12 STAGGERS. 



or less violence, and has been partial or general. The plexus 

 choroides, too, are often found turgid with blood. Though this may 

 be said to constitute the ordinary state of the brain of the horse 

 dying of encephalitis, yet it is right we should observe that several 

 other anormal appearances have been recorded as connected with 

 mad staggers, and on authority which we have no reason to call 

 in question. 



Softening of the BrMN is by no means an uncommon 

 result of inflammation in it, but, I believe, rather of that in a 

 chronic than an acute form. Rarely, I believe, is the cerebral 

 substance found indurated or firmer than natural. 



Discolouration. — In one instance I met with a remarkable 

 yellowness of the cerebellum ; the horse having at the same time 

 considerable disease of the liver. Were the two alterations patho- 

 logically connected ? Mr. Field mentions a case of discolouration 

 of the corpora striata and septum lucidum. 



Purulent Matter will form under active inflammation. 

 Mr. Field gives an account of a case in which a large abscess ex- 

 isted in the posterior hemisphere. 



Albuminous Matter. • — The same respected authority has 

 left us the relation of another casein which thick layers of coagu- 

 lable lymph were found in the lateral ventricles completely coating 

 the thalami nervoreum opticorum. 



ARAGHNOIDITIS. 



In cases in which the seat of inflammation may be pronounced 

 to be membranous, we learn, from the closest pathological exa- 

 minations, that the arachnoid membrane is in particular affected, or 

 affected to that supereminent degree to warrant us in charac- 

 terising the disease as arachnoiditis ; and as we have French 

 veterinary authority for considering this as the most frequent 

 proximate cause of staggers, perhaps it would be advisable here to 

 transcribe from the same authority — M. Roupard — the account 

 given of arachnoiditis. It is published in the Compte Rendu for 

 the year 1825 of the Veterinary School at L3^ons. 



]M. Roupavd lays it down as established, that acute idiopathic arachnoiditis 

 hasits origin in lesion of the' arachnoid membrane, the consequence of cerebral 



