CHAPTER XLIIL 



SPORADIC DISEASES— continued. 



LOCAL DISEASES— continued. 



(F.) ADYEXTITIOUS SUBSTANCES m THE BR Am AND 

 CRANIAL CAVITY— CAUSING, GENERALLY, SYMP- 

 TOMS OF CONDITIONS VARIOUSLY TERMED SLEEPY 

 STAGGERS, IMMOBILITY, COMA, &c. &c. 



TUMOURS. 



Tumours are generally found in tlie choroid plexus. They are 

 very commonly met with in both plexuses, sometimes larger in 

 one than in the other ; very often quite symmetrical in size and 

 position. They grow slowly, and scarcely ever affect the health 

 of the animal, or give any indication of their presence, until they 

 have attained a size varying from a pigeon's to a hen's egg. 

 They consist of a caseous material, mixed with a calcareous 

 matter ; they are in fact composed of an exudation which has 

 undergone the caseous and calcareous degeneration. These 

 calcareous particles are called brain sand — psammoma — and 

 are never fonnd post mortem presenting signs of recent origin. 



I have found these psammomatous tumours in horses of various 

 ages, but most commonly in old horses. 



When they have attained the size above mentioned, they, in 

 some instances, give rise to severe convulsive fits, a staggering 

 gait and inability to perform work, whilst in others their pre- 

 sence is not indicated by any symptoms prior to a final stroke, 

 simulating apoplexy, to which the animal rapidly succumbs. 

 In those instances, when they occasion disturbance prior to the 

 fatal attack, the symptoms vary somewhat in character ; in one 

 animal there will be unconsciousness, with elevation of the head 

 and fore part of the body; in another — and this is rather a 



