It will now become necessary to inquire how certain exceptional cases are to be explained. Individual cases of the kind are represented in tubercle associated with cancer, or with venosity mechanically brought about.

(1.) The conditions mentioned as excluding tubercle, operate thus only in so far as the latter is based upon a hyperinotic crasis - an excess of fibrin. This does not, however, prevent the small fund of fibrin accompanying those conditions from being, under favorable circumstances, expended upon tubercle formation, which then becomes localized in a process of exudation.

(2.) The tubercle may be the product of a local inflammation, in which the fibrin becomes tuberculous.

(8.) The entire mass of fibrin may suffer a morbid change, effecting, as intercurrent disease, a consecutive tubercle crasis, which becoming exhausted by a corresponding exudation, again gives way to the original crasis.

It is thus that genuine tubercle, when concurrent with cancer, may be interpreted; and this the more readily, that true hyperinoses and fibrinous exudates not unfrequently do co-exist with cancer. The tubercle may be merely local, and the cancer no less so. It may, however, be local, and yet the cancer be a general disease. Or, again, it may be the product of an intercurrent primitive tubercle-crasis, or of a consecutive one derived from a local process, and co-ordinate with those hyperinoses and fibrin-exudations which not rarely supervene upon inflamed and ulcerated cancer, reflecting a secondary crasis.

(4.) As to the exemption afforded by venosity, there is no doubt that, to render it complete, a high degree of the latter is requisite. Since, however, we possess no scale whereby to ascertain directly the grade of a protective crasis, and to illustrate the exceptions, we must inquire whether it be not possible to arrive indirectly and approximatively at this recognition. In the absence of such a scale, certain anatomical changes must serve as the measure, so to speak, of the anomaly. They consist in the degree of heart affection (dilatation) present, this furnishing an available criterion for the amount of the impediment to the circulation, and therefore for the grade of the venosity. This approximative index with the aforesaid inferences, will be especially applicable where the precise extent of the impediment is not to be immediately summed up from anatomical data, as in lung affections, like catarrh and bronchial dilatation, emphysema, and preternatural density of the lungs.

We attach importance to this relation of tubercle to the venosity resulting from mechanical impediments in the heart and lungs, - as affording not alone proof of the fibrin-crasis being the foundation of tubercle, but also valuable indications for medical treatment.

We have now to consider the relative occurrence of tubercle in the different organs and textures, and its peculiar processes of repair.

It will be expedient, however, as a preliminary point, to determine what is signified by scrofula, - what is the distinction - if there be any - between scrofulous and tuberculous substance.

For our own part we hold tubercle and scrofula to be identical - tuberculosis and scrophulosis to be one and the same disease; and this upon the following grounds, namely:

(a.) One and the same elementary composition, both anatomical, and, so far as investigation has gone, chemical also. This applies with especial force to scrofulous substance, as compared with yellow tubercle.

(6.) Both are subject to the same metamorphoses, namely, softening and cretefaction.

(c.) The tuberculous and the scrofulous ulcer are identical both in the same, and in different organs; for example, the scrofulous skin- and the tuberculous intestine-ulcer. The same identity attaches to their cicatrix.

(d.) Both frequently coexist in the same organ, sometimes without, sometimes with, the appearances of inflammation.

The truth is, that the yellow tubercle is commonly called "scrofulous substance," more especially when it occurs in largish masses, and affects in the usual way the glands - the lymphatic glands - in children. Thus the same substance concurrently affecting the lungs and the bronchial glands is denominated, in the one instance tubercle, in the other scrofula.

A scale of the frequency of tubercle in the various textures and organs, offers but limited points of interest. According to our experience it would present in adults something like the following series, namely:

Lungs.

Intestinal canal.

Lymphatic glands, more particularly the abdominal and bronchial.

Larynx.

Serous membranes, especially the peritoneal and pleural.

Pia mater.

Brain.

Spleen.

Kidneys.

Liver.

Bones and periosteum.

Uterus and tubes.

Testicles, with prostate gland and seminal vesicles.

Spinal cord.

Striated muscles.

For children this scale does not answer completely. In them the lymphatic glands, together with the spleen, would take the lead, followed by the lungs with the bronchial mucous membrane, the brain, the serous membranes, etc.