Among other alleged causes of chorea is embolism of the arteries of the brain or spinal cord. Angel Money went so far as to inject a fluid containing arrowroot, starch granules and carmine into the carotids of animals, and produced movements closely resembling those of chorea. Another theory connects chorea with the rheumatic poison. Some English writers find more than 80 per cent. of all cases in man associated in some way with rheumatism, but in Philadelphia, Sinkler found that not more than 15 pet cent. showed such a relation. D. C. Wood as the result of necropsies of a number of choreic dogs reached this conclusion: “Owing to emotional disturbance, sometimes stopping of various vessels of the brain, or sometimes the presence of organic disease, there is an altered condition of the ganglionic cells throughout the nerve centres. If the cause is removed and the altered condition of the nerve cells goes only so far, it remains what we call a functional disease. If it goes so far that the cells show alteration, we have an organic disease of the nervous system.” In man the element of sudden fright is awarded a high position in the list of causes. _Lesions._ Constant morbid changes of structure have not been established in chorea. On the contrary in the many careful necropsies of choreic subjects some lesion of brain or spinal cord has been almost always found. Dickinson always found congestion of some part of the brain or spinal cord, but most constantly of the substantia perforata, the corpora striata and the beginning of the Sylvian fissure. In the cord the cervical and dorsal regions were the most commonly affected, and preëminently the gray matter at the root of the posterior horn. The bilateral symmetry of the contractions in cases of unilateral lesions, has been held to discredit the theory of embolic origin, yet this may be explained by mutual relation of the ganglia of the two sides and their coördination of function. The question of the relative importance of the encephalic and spinal lesions has been also debated. Chauveau believed that by section of the cord in choreic dogs, he had proved that the spasms were of medullary origin. Wood on the other hand found that the choreic movements persisted after section of the cord, and seemed warranted in the conclusion that the movements originated in the cord. The probability is, that with the cord intact, the primary source of the morbid movement may reside either in the encephalon or the cord. In chorea, following distemper, I have found marked congestion of the encephalon and its meninges.