until retirement. He was struck by an undetermined disease of the central nervous system (perhaps a tumor or intracranial hematoma) that caused seizures, a right hemiparesis, and progressive mental deterioration. He was attended to by his most trusted colleagues and his old master Vallisneri. Pacchioni died in Rome at 62 years of age. Thoughts and works Despite his extreme versatility, Pacchioni is best known as an anatomist and a skilled dissector. He made significant contributions to the elucidation of the structure and function of dura mater, investigating its fine structure. Following Malpighi's teachings, he made use of the microscope, an advanced technology of his time, and systematically treated the anatomical specimens by original techniques of maceration into "... strong, sour, salted, sweet, and oily fluids .... ". For example, in the Dissertatio Epistotaris..., Pacchioni pointed out how arachnoid villi swell "... to the size of a millet seed... " after dura is "...soaked for a month first into plain water and then into vinegar..." (recommending frequent renewal of the bath in order to avoid smell!) The interpretation of Pacchioni's morphological findings was adversely influenced by his adherence to the "iatromechanical doctrine," whereby the function of an organ was merely based on its mechanical activity. Therefore, he believed that dura mater was a special kind of membranous muscle ("musculus suigeneris membranaceus"), comparable to cardiac muscle, made up of several layers of fibers and arranged in three bellies and four tendons; its contractions served to squeeze the glands which, in Malpighi's opinion, constituted the cerebral cortex, pushing their secretion along nerve roots? Among Pacchioni's findings, we recall the description of the tentorial notch (the so-called "Pacchioni's oval foramen"), the observation that dural adherence to the inner table is variable in different areas, and especially the discovery of arachnoid granulations. In 1705, Pacchioni dedicated to Professor Luca Schrok (a German colleague from Augsburg) the Dissertatio Epistolaris de Glandulis Conglobatis Durae Meningis Hurnanae, indeque Ortis Lymphaticis and Piam Meningem produclis. One of his popular papers is written in Latin and illustrated with two figures and remarkable for its scientific rigor, careful report of materials and methods, and frequent quotation of up-to-date international literature. While exploring the internal structure of the superior sagittal sinus, Pacchioni was struck by those minute globular bodies (which he named "glandulae conglo-batae"), each wrapped by its own capsule, clustering on either side of the sinus. Numerous thin filaments, which he