Arning has described a miliary leprosy, and found in the products of this disease giant cells, and also leprous ulcers in the intestines. Dr. Arning has kindly sent us some preparations of this miliary leprosy, in which we find evidence everywhere that the case is one of tuberculosis, both because giant cells are found everywhere, and the bacilli are only present singly, and scattered. They are never present in the excessive numbers, and have not the arrangement, which they usually have in leprous products. In connection with the presence of giant cells in leprous products, we may note that we have received from two foreign colleagues preparations in which they believed giant cells to be present. But we have found, on careful examination of the preparations, that they were cross and oblique sections of blood vessels, which with their endothelial nuclei gave the impression of giant cells. Without the use of a homogeneous immersion lens it was not possible to make a definite distinction. According to our observation there exists a sharp anatomical distinction between leprosy and tuberculosis, and there is no such thing as leprosy of the lungs and intestines, the bones and the kidneys. In order to establish a differential diagnosis in doubtful cases, we recommend in the case of the lungs and the intestines a thorough examination of the bronchial and mesenteric glands. We ourselves have never sought in vain, in cases of these affections, for tuberculous or caseous degeneration in the glands, and we have seen in no single case anything resembling leprous affection of the glands. So far as concerns the central nervous system, Danielssen noted that he had several times seen acute hydrocephalus in leprosy. We once saw severe cerebral symptoms with maniacal attacks. The patient, who was taken into a lunatic asylum, left this later, cured. Other indications of an affection of the central nervous system in leprosy are unknown to us. Anatomically, we have not been able to recognise in the nervous system any traces of leprosy. In connection with this, we may note that we have several times seen pain and swelling of the knee joints during eruptions, which at their conclusion disappear. In these cases there is nothing to be made out anatomically. When we reflect that, as indicated in describing the eruptions, the bacilli and (or) their toxines most probably circulate for some time in the blood, it is remarkable that the organs above referred to are not affected by leprosy. We can give no reason for this; connective tissue, which is especially liable to be affected, is present everywhere. CHAPTER III. STRUCTURE OF THE LEPROMA.