PROGRESS OF VETERINARY SCIENCE AND ART. 155 
are pithed, the walls and contents of the thorax are paralysed* 
the heart becomes an inert bag filled with fluid* the jerk of 
which* as the animal falls* causes rupture of the containing 
vessel at its weakest part ; and this is, in truth, the vena 
azygos, whose walls are thin* and only protected by the 
pleura. At my suggestion, Professor Maffei instituted a 
series of observations to determine the frequency of the lesion 
under consideration ; and, with his customary courtesy and 
exactness* thus communicated the result: “From the 1st of 
June, 1854* to this date (28th May* 1855), 3095 oxen and 
cows were killed in the public slaughter-houses. 1 have met 
with the rupture of the azygos in fifty-seven of these animals ; 
these ruptures occur in various parts of the said vein ; at 
times, where the intercostals join it* and at others* where the 
vein curves round, empties itself into the anterior vena cava 
Such lacerations seem to occur about the same number of 
times in either of these situations ; they bear the character 
of regular tears* inducing an effusion of blood between the 
laminae of the mediastinum, or beneath the parietal pleura. 
Sometimes the vital fluid flows into the thorax itself. 
My brother considers the instances of rupture of the 
azygos as bearing on the cases of rupture of the heart by con- 
trecoup* and of wdiich but one is recorded in the horse* and 
that by Mr. Parker, in the Veterinarian for 1855. 
Diseases of the heart in animals* and especially in cattle, 
are very common but rarely diagnosed* and most of them 
completely elude detection. I have many drawings of polypi 
in the heart growing from the auriculo-ventricular valves* of 
deposits beneath the endocardium; of tumours outside the 
heart consisting in masses of cysts* and due to the develop- 
ment of hydatids of the echinococcusveterinorum. The valves 
of the heart are often diseased; and there are two cases, one 
in Alfort* and another in the museum of the London Vete- 
rinary College, of calcification of the walls of the left ven- 
tricle, the degeneration having extended to the complete 
induration of the ventricular septum. It is difficult to 
account for the blood’s circulation through the system in 
these cases. The flow is languid* but enough for the main- 
tenance of nutrition and the support of life. 
The most common cause of diseases of the heart in cattle, 
is the passage of needles from the reticulum through the 
diaphragm. 
21, Dublin Street, Edinburgh. 
{To he continued .) 
