52 
ON POUCHED HEART. 
These changes in breed are the results of the quality and 
quantity of the blood; but it by no means follows that healthy 
development of the muscular system is the result of such 
changes. 
When there is a greater quantity of venous blood in the 
right ventricle than what is natural, it remains there a longer 
time than is consistent with the healthy contraction of the 
heart, and interferes with the fitting capacity of the lungs. 
That which in a proper quantity and quality is a healthy 
stimulus, otherwise becomes a source of morbid irritation. 
When, too, it is known that so minute a quantity as one ten- 
thousandth part of some bodies completely changes the cha¬ 
racter of the compound with which they may be combined, 
there is no need of surprise as to the morbific effects of un¬ 
healthy blood, because of the minute deviation scarcely ap¬ 
preciable from its healthy condition. 
In the words of a celebrated physiologist, “ To preserve 
health, the natural quantity and quality of the blood must be 
in strict relation with the power of the heart and the capacity 
of the lungs. There is no doubt that a certain composition of 
the blood is one of the most important conditions to a due 
exercise of the different functions” (Majendie). 
Here, then, the composition of the blood is all-important to 
the exercise of the different functions. When the venous 
blood is in excess, the ventricle does not act simultaneously; 
so that, after it has overcome its difficulty, the part so unusually 
irritated becomes dilated or pouched. This effect is augmented 
by the increase of density and of the specific gravity of the 
blood, in which there is an excess of carbon. 
The disease of “ pouched heart” once established, the animal 
is removed from a healthy state. The proportion of venous 
blood increases through the carcass: the fluid is not only 
altered in healthy quantity, but its healthy qualities also. It 
is deprived of a great part of its natural proportion of fluid, its 
electrical state is altered, its chemical properties are changed. 
The disease in question is observed to commence in that 
part of the ventricle which would be most influenced by the 
extra weight of the contained blood; that is, opposite to the 
origin of the pulmonary artery. Here the ventricle first be¬ 
comes thin. As the disease advances, the dilatation of the 
cavity goes on, from before backwards, to the entire enlarge¬ 
ment of the ventricle, down to the apex, where the septum 
divides the right from the left side of the heart. The dilated 
ventricle becomes thinner and is puckered. The corresponding 
auricle, too, is dilated, and is thrust quite to the back part of 
the organ. The valvular apparatus, between the auricle and 
the ventricle, is altered in its connexions, and fails to close. 
In this extreme case the jugular veins pulsate like arteries, 
