ances may be very different, according as a small or a great number of tubercles are evolved. In the former case they generally attain a larger size than in the latter and then they may either produce a vomica, or a tumour, or both. In the latter case, (where a great number are evolved,) if they advance simultaneously, no one can much outstrip the other in growth, in which case we usually see a great number either approximating or in actual contact, and with qualities vary. ing according to the nature and period of their progressand it is this progress in the common tubercular phthisis, that we are now to attempt to trace.

In the earliest stage of pulmonary tubercles they are incog nizable by the touch, on account of their delicacy and elasticity; but they are visible as small vesicular transparent bodies shining amid the unchanged surrounding texture.

"Should any of them happen to have been generated on the surface of the membranes, they there may be seen clustering together, and resemble both in size and general character the beautiful globu lar incrustations, which beset the stalks and leaves of the ice plant." P. 10.

In the human subject it is rare that tubercles can be seen in this their primitive state; but only at a somewhat later period of their progress. At this period the softness and delicacy of the vesicle is lost, its transparency diminished, and its size increased. On examining the lung where they exist, a distinct granular sensation is communicated to the fingers.

"The progress from this period is evinced by an augmented size, a firmer texture, and a complete loss of transparency, a yellow opake body being perceptible. In this state they sometimes fall into ulceration and prove fatal. But before such an event takes place, it occasionally happens that many of them advance further and exhibit other appearances. Except where they are in contact with each other, they go on increasing in bulk. The coats of some become thick and hard, and almost cartilaginous; while their contents may vary both in colour and consistence. Others proceed in a different way, and are condensed into solid bodies of an uniform texture, the cysts and the containing parts being scarcely discernible from each other." 11.

The appearances in those who die in this state, are as follow-some tubercles will be found firm and solid-others with thick dense coats, containing curdy, cheesy, or purulent-looking substances: others, again, will appear partly des troyed by the progress of the ulceration, exhibiting only a firm, almost cartilaginous remnant of emptied cyst, conspicuous among the surrounding disease. "Should a great

Vol. III. No. 12.

5 I

number of contiguous tubercles have fallen into this state, deep and extensive and irregular shaped fissures and excavations are thereby formed"

"In the progress of the tuberculous disease, there are corresponding changes in the surrounding lung, which it is necessary now to note. At the first development of tubercles, whether in the lungs or elsewhere, the surrounding texture seems to undergo little or no alteration. The lung retains its fresh pink colour, and its light elastic feel, and there appears to have been no interruption either to the circulation of the blood or air.

"As the tubercles increase in size and in density, and approximate each other, they cause greater disturbance in the system. The blood is impeded in its circulation, and respiration is of course rendered quick and laborious on slight exertions. The consequences are obvious, the lung becomes firmer and of a darker colour, and ultimately exhibits that appearance, which has been supposed to be indicative of a particular species of disease.*" 13.

This dark and indurated state of lung is occasionally obliterated by the increase and coalescence of tubercles into a dense and solid structure, with here and there a trace of the original tuberculous character, to the total exclusion of every thing like the pulmonic texture.

"The changes of structure above described, are indicated by corresponding symptoms. Tubercles, in their incipient state, may exist without producing much disturbance in the system, and they may pass onwards towards consolidation, if they be not very numerous, without affording almost any signs of their existence; and in this consolidated state they may continue, and not in any material degree tend to abridge life. The unexpected occurrence of solid tubercles or tumours in the lungs of those, who had not previously manifested any symptoms of such disease, bears me out in this assertion. When tubercles are fully consolidated, there is the strongest reason to believe that they do not subsequently fall into a state of suppuration. This occurs chiefly in those that were not destined to arrive at this point.

"The consolidation therefore just referred to, may in some measure be considered as a favorable termination to tubercles, as life has been found to be compatible with their existence, except in cases where they occupied a large proportion of the lung, or produced accretion of the membranes. It is in that period of their progress, which is intermediate between the state last mentioned, and their first developement, that all the symptoms, characteristic of tuberculous phthisis occur. This will be apparent by attending briefly to the ordinary progress of the disease.'

15.

It is well known that, in a person who has tubercles, we

• Hepatization.

find cough at intervals, without expectoration, but with occasional oppression about the chest, and hurried breathing on slight exertions.

This state may exist, at intervals, for many months, or even years, without any other sign of disease. A catarrh may encrease these symptoms, or render them more permanent, and then some yellowish or whitish expectoration may appear, mixed with blood-or a gush of blood may precede the occurrence of expectoration. Our author has known this hæmorrhage repeatedly happen and ultimately prove fatal, where there was great consolidation of the pulmonary tissue by tu bercles, and yet, where there was never any expectoration of the tubercular matter itself. It is from this, and other kindred cases, that he infers, that tubercles, once consolidated, do not subsequently suppurate or ulcerate.

Such expectoration as above described is, he thinks, a sure token of a tuberculous disease. One of them has given forth. its contents, and more may do the same thing, though at intervals more or less extended, with proportionate recoveries for the time being. There may even be ultimate recovery after successive events of this kind, shewing, Dr. B. thinks, that there either were not a great number of tubercles in a state to undergo the ulcerative process, or that the tubercles were brought by accident or treatment into a quiescent state, and subsequently consolidated. It is comparatively seldom, however, that this termination is obtained either by nature or art.

