TUBERCULAR ABSCESS IN A STIRK. 
187 
a particle of injesta between its plicae. These were all the 
alterations from a natural state of things that we could detect 
in any of the abdominal viscera, by careful observation. But 
on laying open the chest, we perceived an enormous tumour, 
situated centrally in the thoracic cavity, within the superior 
mediastinum ; inferiorly placed to the posterior aorta ; ex- 
tending as far forward as the curvature of that vessel, and as 
far back as the bodies of the eighth or ninth dorsal vertebra. 
It was elliptical in form, its conjugate diameter longitudinally 
placed with the long axis of the body, situated between the 
duplicatures of pleurae, which form the superior mediastinum, 
to the rough surface of the parietal portions of which it was 
slightly attached ; though more firmly suspended by areolar 
tissue to the origin of the longus colli, and the bodies of the 
vertebral bones, under which it was placed. It had then the 
posterior aorta, &c. on its superior part ; the oesophagus and 
pneumo-gastric nerves on its inferior, upon which it seemed 
to rest ; for there was quite a deflection in their course at this 
part. It was more or less surrounded by loose areolar 
tissue, imbedded in which were several of the bronchial 
lymphatic glands, some of which were morbidly enlarged, 
having slight depositions of tubercular matter within their 
bodies, and some serous fluid in their adjacent tissues. 
The tumour was next removed from its situation. All its 
connecting textures and investing membranes being dissected 
off, it was found to be a closed sac, having no communica- 
tion with any external outlet, and weighing about 14lbs. 
Upon puncturing it, about two quarts of fluid, of a creamy 
yellow colour and consistency flowed out (altogether resem- 
bling pus), from which a most deadly effluvium arose. On 
more freely laying open the sac, it was found that its internal 
surface was covered with small papillae-like protuberances, 
resembling granulations of an unhealthy character; upon and 
around which a large quantity of tubercular matter was 
deposited, and especially on that part which, when the 
tumour was in situ, and the animal in an erect or standing 
position, formed the floor of the sac : although gravity might 
augment the quantity found here, it was, nevertheless,* easily 
detectible on every portion of its internal surface. The walls 
of the sac were of about three eighths of an inch in thickness 
on the average, though as much as half an inch in some parts, 
especially around its conjugate diameter, being thinnest and 
least dense around its transverse. 
Like other abscesses, the walls were quite adventitious in 
character, appearing to be composed of pseudo-organised 
layers of fibrine, in a semi-vascularised condition ; between 
