25G 
ON HYDROCEPHALUS 
aggravate the malady already existing; being in itself a fresli source of 
pain, and consequently augmenting that already ])resent, inasmuch as 
the diseased part naturally responds to pain from other quarters. This 
sympathy does most certainly exist when the brain is the seat of disease 
—itself the common and prolific centre, both in health and disease, of 
all the sensations/^ 
‘‘Vlll. Furious delirium, extreme agitation, convulsions and spasms, 
indicate, generally speaking, in these affections, that the membranes in 
particular, and above all the arachnoid, are the seat of disease ; whilst 
stupor, coma, collapse, lethargy, muscular debility, &c. belong more 
especially to those cases in which there is alteration of the proper sub¬ 
stance of the brain. In the above case, the alternation of furious de¬ 
lirium and lethargy showed, as was afterwards proved on dissection, that 
the brain and its membranes were both aflected at one time, and that 
encephalitis, which preceded, became subsequently complicated with 
arachnoiditis, inasmuch as the symptoms of the latter did not make 
their appearance until after the manisfestation of those of the former 
aftbction/’ 
Examination ,—Appearances within the chest and abdomen 
analogous to those in the preceding cases. Ventricles commu¬ 
nicating one with another^ and containing about six ounces of 
limpid fluid. 
Case IV. A horse belonging to the royal stables was sud¬ 
denly attacked, in the summer of 1817, with a veiy violent irri¬ 
tation of the membranes and brain, having frequent paroxysms 
of frenzy, alternating with a state of lethargic stupor, of which 
he died in three days, in spite of repeated blood-lettings, the 
continual application of cold to the head, and the employment 
of derivatives. We found traces of chronic inflammation of 
the intestinal canal, the lungs gorged with blood, and the ven¬ 
tricles containing a very large quantity of limpid serous fluid. 
GENERAL CONSIDERATIONS ON HYDROCEPHALUS. 
Hydrocephalus, or, more properly, morbid irritation of the 
brain and its membranes, to which it is pathologically owing, is 
among horses the most'frequent of cerebral disorders. In the 
acute fomi, it often gives rise to the affections called phrenzy, 
and to vertigo, idiopathic or symptomatic, which are confounded 
with actual inflammation. In the chronic fonn, it produces 
sleepiness, coma, lethargy, chronic vertigo, immobilityj and 
sometimes also epilepsy. If it be but slight, it shows itself in 
momentaiy tits of drowsiness, stupor, and ybrenzy, 
“IX. In regard to immobility, it is not quite certain that it consists in 
disorder of the brain any more than it is an affection of the spinal 
marrow or its arachnoid covering.’^ 
“X. And in respect to symptoms of agitation or collapse (peruse 
again Annot. VIII. p. 252) the remarks already made are founded u})on 
facts resulting from observation, and I repeat here, that such symptoms 
no more belong to the acute than to the chronic form of disease; but 
that the former, viz, those of exaltation, denote that the membranes are 
