Chronic Hydrocephalus. Dropsy of the Ventricles. in 



Caiises. Acute encephalitis may lapse into the chronic form and 

 then assumes the symptoms of this disease. Cases that come on 

 slowly and imperceptibly appear at times to be hereditar}-, as 

 might be expected from the fact tliat it usually goes with a 

 lymphatic temperament. The conditions which cau.se cerebral or 

 meningeal hypergemia in chronic form conduce to the affection. 

 Injuries to the cranial vault from traumatism or disease are infre- 

 quent causes. Renault records a case associated with two bony tu- 

 mors, each as large as an egg, projecting inward from the frontal 

 bone and which had produced extensive absorption of the convolu- 

 tions and increase of the cerebro spinal fluid. In a case of my 

 own with an abscess in the diploe above the frontal sinus, and 

 pressing inward on the brain a similar condition existed. In 

 other cases Renault noticed that the cerebro spinal fluid was 

 largel}' in excess. 



Much more commonh', however, the accummulation of liquid 

 takes place in the ventricles, and is associated with different 

 causes : as tumors or false membranes near the base of the brain 

 pressing on the veins returning blood from the ependyma, tumors 

 in the ventricles (cholesteatomata, etc., of the ependjana or 

 choroid plexus) obstructing the circulation or giving rise to local 

 hyperaemia, and chronic congestions from the other cau.ses such 

 as faulty conditions of fodders, or water, exposure to undue heat, 

 overwork, etc. The enzootic prevalence of the disease in certain 

 localities, (Alps, Rhone Valley, bottom lands) would suggest that 

 local conditions in food or water are factors, though we cannot as 

 yet fully explain the mode of causation. In the .same way we 

 must recognize the influence of hepatic and gastric disorders, 

 which arise from such fault}' regimen and affect the brain by 

 nervous sympathy and by the action of toxic elements thrown 

 into the circulation. Then again we must take sufficient ac- 

 count of the congestions resulting from obstructions in the 

 lesser circulation, di-sease of the lungs, and of the right heart, 

 and compression of the jugulars by a tight or badly fitting 

 collar, or compulsory curving of the neck as set forth under 

 vertigo and cerebral congestion. 



Symptoms. Among the symptoms must be recognized the 

 conformation with which it is usually found associated. The 

 predisposed animals are usually low bred, common horses, with 



