The degree of D.D.S. was conferred on the following graduates by S. D. Gross, M.D., president of the board of trustees :

J. Frank Adams, L. D. S., Canada.; Theodore Balderson, Pennsylvania; Franklin H Benner, Pennsylvania; William F. L. Biddell, Pennsylvania; Albert C. Blind, Pennsylvania; Albert P. Brubaker, A. M.. M. D., Pennsylvania; Anna Castner, Germany; William T. Chambers, Ohio; Louise M. Diederich, Germany; Henry Fraser, West Indies; Benjamin H. Goodsell, New York; C. Fred Gould, Iowa; William E. Holland, Pennsylvania; Harry G. Keeler, New Jersey; James H. Keisel, Pennsylvania; Wilbur A. Kessler, Pennsylvania; Henry G. Kemper, Pennsylvania; Lucius A. Kelsey, New York, John P. Libhart, Pehnsylvania ; David Souper Lyon, New Jersey; Woodward R. McCloskey, Pennsylvania; J. Eugene Mohr, Pennsylvania; A. Milton Musser, Jr., Utah; Frank W. Monroe, Pennsylvania; Johan Nawroth, Germany; Olga Neymann, B. L., New York; Nettie Ogilvie, West Indies; Walter J. Phillips, Iowa; J. Thomp. Price, Ohio; Charles S. Potts, Pennsylvania; Levi Pownall, Pennsylvania; J. Clark Rankin, Pennsylvania; Edwin P. Robinson, New York; James S. Rutter, Pennsylvania; J. Herbert Sahler, Pennsylvania; J. G. Santana, Cuba; Maria M. Schneegans, Germany; Henry Charles Smale, L. D. S., England; Norberto E. Soto, U. S. of Colombia; George Adams Swann, Canada; Charles Swap, Missouri; James Tait, Pennsylvania; Oliver H. Taft, New York; Thomas W. Thomas, Pennsylvania; James E. Weirick, Pennsylvania; Park W. Wicks, New York; John J. Whaley, Canada; Olga Wernickie, Pennsylvania.

PHILADELPHIA DENTAL College.

The Twenty-Third Annual Commencement of the Philadelphia Dental College was held at the Academy of Music, February 26th, 1885, at 8 P. M.

The number of students of the session was one hundred and forty-six.

The address to the graduates was delivered by Prof. T. C. Stellwagen, M. D., D. D. S.; and the valedictory delivered by J. Collord White, D. D. S.

Hon. James Pollock, president of the board of trustees, conferred the degree of D. D. S., on the following graduates:

Henry Behrens, Jr., New York; Elsworth E. Bentzel, Pennsylvania; Bernard B. Bray, Texas; Cornelia Brown, Pennsylvania;

Gordon Brown, Missouri; Wm. A. Bryant, M. D., California: Harry H, Burchard, Pennsylvania; Irwin G. Burton, Delaware; Alonzo H. Carlile, Delaware; George W. Cochran, Ohio; Charles W. Collins, New York; W. R. G. Downes, Canada; James R. F. Fitzpatrick, Massachusetts; Edward H. Forrester, New York; Arthur B. Freeman, M. D., Illinois; Clayton G. Gable, Pennsylvania; Henry L. Gilmour, Jr., New Jersey; Jennie R. Gould. Pennsylvania; J. A. Greenawalt, Pennsylvania; A. C. Manfred Hafstrom, Sweden; Glyndeur Hickman, Pennsylvania; W. H. J. Holman, Pennsylvania; Charles I. Huntington, New York; Ernest J. Husband, Canada; Otto E. Englis, New Jersey; Adolph Jackson, California; William B. Knox, New York; A. R. Markel, Pennsylvania; Grant Mitchell, Ohio; William H. Newton, Massachusetts; Charles C. Patten, Maine; Will S. Payson, Maine; Frank A. Post, New York; Hugh G. Pullen, Canada; Walter J. Quinlan, Canada; Charles H. Riggs, Florida; Whitman C. Robbins, South Africa; John P. Ruf, New York; A. G. Smith, Ohio; F. W. Smith, Maine; Charles E. Stephenson, Pennsylvania; Lee K. Stewart, Illinois, C. E. Thompson, New York; Curtis B. Tiley, Connecticut; Henry T. Walker, Texas; J. Collord White, Pennsylvania ; Seymour M. White, Pennsylvania; W. H. White, Canada; Harman Yerkes, Pennsylvania; M. Pastor U. Zegers, Chili.

BOOKS AND PAMPHLETS.

PEARSON'S DENTAL APPOINTMENT BOOK. R. I. Pearson & Co., publishers, Kansas City, Mo.; 1886.

The neatest thing of the kind ever offered to the dental profession, can be carried in the vest pocket, arranged for appointments for eight hours of every working day in the year. Blank pages in back for memoranda. By using this little book, you have your appointments always with you. Bound in red Russia leather, with With your name neatly printed

pencil attached. Price, 50 cents. in gold on cover, 75 cents.

THE

Dental Practitioner.

