DISEASES OF THE HEART IN DOMESTIC ANIMALS. 
411 
found after endocarditis and carditis. An aneurism, provided 
with ligamentous, cellulo fibrous and callous changes, is an expan¬ 
sion, formed in the wall of the heart, or a round sac which commu¬ 
nicates with the cavity of the heart by means of a separate canal, 
or by means of a space corresponding to its cavity. Aneurism, 
varying in size from a pea bean to a nut, egg and larger, is found 
arising from a broad basis or lying Hat on a pedicle. The form 
and expansion depend mostly upon the metamorphosis in the 
muscle of the heart and its pressure, compactness and relaxation 
in the structure; next upon the original grade and constitution, 
tension and power of resistance of the aneurismatic spot. This 
aneurism is to be regarded as a partial expansion, or as a rupture 
of substance within the altered walls of the heart, whilst the 
opposite surface of the wall still possesses sufficient power of 
resistance to promote the extension of an aneurism. As in arteri- 
eurisma generally, the cavity of the heart aneurisms is tilled with 
compact layers of fibrinous coagulation. The more completely 
broken down the structure of the muscle, the more numerous are 
these layers. Often ragged, wart-like growths are present upon 
the inner surface of the aneurisms of the heart. 
Rupture of the Heart—Rupture Cardis. 
.Rupture of the heart is a severing of the attachment of the 
wall of the heart, causing an effusion of blood in the pericardium. 
The laceration must be complete through the whole thickness of 
the muscular substance. Such a laceration is spontaneous. We 
find lacerations caused by foreign bodies from without; in rumi- 
nents they frequently occur from the reticulum. In older liter¬ 
ature, comparatively few such cases of rupture of the heart are re¬ 
corded, whilst at the present time they are mentioned quite often. 
The condition at a post-mortem examination is not always the 
same. Exteution and direction of the rupture, form and number 
are varied ; sometimes close together, sometimes far apart, it can 
cover one or both chambers. 
After the laceration has taken place the inpouring blood accu¬ 
mulates in the pericardium, which then resembles a dark bluish 
bladder. Partial rupture within the muscular substance and only 
through a few layers also occurs, whereby then the blood extrav- 
