This view, or something like it, continued to be the orthodox opinion at least up to the seventeenth century. Van Helmont’s personal experience of the itch is referred to in dealing with that eccentric genius who was converted from Galenism to Paracelsianism as a consequence of his cure; but he never got beyond the idea that the cause of the complaint was a specific ferment. The earliest really scientific contribution to the study of this disorder may be credited to Thomas Mouffet, of London, who, in a treatise published in 1634, entitled _Insectorum sive Minimorum Animalium Theatrum_, showed not only that the animalculæ were constantly associated with the complaint, but made it clear that they were not to be found in the vesicles, but in the tunnels connected with these. For this was the stumbling block of most of the investigators. It had been so often stated that the parasites were to be found in the vesicles, that when they were not there the theory failed. Mouffet’s exposition ought to have led to a correct understanding of the cause of the complaint, but it was practically ignored. About this time the microscope was invented, and in 1657 a German naturalist named Hauptmann published a rough drawing of the insect magnified. A better, but still imperfect, representation of it was given a few years later by Etmuller. In 1687 a pharmacist of Leghorn, named Cestoni, induced a Dr. Bonomo of that city to join him in making a series of experiments to prove that the acarus was the cause of itch. They had both observed the women of the city extracting the insects from the hands of their children by the aid of needles, and the result of their research was a treatise in which the parasitic nature of the complaint was maintained, and the uselessness of internal remedies was insisted on. These intelligent Italians recommended sulphur or mercury ointment as the essential application. Even with this evidence before them the doctors went on faithful to their theory of humours. Linnæus supported the view of Bonomo and Cestoni, but made the mistake of identifying the itch parasite with the cheese mite. The great medical authorities of the eighteenth century, such as Hoffmann and Boerhaave, still recommended general treatment, and a long list of drugs might be compiled which were supposed to be suitable in the treatment of itch. Among these, luckily, some parasiticides were included, and, consequently, the disease did get cured by these, but the wrong things got the credit. About the end of the eighteenth century Hahnemann promulgated the theory that the “psoric miasm” of which the itch eruption was the symptomatic manifestation, was the cause of a large proportion of chronic diseases.