cess of the dentata, a deep hollow can be felt, caused, apparently, by the atlas and occipital bone having been moved forwards, (probably by the weight of the head,) beyond their proper relation to the dentata. The head also leans obliquely to the left side, as must have been the case with the man from whom the preparation was taken.

The patient first came under my observation in the end of March of this year, when the distortion of the neck was about the same as at present. She had suffered pain in the crown of the head, but not much in the neck, for about four months (the origin of the pain being attributed to influenza). At one time she was affected slightly with incontinence of urine, and had some pain in her legs; but she did not give up work as a domestic servant till three weeks before she applied at the hospital. Her chief complaint was then stiffness of the neck; she had also pains in both shoulders and arms; but there were no indications of paralysis in any part of the body. To give her the advantage of rest in the recumbent position, and counter-irritants to the neck, and to provide her with supports for the head, she was kept in the hospital till the middle of May. Early in June she was readmitted. She stated that soon after being discharged she had weakness in her legs, which prevented her from standing or walking; but as she lay on her back she had perfect power over her limbs; she had neither numbness nor spasms in the legs; occasionally she had incontinence of urine. Having been kept quiet for some weeks, without any symptoms of paralysis manifesting themselves, she was allowed to get out of bed and take moderate exercise. For some time back, wearing the supports to her head, she has sat up at her needle, and assisted the nurse in the light work of the ward; and arrangements are now being made to send her to the sea-side.

A cast showing the distortion is preserved in the Museum of the Middlesex Hospital School.

ON

THE MINUTE ANATOMY

OF

THE EMPHYSEMATOUS LUNG.

BY GEORGE RAINEY, M.R.C.S.,

DEMONSTRATOR OF ANATOMY AT ST. THOMAS'S HOSPITAL.

COMMUNICATED BY DR. TODD.

Received May 31st-Read June 27th, 1848.

THE form of emphysema which furnishes the subject of the following details is that which is called "Vesicular Emphysema," and the specimens of this disease, which have been selected for minute examination, are of the ordinary kind.

The subject from which the greater part of the preparations illustrating the facts described in this essay, and from which the drawings accompanying it were taken, was about forty years of age, and the general aspect of his lungs, especially in the vicinity of the emphysematous part, was healthy. There were, however, in some parts of the lung, a few small tubercular deposits.

Before the abnormal condition of the structures entering into the composition of the lungs, as they appear in emphysema, is described, a few observations on the normal state of these parts may advantageously be premised; and, the air-cells being the seat of this disease, these observations will be confined to them.

The only two structures entering into the composition of

the air-cells, distinguishable by the microscope, are capillary vessels, and the membrane by which they are invested and connected together. The capillaries are known by the minute oval spots on their coat, generally considered to be the nuclei of cells, as well as by the extremely faint outline of the coat itself. In the uninjected subject this coat can with great difficulty be distinguished, especially when the capillaries have no blood in them; but in the injected lung it is sufficiently evident in those vessels which contain only a small quantity of injection. Nerves are not recognizable in the air-cells, although it can scarcely be imagined that no nerves exist in these parts.

If a portion of injected lung, magnified twenty or thirty diameters, be viewed by reflected light, it is seen to be made up almost entirely of irregularly-shapen cavities—the aircells-differing very much both in size and form, but for the most part cuboidal. The dimensions of the air-cells differ greatly in different parts of the same lung, being the largest in those parts the most remote from its centre. They are frequently so large at the margins and extremities of the lobes, that these parts of a lung, retaining a good deal of air after death, are sometimes considered to be emphysematous when they are perfectly healthy. The walls of these cavities appear by reflected light to be formed entirely of a dense plexus of capillaries, consisting only of one layer of these vessels, which is so situated with respect to contiguous air-cells that the same layer forms a part of the two cells between which it is situated, one side of it bounding one of these air-cells, and the other side the adjacent one.* The air-cells communicate by large circular openings through which the air can pass freely from one into another. An indefinite number of these air-cells, surrounded by areolar tissue, and supplied by a branch of the pulmonary vessels, constitutes a lobule. The larger branches of the pulmonary artery and vein run in the intervals between the lobules, while the smaller ramifications run between the air-cells themselves, and send off

* See Plate IV. fig. 1.

branches in different directions to the nearest plexuses, in which they anastomose very freely with the radicals of the pulmonary veins, and also with the ultimate ramifications of the neighbouring pulmonary arteries.

The membrane connecting the capillary plexuses—“ pulmonary membrane "—is very thin, almost transparent, and made up chiefly of an irregular interlacement of extremely delicate fibres, which are most distinct around the openings of communication between the air-cells, where they appear to be somewhat circular. This membrane, whilst in a healthy state, is devoid of any regularly-formed corpuscles; the appearance of minute cellules may occasionally be observed in some parts of it, but these are so very rare, their form and size so irregular, and their situation so uncertain, that they cannot be regarded as an essential part of its structure, and may therefore be considered either as accidental or abnormal. pulmonary membrane lines the air-cells, and in passing from one cell into another encloses the plexuses of capillary vessels between the two cells: hence between each two contiguous air-cells there is one layer of vessels and two layers of membrane. This membrane has no regular covering of epithelium, the ciliated form of epithelium ceasing with the bronchial membrane, which extends no further than the termination of a bronchial tube in a bronchial inter-cellular passage.*

The

The office of the pulmonary membrane is to connect and support the capillary plexuses, and to form the immediate boundary of the air-cells. It appears to be the seat of disease in emphysema, as hereafter will be shown.

Having premised these observations on the minute structure of the air-cells, it will be more easy to render intelligible the changes which they undergo in the disease now under consideration.

If a very thin section, or even a mere fragment of emphysematous lung, especially if it had first been minutely injected, be examined by a lens of one-quarter inch focus, by transmitted light, the pulmonary membrane will be seen

* See Medico-Chirurgical Transactions, vol. xxviii. p. 581.