AND ANIMAL LIFE. 289 



tutes one form of hypertrophy. If one cavity 

 be less, from disease, than it ought to be, it is 

 clear that its diminished capacity cannot receive 

 the same quantity of blood. If the seat of this mal- 

 conformation be the right auricle, every motion of 

 the bddy that facilitates circulation will be apt to 

 derange or destroy the function of the heart ; or 

 suppose the right ventricle to be dilated) the con- 

 traction of the auricle will send its usual quanti- 

 ty of blood, but a portion of this will, of necessi- 

 ty, regurgitate ; and, if the latter cavity be much 

 excited, it will send more than it is accustomed 

 to transmit, and, in this way, it will hasten the 

 effects called palpitation, or irregular action of 

 the heart. This phenomenon occurs because the 

 augmented cavity is frequently accompanied by 

 debility. The thin parietes in passive aneurism 

 do not present the same quick sound to the ear, 

 the same strong impulse to the hand, nor the same 

 frequent and bounding pulse that are observed in 

 active aneurism. Palpitation in both conditions is 

 produced by the same exciting causes. Whenever 

 a quantity of blood, greater than what is natural, is 

 transmitted to the dilated ventricle or auricle, its 

 attenuated parietes are inadequate to the task of 

 propelling it, the consequence of which is, that 

 the fluid accumulates, and excites the heart to 

 convulsive or irregular action. SEXAC and others 

 have imagined, that the cavity being larger, it 

 must necessarily be more stimulated, as it possess- 



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