DISEASES OF THE NERVOUS SYSTEM. 215° 
of diseased cerebral arteries and of apoplexy. The symptoms are 
drowsiness, vertigo, or attacks of giddiness, increased timidity, or 
fear of familiar objects, paralysis of one limb, hemiplegia, imperfect 
control of the limbs, and usually a weak, intermittent pulse. In some 
cases the symptoms are analogous to those of apoplexy. The char- 
acter of the symptoms depends upon the seat of the softening or 
abscess within the brain. 
Cerebral sclerosis sometimes follows inflammation in the structure 
of the brain affecting the connective tissues, which eventually become 
hypertrophied and press upon nerve cells and fibers, causing their 
ultimate disappearance, leaving the parts hard and indurated. This 
condition gives rise to a progressive paralysis and may extend along 
a certain bundle of fibers into the spinal cord. Complete paralysis 
almost invariably supervenes and causes death. 
Lesions—On making post-mortem examinations of horses which 
have died in the first stages of either of these diseases we find an 
excessive engorgement of the capillaries and small blood vesséls, with 
correspondingly increased redness and changes in both the contents 
and the walls of the vessels. If death has occurred at a later period 
of the disease, it will be found that, in addition to the redness and 
engorgement, an exudation of the contents of the blood vessels into 
the tissues and upon the surfaces of the inflamed parts has super- 
vened. If the case has been one of encephalitis, there will usually 
be found more or less watery fluid in the ventricles (natural cavities 
in the brain), in the subarachnoid space, and a serous exudation be- 
tween the convolutions and interstitial spaces of the gray matter un- 
der the membranes of the brain. The quantity of fluid varies in 
different cases. Exudations of a membranous character may be 
present, and are found attached to the surfaces of the pia mater. 
In meningitis, especially-in chronic cases, in addition to the serous 
effusion, there are changes which may be regarded as characteristic in 
the formation of a delicate and highly vascular layer or layers of 
membrane or organized structure on the surface of the dura mater, 
and also indications of hemorrhages in connection with the membra- 
nous formations. Hematoma, or blood tumors, may be found em- 
bedded in this membrane. In some cases the hemorrhages are copious, 
causing paralysis or apoplexy, followed by speedy death. The menin- 
gitis may be suppurative. In this case a puslike exudate is found 
between the membranes covering the brain. 
In cerebritis, or inflammation of the interior of the brain, there 
is a tendency to softening and suppuration and the formation of 
abscesses. In some cases the abscesses are small and numerous, sur- 
rounded with a softened condition of the brain matter, and some- 
times we may find one large abscess. In cases of recent development 
