into juxtaposition, as it
were, a summary of the views of a few able men in
regard to the cause of caries, &c., which, better still, is
followed by the reports of well-known surgeons, who
give the results of their experiences in detail.

DECAY, EXOSTOSIS, AND ABSCESS. 137

Dr. G. A. Mills says that when the tone of a tooth
can be brought to the point of resistance of the in-
flammatory process, dentists will have gone a long
way in providing against the effects of caries. The
dentine decays faster than the enamel.

Prof. Owen says a tooth has no inherent power of
reparation; that in growing teeth, with roots not fully
formed, the cement is so thin that the Purkinjean
cells are not visible. It looks like a fine membrane,
and has been described as the periostenm* of the
roots. It increases in thickness with the age of the
tooth, and is the seat and origin of what are called
exostoses of the roots. These growths are subject to
the formation of abscesses and all morbid aetions of
true bone. Of a diseased fossil horse’s tooth he says:

“But the cavity had evidently been the result of
some inflammatory and ulcerative process in the origi-
nal formative pulp.”

Dr. Boon Hayes says:

“T think it would not be difficnlt to prove that
caries of the teeth more frequently proceeds from in-
flammation beginning im the pulpal cavity than from
any other cause.”

Dr. Robley Dunglison says:

“The most common causes of cariesare blows, the
action of some virus, and morbid diathesis.”

* Surgeon John Hughes says: “The periosteum of the teeth
is not supplied with blood in the way the same membrane in
other parts of the body usually is. It is supplied by meaus of
vessels coming from the pulp of the tooth.” If this is true, then
it would be easy for inflammation ta be conveyed from one to
the other.

138 THE PATHOLOGY OF THE TEETH.

“Odontonecrosis ” is defined by him as “dental gan-
grene,” and “ Odontrypy” as “the operation of perfo-
racing a tooth to evacuate the purulent matter con-
fined in the cavity of the pulp” (pulpal cavity).

Prof. William Percivall, referring to two diseased
grinder teeth (horses’), says:

“They seemed to have been cases which had origi-
nated in internal injury.”

Surgeons Bouley and Ferguson say:

“Tn explaining caries of the teeth, we cannot invoke
the aid of inflammation and the modifications which
it induces in the tissues it attacks; nor can we say
that inflammation implies an active circulatory move-
ment, an afflux of liquid, an alteration, nervous de-
rangement, &c.”

Possibly the gentlemen were not aware of the in-
flammation that Prof. Owen says may exist “in the
original formative pulp,” and of that of “the pulpal
cavity ”—the pulp in the cavity of a full-grown tooth—
mentioned by Drs. Hayes and Dunglison. Are not
such inflammations liable to be produced by colds or
violent shocks ?

Prof. George Varnell, who believes caries of the roots
of horses’ teeth is usually caused by external violence,
Says:

“Inflammation of the alveolo-dental periesteum
would tend to this result (caries of the roots). When
the nutrition of any part of a tooth becomes arrested,
decay is likely to follow. When caries begins from
within, it is due to arrestation of nutrition, arising
perhaps from disease of only a part of the central pulp

.

NATURE’ BARRICADING DISEASE. 139

of the tooth; if from without, it will arise from the
periodontal membrane where it meets the gum.”

- Dr. John Tomes thus describes the conservative ac-
tion of nature (barricading disease, as it were) when a
tooth is affected with caries (* Dental Physiology and
Surgery”):

,

“When a portion of dentine has become dead, it is
circumscribed by the consolidation of the adjacent liv-
ing tissue. The tubes, becoming filled up, are ren-
dered solid, and the circulation is cut off from the dead
mass. ‘This consolidation does not go on gradually
from without inward, keeping in advance of the decay,
but occurs at intervals. It seems that successive por-
tions of dentine lose their vitality, and that the contig-
uous living portions become consolidated.”

Prof. M. H. Bouley and Surgeon P. B. Ferguson are
the joint authors of a memoir on horses’ teeth, which
filis thirty or more pages of “The Veterinarian” for
1844. The substance of the part which relates to the
pathology and dentistry of the teeth is as follows:*

“7. Anomalies in the Number of the Teeth—Some-
times, but very rarely, we meet with supernumerary
grinders in the horse. The anomaly may be caused
by the persistence of the temporary teeth, the develop-
ment of abnormal teeth on one or both sides of the
arcades (rows of teeth), and the cutting of a greater

* The phraseology of Messrs, Bouley and Ferguson’s memoir
has been more or less changed and the matter somewhat con-
densed and rearranged. The surgeons’ golden ideas deserve to
be set forth in clearer and more forcible language than they re-
ceive at their own hands, and it is believed that some improve-
ment has been made.

140 THE PATHOLOGY OF THE TEETH.

number of permanent teeth than should naturally
exist. In the latter case it is necessary to admit the
existence of a greater number of dental bulbs than is
normal. We saw some time ago, at the consultation
of the Veterinary College in Alfort,* a horse which, to
use the words of its owner, ‘had a double row of teeth
in the upper jaw.’

“Sometimes the supernumerary tooth is situated in
one or the other jaw, in front of the normal range of
erinders, without having a corresponding tooth in the
opposite jaw; at other times it is situated either within
or without the arcade. The latter anomaly is caused
more frequently by the deviation of a normal than by
the addition of a supernumerary tooth. In the first
instance it is not long before mastication is interfered
with. The tooth, by its growth, which is not counter-
acted by wear, finally reaches the opposite jaw, lacera-
ting the mucous membrane and contusing and some-
times fracturing the bone itself. In the second in-
stance, the tooth, if within the arcade, is an obstacle
to the tongue; if without, to the cheek. Besides these
evil effects, supernumerary teeth cause irregularity in
the arcades, and consequently prevent the exact appo-
sition of the normal teeth. They interfere also with
the action of the lower jaw. Hence irregularity in the
friction and wear of the teeth follows, the result being
that the performance of the all-important function of
mastication is almost stopped.

“2. Anomalies in the Form of the Arcades.—The
upper rows of grinder teeth form two curves, opposed
by their concavities, while the lower rows form two

* A city of France—Prof. Bouley’s home. Surgeon Ferguson,
an Englishman, was attached to the Paris British Legation.

_ > of) ooh oe " 5 J
«be .
ay
.

DERANGEMENTS OF THE GRINDERS. 141

nearly straight lines, which converge as they descend
toward the symphysis of the chin. These (the curves
and lines) may be, owing, in some cases, to congenital
conformation, very irregular. Sometimes, in fact, the
curves of the upper jaw are effaced; at other times,
and most frequently, the lines of the lower jaw are
incurvated within the upper arcades. The deformities
may exist singly or together. The result is that, in
the approach of the jaws, the relation is not identically
established between the surfaces of friction, and the
result of this, in turn, is an irregularity of wear and an
abnormal development of the borders of the tables (the
crowns of the teeth), within in the lower jaw, without
in the upper.

“3. EHxuberance of particular parts of the Dental
Apparatus.—(A.) The upper grinders are wider than
the lower, so that in order to cause friction in their
entire thiekness, a lateral movement of the lower jaw
is required. Sometimes, perhaps because the move-
ment is not effected throughout the entire limits of
the segment of the circle, the outer borders of the
upper teeth do not wear sufficiently, and therefore
become elevated and sharp. At other times it is the
inner borders of the lower teeth that project. In
the former case the cheeks suffer; .in the latter, the
tongue.

“Tn rare cases the tables, which present a normal
inclination inverse in the two jaws, at length form
planes very oblique. The obliquity is sometimes so
great that the internal borders of the lower teeth are
very elevated, whi'e the external is almost level with
the gums. The inverse effect manifests itself at the
upper jaw. The consequence is that the half-masti-
cated food slips into the pouch of the check.

142 THE PATHOLOGY OF THE TEETH.

“There is in the museum of the College at Alfort a
horse’s head in which this deformity may be seen in
its greatest degree. The tables of the teeth at the right
side form planes so much inclined that they close
together like the blades of shears. As there was no
friction to wear the teeth down, they grew to the hight
of three inches. The fourth and fifth teeth of the
right side of this rare anatomical specimen are absent.
Perhaps they were carious. The rarefied and spongy
tissue of the socket-benes indicate the seat of an alter-
ation—probably caries—which was the point of depar-
ture of the general tumefaction. The last tooth, by
its oblique direction toward the empty sockets, indi-
cates that the loss of the teeth occurred during the life
of the animal, some time perhaps prior to its death.
The defect of the right side doubtless forced the ani-
mal to use the left for the purposes of mastication. In
such cases the teeth that do not wear grow till they
reach their respective opposite jaws, even when those
at the opposite side of the mouth are in exact con-
tact, an anomaly never produced in the normal state.
The function of mastication operates according to the
obliquity of contact, and a parallelism is established
by friction between the tables which normally would
be superposed.

“This appears to us to be the only interpretation of
the facts, and we have observed two analogous exam-
ples in living horses, but we did not think to ascertain
whether the deformity of an entire arcade was owing
to defect of a grinder or to disease of the bone. The
solution of the question would be an important acqui-
sition to the science of dental pathology.

“(B.) There is another kind of deformity of the
arcades not very uncommon. The lower teeth wear

ee phe.
_— — :
? : -

“GUMMING IT.” 143

out more rapidly than the upper, the cause of which
is perhaps owing to the superiority of the latter in size
and strength. The erown surface of the lower rows
is slightly concave, the upper rows slightly convex.
The result is that the lower center teeth are sometimes
worn to their sockets, which renders the mastication
of hard food impossible. At first, however, there is
no interference with mastication, and it is usually only
in old age that the deformity reaches its worst stage.
There is no remedy for the defect, bué tts progress
may be retarded by the use of soft food.*

“(C.) Lack of regularity in the length of the rows
becomes the cause, in horses a little advanced in age,
of a peculiar deformity in the first upper and the last
lower grinders. Generally the upper range passes that
of the lower by some lines, the first upper grinder lap-
ping over; but sometimes the case is the reverse, the
last lower grinder projecting beyond the last upper.
The projecting part of the tooth grows till it reaches
the opposite jaw, when, unless it is filed or chiseled off,
the most serious consequences will follow.

“(D.) When a tooth is entirely deficient, the oppo-
site tooth grows till it fills the void; then, no remedy
being applied, the work of destruction begins. If a
tooth is only partly deficient, no matter whether it be
from fracture, caries, or arrestation of growth, it is
gradually destroyed by the opposite tooth. When it
is the first upper grinder that is deficient, the first
lower acts on the palatine vault like a battering-ram.
‘I have seen,’ says Solleysel (1669), ‘a mule that had a
lower grinder of extreme length, the upper tooth being
absent. The palate was pierced to the thickness of a

* The italicized words are mine.—@,

144 THE PATHOLOGY OF THE TEETH.

finger, which caused the animal great difficulty when
he drank

“4. Cartes of the Teeth.—The grinder teeth of horses’
are more frequently affected with a profound alter-
ation ot their substance than is generally believed.
The disease is cailed Caries; it may not, however, be
strictly analogous to caries of the bones, for the bones
are vascular, while the teeth have neither vessels nor
nerves. Caries of the bones implies an active labor, in
which the vascular apparatus plays an important part.
It isa phenomenon of interstitial suppuration, under
the influence of the inflammation which has set the
capillary system of the organ in play. In explaining
caries of the teeth, however, we cannot invoke the
aid of inflammation and the modifications it induces
in the tissues it attacks; nor can we say that inflam-
mation implies an active circulatory movement, an
afflux of liquid, an alteration, nervous derangement,
&e. If the teeth are living, the laws which govern
their vitality are entirely unknown to us.* How, then,
penetrate into the secrets of the alterations which they
undergo, when the conditions of their normal existence
are enveloped in obscurity? Neither is it possible to
resolve the question as to the essence of the affection
designated by the name of caries. Therefore we design
to make known only the different modes of expression
relative to it.

“ Caries usually attacks the dentine of the crown of
the teeth, between two folds of enamel. The dentine
becomes of a brownish or blackish color, and dissemi-

* It should be borne in mind that the above views were enun-
ciated more than a third of a century ago. The gentlemen
provably say too much, Compare with Dr. Hayes’s views as
recorded on page xxii.

DENTINE DECAYED, ENAMEL SOFTENED. 145

nates an offensive odor sui generis, which perhaps is
as much owing to the putrefaction of the saliva in the
cavity as to the decomposition of the dentine. The
decay progresses between the folds of enamel, and the
latter substance, notwithstanding its great density,
takes on the blackish tint of the dentine and becomes
sufficiently softened to allow of its being cut by a sharp
instrument. Sometimes even the planes of the enamel
dissolve, and then the cubic mass of the tooth becomes
so much decayed that it resembles a deep cavity, the
parietes of which are formed by the planes of enamel
laid bare by the caries. Sometimes caries attacks the
tooth on one of its four side surfaces; at other times
the root is attacked; but wherever its primitive seat
may be, the blackish veins always extend into the den-
tine, and thus isolate the plies of enamel.

“Carious teeth rarely preserve either their form or
volume. They become hypertrophied at their roots,
but the effect does not manifest itself until the disease
—having undermined all the layers of dentine in its
course—has penetrated the root. When the caries has
penetrated to the socket, the alveolo-dental membrane
becomes irritated by the contact of decayed matter,
increases its secretion, and deposits a thick layer of
osseous matter in the circumference of the root of the
tooth, which concretes irregularly upon the normal
layers. The deposition does not, however, always take
place in the circumference of the root, for in some
cases it is only at isolated places that the secretion of
the alveolo-dental membrane occurs. Then the root
presents a succession of large osseous tubercles, which
bar the tooth in, rendering its extraction very difficult.
When the irrifation has been from the first sufficiently
active to cause suppurative inflammation, the normal

7

oS ee

146 THE PATHOLOGY OF THE TEETH.

secretion is suspended, and pus collects in the alveolar
cavity, around the root, which then ceases to augment
in volume. In the former case, however, the root,
augmented in volume, can no longer be contained in
the cavity, the walls of which are expanded by its
wedge-like action, which accounts for the extreme
pain in the adjacent parts, and the particular altera-
tions in the osseous tissues. ‘The osseous tissue tume-
fies, and suppuration is established in the interior of
the socket; the membrane is partly destroyed, which
leaves the bone bare and exposed to the maceration
of pus and the irritating contact of the morbid matter
that continually penetrates into the socket by the
dental fistula; the bony tissue sphacelates upon the
borders, where its substance is the most compact, and
its spongy tissue, which forms the bottom of the cavity,
soon becomes the seat of an interstitial suppuration—
that is to say, in fact, of veritable caries. The swell-
ing may now extend throughout the entire extent of
the maxillary bone, and thus render mastication im-
possible.

“It may now be seen, an alteration of this nature
being set in action, how the phenomena of the nutri-
tion of bone may be modified in their direction to the
point of producing osteo-sarcoma.

“Caries of the roots of any of the lower grinders may
be complicated with lesions of the jaw, for the lower
jaw is continuous in its entire extent. In the upper
jaw the phenomena are in principle the same, but the
contiguous nasal cavities and sinuses induce complica-
tions the study of which is important. It is also im-
portant to take into consideration the position of the
diseased tooth, in order to appreciate the extent of the
‘legions which a simple caries may produce.

COMPLICATIONS WITH NERVES, SINUSES, ETC. 147

“The two first upper grinder teeth are separated
from the nasal cavities by a thin bone, which is easily
eaten through. When caries attacks their roots, the
inflamma‘ion extends itself to the membrane Lining
these cavities, and a perforation of the osseous partition
may establisa communication between the mouth and
the nose. Under the influence of interstitial suppu-
ration, the osseous membrane is destroyed to an enor-
mous extent. ‘I‘he aliments pass through the dental
fistula into the nose and are expelled by it along with
the product of the morbid secretion of the pituitary
membrane.

“The third grinder is situated near the maxillary
sinuses, from which the root is separated by a thin dia-
phragm. It deserves to be specially noticed on account
of an anatomical peculiarity, which renders caries of
this tooth very much to be dreaded. We refer to the
position of large fusciz (bundles) of the superior maxil-
lary branch of the fifth pair of nerves, which make
their exit upon the face by the submaxillary foramen,
and which are placed immediately over the root of this
tooth. It is easy to imagine the pain that may follow
nervous complications in earies of the roots of the
third grinder.

m The position of the fourth, fifth, and sixth grinder
teeth, immediately below the vast maxillary sinuses,
from which their roots are separated by thin osseous
partitions, gives to caries of these teeth, and to the
complications which it induces, a special character,
which demands that we should speak of it somewhat
in detail. These teeth communicate with the sinuses
as easily as the first and second do with the nose; but
the case is far worse for the horse, there being so little
outlet for the pus.

148 THE PATHOLOGY OF THE TEETH.

“When the disease has penetrated the roots, and
has induced the usual inflammation, the thin parti-
tions that separate them from the sinuses do not resist
very long. Destroyed by the dilatory effort of the
hypertrophied root and the influence of the caries, the
altered matters of the mouth have free access into the
sinuses. Under the influence of their contact, the
membrane of the sinuses irritates, vascularizes, and
thickens by a serous infiltration in the early stage.
Then, the primitive cause of this modification contin-
uing, the membrane hypertrophies somewhat, and in
a short time, owing to its vascular system being richly
developed by inflammation, large vegetations of the
nature of polypi are elevated upon it. ‘These, on ac-
count of the incessant augmentation of their volume,
fill the sinuses and cause a swelling of their walls.

“When the membrane of the sinuses has become
the seat of an abnormal vegetation, an abundant quan-
tity of purulent matter is secreted, the more liquid
part of which drains out through the conduits leading
to the nasal cavities, while the more concrete part
remiins in the sinuses. It then, according as it loses
its serosity, undergoes a transformation, and finally
displays the aspect of cadaveric grease, which*it also
resembles in its repugnant odor. There is a great
analogy between the disease that causes this particular
lesion and that of glanders.

“ Symptomatology—The first symptom that indi-
cates a derangement of the dental apparatus is a diffi-
culty in mastication. The animal, excited by hunger,
seizes the food with avidity. The motions of the lower
jaw, however, are made with a sort of hesitation, and
often only at one side. The imperfectly masticated
hay, which on that account will not pass through the

HUNGRY, BUT UNABLE TO EAT. 149

narrow pharynx, is dropped into the manger in the
form of cuds or flattened pellets. The nose is plunged
into the feed, over which the animal fumbles and nib-
bles, but of which it eats little.

“he insufficiency of nutrition soon produces a
baneful effect on the whole economy. The coat tar-
nishes, becoming dry and staring; the least exertion
makes the animal sweat; it is heedless of the whip;
the mucous membranes become discolored ; the pulse’
weakens, and cold infiltrations sometimes appear in
the extremities. To see an animal thus suddenly
transformed, one is apt to mistake the true cause and
attribute it to the influence of some grave organic dis-
turbance.

“'These symptoms are common to the different dis-
eases and derangements of the dental apparatus, and
are sufficient to lead to a positive diagnosis. The
diagnosis, however, can only be precisely determined
when the mouth shall have been examined, for by this
means we perceive the particular signs of each of the
alterations that opposes the function of mastication.
The mouth may be kept open by a speculum oris, or
even by drawing out the free portion of the tongue,
which should be held’ by the thumb and the third and
fourth fingers, the index being placed between the
inner side of the upper lip and the gum, at the space
between the grinders and the tushes, while the other
hand is left free to aid the inspection by taxis.

“Tf the derangement be the result of an exuberance
of a tooth, vicious inclination or projections of the
tables, fractured teeth, swollen sockets, &., the sight
is ordinarily sufficient to detect it, for the teeth are,
besides, frequently soiled by the greenish remains of
food at the affected part, and often even the cheek is

150 THE PATHOLOGY OF THE TEETH.

filled with an accumulation of malground food. The
mouth should be cleaned with water, in order that the
defect may be more plainly seen; if, however, on ac-
count of its being situated far back in the mouth and
the motions of the base of the tongue from side to side
intercepting the view, its nature cannot be discoy-
ered with the eye, it will be necessary to resort to the
sense of touch. The mouth being held open by the .
speculum oris, or some other firmly-fixed apparatus,
the fingers should be passed rapidly within and without
the arcades, but never on them, because of the danger
of having them crushed: whatever may be the degree
of forced dilatation of the mouth, there can never be
much separation of the jaws in the region of the last
grinders; besides the animal can Jessen it by pressure.
“When the buccal membrane has been excoriated
by the contact of irregularly-worn teeth, the gums in-
flamed, the jawbones contused, and the latter sphace-
late or suppurate, there are some modifications of the
general symptoms. The animal loses its appetite,
becomes dull, ‘crest-fallen,’ and agitated with febrile
disturbance, however little the heart of the inflamma-
tion may be extended. The saliva, which dribbles
from the mouth, is stringy, and, when mixed with
pus, fetid; the mouth is hot and its membrane in-
jected; there is a turgescence of the gum at the point
of inflammation; a tumefaction of the bone, with a
grayish tint at the point where it is denuded and about
to exfoliate, or else fistula abut into the heart of the
suppuration in the spongy tissue of the jaw.
“Particular Symptoms of Caries:—Caries of the
grinder teeth is characterized by peculiar symptoms,
some of which are common to the teeth in general,
while others belong to some grinders in particular.

CARIES DIFFERENT IN DIFFERENT TEETH. 151

To give precision to the diagnosis, the position of the
teeth should be taken into consideration. Besides the
symptoms common to all disorders of the teeth, caries
in general presents as diagnostic signs—

“1. A fetor very remarkable and sui generis of the
mouth, and of the saliva which humefies it.

“2. Dribbling of an abundant and stringy saliva
from the mouth.

“3. Existence on one of the faces of the tooth, and
principally upon its crown, either of a blackish spot or
a large cavity of the same color, according to the ex-
tent of the disease. :

“4, The extreme pain that the animal evinces when
the tooth is struck.

“Tf the disease is of long standing, and especially if
it has arisen from the side of the root, in addition to
the foregoing modifications and complications, other
and more special symptoms manifest themselves. The
bone tumefies and the animal evinces pain when it is
pressed by the fingers; the gums are affected with tur-
gescence, and bleed from the least contact; all the
buccal mucous membrane reflects a red tint, and in
the meantime fever sets in, manifesting itself by all
its ordinary and general symptoms.

“Caries of the first and second upper grinders may,
as already explained, be complicated with lesions of the
nasal cavities. Then the pituitary membrane irritates
and secretes abundant mucosities, but at one side only,
with which the food becomes mixed, giving it a green
tint, but very different from the secretions of glanders.
The case is different, however, in the complications
induced by caries of the last grinders. In fact there

152 THE PATHOLOGY OF THE TEETH.

is such a close resemblance between the symptomatic
expressious of the nose following caries of these teeth
and chronic glanders, that error and confusion are
common. It is therefore highly important to distin-
guish these diseases, so essentially different in their
causes and effects.

“ When the membrane lining the sinuses has become
diseased, followed by the secretion of pus and polypus
growths, a jettage is established at one side of the nose.
lt is white, lumpy, and abundant, and is augmented
in quantity by exercise. The lymphatic ganglions be-
come engorged and hard, but remain indolent, and
generally roll under the finger. The zygomatic tables
of the upper “part of the superior maxillary and nasal
bones swell at the region of the affected sinuses, and
give a dull sound to percussion.*

* Prof. Varnell says: “Iam not aware that any animal suffers
from diseases of the sinuses of the head to the same extent as
the horse. The sinuses differ in size in different breeds, and in
individual horses of the same breed. I need scarcely point out
the necessity of bearing this fact in mind in forming diagnoses
of obscure diseases in this region of the head. In certain cases
it is not only important to ascertain whether the sinuses contain
anything abnormal, but also the nature and extent of the mor-
bific matter. Percussion with the ends of the fingers is one
mode of obtaining this information. Both sides of the head
should be struck, and the sound produced in one part compared
with that in another, and with what it is in health. I would
recommend students to become familiar with these various
sounds. They will be found to differ, according to the magni-
tude of the sinuses, in the same way that a large empty cask,
when struck, will differ in sound from a small one. It will also
be well to educate the ear to the character of the sounds pro-
duced by percussing the sinuses in differently formed heads.
RR pes * The sinuses, strictly speaking, are air cavities,
which communicate freely with each other, and by means of a

— To. a
»
An
'

DELICATE DIAGNOSTIC SIGNS. 153

« At the first appearance of this group of symptoms
one is apt to suspicion the existence of glanders, but a
careful examination will prove it to be unfounded. On
examining the nasa! cavity, the lining membrane will
be seen to be smocth, polished, and uniformly rosy,
with its normal follicular openings, and on unfolding
the superior wing of the nostril, the salient border of
the cartilage presents a neat and polished surface, with-
out any little pimples or morbid tint. Now, we know
that in glanders, even of the sinuses, which is often
unaccompanied by cankers or other ulcerations, it is
in those places certain specific morbid signs may be
recognized, which, although very superficial and with
difficulty seen by the eye, are nevertheless of great
value in the diagnosis. Such, for instance, are the
peculiar aspect of the salient border of the wing of the
nostril, with its vivid red tint, the small superficial
erosions of the lining membrane, entirely hidden under
the fold of the cartilage, and those small granular pro-
jections called tubercles. In the jettage from caries
nothing of this kind exists. There is a marked differ-
ence in the odor too; in caries the odor is exceedingly
fetid, while in glanders it is almost null.

“Tf, after this attentive examination, the surgeon is
still in doubt as to the specific nature of the nasal dis-

small opening, with the nasal passage also. This opening is
situated at the supero-posterior part of the middle meatus, and
is guarded by an imperfect valve, which, when pressed upon
from within, either partially or wholly closes it. It may also
be closed by the mucous membrane being thickened by disease.
Internally the sinuses are partially divided into compartments
by thin osseous plates, and are lined by aslightly vascular mem-
brane, whieh is continuous with that of the nasal passage, but
is not so thick nor so vascular.”

154 THE PATHOLOGY OF THE TEETH.

charge, it will disappear and give place to a true diag-
nosis when he has examined the mouth and has had
time to weigh and compare all the facts in connection
with the case.

“Jt is more especially relative to diseases of the teeth
that is recognized the truth of tne old maxim in sur-
gery, Sublatd causd, tollitur effectus.” (‘The cause be-
ing removed, the effect ceases. )

For putting irregular teeth in order, the surgeons
recommend the use of a course, six-inch file, with a
handle from twenty to twenty-four inches long. How-
ever, they say that in their day it was customary among
the “vulgar” to make the horse chew a rasp! The
process, which they describe, referring among other
things to the difficulty of getting the rasp precisely
opposite the projections, is too slow, as they admit, to
be practicable; besides it is about as difficult to com-
pel a horse to chew as to compel him to drink.

For the removal of supernumerary grinder teeth or
the shortening of natural ones that have grown beyond
the level of the other teeth, they recommend the use
of a chisel and a hammer; two or three well-directed
blows with the latter are usually sufficient to cut the
largest tooth in two. The surgeon requires an assist-
ant or “striker.” In the case of the first grinder, the
blows should be light, otherwise the tooth would be
loosened in its socket. In the case of the last grinder,
“it is necessary for the operator to be perfectly master
of the chisel at the moment of its being strack, for, in
escaping, it might strike against the velum palati (soft
palate) and cut it through.”

In performing these operations they prefer that the
horse should be in a standing position, as when in a

DRENCHED WITH TOOTH-FRAGMENTS. 155

lying position there is danger of his swallowing the
fragments of the teeth. If it is necessary, however, to
cast the horse, they recommend that the head rest on
the occiput, the operators being as expeditious as pos-
sible, to prevent the animal from swallowing the frag-
ments. As the nose points up,-the surgeon would
have to be expeditious indeed in order to prevent the
horse from being drenched, as it were, with tooth-
fragments.

The surgeons next describe an interesting case of
dental surgery, in the performance of which the bone-
forceps were used to remove the tushes. ‘They say:

“Tt sometimes happens that the fleshy and bony
structures of the mouth are not weil proportioned, and
when the animal is put to work evil consequences re-
sult, especially if the tongue is too large for the space
between the branches of the jaws. A remarkable case
of this kind lately came under our observation in a
horse owned by the Earl of Clonmel. The animal, a
remarkably fine one, was a very hard ‘ puller,’ in conse-
quence of the bit not coming in sufficient contact with
the sensitive bars. The space between the tushes was
too narrow for the tongue, which, after the animal had
been ridden with restraint by a horse-breaker, was cut
nearly through at each side. The consequence was the
tongue became swollen to an enormous extent, and
as the tushes increased the irritation, their removal
became necessary. They were ent off to a level with
the gums with the bone-forceps, the tongue was scari-
fied and bathed with a cold lotion, and the animal was
fit for work at the end of a week.

“ Perhapssat first it may seem better practice in such
cases to extract the tushes entirely. But when the

a

156 THE PATHOLOGY OF THE TEETH.

length and obliquity of their roots and the fact of their
being situated in the weakest part of the jaw are con-
sidered, it is plain that such a procedure would in all
probability be followed by the most serious results,
such as fracture of the jaw, osteo-sarcoma, &e., the
former having happened under our own observation.”

The surgeons recommend (as any inteliigent person
would) the removal of supernumerary or abnormal in-
cisor teeth. When the tooth is without the normal
range it interferes with the prehensile function of the
lips;. when within, it interferes with the tongue. The
former, they say, may either be cut off with the bone-
forceps or extracted. In the latter case, however, they
prefer to cut them off, but admit that some teeth re-
quire extraction, for which the use of the crank-forceps
is recommended.

The Treatment of Caries is the next subject consid-
ered. “The only remedy for caries,” the surgeons say,
“in the great majority of cases, is the extraction of the
tooth. If we were called on to treat the disease at its
beginning, cauterizing the black spot would check its
progress; but when the dental bulb has been attacked,
the extraction of the tooth is the only remedy.”

The instrument recommended for extracting teeth
is the forceps, and under ordinary circumstances, the
surgeons say, fracture of the jaws ought not to occur.
They mention as useful instruments the key invented
by M. Garengeot, the mouth-screw by M. Plasse, and
the lever-forceps by Prof. Simonds, but say:

“Tnstances occur in which the carious tooth cannot
be seized by any of these instruments. For example,
when the last upper grinder is diseased, it is sometimes

«. eS. © 2 eee
i —_
.?

THE POWER OF THE TONGUE. 157

impossible to dilate the mouth sufficiently to slide the
instrument between it and the corresponding lower
tooth. Besides, the tongue, however firmly it may be
held outside the mouth, has still the power to displace
the instrument by the energy of the undulatory moye-
ments at its base. Again, the back grinders, having
ordinarily shorter bodies than the others, afford less
hold for the instrument. In some cases they afford no
hold at all, as their bodies are worn almost to a level
’ with the gums.

“Lastly, in some cases the exostosis of the root of
the tooth is so great that it is, as it were, wedged in
the socket, and resists all efforts to extract it. What
is to be done? The disease may lead to grave local
complications and dangerous. general disorders. In
such a case we would recommend trephining the dis-
eased sinus and punching the tooth into the mouth.
‘This operation being very unusual, and the observance
of some rules requisite for practicing it, we will con-
sider it somewhat in detail.

“Tf, as sometimes happens, the swelling over the
sinus is indistinct, it would be well to be guided by a
prepared head, in order to apply the trephine in the
exact place, which is above the diseased root. A large
V or crucial incision should be made, and the trephine
manipulated till the sinus is laid open. The opening
should be extensive rather than confined; it is more
convenient to apply upon the parietes of the sinuses
three crowns of the trephine, tangent reciprocally at
their circumferences; then, by the aid of a sharp in-
strument and a small hammer, the angles may be re-
moved. |

“As soon as the mucous membrane of the cavity has
been laid bare, the change it has undergone may be

158 THE PATHOLOGY OF THE TEETH.

seen, and also the vegetations springing from it. -At
the bettom of the sinus, toward the alveolar border of
the jaw, among the vegetations, is a hard, granulated,
dry surface, resistant to the touch, of a grayish tint,
and analogous to sphacelated bone. ‘Lhis is the sum-
mit of the root of the tooth.

“The surgeon then arms himself with an iron punch,
rounded at the point, which he applies to the root in
the sinus, and having further separated the jaws by a
few turns of the speculum oris, commands an assistant
to strike sher/, hard blows, the surgeon looking at the
tooth to see the effect of each blow. Usually the tooth
soon gives way, and falls into the mouth generally in
two fragments, according to the direction of the caries.
Sometimes, however, from the length of the tooth, it
cannot be punched entirely into the mouth, being
stopped by the opposite lower tooth; but it may be
wrenched out with a pair of long pincers, the handles
of which should be separated to increase the power of
the operator. When the operation is terminated, the
vegetations of the mucous membrane, as far as they
can be reached, must be excised. ‘To stop the hem-
orrhage, and to modify the state of the membrane,
pledgets of tow, moistened with a diluted solution of
nitric acid, or some other caustic, should be applied.

“Tt is really extraordinary with what rapidity the
structural breaches resulting from this operation are
restored by the reparatory efforts of the organic econ-
omy. The first time we performed the operation we
doubted the animal’s recovery. The sinuses, laid open .
by a breach nearly two inches and a half in diameter,
communicated with the mouth by an enormous open-
ing, the root of the tooth having acquired nearly three
times its normal volume. The lining membrane of

7

TREATMENT AFTER TREPHINING. 159

the maxillary sinuses, and the frontal also, had suffered
the transformation already described to its greatest
degree. And, finally, at required efforts ulmost beyond
belief to loosen the tooth and force it from its socket.
Still the animal made a good recovery.

“The treatment fullowing the operation should be
as follows: Assiduous attention to cleanliness is nec-
essary from the first.. On the first day the animal
should be deprived of all solid or fibrous food; in fact,
a little thin gruel is all it requires, and the mouth
should be gargled with an acidulated fluid even after
its use. The fluid may be applied with an ordinary
syringe. Bleeding is often required, the quantity of
blood to be abstracted depending on the energy of the
reaction following the operation.

“On the day after the operation the dressing should
be raised. The interior of the sinus, cauterized with
nitric acid, reflects a blackish tint. The odor is repug-
nant, and there are generally some remains of putrid
alimentary matters, mixed with clots of blood, in the
sinus. Detergents, such as Lebarraque’s chlorinated
solution of soda, mixed with a gentian wine, should be
injected into the sinus and the mouth cleaned with
acid gargles; a firm pledget of chlorinated tow should
be introduced into the socket, to prevent anything
passing from the mouth to the sinus. The regimen
should consist of gruel only, the gargles to be used
often during the day.

“On the second day the borders of the sinus will be
a little swollen. Reparatory work has begun in the
cauterized membrane; the eschars detach themselves,
exposing a rosy surface of favorable aspect to the view.
The odor is less repugnant. Continue the aromatic
detergent injections, the same food, with the addition

160 THE PATHOLOGY OF THE TEETH.

of a little bran, and gargle often. As sappuration be-
gins to establish itself, the dressings should be renewed
two or three times during the twenty-four hours.

“Tt is not our intention to indicate the progress of
the wound and the attention it demands from day to
day. he tumefied bones and other structures in the
region of the wound proportionally lessen, and the
membrane of the sinus takes on a uniformly rosy tint
and the glistening, humid aspect proper to a mucous
membrane. The nasal flux finally ceases, the matter
that may be secreted finding an outlet through the
alveolus into the mouth. The opening made by the
trephine contracts itself by degrees, but in extreme
cases, like the one we have described, it is never suffi-
cient to entirely repair the structures cut away. It
may be hidden, however, by a leather or metallic plate,
attached to the check of the bridle.”

