GENERAL CHARACTERS. 385 



function are sufferers equally, or at least proportionately with 

 the extent to which they are dependent for their nerve-supply 

 from the same centre, with other organs, as those of locomotion, 

 which are more visibly disturbed. 



In examining this matter, it may be noted as a somewhat 

 curious circumstance, if the true cause of this enzootic para- 

 plegia is feeding on specially conditioned rye-grass, that this 

 peculiar disturbance of innervation should only show itself in 

 the horse. In the explanation of this immunity many facts 

 and circumstances require to be taken into consideration. 



Both cattle and sheep are sufferers from disturbed innerva- 

 tion connected with dietetic causes, and largely from feeding 

 upon grasses in particular conditions of growth and during 

 certain seasons of the year ; and although some seem to regard 

 these morbid states in ruminants, marked by characteristic 

 symptoms, as precisely similar to this disease which we are 

 now considering, I am rather doubtful of such similarity. 

 Acute diseases of these animals intimately associated with or 

 resulting from dietetic causes, are all, or nearly all, apparently 

 referable to changes in connection with the cerebral part of 

 the system, and paraplegia alone is not a diagnostic feature of 

 them. It must be remembered that cattle as a rule are rarely 

 placed on these particular pastures — the young grasses or seeds, 

 as agriculturists term them — where this disease exhibits itself 

 in horses : they are generally alloted older and rougher graz- 

 ings, while, when they may be located where rye-grass is 

 abundant, they feed in a very different manner. The horse is 

 disposed to top the grass, to eat the flowering stems almost 

 entirely to the exclusion of the foliage of the plants ; the ox 

 has the opposite taste, and crops both foliage and seed-stem, 

 while if he seems to have a preference it is for the leaves, not 

 the stems of the grasses. 



In the case of sheep, again, they rarely crop the flowering 

 or seed-stem, but keep closely to the root foliage. While it 

 ought to be remembered that ruminants of all kinds seem to 

 have a greater power of resisting the poisonous influence of 

 most vegetable substances than solipeds. 



h. Causation. — The characteristic feature of the disease, the 

 impairment or loss of power of voluntary movement in the 

 organs of locomotion, particularly of the posterior extremities, 



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