In the nerves the bacilli are found partly in round cells, which lie around the vessels and between the nerve fibres, and partly in the cells of Schwann’s sheath; here also they break down into granules, and in time completely disappear. The finer details of the affection of the nerves are best studied on the ciliary nerves when the eye is affected, because there one can examine the finest nerves without cutting sections or putting them through any manipulation which might injure them. One often sees the myelin sheath pressed in by bacilli or cells filled with granules (_Plate XII, Fig. 2_), and one finds nerve fibres without a myelin sheath and with a more or less atrophic axial cylinder (_Plate XII, Fig. 1_). These drawings clearly explain how the pressure on the axial cylinder at first causes pain, and later, when atrophy has set in, anæsthesia. And one can also understand that when the leprous affection passes off without complications, the axial cylinders are again restored and become functionally active. But on those places above referred to, where the nerves run superficially over bones or joints, and are exposed to pressure and stretching, secondary inflammation is added to the process. While the primary leprous affection hardly appreciably thickens the nerves, the secondary inflammation causes a very marked thickening. The ulnar nerve at the elbow may attain a diameter of 7 to 8 mm. or more, and when the secondary inflammation disappears the connective tissue contracts, and the previously thickened nerve becomes thinner than normal. This whole process usually advances very deliberately, and years are required before anæsthesia is developed to its full extent. While the section of the thickened nerve is quite smooth and of a pale brown colour from the numerous globi present, the section of the atrophic nerve, though also smooth, is as pale as the section of a tendon. It consists almost exclusively of connective tissue; every trace of bacilli has disappeared, and one sees hardly a suggestion of nerve fibres. The leprous affection is healed, but only a completely functionless rudiment of the nerve remains.[4] [4] Just as the manuscript of this treatise was completed, a year and a half ago, we obtained at an autopsy a lung in which there was tuberculosis, but at the same time probably leprosy also. Most unfortunately the bronchial glands were not preserved for microscopical examination. Dr. Lie also permits me to state that he has found leprosy bacilli in two kidneys and in one lung. He had diagnosed tuberculosis of the lung, but at the autopsy he found only an indurating pneumonia, containing lepra bacilli, and no tuberculosis. In the kidneys, of the same case, he found lepra bacilli in the glomeruli, and in the interstices between the cortical tubules. He will describe the case more fully later. This is a mere preliminary note. CHAPTER IV. LEPRA MACULO-ANÆSTHETICA.