The surgeons claim that the resort to this severe
mode of extracting teeth is justified by the success of
the operation and its concomitant results, namely, the
advantage of injecting the sinuses and preventing un-
healthy secretions by them, and the stopping of the
discharge from the nose, which had aroused suspicion
of glanders. They further say—and a better argument
in favor of veterinary dentistry could not well be ad-
vanced—that they believe glanders is often caused by
the neglect of diseased teeth, and “that the modus
operandi of its production in such cases may be ex-
plained on the ground of the absorption of pus by the
constitution.”

Of trephining the sinuses they further say:

“We have treated many cases of caries successfully
by simply trephining the frontal and maxillary sinuses

Mate ee

CARIES OF THE SOCKET BONES. 161

and injecting detergents; but in a far greater number
the treatment has been unsuccessful.* Yet we believe
that if, in addition to trephining, the teeth had been
extracted, and a communication established between
the sinus and the moutii, the results would have been
more favorable.

« Monsieur Delafond, in his memoir on the evulsion
of the teeth, published in 1831, says the operation of
trephining is only practicable in the case of the three
first grinders, it being necessary in the case of the three
last to make an incision through the zygomatico-maxil-
Jaris muscle and the nervous plexus which is formed
on it. We, on the contrary, claim that the fifth pair
of nerves will be injured in operating on the three first
teeth, but that there will be little injury to the muscle
in the ease of the three last.”

The memoir concludes as follows:

“Onries Attacking the Maxillary Bone after the Ez-
traction of the Feeth—When caries of a tooth has in-
duced consecutively interstitial suppuration of the
spongy tissue of the socket, it is possible that, even
after the extraction of the tooth, the disease may at-
tack the bone. Then, more than ever, may we dread
the tumefaction of the tissues and sarcomatous altera-
tions, which are ordinarily the result of persistent sup-
puration in the areole of the spongy substance of the
bones. To prevent these dangerous consequences, the
socket should be cauterized with the actual cautery,

*“Sinuses that may have formed by the matter from ab-
scesses in the alveolar processes eating its way through the wall
of the alveolus, and which may open either on some part of the
face or within the mouth. are seldom treated with the success
one could desire."—Pra;. Goi ge Varnell.

162 THE PATHOLOGY OF THE TEETH.

and, if it is practicable, a counter opening by trephin-
ing should be made. In some cases in our practice
this mode of treatment produced the most satisfactory
results. If, however, on account of the circumstances
of the case, the actual cautery cannot be used, a strong
solution of argenti nitras, applied with pledgets of tow
or lint, may be substituted.

“ Complications of Operations on the Mouth.—One of
the most ordinary and serious complications of opera-
tions on the mouth is the excoriation of the ‘bars’ by
the friction of the speculum oris. The denuded bone
often exfoliates, rendering the horse uniit for work for
a month or more. The evil may be avoided by envel-
oping the transverse bars cf the speculum with tow or
some other elastic material, and by being expeditious
in operating. The hemorrhage, which is never abun-
dant enough to be serious, may be checked by pledgets
of tow, wet with a solution of either nitric or sulphuric
acid.

“ Regumen.—The regimen in extreme cases of caries
has already been indicated in the account of the case
of trephining for caries and exostosis of the root of a
grinder. In addition to well-boiled gruel, mixed or
unmixed with bran, carrots and similar food will be
found beneficial.” *

* As horses with defective, diseased, or worn-out teeth require
soft or ground food, a few extracts from the article on “ Food”
in Prof. Youatt’s work entitled “The Horse” (p. 122) and other
sources will not be out of place here: ‘“ Oatmeal gruel consti-
tutes one of the most important articles of diet for the sick
horse. Few grooms make good grnel. It is either not boiled
long enough. or a sufficient quantity is not used. The propor-
tions should be a pound of meal toa gallon of water. It should
be constantly stirred till it boils, and for five minutes afterward.
Carrots, according to Stewart’s ‘Stable Heonomy,’ are a good

PROF. VARNELL’S VIEWS. 163

Prof. George Varnell, of the Royal Veterinary Col-
lege of London, the author of a series of articles “On

substitute for grass, and in sick or idle horses render corn un-
necessary. ‘They improve the state of the skin. At first they
are slightly diuretic and laxative, but the effect lessens with use.
Half a bushel is a large daily allowance. Swedish turnips and
raw potatoes are useful foods. Raw potatoes, sliced and mixed
with chaif, may be given to advantage, but it is better to boil or
steam them, as purging rarely ensues. For horses recovering
from sickness, barley in the form of mali is serviceable as tempt-
ing the appetite and recruiting the strength. It is best given
in mashes, water somewhat below the boiling heat being poured
upon it, and the vessel kept covered for half an hour, Rye is
used in Germany, but generally cooked as bread, which is made
from the whole flour and bran. It is not unusual in traveling
through some parts of Germany and Holland to see the postil-
ions help themselves and their horses from the same loaf. In
some northern countries peameal is frequently used, not only as
food, but as a remedy for diabetes. Linseed, raw, ground, or
boiled, is sometimes given to sick horses. Half a pint may be
mixed with the feed every night. It is supposed to be useful in
cases of catarrh. It is very useful for a cough, but it is too
nutritious for a fever. For a cough it should be boiled and
given in a bran mash, to which two or three ounces of coarse
sugar may be added. Tares, cut after the pods are formed, but
some time before the seeds are ripe, lucern, and sainfoin are
useful foods. Of the former the variety known as Vicia sativa
is the best.”

On page 511 Prof. Youatt says “some greedy horses habitu-
ally swallow their food without properly grinding it.” As a
remedy he recommends that chaff be mixed with the corn, cats,
or beans, which, being too hard and sharp to be swallowed with-
out chewing, compels the horse to masticate his food. He says:
“ Chaff may be composed of ejual quantities of clover or meadow
hay and wheaten, oaten, or barley straw, cut in pieces of a quar-
ter or a half an inch in length, and mixed well together. The
allowance of corn, oats, or beans is added afterward, and mixed
with the chaff. “Many farmers very properly bruise the oats and
beans. The whole oat is apt to slip out of the chaff and be lost,

1%

164 THE PATHOLOGY OF THE TEETH.

Some of the Diseases Affecting the Facial Region of
the Horse’s Head” (“ Veterinarian,’ 1866-67), and
other productions, has made the disorders of horses’
teeth a study, and has aided somewhat in clearing the
“mystery” that Surgeon Gowing believes will “to a
certain extent always remain,” for he has succeeded in
casting some light on the etiology of a tooth’s greatest
enemy—caries. His suggestion as to plugging teeth
with gutta-percha is novel, and in some cases might
be practicable. However, would not cement, which
gives such perfect satisfaction in human dentistry, be
preferable? It is not expensive, and can be as readily
introduced into a cavity as gutta-percha; besides, as
the cavity must first be thoroughly cleaned (no matter
which is used), its use in the end might saye time and
the tooth be much longer preserved. A horse’s tooth
that can be got at conveniently, ought to be filled as
easily and, in decay of its neck, perhaps a3 successfully
as a human tooth. Prof. Varnell’s views are in sub-
stance as follows (“ Veterinarian,” 1867):

“Caries of the roots of the grinder teeth is rare and
generally very difficult to account for. I think that,
in the majority of cases, it depends upon external vio-

For old horses, and for those with defective teeth, chaff is pecu-
liarly useful, and for both classes the grain should be broken as
well as the fodder. The proportions are eight pounds of oats
and two of beans to twenty of chaff.”

Concerning swallowing without grinding Prof. Youatt further
says: “In cases of this kind the teeth should be examined.
Some of them may be unduly lengthened, particularly the first
of the grinders, or their ragged edges may wound the cheek. In
the former case the horse cannot properly masticate his food ;
in the latter he will not, for horses, as too often occurs in sore
throat, would rather starve than put themselves to much pain.”

—.? ire.

THE ALVEOLO-DENTAL PERIOSTEUM. 165

lence, although we are not always able to trace it to
such acause. Inflammation of the alveolo-dental peri-
osteum, especially where it surrounds the root or roots
of a tooth, would tend to this result. Other causes
may produce the same effect. Indeed, whenever or
however effected, when the nutrition of any part of a
tooth ceases, decay is likely to follow. When caries
begins from within, it is due to cessation of nutrition,
arising perhaps from disease of only a part of the cen-
tral pulp of the tooth. If from withont, it arises from
the periodontal membrane where it meets the gum.

“Oaries of the cervix (neck) of the tooth is much
more common than it is in the root; still it does not
oceur in more than one horse in five hundred. The
question will naturally be asked, ‘To what does this
tendency to decay belong? Under such circumstances
are we not forced to the conclusion that it must de-
pend either upon a defective structure of the tooth, or
that the dentine, enamel, and cement are dispropor-
tionately developed, or that one of them is defective in
its parts? Another and perhaps the most frequent
predisposing cause of caries of the neck of the grinder
teeth is that food becomes impacted between them.
Its decomposition may not only affect the teeth, but
the alveolar processes also.”

The professor believes that caries of the crown of a
tooth is generally caused by the horse biting on a stone
or piece of metal during mastication. If the stone is
lodged in the cavity of the infundibulum, the pulp of
the tooth may be injured, for, to use the professor's
words, “ the thickness of the tooth between the upper
part of the ptilp-cavity and the bottom of the deepest
infundibula is not very great.”

166 THE PATHOLOGY OF THE TEETH.

Of the treatment of caries of the necks and crowns
of grinder teeth, the professor says:

«“ As I am not aware of any treatment by which the
decaying process can be stopped, I would as an experi-
ment in suitable cases—that is, in those in which the
diseased part may be got at—plug the tooth with gitta-
percha, having first thoroughly cleaned the cavity. If
the plug can be retained in its place, some benefit may
be derived from its use. Believing, however, that the
decomposition of food impacted between the grinder
teeth is one of the exciting causes of their decay, I
would advise that it be now and then removed. It
would not only prevent decay, but in cases where decay
had already begun, would to some extent check its pro-
gress. Indeed, I think the health of the horse would
in many cases be improved by the adoption of such a
plan.”

While the professor recommends gutta-percha plugs
for the crowns of slightly decayed grinders, he says
that, compared with those of the necks, they are “less
likely to be of even a slight benefit, inasmuch as the
plug would be removed by attrition.” Where the in-
terior of the grinder is destroyed by disease, and the
usual longitudinal fracture has occurred, he extracts
the tooth with the forceps. While, as a rule, the tooth
fractures longitudinaily, the corners, he says, are some-
times broken off.

In commenting on the diseases of the alveolar pro-
cesses, Prof. Varnell says:

“The causes which give rise to this condition of the
maxillary bones are not easy to define. That a horse
so affected is from certain peculiarities predisposed to

» On, DO rn
il os :
4

j

DISEASE OF ALVEOLAR PROCESSES. 167

it, there can be no doubt. For example, the teeth be-

ing placed at a distance from each other, thereby allow-
ing the food to lodge between them, must be looked
upon as a predisposing cause. A strumous diathesis,
which I believe to be more common in the horse than
is usually supposed, must also be regarded as a predis-
posing cause. The particles of food which become
impacted in these unusually wide interdental spaces,
after a time decompose and give rise to fetid com-
pounds, which act prejudiciaily on the parts they are in
contact with. The membrane which covers.the gums,
and also that which hnes the alveoli and is reflected
on the roots of the teeth, becomes inflamed. The
inflammation will extend to the bone, the blood-vessels
of which will become enlarged, as will also the Haver-
sian canals in which they ramify. The osseous laminz
surrounding these canals will be partially absorbed,
and to some extent separated from each other, and the

enlarged spaces thus produced will be filled with in-

flammatory exudation. Hence the soft, spongy state
of the gums and their tendency to bleed from slight
causes; hence also the looseness of the teeth in the
alveoh.”

Of the deformity called Parrot-Mouth, and irregular-
ities of the incisor teeth, Prof. Varnell says:

“This deformity consists in the upper incisor teeth
projecting in front of and overhanging the lower ones
to the extent in some instances of an ineh and a half.
The deformity resembles the upper bill of the parrot,
which projects over the lower; henee the name. The
lower incisors, from not being worn off by attrition,
may become so long that the roof of the mouth is seri-
ously injured. The deformity is generally associated

168 THE PATHOLOGY OF THE TEETH.

with an irregular position of the upper grinders rela-
tively with the lower.

“Sometimes the horse, when at pasture, is unable to
take a sufficient quantity of food to keep himself in
condition, and consequently he is considered legally
unsound. But if fed from the manger he experiences
little trouble in collecting his food; nor will his ability
to masticate it be interfered with, except perhaps in
old age.

“ Treatment.—The treatment can only be palliative.
If the roof of the mouth should become diseased and
mastication impaired, the only remedy is to reduce the
length of the lower incisors. The instrument generally
used is a file or a rasp, but the process is so tedious and
slow that it is seldom that much good is done. Ifthe
sliding-chisel could be brought to bear on them, their
length could be readily reduced. ‘Talking on the sub-
ject with my friend, Surgeon Gowing, he suggested a
modification of this instrument which, I think, would
answer very well.

“Trregularities of the incisor teeth, both with refer-
ence to their position and number, are even more com-
mon than in the grinders, but they seldom cause actual
disease.”

Prof. William Williams, like Prof. Varnell, has per-
formed his part in elucidating the subject of caries of
the teeth, and he has also ilustrated the transmission
of vitality to them from the outside—through the me-
dium of the cement—after it has ceased to flow through
the pulp on the inside, the pulp having become con-
verted into dentine. It appears that anything that
disturbs the equilibrium of this flow of vitality, which
is the secret of the growth of the tecth throughout

—

CEMENT FILLING THE PULP’S OFFICE. 169

life, may cause caries. Prof. Williams says (“ Princi-
ples and Practice of Veterinary Surgery,” p. 470):

“Caries, dental gangrene, or decay, is almost exclu-
sively confined to the grinder teeth—although I have
seen the incisors in that condition—and may begin
primarily in the root, neck, or crown of the tooth.

“ Caries of the root arises from inflammation of the
pulp, and may be caused by a constitutional predispo-
sition or external injury. Inflammation of the pulp,
however, does not always cause caries. I have several
cases on record where the roots were enlarged from
periodontal deposit, with abscesses surrounding the
roots, without caries. Caries beginning at the roots
may be due to the obliteration of the pulp-cavity at
an age when the vitality of the tooth depends upon
the integrity of the pulp. I need scarcely remind the
professional reader that the integrity of the teeth de-
pends upon a due supply, both as to quantity and
quality, of nutritive materials.

“On the roots of a recently cut tooth but little
cement is met with compared with that which exists
in old teeth.. As age advances the cement increases,
and the tooth grows from the outside. In man it is
generally agreed that after a given time the dentine
ceases to be produced, and that the pulp is converted
into osteodentine. In the horse the pulp-cavity be-
comes obliterated gradually by the pulp continuing to
form dentine, the pulp simply giving way to its own
product, which ultimately occupies its place and fills
its cavity. In proportion as the pulp diminishes the
supply of nutriment is lessened, until at length it 1s
entirely cut off from the interior; to provide for the
vitality of the tooth the cement increases in quantity

8

170 THE PATHOLOGY OF THE TEETH.

on the root, and at the expense of the perfectly formed
dentine lying in immediate coutact with its inner sur-
face. That is to say, this layer of dentine is converted
into cement by the dentinal lacune undergoing dila-
tution and becoming identical with the hollow spaces
or cells of the cement. The tooth now draws its nour-
ishment from the blood-vessels of the socket, and thus
continues, long after the obliteration of its pulp-cavity,
to perform its part in the living organism.

“This is the natural condition of old teeth. But
when the puip-cavity is obliterated at an early age, by
a too rapid formation of dentine, and consequent ob-
literation of the pulp when the cement is not yet sufli-
ciently developed to supply nourishment to the whole
tooth, caries must be the result. Many cases of caries
that have come under my observation have resulted
from this cause, and very often the disease is confined
to that part of the cement that dips with the enamel
into the interior of the tooth, splitting it into several
longitudinal fragments.

“Caries of the neck of the tooth is seen in those
horses whose teeth are wide apart, and is caused by
the food remaining in the interspaces, and by decom-
position exciting inflammation in the periodontal
membrane. Caries of the neck is very commonly met
with in the teeth of dogs, sometimes causing abscesses
in the cheek.

“Caries beginning at the crown is due to a portion
of the dentine losing vitality and the power of resist-
ing the chemical action of the fluids of the mouth. A
portion of the enamel of the crown may be fractured
by biting a stone or piece of metal contained in the
food. Mere fracture of the enamel, however, is insuffi-
cient of itself to lead to caries of the teeth in the lower

—

SIFTING THE FEED. 171

animals, for it is a substance that is gradually worn
off by mastication; but the violence which has caused
fracture of the enamel, mav at the same time have
caused such an amount of injury to the dentine that
it dies, and progressively becomes decomposed. In
man it seems there should be death of the dentine and
acidity of the oral fluids before caries can take place,
test-paper applied to a carious tooth invariably show-
ing the presence of free acid, and a very smaft perfora-
tion in the enamel may coexist with a considerable
amount of disease in the dentine.”

Surgeon T. W. Gowing, of London, a well-known
inventor of dental instruments (veterinary), in an
* Hssay on the Diseases of the Teeth of the Horse,”
which was printed in “The Veterinarian” for 1851
(p. 632), in substance says:

“T am aware that the cause of disease of the teeth
must to a certain extent always remain a mystery; yet
from observation and reflection we may be able to de-
duce conclusions which practice will confirm.

“Tet us consider the two classes of horses that we
are principally called upon to attend, namely, the cart
or draft-horse, and the hack or earriage-horse. So far
as my observations have led me, the latter class are
less liable to diseases of the teeth than those of a
coarser breed. Now, may not this be caused by the
better care they receive in the stable? The good and
efficient groom regularly sifts the provender previous
to feeding his horses, and thus rids it of stones, glass,
&e. The cart-horse and the machine-horse of our
London omnibus proprietors, not receiving this atten-
tion, are more subject to diseases of the teeth. Be-
sides, it is a common practice with carters to sprinkle

172 THE PATHOLOGY OF THE TEETH.

the provender with sulphuric acid, and we well know
how acids affect the teeth. If such practices be al-
lowed, diseases of the teeth may be readily accounted
for.

“The teeth being lowly organized, soon lose their
power of self-preservation. ‘They are affected by the
general health of the animal. Should the function of
the stomach or alimentary track be deranged, the teeth
—from the general health of the animal being inter-
fered with, and from the local functional derangement —
—of all parts of the body, are the first to suffer or de-
cay. Absorption of the gums, which may be caused
by the decayed food that lodges between the grinders,
is often followed by decay of the cement, which, being
the most exterior as well as the most highly organized
of the three substances composing the teeth, is the
first to yield.”

After describing the usual symptoms of diseased
teeth, Surgeon Gowing asks:

“ Who that has observed these symptoms, can hesi-
tate for a moment to acknowledge that the animal is
suffering pain, which, if we were to say arose from
toothache, would not be believed by our employers?”

Prof. W. Youatt says in substance (“The Horse,”
p. 230):

“Of the diseases of the teeth we know little. Cari-
ous teeth are occasionally seen. They not only render
mastication difficult, but they sometimes impart a fetid
odor to the food, and the horse acquires a distaste for
aliment altogether. Carious teeth should be extracted
as soon as their real state is known, for the disease is
often communicated to the contiguous teeth and to

oo ih
— te
]
‘
” -

FUNGUS HA MATODES. iva

the jaw also. Dreadful cases of ‘fungus hematodes’
have arisen from the irritation of caries.

“Every horse that gets thin or out of condition,
without fever or other apparent cause, should have his
teeth and mouth examined, especially if, without any
indication of sore throat, he ‘quids’ his food; or if he
holds his head to one side while he eats, in order to
get the food between the outer edges of his teeth. The
cause is irregular teeth. Such a horse is materially
lessened in value and is to ail intents and purposes
unsound, for although the teeth may be carefully sawn
down, they will project again at no great length of
time. <A horse cannot be in full possession of his nat-
ural powers without perfect nutrition, and nutrition
is rendered imperfect by any defect in mastication.”

Prof. R. Owen, in his work entitled “A History of
British Fossil Mammals and Birds” (pp. 388-9), gives
an account of a diseased fossil horse’s tooth which he
found at Cromer. He says he is “induced to cite one
of the curious examples of disease in an extinct animal
from the rarity of its occurrence in the tissue which is
the subject of it.” The facts of this rare case are as
follows:

“One of the Cromer fossil teeth, from the lower jaw,
with a grinding surface measuring one inch five lines
in long (antero-posterior) diameter, and eight lines in
short (transverse) diameter, presented a swelling of
one lobe, near the base of the implanted part of the
tooth. To ascertain the nature and cause of this en-
largement, I divided it transversely, and exposed a
nearly spherical cavity, large enough to contain a
pistol-ball, with a smooth inner surface. The parietes
of this cavity, composed of dentine and enamel of the

174 THE PATHOLOGY OF THE TEETH.

natural structure, were from one to two lines and a
half thick, and were entire and imperforate. The
water percolating the stratum in which this teoth
had lain, had found access to the cavity through the
porous texture of its walls, and had deposited on its
interior a thin ferruginous crust; but the cavity had
evidently been the result of some inflammatory and
ulcerative process in the original formative pulp of
the tooth, very analogous to the disease called ‘spina
ventosa’ in bone.”

CHAPTER IX.
THE DENTISTRY OF THE TEETH.

Reports of Cases Treated by Various Surgeons.—Gnuita-Percha
as a Filling for Trephined Sinuses.—Teeth Pressing against
the Palate. —Passing a Probe through a Decayed Tooth,—
Death of a Horse from Swallowing a Diseased Tooth.

HorsEMEN, farmers, and other practical men will
find much useful information in the present chapter,
for it is based on the experiences of Veterinary Sur-
geons, whose reports appear in the various volumes of
“The Veterinarian” (printed monthly in London),
and to which I am so much indebted for other useful
information. It is probably not too much to say that
the more generally the chapter is read the fewer horses
will be killed in the future for having decayed teeth,
accompanied with a discharge from the nostril.

In “The Veterinarian” for 1856 (p. 437) Surgeon J.
Horsburgh reports the following interesting case, en-
titled “Chronic Nasal Gleet produced by a Diseased
Tooth :”

“About twelve months ago I was consulted about
the case of a mare with a discharge from the near nos-
tril. She had been under treatment for eighteen
months, and the superior maxillary sinus had been
opened with the trephine. The discharge, however,
continued to flow, both from the nostril and the

176 THE DENTISTRY OF THE TEETH.

wound, notwithstanding the trephining had been per-
formed a year before I saw the animal.

“The defluction had an offensive smell, and the sub-
maxillary gland was enlarged, causing suspicion of
glanders. The opening had been made a little too
high, so that the central instead of the superior part
of the sinus was perforated. I found that the whole
mischief was caused by a diseased tooth. With the
assistance of a smith I removed the tooth, which was
split up its middle and considerably decayed. It was
more than two inches long, and was bent forward to-
ward the cheek. The odor was most offensive. I then
opened the frontal and maxillary sinuses, both of
which were filled with fetid pus. The wounds were
first treated with a weak solution of chloride of lime,
and subsequently with an ordinary astringent lotion.
In addition to the local treatment, I administered the
diniodide of copper.

“ After a considerable time the wounds were allowed
to heal, and the mare appeared much better. But very
shortly the discharge began to flow again worse than
ever, and the smell was almost intolerable. Deter-
mined, if possible, to make a cure of the case, I cut
into the sinus again with the skull-saw, taking out a
triangular piece of bone about two inches long by one
inch and a half broad. At the upper part of the
cavity I found some masticated food in a state of de-
composition. It had passed through the alveolus into
the sinus. Fractured bones were removed, and the
opening being extended through into the nostril, a
small instrument could be passed down it into the
mouth. A weak nitric acid lotion was used to induce
fresh inflammatory action, and, if possible, to fill up,
by an effusion of lymph, the passage through which

CURED INSTEAD OF KILLED. 17%

the food was pressed upward from the mouth into the
cavity. The external wound was dressed with an

- ordinary healing lotion, and tow was put into it daily,
and pressed downward to the mouth. A little blister
liniment was also occasionally applied.

« Before operating, the frontal sinus on the affected
side was considerably more bulging than the other. It
is now reduced, and the wound has healed. The dis-
charge from the nose has stopped, and there is no
smell. Thus, after about two years and a half of
treatment, this mare, now only five years old, is able
to resume her work, and has every appearance of being
likely to remain well.

“Had I not been able to effect a cure by the closing
of the passage into the mouth, I would have tried
filling it with gutta-percha. Ifa discharge were to
take place again in this case, it would no doubt depend
on the existence of a small aperture, and, under such
circumstances, I should not hesitate to again cut into
the sinus and endeavor to close the opening in the
bone with gutta-percha, or some similar substance.”

Surgeon H. Surmon, in an article “ On the Extrac-
tion of Projecting Teeth,” tells how he saved a horse
that had been ordered killed by its owner (“ Veterina-

. fian,” vol. ii, p. 25):

“Last year a neighbor of mine had a horse which
had been losing flesh for some time, and his appetite
was gradually diminishing. When I first examined
the horse I saw no appearance of disease that could
affect his appetite, and looking at his mouth I per-
ceived no laceration of the cheeks or other injury.
The horsergrew worse, became almost a skeleton, and
its owner ordered that it be killed. Being informed

178 THE DENTISTRY OF THE TEETH.

of the fact, I expressed a wish to examine his mouth
once more. I accordingly put'a balling-iron into his
mouth and introduced my hand, and at the extremity
of the grinders I found two teeth, one on each side of
the lower jaw, which had grown long enough to press
into the roof of the mouth, and thus prevented the
animal from eating. I endeavored to extract these
teeth with an instrument similar to that used for the
human teeth, but without effect, as it could not be
got on them. I then contrived an instrnment which
was very simple. When it was passed up the mouth,
the tooth became fixed between the divided end of the
iron; the handle being then turned, the tooth was
extracted with the greatest ease. From that moment
the horse began to feed, and rapidly improved in con-
dition. In a short time he went to work, and has done
well.”

Surgeon C. May, of Malden, Eng., thus tells how he
cured “A Case of Disease of the Jaw” (“ Veterinarian,”
1834, p. 93):

“T was requested by Mr. Ram, of Purleigh, to look
at a horse which he told me had a ‘cancer’ im his jaw.
I found my patient, a fine young chaise-horse, looking
very poor, and having a constant discharge from the
region of the root of the second lower grinder. There
was considerable enlargement of the bone, which led
me to-suspect disease of the tooth, and which, on ex-
amination, proved to be true. On introducing a probe
into the orifice, I found that it went through the tooth
into the mouth. I was informed that this supposed
cancer had been under the treatment of a farrier, and
that the poor beast had been subjected to many pain-
ful caustic applications. As I was satisfied that ne

~

THREE UPPER GRINDERS EXTRACTED. 179

good could be done to the jaw as long as the tooth re-
mained in it, I decided to extract it. I had an instru-
ment made similar to the key used in human dentistry,
with a handle like that of an auger. Having cast my
patient and lanced the gum, I fixed the instrument on
the tooth and succeeded in extracting it, although it
required nearly all my strength. ‘There was but
trifling hemorrhage, and the ‘cancer’ soon got well.
I think our patients are more frequently the subjects
of toothache than we suppose. Perhaps ‘quidding’ in
many of them might be traced to a carious tooth.”

In a report of ten cases of diseased teeth that were
treated at the Edinburgh Veterinary College during
the year 1845, the details of one is thus given in “The
Veterinarian” (1845, p. 626):

“ A cart-horse was brought here with a profuse flow
of white, clotty, and offensively smelling matter from
the off nostril. The external plate of the superior
maxillary bone on the same side was considerably
elevated, and pain was evinced on pressing the part.
There was no ulceration visible of the Schneiderian
membrane, but the submaxillary lymphatic glands
were somewhat enlarged. On examination there ap-
peared to be disease of the superior maxilla, in which
the grinder teeth were involved. Considering the
extent to which the facial bones were affected, it was
decided, as the only way of effecting a permanent cure,
to extract the diseased teeth. The horse was cast, and
by means of the ordinary tooth-key three of the upper
back teeth were extracted. In a few days after the
operation the discharge diminished in quantity, and
under the cofitinued application of proper remedies it
entirely subsided, and the horse is now well.

180 THE DENTISTRY OF THE TEETH.

“There are in this, as in former reports, cases where
the superior maxillary bone and its sinuses have been
injured from the elongation of the grinders of the in-
ferior maxilla, causing a nasal discharge in many cases
mistaken for that of glanders. ‘They are easily reme-
died by shortening the teeth with the cutting-forceps.”

Surgeon A. ree Santy says (“ Veterinarian,” 1875,
p. 835):

“On the 26th of June I bought a six-year-old mare.
She continued to work til! July 17th, when she was
suddenly taken with a slight running from the near
nostril, which greatly increased in twenty-four hours.
The submaxillary gland cn that side swelled. There
was slight tenderness of the throat and loss of appe-
tite, which soon passed away. I showed the animal to
a brother surgeon, and told him I thought of trephin-
ing. He said: ‘Don’t be in a hurry.’ It struck me
there might be something wrong with the grinders. I
examined them, and found the fourth superior near
side tooth with a depression on the outside and slightly
raised from the surface of the other teeth. There was
slight fetor from the food lodging there. I at once
cast the mare, and with some difficulty extracted the
tooth. I then dressed the wound and nursed the mare
for a few days. The discharge from the nostril ceased
in ten days. I have the mare now in constant work.”

The above case deserves consideration for several
reasons. Thousands of horses with precisely the same
symptoms have been killed because the surgeon could
not discriminate between diseased teeth and glanders.
The “slight tenderness of the throat and loss of appe-
tite, which soon passed away,” was the result of the pus

— Md :
°
“DON’T BE IN A HURRY.” 18}

finding an outlet, which gave partial relief. Surgeon
Santy acted on the advice, “ Don’t be in a hurry,” and
consequently had time to think. The depression on
the outside of the tooth and its slight projection above
the common level, were signs that the trained eye only
will detect. However, had the operation been delayed
for a short time, in addition to the depression on the
outside of the tooth, the gum would have been more
or less shrunken, and the tooth, as a natural conse-
quence, would have appeared longer.* Further, in-
stead of the tooth being “slightly raised from the sur-
face,” it might bave been below it; for, the inflamma-
tion having subsided, and the roots being shortened
by the caries, it is liable to be foreed deeper into the
socket. Its next natural movement, the caries having
destroyed its periosteum, is to drop out altogether.

As an offset to the foregoing cures, a few cases that
terminated in death will be given. Surgeon Samuel
Baker, in a letter to the editor of “The Veterinarian ”
(1845, p. 216), says:

“T was called in by a neighboring farmer to examine
a two-year-old colt, which had to all appearance a poly-
pus as large as a cricket-ball growing out of the right
nostril. Respiration through that nostril was stopped.
In order to ascertain its nature, I had the colt cast,
and found that the nostril was filled with a hard fleshy
tumor, which distended the other nostril also. After
making an incision through the ala and side of the
nostril, I removed a portion of the tumor, over a pound
in weight. But, as still no air passed through, and

* Shrinkatre of the gum, according to C. D. House, invariably
follows caries of the roots of the teeth.

182 THE DENTISTRY OF THE TEETH.

there scemed not the slightest chance of gaining a
passage, I ordered the colt to be killed.

“In dissecting the head I found that the cause pro-
ceeded from a decayed tooth, at the root of which was .
a bag of matter about the size of a walnut, which by
no possible means could relieve itself.”

Surgeon Baker does not say which of the six teeth
(of course it was an upper grinder of the right side)
was diseased. The complications of the case appear to
have been unusual, otherwise the bag of matter would
have sooner or later found an outlet through the nos-
tril. The extraction of the tooth would have probably
afforded an outlet through the alveolus; this failing,
the effect of trephining the sinuses should have been
tried.

Surgeon William Smith, of Norwich, Eng., reports
a case of caries of the roots of several grinder teeth,
accompanied by a discharge from the nostril, which
he admits he mistook for ozena. He says (“ Veterina-
rian,” 1850, pp. 381-2):

“JT was requested a few days ago to visit a horse
which was supposed to be ‘glandered.’ I found the
animal in a most emaciated and pitiable condition,
with a copious greenish and very offensive discharge
from the left nostril, with slight tumefaction of the
gland on the same side. There was no appearance of
ulceration, but the Schneiderian membrane had a
leaden, dirty hue. Taking all the circumstances into
consideration, I ordered the animal’s destruction, but
had its head sent to my infirmary.

“ Meeting Surgeon Gloag, of the Eleventh Hussars,
I told him I thought I had a case of ozena. He ex-

ONE TOOTH LOST AND FOUR DISEASED. 183

pressed a wish to be present at the examination of the
head, and I was glad to ayail myself of his assistance.

* A longitudinal cut was made on each side of the
septum nasi, and a transverse.one at a line between
the center of the orbits. Another longitudinal cut,
dividing the maxillary sinuses, was made just above
the roots of the grinder teeth on each side. By this
means we had an opportunity of examining the sep-
tum nasi on each side; also the turbinated bones, and
the frontal and maxillary sinuses.

“On the left side we found an accumulation of pul-
taceous food, covered with thick pus, completely filling
the maxillary sinus, and extending to the turbinated
bones. The frontal sinus contained an accumulation
of inspissated (thickened) pus, the septum nasi was of
a leaden hue, as also the membrane covering the tur-
binated bones, which was much inflamed and thick»
ened, but there was no appearance of ulceration.

“The difficulty was to ascertain how the food got
there. After careful search, it was very evident that
it could not have passed through the nostril. We
therefore gradually dislodged the food and matter,
searching for the former’s entrance, and at last found
a hole in the alveolar space belonging to the last
grinder, the root of which was completely gone, only
a small portion of the crown itself remaining. The
hole was sufficiently large to admit the little finger.
The mystery was solved—the process of mastication
had deposited the food in the sinus. The fourth
grinder was absent, having been lost evidently from
previous disease.

“On examining the right side of the head we found
the turbinatéd bones and membranes covering the
septum nasi comparatively healthy, but we discovered

184 THE DENTISTRY OF THE TEETH.

a cyst, about the size of a walnut, in the maxillary
sinus. It ‘contained limpid fluid, and occupied the
space immediately over the root of the fourth grinder
tooth, which was decayed and quite loose, and below *
the level of the other teeth. The teeth of the lower
jaw appeared healthy.”

Without further examination, Surgeon Smith sent
the head to the editor of “The Veterinarian,” who
Says:

“The mare (that being the sex according to the
teeth) we should take to have been about twenty vears
old. Her incisors are sound, and so are the grinders
of the lower jaw. But in the near (left) upper jaw,
the second, fourth, and sixth teeth are in a state of
progressive decay, and the same is true of the fourth
tooth of the off side. The vacuity caused by the de-
fective last grinder has opened a passage to the an-
trum, through which the food has passed, and thence
into the near chamber of the nose, between the tur-
binated bones, where it was discharged through the
nostril. This accounts for the irritation on this side
of the head, for the suppurated and even ulcerated
condition of the Schneiderian membrane, and for the
suspicious discharges. It was evident enough that -
there was no glanders. The very circumstance of ali-
mentary matter being discharged through the nostril
was enough to prove the contrary.”

Still another case of destroying a horse for what

merely appeared to be glanders is recorded by Prof.

* The italics are mine. Compare with commenis on Surgeon
Santy’s case, page 181.

