The nature of paralysis agitans has been an attractive subject for investigation ever since the publication of Parkinson's1 celebrated "Essay on the Shaking Palsy" a century ago.
Many strange theories have been advanced and innumerable lesions suggested in explanation of the peculiar phenomena of this interesting disease. But as our knowledge of the pathology and physiology of the nervous system has advanced, many hypotheses, at one time popular, have been discarded and now have only an historical interest. That the subject, however, is still shrouded in uncertainty and mystery, may be readily determined by a perusal of the more recent descriptions in authoritative textbooks of medicine and neurology.
In former years paralysis agitans was described by some authors with the functional diseases, while others believed it to be an affection of the muscular system. It has been held more recently to be related to certain of the ductless glands and