3© Dr. Young’s Lecture on the Functions 
Besides these general illustrations of the nature of fevers 
and inflammations, the theory which has been explained may 
sometimes be of use, in enabling us to understand the operation 
of the remedies employed for relieving them. Thus it may be 
shown, that any diminution of the tension of the arterial system 
must be propagated from the point at which it begins, as from 
a centre, nearly in the same manner, and with the same velo- 
city, as an increase of tension, or a pulsation of any kind would 
be propagated. Hence the effect of venesection must be not 
only more rapidly, but also more powerfully felt in a neigh- 
bouring than in a distant part : and although the mean or per- 
manent tension of the vessels of any part must be the same, 
from whatever vein the blood may have been drawn, pro- 
vided that they undergo no local alteration, yet the temporary 
change, produced by opening a vein in their neighbouhood, 
may have relieved them so effectually from an excess of pres- 
sure, as to allow them to recover their natural tone, which 
they could not have done without such a partial exhaustion of 
the neighbouring vessels. But since it seems probable, that 
the minute arteries are more affected by distension than the 
veins, there is reason in general to expect a more speedy and 
efficacious relief in inflammations, from opening an artery 
than a vein: this operation, however, can seldom be performed 
without material inconvenience ; but it is probably for a simi- 
lar reason, that greater benefit is often experienced from 
withdrawing a small portion of blood by means of cupping or 
of leeches, than a much larger quantity by venesection, since 
both the former modes of bleeding tend to relieve the arte- 
ries, as immediately as the veins, from that distension, which 
appears to constitute the most essential characteristic of 