A GOVERNMENT HORSE’S HARD LOT. 185

William Percivall in his work entitled “ Hippopath-
ology” (vol. ii, p. 237). He says:

“There are instances on record of carious teeth be-
ing productive of such evil consequences as ta lead,
through error, to a fatal termination. The following
relution ought to operate on our minds as a warning
in pronouncing judgment in cases of glanders, or at
least in such as assume the semblance of glanders:

“A horse, the property of government, became a
patient of Surgeon Cherry on account of a copious
defluction of diseolored and purulent matter from the
near nostril, unaccompanied by submaxillary tumefac-
tion, or by ulceration of the Schneiderian membrane.
For two or three months the case was treated for
glanders; but no improvement following, a consulta-
tion was deemed necessary, the result of which was
the horse was shot.

“On examination of the head, the third upper left
grinder proved to be earious, one-third of its root be-
ing already consumed and the remainder rotten. The
formation of an abseess within its socket had loosened
the tooth, and the matter flowing therefrom had estab-
lished a passage into the contiguous chamber of the
nose. The antrum was also in part obstructed by the
deposition of osseous matter.

“This is a case which, but for the inquisitiveness of
Surgeon Cherry, would have merged into that hetero-
geneous class of diseases passing under the appellation
of chronic glanders.

“My father’s museum contained several specimens
of carious teeth. One was that of a grinder, the inte-
rior of which was black and rugged, from being eroded
by ulceration, and the roots had from the same cause

186 THE DENTISTRY OF THE TEETH.

mouldered away. ‘Two others presented brittle exos-
toses upon their sides, forming spacious cavities within
and communicating with the contiguous teeth. One
of them exhibited a perforation through which pus
appeared to have issued. Both seemed to have been
cases which had originated in internal injury.”

Prof. George Varnell closes his series of papers “On
Some of the Diseases Affecting the Facial Region of
the Horse’s Head” (“ Veterinarian,” 1867), by giving
an account of a case of ‘osteo-sarcoma,’ the disease, in
his opinion, being caused by carious teeth. The case
illustrates the importance of veterinary dentistry ad-
mirably. He says:

“Further to illustrate varieties of the diseases of
the sinuses, I will relate,a case of osteo-sarcoma which
came under my care in July, 1862. I found the horse
had an offensive discharge from the left nostril. The
face below the orbit was enlarged, and the eye slightly
displaced in its cavity. I also found that the three
last grinder teeth in the upper jaw of the affected side
were quite loose in their sockets, from which a dis-
charge of a highly fetid character issued. Percussion
on the side of the face indicated extensive disease, and
the enlargement readily yielded to pressure. As there
was not the slightest prospect of a cure, I suggested
that the animal be killed.

“Post-mortem Hxramination—The outer walls of the
sinuses, which were very thin, were first removed, dis-
closing a mass of disease the seat of which was oppo-
site the roots of the fourth grinder tooth, which was
carious. This abnormal growth occupied the maxil-
lary, malar, lachrymal, and a portion of the frontal
sinuses, and had also encroached upen the orbit to

SWALLOWING A DISEASED TOOTH. 187

such an extent as to displace the eyeball. The outer
surface of the diseased mass was soft in texture. It
had a gelatinous appearance, and when pressed with
the blade of the scalpel, a thin, watery fluid oozed from
its surface. A section of it presented a grayish-red
appearance, with lightish streaks of fibro-osseous mat-
ter diverging from its roots and extending irregularly
through its entire substance. The facial bones them-
selves, in the region of the disease, had in some parts
disappeared altogether, while in others the cancelli
were much enlarged, their osseous partitions partially
absorbed, and their interstices filled with a deposition
of a fibro-cellular structure.

“Such is a brief outline of this malignant and in-
curable disease, which I have no doubt primarily arose
from caries of the roots of the grinder teeth.”

Prof. Renault, of Alfort, France, is the author of an
interesting account of a very unusual case, namely,
the swallowing of a diseased tooth by a horse, which
appeared originally in the “ Recueil de Médicine Vété-
rinaire” for 1836, It is an argument against casting
horses for the purpose of extracting their teeth, for
had the horse been in a standing position the accident
would not have occurred. When a horse’s head rests
upon the occiput, the muzzle pointing upward, it is as
natural—the tooth being free of the forceps as well as
the socket—for it to drop into the throat as it is for
water to run down hill. The full history of the case
is as follows:

“ A post-horse, seven years old, had not fed well, and
had been losing ‘flesh during about three weeks. On
the 26th of November, 1835, I saw him for the first
time. The postilion told me that within the last two

188 THE DENTISTRY OF THE TEETH.

days he had eaten with more difficulty and pain than
before, and dropped almost the whole of the hay and
corn from his mouth before it was perfectly masticated.
He had also observed that during the mastication of
his food the horse always inclined his head to the left
side.

“On examining the mouth, I easily recognized the
cause of this difficulty of mastication. The gum, at
the second grinder of the right lower jaw, was swollen
and ulcerated, both within and without. The least
pressure on the gum at this spot inflicted great pain,
and the animal also suffered when the crown of the
tooth was touched. On that portion of the jawbone
contiguous to the diseased tooth, was a considerable
swelling, hot and painful, which the postilion told me
had existed for about twelve days. It was increasing in
size every day. The breath was only slightly fetid,
and there was nothing to indicate caries of the tooth.
I expressed the opinion that the caries, if it existed, was
confined chiefly to the root of the tooth, and that the
ulceration of the alveolar septa beneath, of which there
was no doubt, rendered its extraction necessary.

“Qn the following day the horse was cast, and his
mouth being kept open by the proper instrument, the
key was applied to the tooth. It resisted my first
effort to draw it, but, on the second trial, gave way
with a peculiar sound, which made me suspect that it
was broken. The instrument (gag) was then taken
out of the mouth, in order that the tooth might
escape, but, to my great surprise, no tooth could be
seen, notwithstanding I carefully searched for it. It
was now plain that the tooth had been swallowed. I
then assured myself that the tooth had been entirely
extracted, and as, during the operation, the frenulum

—

OPENING THE JUGULAR. 189

of the tongue had been wounded, I deferred the cau-
terization of the alveolus till the following day.

“As to the swallowing of the tooth, I gave myself
very little concern. I did not think that so small a
body was likely to form any serious obstruction in the
intestinal canal, or that its temporary sojourn in the
large intestine could become at all dangerous; so I
merely directed that the mouth be frequently washed
with warm water, and forbade the use of hard food.

“26th. I again saw the horse, and no serious con-
sequence had yet followed the operation. He ate bar-
leymeal mash with appetite, and a small quantity of
hay. ‘Two hours afterward he was brought to the
School. He was very uneasy, and his belly was enor-
mously distended, the swelling being principally on
the right side, where the resonance was considerable
on percussion. The horse was continually endeavor-
ing to expel something from the anus, and the strain-
ing was so great that I feared the rectum would pro-
trude. The efforts were followed by small mucous
dejections, mixed with portions of food. The mucous
membrane was of a subdued red color. These symp-
toms had been preceded by swelling at the flanks;
colicky pains had followed, but they had ceased,
and nothing now remained except the enlargement of
the belly and the incessant effort to expel the feces.
The artery was full, but the pulse was almost imper-
ceptible; the extremities were cold and the mucous
membranes of a red violet color. The nostrils were
convulsively dilated, respiration difficult and acceler-
ated, and the walk staggering; the skin was covered
with sweat, and, in a word, the animal presented every
symptom of immediate suffocation. On this account I
immediately opened the jugular and abstracted about

190 » THE DENTISTRY OF THE TEETH.

twelve pounds of blood. The patient was very con-
siderably relieved. I then ordered all four legs to be
well rubbed with essential oil of turpentine.

“There now appeared to me a connection between
these symptoms and the swallowing of the tooth. But
where was this tooth? Entangled in the pyloric ori-
fice of the stomach? I could not perceive any symp-
tom of gastric disease. Was it in the convolutions or
the cacal portions of the small intestines? How then
could I explain the distention of the large intestines
and the expulsive efforts, so violent and continued ?
It was more likely that the tooth was lodged either in
the colon or the cecum, or in the irregularities of the
floating colon, and partially or entirely prevented the
passage of the feeces. It was hard to believe that in
the lapse of two days the tooth could have reached the
further part of the intestines.

“ Having determined on the nature of the disoase, I
was somewhat embarrassed to ascertain its precise seat.
I attempted to introduce my hand into the rectum,
but the cireumvolutions of the bowels were so much
distended with gas, and so completely filled the pelvis,
and the mere introduction of my finger caused such
violent efforts to expel the contents of the rectum, that
I was forced to desist.

“Tn the meantime the swelling rapidly increased,
and again threatened suffocation. 1 then determined
to use the only means in my power to prevent this,
namely, to puncture the cecum. This was effected
with the trocar used for hoove in sheep, and in an in-
stant the swelling subsided, and the symptoms of suf-
focation disappeared. I was then enabled to introduce
my hand into the rectum, but I could not discover the
situation of the tooth. While exploring the rectum,

THE TOOTH IN THE CCUM. 191

however, the ‘canula’ escaped from the eecum. The
swelling now began again, and increased with extraor-
dinary rapidity. Iwas about to plunge the troear into
the intestines once more, when I pereeived that all
treatment was useless. The animal was in the agonies
of death, and in a few moments it expired.

“Tbe post-mortem examination took place immedi-
ately after death. I found in the heart and lungs all
the lesions which usually accompany death by suffoca-
tion. The digestive canal was distended by gas. The
stomach was half filled with barleymeal, but not a par-
ticle of it was found throughout the whole extent of
the small intestines, nor was there the slightest trace
of inflammation of the mucous coat. The execum con-
tained a great quantity of blood-tinted fluid, but there
was no lesion or redness on any part of its internal
face to indicate the souree of the blood. Probably it
came from the wound made by the trocar.

“In the cavity of the ceeum, toward its point, we
found the tooth; but, I repeat it, there was no inflam-
mation of its mucous membrane. ‘There was, how-
ever, @ slight discoloration of the membrane toward
the end of the colon; it was of a slate color, and was
probably caused by the sulphuretted hydrogen gas.

“Are we to conclude that the death of the horse
was caused by the tooth? However extraordinary
such a conclusion may at first appear, | am very much
imclined to believe that it affords the best explanation
of the mystery. The horse had seareely eaten for
fifteen days. ‘This long fast had produced a compara-
tively empty condition of the digestive canal and an
augmentation of its irritability up to the moment of
the operation. The quietness of the horse and his
appetite aud ‘apparent health during the two days pre-

192 THE DENTISTRY OF THE TEETH.

ceding his death, proved that the tooth passed without
ovstacle through the first part of the intestinal canal.
Having arrived at the cecum, however, which was
almost empty, and lying for a greater or less time at
the inferior part of its mucous coat, its hard and irreg-
ular surface produced irritation; and as the contrac-
tions of this intestine were not effectual to seize the
tooth and return it to the beginning of the colon, the
prolongation of the irritation might suspend the diges-
tive function of this viscus, augment its s2cretions,
and cause the continual effort to expel the feces.
Hence also arose the gaseous distention of the abdo-
men. As to the death of the horse, the tooth was only
the indirect cause. The direct cause was suffocation,
which was produced by the distention of the bowels.”

Prof. Bouley and Surgeon Ferguson report two
fatal cases of swallowing teeth that came under their
own observation. “In the first,” they say, “the horse
succumbed in a tympanitic affection, accompanied by
extreme pain, and death was produced by asphyxia.”
The second case, judging by the short description of
it in “The Veterinarian” for 1844, is the identical
case just described by Prof. Bouley’s fellow-townsman,
Prof. Renault. Messrs. Bouley and Ferguson further
say:

“Such, however, is happily not always the result of
swallowing a tooth or the fragment of a tooth; but
even the possibility of such a result onght to make
the surgeon cautious. Moreover, the swallowing of a
tooth may cause serious consequences at some future
tuume. We refer to the formation of those productions
called ‘intestinal calculi.’ The tooth, on account of
its being indigestible, acts as the nucleus for the future

SWALLOWING A SOUND TOOTH. 193

calculus, as indeed may any similar body, which fact
has been demonstrated by Prof. Morton, of the London
Veterinary College, in an excellent paper on ‘The For-
mation of Calculus Concretions in the Horse.’” *

Surgeon W. A. Cartwright reports that he extracted
three grinders from a ‘quidding’ mare, one of which
she swallowed (‘‘ Veterinarian,” vol. iii, second series,
p- 277). The tooth was sound, which may account for
the favorable result of the case.

* The Enterprise, published in Virginia, Nevada, in its issue
for December 12, 1878, contains an article entitled “A Stone
found in a Horse’s Jaw,” which is in substance as follows: “ For
a long time a lump-has been noticed in the side of the jaw of a
horse belonging to Superintendent Osbiston, of the Gould and
Curry and Best and Belcher mines. It was near the jawbone,
and no liniment had power to soften or drive it away. Yester-
day a veterinary surgeon made an incision, and to his astonish-
ment removed a stone about two inches lone and one inch in
diameter. It is yellowish-white in color, and apparently as hard
as marble. Mr. M. M. Frederick, the jeweler, divided it longi-
tudinally, and in its center was what appeared to be a petrified
grain of barley, which was also divided longitudinally. Around
this nucleus the stone had formed in regular layers, the rings of
which could be distinctly traced. The material of which the
stone was composed appeared to de the same as that of the in-
crustations on the tubes of boilers. It is conjectured that the
grain of barley pierced the gum and imbedded itself in the flesh,
and that the saliva, flowing in, deposited limy matter similar to
that which is sometimes found on the teeth of horses as well as
men. Asmall concretion having thus been formed, it gradually
grew, the channel by which the grain of barley entered no doubt
remaining open and allowing an inflow of saliva.”

The above case is another proof that Dr. Dunglison was right
when he said that calculi “may form in every part of the animal
body.”

9

CHAPTER X.

FRACTURED) | JA WS

How Caused, and how to Distinguish an Abrasion of the Gums
from a Fracture of the Bone.—Replacing an Eye, Amputa-
ting part of a Lower Jaw, taking a Fractured Tooth and
Bones out through the Nostril, We.

FRACTURES of the jaws of the horse are of common
occurrence. They may exist independently, but they
are often complicated with and the cause of diseases of
the teeth. Caries of the jawbone proper, and even
some of the facial bones, is often communicated to the
alveoli, and when necrosis ensues the destruction of
the teeth is inevitable. This is as true in the case of
the horse as in that of man.

The rami (branches) of the lower jaw are common
seats of fracture, a frequent cause of which is the use
of sharp curved bits; but rough usage by the rider or
driver will now and then cause fractures even with a
smooth bit. As a rule, at first, the gums only are
affected; but in a short time the periosteum and bone
are reached. Prof. Varnell says: “Ifthe matter that
escapes be of a grayish-brown color and fetid, it will
indicate disease of the bone; but if it is from a sub-
cutaneous abscess, the discharge will be simply of a
purulent nature, and a speedy cure may be effected by
the application of very simple remedies.”

SURGEON FLEMING’S DISCOVERY. 195

~ When a fracture has been produced, inflammation

and fetor will follow, and the horse loses his appetite.
If the bone is removed and the horse is allowed to rest
for a few days, the wound will heal; otherwise the
most serious consequences may follow. The removal
of the bone may be effected sometimes soon after the
fracture; but if, after cutting into the gum, it be found
too firmly attached to the surrounding parts, it is bet-
ter to wait a week or two that nature may loosen it.
Bones an inch or more in length are often removed.
Thus that which at first appears to be “only a sore
mouth,” may, if neglected, prove the ruin of a valuable
horse.

Fractures are often caused by external violence. A
severe blow, accidental or otherwise, in the region of
the roots of the teeth may cause a fracture that will
necessitate the removal of both the bone and the teeth.

“The lower jaw,” says Prof. Youatt, “is more sub-
ject to fracture than the upper, particularly at the
point between the tushes and the incisor teeth, and at
the symphysis (of the chin) between the two branches
of the jaw. Its position, length, and the small quan-
tity of muscle covering it, especially anteriorly, render
it liable to fracture. The same circumstances, how-
ever, combine to render a reunion of the parts easy.”

The following extraordinary case of accidental frac-
ture is reported by Surgeon George Fleming (“ Veteri-
narian,” 1874, p. 694):

“Tn 1865, while stationed near Aldershot, I was
driving one day in the neighborhood of Farnborough,
When, in a narrow lane, our progress was somewhat
checked by a farmer’s wagon in front, which compelled
us to travel at a walking pace for some distance. Dur-

196 FRACTURED JAWS.

ing this delay my attention was attracted to the shaft
horse, which had an enormous tumor on the right side
of its face. It had such a singular appearance that I
dismounted from the carriage and induced the driver
of the wagon to halt, when I inquired into the history
of the case, and made an inspection of the tumor. It
was as large as half a good-sized cocoanut, occupied
nearly the whole side of the face, and was literally
a mass of what at first appeared to be fragments of
bone, but which, on a closer examination, proved to
be imperfectly developed grinder teeth. The tumor
looked as if it were composed entirely of them. I was
informed that, when two years old, the foal had taken
fright and ran away, and in trying to get through a
gate, a wooden stump ran into its face, making a large
hole. The hole filled up, the tumor gradually formed
on it, and since that time these ‘bits of bone, as the
wagoner called them, were constantly shed from its
surface. The growth was so large that the collar was
passed over the head with great difficulty. I was so
much interested in the case that I offered to keep the
animal while the removal of the tumor was attempted;
but the farmer could not spare it from work at the
time, and I did not have another opportunity.”

The following accounts of cases of fractured jaws
treated by various surgeons are from Prof. Youatt’s
work, “The Horse” (p. 445):

“Surgeon Cartwright had a mare in which the up-
per jawbone was fractured by a kick at the point
where it unites with the lachrymal and malar bones.
He applied the trephine, and removed many small
bones. The wound was then covered by adhesive
plaster, and in a month the parts were healed.

\

MM. REVEL AND BOULEY’S SKILI. 197

* Surgeon Clayworth reports the case of a mare that
fell while being ridden almost at full speed, and frac-
tured the upper jaw three inches above the corner in-
cisors. The teeth and jaw were turned, like a hook,
completely within the lower teeth. The mare was cast,
a balling-iron put into her mouth, and the teeth and
jaw pulled back to their natural position; she was then
tied so that she could not rub her muzzle against any-
thing, and was fed with bean-meal and linseed tea.
Much inflammation ensued, but it gradually subsided,
and at the expiration of the sixth week the mouth was
healed, scarcely a vestige of the fracture remaining.

“ An account of a very extraordinary fracture of the
superior maxillary bone is given in the records of the
Royal and Central Society of Agriculture in France.
A horse was kicked by another horse, fracturing the
upper part of the superior maxillary and zygomatic
bones, and almost forcing the eye out of its socket.
Few men would have dared to undertake a case like
this, but Monsieur Revel shrank not from his duty.
He removed several small bones, replaced the larger
ones, returned the eye to its socket, confined the parts
with sutures, slung the horse, and in six weeks he was
well.

“Surgeon Blaine relates that in treating a fracture
of the lower jaw he succeeded by incasing the entire
jaw in a strong leather frame. I have myself effected
the same object by similar means.

“Prof. Bouley says (‘ Recueil de Médicine Vétéri-
naire,” 1838) that he treated a horse whose lower jaw
had been completely broken off at the neck—that is,
at the point between the tushes and the corner incisor
teeth, the detached bone being held by the membrane
of the mouth.

198 FRACTURED JAWS.

“The horse was cast, the corner tooth on the left
side extracted, the wound thoroughly cleansed, and
the fractured bones brought in contact. Holes were
drilled between the tushes and the second incisors of
both jaws, through which brass wires were passed. -A
compress of tow and a ligature, the bearing-place of
the latter being over the tushes, surrounded the whole.
Thus the jaws were apparently fixed immovably to-
gether. The wires yielded somewhat to the struggles
of the horse, but the bandage of tow was tightened so
as to retain the fractured edges in apposition.

“The wound now began to exhale an infectious odor,
and gangrene was evidently approaching. M. Bouley
determined to amputate the fractured portion of the
jaw, its union to the main bone being apparently im-
possible. The sphacelated portion of the jaw was en-
tirely removed; every fragment of bone that had an
oblique direction was sawn away, and the rough por-
tions which the saw could not reach were rasped off.

“Before night the horse had recovered his natural
spirits, and was reaching for something to eat. On the
following day he ate oats, and no one looking at him
would have suspected that he had been deprived of his
lower incisor teeth. The next day he ate hay. Ina
fortnight the wound was nearly healed.”

C. D. House, veterinary dentist, performed an unu-
sual operation on a seven-year-old horse, the property
of Mr. J. T. Allen, of Hartford, Conn. In 1876 a
surgeon (2) made an incision in the right cheek and
knocked out a large part of the fifth upper grinder.
The violence of the operation fractured both the tooth
and the jaw, imbedding a large fragment of the former
in the bone above the socket. A year afterward, the

SKILL VERSUS BRUTALITY. 199g

horse still suffering and discharging matter from the
nostril, Mr. House was requested by Mr. Allen to ex-
amine and if possible cure him. He failed, however,
to discover the cause of the discharge, and it was not
till the expiration of another year that he determined
to probe the case to the bottom, the horse in the mean-
time having suffered as usual. Making an instrument
of the proper size and shape, he introduced it into the
nostril, seized the tooth fragment and drew it forth,
the horse at that instant making a deep expiration,
which blew out several fragments of bone and a part
of the root of the tooth. The animal made a good
recovery.*

* The Worcester, Mass., Spy for July 13, 1877, says: “C. D.
House, veterinary dentist, was in the city yesterday, operating
on the horses of the Hambletonian Breeding Stud. A case was
found where the grinders had been worn rough, and were be-
sides slightly displaced, so that the horse in eating lacerated the
lining of the cheek. Another case was where a colt’s temporary
tooth, after being partially forced from its place by the perma-
nent, had remained fastened by one root, and in such a position
as to injure the gum while the animal was feeding ; and yet so
nicely had the decaying tooth been lodged, that its presence was
only detected by the offensive odor. Several cases of inflamma-
tion of the gums were found, which were accounted for by the
presence of tartar. The tartar was removed.

“ Mr. House’s mode of operating is unique. He uses no gag,
and the animal stands free, He passes his hands over the teeth
of the most vicious horses, and was never yet bitten. He has

Nore.—In a paragraph of the above note that appeared in the first edi-
tion of this work, Dr. House, who now holds a diploma, advertised the
importance of dentistry by depreciating the importance of that great
scourge glanders, which Surgeon Fleming describes (1882) as a most repul-
sive, highly contagious, and incurable malady, very communicable between
the horse and agg species, less so between these and other species, man
also being frequently infected. Dr. Fleming says the disease was very
prevalent in London in the winter of 1882.

200 FRACTURED JAWS.

Lge |

Surgeon J. P. Heath thus describes a case of frac-
tured jaw (“ Veterinarian,” 1878, p. 288):

“In May last I was called to see a horse that had
been kicked by another horse. I found a transverse
fracture of the left side of the lower jaw, between the
first and second grinders, with lesion of the buccal
membrane. The bone protruded inward, the tongue
hung out of the mouth, and a constant flow of saliva
existed. The animal’s appetite was good, but there
was of course a total inability to masticate. The horse
was seventeen years old, but as the farmer (Mr. Gale,
of Exminster, Devon,) could ill afford his loss, I agreed
to try to cure him.

“T procured.a wedge-shaped piece of wood, six or
seven inches long by half an inch thick, which, after
fitting it between the branches of the jaw, I well be-
smeared with warm pitch and pressed it tightly be-
tween the fractured end of the bone. I then fixed
another piece of wood of the same length, but two
inches thick, which was also besmeared with pitch,
outside the fracture, placing a bandage six inches wide
over the whole, and tying it over Ke face below the
eyes.

operated on Edward Everett, Judge Fullerton, Emperor (owned
by 8. D. Houghton, of this city), and other notoriously vicious
horses.”

The statement about Mr. House’s mode of operating is strictly
true. His control cf a herse appears to be a gift. He never
confines a horse, not even in performing the operation of castra-
tion. Inan “interview” with a reporter of The New York Sun,
printed in 1877, in reply to the question, “ How do you know
when a horse has the toothache?” he said: “ He ¢e//s me that he
has it.” So Mr. House must understand “ horse-talk” as well as
horse-dentistry.

SURGEON HEATH’S SKILL. 201

“For the first fortnight I do not think the animal
took more than a gallon of the thin mashes and gruel
with which he was supplied; but af fter that time the
use of the muscles of the tongue began to return, and
he was able to swallow a little. In about three weeks
he could lick up oatmeal and oilcake gruel made thick,
and in less than a month I removed the bandage (al-
though the splints remained for six weeks), as by this
time he could swallow a little pulped mangold grass,
cut into chaff. For nine weeks he could only feed on .
cut fodder, when he was turned out to grass. At the
present time he is in perfect health, feeding on ordi-
nary diet and working constantly. The first and sec-
ond grinders, which were loosened, appear now to be
as firmly fixed as the others.”

The editor of “The Veterinarian” reports the case
of a pony that came near starving from having a stick
fastened in its mouth. No fracture of the bone was
produced, but the account of the case is worthy of in-
sertion here notwithstanding that fact, for it illustrates
a class of mishaps to which the horse is subject. He
says (“ Veterinarian,” 1855, p. 330):

“A pony was turned into a pasture, and was not
seen for several days. The owner found it standing in
a corner of the field, looking dejected and thin, with a
small quantity of viscid saliva escaping from its mouth. |
He took care of the pony for a few days, during which
time it took nothing but a little water, which it drank
with great difficulty. Our attendance was now re-
quested. Examination disclosed a stick about the size
of one’s finger, firmly wedged across the palate, be-
tween the corner incisors. Its pressure had produced

202 TREATMENT FOR ABRASED GUMS.

extensive sloughing, so that the bone was completely
exposed. ‘The pain was so great that the poor animal
stoutly resisted our efforts to remove the cause of its
sufferig. ‘This, however, was soon done, and the parts

eing cleaned with tepid water, were afterward dressed
with Tinct. Myrrhe. Little after treatment was nec-
essary beyond the daily application of the tincture, a.
mash diet, and the substitution of oatmeal gruel for
plain water.”

CHAPTER XI.
THE TEETH AS INDICATORS OF AGE.

Their various ways of Indicating Age.—The “ Mark’s” Twofold
Use.—The Dentinal Star.—Marks with too much Cement.—
Tricks of the Trade. —Crib-biting —Signs of Age Independ-
ent of the Teeth.

Tru incisor teeth of the horse, which, as before said,
differ “from those of all other animals by the fold of
enamel which penetrates the body of the crown, from
its broad, flat summit, like the inverted finger of a
glove,” indicate age (1) by their cutting; (2) by their
growth; (3) by their shedding; (4) by their marks ; *
(5) by their change of shape; (6) by their change of
color; (7) by their length, and (8) by the degree of
their outward inclination. The cutting, growth, and
shedding (of the tushes and grinders as well as the in-
cisors—the cutting and shedding occurring at com-
paratively regular periods, and the growth being grad-
ual), indicate age from birth til! about the sixth year;
the marks of the lower incisors from the sixth month
till the eighth year; those of the upper incisors, though

* Prof. C. 8. Tomes says “the mark exists in Hipparion, but
not in the earlier progenitors of the horse.” Prof. O. C. Marsh
says: “The large canines of Orohippus became gradually re-
duced in the’ later genera, and the characteristic mark of the
incisors is found only in the later forms.”

204 THE TEETH AS INDICATORS OF AGE.

perhaps less reliable, during the same period, and for
about four or five years longer (say the twelfth or thir-
teenth), and the change in shape,* color, and position
from about the seventh year tillold age. The change
in the shape of the teeth is caused by their wear and
growth, the wear counteracting the growth and the
growth the wear.

In foals and young horses the marks are probably
the surest guides by which to judge of the age. One
peculiarity of them is that, as the teeth wear down,
they approach the posterior edge. Besides their utility
in indicating age—being composed of enamel (the ad-
amantine substance)—they greatly enhance the dura-
bility of the teeth—that is, during the first third of

the horse’s life. As a rule the variations in the size

and appearance of the mark will be
as follows:

At six months they are oblong and
distinct in the centrals, and the
cavities are plain in the dividers.

At one year they are short in the
centrals, are becoming so in the di-
viders, but are large in the corners.

At a year and a half they are rep-
resented by a small spot in the cen-
trals, are diminished in the dividers,
but are still large in the corners.

At two years they are no longer
visible in the centrals (in some cases
are even shed); are smaller and
rounder in the dividers, but still

* Surg. Cherry says the shape and general character of the
teeth are better criterions of age than the marks.

ie

WHAT MAY PUZZLE A NOVICE. 20d

At two years and a half the centrals are shed; the
marks are faint in the dividers, but are distinct in the
corners. }

At three years the permanent centrals are nearly
grown; the marks in the dividers are just visible, and
haye become smaller in the corners.

At three years and a balf the marks in the centrals
are long and very distinct; the dividers are shed, and
the marks in the corners are faint.

At four years the marks in the centrals show the
effects of wear, but are still long and distinct; the per-
manent dividers are about grown, and the marks in
the corner teeth have almost disappeared.

At four years and a half the marks in the centrals
are still distinct, while those of the dividers are at
their best. The contrast between the large permanent
incisors and the small temporary corner teeth, which
have lost their marks, is striking at this age.

At five years the marks in the centrals are getting
smaller and rounder, but are large and distinct in the
dividers; the corners are usually shed at this age.

“At six years,” says Prof. Youatt, “the marks of
the central nippers are worn out. There will, however,
still be a difference of color in the center of the tooth.
The cement filling the hole made by the dipping of
the enamel will present a browner hue than the other
part of the tooth. It will be distinctly surrounded by
an edge of enamel, and there will remain even a little
depression in the center, and also around the case of
enamel; but the deep holes in the center of the teeth,
with the blackened surface which they present, and
also the elevated edge of enamel, will have disappeared.
Persons little accustomed to horses are often puzzled
here. They expect to find a plain surface of uniform

206 THE TEETH AS INDICATORS OF AGE.

color, and know not what conclusion to draw when
they see both discoloration and irregularity.” The
marks in the dividers are much reduced in size, but
those of the corner teeth are large and distinct.

At seven years the marks disappear from the divider
incisors, and at eight from the corner teeth.

Monsieur Girard thus describes the changes in shape
of the incisors, referring also to the disappearance of
the marks in the upper teeth:

* At nine the central incisors become rounded, the
dividers oval, and the corner teeth narrower. The cen-
- tral enamel (mark) diminishes and

é i Hy approaches the posterior edge.

ie “At ten the dividers are rounder,
and the central enamel is very near
the posterior edge and rounded; at
eleven they have become rounded, and
the enamel has disappeared.

“At twelve the corner teeth are
rounded. The yellow band is larger,
and occupies the center of the wear-
ing surface.

“At thirteen all the lower incisors
are rounder; the sides of the centrals
are becoming longer. The central
enamel remains in the upper corner
teeth, but is round and approaching
The forms successive. the posterior edge.

s dbythed 1 =
Bed re a Os Prien “ At fourteen the lower central in-

sequence of friction.—A, Z “
Chauvea. cisors have a triangular appearance;
the dividers are becoming long at tneir sides.

“At fifteen the central incisors are triangular, and

the dividers are becoming so.

CAUSE OF THE YELLOW COLOR. 207

* At sixteen the dividers are triangular, and the cor-
ner teeth are becoming so.

“ At seventeen the corner teeth, like the dividers and
centrals, have become triangular, the sides of the tri-
augles being equal.

“At eighteen the lateral portions of the triangles
lengthen in succession—first in the centrals, next in
the dividers, and then in the corners; so that at nine-
teen the lower centrals sre flattened from one side to
the other; at twenty the dividers are flattened, and at
twenty-one the corners also are.”

The three following extracts give some idea of the
difficulties to be encountered in judging the age by
the teeth. Prof. Youatt says:

“Stabled horses have the marks sooner worn out
than those at grass, and a ‘crib-biter’ may deceive the
best judge by one or two years. At eleven or twelve
the lower nippers change their original upright posi-
tion and project forward. They become of a yellow
color, the cause of which is that the teeth grow to
offset their wear; but the enamel which covered their
surface when they were young cannot be repaired, and
that which wears this yellow color in old age is the
part which was formerly in the sockets. The gums
recede and waste away, and the tushes wear to stumps
and project outward.”

Surgeon Ewd. Mayhew says (“The Horse’s Mouth:
Showing the Age by the Teeth”):

“That the teeth of the horse denote age appears to
have been a very ancient belief, which the experience
of centuries has not changed. Within certain limits

208 THE TEETH AS INDICATORS OF AGE.

the belief is well founded, for perhaps no development
is mere regular than the teeth of the horse, and no
natural process so little exposed to the distortions of
artifice. We are, nevertheless, not to expect that the
animal carries in its mouth a certificate of birth, writ-
ten in characters so deep that they cannot be obliter-
ated or misinterpreted. He who would judge of the
age by the teeth must study them, and be prepared to
encounter difficulties. In proportion as he has done
the one, and is enabled thereby to overcome the other,
will be his success. The qualified judge alone will
read the teeth correctly. He will make allowance
where certain marks are indistinct or absent, and he
will be cautious in pronouncing an opinion. The vet-
erinary practitioner knows that the teeth are worthy
of attention, and he feels that their indications, scien-
tifically interpreted, will seldom mislead.”

Surgeon J. H. Walsh, in his excellent work, “The
Horse; in the Stable and in the Field,” says:

“Tn order to be able to estimate the.age of the horse
by his teeth, it is necessary to ascertain, as nearly as
may be, the exact time at which he puts up his milk
teeth, and also the periods at which they were replaced
by the permanent. Finally it becomes the province
of the veterinarian to lay down rules for ascertaining
the age from the degree of attrition which the perma-
nent teeth have undergone. For these several purposes
the horse’s mouth must be studied from the earliest
period of his life up to old age.”

Judging the age by the teeth is even more compli-
cated and difficult than is shown by the foregoing ex-
tracts. Among other complications worthy of consid-
eration are the following:

LIKE CREEDMOOR MARKS, HARD TO HIT. 209

About the ninth year a mark, which is sometimes
mistaken for the infundibulum, appears on the central
incisors. Girard named it the dentinal*
star, but it is also called the fang-hole
and secondary mark. Dentinal star is
perhaps the most proper name, for the
mark is “due to the presence of second-
ary dentine, into which the remains of
the pulp has been converted.” The con-
version of the pulp into dentine prevents
the cavity from becoming a reservoir for food, for
otherwise it would become such as soon as reached by
wear ; and it preserves the tooth from decay, afferd-
ing a good illustration of Nature barricading disease.
The pulp cavity is lined with dentine ; the dentine
into which the pulp is converted is sometimes called
osteodentine, and may be distinguished from the for-
mer by its yellow tint. The star may not afford reli-
able data by which to judge of the age, but its pres-
ence is prima facie evidence that the tooth has been
worn to the original pulp cavity.{ It becomes plainer
as it approaches the cavity’s center, but the bottom
of the cavity is ultimately reached, which of course is
hollow. It is visible 8 or 10 years, the depth of the
cavities varying from about 3 to 1 inch.

The marks of some teeth are disproportionately
composed of cement, a fact Prof. A. Chauyeau says he
is not aware has ever been taken into account in “‘ cal-

* See note, page vili.

+ Nature fills the cavity in proportion as the erown is worn.
Take two teeth of the same kind, one just full-grown, the
other worn almost to its neck. In the latter the spot is visible,
and if as much material is cut from the former as has been worn
from the latter, its cavity will be cat through.—Jvhn Hunter.

