354 CHRONIC DISEASES OF THE CEREBRAL STRUCTURES. 



is slightly variable ; usually they are composed in greater part 

 of the fatty material cholcsterine, arranged in plates closely 

 packed in layers, combined Avith amyloid or starch-like bodies, 

 a very limited amount of serum and fine connective-tissue ; 

 the greater part of this latter being disposed of as an investing 

 capsule. 



These abnormal growths develop rather slowly, probably 

 appearing first as simple hypertrophy of the villi of the 

 plexuses, and, although they may attain a considerable size, 

 they do not often, under ordinar}^ conditions, cause much in- 

 convenience. 



Symptoms. — While some of these growths are injurious in 

 virtue of and as part of the operating agency of a general 

 diseased condition, the greater number appear to injure more 

 from the alteration Avhich their presence induces in the sur- 

 rounding portions of the bram-structure, while it is un- 

 doubtedly certain that several, as those of the choroid plexus, 

 may exist for a lengthened period without entailing any 

 obvious disturbance. Violent or great exertion in all animals 

 in which these tumours exist is liable to be attended with 

 cerebral disturbance — uncontrollable excitement, impairment 

 or loss of consciousness, and control over voluntary movement, 

 similar to what occurs during fits of megrims from cerebral 

 congestion. 



Treatment. — The management of these cases w^ith a view to 

 ultimate recovery is of course hopeless, but with careful treat- 

 ment of animals so affected and the judicious apportioning of 

 their work, making it gradually progressive in severity, very 

 satisfactory results may sometimes be obtained. 



III. Hydrocephalus — Dropsy of the Brain. 

 Hydrocephalus, or a collection of fl.uid Avithin the ventricles, 

 in or beneath the arachnoid, or in both situations, although 

 usually appearing as a congenital disease, ma}^ be developed at 

 any period of the animal's life. The consideration of this 

 affection is of less importance to the veterinary surgeon than 

 the practitioner of human medicine, as well from the compara- 

 tive rarity of its occurrence in our patients as from the acknow- 

 ledged futility of its treatment when present. Congenital 

 hydrocephalus is to us chiefly interesting from two considera- 

 tions : first, the apparent connection which seems to subsist 



