effusion which sometimes occurs very early, and which on that account has been called acute empyema.

When the effused albumen is susceptible of organization, blood-vessels sooner or later form in it, and it is gradually converted either into cellular tissue which binds the pleura together, or into an adventitious coating spread over one or both pleuræ, and which takes on all the ordinary functions of a serous membrane. As the organization of these new structures proceeds, they contract, and by their contraction induce various mechanical changes in the adjacent parts. When confined to the pulmonary pleura, they are found at an after period of various degrees of thickness, and rendering that membrane more or less opake, whilst the lung itself so situated is manifestly encroached upon, as shown by its rounded edges or actual diminution in size. The effects, however, of the contraction of these new tissues are most striking when the effusion has been very considerable, together with a copious deposit of plastic albumen upon the whole of the surrounding pleuræ. Under these circumstances, as the serum is absorbed and the albumen proceeds to organization, the contraction is often such as to draw the ribs into close approximation, to depress the shoulder, to diminish the size and alter the form of the affected side of the chest, and even to bend the spine, the lung probably being at the same time permanently bound down against the mediastinum and superior dorsal vertebræ. It is under these circumstances, also, that the diaphragm is occasionally drawn up considerably above its natural level in consequence of adhesions forming between the diaphragmatic pleura, and that covering the base of the lungs. Should a patient survive for some time who has had a pleurisy attended with copious effusion and a large proportion of plastic albumen,

we occasionally find on examining the body at an after period that the adventitious structure formed on each pleura is of considerable thickness, that it has acquired a remarkable degree of density, and that the two layers have either come in contact and united through the medium of a tissue differing somewhat in appearance from either of them; or we perhaps discover, although many months after the attack, a small circumscribed space where union has not taken place, and which is still occupied by a fluid.

Some of these permanent effects of pleurisy are distinctly discoverable years after the attack which produced them, even when the deformity is not such as to strike the eye of the observer. In such cases there remains permanently some degree of dullness on percussion, and the respiratory murmur presents various degrees of imperfection, being in some instances merely very feeble, in others tubular, and in others feeble and blended with a dry croaking sound.

As already observed, when the effusion is considerable, and when the albumen assumes a puriform character, as often happens in scrofulous habits, the changes described do not take place; instead of which, the effused matters are neither absorbed nor become organized; they remain more or less stationary, and thereby constitute

EMPYEMA.

This empyema is now and then attended with so little local disturbance as to escape detection altogether, and especially so when it occurs in infants and children. In such young subjects we have occasionally been led to suspect its existence by the remarkable paleness of the

face, and bloodless aspect of the eyes of the child, further inquiry eliciting from the attendants proofs of some previous indisposition, but probably several weeks before, and without its having been referred to the chest in particular. In the cases referred to, auscultation and percussion, and in two instances paracestecis thoracis, placed the matter beyond the possibility of a doubt. The same oversight has occurred and been detected in like manner in the adult, although with his perfect knowledge of having suffered pain in the side and shortness of breath weeks or months before. He probably complains only of general languor, some loss of flesh or strength, transitory flushes of heat, occasional sweats during the night, and slight hurry of respiration on making exertion. In most instances, however, the transition from pleurisy to empyema is sufficiently obvious, the disease quickly giving rise to well-marked symptoms of hectic fever, which, unless relieved by nature or art, gradually lead to emaciation, exhaustion, and death.

In some rare instances, the matter contained within the chest has caused ulceration of the pleura costalis, has pointed and burst externally, and the patient has ultimately recovered. More frequently, it excites ulceration in the pulmonary pleura, passes into the lungs, and is expectorated through the bronchial tubes; the communication thus formed between the bronchial and pleural eavity giving rise at the same time to pneumothorax. When this event takes place, the patient perhaps experiences a sudden pain or uneasiness within the chest, with oppression of the breath or sense of suffocation and cough, and presently afterwards expectorates pus, sometimes in small quantity at first, but often so exceedingly copious, that he seems to vomit rather than expectorate it. The

puriform fluid discharged in this way presents pretty uniformly the same appearances: it consists of irregular opake masses or lumps of a yellow or greenish yellow colour, floating in a thin and turbid serum. These discharges usually recur at uncertain periods, and vary in quantity from a table-spoonful to half a pint or more; the patient in the intervals either not expectorating at all, or merely rejecting some bronchial mucus, mixed perhaps with small portions of the pleural secretion.

The result of empyema communicating with the lungs is various; in some instances the distress of breathing and constitutional irritation are such as to prove speedily fatal; but in the majority of cases, the patient rallies from the first shock, and either gradually and slowly recovers, or continues to suffer from hectic fever, and ultimately dies, as if from phthisis pulmonalis, for which it has often been mistaken. A person, however, has continued for years to reject from the lungs, once or twice a day, a large quantity of extremely fœtid pus derived from empyema.

If we have an opportunity of examining the chest of a person who has recovered from an empyema which has been evacuated through the lung, we commonly find the organ reduced to an extremely small size, firmly bound down by false membranes, and its internal structure converted inte a dense and almost cartilaginous cellular tissue, including within it the remains of the larger bronchi; whilst at the same time, we either have the two pleuræ closely and inseparably adherent everywhere; or discover at some part, a small space remaining ununited, and communicating by smooth and polished orifices with the bronchi, through which the matter of the empyema had passed.

Diagnosis of Pleurisy.-When investigating the physical signs in a case of real or suspected pleurisy, it must

be carefully borne in mind, that dullness of sound on percussion, and feebleness or entire obliteration of respiratory murmur, may exist independently of any recent disease whatever; these morbid indications being the result of a previous attack of the complaint. Pleurisy is to be distinguished from pneumonia by the acute pungent pain, and by the absence of the pungent heat, the cough and peculiar expectoration, and the crepitating rattle so characteristic of the latter. When pleurisy has advanced to its second stage, it is sometimes more difficult to determine whether the dullness of sound, the bronchophony, and bronchial respiration, often present, arise from pleuritic effusion or from pneumonia advanced to hepatization. In pleurisy, these signs are usually preceded by acute pain, which is not the case in simple pneumonia; in pleurisy the dullness of sound takes place more suddenly and over a much larger extent of surface than in pneumonia; in pleurisy the bronchophony is generally mixed with one of the modifications of gophony; in pleurisy there is very seldom any cough or expectoration unless complicated with bronchitis, and never the peculiar sputa observed in pneumonia. It would appear, that when a thin layer of solid albumen, with little or no fluid, overspreads the pleura, the bronchophony is so clear and unmixed with ægophony that it may lead to a belief in the existence of pneumonia advanced to hepatization; but the previous pain, the suddenness and great extent of the dullness on percussion, and the absence of cough and peculiar expectoration, will seldom fail sufficiently to declare the nature of the case. It is right to observe, however, that the two diseases are frequently combined, and then we have the signs of both more or less strongly marked.

From bronchitis, pleurisy is to be distinguished by the