210 THE TEETH AS INDICATORS OF AGRE.

culating the progress of wear.” Such teeth would soon

wear out, for there is as much difference in the density
of cement and enamel as between cartilage and bone.

The obliteration of the mark may be hastened in a
small or medium-sized tooth by the friction of one that
is abnormally large, while a stunted or dead tooth may
never lose its mark.

The more upright the teeth the faster they wear. It
is said that the crowns will be worn to the extent of a
quarter of an inch between the fifth and sixth years
(when they are most upright), while only about that
quantity of material will wear away between the twen-
tieth and twenty-fifth years.

A horse’s food is a matter also to be taken into ac-
count. The mastication of grass, carrots, turnips,
potatoes, bread, &c., does not cause much wear to the
teeth. However, when grass is procured by grazing.
the incisors suffer much friction—caused, not by the
grass, but by the teeth grinding one another, for they
meet edge to edge, and are employed in this oeccupa-
tion for hours, whereas a “feed” of corn is shelled in
afew minutes. In the former case the incisors suffer
great friction; in the latter, the grinders. Again, it is
said that “horses fed on salt marshes, where the sea-
sand is washed among the grass, or on sandy plains or
meadows, are affected by the increased friction of their
teeth.” But no matter how soft a horse’s food may
be, if he is addicted to the vice called “ erib-biting,”
his teeth may be ruined before those of the corn-fed
horse have even Jost their marks.

Several trade tricks are also to be noted. Of “bish-
oping,” Prof. Youatt says:

“ Dishonest dealers resort to a method of imitating

YOUATT’S COMPLIMENTS TO BISHOP. 211

the mark in the lower nippers. It is called Bishoping,
from the name of the scoundrel who invented it. The
horse of eight or nine years is thrown, and with an
engraver’s tool a hole is dug in the now almost plain
surface of the corner teeth, its shape resembling the
mark in those of a seven-year-old horse. The hole is
then burned with a heated iron, and a permanent
black stain is left. The next pair of nippers are some-
times lightly touched also.

« An unprofessional man would be easily deceived by
this fraud, but it cannot deceive the trained eye of the
horseman. The irregular appearance of the cavity,
the diffusion of the black stain around the tushes—
the sharp points and concave inner surface of which
can never be given again—the marks on the upper nip-
pers, together with ti general conformation of the
horse, vil prevent deception. Moreover, in compar-
ing the lower with the upper nippers, unless the oper-
ator has performed on the latter also, they will be
found to be considerably more worn than the lower,
the revers2 of which ought to be the case. Occasion-
ally a clever operator will burn all the teeth to a prop-
erly regulated depth, and then a practiced eye alone
will detect the imposition.” *

* RouGH ON THE Rousstans.—Surgeon John C. Knowlson
makes the following open confession (“The Complete Farrier,
or Horse Doctor,” p. 150): “I was hired by Anthony Johnson,
of Wincolmlee, Huil, as farrier to a number of horses that were
going to Moscow, Russia. We hada little gray, seventeen-year-
old horse, named Peatum, whose mouth I bishoped. He passed
for six years old, was the first horse sold, and brought £500,
English money! I only mention this asa caution to hérsemen.”

Surgeop Knowlson could have evidently beaten the late Pres-
ident Lincoln in a (wooden) horse trade.

212 THE TEETH AS INDICATORS OF AGE.

Of a deception practiced by sellers of two-year-old
foals, namely, passing off an early two-year-old for a
late three-year-old, Prof. Youatt says:

“The age of all horses used to be reckoned from
May, but. some are foaled as early as January. A two-
year-old foal of the latter date may, if it has been well
nursed and fed and has had its central nippers drawn
(that three or four months’ time may be gained in the
appearance of the permanent), be sold at the former
date for a three-year-old. ‘To horsemen, however, the
general form of the animal, the little development of
the forehand, the continuance of the mark in the divi-
der nippers, its more evident existence in the corner
ones, and some enlargement or irregularity about the
gums, from the violence used in for¢ing out the teeth,
are a sufficient security against deception.”

Anc again of four-year-old foals:

“ Now, more than at any other time, will the dealer
be anxious to put an additional year upon the animal,
for the difference in strength, utility, and value be-
tween a four-year-old colt and a five-year-old horse is
very great. But the lack of wear in the central and
divider nippers, the small size of the corner ones, the
little growth of the tushes, the low forehand, the leg-
giness of the colt, and the thickness and little depth of
the mouth, will at once detect the cheat.”

The following is Prof. Youatt’s description of crib-
. biting and its effect on the teeth (“The Horse,” pp.
511, 519):

‘“‘'The horse lays hold of the manger with his teeth,
violently extends his neck, and then, after some con- —

COLICKY CRIB-BITERS. 213

vulsive action of the throat, a slight grunting is heard,
accompanied by a sucking in of air. It is not an effort
at simple eructation, arising from indigestion, but is
merely the inhalation of air. It takes place with all
kinds of diet, and when the stomach is empty as well
as when it is full.

«The effects of crib-biting are plain enough. The
teeth are worn away and occasionally broken, and in
old horses to a very serious degree. Sometimes graz-
ing is rendered difficult or almost impossible. Corn is
often wasted, for the horse will frequently ‘crib’ with
his mouth full of it, and the greater part of it will fall
over the edge of the manger. Much saliva escapes also,
which impairs digestion. Crib-biting horses are more
subject to colic than others, and to a species difficult
of treatment and frequently dangerous.

«The only remedy is a muzzle, with bars across the
bottom sufficiently wide to allow the horse to pick up
his corn and pull his hay, but not to grasp the edge of
the manger. Some recommend turning out for five or
six months; but this will never succeed except with
young horses, and rarely with them. The old crib-
biter will substitute the gate for the manger. We have
often seen him galloping across the field for the mere
object of having a gripe ata rail.”

Prof. Youatt further says that the vice is a species
of unsoundness, having been so decided in the courts.
It is often the result, he says, of imitation, but oftener
the consequence of indigestion. Mischief, he says, is
another cause of it.

The mouth, it is said, is broader at seven years -of
age than at any other time; but, so far as judging the
age is concerned, this fact (assertion) is of little prac-

214 THE TEZTH AS INDICATORS OF AGE.

tical use. The facts that follow, however, are of more
or less use, and are worthy of perusal. Prof. Youatt
says:

“The indications of age, independent of the teeth,
are deepening of the hollows over the eyes; wrinkles
over tne eyes and about the mouth; gray hairs, par-
ticularly over the eyes and about the muzzle; the
countenance and general appearance; thinness and
hanging down of the lips; sharpness of the withers;
sinking of the back; lengthening of the quarters, and
the disappearance of windgalls, spavins, and tumors of
every kind. * * * At nine or ten the ‘bars’ of
the mouth become less prominent, and their regular
diminution will indicate increasing age.”

Of another deception Prof. Youatt says:

“We form some idea of the age of the horse by the
depth of the pits above the eyes. There is at the back
of the eye a quantity of fatty substance, on which it
may revolve without friction. In aged horses, and in
diseases attended with general loss of condition, much
of this disappears. ‘The eye becomes sunken, and the
pit above it deepens. Dishonest dealers puncture the
skin, and, with a tobacco-pipe or tube, blow into the
orifice till the depression is almost filled. This, with
the aid of ‘bishoped’ teeth, may deceive the unwary.
The fraud may be easily detected, however, by press-
ing on the part.”

“Frank Forester” (William Henry Herbert), says
(“' The Horse of America,” vol. i, p. 72):

“Much stress is laid by many persons on the depth
of the supra-orbital cavities, and more yet on the length
and extreme protrusion of the nippers beyond the

~

Pliny did not compile Varro (B. C. 116) and
Columella (A. D. 42) carefully. Varro (Book IL,
Cap. VIL.) says: “It is by the teeth that they find
out the age of a horse.” He then describes the
shedding of the teeth, concluding as follows: “Others
erow in their place, which, hollow at first, fill up in
the sixth year,” etc. The error about the cavities
filling up stands to this day. Unlike the pulp cavi-
ties, they are not filled by nature with tooth ma-
terial; they are obliterated by wear. Columella
(Book VL, Cap. XXIX.) not only describes the
marks, but the shedding of the molars also. In

Latin he says: “ Jntru sextum deinde annum, molares

superiores cadunt.” So the error of Aristotle about
the non-shedding of the molars did not stand tili
the sixteenth century. (See page 69.) Palladius
(about A. D. 400) and Vegetius (about the same
time) describe both the marks and the shedding of
the molars. Vegetius speaks of the wrinkles in the
upper lip, the number of wrinkles indicating the

number of years, and also the black spots in the
middle of the teeth about the twelfth year. In con-
clusion he says: “Finally, the number of wrinkles,
the sadness of the countenance, the stupor of the
eyes, the baldness of the eyelids, the dejection of
the neck, and the lassitude of the whole body indi-
cate age.” (Book IV., Cap. V.) I have never seen
what could be called a description of the wrinkles in
any other book, but my attention was called to them
by Dr. Wm. Wilson, of Jersey City, N. J., in 1881.
Vegetius Renatus, Publius, is often confounded with
Vegetius Renatus, Flavius, a military author. Ve-
vetius wrote on veterinary Science ; Varro, Columel-
la and Palladius on agriculture. Fragments of the
works of Apsyrtus (or Absyrtus), the Greek veter-
inarian (about A. D. 330), are extant, but I have
never seen anything of his on age. He described
slanders, fevers, epizootic influenza, dental cysts,
ete. (See JOURNAL OF COMPARATIVE MEDICINE AND
Suraery for January, 1884, page 19.)

SPANISH HORSES AND MULES—ANCIENTS. 215

gums, as also on hollowness of back. I have seen colts
—got by aged stallions—having all these indications
of age before they had a full mouth; and with cavities
and hollow backs before they had got colt’s teeth.”

Surgeon Brandt, who thinks shape indicates age as well after
the eighth year as marks do before, says (“ Age of Horses”) :-—
“Some breeds, the Spanish for instance, require a longer time
to develop than others. The bones appear to be harder, the
teeth change somewhat later, and wear more slowly; some-
times, after the fifth year, they appear one or two years younger
than they are. The age of crib-biters can be told by the corner
teeth, which are seldom injured. Should this be the case, how-
ever, add as many lines as are needed to make them the natural
length. The horse is as many years younger as the teeth are
lines too short. The front teeth are frequently worn away
earlier when horses have been fed on unshelled corn,

“The age of mules cannot be ascertained with the same ac-
curacy as that of horses, After their eighth year they usually
appear younger than they are.” ;

Note.—C. F. Hoeing. M.R.C V.S. (Jersey City, N.J.) says the fact that the
marks indicate age was discovered by Prof. Pessina of Vienna in 1818-20.
The ancients appear to have known nothing about the marks. Aristotle
(His. Animals, Boln’s trans., pp. 170 1) says that before casting its tecth a
horse has its mark, but not afterward. After casting them age is not easily
told, but is usually ascertained by the canines, which in riding-horses are
generally bit-worn ; these teeth are called the marking teeth. (That is they
are marked by wear. They have no natura? marks. See p. 69.)
Xenophon, who finds use for tushes in bridling a horse—pressing the lip
agiinst them—says that in buying a horse, “to avoid being cheated, let it
not escape notice what his age is; if he has not the foal teeth, he can neither
give pleasure with anticipated exertion nor be easily disposed of.’ (p. 719.)
Pliny says age is indicated by the eruption and shedding of the incisors
(giving accurate dates); then by the projecting of the teeth, the grayness
of the eyebrows, and the depth of the pits around them. (Vol. iii. p. 60.)
Pliny compiled from Varro, Columella, and many others. Would they
all fail to mention the marks if they knew anything about them ?
Erroneous and Extraordinary Statements by Pliny.—¥Worses’ teeth grow
whiter with age. Ifa horse is geided before it changes its teeth it never
sheds them. No animal sheds the molars. Men have more teeth than
women. All men, except the Turduli, have 32 tecth. Some persons have 3
continuous bone in place of teeth. Human tecth contain venom ; they tar-
nish a mirror and kill unfledged pigeons. Zocles had a set of teeth at 104.

GHAPTER: X11:
THE TRIGEMINUS OR FIFTH PAIR OF NERVES.

Its Nature and the Relation it bears to the Teeth.—Its Course in
the Herse and in Man.

Tue thread-like nerves of the teeth are derived frorn
the superior and inferior maxillary branches of the
trigeminus or fifth pair of nerves. In the horse these
branches are four or five times as thick as a rmbbon
and about five-eighths of an inch wide. The ophthal-
mic branch is smaller and shorter, its course extend-
ing only from the brain to the eye, while that of the
two former extends te the lips, running parallel to and
about an inch from the roots of the grinder teeth.*

The description of the trigeminus and its course is
from a lecture by Prof. Youatt to veterinary students,
and may be found in “The Veterinarian” for 1834
(p. 121). In the first part of the lecture the nature of
tue trigeminus—its double origin and function—is
expatiated upon, a summary of which is that the sensi-
tive and motor roots, are contained within the same
sheath; that the sensitive root is so much larger and
its fibrils so much more numerous than the motor that

* For the preparation of an anatomical specimen showing the
general course of the trigeminns, I am indebted to Prof. J. M.
Heard, of the New York College of Veterinary Surgeons.

THE TWO ROOTS. 217

it may still be called the sensitive nerve of the face ;
that the trigeminus is the only nerve of the brain that
bestows sensibility to the face, except a few branches
from the cervicals, which may be traced to the lower
part of it; that there are some anatomical facts which
incontestably prove that the motor nerve exists: that
Sir Charles Bell laid the root of the trigeminus bare in
an ass immediately after the animal’s death, and that
on irritating the nerve the muscles of the jaw acted
and the jaw closed; that he divided the root of the
nerve in a living animal, and the jaw fell;* that he

* “ RE-ESTABLISHMENT OF SENSIBILITY AFTER RESECTION
OF NERVES.—A memoir by MM. Arloing and Tripier was read
before the French Academy, November 28th, on the effect of re-
section of certain nervous trunks. Clinical facts have several
times shown that after wounds which have altered or destroyed
a portion of a nerve, sensibility returns in the integuments to
which the nerve is distributed. MM. Arloing and Tripier made
nervous resections in dogs, and saw sensibility reappear after a
certain time in the integuments to which the branches of the
nerve were distributed, and in the peripheral end of the nerve
itself.”— Popular Science Review, 1867.

“How Moror-NervES END IN NON-STRIATED MUSCULAR
TissuE.—A very valuable communication stating the results of
M. Hénocque’s researches has been published in “l Archives de
Physiologie,” and may be thus abstracted: 1. The distribution
of the nerves in smooth muscle is not only identical in man and
other vertebrate animals in which it has been observed, vut is
essentially similar to all the organs containing smooth muscle.
2. Before terminating in the smocth muscle, the nerves form
three distinct plexuses or networks—() a chief or fundamental
plexus, containing numerous ganglia, and situated outside the
smooth muscle; (b) an intermediate plexus ; and (c) an intra-
muscular plexus, situated within the fasciculi of smooth fibers.
8. The terminal fibrils are everywhere identical. They divide
and subdivide dfthctomously, or anastomose, and terminate by
a slight swelling or knob, or in a punctiform manner, The ter-

10

218 THE FIFTH PAIR OF NERVES.

divided the superior maxillary branch on both sides,
the animal losing the power of using the lips 5 that
Mr. Mayo divided the root of both the superior and
inferior maxillary, the result being that the lips no
longer remained in perfect apposition, and the animal
ceased to use them in taking up his food; that the
sensitive root, or a portion of it, after entering the cav-
ernous sinus, swells out into or passes through a gan-
glion, and that the motor root can be traced beyond
the ganglion, uniting afterward with its fellow and
forming the perfect nerve; that the ganglion, being
composed of sensitive fibrils only, resembles a brain.

minal swelling appears to occupy different parts of the smooth
muscular fiber, but most frequently to be in the neighborhood
of the nucleus, or at the surface of the fibers, or, lastly, between
them.”—The Montiily Microscopical Journal, 1870.

“STRUCTURE OF NERVES.—M. Roudanoosky says that the
primitive elements of nerves are tubes having a pentagonal or
hexagonal configuration, As to their constitution, he says that
every nerve has a substratum of brain-matter, and also of the
spinal marrow, and probably of the ganglionic matter also. The
gray matter, he says, is the fundamental nervous substance, and
plays the principal part in the functions.”—“ Veterinarian,”
1865, p. 313.

In a letter to his brother, G. J. Bell, written in 1807, Sir
Charles says: “I consider the organs of the outward senses as
forming a distinct class of nerves. I trace them to correspond-
ing parts of the brain, totally distinct from the origin of the
others. I take five tubercles within the brain as the internal
senses. I trace the nerves of the nose, eye, ear, and tongue
to these. Here I see established connection ; there, the great
mass of the brain receives processes from the central tubercles.
Again, the great masses of the cerebrum send down processes
or crura, Which give off all the common nerves of voluntary mo-
tion. I establish thus a kind of circulation, as it were.”—Medi-
cal Gazette.

THE COURSE OF THE NERVE. 219

Prof. Youatt’s description of the course of the tri-
geminus is as follows:

“The trigeminus has been described as springing
by a multitude of filaments from the crura cerebelli,
and forthwith running for safety into the cavernous
sinuses, and there suddenly enlarging into or passing
through a ganglion. The nerve, as its name implies,
divides into three parts, the division taking place in
the cavernous sinus, after the superior or sensitive
root has been joined by the inferior or motor root.
Each part, before it leaves the cranium, assumes a dis-
tinct investment of dura mater. The branches are
named, from the parts to which they are destined, the
Ophthalmic, the Superior Maxillary, and the Inferior
Maxillary.

“The ophthalmic is the smallest of the three. It is
formed within the sinus, where it is in conjunction
with the superior maxillary, which it soon leaves, and,
passing through the foramen Jacerum into the orb‘t,
subdivides and forms three distinct branches—the
Supra-orbital (the frontal), the Lachrymal, and the
Lateral Nasal (the nasal). The supra-orbital climbs
behind the muscles of the eye, giving filaments to the
rectus superior and the superior oblique, and some
also to the fatty matter of the eye. The main branch,
escaping through the superciliary foramen, is soon lost
in ramifications on the elevator of the superior eyelid,
the integument of the forehead, and the periosteum.
The lachrymal, as its name implies, is chiefly concerned
with the lachrymal gland; a few ramifications, how-
ever, are sent to the conjunctiva and also to the ciliary
glands of the upper eyelid, while a distinct twig of it
passes out at the angle between the zygoma and the

80g THE FIFTH PAIR OF NERVES.

¢
frontal orbital process, where it anastomoses with the

supra-orbital and with ramifications from the superior
maxillary. It is also lost on the integument and
muscles of the forehead. The lateral nasal is the
largest of the three. Almost at its beginning we ob-
serve the filaments that help to form the Ophthalmic
Ganglion. They are more numerous and more easily
traced in some of our domesticated animals than in
others, and the ganglion itself is differently developed,
but for what physiological purpose I know not. It is
comparatively larger in the ox than in the horse, and
sends more filaments to the iris. Four distinct fila-
ments may be traced in the ox, but seldom more
than two in the horse or the dog. ‘To these fila-
ments others of the ophthalmic, that have not passed
through the ganglion, afterward join themselves; so
that the ciliary are also minute compound nerves of
motion and sensation.*

* «The best account, however, of this is given by Dr. Jonas
Quain (‘Quain’s Anatomy,’ p. 768). He considers the ganglion
as a center of nervous influence—a little brain, as it were—and
the filaments which some anatomists describe as composing, he
speaks of as branches given out from it. ‘It lies,’ says he,
‘within the orbit, about midway between the optic foramen and
the globe of the eye, and is inclosed between the external rectus
muscle and the optic nerve. It is exceedingly small and, owing
to its being imbedded in the soft adipose tissue which fills the
interstices of the different parts within the orbit, difficult to find.
Its branches are the following: From its anterior border from
sixteen to twenty filaments issue, which proceed forward to the
surface of the sclerotic, and pierce it through minute foramina.
These are the ciliary nerves. In their course to the globe of the
eye they are joined by one or two filaments derived from the
nasal nerve, but they do not form a plexus (an interlacement).
They become, however, dispersed or divided into two fasciculi,
one above and the other below the optic nerve, the latter being

THE OPHTHALMIC NERVE. 221

“The ophthalmic nerve, after running between the
rectus superior and the retractor muscles, gives a

the more numerous. They pass between the choroid membrane
and the contiguous surface of the sclerotic—lodged in grooves in
the latter—and on reaching the ciliary ligament, pierce it, a few
appearing to be lost in its substance, wiile all the rest pass in-
ward and ramify in the iris. From the posterior border of the
ganglion, which seems as if terminated by two angles, two
branches issue, one of which passes backward and upward to
the nasal branch of the ophthalmic nerve, appearing to be the
medium of communication between the ganglion and the rest of
the ganglial system, by being prolonged to the carotid plexus.
The other, the shorter branch, passes downward and backward
to the inferior oblique branch of the motor nerve of the eye.’

“For my own part,” says Prof. Youatt, “I am now disposed.
to be very much of Dr. Quain’s opinion. It was not fitting that
the motions of the iris should be under the control of the will—
they should respond to the varying intensity of the light.”— W.
Youatt in “Veterinarian” for 1836, p. 49. ;

Mons. Cuvier says: “ It divides into two ramifications, one of
which proceeds toward the optic, unites with the small branch
of the third pair, and by this union produces a nervous enlarge-
ment called the lenticular or ophthalmic ganglion. This gan-
glion usually sends off the ciliary nerves, disposed in two bun-
dles. They are each composed of several filaments, which enter
the globe of the eye obliquely. The iris receives a great num-
ber of small ramifications from the ciliary nerves, which, after
having perforated the sclerotic and passed around the choroides
longitudinally, like ribbons, but without penetrating it, are lost.”
—“Comparative Anatomy,” Vol. II, p. 206.

Prof. W. Percivall says: ‘‘ Upon the outer side of the optic
nerve, between it and that part of the motor oculi from which
the branch nerves spring, is situated the ophthalmic ganglion.
This little body is principally constituted of branches from the
third pair, but it receives a filament or two from the sixth. The
nervous threads transmitted by the ganglion surround the sheath
of the optic nerve, and pursuing their course over it, penetrate
the globe of tlie eye, and run to be dispersed upon the iris.”—
“Anatomy of the Horse,” p. 336.

222 THE FIFTH PAIR OF NERVES.

branch to the ‘membrana nictitans,’ and then takes a
singular course. Some ramifications go to the frontal
sinuses and the foramina, and, piercing the orbit of
the eye for this purpose, present a beautiful view in
young animals, particularly the sheep. The main
branch then enters the cranium again through the
internal orbital foramen, passes under the dura mater,
returns through the cribriform plate, and ramifies on
the membrane of the nose, sending some branches as
low as the false nostril and ale.

“The superior maxillary nerve, or second branch of
the trigeminus, contains little that is peculiar to or
has a practical tendency in quadrupeds. The different
situation and conformation of the bones of the face
cause the principal or only variation in the distribu-
tion of this branch in the biped and the quadruped.
It leaves the cranium through the foramen rotundum,
and at the base of the skull gives off small ramifica-
tions to the inner canthus of the eye, the antrum, and
the two posterior grinder teeth. It also supplies the
lateral portion of the nasal cavity through the spheno-
palatine foramen, while filaments are given off from
the origin of the trunk .to the temporal muscle. A
branch also runs along the upper border of the septum
nasi to the palate, and a larger branch, which tray-
erses the palate In company with its blood-vessels,
passes through the foramen incisivum to the upper
lip. The matin trunk of the nerve now enters into the
superior and exterior foramen, in the hiatus between
the palatine bone and the tuberosity of the superior
maxillary bone, leading into a bony canal (easily traced
in the horse) between the maxillary sinus and the an-
trum, and appearing as a great pillar passing through
the palatine sinuses in the ox. It traverses this canal,

THE GOOSE’S FOOT. Roo

and at length emerges on the face through the fora-
men infra-orbitarium, and under the levator labii su pe-
rioris muscle. It no sooner escapes from this canal
than it forms the ‘pes anserinus’ (the goose’s foot, for
it divides something like the foot of this bird). It
anastomoses with or receives numerous branches from
the seventh pair, and forms an intricate plexus about
the lower part of the face and muzzle. The nerves,
however, are wisely and beautifully interwoven, for the
lips, being the seat of touch, require all the flexibility
and more than the sensibility of the human land.
“The inferior maxillary nerve, or third branch of
the trigeminus, emerges from the cranium through
the foramen lacerum basis cranii, and very soon gives
off four important branches. The first branch, reck-
oning posteriorly, proceeds backward below the con-
dyle of the jaw, where it divides into two portions.
The first runs up to the parotid gland, ramifies into
many filaments, and unites with the seventh pair. It
dips deep into and principally supplies the temporal
muscle, and penetrates and is distributed through the
masseter muscle. In this division there seems to be
concentrated the greater part of the motor fibrils of
the trigeminus, for these are muscles of extensive and
powerful action. There are few muscles of the frame
that are oftener or more powerfully employed than
those concerned in mastication; but with the motor
fibrils those of sensation are doubtless conjoined.
“The second branch is a long and slender one. It
first dips into the pterygoideus muscle, which is sup-
plied by it; consequently it is here also a motor as well
as a sensitive nerve. It then passes around or behind
the tuberosity of the upper jaw, supplying the bucci-
nator muscle—possibly with sensitive fibrils alone, for

224 THE FIFTH PAIR OF NERVES.

others go to this muscle from the seventh pair. In
the buccinator these fibrils are usually lost; but some-
times a few of them may be traced to the lower lip.

“The third branch, in the order of its being given
off, is the dental nerve. This is generally considered
the continuation of the trunk of the inferior maxillary
nerve. It passes across the pterygoideus and enters a
canal (the dental canal), on the inner face of the lower
jawbone, near the upper edge, and at the bending or
angle of the jaw. It takes its course along the interior
of the bone (the canal), close to the roots of the teeth,
and sends out filaments to each of them. Emerging
through the lower maxillary foramen, it divides into
two branches, one of which is distributed in numerous
ramifications on the outside of the lower lip, and the
other in fewer ramifications on the inside. These are
evidently sensitive fibrils, the power of motion being
derived from the seventh pair of nerves.

“The fourth branch in point of order, but which
does not enter the ‘dental canal,’ is the gustatory or
lingual nerve, the largest of the four. It is singularly
flat, like a little ribbon. It runs along the inside of
the lower jaw, and a branch of it enters a foramen in
the jaw to supply the roots of the incisor teeth; but
the main nerve, proceeding obliquely downward, gives
fibrils to the submaxillary glands, and to the glands
and muscles at the base of the mouth generally. These
fibrils form true plexuses about the salivary glands and
the muscles of the tongue. ‘They anastomose freely
with the twelfth pair (the linguales or motor nerve of
the tongue), as the twelfth had already done with the
seventh (the ‘portio dura’). The gustatory branch
penetrates the substance of the tongue between the
stylo and genio-glossal muscles, passing obliquely to

RICH PLEXUSES AND LOOPED FILAMENTS. 225

the surface of the tongue, and terminating in the pa-
pille. The papille, thus endowed with nervous influ-
ence, are the seat of the sense of taste.”

Of the fifth nerve (in man and in the horse) Prof.
Owen (quoting partly from Dr. Swan), says (“Odon-
tography,” vol. i, pp. lxv—vi):

“lhe nerves of the teeth are derived from the tri-
geminal, or fifth pair, of which the second division sup-
plies those of the upper jaw, the third division those
of the lower. In the human subject, the three dental
branches of the infra-orbital nerve intercommunicate
by their primary branches, from which, and from a
rich plexus formed by secondary branches upon the
membrane lining the antrum, two sets of nerves are
sent off to the alveolar processes of the upper jaw; one
set (rami dentales) supplies the teeth, the other (rami
gingivales) the osseous tissue of the gums. The latter
agree in number with the intervals of the teeth, as the
proper dental nerves do with the teeth themselves.
These two sets are not, however, so distinct but that
some intercommunications are established between the
fine branches sent off in their progress to the parts
they are specially destined to supply. The rami den-
tales take the more direct course (through the middle
part of the osseous tissue to the teeth) penetrate the
orifices of the fangs, and form a rich plexus with .
rhomboidal meshes upon the coronal surface of the .
pulp, the peripheral elementary filaments returning
into the plexus by loops. In the lower jaw the dental
nerve, besides supplying the proper nerves to the teeth,
also forms a rich plexus, in which it is joined by some
branches from the division of the nerve that afterward
escapes by the foramen mentale, and from this plexus

226 THE FIFTH PAIR OF NERVES.

the cancellous tissue of the bone and the vascular
gums are supplied. + + ** *

“In the horse the maxillary plexus is most devel-
oped above and between the alveoli of the three pre-
molar teeth. It is less complex where it supplies the
molar teeth, their alveoli, and the gums. In the
lower jaw of the horse a very rich plexus begins to be
formed in the cancellous substance of the bone by
branches of the dental nerve, soon after its entry into
the canal.”

VOCABULARY;

Note.—The definitions, where not otherwise credited, are
from ‘‘ Dunglison’s Medical Dictionary.”

A.

ALA (plural, ale). Projections from the median line; as the
alz nasi, ale of the uterus, &e.

ALBUMEN. An important organic compound. The character-
istic ingredient in the white of egg ; abounds in the serum
of the blood, in chyle, lymph, skin, muscles, brain, and the
juice of flesh; in small quantity in most vegetable juices,
and in Bright’s disease in considerable quantity in the urine.
It is the foundation, says Liebig, of the whole series of pecu-
liar tissues which constitute those organs which are the
seat of all vital actions. C. F. Chandler.

ALVE’OLAR ARCHES are formed by the margins or borders of
the two jaws, which are hollowed by the aiveoli.

ALVEOLAR ARTERY, arises from the internal maxillary, de-
scends behind the tuberosity of the upper jaw, and gives
branches to the upper molar teeth, gums, periosteum, mem-
brane of the maxillary sinus, and buccinator muscle.

ALVEOLAR BORDER. The part of the jaws that is hollowed by
the alveoli.

ALVEOLAR MEMBRANES are very fine membranes, situated be-
tween the teeth and alveoli, and formed by a portion of the
sac which incloses the tooth before it pierces the gum. By
some this membrane has been called the ‘alveolo-dental
periosteum,’

ALVEOLAR VEIN. This has a distribution similar to the artery,

228 VOCABULARY.

ALVE’OLUS (pl. alveoli). The alveoli are the sockets of the
teeth, into which they are, as it were, driven. Their size
and shape are determined by the teeth which they receive,
and they are pierced at the apex by small holes which give
passage to the dental vessels and nerves, .

ANASTOMO’SiIS (‘a mouth’). Communication between two ves-
sels. By considering the nerves to be channels, in which a
nervous fluid circulates, their communication likewise has
been called anastomesis. By means of anastomoses, if the
course of a fluid be arrested in one vessel, it can proceed
along others.

ANISODAC’TYLE. Hoofed quadrupeds with toes (on the hind-
feet at least) in uneven numbers, as one, three, or five, the
latter being manifested by the Proboscidians. All these have
a simple stomach and an enormous cecum. Examples:
Horse, tapir, rhinoceros, elephant. R. Owen.

ANTE’RIOR (ante ‘before’). Great confusion has prevailed with
anatomists in the use of the terms before, behind, &c.

(A practical definition of anterior appears to be {1) parts
in front, supposing the body to be equally divided longi-
tudinally from right to left ; (2) parts nearest the operator,
parts beyond being posterior.)

ANTRUM. A cavern. A name given to certain cavities in
bones, the entrance to which is smaller than the bottom.
ANTRUM OF HiGHMORE. A deep cavity in the substance of the
superior maxillary bone, communicating with the middle
meatus of the nose. It is lined by a prolongation of the

Schneiderian membrane.

ARACH’NOID MEMBRANE. A name given to several mem-
branes, which, by their extreme thinness, resemble spider-
webs. The moderns use it for one of the membranes of the
brain, situate between the dura mater and pia mater. Itisa
serous membrane, composed of two layers, the external being
confounded, in the greater part of its extent, with the dura
mater, and, like it, lining the interior of the cranium and spi-
nal canal; the other is extended over the brain, from which
it is separated by the pia mater, without passing into the
sinuosities between the convolutions, and penetrating into
the interior of the brain by an opening at its posterior part,
under the ‘corpus callosum.’ It formsa part of the investing

AN ARMED QUADRUPCD. 229

sheath of nerves, as they pass from the encephalie cavities.
Its chief uses seem to be to envelop and, in some measure,
protect the brain, and to secrete a fluid for the purpose of
keeping it in a state best adapted for the performance of its
functions.

AREOLA. A diminutive of ‘area.’ Anatomists understand by
areole the interstices between the fibers composing organs,
or those existing between laminz, or between vessels which
interlace with each other. :

ARGEN’TI NiTRAS. Nitrate of silver; lunar caustic. The vir-
tues of nitrate of silver are tonic and escharotic. It is given
in chorea, epilepsy, &c.; locally, it is used in various cases as
an escharotic. Dose, gr. 1-8 to gr. 1-4, in pill, three times
a day.

ARMADILLO. (So called from being protected or armed by a
scaly covering like the plate armor of the middle ages.) A
genusof South American quadrupeds, belonging to the order
of edentata, and characterized by a defensive armor of small
bony plates, covering the head and trunk, and sometimes the
tail. Brande.

ARTICULA’TION. The union of bones with each other, as well
as the kind of union. Articulations are generally divided
into two kinds—movable and immovable. The articulations
are subject to a number of diseases, which are generally some-
what severe; they may be physical, as wounds, sprains, lux-
ations, &c., or they may be organic, as ankylosis, extraneous
bodies, caries, rheumatism, gout, Xe.

AT’RopHY. Progressive and morbid diminution in the bulk of
the whole body or ofa part. Atrophy is generally symp-
tomatic. Any tissue or organ thus affected is said to be
‘atrophied.’

AURIC’ULAR. (The ear.) That which belongs to the ear, espe-
cially the external ear.

B.

BatTrRa’cutaA. An order of reptiles including toads, frogs, and
salamanders. Brande.
One of the five great classes into which vertebrate animals

are usuallydivided, though some writers have reduced the
class to the rank of an order of reptiles, a class with which

230 VOCABULARY.

they are popularly confounded. The batrachians are cold-
blooded and oviparous, and in most living species are with-
out scales, and the blood is partly aérated through the skin.
The young, for the mest part, breathe by gills like those of
fishes; they assume a fish-like form (as the tadpole), and
finally, when adult, with few exceptions, lose their gills and
breathe by lungs, like true or scaly reptiles. They generally
have limbs, but not always. Johnsons N. UT. Cye.

Bi’FuRCATION. (A fork.) Division of a trunk into two
branches, as the bifurcation of the trachea, aorta, &c.

Buccau. That which concerns the mouth, and especially the
cheek,

Cc.

CzcuM. The blind gut; so called from its being perforated at
one end only. That portion of the intestinal canal which is
seated between the termination of the ileum and beginning
of the colon, and which fijls, almost wholly, the right iliac
fossa, where the peritoneum retains ifimmovably. Its length
is about three or four fingers’ breadth. The ileo-cxcal valve,
or valve of Bauhin, shuts off all communication between it
and the ileum, and the ‘ Appendix vermiformis ceci’ is at-
tached to it.

