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XXXVI] absent in leprosy; generally, in the implicated spots it is complete, or nearly so. It should be particularly sought for towards the centre of maculæ, in the pale patches left after the fading of former maculæ, in the hands and feet, and in nodules of some standing. In no other skin disease is definite anæsthesia a symptom.

Vitiligo or leucodermia— sometimes called white leprosy, and by the vulgar very generally regarded as true leprosy— bears a certain resemblance to the pale post-macular patches referred to; not to mention other features, the absence of anæsthesia in leucodermia at once settles diagnosis. Further assistance may sometimes be got in doubtful cases from the fact that leprous spots rarely perspire. A hypodermic injection of pilocarpine is of use in bringing out this point.

The sensory and trophic lesions of syringomyelia might be mistaken for nerve leprosy, but the general history of the case, the history or presence in leprosy of macular eruption, of thickened nerve trunks, and of enlarged lymphatic glands, and their absence in syringomyelia, are mostly sufficient to establish a diagnosis. The occurrence of an acid-fast bacillus in the sputum of a patient coming from a country in which leprosy is common should be regarded with suspicion, and its true nature tested by injection of the sputum into the guineapig. " It is hardly necessary to point out the diagnostic marks of leprosy as against syphilis,* erythema multiforme, erythema nodosum, trypanosomiasis, lupus vulgaris, lupus erythematosus, psoriasis, eczema, lichen planus, cheloid, body-ringworm, erythrasma, pityriasis versicolor, pellagra, elephantiasis arabum, etc. Mistakes can scarcely be made unless from carelessness, or by someone completely ignorant of the nature, history, and symptoms of these diseases. In approaching the diagnosis of skin eruptions, localized pareses, muscular atrophies, and anæsthesia in patients living in or coming from a country in