employed by nature for the removal of dead bone; and Mr. Syme mentions similar instances.

We would remark that a number of negative instances do not disprove the occasional occurrence of a fact. No one contends that a sequestrum is always absorbed. Mr. Gulliver goes on to remark :—

"But if the sequestrum is not absorbed, what becomes of it? It may be remarked, in the first place, that they are not all cases of necrosis that have been so denominated. Under this head, in the museums of anatomy, a class of specimens is sometimes presented to our notice which seem to me to admit of an explanation differing from that commonly assigned to them. These are generally the shafts of the long bones, prodigiously thickened and irregularly perforated with holes for the transmission of blood vessels, or by cloaca leading to the cavities of abscesses, and sometimes singularly crooked and mis-shapen, as if at one period of the disease they had been softened, and influenced by mechanical force. In the centre of such bones a very small portion is sometimes found dead and detached, but more frequently the shaft is simply very thick and dense throughout. The former have frequently been regarded as examples in which the absorption is nearly effected; the latter as the completion of this process. It is probable that both are instances of long continued inflammation of bone, the first attended with death and separation of a small central fragment, which had afterwards undergone no alteration of form, and that the second was never at any period a case of necrosis.

The deposition of a cylinder of new bone around the old one, is not an absolute proof of the death of the latter, as I have had frequent opportunities of ascertaining in the course of my experiments. Nature often exhibits a prospective contrivance in the formation of a new osseous shell, or in the enlargement of a part of the old shaft, before actual necrosis has taken place; a fact which has not escaped the observation of Mr. Russell and Dr. Macartney. In the museum of St. Bartholomew's hospital, there is the tibia of a dog incased in a shell of new bone, and partly detached, but the injection has run pretty freely into the old bone. In such instances, the part which has suffered the most intense inflammation may become partially eroded, and gradually removed by absorption, if it retain its vitality long enough, while a deposition of new osseous matter gradually supplies the loss, death of the old bone having formed no part of the phenomena. This is probably the explanation of many cases of alleged absorption of dead bone. But if a piece of bone truly dead be inclosed within a new osseous cylinder, then it is indeed a bad case of necrosis, which the patient will carry to the grave with him, unless relieved of the sequestrum otherwise than by absorption.

The worm-eaten appearance on the surface of many sequestra may be explicable in two ways. The most numerous examples of this kind are those of necrosis of the inner layer of the shaft of the long bones, with thickening of the outer portions,-a form of disease known to Bordenave, Haller, Collison, and Tenon, and since more fully explained by Brun, Brugnoni, Penchianati, Dr. Knox, Mr. Syme, and others. In such cases, irregular death, and separation of a portion of a bone, may be expected to produce an equally irregular surface: the part would not necessarily die in a determinate form, any more than in cases of sloughing of soft textures; and when the outer layer of an entire cylinder of necrosed bone presents erosions on its surface, it seems more reasonable to refer these to the effect of the ulcerative process, while the part retained its vitality, than to the action of the absorbents after its death.

* It is proper to notice that Mr. Stanley considers this to be doubtful. The preparation will be found under the head of "Bone," No. 10.

The aspect and situation of the granulations is equally inconclusive. They are seen to be extremely vascular, and accurately corresponding to the indentations on the under surface of a superficial layer of dead bone in progress of exfoliation, a case in which it has not often been supposed that the dead portion suffers diminution from the absorbents, the action of which is confined to the surface of the living bone in immediate contact with that about to be separated. The vascular structure adjusted to the superficial excavations on the surface of the sequestrum, is what might be expected from the work of exfoliation in some instances, or from the extension of the ossific process into the vacant spaces in others." 7.

3. Mr. Gulliver is not aware that the absorption of the fang of a transplanted tooth is a well-authenticated fact; but, if so, it would seem to indicate that the tooth, having preserved its vitality, had become a part of the living body to which it was attached, and accordingly subject to its laws.

Such are the reasonings of Mr. Gulliver. It will at once be admitted that they are fair and forcible, that they explain many supposed instances of absorption of dead bone, and that they tend to throw doubt upon the doctrine which unreservedly avails itself of such a process. But they are certainly not so staggering nor so conclusive as to make us deny its existence.