In the horse the cecum (water stomach) will hold four gal-
lons. A horse will drink at one time a great deal more than
his stomach will contain; but even if he drinks a less quan-
tity, it remains, not in the stomach or small intestines, but
passes to the cecum, and is there retained, as in a reservoir,
to supply the wants of the system. Youatt.

CaL’cuLus. A diminutive of ‘caix,’ a lime-stone. Calculi are
concretions, which may form in every part of the animal
body, but are most frequently found in the organs that act
as reservoirs, and in the excretory canals. They are met
with in the tonsils, joints, biliary ducts, digestive passages,
lachryma! ducts, mamme, pancreas, pineal giand, prostate,
lungs, salivary, spermatic, and urinary passages, and in the
uterus, The causes which give rise to them are obscure,
Those that occur in reservoirs or ducts are supposed to be
owing to the deposition of the substances, which compose
them, from the fluid as it passes along the duct ; those which
occur in the substance of an organ are regarded as the pro-

THE USES OF BONE CELLS. 231

duct of some chronic irritation. Their general effect is to
irritate, as extraneous bodies, the parts with which they are
in contact, and to produce retention of the fluid whence they
have been formed. The symptoms differ, according to the
sensibility of the organ and the importance of the particular
secretion whose discharge they impede. Their ‘solution’ is
generally impracticabie. Spontaneous expulsion or extrac-
tion is the only way of getting rid of them.

CANCEL’LI. ‘Lattice-work.’ The cellular cr spongy texture of
bone, consisting of numerous cells, communicating with each
other. They contain a fatty matter, analogous to marrow.
This texture is met with principally at the extremities of
long bones, and some of the short bones consist almost wholly
of it. It allows of the expansion of the extremities of bones,
without adding to their weight, and deadens concussions.

CaAN’utA. Diminutive of canna, ‘a reed.’ A small tube of gold,
silver, platinum, iron, lead, wood, elastic gum, or gutta-
percha, used for various purposes in surgery.

CAPILLARY (from capiilus,‘s hair’). Hair-like; small.

CAPILLARY VESSELS are the extreme radicles of the arteries
and veins, which together constitute the capillary, interme-
diate, or peripheral vascular system—~the methe’mata blood
channels of Dr. Marshall Hall (that is, the system of vessels
in which the blood undergoes the change from venous to
arterial, and conversely). They possess an action distinct
from that of the heart.

Ca’R1es. (Rottenness.) A disease of bones analogous to ulcer-
ation of soft tissues; a term for open ulcer of bone and
chronic ostitis of its connective tissue, with solution of the
earthy part. It begins as an inflammation, accompanied by
periostitis, followed by exudation of new materials and
softening. Sometimes the bone-cells are filled with a red-
dish fluid, and there are masses of tubercle. After caries
has existed for some time the abscess bursts; aperture re-
mains open, discharging a fluid and particles of bone; a
probe is felt to sink into a soft, gritty substance—carious
bone. Caries is molecular death of bone; necrosis is death
of a mass of bone. Willard Parker.

CAROT IDs. The great arteries of the neck, which carry blood
to the head.

252 VOCABULARY.

Canr’TILAGE. A solid part of the animal body, of a consistence
between bone and ligament, which in the fetus is a substi-
tute for bone, but in the adult exists oniy in the joints, at
the extremities of the ribs, Xe.

CER’vicAL. Jiverything which concerns the neck, especially
the back part.

CHEVROTAIN’. A species of the genus Moschus, related to the
deer, but having no horns, and otherwise peculiar. It is
small, light, and graceful, and lives in the mountains of Asia,
from the Altai to Java. Dana.

CHORCID MEMBRANE. A thin membrane, of a very dark color,
which lines the sclerotic internally. It is situate between the
sclerotic and retina, has an opening posteriorly for the pas-
sage of the optic nerve, and terminates anteriorly at the great
circumference of the iris, where it is continuous with the cili-
ary processes. The internal surface is covered with a dark
pigment, consisting of several layers of pigment cells. Its
use seems to be to absorb the rays of light after they have
traversed the retina.

Civ’/tARY. Relating to the eyelashes, or to cilia. This epithet
has also been applied to different parts, which enter into the
structure of the eye, from the resemblance between some of
them (the ciliary processes) and the eyelashes.

Coton. That portion of the large intestines which extends
from the cecum to the rectuni, The colon is usually divided
into four portions. 1. The right lumbar or ascending colon,
situate in the right lumbar region, and beginning at the
cecum. 2. The transverse colon—transverse arch of the
colon—the portion which crosses from the right to the left
side, at the upper part of the abdomen. 3. The left lumbar
or descending colon, extending from the left part of the trans-
verse arch, opposite the outer portion of the left kidney, to
the corresponding iliac fossa. 4. The iliac colon, or sigmoid
flexure of the colon; the portion which makes a double cur-
vature in the left iliac fossa, and ends in the rectum.

In the horse the colon is exceedingly large, and is capable
of containing no less than twelve gallons of liquid or pulpy
food. It is of considerable length ; completely traversing the
diameter of the abdominal cavity, it is then reflected upon
itself, and retraverses the same space. Youatt.

THE USES OF COMPARATIVE ANATOMY. 233

Com’MissurRES. The point of union between two parts; thus
the commissures of tie eyelids, lips, Xe., are the angles which
they form at the place of union.

COMPARATIVE ANATOMY, The science which treats of the
structure and relation of organs in the various branches of
the animal kingdom, without a knowledge of which it is im-
possible to understand the beautifully progressive develop-
ment of organization, necessary even for the full comprehen-
sion of the uses of many parts of the human body, which,
apparently rudimentary and useless in man, are highly de-
veloped in other animals. This science is also the basis of
physiology and the natural classification of animals.

American Cyclopedia.

Con’DYLE. An articular eminence, round in one direction, flat
in the other. A kind of process, met with more particularly
in the ginglymoid joints, such as the condyles of the occipi-
tal, inferior maxillary bone, &c.

CONGEN’ITAL (from con and genitus, ‘begotten’). Diseases
which infants have at birth; hence, congenital affections are

hose that depend on faulty conformation, as congenital her-
nia, congenital cataract, &.

CoNJUNCTI’'VA MEMBRA’NA. A mucous membrane, so called
hecause it unttes the globe of the eye with the eyelids. It
covers the anterior surface of the eye, the inner surface of the
eyelids, and the ‘caruncula Jacnrymalis.’ It possesses great
general sensibility, communicated to it by the fifth pair of
nerves.

CopyBA’RA is the largest known quadruped of the order Ro-
dentia, and belongs to the family Cavide. It is an aquatic
animal, a native of South America, and feeds on vegetable
food exclusively. Its dentition resembles that of the cavy,
except that the grinding teeth are formed of many trans-
verse plates, the number of plates increasing as the animal
advances in age. It is inoffensive and easily tamed. The
flesh is esteemed good food. It is somewhat smaller than
the common hog. Johnson’s New Universal Cyelopedia.

Cor’PuscLe. One of the ultimate morphological elements of the
body. They exist at some time or other in all the tissues of
the body, ggverning their vital actions. The white and red
corpuscles of the blood, epithelial bodies and ganglionic nerve

234 VOCABULARY.

cells areexamples. They are mainly composed of protoplasm
and contain in their interior bodies called nuclei, in which
are still smaller ones called nucleoli. LT. E. Satterthwaite.
CORRELA’TION (mutual relation) oF FoRcEsS (otherwise called
‘Transmutation of Force or Energy’). A phrase of recent
origin, employed to express the theory that any one of the
various forms of physical force may be converted into one or
more of the other forms. The cardinal point in this theory
is the doctrine of heat and its relation to other agents, espe-
cially to mechanical moticn. For example, the heat mani-
fested when we rub two flat surfaces briskly against each
other, is only our own muscular motion checked by the fric-
tion, and changed thereby into the heat which the surfaces
reveal. On the other hand, this muscular motion is only the
heat of our bodily frame expending itself in this way. In
either case the energy has not been annihilated, but only
transferred, and appears in a new form.
Johnson's N. U. Cyc., article revised by J. H. Seelye.
CruRA. The plural of crus, ‘aleg.’ Applied to some parts of
the body, from their resemblance to legs or roots, as the
‘crura cerebri,’ ‘crura cerebelli,’ &c.
CUL-DE-SAC. Any bag-shaped cavity, tubular vessel, or organ,
open only at one end. Dana.

D.

DENTAL CANAL. The bony canals through which the vessels
and nerves pass to the interior of the teeth.

DENTAL Cavity. A cavity in the interior of the teeth, in which
is situate the dental pulp. (More properly the pulpal cavity.)

DENTAL PuLp. The pultaceous substance, of a reddish-gray
color, very soft and sensible, which fills the cavity of the
teeth. It is well supplied with capillary vessels.

DENTIG’EROUS. Tooth-carrying, as dentigerous cysts; one
containing teeth.-

DERMAL. Relating or belonging to the skin.

DERMATOID or DERMOID. That which is similar to the skin.
This name is given to different tissues which resemble the
skin. The dura mater has been so called by some.

DETER’GENTS. Medicines which possess the power to deterge
or cleanse parts, as wounds, ulcers, &c.

THE USE OF A DIVERTICULUM. 235

DIABE’TES. A disease characterized by great augmentation and
often manifest alteration in the secretion of urine, with ex-
cessive thirst and progressive emaciation. The quantity of
urine discharged in 24 hours is sometimes 30 pints and up-
ward, each pint containing 2} ounces saccharine matter.

Di’aporaGeMm. 1. A dividing membrane or thin partition, com-
monly with an opening through it. 2. The muscle separa-
ting the chest or thorax from the abdomen or lower belly ;
the midriff. Webster.

DIATH’ESIS. Disposition, constitution, affection of the body ;
predisposition to certain diseases rather than to others. The
principal diatheses are the cancerous, scrofulous, scorbutic
(pertaining to scurvy), rheumatic, gouty, and calculous.

DIveERTIC’uLUM. A blind tube branching out from the course
of a larger one. An organ which is capable of receiving an
unusual quantity of blood, when the circulation is obstructed
or modified elsewhere, is said to act as a diverticulum.

In the marsupials only four teeth (one in each jaw on each
side) are deciduous. The permanent set are developed from
diverticula of the sacs which originated the first set. Gill.

Duaone’. A herbivorous, cetaceous animal with a tapering body
ending in a crescent-shaped fin. The fabled mermaid seems
to have been founded on the dugong. Gilbert. Brande.

It is generally from 8 to 12 feet long, thongh it is said to
sometimes attain the length of 25 feet. The upper lip is
thick and fleshy and forms a kind of snout; the upper jaw
bends downward almost toa right angle ; eyes small, witha
nictitating membrane; the skin is thick and smooth. Its
flesh is said to resemble beef, and is prized as food. The oil
is recommended as a substitute for cod-liver oil. J.’s Cyc.

DurA MATHER. (Hard.) The outermost of three membranes
enveloping the brain and spinal cord. Within the skull
it so completely joins the bones that it may be regarded
as their endosteum. Within the spinal canal it becomes
a fibrous tube, separated from the vertebrae (which have
no endosteum) by a loose, areolar, fatty tissue and a plexus
of veins. It sends out sheaths for the nerves as they go
through their foramina. It is usually studded, except in
infancy, by minute whitish masses (Paccionian bodies) whose
use is not known, Its inner surface is covered with pave-

236 VOCABULARY.

ment epithelium, and perhaps by the parietal layer of the
arachnoid membrane, Lhd.

EK.

Econ’omy. By the term ‘animal economy’ is understood the
aggregate of the laws which govern the organism. The word
economy is also used for the aggregate of paris which con-
stitute man or animals.

EprentTa’TA. In natural history, an order of animals that are
destitute of front teeth, as the armadillo and ant-eater. Bell.

EDEN’ TULUS. One without teeth.

Em’sBRyo. The fecundated germ, in the early stages of its de-
velopment in utero. Ata certain period of its increase, the
name ‘fetus’ is given to it, but at what period is not deter-
mined. Generally, the embryo state is considered to extend
to the periol of quickening.

ENCEPHALITIS. This term has been used by some nosologists
(classifiers of diseases) synonymously with ‘cephalitis’ and
‘phrenitis.’ By others it has been appropriated to inflam-
mation of the brain, in contradistinction to that of the mem-
branes.

E’ocENE. In geology, a term applied to the earlier tertiary de-
posits, in which are a few organic remains of existing species
of animals. Hence the term eocene (recent), which denotes
the dawn of the existing state of things. -

Dana. Lyell. Mantel.

In America the eocene strata contain numerous fossils,
mostly marine mollusks, but also include some gigantic ver-
tebrates, a carnivorous cetacean seventy feet in length, and a
shark of which the teeth are sometimes six inches in length.
The Wyoming beds have furnished the remains of a remark-
able group of mammals, which are thought by Prof. Marsh
to form a new order, and which he has named ‘ Dinocerata.’
The largest of these (Dinoceras mirabilis) had the bulk of an
elephant, and was provided with three pairs of horns and a
pair of great saber-like canine teeth. Johnson’s N. U. Cye.

EPIDER’Mis. A modification of the epithelium, molded to tle
papillary layer of the true skin ; composed of agglutinated,
flattened cells, which are dovalobad in the liquor sanguinis,
the latter being poured out on the true skin’s external sur-
face. In the deeper layers the cells are rounded or columnar,

THE UNIVERSE A SERIES OF CHANGES, 237

containing in most races of men more or less pigmentary
matter, which gives the skin its various shades from black
to white. It is penetrated by the ducts of the skin’s sweat-
glands and oil-glands; becomes hard in palms of hands;
otherwise is soft. The hair and nails are modifications of it.
On leaves it is penetrated by the stomata, transmitting
exhalations and absorbing carbonic acid, the most important
part of plant food. Ibid.
EPITHE’LIuM. (Soft, delicate, tender.) The layer of cells lin-
ing serous (closed) and mucous (open) cavities, the mucous
epithelium being continuous with tle epidermis. (Mucous
is formed by the bursting of epithelial cells.) Ibid.
EsopnH’acus. The gullet. Extends from pharynx to stomach.
Erumor. Sieve-like. The ethmoid bone is one of the eight
bones which compose the cranium, so called because its up-
per plate is pierced by numerous holes. It is situate at the
anterior, inferior, and middle part of the cranium.
Evouvu’Tion. According to the hypothesis of evolution, in its
simplest form, the universe as it now exists is the result of
“an immense series of changes,” related to and dependent
upon each other, as successive steps, or rather growths, con-
stituting a progress ; analogous to the unfolding or evolving
of the parts of a living organism. Evolution is defined by
Herbert Spencer as consisting in a progress from the homo-
geneous to the heterogencous, from general to special, from
the simple to the complex ; and this process is considered to
be traceable in the formation of the worlds in space, in the
multiplication of the types and species of plants and animals
on the globe, in the origination and diversity of languages,
literature, arts, and sciences, and in all the changes of human
institutions and society. Henry Harishorne.
The animal kingdom displays a unity of plan or a corrcla-
tion of parts by which common princinles are traced through
the most disguising diversities of form, so that in aspect, struc-
ture, and functions the various tribes of animals pass into
each other by slight and gradual transitions. The arm ofa
man, the fore limb of a quadruned, the wing of a bird, and
the fin of a fish are homologous. that is, they contain the
same essential parts, modified in correspondence with the dif-
ferent circumstances of the animal; and so with the other

298 VOCABULARY.

organs. Prof. Cope says: “Every individual of every species
of a given branch of the animal kingdom is composed of ele-
menis common to all, and the diifereuces which are so radi-
cal in the higher grades are but the modifications of the same
elemental] parts,” EH. L. Youmans.

EXFOLIATION (from ex and foliwm, ‘a leaf’). By this is meant
the separation of the dead portions of a bone, tendon, apon-
eurosis (a white suining membrane), or cartilage, under the
form of lameliz (small seales). Exfoliation is accomplished
by the instinctive action of the parts, and its object is to de-
tach the dead portions from those subjacent, which are still
alive. For this purpose the latter throw out fleshy granula-
tions, and a more or less abundant suppuration occurs, which
tends to separate the exfoliated part—now become an extra-
neous body.

Exosto’sis. An osseous tumor, which forms at the surface of
bones, or in their cavities.

Exostosis DENTIUM. LExostosis of the teeth.

F.

FERRU’GINOUS (chalyb’eate). Of or belonging to iron ; contain-
ing iron. Any medicine into which iron enters, as chalyb-
eate mixture, pills, waters, &.

Fw’tus. See‘ embryo.’

Fiser. An organic filament, of a solid consistence, and more or
less extensible, which enters into the composition of every
animal and vegetable texture.

Fir/amMpnt. A thread. This word is used synonymously with
fibril ; thus we say a nervous or cellular filament or fibril.
Fis’‘runa. ‘A pipeorreed.’ A solution of continuity (a division

of parts previously continuous) of greater or less depth and
sinuosity, the opening of which is narrow, and the disease
kept up by an altered texture of parts, so that it is not dis-
posed to heal. A fistula is ‘incomplete’ or ° blind’ when it
and ‘complete’ when there are two, the

has but one opening,
the other exter-

one communieatine with an internal cavity,
nally. It is lined in its whole course by a membrane which
seems analogous to mucous membranes.

Fou’Licun. A follicle or crypt is a small, roundish, hollow
body, situate in the substance of the skin or mucous mem-
branes, and constantly pouring the fluid which it secretes on

USES OF GASTRIC JUICE. 239

their surfaces. The use of the secretion is to keep the parts
on which it is poured supple and moist, and to preserve them
from the action of irritating bodies with which they have to
come in contact. —

Fora’MEN. Any cavity pierced through and through, Also
the orifice to a canal. sab

Fossa. <A cavity of greater or less depth, the entrance to which
is always larger than the base.

FraNuUM. A small bridle. A name given to several membran-
ous folds, which bridle and retain certain organs.

FRONTAL Bong. A double bone in the fetus, single in the adult,
situate at the base of the cranium, aud at the superior part
of the face.

Fone T1on. The action of an organ or system of organs. Any
act necessary for accomplishing a vital phenomenon. A
function is a special office in the animal economy, which has
as its instrument an organ or apparatus of organs.

Funevus.. The mushroom order of plants. In pathology the
word is commonly used synonymoasly with fungosity (my-
eosis).

Funeus HaMAto’DEs (Hematodes Fungus). An exceedingly
alarming carcinomatous (cancerous) affection, which was first
described with accuracy by Mr. John Burns, of Glasgow. It
consists in the development of cancerous tumors, in which
the inflammation is accompanied with violent heat and pain,
and with fungus aud bleeding excrescences.

G.

GANG’LION. Nervous ganglions are enlargements or knots in
the course of a nerve.

GAsTRic. Belonging or relating to the stomach.

Gastric Juice. A fluid secreted from the mucous membrane
of the stomach. It assists digestion.

GENTIAN WINE (vinum gentiane compositum, or wine bitters).
‘Gentiana Lutea’ is the systematic name of the officinal
gentian. The plant is common in the mountains of Europe.
The root is almost inodorous, extremely bitter, and yields
its virtues to ether, alcohol, and water. It is tonic and
stomachic, and, in large doses, aperient. It is most fre-
quently, however, used in infusion or tincture.

240 VOCABULARY.

GEOLOGY is that branch of natural science which treats of the
siructure of the crust of the earth and the mode of formation
of its rocks, together with the history of physical changes
and of life on our planet during the successive stages of its
history. It has been inferred that its actual crust must be

ery thick, perhaps not less than 2,500 miles. Geology de-
pends upon mineralogy for its knowledge of the constituents
of rocks, and upon chemistry and physics fcr its knowledge
of the laws of change; and in its study of fossil remains it is
closely connected with the sciences of zodlogy and botany.
A knowledge of geology lies at the base of physical geogra-
phy, and is essential to the skillful prosecution of mining
and other useful arts. J. W. Dawson.
The facts proved by geology are that during an immense
but unknown period the surface of the earth bas undergone
successive changes; land lias sunk beneath the ccean, while
fresh land has risen up from it ; mountain chains have been
elevaied ; islands have been formed into continents, and con-
tinents submerged till they have become islands; and these
changes have taken place, not once merely, but perhaps
hundreds, perhaps thousands of times. A, L. Wallace.
Prof. Dana says the ‘earth was first a featureless globe of
fire ; then had its oceans and dry land; in course of time re-
ceived mountains and rivers, and finally all those diversities
of surface which now characterize it.”

GuAND. (An acorn; a kernel.) Softish, granular, lobated or-
gans, composed of vessels and a particular texture, which
draw from the blocd the moiecules necessary for the forma-
tion of new fiuids, conveying them externally by means of
one or more excretory ducts. Each gland has an organiza-
tion peculiar to it, but we know not the intimate nature of
the glandular texture.

Guana’co, The ‘ Auchenia Huanzca,’ a species of the genus of
ruminant mammals to which the llama belongs. It inhabits
the Andes, and is domesticated. It is allied to the camel.

Webster.

The guanaco is especially abundant in Patagonia and
Chili, where it forms large flocks. It is about three feet high
at the shoulders, and is extremely swift. In domestication it
is ill-tempered, and has a disagreeable habit of ejecting saliva

HISTOLOGY—HUMAN, COMPARATIVE, ETC. 241

upon unwelcome visitors. In its wild state it seldom drinks
water. Its flesh is edible and its skin valuable.
Johnson's N. U. Cye.
H.

HAVERSIAN CANALS. (Canals of Havers, nutritive canals, &c.)
The canals through which the vessels pass to the bones.
They are lined by a very fine lamina of compact texture, or
are formed in the texture itself. There is generally one large
nutritious canal in a Jong bone, situate toward its middle.

Hia’tus. A foramen or aperture. Mouth. The vulva. Also
yawning.

HistTou’oGy is the branch of anatomy which treats of the minute
structure of the tisswes of which living beings are composed.
It is divided into ‘ human histology,’ which treats of the tis-
sues of man ; ‘comparative histology,’ which treats of the tis-
sues of the lower animals, and ‘ vegetable histology,’ which
treats of the tissues of plants. Each of these divisions may
be subdivided into ‘normal’ and ‘pathological’ histology,
the first referring to the healthy tissues, the second investi-
gating the changes they undergo in disease. J. J. Woodward.

Hoove. A disease in cattle, consisting in the excessive inflation
of the stomach by gas, ordinarily caused by eating too much
green food. Gardner.

HYPER’TROPHY. The state of a part in which the nutrition is
performed with greater activity, and which on that account
at length acquires unusual bulk. The part thus affected is
said to be hypertrophied or hypertrophous.

I.

INFILTRA’TION. To filter; effusion. The accumulation of a
fluid in the areole of a texture, and particularly in the areo-
lar membrane. The fluid effused is ordinarily the ‘liquor
sanguinis,’ sound or altered; sometimes blood or pus, feeces
or urine. When infiltration of a serous fluid is general, it
constitutes ‘anasarca’ (dropsy); when local, ‘ cedema.’

INTERSTITIAL. Applied to that which occurs in the interstices
of an organ, as interstitial absorption, interstitial pregnancy,
&c. (See ‘Suppuration.’)

INTRA-UTERINE. © (Intra, ‘within,’ uterus, ‘the womb.’) That
which takes place within the womb, as intra-uterine life.

11

242 VOCABULARY.

Irnts. So called from its resembling the rainbow in a variety of
colors. A membrane, stretched vertically at the anterior
part of the eye, in the midst of the aqueous humor, in which
it forms a kind of circular, flat partition, separating the an-
terior from the posterior chamber. It is perforated by a cir-
cular opening called the pupil, which is constantly varying
its dimensions, owing to the contractions of the fibers of the
iris.

IsopAc’ryLE. Hoofed quadrupeds with toes in even number, as
two or four, and which have a more or less complicated
stomach, with a moderate-sized, simple cecum. Examples:
Ox, hog, peccary, hippopotamus. Lf. Owen.

L.

LACH’RYMAL. Belonging to the tears. This epithet is given
to various parts.

LACUN# OF BonE. Certain dark, stellate spots, with thread-
like lines raliating from them, seen under a high magnifying
power. These were first believed to be solid csseous cor-
puscles or cells (corpuscles of Purkinjé), but are now re-
garded as excavations in the bone, with minute tubes or
canaliculi proceeding from them and communicating with
the Haversian canals. The lacune and canaliculi are fibers
concentrated in the transit of nutrient fluid through the osse-
ous tissue.

Lam’inaA. ‘A thin, flat part of a bone; a plate or table, as the
cribriform lamina or plate of the ethmoid bone. Lamina and
lamella are generally used synonymously, although the latter
is properly a diminutive of the former.

Les1o 1. Derangement, disorder; any morbid change, either in
the exercise of functions or in the texture of organs. ‘Or-
ganic lesion’ is synonymous with organic disease,

Lipo’MA. A fatty tumor of an encysted or other character.

Lirom’atTous. Having the nature of lipoma, as a lipomatous
mass.

Liquor SANne’uInis. A term given by Dr. B. Babington to one
of the constituents of the blood, the other being the red par-
ticles. It is the effused material (called plesma, coagulable
or plastic lymph, intercellular fluid, &c.), from which the cells
obtain the constituents of the different tissues and secretions.

MOLARS WiTH CONE-LIKE PROJECTIONS. 243

M.

MALAR. Beionging to the cheek, as the malar bone.

MALAR PRrocEss. Zygomatic process. (Cheek bone process.)

MASSETER. A muscle situate at the posterior part of the cheek,
and lying upon the ramus of tie lower jawbone, _ Its office is
to raise the lower jaw and to act in mastication.

Mas’ToDON. An extinct genus of quadrupeds. When alive it
must have been twelve or thirteen feet high, and, including
the tusks, about twenty-five feet long. The tusks measure
ten feet eleven inches, about two and a half feet being im-
planted in the socket. According to Owen, the teeth are
seven on each side, above and below. The molars have
wedge-shaped, transverse ridges, the summits of which are
divided by a depression lengthwise with the tooth, and sub-
divided into cones, more or less resembling the teats of a cow.
In some species there are from three to five ridges to each
posterior molar; in other species five or more. O. C0. Marsh.

(The mastodon takes its name from the mastoid or nipple-

like processes of its teeth.)

Mastoip. Having the form of a nipple.

Max’tnuary. Relating or belonging to the jaws.

MeEa’TUs. A passage or canal.

MEDIAN Ling. A vertical line, supposed to divide a body lon-
gitudinaily into two equal parts, the one right, the other left.

MED’ULLARY. Relating to the marrow, or analogous to marrow,

MEGATHE’RIUM. An extinct genus of Quaternary mammals.
‘Megatherium Cuvieri, from South America, exceeded the
rhinoceros in size, its skeleton measuring eighteen feet in
length. The vertebre of the tail are very large and power-
ful, and that organ, with the hind-legs, seems to have formed
a support for the heavy body, while the huge fore-legs were
employed in breaking the branches from trees or tearing
them down for food. There are four toes in front and two
behind. The teeth, five above and four below on each side,
resemble those of the sloths. They grew from persistent
pulps, and are deeply implanted in the jaws; they have a
grinding surface of triangular ridges, and were fitted for mas-
ticating coarse vegetable food. O. C. Marsh.

MEMBRANE. A name given to different thin organs, represent-

244 VOCABULARY.

’ ing a species of supple and more or less elastic webs, varying
in their structure and vital properties, and intended, in gen-
eral, to absorb or secrete certain fluids, and to separate, en-
velop, and form other organs. Bichat has divided the mem-
branes into simple and compound.

MeEmMBRA’NA Nic’TITANS. The ‘haw’ of the horse’s eye. It is
a triangular-shaped cartilage, concealed within the inner cor-
ner of the eye, and is black or pied. It is used by the horse,
in lieu of hands, to wipe away dust, insects, &c. The eye
of the horse has strong muscles attached to it, and one,
peculiar to quadripeds, by the aid of which the eye may be
drawn back out of the reach of danger. When this muscle
acts, the haw, which is guided by the eyelids, shoots across
the eye with the rapidity of lightning, and thus carries off
the offending matter. Its return is equally rapid. Youatt.

(Prof. Youatt denounces the practice of cutting out the
haw as barbarous, that is, in ordinary cases of inflammation.
He says that if farriers and grooms were compelled to walk
for miles in the dust without being permitted to wipe or
cleanse their eyes, they would feel the torture to which they
often subject the horse.)

Mr’ocENE. Literally, less recent. In geology, a term applied
to the middle division of the tertiary strata, containing fewer
shells of recent species than the Pliocene, but more than the
Eocene. Lyell.

The Miccene is apparently the culminating age of the
mammalia, s> far as physical development is concerned,
which accords with its remarkably genial climate and exu-
berant vegetation. In Europe the beds of this age present
for the first time examples of the monkeys. Among carniv-
orous animals, we have cat-like creatures, one of which is dis-
tinguished from all modern animals of its group by the long,
saber-shaped canines of its upper jaw, fitting it to pull down
and destroy those large pachyderms which could have easily
shaken off a lion ora tiger. Here also we have the elephants,
the mastodon, a great, coarsely-built, hog-like elephant,
some species of which had tusks both in the upper and lower
jaw; the rhinoceros, tbe hippopotamus, and the horse, ail of
extinct species. J. W. Dawson.

MorpPHouoe’icaL. That which has relation to the anatomical

THE USES OF MORPHOLOGY. 245

conformation of parts. Applied at times to the alterations
in the ‘form’ of the several parts of the embryo, in contra-
distinction to ‘ histological,’ which is applied to the transfor-
mation by which the tissues are gradually generated. In
comparative anatomy it is applied to the history of the modi-
fications of forms which the same organ undergoes in differ-
ent animals.

MorPHOL’oaGy is that branch of zodlogy, in its widest sense,

whic. treats of the general form (not outline) and organiza-
tion of animals, and the principles involved, as well as the
correspondence in the various forms of the several members
and parts, so far as they are comparable in any structural
characters, but entirely independent of the uses of the parts
and organs. It thus contrasts with animal physiology, which
treats of the organization in whole, so far as respects adapta-
tion to surroundings, as well as the various parts and organs,
so far as their uses and functions are concerned. To discover
the utility of organization in diverse animal forms and the
essential similarity in their mode of evolution, are the prin-
cipal problems within the province of morphology. Gill.

Mucous MEMBRANE (lining of alimentary, respiratory, and

genito-urinary tracts) consists of mucous membrane proper
and submucous tissues. The first consists of secretory tuber-
cles, follicles, and glands; the second of elastic connective
tissue (capillary blood-vessels and nerve-filaments) by which
the secretory surface is nourished. Its free surface is lined
with epithelial cells, related to the mucous tissues beneath as
the epidermic cells are to the skin ; affords an extensive sur-
face for the great functional glandular processes of nutritive
absorption and the elimination of effete excretory products.
Its special function is to secrete mucus, and thus protect its
passages from the contact, attrition, and irritation of their
moving contents. Mucus consists of water, mucosine, and
salts. When rich in mucosine, it is viscid and tenacicus ;
when salines predominate, it is scarcely more than transuded
blood-serum. E.. D. Hudson, Jr.

Musk-DeeEerR. A small deer of Central Asia ; a timid creature of

nocturnal habits, and is much hunted for its yield of musk,
which is obtained from a sac beneath the abdomen, on the
male alone. The flesh is esteemed, though that of the male

246 VOCABULARY.

is very rank and somewhat musky. It ranges from Siberia
to Tonquin. Johnson's N. U. Cye.
Montsac, of India, Java, &c., a small deer, but little over two
feet high. ‘The males have small horns; the females are
horniess. ‘Their flesh is excellent. The Chinese muntjac,
like the preceding, is often half domesticated, and is some-

times bred in European parks. Johnson's WW. U. Cye.

Myu’opon. Anextinct edentate animal, allied to the megathe-

rium. : Lyell.
N.

Nar’ WHAL, or SEA-UNICORN. It is most nearly related to the
white whale. Belonging to an order in which many of the
members never develop teeth at all, it, of all animals, is sup-
plied with a tooth altogether out of proportion to its size, and
it is, moreover, developed in utter contravention of the rules
of bilateral symmetry, which in every known case among
vertebrates govern the production of the teeth. In both
sexes the lower jaw is edentulous. The male, however, is
provided, on the left side of the upper jaw, with a tusk from
eight to ten feet long. It is straight, spirally grooved ex-
ternally, and hollowed within into a persistent pulp-cavity.
On the right side the corresponding tooth generally remains
hidden, smooth, and solid, within the jaw. In addition to
these, there are two small rudimentary molars concealed in
the upper jaw. The narwhal, which is considered one of
the greatest curiosities of natural history, attains to a length
of fifteen feet. Its single spiracle or blow-hole is situated on
the top of the head. H.C. H. Day.

NECRO’sIs, or death of a bone, corresponds to mortification of
the soft structures, and is as distinct from caries as mortifica-
tion is from ulceration. Necrosis is divided into four varie-
ties, namely: 1. Thescrofulous. 2. The superficial, or that
which involves the outer lamelle, and presents itself in the
flat and long bones. 3. That form which destroys the in-
ternal part of a bone, and in which the outer shell is not af-
fected. 4. That in which the whole thickness of the bone
dies, W. Williams.

O.
ODONTAL’GIA. Toothache.
ODONTOG’ENY. Generation or mode of development of the teeth,

\

A DUCK-BILLED MAMMAL. 247

ODONTOG’RAPHY. A description of the teeth.

Opon’TOID. ‘Tooth-shaped.

ODONTOL ITHOS. A sort of incrustation, of a yellowish color,
whica forms at the corone of the teeth, and is called ‘ tartar.’
It consists of 79 parts of phosphate of time, 12} of mucus, 1
of a particular salivary matier, and 7} of animal substance,
Soluble in chlorohydric acid. A species of infasoria, ‘ dentic-
ola hominis,’ has been found in it.

ODONTOL/OGY. An anatomical treatise of the teeth.

ORAL. Relating to the mouth or to speech.

ORAL EpiItHe’Lium. See ‘ Epithelium.’

ORNITHORHYN’cHus. An effodient (digging), monotrematous
mammal, with a horny beax resembling that of a duck, and
two merely fibrous cheek teeth on each side of both jaws, not
fixed in any bone, but only in the gum ; with pentadactylous
(five-fingered) paws, webbed like the feet of a bird, and
formed for swimming, and with a spur in the hinder feet,
emitting a poisonous liquid from a reservoir in the sole of the
foot, supplied by a gland situated above the pelvis, and by
the side of the spine. The animal is covered with a brown
fur. It is found only in New Holland, and is sometimes
called Water Mole. Bell.

As the name of the order imports, the alimentary, urinary,
and reproductive organs open into a common cloaca, as in
birds; mammary glands are present, secreting milk for the
young, which are born blind and naked; there are no prom-
inent nipples, and the mammary openings are contained in
slits in the integument ; M. Verreaux says the young, when
they are able to swim, suck in the milk from the surface of
the water, into which it is emitted. American Cyc.

