The ensuing remarks appear to us well deserving of attention, as affording evidence of the imperfection of any summary scale of frequency.

(1.) At every point where capillaries occur, there may be tubercle. Epidermid formations and cartilage are therefore alone exempt from tuberculosis.

There are, however, vascularized organs in which tubercle very rarely, if ever, occurs; such are the salivary glands, the ovaries, the internal bloodvessel-membrane, the oesophagus, the vagina.

Even vascularized new growths may become the seat of tubercle.

(2.) If, which is most important, we consider tuberculosis individually, according to their primitive or to their secondary appearance, an entirely different scale is set up. The lungs and lymphatic glands, it is true, retain their uppermost rank, but are immediately followed by tuberculoses, which stand very low in the foregoing scale, namely, of the urinary system, of the female sexual mucous membrane, of the bones, of the testicles with the prostate gland and the seminal vesicles. Meanwhile tuberculoses of the intestine, of the larynx and trachea, of the serous membranes, of the spleen and liver, take a very subordinate position in the new scale, seeing that they seldom, if ever, become the primary seat of tubercle.

(3.) Accordingly, certain tuberculoses which in the first scale occupy a high place, possess but a very subordinate nosological import. They are seldom, if ever, primitive, but almost always secondary, dependent upon other tuberculoses often, indeed, only participant in general tuberculoses. The liver, spleen, kidneys, nay, in many cases the lymphatic glands, stand in this relation to tubercle.

(4.) Tuberculosis almost invariably attacks several determinate organs concurrently, at the outset or at a very early period. Of this communion we have examples, not only in the joint tuberculosis of lymphatic glands and of the implicated organs, but also in that of the brain and of the lymphatic glands; of the testis, prostate gland, seminal vesicles, and of the urinary organs; of the spleen and supra-renal gland, and of the lymphatic glands; of uterine and tubal, and of peritoneal; of pulmonary, and of intestinal, or of laryngeal tubercle.

(5.) Secondary tuberculoses have a sort of groundwork or starting-point in certain pre-existing tuberculoses. In other words, secondary tuberculoses accede to already existing ones according to a tolerably constant rule. Thus, tuberculosis of the lungs or lymphatic glands offers for all such secondary tuberculoses, a general point de depart, whilst, on the other hand, it commonly associates itself to most other tuberculoses. Tuberculosis of the serous membranes accompanies that of the implicated parenchymata; tuberculosis of the urinary system, that of the genital apparatus in the male. (See "Tuberculosis," vol. iv).

(6.) Again, the mode of production of tubercle varies in the different organs. Thus, upon serous membranes and in bone, tubercle is, for the most part, - upon mucous membranes, very frequently, - in lymphatic glands and in the brain, not unfrequently the product of inflammation.

(7.) In fine, it is worthy of note that in every organ tubercle, unless thrown out with much violence, has its almost invariable, and readily demonstrable point of incipiency. In the lungs it is at the apex, the upper third of the superior lobes; in the pia mater, at the part investing the base of the brain within the common groove, running from the chiasma to the pons Varolii and the medulla oblongata or about the fossae sylvii; in the brain itself, in and about the gray substance; in bones, in the spongy bones or parts of bones; in intestinal mucous membranes, in that of the inferior ileum; in the laryngeal mucous membrane, at the portion covering the transversus glottidis muscle; in the testicle, in the epididymis; in the female sexual apparatus, in the mucous membrane of the tubes and uterine fundus - that the deposition of tubercle first commences and concentrates itself.

(8.) Again, there are a few marked limitations set to the advance of spreading tubercle. For example, tubercle of the larynx never extends to the pharynx; uterine tubercle hardly ever passes beyond the internal orifice, so that the cervix uteri and the vagina remain exempt.

Tuberculosis very commonly proves fatal, if locally, by impeded function, by palsy of the affected organ, in consequence either of the extensive, acute deposition of tubercle into its texture, or else of the ulcerous destruction of the latter in the process of so-called tuberculous phthisis. Or the tuberculosis may, as a general disease, destroy life through impoverishment of the blood, through hydraemia or the serous crasis, an issue vastly favored where the tubercle is copiously and at the same time rapidly thrown out, and where local tuberculosis in important organs hinders the reproduction of blood.

The cure of tubercle may take place in various ways. Each of the metamorphoses of tubercle may become invested with the character of a healing process. Still, neither the decadence of tubercle, nor its ejection through the medium of ulceration, as local healing processes, are fraught with any value for the individual, unless accompanied by the extinction of the fundamental, tubercle-producing crasis.

The cure of tuberculosis as a general disease - as tubercle-dyscrasis - takes place now and then obviously through the intervention of some of the processes and conditions already adverted to as excluding tubercle; at other times, through influences entirely occult.

A question connected with the local healing process of tubercle here suggests itself, namely, as to the absorption of crude tubercle? The resorption of tubercle as formerly believed in, was probably first repudiated by Laennec, and after him by most pathologists; and although valid grounds can hardly be alleged for its impossibility, neither has it ever been proved by direct evidence, nor is it at all within the compass of likelihood.

The obsolescence, the cornification of gray tubercle, represents incon-testably its readiest process of involution. As a direct extinction of the tubercle, it would afford the completest cure, did it not concern a growth which would fail to become destructive if it abided in its primitive crude condition.

Of the two other metamorphoses affecting yellow tubercle, cretefac-tion of what has undergone softening unquestionably presents the most desirable process of repair, as will become evident from the following remarks concerning the other metamorphosis, considered as a healing process, or as the basis of one.

The softening of tubercle cannot of itself serve for a reparatory process. The elimination of softened tubercle through the instrumentality of ulceration in its vicinity, can alone pass current for such.

But, taking into account -

(a.) That it can only be brought about by ulcerous destruction of the textures.

(b.) That, although the aim of this ulcerous process be to heal, it may, when the tubercles are numerous, readily induce exhaustion.

(c.) That the attendant inflammation - the general disease being unextinguished - of itself determines tuberculous products, thus extending, without limit, the ulcerous consumption of the textures.

(d.) That even under favorable crasial conditions, an infection of the blood is possible in tuberculous ulcers (cavities).

Taking, we say, all these circumstances into account, this curative process must be regarded as widely subordinate to that of cretefaction, to which it stands in nearly the same relation as the removal from the body of a foreign substance by a debilitating ulceration, to the same substance being rendered innocuous by incapsulation.

The healing of a tuberculous ulcer or cavity, - of tuberculous ulceration, - can therefore only take place provided the accompanying inflammation, owing to extinction of the tuberculous crasis, ceases to deposit fresh tuberculous matter, and determines organizable products instead. The loss of substance is made up for by new-formed shrivelling scar-texture. Where the tubercle has not been completely eliminated in the phthisical process, the residue may become isolated by a pap-like inspis-sation and eventual cretefaction.