Note 29 — DISSERTATION II. CONTINUED.

Although, in general, an abscess has little tendency to extend itself deep down, but rather moves toward the surface, although so far from it originally, that, had the action extended equally in all other directions, the size of the abscess must have been immense; yet, when it is situated over a cavity, it may proceed toward that as if to an external surface. Even, however, in this case, the general law, of all actions tending to the skin, obtains; for the progress outward is much quicker than that inward; but, if the action commenced near the surface of the cavity, as is commonly the case, the difference of the distance will compensate for the superior tendency to extend outward; and, therefore, the abscess may burst at the internal surface into the cavity.