240 Epidemics. 



into fractional parts for given seconds of time ; yet, howsoever 

 it is divided, if the result be the difference of i-5th in one 

 hour, what effect will this have upon a system whose cubic 

 contents is greater than that of either the arteries or the 

 veins, and upon a system which, acting synchronously with 

 its supply of blood from the heart, yet in itself has a certain 

 vis vita of its own of a motor nature ? The lesser force 

 will leave the blood to be more dependent for the due and 

 systematic delivery of each fresh amount, at each impulse of 

 the heart, upon its own vis vita ; and if through cold, 

 excessive heat, or any depressing agency in any part, that 

 vis vita is lowered, then the amount of blood will pass tardily 

 into the veins, and its tardy delivery will be chiefly dependent 

 upon the action of the heart, or the impetus with which it 

 arrives at the capillaries from the heart the natural result of 

 which will be a partial and unequally distributed clearance 

 of the capillaries, and increased dilatation and retardation of 

 blood in them, with much local congestion, but of a passive 

 character, with serous rather than fibrous exudations, and, 

 in many instances, a chronic condition of congestion, from 

 blood in its own vessels remaining fluid for long, and there 

 being every now and then an effort in the capillary vis vita 

 to expel its present contents ; but, being in a chronic state of 

 dilatation, the emptied vessels will be quickly refilled, and 

 kept distended; whilst, if the power of the heart is more 

 complete, and congestion does occur, it is not from want of 

 power in the capillaries to complete the task laid upon them, 

 for the heart itself, more or less, makes sure of this, if the 

 tubing is left uncontracted. But it is quite possible, under 

 greater force from the heart, if anything occurs to upset or 

 lower the integrity of any particular part, that then the 

 capillaries, by over friction, become irritated, and contract 

 too much, or their contraction lasts too long, so that arterial 

 blood flows too freely to the contracted tubes, and a 



