416 CHOREA. 



in the possession of its then owner for a few Aveeks. On 

 examination after death, along with other thoracic compUca- 

 tions, the pericardium showed much structural alteration, 

 apparently the result of acute inflammatory action. The chief 

 factor in the development of this nervo-muscular disturbance 

 in the equine sufferer seems hereditary predisposition. If not 

 born with the disease visibly manifest, the ultimate sufferers 

 seem at least to have inherited the tendency to develop it very 

 early in life and under very trivial causes. Apart from this 

 congenital tendency, adverse influences, as overwork, defective 

 sanitation, and improper dietary, exert a very trifling and 

 merely secondary power. When established, they undoubtedly 

 tend to its aggravation. 



Whether in all these forms of nervo-muscular disturbance 

 spoken of as choreic the immediate cause is to be looked for 

 in change in the nerve-centres or nerve-cords, or whether the 

 different manifestations have separate and varying lesions 

 upon which they are dependent, it is, with our present know- 

 ledge, impossible definitely to affirm. 



To me it seems more in accordance with fact and observa- 

 tion to regard the seat of the change or disturbance in those 

 more truly choreic manifestations in the horse spoken of under 

 the term of ' shivering,' and other names taken from the more 

 attractive symptoms, as located in the cerebral ganglia rather 

 than in the cord. In these instances the spasms are not con- 

 tinuous, which it is probable they would be if the cord alone, 

 or chiefly, was the seat of textural change. Also we find 

 that the muscular aberrations are alwaj'-s disposed to develop 

 themselves whenever will is put forth to execute movement, 

 excitation seeming to spring from the cerebral rather than the 

 cord-centres. Other nervo-muscular disturbances confined to 

 individual muscles or groups of muscles, chiefly of the limbs, 

 such as ' string-halt,' which, in default of more perfect know- 

 ledge, we are content still to regard as in their nature choreic, 

 may, with less danger of error, bo regarded as dependent on 

 particular interference with functional activity either of the 

 peripheral nerves or of the cord-centres. 



Anatomical Characters. — After-death examinations, both of 

 men and animals, although disclosing morbid conditions 

 common to several diseases of the nervous system, do not 



