ECHINOCOCCOSIS OF THE BRAIN, LUNGS, AND LIVER IN A HORSE. 



509 



haemorrhage had 

 substance of the 



On removing the brain the meningeal vessels appeared congested, 

 but it was not until the tissue had been hardened and carefully divided 

 that the most interesting lesion was discovered. Two typical cysts 

 were found : one about the size of a pigeon's egg in the upper part of 

 the cerebellum, rather inclined towards the left side ; the other, some- 

 what smaller, in the cerebrum. In both cases 

 occurred around the cyst, and had infiltrated the 

 brain. 



The cerebellar cyst had a distinct wall about one twentieth of an 

 inch in thickness, was lined by a greyish-white membrane, and con- 

 tained a yellowish caseous material, examination of which showed the 

 usual echinococcus spines. Around the cyst and extending obhquely 

 downwards and forwards towards the fourth ventricle was a well- 

 marked haemorrhage (see Fig. 71). The cyst in the cerebrum appeared 

 of later growth. Its wall was thinner and only perceptible with diffi- 

 culty. It contained a similar material, and was equally surrounded by 

 a hsemorrhagic area, which in this case, however, extended chiefly 

 upwards towards the point where the crucial fissure abuts on the third 

 anterior convolution. 



Note. — The cysts in the brain and cerebellum were apparently of 



Fig. 71. — Brain, showing cysts. 



considerable age, probably not less than two or three years, and pos- 

 sibly much older. That in the cerebellum might have existed for five 

 or six years, and provided its growth were slow have caused no peculiar 

 symptoms. Extensive tracts of the cerebellum can be destroyed by 

 malignant growths without interfering with even the most complicated 

 acts ; and it is known that in dogs, large portions of whose cerebellum 

 have been experimentally removed, function is sometimes completely 

 restored after the lapse of a year or two. It need excite no surprise, 

 therefore, that slowly increasing cysts in this region produced no sym- 

 ptoms calling for remark. 



Cysts, however, like tumours, are always surrounded by a network 

 of vessels, the walls of which are generally very thin, and which in an 

 old horse would be liable to rupture. A simple shock, such as that of 

 falling down when asleep, might produce this effect, especially if there 

 were a tendency to brain congestion, as occurs in acute indigestion. 

 (It must be remembered the horse had shown colic the evening before.) 



