character, and must ever be open to numerous exceptions. But I doubt not that those whose opportunities of observation upon the various causes of this disease have been extensive, will readily admit the influence, although in different degrees, of the several conditions which I have thus attempted to describe.

ANY severe or long-continued consumptive predisposition may develope the disease without the supervention of an exciting cause; this we see exhibited in certain cases where either the hereditary taint, or the acquired morbid state of nutrition, is sufficient, of itself, to produce the tubercular substance. One predisposing cause, also, supervening upon another, may act the part of an excitant; thus, an hereditary tendency may be brought to light in consequence of unhealthy occupation, or mental distress, or by something which has reduced the general vigour of the system; and to this mode of origin a vast number of phthisical cases are manifestly due. But it often happens that something of a more active kind, but which, in the absence of pre-existing liability to the disease, would have had no such effect, has led to its developement; and it is this which constitutes what is usually understood as the exciting cause. Certain inflammatory conditions of the chest, catarrh, influenza, fever, pregnancy, lactation, etc., have more or less influence in this way, and therefore require to be noticed separately.

Bronchitis. Some persons, although strongly predisposed, will exhibit nothing to justify the least apprehension, until an apparently accidental attack of bronchitis proves the starting point of ordinary phthisis. Cases of this kind, however, are not so frequent as they might appear to be, since many, which seem to have such an origin, are merely instances of severe bronchial inflammation immediately following the tubercular formation. The bronchitis to which persons of consumptive predisposition are most subject, is not generally of an acute form, but of that sub-acute and less active kind which is not immediately dangerous, but which leads to an irritable condition of the bronchial mucous membrane, rendering it peculiarly liable, upon the slightest occasion, to become the seat of renewed inflammation; and it is to repeated attacks of this description that the commencement of phthisis is frequently traceable.

But bronchitis, essentially chronic, may pass into confirmed phthisis, should it either be conjoined to other causes having a tendency to reduce the health, or be superadded to the slightest hereditary tendency. Cases illustrative of this are chiefly to be found amongst persons of advanced age; and it is, perhaps, the most common way in which consumption is developed after the middle period of life. It is seen also when what is termed "winter cough" increases, year by year, in severity, and finally terminates in ordinary phthisis.

It occasionally happens that persons having a tendency to scrofulous disease, are attacked with bronchitis of a low and peculiar character, producing extreme prostration, and leading to the formation of a tubercular secretion, much of which seems to be deposited in the smaller ramifications of the bronchi, as well as in the pulmonary structure. This variety of the disease might be termed scrofulous bronchitis, and is, perhaps, the most unpromising under which consumption can be produced; running, almost invariably, a rapidly fatal course, and constituting many of the cases commonly described as" acute phthisis".

Pneumonia. Those who possess a strong consumptive tendency are, as a general rule, infinitely less liable than others to acute pneumonia; and it is owing to this circumstance, as well as to the greater readiness with which such persons are affected with bronchitis, that we so seldom find pneumonia of an acute kind developing phthisis. That it might, at any time, do so, there cannot be a doubt; but, practically, such cases are rare.

In persons of highly scrofulous diathesis, a low form of pneumonia occasionally acts as an excitant of phthisis. In such cases, the inflammatory process appears to assume, either at first, or after a short period, a strumous character, and to be attended by a morbid tuberculous secretion, instead of the fibrinous one of healthy inflammation. This form of disease might be termed scrofulous pneumonia;

and although not very common, yet, like the strumous variety of bronchitis, it usually terminates in a variety of consumption both severe and intractable, and is closely allied to what is often called "acute phthisis".

There is, however, another, and perhaps more common way, in which pulmonary inflammation may be productive of consumption. When pneumonia has been neglected, or, having been but imperfectly recovered from, has passed into a chronic form, and some depressing cause has supervened, it would appear as if, in some cases, its inflammatory products, instead of being absorbed, degenerated into something allied to, or identical with, tubercular matter softening is then a very rapid process, and the patient is unexpectedly found to be in an advanced stage of phthisis. What is termed “tubercular infiltration”-in which a large proportion, or perhaps the whole, of the lung is of a grey and glistening aspect, here and there broken down into soft patches of a yellow tuberculous-looking substance-has, in all probability, this mode of origin. In such cases the apices of the lungs are, at first, less affected than the bases, but they become more implicated as the morbid process advances, until at length, they are sometimes more filled with tubercle than any other part. I have seen the most robust individuals thus fall the prey of rapid consumption; and it is, perhaps, in such persons that this variety of phthisis is the most