152 ANNUAL REPORT OP THE Off. Doc. 



pillary hemorrhagic extravasation of the cortical and sub-cortical 

 tissues, tumor formation due to proliferation of elastic tissue of 

 the choroid plexus of the lateral ventricles. 



The ganglionar lesions above described closely resemble those 

 described bv Van Gehuchten and N^lis in rabies. In rabies, how- 

 ever, there is an active proliferation of the capsular cells with a 

 marked tendency to extension within the capsule, while, as has 

 already been pointed out, the tendency in this disease is to a peri- 

 capsular accumulation of cells. In advanced cases of forage pois- 

 oning the ganglion cells may entirely disappear and an accumulation 

 of small round cells remain. Under these circumstances the picture 

 cannot be differentiated from rabies by an examination of the 

 ganglion alone. The perivascular round cell accumulation in the 

 pons and medulla, which is rather constant in rabies, is never 

 present in forage poisoning. There is no degeneration of the peri- 

 pheral nerves in rabies. The clinical course of the two diseases 4s 

 entirely different, and there should be no diificulty in separating 

 the two conditions by the pathological lesions. 



Professor Van Gehuchten, of Louvain, to whom we submitted 

 the specimens from our first case (a calf), confirmed our opinion 

 that there was a distinctive difference between the ganglionar 

 changes in forage poisoning and in rabies. 



Concerning the specimen sent to him he writes: '"It cannot be 

 denied that there is a sensible proliferation of the cells of the en- 

 dothelial capsule, but this proliferation does not, however, appear 

 to me to be as intense as in cases of rabies; so much so, that I 

 would not make the diagnosis of rabies from the examination of 

 the sections alone. I do not think that this animal had rabies. 

 Rabies excluded, there remains a certain amount of proliferation, 

 the cause of which escapes me; but in my opinion the degree of 

 proliferation cannot be compared with that which occurs in rabies." 



CONCLUSIONS. 



1. The so-called epidemic cerebro-spinal meningitis of horses is 

 not a true meningitis, and presents neither the gross nor micro- 

 scopic lesions of true meningitis. 



2. The evidence goes to show that all epidemics are caused by 

 some poisonous substance contained in the forage. This is proven 

 conclusively in the epidemic mentioned above, and in the experi- 

 ments of Dr. Pearson. 



3. The lesions in the intervertebral ganglia so closely resemble 

 those described by Van Gehuchten and N^lis in rabies, as to offer 

 the presumption that the pathological process in the two diseases 

 is somewhat similar. 



