5l6 CKREBRO-SPINAL MENINGITIS 



system and other organs that could be detected by a gross 

 examination. In one case the brain, spinal cord, and organs 

 were studied histologically with like results. 



MacCallum and Buckley have found in the brains of 

 horses dying of this disease areas of softening " in the frontal 

 region on each side, anterior to the motor region of the 

 cortex." This lesion was practically confined to the white 

 matter immediately under the cortex. In the affected areas 

 there was "complete destruction of the brain substance, in 

 which the anatomical structures are disintegrated and largely 

 replaced by a colloid-like material ". The neighboring blood 

 vessels were acutely inflamed, with exudation of leucocytes 

 and passage of red corpuscles into the peri-vascular lymph 

 sheath and adjacent tissue. In a later epizootic they failed to 

 find the brain lesion but did detect the vascular changes. 



McCarthy and Ravenel in a study of fifteen animals found 

 certain lesions in the upper gastrointestinal tract and in the 

 central nervous system. These were'(i) in the intervertebral 

 and Gasserian ganglia where a peri-capsular, small round cell 

 accumulation was present. The cells were all of the same 

 type, the nucleus and protoplasm being about the size of a red 

 corpuscle. There was no evidence that these cells were the 

 result of proliferation of the original layer of capsular cells. 

 (2) Cortical lesion. These consisted of congestion of the 

 cerebellar and cerebral cortex. There were also capillary 

 hemorrhages. The meninges were normal. (3) Changes in 

 the choroid plexus. In three cases the choroid plexus was 

 changed into a triangular, tumor-like mass, of a yellowish red 

 color and of a firm consistency. . The increase in size was 

 found to be due to a proliferation of the elastic tissue sur- 

 rounding the vessels. (4) Changes in the peripheral nerves. 

 There was a distinct degeneration of the nerves supplying the 

 larynx and neck. This was present in the nerve up to the 

 ganglion, but was not found in the posterior roots. Other 

 slight changes were detected. 



These authors conclude that this disease is not a true 

 meningitis, but that the evidence goes to show that it is caused 



