COMPRESSION ON THE BRAIN. 577 
healed of its own accord. In April 1818, however, instead of 
the tumour, the horse exhibited symptoms of intense vertigo, 
which disappeared in eight days, after copious bleeding and pur¬ 
gatives, and the local application of cold. In April 1819, he 
was again attacked with vertigo, and exhibited the following 
symptoms :—he carried his head low, and always inclined to the 
right side; he staggered as he walked, and the motion of his 
limbs was marked by a peculiar convulsive action, confined, how 7 - 
ever, to the fore extremities: he moved by a succession of spas¬ 
modic boundings ; he was completely deaf, and rapidly lost flesh, 
although he ate and drank voraciously. 
He remained in this state until the month of November, when 
all the symptoms, except the deafness, sensibly diminished ; and 
so he continued until the 3d of January, 1820, when he expe¬ 
rienced a fresh attack of vertigo, and died suddenly. On ex¬ 
amination after death, the following lesions presented themselves. 
The dura mater and arachnoid membrane were red over the whole 
of the superior and anterior portion of the brain. On the septum 
medium (called by our writers the septum lucidum), and to¬ 
wards the posterior part of it, was a round cyst fixed between 
the two cerebral lobes. It was about the size of a pullet’s egg ; 
its parietes were thickened, and of a fibrous character, and it 
contained a homogeneous, yellow, viscid fluid. It adhered by 
its anterior portion to the septum medium, and by its superior 
part to the ridge of the parietal bone; and it was attached to 
both by dense and compact tissue. The ventricles were filled 
with serous fluid, and the plexus choroides were injected and of a 
violet colour. 
Turn sick in the Human Being .—I have heard of affections of 
the brain in the human being, in which there has been a peculiar 
uncertainty of gait and tendency to this circular motion, and in 
which, when the patient sat up, he described with his head, yet 
very imperfectly, these rotatory movements, and always the same 
way, and with the head inclined, and sometimes permanently, to 
one side. I have understood that this has been attributed to 
partial local pressure on the brain, but I have read of only one 
case in which the hydatid w 7 as the apparent cause of these sin¬ 
gular phenomena. I am, however, far too ignorant on this 
subject, as it regards my own patients, to be warranted in ha¬ 
zarding a conjecture respecting any similar malady in the biped. 
