DISEASES OF THE BRAIN. 477 



there are a variety of forms of staggers or convulsive disorders 

 due to functional or structural disturbance of the encepha- 

 lon. In the chapter on Impaction of the Stomach in the 

 Horse, at page 186 of the first volume of this work, I have 

 drawn attention to the forms of staggers due to gastric 

 derangement, and have described three kinds. One is 

 characterised by delirium, a second by coma, and a third by 

 interference with the voluntary muscles. The symptoms 

 connected with these forms of stomach staggers are simi- 

 lar to convulsive attacks due to cerebral diseases of various 

 kinds such as I have to notice in the following pages. I wish 

 now to draw special attention to Megrims, the staggers of 

 horses at work, and which has been mistaken for epilepsy. 

 Mr Percivall says, " By Vertigo, as synonymous with 

 Megrims, I do not mean any simple or single symptom of 

 giddiness which a staggered horse may evince ; but I mean 

 an assemblage of vertiginous symptoms which suddenly 

 attack, and as suddenly disappear after the manner of a fit, 

 and to which horses all their lives may be at times subject, 

 and yet never experience what we understand by staggers, 

 i,e., encephalitis, or phrenitis, or even coma. This makes 

 me say megrims is a disease mi generis, though of what 

 precise or definite nature, I am not at present prepared to 

 give an opinion." In this paragraph which I quote from the 

 Hippopathology, there are two errors. The one is attributing 

 ordinary staggers to inflammation, and the other is regarding 

 megrims or vertigo as a specific disease. That Mr Percivall, 

 like all other authors who have written on megrims, has 

 known nothing about the disease, is proved not only by his 

 words to the effect that " the pathology of megrims remains 

 undeveloped," but by his statement as to the causes of the dis- 

 ease. He says, " high or full condition, hot weather, exertion 

 or agitation of any kind, may be said to be likely to produce 