We turn to Mr. Gulliver's experiments, nineteen in number. We shall select such as are calculated to establish leading points.

Experiment 1.-A thin portion of the surface of the shaft of a human tibia was kept in contact for seventeen days with a large ulcer, studded with granulations, in a man's leg. The bone having been removed, dried, and weighed, was found to have undergone no alteration either in weight or appearance.

In the next three experiments a portion of human bone was introduced into a seton in the back of the neck. The following may be considered a representative of all.

Experiment 4.-A section of the shaft of the human humerus, weighing 10.7 grains, and comprehending the entire thickness of the bone, was intro duced into a seton at the back of a man's neck, and retained there sixty-five days. The suppuration was at first scanty, but became copious during the latter five weeks. The bone was removed, and found to have undergone no alteration in appearance, but it had increased exactly one-tenth of a grain in weight, probably from some albuminous matter which was not entirely dissipated by drying.

In the next four experiments, a portion of bone, in three instances human, was introduced into the soft parts of a dog's leg. Two of the experiments will exhibit the results of the four.

Experiment 6.-A portion of the shaft of a dog's thigh-bone, weighing 7.8 grains, was introduced deeply between the muscles and periosteum of another dog's leg, and kept there two months. Suppuration was soon established, and continued till the animal was killed. The bone had suffered no alteration whatever. The cavity in which it had lain was very vascular, being made deeply red by injection with size and vermillion.

Experiment 8.-A thin portion of the shaft of the human humerus was

placed in the subcutaneous cellular tissue of a dog's leg, and allowed to remain there four months. The wound soon healed, and continued sound till the animal was killed. The bone had suffered no change whatever it adhered slightly to the cellular substance, so as to stretch out the filaments of the latter as the bone was pulled away.

In the remaining eleven experiments, portions of bone, either human or otherwise, were introduced into the medullary canal of the tibia of rabbits, and retained there for a longer or a shorter time. The main experiments

are:

Experiment 11.-A portion of the shaft of a rabbit's tibia, weighing 2.1 grains, was put into the medullary canal of the tibia of another rabbit, and retained there thirty-four days.

The foreign bone was found to have undergone no change; it was surrounded by highly vascular lymph, and there was a large cyst, which had not yet burst, containing a white, concrete, purulent matter, and communicating with the cavity of the tibia. (E. P. B. 35 and 36, in the museum of the Army Medical Department.)

Experiment 12.-A piece of the shaft of a rabbit's tibia, weighing 1.5 grain, and a bit of the spongy extremity of the same bone, weighing one grain, were kept in the medullary cavity of another rabbit's tibia for twentyfive days. The weights were marked on these portions of bone with a blacklead pencil.

On being removed and dried, the first portion was found unchanged, and the second had increased one-tenth of a grain in weight, probably from matter which had not been dissipated in drying. The pencil marks were not obliterated.

There was much inflammation of the limb, and pus with vascular lymph surrounded the adventitious portions of bone. (E. P. B, 48 and 49, in the museum of the Army Medical Department.)

Experiment 15.-A bit of the shaft of a rabbit's tibia, weighing 2.2 grains, was introduced into the tube of another rabbit's tibia, and kept there seven weeks. The wound healed in the course of a few days.

The adventitious bone weighed 2.37 grains, and it was firmly imbedded in the medullary canal. The increase of weight was accounted for by two well-defined specks of new osseous matter deposited on its surface; and these deposits were removed and analysed by Dr. Davy, who found their composition to be that of true bone. (E. P. B. 57 and 58, in the museum of the Army Medical Department.)

Experiment 19.-A splint of a man's bone was introduced into the medullary canal of a rabbit's tibia. The animal became healthy and playful after the operation, and was kept as a pet in the house, for upwards of fifteen months, until it died. The inclosed bone was found to have suffered no change; it was separated from the tibia, which was somewhat thickened, by boiling. (C. 58, in Mr. Liston's collection.)

