468 HYDATID, OR TUMOUR OF THE BRAIN. 
At an immature age the animal becomes the subject of hydatid. 
Before the sinuses of the head are properly developed, the intruder 
gains admittance, and takes up its abode, completely encased in a 
dense membrane on the superior part of the head, and becomes a 
complete source of irritation and pain, gradually continuing to 
enlarge. The fluid found within thq tumour appears to be secreted 
by its lining or inner membrane, and its consistency is similar to 
the fluid found within circumscribed cavities. When the tumour 
is opened, and the contents subjected to microscopic inspection, 
numerous young hydatids may be seen. 
The indicative symptoms of the hydatid cannot well be mistaken. 
At the commencement, the animal runs headlong over every thing 
in its way ; but as the disease advances, it becomes more tranquil, 
seldom shifting its situation, but continually moving in a circular 
direction, and appearing quite sturdy and insensible to surround- 
ing objects — the head inclined to the affected side, and the nose 
pointed to the ground. On examining the eye, the pupil appears 
very much dilated on the diseased side ; and when the head is 
raised, the levator occuli acts violently, and turns the globe of the 
eye quite upwards. 
On further examination, the situation of the tumour may easily 
be detected. Use a little pressure, and a soft and yielding portion 
of the cranium may be distinctly felt ; at the same time the animal 
will exhibit great pain. 
You now know the situation of the hydatid. Adopt the fol- 
lowing treatment, and if the operation be scientifically performed, 
and before the animal becomes too much debilitated and oppressed 
from functional derangement, the operation will succeed in two 
cases out of three. In the first place, clip off the wool, make an 
incision through the skin, lay it aside, and retain it there with a 
stitch. Then take a circular tube of iron that will remove at 
least a portion of the bone the size of a shilling. Lay a piece of 
wet cloth on each side of the wound to defend it from the fire; 
bring your tube to a dull red heat, and apply it with a light hand. 
You will soon penetrate to the substance of the brain, for the 
bone is very thin, and apparently absorbed, in order to adapt itself 
to the tumour. Raise up the bone with a scalpel, and the tumour 
will come through the opening — detach it from its situation care- 
fully, without bursting, if possible ; for if it burst, some of the }’oung 
hydatids may remain. 
As soon as the tumour is removed, close the opening with the 
circular piece of bone, for the external air is detrimental. Lay 
the integuments together, stitch them close, and apply a pitch 
plaister. Then take some wool, dip it in warm pitch, place it 
