for a great length, or entirely round the bone. These are called respectively the Haversian, the periosteal, and the medullary lamellæ. The latter two, or circumferential, lamellæ are only conspicuous in bones of full growth. Between the lamellæ are numerous little cavities seen only in dried bone, which are elongated or flattened, and they extend comformably with the direction of the lamella. These minute spaces are named lacunæ. The distance from each lacuna to the neighbouring lacunæ is seldom more thanth of an inch. Moreover, each lacuna is connected with its neighbours by numerous minute channels or canaliculi, which pursue a somewhat wavy course. The canaliculi are usually not separated from one another by a greater distance than 50th of an inch.

In the living condition a lacuna contains the remnant of the formative osteoblast, and processes from this occupy the canaliculi.

Other structures which are to be seen with the aid of the microscope are the "perforating fibres of Sharpey." They are to be found by pulling asunder the sections of lamellæ of a decalcified bone. They are also very numerous in the cementum of teeth. Sharpey's fibres seemed to have no physiological significance; they may be regarded as merely a modification of the mechanical structure of the tissue. These fibres probably consist of bundles of calcified connective tissue.

The formation of osseous tissue takes place in the same way in the cancellated texture and in the compact tissue.

There are two modes of ossification, known as intra-membranous and intra-cartilaginous. Most of the bones of the skull and face, and the cementum of teeth are examples of the former, while the long bones are developed in cartilage.

Periosteum covers all bone, except at the articular surfaces where the sub-articular cartilage is in contact with the bone. Periosteum consists of fibrous tissue, bloodvessels, and nerves. Upon the surface the fibrous tissue is somewhat dense, whereas, deeply, it is open and reticulate, and bundles of fibres run into the bone. The cells in the closer part of the structure are similar to connective-tissue corpuscles, but in the inner reticulate meshes they are large and numerous, and form the osteoblasts, which, for the most part, cover the surface of the bone. The blood-vessels ramify in the periosteum and then enter the bone, carrying with them a process of the periosteum into the Haversian canals. In this way it may be regarded as the nutrient membrane, and, as recently mentioned, the source of the periosteal lamellæ and of Sharpey's fibres.

Dental Surgery and Medicine.

A

CLEFT AND PERFORATE PALATE.

paper read before the Students' Society of the Dental Hospital of London, January 17th, 1881.

a paper

By W. A. TURNER, Esq.

MR. PRESIDENT AND GENTLEMEN.-When asked to read before this Society, I must confess that it was not without some difficulty I decided upon a subject, for it seemed impossible to find one of any practical value, which had not been treated of in some previous paper.

That which I have chosen seems, however, so far to have been omitted, and as it is a deficiency which frequently falls under our notice, and which we are called upon to make good, a few moments spent in considering the circumstances which may give rise to them, and the treatment adopted to make good these defects, may not be illspent.

I propose first to consider the deformity as a result of imperfect development, or " congenital cleft," as it is usually termed. We get every variety of the extent of defect; from a mere bifurcation of the uvula, to a complete chasm extending through both hard and soft palates; often with great displacement of the incisive bones, and associated with double or single fissure in the lip, the nasal septum often being greatly bent to one side. In some cases the intermaxillary bones have been said to be absent altogether, but I believe these examples are rare. It is a very exceptional thing to find the cleft extending through the median line in the front part, between the premaxillary bones. The course of what in foetal life is the suture between the incisive bone and true maxilla is generally followed, and the cleft in the lip is consequently not median; it is therefore not an exact representation of the condition found in the hare, where it is always single and central.

Although the anatomy of the incisive or intermaxillary bones has been described in outline by some of the ancient anatomists, Galen, Nasmyth, and others, yet little importance seems to have been attached to them by these authors. Goethe, in 1780, speaks a little more on the subject, but even so recently as the early part of the late Sir William Fergusson's time, the usual practice was to snip them off when they were

so malplaced as to interfere with the closure of the fissures in the lips, and with them, of course, went the incisor teeth. Since then, however, their importance has been more fully appreciated, and they are not sacrificed with the same freedom, they are often reduced to a tolerably good position in cases where not too rigidly fixed, by means of pressure brought to bear on them by the use of Hainsby's splint.

But even with the best intentions, it is not always possible to preserve the incisive bones; thus in a case which was lately treated at Middlesex Hospital, these were represented by what appeared to be a nodular pedunculated fibrous outgrowth, attached to the outer extremity of the nasal septum, with a fissure on either side through the lip. It was found impossible to reduce the mass to anything like its normal position so as to close the lip over it, there was therefore nothing left but to remove it. This was accordingly done by Mr. Hulke, who kindly gave me the mass for the purpose of making a section, which, as you can see, presents a splendid opportunity for examining the condition of the parts under these circumstances. The child was four months old, the central incisors are well seen in the section, calcified through nearly the whole of their crowns, although ossification in those portions which represent the incisive bones and forming a casing round the teeth, has scarcely gone far enough to form true bone, being easily cut through by the knife.