‘Duck-Bill,’ the English name of the Ornithorhynchus par-
adoxus, found in Van Diemen's land and Australia. In its
bill-like jaws, its spurs, its monotrematous character, its non-
placenta] development, and its anatomy, it appears to be a
connecting link between birds and mammals. The Duck-Bill
is the only animal of its genus. It is about fifteen inches
long; it climbs trees with facility, and digs burrows, often
thirty feet long, in the river bank, with one opening above
and another below water. It inhabits ponds and quiet
streams, swimming about with its head somewhat elevated,

248 VOCABULARY.

often diving for its food, which consists of insects and other
small aquatic animals. Johnson's N. U. Cyc.
Of all the mammalia yet known, the Ornithorhynchus
seems the most extraordinary in its conformation, exhibiting
the perfect resemblance of the beak of a duck engrafted on —
the head of a quadruped. Dr. Shaw.
According to Ernst H. Haeckel, these animals “are be-
coming less numerous year by year, and will soon be classed,
with all their blood relations, among the extinct animals of
our globe.” '
Os. A bone; also a mouth,
OsTEOL’oGy. The part of anatomy which treats of bones.
OSTEO-SARCO’MA. Disease of the bony tissue, which consists in
sofiening of its laminew, and pheir transformation into a fleshy
substance, analogous to that of cancer, accompanied with
' general symptoms of cancerous affection. The word has also
often been used synonymously with ‘spina ventosa,’
O’VARIES (ovum, egg). The two organs in oviparous animals
in which the ova, the generative product of the female, are
formed. They are termed by Galen ‘ testes muliebres,’ since
they are in women the analogues of the testes inmen. The
ovaries in adult women are situated on either side of the
uterus, in the iliac fosse; they are included in the two pel-
vic duplicatures of the peritoneum, which are called the
broad ligaments. Each ovary is also attached by a round,
fibrous corl—the ovarian ligament—to the side of the uterus,
and by a lesser fibrous cord to the fringed edge of the Fallo-
pian oviduct. The ovary is an oblong, ovoid, flattened body,
of a whitish color and uneven surface. It is $ to $ an inch
thick, # of an inch wide, and 1 inch to 14 long; it weighs
from 1 to 2 drachms. EF. Darwin Hudson, Jr.
OzE’NA. An affection of the pituitary membrane, which gives
occasion to a disagreeable odor similar to a crushed bed-bug.

P.

PALEONTOL’0GY. The study of ancient beings. The science
which treats of the evidences of organic life upon the earth
during the different past geological periods of its history.
These evidences consist in the remains of plants and animals
imbedded or otherwise preserved in the rocky strata or upon
their surfaces, and in other indications of animal existence,

— -

FOOTPRINTS IN THE SANDS OF TIME. 249

such as trails, footprints, burrows, and coprolitic or other
organic material found in the rocks. Pythagoras, Plato,
Aristotle, and other ancients, allude to the existence of ma-
rine shells at a distance from the sea: it was considered cen-
clusive evidence that the rocks containing them had formerly

been submerged beneath the ocean. Am. Oye.
Papin’LA. ‘The end of the nipple, or an eminence similar to a
nipple.

The minute elevations of the surface of the skin, tongue,
&c. They serve to increase the extent of surface for vascular
distribution, or subserve sensitive or mechanical purposes.
Some contain one or more vascular loops; others, nervous
elements. Some are surmounted by dense epithelial fila-
ments, as those which give the roughness to the tongue.

Webster.

PaR’ASITE. Parasites are plants which attach themselves to
other plants, and animals which live in or on the bodies of
other animals, so as to subsist at their expense. The mis-
tletoe is a parasitic plant, the louse a parasitic animal.

PARVETES. A name given to parts which form the inclosure or
limits of different cavities of the body, as the parietes of the
cranium, chest, &c.

PaRoTIp. (‘About the ear.’) The largest of the salivary
glands, seated under the ear and near the angle of the lower
jaw. It secretes saliva.

PAaTHOL’oa@y. The branch of medicine whose object is the
knowiedge of disease. It has been defined ‘diseased physiol-
ogy,’ and ‘pliysiology of disease.’ It is divided into general
and special.. The first considers diseases in common; the
second the particular history of each. It is subdivided into
internal and external, or medical and surgical.

Preuvis The part of the trunk which bounds the abdomen
below.

PERIODONTITIS. Inflammation of the membrane that lines the
socket of a tooth.

PER‘0s’TEUM. The periosteum is a fibrous, white, resisting
medium, which surrounds the bones everywhere, except the
teeth at their corone (crowns), and the parts of other bones
that are cdvered with cartilage. The external surface is
united, in a more or less intimate manner, to the adjoining

250 VOCABULARY.

parts by areolar tissue. Its inner surface covers the bones,
whose depressions it accurately follows. It is united to the
bone by small fibrous prolongations, and especially by a pro-
digious quantity of vessels, which penetrate their substance.
It unites the bones to the neighboring parts, and assists in
their growth, either by furnishing, at its inner surface, an
alsuminous exudation, which becomes cartilaginous and at
length ossifies, or by supporting the vessels which penetrate
them to carry the materials of their nutrition.

Prrrous. Resembling stone; having the hardness of stone,

PuLEeGMON. Inflammation of the areolar texture, atcompanied
with redness, circumseribed swelling, increased heat and
pain, which, at first, is tensive and lancinating and afterward
pulsatory and heavy. It is apt to terminate in suppuration.

Pra MATER (tender mother), so named because it nourishes the
nerve-centers. The innermost covering of the brain and
spinal cord ; a fine plexus of blood-vessels, dipping into the
brain’s convolutions, forming the velum interpositum in the
third and the choroid plexus in the fourth ventricle. A
small part (over the crura and pons) is not very vascular, but
tough and fibrous, while that of the spinal cord, with which
it is intimately connected and of which it is the neurilemma,
is still less vascular. It is partly composed of longitudinal
fibrous bundles, and is abundantly supplied with nerves and
lymphatics. The tunica vasculosa of the testes is also called
pia mater. Johnson’s N. U. Cye.

Pirv’ITarRy. Concerned in the secretion of muscus or phlegm.

PITUITARY MEMBRANE. The mucous membrane which lines
the nasal fossee, and extends to the cavities communicating
with the nose. It is the seat of smell.

Puas’MA. See ‘ Liquor Sanguinis.’

PLEISTOCENE. A term used to denote the newest tertiary de-
posits. Johnson's N. U. Cyc.

PLY ocENE. In geology, the term applied to the most modern
of tertiary deposits, in which most of the fessil sheils are of
recent species. Lyel.

With regard to animal life, the Pliocene continues the con-

ditions of the Miocene, but with signs of decadence. The
Pliocene was terminated by the cold or Glacial period, in
which a remarkable lowering of temperature occurred over

hires F s 4

THE WOOLLY RITINOCEROS: 251

all the northern hemisphere, accompanied, at least in a por-
tion of the time, by.a very general and great subsidence,
whicu laid all the lower part of our continent under water.
This terminated much of the life of the Pliocene, and re-
placed it with boreal and arccic forms, some of then, like the
great hairy Sibe ian mammoth aud the woolly rhinoceros, fit
successors of the gizantic Miocene fauna. J. W. Dawson.

Pow’ypus. A naine given to tumors which occur in mucous
membranes especially, and which have been compared to cer-
tain zojphytes. Polypi may form on every mucous mem-
brane. They vary much in size, number, mode of adhesion,
and intimate nature, Fibrous polypi are of a dense, compact
texture and whitish color. They contain few vessels and do
not degenerate into cancer. The scirrhous or carcinomatous
are true cancerous tumors, painful and bleeding.

Pons VAROLII. An eminence at the upper part of the medulla
oblongata, first described by Varolius. It is formed by the
union of the crura cerebri and crura cerebelli.

PosTe’RIOR. Opposed to ‘ anterior,’ which see.

PTER’yGorD. A name given to two processes at the inferior
surface of the sphenoid bone, the two laminz which form
them having been compared to wings.

Pytor’ic. That which relates to the ‘pylorus.’ An epithet
given to different parts.

Pyruto’Rus. A ‘gate, a ‘euardian.’ The lower or right orifice
of the stomach is called ‘pylorus’ because it closes the en-
trance into the intestinal canal, and is furnished with a cir-
cular, flattened, fibro-mucous ring, which causes the total
closure of the stomach during digestion in that organ. Itisa
fold of the mucous and muscular membranes of the stomach,
and is the ‘ pyloric muscle’ of some authors.

Q.

QUADRUMA’NA. (Quatuor, ‘four,’ and manus, ‘hand.’) A name
employed by Blumenbach (in 1791) as an ordinal designation
for the monkeys, lemurs, and related types, man having
been isolated as the representative of a peculiar order named
Bimanus. The views thus expressed were for a long time
predominant ; but a closer study of the structure of the forms
indicated b¥ those names has convinced almost all living
naturalists that they were erroneously separated, and the two

202 ; VOCABULARY.

types are now generally combined in one order named Pri-

mates, under which head man and the monkeys are com-

bined together in one sub-order (Anthropoidea), and con-

trasted with the lemurs, which constitute another sub-order

(Prosimie). Theodore Gill.
ik.

Rectum, The third and last portion of the great intestine. It
forms the continuation of the sigmoid flexure of the colon,
occupies the posterior part of the pelvis, and extends from
the sacro-vertebral articulation to the coccyx (rump or crup-
per bone), before which it opens outward by the orifice ealled
the ‘anus.’

R&e’IME. Mode of living; government, administration.

REG’IMEN. The rational and methodical use of food and of
everything essential to life, both in a state of health and dis-
ease. It is often restricted in its meaning to ‘diet.’ It is
sometimes used synonymously with hygiene (health).

Rv’MINANT. A division of animals having four stomachs, the
first so situated as to receive a large quantity of vegetable
matter coarsely bruised by a first mastication, which passes
into the second, where it is moistened and formed into little
pellets ; these the animal has the power of bringing again to
the mouth, to be rechewed, after which it is swallowed into
the third stomach, from which it passes into the fourth,
where it is finally digested. Webster.

(Several well authenticated cases of human beings who
ruminated their food are on record.)
Ss.

Sarco’MA. Any species of excrescence having a fleshy consist-
ence.

SCHNEIDERIAN MEMBRANE. See‘ Pituitary membrane.’

ScLERO?’ Ic. A heavy, resisting, opaque membrane, of a pearly
white color and fibrous nature, which covers nearly the pos-
terior four-fifths of the globe of the eye, and has the form of
a sphere truncated before.

SELLA TurR’ctca. (Turkish saddle.) A depression at the upper
surface of the sphenoid bone, which is bounded, anteriorly
and posteriorly, by the clinoid processes, and lodges the pitu-
itary giand. It isso called from its resemblance to a Turkish
saddle.

THE MORSE, ASS, MULE, QUAGGA, 253

SrPpTuM. A part intended to separate two cavities from each
other, or to divide a principal cavity into several secondary
cavities. ;

Srerous. Thin, watery. Relating to the most watery portion
of animal fluids, or to membranes that secrete them,

Sou’reep. An animal whose hoof is not cloven; one of a group
of animals with undivided hoofs; a solidungulate. Webster.

The family ‘Solipeda’ consists of several species of horse,
namely, the ass, the mule, and the quagga. Youatt.

SpHENOID. Wedge-shaped.

SPHENOID BoNE. An azygous (single) bone, situate on the me-
dian line, at the base of the cranium. It articulates with all
the bones of that cavity, supporting them and strengthening
their union. Its form is singuiar, resembling a bat with its
wings extended.

SprnA VENTO’SA. See ‘ Osteo-sarcoma.’

Sryiom. (A style, a peg, a pin.) Shaped like a peg or pin.

SUBMAXILLARY (from sub, ‘under,’ mazilla, ‘the jaw’). That
which is seated beneath the jaw.

SuprpuRA’TION. Formation or secretion of pus. It is a frequent
termination of inflammation, and may occur in almost any of
the tissues. This termination is announced by slight chills,
by remission of the pain, which, from being lancinating, be-
comes heavy; by a sense of weight in the part, and, when
the collection of pus can be easily felt, by fluctyation. When
pus is thus formed in the areolar membrane, and is collected
in one or more cavities, it constitutes an ‘abscess.’ If it be
formed from a surface exposed to the air, it is an ‘ulcer,’ and
such ulcers we are in the habit of establishing artificially in
certain cases of disease.

Supra. A common Latin prefix, signifying ‘above.’

Suture. A kind of immovable articulation, in which the bones
unite by means of serrated edges, which are, as it were, dove-
tailed into each other. The articulations of the greater part
of the bones of the skull are of this kind.

Sym’puysis. A union of bones. The bond of such union. The
aggregate of means used for retaining bones ¢7 situ (natural
situations) in the articulations. The name symphysis has,
however, been more particularly appropriated to certain artic-
ulations, as the ‘ symphysis pubis,’ ‘sacro-iliac symphysis,’ &.

ae

254 VOCABULARY.

T.

THLEOsts (or TELHOSTE!). The name of that sub-class of fishes |
which embraces the great majority of living species, and so
designated (by Johannes Miiller) on account of the ossified
condition of the skeleton in all the representatives of the
group. Theodore Gill.

TERATOLoGyY. A treatise on monsters.

TeR’TIARY. Third; of the third formation. In geology, a
series of strata, more recent taan the chalk, consisting of
sandstones, clay beds, limestones, and frequently containing
numerous fossils, a few of which are identical with existing
species. It has been divided into Eocene, Miocene, and. Pli-
ocene, which see. Dana.

TINcTU’RA Myrru&. (Tinctureof Myrrh.) Tonic, deobstruent
(removing obstructions), antiseptic (opposed to putrefaction),
and detergent. It is chiefly used in gargles, and is applied
to foul ulcers, spongy gums, Xe.

Tissuk. By this term, in anatomy, is meant the various parts
which, by their union, form the organs, and are, as it were,
their anatomical elements. ‘ Histological anatomy ’ is the
anatomy of the tissues, which are the seat of the investiga-
tions of the pathological anatomist. The best division, in-
deed, of Giseases would be according to the tissues mainly

implicated.
Tox’opon. ‘A gigantic, pachydermatous quadruped, now ex-
tinct, having teeth bent like a bow. Brande.

TRANSUDA’TION. (To sweat.) The passage of a fluid through
the tissue of any organ, which may collect in small drops on
the opposite surface, or evaporate from it.

TREPHINE’. The instrument which has replaced the trepan in
some countries. It consists of a simple, cylindrical saw, with
a handle placed transversely, like that of a gimlet; from the
center of the circle described by the saw a sharp little per-
forator, called the center-pin, projects. The center-pin is
capable of being removed, at the surgeon's option, by means
ofakey. It is used to fix the instrument until the teeth of
the saw have made a groove sufficiently deep for it to work
steadily. The pin must then be removed. Sometimes the
pin is made to slide up and down, and to be fixed in any
position, by means of a screw. ~

MINUTE, ROD-SHAPED PARASITES. 255

Tro’car. An instrument used for evacuating fluids from cavi-

ties, particularly in ascites (serous fluid in the abdomen, or,
more properly, dropsy of the peritoneum), hydrocele (watery
tumors), &c. A trocar consists of a perforator, or stylet, and
acanula. The canula is so adapted to the perforator that,
when the punciure is made, both enter the wound with facil-
ity ; the perforator being then withdrawn, the fluid escapes
through the canula,

TUBERCLE. Miliary tubercles are minute, bright, rounded, trans-

lucent particles, called granula, granulations, &&. When
they coalesce, forming larger bodies and undergo a change of
color they are known as crude or yellow tubercles. As age
advances, the center is apt to be occupied by a giant cell, a
large multi-nucleated body, whose boundaries and processes
are hard to define, because they shade off gradually into the
surrounding tissue. They are the result of an inflammatory
process, because they can be produced by the introduction
of mechanical irritants. In some instances we have reason
to believe miliary tubercles may become organized and a
cure result. Tuberculosis is hereditary, and there is some
good evidence to prove it is contagious; it is also inuculable,
and “‘ breeds true,” always producing its kind, if it produces
anything, but it has not been satisfactorily proved to have a
specific virus. T. E. Satterthwaite.

(Dr. Koch of Berlin says (1882) tuberculosis is caused by
minute, rod-shaped parasites (bacilli) ; that he has inoculated
animals with them, producing tuberculosis; that he has
dried the sputum of phthisical patients for two months and
has bred the parasites artificially for several generations
without their losing the power of inoculation ; that when
the sputum is dried the air is infected ; that bovine and hu
man tuberculosis are identical; that tuberculosis can be
given to man by the milk (perhaps flesh also) of tuberculous

cows. The pardsites are about soeoth of an inch in length.)

Tunic. An envelop; as the tunic of the eye, stomach, bladder.
TuRG&S’CENCE, Superabundance of humors ina part. ‘ Tur-

gescence of bile’ was formerly used to denote the passage of
that fluid into the stomach and its discharge by vomiting.

TymMPANITEsS. A flatulent distention of the belly; tympany.

Also inflammation of the lining membrane of the middle ear,

256 VOCABULARY.

U~.

Un’GULATS. Shaped like a hoof. Having hoofs, as ungulate
quadrupeds. Webster.

U’vzaa (from wvea, a grape). The choroid coat of the eye; the
posterior layer of the iris.

U’vreous. Resembling a grape; applied to the choroid coat of
the eye.

Vv:

Vas’cuLAR. That which belongs or relates to vessels—arterial,
venous, lymphatic—but generally restricted to blood-vessels
only. ‘Full of vessels.

VELUM Pauta’TI. The soft palate.

VER’TEBR&. The bones which form the spinal column.

Vis’cus (plural, vis’cera). One of the organs contained in the
great cavities of the body; any one of the contents of the
cranium, thorax, or abdomen; in the plural, especially ap-
plied to the contents of the abdomen, as the stomach, intes-
tines, &c. Webster.

Vit’rEOus. Of, pertaining to, or derived from glass. The vit-
reous humor of the eye is so called because it resembles
melted glass.

Z..

Zo6u’ocy. That part of biology (science of life) which relates
to animal life, and, as generally understood, the science
which treats of the structure, classification, distribution, hab-
its, and derivation of living animals. In its broadest sense,
however, zodlogy includes the structure, relations, and his-
tories of extinct as well as living forms; but this branch of
the science is generally considered by itself under the title
of ‘paleontology.’ The derivation and life-histories of many
groups of animals have been found written in the records of
the past, and many mysteries, not only of relation but of
structure, have been solved by going back to find dwarfed
organs in full development and widely-separated forms linked
together. The zodlogy of the future will therefore include
the animal life of both the past and the present.

J. 8S, Newberry.

ZYGOMAT’Ic. That which relates to the zygoma or cheek bone.

—

APPENDIX,

RECENT DISCOVERIES OF FOSSIL HORSES.

BY J. L. WORTMAN.

THE contributions to the knowledge of the extinct Perisso-
dactyla,* made during the last two or three years in this
country, are of an important character, since they demonstrate
the actual existence of types heretofore hypothetically assumed.
The living representatives, the horse, tapir, and rhinoceros,
constitute but a small fraction of this large order when com-
pared with the fossil forms already known. One of these,
however, the horse, displays the most specialized structure to
be found within the limits of the order.

Many years have elapsed since the first discovery in the
Tertiary rocks of Europe of horse-like remains, which are
regarded by paleontologists in the light of direct ancestry of
existing equines. Since then the discovery of the remains of
these animals in the same geological horizons in this country,
by Drs. Hayden and Leidy, has strengthened the belief in the
descent of the horse from very different ancestral types. Entire
skeletons, obtained from the ‘“‘ bone beds” of the West, display

* Odd-toed. The Perissodactyla may be defined as mammals having
both pair of limbs fully developed and adapted for walking or running,
the toes having termina] phalanges, ineased in strong corneous sheaths,
developed as hoofs. These characters, however, apply to two other orders
also, the Artiodactyla (cloven-hoofed or even toed), and the Amblypoda
(short-footed), both of which, hewever, possess many anatomical Ciffer-
ences from the Perissodactyla, particularly in the structure of their hind
limbs.

258 _ APPENDIX.

their osteological characters to such an extent as to leave no
doubt as to the correct determination of their true affinities.

It is much to be regretted, however, that many of these
animals have received different names from different authors, a
fact specially conducive to confusion in the nomenclature of the
science. It appears that the only way to obviate this difficulty
is by strict adherence to priority in the employment of a name,
provided it is accompanied by a competent description, and the
use of such characters as will distinguish the animal named
from its nearest allies. If unaccompanied by these differential
characters, it is a nomen nudum, and can have no claim what-
ever to rank with those that have been properly defined. I
mention these facts with the hope of establishing a criterion by
which to judge which name it is proper to retain and which it
is proper to discard ; and, to elucidate the subject, I will gives
the names of a few animals that have been discovered during
the past forty years.

In 1841 Prof. Richard *Owen described the remains of a
Lophiodon-like* animal, from the London clay of Eocene age,
to which he gave the name Hyracotherium.+ Subsequently he
described a nearly allied genus, from the same deposit, under
the name Pliolophus.{ In Hyracothcrium the molar and pre-
molar teeth are different, both above and below. In Pliolophus
the last, or fourth inferior premolar, is like the first true molar,
a character which separates the two genera satisfactorily. The
specimens described by Prof. Owen do not display clearly the
number of digits either possessed, but he expresses the opinion
that Pliolophus has three toes on the posterior limbs.

* The Lophiodons were first described by Cuvier. They were allied to
the tapir. They derive their name from the structure of the true molars,
which have their crowns crossed transversely by two crests or ridges of
dentine, covered with a layer of ename). The last lower molar has also a
small posterior lobe. The premolars are more simple in structure and
compressed, resembling the first premolars of the tapir. The upper molars
also resemble those of the tapir, but approach in some respects those of
the rhinoceros. The diastema, or toothless interval between the canine
and premolar teeth, was much shorter than in the tapir. Several species
have been described from the Eocene of France and England, but little is
known of the skull or skeleton. No true Lophiodon is yet certainly known
in this country.—0O. C. Marsh.

+ Transactions London Geological Society, 1841, pp. 203-208.

t Loc. Cit., pp. 54-72, 1858.

CONFUSION IN NOMENCLATURE. 209

In 1872 Prof. O. C. Marsh found the remains of an animal in
this country iu deposits of Eocene age to which he applied the
name Orohippus.* This genus was originally founded on the
molar teeth, which he compared with those of Anchitherium.
He subsequently ascertained that it possessed four toes on the
anterior and three on the posterior limbs.+ He also proposed an-
other genus under the name of Lohippus, which he compared
with Orohippus, stating that the last inferior premolar is like
the first true molar, a character which at once distinguishes it
from Hyracotherium. As he assigns no other dental characters
to this genus sufficient to separate it from Pliolophus, with
which, according to his description, it otherwise agrees, and as
the digital formula in the Lophiodons generally is 4—3, the
two names must be regarded as synonymous. This may like-
wise be said of the genus Orotherium,$ which Prof. Marsh
distinguishes by the bifid condition of the antero-internal lobe
of the inferior molars. This character is also ascribed to a
number of molar teeth discovered by Dr. Joseph Leidy in the
Bridgér Eocene, which he referred to the genus Lophiotherium,
a near ally of Pliolophus. But as this is a character of very
doub:ful generic value in this group of animals, these names
must be regarded as synonymous with Piivlophus.

Assuming then that the most generalized form in the ancestry
of the horse hitherto known was Hyracotherium, with a digital
formula of 4—8 and teeth of the Lophiodon pattern, we are
now prepared to take a step backward to the primitive five-toed
ancestor, Phenacodus. But before entering on a discussion of
this interesting form, it is necessary to mention the discovery
of another genus, from the Lower Hocene beds of Wyoming,
which proves to be a near ally of Hyracotherium. This genus
Prof. Cope calis Sys'emodon,| and assigns as his reasons for
separating it from Hyracotherium the circumstance that it dis-

* American Journal Science and Arts, 1872.
+ Loc. Cit., p. 247, 1874.

+ Loc. Cit., Nov., 1876. The genera Orohippus, Eohippus, Miohippus,
and Pliohippus have not in my estimation been distinguished from genera
previously described ; hence my reasons for adopting names more in
accordance with the prevailing nomenclature of the science.

§ Loc. Cit., 1872.

{ American N.turalist, 1831, p. 1018.

260 APPENDIX.

plays no diastemata (spaces) behind the superior canines, while
in the latter there are two. This fossil (from New Mexico) was
first described by him under the name Hyracotherium tapiri-
num, but the discovery of better specimens demonstrates its
claim to the rank of a new genus.

PHENACODUS.

Phenacodus, one of the most important of recent paleon-
tological discoveries, was first made known by Prof. Cope in
18738,* from several molar teeth which he obtained from the
New Mexican Wasatch. Its systematic position in the mam-
malian class was, however, involved in considerable uncertainty
till the discovery of the greater part of the skeletons of two
distinct species of this genus by the writer in the Wyoming
Wasatch during the summer of 1881, which afforded Prof,
Cope the means of determining its true position and elucidat-
ing the many important and interesting points its osteology
teaches.+ It possesses five well developed toes in functional

* Paleontological Bulletin, No. 17, Oct. 1873, p. 3.

+ Frior to the discovery of these skeletons no characters had been found
among the Ungulata which indicate a group connecting the Perissodactyla
with the elephants and hyrax.* But it is now necessary to create a new
order, which Prof. Cope designates the Condylarthra. (Paleontological
Bulletin, No. 34. Dec. 1881, p. 177). The characters on which this division
reposes are found in the carpus and the astragalus (hock or ankle bone)
and their manner of articulation. The Perissodactyla are distinguished by
the fact that the scaphoid articulates with two bones below, and the astra-
galus articulates inferiorly by two nearly flat facets with the cuboid and
navicular bones. They are divisible into ten families, including forty-eight
genera, variously distributed throughout geologic time; but as only four
of these families concern us for the present, I will spare the memory of the
reader by not discussing the classification of the others. The first to which
attention may be directed is the Lophiodontide, embracing eight well de-

* A gray-haired, rabbit-sized pachyderm, with 4 toes on the ferefeet, 3
on the hind, a mere tubercle for a tail. molars resembling (in miniature)
those of the rhinoceros, 2 large, triangular, curved, tusk-like incisors in the
upper jaw, and 4 straight ones in the lower. Cuvier says the upper jaw, in
youth, has 2 small canines, but Marsh’s dental formula is: Incisors, 1—2,
1—2; canines, 0O—0, 0—0; premolars, 4—4, 4--4; molars, 3—3, 3—3=34.
There are several species, the African being able to climb a tree. The
Cape hyrax is called the reck-badger or rock-rablit. The hyrax was long
classed among the redents, and was also called a miniature rhinoceros,
There are various affinities between the elephant and some rodents—(1) in
the size of the tusks ; (2) in the molars being often formed of parallel lam-
inze ; (3) in the form of several of their bones.

RELATION OF PHENACODUS TO AMBLYPODA. 261

us2 on all the feet, of which the first is the smallest; the
median is the largest and is symmetrical within itself. The
feet are considerably shortened and were probably semiplanti-
grade ; in fact the feet of this animal constitute an approach
to the Amblypoda.* The dental formula is: Incisors, 3—3,

fined genera, which are not positively known to have cxisted later than
the upper Eocene epoch, It may be recognized (1) by the possession of
four toes on the anterior and three on the posterior limbs; (2) by the
molar and premolar teeth being different ; (3) by the non-separation of the
anterior and posterior external cusps of the superior molars by an external,
rib-like pillar. The next family is the Chalicotheriida@, to which ten genera
are referred. The digital formula is the same as in the Lophiodontida, as
is also the relation of the molar and premolar teeth. The only distinction
is found in the separation of the anterior and posterior external lobes by a
vertical ridge. The remains of this family range from the lower Eocene to
the middle Miocene. The third family is the Paleotheriidce, having three
toes on each foot. The molars and premolars are alike, and the inferior
molars possess perfect double crescents. The fourth family is the Hguida,
in which the digital formula is reduced to one toe on each foot. The mo-
lars and premolars are alike and highly complex in structure. It is to this
family that all the existing horses belong, and it has been traced as far
back as the upper Miocene strata. The Condylarthra, on the other hand, are
effectually separated from the Perissodactyla by the non-alternating posi-
tions of the carpals and by the possession of an astragalus whose distal face
is convex in every direction, as in the carnivora, and unites with the navic-
ular alone. These families are the Phenacodontide and Meniscotheriide
whose remains have been found so far only in the lower Eocene deposits
of this country. It is interesting to note that they are the most generalized
of any known Pcrissodactyla and supply a link long sought in the evolu-
tion of the later and more specialized forms of this order.

* There has probably been no discovery among the ungulates since the
finding of the Amblypoda that has proved equal in interest and importance
to the discovery of this group (the Phenacodontid). The descent of ail
the ungulates from the Amblypoda has been held by Prof. Cope for some
time, but that it took place from any known genera of this order the ¢om.-
paratively specialized condition of the tecth of the latter distinctly forbids.
This moderate complexity of the teeth among Eocene mammals is a strik-
ing exception, especially when associated with such a low grade of organi-
zation of other parts as we find in these animals. The explanation of this
fact must, in my judgment, be sought for in their large size and in the pos-
session of powerful canine teeth, which insure them greater immunity from
the attacks of fierce carnivorous contemporaries. With these means of
defense, they could take up their abode where food better adapted to their
wants was furnished. Hence we can with perfect consistency look for
a rapid modificatign of these organs, accompanied by slight change in
others. In order to make the connection complete between them and the
Phenacodonts, there should yet be found an Amblypod with bunodont

262 APPENDIX.

5—3; canines, 1—1, 1—1; premolars, 4—4, 4—4; molars, 3—8,

9 fo)

5—5=44; that is 44 functionally developed teeth. The molars
are of the simple four-lobed pattern, resembling in this respect
the suilline Artiodactyla or hogs and peccaries; in fact on this
account jt is a matter of some surprise that the animal should

molars, reduced canines and a more elongated foot. An approach to this
condition, as far at least as the molars are concerned, is found in a new
form recently described by Prof: Cope under the name Manteodon (pro-
phecy tooth). The Amblypoda, says Prof, Cope in his Report on Capt.
Wheeler’s Survey (W. 100th Mer., Pt. ii, Vol. IV, p. 233), are as yet con-
fined to the Eocene period exclusively, and are found both in Europe and
this country. In points of affinity to the hoofed orders generally they
occupy an interesting and important position, being in all probability the
oldest and affording the most generalized condition known among the
ungulates. The brain capacity is exceedingly small in proportion to the
size of the other parts of the skeleton, and from casts made from the brain
case itself we are warranted
in assigning these animals
a position among the low-
est mammalia; they are
lower in brain development
even than any of the J/ar-
supials. The feet are very
short, are provided with
five fully developed toes,
and have their entire plan-
tar and palmar surfaces ap-
plicd to the ground, as in
the modern bears. The as-
tragalus is greatly flattened
from above downward, and
is primitive and character-
istic. It displays on its in-
ferior surface flattened ar-
ticular facets for both na-
vicular and cuboid bones
which share the articula-
tion about equally. On the
superior part, the surface
articulating with the tibia
is almost flat, a conditien
Rignt hind-foot of a species of Coryphodon (Amblypod), half which must have rendered
naturel sige (COPE), the ankle joint capable of
very little movement, and
giving to these animals a peculiarly awkward and shambling gait. It is
not difficult to perecive that these small-brained, five-toed, and plantigrade
Amblypoda could easily have furnished a starting point for both the Artio-
dactyla and Perissodactyla, and, as we have good reasons to believe, did
give origin to the Proboscidea or elephants.

HORSES WITH TEETH SIMILAR TO REPTILES’. 203

turn out not to belong to the suillines, But when the evi-
dence of derivation drawn from other sources is considered,
and the geological period is taken into account, the structure
of the teeth is preéminently in accordance with the expecta-
tions of the evolutionist. It is important to notice in this con-
nection that Prof. Cope ventured the prediction in 1874* that
the guadritubercular or four-lobed bunodont + molar was the
primitive pattern in which the more complicated selenodont {
molar of the later ungulates had its origin. That this predic-
tion is now proved there can be no question, and the passage
from this simple type of tooth to the highly complieated forms
illustrated in this article has, I think, been close and cousecu-
tive and intimately associated with reduction in digits.

The Phenacodontide present considerable variety as far as
their family is at present known. Prof. Cope has described
five genera, as follows: Phenacodus, Anacodon, Protogonia,
Periptychus, and Anisonchus. The first two are from the
Wasatch horizon, while the last three were derived from the
underlying Purco beds. Periptychus shows a peculiar sculp-
turing of the outside of the molar teeth, similar to that seen in
many reptiles, and is the only mammal known to possess it.
The molars of Anacodon lack distinct tubercles, a character
which assigns it the lowest position in the family. Phenacodus
approaches nearest to the Lophiodons in dental character and
is taken for illustration. As all but Phenacodus and Peripty-
chus are known from their teeth only, it may be necessary on
the discovery of the character of their feet to refer them to new
families. The definition of the family given by Prof. Cope is
as follows: Molar teeth tubercular; molars and premolars
different ; five toes on ail the feet.§

MENISCOTHERIUM,

The Meniscotheriide has been recently established for the
reception of the single genus Meniscotherium, discovered by

* Journal Academy of Natural Sciences, Philadelphia.
_ + Teeth of simple structure, with short crowns and low, blunt tubercles
on their fice.

+ Teeth of complicated structure, with high and uniformly broadened
crowns, the face presenting a complex folding of the enamel plates,

§ Paleontological Bulletin, No. 34, Dec., 1881, p. 1%,

264 APPENDIX.

Prof. Cope in the Wasatch beds of New Mexico, and described
by him in his report to Captain Wheeler, already cited. It
was formerly arranged in the Chadicothertide, near Chalicothe-
rium, with which it agrees in all essential dental characters,
The recent discovery of the bongs of the feet shows that they
display tae characteristic peculiarities of the Condylarthra, to
which group it must be referred, Its digital formula is
unknown, hence we must rely on the specialized crescentoid
pattern of the molars for the family definition. It is proper to
remark here that reduction in digits in the Perissodactyia is
usually accompanied by specialization of the molar teeth. In
this case, therefore, I would venture the prediction that its
digital formula will be found to be 4—38, with the outer toes
somewhat reduced. The value of the digital formula as a
character in the definition of the families of the Perissodactyla
is of high standard. This may likewise be said of the rela-
tion of the molar and premolar teeth, but in a less degree.
The tubercular or crescentoid structure of the molars, however,
is capable of such intergradation, which increase of our knowl-
edge demonstrates, that it must be accepted as provisional
only, and not entitled to rank equal in value to either of the
other two characters in defining the family.

The genealogy of the horse as now indicated is as follows:

Equus, Equus,
Protohippus, Hippotherium,
Anchippus, Paioplotherium,
Anchitherium,
Mesohippus,
Lambdotherium,
Hyracotherium,
Systemodon.

PERISSODACTYLA -

AMBLYPODA, Hyedonta (Cope).

CONDYLARTHRA- . Meniscetherium,
! Phenacodus.

265

IOSES.

-
a

NATURE'S METAMORP

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qOOf ALOT WoT *p OO} pury oy} Woazy OMY PUB I1OJ BY} WOLF 90} VUO JO WOLJOUPod VB OWLS JO JOOS PUTT E ‘(adog) ozs jeinyeu
Jey | wenpoowusaa unpioyjoovdhyy JO JOOS oLOJ JJOT “B “(UBULJAO MW) OZ[S [BILYBU JVY - snamundd snpoopuayd Jo yoo} puiy yoT 'T
‘“LHUUT DHL AT NMOHWHS SV NOLLATIOA

Waly
ey

Bros

266 APPENDIX.

TEETH FROM PHENACODUS TO EQUUS. 24

1.—Left upper molar of a species of Phenacodus, nat. size (Cope) az is
the antero-exicrnal, pe the postero-external. ai the antero-internal and pi
the postero-internal Joves respectively. They are low and obtuse and con-
stitute the principal cusps of the crown, ace and pee are the anterior and
posterior cross crests; they are rudimentary and represented by isolated
tubercles in this animal, but are developed into important structures in the
more specialized genera. y (ihe lobe is drawn too large) is the rudimental
external rib separating the antero and postero-external cusps, An antero-
basal Jobe arising as an outgrowth from the cingulum or ledge surrounding
the base of the crown is strongly marked in some genera.

