Meningo — Encephalitis. Staggers. 103 



Even in these there is left an increased predisposition 'to re- 

 currence. It is noted by Trasbot that the mortaUty is higher in 

 highbred, nervous, irritable animals, which show a tendency 

 to greater frequency, force and duration of the paroxysms of ex- 

 citement. When decubitus is constant, death may take place 

 from septic poisoning starting from bed sores, and gangrenous 

 sloughing. In other cases there is fatal starvation from inability 

 to eat. 



Lesions. In pachymeningitis due to mechanical injury there 

 is usually cutaneous and subcutaneous, blood extravasation, and 

 there may be fracture of the cranial bones. The dura matter is 

 dark red, hyperaemic, thickened, covered with exudation and small 

 blood clots mixed with pus cells, and has contracted strong ad- 

 hesions to the cranial bone. Bony spicula may project into the 

 fibrous neoplasm. 



Leptomeningitis usually coexists from extension of the in- 

 flammation into the adjacent arachnoid and pia mater. There 

 is then a reddish serous effusion into the arachnoid and beneath 

 it, and the substance of both membranes is thickened by exudate, 

 and discolored by congestion and minute haemorrhages. When- 

 ever the pia mater is thus inflamed, the superficial layer of the 

 brain is implicated, oedematous, soft and doughy. The exten- 

 sion is also made into the ventricles and a serous effusion takes 

 place often to two, three or more times the normal amount 

 (82 grammes, Schiitz) . The choroid plexus forms a yellowish 

 gelatinoid mass, and the ganglia (corpora striata, optic thalamus, 

 etc.), are flattened. 



In encephalitis the affected superficial gray matter of the 

 ganglia or convolutions, is deepened in color, usually in limited 

 areas corresponding to the disease of the meninges. Sometimes 

 the color becomes of a distinctly reddish tinge, and, when cut into, 

 shows unusually prominent red points where the capillaries have 

 been cut . Somewhat larger areas of blood staining indicate hsemor- 

 rhagic extravasations. The nervous substance is more or less 

 infiltrated with liquid and softened. The nerve cells are swollen, 

 and in process of granular degeneration and the same is true of 

 the myelin, while the axis cylinder is uneven in its outline. 

 Apart from the numerous minute petechial haemorrhages there is 

 an abund.ant migration of leucocytes which are found scattered in 

 the degenerating and softened nervous tissues. 