According to Salter, a perforation may exist in the hard palate alone, the fore-and-aft parts being perfect, as a result of congenital defect. When the alveolar portion only is cleft, as sometimes happens, it is seldom we find any deficiency in the lip; on the other hand, the lip is often defective when there is no sign of imperfection in the palate.

To understand how these conditions are arrived at, it is necessary we should be acquainted with the mode of development, and the relation of these several parts with one another at a very early stage of their formation, when the first traces of ossification appear and the opportunity is afforded of recognising the elements of which they are composed. At this time, which in the human subject is about the middle of the second month of fœtal life, we find the nasal and oral cavities undivided, the lateral processes being but very rudimentary, and the four bony centres which by their coalescence are ultimately to form the roof of the mouth are widely separate. As development goes on, these gradually increase in size, until, under normal circumstances, the incisor bones on either side become united with the true maxilla of that side, thus forming one bone, which is con

nected to that of the opposite side by fibrous tissue, the whole being completed by the time of birth. But in these cases where we find the process to have been defective in the front of the mouth, we see it is failure of bony union, whereas in the palate processes of the true maxillæ it is of course failure in the median line, so we often get a perfect Y-shaped cleft. It is easy to see why the two premaxillaries do not fail to become connected to one another, as their two centres are so close; but the distance between them and the rest of the palate is very considerable, and requires a much longer period to perfect it, and the same thing applies with greater force to the velum.

Keeping, then, the mode of the development of these parts in view, we can easily understand how anything which may tend to retard or in any way disturb the parts during these early stages would bring about the conditions we are called upon to remedy. But why these particular parts are so affected, whilst other structures of the same body are perfectly and normally developed, it is not easy to see, nor can we do more than speculate upon the causes which produce it. There are many defects which are peculiar alike to parent and child, and of which we can say without the slightest doubt that they are hereditary, but we cannot do so with regard to congenital cleft palate, for we constantly find that parents so affected have children who show not the slightest sign of the deformity, and again, though both parents may be perfectly free and no trace of it in the family before, yet one or two of the children of these parents may present the defect in its most extreme form. A case of this latter kind occurred in a family, one of which attended the hospital just before Christmas, and as the case was entrusted to me I was able to inquire fully into his family history which showed the following interesting facts:

R. C-, aged 22, a miner, of Grosmont, Yorkshire, a hearty-looking and well-built young man, who had never shown the slightest signs of illness. Father and mother living, quite healthy; two sisters, both living. Not the slightest mark of any deformity in either parent, but all three children are affected; one sister had harelip, no cleft in palate, the other sister presented the same conditions as patient, viz. single harelip, and cleft extending from about the middle of the hard palate backwards through the soft. The fissures in the lips had, of course, been closed when they were infants. To the treatment of these cases I shall again refer. The deficiency in the palate was in each case restored by means of an obturator.

Some writers seem to think that civilisation may tend to

produce these conditions, yet one fails to see in what way it can act. We all know well its influence on the development of the dental organs and those portions of the jaw subservient to them, and also upon the features in general, and at first sight it would seem reasonable to suppose that it may have some part in producing imperfect palates as well. But the changes wrought in the shape, size, &c., of the teeth and associated parts, are produced gradually by hereditary transmission, and are materially influenced by "sexual selection," &c., factors which seem to play no part in the causation of congenital cleft palate.

It would seem, however, that certain hygienic conditions may tend to produce these defects of the palate. Thus, it is interesting to find that a considerable proportion of the young lions born in the Zoological Gardens, Regent's Park, have defective palates, and consequently die young, but that this does not occur with the young of those confined in other places. Whether it ever occurs in the more savage races of mankind I cannot say, but we find records of various devices designed to remedy the evils arising from this defect amongst the most ancient surgical literature of civilised nations. It is not, however, until quite recently that any attempts seem to have been made to restore the deformity by surgical ope

ration.

The first cases are reported to have been performed by Roux, a French surgeon, in 1819. He is said to have performed it on a medical student, and after that to have treated successfully a number of cases; but I believe his operations were confined to the soft palate, the hard, when deficient, being made good by an obturator. The operation introduced by him does not, however, seem to have been by any means a certain one, the tension of the velum muscles often breaking the stitches before union of the edges of the fissure had been effected. To remove this cause of failure, transverse incisions were made on either side of the cleft by Liston and others, but it was not until the introduction of myotomy on a rational basis, by the late Sir William Fergusson, that this difficulty was surmounted. Since that time the operation has been extensively practised, and is generally a surgical success, though the result, as regards improvement of the patient's articulation, is not always what might have been expected.

In deciding upon this operation there are two points which may serve to help the prognosis. First, the age of the patient to be operated on, and, secondly, his general condition.

With reference to the age best suited many differences of opinion exist; thus, in some works on general surgery, you