d with acute rheumatism, the disease is only in rare
instances directly fatal, but in the great majority of cases it leaves
permanent organic changes, which sooner or later develop into valvular
affections, and these may eventually destroy life. When the disease
occurs, however, as the result of pyaemia (blood-poisoning produced by
the absorption of decomposing pus or "matter") or of diphtheria, or when
it is associated with any other septic conditions, it constitutes a very
grave element. Collections of matter formed on the membrane lining the
heart and covering its valves, are liable to be detached and carried by
the circulation to the brain, spleen, or liver, where they plug up some
artery, and thus cause death of the parts which it supplies with blood.

Chronic endocarditis generally occurs in rheumatic subjects,
unassociated with any acute disease, It may exist without any marked
symptoms, except, perhaps, a sense of oppression and uneasiness in the
chest, with palpitation. It produces a thickening and hardening of the
membrane lining the heart, and generally causes a retraction, adhesion,
and degeneration of some of the valves of the heart, thus bringing on
valvular disease.

VALVULAR LESIONS are, as we have seen, very frequently the result of
endocarditis. They are of two kinds. First, those which prevent the
valves from flapping back close to the walls of the ventricles, or
arteries, thus diminishing, to a greater or lesser extent, the size of
the valvular orifices, and offering an obstruction to the free flow of
blood through them; and which consist of a thickening and retraction, or
adhesion of the valves, chalky deposits, morbid growths, etc. Secondly,
those which prevent complete closure of the valves, and thus permit a
return of the blood into the cavity from which it has just been
expelled. These latter consist of retractions, perforations, and partial
detachments of the valves, chalky deposits around the base of the valves
and in them, and rupture of the chordae tendineae.

These two forms of lesions are usually co-existent, one generally being
more extensive than the other. Thus, the regurgitation may be slight,
and the obstruction great, or _vice versa_. The symptoms and disturbance
of the circulation are altogether dependent upon the location and form
of the lesion, or lesions. Each valvular lesion has its characteristic
sound, or murmur, which is heard at a particular period in the cycle of
the hear