Twenty-fourth Day. The specimens of the twenty-fourth day show complete and true ossific union. The Haversian canals are re-established throughout the divided portion, and much of the redundant exudation has been absorbed. From these microscopic studies we may make several deductions. First. As to the existence of the exudation from the parts surrounding the fracture, which as early as the sixth or eighth day is well developed, and covered with a smooth shining surface, the new periosteum. Second. The destruction of the old periosteum at the point of injury. Third. It seems to me to be demonstrated, that the exuded elements have an individuality peculiar to themselves; that this protoplasmic or germinal material is placed in such relations to the new and very vascular periosteum that osteoblasts are rapidly evolved, which arrange themselves in relation to each other and the previously formed material in accord with a fixed law. Professor Ercolani arrived at a somewhat similar deduction when he said, "that this new periosteum which is formed impresses its osteo-genetic action on the exuded cellular elements, and it is by this that they are transformed into bone." Two conditions are indispensable for the development of the external callus and its ossific function: First, there should be an exudation of plastic or germinal material; and second, that this should be covered by or in close relation with a newlydeveloped periosteum, and either of these conditions failing the repair processes are not perfected. This condition of the transformation of the soft neoplasm into osseous substance shows us, as referred to when describing fissures of bone, why the consolidation of fissures does not take place, and this in turn teaches the importance of recognizing these two fundamental factors in the formation of the callus. I call attention to two specimens from the buffalo, as illustrating, in a marked degree, these deductions. The first is the spinous process of a vertebra showing gunshot injury. The bullet was flattened against the bone, and is retained in its position by outgrowing spicula of new bone. To the very exVOL. XXXI.-59 tremity of the process, twelve inches in length, the bone is slightly roughened, showing that a periostitis supervened the injury, but accompanied by a very limited exudation of neoplastic elements. The second is a compound comminuted gunshot fracture of the scapula near its neck from the same animal. The fragments are very firmly united by an immense osteo-plastic new growth, increasing the weight of the bone perhaps one-third. Irritated periosteum and neoplastic material were both found in ample facturage for the new development. The consolidation of fissures does not take place, because the exudation is less, and the overlying periosteum is injured in such a way as to lose its osteo-genetic function, and when, after a time, it returns to its normal state, as shown in the examination of the various specimens referred to, either the exuded elements have disappeared, usually reabsorbed, or have become too old to feel the ossifying action of the periosteum. As stated, when discussing the development of bone, the normal function of the healthy periosteum is to supply the nutritive elements necessary to keep the bone in a sound condition, otherwise the bones could not preserve their symmetry, and their development would have no definite limits. In fractures with overlapping or marked displacement, we have seen that the extremities take no active part in the restorative process, but are united by an ossific mass deposited between the sides facing each other, a transverse section showing a direct continuity of substance. This osteoplastic development must be assigned to the periosteum, but in a manner quite different. from that formerly ascribed to it. We have noticed already in the ossifying callus, as early as the fifteenth day in the specimens from the rabbit, that the union between the old shaft and the new bone had become intimate, and that the new osseous substance was covered by new periosteum in direct continuity with that of the shaft at a distance from the fracture. When the exudation which is given out from the superficies of the two fragments meets, it blends, and, covered with the newly-developed periosteum, places the callus in a condition for ossification, and the union by new bone firmly joined is the result. The exudation of soft neoplasm, which is necessary for the formation of the callus, is of great importance here for deter mining more actively the irritation of the periosteum in the opposing sides of the fragments, otherwise there would be no reason why the external surface should preserve its normal condition, and the new osseous substance form only at the place where the fragments face each other, and between which is necessarily found the exudation in greater abundance. In compound fractures these factors which enter into the process of repair, vary with the condition of the injury and the disposition of the fragments. In spongy bones, where the displacement is generally inconsiderable, the most important share in the restorative process is due to the elements that compose the medullary or spongy substance, and more rarely do we find an imperfectly formed callus. A beautiful specimen illustrative of this is from the Warren Museum, and exhibits both modes of union. The patient sustained a fall three years before; death due indirectly to the injury. The anterior portion of the body of the twelfth vertebra is in large measure wanting, and separated from the eleventh by an inter-osseous space, but in the posterior part the osseous substance of the vertebra is not only in contact but very firmly united by a bridge of dense bone. There is a true ossific union externally between the portions of the fractured vertebra with a subperiosteal osteo-plastic layer of new bone, and upon the right side the folding together of the external plates is distinctly marked. The internal callus is owing entirely to a transformation of the elements composing the medulla. The study of an ununited fracture, the humerus for example, is instructive in this connection. Here, owing to motion, the medulla in the cancellated structure of the bone ossifies without union, and after a time, by the perverted action of a process intended to re-establish the continuity of a part, actually defeats it; for the bone-forming elements have gone on to a high development of ossific deposit, locking up their germinal material, and separating the cancellated extremities by a firm bony deposit. This must be surgi cally removed to bring the medullary elements in apposition before it can become an active factor of repair. Summing up the various factors which we find enter so widely into the modes of repair in fractures, we conclude that the germinal material which is effused in the vicinity of a fracture must be placed under certain defined conditions to secure therefrom au ossific development. From Ollier's many and varied experiments upon the periosteum, he found that to produce true ossification in transplanted periosteum, this must not only be revitalized by its connection of vascular character in its new relations, but must pour out or furnish an exudation of germinal matter sui generis. This exudation occurs only when the periosteum is irritated, not destroyed, and then there takes place a true ossific deposit, otherwise it does not produce bone. The process of consolidation in fractured bones is not uniform, but varies according to the quality and shape of the bones and the kind of fracture, as well as to the relations which are established between the fragments. These different elements, as we have shown, unite in many ways to produce the final result of consolidation. Although we have demonstrated that, strictly speaking, there is no primary union in bone as in other tissues, we may safely draw the conclusion from our studies which happily has been reached from the experimental standpoint of practice, that by careful and complete adaptation of the fractured parts, we place the various factors of repair in such a relation that they most readily combine to aid in the restoration of the part, and, by retaining them undisturbed for a certain period, we assist in producing a more certain and satisfactory result. HIP-JOINT DISEASE. (ILLUSTRATED.) DEATH FROM TUBERCULAR MENINGITIS, IN EARLY STAGE; BY DE FOREST WILLARD, M.D., PENNSYLVANIA. MICROSCOPICAL EXAMINATION. By E. O. SHAKESPEARE, M.D., PENNSYLVANIA. THE extreme rarity of opportunities for securing specimens of morbus coxarius in its early stage, and the absolute absence of such preparations from all our museums, render every carefully examined case of interest, and as I am unable, after diligent search, to find a single example in which the aid of the microscope has been brought to bear upon the subject at so early a date, I bring this now mutilated joint, together with these representations of the minute characteristics of the tissues, before you, that the attention of this vigorous Section may be so turned in this direction, that further examinations may in the future add to our present limited knowledge of the true early changes taking place in diseased joints. The case from which the specimen was obtained was a boy five years of age, who came to me at the Orthopedic Dispensary of the University of Pennsylvania, in 1877. His parents were poor, his hygienic surroundings bad, his condition feeble, his immediate parentage apparently healthy, but in the preceding generation phthisis had existed in two instances. There were three children, none having died. Although no known special injury had occurred, the mother had noticed lameness for a year, but at an institution for the treatment of deformities, was told that |