2.—Left lower molar of same, nat. size. z represents a low, indistinct-
ly marked ridge, passing from the postero-external to the antero-internal
cusps pe, aé. The antero-internal cusp ai is sometimes double, x is the
heel, which is so strong in the last molar as to be called a fifth lobe. It is
connected by a faint ridge with the postero-external cusp pe. The four
principal cusps ae, pe, ai, pe hold the same relation to the crown as in the
upper molar,

3.—Right upper molar, of a species of Lambdotherium, in which the an-
tero and postero-external cusps dé, pe are separated by an external vertical
ridge, y; nat. size (Cope).

4.—Last lower molar (left side), of same; nat. size, The antero-in-
ternal lobe is divided into twe distinct tubercles, ai, ai’; the ridge k is
strong and prominent. The breadth of the tooth is accounted for by the
fact that it is the last molar, the first and last molars being about a third
broader than the others. The teeth are of a morecomplicated pattern than
those of Phenacodus. It is important to notice that while the teeth of the
lower Eocene genera of this family (Lambdotherium and Paleosyopous) re-
semble very strongly the tecth of the Jower forms of the Lophiodons in the
shortness of their crowns and approach to the bunodont type, the latter
possess longer cusps and simulate the selenodont forms in the crescentic
section of some of them.

5.—Left upper molar of Anchitherium aureliauense, nat. size (Gaudry).
The four principal cusps ae, pe, ai, pi are considerably lengthened and con-
nected by high ridges, acc, pec, which pass in an oblique direction across
the crown. The elevation of the cusps and crests give increased depth to
the valieys. The anterior basal lobe is reduced and the external rib y is
strong. The crown is further complicated by the addition of the lobe Z.

6.—Right upper molar of a species of Hippotherium. The valleys, which
are deepened by the lengthening of the cusps and ridges, are filled by a
thick deposit of cement, but the cement, as the cnt shows, has been re-
moved. The points of the cusps and ridges are unworn. The four princi-
pal lobes ae, pe, ai, pi hold about the same relation to each other. The
cross crests acc, pec have their obliquities increased, and the anterior bends
around on the inner part of the face and becomes confluent with the pos-
terior ridge pec. The lobe 7, which is conic in Anchitherium, is elongated

‘in a transverse direction to the crown, so as to close the posterior valley

and join the po&terior external cusp pe with the posterior crest pee. Addi-
tional vertical pillars are developed on the cross ridges. The teeth resem-

268 APPENDI

ble those of the horse very strongly, the crowns of the incisors showing
the peculiar invagination seen in the incisors of the horse.

7.—Left lower molar of Hippotherium gracile, three-fourths natural size
(Gaudry). The lobe ai’ is now completely separated and the ridge & rises
to a level with the other cusps. The heel / is also elevated and connected
by a strong ridge. The filling up of the valleys by a deposit of cementum
and the consequent attrition in mastication produce*a marked change in
appearance from that seen in Anchitherium, but by close observation the
strictest homology is seen to exist.

8.—Left upper molar of a species of Hguvs (modern horse) natural size.
The internal lobes ai, pt are connected with the cross ridges acc, pec. . The
only difference of generic value between Lquus and Hippidium (a near rela-
tive of ihe horse) is seen in the relative size of the antero and postero-in-
ternal lobes ai, pi; in Equus ai is greatly enlarged and somewhat flaitened;
in Hippidium the lobes are almost equal.

What has caused these changes? In regard to tooth struc-
ture generally, Mr. J. A. Ryder has given us a most excellent
treatise ““On the Mechanical Genesis cf Tooth Forms,” * in
which he shows that the jaw movements of animals are
intimately related to the modification of the component lobes,
crests, and ridges of the crowns of the molar teeth. He also
points out that the restricted jaw movements, in which the
mouth is simply opened and closed, are associated with the
bunodont molar; that the various kinds of excursive mandib-
ular movements have been develoved progressively ; ‘‘ that as
these movements have increased in complexity there has been
increase in the complexity of the enamel foldings.”

If we attempt to apply these facts to the ancestry of the horse,
it is by no means difficult to perceive that gradual change of
habitat, causing a corresponding change in diet, would also
compel greater and greater mobility of the mandibular articula-
tion for proper trituration of the new food, The movements of
the lower jaw in these animals have assumed a lateral direction,
which affords, as I believe, a sufficient explanation for the
broadening of the crowns and the lateral flattening of the cusps.
The obvious effect of force continually applied in this direction
would be to wrinkle the enamel covering of the cusps and
ridges, thereby producing the accessory pillars seen in the
higher types. By this method, I believe, a more and more
complex grinding surface has been produced.

* Proceedings Academy Natural Sciences, Philadelphia, 1878.

CAUSE OF DIGITAL REDUCTION. 269

The cause of digital reduction is another interesting inquiry.
Bunodonts as a rule:are dwellers in swamps and forests and
live on nuts, berries, and roots. If they are compelled to for-
sake their natural habitat and live in the open field, either
modification or extinction will follow. Once in the open field
speed becomes a desideratum as a condition of safety, and the
foot with a reduced number of digits possesses many advan-
tages over the polydactyle one.

Prof. Cope has shown (American Naturalist, April, 1881)
that in plantigrade quadrupeds the extremities of the toes are
arranged in a semicircle, when they are all applied to the
ground. Jn the act of running the 1._el and wrist are raised,
throwing the weight of the body on the median digits. An
infinite repetition of this posture in digitigrade animals unable
to withstand the attacks of their enemies and whose only
escape was in flight, the strengthening of the median digits,
and the consequent reduction of the outer ones, would follow
according to the law of use and disuse of parts. This subtrac-
tion of toes has progressed step by step until the modern one-
toed horse has been reached.

In summing up an article in the Kansas City Review of Science
and Industry, Mr. Wortman says:

“T dare say that if all the intervening individuals between
Phenacodus and Equus could be produced classification would
be utterly impossible, so insensible would be the gradation.”

The forms already known appear to point to the inevitable
conclusion that the modern horse is the product of the slow
but improving processes of evolution, which are still in opera-
tion, and are being aided by all the skill known to modern
science. A discussion of tiie subject is almost superfluous, for
the illustrations, like deeds, speak louder than words.

Note.—Pliny (B.C. 28) says Cesar had a 5-toed horse (the forefeet), which
was represented in his (Pliny’s) day by a statue ; also that Epigenes says the
Babylonians had a series of observations on the stars for a period of 720,000
years, inscribed on baked bricks. Berosus and Critodemus say 490,060.
(Vol. ii. pp. 221-317.) Baked bricks have been found buried in the valley
of the Nile at adepth to require the annual deposits of that river for 9,000
years (72 feet.) May they not some day be valuable aids to science as well
as history ? Their stories can be better,imagined than described

270 APPENDIX.

THE VIEWS OF AN EVOLUTIONIST.

THE following ‘‘review” of HoRsEs’ TEETH, written by
Mr. R. M. Tuttle for Johnstons’ Dental Miscellany, contains so
much of interest on the subject of evolution that I think no
apology necessary for inserting it here instead of putting it
among the other press reviews at the conclusion of the volume:

“The author of this work modestly suggests that it may be
of value to the veterinary profession end also to horsemen and
farmers. We have no hesitation in going further and affirm-
ing that it contains much of an instructive and interesting
character for dentists, and all scientific and thoughtful men.
The day has gone by when humanity laughed or grew angry
(according to its temper at the moment) at the mere suggestion
that man has any relationship with the lower animals beyond
their submission to his will and his right to lead them to the
slaughter-house. The movement of thought in the direction
of Evolution is battled against by some eminent thinkers. The
book before us does much to upset the arguments of these
thinkers and to support the theory they denounce. But there
is a middle position for those who neither agree with the theory
of a separate creation for every genus nor with the develop-
ment of animal life from one germ form. This position may
be described in the words of Tennyson as a ‘sunless gulf of
doubt.’ Doubt, however, is not always sunless; and besides
to admit a doubt is at least frank, and we prefer it to being
dogmatic. Still even believers in a separate creation for every
genus cannot but admit that, notwithstanding the. great
diversity in the animal kingdom, there is a oneness of princi-
ple, a common style of architecture, so to speak, pervading all
animal life, which we sez in the structure of teeth, arms, legs,
wings, &e.

“The construction of a horse’s teeth points to the inevitable
conclusion that he is a vegetarian, but the various changes in
the dentition of a long line of fossil horses indicate that he was
once probably carnivorous, or perhaps omnivorous. Teeth,
like other parts of the body, are influenced by use; the change
is not so obvious, but it is no less certain. As the volume

THE WEDGE OF EVOLUTION. 271

before us affirms, for example, the canine aud remnant teeth
have been much reduced in size, and, if Mr. Darwin’s theory
is correct, are probably in the course of ultimate extinction.
Now, the function of a canine tooth is to tear, not grind. If
animals that now use their canines for tearing flesu were com-
pelled to subsist on vegetable food, there would perhaps be no
marked change in a generation, but there certainly would be
in a series of generations, We therefore conclude that horse
dentures have adapted themselves to a gradual but great change
in the animal’s mode of existence, a gradual departure from
the original custom of subsisting on food which demanded
tearing teeth, and that it took to vegetarianism naturally.
Fossil remains would force this conclusion on us, however
much we might desire to doubt it. But why should we have
such a desire? To admit development, say some, is but the
thin end of the wedge of Evolution. Beitso. It is the fune-
tion of scientific wedges to split old and false notions, and who
ever heard of a man putting the thick end of a wedge in first?
Whether development is the thin end of the wedge of Evolu-
tion or not we do not care much to inquire. If a man studies
horses’ teeth of to-day as well as those of human beings, he
will come to the conclusion that in both there are signs of great
development when compared with the teeth of thousands of
years ago. He will observe not change merely, but signs of a
higher order of being—signs of an evolution of the superior
from the inferior.

‘To some people Evolution is a bugbear, and the idea that
human beings are capable of physical development is not much
less. We advise such people not to read Mr. Clarke’s book. It
would trouble them. They might cast it into the fire and thus
waste their money. But intelligent seekers after truth, those
who find the ‘gulf of doubt’ in which they are floundering
too sunless for their light-loving souls; those who are not
afraid to meet the doctrines of scientific men face to face, may
read this work with profit. Without desiring to disparage its
author, we may say that its chief value lies in the fact that it
is composed largely of selections from the works of men of
special knowledge on the subject of the treatise and of various
germain subjécts. Much credit is due to him for collecting in
so compact a form such a large quantity of valuable matter,

R212 x APPENDIX.

which was scattered over cyclopedias, translations of learned
secieties, and other costly books.”

Mr. Tuttle, in a letter to me (a few words of which have
been interpolated in the foregoing article), in substance says:

‘“« At the close of the Eocene period there were three distinct
types of animals descended from a common ancestor that are
now represented by the horse, tapir, and rhinoceros.* Let us
suppose that a pair of animals gave birth to the offspring which
were to be the parents of these three types. What would be
the process of development? These animals, with their mates,
by some means get separated. ‘The parent of the future tapir
goes one way ; that of the rhinoceros stays at home, while he
who is to beget the horse wanders away from the marshes and
rivers to the dryer land. Circumstances over which he has no
adequate contro] place him where alligators, crocodiles, and
other animals that he has been accustomed to attack with his
tushes are absent. His feet, which are many-toed, broad, and
adapted to walking in the mud, now tread hard soil ; his canine
teeth, which were used in tearing flesh, now find little employ-
ment; his neck, from constant stretching as he crops the foliage
of the bushes, lengthens ; a more rapid gait is acquired by a
gradual contraction of the toes and the lengthening of the legs,
and eventually this modified animal becomes a horse. Thus is
told in a few words what I believe has Leen gcing on in the
course of hundreds of thousands, perhaps millions cf years.”

It is noteworthy that a young man like Mr. Tuttle should
entertain views similar to those of such an experienced evolu-
tionist as Prof. Cope. It is not difficult to believe that the
bear-like Amblypoda, which Prof. Cope thinks were the com-
mon progenitors of the horse, tarir, rhinozeres, elephant, &c.,
were carnivorous, and there certainly is some analogy between
the supposititious animal just described by Mr. Tutile and tke
Amblypoda. Change of food was probably as instrumental in
producing the great physical changes in early fossil animals as
change of habitat and climate. And change of food does not

* Compare with quotation from Prof. Huxley in third note, pp. 65-66;
also with same from Prof. Owen, pp. 106-7.

FOOD A FACTOR IN EVOLUTION PROBLEM. 273

necessari:y entail extinction, unless it be food directly opposed
to the animal’s nature; and it raatters not if the change is
compulsory, for changes of taste may be either natural or cul-
tivated. For example, children relish food they cannot eat
when adult, and vice versd, which is natural; and an appetite
for some foods may be cultivated at any age. Again, food
probably causes much of the change in tame boars and other
animals that become wild, and vice versd, Still it is not strictly
correct to say that the horse as such was ever carnivorous, for
an animal that was the common ancestor of so many diverse
animals was as much one as the other.

In 1878, in a hastily written prospectus of a work that Dr.
C. D. House designed to publish, in conformity with his
(House’s) views, I said the horse was probably once earnivor-
ous. Thinking Dr. House to be mistaken, I wrote to Dr. Leidy
of Philadelphia, asking his opinion on the subject. He agreed
with me.

THE ORIGINAL HOME OF THE HORSE.

THERE is no doubt that the original home of the horse is not
Europe, but Central Asia; for since the horse in its natural
state depends on grass for its nourishment and fleetness for its
weapon (safety), it could not in the beginning have thriven
and multiplied in the thick forest-grown territory of Europe.
Much rather should its place of propagation be sought in those
steppes where it still roams about in a wild state. Here too
arose the first nations of riders of which we have historic
knowledge, the Mongolians and the Turks, whose existence,
even at this day, is as it were combined with that of the horse.
From these regions the horse spread in all directions, especially
into the steppes of Southern and Southeastern Russia and into
Thrace, until it finally found entrance into the other parts of
Europe, but not until after the immigration of the people.
This assumption is at least strongly favored by the fact that
the further a district of Europe is from those Asiatic steppes,
t.¢., from the original home of the horse, the later does the
tamed horse seem to have made its historic appearance in it.
The supposition is further confirmed by the fact that horse-

ait APPENDIX.

raising among almost every tribe appears as an art derived
from neighboring tribes in the East or Northeast. Even in
Homer the ox appears exclusively as the draught-animal in
land operations at home and in the field, while the horse was
used for purposes of war only. Its employment in military
operations was determined by swiftness aloue. That the value
of the horse must originally have depended on its fleetness,
can easily be inferred from the name that is repeated in all the
branches of the Indo-European language, and signifies nearly
‘“‘hasteaing,” ‘‘quick.” The same fact is exemplified by the
descriptions of the oldest poets, who, next to its courage, speak
most of its swiftness —VTire Popular Science Monthly for June,
1882.

ELEPHANT TOOTH-GERMS.

MM. Pouczer anp CHasrit (Le Progrées Médical), having
examined the germs of the teeth of a fetus of an elephant in
the Jurdin des Plantes, have concluded that the general opin-
ions on this subject are not exact. Since the works of Robin
and K6liker, it has been assumed that there is produced on
the surface of the gum a primary epithelial bud (bourgeon), that
Pouchet calls the epithelial plate and K6lliker the adamantine
organ or enamel, which sends out a prolongation destined to
form a temporary tooth, and afterward a second prolongation
for a permanent tooth. The more recent experiments seem to
prove that the permanent teeth are not given forth from the
neck of the temporary, and that there is no secondary adaman-
tine organ. In the elephant, where there is no second set of
teeth, the same plate or layer appears, together with the same
prolongations. The two faces of the epithelial pro‘ongation
do not have the same structure ; the inuer face is composed of
cylindrical cells, while in the outer face there is a mingling of
epithelial and tissue cells —W. Y. Med. Times, Feb. 1881 (trans-
lated by Dr. T. M. Strong).

The deductions of MM. Peuchet and Chabrit may be correct
in principle, but it is a mistake to say the elephant has only
one set of teeth, for he has six or more, and may in fact be said

THE ELEPHANT TEETHING ALL THE TIME, 275

to be always teething. The following facts are partly based
on Cuvier, Owen, and: Wm. Jacobs:

The grinders, which are constantly in progress of destruction
and formation, are not deciduous in the ordinary sense, for they
succeed each other horizontally instead of vertically, and not
more than one wholly or two partially (one on each side in each
jaw) is in use at one time. As the fore part of the tooth in use
is worn away by attrition and its roots diminished by absorp-
tion, its successor pushes it forward (a movement that appears
to be facilitated by the direct backward and forward action of
the lower jaw), and a large part of the replacing tooth is in
use for some time before the first is entire'y shed. Thus a
grinding surface is ready all the time. The milk teeth are cut
eight or ten days after birth, the upper preceding the lower,
and it is about two years beiore they are entirely displaced by
the second set. The second set is in use, but gradually dis-
appearing, from the second year to the sixth, when the third is
fully in position ; it in turn serves till the ninth year, when
the fourth set is in position; and thus it continues to the end
of the animal’s life—10) or even 150 years. Each succeeding
tooth requires at least a year more than its predecessor to be
completed.

The grinders are remarkable for their size and the complexity
of their structure, the upper and lower teeth being much alike.
They are composed of ivory (dentine), enamel, and a large
quantity of cement. The crown is short in proportion to the
depth of the base or root, only a small part appearing above
the gum. In the Asiatic species the crown is composed of
transverse, vertical, enamel-plated dentine ridges, about half
an inch apart, and joined together by cement. The ridges are
nearly straight and are tooth-like in appearance. The ridges
are good indicators of age, the first set of teeth having 4, the
second 8 or 9, the third 12 or 18, the fourth 15, and so on to
the seventh or eighth, which have 22 or 23. In the African
species the crown is studded by lozenge-shaped projections in-
stead of ridges. A tooth of the elephant Columbus, an excellent
specimen, which may be seen in Worth’s Museum (New York),
weighs 12 pounds ; its preadth is 7 inches (the aggregate of
the six back teeth of the horse) ; thickness, 24; length, 11.

276 im APPENDIX.

It has only 18 crown ridges, and is therefore little above a
medium-sized tooth.* The crown resembles a small Belgian
paving stone, while the taper of the root resembles that of a
heart.

The elephant is a vegetarian, and the consiruction of its
grinders is a striking example of the adaptation of the teeth of
an animal to its food.

The tusks, two in number and belonging to the upper jaw,
are shed but once. The deciduous tusks cut between the filth
and seventh months and are shed about the end of the first
year, their roots being considerably absorbed. , They rarely
exceed 2 inches in length and 4 of an inch in diameter. About
two months after the shedding of the temporary tusks, the
permanent, which are situated to the inner side of and behind
the former, emerge and continue to grow throughout life. They
have an enamel coat, but are inostly composed of ivory, a
remarkably fine and elastic form of dentine (differing somewhat
from the dentine of other teeth), and are hollow for a consider-
able part of their length. They are deeply imbedded in the
skull. Sir Samuel Baker found one 8 feet long with 22 inches
girth to be imbedded 381 inches.

The tusks, which are formidable defensive and offensive
weapons, and which correspond to the canine teeth of other
animals, vary mucn in length, weight, and curvature. Gordon
Cumming found a tusk in Africa that measured 103 feet and
weighed 173 pounds. The average, however, is not over 7 feet
and 109 pounds. They are generally smaller in the female
than in the male, but according to Cuvier the African species
are the same in this respect. In the Indian elephant some have
a pronounced upward curve, some are nearly straight, while
others resemble the letter S. They are sometimes used as
levers in uprooting mimosa trees whose crown of foliage is
beyond the reach of the trunk. In Ceylon, where the elephant
lives chiefly on grass and herbage, the tusks are generally
absent in both sexes. The bullets sometimes found in the
ivory are probably first lodged in the pulp cavity and then
carried to the solid part by growth.

* Mr. L. G. Yates of Centerville, California, says fossil elephant molars
weighing 25 pounds have been discovered in that State.

HUMAN (HUMANE) DENTISTRY. 277

A large elephant weighs 7,000 pounds. The Indian elephant
is 10 feet in hight, the African 12; askeleton in the St. Peters-
burg Museum is 16}.

HUMAN TEETH.
FILLING CHILDREN’S TEETH.*

FinirneG the deciduous or first set of teeth prevents decay
and consequent injury to the second set,} alleviates pain, facil-
itates speech,t mastication, and regularity in the growth of the
second set, aids in keeping the breath pure, and is conducive
to health at a very critical time of life. They should be filled
as long as filling will preserve their usefulness, and at all times,
for some are shed as early as the fifth or sixth year, others
as late as the eleventh or twelfth. Any of the usuai fillings
wili answer, the sole object being to arrest decay and “aid
somatic development” (Odell). Children should be taught to
use a brush and proper dentifrices. Defective teeth are often
the result of improper diet during utro-gestation. Drs. J. Allen
and G. M. Eddy say that mothers do not eat enough bone-
producing food, such as oatmeal, bread made from unbolted
flour, &c., but admit that such foods do not assimilate in every
case. Dentists differ as to the advisability of the use of
anesthetics in treating children.

The teething period is longer than is usually supposed. It
begins about the seventh month before birth$ and continues

* The object of this brief article is merely to call attention to an impor-
tant subject. My own attention was directed to it by Mr. E. A. Rockwell
in an interesting article in the New York Sun. Readers who wish to study
the subject are referred to the elaborate works of dentists. Besides the
dentists mentioned above I have consulted Drs. G. H. Rich, F. Abbott, and
C. E. and J. S. Latimer, all of New York.

+ Dr. T. P. Wagoner (Knightstown, Ind., Dental News) approves the
above, and in addition says the development of a permanent tooth may
be retarded by a dead deciduous tooth.

t Haller and other physiologists give minute accounts of the effects
produced by teeth in articulating the various letters of the alphabet.—
Bostock. ~

§ For the development of human tooth-germs from the seventh week
till birth see page 46.

278 APPENDIX.

till the age of 17 or 25 years. The annexed cut (Farrar) repre-
sents (above the dotted line) an upper deciduous set of teeth,
1, 1, central incisors, erupt between the 5th and 6th months;
2, 2, lateral incisors, 7th and 10th months ; 3, 3, canines (eye
teeth), 12th and
16th months ; 4, 4,
5,5, all molars, 14th
and 86th months.
Total, 20. The low-
er teeth usually
precede the upper
by a few weeks.
6,6 do not belong
to the deciduous

erupt between the
fifth and sixth
years, are usuaily classed with them, and frequently decay
beyond remedy before the mistake is discovered.

Dr. J. N. Farrar (New York), to whose works I am indebted
for information, says (Missouri Dental Journal, April, 1880) :
“The statistics in this country show that out of about 80 peo-
ple of all classes only one has sound teeth. This is the result
of a combination of causes—systemic disturbances from clinfate,
food, crossing of races and types, and neglect. Most of the
cavities are caused by anatomical imperfections or overcrowd-
ing, nearly all of which develop before the thirty-fifth year.
* * * The science of dentistry, however, has checked much
of this suffering, and at this time (1879) there are 12,000 dentists

y SH} HN BN NY
Aryeh 3S

annually packing into tooth-cavities about half a ton of gold—_

$500,000. The estimated gold coinage value in this country is
about $150,000,000; this sum, at the rate gold is used for fill-
ings, would be transferred to graveyards in 300 years. The
value of the cheap fillings is about $100,000, and there are
annually manufactured about 3,000,000 artificial (porcelain)
teeth. * * * If $100 is put on interest (7 per cent.) at the
birth of a child, it ought to pay all dental expenses till the age
of 80 years; but if the child’s teeth are neglected, increased
dental bills result, with poor teeth at best. The only question
remaining is, is the baby worth $100?” .

set, but, as they |

Ee

INDEX.

ABNoRMAL DENTITION, human, 128;
horse, 142.

Abnormal Teeth, 115-125.

Abnormal Tooth, description of, 123.

Absorption of roots of foals’ teeth,
48, 70-1; do. e.ephant, 275-6; den-
tal journal on, 288.

Alfort Veterinary College, 14), 142.

Amblypoda, the, 257; description
of, 261-2.

Americas, the, richness of fossil re-
mains in, 103-113.

Anacodon, fossil horse, 263.

Anchippus, fossil horse, 96.

Anchitherium, fossil horse, 96, 111.

Auchitherium aureliauense, teeth of,
266-7 ; toes of, 265.

Animal Kingdom, diversity yet one-
ness of principle in, 270.

Animal, 3 supposititions, 272.

Anoplothere, teeth of, 65.

Antelope montana, tushes of, 78.

Apparatus, dental, exuberance of
particular parts of, 141-3,

Appendix, fossil horses, evolution,
original home of horse, clephant
and children’s teeth, 257 277.

Apsyrtus, advice of, 116.

Arcades (of tecth) anomalies in form
of, 140, 141.

Aristotle, mistake of, 69.

Arloing, M., resectiou of nerves, 217,

Arma‘illo, the, 229.

Artiodactyla (hous, &¢.), 257, 262.

Ass, experiment on an, 217, 218,

Baprneton, B., 242.

Bacon, Francis, theory of, 15.

Buer, Von, comparisons by, 81.
Baker, §., report of, 18i, 182.
Batrachia, the, 229, 230.

Bay, Surgeon, discovery of, 117.
Bell, C., discoveries of, 217, 218.
Bell. Thomas, theonies of, 26-7, 83-4.
Berger-Perriere, discovery of, 116.
Berzelius, discoveries of, 15.

Birds, fossil, teeth of, 114.

‘ Bishoping,’ modus operandi of. 211.

Black, Surgeon, experiment of, 29.

Blaine, Surgeon, fractured jaw, 197,

Blastema, nature and color of, 34-5.

Blumenbach, on quadrumana, 251.

Boar, the masked, grinders of, 10.

Boar, wild, tame, changes in, 84, 273.

Boll, De., tooth pulp, 41.

Bojanus, disesvery of, 52.

Bond’s *Deutal Medicine,’ extract
from, 128, 129.

Bouley, M. H., development of teeth,
45; grinders, 62; formation of
enamel, 64; growth of teeth dur-
ing life, 73; diseases of teeth, 158 ;
diseases and dentistry of teeth, 139-
182; swallowing teeth, 192, 198 >
removal of fractured jaw, 197, 198.

Bourgelat, Prof., milk molars, 69.

Brandt, L.. length of incisors, 74;
age of Spanish horses, crib-biters
and mules, 215; age by shape of
teeth, 215.

Brewster. B. § , letter from, 292.

Broadhead, G. C., account of fossil
tooth, 112, 113.

Broderip, Mr., a whale’s tooth, 79.

Burns, John, description by, 239.

Butterfly, the, transformations of, St.

CacHALot, the, 79,

Calcigerous, origin of word, 18.

Catile, teething period of, 91, 92.

Camel, the, teeth of, 66,

Camper, P., temporary canines, 52.

Canines, temporary, 51, 82.

Calculus Concretions, 192. 193, 280.

Caries, cause of, 144~154 ; 165-178;
symptoms of, 148-154; different in
different teeth, 151: odor of, 153;
treatment of, 155-171; treatment
after trephining sinuses for, 176;
other dental cases, 177-193 ; con-
founded with glanders, 176, 180,
185; definition of, 231.

280

Cartwright, W. A., report of, 193; j

iracture of jawbone, 196.
Caucasian Races, teeth of, 99.
Cement, the, 9; size of tubes of, 16;

use of, i7; mistaken for tartar, 17; |

vascuiarity of, 17; thinness of, 17;
color of, 13 ; resemblance to bone,
23; germs of, 43; a proiecting
Varnish, 59,6); microscopical char-
acter ef, 133.

Chabrit, M., tooth-germs, 274.

Chalicotheriidz (fossil horses), 260.

Chandler, C. F., on albumen, 227.

Cnaauveau, A., harmony of teeth with
general system, 11; development
of tooth-germs, 41, 42 ; description
of ircisors, 58, 59, 60; growth of
teeth during life, 73.

Cherry, W. A., shedding teeth, 50-1 ;
judging age by shape of teeth, 204.

Chevrotain, 78 ; description of, 282.

Clayworth, Sarg., report of, 197.

Coleman, Surgeon, discovery of, 116.

‘Columbus’ (elephant), tooth of, 275.

Coluber Scaber (serpent). 12i.

Comparative Anatomy, 233.

Conrad, T., discovery of, 113.

Complex grinders, cause of, 268.

Concomitant Variation, a factor in
evolution probiem, 98.

Condylarthra, the, 250-1, 264.

Cope, E. D., editor American Natur-
alist, 113; physiological homolo-
gies, 233; discovers Phenaccdus
(teeth) and other fossil horses,
259-269 ; opinion of the Amblypo-
da, 261-2.

Copybara, the, grinders of, 10; de-
scription of, 283.

Coughing and Teething, treatment
for, 92.

Crib-biting, effect of on teeth, 212-
13

Cumming, G., elephant tusk, 276.

Cuvier, F., 16; note on, 63; bones
and teeth of recent and fossil
horses, 106; ophthalmic ganglion,
221; elephant teeth, 275.

Dana, Prof., geology, 240:

Dandini, J., silver and golden hued
teeth, 25-6.

D’Arooval, teething, 87.

Darwin, C. R., tushes of various ani-
mals, 77, 78, 79 ; changes in human
teeth, 99.

Dawson, J. W., geology, 249; mio-

cene period, 244; pliccene period, |

250.
Day, EH. C. H., narwhal, 246.
Deciduous teeth, retention of, 129.
Delafond, M., on trephiving, 161.
Denenbourg, F., report of, 123.
Dental Cysts, importance of study
of, 115 ; microscopical character of

INDEX.

teeth in, 118 ; reports and theories
on, 115-126.

| Dental Canal, the, 381, 224, 234.

Dental Cysts, 115-1x6.

Dental Nerve, the, 224-226.

Dentinal, origin and use of word, 8,

Dentinal Puip, network of looped
capillaries of the, 33-4.

Dentimal Star, 59; description of,
209.

Dentinal Tubes, office and color of,
22, 23; their two curvatures, 23;
dichotomously branched, 131, 133 ;
diameter of, 152; length of curves,

33.

Dentine, the, &, 14.

Dentine Germ, 43, 59.

Dentition Fever, 93.

Dentition, permanent, 53-74,

Dentition, temporary, 47-52.

| Dentition, third, cases of, 128.
| Digital reduction, cause of, 269.

| Enamel, the, 10;

Dinoceras mirabilis (fossil), horns
and canine teeth of, 286.

Diverticula, use of, 22, 235.

Dog tooth-germs, grafting of, 27-8.

Draper, J. W., obligation to, 4.

Dugong, the, 79; description of, 235.

Dunglison, R., development of teeth,
45 ; diseases of teeth, 137; calculi,
193; vocabulary, 227-256.

Evpy, Dr., children’s teeth, 277.

Edinburgh Veterinary College, re-
port of, 179, 180.

Editor Veterinarian, comments of,
184; report of, 201, 202.

Elasmothere, the, great size of, 107;
enamel festoons of molars of, 107;
co:necting link between horse and
rhinoceros, 107.

Elephant, great quantity of cement
in grinaers of, 10; unique mode
of cutting and shedding several
dentitions; size, structure, &e.,
274-7; affinities with rodents, 260.

Embryo, human, transformations of,
81-2 ; definition of, 236.

Embryology, 80-82.

tubes of, 18, 19;
color of, 19; membranous sheaths
of, 59; plications of, 106.

Enamel, the two rings of, 59.

Enamel-Fibers, direction of, 20;
curves of, 26; form and size of, 20;
diameter of, 134.

Eocene (period) fossils of, 236.

Equidse, the, teeth of, 261.

Evolution, doctrine of 77-9, 98-9. 237 ;
253-6) ; from inferior to superior,
271; a buebear, 271.

Hxostoses, 17, 116.

FAENKEL, discoveries of, 15.
Falconio, Surg., discovery of, 118.

INDEX.

Ferguson, P. B., development of
teeth, 45; grinders, 62 ; the forma-
tion of enamel, 64; growth of
teeth during liie, 73; diseases of
teeth, 158 ; diseases and dentistry
of horses’ ieeth, 139-162; swallow -
ing teeth, 192, 193.

Filling children’s teeth, 277.

Fleming, G., dental cysts, 115-119;
fractured jaw, 195, 196; on glan-
ders, 199.

Food, for foals, 5C; for tooth-cough,

2; for unequal wear of grinders,
143; after trephining for caries,
159, 162; for defective teeth, im-
proving skin, fever, convalescence,
&c., 162-4; sifting of, 171; changes
caused by, 272; bone-producing,
277 ; sugar for horses, 3U.

Forthomme, M., milk canines, 52.

Fossil, cat-like animal, a, 244.

Fossil, definition of, 114.

Fossil, hog-like elephant, with tusks
in both jaws, 244.

Fossil Horses, cause of changes in
teeth of, 268; do. reduction in
toes of, 269. (See Horses, fossil.)

Fossil Horses, recent discoveries of,
257-2AP. ‘

Fossil Tooth, a diseased, 173.

Fractured Jaws, 194-202.

Fungns Hematodes, 173; definition
of, 239.

GAMGER, J., report of, 120-2.

Ganglion, nature of, 220-1, 239.

Garengeot. M., dental key, 156.

Generali, Prof., dental cysts, 116-19.

Geology, definition of, 240.

Gill, T., nature of teeth, 12; dental
formula for horse, 103; fossil birés’
teeth, 114; teeth from diverticula
(marsupials), 235; morphology,
245 ; quadrumana, 251, 252; tele-
osts, 254.

Girard, M., age by marks and shape,
206-7 ; dentinal star, 209.

Glanders, resembles caries of last

inders, 152-8; odor of, 153; may

e caused by ciries of teeth (ab-
sorption of pus), 160 ; sometimes
imaginary, 176, 180, 185; danger
from and prevalenee of, 199.

Gomphosis (tooth-artienlation), 72.

Goodsir, Prof., on tooth-germs, 125.

Goubaux, Surg., discovery of, 117%.

Gowing, T. W., on teeth, 172-72.

Grice, ©. S., report of, 123, 124.

Grinders, the 54; tables of, 6 ; fig-
ures formed by, 6%; contrasts
between, 41, 62; their own whet-
stones, 65; roots of (€8, 70: shed-
ding of, 70. 71 y activity of growth
and undivided hase of, 74.

Grouillé, Mage, dental cysts, 114,

281

Guanaco, 78 ; description of, 240.

Gubernaculuin Dentis, the, descrip-
tion of, 42.

Gums, shrinkage of the, 72, 74, 172,
181; affected by turgescence, 151;
nerves of, 225.

Guilt, Surg., discovery of, 117.

Gutta-peicha as a filling for teeth
and sinuses, 164,177; for children’s
teeth, 277.

HAECKEL, E. H., embryos, 81-2.

Harris, Prof., 3d dentition, 129.

Hartshorne, H., evolution, 237.

Haschischat ed dab, eflect of on
teeth, 25.

Haw of the horse’s eye (membrana
nictitans), description of, import-
ance of, and evil caused by ignor-
art grooms, 244.

Hayden, Dr., discoverics of, £57.

Hayes, B.. tooth-pulp, dentinal
tubes, cells and curves upon
curves, cement, enamel, &¢., 22-4;
diseases of teeth, 137.

Heard, J. M., obligation to, 216;
letter from, 292.

Heath, J. P.. report of, 200, 201.

Hénocque, M.. motor nerves, 217.

Herbert, W. H., age, 214, 275.

