ON DISEASES OF THE HEART OF THE HORSE. 197 
the right ventricle takes place ; and a frequent repetition of this 
occurrence may give rise to an increasing dilatation of this 
cavity. 
An obstacle is now offered to the corresponding auricle, and 
dilatation is the result in this cavity; the right auricle now 
ceases to admit all the blood sent to it by the veins; these ves¬ 
sels become surcharged ; the turgescence extends to the venous 
radicles, affording an opposing resistance to the arteries termi¬ 
nating in them ; a corresponding obstacle is offered in the cavse 
to the absorbents: these vessels, like the veins, dilate and be¬ 
come loaded ; their tonicity is lost; infiltration of the cellular 
membrane takes place externally ; oedema developes itself in 
the various organs internally; serous and sanguineous engorge¬ 
ment daily increases ; and, should not the structure of some im¬ 
portant viscus give way and death rapidly follow the lesion (ex¬ 
emplified in the liver of the mare whose case is narrated in the 
February No., page 80), this fatal event speedily arrives from the 
general debility consequent on the loss of absorption: the nu¬ 
trient supplies daily diminishing, together with the impairment 
of function in the several viscera, the animal sinks exhausted. 
Let us see what takes place when the ventricles are hypertro¬ 
phied. The blood is sent with greater force into the arteries. 
Should it be the left ventricle, the coats of the aortic system are 
strong, and capable of considerable resistance, so as to expe¬ 
rience an energetic shock without lesion. By the time the blood 
arrives at the capillary system, it has lost much of its force; 
and, by the vessels dividing and subdividing, the impulse is still 
less felt, so that the capillary circulation continues to possess its 
ordinary character. That serous cachexy, the result of an hy¬ 
pertrophied state of the left ventricle in the human subject, does 
not commonly occur in the horse. I have witnessed many cases 
of its existence to a considerable extent, without any external 
indications of its presence, after death. 
If the right ventricle is hypertrophied, the effect is widely dif¬ 
ferent. Here the blood is pumped with great force into arteries 
with thin coats, and easily extensible. These arteries are short, 
so that the shock has lost nothing of its force by the time it ar¬ 
rives at their termination, and which is a net-work of vessels 
plunging into a delicate vesicular organ. At this point, also, the 
blood passes into another set of vessels, the pulmonary veins, 
in which a corresponding power to carry the blood onward is 
wanting. An obstacle is thus offered to the arterial trunks ; 
and the consequence is, that blood is sent to a part of this capil¬ 
lary system in which, in a healthy state, it did not circulate ; or 
its vessels arc multiplied. The forcible contraction of the ven- 
