Since 1817, when James Parkinson5wrote on the Shaking Palsy, bits of information have been accumulating concerning this disorder. The epidemic of lethargic encephalitis during and after World War I contributed to the development of the concept of the Parkinson syndrome. Today many combinations of tremor, muscle rigidity, and weakness are termed parkinsonism, whether they be Parkinson's original paralysis agitans or the types associated with lethargic encephalitis or appearing during the arteriosclerotic age (whatever that be), or those rarer forms following on trauma, toxin, or tumor. Walshe5had this to say about these syndromes: "When all is said, it may be admitted that the tremorrigidity component is essentially the same in all Parkinsonian syndromes, but the illnesses in which this component is found are clinically distinguishable in most if not all instances, in virtue of other components found in one or another aetiological variety, and in virtue of