526 MR. youatt’s veterinary lectures. 
a second incision should be made with the knife through the 
pericranium and the membranes of the brain. It will be a 
matter of some importance, and more interest, to extract the 
hydatid whole; but that will not often be practicable. Every 
portion of it, however, must be carefully removed: the head of 
the sheep must be so held that all the fluid may escape; and 
then the membranes and the integument must be restored to 
their situation, and a soft pledget, or, what is better, an adhesive 
plaster, must be put over the whole. 
The Appearance of the Cranial Cavity .—Mr. Stephens, at 
one of the meetings of the London Medical Society in 1831, gave 
the following account of an operation on a sturdied sheep. He 
took out a portion of bone with the trephine; and, on cutting 
through the dura mater, a very large hydatid partially protruded. 
This he attempted to extract, but the cyst broke. He after¬ 
wards extracted the cyst; and, on looking through the opening 
made with the trephine, he found the interior to present a large 
empty cavity, and the brain appeared completely gone. He 
then let down a light into the opening—into the very cavity of 
the skull—by which it appeared that nearly the whole of the 
cerebrum was wanting. The opening being afterwards closed, 
the sheep got up and fed, and seemed better for the three fol¬ 
lowing days; but on the morning of the fourth day he found it 
convulsed, and in that state it soon died. 
External Puncture, —Some, afraid of the large opening into 
the cranium caused by the trephine, have contented themselves 
with puncturing the cyst at the spot at which the skull is 
softened. A common awl is used for this purpose. The fluid 
usually spirts out violently at first; but there is no certainty of 
its being all discharged, or of the hydatid being destroyed by 
this simple puncture. I do not see that anything is gained by 
this mode of going to work, for there is no danger in the mere 
operation with the trephine; the danger arises from causes 
common to both—the new cavity formed, and the admission of 
atmospheric air; while there is the advantage attending the tre¬ 
phine of destroying the cyst, and perhaps detecting others in 
contact with it. 
Cautery .—Some have recommended a heated iron as the in¬ 
strument for effecting the perforation ; but this is a relic of far¬ 
riers’ barbarity, and is objectionable from its tendency to produce 
or to increase that inflammation which is too apt to arise however 
we operate. 
Injections .—When the hydatid has not been completely re¬ 
moved, it has been proposed to inject certain fluids into the 
cavitv to ensure the destruction of the animalcule. Tincture of 
