The affections of the skin produced by tuberculosis have shown such a variety of form that they offer nearly the same interest as those arising from syphilis. On account of the complex construction of the skin the tubercular lesions must present a different appearance according to the organs and tissues of the skin involved. When the glands of the skin are affected we see lichen scrofulosorum or folliculitis; when the lymphatics are affected, the disease manifests itself in the form of tubercular gumma, and as verrucous cutaneous tuberculosis, or lupus, when the papillary layer or the derma is invaded.
The cause of these eruptions is the tubercle bacillus, which is found in the structure of the skin. We have, however, other cutaneous eruptions where no tubercle bacilli are present, and they are the result of its toxic products. The toxic power of the tox-albumins has been already demonstrated, and it