A MONTHLY JOURNAL OF DENTAL SCIENCE.

Read before the "Garretsonian Society" of the Philadelphia Dental
College, Dec. 22d, 1885.

BY ARTHUR B. FREEMAN, M.D., D.D.S., OF CHICAGO, ILL.

The subject I have chosen to present to you this evening is one in which I have been much interested myself; one which is most intimately associated with the fundamental principles of our specialty; one which is but vaguely understood by the masses of the profession, and one, too, regarding which there is much difference of opinion and some mysticism-namely, the "Embryology of the Human Maxillæ and Teeth."

I shall not attempt to be original, or reconcile the variance of opinion entertained by investigators of the subject-nor am I competent to do so if I would-but simply to review and present it to you from the standpoint of some of our eminent histologists and physiologists, whose theories seem to be coming to be more generally entertained and taught.

It has been a broad field of research in recent years and much has been written. I shall, however, in this brief essay necessarily omit as many confusing technicalities and minor details as possible with a proper comprehension of the topic.

In the early development of the human embryo, after the union of the nuclei and protoplasm of the paternal and maternal cells, there is an indefinite proliferation of new cells which, undergoing changes, recede toward the periphery of the ovum, taking the name of the blastoderm, or blastodermic membrane.

1

t

This membrane again speedily undergoes cellular change and splits into three distinct layers, from which all the complex structures of the body have been traced in their development, and from without inward have received the name of epiblastic, messoblastic and hypoblastic membranes.

The epiblastic or outer membrane is destined by a wonderful transformation to develop the epidermis, hair, nails, enamel of the teeth and nervous system; the messoblastic or intermediate membrane develops the dermis-osseous, muscular and circulatory systems and the connective tissue, while from the hypoblastic membrane internally the alimentary canal and glandular appendages of digestion have their origin.

Early in this development the embryo elongates and two oblong ridges, the dorsal lamina, make their appearance, inclosing between them the rudimentary spinal cord.

From this time on the cephalic flexure is developed slightly in advance of the caudal extremity, and becomes somewhat expanded.

Upon the anterior surface of this expansion and extending forward from the cervical lamina of either side-which are simply a prolongation upward of the dorsal lamina-several comparatively broad arches are developed, the superior or frontal arch, and the inferior or visceral arches.

At about the eighteenth day of embryonal existence there are to be seen sprouting from a single point on the superior or first visceral arch, four processes; two of these, one on either side, pass outward, downward and forward to meet and unite at a point which will represent the future symphysis menti of the inferior maxilla; the other pair of processes pass, one on either side, upward, outward and forward, representing the superior maxillary halves; and simultaneous with their growth a pair of arms sprout downward from the centre of the frontal arch to occupy the intervening space and represent the incisive or intermaxillary bones.

The edges of these incisive processes unite with each other and with the maxillary halves of either side at about the twenty-eighth day, representing the superior maxilla as a whole, when the embryo is only three-fourths of an inch in length.

It is worthy of our notice just here that a failure of union of the two incisive processes with each other at this early period is the cause of congenital cleft-palate, and in failure of the union of either intermaxillary process with its corresponding maxillary fellow we

have hare-lip, being single or double according as union fails on one or both sides.

To again return to the inferior maxilla at the twenty-eighth day: A round, whitish, gelatino-cartilaginous body may be seen to be forming, imbedded in the centre of the process at the median line; growing backward on either side, this body becomes fully developed at or about the sixth week.

This is Meckel's cartilage, and receives its name from a celebrated German anatomist who first discovered and described it in 1820.

It is composed of an auditory portion, from which is developed the small bones of the middle ear, the malleus, incus and stapes, which remain permanent throughout life; also a maxillary portion with a temporary function of supporting these delicate tissues for a time, being absorbed between the fourth and sixth months, or after calcification has sufficiently progressed to dispense with the organ.

Now, that we may better understand the minute development of the teeth, let us briefly recall the anatomy of the skin and mucous membrane, the two being analogous, except the latter is more attenuated and in the embryo is in a state of formation.

Histologists divide the skin into two grand divisions—the epidermis, outer or scarf skin, and beneath it the dermis or true skin.

The epidermis is again divided into two subdivisions; the superficial layer is called the stratum, corneum or horny layer and is composed of a series of dry, flattened, non-nucleated, non-nourished, epidermal plates which overlap one another.

The deeper layer of the epidermis is relatively the thicker and is known as the stratum or rete mucosum, and is made up of many layers of nucleated cells, placed one above another; the most superficial are somewhat flattened, beneath which are two or three rows of larger polyhedral cells, and again underneath these are two other layers, the prickle cells, which are of the same general form as the preceding, but differing from them in having spoke-like prolongations extending from their many sides to the adjacent cells.

Beneath all these is still another important tier of columnar epithelial cells resting upon the basement membrane, with their long axes at right angles with it.

The cells of the "rete" are surrounded by protoplasm and supplied with nutritive material by osmosis from the capillary vessels of the dermis beneath.

The dermis is composed of two layers, the pars-papillaris and