The foregoing experiments are certainly interesting, and must tend to

breed extreme scepticism with regard to the absorption of dead bone. Mr. Gulliver remarks, and fairly enough, that:

"These experiments are selected from a great number which I have made, all tending to the same conclusion. They have not been sufficiently varied and extensive to admit of being adduced as peremptory proof of the impossibility of the absorption of dead bone, in opposition to the incontestable power of the absorbents in the removal of inorganic particles from the living body, but I conceive that it is now fully established, with how much difficulty dead bone is subject to absorption, and that whatever may be the agency of this process in the removal of living parts, it can no longer be regarded as the means by which the sequestrum disappears in cases of necrosis" 18.

There is a point to which Mr. Gulliver directs attention, and which, undoubtedly deserves it-the deposition of new bone upon the old, and their adhesion or consolidation.

"It appears to me to be a very interesting fact, that a tissue which has been long dead should possess the power of attracting, as it were, particles similar to itself from the blood. To complete the resemblance to assimilation, we have only to suppose the dead matter to be porous, and the new particles attracted to its interstices." 19.

Unless our ideas on the subject of the connexion of living and dead parts are erroneous, we must suppose that some vitalization of the included bone took place, in order to enable the new bone to adhere to it. If such adhesion could occur, why should not absorption? The latter appears to imply less vital force and exertion, because the absorbed part may be passive, as the aliment received into the system is. But leaving this question, we beg to call our readers' attention to the entire memoir, and the actual experiments.

VII. ON THE PROPORTIONS OF ANIMAL AND EARTHY MATTER IN THE DIFFERENT BONES OF THE HUMAN BODY, By G. O. REES, M.D. F.G.S.

The object of Dr. Rees has been to determine the cause of the great discordance in the results of chemists who have occupied themselves in determining the proportions of the earthy and animal matter contained in human bone. He thought that different bones might possibly possess different quantities of each. The result of analysis has proved this supposition corIt seems tolerably certain that the differences in the results of chemists may be assigned to three different causes, viz.

rect.

"1st. The employment of different bones for analysis; nearly every bone having a proportion of earthy and animal matter peculiar to itself.

2nd. The bones used for examination being differently prepared, and containing more or less of fat, which will be estimated in the analysis as animal matter of bone, whereas it is merely an infiltration into its structure,

3d. The loss of different quantities of carbonic acid during decarbonization, owing to its conversion into carbonic oxide gas, which escapes at a low heat from carbonate of lime when carbonaceous matter is present. A portion of carbonic acid must almost necessarily be lost by bone-ash during incineration."

408.

The experiments of Dr. Rees were made on bones from the same adult.

They were similarly prepared, quite dry, and free from fat, periosteum, and cartilage. After the decarbonization of each specimen, he took the precaution of supplying the loss of carbonic acid which it had experienced, by moistening the result with a solution of sesqui-carbonate of ammonia, and then carefully applying heat to low redness.

The following were the results of analysis :

..44.00

43.47

Metatarsal bone of great toe 56.53....

The following conclusions seem to flow naturally from the foregoing analyses :

1st. The long bones of the extremities contain more earthy matter than those of the trunk.

2d. The bones of the upper extremity contain somewhat more earthy matter than the corresponding bones of the lower extremity; thus the humerus has more than the femur, and the radius and ulna more than the tibia and fibula: this difference is, however, small, being about one-half per cent. 3d. The humerus contains more earthy matter than the radius and ulna; and the femur more than the tibia and fibula.

4th. The tibia and fibula contain, as nearly as possible, the same proportions of animal and earthy matter, and the radius and ulna may also be considered alike in constitution.

5th. The vertebra, rib, and clavicle are nearly identical as regards the proportion of earthy matter; the ilium containing somewhat more of earths, the scapula and sternum somewhat less; the sternum containing more earthy matter than the scapula.

6th. The bones of the head contain considerably more earthy matter than the bones of the trunk, as observed by Dr. J. Davy; but the humerus and other long bones are very nearly as rich in earths.

7th. The metatarsal bones may probably be ranked with those of the trunk in proportional constitution.

* Solid parts of the shafts were used for experiment.

+ Hard squamous portion.

§ Solid external crust.

Coracoid process.

Arch of dorsal.

Near the crest.