268 
THE EDINBURGH VETERINARY COLLEGE. 
The cause of this diminution seems to be the remarkable mildness 
of the weather during the month, or, at least, that is, perhaps, the 
most probable cause that can be suggested. The falling off in 
number is to be found in those diseases of the air-passages more 
especially observed during the prevalence of cold east or north- 
easterly winds, which, during the past month, have not prevailed 
to much extent. This circumstance suggests the advantage to be 
derived from extended statistical reports, a comparison whereof 
tends much to give clear views of some causes of diseases which 
are often involved in apparent mystery ; and hence, to get quit 
of the difficulty of tracing diseases to their real causes, we often 
attempt to explain their prevalence at certain times, by ascribing 
their occurrence to contagion or infection when much obscurity 
exists. 
The case of rupture of the aorta occurred in a horse belonging 
to a carter, that had been under treatment a few days previously 
to the 30th March for quittor of an aggravated kind, and extensive 
sloughing was at that time taking place. The disease in the foot 
had created considerable constitutional disturbance ; and the pain 
and lameness were so great, that, instead of allowing him to be 
brought daily to be dressed, his case was given in charge of some 
of the more advanced students to treat, and report : indeed, as he 
was about a mile distant, and being almost unable to walk, it was 
necessary to attend on him at his own stable. On going for this 
purpose on the 30th March, the horse was found dead, although 
on the previous day he did not appear at all worse than usual. 
The body was immediately examined, as, from the suddenness of 
the death, it was inferred that rupture of some bloodvessel or vas- 
cular organ had taken place. On laying open the abdomen, no 
appearance of this or any other morbid condition was detected ; 
and, on opening the thorax, the lungs with their coverings and 
attachments were entire and healthy, but the pericardium imme- 
diately presented itself as being the seat of mischief. The cavity 
formed by this membrane was filled with arterial blood : it was, 
therefore, together with the heart, removed carefully from the 
thorax, and brought here for more careful examination, and that 
the students might see and have the nature of the case explained 
to them. The incision that had been made to separate the 
pericardium from the sternum, and to evacuate the blood, shewed 
that rupture of the aorta had taken place. On examining the in- 
terior of the heart, the bicuspid and tricuspid valves were found 
much indurated. The semilunar valves, but more especially the 
aortic ones, were also considerably thickened at their free mar- 
gins; and that part of the general cavity of the aorta in which 
sinuses for these valves are formed, which is ordinarily the thin- 