Hesperornis (bird), teeth of, 114.

Hesperornis regalis, teeth of, 114.

Hipparion, fossil horse, 95, 96, 111.

Hippotherivm, fossil horse, 264-7.

Hippotherinm gracile, 268.

Hippopotamus, canine teeth of, 63.

Histology, definition of, 241.

Hitcheock, C. H., on fossils, 114.

Hoeing, C. F., obligation to, 215;
letter from, 292.

Hog, canine teeth of, 63.

Horsburgh, J., report of, 175.

Horse, signification of word, 274.

Horse, the, theory of introduction
into America, 110; a vegetarian,
270; probably never carnivorous,
272-3; once used for war only, 274.

Horse Dentistry, argument in favor
of, 160 ; dental aud other journals
on, 287-202.

Horse, genealogy of, 264.

Horse, original home of, 273.

Horses, fossil, At acodon, 263; An-
chippus, 96, <64; Anchitherinm,
96, 111, 112, 264; Anchitherium
aurelianense, 205, 267; Anison-
chus, 263; Chalicotheriide, 2€0,
264; Kohippus, (supposititions),
259: Equids, 26% ; Equus caballrs
primigenius, 107; Equus compli-
eatus, 113; Equus curvidens, 107;
Equus fossitis, 106; Equus plici-
dens, 107; Equus primigenins, 107;
Hipparion, #5-6, 111, 112; Hippi-
dium, 248; Aippotherium, 264-7:

282

Hippotherium gracile, 268; Hyo-
douta, 264; Hyouippus, 112; Hyra-
cotherium, 250, 264-5; Lambdothe-
rium, 264-7; Lophiodon and Lo-
phiodontide, 2538, 250; Menisco-
therium, 263-4; Merycnaippus, 112;
Mesohippus, 97, 112, 204; Orothe-
rium, 209; Paleosyopous, 297; Pa-
leotheriidx, 261; Paleoplotherium,
264; Periptyehus, 263; Pliolephus,

258-9; Protogonia, 263; Protohip- |
pus, 112, 261; Systemodon, 259-64. |

(See confusion in nomenclature,
pp. 203-9.)

Horses, fossil, 95-98, 106-13 ; extinc-
tion of in South America, 10);
recent discoveries of, 257-26);
early progenitors of (Amblypoda)
possibly carnivorous, 272.

Horses, ‘*insane,”’ 105.

Horses without cars, 103.

House, C. D., size of tooth-germs,
31; on teething, 47-8; grinders,
62; remnant teeth, 103, 104; re-
moving a fractured tooth through
the nostril, 198, 199; operations
in Worcester, Mass., 199; idle talk
about glanders, 19); another prob-
able mistake, 273

Hudson, E. D., Jr.,, mucous mem-
brane, 245; ovaries, 248.

Hunter, J., theories ot, 24-27; enam-
el of grinders, 63; attachment of
teeth, 72; use of canines, 85; su-
pernumerary teeth, 123; proving
the formation of new dentine, 209.

Huches, J., dimensions of teeth, 49;
periosteum of teeth, 137.

Huxley, T. H., tapir, rhinoceros, and
horse, 65-6; fossil horses, 110-11.

Hyohippus, fossil horse, 112.

Hyracotherium, fossil horse, 258-64.

Hyrax, teeth of and affinities with
rhinoceros and elephant, 259.

IeuaNnopon, the, molars of, 63.

Incisors, the permancat, 53; length
of, 57; curvatures of, 57; Chau-
veau’s description of, 53-60; mi-
croscopic character of, 150-135.

Incisors, temporary, 47-52.

Inferior Maxillary Nerve, the, 223-24.

Jacoss, W., on elephant, 275.

Jaw, description of lower, 62.

Jaw Movements, changes in, 258.

Jaws, fractures of the, -94-292.

Jaws, human, chanees in, 33, $9-100.

Jennings, R., remnant tooth-germs
and remnant teeth, 104.

Know3son, J. C., bishoving, 211.

Koch, Robert, discovery of, 255.

Kolliker, Prof. Rudolf Albrecht, on
tooth-germs, 39, 40, 45, 274.

]

INDEX.

Larosss, Prof., dental cysts, 120.

Limbdotherium, fossil horse, 254-7.

Lampas, cause of, 88-91; laucing
recommended for, 87, Jl ; burning
for disapproved, 90-1.

Launcelet, the, comparison to, 81.

Lanzillotti-Buonsanti, Prof., on den-
tal cysts, 115-18.

Lecoq, Prof., canine follicles, 44;
temporary canines, 52; descrip-
tion of grinders, 69-7i; do. ca-
nines, 76-7; remnant teeth, 100.

Leeuwenhoek, discoveries of, 13.

Legros, C., experiments of, 2/.

Leidy, J., letter from, 101; fossil
ae 113; 257, 259; opinion of,

3.

Lincoln, A., 211.

Lion, the, canine teeth of, 83.

Liquor Sanguinis, the, 22, 242.

Lophiodon, teeth of, 258, 260.

Lubin, R., discovery of, 127.

Lyell, Mr., N. American fossil tooth
corresponding to 8. Amer., 110.

Macrops, Surg., experiences of, 117.

Madder, effect of on teeth, 24.

Magitot, E., 2%; development of
tooth-germs, -human fetus, 46,

Malpighi, discoveries of, 13.

Man, canine teeth of, 82, 83.

Man, early progenitors of, 80-3.

Manteodon, prophecy tooth of, 262.

Marks, dimensions of, 57, 585 two-
fold use of, 204; too much cement
in, 209, 210.

Marsh, O. C.. evolution of horse, 95-
98; no ‘mark’ in teeth of early
forms, 203; fossil birds’ teeth,
114; description of mastodon and
megatherium, 243; the Lophio-
dons, 258 ; Orohippus, 259.

| Mastodon, the, 109, 114, 243.

May C., report of, 178, 179. ~
Mayhew, E, the cement, 17, 18;
judging age by teeth, 207-8.

Mayo, Mr., experiments of, 218.

Megatherium, the, teeth of, 107, 108 ;
description of, 243.

Melanian Races, teeth of, 99.

Membrana Nictitans, in early pro-
genitors of man (Darwin), €;
nerve for in horse, 222; descrip-
tion of, 244.

Meniscotherium, fossil horse, 263-4.

Merychippus, fossil horse, 112.

Mesohippus, fossil horse, 97, 112.

Miocene (period) fossils of, 244.

Miohippus, fossil horse, 112.

Molars, bunodont, 263.

Moluars, seleno‘lont, 263.

Molars, the, 54; inclination of, 54;
description of, 60-71; microscop-
ical character of, 130-35. |

Moon-Blindness, cause of, 105,

ae

INDEX.

Moore, T., a mountain herb, 25.
Morphology, definition of, 245.
Morton, Prof., treatise by, 193.
Mules’ ‘Teeth, telling age by, 215.
Miller, Prof., discovery of, 14-5.
Muntjac-Deer, 78, 246.
Musk-Deer, 78, 245.

Mylodon, the, 108, 246.

NARWHAL, the, tushes of, 79; de-
scription of, 246.

Nature barricading disease, 139, 209.

Newberry, J. 8., zodlogy, 256.

Niebuhr, opinion of, 25.

Nippers, the, use of word, 47.

Nomenclature, confusion in, 258-9,

OpoONTOBLASTS, the, 31.
Olontolithos, the, 17, 247.
Odontornithes (birds), teeth of, 114.
Odontonecrosis, 138.

Odontrypy, operation of, 138.

Oblinger, O. P., discovery of, 118,

Ophthalmic Nerve, the, 219-22.

Ornithorhynchus, the, 80, 247.

Operating, rules for, 154-160,

Oreste, Surg., discovery of, 138.

Orohippus, fossil horse, teeth of, $6,
large tnshes of, 97; toes of, 97;
size of animal, 112; name of, 259.

Osteo-sarcoma, case of, 186,

Owen, R., dental science, 8, 10, 12-
22; tooth-germs, 382-37; breadth
and thickness, 49; temporary ca-
nines, 51; teething, 55; descrip-
tion of grinders, 64-63; teeth of
anoplothere. 65; do. ruminants,
65; do. tapir, 635; do. rhinoceros,
6;; do. megatherium, 107; rem-
nant teeth, 102; fossil horses’
teeth, 106-10} ; microscopical ajp-
pearance of horses’ teeth, 130-135;
diseases of teeth, 137; diseased
fossil tooth, 178, 174;
pair of nerves, 225, 225; discovers

2

Hyracotherium, 258; teeth of ele- |

phant, 275, tooth-vascularity, 29;

m .
probable circulation and proionga: |

tion of nerves in dentinal tudes, 30.

PALEONTOLOGY. definition of, 248,
Paleosyopous, fossil horse, 267.
Paleothere, teeth of, 63.
Paleotheriide, fossil horses, 261.
Parker, Willard, on caries, 251,
Parnell, C., remnant teeth, 102.
Parrot-Mouth, 157. 16S.
Pathology of the Tecth, 136-174,
Percivall, W., teething, 86-83; lam-
pas, 838-99; diseases of teeth, 158,
135: ophthalmic ganglion, 921.
Periosteum, elasticity of, 72 ,74; def-
inition of, 249-59.
Periptvychns, a fossil horse with teeth
resembling a serpent’s, 263,

the fifth |

283

gb x roe gaaaae (odd-toed mammals),

257-64.

Pessina, Prof., discovery of, 215.

Phenacodus (earliest fossil horse),
description of, 260-264.

Pierce, Dr., opinion of, 287.

Plasse, M., mouth-serew 156.

Pliocene (period), fossils of, 250.

Pliohippus, fossil horse, size of, 112;
confusion in name of, 259.

Pliolophus, fossil horse, 258-9.

Pony, great suffering of a, 201.

Portal, learning of, 14.

Pouchet, M., tooth-germs, 274.

Premolar, reasons for use of word,
53; inclination of the, 54.

Processes, alveolar, diseases of, 166.

Protogonia, fossil horse, 203,

Protohippus, fossil horse, 112, 264.

Public Opinion, 287-92.

Pulp, the tooth, 31. -

Pulpal Cavity, relation of, 22.

Purkinjé, discoveries of, 14, 16; cor-
puscles of, 9; cells of, 16.

QUADRUMANA, the, 36, 81, 251.
Quain, Jonas, fifth nerve and oph-
thalmic ganglion, 220.

Ramsey, J., skill of, 104,

Rawux, C., obligation to, 28.

Rénault, Robt., report of, 187-92,

Regimen, 162-164.

Retzius, Prof., discoveries and con-
jectures of, 16, 19, 20, 21.

Revel, M., report of, 197.

Reversion, doctrine of, $0.

Rhinoceros, the, teeth of, 67.

Rhinoceros, the woolly, 251.

Rich, Dr., children’s teeth, 277.

Riders, first nations of, 273.

Rigot, temporary canines, 52.

Robin, C., dog tooth-germs, 27.

Rockwell, E. A., report of, 277.

Roder, Surgeon, on dental cysts. 118.

Roudarnoosky, M., on nerves, 218.

Rousxeau, M., cutting milk teeth, 48.

Ruminants, teeth of, 65; four stom-
achs of, 252.

Ruini, discovery of, 69.

Ryder, J. A., treatise of, 268.

Santry. A. H., report of, 180.

Satterthwaiie, T. E., on corpuscles,
233-4: on tubercles, 255.

Scclidothere, remains of. 108.

Schaaffhau«en, shortened jaws, 99.

Schwann, Dr., researches of, 20.

Seelye Prof., correjation forces, 234,

Selection, natural, 98.

Selection, sexual, 98.

Sewell, W., ental cysts, 122.

Shark, fossil, teeth of, 236.

Simonds, Prof., lever-forceps, 156.

Sinuses, valves, osseous plates, &.,

284

of, 152; gutta-percha as a filling for,
177.
Smith, W., report of, 182-184.
Speculim Oris. use of, 149.
Spencer H.. evolution, 237.
Star, dentinal, 59, 209.
Stone, case of in horse’s jaw, 193.
Strong, Dr., translation by, 274.
Superior Maxillary Nerve, the, 222.
Supernumerary ‘leeth, 127-12) ; 139.
Surmon, H., report of, 177.
Swallowing a Diseased Tooth, death
of a horse from, 187-192.
Swallowing a heathy tooth, 193.
Systemodon, fossil horse, 259, 260-4.

TABLES OF GRINDERS, the, 61.

Teeth, abnormal, cases of beneath
right kidney and near right ear of
a lamb, 116-17; on mastoid process
of temporal bone, posterior part of
sphenoid bone and in testicle, 117;
in ovaries, orbit, palate, tongue,
side of jaw, cheek and neck, 119;
base of ear, 124.

Teeth, absorption roots of, 48, 70-1,
275-6, 288.

Teeth, canine (horses’), description
and probable extinction of, 75-77.
Teeth, canine, use of in different an-
imals, 77-85; made to tear flesh,

271.

Teeth, constant in the same type,
and generally appreciably modified
according to family, 12.

Teeth, continuous growth of, %3,
143; extraction on account of,
178.

Teeth, deciduous, retention of, 129.

Teeth, elephant, unique mode of
cutting and shedding several den-
titions, 274-6 ;

Teeth, elephant (Indian), indications
of age by, 275.

Teeth emanating from osseous sys-
tem, 121.

Teeth, foals’, absorption of roots of,
nop-continuous growth of, scarci-
ty of cement on crowns of, 43;
crowns worn cff by attrition rath-
er than shed, 50; breadth of, 49.

Teeth, fossil birds’, 114.

Teeth, fossilelephant, weight of, 276.

Teeth, fossil horses’ (see ‘* Horses,
fossil,” pe 28h \-

Teeth. fossil horses’ (South and N.
American), 103-19.

Teeth. goats’, gold and silver hues
produced in, 25-6.

Teeth, growing. effect of madder on,
white red and white, 25.

Teeth, horses’, anomalous condition
of, 142,

Teeth, horses’, dimensions of, 71.

size, structure, &c., |
274-6; great quantity cement in. 10.

bly: ‘ae
f it

INDEX.

Teeth, horses’, discovery that they
indicate age, 215.

Teeth, horses’, fillings for, 164.

Teeth, horses’, signs of improve-
ment in, 266, 201.

Teeth, horses’ (Spanish), peculiari-
ties of, 215.

Teeth, horses’, temporary, 47-52;
permanent, 53-74; canimes, 75-93 ;
remnant, 94-114; abnormal, 115—
127; supernumerary, 139; -under
the microscope, 180-125 ; paihol-
ogy of, 136-174 ; dentistry of, 175-
183 ; indicators of age, £03-215.

Teeth, human, changes in, 99.

Teeth, in harmony with gcneral sys-
tem, 11.

Teeth, mules’, telling age by (differ-
‘ing somewhat from horse), 215.

Teeth, readily preserved in a fossil
state, 12.

Teeth, remnant, 94; regarded as
phenomcnons, 94, 101; line of de-
scent, 94; not to be confounded
with supernumerary teeth, $4;
the name. 94 ; easily Jost, 99-109.

Teeth, rudimentary, 99; why good
teachers, 99.

Teeth, cupernumerary. 127-8, 139.

Teeth, three sets of, 128.

Teeth, transplanting of, 26-29.

Teeth, tubes (hollow columns) of, 12.

Teeth, value of to the anatomist, 11.

Teeth, variety and use of, 10, 11.

Teeth, various animals’, Boar, ‘7,
84: Cachalot, 79; Camel, 66, 78;
Cattle, 91-2; Chevrotain, 78, 232;
Coluber Scaber, 121; Copybara
(or Canybara), 10, 233; Dinoceras
mirabilis (fossil) 236; Dugong, 79,
235; Elephant, 77, 274; do. fossil,
244 ; Hippopotamus, 63; Hog, 63;
Hyrax, 260; Iguanodon, 63 ; Lion,
83; Mastodon, 109, 243 ; Megathe-
rium, 107. 242; Muntjac deer, 78,
245; Musk-deer, 78, 245 ; Narwhal,
7G, 246 ; Ornithorhynchus, €0, 247;
Rhinoceros, 67; Ruminants, 65,
252; Shark (fossil), 226; Tapir,
65; Toxodon, 109, 254; Walrus,
v7; Zebra, 52.

Teeth, vascularity of, 22-30; nerves
and circulating vesseis of, 26.

Teeth, wolf, why called remnant, 94.

Tenon, verifies Ruini’s discovery, 69.

Tennyson’s “ gulf of doubt,” 270,

Toes, 97, 112, 265; cause of reduction
in number, 269; form a semicircle
when applied to the ground, 269.

Tomes, C. S., tooth-germs, 57-41;
temporary canines, 52; dentine,
enamel, and cement, 68; attach?
ment of teeth, 72; tushes cf bears,
84-5; evolution, 98-9; no * mark”
in teeth of early fossil horses, 208.

INDEX.

Lope a tooth barricading dis-

se, 139.

Tooth, abnormal, description of, 123.

Tooih, a diseased fossii, 1138-4.

‘Voo.d, a fraccured, 193-9.

Tooth, a prophecy, 202.

"’oota, a whale’s, description of, 79.

Yooth, elephant, in Worth’s Museum
(New York), 275,

Tooth in upper jaw of a bull, 127.

Tooth, vaiure of, 7,8; iridescence
of, 12, 16; no imbherent power of
reparation in, 137.

Tooth Pulp. description of, 31.

Tooth, remnant, vicious inclination
cf a, 104.

Tgoth, swallowing a diseased (fatal),
18-102.

Tooth, swailowing a healthy, 193.

Tooth-Cough, treatment for. 92.

Tooth-Germs, development of, 31-46.

Tooth-Geris, ©o28’. grafting whole

erms, separate enamel organs,
entine caps, &c., ia dogs and

guinea-pigs, those in the latter
animal failing, 27-8.

Tooth-Germs, elephant, 274.

Tooth-Germs, human, transforma-
tions of epithelial and enamel

285

eases of teeth, 138,135; the sinuses,
15%, 153, 161; caries, 164-166 5 dis-
eases of ulveoiar processes, 1b;
parrot-mouth, 167; osteo-sarcoma,
186-7; fractured jaws, 194.

Views of an evoluuonist, 270-2.

WaLuace. A. R., cause of destruc-
tion of ungulata. 111; fossil horses,
112 ; geology, 240.

Walrus, the, mode of figkting of, 77.

Walsh. J. H., age by teeth, xv8.

Wedges, scientific, use of, 271.

West, bone-beds of the, 257.

Wheeler, Capt., report on survey of,
261-2. i

Williams, Prof. W., teething, 91;
remnant teeth, 104, 105; dental
cysts, 125-127; caries, 169-171.

Williams. W., necrosis, 246.

Winter, J. H., use of tushes, 85.

Wolf-teeth, why a good generic
name, 94.

Woodward, J. J., tooth pulp, 31;
histology, 241.

Woolly Rhinoceros, (fossil), 251.

Works, general, 4.

Works, special, 4, 290.

_Wortman, J. L.. on fossil horses,

erms, dentine bulbs, caps, &c., | ° SCO)
| Wyman, Prof. discovery of, 81.

in, from 7th to 39th week, 46.
Tooth-Tumor, unusual case of, 196.
Tooth and Bone, analogy of, 23.

Toxodon, remains of, 109; descrip- |

tion of, 254.
Trepnine, the, 254.
Trephining Sinuses, 157-161.

Trigeminus Nerve (in the horse), de-

scription of, 216-226.

Tripier, M., resection of nerves, 217.

Trocar, the, 255.

Tushes. fighting with, in various
animals, 77-85,

Tu-hes. horses’, practically useless,
75; different from other teeth. 75;
distances from incisors and grind-
ers, 75, 75; shape and dimensions
of, 76; curvature of roots, 76.

Tushes, removal of, 155.

Tushes, size of in Orohippus, 97.

Tusks, elephant. fighting with, 77;
varying curvatures, weight, length,
&c., of. 276.

Tuttle, R. M., on evolution, 270-2.

VARNELL, G., opinion of, 102; dis-

257-269: discovery of. 260.

| Yates, L. G., fossil elephant teeth,

276.

Youatt, W., sugar as food, 30;
tooth-germs, 44, 45; infundibula
of grinders. 58; description of
lower jaw, 62; use of tushes, 84;
teething, 85, 86; lampas, 90, 91;
cropping horses’ ears, 103; rem-
nant teeth, 105; food, 162-164;
diseases of teeth, 172, 173; frac-
tured jaws, 196-198; ‘mark’ of
central nippers, 205; difficulties
of judging age, 207; bishoping,
210; trad tricks, 212, 214; crib-
biting, 212, 213 ; indications of age
independent of teeth, 214; fifth
pair of nerves, 216-225; czecum,
230: colon, 232; membrana nicti-
tans, 244: solipeds. 253.

Youmans, E. L., evolution, 287.

ZEBRA, temporary canine teeth of,

52;
Zovdlogy, definition of, 256.

ee fy"

iets Ear e
oF 18 pier

*

PUB OE UNTON,

Horses’ TreTH.—Such is the title of a work we have just
read with considerable interest, because it embraces much that
is instructive and useful. Designed as the publication is to
give a synopsis of the fundamental principles of dental science,
it has a defect attributable to the author’s lack of practical
experience in the specialty of which he treats. * * * The
chapter on canine teeth contains much of interest, and fully
sustains the theory that horses suffer from febrile irritations,
as the result of interrupted dentition, and that the free use of
the lance is as serviceable as when used on an obstructed eye-
tooth of achild. The disease known as lampas, which is often
accompained by a distressing cough, and which so seriously
interferes with feeding, is shown to be due to the same cause
and to require the same remedy. To state that caries most
frequently proceeds from inflammation beginning in the pulp-
cavity, or that caries of the roots is the result of inflammation
of the alveolo-dental periosteum, is certainly far from the ex-
perience of the practical dentist; but, notwithstanding these
defects, there is much of value in this (the eighth chapter) as
well as the succeeding chapters on the dentistry of the teeth,
their indications of age, their nerves, && * * *—C. WN.
Pierce in ‘‘ Dental Cosmos.”

“‘HorsEs’ TEETH,” by Wm. H. Clarke of New York, is a
neat and handsomely bound volume, containing selections from
the very best authors, with appropriate additions by the
author, makin& a book that is invaluable to veterinary sur-
geons, and of great practical benefit to dentists, and should be

288 PUBLIC OPINION.

studied by every person who treats the tecth. The author
treats of the teeth from the time of the formation of the germ
to their full development, and gives their pathology and den-
tistry also. A vocabulary of the technical terms used forms a
valuable addition.—Denta! News. ‘

THis work is undoubtedly in advance of anything hereto-
fore published on the subject in this country. * * * When
the author says that “probably the temporary teeth are
absorbed by the permanent,” he displays the folly of attempt-
ing to write on a sudject that one does not understand.* Still
the work is useful and will probably aid in the elevation of
veterinary surgery. —W-ssourt Dental Journal.

Tus book is ina great measure a compilation from works
on dentistry, anatomy, physiology, microscopy and veterinary
surgery, as they relate to the development, structure and care
of the teeth of horses. As we are a believer in horse dentistry,
we have looked over the work with much pleasure and no
inconsiderable profit.— Dental Adveriiser.

TuIs book is a venture in the field of veterinary science
which we hope to see more frequently imitated. It is mainly
a compilation, admirably arranged, and prepared with great
thoroughness of detail. The compiled matter is well selected
and condensed, much of it being rewritten. It contains much
besides the matter pertaining to horses’ teeth, the teeth of
many other animais being described and compared with those
of the horse; in fact, the work might be entitled “Teeth ”
instead of.“ Horses’ Teeth.” It gives a history of the evolu-
tion of the horse from early geological periods, the wolf-teeth,
which the author has named ‘Remnant Teeth,” being traced
back to the Eocene period, when they were functionally
developed. ‘This fact throws light on what has been a mys-
tery, and the author appears to have made a discovery.

The work, as a whole, is very commendable, and we feel

* See pages 48 and 50. A few changes have been made and some fresh
matter added. But I will venture to ask the editor of the Journal what
becomes of the voots of a temporary tooth when the shell of its crown when
shed is sometimes not more than the sixteenth of an inch in thickness?
What becemes of the roots of elephant teeth? (See pages 274-3-6.)

PUBLIC OPINION. ~ 289

sure it will find a place in the library of all interested in a
thoroughly practical as well as scientific knowledge of horses’
teeth, and will be found especially valuable both to the student
and practitioner of comparative medicine and surgery.—Jour-
nai of Comparative Medicine and Surgery.

THE work consists mainly of quotations from standard
writers. It is very interesting and instructive reading, and is
fully worth the small sum it costs. The author deserves credit
for his labor in collecting information from so many separate
- sources, and presenting it in so small a compass and so readable
aform. However, there are errors in the vocabulary that ought
to be corrected.— Veterinary Gazette.

IT possesses the merit of presenting in a condensed form, for
the study of the veterinary surgeon, the anatomy, pathology,
_ and reparative surgery of horses’ teeth, and to him it will save
much labor and furnish a ready reference, and hence be an
efficient aid. * * *—WMedical Gazette.

* * * THE work contains an immense amount of useful
information, and as it fills an unoccupied field, ought to be
successful.— Medical Record.

WE understand this book is having a rapid sale among
horsemen. Hereafter we suppose the title H. D. D. will be-
come common. How nicely Mr. Clarke telis us of the cutting
and shedding of the temporary and permaneni dentitions, In
the future we expect that greater attention will be given to the
teeth.— North American Journal of Homeopathy.

Horsss’ TEETH.—Owners of all classes of horses should be
in possession of a remarkably useful work entitled ‘“ Horses’
Teeth,” by Wm. H. Clarke. The work is based on the best
authorities on odontology and veterinary science, and arranged
in an easy, comprehensive form. With a view of rendering
technical terms readily understood, a vocabulary of the medical
and technical terms is attached. Dental science, as hitherto
expounded, has never afforded horse owners the instruction it
professes to aim at. The trouble has been the use of technical
phrases. Mr, Clarke, alive to the necessity of giving to the
public a popular treatise, has presented a work which must

290 PUBLIC OPINION.
find its way in all circles, and, above all, reach the understand-
ing of the average reader.—Turf, Field and Farm.

Tuts work deals with horses’ teeth in a very complete man-
ner, and will doubtless be found of great value by students of
veterinary science. It isa compilation, but Mr. Clarke has done
his work in a careful manner. * * * A study of this work
cannot fail to be of value to all who are interested in the
horse.—London (Eng.) Live Stock Journal.

THE book is compiled from the best authorities—Rural
New Yorker.

Horsts’ TEETH.—We have received from Mr. W. H. Clarke
a duodecimo volume containing a compilation of everything
valuable that has been written by the best known odontologists,
* *% # The so-called ‘“ wolf-teeth ” are traced to the horse
which existed previous to the pliocene period. Mr. Clarke
calls them ‘‘remnant” teeth. * * * ‘The work isa valuable
addition to veterinary science.— The Country Gentleman.

It is a venture in the field of veterinary science, and, though
in general a compilation, will be found of great practical service,
and in its present form a new thing. It will be of use especially
to horsemen and farmers.—Massachusetts Ploughman.

Tus work is mainly compiled, but the selections evince care,
judgment, research, and discrimination. It will prove valuable
to the veterinary student and practitioner.—Pen and Plow.

Hap this work been issued prior to Huxiey’s “Crayfish” or
Comte’s “ Sight” it would have been deemed too special. The
subject is scientifically treated, with a decided tendency toward
the practical. * * *.—Syracuse Standard.

Horsss’ TEETH.—* * * Mr. Clarke devotes considerable
space to descriptions of the different classes of teeth, * * *
Although there is a great deal of technical language in the
work the copious vocabulary at its close renders it practical for
those who wish to learn about the structure and diseases of the
teeth, and the method of treating them under various circum-
stances. Many instances are quoted from good authorities in
which horses have been treated for diseases of the jaw, and the

PUBLIC OPINION. 291

methods by means of which they were cured are carefully set
forth. We present some extracts from the chapter on the teeth
as indicators of age. (See pp. 204-5.) The treatment of this
subject is only an example of the fullness and accuracy of the
entire work.— Utica Herald,

Mr. W. H. CLARKz’s “ Horses’ Teeth” is a complete and
interesting treatise which may be accepted at once as both a
useful manual of equine dentistry and an agreeable study of
certain aspects of comparative zoology. Every possible de-
formity or peculiarity observable in the teeth of the horse, as
well as every roguery practiced on them by dishonest dealers
is fully handled, and a succinct account is given of all the
maladies of the teeth themselves, and of other organs with
which the teeth have a functional relation —New York Herald.

THE treatise on horses’ teeth by William H. Clarke, a metro-
politan journalist, has already attracted wide attention, and is
an invaluable work in its way. Great care and much labor
have been bestowed in its preparation, and the book supplies a
want that has long been felt by horsemen, farmers and the
student and practitioner of comparative medicine and surgery.
—New York Graphic.

THE title so fully describes the scope of the volume that
little need be added except criticism. The author is frank
enough to admit professional inexperience, but has made the
topic of the work a matter of careful investigation for a year.
He has wisely deferred to the opinions of naturalists and veter-
inary surgeons, and quotes liberally from their works in every
chapter, thus supplying a cyclopedic stock of information bear-
ing directly on horses’ teeth in health and disease, which is
very convenient for those who keep or raise horses, and the
average veterinary surgeon.—Phrenologicul Journal.

THE thoroughness of detail with which every point relating
to the subject of this work is treated will impress every one
with its reliability and value. It is undoubtedly true that
much suffering, disease and death have resulted from ignor-
ance of what i$ herein given, and that much unintentional
cruelty to horses may be prevented by studying this volame.

292 PUBLIC OPINION.

Though the title implies that the work is confined exclusively
to the teeth of horses, it is not so; the teeth of other animals
claim nearly as much attention as those of the horse. The
tueory of evolution is introduced, the history of the horse being
traced from the Eocene period, when the wolf or “remnant”
teeth were functionally developed. The book will be prized by
all who seek the welfare and happiness not only of the human
race, but of all sentient beings.—Bunner of Light.

WE all know that horses suffer with their teeth, and the
work gives full instructions as to their care. * * * The
author is an evolutionist, and has devoted much study to fossil
horses.—Wew Orleans Times.

PRACTICAL Booxs.—“ Horses’ Teeth,” is a valuable treatise
that ought to be in the possession of horsemen, farmers, and
veterinarians. * * *,—Pitisburg Commercial Gazette.

Dr. C, F. HoEING (Jersey City Hights, N. J.) says: “ After
a careful reading of your book, ‘ Horses’ Teeth,’ I wish to say
that it appears to me to be an able compilation of scientific
fasts, and a basis for further investigation of horse dentistry
by the profession; at the same time containing valuable in-
formation for intelligent horsemen and farmers, as well as
naturalists generally. I miss only very valuable information
to be found in numerous German books,”

Dr. J. M. Hearp, 205 Lexington Ave., New York, says:
“The book is full of valuable information ; in fact, one would
search a sinele library in vain to obtain it. None bat those
who have performed similar work can appreciate the immense
amount of labor expended in its preparation. No student or
practitioner can afford to be without it.”

Dr. B S&S. Brewster of Norwich, Conn., says: ‘“‘I have been
an advocate of horse dentistry for thirty years, even arguing
against veterinary surgeons. Thank God, light has come at
last.”

SSS

hy )

—-
—— —S=
a

2-Year-Old, Lower Jaw; drawn from Nature.

8-Year-Old, Lower Jaw; drawn from Nature.

‘ i

4-Year-Old, Lower Jaw; drawn from Nature.

——
———

. . N : L3WN i? ANS
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6-Year-Old, Lower Jaw; drawn from Nature.

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The Mark, dissected as it c, The Dentinal star, somes
were, (See page 58.) times mistaken for the
mark, (See page 209.)

12 years, Lower Jaw. Change in shape is now clearly defined,
The respective pairs (centrals, dividers, corners) assume in turn
(from 12 years till old age) various shapes—semi-square, rounded,
triangular, wedge-shaped, etc.

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15 years, Upper Jaw.

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23 years, Upper Jaw.

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25 years,

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A Parrot-Mouth (lower jaw). The ten lines represent ten
years’ growth. The marks, having never been worn, represent
a 6-year-vld. The horse is therefore 16 years old. (This cut,
as well as many of the preceding, is from Brandt's “Age of
Horses.”)

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MANUFACTURERS AND IMPORTERS OF

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Price List of Veterinary Dental Instruments
Illustrated in this book.

Plate I. Fig.1. Adjustable Tooth File; in handle to unscrew, $4.00

ee OES a a «dn stiff handle-=a0e.- 3.00

House’s “ “« in handle to unscrew, 4.00*

House’s ue 4 in stiff handle........ 3.00”
“ ‘ -$.-Prof. Goine’s Zooth Chisel ........-seaceeeeee 17.50
ae ‘ 4. French Model “ (4. acre osene tem eeeeetS 14.00
a «« 5. Tooth Mallet, lead filled, not rebounding...... 2.50
“ « <6, French’ Model Looth Saw c. 000 «~<scic)s eee 3.50
« ** 7, Narrow Tooth Chisel, length 5 inches .......-. 1.26

Plate I. Fig. 8. Narrow Tooth Gouge, length 6inches......... $1.60
oe « 9. Tooth Rasp guarded ; in stiff handle........... 3.00”
“ ae s in handle tounsgrew.... 3.75*
“ “= plains ii stiff handle .......cseavs, etl
“ « plain; in handle to umscrew....... 2.50*

- “10. Extra Blade for Adjustable Tooth Tile.......... 0.40
Extra Blade for House’s ue ON aide Skee 0.40*
Plate II, ‘11, Heavy Tooth Forceps, length 15 inches........ 5.50
-” “ 12. Prof. Going’s Tooth Forceps with closing screw
and crank handle........... Scent onidatsass 25,00 °
$4 ‘© 13. House’s Tooth Cutting Forceps,
oo *¢ 14, House’s Tooth Pulling Forceps, 28.00
one set of removable handles to both we
“¢ * 15. Wolf Tooth Forceps, length 9 inches........... 3.50
4 * 16. Wide Tooth Chisel, length 10 inches............ 2.00
“ “ bi 6) ha Et Ae ae asecunte 3.00
Plate ITI. “17. Tooth Cutting Forceps, French model........ 25.00
ie ae f < BIOMGE BS. . 9:5. 60' dv gae'ae 32.00
- rig <: su “a French model ......... 20.50
" «« 20. House’s Tooth Cutting ForcepS.........eeeeees 6.50
see Leaf = - de Re TY Sha atts wows 6.50
sc ¢ 22 ss S os a Sieh ee Pieri Pee 6.50
- © 23 as = “ Pre ce aaen a eee ee 6.50
es “« 24. Narrow Tooth Gouge, with steel head.......... 2.00
Plate IV. ‘ 25. Bow Tooth Saw, with two blades............... 6.00
ee « 26. Tooth Key, with hooks of assorted sizes....... 35.00
2 Ser. edt SL OOUIN Sa Wp cee bin go eos ob ce Geied eye age ot 1.50
“ Ot linia ae COC CWE = pc ed «nis ck ane wasewecyccnees 12.50
a OOS Mind sOETUled WOOUL SAW s ...0ds oda: cess tenses 1.75
« 30. Narrow Tooth Chisel, length 6 inches .......... 1.25
os * 31. Hurlburt’s Gum Knife and Tooth Pick ........ 2.00

Our Alphabetical Register of Veterinary In-
struments of 90 Pages and containing about 325
engravings, mailed free upon receipt of four Cents
for Postage, to all who mention this book.

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