236 MR. youatt’s veterinary lectures. 
of suppuration commences, and proceeds until the contents of 
the cyst become again fluid, but of a different character,*'for it 
now consists of pus. The pus increases ; the cyst becomes more 
and more distended; it encroaches on the substance of the lungs 
on every side; it comes into contact with other tubercles, and 
the walls opposed to each other are absorbed by their mutual 
pressure ; they run together, and form one cyst: morbid anato¬ 
mists term this a vomica. It is no process of ulceration, no cor¬ 
roding or eating into the substance of the lungs, but a gradually 
increasing and regular excavation, and this sometimes runs on 
to a very great extent, until a considerable portion of the lung is, 
as it were, hollowed out. By and by, however, the vomica presses 
upon some bronchial passage, and the cyst gives way ; and the 
purulent contents are poured into the bronchise, and got rid of 
by the act of coughing: a great quantity of pus, and often foetid, 
is thrown up ; at other times the quantity is too great to be thus 
got rid of, and the animal is suffocated. Sometimes it will break 
through the pleuritic covering of the lung, and pour its contents 
into the thorax. 
Abscesses may exist in the Liaigs undiscovered. —It is scarcely 
conceivable to what extent these abscesses may exist in animals 
of slow work, without their being discovered by the usual means 
of examination. Mr. Hales tells us that he gave a physic ball 
to a cart-mare with a bad foot, and she soon afterwards died sud¬ 
denly. When inquiring as to the cause of death, he was told, 
and not very good-humouredly, that his physic had killed her. 
He asked, if it had purged her violently ? “ No ! ” it was replied, 
“ it had not operated at all.” She was opened, and the mystery 
was all unravelled. The thorax was deluged with pus, and there 
were then in the lungs several large abscesses, one of which con¬ 
tained at least a quart of pus. The mare had not shewn a 
symptom of chest affection, and the gentleman to whom she be¬ 
longed, declared that he had believed her to be as sound as any 
horse he had in his possession. 
Sometimes, I believe, there is true ulceration of the lungs, 
and seemingly not connected with the presence of tubercles. I 
cannot tell you how you may ascertain this. I am not sufficiently 
master of auscultation to describe the difference in the sound ; or, 
rather, as no sound would be given immediately from the part 
through which no air passed, it would be impossible to distin¬ 
guish the one from the other. One thing however we know, that 
where the progress of ulceration is rapid the horse must die : 
his wind might be impaired, but his life would not always be 
endangered by the existence of tubercles. 
Resolution of Inf animation, —The resolution or gradual abate- 
