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XXXVI] finger having been entirely absorbed, the nail springs, as it were, directly from the knuckle. Perforating ulcer of the sole of the foot, usually under the ball of the great toe or the heel, is a very common lesion in nerve leprosy.

On the whole, the advance of this form of leprosy is much slower than that of the nodular variety. The average duration of the latter is from eight to nine years, of nerve leprosy about eighteen years. Often such lepers live much longer— twenty, thirty, or even forty years. The end of these cases is quite as sad and repulsive as that of nodular leprosy. Death seldom results directly from the disease itself, but usually from diarrhœa, chronic nephritis, phthisis, pneumonia, or bronchitis.

As already explained, in most cases of nodular leprosy trophic changes from implication of nerve trunks ultimately supervene. Similarly, though not so frequently, nodular infiltration of the skin may appear in the course of what originally seemed to be a case of pure nerve leprosy. In yet other cases nodular and nerve lesions concur from the outset. In one or other of these ways what is known as mixed leprosy is produced. The lesions are in no way different from those already mentioned, and therefore this form of the disease does not call for more detailed description. Pathological anatomy. Bacillus leprœ.— The lesions of leprosy are the result, direct or indirect, of the proliferation of the Bacillus leprœ in the tissues. This parasite (Fig. 88) in size, shape, and staining reactions closely resembles the bacillus of tubercle. In length it is from half to two-thirds, and in breadth about one-sixteenth the diameter, of a blood corpuscle. The ends of the rod— which is always straight— are in many specimens somewhat attenuated; and in many instances— presumably in old bacilli— a moniliform arrangement of the protoplasm, as if from spore formation or, according to