Unfortunately, all attempts to inoculate animals have failed. The now old experiments of Neisser and Damsch, as well as our own, we may pass over. We dealt with them in our Copenhagen communication. Since then Melcher and Ortmann believe that they have communicated the disease to rabbits. Dr. Ortmann has kindly sent us preparations from the infected rabbits, and on close examination of them we regret to say that we lost our faith in the leprous nature of this affection of rabbits. We found both caseous degeneration and myelo-plaques in the preparation, which, as we have noted, we have never found in leprosy. At the same time the affection does not look exactly like tubercle, and it is possible that in rabbits leprosy appears otherwise than in man. But we may note that Veterinary Surgeon Nielsen has, here in Bergen, observed a disease in mice, which shows a close resemblance to Ortmann’s rabbit leprosy. Inoculated on a rabbit, the disease appeared with new growths in the cœcum, just like Ortmann’s rabbit leprosy. These new growths had certainly more resemblance to tuberculosis; but there were in them, at many places around the vessels, cells, crammed full of bacilli. Nielsen’s investigations are not yet concluded, but it is possible that the disease is one of animals as yet unknown, which Melcher and Ortmann have by chance conveyed to their rabbits. All the inoculations of leprosy on rabbits which Dr. P. F. Holst made in the laboratory of the Lungegaards Hospital were unsuccessful; not one of the infected animals became leprous. Although, as we have stated above, the lepra bacillus has never been found outside the human body, this might possibly be dependent on insufficient search, and it might be possible that the old view at present maintained by Hutchinson is the right one, viz., that leprosy is caused by the eating of putrifying fish, or that the contention of Holmsen that leprosy is a miasmatic disease, is correct. Against Hutchinson’s hypothesis there is in the first place the fact that we have never succeeded in cultivating the bacillus, which, if the bacillus lived as a saprophyte on decaying fish, would be a very simple matter. And there are, secondly, places where the inhabitants certainly and frequently enjoy decaying fish without the disease appearing. And thirdly, there are many places authoritatively indicated where leprosy is present, and where no fish is ever eaten. For his hypothesis of the miasmatic origin, Holmsen can only bring forward the fact that the disease is often limited to certain districts. This is certainly correct, but this endemic appearance of leprosy may be as readily explained by infection, while the localities affected do not give the slightest support to the assumption of a miasma. Such areas are found here in Norway, both on the bare cliffs, on the coast, in the valleys, and on the mountains.