322 
DIAGNOSTIC SIGNS OF ABSCESS. 
substance by which the cyst is environed becomes irritated and 
inflamed, and then symptoms are evinced of the existence of ab- 
scess or other serious lesion of the organ. Therefore it is upon 
the inflammation and irritation of the brain produced by the pre- 
sence of the collection, and in proportion to their degree, that the 
manifestations of the lesion depend. 
It is in the functional derangement of the brain that we are to 
look for the symptoms of abscess existing in that organ. These 
functions consist of intelligence, instinctive desires, volition, and 
sensation. In this series of manifestations the phenomena of the 
disease must be sought after ; and, according to the intensity, seat, 
particular state, progress, and extent of the organic change, the 
symptoms will vary. There are, which these manifestations indi- 
cate, not the acute forms of cerebritis and meningitis, but the sub- 
acute or chronic state of these lesions, differing from the former in 
the less intensity of the symptoms and the slower progress of the 
disease. Cerebritis may be general or partial. Of the latter is 
the particular state indicating the existence of abscess. In the 
horse and other animals the early or first symptoms generally pass 
over unnoticed. The sensibility of the surface and the action of the 
muscles, while partially and not permanently affected, and also the 
moderate degree of disturbance of the instinctive, or perhaps, more 
correctly, intellectual faculties, are seldom observed. Paralysis 
consequent on pressure, and disorganization, obscure the spastic 
contractions attending the early inflammatory irritation. 
The first symptoms which attract the attention of the owners of 
horses in these cases are generally vertigo, dulness and defective vi- 
sion. The animal reels in his walk, stands with his legs Avide apart, 
and appears heedless of Avhat is passing around him. In some cases, 
at this period, both the respiration and the pulse are moderately 
increased, while in others they are tranquil, or the latter increased 
in force only. If the purulent collection approaches or extends to 
the periphery of the brain, and the membranes are involved in the 
consecutive irritation, there is a tendency to delirium either inof- 
fensive, morose, or furious. About this period, should the disease 
be confined to one hemisphere, the opposite side of the body gene- 
rally indicates the principal derangement, in the spastic contractions 
of the muscles, the partial paralysis of the limbs, and, as I have 
more than once observed, a difference in the size of the pupils. 
As the disease advances, the organs supplied with the ganglial 
nerves are rendered more torpkl — the pulse is slow and oppressed 
— the breathing deep, and occasionally stertorous, and there is som- 
nolency, lethargy, and coma. In other instances, there is more of 
furious delirium — the eyes are Avild and staring, and the pupils di- 
lated to blindness. If copious bleeding is practised at this period of 