Our author observes, that the matter expectorated is of different kinds-that from excited mucous surfaces being different from the contents of a tubercle-and this last differing materially from the purulent secretion that issues from the ulcerated internal surface of a tubercle after it has discharged its contents. The appearance of pus, therefore, by no means necessarily indicates the presence of tubercles, "as is gene-. rally supposed."*

The dark-coloured induration of the lung before alluded to, does not attend tubercles in their early state, though it more or less accompanies them as they advance. It readily falls into decay when the enveloped tubercles are undergoing a process of dissolution. When this induration occurs to any extent, it occasions or increases the difficulty of breathing,

• We are not aware that medical men generally suppose that where pus is, there a tubercle must be. Nothing can be more common than the knowledge that pus may come even from an unbroken surface, when it is strongly excited.

and there is generally a livid appearance about the lips and

countenance.

Great variety occurs in respect to pain. Sometimes there is little or none throughout the disease-" at other times the disruption of every successive tubercle seems to be accompanied by deep-seated and acute darting pains."

"Tubercles in the pleura cause sometimes effusion into the cavity, more frequently accretion. When the latter event takes place, there is cough and dyspnea and a rapid pulse, but no expectoration. But when tubercles in the lungs, in a state of ulceration are added to it, we have in conjunction with the symptoms already enumerated, the expectoration of tuberculous matter, hectic fever, &c. The mode of breathing in cases, where accretion of the pleura has taken place, is different from what it is when the lungs are free within the cavity. In the first mentioned instance, the shoulders are drawn forwards, the ribs do not move as in the natural state, the whole chest heaves at once; and most of the muscles on the trunk of the body seem to be called into action.'* On striking the chest of a person in this state, the sound emitted is like that produced by the percussion of a solid body, very different from that which a healthy chest affords, or when disease exists in the lungs without accretion of the membranes." P. 21.

When a patient happens to be cut off by another disease, before the tuberculous affection has run its usual course, the same lung will sometimes present examples of all the progressive changes which our author has described in this, and his preceding Inquiry. An interesting case, in illustration, is given, and a plate from the same subject.

It is impossible to describe all the varieties of appearances which may arise from the peculiarities in the structure and arrangement of the tubercular masses; but, there is one which is so very common, that it requires to be noticed. It occurs when tubercles, originally soft and circular, grow in size and mutually press upon each others' boundaries. The globular character is thereby destroyed, and the divisions between each, so far as they can be traced, are angular, so that instead of circles, we have squares or figures of different kinds.

The extent to which tuberculous diseases may proceed without producing symptoms of pulmonary consumption, is much greater than could, a priori, be expected. Our author relates the case of a lady, who never exhibited any signs of pulmonary disease, the symptoms being rather those of an affection of the stomach and stricture of the oesophagus. Some weeks before she died, she was seized with symptoms of pneumonia.

Enquiry, p. 170.”

Very frequent and large bleedings produced little effect. She expectorated pretty freely, but the dyspnoea became distressing, and she died. On examining the lungs, he found strong, but unlooked-for proofs of long existing disease. Almost the whole posterior portion of each lung was transmuted into a dense and nearly cartilaginous substance. Where the density was greatest, there the character of tubercles was obliterated; but it gradually re-appeared as they receded from this point, till, at last, their figure and boundary became perfectly distinct. All these appearances are accurately pourtrayed in the fifth plate. Two dissections are here given, shewing the progress of tubercles, from the smallest forms to the largest, in the pleura, liver, mesentery, and peritoneum.

CHAP. II. This is on Tuberculous Diseases in the Inferior Animals.

Hitherto, in the present work, our author has kept out of sight his opinion respecting the hydatidical origin of tubercles, because, he was desirous that any degree of doubt which might still be attached to it, should not be permitted to obscure what may be demonstrated to occur in the progress of tubercles. This opinion, however, he has occasion incidentally to allude to, in tracing tuberculous diseases in inferior animals. Our author has selected the principal part of his descriptions from the work of M. Dupuy, an eminent French veterinary surgeon; his testimony being the more valuable, he observes, because it is, in a manner, extorted from him by irresistible evidence, in direct opposition to the main tenor of his work.

The glanders, as it is vulgarly called, is strictly a tuberculous disease attacking the lungs of the horse, and bearing the closest analogy to pulmonary consumption in the human subject.-Farcy, Dr. B. observes, is likewise a disease of the same genus, affecting another part of the animal. In glanders, the morbid appearances are not confined to the lungs. The nasal cavities, and the lymphatic glands, in many parts of the body, are also generally diseased.

We shall extract the following case from Dupuy, as our author thinks it bears strongly on his doctrine of the hydatid origin of tubercles.

"A cow, six years of age, was killed on the 2d of February, 1819. The body was examined immediately, and the following appearances were found. The pulmonary tissue was very much altered. It contained many cysts, enclosing hydatids of different magnitudes, from the size of a pea up to that of a goose's egg. Other cysts, of which the coats were of the consistence of cartilage, and even osseous, were filled with a substance analogous to that of bone;